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. · Feb 2011
The effect of basal vasodilation on hypercapnic and hypocapnic reactivity measured using magnetic resonance imaging.
Cerebrovascular reactivity to vasodilatory hypercapnic and vasoconstrictive hypocapnic challenges is known to be altered in several hemodynamic disorders, which is often attributable to changes in smooth muscle-mediated vascular compliance. Recently, attenuated reactivity to hypercapnia but enhanced reactivity to hypocapnia was observed in patients with chronic stroke. We hypothesize that the latter observation could be explained by a change in the basal vascular tone. ⋯ Using blood oxygenation level-dependent functional magnetic resonance imaging at 3 T, breath holding and cued deep breathing respiratory challenges were administered to assess hypercapnia and hypocapnia reactivity, respectively. During the predilated condition, vasoconstrictive reactivity to hypocapnia was significantly (21.1%, P=0.016) enhanced throughout the gray matter, whereas there was no significant change (6.4%, P=0.459) in hypercapnic vasodilatory reactivity. This suggests that baseline vasodilation may explain the enhanced hypocapnia reactivity observed in some stroke patients, and that hypocapnia challenges may help identify the level of vascular compliance in patients with reduced cerebral perfusion pressure.
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J. Cereb. Blood Flow Metab. · Feb 2011
The cytokine response to human traumatic brain injury: temporal profiles and evidence for cerebral parenchymal production.
The role of neuroinflammation is increasingly being recognised in a diverse range of cerebral pathologies, including traumatic brain injury (TBI). We used cerebral microdialysis and paired arterial and jugular bulb plasma sampling to characterise the production of 42 cytokines after severe TBI in 12 patients over 5 days. We compared two microdialysis perfusates in six patients: central nervous system perfusion fluid and 3.5% human albumin solution (HAS); 3.5% HAS has a superior fluid recovery (95.8 versus 83.3%), a superior relative recovery in 18 of 42 cytokines (versus 8 of 42), and a qualitatively superior recovery profile. ⋯ Brain extracellular fluid concentrations were significantly higher than plasma concentrations for 19 cytokines: basic fibroblast growth factor (FGF2), G-CSF, IL1α, IL1β, IL1ra, IL3, IL6, IL8, IL10, IL12p40, IL12p70, IP10, monocyte chemotactic protein (MCP)1, MCP3, MIP1α, MIP1β, PDGF-AA, transforming growth factor (TGF)α and vascular endothelial growth factor. No clear arterio-jugular venous gradients were apparent. These data provide evidence for the cerebral production of these cytokines and show a stereotyped temporal pattern after TBI.
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J. Cereb. Blood Flow Metab. · Feb 2011
Outcome-related metabolomic patterns from 1H/31P NMR after mild hypothermia treatments of oxygen-glucose deprivation in a neonatal brain slice model of asphyxia.
Human clinical trials using 72 hours of mild hypothermia (32°C-34°C) after neonatal asphyxia have found substantially improved neurologic outcomes. As temperature changes differently modulate numerous metabolite fluxes and concentrations, we hypothesized that (1)H/(31)P nuclear magnetic resonance (NMR) spectroscopy of intracellular metabolites can distinguish different insults, treatments, and recovery stages. Three groups of superfused neonatal rat brain slices underwent 45 minutes oxygen-glucose deprivation (OGD) and then were: treated for 3 hours with mild hypothermia (32°C) that began with OGD, or similarly treated with hypothermia after a 15-minute delay, or not treated (normothermic control group, 37°C). ⋯ Cell death was decreased by immediate hypothermia, but was equally substantially greater with normothermia and delayed hypothermia. Potentially important biomarkers in the (1)H spectra included PCr-(1)H (phosphocreatine in the (1)H spectrum), ATP-(1)H (adenosine triphosphate in the (1)H spectrum), and ADP-(1)H (adenosine diphosphate in the (1)H spectrum). The findings suggest a potential role for metabolomic monitoring during therapeutic hypothermia.