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Biomedical subjects

J A Pang

Publications and source records attributed to J A Pang.

29 records · Page 2Linked to original sources
PubMed1985

Acute pericarditis. An unusual presentation of an exacerbation of ulcerative colitis.

Acute pericarditis is an unusual complication of ulcerative colitis. In some rare cases, it is the only extraintestinal manifestation of the underlying colitis, and may even precede the development of bowel symptoms. Less rarely, pericarditis may be the presenting feature of an exacerbation of ulcerative colitis. Such a case is reported to illustrate the important, but uncommon, association of these disorders, and to discuss the implications for management.

Adrenal Cortex Hormones↗
PubMed1984

Carcinoma of the colon, sclerosing cholangitis, pericholangitis, and bronchiectasis in a patient with chronic ulcerative colitis.

We report a patient with long-standing ulcerative colitis who developed carcinoma of the colon, sclerosing cholangitis, pericholangitis, and bronchiectasis over the course of 10-15 years. Occurrence of these rare conditions in the same patient supports their reported association and reemphasizes that there may be multisystem involvement in ulcerative colitis.

Bronchiectasis↗
PubMed1983

Effect of beta-adrenergic blockade on hyperventilation and exercise tolerance in emphysema.

Ventilation, heart rate, and arterial blood gas tensions were measured at rest and during incremental exercise in 10 patients with emphysema after intravenous placebo or 7 mg metoprolol. Metoprolol reduced heart rate by 14% (P less than 0.001) and ventilation by 11% (P less than 0.01), but there was no significant difference in arterial O2 or CO2 tension (Pao2 and PaCO2, respectively). Metoprolol increased the time to exhaustion on a cycle ergometer (P less than 0.05) but did not improve the 12-min walking distance. A double-blind randomized crossover comparison of 4 wk treatment with atenolol (100 mg/day), metoprolol (100 mg/day), or matched placebo was performed in 12 patients with emphysema. Both beta-adrenoceptor antagonists reduced resting heart rate by 33% (P less than 0.001) and resting minute ventilation by 11% (P less than 0.025). There was no change in resting or exercise Pao2 or Paco2. During steady-state exercise on a cycle ergometer, atenolol and metoprolol reduced ventilation by 14 and 4%, respectively. This was accompanied by 11 and 5% reductions in O2 consumption (P less than 0.05) and 13 and 6% falls in CO2 production (P less than 0.05). There were no significant changes in tests of exercise tolerance, but forced expiratory volume in 1 s and forced vital capacity were reduced during beta 1-adrenergic blockade. beta 1-Blocking drugs reduce hyperventilation in emphysema by reducing pulmonary gas exchange without a change in arterial blood gas tensions. Increased airflow obstruction prevents this reduction being of therapeutic value.

Administration, Oral↗
PubMed1982

The selectivity of the beta-adrenoceptor for ventilation in man.

1 Minute ventilation, alveolar PCO2, CO2 production and heart rate were measured in eight normal subjects before and during infusions of noradrenaline 0.2, 1.0 and 5.0 micrograms min-1 and isoprenaline 0.04, 0.2 and 1.0 microgram min-1. 2 These measurements were repeated after propranolol 3.5 mg, atenolol 8 mg or metoprolol 7 mg by intravenous injection. 3 Noradrenaline 5.0 micrograms min-1 and isoprenaline 1.0 microgram min-1 significantly increased ventilation and CO2 production and decreased alveolar PCO2. These changes were attenuated by propranolol, atenolol and metoprolol. There was no significant difference between the blocking effects of the three beta-adrenoceptor blockers for these three variables but propranolol was more effective than atenolol or metoprolol in blocking isoprenaline induced tachycardia (P less than 0.001). 4 The hyperventilatory response to catecholamines is predominantly a beta1-effect.

Adrenergic beta-Antagonists↗
PubMed1982

Carbimazole and exercise tolerance in chronic airflow obstruction.

Ten patients with severe dyspnoea and chronic airflow obstruction entered a randomised double-blind crossover trial comparing the effect of carbimazole 80 mg daily for two months with that of placebo. Assessment of thyroid function, lung function, and exercise tolerance was performed monthly. The mean free thyroxine index after two months of carbimazole was significantly lower at 64.1 (+/- 10.5, SEM) than the 89.1 (+/- 3.8) while on placebo. Serum tri-iodothyronine was reduced and thyroid stimulating hormone raised while on the active drug. There was no significant difference in the 12-minute walking distance (TMD), the rating of perceived exertion during the TMD, the oxygen cost score, the dyspnoea grade, the resting arterialised capillary blood gas tensions or the resting minute ventilation. During a progressive exercise test to exhaustion on a cycle ergometer, there was no significant difference in the minute ventilation, heart rate, blood gas tensions at exhaustion, or the total work done. There were no symptoms or signs of hypothyroidism. Lung function (FEV1, FVC, TLC, KCO) was unchanged. Thus a 28% reduction in the free thyroxine index produced no symptomatic or objective benefit in exercise tolerance in patients with severe airflow obstruction. These results provide no support for the use of carbimazole in chronic airflow obstruction.

Carbimazole↗
PubMed1982

Propranolol uptake by dog lung: effect of pulmonary artery occlusion and shock lung.

First-pass lung uptake of propranolol in catheterized ambulant dogs was measured by comparison the difference between the ratios of [14C]propranolol to indocyanine green (ICG) before and after a single passage through the pulmonary circulation. Uptake was 56 +/- 5, 53 +/- 8, and 61 +/- 10% (mean +/- SD) when 0.02, 0.2, and 2.0 mg of propranolol were injected, respectively. There was a negative though unimportant correlation between percent uptake and cardiac output. Analysis of paired propranolol and ICG outflow curves confirmed the lack of saturation with increasing dose and suggested the involvement of simple diffusion. In four dogs uptake fell from 4.76 +/- 6.8 to 40.4 +/- 8.2% (0.05 greater than P greater than 0.025) during partial occlusion of the pulmonary circulation by a Swan-Ganz catheter balloon and rose again to 51.2 +/- 6.4% after relief of the occlusion. Propranolol uptake, measured serially in five dogs with indwelling catheters, was initially 55% but fell linearly to 30% over 2 wk (r = -0.59, P less than 0.001), and necropsy showed pathological features of shock lung. A similar study performed on three dogs within 4 days of catheterization showed no change in uptake of the drug. Propranolol uptake appears to reflect both quantitative and qualitative changes in the pulmonary endothelium. This method may therefore be valuable in studying the pulmonary endothelium in health and disease.

Animals↗
PubMed1982

Impaired lung uptake of propranolol in human pulmonary emphysema.

First-pass lung uptake of propranolol was studied in 10 patients with normal lungs, 8 patients with severe pulmonary emphysema, and 1 patient with primary pulmonary hypertension. Propranolol uptake was measured by comparing the ratio of [14C]propranolol (0.5 mg) to indocyanine green (5 mg) injected into the right atrium with the ratio of their concentrations in arterial blood collected over the duration of the first-pass dye outflow curve. Mean uptake was 69 +/- 4% (n = 18) in patients with normal lungs; 55 +/- 7% (n = 13) in patients with emphysema (p less than 0.001), and 51% in the patient with primary pulmonary hypertension. Cardiac index in the normal group (2.78 +/- 0.48 L/min/M2, n = 16) was not significantly different from the group with emphysema (2.90 +/- 0.48, n = 12). There was no correlation between lung uptake and conventional lung function indexes in patients with emphysema. We conclude that propranolol uptake is reduced when the pulmonary vascular bed is damaged. This may have pharmacologic consequences, and it is possible that other pharmacokinetic functions of the lung may similarly be impaired in pulmonary disease. The method is relatively simple, and may be suitable for assessing pulmonary endothelial function in patients with lung disease.

Adult↗
PubMed1981

First-pass lung uptake of propranolol enhanced in anaesthetized dogs.

Uptake of 14C-propranolol after a single passage through the pulmonary circulation was studied in three groups of Labrador dogs using a double indicator dilution method. Uptake in conscious, ambulant animals was 53%. This increased to 81% in dogs anaesthetized with thiopentone, nitrous oxide and halothane and to 64% in dogs anaesthetized with thiopentone, nitrous oxide and fentanyl. Interaction between lipid-soluble anaesthetic agents and pulmonary endothelial cell membranes may be an important factor in increasing lung uptake of lipophilic propranolol, although alteration in pulmonary perfusion associated with a reduction in cardiac output during general anaesthesia may play a part. The pharmacological effects of propranolol administered i.v. during general anaesthesia may be unpredictable.

Anesthesia, General↗