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Biomedical subjects

T Shibuya

Publications and source records attributed to T Shibuya.

At least 361 records · Page 20Linked to original sources
PubMed1985

Ventricular arrhythmia with postural dependency.

Ventricular arrhythmias associated with recumbency were noted in a 17-year-old man with mild idiopathic myocarditis. These arrhythmias were refractory to several anti-arrhythmic drugs. Frequent ventricular arrhythmias were reproducibly recorded in the supine position and in a 15 degree tilt from the horizontal, while they were completely abolished in positions tilted more than 30 degrees from the horizontal, at which time sinus rate increased to more than 70 beats/min. The ventricular arrhythmias were suppressed during treadmill exercise and markedly aggravated when the underlying sinus rate was decreased during sleep or lying flat in bed. The arrhythmias were entirely abolished by atropine 1 mg. Furthermore, they were suppressed during atrial pacing at the rates of 80 and 90 bpm. Ventricular tachycardia could not be induced by programmed right ventricular stimulation. The appearance of postural arrhythmias in this patient correlated with relative bradycardia suggesting that they may be related to enhanced vagal nerve activity.

Adolescent↗
PubMed1985

Cardiovascular and respiratory effects of antiarrhythmic drugs on conscious beagles.

Cardiovascular effects of antiarrhythmic drugs and their effects on the respiratory rate were examined in conscious beagles. Disopyramide, 1.5 mg/kg i.v., increased the blood pressure and decreased the heart rate, but higher dose of 5 mg/kg i.v. increased both. Disopyramide showed no central nervous side effects. Procainamide, 20 and 60 mg/kg i.v., increased the blood pressure and heart rate without changing the respiratory rate. A higher dose (60 mg/kg i.v.) of procainamide induced vomiting. Lidocaine, 2 and 6 mg/kg i.v., and phenytoin, 3 and 10 mg/kg i.v., simultaneously increased the blood pressure, heart rate and respiratory rate accompanied by excitement, and with a higher dose (6 mg/kg i.v.) of lidocaine, by convulsions. Verapamil, 0.1 and 0.3 mg/kg i.v., induced tachycardia without serious neurological effects. In conscious healthy dogs cardiovascular depressant actions of antiarrhythmic drugs could only rarely be observed.

Animals↗
PubMed1985

Mutagenicity testing of ST-film with the Ames test, chromosome test in vitro and micronucleus test in female mice.

The mutagenicity of ST-film and its components polyoxyethylenenonylether (NP-10) and polyvinylalcohol (PVAL) were studied by a reverse mutation test in S. typhimurium (Ames test), a chromosome test in cultured Chinese hamster V 79 cells and a micronucleus test in female mice. The results obtained from these test systems were all negative. Thus, it may be concluded that ST-film is not mutagenic either in vitro or in vivo mutagenicity testing systems.

Animals↗
PubMed1985

Pharmacologic studies of the central action of zopiclone: effects on locomotor activity and brain monoamines in rats.

To investigate the effects of zopiclone on the central nervous system, we examined the effects of zopiclone on brain monoamines such as dopamine (DA), noradrenaline (NA) and serotonin (5-HT) and their metabolites such as homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5-HIAA), as well as locomotor activity in comparison with those of nitrazepam and flurazepam. Zopiclone in a dose of 10 mg/kg (p.o.) significantly reduced it (p less than 0.01) in 30 min and the reduced locomotor activity persisted until 180 min. The reducing effect on locomotor activity by zopiclone was similar to that of nitrazepam and more potent than flurazepam. The effects of zopiclone on brain monoamines (MA) were examined. No significant changes in DA, NA and 5-HT were observed, but HVA and 5-HIAA were reduced. A fluorescent-histochemical study conducted simultaneously revealed almost the same results as the biochemical test results. From the facts that zopiclone inhibited locomotor activity in rats, and inhibited brain DA and 5-HT turnover, the mechanism of action of zopiclone in brain MA neurons seems to be similar to that of benzodiazepine derivatives.

Animals↗
PubMed1985

Fluorescence histochemical studies of the effects of rauwolfia alkaloid derivatives on adrenergic vasomotor nerves.

Experiments were performed to explore the influence of two rauwolfia alkaloid derivatives, rescinnamine and syrosingopine, on noradrenaline at the sympathetic nerve-endings by delineating the localization of noradrenaline in the walls of femoral artery and abdominal aorta of rats treated with these agents compared to reserpine, using the fluorescence histochemical technique. Noradrenaline-containing nerve fibers emitting an intense yellowish-green fluorescence were demonstrated circumjacent internally to the adventitial smooth muscle layer of the femoral artery in both normal rats and spontaneously hypertensive rats (SHR). In both normal rats and SHR, treatment with rescinnamine or syrosingopine in an oral dose of 5 mg/kg caused essentially the same degree of depletion of the noradrenaline fluorescence localized subjacent to the adventitial smooth musculature of the femoral artery, as did that with 5 mg/kg of reserpine. The noradrenaline fluorescence vanished completely following treatment of rats with 15 mg/kg of rescinnamine or 30 mg/kg of syrosingopine. Noradrenaline-containing nerve fibers showing yellowish-green fluorescence were observed distributed subjacent to the entire internal circumference of the adventitial smooth muscle layer of the abdominal aorta in both the normal rats and SHR. In response to oral administration of rescinnamine or syrosingopine in a dose of 5 mg/kg, both normal and SHR rats showed a diminution of the noradrenaline fluorescence in the region of adventitial smooth musculature of abdominal aorta equivalent to that evoked by 5 mg/kg of reserpine. Treatment with 15 mg/kg of rescinnamine or 30 mg/kg of syrosingopine resulted in a complete disappearance of noradrenaline fluorescence in that region.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic Fibers↗
PubMed1985

Pharmacologic studies of central actions of zopiclone: influence on brain monoamines in rats under stressful condition.

In order to investigate the central action of zopiclone, the rat brain was divided into 8 regions and the changes in monoamines (MA) in each region were examined. The effect of zopiclone on stress was also examined from changes in brain monoamines under electro-footshock stress load in comparison with that of nitrazepam and flurazepam. The animals were decapitated at 1 h after administration of zopiclone, nitrazepam and flurazepam at each dose of 1 and 10 mg/kg (p.o.). No changes in MA at each region of the brain were noted, but the metabolite, homovanillic acid (HVA) was reduced at the cortex, hippocampus, hypothalamus and cerebellum. 5-hydroxyindoleacetic acid (5-HIAA) was reduced at the amygdala. Noradrenaline (NA) turnover accelerated by electro-footshock stress load was inhibited by zopiclone. From the results of this experiment, it was found that the effects of zopiclone on brain MA were similar to those of nitrazepam and flurazepam: inhibition of 5-HT turnover at the amygdala was common to these three compounds. This result suggests that zopiclone has similar pharmacological properties to benzodiazepines as an antianxiety agent.

Amygdala↗
PubMed1985

[Effects of percutaneous transluminal coronary angioplasty on left ventricular function at rest and during exercise].

The effects of percutaneous transluminal coronary angioplasty (PTCA) on left ventricular function at rest and during stress test were examined. Effect of PTCA at rest We studied 10 patients who fulfilled the following criteria, 1) single vessel disease, 2) high grade stenosis in the left anterior descending artery, 3) successful PTCA, 4) no restenosis, 5) without electrocardiographic evidence of previous myocardial infarction, and 6) technically adequate left ventriculograms in both pre and post PTCA studies. Follow-up studies were done six months after PTCA. Filling fraction as an index of early diastolic function was significantly lower than that of normal controls. There were no significant changes in left ventricular end-diastolic pressure, peak dp/dt, negative peak dp/dt, ejection fraction, left ventricular systolic pressure/end-systolic volume, between pre- and post-PTCA studies. Filling fraction in a jeopardized area, which was supplied by the left anterior descending artery, increased significantly after PTCA. No significant change was observed in the inferior area. Effect of PTCA during stress test A contrast stress test in eight successful cases without restenosis was performed by injecting 0.7 ml per kilogram of contrast material (76% urografin) at a rate of 13 ml/sec into the left ventricle before and six months after PTCA. The left ventricular end-diastolic pressure increased to 20.1 +/- 3.8 mmHg during stress test before PTCA, and only to 14.3 +/- 5.3 mmHg after PTCA (difference highly significant). Before the procedure, negative peak dp/dt during stress test was 1782 +/- 358 mmHg/sec; it increased significantly to 2342 +/- 702 mmHg/sec after PTCA.(ABSTRACT TRUNCATED AT 250 WORDS)

Angioplasty, Balloon↗
PubMed1985

The neonatal development of benzodiazepine receptor subtypes in the rat cerebral cortex and cerebellum.

The development of benzodiazepine receptor subtypes in the rat cerebral cortex and cerebellum was studied. The proportions of Type I (CL218872 sensitive binding sites) and Type II (CL218872 insensitive binding sites) in both regions of the neonatal brain were quite different from those of adult. In one day old rat cortex and cerebellum, about 95% of the benzodiazepine receptor were Type II receptor, while these receptors comprised about 50% and 15% of the total in the adult cortex and cerebellum, respectively. From 21 days onward, these ratios in both brain regions did not significantly change through adult age (over 55 days old). The proportion of receptor subtypes in the 21 day cortex (50% type I, 50% type II) was approximately equivalent to that seen in the cerebellum at the 9th day of age. The 3H-flunitrazepam specific binding sites in both brain regions increased markedly after birth, although Type II receptor binding sites did not show any notable gain. Type II receptor specific binding sites in the cortex were not significantly different between neonatal and adult, while these sites in the cerebellum to decrease after birth. These results suggest that Type I and Type II receptors seemed to develop independently during their embryogenesis.

Age Factors↗
PubMed1985

Vector mosquitoes of Wuchereria bancrofti at Bicol region in the Philippines. 1. Transmission capability.

Mosquitoes were surveyed for the capability of filaria transmission at Sitio Bacolod and Barrio Salvacion, in Bicol region, Luzon, Philippines. The results of indoor collections and experimental infections showed that the infective rates and the median density of infective larvae per infected mosquito were significantly higher in Aedes poicilius than in Culex quinquefasciatus. Aedes poicilius was found to be the principal vector of bancroftian filariasis in this region.

Aedes↗
PubMed1985

The "status quo" of clinical pharmacology in Japan.

The status quo in the educational system of Japanese medical schools and the status quo and tomorrow in Clinical Pharmacology is described, analyzed and interpreted. All relevant criteria are considered and the stipulations are discussed which are very important for the clinical pharmacologist. The importance of clinical pharmacology in the curriculum is proved as a conditio sine qua non.

Curriculum↗