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Biomedical subjects

T Morimoto

Publications and source records attributed to T Morimoto.

At least 469 records · Page 26Linked to original sources
PubMed1992

Three types of hyperthermic seizures in rats.

Three types of rat hyperthermic seizures were observed. The first comprised generalized clonic convulsions preceded by intermittent myoclonus. Ictal EEG showed diffuse intermittent spikes and sequential rapid spike-wave bursts (type 1 seizures). In the other types of seizures, the paroxysmal discharges originated in the occipital region without (type 2a seizures) or with (type 2b seizures) secondary generalization. Type 2a seizures involved no convulsive movement whereas type 2b seizures involved clonic convulsions. The threshold temperatures for type 1, 2a and 2b seizures were 44.1 +/- 0.60, 40.9 +/- 1.47 and 42.1 +/- 0.75 degrees C, respectively. Of these seizures, the type 2 seizures (2a and 2b) did not severely affect the general condition of rats and thus may be an appropriate model for the investigation of febrile seizures.

Animals↗
PubMed1992

Extent of ischaemia caused by hepatic vascular exclusion as evaluated in a canine model.

1. The difference in the extent of liver ischaemia between a hepatic vascular exclusion model and an inflow occlusion model were investigated by determining Indocyanine Green retention and hepatic mitochondrial redox state during 2 h of ischaemia in 10 mongrel dogs. The splanchnic venous bed and/or the infra-hepatic inferior vena cava were decompressed by pump-driven veno-venous bypass. 2. The Indocyanine Green retention test revealed that there was no hepatic blood flow in the hepatic vascular exclusion model during ischaemia (96.8 +/- 0.73% retention of the dye after 20 min), whereas hepatic blood perfusion was still present significantly in the inflow occlusion model (78.1 +/- 1.19% retention of the dye after 20 min) (P less than 0.01). 3. The mitochondrial redox potential of the liver in the dogs with hepatic vascular exclusion decreased immediately after the induction of ischaemia and remained fixed at extremely low levels. By contrast, in the dogs with inflow occlusion the redox potential decreased gradually after induction and was maintained significantly higher than that in dogs with hepatic vascular exclusion during 2 h of ischaemia (P less than 0.01). 4. It is concluded that the extent of liver ischaemia in the hepatic vascular exclusion model with pump-driven shunt is significantly different from that in the inflow occlusion model with shunt.

Animals↗
PubMed1992

Chondrosarcoma of the skull base: report of six cases.

Five patients with chondrosarcoma, grade I or II, and one with mesenchymal chondrosarcoma of the skull base were treated at our clinic between 1967 and 1991. The patients were three men and three women who ranged in age from 21 to 39 years. The presenting symptoms were diplopia, decreased visual acuity, or symptoms of involvement of VIIIth and lower cranial nerves. The duration of the symptoms ranged from 18 months to 14 years. A plain skull x-ray and tomography of the skull, computed tomographic (CT) scans, and magnetic resonance images (MRI) revealed a calcified mass. Angiograms showed an occlusion of the arteries or venous sinuses, or both, in four patients, and a distinct tumor stain in one. The tumors were subtotally removed in all six cases. Two patients received postoperative irradiation for the residual tumor. In one patient, extraocular movement was compromised postoperatively, although in the other five patients there was no aggravation of the neurologic signs. Follow-up CT scans and MRI demonstrated no recurrent tumors nor any enlargement of residual tumors. Based on these findings, we advocate aggressive surgical removal of these tumors, which should be augmented by radiation therapy if the postoperative CT scans or MRI reveal residual tumors.

Journal Article↗
PubMed1992

Mechanism underlying the changes in plasma potassium concentration during infusion of isosmotic nonelectrolyte solution.

Generally, during infusion of an isosmotic nonelectrolyte solution that permeates the cell membrane, plasma K+ concentration ([K+]pl) either does not change or it increases slightly. The mechanism underlying this [K+]pl change has not been clarified. We continuously monitored the [K+]pl and plasma Na+ concentration ([Na+]pl) for 10 min during isosmotic mannitol infusion of 1.6 ml/100 g body weight in rats with intact kidney function (intact mannitol group). In addition, in nephrectomized rats, we compared the [K+]pl change during infusion with isosmotic mannitol (which permeates the cell membrane; mannitol nephrectomized group) with that during infusion with isosmotic sucrose (which does not permeate the cell membrane; sucrose nephrectomized group) to evaluate the effect of cell volume regulation. In the intact mannitol group, [Na+]pl decreased with dilution, and [K+]pl remained relatively constant. In the sucrose nephrectomized group, [K+]pl decreased by the same percentage as [Na+]pl and gradually increased to greater than the control level. In the mannitol nephrectomized group, however, [K+]pl increased immediately after the beginning of the infusion and reached the same level as that in the sucrose nephrectomized group. To confirm that the difference in [K+]pl between the mannitol and sucrose nephrectomized groups was dependent on cell volume regulation, we investigated the changes in mean corpuscular volume of red blood cells, using a Coulter counter. This value remained constant during isosmotic sucrose infusion but increased during isosmotic mannitol infusion, returning to the original volume after the infusion. We kept [HCO3-] and pH constant throughout the experiments.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Analyses of the risk and operative stress for donors in living-related partial liver transplantation.

Operative risk and stress were analyzed in 28 parent-donors whose children received partial liver transplantations at the Second Department of Surgery, Kyoto University Hospital between June 1990 and December 1991. Graft-harvesting operations were classified into three types: left lobectomy (group L, n = 12), left lateral segmentectomy (group S, n = 15), and right lobectomy (n = 1). Since donor safety is a primary concern, great care was taken to minimize potential damage to the remaining lobes of the donor liver as well as the graft liver by avoiding stressful maneuvers such as hepatic vascular clamping during the transection of the hepatic parenchyma. In all cases the arterial ketone body ratio, which reflects the hepatic mitochondrial redox potential, was maintained at over 0.7 throughout the donor operation as well as postoperatively. There was no significant difference in the postoperative RBC, WBC, serum GOT, and total bilirubin between groups L and S, although the abnormalities exhibited by the single right lobectomy case tended to be larger and more prolonged. All cases were within the range acceptable for immediate discharge, and all donors of groups L and S were subsequently discharged within 14 days without any postoperative complications. The single right lobectomy donor was discharged on POD17 because of transient slight icterus, which is the only postoperative complication encountered in this series thus far. The present analyses would indicate that the risk and operative stress to the donor in living-related partial liver transplantation can be minimal when the left lobe or left lateral segment of the liver is used for the graft.

Aspartate Aminotransferases↗
PubMed1992

Elevated mean systemic filling pressure due to intermittent positive-pressure ventilation.

To clarify the effect of intermittent positive-pressure ventilation (IPPV) on systemic circulation, mean systemic filling pressure (Psf) and circulating blood volume were measured together with other hemodynamic parameters of capacitance vessel. Change in circulating blood volume was determined by dilution with 51Cr-labeled erythrocytes. Vascular compliance (Cvas) was measured from the change in Psf caused by a bolus injection of blood. These parameters were measured during both spontaneous respiration and IPPV in male Wistar rats anesthetized with pentobarbital sodium. The shift from spontaneous respiration to IPPV reduced cardiac output (CO) by 20.9%. Psf increased significantly, from 7.1 +/- 1.2 to 8.6 +/- 1.1 mmHg. Central venous pressure (Pcv) also increased significantly. The pressure gradient for venous return decreased by 15.6% (from 6.4 to 5.4 mmHg). The resistance to venous return did not change significantly, but there was a significant increase in total peripheral resistance. Neither Cvas nor circulating blood volume was changed significantly by IPPV. These results indicate that during IPPV the increased Pcv attenuates the pressure gradient for venous return and decreases CO and that the compensatory increase in Psf is caused by a blood shift from unstressed to stressed blood volume.

Animals↗
PubMed1992

Continuous measurement of Na concentration in CSF during gastric water infusion in dehydrated rats.

To assess the differential stimulus to central and intravascular osmoreceptors during recovery from thermal dehydration, we measured Na concentrations in cerebrospinal fluid ([Na]CSF) and plasma ([Na]p) continuously and compared these during simulated drinking by gastric water infusion (INF) in euhydrated and thermally dehydrated rats under anesthesia. Continuous measurement of [Na]CSF was obtained with a double-barreled Na electrode placed in the lateral ventricle. Continuous measurement of [Na]p was obtained from a flow cell Na electrode in an extracorporeal shunt. Measurements were made during 10 min of INF (2.5 ml/100 g body wt) into the stomach and during 20 min of recovery. Changes in [Na]CSF always lagged behind those in [Na]p and were quantitatively smaller after INF. The decrease in [Na]CSF occurred sooner in dehydrated than in euhydrated rats in response to the decrease in [Na]p (P < 0.01). These results suggest that water and/or Na movement between blood and CSF is accelerated during restitution from thermal dehydration, acting to prevent overhydration during the early phase of rehydration.

Animals↗
PubMed1992

Primary adult T-cell lymphoma of the breast.

A case of primary adult T-cell lymphoma (ATL) of the breast is described. A 69-year-old woman presented with a painless, rapidly growing lump in her left breast. Staging procedures demonstrated no sign of generalized disease. Following a Patey's mastectomy, 10 courses of adjuvant chemotherapy (CHOP) were successfully administered. The light microscopic, immunohistochemical and molecular genetic analyses of the surgical specimen revealed a primary ATL. Seropositive mothers who breast-feed their children may facilitate the accumulation of T cells carrying HTLV-I in their breasts and thereby increase their risks of developing breast ATL.

Aged↗
PubMed1992

Dural arteriovenous malformation in the cervical spine presenting with subarachnoid hemorrhage: case report.

Most spinal dural arteriovenous malformations are located in the thoracic and lumbar regions. The symptoms include pain, weakness, sensory disturbances, and sphincter dysfunction, which are usually gradual in onset. They are attributed to venous hypertension with a resultant ischemia of the cord, and hemorrhage from them is rare. The authors report an unusual case of a patient with a dural arteriovenous malformation in the cervical spine who was admitted with a sudden onset of severe headache and dysesthesia due to subarachnoid hemorrhage.

Cerebral Angiography↗
PubMed1992

[Effects of mosapramine (Y-516), a new dopamine D2 antagonist, on reverse tolerance after repeated administration of methamphetamine by means of the ambulation-increasing effect in mice].

Effects of mosapramine (Y-516), a new dopamine D2 antagonist, on reverse tolerance (sensitization) after repeated administration of methamphetamine (MAP; 2 mg/kg, s.c.) were investigated by means of ambulatory activity in mice; and they were compared with those of clocapramine (CCP), bromperidol (BPD) and chlorpromazine (CPZ). Y-516 (0.3, 1, 3 and 10 mg/kg, p.o.), CCP (3, 10 and 30 mg/kg, p.o.), BPD (0.1, 0.3 and 1 mg/kg, p.o.), CPZ (1, 3 and 10 mg/kg, p.o.) or 0.5% methylcellulose (MC; solvent, p.o.) were given to mice 30 min before MAP administration. The ambulatory activity was measured by tilting-type activity changes for 3 hr after MAP. These treatments were repeated 5 times at 3-4 day intervals. Then MAP alone was challenge-administered to all of these mice 3-4 days after the final administration. Marked reverse tolerance was produced after repeated administration of MC plus MAP. On the other hand, the ambulation-increasing effect of MAP was suppressed dose-dependently in groups pretreated with Y-516 or comparison-drugs, although the development of reverse tolerance was not completely inhibited after the repeated administration. In the challenge-administration of MAP, the ambulation-increasing effect was dose-dependently suppressed in the Y-516 group or the comparison-drug plus MAP group as compared with that in the MC plus MAP group.

Animals↗
PubMed1992

Cortical and subcortical cavernous angioma: a comparison of patients with and without hemorrhage as the initial symptom.

Cavernous angioma is a benign vascular hamartoma with an obscure etiology. Clinical, radiological, and histological features of 24 cases of cortical and subcortical cavernous angiomas were analyzed to investigate the etiology. The lesions were classified as hemorrhaging (8 cases) or non-hemorrhaging (16 cases) according to the initial symptom. Age, sex, location, calcification and postcontrast enhancement by computed tomography (CT), tumor staining by angiography, and calcification and hemosiderin by histological examination were analyzed. Multivariate analysis showed that calcification by CT and histological examination correlated with non-hemorrhaging cases. Histological examination showed that calcification occurred inside and outside the blood vessels, within the vessel walls and in the adjacent brain tissue. Hemosiderin was also seen in most cases. These findings suggest that cavernous angiomas without hemorrhage have a poor circulation, resulting in minor recurrent bleeding and thrombosis, as well as calcification.

Adolescent↗
PubMed1992

Immunohistochemical study of a newly defined oncofetal antigen (HGR-Ag) in tumors of the central nervous system.

The oncofetal antigen (HGR-Ag) in brain tumors was newly defined using the monoclonal antibody derived from tissue extracts of an anaplastic astrocytoma. The HGR-Ag was purified through sequential chromatography using diethylaminoethyl-Sephadex A-50 and Con-A Sepharose affinity columns. The latter method indicated that HGR-Ag is not a glycoprotein, and Western blot analysis indicated a molecular weight of 80-90 kd. Purified antigen was used to produce antibody. This new antibody, designated H1H2, was shown to be an immunoglobulin G1 by immunodiffusion assay. Histological/immunohistochemical studies using the H1H2 antibody on paraffin and frozen tissue sections showed HGR-Ag to be intracellular rather than membrane-associated. The immunoreactivity of H1H2 was highest in malignant astrocytomas, glioblastomas, and normal fetal brain tissue. Neurinomas and certain carcinomas of other organs showed lesser, variable reactivity to H1H2. The strength of the antigen-antibody binding was correlated with the degree of malignancy in human gliomas. H1H2 bound to fetal brain tissue and undifferentiated neural tumors, but not to normal adult brain tissue, so HGR-Ag is probably a fetal oncoantigen.

Animals↗
PubMed1992

Anaplastic astrocytoma of an oncocytic type occurring in the cerebellar vermis in Pierre Robin syndrome--case report.

A 44-year-old male with Pierre Robin syndrome and funnel chest was diagnosed with a tumor of the cerebellar vermis and spontaneous pneumothorax. He received tube thoracostomy for pneumothorax and ventriculoperitoneal shunt for hydrocephalus, followed by radiological examination, subtotal removal of the tumor, pneumonorrhaphy, and chemoradiotherapy. Light microscopy of the tumor sample revealed marked pleomorphism of the tumor cells and numerous giant cells, without mitotic figures. Microcystic changes due to vasogenic edema were also evident throughout the tumor. Electron microscopy showed more than 50% of all tumor cells to be oncocytes, with numerous mitochondria in the cytoplasm. The tumor was diagnosed as anaplastic astrocytoma of an oncocytic type.

Adult↗
PubMed1992

Perfusion pressure breakthrough threshold of cerebral autoregulation in the chronically ischemic brain: an experimental study in cats.

A study was designed to investigate hyperperfusion syndrome after the restoration of normal cerebral blood flow in a chronically cerebral ischemic state resulting from high-flow arteriovenous malformations or severe carotid stenosis. A fistula between the left distal common carotid artery and the jugular vein was created and the left vertebral artery was simultaneously occluded in 44 cats to produce a chronic cerebral ischemic state. For control experiments, 10 cats underwent occlusion of the left common carotid and vertebral arteries. Six weeks later, pial arterial behavior, disruption of the blood-brain barrier (BBB), and cerebral histological changes were investigated using three experimental methods. In the first, in which a fistula was occluded under normal conditions, pial arteries contracted to some 80% of the resting state; however, no BBB disruption or histological changes were observed. In the second experiment, in which a 20-minute occlusion of the left middle cerebral artery was performed in the cats with a patent fistula, a 30% to 40% dilated state of the pial arteries continued after recirculation, and BBB disruption-induced cerebral edema and infarction were observed. These findings were more prominent in the cats that underwent occlusion of the fistula. On the other hand, in the control group, the pial arteries returned to resting size within 40 minutes, and no BBB disruption or histological changes were observed. In the third experiment, in which moderate hypertension was induced for 1 hour, the pial arteries dilated much more remarkably; BBB disruption and cerebral edema were revealed to be more extensive in the cases of fistula occlusion than within those with a patent fistula. In the control group, however, the pial arteries contracted 10% during hypertension, while BBB disruption and histological changes were not evident. The results indicate that the perfusion pressure breakthrough threshold in the chronically ischemic brain may not be reduced by the restoration of normal blood flow, but may be decreased by the addition of new ischemic insults or hypertension.

Animals↗