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Biomedical subjects

W C Adams

Publications and source records attributed to W C Adams.

At least 37 records · Page 2Linked to original sources
PubMed1988

Body composition analysis by bioelectrical impedance: effect of skin temperature.

Bioelectrical impedance analysis (BIA) was used to estimate body water and composition under both cool (14.4 degrees C, dry bulb) and warm (35.0 degrees C) ambient conditions in eight healthy adult men. The prediction equation provided with the commercially available instrument (RJL Systems) was used with the BIA measurements to estimate body composition. Skin temperature increased from 24.1 +/- 1.81 degrees C in the cool condition to 33.4 +/- 1.36 degrees C in the warm condition. (Mean increase was 9.3 +/- 1.75 degrees C, t = 15.05, P less than 0.01). The corresponding BIA resistances were 461 +/- 48 omega and 426 +/- 47 omega, respectively. (Mean reduction was 35.0 +/- 9.8 omega, t = 10.13, P less than 0.01). This resulted in a significant increase in predicted total body water (cool 47.4 +/- 5.5 l vs. warm 49.9 +/- 5.6 l, t = 3.88, P less than 0.01). Consequently, predicted fat mass was significantly lower in the warm than in the cool condition (8.8 +/- 3.2 kg vs. 11.0 +/- 3.7 kg; mean difference 2.23 +/- 0.69 kg, t = 9.22, P less than 0.01). These findings indicate that varying skin temperature by altering ambient temperature significantly changes resistance measurements and the estimation of total body water and percent fat by BIA. The observed changes in resistance are consistent with an apparent expansion of conductor volume in the warm environment and a reduction in the cooler condition. In this regard, the temperature-induced change in resistance could be due to alterations in cutaneous blood flow and/or compartmental distribution of body water. Thus, BIA measurements should be taken only under well-standardized ambient conditions.

Adipose Tissue↗
PubMed1987

Effects of NO2 alone and in combination with O3 on young men and women.

Previous studies of 2 h of exposure to NO2 at high urban atmospheric levels (i.e., 0.50-1.0 ppm), utilizing light-to-moderate exercise for up to 1 h have failed to demonstrate significant pulmonary dysfunction in healthy humans. To test the hypothesis that heavy sustained exercise would elicit pulmonary dysfunction on exposure to 0.60 ppm NO2 and/or enhance the effects of exposure to 0.30 ppm O3, 40 aerobically trained young adults (20 males and 20 females) completed 1 h of continuous exercise at work rates eliciting a mean minute ventilation of 70 and 50 l/min for the males and females, respectively. Exposures to filtered air, 0.60 ppm NO2, 0.30 ppm O3, and 0.60 ppm NO2 plus 0.30 ppm O3 were randomly delivered via an obligatory mouthpiece inhalation system. Treatment effects were assessed by standard pulmonary function tests and exercise ventilatory and subjective symptoms response. Two-way analysis of variance with repeated measures and post hoc analyses revealed a statistically significant (P less than 0.05) effect of O3 on forced expiratory parameters, specific airway resistance, exercise ventilatory response, and reported subjective symptoms of respiratory discomfort. In contrast, no significant effect of NO2 was observed nor was there any significant interaction of NO2 and O3 in combination. There were no significant differences between male and female responses to gas mixture treatments. It was concluded that inhalation of 0.60 ppm NO2 for 1 h while engaged in heavy sustained exercise does not elicit effects evidenced by measurement techniques used in this study nor evoke additive effects beyond those induced by 0.30 ppm O3 in healthy young adults.

Adult↗
PubMed1987

Indomethacin pretreatment reduces ozone-induced pulmonary function decrements in human subjects.

We studied whether O3-induced pulmonary function decrements could be inhibited by the prostaglandin synthetase inhibitor, indomethacin, in healthy human subjects. Fourteen college-age males completed six 1-h exposure protocols consisting of no drug, placebo, and indomethacin (Indocin SR 75 mg every 12 h for 5 days) pretreatments, with filtered air and O3 (0.35 ppm) exposures within each pretreatment. Pretreatments were delivered weekly in random order in a double-blind fashion. Ozone and filtered air exposures, separated by 72 h, were delivered in random order in a single-blind fashion. Exposures consisted of 1-h exercise on a bicycle ergometer with work loads set to elicit a mean minute ventilation of 60 L/min. Statistical analysis revealed significant (p less than 0.05) across pretreatment effects for FVC and FEV1, with no drug versus indomethacin and placebo versus indomethacin comparisons being significant. These findings suggest that cyclooxygenase products of arachidonic acid, which are sensitive to indomethacin inhibition, play a prominent role in the development of pulmonary function decrements consequent to acute O3 exposure.

Adult↗
PubMed1987

Effects of porcine relaxins upon uterine hypertrophy and protein metabolism in mice.

Two variant forms of porcine relaxin (B and C) are active in producing relaxation of the guinea pig pubic symphysis and in effecting uterine growth in rats. Only relaxin B, however, is active in the mouse pubic ligament assay. These two hormones were compared in mice for their effects upon uterine growth and incorporation of radioactively labeled proline into soluble protein and collagen in vitro and in vivo. Both relaxin B and relaxin C produced an early (3-hr) elevation in in vitro protein synthesis and a later (6-hr) increase in collagen incorporation of proline at the time when the uterotrophic effect was maximal. In vivo effects of relaxin C on the uterus were in some cases greater than relaxin B in contrast to the complete inactivity of the former upon the pubic ligament of the mouse. These findings suggest a high degree of tissue specificity for relaxin stimulation, a variability in responsiveness among tissues in the same animal, and perhaps a primary role of relaxin in uterine function with pelvic relaxation representing a secondary function which has developed in certain species.

Animals↗
PubMed1986

Hormonal changes during the early development of ovarian cysts in the rat.

The daily administration of human chorionic gonadotropin (hCG) to rats with thiouracil-induced hypothyroidism results in the development of cystic ovaries. This study was undertaken to delineate hormonal changes during the first 48 h of hCG treatment. Groups of euthyroid and hypothyroid rats were injected daily with hCG or saline for up to two days and killed at 0, 12, 24, or 48 h after the initial hCG injection. Sera were analyzed for progesterone (P), testosterone (T), 17 beta-estradiol (E2), and prolactin (Prl) by specific radioimmunoassay (RIA). Serum levels of these hormones were not significantly different in the euthyroid and hypothyroid rats. However, P was significantly elevated at 12, 24, and 48 h in the hypothyroid/hCG rats. T and Prl were significantly elevated at 12 and 48 h in the hypothyroid/hCG rats. T levels were also elevated at 12 and 48 h in the euthyroid rats receiving hCG. In contrast, hCG had no effect on P and Prl levels in the euthyroid rats. E2 levels were undetectable in the euthyroid and hypothyroid rats. The administration of hCG increased E2 in both the euthyroid and hypothyroid rats at 48 h with significantly more E2 detected in the hypothyroid rats. These results show that ovarian steroids and Prl levels increase during the early stages of cyst induction and suggest they may be important in triggering ovarian cyst formation.

Animals↗
PubMed1986

Effects of ozone exposure on four consecutive days on work performance and VO2max.

The effects of 4 consecutive days of 1-h exposure to 0.35 ppm ozone (O3) on maximal O2 uptake (VO2max), performance time, pulmonary function, and subjective symptom responses were studied in eight aerobically trained males. Each subject was first exposed in random order to filtered air (FA) and 0.35 ppm O3 while exercising on a bicycle ergometer for 50 min at a work load eliciting minute ventilation of approximately 60 1/min. A rapidly incremented VO2max test to volitional fatigue was completed within 10 min following each of these exposures, as well as on day 4 of the consecutive daily exposures to O3. Initial exposure to O3 induced the occurrence of subjective symptoms, as well as significant pulmonary function impairment and decrements in maximal exercise performance time (from 253 to 211 s) and VO2max (from 3.85 to 3.62 l/min). Following the fourth consecutive day of exposure to O3, pulmonary function impairment was not significantly different from initial exposure to O3, although subjective symptom severity was significantly reduced. Exercise performance time (239 s) and VO2max (3.79 l/min) on the fourth consecutive daily exposure to O3 were not significantly different from FA values. These data indicate no significant adaptation to initial O3 exposure-induced pulmonary function impairment following four consecutive daily exposures to O3, although reduced subjective symptom severity and enhanced exercise performance time on day 4 suggest an habituation effect. Our results also suggest that O3 adaptation may be a more complex phenomena than identified previously.

Adaptation, Physiological↗
PubMed1986

Reduced exercise time in competitive simulations consequent to low level ozone exposure.

Ten highly trained endurance athletes were studied to determine the effects of exposure to low ozone (O3) concentrations on simulated competitive endurance performance and associated physiological and subjective symptom responses. Each subject was randomly exposed to filtered air (FA), and to 0.12, 0.18, and 0.24 ppm O3 while performing a 1 h competitive simulation protocol on a bicycle ergometer. Endurance performance was evaluated by the number of subjects unable to complete rides (last 30 min at an intense work load of approximately 86% VO2max). All subjects completed the FA exposure, whereas one, five, and seven subjects did not complete the 0.12, 0.18, and 0.24 ppm O3 exposures, respectively. Statistical analysis indicated a significant (P less than 0.05) increase in the inability of subjects to complete the competitive simulations with increasing O3 concentration, including a significant difference between the 0.24 ppm O3 and FA exposure. Significant decreases (P less than 0.05) were also observed following the 0.18 and 0.24 ppm O3 exposures, respectively, in forced vital capacity (-7.8 and -9.9%), and forced expiratory volume in 1 s (-5.8 and -10.5%). No significant O3 effect was observed for exercise respiratory metabolism or ventilatory pattern responses. However, the number of reported subjective symptoms increased significantly following the 0.18 and 0.24 ppm O3 protocols. These data demonstrate significant decrements in simulated competitive endurance performance and in pulmonary function, with accompanying enhanced subjective symptoms, following exposure to low O3 levels commonly observed in numerous metropolitan environments during the summer months.

Adult↗
PubMed1985

Inhibition of postpartum uterine involution in the rat by relaxin.

The possible contribution of relaxin to the support of uterine accommodation during late gestation by retarding tissue lysis was examined using the involuting postpartum uteri of unilaterally pregnant rats. In otherwise intact animals, twice-daily administration of 0.1 mg of relaxin (porcine fraction B) significantly retarded the regression of both gravid and, to a greater extent, nongravid tissue during the first 4 days postpartum, and collagenolysis was similarly delayed. Immediate postpartum ovariectomy had little effect on the uterus, although 5 micrograms estradiol benzoate daily suppressed uterine involution in the gravid tissue to about 50% and was even more effective in the nongravid uterus. Relaxin alone had little effect on the gravid uterus following ovariectomy, but augmented estrogen to the extent that less than half of the tissue and its collagen were lost during 4 days. The effect on nongravid tissue was even more striking in that the combination of estrogen and relaxin prevented any degradation of tissue in general or of collagen. Although we have reported that relaxin can stimulate uterine collagen synthesis as well as uterine growth, the magnitude of its postpartum effect in the presence of estrogen suggests a stabilizing or anticatabolic effect upon the uterus.

Animals↗
PubMed1985

Ozone inhalation effects consequent to continuous exercise in females: comparison to males.

Exposure to ozone (O3) at ambient photochemical smog alert levels has been shown to cause alteration in pulmonary function and exercise response in humans, but there is a paucity of data on females. The initial purpose of the present investigation was to study the effects of O3 inhalation on pulmonary function and selected exercise respiratory metabolism and breathing pattern responses in young adult females. Six female subjects exercised continuously on a bicycle ergometer for 1 h on 10 occasions at one of three intensities, while exposed to 0.0, 0.20, 0.30, or 0.40 ppm O3. Forced expiratory volume and flow rates and residual volume (RV) were measured before and immediately following each protocol. During exercise, expired minute ventilation (VE), respiratory frequency (fR), tidal volume, O2 uptake (VO2), and heart rate (HR) were measured every 10 min. O3 dose-dependent decrements were observed for forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), and forced expiratory flow rate during the middle half of FVC, coupled with an increase in RV and altered exercise ventilatory pattern. There was also an increased VE but no significant O3 effect on VO2 or HR. Comparison of the females' responses to those of a group of young adult males (previously studied) at the same total O3 effective dose (i.e., expressed as the simple product of O3 concentration, VE, and exposure time) revealed significantly greater effects on FVC, FEV1.0, and fR for the females. With VE reduced for females as a function of exercise intensity at the same percent of maximum VO2, these differences were considerably attenuated, although not negated.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Stimulation of rat uterine collagen synthesis by relaxin.

Immature, ovariectomized, estrogen-primed rats respond to the administration of porcine relaxin by an increase in the incorporation of labeled amino acids ([14C]leucine, [14C]phenylalanine, [3H]proline) into uterine proteins in vitro. The maximum response occurs about 12 hr after a single injection of 0.1 mg relaxin in benzopurpurine 4B solution; subsequently, the relaxin effect declines but is still apparent after 24 hr. Smaller, but still significant increases in incorporation rates can be induced by relaxin in the absence of estrogen priming. Uterine collagen synthesis, as indicated by the incorporation of [3H]proline and its conversion to hydroxyproline, appears to be a primary target of the relaxin stimulus, since the effect of relaxin upon proline incorporation into uterine collagen is significantly greater than its effect upon labeling of noncollagen protein.

Animals↗
PubMed1984

Effects of ozone inhalation during exercise in selected patients with heart disease.

Although epidemiologic evidence suggests that patients with heart and lung disease are more vulnerable to the acute toxic effects of photochemical air pollution, no laboratory studies have been reported in patients with coronary heart disease. In the present investigation, six male volunteers, ages 46 to 64 years, with clinically documented coronary heart disease and a well-defined symptomatic angina pectoris threshold, served as subjects. Each patient was exposed on three 40-minute occasions to either filtered air or ozone at concentrations of 0.20 or 0.30 parts per million (ppm), while walking on a treadmill at workloads simulating their regularly prescribed exercise training regimen. Results of standard pulmonary function tests and periodic observations of exercise ventilation, respiratory metabolism, electrocardiographic changes, hemodynamic response, and clinical signs and symptoms were recorded. Analysis of variance revealed that none of the patients' physiologic responses to ozone exposure were statistically significant. Furthermore, neither onset of angina pain or ischemic changes were related to ozone exposure in a dose-dependent fashion. Hence, the patients not only failed to exhibit any unexpected cardiovascular strain while exposed to ozone during exercise, but also evidenced no significant pulmonary function impairment or exercise ventilatory pattern alteration, as has been observed in clinically normal subjects exercising at similar ozone concentration levels. This apparent incongruity may be due to the fact that acute ozone toxicity is more closely related to the total amount of ozone inhaled, which is a function of pulmonary ventilation volume and exposure time, as well as ozone concentration. In the patients with angina, symptom-limited exercise tolerance resulted in a lower total amount of ozone inhaled than that observed to effect ozone toxicity in clinically normal subjects who exercised at greater intensities and for longer durations. Patients with angina appear to be no more susceptible to ozone toxicity than are clinically normal subjects at the effective doses imposed. However, had the patients exercised longer, they might well have evidenced pulmonary function impairment and/or cardiovascular strain. Hence, caution is advised in generalizing these observations to other conditions and patient groups.

Angina Pectoris↗
PubMed1984

Effects of airflow and work load on cardiovascular drift and skin blood flow.

Cardiovascular drift (CVD) can be defined as a progressive increase in heart rate (HR), decreases in stroke volume (SV) and mean arterial pressure (MAP), and a maintained cardiac output (Q) during prolonged exercise. To test the hypothesis that the magnitude of CVD would be related to changes in skin blood flow ( SkBF ), eight healthy, moderately trained males performed 70-min bouts of cycle ergometry in a 2 X 2 assortment of airflows (less than 0.2 and 4.3 m X s-1) and relative work loads (43.4% and 62.2% maximal O2 uptake). Ambient temperature and relative humidity were controlled to mean values of 24.2 +/- 0.8 degrees C and 39.5 +/- 2.4%, respectively. Q, HR, MAP, SkBF , skin and rectal temperatures, and pulmonary gas exchange were measured at 10-min intervals during exercise. Between the 10th and 70th min during exercise at the higher work load with negligible airflow, HR and SkBF increased by 21.6 beats X min-1 and 14.0 ml X 100 ml-1 X min-1, respectively, while SV and MAP decreased by 16.4 ml and 11.3 mmHg. The same work load in the presence of 4.3 m X s-1 airflow resulted in nonsignificant changes of 7.6 beats X min-1, 4.0 ml X (100 ml-1 X min)-1, -2.7 ml, and -1.7 mmHg for HR, SkBF , SV, and MAP. Since nonsignificant changes in HR, SkBF , SV, and MAP were observed at the lower work load in both airflow conditions, the results emphasize that CVD occurs only in conditions which combine high metabolic and thermal circulatory demands.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1984

Combined effects of ozone exposure and ambient heat on exercising females.

Ten aerobically trained young adult females exercised continuously at 66% of maximum O2 uptake for 1 h while exposed orally to filtered air and 0.15 and 0.30 parts per million (ppm) ozone (O3) in both moderate (24 degrees C) and hot (35 degrees C) ambient conditions. Exposure to 0.30 ppm O3 induced significant impairment in forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1.0), and other pulmonary function variables. Exercise respiratory frequency (fR) increased, whereas tidal volume and alveolar volume (VA) decreased with 0.30 ppm O3 exposure. Significant interactions of O3 and ambient heat were obtained for fR and VA, whereas FVC and FEV1.0 displayed a trend toward an O3-temperature interaction. Although expired ventilation increased, the interactions could not be ascribed to a greater O3 effective dose in the 35 degrees C exposures. However, subjective discomfort increased with both O3 and heat exposure such that three subjects ceased exercise prematurely when O3 and ambient heat were combined. We conclude that accentuation of subjective limitations and certain physiological alterations by ambient heat coinciding with photochemical oxidant episodes is likely to result in more severe impairment of exercise performance, although the mechanisms remain unclear.

Adult↗
PubMed1983

Ozone and high ventilation effects on pulmonary function and endurance performance.

Ozone (O3) toxicity is potentiated by exercise-induced expired minute ventilation (VE) for a given exposure, which may also impair endurance performance. Ten healthy, well-trained long-distance runners were exposed on six occasions for 1 h to O3 concentrations of 0, 0.20, or 0.35 parts per million (ppm), during exercise simulating either training or competition, with mean VE = 77.5 1 X min -1. Standard pulmonary function tests, subjective symptoms, and periodic observations of exercise ventilatory response and respiratory metabolism were obtained. Statistical analyses revealed no significant exercise mode effect for pulmonary function, but a significant O3 effect for forced vital capacity and expiratory volume at 1 s was observed. Altered exercise ventilatory pattern response was noted, but there was no significant O3 effect on exercise oxygen uptake, heart rate, VE, or alveolar ventilation. Subjective symptoms increased with O3 concentration. Statistically significant pulmonary function impairment observed at 0.20 ppm O3 suggests that endurance athletes may be more susceptible to the effects of a given O3 concentration than normal young adult males as a result of sustained high mean VE incurred during training and competition. Three subjects were unable to complete both the training and competitive simulations at 0.35 ppm O3. Performance decrements appeared to be the result of physiologically induced respiratory discomfort rather than decrements in pulmonary gas exchange and/or oxygen transport and delivery.

Adult↗
PubMed1983

Resting blood flow in the paretic and nonparetic lower legs of hemiplegic persons: relation to local skin temperature.

It is commonly observed in patients with established hemiplegia following cerebrovascular accidents (CVA), that the skin temperature (Ts) of the leg and foot is notably cooler on the affected side of the body; the relationship to cutaneous blood flow, however, has not previously been investigated. In the present study, observations of foot and calf blood flow via venous occlusion plethysmography in water were made in six patients with hemiplegia of 5-13 months duration, both at observed Ts and at standard temperature (ST). Similar measurements were obtained on six age-matched control subjects. The patients' mean Ts values for the foot and calf were significantly lower on the affected side, while those for the nonaffected side were not significantly different from control group values. At non-equivalent water temperatures (Tw) blood flows in the patients' affected feet were lower than those on the nonaffected side, but at the ST they were similar. Further, under these conditions, the flows in both feet were lower than in control subjects. Flows in the patients' affected calves were not significantly reduced at non-equivalent TW; at the ST they did not differ significantly from those of the controls. These observations suggest that, in patients who have suffered a stroke, the reduction of TS of the affected limb is associated with reduced limb blood flow, which cannot be attributed to changes in limb tissue composition. Since the reduced limb blood flow on the affected side is more marked in the foot, it is likely to be due to reduction of blood flow in the skin. In addition, the reduction of flow in the foot of the nonaffected leg suggests a more generalized change of skin circulation in these patients.

Adult↗