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Biomedical subjects

M O'Toole

Publications and source records attributed to M O'Toole.

At least 37 records · Page 2Linked to original sources
PubMed1997

A randomized trial comparing aerobic exercise and resistance exercise with a health education program in older adults with knee osteoarthritis. The Fitness Arthritis and Seniors Trial (FAST).

OBJECTIVE: To determine the effects of structured exercise programs on self-reported disability in older adults with knee osteoarthritis. SETTING AND DESIGN: A randomized, single-blind clinical trial lasting 18 months conducted at 2 academic medical centers. PARTICIPANTS: A total of 439 community-dwelling adults, aged 60 years or older, with radiographically evident knee osteoarthritis, pain, and self-reported physical disability. INTERVENTIONS: An aerobic exercise program, a resistance exercise program, and a health education program. MAIN OUTCOME MEASURES: The primary outcome was self-reported disability score (range, 1-5). The secondary outcomes were knee pain score (range, 1-6), performance measures of physical function, x-ray score, aerobic capacity, and knee muscle strength. RESULTS: A total of 365 (83%) participants completed the trial. Overall compliance with the exercise prescription was 68% in the aerobic training group and 70% in the resistance training group. Postrandomization, participants in the aerobic exercise group had a 10% lower adjusted mean (+/- SE) score on the physical disability questionnaire (1.71 +/- 0.03 vs 1.90 +/- 0.04 units; P<.001), a 12% lower score on the knee pain questionnaire (2.1 +/- 0.05 vs 2.4 +/- 0.05 units; P=.001), and performed better (mean [+/- SE]) on the 6-minute walk test (1507 +/- 16 vs 1349 +/- 16 ft; P<.001), mean (+/-SE) time to climb and descend stairs (12.7 +/- 0.4 vs 13.9 +/- 0.4 seconds; P=.05), time to lift and carry 10 pounds (9.1 +/- 0.2 vs 10.0 +/- 0.1 seconds; P<.001), and mean (+/-SE) time to get in and out of a car (8.7 +/- 0.3 vs 10.6 +/- 0.3 seconds; P<.001) than the health education group. The resistance exercise group had an 8% lower score on the physical disability questionnaire (1.74 +/- 0.04 vs 1.90 +/- 0.03 units; P=.003), 8% lower pain score (2.2 +/- 0.06 vs 2.4 +/- 0.05 units; P=.02), greater distance on the 6-minute walk (1406 +/- 17 vs 1349 +/- 16 ft; P=.02), faster times on the lifting and carrying task (9.3 +/- 0.1 vs 10.0 +/- 0.16 seconds; P=.001), and the car task (9.0 +/- 0.3 vs 10.6 +/- 0.3 seconds; P=.003) than the health education group. There were no differences in x-ray scores between either exercise group and the health education group. CONCLUSIONS: Older disabled persons with osteoarthritis of the knee had modest improvements in measures of disability, physical performance, and pain from participating in either an aerobic or a resistance exercise program. These data suggest that exercise should be prescribed as part of the treatment for knee osteoarthritis.

Activities of Daily Living↗
PubMed1996

Effects of a single bout of ultraendurance exercise on lipid levels and susceptibility of lipids to peroxidation in triathletes.

OBJECTIVE: To determine the effects of a single bout of ultraendurance exercise, as a model for physiologic stress, on lipid and lipoprotein levels, and oxidative susceptibility of lipids in highly trained athletes. DESIGN: Observational trial. POPULATION AND SETTING: Thirty-nine volunteer subjects (26 mean, 13 women; mean age, 38 +/- 10 years) who competed in and completed the 1994 Hawaii Ironman World Championship Triathlon consisting of a consecutive 3.9-km (2.4-mi) swim, 180.2-km (112-mi) bike ride, and a 42.2-km (26.2-mi) run. Subjects answered questionnaires and had blood samples obtained 2 days prior to and within 15 minutes of completion of the triathlon. MAIN OUTCOME MEASURES: Prerace vs postrace changes in lipid and lipoprotein levels, and susceptibility of lipids to peroxidation. RESULTS: The mean duration of exercise was 753 +/- 128 minutes. With exercise, plasma volume-corrected levels of triglycerides decreased 39% from 1.58 +/- 0.83 to 0.97 +/- 0.68 mmol/L (139.6 +/- 73.6 to 85.8 +/- 60.5 mg/dL) (P < .001). Levels of total cholesterol decreased 9% from 4.94 +/- 0.88 to 4.50 +/- 0.79 mmol/L (190.8 +/- 33.8 to 173.8 +/- 30.6 mg/dL) (P < .001), low-density lipoprotein cholesterol decreased 11% from 2.59 +/- 0.77 to 2.30 +/- 0.86 mmol/L (100.1 +/- 29.9 to 88.7 +/- 33.3 mg/dL) (P = .02), and apolipoprotein B decreased 10% from 0.91 +/- 0.20 to 0.82 +/- 0.18 g/L (90.7 +/- 20.0 to 82.0 +/- 17.9 mg/dL) (P < .001). High-density lipoprotein cholesterol and apolipoprotein A-I increased with exercise but not significantly. The susceptibility of lipids to peroxidation decreased significantly (4.51 +/- 1.91 micromol/L, preexercise, vs 2.42 +/- 2.27 micromol/L, postexercise, P < .001), an effect that was not related to antioxidant use or levels of vitamins A, C, or E. Serum iron, a potential pro-oxidant, also decreased by 45% with exercise from 15.75 +/- 5.55 to 8.59 +/- 4.30 micromol/L (88 +/- 31 to 48 +/- 24 micrograms/dL) (P < .001), an effect that was weakly correlated with changes in lipid peroxidation (P = .05). CONCLUSIONS: These data suggest that a single bout of prolonged exercise can reduce lipid and lipoprotein risk factors for developing cardiovascular disease. Moreover, susceptibility of lipids to peroxidation is reduced by exercise, thereby adding to the benefits of physical activity. This effect appears to be independent of antioxidant supplement use and may be mediated by induction of endogenous antioxidants. These observations may explain in part the reduced risk of developing vascular and other diseases in individuals who are physically active.

Adult↗
PubMed1993

Color flow mapping and Doppler velocimetry in the diagnosis and management of a placental chorioangioma associated with nonimmune fetal hydrops.

BACKGROUND: Placental chorioangiomas are the most common tumors of the placenta, occurring in 1% of all pregnancies. With the increasing use of ultrasound, prenatal recognition of these tumors is becoming more common. CASE: A 36-year-old woman presented at 28 weeks' gestation with an intrauterine mass suggested by color flow and Doppler studies to be a vascular tumor. Because of the association of these findings to nonimmune fetal hydrops, management included umbilical blood sampling and intravascular transfusion for fetal anemia. This intervention temporarily corrected the hydrops and significantly prolonged the pregnancy. CONCLUSION: Color flow mapping and Doppler flow studies of intrauterine tumors associated with fetal nonimmune hydrops can be helpful in both diagnosis and management.

Adult↗
PubMed1992

Aging and physical activity determine cardiac structure and function in the older athlete.

To evaluate the effects of age and physical activity on cardiac structure and function, 45 ultra-endurance athletes were compared with 24 sedentary control subjects. Two-dimensionally guided M-mode echocardiograms and pulsed Doppler studies of left ventricular inflow velocity were obtained. Both older and younger athletes differed from age-similar sedentary control subjects in having lower heart rates (56 vs. 72 beats/min, younger; 53 vs. 74 beats/min, older), larger left ventricular cavities at end diastole (5.4 vs. 4.9 cm younger; 5.4 vs. 4.9 cm older), and higher ratios of early to atrial inflow velocities (2.14 vs. 1.37, younger; 1.32 vs. 0.83, older; all P less than 0.05). Older athletes differed from younger athletes in having higher systolic and diastolic blood pressures (131/79 vs. 122/71 mmHg), greater posterior wall thickness (1.1 vs. 0.9 cm), lower rapid filling velocity (52 vs. 70 cm/s), higher atrial systolic velocity (41 vs. 34 cm/s), and lower early-to-atrial inflow velocity ratios (1.32 vs. 2.14, all P less than 0.05). Thus the aging heart manifests structural and functional changes in response to physical activity that are similar but not identical to those seen in younger subjects. The expected pattern of cardiac alterations normally seen in response to age is modified in the older athlete, suggesting that exercise training, as well as aging, is an effective stimulus in shaping left ventricular structure and function in the older heart.

Adult↗
PubMed1991

A phase I clinical trial with gadodiamide injection, a nonionic magnetic resonance imaging enhancement agent.

Twenty adult male volunteers were studied in an unblinded, ascending-dose study to evaluate the safety, tolerance, and pharmacokinetics of intravenously administered nonionic gadodiamide injection. Dosages administered were 0.05, 0.1, 0.2, and 0.3 mmol/kg. Subjects were monitored from 36 hours before, through 72 hours after administration. There were no clinically relevant changes in vital signs or electrocardiograms. No clinically significant changes occurred in blood or urine laboratory parameters, although a tendency for minor, transient elevations in serum iron levels 8 to 48 hours after administration was noted. These changes were not dose-related. Nine of 20 subjects reported at least one adverse event; all events were transient and of mild intensity, the most common being dizziness/lightheadedness and perversion of taste or smell. One subject reported discomfort consisting of mild stinging at the injection site during administration. Gadodiamide was excreted unmetabolized in the urine with greater than 95% recovery at 72 hours after administration. The serum elimination half-life was approximately 70 minutes.

Adult↗
PubMed1990

Effect of lactic acidosis on canine hemodynamics and left ventricular function.

Hypoperfusion states cause lactic acidosis, and the acidemia further reduces the inadequate cardiac output. Conceivably, the adverse effect of lactic acidemia on cardiac output is due to depressed contractility demonstrated in isolated myocardium. Alternatively, factors governing venous return cause a relative hypovolemic state and/or acidemic pulmonary vasoconstriction-induced right ventricular dysfunction. We reasoned that examination of left ventricular pressure-volume relationships at end systole and end diastole would determine which of these potential mechanisms accounted for reduced cardiac output during progressive lactic acidosis in anesthetized, mechanically ventilated dogs. Left ventricular (LV) volume was estimated from two pairs of epicardial ultrasonic crystals placed in the anterior-posterior and longitudinal planes, and LV pressure was obtained rom a catheter-tipped transducer. During progressive acidemia induced by a continuous intravenous infusion of 0.5 N lactic acid, cardiac output, stroke volume, and mean systemic arterial pressure fell significantly while mean pulmonary artery pressure and right atrial pressure increased significantly. These variables did not change with time in control (no-acid infusion) dogs. Lactic acidemia caused a 40% reduction in stroke volume, which could be attributed to depressed LV contractility, characterized by a decrease in maximum dP/dt as well as a fall in slope (Emax) with no change in volume intercept (Vo) of the left ventricular pressure-volume relationship at end systole. Neither the measured left ventricular end-diastolic pressure nor the estimated left ventricular end-diastolic volume (LVEDV) decreased with acidemia, suggesting that the reduced venous return did not result from relative hypovolemia. However, acidemic pulmonary hypertension may have interfered with the expected response to myocardial depression, which is an increase in LVEDV.

Acidosis, Lactic↗
PubMed1989

Bifurcations and intrinsic chaotic and 1/f dynamics in an isolated perfused rat heart.

The application of the theory of chaotic dynamical systems has gradually evolved from computer simulations to assessment of erratic behavior of physical, chemical, and biological systems. Whereas physical and chemical systems lend themselves to fairly good experimental control, biologic systems, because of their inherent complexity, are limited in this respect. This has not, however, prevented a number of investigators from attempting to understand many biologic periodicities. This has been especially true regarding cardiac dynamics: the spontaneous beating of coupled and non-coupled cardiac pacemakers provides a convenient comparison to the dynamics of oscillating systems of the physical sciences. One potentially important hypothesis regarding cardiac dynamics put forth by Goldberger and colleagues, is that normal heart beat fluctuations are chaotic, and are characterized by a 1/f-like power spectrum. To evaluate these conjectures, we studied the heart beat intervals (R wave to R wave of the electrocardiogram) of isolated, perfused rat hearts and their response to a variety of external perturbations. The results indicate bifurcations between complex patterns, states with positive dynamical entropies, and low values of fractal dimensions frequently seen in physical, chemical and cellular systems, as well as power law scaling of the spectrum. Additionally, these dynamics can be modeled by a simple, discrete map, which has been used to describe the dynamics of the Belousov-Zhabotinsky reaction.

Animals↗
PubMed1987

Determination of energy expenditure during heavy exercise, normal daily activity, and sleep using the doubly-labelled-water (2H2 18O) method.

Energy expenditure of four subjects was measured by the doubly-labelled-water (2H2 18O) method to determine if energy expenditure could be determined over short periods. Three subjects were studied while they performed 8 h of heavy exercise in a laboratory environment. Urine and blood samples were taken before and after exercise. Estimated energy expended during 8 h of high-intensity exercise (55% VO2 max) for three subjects was 757 +/- 118 kcal/h by the doubly-labelled-water method using urine and a two-point calculation, which compared favorably with 735 +/- 82 kcal/h obtained by respiratory gas exchange. For the fourth subject, daytime, nighttime, and daily energy expenditure was calculated by both the two-pair method and decay-curve analysis of urine and saliva samples collected in the morning and at night. Daytime and nighttime energy expenditures differed significantly (p less than 0.05).

Activities of Daily Living↗
PubMed1984

Productivity and safety in worker cooperatives and conventional firms.

This paper examines the relationship between productivity and workers' safety in firms characterized by very different types of relations in production. Arguments are developed to explain why worker cooperatives are expected to have higher productivity and lower accident rates than conventional capitalist firms. Workers who own and control their firms are expected to have a greater incentive to be efficient and a greater ability to safeguard their health than workers employed under hierarchical and alienating conditions. The hypotheses are tested by comparing carefully matched conventional and cooperative plywood companies. Preliminary results suggest that while cooperatives may be more productive they are not safer, indicating the limits of the isolated cooperative form in capitalist market economies.

Accident Prevention↗