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. · Mar 2002
Increased proliferation of neural progenitor cells but reduced survival of newborn cells in the contralateral hippocampus after focal cerebral ischemia in rats.
Recent studies demonstrated that neurogenesis in the adult hippocampus increased after transient global ischemia; however, the molecular mechanism underlying increased neurogenesis after ischemia remains unclear. The finding that proliferation of progenitor cells occurred at least a week after ischemic insult suggests that the stimulus was not an ischemic insult to progenitor cells. To clarify whether focal ischemia increases the rate of neurogenesis in the remote area, the authors examined the contralateral hemisphere in rats subjected to permanent occlusion of the middle cerebral artery. ⋯ In double immunofluorescence staining, 80% of newborn cells expressed NeuN, a marker of differentiated neurons, and 10% of BrdU-positive cells expressed GFAP. However, in the other areas of the contralateral hemisphere including the rostral subventricular zone, the number of BrdU-positive cells remained unchanged. These results showed that focal ischemia stimulated the proliferation of neuronal progenitor cells, but did not support survival of newborn cells in the contralateral hippocampus.
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J. Cereb. Blood Flow Metab. · Mar 2002
Near-infrared spectroscopy cerebral oxygen saturation thresholds for hypoxia-ischemia in piglets.
Detection of cerebral hypoxia-ischemia remains problematic in neonates. Near-infrared spectroscopy, a noninvasive bedside technology has potential, although thresholds for cerebral hypoxia-ischemia have not been defined. This study determined hypoxic-ischemic thresholds for cerebral oxygen saturation (SCO2) in terms of EEG, brain ATP, and lactate concentrations, and compared these values with CBF and sagittal sinus oxygen saturation (SVO2). ⋯ The SCO2 thresholds for increased lactate, minor and major EEG change, and decreased ATP were 44 +/- 1%, 42 +/- 5%, 37 +/- 1%, and 33 +/- 1%. The SCO2 correlated linearly with SVO2 (r = 0.98) and CBF (r = 0.89), with corresponding SVO2 thresholds of 23%, 20%, 13%, and 8%, and CBF thresholds (% baseline) of 56%, 52%, 42%, and 36%. Thus, cerebral hypoxia-ischemia near-infrared spectroscopy thresholds for functional impairment are SCO2 33% to 44%, a range that is well below baseline SCO2 of 68%, suggesting a buffer between normal and dysfunction that also exists for CBF and SVO2.