Showing papers on "Selenium published in 1988"
157 citations
TL;DR: The results indicate that the chemical forms of dietary Se can have a marked influence on biological responses, including bioavailability of dietary selenium, as well as in tissues of rats fed SeM rather than selenite.
Abstract: Weanling rats were fed a basal diet or this diet plus 02, 10, 20 or 40 mg/kg selenium (Se) as either selenite or selenomethionine (SeM) Except at the 02 mg/kg Se level, Se accumulated in all tissues at higher levels when SeM was fed than when selenite was given, and the magnitude of difference became more pronounced with increasing levels of dietary Se This was particularly true for muscle and brain Se levels in whole blood, testes, kidney and lungs were not significantly different between rats fed 02 mg/kg Se as selenite or as SeM, but the Se levels in liver, muscle and brain were higher in rats fed SeM Although the tissue Se concentrations differed markedly, there were no differences in the glutathione peroxidase (GPX) activity in tissues of rats fed SeM rather than selenite The percentage of Se associated with GPX was lower in all tissues from rats fed SeM than in those from rats fed selenite These results indicate that the chemical forms of dietary Se can have a marked influence on biological responses, including bioavailability of dietary Se
154 citations
TL;DR: Enrichment of fertilizers with sodium selenate seems an efficient and predictable way of increasing the Se concentration of foods and the Se intake of people in low-Se areas.
143 citations
TL;DR: A direct method for determination of selenium in serum by graphite-furnace atomic absorption spectrophotometry with deuterium background correction with palladium modifier is described, which is applicable to neonatal populations.
Abstract: We describe the development of a direct method for determination of selenium in serum by graphite-furnace atomic absorption spectrophotometry with deuterium background correction. We include palladium modifier to stabilize selenium in the presence of a strong reducing agent. Spectral interferences from iron are not evident in this system. Because an analysis requires only 20 microL of serum or plasma, the method is applicable to neonatal populations. At a selenium concentration of 0.75 mumol/L (approximately the mean found in our pre-term infants), the within-run CV is 5.3%. For a concentration of 1.83 mumol/L, which approximates our normal adult mean, within-run and between-run CVs are 2.7% and 3.4%. Accuracy is demonstrated by analytical recoveries ranging from 96% to 102%. We present reference values for pre-term and term infants, and age-specific ranges for infants to adults.
135 citations
135 citations
TL;DR: Age- and sex-specific reference intervals based on the 0.025 and 0.975 fractiles of data derived from a healthy pediatric population are presented for zinc, copper, selenium, iron, ferritin, retinol, alpha-tocopherol, and related analytes in serum.
Abstract: Age- and sex-specific reference intervals based on the 0.025 and 0.975 fractiles of data derived from a healthy pediatric population are presented for zinc, copper, selenium, iron, ferritin, retinol, alpha-tocopherol, and related analytes in serum. Age was an important covariate for copper, selenium, retinol, and tocopherol, and ferritin in boys. Strong correlations were found between retinol and retinol-binding protein, prealbumin (transthyretin), alpha-tocopherol, and selenium. Tocopherol was highly correlated with both cholesterol and triglycerides. We found no relationship between serum zinc and either retinol or retinol-binding protein. Despite exclusion of children in whom anemia, microcytosis, or variant hemoglobins were found, the 0.025 fractile for iron in several age groups was even less than the concentration considered to indicate poor iron nutritional status.
128 citations
TL;DR: In this article, the palladium nitrate-magnesium nitrate modifier is applied to the analysis of water, and a common set of conditions for the determination of As, Cu, Mn, Pb, Sb and Se can be used.
Abstract: If the palladium nitrate-magnesium nitrate modifier is applied to the analysis of water, a common set of conditions for the determination of As, Cu, Mn, Pb, Sb and Se can be used. For Cd and Tl lower pyrolysis and atomisation temperatures are required. Twenty-one possible interferents were investigated at maximum concentrations between 1 and 500 mg l–1 and only two were found to have an effect greater than ±10%. The determination of Tl was affected by sodium chloride at concentrations above 100 mg l–1, hence the addition of Li is recommended to control this interference. Five mg l–1 of Fe decreased the Se signal by about 15% when deuterium-arc background correction was used but had no influence in an instrument with Zeeman-effect background correction. For an instrument with continuum source background correction it was also necessary to determine Cu using the secondary resonance line at 327.4 nm because of spectral interference due to Pd at the primary resonance line. Precision was about 1% in the optimum working range and between 2 and 5% at 0.05 A s. Detection limits (2.33 σ) were 1.2 µg l–1 for As, 0.02 µg l–1 for Cd, 0.3 µg l–1 for Cu, 0.45 µg l–1 for Mn and Pb, 1.2 µg l–1 for Sb, 0.6 µg l–1 for Se and 0.8 µg l–1 for Tl.
124 citations
TL;DR: Findings indicate that selenomethionine is considerably more teratogenic and generally more embryotoxic than sodium selenite, probably due to higher uptake of selenometrichions in hatchlings.
Abstract: Mallards (Anas platyrhynchos) were fed a control diet, diets containing 1, 5, 10, or 25 ppm Se as sodium selenite, or a diet containing 10 ppm Se as seleno-DL-methionine in the first of two experiments. Selenium at 10 ppm as selenomethionine or 25 ppm as sodium selenite caused a 40-44% decrease in the total number of eggs that hatched compared to controls. Selenium at 25 ppm (sodium selenite) resulted in a 19% decrease in mean embryonic weight at 18 d of incubation, accompanied by a 6% decrease in crown-rump length. Ten parts per million Se as selenomethionine was more teratogenic than sodium selenite at 25 ppm. Selenomethionine (10 ppm Se) resulted in an incidence of 13.1% malformations that were often multiple, whereas sodium selenite (10 and 25 ppm Se) resulted in 3.6 and 4.2% malformations. The teratogenicity of selenomethionine was confirmed in a second experiment in which mallards received 1, 2, 4, 8, or 16 ppm Se as selenomethionine, resulting in 0.9, 0.5, 1.4, 6.8, and 67.9% malformations, respectively. These malformations included hydrocephaly, microphthalmia, lower bill defects, and foot defects with ectrodactyly. Both forms of selenium increased the incidence of edema and stunted embryonic growth. Selenomethionine (10 ppm Se) resulted in a significant increase of approximately 40% in plasma glutathione peroxidase activity and a 70% increase in sorbitol dehydrogenase activity (indicative of hepatotoxicity) in hatchlings. Sodium selenite (25 ppm Se) resulted in fourfold elevation in plasma uric acid concentration, indicative of renal alteration. Selenomethionine accumulated much better in eggs than did sodium selenite. These findings indicate that selenomethionine is considerably more teratogenic and generally more embryotoxic than sodium selenite, probably due to higher uptake of selenomethionine.
119 citations
TL;DR: Selenite was also a mutagen in the tester strain TA104, in which a number of other oxidizing agents have also been found to be mutagens, consistent with a model in which the reactions of selenite and intracellular thiols with concomitant production of active oxygen species are the primary causal agents ofselenite mutagenicity and toxicity in S. typhimurium.
Abstract: The mechanisms of selenite toxicity and mutagenicity in S typhimurium have been characterized In contrast to previous reports, selenite toxicity was shown not to involve nonspecific incorporation into protein via the sulfur metabolic pathways Selenite toxicity was, however, shown to involve its ability to act as an oxidizing agent, primarily through reactions with sulfhydryls Strains which lack glutathione (GSH) are more sensitive to killing by sulfhydryl reagents The selenite sensitivity of such a mutant was a biphasic phenomenon The mutant was much more sensitive than a strain which contained GSH at lower selenite concentrations whereas, at higher concentrations, the mutant was much more resistant to selenite The mechanism of selenite toxicity at lower concentrations in this mutant thus appeared to involve damage to intracellular sulfhydryls The sensitization to higher doses of selenite by GSH could be explained by the generation of toxic oxygen species The in vitro reactions of selenite with both cysteine and GSH readily produced H2O2 and O2- A S typhimurium strain which overproduces superoxide dismutase (SOD) and catalase was more resistant to high concentrations of selenite, but not killing by the lower doses Pretreatment of cells with a nonlethal dose of selenite induced the synthesis of proteins which protected the cells from killing by H2O2 or high doses of selenite Selenite was also a mutagen in the tester strain TA104, in which a number of other oxidizing agents have also been found to be mutagens These results were consistent with a model in which the reactions of selenite and intracellular thiols with concomitant production of active oxygen species are the primary causal agents of selenite mutagenicity and toxicity in S typhimurium
115 citations
TL;DR: Enterohepatic reabsorption of selenium from the bile appears to be a significant mechanism of conserving dietary Se and to maintain Se balance at comparatively low dietary Se intakes.
Abstract: The selenium concentrations were determined in liver, kidney, skeletal muscle, heart, brain, prostate, testis, bile, lung, and spleen of German traffic accident victims. In addition, the nitrogen and phosphorus contents were determined in the same organs and tissues. On a per-weight unit basis, the highest selenium concentration was found in kidney. However, this corresponds to only 4% of the total body selenium. Most of the whole body selenium (50%) is present in skeletal muscle, which thus appears to act as a selenium storage organ. However, there is also evidence that selenium is required for muscle function. In plasma and interstitial fluid, .450 mg of Se, or 7.5% of the total body selenium is present. A comparison of the organ Se concentrations of the German traffic accident victims with the selenium concentrations of the same human organs as reported in different countries indicates that the organ concentrations of West Germans are comparable to that of the population of New Zealand, a low-Se country, and significantly lower than that observed in the organs of American, Canadian, and especially Japanese subjects. The international comparison of the organ selenium concentrations also revealed that the selenium uptake of kidney is higher at low- and adequate dietary Se intakes and lower if the dietary Se supply is high, as is the case for Japanese subjects. Estimates of the daily excretion of selenium with the bile indicate that the amounts are three times higher than the daily urinary losses and in the same order of magnitude as the daily dietary selenium intakes. Enterohepatic reabsorption of selenium from the bile appears to be a significant mechanism of conserving dietary selenium and to maintain Se balance at comparatively low dietary Se intakes.
110 citations
TL;DR: Data collected indicate that indigenous bacteria have a significant role in the biogeochemical cycling of selenium.
Abstract: Samples collected from Kesterson Reservoir were screened for bacterial presence and selenate reduction capability. Selenate concentrations of 100 mg/liter were not toxic to indigenous bacteria. Of the 44 samples collected, 20 possessed microbial populations capable of reducing selenate. Reduction was observed in 4% of the water samples, 92% of the sediment samples, and 100% of the soil samples. Microbial reduction of 100 mg of selenate per liter was complete within 1 week of incubation. Up to 75 mg of selenate per liter was reduced beyond selenite to an insoluble red precipitate. Data collected indicate that indigenous bacteria have a significant role in the biogeochemical cycling of selenium.
TL;DR: Synthese des composes du titre a partir de Li, Na ou K and de selenium, reagissent avec des hydrocarbures halogenes pour conduire a des seleniures and des diseleniures organiques as discussed by the authors.
Abstract: Synthese des composes du titre a partir de Li, Na ou K et de selenium; les composes du titre reagissent avec des hydrocarbures halogenes pour conduire a des seleniures et des diseleniures organiques
TL;DR: Data suggest a general role for this novel enzyme in the synthesis of onium compounds with increased aqueous solubility helpful in their excretion in selenium detoxification.
TL;DR: The association between serum selenium concentration and risk of cancer was studied in a nested case control study and the risk of developing adenocarcinomas does not seem to be influenced by serum seenium concentration.
Abstract: The association between serum selenium concentration and risk of cancer was studied in a nested case control study. Case control pairs came from a population of 9364 people examined in 1979. During the six year follow up, 60 men and women aged between 20-54 at the time of blood sampling, who had been free of malignant disease, developed cancer. The mean serum selenium concentration of 1.56 mumol/l (123.2 micrograms/l) in patients was not significantly different from that in controls (1.63 mumol/l (128.7 micrograms/l]. The difference in mean selenium concentration was largest and most significant for haematological malignancies alone. The difference in selenium concentrations in cases of fatal cancer compared with controls was significant (p less than 0.01). The risk of developing adenocarcinomas does not seem to be influenced by serum selenium concentration.
TL;DR: Based on comparisons of residues of selenium in livers of surviving and dead ducklings, concentrations in the liver were not diagnostic of death due to se lenium poisoning, and selenum-induced starvation may have been related to duckling mortality.
Abstract: The toxicity of selenomethionine and sodium selenite to mallard ducklings (Anas platyrhynchos) was measured by feeding each form from hatching to six weeks of age at dietary concentrations of 0, 10, 20, 40, and 80 ppm selenium. At 80 ppm selenium, sodium selenite caused 97.5% mortality by six weeks and selenomethionine caused 100% mortality. At 40 ppm, these two forms of selenium caused 25 and 12.5% mortality. No mortality occurred at 10 or 20 ppm. Diets containing 20, 40, or 80 ppm selenium in both forms caused decreases in food consumption and growth. The only statistically significant effect of 10 ppm selenium was with sodium selenite, which resulted in larger livers than controls. Selenomethionine was more readily stored in the liver than sodium selenite at levels above 10 ppm selenium in the diet. Based on comparisons of residues of selenium in livers of surviving and dead ducklings, concentrations in the liver were not diagnostic of death due to selenium poisoning. Because both forms of selenium resulted in severe reductions in food consumption, selenium-induced starvation may have been related to duckling mortality. It was not clear whether either form of selenium at 10 ppm in the diet resulted in a leveling off of selenium concentrations in the liver within six weeks.
TL;DR: It is concluded that this selenium-dependent enzyme may be important in the protection of bovine spermatozoa against damage caused by oxygen radicals, while in man such a mechanism is not functional.
Abstract: High levels of selenium and glutathione peroxidase (GSH-Px) were found in bull seminal plasma but low concentrations in human seminal plasma. In man the seminal plasma selenium was associated with two macromolecules separable by gel filtration, but no GSH-Px was found in the same fractions. Selenium in bull seminal plasma was associated with two proteins, which could be separated by gel filtration and anion exchange chromatography. Both macromolecules coeluted with GSH-Px activity and had identical optima at pH 7.0. Their responses to thermal treatment, however, differed. Seminal vesicle secretory fluid in the bull contained both these proteins, while the larger molecule was also found in fractionations of ampulla, prostate and Cowper's glands. The larger enzyme form is evidently a tetramer of the smaller one. Both enzyme forms were extremely sensitive to heavy metals and some divalent metal ions. GSH caused an activation while other reducing agents were suppressive. Triton X-100 had no effect, while sodium deoxycholate was inhibitory. These properties are typical for a phospholipid hydroperoxide GSH-Px. It is concluded that this selenium-dependent enzyme may be important in the protection of bovine spermatozoa against damage caused by oxygen radicals, while in man such a mechanism is not functional.
TL;DR: The demonstration that low selenium status can cause imbalances in thyroid hormone metabolism may provide an explanation for some of the effects of the deficiency.
TL;DR: It is concluded that patients manifesting infection with human immunodeficiency virus have evidence of selenium deficiency as determined by diminished plasma and erythrocyte levels and glutathione peroxidase activity.
Abstract: Severe protein-calorie malnutrition is common in patients with AIDS and could contribute to the progressive deterioration characteristic of that disease. Selenium deficiency could also have a negative impact on immune function and other organ functions vital for recovery from infectious diseases. Therefore, to assess any role for selenium in AIDS we determined plasma and erythrocyte selenium levels and glutathione peroxidase activity in 13 patients with AIDS compared to 8 patients with AIDS-related complex (ARC) and 14 healthy controls. Plasma selenium levels were significantly reduced in AIDS patients compared to controls (p less than .0001) and to ARC (p less than .02). Erythrocyte selenium levels in both AIDS and ARC were also reduced compared to controls (p less than .02), but not to each other. Glutathione peroxidase activity in AIDS was 28.9 +/- 1.4 U/g Hb vs 38.4 +/- 6.9 in ARC (p = NS) and 52.3 +/- 1.7 in controls (p less than .0001 vs AIDS; p less than .02 vs ARC). When all groups were combined, there were significant correlations between total lymphocyte count and both plasma selenium (r = .53; p less than .002) and erythrocyte glutathione peroxidase activity (r = .65; p less than .0001). In addition, strong correlations were noted between plasma selenium and serum albumin (r = .68; p less than .0001), plasma selenium and glutathione peroxidase (r = .77; p less than .0001), and glutathione peroxidase and hematocrit (r = .66; p less than .0001). In AIDS or ARC, no correlations between selenium with disease duration or weight loss were present. We conclude that, in comparison to normals, patients manifesting infection with human immunodeficiency virus have evidence of selenium deficiency as determined by diminished plasma and erythrocyte levels and glutathione peroxidase activity. These abnormalities are most marked in patients with AIDS, but are also present in patients with AIDS-related complex. Selenium deficiency has important implications for the progression and pathogenesis of clinical disease in AIDS.
TL;DR: An intake of 150-300 micrograms of Se daily is considered to be adequate to protect the human organism without exhibiting the toxic properties of this element.
TL;DR: Mise en evidence de la presence of selenium sous forme de selenomethionine dans des concentres et isolats de proteines de soja delipide as mentioned in this paper.
Abstract: Mise en evidence de la presence de selenium sous forme de selenomethionine dans des concentres et isolats de proteines de soja delipide
TL;DR: It is shown that the absence of selenium incorporation into suppressor tRNA reduces the efficiency of suppression of nonsense codons in certain contexts and when wobble base pairing is required, indicating that one function of mnm5Se2U in tRNA may be in codon-anticodon interactions.
Abstract: Selenium is a constituent in Escherichia coli of the anaerobic enzyme formate dehydrogenase in the form of selenocysteine. Selenium is also present in the tRNA of E. coli in the modified base 5-methylaminomethyl-2-selenouracil (mnm5Se2U). The pathways of bacterial selenium metabolism are largely uncharacterized, and it is unclear whether nonspecific reactions in the sulfur metabolic pathways may be involved. We demonstrated that sulfur metabolic pathway mutants retain a wild-type pattern of selenium incorporation, indicating that selenite (SeO32-) is metabolized entirely via selenium-specific pathways. To investigate the function of mnm5Se2U, we isolated a mutant which is unable to incorporate selenium into tRNA. This strain was obtained by isolating mutants lacking formate dehydrogenase activity and then screening for the inability to metabolize selenium. This phenotype is the result of a recessive mutation which appears to map in the general region of 21 min on the Salmonella typhimurium chromosome. A mutation in this gene, selA, thus has a pleiotropic effect of eliminating selenium incorporation into both protein and tRNA. The selA mutant appears to be blocked in a step of selenium metabolism after reduction, such as in the actual selenium insertion process. We showed that the absence of selenium incorporation into suppressor tRNA reduces the efficiency of suppression of nonsense codons in certain contexts and when wobble base pairing is required. Thus, one function of mnm5Se2U in tRNA may be in codon-anticodon interactions.
Patent•
15 Nov 1988TL;DR: In this paper, a method for reducing the amount of a first contaminant and second contaminant in a solution to environmentally safe levels, said solution having a substantially greater amount of the first contaminants than the second contaminants, was disclosed.
Abstract: A method is disclosed for reducing the amount of a first contaminant and second contaminant in a solution to environmentally safe levels, said solution having a substantially greater amount of the first contaminant than the second contaminant. The method comprises: contacting the solution with an activated or calcined product of a compound having the formula A 6 B 2 (OH) 16 C.4H 2 O, wherein A is a divalent metal cation, B is a trivalent metal cation and C is a mono- to tetravalent anion. The method further comprises separating the solution from the contacted product. The method is particularly useful for removing both selenium and sulfate, arsenic and sulfate, or arsenic and phosphate from a waste water stream. An unpredicted preference for selenium and arsenic, in the presence of other contaminants including sulfate and phosphate, was also shown herein.
TL;DR: The results indicate that the form of Se administered will influence the form in the tissues, the percentage of Se with GPx and the body burden of Se.
TL;DR: Dietary vitamin E supplementation had a similar effect on the antibody response to tetanus toxoid in ewes, though no additive effect was seen when vitamin E was given together with selenium.
TL;DR: Elevated levels of selenium have resulted in the degradation of several ecosystems and have been linked to reproductive impairment in important fish and waterfowl populations in several lakes and reservoirs, indicating the need for a better understanding of the bioaccumulation of Selenium by aquatic organisms.
Abstract: Elevated levels of selenium have resulted in the degradation of several ecosystems and have been linked to reproductive impairment in important fish and waterfowl populations in several lakes and reservoirs, indicating the need for a better understanding of the bioaccumulation of selenium by aquatic organisms. Because space limitations prevent an exhaustive review, this paper focuses on the processes and mechanisms of bioconcentration and biomagnification. Comparative uptake and accumulation of selenite, selenate, and selenomethionine are examined, as well as the relative importance of waterborne and foodborne exposure. The observed toxicity of selenium in lakes and reservoirs is briefly discussed. Finally, this information is summarized, pointing out key trends in the uptake and accumulation of selenium. Perhaps the most important information generated by this review involves comparative metabolism of selenite and selenate; selenite is readily reduced and metabolized, while reduction and metabol...