Body position affects performance in untrained cyclists

OBJECTIVE: To compare cardiovascular and ventilatory variables in upright versus aero cycle ergometry at submaximal and maximal exercise intensities in untrained cyclists. METHOD: Ten physically active men (mean (SD) age 19.1 (1.10) years) who were unfamiliar with aerobars underwent maximal exercise testing and steady state cycling at 50, 100, and 150 W. RESULTS: Participants had significantly greater maxima for oxygen uptake (VO2), ventilation, heart rate, and workload maximum in the upright position. During steady state cycling at the three workloads, VO2 (ml/kg/min) and gross mechanical efficiency were significantly greater in the upright position. CONCLUSIONS: In untrained subjects performing with maximal effort, the upright position permits greater VO2, ventilation, heart rate, and workload maxima. Further, in the steady state, exercise cycling may be less costly in the upright position. For this reason, untrained cyclists need to weigh body position effects against the well known aerodynamic advantages of the aero position.     

Elevation of plasma fatty acids by ten-hour intralipid infusion has no effect on basal or glucose-stimulated insulin secretion in normal man

There is controversy over the effect of free fatty acids (FFAs) on insulin secretion. Previous studies have shown opposite effects of short- and long-term exposure to elevated concentrations of FFAs. We studied 8 normal subjects (mean age, 30 years; mean body mass index, 23.4 kg/m2) on 2 occasions. Each had a 10-hour overnight infusion of Intralipid 20% (Pharmacia, Milton Keynes, UK) with simultaneous infusion of heparin (0.4 U/kg body weight/min) or a control infusion of saline (150 mmol/L). Insulin secretion was assessed immediately after completion of the 10-hour infusion by an intravenous glucose tolerance test. Results were analyzed using paired ttests. Intralipid infusion caused an increase in plasma FFAs of more than 9-fold (P < .01), with a simultaneous increase in glycerol (P < .01) and hydroxybutyrate (P < .01). There was no difference in blood glucose concentrations during the infusion or intravenous glucose tolerance test. Similarly, insulin secretion was not significantly different during Intralipid infusion or in the intravenous glucose tolerance test (peak insulin achieved in glucose tolerance test, P = .51; total insulin secretion during intravenous glucose tolerance test, P = .27). In conclusion, after increasing plasma FFA concentrations over 9-fold during a 10-hour infusion of Intralipid and heparin, we found no difference in basal or glucose-stimulated insulin secretion.     

Levamisole as an immunotherapeutic agent in the treatment of cancer

Levamisole, as an immunotherapeutic agent, distinguishes itself from the bacterial immunoadjuvants in that it does not stimulate immune responses above the normal level in healthy subjects. Numerous animal and clinical studies on levamisole as an anticancer agent suggest that there is a threshold dose of levamisole (2.5 mg/kg per day for humans) which should be met in order to achieve optimum results and which should be adjusted for body weight or surface area. In addition, levamisole appears most effective on hematogenous metastases and on patients with a heavier pre-treatment tumor burden. Finally, while most cancers appear susceptible to the effects of levamisole, the drug should be used as an adjunct to classical therapeutic modalities, to stabilize complete remissions, not to induce them by itself. Therefore, immunotherapy with levamisole may be most efficacious when used as an adjuvant to other forms of cytoreductive therapy.

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Résumé Le levamisole est un agent immunothérapique qui se différencie des immuno-adjuvants bactériens: chez le sujet sain, il ne stimule pas les réponses immunes au-delà des valeurs normales. De nombreux travaux expérimentaux et cliniques consacrés aux effets anticancéreux du levamisole suggèrent qu'il existe une dose seuil (2.5 mgr/kg/j pour l'homme) qui doit Être atteinte pour obtenir des résultats optimaux et qui doit Être ajustée en fonction du poids ou de la surface corporelle. De plus, le levamisole parait Être surtout actif contre les metastases hématogènes et chez les malades ayant, avant tout traitement, une importante altération de l'état général due à la tumeur. Enfin, si la plupart des cancers semblent Être sensibles au lévamisole, célui-ci doit Être employé comme adjuvant des thérapeutiques classiques, pour stabiliser les rémissions complètes et non pour les induire. L'immunothérapie au lévamisole peut donc Être surtout efficace lorsqu'elle complète d'autres thérapeutiques de cytoréduction.

     

Urinary cadmium and lead concentrations and their relation to blood pressure in a population with low exposure

The 24 hour urinary excretion of cadmium (U-Cd) and lead (U-Pb), and the excretion of beta-2- microglobulins and retinol binding protein concentration in spot urines, were determined in a random 4% sample of the population of a small Belgian town. Blood pressure and body weight were measured on two separate occasions. U-Cd averaged 2.4 nmol/24 h in 46 youths, increased with age, and was significantly higher in 57 adult men as compared with 59 women (9.3 v 7.2 nmol/24 h; p less than 0.01). U-Pb averaged 28 nmol/24 h in youths and similarly increased with age: adult men excreted more lead than women (64 v 40.0 nmol/24 h; p less than 0.001). Among men, manual workers excreted more cadmium (12.6 v 7.5 nmol/24 h; p less than 0.05) but a similar amount of lead (62 v 61 nmol/24 h) compared with office workers. After adjusting for sex and age, U-Cd and U-Pb were not related to body weight and cigarette consumption. In simple regression analysis, U-Cd was positively correlated with both systolic (r = +0.30; p less than 0.05) and diastolic (r = +0.38; p less than 0.01) blood pressure in women. After adjusting for other contributing variables, however, a weak but negative relation became apparent between systolic pressure and U-Cd in women (t = -2.21; p = 0.033) and between diastolic pressure and U-Cd in men (t = -2.04; p = 0.047). In women urinary beta-2-microglobulin was related to diastolic pressure (r-0.44; p<0.01) and after adjusting for age to both systolic (t=2.75; p=0.009) and diastolic (t=-3.07; p=0.004) pressure. In none of the sex-age groups did U-Pb and retinol binding protein contribute to the blood pressure variability.     

Correlates of blood pressure in rural and urban Za?re

Blood pressure and anthropometric characteristics were studied in 312 rural and 675 urban Bantu of Za?re aged 10 years and more; proteinuria and the urinary sodium to potassium ratio were determined. On average, systolic and diastolic pressure were higher in rural than in urban Bantu, and rose with advancing age in both populations. However, rural Bantu were older, lighter and smaller, and had a lower sodium:potassium ratio than urban Bantu. Using multiple regression analysis, systolic and diastolic pressures correlated positively with age, weight, pulse rate, sex and sodium:potassium ratio; diastolic pressure also correlated negatively to height. After adjusting blood pressure for these independent correlates, systolic pressure remained significantly higher in rural Bantu. However, no significant difference persisted between the two populations after adjusting blood pressure for age alone. The prevalence of hypertension in rural and urban Bantu increased with age and was 14.2 and 9.9%, respectively, for participants at least 20 years old; women were more affected in the rural area, whereas men were more affected in the urban population. The occurrence of proteinuria was higher in rural Bantu than in urban; it was similar in participants with and without definite hypertension. It is suggested that higher blood pressure in the rural setting was mostly accounted for by the older age of the population.     

Comparative study of an angiotensin-II analog and a converting enzyme inhibitor

The effects of an angiotensin-II analog (saralasin, i.v.) and of a converting enzyme inhibitor (captopril, oral) were compared in 12 sodium-depleted patients with hypertension. The decrease of the mean intraarterial pressure (MAP) with captopril (-21.5 +/- [SEM] 4.3 mm Hg) was more pronounced (P < 0.001) than the change of MAP during saralasin (-10.5 +/- 4.0 mm Hg). The pretreatment arterial plasma renin activity (log PRA) was closely related to the change of MAP during saralasin (r = -0.94; P < 0.001) and also to the captopril-induced change of MAP (r = -0.82; P < 0.001); similar results were obtained for the log plasma angiotensin (PA) I and II levels. The change of MAP was more pronounced, however, with captopril than during saralasin at any level of pretreatment PRA, PAI or PAII. Saralasin did not affect heart rate (P > 0.4), but during captopril the heart rate increased by 5.1 beats/min (P < 0.001). Captopril produced a 70% decrease of PAII, but the change of MAP was poorly related to the changes of PAII (r = -0.57; P < 0.05); PRA and PAI rose threefold to fourfold. PRA, PAI, and PAII all increased during saralasin. These observations may suggest that the antihypertensive action of captopril is not based solely on the inhibition of AII formation, but also the agonistic effect of saralasin has to be considered.     

Moderate sodium restriction and diuretics in the treatment of hypertension

Using a cross-over type setup with 4 periods of 1 month each in 22 patients with mild, mostly essential hypertension, the antihypertensive action of the following therapeutic regimens were compared: (1) a regular diet and placebo (period RP), (2) a regular diet and 100 mg. hydrochlorothiazide and 100 mg. spironolactone (period RD), (3) a moderate sodium restriction and placebo (LP period), and (4) this diet together with the same diuretics (period LD). The diuretics or placebo were administered on a double blind basis, while the sodium restriction or regular sodium diet was prescribed in an open, but randomized system. The 24 hour urinary sodium averaged 191.1 ± 61.2 mEq. during the RP period and 92.8 ± 41.8 mEq. during the LP period.Compared to the RP period, the reduction in home blood pressures was more important with diuretics alone ($\text{16.1}\text{8.1}$ mm. Hg) than with this moderate sodium restriction alone ($\text{7.7}\text{4.4}$ mm. Hg), while the combination of both produced a statistically significantly (p < 0.005) higher blood pressure reduction ($\text{20.7}\text{10.8}$ mm. Hg).Not only the diuretics but also the sodium restriction increased the serum uric acid, and this could be related to the decreased urinary uric acid clearance.A significant (p < 0.001) correlation (r = 0.66) was obtained between the decrease in systolic blood pressure (expressed in mm. Hg) produced by the sodium restriction (y) and the decrease in 24 hour urinary sodium excretion (expressed in mEq.) produced by the same diet:

$\text{y=?6.58+0.163}\text{x}$

These data suggest that a reduction of the daily NaCl intake from 10 to 5 Gm. could produce a decrease of blood pressure of about $\text{10}\text{5}$ mm. Hg.