Selenium

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Selenium

  • elemental selenium
  • inorganic selenium
  • serum selenium

  • Terms modified by Selenium

  • selenium atom
  • selenium compound
  • selenium concentration
  • selenium deficiency
  • selenium dioxide
  • selenium level
  • selenium metabolism
  • selenium status
  • selenium supplementation

  • Selected Abstracts


    MODULATION OF VERY-LONG CHAIN (C28) HIGHLY UNSATURATED FATTY ACIDS IN PROROCENTRUM MININUM (DINOPHYCEAE) BY SELENIUM

    JOURNAL OF PHYCOLOGY, Issue 2000
    A. Place
    Recently, very-long-chain (C28) highly unsaturated fatty acids (VLC-HUFA) were identified in seven marine dinoflagellate species (Manour et al., Phytochemistry, 1999, 50: 541,548). In general, the proportion of these fatty acids accounted for less than 2.3% of the total fatty acids in these species. As part of a study investigating the modulation of the hemolytic fatty acid 18:5n3, cultures of Prorocentrum mininum were grown in artificial seawater with varying molarities of sodium selenite (0, 1, 10, and 100 nM). Optimal growth was observed at 1 nM with this media. As expected, the level of 18:5n3 was modulated by the selenium in the culture medium (7.0 ± 0.2, 14.5 ± 0.6, 7.4 ± 0.8, and 3.9 ± 0.8% of total fatty acid, respectively), with the highest percentage found at 1 nM. Unexpectedly the level of VLC-HUFA (28:8n3) increased to 7.3 ± 2.8% at 0 nM sodium selenite, while at all other selenite concentrations the VLC-HUFA was less than 1%. A possible biochemical basis for this finding will be discussed. [source]


    Development of a Novel Automatic Potentiometric System for Determination of Selenium and Its Application in Pharmaceutical Formulations and Anodic Slime

    ELECTROANALYSIS, Issue 9 2008
    Ayman
    Abstract Poly(vinyl chloride) polymeric membrane sensors containing Sn(IV) phthalocyanine dichloride (SnPC) and Co(II) phthalocyanine (CoPC) as novel electroactive materials dispersed in o -nitrophenyl octylether (o -NPOE) as a plasticizer are examined potentiometrically with respect to their response toward selenite (SeO32,) ions. Fast Nernstian response for SeO32, ions over the concentration ranges 7.0×10,6,1.0×10,3 and 8.0×10,6,1.0×10,3 mol L,l at pH,3.5,8.5 with lower detection limit of 5.0×10,6 and 8.0×10,6 mol L,1 and calibration slopes of ,25.4 and ,29.7,mV decade,1 are obtained with SnPC and CoPC based membrane sensors, respectively. The proposed sensors reveals by the modified separate solution method (MSSM) a good selectivity over different anions which differ significantly from the classical Hofmeister series. A segmented sandwich membrane method is used to determine complex formation constants of the ionophores in situe in the solvent polymeric sensing membranes. Membrane incorporating CoPC in a tubular flow detector is used in a two channels flow injection set up for continuous monitoring of selenite at a frequency of ca. 50 samples h,1. Direct determination of selenium in pharmaceutical formulations and anodic slime gives results in good agreement with data obtained using standard ICP method. [source]


    Heavy Metals in Matrices of Food Interest: Sequential Voltammetric Determination at Trace and Ultratrace Level of Copper, Lead, Cadmium, Zinc, Arsenic, Selenium, Manganese and Iron in Meals

    ELECTROANALYSIS, Issue 18 2004
    Clinio Locatelli
    Abstract The voltammetric methods are very suitable and versatile techniques for the simultaneous metal determination in complex matrices. The present work, regarding the sequential determination of Cu(II), Pb(II), Cd(II), Zn(II) by square-wave anodic stripping voltammetry (SWASV), As(III), Se(IV) by square-wave cathodic stripping voltammetry (SWCSV) and Mn(II), Fe(III) by square-wave voltammetry (SWV) in matrices involved in foods and food chain as wholemeal, wheat and maize meal, are an interesting example of the possibility to sequentially determine each single element in real samples. Besides the set up of the analytical method, particular attention is aimed either at the problem of possible signal interference or to show that, using the peak area Ap as instrumental datum, it is possible to achieve lower limits of detection. The analytical procedure was verified by the analysis of the standard reference materials: Wholemeal BCR-CRM 189, Wheat Flour NIST-SRM 1567a and Rice Flour NIST-SRM 1568a. Precision, as repeatability, and accuracy, expressed as relative standard deviation and relative error, respectively, were lower than 6% in all cases. In the presence of reciprocal interference, the standard addition method considerably improved the resolution of the voltammetric technique. Once set up on the standard reference materials, the analytical procedure was transferred and applied to commercial meals sampled on market for sale. A critical comparison with spectroscopic measurements is also discussed. [source]


    Selenium and mercury concentrations in California gulls breeding on the Great Salt Lake, Utah, USA

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 2 2009
    Michael R. Conover
    Abstract We examined selenium (Se) and mercury (Hg) concentrations in adult California gulls (Larus californicus) nesting on the Great Salt Lake, Utah, USA, during 2006 and 2007. During 2006, the mean Se concentration (± standard error) was 18.1 ± 1.5 ,g/g in blood on a dry-weight basis and 8.1 ± 0.4 ,g/g in liver. During 2007, Se concentrations were 15.7 ± 1.5 ,g/g in blood and 8.3 ± 0.4 ,g/g in liver; Hg concentrations were 2.4 ± 0.3 ,g/g in blood and 4.1 ± 0.5 ,g/g in liver. Gulls collected from a freshwater colony located within the watershed of the Great Salt Lake had similar levels of Se in the blood and liver as gulls collected on the Great Salt Lake but lower Hg concentrations. Body mass of adult gulls was not correlated with Se or Hg concentrations in their blood or liver. Selenium concentration in California gull eggs collected during 2006 was 3.0 ± 0.10 ,g/g. Of 72 eggs randomly collected from Great Salt Lake colonies, only one was infertile, and none of the embryos exhibited signs of malposition or deformities. We examined 100 newly hatched California gull chicks from Great Salt Lake colonies for teratogenesis; all chicks appeared normal. Hence, the elevated Se and Hg concentrations in adult gulls nesting on the Great Salt Lake did not appear to impair gulls' health or reproductive ability. [source]


    Polycyclic aromatic hydrocarbons, aliphatic hydrocarbons, trace elements, and monooxygenase activity in birds nesting on the North Platte River, Casper, Wyoming, USA

    ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 3 2001
    Thomas W. Custer
    Abstract Tree swallow (Tachycineta bicolor) and house wren (Troglodytes aedon) eggs and chicks were collected near a refinery site on the North Platte River, Casper, Wyoming, USA and at a reference site 10 km upstream. Total polycyclic aromatic hydrocarbon (PAH) concentrations in swallow and wren chicks were higher at the refinery site than at the reference site. Polycyclic aromatic hydrocarbon concentrations in sediment and chick dietary samples were consistent with these findings. The general lack of methylated PAHs in sediment, diet, and bird carcasses suggested that the PAHs were derived from combustion and not from petroleum. The predominance of odd-numbered aliphatic hydrocarbons and the low ratios (,0.25) of pristane:n -C17 and phytane:n -C18 in chick and diet samples also suggested that swallow and wren chicks were not being chronically exposed to petroleum. Mean ethoxyresorufin- O -dealkylase and benzyloxyresorufin- O -dealkylase activities in tree swallow livers averaged nine times higher at the refinery site than at the reference site and were probably induced by exposure to PAHs. Trace element concentrations in eggs and livers of swallows and wrens were similar or greater at the reference site than at the refinery site. Selenium, strontium, and boron concentrations were elevated in eggs and livers of swallows and wrens at both the refinery and reference sites. [source]


    Synthesis and Structure Determination of Selenium(IV) Cyanides

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 30 2008
    Stefanie Fritz
    Abstract The reaction of SeF4 with Me3SiCN did not result in thepreparation of the designated Se(CN)4 but Se(CN)F3 and Se(CN)2F2 were obtained as first known selenium(IV)cyanide compounds and characterized by their NMR spectra. Se(CN)2F2 was crystallized as 1,2-dimethoxyethane solvate as well as the corresponding tellurium compound Te(CN)2F2 with very similar structures. NMR spectroscopic data of some more miscellaneous tellurium cyanides and the crystal structures of solvates of Se(CN)2 and oxygen-bridged TeO(CN)2 are presented. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source]


    Novel 1,2-Dicarba- closo -dodecaborane(12) Derivatives of Selenium

    EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2007
    Bernd Wrackmeyer
    Abstract Lithiation of 1,2-dicarba- closo -dodecaborane(12) (1) followed by insertion of selenium into both C,Li bonds leads to the 1,2-diselenolato-1,2-dicarba- closo -dodecaborane(12) dianion (3), which is converted by oxidative coupling into the cyclic eight-membered bis(diselane) 4 with annellated carborane moieties. Oxidative addition of 4 to ethenebis(triphenylphosphane)platinum(0) gives the bis(triphenylphosphane)platinum(II) complex 7, which contains a chelating 1,2-diselenolato-1,2-dicarba- closo -dodecaborane(12) ligand, by symmetric cleavage of the eight-membered ring in 4 and displacement of ethene. The molecular structures of 4 and 7 were determined by X-ray analysis. The solution-state structures of the new compounds are supported by multinuclear NMR data (1H, 11B, 13C, 29Si, 31P, 77Se, 195Pt). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source]


    Selenium affects biosilica formation in the demosponge Suberites domuncula

    FEBS JOURNAL, Issue 15 2005
    Effect on gene expression, spicule formation
    Selenium is a trace element found in freshwater and the marine environment. We show that it plays a major role in spicule formation in the demosponge Suberites domuncula. If added to primmorphs, an in vitro sponge cell culture system, it stimulates the formation of siliceous spicules. Using differential display of transcripts, we demonstrate that, after a 72-h exposure of primmorphs to selenium, two genes are up-regulated; one codes for selenoprotein M and the other for a novel spicule-associated protein. The deduced protein sequence of selenoprotein M (14 kDa) shows characteristic features of metazoan selenoproteins. The spicule-associated protein (26 kDa) comprises six characteristic repeats of 20 amino acids, composed of 10 distinct hydrophobic regions (, 9 amino acids in length). Recombinant proteins were prepared, and antibodies were raised against these two proteins. Both were found to stain the central axial filament, which comprises the silicatein, as well as the surface of the spicules. In the presence of selenium, only the genes for selenoprotein M and spicule-associated protein are up-regulated, whereas the expression of the silicatein gene remains unchanged. Finally we show that, in the presence of selenium, larger silica aggregates are formed. We conclude that selenium has a stimulatory effect on the formation of siliceous spicules in sponges, and it may be involved in the enzymatic synthesis of biosilica components. [source]


    Selenium and vitamin E supplements do not prevent prostate cancer: the importance of prospective RCTs for definitive practice guidelines

    FOCUS ON ALTERNATIVE AND COMPLEMENTARY THERAPIES AN EVIDENCE-BASED APPROACH, Issue 3 2009
    Article first published online: 3 JUN 2010
    [source]


    Selenium metabolism in zebrafish: multiplicity of selenoprotein genes and expression of a protein containing 17 selenocysteine residues

    GENES TO CELLS, Issue 12 2000
    Gregory V. Kryukov
    Fish are an important source of selenium in human nutrition and the zebrafish is a potentially useful model organism for the study of selenium metabolism and its role in biology and medicine. Selenium is present in vertebrate proteins in the form of selenocysteine (Sec), the 21st natural amino acid in protein which is encoded by UGA. We report here the detection of 18 zebrafish genes for Sec-containing proteins. We found two zebrafish orthologs of human SelT, glutathione peroxidase 1 and glutathione peroxidase 4, and single orthologs of several other selenoproteins. In addition, new zebrafish selenoproteins were identified that were distant homologues of SelP, SelT and SelW, but their direct orthologs in other species are not known. This multiplicity of selenoprotein genes appeared to result from gene and genome duplications, followed by the retention of new selenoprotein genes. We found a zebrafish selenoprotein P gene (designated zSelPa) that contained two Sec insertion sequence (SECIS) elements and encoded a protein containing 17 Sec residues, the largest number of Sec residues found in any known protein. In contrast, a second SelP gene (designated zSelPb) was also identified that contained one SECIS element and encoded a protein with a single Sec. We found that zSelPa could be expressed and secreted by mammalian cells. The occurrence of zSelPa and zSelPb suggested that the function of the N-terminal domain of mammalian SelP proteins may be separated from that of the C-terminal Sec-rich sequence: the N-terminal domain containing the UxxC motif is likely involved in oxidoreduction, whereas the C-terminal portion of the protein may function in selenium transport or storage. Our data also suggest that the utilization of Sec is more common in zebrafish than in previously characterized species, including mammals. [source]


    Determination of Selenium Concentration in Sixty Five Reference Materials for Geochemical Analysis by GFAAS after Separation with Thiol Cotton

    GEOSTANDARDS & GEOANALYTICAL RESEARCH, Issue 2-3 2001
    Luc Marin
    sélénium; SAA four graphite; séparation; matériaux géologiques de référence; coton thiol Selenium has been determined in sixty five geological reference materials of different origins by graphite furnace atomic absorption spectrometry. Samples were decomposed with a mixture of nitric and hydrofluoric acids. Selenium was reduced to SeIV with hydrochloric acid, and then fixed and separated from the matrix on thiol cotton. After digestion of the thiol cotton in hot nitric acid, the Se concentration was measured using palladium and magnesium nitrates as a matrix modifier. The limit of determination was 0.02 ,g g,1, the precision of the results (relative standard deviation of 3 to 8 replicates) varied from 2.6 to 17.7% with an average of 7.9% in the range 0.02-42.7 ,g g,1 and was similar to the value obtained for synthetic samples. Our results are in good agreement with available literature values. Le sélénium a été dosé sur 65 standards géochimiques de référence de différentes provenances par spectrométrie d'absorption atomique avec four graphite. Les échantillons ont été mis en solution par une attaque acide HNO3 -HF. Le sélénium a été réduit en SeIV avec de l'acide chlorhydrique, fixé et séparé de la matrice sur du coton thiol. Après décomposition du coton thiol par chauffage avec de l'acide nitrique, les concentrations en sélénium ont été mesurées en utilisant du nitrate de palladium et de magnésium comme modificateur de matrice. La limite de détermination est de 0.02 ,g g,1, la précision des résultats (écart type relatif sur 3 à 8 mesures) pour les standards géochimiques varie de 2.6 à 17.7% avec une moyenne de 7.9% dans la game 0.02-42.7 ,g g,1et est comparable à celle obtenue pour des échantillons synthétiques. Nos résultats sont en bonne concordance avec les résultats déjà publiés dans la littérature. [source]


    Selenium: When a good nutrient goes bad

    INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 3 2009
    Peter M. Chapman Golder Associates
    No abstract is available for this article. [source]


    Selenium effects: A weight-of-evidence approach

    INTEGRATED ENVIRONMENTAL ASSESSMENT AND MANAGEMENT, Issue 1 2007
    Blair G McDonald
    Abstract Selenium is increasingly an issue for a wide range of mining, industrial, and agricultural operations. Appropriate methods for evaluating the impacts of selenium in aquatic ecosystems are vigorously debated in the literature. Two common approaches include the use of tissue residue guidelines and reproductive toxicity testing using field-collected fish; however, each approach on its own does not provide sufficient evidence that wild fish populations are in fact impaired. The limitations of each method are discussed, and recommendations to improve the relevance of each line of evidence are provided. A 3rd line of evidence, field measurement of fish population dynamics, is proposed and also discussed. A framework, consistent with an ecological risk assessment methodology, for the design, application, and interpretation of selenium weight-of-evidence investigations is proposed. [source]


    Enzymatic and immunochemical evaluation of phospholipid hydroperoxide glutathione peroxidase (PHGPx) in testes and epididymal spermatozoa of rats of different ages

    INTERNATIONAL JOURNAL OF ANDROLOGY, Issue 2 2002
    Federica Tramer
    Selenium (Se) and selenoproteins such as glutathione peroxidases are necessary for the proper development and fertilizing capacity of sperm cells. Phospholipid hydroperoxide glutathione peroxidase (PHGPx, E.C. 1.11.1.12) is a monomeric seleno-enzyme present in different mammalian tissues in soluble and bound form. Its function, like the other glutathione peroxidases, was originally viewed as a protective role against hydroperoxides, but direct and indirect evidence indicates that it has additional regulatory roles. PHGPx is present in testis cells and sperm cells, and its appearance is hormone regulated. We present here biochemical data, which clearly indicate that the enzyme specific activity in rat is age-dependent during the life-span monitored (from 36 to 365 days), with a maximum at 3 months of age in the testis germ cells and at 6 months of age in the isolated epididymal sperm cells. Western blotting and immunocytochemical analysis by means of anti-PHGPx antibodies show the different distribution and the strong binding of PHGPx in the testes and sperm cell subcellular compartments (nucleus, acrosome, mitochondria and residual bodies) of rats of different age. The presence of the protein exhibits in the testis cells a pattern different from that of the catalytic activity, with a maximum at 6 months of age. The subcellular distribution of PHGPx is qualitatively, but not quantitatively, unchanged during ageing. These different behaviours are compared and discussed. [source]


    Toenail selenium and risk of hepatocellular carcinoma mortality in Haimen City, China,

    INTERNATIONAL JOURNAL OF CANCER, Issue 4 2005
    Lori C. Sakoda
    Abstract Selenium (Se) is an essential trace mineral with known anticarcinogenic properties in humans. However, few studies have examined the association between Se nutrient status and risk of liver cancer. We conducted a nested case-control study comparing the Se content in toenail clippings of 166 individuals (154 men, 12 women) with hepatocellular carcinoma (HCC) to 394 healthy controls (360 men, 34 women) in Haimen City, China, where HCC is a leading cause of mortality. Toenail Se concentration was measured by inductively coupled plasma-optical emission spectroscopy. Median toenail Se was lower for HCC cases than controls (p = 0.03). Adjusted odds ratios and 95% confidence intervals for HCC mortality by increasing quartile of toenail Se were 1.00 (reference), 0.58 (0.32,1.03), 0.83 (0.48,1.42) and 0.50 (0.28,0.90), with a marginally significant trend in risk observed (p for trend = 0.06). This inverse association appeared stronger among those who did not consume alcohol and among women. Future studies are needed to examine the interrelationship between Se, viral hepatitis infection and HCC in order to better understand the etiologic mechanisms involved and evaluate the true chemopreventive potential of Se compounds for liver diseases. © 2005 Wiley-Liss, Inc. [source]


    Selenium-Based Glasses and Glass Ceramics Transmitting Light from the Visible to the Far-IR

    ADVANCED MATERIALS, Issue 1 2007
    L. Calvez
    An innovative glass/glass ceramic based on the GeSe2,Ga2Se3,CsCl system is reported. This material is the first reported glass/glass ceramic transparent from the visible to the far-IR, has improved mechanical properties over selenide glasses, and is compatible with high-precision molding, making it suitable for applications in thermal imaging. [source]


    SELECT shows no effect on prostate cancer prevention

    INTERNATIONAL JOURNAL OF UROLOGICAL NURSING, Issue 1 2009
    Lawrence Drudge-Coates
    Abstract To determine whether selenium, vitamin E, or both could prevent prostate cancer and other diseases with little or no toxicity in relatively healthy men. Oral selenium (200 ,g/d from L -selenomethionine) and matched vitamin E placebo, vitamin E (400 IU/d of all rac-, -tocopheryl acetate) and matched selenium placebo, selenium + vitamin E, or placebo + placebo for a planned follow-up of minimum of 7 years and a maximum of 12 years. Number of men diagnosed with prostate cancer and prespecified secondary outcomes, including lung, colorectal, and overall primary cancer. Selenium or vitamin E, alone or in combination at the doses and formulations used, did not prevent prostate cancer in this population of relatively healthy men. [source]


    Selenium supplementation and selenium status of dairy cows fed diets based on grass, grass silage or maize silage

    JOURNAL OF ANIMAL PHYSIOLOGY AND NUTRITION, Issue 3-4 2002
    M. GIERUS
    In three separate trial series (TS) the effect of diet composition on selenium (Se) status of dairy cows were investigated. Diets were formulated based mainly on grass (TS1), grass silage (TS2) or maize silage (TS3) with different levels of Se supplementation. Each TS comprised a total of 30 dairy cows and contained one treatment group without Se supplementation (control) and two groups with increasing levels of Se supplementation (levels 1 and 2). Selenium was administered as Na-selenite. The control groups of the different TS showed a very low Se supply of 38,54 ,g Se/kg DM. At level 1 the Se supply was increased to 102,165 ,g Se/kg DM and at level 2 was 294,373 ,g Se/kg DM. After completion of the 6-week trials the average plasma Se concentration of the control cows (without Se supplementation) across all TS was 21.5 ,g/l; this increased significantly following Se supplementation, to 37.7 ,g/l at level 1 and 61.5 ,g/l at level 2. The plasma glutathione peroxidase (GSH-Px) activity of the control cows averaged 67 U/l, rising considerably after supplementation at level 1 to a value of 101 U/l, but showed little further increase at level 2 with a mean value of 120 U/l. By contrast, the average Se content of the milk was unchanged in the control and level 1 groups at 10.5 ,g/kg and 10.9 ,g/kg, respectively, and only increased markedly after supplementation at level 2 to a mean value of 15.1 ,g/kg. The diet based on maize silage, while having a similar Se content as the grass and grass silage-based diets, resulted in a slightly improved Se status, which is due to a higher Se intake from soybean meal. [source]


    Effects of Vitamin E and Organic Selenium on Oxidative Stability of ,-3 Enriched Dark Chicken Meat during Cooking

    JOURNAL OF FOOD SCIENCE, Issue 2 2010
    T.I. Perez
    ABSTRACT:, The influence of vitamin E and selenomethionine (SeMet) on lipid oxidation in frozen,raw and cooked ,-3 enriched dark chicken meat was evaluated. Feed was supplemented with 2 levels of vitamin E (250 and 50 IU/kg of feed) and selenium (0.1 mg of sodium selenite/kg of feed and 0.3 mg of SeMet/kg of feed). An extruded linseed product was used as the ,-linolenic acid source. Fatty acid (FA) profile, oxysterols, and thiobarbituric reactive acid substances (TBARs) were analyzed in frozen,raw, boiled, pan-fried, and roasted meat. After 6 mo of storage, oxysterols in frozen,raw meat remained stable with either high or low levels of dietary antioxidants. During cooking, high levels of vitamin E reduced oxysterol formation, whereas high levels of SeMet were inconsistent and even increased oxysterols during roasting. TBARs in frozen,raw meat stored for 6 mo were inhibited by high levels of either antioxidant. Conversely, no protective effect during cooking was observed at this time of storage. After 12 mo at ,30 °C no antioxidant protection was observed. [source]


    Selenium and selenoproteins in the brain and brain diseases

    JOURNAL OF NEUROCHEMISTRY, Issue 1 2003
    Jun Chen
    Abstract Over the past three decades, selenium has been intensively investigated as an antioxidant trace element. It is widely distributed throughout the body, but is particularly well maintained in the brain, even upon prolonged dietary selenium deficiency. Changes in selenium concentration in blood and brain have been reported in Alzheimer's disease and brain tumors. The functions of selenium are believed to be carried out by selenoproteins, in which selenium is specifically incorporated as the amino acid, selenocysteine. Several selenoproteins are expressed in brain, but many questions remain about their roles in neuronal function. Glutathione peroxidase has been localized in glial cells, and its expression is increased surrounding the damaged area in Parkinson's disease and occlusive cerebrovascular disease, consistent with its protective role against oxidative damage. Selenoprotein P has been reported to possess antioxidant activities and the ability to promote neuronal cell survival. Recent studies in cell culture and gene knockout models support a function for selenoprotein P in delivery of selenium to the brain. mRNAs for other selenoproteins, including selenoprotein W, thioredoxin reductases, 15-kDa selenoprotein and type 2 iodothyronine deiodinase, are also detected in the brain. Future research directions will surely unravel the important functions of this class of proteins in the brain. [source]


    Increased intakes of selenium-enriched foods may benefit human health

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2007
    John Weldon Finley
    Abstract Selenium is an essential nutrient and deficient intakes compromise health in domestic animals and humans. A recommended dietary allowance (RDA) of 55 µg d,1 has been set for adult males and females in the United States; most North Americans consume more than this amount, but many residents of Europe, Asia and Africa consume less. While there are very few reports of outright Se deficiency in people consuming mixed Western diets that have Se intakes below the RDA, there is evidence that dietary intakes of selenium greater than the requirement may help reduce the risk of cancer, especially prostate cancer, to men. Selenium metabolism depends on the chemical form of Se in the diet, and some forms are better for some actions (e.g., cancer reduction) than other forms. Foods may contain different amounts and chemical forms of Se; consequently the benefits of Se may depend on the particular foods consumed. There are many reports of the chemistry and health benefits of Se from plant foods; animal foods also contain Se, but there are fewer reported studies. Fully understanding the health benefits of Se that may be gained by consumption of Se-enriched foods will require multidisciplinary approaches by teams of medical researchers, chemists, nutritionists, and agricultural scientists. Copyright © 2007 Society of Chemical Industry [source]


    Sodium selenate fertilisation increases selenium accumulation and decreases glucosinolate concentration in rapid-cycling Brassica oleracea

    JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2001
    Craig S Charron
    Abstract Glucosinolates (GSs) are S-containing compounds found in Brassica species and whose degradation products may provide protection against cancer. Sulphoraphane, a product of 4-methylsulphinylbutyl GS degradation, is a particularly potent inhibitor of anticarcinogenic detoxification enzymes. Selenium also has anticancer properties, and consumption of plants containing Se may be an effective way to increase dietary Se. Since plant uptake of Se and S is competitive, GS synthesis may be affected by Se fertilisation. The objective of this study was to determine how Se fertilisation of rapid-cycling B oleracea would affect Se and GS concentrations. Plants were grown in hydroponic solutions containing 0.0, 1.0, 2.0, 3.0, 6.0, 7.2 or 9.0,mg,l,1 Na2SeO4. Mineral and glucosinolate concentrations were measured in shoots harvested just before anthesis. Total GSs decreased from 5.84,µmol,g,1 (0.0,mg,l,1 Na2SeO4) to 1.90,µmol,g,1 (9.0,mg,l,1Na2SeO4). Levels of 4-methylsulphinylbutyl GS decreased 90% when Na2SeO4 fertilisation was increased from 0 to 1,mg,l,1, and remained low at higher Na2SeO4 concentrations. Shoot Se concentration was undetectable at 0.0,mg,l,1 Na2SeO4 and increased significantly with Na2SeO4 fertilisation. Although B oleracea may not simultaneously deliver high levels of dietary 4-methylsulphinylbutyl GS and Se, levels of other GSs with anticarcinogenic benefits may be beneficial even with Se fertilisation. © 2001 Society of Chemical Industry [source]


    Selenium attenuates pro-inflammatory gene expression in macrophages

    MOLECULAR NUTRITION & FOOD RESEARCH (FORMERLY NAHRUNG/FOOD), Issue 11 2008
    Hema Vunta
    Abstract Selenium (Se) is an important element required for the optimal functioning of the immune system. Particularly in macrophages, which play a pivotal role in immune regulation, Se acts as a major antioxidant in the form of selenoproteins to mitigate the cytotoxic effects of reactive oxygen species. Here we describe the role of Se as an anti-inflammatory agent and its effect on the macrophage signal transduction pathways elicited by bacterial endotoxin, LPS. Our studies demonstrate that supplementation of Se to macrophages (Se-deficient) leads to a significant decrease in the LPS-induced expression of two important pro-inflammatory genes, cyclooxygenase-2 (COX-2) and tumor necrosis factor-, (TNF-,) via the inhibition of MAP kinase pathways. Furthermore, Se-deficiency in mice exacerbated the LPS-mediated infiltration of macrophages into the lungs suggesting that Se status is a crucial host factor that regulates inflammation. In summary, our results indicate that Se plays an important role as an anti-inflammatory agent by tightly regulating the expression of pro-inflammatory genes in immune cells. [source]


    Seasonal fluctuations of selenium and sulfur accumulation in selenium hyperaccumulators and related nonaccumulators

    NEW PHYTOLOGIST, Issue 3 2007
    Miriam L. Galeas
    Summary ,,Some plants hyperaccumulate selenium (Se) up to 1% of dry weight. This study was performed to obtain insight into whole-plant Se fluxes in hyperaccumulators. ,,Selenium hyperaccumulators Astragalus bisulcatus and Stanleya pinnata were monitored over two growing seasons for seasonal fluctuations in concentrations of Se and the chemically similar element sulfur (S). The related nonhyperaccumulators Astragalus sericoleucus, Oxytropis sericea and Thlaspi montanum were included for comparison. ,,In both hyperaccumulators leaf Se decreased from April to October, coinciding with Se hyperaccumulation in flowers and seeds. Root Se levels were lowest in summer. Selenium concentration decreased with leaf age in both hyperaccumulators. Leaf S levels peaked in summer in all plant species, as did Se levels in nonhyperaccumulators. Selenium and S levels tended to be negatively correlated in hyperaccumulators, and positively correlated in nonhyperaccumulators. ,,These results suggest a specific flow of Se in hyperaccumulator plants over the growing season, from root to young leaves in spring, followed by remobilization from aging leaves to reproductive tissues in summer, and back to roots in the autumn. [source]


    The Comparative Impact of Iron, the B-Complex Vitamins, Vitamins C and E, and Selenium on Diarrheal Pathogen Outcomes Relative to the Impact Produced by Vitamin A and Zinc

    NUTRITION REVIEWS, Issue 5 2007
    Kurt Z. Long PhD
    Micronutrient supplementation offers one of the most cost-effective means of improving the health and survival of children in developing countries. However, the effects of supplementation with single micronutri-ents on diarrhea are not always consistent, and supplementation with multi-micronutrient supplements can have negative effects. These inconsistencies may result from the failure to consider the diverse etiolog-ical agents that cause diarrhea and the unique effects each micronutrient has on the immune response to each of these agents. This review examines the separate effects that supplementation with the B-complex vitamins, vitamin C, vitamin E, selenium, and iron have on diarrheal disease-related outcomes. Supplementation with iron may increase the risk of infection by invasive diarrheal pathogens, while supplementation with the remaining micronutrients may reduce this risk. These differences may be due to distinct regulatory effects each micronutrient has on the pathogen-specific immune response, as well as on the virulence of specific pathogens. The findings of these studies suggest that micronutrient supplementation of children must take into account the pathogens prevalent within communities as reflected by their diarrheal disease burdens. The effectiveness of combining multiple micronutrients into one supplement must also be reconsidered. [source]


    Selenium Accumulation in Plant Foods

    NUTRITION REVIEWS, Issue 6 2005
    John W. Finley PhD
    Selenium (Se) is an essential nutrient, and Se deficiency is associated with disease conditions and general impairment of the immune system. Supplementation of Se to humans already consuming the RDA may help to prevent certain cancers. A convincing argument can be made for augmenting the food supply with Se, and Se-enhanced plants may be the best means of accomplishing this. Plants accumulate varying amounts of Se in different chemical forms; some plants accumulate Se in direct relationship to the amount available from the soil, whereas others (Se-accumulators) may accumulate Se in concentrations many orders of magnitude above that in the soil. There are many different chemical forms of Se in plants, and the form partially dictates the metabolism of Se by the animal that consumes the plant. The Se content and the chemical form of Se withinplants may be altered by manipulation of plant genetics or by agricultural production conditions. However, attempts to maximize Se in plants may have unintended consequences and must be carefully monitored. [source]


    New Approaches to Assess Selenium Status and Requirement

    NUTRITION REVIEWS, Issue 12 2000
    Jean Nève Ph.D.
    Selenium is one of the essential nutrients that may have beneficial effects on health at dietary intakes higher than the established Recommended Dietary Allowances in the United States. Dietary recommendations for this element have been the subject of much controversy, illustrating the difficulties involved in the definition of requirements based on the interpretation of biochemical markers. This review will show how concepts may differ and even change as a consequence of the evolution of the knowledge concerning classical parameters (e.g., identification of isoforms of the classical selenium-dependent enzyme glutathione peroxidase) or following the discovery of new biologic markers for selenium such as iodothyronine desiodinase, thioredoxin reductase, or the selenoproteins P and W. [source]


    Selenium improves the antioxidant ability against aluminium-induced oxidative stress in ryegrass roots

    ANNALS OF APPLIED BIOLOGY, Issue 2 2010
    P. Cartes
    We investigated the role of selenium (Se) against aluminium (Al) stress in ryegrass by evaluating the growth responses and the antioxidant properties of plants cultured hydroponically with Al (0 or 0.2 mM) and selenite (0,10 µM Se). Al addition significantly reduced the yield and length of shoots and roots, and most Al was accumulated in the roots. Al also enhanced lipid peroxidation and activated the peroxidase (POD), ascorbate peroxidase (APX) and superoxide dismutase (SOD) enzymes in the roots. Se application up to 2 µM improved root growth and steadily decreased thiobarbituric acid reactive substances (TBARS) accumulation in plants treated with 0 and 0.2 mM Al. However, above 2 µM, Se induced stress in plants grown with or without Al. Significant changes in antioxidant enzymes activities were also found as a result of the added Se. At low Se addition levels POD was activated, whereas APX activity decreased irrespective of added Al. Furthermore, Se supplied up to 2 µM greatly decreased root SOD activity in Al-stressed plants. Our study provides evidence that Se alleviated the Al-induced oxidative stress in ryegrass roots through the enhancement of the spontaneous dismutation of superoxide radicals and the subsequent activation of POD enzyme. [source]


    Production and detoxification of H2O2 in lettuce plants exposed to selenium

    ANNALS OF APPLIED BIOLOGY, Issue 1 2009
    J.J. Ríos
    Abstract Selenium is considered an essential element for animals. Despite that it has not been demonstrated to be essential for higher plants, it has been attributed with a protective role against reactive oxygen species in plants subjected to stress. In this study, lettuce plants (Lactuca sativa cv. Philipus) received different application rates (5, 10, 20, 40, 60, 80 and 120 ,M) of selenite or selenate, with the aim of testing the effect of Se on the production and detoxification of H2O2 in non-stressed plants. The results indicate that the form selenate is less toxic than selenite; that is, the plants tolerated and responded positively to this element, and even increasing in growth up to a rate of 40 ,M for the form selenate. On the contrary, the application of selenite triggered a higher foliar concentration of H2O2 and a higher induction of lipid peroxidation [malondialdehyde content and lipoxygenase activity] in comparison to that observed after the selenate application. Also, the plants treated with selenate induced higher increases in enzymes that detoxify H2O2, especially ascorbate peroxidase and glutathione (GSH) peroxidase, as well as an increase in the foliar concentration of antioxidant compounds such as ascorbate and GSH. These data indicate that an application of selenate at low rates can be used to prevent the induction in plants of the antioxidant system, thereby improving stress resistance. [source]


    Selenium incorporation using recombinant techniques

    ACTA CRYSTALLOGRAPHICA SECTION D, Issue 4 2010
    Helen Walden
    Using selenomethionine to phase macromolecular structures is common practice in structure determination, along with the use of selenocysteine. Selenium is consequently the most commonly used heavy atom for MAD. In addition to the well established recombinant techniques for the incorporation of selenium in prokaryal expression systems, there have been recent advances in selenium labelling in eukaryal expression, which will be discussed. Tips and things to consider for the purification and crystallization of seleno-labelled proteins are also included. [source]