Serum Se Concentrations Research Articles

Comparing functional metabolic effects of marginal and sufficient selenium supply in sheep

This study was performed to characterise key data of long-term ovine Se metabolism and to work out the best biomarker of Se status. An upgrade from marginal (<0.05mg Se/kg diet, ‘Se−’) to sufficient (0.2mg Se/kg diet, ‘Se+’) nutritional Se supply using sodium selenite was monitered biweekly by analysing Se concentration, glutathione peroxidase (Gpx) activity and routine biochemistry in blood/serum over 2 years. Se, Cu, Zn, cytosolic Gpx and thioredoxin reductase (TrxR) activity were measured in the liver (biopsies/post-mortem). Se, Gpx, TrxR, glutathione-S-transferase-alpha (aGST) and iodothyronine deiodinase (Dio1) were analysed in the kidney, heart muscle and thyroid. Relative mRNA expression of hepatic aGST1 and Gpx1 was determined.Improvement of Se supply strongly increased serum and liver Se concentration within 10 and 20 days, respectively followed by a plateau. Whereas the achievement of a maximum whole blood Gpx activity was reached after 3 months, serum Gpx3 activity increased with high variations. Hepatic Gpx activity reached a maximum during days 100–200, decreasing thereafter. Distinct group differences in Se and cytosolic Gpx activity were evident in all organs (except Se in kidney). TrxR and Dio1 activity was affected only in the liver. The Se− sheep showed an ongoing decrease in serum Se concentration within 2 years, whereas liver Se remained almost unaffected. High relative Gpx1 mRNA expression in the Se+ group was consensual to high hepatic Gpx activity. Relative mRNA expression of hepatic aGST1 was higher in the Se− sheep. Clinical signs and abnormalities in routine biochemistry were absent.In summary, the best biomarker of Se deprivation and nutritional Se upgrade, respectively was Se in serum. Moreover, hepatic Se concentrations reliably reflected the upgrade of Se supply within days. Whole blood Gpx reacts slowly depending on newly formed erythrocytes restricting its diagnostic use. Vital organs are affected by Se deficiency due to a decrease of cytosolic Gpx activity attenuating the antioxidative system. Cellular up-regulation of aGST1 mRNA expression in the Se− group is assumed to partially compensate for the decreased antioxidant defence due to a loss in Gpx activity. This sheep model appears advantageous for long-term studies on sub-clinical metabolic effects in experimental modifiable nutritional Se supply.

Diagnosis of the Cu and Se status of dairy cattle in New Zealand: How many samples are needed?

AIM: To determine the minimum number of samples required to obtain a robust estimate of the Cu and Se status of dairy herds, as assessed by determining liver Cu and serum Se concentrations. METHODS: Results were collated from analyses of samples of liver from 18 dairy herds and serum from 19 herds, for concentrations of Cu and Se, respectively. All herds were in either the Manawatu or Rangitikei regions of the North Island of New Zealand. Data were used to determine the required sample size for each herd; firstly to estimate the population mean with 90% confidence with a precision of 27.5 nmol/L for Se in serum, and 100 μmol/kg fresh weight (FW) for Cu in liver; and secondly to ensure that the 90% CI of the sample mean did not include specified thresholds for concentrations of Se or Cu. RESULTS: For Se concentration in serum, the SD of each batch varied from 0.5–147 nmol/L, and for Cu concentration in liver, the SD varied from 173–829 μmol/kg FW. For Se, the minimum sample size required to estimate the population mean to within 27.5 nmol/L with 90% confidence was >10 for 13/19 batches. For Cu, the minimum sample size required to estimate the population mean to within 100 μmol/kg FW was >10 for 17/18 batches. When estimating required sample size based on 90% CI and a threshold value, the minimum sample size to confirm the population mean of Se was >140 nmol/L was four in 17/18 batches where the sample mean was>140 nmol/L. For concentrations of Cu in liver, ≤8 samples would have been sufficient for a threshold of 45 μmol/kg FW in 16/18 batches. For the 95 μmol/kg threshold, the minimum required was 12. For the threshold of 300 μmol/kg FW, 6/17 batches with a mean >300 μmol/kg FW required≤20 samples. CONCLUSIONS: From this dataset of 21 herds, the sample size recommendation for ensuring that the population mean of Se concentration was not below the marginal threshold was similar to previous recommendations. For Cu concentrations in liver, the estimated sample size recommendations for ensuring that the population mean was not below the marginal threshold was much larger than currently recommended. CLINICAL RELEVANCE: In dairy cattle, five to six blood samples per group should be taken to determine Se status, and to effectively monitor Cu status a minimum of 12 liver samples should be taken, preferably in the autumn.

Evaluation of Copper Concentration in Subclinical Cases of White Muscle Disease and Its Relationship with Cardiac Troponin I

The present study aims to evaluate the serum level of copper (Cu) in lambs suffering from subclinical forms of white muscle disease (WMD) and its relationship with cardiac troponin I (cTn-I) as a novel biomarker of cardiovascular disorders. Ten milliliters of jugular blood were taken from 200 lambs less than one year old to measure serum concentrations of Cu, selenium (Se), and cTn-I. The subjects were divided into 2 groups, namely, the deficient group which included 36 lambs, and the control group which included 164 lambs according to the reference serum Se concentration (50 ng/mL). Serum Se levels in the deficient group were lower than 50 ng/mL. By contrast, the control group showed Se levels higher than 50 ng/mL. Differences among the serum Cu and cTn-I levels were determined in both groups. The mean ±SD and median of serum Cu and cTn-I levels in the deficient group were lower and higher than those in the control group, respectively. A significant positive correlation was observed between serum Cu and Se levels, and also serum Cu and Se levels showed a negative correlation with serum cTn-I concentrations. Stepwise linear regression analysis showed that serum Cu levels were correlated positively with serum Se levels (p<0.05). Receiver operating characteristic (ROC) curve analysis indicated that the area under curve (AUC) of Cu was significantly higher than that of cTn-I based on the reference diagonal line. It is important to keep in mind that the value of AUC for the ROC curve is between 0.5 and 1.00, in which the lowest accuracy is related to the reference diagonal line with AUC of 0.5. A cut-off was determined to indicate which Cu level can discriminate between affected and healthy lambs. The cut-off level, sensitivity, and specificity of Cu in this study were 144.5 ng/mL, 74%, and 61%, respectively.

The Dietary Acrylamide Intake Adversely Affects the Serum Trace Element Status

Acrylamide is an organic chemical which occurs in foods widespreadly consumed in diets worldwide. The purpose of this study was to evaluate the serum trace element levels (Fe, Cu, Zn, Mn, Cr, Se, Co, Ni, V, As, Mg, P, Li, K, Al) in Wistar rats exposed to acrylamide. Acrylamide was administered to the treatment groups at 2 and 5 mg/kg body weight (bw)/day via drinking water for 90 days. Inductively coupled plasma mass spectrometry was used for the determination of serum trace element concentrations. Serum Zn, Se, Co, V and Mg concentrations of 5 mg/kg bw/day acrylamide-treated male rats were lower, whereas serum As concentration was higher than the same parameters of the controls rats. Similarly, serum Zn, Se, Co, V and Mg concentrations were decreased in 5 mg/kg bw/day acrylamide-treated female rats compared with control rats. On the other hand, there were no significant differences between serum Fe, Cu, Mn, Cr, Ni, P, Li, K and Al concentrations of all groups. The results from this study provide evidence that dietary acrylamide intake adversely affects the serum trace elements status.

Effect of selenium and vitamin E supplementation during late pregnancy on colostrum and plasma Se, Cu, Zn and Fe concentrations of fat tail Sanjabi ewes and their lambs

Twenty seven fat tail ewes were randomly assigned to three treatment groups. Four and two weeks before expected lambing, ewes were injected intramuscularly 0 ml (C) 5 ml (T1), 10 ml (T2) selenium and vitamin E respectively. Blood samples were collected from ewes four weeks before expected lambing and on the day of lambing. Blood samples of their lambs were taken from the jugular vein at birth and 7 days of age. Selenium, copper, zinc and iron concentrations of plasma and colostrum were measured by inductively couple plasma (ICP-OES). The plasma Se concentration of lambs in T2 was significantly increased compared with control group at 7 days of age (P &lt; 0.05). The colostrums Se and Cu concentrations were significantly increased in Se supplemented ewe and their lambs (P &lt; 0.05). The plasma Zn concentration of ewes at lambing and colostrum were significantly decreased in T2 compared with controls. The plasma Zn concentration of lambs of ewes of T2 was significantly decreased compared with other groups at 7 days of age (P &lt; 0.05). The serum concentration of Cu increased in supplemented ewes, which was concomitant with a reduction in Zn concentration in serum and colostrums. It seems that an increase in serum concentration of Cu at the end of pregnancy in ewes given Se supplement could disturb the Zn: Cu ratios which in turn lead to Zn reduction. There was a positive correlation between serum Se concentration with Cu and Fe levels and also a negative correlation between Se and Zn in treated ewes.

Serum trace elements and risk of malnutrition in institutionalised elderly

The objective of this work is to evaluate the association between Selenium (Se)-, Copper (Cu)- and Zinc (Zn)-circulating concentrations and indicators of nutritional status. This study enroled 428 institutionalised elderly. The diagnostic tools used are a form to collect data regarding gender, age, duration of stay in nursing home, number of prescribed drugs, chronic diseases, Mini Nutritional Assessment (MNA), anthropometric measurements, albumin, transferrin and serum concentrations of Se, Cu and Zn. The collected data were analysed with descriptive assessments of the differences χ(2), Student's t-test and analysis of variance. Multivariate linear regression were performed to evaluate the association between the concentrations of each trace elements and the other variables. The study population was represented by 327 women and 101 men, of whom 13.8% were 65-75 years old and 47.4% were older than 85 years. According to the MNA score, 58.4% were at risk of malnutrition and 21.3% were malnourished. The results show a significant reduction in the average concentrations of Se and Zn in women when the nutritional status gets worse. The same trend, although not statistically significant, is also observed in men. In both genders, the Cu concentration does not show a statistically significant association with nutritional status. Multivariate linear regression show some positive or negative associations. Our study seems to confirm the association between Se and nutritional status, as well as with some blood chemistry parameters. The length of institutionalisation seems to be an independent predictor of Se concentration.

CLINICAL ACTIVITY SCORES ARE IMPROVING IN PATIENTS WITH MILD THYROID-ASSOCIATED ORBITOPATHY RECEIVING ADJUVANT SELENIUM SUPPLEMENTATION

The essential trace element selenium (Se) exerts complex effects on the endocrine and immune systems, partly due to its antioxidant capacity. The importance of an optimal Se intake has been established in autoimmune thyreoiditis. A recently published study reported beneficial results in Se supplemented patients with mild Graves’ orbitopathy. Eight female patients with mild Graves’ orbitopathy and three female patients with mild orbitopathy based on Hashimoto thyreoiditis participated in the study. The status of the orbita was registered at the beginning of the study and one-six months thereafter both according to the scores recommended by the American Thyroid Association (ATA) and clinical activity scores (CAS). The patients were treated according to their thyroid hormone status, their antibody results and their CAS. Moreover, they received adjuvant Se as 100 or 200 μg sodium-selenite. Serum Se concentrations were measured before Se supplementation was implemented and 1-6 months after the beginning of treatment. ATA scores improved in 10 patients and worsened slightly in one female patient. CAS improved in all study participants. Mean Se concentrations were 75.08±11.55μg/l before supplementation was started and 91.35±17.37μg/l one-eight months later (p<0.05). At the beginning of the study, the majority of patients exhibited elevated antibody levels. After conventional treatment and adjuvant Se supplementation, antibody levels decreased or reached the normal range (except in the case of one patient).

Selenoprotein P Status Correlates to Cancer-Specific Mortality in Renal Cancer Patients

Selenium (Se) is an essential trace element for selenoprotein biosynthesis. Selenoproteins have been implicated in cancer risk and tumor development. Selenoprotein P (SePP) serves as the major Se transport protein in blood and as reliable biomarker of Se status in marginally supplied individuals. Among the different malignancies, renal cancer is characterized by a high mortality rate. In this study, we aimed to analyze the Se status in renal cell cancer (RCC) patients and whether it correlates to cancer-specific mortality. To this end, serum samples of RCC patients (n = 41) and controls (n = 21) were retrospectively analyzed. Serum Se and SePP concentrations were measured by X-ray fluorescence and an immunoassay, respectively. Clinical and survival data were compared to serum Se and SePP concentrations as markers of Se status by receiver operating characteristic (ROC) curve and Kaplan-Meier and Cox regression analyses. In our patients, higher tumor grade and tumor stage at diagnosis correlated to lower SePP and Se concentrations. Kaplan-Meier analyses indicated that low Se status at diagnosis (SePP<2.4 mg/l, bottom tertile of patient group) was associated with a poor 5-year survival rate of 20% only. We conclude that SePP and Se concentrations are of prognostic value in RCC and may serve as additional diagnostic biomarkers identifying a Se deficit in kidney cancer patients potentially affecting therapy regimen. As poor Se status was indicative of high mortality odds, we speculate that an adjuvant Se supplementation of Se-deficient RCC patients might be beneficial in order to stabilize their selenoprotein expression hopefully prolonging their survival. However, this assumption needs to be rigorously tested in prospective clinical trials.

The effect of dietary organic and inorganic selenium supplementation on serum Se, Cu, Fe and Zn status during the late pregnancy in Merghoz goats and their kids

The present study aims to determine the effect of dietary Se supplement on Merghoz goats at the last stage of gestation on serum Se, Cu, Zn and Fe status of goats and their kids. Thirty Merghoz does (30±3kg) were fed the same basal diet containing 0.11mgSekg−1 DM and randomly assigned to one of three dietary treatments in a randomized complete block design. Three weeks before the expected kidding, the basal diet was supplemented with 0 (control) or 0.3mgSehead−1d−1 in the form of l-selenomethionin (Se-Met) and 0.3mgSehead−1d−1 in the form of sodium selenite (SS). Blood samples were collected from the does three weeks before the expected kidding and on the kidding day. Blood samples of newborn kids were also taken from the jugular vein at birth and 7 days of age. The results indicated that the serum concentration of Se increased in supplemented does compared with the control ones. The selenium concentration was also significantly increased in colostrum of treated does (P<0.05). There was no significant difference between Se sources on the Se status although there was higher efficiency of Se-Met than sodium selenite supplement. The serum concentration of copper increased in supplemented doses, which was concomitant with a reduction in Zn concentration in serum and colostrums. It seems that an increase in serum concentration of Cu at the end of pregnancy in goats given Se supplement could disturb the Zn:Cu ratios which in turn lead to Zn reduction. Serum Se, Cu and Fe concentrations of kids of treated doses increased at birth and first week of age, while the serum concentration of Zn decreased in newborn kids. It seemed that there was a positive correlation between serum Se concentration with Cu and Fe levels and also a negative correlation between Se and Zn in treated dose (P<0.05).

Comparative effects of nano elemental selenium and sodium selenite on selenium retention in broiler chickens

Two experiments were performed to explore the selenium retention of Nano elemental selenium (Nano-Se) in Arbor Acre male broiler chickens as compared with sodium selenite. A 2×4 factorial arrangement with 0.15, 0.30, 0.60 and 1.20mg/kg dietary Se from Nano-Se or sodium selenite added to a maize–soybean meal diet was conducted to study the effects of Se source and level on growth performance, serum glutathione peroxidase (GSH-Px) activity, Se concentration in serum and tissue. Furthermore, selenium retention of Nano-Se and selenite was determined in chicks by the oral or intravenous administration of the radiolabeled Se and the in vivo ligated intestinal loop procedure. As for selenite, average daily gain (ADG), gain/feed and survival ratio reached a plateau at the Se concentration of 0.15–0.30mg/kg and then declined as supplemental selenite increased. As for Nano-Se, ADG, gain/feed and survival ratio reached a plateau at the Se concentration of 0.15–1.20mg/kg. Survival ratio, ADG and gain/feed increased quadratically (P<0.05) as dietary selenite increased (P<0.05), and increased linearly and quadratically (P<0.05) as dietary Nano-Se increased (P<0.05). Selenium concentrations in serum, liver and breast muscle increased linearly and quadratically (P<0.05) as the dietary Se level increased for either Se source, but the magnitude of increase was substantially greater (P<0.05) when Nano-Se was fed. Retention of the orally or intravenously administered 75Se showed that the percentages of Nano-Se in the whole body and liver tissue were much higher (P<0.05) than those of selenite. Intestinal transport of 75Se from ligated loop to body showed that the transfer of Nano-Se from the intestinal lumen to the body was higher (P<0.05) than that of selenite, while the intestinal retention of Nano-Se was lower (P<0.05) than that of selenite. The results showed that the range between optimal and toxic dietary levels of Nano-Se was wider than that of sodium selenite, and Nano-Se was more efficiently retained in the body than sodium selenite.

Oocyte aspiration and in vitro embryo production in Jersey cows with selenium-supplemented diet

The effects of selenium (Se) in Jersey cows' diet on the aspiration of oocytes and production of embryos in vitro were studied. Groups with five Jersey cows received 3.2mg or 9.6mg Se daily, provided in the feed concentrate. Six follicular aspirations were carried out every 15 days, using only the last 5. The oocytes were classified, and standard procedures were carried out for maturation, fertilization and cultivation. The total number of oocytes (35.11±2.65 vs 23.10±2.16) and degree 1 oocytes (11.61±2.65 vs 4.75±0.97) were higher in the group that received 9.6mg Se and the quantity of naked oocytes (3.23±0.87 vs 6.22±1.18) was lower in this group. The aspirated oocytes from the cows treated with 9.6mg Se/day resulted in higher (P&lt;0.05) embryo production 21.98±2.37 vs 13.12±1.59). No difference was observed in serum Se concentration between the two groups. It is recommended that the daily diet be supplemented with 100g mineral salt containing 9.6mg Se, since this rate rendered a larger production of oocytes, higher quantity of degree 1 oocytes and greater production of embryos in the process of in vitro fertilization.

Serum selenium and selenoprotein P in patients with silicosis

ObjectivesSelenoprotein P (SeP) is a selenium (Se) supply protein, which is an antioxidant micronutrient considered to be vital for human health. The aim of this study was to assess the serum selenium status in patients with silicosis. MethodsWe conducted a retrospective case–control study where serum samples from a total of 78 patients (males with a median age of 73.5 years old) with silicosis and 20 healthy controls (males with a median age of 72.5 years old) were assayed for Se and SeP. They underwent medical and job history taking, lung function testing, and chest radiography examinations. Levels of serum Se were measured using electrothermal atomic absorption spectrophotomerty, while levels of SeP were assessed with sandwich Enzyme Immunoassay. Spearman's rank correlation test was carried out to evaluate the relationship between Se and SeP. The Mann–Whitney test was used to evaluate differences in serum Se and SeP between study groups. ResultsThe median serum Se and SeP concentrations were significantly lower in cases (74.0μg/l and 4.2mg/l, respectively) compared with controls (116.0μg/l and 5.8mg/l, respectively). In both cases and controls, serum Se was positively correlated with serum SeP (rho=0.781, p<0.001 and rho=0.768, p<0.001, respectively). Serum Se and SeP levels were significantly lower in patients classified in category four compared with those who were classified in category two or three. ConclusionsSerum Se and SeP concentrations were found to be at inadequate levels in patients with silicosis, and decreased significantly with the severity of the disease.

Selenium and cancer prevention: Observations and complexity

Early case–control and intervention studies suggested that selenium (Se) species might reduce the risk of cancer and in a pre-diagnostic case–control study from 1986 [1] we found that the higher the serum Se concentration, the lower was the odds ratio of thyroid cancer. Our data showed, however, that this observation occurred late in the pre-diagnostic period indicating that low serum Se was simply a consequence of thyroid cancer. In 1986 we therefore concluded that the only way to get an indisputable and lasting answer to the question was to carry out properly designed intervention studies. Great was our frustration therefore when we in 2003 [2] discovered that thyroid cancer morbidity is a fractal variable powered by such complexity that we may never find a definite and enduring answer: Even the best, randomised, controlled trial comparing the incidence rate among exposed and controls can only produce temporary answers due to the complexity background. The only possible way to come up with a lasting solution seems to be by means of reductionist experiments, but they have to be tested on man and then one is back to square one.

Daily intake of selenium and concentrations in blood of residents of Riyadh City, Saudi Arabia

Concentrations of selenium (Se) in food from local markets of Riyadh, Kingdom of Saudi Arabia (KSA) were measured and daily intake calculated based on information from a questionnaire of foods eaten by healthy Saudis. The daily intake of Se was then compared to concentrations of Se in blood serum. Primary sources of Se in the diet of Saudis were as follows: meat and meat products (31%), egg (20.4%), cereals and cereal products (16%), legumes (8.7%), fruits (6.8%), milk and dairy products (2.0%), beverages (2%), sweets (1.8%), pickles (0.2%), and oil (0.02%). Daily intake of Se, estimated to be 93 μg Se/person/day, was slightly greater than that calculated from the Food and Agriculture Organization (FAO) food balance sheet for KSA, which was approximately 90 μg Se/person/day. The daily intake of Se by Saudis in Riyadh was greater than that of Australians or Dutch but less that of Canadians and Americans. There was a statistically significant correlation (R = +0.38, P < 0.05) between daily intake of Se and concentrations of Se in blood serum of Saudis in Riyadh. The mean concentration of Se in serum was 1.0 × 10(2) ± 30.5 μg Se/l. Taken together, the results suggest that the average Se intake and Se serum concentrations are within the known limits and recommendations, making it unlikely that Saudis are on average at risk of deficiency or toxicity.

Effects of selenium supplementation in the early stage of autoimmune thyroiditis in childhood: an open-label pilot study

The aim of the study was to evaluate the role of selenium (Se) in childhood autoimmune thyroiditis regarding its effect on thyroid-stimulating hormone (TSH), free thyroxine (fT4), thyroid peroxidase antibodies (TPOAb), thyroglobulin antibody (TgAb), and thyroid morphology. Newly diagnosed 23 euthyroid children (mean age, 12.3 +/- 2.4 years) with Hashimoto thyroiditis (HT) received only 50 microg L-selenomethionine per day for 3 months. The baseline basal urinary iodine level, serum Se, TSH, fT4, TPOAb, and TgAb concentrations, and thyroid morphology by ultrasound were detected. We reanalyzed the TPOAb and TgAb changes at the 3rd month and then compared the thyroid morphology with 30 healthy individuals (mean age, 12.1 +/- 2.1 years) at the 6th month. Serum TPOAb, TgAb, and thyroid echogenicity were unchanged with Se supplementation. A prominent decrease in thyroid volume was noteworthy; 35% of patients showed a thyroid volume regression rate of > or = 30%. In terms of TPOAb and TgAb, Se may not benefit in the euthyroid period of HT, but Se supplementation seems to lead a favorable response in thyroid volume regression.

Selenium and cancer risk in CHEK2 mutation carriers

Checkpoint kinase 2 (CHEK2) is as an important signal transducer of cellular responses to DNA damage and acts as a tumour suppressor gene. Mutations in the CHEK2 gene have been shown to be associated with increased risks to several cancers. In Poland four mutations in CHEK2 gene (1100delC, IVS2+1G>A, I157T, del5395) have been identified. Studies on our population provided evidence that CHEK2 truncating mutations are associated with increased risk of cancer in the thyroid, breast and prostate. The I157T has been found to be associated with increased risk of breast, prostate, colon, kidney and thyroid cancer. The variability in penetrance and cancer expression in mutation carriers probably can be explained by influence of other genetic or environmental factors. Our preliminary data indicate that serum selenium level is associated with breast/ovarian cancer risk in Polish BRCA1 carriers. Both genes, BRCA1 and CHEK2, belong to the same pathway, however clinical presentation of cancer phenotype in carriers of mutation in particular gene is different eg. in respect to cancer location or tumour pathological features. It may suggest presence of distinct genetic factors which modify cancer risk in BRCA1 and CHEK2 carriers. Aim of the study was to check if Se concentration as well as alterations in genes coding selenoproteins can be a risk factors for cancer development in CHEK2 mutation carriers. In this study we will determine serum Se concentration and analyze genes coding selenoproteins in ~100 CHEK2 mutation carriers affected by different cancers (eg. breast, prostate, colon, kidney, lung, larynx) and ~100 unaffected CHEK2 carriers matched to the cancer cases. We analysed for Se concentration and alterations of 13 selenoproteins in 58 CHEK2 carriers constituting 29 pairs, each composed of cancer patient and unaffected control matched by: CHEK2 mutation type (missense or protein truncating), sex, year of birth, smoking status (pack-years +/- 20%) and cancer family history among I° relatives. We observed lower Se concentration in cancer patients than in controls (70.5µg/l vs. 76.8 µg/l), however due to low number of pairs this difference was not statistically significant. We found some evidence that specific genotypes in tested selenoprotein genes may be associated with different cancer risk depending on Se concentration, however this observation has also to be verified in larger number of pairs.

Serum selenium and single-nucleotide polymorphisms in genes for selenoproteins: relationship to markers of oxidative stress in men from Auckland, New Zealand

There is controversy as to the recommended daily intake of selenium (Se), and whether current New Zealand diets are adequate in this nutrient. Various functional single-nucleotide polymorphisms (SNPs) polymorphisms may affect the efficacy of Se utilisation. These include the glutathione peroxidases GPx1 rs1050450, GPx4 rs713041, as well as selenoproteins SEPP1 rs3877899, SEL15 rs5845, SELS rs28665122 and SELS rs4965373. This cross-sectional study measured serum Se levels of 503 healthy Caucasian men in Auckland, New Zealand, between ages 20-81. The Se distribution was compared with activities of the antioxidant enzymes glutathione peroxidase and thioredoxin reductase, and DNA damage as measured by the single cell gel electrophoresis assay, both without and with a peroxide-induced oxidative challenge. Serum Se was measured using inductively coupled plasma-dynamic reaction cell-mass spectrometry, while selenoprotein SNPs were estimated using TaqMan(®) SNP genotyping assays. While antioxidant enzyme activities and DNA damage recorded after a peroxide challenge increased with increasing serum selenium, the inherent DNA damage levels in leukocytes showed no statistically significant relationship with serum selenium. However, these relationships and dietary Se requirements at the individual level were modified by several different SNPs in genes for selenoproteins. The GPx1 rs1050450 C allele was significantly associated with GPx activity. Significant correlations between serum Se level and GPX activity were seen with all genotypes except for homozygous minor allele carriers, while the GPx1 rs1050450 CT genotype showed the highest correlation. Several genotypes showed significant correlations between serum Se and TR activity with SEPP1 rs3877899 GG genotype showing the highest correlation. A significant decreasing trend in DNA damage with increasing serum Se was seen among GPx1 rs1050450 CC and GPx4 rs713041 TT genotype carriers up to a serum Se level of 116 and 149ng/ml, respectively. In the absence of this genetic information, we would recommend a serum Se concentration in the region of 100-150ng/ml as providing a useful compromise.

Effect of sildenafil citrate (Viagra ®) on trace element concentration in serum and brain of rats

As a vasodilator with good hemodynamic effects, sildenafil has been successfully used in the treatment of patients with pulmonary hypertension and cardiovascular diseases. By selectively inhibiting phosphodiestrase type 5 (PDE-5) and thus effectively reducing the breakdown of c GMP, sildenafil administration can markedly improve the erectile dysfunction. Sildenafil also elevates localized cerebral blood flow in rat brain. The objective of the present study was to investigate the effect of sildenafil on the level of trace elements (Zinc (Zn), copper (Cu), iron (Fe), selenium (Se), cobalt (Co), and chromium (Cr)) in blood and brain of rats. Sixteen male albino rats weighing 180–200 g were divided into two groups (8 rats/group). Sildenafil (Viagra, Pfizer Inc.) was dissolved in saline and administered at a dose of 10 mg/kg i.p. (0.5 ml volume) to rats in the treated group every 72 h for 12 injections. Rats in the control group were administered the same volume of saline as in treated group. All rats were sacrificed 24 h after the last injection. Blood samples were collected and serum was separated and stored at −20 °C. Brains were dissected and stored frozen until analysis. Trace elements concentrations were determined by flame emission atomic absorption spectrophotometer. Results showed that sildenafil injection significantly ( P < 0.05) increased serum and brain Se and Cu concentrations. Moreover, sildenafil increased the Cr concentration in the brain tissue. It was concluded that sildenafil citrate administration increased serum Se and Cu as well as, increased brain Se, Cu, and Cr concentrations in rats.

Organic and inorganic selenium: II. Transfer efficiency from ewes to lambs1

Adequate Se transfer from ewes to lambs is important to prevent Se-deficiency diseases. To evaluate how different chemical forms of Se administered at comparative dosages to mature ewes affect Se status of their lambs, 240 ewes were divided into 8 treatment groups (n = 30 each) and drenched weekly (at an amount equal to their summed daily intake) with no-Se (controls); at recommended amounts (4.9 mg of Se/wk) with inorganic Na-selenite, inorganic Na-selenate, or organic Se-yeast; or at supranutritional amounts (14.7 and 24.5 mg of Se/wk) with Na-selenite or Se-yeast for 1 yr. Weekly drenching of Se was effective at increasing (P < 0.002) Se concentrations in ewe colostrum and milk at 30 d of lactation and in improving (P < 0.001) the Se status of lambs (whole-blood and serum-Se concentrations at birth, and skeletal-muscle Se concentrations at 14 d of age). Selenium concentrations in lacteal secretions were greater in ewes drenched with Se-yeast (colostrum: 374, 436, and 982 ng/mL at 4.9, 14.7, and 24.5 mg of Se/wk, respectively; milk: 26, 39, 64 ng/mL) compared with ewes drenched with Na-selenite (colostrum: 204, 334, 428 ng/mL; milk: 16, 21, 24 ng/mL), and were also greater (P < 0.001) in their lambs. Selenium concentrations continued to increase (P < 0.001) in lamb whole blood (558 and 695 ng/mL at 14.7 and 24.5 mg of Se/wk, respectively), serum (126, 183 ng/mL), and skeletal muscle (991, 1,696 ng/mL) with supranutritional concentrations of Se-yeast, whereas Se concentrations did not differ in whole blood (304, 332 ng/mL), serum (77, 85 ng/mL), or skeletal muscle (442, 482 ng/mg) of lambs from ewes drenched with 14.7 or 24.5 mg of Se/wk of Na-selenite. We conclude that weekly oral drenching of ewes during gestation and lactation with organic Se-yeast results in a more efficient transfer of Se (over a wide range of supplementation rates) from ewe to lamb than does inorganic Na-selenite.

Organic and inorganic selenium: I. Oral bioavailability in ewes1

Although the essentiality of dietary Se for sheep has been known for decades, the chemical source and Se dosage for optimal health remain unclear. In the United States, the Food and Drug Administration (FDA) regulates Se supplementation, regardless of the source of Se, at 0.3 mg of Se/kg of diet (as fed), which is equivalent to 0.7 mg of Se/d or 4.9 mg of Se/wk per sheep. The objectives of this study were to evaluate the effects of Se source (inorganic vs. organic) and supplementation rate (FDA vs. supranutritional rates of 14.7 and 24.5 mg of Se/wk) on whole-blood (WB) and serum-Se concentrations. Mature ewes (n = 240) were randomly assigned to 8 treatment groups (n = 30 each) based on Se supplementation rate (4.9, 14.7, and 24.5 mg of Se•wk(-1)•sheep(-1)) and source [Na-selenite, Na-selenate (4.9 mg/wk only), and organic Se-yeast] with a no-Se control group (0 mg of Se/wk). Treatment groups were balanced for healthy and footrot-affected ewes. For 1 yr, ewes were individually dosed once weekly with 0, 4.9, 14.7, or 24.5 mg of Se, quantities equivalent to their summed daily supplementation rates. Serum- and WB-Se concentrations were measured every 3 mo in all ewes; additionally, WB-Se concentrations were measured once monthly in one-half of the ewes receiving 0 or 4.9 mg of Se/wk. Ewes receiving no Se showed a 78.8 and 58.8% decrease (P < 0.001) in WB- (250 to 53 ng/mL) and serum- (97 to 40 ng/mL) Se concentrations, respectively, over the duration of the study. Whole-blood Se decreased primarily during pregnancy (-57%; 258 to 111 ng/mL) and again during peak lactation (-44%; 109 to 61 ng/mL; P < 0.001). At 4.9 mg of Se/wk, Se-yeast (364 ng/mL, final Se concentration) was more effective than Na-selenite (269 ng/mL) at increasing WB-Se concentrations (P < 0.001). Supranutritional Se-yeast dosages increased WB-Se concentrations in a dose-dependent manner (563 ng/mL, 14.7 mg of Se/wk; 748 ng/mL, 24.5 mg of Se/wk; P < 0.001), whereas WB-Se concentrations were not different for the Na-selenite groups (350 ng/mL, 14.7 mg of Se/wk; 363 ng/mL, 24.5 mg of Se/wk) or the 4.9 mg of Se/wk Se-yeast group (364 ng/mL). In summary, the dose range whereby Se supplementation increased blood Se concentrations was more limited for inorganic Na-selenite than for organic Se-yeast. The smallest rate (FDA-recommended quantity) of organic Se supplementation was equally effective as supranutritional rates of Na-selenite supplementation in increasing WB-Se concentrations, demonstrating the greater oral bioavailability of organic Se.