@article{MeyerMarkovaPohletal.2018, author = {Meyer, S{\"o}ren and Markova, Mariya and Pohl, Gabriele and Marschall, Talke Anu and Pivovarova, Olga and Pfeiffer, Andreas F. H. and Schwerdtle, Tanja}, title = {Development, validation and application of an ICP-MS/MS method to quantify minerals and (ultra-)trace elements in human serum}, series = {Journal of trace elements in medicine and biology}, volume = {49}, journal = {Journal of trace elements in medicine and biology}, publisher = {Elsevier GMBH}, address = {M{\"u}nchen}, issn = {0946-672X}, doi = {10.1016/j.jtemb.2018.05.012}, pages = {157 -- 163}, year = {2018}, abstract = {Multi-element determination in human samples is very challenging. Especially in human intervention studies sample volumes are often limited to a few microliters and due to the high number of samples a high-throughput is indispensable. Here, we present a state-of-the-art ICP-MS/MS-based method for the analysis of essential (trace) elements, namely Mg, Ca, Fe, Cu, Zn, Mo, Se and I, as well as food-relevant toxic elements such as As and Cd. The developed method was validated regarding linearity of the calibration curves, method LODs and LOQs, selectivity and trueness as well as precision. The established reliable method was applied to quantify the element serum concentrations of participants of a human intervention study (LeguAN). The participants received isocaloric diets, either rich in plant protein or in animal protein. While the serum concentrations of Mg and Mo increased in participants receiving the plant protein-based diet (above all legumes), the Se concentration in serum decreased. In contrast, the animal protein-based diet, rich in meat and dairy products, resulted in an increased Se concentration in serum.}, language = {en} } @phdthesis{Marschall2017, author = {Marschall, Talke Anu}, title = {Zytotoxizit{\"a}t, Bioverf{\"u}gbarkeit und Metabolismus kleiner Selenspezies in humanen Zellen und Entwicklung von ICP-QQQ-MS-basierten Methoden f{\"u}r deren Nachweis}, school = {Universit{\"a}t Potsdam}, pages = {115, VI}, year = {2017}, language = {de} } @article{MarschallBornhorstKuehneltetal.2016, author = {Marschall, Talke Anu and Bornhorst, Julia and Kuehnelt, Doris and Schwerdtle, Tanja}, title = {Differing cytotoxicity and bioavailability of selenite, methylselenocysteine, selenomethionine, selenosugar 1 and trimethylselenonium ion and their underlying metabolic transformations in human cells}, series = {Applied computing review : the publication of the ACM Special Interest Group on Applied Computing}, volume = {60}, journal = {Applied computing review : the publication of the ACM Special Interest Group on Applied Computing}, publisher = {Wiley-Blackwell}, address = {Hoboken}, issn = {1613-4125}, doi = {10.1002/mnfr.201600422}, pages = {2622 -- 2632}, year = {2016}, abstract = {Scope: The trace element selenium (Se) is an integral component of our diet. However, its metabolism and toxicity following elevated uptake are not fully understood. Since the either adverse or beneficial health effects strongly depend on the ingested Se species, five low molecular weight species were investigated regarding their toxicological effects, cellular bioavailability and species-specific metabolism in human cells. Methods and results: For the first time, the urinary metabolites methyl-2-acetamido-2-deoxy1- seleno-beta-D-galactopyranoside (selenosugar 1) and trimethylselenonium ion (TMSe) were toxicologically characterised in comparison to the food relevant species methylselenocysteine (MeSeCys), selenomethionine (SeMet) and selenite in human urothelial, astrocytoma and hepatoma cells. In all cell lines selenosugar 1 and TMSe showed no cytotoxicity. Selenite, MeSeCys and SeMet exerted substantial cytotoxicity, which was strongest in the urothelial cells. There was no correlation between the potencies of the respective toxic effects and the measured cellular Se concentrations. Se speciation indicated that metabolism of the respective species is likely to affect cellular toxicity. Conclusion: Despite being taken up, selenosugar 1 and TMSe are non-cytotoxic to urothelial cells, most likely because they are not metabolically activated. The absent cytotoxicity of selenosugar 1 and TMSe up to supra-physiological concentrations, support their importance as metabolites for Se detoxification.}, language = {en} } @article{MarschallKroepflJensenetal.2017, author = {Marschall, Talke Anu and Kroepfl, Nina and Jensen, Kenneth Bendix and Bornhorst, Julia and Meermann, B. and K{\"u}hnelt, Doris and Schwerdtle, Tanja}, title = {Tracing cytotoxic effects of small organic Se species in human liver cells back to total cellular Se and Se metabolites}, series = {Metallomics}, volume = {9}, journal = {Metallomics}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1756-5901}, doi = {10.1039/c6mt00300a}, pages = {268 -- 277}, year = {2017}, abstract = {Small selenium (Se) species play a major role in the metabolism, excretion and dietary supply of the essential trace element selenium. Human cells provide a valuable tool for investigating currently unresolved issues on the cellular mechanisms of Se toxicity and metabolism. In this study, we developed two isotope dilution inductively coupled plasma tandem-mass spectrometry based methods and applied them to human hepatoma cells (HepG2) in order to quantitatively elucidate total cellular Se concentrations and cellular Se species transformations in relation to the cytotoxic effects of four small organic Se species. Species-and incubation time-dependent results were obtained: the two major urinary excretion metabolites trimethylselenonium (TMSe) and methyl-2-acetamido-2-deoxy-1-seleno-beta- D-galactopyranoside (SeSugar 1) were taken up by the HepG2 cells in an unmodified manner and did not considerably contribute to the Se pool. In contrast, Se-methylselenocysteine (MeSeCys) and selenomethionine (SeMet) were taken up in higher amounts, they were largely incorporated by the cells (most likely into proteins) and metabolized to other small Se species. Two new metabolites of MeSeCys, namely gamma-glutamyl-Se-methylselenocysteine and Se-methylselenoglutathione, were identified by means of HPLC-electrospray-ionization-Orbitrap-MS. They are certainly involved in the (de-) toxification modes of Se metabolism and require further investigation.}, language = {en} } @article{RohnMarschallKroepfletal.2018, author = {Rohn, Isabelle and Marschall, Talke Anu and Kr{\"o}pfl, Nina and Jensen, Kenneth Bendix and Aschner, Michael and Tuck, Simon and Kuehnelt, Doris and Schwerdtle, Tanja and Bornhorst, Julia}, title = {Selenium species-dependent toxicity, bioavailability and metabolic transformations in Caenorhabditis elegans}, series = {Metallomics : integrated biometal science}, volume = {10}, journal = {Metallomics : integrated biometal science}, number = {6}, publisher = {Royal Society of Chemistry}, address = {Cambridge}, issn = {1756-5901}, doi = {10.1039/c8mt00066b}, pages = {818 -- 827}, year = {2018}, abstract = {The essential micronutrient selenium (Se) is required for various systemic functions, but its beneficial range is narrow and overexposure may result in adverse health effects. Additionally, the chemical form of the ingested selenium contributes crucially to its health effects. While small Se species play a major role in Se metabolism, their toxicological effects, bioavailability and metabolic transformations following elevated uptake are poorly understood. Utilizing the tractable invertebrate Caenorhabditis elegans allowed for an alternative approach to study species-specific characteristics of organic and inorganic Se forms in vivo, revealing remarkable species-dependent differences in the toxicity and bioavailability of selenite, selenomethionine (SeMet) and Se-methylselenocysteine (MeSeCys). An inverse relationship was found between toxicity and bioavailability of the Se species, with the organic species displaying a higher bioavailability than the inorganic form, yet being less toxic. Quantitative Se speciation analysis with HPLC/mass spectrometry revealed a partial metabolism of SeMet and MeSeCys. In SeMet exposed worms, identified metabolites were Se-adenosylselenomethionine (AdoSeMet) and Se-adenosylselenohomocysteine (AdoSeHcy), while worms exposed to MeSeCys produced Se-methylselenoglutathione (MeSeGSH) and -glutamyl-MeSeCys (-Glu-MeSeCys). Moreover, the possible role of the sole selenoprotein in the nematode, thioredoxin reductase-1 (TrxR-1), was studied comparing wildtype and trxr-1 deletion mutants. Although a lower basal Se level was detected in trxr-1 mutants, Se toxicity and bioavailability following acute exposure was indistinguishable from wildtype worms. Altogether, the current study demonstrates the suitability of C. elegans as a model for Se species dependent toxicity and metabolism, while further research is needed to elucidate TrxR-1 function in the nematode.}, language = {en} }