47104
2006
2006
eng
705
713
9
8
50
article
Wiley
Weinheim
1
--
--
--
Determining the binding affinities of phenolic compounds to proteins by quenching of the intrinsic tryptophan fluorescence
The noncovalent binding of selected phenolic compounds (chlorogenic-, ferutic-, gallic acid, quercetin, rutin, and isoquercetin) to proteins (HSA, BSA, soy glycinin, and lysozyme) was studied by an indirect method applying the quenching of intrinsic tryptophan fluorescence. From the data obtained, the binding constants were calculated by nonlinear regression (one site binding; y = Bx/k + x). It has been reported that tannins inhibit human salivary amylase and that these complexes may reduce the development of cariogenic plaques. Further, amylase contains two tryptophan residues in its active site. Therefore, in a second part of the study involving 31 human subjects, evidence was sought for noncovalent interactions between the phenols of green tea and saliva proteins as measured by the fluorescence intensity. Amylase activity was determined before and after the addition of green tea to saliva of 31 subjects. Forty percent of the subjects showed an increase in amylase activity contrary to studies reporting only a decrease in activity. The interactions of tannin with amylase result in a decrease of its activity. It still remains to be elucidated why amylase does not react uniformly under conditions of applying green tea to saliva. Further, in terms of using phenols as caries inhibitors this finding should be of importance.
Molecular nutrition & food research : bioactivity, chemistry, immunology, microbiology, safety, technology
10.1002/mnfr.200600013
16835869
1613-4125
wos:2006
WOS:000240025900004
Rawel, HM (reprint author), Univ Potsdam, Dept Physiol & Pathophysiol, Inst Nutr Sci, Arthur Scheunert Allee 114-116, D-14558 Bergholz Rehbrucke, Germany., rawel@uni-potsdam.de
importub
2020-06-10T12:36:15+00:00
filename=package.tar
a344269a906dc8cd359d0a844ffa8c45
false
true
Harshadrai Manilal Rawel
Simone K. Frey
Karina Meidtner
Jürgen Kroll
Florian J. Schweigert
eng
uncontrolled
amylase activity
eng
uncontrolled
green tea phenols
eng
uncontrolled
protein-phenol binding
eng
uncontrolled
saliva proteins
eng
uncontrolled
tryptophan quenching
Naturwissenschaften und Mathematik
Institut für Ernährungswissenschaft
Referiert
Import
31648
2009
2009
eng
article
1
--
--
--
Effect of renal replacement therapy on retinol-binding protein 4 isoforms
Background: Retinol-binding protein 4 (RBP4) levels are elevated in the serum of patients with kidney dysfunction. We recently showed that RBP4 isoforms including apo-RBP4 (RBP4 not bound to retinol) and RBP4 truncated at the C-terminus (RBP4-L, RBP4-LL) are increased in the serum of patients with kidney diseases but not in serum of patients with various liver diseases. The aim of this study was to investigate the effect of renal replacement therapy on RBP4 isoforms. Methods: We investigated serum levels of RBP4, apo-RBP4, holo-RBP4, RBP4-L, RBP4-LL, retinol and transthyretin (TTR) in 18 hemodialysis (HD) patients, 30 patients after renal transplantation (RTx) and in 35 healthy controls. RBP4 and TTR levels were measured by enzyme-linked immunosorbent assay, apo- and holo-RBP4 by native electrophoresis, retinol by high performance liquid chromatography and RBP4-L and RBP4-LL were analyzed by mass spectrometry. Results: HD and RTx patients had elevated RBP4, apo-RBP4 and RBP4-LL levels compared to controls. RTx patients had elevated amounts of RBP4-L compared to controls and elevated RBP4 and apo-RBP4 levels compared to HD patients. Conclusion: The results demonstrate a strong correlation between kidney function and RBP4 isoforms and provide data for investigating the relation of RBP4 and insulin resistance in these patients.
http://www.sciencedirect.com/science/journal/00098981
10.1016/j.cca.2008.11.008
0009-8981
allegro:1991-2014
10107981
Clinica chimica acta. - ISSN 0009-8981. - 401 (2009), 1-2, S. 46 - 50
Simone K. Frey
Andrea Henze
Britta Nagl
Jens Raila
Alexandra Scholze
Martin Tepel
Florian J. Schweigert
Walter Zidek
Institut für Ernährungswissenschaft
Referiert
31649
2009
2009
eng
article
1
--
--
--
Factors that influence retinol-binding protein 4-transthyretin interaction are not altered in overweight subjects and overweight subjects with type 2 diabetes mellitus
Retinol-binding protein 4 (RBP4) is an adipokine bound in plasma to transthyretin (TTR), which prevents its glomerular filtration and subsequent catabolism in the kidney. Alterations of this interaction have been Suggested to be implicated in the elevation of RBP4 that are thought to contribute to the development Of insulin resistance associated with obesity and type 2 diabetes mellitus (T2DM). However, the factors linking RBP4 to TTR in humans are not clear. Therefore, this Study evaluated parameters influencing the RBP4-TTR interaction and their relation to obesity and T2DM. The RBP4 and TTR levels were quantified in plasma of 16 lean controls, 28 overweight controls, and 14 overweight T2DM patients by enzyme-linked immunosorbent assay. Transthyretin isoforms involved in RBP4 binding were determined by linear matrix-assisted laser desorption/ionization-time of flight-mass spectrometry after RBP4 coimmunoprecipitation. Holo-RBP4 (retinol-bound) and apo-RBP4 (retinol-free) were assessed by immunoblotting using nondenaturating polyacrylamide gel electrophoresis. Plasma levels of both RBP4 and TTR did not differ among the groups of lean controls, overweight controls, and overweight T2DM subjects. Using RBP4 immunoprecipitation, 4 mass signals were observed for TTR representing native, S-cysteinylated, S-cysteinglycinylated, and S-glutathionylated TTR. No differences in peak intensity of TTR isoforms were observed among the groups. Moreover, no differences in the ratio of holo- and apo-RBP4 were evident. The results suggest that circulating RBP4 and TTR were not affected by human obesity or T2DM, which might be attributed to the absence of alterations of TTR isoforms and the ratio of holo- and apo-RBP4 that might modify the TTR-RBP4 interaction.
http://www.sciencedirect.com/science/journal/00260495
10.1016/j.metabol.2009.05.003
0026-0495
allegro:1991-2014
10107982
Metabolism. - ISSN 0026-0495. - 58 (2009), 10, S. 1386 - 1392
Simone K. Frey
Joachim Spranger
Andrea Henze
Andreas F. H. Pfeiffer
Florian J. Schweigert
Jens Raila
Institut für Ernährungswissenschaft
Referiert
31453
2010
2010
eng
article
1
--
--
--
Cellular retinol-binding protein type I (CRBP-I) regulates adipogenesis
Adipogenesis is governed by a well-documented cascade of transcription factors. However, less is known about non-transcription factors that govern early stages of adipogenesis. Here we show that cellular retinol-binding protein type I (CRBP-I), a small cytosolic binding protein for retinol and retinaldehyde, is specifically restricted to preadipocytes in white adipose tissue. The absence of CRBP-I in mice (CRBP-I-KO mice) leads to increased adiposity. Despite increased adiposity, CRBP-I-KO mice remain more glucose tolerant and insulin sensitive during high-fat-diet feeding. 3T3-L1 cells deficient in CRBP-I or mouse embryonic fibroblasts derived from CRBP-I-KO mice had increased adipocyte differentiation and triglyceride (TG) accumulation. This was due to increased expression and activity of PPAR gamma, while other transcription factor pathways in early and late differentiation remained unchanged. Conversely, the overexpression of CRBP-I in 3T3-L1 cells results in decreased TG accumulation. In conclusion, CRBP-I is a cytosolic protein specifically expressed in preadipocytes that regulates adipocyte differentiation in part by affecting PPAR gamma activity.
http://mcb.asm.org/
10.1128/Mcb.00014-10
0270-7306
allegro:1991-2014
10107738
Molecular and cellular biology. - ISSN 0270-7306. - 30 (2010), 14, S. 3412 - 3420
C. F. Zizola
Simone K. Frey
S. Jitngarmkusol
Bert Kadereit
N. Yan
Silke Vogel
Institut für Ernährungswissenschaft
Referiert
32221
2010
2010
eng
article
1
--
--
--
Alterations of retinol-binding protein 4 species in patients with different stages of chronic kidney disease and their relation to lipid parameters
Retinol-binding protein 4 (RBP4) is elevated in patients with chronic kidney disease (CKD) and has been discussed as marker of kidney function. In addition to an elevated concentration, the existence of truncated RBP4 species, RBP4-L (truncated at last C-terminal leucine) and RBP4-LL (truncated at both C-terminal leucines), has been reported in serum of hemodialysis patients. Since little is known about the occurrence of RBP4 species during the progression of CKD it was the aim of this study to analyse this possible association. The presence of RBP4, RBP4-L, RBP4- LL and transthyretin (TTR) was assessed in serum of 45 healthy controls and 52 patients with stage 2-5 of CKD using ELISA and RBP4 immunoprecipitation with subsequent MALDI-TOF-MS analysis. A reduction of glomerular filtration rate was accompanied by a gradual elevation of RBP4 serum levels and relative amounts of RBP4-LL. Correlation analysis revealed a strong association of the RBP4-TTR ratio with parameters of lipid metabolism and with diabetes-related factors. In conclusion, RBP4 serum concentration and the appearance of RBP4-LL seem to be influenced by kidney function. Furthermore, the RBP4-TTR ratio may provide diagnostic potential with regard to metabolic complications in CKD patients.
http://www.sciencedirect.com/science/journal/0006291X
10.1016/j.bbrc.2010.01.082
0006-291X
allegro:1991-2014
10108575
Biochemical and biophysical research communications. - ISSN 0006-291X. - 393 (2010), 1, S. 79 - 83
Andrea Henze
Simone K. Frey
Jens Raila
Alexandra Scholze
Joachim Spranger
Martin O. Weickert
Martin Tepel
Walter Zidek
Florian J. Schweigert
Institut für Ernährungswissenschaft
Referiert
36609
2011
2011
eng
335
342
8
5
81
article
Hogrefe
Bern
1
--
--
--
Quantification of vitamin A in palm oil using a fast and simple portable device method validation and comparison to high-performance liquid chromatography
Vitamin A deficiency continues to be a global public health problem. Fortification of oil with vitamin A is considered a cost-effective, feasible strategy to prevent this problem but quality control poses a challenge to program implementation. To overcome this, we have validated a newly developed device that quantitatively measures the content of retinyl palmitate in refined palm oil, is simple to use, and yields immediate results.
Linearity of analysis rand from 2.5-30 mg retinol equivalents (RE)/kg of palm oil, with 2.5 mg RE/kg being the determination limit; inter- and intra-assay precision ranged from 1.4-7.1 To. Comparison with a high-performance Liquid chromatography method showed high agreement between the methods (R-2 = 0.92; Limits of Agreement: -1.24 mg to 2.53 mg RE/kg), and further comparisons illustrate that the new device is useful in low resource settings. This device offers a field- and user-friendly solution to quantifying the vitamin A content in refined palm oil.
International journal for vitamin and nutrition research
10.1024/0300-9831/a000081
0300-9831
wos:2011-2013
WOS:000302840500007
Rohner, F (reprint author), GAIN, POB 55, CH-1211 Geneva, Switzerland., frohner@gainhealth.org
Fabian Rohner
Simone K. Frey
Ralf Mothes
Andrea Hurtienne
Simone Hartong
Patrice Emery Bosso
Mai Bui
Florian J. Schweigert
Christine Northrop-Clewes
eng
uncontrolled
Vitamin A
eng
uncontrolled
retinyl palmitate
eng
uncontrolled
fortification
eng
uncontrolled
monitoring
eng
uncontrolled
rapid test kit
eng
uncontrolled
palm oil
Institut für Ernährungswissenschaft
Referiert
35463
2012
2012
eng
S330
S335
6
4
33
article
International Nutrition Foundation
Boston
1
--
--
--
Validation of a user-friendly and rapid method for quantifying iodine content of salt
Background. Despite considerable progress made in the past decade through salt iodization programs, over 2 billion people worldwide still have inadequate iodine intake, with devastating consequences for brain development and intellectual capacity. To optimize these programs with regard to salt iodine content, careful monitoring of salt iodine content is essential, but few methods are available to quantitatively measure iodine concentration in a simple, fast, and safe way.
Objective. We have validated a newly developed device that quantitatively measures the content of potassium iodate in salt in a simple, safe, and rapid way.
Methods. The linearity, determination and detection limit, and inter- and intra-assay variability of this colorimetric method were assessed and the method was compared with iodometric titration, using salt samples from several countries.
Results. Linearity of analysis ranged from 5 to 75 mg/kg iodine, with I mg/kg being the determination limit; the intra- and interassay imprecision was 0.9%, 0.5%, and 0.7% and 1.5%, 1.7%, and 2.5% for salt samples with iodine contents of 17, 30, and 55 mg/kg, respectively; the interoperator imprecision for the same samples was 1.2%, 4.9%, and 4.7%, respectively. Comparison with the iodometric method showed high agreement between the methods (R-2 = 0.978; limits of agreement, -10.5 to 10.0 mg/kg).
Conclusions. The device offers a field- and user-friendly solution to quantifying potassium iodate salt content reliably. For countries that use potassium iodide in salt iodization programs, further validation is required.
Food and nutrition bulletin
0379-5721
wos:2011-2013
WOS:000313528400009
Rohner, F (reprint author), GroundWork LLC, 40B Les Landes, CH-1299 Crans Pres Celigny, Switzerland., fabian@groundworkhealth.org
Global Alliance for Improved Nutrition (GAIN) through Bill and Melinda
Gates Foundation; UK Department for International Development (DFID)
Fabian Rohner
Greg S. Garrett
Arnaud Laillou
Simone K. Frey
Ralf Mothes
Florian J. Schweigert
Lorenzo Locatelli-Rossi
eng
uncontrolled
Iodization
eng
uncontrolled
iodine
eng
uncontrolled
monitoring
eng
uncontrolled
potassium iodate
eng
uncontrolled
quality control
eng
uncontrolled
rapid test kit
eng
uncontrolled
regulatory monitoring
eng
uncontrolled
salt
Institut für Ernährungswissenschaft
Referiert
2973
2009
eng
doctoralthesis
1
2009-05-29
--
2009-05-04
Investigations on extra- and intracellular retinol-binding proteins
Untersuchungen zu extra- und intrazellulären Retinol-Bindungsproteinen
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.
Vitamin A gehört zur Gruppe der fettlöslichen Vitamine und wird chemisch als Retinol bezeichnet. Es ist essentiell für den Prozess des Sehvorgangs und der Zelldifferenzierung und kann daher bestimmte Entwicklungsprozesse wie die Bildung des Fettgewebes beeinflussen. Aufgrund seiner Fettlöslichkeit muss Retinol im Blut (= extrazellulär) sowie in der Zelle (= intrazellulär) an sogenannte Transport-Moleküle, die Retinol-bindenden Proteine (RBPs) gebunden werden. Die zwei bekanntesten Vertreter der RBPs sind das Retinol-bindende Protein 4 (RBP4) und das intrazelluläre Retinol-bindende Protein Typ I (CRBP-I). RBP4 transportiert Vitamin A im Blut von der Leber zur Zielzelle und zum Abbauorgan für Vitamin A, der Niere. CRBP-I ist in der Leber für die Speicherung von Vitamin A zuständig. In den letzten Jahren wurden neben der Beteiligung des Retinols an der Bildung des Fettgewebes auch Studien veröffentlicht, in denen ein Zusammenhang zwischen erhöhten RBP4-Werte im Blut und Typ-2-Diabetes gezeigt wurde. Bis heute ist der mögliche Zusammenhang zwischen RBP4, CRBP-I und Übergewicht nicht ausreichend erforscht. Im ersten Teil der Arbeit war daher das Ziel, Einflussfaktoren, die zu Veränderungen der RBP4-Werte im Blut führen können, zu untersuchen. Dazu wurden Blutproben von Personen mit Übergewicht und/oder Typ-2-Diabetes und Patienten mit Nierenfunktionsstörungen oder mit Leberfunktionsstörungen analysiert. Es konnte gezeigt werden, dass bereits geringe Nierenfunktionsstörungen zu erhöhten RBP4-Konzentrationen im Blut führten. Bei Typ-2-Diabetikern, die sehr oft an Nierenfunktionsstörungen leiden, war eine Erhöhung der RBP4-Konzentration mit einer Abnahme der Nierenfunktion verbunden. Somit lässt sich zusammenfassen, dass nicht Typ-2-Diabetes sondern vielmehr die dabei auftretenden Nierenfunktionsstörungen zu einer Erhöhung der RBP4-Werte führen. Bei Lebererkrankten konnte ein Absinken der RBP4-Werte nachgewiesen werden, was der verminderten Bildung von RBP4 in der Leber bei diesen Patienten zuzuschreiben ist. Im zweiten Teil sollte der Frage nachgegangen werden, wie Retinol intrazellulär verstoffwechselt wird. Dabei lag der Fokus auf der Erforschung der bisher nicht bekannten Funktionen von CRBP-I im Fettgewebe und der Bauchspeicheldrüse. Zur Untersuchung der Funktionen von CRBP-I wurden Mäuse gezüchtet, bei denen das Gen für CRBP-I gelöscht wurde. Da CRBP-I für die Speicherung von Vitamin A in der Leber verantwortlich ist, zeigen diese Mäuse sehr geringe Vitamin-A-Speicher in der Leber. Das gleiche zeigte sich für die Bauchspeicheldrüse, die für die Sekretion von Insulin Vitamin A benötigt: In den Mäusen ohne CRBP-I waren die Retinol-Werte drastisch gesunken. Interessanterweise zeigte sich im Fettgewebe ein gegenteiliges Bild: Die Konzentrationen an Retinol und dessen Speicher waren in den Mäusen ohne CRBP-I höher im Vergleich zu den normalen Mäusen. Mit bestimmten Nachweismethoden konnte herausgefunden werden, dass Retinol im Fettgewebe an ein anderes RBP, das CRBP-III, gebunden wird und dadurch effektiver gespeichert werden kann als durch CRBP-I.
urn:nbn:de:kobv:517-opus-31428
3142
<hr/>
Parts of this thesis have been published in the following journals:<br/><br/>
1. Factors that influence retinol-binding protein 4 - transthyretin interaction are not altered in overweight type 2 diabetic subjects<br/>
Frey SK, Spranger J, Henze A, Pfeiffer AF, Schweigert FJ., Raila J. Metabolism
2009 Jan (accepted).<br/><br/>
2. Effect of renal replacement therapy on retinol-binding protein 4 isoforms<br/>
Frey SK, Nagl B, Henze A, Raila J, Tepel M, Schweigert FJ, Zidek W. Clin Chim
Acta. 2009 Mar;401(1-2):46-50.<br/><br/>
3. Evidence that kidney function but not type 2 diabetes mellitus determines
retinol-binding protein 4 (RBP4) serum levels.<br/>
Henze A, Frey SK, Raila J, Tepel M, Scholze A, Pfeiffer AF, Weickert MO,
Spranger J, Schweigert FJ. Diabetes. 2008 Dec;57(12):3323-6.<br/><br/>
4. Isoforms of retinol-binding protein 4 (RBP4) are increased in chronic diseases of the kidney but not of the liver.<br/>
Frey SK, Nagl B, Henze A, Raila J, Schlosser B, Berg T, Tepel M, Zidek W,
Weickert MO, Pfeiffer AF, Schweigert FJ. Lipids Health Dis. 2008 Aug
27;7(1):29.
WD 5900
WX 2500
WD 5275
Keine öffentliche Lizenz: Unter Urheberrechtsschutz
Simone K. Frey
deu
uncontrolled
Vitamin A
deu
uncontrolled
retinol
deu
uncontrolled
RBP
deu
uncontrolled
Retinol-Bindungsprotein 4
deu
uncontrolled
Diabetes
eng
uncontrolled
Vitamin A
eng
uncontrolled
retinol
eng
uncontrolled
RBP
eng
uncontrolled
Retinol-binding protein 4
eng
uncontrolled
diabetes
Naturwissenschaften und Mathematik
open_access
Institut für Ernährungswissenschaft
Universität Potsdam
Universität Potsdam
https://publishup.uni-potsdam.de/files/2973/frey_diss.pdf