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Query: UMLS:C0003129 (Anoxia)
 551 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The garter snake Thamnophis sirtalis parietalis can readily tolerate several hours of freezing or anoxia exposure. Both stresses halt oxygen availability to tissues and to endure these stresses snakes must cope with potential oxidative stress arising as a result of the ischemic/anoxic condition followed by reperfusion of aerated blood during recovery. To determine whether antioxidant defenses are important for freezing and anoxia survival, we monitored the activities of antioxidant enzymes and the levels of glutathione (GSH and GSSG) during freezing (5 h at -2.5 degrees C) and anoxia (10 h under N2 gas at 5 degrees C) exposures in three organs (muscle, liver, and lung) of snakes. Freezing resulted in a significant rise in the activity of muscle and lung catalase (by 183 and 63%) and in muscle glutathione peroxidase (52%). Anoxia enhanced muscle and liver superoxide dismutase activities (by 59 and 118%) and also caused a 57% increase in muscle GSH levels. The increase in muscle GSH concentration in anoxia (from 0.45 to 0.71 mM) could also stimulate muscle glutathione peroxidase activity in vivo by 1.5-fold because of its low affinity for GSH (Km = 11 mM). The ratio of GSSG/GSH was not affected by experimental state in any tissue, suggesting that oxidative stress did not occur during the freezing or anoxic exposure. Rather, H2O2- and O2(-)-detoxification systems may be activated in preparation for possible oxygen free radical overgeneration during thawing or reoxygenation. Antioxidant defenses appear to be part of the adaptive machinery for reptilian tolerance of freezing and anoxia.
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PMID:Antioxidant defenses in the tolerance of freezing and anoxia by garter snakes. 821 60

The effects of anoxia and reoxygenation on major antioxidant enzyme activities were investigated in vitro in immortalized rat brain endothelial cells (RBE4 cells). A sublethal anoxic period of 12 h was assessed for RBE4 cells using the neutral red uptake test. Anoxia markedly influenced the specific activity of catalase and superoxide dismutase, with no major effect on glutathione peroxidase or glutathione reductase. After 24 h postanoxia, the superoxide dismutase activity modulated by the presence or absence of oxygen returned to control value. Damage and recovery of RBE4 immortalized rat brain endothelial cells in culture after exposure to free radicals and other oxygen-derived species provides a useful in vitro model to study anoxia-reoxygenation trauma at the cellular level.
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PMID:Effect of anoxia and reoxygenation on antioxidant enzyme activities in immortalized brain endothelial cells. 872 46

The effects of anoxic submergence (20 h at 5 degrees C) and subsequent 24 h aerobic recovery on the antioxidant systems of six organs were examined in freshwater turtles, Trachemys scripta elegans. Both xanthine oxidase and xanthine dehydrogenase were detected in turtle tissues with xanthine oxidase composing 36-75% of the total activity. Turtle organs displayed high constitutive activities of catalase (CAT), superoxide dismutase (SOD), and alkyl hydroperoxide reductase (AHR). Measurements of lipid peroxidation damage products (conjugated dienes, lipid hydroperoxides, thiobarbituric acid reactive substances) showed minimal changes during anoxia or recovery suggesting that natural anoxic-aerobic transitions occur without the free radical damage that is seen during ischemia-reperfusion in mammals. Anoxia exposure led to selected decreases in enzyme activities in organs, consistent with a reduced potential for oxidative damage during anoxia: SOD decreased in liver by 30%, CAT decreased in heart by 31%, CAT and total glutathione peroxidase (GPOX) decreased in kidney (by 68 and 41%), and CAT and SOD decreased in brain (by 80 and 15%). AHR, however, increased 2 and 3.5 fold during anoxia in heart and kidney respectively. Most anoxia-induced changes were reversed during aerobic recovery although brain enzyme activities remained suppressed. Some specific changes occurred during the recovery period: SOD increased from controls in heart by 45%, AHR increased to 200 and 168% of control values in red and white muscle respectively, and total GPOX decreased from controls in heart and white muscle by 75 and 77% respectively. The results show that biochemical adaptation for natural anoxia tolerance in turtles includes well-developed antioxidant defenses that minimize or prevent damage by reactive oxygen species during the reoxygenation of organs after anoxic submergence.
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PMID:Antioxidant systems and anoxia tolerance in a freshwater turtle Trachemys scripta elegans. 914 33

The purpose of this work was to evaluate the response of the antioxidant system of goldfish Carassius auratus during anoxia and reoxygenation. The exposure of goldfish to 8 h of anoxia induced a 14% decrease in total glutathione levels in the kidney, although the liver, brain, and muscle were unaffected. Anoxia also resulted in increases in the activities of liver catalase, brain glucose-6-phosphate dehydrogenase, and brain glutathione peroxidase (by 38, 26, and 79%, respectively) and a decrease in kidney catalase activity (by 17.5%). After 14 h of reoxygenation, liver catalase and brain glutathione peroxidase activities remained higher than controls and several other tissue-specific changes occurred in enzyme activities. Superoxide dismutase activity was unaffected by anoxia and reoxygenation. The levels of conjugated dienes, as indicators of lipid peroxidation, increased by 114% in liver after 1 h of reoxygenation and by 75% in brain after 14 h of reoxygenation. Lipid peroxidation was unaffected in kidney and depressed during anoxia and reoxygenation (by 44-61%) in muscle. Regulation of the goldfish antioxidant system during anoxia may constitute a biochemical mechanism that minimizes oxidative stress following reoxygenation.
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PMID:Oxidative stress and antioxidant defenses in goldfish Carassius auratus during anoxia and reoxygenation. 1112 39

Most organisms are repeatedly exposed to oxidative stress from multiple sources throughout their lifetimes, potentially affecting all aspects of organismal performance. Here we test whether exposure to a conditioning bout of anoxia early in adulthood induces a hormetic response that confers resistance to oxidative stress and enhances male sexual performance later in life in the Caribbean fruit fly, Anastrepha suspensa. Anoxic conditioning of adults prior to emergence led to an increase in antioxidant capacity driven by mitochondrial superoxide dismutase and glutathione peroxidase. When exposed to gamma irradiation, a strong oxidative stressor, males that received anoxic conditioning had lower lipid and protein oxidative damage at sexual maturity. Anoxia conditioning led to greater male sexual competitiveness compared with unconditioned males when both were irradiated, although there was no effect of anoxia conditioning on mating competitiveness in unirradiated males. Anoxia also led to higher adult emergence rates and greater flight ability in irradiation-stressed flies while preserving sterility. Thus, hormetic treatments that increased antioxidant enzyme activity also improved male performance after irradiation, suggesting that antioxidant enzymes play an important role in mediating the relationship between oxidative stress and sexual selection. Furthermore, our work has important applied implications for the sterile insect technique (SIT), an environmentally friendly method of insect pest control where males are sterilized by irradiation and deployed in the field to disrupt pest populations via mating. We suggest that hormetic treatments specifically designed to enhance antioxidant activity may produce more sexually competitive sterile males, thus improving the efficacy and economy of SIT programs.
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PMID:Short-term anoxic conditioning hormesis boosts antioxidant defenses, lowers oxidative damage following irradiation and enhances male sexual performance in the Caribbean fruit fly, Anastrepha suspensa. 2262 4