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Y Yonemasu

Publications and source records attributed to Y Yonemasu.

At least 55 records · Page 3Linked to original sources
PubMed1993

Experimental seizure-induced brain damage: electrophysiological, metabolic and pathological correlation.

Limbic seizures elicited by an intra-amygdaloid KA injection is the only and unique model which can produce unilateral hippocampal degenerative lesions and atrophy. This model is important not only to investigate neurophysiological epileptogenesis but also to study the causative process of human mesial temporal sclerosis observed in patients with intractable complex partial seizure.

Amygdala↗
PubMed1993

Magnetic resonance imaging in kainic acid-induced limbic seizure status in cats.

Magnetic resonance imaging before, during, and after kainic acid (KA)-induced limbic seizure status in cats demonstrated the bilateral hippocampi as slightly high-intensity areas on the T2-weighted images during the limbic seizure status, and isointensity areas 1-2 weeks after KA injection when the limbic seizure status subsided. However, the hippocampi again became high-intense 1-3 months after KA injection. Histological study suggested that the high-intensity area during the limbic seizure status resulted from regional edema, and in the chronic period from marked gliosis and/or atrophic change as a consequence of tissue damage in the hippocampus.

Amygdala↗
PubMed1993

Pathology of infantile brain tumor.

Five brain tumors in infancy were studied histopathologically. Though four of them could be included in primitive neuroectodermal tumor, histopathological findings were diverse. The diagnoses were medulloblastoma, cerebellar neuroblastoma, pineoblastoma, ependymoblastoma and ependymoma. While conventional stain for microscopy exhibited their specific findings, immunohistochemical and electron microscopical studies revealed morphological findings related functional structures of the tumor cells. These methodology is mandatory in order to elucidate cytogenesis and differentiation of infantile brain tumors.

Brain Neoplasms↗
PubMed1993

[Effect of intracarotid injection of neuropeptide Y (NPY) on cerebral blood flow in rats and possible application of NPY to the selective drug chemotherapy for brain tumor].

Neuropeptide Y (NPY) was continuously administered to Wistar rats in the normal and glioma bearing conditions intracarotidly via the external carotid artery and local cerebral blood flow (LCBF) was measured by a [14C] iodoantipyrine technique. In the normal rats, the LCBF at the injecting side of NPY markedly reduced in 2 minutes after beginning of drug administration. In glioma-bearing rats, LCBF in the cerebral cortex and caudate nucleus reduced to the same level as normal rats. However reduction of LCBF in the tumor was not significantly different from that of ipsilateral cortex and caudate nucleus. The results of this study suggest that flow moduration by NPY injection increases delivery of intra-carotid administered anticancer drugs to the brain tumor with concomitant decrease of neurotoxicity to the normal brain.

Animals↗
PubMed1993

[Epileptogenicity and neurotoxicity induced by intra-amygdaloid injection of various excitatory amino acids in rats].

The electroencephalographic and histopathological changes following intra-amygdaloid injection of excitatory amino acids were examined in rats. Limbic seizure status was induced after injection of kainic acid (KA), domoic acid (DA), quisqualic acid (QA), alpha-allo-kainic acid (ALLO-KA) and D-glutamic acid (D-GA). The excitatory effect was found to be in the following order: KA > DA >> QA > ALLO-KA >> D-GA. D-GA caused only a transient paroxysmal discharge on EEG. However, seizure was not induced by an injection of L-glutamic acid (L-GA), D-aspartic acid (D-AA) and L-aspartic acid (L-AA). The minimum epileptogenic doses of these amino acids were defined and intra-amygdaloid injection of these doses were performed. Seven days following the injections, histopathological study was performed. These injection resulted in various degree of degeneration and neuronal cell loss of the pyramidal cells in the ipsilateral hippocampus in the following order of severity: DA > or = KA > D-GA > ALLO-KA > QA. These results indicate absence of correlation between epileptogenicity and histopathological changes. Non epileptogenic amino acids induced no pathological changes of hippocampus or the injected site. These results suggest that the severity of hippocampal damage induced by intra-amygdaloid injection of amino acids depends not only on the magnitude of the induced limbic seizure status but also on the difference of neuropharmacological properties of those amino acids in terms of the interaction with their receptors. Further studies are necessary to elucidate the mechanism of actions of these excitatory amino acids in relation to their receptor subtypes.

Amino Acids↗
PubMed1993

[Surgical removal of lateral pontine cavernous angioma: review of the surgically treated cases in the literature].

A case of cavernous angioma of the pons which was surgically and successfully excised was reported. A 36 year-old man complained of progressive headache, double vision and tinnitus. Neurologic examination revealed left fifth, sixth and seventh cranial nerve palsies. He had left limb ataxia and right sided hemisensory deficit. A computed tomographic (CT) scan on admission disclosed a hematoma in the left lateral portion of the pons. Serial CT scans demonstrated progressive increase of hematoma. MRI scans revealed an area of mixed signal intensity in T1 weighted images. These findings were thought to be consistent with a cavernous angioma. Three months after the onset, surgery was performed using a lateral suboccipital approach. Histological examination disclosed cavernous angioma. After surgery, the patient's neurological deficits improved, and after 3 months, all symptoms except the mild limb ataxia had disappeared.

Brain↗
PubMed1993

[Markedly dilated cervical carotid arteries in a patient with a ruptured aneurysm of the anterior communicating artery: a case report].

We reported a case of ruptured aneurysm of the anterior communicating artery with marked dilatation of bilateral cervical carotid arteries. A 38 year old female suffered a subarachnoid hemorrhage. Angiography on admission revealed markedly dilated cervical carotid arteries with smooth lumen and a few segmental areas with mild constrictions in their entire course up to the carotid canals (their maximal sagittal diameters exceeded those of a cervical vertebral body). A saccular aneurysm was also seen at the junction of right A1, A2, and Acom. External carotid arteries were normal in size. Vertebral arteries were not examined because of failures of selective cannulation. The patient was operated upon and trapping of Acom was performed. During the operation, no definite arteriosclerotic changes were identified in the intracranial arteries. Histopathological examination of the surgical specimens revealed marked hyperplasia of the smooth muscle of the tunica media with intact internal elastic lamina both in a superficial temporal artery and a middle meningeal artery. During the operation, pneumothorax developed due to the rupture of bullae in the right lung. Past history of this patient disclosed hypertension noted a few years previously, and frequent severe bruises following minor trauma. Repeated angiography performed three months after the operation disclosed unchanged dilatation of the cervical carotid arteries as well as mild intraluminal irregularities in the proximal one third of the left renal artery. This patient died of pneumonia one year after the operation, but autopsy was not permitted. Possible diagnosis of this patient was discussed, with particular emphasis on fibromuscular dysplasia and Ehlers-Danlos type IV (arterial, ecchymotic, or Sack-Barabas type).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Effects of intracarotid infusion of neuropeptide Y on cerebral blood flow in rats.

Neuropeptide Y (NPY) was continuously administered to Wistar rats intracarotidly via the external carotid artery and local cerebral blood flow (LCBF) was measured by a quantitative autoradiography using [14C]iodoantipyrine. A remarkable reduction in LCBF was observed in the NPY infused hemisphere. This depression was irregular and was particularly evident in the hippocampus, selective thalamic nuclei and the cerebral cortex.

Animals↗
PubMed1992

Cerebral blood flow and histopathological changes following permanent bilateral carotid artery ligation in Wistar rats.

Cerebral blood flow and histopathological changes after bilateral carotid artery ligation (BCAL) in Wistar rats were studied. Eight of the 38 rats (21%) died within one week. In the 30 survivors, the incidence of histopathological change was 90% in the caudate nucleus, 23% in the cortex, 30% in the hippocampus, and 0% in the other structures. Local cerebral blood flow (LCBF) was measured using the quantitative autoradiographic 14C-iodoantipyrine technique in 24 anatomically discrete regions of the brain. BCAL induced ischemia in the entire forebrain. The percent reduction of LCBF was between 25-94% of the control at 2.5 h after BCAL. LCBF tended to recover 1 week after BCAL except for the regions of neuronal damage. These results suggest that neuronal damage does not correlate with the flow rate. In the present study, selective neuronal damage was also observed in rats with chronic cerebral ischemia.

Animals↗
PubMed1992

Kainic acid-induced thalamic seizure in cats--a possible model of petit mal seizure.

Bipolar depth electrodes were implanted stereotaxically in the thalamus, hippocampus and midbrain reticular formation of cats. Cortical screw electrodes were placed over the bilateral sensorimotor cortex. A guide cannula with an inner injection cannula was inserted unilaterally into the posterolateral ventral nuclei (VPL) of the thalamus. Eight days after the procedures, kainic acid (2.0 micrograms) was injected unilaterally into the VPL via the injection cannula in freely moving animals and electro-clinical observations were made. About 1 h after the kainic acid injection, multiple spikes were observed in the VPL (injection site), which propagated to the subcortical structures. These seizures finally propagated bilaterally to the cortex about 2 h after the injection. About 3-4 h after the injection, small spike and wave complexes repeatedly appeared for a short period of time in cortical leads and cats exhibited behavioral arrest with unresponsiveness during the seizures. About 24 h after the injection, generalized small spike and wave complexes were observed intermittently in cortical and subcortical structures. They persisted for 4-5 s and were associated with behavioral arrest and staring. The results demonstrate that a unilateral microinjection of kainic acid into VPL induced petit mal-like seizure, and suggest that VPL plays an important role in the generation or transfer of spike and wave complexes.

Animals↗
PubMed1992

The effects of oxiracetam (CT-848) on local cerebral glucose utilization after focal cerebral ischemia in rats.

The effects of oxiracetam on the reduction of brain metabolism induced by focal cerebral ischemia were investigated by measuring local cerebral glucose utilization (LCGU) in rats 24 hr after left middle cerebral artery occlusion. Focal cerebral ischemia reduced LCGU in the entire ipsilateral cortex, the greatest reduction being in the lateral parts of the frontoparietal cortex. LCGU was slightly reduced in the contralateral cortex; this reduction was considered to be caused by diaschisis. Oxiracetam was administered intraperitoneally for 3 days prior to middle cerebral artery occlusion. In the ipsilateral cortex, LCGU reduction was minimized in the ischemic center areas by oxiracetam at a dose of 400 mg/kg and in more extensive areas, by a dose of 800 mg/kg. Moreover, oxiracetam at a dose of 800 mg/kg enhanced metabolism impaired by diaschisis in the caudal areas of the contralateral cortex. These findings suggest that oxiracetam minimizes the reduction of brain function induced by ischemia and may therefore be useful in the treatment of cerebrovascular disease.

Animals↗
PubMed1992

Lipoma involving the skull. Case report.

The case of an intraosseous lipoma involving the left frontal bone is reported. Lipomas of the bone are rare; only three cases of lipomas involving the skull have previously been reported. The differential diagnosis includes a healing bone infarction or fracture, meningioma, hemangioma, and fibrous dysplasia. Diagnosis prior to surgery is difficult.

Adult↗
PubMed1992

[A ruptured aneurysm at the peripheral collateral circulation of the anterior choroidal artery in a patient with moyamoya disease: a case report].

This 42-year-old man experienced a sudden onset of occipital headache. Neurological examination revealed a moderately disturbed consciousness and a moderate left hemiparesis. CT scan disclosed a hugh hematoma in the right temporo parietal lobe without intraventricular hemorrhage. A cerebral angiography demonstrated typical findings of moyamoya disease and a small saccular aneurysm at the peripheral portion of the right anterior choroidal artery, which was dilated at the collateral circulation to the parietal lobe. The hematoma was removed at once by a craniotomy. He became alert but mild hemiparesis persisted. MRI disclosed a small signal-void lesion lateral to the trigone of the right lateral ventricle. The angiography repeated three weeks after the removal of the hematoma showed the unchanged size of the aneurysm. Direct surgery for the aneurysm was performed via the right parietal transcortical approach. The aneurysm was reached under the guidance of the intraoperative angiography. Trapping of the parent artery and the excision of the aneurysm were performed. On the basis of the presence of an internal elastic lamina at the neck of the aneurysm, the surgical specimen was histologically verified to be a true aneurysm. Since the collateral circulation was well preserved during surgery, no worsening of the neurological manifestation was observed. In view of the unfavorable prognosis for a moyamoya patient with this type of the aneurysm, which often results in a massive ventricular or intracerebral hemorrhage, surgery directed to the aneurysm itself should be considered.

Adult↗