Search results for "Penumbra"
showing 10 items of 13 documents
MitoKATP-channel opener protects against neuronal death in rat venous ischemia.
2005
OBJECTIVE: Mitochondrial adenosine triphosphate-dependent potassium (mitoK ATP ) channels are present in the brain, and several reports have shown their neuroprotective, preconditioning effect against an ischemic insult. The role of mitoK ATP channels in the penumbra area has not been studied thoroughly. In a model of venous ischemia, widespread penumbra-like low flow areas are created, which are susceptible to cortical spreading depression. Thus, we studied effects of mitoK ATP channels on infarct size in this model. METHODS: Male Wistar rats were subjected to two-vein occlusion by photochemical thrombosis of two adjacent cortical veins combined with KCI-induced cortical spreading depressi…
Faim2 contributes to neuroprotection by erythropoietin in transient brain ischemia.
2018
Delayed cell death in the penumbra region of acute ischemic stroke occurs through apoptotic mechanisms, making it amenable to therapeutic interventions. Fas/CD95 mediates apoptotic cell death in response to external stimuli. In mature neurons, Fas/CD95 signaling is modulated by Fas-apoptotic inhibitory molecule 2 (Faim2), which reduces cell death in animal models of stroke, meningitis, and Parkinson disease. Erythropoietin (EPO) has been studied as a therapeutic strategy in ischemic stroke. Erythropoietin stimulates the phosphatidylinositol-3 kinase/Akt (PI3K/Akt) pathway, which regulates Faim2 expression. Therefore, up-regulation of Faim2 may contribute to neuroprotection by EPO. Male Faim…
Neuroprotection and glutamate attenuation by acetylsalicylic acid in temporary but not in permanent cerebral ischemia.
2007
To assess the effects of acetylsalicylic acid (ASA) on glutamate and interleukin-6 (IL-6) release in the striatum of rats suffering from cerebral ischemia, we used the microdialysis technique with probes implanted 2 h prior to stroke onset. A total of 36 rats were randomly assigned to either temporary (90 min, n = 18) or permanent (n = 18) middle cerebral artery occlusion (MCAO). Animals received either a bolus of 40 mg/kg ASA or saline as control 30 min after stroke onset. Permanent MCAO led to large infarct volumes with no differences between treatment with ASA (239.8 ± 4.1 mm3) and saline (230.1 ± 3.9 mm3, p = 0.15). In contrast, ASA therapy in temporary ischemia (87.2 ± 6.2 mm3) reduced…
Effects of Cortical Spreading Depression on Cortical Blood Flow, Impedance, DC Potential, and Infarct Size in a Rat Venous Infarct Model
2000
A cortical venous infarction model has been evaluated as to the degree of regional flow reduction and by studying effects of cortical spreading depression (CSD). Two adjacent cortical veins were occluded photochemically with rose bengal and fiberoptic illumination. Seven rats served to demonstrate effects on regional cortical blood flow using laser Doppler scanning. In 36 rats local CBF, DC potential, and brain tissue impedance were measured continuously for 75 min after vein occlusion. No, 3, or 10 CSD waves were induced by potassium chloride injection during the initial 75 min. Rats were compared for spontaneous CSDs; baseline local CBF, CBF, and impedance response to CSD; and infarct vol…
Penumbral oscillations in Na D lines
1990
Penumbral oscillations were measured in two opposite parts in the penumbra of a spot, using photographic spectra of Na D lines. Power spectra of velocities show the presence of the 5-min oscillation with lowv rms. Coherence and phase analyses between the velocity fluctuations of the lines are also studied. The results seem to show that the 5-min oscillation is still surviving as a standing or evanescent wave at the height of formation of Na D lines.
Spreading Depression Induces Permanent Cell Swelling Under Penumbra Conditions
2000
Background. Spreading depression (SD) is known to go along with temporary breakdown of ion gradients and cell swelling which spontaneously normalizes. Here, the effects of SD at reduced flow conditions as encountered in the ischemic penumbra are examined.
Endothelial Cell Swelling and Brain Perfusion
1997
Background: Whereas the contribution of glial swelling to no-reflow conditions in the ischemic penumbra or during reperfusion after global ischemia is widely discussed, little is known about cell volume control of endothelial cells under reperfusion conditions. Methods: The effect of extracellular acidosis-a key mediator of secondary brain damage-on cell volume was studied in the GM7373 endothelial cell line. Experiments were performed at pH = 6.0 in the presence or absence of bicarbonate, and during exposure to inhibitors of specific transport systems such as ethyl isopropyl amiloride or 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. Results: Endothelial swelling to 111.1 ± 3.4% was f…
Temporal changes in free iron levels after brain ischemia
2008
Whereas iron chelators have been proposed as therapeutic agents in stroke, changes in free iron levels have never been explored after focal brain ischemia. Therefore, free and total iron levels in cortical tissue and free iron levels in plasma were measured before and after (1, 4 and 24h) photothrombotic occlusion of cortical vessels in rats. Brain ferritin expression and localization were also investigated before and after (24, 72 and 192 h) occlusion. The results showed that free iron remained below detectable levels in plasma and that the lesion exhibited high levels of free and total iron. As compared to contralateral values, free iron levels in ischemic core and penumbra increased (+50…
Temporal profile of gene induction after venous ischemia accompanied by spreading depression as compared to spreading depression alone
2002
Abstract The occlusion of two adjacent cortical veins is followed by a widespread reduction of rCBF and the occurrence of small infarcts, which become larger if spreading depression (SD) occurs. The model appears to be useful for studying penumbra pathophysiology. Here, the time course of gene expression in the penumbra was compared to those induced by the SD alone. In an experiment involving rats, an occlusion of two cortical veins was induced by i.v. rose bengal and fiberoptic illumination. Ten SDs were induced at 7-min intervals. Changes of the gene expression after 2, 8, 24 and 72 h were analysed for 13 genes by RT-PCR. The housekeeping gene glyceraldehyde-3-phosphate dehydrogenase (GAP…
Temporal Profile of Gene Induction After Venous Ischemia and Effects of Spreading Depression
2004
Occlusion of two adjacent cortical veins is followed by a widespread reduction of rCBF and the occurrence of small infarcts, which become larger if spreading depression (SD) occurs. The infarct matures over time with TUNEL-positive cells seen in the penumbra up to 4 days after vein occlusion. Caspase inhibition with zVAD.fmk reduces infarct size. Here, the time course of gene expression in the penumbra is compared to that induced by SD alone.