VEGF expression in human brain tissue after acute ischemic stroke

Ischemic stroke is the third most common cause of death in humans, requiring further studies to elucidate its pathophysiological background. One potential mechanism to increase oxygen delivery to the affected tissue is induction of angiogenesis. The most potent proangiogenic factor is VEGF. For this reason, our study investigated immunohistochemically VEGF reactivity in different cellular brain compartments from 15 ischemic stroke patients, as well as from 2 age control cases. By enzymatic immunohistochemistry, we investigate VEGF expression in different brain cell compartments and then we quantified its signal intensity by assessing integrated optical densities (IOD). To establish the exact cellular brain topography of VEGF immunoreactivity we performed double fluorescent immunohistochemistry series (VEGF÷NeuN, GFAP, CD68, CD105). In control samples, VEGF reactivity was observed especially in neurons from the Brodmann cortical layers IV to VI and in protoplasmic astrocytes from the deeper layers of gray matter and in endothelial cells from normal blood vessels because of systemic hypoxia generated after death. In acute ischemic stroke samples, this reactivity was noticed in all brain cellular compartments but with different intensities. The most reactive compartment was the neurons, the intensity of VEGF reaction decreasing with the lesional age from the core infarct toward intact adjacent brain cortex. With a lower intensity, VEGF reaction was noticed in astrocytes compartments, especially in gemistocytic astrocytes adjacent to the liquefaction zone. We also noticed a weak reaction in activated non-phagocytic microglia from the periphery of liquefaction zones, and high VEGF-CD105 colocalization values at the level of microvessels that surround the infarcted brain area. In conclusion, this reactivity could suggest that VEGF might exhibit neuronal and glial protective effects and also a neoangiogenic property in acute ischemic stroke, facts that may have significant therapeutically impact on these patients.     

Complications of hydroxyethyl starch in acute ischemic stroke and other brain injuries

Serious complications of hydroxyethyl starch (HES) administration have been repeatedly demonstrated in clinical trials of acute ischemic stroke and other brain injuries. Such complications have prompted the premature termination of several randomized trials. Coagulopathy and bleeding have been the most frequently documented complications in the brain injury setting and have occurred after exposure to HES solutions of widely varying molecular weight and substitutions. Severe, protracted, refractory pruritus is another HES complication. Claims of safety for HES solutions have often been made on the basis of small trials with inadequate statistical power. Additionally, the safety has been typically assessed in highly selected low-risk patient populations receiving relatively small HES doses, so that the results cannot be generalized to routine clinical practice. The preponderance of available evidence suggests that HES solutions should be avoided in acute ischemic stroke and other brain injuries.     

急性缺血性脑卒中大鼠脑组织中Th17/Treg的变化

目的:免疫炎症反应在急性缺血性脑卒中的病理生理过程中发挥着重要的作用。具有促炎作用的辅助性T细胞17(Th17)及维持免疫耐受的调节性T细胞(Treg)是体内重要的2种免疫细胞。Th17/Treg细胞平衡是机体维持正常免疫的基础。本研究探讨急性缺血性脑卒中大鼠脑组织中Th17/Treg的变化。方法:采用线栓法制备SD大鼠急性大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)模型,以假手术组作为对照组。在MCAO术后3 d利用TTC染色观察各组大鼠脑梗死体积;采用ELISA测定脑组织中白细胞介素17A(IL-17A)和IL-10蛋白的含量;采用RT-qPCR测定脑组织中IL-17、IL-10、Foxp3和RORγt的mRNA表达水平;采用流式细胞术测定脑组织中Th17细胞和Treg细胞的比例变化。结果:与假手术组相比,MCAO组大鼠脑组织中IL-17A的含量增加,IL-10的含量减少(P0.05);RORγt和IL-17的mRNA表达水平上调(P0.05),Foxp3和IL-10的mRNA表达水平下调(P0.05);脑组织Th17细胞增多,Treg细胞明显减少(P0.05),Th17/Treg比值升高(P0.05)。结论:急性缺血性脑卒中大鼠脑组织Th17细胞增多,Treg细胞减少,表明脑梗死后大鼠脑组织中Th17/Treg的平衡被破坏,免疫炎症反应被激活。     

Delineation of the ischemic stroke lesion based on watershed and relative fuzzy connectedness in brain MRI

Precise segmentation of stroke lesions from brain magnetic resonance (MR) images poses a challenging task in automated diagnosis. In this paper, we proposed a new method called watershed-based lesion segmentation algorithm (WLSA), which is a novel intensity-based segmentation technique used to delineate infarct lesion in diffusion-weighted imaging (DWI) MR images of the brain. The algorithm was tested on a series of 142 real-time images collected from different stroke patients reported at IMS and SUM Hospital. One MRI slice having largest area of infract lesion is selected from each patient from multiple slices. The main objective is to combine the strength of guided filter and watershed transform through relative fuzzy connectedness (RFC) to detect lesion boundaries appropriately. The extracted informative statistical and geometrical features are used to classify the types of stroke lesions according to the Oxfordshire Community Stroke Project (OCSP) classification. The experimental results demonstrated the effectiveness of the proposed process with high accuracy in delineating lesions. A classification with a dice similarity index (DSI) of 96% with computational time of 0.06 s in random forest (RF) and an accuracy of 85% with computational time of 0.84 s has been obtained by multilayer perceptron (MLP) neural network classifier in tenfold cross-validation process. Better detection accuracy is achieved in RF classifier in classifying stroke lesions.     

Quantitative prediction of ischemic stroke tissue fate

Accurate prediction of ischemic tissue fate could aid clinical decision-making in the treatment of acute stroke. We investigated predictions of tissue fate for three (30-min, 60-min and permanent) stroke models in rats. Quantitative cerebral blood flow (CBF), apparent diffusion coefficient (ADC) and spin-spin relaxation time constant (T(2)) were acquired during the acute phase and at the end point followed by histological examination. Probability-of-infarct profiles based on ADC and CBF data were constructed using a training dataset. Probability-of-infarct maps were predicted using only acute stroke data from a separate experimental dataset, revealing the likelihood of future infarction. Performance measures of sensitivity and specificity showed accurate predictions. Sensitivities (mean +/- SD) for the 30-min, 60-min and permanent stroke were, respectively, 82 +/- 6%, 82 +/- 7%, and 86 +/- 4%, specificities were 83 +/- 5%, 86 +/- 5%, and 89 +/- 6%, and the areas under the receiver operating curve were 87 +/- 3%, 90 +/- 4%, and 93 +/- 3%. Importantly, to improve prediction accuracy, we took into account regional susceptibility to infarction. Spatial frequency-of-infarct maps were constructed and predictions were made by taking the weighted average of the probability-of-infarct map and spatial frequency-of-infarct map. The optimal weighting coefficient of spatial frequency-of-infarct was small (10%) for the permanent occlusion group but surprisingly large (40%) for the reperfusion groups, indicating that regional susceptibility of infarction was important for accurate prediction in reperfusion stroke. We concluded that the likelihood of cerebral infarction in rats can be accurately predicted and that accounting for regional susceptibility of infarct further improves prediction accuracy. Predictive models have the potential to provide a valuable quantitative framework for clinicians to consider different stroke treatment options. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Expression of cyclin-dependent kinase 5 mRNA and protein in the human brain following acute ischemic stroke

Neuronal cell death after brain ischemia may be regulated by activation of cyclin-dependent kinase 5 (Cdk5). In this study, expression of Cdk5 and its activator p35/p25 was examined in human post-mortem stroke tissue and in human cerebral cortical fetal neurons and human brain microvascular endothelial cells exposed to oxygen-glucose deficiency and reperfusion. The majority of patients demonstrated increased expression of Cdk5 and p-Cdk5 in stroke-affected tissue, with about a third showing increased p35 and p25 cleaved fragment as determined by Western blotting. An increase in Cdk5-, p-Cdk5- and p35-positive neurons and microvessels occurred in stroke-affected regions of patients. Staining of neurons became irregular and clumped in the cytoplasm, and nuclear translocation occurred, with colocalization of p35 and Cdk5. Association of Cdk5 with nuclear damage was demonstrated by coexpression of nuclear Cdk5 in TUNEL-positive neurons and microvessels in peri-infarcted regions. In vitro studies showed up-regulation and/or nuclear translocation of Cdk5, p-Cdk5 and p35 in neurons and endothelial cells subjected to oxygen-glucose deficiency, and strong staining was associated with propidium iodide positive nuclei, an indicator of cellular damage. These results provide new evidence for a role of Cdk5 in the events associated with response to ischemic injury in humans.     

Expression of interleukin-17 in ischemic brain tissue

Ischemic brain injury is acute local inflammation, leading to accumulation of pro-inflammatory cytokines. Cytokines influence the recruitment of leucocytes and play a key role in the inflammatory injury processes. Recently, a number of studies have demonstrated a close relationship between brain ischemia and cytokines. Interleukin-17 (IL-17) is a newly identified T-cell-specific cytokine. In this study, we evaluated the source and the action of IL-17 over the course of cerebral ischemia in rats (Sprague-Dawley) and humans. The levels of IL-17 in the ischemic hemisphere of the human brain, which was removed at necropsy, were assayed immunohistochemically. In rats, permanent middle cerebral artery occlusion (pMCAO) was obtained by inserting nylon monofilament into the right external carotid artery, occluding the right middle cerebral artery. The expression of IL-17 mRNA in rat was assayed using oligoprobe in situ hybridization. IL-17 production by neuroglial cells was assayed by double-staining using antibody glial fibrillary acidic protein (GFAP) and antibody IL-17. Levels of IL-17 were elevated in the ischemic hemispheres of human brain compared with the opposite normal hemispheres and peaked at days 3-5 after brain ischemia. The IL-17-positive cells were found in the ischemic lesion region. IL-17 mRNA was also elevated in ischemic hemispheres of pMCAO-operated rats, which were slightly elevated after 1 h and peaked at 6 days. IL-17 and GFAP double-stained were extensive in rat ischemic hemisphere. The ischemia-induced IL-17 expression in human brain reported here for the first time was very similar to that in rat model except that the peak was slightly earlier. We found for the first time that IL-17 was involved in an intense inflammatory reaction of brain ischemic injury in human. In pMCAO-operated rats, our findings suggest that IL-17 is produced by the neuroglial cells in the brain region undergoing ischemic insult. We suggest that in additional to T cells the neuroglial cell may be another cellular origin of IL-17 in later progression of brain ischemia.     

脑组织c-fos的表达和急性高眼压诱导的视网膜缺血再灌注损伤研究进展

青光眼时眼压升高能造成视网膜缺血性损害，而在视觉传导通路中，如果一组神经元受到损害，那么在其通路远端的承担相同功能的神经元也会出现退行性改变。在这种损害过程中，c-fos的作用愈来愈受到关注。正常情况下，c-fos与细胞的生长分化繁殖密切相关。病理情况下，早期认为它的出现与神经细胞的自我修复有关，但近年的研究表明，它与脑组织继发损害的关系十分密切。     

二氢杨梅素下调大鼠缺血性脑卒中脑组织炎症小体Nod样受体蛋白3的表达

目的 研究二氢杨梅素(DHM)在大鼠缺血性脑卒中治疗方面的作用,并探讨其对炎症小体Nod样受体蛋白3(NLRP3)表达的影响.方法 取70只SD大鼠,利用线栓法构建大鼠大脑中动脉栓塞(MCAO)模型,采用Longa评分、TTC染色、Nissl染色、免疫组织化学染色及Western blotting等方法,探讨DHM对M...     

A controlled trial of nimodipine in acute ischemic stroke

Recent investigations suggest that increased cellular calcium concentrations may be implicated in neuronal death after ischemia. To determine whether treatment with a calcium-channel blocker would improve survival and neurologic outcome in acute ischemic stroke, we enrolled 186 patients in a prospective, double-blind, randomized, placebo-controlled trial of nimodipine (30 mg every six hours), begun within 24 hours of the onset of symptoms of an acute ischemic stroke. During the four-week treatment period, mortality from all causes was significantly reduced with nimodipine as compared with placebo (8 deaths [8.6 percent] vs. 19 [20.4 percent]). The improvement in survival was restricted to men. During the follow-up period of six months, an additional eight patients in each group died. A significantly better neurologic outcome, as assessed by the Mathew scale of neurologic deficit, was also observed in the nimodipine group. The improvement in neurologic status was greatest in patients with a moderate to severe deficit at base line. There were no important side effects except for one episode of reversible azotemia that may have been related to treatment with nimodipine. Our data suggest that patients with acute ischemic stroke may benefit from early treatment with nimodipine, but this therapeutic effect appears to be limited to men.     

Plasma biomarkers in the diagnosis of acute ischemic stroke

Rapid diagnosis and timely treatment improves the outcome in patients with ischemic stroke, but a rapid and sensitive blood test for ischemic stroke does not exist. This study tested whether a panel of biomarkers might be useful in the diagnosis of acute ischemic stroke. Consecutive patients with suspected stroke presenting to the emergency department of a university hospital in Korea were enrolled. Plasma specimens were assayed for brain natriuretic peptide, D-dimer, matrix metalloproteinase-9, S100β, and a proprietary composite multimarker index (MMX). There were 139 patients in this study, 89 of whom were diagnosed with acute ischemic stroke, 11 with acute cerebral hemorrhage, and 39 with other brain disorders. The MMX value was significantly higher in the patients with acute ischemic stroke in comparison to 57 healthy controls (p <0.001), but there was no significant difference between the MMX value in patients with acute ischemic stroke vs those with acute cerebral hemorrhage (p = 0.884). The discriminatory capacity of MMX was modest, with an area under the receiver-operating-characteristic curve of 0.714 for acute stroke. Ischemic stroke was not diagnosed by any of the biochemical markers individually. Although the data suggest that MMX may be helpful to diagnose an acute stroke, it does not discriminate between acute ischemic stroke and acute hemorrhagic stroke.