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Background: Recent prospective registration studies of transient ischemic attack in Western countries demonstrated that large artery atherosclerosis is the highest risk etiology for early stroke recurrence under urgent evaluation and treatment. On the other hand, some limited transient ischemic attack studies from East Asian countries showed transient ischemic attack patients due to small vessel occlusion were at a higher early stroke risk., Aims: We aimed to assess the risk for early stroke in small vessel occlusion-transient ischemic attack patients in a Japanese large transient ischemic attack registry., Methods: We analyzed the data of a prospective Japanese transient ischemic attack registry including 1320 transient ischemic attack patients within seven days after onset. Small vessel occlusion-transient ischemic attack was defined as the presence of lacunar transient ischemic attack syndrome, without other etiologies. The outcome measure was recurrent stroke within 30 days after transient ischemic attack. The predictors of 30-day recurrent stroke were estimated using the Cox proportional hazards model., Results: The study population had a mean age of 69 ± 12 years and 470 were women. Recurrent stroke was observed in 61 patients (4.6%), and the highest rate was observed with small vessel occlusion-transient ischemic attack (7.8%), followed by large artery atherosclerosis (5.4%). In multivariate analysis, recurrent stroke was independently associated with small vessel occlusion-transient ischemic attack (hazard ratio (HR): 2.01, 95% confidence interval (CI): 1.19-3.35), higher systolic blood pressure (HR: 1.18, 95% CI: 1.08-1.28), and presentation within 3 h after onset (HR: 2.21, 95% CI: 1.27-4.04). Furthermore, small vessel occlusion-transient ischemic attack with acute small deep infarct on diffusion-weighted imaging was a stronger predictor of recurrent stroke (HR: 4.87, 95% CI: 2.09-10.0)., Conclusion: Small vessel occlusion-transient ischemic attack, especially with acute small deep infarct, had a higher early stroke risk compared with other etiologies in Japanese transient ischemic attack patients who received early management.

Aims: To investigate the relative contribution of on-treatment low-density lipoprotein (LDL) cholesterol and C-reactive protein (CRP) to the risk of recurrent stroke and transient ischemic attack (TIA) in patients with history of ischemic stroke., Methods: A total of 1095 patients with non-cardioembolic ischemic stroke were randomized into two groups: control and patients receiving 10 mg of pravastatin per day. After excluding 18 patients who did not have baseline CRP data, the effects of LDL cholesterol and CRP on recurrent stroke and TIA were prospectively assessed in 1077 patients., Results: During the follow-up of 4.9±1.4 years, there were 131 recurrent stroke or TIA cases. Patients with ontreatment LDL cholesterol ＜120 mg/dL showed 29% reduction in recurrent stroke and TIA than those with LDL cholesterol ≥ 120 mg/dL (event rate 2.20 vs. 3.11 per 100 person-years, hazard ratio [HR] 0.71, 95% confidence interval (CI) 0.50-0.99, p＝0.048). Patients with CRP ＜1 mg/L had 32% reduction compared with that of patients with CRP ≥ 1 mg/L (event rate 2.26 vs. 3.40 per 100 person-years; HR 0.68, 95% CI 0.48-0.96, p＝0.031). Although LDL cholesterol and CRP levels were not correlated in individual patients, those who achieved both LDL cholesterol ＜120 mg/dL and CRP ＜1 mg/L showed 51% reduction compared with that of patients with LDL cholesterol ≥ 120 mg/dL and CRP ≥ 1 mg/L (event rate 2.02 vs. 4.19 per 100 person-years; HR 0.49, 95% CI 0.31-0.79)., Conclusions: The control of both LDL cholesterol and CRP levels appears to be effective for preventing recurrent stroke and TIA in patients with non-cardiogenic ischemic stroke.

Background and Purpose- Patients with transient ischemic attack (TIA) occasionally show nonfocal symptoms, such as unconsciousness, amnesia, and unsteadiness. The purpose of this study was to clarify the characteristics and prognosis of patients with TIA with nonfocal symptoms, using data from the PROMISE-TIA (Prospective Multicenter Registry to Identify Subsequent Cardiovascular Events After Transient Ischemic Attack). Methods- Patients with TIA within 7 days of onset were consecutively enrolled in the Japanese nationwide registry. Factors associated with nonfocal symptoms and 1-year risks of ischemic stroke and coronary artery diseases were assessed in multivariate-adjusted models. Results- We studied 1362 patients with TIA (879 men; mean age, 69±12 years), including 219 (16%) with nonfocal symptoms. Patients with TIA with nonfocal symptoms were more likely to show acute ischemic lesions in the posterior circulation on diffusion-weighted imaging (multivariate-adjusted odds ratio, 3.07; 95% confidence interval, 1.57-5.82) and arterial stenosis or occlusion in the posterior circulation on vascular examination (odds ratio, 1.94; 95% confidence interval, 1.19-3.09) than those without nonfocal symptoms. Although 1-year risk of ischemic stroke did not differ significantly between groups (adjusted hazard ratio, 0.79; 95% confidence interval, 0.42-1.37), risk of coronary artery disease was higher in patients with TIA with nonfocal symptoms (hazard ratio, 3.37; 95% confidence interval, 1.14-9.03). Conclusions- Both acute ischemic lesions and arterial stenosis and occlusion in the posterior circulation were more frequently observed in patients with TIA with nonfocal symptoms.

Background: A transient visual symptom (TVS) is a clinical manifestation of transient ischemic attack (TIA). The aim of this study was to investigate differences in clinical characteristics among subtypes of TVS using multicenter TIA registry data., Materials and Methods: Patients with TIA visiting within 7 days of onset were prospectively enrolled from 57 hospitals between June 2011 and December 2013. Clinical characteristics were compared between patients with 3 major subtypes of TVS (transient monocular blindness [TMB], homonymous lateral hemianopia [HLH], and diplopia)., Results: Of 1365 patients, 106 (7.8%) had TVS, including 40 TMB (38%), 34 HLH (32%), 17 diplopia (16%), and 15 others/unknown (14%). Ninety-one patients with 1 of the 3 major subtypes of TVS were included. Symptoms persisted on arrival in 12 (13%) patients. Isolated TVS was significantly more common in TMB than in HLH and diplopia (88%, 62%, and 0%, respectively; P < .001). Duration of symptoms was shorter in patients with TMB than those with HLH (P = .004). The ABCD 2 score was significantly lower in patients with TMB compared with those with HLH and diplopia (median 2 [interquartile range 2-3] versus 3 [2-4] and 4 [2-5], respectively; P = .005). Symptomatic extracranial internal carotid artery stenosis or occlusion was seen in 14 (16%) patients, and was more frequent in TMB than in HLH and diplopia (28%, 9%, and 0%, respectively; P = .015)., Conclusions: TVS was an uncommon symptom in our TIA multicenter cohort. Some differences in clinical characteristics were found among subtypes of TVS., (Copyright © 2018 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: To define desirable target low-density lipoprotein (LDL) cholesterol levels for the prevention of stroke recurrence, a post hoc analysis was performed in the J-STARS study (Japan Statin Treatment Against Recurrent Stroke)., Methods: Subjects (n=1578) were divided into groups based on mean value of postrandomized LDL cholesterol levels until the last observation in 20 mg/dL increments. Adjusted hazard ratios (HRs) and 95% confidence intervals were analyzed for each group, with adjustments for baseline LDL cholesterol, baseline body mass index, hypertension, diabetes mellitus, and statin usage., Results: The postrandomized LDL cholesterol level until the last observation were 104.1±19.3 mg/dL in the pravastatin group and 126.1±20.6 mg/dL in the control group. The adjusted HRs for stroke and transient ischemic attack and all vascular events decreased in the postrandomized LDL cholesterol level of 80 to 100 mg/dL ( P =0.23 and 0.25 for the trend, respectively). The adjusted HR for atherothrombotic infarction significantly reduced with the usage of statin after adjusting baseline LDL cholesterol levels (HR, 0.39; 95% confidence intervals, 0.19-0.83). The adjusted HR for atherothrombotic infarction and intracranial hemorrhage were similar among the postrandomized LDL-cholesterol-level subgroups ( P =0.50 and 0.37 for the trend, respectively). The adjusted HR for lacunar infarction decreased in the postrandomized LDL cholesterol level of 100 to 120 mg/dL (HR, 0.45; 95% confidence intervals, 0.20-0.99; P =0.41 for the trend)., Conclusions: The composite risk of stroke and transient ischemic attack reduced in the postrandomized LDL cholesterol level of 80 to 100 mg/dL after adjusting for statin usage., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00221104., (© 2018 American Heart Association, Inc.)

Background Incidence and predictors of ischemic stroke in patients with transient ischemic attack (TIA) have not been fully clarified outside Europe and North America. Aims We undertook the present prospective, multicenter study to clarify the incidence, predictors, and etiology of ischemic stroke within one year of TIA onset in Japan. Methods The study subjects were patients within seven days of TIA onset who were enrolled in a prospective register from 57 hospitals between June 2011 and December 2013. The primary endpoint was occurrence of ischemic stroke. Results Of 1365 consecutive patients, 1245 were followed for one year after TIA onset; 101 (8.1%) experienced ischemic stroke during follow-up. The leading subtype of ischemic stroke was small-vessel occlusion (SVO) followed by large-artery atherosclerosis (LAA) attributable to intracranial artery diseases. When dividing ischemic stroke events between those occurring within the first 90 days after TIA onset and those occurring after the first 90 days, the leading subtype of ischemic stroke within the first 90 days after TIA onset was SVO, followed by LAA attributable to intracranial artery diseases. In comparison, the subtypes most commonly seen beyond the first 90 days after TIA onset were cardioembolic and LAA attributable to intracranial artery disease. The one-year risk of ischemic stroke increased significantly as ABCD 2 score increased, at 6.2% for 0-3 points, 7.2% for 4-5 points, and 11.6% for 6-7 points. Conclusions The one-year ischemic stroke risk after TIA was about 8% and was associated with the ABCD 2 score. The most common subtype of subsequent ischemic stroke was SVO.

Background: Symptoms of transient ischemic attack (TIA) persist on arrival and subsequently resolve in some patients admitted to hospitals early after onset. Differences in clinical characteristics between patients with acute TIA whose symptoms do and do not persist on arrival remain unclear., Methods: We retrospectively extracted data of consecutive TIA patients with an onset-to-door time (ODT) of 24 hours or less and without a history of stroke from a multicenter TIA database. Clinical characteristics were compared between patients with and without persisting symptoms on arrival., Results: Two hundred sixty-six patients (158 men, 68.0 ± 12.9 years) were included. Of the total number of patients, 105 (39.5%) had persisting symptoms with a mean National Institutes of Health Stroke Scale score of 2.4 (median, 1.0). Patients with persisting symptoms were more likely to have sensory disorder, ambulance-transported admission, long-duration TIA (≥60 minutes), and shorter ODT than those without. Multivariate analysis showed that sensory disorder (odds ratio [OR] 2.52, 95% confidence interval [CI] 1.35-4.77), ambulance-transported admission (OR 1.80, 95% CI 1.00-3.28), and long-duration TIA (OR 3.96, 95% CI 2.12-7.71) were positively associated and that an ODT of more than 12 hours (OR .18, 95% CI .04-.63) was inversely associated with the presence ofpersisting symptoms. Patients with persisting symptoms were more likely to be examined by a stroke physician at first (69% versus 57%, P = .049) and then hospitalized in a stroke unit (59% versus 43%, P = .010)., Conclusion: Clinical manifestations and management after admission might differ between patients with acute TIA whose symptoms do and do not persist on arrival., (Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

Background: Atrial fibrillation (AF) is an important risk factor for transient ischemic attack (TIA). However, little is known about the characteristics of TIA patients with AF. This study investigated the characteristics of such patients, using data from a retrospective, observational, multicenter study., Methods: TIA patients admitted to 13 stroke centers in Japan within 7 days of onset between January 2008 and December 2009 were included. The present analyses compared baseline characteristics, clinical symptoms, findings from diffusion-weighted imaging (DWI), and clinical outcomes between patients with and without AF (AF and non-AF groups)., Results: A total of 464 patients (292 men; mean age 68.5 ± 13.2 years) were registered. Of these, 79 patients (17%) had AF. Patients in the AF group were older (73.9 ± 9.1 vs. 67.4 ± 13.6 years, p < 0.001) and more likely to show disturbance of consciousness (13 vs. 6%, p = 0.046) and aphasia (9 vs. 3%, p = 0.007) than patients in the non-AF group. Although no difference in the overall DWI-positive rate was seen between the groups (28 vs. 20%, p = 0.102), a single lesion (23 vs. 10%, p < 0.001), a lesion ≥15 mm (11 vs. 4%, p = 0.006), and a single lesion ≥15 mm (11 vs. 2%, p < 0.001) on DWI were more frequent in the AF group. Multivariate logistic regression analysis identified increased age [odds ratio (OR) 1.04; 95% confidence interval (CI) 1.02-1.07] and DWI single lesion ≥15 mm (OR 5.67; 95% CI 1.92-16.7) as independently associated with the presence of AF., Conclusions: In this study, 17% of our TIA patients had AF. We found an association between the acute ischemic lesion pattern on DWI of a single lesion ≥15 mm and AF in TIA patients. These results might lead to a better diagnosis of TIA patients with AF.

Background: We undertook a multicenter cohort observational study to investigate the frequency and type of subsequent vascular events after an ischemic stroke and to compare the rates of vascular events between patients with and without hyperlipidemia., Methods: This nationwide study was conducted in 19 hospitals participating in the Japan Standard Stroke Registry Study. We enrolled ischemic stroke patients, including those with a transient ischemic attack, who had not experienced any vascular events before enrollment after their ischemic stroke events. Each subject was observed prospectively from September 1, 2003, to October 1, 2005, or until a primary end point or death. Primary end points included subsequent fatal or nonfatal vascular events: stroke, angina pectoris, acute myocardial infarction, aortic aneurysm, or arteriosclerosis obliterans., Results: A total of 449 patients (mean age, 67.6 years; 64.8% men) were enrolled in this study. Of the 41 vascular events observed during follow-up, 40 were stroke. The median observation period was 568 days. We found that patients with hyperlipidemia had a significantly higher rate of vascular events compared with those without hyperlipidemia according to the Kaplan-Meier method and the log-rank test (P = .013). Hyperlipidemia significantly increased the risk of vascular events (hazard ratio, 2.169 [1.125-4.312]; P = .021) according to the Cox proportional hazard model after adjusting for confounding factors (age, sex, days from ischemic stroke until enrollment, smoking habits, and daily drinking habits)., Conclusions: This study demonstrated that stroke was the most common subsequent vascular event after ischemic stroke; the study also indicated that hyperlipidemia could be a risk factor for subsequent vascular events after ischemic stroke., (Copyright © 2015 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

Background: Transient monocular blindness (TMB) is associated with a transient ischemic attack (TIA). The purpose of this study was to investigate the features of TMB in the Japanese population using data from a multicenter retrospective study of TIA., Methods: The subjects were consecutive TIA patients admitted to 13 stroke centers within 7 days after symptom onset. We compared clinical characteristics of patients with TMB and those without TMB who had other symptoms of cerebral TIA., Results: A total of 464 patients were registered between January 2008 and December 2009, and 444 patients (283 men, mean age: 68.5 years) were included in the analysis. Thirteen patients (2.9%) presented with TMB. Patients with TMB were less likely to arrive at the specialized stroke center quickly than those without TMB (P = .013). Stenotic lesions in the extracranial internal carotid artery were more common in patients with TMB (33.3% versus 9.1%, P = .022)., Conclusions: TMB was not common in our TIA inpatients. This study suggests that patients with TMB should immediately undergo a diagnostic workup, including brain and vessel imaging, and cardiac evaluation, as is performed in patients with other cerebral TIA symptoms. A larger, prospective cohort is needed to confirm the risks and outcomes of patients with TMB in the Japanese population., (Copyright © 2014 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

Background and Purpose: The aim of this study was to elucidate the factors associated with the time from symptom onset to arrival at a stroke center (onset-to-door time [ODT]) in patients with classically defined transient ischemic attack using data from a multicenter, retrospective study., Methods: The subjects were patients with transient ischemic attack admitted to 13 stroke centers in Japan within 7 days of onset between 2008 and 2009. A total of 464 patients registered (292 men, 68.5±13.2 years old), and 421 of them (268 men, 68.8±13.1 years old) were included in the analyses. ODT was classified into the following 5 categories: <3 hours, 3 to 6 hours, 7 to 12 hours, 13 to 24 hours, and >24 hours., Results: There were 233 patients (55.3%) who visited a stroke center within 3 hours of symptom onset. Multiple ordinal logistic regression analysis revealed that motor weakness, speech disturbance, and duration of symptoms >10 minutes were independently associated with a short ODT. Furthermore, a history of transient ischemic attack and hypertension and a referral from another medical facility were independently associated with a long ODT. Patients with a higher ABCD2 score were likely to arrive at a stroke center more quickly., Conclusions: We identified several factors that were positively and negatively associated with the ODT in patients with transient ischemic attack.

Background: The purpose of this study was to elucidate the incidence and predictors of ischemic stroke or recurrent transient ischemic attack (TIA) during acute hospitalization in patients with TIA., Methods: We carried out a multicenter retrospective study to clarify the characteristics of in-patients with TIA. The subjects of this study were TIA patients admitted to 13 stroke hospitals within 7 days after onset between 2008 and 2009. TIA was defined as focal neurologic symptoms ascribable to a vascular etiology lasting less than 24 h. We investigated the incidence and predictors of ischemic events including ischemic stroke or recurrent TIA during hospitalization., Results: A total of 464 patients with TIA (292 men, 69 ± 13 years) were registered. Of those, 400 (86.2%) were admitted within 24 h of TIA onset. The mean length of hospital stay was 13 days. During hospitalization, 8 patients had ischemic strokes and 26 had recurrent TIAs. The leading subtype of 8 ischemic strokes was small vessel disease (n = 3) followed by cardioembolism (n = 2). Multiple logistic regression analysis showed that hypertension (OR: 3.41; 95% CI: 1.23-12.3), MRI-diffusion-weighted image positivity (OR: 2.49; 95% CI: 1.15-5.25), and hemiparesis (OR: 2.30; 95% CI: 1.02-5.88) were independently associated with ischemic events during hospitalization., Conclusions: In this study, 1.7% of patients with TIA had ischemic stroke during acute hospitalization, and the most common subtype was small vessel disease. Subsequent ischemic stroke and recurrent TIA were associated with hypertension, positive DWI findings, and hemiparesis., (© 2014 S. Karger AG, Basel.)

Background: This study investigated factors associated with the presence of acute ischemic lesions after transient ischemic attack (TIA), using diffusion-weighted imaging (DWI) data from a multicenter retrospective, observational study., Methods: Of the 464 patients admitted to 13 stroke centers in Japan within 7 days after TIA onset, 458 patients underwent a DWI examination in this registry. Patients were divided into those with acute ischemic lesions and those without. We analyzed associations between DWI lesions and baseline characteristics, including age, sex, comorbidities, large artery atherosclerosis (LAA), type and duration of symptoms, the presence of multiple occurrences of TIA within 90 days before hospital visits (multiple TIAs) and the time from symptom onset to DWI examination (time-to-DWI)., Results: Among the 458 patients (291 men, 68.4±13.2 years old), 374 (81.7%) underwent a DWI examination within the initial 24 hours after the symptom onset. DWI lesions were found in 96 patients (21.0%), and divided into a single lesion (56 patients, 12.2%) or multiple lesions (40 patients, 8.7%). The presence of DWI lesions had an association with male sex (odds ratio [OR] 1.84; 95% confidence interval [CI] 1.07-3.29), time-to-DWI longer than 24 hours (OR 2.96; CI 1.57-5.52), and intracranial LAA (OR 1.99; CI 1.02-3.79). The presence of a single DWI lesion had an association with atrial fibrillation (OR 2.70; CI 1.41-5.03), and multiple DWI lesions did with time-to-DWI longer than 24 hours (OR 6.20; CI 2.60-15.20), multiple TIAs (OR 3.04; CI 1.35-6.76), intracranial LAA (OR 3.63; CI 1.44-8.89), and extracranial LAA (OR 3.53; CI 1.08-10.78)., Conclusions: Acute ischemic lesions on DWI were associated with time-to-DWI and LAA in patients with classically defined TIA. Additionally, we identified some differences in relating factors between patients with single and multiple DWI lesions. These results indicate that time-to-DWI and DWI lesion pattern may be important for the diagnosis and management of TIA., (Copyright © 2013 National Stroke Association. Published by Elsevier Inc. All rights reserved.)

Background: The Essen stroke risk score is widely applied to predict the risk of recurrent ischemic stroke. We developed a modified Essen stroke risk score and validated it using a large prospective Effective Vascular Event REduction after STroke (EVEREST) registry including 3588 patients with ischemic stroke in Japan. Patients with cardioembolic stroke were excluded, and follow-up was one-year., Methods: The modified Essen stroke risk score was calculated from scores for waist circumference, stroke subtype by etiology, and gender in addition to age, hypertension, diabetes mellitus, previous myocardial infarction, other cardiovascular diseases except myocardial infarction and atrial fibrillation, peripheral artery disease, smoking, and previous stroke or transient ischemic attack. A multiple logistic regression model identified the predictors (each assigned one or two points) and provided c-statistics for the modified Essen stroke risk score. We considered two outcomes, recurrent ischemic stroke and cardiovascular events (defined as the combined outcomes of fatal or nonfatal stroke, myocardial infarction, nonfatal unstable angina, and cardiac death)., Results: Recurrent ischemic stroke occurred in 121 patients (3·7%) and cardiovascular events occurred in 133 (4·0%) within a year. The c-statistic (used for discrimination) was 0·632 for recurrent stroke and 0·640 for cardiovascular events. Patients scoring 6 or greater were classified as high risk, otherwise were classified as low risk. Kaplan-Meier analysis revealed that the modified risk score was more predictive than the Essen stroke risk score in both men and women., Conclusions: The modified Essen stroke risk score increased the ability of the Essen stroke risk score to predict recurrent cardiovascular events. Patients with a high modified Essen stroke risk score should be candidates for intensified secondary prevention strategies., (© 2012 The Authors. International Journal of Stroke © 2012 World Stroke Organization.)

Running exercise enhances neurogenesis in the normal adult and aged hippocampus. However, the effect of exercise on neurogenesis in the ischemic hippocampus is unclear. Here, we show that running exercise has different effects on ischemic and non-ischemic brain. Young (3-4-month-old) normotensive Wistar rats were used for this study. We administered bromodeoxyuridine (BrdU) to rats 7 days after the induction of transient forebrain ischemia or sham operation. BrdU-labeled cells were increased in the ischemic subgranular zone (SGZ) and granule cell layer (GCL) and double immunofluoresence showed approximately 80% of BrdU-labeled cells expressed neuronal markers. To assess the effect of running exercise on neurogenesis, BrdU-labeled cells in these regions were quantified after 1 day and 14 days. In sham-operated rats, the numbers of BrdU-labeled cells were significantly increased (2.2-fold) in the SGZ and GCL in response to running exercise. The numbers of BrdU-labeled cells were increased in response to ischemia, however, they were decreased 14 days after BrdU administration and running exercise accelerated the reduction in BrdU-labeled cells in ischemic rats. These findings suggest that running exercise has a negative effect on neurogenesis in the ischemic hippocampus. This may be important with respect to assessment of therapeutic approaches for functional recovery after stroke.

Several studies have suggested that cyclooxygenase-2 (COX-2) plays a role in ischemic neuronal death. Genetic disruption of COX-2 has been shown to reduce susceptibility to focal ischemic injury and N-methyl-d-aspartate-mediated neurotoxicity. The purpose of this study was to examine the effects of COX-2 deficiency on neuronal vulnerability after transient forebrain ischemia. Marked upregulation of COX-2 immunostaining in neurons was observed at the early stage and prominent COX-2 staining persisted in the CA1 medial sector and CA2 sector over 3 days after ischemia. The immunohistologic pattern of COX-2 staining in these sectors gradually condensed to a perinuclear location. The degree of hippocampal neuronal injury produced by global ischemia in COX-2-deficient mice was less than that in wild-type mice, coincident with attenuation of DNA fragmentation in the hippocampus. Also, treatment with a selective COX-2 inhibitor, nimesulide, after ischemia decreased hippocampal neuronal damages. These results of genetic disruption and chemical inhibition of cyclooxygenase-2 show that inhibition of COX-2 ameliorates selective neuronal death after transient forebrain ischemia in mice.

The authors compared temporal profiles of N-acetylaspartate (NAA) and the NAA/total creatine ratio with neuronal and astrocytic densities and with tissue atrophy in the hippocampal CA1 sector of gerbils after 5-minute bilateral forebrain ischemia and subsequent reperfusion for up to 6 months. The CA1 sector was dissected from 20- micro m lyophilized sections (n = 5) for NAA, phosphocreatine, and creatine assays using high-performance liquid chromatography. Adjacent 10- micro m sections were used for immunohistochemical analysis to follow neuronal and astrocytic responses. The NAA concentration was significantly (P<0.01) decreased after 7 days but leveled off thereafter. The NAA/total creatine (phosphocreatine + creatine) ratio was significantly decreased after 7 days and further decreased (P<0.05) after 6 months. Extensive neuronal damage developed beyond 7 days, while reactive astrogliosis progressed throughout the observation period. There was a good linear correlation (P<0.01) between astroglial density and the NAA/total creatine ratio beyond 7 days. The thickness of the CA1 sector was significantly reduced after 1 month and further reduced after 6 months. Although both NAA level and the NAA/total creatine ratio seemed to be indicators of neuronal damage, the latter could be influenced by reactive astrogliosis with progression of tissue atrophy.

Apolipoprotein E (APOE) deficiency has been shown to worsen neuronal injuries after cerebral ischemia. However, the molecular mechanism underlying the protective effect of APOE remains uncertain, even though several mechanisms including excitotoxicity, free radicals, and apoptosis have been cited as causes of selective neuronal vulnerability in cerebral ischemia. In the present study, we compared the vulnerability of cultured neurons prepared from APOE-knockout mice upon exposure to glutamate, hydrogen peroxide, and staurosporine. No significant difference in cell viability was observed after exposure to glutamate or staurosporine between APOE-deficient and wild-type mice. However, exposure to hydrogen peroxide significantly increased the level of cell death in APOE-deficient mice compared with that in wild-type mice. In the adult mice, after transient forebrain ischemia for 12 min, APOE-deficient mice showed more neuronal death than wild-type mice. Pretreatment of APOE-deficient mice with vitamin E for 2 months markedly reduced neuronal death caused by ischemia. The results suggested that APOE exerted the neuroprotective effect against ischemia through its antioxidant action, but not through mitigation of glutamate toxicity or blocking of apoptosis.

Recent studies have demonstrated that apolipoprotein E (APOE) deficiency worsened neuronal injuries after transient focal and global cerebral ischemia. However, the molecular mechanism underlying the protective effect of APOE remains uncertain, even though several mechanisms, including excitotoxicty, free radicals, and apoptosis, have been cited as causes of selective neuronal vulnerability in cerebral ischemia. In the present study, we first compared the vulnerability of cultured neurons prepared from APOE-knockout mice upon exposure to glutamate, hydrogen peroxide, and staurosporine. No significant difference in cell viability was observed after exposure to glutamate or staurosporine between APOE-deficient and wild-type mice. However, exposure to hydrogen peroxide significantly increased the level of cell death in APOE-deficient mice compared with that in wild-type mice. After transient forebrain ischemia for 12 min, APOE-deficient mice showed more neuronal death than wild-type mice. Pretreatment of APOE-deficient mice with vitamin E for 2 months markedly reduced neuronal death caused by ischemia. The results suggest that APOE exerted its neuroprotective effect against ischemia through its antioxidant action but not through mitigation of glutamate toxicity or blocking of apoptosis., (Copyright 2002 Wiley-Liss, Inc.)

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 the subgranular zone of the hippocampal dentate gyrus, the numbers of bromodeoxyuridine (BrdU)-positive cells increased approximately sixfold 7 days after ischemia. In double immunofluorescence staining, more than 80% of newborn cells expressed Musashi1, a marker of neural stem/progenitor cells, but only approximately 10% of BrdU-positive cells expressed glial fibrillary acidic protein (GFAP), a marker of astrocytes. The number of BrdU-positive cells markedly decreased 28 days after BrdU administration after ischemia, but it was still elevated compared with that of sham-operated rats. 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.