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Biomedical subjects

J F Bedi

Publications and source records attributed to J F Bedi.

At least 37 records · Page 2Linked to original sources
PubMed1985

Pulmonary response to threshold levels of sulfur dioxide (1.0 ppm) and ozone (0.3 ppm).

We exposed 22 healthy adult nonsmoking male subjects for 2 h to filtered air, 1.0 ppm sulfur dioxide (SO2), 0.3 ppm ozone (O3), or the combination of 1.0 ppm SO2 + 0.3 ppm O3. We hypothesized that exposure to near-threshold concentrations of these pollutants would allow us to observe any interaction between the two pollutants that might have been masked by the more obvious response to the higher concentrations of O3 used in previous studies. Each subject alternated 30-min treadmill exercise with 10-min rest periods for the 2 h. The average exercise ventilation measured during the last 5 min of exercise was 38 1/min (BTPS). Forced expiratory maneuvers were performed before exposure and 5 min after each of the three exercise periods. Maximum voluntary ventilation, He dilution functional residual capacity, thoracic gas volume, and airway resistance were measured before and after the exposure. After O3 exposure alone, forced expiratory measurements (FVC, FEV1.0, and FEF25-75%) were significantly decreased. The combined exposure to SO2 + O3 produced similar but smaller decreases in these measures. There were small but significant differences between the O3 and the O3 + SO2 exposure for FVC, FEV1.0, FEV2.0, FEV3.0, and FEF25-75% at the end of the 2-h exposure. We conclude that, with these pollutant concentrations, there is no additive or synergistic effect of the two pollutants on pulmonary function.

Adult↗
PubMed1984

Pulmonary function changes after 1 h continuous heavy exercise in 0.21 ppm ozone.

Prediction equations developed from previous ozone (O3) exposure studies suggested that athletes exercising at near competitive intensities would be subject to alteration of pulmonary function during exposure to relatively low concentrations of O3. Accordingly we exercised seven trained athletes for 1 h at 75% of maximal O2 consumption in both room air and a 0.21 ppm O3 environment. Pulmonary function tests, including forced expiratory maneuvers and maximum voluntary ventilation (MVV), were performed prior to and immediately following the 1-h test. Significant decreases in forced vital capacity (FVC, -7%), forced expired volume in 1.0 s (-15%), forced expiratory flow over the midhalf of FVC (-18%), and MVV (-17%) were recorded following O3 exposure. The magnitudes of these changes are similar to those observed in subjects performing moderate intermittent exercise for 2 h in a 0.24 ppm O3 environment. Symptoms reported following O3 exposure included laryngeal and/or tracheal irritation and soreness and chest tightness on taking a deep breath. The observed alterations in lung functions in these subjects indicate that individuals performing heavy continuous exercise are more likely to be affected by lower O3 levels.

Adolescent↗
PubMed1984

Interaction of peroxyacetyl nitrate and ozone on pulmonary functions.

The metabolic and pulmonary function effects were investigated in 10 nonsmoking, young adult men who were exposed for 2 h (20 degrees C (wet-bulb globe temperature) (WBGT] to 4 conditions: (1) filtered air (FA), (2) 0.30 ppm peroxyacetyl nitrate (PAN), (3) 0.45 ppm ozone (O3), and (4) 0.45 ppm O3 + 0.30 ppm PAN (PAN/O3). The subjects alternated 15-min periods of rest and 20-min periods of bicycle ergometer exercise at a work load predetermined to elicit a ventilatory minute volume (VE) of 27 L/min (BTPS). Functional residual capacity (FRC) was determined pre- and postexposure. Forced vital capacity (FVC) was determined before and after exposure, and 5 min after each exercise period. Heart rate was monitored throughout the exposure, and (VE), oxygen uptake (VO2), respiratory rate (fR), and tidal volume (VT) were measured during the last 2 min of each exercise period. There were no changes in any variable consequent to FA or PAN exposure. The only metabolic changes to occur because of O3 and PAN/O3 exposure were a decrease in VT, a concomitant increase in fR, and consequently no change in VE. Both O3 and PAN/O3 induced significant (p less than 0.05) decrements in FVC, FEV1.0, FEV2.0, FEV3.0, FEF25-75%, IC, ERV, and TLC. The decrements after PAN/O3 exposure averaged 10% greater than the decrements after O3 exposure. The results suggest an interactive effect between PAN and O3, possibly explained by total oxidant load.

Acetates↗
PubMed1983

Exercise respiratory pattern in elite cyclists and sedentary subjects.

We investigated the breath-by-breath pattern of ventilatory response to bicycle exercise in seven elite male cyclists (VO2max = 71.7 ml X min-1 X kg-1) and ten sedentary males (VO2max = 47.3 ml X min-1 X kg-1) to analyze differences in breathing patterns between individuals with normal and high exercise ventilations (VE). The mean VEmax of the athletes (ATH) exceeded that of the sedentary subjects (SED) by 34.6% (183 vs 136 l X min-1) and was proportional to the difference in VCO2max between the groups (5.9 vs 4.23 l X min-1). The ATH used an average of 89% of their 15-s maximum voluntary ventilation (MVV) during maximum exercise while SED used only 71%. The ATH had slightly, but not significantly, larger vital capacity (FVC). Both groups used about half of their FVC at maximum tidal volume (VT), VT was 47% and 49% of FVC in ATH and SED, respectively. The ATH achieved the higher VEmax by achieving a greater increase in respiratory frequency (63/min vs 49/min), which was accomplished by significant decreases in both inspiratory (T1) and, more importantly, expiratory (TE) time. There was a tendency for athletes to have a somewhat more regular breathing pattern. Both 1/T1 and mean inspiratory flow (VT/T1) were highly correlated with VE, but there were no differences in these relationships between ATH and SED. Highly-conditioned athletes, therefore, respond to the increased demand for CO2 elimination by utilizing a higher respiratory frequency achieved through a reduction of both inspiratory and expiratory duration, but not by utilizing a larger tidal volume (i.e., as percent FVC) than less fit individuals.

Adult↗
PubMed1983

Ocular functions and incidence of acute mountain sickness in women at altitude.

The effects of altitude on a series of ocular functions were studied on seven expedition members, all women aged 23-53 years, during the first ascent of the 6798-m peak Brigupanth in the Indian Himalayas. The only consistent change was a decrease in convergence amplitude. The amplitude of accommodation remained stable among the younger climbers, but decreased markedly among the older ones as higher altitudes were reached. There also appeared to be a lessened vascular reactivity to the hypoxia of altitude in the older members. Stereoscopic vision was unimpaired at all altitudes tested and extra-ocular muscle balance remained unaffected in all but two members who had an increase in their baseline phorias. Two of the summit climbers developed retinal hemorrhages. There was an average weight loss of 5.4 kg during the climb, but general health was good. Symptoms of acute mountain sickness were noted infrequently, and there were only moderate changes in the menstrual cycle.

Adult↗
PubMed1982

Human exposure to sulfur dioxide and ozone in a high temperature-humidity environment.

In order to examine the role of high temperature and humidity in the possible synergistic action of ozone and sulfur dioxide on human pulmonary function previously reported by some investigators and repudiated by others, we randomly exposed eight healthy young male nonsmokers to filtered air, 0.4 ppm SO2, 0.4 ppm O3, and 0.4 ppm SO2 plus 0.4 ppm O3 at 35 degrees C--85% rh for 2 hours. Subjects exercised for 15 minutes of each half hour at a workload sufficient to elicit a minute ventilation of 30 liters (BTPS). Pulmonary function tests were performed prior to, during, and following exposure. Observed alterations in pulmonary functions in the SO2 + O3 exposure reflected the changes occurring during the O3 exposure, clearly indicating that no synergistic effects related to the additional presence of SO2 were evident in this study. We considered factors suggested as causes for a potential synergism in comparing the conflicting studies on O3 and SO2, and suggest that factors other than temperature-humidity and/or sulfate aerosol production must be sought.

Adult↗
PubMed1982

Sweating sensitivity and capacity of women in relation to age.

Ten postmenopausal and ten younger women rested for 2 h in a 40 degrees C, 22.2-Torr vapor pressure environment. Sweating response was monitored by resistance hygrometry for onset, a platform balance for whole-body sweat rate, and five individual capsules for regional sweat rate. Other variables measured included forearm blood flow, heart rate (HR), mean skin (Tsk) and rectal (Tre) temperatures, sweat electrolytes (Na+ and K+), oxygen uptake, and plasma volume changes. Preliminary tests included maximal aerobic power (VO2max) and percent body fat. Heat stress did not elicit any significant differences in sweating response between age groups. Indices of heat strain, Tre and HR, were also similar for both groups. The only significant difference between younger and older women was a higher Na+ concentration in the forearm sweat of postmenopausal women. No thermoregulatory responses were related to age, but both sweat rate (r = 0.48) and peak Tsk (r = -0.43) were related to VO2max. For healthy, active, older women aging did not diminish the functional capacity of the sweating mechanism to cope with heat stress while resting in this specific thermal environment.

Adult↗
PubMed1982

Women at altitude: cardiovascular responses to hypoxia.

Six women mountaineers, 23-43 years of age, participated in a series of physiological tests prior to and during an expedition to Bhrigupanth (6798 m) in the Indian Himalayas. During a three-phase step test at sea level, carrying 0, 4.5, and 9.0 kg backpack weights, oxygen requirements represented 49.5-54.8% VO2 max. Recovery heart rates (HR) at 5-15 s were linearly related to exercise HR. At 4250 m, 5-15 s postexercise HR's were significantly higher than those at SL but returned to SL values after 3 min of rest. At 5000 m, HR's remained higher than those at SL throughout recovery. On returning to 4250 m after 3 weeks at higher altitudes, all postexercise HR's were back to SL levels. Supine HR's, higher at altitude than at SL during the ascent, returned to SL rates on return to 4250 m. Hemoglobin and hematocrit increased from 13.7 mg% and 42.4% at SL to 16.4 mg% and 52.6% after the climb. Resting blood pressure was significantly elevated at 4250 m during ascent but returned to SL values on the descent. During the cold pressor test, systolic pressure was unaffected by altitude; diastolic pressure increased less at altitude. While HR was unchanged at SL, a significant increase in HR was observed in postclimb CPT tests, even though perceived discomfort decreased.

Acclimatization↗
PubMed1981

Combined effects of ozone and nitrogen dioxide on respiratory function in man.

Ten young adult males were exposed to either filtered air or 0.50 ppm ozone plus 0.50 ppm NO2 in filtered air under four environmental conditions: 25 degree C, 45 % rh; 30 degrees C, 85% rh; 35 degrees C, 40% rh; and 40 degrees C, 50% rh. There were eight 2-hour exposures per subject. After 1 hour of sitting exposure the subjects exercised for 30 minutes (35-40% predicted maximum capacity) which increased ventilatory exchange to approximately 40 L/min (BTPS). Pulmonary function tests were performed before, during, and after exposure. Metabolism and ventilation were determined during the last 15 minutes of exercise. A symptom questionnaire was completed at the termination of each exposure following reexamination by a physician. There was a decrease in vital capacity, inspiratory capacity, and several flow-related measures of lung function during exposure. The response to exposure to the combined pollutants (O3 and NO2) was similar to that observed in ozone exposures alone. No synergism was observed.

Adult↗
PubMed1980

Respiratory responses in humans repeatedly exposed to low concentrations of ozone.

The effect of repeated daily exposure to a low concentration of ozone was studied in healthy adult males to answer 2 questions: (1) Is there a cumulative effect of exposure to ozone from day to day, causing an exacerbation of changes in pulmonary function? (2) Does the subject develop resistance or adaptatin to the respiratory effects of ozone? The subjects were exposed for 2 h in an environmental chamber at 35 degrees C and 45% relative humidity to filtered air on day 1, to ozone on days 2 through 4, and to filtered air on day 5. Three groups of subjects were used, each exposed to a different concentration of ozone: group 1 (n = 10), 0.20 ppm of ozone; group 2 (n = 10), 0.35 ppm of ozone; group 3 (n = 8), 0.50 ppm of ozone. There were no acute or cumulative effects of repeated exposure to 0.20 ppm of ozone. With exposure to 0.35 ppm of ozone, there were decrements in forced expiratory parameters on day 2. These changes were greater on day 3, but wre largely absent on days 4 and 5. In group 3, there were marked effects of ozone on pulmonary function on day 2, but these changes were greatest on day 3. Significant effects (although of lesser magnitude) were also observed on day 4. The forced expiratory volume in 1 s decreased 8.7% on day 2, 16.5% on day 3, and 3.6% on day 4. The subjects claimed the most discomfort on day 3; many noted marked improvements on day 4, the third consecutive day of exposure to ozone. Two additional subjects were exposed to 0.50 ppm of ozone for 4 consecutive days. Although effects of ozone on pulmonary function were observed on the first 2 days of exposure, few effects were seen on the third day, and no effect was observed on the fourth day. We conclude that there is some short-term cumulative effect of exposure to concentrations of ozone above the threshold for producing acute respiratory effects. This is followed by a period of resistance or adaptation in which there is a marked lessening of the effect of ozone on pulmonary function and on the subjective feelings of discomfort associated with exposure to ozone.

Adolescent↗
PubMed1979

Response of women mountaineers to maximal exercise during hypoxia.

Eight members of the American Women's Himalayan Expedition, ranging in age from 20-49, performed maximal exercise on a treadmill under normoxic and acute hypoxic (12.58% O2) conditions. Normoxic values for VO2 max were above average for all subjects and did not decline with age. The mean decrease in VO2 max (26.7%) during hypoxia was equivalent to that reported for younger males, which suggests that age was not a factor in response to hypoxia. Maximal heart rate, respiratory exchange ratio, oxygen pulse, and walk time were lower in hypoxia while ventilatory equivalent and blood lactate were higher. VEmax BTPS, was the same under both conditions. The combination of laboratory results and field observations by the Expedition physician suggest that women are capable of performing hard work at high altitude if they are in good condition and properly acclimatized.

Adult↗
PubMed1978

Hypoxia, smoking history, and exercise.

Six nonsmokers and six cigarette smokers, 22-34 years old, performed bicycle work (53% sea level VO2 max) for 30 min in an altitude chamber under four conditions: SL, simulated sea level (PIO2 = 159 torr, PB = 523 torr) with 0.5% HbCO; SLCO, simulated sea level with 4.2% HbCO; and ACO, altitude with 4.2% HbCO. During work at altitude, heart rate (HR), minute ventilation and tidal volume increased and diastolic blood pressures decreased relative to SL. Cardiac output (Qc), stroke volume (SV), and arterial-mixed venous oxygen difference (a--vO2) were similar in smokers and nonsmokers at SL, SLCO, and A. At ACO, nonsmokers increased Qc and SV and decreased a--vO2, but these were not influenced in the smokers. Smokers showed a graded increase in HR when exposed to work in SLCO, A, and ACO. Their lower finger temperatures during A and ACO suggested vasoconstriction in the extremities. Cigarette smokers may be partially adapted to hypoxia.

Adult↗
PubMed1977

Influence of exercise and heat stress on pulmonary function during ozone exposure.

We studied the effects of a 2-h exposure to ozone (0.5 ppm) in 14 nonsmoking males under four environmental conditions (WBGT (wet bulb-globe temperature index) = 64.4, 80.0, 85.2, and 92.0 degrees F). The subjects were divided into two groups, A (n = 8) and B (n = 6). Thirty minutes of exercise at 40% Vo2 max was performed from 60 to 90 min for group A and 30 to 60 min for group B. Pulmonary function changes, determined throughout exposure, were greatest immediately after exercise in both groups. Few changes occurred before the exercise period. However, the decrease in FVC (826 ml) and FEV1.0 (937 ml) following exercise was more than twice as large as the decrement seen at end exosure (388 and 423 ml, respectively). Measures of maximum expiratory flow (FEF 25-75%, FEF 50% FEF 75%) showed similar reductions. In many cases, reversal of these changes occurred during the remainder of the exposure period. The greatest decrease in FVC occurred when heat and ozone exposures were combined (WBGT = 92.0 degrees F). We conclude that the effects of ozone are most severe immediately after exercise and that heat stress may modify the overall effect of ozone on pulmonary function.

Adult↗