Dexamethasone in resting and exercising men. I. Effects on bioenergetics, minerals, and related hormones.

A placebo and a low and a high dose of dexamethasone (Dex) were administered for 4.5 days, at 3-wk intervals, to 24 healthy men, following a double-blind, random-order, crossover procedure. After the last dose the subjects performed a maximal cycling exercise, during which respiratory exchanges, electrocardiogram, and blood pressures were monitored. Blood was sampled just before and after each exercise bout. Dex showed no significant effect on fitness, sleep, exhaustion during exercise, maximal O(2) consumption, ventilatory threshold, maximal blood lactate, or rest and exercise blood pressures. On the contrary, both doses of Dex significantly decreased heart rate at rest and during maximal exercise. Blood glucose at rest was higher after both doses of Dex than after placebo; the opposite was found during exercise. Blood levels of ACTH, beta-endorphin, cortisol, and cortisol-binding globulin were lowered by Dex at rest and after exercise. Dex stimulated the increase in atrial natriuretic factor during exercise and lowered rest and postexercise aldosterone. Finally, no difference between "fit or trained" and "less fit or untrained" subjects could be found with respect to Dex effects.

Dexamethasone in resting and exercising men. II. Effects on adrenocortical hormones.

This study presents the reactions of adrenocorticosteroids (cortisol and aldosterone) and sex steroids [testosterone, androstenedione, and dehydroepiandrosterone and its sulfate (DHAS)] 1) to a dexamethasone (Dex) treatment, which is expected to lower steroid levels via the ACTH blockade, and 2) to an exercise bout at maximal O(2) consumption, which is expected to increase steroid production via ACTH stimulation. Consistent with the decrease in ACTH, all steroids except testosterone reacted negatively to Dex, independently of the dose (0.5 and 1.5 mg administered twice daily for 4.5 days). After exercise, plasma ACTH rose to 600% of basal value, resulting in a significant increase in aldosterone and adrenal androgens, but cortisol and DHAS were unaffected. This apparently surprising result can be explained by differences in peripheral metabolism: a theoretical calculation predicted that after 15 min the increase in hormone concentration may only reach 12% for cortisol and 2% for DHAS. For cortisol and adrenal androgens, assays were carried out using plasma and saliva. The consistent results obtained from the two matrices allow us to consider salivary assays as a useful tool for steroid abuse detection.

[Psychometric evaluation of depression in the elderly subject: which instruments? What are the future perspectives?]. / Evaluation psychométrique de la dépression du sujet âgé: quels instruments? Quelles perspectives d'avenir?

Depression in the elderly is frequent but often unknown (in 30 to 50% of the cases) because of difficulties in detecting or diagnosing it. This is due to the clinical features and prognosis of depression in this kind of population but also to the non-existence of specific diagnostic tests. Most of the authors consider that the most useful diagnostic tests are screening assessments. Some are rating scales that have been validated in general population then secondarily in the elderly: Hamilton Rating Depression Scale (HDRS), Montgomery & Asberg Depression Rating Scale (MADRS), Zung Self Rating Depression Scale (Zung SDS), Beck Depression Inventory (BDI) or Center for Epidemiological Studies Depression Scale (CES-D). They usually involve biases linked to age and more particularly to somatic items; and the educational level required to answer is too high for this population. However, the MADRS is still interesting for measuring change under treatment and the CES-D for detection of depressive elderly. On the other hand, some screening scales are specific of depression in the elderly. The most commonly used is the GDS (Geriatric Depression Scale) with 30 items. Some points have been discussed to increase the achievement of these methods. For example, inventories are better than interviews and should be integrated into semi-standardized interviews which do not last more than 30 minutes. The quotation 'yes' or 'no' is preferable. The instrument have to be short but have to contain specific items for depression in the elderly. Several short forms are already validated or in progress such as GDS with 15 items and, recently, with 4 items, BASDEC, short Zung IDS, BDI with 13 items and DGDS. However, these screening scales loose a part of their validity in the moderate or severe demented elderly. Few instruments can screen depression in a demented population although depression and dementia syndromes are frequently associated. Some of the inventories used are not specific: they evaluate the general psychopathology in the elderly and contains subscales which screen depression or organic brain disease. Thus, GMS-AGECAT Package, CAMDEX, CARPER, BAS are often used by the Anglo-Saxons. At present, only one specific instrument has been validated: the Cornell Scale for Depression in Dementia. Recently, new screening instruments have been put forward: Dementia Mood Assessment Scale and Canberra Interview for the elderly which seem interesting but need further studies.

A method for determining the maximal steady state of blood lactate concentration from two levels of submaximal exercise.

The aim of this study was to estimate the characteristic exercise intensity (WCL) which produces the maximal steady state of blood lactate concentration (MLSS) from submaximal intensities of 20 min carried out on the same day and separated by 40 min. Ten fit male adults [maximal oxygen uptake (VO2max) 62 (SD 7) ml.min-1.kg-1] exercised for two 30-min periods on a cycle ergometer at 67% (test 1.1) and 82% of VO2max (test 1.2) separated by 40 min. They exercised 4 days later for 30 min at 82% of VO2max without prior exercise (test 2). Blood lactate was collected for determination of lactic acid concentration every 5 min and heart rate and O2 uptake (VO2) were measured every 30 s. There were no significant differences at the 5th, 10th, 15th, 20th, 25th, or 30th min between VO2, lactacidaemia, and heart rate during tests 1.2 and 2. Moreover, we compared the exercise intensities (WCL) which produced the MLSS obtained during tests 1.1 and 1.2 or during tests 1.1 and 2 calculated from differential values of lactic acid blood concentration ([la-]b) between the 30th and the 5th min or between the 20th and the 5th min. There was no significant difference between the different values of WCL [68 (SD 9), 71 (SD 7, 73 (SD 6), 71 (SD 11)% of VO2max] (ANOVA test, P < 0.05). Four subjects ran for 60 min at their WCL determined from periods performed on the same day (test 1.1 and 1.2) and the difference between the [la-]b at 5 min and at 20 min (delta ([la-]b)) was computed.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin-converting enzyme inhibition does not suppress plasma angiotensin II increase during exercise in humans.

Physical effort stimulates the reninangiotensin system (RAS). We studied the effect of an angiotensin-converting enzyme inhibitor (ACE inhibitor) in a double-blind placebo-controlled study, on eight volunteers undergoing physical stress on an ergometric bicycle. The effects of captopril (C) (50 mg, three times daily for 3 days) on arterial pressure (AP), O2 consumption (VO2), variations in auricular natriuretic factor (ANF), renin, angiotensin II (AII) plasma levels, as well as glomerular filtration rate (GFR) and microalbuminuria (MA) were evaluated. The different parameters were compared by analysis of variance (ANOVA). The pressure profile and VO2 were not modified by ACE inhibitor. Exercise stimulates release of renin; this action was greater with captopril administration (treatment effect: p < 10(-4), indicating blockade of the RAS. This inhibition was incomplete because AII levels increased markedly when captopril was given (no treatment effect: p < 0.37). Finally, ACE inhibitor resulted in decreased GFR (p = 115 +/- 5.8 ml/mn-1, C = 91.1 +/- 4, p < 0.05) with exercise without modification of MA. ACE inhibitor administration does not modify the physical performance of nonathletic subjects; AII is significantly increased with exercise despite captopril treatment; ACE inhibitor decreases GFR significantly but does not influence MA with prolonged physical effort.

[Blood lactate in the steeplechase horse: triangular and rectangular series of steps during short duration races]. / Lactatémie chez le cheval de concours hippique: enchainements triangulaires et rectangulaires d'échelons de courses de courte durée.

Five steeplechase race horses were observed during incremental and constant-load exercises with the aim of separating effects of work rate and time on blood lactate. Each independent exercise (an incremental and three constant load tests) was a sequence of three two-minute runs, separated by two one-minute rest intervals for jugular blood sampling. The following observations were made: 1. During constant load exercises, in the five horses, blood lactate stabilized below 4 mmol.l-1: lactatemia critical velocity (LVC) = 3.33 +/- 0.16 mmol.l-1. Nevertheless, VCL, critical lactate velocity inducing LVC, was not statistically different from VS4, velocity inducing a 4 mmol.l-1 blood lactate during incremental tests. Remaining reticent on the meaning of "lactate threshold" often attributed to VS4, an incremental exercise thus seemed pertinent for routine long-term surveys of endurance. 2. If delta L is the blood lactate increase within a single short run, delta L increases linearly with running velocity for an incremental test, allowing the calculation of a "null" velocity, the highest velocity for which there is no significant lactate increase. For independent runs, delta L increased exponentially with velocity, with noticeable differences between horses. This individual short-term functional adaptation variability could be considered in assessment and follow-up of race horse fitness.

[The value of respiratory function tests in the surveillance of asthmatic children]. / Intérêt de l'exploration fonctionnelle respiratoire dans la surveillance des enfants asthmatiques.

The purpose of pulmonary function testing in children with asthma is to search for obstructive airway disease. We examined the charts of 169 asthmatic children during intervals between acute exacerbations. The severity of asthma was determined according to VIALATTE classification, with the Tiffeneau ration FEV1/VC (1) and the MMFR/VC ratio serving as obstructive indices. According to these data, children were classified into three groups: normal children (normal FEV1/VC and MMFR/VC), children with probable obstruction of the distal airways (normal FEV1/VC and decreased MMFR/VC), and children with both proximal and distal airway obstruction (decreased FEV1/VC and MMFR/VC). Since suggested normal values vary in the literature, we compared FEV1 and MMFR to determine as accurately as possible the number of children with obstructive disease. The relationship between the degree of clinical involvement and pulmonary function testing results was studied. Clinically, asymptomatic children with suspected normal respiratory function had evidence of obstructive disease in two out of three cases, and would benefit from drug therapy.

[Stability and variation of the maximal ventilation and maximal expiratory volume ratios]. / Stabilité et variation du rapport entre ventilation maximale et VEMS

The level of stability of the ratio (alpha coefficient) of maximal ventilation (MBC) over maximal expiratory volume per second (FEV1) was continued statistically for its practical value in estimating the respiratory functional incapacity. Three observations were made: --the mean value of the alpha coefficient=MBC/FEV1 is independent of the sex, age, size or weight in the normal subject; alpha was slightly higher than that found from theoretical values of MBC (CECA) and FEV1 (BALDWIN and COURNAND); --the alpha coefficient varied with the vital capacity (VC) and with FEV1; --there was a particularly simple relation between alpha and VC: alpha decreased from 38 to 30 when VC increased from 1 to 6 litres.