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Biomedical subjects

D Chu

Publications and source records attributed to D Chu.

At least 73 records · Page 4Linked to original sources
PubMed1979

Dimeditiapramine (Ro 11-1781), a new calcium antagonist, in the management of supraventricular tachyarrhythmias in patients with acute myocardial infarction.

18 patients with acute myocardial infarction and sustained arrhythmias were treated with a new Ca2+ antagonist, Ro 11-1781, at the dose of 1.0 mg/kg i.v. The drug was effective in reducing heart rate to less than 90 beats/min in 9/10 patients with atrial fibrillation, in 3/4 patients with atrial flutter and in 3/4 patients with supraventricular tachycardia. The peak effect was observed within 2--5 min after the intravenous administration of Ro 11-1781. In cases with recurring tachyarrhythmias, the drug was also effective in repetitive administration. Systolic blood pressure was reduced, but severe hypotension (less than 90 mm Hg) was not observed. The atrioventricular conduction in these patients remained unimpaired and asystole did not occur. The drug appears to be an effective and a well tolerated antiarrhythmic agent.

Aged↗
PubMed1979

Human electropharmacology of the calcium antagonist dimeditiapramine (Ro 11-1781) in coronary patients.

The electrophysiological effect of dimeditiapramine (Ro 11-1781), a Ca2+ antagonist, was evaluated in 20 patients with coronary heart disease. Electrophysiological measurements, including sinus cycle length, sinoatrial conduction time, intra-atrial conduction time, atrial, atrioventricular, nodal and ventricular refractory periods and intraventricular conduction time were recorded before and after the intravenous administration of Ro 11-1781. At a dose which is effective against cardiac arrhythmias, Ro 11-1781 produced no statistical significant changes in the sinoatrial and intraventricular conduction time. Similarly, neither the sinoatrial nor the ventricular refractory period was affected. Ro 11-1781, however, increased the atrioventricular conduction time and decreased the systolic blood pressure to a statistically significant extent. The tolerance was very good.

Adult↗
PubMed1979

Therapeutic effects of pindolol and nifedipine in patients with stable angina pectoris and asymptomatic resting ischemia.

A single blind randomized parallel study designed to assess the anti-anginal efficacy of pindolol and nifedipine was carried out in 42 ambulatory coronary patients with stable angina pectoris. Drug efficacy was assessed in terms of (a) pain, (b) frequency of anginal episodes, (c) nitroglycerin consumption, (d) exercise tolerance and (e) ST-segment changes. The effect of these drugs on asymptomatic resting myocardial ischemia was also assessed by means of 24-h dynamic electrocardiography (DCG). All patients were checked at weekly intervals. At the end of a 4-wk placebo period, the patients were randomly assigned either to the pindolol or nifedipine group. The treatment lasted for 45 days. During the placebo period, ischemic ECG changes and symptoms of coronary insufficiency were detected in all patients. Furthermore, 12 out of 42 patients had asymptomatic myocardial ischemia at rest. One patient from each group was dropped because of tolerance. At the end of the 45-day study, pindolol and nifedipine were equi-effective on spontaneous and effort-related angina. There were, however, some differences: increased tolerance to exercise appeared earlier with pindolol: the pindolol group showed a slightly reduced while the nifedipine group showed a slightly increased heart rate. Furthermore, nifedipine reduced or eliminated asymptomatic myocardial ischemia in 6 out of 7 patients while only 1 out of 5 improved in the pindolol group.

Adult↗
PubMed1979

The therapeutic value of clonidine in patients with coronary heart disease.

11 coronary patients, 8 with mild hypertension, were treated with clonidine, at a dose of 75 micrograms b.i.d. per os for a week. The effect of the drug on coronary heart disease was assessed by means of a symptom-limited multistage exercise test on the cycloergometer. Clonidine was effective in reducing the exercise-induced increases in blood pressure (by 15.5 +/- 6.1%), the double product (by 34.8 +/- 20.8%) and the electrocardiographic ischemic changes. In 2/4 patients, effort related ventricular extrasystoles were reduced by greater than 50% after clonidine. The drug worsened the anginal pain in 3 and relieved the pain in 3 patients. However, it reduced the exercise-induced ST-T segment downsloping in 7 patients. The tolerance was good, since only 3/11 patients reported slight dry mouth, sedation and pyrosis. In view of the electrocardiographic effect, further studies with clonidine on myocardial ischemia should be performed.

Angina Pectoris↗
PubMed1978

Intrinsic sympathomimetic activity of beta-adrenoceptor blocking agents.

The pharmacological methods used to assess the intrinsic sympathomimetic activity (ISA) of beta-blockers are discussed. The clinical relevance of ISA to respiratory function, peripheral resistance and cardiac function is reviewed. It appears doubtful whether ISA is always of predominant clinical significance and an alternative explanation is offered for many clinical effects observed with certain beta-blockers, e.g. pindolol, oxprenolol, tolamolol, metoprolol, etc. Some effects of these beta-blockers resemble those of labetalol, a new drug with both alpha and beta-blocking activity. Some clinical effects of certain beta-blockers are more likely to be due to alpha-blocking activity than to their ISA.

Adrenergic alpha-Antagonists↗
PubMed1978

An evaluation of cadmium telluride detectors for computer assisted tomography.

Cadmium telluride (CdTe) presents a set of extremely attractive features as an X-ray detector for computer assisted tomography (CAT). It is stable and easily handled; has a high detection efficiency and very efficient conversion of energy to charge; and permits a high element density in a compact configuration. Unfortunately, effects due to "polarization," "tailing," high and variable leakage currents, and long "memory" are incompatible with the needs of CAT instrumentation. Pulse-processing techniques have allowed us to eliminate these problems in positive-sensitive detectors, thus opening the way for utilization of CdTe in CAT.

Cadmium↗
PubMed1978

Anaesthetised normotensive rats for the detection of hypotensive activity of a beta-adrenoceptor antagonist and other antihypertensive agents.

A simple method for the detection of antihypertensive activity in anaesthetised (66 mg/kg i. v. alpha-chloralose and 20 mg/kg i. v. aprobarbital) normotensive rats is described. Dihydralazine (0.5 to 2 mg/kg i. v.) reduced blood pressure dose-dependently but did not provoke the anticipated tachycardia. Clonidine (1 to 8 microgram/kg i.a.), guanethidine (0.5 to 5 mg/kg i.a.) and alpha-methyldopa (2.5 to 10 mg/kg i.a.) reduced blood pressure dose-dependently; the effect of reserpine (0.1 to 1.0 mg/kg i.a) was, however, not dose-dependent. Although all four drugs reduced heart rate, only clonidine and guanethidine did so in a dose-dependent manner. Phentolamine (0.5 to 2 mg/kg i. v.) and propranolol (0.01 to 1 mg/kg i. v.) elicited dose-dependent falls in blood pressure. Whereas phentolamine increased heart-rate slightly, propranolol elicited a bradycardia. It is concluded that the chloralose-aprobarbital anaesthetised rat is a suitable and economical model for the screening of potential antihypertensive agents including beta-adrenoceptor antagonists. However, reflex trachycardia provoked by peripheral vasodilators may not be apparent.

Adrenergic beta-Antagonists↗
PubMed1977

Anti-inflammatory activity in oak gall extracts.

A method for the purification of the Hungarian oak gall extracts containing anti-inflammatory activity is described. The anti-inflammatory activity of the purified extract was tested in the carrageenan-induced rat paw edema and in rat polyarthritis induced by mycobacterial adjuvant. In doses of 4.3 and 8.5 mg/kg i.p., the extract inhibited dose-dependently the formation of paw edema induced by carrageenan in rats. When rats were treated daily from 3 days prior to and 16 days after the injection of the mycobacterial adjuvant, the severity of the polyarthritic symptoms was significantly reduced.

Animals↗
PubMed1975

Biologically active substances in oak gall extracts. Part 1: Isolation and chemical identification of a substance exerting antihistamine-like activity (KC-18).

The previously reported antihistamine-like activity of partially purified oak gall extracts has been confirmed. Isolation of the active principle was achieved through the use of organic solvent extractions and column chromatographic (Sephadex LH-20 and silica gel) procedures. Preliminary investigation on the structure of this chemically pure substance using mass spectrometry, thin layer chromatography, base hydrolysis and electrophoresis indicated that it is most probably an ester of piperonylic acid. KC-18, given intraperitoneally in doses of 4 mg/kg to guinea pigs 5 hours prior to an exposure to a 0.15 per cent histamine aerosol, significantly reduced the bronchoconstrictor effect of histamine.

Animals↗
PubMed1975

Biologically active substances in oak gall extracts. Part 11. The antihistamine-like activity of a substance (KC-18) isolated from oak gall extracts.

The effects of the newly isolated antihistamine (KC-18) from the Hungarian oak gall extracts on some actions of histamine have been investigated. Intraperitoneally administered KC-18 into guinea pigs and cats in doses of 2.5-16 mg/kg exerted a significant dose-related inhibition of histamine-induced bronchoconstriction, increase in capillary permeability and hypotension. In guinea pigs, actively sensitized with ovalbumin, 4 mg/kg KC-18 administered intraperitoneally prevented the development of anaphylactic shock following antigenic challenge. Histamine-induced gastric acid secretion in the rat was also dose-relatedly reduced by the intravenous administraton of 72 and 120 mg/kg KC-18. However, KC-18 in doses up to 100 mug/ml did not modify the histamine-induced contraction of the isolated guinea pig ileum.

Aerosols↗