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Query: UMLS:C0022116 (ischemia)
 91,303 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rats and gerbils have been used widely to investigate the molecular mechanism of selective neuronal death following transient global ischemia. Recently, the availability of transgenic mice has enabled us to examine the involvement of specific gene products in various pathophysiological conditions. However, there has been only limited information about the experimental model of cerebral ischemia in mice, particularly in regard to selective neuronal death. We examined whether bilateral carotid occlusion produced global forebrain ischemia in seven common mouse strains including C57BL/6, ICR, BALB/c, C3H, CBA, ddY and DBA/2, based on neurological signs, histological findings and cortical microcirculatory as well as India ink perfusion patterns. The C57BL/6 strain was found to be the most susceptible among seven strains. All C57BL/6 mice died within 6 h after permanent bilateral carotid occlusion. After transient bilateral carotid occlusion for 20 min, more than 90% of C57BL/6 mice showed typical neurological signs such as torsion of the neck and rolling fits, and developed selective neuronal death in the hippocampus and caudoputamen. Hypothermia prevented the neuronal death. Visualization of brain vasculature by India ink perfusion indicated that the susceptibility of the mice after bilateral carotid occlusion depended mainly on the degree of anastomosis between carotid and basilar arteries. Our results showed the feasibility of investigating selective neuronal death in transgenic mice with simple temporary occlusion of both common carotid arteries, when those from the C57BL/6 strain or inbred transgenic mice from other strains with the C57BL/6 strain in a back-cross manner are used.
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PMID:C57BL/6 strain is most susceptible to cerebral ischemia following bilateral common carotid occlusion among seven mouse strains: selective neuronal death in the murine transient forebrain ischemia. 910 59

Secondary cell damage after ATP depletion due to hypoxia or ischemia is clinically important because it correlates with residual effects; post-hypoxic-ischemic fits can be associated with later cerebral palsy. The mechanisms involved in delayed secondary cell damage are not clear, possibly because extensive relevant evidence is often fragmented. However, a sequence of changes can be suggested; this cross-linked sequence is tentatively outlined in this review. The outline suggests explanations for otherwise ill-understood clinical disturbances such as the loss of inhibitory control in damaged cells and the well documented reduction of cellular ATP. Loss of control may be due to reduced synthesis of control proteins and the reduced ATP concentration may be due to increased energy consumption.
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PMID:Is post-hypoxic-ischemic cell damage associated with excessive ATP consumption rather than a failure of ATP production? 911 9

A patient who lost consciousness and had a convulsion caused by brain ischemia during balloon inflation in connection with percutaneous transluminal angioplasty was successfully treated with a continuous-perfusion dilatation catheter without complications.
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PMID:Percutaneous transluminal angioplasty of the internal carotid artery with a continuous-perfusion dilatation catheter. 912 32

Neurological symptoms in childhood miliary tuberculosis are generally caused by underlying tuberculous meningitis (TBM), since the 2 conditions commonly occur concurrently. Cerebral infarction, a well-recognized complication of TBM, usually results from tuberculous periarteritis and secondary thrombosis. Neuropathological studies have demonstrated that the anterior cerebral circulation is more commonly affected than the arteries of the vertebro-basilar system, and basilar artery occlusion as a presenting manifestation of childhood miliary tuberculosis or TBM has not been described before. We report a 13-month-old infant who presented with fever and convulsions, terminating in acute decerebration after a second prolonged seizure 1 week after the onset of symptoms. Magnetic resonance (MR) imaging demonstrated density changes compatible with acute vertebro-basilar ischemia as well as multiple cerebral granulomas. A chest radiograph showed diffuse miliary tuberculosis. Postmortem examination confirmed this diagnosis and revealed acute occlusion of the basilar artery by an infected (septic) thromboembolus showing granulomatous inflammation, which most likely arose from an endocardial vegetation with identical histology.
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PMID:Acute stroke in a child with miliary tuberculosis. 940 96

Nitric oxide (NO) is a gaseous chemical messenger which plays the role of a universal modulator of various physiological functions of animals including the nervous system, i.e., interneuronal communications, synaptic plasticity, memory formation, receptor functions, intracellular signal transmission, release of neurotransmitters. The possible role of NO is considered in some basic diseases of the central nervous system which are associated with the neurotoxic effect of glutamate (ischemia, stroke, convulsive disorders, etc.). NO is believed to be a key pathophysiological factor of these diseases. The production of NO in the brain cortex of rats was found to significantly increase during convulsions of various origin.
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PMID:Nitric oxide in mechanisms of brain damage induced by neurotoxic effect of glutamate. 972 39

Seizures are common after severe cerebral ischemia. To examine the mechanisms underlying these seizures, we determined the impact of prior forebrain ischemia on the seizure thresholds of four convulsants with differing modes of action: lidocaine, pentylenetetrazol (PTZ), N-methyl-D-aspartate (NMDA), and picrotoxin. Anesthetized Sprague-Dawley rats were chronically instrumented with screw electrodes and vascular catheters, and then subjected to 10 min of forebrain ischemia, produced by carotid occlusion and hypotension (mean arterial pressure to 30 mmHg). Animals were then awakened. 6, 24 or 48 h later, groups of awake animals received intravenous infusions of the four drugs. The total dose of drug infused prior to either electrical seizures (lidocaine, PTZ, and picrotoxin) or tonic-clonic convulsions (all drugs) were noted. For each drug, a group of Sham animals (no ischemia) served as controls. There were markedly different patterns of changes in the convulsant thresholds for the drugs. For example, at 6 h post-ischemia, rats treated with lidocaine died before convulsing, while the threshold for PTZ increased by 86%. There was no change in the picrotoxin threshold at 6 h, but the dose of NMDA needed to induce tonic-clonic seizure activity was reduced by 70%. By 48 h, lidocaine and PTZ thresholds had returned to values similar to those in Shams, but the NMDA threshold had now increased to a value 62% greater than Sham. Ten minutes of cerebral ischemia is followed by a complex and changing pattern of susceptibility to chemical convulsants. Finding suggests that early post-ischemic seizures may be related to increased NMDA receptor sensitivity.
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PMID:Forebrain ischemia: effect on pharmacologically induced seizure thresholds in the rat. 1041 92

Arachidonic acid (AA) and other nonesterified fatty acids (FAs) have been shown to exert harmful effects during cardiac ischemia. By continuously measuring intracellular pH (pH(i)) changes in neonatal and adult cardiac myocytes, we have found, for the first time, that 10 micromol/L AA induces a substantial intracellular acidosis (0.3 to 0.4 pH units). We have ruled out the possibilities that the AA-induced acidosis is caused by (1) inhibition or stimulation of the pH(i) regulators, (2) protein kinase C activation or the generation of AA metabolites or free radicals, or (3) activation of NADPH oxidase or an inward H(+) current. The AA-induced acidosis fits to a simple diffusion mechanism, as proposed by Kamp and Hamilton (flip-flop model) for artificial phospholipid bilayers. The important properties found in the cardiac myocyte are that (1) the initial rate of acid flux (J(H)) increases with the AA concentration (2 to 50 micromol/L), (2) FAs with a (-)COOH group (eg, AA, oleic acid, and linoleic acid) induce intracellular acidification, but FAs with a (-)COOCH(3) group (eg, AA methyl ester) have little effect on the pH(i), (3) tetradecylamine (FA amine) induces intracellular alkalosis, and, most importantly, (4) both the AA- and tetradecylamine-induced pH(i) changes can be reversed by 0.3% BSA. Because a low concentration of AA (10 micromol/L) can induce a substantial acidosis, the possible involvement of the FA-evoked acidosis in the negative inotropic effect during cardiac ischemia is discussed. The full text of this article is available at http://www. circresaha.org.
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PMID:Possible mechanism(s) of arachidonic acid-induced intracellular acidosis in rat cardiac myocytes. 1067 91

Hypoxia-ischemia produces brain damage by processes that continue for many hours after reoxygenation/reperfusion. This provides a window of opportunity for therapy aimed at preventing further loss of brain cells. Sulfate magnesium can prevent posthypoxic brain injury by blocking glutamate receptors within the calcium (Ca++) ion channel. We used sulfate magnesium in nine newborn infant after perinatal hypoxia. We investigated the brain damage, by ultrasound examination, on third day, in first, second and third week, and third, sixth month of life. We have estimated the neurological development in the first week of life and third and twelfth month of life. We did not find deviations in ultrasound examination. We did not observe convulsions. We did not observe any side effect of this therapy. The examination at 1 of year of life in all of children was correct.
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PMID:Can magnesium sulfate reduce the risk of cerebral injury after perinatal asphyxia? 1071 92

Preconditioning is defined as an adaptive mechanism produced by short periods of hypoxia/ischemia, resulting in protection against subsequent ischemic insult, and development of seizures. Results of the present study demonstrate that an episode of normobar hypoxia reduces the susceptibility to convulsions induced by pentylenetetrazol (PTZ) 30 min, 24 h, as well as 4 and 7 days later. Administration of morphine showed similar effects after 24 h. Naloxone, given before ischemic preconditioning, as well as morphine, blocked the development of the protection. Administration of D-Ala-Met-enkephalin-Gly-ol (DAMGO - a selective mu-opioid receptor agonist), as well as trans-3, 4-dichloro-N-methyl-N-[7-(1-pyrrolidinyl) cycloexilbenzeneacetamide ethane sulfonate] (U-69,593 - a selective kappa-opioid receptor agonist), mimicked the effects of hypoxic preconditioning (HPC). (-)-N-(Cyclopropylmethyl)-4,14-dimethoxymorphinan-6-one (cyprodime - a selective mu-opioid receptor antagonist, as well as nor-binaltorphimine dihydrochloride (nor-BNI - selective kappa-opioid receptors antagonist), given before HPC as well as before respective opioid receptor agonists, blocked the development of the protection. This study provides evidence that mu- and kappa-opioid receptors are involved in HPC against seizures in the brain.
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PMID:The role of opioid receptors in hypoxic preconditioning against seizures in brain. 1111 85

To assess the role of NMDA receptors in the modulation of a brain tolerance after a transient cerebral mild ischemia, adult mice were exposed for 30 min to bilateral clamping of the common carotid arteries (BCCA) under pentobarbital anaesthesia. The competitive NMDA antagonist CGP-40116 was administered intraperitoneally (i.p.) in two experimental paradigms: a) acute treatment: twice, 4.0 mg/kg; 1.5 hour before the clamping of vessels and 6 hours after re-circulation and b) chronic treatment in a dose of 1.0 mg/kg; started 24 hours after re-circulation and continued once daily for 13 days with the last injection 24 hours before the induction of convulsions. Seizures were evoked with bicuculline (3.5 mg/kg, i.p.) 14 days after BCCA. Transient brain oligemia induced protection against bicuculline toxicity. The acute treatment with CGP-40116 only partially diminished the anticonvulsant phenomenon. In contrast, the chronic treatment with the drug markedly potentiated the effect. It can be concluded that NMDA receptors only partially participate in the induction of a protective effect against bicuculline toxicity after BCCA. The chronic treatment with low doses of the NMDA antagonist may enhance the brain tolerance, possibly due to the chemical preconditioning.
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PMID:The influence of CGP-40116 on bicuculline evoked seizures in mice exposed to transient episode of brain oligemia. 1114 2


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