Topic
Selenium
About: Selenium is a research topic. Over the lifetime, 21192 publications have been published within this topic receiving 429715 citations. The topic is also known as: Se & selen.
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161 citations
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TL;DR: The dietary selenium intakes of a young couple residing in Southern California were determined to be 107 and 99 micrograms/day for the husband and the wife, respectively, on the basis of a 30 day study, and glutathione peroxidase blood levels did not correlate with blood Se concentrations.
160 citations
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TL;DR: Selenium decreased the total number of colon tumors induced by MAM to 42 tumors as compared to a total of 73 tumors in rats receiving only MAM, while selenium at this level did not affect the weight gain of the animals.
160 citations
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TL;DR: Evidence is provided that both selenoproteins and low molecular weight selenocompounds are important for the cancer-protective effects of selenium, and that a lack ofselenoprotein activity increases colon cancer susceptibility.
Abstract: Selenium has cancer protective effects in a variety of experimental systems. Currently, it is not known whether selenoproteins or low molecular weight selenocompounds are responsible for this activity. To evaluate the contribution of selenoproteins to the cancer protective effects of selenium, we used transgenic mice that carry a mutant selenocysteine transfer RNA gene, which causes reduced selenoprotein synthesis. Selenium homeostasis was characterized in liver and colon of wild-type and transgenic mice fed selenium-deficient diets supplemented with 0, 0.1, or 2.0 microg selenium (as selenite)/g diet. (75)Se-labeling, Western blot analysis, and enzymatic activities revealed that transgenic mice have reduced (P < 0.05) liver and colon glutathione peroxidase expression, but conserved thioredoxin reductase expression compared with wild-type mice, regardless of selenium status. Transgenic mice had more (P < 0.05) selenium in the nonprotein fraction of the liver and colon than wild-type mice, indicating a greater amount of low molecular weight selenocompounds. Compared with wild-type mice, transgenic mice had more (P < 0.05) azoxymethane-induced aberrant crypt formation (a preneoplastic lesion for colon cancer). Supplemental selenium decreased (P < 0.05) the number of aberrant crypts and aberrant crypt foci in both wild-type and transgenic mice. These results provide evidence that a lack of selenoprotein activity increases colon cancer susceptibility. Furthermore, low molecular weight selenocompounds reduced preneoplastic lesions independent of the selenoprotein genotype. These results are, to our knowledge, the first to provide evidence that both selenoproteins and low molecular weight selenocompounds are important for the cancer-protective effects of selenium.
160 citations
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TL;DR: A review of microbial transformations of different forms of selenium in an environmental context, with special emphasis on bioremediation of Se pollution can be found in this article, where the authors discuss the potential of microbial methylation after reduction of Se oxyanions, if limitations with low reaction rates and capture of the volatile methylated Selenium species can be overcome.
Abstract: Selenium species, particularly the oxyanions selenite (SeO3 (2-)) and selenate (SeO4 (2-)), are significant pollutants in the environment that leach from rocks and are released by anthropogenic activities. Selenium is also an essential micronutrient for organisms across the tree of life, including microorganisms and human beings, particularly because of its presence in the 21st genetically encoded amino acid, selenocysteine. Environmental microorganisms are known to be capable of a range of transformations of selenium species, including reduction, methylation, oxidation, and demethylation. Assimilatory reduction of selenium species is necessary for the synthesis of selenoproteins. Dissimilatory reduction of selenate is known to support the anaerobic respiration of a number of microorganisms, and the dissimilatory reduction of soluble selenate and selenite to nanoparticulate elemental selenium greatly reduces the toxicity and bioavailability of selenium and has a major role in bioremediation and potentially in the production of selenium nanospheres for technological applications. Also, microbial methylation after reduction of Se oxyanions is another potentially effective detoxification process if limitations with low reaction rates and capture of the volatile methylated selenium species can be overcome. This review discusses microbial transformations of different forms of Se in an environmental context, with special emphasis on bioremediation of Se pollution.
160 citations