Biomedical subjects

P C Weiser

Publications and source records attributed to P C Weiser.

At least 19 recordsLinked to original sources

PubMed2006

Gender differences in the progression of metabolic responses during incremental exercise.

AIM: The present investigation was undertaken to elucidate the differences in the progression of metabolic responses during incremental exercise between men and women of similar maximal aerobic capacity. METHODS: Twenty males and 20 females served as subjects for the study. Each subject was randomly assigned to perform a graded exercise test on either a cycle ergometer or a treadmill. Of the 20 subjects within each gender, 10 were tested on the cycle ergometer, whereas the other half was tested on the treadmill. During each test, absolute VO2, relative VO2, and HR were recorded during the last 15 seconds of every minute throughout the test. These variables were then plotted separately as a function of work rate so that a best-fit linear regression equation was generated for each of the three plots. RESULTS: Under the cycle condition, we found no difference in slope of increment in absolute VO2 between genders. However, the slope of increment in relative VO2 and HR was greater (P<0.05) in women than men. A negative correlation (r=-0.858, P<0.05) was found between body mass and slope of increment in relative VO2 in men and women combined. Under the treadmill condition, the slope for absolute VO2 were greater (P<0.05) in men than women. However, in terms of relative VO2 and HR, no between-gender differences were observed in the slope of increment. A positive correlation (r=0.769, P<0.05) was found between body mass and slope of increment in absolute VO2 in men and women combined. CONCLUSIONS: These results indicate that the progression of metabolic responses during incremental exercise differs between men and women despite a similar fitness. These gender differences may be further attributed to body mass that seems to play a distinctive role when the incremental exercise is conducted on a cycle ergometer and treadmill.

Adult↗

PubMed1998

Expression and localization of epithelial sodium channel in mammalian urinary bladder.

The mammalian urinary bladder exhibits transepithelial Na+ absorption that contributes to Na+ gradients established by the kidney. Electrophysiological studies have demonstrated that electrogenic Na+ absorption across the urinary bladder is mediated in part by amiloride-sensitive Na+ channels situated within the apical membrane of the bladder epithelium. We have used a combination of in situ hybridization, Northern blot analysis, and immunocytochemistry to examine whether the recently cloned epithelial Na+ channel (ENaC) is expressed in the rat urinary bladder. In situ hybridization and Northern blot analyses indicate that alpha-, beta-, and gamma-rat ENaC (rENaC) are expressed in rat urinary bladder epithelial cells. Quantitation of the levels of alpha-, beta-, and gamma-rENaC mRNA expression in rat urinary bladder, relative to beta-actin mRNA expression, indicates that, although comparable levels of alpha- and beta-rENaC subunits are expressed in the urinary bladder of rats maintained on standard chow, the level of gamma-rENaC mRNA expression is 5- to 10-fold lower than alpha- or beta-rENaC mRNA. Immunocytochemistry, using an antibody directed against alpha-rENaC, revealed that ENaCs are predominantly localized to the luminal membrane of the bladder epithelium. Together, these data demonstrate that ENaC is expressed in the mammalian urinary bladder and suggest that amiloride-sensitive Na+ transport across the apical membrane of the mammalian urinary bladder epithelium is mediated primarily by ENaC.

Animals↗

PubMed1983

Effects of particulate air pollution on asthmatics.

Twenty-four asthmatic subjects in Denver were followed from January through March 1979, a three-month period in which Denver air pollution levels are generally high and variable. Dichotomous, virtual impactor samplers provided daily measurements (micrograms/m3) of inhaled particulate matter (total mass, sulfates, and nitrates) for coarse (2.5--15 micrograms in aerodynamic diameter) and fine fractions (less than 2.5 micrometers). Carbon monoxide, sulfur dioxide, ozone, temperature, and barometric pressure were also measured. Twice daily measurements of each subject's peak expiratory flow rates, use of as-needed aerosolized bronchodilators, and report of airways obstruction symptoms characteristic of asthma were tested for relationships to air pollutants using a random effects model across subjects. During the time actually observed, there were very few days in which high levels of suspended particulates were recorded. Of the environmental variables studied, only fine nitrates were associated with increased symptom reports and increased aerosolized bronchodilator usage.

Adult↗

PubMed1981

Atropine and exercise-induced bronchoconstriction.

Six asthmatic children were studied to determine whether supplemental, parenteral atropine would increase the effects of bronchodilation and protection against exercise-induced bronchoconstriction after maximal effects had been achieved by inhalation. First, we determined the amount of inhaled atropine sulfate that would give maximal bronchodilation for each patient at rest. This quantity of atropine was designated as "A." Then all subjects exercised for five sessions with the following pre-exercise treatments in a random order: (a) inhaled distilled water plus intramuscular (IM) saline solution; (b) inhaled A dose of atropine plus IM saline solution; (c) inhaled distilled water plus 0.35 mg IM atropine; (d) inhaled A dose of atropine plus 0.35 mg IM atropine; and (e) inhaled double the A dose plus IM saline solution. The results showed that the combination of inhaled and IM atropine had the greatest bronchodilation effect and the greatest protection against exercise-induced bronchoconstriction. Atropine inhalation alone (A dose) or IM injection (0.35 mg) was not as effective in bronchodilation or in alleviation of exercise-induced bronchoconstriction. Doubling the dose of inhalation (2A) did not increase the effects of the A dose. These results support the hypothesis that inhaled atropine does not reach all the airways where cholinergic receptors are present.

Adolescent↗

PubMed1981

Calibration and stability of Standard and Mini-Wright peak flow meters.

Periodic checks of peak flow meter (PFM) stability is essential to ensure meaningful application even when the PFMs are only used to measure the relative changes in patient peak flow rate. Calibration of PFMs becomes necessary, however, when peak flow readings are to be interpreted precisely. Techniques and flow systems which offer ease and accuracy in calibrating and/or checking PFMs were tested on Standard Wright and Mini-Wright PFMs. Individual Wright PFMs were found to be stable over a six-month testing period. The PFM readings varied from actual flow, however, and the variation from actual flow was greatest among the Mini-Wright PFMs.

Forced Expiratory Flow Rates↗

PubMed1980

Effectiveness of a portable face mask in attenuating exercise-induced asthma.

Recent investigations have demonstrated that exercise-induced asthma (EIA) can be prevented by inspiration of warm, fully humidified air during exercise. We evaluated the success of a surgical face mask, used to retain warm, humidified, expired air, in preventing EIA in ten asthmatic children. subjects underwent six minutes of exercise on a treadmill during two sessions, in one session breathing room air and in another wearing a mask covering the nose and mouth. On the control day, average group forced expiratory volume in 1 s (FEV1) and maximal midexpiratory flow rate (MMEF) decreased from the preexercise baseline value to 66% and 47% of baseline, respectively, at six minutes; on the mask day, FEV1 and MMEF were 91% and 82% of the baseline values (increased in all subjects). A simple face mask may be an inexpensive, nonpharmacologic alternative for alleviation of EIA.

Adolescent↗

PubMed1980

Supplemental dietary carnitine and lipid metabolism in exercising rats.

Rats were physically trained by treadmill running and fed normal, high fat, or identical diets supplemented with 1.0% D,L-carnitine. Fatty acid oxidation, stimulated by exercise and/or by a high fat diet was studied to determine if it might be further augmented by supplemental dietary carnitine. Fatty acid oxidation in vitro or in vivo was unaffected by carnitine feeding. Carnitine feeding was associated with an increase in heart and muscle palmitylcarnitine acyltransferase activity and reduced serum cholesterol in trained rats fed the high fat diet. Under the conditions of this study, supplemental dietary carnitine did not greatly alter glyceride synthesis, lipolysis, or fatty acid oxidation, which indirectly indicates that the increased demands for fatty acid oxidation resulting from exercise or from fat feeding are adequately supported by endogenous levels of carnitine.

Animals↗

PubMed1979

Airway cooling. Stimulus for exercise-induced asthma.

Five patients were studied using a randomly assigned sequence of four inspired-air conditions during strenuous treadmill exercise for 10 min. The four inspired-air conditions were: (1) Cool, dry room air (CDA) at 23 degrees C with 3 mg of water and 7.3 cal of heat content/l, (2) over-saturated air (OSA) at room temperature containing 43 mg water and 16.3 cal/l, (3) hot, dry air (HDA) at 120 degrees C having 3 mg water and 24.4 cal/l, and (4) warm, humidified air (WHA) at 37 degrees C with 43 mg water and 34.7 cal/l. Using inspired-air CDA and OSA, all patients manifested exercise-induced asthma (EIA) while forced expiratory volume in 1 sec (FEV1) and maximal mid-expiratory flow (MMEF) decreased to an average of 81% and 63% of the baseline when breathing CDA and to 83% and 71% of the baseline when breathing OSA. With WHA, EIA was clearly prevented while the post-exercise FEV1 and MMEF were 101% and 103% of baseline, respectively. With HDA, the post-exercise FEV1 and MMEF were 95% and 86% of baseline, respectively. Analysis of variance revealed that the post-exercise pulmonary function changes had resulted solely from respiratory heat loss and not from water loss or from interaction of heat and water losses. These results indicate that exercise-induced asthma is associated with airway cooling incurred during exercise rather than airway dehydration.

Adolescent↗

PubMed1975