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)

To study the cerebral protective effects of hypothermia in arterial hypoxia, anesthetized (70% N2O), mechanically ventilated rats were cooled to a body temperature of 27 C. Hypoxia was induced by decreasing the oxygen content in the inspired gas mixture either to 6-7 per cent or to 2.5-3 per cent. This reduced mean PaO2 to about 25 and 11-12 torr, respectively. At PaO2 torr, there was no change in cerebral blood flow (CBF), cerebrla oxygen consumption (CMRO2), or labile tissue metabolites. The absence of signs of cerebral hypoxia could be attributed to an effect of temperature and pH on the hemoglobin-oxygen dissociation curve. Thus, at 27 C with a PaO2 of 25 torr the total oxygen content (TO2) of arterial blood remained greater than 15 ml (100 ml)-1, about three times the value obtained at this PO2 in normothermic rats. At PaO2 11-12 torr, arterial TO2 was reduced to about 5 ml (100 ml) (-1). The hypoxia induced no change in CMRO2, a threefold increase in CBF, a moderate lactacidosis in the tissue, and a small decrease in phosphocreatine content, but no change in ATP, ADP, or AMP. These changes are less marked than those occurring at the same arterial TO2 in normothermic rats. It is concluded that hypothermia exerts a pronounced protective effect on the brain in hypoxic hypoxia, and that two mechanisms are involved. First, since hypothermia shifts the oxyhemoglobin-dissociation curve towards the left, and prevents or minimizes a rightward shift due to acidosis, it maintains a high TO2 in arterial blood at a given PaO2. Second, by reducing CMRO2, and thereby presumably also cellular energy requirements, hypothermia exerts a protective effect at the cellular level.
 ...
PMID:Protective effect of hypothermia in cerebral oxygen deficiency caused by arterial hypoxia. 0 Sep 30

In order to study the relationship between arterial PCO2 and cerebral blood flow (CBF) in hypothermia, the body temperature of artifically ventilated rats was decreased to 22 degreesC, and changes in CBF were evaluated from arteriovenous differences in oxygen content (AVDO2) at PaCO2 values of 15, 30, 40 and 60 mm Hg. The results were compared to those obtained at normal body temperature (37 degrees C) over the PaCO2 range 15-60 mm Hg. Separate experiments were performed to evaluate CBF and CMRO2 at 22 degrees C and a PaCO2 of 15 mm Hg, using an inert gas technique for CBF. The tissue contents of phosphocreatine, ATP, ADP, AMP and lactate were measured in hypothermic animals at PaCO2 values of 15, 30 and 60 mm Hg. The results showed that changes in CBF were of the same relative magnitude in hypothermia and normothermia when PaCO2 was increased from about 35 to about 60 mm Hg. However, with a decrease in PaCO2 the reduction in CBF was much more pronounced in hypothermia, and at PaCO2 15 Mm Hg CBF was less then 20% of the value measured in normothermic and normocapnic animals. The results of the metabolite measurements gave no evidence of tissue hypoxia in spite of the pronounced reduction in CBF. Although the results demonstrate that the brain of a hypothermic animal is protected against the harmful effects of a lowered CBF, it may not warrant recommending hyperventilation in clinical cases of hypothermia, especially not in patients with arteriosclerosis or cerebrovascular diseases.
 ...
PMID:Influence of changes in arterial PCO2 on cerebral blood flow and cerebral energy state during hypothermia in the rat. 0 61

After induction of left ventricular hypertrophy by supravalvar constriction of the ascending aorta in mini pigs (ATP and lactate) were measured under different cardioplegic conditions. In normothermia and plain anoxic arrest ATP decrease and lactate increase were significantly slower in hypertrophied myocardium compared to normal myocardium. Injection cardioplegia using magnesium-aspartate-procaine at 37 degrees C did not influence the ATP decrease and lactate increase in the hypertrophied ventricle, whereas in the normal heart it showed some protection according to these parameters. Optimal ATP preservation and the lowest lactate increase rate were achieved in left ventricular hypertrophy by combined application of magnesium-aspartate-procaine and hypothermia of 25 degrees C. We conclude that normothermic injection cardioplegia has no protective effect on the hypertrophied left ventricle, whereas additional hypothermia can improve magnesium-aspartate-procaine cardioplegia significantly.
 ...
PMID:[The protective effect of magnesium-aspartate-procaine cardioplegia on the hypertrophied left ventricle of the mini-pig (author's transl)]. 15 67

1. Adenosine 3',5'-monophosphate (cAMP), its dibutyryl derivative (Db-cAMP) and other adenine nucleotides have been micro-injected into the hypothalamic region of the unanaesthetized cat and the effects on body temperature, and on behavioural and autonomic thermoregulatory activities observed. 2. Db-cAMP and cAMP both produced hypothermia when applied to the pre-optic anterior hypothalamus. With Db-cAMP the hypothermia was shown to be dose dependent between 50 and 500 mug (0-096-0-96 mumole). 3. AMP, ADP and ATP also produced hypothermia when injected into the pre-optic anterior hypothalamus. 4. The order of relative potencies of the adenine nucleotides with respect both to the hypothermia produced and to the autonomic thermoregulatory effects observed were similar. Db-cAMP was most potent and cAMP least. 5. Micro-injection into the pre-optic anterior hypothalamus of many substances including saline produced in most cats a non-specific rise in body temperature apparently the result of tissue damage. Intraperitoneal injection of 4-acetamidophenol (paracetamol 50 mg/kg) reduced or abolished this febrile response. 6. The hypothermic effect of the adenine nucleotides has been compared with the effects produced in these same cats by micro-injections of noradrenaline, 5-hydroxytryptamine, a mixture of acetylcholine and physostigmine (1:1), EDTA and excess Ca2+ ions. 7. It is concluded that as Db-cAMP and cAMP both produce hypothermia, it is unlikely that endogenous cAMP in the pre-optic anterior hypothalamus mediates the hyperthermic responses to pyrogens and prostaglandins.
 ...
PMID:The effects of cyclic adenosine 3',5'-monophosphate and other adenine nucleotides on body temperature. 17 Mar 96

The influence of elevated and reduced body temperatures upon the metabolic state of the brain was evaluated from the tissue concentrations of phosphocreatine (PCr) ATP, ADP and AMP and from the concentrations of glucose, lactate and pyruvate in immobilized and artificially ventilated rats anesthetized with 70% N2O. The results were compared to the results obtained in normothermic animals. It was found that rats with body temperatures of 32 degrees and 22 degrees C had the same brain tissue concentrations of high energy phosphates and the same adenylate energy charge as the controls, but hypothermia led to a progressive decrease of both cerebral and arterial lactate and pyruvate concentrations. A metabolic acidosis but no excess lactate appeared in the blood. At a body temperature of 42 degrees C, the metabolic pattern in the brain agreed with a state of hypoxia at a time when there was no sign of substrate depletion. Arterial blood showed excess lactate which may indicate an inadequacy of the oxygen supply also to other tissues.
 ...
PMID:Effects of hypothermia and hyperthermia on brain energy metabolism. 24 Nov 93

This is a report a a new system for freezing human red blood cells in the same polyvinyl chloride plastic container in which the blood is collected and separated into components. This polyvinyl chloride plastic collection bag with integrally attached transfer packs for blood collection, component separation, red blood cell biochemical modification, freezing, storage, and post-thaw dilution before washing, represents a major advancement in the freeze-preservation process. The label with the donor's blood type and identification number affixed to the bag at the time of collection remains in place throughout the freezing and thawing process. The transfused red blood cells are of superior quality, and the processing cost is less than with other methods of freeze-preservation. There is a lower risk of contamination with these red blood cells because manipulation of the product is kept at a minimum. "Rejuvenation", a bioengineering process by which outdated red blood cells can be salvaged, can be incorporated into the preservation process using one of the attached transfer packs of the primary collection bag. This process has been introduced as a possible means of alleviating the dramatic blood shortages which occur periodically. Red blood cells may also be "rejuvenated" after storage in the liquid state to increase their 2,3 DPG and ATP levels to 150 to 200% of normal, and these red blood cells with improved oxygen transport function have been administered to anemic patients with and without cardiopulmonary insufficiency, patients undergoing cardiopulmonary bypass and treatment with hypothermia during cardiac surgery, and in instances where nonhemolytic transfusion reactions might be expected.
 ...
PMID:Human red blood cells with normal or improved oxygen transport function prepared and frozen in the primary polyvinyl chloride plastic blood collection container. 39 73

The clinical results with cardioplegic solutions and hypothermia during aortic cross-clamping are compared with the clinical results obtained with hypothermia only. To complete the study miocardial biopsies were obtained during aortic cross-clamping in order to evaluate the concentration of ATP and CPK. The obtained data confirm the effectiveness of the myocardial protection.
 ...
PMID:[Myocardial protection from cardioplegic and hypothermia during aortic cross-clamping (author's ttrans)]. 45 88

To determine the protective effects of different methods of cardioplegia, studies on ATP/lactate levels and ultrastructure were performed in human papillary muscles obtained during mitral valve replacement. In group I (n = 5), plain ischemic arrest in hypothermia (systemic venous temperature = 24 degrees C) was accomplished. In group II (n =12), the heart was arrested by injection cardioplegia using magnesium-aspartate-procaine at systemic venous and myocardial temperatures of 24 degrees C. In group III (n = 12) Bretschneider infusion cardioplegia at systemic venous and myocardial temperatures of 26 degrees C and 19 degrees C respectively was applied. With regard to ultrastructural changes there were no clearcut differences in the three methods of hypothermic cardiac arrest after 60 minutes of ischemia. Ischemic changes tended to be slightest in group III (infusion cardioplegia). ATP decay and lactate increase were significant in group I and moderate to minimal in groups II and III after the same period of time. It is concluded that for aortic cross-clamp times up to 60 minutes, body hypothermia and injection cardioplegia using magnesium-aspartate-procaine at a myocardial temperature of 24 degrees C provide adequate protection of the myocardium. For ischemia times beyond 70 minutes, profound myocardial hypothermia below 20 degrees C is preferred.
 ...
PMID:Ultrastructural and biochemical changes of human papillary heart muscle during different methods of induced cardiac arrest. 49 22

Sudden hypothermia utilising liquid nitrogen has been used for immediate inhibition of metabolic reactions and preservation of labile compounds in heart muscle. It has been suggested that this rapid transfer of tissue into liquid nitrogen, within 1 to 2 s, is essential for accurate assessment of internal milieu conditions. We tested this hypothesis in normal dogs by measuring phosphocreatin, ATP, glycogen, and lactate concentrations in transmural layers of a core biopsy taken from the posterolateral wall of the left ventricle frozen immediately in liquid nitrogen or held at room temperature for varying times up to 300 s before freezing the tissue. The earliest significant change occurred in phosphocreatine levels after 60 s; only phosphocreatine demonstrated any changes within the first 120 s. These studies indicate that a delay of up to 30 s may be tolerated before freezing tissue without any change occurring in these labile metabolites.
 ...
PMID:Effects on labile metabolites of temporal delay in freezing biopsy samples of dog myocardium in liquid nitrogen. 64 20

In 53 patients with mitral- or aortic-mitral valve disease, the content of ATP and lactate of the papillary muscles resected at the time of valve replacement was investigated at the beginning of ischemic arrest and at the time of reperfusion. Profound body hypothermia (25 degrees C) and injection cardioplegia using magnesium-aspartate-procaine were applied for myocardial protection. In hypertrophic papillary muscles the myocardial ATP content decreased at a slower rate (ATP decay 12% of the initial value after 60 minutes of ischemia) than in normal papillary muscles obtained from patients with isolated mitral stenosis (ATP decay 33% of the initial value after 40 minutes of ischemia). 20% of the patients required temporary inotropic circulatory support postoperatively for 12 to 88 hours. The ATP content of the papillary muscles of these patients differed only little from those, in who no myocardial failure occurred. However the myocardial lactate levels were higher in patients in whom a low cardiac output state evolved.
 ...
PMID:[Behaviour of ATP and lactate in human papillary muscle during profound hypothermia and injection cardioplegia with magnesium-asparatate-procaine (author's transl)]. 75 Dec 88


1 2 3 4 5 6 7 8 9 10 Next >>