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Biomedical subjects

S Imai

Publications and source records attributed to S Imai.

At least 721 records · Page 40Linked to original sources
PubMed1982

Canine-effective plasma concentrations of antiarrhythmic drugs on the two-stage coronary ligation arrhythmia.

Seven drugs were tested for their antiarrhythmic effects on ventricular arrhythmias 24 and 48 hr after two-stage coronary ligation in conscious beagles. Venous blood samples were drawn for plasma drug assays. Minimum effective plasma concentrations of drugs were calculated from derived concentration-time curves. Effective drugs and their minimum effective concentrations for the suppression of arrhythmias 24 and 48 hr after coronary ligation were: disopyramide, 4.2 and 2.3 micrograms/ml; procainamide, 26.4 and 27.0 micrograms/ml; phenytoin, 8.4 and 6.4 micrograms/ml; and a new beta-blocker, N-696, 7.6 and 8.7 micrograms/ml. The concentrations of disopyramide and phenytoin were almost the same as those reported for human antiarrhythmic concentrations, but those of procainamide were higher than those reported for man. Lidocaine, verapamil and a new beta-blocker, OPC-1427, were ineffective. Membrane-stabilizing effects seem to be important in suppressing the canine two-stage coronary ligation arrhythmia.

Animals↗
PubMed1982

[Trichogenic trichoblastoma].

A case of rare follicular tumor, which occurred on nasal root of a 73-year-old man, is presented. Histologically one finds a tumor, localized in dermis and subcutaneous tissue, consisting of keratinous cysts, irregular shaped or antlerlike epithelial cell nests and surrounding stroma. The cell nest consists of basaloid cells. Moreover rudimentary hair matrix structures, sebaceous gland lobules and apocrine sweat ducts are observed. This tumor corresponds to trichogenic trichoblastoma as proposed by Headington.

Humans↗
PubMed1981

Giant cell carcinoma of the pancreas.

A case of giant cell carcinoma of the pancreas is reported herein. The patient is a 67-year-old Japanese woman complaining of ascites, general fatigue, loss of weight, abdominal distention, nausea, and vomiting. Cytological diagnosis of ascites revealed adenocarcinoma. At autopsy, a whitish tumor measuring around 5 cm in diameter was found at the head of the pancreas. Metastasis was seen only in the liver. Histological examination displayed bizarre multinucleated giant cells occasionally phagocytosing the tumor cells and neutrophils.

Aged↗
PubMed1981

A comparison of the differential effects of nitroglycerin, nifedipine and papaverine on contractures induced in vascular and intestinal smooth muscle by potassium and lanthanum.

To elucidate the mechanisms of smooth muscle relaxant effects of nitroglycerin, the effects of this substance on the potassium contracture (K+-contracture) and the lanthanum-induced contracture (La3+-contracture) were studied using smooth muscle preparations of the canine coronary artery and colon and the findings compared with the effects of nifedipine, a representative calcium antagonistic vasodilator. The effects of papaverine, a prototype smooth muscle relaxant, were also studied. La3+-contracture was induced in a calcium-free environment with the addition of lanthanum, an effective blocker of calcium influx. In the coronary artery, nitroglycerin produced a relaxation both of the La3+-contracture not K-contracture in the colon was affected. Nifedipine did not relax the La3+-contracture in a range of doses at which K+-contracture of both types of smooth muscles was relaxed. Papaverine produced a relaxation of La3+-contracture as well as K+-contracture, in both types of smooth muscles. Unlike the mechanism related to the relaxant effects of nifedipine, which is generally admitted to be an inhibition of calcium influx, the relaxant effect of nitroglycerin was attribute to the suppression of calcium release from the intracellular store sites and/or stimulation of calcium uptake into the intracellular store-sites. Papaverine was assumed to produce a relaxation through augmentation of the calcium binding to the intercellular store sites for calcium as well as through inhibition of the calcium influx.

Animals↗
PubMed1981

Effect of lidocaine and procaine on the action potential of canine sinus nodal cells.

Effects of local anesthetics (lidocaine and procaine) on the canine sinus node were studied using isolated right atrial preparations which were obtained from puppies adn perfused with oxygenated Tyrode solution through the dorsal right atrial artery. Action potential of the sinus nodal area which was characterized by the slow rate of phase O and diastolic depolarization, was recorded using the conventional microelectrode technique, simultaneously with atrial contraction. Lidocaine (10-300 micrograms) prolonged the cycle length and duration of action potential, decreased the rate of phase 4 depolarization and amplitude of action potential, and shifted the threshold potential and maximal diastolic potential to the depolarizing direction. The atrial contraction decreased simultaneously. In higher doses, sinoatrial block was occasionally observed in 8 of 55 experiments. Procaine (10-300 micrograms) had similar negative chronotropic and inotropic effects and induced sinoatrial block in 7 of 57 experiments, but unlike lidocaine, procaine produced positive chronotropic and inotropic effects following the initial negative responses in 16 of 57 experiments. The sinus node acceleration was accompanied by an increase in the rate of phase 4 depolarization. Chronotropic changes of the sinus nodal cells by these drugs were accompanied by the changes in both the rate of phase 4 depolarization and duration of the action potential.

Action Potentials↗