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Biomedical subjects

T Azumi

Publications and source records attributed to T Azumi.

At least 37 records · Page 2Linked to original sources
PubMed1981

Biochemical mechanism of infarct size reduction by pyruvate.

We have explored the biochemical mechanism of the infarct size reduction found after intracoronary pyruvate infusion. Using the double infarct model, we simultaneously produced in nine dogs a control- and a therapy-infarct and compared the infarct sizes in each dog after 90 min of occlusion and 90 min of reflow. Intracoronary pyruvate reached the therapy infarct only by way of collaterals but had no access to the control infarct. Tissue levels of reduced nicotinamide dinucleotide (NADH) were measured in control-normal-, therapy-normal-, control-ischaemic-and pyruvate-treated ischaemic areas. In all nine dogs we found a significant reduction in infarct size and NADH levels in the pyruvate-treated areas. Therapy-normal NADH levels fell to 30+/-10% (mean+/-SD) of control-normal levels and therapy-ischaemic NADH levels to 26+/-17% of control-ischaemic levels. We assumed that the infused pyruvate was converted to lactate and at the same time NAD was generated from NADH. Thereby the blockage of glyceraldehyde-3-phosphate-dehydrogenase (GAPDH) by high NADH/NAD-ratios in ischaemic myocardium should be moderated, and ATP production by anaerobic glycolysis stimulated. These small amounts of ATP may be sufficient to guarantee membrane integrity over 90 min of ischaemia and so diminish its harmful effects on the myocardium.

Adenosine Triphosphate↗
PubMed1981

Evaluation by patients of surgical orthodontic correction of skeletal Class III malocclusion: survey of 41 patients.

To assess whether surgical procedures have fulfilled patients' expectations, questionnaires were sent to 41 patients who had undergone surgical-orthodontic correction of skeletal Class III malocclusions. Ninety per cent of the patients answered that they were satisfied with the results in regard to their chief problems and 85% had improved masticatory function. A favorable change in appearance was recognized by 24 patients, whereas 15 patients noticed no major changes, and two were displeased with the changes. Patients' expectations were not always satisfied despite evident improvement by objective standards. Factors affecting their satisfaction with the results of the surgery are discussed.

Adolescent↗
PubMed1981

Malignant ameloblastoma with metastasis to the skull: report of case.

An unusual case of ameloblastoma that underwent malignant change and metastasis during recurrence is described. The primary tumor of the mandible and two independent recurrent lesions found in the base of the coronoid process and in the mandibular notch were cystic ameloblastoma of follicular type, with no histological evidence off malignancy. The second recurrence developed in the soft tissues on the medial aspect of the ascending ramus and consisted of a large solid tumor mass with poorly differentiated ameloblastoma cells, which were seen clustered in blood vessels in close apposition to tumor nests. Apparently these metastasized to the temporal bone in five months. The metastatic tumor was composed of atypical follicles packed with undifferentiated hyperchromatic cells with nuclear atypia and abundant mitoses. The histological diagnosis was malignant ameloblastoma. The cerebral lesion that developed in the skull base, possibly by direct extension of the second recurrent tumor, was also regarded as malignant because of its rapidity and aggressive growth and its high sensitivity to radiotherapy.

Adult↗
PubMed1981

Effects of combination treatment with vitamins E and C on chloasma and pigmented contact dermatitis. A double blind controlled clinical trial.

A multi-clinical double-blind study on therapeutic effect of combination preparation of vitamins E and C was undertaken in comparison with single preparation of vitamin E and vitamin C in the treatment of chloasma or pigmented contact dermatitis (PCD). Combination treatment resulted in significantly better clinical improvement than vitamin C alone in both diseases. Objective data compiled from color difference measurements and color photographs revealed significantly better results with combination treatment in chloasma than vitamin C alone and, in PCD, than vitamin E or C alone. Differences in skin luminosity between hyperpigmented and normal areas significantly decreased in all three groups, with the combination group producing the most significant change. The total serum lipoperoxide level and its ratio to total serum lipids tended to decline in the combination group, and decreased significantly in vitamin E group. The sebum lipoperoxide level decreased significantly only in the combination group (EC).

Ascorbic Acid↗
PubMed1980

An electrographic study on the functional capacity of the coronary collateral circulation in dogs with chronic coronary occlusion.

The functional capacity of coronary collaterals was investigated under resting and stress conditions in 15 dogs with chronic occlusion of the anterior descending coronary artery. ST-elevation in epicardial and intramyocardial electrograms was used for assessing the degree of regional myocardial ischemia. In resting condition, epicardial and intramyocardial electrograms from collateral, intermediate and circumflex areas revealed no significant ischemic changes. In 6 of 15 dogs in which atrial pacing was performed, ST-elevation appeared in electrograms from collateral and intermediate areas. In another 9 dogs, pacing tachycardia produced no significant changes in all electrograms. In these dogs more than 50% constriction of the donor coronary artery was necessary to induce ST-elevation in electrogram from collateral area. These findings indicate that the coronary collateral vessels in dog play beneficial role to prevent the myocardium from ischemic injury under stress condition, although their functional capacity is not comparable to that of normal coronary artery.

Animals↗
PubMed1980

Pathologic fracture of the mandible resulting from osteomyelitis: report of cases.

Two cases of pathologic fracture of the mandible resulting from chronic osteomyelitis are described. The first case was treated successfully by antibiotic therapy followed by resection of the affected bone and iliac bone grafting after six months of follow-up care. In the second case, a patient with a history of diabetes mellitus, a fracture of the condyloid process occurred because of extension of the Actinomyces infection after extraction of the third molar. Because antibiotics failed to prevent exacerbation of the disease, the patient was given human gamma globulin. Then, all the signs of inflammation disappeared gradually with no evidence of recurrence for more than a year. There was no spontaneous bony healing of the fractured site.

Adult↗
PubMed1979

Negative dromotropic effect of diazepam on the AV node of dog heart in situ.

Effect of diazepam on the AV nodal conductivity was studied using a direct perfusion technique of the canine AV node artery in situ. As compared to acetylcholine which induced a rapid onset of third degree AV block with prompt recovery, diazepam injected into the AV node artery in doses from 300 micrograms to 3 mg elicited first to third degree AV blocks of longer duration following gradual prolongation of PR interval. The response was not affected by bilateral vagotomy and sympathectomy. Pretreatment of the AV node with hexamethonium or atropine also failed to modify the diazepam-induced AV blocks. Thus, diazepam seemed to suppress conductivity of the AV node by a direct action. The AV nodal tachycardia induced by infusion of norepinephrine was readily antagonized by a single injection of diazepam, but norepinephrine failed to reverse the AV block induced by diazepam infusion.

Acetylcholine↗
PubMed1979

Negative and positive chronotropic effects of procaine on the canine SA node in situ.

Effect of procaine on the SA node of the dog heart was studied in situ using a selective perfusion technique of the SA node artery. Procaine in doses from 100 mug to 1 mg produced a sinus depression followed by a prolonged phase of the increased heart rate. The depression became more prominent with increasing the dose. The threshold dose for inducing the tachycardiac response was lower, but the sinus acceleration was not proportional to the dose. The initial depression was not affected by atropine, whereas the occurrence of the stimulatory phase was inhibited by prior administration of propranolol or tetrodotoxin into the SA node artery or in the reserpine-treated dogs. The results indicate that the biphasic response is induced by a direct negative chronotropic action of procaine on the SA node and by an indirect effect mediated by an interaction with the postganglionic adrenergic nerves.

Animals↗
PubMed1978

An experimental study on the role of coronary collateral development in preservation and improvement of contractile force in the ischemic myocardium.

Attempts have been made to demonstrate that the presence of coronary collateral development can preserve and improve the regional contractile force in the ischemic myocardium. Studies were carried out in dogs with developed collaterals and in control dogs. Contractile force was measured with strain-gauge sutured onto the ischemic and the border areas of the myocardium. After ligation of the anterior descending coronary artery, an augmentation of coronary collateral flow via the left circumflex artery was carried out by means of infusion pump up to two and a half fold level. In dogs with developed collaterals, contractile force decreased by 57.6 +/- 11.1% (p less than 0.01) in the ischemic area and 27.2 +/- 5.4% (p less than 0.01) in the border area after coronary ligation. The marked recovery of contractile force up to 63.5 +/- 20.4% (p less than 0.05) of control level in the ischemic area and 70.4 +/- 20.4% (p less than 0.01) in the border area was observed by the augmentation. In control dogs, however, contractile force decreased by 93.2 +/- 17.2% (p less than 0.01) in the ischemic area and 24.6 +/- 5.5% (p less than 0.01) in the border area after the ligation. The augmentation of coronary flow did not recover the depressed contractile force in both areas. These results indicated that the beneficial effect was observed only when the ischemic area was supplied by developed collaterals and closely correlated with the extent of coronary collateral development.

Animals↗
PubMed1978

Effects of graded coronary constriction on regional oxygen and carbon dioxide tensions in outer and inner layers of the canine myocardium.

This study was undertaken to investigate the effects of graded coronary constriction on regional gas tensions of the myocardium. In 12 open chest dogs, tissue carbon dioxide (PtCO2) and oxygen (PtO2) tensions were measured simultaneously in outer and inner layers of the myocardium using a mass spectrometer. In normal condition, higher PtO2 and lower PtCO2 were observed in outer layer than in inner layer. With application of coronary constriction, increase in PtCO2 and decrease in PtO2 were observed in both layers of the myocardium, but the response to the ischemic stimuli by applying coronary constriction in inner layer was different from that in outer layer. Severe coronary constriction, more than 90% in its diameter, was necessary to produce significant changes in both gas tensions in both layers of the myocardium. Decrease in PtO2 was found in the condition of less severe coronary constriction and to be greater in inner layer than in outer layer of the myocardium. In terms of the changes in PtCO2, inner layer was also more susceptible to the ischemic stimuli than outer layer. The greater and earlier elevation of PtCO2 in inner layer than in outer layer is regarded as one of the possible mechanisms of the reduction of myocardial contraction in the early stage of myocardial ischemia.

Animals↗
PubMed1978

Mechanism of positive chronotropic response of the canine SA node to selective administration of ketamine.

Mechanism for induction of the positive chronotropic effect of ketamine was studied in vivo using a selective perfusion technique of the canine SA node artery. In the reserpinized dogs in which tyramine responsiveness could be restored with norepinephrine, an injection of ketamine induced no sinus acceleration, while its prior administration to norepinephrine suppressed the response to tyramine. In the tetrodotoxin treated preparation in which the effect of electrical stimulation of the vagus and the stellate ganglion was abolished, tyramine produced an increase of sinus rate as usual, but the induction of sinus tachycardia by cocaine and ketamine was completely blocked. The results indicated that the positive chronotropic response of the SA node to ketamine might be induced by an inhibition of the norepinephrine uptake at the adrenergic nerve endings in a cocaine-like manner.

Animals↗
PubMed1977

Biphasic response of the SA node of the dog heart in vivo to selective administration of ketamine.

Effect of ketamine on the SA node of the dog heart was studied in vivo using a selective perfusion technique of the SA node artery. Injections of ketamine in doses from 100 microgram to 3 mg into the artery produced a depression of the SA nodal activity by a direct action. This depression was followed by the sudden appearance of a stimulatory phase. Bilateral vagotomy and sympathectomy or prior administration of a ganglion blocker failed to inhibit the occurrence of the ketamine-induced tachycardia, while it was completely abolished in the reserpinized dogs or by a prior injection of a beta-blocking agent into the SA node artery. This may indicate that an activation of the peripheral adrenergic mechanism plays an important role in the induction of the excitatory effect of ketamine injected in the SA node artery.

Animals↗