@phdthesis{Fitzner2024, author = {Fitzner, Maria}, title = {Cultivation of selected halophytes in saline indoor farming and modulation of cultivation conditions to optimize metabolite profiles for human nutrition}, doi = {10.25932/publishup-62697}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-626974}, school = {Universit{\"a}t Potsdam}, pages = {178}, year = {2024}, abstract = {With the many challenges facing the agricultural system, such as water scarcity, loss of arable land due to climate change, population growth, urbanization or trade disruptions, new agri-food systems are needed to ensure food security in the future. In addition, healthy diets are needed to combat non-communicable diseases. Therefore, plant-based diets rich in health-promoting plant secondary metabolites are desirable. A saline indoor farming system is representing a sustainable and resilient new agrifood system and can preserve valuable fresh water. Since indoor farming relies on artificial lighting, assessment of lighting conditions is essential. In this thesis, the cultivation of halophytes in a saline indoor farming system was evaluated and the influence of cultivation conditions were assessed in favor of improving the nutritional quality of halophytes for human consumption. Therefore, five selected edible halophyte species (Brassica oleracea var. palmifolia, Cochlearia officinalis, Atriplex hortensis, Chenopodium quinoa, and Salicornia europaea) were cultivated in saline indoor farming. The halophyte species were selected for to their salt tolerance levels and mechanisms. First, the suitability of halophytes for saline indoor farming and the influence of salinity on their nutritional properties, e.g. plant secondary metabolites and minerals, were investigated. Changes in plant performance and nutritional properties were observed as a function of salinity. The response to salinity was found to be species-specific and related to the salt tolerance mechanism of the halophytes. At their optimal salinity levels, the halophytes showed improved carotenoid content. In addition, a negative correlation was found between the nitrate and chloride content of halophytes as a function of salinity. Since chloride and nitrate can be antinutrient compounds, depending on their content, monitoring is essential, especially in halophytes. Second, regional brine water was introduced as an alternative saline water resource in the saline indoor farming system. Brine water was shown to be feasible for saline indoor farming of halophytes, as there was no adverse effect on growth or nutritional properties, e.g. carotenoids. Carotenoids were shown to be less affected by salt composition than by salt concentration. In addition, the interaction between the salinity and the light regime in indoor farming and greenhouse cultivation has been studied. There it was shown that interacting light regime and salinity alters the content of carotenoids and chlorophylls. Further, glucosinolate and nitrate content were also shown to be influenced by light regime. Finally, the influence of UVB light on halophytes was investigated using supplemental narrow-band UVB LEDs. It was shown that UVB light affects the growth, phenotype and metabolite profile of halophytes and that the UVB response is species specific. Furthermore, a modulation of carotenoid content in S. europaea could be achieved to enhance health-promoting properties and thus improve nutritional quality. This was shown to be dose-dependent and the underlying mechanisms of carotenoid accumulation were also investigated. Here it was revealed that carotenoid accumulation is related to oxidative stress. In conclusion, this work demonstrated the potential of halophytes as alternative vegetables produced in a saline indoor farming system for future diets that could contribute to ensuring food security in the future. To improve the sustainability of the saline indoor farming system, LED lamps and regional brine water could be integrated into the system. Since the nutritional properties have been shown to be influenced by salt, light regime and UVB light, these abiotic stressors must be taken into account when considering halophytes as alternative vegetables for human nutrition.}, language = {en} } @phdthesis{Henning2024, author = {Henning, Thorsten}, title = {Cross-sectional associations of dietary biomarker patterns with health and nutritional status}, school = {Universit{\"a}t Potsdam}, pages = {111}, year = {2024}, language = {en} } @phdthesis{Harbart2024, author = {Harbart, Vanessa}, title = {The effect of protected cultivation on the nutritional quality of lettuce (Lactuca sativa var capitata L.) with a focus on antifogging additives in polyolefin covers}, doi = {10.25932/publishup-62937}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-629375}, school = {Universit{\"a}t Potsdam}, pages = {IV, 115}, year = {2024}, abstract = {Protected cultivation in greenhouses or polytunnels offers the potential for sustainable production of high-yield, high-quality vegetables. This is related to the ability to produce more on less land and to use resources responsibly and efficiently. Crop yield has long been considered the most important factor. However, as plant-based diets have been proposed for a sustainable food system, the targeted enrichment of health-promoting plant secondary metabolites should be addressed. These metabolites include carotenoids and flavonoids, which are associated with several health benefits, such as cardiovascular health and cancer protection. Cover materials generally have an influence on the climatic conditions, which in turn can affect the levels of secondary metabolites in vegetables grown underneath. Plastic materials are cost-effective and their properties can be modified by incorporating additives, making them the first choice. However, these additives can migrate and leach from the material, resulting in reduced service life, increased waste and possible environmental release. Antifogging additives are used in agricultural films to prevent the formation of droplets on the film surface, thereby increasing light transmission and preventing microbiological contamination. This thesis focuses on LDPE/EVA covers and incorporated antifogging additives for sustainable protected cultivation, following two different approaches. The first addressed the direct effects of leached antifogging additives using simulation studies on lettuce leaves (Lactuca sativa var capitata L). The second determined the effect of antifog polytunnel covers on lettuce quality. Lettuce is usually grown under protective cover and can provide high nutritional value due to its carotenoid and flavonoid content, depending on the cultivar. To study the influence of simulated leached antifogging additives on lettuce leaves, a GC-MS method was first developed to analyze these additives based on their fatty acid moieties. Three structurally different antifogging additives (reference material) were characterized outside of a polymer matrix for the first time. All of them contained more than the main fatty acid specified by the manufacturer. Furthermore, they were found to adhere to the leaf surface and could not be removed by water or partially by hexane. The incorporation of these additives into polytunnel covers affects carotenoid levels in lettuce, but not flavonoids, caffeic acid derivatives and chlorophylls. Specifically, carotenoids were higher in lettuce grown under polytunnels without antifog than with antifog. This has been linked to their effect on the light regime and was suggested to be related to carotenoid function in photosynthesis. In terms of protected cultivation, the use of LDPE/EVA polytunnels affected light and temperature, and both are closely related. The carotenoid and flavonoid contents of lettuce grown under polytunnels was reversed, with higher carotenoid and lower flavonoid levels. At the individual level, the flavonoids detected in lettuce did not differ however, lettuce carotenoids adapted specifically depending on the time of cultivation. Flavonoid reduction was shown to be transcriptionally regulated (CHS) in response to UV light (UVR8). In contrast, carotenoids are thought to be regulated post-transcriptionally, as indicated by the lack of correlation between carotenoid levels and transcripts of the first enzyme in carotenoid biosynthesis (PSY) and a carotenoid degrading enzyme (CCD4), as well as the increased carotenoid metabolic flux. Understanding the regulatory mechanisms and metabolite adaptation strategies could further advance the strategic development and selection of cover materials.}, language = {en} } @phdthesis{Prada2023, author = {Prada, Marcela}, title = {Fatty acid biomarkers of intake and metabolism and their association with type 2 diabetes}, doi = {10.25932/publishup-58159}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-581598}, school = {Universit{\"a}t Potsdam}, pages = {142}, year = {2023}, abstract = {Background: The role of fatty acid (FA) intake and metabolism in type 2 diabetes (T2D) incidence is controversial. Some FAs are not synthesised endogenously and, therefore, these circulating FAs reflect dietary intake, for example, the trans fatty acids (TFAs), saturated odd chain fatty acids (OCFAs), and linoleic acid, an n-6 polyunsaturated fatty acids (PUFA). It remains unclear if intake of TFA influence T2D risk and whether industrial TFAs (iTFAs) and ruminant TFAs (rTFAs) exert the same effect. Unlike even chain saturated FAs, the OCFAs have been inversely associated with T2D risk, but this association is poorly understood. Furthermore, the associations of n-6 PUFAs intake with T2D risk are still debated, while delta-5 desaturase (D5D), a key enzyme in the metabolism of PUFAs, has been consistently related to T2D risk. To better understand these relationships, the FA composition in circulating lipid fractions can be used as biomarkers of dietary intake and metabolism. The exploration of TFAs subtypes in plasma phospholipids and OCFAs and n-6 PUFAs within a wide range of lipid classes may give insights into the pathophysiology of T2D. Aim: This thesis aimed mainly to analyse the association of TFAs, OCFAs and n-6 PUFAs with self-reported dietary intake and prospective T2D risk, using seven types of TFAs in plasma phospholipids and deep lipidomics profiling data from fifteen lipid classes. Methods: A prospective case-cohort study was designed within the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam study, including all the participants who developed T2D (median follow-up 6.5 years) and a random subsample of the full cohort (subcohort: n=1248; T2D cases: n=820). The main analyses included two lipid profiles. The first was an assessment of seven TFA in plasma phospholipids, with a modified method for analysis of FA with very low abundances. The second lipid profile was derived from a high-throughout lipid profiling technology, which identified 940 distinct molecular species and allowed to quantify OCFAs and PUFAs composition across 15 lipid classes. Delta-5 desaturase (D5D) activity was estimated as 20:4/20:3-ratio. Using multivariable Cox regression models, we examined the associations of TFA subtypes with incident T2D and class-specific associations of OCFA and n-6 PUFAs with T2D risk. Results: 16:1n-7t, 18:1n-7t, and c9t11-CLA were positively correlated with the intake of fat-rich dairy foods. iTFA 18:1 isomers were positively correlated with margarine. After adjustment for confounders and other TFAs, higher plasma phospholipid concentrations of two rTFAs were associated with a lower incidence of T2D: 18:1n-7t and t10c12-CLA. In contrast, the rTFA c9t11-CLA was associated with a higher incidence of T2D. rTFA 16:1n-7t and iTFAs (18:1n-6t, 18:1n-9t, 18:2n-6,9t) were not statistically significantly associated with T2D risk. We observed heterogeneous integration of OCFA in different lipid classes, and the contribution of 15:0 versus 17:0 to the total OCFA abundance differed across lipid classes. Consumption of fat-rich dairy and fiber-rich foods were positively and red meat inversely correlated to OCFA abundance in plasma phospholipid classes. In women only, higher abundances of 15:0 in phosphatidylcholines (PC) and diacylglycerols (DG), and 17:0 in PC, lysophosphatidylcholines (LPC), and cholesterol esters (CE) were inversely associated with T2D risk. In men and women, a higher abundance of 15:0 in monoacylglycerols (MG) was also inversely associated with T2D. Conversely, a higher 15:0 concentration in LPC and triacylglycerols (TG) was associated with higher T2D risk in men. Women with a higher concentration of 17:0 as free fatty acids (FFA) also had higher T2D incidence. The integration of n-6 PUFAs in lipid classes was also heterogeneous. 18:2 was highly abundant in phospholipids (particularly PC), CE, and TG; 20:3 represented a small fraction of FA in most lipid classes, and 20:4 accounted for a large proportion of circulating phosphatidylinositol (PI) and phosphatidylethanolamines (PE). Higher concentrations of 18:2 were inversely associated with T2D risk, especially within DG, TG, and LPC. However, 18:2 as part of MG was positively associated with T2D risk. Higher concentrations of 20:3 in phospholipids (PC, PE, PI), FFA, CE, and MG were linked to higher T2D incidence. 20:4 was unrelated to risk in most lipid classes, except positive associations were observed for 20:4 enriched in FFA and PE. The estimated D5D activities in PC, PE, PI, LPC, and CE were inversely associated with T2D and explained variance of estimated D5D activity by genomic variation in the FADS locus was only substantial in those lipid classes. Conclusion: The TFAs' conformation is essential in their relationship to diabetes risk, as indicated by plasma rTFA subtypes concentrations having opposite directions of associations with diabetes risk. Plasma OCFA concentration is linked to T2D risk in a lipid class and sex-specific manner. Plasma n-6 PUFA concentrations are associated differently with T2D incidence depending on the specific FA and the lipid class. Overall, these results highlight the complexity of circulating FAs and their heterogeneous association with T2D risk depending on the specific FA structure, lipid class, and sex. My results extend the evidence of the relationship between diet, lipid metabolism, and subsequent T2D risk. In addition, my work generated several potential new biomarkers of dietary intake and prospective T2D risk.}, language = {en} } @phdthesis{Drobyshev2023, author = {Drobyshev, Evgenii}, title = {Toxic or beneficial? What is the role of food-relevant selenium species selenoneine?}, doi = {10.25932/publishup-57379}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-573794}, school = {Universit{\"a}t Potsdam}, pages = {xiv, 100}, year = {2023}, abstract = {Selenium (Se) is an essential trace element that is ubiquitously present in the environment in small concentrations. Essential functions of Se in the human body are manifested through the wide range of proteins, containing selenocysteine as their active center. Such proteins are called selenoproteins which are found in multiple physiological processes like antioxidative defense and the regulation of thyroid hormone functions. Therefore, Se deficiency is known to cause a broad spectrum of physiological impairments, especially in endemic regions with low Se content. Nevertheless, being an essential trace element, Se could exhibit toxic effects, if its intake exceeds tolerable levels. Accordingly, this range between deficiency and overexposure represents optimal Se supply. However, this range was found to be narrower than for any other essential trace element. Together with significantly varying Se concentrations in soil and the presence of specific bioaccumulation factors, this represents a noticeable difficulty in the assessment of Se epidemiological status. While Se is acting in the body through multiple selenoproteins, its intake occurs mainly in form of small organic or inorganic molecular mass species. Thus, Se exposure not only depends on daily intake but also on the respective chemical form, in which it is present. The essential functions of selenium have been known for a long time and its primary forms in different food sources have been described. Nevertheless, analytical capabilities for a comprehensive investigation of Se species and their derivatives have been introduced only in the last decades. A new Se compound was identified in 2010 in the blood and tissues of bluefin tuna. It was called selenoneine (SeN) since it is an isologue of naturally occurring antioxidant ergothioneine (ET), where Se replaces sulfur. In the following years, SeN was identified in a number of edible fish species and attracted attention as a new dietary Se source and potentially strong antioxidant. Studies in populations whose diet largely relies on fish revealed that SeN represents the main non-protein bound Se pool in their blood. First studies, conducted with enriched fish extracts, already demonstrated the high antioxidative potential of SeN and its possible function in the detoxification of methylmercury in fish. Cell culture studies demonstrated, that SeN can utilize the same transporter as ergothioneine, and SeN metabolite was found in human urine. Until recently, studies on SeN properties were severely limited due to the lack of ways to obtain the pure compound. As a predisposition to this work was firstly a successful approach to SeN synthesis in the University of Graz, utilizing genetically modified yeasts. In the current study, by use of HepG2 liver carcinoma cells, it was demonstrated, that SeN does not cause toxic effectsup to 100 μM concentration in hepatocytes. Uptake experiments showed that SeN is not bioavailable to the used liver cells. In the next part a blood-brain barrier (BBB) model, based on capillary endothelial cells from the porcine brain, was used to describe the possible transfer of SeN into the central nervous system (CNS). The assessment of toxicity markers in these endothelial cells and monitoring of barrier conditions during transfer experiments demonstrated the absence of toxic effects from SeN on the BBB endothelium up to 100 μM concentration. Transfer data for SeN showed slow but substantial transfer. A statistically significant increase was observed after 48 hours following SeN incubation from the blood-facing side of the barrier. However, an increase in Se content was clearly visible already after 6 hours of incubation with 1 μM of SeN. While the transfer rate of SeN after application of 0.1 μM dose was very close to that for 1 μM, incubation with 10 μM of SeN resulted in a significantly decreased transfer rate. Double-sided application of SeN caused no side-specific transfer of SeN, thus suggesting a passive diffusion mechanism of SeN across the BBB. This data is in accordance with animal studies, where ET accumulation was observed in the rat brain, even though rat BBB does not have the primary ET transporter - OCTN1. Investigation of capillary endothelial cell monolayers after incubation with SeN and reference selenium compounds showed no significant increase of intracellular selenium concentration. Speciesspecific Se measurements in medium samples from apical and basolateral compartments, as good as in cell lysates, showed no SeN metabolization. Therefore, it can be concluded that SeN may reach the brain without significant transformation. As the third part of this work, the assessment of SeN antioxidant properties was performed in Caco-2 human colorectal adenocarcinoma cells. Previous studies demonstrated that the intestinal epithelium is able to actively transport SeN from the intestinal lumen to the blood side and accumulate SeN. Further investigation within current work showed a much higher antioxidant potential of SeN compared to ET. The radical scavenging activity after incubation with SeN was close to the one observed for selenite and selenomethionine. However, the SeN effect on the viability of intestinal cells under oxidative conditions was close to the one caused by ET. To answer the question if SeN is able to be used as a dietary Se source and induce the activity of selenoproteins, the activity of glutathione peroxidase (GPx) and the secretion of selenoprotein P (SelenoP) were measured in Caco-2 cells, additionally. As expected, reference selenium compounds selenite and selenomethionine caused efficient induction of GPx activity. In contrast to those SeN had no effect on GPx activity. To examine the possibility of SeN being embedded into the selenoproteome, SelenoP was measured in a culture medium. Even though Caco-2 cells effectively take up SeN in quantities much higher than selenite or selenomethionine, no secretion of SelenoP was observed after SeN incubation. Summarizing, we can conclude that SeN can hardly serve as a Se source for selenoprotein synthesis. However, SeN exhibit strong antioxidative properties, which appear when sulfur in ET is exchanged by Se. Therefore, SeN is of particular interest for research not as part of Se metabolism, but important endemic dietary antioxidant.}, language = {en} } @phdthesis{LopesFernando2023, author = {Lopes Fernando, Raquel Sofia}, title = {The impact of aging on proteolytic systems, transcriptome and metabolome of slow and fast muscle fiber types}, doi = {10.25932/publishup-60579}, school = {Universit{\"a}t Potsdam}, pages = {XI, 125}, year = {2023}, abstract = {Aging is a complex process characterized by several factors, including loss of genetic and epigenetic information, accumulation of chronic oxidative stress, protein damage and aggregates and it is becoming an emergent drug target. Therefore, it is the utmost importance to study aging and agerelated diseases, to provide treatments to develop a healthy aging process. Skeletal muscle is one of the earliest tissues affected by age-related changes with progressive loss of muscle mass and function from 30 years old, effect known as sarcopenia. Several studies have shown the accumulation of protein aggregates in different animal models, as well as in humans, suggesting impaired proteostasis, a hallmark of aging, especially regarding degradation systems. Thus, different publications have explored the role of the main proteolytic systems in skeletal muscle from rodents and humans, like ubiquitin proteasomal system (UPS) and autophagy lysosomal system (ALS), however with contradictory results. Yet, most of the published studies are performed in muscles that comprise more than one fiber type, that means, muscles composed by slow and fast fibers. These fiber types, exhibit different metabolism and contraction speed; the slow fibers or type I display an oxidative metabolism, while fast fibers function towards a glycolytic metabolism ranging from fast oxidative to fast glycolytic fibers. To this extent, the aim of this thesis sought to understand on how aging impacts both fiber types not only regarding proteostasis but also at a metabolome and transcriptome network levels. Therefore, the first part of this thesis, presents the differences between slow oxidative (from Soleus muscle) and fast glycolytic fibers (Extensor digitorum longus, EDL) in terms of degradation systems and how they cope with oxidative stress during aging, while the second part explores the differences between young and old EDL muscle transcriptome and metabolome, unraveling molecular features. More specifically, the results from the present work show that slow oxidative muscle performs better at maintaining the function of UPS and ALS during aging than EDL muscle, which is clearly affected, accounting for the decline in the catalytic activity rates and accumulation of autophagy-related proteins. Strinkingly, transcriptome and metabolome analyses reveal that fast glycolytic muscle evidences significant downregulation of mitochondrial related processes and damaged mitochondria morphology during aging, despite of having a lower oxidative metabolism compared to oxidative fibers. Moreover, predictive analyses reveal a negative association between aged EDL gene signature and lifespan extending interventions such as caloric restriction (CR). Although, CR intervention does not alter the levels of mitochondrial markers in aged EDL muscle, it can reverse the higher mRNA levels of muscle damage markers. Together, the results from this thesis give new insights about how different metabolic muscle fibers cope with age-related changes and why fast glycolytic fibers are more susceptible to aging than slow oxidative fibers.}, language = {en} } @phdthesis{Raschke2023, author = {Raschke, Stefanie}, title = {Characterization of selenium and copper in cell systems of the neurovascular unit}, doi = {10.25932/publishup-60366}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-603666}, school = {Universit{\"a}t Potsdam}, pages = {XIV, 184, v}, year = {2023}, abstract = {The trace elements, selenium (Se) and copper (Cu) play an important role in maintaining normal brain function. Since they have essential functions as cofactors of enzymes or structural components of proteins, an optimal supply as well as a well-defined homeostatic regulation are crucial. Disturbances in trace element homeostasis affect the health status and contribute to the incidence and severity of various diseases. The brain in particular is vulnerable to oxidative stress due to its extensive oxygen consumption and high energy turnover, among other factors. As components of a number of antioxidant enzymes, both elements are involved in redox homeostasis. However, high concentrations are also associated with the occurrence of oxidative stress, which can induce cellular damage. Especially high Cu concentrations in some brain areas are associated with the development and progression of neurodegenerative diseases such as Alzheimer's disease (AD). In contrast, reduced Se levels were measured in brains of AD patients. The opposing behavior of Cu and Se renders the study of these two trace elements as well as the interactions between them being particularly relevant and addressed in this work.}, language = {en} } @phdthesis{Koelman2023, author = {Koelman, Liselot A.}, title = {The role of diet in immune health and ageing}, school = {Universit{\"a}t Potsdam}, year = {2023}, language = {en} } @phdthesis{Wittek2023, author = {Wittek, Laura}, title = {Comparison of metabolic cages - analysis of refinement measures on the welfare and metabolic parameters of laboratory mice}, doi = {10.25932/publishup-61120}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-611208}, school = {Universit{\"a}t Potsdam}, pages = {IV, 160}, year = {2023}, abstract = {Housing in metabolic cages can induce a pronounced stress response. Metabolic cage systems imply housing mice on metal wire mesh for the collection of urine and feces in addition to monitoring food and water intake. Moreover, mice are single-housed, and no nesting, bedding, or enrichment material is provided, which is often argued to have a not negligible impact on animal welfare due to cold stress. We therefore attempted to reduce stress during metabolic cage housing for mice by comparing an innovative metabolic cage (IMC) with a commercially available metabolic cage from Tecniplast GmbH (TMC) and a control cage. Substantial refinement measures were incorporated into the IMC cage design. In the frame of a multifactorial approach for severity assessment, parameters such as body weight, body composition, food intake, cage and body surface temperature (thermal imaging), mRNA expression of uncoupling protein 1 (Ucp1) in brown adipose tissue (BAT), fur score, and fecal corticosterone metabolites (CMs) were included. Female and male C57BL/6J mice were single-housed for 24 h in either conventional Macrolon cages (control), IMC, or TMC for two sessions. Body weight decreased less in the IMC (females—1st restraint: 6.94\%; 2nd restraint: 6.89\%; males—1st restraint: 8.08\%; 2nd restraint: 5.82\%) compared to the TMC (females—1st restraint: 13.2\%; 2nd restraint: 15.0\%; males—1st restraint: 13.1\%; 2nd restraint: 14.9\%) and the IMC possessed a higher cage temperature (females—1st restraint: 23.7°C; 2nd restraint: 23.5 °C; males—1st restraint: 23.3 °C; 2nd restraint: 23.5 °C) compared with the TMC (females—1st restraint: 22.4 °C; 2nd restraint: 22.5 °C; males—1st restraint: 22.6 °C; 2nd restraint: 22.4 °C). The concentration of fecal corticosterone metabolites in the TMC (females—1st restraint: 1376 ng/g dry weight (DW); 2nd restraint: 2098 ng/g DW; males—1st restraint: 1030 ng/g DW; 2nd restraint: 1163 ng/g DW) was higher compared to control cage housing (females—1st restraint: 640 ng/g DW; 2nd restraint: 941 ng/g DW; males—1st restraint: 504 ng/g DW; 2nd restraint: 537 ng/g DW). Our results show the stress potential induced by metabolic cage restraint that is markedly influenced by the lower housing temperature. The IMC represents a first attempt to target cold stress reduction during metabolic cage application thereby producing more animal welfare friendly data.}, language = {en} } @phdthesis{Rausch2023, author = {Rausch, Theresa}, title = {Role of intestinal bacteria in the conversion of dietary sulfonates}, doi = {10.25932/publishup-57403}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-574036}, school = {Universit{\"a}t Potsdam}, pages = {XXI, 98, LXIV}, year = {2023}, abstract = {Over the last decades, interest in the impact of the intestinal microbiota on host health has steadily increased. Diet is a major factor that influences the gut microbiota and thereby indirectly affects human health. For example, a high fat diet rich in saturated fatty acids led to an intestinal proliferation of the colitogenic bacterium Bilophila (B.) wadsworthia by stimulating the release of the bile acid taurocholate (TC). TC contains the sulfonated head group taurine, which undergoes conversion to sulfide (H2S) by B. wadsworthia. In a colitis prone murine animal model (IL10 / mice), the bloom of B. wadsworthia was accompanied by an exacerbation of intestinal inflammation. B. wadsworthia is able to convert taurine and also other sulfonates to H2S, indicating the potential association of sulfonate utilization and the stimulation of colitogenic bacteria. This potential link raised the question, whether dietary sulfonates or their sulfonated metabolites stimulate the growth of colitogenic bacteria such as B. wadsworthia and whether these bacteria convert sulfonates to H2S. Besides taurine, which is present in meat, fish and life-style beverages, other dietary sulfonates are part of daily human nutrition. Sulfolipids such as sulfoquinovosyldiacylglycerols (SQDG) are highly abundant in salad, parsley and the cyanobacterium Arthrospira platensis (Spirulina). Based on previous findings, Escherichia (E.) coli releases the polar headgroup sulfoquinovose (SQ) from SQDG. Moreover, E. coli is able to convert SQ to 2,3 dihydroxypropane 1 sulfonate (DHPS) under anoxic conditions. DHPS is also converted to H2S by B. wadsworthia or by other potentially harmful gut bacteria such as members of the genus Desulfovibrio. However, only few studies report the conversion of sulfonates to H2S by bacteria directly isolated from the human intestinal tract. Most sulfonate utilizing bacteria were obtained from environmental sources such as soil or lake sediment or from potentially intestinal sources such as sewage. In the present study, fecal slurries from healthy human subjects were incubated with sulfonates under strictly anoxic conditions, using formate and lactate as electron donors. Fecal slurries that converted sulfonates to H2S, were used as a source for the isolation of H2S forming bacteria. Isolates were identified based on their 16S ribosomal RNA (16S rRNA) gene sequence. In addition, conventional C57BL/6 mice were fed a semisynthetic diet supplemented with the SQDG rich Spirulina (SD) or a Spirulina free control diet (CD). During the intervention, body weight, water and food intake were monitored and fecal samples were collected. After three weeks, mice were killed and organ weight and size were measured, intestinal sulfonate concentrations were quantified, gut microbiota composition was determined and parameters of intestinal and hepatic fat metabolism were analyzed. Human fecal slurries converted taurine, isethionate, cysteate, 3 sulfolacate, SQ and DHPS to H2S. However, inter individual differences in the degradation of these sulfonates were observed. Taurine, isethionate, and 3 sulfolactate were utilized by fecal microbiota of all donors, while SQ, DHPS and cysteate were converted to H2S only by microbiota from certain individuals. Bacterial isolates from human feces able to convert sulfonates to H2S were identified as taurine-utilizing Desulfovibrio strains, taurine- and isethionate-utilizing B. wadsworthia, or as SQ- and 3-sulfolactate- utilizing E. coli. In addition, a co culture of E. coli and B. wadsworthia led to complete degradation of SQ to H2S, with DHPS as an intermediate. Of the human fecal isolates, B. wadsworthia and Desulfovibrio are potentially harmful. E. coli strains might be also pathogenic, but isolated E. coli strains from human feces were identified as commensal gut bacteria. Feeding SD to mice increased the cecal and fecal SQ concentration and altered the microbiota composition, but the relative abundance of SQDG or SQ converting bacteria and colitogenic bacteria was not enriched in mice fed SD for 21 days. SD did not affect the relative abundance of Enterobacteriaceae, to which the SQDG- and SQ-utilizing E. coli strain belong to. Furthermore, the abundance of B. wadsworthia decreased from day 2 to day 9 in feces, but recovered afterwards in the same mice. In cecum, the family Desulfovibrionaceae, to which B. wadsworthia and Desulfovibrio belong to, were reduced. No changes in the number of B. wadsworthia in cecal contents or of Desulfovibrionaceae in feces were observed. SD led to a mild activation of the immune system, which was not observed in control mice fed CD. Mice fed SD had an increased body weight, a higher adipose tissue weight, and a decreased liver weight compared to the control mice, suggesting an impact of Spirulina supplementation on fat metabolism. However, expression levels of genes involved in intestinal and hepatic intracellular lipid uptake and availability were reduced. Further investigations on the lipid metabolism at protein level could help to clarify these discrepancies. In summary, humans differ in the ability of their fecal microbiota to utilize dietary sulfonates. While sulfonates stimulated the proliferation of potentially colitogenic isolates from human fecal slurries, the increased availability of SQ in Spirulina fed conventional mice did not lead to an enrichment of such bacteria. Presence or absence of these bacteria may explain the inter individual differences in sulfonate conversion observed for fecal slurries. This work provides new insights in the ability of intestinal bacteria to utilize sulfonates and thus, contributes to a better understanding of microbiota-mediated effects on dietary sulfonate utilization. Interestingly, feeding of the Spirulina-supplemented diet led to body-weight gain in mice in the first two days of intervention, the reasons for which are unknown.}, language = {en} } @phdthesis{Grimmer2022, author = {Grimmer, Benjamin}, title = {Pannexin 1}, school = {Universit{\"a}t Potsdam}, pages = {66, XXIX}, year = {2022}, abstract = {Hypoxic pulmonary vasoconstriction is an active alveolar hypoxia-caused physiological response redirecting pulmonary blood flow from poorly ventilated areas to better oxygenated lung regions in order to optimize oxygen supply. However, the signaling pathways underlying this pulmonary vascular response remain an area under investigation. In the present study I investigated the functional relevance of Pannexin 1 (Panx1)-mediated ATP release in hypoxic pulmonary vasoconstriction and chronic hypoxic pulmonary hypertension using murine isolated perfused lungs, chronic hypoxic mice, and pulmonary artery smooth muscle cell culture. In isolated mouse lungs, switch to hypoxic gas induced a marked increase in pulmonary artery pressure. Pharmacological inhibition of Panx1 using probenecid, Panx1 specific inhibitory peptide (10Panx1) or spironolactone as well as genetic deletion of Panx1 in smooth muscle cells diminished hypoxic pulmonary vasoconstriction in isolated perfused mouse lungs. Fura-2 imaging revealed a reduced Ca2+ response to hypoxia in pulmonary artery smooth muscle cells treated with spironolactone or 10Panx1. Although these findings suggested an important role of Panx1 in HPV, neither smooth muscle cell nor endothelial cell specific genetic deletion of Panx1 prevented the development of pulmonary hypertension in chronic hypoxic mice. Surprisingly, hypoxia did not induce ATP release and inhibition of purinergic receptors or ATP degradation by ATPase failed to decrease the pulmonary vasoconstriction response to hypoxia in isolated perfused mouse lungs. However, Panx1 antagonism as well as TRPV4 inhibition prevented the hypoxia-induced increase in intracellular Ca2+ concentration in pulmonary artery smooth muscle cells in an additive manner suggesting that Panx1 might modulate intracellular Ca2+ signaling independently of the ATP-P2-TRPV4 signaling axis. In line with this assumption, overexpression of Panx1 in HeLa cells increased intracellular Ca2+ concentrations in response to acute hypoxia. Conclusion: In this study I identifiy Panx1 as novel regulator of HPV.. Yet, the role of Panx1 was not attributable to the release of ATP and downstream P2 signaling pathways or activation of TRPV4 but rathter relates to a role of Panx1 as indirect or direct modulator of the Ca2+ response to hypoxia in PASMCs. Genetic deletion of Panx1 did not influence the development of chronic hypoxic pulmonary hypertension in mice.}, language = {en} } @phdthesis{Schell2022, author = {Schell, Mareike}, title = {Investigating the effect of Lactobacillus rhamnosus GG on emotional behavior in diet-induced obese C57BL/6N mice}, school = {Universit{\"a}t Potsdam}, pages = {XVI, 117}, year = {2022}, abstract = {The prevalence of depression and anxiety is increased in obese patients compared to healthy humans, which is partially due to a shared pathogenesis, including insulin resistance and inflammation. These factors are also linked to intestinal dysbiosis. Additionally, the chronic consumption of diets rich in saturated fats results in body weight gain, hormonal resistances and unfavorable changes in the microbiome composition. The intake of Lactobacilli has already been shown to improve dysbiosis along with metabolism and mood. Yet, the beneficial role and the underlying mechanism of Lactobacillus rhamnosus GG (LGG) to improve emotional behavior in established diet-induced obese conditions are, so far, unknown. To characterize the role of LGG in diet-induced obesity, female and male C57BL/6N mice were fed a semi-synthetic low-fat diet (LFD, 10 \% kcal from fat) or a conventional high-fat diet (HFD, 45 \% kcal from fat) for initial 6 weeks, which was followed by daily oral gavage of vehicle or 1x10^8 CFU of LGG until the end of the experiment. Mice were subjected to basic metabolic and extensive behavioral phenotyping, with a focus on emotional behavior. Moreover, composition of cecal gut microbiome, metabolomic profile in plasma and cerebrospinal fluid was investigated and followed by molecular analyses. Both HFD-feeding and LGG application resulted in sex-specific differences. While LGG prevented the increase of plasma insulin, adrenal gland weight and hyperactivity in diet-induced obese female mice, there was no regulation of anxiodepressive-like behavior. In contrast, metabolism of male mice did not benefit from LGG application, but strikingly, LGG decreased specifically depressive-like behavior in the Mousetail Suspension Test which was confirmed by the Splash Test characterizing motivation for 'self-care'. The microbiome analysis in male mice revealed that HFD-feeding, but not LGG application, altered cecal microbiome composition, indicating a direct effect of LGG on behavioral regulation. However, in female mice, both HFD-feeding and LGG application resulted in changes of microbiome composition, which presumably affected metabolism. Moreover, as diet-induced obese female mice unexpectedly did not exhibit anxiodepressive-like behavior, follow-up analyses were conducted in male mice. Here, HFD-feeding significantly altered abundance of plasma lipids whereas LGG decreased branched chain amino acids which associated with improved emotional behavior. In nucleus accumbens (NAcc) and VTA/SN, which belong to the dopaminergic system, LGG restored HFD-induced decrease of tyrosine hydroxylase, the rate-limiting enzyme in dopamine synthesis, on gene expression level. Lastly, transcriptome analysis in the NAcc identified gene expression of cholecystokinin as a potential mediator of the effect of LGG on HFD-induced emotional alterations. In summary, this thesis revealed the beneficial effects of LGG application on emotional alterations in established diet-induced obesity. Furthermore, both HFD-feeding and LGG treatment exhibited sex-specific effects, resulting in metabolic improvements in female mice while LGG application mitigated depressive-like behavior in obese male mice along with a molecular signature of restored dopamine synthesis and neuropeptide signaling.}, language = {en} } @phdthesis{Knoche2022, author = {Knoche, Lisa}, title = {Untersuchung von Transformationsprodukten ausgew{\"a}hlter Tierarzneimittel generiert durch Elektrochemie, Mikrosomal Assay, Hydrolyse und Photolyse}, pages = {163, III}, year = {2022}, abstract = {The knowledge of transformation pathways and transformation products of veterinary drugs is important for health, food and environmental matters. Residues, consisting of original veterinary drug and transformation products, are found in food products of animal origin as well as the environment (e.g., soil or surface water). Several transformation processes can alter the original veterinary drug, ranging from biotransformation in living organism to environmental degradation processes like photolysis, hydrolysis, or microbial processes. In this thesis, four veterinary drugs were investigated, three ionophore antibiotics Monensin, Salinomycin and Lasalocid and the macrocyclic lactone Moxidectin. Ionophore antibiotics are mainly used to cure and prevent coccidiosis in poultry especially prophylactic in broiler farming. Moxidectin is an antiparasitic drug that is used for the treatment of internal and external parasites in food-producing and companion animals. The main objective of this work is to employ different laboratory approaches to generate and identify transformation products. The identification was conducted using high-resolution mass spectrometry (HRMS). A major focus was placed on the application of electrochemistry for simulation of transformation processes. The electrochemical reactor - equipped with a three-electrode flow-through cell - enabled the oxidation or reduction by applying a potential. The transformation products derived were analyzed by online coupling of the electrochemical reactor and a HRMS and offline by liquid chromatography (LC) combined with HRMS. The main modification reaction of the identified transformation products differed for each investigated veterinary drug. Monensin showed decarboxylation and demethylation as the main modification reactions, for Salinomycin mostly decarbonylation occurred and for Lasalocid methylation was prevalent. For Moxidectin, I observed an oxidation (hydroxylation) reaction and adduct formation with solvent. In general, for Salinomycin and Lasalocid, more transient transformation products (online measurement) than stable transformation products (offline measurements) were detected. By contrast, the number of transformation products using online and offline measurements were identical for Monensin and Moxidectin. As a complementary approach, metabolism tests with rat or human liver microsomes were conducted for the ionophore antibiotics. Monensin was investigated by using rat liver microsomes and the transformation products identified were based on decarboxylation and demethylation. Salinomycin and Lasalocid were converted by human and rat liver microsomes. For both substances, more transformation products were found by using human liver microsomes. The transformation products of the rat liver microsome conversion were redundant, and the transformation products were also found at the human liver microsome assay. Oxidation (hydroxylation) was found to be the main modification reaction for both. In addition, a frequent ion exchange between sodium and potassium was identified. The final two experiments were performed for one substance each, whereby the hydrolysis of Monensin and the photolysis of Moxidectin was investigated. The transformation products of the pH-dependent hydrolysis were based on ring-opening and dehydration. Moxidectin formed several transformation products by irradiation with UV-C light and the main modification reactions were isomeric changes, (de-)hydration and changes of the methoxime moiety. In summary, transformation products of the four investigated veterinary drugs were generated by the different laboratory approaches. Most of the transformation products were identified for the first time. The resulting findings provide an improved understanding of clarifying the transformation behavior.}, language = {en} } @phdthesis{Bishop2022, author = {Bishop, Christopher Allen}, title = {Influence of dairy intake on odd-chain fatty acids and energy metabolism}, doi = {10.25932/publishup-56154}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-561541}, school = {Universit{\"a}t Potsdam}, pages = {xii, 104, xv}, year = {2022}, abstract = {As of late, epidemiological studies have highlighted a strong association of dairy intake with lower disease risk, and similarly with an increased amount of odd-chain fatty acids (OCFA). While the OCFA also demonstrate inverse associations with disease incidence, the direct dietary sources and mode of action of the OCFA remain poorly understood. The overall aim of this thesis was to determine the impact of two main fractions of dairy, milk fat and milk protein, on OCFA levels and their influence on health outcomes under high-fat (HF) diet conditions. Both fractions represent viable sources of OCFA, as milk fats contain a significant amount of OCFA and milk proteins are high in branched chain amino acids (BCAA), namely valine (Val) and isoleucine (Ile), which can produce propionyl-CoA (Pr-CoA), a precursor for endogenous OCFA synthesis, while leucine (Leu) does not. Additionally, this project sought to clarify the specific metabolic effects of the OCFA heptadecanoic acid (C17:0). Both short-term and long-term feeding studies were performed using male C57BL/6JRj mice fed HF diets supplemented with milk fat or C17:0, as well as milk protein or individual BCAA (Val; Leu) to determine their influences on OCFA and metabolic health. Short-term feeding revealed that both milk fractions induce OCFA in vivo, and the increases elicited by milk protein could be, in part, explained by Val intake. In vitro studies using primary hepatocytes further showed an induction of OCFA after Val treatment via de novo lipogenesis and increased α-oxidation. In the long-term studies, both milk fat and milk protein increased hepatic and circulating OCFA levels; however, only milk protein elicited protective effects on adiposity and hepatic fat accumulation—likely mediated by the anti-obesogenic effects of an increased Leu intake. In contrast, Val feeding did not increase OCFA levels nor improve obesity, but rather resulted in glucotoxicity-induced insulin resistance in skeletal muscle mediated by its metabolite 3-hydroxyisobutyrate (3-HIB). Finally, while OCFA levels correlated with improved health outcomes, C17:0 produced negligible effects in preventing HF-diet induced health impairments. The results presented herein demonstrate that the beneficial health outcomes associated with dairy intake are likely mediated through the effects of milk protein, while OCFA levels are likely a mere association and do not play a significant causal role in metabolic health under HF conditions. Furthermore, the highly divergent metabolic effects of the two BCAA, Leu and Val, unraveled herein highlight the importance of protein quality.}, language = {en} } @phdthesis{Polemiti2022, author = {Polemiti, Elli}, title = {Identifying risk of microvascular and macrovascular complications of type 2 diabetes}, doi = {10.25932/publishup-57103}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-571038}, school = {Universit{\"a}t Potsdam}, pages = {xii, 292}, year = {2022}, abstract = {Diabetes is hallmarked by high blood glucose levels, which cause progressive generalised vascular damage, leading to microvascular and macrovascular complications. Diabetes-related complications cause severe and prolonged morbidity and are a major cause of mortality among people with diabetes. Despite increasing attention to risk factors of type 2 diabetes, existing evidence is scarce or inconclusive regarding vascular complications and research investigating both micro- and macrovascular complications is lacking. This thesis aims to contribute to current knowledge by identifying risk factors - mainly related to lifestyle - of vascular complications, addressing methodological limitations of previous literature and providing comparative data between micro- and macrovascular complications. To address this overall aim, three specific objectives were set. The first was to investigate the effects of diabetes complication burden and lifestyle-related risk factors on the incidence of (further) complications. Studies suggest that diabetes complications are interrelated. However, they have been studied mainly independently of individuals' complication burden. A five-state time-to-event model was constructed to examine the longitudinal patterns of micro- (kidney disease, neuropathy and retinopathy) and macrovascular complications (myocardial infarction and stroke) and their association with the occurrence of subsequent complications. Applying the same model, the effect of modifiable lifestyle factors, assessed alone and in combination with complication load, on the incidence of diabetes complications was studied. The selected lifestyle factors were body mass index (BMI), waist circumference, smoking status, physical activity, and intake of coffee, red meat, whole grains, and alcohol. Analyses were conducted in a cohort of 1199 participants with incident type 2 diabetes from the European Prospective Investigation into Cancer and Nutrition (EPIC)-Potsdam, who were free of vascular complications at diabetes diagnosis. During a median follow-up time of 11.6 years, 96 cases of macrovascular complications (myocardial infarction and stroke) and 383 microvascular complications (kidney disease, neuropathy and retinopathy) were identified. In multivariable-adjusted models, the occurrence of a microvascular complication was associated with a higher incidence of further micro- (Hazard ratio [HR] 1.90; 95\% Confidence interval [CI] 0.90, 3.98) and macrovascular complications (HR 4.72; 95\% CI 1.25, 17.68), compared with persons without a complication burden. In addition, participants who developed a macrovascular event had a twofold higher risk of future microvascular complications (HR 2.26; 95\% CI 1.05, 4.86). The models were adjusted for age, sex, state duration, education, lifestyle, glucose-lowering medication, and pre-existing conditions of hypertension and dyslipidaemia. Smoking was positively associated with macrovascular disease, while an inverse association was observed with higher coffee intake. Whole grain and alcohol intake were inversely associated with microvascular complications, and a U-shaped association was observed for red meat intake. BMI and waist circumference were positively associated with microvascular events. The associations between lifestyle factors and incidence of complications were not modified by concurrent complication burden, except for red meat intake and smoking status, where the associations were attenuated among individuals with a previous complication. The second objective was to perform an in-depth investigation of the association between BMI and BMI change and risk of micro- and macrovascular complications. There is an ongoing debate on the association between obesity and risk of macrovascular and microvascular outcomes in type 2 diabetes, with studies suggesting a protective effect among people with overweight or obesity. These findings, however, might be limited due to suboptimal control for smoking, pre-existing chronic disease, or short-follow-up. After additional exclusion of persons with cancer history at diabetes onset, the associations between pre-diagnosis BMI and relative annual change between pre- and post-diagnosis BMI and incidence of complications were evaluated in multivariable-adjusted Cox models. The analyses were adjusted for age, sex, education, smoking status and duration, physical activity, alcohol consumption, adherence to the Mediterranean diet, and family history of diabetes and cardiovascular disease (CVD). Among 1083 EPIC-Potsdam participants, 85 macrovascular and 347 microvascular complications were identified during a median follow-up period of 10.8 years. Higher pre-diagnosis BMI was associated with an increased risk of total microvascular complications (HR per 5 kg/m2 1.21; 95\% CI 1.07, 1.36), kidney disease (HR 1.39; 95\% CI 1.21, 1.60) and neuropathy (HR 1.12; 95\% CI 0.96, 1.31); but no association was observed for macrovascular complications (HR 1.05; 95\% CI 0.81, 1.36). Effect modification was not evident by sex, smoking status, or age groups. In analyses according to BMI change categories, BMI loss of more than 1\% indicated a decreased risk of total microvascular complications (HR 0.62; 95\% CI 0.47, 0.80), kidney disease (HR 0.57; 95\% CI 0.40, 0.81) and neuropathy (HR 0.73; 95\% CI 0.52, 1.03), compared with participants with a stable BMI. No clear association was observed for macrovascular complications (HR 1.04; 95\% CI 0.62, 1.74). The impact of BMI gain on diabetes-related vascular disease was less evident. Associations were consistent across strata of age, sex, pre-diagnosis BMI, or medication but appeared stronger among never-smokers than current or former smokers. The last objective was to evaluate whether individuals with a high-risk profile for diabetes and cardiovascular disease (CVD) also have a greater risk of complications. Within the EPIC-Potsdam study, two accurate prognostic tools were developed, the German Diabetes Risk Score (GDRS) and the CVD Risk Score (CVDRS), which predict the 5-year type 2 diabetes risk and 10-year CVD risk, respectively. Both scores provide a non-clinical and clinical version. Components of the risk scores include age, sex, waist circumference, prevalence of hypertension, family history of diabetes or CVD, lifestyle factors, and clinical factors (only in clinical versions). The association of the risk scores with diabetes complications and their discriminatory performance for complications were assessed. In crude Cox models, both versions of GDRS and CVDRS were positively associated with macrovascular complications and total microvascular complications, kidney disease and neuropathy. Higher GDRS was also associated with an elevated risk of retinopathy. The discrimination of the scores (clinical and non-clinical) was poor for all complications, with the C-index ranging from 0.58 to 0.66 for macrovascular complications and from 0.60 to 0.62 for microvascular complications. In conclusion, this work illustrates that the risk of complication development among individuals with type 2 diabetes is related to the existing complication load, and attention should be given to regular monitoring for future complications. It underlines the importance of weight management and adherence to healthy lifestyle behaviours, including high intake of whole grains, moderation in red meat and alcohol consumption and avoidance of smoking to prevent major diabetes-associated complications, regardless of complication burden. Risk scores predictive for type 2 diabetes and CVD were related to elevated risks of complications. By optimising several lifestyle and clinical factors, the risk score can be improved and may assist in lowering complication risk.}, language = {en} } @phdthesis{FigueroaCampos2022, author = {Figueroa Campos, Gustavo Adolfo}, title = {Wet-coffee processing production wastes}, doi = {10.25932/publishup-55882}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-558828}, school = {Universit{\"a}t Potsdam}, pages = {X, 159}, year = {2022}, abstract = {Countries processing raw coffee beans are burdened with low economical incomes to fight the serious environmental problems caused by the by-products and wastewater that is generated during the wet-coffee processing. The aim of this work was to develop alternative methods of improving the waste by-product quality and thus making the process economically more attractive with valorization options that can be brought to the coffee producers. The type of processing influences not only the constitution of green coffee but also of by-products and wastewater. Therefore, coffee bean samples as well as by-products and wastewater collected at different production steps of were analyzed. Results show that the composition of wastewater is dependent on how much and how often the wastewater is recycled in the processing. Considering the coffee beans, results indicate that the proteins might be affected during processing and a positive effect of the fermentation on the solubility and accessibility of proteins seems to be probable. The steps of coffee processing influence the different constituents of green coffee beans which, during roasting, give rise to aroma compounds and express the characteristics of roasted coffee beans. Knowing that this group of compounds is involved in the Maillard reaction during roasting, this possibility could be utilized for the coffee producers to improve the quality of green coffee beans and finally the coffee cup quality. The valorization of coffee wastes through modification to activated carbon has been considered as a low-cost option creating an adsorbent with prospective to compete with commercial carbons. Activation protocol using spent coffee and parchment was developed and prepared to assess their adsorption capacity for organic compounds. Spent coffee grounds and parchment proved to have similar adsorption efficiency to commercial activated carbon. The results of this study document a significant information originating from the processing of the de-pulped to green coffee beans. Furthermore, it showed that coffee parchment and spent coffee grounds can be valorized as low-cost option to produce activated carbons. Further work needs to be directed to the optimization of the activation methods to improve the quality of the materials produced and the viability of applying such experiments in-situ to bring the coffee producer further valorization opportunities with environmental perspectives. Coffee producers would profit in establishing appropriate simple technologies to improve green coffee quality, re-use coffee by-products, and wastewater valorization.}, language = {en} } @phdthesis{IgualGil2022, author = {Igual Gil, Carla}, title = {Role of the GDF15-GFRAL pathway under skeletal muscle mitochondrial stress}, doi = {10.25932/publishup-55469}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-554693}, school = {Universit{\"a}t Potsdam}, pages = {IXIII, 73, XVII}, year = {2022}, abstract = {Growth differentiation factor 15 (GDF15) is a stress-induced cytokine secreted into the circulation by a number of tissues under different pathological conditions such as cardiovascular disease, cancer or mitochondrial dysfunction, among others. While GDF15 signaling through its recently identified hindbrain-specific receptor GDNF family receptor alpha-like (GFRAL) has been proposed to be involved in the metabolic stress response, its endocrine role under chronic stress conditions is still poorly understood. Mitochondrial dysfunction is characterized by the impairment of oxidative phosphorylation (OXPHOS), leading to inefficient functioning of mitochondria and consequently, to mitochondrial stress. Importantly, mitochondrial dysfunction is among the pathologies to most robustly induce GDF15 as a cytokine in the circulation. The overall aim of this thesis was to elucidate the role of the GDF15-GFRAL pathway under mitochondrial stress conditions. For this purpose, a mouse model of skeletal muscle-specific mitochondrial stress achieved by ectopic expression of uncoupling protein 1 (UCP1), the HSA-Ucp1-transgenic (TG) mouse, was employed. As a consequence of mitochondrial stress, TG mice display a metabolic remodeling consisting of a lean phenotype, an improved glucose metabolism, an increased metabolic flexibility and a metabolic activation of white adipose tissue. Making use of TG mice crossed with whole body Gdf15-knockout (GdKO) and Gfral-knockout (GfKO) mouse models, this thesis demonstrates that skeletal muscle mitochondrial stress induces the integrated stress response (ISR) and GDF15 in skeletal muscle, which is released into the circulation as a myokine (muscle-induced cytokine) in a circadian manner. Further, this work identifies GDF15-GFRAL signaling to be responsible for the systemic metabolic remodeling elicited by mitochondrial stress in TG mice. Moreover, this study reveals a daytime-restricted anorexia induced by the GDF15-GFRAL axis under muscle mitochondrial stress, which is, mechanistically, mediated through the induction of hypothalamic corticotropin releasing hormone (CRH). Finally, this work elucidates a so far unknown physiological outcome of the GDF15-GFRAL pathway: the induction of anxiety-like behavior. In conclusion, this study uncovers a muscle-brain crosstalk under skeletal muscle mitochondrial stress conditions through the induction of GDF15 as a myokine that signals through the hindbrain-specific GFRAL receptor to elicit a stress response leading to metabolic remodeling and modulation of ingestive- and anxiety-like behavior.}, language = {en} } @phdthesis{Baeseler2021, author = {Baeseler, Jessica}, title = {Trace element effects on longevity and neurodegeneration with focus on C. elegans}, school = {Universit{\"a}t Potsdam}, pages = {X,114,VIII}, year = {2021}, abstract = {The trace elements zinc and manganese are essential for human health, especially due to their enzymatic and protein stabilizing functions. If these elements are ingested in amounts exceeding the requirements, regulatory processes for maintaining their physiological concentrations (homeostasis) can be disturbed. Those homeostatic dysregulations can cause severe health effects including the emergence of neurodegenerative disorders such as Parkinson's disease (PD). The concentrations of essential trace elements also change during the aging process. However, the relations of cause and consequence between increased manganese and zinc uptake and its influence on the aging process and the emergence of the aging-associated PD are still rarely understood. This doctoral thesis therefore aimed to investigate the influence of a nutritive zinc and/or manganese oversupply on the metal homeostasis during the aging process. For that, the model organism Caenorhabditis elegans (C. elegans) was applied. This nematode suits well as an aging and PD model due to properties such as its short life cycle and its completely sequenced, genetically amenable genome. Different protocols for the propagation of zinc- and/or manganese-supplemented young, middle-aged and aged C. elegans were established. Therefore, wildtypes, as well as genetically modified worm strains modeling inheritable forms of parkinsonism were applied. To identify homeostatic and neurological alterations, the nematodes were investigated with different methods including the analysis of total metal contents via inductively-coupled plasma tandem mass spectrometry, a specific probe-based method for quantifying labile zinc, survival assays, gene expression analysis as well as fluorescence microscopy for the identification and quantification of dopaminergic neurodegeneration.. During aging, the levels of iron, as well as zinc and manganese increased.. Furthermore, the simultaneous oversupply with zinc and manganese increased the total zinc and manganese contents to a higher extend than the single metal supplementation. In this relation the C. elegans metallothionein 1 (MTL-1) was identified as an important regulator of metal homeostasis. The total zinc content and the concentration of labile zinc were age-dependently, but differently regulated. This elucidates the importance of distinguishing these parameters as two independent biomarkers for the zinc status. Not the metal oversupply, but aging increased the levels of dopaminergic neurodegeneration. Additionally, nearly all these results yielded differences in the aging-dependent regulation of trace element homeostasis between wildtypes and PD models. This confirms that an increased zinc and manganese intake can influence the aging process as well as parkinsonism by altering homeostasis although the underlying mechanisms need to be clarified in further studies.}, language = {en} } @phdthesis{Alfine2021, author = {Alfine, Eugenia}, title = {Investigation of Sirtuin 3 overexpression as a genetic model of fasting in hypothalamic neurons}, school = {Universit{\"a}t Potsdam}, pages = {134}, year = {2021}, language = {en} } @phdthesis{Reichmann2021, author = {Reichmann, Robin}, title = {Novel applications of machine learning techniques in epidemiology of age-related diseases}, school = {Universit{\"a}t Potsdam}, pages = {164, xlv}, year = {2021}, language = {en} } @phdthesis{Herpich2021, author = {Herpich, Catrin}, title = {Fibroblast growth factor 21 and its association with nutritional stimuli in older age}, school = {Universit{\"a}t Potsdam}, pages = {75}, year = {2021}, abstract = {Fibroblast growth differentiation factor 21 (FGF21) is known as a pivotal regulator of the glucose and lipid metabolism. As such, it is considered beneficial and has even been labelled a longevity hormone. Nevertheless, recent observational studies have shown that FGF21 is increased in higher age with possible negative effects such as loss of lean and bone mass as well as decreased survival. Hepatic FGF21 secretion can be induced by various nutritional stimuli such as starvation, high carbohydrate and fat intake as well as protein deficiency.. So far it is still unclear whether the FGF21 response to different macronutrients is altered in older age. An altered response would potentially contribute to explain the higher FGF21 concentrations found in older age. In this publication-based doctoral dissertation, a cross-sectional study as well as a dietary challenge were conducted to investigate the influence of nutrition on FGF21 concentrations and response in older age. In a cross-sectional study, FGF21 concentrations were assessed in older patients with and without cachexia anorexia syndrome anorexia syndrome compared to an older community-dwelling control group. Cachexia anorexia syndrome is a multifactorial syndrome frequently occurring in old age or in the context of an underlying disease. It is characterized by a severe involuntary weight loss, loss of appetite (anorexia) and reduced food intake, therefore representing a state of severe nutrient deficiency, in some aspects similar to starvation. The highest FGF21 concentrations were found in patients with cachexia anorexia syndrome. Moreover, FGF21 was positively correlated with weight loss and loss of appetite. In addition, cachexia anorexia syndrome itself was associated with FGF21 independent of sex, age and body mass index. As cachectic patients presumably exhibit protein malnutrition and FGF21 has been proposed a marker for protein insufficiency, the higher levels of FGF21 in patients with cachexia anorexia syndrome might be partly explained by insufficient protein intake. In order to investigate the acute response of FGF21 to different nutritional stimuli, a dietary challenge with a parallel group design was conducted. Here, healthy older (65-85 years) and younger (18-35 years) adults were randomized to one of four test meals: a dextrose drink, a high carbohydrate, high fat or high protein meal. Over the course of four hours, postprandial FGF21 concentrations (dynamics) were assessed and the FGF21 response (incremental area under the curve) to each test meal was examined.. In a sub-group of older and younger women, also the adiponectin response was investigated, as adiponectin is a known mediator of FGF21 effects on glucose and lipid metabolism. The dietary meal challenge revealed that dextrose and high carbohydrate intake result in higher FGF21 concentrations after four hours in older adults. This was partly explained by higher postprandial glucose concentrations in the old. For high fat ingestion no age differences were found. For the first time, acute FGF21 response to high protein intake was shown. Here, protein ingestion resulted in lower FGF21 concentrations in younger compared to older adults. Furthermore, sufficient protein intake, according to age-dependent recommendations, of the previous day, was associated with lower FGF21 concentrations in both age groups. The higher FGF21 response to dextrose ingestion resulted in a higher adiponectin response in older women, independent of fat mass, insulin resistance, triglyceride concentrations, inflammation and oxidative stress. Following the high fat meal, adiponectin concentrations declined in older women. Adiponectin response was not affected by meal composition in younger women. In summary, this thesis showed a positive association of FGF21 and cachexia anorexia syndrome with concomitant anorexia in older patients. Regarding the acute FGF21 response, a higher response following dextrose and carbohydrate ingestion was found in older compared with younger subjects. This might be attributed to a higher glucose response in older age. Furthermore, it was shown that the higher FGF21 response after dextrose ingestion possibly contributes to a higher adiponectin response in older women, independent of potential metabolic and inflammatory confounders. Acute protein ingestion resulted in a significant decrease in FGF21 concentrations. Moreover, protein intake of the previous day was inversely associated with fasting FGF21 concentrations. This might explain why FGF21 concentrations are higher in cachexia anorexia syndrome. These results therefore support the role of FGF21 as a sensor of protein restriction.}, language = {en} } @phdthesis{Hauffe2021, author = {Hauffe, Robert}, title = {Investigating metabolic consequences of an HSP60 reduction during diet-induced obesity}, doi = {10.25932/publishup-50929}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-509294}, school = {Universit{\"a}t Potsdam}, pages = {xxi, 116}, year = {2021}, abstract = {The mitochondrial chaperone complex HSP60/HSP10 facilitates mitochondrial protein homeostasis by folding more than 300 mitochondrial matrix proteins. It has been shown previously that HSP60 is downregulated in brains of type 2 diabetic (T2D) mice and patients, causing mitochondrial dysfunction and insulin resistance. As HSP60 is also decreased in peripheral tissues in T2D animals, this thesis investigated the effect of overall reduced HSP60 in the development of obesity and associated co-morbidities. To this end, both female and male C57Bl/6N control (i.e. without further alterations in their genome, Ctrl) and heterozygous whole-body Hsp60 knock-out (Hsp60+/-) mice, which exhibit a 50 \% reduction of HSP60 in all tissues, were fed a normal chow diet (NCD) or a highfat diet (HFD, 60 \% calories from fat) for 16 weeks and were subjected to extensive metabolic phenotyping including indirect calorimetry, NMR spectroscopy, insulin, glucose and pyruvate tolerance tests, vena cava insulin injections, as well as histological and molecular analysis. Interestingly, NCD feeding did not result in any striking phenotype, only a mild increase in energy expenditure in Hsp60+/- mice. Exposing mice to a HFD however revealed an increased body weight due to higher muscle mass in female Hsp60+/- mice, with a simultaneous decrease in energy expenditure. Additionally, these mice displayed decreased fasting glycemia. Opposingly, male Hsp60+/- compared to control mice showed lower body weight gain due to decreased fat mass and an increased energy expenditure, strikingly independent of lean mass. Further, only male Hsp60+/- mice display improved HOMA-IR and Matsuda insulin sensitivity indices. Despite the opposite phenotype in regards to body weight development, Hsp60+/- mice of both sexes show a significantly higher cell number, as well as a reduction in adipocyte size in the subcutaneous and gonadal white adipose tissue (sc/gWAT). Curiously, this adipocyte hyperplasia - usually associated with positive aspects of WAT function - is disconnected from metabolic improvements, as the gWAT of male Hsp60+/- mice shows mitochondrial dysfunction, oxidative stress, and insulin resistance. Transcriptomic analysis of gWAT shows an up regulation of genes involved in macroautophagy. Confirmatory, expression of microtubuleassociated protein 1A/1B light chain 3B (LC3), as a protein marker of autophagy, and direct measurement of lysosomal activity is increased in the gWAT of male Hsp60+/- mice. In summary, this thesis revealed a novel gene-nutrient interaction. The reduction of the crucial chaperone HSP60 did not have large effects in mice fed a NCD, but impacted metabolism during DIO in a sex-specific manner, where, despite opposing body weight and body composition phenotypes, both female and male Hsp60+/- mice show signs of protection from high fat diet-induced systemic insulin resistance.}, language = {en} } @phdthesis{Mancini2021, author = {Mancini, Carola}, title = {Analysis of the effects of age-related changes of metabolic flux on brown adipocyte formation and function}, doi = {10.25932/publishup-51266}, school = {Universit{\"a}t Potsdam}, pages = {xvii, 134}, year = {2021}, abstract = {Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis, thereby allowing mammals to maintain a constant body temperature in a cold environment. Thermogenic capacity of this tissue is due to a high mitochondrial density and expression of uncoupling protein 1 (UCP1), a unique brown adipocyte marker which dissipates the mitochondrial proton gradient to produce heat instead of ATP. BAT is actively involved in whole-body metabolic homeostasis and during aging there is a loss of classical brown adipose tissue with concomitantly reduced browning capacity of white adipose tissue. Therefore, an age-dependent decrease of BAT-related energy expenditure capacity may exacerbate the development of metabolic diseases, including obesity and type 2 diabetes mellitus. Given that direct effects of age-related changes of BAT-metabolic flux have yet to be unraveled, the aim of the current thesis is to investigate potential metabolic mechanisms involved in BAT-dysfunction during aging and to identify suitable metabolic candidates as functional biomarkers of BAT-aging. To this aim, integration of transcriptomic, metabolomic and proteomic data analyses of BAT from young and aged mice was performed, and a group of candidates with age-related changes was revealed. Metabolomic analysis showed age-dependent alterations of metabolic intermediates involved in energy, nucleotide and vitamin metabolism, with major alterations regarding the purine nucleotide pool. These data suggest a potential role of nucleotide intermediates in age-related BAT defects. In addition, the screening of transcriptomic and proteomic data sets from BAT of young and aged mice allowed identification of a 60-kDa lysophospholipase, also known as L-asparaginase (Aspg), whose expression declines during BAT-aging. Involvement of Aspg in brown adipocyte thermogenic function was subsequently analyzed at the molecular level using in vitro approaches and animal models. The findings revealed sensitivity of Aspg expression to β3-adrenergic activation via different metabolic cues, including cold exposure and treatment with β3-adrenergic agonist CL. To further examine ASPG function in BAT, an over-expression model of Aspg in a brown adipocyte cell line was established and showed that these cells were metabolically more active compared to controls, revealing increased expression of the main brown-adipocyte specific marker UCP1, as well as higher lipolysis rates. An in vitro loss-of-function model of Aspg was also functionally analyzed, revealing reduced brown adipogenic characteristics and an impaired lipolysis, thus confirming physiological relevance of Aspg in brown adipocyte function. Characterization of a transgenic mouse model with whole-body inactivation of the Aspg gene (Aspg-KO) allowed investigation of the role of ASPG under in vivo conditions, indicating a mild obesogenic phenotype, hypertrophic white adipocytes, impairment of the early thermogenic response upon cold-stimulation and dysfunctional insulin sensitivity. Taken together, these data show that ASPG may represent a new functional biomarker of BAT-aging that regulates thermogenesis and therefore a potential target for the treatment of age-related metabolic disease.}, language = {en} } @phdthesis{Schjeide2021, author = {Schjeide, Brit-Maren}, title = {Development and characterization of the MoN-Light BoNT assay to determine the toxicity of botulinum neurotoxin in motor neurons differentiated from CRISPR-modified induced pluripotent stem cells}, doi = {10.25932/publishup-51627}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-516278}, school = {Universit{\"a}t Potsdam}, pages = {e, xviii, 265}, year = {2021}, abstract = {Botulinum neurotoxin (BoNT) is produced by the anaerobic bacterium Clostridium botulinum. It is one of the most potent toxins found in nature and can enter motor neurons (MN) to cleave proteins necessary for neurotransmission, resulting in flaccid paralysis. The toxin has applications in both traditional and esthetic medicine. Since BoNT activity varies between batches despite identical protein concentrations, the activity of each lot must be assessed. The gold standard method is the mouse lethality assay, in which mice are injected with a BoNT dilution series to determine the dose at which half of the animals suffer death from peripheral asphyxia. Ethical concerns surrounding the use of animals in toxicity testing necessitate the creation of alternative model systems to measure the potency of BoNT. Prerequisites of a successful model are that it is human specific; it monitors the complete toxic pathway of BoNT; and it is highly sensitive, at least in the range of the mouse lethality assay. One model system was developed by our group, in which human SIMA neuroblastoma cells were genetically modified to express a reporter protein (GLuc), which is packaged into neurosecretory vesicles, and which, upon cellular depolarization, can be released - or inhibited by BoNT - simultaneously with neurotransmitters. This assay has great potential, but includes the inherent disadvantages that the GLuc sequence was randomly inserted into the genome and the tumor cells only have limited sensitivity and specificity to BoNT. This project aims to improve these deficits, whereby induced pluripotent stem cells (iPSCs) were genetically modified by the CRISPR/Cas9 method to insert the GLuc sequence into the AAVS1 genomic safe harbor locus, precluding genetic disruption through non-specific integrations. Furthermore, GLuc was modified to associate with signal peptides that direct to the lumen of both large dense core vesicles (LDCV), which transport neuropeptides, and synaptic vesicles (SV), which package neurotransmitters. Finally, the modified iPSCs were differentiated into motor neurons (MNs), the true physiological target of BoNT, and hypothetically the most sensitive and specific cells available for the MoN-Light BoNT assay. iPSCs were transfected to incorporate one of three constructs to direct GLuc into LDCVs, one construct to direct GLuc into SVs, and one "no tag" GLuc control construct. The LDCV constructs fused GLuc with the signal peptides for proopiomelanocortin (hPOMC-GLuc), chromogranin-A (CgA-GLuc), and secretogranin II (SgII-GLuc), which are all proteins found in the LDCV lumen. The SV construct comprises a VAMP2-GLuc fusion sequence, exploiting the SV membrane-associated protein synaptobrevin (VAMP2). The no tag GLuc expresses GLuc non-specifically throughout the cell and was created to compare the localization of vesicle-directed GLuc. The clones were characterized to ensure that the GLuc sequence was only incorporated into the AAVS1 safe harbor locus and that the signal peptides directed GLuc to the correct vesicles. The accurate insertion of GLuc was confirmed by PCR with primers flanking the AAVS1 safe harbor locus, capable of simultaneously amplifying wildtype and modified alleles. The PCR amplicons, along with an insert-specific amplicon from candidate clones were Sanger sequenced to confirm the correct genomic region and sequence of the inserted DNA. Off-target integrations were analyzed with the newly developed dc-qcnPCR method, whereby the insert DNA was quantified by qPCR against autosomal and sex-chromosome encoded genes. While the majority of clones had off-target inserts, at least one on-target clone was identified for each construct. Finally, immunofluorescence was utilized to localize GLuc in the selected clones. In iPSCs, the vesicle-directed GLuc should travel through the Golgi apparatus along the neurosecretory pathway, while the no tag GLuc should not follow this pathway. Initial analyses excluded the CgA-GLuc and SgII-GLuc clones due to poor quality protein visualization. The colocalization of GLuc with the Golgi was analyzed by confocal microscopy and quantified. GLuc was strongly colocalized with the Golgi in the hPOMC-GLuc clone (r = 0.85±0.09), moderately in the VAMP2-GLuc clone (r = 0.65±0.01), and, as expected, only weakly in the no tag GLuc clone (r = 0.44±0.10). Confocal microscopy of differentiated MNs was used to analyze the colocalization of GLuc with proteins associated with LDCVs and SVs, SgII in the hPOMC-GLuc clone (r = 0.85±0.08) and synaptophysin in the VAMP2-GLuc clone (r = 0.65±0.07). GLuc was also expressed in the same cells as the MN-associated protein, Islet1. A significant portion of GLuc was found in the correct cell type and compartment. However, in the MoN-Light BoNT assay, the hPOMC-GLuc clone could not be provoked to reliably release GLuc upon cellular depolarization. The depolarization protocol for hPOMC-GLuc must be further optimized to produce reliable and specific release of GLuc upon exposure to a stimulus. On the other hand, the VAMP2-GLuc clone could be provoked to release GLuc upon exposure to the muscarinic and nicotinic agonist carbachol. Furthermore, upon simultaneous exposure to the calcium chelator EGTA, the carbachol-provoked release of GLuc could be significantly repressed, indicating the detection of GLuc was likely associated with vesicular fusion at the presynaptic terminal. The application of the VAMP2-GLuc clone in the MoN-Light BoNT assay must still be verified, but the results thus far indicate that this clone could be appropriate for the application of BoNT toxicity assessment.}, language = {en} } @phdthesis{Saussenthaler2021, author = {Saussenthaler, Sophie}, title = {The impact of DNA methylation on susceptibility to typ 2 diabetes in NZO mice}, school = {Universit{\"a}t Potsdam}, pages = {XIX, 150}, year = {2021}, abstract = {The development of type 2 diabetes (T2D) is driven by genetic as well as life style factors. However, even genetically identical female NZO mice on a high-fat diet show a broad variation in T2D onset. The main objective of this study was to elucidate and investigate early epigenetic determinants of type 2 diabetes. Prior to other experiments, early fat content of the liver (<55.2 HU) in combination with blood glucose concentrations (>8.8 mM) were evaluated as best predictors of diabetes in NZO females. Then, DNA methylome and transcriptome were profiled to identify molecular pathophysiological changes in the liver before diabetes onset. The major finding of this thesis is that alterations in the hepatic DNA methylome precede diabetes onset. Of particular interest were 702 differentially methylated regions (DMRs), of which 506 DMRs had genic localization. These inter-individual DMRs were enriched by fivefold in the KEGG pathway type 2 diabetes mellitus, independent of the level of gene expression, demonstrating an epigenetic predisposition toward diabetes. Interestingly, among the list of hepatic DMRs, eleven DMRs were associated with known imprinted genes in the mouse genome. Thereby, six DMRs (Nap1l5, Mest, Plagl1, Gnas, Grb10 and Slc38a4) localized to imprinting control regions, including five iDMRs that exhibited hypermethylation in livers of diabetes-prone mice. This suggests that gain of DNA methylation in multiple loci of the paternal alleles has unfavourable metabolic consequences for the offspring. Further, the comparative liver transcriptome analysis demonstrated differences in expression levels of 1492 genes related to metabolically relevant pathways, such as citrate cycle and fatty acid metabolism. The integration of hepatic transcriptome and DNA methylome indicated that 449 differentially expressed genes were potentially regulated by DNA methylation, including genes implicated in insulin signaling. In addition, liver transcriptomic profiling of diabetes-resistant and diabetes-prone mice revealed a potential transcriptional dysregulation of 17 hepatokines, in particular Hamp. The hepatic expression of Hamp was decreased by 52\% in diabetes-prone mice, on account of an increase in DNA methylation of promoter CpG-118. Hence, HAMP protein levels were lower in mice prone to develop diabetes, which correlated to higher liver triglyceride levels.. In sum, the identified DNA methylation changes appear to collectively favor the initiation and progression of diabetes in female NZO mice. In near future, epigenetic biomarkers are likely to contribute to improved diagnosis for T2D.}, language = {en} } @phdthesis{Engel2021, author = {Engel, Anika}, title = {Endocrine effects of plasticizers and the development of a breast cell-based toxicity screening system}, doi = {10.25932/publishup-53117}, school = {Universit{\"a}t Potsdam}, pages = {VIII, 89}, year = {2021}, abstract = {Humans are frequently exposed to a variety of endocrine disrupting chemicals (EDCs), which can cause harmful effects, e.g. disturbance of growth, development and reproduction, and cancer (UBA, 2016). EDCs are often components of synthetically manufactured products. Materials made of plastics, building materials, electronic items, textiles or cosmetic products can be particularly contaminated (Ain et al., 2021). One group of EDCs that has gained increased interest in recent years is phthalates. They are used as plasticizers in plastic materials to which people are daily exposed to. Phthalate plasticizers exert their harmful effects among others via activation of the estrogen receptor α (ERα), the estrogen receptor β (ERβ) and via inhibition of the androgen receptor (AR). Some phthalates have already been classified by the EU as Cancerogenic-, Mutagenic-, Reprotoxic- (CMR) substances and their use in industry has been restricted. After oral ingestion, phthalates are metabolized and are finally excreted with the urine. Numerous toxicological studies exist on phthalates, but mainly with the parent substances, not with their primary and secondary metabolites. In the course of the restriction of phthalates by the EU, the phthalate-free plasticizer di-isononylcyclohexane-1,2-dicarboxylate (DINCH®), was introduced to the market. So far, almost no toxicologically relevant properties have been identified for DINCH®. However, the effects of DINCH® have only been studied in animal experiments and, as with phthalates, almost exclusively with the parent substance. However, toxic effects of a particular compound may be induced by its metabolites and not by the parent compound itself. Therefore, potential endocrine effects of 15 phthalates, 19 phthalate metabolites, DINCH®, and five of its metabolites were investigated using reporter gene assays on the ERα, ERβ, and the AR. In addition, studies of the influence of some selected plasticizers on peroxisome proliferator-activated receptor α (PPARα) and peroxisome proliferator-activated receptor γ (PPARγ) activity were performed. Furthermore, a H295R steroidogenesis assay was performed to determine the influence of DINCH® and its metabolites on estradiol or testosterone synthesis. Analysis of the experiments shows that the phthalates either stimulated or inhibited ERα and ERβ activity and inhibited AR activity, whereas the phthalate metabolites did not affect the activity of these human hormone receptors. In contrast, metabolites of di-(2-ethylhexyl) phthalate (DEHP) stimulated transactivation of the human PPARα and PPARγ in analogous reporter gene assays, although DEHP itself did not activate these nuclear receptors. Therefore, primary and secondary phthalate metabolites appear to exert different effects at the molecular level compared to the parent compounds. Similarly, the results showed that the phthalate-free plasticizer DINCH® itself did not affect the activity of ERα, ERβ, AR, PPARα and PPARγ, while the DINCH® metabolites were shown to activate all these receptors. In the case of AR, DINCH® metabolites mainly enhanced AR activity stimulated by dihydrotestosterone (DHT). In the H295R steroidogenesis assay, neither DINCH® nor any of its metabolites affected estradiol or testosterone synthesis. Primary and secondary metabolites of DINCH® thus exert different effects at the molecular level than DINCH® itself. However, all these in vitro effects of DINCH® metabolites were observed only at high concentrations, which were about three orders of magnitude higher than the reported DINCH® metabolite concentrations in human urine. Therefore, the in vitro data does not support the assumption that DINCH® or any of the metabolites studied could have significant endocrine effects in vivo at relevant exposure levels in humans. Following the demonstration of direct and indirect endocrine effects of the studied plasticizers, a new effect-based in vitro 3D screening tool for toxicity assays of non-genotoxic carcinogens was developed using estrogen receptor-negative (ER-) MCF10-A cells and estrogen receptor-positive (ER+) MCF-12A cells. This arose from the background that breast cancer is the most common cancer occurring in women and estrogenic substances, such as phthalates, can probably influence the disease. The human mammary epithelial cell lines MCF-10A and MCF-12A form well-differentiated acini-like structures when cultured in three-dimensional Matrigel culture for a period of 20 days. The model should make it possible to detect substance effects on cell differentiation and growth, on mammary cell acini, and to differentiate between estrogenic and non-estrogenic effects at the same time. In the present study, both cell lines were tested for their suitability as an effect-based in vitro assay system for non-genotoxic carcinogens. An Automated Acinus Detection And Morphological Evaluation (ADAME) software solution has been developed for automatic acquisition of acinus images and determination of morphological parameters such as acinus size, lumen size, and acinus roundness. Several test substances were tested for their ability to affect acinus formation and cellular differentiation. Human epithelial growth factor (EGF) stimulated acinus growth for both cell lines, while all trans retinoic acid (RA) inhibited acinar growth. The potent estrogen 17β-estradiol had no effect on acinus formation of MCF-10A cells but resulted in larger MCF-12A acini. Thus, the parallel use of both cell lines together with the developed high content screening and evaluation tool allows the rapid identification of the estrogenic and cancerogenic properties of a given test compound. The morphogenesis of the acini was only slightly affected by the test substances. On the one hand, this suggests a robust test system, on the other hand, it probably cannot detect low-potent estrogenic compounds such as phthalates or DINCH®. The advantage of the robustness of the system, however, may be that vast numbers of "positive" results with questionable biological relevance could be avoided, such as those observed in sensitive reporter gene assays.}, language = {en} } @phdthesis{Wandt2021, author = {Wandt, Viktoria Klara Veronika}, title = {Trace elements, ageing, and sex}, school = {Universit{\"a}t Potsdam}, pages = {iii, 204}, year = {2021}, language = {en} } @phdthesis{AgaBarfknecht2021, author = {Aga-Barfknecht, Heja}, title = {Investigation of the phenotype and genetic variant(s) of the diabetes locus Nidd/DBA}, school = {Universit{\"a}t Potsdam}, year = {2021}, abstract = {Diabetes is a major public health problem with increasing global prevalence. Type 2 diabetes (T2D), which accounts for 90\% of all diagnosed cases, is a complex polygenic disease also modulated by epigenetics and lifestyle factors. For the identification of T2D-associated genes, linkage analyses combined with mouse breeding strategies and bioinformatic tools were useful in the past. In a previous study in which a backcross population of the lean and diabetes-prone dilute brown non-agouti (DBA) mouse and the obese and diabetes-susceptible New Zealand obese (NZO) mouse was characterized, a major diabetes quantitative trait locus (QTL) was identified on chromosome 4. The locus was designated non-insulin dependent diabetes from DBA (Nidd/DBA). The aim of this thesis was (i) to perform a detailed phenotypic characterization of the Nidd/DBA mice, (ii) to further narrow the critical region and (iii) to identify the responsible genetic variant(s) of the Nidd/DBA locus. The phenotypic characterization of recombinant congenic mice carrying a 13.6 Mbp Nidd/DBA fragment with 284 genes presented a gradually worsening metabolic phenotype. Nidd/DBA allele carriers exhibited severe hyperglycemia (~19.9 mM) and impaired glucose clearance at 12 weeks of age. Ex vivo perifusion experiments with islets of 13-week-old congenic mice revealed a tendency towards reduced insulin secretion in homozygous DBA mice. In addition, 16-week-old mice showed a severe loss of β-cells and reduced pancreatic insulin content. Pathway analysis of transcriptome data from islets of congenic mice pointed towards a downregulation of cell survival genes. Morphological analysis of pancreatic sections displayed a reduced number of bi-hormonal cells co-expressing glucagon and insulin in homozygous DBA mice, which could indicate a reduced plasticity of endocrine cells in response to hyperglycemic stress. Further generation and phenotyping of recombinant congenic mice enabled the isolation of a 3.3 Mbp fragment that was still able to induce hyperglycemia and contained 61 genes. Bioinformatic analyses including haplotype mapping, sequence and transcriptome analysis were integrated in order to further reduce the number of candidate genes and to identify the presumable causative gene variant. Four putative candidate genes (Ttc39a, Kti12, Osbpl9, Calr4) were defined, which were either differentially expressed or carried a sequence variant. In addition, in silico ChIP-Seq analyses of the 3.3 Mbp region indicated a high number of SNPs located in active regions of binding sites of β-cell transcription factors. This points towards potentially altered cis-regulatory elements that could be responsible for the phenotype conferred by the Nidd/DBA locus. In summary, the Nidd/DBA locus mediates impaired glucose homeostasis and reduced insulin secretion capacity which finally leads to β-cell death. The downregulation of cell survival genes and reduced plasticity of endocrine cells could further contribute to the β-cell loss. The critical region was narrowed down to a 3.3 Mbp fragment containing 61 genes, of which four might be involved in the development of the diabetogenic Nidd/DBA phenotype.}, language = {en} } @phdthesis{Burkhardt2021, author = {Burkhardt, Wiebke}, title = {Role of dietary sulfonates in the stimulation of gut bacteria promoting intestinal inflammation}, doi = {10.25932/publishup-51368}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-513685}, school = {Universit{\"a}t Potsdam}, pages = {XX, 79, XXXIX}, year = {2021}, abstract = {The interplay between intestinal microbiota and host has increasingly been recognized as a major factor impacting health. Studies indicate that diet is the most influential determinant affecting the gut microbiota. A diet rich in saturated fat was shown to stimulate the growth of the colitogenic bacterium Bilophila wadsworthia by enhancing the secretion of the bile acid taurocholate (TC). The sulfonated taurine moiety of TC is utilized as a substrate by B. wadsworthia. The resulting overgrowth of B. wadsworthia was accompanied by an increased incidence and severity of colitis in interleukin (IL)-10-deficient mice, which are genetically prone to develop inflammation. Based on these findings, the question arose whether the intake of dietary sulfonates also stimulates the growth of B. wadsworthia and thereby promotes intestinal inflammation in genetically susceptible mice. Dietary sources of sulfonates include green vegetables and cyanobacteria, which contain the sulfolipids sulfoquinovosyl diacylglycerols (SQDG) in considerable amounts. Based on literature reports, the gut commensal Escherichia coli is able to release sulfoquinovose (SQ) from SQDG and in further steps, convert SQ to 2,3-dihydroxypropane-1-sulfonate (DHPS) and dihydroxyacetone phosphate. DHPS may then be utilized as a growth substrate by B. wadsworthia, which results in the formation of sulfide. Both, sulfide formation and a high abundance of B. wadsworthia have been associated with intestinal inflammation. In the present study, conventional IL-10-deficient mice were fed either a diet supplemented with the SQDG-rich cyanobacterium Spirulina (20\%, SD) or a control diet. In addition SQ, TC, or water were orally applied to conventional or gnotobiotic IL-10-deficient mice. The gnotobiotic mice harbored a simplified human intestinal microbiota (SIHUMI) either with or without B. wadsworthia. During the intervention period, the body weight of the mice was monitored, the colon permeability was assessed and fecal samples were collected. After the three-week intervention, the animals were examined with regard to inflammatory parameters, microbiota composition and sulfonate concentrations in different intestinal sites. None of the mice treated with the above-mentioned sulfonates showed weight loss or intestinal inflammation. Solely mice fed SD or gavaged with TC displayed a slight immune response. These mice also displayed an altered microbiota composition, which was not observed in mice gavaged with SQ. The abundance of B. wadsworthia was strongly reduced in mice fed SD, while that of mice treated with SQ or TC was in part slightly increased. The intestinal SQ-concentration was elevated in mice orally treated with SD or SQ, whereas neither TC nor taurine concentrations were consistently elevated in mice gavaged with TC. Additional colonization of SIHUMI mice with B. wadsworthia resulted in a mild inflammatory response, but only in mice treated with TC. In general, TC-mediated effects on the immune system and abundance of B. wadsworthia were not as strong as described in the literature. In summary, neither the tested dietary sulfonates nor TC led to bacteria-induced intestinal inflammation in the IL-10-deficient mouse model, which was consistently observed in both conventional and gnotobiotic mice. For humans, this means that foods containing SQDG, such as spinach or Spirulina, do not increase the risk of intestinal inflammation.}, language = {en} } @phdthesis{Rausch2021, author = {Rausch, Ann-Kristin}, title = {Development of LC-MS/MS Multi-Methods for the Analysis of Contaminants and Residues}, school = {Universit{\"a}t Potsdam}, pages = {IX, 234, v}, year = {2021}, abstract = {Mycotoxins are secondary metabolites produced by several filamentous fungal species, thus occurring ubiquitously in the environment and food. While the heterogeneous group shows differences in their bioavailability and toxicity, the low-molecular-weight xenobiotics are capable of impacting human and animal health acutely and chronically. Therefore, maximum levels for the major mycotoxins in food and feed are regulated in the current European legislation. Besides free mycotoxins, naturally occurring modified mycotoxins are gaining more attention in recent years. Modified mycotoxins constitute toxins altered by plants, microorganisms, and living organisms in different metabolic pathways or food processing steps. The toxicological relevant compounds often co-occur with their free forms in infested food and feed. Thus, the toxins may contribute to the overall toxicity of mycotoxins, wherefore their presence and toxicity should be considered in risk assessment. Until now, however, there are no regulated limits for modified mycotoxins within the European Union. In this thesis, rapid, sensitive, and robust methods for the analysis of mycotoxins and their modified forms were developed and validated using state-of-the-art high performance liquid chromatography tandem mass spectrometry (LC-MS/MS) systems. Firstly, two analytical methods for determining 38 mycotoxins in cereals and 41 mycotoxins in beer were established since agricultural products count as the primary source of mycotoxin contamination. For the analysis of cereal samples, a QuEChERS- based extraction approach was pursued, while analytes from beer samples were extracted using an acetonitrile precipitation scheme. Validation in cereals, namely wheat, corn, rice, and barley, as well as in beer, demonstrated satisfactory results. To obtain information regarding the natural occurrence of mycotoxins in food products, the developed methods were applied to the analysis of several commercial samples partly produced worldwide. The Fusarium toxins deoxynivalenol and its conjugated metabolite deoxynivalenol-3-glucoside turned out to be the most abundant toxins. None of the other modified mycotoxins were quantified in the samples. However, one cereal sample showed traces of zearalenone- 14-sulfate below the limit of quantification. Moreover, pesticides, plant growth regulators, and tropane alkaloids were investigated in this thesis. Pesticides present biologically highly effective compounds applied in the environment to protect humans from the hazardous effects of pests. While plant growth regulators show similar functions, mainly improving agricultural production, tropane alkaloids are naturally occurring secondary metabolites mainly in the species of Solanaceae that may pose unintended poisoning of humans. The third part of the present thesis aimed to analyze cereal-relevant compounds simultaneously, wherefore a multi-method for the analysis of (modified) mycotoxins, pesticides, plant growth regulators, and tropane alkaloids was established. After processing the samples, this should be done in a single extraction step with subsequent one-time measurements. Various sample preparation procedures were compared, whereby an approach based on an acidified acetonitrile/water extraction, followed by an online clean-up, was finally chosen. The simultaneous determination of more than 350 analytes required an analytical tool that offered an increased resolving power, represented as an enhanced peak capacity, and the possibility of analyzing a broad polarity range. Thus, a two-dimensional LC-MS/MS system based on two different separation mechanisms that performed orthogonal to one another was used for the analysis. Validation of the developed method revealed good performance characteristics for most analytes, while subsequent application showed that 86\% of the samples were contaminated with at least one compound. In summary, this thesis provides novel insights into the analysis of food-relevant (modified) mycotoxins. Different sample preparation and LC-MS/MS approaches were introduced, resulting in the development of three new analytical methods. For the first time, such a high number of modified mycotoxins was included in multi-mycotoxin methods and a multi-method ranging both contaminants and residues. Although first steps towards the analysis of modified mycotoxins have been made, further research is needed to elucidate their (co-) occurrence and toxicological behavior in order to understand their relevance to human health in the future.}, language = {en} } @phdthesis{Winkelbeiner2020, author = {Winkelbeiner, Nicola Lisa}, title = {Impact of element species on DNA repair processes}, pages = {XV, 182, iii}, year = {2020}, language = {en} } @phdthesis{Schiborn2020, author = {Schiborn, Catarina}, title = {Extension of the German Diabetes Risk Score with regard to risk communication and cardiovascular outcomes}, school = {Universit{\"a}t Potsdam}, pages = {218}, year = {2020}, language = {en} } @phdthesis{LenihanGeels2020, author = {Lenihan-Geels, Georgia Ngawai}, title = {The regulation of metabolic flexibility by p53 in skeletal muscle and brown adipose tissue}, school = {Universit{\"a}t Potsdam}, year = {2020}, language = {en} } @phdthesis{Martinez2020, author = {Martinez, Maria Teresa Casta{\~n}o}, title = {Effects of Dietary Methionine and Protein Restriction on the Prevention and Treatment of Type 2 Diabetes}, pages = {100}, year = {2020}, language = {en} } @phdthesis{Seebeck2020, author = {Seebeck, Nicole}, title = {Regulation of the organokines FGF21 and chemerin by diet}, doi = {10.25932/publishup-47114}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-471140}, school = {Universit{\"a}t Potsdam}, pages = {i, 132}, year = {2020}, abstract = {The hepatokine FGF21 and the adipokine chemerin have been implicated as metabolic regulators and mediators of inter-tissue crosstalk. While FGF21 is associated with beneficial metabolic effects and is currently being tested as an emerging therapeutic for obesity and diabetes, chemerin is linked to inflammation-mediated insulin resistance. However, dietary regulation of both organokines and their role in tissue interaction needs further investigation. The LEMBAS nutritional intervention study investigated the effects of two diets differing in their protein content in obese human subjects with non-alcoholic fatty liver disease (NAFLD). The study participants consumed hypocaloric diets containing either low (LP: 10 EN\%, n = 10) or high (HP: 30 EN\%, n = 9) dietary protein 3 weeks prior to bariatric surgery. Before and after the intervention the participants were anthropometrically assessed, blood samples were drawn, and hepatic fat content was determined by MRS. During bariatric surgery, paired subcutaneous and visceral adipose tissue biopsies as well as liver biopsies were collected. The aim of this thesis was to investigate circulating levels and tissue-specific regulation of (1) FGF21 and (2) chemerin in the LEMBAS cohort. The results were compared to data obtained in 92 metabolically healthy subjects with normal glucose tolerance and normal liver fat content. (1) Serum FGF21 concentrations were elevated in the obese subjects, and strongly associated with intrahepatic lipids (IHL). In accordance, FGF21 serum concentrations increased with severity of NAFLD as determined histologically in the liver biopsies. Though both diets were successful in reducing IHL, the effect was more pronounced in the HP group. FGF21 serum concentrations and mRNA expression were bi-directionally regulated by dietary protein, independent from metabolic improvements. In accordance, in the healthy study subjects, serum FGF21 concentrations dropped by more than 60\% in response to the HP diet. A short-term HP intervention confirmed the acute downregulation of FGF21 within 24 hours. Lastly, experiments in HepG2 cell cultures and primary murine hepatocytes identified nitrogen metabolites (NH4Cl and glutamine) to dose-dependently suppress FGF21 expression. (2) Circulating chemerin concentrations were considerably elevated in the obese versus lean study participants and differently associated with markers of obesity and NAFLD in the two cohorts. The adipokine decreased in response to the hypocaloric interventions while an unhealthy high-fat diet induced a rise in chemerin serum levels. In the lean subjects, mRNA expression of RARRES2, encoding chemerin, was strongly and positively correlated with expression of several cytokines, including MCP1, TNFα, and IL6, as well as markers of macrophage infiltration in the subcutaneous fat depot. However, RARRES2 was not associated with any cytokine assessed in the obese subjects and the data indicated an involvement of chemerin not only in the onset but also resolution of inflammation. Analyses of the tissue biopsies and experiments in human primary adipocytes point towards a role of chemerin in adipogenesis while discrepancies between the in vivo and in vitro data were detected. Taken together, the results of this thesis demonstrate that circulating FGF21 and chemerin levels are considerably elevated in obesity and responsive to dietary interventions. FGF21 was acutely and bi-directionally regulated by dietary protein in a hepatocyte-autonomous manner. Given that both, a lack in essential amino acids and excessive nitrogen intake, exert metabolic stress, FGF21 may serve as an endocrine signal for dietary protein balance. Lastly, the data revealed that chemerin is derailed in obesity and associated with obesity-related inflammation. However, future studies on chemerin should consider functional and regulatory differences between secreted and tissue-specific isoforms.}, language = {en} } @phdthesis{Kochlik2019, author = {Kochlik, Bastian Max}, title = {Relevance of biomarkers for the diagnosis of the frailty syndrome}, doi = {10.25932/publishup-44118}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441186}, school = {Universit{\"a}t Potsdam}, pages = {IV, 99}, year = {2019}, abstract = {Frailty and sarcopenia share some underlying characteristics like loss of muscle mass, low muscle strength, and low physical performance. Imaging parameters and functional examinations mainly assess frailty and sarcopenia criteria; however, these measures can have limitations in clinical settings. Therefore, finding suitable biomarkers that reflect a catabolic muscle state e.g. an elevated muscle protein turnover as suggested in frailty, are becoming more relevant concerning frailty diagnosis and risk assessment. 3-Methylhistidine (3-MH) and its ratios 3-MH-to-creatinine (3-MH/Crea) and 3 MH-to-estimated glomerular filtration rate (3-MH/eGFR) are under discussion as possible biomarkers for muscle protein turnover and might support the diagnosis of frailty. However, there is some skepticism about the reliability of 3-MH measures since confounders such as meat and fish intake might influence 3-MH plasma concentrations. Therefore, the influence of dietary habits and an intervention with white meat on plasma 3-MH was determined in young and healthy individuals. In another study, the cross-sectional associations of plasma 3-MH, 3-MH/Crea and 3-MH/eGFR with the frailty status (robust, pre-frail and frail) were investigated. Oxidative stress (OS) is a possible contributor to frailty development, and high OS levels as well as low micronutrient levels are associated with the frailty syndrome. However, data on simultaneous measures of OS biomarkers together with micronutrients are lacking in studies including frail, pre-frail and robust individuals. Therefore, cross-sectional associations of protein carbonyls (PrCarb), 3-nitrotyrosine (3-NT) and several micronutrients with the frailty status were determined. A validated UPLC-MS/MS (ultra-performance liquid chromatography tandem mass spectrometry) method for the simultaneous quantification of 3-MH and 1-MH (1 methylhistidine, as marker for meat and fish consumption) was presented and used for further analyses. Omnivores showed higher plasma 3-MH and 1-MH concentrations than vegetarians and a white meat intervention resulted in an increase in plasma 3-MH, 3 MH/Crea, 1-MH and 1-MH/Crea in omnivores. Elevated 3-MH and 3-MH/Crea levels declined significantly within 24 hours after this white meat intervention. Thus, 3-MH and 3-MH/Crea might be used as biomarker for muscle protein turnover when subjects did not consume meat 24 hours prior to blood samplings. Plasma 3-MH, 3-MH/Crea and 3-MH/eGFR were higher in frail individuals than in robust individuals. Additionally, these biomarkers were positively associated with frailty in linear regression models, and higher odds to be frail were found for every increase in 3 MH and 3-MH/eGFR quintile in multivariable logistic regression models adjusted for several confounders. This was the first study using 3-MH/eGFR and it is concluded that plasma 3-MH, 3-MH/Crea and 3-MH/eGFR might be used to identify frail individuals or individuals at higher risk to be frail, and that there might be threshold concentrations or ratios to support these diagnoses. Higher vitamin D3, lutein/zeaxanthin, γ-tocopherol, α-carotene, β-carotene, lycopene and β-cryptoxanthin concentrations and additionally lower PrCarb concentrations were found in robust compared to frail individuals in multivariate linear models. Frail subjects had higher odds to be in the lowest than in the highest tertile for vitamin D3 α-tocopherol, α-carotene, β-carotene, lycopene, lutein/zeaxanthin, and β cryptoxanthin, and had higher odds to be in the highest than in the lowest tertile for PrCarb than robust individuals in multivariate logistic regression models. Thus, a low micronutrient together with a high PrCarb status is associated with pre-frailty and frailty.}, language = {en} } @phdthesis{Eichelmann2019, author = {Eichelmann, Fabian}, title = {Novel adipokines as inflammatory biomarkers of chronic disease risk}, school = {Universit{\"a}t Potsdam}, pages = {133}, year = {2019}, language = {en} } @phdthesis{Gaballa2019, author = {Gaballa, Mohamed Mahmoud Salem Ahmed}, title = {New pharmacological approaches targeting vascular calcification in chronic kidney disease}, address = {Potsdam}, school = {Universit{\"a}t Potsdam}, pages = {X, 110}, year = {2019}, language = {en} } @phdthesis{Kehm2019, author = {Kehm, Richard}, title = {The impact of metabolic stress and aging on functionality and integrity of pancreatic islets and beta-cells}, doi = {10.25932/publishup-44109}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-441099}, school = {Universit{\"a}t Potsdam}, pages = {VI, 138}, year = {2019}, abstract = {The increasing age of worldwide population is a major contributor for the rising prevalence of major pathologies and disease, such as type 2 diabetes, mediated by massive insulin resistance and a decline in functional beta-cell mass, highly associated with an elevated incidence of obesity. Thus, the impact of aging under physiological conditions and in combination with diet-induced metabolic stress on characteristics of pancreatic islets and beta-cells, with the focus on functionality and structural integrity, were investigated in the present dissertation. Primarily induced by malnutrition due to chronic and excess intake of high caloric diets, containing large amounts of carbohydrates and fats, obesity followed by systemic inflammation and peripheral insulin resistance occurs over time, initiating metabolic stress conditions. Elevated insulin demands initiate an adaptive response by beta-cell mass expansion due to increased proliferation, but prolonged stress conditions drive beta-cell failure and loss. Aging has been also shown to affect beta-cell functionality and morphology, in particular by proliferative limitations. However, most studies in rodents were performed under beta-cell challenging conditions, such as high-fat diet interventions. Thus, in the first part of the thesis (publication I), a characterization of age-related alterations on pancreatic islets and beta-cells was performed by using plasma samples and pancreatic tissue sections of standard diet-fed C57BL/6J wild-type mice in several age groups (2.5, 5, 10, 15 and 21 months). Aging was accompanied by decreased but sustained islet proliferative potential as well as an induction of cellular senescence. This was associated with a progressive islet expansion to maintain normoglycemia throughout lifespan. Moreover, beta-cell function and mass were not impaired although the formation and accumulation of AGEs occurred, located predominantly in the islet vasculature, accompanied by an induction of oxidative and nitrosative (redox) stress. The nutritional behavior throughout human lifespan; however, is not restricted to a balanced diet. This emphasizes the significance to investigate malnutrition by the intake of high-energy diets, inducing metabolic stress conditions that synergistically with aging might amplify the detrimental effects on endocrine pancreas. Using diabetes-prone NZO mice aged 7 weeks, fed a dietary regimen of carbohydrate restriction for different periods (young mice - 11 weeks, middle-aged mice - 32 weeks) followed by a carbohydrate intervention for 3 weeks, offered the opportunity to distinguish the effects of diet-induced metabolic stress in different ages on the functionality and integrity of pancreatic islets and their beta-cells (publication II, manuscript). Interestingly, while young NZO mice exhibited massive hyperglycemia in response to diet-induced metabolic stress accompanied by beta-cell dysfunction and apoptosis, middle-aged animals revealed only moderate hyperglycemia by the maintenance of functional beta-cells. The loss of functional beta-cell mass in islets of young mice was associated with reduced expression of PDX1 transcription factor, increased endocrine AGE formation and related redox stress as well as TXNIP-dependent induction of the mitochondrial death pathway. Although the amounts of secreted insulin and the proliferative potential were comparable in both age groups, islets of middle-aged mice exhibited sustained PDX1 expression, almost regular insulin secretory function, increased capacity for cell cycle progression as well as maintained redox potential. The results of the present thesis indicate a loss of functional beta-cell mass in young diabetes-prone NZO mice, occurring by redox imbalance and induction of apoptotic signaling pathways. In contrast, aging under physiological conditions in C57BL/6J mice and in combination with diet-induced metabolic stress in NZO mice does not appear to have adverse effects on the functionality and structural integrity of pancreatic islets and beta-cells, associated with adaptive responses on changing metabolic demands. However, considering the detrimental effects of aging, it has to be assumed that the compensatory potential of mice might be exhausted at a later point of time, finally leading to a loss of functional beta-cell mass and the onset and progression of type 2 diabetes. The polygenic, diabetes-prone NZO mouse is a suitable model for the investigation of human obesity-associated type 2 diabetes. However, mice at advanced age attenuated the diabetic phenotype or do not respond to the dietary stimuli. This might be explained by the middle age of mice, corresponding to the human age of about 38-40 years, in which the compensatory mechanisms of pancreatic islets and beta cells towards metabolic stress conditions are presumably more active.}, language = {en} } @phdthesis{Radloff2018, author = {Radloff, Katrin}, title = {The role of the fatty acid profile and its modulation by cytokines in the systemic inflammation in cancer cachexia}, school = {Universit{\"a}t Potsdam}, pages = {156}, year = {2018}, abstract = {Systemic inflammation is a hallmark of cancer cachexia. Among tumor-host interactions, the white adipose tissue (WAT) is an important contributor to inflammation as it suffers morphological reorganization and lipolysis, releasing free fatty acids (FA), bioactive lipid mediators (LM) and pro-inflammatory cytokines, which accentuate the activation of pro-inflammatory signaling pathways and the recruitment of immune cells to the tissue. This project aimed to investigate which inflammatory factors are involved in the local adipose tissue inflammation and what is the influence of such factors upon enzymes involved in FA or LM metabolism in healthy individuals (Control), weight stable gastro-intestinal cancer patients (WSC) and cachectic cancer patients (CC). The results demonstrated that the inflammatory signature of systemic inflammation is different from local adipose tissue inflammation. The systemic inflammation of the cachectic cancer patients was characterized by higher levels of circulating saturated fatty acids (SFA), tumor-necrosis-factor-α (TNF-α), interleukins IL-6, IL-8 and CRP while levels of polyunsaturated fatty acids (PUFAs), especially n3-PUFAs, were lower in CC than in the other groups. In vitro and in adipose tissue explants, pro-inflammatory cytokines and SFAs were shown to increase the chemokines IL-8 and CXCL10 that were found to be augmented in adipose tissue inflammation in CC which was more profound in the visceral adipose tissue (VAT) than in subcutaneous adipose tissue (SAT). Systemic inflammation was negatively associated with the expression of PUFA synthesizing enzymes, though gene and protein expression did hardly differ between groups. The effects of inflammatory factors on enzymes in the whole tissue could have been masked by differentiated modulation of the diverse cell types in the same tissue. In vitro experiments showed that the expression of FA-modifying enzymes such as desaturases and elongases in adipocytes and macrophages was regulated into opposing directions by TNF-α, IL-6, LPS or palmitate. The higher plasma concentration of the pro-resolving LM resolvin D1 in CC cannot compensate the overall inflammatory status and the results indicate that inflammatory cytokines interfere with synthesis pathways of pro-resolving LM. In summary, the data revealed a complex inter-tissue and inter-cellular crosstalk mediated by pro-inflammatory cytokines and lipid compounds enhancing inflammation in cancer cachexia by feed-forward mechanisms.}, language = {en} } @phdthesis{Mueller2018, author = {M{\"u}ller, Sandra Marie}, title = {Food-relevant arsenic species}, school = {Universit{\"a}t Potsdam}, pages = {163, Viii}, year = {2018}, language = {en} } @phdthesis{Ring2018, author = {Ring, Christiane}, title = {The role of the commensal gut bacterium Akkermansia muciniphila in acute and chronic intestinal inflammation}, year = {2018}, abstract = {Microbiota analyses of patients suffering from various diseases suggest a beneficial role of Akkermansia muciniphila in the maintenance of health, whereas several studies in animal models of intestinal inflammation report that this organism may aggravate inflammation. Therefore, it is important to clarify under which circumstances A. muciniphila exerts negative effects in the intestine of its host. The previously reported observation that A. muciniphila aggravates acute intestinal inflammation in the Salmonella enterica serovar Typhimurium infection mouse model colonized with a simplified human intestinal microbiota was investigated in this study. To unravel the underlying mechanism that led to the observed phenomenon, the time course of events following the infection was analyzed. In mice colonized with a simplified human intestinal microbiota, Salmonella infection induced clear signs of intestinal inflammation three days post infection. The inflammatory response was similar in mice colonized with A. muciniphila before Salmonella infection. These observations were independent of the time when colonization with the simplified human intestinal microbiota occurred, right after birth or only after weaning, and contradict the previous report. To find out whether A. muciniphila influences the development of chronic intestinal inflammation in a genetically predisposed host, mono-associated interleukin-10-deficient (Il10-/-) mice, Il10-/- mice dual-associated with A. muciniphila and colitogenic Escherichia coli NC101, as well as Il10-/- mice associated with A. muciniphila and a simplified human intestinal microbiota were compared to the respective mice without A. muciniphila. The data clearly show that in these gnotobiotic Il10-/- mice, A. muciniphila neither induces intestinal inflammation itself nor modulates it after induction by a colitogenic bacterium or by a simplified human intestinal microbiota. The experiments lead to the conclusion that the promotion of intestinal inflammation is not an intrinsic feature of this bacterium. The results of this study encourage the proposed use of A. muciniphila for the prevention or treatment of metabolic disorders.}, language = {en} } @phdthesis{Weiss2018, author = {Weiß, Stefanie}, title = {Contribution of bacterially synthesized folate vitamers to folate status and impact on crohn's Disease}, school = {Universit{\"a}t Potsdam}, pages = {148}, year = {2018}, language = {en} } @phdthesis{Hasan2018, author = {Hasan, Ahmed Abdallah Abdalrahman Mohamed}, title = {GLP-1 receptor-independent mechanisms of DPP-4 inhibition on renal disease progression}, school = {Universit{\"a}t Potsdam}, pages = {113}, year = {2018}, language = {en} } @phdthesis{Weitkunat2017, author = {Weitkunat, Karolin}, title = {Dietary fibers and short-chain fatty acids in the development of diet-induced obesity}, school = {Universit{\"a}t Potsdam}, pages = {121}, year = {2017}, language = {en} } @phdthesis{Jank2017, author = {Jank, Anne-Marie}, title = {Effects of senescence on microenvironment-progenitor cell interaction}, school = {Universit{\"a}t Potsdam}, pages = {156}, year = {2017}, language = {en} } @phdthesis{Graja2017, author = {Graja, Antonia}, title = {Aging-related changes of progenitor cell function and microenvironment impair brown adipose tissue regeneration}, school = {Universit{\"a}t Potsdam}, pages = {152}, year = {2017}, language = {en} } @phdthesis{Roediger2017, author = {R{\"o}diger, Maria}, title = {The Impact of the ARFRP1 Action at the Golgi Apparatus on Adipocyte Function}, school = {Universit{\"a}t Potsdam}, pages = {116}, year = {2017}, language = {en} } @phdthesis{Wittenbecher2017, author = {Wittenbecher, Clemens}, title = {Linking whole-grain bread, coffee, and red meat to the risk of type 2 diabetes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-404592}, school = {Universit{\"a}t Potsdam}, pages = {XII, 194, ii}, year = {2017}, abstract = {Background: Consumption of whole-grain, coffee, and red meat were consistently related to the risk of developing type 2 diabetes in prospective cohort studies, but potentially underlying biological mechanisms are not well understood. Metabolomics profiles were shown to be sensitive to these dietary exposures, and at the same time to be informative with respect to the risk of type 2 diabetes. Moreover, graphical network-models were demonstrated to reflect the biological processes underlying high-dimensional metabolomics profiles. Aim: The aim of this study was to infer hypotheses on the biological mechanisms that link consumption of whole-grain bread, coffee, and red meat, respectively, to the risk of developing type 2 diabetes. More specifically, it was aimed to consider network models of amino acid and lipid profiles as potential mediators of these risk-relations. Study population: Analyses were conducted in the prospective EPIC-Potsdam cohort (n = 27,548), applying a nested case-cohort design (n = 2731, including 692 incident diabetes cases). Habitual diet was assessed with validated semiquantitative food-frequency questionnaires. Concentrations of 126 metabolites (acylcarnitines, phosphatidylcholines, sphingomyelins, amino acids) were determined in baseline-serum samples. Incident type 2 diabetes cases were assed and validated in an active follow-up procedure. The median follow-up time was 6.6 years. Analytical design: The methodological approach was conceptually based on counterfactual causal inference theory. Observations on the network-encoded conditional independence structure restricted the space of possible causal explanations of observed metabolomics-data patterns. Given basic directionality assumptions (diet affects metabolism; metabolism affects future diabetes incidence), adjustment for a subset of direct neighbours was sufficient to consistently estimate network-independent direct effects. Further model-specification, however, was limited due to missing directionality information on the links between metabolites. Therefore, a multi-model approach was applied to infer the bounds of possible direct effects. All metabolite-exposure links and metabolite-outcome links, respectively, were classified into one of three categories: direct effect, ambiguous (some models indicated an effect others not), and no-effect. Cross-sectional and longitudinal relations were evaluated in multivariable-adjusted linear regression and Cox proportional hazard regression models, respectively. Models were comprehensively adjusted for age, sex, body mass index, prevalence of hypertension, dietary and lifestyle factors, and medication. Results: Consumption of whole-grain bread was related to lower levels of several lipid metabolites with saturated and monounsaturated fatty acids. Coffee was related to lower aromatic and branched-chain amino acids, and had potential effects on the fatty acid profile within lipid classes. Red meat was linked to lower glycine levels and was related to higher circulating concentrations of branched-chain amino acids. In addition, potential marked effects of red meat consumption on the fatty acid composition within the investigated lipid classes were identified. Moreover, potential beneficial and adverse direct effects of metabolites on type 2 diabetes risk were detected. Aromatic amino acids and lipid metabolites with even-chain saturated (C14-C18) and with specific polyunsaturated fatty acids had adverse effects on type 2 diabetes risk. Glycine, glutamine, and lipid metabolites with monounsaturated fatty acids and with other species of polyunsaturated fatty acids were classified as having direct beneficial effects on type 2 diabetes risk. Potential mediators of the diet-diabetes links were identified by graphically overlaying this information in network models. Mediation analyses revealed that effects on lipid metabolites could potentially explain about one fourth of the whole-grain bread effect on type 2 diabetes risk; and that effects of coffee and red meat consumption on amino acid and lipid profiles could potentially explain about two thirds of the altered type 2 diabetes risk linked to these dietary exposures. Conclusion: An algorithm was developed that is capable to integrate single external variables (continuous exposures, survival time) and high-dimensional metabolomics-data in a joint graphical model. Application to the EPIC-Potsdam cohort study revealed that the observed conditional independence patterns were consistent with the a priori mediation hypothesis: Early effects on lipid and amino acid metabolism had the potential to explain large parts of the link between three of the most widely discussed diabetes-related dietary exposures and the risk of developing type 2 diabetes.}, language = {en} } @phdthesis{Eckel2017, author = {Eckel, Nathalie}, title = {Metabolically healthy obesity and metabolically unhealthy normal weight - identification and associated risks}, school = {Universit{\"a}t Potsdam}, pages = {177}, year = {2017}, language = {en} } @phdthesis{Stadion2017, author = {Stadion, Mandy}, title = {Validation and Characterization of lfi202b and Zfp69, two Novel Disease Genes in Obesity-Associated Insulin Resistance}, school = {Universit{\"a}t Potsdam}, pages = {158}, year = {2017}, language = {en} } @phdthesis{Kasch2017, author = {Kasch, Juliane}, title = {Impact of maternal high-fat consumption on offspring exercise performance, skeletal muscle energy metabolism, and obesity susceptibility}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409703}, school = {Universit{\"a}t Potsdam}, pages = {XII, 95, XXV}, year = {2017}, abstract = {Background: Obesity is thought to be the consequence of an unhealthy nutrition and a lack of physical activity. Although the resulting metabolic alterations such as impaired glucose homeostasis and insulin sensitivity can usually be improved by physical activity, some obese patients fail to enhance skeletal muscle metabolic health with exercise training. Since this might be largely heritable, maternal nutrition during pregnancy and lactation is hypothesized to impair offspring skeletal muscle physiology. Objectives: This PhD thesis aims to investigate the consequences of maternal high-fat diet (mHFD) consumption on offspring skeletal muscle physiology and exercise performance. We could show that maternal high-fat diet during gestation and lactation decreases the offspring's training efficiency and endurance performance by influencing the epigenetic profile of their skeletal muscle and altering the adaptation to an acute exercise bout, which in long-term, increases offspring obesity susceptibility. Experimental setup: To investigate this issue in detail, we conducted several studies with a similar maternal feeding regime. Dams (C57BL/6J) were either fed a low-fat diet (LFD; 10 energy\% from fat) or high-fat diet (HFD; 40 energy\% from fat) during pregnancy and lactation. After weaning, male offspring of both maternal groups were switched to a LFD, on which they remained until sacrifice in week 6, 15 or 25. In one study, LFD feeding was followed by HFD provision from week 15 until week 25 to elucidate the effects on offspring obesity susceptibility. In week 7, all mice were randomly allocated to a sedentary group (without running wheel) or an exercised group (with running wheel for voluntary exercise training). Additionally, treadmill endurance tests were conducted to investigate training performance and efficiency. In order to uncover regulatory mechanisms, each study was combined with a specific analytical setup, such as whole genome microarray analysis, gene and protein expression analysis, DNA methylation analyses, and enzyme activity assays. Results: mHFD offspring displayed a reduced training efficiency and endurance capacity. This was not due to an altered skeletal muscle phenotype with changes in fiber size, number, and type. DNA methylation measurements in 6 week old offspring showed a hypomethylation of the Nr4a1 gene in mHFD offspring leading to an increased gene expression. Since Nr4a1 plays an important role in the regulation of skeletal muscle energy metabolism and early exercise adaptation, this could affect offspring training efficiency and exercise performance in later life. Investigation of the acute response to exercise showed that mHFD offspring displayed a reduced gene expression of vascularization markers (Hif1a, Vegfb, etc) pointing towards a reduced angiogenesis which could possibly contribute to their reduced endurance capacity. Furthermore, an impaired glucose utilization of skeletal muscle during the acute exercise bout by an impaired skeletal muscle glucose handling was evidenced by higher blood glucose levels, lower GLUT4 translocation and diminished Lactate dehydrogenase activity in mHFD offspring immediately after the endurance test. These points towards a disturbed use of glucose as a substrate during endurance exercise. Prolonged HFD feeding during adulthood increases offspring fat mass gain in mHFD offspring compared to offspring from low-fat fed mothers and also reduces their insulin sensitivity pointing towards a higher obesity and diabetes susceptibility despite exercise training. Consequently, mHFD reduces offspring responsiveness to the beneficial effects of voluntary exercise training. Conclusion: The results of this PhD thesis demonstrate that mHFD consumption impairs the offspring's training efficiency and endurance capacity, and reduced the beneficial effects of exercise on the development of diet-induced obesity and insulin resistance in the offspring. This might be due to changes in skeletal muscle epigenetic profile and/or an impaired skeletal muscle angiogenesis and glucose utilization during an acute exercise bout, which could contribute to a disturbed adaptive response to exercise training.}, language = {en} } @phdthesis{Jannasch2017, author = {Jannasch, Franziska}, title = {Methodological aspects of the derivation of dietary patterns and their association with type 2 diabetes}, school = {Universit{\"a}t Potsdam}, pages = {X, 205}, year = {2017}, abstract = {Hintergrund: Die Untersuchung von Ern{\"a}hrungsmustern als komplement{\"a}rer Ansatz zu der Untersuchung einzelner Lebensmittel nimmt stetig zu. Generell k{\"o}nnen drei verschiedene Ans{\"a}tze unterschieden werden um Ern{\"a}hrungsmuster herzuleiten: A priori Indizes, welche das Wissen {\"u}ber gesundheitsf{\"o}rderliche und -sch{\"a}dliche Eigenschaften eines Lebensmittels f{\"u}r einen gewissen Endpunkt nutzen; A posteriori (exploratorische) Ern{\"a}hrungsmuster, welche die populationsspezifischen vorliegenden Daten ohne eine vorangegangene Hypothese nutzen; gemischte Methoden, die das Wissen {\"u}ber bestimmte N{\"a}hrstoffe oder Biomarker, welche in der Krankheitsentstehung eine Rolle spielen, nutzen und mit einer exploratorischen Methode kombinieren um krankheitsrelevante Ern{\"a}hrungsmuster zu generieren. Vorangegangene systematische {\"U}bersichtsarbeiten, welche die Evidenz der Assoziation zwischen Ern{\"a}hrungsmustern und Diabetes mellitus Typ 2 zusammenfassten, waren entweder beschr{\"a}nkt auf eine Mustermethode oder kombinierten die Muster verschiedener Methoden, ohne die Zusammensetzung der Ern{\"a}hrungsmuster zu ber{\"u}cksichtigen. Ziel: Das Ziel dieser Dissertation war eine umfassende Untersuchung der Assoziation von Ern{\"a}hrungsmustern mit Diabetes mellitus Typ 2. Das erste Teilprojekt zielte auf die Erstellung einer systematischen {\"U}bersichtsarbeit von prospektiven Studien ab, unter der Ber{\"u}cksichtigung der verschiedenen Methoden zur Herleitung von Ern{\"a}hrungsmustern in der meta-analytischen Zusammenfassung, was in vorangegangen {\"U}bersichtsarbeiten eine Limitation darstellte. Das zweite Teilprojekt hatte die Untersuchung der Assoziation mit Diabetes mellitus Typ 2 von exploratorischen Ern{\"a}hrungsmustern, welche mit der Hauptkomponentenanalyse in einer multi-zentrischen europ{\"a}ischen Fall-Kohorten Studie hergeleitet wurden, zum Ziel. Des Weiteren wurde der eingeschr{\"a}nkten Anwendbarkeit von exploratorischen Mustern in anderen Studienpopulationen mit Methoden der Replikation dieser Ern{\"a}hrungsmuster begegnet. Methoden: Im ersten Teilprojekt wurde eine systematische Literatursuche in den Datenbanken MEDLINE und Web of Science vorgenommen, sowie ein dreistufiger Screeningprozess. Die identifizierten Studien wurden nach den jeweiligen Methoden zur Erstellung von Ern{\"a}hrungsmustern zusammengefasst und Meta-Analysen nur f{\"u}r diejenigen Ern{\"a}hrungsmuster mit vergleichbarer Zusammensetzung vorgenommen. Im zweiten Teilprojekt wurden l{\"a}nderspezifische Ern{\"a}hrungsmuster mittels Hauptkomponentenanalyse aus 36 standardisierten Lebensmittelgruppen hergeleitet. Die Assoziation mit Diabetes mellitus Typ 2 Risiko wurde mit verschieden adjustierten Cox Regressionsmodellen zur Berechnung von Hazardratenverh{\"a}ltnissen untersucht. Die Ern{\"a}hrungsmuster, welche eine signifikante Assoziation mit dem Diabetesrisiko aufzeigten, wurden anschließend {\"u}ber alle L{\"a}nder in der EPIC-InterAct Studie repliziert: Entweder wurden Summenscores ungewichteter standardisierter Lebensmittelgruppen berechnet (wenn die Korrelation mit dem originalen Ern{\"a}hrungsmuster r ≥ 0.90 war) oder Summenscores der Produkte von standardisierten Scoringkoeffizienten mit standardisierten Lebensmittelgruppen (wenn die Korrelation mit dem originalen Ern{\"a}hrungsmuster r < 0.90). Die resultierenden Scores wurden standardisiert nach der Verteilung der gesamten EPIC-InterAct Subkohorte, dann in jedem Land angewendet und die Assoziation mit Diabetes mellitus Typ 2 anhand der Cox Regressionsmodelle berechnet. Anschließend wurden Meta-Analysen zur Berechnung der gepoolten Sch{\"a}tzer durchgef{\"u}hrt. Ergebnisse: Im ersten Teilprojekt ergab die Literatursuche 48 Artikel, welche 16 Kohorten umfassten. Die Einhaltung der Mediterranen Di{\"a}t (relatives Risiko (RR) f{\"u}r den Vergleich der extremen Quantile: 0,87; 95\%-Konfidenzintervall (KI): 0,82, 0,93), der DASH Di{\"a}t (RR: 0,81; 95\%-KI: 0,72, 0,92) und des Alternative Healthy Eating Index (AHEI) (RR: 0,79; 95\%-KI: 0,69, 0,90) war mit einer signifikanten Reduzierung des Diabetesrisikos assoziiert. Exploratorische Ern{\"a}hrungsmuster, charakterisiert durch rotes und verarbeitetes Fleisch, prozessiertes Getreide, hochfette Milchprodukte, Eier und frittierte Produkte, waren positiv mit dem Diabetesrisiko assoziiert (RR: 1,44; 95\%-KI: 1,27, 1,62), w{\"a}hrend Ern{\"a}hrungs-muster, charakterisiert durch Gem{\"u}se, H{\"u}lsenfr{\"u}chte, Obst, Gefl{\"u}gel und Fisch, invers mit dem Diabetesrisiko assoziiert waren (RR: 0,84; 95\%-KI: 0,77, 0,91). Ern{\"a}hrungsmuster, welche mit reduzierter Rangregression hergeleitet wurden und charakterisiert waren durch eine hohe Aufnahme von prozessiertem Getreide, zuckerges{\"u}ßten Getr{\"a}nken und verarbeitetem Fleisch und einen niedrigen Weinkonsum, waren alle signifikant mit dem Diabetesrisiko assoziiert. Im zweiten Teilprojekt konnten zwei wesentliche Ern{\"a}hrungsmuster in jedem Land mit der Hauptkomponentenanalyse hergeleitet werden. Ein Ern{\"a}hrungsmuster, welches in Frankreich hergeleitet wurde und charakterisiert war durch N{\"u}sse, andere Fr{\"u}chte, verarbeitetes Fleisch, Fisch, Eier, Kuchen und Kekse, Kaffee und andere alkoholische Getr{\"a}nke, war signifikant assoziiert mit einem erniedrigten Diabetesrisiko. Drei andere Ern{\"a}hrungsmuster, hergeleitet in Spanien, Norfolk und Oxford, welche sich erheblich in ihrer Zusammensetzung unterschieden, waren mit einem erh{\"o}hten Diabetesrisiko assoziiert. Keine der Replikationen dieser vier Ern{\"a}hrungsmuster konnte die signifikante Assoziation mit Diabetes mellitus Typ 2 {\"u}ber andere L{\"a}nder best{\"a}tigen. Schlussfolgerung: Aus der systematischen {\"U}bersichtsarbeit ließ sich schlussfolgern, dass Ern{\"a}hrungsweisen gem{\"a}ß der Mediterranen Di{\"a}t, DASH und AHEI ein starkes Potenzial zur Pr{\"a}vention von Diabetes mellitus Typ 2 zu haben, obwohl sie sich in einigen Komponenten unterscheiden. Exploratorische Ern{\"a}hrungsmuster wurden basierend auf konkordanten Lebensmitteln gruppiert und waren signifikant mit dem Diabetesrisiko assoziiert, auch wenn die Untersuchungen einzelner Lebensmittel eher begrenzte Evidenz f{\"u}r einen Zusammenhang aufwiesen. Trotzdem bleiben sie populationsspezifische Beobachtungen. Das wurde auch in dem zweiten Teilprojekt unterstrichen, als l{\"a}nderspezifische Ern{\"a}hrungsmuster generiert wurden und keines der Ern{\"a}hrungsmuster, welches signifikant mit dem Diabetesrisiko assoziiert war, durch Simplifizierung oder Replikation der Musterstruktur des Originalmusters {\"u}ber alle L{\"a}nder best{\"a}tigt werden konnte. F{\"u}r drei RRR-Muster konnten konsistente positive Assoziationen mit dem Diabetesrisiko {\"u}ber verschiedene Studienpopulationen beobachtet werden.}, language = {en} } @phdthesis{Kamitz2016, author = {Kamitz, Anne}, title = {Identification and positional cloning of Ltg/NZO; a novel susceptibility locus associated with fatty liver disease}, school = {Universit{\"a}t Potsdam}, pages = {102}, year = {2016}, language = {en} } @phdthesis{GonzalezCamargo2016, author = {Gonzalez Camargo, Rodolfo}, title = {Insulin resistance in cancer cachexia and metabolic syndrome}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-100973}, school = {Universit{\"a}t Potsdam}, pages = {104}, year = {2016}, abstract = {The ever-increasing fat content in Western diet, combined with decreased levels of physical activity, greatly enhance the incidence of metabolic-related diseases. Cancer cachexia (CC) and Metabolic syndrome (MetS) are both multifactorial highly complex metabolism related syndromes, whose etiology is not fully understood, as the mechanisms underlying their development are not completely unveiled. Nevertheless, despite being considered "opposite sides", MetS and CC share several common issues such as insulin resistance and low-grade inflammation. In these scenarios, tissue macrophages act as key players, due to their capacity to produce and release inflammatory mediators. One of the main features of MetS is hyperinsulinemia, which is generally associated with an attempt of the β-cell to compensate for diminished insulin sensitivity (insulin resistance). There is growing evidence that hyperinsulinemia per se may contribute to the development of insulin resistance, through the establishment of low grade inflammation in insulin responsive tissues, especially in the liver (as insulin is secreted by the pancreas into the portal circulation). The hypothesis of the present study was that insulin may itself provoke an inflammatory response culminating in diminished hepatic insulin sensitivity. To address this premise, firstly, human cell line U937 differentiated macrophages were exposed to insulin, LPS and PGE2. In these cells, insulin significantly augmented the gene expression of the pro-inflammatory mediators IL-1β, IL-8, CCL2, Oncostatin M (OSM) and microsomal prostaglandin E2 synthase (mPGES1), and of the anti-inflammatory mediator IL-10. Moreover, the synergism between insulin and LPS enhanced the induction provoked by LPS in IL-1β, IL-8, IL-6, CCL2 and TNF-α gene. When combined with PGE2, insulin enhanced the induction provoked by PGE2 in IL-1β, mPGES1 and COX2, and attenuated the inhibition induced by PGE2 in CCL2 and TNF-α gene expression contributing to an enhanced inflammatory response by both mechanisms. Supernatants of insulin-treated U937 macrophages reduced the insulin-dependent induction of glucokinase in hepatocytes by 50\%. Cytokines contained in the supernatant of insulin-treated U937 macrophages also activated hepatocytes ERK1/2, resulting in inhibitory serine phosphorylation of the insulin receptor substrate. Additionally, the transcription factor STAT3 was activated by phosphorylation resulting in the induction of SOCS3, which is capable of interrupting the insulin receptor signal chain. MicroRNAs, non-coding RNAs linked to protein expression regulation, nowadays recognized as active players in the generation of several inflammatory disorders such as cancer and type II diabetes are also of interest. Considering that in cancer cachexia, patients are highly affected by insulin resistance and inflammation, control, non-cachectic and cachectic cancer patients were selected and the respective circulating levels of pro-inflammatory mediators and microRNA-21-5p, a posttranscriptional regulator of STAT3 expression, assessed and correlated. Cachectic patients circulating cytokines IL-6 and IL-8 levels were significantly higher than those of non-cachectic and controls, and the expression of microRNA-21-5p was significantly lower. Additionally, microRNA-21-5p reduced expression correlated negatively with IL-6 plasma levels. These results indicate that hyperinsulinemia per se might contribute to the low grade inflammation prevailing in MetS patients and thereby promote the development of insulin resistance particularly in the liver. Diminished MicroRNA-21-5p expression may enhance inflammation and STAT3 expression in cachectic patients, contributing to the development of insulin resistance.}, language = {en} } @phdthesis{Markova2016, author = {Markova, Mariya}, title = {Metabolic and molecular effects of two different isocaloric high protein diets in subjects with type 2 diabetes}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-394310}, school = {Universit{\"a}t Potsdam}, pages = {x, 127}, year = {2016}, abstract = {Ern{\"a}hrung stellt ein wichtiger Faktor in der Pr{\"a}vention und Therapie von Typ-2-Diabetes dar. Fr{\"u}here Studien haben gezeigt, dass Hochproteindi{\"a}ten sowohl positive als auch negative Effekte auf den Metabolismus hervorrufen. Jedoch ist unklar, ob die Herkunft des Proteins dabei eine Rolle spielt. In der LeguAN-Studie wurden die Effekte von zwei unterschiedlichen Hochproteindi{\"a}ten, entweder tierischer oder pflanzlicher Herkunft, bei Typ-2-Diabetes Patienten untersucht. Beide Di{\"a}ten enthielten 30 EN\% Proteine, 40 EN\% Kohlenhydrate und 30 EN\% Fette. Der Anteil an Ballaststoffen, der glyk{\"a}mischer Index und die Fettkomposition waren in beiden Di{\"a}ten {\"a}hnlich. Die Proteinaufnahme war h{\"o}her, w{\"a}hrend die Fettaufnahme niedriger im Vergleich zu den fr{\"u}heren Ern{\"a}hrungsgewohnheiten der Probanden war. Insgesamt f{\"u}hrten beide Di{\"a}tinterventionen zu einer Verbesserung der glyk{\"a}mischen Kontrolle, der Insulinsensitivit{\"a}t, des Leberfettgehalts und kardiovaskul{\"a}rer Risikomarkern ohne wesentliche Unterschiede zwischen den Proteintypen. In beiden Interventionsgruppen wurden die n{\"u}chternen Glukosewerte zusammen mit Indizes von Insulinresistenz in einem unterschiedlichen Ausmaß, jedoch ohne signifikante Unterschiede zwischen beiden Di{\"a}ten verbessert. Die Reduktion von HbA1c war ausgepr{\"a}gter in der pflanzlichen Gruppe, w{\"a}hrend sich die Insulinsensitivit{\"a}t mehr in der tierischen Gruppe erh{\"o}hte. Die Hochproteindi{\"a}ten hatten nur einen geringf{\"u}gigen Einfluss auf den postprandialen Metabolismus. Dies zeigte sich durch eine leichte Verbesserung der Indizes f{\"u}r Insulinsekretion, -sensitivit{\"a}t und -degradation sowie der Werte der freien Fetts{\"a}uren. Mit Ausnahme des Einflusses auf die GIP-Sekretion riefen die tierische und die pflanzliche Testmahlzeit {\"a}hnliche metabolische und hormonelle Antworten, trotz unterschiedlicher Aminos{\"a}urenzusammensetzung. Die tierische Hochproteindi{\"a}t f{\"u}hrte zu einer selektiven Zunahme der fettfreien Masse und Abnahme der Fettmasse, was nicht signifikant unterschiedlich von der pflanzlichen Gruppe war. Dar{\"u}ber hinaus reduzierten die Hochproteindi{\"a}ten den Leberfettgehalt um durchschnittlich 42\%. Die Reduktion des Leberfettgehaltes ging mit einer Verminderung der Lipogenese, der Lipolyse und des freien Fetts{\"a}ure Flux einher. Beide Interventionen induzierten einen moderaten Abfall von Leberenzymen im Blut. Die Reduktion des Leberfetts war mit einer verbesserten Glukosehom{\"o}ostase und Insulinsensitivit{\"a}t assoziiert. Blutlipide sanken in allen Probanden, was eventuell auf die niedrigere Fettaufnahme zur{\"u}ckzuf{\"u}hren war. Weiterhin waren die Spiegel an Harns{\"a}ure und Inflammationsmarkern erniedrigt unabh{\"a}ngig von der Proteinquelle. Die Werte des systolischen und diastolischen Blutdrucks sanken nur in der pflanzlichen Gruppe, was auf eine potentielle Rolle von Arginin hinweist. Es wurden keine Hinweise auf eine beeintr{\"a}chtigte Nierenfunktion durch die 6-w{\"o}chige Hochproteindi{\"a}ten beobachtet unabh{\"a}ngig von der Herkunft der Proteine. Serumkreatinin war nur in der pflanzlichen Gruppe signifikant reduziert, was eventuell an dem geringen Kreatingehalt der pflanzlichen Nahrungsmittel liegen k{\"o}nnte. Jedoch sind l{\"a}ngere Studien n{\"o}tig, um die Sicherheit von Hochproteindi{\"a}ten vollkommen aufkl{\"a}ren zu k{\"o}nnen. Des Weiteren verursachte keine der Di{\"a}ten eine Induktion des mTOR Signalwegs weder im Fettgewebe noch in Blutzellen. Die Verbesserung der Ganzk{\"o}rper-Insulinsensitivit{\"a}t deutete auch auf keine Aktivierung von mTOR und keine Verschlechterung der Insulinsensitivit{\"a}t im Skeletmuskel hin. Ein nennenswerter Befund war die erhebliche Reduktion von FGF21, einem wichtigen Regulator metabolischer Prozesse, um ungef{\"a}hr 50\% bei beiden Proteinarten. Ob hepatischer ER-Stress, Ammoniumniveau oder die Makron{\"a}hrstoffpr{\"a}ferenz hinter dem paradoxen Ergebnis stehen, sollte weiter im Detail untersucht werden. Entgegen der anf{\"a}nglichen Erwartung und der bisherigen Studienlage zeigte die pflanzlich-betonte Hochproteindi{\"a}t keine klaren Vorteile gegen{\"u}ber der tierischen Di{\"a}t. Der ausgepr{\"a}gte g{\"u}nstige Effekt des tierischen Proteins auf Insulinhom{\"o}ostase trotz des hohen BCAA-Gehaltes war sicherlich unerwartet und deutet darauf hin, dass bei dem l{\"a}ngeren Verzehr andere komplexe metabolische Adaptationen stattfinden. Einen weiteren Aspekt stellt der niedrigere Fettverzehr dar, der eventuell auch zu den Verbesserungen in beiden Gruppen beigetragen hat. Zusammenfassend l{\"a}sst sich sagen, dass eine 6-w{\"o}chige Di{\"a}t mit 30 EN\% Proteinen (entweder pflanzlich oder tierisch), 40 EN\% Kohlenhydraten und 30 EN\% Fetten mit weniger ges{\"a}ttigten Fetten zu metabolischen Verbesserungen bei Typ-2-Diabetes Patienten unabh{\"a}ngig von Proteinherkunft f{\"u}hrt.}, language = {en} } @phdthesis{Ambrosi2016, author = {Ambrosi, Thomas H.}, title = {The Role of Bone-residing Adipocyte Progenitors in Age-related Stem Cell Dysfunction and Regenerative Processes}, school = {Universit{\"a}t Potsdam}, pages = {132}, year = {2016}, language = {en} } @phdthesis{Hallahan2016, author = {Hallahan, Nicole}, title = {Identification and characterization of a T2D QTL arising from an NZO.DBA mouse cross}, school = {Universit{\"a}t Potsdam}, pages = {133}, year = {2016}, language = {en} } @phdthesis{Jaeger2016, author = {J{\"a}ger, Susanne}, title = {Genetic variants and metabolic pathways of type 2 diabetes within the EPIC-Potsdam study}, school = {Universit{\"a}t Potsdam}, pages = {139, XXVII}, year = {2016}, language = {en} } @phdthesis{Reinke2016, author = {Reinke, Julia}, title = {The Role of Kallistatin in Energy Metabolism and Glucose Homeostasis in Mice}, school = {Universit{\"a}t Potsdam}, pages = {77}, year = {2016}, language = {en} } @phdthesis{Reeg2016, author = {Reeg, Sandra}, title = {Degradation of oxidized proteins by the proteasome - Involvement of chaperones and the ubiquitin-system}, school = {Universit{\"a}t Potsdam}, pages = {117}, year = {2016}, language = {en} } @phdthesis{EmantokoDwiPutra2016, author = {Emantoko Dwi Putra, Sulistyo}, title = {Placental DNA Methylation in Association with Maternal Heath and Birth Outcomes}, school = {Universit{\"a}t Potsdam}, year = {2016}, language = {en} } @phdthesis{Errard2016, author = {Errard, Audrey}, title = {Multiple-pest infestations: impact on tomato Solanum lycopersicum biochemistry in the presence/absence of predator, and on pest biology}, school = {Universit{\"a}t Potsdam}, pages = {83}, year = {2016}, language = {en} } @phdthesis{Meyer2015, author = {Meyer, S{\"o}ren}, title = {Toxicity and toxicokinetics of arsenolipids and their metabolites}, school = {Universit{\"a}t Potsdam}, pages = {152, VIII}, year = {2015}, language = {en} } @phdthesis{Prandi2015, author = {Prandi, Simone}, title = {Characterization of the expression and function of bitter taste receptor genes in gastrointestinal tissues}, school = {Universit{\"a}t Potsdam}, pages = {165}, year = {2015}, language = {en} } @phdthesis{Jacobs2015, author = {Jacobs, Simone}, title = {Biological mechanisms of the association between proportions of fatty acids in erythrocyte membranes and type 2 diabetes risk in the EPIC-Potsdam-Study}, pages = {157}, year = {2015}, language = {en} } @phdthesis{Brachs2015, author = {Brachs, Maria}, title = {Genome wide expression analysis and metabolic mechanisms predicting body weight maintenance}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-100767}, school = {Universit{\"a}t Potsdam}, pages = {106}, year = {2015}, abstract = {Obesity is a major health problem for many developing and industrial countries. Increasing rates reach almost 50 \% of the population in some countries and related metabolic diseases including cardiovascular events and T2DM are challenging the health systems. Adiposity, an increase in body fat mass, is a major hallmark of obesity. Adipose tissue is long known not only to store lipids but also to influence whole-body metabolism including food intake, energy expenditure and insulin sensitivity. Adipocytes can store lipids and thereby protect other tissue from lipotoxic damage. However, if the energy intake is higher than the energy expenditure over a sustained time period, adipose tissue will expand. This can lead to an impaired adipose tissue function resulting in higher levels of plasma lipids, which can affect other tissue like skeletal muscle, finally leading to metabolic complications. Several studies showed beneficial metabolic effects of weight reduction in obese subjects immediately after weight loss. However, weight regain is frequently observed along with potential negative effects on cardiovascular risk factors and a high intra-individual response. We performed a body weight maintenance study investigating the mechanisms of weight maintenance after intended WR. Therefore we used a low caloric diet followed by a 12-month life-style intervention. Comprehensive phenotyping including fat and muscle biopsies was conducted to investigate hormonal as well as metabolic influences on body weight regulation. In this study, we showed that weight reduction has numerous potentially beneficial effects on metabolic parameters. After 3-month WR subjects showed significant weight and fat mass reduction, lower TG levels as well as higher insulin sensitivity. Using RNA-Seq to analyse whole fat and muscle transcriptome a strong impact of weight reduction on adipose tissue gene expression was observed. Gene expression alterations over weight reduction included several cellular metabolic genes involved in lipid and glucose metabolism as well as insulin signalling and regulatory pathways. These changes were also associated with anthropometric parameters assigning body composition. Our data indicated that weight reduction leads to a decreased expression of several lipid catabolic as well as anabolic genes. Long-term body weight maintenance might be influenced by several parameters including hormones, metabolic intermediates as well as the transcriptional landscape of metabolic active tissues. Our data showed that genes involved in biosynthesis of unsaturated fatty acids might influence the BMI 18-month after a weight reduction phase. This was further supported by analysing metabolic parameters including RQ and FFA levels. We could show that subjects maintaining their lost body weight had a higher RQ and lower FFA levels, indicating increased metabolic flexibility in subjects. Using this transcriptomic approach we hypothesize that low expression levels of lipid synthetic genes in adipose tissue together with a higher mitochondrial activity in skeletal muscle tissue might be beneficial in terms of body weight maintenance.}, language = {en} } @phdthesis{Baumeier2015, author = {Baumeier, Christian}, title = {Dietary and Pharmacological Strategies for the Prevention and Treatment of Type 2 Diabetes in a Diabetes-Susceptible Mouse Model}, school = {Universit{\"a}t Potsdam}, pages = {148}, year = {2015}, language = {en} } @phdthesis{Bendadani2015, author = {Bendadani, Carolin}, title = {1-Methylpyren: Biotransformation und Gentoxizit{\"a}t}, school = {Universit{\"a}t Potsdam}, pages = {188}, year = {2015}, language = {en} } @phdthesis{Sarem2015, author = {Sarem, Zeinab}, title = {Regulation of IGF-1 bioactivity by dietary hormones, impact of glucagon and insulin-induced hypoglycemia}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-82198}, school = {Universit{\"a}t Potsdam}, pages = {IX, 64, IV, XIII}, year = {2015}, abstract = {Der Zusammenhang zwischen Ern{\"a}hrung und der Entwicklung von chronischen Krankenheiten wie metabolischem Syndrom, Diabetes mellitus, Krebs und kardiovaskul{\"a}ren Erkrankungen wurde untersucht. Ver{\"a}nderungen der GH-IGF-1 Achse in Verbindung mit ern{\"a}hrungsbedingten Erkrankungen wurden fr{\"u}her beschrieben. Das Wechselspiel zwischen GH, gesamt IGF-1 und verschiedenen hemmenden und stimulierenden IGF-1 bindenden Proteinen (IGFBPs) bestimmt die IGF-1 Bioaktivit{\"a}t, die als die F{\"a}higkeit von IGF-1 die Phosphorylierung von seinem Rezeptor und folglich seinem Signalsweg zu induzieren, identifiziert ist. Deshalb reicht die Messung der IGF-1 Bioaktivit{\"a}t aus, um {\"A}nderungen des GH-IGF-1 Systems darzustellen. Studien deuten darauf hin, dass proteinreiche Di{\"a}t, gekennzeichnet durch erh{\"o}hte Glukagonsekretion, und Insulin-induzierte Hypoglyk{\"a}mie die Sterblichkeit erh{\"o}hen, und die Mechanismen sind unklar. Sowohl Glukagon als auch Insulin-induzierte Hypoglyk{\"a}mie stimulieren die GH Sekretion. Das Ziel der vorliegenden Studie war, die Wirkung von Glucagon und Insulin-induzierter Hypoglyk{\"a}mie auf die IGF-1 -Bioaktivit{\"a}t als m{\"o}gliche Mechanismen zu characterizieren. In einer doppelblinden, Placebo-kontrollierten Studie wurde Glukagon intramuskul{\"a}r 13 Patienten mit T1DM (6 M{\"a}nner / 7 Frauen; [ BMI ] : 24,8 ± 0,95 kg / m2) , 11 {\"u}bergewichtigen Teilnehmern (OP ; 5/6 ; 34,4 ± 1,7 kg / m2) und 13 gesunden schlanken Teilnehmern (LP ; 6/7 ; 21,7 ± 0,6 kg / m2) administriert. Zw{\"o}lf {\"u}bergewichtige Teilnehmer (OP ; 6/6 ; 34,4 ± 1,7 kg / m2) und 13 gesunde schlanke Teilnehmer (LP ; 6/7 ; 21,7 ± 0,6 kg / m2) f{\"u}hrten Insulintoleranztests in einer weiteren doppelblinden, Plazebo- kontrollierten Studie durch. {\"A}nderungen des GH, gesamt-IGF-1, der IGF-bindenden Proteinen ( IGFBPs ) und der IGF-1-Bioaktivit{\"a}t wurden durch das zellbasierte KIRA-Verfahren gemessen. Außerdem wurde die Wechselwirkung zwischen den metabolischen Hormonen (Glucagon und Insulin) und GH-IGF-1-System auf der Transkriptionsebene mit prim{\"a}ren Maus-Hepatozyten untersucht. In dieser Arbeit verringerte Glukagon die IGF-1-Bioaktivit{\"a}t bei den Menschen unabh{\"a}ngig von k{\"o}rpereigenen Insulinspiegeln, h{\"o}chstwahrscheinlich durch Modulation des IGFBP-1 und -2. Die Glukagon-induzierte Reduktion der IGF-1-Bioaktivit{\"a}t stellt einen neuen Mechanismus der Wirkung von Glucagon auf die GH-Sekretion dar und kann als m{\"o}gliche Erkl{\"a}rung f{\"u}r die negativen Auswirkungen der proteinreichen Di{\"a}t im Zusammenhang auf das erh{\"o}hte kardiovaskul{\"a}re Risiko und die Mortalit{\"a}t vorgeschlagen werden. Zus{\"a}tzlich wurde die Insulin-induzierten Hypoglyk{\"a}mie eine Abnahme der IGF-1-Bioaktivit{\"a}t durch Hochregulierung von IGFBP-2 zugeordnet. Diese Ergebnisse k{\"o}nnen auf m{\"o}gliche und wenig erforschte Mechanismen zur Erl{\"a}uterung der starken Assoziation zwischen Hypoglyk{\"a}mie und erh{\"o}hter kardiovaskul{\"a}rer Mortalit{\"a}t bei diabetischen Patienten beziehen.}, language = {en} } @phdthesis{Lohren2015, author = {Lohren, Hanna}, title = {Mechanisms of mercury species-mediated neurotoxicity}, school = {Universit{\"a}t Potsdam}, pages = {141, viii}, year = {2015}, language = {en} } @phdthesis{Schiess2015, author = {Schiess, Sonja}, title = {Effects of glucotropaeolin and its breakdown product benzyl isothiocyanate on metabolic, endocrine, and inflammatory parameters in humans}, school = {Universit{\"a}t Potsdam}, pages = {115}, year = {2015}, language = {en} } @phdthesis{Vossenkuhl2015, author = {Vossenkuhl, Birgit}, title = {Transmission of MRSA along the meat supply chain}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-85918}, school = {Universit{\"a}t Potsdam}, pages = {141}, year = {2015}, abstract = {Methicillin-resistente Staphylococcus aureus (MRSA) z{\"a}hlen zu den bedeutendsten antibiotikaresistenten Pathogenen, die vor allem in Krankenh{\"a}usern aber auch außerhalb von Einrichtungen des Gesundheitswesens weit verbreitet sind. Seit einigen Jahren ist eine neue Generation von MRSA auf dem Vormarsch, die vor allem Nutztierbest{\"a}nde als neue Nische besiedelt. Diese sogenannten Nutztier-assoziierten MRSA wurden wiederholt bei wirtschaftlich bedeutenden Nutztieren sowie daraus gewonnenem Fleisch nachgewiesen. Im Rahmen der vorliegenden Arbeit wurde ein methodischer Ansatz verfolgt, um die Hypothese einer m{\"o}glichen {\"U}bertragung von Nutztier-assoziierten MRSA entlang der Lebensmittelkette vom Tier auf dessen Fleisch zu best{\"a}tigen. Angepasst an die Unterschiede in den verf{\"u}gbaren Daten wurden daf{\"u}r zwei neue Konzepte erstellt. Zur Analyse der {\"U}bertragung von MRSA entlang der Schlachtkette wurde ein mathematisches Modell des Schweineschlachtprozesses entwickelt, welches dazu geeignet ist, den Verlauf der MRSA-Pr{\"a}valenz entlang der Schlachtkette zu quantifizieren sowie kritische Prozessschritte f{\"u}r eine MRSA-{\"U}bertragung zu identifizieren. Anhand von Pr{\"a}valenzdaten ist es dem Modell m{\"o}glich, die durchschnittlichen MRSA-Eliminations- und Kontaminationsraten jedes einzelnen Prozessschrittes zu sch{\"a}tzen, die anschließend in eine Monte-Carlo-Simulation einfließen. Im Ergebnis konnte gezeigt werden, dass es generell m{\"o}glich ist, die MRSA Pr{\"a}valenz im Laufe des Schlachtprozesses auf ein niedriges finales Niveau zwischen 0,15 bis 1,15\% zu reduzieren. Vor allem das Br{\"u}hen und Abfl{\"a}mmen der Schlachtk{\"o}rper wurden als kritische Prozesse im Hinblick auf eine MRSA-Dekontamination identifiziert. In Deutschland werden regelm{\"a}ßig MRSA-Pr{\"a}valenz und Typisierungsdaten auf allen Stufen der Lebensmittelkette verschiedener Nutztiere erfasst. Um die MRSA-Daten dieser Querschnittstudie hinsichtlich einer m{\"o}glichen {\"U}bertragung entlang der Kette zu analysieren, wurde ein neuer statistischer Ansatz entwickelt. Hierf{\"u}r wurde eine Chi-Quadrat-Statistik mit der Berechnung des Czekanowski-{\"A}hnlichkeitsindex kombiniert, um Unterschiede in der Verteilung stammspezifischer Eigenschaften zwischen MRSA aus dem Stall, von Karkassen nach der Schlachtung und aus Fleisch im Einzelhandel zu quantifizieren. Die Methode wurde am Beispiel der Putenfleischkette implementiert und zudem bei der Analyse der Kalbfleischkette angewendet. Die durchgehend hohen {\"A}hnlichkeitswerte zwischen den einzelnen Proben weisen auf eine m{\"o}gliche {\"U}bertragung von MRSA entlang der Lebensmittelkette hin. Die erarbeiteten Methoden sind nicht spezifisch bez{\"u}glich Prozessketten und Pathogenen. Sie bieten somit einen großen Anwendungsbereich und erweitern das Methodenspektrum zur Bewertung bakterieller {\"U}bertragungswege.}, language = {en} } @phdthesis{GuzmanPerez2014, author = {Guzman-Perez, Valentina}, title = {Effect of benzylglucosinolate on signaling pathways associated with type 2 diabetes prevention}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-72351}, school = {Universit{\"a}t Potsdam}, year = {2014}, abstract = {Type 2 diabetes (T2D) is a health problem throughout the world. In 2010, there were nearly 230 million individuals with diabetes worldwide and it is estimated that in the economically advanced countries the cases will increase about 50\% in the next twenty years. Insulin resistance is one of major features in T2D, which is also a risk factor for metabolic and cardiovascular complications. Epidemiological and animal studies have shown that the consumption of vegetables and fruits can delay or prevent the development of the disease, although the underlying mechanisms of these effects are still unclear. Brassica species such as broccoli (Brassica oleracea var. italica) and nasturtium (Tropaeolum majus) possess high content of bioactive phytochemicals, e.g. nitrogen sulfur compounds (glucosinolates and isothiocyanates) and polyphenols largely associated with the prevention of cancer. Isothiocyanates (ITCs) display their anti-carcinogenic potential by inducing detoxicating phase II enzymes and increasing glutathione (GSH) levels in tissues. In T2D diabetes an increase in gluconeogenesis and triglyceride synthesis, and a reduction in fatty acid oxidation accompanied by the presence of reactive oxygen species (ROS) are observed; altogether is the result of an inappropriate response to insulin. Forkhead box O (FOXO) transcription factors play a crucial role in the regulation of insulin effects on gene expression and metabolism, and alterations in FOXO function could contribute to metabolic disorders in diabetes. In this study using stably transfected human osteosarcoma cells (U-2 OS) with constitutive expression of FOXO1 protein labeled with GFP (green fluorescent protein) and human hepatoma cells HepG2 cell cultures, the ability of benzylisothiocyanate (BITC) deriving from benzylglucosinolate, extracted from nasturtium to modulate, i) the insulin-signaling pathway, ii) the intracellular localization of FOXO1 and iii) the expression of proteins involved in glucose metabolism, ROS detoxification, cell cycle arrest and DNA repair was evaluated. BITC promoted oxidative stress and in response to that induced FOXO1 translocation from cytoplasm into the nucleus antagonizing the insulin effect. BITC stimulus was able to down-regulate gluconeogenic enzymes, which can be considered as an anti-diabetic effect; to promote antioxidant resistance expressed by the up-regulation in manganese superoxide dismutase (MnSOD) and detoxification enzymes; to modulate autophagy by induction of BECLIN1 and down-regulation of the mammalian target of rapamycin complex 1 (mTORC1) pathway; and to promote cell cycle arrest and DNA damage repair by up-regulation of the cyclin-dependent kinase inhibitor (p21CIP) and Growth Arrest / DNA Damage Repair (GADD45). Except for the nuclear factor (erythroid derived)-like2 (NRF2) and its influence in the detoxification enzymes gene expression, all the observed effects were independent from FOXO1, protein kinase B (AKT/PKB) and NAD-dependent deacetylase sirtuin-1 (SIRT1). The current study provides evidence that besides of the anticarcinogenic potential, isothiocyanates might have a role in T2D prevention. BITC stimulus mimics the fasting state, in which insulin signaling is not triggered and FOXO proteins remain in the nucleus modulating gene expression of their target genes, with the advantage of a down-regulation of gluconeogenesis instead of its increase. These effects suggest that BITC might be considered as a promising substance in the prevention or treatment of T2D, therefore the factors behind of its modulatory effects need further investigation.}, language = {en} } @phdthesis{Benz2014, author = {Benz, Verena}, title = {Sex-specific differences in the regulation of body weight dynamics and adipose tissue metabolism}, address = {Potsdam}, pages = {119 S.}, year = {2014}, language = {en} } @phdthesis{Schmiedchen2014, author = {Schmiedchen, Bettina}, title = {Vitamin D and its linkage between chronic kidney disease and cardiovascular integrity}, pages = {113}, year = {2014}, language = {en} } @phdthesis{Lang2014, author = {Lang, Iris Scarlett}, title = {Fetal programming of growth and metabolism by maternal dietary composition}, pages = {99}, year = {2014}, language = {en} } @phdthesis{Rothe2013, author = {Rothe, Monique}, title = {Response of intestinal Escherichia coli to dietary factors in the mouse intestine}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-66387}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Diet is a major force influencing the intestinal microbiota. This is obvious from drastic changes in microbiota composition after a dietary alteration. Due to the complexity of the commensal microbiota and the high inter-individual variability, little is known about the bacterial response at the cellular level. The objective of this work was to identify mechanisms that enable gut bacteria to adapt to dietary factors. For this purpose, germ-free mice monoassociated with the commensal Escherichia coli K-12 strain MG1655 were fed three different diets over three weeks: a diet rich in starch, a diet rich in non-digestible lactose and a diet rich in casein. Two dimensional gel electrophoresis and electrospray tandem mass spectrometry were applied to identify differentially expressed proteins of E. coli recovered from small intestine and caecum of mice fed the lactose or casein diets in comparison with those of mice fed the starch diet. Selected differentially expressed bacterial proteins were characterised in vitro for their possible roles in bacterial adaptation to the various diets. Proteins belonging to the oxidative stress regulon oxyR such as alkyl hydroperoxide reductase subunit F (AhpF), DNA protection during starvation protein (Dps) and ferric uptake regulatory protein (Fur), which are required for E. coli's oxidative stress response, were upregulated in E. coli of mice fed the lactose-rich diet. Reporter gene analysis revealed that not only oxidative stress but also carbohydrate-induced osmotic stress led to the OxyR-dependent expression of ahpCF and dps. Moreover, the growth of E. coli mutants lacking the ahpCF or oxyR genes was impaired in the presence of non-digestible sucrose. This indicates that some OxyR-dependent proteins are crucial for the adaptation of E. coli to osmotic stress conditions. In addition, the function of two so far poorly characterised E. coli proteins was analysed: 2 deoxy-D gluconate 3 dehydrogenase (KduD) was upregulated in intestinal E. coli of mice fed the lactose-rich diet and this enzyme and 5 keto 4 deoxyuronate isomerase (KduI) were downregulated on the casein-rich diet. Reporter gene analysis identified galacturonate and glucuronate as inducers of the kduD and kduI gene expression. Moreover, KduI was shown to facilitate the breakdown of these hexuronates, which are normally degraded by uronate isomerase (UxaC), altronate oxidoreductase (UxaB), altronate dehydratase (UxaA), mannonate oxidoreductase (UxuB) and mannonate dehydratase (UxuA), whose expression was repressed by osmotic stress. The growth of kduID-deficient E. coli on galacturonate or glucuronate was impaired in the presence of osmotic stress, suggesting KduI and KduD to compensate for the function of the regular hexuronate degrading enzymes under such conditions. This indicates a novel function of KduI and KduD in E. coli's hexuronate metabolism. Promotion of the intracellular formation of hexuronates by lactose connects these in vitro observations with the induction of KduD on the lactose-rich diet. Taken together, this study demonstrates the crucial influence of osmotic stress on the gene expression of E. coli enzymes involved in stress response and metabolic processes. Therefore, the adaptation to diet-induced osmotic stress is a possible key factor for bacterial colonisation of the intestinal environment.}, language = {en} } @phdthesis{MostafaKamelAbdelfatah2013, author = {Mostafa Kamel Abdelfatah, Ali}, title = {Interactions of food proteins with plant phenolics - modulation of structural, techno- and bio-functional properties of proteins}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69033}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {The phenolic compounds as food components represent the largest group of secondary metabolites in plant foods. The phenolic compounds, e.g. chlorogenic acid (CQA), are susceptible to oxidation by enzymes specially, polyphenol oxidase (PPO) and at alkaline conditions. Both enzymatic and non-enzymatic oxidations occur in the presence of oxygen and produce quinone, which normally further react with other quinone to produce colored compounds (dimers), as well as is capable of undergoing a nucleophilic addition to proteins. The interactions of proteins with the phenolic compounds have received considerable attention in the recent years where, plant phenolic compounds have drawn increasing attention due to their antioxidant properties and their noticeable effects in the prevention of various oxidative stress associated diseases. Green coffee beans are one of the richest sources of chlorogenic acids. Therefore, a green coffee extract would provide an eligible food relevant source for phenolic compounds for modification of proteins. The interaction between 5-CQA and amino acid lysine showed decrease in both free CQA and amino acid groups and only a slight effect on the antioxidative capacity depending on the reaction time was found. Furthermore, this interaction showed a large number of intermediary substances of low intensities. The reaction of lysine with 5-CQA in a model system initially leads to formation of 3-CQA and 4-CQA (both are isomers of 5-CQA), oxidation giving rise to the formation of a dimer which subsequently forms an adduct with lysine to finally result in a benzacridine derivative as reported and confirmed with the aid of HPLC coupled with ESI-MSn. The benzacridine derivative containing a trihydroxy structural element, was found to be yellow, being very reactive with oxygen yielding semiquinone and quinone type of products with characteristic green colors. Finally, the optimal conditions for this interaction as assessed by both the loss of CQA and free amino groups of lysine can be given at pH 7 and 25°C, the interaction increasing with incubation time and depending also on the amount of tyrosinase present. Green coffee bean has a higher diversity and content of phenolics, where besides the CQA isomers and their esters, other conjugates like feruloylquinic acids were also identified, thus documenting differences in phenolic profiles for the two coffee types (Coffea arabica and Coffea robusta). Coffee proteins are modified by interactions with phenolic compounds during the extraction, where those from C. arabica are more susceptible to these interactions compared to C. robusta, and the polyphenol oxidase activity seems to be a crucial factor for the formation of these addition products. Moreover, In-gel digestion combined with MALDI-TOF-MS revealed that the most reactive and susceptible protein fractions to covalent reactions are the α-chains of the 11S storage protein. Thus, based on these results and those supplied by other research groups, a tentative list of possible adduct structures was derived. The diversity of the different CQA derivatives present in green coffee beans complicates the series of reactions occurring, providing a broad palette of reaction products. These interactions influence the properties of protein, where they exposed changes in the solubility and hydrophobicity of proteins compared to faba bean proteins (as control). Modification of milk whey protein products (primarily b-lactoglobulin) with coffee specific phenolics and commercial CQA under enzymatic and alkaline conditions seems to be affecting their chemical, structural and functional properties, where both modifications led to reduced free amino-,thiol groups and tryptophan content. We propose that the disulfide-thiol exchange in the C-terminus of b-lactoglobulin may be initiated by the redox conditions provided in the presence of CQA. The protein structure b-lactoglobulin thereupon becomes more disordered as simulated by molecular dynamic calculation. This unfolding process may additionally be supported by the reaction of the CQA at the proposed sites of modification of -amino groups of lysine (K77, K91, K138, K47) and the thiol group of cysteine (C121). These covalent modifications also decreased the solubility and hydrophobicity of b-lactoglobulin, moreover they provide modified protein samples with a high antioxidative power, thermally more stable as reflected by a higher Td, require less amount of energy to unfold and when emulsified with lutein esters, exhibit their higher stability against UV light. The MALDI-TOF and SDS-PAGE results revealed that proteins treated at alkaline conditions were more strongly modified than those treated under enzymatic conditions. Finally, the results showed a slight change in emulsifying properties of modified proteins.}, language = {en} } @phdthesis{Ganesh2013, author = {Ganesh, Bhanu Priya}, title = {Host-microbe interactions in the inflamed gut}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-69558}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Initiation and perpetuation of inflammatory bowel diseases (IBD) may result from an exaggerated mucosal immune response to the luminal microbiota in a susceptible host. We proposed that this may be caused either 1) by an abnormal microbial composition or 2) by weakening of the protective mucus layer due to excessive mucus degradation, which may lead to an easy access of luminal antigens to the host mucosa triggering inflammation. We tested whether the probiotic Enterococcus faecium NCIMB 10415 (NCIMB) is capable of reducing chronic gut inflammation by changing the existing gut microbiota composition and aimed to identify mechanisms that are involved in possible beneficial effects of the probiotic. To identify health-promoting mechanisms of the strain, we used interleukin (IL)-10 deficient mice that spontaneously develop gut inflammation and fed these mice a diet containing NCIMB (106 cells g-1) for 3, 8 and 24 weeks, respectively. Control mice were fed an identically composed diet but without the probiotic strain. No clear-cut differences between the animals were observed in pro-inflammatory cytokine gene expression and in intestinal microbiota composition after probiotic supplementation. However, we observed a low abundance of the mucin-degrading bacterium Akkermansia muciniphila in the mice that were fed NCIMB for 8 weeks. These low cell numbers were associated with significantly lower interferon gamma (IFN-γ) and IFN-γ-inducible protein (IP-10) mRNA levels as compared to the NCIMB-treated mice that were killed after 3 and 24 weeks of intervention. In conclusion, NCIMB was not capable of reducing gut inflammation in the IL-10-/- mouse model. To further identify the exact role of A. muciniphila and uncover a possible interaction between this bacterium, NCIMB and the host in relation to inflammation, we performed in vitro studies using HT-29 colon cancer cells. The HT-29 cells were treated with bacterial conditioned media obtained by growing either A. muciniphila (AM-CM) or NCIMB (NCIMB-CM) or both together (COMB-CM) in Dulbecco's Modified Eagle Medium (DMEM) for 2 h at 37 °C followed by bacterial cell removal. HT-29 cells treated with COMB-CM displayed reduced cell viability after 18 h (p<0.01) and no viable cells were detected after 24 h of treatment, in contrast to the other groups or heated COMB-CM. Detection of activated caspase-3 in COMB-CM treated groups indicated that death of the HT-29 cells was brought about by apoptosis. It was concluded that either NCIMB or A. muciniphila produce a soluble and heat-sensitive factor during their concomitant presence that influences cell viability in an in vitro system. We currently hypothesize that this factor is a protein, which has not yet been identified. Based on the potential effect of A. muciniphila on inflammation (in vivo) and cell-viability (in vitro) in the presence of NCIMB, we investigated how the presence of A. muciniphila affects the severity of an intestinal Salmonella enterica Typhimurium (STm)-induced gut inflammation using gnotobiotic C3H mice with a background microbiota of eight bacterial species (SIHUMI, referred to as simplified human intestinal microbiota). Presence of A. muciniphila in STm-infected SIHUMI (SIHUMI-AS) mice caused significantly increased histopathology scores and elevated mRNA levels of IFN-γ, IP-10, tumor necrosis factor alpha (TNF-α), IL-12, IL-17 and IL-6 in cecal and colonic tissue. The number of mucin filled goblet cells was 2- to 3- fold lower in cecal tissue of SIHUMI-AS mice compared to SIHUMI mice associated with STm (SIHUMI-S) or A. muciniphila (SIHUMI-A) or SIHUMI mice. Reduced goblet cell numbers significantly correlated with increased IFN-γ (r2 = -0.86, ***P<0.001) in all infected mice. In addition, loss of cecal mucin sulphation was observed in SIHUMI-AS mice. Concomitant presence of A. muciniphila and STm resulted in a drastic change in microbiota composition of the SIHUMI consortium. The proportion of Bacteroides thetaiotaomicron in SIHUMI, SIHUMI-A and SIHUMI-S mice made up to 80-90\% but was completely taken over by STm in SIHUMI-AS mice contributing 94\% to total bacteria. These results suggest that A. muciniphila exacerbates STm-induced intestinal inflammation by its ability to disturb host mucus homeostasis. In conclusion, abnormal microbiota composition together with excessive mucus degradation contributes to severe intestinal inflammation in a susceptible host.}, language = {en} } @phdthesis{Mabrok2013, author = {Mabrok, Hoda Hussein Bakr}, title = {Protective role of lignan-converting bacteria on chemically-induced breast cancer in gnotobiotic rats}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-64933}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Enterolignans (enterodiol and enterolactone) exhibit structural similarity to estradiol and have therefore been hypothesized to modulate hormone related cancers such as breast cancer. The bioactivation of the plant lignan secoisolariciresinol diglucoside (SDG) requires the transformation by intestinal bacteria including the deglycosylation of SDG to secoisolariciresinol (SECO) followed by demethylation and dehydroxylation of SECO to enterodiol (ED). Finally, ED is dehydrogenated to enterolactone (EL). It is unclear whether the bacterial activation of SDG to ED and EL is crucial for the cancer preventing effects of dietary lignans. The possible protective effect of bacterial lignan transformation on a 7,12 dimethylbenz(a)anthracene (DMBA)-induced breast cancer in gnotobiotic rats was investigated. Germ-free rats were associated with a defined lignan-converting consortium (Clostridium saccharogumia, Blautia producta, Eggerthella lenta, and Lactonifactor longoviformis). The rats colonized with lignan-converting bacteria consortium (LCC) were fed a lignan-rich flaxseed diet and breast cancer was chemical induced. Identically treated germ-free rats served as control. All bacteria of the consortium successfully colonized the intestine of the LCC rats. The plant lignan SDG was converted into the enterolignans ED and EL in the LCC rats but not in the germ-free rats. This transformation did not influence cancer incidence but significantly decreased tumor numbers per tumor-bearing rat, and tumor size. Cell proliferation was significantly inhibited and apoptosis was significantly induced in LCC rats. No differences between LCC and control rats were observed in the expression of the genes encoding the estrogen receptors (ERα and ERβ) and G-coupled protein receptor 30 (GPR30). Similar findings were observed for both insulin-like growth factor 1 (IGF-1) and epidermal growth factor receptor (EGFR) genes involved in tumor growth. Proteome analysis revealed that 24 proteins were differentially expressed in tumor tissue from LCC and germ-free. RanBP-type and C3HC4-type zinc finger-containing protein 1 (RBCK1) and poly(rC)-binding protein 1 (PBCP1) were down-regulated by 3.2- and 2.0-fold, respectively. These proteins are associated with cell proliferation. The activity of selected enzymes involved in the degradation of oxidants in plasma and liver was significantly increased in the LCC rats. However, plasma and liver concentrations of reduced glutathione (non-enzymatic antioxidant) and malondialdehyde (oxidative stress marker) did not differ between the groups. In conclusion, the bacterial conversion of plant lignan to enterolignans beneficially influences their anti-cancer effect. However, the mechanisms involved in these effects remain elusive.}, language = {en} } @phdthesis{Muehlenbruch2013, author = {M{\"u}hlenbruch, Kristin}, title = {Updating the german diabetes risk score - model extensions, validation and reclassification}, address = {Potsdam}, pages = {131 S.}, year = {2013}, language = {en} } @phdthesis{Schumann2013, author = {Schumann, Sara}, title = {Influence of intestinal inflammation on bacterial protein expression in monoassociated mice}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-67757}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Background: Increased numbers of intestinal E. coli are observed in inflammatory bowel disease, but the reasons for this proliferation and it exact role in intestinal inflammation are unknown. Aim of this PhD-project was to identify E. coli proteins involved in E. coli's adaptation to the inflammatory conditions in the gut and to investigate whether these factors affect the host. Furthermore, the molecular basis for strain-specific differences between probiotic and harmful E. coli in their response to intestinal inflammation was investigated. Methods: Using mice monoassociated either with the adherent-invasive E. coli (AIEC) strain UNC or the probiotic E. coli Nissle, two different mouse models of intestinal inflammation were analysed: On the one hand, severe inflammation was induced by treating mice with 3.5\% dextran sodium sulphate (DSS). On the other hand, a very mild intestinal inflammation was generated by associating interleukin 10-deficient (IL-10-/-) mice with E. coli. Differentially expressed proteins in the E. coli strains collected from caecal contents of these mice were identified by two-dimensional fluorescence difference gel electrophoresis. Results DSS-experiment: All DSS-treated mice revealed signs of a moderate caecal and a severe colonic inflammation. However, mice monoassociated with E. coli Nissle were less affected. In both E. coli strains, acute inflammation led to a downregulation of pathways involved in carbohydrate breakdown and energy generation. Accordingly, DSS-treated mice had lower caecal concentrations of bacterial fermentation products than the control mice. Differentially expressed proteins also included the Fe-S cluster repair protein NfuA, the tryptophanase TnaA, and the uncharacterised protein YggE. NfuA was upregulated nearly 3-fold in both E. coli strains after DSS administration. Reactive oxygen species produced during intestinal inflammation damage Fe-S clusters and thereby lead to an inactivation of Fe-S proteins. In vitro data indicated that the repair of Fe-S proteins by NfuA is a central mechanism in E. coli to survive oxidative stress. Expression of YggE, which has been reported to reduce the intracellular level of reactive oxygen species, was 4- to 8-fold higher in E. coli Nissle than in E. coli UNC under control and inflammatory conditions. In vitro growth experiments confirmed these results, indicating that E. coli Nissle is better equipped to cope with oxidative stress than E. coli UNC. Additionally, E. coli Nissle isolated from DSS-treated and control mice had TnaA levels 4- to 7-fold higher than E. coli UNC. In turn, caecal indole concentrations resulting from cleavage of tryptophan by TnaA were higher in E. coli Nissle- associated control mice than in the respective mice associated with E. coli UNC. Because of its anti-inflammatory effect, indole is hypothesised to be involved in the extension of the remission phase in ulcerative colitis described for E. coli Nissle. Results IL-10-/--experiment: Only IL-10-/- mice monoassociated with E. coli UNC for 8 weeks exhibited signs of a very mild caecal inflammation. In agreement with this weak inflammation, the variations in the bacterial proteome were small. Similar to the DSS-experiment, proteins downregulated by inflammation belong mainly to the central energy metabolism. In contrast to the DSS-experiment, no upregulation of chaperone proteins and NfuA were observed, indicating that these are strategies to overcome adverse effects of strong intestinal inflammation. The inhibitor of vertebrate C-type lysozyme, Ivy, was 2- to 3-fold upregulated on mRNA and protein level in E. coli Nissle in comparison to E. coli UNC isolated from IL-10-/- mice. By overexpressing ivy, it was demonstrated in vitro that Ivy contributes to a higher lysozyme resistance observed for E. coli Nissle, supporting the role of Ivy as a potential fitness factor in this E. coli strain. Conclusions: The results of this PhD-study demonstrate that intestinal bacteria sense even minimal changes in the health status of the host. While some bacterial adaptations to the inflammatory conditions are equal in response to strong and mild intestinal inflammation, other reactions are unique to a specific disease state. In addition, probiotic and colitogenic E. coli differ in their response to the intestinal inflammation and thereby may influence the host in different ways.}, language = {en} } @phdthesis{Slezak2013, author = {Slezak, Kathleen}, title = {Impact of intestinal bacteria on the anatomy and physiology of the intestinal tract in the PRM/Alf mouse model}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-68946}, school = {Universit{\"a}t Potsdam}, year = {2013}, abstract = {Introduction: Intestinal bacteria influence gut morphology by affecting epithelial cell proliferation, development of the lamina propria, villus length and crypt depth [1]. Gut microbiota-derived factors have been proposed to also play a role in the development of a 30 \% longer intestine, that is characteristic of PRM/Alf mice compared to other mouse strains [2, 3]. Polyamines and SCFAs produced by gut bacteria are important growth factors, which possibly influence mucosal morphology, in particular villus length and crypt depth and play a role in gut lengthening in the PRM/Alf mouse. However, experimental evidence is lacking. Aim: The objective of this work was to clarify the role of bacterially-produced polyamines on crypt depth, mucosa thickness and epithelial cell proliferation. For this purpose, C3H mice associated with a simplified human microbiota (SIHUMI) were compared with mice colonized with SIHUMI complemented by the polyamine-producing Fusobacterium varium (SIHUMI + Fv). In addition, the microbial impact on gut lengthening in PRM/Alf mice was characterized and the contribution of SCFAs and polyamines to this phenotype was examined. Results: SIHUMI + Fv mice exhibited an up to 1.7 fold higher intestinal polyamine concentration compared to SIHUMI mice, which was mainly due to increased putrescine concentrations. However, no differences were observed in crypt depth, mucosa thickness and epithelial proliferation. In PRM/Alf mice, the intestine of conventional mice was 8.5 \% longer compared to germfree mice. In contrast, intestinal lengths of C3H mice were similar, independent of the colonization status. The comparison of PRM/Alf and C3H mice, both associated with SIHUMI + Fv, demonstrated that PRM/Alf mice had a 35.9 \% longer intestine than C3H mice. However, intestinal SCFA and polyamine concentrations of PRM/Alf mice were similar or even lower, except N acetylcadaverine, which was 3.1-fold higher in PRM/Alf mice. When germfree PRM/Alf mice were associated with a complex PRM/Alf microbiota, the intestine was one quarter longer compared to PRM/Alf mice colonized with a C3H microbiota. This gut elongation correlated with levels of the polyamine N acetylspermine. Conclusion: The intestinal microbiota is able to influence intestinal length dependent on microbial composition and on the mouse genotype. Although SCFAs do not contribute to gut elongation, an influence of the polyamines N acetylcadaverine and N acetylspermine is conceivable. In addition, the study clearly demonstrated that bacterial putrescine does not influence gut morphology in C3H mice.}, language = {en} } @phdthesis{Khalil2013, author = {Khalil, Mahmoud Abd Elhamid}, title = {Improvement of stability and bioavailability of lutein and lutein ester in emulsion-based delivery systems}, address = {Potsdam}, pages = {145 S.}, year = {2013}, language = {en} } @phdthesis{Keipert2011, author = {Keipert, Susanne}, title = {The effects of mitochondrial uncoupling in skeletal muscle on lifespan, substrate and energy metabolism in mice}, address = {Potsdam}, pages = {75 S.}, year = {2011}, language = {en} } @phdthesis{Freudenberg2011, author = {Freudenberg, Anne}, title = {Effects of high-protein diets and leucine supplementation on the metabolic syndrome in mice}, address = {Potsdam}, pages = {80 S.}, year = {2011}, language = {en} } @phdthesis{Riedel2011, author = {Riedel, Katja}, title = {Elucidation of the epithelial sodium channel as a salt taste receptor candidate and search for novel salt taste receptor candidates}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-58764}, school = {Universit{\"a}t Potsdam}, year = {2011}, abstract = {Salty taste has evolved to maintain electrolyte homeostasis, serving as a detector for salt containing food. In rodents, salty taste involves at least two transduction mechanisms. One is sensitive to the drug amiloride and specific for Na+, involving epithelial sodium channel (ENaC). A second rodent transduction pathway, which is triggered by various cations, is amiloride insensitive and not almost understood to date. Studies in primates showed amiloride-sensitive as well as amiloride-insensitive gustatory responses to NaCl, implying a role of both salt taste transduction pathways in humans. However, sensory studies in humans point to largely amiloride-insensitive sodium taste perception. An involvement of ENaC in human sodium taste perception was not shown, so far. In this study, ENaC subunit protein and mRNA could be localized to human taste bud cells (TBC). Thus, basolateral αβγ-ENaC ion channels are likely in TBC of circumvallate papillae, possibly mediating basolateral sodium entry. Similarly, basolateral βγ-ENaC might play a role in fungiform TBC. Strikingly, δ-ENaC subunit was confined to taste bud pores of both papillae, likely mediating gustatory sodium entry in TBC, either apical or paracellular via tight junctions. However, regional separation of δ-ENaC and βγ-ENaC in fungiform and circumvallate TBC indicate the presence of unknown interaction partner necessary to assemble into functional ion channels. However, screening of a macaque taste tissue cDNA library did neither reveal polypeptides assembling into a functional cation channel by interaction with δ-ENaC or βγ-ENaC nor ENaC independent salt taste receptor candidates. Thus, ENaC subunits are likely involved in human taste transduction, while exact composition and identity of an amiloride (in)sensitive salt taste receptors remain unclear. Localization of δ-ENaC in human taste pores strongly suggests a role in human taste transduction. In contrast, δ-ENaC is classified as pseudogene Scnn1d in mouse. However, no experimental detected sequences are annotated, while evidences for parts of Scnn1d derived mRNAs exist. In order to elucidate if Scnn1d is possibly involved in rodent salt taste perception, Scnn1d was evaluated in this study to clarify if Scnn1d is a gene or a transcribed pseudogene in mice. Comparative mapping of human SCNN1D to mouse chromosome 4 revealed complete Scnn1d sequence as well as its pseudogenization by Mus specific endogenous retroviruses. Moreover, tissue specific transcription of unitary Scnn1d pseudogene was found in mouse vallate papillae, kidney and testis and led to identification of nine Scnn1d transcripts. In vitro translation experiments showed that Scnn1d transcripts are coding competent for short polypeptides, possibly present in vivo. However, no sodium channel like function or sodium channel modulating activity was evident for Scnn1d transcripts and/or derived polypeptides. Thus, an involvement of mouse δ-ENaC in sodium taste transduction is unlikely and points to species specific differences in salt taste transduction mechanisms.}, language = {en} } @phdthesis{Kirchner2010, author = {Kirchner, Henriette}, title = {The ghrelin system links dietary lipids with the endocrine control of energy homeostasis}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-52393}, school = {Universit{\"a}t Potsdam}, year = {2010}, abstract = {Ghrelin is a unique hunger-inducing stomach-borne hormone. It activates orexigenic circuits in the central nervous system (CNS) when acylated with a fatty acid residue by the Ghrelin O-acyltransferase (GOAT). Soon after the discovery of ghrelin a theoretical model emerged which suggests that the gastric peptide ghrelin is the first "meal initiation molecule}, language = {en} } @phdthesis{Moerbt2010, author = {M{\"o}rbt, Nora}, title = {Differential proteome analysis of human lung epithelial cells following exposure to aromatic volatile organic compounds}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-49257}, school = {Universit{\"a}t Potsdam}, year = {2010}, abstract = {The widespread usage of products containing volatile organic compounds (VOC) has lead to a general human exposure to these chemicals in work places or homes being suspected to contribute to the growing incidence of environmental diseases. Since the causal molecular mechanisms for the development of these disorders are not completely understood, the overall objective of this thesis was to investigate VOC-mediated molecular effects on human lung cells in vitro at VOC concentrations comparable to exposure scenarios below current occupational limits. Although differential expression of single proteins in response to VOCs has been reported, effects on complex protein networks (proteome) have not been investigated. However, this information is indispensable when trying to ascertain a mechanism for VOC action on the cellular level and establishing preventive strategies. For this study, the alveolar epithelial cell line A549 has been used. This cell line, cultured in a two-phase (air/liquid) model allows the most direct exposure and had been successfully applied for the analysis of inflammatory effects in response to VOCs. Mass spectrometric identification of 266 protein spots provided the first proteomic map of A549 cell line to this extent that may foster future work with this frequently used cellular model. The distribution of three typical air contaminants, monochlorobenzene (CB), styrene and 1,2 dichlorobenzene (1,2-DCB), between gas and liquid phase of the exposure model has been analyzed by gas chromatography. The obtained VOC partitioning was in agreement with available literature data. Subsequently the adapted in vitro system has been successfully employed to characterize the effects of the aromatic compound styrene on the proteome of A549 cells (Chapter 4). Initially, the cell toxicity has been assessed in order to ensure that most of the concentrations used in the following proteomic approach were not cytotoxic. Significant changes in abundance and phosphorylation in the total soluble protein fraction of A549 cells have been detected following styrene exposure. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. Validation experiments on protein and transcript level confirmed the results of the 2-DE experiments. From the results, two main cellular pathways have been identified that were induced by styrene: the cellular oxidative stress response combined with moderate pro-apoptotic signaling. Measurement of cellular reactive oxygen species (ROS) as well as the styrene-mediated induction of oxidative stress marker proteins confirmed the hypothesis of oxidative stress as the main molecular response mechanism. Finally, adducts of cellular proteins with the reactive styrene metabolite styrene 7,8 oxide (SO) have been identified. Especially the SO-adducts observed at both the reactive centers of thioredoxin reductase 1, which is a key element in the control of the cellular redox state, may be involved in styrene-induced ROS formation and apoptosis. A similar proteomic approach has been carried out with the halobenzenes CB and 1,2-DCB (Chapter 5). In accordance with previous findings, cell toxicity assessment showed enhanced toxicity compared to the one caused by styrene. Significant changes in abundance and phosphorylation of total soluble proteins of A549 cells have been detected following exposure to subtoxic concentrations of CB and 1,2-DCB. All proteins have been identified using mass spectrometry and the main cellular functions have been assigned. As for the styrene experiment, the results indicated two main pathways to be affected in the presence of chlorinated benzenes, cell death signaling and oxidative stress response. The strong induction of pro-apoptotic signaling has been confirmed for both treatments by detection of the cleavage of caspase 3. Likewise, the induction of redox-sensitive protein species could be correlated to an increased cellular level of ROS observed following CB treatment. Finally, common mechanisms in the cellular response to aromatic VOCs have been investigated (Chapter 6). A similar number (4.6-6.9\%) of all quantified protein spots showed differential expression (p<0.05) following cell exposure to styrene, CB or 1,2-DCB. However, not more than three protein spots showed significant regulation in the same direction for all three volatile compounds: voltage-dependent anion-selective channel protein 2, peroxiredoxin 1 and elongation factor 2. However, all of these proteins are important molecular targets in stress- and cell death-related signaling pathways.}, language = {en} } @phdthesis{Wohlgemuth2010, author = {Wohlgemuth, Steffen}, title = {Microbial and host factors associated with chronic intestinal inflammation of the Interleukin-10 deficient mouse}, address = {Potsdam}, pages = {IX, 125 Bl. : Ill., graph. Darst.}, year = {2010}, language = {en} } @phdthesis{Gerber2010, author = {Gerber, Chimgee Baasanjav}, title = {Detection and identification of genotoxicant from brassica plants}, address = {Potsdam}, pages = {191 S.}, year = {2010}, language = {en} } @phdthesis{Chadt2009, author = {Chadt, Alexandra}, title = {Functional characterization of a novel candidate gene for obesity, Tbc 1d1}, address = {Potsdam}, pages = {133 S.}, year = {2009}, language = {en} } @phdthesis{RadeKukic2009, author = {Rade-Kukic, Koraljka}, title = {Interactionof ß-lactoglobulin with sinigin and allyl-isothiocyanate - effect on protein's physico- chemical and functional properties}, address = {Potsdam}, pages = {123, VIII S.}, year = {2009}, language = {en} } @phdthesis{Henze2009, author = {Henze, Andrea}, title = {Chronic kidney disease and type 2 diabetes mellitus as factors influencing retinol-binding protein 4}, address = {Potsdam}, pages = {XI, 143 S. : Ill., graph. Darst.}, year = {2009}, language = {en} } @phdthesis{Kucia2009, author = {Kucia, Marzena}, title = {Impact of a high protein diet on maternal health status, milk composition and rearing success during pregnancy and lactation of two mouse genotypes}, address = {Potsdam}, pages = {X, 109 Bl. : graph. Darst.}, year = {2009}, language = {en} } @phdthesis{ElSaadany2009, author = {El-Saadany, Mohamed Abdel Meged Marawan}, title = {Protective effect of dietary antioxidants and plant extracts on acute inflammation and hepatotoxicity in vitro}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31585}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {Dietary antioxidants are believed to play an important role in the prevention and treatment of a variety of diseases associated with oxidative stress. Although there is a wide range of dietary antioxidants, the bulk of the research to date has been focused on the nutrient antioxidants vitamin C, E, and carotenoids. Certain relatively uncommon antioxidants such as lipoic acid (LA), and phenolic compounds such as (-)-epicatechin (EC), (-)-epigallocatechin (EGC), (-)-epicatechin gallate (ECG), and (-)-epigallocatechin gallate (EGCG), have not been extensively investigated although they may exert greater antioxidant potency than that of carotenoids and vitamins. Extracts from selected plants and plant byproducts may represent rich sources for one or more of such antioxidants and therefore exhibit higher effects than a single antioxidant due to the synergistic effects produced between such antioxidants. However, in the last decade a number of epidemiological, animal and in vitro studies have suggested a protective and therapeutic potency of these antioxidants in a broad range of diseases such as cancer, diabetes, atherosclerosis, cataract and acute and chronic neurological disorders. Inflammation, the response of the host toward any infection or injury, plays a central role in the development of many chronic diseases. Several evidences demonstrated the rise of different types of cancer from sites of inflammation. This suggests that active oxygen species and some cytokines generated in the inflamed tissues can cause injury to DNA and ultimately lead to carcinogenesis. Diethylnitrosamine (DEN) is one of the most important environmental carcinogens, present in a variety of foods, alcoholic beverages, tobacco smoke and it can be synthesized endogenously. In addition to the liver it can induce carcinogenesis in other organs like kidney, trachea, lung, esophagus, fore stomach, and nasal cavity. Several epidemiological and laboratory studies indicate that nitroso compounds including DEN may induce hyperplasia and chronic inflammation which is closely associated with the development of hepatocellular carcinoma. Despite increasing evidence on the potential of antioxidants in modulating the etiology of chronic diseases, little is known about their role in inflammation and acute phase response (APR). Therefore the aim of the present work was to study the protective effect of water and solvent extracts of eight plant and plant byproducts including green tea, artichoke, spinach, broccoli, onion and eggplant, orange and potato peels as well as eight antioxidants agents including EC, EGC, ECG, EGCG, ascorbic acid (AA), acetylcysteine (NAC), α-LA, and alpha-tocopherol (α-TOC) toward acute inflammation induced by interleukin-6 (IL-6) and hepatotoxicity induced by DEN in vitro. The negative acute phase proteins (APP), transthyretin (TTR) and retinol-binding protein (RBP) were used as inflammatory biomarkers analyzed by ELISA, whereas neutral red assay was used for evaluating the cytotoxicity. All experiments were performed in vitro using human hepatocarcinoma cell line (HepG2). Additionally the antioxidant activity was measured by TEAC and FRAP assays, phenolic content was measured by Folin-Ciocalteu and characterized by HPLC. Moreover, the microheterogeneity of TTR was detected using immunoprecipitation assay combined with SELDI-TOF MS. Results of present study showed that HepG2 cells provide a simple, sensitive in vitro system for studying the regulation of the negative APP, TTR and RBP under free and inflammatory condition. IL-6, a potent proinflammatory cytokine, in a concentration of 25 ng/ml was able to reduce TTR and RBP secretion by approximately 50-60\% after 24h of incubation. With exception of broccoli and water extract of onion which showed pro-inflammatory effects in this study, all other plant extracts, at specific concentrations, were able to elevate TTR secretion in normal condition and even under treatment of IL-6 where the effect was quite lower. Green tea followed by artichoke and potato peel exhibited the highest elevation in TTR concentration which reached 1.1 and 2.5 folds of control in presence and absences of IL-6 respectively. In general Plant extracts were ordered according their anti-inflammatory potency as following: in water extracts; green tea > artichoke > potato peel > orange peel > spinach > eggplant peel, where in solvent extracts; green tea > artichoke > potato peel > spinach > eggplant peel > onion > orange peel. The antiinflammatory effect of water extracts of green tea, artichoke and orange peel were significantly higher than their corresponding solvent extracts whereas water extracts of eggplant-, potato peels and spinach showed lower effect than their solvent extracts. On the other hand α-LA followed by EGCG and ECG exhibited the highest elevation in TTR concentration compared to other antioxidants. The relation between the anti-inflammatory potential and antioxidants activity and phenolic content for the investigated substances was generally weak. This may suggest the involvement of other mechanisms than antioxidants properties for the observed effect. TTR secreted by HepG2 cells has a molecular structure quite similar to the purified standard and serum TTR in which all the three main variants are contained including native, S-cystinylated and Sglutathionylated TTR. Interestingly, a variant with molecular mass of 13453.8 + 8.3 Da has been detected only in TTR secreted by HepG2. Among all investigated antioxidants and plant extracts, six substances were able to elevate the native preferable TTR variant. The potency of these substances can be ordered as following α-LA > NAC > onion > AA > EGCG > green tea. A weak correlation between elevation on TTR and shifting to the native form was observed. Similar weak correlation has also been observed between antioxidants activity and elevation in native TTR. Although DEN was able to induce cell death in a concentration dependent manner, it requires considerably higher concentrations for its effects especially after 24h. This may be attributed to a lack in cytochrome P450 enzymes produced by HepG2. At selected concentrations some antioxidants and plant extracts significantly attenuate DEN cytotoxicity as following: spinach > α-LA > artichoke > orange peel > eggplant peel > α-TOC > onion > AA. Contrary all other substances especially green tea, broccoli, potato peel, and ECG stimulate DEN toxicity. In conclusion, this study demonstrated that selected antioxidants and plant extracts may attenuate the inflammatory process, not only by their antioxidants potency but also by other mechanisms which remain unclear. They may also play a vital role on stabilizing the tetramic structure of TTR and thereby prevent amyloidosis diseases. Lipoic acid represents in this study unique function against inflammation and hepatotoxicity. Despite the protective effect demonstrated by investigated substances, attention should also be given to the pro-oxidant and potential cytotoxic effects produced at higher concentrations.}, language = {en} } @phdthesis{Frey2009, author = {Frey, Simone K.}, title = {Investigations on extra- and intracellular retinol-binding proteins}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-31428}, school = {Universit{\"a}t Potsdam}, year = {2009}, abstract = {The fat-soluble vitamin A, which is chemically referred to retinol (ROH), is known to be essential for the process of vision, the immune system but also for cell differentiation and proliferation. Recently, ROH itself has been reported to be involved in adipogenesis and a ROH transport protein, the retinol-binding protein 4 (RBP4), in insulin resistance and type 2 diabetes. However, there is still considerable scientific debate about this relation. With the increasing amount of studies investigating the relation of ROH in obesity and type 2 diabetes, basic research is an essential prerequisite for interpreting these results. This thesis enhances the knowledge on this relation by reviewing ROH metabolism on extra- and intracellular level. Aim 1: In the blood stream ROH is transported in a complex with RBP4 and a second protein, transthyretin (TTR), to the target cells. The levels of RBP4 and TTR are influenced by several factors but mainly by liver and kidney function. The reason for that is that liver and the kidneys are the sites of RBP4 synthesis and catabolism, respectively. Interestingly, obesity and type 2 diabetes involve disorders of the liver and the kidneys. Therefore the aim was to investigate factors that influence RBP4 and TTR levels in relation to obesity and type 2 diabetes (Part 1). Aim 2: Once arrived in the target cell ROH is bound to cellular retinol-binding protein type I (CRBP-I) and metabolised: ROH can either be stored as retinylesters or it can be oxidised to retinoic acid (RA). By acting as a transcription factor in the nucleus RA may influence processes such as adipogenesis. Therefore vitamin A has been postulated to be involved in obesity and type 2 diabetes. CRBP-I is known to mediate the storage of ROH in the liver, but the extra-hepatic metabolism and the functions of CRBP-I are not well known. This has been investigated in Part 2 of this work. Material \& Methods: RBP4 and TTR levels were investigated by ELISA in serum samples of human subjects with overweight, type 2 diabetes, kidney or liver dysfunction. Molecular alterations of the RBP4 and TTR protein structure were analysed by MALDI-TOF mass spectrometry. The functions of intracellular CRBP-I were investigated in CRBP-I knock-out mice in liver and extra-hepatic tissues by measuring ROH levels as well as the levels of its storage form, the retinylesters, using reverse phase HPLC. The postprandial uptake of ROH into tissues was analysed using labelled ROH. The mRNA levels of enzymes that metabolize ROH were examined by real-time polymerase chain reaction (RCR). Results: The previous published results showing increased RBP4 levels in type 2 diabetic patients could not be confirmed in this work. However, it could be shown that during kidney dysfunction RBP4 levels are increased and that RBP4 and TTR levels are decreased during liver dysfunction. The important new finding of this work is that increased RBP4 levels in type 2 diabetic mice were increased when kidney function was decreased. Thus an increase in RBP4 levels in type 2 diabetes may be the effect of a reduced kidney function which is common in type 2 diabetes. Interestingly, during severe kidney dysfunction the molecular structure of RBP4 and TTR was altered in a specific manner which was not the case during liver diseases and type 2 diabetes. This underlines the important function of the kidneys in RBP4 metabolism. CRBP-I has been confirmed to be responsible for the ROH storage in the liver since CRBP-I knock-out mice had decreased ROH and retinylesters (the storage form of ROH) levels in the liver. Interestingly, in the adipose tissue (the second largest ROH storage tissue in the body) ROH and retinylesters levels were higher in the CRBP-I knock-out compared to the wild-type mice. It could be shown in this work that a different ROH binding protein, cellular retinol-binding protein type III, is upregulated in CRBP-I knock-out mice. Moreover enzymes were identified which mediate very efficiently ROH esterification in the adipose tissue of the knock-out mice. In the pancreas there was a higher postprandial ROH uptake in the CRBP-I knock-out compard to wild-type mice. Even under a vitamin A deficient diet the knock-out animals had ROH and retinylesters levels which were comparable to wild-type animals. These results underline the important role of ROH for insulin secretion in the pancreas. Summing up, there is evidence that RBP4 levels are more determined by kidney function than by type 2 diabetes and that specific molecular modifications occur during kidney dysfunction. The results in adipose tissue and pancreas of CRBP-I knock-out mice support the hypothesis that ROH plays an important role in glucose and lipid metabolism.}, language = {en} } @phdthesis{Henderson2007, author = {Henderson, Gemma}, title = {Development of bacterial food preparations with tumour-prophylactic potential}, address = {Potsdam}, pages = {IV, 90 Bl. : graph. Darst.}, year = {2007}, language = {en} } @phdthesis{Appl2007, author = {Appl, Thomas}, title = {Neurochemical and functional characterisation of the Melanin-concentrating hormone system in the rat brain}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-14604}, school = {Universit{\"a}t Potsdam}, year = {2007}, abstract = {The central melanin-concentrating hormone (MCH) system has been intensively studied for its involvement in the regulation of feeding behaviour and body weight regulation. The importance of the neuropeptide MCH in the control of energy balance has been underlined by MCH knock out and Melanin-concentrating hormone receptor subtype 1 (MCHR-1) knock-out animals. The anorectic and anti-obesity effects of selective MCHR-1 antagonists have confirmed the notion that pharmacological blockade of MCHR-1 is a potential therapeutic approach for obesity. First aim of this work is to study the neurochemical "equipment" of MCHR-1 immunoreactive neurons by double-labelling immunohistochemistry within the rat hypothalamus. Of special interest is the neuroanatomical identification of other hypothalamic neuropeptides that are co-distributed with MCHR-1. A second part of this study deals with the examination of neuronal activation patterns after pharmacological or physiological, feeding-related stimuli and was introduced to further understand central regulatory mechanisms of the MCH system. In the first part of work, I wanted to neurochemically characterize MCHR-1 immunoreactive neurons in the rat hypothalamus for colocalisation with neuropeptides of interest. Therefore I performed an immunohistochemical colocalisation study using a specific antibody against MCHR-1 in combination with antibodies against hypothalamic neuropeptides. I showed that MCHR-1 immunoreactivity (IR) was co-localised with orexin A in the lateral hypothalamus, and with adrenocorticotropic hormone and neuropeptide Y in the arcuate nucleus. Additionally, MCHR-1 IR was co-localised with the neuropeptides vasopressin and oxytocin in magnocellular neurons of the supraoptic and paraventricular hypothalamic nucleus and corticotrophin releasing hormone in the parvocellular division of the paraventricular hypothalamic nucleus. Moreover, for the first time MCHR-1 immunoreactivity was found in both the adenohypophyseal and neurohypophyseal part of the rat pituitary. These results provide the neurochemical basis for previously described potential physiological actions of MCH at its target receptor. In particular, the MCHR-1 may be involved not only in food intake regulation, but also in other physiological actions such as fluid regulation, reproduction and stress response, possibly through here examined neuropeptides. Central activation patterns induced by pharmacological or physiological stimulation can be mapped using c-Fos immunohistochemistry. In the first experimental design, central administration (icv) of MCH in the rat brain resulted in acute and significant increase of food and water intake, but this animal treatment did not induce a specific c-Fos induction pattern in hypothalamic nuclei. In contrast, sub-chronic application of MCHR-1 antagonist promoted a significant decrease in food- and water intake during an eight day treatment period. A qualitative analysis of c-Fos immunohistochemistry of sections derived from MCHR-1 antagonist treated animals showed a specific neuronal activation in the paraventricular nucleus, the supraoptic nucleus and the dorsomedial hypothalamus. These results could be substantiated by quantitative evaluation of an automated, software-supported analysis of the c-Fos signal. Additionally, I examined the activation pattern of rats in a restricted feeding schedule (RFS) to identify pathways involved in hunger and satiety. Animals were trained for 9 days to feed during a three hour period. On the last day, food restricted animals was also allowed to feed for the three hours, while food deprived (FD) animals did not receive food. Mapping of neuronal activation showed a clear difference between stareved (FD) and satiated (FR) rats. FD animals showed significant induction of c-Fos in forebrain regions, several hypothalamic nuclei, amygdaloid thalamus and FR animals in the supraoptic nucleus and the paraventricular nucleus of the hypothalamus, and the nucleus of the solitary tract. In the lateral hypothalamus of FD rats, c-Fos IR showed strong colocalisation for Orexin A, but no co-staining for MCH immunoreactivity. However, a large number of c-Fos IR neurons within activated regions of FD and FR animals was co-localised with MCHR-1 within selected regions. To conclude, the experimental set-up of scheduled feeding can be used to induce a specific hunger or satiety activation pattern within the rat brain. My results show a differential activation by hunger signals of MCH neurons and furthermore, demonstrates that MCHR-1 expressing neurons may be essential parts of downstream processing of physiological feeding/hunger stimuli. In the final part of my work, the relevance of here presented studies is discussed with respect to possible introduction of MCHR-1 antagonists as drug candidates for the treatment of obesity.}, language = {en} }