Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Although a role for free radicals in myocardial damage during cardiopulmonary bypass for open heart surgery has been postulated, direct evidence of free radical production as well as consumption of tissue antioxidants such as vitamin E is still lacking. Twenty patients (age 26-66 yr, mean 48) undergoing elective open heart surgery with moderate hypothermia, and cold crystalloid cardioplegia, were studied. Cardiopulmonary bypass time was 61.4 +/- 31.2 min. The specimens of atrial tissue collection before and after cardiopulmonary bypass, were immediately frozen in liquid nitrogen. Mean vitamin E atrial content, measured by reverse phase HPLC, was 355 +/- 249 pmol/mg of dry weight basally, 135 +/- 85 pmol/mg (p < 0.05) at the end of the ischemic period and 405 +/- 288 pmol/mg after the reperfusion period (p < 0.01). Microscopic examination of right atrial biopsies ruled out differences in fibrosis or cellular damage as the cause of vitamin E changes. Although a great basal variability in atrial vitamin E content was observed, which was independent of age, sex and clinical status, a reproducible and substantial decrease in atrial vitamin E content after cardiopulmonary bypass occurred (mean reduction 45 +/- 17% and 55 +/- 22%, respectively, after ischemia and after reperfusion). This was directly related to the aorta cross-clamping duration and partially to the minimum temperature achieved. In conclusion, apart from the great variability observed in basal vitamin E tissue content, vitamin E was always reduced during cardiopulmonary bypass, suggesting an oxidative stress on the myocardium during open heart surgery.
 ...
PMID:Myocardial vitamin E is consumed during cardiopulmonary bypass: indirect evidence of free radical generation in human ischemic heart. 146 17

Functional and structural safety of the myocardium following 6-hour preservation at 4-6 degrees C in ion-balanced cardioplegic solution alone or in combination with pharmacological corrective was evaluated in rats. Langendorff and Neely model of isolated heart perfusion was used. The addition of creatine phosphate in a conservation of 10 mM/l to the solution or donor pretreatment with 70 mg/kg vitamin E was found to potentiate the protective properties of the solution under deep hypothermia. The combined use of the agents proved to warrant the initial intact structural and functional status of the rat myocardium.
 ...
PMID:[Optimal conditions for preservation of isolated heart using creatine phosphate and vitamin E (an experimental study)]. 237 58

The development of osteonecrosis after exposure to altered air pressures is consistent with cellular injury brought about by active oxygen species. The syndrome is considered to arise as a result of an unusual combination of circumstances in which hyperoxia itself, together with the additive responses of the endocrine system to hyperoxia, hypothermia and exertion, each appear to play a part; the net result is thought to increase the mitochondrial generation of superoxide. It is suggested that effective prophylaxis may be possible primarily by establishing a nutritional status that is adequate to ensure that the functional activities of radical-scavenging systems are not hampered by deficiencies either of essential trace elements or of vitamin E. Pharmacological pretreatments designed both to decrease excessive levels of superoxide through increased catalysis of anionic dismutation and to attenuate enzyme-dependent peroxidation may provide an additional line of defence.
 ...
PMID:Dysbaric osteonecrosis (caisson disease of bone): are active oxygen species and the endocrine system responsible, and can control of the production of free radicals and their reaction products confer protection? 333 53

Alopecia (hair loss) is one of the most physically and psychologically distressing side effects of cancer chemotherapeutic drugs. Since its first recognition as a common outcome to most chemotherapeutic agents, only a few trials have been reported, using either a method to temporarily reduce the scalp blood flow (scalp tourniquet or hypothermia) or vitamin E, with undocumented and variable efficacy. The lack of progress in the treatment and prevention of chemotherapy-induced alopecia is in part due to the lack of a reproducible animal model. In the past 2 years, we reported on the following observations: (1) treatment of 8-day-old rats with vidarabine (ara-C), doxorubicin, and cyclophosphamide consistently produced either total body alopecia (ara-C and cyclophosphamide) or alopecia confined to the head and proximal part of the back (doxorubicin); (2) Imuvert, a biologic response modifier derived from the bacterium Serratia marcescens, uniformly produced complete protection against alopecia induced by ara-C and doxorubicin but not that produced by cyclophosphamide; (3) the protective effect of Imuvert against chemotherapy-induced alopecia is mediated by a monocyte-mediated cytokine; and (4) this monocyte-derived cytokine is, possibly, interleukin-1. These observations constitute important progress in the understanding and prevention of chemotherapy-induced alopecia.
 ...
PMID:Chemotherapy-induced alopecia: new developments. 827 35

Major hepatic surgery often requires temporary occlusion of the porta hepatis in order to minimize intraoperative bleeding. Occlusion of porta hepatis induces hepatic ischemia and may cause liver damage. This study was conducted to evaluate the effects of vitamin E, topical hypothermia and administration of steroids on ischemic liver by assessing the hepatic levels of lipid peroxides and examining the ultrastructural change of mitochondria. One hundred and twenty male wistar rats were divided into four groups, each of 30. All rats underwent laparotomy and the liver ischemia experiment was conducted by clamping the porta hepatis for 15 minutes. Group A received no further treatment, group B received vitamin E (30IU/Kg/B.W) supplementation for one week before experiment, group C was topically cooled and group D received preocclusion intravenous methylprednisolone (2mg/Kg/B.W). Hepatic lipid peroxides, expressed as nmol MDA/g wet wt were assessed by spectrofluorometric methods, and were measured immediately before occlusion, 15 min after occlusion, and 15 min after reperfusion. The results showed that the concentration of lipid peroxides increased markedly after occlusion of porta hepatis in group A, which received no treatment in ischemic liver (8.76 +/- 3.19 vs. 10.49 +/- 3.35 MDA nmol/g wet wt, p < 0.05, paired t-test), while the concentrations of hepatic lipid peroxides were not found to increase in groups B, C or D. In the meantime, the ultrastructural study showed marked swelling of mitochondria in ischemic liver of group A rats only. This suggests that vitamin E supplementation, topical hypothermia and administration of steroids will inhibit the propagation of lipid, peroxidation and provide protective effects on liver parenchyma during ischemia.
 ...
PMID:Effect of vitamin E, topical hypothermia and steroid on ischemic liver in rats. 951 83

With the aim of evaluating the effect of interaction between physical training or exercise only during pregnancy and thermal stress on oxidative stress, and antioxidant mechanism sedentary pregnant rats (PS), exercised pregnant rats only during pregnancy (PE) and trained rats submitted to also exercise during pregnancy (PT) were compared (N=63). Exercise sessions consisted of swimming at 80% of maximal work load supported into water at 28 degrees C (hypothermia, PS 28, PE28, PT28) or 35 degrees C (thermal neutrality, PS35, PE35, PT35) or 39 degrees C (hyperthermia, PS39, PE39, PT39), for 30 min. The initial body weight in all groups of rats was from 177 to 207 g. On the 20th day of pregnancy, 24 h after the last immersion or swimming session venous blood was collected to determine oxidative stress. Plasma concentrations of means malondialdehyde (MDA) values measured as thiobarbituric acid reactive substances (TBARS); total glutathione (GSH) and vitamin E were determined. The oxidative stress index was calculated from the ratio TBARS/GSH and TBARS/Vitamin E. TBARS did not change on the group PE at different temperatures of water; TBARS were higher for PS28 than PS35 and PS39; PT35 had higher values than PT28 and PT39. For GSH, PS39 was lower than PS35; PE28 was higher than PE35 and PE39 and PT35 were lower than PT28 and PT39. Plasma concentration of vitamin E did not present any difference for sedentary rats at different water temperatures, but for PE28, the values were lower than for PE35 and PE39, whereas PT39 was lower than PT35 and PT28. In relation to TBARS/GSH, it was verified an increase in oxidative stress for PS28 (in relation to PS35 and PS39), PE35, and PT35 (in relation to PE28 and PE39 or PT28 and PT39); regarding the ratio TBARS/vitamin E, the highest values were obtained at 35 degrees C for PS and PT groups and at 39 for PE group. These results have shown the great complexity of the interaction between physical training, thermal stress and pregnancy. Apparently, hypothermia produces large index of oxidative stress only in sedentary rats, but this index was greater at 35 degrees C in relation to extreme temperatures for trained rats. These results have suggested that physical training allows a more efficient activation of antioxidant mechanisms under thermal stress.
 ...
PMID:Reactive oxygen species in pregnant rats: effects of exercise and thermal stress. 1278 44

Exposure to an extremely cold environment without proper protection leading to hypothermia is an emergency, one of the several complications of which is impairment in nerve conduction. Our previous work in the rat model has shown the beneficial effect of vitamin C in modulating the effect of hypothermia on nerve conduction. The present study aimed to evaluate the effect of vitamins C and E, administered alone or in combination, in modulating the effect of mild hypothermia on human ulnar nerve conduction. The study was carried out on 26 volunteers divided into three groups: group I received vitamin C supplementation (2000 mg/day in a single dose and 1,000 mg/day for the next 6 days), group II received vitamins C and E in combination (1,000 mg and 800 mg respectively in a single dose and 500 mg and 400 mg respectively for the next 6 days) and group III received vitamin E (800 mg in a single dose and the same for the next 6 days). The recordings were carried out before and after single and weekly supplementation in each group. There was a fall in ulnar nerve conduction velocity with a reduction in the oral temperature of 2-2.5 degrees C. Vitamin C administered alone and in combination with vitamin E reduced the fall in ulnar nerve conduction velocity. Prior supplementation with vitamin C and E could help ameliorate the impairment in human ulnar nerve conduction due to hypothermia.
 ...
PMID:Effect of vitamin C and E supplementation in modulating the peripheral nerve conduction following cold exposure in humans. 1282 84

Ultraprofound hypothermia (< 5 degrees C) induces changes to cell membranes such as liquid-to-gel lipid transitions and oxidative stress that have a negative effect on membrane function and cell survival. We hypothesized that fatty acid substitution of endothelial cell lipids and alterations in their unsaturation would modify cell survival at 0 degrees C, a temperature commonly used during storage and transportation of isolated cells or tissues and organs used in transplantation. Confluent bovine aortic endothelial cells were treated with 18-carbon fatty acids (C18:0, C18:1n-9, C18:2n-6, or C18:3n-3), C20:5n-3 or C22:6n-3 (DHA), and then stored at 0 degrees C without fatty acid supplements. Storage of control cells caused the release of lactate dehydrogenase (LDH) and a threefold increase in lipid peroxidation (LPO) when compared to control cells not exposed to cold. Pre-treating cells with C18:0 decreased the unsaturation of cell lipids and reduced LDH release at 0 degrees C by 50%, but all mono- or poly-unsaturated fatty acids increased injury in a concentration-dependent manner and as the extent of fatty acid unsaturation increased. DHA-treatment increased cell fatty acid unsaturation and caused maximal injury at 0 degrees C, which was prevented by lipophilic antioxidants BHT or vitamin E, the iron chelator deferoxamine, and to a lesser extent by vitamin C. Furthermore, the cold-induced increase in LPO was reduced by C18:0, vitamin E, or DFO but enhanced by DHA. In conclusion, the findings implicate iron catalyzed free radicals and LPO as a predominant mechanism of endothelial cell injury at 0 degrees C, which may be reduced by increasing lipid saturation or treating cells with antioxidants.
 ...
PMID:Endothelial cell fatty acid unsaturation mediates cold-induced oxidative stress. 1667 60

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.
 ...
PMID:Effect of oral vitamin E supplementation on oxidative stress in guinea-pigs with short-term hypothermia. 1720 Sep 85

Oxidative stress during cold preservation has been identified as a significant cause of cell injury but the process by which injury occurs is poorly understood. We examined loss of lysosomal integrity as a possible cause of cell injury during extended cold storage of isolated rat hepatocytes. After 21 h of hypothermia, there was a marked decline in lysosomal integrity, which was correlated with an increase in lipid peroxidation. When lipid peroxidation was prevented with the antioxidant Trolox (a vitamin E analog) or the iron chelator desferrioxamine, lysosomal integrity was preserved. In contrast, increasing lysosomal iron with ferric chloride caused an increase in lipid peroxidation and decreased lysosomal integrity. Loss of lysosomal integrity during cold preservation in this experimental model was consistent with iron-initiated oxidative stress. The progressive loss of lysosomal integrity during hypothermic incubation has the potential to affect liver function after transplantation.
 ...
PMID:Oxidative stress causes a decline in lysosomal integrity during hypothermic incubation of rat hepatocytes. 1804 44


1 2 Next >>