Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Selenium”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,513 records · Page 84Linked to original sources
PubMed1994

[Selenium supplementation with bread].

Bread produced with selenium-enriched yeast was given to ten volunteers. The daily dose contained approximately 100 micrograms of selenium. The subjects' mean baseline whole blood selenium concentration (52.2 +/- 16.7 micrograms/l) was indicative of a suboptimal selenium status. After two weeks of supplementation, the subjects' mean whole blood selenium level increased significantly (to 66.1 +/- 11.9 micrograms/l). Supplementation of selenium-enriched bread seems to be an easily implementable and promptly acting method of selenium status improvement.

Adult↗
PubMed1993

Effects of different levels of dietary selenium and vitamin E on the humoral immunity of rats.

The aim of the present study was to investigate whether the level of selenium and selenium/vitamin E supply influences the humoral immunity of rats. In order to detect the effect of Se supply and age, 36 weaned Sprague-Dawley rats divided into two equal groups were killed after 22 or 45 experimental days by decapitation (Exp. I). In Exp. II 9 groups of 10 rats each were exposed to each combination of deficient, normal or excessive selenium with a vitamin E supply and killed after 44 days. The basic (deficiency) diet which was the same in both experiments contained 0.04mg Se and 8mg vitamin E per kg dry matter. The supplementation per kg diet was 0 or 0.2mg Se and 30mg vitamin E in Exp. I and 0, 0.2 or 1mg Se and 0, 30 or 200mg vitamin E in Exp. II. The concentration of selenium in serum, liver and spleen samples and the activity of glutathione peroxidase, which were determined to define the selenium status of the animals, corresponded well to the required supply situation. The immunoglobulins of type IgA, IgM and IgG with the subtypes IgG1, IgG2a, IgG2b and IgG2c were measured by immunoelectrophoresis. In both experiments selenium deficiency decreased the values of the IgG groups only nominally, IgA was not changed. IgM was significantly reduced, especially with prolonged selenium deficiency and simultaneous vitamin E deficiency. An excessive selenium supply compensated to a great extent for the effects of vitamin E deficiency on IgG and IgA.

Animals↗
PubMedDate not supplied

Plasma, erythrocyte and urinary selenium levels in sickle cell homozygotes and traits.

Plasma, erythrocyte and urinary selenium levels were determined in 21 sickle cell homozygote patients, 20 siblings with sickle cell traits, 29 parents and in 21 healthy controls with an HbAA pattern. The mean levels of plasma and erythrocyte selenium and the daily urinary selenium depletion were found to be lower in the HbSS patients than in the controls (p < 0.02; p < 0.001; p < 0.001, respectively). Urinary selenium depletion was found to be lower in the sickle cell trait siblings than in the controls (p < 0.001), but the plasma and erythrocyte selenium levels were close to normal values (p > 0.05). The mean erythrocyte selenium levels were found to be decreased in the parents as compared with the controls (p < 0.05), which indicates that urinary selenium losses may be replenished primarily by sources in the plasma and in the erythrocytes before stores in the other parts of the body are used.

Adolescent↗
PubMed1993

Urinary selenium concentrations.

Urinary selenium concentrations are used as an indicator of selenium status. A strong correlation has been established between dietary selenium and daily urinary selenium excretion in a wide range of populations from all over the world with different dietary selenium intake. Data on urinary selenium concentrations in healthy individuals and patients with different pathological conditions are reviewed. Selenium excretion rates of 20-200 micrograms/day are not associated with deficiency or toxicity problems. Urinary Se excretion is decreased in children, elderly people, and pregnant women. Workers exposed to heavy metals, and cancer patients, have higher and lower urinary Se concentrations, respectively, than control groups. The trimethylselenonium ion, a minor metabolite of Se in urine, assumes a significant role only in the detoxification of excess Se intake. Studies of bioavailability and balance show the important role of the kidneys in homeostatic regulation of Se.

Humans↗
PubMed1993

[Selenium metabolism and glutathione peroxidase activity of endurance athletes in rest and under exertion].

Selenium which has been recognised as an essential trace element for mammals and humans is part of the enzyme glutathione peroxidase (GSHPx) and of other selenium-dependent enzymes. GSHPx protects the organism from oxidative damage. Supposing that the formation of peroxides is enhanced in athletes during a marathon run the question arose whether the selenium concentrations in the blood plasma and the GSHPx activities in the erythrocytes are changed. Our experiments were performed with 13 athletes completing a marathon. Blood probes were taken before, immediately after and two hours after the endurance event. No significant changes in the selenium concentrations of the blood plasma probes nor of the enzyme glutathione peroxidase activities of the erythrocytes were observed during the experiments. The selenium concentrations in the plasma: 77.7 +/- 20.8 micrograms/l and the GSHPx activities of the erythrocytes 18.2 +/- 7.4 U/g Hb were within normal clinical range. Symptoms of selenium deficiency could not be detected. In order to answer the question of whether the selenium concentrations in the blood of the athletes represent an optimal level for preventing enhanced formation of peroxides, intervention studies are needed, including measurement of more parameters of lipid peroxidation.

Adult↗
PubMed1995

Studies on human dietary requirements and safe range of dietary intakes of selenium in China and their application in the prevention of related endemic diseases.

The human dietary selenium requirement in China has been estimated by various methods. The minimum dietary selenium requirement for the prevention of Keshan disease (KD) was found to be around 17 micrograms/d. On the other hand, an intake of 40 micrograms/d is required to maintain the plasma glutathione peroxidase (GPx) activity at plateau. Hence 40 micrograms/d is considered as the adequate dietary selenium requirement. Studies conducted in a chronic selenosis area indicate that the toxic dietary selenium intake (adverse effect level), which would maintain the characteristic fingernail changes, was approximately 1600 micrograms/d. The mean value of dietary selenium intakes, which enabled the five patients to recover from fingernail lesions, was found to be 819 +/- 126 micrograms/d. At a 95% confidence limit, the lower limit is around 600 micrograms/d. Therefore, 600 and 400 micrograms/d were suggested as the individual daily maximum safe selenium intake and the safe dietary selenium intake, respectively. The results were used in the prevention of Se-related endemic KD and Kashin-Beck disease (KBD).

Cardiomyopathy, Dilated↗
PubMedDate not supplied

Selenium and glutathione peroxidase levels in healthy infants and children in Austria and the influence of nutrition regimens on these levels.

Serum selenium values were investigated in 56 formula-fed and in 18 wholly breast-fed infants. In 14 of these infants, glutathione peroxidase (GSH-Px) was also investigated. Determination of selenium and GSH-Px was also done in umbilical cord blood of seven healthy newborns. In another 109 infants aged 1-15 yr, serum selenium values were investigated. A continuous fall of serum selenium values was noted in the first 3 mo of life. Low levels continued until the age of 6 mo with a mean of 36% of the umbilical cord vein level. Breast-fed babies of GSH-Px showed a less pronounced fall in selenium and had significantly higher levels of GSH-Px. GSH-Px activity was reduced from age 5 to 8 mo. Feeding of beikost caused a rise in the level of selenium. Children in the age groups 1-15 yr still had a significantly lower serum selenium level than adults.

Adolescent↗
PubMed1996

[Selenium deficiency associated with cardiac dysfunction in three patients with chronic respiratory failure].

We encountered three patients with chronic respiratory failure who had heart failure of cardiac arrhythmias and low levels of serum selenium. All three had tracheostomies and had received long-term parenteral nutrition that had not included selenium. All three also had refractory cardiac dysfunction, which was manifested in edema, heart failure, and various tachycardias. We suspected that selenium deficiency had caused their cardiac dysfunction. Serum selenium concentrations were found to be much lower than normal in all three, so 100 micrograms/day of selenium was administered in addition to their tube feedings. Cardiac function improved after replacement of selenium. These cases show the need for preventing selenium deficiency in patients with chronic respiratory failure during long-term administration of parenteral nutrition.

Aged↗
PubMedDate not supplied

The inhibitory effect of selenium on induction of tetraploidy by dimethylarsinic acid in Chinese hamster cells.

Arsenic is a human carcinogen. On the other hand, selenium supplementation can inhibit induction of carcinogenesis by chemical carcinogens. The effect of selenium compounds on the cytotoxicity of dimethylarsinic acid (DMA) and on the induction of tetraploidy by DMA were studied using Chinese hamster V79 cells. Two selenium compounds were tested, sodium selenite and trimethylselenonium iodide (TMSeI). Trimethylselenonium is a major excretory product of selenite metabolism. The cytotoxicity of sodium selenite was 1000-fold greater than that of TMSeI. The cytotoxicity of DMA was about the same as that of TMSeI. The mitotic index for DMA administration was increased by these selenium compounds at low concentrations and decreased by them at high concentrations. The tetraploid index for DMA decreased with increasing concentrations of these selenium compounds. Tetraploidy is a form of aneuploidy, and aneuploidy is known to induce carcinogenesis. The finding that selenium inhibited induction of tetraploidy by DMA may yield clues to the role of selenium in the chemoprevention of carcinogenesis by chemical carcinogens.

Aneuploidy↗
PubMed1997

Selenium and cardiovascular diseases--an update.

Dietary deficiency of selenium has been incriminated in the etiology of cardiovascular diseases. Thus, cardiomyopathy associated with low selenium intake has been described in areas of exceptionally low selenium intake and in patients receiving total parenteral nutrition. Epidemiological studies have provided some evidence for the role of selenium deficiency in the etiology of atherosclerotic disease. An inverse association between the incidence of ischaemic heart disease and selenium intake has been described in population comparisons. The results of longitudinal studies within populations are conflicting. While some investigations have observed a relationship between low serum-selenium levels and the risk of coronary disease, others have not. Final evidence for the role of selenium in preventing atherosclerotic disease can be obtained only from controlled prevention trials.

Animals↗
PubMed1997

[Blood selenium content after conditioning and during the course of bone marrow transplantation in children with malignant diseases].

PATIENTS AND RESULTS: Prior to bone marrow transplantation (BMT), at the end of the conditioning phase, we found in 42 investigated children with malignant diseases subnormal lowered plasma- and blood selenium levels. Parallel to the diminished selenium status the plasma glutathione peroxidase activity (Gpx) was not reduced as it is in selenium deficiency, but markedly elevated and probably reflecting cytolytic processes. In the group of combined conditioning (fractionated total body irradiation plus chemotherapy) we found significantly more elevated plasma Gpx values in comparison to the only-chemotherapy group. The renal selenium excretion was elevated during the whole observation and could be caused by disturbed tubular function. CONCLUSION: We conclude, that in the situation of BMT a selenium substitution in a dosage of at least 1 to 2 micrograms Se/kg/d is necessary. Patients' selenium status should be monitored by analyses of plasma- and blood selenium contents.

Adolescent↗
PubMed1997

Environmental implications of excessive selenium: a review.

Selenium is a naturally occurring trace element that is nutritionally required in small amounts but it can become toxic at concentrations only twice those required. The narrow margin between beneficial and harmful levels has important implications for human activities that increase the amount of selenium in the environment. Two of these activities, disposal of fossil fuel wastes and agricultural irrigation of arid, seleniferous soils, have poisoned fish and wildlife, and threatened public health at several locations in the United States. Research studies of these episodes have generated a data base that clearly illustrates the environmental hazard of excessive selenium. It is strongly bioaccumulated by aquatic organisms and even slight increases in waterborne concentrations can quickly result in toxic effects such as deformed embryos and reproductive failure in wildlife. The selenium data base has been very beneficial in developing hazard assessment procedures and establishing environmentally sound water quality criteria. The two faces of selenium, required nutrient and potent toxin, make it a particularly important trace element in the health of both animals and man. Because of this paradox, environmental selenium in relation to agriculture, fisheries, and wildlife will continue to raise important land and water management issues for decades to come. If these issues are dealt with using prudence and the available environmental selenium data base, adverse impacts to natural resources and public health can be avoided.

Animals↗
PubMed1998

Serum selenium in the general population of Singapore, 1993 to 1995.

Selenium is a trace element which plays a vital role in many metabolic functions and in particular is an integral part of the antioxidant enzyme glutathione peroxidase. It may be involved in the prevention of a number of diseases including cardiovascular diseases and cancer, which are the main causes of death in Singapore with ethnic differences. The National University of Singapore Heart Study measured cardiovascular risk factors, including serum selenium, in a random of the general population aged 30 to 69 years from 1993 to 1995. Mean serum selenium was higher in Chinese (males 126 and females 119 micrograms/L) and Malays (males 122 and females 122 micrograms/L) than Indians (males 117 and females 115 micrograms/L). These levels (with an estimated mean of 122 micrograms/L in Singapore) are lower than those in the USA but higher than those in Western Europe. The proportions with serum selenium < 80 micrograms/L (classified as low values) were low, though highest in Indians (males 1.2% and females 1.2%), then Chinese (males 0.6% and females 1.3%) and then Malays (males 0.0% and females 0.0%), but the differences were not statistically significant. The overall estimate for the prevalence of low selenium in Singapore was 0.8%. It is concluded that levels of serum selenium in Singapore are satisfactory and no action with regard to dietary supplementation is needed. Serum selenium levels are slightly lower in Indians than in Chinese and Malays (probably due to a more vegetarian diet) and this may make a small contribution to Indians' higher rates of coronary heart disease compared to Chinese and Malays.

Adult↗
PubMed1998

[Serum selenium levels in the population of four regions in southern Moravia].

The paper deals with the problem of selenium in the food chain of man. The authors investigated the serum selenium concentration of healthy blood donors in four South Moravian regions. Consistent with other authors they found a marked deficiency of this element. While optimal values in analyzed samples were found in 11% in the Trebíc area, 5% in the Vyskov and Brno area, in the Znojmo area no specimens belonging in that group were found. Based on the assembled results the authors consider 22% of the South Moravian population selenium deficient. With regard to this finding it would be useful to modify the therapeutic pattern in some serious conditions. The question remains what to do for the general population. There are several possibilities: adding selenium to fertilizer leading to higher contents in food, administration of selenium preparations, mixing agricultural products containing high and low selenium concentration and finally complete knowledge of selenium metabolism.

Adolescent↗
PubMed1976

[The effect of selenium and fluorine with respect to caries and toxicity to Osborne-Mendel-rats (author's transl)].

Two experiments carried out with one hundred rats from the Osborne-Mendel-strain were supposed to prove the influence of selenium-containing-drinking-water on caries. The animals were divided into five experimental groups of twenty rats each. Selenium was tested in different doses as an addition to drinking-water in shape of Na2SeO4, as well as in combination with a tooth-paste containing NaF.-Its toxicity was to be determined by the water consumption, the mortality and above all by the body weight of the animals at the end of the test. During the first experiment three groups received Na2SeO4 in doses of 1, 5 and 10 ppm in the drinking water and the cariogenic diet Stephan 580 as food. Two other groups served as control, one receiving the cariogenic diet Stephan 580 and the other one getting the normal breeding diet. The analysis of variance carried out for the assessment of caries and the test of SCHEFFE only show a different attack concerning those groups, receiving the cariogenic diet and the control group fed with the breeding diet Altromin R. Nine of the 40 animals of the groups that had received the selenium doses of 5 and 10 ppm did not survive the experiment. The average value of the water consumption and the body weight of the animals of the selenium group was below the average of the remaining groups, which points out a strong toxicity of Na2SeO4. In regard to the water consumptions, however, one cannot exactly define, whether it is an effect of the selenium of the cariogenic diet. All groups of the second experiment received the cariogenic diet Stephan 580; two of them got Na2SeO4 in doses of 4ppm within their drinking water. The molars of the lower jaws of one of these group were brushed with a tooth-paste containing NaF. The molars of the other group were treated with a paste, serving as a placebo. Two other groups were provided each with the paste containing fluorine and the paste serving as a placebo, but without selenium in their drinking water. Furthermore 20 animals were used as a control group. The analysis of variance showed the widely known protective effect of the fluorine by the statistically significant different distribution of the caries. Comparing those two groups, whose drinking water contained Na2SeO4 with the two other groups whose molars were treated with the paste containing fluorine and the one serving as a placebo respectively, we may conclude, that Na2SeO4 has no influence on the protective effect of the fluorine. A comparison of the group treated with the paste serving as a placebo with the control group shows, that the tooth-brushing obviously has no great effect. In respect to the body weight at the end of the experiment one cannot demonstrate a clear effect using the linear contrast of SCHEFFE, and there also is no infleunce of selenium on the total water consumption, which coincides with the results of the first experiment. The two experiments have shown that Na2SeO4 is toxic in the doses applied...

Animals↗
PubMed1997

[Selenium administration in sepsis patients].

BACKGROUND: It has been hypothesized that low serum selenium concentrations, associated with low glutathione peroxidase activities in critical ill patients may contribute to decreased cleavage from free radicals and deteriorate the clinical outcome. PATIENTS AND METHODS: We therefore performed a controlled, prospective study including 42 patients with inflammatory response syndrome and an APACHE-II score > or = 15. Whereas the controls (Se-, n = 21) received 35 micrograms sodium selenite during the whole treatment period the selenium substitution group (Se+, n = 21) received additional 500 micrograms, 250 micrograms and 125 micrograms sodium selenite, each amount for 3 days. Clinical outcome was monitored by APACHE-III score, documentation of acute renal failure, respiratory insufficiency and the mortality rate until discharge from the hospital. RESULTS: The mean APACHE-II(III) score on admission was 20.6 (68.3) in the Se- versus 20.1 (61.0) in the Se+ group. Age, sex, underlying diseases, the serum selenium levels and glutathione peroxidase activities on admission were equally distributed in both groups. Selenium substitution was followed by a significant increase in serum selenium levels and glutathione peroxidase activity to normal levels, whereas in controls both parameters remained low. The APACHE-III score significantly improved on day 7 (p = 0.018) and 14 (p = 0.041) in the Se+ group. Hemodialysis because of acute renal failure was necessary in 9 (Se-) versus 3 (Se +) patients (p < 0.04). Overall mortality rate in the Se+ group was 33.5% versus 55% in the Se- group (p = 0.13). A subanalysis of those patients with an APACHE-II score > 20 (n = 10) in each group revealed a significant reduction in mortality from 70% to 30% (p = 0.013). No negative side effects of selenium were seen. CONCLUSION: Selenium substitution significantly improves clinical outcome and reduces the incidence of acute renal failure.

APACHE↗
PubMed1993

Reproduction of mallards following overwinter exposure to selenium.

Forty pairs of mallards (Anas platyrhynchos) were fed 15 ppm selenium as selenomethionine for about 21 weeks during winter. Twenty pairs served as controls. At the end of 21 weeks, which coincided with the onset of the reproductive season, selenium treatment was ended. Four birds died while on selenium treatment. Treated females lost weight, and their egg-laying was delayed. Hatching success of some of the first eggs laid by selenium-treated females was lower than that of controls, and a few of these early eggs contained deformed embryos, but, after a period of about two weeks off the selenium-treated diet, reproductive success returned to a level comparable with that of controls. The return to normal reproductive success was the result of a corresponding decrease in selenium concentrations in eggs once selenium treatment ended.

Journal Article↗
PubMed2000

Factors affecting soluble selenium removal by a selenate-reducing bacterium Bacillus sp. SF-1.

High concentrations of soluble selenium, selenate and selenite, have acute and chronic toxicity toward living things. With the aim of developing a biological process for selenium removal, the effects of a variety of parameters on the reduction of soluble selenium by a Bacillus sp. strain SF-1, which is capable of reductively transforming selenate into selenite and, subsequently, into nontoxic insoluble elemental selenium, were studied. The bacterial strain could effectively reduce 20 mM of selenate to selenite and 2 mM of selenite to elemental selenium in the presence of an appropriate carbon source and in the absence of oxygen. The reduction rate of selenate to selenite was much higher than that of selenite to elemental selenium, resulting in the transient accumulation of selenite during selenate reduction. The selenate reduction rate increased with increases in the selenate concentration up to 20 mM, while the rate of selenite reduction decreased sharply at selenite concentrations of more than 2 mM. The elemental selenium transformed from selenate via selenite was found both inside and outside the cells. Bacillus sp. SF-1 was able to utilize a variety of organic acids or sugars as a carbon source in selenate reduction. Although the copresence of sulfate did not inhibit selenate reduction, it was completely inhibited by some other oxyanions, including nitrate. A model sequencing batch system using the bacterial strain was developed and exhibited good performance in the treatment of wastewater containing high concentrations of selenate.

Journal Article↗