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Query: UMLS:C0242706 (hyperoxia)
 5,219 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of hyperoxia on the level of the antioxidants: glutathione (GSH) in the whole blood and the enzymes, catalase, superoxide dismutase (SOD), glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6-PGD), was studied in the erythrocytes of male high school students living at Dead Sea level (390 m below Sea level and 794.7 mm Hg), and compared with those of students living at Amman level (766 m above sea level and 697.5 mm Hg). The levels of the antioxidant enzymes were found to be lower at Dead Sea level than in Amman, except for the catalase level, which was similar in both groups. The ratio of GSH/Hb was significantly higher in the blood of students at Dead Sea level than in Amman. The combined activities of the antioxidants protected the RBC's but permitted increased level of GSH/Hb in the blood to protect peripheral cells from damage by oxidants.
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PMID:Comparative study of the levels of antioxidants of students at Amman and Dead Sea level. 829 93

Nitric oxide (NO) shows cytotoxicity, and its reaction products with reactive oxygen species, such as peroxynitrite, are potentially more toxic. To examine the role of O2 in the NO toxicity, we have examined the proliferation of cultured human umbilical vein endothelial cells in the presence or absence of NO donor, ((Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-++ +ium-1,2-diolate) (DETA-NONOate) (100-500 microM), under normoxia (air), hypoxia (< 0.04% O2) or hyperoxia (88-94% O2). It was found that the dose dependency on NONOate was little affected by the ambient O2 concentration, showing no apparent synergism between the two treatments. We have also examined the effects of exogenous NO under normoxia and hyperoxia on the cellular activities of antioxidant enzymes involved in the H2O2 elimination, since many of them are known to be inhibited by NO or peroxynitrite in vitro. Under normoxia DETA-NONOate (500 microM) caused 25% decrease in catalase activity and 30% increases in glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities in 24h. Under hyperoxia NO caused about 25% decreases in activities of catalase, glutathione reductase and glucose-6-phosphate dehydrogenase. The H2O2 removal rate by NO-treated cells was computed on the mathematical model for the enzyme system. It was concluded that the cellular antioxidant function is little affected by NO under normoxia but that it is partially impaired when the cells are exposed to NO under hyperoxia.
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PMID:Interactions of nitric oxide and oxygen in cytotoxicity: proliferation and antioxidant enzyme activities of endothelial cells in culture. 1088 22