Biomedical subjects

Y Yonemasu

Publications and source records attributed to Y Yonemasu.

At least 37 records · Page 2Linked to original sources

PubMed1996

Dural invasion and proliferative potential of pituitary adenomas.

The relationship between invasiveness and proliferative potential was studied in 31 cases of pituitary adenomas. The invasiveness was determined by histological examination of sellar floor dura resected during transsphenoidal surgery. The proliferative potential of adenoma specimens was examined immunohistochemically using monoclonal antibody (MIB-1). There were 11 adenomas with histologically verified dural invasion out of 31 cases. These adenomas had a higher MIB-1- positive ratio than adenomas without dural invasion (p < 0.05). Pituitary adenomas with a high proliferative potential tend to be invasive.

Adenoma↗

PubMed1996

Intraoperative electrocorticography in children with medically intractable epilepsy.

Intraoperative electrocorticography (ECoG) was performed to localize epileptic foci in 20 children undergoing temporal and extratemporal surgery for intractable epilepsy under modified neuroleptanalgesia. Nitrous oxide gas was discontinued at least 15 minutes before and during preresection ECoG recording, which lasted for 30 minutes. Seventeen patients showed epileptiform discharges on preresection ECoG. Hyperventilation loading, monitored by electroencephalography or ECoG in all patients, induced enhanced or induced epileptiform activities in 17 patients and provoked electroencephalographic seizures in 10 patients. All foci in non-eloquent areas were resected. Fifteen patients have been seizure-free with reduced medication, and two patients have achieved worthwhile improvement. Habitual seizures have remained in three patients. Two of these patients had foci in eloquent areas which could not be resected. Intraoperative ECoG can improve the outcome of surgery for intractable epilepsy by localizing epileptic foci for resection.

Adolescent↗

PubMed1996

[A case of Jefferson fracture treated with the Sof'wire cable system method of fixation].

Jefferson fracture is a very rare disease which occurs in only 2-13% of all cervical spinal fracture cases and in only 1.3% of total spinal fracture cases. A combination of an atlas-axis fracture occurs relatively frequently and with a higher incidence of neurological morbidity than isolated fractures. However, a Jefferson fracture, which is an isolated C-1 fracture, occurs very rarely. A 58-year-old woman was involved in a traffic accident and admitted to our hospital. She had a large scalp laceration in the parietal region and complained of nuchal pain. Neurological examination revealed nothing abnormal. A cervical x-p (lateral view) revealed no abnormal findings, but an open-mouth view revealed an 8 mm displacement (in total) in the lateral mass of the atlas. A cervical CT revealed a Jefferson fracture. Crutchfield traction was performed for 9 days followed by external immobilization with a halo-vest to allow the patient to be ambulatory quickly. A posterior occipitocervical fusion was performed with an iliac bone autograft using the Sof'wire Cable system for late cervical stability and reducing the period of rigid external immobilization. The postoperative state was uneventful. The halo-vest was removed 10 weeks after surgery. An x-p obtained 3 months postoperatively showed good stability of the cervical spine. The Sof'wire Cable system proved to be very useful.

Accidents, Traffic↗

PubMed1996

[Familial multiple cavernous angioma in the brain and spinal cord].

We reported two patients from the same family underwent operation for neurological symptoms due to vascular lesions that were proved on pathological examination to be cavernous angiomas. Case 1, a 64-year-old woman was admitted to our hospital because of paraparesis. MRI revealed a mass lesion with high signal intensity in T1 and T2 weighted images at T3-4 level. Complete excision was carried out and diagnosis of cavernous angioma was made. Three years later, she experienced a mild headache and dizziness. CT scan demonstrated a subcortical hematoma in the right frontal lobe. Postoperative pathological diagnosis was cavernous angioma. Case 2, a 65-year-old woman (younger sister of case 1) was operated for the tumor of spinal cord, and diagnosed as a cavernous angioma. Two years later, she developed diplopia and ataxic gait. MRI showed multiple cavernous angioma in the brain including pons. Pontine lesion which was responsible for this episode was removed, and diagnosis was a cavernous angioma histopathologically.

Aged↗

PubMed1995

Zonisamide: electrophysiological and metabolic changes in kainic acid-induced limbic seizures in rats.

We studied the pharmacological mechanism of zonisamide (ZNS) using an electrophysiological and autoradiographical method in a limbic seizure model in rats. Limbic seizure status epilepticus was induced by a unilateral microinjection of kainic acid (KA) into the amygdala. Initially, observed seizures were limited to the side of the injected amygdala and then propagated to bilateral sensorimotor cortex. Eighty minutes after injection, secondarily generalized seizure status epilepticus was induced, with each seizure lasting approximately 30 s and recurring every 5 min. ZNS 100 mg/kg was administered intravenously (i.v.) during the generalized seizure. Forty minutes after ZNS administration, epileptic activity was observed only at the KA-injected amygdalar site and spikes were not observed in the bilateral sensorimotor cortex. We studied local cerebral glucose utilization (LCGU) after ZNS or saline administration using an autoradiographical method in the same limbic seizure preparation. In the ZNS group, LCGU decreased in the ipsilateral sensorimotor cortex and hippocampus, whereas in the controls LCGU increased in these structures. On the other hand, ZNS did not suppress the epileptic activity of the primary focus and no decrease in LCGU was observed in the KA-injected amygdala. ZNS inhibited seizure propagation from the epileptogenic focus but did not suppress the epileptic activity of the focus. Our results suggest that ZNS is effective for the treatment of secondarily generalized seizure.

Animals↗

PubMed1995

Cavernous sinus invasion by pituitary adenomas--relationship between magnetic resonance imaging findings and histologically verified dural invasion.

The relationship between magnetic resonance (MR) imaging findings and histologically verified invasion of the cavernous sinus by tumor cells was studied in 26 patients treated surgically for pituitary adenoma. Dural invasion of the sellar floor by tumor cells was found in 10 cases (38%). All patients were classified according to MR imaging findings into three types. Type I showed a gadolinium-enhanced stripe medial to the carotid artery (5 patients), none of which showed dural invasion. Type II showed no enhanced stripe (17 patients), six of which showed dural invasion. Within this type, tumor size and dural invasion showed no correlation. Type III showed displacement or encasement of the carotid artery by the tumor with or without extracranial extension (4 patients), all of which showed massive infiltration of the tumor cells into the dura mater. This study shows that preoperative MR imaging can provide information for assessment of invasion into the cavernous sinus in patients with pituitary adenoma.

Adenoma↗

PubMed1995

[De novo aneurysm associated with a persistent primitive trigeminal artery: case report].

This paper presents a case of a de novo unruptured anterior communicating aneurysm associated with a persistent primitive trigeminal artery. The patient was a 65-year-old female with tinitis, for whom computed tomography with contrast medium indicated right dural enhancement. Dural arteriovernous malformation was suspected and angiography was thus conducted. A right persistent primitive trigeminal artery was demonstrated but no aneurysm could be found. Six years later, magnetic resonance angiography indicated an aneurysm on the anterior communicating artery. It was subsequently removed by surgery. A persistent primitive artery is frequently found to accompany aneurysm but de novo aneurysm associated with such an artery does not appear in the literature to date. The authors emphasize the importance of follow-up angiography in cases of persistent primitive artery not accompanied by an aneurysm.

Aged↗

PubMed1995

[Posttraumatic pseudoaneurysm of the middle meningeal artery: a case report].

An epidural hematoma associated with posttraumatic pseudoaneurysm of the middle meningeal artery is a very rare clinical entity. Only 31 such cases have been reported in the literature. A 54-year-old man was admitted with lethargy and right hemiparesis. A skull X-ray film revealed a linear fracture in the left parietal and temporal bone, extending to the base of the skull. A brain CT scan disclosed an acute epidural hematoma over the left cerebral hemisphere, contusional hematoma in the right frontal lobe and thalamus, and subarachnoid hemorrhage in the left Sylvian fissure. During an emergency craniotomy a large epidural hematoma was evacuated and external decompression was performed. Angiography, which was performed about one month after the head injury, revealed an aneurysm of the middle meningeal artery. The aneurysm was removed to avoid delayed rupture at the time of cranioplasty. Histological diagnosis was pseudoaneurysm. We discussed the pathogenesis of a pseudoaneurysm of the meningeal artery and the necessity to pay attention to the presence of a pseudoaneurysm when an active bleeding point is not observed during surgery of the epidural hematoma.

Aneurysm, False↗

PubMed1995

[Jacksonian seizure model induced by a kainic acid microinjection into unilateral sensori-motor cortex].

Kainic acid microinjection into unilateral sensori-motor cortex induced focal seizure status and secondarily generalized seizure status for about 4 hours. After these seizure status, focal myoclonic jerkings were induced for about 2 days. EEG demonstrated generalized synchronous periodic spikes with these myoclonic jerkings. This phenomenon was very similar to those symptoms of epilepsia partialis continua in man. During focal seizure status, autoradiographic study with 14C-deoxyglucose demonstrated increased local cerebral glucose utilizations in the injected site of the sensori-motor cortex, ipsilateral caudate nucleus, globus pallidus, substantia nigra and thalamic nuclei. The result suggested that subcortical pathways played an important roles in the seizure propagation from the cortical epileptogenic focus.

Animals↗

PubMed1994

Accumulation of exogenous 45Ca after middle cerebral artery occlusion in rats.

The distribution of exogenous 45Ca in the focal ischemia rat model (middle cerebral artery occlusion) was studied using 45Ca autoradiography. High 45Ca accumulations were observed in the frontal cortex and caudate-putamen corresponding with morphological damage shown by HE staining. Regional 45Ca concentrations were calculated from the optical density on the 45Ca autoradiograms. Rapid uptake of 45Ca in the ischemic brain occurred during the first 5 hours, and continued more slowly between 5 and 24 hours after ischemia. The area of 45Ca accumulation was also expanded between 5 and 24 hours. An area of low 45Ca concentration around the area of high accumulation developed 5 hours after ischemia, which presumably accumulated 45Ca between 5 and 24 hours after ischemia. The lower concentration of 45Ca in the periphery of ischemia may result from: 1) a decrease in the total amount of calcium due to narrowing of extracellular space accompanied by cytotoxic edema, and 2) delayed accumulation of exogenous 45Ca due to reduced clearance of extracellular fluid.

Animals↗

PubMed1994

[Basic and clinical approaches for surgical treatment of intractable epilepsies].

Recent reports demonstrated that patients with medically intractable epilepsy were benefited with surgical treatments. Even in pediatric patients, early surgery is effective not only in seizure control but also in verbal, intelligent and social outcomes. In the present study, basic and clinical approaches in the treatment of intractable epilepsies were studied. In chronic cat model of intractable temporal lobe epilepsy induced by a microinjection of kainic acid, temporal cortical excision with amygdala focus resection or focus and hippocampal resections were examined by means of microsurgical technics. The cats with amygdala focus resection demonstrated spontaneous hippocampal seizures while cats with focus and hippocampal resection did not show seizures in the long time course after the surgery. In a cat model of cortical focal seizures, multiple subpial transection(MST) was examined. The cortical seizures, induced by a microinjection of kainic acid into unilateral sensori-motor cortex, were suppressed immediately after the MST. Postoperative course was uneventful and seizure was not recurred. However, pathological study demonstrated subpial scar formation at the site of MST in the sensori-motor cortex. In 38 patients with medically intractable epilepsies, surgical treatments were performed in the Department of Neurosurgery. Asahikawa Medical College. The site of the epileptogenic lesion was studied with Video-EEG longterm monitorings, Neuro-imagings with CT, MRI, interictal SPECT and/or ictal SPECT. At the surgery, intraoperative electrocorticograms(ECoGs) were monitored under light neuroleptanalgesia in order to localize epileptic focus. Seizure free rate with or without postoperative medication was 72%. Remarkable improvement was observed in 7 patients (18%), but, 4 patients (10%) did not show any improvement.

Adolescent↗

PubMed1994

[Electrophysiological and behavioral features of septal seizures in cats--experimental sham-rage seizures induced by injection of kainic acid].

The septal nucleus has close connections with the hippocampus and amygdala and is known to be involved in emotional behavior. We analyzed the electrophysiological and behavioral features of seizures induced by an injection of kainic acid into the lateral septal nucleus of the cat. Stereotactic surgery was performed to implant a cannula into the lateral septal nucleus to make the injection, and deep electrodes were implanted into the hippocampus and amygdala bilaterally. Seven days post operatively kainic acid, 0.5 microgram/0.5 microliter, was injected via the cannula, and three to five minutes later the cats began to exhibit head turning to the contralateral side. The seizures subsequently progressed limbic seizure status. The electroencephalogram revealed that the spike discharges started in the lateral septal nucleus, extended to the ipsilateral hippocampus and amygdala, then propagated to the contralateral side. Spontaneous sham-rage seizures occurred more than seven days after the injection. These seizure were characterized by sudden onset of aggressive and violent behavior which included hissing, biting and scratching. The electroencephalogram showed synchronization of rhythmic spikes in the ipsilateral septal nucleus, hippocampus and amygdala during such seizures. Further study of this model is important not only to understand the relationship between the septal nucleus and the hippocampus and amygdala but to understand the mechanism of sham-rage seizures. In addition, this model may be useful in understanding the emotional features of intractable complex partial seizures in man.

Animals↗

PubMed1994

[Clinicopathological features of dysembryoplastic neuroepithelial tumor (DNT): four cases report].

We reported four cases of dysembryoplastic neuroepithelial tumor (DNT) with intractable complex partial seizures, and analyzed their clinical and pathological features. The age of patients ranged from four to nineteen years old. Three were boys and one was a girl. The age of seizure onset ranged from eight months to five years. They did not have any neurological deficits. In all cases, CT scan revealed a low density mass in the temporal lobe. Two cases demonstrated calcifications, and another two cysts. The mass demonstrated low signal intensity in T-1 weighted MR images with mild contrast enhancement by Gd-DTPA. Long-term video-EEG monitoring revealed the epileptogenic focus in the temporal lobe on the side of the mass lesion. Anterior temporal lobectomy with total removal of the tumor was carried out in all cases. Hippocampectomy was performed in three cases in which intraoperative electrocorticogram demonstrated spike discharges in the hippocampus. In the surgical specimens, the tumor consisted of increased astrocytes, oligodendrocytes, and some neurons. A cortical nodule appeared in one case, and cortical dysplasia appeared in two cases. It was difficult to distinguish the tumor of case 3 from ganglioglioma because of mild neuronal atypia. The tumor of case 4 demonstrated increased capillary vessels and was also difficult to differentiate from vascular anomalies. The pathological diagnosis of DNT was still difficult. Consequently, we speculated that DNT included some transitional types between congenital anomalies and ganglioglioma.

Adolescent↗

PubMed1994

[Ossified epidural hematomas: report of two cases].

Two cases of ossified epidural hematomas were reported. Patients were nine and twelve year-old boys. Initially they were both followed up conservatively after injuries. Subsequently they were found on CT scan to have calcifications in the capsules of epidural hematomas which were found four months after injury in one case and twelve days after injury in the other. Both underwent craniotomy and histological ossification was found in the capsules of the hematomas. Epidural hematomas in children are known to ossify, and this condition may prevent natural absorption of epidural hematomas. Therefore, careful follow up of hematomas seems to be mandatory on conservative therapy of epidural hematomas in children.

Child↗

PubMed1993

The effects of HA1077, a novel protein kinase inhibitor, on reductions of cerebral blood flow and glucose metabolism following acute and/or chronic bilateral carotid artery ligation in Wistar rats.

The effects of HA1077, a novel protein kinase inhibitor on local cerebral blood flow (LCBF) 2.5 h (acute) after permanent bilateral carotid artery ligation (BCAL) and on LCBF and local cerebral glucose utilisation (LCGU) one week (chronic) after BCAL were studied in conscious Wistar rats. Use was made of quantitative autoradiographic 14C-iodoantipyrine and the 14C-2-deoxyglucose techniques and 24 anatomically discrete regions of the brain. HA1077 (1 or 3 mg/kg) or saline was infused i.v. over a 30 min period. HA1077 significantly increased LCBF after acute BCAL in one of the 23 decreased regions in rats given 1 mg/kg, and in 14 of 23 decreased regions in rats given 3 mg/kg, compared to findings in the saline-treated group. Significant increases in LCBF and LCGU after chronic BCAL were noted in seven of the 13 decreased regions and in four of the 11 decreased regions in rats given 3 mg/kg, as compared to observations in the corresponding saline-treated group, respectively. The LCBF and LCGU reductions in forebrain regions with global ischaemia after acute and/or chronic BCAL were overcome by HA1077. These results suggest that HA1077 may be considered for treatment of subjects with acute and chronic cerebral ischaemia, with impairment in cerebral circulation and/or glucose metabolism.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗

PubMed1993

Local cerebral glucose utilisation following acute and chronic bilateral carotid artery ligation in Wistar rats: relation to changes in local cerebral blood flow.

The effects on local cerebral blood flow (LCBF) and glucose utilisation (LCGU) of permanent, bilateral carotid artery ligation (BCAL) were studied in conscious Wistar rats. LCBF and LCGU were measured using quantitative autoradiographic 14C-iodoantipyrine and the 14C-2-deoxyglucose (14C-DG) techniques in 24 anatomically discrete regions of the brain. LCBF in the cerebral hemispheres 2.5 h (acute) after BCAL significantly decreased to 25-87% of the sham control, with the exception of the mammillary body. After acute BCAL, there was a heterogeneous accumulation of 14C-DG in the caudate nucleus and cerebral cortices. Only in the lateral geniculate body did LCGU significantly decrease after BCAL. One week (chronic) later, LCBF was significantly decreased in 15 (containing the caudate nucleus and all the cerebral cortices) of 24 structures. LCGU in ten (containing the caudate nucleus and all the cerebral cortices) of 24 structures after chronic BCAL significantly decreased to 66-77% of the sham control, except for regions with neuronal damage in which there was a heterogeneous uptake of 14C-DG. The ratio of LCBF/LCGU in chronic BCAL was unchanged in comparison with values in the corresponding sham-operated group. This model of acute and chronic cerebral ischaemia, with impairment in cerebral circulation and/or glucose metabolism, is expected to become a pertinent tool for the neurophysiologist.

Animals↗

PubMed1993

Delivery of a novel nitrosourea, MCNU, to the brain tissue in glioma-bearing rats. Intracarotid versus intravenous infusion.

We observed the tissue delivery of a novel water-soluble nitrosourea, 1-(2-chloroethyl)-3-(methyl-alpha-D-glucopyranos-6-yl)-1-nitros our ea (MCNU) in rats bearing experimental brain tumors by conducting autoradiography on all. Prior to this study, the development of a streaming phenomenon was ascertained (and thus finding the optimum velocity for intra-arterial infusion) by 14C-iodoantipyrine (IAP) autoradiography. Furthermore, a single pass extraction value of MCNU was measured. At an arterial infusion rate of 0.2 ml/min., the streaming phenomenon was recognized but the tracer was fairly evenly distributed at a rate of 1.0 ml/min. On the other hand, the single pass extraction value for MCNU was 0.18 +/- 0.036 (mean +/- S.D., n = 3, under pentobarbital anesthesia). It was suggested that MCNU is very unlikely to be transported into the normal rat brain. We conducted 14C-MCNU autoradiography to observe tissue distribution of MCNU following its intra-arterial and intravenous infusions in a brain tumor model using rats. The normal side (the side where no infusions were given) and the cerebral cortex at the side affected by the tumor (the side where the infusion was given) showed hardly any uptake of 14C-MCNU in both the intra-arterial and intravenous infusion groups. The tumorous section was divided into the periphery and the center to measure tissue concentration of the tracer in each section. Compared against the cortical section, the periphery and the center showed significant increases in the concentration (approximately 11 to 15 times and 3 to 7 times, respectively, the figure for the cortical region) for both the intra-arterial and intravenous groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1993

Sequential change of capillary permeability in the rat brain after surgical removal of an experimental brain tumor.

Experimental brain tumors were excised from rats for sequential observation of changes in local capillary permeability during the postsurgical period. Experimental brain tumor-bearing rats were prepared by stereotaxic transplantation of cultured tumor cells and the resultant tumor was delineated by administration of a dye. Following excision of the stained tumor by craniotomy, sequential changes in local capillary permeability were quantitatively followed-up by autoradiography, using 14C-amino-isobutyric acid as a tracer. Capillary permeability was enhanced following surgery, reaching a maximum both in the extent and degree on the third day. After undergoing a gradual reduction, it showed a marked increase for the second time in a very small area on the 10th postoperative day. A recurrence of the tumor was responsible for this late but marked increase. For a control group, the caudate nucleus was excised from normal rats, followed by observation of the sequential changes in the local capillary permeability. Due to surgical procedure, capillary permeability reached a maximum both in the extent and degree on the 5th postoperative day (slightly later than in the tumor group). This change in capillary permeability was less pronounced than in the tumor group. The difference in the conditions of surgery--tumor excision and partial excision of a normal brain tissue--appeared to explain this difference. The results of this study indicated that it is more desirable to give water-soluble antineoplastic agents early during the postoperative period for chemotherapy of a malignant brain tumor after surgery.

Animals↗