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Biomedical subjects

N Yasui

Publications and source records attributed to N Yasui.

At least 217 records · Page 12Linked to original sources
PubMed1989

[Vascular responses in cerebrovascular "Moyamoya" disease--evaluated by positron emission tomography].

We investigated cerebral blood flow and metabolism, and cerebral vascular response in 9 patients with cerebrovascular Moyamoya disease or unilateral Moyamoya phenomenon using positron emission tomography (PET). The subjects consisted of 5 men and 4 women, and were from 9 to 60 years old. Five patients had bilateral occlusion in the carotid fork with Moyamoya vessels (fulfilled the criteria of cerebrovascular Moyamoya disease), and four patients had unilateral Moyamoya phenomenon. The PET scanner used was the HEADTOME III, of which spatial resolution in clinical use was 10 mm full width at half-maximum (FWHM) in the image plane. Cerebral blood flow (CBF), cerebral metabolic rate of oxygen (CMRO2), cerebral oxygen extraction fraction (OEF), and cerebral blood volume (CBV) were measured in resting state by the 15O-labelled gases steady state method in every patient and 22 normal controls (17 men and 5 women, and from 26 to 64 years old). Consecutively cerebral vascular responses were measured by H215O autoradiographic method in resting state, hypercapnia, hypocapnia, and hypertension. Forced hypercapnia, hypocapnia, and hypertension were achieved by 7% CO2 inhalation, hyperventilation, and venous infusion of angiotensin II, respectively. CMRO2 of the whole brain was significantly lower in patients than in normal controls (p less than 0.05), and CBV of the lentiform nucleus significantly increased in patients (p less than 0.01). This reflected Moyamoya vessels in the basal ganglionic regions. In 3 of 5 patients with bilateral Moyamoya vessels, CBF and CMRO2 in the symptomatic cerebral hemisphere were lower than that in the nonsymptomatic hemisphere.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

[Repair of rabbit articular surfaces with allografts of chondrocytes embedded in collagen gels].

In an attempt to restore articular cartilage, allogeneic articular chondrocytes embedded in collagen gels were transplanted onto full-thickness defects in rabbit articular cartilage. Within 24 weeks after the transplantation, the defects were filled with hyaline cartilage, specifically synthesizing type II collagen. These chondrocytes were autoradiographically proven to be originated from the originally transplanted chondrocytes. As histologically assessed, success rate was about 80%, a marked improvement over the results (40% success rate) in previous studies reporting chondrocyte transplantation without collagen gels. On the other hand, the defects without chondrocyte transplantation healed with fibrocartilaginous tissue more than 24 weeks after treatment. Immunological enhancement induced by transplanted allogeneic chondrocytes or collagen was not significant for eight weeks after treatment, so far as shown by both direct and indirect blastformation reactions. Thus, allogeneic transplantation of isolated chondrocytes embedded in collagen gels appears to be one of the most promising methods for the restoration of articular cartilage.

Animals↗
PubMed1988

Computerized monitoring system in neurosurgical intensive care.

A computerized monitoring and analyzing system for neurosurgical intensive care has been developed. The system continuously monitors the function of the central nervous, cardiovascular and respiratory systems. Correlation between such parameters can be analyzed automatically. The electroencephalogram (EEG) and intracranial pressure (ICP) were monitored as parameters for CNS function and condition. The cardiovascular and respiratory systems were monitored by heart rate, systemic blood pressure, central venous pressure, pulmonary arterial pressure, respiratory rate, and expiratory O2 and CO2 pressures. Body temperature was also monitored continuously. Sequential changes of those parameters were displayed on time-dependent trend graphs, and correlations between each parameter were automatically analyzed by linear regression equations. The clinical applicability of the system was demonstrated in the postoperative treatment of cerebral vasospasm following subarachnoid hemorrhage due to ruptured intracranial aneurysm. In such a case, EEG slowing was observed in this system prior to clinical deterioration, and had a correlation with a decrease of pulmonary arterial pressure. Thus, the necessity for restoration of intravascular volume was realized before clinical deterioration progressed.

Aged↗
PubMed1988

Bone lengthening in rabbits by callus distraction. The role of periosteum and endosteum.

The histology and mechanics of leg lengthening by callus distraction were studied in 27 growing rabbits. Tibial diaphyses were subjected to subperiosteal osteotomy, held in a neutral position for 10 days and then slowly distracted at 0.25 mm/12 hours, using a dynamic external fixator. Radiographs showed that the gap became filled with callus having three distinct zones. Elongation appeared to occur in a central radiolucent zone; this was bounded by two sclerotic zones. Histologically, the radiolucent zone consisted of longitudinally arranged cartilage and fibrous tissue while the sclerotic zones were formed by fine cancellous bone. New bone occasionally contained islands of cartilage, suggesting it had been formed by endochondral ossification. After completion of distraction, the two sclerotic zones fused, shrank and were eventually absorbed, leaving tubular bone with a new cortex. When the periosteum had been removed at the operation, callus formation was markedly disturbed and there was failure of bone lengthening. Scraping of endosteum, in contrast, did not have a pronounced effect. These results suggest that the preservation of periosteum is essential if bone lengthening by callus distraction is to succeed, and that preservation of the periosteum is more important than careful corticotomy.

Animals↗
PubMed1988

A case of short metatarsal bones lengthened by callus distraction.

Bilateral congenitally short fourth metatarsal bones were osteotomized subperiosteally, held in neutral position for 3 weeks by a small external fixator, and then subjected to slow axial distraction (0.25 mm/12h). The overall treatment time was 11 weeks, and the final increase in length was 14 mm for the left and 12 mm for the right metatarsal bone.

Adolescent↗
PubMed1988

[Midbrain arteriovenous malformation causing bilateral total ophthalmoplegia as an initial ocular symptom--a case report].

A 61-year-old woman is presented with a bilateral total ophthalmoplegia as an initial ocular symptom, caused by a midbrain hematoma. She complained of acute headache, nausea, vomiting and bilateral closure of her eyelids. Examination on admission showed meningeal irritation; mild consciousness disturbance; bilateral total ophthalmoplegia; left hemiparesis; ataxia in all extremities, more marked to the left. Computed tomography demonstrated a small hematoma in the midbrain tegmentum. Angiography demonstrated midbrain arteriovenous malformation, and she was treated conservatively. Abduction of both eyes and adduction of the left eye appeared on the next day of the ictus, and after that, improved gradually. Left ptosis had improved since one week after the ictus. Light reflex of the left pupil had seen 5 days after the ictus. At the same time, the left pupil revealed an oval-shape. Right internal ophthalmoplegia continued to exist. One year later, the right eye deviated externally, and the left deviated inferio-medially. Abduction of both eyes was normal. Infraduction of both eyes was seen, but limited on the left. Upgaze paresis remained unchanged, and adduction of the right eye was absent. Adduction of the left eye showed almost full recovery. There was right complete ptosis, but left ptosis became indefinite. These ocular findings indicated typical right oculomotor paresis plus superior rectus paresis of the left eye, which suggested a destructive lesion in the right oculomotor nucleus. Also, her left extremities showed a hemiparesis as a pyramidal tract sign (Weber's syndrome) and an ataxia as a cerebellar sign (Claude's syndrome).(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebellar Ataxia↗