A multivariate study of some lung function tests at different age groups in healthy Indian males.

Considerable attempts have been made to study the changes in lung function in man in different age groups using univariate statistical techniques in which the lung function tests were assumed to be independent of each other. Actually the lung function tests are well correlated with each other and, thus, the inferences drawn on the basis of univariate statistical analysis may be misleading due to the violation of the assumption of independence. On the other hand, simultaneous changes in lung function in man in different age groups cannot be tested using univariate statistical techniques. Keeping in view such shortcomings of the univariate statistical techniques, an attempt has been made in the present investigation to study simultaneous changes in some lung function tests [viz. vital capacity (VC), forced vital capacity (FVC), forced expiratory volume for one second (FEV1), expiratory reserve volume (ERV), inspiratory capacity (IC) and maximum voluntary ventilation (MVV)] at different age groups (viz. 21-25, 26-30, 31-35, 36-40, 41-45, 46-50, 51-55, 56-60 and 61-70 years) in healthy Indian males using multivariate statistical techniques (viz. Wilks' statistic (A) and Mahalanobis' D2 statistic) for drawing valid statistical inferences. It is concluded that remarkable significant changes take place in lung function after the age of forty years.

Prediction of birth weight from simple anthropometric measurements in Indian male and female new born babies.

An attempt has been made in this paper to select suitable combination of predictors of birth weight from three anthropometric measurements (viz. length, head and chest circumferences) taken at birth of Indian male and female new born babies. The best combination of predictors was selected by examining the separate effects of each of the three concomitant variables on birth weight using the technique of multivariate regression analysis. The combination of head and chest circumferences was found to be the most appropriate for estimation of birth weight in view of the simplicity and non-invasiveness of measuring these two body circumferences. Keeping in view of the high multiple correlations, nomograms have been constructed to predict birth weights from head and chest circumferences in male and female new born babies. These nomograms will serve well as a simple and quick methods for predicting birth weight from head and chest circumferences in Indian male and female new born babies whenever the Direct weighing at birth is not feasible.

Efficacy of pentoxifylline with aspirin in the treatment of frostbite in rats.

The efficacy of pentoxifylline--a haemorrheologic agent along with aspirin--an analgesic agent was evaluated in the amelioration of the tissue damage due to experimentally induced frostbite in 5 groups (20 each) of rats with body weights ranging between 175 and 200 g. Frostbite was produced experimentally in the hind limbs by exposing the animals to -15 +/- 1 degrees C for 1 h using the harness technique, with simultaneous recording of rectal and environmental temperatures. The degree of tissue damage was assessed on the basis of tissue necrosis after 15 days. Administration of pentoxifylline (40 mg/kg bw) 30 min before and 30 min after the cold exposure followed by two doses of the same daily for the next 5 days along with aspirin (5 mg/kg bw) twice daily for the same duration only after cold exposure, resulted in significant improvement in the degree of tissue preservation. The findings of this preliminary study have brought to light the potential usefulness of these drugs in the treatment of frostbite. The combined pharmacological properties of these two drugs might have altered the haemorrheologic status of blood and produced the curative beneficial effect in improving tissue survival following experimentally induced frostbite in rats.

Fit of Ehrenberg's equation to height & weight of young healthy Indian males.

Height-weight relationship in young healthy Indian males (16-21 yr) has been established for different states of India as well as for the combined data of all the states. It was observed that these relationships have large deviations of the intercepts and slopes from the intercept (a = 0.4) and slope (b = 0.8) of the Ehrenberg's equation. The results of the present study show that Ehrenberg's equation may not be applicable for young healthy Indian males aged 16-21 yr.

Experimental studies on the treatment of frostbite in rats.

The effect of treatment by high dose of vitamin C, rapid rewarming by 37 degrees C water alone and with vitamin C, rapid rewarming by 37 degrees C decoction of Indian black tea alone and with vitamin C for experimentally produced frostbite was evaluated in 6 groups (25 each) of rats. Frostbite was produced experimentally in the hind limbs by exposing the animals at -15 degrees C for 1h using the harness technique. The degree of injury was assessed and classified on the basis of tissue necrosis at the end of 15 days. Administration of high dose of vitamin C for prolonged period and rapid rewarming at 37 degrees C water bath immediately after cold exposure apparently reduced the tissue damage. High dose of vitamin C therapy preceded by rapid rewarming in plain water showed additional benefit. Rapid rewarming in decoction of Indian tea resulted in identical beneficial effect. The degree of tissue preservation was highest with rapid rewarming in tea decoction followed by high dose of vitamin C.

Height-weight relationship in young healthy Indian girls.

The relationship between height and weight in young healthy Indian girls (8--18 years) was developed. It is concluded that the relationship of the form:log w = 0.98 h + 0.14 holds good to the data on height h (in metres) and weight w (in kilograms) for this group of subjects, the logarithm is taken to the base 10. The results of the present study show that Ehrenberg's equation of the form : log w = 0.8 h + 0.4 may not be extended upto the age of 18 years in young healthy Indian girls.

Height-weight relationship in young healthy Indian males.

Height-weight relationship in young healthy Indian males (19-22 yrs.) has been established. It is concluded that the relationship of the form: log w = 1.18 + 0.35 h fits well to the data on height h (in metres) and weight w (in kilograms) for this group of subjects, the logarithm is taken to the base 10. The results of the present study show that Ehrenberg's equation of the form: log w = 0.8 h + 0.4 cannot be extended beyond the age of 18 years in young healthy Indian males.

Prediction of some ventilatory 'norms' in healthy Indian males 21-69 years age.

This paper presents regression equations for predicting some ventilatory 'norms' (viz. vital capacity, forced vital capacity, forced expiratory volume for one second, expiratory reserve volume, inspiratory capacity and maximum voluntary ventilation) from physical characteristics of healthy Indian males. These equations have been constructed on the basis of multivariate regression analysis of the data of ventilatory 'norms' and physical characteristics collected on 171 healthy Indian males of age ranging from 21-69 years. Applications of these regression equations will be of practiced importance to biomedical scientists interested in the indirect assessment of ventilatory 'norms for a wider age range (21-69 years) which has not been covered by earlier studies carried out in this direction.

Fitting curves to physiological data.

This paper deals with fitting of a parabola and three parameter logistic curve to relate heart output and initial index finger temperature with ambient temperature in human subjects. The coefficients of determination (R2%) between observed and estimated values of heat output and initial index finger temperature were close to 98% indicating the high percentage of variation of the total sum of squares absorbed by the fit of the curves. The superiority of the fitted curves over the other curves have been proved. Thus it is concluded that parabola and three parameter logistic curve may explain the relationships of heat output and initial index finger temperature with ambient temperature more precisely than other curves.

Gompertz curve in physiology: an application.

Gompertz curve has been successfully used to estimate mortality intensities, recovery and relapse rates for human beings suffering from specific diseases. Perhaps, no attempt has yet been made to describe statistically the phenomenon of thermoregulation efficiency of man. This paper deals with the statistical approach for describing the above mentioned phenomenon. For this purpose, Gompertz curve has been fitted to the data of recovery palm skin temperature of human subjects, which was collected after removing the hand of a subject dipped for two minutes in cold water maintained at 10 +/- 1 degree C on seven environmental situations including altitude. The coefficients of correlation between observed and estimated palm skin temperature expressed logarithmically were close to 0.99 for each situation indicating the high precision of the fitted curve. The average rates of recovery of palms skin temperature have also been compared between these seven environmental situations using analysis of covariance technique. It is concluded that recovery of palm skin temperature of sea level residents during stay at plains is much faster than their recovery at high altitude situations.

Endurance capacity for continuous effort in terms of aerobic and anaerobic fraction of oxygen supply.

Studies have been conducted on 13 young healthy adults of average fitness on endurance work of varying durations lasting for 2-31 minutes using bicycle ergometer. Aerobic-anaerobic fractions of oxygen supply during each effort was determined. The data from Astrand and Rodahl on aerobic O2--supply and duration in maximal efforts from 1-120 minutes on a highly trained subject have also been considered. The plot of log endurance time against log (aerobic/anaerobic ratio) exhibits a slight departure from linearity, indicating independent contributions from aerobic and anaerobic fractions of oxygen supply. An equation was derived of the form: T - Au1k1u2--k2 where u1 end u2 are the aerobic and anaerobic fractions respectively which has been found to yield highly significant correlation coefficient between log-estimated and log-observed endurance time (0.9996 for Astrand and Rodahl's data on a single subject and 0.9640 for the present data on 13 subjects). This index is, therefore, quite suitable for the assessment of endurance capacity in terms of a single physiological parameter, and is likely to be superior to indices in current use.

Lognormal distribution in physical work capacity in young healthy males.

This paper evaluates the statistical distribution of physical work capacity (Vo2 max) in young healthy males. For this purpose, the normally of Vo2 max data, collected on two random samples consisting of 123 and 120 young healthy male volunteers was tested. It is concluded that physical work capacity follows lognormal distribution and the quality of fit has been found to be good as tested by chi2 test.