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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous studies have demonstrated that reactive oxygen species are involved in ischemic injury. The present work was undertaken to determine in vivo the role of xanthine oxidase in the oxygen free radical production during rat liver ischemia and to examine the activity of antioxidant enzymes (superoxide dismutase, catalase and glutathione peroxidase) during the same period. Our results indicate a 4-fold increase in xanthine oxidase activity between 2 and 3 hours of normothermic ischemia, in parallel with a decrease in cell viability. Moderate hypothermia delays both events. Under the same conditions, the activity of oxygen radical scavenging enzymes remains unchanged. Moreover, we have compared in vitro the susceptibility of isolated liver cells to an oxidative stress induced by O2.-, H2O2 and .OH. Our results reveal that endothelial cells are much more susceptible to reactive oxygen species than hepatocytes, probably because they lack H2O2-detoxifying enzymes. These findings suggest that xanthine oxidase might play a major role in the ischemic injury mainly at the level of the sinusoidal space where most endothelial cells are located.
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PMID:Deleterious effects of xanthine oxidase on rat liver endothelial cells after ischemia/reperfusion. 748 47

The metabolic effects of combined antegrade/retrograde and antegrade cardioplegia on myocardial protection were evaluated and compared in 30 patients who underwent myocardial revascularization. All patients had three-vessel coronary artery disease, and the revascularization was done with exclusive use of arterial grafts (internal mammary artery, gastroepiploic artery). Myocardial protection consisted of oxygenated crystalloid cardioplegia, topical slushed ice, and moderate systemic hypothermia (34 degrees C). The patients were randomly separated into two groups: group A (n = 15), who received antegrade cardioplegia, and group A/R (n = 15), who received combined antegrade/retrograde cardioplegia. There was no significant difference between the two groups concerning preoperative and intraoperative data. After the first dose of cardioplegia, right ventricular temperature was significantly lower in group A/R (15 +/- 2 degrees versus 19 +/- 5 degrees C; p < 0.05), and there was no significant difference between the two groups in left ventricular temperature. Coronary sinus blood samples were obtained before bypass and 5, 10, and 15 minutes after reperfusion; there was no difference between the two groups concerning lactates, superoxide dismutase, and glutathione peroxidase. After reperfusion, malondialdehyde levels increased significantly in group A and there was no change in group A/R, with a significant difference between the two groups (at 10 minutes after reperfusion, 0.80 +/- 0.20 versus 0.53 +/- 0.16 mumol/L; p < 0.05). Right and left ventricular myocardial biopsies were performed before bypass and 15 minutes after reperfusion; there was no significant difference between the two groups concerning adenosine triphosphate and creatine phosphate myocardial concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Antegrade/retrograde cardioplegia in arterial bypass grafting: metabolic randomized clinical trial. 784 66

The level of glutathione and the activity of its exchange enzymes (glutathione reductase, glutathione-S-transferase, glutathione peroxidase), the content of malonic dialdehyde were studied in the red blood levels of 70 patients operated on under hypothermal perfusion for correction of acquired cardiac diseases. The plasma concentrations of myoglobin were also measured. There was a relationship of the time course of changes in the parameters in question to the depth of the body's cooling during surgical interventions. Shallow hypothermia (30-34 degrees C) caused a compensatory increase in the activity of glutathione peroxidase (by more than 30%) and in the concentration of glutathione (by more than 60%) at the cooling stage. Moderate hypothermia (26-29 degrees C) produced no impact on the level of glutathione and the activity of its exchange enzymes while deeper hypothermia (25 degrees C or below) induced decreases in the levels of glutathione (by more than 30 degrees C) and suppressed the activity of all the tested enzymes of its exchange. At the same time there are elevated concentrations of malonic dialdehyde at the warming-up stage and during early postperfusion. Myoglobin washing into plasma occurs under all temperature conditions of perfusion at the warming-up stages and in the early postperfusion period, but it is most profound in deeper hypothermia, which is caused by the toxic effect of oxygen whose plasma solubility increases with lowered temperatures.
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PMID:[Effect of various perfusion temperature regimens in heart surgery with extracorporeal circulation on glutathione levels and activity of enzymes of glutathione metabolism in erythrocytes]. 915 86

Oxidative stress is one of the major causes of cellular injury. Various reactive oxygen (ROS) and nitrogen (RNS) species such as superoxide, hydroxyl radical, peroxynitrite, and nitric oxide are involved in the manifestations of different types of organ toxicity and the resultant syndromes, symptoms, or diseases. Hypothermic conditions have been reported to reduce the oxidative stress in various in vitro and in vivo studies. In the present study, we sought to determine the effect of lowered temperatures on oxidative stress-induced cell death in Chinese hamster ovary (CHO) cells. We also investigated the oxidative stress-induced alterations in the expression of anti-apoptotic protein, bcl-2, in CHO cells at lowered temperatures. CHO cells were incubated at four different temperatures of 30, 32, 35, and 37 degrees C (control temperature) from 1 to 4 d. In another set, the cells were incubated with 100 microM hydrogen peroxide (H(2)O(2)) for 30 min before harvesting at different time points. The cells were harvested at 1, 2, 3, and 4 d. Cell survival was significantly higher at 30 degrees C as compared to 37 degrees C over 4 d of incubation. In cells incubated with H(2)O(2), significantly higher cell viability was observed at lower temperatures as compared to the cells incubated at 37 degrees C. The activity of glutathione peroxidase (GSH-Px) also increased significantly at lower temperatures. Lowered temperature also provided a significant increase in the expression of anti-apoptotic protein, bcl-2 after 4 d of incubation. These data suggest that hypothermic conditions lowers the risk of oxidative stress-induced cellular damage and programmed cell death by increasing the activity of GSH-Px and by the induction in the expression of the anti-apoptotic protein, bcl-2.
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PMID:Hypothermia enhances bcl-2 expression and protects against oxidative stress-induced cell death in Chinese hamster ovary cells. 1146 79

This experiment was carried out to determine the effect of short-term hypothermia on blood malondialdehyde (MDA), glutathione (GSH), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and glucose-6-phosphate dehydrogenase (G-6-PD) concentrations in rats. Twenty Sprague-Dawley rats were used weighing 180-200 g and on average 3.5 months old. They were randomly divided into two experimental groups: control (without cooling) and hypothermic (with cooling). The rats of the hypothermic group were cooled by immersion into cold water (10-12 degrees C), and the control rats were immersed into water of body temperature (37 degrees C) up to the neck without using any anaesthetic or tranquilizer for 3 min Rectal body temperatures of both groups were measured and blood samples to analyse MDA, GSH, SOD, GSH, GSH-Px and G-6-PD were collected immediately after the treatment. It was found that the MDA level was higher and the GSH and G-6-PD levels were lower in the hypothermic group than those in the controls. There was no difference between the control or hypothermic group regarding SOD or GSH-Px levels. It is concluded that acute hypothermia increased the lipid peroxidation and decreased the GSH and G-6-PD levels in rats.
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PMID:Effect of short-term hypothermia on lipid peroxidation and antioxidant enzyme activity in rats. 1222 69

The pathological sequelae of traumatic brain injury (TBI) include increased oxidative stress due to the production of reactive oxygen species (ROS). Regulation of ROS levels following TBI is determined primarily by antioxidant enzyme activity that in turn can be influenced by nerve growth factor (NGF). Hypothermia is one of the current therapies designed to combat the deleterious effects of TBI. However, it has been shown to suppress post-trauma increases in NGF levels in rat brain. The present study sought to determine whether post-injury hypothermia also impairs the antioxidant response to injury, and if such an effect could be reversed by infusion of exogenous NGF. We employed a lateral controlled cortical impact injury model in rat, followed by moderate hypothermia treatment with supplemental intracerebroventricular infusion of NGF or vehicle. The time course of changes in post-injury/intervention levels of NGF and activity of three major enzymes responsible for ROS scavenging, catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase (SOD), was determined in the hippocampus. Relative to levels in injured, normothermic animals, hypothermia treatment not only suppressed NGF levels, but also attenuated CAT and GPx activity, and increased SOD activity. Infusion of NGF in injured, hypothermia-treated animals was ineffective in restoring hippocampal antioxidant enzymes activity to levels produced after injury under normothermic conditions, although it was able to increase septal cholinergic (choline acetyltransferase) enzyme activity. These results have implications for clinical treatment of TBI, demonstrating that moderate hypothermia suppresses NGF and the antioxidant response after TBI; the latter cannot be countered by exogenous NGF administration.
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PMID:Effects of post-injury hypothermia and nerve growth factor infusion on antioxidant enzyme activity in the rat: implications for clinical therapies. 1528 6

After an ischemic insult, a multi-faceted complex cascade of biochemical reactions occurs that ultimately causes neurons death. Above reactions exert an influence on: immunological changes (activation of the complement system and the generation of antibodies), increased inflammation (actions of proinflammatory cytokines and chemokines), the production of reactive oxygen species leading to oxidative stress, diminished mitochondrial function and activation of apoptotic pathways. There is also intensive release and wrong reversible escapement many of neurotransmitters. The last one throught oxidative desamination are one of the main sources most of free radicals. Central nervous system is particularly susceptible to ROS-induced damage due to the high oxygen demands of the brain and low concentration of endogenous antioxidants. lts refer both enzymatic antioxidants: catalase, glutathione peroxidase, glutathione reductase, superoxide dismutase and nonenzymatic antioxidants glutathione, vitamin a, c, e, coenzym Q, uric acid etc. Presently there are no neuroprotective treatments and prevention. One way of treatment testing in clinical trials is hypothermia inhibits above-mentioned processes.
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PMID:[Contribution and role of important biochemic factors in cerebral ischemia]. 1678 Feb 50

Effects of oral vitamin E supplementation on blood malondialdehyde (MDA), glutathione (GSH) and vitamin E levels and superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) enzyme activities in acute hypothermia of guinea-pigs were investigated. Thirty male guinea pigs, weighing 500-800 g were randomly divided into one of three experimental groups: A (control, without cooling), B (hypothermic) and C (hypothermic with vitamin E supplementation). The guinea-pigs of group C received daily oral supplementation of 460 mg kg(-1) bw vitamin E for 4 days before inducing hypothermia. Twenty-four hours after the last vitamin E supplementation, the guinea-pigs of the B and C groups were cooled by immersion into cold water (10-12 degrees C), and the control guinea-pigs were immersed into water of body temperature (37 degrees C) up to the neck for 5 min without using any anaesthetic or tranquilizer. Rectal body temperatures of groups were measured and blood samples for biochemical analysis were collected immediately after the cooling. The body temperature, GSH and vitamin E levels and GSH-Px enzyme activity of hypothermic guinea-pigs were lower (p < 0.05), but SOD enzyme activity was not different (p > 0.05) from those of control animals. Although, the body temperature of hypothermic with vitamin E supplementation group was lower (p < 0.05), all other parameters of this group were not different (p > 0.05) from the controls. It was concluded that oral supplementation of vitamin E can alleviate the lipid peroxidation-induced disturbances associated with hypothermia by increasing the serum vitamin E level to normal. However, more studies are needed to prove whether this vitamin can improve quality of life during the cold seasons.
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PMID:Effect of oral vitamin E supplementation on oxidative stress in guinea-pigs with short-term hypothermia. 1720 Sep 85

Cardiopulmonary bypass (CPB) is associated with oxidative stress. This study examined antioxidant levels in adults undergoing CPB surgery and their correlation with clinical variables. Arterial blood samples were obtained from 27 patients undergoing CPB. The time-course variation of vitamin C (spectrofluorimetry), alpha-tocopherol and retinol (HPLC) levels were determined. Plasma vitamin C rose initially but gradually decayed during reperfusion until 60% reduction of baseline values post-surgery. alpha-Tocopherol and retinol were reduced along CPB with post-operative values approximately 25% lower than baseline. No significant changes were found for selenium and glutathione peroxidase. PaO(2) values rose steadily throughout CPB. A correlation existed for alpha-tocopherol and retinol depletion vs maximal PaO(2) throughout CPB but no correlation was found for antioxidant consumption vs duration of ischaemia and reperfusion and hypothermia level. In conclusion, consumption of arterial blood antioxidant vitamins occurs with CPB in relation with PaO(2) levels but not for other clinical variables measured in this study.
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PMID:Changes in alpha-tocopherol and retinol levels during cardiopulmonary bypass correlate with maximal arterial partial pressure of oxygen. 1772 25

Effects of selenium on reproductive success were assessed in red-winged blackbirds (Agelaius phoeniceus). Mean egg selenium (MES) ranged from 2.96 to 21.7 mg/kg dry weight with individual eggs up to 40 mg/kg. Uptake was non-linear: increments in MES declined as aqueous selenium increased; the asymptote was approximately 23 mg/kg. Eggs were heavier and more were laid in 2004 compared to 2005, a year of record rainfall and below-normal temperatures. Mortality of embryos that were incubated to full term was low (2.6% in 2004 and 3.2% in 2005), as was the prevalence of embryonic defects (2.7% in 2004 and 5.1% in 2005). Abnormalities in nestlings were also rare. Egg mortality was caused by predation, weather, and parental abandonment. Nestlings died from predation, starvation, and hypothermia associated with rain and cold, drowning, and bacterial infections. Nestling liver concentrations reached 81 mg/kg dry wt. selenium and were highest at the most highly selenium-exposed sites. Blood glutathione peroxidase (a selenium-dependent enzyme indicative of selenium exposure) was unrelated to liver selenium concentrations, egg selenium, or ambient selenium exposure. The selenium concentration in prey that parents fed to nestlings was higher at the selenium-exposed sites (up to 37 mg/kg dry wt. Se) compared to reference sites. Aqueous selenate:selenite ratios were related to redox differences and were much higher at the site with the highest MES, liver selenium, and prey item selenium concentrations. Hatchability showed U-shaped, or hormesis, relationships with MES: productivity increased with selenium concentrations at low exposures and decreased at high exposures. The effects threshold was approximately 22 mg/kg dry wt. MES.
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PMID:Non-linear uptake and hormesis effects of selenium in red-winged blackbirds (Agelaius phoeniceus). 1796 20


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