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PubMed1990

The effect of selenium ions on the catabolism of prostaglandin E2 in rabbit kidney cortex.

The effect of selenium ions on the catabolism of prostaglandin E2 by 15-hydroxy prostaglandin dehydrogenase and prostaglandin delta 13 reductase in rabbit kidney cortex was examined. Selenium ions had no effect on the 15-hydroxy prostaglandin dehydrogenase activity. On the other hand, selenium ions inhibited the prostaglandin delta 13 reductase activity at concentrations ranging from 0.05 to 0.5 mM. The effect was concentration-dependent. The inhibition by selenium ions was non-competitive with regard to NADH and 15-keto PGE2, respectively. These results suggest that selenium ions have the potential to increase 15-keto PG levels in the kidney by inhibiting the prostaglandin delta 13 reductase activity and that such action of selenium ions may participate in renal damage of selenium poisoning.

Animals↗
PubMedDate not supplied

[Functional state of selenium during screening of pregnant women in the second half of pregnancy].

Activity of selenium-dependent glutathione peroxidase and content of selenium in blood were studied during the pregnant women screening. 260 healthy women with pregnancy of 20-34 weeks without any clinical manifestations of hestosis were examined. Decrease of the enzyme activity, correlating with the selenium content, was detected in blood of women with selenium content, was detected in blood of women with clinical forms of hestosis. At the same time, the enzyme activation simultaneously with normal concentration of selenium in blood, were found in some women at the initial steps of toxicosis. Glutathione peroxidase reaction appears to correlate with selenium content during the preclinical steps of hestosis development. Content of selenium in blood of pregnant women as low as 80 pg/ml may be among the risk factors responsible for impairment of the glutathione antioxidation system under conditions of late toxicosis in pregnant women.

Adolescent↗
PubMed1990

A prospective study of selenium status and breast cancer risk.

Low dietary intake of selenium has been proposed as a risk factor for breast cancer. To address this hypothesis, we collected toenail clippings from 62,641 women in the Nurses' Health Study cohort who were free from cancer (other than nonmelanoma skin cancer) in 1982 and 1983. The selenium concentration in nails has been shown to reflect dietary intake of selenium. During 53 months of follow-up, 434 cases of breast cancer were diagnosed among women who had submitted a set of toenail clippings, and we matched one control free from breast and other cancers to each case. The mean selenium level in toenails in the cases (0.823 microgram/g; SD, 0.197) was almost identical to that of the controls (0.821 microgram/g; SD, 0.174). After controlling for known breast cancer risk factors, the relative risk for women in the highest quintile of selenium as compared with the lowest quintile was 1.10 (95% confidence interval, 0.70 to 1.72) and there was no trend across quintiles. Results were similar for both premenopausal and postmenopausal women. Although these data do not exclude a possible influence of selenium intake before adulthood on subsequent risk of breast cancer, selenium intake later in life is not likely to be an important factor in the etiology of breast cancer.

Adult↗
PubMed1989

Effect of mercury on selenium binding to rat lens proteins in vitro.

The effect of mercury in the incubation medium on selenium influx, efflux and distribution was studied in eye lenses of 14-day-old rats. The presence of mercury did not affect the uptake of selenium into a water-soluble protein fraction but increased considerably its content in water-insoluble proteins and thus also the selenium influx into experimental lenses. The efflux from experimental lenses yielded significantly lower amounts of released selenium, most of the selenium being bound to proteins. In contrast, efflux experiments with control lenses showed most of the selenium to be in the medium in the form of free anions. The selenium content in experimental lenses decreased after the efflux only in the fraction of water-soluble proteins, while the decrease in control lenses was found in both fractions and was relatively higher in water-insoluble proteins. During both influx and efflux experiments the lenses of both groups released a small of proteins, but no difference found between the two groups.

Animals↗
PubMed1989

Decreased selenium levels in acute myocardial infarction.

To study the association between selenium status and the risk of myocardial infarction, we compared plasma, erythrocyte, and toenail selenium levels and the activity of erythrocyte glutathione peroxidase among 84 patients with acute myocardial infarction and 84 population controls. Mean concentrations of all selenium measurements were lower in cases than controls. The differences were statistically significant, except for the plasma selenium level. A positive trend in the risk of acute myocardial infarction from high to low toenail selenium levels was observed, which persisted after adjustment for other risk factors for myocardial infarction. In contrast, erythrocyte glutathione peroxidase activity was significantly higher in cases than controls (31.3 +/- 8.4 U/g of hemoglobin and 28.0 +/- 8.1 U/g of hemoglobin, respectively). Because the toenail selenium level reflects blood levels up to one year before sampling, these findings suggest that a low selenium status was present before the infarction and, thus, may be of etiologic relevance. The higher glutathione peroxidase activity in the cases may be interpreted as a defense against increased oxidant stress either preceding or following the acute event.

Aged↗
PubMed1988

An apparent phosphate selenium interaction in weaner sheep.

The severity of selenium dependent nutritional myopathy in weaner sheep was markedly increased by the ruminal infusion of soluble phosphate (6.0 g d-1). Liver selenium concentration was also significantly lower in the sheep infused with sodium phosphate than in sheep fed the same diet and infused with sodium chloride. There were no significant differences in the selenium concentrations of other tissues examined (kidney, heart, skeletal muscle, blood). Blood glutathione peroxidase (GSH.Px) activity in the sheep affected with nutritional myopathy was considerably higher than values generally accepted to indicate a selenium deficiency. The results indicated that there was an interaction in the animal between selenium and phosphate leading to lower liver selenium concentrations. Results obtained from sheep intraruminally dosed with 75[Se]selenate suggested that an interaction between selenium and phosphate could also occur in the gastrointestinal tract.

Animals↗
PubMed1988

Improved survival in murine lupus as the result of selenium supplementation.

Selenium is a trace mineral and a required nutrient for animals and humans. Selenium intake appears to be inversely correlated with the risk of developing cancer. Since immunological effects of selenium have been described we studied the capacity of selenium to modify the lupus-like disease of NZB/NZW female mice. Our data indicate that selenium supplementation (sodium selenite 4 parts per million in the drinking water) significantly improves survival in these autoimmune mice: mean survival 55.6 +/- 4.6 weeks (mean +/- s.e.) for treated mice versus 36.1 +/- 1.9 weeks for controls (P less than 0.04). Additionally, selenium supplemented mice had significantly higher natural killer cell activity (P less than 0.001). However, no obvious effects of selenium supplementation on autoantibody production were observed.

Animals↗
PubMedDate not supplied

Selenium status, lipid peroxides concentration, and glutathione peroxidase activity in the blood of power station and rubber factory workers.

Concentration of selenium in whole blood and plasma, lipid peroxides in plasma, and glutathione peroxidase activities in red blood cell hemolysates and plasma were determined in 49 coal power plant workers and in 50 rubber factory workers. The results were compared with those obtained for 58 nonindustrial controls. Whole blood selenium was significantly lower and plasma lipid peroxides were significantly higher in power plant workers when compared to the nonindustrial group. In the rubber factory workers, whole blood selenium and red blood cells and plasma glutathione peroxidase activities were significantly lower than in the control group. Urinary output of selenium was also significantly decreased in rubber factory workers. Slightly elevated lipid peroxides were also observed in that group. It seems reasonable to conclude that the lower blood selenium and decreased urinary output of this element may result from increased loss of selenium with perspiration. No correlation has been observed between selenium concentration and glutathione peroxidase activity and between enzyme activity and lipid peroxides concentration in the industrial group.

Adult↗
PubMed1986

Selenium in pregnancy: effect of maternal drinking.

To study the effect of drinking alcohol during pregnancy on serum selenium, selenium concentrations were measured in 41 women (ten abstinent, 31 problem drinkers) throughout pregnancy as well as in 24 nonpregnant abstinent women. In abstinent pregnant women, serum selenium decreased with advancing gestational age, a pattern not affected by moderate maternal drinking (42 to 126 g of ethanol weekly, N = 14). Seventeen women drank heavily (more than 140 g of ethanol weekly), and nine of them (53%) gave birth to infants with fetal alcohol syndrome. The women with infants having fetal alcohol syndrome had higher (P less than 0.05) selenium levels than the abstinent controls both at the 25th to 32nd (63.3 +/- 6.2 versus 56.6 +/- 4.4 micrograms/L) and at the 33rd to 40th gestational weeks (58.6 +/- 3.4 versus 53.5 +/- 5.9 micrograms/L). The selenium levels in umbilical serum were 20 and 33% lower than in maternal serum of abstinent and drinking women, respectively. However, alcohol-damaged newborns did not demonstrate any further decrease in selenium levels. Thus, heavy maternal drinking is accompanied by increased maternal and decreased umbilical concentration of selenium.

Alcohol Drinking↗
PubMed1987

Abrogation of adriamycin-induced cardiotoxicity by selenium in rabbits.

Adriamycin-induced cardiomyopathy in rabbits was produced by intravenous injections of the drug with a short therapeutic schedule (3 mg/kg body wt administered as four intermittent doses). Animals receiving selenium supplementation of Adriamycin showed preservation of the normal pattern of the heart histologic picture. The protective effect of selenium was accompanied by increased selenium levels in the plasma and the heart muscle. An eventual interaction between the antitumor effect of Adriamycin and the protective effect of selenium was ruled out by in vitro experiments using the L1210 cell line. Selenium did not abrogate the antiproliferative effect of Adriamycin when the cells were treated simultaneously with both agents. The results from this study indicate that Adriamycin-induced cardiotoxicity could be prevented by selenium if the animals were pretreated with selenium, rather than simultaneous administration of both agents. The mechanism of this effect is not entirely understood.

Animals↗
PubMed1985

[Studies on the behavior of mercury and selenium in blood of mice injected with those elements].

Male ddY mice were only once treated with, 1) mercuric chloride or methylmercuric chloride (20 mumol/kg, i.p., respectively) and various doses of sodium selenite (5, 20, and 40 mumol/kg, s.c., respectively) at the same time, 2) mercury compounds alone, and 3) various doses of sodium selenite alone. Then, the interaction between mercury and selenium was investigated in the blood and plasma at 1, 5, 24, 120, and 240 hr after injection. In mice receiving mercuric chloride and sodium selenite at the same time, the concentrations of mercury and selenium in the blood and plasma were markedly higher than those in mice receiving mercuric chloride or sodium selenite alone, especially at 1 and 5 hr after injection. In this case, mercury concentrations were increased depending on doses of sodium selenite. Furthermore, their decrement from 5 to 24 hr were markedly in groups with larger quantity of mercury accumulation. In the case of simultaneous injection of methylmercuric chloride and sodium selenite, the accumulation levels of mercury in the blood and plasma decreased by the simultaneous injection of selenium at 1 and 5 hr. The molar ratios of selenium to mercury in the blood and plasma simultaneously injected with mercuric chloride and sodium selenite were approx. 1 at 5 and 24 hr, independently of any change of sodium selenite doses. In gel filtration by Sephadex G-200 column of plasma of mice simultaneously injected mercuric chloride and sodium selenite, mercury reacted with selenium immediately after their injection, and the almost of them were bound and accumulated in the high-molecular weight fraction with the molar ratios (Se/Hg) of approx. 1 until about 24 hr after injection. After 24 hr of injection, however, the binding between mercury and selenium was significantly changed and their gel-filtration patterns were similar to those of each single dose group. These results suggested that mercury and selenium in the group of simultaneous injection of mercuric chloride and sodium selenite have different interaction in blood before and after 24 hr of injection.

Animals↗
PubMed1979

Effect of dietary selenium and vitamin E on the antioxiant defense systems of rat erythrocytes.

The effect of dietary selenium and vitamin E on the important cellular antioxidant defense systems was studied in rat erythrocytes. Weanling male Sprague-Dawley rats were fed a basal selenium and vitamin E deficient diet and supplemented with either none or 0.5 ppm selenium and either none or 45 ppm vitamin E for 35 or 40 days. Depletion of dietary selenium resulted in marked decrease of glutathione (GSH) peroxidase in the red cells, but the levels of GSH, catalase and superoxide dismutase were not significantly altered. The red cells of rats fed the basal diet deficient in both selenium and vitamin E had significantly lower levels of GSH and GSH peroxidase, but not of catalase and superoxide dismutase, than in those fed the basal diet and supplemented with either selenium, vitamin E or both. The results suggest that depletion of dietary selenium and vitamin may have a precipitate effect on lowering the levels of GSH and GSH peroxidase in rat erytyrocytes.

Animals↗
PubMed1984

Effects of selenium on polymorphonuclear leukocyte function in goats.

Polymorphonuclear neutrophils (PMN) from goats fed selenium-deficient and selenium-adequate diets were tested for their ability to perform (i) random migration under agarose, (ii) leukotaxis toward serum chemotaxins under agarose, and (iii) phagocytosis of opsonized zymosan by chemiluminescence analysis. Function of PMN from goats fed the selenium-deficient diet was severely depressed, and incubation of these cells with selenium resulted in marked functional enhancement. Also, administration of selenium to goats fed the selenium-deficient diet resulted in increased PMN functions. Increase or decrease in PMN function was associated with corresponding alterations in blood, serum, and intracytoplasmic PMN glutathione peroxidase activities. It was concluded that a selenium-inadequate diet fed to goats results in depressed PMN function which is associated with physiologic changes in glutathione peroxidase levels.

Animals↗
PubMed1983

Electrothermal atomic absorption spectrometric determination of selenium in foods and diets.

The validity of 2 electrothermal atomic absorption spectrometric methods for determination of selenium in foods and diets was tested. By using 0.5% Ni(II) as a matrix modifier to prevent selenium losses during the ashing step, it was shown that selenium can be determined in samples containing greater than or equal to 1 microgram Se/g dry wt without organic extraction. The mean recovery tested, using NBS Bovine Liver, was 98%; recovery of added inorganic selenium in Bovine Liver matrix was 100%. In addition, this method gave values closest to the median value of all participating laboratories using hydride generation AAS or the spectrofluorometric method in a collaborative study on high selenium wheat, flour, and toast samples. For samples with concentrations less than 1 microgram Se/g dry wt, separation of selenium from interfering Fe and P ions by organic extraction was necessary. Using inorganic 75Se in meat and human milk matrixes, an ammonium pyrrolidine dithiocarbamate-methyl isobutyl ketone-extraction system with added Cu(II) as a matrix modifier yielded the best extraction recoveries, 97 and 98%, respectively. Accuracy and precision of the method were tested using several official and unofficial biological standard materials. The mean accuracy was within 4% of the certified or best values of the standard materials and the day-to-day variation was 9%. The Se/Fe or Se/P interference limits proved to be low enough not to affect selenium determinations in practically all foods or diets. The practical detection limit of the method was 3 ng Se/g dry wt for 1.0 g dry wt samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1981

Factors influencing the anticarcinogenic efficacy of selenium in dimethylbenz[a]anthracene-induced mammary tumorigenesis in rats.

The present study was designed to investigate the effect of selenium supplementation on dimethylbenz[a]anthracene-induced mammary tumorigenesis in female Sprague-Dawley rats fed either a 5 or 25% corn oil diet, denoted as low fat (LF) or high fat (HF), respectively. Selenium supplementation of LF and HF diets were begun at 21 days of age. In Experiment 1, rats (50 days of age) were given 5 mg of dimethylbenz[a]-anthracene p.o. and were supplemented with 0.1 (adequate level), 0.5, 1.5, and 2.5 ppm of selenium (as sodium selenite) in the diet. The total number of tumors found were as follows (30 rats/group): 26, 23, 19, and 10, respectively, in the LF group; and 65, 66, 41, and 21, respectively, in the HF group. In experiment 2, rats (50 days of age) were given 10 mg of dimethylbenz[a]anthracene, and selenium was added to the diets at 0.1, 2,5, and 5.0 ppm. Tumor yields were found to be 71, 32, and 15, respectively, in the LF group and 135, 85, and 46, respectively, in the HF group. There was also a trend towards a longer latency period of tumor appearance with selenium supplementation. In conclusion, high dietary selenium levels are able to protect against mammary tumorigenesis, but rats on a HF diet still develop more tumors than those on a LF diet at comparable selenium supplementation.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1983

Astragalus bisulcatus--a cause of selenium or locoweed poisoning?

Certain plants accumulate selenium at levels that render them toxic. One of the principle groups of selenium-accumulating plants is the selenium-accumulating Astragalus. Reports in early literature suggest that selenium is the only toxin in these plants. Sheep fed Astragalus bisulcatus, a selenium-accumulating plant, had signs similar to those observed in locoweed poisoning, and the microscopic lesions from tissues collected from these sheep were similar to those of locoweed poisoning rather than selenium poisoning. This suggests this group of plants contains toxin compounds in addition to selenium.

Animals↗
PubMed1994

Selenium and lipid parameters in plasma of Portuguese subjects.

To obtain further insight into the role of selenium in the development of atherosclerosis, plasma selenium and lipid parameters were determined in 126 Portuguese subjects living in the region of Lisbon, 60 women and 66 men, 20-60 years old, divided up in to three groups according to their plasma lipid profile: Group I consisted of normolipidemic subjects having plasma triglycerides and total cholesterol < 200mg/dL; Group II was composed of hypercholesteremic subjects with total cholesterol > 200mg/dL and plasma triglycerides < 200mg/dL; Group III was composed of hypercholesteremic and hypertriglyceremic subjects having total cholesterol and plasma triglycerides > 200mg/dL. Respective values for mean plasma selenium (+/- SD) in the groups were: 93 +/- 18 micrograms/L, 90 +/- 17 micrograms/L and 96 +/- 18 micrograms/L. A weak significant difference in plasma selenium between women and men was, however, observed in Group I (87 +/- 20 micrograms/L vs. 100 +/- 11 micrograms/L, p < 0.05). Regression analysis showed no significant relationship between plasma selenium and lipid parameters, except in the most hyperlipidemic women of Group III, where a weak correlation between plasma selenium and the HDL-cholesterol/total cholesterol ratio (r = 0.80, p < 0.05) was observed. The present study suggests that the relationship between selenium and HDL-cholesterol has to be further examined, taking into account nutritional, metabolic and genetic factors.

Adult↗
PubMed1994

[Modulatory properties of selenium in immune processes].

Selenium, administered in various forms, is promoted as an immunostimulating agent. However, the relationship between selenium status of the organism and the immune system is particularly complex. Taking into account the results obtained from various animal models it is now difficult to find the site or sites of selenium action on the immune system. It is not known whether selenium exerts effect on all or only on selected stages of immune response. The survey of literature which includes in vast majority experiments on various animals, shows that selenium is an immunostimulating agent only under certain conditions and in adequate concentration. Further studies have to be performed before selenium in the form of selenium yeast or in another form is a recognized immunostimulator and could be accepted for medical practice.

Adjuvants, Immunologic↗