Yutaka Nishiyama

Nippon Medical School, Sendai, Kagoshima-ken, Japan

Are you Yutaka Nishiyama?

Claim your profile

Publications (10)16.87 Total impact

  • Article: Effects of eicosapentaenoic acid on asymmetric dimethylarginine in patients in the chronic phase of cerebral infarction: a preliminary study.
    Hiroshi Hagiwara, Yutaka Nishiyama, Yasuo Katayama
    [show abstract] [hide abstract]
    ABSTRACT: Eicosapentaenoic acid (EPA) possesses a variety of pharmacologic actions and demonstrates protective efficacy against stroke. Meanwhile, asymmetric dimethylarginine (ADMA) is an endogenous nitric oxide synthase inhibitor and is thereby considered one of the risk factors of cardiovascular disease. The effects of the EPA treatment on ADMA in patients in the chronic phase of cerebral infarction accompanied by dyslipidemia were investigated. Study subjects were individuals with either atherothrombotic or lacunar cerebral infarction in the chronic phase accompanied by dyslipidemia, of which the onset was at least 4 weeks earlier. Lipid, fatty acid, and ADMA levels in the blood were measured at EPA 1800 mg per day and compared both before and after treatment. Twenty subjects were included in the study (average age, 71.9 ± 8.9 years). Of these 20 cases, eight were atherothrombotic and 12 were lacunar. Moreover, 17 cases were accompanied by hypertension and 10 cases were accompanied by diabetes mellitus. After EPA treatment (average duration of treatment, 143 ± 42 days), EPA increased from 65.1 ± 38.1 μg/mL to 201.1 ± 73.4 μg/mL (P < .01). Arachidonic acid (AA) decreased from 149.1 ± 34.8 μg/mL to 129.7 ± 22.3 μg/mL (P < .01), and the EPA/AA ratio increased from 0.45 ± 0.26 to 1.55 ± 0.46 (P < .01). ADMA decreased from 0.49 ± 0.07 nmol/mL before treatment to 0.46 ± 0.05 nmol/mL after treatment (P < .01). EPA treatment in patients in the chronic phase of cerebral infarction leads to a decrease in ADMA in the blood, suggesting that EPA improves vascular endothelial function and therefore supports the protective efficacy against cerebral infarction.
    Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association 01/2011; 20(5):474-8.
  • Article: Correlation between insulin resistance and white matter lesions among non-diabetic patients with ischemic stroke
    [show abstract] [hide abstract]
    ABSTRACT: Objective: We investigated whether a correlation exists between insulin resistance and the severity of cerebral white matter lesions among non-diabetic patients with ischemic stroke.Methods: The subjects were 105 consecutive patients without diabetes who were hospitalized due to non-cardioembolic stroke. The insulin resistance was evaluated by a homeostasis model assessment of insulin resistance (HOMA-IR). The degrees of periventricular hyperintensity (PVH) and deep and subcortical white matter hyperintensity (DSWMH) were evaluated by the brain MRI. The HOMA-IR values ?2?5 were indicative of the insulin resistance.Results: The presence of PVH and DSWMH were 86?7 and 83?8%, respectively. The ratio of insulin resistance increased with higher grades of PVH and DSWMH. The HOMA-IR level in grade 3 PVH was significantly higher than those in grades 0 and 1. The HOMA-IR level in grade 3 DSWMH was significantly higher than those in grades 0?2. Multiple linear regression analysis showed that HOMA-IR was significantly associated with PVH or DSWMH.Conclusion: It was found that insulin resistance correlated with white matter lesions among non-diabetic patients with non-cardiogenic ischemic stroke.Objective: We investigated whether a correlation exists between insulin resistance and the severity of cerebral white matter lesions among non-diabetic patients with ischemic stroke.Methods: The subjects were 105 consecutive patients without diabetes who were hospitalized due to non-cardioembolic stroke. The insulin resistance was evaluated by a homeostasis model assessment of insulin resistance (HOMA-IR). The degrees of periventricular hyperintensity (PVH) and deep and subcortical white matter hyperintensity (DSWMH) were evaluated by the brain MRI. The HOMA-IR values ?2?5 were indicative of the insulin resistance.Results: The presence of PVH and DSWMH were 86?7 and 83?8%, respectively. The ratio of insulin resistance increased with higher grades of PVH and DSWMH. The HOMA-IR level in grade 3 PVH was significantly higher than those in grades 0 and 1. The HOMA-IR level in grade 3 DSWMH was significantly higher than those in grades 0?2. Multiple linear regression analysis showed that HOMA-IR was significantly associated with PVH or DSWMH.Conclusion: It was found that insulin resistance correlated with white matter lesions among non-diabetic patients with non-cardiogenic ischemic stroke.
    Neurological Research 08/2010; 32(7):743-747. · 1.52 Impact Factor
  • Source
    Article: Cerebral infarction in a patient with macrothrombocytopenia with leukocyte inclusions (MTCP, May-Hegglin anomaly/Sebastian syndrome).
    [show abstract] [hide abstract]
    ABSTRACT: We report on a 78-year-old woman patient with macrothrombocytopenia with leukocyte inclusions (MTCP, May-Hegglin anomaly/Sebastian syndrome), who had no history of hemorrhagic symptoms and had a platelet count of 10,000 or less, but had a cerebral infarction. The patient was found to have idiopathic thrombocytopenic purpura, hypertension, and atrial fibrillation 16 years ago, yet received no medication. She was found to have had a cerebral infarction with aphasia as the chief complaint and was admitted to our hospital. Thrombocytopenia was found in three family members. Blood examinations revealed normal bleeding time and platelet aggregation ability. The patient was found to have the triad of giant platelets, thrombocytopenia, and inclusion bodies in leukocytes. Genetic analysis showed a mutation of the MYH-9 gene in the patients second daughter. Consequently, this patient received a diagnosis of MTCP. There have only been a few reports of the onset of thrombosis in patients with MTCP and no reports of the onset of cerebral infarction. Our report is the first case of MTCP in a patient with cerebral infarction.
    Journal of Nippon Medical School 09/2008; 75(4):228-32.
  • Article: Effects of long-term administration of HMG-CoA reductase inhibitor, atorvastatin, on stroke events and local cerebral blood flow in stroke-prone spontaneously hypertensive rats.
    [show abstract] [hide abstract]
    ABSTRACT: The objective of this study was to determine whether the long-term administration of an HMG-CoA reductase inhibitor, atorvastatin, confers protective effects against stroke events in stroke-prone spontaneously hypertensive rats (SHRSPs). Atorvastatin (2 mg/kg, 20 mg/kg) or vehicle was orally administered to 8-week-old SHRSPs for 11 weeks. The survival ratio and stroke incidence were calculated, and plasma lipids and plasma levels of asymmetric dimethylarginine (ADMA), a circulating endogenous competitive inhibitor of NO synthase, were measured after sacrifice. The effect of atorvastatin on local cerebral blood flow (l-CBF) was also determined in 13-week-old SHRSPs after treatment with 20 mg/kg atorvastatin daily for 5 weeks. The survival ratios at 19 weeks of age were 15, 30, and 50% in the vehicle, low-dose (2 mg/kg), and high-dose groups (20 mg/kg), respectively. The survival ratio was significantly higher in the high-dose group than in the vehicle group. The incidence of stroke was significantly lower in the high-dose group than in the vehicle group. The levels of ADMA were 0.81+/-0.18 (mean+/-S.D.), 0.62+/-0.09, and 0.61+/-0.06 micromol/l in the vehicle, low-dose, and high-dose groups, respectively. Atorvastatin administration significantly reduced the ADMA levels without affecting the levels of plasma lipids. The level of l-CBF tended to be higher in the treated group, but not to a significant extent. Thus, atorvastatin was determined to confer a protective effect against hypertension-based stroke. The data suggest that the efficacy of the statin for stroke protection may be partially involved in the improvement of endothelial function via NO production and reduction of ADMA. Statins may confer useful protection against not only atherosclerosis-based stroke, but also hypertension-based stroke.
    Brain Research 10/2007; 1169:125-32. · 2.73 Impact Factor
  • Article: Effect of ischemic preconditioning on cerebral blood flow after subsequent lethal ischemia in gerbils.
    [show abstract] [hide abstract]
    ABSTRACT: Ischemic tolerance, the phenomenon where a sublethal ischemic preconditioning protects the brain against a subsequent lethal ischemia, has been widely studied. Studies have been done on cerebral blood flow levels prior to the lethal ischemia, but the hemodynamic pattern after global ischemia with ischemic preconditioning has not been reported. Sequential changes in regional cerebral blood flow (rCBF) in gerbil hippocampus after 5 min global ischemia with or without 2 min ischemic preconditioning were studied to determine if ischemic preconditioning affects rCBF. Four different treatments were given: (1) sham-operated, (2) 2 min ischemia, (3) non-preconditioned, and (4) preconditioned. Groups (1) and (2) (both groups n = 5) were given a 24-h recovery period and the rCBF was measured for baseline values. 24 h after sham-operation (3) and 2 min ischemia (4), gerbils were subjected to 5 min ischemia followed by 1 h, 6 h, 1-day or 7-day reperfusion periods (all groups n = 5). Although no regional difference was observed in the recovery pattern of rCBF, the values of rCBF were significantly higher in the preconditioned group throughout whole brain regions including hippocampus. These results indicate that ischemic preconditioning facilitated the recovery of rCBF after 5 min global ischemia. It needs further study to determine whether the protecting effects of preconditioning relate to the early recovery of rCBF or not. However, our results could be interpreted that the early recovery of rCBF may lead to benefits for cell survival in the CA1 neuron, probably facilitating other protecting mechanisms.
    Life Sciences 04/2006; 78(15):1713-9. · 2.53 Impact Factor
  • Article: Stroke protection by atorvastatin treatment in stroke-prone spontaneously hypertensive rats (SHRSPs):1. rate of morbidity and mortality of stroke, and serum asymmetric dimethyl arginine (ADMA)
    Journal of Cerebral Blood Flow &#38 Metabolism 07/2005; · 5.01 Impact Factor
  • Article: Effect of glycerol on ischemic cerebral edema assessed by magnetic resonance imaging.
    [show abstract] [hide abstract]
    ABSTRACT: The aim of this study is to assess the anticerebral edema effect of glycerol on a large cerebral infarction with magnetic resonance imaging (MRI). Glycerol, which is widely used as an osmotic agent against cerebral edema, could exacerbate brain tissue shift, since it has been suggested that glycerol might shrink a noninfarcted hemisphere and worsen the mass effect after a large hemispheric cerebral infarction. To investigate these issues, changes in a large hemispheric infarction with cerebral edema were studied using MRI before and after glycerol administration. Infarct volumes, normal brain tissue volumes and lateral ventricle volumes, in addition to signal intensities of T(2)-weighted images, were measured in six patients before and after administration of 300 ml of glycerol. Ventricle volumes were significantly increased (p=0.0015) and the T(2) signal intensity of the post-treatment ischemic region decreased after glycerol administration. In contrast, no significant differences in either cerebral volume or T(2) signal intensity were seen in the noninfarcted hemisphere before and after administration. Our data suggest that glycerol does not exacerbate the mass effect on a large hemispheric infarction.
    Journal of the Neurological Sciences 06/2003; 209(1-2):69-74. · 2.35 Impact Factor
  • Article: Neuroprotective effect of NS-7, a novel Na+ and Ca2+ channel blocker, in a focal ischemic model in the rat.
    [show abstract] [hide abstract]
    ABSTRACT: NS-7 is a novel, voltage-dependent Na(+) and Ca(2+) channel blocker. This study evaluated the in vivo neuroprotective effect of NS-7 in a rat transient focal ischemic model when administered during occlusion. Left middle cerebral artery occlusion was induced in adult male Sprague-Dawley rats for 120 min using an intraluminal thread method. The rats received a single intravenous injection of NS-7 or saline (control group) just after the onset of ischemia, and at 30, 60 and 120 min after ischemia. Their brains were removed after 48 h reperfusion, sectioned, and stained with hematoxylin and eosin. Animals were evaluated by neurological examination at 120 min ischemia and 48 h reperfusion. Infarcted cortex and striatum were measured quantitatively and infarction volumes were calculated. Cortical infarction volumes were 128+/-74 (NS-7) and 214+/-64 mm(3) (control) immediately after the ischemia group, 155+/-48 (NS-7) and 225+/-12 mm(3) (control) after the 30 min group, 160+/-54 (NS-7) and 225+/-48 mm(3) (control) after the 60 min group, and 176+/-43 (NS-7) and 223+/-38 mm(3) (control) after the 120 min group. Cortices in NS-7-treated groups were significantly less infarcted than in control groups at all treatment times. There was no significant difference in the striatal infarction volume between the treatment and control groups. Neurological examination showed that hemiparesis and abnormal posture of the NS-7 groups were significantly more improved at 48 h reperfusion than those of the control groups without posture examination in the 120 min group. These observations suggest that NS-7 may be a new potential therapeutic agent for the acute phase of cerebral infarction.
    Brain Research 05/2003; 969(1-2):168-74. · 2.73 Impact Factor
  • Article: Carotid hemodynamic parameters are useful for discriminating between atherothrombotic infarction and lacunar infarction.
    [show abstract] [hide abstract]
    ABSTRACT: Using ultrasound, we investigated whether carotid parameters differed among subtypes of ischemic stroke and evaluated the usefulness of these parameters in discriminating among subtypes. Patients with ischemic stroke admitted to Nippon Medical School Hospital were consecutively recruited and grouped into 3 subtypes based on the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification: cardioembolism (group CE), large-artery atherosclerosis (group LAA), and small-vessel occlusion (group SVO). All subjects underwent carotid ultrasonography to determine maximum intima-media thickness (IMT), maximum systolic velocity (Vmax), minimum diastolic velocity (Vmin), mean velocity, and pulsatility index (PI). Carotid parameters that differed among subtypes were statistically identified. A total of 138 patients were enrolled. Intergroup comparisons revealed that the Vmin of the affected side was significantly lower in group LAA than in group SVO (mean±SD, 0.12±0.05 m/s vs 0.15±0.05 m/s; P=.02) and the Vmin of the mean of both sides was lower in group LAA than in group SVO (0.12±0.04 vs 0.16±0.05; P=.03). Multivariate analysis showed that the PI of the affected side was a useful adjunct to discriminate between groups SVO and LAA (odds ratio=2.94; P=.03, group SVO as control). Receiver operating characteristic curve analysis found that the Vmin of the affected side was the most useful parameter for discriminating between group SVO and group LAA. The PI and the Vmin of the affected side were found to differ among stroke subtypes, and thus these may be useful parameters for discriminating among ischemic stroke subtypes.
    Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association 19(6):441-9.
  • Article: Stroke protection by atorvastatin treatment in stroke-prone spontaneously hypertensive rats (SHRSPs): 2. Measurement of regional cerebral blood flow (RCBF) by autoradiography