Shimon Amemiya

Nippon Medical School, Sendai, Kagoshima-ken, Japan

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Publications (15)36.55 Total impact

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    ABSTRACT: Poststroke depression is one of the most frequent and important complications of stroke. Although many studies of depression after stroke have been reported, clinical association between the risk of depression after stroke and the lesion location remains unclear. The presence of depression after stroke reportedly confers a poor prognosis; however, early recognition of depressive symptoms may improve outcomes. We examined the relation between lesion location and presence of depressive symptoms 1 month after ischemic stroke, with a view toward early management of depressive symptoms. In all, 134 consecutive patients with ischemic stroke were followed up to determine whether depression was present 1 month after stroke onset. Depressive symptoms were assessed by means of the Zung Self-rating Depression Scale. The lesion location was determined on magnetic resonance or computed tomography images. The incidence of depressive symptoms 1 month after stroke onset was 34.3%. Backward stepwise logistic regression analysis showed hypertension, education, and the presence of a left lenticulocapsular infarct, in particular, to be independent predictors of depressive symptoms. Patients with ischemic stroke, particularly in the left lenticulocapsular area, should be carefully evaluated for early detection and treatment of depressive symptoms, which may greatly influence outcome.
    Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association 05/2010; 19(3):184-9.
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    ABSTRACT: Neuromyelitis optica (NMO) is considered a distinct disease from multiple sclerosis (MS) because of its pathogenesis. It is well accepted that NMO selectively affects the spinal cord and optic nerve and is not associated with brain lesions at the onset of the disease, unlike MS. We present a unique case where the patient's initial lesion was in the brain, and optic neuritis and myelitis were revealed 6 years after the brain lesion. In addition, the patient's serum antiaquaporin 4 (AQP4) antibody was positive. We consider the brain lesion to precede abnormal lesion of NMO, and the AQP4 measurement is important for diagnostics, even if it occurs with brain lesions.
    Journal of neuroimaging: official journal of the American Society of Neuroimaging 09/2008; 19(3):263-5. · 3.36 Impact Factor
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    ABSTRACT: (123)I-iomazenil SPECT is of value in determining an epileptogenic focus, however, transient uptake change has been rarely reported in epileptic disorders. A 78-year-old woman diagnosed as status epilepticus (SE) showed transient reduction in (123)I-iomazenil uptake within the epileptic foci on SPECT images during a couple of weeks. It suggests a seizure-related 'short-term' plasticity in the central benzodiazepine receptors and dynamic change in the regulatory mechanisms of inhibitory neurotransmitter system within the epileptic foci in patients with SE.
    Acta Neurologica Scandinavica 05/2008; 117(4):285-8. · 2.47 Impact Factor
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    ABSTRACT: Pretreatment with a low dose of 3-nitropropionic acid (3-NPA) has been shown to induce ischemic tolerance in the gerbil hippocampus. It is well known that sublethal (2-min) ischemia also induces ischemic tolerance. To investigate the acquisition of ischemic tolerance with 3-NPA, we examined the protein expression after 3-NPA treatment in comparison with sublethal ischemia. Immunohistochemical studies revealed intense expression of Bcl-2 and Bcl-xL in the hippocampal CA1 area after 3-NPA treatment. Furthermore, the time course of the expression of Bcl-xL showed a similar pattern to the acquisition of ischemic tolerance by 3-NPA treatment. The induction of Bcl-xL occurred in the hippocampal CA1 area at 24 h after 3-NPA treatment, and significant induction was observed at 48 h. Western blot analysis of hippocampus harvested 48 h after the pretreatment, showed that the expression of Bcl-2 and Bcl-xL was significantly increased by either 3-NPA treatment or 2-min ischemia. However, PMCA1 and HSP70 protein expression increased only in the sublethal ischemia treated group. The difference between 3-NPA treated group and control group was not statistically significant. These results suggest that Bcl-2 and Bcl-xL are essential for acquisition of ischemic tolerance, while HSP70 and PMCA1 play important roles in the enhancement of ischemic tolerance.
    Life Sciences 11/2005; 77(23):2867-78. · 2.56 Impact Factor
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    ABSTRACT: To investigate the effect of an antioxidant edaravone on the apoptotic process, we examined Bax and Bcl-2 immunohistochemical expression and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) reactivity. Rat focal ischemia models were prepared by 2 h transient middle cerebral artery occlusion. Edaravone or physiological saline was intravenously administered after reperfusion. After 24 h of reperfusion, infarction volume assessments, Bax and Bcl-2 immunohistochemistry and TUNEL staining were performed as well as neurological evaluation. Cortical cerebral blood flow was not statistically different between the treatment-groups. Edaravone-treated animals showed significantly improved neurological outcome. Total and cortical infarct volumes in the edaravone group significantly decreased. In addition, edaravone-treatment provided a significant reduction in the number of TUNEL-positive apoptotic cells, a decrease in Bax immunoreactivity and an increase in Bcl-2 expression within the peri-infarct area. Edaravone shows an excellent neuroprotective effect against ischemia/reperfusion brain injury through a Bax/Bcl-2 dependent anti-apoptotic mechanism.
    European Journal of Pharmacology 07/2005; 516(2):125-30. · 2.59 Impact Factor
  • Journal of Cerebral Blood Flow & Metabolism 01/2005; 25. · 5.40 Impact Factor
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    ABSTRACT: Most reports of micrographia associated with focal brain lesions have related this finding to damage in the left basal ganglia. Here we describe the case of a 68-year-old man presenting with reversible micrographia accompanied by hypophonia in the absence of extrapyramidal signs after cerebral infarction in the left subcortical region. At the time of the patient's admission, diffusion-weighted magnetic resonance imaging sequence showed the lesion to principally involve the corona radiata, with some involvement of the putamen. Neurologically, mild right-sided brachiofacial hemiparesis and grasp reflexes - a frontal lobe sign - were observed. As his micrographia and hypophonia improved, the patient's grasp reflexes improved in parallel. In addition, recovery of regional cerebral blood flow in the left frontal lobe was confirmed by single photon emission computed tomography (technetium-99 m HMPAO). The present case suggests the possibility that the function of frontal-subcortical circuit might also be involved in the production and improvement of micrographia and that micrographia and hypophonia may share a common pathophysiology.
    European Journal of Neurology 10/2003; 10(5):593-6. · 4.16 Impact Factor
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    ABSTRACT: Reversible posterior leukoencephalopathy syndrome is one of the most serious complications of immunosuppressive therapy. The clinical features include headache, altered mental functioning, seizures, cortical blindness and other visual disturbances, with hypertension. The neuroimaging studies reveal predominant posterior leukoencephalopathy. Usually, antihypertensive therapy and reduction or withdrawal of immunosuppressive agents have been reported to resolve the neurological deficits and imaging abnormalities within a few weeks. We discuss here a 51-year-old woman with nephrotic syndrome who developed acute leukoencephalopathy during combination therapy with prednisolone and cyclosporine. She developed severe headache, visual disturbance, consciousness disturbance, and generalized tonic clonic convulsion. A computed tomography scan (CT) revealed low-density areas in the subcortices of the parietal and occipital lobes. Magnetic resonance imaging (MRI) disclosed a high signal intensity area on T2-weighted images and a low signal intensity area on T1-weighted images in the same lesions. Follow-up brain CT and MRI were performed several times. Three weeks after the first study, these lesions had completely resolved, but she had persistent altered consciousness for more than 1 year.
    Clinical and Experimental Nephrology 04/2003; 7(1):63-6. · 1.25 Impact Factor
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    ABSTRACT: Edaravone, a novel free radical scavenger, has been reported to reduce ischemic damage in rats subjected to transient focal ischemia. The aim of this study is, therefore, to investigate the effect of a combined therapy with edaravone and mild hypothermia of 35 degrees C. Sprague-Dawley rats were subjected to MCA occluding an intraluminal suture technique for 2 hrs. The rats were reperfused for 24 h and decapitated for infarct and edema analysis. Animals were randomly devided into four groups: (I) vehicle + normothermia (control) (II) vehicle + mild hypothermia (III) Edaravone + normothermia (IV) Edaravone + mild hypothermia. Mild hypothermia alone had no reduction of the brain damage. The edaravone alone significantly reduced edema volume. The combined treatment with edaravone and mild hypothermia reduced both infarct and edema volume. In addition, this treatment provided for the best functional outcome. These results demonstrate that free radical scavenger, edaravone attenuates brain edema and that the combined therapy with edaravone and mild hypothermia significantly reduces not only edema but also infarct on transient focal cerebral ischemia in rats. The neuroprotective effects seen in this study may be due to the combined interaction of antiedema activity between edaravone and mild hypothermia, suppressing free radical production.
    Acta neurochirurgica. Supplement 02/2003; 86:199-203.
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    ABSTRACT: To evaluate the feasibility of utilizing cerebral blood flow (CBF) index images, we attempted to investigate 1) whether CBF index images can reveal the resulting infracted area, 2) whether the CBF index can correlate other modality (SPECT). DWI and DPI were obtained in 17 patients within 12 hours of stroke onset and follow up MRI. On three DPI delivered images, namely relative regional cerebral blood volume (rrCBV), uncorrected mean transit time (MTTu) and CBF index images, correlations between initial lesion volume of and follow up infarction volume of three images and rCBF images delivered with singular value decomposition (SVD) methods were assessed. Then 99mTc-ECD SPECT was taken immediately after MRI to correlate to MRI data. Among the three images, lesion volume of CBF index images against follow up infarct volume had the highest correlation (r = 0.995) to a linear fit and the slope was closest to 1.0 (0.91) and had identical accuracy to the regression coefficient of rCBF images. CBF index well correlated to SPECT delivered CBF. CBF index images can accurately predict final infarct volume. Evaluating CBF index images together with DWI can guide the initial assessment in the acute stage of cerebral ischemia.
    Acta neurochirurgica. Supplement 02/2003; 86:241-6.
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    ABSTRACT: The aim of this study is to determine whether a selective thrombin inhibitor, Argatroban, would prevent neuronal cell death and whether extra-mild hypothermia (35 degrees C) would enhance the neuroprotective effect of a selective thrombin inhibitor following transient focal ischemia in rats. Sprague-Dawley rats were subjected to MCAo using an intraluminal suture technique for 2 hrs. The rats were reperfused for 24 h and decapitated for infarct and edema analysis. Argatroban-treated animals received a continuous injection of argatroban (3.0 mg/kg) for 24 hrs after onset of ischemia, while vehicle-treated groups received same dose of vehicle. During ischemia, temporal muscle and rectal temperatures were monitored and maintained at 37 degrees C in the normothermic animals and at 35 degrees C in the hypothermic animals. Argatroban ameliorated the cortical ischemic damage significantly (p < 0.05). Moreover, argatroban with mild hypothermia decreased the cortical infarct or edema volume significantly compared with those of groups I and III (p < 0.05). Argatroban improved neurological symptoms significantly and also improved survival rate. These results demonstrate that extra-mild hypothermia (35 degrees C) enhances neuroprotective effects of a selective thrombin inhibitor, argatroban, suggesting that this combined therapy may be a new therapeutic strategy for the treatment of acute stroke.
    Acta neurochirurgica. Supplement 01/2003; 86:195-8.
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    ABSTRACT: To evaluate the feasibility of utilizing cerebral blood flow (CBF) index images, calculated automatically and quickly from dynamic perfusion imaging (DPI), to identify acute cerebral ischemia. We attempted to investigate (1) whether the CBF index has a threshold for assessing tissue outcome, (2) whether CBF index images can predict the resulting infracted area, and if so, (3) whether the predictive capacity of the CBF index image is comparable to the regional CBF (rCBF) image delivered from singular value decomposition (SVD) deconvolution methods, which are regarded as most accurate in predicting the final infarct area. Diffusion-weighted images (DWI) and DPI were obtained in 17 patients within 12 hours of stroke onset and follow-up magnetic resonance imaging (MRI). On 3 DPI-delivered images, namely relative regional cerebral blood volume (rrCBV), uncorrected mean transit time (MTTu) and CBF index images, univariate discriminant analysis was done to estimate cut-off values to discriminate between infarcted and noninfarcted areas. Subsequently, correlations between the initial lesion volume of 3 images together with rCBF images delivered with SVD methods and the final infarct volume on follow-up T2-weighted MRI taken at the 8th to 20th day were determined. Among the 3 images, only the CBF index image was able reveal the threshold of the ischemic region. Lesion volume of CBF index images against follow-up infarct volume had the highest correlation (r = 0.995) to a linear fit and the slope was closest to 1.0 (0.91) among the 3 and had identical accuracy to the regression coefficient of rCBF images. CBF index images can predict final infarct volume. Evaluating CBF index images together with DWI can guide the initial assessment in the acute stage of cerebral ischemia.
    Journal of Computer Assisted Tomography 01/2003; 27(6):874-81. · 1.58 Impact Factor
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    ABSTRACT: 3-Methyl-1-phenyl-pyrazolin-5-one (edaravone), a novel free radical scavenger, has been reported to reduce ischemic damage in rats subjected to transient focal ischemia. The aim of this study is, therefore, to investigate the effect of a combined therapy with edaravone and mild hypothermia at 35 °C. Sprague–Dawley rats were subjected to middle cerebral artery (MCA) occluding using by an intraluminal suture technique for 2 h. The rats were reperfused for 24 h and decapitated for infarct and edema analysis. Animals were randomly divided into four groups: (I) vehicle+normothermia (control); (II) vehicle+mild hypothermia; (III) edaravone+normothermia; (IV) edaravone+mild hypothermia. Mild hypothermia alone had no reduction of the brain damage. The edaravone alone significantly reduced edema volume. The combined treatment with edaravone and mild hypothermia reduced both infarct and edema volume. In addition, this treatment provided for the best functional outcome. These results demonstrate that a free radical scavenger, edaravone, attenuates brain edema and that the combined therapy with edaravone and mild hypothermia significantly reduces not only edema but also infarct on transient focal cerebral ischemia in rats. The neuroprotective effects seen in this study may be due to the combined interaction of antiedema activity between edaravone and mild hypothermia, suppressing free radical production.
    International Congress Series 01/2003; 1252:109–115.
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    ABSTRACT: The object was to assess alterations in CSF concentrations of monoamine metabolites during withdrawal of medication in patients with Parkinson's disease in relation to the presence or absence of episodes resembling neuroleptic malignant syndrome (NMS). This syndrome is a fatal condition developing after neuroleptic therapy, and a neuroleptic malignant-like syndrome (NMLS) may also occur after withdrawal of antiparkinsonian drugs in patients with Parkinson's disease. Previous biochemical assays showed that the CSF concentration of the dopamine metabolite homovanillic acid (HVA) is an independent prognostic factor for development of NMLS in patients with Parkinson's disease. In the present study, CSF concentrations of HVA, the noradrenaline (norepinephrine) metabolite 3-methoxy-4-hydroxyphenylethylene glycol, and the serotonin metabolite 5-hydroxyindole acetic acid were assayed using high performance liquid chromatography with electrochemical detection. The study population consisted of nine patients with Parkinson's disease with NMLS and 12 without NMLS, in whom metabolites were assayed during both withdrawal and remedicated periods. Concentrations of HVA in the CSF were significantly lower during the withdrawal period than the medicated period regardless of whether patients developed NMLS, and HVA concentrations were comparably increased after remedication in both groups. However, HVA concentrations were significantly lower in patients with NMLS than in those without NMLS during both withdrawal and medicated periods. Other metabolites showed no significant differences. The present data provide further biochemical evidence for extremely suppressed central dopaminergic activity during NMLS, which may indicate a narrow safety margin for medication withdrawal in patients with Parkinson's disease.
    Journal of Neurology Neurosurgery &amp Psychiatry 08/2001; 71(1):111-3. · 4.92 Impact Factor
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    Neurology 09/2000; 55(4):600-1. · 8.25 Impact Factor

Publication Stats

129 Citations
36.55 Total Impact Points

Institutions

  • 2003–2010
    • Nippon Medical School
      • • Department of Internal Medicine
      • • Second Department of Internal Medicine
      Sendai, Kagoshima-ken, Japan
  • 2008
    • Kanazawa Medical University
      Kanazawa, Ishikawa, Japan
  • 2000–2001
    • Tokyo Metropolitan Geriatric Medical Center
      Edo, Tōkyō, Japan