Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism
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J. Cereb. Blood Flow Metab. · Jun 2009
Post-ischemic helium provides neuroprotection in rats subjected to middle cerebral artery occlusion-induced ischemia by producing hypothermia.
During the past decade, studies on the manipulation of various inhaled inert gases during ischemia and/or reperfusion have led to the conclusion that inert gases may be promising agents for treating acute ischemic stroke and perinatal hypoxia-ischemia insults. Although there is a general consensus that among these gases xenon is a golden standard, the possible widespread clinical use of xenon experiences major obstacles, namely its availability and cost of production. ⋯ We have investigated whether helium provides neuroprotection in rats subjected to middle cerebral artery occlusion (MCAO) when administered after reperfusion, a condition prerequisite for the therapeutic viability and possible clinical use of helium. In this study, we show that helium at 75 vol% produces neuroprotection and improvement of neurologic outcome in rats subjected to transient MCAO by producing hypothermia on account of its high specific heat as compared with air.
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J. Cereb. Blood Flow Metab. · Jun 2009
Neuroinflammation extends brain tissue at risk to vital peri-infarct tissue: a double tracer [11C]PK11195- and [18F]FDG-PET study.
Focal cerebral ischemia elicits strong inflammatory responses involving activation of resident microglia and recruitment of monocytes/macrophages. These cells express peripheral benzodiazepine receptors (PBRs) and can be visualized by positron emission tomography (PET) using [(11)C]PK11195 that selectively binds to PBRs. Earlier research suggests that transient ischemia in rats induces increased [(11)C]PK11195 binding within the infarct core. ⋯ Contrasting with earlier data for transient ischemia, no [(11)C]PK11195 binding was found in the infarct core. Rather, permanent ischemia caused increased [(11)C]PK11195 binding in the normoperfused peri-infarct zone (mean standard uptake value (SUV): 1.93+/-0.49), colocalizing with a 60% increase in the [(18)F]FDG metabolic rate constant with accumulated activated microglia and macrophages. These results suggest that after permanent focal ischemia, neuroinflammation occurring in the normoperfused peri-infarct zone goes along with increased energy demand, therefore extending the tissue at risk to areas adjacent to the infarct.
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J. Cereb. Blood Flow Metab. · Jun 2009
A phase-contrast MRI study of physiologic cerebral venous flow.
Although crucial in regulating intracranial hydrodynamics, the cerebral venous system has been rarely studied because of its structural complexity and individual variations. The purpose of our study was to evaluate the organization of cerebral venous system in healthy adults. Phase-contrast magnetic resonance imaging (PC-MRI) was performed in 18 healthy volunteers, in the supine position. ⋯ Cerebrospinal fluid aqueductal and cervical stroke volumes were 41+/-22 and 460+/-149 microL, respectively. Our results emphasize the variability of venous drainage for side dominance and jugular/epidural organization. The pulsatility of venous outflow and the role it plays in the regulation of intracranial pressure require further investigation.