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Biomedical subjects

O Hirai

Publications and source records attributed to O Hirai.

52 records · Page 3Linked to original sources
PubMed1984

Microheterogeneity of brain dopamine in the experimental acute cerebral ischaemia.

In order to reveal the correlation of energy failure and neurotransmitter metabolism in the acute stage of incomplete cerebral ischaemia, the change of NADH (reduced form of nicotinamide adenine dinucleotide) and brain dopamine was studied histochemically using the same specimen on the unilateral carotid ligation of mongolian gerbils. The severity of clinical symptoms was well correlated with the extent and intensity of NADH fluorescence. Dopamine in the caudate nucleus on the ligated side decreased heterogeneously shortly after the cerebral ischaemia. Preservation of dopamine was noted around the small vessels with thick walls. Thus, heterogeneity of dopamine decrease appears to be closely related to the structure of microvasculature. It was seen in areas of heterogeneously increased NADH, but also in areas of its homogeneous increase within 5 to 60 min after carotid ligation. This microheterogeneity of brain dopamine may be due to the difference of perfusion pressure at the microcirculation in the acute stage of incomplete cerebral ischaemia.

Animals↗
PubMed1984

Epidural pulse waveform as an indicator of intracranial pressure dynamics.

With an increase in intracranial pressure during epidural balloon inflation, epidural pulse waveform, which is polyphasic under normal conditions, becomes monotonous at about 30 mmHg. This change in waveform is considered closely related to the apparent increase in arterial driving pressure to the brain and to a disturbance of venous outflow. When cerebral vasodilatation is prominent, the waveform becomes monotonous at a significantly lower intracranial pressure. These findings correlate well with the results of spectral analysis of the pulse wave. The usefulness of change in epidural pulse waveform, which can indicate an alteration of intracranial pressure dynamics in a relatively low pressure range, is discussed with comparison to other techniques used to determine intracranial pressure dynamics.

Animals↗
PubMed1984

[Regional change of brain energy metabolism and catecholamine in the early stage of experimental cerebral ischemia--histochemical study].

Ischemic change of cerebral energy metabolism and catecholamine have already been discussed largely using biochemical quantitative assay. However, regional change and their correlation are not well understood. In the present study, the ischemic regional change of cerebral energy metabolism and catecholamine were investigated in gerbils and histochemical method. Adult either sex mongolian gerbils, weighing 50-100 g, were anesthetized with ether and the left carotid artery was ligated. After observation of clinical symptoms, the brain was frozen in situ by pouring liquid N2 after 30 min and 60 min of ischemic insult. The frozen brain was sectioned with precooled saw in the coronal plane. The brain section were placed in liquid N2 bath and illuminated with 366 nm light (UV) from a 200 watt mercury lamp and Corning filter 5840. NADH fluorescence was recorded photographically through Corning filter 3387 and 5562. Also UV reflectance was recorded through Corning filter 5840 to observe quenching effect of hemoglobin. Regional change of catecholamine was observed in the same frozen brain processed with Falck-Hillarp method. According to neurological abnormalities following left carotid ligation, animals were divided into three groups; symptomatic, borderline and asymptomatic. The intensity and distribution of tissue NADH fluorescence were closely correlated to the clinical symptoms. In the symptomatic group, both in 30 min and 60 min of ischemia, homogeneously and markedly increased fluorescence was observed in the ipsilateral temporal cortex, caudate nucleus, hypothalamus and dorsolateral thalamus. Columnar mild increase of NADH fluorescence was seen in the ipsilateral parietal cortex.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1982

The central anti-serotonin activity of zotepine, a new neuroleptic, in rats.

2-Chloro-11-(2-dimethyl-aminoethoxy) dibenzo [b, f] thiepin (zotepine) is a new neuroleptic drug which is structurally different from known neuroleptics. Zotepine, chlorpromazine, propericiazine, and cyproheptadine inhibited hyperthermia induced by dosing with fenfluramine in rats in a warm environment (26-28 degrees C). Fenfluramine is known to induce hyperthermia by mediation of central serotonin. Zotepine had a 10 times or greater potency than chlorpromazine, propericiazine and cyproheptadine in inhibiting the hyperthermia. Thioridazine did not inhibit the hyperthermia, whereas haloperidol accelerated the hyperthermia. Zotepine was also the most potent inhibitor of 3H-serotonin binding to rat cortical synaptosomes in vitro. However, cyproheptadine had the strongest anti-serotonin activity in rat fundus preparations, while zotepine and other neuroleptics showed the same order of potency. These results showed that zotepine is a unique neuroleptic with potent central anti-serotonin activity. The central anti-serotonin activity of zotepine is discussed in connection with its lesser extrapyramidal side effects in humans.

Animals↗
PubMed1982

[Intracranial pressure pulse waveform: considerations about its origin and methods of estimating intracranial pressure dynamics].

Epidural pulse waveform is important as an indicator of intracranial pressure (ICP) dynamics. In this study, the origin of epidural pulse and the clinical implication of its waveform were investigated, using anesthetized artificially ventilated dogs. For this purpose, a cortical artery and a vein were cannulated, and the pressures were recorded simultaneously with epidural pressure (EDP), epidural pulse waveform (EDP-WF), systemic arterial pressure measured in a carotid artery (SAP), central venous pressure (CVP) and electrocardiogram. EDP-WF is composed of several initial peaks and a small delayed peak on the descending limb. The former peaks were slightly delayed from the SAP pulse and were synchronous with the cortical arterial pulse. The latter peak was synchronous with the atrial "a" wave on CVP, but not with the cortical venous pulse. Moreover, the cortical venous pulse was quite similar to EDP-WF. These findings indicate that the pulsation of the brain may be generated by the pulsatile arterial blood flow into the brain, which also affected the pulsation of the cortical vein. The latter peak which was considered to be of venous origin may reflect the dynamics of venules in the brain, not of the cortical vein. Increase of ICP by constant inflation of the epidural balloon or inhalation of CO2 cause EDP-WF monotonous. It is possible that the transmission of arterial pulse into the brain was augmented because of the tightness of the brain or decrease of cerebral vascular tone, although the cortical arterial pressure was not significantly changed or was even slightly decreased. Using a bolus injection technique, the change of EDP-WF in cats was compared with volume-pressure response (VPR) and pulse pressure (PP) which are reported to be good indicators for ICP dynamics. At about 30mmHg, EDP-WF became monotonous while VPR or PP showed only linear relationships with EDP up to 50 to 60 mmHg. Therefore EDP-WF may provide useful information about ICP dynamics in a relatively lower pressure range which could not be detected by VPR or PP study.

Animals↗
PubMed1981

Prepontine epithelium-lined cyst. Case report.

A 30-year-old woman presented with recurrent episodes of severe headache associated with visual disturbances. Neurological examination showed minimal neurological defects. Angiography, computerized tomography, and radioisotope cisternography revealed a large cyst in the prepontine region, which did not communicate with either the subarachnoid space or the ventricular system. Histologically, the cyst was lined by columnar and/or cuboidal cells, which contained materials positive on periodic acid-Schiff staining. Ultrastructurally, there were two types of cells, ciliated and noncillated. Characteristic findings were continuous basement membrane, microvilli covered with electron-dense material, several intercellular junctional devices, and an open intercellular space which was occasionally filled with a migrating cell. These findings would support the view that the epithelial cyst with such features was derived from endodermal tissues rather than from neuroepithelium. Electron microscopic examination is indispensable in making a correct diagnosis of intracranial cysts.

Adult↗