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Biomedical subjects

B N Chiang

Publications and source records attributed to B N Chiang.

At least 127 records · Page 7Linked to original sources
PubMed1987

Modulation of lymphocyte proliferation by murine liver extract.

Murine liver extract (LEx) purified by ammonium sulfate (45-70% saturation) possesses a strong inhibitory effect on human lymphocyte proliferation. We have shown that the inhibitory effect of LEx is not via a cytotoxic effect and that it is proportional to the length of incubation with LEx. Mitogen-prestimulated lymphocytes are more resistant to LEx inhibition than cells not prestimulated. B cells stimulated by PWM are more susceptible to LEx-induced inhibition than PHA- or Con A-stimulated T cells. In Con A cultures, there may be a population of cells more resistant to LEx inhibition. This population is not yet identified. The degree of reversibility of LEx inhibition was different in cells prestimulated by different mitogens. The inhibitory activity of LEx decreased in the presence of an increasing number of cells in the culture.

Animals↗
PubMed1986

Hemodynamic effect of propranolol on portal hypertension in patients with HBsAg-positive cirrhosis.

Wedged hepatic venous pressure, free hepatic venous pressure, and cardiac index were measured before and one hour after intravenous and one month after chronic oral administration of propranolol in nine patients with HBsAg-positive cirrhosis. The gradient between wedged hepatic venous pressure and free hepatic venous pressure was decreased 22.7% at one hour after intravenous administration of 5 mg propranolol, and a sustained decrease in hepatic venous pressure gradient was also demonstrated in five patients after one month of continuous oral administration of propranolol. Thus, we conclude that chronic oral administration of propranolol can reduce the hepatic venous pressure gradient in patients with compensated HBsAg-positive cirrhosis.

Adult↗
PubMed1986

The inhibitory effect of some ionophores on human sperm motility.

The inhibitory effect of five ionophores, namely, A23187, nonactin, nigericin, monensin and m-chlorocarbonyl cyanide phenylhydrazone, on human sperm motility were measured with a trans-membrane migration method. The concentrations of A23187 and nigericin that decreased sperm motility to 50% of control were 20 microM (10.5 mg/l) and 8 microM (5.8 mg/l), respectively. Because these two ionophores were more potent than previously reported membrane-active sperm-immobilizing agents, we propose that ionophores could be a new category of vaginal contraceptive if a pharmaceutical preparation that is safe to be administered in vivo can be developed.

Anti-Bacterial Agents↗
PubMed1986

Evidence for a delayed, integral, and proportional phase of glucocorticoid feedback on ACTH secretion in normal human volunteers.

To investigate the mechanisms responsible for glucocorticoid feedback on nonstress-induced ACTH secretion in normal subjects, 24 volunteer subjects (14 males and 10 females, 21 to 43 years) were divided into six groups in a randomized fashion and studied. Each subject received a single midnight dose of 30 mg/kg per body weight of metyrapone and then cortisol was administered according to different protocols in the next morning to provide extreme variations of the input signal. It was found that no obvious inhibition in plasma ACTH levels was shown during the first 15 min despite the fact that cortisol was given at rather larger doses and short time intervals. However, a significant suppression in plasma ACTH levels began to manifest approximately 30 min after cortisol administration in each study group and it became apparent that the degree of inhibition of ACTH level at 75 min correlated with the plasma cortisol concentrations at the same moment (r = 0.97, P less than 0.01) as well as with the dosage of cortisol during this time, whatever administered (r = 0.99, P less than 0.01). In summary, our data provided evidence for a delayed, proportional, and integral phase of glucocorticoid feedback on nonstress-induced ACTH secretion in normal human volunteers.

Adrenocorticotropic Hormone↗
PubMed1986

Enhancement of A23187-induced production of the slow-reacting substance on peripheral leukocytes from subjects with asthma.

Peripheral polymorphonuclear leukocytes and mononuclear leukocytes from normal subjects and subjects with asthma were studied for their production of slow-reacting substance (SRS) after nonimmunologic stimulation with the calcium ionophore A23187. The amount of SRS generated was determined in both polymorphonuclear leukocyte fractions and mononuclear leukocyte fractions from four groups of subjects: 10 with extrinsic asthma, five with mixed-type asthma, 10 with intrinsic asthma, and 10 normal control subjects. In either cell type, the SRS produced was much more in cells from subjects with extrinsic asthma and less in cells from subjects with the mixed-type asthma, intrinsic asthma, and the normal subjects in order of decreasing quantity. These results indicate the amount of SRS generated by nonimmunologic stimulation with calcium ionophore is related to the degree of atopy and suggest the existence of an intrinsic cellular defect in cells from subjects with atopic asthma in addition to the effects of higher serum levels of IgE antibodies.

Adult↗
PubMed1986

Electrophysiological effects of low pH in human atrial fibres.

In the studies of the electrophysiological properties of human atrial fibres obtained at cardiac surgery, it has often been reported that the diastolic potential, the maximum upstroke velocity of the phase 0 depolarization (Vmax) and the amplitude of action potential are relatively low. The same findings were also obtained in our previous study when the tissue preparations were perfused with a Tyrode solution which, as usually described in literatures on cardiac cell studies had a NaHCO3 concentration of 12 mM and was aerated with a gas mixture of 95% O2-5% CO2 at 37 degrees C. Recently we found that the relatively poor electrical activities of the human atrial fibres were related to the low pH value (around 7.06) of the perfusate used. Raising the pH value of the perfusate either by increasing the NaHCO3 concentration or by reducing the CO2 in the bubbling gas mixture significantly improved the electrical activities of the fibres. There is evidence that the suppressive effect of low pH on the electrical activities is due to the hindering action of H+ on the transportation of other cations across the plasma membrane.

Cardiac Surgical Procedures↗
PubMed1986

Effect of phosphatidylcholine, lysophosphatidylcholine, arachidonic acid and docosahexaenoic acid on the motility of human sperm.

Lysophosphatidylcholine, arachidonic acid and docosahexaenoic acid were found to have a concentration-dependent inhibitory effect on the motility of human sperm, whilst phosphatidylcholine had no effect. Seminal plasma attenuated the sperm-immobilizing potencies of these lipids. Because all of the three inhibitors of motility are hydrolytic products of phosphatidylcholine, and the catalytic enzyme, phospholipase A2, is known to be calcium dependent, it is suggested that calcium might inhibit sperm motility by activating phospholipase A2 which in turn releases lysophosphatidylcholine and free fatty acids.

Arachidonic Acids↗
PubMed1986

Arterial hemodynamics in human hypertension.

Differences in aortic impedance between normotensives and hypertensives are not well characterized. We examined impedance in 8 normotensive and 11 hypertensive (mean 96.7 vs. 122.2 mmHg) age-matched, Chinese patients undergoing cardiac catheterization at rest, during nitroprusside, and handgrip exercise before and after beta blockade (propranolol). Hypertensives had higher resistance (2,295 vs. 1713 dyn-s/cm5), characteristic impedance (145.7 vs. 93.9 dyn-s/cm5), total external power (1,579 vs. 1174 mW), peripheral reflections (ratio of backward to forward wave components of 0.54 vs. 0.44), and first zero crossing of impedance phase angle (4.15 vs. 2.97 Hz). These abnormalities were eliminated with vasodilatation. Differences between groups were not further exacerbated when pressure was increased during handgrip exercise. Beta blockade further increased resistance and reflections. Thus, hemodynamic abnormalities of essential hypertension (increased resistance, reflections, and pulse wave velocity, and decreased compliance) are compatible with an increased vasomotor tone that is further unmasked during generalized beta blockade.

Adult↗