Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:1.11.1.9 (glutathione peroxidase)
22,002 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The early interest in selenium related primarily to its toxicity, but since 1957 the element has been recognized as a dietary essential. The dietary requirement for selenium by most species is about .1 ppm. Deficiencies of selenium in cattle and sheep have been confirmed under natural grazing conditions in many countries of the world. Overt signs of inadequacy such as white muscle disease (nutritional muscular dystrophy) occur primarily in young calves or lambs born to selenium deficient dams. Infertility has increased in ewes grazing pastures low in selenium. In general, signs of deficiency have not occurred in older animals such as finishing beef cattle and lactating dairy cows. Subclinical deficiencies of selenium are not determined easily, however, and thus an inadequacy of the element may be limiting maximum animal performance under certain circumstances of drylot feeding. The current nutritional status of ruminant animals in many geographical areas and involving various feeding programs with this element has not been established. The recent widespread deficiency problems with nonruminants suggest that such an assessment should be made. Concentration of selenium in tissue, particularly in the liver, has been used in establishing selenium status of the animal. With lambs glutathione peroxidase activity in certain tissues may be a more accurate indicator of selenium adequacy than is selenium content of the tissue. Supplemental sodium selenite and sodium selenate by either oral administration or parenteral injection have prevented clinical signs of selenium deficiency and animal losses in both ruminant and nonruminant animals. Heavy pellets containing elemental selenium for placement in the rumen have proved effective. In general, organic forms of selenium are absorbed more readily by animals than are inorganic compounds. The dietary requirements for selenium and its metabolism are influenced by many nutrient interrelationships, including its interactions with sulfur, lipids, vitamin E, proteins, amino acids, and several microelements. The Food and Drug Administration gave approval in 1974 for the oral administration of supplemental selenium as either sodium selenite or sodium selenate to certain classes of swine and poultry. Similar approval in the United States for ruminants will require additional information, particularly with regard to the influence of dietary intake on concentrations of selenium in tissue and milk in beef and dairy animals.
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PMID:Selenium in ruminant nutrition: a review. 110 75

This study examined the effects of gossypol acetic acid on the antioxidant defense system of the rat testis. In gossypol-treated animals testis catalase and glutathione peroxidase activities were decreased. Catalase and glutathione peroxidase are the two enzymes that protect against oxidative damage by hydrogen peroxide. Other antioxidants that were reduced in treated animals were glucose-6-phosphate dehydrogenase, superoxide dismutase, glutathione reductase, alpha-tocopherol, and ascorbate. Gossypol, a pigment of cottonseed and cottonseed products, causes infertility in humans and many animal species, but its mechanism of action is unknown. Gossypol is known to produce reactive oxygen species in vitro. Oxidative injury caused by the generation of reactive oxygen species and a compromised antioxidant defense system may be responsible for the antifertility effects of gossypol.
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PMID:Effects of gossypol on the antioxidant defense system of the rat testis. 319 Mar 61

The purpose of this study was to evaluate the follicular fluid selenium status of in vitro fertilization patients in relation to their individual characteristics and treatment outcome. A total of 135 samples of follicular fluid were collected from 112 patients during transvaginal oocyte retrieval. Selenium levels and glutathione peroxidase (GSHPx) activity were measured in follicular fluid (FF) and blood serum. A selenium dependent GSHPx activity in follicular fluid has been demonstrated. Patients with unexplained infertility had significantly decreased follicular selenium levels as compared with those with tubal infertility or male factor. The mean GSHPx activity in follicles yielding oocytes which were subsequently fertilized exceeded that of the follicles with non-fertilized oocytes. Tobacco smoking resulted in significantly diminished follicular GSHPx activity. The Se/GSHPx pattern of the FF seems to be significant for the evaluation of the follicular milieu.
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PMID:Selenium dependent glutathione peroxidase activity in human follicular fluid. 755 84

Six women with a history of unexplained infertility or early miscarriage and who had failed to normalize their red cell magnesium (RBC-Mg) levels after four months of oral magnesium supplementation (600 mg/day) were investigated for red cell glutathione peroxidase activity (RBC-GSH-Px) and were compared with six age-matched women with a history of unexplained infertility or miscarriage who did normalize their RBC-Mg levels on magnesium supplementation. The six non-normalizers had significantly lower (P < 0.0001) RBC-GSH-Px levels than the six normalizers. After a further two months of 200 micrograms daily oral selenium as selenomethionine and oral magnesium supplements, all six women normalized their RBC-Mg (P < 0.0001) and RBC-GSH-Px (P < 0.0001) levels. All 12 previously infertile women have produced normal healthy babies all conceiving within eight months of normalizing their RBC-Mg levels. The possible relevance of these findings to the medical treatment of infertility is discussed.
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PMID:Red cell magnesium and glutathione peroxidase in infertile women--effects of oral supplementation with magnesium and selenium. 805 61

Reactive oxygen species (ROS) are cytotoxic, causing inflammatory disease, including tissue necrosis, organ failure, atherosclerosis, infertility, birth defects, premature aging, mutations and malignancy. ROS are produced in the metabolism of drugs and industrial chemicals by (i) one-electron peroxidase oxidations to form cation radicals, (ii) cytochrome P450 metabolism to free radical products, (iii) stabilisation of the ROS-generator, CYP2E1, and (iv) futile cycling of other cytochromes P450. ROS production initiates inflammation which unless quenched may result in chronic inflammatory disease states, e.g. hepatitis, nephritis, myositis, scleroderma, lupus erythematosus, multiple system organ failure. Quenching of ROS is affected by the redox buffer, glutathione (GSH), and the antioxidants, ascorbic acid, tocopherols, retinoids, in conjunction with the redox enzymes, GSH reductase, GSH peroxidase, catalase and superoxide dismutase. Many industrial workers with symptoms of systemic inflammation, resulting from exposure to toxic chemicals, are diagnosed as having rheumatoid arthritis, virus infections, or other microbial lesions, largely because many physicians are unaware that exposure to certain chemicals can initiate inflammatory disease states.
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PMID:Chemical toxicity and reactive oxygen species. 911 92

The chain-breaking antioxidant alpha-tocopherol has not been reported to be present in mammalian spermatozoa, unlike other cell types where it contributes to cell integrity and function. Semen samples obtained from 36 male partners of infertile couples during infertility investigations were analysed for alpha-tocopherol content of seminal plasma and spermatozoa, and the superoxide dismutase and glutathione peroxidase activities of spermatozoa were determined concomitantly with routine semen analysis. A wide range of alpha-tocopherol concentrations was detected in human spermatozoa (85 +/- 51 ng/10(8) spermatozoa, range 10-245). The concentration of alpha-tocopherol in spermatozoa was not found to be significantly related to the concentration or the total amount of alpha-tocopherol in seminal plasma. The percentage of motile spermatozoa was significantly related to sperm alpha-tocopherol content (r = 0.84, P < 0.001). alpha-tocopherol concentration and superoxide dismutase and glutathione peroxidase activities of spermatozoa were significantly elevated when the semen samples contained < 10(6) leukocytes/ml (mean +/- SD, 94 +/- 53 compared with 54 +/- 29 ng/10(8) spermatozoa, P < 0.02, 1.15 +/- 0.41 compared with 0.77 +/- 0.30 IU/10(8) spermatozoa, P < 0.02 and 60 +/- 26 compared with 30 +/- 14 spermatozoa mlU/10(8) spermatozoa, P < 0.005 respectively). From these results, it is suggested that alpha-tocopherol might play a role in association with antioxidant enzymes, for preserving the functional competence of spermatozoa subjected to an oxidative attack.
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PMID:alpha-Tocopherol in human spermatozoa and seminal plasma: relationships with motility, antioxidant enzymes and leukocytes. 923 91

In men from couples consulting for infertility, 72% of washed sperm preparations produced detectable amounts of reactive oxygen species (ROS) compared to only 25% of preparations from a population of fertile donors. High ROS production was associated with oligozoospermia and poor sperm function. The rate of ROS production was closely correlated with the concentration of leukocytes (r = 0.826) and the degrees of stimulation by N-formyl-methionyl-leucyl-phenyl alanine (NFMLP) and by phorbol 12-myristate 13 acetate (PMA) were similar (r = 0.923). The removal of leukocytes with 'Dynabeads' either abolished or substantially decreased ROS production but in a few cases ROS production that could be stimulated by PMA but not NFMLP was observed in leukocyte-free preparations. When sperm preparations which produced ROS were incubated under 95% O2 there was a rapid 40% decrease in the number of sperm that could be stimulated to acrosome react although the acrosome reaction was unaffected by incubation under 95% N2 for up to 6 h. The harmful effect of oxygen was not seen in preparations that produced no ROS and could be prevented by removing leukocytes from the suspension or by adding superoxide dismutase and catalase. We conclude that leukocytes are the predominant source of ROS in human sperm preparations and that the ROS they produce are harmful to sperm. On the other hand these data confirm that highly purified sperm can produce ROS albeit in smaller amounts. We have demonstrated that flux through the pentose phosphate pathway (PPP) in purified sperm preparations increases in response to oxidative stress. This is required to make reduced glutathione available for glutathione peroxidase and we suggest that measurement of PPP flux provides an index of the capacity of glutathione peroxidase to protect sperm against oxidation.
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PMID:Reactive oxygen species in human sperm suspensions: production by leukocytes and the generation of NADPH to protect sperm against their effects. 946 85

Several decades after the discovery of selenium as an essential trace element in vertebrates approximately 20 eukaryotic and more than 15 prokaryotic selenoproteins containing the 21st proteinogenic amino acid, selenocysteine, have been identified, partially characterized or cloned from several species. Many of these proteins are involved in redox reactions with selenocysteine acting as an essential component of the catalytic cycle. Enzyme activities have been assigned to the glutathione peroxidase family, to the thioredoxin reductases, which were recently identified as selenoproteins, to the iodothyronine deiodinases, which metabolize thyroid hormones, and to the selenophosphate synthetase 2, which is involved in selenoprotein biosynthesis. Prokaryotic selenoproteins catalyze redox reactions and formation of selenoethers in (stress-induced) metabolism and energy production of E. coli, of the clostridial cluster XI and of other prokaryotes. Apart from the specific and complex biosynthesis of selenocysteine, selenium also reversibly binds to proteins, is incorporated into selenomethionine in bacteria, yeast and higher plants, or posttranslationally modifies a catalytically essential cysteine residue of CO dehydrogenase. Expression of individual eukaryotic selenoproteins exhibits high tissue specificity, depends on selenium availability, in some cases is regulated by hormones, and if impaired contributes to several pathological conditions. Disturbance of selenoprotein expression or function is associated with deficiency syndromes (Keshan and Kashin-Beck disease), might contribute to tumorigenesis and atherosclerosis, is altered in several bacterial and viral infections, and leads to infertility in male rodents.
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PMID:Selenium in biology: facts and medical perspectives. 1107 17

The aim of the study was to assess the levels of antioxidative enzymes--superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in the whole semen of men treated for infertility. The first group consisted of the patients with normozoospermia; the second--included the men with oligozoospermia. According to sperm motility, the patients were divided into the third group--motility higher than 50% and the fourth group--motility lower than 50%. The study showed that the levels of both enzymes were higher in men with oligozoospermia than those with normozoospermia. It was also found that the activities of SOD and GSH-Px were higher in men with low motility(< 50%) compared to high motility patients. The results confirm that the activity of superoxide dismutase and glutathione peroxidase is related to the parameters of human semen assessed according to the WHO standards.
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PMID:Activity of superoxide dismutase and glutathione peroxidase in human semen in normozoospermia and spermatopathy. 1289 64

In recent years, the role of selenium in the prevention of a number of degenerative conditions including cancer, inflammatory diseases, thyroid function, cardiovascular disease, neurological diseases, aging, infertility, and infections, has been established by laboratory experiments, clinical trials, and epidemiological data. Most of the effects in these conditions are related to the function of selenium in antioxidant enzyme systems. Replenishing selenium in deficiency conditions appears to have immune-stimulating effects, particularly in patients undergoing chemotherapy. However, increasing the levels of selenoprotein antioxidant enzymes (glutathione peroxidase, thioredoxin reductase, etc.) appears to be only one of many ways in which selenium-based metabolites contribute to normal cellular growth and function. Animal data, epidemiological data, and intervention trials have shown a clear role for selenium compounds in both prevention of specific cancers and antitumorigenic effects in post-initiation phases of cancer.
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PMID:Selenium biochemistry and cancer: a review of the literature. 1538 17


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