R F Burk

..It can be predicted that more proteins will be discovered that take advantage of the chemical properties of selenium...

..These forms of the element appear to be metabolized by specific selenium metabolic processes...

..Since most estimates of selenium intake in the United States are 80 micrograms per day or greater, routine selenium supplementation is not recommended in the United States...

..The heparin-binding properties of selenoprotein P could be the basis for its binding to tissue. Its localization to the vicinity of endothelial cells is potentially relevant to its oxidant defense function...

..These results indicate that thioredoxin reductase activity in liver and kidney is sensitive to selenium nutritional status but that brain thioredoxin reductase activity is less sensitive...

..These results show that the thioredoxin system can reduce dehydroascorbate, and that this function is required for maintenance of liver ascorbate content...

..Selenoprotein P secretion was inhibited by dithiothreitol, suggesting that disulfide bond formation is necessary for secretion of the mature protein...

..Because only two stem-loop structures are present in the 3' untranslated region of selenoprotein P mRNA, it can be concluded that a separate stem-loop structure is not required for each selenocysteine residue...

..These results suggest that thioredoxin reductase can function as a cytosolic ascorbyl free radical reductase that may complement cellular ascorbate recycling by membrane-bound NADH-dependent reductases...

..These studies indicate that GSH promotes F2-IsoP formation and diminishes D2/E2-IsoP levels in vitro and in vivo by causing reduction of IsoP endoperoxides...

..These results show that mitochondria can recycle ascorbate, which in turn might help to prevent deleterious effects of oxidant stress in the organelle...

..This nutritional myopathy is much more severe than the myopathy that occurs with vitamin E deficiency alone...

..We postulate that selenoprotein P protects the centrilobular endothelial cells against injury by oxidant molecules that result from diquat administration...

..More research will be required to test this hypothesis and to establish the biochemical function of selenoprotein P...

..0, explains the release of selenoprotein P from heparin binding as pH rises above 7.0. It can be speculated that this property would lead to increased binding of selenoprotein P in tissue regions that have low pH...

..Whereas TR contributes little to ascorbate recycling in H4IIE cells, selenium spares ascorbate in culture and alpha-tocopherol in response to an oxidant stress...

..one-third of the selenium from plasma or 0.4 mumol Se/l at a total selenium concentration of 1.1 mumol/l, indicating that selenoprotein P constituted this proportion of total plasma selenium in healthy US blood donors...

..The primary structure of selenoprotein P suggests that it might be responsible for some of the antioxidant properties of selenium...

..Plasma selenium seems to reflect the selenomethionine content of yeast but not the other yeast selenium forms. As judged by urinary selenium excretion, selenium in the form of selenomethionine is better absorbed than selenite...

..These results indicate that the paralysis and death caused by combined deficiency of vitamins E and C in guinea pigs is caused by severe damage in the brainstem and spinal cord...

..Selenium status in premenopausal breast cancer patients, as measured by serum selenium, GPx and SelP, was within the normal range before and following adjuvant chemotherapy, and was not affected by chemotherapy-induced ovarian failure...

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..The results of this study demonstrate that the C terminus of Sepp1 is critical for the maintenance of selenium in brain and testis but not for the maintenance of whole body selenium...

..These results suggest that Sepp1 is more important for maintaining selenium in the hippocampus than in other brain regions. They also confirm the position of the brain at the apex of the organ selenium hierarchy...

..Co-immunoprecipitation analysis demonstrated an interaction of testis ApoER2 with Sepp1. These data demonstrate that Sertoli cell ApoER2 is a Sepp1 receptor and a component of the selenium delivery pathway to spermatogenic cells...

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..Further, they link HO-1 induction with a rise in serum iron, suggesting that the iron resulting from catabolism of heme by HO-1 is released by the liver...

..Those areas have high metabolic rates. We conclude that interference with Sepp1 function damages auditory and motor areas, at least in part by restricting selenium supply to the brain regions...

..These results demonstrate that kidney selenium homeostasis is mediated by a megalin-dependent Sepp1 uptake pathway in the proximal tubule...

..We conclude that Se deficiency causes cytosolic oxidative stress but that vitamin E deficiency does not. This suggests that the oxidant defense mechanisms in which these antioxidant nutrients function are independent of one another...

..These data validate M2-associated molecules as functioning in reducing the impact of parasite infection on the host...

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..Selenium as selenomethionine had nearly twice the bioavailability of selenium as selenite...

..Thioredoxin reductase also decreased F(2)-isoprostanes in ghosts oxidized by ferricyanide, suggesting that its ability to spare alpha-tocopherol relates to reduction of lipid hydroperoxides...

..Further, they indicate that transport forms of selenium other than Se-P exist because selenium levels of all tissues except testis responded to increases of dietary selenium in Sepp(-/-) mice...

..In the rat hepatoma cell line H4IIE, inhibition of TrxR by aurothioglucose or by 1-chloro-2,4-dinitrobenzene led to induction of HO-1. We conclude that loss of TrxR is responsible for the induction of HO-1 by selenium deficiency...

..Thus, there is evidence for both antioxidant and selenium transport functions of selenoprotein P...

..We speculate that selenium deficiency affects hepatic antioxidant selenoproteins, resulting in an up-regulation of HO-1...

..The loss of selenium from selenoproteins is probably through the mechanism of oxidation of selenocysteine residue to selenoxide followed by syn-beta-elimination of selenenic acid during sample processing...

..This syndrome indicates that these antioxidant vitamins are related in vivo. We speculate that acute oxidative injury in the central nervous system underlies the clinical syndrome...

..The disulfide formed by Cys153-Cys156 also has some characteristics of a redox active pair...

..Both the absence of selenoprotein P and a low dietary selenium supply are necessary for the dysfunction to occur, indicating that selenoprotein P and at least one other form of selenium supply the element to the brain...

..These data suggest that the known loss of male fertility in selenium deficiency results from the sequential development of sperm defects expressed during both spermiogenesis and maturation in the epididymis...

..It is concluded that selenoprotein P contains these two selenenylsulfide bonds...

..These data demonstrate that SEPP1 is required for development of functional spermatozoa and indicate that it is an essential component of the selenium delivery pathway for developing germ cells...

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..This pilot study aimed to determine and compare selenium status in two Colombian populations with different gastric cancer risks: a high-risk area in the volcanic region of the Andes Mountains and a low-risk area on the Pacific coast...