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

Hot, humid conditions in tropical regions generally rule out any risk of hypothermia due to cold exposure. In this report, we describe a case of severe hypothermia involving a core temperature of 26 degrees C in a 61-year-old man living in Gabon. Parkinson's disease and chronic alcoholism may have been predisposing factors. The patient was treated by active and passive rewarming (intestinal irrigation with warm water). Sudden circulatory collapse occurred during treatment but the final outcome was successful. This case demonstrates that hypothermia can occur in tropical areas. Emergency diagnosis may be difficult in Black Africa where adequate temperature monitoring equipment is rarely available. Standard mercury thermometers do not allow measurement of temperatures lower than 34 degrees C. African physicians should be aware of the possibility of potentially life-threatening hypothermia and be prepared to initiate proper treatment and surveillance in intensive care.
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PMID:[Severe hypothermia in a tropical setting]. 979 96

Muscarinic acetylcholine receptors (M(1)-M(5)) regulate many key functions of the central and peripheral nervous system. Primarily because of the lack of receptor subtype-selective ligands, the precise physiological roles of the individual muscarinic receptor subtypes remain to be elucidated. Interestingly, the M(4) receptor subtype is expressed abundantly in the striatum and various other forebrain regions. To study its potential role in the regulation of locomotor activity and other central functions, we used gene-targeting technology to create mice that lack functional M(4) receptors. Pharmacologic analysis of M(4) receptor-deficient mice indicated that M(4) receptors are not required for muscarinic receptor-mediated analgesia, tremor, hypothermia, and salivation. Strikingly, M(4) receptor-deficient mice showed an increase in basal locomotor activity and greatly enhanced locomotor responses (as compared with their wild-type littermates) after activation of D1 dopamine receptors. These results indicate that M(4) receptors exert inhibitory control on D1 receptor-mediated locomotor stimulation, probably at the level of striatal projection neurons where the two receptors are coexpressed at high levels. Our findings offer new perspectives for the treatment of Parkinson's disease and other movement disorders that are characterized by an imbalance between muscarinic cholinergic and dopaminergic neurotransmission.
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PMID:Enhancement of D1 dopamine receptor-mediated locomotor stimulation in M(4) muscarinic acetylcholine receptor knockout mice. 1053

(R)-apomorphine is a non-selective dopamine (DA) agonist which is used in the treatment of Parkinson's disease. In addition to symptomatic effects, apomorphine exerts a neuroprotective activity in specific experimental models. For instance, apomorphine prevents experimental parkinsonism induced by the neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine. Neuroprotection obtained with apomorphine does not seem to be related to its dopamine (DA) agonist properties, instead it appears to be grounded on the antioxidant and the free radical scavenging effects of the compound. In this study, we sought to determine whether apomorphine protects against methamphetamine toxicity. We found that apomorphine (1; 5 and 10 mg/kg) dose-dependently protects against methamphetamine- (5 mg/kg X3, 2 h apart) induced striatal DA loss and reduction of tyrosine hydroxylase (TH) activity in the rat striatum. These protective effects are neither due to a decrease in the amount of striatal methamphetamine nor to hypothermia as indicated by measurement of striatal methamphetamine and body temperature at different time intervals after drug administration. The effects of apomorphine were neither opposite to, nor reversed by the DA antagonist haloperidol despite no decrease in body temperature was observed when apomorphine was given in combination with haloperidol. The present data are in line with recent studies suggesting a DA receptor-independent neuroprotective effect of apomorphine on DA neurons and call for further studies aimed at evaluating potential neuroprotective effects of apomorphine in Parkinson's disease.
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PMID:Dose-dependent protective effects of apomorphine against methamphetamine-induced nigrostriatal damage. 1129 46

Apomorphine, given by a single injection, repeated injections, or by continuous infusion, was tested for neuroprotective effects in mice administered methamphetamine or N-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in order to induce striatal dopamine (DA) depletion. In the first part of the study, the DA agonist (R)-apomorphine was administered at various doses (1, 5, and 10 mg/kg), 15 min before methamphetamine (5 mg/kg x 3, 2 h apart). Mice were sacrificed 5 days later. In the second part, apomorphine was administered either continuously by subcutaneous minipump (cumulative daily dose of 0.5, 1, and 3.15 mg/kg), or as single, repeated daily injections (up to 5 mg/kg) starting 40 h after an acute administration of MPTP (30 mg/kg). Mice were sacrificed at different time intervals (up to 1 month) following MPTP injection. In all the animals, the integrity of striatal DA terminals was evaluated by measuring striatal DA levels and TH immunohistochemistry. Apomorphine dose-dependently prevented methamphetamine toxicity. These effects were neither due to a decrease in the amount of striatal methamphetamine nor to the hypothermia, and they were not reversed by the DA antagonist haloperidol. Moreover, chronic, continuous (but not pulsatile) administration of apomorphine rescued damaged striatal dopaminergic terminals. These findings confirm a protective effect of apomorphine that also consists of a neurorescue of damaged striatal DA terminals. This suggests a new hypothesis about the long-term benefits observed during continuous apomorphine administration in Parkinson's disease patients.
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PMID:Morphological and biochemical evidence that apomorphine rescues striatal dopamine terminals and prevents methamphetamine toxicity. 1210 1

Dopamine constitutes about 80% of the content of central catecholamines and has a crucial role in the etiology of several neuropsychiatric disorders, including Parkinson's disease, depression and schizophrenia. Several dopaminergic drugs are used to treat these pathologies, but many problems are attributed to these therapies. Within this context, the search for new more efficient dopaminergic agents with less adverse effects represents a vast research field. The aim of the present study was to report the structural design of two N-phenylpiperazine derivatives, compound 4: 1-[1-(4-chlorophenyl)-1H-4-pyrazolylmethyl]-4-phenylhexahydropyrazine and compound 5: 1-[1-(4-chlorophenyl)-1H-1,2,3-triazol-4-ylmethyl]-4-phenylhexahydropyrazine, planned to be dopamine ligands, and their dopaminergic action profile. The two compounds were assayed (dose range of 15-40 mg/kg) in three experimental models: 1) blockade of amphetamine (30 mg/kg, ip)-induced stereotypy in rats; 2) the catalepsy test in mice, and 3) apomorphine (1 mg/kg, ip)-induced hypothermia in mice. Both derivatives induced cataleptic behavior (40 mg/kg, ip) and a hypothermic response (30 mg/kg, ip) which was not prevented by haloperidol (0.5 mg/kg, ip). Compound 5 (30 mg/kg, ip) also presented a synergistic hypothermic effect with apomorphine (1 mg/kg, ip). Only compound 4 (30 mg/kg, ip) significantly blocked the amphetamine-induced stereotypy in rats. The N-phenylpiperazine derivatives 4 and 5 seem to have a peculiar profile of action on dopaminergic functions. On the basis of the results of catalepsy and amphetamine-induced stereotypy, the compounds demonstrated an inhibitory effect on dopaminergic behaviors. However, their hypothermic effect is compatible with the stimulation of dopaminergic function which seems not to be mediated by D2/D3 receptors.
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PMID:Dopaminergic profile of new heterocyclic N-phenylpiperazine derivatives. 1271 82

Autonomic dysfunction in patients with Parkinson's disease has been recognized since the original description by James Parkinson in 1817. In the present case, an 80-year-old woman who had been diagnosed with Parkinson's disease 3 years earlier (Hoehn and Yahr stage III) was admitted with a few days history of lethargy and bradykinesia. She lived in a heated house and used an electric blanket at night. On examination, her core temperature was 29.7 degrees C. Her initial ECG showed sinus bradycardia, QT prolongation, and Osborn waves, which disappeared after rewarming. Successful rewarming was achieved with an external rewarming blanket over 12 hours. Follow-up ECG showed resolution of the Osborn waves. In Parkinson's disease, rapidly progressive hypothermia can occur in a well-heated house. Determining a rewarming strategy is a complex but not insurmountable task. In the elderly, the use of careful active external rewarming and a low stress strategy may be recommended.
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PMID:Hypothermia with Osborn waves in Parkinson's disease. 1936 59

While brain free magnesium levels have been shown to decline in a number of acute and chronic brain pathologies, the mechanisms of such decline and the potential for magnesium administration as a therapeutic intervention are still unclear. In acute brain injury, magnesium therapy has failed in recent clinical trials of trauma, presumably because of an intact blood brain barrier at the time of administration reducing central penetration. Under such conditions, magnesium's peripheral effects on cardiovascular parameters may dominate over the central, and potentially neuroprotective, effects of the compound. In contrast, magnesium has been demonstrated to be beneficial in lacunar strokes, albeit that recent animal studies indicate that this effect is without any significant reduction of lesion size. Postnatal magnesium has also been shown to improve neurological outcome in term neonates with perinatal asphyxia, although this may be limited to cases of mild to moderate brain injury; no effect is observed following severe brain injury. Prenatal magnesium has been reported to be beneficial for outcome in very preterm infants, although this may only be at low doses. Combination therapies are also showing promise in experimental studies, with combined magnesium and mild hypothermia as well as magnesium and polyethylene glycol proving effective in ischemic stroke and in spinal cord injury, respectively. With respect to chronic brain injury, recent results indicate that magnesium deficient mice are susceptible to developing Parkinson's disease, which is consistent with earlier findings that magnesium deficiency over a number of generations is associated with the development of Parkinson's disease. The latter was associated with the appearance of variants of the TRPM channels. Our recent studies have shown that Parkinson's disease is associated with reduced TRPM2 and TRPM7 channel mRNA expression. Taken together, a more complete picture is emerging of the role of magnesium in brain injury, its therapeutic potential as well the mechanisms associated with its decline.
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PMID:Magnesium in acute and chronic brain injury: an update. 1978 Apr 2

Methamphetamine is a synthetic drug consumed by millions of users despite its neurotoxic effects in the brain, leading to loss of dopaminergic fibres and cell bodies. Moreover, clinical reports suggest that methamphetamine abusers are predisposed to Parkinson's disease. Therefore, it is important to elucidate the mechanisms involved in methamphetamine-induced neurotoxicity. Dopamine receptors may be a plausible target to prevent this neurotoxicity. Genetic inactivation of dopamine D1 or D2 receptors protects against the loss of dopaminergic fibres in the striatum and loss of dopaminergic neurons in the substantia nigra. Protection by D1 receptor inactivation is due to blockade of hypothermia, reduced dopamine content and turnover and increased stored vesicular dopamine in D1R(-/-) mice. However, the neuroprotective impact of D2 receptor inactivation is partially dependent on an effect on body temperature, as well as on the blockade of dopamine reuptake by decreased dopamine transporter activity, which results in reduced intracytosolic dopamine levels in D2R(-/-) mice.
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PMID:The role of dopamine receptors in the neurotoxicity of methamphetamine. 2360 Mar 99

Preconditioning is a phenomenon in which brief episodes of a sublethal insult induce robust protection against subsequent lethal injuries. Preconditioning has been observed in multiple organisms and can occur in the brain as well as other tissues. Extensive animal studies suggest that the brain can be preconditioned to resist acute injuries, such as ischemic stroke, neonatal hypoxia/ischemia, surgical brain injury, trauma, and agents that are used in models of neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease. Effective preconditioning stimuli are numerous and diverse, ranging from transient ischemia, hypoxia, hyperbaric oxygen, hypothermia and hyperthermia, to exposure to neurotoxins and pharmacological agents. The phenomenon of "cross-tolerance," in which a sublethal stress protects against a different type of injury, suggests that different preconditioning stimuli may confer protection against a wide range of injuries. Research conducted over the past few decades indicates that brain preconditioning is complex, involving multiple effectors such as metabolic inhibition, activation of extra- and intracellular defense mechanisms, a shift in the neuronal excitatory/inhibitory balance, and reduction in inflammatory sequelae. An improved understanding of brain preconditioning should help us identify innovative therapeutic strategies that prevent or at least reduce neuronal damage in susceptible patients. In this review, we focus on the experimental evidence of preconditioning in the brain and systematically survey the models used to develop paradigms for neuroprotection, and then discuss the clinical potential of brain preconditioning.
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PMID:Preconditioning provides neuroprotection in models of CNS disease: paradigms and clinical significance. 2438 80

Electrocardiographic artifacts are defined as electrocardiographic alterations, not related to cardiac electrical activity. As a result of artifacts, the components of the electrocardiogram (ECG) such as the baseline and waves can be distorted. Motion artifacts are due to shaking with rhythmic movement. Examples of motion artifacts include tremors with no evident cause, Parkinson's disease, cerebellar or intention tremor, anxiety, hyperthyroidism, multiple sclerosis, and drugs such as amphetamines, xanthines, lithium, benzodiazepines, or shivering (due to hypothermia, fever (rigor due to shaking), cardiopulmonary resuscitation by chest compression (oscillations of great amplitude) and patients who move their limbs during the test, causing sudden irregularities in the ECG baseline that may resemble premature contractions or interfere with ECG wave shapes, or other supraventricular and ventricular arrhythmias. When the skeletal muscles experience shaking, the ECG is "bombarded" by apparently random electrical activity.
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PMID:Main artifacts in electrocardiography. 2894 Sep 24


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