Disease relevance of selenium

• CONCLUSIONS: Selenium treatment did not protect against development of basal or squamous cell carcinomas of the skin [1].
• CONCLUSIONS: Selenium may have a protective role against the development of ovarian cancer [2].
• The susceptibility of the tobacco cells to selenate toxicity was high under conditions of sulfur nutrition that derepress ATP sulfurylase, and low under conditions that repress ATP sulfurylase, in agreement with the idea that selenate acts via a functional sulfate assimilation pathway [3].
• Selenophosphate synthetase, the Escherichia coli selD gene product, is a 37-kDa protein that catalyzes the synthesis of selenophosphate from ATP and selenide [4].
• An enzyme preparation from Salmonella typhimurium catalyzes the conversion of 5-methylaminomethyl-2-thiouridine in tRNAs to 5-methylaminomethyl-2-selenouridine when supplemented with selenide and ATP [5].

Psychiatry related information on selenium

• On the basis of inductively coupled plasma/mass spectroscopic analyses, corroborated by operant behaviour and locomotor activity investigations, an orally-active phenylaminoalkyl selenide with restricted CNS permeability was successfully developed [6].
• 1. Selenium status was investigated in patients with chronic renal failure, with special regard to its relations to the dialysis treatments, dietary habits and clinical signs of atherosclerosis [7].
• To determine the uptake capacity and long-term stability, hydrocalumite solid solutions between chromate/selenate and hydroxyl were synthesized over a reaction time of more than one year [8].

High impact information on selenium

• This Account focuses on recent developments of the chemistry of metal thio- and selenocarboxylates in our laboratory and potential use of some of these compounds as single-source precursors for making metal sulfide and selenide bulk materials, thin films, and nanoparticles [9].
• A labile selenium donor compound monoselenophosphate is synthesized from selenide and ATP by selenophosphate synthetase (SPS) [10].
• E-Se rhodanese was stable in the presence of excess GSH at neutral pH at 37 degrees C. E-Se rhodanese could effectively replace the high concentrations of selenide normally used in the selenophosphate synthetase in vitro assay in which the selenium-dependent hydrolysis of ATP is measured [11].
• The dependence of reaction velocity on ATP concentration shows sigmoidal kinetics, whereas dependence on selenide concentration obeys Michaelis-Menten kinetics indicating a Km value of 46 microM for selenide [5].
• We have reconstituted apo-aconitase with iron and selenide to obtain Fe4Se4 aconitase [12].

Chemical compound and disease context of selenium

• Extracellular Production of Hydrogen Selenide Accounts for Thiol-assisted Toxicity of Selenite against Saccharomyces cerevisiae [13].
• Letter: Selenium protection against mercury toxicity. Binding of methylmercury by the selenohydryl-containing ligand [14].
• Since selenate induced a moderate decrease in body weight due to an anorexigenic effect, we checked that there was no improvement of glucose homeostasis or hepatic glucose metabolism in an additional group of calorie-restricted diabetic rats, which was weight-matched with the selenate group [15].
• PURPOSE: We determined the effects of selenomethionine, the major organic selenium containing compound found in the diet and the form of selenium being used in the Selenium and Vitamin E Cancer Prevention Trial, on prostate cancer cells [16].
• Diallyl selenide was at least 300-fold more effective than diallyl sulfide in protecting against 7,12-dimethylbenz[a]anthracene (DMBA)-induced mammary adenocarcinomas in rats [17].

Biological context of selenium

• These results show that selenite and selenate use different mechanisms to inhibit cell growth [18].
• Our earlier work indicated that distinct cell death pathways are likely involved in apoptosis induced by the CH3SeH and the hydrogen selenide pools of selenium metabolites [19].
• In the presence of insulin, selenate enhances insulin receptor kinase activity and phosphorylations of insulin-stimulated tyrosyl phosphoproteins [20].
• In conclusion, selenate induces a sustained improvement of glucose homeostasis in streptozotocin-diabetic rats by an insulin-like action, which involves partial correction of altered pretranslational regulatory mechanisms in liver metabolism [15].
• In the latter, however, an amino acid replacement is present within the catalytic domain and lacks selenide-dependent SPS activity [21].

Anatomical context of selenium

• The insulin-like effects of selenate in rat adipocytes [20].
• The reduction of selenate to selenite is catalyzed by a selenate reductase, previously shown to be located in the periplasmic space of the cell [22].
• These results indicate that selenate added to soy formula is highly available and effective at maintaining infant plasma and erythrocyte selenium concentrations and GPx activities that are greater than those of infants fed soy formula not fortified with selenium [23].
• RESULTS: Selenium supplementation increased plasma selenium concentrations, the body exchangeable selenium pool (measured by using (74)Se), and lymphocyte phospholipid and cytosolic glutathione peroxidase activities [24].
• Zinc, vanadate and selenate inhibit the tri-iodothyronine-induced expression of fatty acid synthase and malic enzyme in chick-embryo hepatocytes in culture [25].

Associations of selenium with other chemical compounds

• The cysteine mutant enzyme exhibited selenophosphate synthetase activity in the assay that measures selenide-dependent AMP formation from ATP [26].
• However, previous examinations could link a defect in sulfate uptake of S. cerevisiae to an increased resistance against toxic substances like selenate and chromate in the environment, which share the same permeases (5-7) [27].
• No differences in molecular weight, [3H]glucosamine/[35S]sulfuric acid ratios, or disaccharide composition were observed when the heparan sulfate synthesized by selenate-treated cells was compared with that of control cells [28].
• Selenium uptake by S. cerevisiae is considerably enhanced in the presence of external thiols, most likely through internalization of hydrogen selenide [13].
• Furthermore, in intact cells addition of 1 mM selenate stimulated tyrosyl phosphorylation of 210-, 170-, 120-, 95-, 70-, and 60-kDa proteins but failed to stimulate insulin receptor kinase activity, suggesting that selenate stimulated other tyrosine kinase [20].

Gene context of selenium

• SelD homolog from Drosophila lacking selenide-dependent monoselenophosphate synthetase activity [29].
• Antisense plants of Sultr1;1 showed reduced accumulation of sulfate in roots, particularly in plants treated with selenate, suggesting that the inducible transporter Sultr1;1 contributes to the uptake of sulfate under stressed conditions [30].
• CONCLUSIONS: Selenium-induced changes in MMP-2/TIMP-1 secretion may alter the balance of extracellular matrix turnover in the conventional outflow pathway and cause an increase in intraocular pressure that eventually leads to glaucoma [31].
• Furthermore, selenide formed by TR-mediated reduction of selenite and GS-Se-SG inhibits lipoxygenase and changes the electron spin resonance spectrum of the active site iron [32].
• Selenate is reduced by Grx and Trx in the presence of GSH [32].

Analytical, diagnostic and therapeutic context of selenium

• A titration of methemerythrin with selenide indicates that this derivative forms by a two step process consisting of first, reduction to the semi-met oxidation level by selenide and second, binding of selenide to either one or both irons [33].
• Selenium compounds have a long history in chemoprevention of mammary and colon cancers in rodent models [34].
• Selenium compounds are in current clinical trials, having shown promise in prevention of prostate and other human cancers [34].
• Sequence analysis of the ddh gene cluster showed that the ddhA gene encodes a polypeptide with highest sequence similarity to the molybdopterin-containing subunits of selenate reductase, ethylbenzene dehydrogenase [35].
• The purpose of this study was to determine whether selenate fortification of infant formula would improve the selenium status of relatively well, growing, preterm infants during the first 12 wk of enteral feeding [36].

References