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Biomedical subjects

H Yokote

Publications and source records attributed to H Yokote.

47 records · Page 3Linked to original sources
PubMed1987

Stereotactic operation for brain abscess.

Stereotactic management of brain abscess (stereotactic aspiration with external drainage) was performed in 14 patients. Fifteen abscesses in 14 patients were successfully aspirated by this method. After aspiration of the abscess, all patients underwent external drainage for an average of 14.5 days. No complications during aspiration or during external drainage (such as bleeding or infection, respectively) were encountered in our series. Ten out of 14 patients (71.4%) showed excellent prognosis, and 3 of 14 (21.4%) showed good outcome. Only one patient died after the operation, but this was due to lung cancer. Our operative results are quite satisfactory in comparison with operative results reported by other authors.

Adult↗
PubMed1987

Regulation of rCBF by intracortical vasoactive intestinal polypeptide-containing neurons. Immunohistochemical and hydrogen clearance study in rats.

The role of intracortical vasoactive intestinal polypeptide (VIP)-containing neurons in the regulation of cortical blood flow was investigated in rats by immunohistochemical and hydrogen clearance methods. Immunohistochemical studies revealed an intimate association between intracortical VIP-containing neurons and small blood vessels. Intracortical injection of a VIP solution (10(-5) M) produced significantly higher blood flow in the treated cortex (mean +/- standard error of the mean: 46.2 +/- 4.0 ml/100 gm/min) than in the untreated cortex (36.9 +/- 2.4 ml/100 gm/min). These data suggest that intracortical VIP-containing neurons produce dilatation of intracortical blood vessels.

Animals↗
PubMed1986

The distribution of adrenergic receptors in cerebral blood vessels: an autoradiographic study.

The first morphological evidence of the existence of adrenergic receptors (alpha 1, alpha 2 and beta) within the vascular walls of the central nervous system were presented using the in vitro receptor autoradiographic technique. In the rat pial arteries all three types of adrenergic receptors were demonstrated, whereas the human pial arteries failed to show significant autoradiographic grains of alpha 1 type of adrenergic receptors indicating a considerable inter-species difference in the distribution of adrenergic receptors. alpha 2 and beta receptors in human pial arteries were found not only in the arterial smooth muscle layers but also in the endothelial layers. This suggests a possibility that circulating sympathomimetic agents play some role in controlling the tone or permeability of vascular walls within the central nervous system. A distinct distribution of alpha 1 receptors in cortical layer IV where the vascular plexus was richest may suggest a relation of alpha 1 receptors and blood flow of brain parenchyma.

Animals↗
PubMed1986

A role of the central catecholamine neuron in cerebral circulation.

The effect of the central catecholaminergic neurons on the cerebral microcirculation was investigated by means of a unilateral intracerebral injection of 6-hydroxydopamine (6-OHDA) which produced the degeneration of catecholamine (CA) nerve terminals. Subsequent observation with CA histofluorescence revealed an absence of CA fibers in the vicinity of the 6-OHDA injection site. A significant increase in regional cerebral blood flow (rCBF), measured by the hydrogen clearance method, was demonstrated in the CA-depleted cortex under normocapnia as compared with rCBF in the control cortex (CA-depleted cortex 47.0 +/- 2.8 ml/100 gm/min; control cortex 38.5 +/- 3.5 ml/100 gm/min; p less than 0.005). The increased rCBF in the cortex treated with 6-OHDA was suppressed by the iontophoretic replacement of noradrenaline (NA) to the CA-depleted cortex. An iontophoretic replacement of 10(-5) M dopamine (DA) mildly suppressed the increased rCBF in the 6-OHDA-treated cortex. The CO2 reactivity in the CA-depleted cortex was significantly lower than that of the control cortex (CA-depleted cortex 2.13% +/- 0.6%/mm Hg; control cortex 3.53% +/- 0.70%/mm Hg). No change was noticeable in the cerebral glucose metabolism in the CA-depleted cortex in an investigation based on tritiated (3H)-deoxyglucose uptake. It is suggested that the 6-OHDA-induced change in cerebral blood flow (CBF) is not secondary to alterations in cerebral metabolic rate, and that the central NA neuron system innervating intraparenchymal blood vessels regulates CBF through a direct vasoconstrictive effect on the cerebral blood vessels. The central DA neuron system may modulate the cerebral circulation as a mild vasoconstrictor.

Animals↗
PubMed1985

Chronic subdural hematoma after open heart surgery.

Three cases of chronic subdural hematoma after open heart surgery are reported. In all cases, computed tomography scans revealed subdural accumulations of high density after cardiac surgery. The high-density areas changed into isodensity or low density with mass effect within 2 or 3 weeks. Anticoagulant (heparin) and a tearing of bridging veins after a rapid change of the brain volume by administration of mannitol can be a cause of chronic subdural hematoma. Forty-five to 60 mL of liquefied hematoma was aspirated and the outer membrane of the hematoma cavity was recognized by a trepanation.

Adult↗
PubMed1985

5-Hydroxytryptamine innervation of vessels in the rat cerebral cortex. Immunohistochemical findings and hydrogen clearance study of rCBF.

The role of the central 5-hydroxytryptamine (5-HT) neuron system in cerebral microcirculation of the rat was examined by immunohistochemical and hydrogen clearance methods. Immunohistochemical studies demonstrated 5-HT-immunoreactive nerve fibers along intraparenchymal blood vessels (arterioles, capillaries, and venules). Ultrastructural observation revealed that 5-HT-immunoreactive terminal boutons (0.3 to 1.0 micron in diameter) made contact with the basement membrane of the capillaries. After an intracerebral injection of 5,7-dihydroxytryptamine (5,7-DHT), a neurotoxin to the 5-HT neuron system, no 5-HT-immunoreactive nerve fibers were found around the injection site with immunohistochemical techniques. With the hydrogen clearance method, the 5,7-DHT-injected cortex showed no significant change in regional cerebral blood flow (rCBF) in the presence of normocapnia, but a significant increase in rCBF with hypercapnia, compared with the untreated cortex. These facts strongly suggest that the central 5-HT neuron system has an important role in carbon dioxide reactivity of the cerebral blood vessels.

Animals↗
PubMedDate not supplied

Antitumor effects of butyrolactone I, a selective cdc2 kinase inhibitor, on human lung cancer cell lines.

Butyrolactone I, which is a naturally occurring specific inhibitor of the cdc2 kinase family, showed antitumor effects on several non-small- and small-cell-lung cancer cell lines with IC50 values the order of 50 micrograms/ml on the former. No cross-resistance of several drug-resistant cell lines, including those with the multidrug-resistant phenotype and five cisplatin-resistant cell lines to butyrolactone I was observed. The cdc2 kinase activity of PC-14 cells was inhibited by treatment with 20 micrograms/ml butyrolactone I, a concentration comparable to the IC50 value, for 2 hours. Longer exposure to butyrolactone I (> 24 hours) reduced the cdc2 kinase protein level. Butyrolactone I arrested the cells at the G2/M phase in a concentration dependent manner. These results suggest that butyrolactone I actually acts on cdc2 kinase, rather than other cdk kinases, in PC-14 cells. Inhibition of DNA synthesis, determined by measuring thymidine uptake, occurred earlier (2 hours) after initiating exposure than the decrease in the cdc2 protein level and was concentration dependent, suggesting that butyrolactone I inhibited DN4 synthesis. Cell permeabilization by digitonin enhanced DN4 synthesis inhibition by butyrolactone I, suggesting that the permeability of the membrane to this agent was the limiting factor for its growth inhibitory effect. Many anticancer agents, such as alkylating agents and cisplatin, cause cells to accumulate at the G2/M phase of the cell cycle. We investigated whether butyrolactone I had any modulatory effect on the antitumor effects of several anticancer drugs in vitro. Butyrolactone I showed no modulatory effects on vindesine, paclitaxel, or etoposide, but exposure of PC-9 and PC-14 cells to butyrolactone I together with or prior to treatment with cisplatin reduced the cytotoxicity of the latter. Thin-layer chromatographic analysis revealed that butyrolactone I bound to cisplatin, which was a possible cause of the reduced cisplatin cytotoxicity in the presence of bytyrolactone I.

4-Butyrolactone↗