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Biomedical subjects

W C Adams

Publications and source records attributed to W C Adams.

At least 55 records · Page 3Linked to original sources
PubMed1981

Detection of ozone toxicity during continuous exercise via the effective dose concept.

In evaluating O3 toxicity in humans, the effective dose, expressed as the simple product of concentration, exposure duration and ventilation volume (VE), has been applied only to resting or intermittent exercise (IE) exposures. In the present study, we examined the validity of effective dose in predicting pulmonary function impairment when effective dose was determined both as a simple product and as a weighted function via multiple regression. Eight trained male subjects (ages 22-46) completed 18 protocols, including exposures (via mouthpiece) to filtered air and three levels of O3 concentration (0.20, 0.30, and 0.40 ppm), while exercising continuously for durations ranging from 30 to 80 min. The O3 effective dose was significantly related to pulmonary function impairment and exercise ventilatory pattern alteration. Multiple regression analysis, however, substantiated the predominant importance of O3 concentration, with the threshold for O3 toxicity during exercise at a moderately heavy work load [approximately 65% maximum O2 uptake (VO2 max)] shown to be between 0.20 and 0.30 ppm. Although considerable individual variability in O3 toxicity response was noted, group mean responses in our continuous exercise mouthpiece exposures were similar to those previously observed with IE chamber exposures. Thus while the effective dose concept has notable deficiencies in predicting the individual degree of O3 toxicity, it remains a useful approach and warrants further investigation.

Adult↗
PubMed1981

Relationship of polycystic ovary induction to prolactin secretion: prevention of cyst formation by bromocriptine in the rat.

PRL levels were measured over 30 days of cyst induction in the rat. Polycystic ovaries (PCO) were induced by dietary incorporation of thiouracil (Thio) for 30 days and injection of 10 IU hCG sc for the last 20 days of the experimental period. Animals were killed at specific intervals 24 hours after the last injection. Ovaries and thyroids were removed and weighed. Sera were analyzed for PRL by RIA. PRL levels increased in animals receiving Thio plus hCG by day 30 compared to animals receiving Thio alone. The increase in PRL in the Thio, hCG-stimulated group coincides with formation of follicular cysts. Administration of bromocriptine (1 mg/day) concurrent with hCG during the last 20 days of Thio-feeding significantly suppressed ovarian weight gain and PCO formation. Serum PRL levels in bromocriptine-treated rats were significantly reduced compared to the PCO group yet were also significantly greater than all control groups at day 30. These findings suggest that PRL is important to the etiology of ovarian cysts in the rat.

Animals↗
PubMed1980

Lipid involvement in oleoyl CoA desaturase activity of Fusarium oxysporum microsomes.

Desaturation of oleoyl CoA by the microsomal fraction of Fusarium oxysporum hyphal cells required O2, NADPH, MgCl2, and the addition of either bovine serum albumin or the 105 000g supernatant fraction. In the absence of reduced nucleotide, [14C]oleoyl CoA was rapidly incorporated into phospholipid and triacylglycerol and hydrolyzed to free fatty acids. After addition of NADPH, oleate was desaturated at the normal rate. Analysis of the distribution of [14C]oleate and [14C]linoleate between different lipid classes revealed that phosphatidylcholine and phosphatidylethanolamine were labeled with [14C]linoleate before any other lipid class. These results are consistent with oleoyl phospholipid being a direct intermediate in the desaturation of oleoyl CoA. The preference of the oleoyl-desaturase for NADPH, the relatively high pH optimum of 8.2, and the sensitivity to thenoyltrifluoroacetone inhibition suggest that some components of the microsomal electron-transport chain are common to both the oleoyl desaturase and stearoyl CoA desaturase systems in this fungus.

Fatty Acid Desaturases↗
PubMed1979

Effects of oxone inhalation on work performance and VO2 max.

Ozone (O3) at near ambient smog alert levels has previously been shown to cause alterations in pulmonary function and exercise response in humans. The present study was designed to investigate the effects of O3 administered during graded bicycle exercise to volitional fatigue on work performance and maximal oxygen uptake (VO2max). Nine subjects performed three tests each while breathing either 0.00, 0.15, or 0.30 ppm O3. Forced vital capacity, residual volume, maximal midexpiratory flow rate, and forced expiratory volume in 1 s were assessed before, immediately after, and 4 h after exercise. O3 exposure resulted in no significant effect on maximal work rate, anaerobic threshold, or any pulmonary function parameter. However, maximal expired minute ventilation was decreased (P less than 0.05) in a dose dependent fashion. Thus, exercise ventilation during maximal work was a more sensitive indicator of the effects of O2 exposure than were standard pulmonary function tests. Although subjective symptoms of discomfort were reported more frequently with increased O2 level, it was concluded that exposure of healthy young men to as much as 0.30 ppm O2 for no more than 30 min of progressively incremented exercise to volitional fatigue, is insufficient to cause a significant decrease in work capacity or V02 max.

Adult↗
PubMed1979

Temperature changes during exercise measured by thermography.

The present study explores the dynamic changes of surface temperatures associated with peripheral vascular shifts during and following hand gripping, one-legged ergometric, and running exercise. An AGA 680 thermovision system, incorporating a Bolex 16-mm camera and displaying 10-colored isotherms on a slave monitor, generated synchronous infrared (IR) movies at 16 frame/s. Incremental increases in surface skin temperatures (Ts) were observed while gripping at 20, 50, and 80% of maximum with a peak rise of 1.7 degrees C. Thermographic recorded Ts changes during dynamic one-legged exercise were higher in the exercising leg than the resting leg. Surface temperatures dropped in both limbs following exercise. The advantages of the use of thermography during transient thermal states, as produced by dynamic exercise, is supported by comparative Ts data taken from thermograms and thermistors.

Hand↗
PubMed1975

Thermoregulation during marathon running in cool, moderate, and hot environments.

A well-trained subject, age 38, ran continously for periods ranging from 60 to 165 min on a motor-driven treadmill at 255.7 m/min while confronted with an airflow equivalent to running speed in cool, moderate, and hot environments. After a period of intensive heat acclimatization, treadmill runs were repeated in the moderate and hot conditions. Measurements were also obtained outdoors in a competitive marathon race. Sweat rate (SR) and mean skin temperature (Ts) were linearly related to Tdb. Acclimatization did not alter VO2max or metabolic rate during the treadmill runs, but heart rat (HR),rectal temperature (Tre), and Ts were lower, SR was higher, and maximal run duration longer in the hot environment, postacclimatization. Maximum runs in the hot environment were terminated by a spiralling increase in Tre to hyperthermic levels, due largely to a marked reduction in cutaneous blood flow, probably reflecting cardiovascular overload from the combined muscular and thermoregulatory blood flow demands, coupled with the effects of progressive dehydration. Utilizing partitional calorimetry and the subject's metabolic heat production, two examples of limiting environmental conditions for his marathon running speed were given.

Acclimatization↗