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Biomedical subjects

Michiyasu Suzuki

Publications and source records attributed to Michiyasu Suzuki.

At least 19 recordsLinked to original sources
PubMed2006

Cilostazol inhibits the redistribution of the actin cytoskeleton and junctional proteins on the blood-brain barrier under hypoxia/reoxygenation.

Cilostazol is a selective inhibitor of cyclic nucleotide phosphodiesterase 3 (PDE3), which induces a vasodilatoric antiplatelet effect. In the present study, we investigated the impact of cilostazol on the blood-brain barrier (BBB), while focusing on the actin cytoskeleton (F-actin), the permeability of endothelial cells, and the junctional proteins under hypoxia/reoxygenation (H/R). Cilostazol was thus found to inhibit the cytoskeletal reorganization under H/R, in which F-actin decrease at the cell periphery. Accordingly, cilostazol was able to attenuate the hyperpermeability of endothelial cells in H/R to the level of the permeability in normoxia. However, the adherens junction (AJ) protein VE-cadherin was not preserved in the presence of cilostazol under H/R. On the other hand, beta-catenin was slightly retained by cilostazol. In contrast to the redistribution of these proteins, immunoblotting demonstrated the total amount of AJ and tight junction (TJ) proteins (occludin, ZO-1 and ZO-2) to not show any significant change under H/R stress in either the presence or absence of cilostazol. Taken together, cilostazol potently displayed a protective effect against acute ischemia by preventing an increase in the endothelial permeability through the preservation of the actin cytoskeleton and the redistribution of junctional proteins.

Actins↗
PubMed2006

Surgery for spontaneous intracerebral hemorrhage has greater remedial value than conservative therapy.

BACKGROUND: The aim of this study was to compare the efficacy of surgery for spontaneous intracerebral hemorrhage with that of medical treatment, based on data from the Japan Stroke Registry Study. METHODS: From 1999 to 2001, 1010 patients with spontaneous intracerebral hemorrhage were registered in the Japan Standard Stroke Registry Study from 45 stroke center hospitals in Japan. The National Institutes of Health Stroke Scale (NIHSS), Japan Stroke Scale (JSS), and modified Rankin Scale scores were used to compare severity and improvement in patients given surgical and medical treatment. CONCLUSIONS: Surgically treated patients, especially those with cerebellar hemorrhage, had significantly greater improvement in NIHSS or JSS score compared with medically treated patients. Our findings indicated that the patients who underwent surgery appeared to have better outcomes. But, because the study was not randomized, this observation cannot be interpreted as indicating that surgery is advantageous.

Adult↗
PubMed2006

Various magnetic resonance imaging patterns of chronic subdural hematomas: indicators of the pathogenesis?

Magnetic resonance (MR) imaging can detect various patterns in chronic subdural hematomas. These patterns were compared to the computed tomography (CT) appearances and chemical analysis of the content in 60 hematomas from 44 patients. The hematomas could be classified into five types on both T(1)- and T(2)-weighted images: low, high, and mixed intensity, isointensity, and layered. Combining the T(1)- and T(2)-weighted images of all 60 hematomas revealed a total of 14 different imaging patterns. Combining the CT and MR imaging findings of 55 hematomas identified 25 different patterns. Analysis of the hematoma contents showed that hemolysis-related parameters, such as potassium, glutamate oxaloacetate transaminase, bilirubin, lactate dehydrogenase, and protein concentration, were markedly higher than in the peripheral blood, and there were significant correlations between these parameters. Mixed intensity hematomas were significantly thicker than the other types, and showed markedly higher values of hemolysis-related parameters. Factors affecting the CT and MR imaging findings, such as fresh bleeding, hemolysis, and hemoglobin changes, coexist in a hematoma to varying degrees, and these factors may interact with the age of the hematoma to produce the different patterns that are observed.

Adolescent↗
PubMed2006

Use of a Peltier chip with a newly devised local brain-cooling system for neocortical seizures in the rat. Technical note.

Local cortical cooling for termination of epileptic discharges (EDs) has recently become a focus of research. The authors report on a newly devised cooling system that uses a thermoelectric (Peltier) chip and examine the system's performance in experimental neocortical seizures. Experiments were performed in adult male Sprague-Dawley rats after induction of halothane anesthesia. The Peltier chip was attached to a heat sink with a water channel. Two silicon tubes were connected to the heat sink, and water at 37 degrees C was circulated in the channel. The newly designed device was placed on the surface of the cortex. Kainic acid (KA) was injected into the cortex to provoke EDs. In the nonepileptic cortex, the temperature of the cortical surface decreased to 14.8 +/- 1.5 degrees C and that 2 mm below the surface to 27.1 +/- 3.1 degrees C within 30 seconds after the start of cooling. The temperature of the heated side of the chip was maintained at approximately 36.9 degrees C. Without water circulation, the temperature of the cortical surface decreased to 20 degrees C but soon began to increase, peaking at 30 degrees C. The temperature of the heated side of the chip rose to more than 60 degrees C. The EDs, which appeared within 20 minutes after KA injection, began to decrease in amplitude immediately after cooling began and continued to decrease as the temperature of the cortex was lowered. Sufficient miniaturization and good performance of the cooling device was demonstrated. Further efforts to develop implantable cooling systems and improve existing ones should be continued.

Animals↗
PubMed2005

Improvement of functional outcome after radical surgery in glioblastoma patients: the efficacy of a navigation-guided fence-post procedure and neurophysiological monitoring.

This retrospective study investigated the functional outcomes of patient with glioblastoma receiving radical surgery before and after the adoption of the navigation-guided fence-post (NGFP) procedure and neurophysiological monitoring. We investigated 42 glioblastoma patients receiving radical surgery in our institute between 1980 and 2005. Of the 42 patients, 18 patients from 1980 to 1996 (1st term) underwent radical surgery without navigation system guidance, NGFP, or neurophysiological monitoring; 11 patients from 1997 to 2002 (2nd term) underwent surgery with simple navigation system guidance but without NGFP procedure or neurophysiological monitoring, and 13 patients from 2003 to 2005 (3rd term) underwent surgery with the NGFP procedure and neurophysiological monitoring as appropriate. There were no significance differences between any of the three term groups in age, gender, preoperative KPS score, or 'surgical staging for glioma' according to the difficulty of surgery. The rates of 95% or greater volume reduction in each term were 38.9%, 54.5% and 76.9%. The rates of morbidity were 38.9%, 18.1% and 0%. The change in KPS scores (delta KPS) before and after the perioperative period in each term were -16.1 +/- 6.6 SEM, -9.0 +/- 5.8 SEM and +8.5 +/- 3.7 SEM, respectively. The delta KPS in the 3rd term was significantly better than those of 1st and 2nd terms (P < 0.01, Kruskal-Wallis rank test). The rate of patients who were discharged to home and who resumed daily useful life without assistance was 38.9%, 63.6% and 84.6% in each term, respectively. The mean survival times in each term were 9.9, 14.0 and 16.8 months. The introduction of the NGFP procedure and neurophysiological monitoring in glioblastoma radical surgery improved the functional outcome of patients.

Brain Neoplasms↗
PubMed2005

Association of intra- and extradural developmental venous anomalies, so-called venous angioma and sinus pericranii.

INTRODUCTION: We report a case of cerebellar venous angioma and parietal sinus pericranii. DISCUSSION: Venous angioma is classified as a developmental venous anomaly (DVA) because it is not a neoplasm but a variant that develops during embryogenesis. Sinus pericranii should be classified as extradural-type DVA. Although there have been few reports of association between these conditions, both are suspected to have the same pathogenesis, i.e., transient venous hypertension in the late embryonic period influencing venous development.

Central Nervous System Venous Angioma↗
PubMed2005

Chlamydia pneumoniae infection as a risk factor for subarachnoid hemorrhage.

Many risk factors for subarachnoid hemorrhage (SAH), such as hypertension and recent infection, have already been established. Chlamydia pneumoniae is a common respiratory pathogen that has been implicated as a potential risk factor for hypertension and atherosclerotic diseases. The purpose of the case-control study presented here was to examine the causative relationship between C. pneumoniae infection and SAH. Serum C. pneumoniae IgG and IgA antibodies were measured using an enzyme-linked immunosorbent assay in 52 patients with SAH and in 104 healthy age-matched control subjects. Multivariate analysis revealed a significant association between SAH and both a strong seropositivity for IgG and/or IgA antibodies against C. pneumoniae (odds ratio, OR, 3.62; 95% confidence intervals, CI, 1.06-12.39; p = 0.040), which indicates the presence of acute C. pneumoniae infection, and hypertension (OR, 2.91; 95% CI, 1.42-5.96; p = 0.0035). These results provide evidence that infection with C. pneumoniae may be a risk factor for SAH from a ruptured intracranial aneurysm.

Adult↗
PubMed2005

Systemic administration of argatroban reduces secondary brain damage in a rat model of intracerebral hemorrhage: histopathological assessment.

This study investigated the effects of argatroban, a thrombin inhibitor, on brain edema and inflammation in a rat intracerebral hemorrhage (ICH) model. ICH was induced by injecting collagenase IV into the right caudate nucleus. Argatroban was administered intraperitoneally. Argatroban reduced brain edema from 44.6 to 14.3 microl at 72 h. Infiltration of polymorphonuclear leukocytes at 24 h and monocyte/macrophage at 24 and 72 h was significantly suppressed by argatroban. Argatroban did not increase the volume of hematoma. Systemic administration of argatroban reduced secondary brain damage including edema and inflammation in a rat ICH model.

Animals↗
PubMed2005

Spinal cord infarction demonstrated by diffusion-weighted magnetic resonance imaging.

Spinal cord infarction is a rare entity of varying etiology although most often associated with atherosclerotic aortic disease. Definitive diagnosis of (idiopathic) spinal cord infarction in the acute stage and in the absence of demonstrable predisposing factors is not always possible even with MRI. Diffusion-weighted MRI (dwMRI) may provide valuable information in the evaluation of spinal cord ischemia. A 45-year-old woman presented with idiopathic spinal cord infarction manifesting as sudden onset of paraparesis and sphincter dysfunction. Both T2-weighted and line-scan dwMRI revealed hyperintense signals in the dorsal part of the spinal conus. Apparent diffusion coefficient values were significantly low in the lesion, suggesting cytotoxic edema compatible with acute ischemia. The clinical course and other radiographic findings were also compatible with idiopathic spinal cord infarction. Diffusion-weighted MRI is an important diagnostic tool for examining patients with suspected spinal cord ischemia.

Diffusion Magnetic Resonance Imaging↗
PubMed2005

Vascular reconstruction using interposition of saphenous vein graft for symptomatic stenosis at the extradural-intradural junction of the vertebral artery. Case report.

BACKGROUND: Symptomatic, medically refractory vertebrobasilar stenosis carries a poor prognosis and is an indication for vascular reconstruction. CASE PRESENTATION: A 67-year-old man suffered medically refractory recurrent vertigo due to artery-to-artery embolism caused by long, eccentric, and severe stenosis at the extradural-intradural junction of the right vertebral artery. Transluminal angioplasty was deferred because of the occurrence of critical brain ischemia during temporary balloon occlusion. After an occipital artery to posterior inferior cerebellar artery bypass, the vascular lesion in the right vertebral artery was resected and was reconstructed with interposition of a saphenous vein graft. The postoperative course was uneventful, and the patient did not experience further symptoms. Postoperative angiography revealed a widely patent right vertebral artery. CONCLUSION: This surgical procedure is useful for the vascular reconstruction of symptomatic stenosis at the extradural-intradural junction of the vertebral artery when transluminal angioplasty is contraindicated and when bypass surgery is not sufficient.

Aged↗
PubMed2005

Effect of cell phone magnetic fields on adjustable cerebrospinal fluid shunt valves.

The rapid increase in the number of cell phone users has led to the suggestion that electromagnetic waves might affect medical devices. Cerebrospinal fluid shunt valves contain a magnetic device to allow the intracranial pressure setting to be adjusted transcutaneously. Among the valves tested, the settings of the Strata valve, the Hakim valve, and the Sophy valve were affected by magnetic flux densities of 6.0, 17.5, and, 40.0 mT, respectively. Cell phones produce a magnetic flux density of 3.0 to 40.0 mT. Although cell phones could theoretically influence shunt valves, this seems unlikely because the flux density decreases with the square of the distance.

Cell Phone↗
PubMed2005

Recurrence and extension of lobar hemorrhage related to cerebral amyloid angiopathy: multivariate analysis of clinical risk factors.

BACKGROUND: Many recent studies have analyzed clinical risk factors for the recurrence and extension of intracerebral hemorrhage. However, they have not been investigated in patients with lobar hemorrhage related to cerebral amyloid angiopathy (CAA). METHODS: We studied 40 surgically treated patients with lobar hemorrhage diagnosed histologically as being related to CAA. To determine clinical factors influencing the recurrence and hematoma size their clinical data (demographics, medical history, and radiographic and laboratory data) were examined retrospectively and subjected to multivariate analysis. RESULTS: Twelve patients (30%) had recurrent lobar hemorrhage. Twenty-one patients had a small hematoma and 19 had a large hematoma. Hypertension was the only significant clinical factor influencing the recurrence of CAA-related lobar hemorrhage. There was no significant clinical factor influencing the hematoma size of CAA-related lobar hemorrhage. CONCLUSIONS: The history of hypertension is associated with an increase in the recurrence of CAA-related lobar hemorrhage.

Aged↗
PubMed2005

Management of patients with cavernous angiomas presenting epileptic seizures.

BACKGROUND: The aim of this study was to establish a treatment strategy for patients with cavernous angiomas and have seizures. METHODS: We analyzed retrospectively 31 patients with cavernous angiomas presenting with seizures. Of the 31 patients, 15 (11 men, 4 women) had been treated medically (the medical group) and 16 (11 men, 5 women) had been treated surgically (the surgical group). The percentage of patients who became seizure-free and the number of anticonvulsants used were compared between these 2 groups. The mean follow-up period was 5.3 years (range, 7 months-10 years). There was no statistically significant difference between the 2 groups with regard to the number of patients, sex, age, and follow-up period. RESULTS: The percentage of patients who became seizure-free was higher in the surgical group than in the medical group (80% vs 19%, P < .01). The number of anticonvulsants required was reduced in the surgical group after surgery (from 1.5 +/- 0.7 to 1.1 +/- 0.8, P < .01) and was not reduced after in the medical group. CONCLUSIONS: Surgical intervention may have greater benefits than medical intervention for patients with cavernous angiomas presenting with epileptic seizures.

Adult↗
PubMed2005

Multiple aneurysms arising from the posterior inferior cerebellar artery with unknown etiology--case report--.

A 67-year-old man presented with multiple aneurysms arising from the caudal loop of the posterior inferior cerebellar artery (PICA), possibly as a result of blunt trauma. Computed tomography of the head revealed subarachnoid hemorrhage in the posterior fossa and sylvian fissure. Repeated angiography demonstrated an aneurysmal dilatation and an irregular wall on the caudal loop of the PICA. Under the operating microscope, two lesions were observed 10 mm distal to the apex of the caudal loop, both consisting of a tiny hole on the vessel wall with a fragile fringe of connective tissue and covered with a firm clot. The height of the lesions corresponded to the C-l lamina, so the lesions were probably traumatic rather than saccular.

Aged↗