(n.) A binary compound of selenium, or a compound regarded as binary; as, ethyl selenide.
Example Sentences:
(1) From this work it can be concluded that diallyl selenides are readily cleaved by mild oxidation, whereas dialkyl selenides and benzyl alkyl selenides can only be cleaved when the alkyl part of the selenide has an electron-withdrawing group next to the beta-carbon from selenium.
(2) This assay employed high pressure liquid chromatography separation and quantitation of the trimethylselenonium ion produced by thioether methyltransferase acting on S-adenosylmethionine and dimethyl selenide.
(3) The results support the hypothesis that H2Se or a similarly reduced selenide is the product of selenite metabolism by rat erythrocytes.
(4) It was concluded that Fraction C contains a methyltransferase acting on small amounts of hydrogen selenide produced non-enzymically by the reaction of selenite with GSH, and that stimulation by Fraction A results partly from the NADPH-linked formation of hydrogen selenide catalyzed by glutathione reductase present in Fraction A.
(5) 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.
(6) Both appear to inhibit Se volatilization by reacting with the selenide product(s).
(7) The selenium found in the liver subcellular organelle fractions was present in at least three oxidation states: acid-volatile selenium, assumed to be selenide, zinc-hydrochloric acid-reducible selenium, assumed to be selenite, and higher oxidation states of selenium and organic derivatives, called selenate for convenience.
(8) Investigation by energy-dispersive analysis of X-rays (EDAX) indicated the precipitation of silver as selenide.
(9) Considering the effects of diet on the various enzymes known from our previous studies to be involved in dimethyl selenide synthesis, it was concluded that the enhanced ability of rats fed stock diet to synthesize dimethyl selenide results from the induction of a liver microsomal enzyme, apparently a Se-methyltransferase, caused by unknown substances in the stock diet.
(10) Short-term toxicity tests were carried out for sulfide, selenide, and their methylated derivatives; the monomethylated forms were somewhat more toxic than the nonmethylated or dimethylated compounds.
(11) The microsomal activity apparently results from a Se-methyltransferase, possibly a dithiol protein, that methylates hydrogen selenide produced enzymically by the soluble fraction or non-enzymically when a sufficiently high concentration of GSH is used.
(12) The former is characterized by an increase in a 58 K selenoprotein, whereas the latter by an increase in volatile selenides.
(13) Intracerebral injections of both sodium selenide (Na2Se) and sodium selenite (Na2SeO3) have been successfully used; however, sodium selenite had a rather toxic effect on the injected tissue.
(14) In vitro experiments suggested that trace amounts of hydrogen selenide, which is an intermediate of selenite metabolism, probably induced hemolysis.
(15) Although arsenic decreased selenium toxicity under most conditions, there is a pronounced synergistic toxicity between arsenic and two methylated selenium metabolites, trimethylselenonium ion or dimethyl selenide.
(16) Sodium selenide is therefore recommended as the compound of choice.
(17) The production of acid-volatile selenide (apparently H2Se) was catalyzed by glutathione reductase in an anaerobic system containing 20 mM glutathione, 0.05 mM sodium selenite, a TPNH-generating system, and microgram quantities of highly purified yeast glutathione reductase.
(18) By using isolated guinea-pig taenia coli preparations, the effects of methylmercuric chloride and bis (methylmercuric) selenide on contractile responses to nerve and direct stimulation were investigated.
(19) These results are consistent with the hypothesis that the active form of Se may be selenide and that the selenide may form part of the active centre of an uncharacterized class of catalytically active non-haem-iron proteins that are protected from oxidation in vivo by vitamin E.
(20) The comparison between the 2-chloroethyl sulfides and selenides 1-4 revealed the markedly enhanced nucleophilicity of selenium (Se) over sulfur (S) by two or more orders of magnitude.
Selenium
Definition:
(n.) A nonmetallic element of the sulphur group, and analogous to sulphur in its compounds. It is found in small quantities with sulphur and some sulphur ores, and obtained in the free state as a dark reddish powder or crystalline mass, or as a dark metallic-looking substance. It exhibits under the action of light a remarkable variation in electric conductivity, and is used in certain electric apparatus. Symbol Se. Atomic weight 78.9.
Example Sentences:
(1) It was tested for recovery and separation from other selenium moieties present in urine using both in vivo-labeled rat urine and human urine spiked with unlabeled TMSe.
(2) Dietary factors affect intestinal P450s markedly--iron restriction rapidly decreased intestinal P450 to beneath detectable values; selenium deficiency acted similarly but was less effective; Brussels sprouts increased intestinal AHH activity 9.8-fold, ECOD activity 3.2-fold, and P450 1.9-fold; fried meat and dietary fat significantly increased intestinal EROD activity; a vitamin A-deficient diet increased, and a vitamin A-rich diet decreased intestinal P450 activities; and excess cholesterol in the diet increased intestinal P450 activity.
(3) Mice exhibiting this suppression of immunity had levels of blood glutathione peroxidase, serum selenium, and liver DNA, RNA and protein similar to mice receiving selenium only.
(4) Excess levels of selenium (2.5 and 5 ppm) in the vitamin E-deficient diet had little or no effect on spleen size or hematocrit of rats not receiving lead, but partially prevented the splenomegaly and anemia of red cells from either non-poisoned or lead-oisoned vitamin E-deficient rats, but not as effectively as vitamin E. These results show that vitamin E status of rats is more important that selenium status in determining response to toxic levels of lead.
(5) Plasma selenium concentration and glutathione peroxidase activity in the subjects who died within 1 year of screening were 89% and 88%, respectively, of the values among survivors (p less than 0.01).
(6) Although selenium deficiency in livestock is consequently now rare in Oregon, selenium-deficient soils and attendant selenium deficiency conditions have been reported near the Kesterson Wildlife Refuge in the Northern part of the San Joaquin Valley, California, where, paradoxically, selenium toxicity in wildfowl, nesting near evaporation ponds, occurred and attracted wide attention.
(7) The synthetic "C" nucleoside, tiazofurin (2-beta-D-ribofuranosylthiazole-4-carboxamide), its selenium analogue selenazofurin, and the related inhibitor of inosine 5'-phosphate (IMP) dehydrogenase, mycophenolic acid, are effective inducers of the terminal differentiation of HL-60 promyelocytic leukemia cells.
(8) Thus, in this population with intermediate selenium intake, low serum selenium is not associated with an excess risk of myocardial infarction.
(9) Liver, blood, kidney and lungs were found to contain most of the selenium, here also a two-phased elimination was observed.
(10) These findings suggest that neither serum levels of selenium nor those of retinol have an appreciable effect on the risk of cancer.
(11) The incidences of esophageal tumors were statistically not significant among rats on normal, high and low selenium intake (P greater than 0.05).
(12) Alteration of guinea pig erythrocyte superoxide dismutase activity by the dietary antioxidants ascorbic acid and selenium was investigated.
(13) The more severe was the PIH the lower was the selenium level.
(14) Significantly lower selenium values were observed in blood from colorectal cancer patients than from normal individuals (0.1349 ppm vs. 0.1502 ppm.
(15) Selenium-deficient rats were used to examine the nature of the oxidant stress.
(16) Although treatment with beta-carotene tended to decrease the incidence and number of large intestinal carcinomas, beta-carotene, selenium, esculin and eugenol all decreased the incidence of kidney nephroblastomas, the differences were not statistically significant.
(17) These studies were designed to measure leukotriene B4 (LTB4) production by polymorphonuclear leukocytes (PMN) from selenium (Se)-deficient and Se-adequate goats.
(18) Copper deficiency impairs cell-mediated immunity, as does selenium deficiency when it is associated with vitamin E lack.
(19) Many forms of selenium supplement are commercialized.
(20) The possibility that a sub-clinical deficiency of the trace element selenium might exist in a sample of the British population was examined by giving a selenium supplemented for 5 weeks.