HL7: here and now. Part II.
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Biomedical subjects
Publications and source records attributed to V Bond.
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This study investigated the effects of diets containing fish oil or pectin on blood pressure and lipid metabolism in the deoxycorticosterone acetate (DOCA)-salt hypertensive rat. Three groups (8 rats/group) of unilaterally nephrectomized rats were fed for 21 d one of three purified diets: a) 8% fish oil + 2% safflower oil + 5% alpha cellulose (fish oil diet), b) 10% safflower oil + 5% pectin (pectin diet), or c) 10% safflower oil + 5% alpha cellulose (control diet). Each of the diets contained 6% NaCl and all rats received DOCA (30 mg/kg body wt, subcutaneously) twice weekly. Systolic blood pressure of rats fed fish oil was significantly lower (P less than 0.05) than that of rats fed the control diet; there was no significant difference between the pectin and control groups. Plasma renin activity and net sodium and potassium balances were similar among the three groups. Plasma total cholesterol, LDL cholesterol and HDL cholesterol were significantly lower (P less than 0.05) in the group fed the fish oil diet than in the group fed the control diet. Total, LDL and HDL cholesterol did not differ between rats fed the pectin and rats fed the control diet. Plasma triglyceride concentration did not differ among the three groups. Thus, dietary fish oil attenuated the development of DOCA-salt hypertension, unrelated to alterations of net sodium balance. Fish oil feeding also lowered total, LDL and HDL cholesterol, but did not alter the HDL/LDL ratio. In contrast, dietary pectin exerted no effect on blood pressure or lipid metabolism.
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The purpose of this study was to investigate the effects of caffeine on maximum voluntary contractions of the dominant knee extension and flexion muscles in 12 male intercollegiate track sprinters. Caffeine (5 mg.kg-1) and placebo (225 mg methylcellulose) gelatin capsules were administered orally in randomly assigned order. Muscle function was measured isokinetically by a Cybex II dynamometer interfaced with a data reduction computer. Six repetitions maximum of the extensors and flexors were performed at three sequential ordered speeds (30 degrees, 150 degrees and 300 degrees s-1) with a one-minute rest between varying velocities. Peake torque and power were than assessed after treatment conditions, as well as a fatigue index calculated from a series of 60 repetitions maximum ato 150 degrees s-1. Results of the 2 X 3 ANOVA and paired t-test indicated no difference in measures of peak torque and power at the varying contracting velocities and fatigue index after caffeine ingestion. These findings indicate the ingestion of caffeine in a small dose exerts no ergogenic effect on muscle function under anaerobic conditions.
Previous studies have shown that maximal oxygen uptake (VO2 max) measured during two-arm cranking and one-leg cycling is about 70-78 per cent of VO2 max measured during two-leg cycling. The present study investigated the maximal physiological responses of eight healthy untrained males during two-arm, one-leg, and two-leg ergometric exercise. Two-arm cranking and one-leg cycling were found to be 55 and 66 per cent of two-leg VO2 max, respectively. The % VO2 max at which the anaerobic threshold occurred during the two-arm and one-leg exercise conditions were 57 and 68 per cent, respectively. These findings suggest that when the active muscle mass is limited, a progressive exercise test using one leg may elicit a higher VO2 max than with two arms.
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Twelve males (six moderate drinkers and six abstainers) were studied for the influence of varying dosages of alcohol on cardiorespiratory function and work performance. The subjects underwent three separate maximal exercise tests which consisted of progressive workloads on the bicycle ergometer. Prior to each work bout the subject consumed either a placebo (0.0 ml.kg-1), small (0.44 ml.kg-1), or a moderate (0.88 ml.kg-1) dose of a 95 per cent ethanol solution. Analysis of the results indicated that the ingestion of a small or moderate amount of alcohol had no significant effect on heart rate, blood pressure, ventilation, oxygen uptake or work performance.
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The purpose of this study was to compare muscle fibre type proportions and capillary density in untrained, college-aged blacks (n = 14) and whites (n = 14). Both groups were similar in terms of peak oxygen uptake (VO2peak), measured during cycle ergometry (blacks: 42.6 +/- 4, whites: 44.3 +/- 4 ml.kg-1 min-1, mean +/- SD). Muscle samples were obtained from the quadriceps femoris (vastus lateralis) by the needle biopsy technique. Fibre type was determined by myosin ATPase stain (pH = 4.54) and capillaries were identified by amylase-periodic acid Schiff (PAS) stain. The percentage of type I, IIa, and IIb fibres in the blacks was 39.5 +/- 11.5, 40.0 +/- 8.4, and 22.8 +/- 9.8, respectively. In whites the percentage of type I, IIa, and IIb fibres was 44.9 +/- 8.5, 36.6 +/- 6.9, and 18.3 +/- 9.6, respectively. No significant differences were noted between the two racial groups for type I, IIa, or IIb fibres. Capillary density was 277 +/- 39/mm2 in the blacks compared to 289 +/- 32/mm2 in the whites. Capillary density was positively correlated to percentage of type I fibres (r = 0.497) and negatively correlated to percentage of type IIa fibres (r = -0.389), in the overall study population. These data suggest that if racial differences in fibre type do exist, such differences are small compared to the variability in this measure.
Sixteen African American females were evaluated for body fat to assess the accuracy of several practical methods of estimation: near-infrared interactance, bioelectrical impedance, and Sloan and Jackson skinfold equations. Most methods produced different results from hydrostatic weighing and produced different body fat values from each other suggesting that practical methods do not provide accurate measurements.
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The aim of our study was to examine whether there is an association between blood pressure reactivity to the cold pressor test in African Americans who engaged in different levels of physical activity. We examined the systolic pressure, diastolic pressure, mean arterial blood pressure, heart rate, cardiac index, total peripheral resistance, and forearm blood flow during a two-minute cold pressor test in 15 aerobic, physically active and 15 physically inactive, normotensive young adult African-American males. Peak oxygen consumption varied as a function of physical activity, and was significantly higher in the physically active than in the physically inactive subjects (54.5 +/- 1.5 vs 36.8 +/- 0.7 ml kg(-1) min(-1)) (P<.05). During the cold pressor test, consisting of immersing the foot in ice water, the change in cardiovascular responses were similar between the physically active and the physically inactive groups. These results suggest that regular physical activity may not contribute to an attenuated blood pressure response to behavioral stress of the cold pressor test in normotensive young adult African-American males.