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Biomedical subjects

J Wei

Publications and source records attributed to J Wei.

At least 271 records · Page 15Linked to original sources
PubMed1989

Electromechanical effects of protamine in isolated human atrial and canine ventricular tissues.

Effects of protamine sulfate (1-100 mg%) on the electrical and mechanical activities of isolated dog ventricular tissues and human atrial fibers were studied. In dog Purkinje fibers, 10 mg% protamine reduced markedly the maximum diastolic potential and the rate of phase 0 depolarization. Eventually, slow response action potential developed at a depolarized level and the twitch force declined abruptly. The depolarization and the negative inotropy were reversed by increasing [Ca])o or [K]o but not by tetrodotoxin. When Purkinje fibers were depolarized in 27 mM [K]o Tyrode solution plus 0.5 microM epinephrine, higher concentrations of protamine (30 mg% or above) were required to depress the slow response action potentials and twitch, in contrast to the action of verapamil and diltiazem (1-30 microM). Dog ventricular and human atrial muscle fibers were more resistant to the depressant effects of protamine. In human atrial fibers, however, 10 mg% protamine was able to depress significantly the oscillatory afterpotentials and aftercontractions induced by epinephrine and theophylline. The present findings suggest that the depolarization and decline in force of cardiac tissues induced by protamine, at a concentration about twice of the maximum clinically relevant dose, may be explained by the development of slow response action potentials as a result of decrease in membrane K+ and Na+ conductances.

Action Potentials↗
PubMed1988

Depressant effects of isoflurane and halothane on isolated human atrial fibers.

The present experiments were designed to study the cellular mechanism responsible for the depressant effects of halothane and isoflurane on human atrial tissues obtained at cardiac surgery. The fibers were superfused in Tyrode's solution, and transmembrane potentials were recorded with a microelectrode technique. In atrial fibers showing fast response action potential (maximum velocity of depolarization [Vmax] greater than 100 V/s), halothane (0.75 vol%, 0.44 mM) and isoflurane (1.25 vol%, 0.53 mM) decreased slightly the upstroke velocity but depressed the plateau and twitch force significantly. In atrial fibers showing slow rate of phase-0 depolarization or when atrial fibers were depolarized in high [K]0, both halothane and isoflurane decreased the upstroke of slow response and the force. The depressant effects of anesthetics partially mimicked the actions of 1 microM tetrodotoxin and diltiazem and could be reversed by epinephrine or high [Ca]0. The delayed afterdepolarizations or aftercontractions and contracture induced by epinephrine or strophanthidin were also inhibited by both anesthetics. Halothane and isoflurane may depress normal electromechanical activity and arrhythmogenic triggered activity through a reduction of cation fluxes across the cell membrane.

Action Potentials↗
PubMed1987

Controlled reperfusion following regional ischemia.

The ability to reverse acute coronary occlusion with fibrinolytic agents and percutaneous transluminal angioplasty has increased interest in the revascularization of ischemic myocardium. This study defines changes in global ventricular function, mass, and compliance during acute coronary occlusion and following reperfusion with blood in the beating and arrested heart. In 17 dogs on cardiopulmonary bypass, the proximal left anterior descending coronary artery was occluded for 45 minutes. In 12 dogs, flow was reestablished by releasing the coronary snare in the beating heart. In the other 5 dogs, the snare was released during a continuous 10-minute infusion of blood potassium cardioplegia in the arrested heart. Coronary occlusion resulted in significant decreases in stroke work index and left ventricular (LV) mass, but compliance was unchanged. Reperfusion in the beating heart increased LV mass compared with the values measured before ischemia (104 +/- 5 versus 95 +/- 5 gm; p less than 0.05) and decreased LV compliance (39 +/- 4 versus 53 +/- 4 ml at LV end-diastolic pressure of 8 mm Hg; p less than 0.05). In contrast, with blood cardioplegia-based reperfusion in the arrested heart, LV mass and LV compliance remained unchanged from control values. We conclude that revascularization of acutely ischemic myocardium in the beating heart further impairs LV function by increasing LV mass and decreasing compliance. This damage can be avoided by reperfusion with blood cardioplegia in the arrested heart.

Animals↗
PubMed1986

A comparison of results of type I and type II radical operations for carcinoma of the gastric cardia.

During 1954-1981, 527 patients with cancer of the gastric cardia underwent resection. Of these, 146 underwent type I radical operation (transthoracic resection) with eight (5.5%) operative deaths; 344 underwent type II radical operation (abdominothoracic resection) with 42(12.2%) operative deaths; and 37 with Stage IV lesions underwent extended operation or palliative operation with 4(10.8%) operative deaths. Of 440 cases of Stage I-III cases that survived the operation, the 5-year survival rate was 18.5%, and the 10-year survival rate was 10.7%. For stage I cancer, the end results of type I and type II radical operations were similar. In Stage II, whether the lymph nodes were positive or negative, the end result of the type II operation was better, but without statistical significance. In Stage III cancer without lymph node metastases, the end result of the type II operation was better, but without statistical significance; in those with lymph node metastases, the type II operation was definitely better than the type I operation (P less than 0.05).

Adenocarcinoma↗
PubMed1986

A giant congenital aneurysm of the right coronary artery.

A young woman with shortness of breath was diagnosed preoperatively as having a coronary artery aneurysm. The aneurysm originated from the right coronary artery and was extraordinarily large. The aneurysm was excised successfully under extracorporeal circulation.

Adult↗