大鼠局灶性脑缺血后神经营养因子表达的自然变化

目的 观察大鼠局灶性脑缺血后大鼠神经行为、梗死体积、组织形态及缺血半暗带神经生长因子(NGF)、脑源性神经营养因子(BDNF)的表达水平变化。方法 将健康雄性SD大鼠24只随机分为2组,Ⅰ组(假手术组); Ⅱ组(脑缺血组)。用线栓法建立动物模型,不给予再灌注,各组在术后48h断头取脑,处死前行神经功能评分,用氯化三苯基四氮唑(TTC)染色计算脑梗死体积,用HE染色观察组织学形态,用免疫组织化学染色观察NGF、BDNF的表达水平。结果 Ⅰ组在神经功能评分、梗死体积、组织形态及大脑皮层相应部位NGF、BDNF阳性细胞数均正常。与Ⅰ组比较,Ⅱ组的神经功能评分和梗死体积均严重受损; 光镜下Ⅱ组缺血性病理改变较重,与Ⅰ组比较,Ⅱ组缺血半暗带NGF、BDNF阳性神经元数增加(P<0.05)。结论 脑缺血本身可上调缺血半暗带NGF、BDNF的表达水平。     

动脉栓塞法复制局灶性脑缺血模型的影响因素探讨

目的　提高栓塞法大鼠局灶性脑缺血 (MCAO)模型的成功率和稳定性 ,探讨大鼠体重、栓子体积、插管深度与MCAO模型成功的关系。方法　采用 2× 2× 2析因设计 ,通过检测神经功能缺损评分和脑梗死体积进行分析。结果　栓子体积、插管深度的两水平之间有显著性差异 (P <0 .0 1) ,大鼠体重两水平之间无差异 (P >0 .0 5 ) ;栓子体积和插管深度之间有显著性交互作用 (P <0 .0 5 ) ,其余两两因素之间以及三者之间无交互作用 (P >0 .0 5 )。结论　最佳造模方案是大鼠体重 2 80～ 30 0g、动脉血栓子≈ 1.0 μl、导管插入颈内动脉入口 1.5cm ,该方案制作的MCAO模型成功率高 ,梗死面积稳定 ,重复性好。导管进入大脑中动脉的深度是模型成功的关键。     

Magnetic resonance spectroscopy in cerebral ischemia.

Magnetic resonance spectroscopy (MRS) has been a fundamental and invaluable tool in the fields of chemistry and physics for over 40 years and has only been applied directly to the field of medicine in the last decade. MRS has contributed significant information on ischemic brain metabolism in the clinical patient. The potential of spectroscopy now extends to the diagnostic monitoring of metabolic change, in identifying markers of a therapeutic window, and establishing prognosis and outcome. This article presents a review of MRS studies of cerebral ischemia in clinical patients.     

Programmed cell death in cerebral ischemia.

Programmed cell death (PCD) is an ordered and tightly controlled set of changes in gene expression and protein activity that results in neuronal cell death during brain development. This article reviews the molecular pathways by which PCD is executed in mammalian cells and the potential relation of these pathways to pathologic neuronal cell death. Whereas the classical patterns of apoptotic morphologic change often do not appear in the brain after ischemia, there is emerging biochemical and pharmacologic evidence suggesting a role for PCD in ischemic brain injury. The most convincing evidence for the induction of PCD after ischemia includes the altered expression and activity in the ischemic brain of deduced key death-regulatory genes. Furthermore, studies have shown that alterations in the activity of these gene products by peptide inhibitors, viral vector-mediated gene transfer, antisense oligonucleotides, or transgenic mouse techniques determine, at least in part, whether ischemic neurons live or die after stroke. These studies provide strong support for the hypothesis that PCD contributes to neuronal cell death caused by ischemic injury. However, many questions remain regarding the precise pathways that initiate, sense, and transmit cell death signals in ischemic neurons and the molecular mechanisms by which neuronal cell death is executed at different stages of ischemic injury. Elucidation of these pathways and mechanisms may lead to the development of novel therapeutic strategies for brain injury after stroke and related neurologic disorders.     

Thrombolysis in cerebral ischemia. An overview

Thrombolytic therapy for acute ischemic stroke within the 3-h time window has been approved. In the US, where FDA approval has existed for about 4 years, less than 2% of stroke patients presently receive thrombolytic therapy. This review illustrates all completed trials of intravenous and intra-arterial thrombolytic therapy for carotid artery and vertebrobasilar artery stroke and includes recommendations for therapy, diagnostic procedures and their effect on patient selection, meta-analyses, phase IV trials, and cost efficacy analyses.     

Serum markers of cerebral ischemia.

Rapid diagnosis and management of stroke patients is becoming increasingly important with the emergence of new interventional strategies for acute cerebral ischemia. A biochemical surrogate of cerebral ischemia, rapidly detectable in the serum before radiological diagnosis, might have clinical utility in the setting of acute stroke, high-risk cardiovascular procedures, and subarachnoid hemorrhage. Such a marker might also aid in the neurological prognosis of anoxic brain injury. Several serum markers have been evaluated in acute cerebral ischemia. These include neuronal enzymes such as neuron-specific enolase; markers of glial injury and activation, such as protein S100beta; and mediators of inflammation, such as interleukin-6. The clinical and preclinical data supporting the use of these biochemical surrogates of cerebral ischemia are reviewed.     

影像学存在缺血性脑血管病变患者痴呆发生率及相关影响因素分析

目的 影像学检查发现许多中老年人无论是否发生脑梗死,都存在缺血性脑血管病相关影像学改变,本研究旨在探讨在特定影像学条件下,血管性痴呆(vascular dementia,VaD)发生率及相关影响因素分析.方法 以影像学存在缺血性脑血管病病变的患者或轻型脑梗死患者作为研究对象,MRI影像学检查,表现为新发脑梗死、陈旧性脑梗死、多发腔隙性脑梗死、脑白质病变、脑萎缩等病灶,发病后7d内进行MMSE认知检测,分为VaD组和非痴呆组,对比两组一般资料、影像学表现、既往疾病、生活方式及跌倒评分、ADL评分等情况,探讨MRI影像学存在脑缺血病灶的患者及发生脑梗死的患者中,VaD发生率及相关影响因素.结果 选取的460例患者符合影像学表现.临床表现为脑梗死局灶症状、短暂性脑缺血发作、头晕、头痛、反应迟钝等症状,与非VaD组相比,VaD组患者在性别、年龄、NIHSS评分、跌倒评分、ADL评分、累积脑梗死发病及影像学伴有脑白质病变和/或脑萎缩方面与非痴呆组均有差异(P＜0.05);两组在TOAST分型、病灶部位和范围、吸烟、饮酒、高血压、糖尿病、冠心病、跌倒病史等方面无差异.Logistic多因素分析,男性、跌倒评分、ADL评分、影像学为脑白质病变和/或脑萎缩的表现与VaD的发生密切相关.结论 存在脑梗死、多发性腔隙性脑梗死、脑白质病变、脑萎缩的影像学条件下,无论是否发生脑梗死,均有较高的痴呆发生风险;男性、跌倒评分、ADL评分、影像学表现脑白质病变和/或脑萎缩可以预示VaD发生的风险.     

Growth factors improve neurogenesis and outcome after focal cerebral ischemia

Stem cells have been proposed as a new form of cell-based therapy in a variety of disorders, including acute and degenerative brain diseases. Endogenous neural stem cells (eNSC) reside in the subventricular zone and in the subgranular zone of the hippocampus. eNSC are capable of self-renewal and differentiation into functional glia and neurons. Unfortunately, spontaneous brain regeneration is inefficient for clinically significant improvement following brain injury. However, eNSC responses may be augmented considerably by perturbing the pathways governing cell proliferation, migration and differentiation by application of exogenous growth factors. Importantly, current evidence suggests that such perturbations may lead to better functional outcome after stroke. This article summarizes the progress made in this field.     

Sleep-waking cycle in rabbits after cerebral ischemia.

In rabbits experimental cerebral ischemia of 4-6 min was followed by degradation of the electroencephalographic sleep-waking cycle, as determined from 3 h afternoon records: I. Hyposomnia i.e., reduction of slow wave and paradoxical sleep lasting for about 2 days, was seen, with gradual normalization in case of survival. II. In the first postischemic days abundant 14-17 c/sec spindles appeared in the motor cortex against a low voltage desynchronized background, making the EEG of waking qualitatively different from control records. The results are discussed with reference to polygraphic studies in comatose patients, EEG phenomenology of drowsiness, and cerebral monoamines.     

Magnetoencephalography of focal cerebral ischemia in rats.

BACKGROUND AND PURPOSE: The purpose of this study was to use magnetoencephalography to record magnetic field changes in the brain during middle cerebral artery occlusion. METHODS: A direct-current electrocorticogram (two channels) and a direct-current magnetoencephalogram (seven channels) were simultaneously recorded from five rats subjected to middle cerebral artery occlusion for 1-2 hours. RESULTS: Direct-current electrocorticographic and direct-current magnetoencephalographic signal deflections were observed after the onset of middle cerebral artery occlusion and occurred repeatedly throughout the ischemic period, with a mean +/- SD time interval of 12 +/- 5 minutes. A one-to-one correspondence of the electrocorticographic and magnetoencephalographic signal deflections was demonstrated. CONCLUSIONS: Direct-current magnetoencephalography can provide a new noninvasive technique for studying depolarization and/or spreading depression in focal cerebral ischemia.     

Advances in cerebral ischemia: experimental approaches.

Drugs that dissolve clots, such as streptokinase and rTPA, and drugs that promote vasodilation are undergoing clinical testing for the treatment of hyperacute stroke, but an adjuvant therapy that either prolongs temporal thresholds before irreversible injury occurs or actually protects the brain from ischemia would transform these trials. Mild hypothermia, either intraischemically or at the onset of reperfusion, provides us with a gold standard for cytoprotection against which new pharmacologic strategies can be measured. The cytoprotective effects of the voltage-sensitive calcium channel blockers and the NMDA antagonists have been relatively less compelling than more recent findings with non-NMDA or AMPA antagonists. Their ability to inhibit SINN or reduce neocortical infarction is remarkable. Future randomized clinical trials for both resuscitated cardiac arrest victims and patients sustaining embolic stroke are predicted by this major advance in the field of stroke medicine.     

Anticoagulation in cerebral ischemia

Anticoagulation clearly benefits patients at risk of stroke from cerebral embolism. Conversely, patients with completed ischemic stroke are not benefited, and may show a higher mortality and morbidity because of hemorrhagic complications. Technical advances in the early, accurate diagnosis of cerebral hemorrhage, the constant infusion of heparin, and closer monitoring of anticoagulation have continued to reduce the risk of hemorrhage in treated patients. In patients with TIA, alternative therapy with anti-platelet agents, which appears to prevent stroke at less bleeding risk, is under study. Current results show no differences between the two therapies, but only historical controls are available for evaluation of benefit. Whether or not anticoagulation prevents progression of neurologic deficit in patients with strokes-in-evolution remains an unanswered question, which can be resolved only by prospective, randomized, controlled trials.     

Polyamines in cerebral ischemia

The present series of experiments was designed to study regional profiles of polyamines (putrescine, spermidine, and spermine) in reversible cerebral ischemia produced in rats and Mongolian gerbils. Polyamine profiles did not change during ischemia, but did following recirculation. The most prominent changes were a dramatic postischemic increase in putrescine and a marked decrease in spermine in severely damaged regions. Within a given brain structure, the postischemic putrescine levels correlated closely with the density of ischemic cell injury and the time period of cerebral ischemia. Furthermore, putrescine was already considerably increased in the CA1-subfield of the hippocampus of gerbils after 8 h recirculation, i.e., at a time when the cells are still intact. The results indicate that putrescine may be viewed as an excellent biochemical correlate of ischemic cell injury. The postischemic changes in putrescine levels are discussed in relation to the known activities of this compound.     

Distribution, severity and risk factors for aortic atherosclerosis in cerebral ischemia

Significant thoracic aortic plaques (>4 mm) are an independent risk factor for ischemic stroke. Within 1 week of stroke/transient ischemic attack (TIA) onset, 105 consecutive patients underwent transesophageal echocardiography assessment of aortic plaque thickness using the criteria of Amarenco et al. (N Engl J Med 1994;331:1474-1479). A proximo-distal gradient was found in the distribution of aortic atheroma >4 mm (p = 0.04). Symptomatic coronary artery disease was associated with plaque in the proximal aorta (p = 0.03); extracranial carotid stenosis >70% was associated with plaque in the arch and descending aorta (p < 0.01). The severity of aortic plaque was associated with age on multivariable analysis (p = 0.0003 to p < 0.01). Only smoking showed predictive regional specificity (p = 0.03);no other risk factors were associated with aortic atheroma in any segment. In stroke/TIA patients, carotid stenosis >70% predicts aortic arch atheroma plaques >4 mm which may predispose to reinfarction after endarterectomy. Atheroma of the ascending aorta is associated with ischemic heart disease, and cardiac screening should be considered in asymptomatic patients.     

Changes in neuronal apoptosis and apoptosis modulatory factors in cerebral ischemia/reperfusion

BACKGROUND: The high concentration of glutamate release is the main cause for neuronal cell death. The relationship between glutamate level and apoptosis during ischemia/reperfusion injury is still unclear. OBJECTIVE: To observe the neuronal apoptosis at 24 and 72 hours following cerebral ischemia/reperfusion in rats, and analyze the possible influencing factors. DESIGN: A randomized controlled animal experiment. SETTING: School of Medicine, Southern Yangtze University. MATERIALS: Totally 30 male adult Sprague Dawley (SD) rats of clean grade, weighing 240–290 g, were obtained from Shanghai Experimental Animal Center, Chinese Academy of Sciences. The rats were randomly divided into sham-operated group (n=10) and model group (n=20). Each group was observed at 24 and 72 hours after ischemia/reperfusion, 5 rats at each time point in the sham-operated group, whereas 12 at 24 hours and 8 at 72 hours in the model group. Kits for determining apoptosis and Bcl-2 were bought from Wuhan Boster Biological Technology, Co., Ltd.; Kit for calcineurin from Nanjing Jiancheng Bioengineering Institute. METHODS: The experiment was carried out in the Functional Scientific Research Room of Southern Yangtze University from June to October in 2006. ① Right middle cerebral artery was occluded by inserting a thread through internal carotid artery (ICA). The surgical process for the sham-operated rats was the same as that in the model group except a nylon suture inserted the ICA. According to Longa five-degree standard, the neurological deficit evaluation of rats was evaluated after surgery, and grades 1–3 were taken as successful model establishment. The blood was recirculated by withdrawing the nylon filament under anesthesia at 2 hours after ischemia in successful rat models. ②After reperfusion, the brain tissue was quickly removed at 24 or 72 hours and the slices were obtained from optic chiasma to funnel manubrium. The changes of the number of apoptotic cells were observed using the terminal deoxynucleotidyl transferase mediated dUTP-biotin nick-end labeling method. The expressions of Bcl-2 protein were determined with immunohistochemical staining. The activity of calcineurin was determined by the inorganic phosphorus method. The content of excitatory amino acid was detected by high performance liquid chromatography. MAIN OUTCOME MEASURES: ① Glutanate content in brain tissue; ② Conditions of apoptosis; ③ Calcineurin activity in brain tissue; ④ Bcl-2 expression in brain tissue. RESULTS: Totally 30 SD rats were used, 5 died and the other 25 were involved in the analysis of results. ① Changes of apoptosis: There were 0–3 apoptotic cells in the sham-operated group. In the model group, the numbers of apoptotic cells were obviously increased at 24 and 72 hours of reperfusion (P < 0.01), and it was markedly reduced at 72 hours as compared with 24 hours (P < 0.01). ② Changes of glutanate content: The glutamate contents at 24 and 72 hours of reperfusion in the model group were obviously higher than those in the sham-operated group (P < 0.01); In the model group, it was obviously increased at 24 hours as compared with 72 hours (P < 0.01). ③ Changes of Bcl-2 protein: In the model group, the Bcl-2 protein expression had no obvious changes at 24 hours of reperfusion, and it was obviously enhanced at 72 hours, which was obviously different from that in the sham-operated group and that at 24 hours (P < 0.01). ④ Changes of calcinerin activity: In the model group, the activity of calcineurin in brain tissue had no obvious changes at 24 hours of reperfusion; The activity of calcineurin at 72 hours was obviously higher than that in the sham-operated group and that at 24 hours (P < 0.01). CONCLUSION: The brain cyto-apoptosis action at different time points following reperfusion incompletely depends on the glutamate levels, while it depends on the interaction of some apoptosis related factors, such as amino acid, calcineurin, and Bcl-2, etc.     

Diffuse cerebral ischemia in the cat: III. Neuropathological sequelae of severe ischemia.

The neuropathological consequences of sever diffuse cerebral ischemia were investigated in an animal model in which postischemic alterations of regional brain blood flow and energy metabolism had been previously characterized. Pentobarbital-anesthetized cats received either 15 or 30 minutes of ischemia produced by basilar artery and bilateral carotid artery occlusions plus mild hypotension; this was followed by 60 to 90 minutes of normotensive recirculation. The brains were perfusion-fixed for light microscopy. Both insult durations resulted in unequivocal ischemic cell change affecting neurons of the cerebral neocortex, striatum, thalamus, and hippocampus and portions of the rostral brainstem. Animals with 30 minutes of prior ischemia differed from those with 15 minutes of ischemia in showing a more apparent regional accentuation of ischemic change in the parasagittal cortical gyri--the sites of previously documented focal postischemic heterogeneities of blood flow and metabolism. In other respects, however, the overall distribution and spectrum of severity of the ischemic alterations were similar for the two insult durations. These data support the view that significant permanent neuronal injury may result from a period of cerebral ischemia as brief as 15 minutes.