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PubMed2006

Selenium is inversely associated with bladder cancer risk: a report from the Belgian case-control study on bladder cancer.

AIM: Selenium is an essential trace element with suspected anticarcinogenic properties in humans. To date, eight epidemiological studies have examined the association between serum selenium concentration and bladder cancer risk. METHODS: The authors carried out a population case-control study in 178 cases and 362 controls to assess the relationship between bladder cancer risk and selenium serum concentrations. Unconditional logistic regression was calculated to determine odds ratios (OR) for bladder cancer occurrence with corresponding 95% confidence intervals (95% CI). Effect modification by smoking status, low fruit and vegetable intake, retinol equivalent, vitamin C, vitamin E and total antioxidant status were also assessed. RESULTS: Serum selenium level was negatively associated with bladder cancer risk. After adjustment for sex, age, smoking and occupational exposure, the OR was 0.48 (95% CI 0.29-0.79) comparing the second with the lowest tertile (serum selenium concentration >82.40 microg/L). The adjusted OR for the highest tertile (serum selenium concentration >96.00 microg/L), was 0.30 (95% CI 0.17-0.52) (P-trend <0.001). An increase of 10 microg/L in serum selenium concentration was associated with a significant decreased bladder cancer risk (OR: 0.76; 95% CI 0.67-0.85). CONCLUSION: This case-control study suggests an inverse association between serum selenium concentration and bladder cancer risk.

Aged↗
PubMed1993

Selenium and oxygen-metabolizing enzymes in elderly community residents: a pilot epidemiological study.

OBJECTIVE: To investigate the relationship of selenium and oxygen-deactivating enzymes with age in the elderly. SAMPLE: The study sample consisted of volunteers recruited from the PAQUID study. This study is conducted in a representative sample of non-institutionalized individuals aged > or = 65 years living in Southwestern France; its main objective is to study longitudinally the incidence and risk factors of dementia. METHODS: Plasma and erythrocyte selenium and activities of oxygen metabolizing enzymes in erythrocytes (GSH-Px, CuZn-SOD, and GSSG-RD) were measured in 239 volunteers (108 males and 131 females; mean age 73.7 years). RESULTS: Plasma selenium (PSe) decreased significantly with age; a similar but non-significant trend was found for erythrocyte selenium (ESe). None of the enzyme activities showed a clear relationship with age. Women had significantly higher GSH-Px activities than men. For PSe levels lower than 77 ng/mL, there was a strong correlation between PSe and GSH-Px; above this value, the correlation decreased, suggesting that the selenium requirement for GSH-Px production had been satisfied. In this sample, CuZn-SOD was correlated negatively with GSH-Px (r = -0.18; P < or = 0.01) and positively with GSSG-RD (r = +0.20; P < or = 0.01). CONCLUSIONS: In individuals aged > or = 65 years, we found that blood selenium levels were negatively correlated with age. Our analysis of the relationship between selenium and GSH-Px activity suggests that low selenium values are associated with decreased GSH-Px activity.

Aged↗
PubMed1988

Correlation between plasma levels of selenium and antithrombin-III.

Patients with previous myocardial infarction were tested for antithrombin-III (AT-III) activity and selenium levels in their plasma and compared with sex- and age-matched healthy control individuals. Patients and controls showed a positive correlation between AT-III and selenium levels (r = 0.27, p = 0.015). After calculatory adjustment for this correlation, selenium was found to be significantly negatively correlated with disease. Multivariate analysis of differences between patients and controls indicated that triglyceride levels in serum had the greatest discriminatory ability (r2 = 0.169), followed by AT-III (r2 = 0.072) and selenium (r2 = 0.056). The increased AT-III levels were correlated with the use of warfarin and beta blockers in the patients, but these drugs could not explain the comparatively low selenium levels in the patients. Serum total cholesterol and plasma fatty acid composition had no discriminatory power in multivariate testing. The various fatty acid did not show co-variation with the selenium levels. The clinical significance of these observations is not clear, but they are consistent with the hypothesis that selenium is an important determinant in cardiovascular disease. The relation between AT-III and selenium should be further evaluated.

Antithrombin III↗
PubMed1976

Selenium in fly ash.

Selenium, at concentrations exceeding 200 parts per million (ppm) (dry weight), has been found in white sweet clover voluntarily growing on beds of fly ash in central New York State. Guinea pigs fed such clover concentrated selenium in their tissues. The contents of the honey stomachs of bees foraging on this seleniferous clover contained negligible selenium. Mature vegetables cultured on 10 percent (by weight) fly ash-amended soil absorbed up to 1 ppm of selenium. Fly ashes from 21 states contained total selenium contents ranging from 1.2 to 16.5 ppm. Cabbage grown on soil containing 10 percent (by weight) of these fly ashes absorbed selenium (up to 3.7 ppm) in direct proportion (correlation coefficient r = .89) to the selenium concentration in the respective fly ash. Water, aquatic weeds, algae, dragonfly nymphs, polliwogs, and tissues of bullheads and muskrats from a fly ash-contaminated pond contained concentrations of selenium markedly elevated over those of controls.

Animals↗
PubMed1994

Accumulation of selenium in a model freshwater microbial food web.

The transfer of selenium between bacteria and the ciliated protozoan, Paramecium putrinum, was examined in laboratory cultures. The population growth of the ciliate was not inhibited in the presence of the highest concentrations of dissolved selenite or selenate tested (10(3) micrograms liter-1). Experiments with radioactive 75selenite or 75selenate indicated that accumulation of selenium by ciliates through time was low when feeding and metabolism were reduced by incubating at 0 degrees C. However, selenium accumulated in ciliate biomass during incubation with dissolved 75Se and bacteria at 24 degrees C and also when bacteria prelabeled with 75Se were offered as food in the absence of dissolved selenium. When 75Se-labeled bacterial food was diluted by the addition of nonradioactive bacteria, the amount of selenite and selenate in ciliates decreased over time, indicating depuration by the ciliates. In longer-term (> 5-day) fed-batch incubations with 75selenite-labeled bacteria, the selenium concentration in ciliates equilibrated at approximately 1.4 micrograms of Se g (dry weight)-1. The selenium content of ciliates was similar to that of their bacterial food on a dry-weight basis. These data indicate that selenium uptake by this ciliate occurred primarily during feeding and that biomagnification of selenium did not occur in this simple food chain.

Animals↗
PubMed1998

Enteral yeast-selenium supplementation in preterm infants.

AIM: To study the bioavailability of selenium enriched yeast in preterm infants living in a low selenium area (Hungary). METHODS: Thirty six preterm infants were randomly assigned to two groups at birth with respect to selenium supplementation. In the supplemented group (n = 18) infants received 4.8 mg of selenium enriched yeast containing 5 micrograms selenium daily. RESULTS: In the supplemented group the serum selenium concentration increased from 36.1 (+/- 12.8) micrograms/l to 43.5 (7.9) micrograms/l and in the non-supplemented group it decreased from 34.4 (20.4) micrograms/l to 26.1 (16.6) micrograms/l from birth in two weeks. No complications or side effects as a result of supplementation were observed. CONCLUSIONS: Selenium enriched yeast is a safe and an effective form of short term enteral selenium supplementation for preterm infants.

Biological Availability↗
PubMed1985

Concentration of selenium in plasma and erythrocytes during total parenteral nutrition in Crohn's disease.

Plasma- and erythrocyte-selenium concentrations were determined in five consecutive patients with Crohn's disease given preoperative total parenteral nutrition - nil per os - for a mean period of 34 days per patient. No blood components were administered during the total parenteral nutrition. Before the total parenteral nutrition the plasma-selenium level and, to a less extent, the erythrocyte-selenium levels were below the reference values. After three weeks of total parenteral nutrition both concentrations had fallen. There were, however, clinical and biochemical signs of improvement during the total parenteral nutrition, as indicated by an increase in body weight, P-albumin and P-transferrin. In one female patient given 39 days of preoperative total parenteral nutrition containing 0.06 mumol (5 micrograms) selenium per 24 h the decreasing levels of plasma-selenium and erythrocyte-selenium were both correlated to the duration of the total parenteral nutrition (r = 0.87 and 0.96, respectively). The results suggest that total parenteral nutrition patients may be at risk for selenium deficiency, and that a supplementary administration of selenium via total parenteral nutrition may be required.

Adult↗
PubMed1995

Sulfation pathway of thyroid hormone metabolism in selenium-deficient male rats.

Male Sprague-Dawley rats were fed a selenium-deficient yeast-based laboratory diet or a control diet for 6 wk. The tissue type I 5'-monodeiodinase (5'-MDI) activity and the immunoassayable 5'-MDI were significantly (P < 0.05) reduced in the liver and the kidney but not in the thyroid of selenium-deficient rats. The mean serum concentrations of thyroxine sulfate (T4S), 3,3',5'-triiodothyronine sulfate (T3S), and reverse T3 sulfate (rT3S) (ng/dl) were significantly increased in selenium-deficient rats (15.7, 59.4, and 22.8, respectively, n = 12) compared with control rats (< 1.0, 18.5, and 9.1, respectively, n = 12, P < 0.01). Kinetic studies were carried out during a constant infusion of unlabeled sulfated iodothyronines (T4S, T3S, or rT3S, n = 5-6/group) at a rate of 1 microgram/h by Alzet minipump for 48 h. The data showed that elevated serum concentrations of T4S or T3S in the selenium-deficient rat are due both to reduced metabolic clearance rate (MCR, mean, l.kg-1.day-1, 7.4 for T4S and 4.5 for T3S in selenium deficiency vs. 12 and 9.2, respectively in controls, P < 0.05) and increased production rate (mean, microgram.kg-1.day-1, 1.2 for T4S, and 2.7 for T3S in selenium deficiency vs. 0.12 and 1.7, respectively, in the controls, P < 0.05). However, the increased serum rT3S concentration in selenium-deficient rats is due mainly to reduced MCR (mean, l.kg-1.day-1, 34 vs. 67 in controls, P < 0.05) and its daily production rate remained unchanged in selenium deficiency (mean, microgram.kg-1.day-1, 7.6 vs. 6.1 in the control group, P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2004

Selenium deficiency abrogates inflammation-dependent plasma cell tumors in mice.

The role of the micronutrient, selenium, in human cancers associated with chronic inflammations and persistent infections is poorly understood. Peritoneal plasmacytomas (PCTs) in strain BALB/c (C), the premier experimental model of inflammation-dependent plasma cell transformation in mice, may afford an opportunity to gain additional insights into the significance of selenium in neoplastic development. Here, we report that selenium-depleted C mice (n = 32) maintained on a torula-based low-selenium diet (5-8 micro g of selenium/kg) were totally refractory to pristane induction of PCT. In contrast, 11 of 26 (42.3%) control mice maintained on a selenium adequate torula diet (300 micro g of selenium/kg) and 15 of 40 (37.5%) control mice fed standard Purina chow (440 micro g of selenium/kg) developed PCT by 275 days postpristane. Abrogation of PCT was caused in part by the striking inhibition of the formation of the inflammatory tissue in which PCT develop (pristane granuloma). This was associated with the reduced responsiveness of selenium-deficient inflammatory cells (monocytes and neutrophils) to chemoattractants, such as thioredoxin and chemokines. Selenium-deficient C mice exhibited little evidence of disturbed redox homeostasis and increased mutant frequency of a transgenic lacZ reporter gene in vivo. These findings implicate selenium, via the selenoproteins, in the promotion of inflammation-induced PCT and suggest that small drug inhibitors of selenoproteins might be useful for preventing human cancers linked with chronic inflammations and persistent infections.

Animals↗
PubMed2006

Delineating the mechanism by which selenium deactivates Akt in prostate cancer cells.

The up-regulation of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway is prevalent in many cancers. This phenomenon makes PI3K and Akt fruitful targets for cancer therapy and/or prevention because they are mediators of cell survival signaling. Although the suppression of phospho-Akt by selenium has been reported previously, little information is available on whether selenium modulates primarily the PI3K-phosphoinositide-dependent kinase 1 (PDK1) side of Akt phosphorylation or the phosphatase side of Akt dephosphorylation. The present study was aimed at addressing these questions in PC-3 prostate cancer cells which are phosphatase and tensin homologue-null. Our results showed that selenium decreased Akt phosphorylation at Thr308 (by PDK1) and Ser473 (by an unidentified kinase); the Thr308 site was more sensitive to selenium inhibition than the Ser473 site. The protein levels of PI3K and phospho-PDK1 were not affected by selenium. However, the activity of PI3K was reduced by 30% in selenium-treated cells, thus discouraging the recruitment of PDK1 and Akt to the membrane due to low phosphatidylinositol-3,4,5-trisphosphate formation by PI3K. Consistent with the above interpretation, the membrane localization of PDK1 and Akt was significantly diminished as shown by Western blotting. In the presence of a calcium chelator or a specific inhibitor of calcineurin (a calcium-dependent phosphatase), the suppressive effect of selenium on phospho-Akt(Ser473) was greatly reduced. The finding suggests that selenium-mediated dephosphorylation of Akt via calcineurin is likely to be an additional mechanism in regulating the status of phospho-Akt.

3-Phosphoinositide-Dependent Protein Kinases↗
PubMed2005

Selenium, selenoproteins and vision.

Selenium biochemistry is reviewed in respect to its presumed relevance to age-related ocular diseases. Selenium is an essential trace element that exerts its physiological role as selenocysteine residue in at least 25 distinct selenoenzymes in mammals. Lack of GPx-1 due to alimentary selenium deprivation has been inferred to induce cataract in rats and was demonstrated to cause cataracts in mice by targeted gene disruption. The role of other selenoproteins in the eye remains to be worked out. Selenium in excess of the tiny amounts required for selenoprotein synthesis is toxic in general and causes cataracts in experimental animals. Clinical evidence for a protective role of selenium in the development of cataract, macula degeneration, retinitis pigmentosa or any other ocular disease is not available, likely because suboptimum selenium intake, as it may result from unbalanced diet, does not cause any pathologically relevant selenium deficiency in the eye. At present, there is neither theoretical nor an empirical basis to expect beneficial effects of selenium supplementation beyond the dietary reference intakes of 55 microg/day in the context of ocular diseases.

Diet↗
PubMed2006

Food intake and serum selenium concentration in elderly people.

BACKGROUND/AIMS: It is becoming apparent that the essential trace element selenium plays a critical role in the maintenance of optimal health status. The objective of this study was to identify the food groups that most contributed to selenium intake and its serum levels in elderly people. METHODS: Dietary intake was assessed in 205 institutionalized elderly by means of a 1-year food frequency questionnaire (FFQ). Intake of macronutrients and minerals of the diet were estimated. Selenium was determined in serum and analyzed by graphite-furnace atomic absorption spectrometry. RESULTS: Selenium intake and serum concentration were both within the normal range. The major contributors to selenium intake were cereals and bakery, fish and shellfish, meat and meat products and dairy products. All of them except cereals were also associated to serum selenium. Intake of animal protein, but not the vegetable one, contributed to serum selenium. CONCLUSION: An adequate intake of fish and meat would be of importance to improve selenium status and health principally in elderly people who are at high risk of mineral deficiency.

Aged↗
PubMed2002

Fulminant heart failure due to selenium deficiency cardiomyopathy (Keshan disease).

Selenium deficiency is a rare cause of cardiomyopathy that may be encountered by the forensic pathologist. Selenium deficiency is associated with a cardiomyopathy, myopathy and osteoarthropathy. In Asia and Africa, dietary selenium deficiency is associated with a cardiomyopathy known as Keshan disease and an osteoarthropathy called Kashin-Beck disease. Chronic selenium deficiency may also occur in individuals with malabsorption and long term selenium-deficient parenteral nutrition. Selenium deficiency causes myopathy as a result of the depletion of selenium-associated enzymes which protect cell membranes from damage by free radicals. We present a case of fulminant heart failure in a middle aged woman with a complex medical and surgical history including documented malabsorption and selenium deficiency. Pathological examination of the heart showed features consistent with Keshan disease.

Adult↗
PubMedDate not supplied

Selenium concentrations in pancreatic juice of patients with chronic pancreatitis.

BACKGROUND: Free radicals have been implicated as an important mediator in the pathogenesis of tissue injury. Experimental animal models would suggest selenium deficiency contributes to the pathogenesis of chronic pancreatitis (CP). In clinical studies, low plasma selenium levels have been reported in patients with CP. To the best of our knowledge, selenium levels have not been measured in pancreatic juice. METHODS: Twenty-seven patients with chronic intermittent upper quadrant abdominal pain were studied. The diagnosis of CP was made by endoscopic retrograde cholangiopancreatography. Patients were allowed to eat an ad libitum western diet. None of the patients was taking selenium supplements. Patients underwent upper endoscopy with routine conscious sedation. Secretin (0.2 microg/kg) was given i.v. immediately before intubation. Pancreatic juice collected from the duodenum was immediately frozen in liquid nitrogen and stored at -80 degrees C until the assay was performed. Selenium levels of the pancreatic juice were determined using the inductively coupled plasma-mass spectrometry method. RESULTS: Twelve patients had an abnormal pancreatogram. The gender and median age in controls and CP were 11 females and 4 males (54 years, range 32-78) and 7 females and 5 males (56 years, range 37-79), respectively. The etiology of CP was alcohol and idiopathic. The median selenium concentration in controls was 4 microg/mL (range, 2-11.5) and in CP 4.5 microg/mL (range, 2-16). There was not a statistically significant difference between the 2 groups (p = not significant). CONCLUSIONS: The pancreatic juice concentration of selenium is similar in patients with CP compared with age matched controls. Our results would therefore suggest that the effects of selenium on pancreatic injury might be systemic rather than local tissue effect.

Abdominal Pain↗
PubMedDate not supplied

Suboptimal selenium status in home parenteral nutrition patients with small bowel resections.

The selenium status of 13 adult home parenteral nutrition (HPN) patients was evaluated using 12 healthy adult volunteers as controls. Patients had been maintained on HPN for a mean of 36 months and averaged 121 cm of residual small bowel. Prospective diet surveys in patients indicated a mean oral caloric intake of 902 kcal/day. The mean plasma selenium concentrations (microgram/g) were 0.044 in patients and 0.117 in controls (p less than 0.01). The erythrocyte glutathione peroxidase activities, as mumol of NADPH oxidized/g hemoglobin/min, averaged 11.01 in patients and 31.76 in controls (p less than 0.01). Four patients exhibited myalgic symptomatology suggestive of clinical selenium deficiency. No correlations could be ascertained between plasma selenium levels and glutathione peroxidase activities in either patients or controls. Additionally, in the patient group, no significant correlations could be ascertained between selenium status and oral caloric intake, residual small bowel length, symptomatology suggestive of deficiency or HPN duration. However, since sample size was not large, lack of correlations might best be considered suggestive not conclusive. The data indicate that HPN patients with small bowel resections exhibit suboptimal selenium status and may be at risk of developing clinically evident selenium deficiency. HPN patients should be prophylactically supplemented with selenium regardless of oral intake, duration of HPN, or residual length of resected small bowel.

Adult↗
PubMed2006

Low serum albumin and the acute phase response predict low serum selenium in HIV-1 infected women.

BACKGROUND: Low serum selenium has been associated with lower CD4 counts and greater mortality among HIV-1-seropositive individuals, but most studies have not controlled for serum albumin and the presence of an acute phase response. METHODS: A cross-sectional study was conducted to evaluate relationships between serum selenium concentrations and CD4 count, plasma viral load, serum albumin, and acute phase response markers among 400 HIV-1-seropositive women. RESULTS: In univariate analyses, lower CD4 count, higher plasma viral load, lower albumin, and the presence of an acute phase response were each significantly associated with lower serum selenium concentrations. In multivariate analyses including all four of these covariates, only albumin remained significantly associated with serum selenium. For each 0.1 g/dl increase in serum albumin, serum selenium increased by 0.8 microg/l (p < 0.001). Women with an acute phase response also had lower serum selenium (by 5.6 microg/l, p = 0.06). CONCLUSION: Serum selenium was independently associated with serum albumin, but not with CD4 count or plasma viral load, in HIV-1-seropositive women. Our findings suggest that associations between lower serum selenium, lower CD4 count, and higher plasma viral load may be related to the frequent occurrence of low serum albumin and the acute phase response among individuals with more advanced HIV-1 infection.

Acute-Phase Reaction↗
PubMed2003

Determination of selenium in human serum by liquid chromatography/electron capture atmospheric pressure chemical ionization mass spectrometry after acid digestion and derivatization using 2,3-diaminonaphthalene.

Analysis of selenium in biological samples is very important and numerous analytical methods for the element have been developed. One of the most convenient and widely used methods for routine determination of serum selenium is a fluorometric method using 2,3-diaminonaphthalene (DAN); however, this method lacks specificity. We observed that 4,5-benzopiazselenol (BPS), a selenium derivative of DAN, is ionized with electron capture in an atmospheric pressure chemical ionization (APCI) interface, and subsequently established a method for determining total human serum selenium by means of liquid chromatography/atmospheric pressure chemical ionization mass spectrometry. All pretreatment procedures were carried out in a single test tube to minimize selenium loss. The recovery of organic or inorganic selenium spiked to human serum was 97-103%. The detection limit of BPS was equivalent to 0.2 ng of selenium and the lower quantitative limit of serum selenium was 10 ng mL(-1). The coefficient of variation of standard concentrations in control serum samples was 4.5%. The purity of the observed peak obtained from serum samples was confirmed using the ion cluster technique.

2-Naphthylamine↗
PubMed2005

Selenium and mortality in the elderly: results from the EVA study.

BACKGROUND: Inadequate plasma selenium can adversely affect the maintenance of optimal health; therefore, reported decreases in plasma selenium in an aging population are cause for concern. To further examine this hypothesis, we explored the relationships between plasma selenium and mortality in an elderly population: the EVA (Etude du Vieillissement Artériel) study. METHODS: The EVA study was a 9-year longitudinal study with 6 periods of follow-up. During the 2-year period from 1991 to 1993 (EVA0), 1389 men and women born between 1922 and 1932 were recruited. The effects of plasma selenium at baseline on mortality were determined by Cox proportional hazards regression analysis, adjusting for the following variables: sociodemographic characteristics, dietary habits, health, and cognitive factors. RESULTS: During the 9-year follow-up, 101 study participants died. Baseline plasma selenium was higher in individuals who were alive at the end of follow-up [mean (SD), 1.10 (0.20) micromol/L] than in those who died during the follow-up [1.01 (0.20) micromol/L; P <10(-4)]. Mortality rates were significantly higher in individuals with low selenium [increments = 0.2 micromol/L; relative risk (RR) = 1.56 (95% confidence interval, 1.28-1.89)]. After we controlled for various potential confounding factors, this association remained significant [RR = 1.54 (1.25-1.88)]. When the underlying causes of death were considered, we found an association with cancer-related mortality [adjusted RR = 1.79 (1.32-2.44)]. CONCLUSIONS: Even if it is premature to present selenium as a longevity indicator in an elderly population, our results are in accordance those of large, interventional, randomized trials with selenium, which suggest that this essential trace element plays a role in health maintenance in aging individuals.

Aged↗