TY - JOUR A1 - Maares, Maria A1 - Keil, Claudia A1 - Koza, Jenny A1 - Straubing, Sophia A1 - Schwerdtle, Tanja A1 - Haase, Hajo T1 - In Vitro Studies on Zinc Binding and Buffering by Intestinal Mucins JF - International Journal of Molecular Sciences N2 - The investigation of luminal factors influencing zinc availability and accessibility in the intestine is of great interest when analyzing parameters regulating intestinal zinc resorption. Of note, intestinal mucins were suggested to play a beneficial role in the luminal availability of zinc. Their exact zinc binding properties, however, remain unknown and the impact of these glycoproteins on human intestinal zinc resorption has not been investigated in detail. Thus, the aim of this study is to elucidate the impact of intestinal mucins on luminal uptake of zinc into enterocytes and its transfer into the blood. In the present study, in vitro zinc binding properties of mucins were analyzed using commercially available porcine mucins and secreted mucins of the goblet cell line HT-29-MTX. The molecular zinc binding capacity and average zinc binding affinity of these glycoproteins demonstrates that mucins contain multiple zinc-binding sites with biologically relevant affinity within one mucin molecule. Zinc uptake into the enterocyte cell line Caco-2 was impaired by zinc-depleted mucins. Yet this does not represent their form in the intestinal lumen in vivo under zinc adequate conditions. In fact, zinc-uptake studies into enterocytes in the presence of mucins with differing degree of zinc saturation revealed zinc buffering by these glycoproteins, indicating that mucin-bound zinc is still available for the cells. Finally, the impact of mucins on zinc resorption using three-dimensional cultures was studied comparing the zinc transfer of a Caco-2/HT-29-MTX co-culture and conventional Caco-2 monoculture. Here, the mucin secreting co-cultures yielded higher fractional zinc resorption and elevated zinc transport rates, suggesting that intestinal mucins facilitate the zinc uptake into enterocytes and act as a zinc delivery system for the intestinal epithelium. KW - intestinal zinc resorption KW - zinc binding KW - mucus layer KW - intestinal mucins KW - in vitro intestinal model KW - goblet cells KW - Caco-2/HT-29-MTX-model Y1 - 2018 U6 - https://doi.org/10.3390/ijms19092662 SN - 1422-0067 VL - 19 IS - 9 ER - TY - GEN A1 - Maares, Maria A1 - Keil, Claudia A1 - Koza, Jenny A1 - Straubing, Sophia A1 - Schwerdtle, Tanja A1 - Haase, Hajo T1 - In Vitro Studies on Zinc Binding and Buffering by Intestinal Mucins T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - The investigation of luminal factors influencing zinc availability and accessibility in the intestine is of great interest when analyzing parameters regulating intestinal zinc resorption. Of note, intestinal mucins were suggested to play a beneficial role in the luminal availability of zinc. Their exact zinc binding properties, however, remain unknown and the impact of these glycoproteins on human intestinal zinc resorption has not been investigated in detail. Thus, the aim of this study is to elucidate the impact of intestinal mucins on luminal uptake of zinc into enterocytes and its transfer into the blood. In the present study, in vitro zinc binding properties of mucins were analyzed using commercially available porcine mucins and secreted mucins of the goblet cell line HT-29-MTX. The molecular zinc binding capacity and average zinc binding affinity of these glycoproteins demonstrates that mucins contain multiple zinc-binding sites with biologically relevant affinity within one mucin molecule. Zinc uptake into the enterocyte cell line Caco-2 was impaired by zinc-depleted mucins. Yet this does not represent their form in the intestinal lumen in vivo under zinc adequate conditions. In fact, zinc-uptake studies into enterocytes in the presence of mucins with differing degree of zinc saturation revealed zinc buffering by these glycoproteins, indicating that mucin-bound zinc is still available for the cells. Finally, the impact of mucins on zinc resorption using three-dimensional cultures was studied comparing the zinc transfer of a Caco-2/HT-29-MTX co-culture and conventional Caco-2 monoculture. Here, the mucin secreting co-cultures yielded higher fractional zinc resorption and elevated zinc transport rates, suggesting that intestinal mucins facilitate the zinc uptake into enterocytes and act as a zinc delivery system for the intestinal epithelium. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 1079 KW - intestinal zinc resorption KW - zinc binding KW - mucus layer KW - intestinal mucins KW - in vitro intestinal model KW - goblet cells KW - Caco-2/HT-29-MTX-model Y1 - 2021 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-469078 SN - 1866-8372 IS - 1079 ER - TY - JOUR A1 - Maares, Maria A1 - Duman, Ayse A1 - Keil, Claudia A1 - Schwerdtle, Tanja A1 - Haase, Hajo T1 - The impact of apical and basolateral albumin on intestinal zinc resorption in the Caco-2/HT-29-MTX co-culture model JF - Metallomics : integrated biometal science N2 - The molecular mechanisms of intestinal zinc resorption and its regulation are still topics of ongoing research. To this end, the application of suitable in vitro intestinal models, optimized with regard to their cellular composition and medium constituents, is of crucial importance. As one vital aspect, the impact of cell culture media or buffer compounds, respectively, on the speciation and cellular availability of zinc has to be considered when investigating zinc resorption. Thus, the present study aims to investigate the impact of serum, and in particular its main constituent serum albumin, on zinc uptake and toxicity in the intestinal cell line Caco-2. Furthermore, the impact of serum albumin on zinc resorption is analyzed using a co-culture of Caco-2 cells and the mucin-producing goblet cell line HT-29-MTX. Apically added albumin significantly impaired zinc uptake into enterocytes and buffered its cytotoxicity. Yet, undigested albumin does not occur in the intestinal lumen in vivo and impairment of zinc uptake was abrogated by digestion of albumin. Interestingly, zinc uptake, as well as gene expression studies of mt1a and selected intestinal zinc transporters after zinc incubation for 24 h, did not show significant differences between 0 and 10% serum. Importantly, the basolateral application of serum in a transport study significantly enhanced fractional apical zinc resorption, suggesting that the occurrence of a zinc acceptor in the plasma considerably affects intestinal zinc resorption. This study demonstrates that the apical and basolateral medium composition is crucial when investigating zinc, particularly its intestinal resorption, using in vitro cell culture. Y1 - 2018 U6 - https://doi.org/10.1039/c8mt00064f SN - 1756-5901 SN - 1756-591X VL - 10 IS - 7 SP - 979 EP - 991 PB - Royal Society of Chemistry CY - Cambridge ER - TY - GEN A1 - Zeiher, Johannes A1 - Duch, M. A1 - Kroll, Lars Eric A1 - Mensink, Gerhardus Bernardus Maria A1 - Finger, Jonas David A1 - Keil, Thomas T1 - Domain-specific physical activity patterns and cardiorespiratory fitness among adults in Germany T2 - The European Journal of Public Health N2 - Background Studies show that occupational physical activity (OPA) has less health-enhancing effects than leisure-time physical activity (LTPA). The spare data available suggests that OPA rarely includes aerobic PAs with little or no enhancing effects on cardiorespiratory fitness (CRF) as a possible explanation. This study aims to investigate the associations between patterns of OPA and LTPA and CRF among adults in Germany. Methods 1,204 men and 1,303 women (18-64 years), who participated in the German Health Interview and Examination Survey 2008-2011, completed a standardized sub-maximal cycle ergometer test to estimate maximal oxygen consumption (VO2max). Job positions were coded according to the level of physical effort to construct an occupational PA index and categorized as low vs. high OPA. LTPA was assessed via questionnaires and dichotomized in no vs. any LTPA participation. A combined LTPA/OPA variable was used (high OPA/ LTPA, low OPA/LTPA, high OPA/no LTPA, low OPA/no LTPA). Information on potential confounders was obtained via questionnaires (e.g., smoking and education) or physical measurements (e.g., waist circumference). Multi-variable logistic regression was used to analyze associations between OPA/LTPA patterns and VO2max. Results Preliminary analyses showed that less-active men were more likely to have a low VO2max with odds ratios (ORs) of 0.80 for low OPA/LTPA, 1.84 for high OPA/no LTPA and 3.46 for low OPA/no LTPA compared to high OPA/LTPA. The corresponding ORs for women were 1.11 for low OPA/LTPA, 3.99 for high OPA/no LTPA and 2.44 for low OPA/no LTPA, indicating the highest likelihood of low fitness for women working in physically demanding jobs and not engaging in LTPA. Conclusions Findings confirm a strong association between LTPA and CRF and suggest an interaction between OPA and LTPA patterns on CRF within the workforce in Germany. Women without LTPA are at high risk of having a low CRF, especially if they work in physically demanding jobs. Key messages Women not practicing leisure-time physical activity are at risk of having a low cardiorespiratory fitness, especially if they work in physically demanding jobs. Different impact of domains of physical activity should be considered when planning interventions to enhance fitness among the adult population. Y1 - 2019 SN - 1101-1262 SN - 1464-360X VL - 29 IS - Supplement. 4 PB - Oxford Univ. Press CY - Oxford ER - TY - JOUR A1 - Schmitz, Andreas A1 - Schmidt-Wellenburg, Christian A1 - Witte, Daniel A1 - Keil, Maria T1 - In welcher Gesellschaft forschen wir eigentlich? BT - Struktur und Dynamik des Feldes der deutschen Soziologie JF - Zeitschrift für theoretische Soziologie Y1 - 2020 U6 - https://doi.org/10.3262/ZTS1902245 SN - 2195-0695 SN - 2751-4552 VL - 8 IS - 2 SP - 245 EP - 281 PB - Beltz Juventa CY - Weinheim ER -