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Biomedical subjects

T G Radha

Publications and source records attributed to T G Radha.

8 recordsLinked to original sources

Effect of hypoxia on regional lung perfusion, by scanning.

Lung scanning was performed in 12 subjects who had pulmonary oedema of high altitude (POHA) before, and in 8 men who had been at high altitude without developing pulmonary oedema. Scanning done before and after 5 min 10% O2 breathing showed (a) increased perfusion in POHA subjects after hypoxia, (b) more in the lower than in upper zones, and (c) striking increase in perfusion in localised areas. In controls, however, there was significant reduction in perfusion after hypoxia in most areas. The reduction was less marked in the lower zones than in the upper zones. POHA subjects were hyperreactors to hypoxia, compared to controls. It is concluded that scanning before and after hypoxic breathing might help in differentiating hyperreactors.

Humans

Allergic bronchopulmonary aspergillosis.

Allergic bronchopulmonary aspergillosis (ABPA) is not a common condition, even though asthma due to sensitization to Aspergillus antigen is very common in many countries because of the ubiquitous distribution of the fungus itself. During the course of 14 years, the Mycology Department of the V. P. Chest Institute, Delhi, has confirmed the diagnosis of ABPA in 46 patients. The present study is based on the follow-up of 17 patients for understanding the evolution of the disease. All of them had Aspergillus fumigatus (AF) in the sputum with positive type I and type III skin reaction to AF antigen. 7 patients were treated for 10 days with oral administration of Hamycin, an antibiotic isolated from one of the streptomycete species. Immediate results were very good, with marked alleviation of subjective symptoms and absence of fungi in the sputum. The drug deserves further trial.

Adult

Further studies on pulmonary oedema of high altitude. Abnormal responses to hypoxia of men who had developed pulmonary oedema at high altitude.

101 Indian soldiers, 57 of whom had developed pulmonary oedema of high altitude (POHA) and 44 who had not developed this condition in spite of being at high altitudes for over 2 years, were investigated for observing the differences, if any, in their reaction to acute hypoxic stress. Each subject was made to breathe a 10% hypoxic mixture for 5 min. Haemodynamic parameters like pulmonary artery pressure (systolic, diastolic and mean), brachial artery pressure, wedge pressure, cardiac output, minute ventilation, arterial oxygen saturation and oxygen uptake before and at the end of hypoxic breathing were estimated. In addition, results of the cold pressor test were recorded and the Vd/Vt ratio was estimated. The results obtained in the present study confirmed those obtained in our previous studies. In addition, it was observed that oxygen uptake was significantly higher and oxygen saturation lower after hypoxia in the POHA subjects than in the controls. Certain parameters for screening of subjects possibly susceptible to POHA have been suggested.

Adult

Effect of acute hypoxia on blood serotonin in human beings and rats.

The object of this study was to see if the blood level of 5-hydroxytryptamine (5-HT) increased under acute hypoxic stress in human beings and rats. Soldiers who had been stationed at high altititudes 2-7 months prior to study were selected. 17 had suffered from pulmonary oedema and the remaining eight, who had not developed the condition, acted as controls. The technique of YUWILER [18] with suitable modifications was used for estimation of 5-HT. No significant change in 5-HT levels was observed either in subjects or controls. Rats exposed to simulated high altitude for 6 h also did not show any significant change in blood 5-HT levels.

Altitude

Pulmonary vascular response to ventilation hypercapnia in man.

The effect of ventilation hypercapnia on pulmonary circulation in man was investigated through separate studies. In the first study on 44 patients with little or no airway obstruction and 20 normal men, 5% CO2 breathing produced (a) significant rise in pulmonary artery pressure (PAP), (b) no significant change in cardiac output, (c) rise in pulmonary vascular resistance, (d) rise in brachial artery pressure (BAP) and (e) no change in wedge pressure (WP). The rise in PAP was more pronounced after 2 min of 10% CO2 breathing in 12 bronchitics. The scond study was carried out in 39 bronchitics and 22 normals while breathing 10% CO2 for 1 min and showed that pulmonary vascular response was independent of systemic vascular response, in that BAP rose later and came back earlier to original level during CO2 breathing. In the third study on 26 severe bronchitics and 15 normals the observed rise in PAP during 10% CO2 breathing was independent of H-ion concentration in the blood since PAP continued to rise even when pH was maintained at air breathing level by intravenous injection of 130 mEq of sodium bicarbonate in 250 cm3 of 5% glucose solution. This study also confirmed the findings in the first study that there was minimal rise in cardiac output, no rise in WP, while PAP and pulmonary vascular resistance rose significantly during ventilation hypercapnia. The responses were pronounced compared with those observed in the first study with 5% CO2. It is postulated that the responses might be due to direct action of CO2 on muscular pulmonary arteries.

Bicarbonates