Masahiro Kamouchi

Properties of heterologously expressed hTRP3 channels in bovine pulmonary artery endothelial cells

1 We combined patch clamp and fura‐2 fluorescence methods to characterize human TRP3 (hTRP3) channels heterologously expressed in cultured bovine pulmonary artery endothelial (CPAE) cells, which do not express the bovine trp3 isoform (btrp3) but express btrp1 and btrp4. 2 ATP, bradykinin and intracellular InsP3 activated a non‐selective cation current (IhTRP3) in htrp3‐transfected CPAE cells but not in non‐transfected wild‐type cells. During agonist stimulation, the sustained rise in [Ca2+]i was significantly higher in htrp3‐transfected cells than in control CPAE cells. 3 The permeability for monovalent cations was PNa > PCs≈PK >> PNMDG and the ratio PCa/PNa was 1·62 ± 0·27 (n= 11). Removal of extracellular Ca2+ enhanced the amplitude of the agonist‐activated IhTRP3 as well as that of the basal current The trivalent cations La3+ and Gd3+ were potent blockers of IhTRP3 (the IC50 for La3+ was 24·4 ± 0·7 μM). 4 The single‐channel conductance of the channels activated by ATP, assessed by noise analysis, was 23 pS. 5 Thapsigargin and 2,5‐di‐tert‐butyl‐1,4‐benzohydroquinone (BHQ), inhibitors of the organellar Ca2+‐ATPase, failed to activate IhTRP3. U‐73122, a phospholipase C blocker, inhibited IhTRP3 that had been activated by ATP and bradykinin. Thimerosal, an InsP3 receptor‐sensitizing compound, enhanced IhTRP3, but calmidazolium, a calmodulin antagonist, did not affect IhTRP3. 6 It is concluded that hTRP3 forms non‐selective plasmalemmal cation channels that function as a pathway for agonist‐induced Ca2+ influx.

Antiplatelet therapy contributes to acute deterioration of intracerebral hemorrhage.

Objective: The purpose of this study was to examine the effect of antiplatelet therapy on the initial severity and the acute outcome of intracerebral hemorrhage (ICH). Methods: The authors reviewed records of 251 consecutive patients hospitalized in their cerebrovascular center within 24 hours after onset of ICH. Results: Fifty-seven patients (23%) had development of ICH during oral antiplatelet therapy. The major indication for antiplatelet therapy was the prevention of stroke recurrence (63%). As compared with patients without antiplatelet therapy, those who received antiplatelet therapy more frequently were aged 70 years or older (60% vs 35%; p < 0.001), had previous symptomatic ischemic stroke (54% vs 7%; p < 0.0001), had diabetes mellitus (26% vs 15%; p < 0.05), and had heart disease (32% vs 8%; p < 0.0001). Antiplatelet therapy was predictive of an increase in the hematoma volume by more than 40% on the second hospital day (hematoma enlargement, odds ratio [OR] 7.67, 95% CI 1.62 to 36.4) and the need for emergent surgical evacuation of the hematoma (OR 3.10, 95% CI 1.18 to 8.15). Antiplatelet therapy was an independent predictor for the occurrence of any of hematoma enlargement, emergent death, or evacuation surgery, which suggests that clinical deterioration occurs into the second hospital day (OR 7.45, 95% CI 2.46 to 22.5). Conclusions: Antiplatelet therapy seems to contribute to the acute clinical deterioration of intracerebral hemorrhage.

Postischemic Gene Transfer of Interleukin-10 Protects Against Both Focal and Global Brain Ischemia

Background—Gene therapy may be a promising approach for treatment of brain ischemia, although the efficiency of postischemic gene therapy is not established. Our goal in this study was to examine the effects of gene transfer of interleukin-10 (IL-10), an antiinflammatory cytokine, after induction of brain ischemia. Methods and Results—Brain ischemia was produced by either photochemical occlusion of distal middle cerebral artery for focal ischemia or bilateral carotid occlusion for global ischemia in spontaneously hypertensive rats. Adenoviral vectors encoding human IL-10 (AdIL10) or &bgr;-galactosidase (control) were injected into the lateral ventricle 90 or 60 minutes after focal or global ischemia. Five days after ischemia, IL-10, IL-1&bgr;, or tissue necrosis factor-&agr; in the cerebrospinal fluid, infarct volume, infiltrations of leukocytes/macrophages in the infarct area, or hippocampal neuronal damages were determined. The transduced IL-10 was released to the cerebrospinal fluid from the ventricular wall and increased to 7623±2965 pg/mL 5 days after AdIL10 transfection. Cerebral blood flow during ischemia was not different between treatments in either focal or global ischemia. Brain infarction of the AdIL10 group was significantly smaller and infiltrations of leukocytes and macrophages were fewer in the IL-10 treatment than control. Hippocampal neurons after global ischemia were more preserved, and the terminal deoxynucleotidyl transferase–mediated dUTP-biotin in situ nick end labeling–positive cells were diminished by the IL-10 gene transfer with attenuated IL-1&bgr; and augmented tissue necrosis factor-&agr;. Conclusions—Postischemic gene transfer of IL-10 into the lateral ventricle attenuated brain infarction and hippocampal damages, suggesting the promise for treatment of brain ischemia.

Free radical scavenger, edaravone, in stroke with internal carotid artery occlusion

BACKGROUND Edaravone has potent free radical quenching and antioxidant actions. The agent has been recently in commercial use for acute ischemic stroke patients. In this study, we investigated the therapeutic effect of edaravone on severe carotid-territorial stroke. METHODS Stroke patients with internal carotid artery occlusion and baseline NIH Stroke Scale Score > or =15 were treated for 14 days with drip intravenous infusion of edaravone (n=30) and were compared with a historical control cohort of similar patients (n=31). Glycerol was also administered to all patients in both groups. RESULTS Infarct volume (P<0.02) and midline shift (P<0.02) on CT performed on day 2 of the patients treated with edaravone were smaller than those without edaravone. For patients with edaravone, infarct volume (P<0.0001) and midline shift (P<0.0001) on days 5-7 were greater than those on day 2. Hemorrhagic transformation of infarcts on day 2 was less severe in patients with than without edaravone (P<0.03). Within 14 days after the onset of stroke, 6 patients with edaravone (20%) and 14 without edaravone (45%) died directly of stroke (P<0.03). Among all patients, only two treated with edaravone were independent without any assistance 8 weeks after the onset. CONCLUSIONS Edaravone was associated with delayed evolution of infarcts and edema in patients with severe carotid-territorial stroke and decreased mortality during the acute stage. The agent, however, failed to prevent evolution of infarcts and edema on later days, and did not significantly improve functional outcome among the surviving patients.

NAD(P)H Oxidases in Rat Basilar Arterial Endothelial Cells

Background and Purpose— Reactive oxygen species (ROS) may play a critical role in the regulation of vascular tone and development of vascular diseases, such as stroke. NAD(P)H oxidase is a major source of ROS in vascular cells, including endothelial cells. It has been considered that Nox2 and Nox4 are exclusively expressed among Nox homologues in the endothelial cells of noncerebral blood vessels. However, the precise molecular identity of the NAD(P)H oxidase in the endothelial cells of the cerebral arteries is not fully understood. We examined the expression of Nox homologues and their activation mechanism in the endothelial cells of the cerebral arteries. Methods— We isolated and cultured basilar artery endothelial cells (BAECs) of Sprague-Dawley rats. Expression of NAD(P)H oxidase was examined by reverse-transcription-polymerase chain reaction (RT-PCR) and immunohistological staining. Results— RT-PCR disclosed abundant expression of Nox4 with marginal Nox2 in BAEC. In addition, Nox1 was expressed highly both at mRNA and protein levels in BAECs. Immunohistological staining also showed the prominent expression of Nox1 in the endothelial cells of the basilar artery. With respect to the cytosolic components of NAD(P)H oxidases, BAECs expressed p67phox and, to a lesser extent, p47phox, Noxo1, and Noxa1. Both NADH and NADPH induced superoxide production of the BAEC membranes. The phagocyte-type cytosolic components, p47phox and p67phox, significantly enhanced the NADH-induced superoxide production of the BAEC membranes, whereas the components failed to increase the NADPH-induced superoxide production. Conclusions— Nox1 is highly expressed in the endothelial cells of the cerebral arteries along with Nox2 and Nox4, and the endothelial NAD(P)H oxidase of the cerebral arteries may have a unique activation mechanism by the phagocyte-type cytosolic components.

Secular Trends in Cardiovascular Disease and Its Risk Factors in Japanese Half-Century Data From the Hisayama Study (1961–2009)

Background— Changes in lifestyle and advances in medical technology during the past half century are likely to have affected the incidence and mortality of cardiovascular disease and the prevalence of its risk factors in Japan. Methods and Results— We established 5 cohorts consisting of residents aged ≥40 years in a Japanese community, in 1961 (n=1618), 1974 (n=2038), 1983 (n=2459), 1993 (n=1983), and 2002 (n=3108), and followed up each cohort for 7 years. The age-adjusted incidence of stroke decreased greatly, by 51% in men and by 43% in women, from the 1960s to the 1970s, but this decreasing trend slowed from the 1970s to the 2000s. Among the stroke subtypes, ischemic stroke in both sexes and intracerebral hemorrhage in men showed a similar pattern. Stroke mortality decreased as a result of the decline in incidence and a significant improvement in survival rate. Although the incidence of acute myocardial infarction did not change in either sex, disease mortality declined slightly in women. From the 1960s to the 2000s, blood pressure control among hypertensive individuals improved significantly and the smoking rate decreased, but the prevalence of glucose intolerance, hypercholesterolemia, and obesity increased steeply. Conclusions— Our findings suggest that in Japanese, the decreasing trends in the incidence of ischemic stroke have recently slowed down, and there has been no clear change in the incidence of acute myocardial infarction, probably because the benefits of hypertension control and smoking cessation have been negated by increasing metabolic risk factors. # Clinical Perspective {#article-title-30}Background— Changes in lifestyle and advances in medical technology during the past half century are likely to have affected the incidence and mortality of cardiovascular disease and the prevalence of its risk factors in Japan. Methods and Results— We established 5 cohorts consisting of residents aged ≥40 years in a Japanese community, in 1961 (n=1618), 1974 (n=2038), 1983 (n=2459), 1993 (n=1983), and 2002 (n=3108), and followed up each cohort for 7 years. The age-adjusted incidence of stroke decreased greatly, by 51% in men and by 43% in women, from the 1960s to the 1970s, but this decreasing trend slowed from the 1970s to the 2000s. Among the stroke subtypes, ischemic stroke in both sexes and intracerebral hemorrhage in men showed a similar pattern. Stroke mortality decreased as a result of the decline in incidence and a significant improvement in survival rate. Although the incidence of acute myocardial infarction did not change in either sex, disease mortality declined slightly in women. From the 1960s to the 2000s, blood pressure control among hypertensive individuals improved significantly and the smoking rate decreased, but the prevalence of glucose intolerance, hypercholesterolemia, and obesity increased steeply. Conclusions— Our findings suggest that in Japanese, the decreasing trends in the incidence of ischemic stroke have recently slowed down, and there has been no clear change in the incidence of acute myocardial infarction, probably because the benefits of hypertension control and smoking cessation have been negated by increasing metabolic risk factors.

Proteinuria and clinical outcomes after ischemic stroke

Objectives: The impact of chronic kidney disease (CKD) on clinical outcomes after acute ischemic stroke is still not fully understood. The aim of the present study was to elucidate how CKD and its components, proteinuria and low estimated glomerular filtration rate (eGFR), affect the clinical outcomes after ischemic stroke. Methods: The study subjects consisted of 3,778 patients with first-ever ischemic stroke within 24 hours of onset from the Fukuoka Stroke Registry. CKD was defined as proteinuria or low eGFR (<60 mL/min/m2) or both. The study outcomes were neurologic deterioration (≥2-point increase in the NIH Stroke Scale during hospitalization), in-hospital mortality, and poor functional outcome (modified Rankin Scale score at discharge of 2 to 6). The effects of CKD, proteinuria, and eGFR on these outcomes were evaluated using a multiple logistic regression analysis. Results: CKD was diagnosed in 1,320 patients (34.9%). In the multivariate analyses after adjusting for confounding factors, patients with CKD had significantly higher risks of neurologic deterioration, in-hospital mortality, and poor functional outcome (p <0.001 for all). Among the CKD components, a higher urinary protein level was associated with an elevated risk of each outcome (p for trend < 0.001 for all), but no clear relationship between the eGFR level and each outcome was found. Conclusions: CKD is an important predictor of poor clinical outcomes after acute ischemic stroke. Proteinuria independently contributes to the increased risks of neurologic deterioration, mortality, and poor functional outcome, but the eGFR may not be relevant to these outcomes.

Novel therapeutic strategies targeting innate immune responses and early inflammation after stroke

Post‐ischemic inflammation is an essential step in the progression of ischemic stroke. This review focuses on the function of infiltrating immune cells, macrophages, and T cells, in ischemic brain injury. The brain is a sterile organ; however, the activation of Toll‐like receptor (TLR) 2 and TLR4 is pivotal in the beginning of post‐ischemic inflammation. Some endogenous TLR ligands are released from injured brain cells, including high mobility group box 1 and peroxiredoxin family proteins, and activate the infiltrating macrophages and induce the expression of inflammatory cytokines. Following this step, T cells also infiltrate into the ischemic brain and mediate post‐ischemic inflammation in the delayed phase. Various cytokines from helper T cells and γδT cells function as neurotoxic (IL‐23/IL‐17, IFN‐γ) or neuroprotective (IL‐10, IL‐4) mediators. Novel neuroprotective strategies should therefore be developed through more detailed understanding of this process and the regulation of post‐ischemic inflammation.

Prestroke Glycemic Control Is Associated With the Functional Outcome in Acute Ischemic Stroke The Fukuoka Stroke Registry

Background and Purpose— Diabetes mellitus is an established risk factor for stroke. However, it is uncertain whether prestroke glycemic control (PSGC) status affects clinical outcomes of acute ischemic stroke. The aim of this study was to elucidate the association between PSGC status and neurological or functional outcomes in patients with acute ischemic stroke. Methods— From the Fukuoka Stroke Registry (FSR), a multicenter stroke registry in Japan, 3627 patients with first-ever ischemic stroke within 24 hours after onset were included in the present analysis. The patients were categorized into 4 groups based on their PSGC status: excellent (hemoglobin [Hb] A1c on admission <6.2%), good (6.2–6.8%), fair (6.9–8.3%) and poor (≥8.4%). Study outcomes were neurological improvement (≥4 points decrease in the National Institutes of Health Stroke Scale [NIHSS] score during hospitalization or 0 points on NIHSS score at discharge), neurological deterioration (≥1 point increase in NIHSS score) and poor functional outcome (death or dependency at discharge, modified Rankin Scale 2–6). Results— The age- and sex-adjusted ORs for neurological improvement were lower, and those for neurological deterioration and a poor functional outcome were higher in patients with poorer PSGC status. After adjusting for multiple confounding factors, these trends were unchanged (all probability values for trends were <0.002). These findings were comparable in patients with noncardioembolic and cardioembolic infarctions. Conclusions— In ischemic stroke patients, HbA1c on admission was an independent significant predictor for neurological and functional outcomes.

PDGF Receptor β Signaling in Pericytes Following Ischemic Brain Injury

Platelet derived growth factor (PDGF)-B plays a neuroprotective role in brain damages, including ischemic stroke. It has been suggested recently that PDGF receptor β (PDGFRβ) expressed in brain pericytes as well as in neurons and astrocytes may mediate the neuroprotective role of PDGF-B. The aims of this study were to elucidate the roles of PDGFRβ signaling in brain pericytes after ischemic stroke. In a rat middle cerebral artery occlusion (MCAO) model, PDGFRβ expression was induced specifically in the pericytes in peri-infarct areas and its level was gradually increased. PDGF-B induced marked phosphorylation of Akt in cultured brain pericytes. Consistently, PDGF-B was upregulated in endothelial cells in per-infarct areas and Akt was strongly phosphorylated in the PDGFRβ-expressing pericytes in periinfarct areas after MCAO. In the cultured pericytes, PDGF-B induced cell growth and anti-apoptotic responses through Akt. Furthermore, PDGF-B significantly increased the expression of nerve growth factor (NGF) and neurotrophin-3 (NT-3) through Akt in the pericytes. Thus, the PDGFRβ-Akt signaling in brain pericytes may play various important roles leading to neuroprotection after ischemic stroke.