Showing papers on "Selenium published in 1984"
TL;DR: Tests to indicate the presence of non-overt selenium deficiency in animals, such as blood seleniam measurements, are recommended for areas under suspicion from soil and crop analyses, and work should be carried out to quantify amounts of available seenium that are lost from soil systems.
320 citations
312 citations
TL;DR: It is concluded that dairy cow diets deficient of vitamin E may elevate incidence of clinical mastitis, and Selenium deficiency may result in greater duration of clinical symptoms, and selenium may interact with vitamin E.
306 citations
216 citations
Journal Article•
TL;DR: Histologically normal and neoplastic human breast tissues obtained from 25 patients at the time of mastectomy were homogenized in distilled water and 5-microliter aliquots dried on Formvar films for trace element analysis by energy-dispersive X-ray fluorescence.
Abstract: Histologically normal and neoplastic human breast tissues obtained from 25 patients at the time of mastectomy were homogenized (200 mg/ml) in distilled water and 5-microliter aliquots dried on Formvar films for trace element analysis by energy-dispersive X-ray fluorescence. The elements measured were calcium, vanadium, copper, zinc, iron, chromium, manganese, nickel, selenium, molybdenum, bromine, rubidium, strontium, mercury, arsenic, and lead. In general, significantly large increases (p less than 0.001) in calcium, vanadium, copper, zinc, selenium, and rubidium were found in breast tumors, with a less significant increase (p less than 0.05) for nickel. When a comparison was made between histologically normal and neoplastic tissues from the same individual, zinc and rubidium were found to be consistently higher in the tumor, whereas calcium, copper, and vanadium levels varied from normal to high. In no instance were the tissue changes in calcium, copper, zinc, or rubidium reflected in the blood levels, which were within normal limits. The distribution of calcium, copper, and zinc in urine varied among individuals with primary tumors; however, rubidium levels tended to be consistently elevated. An attempt is being made to correlate these various differences with the extent of the primary disease at the time of surgery, the postoperative tumor-free interval, and subsequent therapy.
207 citations
TL;DR: Growth data and liver and plasma Se GSH-Px activities indicated that the minimum selenium requirement of fingerling channel catfish fed adequate vitamin E was 0.25 mg Se/kg dry diet, and it appears that seenium supplementation of commercial catfish feeds is warranted.
Abstract: Two experiments were conducted in aquaria to determine the minimum dietary selenium requirement of fingerling channel catfish (Ictalurus punctatus). Casein-gelatin diets containing graded levels of supplemental selenium (as Na2SeO3) ranging from 0 to 15 mg/kg were fed to catfish for 15 weeks in experiment 1 to broadly define their selenium requirement and toxicity levels. Although growth of catfish was affected by dietary selenium level, significant differences in weight gain were not easily discernible due to variability among the groups of fish. Weight gain data generally indicated that the basal diet containing 0.06 mg Se/kg diet caused growth depression, and a supplemental selenium level of 15 mg/kg also caused a reduced growth response, which indicated selenium toxicity. Selenium concentrations in edible muscle tissue increased almost linearly with increasing dietary selenium levels. Liver and plasma selenium-dependent glutathione peroxidase (Se GSH-Px) activities indicated the selenium requirement of fingerling channel catfish was between 0.1 and 0.5 mg Se/kg diet. In experiment 2, casein-gelatin diets containing incremental levels of supplemental selenium were fed to catfish for 14 weeks to more precisely determine their minimum dietary selenium requirement. Growth data and liver and plasma Se GSH-Px activities indicated that the minimum selenium requirement of fingerling channel catfish fed adequate vitamin E was 0.25 mg Se/kg dry diet. Based on these data, it appears that selenium supplementation of commercial catfish feeds is warranted.
197 citations
TL;DR: Selenium injections and oral vitamin E supplementation prepartum were related to incidence of retained placenta, metritis, and cystic ovaries in a 2 X 2 factorial experiment and were effective for reducing the incidence of metritis and cystan ovaries during the early postpartum period.
193 citations
TL;DR: In this article, transition metal interferences in the determination of selenium using the hydride generation AAS technique were investigated in a system in which the seenium hydrides is generated in pure acid solution and comes into contact with the metal ions only in a second flask.
Abstract: Transition metal interferences in the determination of selenium using the hydride generation AAS technique were investigated in a system in which the selenium hydride is generated in pure acid solution and comes into contact with the metal ions only in a second flask. All investigated elements interfere in the ionic form with selenium when they are present in sufficiently high concentrations. Whenever a precipitation of the metallic species occurs, however, capture and decomposition of the selenium hydride by the finely dispersed metal appear to be the predominant mechanism of interference. In addition, this solid-gas reaction occurs typically at considerably lower interferent concentrations than the liquid-gas reaction of the ionic species. A substantial increase in the range of interference-free determination of selenium can be achieved by increasing the acid concentration of the solution for measurement because of the increased solubility of the reduced metal in the strong acid.
135 citations
124 citations
TL;DR: The levels of dietary selenium reported here as necessary to maintain balance in North American adults are considerably higher than those previously reported as needed for balance in adult women from New Zealand, a country where low selenum status is common.
106 citations
TL;DR: The kinetics of inhibition imply that glutathione peroxidase could be a target of gold drugs used in the treatment of rheumatoid arthritis and a very stable interaction should be obtained between Se(-II) and gold(I) through covalent bonding.
TL;DR: Both free-and protein-bound seleno-amino acids were identified and the initial steps of selenium incorporation seem to involve the use of the sulfur enzymatic machinery resulting in the replacement of some of the sulphur by selenum in both free amino acids and proteins.
TL;DR: The results of this study suggest that the metabolism of zinc, copper, manganese, and selenium is abnormal in thyroid diseases.
TL;DR: In this paper, a single-test-tube procedure for the fluorimetric determination of ng quantities of selenium with diaminonaphthalene, from small samples of animal origin is described.
TL;DR: The results indicate that regulation mechanisms exist, which in nutritional selenium deficiency cause reduced excretion of the element and priority of supply to certain tissues.
Abstract: In the tissues of rats fed a selenium-deficient diet the changes in the selenium content and the retention of the element after administration of a small amount of selenium to the depleted animals were determined. In the liver and in the erythrocytes, which are the main glutathione peroxidase pools, the decrease in the selenium content was great and the retention in the depleted rats only slightly increased in comparison with the control animals fed sufficient amounts of the element. In the testes and in the adrenals the decreases in the selenium content were the smallest, and here retention was about 15 times greater than in the control animals. Also in other tissues, such as the thymus, spleen, bone and kidney, retention was considerably increased in the depleted rats. The results indicate that regulation mechanisms exist, which in nutritional selenium deficiency cause reduced excretion of the element and priority of supply to certain tissues. This, in turn, leads to a redistribution of selenium in the organism and, as the glutathione peroxidase decreases to a greater extent than the selenium, also to a redistribution of the element among its different binding forms. As the selenium content is most probably kept up in particular in sites in which the element is most needed, the findings suggest important functions of selenium in these tissues.
Journal Article•
TL;DR: Although both sodium selenite and selenomethionine can inhibit some aspect of the postinitiation stage(s) of mammary carcinogenesis, selenium provided as sodium Selenite was the more effective and less toxic of the two chemicals.
Abstract: The relative effectiveness of either sodium selenite or selenomethionine in the inhibition of mammary carcinogenesis was studied in virgin female Sprague-Dawley rats. In one experiment, rats were given 50 mg of 1-methyl-1-nitrosourea per kg of body weight s.c. at 50 days of age. Beginning 7 days post-1-methyl-1-nitrosourea, they were assigned to a basal diet containing 0.1 ppm of selenium or basal diet supplemented to contain either 4, 5, or 6 ppm of selenium as sodium selenite or 5 or 6 ppm of selenium as selenomethionine. Selenium treatment was continued until termination of the study 135 days after 1-methyl-1-nitrosourea treatment. Sodium selenite, at the 5-ppm level, was the most effective chemopreventive agent. The highest level of selenomethionine (6 ppm) caused grossly apparent liver damage. No liver damage was noted in sodium selenite-treated rats. In a second experiment, rats were given 5 mg of 7,12-dimethylbenz(a)anthracene at 50 days of age. Beginning 7 days after 7,12-dimethylbenz(a)anthracene treatment, rats were assigned randomly to the control group or to one of two selenium treatment groups receiving either 3.4 ppm of selenium as sodium selenite or 3.4 ppm as selenomethionine in their drinking water. Selenium supplementation was continued throughout the study until its termination at 111 days postcarcinogen . Sodium selenite significantly reduced cancer incidence and the average number of cancers per rat. Treatment with selenomethionine was less effective and caused severe liver damage. Although both sodium selenite and selenomethionine can inhibit some aspect of the postinitiation stage(s) of mammary carcinogenesis, selenium provided as sodium selenite was the more effective and less toxic of the two chemicals. Increasing the dose of sodium selenite above 5 ppm did not enhance the inhibitory activity of selenium.
TL;DR: Multivariate analysis of the data showed that the decrease in blood and serum concentrations of selenium and the increase in whole blood cadmium concentrations in the cigarette smokers was independent of alcohol consumption and neither alcohol consumption nor smoking had an effect on the vitamin E concentrations.
Abstract: Fasting blood samples taken from 116 apparently healthy men aged 30-50 years were assayed for selenium, glutathione peroxidase activity, vitamin E, cadmium, lead, glucose, lipids, and albumin. Blood pressure was measured in each subject, and details of height, weight, smoking habits, and alcohol consumption were recorded. Multivariate analysis of the data showed that the decrease in blood and serum concentrations of selenium and the increase in whole blood cadmium concentrations in the cigarette smokers was independent of alcohol consumption. There was no correlation between blood selenium concentrations or glutathione peroxidase activities and the risk factors for cardiovascular disease. Neither alcohol consumption nor smoking had an effect on the vitamin E concentrations. There was a strong association, however, between vitamin E and serum lipid concentrations, although the increase in triglyceride concentrations in the smokers was not matched by a comparable increase in vitamin E. The possible role of selenium in the aetiology of heart disease remains unresolved.
TL;DR: Selenium supplementation corrected the anemia, prevented Heinz body formation, increased the body weight of cows and calves, and elevated blood selenium.
Abstract: Cattle grazing St. Augustine grass growing on peaty muck soils in the Florida Everglades developed anemia associated with the presence of Heinz bodies and suboptimal concentrations of selenium in blood. Selenium supplementation corrected the anemia, prevented Heinz body formation, increased the body weight of cows and calves, and elevated blood selenium. This may be the first recorded example of widespread anemia in a population due to selenium deficiency.
TL;DR: Daily excretion levels in healthy persons and in pathological or experimental conditions are compiled, and the literature on the chemical species of the element in urine is critically reviewed.
TL;DR: In this article, a preferential reduction of Fe(III) to Fe(II), which inhibits the precipitation of the interfering nickel as the metal, is proposed mechanism of reaction, which can extend the range of interference-free determination for these elements by three orders of magnitude.
Abstract: Iron(III) has a releasing effect on the interference due to nickel on the determination of arsenic and selenium. Together with an increase in the acid concentration of the solution for measurement, this effect can extend the range of interference-free determination for these elements by three orders of magnitude. A preferential reduction of Fe(III) to Fe(II), which inhibits the precipitation of the interfering nickel as the metal, is the proposed mechanism of reaction.
TL;DR: Differences in the mode of absorption of selenite and selenate, and in the distribution and chemical form of Se found in the plant after absorption, probably account for this disparity in toxicity.
Abstract: Summary
Shoot concentrations of Se associated with a 10% reduction in dry matter yield were established for perennial ryegrass (Loliumperenne L.) and white clover (Trifolium repens L.) grown in sand culture. Selenite– treated plants had lower shoot concentrations of Se than those treated with selenate; the critical toxic values associated with a 10% reduction in growth were 48 and 320μg Se g− 1 dry matter shoots for ryegrass plants, and 160 and 330μeg1 dry matter shoots for white clover plants, respectively. Differences in the mode of absorption of selenite and selenate, and in the distribution and chemical form of Se found in the plant after absorption, probably account for this disparity in toxicity. While both selenate and selenite increased the Se concentration in the tissues of the plants to high levels, a greater proportion of the absorbed Se was transported to the shoots of the selenate-treated plants than of those treated with selenite. Increasing supplies of selenate were associated with a reduction in chlorophyll content. Contrary to the concept of a common uptake mechanism in the roots for selenate and sulphate, increasing supplies of selenate had a synergistic effect on S concentrations in the shoots rather than the expected antagonistic effect.
TL;DR: Procedures for determination of selenium in urine samples are reviewed and basic problems encountered in sampling and sample-treatment are discussed.
TL;DR: In this paper, it was found that the different valency states of selenium are not stabilized to the same extent by frequently applied matrix modifiers like nickel or copper, which may explain pre-atomization losses and high characteristic mass data reported previously.
TL;DR: The viability of human breast cancer cells (cell lines MCF-7 and MDA-MB 231) was inhibited in vitro in a dose-dependent manner by selenium supplementation, however, a normal diploid human cell line (MRC-5) was relatively resistant to seenium supplementation.
TL;DR: Patients who were treated chronically, with VPA as the sole anticonvulsant medication, had decreased plasma selenium levels, which could be due to decreased seenium concentrations when mechanisms for protection against peroxidative damage are not fully developed.
Abstract: Side effects of treatment with the anticonvulsant valproic acid (VPA) suggested the possibility of alteration of trace metal status. Administration of VPA for 1 week produced significant depletion of zinc and selenium in plasma of rats and a one-third reduction of hepatic selenium. Patients who were treated chronically, with VPA as the sole anticonvulsant medication, had decreased plasma selenium levels. Most cases of VPA-associated hepatotoxicity occur in children. This could be due to decreased selenium concentrations when mechanisms for protection against peroxidative damage are not fully developed.
Journal Article•
TL;DR: The results indicate that one of the mechanisms of selenium-mediated inhibition of carcinogenesis may be due to an inhibition of cell proliferation of responsive cells.
Abstract: Previous results have documented that Na2SeO3 has a biphasic effect on the growth of mammary cells in vitro. In the experiments reported herein, the effects of selenium on several parameters of cell proliferation in the YN-4 mouse mammary cell line were investigated. The biphasic effect of selenium on cell growth was confirmed; i.e., 5 X 10(-8) M selenium stimulated cell growth, whereas 5 X 10(-6) M delayed cell growth and 5 X 10(-5) M was cytotoxic. The inhibition of cell growth by 5 X 10(-6) M selenium was reversible when this dose was removed from the growth medium. The increased cell growth at 5 X 10(-8) M selenium was reflected by an increased cell number, increased uptake of [3H]thymidine into DNA, increased DNA labeling index, and an increased rate of DNA synthesis. The decreased cell growth at 5 X 10(-6) M selenium was reflected by a decrease in all of these parameters of cell growth kinetics. The differential effects of selenium were manifested by 48 hr after addition of selenium to the cell culture medium. The results indicate that one of the mechanisms of selenium-mediated inhibition of carcinogenesis may be due to an inhibition of cell proliferation of responsive cells.
TL;DR: The accuracy of the determination of selenium in human body fluids by hydride-generation a.s.a. as discussed by the authors depends critically upon the sample decomposition-method used.
TL;DR: The results demonstrate that processes other than those related to GSH-Px take place in a later phase of selenium deficiency in mouse liver with a chronologically common beginning and different repletion and depletion kinetics as well as the different need of these processes for the trace element are discussed.
TL;DR: In this article, the authors demonstrate the volatilization of selenium in two agronomic plant species, Agrostis tenuis Sibth and Hordeum vulgare L. c.v.