Biomedical subjects

C C Cline

Publications and source records attributed to C C Cline.

5 recordsLinked to original sources

PubMed1999

A chest wall restrictor to study effects on pulmonary function and exercise. 1. Development and validation.

Chest wall-restrictive loading reduces a person's ability to expand the chest wall during inhalation and results in decrements in lung capacities, resting pulmonary function, and ultimately, exercise performance. Chest wall restriction is observed in some forms of skeletal and pulmonary diseases (e.g., scoliosis) as well as in occupational situations (e.g., bulletproof vests). We have designed a constant-pressure chest wall-restrictive device that provides a quantifiable and reproducible load on the chest. This paper describes the device and the initial pulmonary function tests conducted. Ten subjects participated in this study. Subjects wore the restrictive device while performing pulmonary function tests at four externally added restrictive loads on three separate occasions. A two-way repeated-measures multivariate analysis of variance revealed significant decreases in forced expiratory vital capacity (FVC) and forced expiratory volume in 1 s (FEV1.0) at each load while the ratio of FEV1.0 to FVC (FEV1.0%) was maintained. No significant differences in any variable were found across time or between the seated and standing position. These results indicate that this chest wall-restrictive device provides a quantifiable added inspiratory load in the breathing cycle that results in reproducible decrements in pulmonary function representative of those seen in some restrictive pulmonary disease and occupational situations.

Adult↗

PubMed1997

Effect of oxidant challenge on contractile function of the aging rat diaphragm.

Although controversial, growing evidence indicates that reactive oxygen species (ROS) alter contractions of skeletal muscle, including the diaphragm. However, the impact of ROS on contractility of the aging diaphragm is unknown. The xanthine oxidase (0.01 U/ml) system was used as an ROS generator, imposing an oxidant challenge. Contractile function [twitch tension; twitch time to peak tension; twitch one-half relaxation time; tension at 10 and 20 Hz; maximal tetanic tension (Po) at 100 Hz] of costal diaphragm fiber bundles from young (4 mo) and old (25 mo) Fischer 344 rats was examined in vitro before and after treatment with control Krebs solution [young control (YC) and old control (OC)], or with xanthine oxidase (XO; 0.01 U/ml) plus hypoxanthine (0.29 mg/ml) substrate [young XO treated (YXO) and old XO treated (OXO)]. Contractile function of fiber bundles was reassessed after oxidant challenge in an unfatigued state (Post-u) or 10 min after a fatiguing stimulation protocol (Post-f). Oxidant challenge in the unfatigued fiber bundles increased twitch tension and tension at 10 and 20 Hz in YXO, but not OXO, without increasing Po. Conversely, XO significantly depressed fatigued diaphragm twitch and low-frequency tension in both OXO and YXO, compared with controls. Po was depressed Post-f in OXO but not YXO. Oxidant challenge also increased twitch one-half relaxation time of the fatigued diaphragm in both age groups. Furthermore, fiber bundles from old rats suffered greater fatigue during the stimulation protocol. We conclude that the response to oxidant challenge and increased contractile demand is impaired in the aging diaphragm.

Aging↗

PubMed1997

Effect of oxidative stress and acidosis on diaphragm contractile function.

Acidosis during exercise has long been associated with skeletal muscle fatigue. Recent evidence also has linked reactive oxygen species (ROS) with fatigue in skeletal muscle, including the diaphragm. We hypothesized that acidosis (designed to mimic blood pH during maximal exercise) would worsen ROS-induced depression of diaphragm contractility. The xanthine oxidase (XO) reaction in solution (0.01 U/ml) allows direct assessment of the effects of oxidant stress by ROS. Costal diaphragm fiber bundles from 24 Sprague-Dawley rats (200-250 g) were divided into four treatment groups: 1) pH 7.4, no XO (H); 2) pH 7.4 + XO (HXO); 3) pH 7.0, no XO (L); and 4) pH 7.0 + XO (LXO). Baseline twitch mechanics and force-frequency relationships (Pre) were determined in control Krebs solution (pH 7.4, no XO) before treatment. Treatment solutions were introduced, and the diaphragm underwent 2 min of contractions at 25 Hz (250 ms) at a rate of 1/s. After 10 min of recovery, the control solution was reintroduced into the bath and postcontractile function (Post) was measured. Significant reductions in twitch tension and low-frequency tetanic tension were greater in HXO and LXO compared with H, without an effect on maximal tetanic tension. One-half relaxation time was prolonged only by the combination of acidosis and oxidative stress. Addition of superoxide dismutase (50 U/ml) worsened and catalase (1,800 U/ml) attenuated XO-induced depression of diaphragm contractility. We concluded that XO induced a reduction of low-frequency tension in the fatigued diaphragm, which was mediated directly or indirectly through hydrogen peroxide and was exacerbated to a modest extent with acidosis.

Acidosis↗

PubMed1995

Effects of inspired O2 and CO2 on ventilatory responses to LBNP-release and acute head-down tilt.

Increases in blood flow and CO2 return to the heart and lungs at the onset of exercise have been proposed to initiate reflexive feedback which increases ventilation (VE), via mechanoreceptors in the heart and/or intrapulmonary CO2 flow receptors. Both lower body negative pressure (-40 mm Hg) release (LBNP-release) and acute head-down (-30 degrees) tilt (TILT) provide physiological models to focus upon the effects of increased venous return and CO2 flow on VE, without the confounding influence of limb afferents or the descending efferents associated with central command. We examined the ventilatory responses to LBNP-release and TILT while inhaling one of four gas mixtures: a) room air (R); b) 95% O2 (O); c) 95% O2, 1.25% CO2 (LC); and d) 95% O2, 2.25% CO2 (HC). Breath-by-breath measurements for VE end-tidal CO2 (PETCO2), tidal volume (VT), and breathing frequency (fB) were taken. VE and VT for HC were significantly higher (p < 0.05) than those for R, O, and LC throughout the test session, while fB and PETCO2 were not significantly different among the gas treatments. VE increased (p < 0.05) above resting baseline with LBNP-release and TILT for R, O, LC, and HC primarily through an elevation of fB. Further, the maximal change in VE following LBNP-release or TILT were not different among inhaled gas mixtures. However, area under the VE curve following LBNP-release and TILT was higher for HC compared to the other gas mixtures. We conclude that these results are inconsistent with the theory that carotid bodies are essential in driving VE with these models.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1992

A comparison between two forms of aerobic dance and treadmill running.

Aerobic dance has been reported to result in a disproportionately higher heart rate than running at a similar percent of VO2max. It has been suggested that the extensive use of the arms overhead during aerobic dance results in an increase in sympathetic outflow thereby disproportionately increasing the heart rate. To compare the hemodynamic and sympathetic nervous system activity responses during aerobic dance and treadmill running, nine healthy females exercised at approximately 50% of their VO2max during each of the following three exercise trials: aerobic dance where the arms were used extensively overhead (ABOVE), aerobic dance where the arms were kept below the shoulders (BELOW), and treadmill running (TR). Mean heart rate values during the ABOVE, BELOW, and TR trials were 136 beats.min-1 for all three trials. Mean VO2 values during the ABOVE, BELOW, and TR trials were 1.48, 1.51, and 1.47 l.min-1, respectively, and were not significantly different. Mean cardiac output for the ABOVE, BELOW, and TR trials were 13.5, 14.0, and 13.0 1. min-1, respectively, and were not significantly different. Postexercise blood lactate and norepinephrine values were not significantly different among the three trials. These results suggest a similar relationship between heart rate and VO2 during low intensity aerobic dance and running and do not support the contention that the use of the arms overhead during aerobic dance exercise elicits a disproportionately greater increase in heart rate as compared with running. Additionally these results demonstrate similar cardiovascular and sympathetic nervous system responses between aerobic dance exercise and running.

Adult↗