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

The ontogeny of GABAergic enhancement of generalized absence seizures was examined in the gamma-hydroxybutyrate (GHB) model of generalized absence seizures. The GHB seizure was quantitated in developing and adult rats in the presence of varying doses of the GABAa agonist muscimol or intracerebroventricularly (i.c.v.) administered GABA. Both GABA and muscimol potentiated GHB-induced seizures in an age-dependent fashion. The adult dose of 1 mg/kg muscimol was extremely potent in rats less than 28 days of age and resulted in the death of all younger animals tested secondary to profound hypothermia. A dose of 0.1 mg/kg muscimol was associated with a significant prolongation of GHB seizure in rats less than 35 days of age, but had no effect on older animals. The response to GHB was also age dependent, with the greatest sensitivity occurring during the fourth and fifth week of life. The developmental sensitivity of the rat to GHB seizure correlated with enhancement of the seizure by muscimol and GABA, and both phenomena parallel the maturation of thalamocortical recruiting mechanisms thought to play a role in the pathogenesis of the bilaterally synchronous spike wave discharges that characterize generalized absence seizures.
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PMID:The ontogeny of GABAergic enhancement of the gamma-hydroxybutyrate model of generalized absence seizures. 236 73

Birth asphyxia is frequent and often severe, occurring in about 10% and 1% respectively of all births; in a third it is unexpected. Delivery rooms must be organised and equipped and trained staff readily available so as to provide appropriate and timely resuscitation of the newborn. Simple procedures designed to prevent hypothermia, maintain a patent airway, improve oxygenation and ventilation are sufficient for the majority of babies. Circulatory support and biochemical resuscitation will be needed in a few. In the absence of other abnormalities, the long term prognosis for newborns who respond promptly to resuscitation is good. Every baby, no matter how severely asphyxiated must therefore be promptly and vigorously resuscitated. Only those with a Apgar score of less than 4 at 10 minutes, prolonged hypotonia or seizures have a poor prognosis. With the needs in cardio-pulmonary resuscitation understood and met, research is now being directed at neuroresuscitation.
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PMID:Resuscitation at birth. 237 83

We conducted a retrospective review of 55 near-drowning victims (mean age 4.75 years) admitted to the intensive care unit during a 5-year period, to determine the factors that may influence survival both before and after hospital admission. All patients who remained comatose after resuscitation received ventilation for an initial 24 hour period, after which an assessment of central nervous system injury was made. Intracranial pressure was not monitored, and barbiturate therapy was used only for seizure control. Thirty-seven children survived and 18 died; five survivors had profound neurologic damage resulting in a persistent vegetative state: the remaining 32 (58%) survived intact. The major factors that separated intact survivors from those who died and from survivors in a persistent vegetative state were the presence of a detectable heartbeat and hypothermia (less than 33 degrees C) on examination in the emergency department. Thirteen patients with absent vital signs and a temperature of greater than 33 degrees C either died or survived in a persistent vegetative state. Fourteen patients had a combination of absent vital signs and hypothermia and were resuscitated; eight died, two survived in a persistent vegetative state, and four survived intact. All intact survivors had been submerged in cold water for prolonged periods, and all underwent prolonged cardiopulmonary resuscitation. All patients with a detectable pulse, regardless of temperature, survived without neurologic sequelae. The 58% intact survival rate in this series compares favorably with the 50% we reported previously when high-dose barbiturate therapy and hypothermia were used to control intracranial pressure; at the same time, the number of survivors with a persistent vegetative state has been reduced by 50%. We conclude that prolonged in-hospital resuscitation and aggressive treatment of near-drowning victims who initially have absence of vital signs and are not hypothermic either results in eventual death or increases the number of survivors with a persistent vegetative state.
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PMID:Effect of hypothermia and cardiac arrest on outcome of near-drowning accidents in children. 238 Aug 13

Brain-stem auditory evoked potentials (BAEPs) were recorded from young alligators (Alligator mississippiensis), and the effects of hypothermia, hyperthermia and hypoxia on the wave forms were determined. The wave form shape was similar to the human BAEP, although extra waves were routinely seen. The responses were highly repeatable and varied in a predictable manner as a function of stimulus frequency, polarity, intensity, and body temperature. Rarefaction clicks produced longer wave form latencies than condensation clicks. BAEPs were present over the entire temperature range studied (0-36 degrees C). In contrast, mammalian BAEPs disappear over the temperature range of 20-27 degrees C, and seizures occur at 20-21 degrees C. At temperatures below 20 degrees C, the alligator BAEP peak amplitudes decreased with decreased temperature, but latencies only decreased slightly. At temperatures above 20 degrees C the peak amplitudes increased, and the latencies decreased with temperature. Peak I was largely unaffected by temperature change, while peaks IIIa and V increased 0.015 and 0.018 msec/degree C, respectively, at temperatures above 24 degrees C. Transient brain hypoxia, achieved by inverting the alligator, produced a progressive decrease in BAEP waves to an isoelectric amplitude without greatly altered latencies. The reverse sequence of changes was seen during recovery. Postural effects on blood flow were documented in two alligators with implanted flow probes. Carotid artery blood flow decreased 43% with body inversion, in both anesthetized and unanesthetized alligators, but no sequelae from the hypoxia could be detected. Metabolic differences between mammals and the alligator may account for the alligator's resistance to hypothermia, hyperthermia and hypoxia.
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PMID:Brain-stem auditory evoked potentials in the alligator. Effects of temperature and hypoxia. 243 83

Because hypothermia and anorexia were previously found to be more sensitive indices of the effects of lindane than were convulsions, these endpoints were used to quantify the ability of benzodiazepines (BDs) and phenytoin either to ameliorate or exacerbate the toxicity of lindane in the rat. After administration of lindane (40 or 50 mg/kg) in oil per os, toxicity was counteracted by phenytoin and the "central" BD agonists diazepam and clonazepam, but was worsened by Ro 5-4864 a "peripheral" BD agonist. Clonazepam and diazepam were each more effective in counteracting lindane-induced anorexia than in stimulating food intake, presumably because the animals had been fasted and probably even controls ate maximally when food was presented. Diazepam alone (3 injections in 1 day) produced withdrawal-induced decreased food intake the following day. Clonazepam and diazepam alone each transiently decreased colonic temperature, yet effectively blocked the more severe hypothermia produced by lindane. Ro 5-4864 by itself did not produce any measurable effects, yet exacerbated all of the effects, including lethal effects, of lindane. The present findings are compatible with other evidence that lindane and Ro 5-4864 act at the picrotoxinin receptor of the GABAA-activated chloride channel and that systemic administration of agents acting at this site may produce a constellation of effects, including seizures, hypothermia and anorexia.
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PMID:"Central" and "peripheral" benzodiazepines and kinetics of lindane-induced toxicity. 247 Dec 14

Genetic influences on the interaction between ethanol (ETOH) and gamma-aminobutyric acid (GABA) neurotransmitter systems were evaluated with a survey of responses to coadministration of ETOH and a GABA antagonist, bicuculline, in a battery of inbred mouse strains. The selectively bred ETOH-sensitive Long-Sleep (LS) mice, the relatively ETOH-resistant Short-Sleep (SS) mice, and a genetically heterogeneous stock (GHS) were also evaluated. The effect of bicuculline on ETOH-induced sedation, hypothermia, and blood ethanol content upon recovery from sedation was assessed. Inheritance of these responses was also examined using F1 hybrids. The effect of bicuculline on ETOH-produced narcosis varied widely among stocks and included antagonism, potentiation, and no effect. Changes in ETOH-induced narcosis produced by bicuculline were accompanied by changes in blood ethanol concentrations consistent with an hypothesis of altered central nervous system sensitivity to ETOH. Knowledge of a strain's seizure susceptibility to the GABA antagonist or of its sensitivity to the hypnotic effects of ETOH were of no predictive value in estimating the outcome of coadministration studies, suggesting at least partially separate genetic influences on each phenotype. In cross-breeding studies there was commonly dominance toward a profile of bicuculline antagonism of ETOH narcosis but different patterns of dominance were observed for seizure susceptibility, again indicating separate genetic control. The results suggest considerable complexity of GABAergic involvement in genotype-dependent ETOH sensitivity.
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PMID:Modification of ethanol effects by bicuculline: genotype-dependent responses and inheritance. 250 98

The cocaine sensitivity of male and female long-sleep (LS) and short-sleep (SS) mice, which have been selectively bred for differential ethanol-induced "sleep-time," was examined in a battery of behavioral and physiological tests. Differences between these two mouse lines were subtle and were seen primarily at high doses. At high doses, SS mice were more sensitive than LS mice, particularly to cocaine-induced hypothermia; however, significant hypothermia was not seen except at doses which were very near to the seizure threshold. During a 60-min test of locomotor activity, LS mice showed greater stimulation of Y-maze activity by 20 mg/kg cocaine than SS mice. Consistent with the finding of subtle differences in sensitivity to low doses of cocaine. LS and SS mice did not differ in sensitivity to cocaine inhibition of synaptosomal uptake of [3H]-dopamine, [3H]-norepinephrine or [3H]-5-hydroxytryptamine. However, consistent with the finding of differential sensitivity to high doses of cocaine, SS mice were more sensitive to the seizure-producing effects of the cocaine and lidocaine, a local anesthetic. It is hypothesized that the differential sensitivity of these mouse lines to high doses of cocaine is due to differential sensitivity to cocaine's actions on systems that regulate local anesthetic effects. Selective breeding for differential duration of alcohol-induced "sleep-time" may have resulted in differential ion channel structure or function in these mice.
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PMID:Differential sensitivity of long-sleep and short-sleep mice to high doses of cocaine. 262 42

Over a period of one year, 16,365 consecutively live born neonates were prospectively studied for evidence of birth asphyxia using the requirement of greater than one minute of positive pressure ventilation for identifying infants suffering from birth asphyxia. Asphyxia occurred in 2.8% of all neonates. Multivariate analysis of high risk factors associated with increased risk of asphyxia showed that low birth weight was the most significant predictor of asphyxia: asphyxia occurred in 68% of infants of less than 1,000 g birth weight and decreased to 1.2% in infants of 3-4 kg birth weight. Perinatal risk factors associated with a higher incidence of asphyxia include: postmaturity, birth weight (less than or equal to 2.5 kg) and with the presence of maternal and/or obstetric complications. The impact of asphyxia on neonatal mortality was most pronounced in more mature infants and the mortality was increased 3 fold in infants of less than 34 week gestation and greater than 27 fold for infants greater than 38 week gestation. Of the asphyxiated neonates, intrauterine growth retardation, fetal macrosomia, hypothermia, hyaline membrane disease, seizures, hypoglycemia and hyponatremia were significantly associated with an increased risk of death.
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PMID:Perinatal risk factors in birth asphyxia: relationship of obstetric and neonatal complications to neonatal mortality in 16,365 consecutive live births. 262 78

One hundred children with meningococcal infection diagnosed from January 1, 1985, to February 29, 1988, were reviewed. Clinical manifestations ranged from fever alone to fulminant septic shock with purpura fulminans. Twenty-nine percent of the children presented without skin lesions. Of the 55 patients with meningitis, 6 lacked cerebrospinal fluid abnormalities on initial lumbar puncture but cerebrospinal fluid cultures were positive. An overall case fatality rate of 10% was noted with the following poor prognostic indicators identified: hypothermia; seizures or shock on presentation; a total peripheral white blood cell count less than 5000/mm3; a platelet count less than 100,000/mm3; and the development of purpura fulminans. Meningococcal infections remain an important cause of morbidity and mortality in children. Infections caused by Neisseria meningitidis (including meningitis) should be considered even in the absence of skin lesions or cerebrospinal fluid abnormalities.
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PMID:Meningococcal infections in children: a review of 100 cases. 265 60

The management and evaluation of neurosurgical intracranial catastrophes require a multidisciplinary approach to optimize outcome. Intracranial pathology must be rapidly evaluated. Clinically, the patient's mental status, the degree and extent of focal neurologic deficits, and the dynamic nature of any changes in clinical status are assessed. The CT scan is invaluable for diagnosing and monitoring the progress and extent of intracranial pathology. Medical therapy for the control of intracranial hypertension must be undertaken simultaneously. This begins with provision of an adequate, protected airway and support of cardiopulmonary function. Specific measures to control intracranial hypertension include hyperventilation, osmotherapy, CSF removal, seizure control, autonomic control, sedation (primarily thiopental), muscle relaxation, mild hypothermia, and, if indicated, steroids. The goal of intraoperative management is physiologic support of systemic and cerebral hemodynamics. There should be a smooth transition from the discovery of the patient in extremis through the period of medical stabilization, operative intervention, and ultimate delivery of the patient to the intensive care facility for extended treatment.
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PMID:Perioperative management of intracranial catastrophes. 267 2


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