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Biomedical subjects

S Toya

Publications and source records attributed to S Toya.

At least 73 records · Page 4Linked to original sources
PubMed1993

Propentofylline (HWA285) inhibits the release of dopamine during transient ischemia and modulates its metabolism in rat striatum.

Propentofylline (HWA285) has been reported to protect neuronal cells through the inhibition of glutamate release during transient ischemia. We studied whether HWA285 inhibits dopamine (DA) release, and how HWA285 modulates DA metabolism in the rat model. HWA285 was perfused through a microdialysis probe placed in the rat striatum during 20 min transient ischemia. In rats perfused by HWA285, ischemic DA release was significantly inhibited, and DA metabolism showed better recovery in contrast with unperfused rats.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1993

Immunohistochemical analysis of 61 pituitary adenomas with a monoclonal antibody to the neuron-specific beta-tubulin isotype.

Pituitary adenomas surgically resected from 61 consecutive patients and 9 normal pituitary glands were studied by immunohistochemistry to determine the localization of the class III beta-tubulin isotype(neuron-specific) which is recognized by the monoclonal antibody TUJ1. In normal pituitary glands only a few cells were weakly immunopositive for TUJ1, whereas, in 43(73%) of 61 adenomas, more than 5% of tumor cells were immunopositive. The result may indicate that this neuron-specific beta-tubulin isotype may be either expressed de novo or enhanced under the transformation of pituitary acinar cells to tumors.

Adenoma↗
PubMed1993

In vivo effect of visible light on feline cortical microcirculation.

The present study was designed to test the hypothesis that prolonged illumination of the cerebral cortex, for instance during neurosurgical interventions, may affect the pial microcirculation. Experiments were performed with the closed window technique in cats. The cortical surface below the window was exposed to visible, cold light of 61,000 lumens/m2 (lux) over a period of 1 to 5 hours. Pial arterioles reacted with a slight initial dilatation to 106.8 +/- 2.6% of their resting diameter after switching to the high intensity light. Measurements of the cortical surface temperature showed an average temperature increase of 1.5 +/- 0.34 degrees C within the first 10 minutes of illumination. For assessment of pial vascular function, the responses to topical application of acetylcholine (ACh) were tested before and during the illumination period. The effect of sustained illumination on the cortical microcirculation consisted of abolition of the endothelium dependent relaxation due to ACh, and of intravascular thrombus formation, the latter, however, only in the presence of topically applied ACh. The suspected mechanism responsible for these functional alterations is light-induced generation of free oxygen radicals which are known to inactivate or destroy the endothelium-derived relaxing factor (EDRF). Further studies are recommended to elucidate the practical and clinical relevance of these findings to neurosurgical procedures.

Acetylcholine↗
PubMed1993

Prolactin presents in all pituitary tumors of acromegalic patients.

Twenty-two consecutive cases of adenoma in acromegalic patients were studied immunohistochemically. All the tumors contained prolactin (PRL)-reactive cells (3% to 53% of the total number of tumor cells) as well as growth hormone (GH)-reactive cells (4% to 74% of the total number of tumor cells). All acromegalic cases studied were thus plurihormonal adenomas containing GH and PRL; no pure GH cell adenoma was present. Twenty cases were further examined at the ultrastructural level in conjunction with postembedding double-labeling immunoelectron microscopy; 15 of these cases were diagnosed as mixed GH cell-PRL cell adenomas. The previously diagnosed pure GH cell adenomas possibly may have contained PRL cells and thus should be considered as mixed GH cell-PRL cell adenomas. Mammosomatotroph adenomas were rare in this series. Double-labeling immunoelectron microscopy, using protein A gold particles of two different sizes, greatly facilitated the distinction among GH, PRL, and mammosomatotroph cells.

Acromegaly↗
PubMed1993

Serious adverse effects induced by simultaneous administration of two nonsteroidal anti-inflammatory drugs.

We have described the case of a 58-year-old woman in whom acute hemolytic anemia, renal failure, and granulocytopenia developed after intake of mefenamic acid and diclofenac. Results of direct and indirect Coombs' tests were negative, but the lymphocyte transformation test was positive for these two nonsteroidal antiinflammatory drugs (NSAIDs). We suggest that the immune complex mechanism could have induced these adverse reactions. Although these drugs are very popular, simultaneous administration should be avoided because serious adverse effects can potentially occur.

Acute Kidney Injury↗
PubMed1993

Epidermoid cysts of the callosal region--three case reports.

Three patients with rare epidermoid cyst in the callosal region are described, two adjacent and one in the corpus callosum. Computed tomography revealed atypical features, i.e. a large, well-defined high-density mass unenhanced postcontrast and a well-defined hypodense mass with marginal calcification in one case each. Such a diffuse high-density mass may be caused by hemorrhage, highly concentrated protein or calcification of keratinized debris within the cyst. Marginal calcification may occur for unknown reasons. The cysts were subtotally removed.

Adult↗
PubMed1993

[Transcranial magnetic stimulation of the facial nerve--identification of the actual excitation site in the cat].

The site where transcranial magnetic stimulation excites the facial nerve was studied in 6 cats. Transcranial magnetic stimulation of the facial nerve was recorded from the left mentalis muscle. A figure-of-eight shaped magnetic coil was used, and coil induction direction had more influence on the facial nerve evoked compound muscle action potentials (CMAPs) than the coil position. No change could be detected in the CMAPs before and after craniotomy, after cerebellar lobectomy and after exposure of the facial nerve in the facial canal. The facial nerve was stimulated electrically at the porus, meatal portion, geniculum and horizontal portion. The latencies of the CMAPs for each portion were measured and compared with the magnetic response, which was coincidental with that of the meatal portion. The facial nerve was then transected distally from the porus, and CMAPs following magnetic stimulation were recorded at each step. The CMAPs disappeared when the nerve was transected at the fundus. The results of both approaches in this study led to the conclusion that transcranial magnetic stimulation excites the facial nerve at the meatal portion.

Action Potentials↗
PubMed1992

Glycopeptide of P0 protein inhibits homophilic cell adhesion. Competition assay with transformants and peptides.

Expression of major myelin glycoprotein P0 by P0 cDNA transfection into C6 glioma cells promoted homophilic cell adhesion of the cells. After the dissociated cells were incubated for various times, the number of particles at each time point was measured. The total number of particles decreased to 24% in 60 min for transformant (C6P0) cells, in contrast to only 68% for control (C6P0') cells. To confirm the homophilic mechanism of adhesion, mixed-cell aggregation experiments were performed. Among the four synthetic peptides corresponding to a part of the P0 sequence used, only peptide 3 (residues 90-96), which contained a carbohydrate attaching site, caused considerable inhibition of cell aggregation (approximately 50%). In addition, the glycopeptide (residues 91-95) obtained from bovine P0 markedly inhibited cell aggregation (by approximately 85%).

Amino Acid Sequence↗
PubMed1992

Reversibility of energy metabolism and intracellular pH after cerebral ischaemia evaluated by 31P-MRS.

We have previously developed a reproducible model of transient forebrain ischaemia in rats by bilateral carotid artery occlusion combined with temporary increase of ICP. With this model, reversibility of the energy metabolism and intracellular pH (pHi) was investigated by 31P-MRS during 120 min of recirculation in three groups of, respectively, 30, 60, and 120 min of ischaemia. With the induction of ischaemia, ATP and phosphocreatine (PCr) disappeared, and measurement of pHi showed severe acidosis in all rats. In the 30 min ischaemia group, both energy metabolism and pHi recovered almost completely. In the 60 min ischaemia group, ATP recovered to 74% of control values, but pHi showed full recovery. In the 120 min ischaemia group, ATP recovered to about 50% of control values, and recovery of pHi was variable. Showing logarithmical changes during recirculation in ATP and PCr, the rate of metabolic recovery was fast during 60 min of recirculation, but it decreased and reached plateau thereafter in all groups. Recovery of pHi was affected by ATP levels, and was precipitously accelerated as ATP levels exceeded 50% of pre-ischaemic values. These results suggest that prolongation of the duration of ischaemia limits the restoration of the energy state, and the quality of pHi recovery after cerebral ischaemia is affected by the degree of ATP recovery during 60 min of recirculation.

Adenosine Triphosphate↗
PubMed1992

Usefulness of hemilaminectomy for microsurgical management of intraspinal lesions.

Hemilaminectomy is a limited, unilateral approach to the spinal cord that provides excellent exposure of the dorsolateral and ventral portions of the spinal canal. This approach is most suitable for microsurgical management of the majority of extramedullary tumors. Contrary to conventional laminectomy, the posterior supporting structures of the spine are completely preserved on the contralateral side with this access route. The procedure has been applied in 3 patients who harbored a cervical neurilemmoma, a cervical lipoma, and a thoracic neurilemmoma, respectively. Optimal exposure of the lesion was achieved in each case, and each patient's symptoms improved or completely resolved postoperatively. There were no surgical complications. It is concluded that hemilaminectomy combined with microsurgical techniques should be given priority over standard laminectomy in the surgical management of extramedullary lesions arising in the spinal canal.

Female↗
PubMed1992

Primary non-AIDS related brain lymphoma. Patterns of failure following radiotherapy.

Thirteen patients with primary brain lymphoma (PBL) were treated with radiotherapy. Three patients also had ocular involvement with retinal masses at initial presentation. All but one patient received conventional whole brain irradiation and, in addition, spinal irradiation, intrathecal methotrexate or orbital irradiation were given in two, two and four patients respectively. The radiation doses for involved sites ranged from 40 to 65 Gy, and for prophylactic sites from 30 to 50 Gy. After radiotherapy, all patients had complete regression of the tumor on computed tomography. Nine patients relapsed, 5 of them with brain recurrence. Two patients had ocular recurrence exclusively as their first relapse. The remaining two relapsing patients had bone lesions. One patient died intercurrently. As a result, only three patients are alive and free of disease after 16 to 36 months and all three received some adjuvant treatment in addition to whole brain irradiation.

Adult↗
PubMed1992

Pitfalls in the double labelling immunoelectron microscopy using one face of the grid.

We compared two procedures in the double labelling immunoelectron microscopic method of hormone-storing cells: one-faced and two-faced procedures. With the two-faced procedure we got convincing results consistent with morphological finding, while we often got false results with the one-faced procedure. By the misleading one-faced procedure, the cell storing any one hormone will be misinterpreted as a multihormone storing cell. Therefore, it is concluded that the two-faced method is safer for the double labelling immunoelectron microscopic study.

Amylases↗
PubMed1992

[A case of Turner's syndrome associated with moyamoya disease].

A case of Turner's syndrome associated with Moyamoya disease in a 10-year-old female is presented. This patient had experienced two periods of syncope and transient right hemiparesis in 2 years. She was short in stature. She had cubitus vargus and mental retardation. The serum LH and FSH values were high. By chromosomal examination Turner's syndrome (karyotype: 45, X/46, X, i(Xq)) was diagnosed. An MRI (SE 2000/20) revealed abnormal vessels on the basal ganglia. Cerebral angiography showed occlusion of bilateral internal carotid arteries at the distal portion, bilateral posterior cerebral arteries at the proximal portion. Basal moyamoya well developed. EDAS (encephalo-duro-arterio-synangiosis) was performed bilaterally. We consider that this may be the first case report of Turner's syndrome associated with Moyamoya disease, and that there may be no relationship between Turner's syndrome and Moyamoya disease in this case.

Cerebral Angiography↗
PubMed1992

[Natural history for residual intracranial AVM: compared with that for conservatively treated AVM].

It is generally accepted that the most suitable treatment of AVM is surgical removal which does not cause neurological deficits. But in some cases, it is impossible to treat surgically because of size or location, so the patient is unfortunately discharged with some part of the nidus remaining. In this paper, we report the natural history of residual AVMs in which part of the nidus remained after initial therapy, and try to ascertain whether therapeutic reduction of the nidus is more effective in preventing intracranial hemorrhage than conservative treatment. Of 362 cases, residual AVMs were found in 35 cases, and were followed up for 9.2 years on average. Eighty cases treated with only conservative therapy were also followed up for 10.9 years on average. The annual risk of intracranial hemorrhage for residual AVMs was 2.9% and that for conservatively treated AVMs was 3.0%, not a significant difference. There was no difference between the two groups in mortality or ADL. We conclude that therapeutic reduction of the nidus was not effective in preventing intracranial hemorrhage.

Adolescent↗
PubMed1992

[Traumatic intracranial aneurysms after removal of tuberculum sellae meningioma: case report].

Two cases of traumatic aneurysms (TA) of the internal carotid artery (IC) due to removal of tuberculum sellae meningioma (TSM) are presented, and ideal treatment of those aneurysms is discussed. The tumor, compressing the IC laterally, was removed out without arterial injury in case 1. Though the patient's postoperative course was uneventful, frontal and intraventricular hemorrhage developed 2 months after the operation, and an IC dorsal aneurysm was detected. Preoperative angiograms showed no aneurysm, so it was considered to be a traumatic aneurysm due to the surgical procedure. The aneurysm was clipped at once, but postoperative angiograms showed recurrence of the aneurysm. IC balloon occlusion was carried out as the Matas test was negative. In case 2, a small tear in the IC was inadvertently made during recurrent TSM removal, which was wrapped with muscle using fibrin glue. 2 weeks after the operation, frontal hemorrhage developed. Angiograms revealed a small aneurysm of the IC, which was considered to be a traumatic aneurysm. IC balloon occlusion was performed as the Matas test was negative. These 2 patients have had no episodes of rerupture after the IC balloon occlusion. Tumors and main arteries are frequently adhesive, so arteries are easily injured during removal of meningiomas. Muscle wrapping was not enough to prevent TA formation. Neck clipping was not appropriate for treatment of TA, but IC balloon occlusion was an effective and excellent therapy for TA of IC.

Adult↗