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Biomedical subjects

C G Wang

Publications and source records attributed to C G Wang.

At least 55 records · Page 3Linked to original sources
PubMed1986

Methacholine-induced airway reactivity of inbred rats.

Dose-response curves to inhaled aerosolized methacholine chloride (MCh) were obtained in anesthetized spontaneously breathing rats. Thirty rats (10/strain), randomly selected from highly inbred ACI, Lewis (L), and Brown Norway (BN) strains and 40 rats (20/strain) from similarly inbred Wistar-Furth (WF) and Buffalo (Buf) strains were studied. Airway responses were quantitated from changes in pulmonary resistance (RL) and airway reactivity was calculated as the dose of MCh required to increase RL to 150% (ED150RL) and 200% (ED200RL) of base line. There were no statistically significant differences in ED150RL and ED200RL among the five rat strains. Large interindividual variability was present as evidenced by 128-fold differences in ED150RL and ED200RL between the least and most sensitive animal of the same strain. In contrast, seven animals studied repeatedly on different days had values of ED150RL that differed by an average of only 2.9-fold (range 1.6-5.3). Thirteen rats that were studied on two occasions separated by an interval of 3 mo showed no systematic changes in airway reactivity. We conclude that airway reactivity to inhaled methacholine in anesthetized nose-breathing rats is not strain related, and despite animals of a given strain being genetically identical, the variability in airway reactivity within strains suggests that environmental rather than genetic factors are the major determinants of that reactivity.

Airway Resistance↗
PubMed1985

Central and local cholinergic components of histamine-induced bronchoconstriction in dogs.

To determine the importance of central and local reflexes in the bronchoconstriction produced by inhaled aerosolized histamine, chloralose-urethan-anesthetized dogs were intubated with a double-lumen catheter, ventilated with a dual cylinder respirator, and instrumented for the measurements of pulmonary conductance (GL) and dynamic compliance (Cdyn) in each lung. In each dog, dose-response curves to inhaled aerosolized histamine were obtained in both lungs separately but synchronously. Four series of experiments were performed. In the first series (n = 10) the responses of the right and left lungs were compared and found to be approximately equal, indicating that one lung could be used as a control for the other. In the second and third series the dose-response curve of one lung that had either been treated with inhaled atropine sulfate (n = 6) (4 mg/ml) or vagotomized (n = 4) was compared with the contralateral control lung. At low concentrations of histamine, GL and Cdyn decreased more in the control lungs than in their atropine-treated or vagotomized counterparts, and approximately 40% of the bronchoconstriction induced was reflex in origin. At higher concentrations of histamine the responses of the control and atropine-treated or vagotomized lungs were not significantly different. In the fourth series of experiments (n = 6) histamine dose-response curves were obtained following combined bilateral vagotomy and unilateral delivery of inhaled aerosolized atropine. In these dogs GL, but not Cdyn, fell to a greater extent in the control than in the atropine-treated lung.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1985

Segmental pulmonary vascular resistance in progressive hydrostatic and permeability edema.

We used the in situ blood-perfused left lower lobe preparation of the dog to examine the effect of hydrostatic and permeability edema on the slope and intercept of the vascular pressure-flow (P/Q) relationship and on the longitudinal distribution of vascular resistance with the arterial and venous occlusion technique. Hydrostatic edema (HE) was induced by raising the venous pressure, and permeability edema (PE) was induced with alpha-naphthylthiourea. When the hematocrit (Hct) of the perfusate was kept normal (approximately 40%), HE had no significant effect on either the slope or the intercept of the P/Q relationship or on the distribution of vascular resistance. PE caused a small increase in the intercept of the P/Q relationship and a small rise in the resistance of the vessels in the middle segment. In another series of HE experiments in which Hct was allowed to increase during edema formation, there was a marked increase in vascular resistance. We conclude that edema per se does not increase vascular resistance significantly and that the increases in vascular resistance which were observed previously by other investigators in the isolated lungs may be due to increases in blood hematocrit.

Animals↗
PubMed1985

Effect of chronic cigarette smoke exposure on pulmonary vasomotion in beagle dogs.

To study the effect of chronic cigarette smoke exposure on the resistive properties of the pulmonary vasculature, left lower lobes from 12 control beagles and 6 beagles who had smoked cigarettes (50 cigarettes/wk for 40 wk) were perfused in situ to measure the vascular pressure-flow relationship and the resistance of the three vascular segments with the arterial and venous occlusion technique. In control subjects the vascular resistance in the arterial, middle, and venous segments was 23, 36, and 41% of the total, respectively. The segmental distribution of vascular resistance was not significantly different in the cigarette smoke-exposed dogs, despite the fact that the absolute values were 30-40% less than that of the control group. The longitudinal distribution of resistance among the three vascular segments and their response to drugs were different in beagles than was previously found in mongrels. In all beagles the veins were considerably more reactive than arteries. Vasoconstriction with serotonin (5-HT) prostaglandin F2 alpha (PGF2 alpha), norepinephrine, histamine, and methacholine (M) infusion occurred predominantly in the veins. The effect of PGF2 alpha and 5-HT was totally different than that previously observed in mongrels in which the constriction was predominantly in the arteries. Chronic cigarette smoking reduced the basal pulmonary vascular resistance and attenuated the venoconstrictor response to 5-HT and M but potentiated the hypoxic pressor response of the microvessels.

Animals↗
PubMed1984

Waterborne outbreak of rotavirus diarrhoea in adults in China caused by a novel rotavirus.

During two epidemics of acute diarrhoea in China in late 1982/early 1983, more than 12 000 adults in two coal mining districts were affected. The virus isolated from stool samples resembled a rotavirus morphologically. Antigenically it lacked the group antigen shared by known rotaviruses. Like other rotaviruses it had a double-stranded RNA with 11 discrete segments, but the pattern of migration of the segments on polyacrylamide electrophoresis differed from those of other rotaviruses.

Adolescent↗
PubMed1980

Gaseous isotope separation using solar wind phenomena.

A large evacuated drum-like chamber fitted with supersonic nozzles in the center, with the chamber and the nozzles corotating, can separate gaseous fluids according to their molecular weights. The principle of separation is essentially the same as that of the solar wind propagation, in which components of the plasma fluid are separated due to their difference in the time-of-flight. The process can inherently be very efficient, serving as a pump as well as a separator, and producing well over 10(5) separative work units (kg/year) for the hydrogen/deuterium mixture at high-velocity flows.

Journal Article↗