Kazuo Yamashiro

Neurogenesis After Transient Global Ischemia in the Adult Hippocampus Visualized by Improved Retroviral Vector

Background and Purpose— Neurogenesis has been observed in the dentate gyrus of the adult hippocampus; however, the mechanisms involved in this process are still only partly understood. In this study, we visualized the proliferation, migration, and differentiation of neuronal progenitor cells in the dentate gyrus induced by ischemic stress using improved retroviral vector. Methods— Improved retroviral vector expressing enhanced green fluorescent protein (EGFP) as a transgene was injected into the dentate gyrus of adult Mongolian gerbils. After 48 hours, transient global ischemia (TGI) was induced by bilateral common carotid artery occlusion for 5 minutes using aneurysm clips. The morphological and immunohistological features of newly-generated cells in the dentate gyrus were analyzed at various times thereafter. Results— At 48 hours after viral injection, almost all EGFP-positive dividing cells were found in the subgranule layer (SGL). These cells proliferated and migrated to the granule cell layer (GCL), expressing the developing neuronal markers polysialic acid and doublecortin, and differentiated to neuronal nuclei–positive or calbindin-positive mature granule cells at 30 days after TGI or sham-operation. The number of GFP-positive cells in the GCL was significantly higher (P < 0.05) in the ischemic animals at 30 days than in sham-operated gerbils. Conclusions— We saw neurogenesis in the adult dentate gyrus. Furthermore, we showed that ischemic stress promoted the proliferation and normal development of neurons at this site.

Prognosis of Parkinson's disease: Time to stage III, IV, V, and to motor fluctuations

We report a long‐term outcome on a large cohort of Japanese patients with Parkinsons disease (PD). A total of 1,768 (793 men, 975 women) consecutive patients visited our clinic from 1 January 1989 to 31 December 2002. Among them, 1,183 patients (531 men, 652 women) came to our clinic within 5 years from the onset of disease and at the Hoehn & Yahr Stage III or less at the first visit. Long‐term outcome was evaluated in this subcohort of the patients. We examined the duration to reach Stage III, IV, and V, and the duration to develop wearing off and dyskinesia. Time to reach Stage III was slightly but significantly shorter in women, in that 23.8% of men and 35.3% of women reached Stage III by the end of the 5th year; 49.7% of men and 63.3% of women reached Stage III by the end of the 10th year, and 88.9% of men and 79.9% of women by the end of the 15th year (P < 0.001). Also, durations to develop wearing off and dyskinesia were shorter in women compared to men. These data suggest that the disease progression may be slightly faster for women. Young‐onset patients showed significantly longer duration to reach Stage III, IV, and V but shorter duration to develop wearing off and dyskinesia. Not many studies are available in the literature on the long‐term outcome of PD, and our data would be useful as a reference.

Impact of diabetes and prediabetes on the short-term prognosis in patients with acute ischemic stroke.

OBJECTIVE We aimed to explore the association between abnormal glucose metabolism such as diabetes, prediabetes, and short-term prognosis in patients with acute ischemic stroke. METHODS Of 242 consecutive acute ischemic stroke patients, a 75-g oral glucose tolerance test was administered to 116 patients without previously diagnosed diabetes. One hundred forty patients were classified into diabetes, 52 patients were prediabetes (impaired glucose tolerance or impaired fasting glucose or both), and 50 patients were normal glucose tolerance (NGT). The association between each glycemic status and early neurological deterioration (END; increase in the NIH Stroke Scale (NIHSS) of ≥2 points during the first 14days after admission) or poor short-term outcome (30-day modified Ranking Scale [mRS] score 2-6) was evaluated. RESULTS In multivariable analysis, the risk of END was significantly higher in the diabetes group than in the NGT group (ORs=11.354; 95% CI, 1.492-86.415; p=0.019), even after adjustment for possible confounding factors (ORs=12.769; 95% CI, 1.361-119.763; p=0.026). Similar but insignificant associations were observed between prediabetes and NGT groups (ORs=6.369; 95% CI, 0.735-55.177; p=0.093). The risk of poor outcome (30-day mRS 2-6) was significantly higher in the diabetes group (ORs=3.667; 95% CI, 1.834-7.334; p<0.001) than in the NGT group, even after adjusting for confounding factors (ORs=3.340; 95% CI, 1.361-8.195; p=0.008). Similar but insignificant associations were observed between prediabetes and NGT groups (ORs=2.058; 95% CI, 0.916-4.623; p=0.08). CONCLUSION In our patient population, both diabetes and prediabetes were associated with a poor early prognosis after acute ischemic stroke.

The frequency of cardiac valvular regurgitation in Parkinson's disease

To investigate the frequency of cardiac valve regurgitation related with low dose dopamine agonists in patients with Parkinsons disease (PD), echocardiograms were analyzed in 527 consecutive PD patients (448 patients treated with dopamine agonists, 79 patients never treated with dopamine agonists as age‐matched controls). The frequency of mild or above mild regurgitation of the aortic valve (AR) was significantly higher in the cabergoline group (13.7%, P < 0.05) compared with the controls (2.5%). Odds ratio adjusted by age and sex for AR was significantly higher in the cabergoline group (OR, 6.45; 95% CI, 1.46–28.60; P = 0.01): odds ratio was significantly higher in patients treated with higher daily doses (OR, 14.41; 95% CI, 3.08–67.38; P = 0.0007) and higher cumulative doses (OR, 15.29; 95% CI, 3.19–73.18; P = 0.0006). No statistical difference was identified in the frequency of the tricuspid and mitral regurgitation. None of the other dopamine agonist groups including pergolide gave higher frequency or higher odds ratio compared with the controls. None of our patients showed severe regurgitation or was operated for valvular heart disease. The question as to whether or not longer duration of low dose dopamine agonist treatment would yield the same results needs further studies.

Gut dysbiosis is associated with metabolism and systemic inflammation in patients with ischemic stroke

The role of metabolic diseases in ischemic stroke has become a primary concern in both research and clinical practice. Increasing evidence suggests that dysbiosis is associated with metabolic diseases. The aim of this study was to investigate whether the gut microbiota, as well as concentrations of organic acids, the major products of dietary fiber fermentation by the gut microbiota, are altered in patients with ischemic stroke, and to examine the association between these changes and host metabolism and inflammation. We analyzed the composition of the fecal gut microbiota and the concentrations of fecal organic acids in 41 ischemic stroke patients and 40 control subjects via 16S and 23S rRNA-targeted quantitative reverse transcription (qRT)-PCR and high-performance liquid chromatography analyses, respectively. Multivariable linear regression analysis was subsequently performed to evaluate the relationships between ischemic stroke and bacterial counts and organic acid concentrations. Correlations between bioclinical markers and bacterial counts and organic acids concentrations were also evaluated. Although only the bacterial counts of Lactobacillus ruminis were significantly higher in stroke patients compared to controls, multivariable analysis showed that ischemic stroke was independently associated with increased bacterial counts of Atopobium cluster and Lactobacillus ruminis, and decreased numbers of Lactobacillus sakei subgroup, independent of age, hypertension, and type 2 diabetes. Changes in the prevalence of Lactobacillus ruminis were positively correlated with serum interleukin-6 levels. In addition, ischemic stroke was associated with decreased and increased concentrations of acetic acid and valeric acid, respectively. Meanwhile, changes in acetic acid concentrations were negatively correlated with the levels of glycated hemoglobin and low-density lipoprotein cholesterol, whereas changes in valeric acid concentrations were positively correlated with the level of high sensitivity C-reactive protein and with white blood cell counts. Together, our findings suggest that gut dysbiosis in patients with ischemic stroke is associated with host metabolism and inflammation.

Visceral fat accumulation is associated with cerebral small vessel disease

Obesity is associated with the risk of coronary artery disease and stroke. Visceral fat plays a significant role in the atherogenic effects of obesity. Whether visceral fat accumulation, as measured by computed tomography (CT), is an independent risk factor for the presence of cerebral small vessel disease (SVD) was investigated.

Cerebral Microbleeds Are Associated with Worse Cognitive Function in the Nondemented Elderly with Small Vessel Disease

Background: Cerebral small vessel disease (SVD) is a leading cause of cognitive decline in the elderly. Cerebral microbleeds (CMBs) have emerged as an important manifestation of cerebral SVD, in addition to lacunar infarcts and white matter lesions (WMLs). We investigated whether the presence and location of CMBs in elderly subjects were associated with cognitive function, independent of lacunar infarcts and WMLs. Methods: One hundred and forty-eight nondemented elderly with SVD, defined as the presence of lacunar infarcts and/or WMLs on magnetic resonance imaging (MRI), were studied. Executive function and global cognition were assessed by the Frontal Assessment Battery (FAB) and Mini-Mental State Examination (MMSE), respectively. The differences in the scores for the FAB and MMSE between CMB-positive and CMB-negative subjects were calculated after adjusting for possible confounders. Results: The mean age of the subjects was 72.4 w 8.6 years. CMBs were detected in 48 subjects (32%), with a mean number of CMBs per subject of 1.6 (range 0-31). Among CMB-positive subjects, 42 (87.5%) had CMBs in deep or infratentorial regions with or without lobar CMBs, and 6 (12.5%) had CMBs in strictly lobar regions. The presence of CMBs was significantly associated with FAB and MMSE scores after adjustment for age, years of education, brain volume and the presence of lacunar infarcts (for the FAB) or severe WMLs (for the MMSE). The presence of CMBs in the basal ganglia, in the thalamus or in the lobar regions was associated with FAB scores, while that in the lobar regions was associated with MMSE scores. However, there was no association between CMBs in the infratentorial regions and cognitive parameters. Conclusions: In nondemented elderly with SVD on MRI, the presence of CMBs was independently associated with worse executive and global cognitive functions. CMBs seemed to reflect hypertensive microangiopathy in this population, and CMBs in specific areas may play an important role in cognitive function. i 2014 S. Karger AG, Basel

Effects of Pioglitazone for Secondary Stroke Prevention in Patients with Impaired Glucose Tolerance and Newly Diagnosed Diabetes: The J-SPIRIT Study.

AIM Prediabetes is an independent risk factor for future stroke. However, no effective treatment has yet been established for the recurrence of stroke in patients with prediabetes. Here we investigated the effects of pioglitazone, a potent peroxisome proliferator-activated receptor-gamma agonist, for the reduction of recurrent stroke in patients with prediabetes. METHODS Participants were patients who had a symptomatic ischemic stroke or transient ischemic attack (TIA) without a history of type 2 diabetes mellitus and who were diagnosed to have IGT or newly diagnosed diabetes by a 75-g oral glucose tolerance test. These patients were randomized to either receive or not receive pioglitazone. The primary endpoint was a recurrence of ischemic stroke. RESULTS A total of 120 patients were enrolled in the study. Sixty-three patients received pioglitazone and 57 were enrolled in the control group that did not receive pioglitazone. The majority of patients (68.3%) were prescribed 15 mg of pioglitazone, while the remaining patients (31.7%) were treated with 30 mg of pioglitazone. Over a median follow-up period of 2.8 years, treatment with pioglitazone was found to be associated with a lower rate of the primary endpoint (recurrence of stroke) than that observed in the control group [event rate=4.8% pioglitazone vs 10.5% control, hazard ratio=0.62, 95% confidence interval 0.13-2.35, p=0.49]. However, differences were not statistically significant. CONCLUSIONS While this study was too underpowered to determine the effect of pioglitazone, the result failed to show beneficial effects in patients of ischemic stroke or TIA with impaired glucose tolerance and newly diagnosed diabetes.

Chronic brain ischemia induces the expression of glial glutamate transporter EAAT2 in subcortical white matter.

Glutamate plays a central role in brain physiology and pathology. The involvement of excitatory amino acid transporters (EAATs) in neurodegenerative disorders including acute stroke has been widely studied, but little is known about the role of glial glutamate transporters in white matter injury after chronic cerebral hypoperfusion. The present study evaluated the expression of glial (EAAT1 and EAAT2) and neuronal (EAAT3) glutamate transporters in subcortical white matter and cortex, before and 3-28 days after the ligation of bilateral common carotid arteries (LBCCA) in rat brain. K-B staining showed a gradual increase of demyelination in white matter after ischemia, while there was no cortical involvement. Between 3 and 7 days after LBCCA, a significant increase in EAAT2 protein levels was observed in the ischemic brain and the number of EAAT2-positive cells also significantly increased both in the cortical and white matter lesions. EAAT2 was detected in glial-fibrillary acidic protein (GFAP)-positive astrocytes in both the cortex and white matter, but not in neuronal and oligodendroglial cells. EAAT1 was slightly elevated after ischemia only in the white matter, but EAAT3 was at almost similar levels both in the cortex and white matter after ischemia. A significant increase in EAAT2 expression level was also noted in the deep white matter of chronic human ischemic brain tissue compared to the control group. Our findings suggest important roles for up-regulated EAAT2 in chronic brain ischemia especially in the regulation of high-affinity of extracellular glutamate and minimization of white matter damage.

Aging, aortic arch calcification, and multiple brain infarcts are associated with aortogenic brain embolism.

Background: Mobile or ulcerated aortic plaques (MUAPs) on transesophageal echocardiography (TEE) can cause aortogenic brain embolism. Aortic arch calcification (AoAC) on chest X-ray represents systemic atherosclerosis. This study focused on AoAC on chest X-ray and its link with atheromatous aortic plaques (AAPs) on TEE in stroke patients. The aim of the present study was to assess the relationship between AoAC and AAPs in unexplained stroke patients. Methods: A total of 178 patients (mean age: 64 ± 15 years; 115 males) with ischemic stroke who underwent TEE were enrolled. The patients were classified based on TEE findings: (1) AAPs <4 mm; (2) AAPs ≥4 mm, and (3) MUAPs. The extent of AoAC on chest X-ray was divided into 4 grades (0-3). Clinical characteristics including AoAC were compared among the 3 groups. Multiple logistic regression analysis was performed to identify the independent factors associated with MUAPs. An original diagnostic criterion was defined as a potential indicator of MUAPs in unexplained stroke patients. Results: 104 (58%) patients had AAPs <4 mm, 46 (26%) had AAPs ≥4 mm, and 28 (16%) had MUAPs. Older age (OR: 1.14; 95% CI: 1.06-1.24; p = 0.001), AoAC (OR: 2.35; 95% CI: 1.30-4.24; p = 0.005), and multiple infarctions in multiple vascular territories (VTs) demonstrated on diffusion-weighted imaging (DWI) (OR: 2.58; 95% CI: 1.35-4.92; p = 0.004) were independently associated with MUAPs. The CAM score was defined as consisting of the degree of AoAC (0-3 points), age (≥70 years: 1 point), and DWI findings (multiple infarctions in 1 VT: 1 point; 2 VTs: 2 points; more than 3 VTs: 3 points). The prevalence of MUAPs was substantially increased in patients with medium risk (CAM score 3-4, OR: 7.68; 95% CI: 2.89-20.44; p < 0.001) and high risk (CAM score 5-7, OR: 20.63; 95% CI: 5.12-83.06; p < 0.001). Conclusions: Older age, advanced AoAC, and multiple infarctions in multiple VTs are associated with aortogenic brain embolism. The CAM score can be useful for the diagnosis of aortogenic brain embolism.