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Biomedical subjects

T Sakamoto

Publications and source records attributed to T Sakamoto.

At least 1,189 records · Page 66Linked to original sources
PubMed1980

[Correlation between the thalamus EEG and rCBF in the thalamus infarction in the dogs (author's transl)].

We have made an investigation of the correlation between the changes in thalamic EEG and rCBF immediately following occlusion 4 arteries at the base of the brain using thalamic infarction model with 38 dogs. Changes in EEG patterns due to vascular occlusion were divided into 4 grades. A tendency was found for decreases in rCBF to be greater the more marked were the EEG changes. Animals showing mild EEG changes in which there was only slight attenuation of voltage had rCBF values roughly 63% those prior to occlusion; animals with moderate EEG changes in which there was voltage attenuation and an increase in slow wave components had rCBF values of 34%; and animals with severe EEG changes in which there was voltage attenuation and complete disappearances of fast wave components showed rCBF values of roughly 29%.

Animals↗
PubMed1979

Studies on rat liver catalase. X. Effect of hemin and an inhibitor on the translation of catalase messenger RNA1.

Rat liver catalase mRNA was translated in a rabbit reticulocyte lysates and wheat germ cell-free system in the presence or absence of hemin and/or a translational inhibitor prepared from reticulocytes, liver cells, and wheat germs. Failure to add hemin to the lysates, or the addition of a hemin-regulated translational inhibitor (HRI) to the hemin-supplemented lysates caused a repressed translation. A preparation of inhibitor from rat liver showed activity similar to that of HRI for this translating system. The translation repression by rat liver inhibitor was reversed by eIF-2 (initiation factor) or GTP, but ATP enhanced the repression. The translation of catalase mRNA in the wheat germ system was not affected by the addition of hemin. An inhibitor prepared from wheat germ extracts, as well as the rat liver inhibitor, markedly decreased the rate of translation. eIF-2, GTP, and ATP behaved in the manner described above. Catalase synthesis in a cell-free system derived from rat liver (using endogenous mRNA) was not influenced by either hemin or the inhibitor. The possibilities are discussed that the synthesis of catalase in liver cells is controlled by a translational inhibitor at the level of chain initiation, and that the formation of the inhibitor from its inactive proinhibitor is regulated by the amount of heme.

Adenosine Triphosphate↗
PubMed1979

Arrest reaction in man: motor arrest response by electrical stimulation of the deep structure of the cerebrum.

In spite of many reports of arrest reaction in animals, there are very few reports in man. During a therapeutic stereotactic operation we observed peculiar phenomena caused by electrical stimulation to the deep structure of the cerebrum. The electrical stimulation caused an interruption of counting and other motor actions, which could be resumed following release of stimuli. In almost all cases psychic confusion of memory disturbances were not observed. The head of the caudate nucleus and its adjacent white matter cause arrest reaction with the lowest threshold of 5 V; on the other hand, substantia medullaris lobi frontalis, radiatio corporis callosi and nucl. reticularis oralis of the thalamus caused arrest reaction with the highest threshold of 10--15 V. The arrest reaction that we observed is thought to be due to a direct effect on the head of the caudate nucleus, not due to secondary effects on the internal capsule and the motor fiber in the vicinity of the caudate nucleus. However, the possibility that the current spread to the motor fiber cannot be definitely ruled out.

Adult↗
PubMed1979

Hepatic bruits in malignant liver tumors.

There have been few reports concerning hepatic bruits in malignant liver tumors, especially in those other than hepatocellular carcinoma. Lately we noticed hepatic bruits in several cases of malignant liver tumors. The murmurs were confirmed by sound recordings. In cases of hepatocellular carcinoma the murmurs were continuous or continuous with late systolic accentuation. In a case of cholangiocarcinoma of the liver the murmur was continuous with late systolic accentuation and in a case of metastatic liver carcinoma it was systolic. These murmurs were considered to be caused by various mechanisms and some of them are discussed in this paper. Hepatic bruits would be a useful aid in diagnosing hepatic tumors.

Adenoma, Bile Duct↗
PubMed1979

[The effect of mannitol in preventing the development of cerebral infarction--an electron microscopical investigation (author's transl)].

We have undertaken an electron microscopical investigation of the effects of mannitol on the development of cerebral infarction using an experimental model for thalamic infarction in dogs. 1) It was found that administration of 20% mannitol (2 g/kg) prior to arterial occlusion had significantly suppressive effects upon the formation of cerebral infarction following occlusion. 2) In the control group, only one animal with 30 minutes occlusion showed no pathological changes, but, in the mannitol group, dogs with normal brain tissue were seen even after 120 minutes occlusion. 3) All of the control animals with 60 minutes occlusion showed nerve cell shrinkage, but none of the mannitol treated animals showed such changes. 4) After 180 minutes of arterial occlusion, no notable differences were found between the control and mannitol groups. In one of the mannitol treated animals, cerebral infarction was more severe than in the control group.

Animals↗
PubMed1979

[Production of infarction model in dogs by several brain arteries occlusion. Part 1: Production of hemispheric non blood supply model (author's transl)].

Experimental brain infarction in model animals should most ideally be constant in the site of occurrence, be of severity that is controllable by the occlusion time of blood flow and, moreover, be reproducible at a high rate to desired extent and severity. However, among infarction models elaborated in animals so far, only thalamus infarction model in dogs which were reported by us previously have been proven to satisfy almost all of these requirements. In experiments with these model dogs we found that an extensive infarction can be produced at a high frequency in the involved hemisphere by a transient occlusion of blood flow at such intracranial levels as the internal carotid artery, the junction of the anterior cerebral artery and ophthalmic artery, the middle cerebral artery, the origin of the segment A2 of the anterior cerebral artery, and the junction of the posterior communicating artery and posterior cerebral artery. During about one hour following the releasing of the arteries approximately 2 hours occlusion, the development of severe brain edema resulted involving the whole hemisphere on the affected side invariably in all cases. This method for experimental production of brain infarction permits to control the degree of resultant brain edema by changing the duration of occlusion of blood flow, requires simple manipulations only and ensures production of a constant lesion. With these advantage it can be anticipated to prove of great benefit in the study of postischemic brain edema.

Animals↗