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

A series of neurotensin (NT) analogues in which each amino acid has been successively replaced by its D isomer, as well as analogues involving modifications at positions 3 and 11 and a cyclic compound [Cys2,13]-NT, has been synthesized by solid-phase methodology. After purification by conventional techniques the compounds were characterized by thin-layer chromatography, amino acid analysis, and optical rotation. Further characterization of the analogues by high-pressure liquid chromatography demonstrates the high resolving power of this new method. Each analogue was studied for its ability to induce hypothermia in cold-exposed rate (4 degrees C) in vivo and to bind to mast cells in vitro. Although close correlation in potencies was not found for all the analogues tested in both assay systems, they substantiate the basic observation that substitutions in positions 1-9 produced active peptides whereas modification of residues 10-13 considerably decreased biological response in vitro and in vivo. One exception is the higher potency of [D-Phe11]-NT and [D-Tyr11]-NT in vivo. The differences between the efficacies of these analogues in vivo and in vitro are discussed.
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PMID:Neurotensin analogues. Structure--activity relationships. 91 1

The effects of hypothermia on plasma volume (125I-albumin), red blood cell volume (51 Cr-RBC), and capillary permeability (thoracic duct lymph flow and protein concentration) were determined on dogs anesthetized with pentobarbital, paralyzed with succinylcholine, and mechanically ventilated. Red blood cell volume and plasma protein concentration did not change significantly after cooling. Reductions in plasma volume and total plasma proteins indicate that whole plasma was excluded from the effective circulating blood volume. Except for a lesser increase in hematocrit, chronically splenectomized dogs showed essentially the same changes as normal dogs in response to hypothermia. Following application of ice bags, there was a biphasic response in lymph flow. The early increase in lymph flow accompanying a slight decrease in plasma volume was attributable to transcapillary fluid loss into interstitial space, probably due to cold-induced sympathetic activity. The later decrease in lymph flow in hypothermia resulted from a decrease of lymph production secondary to a decrease in available capillary diffusion area. This decrease in lymph flows and the continued reduction in plasma volume suggest an intravascular sequestration of whole plasma.
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PMID:Plasma volume, red cell volume, and thoracic duct lymph flow in hypothermia. 92 Aug 23

Accidental hypothermia may develop within a few minutes by immersion in cold water, in a matter of hours by exposure to cold weather, and in a matter of days in debilitatted victims by continuous exposure to milder cold stress. The prognosis in accidental hypothermia depends on the patient's premorbid condition, the depth and duration of the hypothermia and the degree of exhaustion and metabolic acidosis that result from physiologic attempts to compensate for the heat loss. For deep hypothermia (deep body temperature below 20 C [82.4F]), internal rewarming is strongly recommended as a means of supporting function in body core organs and minimizing the risk of "rewarming shock". For lesser degrees of hypothermia, recoverability depends more on the adequacy of supportive care than on the method of rewarming. The rapid and complete recovery experienced in the case presented is not surprising since the patient's premorbid condition was good, chilling had been rapid, metabolic exhaustion was mild, and internal rewarming was accomplished without delay, using heated peritoneal dialysis.
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PMID:Accidental hypothermia: peritoneal dialysis. 92 14

Lesions in either olfactory bulb or in area postrema modify the amphetamine-induced paradoxical thermoregulatory behavior, although these lesions in no way affect amphetamine-induced hypothermia. In addition, these lesions lead to complicated patterns of thermoregulatory behavior. These results can be best explained by assuming that lesions in one part of the brain monoamine system might affect levels and turnover of monoamines in remote parts of the brain. Among d-amphetamine behavioral effects which are known to be mediated by central dopaminergic neurons are hypothermia in animals placed in a cold environment, and paradoxical thermoregulatory behavior (this involves the movement of animals away from the heating source despite hypothermia). This latter effect requires intact alpha norepinephrine receptors. It seems that neither type of lesion affected dopaminergic neuronal activity in the brain. However, norepinephrine activity in the brain was affected by the area postrema lesion as well as by the olfactory bulb removal.
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PMID:Effects of specific brain lesions on the thermal responses of rats to D-amphetamine. 93 7

Twelve patients who had sustained trauma presented at the emergency department with either asystole or profound hypotension. All underwent thoracotomy and temporary cross clamping of the descending thoracic aorta as part of the resuscitative measures; all received massive amounts of fluids and cold blood and underwent prompt surgical intervention. In none of these patients was there evidence of myocardial, peripheral nerve, neurologic or renal damage. One patient had residual cortical blindness. Measures were taken to preserve renal function before, during and after aortic cross clamping. These included the avoidance of nephrotoxic antibiotics, limit of clamping time to the minimum effective period, intermittent release of the aortic clamp, and intraoperative administration of osmotic diuretics or furosemide, or both. Other factors which may have contributed to these results were the youth of these patients, the absence of cardiac, renal or metabolic diseases and the hypothermia resulting from the administration of large amounts of cold blood. We concluded that temporary cross clamping of the descending thoracic aorta should be performed only for patients with massive exsanguine trauma who have cardiac arrest or who do not respond to other intensive resuscitative measures.
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PMID:Unimpaired renal, myocardial and neurologic function after cross clamping of the thoracic aorta. 94 Oct 82

The "thermoregulatory theory of hunger" posits that rats placed in a cold environment should increase the amount of food intake, while rats placed in a hot environment should decrease their food intake. d-Amphetamine causes hyperthermia among rats kept at warm ambient temperature, and results in hypothermia among animals kept in a cold environment. d-Amphetamine-caused-hyperthermia should therefore result in decreased eating behavior, and d-amphetamine-caused hypothermia should result in increased eating behavior. One must take into account the fact that d-amphetamine is an anorexic drug. The interaction between (a) ambient temperature, (b) body temperature and (c) food intake were tested on groups of rats injected with various doses of d-amphetamine (1.5-15 mg/kg) and placed in ambient temperatures ranging from 4-37 degrees C. No increase in food intake was revealed under any dosage or temperature condition. The decrease in food intake found with d-amphetamine treated animals could not be explained in the "thermoregulatory theory of hunger". Our data indicate that d-amphetamine anorexic effects and thermal effects are mediated by different mechanisms.
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PMID:Interaction effects of d-amphetamine treatment and ambient temperature on rat's food intake. 94 16

In investigating the stress effects of chilling (2-3 degrees C) and hypothermia (2-3 degrees C drop in body core temperature mediated by exposure to hyperbaric helium-oxygen atmosphere) on mouse resistance to "influenza," it was noted that these stresses adversely affected the course of pulmonary infection produced by aerosols of the NWS strain of influenza virus. Comparatively, respiratory LD50 values for control animals were about 25 virus plaque-forming units (PFU) with median mortality occurring on day 13. The LD50 values for mice chilled at 2-3 degrees C were about 15 PFU with median mortality on day 7, and for mice exposed to hyperbaric helium, about 12 PFU with median mortality on day 6. Cold or hyperbaric stress impaired interferon production. Impairment was observed at 24 h but not at 12 h post-challenge and persisted for several days until mice became moribund.
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PMID:Influence of cold or hyperbaric helium-oxygen environments on mouse response to a respiratory viral infection. 97 Nov 54

The effects of changes in ambient and central temperature, amines, PGEu and pyrogen were investigated with respect to the mechanism of Na+-Ca++ ratio in the posterior hypothalamus of the unrestrained cat. Guide tubes were implanted bilaterally above the posterior hypothalamic area of 23 cats so as to accommodate push-pull cannulae. After a Na+ or Ca++ sensitive site was identified by perfusion at 50 mul/min of an artificial CSF containing 10.4 mM excess Ca++ ions or 13.6 mM excess Na+ ions, several types of experiments were undertaken with the results summarized as follows: if the cat was exposed to a cold or warm environmental temperature as the posterior hypothalamus was perfused with excess cation, the typical hypothermia was produced by Ca++ and hyperthermia by Na+ ions. However, if the cat was exposed to peripheral cooling or warming 30 min prior to the perfusion, the fall or rise produced by Ca++ or Na+ was attenuated or prevented. In other experiments, 1.0 muCi 45Ca++ was injected in the ion sensitive site in the posterior hypothalamus to label stores of the cation. Raising of ambient temperature caused a retention of 45Ca++ in this hypothalmic area, whereas a cold environmental temperature enhanced the efflux of 45Ca++ at the same perfusion site. The magnitude of change in 45Ca++ efflux depended upon the intensity of the thermal challenge. Similarly, warming of the anterior hypothalmic, preoptic area by means of implanted thermodes caused an immediate diminution in 45Ca++ efflux in the posterior hypothalamus, whereas cooling of this anterior region augmented the extrusion of 45Ca++ ions from the posterior area. When substances which produce a temperature change were applied to the same thermosensitive zone, the direction of shift in 45Ca++ flux in the posterior area corresponded to the signal for heat production or heat loss. That is, the microinjection of 5-HT, PGE1 or Salmonella typhosa into the anterior hypothalamus enhanced the efflux of 45Ca++ in the posterior hypothalamus as hyperthermia developed, whereas a similar microinjection of norepinephrine reduced the 45Ca++ output from the same sites. Finally, locally anesthetizing the cells of the anterior hypothalamus by the nerve blocker, procaine, prevented the cold and heat-induced 45Ca++ eflux and retention, respectively. These results suggest that if the Na+-Ca++ ratio in the posterior hypothalamus establishes and maintains the set-point for body temperature of 37 degrees -38 degrees C, the mechanism of lability of Ca++ through changes in binding characteristics, transport, or metabolism of the cation serves two purposes: (1) the active defense of the set-point temperature through gradations in ion shifts; and (2) the upward or downward change in set-point value, pathological or normal, triggered by virtue of impulses relayed from the anterior hypothalamus.
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PMID:Hypothalamic Na+ and Ca++ ions and temperature set-point: new mechanisms of action of a central or peripheral thermal challenge and intrahypothalamic 5-HT, NE, PGEi and pyrogen. 97 10

A series of 22 cases of fatal accidental or suicidal hypothermia is presented. Necropsy findings on which the diagnosis can be based were analysed. Purple skin and swelling of face, hands and feet, as well as violet patches on elbows or knees were the most frequent external signs (Frequency 54--59%). The most conspicuous internal macroscopic signs were gastric erosions or haemorrhages, which were seen in half of the cases. Other less frequent signs were pulmonary oedema and acute renal and hepatic degeneration. Microscopically the myocardium showed small degenerative foci and/or fuchsinophilic fibres in two thirds of the cases. The myocardium was macroscopically normal. Histamine and serotonin assays from urine did not indicate increased excretion during exposure. Catecholamine concentrations in urine were high (greater than 0.1 mug/ml) in most hypothermia deaths indicating increased excretion due to cold. The best diagnostic signs seem to be purple skin and oedema in face and ears, stomach erosions, degenerative foci in myocardium and high concentration of catecholamines in the urine.
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PMID:Necropsy findings in fatal hypothermia cases. 97 1

Experimental examinations were performed in 22 dogs to find out the mechanism which leads to a permanent or a reversible damage of the renal parenchyma after normo- and hypothermic ischemia. For this reason the perfusion and the distribution were examined with 133Xe, the vascular changes by angiography, and the parenchymal function with 131I-Hippuran. After normothermic ischemia a short-term reactive hyperemia appeared, which however could not compensate the damage of the renal tubular cells and the resulting excretory insufficiency. After hypothermic ischemia the perfusion was reduced, probably as a consequence of a vasconstriction by cold, however, the function of the tubular cells remained intact, because of the protective mechanism of the hypothermia. The importance of these findings for the development of the so-called "shock-kidney" (acute tubular necrosis) and for the conservative renal surgery in hypothermia is discussed and the application of measures beneficial to perfusion, are suggested.
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PMID:[Changes in perfusion and blood flow distribution following normo- and hypothermic ischemia of the kidneys]. 98 Jul 93


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