Search PubMed⌕ Search

Biomedical subjects

M Kabuto

Publications and source records attributed to M Kabuto.

At least 109 records · Page 6Linked to original sources
PubMed1990

Blood-brain barrier disruption caused by impairment of cerebral autoregulation during chronic cerebral vasospasm in primates.

Impairment of the cerebral autoregulation and its effects on the development of brain oedema during chronic cerebral vasospasm after subarachnoid haemorrhage (SAH) were studied in primates. The unilateral induction of SAH by clot placement around cerebral arteries produced a moderate degree of vasospasm (more than 40% reduction of vessel caliber on angiogram) seven days after SAH. Abolishment of autoregulation was observed in the territories of the cerebral hemisphere supplied by the vasospastic arteries. It was found that in this region an increase in cerebral perfusion pressure easily produced a marked elevation of the cerebral blood flow over the upper limit of autoregulation threshold resulting in disruption of the blood-brain barrier.

Animals↗
PubMed1990

Phosphorus-31 magnetic resonance spectroscopy of cerebral ischemia in cats.

The energy metabolism of the brain was measured in three types of ischemic models in the cat using phosphorus-31 magnetic resonance spectroscopy. The cerebral ischemia was produced as follows. In Group 1, two balloons were inflated in the left subclavian artery and the brachiocephalic trunk. In Group 2, the left middle cerebral artery was occluded through a transorbital approach. A combination of the two was employed in Group 3. Phosphorus-31 magnetic resonance spectra were obtained serially during 2 hours of ischemia. Immediately after occlusion, peaks of phosphocreatine and adenosine triphosphate decreased, whereas the peak of inorganic phosphate increased and split in two. Intracellular pH determined by chemical shift of the inorganic phosphate peak decreased. These changes were more pronounced in Group 3 when compared with the other groups. Histological study showed no infarction in Group 1 and infarcted areas in Groups 2 and 3. The size of the infarcted area in Group 3 was larger than that in Group 2. These results suggest that the model of middle cerebral artery occlusion potentiated with the occlusion of the brachiocephalic trunk and the left subclavian artery by balloon catheters is a reliable stroke model and that phosphorus-31 magnetic resonance spectroscopy is useful to understand the pathophysiological state of cerebral ischemia in vivo.

Animals↗
PubMed1990

Effect of endothelin on the canine basilar artery.

Endothelin, a recently discovered peptide produced by endothelial cells, has been shown to have potent constrictor effects on major arteries in vitro. This experiment was performed to determine whether endothelin plays a physiological role in cerebral vasospasm after subarachnoid hemorrhage. A cisternal injection of endothelin (10(-8) mol or 10(-9) mol) caused severe vasoconstriction of the canine basilar artery. The degree of vasoconstriction was dose related and long lasting, persisting for more than 24 hours. This constriction was prevented completely by pretreatment with nicardipine (10(-8) mol). Endothelin produced a marked and transient elevation in blood pressure and might play an important role in cerebral vasospasm. Further investigation will be needed to determine the role of endothelin in the pathogenesis of vasospasm.

Animals↗
PubMed1990

Orbital varix with a pearly phlebolith. Case report.

A patient is described with an orbital varix arising from the right superior ophthalmic vein, associated with ophthalmoplegia and severe pain, and without proptosis. The varix was detected using computerized tomography and orbital phlebography, and at surgery was verified as a venous aneurysm. During the operation, a pearly phlebolith was found. Histological examination of the varix revealed multiple ectatic venous channels. The etiology of this unusual clinical manifestation and the treatment of the patient are briefly discussed.

Calculi↗
PubMed1990

[Current status of air pollution in Sao Paulo, Brazil: effects and problems associated with the introduction of ethanol-fueled motor vehicles].

Recently suggestions have been advanced that alternative fuels including ethanol, methanol or methane instead of so called "fossil fuels" may help improve the current conditions of air pollution. According to results of general survey in Sao Paulo, since their introduction in 1978, ethanol-fueled cars have increased their share to almost 50% of all light vehicles in 1983. The current status of air pollution in Sao Paulo metropolitan area (SPMA) is described in relation to the use of such alternative fuel. The average concentrations in air of SO2 and lead have been decreasing drastically during the period of 1982-88, whereas non-methane hydrocarbon, NO2 and O3 levels have been increasing to attain the worst levels in the world as indicated in Fig. 2. The use of ethanol-fuel, which contains less sulphate and lead, is thought to have contributed more or less to the above reductions of SO2 and lead in the air. However, the pollutants that have increased may derive mainly from diesel and gasoline exhausts of heavy vehicles. The general state of air pollutions appears not to have been improved, suggesting the difficulty in resolving air pollution issues. On the other hand, a current problem specific to ethanol-fuel is the aldehydes or other carcinogenic components in exhaust. Peak formaldehyde concentration, for example, have been reported to have reached 159 ppb in SPMA, which may be one of the highest levels shown in ambient air.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollution↗
PubMed1990

Role of adrenergic activity in ischemic brain edema.

Thirty male Wistar rats, weighing 200 to 300 g, were used for this study. During a 3- to 4-min period, 300 micrograms of 6-OHDA was injected stereotactically into the right lateral ventricle. The same amount of saline was injected into the ventricle for the control group. Seven days after this procedure, the right common carotid was occluded with a clip and 4 to 6 ml of blood was removed from the external jugular vein to reduce the blood pressure. The clip was removed in 2 hr, and blood flow was maintained for 1 hr. The SG of cerebral tissue was measured according to the method of Marmarou et al. The disruption of BBB was examined by Evans blue injection, and the brain tissue was also examined by electron microscopy. Rats with 6-OHDA treatment had brain edema although the control group had no edema. We suggest that the depletion of brain NA could cause a disturbance in cerebral microvascular tone and could make cerebral blood vessels more vulnerable to the decreased CBF when followed by restoration of the blood flow.

Animals↗
PubMed1990

[Atypical computed tomographic appearance of herpes simplex encephalitis].

In cases of herpes simplex encephalitis, a low density lesion in the temporal lobe is a common CT finding, whereas hemorrhagic lesion is rarely observed on CT in this disorder despite the frequent occurrence on pathologic studies. Two cases of hemorrhagic lesion observed on CT in herpes simplex encephalitis are reported, and atypical CT findings of herpes simplex encephalitis is discussed.

Adult↗
PubMed1990

[Experimental brain tumor in adult mongrel cat].

Small animal models such as the rat have serious limitations for multiple human scale instrumentation, surgical manipulations, and computerized tomographic (CT) evaluations, so that large animal models are required for the study using them. Although brain tumors induced with Rous sarcoma virus in neonatal beagle or adult monkey had been reported, these animals are very expensive ones for tumor research. A major drawback of virally induced brain tumor model is, moreover, the need for specialized viral facilities and safety precautions for laboratory personnel. In this paper, a cat glioma model implanted with C6 glioma cells derived from rats injected with N-nitrosomethylurea is reported. For an implantation dose of 5 x 10(5) cells/50 microliters, C6 glioma cells were suspended in modified Eagle medium supplemented with 10% fetal bovine serum and 0.5% agar. Twenty adult mongrel cats were injected with 5 x 10(5) C6 glioma cells intracerebrally. Implanted cats had brain tumors of about 10 mm in diameter with a yield of 80%. The mean survival was about 3 weeks after implantation. Tumors developed as spheroidal, hemorrhagic masses with central areas of necrosis and peripheral edema. They were located within the parenchyma of the implanted region. This tumor possessed many of the histological and radiological characteristics of human glioblastoma such as the following: Areas of hemorrhage and necrosis surrounded by pseudopallisading were observed within the tumor consisting of spindle-shaped cells with pleomorphic nuclei. A mass lesion with ring or garland-like enhancement surrounded by brain edema was shown on the CT scans.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Seizures induced by movement].

Three cases with seizures induced by movement are presented. These patients were a 24-year-old man, a 15-year-old girl and a 15-year-old boy respectively. In each case, the onset began at the age of thirteen. The following characteristics were observed in all cases. The attacks were precipitated by sudden initiation of voluntary movement after rest. The attacks were brought on, for instance, by running quickly from a standing position, and were characterized by tonic spasm or choreoathetotic movement of unilateral extremities. They lasted only 5 - 10 seconds, without loss of consciousness and occurred up to ten times daily. Between the attacks there were no abnormalities. Neurological examination and laboratory findings were all negative. EEG at rest showed normal findings in two cases and abnormality in one case. Cerebral angiograms did not show any abnormalities in any of the cases. On CT scans and MRI, mild dilatation of lateral ventricles was observed in one case. One of these three cases was familial. Concerning treatment, carbamazepine was the most effective means to inhibit the attacks in all three cases. Seizures induced by movement may suggest moyamoya disease to neurosurgeons who are not familiar with this disease, so it is important to be able to recognize this disease when it is encountered.

Adolescent↗
PubMed1989

Magnetic resonance imaging of embolism from intracranial aneurysms.

Two patients with embolism from unruptured intracranial aneurysms are reported. These patients experienced cerebral ischemic attacks at the ages of 10 and 64 years, respectively. Angiography revealed normal extracranial vessels and middle cerebral artery aneurysms. Preoperative magnetic resonance imaging showed intraaneurysmal clots and cerebral infarcts distal to the aneurysms. Aneurysmal neck clipping was carried out on the young patient. In the other case, the aneurysmal sac was excised, the intraluminal clot was removed, and the neck was closed with nylon sutures. These are the first cases of embolism from unruptured aneurysms in which magnetic resonance imaging revealed intraaneurysmal clots and cerebral infarcts distal to the aneurysms.

Aged↗
PubMed1989

Effect of flunarizine on arterial thrombosis after endarterectomy in rats.

Unilateral carotid endarterectomy was performed microsurgically in 60 rats. The effects of perioperative administration of aspirin and flunarizine, a Ca2+ entry blocker, on thrombus formation were examined 24 hours after endarterectomy. An untreated group of endarterectomized rats served as controls. Platelet adhesion, blood cells, and fibrin cords were observed at the cut edge of the intima as well as in the endarterectomized area in all three groups. However, these findings were significantly more extensive in the control group than in the drug-treated groups. Flunarizine was as effective as aspirin in inhibiting platelet adhesion and fibrin cord formation. Both drugs significantly increased the patency rate after carotid endarterectomy.

Animals↗
PubMed1988

[Primary intracranial malignant melanoma associated with nevus of Ota: a case report].

A case of intracranial malignant melanoma associated with nevus of Ota is presented. A 77-year-old man was admitted to the department of neurosurgery, Fukui Medical School on June, 1985 because of developing disturbed consciousness. The physical examination on admission revealed pigmented lesion diagnostic of the nevus of Ota, anisocoria (R greater than L) and left hemiparesis. Computed tomographic (CT) scans demonstrated a high density mass in the left temporal lobe and the mass was homogenously enhanced after the injection of contrast agent. Left common carotid angiogram showed elevation of the middle cerebral artery and a slight vascular blush. Subtotal removal of the dark-colored tumor within the left temporal lobe and biopsy of the nevus were performed. Histopathological examination of the tumor revealed malignant melanoma and that of the skin biopsy was consistent with a nevus of Ota. Postoperatively DTIC, ACNU and vincristine were administered intravenously but the patient died three weeks after operation. At autopsy, widespread black pigmentation of the leptomeninges, communicating with the pigmented tumor in the left temporal lobe, covered the base of the brain and spinal cord. No melanoma was found outside the central nervous system. Primary intracranial melanoma associated with nevus of Ota is rare and only 6 cases have been reported in the literature. In this paper, primary intracranial melanoma associated with nevus of Ota and some other subjects are discussed.

Aged↗
PubMed1988

[Tissue culture study of meningioma and hemangiopericytoma].

Intracranial meningioma cells and hemangiopericytoma cells were cultured in vitro for immunohistological and ultrastructural study. Anti-vimentin, desmin, actin, alpha-actinin and laminin monoclonal antibodies were applied for immunohistological examination. Three dimension culture cells in collagen gel were examined by electron microscopy for ultrastructural studies. Cultured meningioma cells and hemangiopericytoma cells were positive for anti-vimentin stain, while desmin, actin, alpha-actinin were positive in only hemangiopericytoma cells. The culture morphology of these two cells was same in light microscopic study except for the whorl formation in meningioma cells. Reconstruction of intercellular junctions such as desmosomes and junctional complexes were common in cultured meningioma cells but seldom in hemangiopericytoma cells. Hemangiopericytoma cells continued to have prominent intracytoplasmic intermediate filaments and microfilaments forming dense bodies in culture. These results suggest that intracranial hemangiopericytoma has something in common with smooth muscle cell and fibroblast cells which forms the vascular and perivascular tissues, and it is distinguishable from meningioma.

Aged↗
PubMed1987

The effects of local intraparenchymal pentobarbital on intracranial hypertension following experimental subarachnoid hemorrhage.

Barbiturates are often utilized clinically in circumstances in which elevated intracranial pressure is expected. In this study, the mechanism of action of barbiturates was examined in dogs with intracranial hypertension induced by injecting autogenous incubated blood into the chiasmatic cistern. Intracranial pressure and systemic blood pressure were continuously monitored. A single bilateral administration of powdered pentobarbital (2 mg and 0.4 mg) in experimental animals and solid d-glucose (2 mg) in control animals was given into the posterior hypothalamus, pontine reticular formation, or medullary reticular formation when intracranial pressure reached 20-30 mmHg after the blood injection--usually in 3-6 h. The increased intracranial pressure following the experimental subarachnoid hemorrhage was always associated with either intracranial pressure irregularities or concomitant blood pressure variations, suggesting the presence of vasomotor instability. Administration of both 2 mg and 0.4 mg of pentobarbital into the medulla caused a significant (P less than 0.01) decrease of the intracranial pressure to 44 and 65% of control and stabilization of the intracranial pressure irregularities, whereas pentobarbital given at the other sites did not. The blood pressure was also decreased significantly (P less than 0.01) to 80 and 88% of control and the blood pressure variations were stabilized in animals after administration of pentobarbital into the medulla, whereas in those given pentobarbital at the other sites, it was not. The results suggest that, in the presence of elevated intracranial pressure following experimental subarachnoid hemorrhage, the mechanisms of action of barbiturates in reducing the intracranial pressure may result from alleviation of cerebral vasomotor instability by depression of the vasomotor center of the medulla.

Animals↗