Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The course of ischemic increase of extracellular potassium concentration ([K+]e) was studied in rat cerebral cortex with potassium selective microelectrodes and correlated to the preischemic functional and metabolic state. Complete cerebral ischemia was induced in artificially ventilated rats by cardiac arrest. Seven different functional states including conditions with cerebral hypermetabolism (seizures, amphetamine intoxication, hyperthermia) and hypometabolism (barbiturate anesthesia, hypothermia) were chosen in order to cover a wide range of cerebral metabolic rates (CMRO2 : 28.7--2.4 ml O2/(100 g)/min). The ischemic increase of [K+]e was delayed in conditions with low CMRO2 and accelerated in conditions with high CMRO2; the time interval to the terminal steep rise in extracellular potassium concentration varied within the extremes of 35 +/- 5 and 365 +/- 12 sec (means +/- S.E.M.), the control state (N2O-analgesia) being 116 +/- 5 sec. In groups with high CMRO2 electrocortical activity ceased within 15 sec and in groups with low CMRO2 within 22 sec. The rates of the ischemic [K+]e increase, measured as rate of change in the potassium electrode potential (mV/sec), remained high in conditions with high preischemic CMRO2 and low in conditions with low CMRO2, indicating a remaining influence of the preischemic metabolism on membrane ion permeability. These results support previous metabolic data indicating that the rate of consumption of high energy phosphates during ischemia mirrors the preischemic cerebral metabolic rate. Phenobarbital anesthesia did not change the initial rate of [K+]e increase but reduced the rate of [K+]e increase later during ischemia, suggesting a special effect of barbiturates on partly depolarized membranes.
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PMID:The increase in extracellular potassium concentration in the ischemic brain in relation to the preischemic functional activity and cerebral metabolic rate. 740 19

Spontaneous periodic hypothermia is a rare syndrome of recurrent, centrally mediated hypothermia without an identifiable systemic cause or brain lesion. Most patients defend a temporarily lowered temperature "set point" during episodes of hypothermia, despite manifesting many well-known systemic consequences of core temperature hypothermia. No case of death directly attributable to an episode of spontaneous periodic hypothermia has been reported, although many of the serious systemic effects of hypothermia have been documented in these cases, so it is not unlikely that death may occur. The syndrome's cause, and that of Shapiro syndrome, remains unknown. Pharmacologic trials to date have been only modestly successful. Anticonvulsant agents, clonidine, and cyproheptadine appear the most likely to succeed, with cyproheptadine being a reasonable first choice. Given that the term "spontaneous periodic hypothermia" describes a syndrome, and not a pathophysiologic mechanism, it is likely to encompass a common eventuality, arrived at via several different pathways. One can postulate mechanisms such as structural abnormalities, trauma, infection, irritation, and degeneration involving strategic locations which create a focus for epileptic or other periodic dysfunction whose scope involves the centers for thermoregulation. The existence of 2 distinct, oppositional thermoregulatory centers would allow for speculation of similar mechanisms accounting for cases of both periodic hypo- and hyperthermia (61). Postmortem data regarding the hypothalamic and surrounding areas from future cases of Shapiro syndrome and spontaneous periodic hypothermia would be of great interest. Further, more sensitive in vivo testing methods are clearly needed. The role of PET or single photon emission computed tomography (SPECT) with technetium 99m-labeled hexamethylpropylene amine oxime (Tc 99m HMPAO) performed acutely during an episode remains to be characterized (64, 103, 105). The term "diencephalic epilepsy" may in fact be accurate, given the periodic episodes of the case presented here and similar cases resulting from non-generalized seizure activity, with or without an underlying predisposing lesion. The label diencephalic epilepsy has been merely speculative so far, however, as definitive evidence of seizure activity has not been documented. Further, it is expected that the descriptive terms "spontaneous periodic hypothermia" and "episodic spontaneous hypothermia with hyperhidrosis" will outlive their usefulness as researchers gain greater understanding of this syndrome, and be replaced with a more pathophysiologically meaningful nomenclature.
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PMID:Spontaneous periodic hypothermia. 756 67

We report the case of a 9-year-old girl with multiple problems due to hypothalamic dysfunction of obscure origin: apnoeic spells, behavioural problems, developmental delay, hypodipsia with bouts of hypernatraemia, episodes of spontaneous hypothermia, obesity, petit-mal seizures, non-progressive precocious puberty, absence of respiratory response to CO2 and probably insensitivity of hyposensitivity to pain. She also had hyperprolactinaemia and decreased human growth hormone secretion. Hypothyroidism of central origin and hyposecretion of cortisol were also present. Multiple brain CT-scans failed to reveal any tumour or other anatomical abnormality. Her clinical course was improved initially by treatment with clomipramine, but she died suddenly, and the autopsy failed to disclose any anatomical lesion. We compare this case with three similar previously reported cases.
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PMID:Hypothalamic dysfunction in a child: a distinct syndrome? Report of a case and review of the literature. 768 46

The changes in the permeability of the blood-brain barrier during pentylenetetrazol (PTZ)-induced seizures were investigated in normothermic and hypothermic rats. Six groups of rats were studied: (I) normothermic control; (II) hypothermic control; (III) normothermia plus PTZ (80 mg/kg); (IV) normothermia plus PTZ (160 mg/kg); (V) hypothermia plus PTZ (80 mg/kg); (VI) hypothermia plus PTZ (160 mg/kg). The rats were anesthetized with diethyl ether. In the hypothermic animals, colonic temperature was reduced to 20 +/- 1 degree C by submerging the animals in ice water. In normothermic animals, distinct Evans-blue leakage was observed in the occipital cortex, thalamus, hypothalamus, substantia nigra, corpus striatum, and medulla oblongata in both PTZ groups. However, hypothermic animals which received a high dose of PTZ showed the most severe blood-brain barrier breakdown. Mean levels of Evans blue in the brains of low-dose (80 mg/kg) PTZ-treated animals were 8.7 +/- 2.2 micrograms/g and 5.7 +/- 1.4 micrograms/g in the normothermic and hypothermic groups, respectively. This difference was significant (P < 0.01). The levels in the high dose (160 mg/kg) PTZ-treated animals were 10.2 +/- 3.5 micrograms/g and 15.9 +/- 3.6 micrograms/g in the normothermic and hypothermic groups, respectively (P < 0.02). In conclusion, deep hypothermia prevents the blood-brain barrier disruption induced by 80 mg/kg pentylenetetrazol and aggravates the increase in permeability after 160 mg/kg pentylenetetrazol.
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PMID:The effect of profound hypothermia on blood-brain barrier permeability during pentylenetetrazol-induced seizures. 769 98

Eight halogenated derivatives of cannabinol (CBN) substituted on the aromatic ring at the 2 and/or 4 position were synthesized and their pharmacological effects were evaluated by intracerebroventricular injection (50 micrograms/mouse) in mice, using hypothermia, pentobarbital-induced sleep prolongation, catalepsy and anticonvulsant effect as indices. The hypothermic effects of monohalogenated derivatives of CBN were comparable to that of CBN, whereas the effects of dihalogenated derivatives of CBN except for the fluorinated derivative were attenuated. In the interaction with pentobarbital, two monochlorinated derivatives exhibited a significant prolongation of sleeping time, although other derivatives did not significantly affect the sleeping time. The cataleptogenic effects of monofluoro- and 4-bromo-CBN were stronger than that of CBN. 4-Bromo-CBN exhibited a significant prolongation of seizure latency induced by pentylenetetrazol. These data suggest that halogenation of CBN modifies the pharmacological profile of the cannabinoid.
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PMID:Synthesis and pharmacological effects in mice of halogenated cannabinol derivatives. 772 37

The putative cognition enhancer linopirdine (3,3-bis(4-pyrindinylmethyl)-1-phenylindolin-2-one, CAS 105431-72-9) is supposed to act by enhancing the release of neurotransmitters, especially acetylcholine. The present study assessed the effects of a single administration of this compound on the central nervous system in eight different rat and mouse models (CNS general pharmacology). In each test performed, linopirdine was administered subcutaneously in doses of 3, 10, and 30 mg/kg. The compound did not affect traction ability and nociceptive responsiveness nor did it induce catalepsy. Linopirdine impaired motor coordination in the balance rod test. The compound showed a distinct proconvulsive action in the pentylenetetrazole threshold dose test and induced in the highest dose tested (30 mg/kg) lethal seizures in some mice. It increased the duration of hexobarbital-induced anaesthesia in mice. Rats treated with linopirdine showed ptosis, salivation, slight sedation, paw beating and slight hypothermia. These results support the hypothesis that linopirdine acts by elevating the release of different neurotransmitters such as acetylcholine and dopamine. The compound has a low potential to produce side effects at pharmacodynamic active doses.
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PMID:General pharmacology of the putative cognition enhancer linopirdine. 777 41

To explore behavioral selectivity as a consequence of multiple receptor subtypes, four benzodiazepine receptor ligands, flunitrazepam, CGS 9896, zolpidem, and AHR 11797, were tested at five in vivo endpoints: anticonvulsant action, anxiolysis/anxiogenesis as determined in the plus-maze test, locomotor activity, changes in food consumption, and hypothermia. All compounds produced hypothermia. In the plus-maze test, flunitrazepam, CGS 9896, and a low dose of zolpidem (0.05 mg/kg) increased the time spent in the open arms, although AHR 11797 and higher doses of zolpidem decreased time spent in the open arms. Flunitrazepam and zolpidem greatly reduced, CGS 9896 slightly reduced, and AHR 11797 did not affect locomotor activity. Flunitrazepam and CGS 9896 increased food consumption, but AHR 11797 and zolpidem had no effect. Only flunitrazepam fully protected the animals from pentylenetetrazol-induced seizures. The qualitative differences in the effects of these compounds observed are difficult to explain by activation of a single benzodiazepine receptor subtype. As Ro15-1788 antagonized all the observed effects, these compounds act through multiple central benzodiazepine receptors.
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PMID:Evidence for central benzodiazepine receptor heterogeneity from behavior tests. 781 89

1. The behavioural and anticonvulsant effects of eight pyrroloimidazopyridines (PI1a-d and PI2a-d) and four pyrrolopurines (PP) were studied after intraperitoneal administration in DBA/2 mice, a strain genetically susceptible to sound-induced seizures. 2. The anticonvulsant effects were evaluated in DBA/2 mice on seizures evoked by means of auditory stimulation (109 dB, 12-16 kHz) in animals placed singly under a perspex dome. 3. Hypothermic activity was observed after the highest doses of the pyrroloderivatives studied. 4. Our study demonstrated that the anticonvulsant effect of pyrroloimidazopyridines (PI1-7,8,8a,9-tetrahydro-6H-pyrrolo-[1',2':1,2]imidazo[4,5-b]pyrid in-6- ones) and pyrrolopurines (PP) was generally better than corresponding pyrrolobenzimidazoles (PB) and pyrroloimidazopyridines (PI2-5,5a,6,7-tetrahydro-8H-pyrrolo[2',1':2,3]imidazo[4,5-c]pyridin-8- ones) and, in some cases, comparable to that of phenytoin and desmethylclobazam. 5. The anticonvulsant potency of the derivatives studied cannot be directly related to their lipophilicity.
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PMID:Anticonvulsant activity of pyrrolo[1',2':1,2]imidazo[4,5-b]pyridines, pyrrolo[2',1':2,3]imidazo[4,5-c] pyridines and pyrrolo[2,1-f]purines in DBA/2 mice. 783 20

(S)-3-methyl-5-(1-methyl-2-pyrrolidinyl)isoxazole (ABT 418), an isoxazole analog of (-)-nicotine, is a potent agonist at the alpha-4/beta-2 subtype of neuronal nicotinic acetylcholine receptor (nAChR) that exists in mammalian brain (Arneric et al., 1994). Compared to (-)-nicotine, ABT 418 has reduced potency to interact with the subunit isoforms of nAChR found in sympathetic ganglia, and it does not compete for alpha-bungarotoxin binding sites in brain or at the neuromuscular junction. ABT 418 [minimum effective dose (MED), 0.062 mumol/kg i.p.) was 10-fold more potent in improving retention of avoidance learning in normal mice than (-)-nicotine, whereas the (R)-enantiomer of ABT 418, A-81754, was inactive. The memory-enhancing effect of ABT 418 was prevented by the nAChR channel blocker, mecamylamine. In the elevated plus-maze model of anxiety, ABT 418 (MED, 0.19 mumol/kg i.p.) increased open-arm exploration in mice, as previously shown for (-)-nicotine (MED, 0.62 mumol/kg i.p.). A-81754, did not have anxiolytic-like effects in this test. Unlike the classical anxiolytic, diazepam, ABT 418 did not impair rotorod performance in the dose range where beneficial effects occurred. In rats, ABT 418 (MED, 0.002 mumol/kg i.v.) was remarkably potent in enhancing basal forebrain-elicited increases in cortical cerebral blood flow, whereas resting cerebral blood flow was unaffected. Free running cortical electroencephalography in rats was unaffected by ABT 418 at a dose of 1.9 mumol/kg i.p., whereas the same dose of (-)-nicotine caused cortical activation (decreased power in the 1-13 Hz range and increased power in the 25-50 Hz range). Whereas ABT 418 was approximately 3- to 10-fold more potent than (-)-nicotine in memory enhancement and anxiolytic test paradigms, the compound had less emetic liability in dogs as compared to (-)-nicotine, and was less potent than (-)-nicotine in eliciting hypothermia, seizures, death and reduction of locomotor activity in mice. The measured pharmacokinetic or brain disposition properties of ABT 418 in rats did not account for the observed enhancement in efficacy with reduced toxicity as compared to (-)-nicotine. The potent cognitive-enhancing and anxiolytic properties obtained for ABT 418 in animal models without eliciting significant side effects suggest that this ligand is a selective activator of cholinergic channel-mediated behaviors. Thus, ABT 418 may represent a novel, safe and effective treatment of the cognitive and emotional dysfunctions associated with Alzheimer's disease.
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PMID:(S)-3-methyl-5-(1-methyl-2-pyrrolidinyl)isoxazole (ABT 418): a novel cholinergic ligand with cognition-enhancing and anxiolytic activities: II. In vivo characterization. 791 97

The influence of hyperthermia and hypothermia on epileptic brain damage was studied in rats, in which status epilepticus was induced by flurothyl. Histopathological changes were examined by light microscopy after 1 or 7 days of recovery. Two series of animals were studied. In the first, short periods of seizures (20 and 25 min) were employed to examine whether moderate hyperthermia (39.5 degrees C) would aggravate epileptic brain damage, and a longer period (45 min) was used to investigate whether moderate hypothermia (32.5 degrees C) would ameliorate the damage. The second series investigated whether brief periods of status epilepticus (10 min) would cause brain damage if hyperthermia were high or excessive. For this series, animals with body temperatures of 37.0, 39.0, and 41.0 degrees C were studied. Data from normothermic animals (37.5 degrees C) confirmed previously described neuronal damage. Although hyperthermic animals failed to show increased damage in the CA1 sector, or in the hilar region of the dentate gyrus, they showed enhanced damage in the neocortex and globus pallidus (GP). In substantia nigra pars reticulata (SNPR) four out of five hyperthermic animals had bilateral infarcts after 20 min of status epilepticus, whereas no normothermic animal showed such damage. Hypothermia seemed to ameliorate epileptic brain damage in the neocortex (n.s.) and GP (P < 0.05) following status epilepticus for 45 min. Three out of seven hypothermic animals had mild SNPR involvement compared to severe infarction of the nucleus in five out of six normothermic animals (P < 0.05). Thus, hyperthermia aggravated and hypothermia ameliorated epileptic brain damage both in regions showing selective neuronal necrosis (neocortex) and in regions developing pan-necrosis (GP and SNPR). The second series displayed an unexpected result of excessive hyperthermia. Animals subjected to only 10 min of status epilepticus at a temperature of 41 degrees C showed not only neocortical lesions, but also moderate to extensive damage to the hippocampus (CA1, subiculum, and dentate gyrus). It is concluded that at high body and brain temperature, brief periods of status epilepticus can yield extensive brain damage, primarily affecting the hippocampus.
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PMID:Hyperthermia aggravates and hypothermia ameliorates epileptic brain damage. 792 95


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