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Biomedical subjects

K G Chetty

Publications and source records attributed to K G Chetty.

29 records · Page 2Linked to original sources
PubMed1983

Comparison of the effects of labetalol and hydrochlorothiazide on the ventilatory function of hypertensive patients with mild chronic obstructive pulmonary disease.

Labetalol is a new adrenergic antagonist with both alpha- and beta-blocking effects. The effects of labetalol and hydrochlorothiazide on the hypertension and ventilatory function of patients with both hypertension and mild reversible chronic pulmonary disease were compared. In this double-blind study, 20 patients were randomly allocated to receive increasing doses of labetalol (100 to 400 mg three times a day) or hydrochlorothiazide (25 to 50 mg three times a day) over a four-week treatment period. Patients returned at weekly intervals for spirometry baseline, two hours after receiving the medication for the following week, and five minutes after an exercise test. Each treatment reduced the blood pressure significantly and to a comparable degree. There was no significant decrease in ventilatory function two hours after administration of the drug at any visit for either drug. Ventilatory function did not deteriorate significantly following exercise with either drug. With labetalol there was a progressive statistically significant decline in baseline forced expiratory volume in one second from 1,860 +/- 190 ml to 1,685 +/- 190 ml during the four-week study period, although no patient became symptomatic from shortness of breath. We conclude that labetalol is an effective antihypertensive agent that does not adversely effect ventilatory function immediately, but that may lead to a decline in ventilatory function when administered long-term.

Aged↗
PubMed1983

Uncoupling of oxidative phosphorylation in rat liver mitochondria following the administration of dimethyl sulphoxide.

A single intraperitoneal injection of 275 mg of dimethyl sulphoxide (DMSO) to rats (100-125 g body weight) effectively uncouples oxidative phosphorylation in liver mitochondria during the period from 2 hr to 5 day post-injection. Higher doses of DMSO are inhibitory to mitochondrial respiration. DMSO has however no uncoupling action on oxidative phosphorylation in vitro. On the other hand, dimethyl sulphide (DMS), a known metabolite of DMSO, brings about the uncoupling effect in vitro. The uncoupling of oxidative phosphorylation by normal mitochondria could also be achieved if these are pre-incubated (30 min at 0 degrees C) with the post-mitochondrial liver supernatant derived from rat injected with DMSO, 2-24 hr prior to sacrifice. These results provide explanation for the observed uncoupling effect exerted by DMSO in vivo.

Animals↗
PubMed1983

Improved exercise tolerance of the polycythemic lung patient following phlebotomy.

The present study evaluated the effects of therapeutic phlebotomy on the exercise tolerance and the maximal carbon dioxide output of polycythemic patients with chronic obstructive pulmonary disease. Fifteen maximal exercise studies were performed before and after phlebotomy in patients with moderate to severe chronic obstructive pulmonary disease (mean forced expiratory volume in one second [FEV1]= 970 ml). After phlebotomy there were no significant differences in pulmonary function, blood gases, oxygen consumption, or carbon dioxide production at rest. However, after phlebotomy there was a significant increase in the exercise tolerance of the patients. The mean workload, the duration of exercise, the maximal oxygen consumption, the maximal carbon dioxide production, and the ventilation at maximal exercise all increased significantly. The improved exercise tolerance after phlebotomy appeared due to an increased cardiac output generated mainly through an increased stroke volume. We hypothesize that the increased stroke volume was due to a higher ejection fraction of the right ventricle secondary to a lower pulmonary artery pressure. This study provides further evidence that patients with chronic obstructive pulmonary disease who have polycythemia benefit by therapeutic interventions that maintain their hematocrits below 55 percent.

Aged↗
PubMed1982

Identification of pulmonary hypertension in chronic obstructive pulmonary disease from routine chest radiographs.

The mean pulmonary artery pressure (PAP) was measured in 34 patients with moderate to severe chronic obstructive pulmonary disease (FEV1, 1,010 +/- 460 ml)) and was correlated with the following 3 indexes derived from the chest roentgenogram: (1) the hilar thoracic index, (2) the diameter of the descending branch of the right pulmonary artery, (3) the hilar width, and (4) the cardiothoracic ratio. The mean PAP was 29.0 mm Hg and 20 of 34 patients had an elevated mean PAP (greater than 20 mm Hg). Nineteen of the 20 patients (95%) with an elevated mean PAP had a hilar thoracic index of 36 or above, whereas none of the 14 patients with a normal mean PAP had a hilar thoracic index above 35. Nineteen of the 20 patients (95%) with an elevated mean PAP had diameters of the descending branch of their right pulmonary artery of 20 mm or more compared with only 3 of 14 patients (21%) with a normal mean PAP. The PAP best correlated with the hilar thoracic index (r = 0.74, p less than 0.01) and was significantly correlated with the other 3 indexes. However, the accuracy with which the PAP could be predicted was only +/- 21 mm Hg. We conclude that the chest radiograph is useful in screening patients with COPD for elevated PAP, but that it cannot be used to predict the PAP accurately.

Forced Expiratory Volume↗
PubMed1977

Suspected superior vena cava syndrome: the role of the Swan-Ganz catheter.

The use of the Swan-Ganz flow-directed catheter in establishing the diagnosis of the superior vena cava syndrome in two patients (one with Hodgkin's disease and the other with carcinoma of the lung) is described. A pressure tracing showing elevated pressure above the obstruction without respiratory or cardiac fluctuations is characteristic of obstruction of the superior vena cava.

Adenocarcinoma↗
PubMed1976

Mechanisms underlying decreased protein and RNA synthesis in the rat spleen following whole-body X-irradiation.

Whole-body exposure of rats to 1000 R X-rays resulted in decreased rates in protein and RNA syntheses in the spleen from the fourth post-irradiation hour. These changes correspond well with impaired ability of nuclei to polymerise RNA, reduction in template efficiency of chromatin, decrease in the activity of RNA polymerase and inhibition in histone phosphorylation. Protection of the spleen by lead shielding during whole-body exposure to X-rays largely eliminated the observed alterations in protein and nucleic acid synthetic machineries. This suggests that the radiation-induced inhibition in protein and RNA syntheses is mainly due to the direct action of radiation on the spleen itself.

Animals↗