Person: Höra, Christian
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1987
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Höra
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Christian
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Veröffentlichung Effects of Zinc Oxide Nanoparticles on model systems of the intestinal barrier(2022) Mittag, Anna; Höra, Christian; Owesny, Patricia; Kämpfe, Alexander DavidZinc oxide nanoparticles (ZnO NP) are often used in the food sector, among others, because of their advantageous properties. As part of the human food chain, they are inevitably taken up orally. The debate on the toxicity of orally ingested ZnO NP continues due to incomplete data. Therefore, the aim of our study was to examine the effects of two differently sized ZnO NP (<50 nm and <100 nm primary particle size; 123â€Ì614 mikromol/L) on two model systems of the intestinal barrier. Differentiated Caco-2 enterocytes were grown on Transwell inserts in monoculture and also in coculture with the mucus-producing goblet cell line HT29-MTX. Although no comprehensive mucus layer was detectable in the coculture, cellular zinc uptake was clearly lower after a 24-h treatment with ZnO NP than in monocultured cells. ZnO NP showed no influence on the permeability, metabolic activity, cytoskeleton and cell nuclei. The transepithelial electrical resistance was significantly increased in the coculture model after treatment with _307 _mol/L ZnO NP. Only small zinc amounts (0.07â€Ì0.65 mikrog/mL) reached the basolateral area. Our results reveal that the cells of an intact intestinal barrier interact with ZnO NP but do not suffer serious damage. Quelle: ArtikelVeröffentlichung Lead, cadmium, mercury, and chromium in urine and blood of children and adolescents in Germany - Human biomonitoring results of the German Environmental Survey 2014-2017 (GerES V)(2021) Doyle, Ulrike; Höra, Christian; Kämpfe, Alexander David; Kolossa-Gehring, Marike; Murawski, Aline; Rucic, Enrico; Schmied-Tobies, Maria Irene Hilde; Vogel, NinaMetals reach humans through food and drinking water intake and inhalation of airborne particles and can have detrimental health effects in particular for children. The metals presented here (lead, cadmium, chromium, and mercury) could lead to toxic effects such as neurotoxicity, mutagenicity, and have been classified as (possible) carcinogens. Using population representative data from the German Environmental Survey 2014-2017 (GerES V) from 3- to 17-year-old children on lead and cadmium in blood (n = 720) and on cadmium, chromium, and mercury in urine (n = 2250) we describe current internal exposure levels, and socio-demographic and substance-specific exposure determinants. Average internal exposure (geometric means) in blood was 9.47 (micro)g/L for lead and below 0.06 (micro)g/L (limit of quantification) for cadmium, and in urine 0.072 (micro)g/L for cadmium, 0.067 (micro)g/L for mercury, and 0.393 (micro)g/L for chromium, respectively. Younger children have higher concentrations of lead and chromium compared to 14-17-year-old adolescents, and boys have slightly higher mercury concentrations than girls. With respect to substance specific determinants, higher lead concentrations emerged in participants with domestic fuel and in non-smoking children with smokers in the household, higher levels of cadmium were associated with smoking and vegetarian diet and higher levels of mercury with the consumption of seafood and amalgam teeth fillings. No specific exposure determinants emerged for chromium. The health based guidance value HBM-I was not exceeded for mercury and for cadmium in urine it was exceeded by 0.6% of the study population. None of the exceedances was related to substantial tobacco smoke exposure. Comparisons to previous GerES cycles (GerES II, 1990-1992; GerES IV, 2003-2006) indicate continuously lower levels. © 2021 Elsevier GmbHVeröffentlichung A chip-integrated optical microfluidic pressure sensor(2017) Kiontke, Andreas; Höra, Christian; Pahl, Maik; Belder, DetlevPressure sensing inside microfluidic channels in glass chips was achieved by integrating an oxygen sensitive luminescent sensor layer inside of an air-filled cavity. The device enables reliable determination of gas pressures, as well as flow rate-induced liquid backpressures at various positions along a channel. This optically readable microfluidic pressure sensor allows on-chip pressure sensing with high sensitivity at up to 9 mbar, and unsurpassed working range from atmospheric pressure up to 5 bar. Investigation of the system revealed high flexibility, stability and reproducibility of the proposed method. In addition to the pressure determination, the integrated luminescent sensor allows simultaneous detection of the temperature and oxygen content of a process medium. Quelle: http://www.sciencedirect.com/Veröffentlichung The role of dietary factors on blood lead concentration in children and adolescents - Results from the nationally representative German Environmental Survey 2014-2017 (GerES V)(2022) Hahn, Domenica; Höra, Christian; Kämpfe, Alexander David; Kolossa-Gehring, Marike; Schmied-Tobies, Maria Irene Hilde; Vogel, NinaIn industrialized nations, human lead exposure has decreased significantly in recent decades. Nevertheless, due to its toxic effects, this heavy metal remains a public health concern with children and adolescents being particularly at risk. In Europe nowadays, oral intake via food and drinking water is the predominant exposure pathway for lead. The objective of the present study was to investigate the association between dietary factors and blood lead (PbB) level of 3- to 17-year-old children and adolescents living in Germany, using data from the fifth German Environmental Health Survey (GerES V) and the Child and Adolescent Health Survey (KiGGS Wave 2). GerES V and KiGGS Wave 2 are two national population-representative studies conducted between 2014 and 2017, including measurement of lead concentrations in blood from 720 children and adolescents aged 3-17 years (mean age = 10.21, SD age = 4.36). Using multiple linear regression, sociodemographic and environmental characteristics as well as dietary factors could be identified as significant exposure determinants of PbB concentrations. Lead intake via domestic tap water was the strongest predictor of elevated PbB levels with 27.6% (p-value< .001) higher concentrations of highest compared to none lead intake via tap water. Other foods which were found to be relevant to PbB levels were meat, fruit, and fruit juice. While meat or fruit consumption were each associated with about 13% (p-value < .05) lower PbB levels, fruit juice drinking was associated with up to 12.2% (p-value = .04) higher PbB levels. In conclusion, results indicate the importance of dietary habits for lead exposure in children and adolescents. To protect vulnerable groups, it is recommended that future research and lead-reducing measures pay more attention to dietary links. © 2022 The Authors.Veröffentlichung A chip-integrated highly variable thermal flow rate sensor(2016) Höra, Christian; Skadell, Mirjam M.; Pfeiffer, Simon A.In this work, we present an approach for seamless integration of a highly variable flow rate sensor in chip based microfluidic devices. This novel, optically readable microfluidic calorimetric flow rate sensor is realized by a combination of an inkjet printed heating element with a fluorescent sensor layer inside microfluidic channels. This enables to read out flow rate induced variances in the temperature profile along the channels, which results in an unsurpassed wide working range of the microfluidic anemometer from the lower nl min-1 range up to several 100 Nano-l min-1. The system was thoroughly investigated and revealed high flexibility, stability, repeatability and sensitivity. Quelle: http://www.sciencedirect.comVeröffentlichung Cellular uptake and toxicological effects of differently sized zinc oxide nanoparticles in intestinal cells(2021) Mittag, Anna; Höra, Christian; Kämpfe, Alexander David; Kuckelkorn, JochenDue to their beneficial properties, the use of zinc oxide nanoparticles (ZnO NP) is constantly increasing, especially in consumer-related areas, such as food packaging and food additives, which is leading to an increased oral uptake of ZnO NP. Consequently, the aim of our study was to investigate the cellular uptake of two differently sized ZnO NP (<50 nm and <100 nm; 12-1229 (micro)mol/L) using two human intestinal cell lines (Caco-2 and LT97) and to examine the possible resulting toxic effects. ZnO NP (<50 nm and <100 nm) were internalized by both cell lines and led to intracellular changes. Both ZnO NP caused time- and dose-dependent cytotoxic effects, especially at concentrations of 614 (micro)mol/L and 1229 (micro)mol/L, which was associated with an increased rate of apoptotic and dead cells. ZnO NP < 100 nm altered the cell cycle of LT97 cells but not that of Caco-2 cells. ZnO NP < 50 nm led to the formation of micronuclei in LT97 cells. The Ames test revealed no mutagenicity for both ZnO NP. Our results indicate the potential toxicity of ZnO NP after oral exposure, which should be considered before application. © 2021 by the authorsVeröffentlichung Impact of in vitro digested zinc oxide nanoparticles on intestinal model systems(2022) Mittag, Anna; Höra, Christian; Singer, Alina; Kämpfe, Alexander DavidBackground: Zinc oxide nanoparticles (ZnO NP) offer beneficial properties for many applications, especially in the food sector. Consequently, as part of the human food chain, they are taken up orally. The toxicological evaluation of orally ingested ZnO NP is still controversial. In addition, their physicochemical properties can change during digestion, which leads to an altered biological behaviour. Therefore, the aim of our study was to investigate the fate of two different sized ZnO NP (< 50 nm and < 100 nm) during in vitro digestion and their effects on model systems of the intestinal barrier. Differentiated Caco-2 cells were used in mono- and coculture with mucus-producing HT29-MTX cells. The cellular uptake, the impact on the monolayer barrier integrity and cytotoxic effects were investigated after 24 h exposure to 123-614 mikroM ZnO NP. Results: In vitro digested ZnO NP went through a morphological and chemical transformation with about 70% free zinc ions after the intestinal phase. The cellular zinc content increased dose-dependently up to threefold in the monoculture and fourfold in the coculture after treatment with digested ZnO NP. This led to reactive oxygen species but showed no impact on cellular organelles, the metabolic activity, and the mitochondrial membrane potential. Only very small amounts of zinc (< 0.7%) reached the basolateral area, which is due to the unmodified transepithelial electrical resistance, permeability, and cytoskeletal morphology. Conclusions: Our results reveal that digested and, therefore, modified ZnO NP interact with cells of an intact intestinal barrier. But this is not associated with serious cell damage. Quelle: Artikel