Stroke; a journal of cerebral circulation
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We evaluated the utility of blood flow velocity measurements by transcranial Doppler ultrasonography as a tool to indirectly measure cerebral perfusion during cardiopulmonary bypass. ⋯ We can monitor cerebral perfusion and metabolism by measurements of relative velocity and modified cerebral metabolic rate for oxygen during hypothermic cardiopulmonary bypass.
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We previously reported that L-arginine infusion increased pial vessel diameter by nitric oxide-dependent mechanisms, improved regional cerebral blood flow (rCBF) distal to middle cerebral artery (MCA) occlusion, and reduced infarction volume in spontaneously hypertensive rats when administered intraperitoneally before and after MCA occlusion. In this report we extend our findings (1) by examining the time course of L-arginine on rCBF and pial vessel diameter under basal conditions and on rCBF after MCA occlusion and (2) by reproducing the protective effect of L-arginine on infarct volume when given intravenously immediately after the onset of MCA occlusion in both normotensive and hypertensive models of focal cerebral ischemia. ⋯ These studies extend our previous findings by demonstrating that exogenous L-arginine induces sustained rCBF increases in normal brain as well as in a marginally perfused brain region distal to MCA occlusion. Our data in Sprague-Dawley rats support the conclusion that L-arginine-induced increases in rCBF can decrease infarction volume. We conclude that nitric oxide-mediated mechanisms increase rCBF and decrease infarction volume after MCA occlusion in both normotensive and hypertensive animals.
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This study investigated whether the nitric oxide synthase inhibitor NG-nitro-L-arginine-methyl ester (L-NAME) would alter blood flow and oxygen balance in the ischemic cerebrocortex of isoflurane-anesthetized Long-Evans rats. ⋯ These observations suggest that despite a decrease in cerebral blood flow, inhibition of nitric oxide synthesis mildly improves the oxygen supply and consumption balance in the ischemic cortex.
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We sought to examine the effect of moderate hypothermia (30 degrees C to 32 degrees C) initiated after resuscitation on the scavenging systems of free radicals and lipid peroxidation in canine brain tissue after cardiac arrest and resuscitation. ⋯ Moderate hypothermia initiated after resuscitation can significantly inhibit the accumulation of lipid peroxidation products and the consumption of free radical scavengers in the brain tissue.
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Aspects of the mechanisms of hemostasis are reviewed with particular emphasis on the assembly of enzyme complexes on the membranes of cells. The way this membrane fixation of reactions accelerates coagulation, inhibition, and fibrinolytic systems is discussed. The complex nature of the hemostatic system and the multiple complications of its abnormalities present a difficult problem for the neurologist and neurosurgeon managing the patient with intracerebral hemorrhage. This is a situation in which close consultation and collaboration among the neurological and hematologic specialists are imperative to achieve the most favorable outcome for the patient with this life-threatening situation.