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PubMed1977

Enhanced lung toxicity of O2 in selenium-deficient rats.

To test the hypothesis that glutathione (GSH) peroxidase is an important component of the lung's anti-oxidant defense systemes, O2 toxicity was studied in selenium (Se)-deficient rats. Chronic respiratory disease free rats fed a Se-deficient diet or a diet supplemented with Se for 40 days after weaning were exposed to 80% O2 at atmospheric pressures for 3 days. Activities of GSH peroxidase in lungs of Se-deficient rats were markedly lower than corresponding activities in rats supplemented with 0.5 or 2.0 ppm Se. With O2 exposure, 35% of the rats fed the Se-deficient regimen died, whereas all rats fed Se-supplemented diets survived. Lungs from surviving Se-deficient rats exposed to O2 were edematous. The data suggest that the toxic effects of O2 are enhanced in Se-deficient rats and that nutritional factors contribute to lung susceptibility to oxidant-induced damage.

Animals↗
PubMed2005

Nutritional, dietary and postprandial oxidative stress.

Nutritional, or dietary oxidative stress denotes a disturbance of the redox state resulting from excess oxidative load or from inadequate nutrient supply favoring prooxidant reactions. Low intake or impaired availability of dietary antioxidants including vitamins E and C, carotenoids, polyphenols, and other micronutrients (e.g., selenium) weakens the antioxidant network. Postprandial oxidative stress, as a subform of nutritional oxidative stress, ensues from sustained postprandial hyperlipidemia and/or hyperglycemia and is associated with a higher risk for atherosclerosis, diabetes, and obesity. In Western societies, a significant part of the day is spent in the postprandial state. Unsaturated fatty acids incorporated into LDL and oxidized LDL are an atherogenic factor. Lipid hydroperoxides present in the diet are absorbed, contributing to the prooxidant load. In hyperlipidemic and hyperglycemic subjects, endothelium-dependent vasodilation is impaired in the postprandial state, making postprandial oxidative stress an important factor modulating cardiovascular risk. Postprandial oxidative stress is attenuated when dietary antioxidants are supplied together with a meal rich in oxidized or oxidizable lipids. Ingestion of dietary polyphenols, e.g., from wine, cocoa, or tea, improves endothelial dysfunction and lowers the susceptibility of LDL lipids to oxidation. Polyphenols affect endothelial function not solely as antioxidants but also as modulatory signaling molecules.

Antioxidants↗
PubMed2001

Catalytic selenols couple the redox cycles of metallothionein and glutathione.

Co-ordination of zinc to the thiol group of cysteine allows mobilization of zinc through oxidation of its ligand. This molecular property links the binding and release of zinc in metallothionein (MT) to the cellular redox state [Maret W. & Vallee B.L. (1998) Proc. Natl Acad. Sci. USA 95, 3483-3488]. Biological disulfides such as glutathione disulfide (GSSG) oxidize MT with concomitant release of zinc, while glutathione (GSH) reduces the oxidized protein to thionein, which then binds to available zinc. Neither of these two redox processes is very efficient, even at high concentrations of GSSG or GSH. However, the GSH/GSSG redox pair can efficiently couple with the MT/thionein system in the presence of a selenium compound that has the capacity to form a catalytic selenol(ate). This coupling provides a very effective means of modulating oxidation and reduction. Remarkably, selenium compounds catalyze the oxidation of MT even under overall reducing conditions such as those prevailing in the cytosol. In this manner, the binding and release of zinc from zinc-thiolate co-ordination sites is linked to redox catalysis by selenium compounds, changes in the glutathione redox state, and the availability of either a zinc donor or a zinc acceptor. The results also suggest that the pharmacological actions of selenium compounds in cancer prevention and other antiviral and anti-inflammatory therapeutic applications, as well as unknown functions of selenium-containing proteins, may relate to coupling between the thiol redox state and the zinc state.

Catalysis↗
PubMed1991

Combination of dietary factors in relation to breast-cancer occurrence.

Combinations of dietary factors were studied in relation to breast-cancer occurrence among 133 breast cancer cases and 289 population controls in The Netherlands. Dietary factors were classified according to their possible mechanism of action, i.e., relating either to the intestinal microflora (total fat, fiber, fermented milk products) or to the anti-oxidant hypothesis (beta-carotene, selenium and polyunsaturated fatty acids). From 6 interactions evaluated, the combination of high fiber intake and high intake of fermented milk products was the only one suggesting synergistic protection (age-and-fat-adjusted OR for interaction = 0.48, 95% confidence interval (CI) = 0.21 - 1.13). In order to estimate the extent to which the above dietary factors together might be related to breast cancer, subjects with a supposedly favorable dietary pattern (low fat intake, high fiber intake, high intake of fermented milk products; high intake of beta-carotene and selenium, low intake of polyunsaturated fatty acids) were compared with subjects with an unfavorable dietary pattern. This resulted in an age-adjusted odds ratio of 0.40 (95% CI = 0.14 - 1.15), which was largely attributable to the combination of low intake of fat and high intake of fermented milk products and fiber (age-adjusted OR = 0.33, 95% CI = 0.15 - 0.73). The other factors did not appreciably affect the odds ratio. These analyses show in a quantitative way that a dietary pattern which combines low intake of fat and high intake of fiber and fermented milk products might provide substantial protection against breast cancer.

Adult↗
PubMed2004

A longitudinal study of antioxidant status in phenylketonuric patients.

OBJECTIVES: To investigate the implications of the three main factors of the antioxidant system reported in relation to oxidative damage in phenylketonuric patients: selenium, ubiquinone-10 (Q10) and antioxidant enzymes over 3 years of metabolic follow-up. DESIGN AND METHODS: Longitudinal study of 46 phenylketonuric patients (age range: 6 months-34 years). Antioxidants were measured by atomic absorption spectrophotometric, chromatographic and spectrophotometric procedures. RESULTS: Plasma selenium concentrations in phenylketonuria (PKU) were not different from those of a healthy population. Decreased plasma Q10 concentrations were mainly related to the dietary control and the age of patients. Erythrocyte catalase activity was significantly decreased in PKU while the other enzyme activities were not different from those of a healthy population. CONCLUSION: Selenium status is not impaired in phenylketonuric patients under dietary treatment. Q10 values tend to decrease with increased patient age. Catalase activity was negatively associated with plasma phenylalanine values.

Adolescent↗
PubMed1994

Diet-induced lipofuscin and ceroid formation in growing pigs.

Seven piglets, aged 2 weeks at the beginning of the experiment, were fed a diet lacking antioxidants (vitamin E and selenium) and enriched with thermally oxidated cod liver oil (the peroxide value of which was 310 meqv/kg). From one month before to 4 weeks after farrowing (weaning) the sow also received the experimental diet. One pig died at 9 days of age, due to degeneration of the parenchymal tissues. The oxidative stress produced was aggravated in four of the seven remaining pigs by giving them an injection of iron-dextran (300 mg) one day before the animals were killed for necropsy at the age of 2 months. The three other piglets were given an injection of a control saline solution. The nutritional myodegeneration produced ('white muscle disease') was characterized by a pale, yellowish colour and translucence of skeletal muscle, with degeneration, including swelling of the muscle fibres and slackening of the fibrillar pattern. The arrangement of nuclei in chains indicated repair. Ultrastructurally, skeletal muscle showed vacuolization of the sarcoplasmic reticulum, irregularities in the mitochondria and focal dissolution of myofibrils. The sarcoplasmic reticulum displayed condensation and lamellar formations. Hyaline degeneration of the heart muscle occurred both in iron-treated and control pigs, and in six animals a yellowish pigment resembling lipofuscin and ceroid was observed. Ultrastructurally, the ceroid deposits appeared as myelin-like figures. The livers were pale and brittle, four with centrilobular degeneration. By light microscopy, lipidosis was distinguished in four and ceroid accumulations in three pigs. Thiobarbituric-acid-reactive substances, creatine kinase activity and iron increased significantly in the serum as a result of the injection of iron-dextran.

Animal Feed↗
PubMed2002

Total synthesis of the anticancer natural product OSW-1.

The highly potent anticancer natural saponin OSW-1 has been successfully synthesized from commercially available 5-androsten-3beta-ol-17-one 79 in 10 operations with 28% overall yield. The key steps in the total synthesis included a highly regio- and stereoselective selenium dioxide-mediated allylic oxidation of 80 and a highly stereoselective 1,4-addition of alpha-alkoxy vinyl cuprates 68 to steroid 17(20)-en-16-one 12E to introduce the steroid side chain. This total synthesis demonstrated once again the versatile synthetic applications of alpha-halo vinyl ether chemistry developed in our laboratories.

Antineoplastic Agents, Phytogenic↗
PubMed2005

Amorphous Se: a new platform for synthesizing superparamagnetic colloids with controllable surfaces.

We have successfully incorporated iron oxide nanoparticles into monodispersed amorphous selenium (a-Se) colloids by regulating the reaction temperature during the synthesis of a-Se. The surfaces of these a-Se colloids could be coated with conformal and smooth shells made of Pt and SiO2. The Se cores could then be removed by etching with hydrazine. The spherical morphology and superparamagnetism were maintained in all these synthetic steps. The presence of Pt and SiO2 on the outer surfaces of these colloidal particles allows one to control their surface functionalities through the formation of alkanethiolate and siloxane monolayers, respectively.

Colloids↗
PubMed2004

Synthesis and structures of beta-diketiminatotin(II) halides, an amide and of Sn(=E)[{N(R)C(Ph)}2CH](NR2) (E = S or Se, R = SiMe3).

Treatment of [Li(L1)]2 (1) or K(L2) (2) with SnX2 in Et2O yielded the heteroleptic beta-diketiminatotin(II) halides Sn(L1)Cl (3a), Sn(L1)Br (3b) or Sn(L2)Cl (4), even when an excess of the alkali metal beta-diketiminate was used [L1={N(R)C(Ph)}2CH, L2={N(R)C(Ph)CHC(But)N(R)}, R = SiMe3]. From and half an equivalent each of SnCl2.2H2O and SnCl2, or one equivalent of SnCl2.2H2O, the product was Sn(L3)Cl (5) or Sn(L4)Cl (6), in which one or both of the N-R bonds of L1 had been hydrolytically cleaved; the compound Sn(L5)Cl (7) was similarly obtained from and an equivalent portion of SnCl2.2H2O [L3={N(R)C(Ph)CHC(But)N(H)}, L4={N(H)C(Ph)CHC(But)N(H)} and L5={N(H)C(Ph)}2CH]. The halide exchange between 3a and 3b, studied by two-dimensional (119)Sn{1H}-NMR spectroscopy, is attributed to implicate a (mu-Cl)(mu-Br)-dimeric intermediate or transition state. The 13C{1H}-NMR spectra of or showed two distinct resonances for each group, which coalesced on heating, corresponding to DeltaG(338 K)= 69.4 (3a) or 72.8 (3b) kJ mol(-1). The chloride ligand of was readily displaced by treatment with NaNR2, CF3SO3H or CH2(COPh)2, yielding Sn(L1)X [X = NR2 (8), O3SCF3 (9) or {OC(Ph)}2CH (10)]. Oxidative addition of sulfur or selenium to gave the tin(IV) terminal chalcogenides Sn(E)(L1)(NR2)[E = S (11) or Se (12)]. The X-ray structures of the cocrystal of 3a/3b and of the crystalline compounds 5, 6, 8, 11 and are presented, as well as multinuclear NMR spectra of each of the new compounds.

Journal Article↗
PubMed2004

Fruits and the prevention of lifestyle-related diseases.

1. Fruits contain a variety of compounds that may slow or prevent chronic diseases through a variety of possible mechanisms. Components in fruits thought to be associated with the reduction of these conditions include soluble and insoluble dietary fibre, anti-oxidant nutrients (vitamins C, E, selenium, beta-carotene) and phytonutrients (bioactive plant compounds that impart colour, flavour and other functional properties to foods). 2. The present paper briefly reviews selected studies on the role of some fruits in lifestyle conditions such as cardiovascular disease, some types of cancer and conditions that accompany ageing.

Animals↗
PubMed1991

Interactions of serum copper, selenium, and low density lipoprotein cholesterol in atherogenesis.

OBJECTIVE: To investigate the interactions between serum copper, selenium, and low density lipoprotein cholesterol concentrations with regard to the progression of carotid atherosclerosis. DESIGN: Longitudinal study of a cohort of middle aged men followed up for 24 months. SETTING: Epidemiological survey of the population of seven communities in eastern Finland. SUBJECTS: 126 men aged 42, 48, 54, or 60 at examination randomly selected from a population based sample of 2682 men. MAIN OUTCOME MEASURES: Increase in maximal carotid intima media thickness. RESULTS: The mean increase in the maximal common carotid intima media thickness after two years was greater in men with high serum copper concentrations (0.16 mm compared with 0.08 mm in men with concentrations less than 17.6 mumol/l; p = 0.010), those with low serum selenium concentrations (0.15 mm compared with 0.09 mm in men with concentrations greater than or equal to 1.40 mumol/l; p = 0.035), and those with raised serum low density lipoprotein cholesterol concentrations (0.15 mm compared with 0.08 mm in men with concentrations less than 4.0 mmol/l; p = 0.032) after adjustment for age and cigarette pack years in a three way analysis of covariance. A raised serum low density lipoprotein concentration was associated with accelerated progression of atherosclerosis only in men with higher than median serum copper concentrations (net difference 0.22 mm; p less than 0.001 for two way interaction), and this synergism was even more pronounced in men with serum selenium concentrations below the median value (net difference 0.41 mm; p = 0.042 for three way interaction). CONCLUSION: These data provide evidence of a synergistic effect of copper (a pro-oxidant), a low serum concentration of selenium (a cofactor of an enzyme that scavenges free radicals), and low density lipoprotein cholesterol concentration in atherogenesis.

Adult↗
PubMed2002

[The point about...uremia and cancer].

There have been long-lasting controversies as to whether uremic patients are prone to develop cancer. Recent epidemiological data support a small, but significant increase of various solid tumors, particularly those known to be induced by viruses. Paradoxically, either younger or female patients are the most exposed to the risk of cancer. In addition to factors linked to the underlying renal disease (e.g. analgesic abuse, "chinese herbs" or immunosuppressive drugs), uremia per se can enhance carcinogenesis through many different pathways: retention of various carcinogens; abnormalities of nucleic acids; decreased immune response; metabolic and nutritional changes (hyperhomocysteinemia, iron or selenium depletion...); deleterious effects of oxidative stress secondary to bioincompatibility reactions during dialysis. However, except for the ultrasonographic diagnosis of cystderived renal carcinoma, which has been shown beneficial in the younger patients, there should be no routine cancer screening peculiar to uremic patients.

Humans↗
PubMed1981

p-Azidophenylglyoxal. A heterobifunctional photoactivable cross-linking reagent selective for arginyl residues.

1. The synthesis described is of p-azidophenylglyoxal (p-APG) by diazotization of p-aminoacetophenone to an intermediate which when reacted with sodium azide gives p-azidoacetophenone; oxidation of the latter with selenium dioxide gives rise to p-APG (corrected melting point, 103-105 degrees C). The phenylglyoxal moiety was designed to react with arginine residues, whereas the p-azidoaryl function generates a reactive nitrene when activated with UV light; p-APG reacts most selectively with arginine and to a lesser extent with cystine and histidine. 2. p-APG has absorption peaks at 205 and 280 nm which decrease on photolysis. 3. Bovine heart lactic dehydrogenase, egg white lysozyme, horse liver alcohol dehydrogenase, and yeast alcohol dehydrogenase, all enzymes having arginyl residues at their active sites, are inhibited by p-APG in the dark. 4. Gel electrophoresis of oligomeric enzymes having arginyl residues at their active sites and exposed to p-APG and to UV irradiation gave varying proportions of monomers and photocross-linked dimers, trimers, tetramers, and larger molecular weight aggregates.

Alcohol Oxidoreductases↗
PubMed1998

Parenteral selenium supplementation in critically ill patients--effects on antioxidant metabolism.

Decreased plasma selenium (Se) levels are common in critically ill patients. Oxidative stress is regarded as one possible cause of the Se deficiency. We investigated in 20 critically ill patients with decreased plasma selenium concentrations the antioxidant metabolism during parenteral selenium supplementation (week 1: 2 x 500 micrograms; week 2:1 x 500 micrograms, week 3:3 x 100 micrograms sodium selenite). As marker of oxidative stress we measured the plasma malondialdehyde levels on days 0, 1, 3, 7, 14, and 21. The content of reduced and oxidized glutathione as well as the leucocyte activity marker elastase were estimated on the same days. Initial plasma Se levels were considerably decreased (0.44 +/- 0.1 mumol/l, mean +/- SEM). After one day of supplementation Se concentrations were in the reference range. Plasma malondialdehyde levels and the ratio of oxidized and reduced glutathione were initially elevated and decreased beginning on day 3 of supplementation. The mean elastase level was 113 +/- 10 micrograms/l on day 0. On day 3 elastase values decreased significantly (85 +/- 13 micrograms/l, p < 0.05; day 21, 19 +/- 7 micrograms/l, p < 0.001). Antioxidant metabolism showed significant changes beginning after 72 hours of therapy. This latency may be explained with the induction of the enzyme glutathione peroxidase. The lowered plasma Se concentrations measured in the critically ill patients and the significant effects on antioxidant metabolism during supplementation emphasized the importance of selenium administration in these patients.

Adult↗
PubMed2004

N-acetyl cysteine, L-cysteine, and beta-mercaptoethanol augment selenium-glutathione peroxidase activity in glucose-6-phosphate dehydrogenase-deficient human erythrocytes.

In glucose-6-phosphate dehydrogenase (G6PD)-deficient erythrocytes, failure to maintain normal levels of reduced glutathione (GSH) due to decreased NADPH regeneration in the hexose monophosphate pathway results in acute hemolytic anemia following exposure to oxidative insults, such as ingestion of Vicia fava beans or use of certain drugs. GSH is a source of protection against oxidative attack, used by the selenium-dependent glutathione peroxidase (Se-GSH-Px)/reductase (GR) system to detoxify hydrogen peroxide and organic peroxides, provided that sufficient GSH is made available. In this study, Se-GSH-Px activity was analyzed in G6PD-deficient patients in the presence of reducing agents such as N-Acetyl cysteine, L-cysteine, and beta-mercaptoethanol. Se-GSH-Px activity was decreased in G6PD-deficient red blood cells (RBCs). N-Acetyl cysteine, L-cysteine, and beta-mercaptoethanol increased Se-GSH-Px activity in G6PD-deficient human erythrocytes, indicating that other reducing agents can be utilized to complement Se-GSH-Px activity in G6PD deficiency. Based on the increased susceptibility of G6PD-deficient patients to oxidative stress, the reported increase in Se-GSH-Px activity can facilitate the detoxification of reactive oxygen species.

Acetylcysteine↗
PubMed1983

Selenium and vitamin E deficiencies do not enhance lung inflammation from cigarette smoke in the hamster.

The early lung inflammatory response to cigarette smoke may be oxidant-mediated. We fed Syrian hamsters a diet deficient in selenium and vitamin E to determine whether impairment of the lung's antioxidant defenses might worsen inflammation induced by cigarette smoke. After 8 wk, cigarette-smoke-exposed animals had characteristic inflammatory lesions in the distal airways. Increased numbers of phagocytes, predominantly macrophages, were recovered by lavage and these cells exhibited enhanced oxidative metabolism. Animals fed the deficient diet had profound depletions of selenium and vitamin E, but no alterations in the histologic appearance of smoke-induced inflammatory lesions, in the numbers of phagocytes recruited, or in the oxidative metabolism of these phagocytes. These results suggest that selenium and vitamin E are unimportant in protecting against cigarette-smoke-induced lung injury.

Animals↗