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PubMed1996

Lead, cadmium, mercury and selenium in Greenland marine animals.

Baseline concentrations of lead, cadmium, mercury and selenium are reported from different tissues in marine organisms from Greenland. Overall, lead levels in marine organisms from Greenland are low, whereas cadmium, mercury and selenium levels are high. Tissue differences are not very distinct for lead, whereas the opposite is the case for cadmium and mercury. Selenium shows an intermediate behaviour in this respect. In general, lead concentrations do not correlate with the age/size of animals, whereas cadmium, mercury and selenium increase with age/size of most species and tissues analysed. No clear conclusions can be drawn in relation to geographical differences in lead, mercury and selenium concentration in Greenland. In general, cadmium levels are higher in Northwest Greenland compared to southern areas. Local differences with increasing cadmium levels from inner fjords to the open sea in stationary species may be of the same order of magnitude as those observed over long distances in Greenland. There is no indication that lead and selenium levels increase in higher trophic levels, although this is clearly the case for cadmium and mercury. In almost all cases lead levels in marine organisms from Greenland are well below the Danish food standard limits, however, a substantial proportion of marine mammals and seabirds in Greenland have cadmium and mercury levels exceeding the Danish standard limits. No food standard limits are given for selenium in food, but in some cases human intake of selenium is estimated to be high.

Aging↗
PubMed1985

Toxicology of selenium in a freshwater reservoir: implications for environmental hazard evaluation and safety.

A study was conducted to document patterns of accumulation and toxicity of selenium to organisms in a power plant cooling reservoir in North Carolina. Selenium entered the reservoir by way of effluent from the coal ash disposal basin, which contained 100-200 micrograms Se/liter. Concentrations of selenium in the lake water averaged 10 micrograms/liter, but were accumulated from 519 times (periphyton) to 3975 times (visceral tissue, largemouth bass) in the biota. The pattern and degree of accumulation was essentially complete within 2 years after the initial operation of the power plant, and persisted throughout the remainder of the study: fishes greater than insects greater than annelids greater than molluscs greater than crustaceans greater than plankton greater than periphyton. The plantonic and detrital food pathways exposed fishes to potential dietary concentrations of selenium that were some 770 and 519-1395 times the waterborne exposure, respectively. Of the 20 species of fish originally present in the reservoir, 16 were entirely eliminated, 2 were rendered sterile but persisted as adults, 1 was eliminated but managed to recolonize from a relatively uncontaminated headwater area as sterile adults, and 1 was unaffected. Two nonnative fish species were accidentally introduced and established reproducing populations. Abundance and diversity of biota other than fishes was not affected. Relative to control habitats, the contaminated reservoir had concentrations of waterborne selenium that were 20-30 times background levels; the flora and fauna contained about 10-15 times background. The results show that selenium can accumulate and be biologically magnified to toxic levels in a reservoir even though waterborne concentrations are in the low microgram per liter range. This study also provides data which indicate that current toxicological information is neither accurate when used to predict the relative sensitivity of individual fish species to selenium, nor is it sufficient to predict community responses in a natural setting. It is very likely that long-term elevation of waterborne selenium to 8-10 micrograms/liter in warm-water lakes and reservoirs would result in biotic responses similar to those documented in this report.

Animals↗
PubMed1985

The effect of selenium deficiency in goats on lymphocyte production of leukocyte migration inhibitory factor.

The effect of dietary selenium on caprine leukocyte migration inhibitory factor (LMIF) production was examined in vitro using lymphocytes from goats fed a diet deficient in selenium. Selenium deficiency was determined by decreased plasma glutathione peroxidase (GSH-Px). The ability of peripheral blood lymphocytes to produce LMIF induced by concanavalin A (Con A) was significantly (P less than 0.05) inhibited when cells from selenium-deficient and selenium-adequate goats were compared. In contrast, no significant (P greater than 0.05) differences were found between lymphocytes from selenium-deficient and selenium-adequate goats for Interleukin-2 (IL-2) production and blastogenesis induced by Con A. These data suggest that selenium deficiency may selectively impair LMIF production and hence the ability of lymphocytes to modulate neutrophil migration.

Animals↗
PubMedDate not supplied

Selenium and lead: mutual detoxifying effects.

Antagonistic toxic effects of selenium and lead were studied in growing rats. Chronic lead intoxication was produced by cutaneous application of lead naphthenate solution (80-200 mg Pb/kg body weight) for a period of 8 weeks and chronic selenium intoxication was induced by giving 5 ppm, 10 ppm and 15 ppm selenium in drinking water. The growth rate and food consumption of rats receiving selenium in addition to lead approached normal rate while animals treated with only one of them showed hampered growth rate and lower food consumption. The enzymatic activity of delta-aminolevulinic acid dehydrase (ALA-D) in whole blood, liver and kidney and liver P-450 enzyme activity were normal in rats receiving both selenium and lead. The enzymic activities assayed were, however, depressed in the animals receiving either lead or selenium. Assay of lead and selenium in liver, brain, kidney and blood was carried out. Rats receiving both metals and higher concentrations of these metals in the organs studied, as compared to those only receiving one component. The data seem to indicate that the effect of selenium on the toxic effects of lead is similar to its protective role against methylmercury intoxication.

Animals↗
PubMed1981

Effect of selenium on azoxymethane-induced intestinal cancer in rats fed high fat diet.

The effects of selenium supplementation on azoxymethane-induced intestinal cancer were studied in male Sprague- Dawley rats given 8 weekly injections of azoxymethane (8 mg/kg body wt), and fed a 30% beef fat diet. Selenium-supplemented groups received 8 ppm H2SeO3 in drinking water. Blood selenium levels of supplemented rats increased rapidly the first 9 weeks of the experiment, followed by a plateau significantly higher than that for non-selenium controls. There was a significantly increase in liver and intestinal selenium levels in supplemented groups. The average number of intestinal tumors was 6.5 in the control group, and 3.1 in the selenium-supplemented group. There was a significant reduction in tumor incidence in the proximal half of the colon of selenium-treated rats. There was also increased concentration of tissue selenium in the proximal half of the colon of these rats.

Animals↗
PubMedDate not supplied

Uptake and localization of selenium-75 in mammary epithelial cell lines in vitro.

The uptake and subcellular localization of selenium-75 was examined in 3 established mammary cell lines in vitro. Previous studies had demonstrated that cell line YN-4 exhibited a biphasic growth response to selenium, whereas cell lines CL-S1 and WAZ-2t exhibited only an inhibition of growth. All 3 cell lines incorporated selenium-75 readily over a 48-h incubation period and the concentration of selenium-dependent glutathione peroxidase was correlated with the level of selenium-75 uptake. However, neither of these 2 parameters could be related to the unique biphasic growth response exhibited by cell line YN-4. The intracellular localization of selenium-75 was similar in lines CL-S1 and YN-4 with the label incorporated primarily in the cytosol and secondarily in the mitochondria. Although the unique growth response of line YN-4 could not be attributed to the incorporation parameters examined herein, the stable incorporation of selenium-75 at high levels should make these lines useful for further studies on the subcellular localization of selenium into organelles and macromolecules.

Animals↗
PubMed1984

Serum selenium and glutathione peroxidase, and plasma lipid peroxides in uterine, ovarian or vulvar cancer, and their responses to antioxidants in patients with ovarian cancer.

The concentrations of serum selenium and plasma lipid peroxides, and the activity of serum glutathione peroxidase (GSH-Px) were measured before any therapy in patients suffering from uterine, ovarian or vulvar cancer, and in association with 1-day combination cytotoxic chemotherapy of ovarian cancer following 1-week supplementation with selenium (96 micrograms/day), vitamin E (300 mg/day), selenium and vitamin E, or placebo. Patients with gynaecological cancer (N = 44) had lower serum concentration of selenium (1.15 +/- 0.04 S.E. mumol/l; P less than 0.05) and serum activity of GSH-Px (404 +/- 13 units/l, P less than 0.01) than the control subjects (N = 56; 1.25 +/- 0.03 mumol/l and 444 +/- 8 units/l, respectively). In association with cytotoxic chemotherapy selenium alone (P less than 0.05), vitamin E alone (P less than 0.05) and both of them together (P less than 0.001) decreased the plasma concentration of lipid peroxides, and the combination of selenium and vitamin E also increased the activity of serum GSH-Px (P less than 0.01). During placebo, cytotoxic chemotherapy did not affect plasma lipid peroxides but it decreased (P less than 0.001) the activity of GSH-Px. Selenium inhibited this effect. Our data suggest that antioxidative mechanisms of patients with gynaecological cancer may be defective and that treatment with selenium and vitamin E results in changes of biochemical factors related to lipid peroxidation.

Adult↗
PubMed1986

Serum and urinary selenium levels in thermal injury.

Information concerning selenium status in thermal injury patients is limited. Therefore, both serum selenium concentration and 24 h urinary excretion of selenium were evaluated throughout the hospital course for 23 patients with partial and full skin thickness thermal burns. Serum selenium levels were depressed throughout the hospital course in the majority of patients, and only two patients' serum selenium levels had reached the normal range by discharge. Urinary selenium losses were essentially within normal range throughout the same period and thus were not responsible for the observed depression in serum selenium levels. A possible antagonistic relationship between selenium and silver is discussed.

Adult↗
PubMed1985

Elemental selenium and glutathione reductase.

Selenium is an essential trace element important to several metabolic processes, although selenium in the chemical form of elemental selenium (Se degree) is commonly believed to be biologically inert. Recent data shows that colloidal suspensions of red amorphous elemental selenium are more easily reduced than previously thought, and that such reductions can potentially take place under biological conditions. The enzyme glutathione reductase, already known to be involved in selenium metabolism, is a good candidate to mediate the reduction of colloidal selenium to hydrogen selenide (H2Se), a compound of established biological activity. The implications of this hypothesis include the possibility that elemental selenium may be biologically active at least under some conditions, and that glutathione reductase may function in selenium metabolism primarily by maintaining the glutathione concentration in a reduced state.

Colloids↗
PubMedDate not supplied

Toxicity of selenium compounds to alveolar macrophages.

Selenium compounds released into urban atmospheres as a result of fossil fuel combustion may pose an inhalation hazard to people. Two chemical forms of selenium produced during coal combustion and present in combustion effluent are selenious acid. H2SeO3, and elemental selenium, Se. In an attempt to determine the toxicity of selenium compounds relative to other trace elements, the cytotoxicity of H2SeO3 and Se to rabbit alveolar macrophages in vitro was investigated. Macrophages were obtained by lung lavage and exposed in tissue culture after 20 h. Neither selenious acid nor elemental selenium caused cell lysis at concentrations which decreased total cell viability. Selenious acid was an order of magnitude more toxic then elemental selenium. Elemental selenium was similar in toxicity to environmental contaminants such as CdCl2 and V2O5. These in vitro cytotoxicity data can be used to predict the risk posed to people inhaling selenium compounds at levels found in urban atmospheres.

Animals↗
PubMed2004

Rapid induction of apoptosis in prostate cancer cells by selenium: reversal by metabolites of arachidonate 5-lipoxygenase.

Recent clinical trials have documented that selenium significantly reduces the incidence of clinical prostate cancer. However, nothing is clearly known about the underlying molecular mechanisms by which selenium exerts its anti-cancer effect. This report provides evidence that selenium at micro-molar concentrations induces rapid apoptotic death in human prostate cancer cells, but not in normal prostate epithelial cells. Apoptosis involves activation of caspase 3 which plays a critical role in the cell death process. Interestingly, the apoptosis-inducing effect of selenium in prostate cancer cells is substantially alleviated by the 5-lipoxygenase metabolites, 5(S)-HETE and its dehydrogenated derivative 5-oxoETE, but not by metabolites of 12-lipoxygenase (12(S)-HETE) or 15-lipoxygenase (15(S)-HETE). Apoptosis is also prevented by their precursor, arachidonic acid, an omega-6, polyunsaturated fatty acid, presumably by metabolic conversion through the 5-lipoxygenase pathway. These results indicate that selenium's anticancer effect may involve induction of apoptosis specifically in prostate cancer cells sparing normal prostate epithelial cells, and that 5-lipoxygenase may be a molecular target of selenium's anticancer action. The present report warrants that care should be taken about high intake of dietary fat containing arachidonic acid or its precursor fatty acids when selenium is used for the management of prostate cancer, and suggests that a combination of selenium and 5-lipoxygenase inhibitors may be a more effective regimen for prostate cancer control.

Apoptosis↗
PubMed2005

Impact of selenium on mood and quality of life: a randomized, controlled trial.

BACKGROUND: Selenium is known to be important to the brain. Three small, published studies have suggested an effect of selenium supplementation or deprivation on mood in healthy volunteers. We investigated these findings on a much larger scale. METHODS: In this double-blind, placebo-controlled intervention, 501 UK participants aged 60-74 were randomly allocated to receive 100, 200 or 300 microg selenium/d as high-selenium yeast or placebo yeast. Mood (Profile of Moods States - Bipolar Form [POMS-BI] questionnaire), "quality of life" (Short Form 36 [SF-36] questionnaire) and plasma selenium were measured at baseline and six months. RESULTS: Supplementation significantly increased plasma selenium above baseline values: from an overall mean (SD) of 90(19) ng/g to 91(26), 144(27), 191(41) and 227(53) ng/g in the placebo, 100, 200, 300 microg selenium groups respectively (p < .001). Four hundred forty-eight participants completed the POMS-BI questionnaires at both time points, with no significant differences in total mood or mood-subscale scores seen between doses. After six months of supplementation, mean (SD) total mood scores for the four doses were 163(36), 161(37), 162(33), 162(34), F(3,443) = .25, p = .86. Quality of life was similarly unaffected. CONCLUSIONS: There was no evidence that selenium supplementation benefited mood or quality of life in these elderly volunteers. Though this is at odds with some previous results, our robust study design, much larger sample size and longer supplementation period, together with the evidence that the brain is a privileged site for selenium retention, suggest that this is a reliable finding.

Affect↗
PubMed2006

Selenium and vitamins status in Saudi children.

BACKGROUND: Selenium is an essential element, and a cofactor required to maintain glutathione peroxidase activity. Its deficiency may induce modification in the cellular antioxidative status and the appearance of different diseases. Previous studies in Al-Kharj reported low selenium levels in the soil and the milk of lactating mothers living in that area. METHODS: A cross-sectional study was carried out to determine the status of selenium, dl-alpha-tocopherol, and all-trans-retinol in 513 Saudi children living in Al-Kharj district using serum and toenail samples. RESULTS: The prevalence of children with serum selenium below the threshold limit of clinical importance in coronary and cardiovascular diseases (45 microg/l) was only 1.4%, while 53.4% of the tested children had toenail selenium >0.56 microg/g, which is considered a low level as indicated in a previous study. DL-alpha-tocopherol deficiency (<0.5 mg/dl) was found only in 3.1%. However, none of the children in this study had a severe all-trans-retinol deficiency (<10 microg/dl) and the percentage of children with marginal deficiency <20 microg/dl was 5.5%. CONCLUSION: It seems that the geographical location of primary health care units (PHCUs) is the most important factor in influencing the selenium status of these children. This implies variations in food habits. Serum and toenail selenium concentrations were significantly related which can both reflect dietary selenium intake. Although our results suggest an adequate vitamin A status, we found interestingly that 10.9% of the children had retinol >50 microg/dl. This suggests that a high dietary intake of vitamin A might have a harmful effect. Further work is necessary to determine whether the hypervitaminosis A in children reflects an excessive dietary intake of retinol. A significant negative association was also found between dl-alpha-tocopherol and all-trans-retinol and malonaldehyde (MDA) levels in the serum of children population. This confirms their role in reducing oxidative stress.

Adolescent↗
PubMed2006

Selenium speciation analysis using inductively coupled plasma-mass spectrometry.

Selenium exists in several oxidation states and a variety of inorganic and organic compounds, and the chemistry of selenium is complex in both the environment and living systems. Selenium is an essential element at trace levels and toxic at greater levels. Interest in speciation analysis for selenium has grown rapidly in this last decade, especially in the use of chromatographic separation coupled with inductively coupled plasma-mass spectrometry (ICP-MS). Complete characterization of selenium compounds is necessary to understand selenium's significance in metabolic processes, clinical chemistry, biology, toxicology, nutrition and the environment. This review describes some of the essential background of selenium, and more importantly, some of the currently used separation methodologies, both chromatographic and electrophoretic, with emphasis on applications of selenium speciation analysis using ICP-MS detection.

Chromatography, Gas↗
PubMed2005

Selenium impacts on razorback sucker, Colorado: Colorado River III. Larvae.

Razorback sucker (Xyrauchen texanus) larvae from adults exposed to selenium at three sites near Grand Junction, Colorado, for 9 months were used in a 30-day waterborne and dietary selenium study. Selenium concentrations in water averaged <1.6 microg/L from 24-Road, 0.9 microg/L from Horsethief, 5.5 microg/L from Adobe Creek, and 10.7 microg/L from the North Pond. Selenium in dietary items averaged 2.7 microg/g in brine shrimp, 5.6 microg/g in zooplankton from Horsethief east wetland, 20 microg/g in zooplankton from Adobe Creek, and 39 microg/g in zooplankton from North Pond. The lowest survival occurred in larvae fed zooplankton rather than brine shrimp. Survival of larvae at Adobe Creek and North Pond was lower in site water than in reference water. Survival of brood stock larvae was higher than Horsethief larvae even though they received the same water and dietary treatments. Arsenic concentrations in brine shrimp may have resulted in an antagonistic interaction with selenium and reduced adverse effects in larvae. Deformities in larvae from North Pond were similar to those reported for selenium-induced teratogenic deformities in other fish species. Selenium concentrations of 4.6 microg/g in food resulted in rapid mortality of larvae from Horsethief, Adobe Creek, and North Pond, and suggested that selenium toxicity in the Colorado River could limit recovery of this endangered fish.

Abnormalities, Drug-Induced↗
PubMed2005

Mercury and selenium concentrations in fish samples from Cachoeira do PiriáMunicipality, ParáState, Brazil.

Mercury is a major public health concern because of its widespread occurrence in the environment and its toxic effects on humans, mainly through fish ingestion. On the other hand, selenium is known by its antioxidant effect. For this reason, the knowledge of the correlation between mercury and selenium concentrations in fish samples can bring important information allowing a better understanding of mercury equilibrium in the inhabitants of the Amazon region. In this paper, total mercury and selenium levels were measured in carnivorous (47), omnivorous (44), and herbivorous (4) fish species caught in rivers and in an artificial lake in Cachoeira do PiriáMunicipality, situated in ParáState, Amazon region. The mercury concentration ranged from 1.15 to 13.44 nmol g(-1) and selenium from 2.44 to 14.56 nmol g(-1) for carnivorous species. For noncarnivorous species, mercury concentration ranged from 0.08 to 2.03 nmol g(-1) and selenium from 1.27 to 15.32 nmol g(-1). The molar ratios between mercury and selenium contents obtained for carnivorous and noncarnivorous species were 0.65 and 0.14, respectively. Mercury and selenium levels were positively correlated with fish body mass (weight) only for Hoplias malabaricus (n=35, R2=0.565, P<0.005 and R2=0.608, P<0.005, respectively). Selenium and mercury concentrations were statistically positively correlated only for H. malabaricus (n=35, R2=0.787, P=0.005) and Leporinus sp. (n=38, R2=0.485, P<0.005) known locally as Traíra (carnivorous) and Aracu (omnivorous), respectively.

Animals↗
PubMed2000

Speciation of selenium compounds with ion-pair reversed-phase liquid chromatography using inductively coupled plasma mass spectrometry as element-specific detection.

For selenium speciation analysis, the hyphenation of chromatographic separation with element-specific detection has proved a useful technique. A powerful separation system, which is capable of resolving several biologically and environmentally important selenium compounds in a single column, is greatly needed. However, that has been difficult to achieve. In this paper eight selenium compounds, namely, selenite [Se(IV)], selenate [Se(VI)], selenocystine (SeCys), selenourea (SeUr), selenomethionine (SeMet), selenoethionine (SeEt), selenocystamine (SeCM) and trimethylselenonium ion (TMSe+), were separated by using mixed ion-pair reagents containing 2.5 mM sodium 1-butanesulfonate and 8 mM tetramethylammonium hydroxide as a mobile phase. The separation of these anionic, cationic and neutral organic selenium compounds on a LiChrosorb RP18 reversed-phase column took only 18 min at a flow-rate of 1.0 ml/min with isocratic elution, and baseline separation among the six organic Se compounds was achieved. Inductively coupled plasma mass spectrometry (ICP-MS) was employed as element-specific detection. A comparison of ICP-MS signal intensity obtained with a Barbington-type nebulizer and with an ultrasonic nebulizer (USN) was made. Different signal enhancement factors were observed for the various selenium compounds when a USN was used. The speciation technique was successfully applied to the study on chemical forms of selenium in a selenium nutritional supplement. Selenomethionine was found to be the predominant constituent of selenium in the supplement.

Chromatography, High Pressure Liquid↗
PubMed1987

Macrocytosis and pseudoalbinism: manifestations of selenium deficiency.

Selenium levels were low in four children receiving long-term total parenteral nutrition (TPN) who developed erythrocyte macrocytosis (3/4), loss of pigmentation of hair and skin (2/4), elevated transaminase and creatine kinase activities (2/4), and profound muscle weakness (1/4). Initial mean selenium levels in serum and hair were 38 +/- 11 (SEM) ng/mL and 0.34 +/- 0.13 micrograms/g, respectively. Mean serum vitamin B12, folate, and vitamin E levels were normal. Intravenous supplementation with selenium was begun daily at 2 micrograms/kg/day. After 3 to 6 months, serum selenium levels rose almost threefold to 81 +/- 22 ng/mL. During this same time, erythrocyte mean corpuscular volume fell from 115 +/- 8 fL to 88 +/- 7 fL in the three children with macrocytosis. After 6 to 12 months of supplementation, hair selenium content had increased threefold to 1.02 +/- 0.19 micrograms/g. The two children with decreased pigmentation became darker skinned and their hair color changed from blonde to dark brown; a third child's hair, which had been blonde, also became darker. Transaminase and creatine kinase activities returned to near normal in those affected and, in the one child with severe myopathy, muscle weakness improved. Erythrocyte macrocytosis and loss of skin and hair pigmentation are previously undescribed manifestations of selenium deficiency. We recommend routine supplementation of TPN solution with selenium to avoid the clinical and biochemical syndrome of selenium deficiency in patients receiving long-term TPN.

Alanine Transaminase↗