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Biomedical subjects

B N Chiang

Publications and source records attributed to B N Chiang.

191 records · Page 11Linked to original sources
PubMedDate not supplied

Thrombus formation in the ascending aorta: a complication of angioplasty.

Percutaneous transluminal coronary angioplasty (PTCA) is recognized as an effective therapeutic procedure for nonsurgical relief of critical coronary stenosis. However, this procedure has the inherent traumatic risk of thromboembolic phenomenon in treated patients. This paper describes a hiterto unreported complication. In two patients a thrombus appeared in the ascending aorta during PTCA performed in the left anterior descending artery (LAD). Mechanisms involved are postulated. It is emphasized that particular attention should be paid to the lateral view in dilatation to treat LAD lesion, especially if the procedure is prolonged.

Angioplasty, Balloon↗
PubMedDate not supplied

Controlled trial of vasopressin plus nitroglycerin vs. vasopressin alone in the treatment of bleeding esophageal varices.

Thirty-nine patients admitted during a 16-month period for acute bleeding from varices confirmed by emergency endoscopy were randomized to receive either continuous intravenous infusions of vasopressin alone (0.66 units per min) (Group I: 19 patients) or vasopressin plus sublingual nitroglycerin (0.6 mg every 30 min for 6 hr) (Group II: 20 patients). The two groups of patients were similar in the type and severity of their cirrhosis. Bleeding was controlled initially in 47% (9/19) of the patients in Group I and 55% (11/20) of the patients in Group II after 6 hr of infusion (not statistically significant). Complete control of bleeding during 24 hr of infusion was achieved in only 4 of 19 patients in Group I (21%) but in 9 of 20 in Group II (45%). This difference is not statistically significant. The total number of patients with complications during infusions were significantly different statistically in the vasopressin and vasopressin-nitroglycerin groups, respectively (17/19 vs. 7/20, p less than 0.001). Major complications requiring immediate cessation of infusions were observed in 6 of 19 of the patients in Group I (32%) and in 2 of 20 in Group II (10%) (p less than 0.05). Mortality (58% in Group I, 55% in Group II) and transfusion requirements were similar in the two groups. This study shows that the addition of sublingual nitroglycerin to intravenous vasopressin does not alter the efficacy of vasopressin alone in controlling hemorrhage from esophageal varices, but it does significantly reduce the complications.

Administration, Oral↗
PubMedDate not supplied

The hemodynamic effect of verapamil on portal hypertension in patients with postnecrotic cirrhosis.

Wedged hepatic venous pressure, free hepatic venous pressure and cardiac index were measured before and 1 hr after i.v. administration as well as 1 month and 3 months after chronic oral administration of verapamil in 10 patients with HBsAg-positive cirrhosis. The gradient between wedged hepatic venous pressure and free hepatic venous pressure was decreased 14% at 1 hr after i.v. administration of 10 mg verapamil, and the sustained decrease in hepatic venous pressure gradient was also demonstrated in the patients after 1 month, and in six patients after 3 months of continuous oral administration of verapamil. The mean arterial pressure significantly decreased (p less than 0.01) 1 hr after the administration of verapamil. There was no significant change in other hemodynamic values. We conclude that chronic oral administration of verapamil can reduce the hepatic venous pressure gradient in patients with compensated HBsAg-positive cirrhosis and portal hypertension.

Adult↗
PubMedDate not supplied

The mechanisms of the inhibitory effects of liver extract on lymphocyte proliferation. III. The effects of arginase on DNA polymerase activities.

The incorporation of labeled precursors into DNA, RNA and protein in phytohaemagglutinin (PHA)-prestimulated human lymphocytes was maximally inhibited by liver extract (LEx) or arginase at 24 h. The activities of DNA polymerase alpha, beta and gamma were less inhibitable by these agents than was [3H]thymidine incorporation. The inhibition of DNA, RNA and protein syntheses by either LEx or arginase is probably due to arginine depletion by arginase activity, since their syntheses were similarly inhibited when cultured in an arginine-free medium in the absence of arginase. These results indicate that arginase nonspecifically inhibits the activities of DNA polymerase. The inhibition is probably due to arginine depletion.

Animals↗
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Pulmonary venous flow: its relationship to left atrial and mitral valve motion.

The factors affecting pulmonary venous flow were studied in a group of 50 patients divided into four groups. Group 1 consisted of 14 normal subjects. Group 2 consisted of 10 patients with pure mitral stenosis and normal sinus rhythm. Group 3 consisted of 15 patients with pure mitral stenosis and atrial fibrillation. Group 4 consisted of 11 patients with atrial fibrillation alone. Pulmonary venous flow, atrial septal motion, and mitral valve flow were obtained by transesophageal echocardiography. Pulmonary wedge pressure or left atrial pressure was measured invasively in all patients. We observed that pulmonary venous flow had a reversed flow during atrial contraction and a biphasic flow in the ventricular phase. The first phase of flow occurred during ventricular systole, corresponding to the beginning of atrial relaxation. The second phase of flow, during ventricular diastole, occurred consistently after the rapid filling wave of mitral flow. The beginning of the second phase, corresponding to maximal relaxation of the atrial septum, reached a maximum corresponding to the beginning of atrial contraction. Results of the present study also indicate that decrease or absence of reversed atrial flow and decrease in the first phase of ventricular flow were noticeable in patients in Groups 2, 3, and 4. The second phase of pulmonary venous flow was significantly decreased in patients with mitral obstruction (Groups 2 and 3), but was maintained when the mitral valve was normal (Group 4). In six patients undergoing percutaneous mitral valvuloplasty, the ventricular phase of pulmonary venous flow increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Fibrillation↗
PubMedDate not supplied

Two plasminogen activators, streptokinase and urokinase, stimulate human sperm motility.

The stimulatory effects of two plasminogen activators, namely streptokinase and urokinase, were measured with a trans-membrane migration method. Both drugs induced maximal motility increase at a concentration of 200 international unit/ml; the amplitude of maximal motility increase ranged from 17% to 19% of control. Although their stimulatory effects were much less than those of calcium regulating agents, the clinical application of these two drugs for improving the successful rate of artificial insemination deserves further investigation because the action site is seminal plasma rather than sperm.

Dose-Response Relationship, Drug↗
PubMedDate not supplied

A motile human sperm head fixation method.

In a solution containing less than 5% seminal fluid, human sperm has a tendency to attach its head on the smooth surface of an object. Based on such a phenomenon, a simple method was developed to fix sperm head on the surface of glass slide. This method was demonstrated by studying caffeine effect on the tail movement of human sperm in phosphate buffered saline. By analysing the images recorded on a videocassette, caffeine, a well known stimulator of human sperm motility, was shown to induce an immediate increase of sperm TBF (tail beat frequency) and the amplitude of TBF increase was found to be larger in sperm with lower basal TBF value. This method can provide a flock of head-fixed motile sperm for a precise sperm tail movement assessment or for other purposes.

Caffeine↗
PubMedDate not supplied

Electropharmacologic characteristics and radiofrequency catheter ablation of sustained ventricular tachycardia in patients without structural heart disease.

Twenty-six patients (mean age 39 +/- 17 years) with idiopathic sustained ventricular tachycardia (VT) were included for study. The patients were divided into two groups: group I: 14 patients with VT originating from the right ventricular outflow tract (wide QRS tachycardia with complete left bundle branch block pattern), and group II: 12 patients with VT originating from the left ventricle (wide QRS tachycardia with complete right bundle branch block pattern). Most of the group I patients (11/14) needed isoproterenol to facilitate induction of VT, and were sensitive to both verapamil and adenosine. Eight patients had successful radio-frequency (RF) ablation and were free of VT without any antiarrhythmic drugs. In group II, sustained VT was induced by programmed ventricular stimulation in all the patients (only 3 patients needed isoproterenol for facilitation); verapamil could terminate all the VT but none of the patients responded to adenosine. Eight patients received RF ablation and 6 patients had successful ablation without recurrent tachycardia on a long-term basis. Different sensitivity to adenosine and isoproterenol between right and left ventricular idiopathic VT suggested different underlying mechanisms for both types of VT. The patients who did not receive catheter ablation still had attacks of VT despite antiarrhythmic drug treatment; however, none of these patients had sudden death since the first attack of VT (mean 95 +/- 51 months), suggesting a benign prognosis in idiopathic VT.

Adolescent↗