Helium/oxygen flow volume curves in normal Indian males > 50 year, and the effect of bronchodilator aerosols on airflow variables in this subject group.

Fourteen healthy males (mean age 54.7 yr) described maximal flow volume curves after Air breathing (AB) and after inspiring 10 deep breaths of a mixture of 80% Helium/20% Oxygen (He/O2). Vmax 50% FVC as obtained from the AB curves was 3.11 +/- 1.27 lps, and this increased by 38.1 +/- 17%, with He/O2. The Vmax 50% He-O2/Air ratio was 1.32 +/- 0.17, while the V iso V was 1.1 +/- 0.35 liters (30.9% of the FVC). Inhalation of 80 micrograms (4 puffs) of Ipratropium bromide, a vagolytic aerosol, or salbutamol (200 micrograms; 2 puffs), a beta 2 adrenergic stimulant did not alter the He/O2 curves significantly. As another aspect of the study, airflow variables viz. Vmax 50% of the FVC, Vmax 25%-75%, and Vmax 25% were measured from the AB curves, and the effect of bronchodilator aerosols was investigated in order to evaluate the degree of control of the bronchomotor tone by either the adrenergic receptors, or the vagus. Only the Vmax 25%-75% increased significantly with Salbutamol administration. While the degree of increase brought about by salbutomol aerosol for all of the variables under investigation was more than that seen with ipratropium br., the difference in this increase between the two bronchodilators used was not significant. The result may indicate that almost an equivocal influence is exerted by the two arms of the autonomic nervous system on bronchomotor tone in middle aged normal males, and that a more sensitive test (viz He-O2 breathing) does not elucidate this any further.

Cardiovascular responses to phenylephrine during acute experimental anaemia in anaesthetized cats.

Experiments were performed on anaesthetized artificially ventilated cats to study the effects of phenylephrine (PE) on cardiovascular responsiveness, before and after induction of experimental anaemia. Acute anaemia was induced by replacement of blood by dextran in three steps of 20% each of total estimated blood volume. The effect of PE (20 micrograms/kg) was investigated at four stages: control and after 1st, 2nd and 3rd exchanges of blood. Induction of anaemia produced a significant increase in heart rate (HR) and cardiac output (CO) and a decrease in right atrial pressure (RAP). No significant change in mean arterial pressure (MAP), LV dP/dt max and blood gas tension was observed. Administration of bolus dose of PE produced a rapid rise in MAP, LVdP/dt max, and a decrease in HR without a change in the RAP. The pattern of response to PE was similar after induction of acute anaemia, however the magnitude of the response was significantly reduced. The attenuation in the response to PE was related to the fall in the haematocrit (HCT) level. This shows that induction of experimental anaemia, produced an increase in CO due to an increase in HR and SV and the effect of PE on cardiovascular responsiveness was significantly attenuated. The reduced sensitivity to PE during acute anaemia could be due to many factors such as inadequate O2 supply, effect of local vasodilating agents or some other cardiotonic agents which are known to contribute to vascular responsiveness.

On the contribution of height to predict lung volumes, capacities and diffusion in healthy school children of 10-17 years.

Lung volumes, capacities, diffusion and alveolar volumes with physical characteristics (age, height and weight) were recorded for 186 healthy school children (96 boys and 90 girls) of 10-17 years age group. The objective was to study the relative importance of physical characteristics as regressor variables in regression models to estimate lung functions. We observed that height is best correlated with all the lung functions. Inclusion of all physical characteristics in the models have little gain compared to the ones having just height as regressor variable. We also find that exponential models were not only statistically valid but fared better compared to the linear ones. We conclude that lung functions covary with height and other physical characteristics but do not depend upon them. The rate of increase in the functions depend upon initial lung functions. Further, we propose models and provide ready reckoners to give estimates of lung functions with 95 per cent confidence limits based on heights from 125 to 170 cm for the age group of 10 to 17 years.

Biological standardization of pollen allergens from India.

Standardization of allergens are achieved by in vitro and in vivo methods. Some of the allergens from Western countries are standardized using biological potency of the extracts but no attempt has been made till now to standardize any of the pollen extracts from India based on biological units. Therefore, we have attempted to standardize two important pollen allergens Ricinus communis and Holoptelea integrifolia by biological methods. Broadly the methods adopted by Dreborg and Grimmer (1983) was followed. Skin prick tests were carried out with the extracts of R. communis and H. integrifolia on 15 allergic patients in five three fold log dilutions starting with 1:10, in 50% glycerinated buffer. Glycerinated buffer (50%) and histamine dihydrochloride (1 mg/ml) were used as negative and positive controls, respectively. The mean wheal diameter obtained with different concentrations showed a gradual systematic fall with increase in dilution. The mean relative diameter (% of histamine reaction) varied from 124.1 +/- 8.9 to 33.7 +/- 6.1 and 78.9 +/- 5.5 to 21.4 +/- 3.8 with the highest and lowest concentrations of R. communis and H. integrifolia pollen antigens, respectively. The histamine equivalent concentration of antigen 1,000 Biological Units (BU) obtained for crude pollen extracts of R. communis and H. integrifolia was 1:17 and 1:22 respectively.

Evaluation of filarial skin test with Brugia malayi larval antigen in the field.

To obtain comparable and reproducible results by filaria skin test with B. malayi larval antigen, standard procedure has been evolved. Antigen protein of 2 micrograms per test, injected intracutaneously, was found optimum for positive skin reaction. The reaction ratio based on increase of wheal area by 2 times or more was found to be statistically significant for interpreting positive results. However, in larger field trials, the simpler measurement of increase of wheal diameter by 1 1/2 times or more was found to be equally reliable. Patients treated with diethylcarbamazine citrate, antihistaminics and anti-inflammatory drugs are likely to be unresponsive to filarial antigen and will yield incorrect information.