Induction par les Rayons X de la Destruction de L'acide Désoxyribonucléique d'Escherichia Freundii

Summary

Une destruction du DNA apparaît quand E. freundii est irradiée et incubée deux heures à 37°c dans un milieu ne permettant pas sa multiplication. Cette destruction est de l'ordre de 25 pour cent quand les bactéries sont suspendues dans l'eau distillée. L'adjonction de divers sels, à des concentrations variables, au milieu de suspension, modifie la proportion de DNA détruite. Deux types d'effet protecteur ont été observés. L'un paraît lié à la pression osmotique et se manifeste quelle que soit la nature du milieu de suspension pour autant qu'il soit suffisamment concentré, l'autre est fonction du pouvoir réducteur de la substance en solution, et serait un effet anti-oxygène. De plus, certaines substances, à des concentrations comprises entre 6 × 10^?2 et 25 × 10^?3 M, accroissent la destruction du DNA. Cet effet paraît dépendre de la nature de l'anion et être plus intense avec les anions multivalents. Le mécanisme de la destruction du DNA n'est pas élucidé.     

Hydratation dans les sports de glace. Étude du jeune hockeyeur

Objectives – To study the water balance of the young ice hockey players (12 to 13 years old) during their training sessions and one match.Methods – Twenty one players of an ice hockey club  are weighed before and after two training sessions and one match in order to evaluate their water balance in these different conditions. The exact amount of water ingested by each subject during the tests is measured.Results – Water intakes vary from 0.25 ± 0.51 to 0.84 ± 0.42 l h^–1 (mean ± standard deviation) in relation to the type of effort. The percentage of players who do not drink water falls from 65% at the first training session to 0% at the second one and the match. The highest loss is observed during the match. The average heart rate varies between 145 ± 11 and 163 ± 12 beats per minute during training and 171 ± 8 beats per minute during the match. From 0 to 60% of the total time of the players is above the anaerobic threshold, which indicates a very high variability of energy expenditure.Conclusion – The water loss at the end of these tests is close to that  observed by some authors for children during physical exercise. The tests show an increase in spontaneous drinking, as, after the second trial, a full rehydration of the players is observed.     

Questionnaire de surentraînement de la Société française de médecine du sport : relations entre les échelles visuelles analogiques et le score de surentraînement chez les sportifs

Aim. – Verify the correlation between analogical visual scale (performance score or SP) and overtraining score (obtained by the number of positive items) in a sport population.Methods and results. – Ninety-nine subjects (25 women and 74 men), all international or national athletes (mean training: 12–20 h/week), have complied one to three overtraining questionnaire during the 2001–2002 sport session. Results were analysed by a comparison between analogical visual scale and overtraining score in the total population. These results showed that a correlation exits between analogical visual scale and overtraining score.Conclusion. – This questionnaire is a very interesting method for coaches, and sport doctors, allowing a good determination of physical condition and it permits to identify some fatigue state, consecutively to training variations.     

Pharmaciens d'officine et dopage sportif : enquête sur les connaissances et les attitudes au niveau de la région de Dakar au Sénégal

Aim. – Evaluate the knowledge of retail pharmacists of doping in sport and to describe their attitude in front to this phenomenon.Methods. – We proceeded by a prospective self-reported survey by postal mail with 105 retail pharmacists in Dakar which contains 299 pharmacies.Results. – We have received 68 answers. Only 10% of pharmacists know doping definition. They are 66% who think that senegalese sportsmen use doping products. They feel concerned with the problem of doping (81%) and 19% of them said having been contacted during these last 12 months for advice on doping products. They consider that doping is a kind of drug addiction and a public health problem. They estimated to 95% that the most effectiveness means of prevention would be to talk about side effects of doping products with the support of doctors.Conclusion. – This study which has to be extended must bring us to do big preventing actions.     

Effet de l'intensité de l'entraînement sur les réponses en catécholamines à l'exercice supramaximal chez des endurants de sexe masculin

Introduction – In this study we compared catecholamine responses to the Wingate-test in 2 male endurance trained groups: 6 middle distance runners (DFC) (800m and 1500m) and 6 long distance runners (DFL) (5000 m and 10,000 m).Results – As expected DFL exibited higher maximal oxygen consumption (72 ± 2,5 vs 79 ± 4,5 ml min^–1kg ^–1 fat free mass respectively for DFC and DFL) and DFC exibited higher performances during the Wingate-test (15,8 ± 0,3 vs 14,7 ± 0,4 W kg^–1 fat free mass respectively for DFC and DFL). In opposite differences between maximal catecholamine responses (Adrénaline: 3,8 ± 0,7 vs 3,5 ± 0,3 nmol l^–1. Noradrénaline: 20,4 ± 1,5 vs 16 ± 2,1 nmol l^–1 respectively for DFC and DFL) and maximal plasma lactate were not significant.Conclusion – This results suggests that endurance specificity may not induce different catecholamines responses to sprint exercise.     

Effets de l'entraı̂nement sur les potentiels aérobie et anaérobie de jeunes nageurs. Exercice réalisé avec les bras

Aims – Investigate the influence of exercise training on the aerobic and anaerobic capacities of young swimmers.Methods – Ten male swimmers aged 15.2 ± 3.8 years participated: five sprint specialists and five middle-distance specialists. Each subject performed, an arm ergocycle, two laboratory tests, a maximal incremental exercise test and a force–velocity test, once in February (T1) and then again in June (T2).Results – For all subjects combined (n=10), the results showed a significant increase in maximal anaerobic power (p < 0.01) between T1 and T2. Aerobic capacity did not change significantly between the two tests in either group.Conclusion – This study demonstrates the interest of evaluating aerobic and anaerobic capacity in young swimmers during arm exercise. The change in results over the 5-month period between the two tests indicates the importance of scheduling exercise tests during the course of athletic training programs.     

Comparaison des paramètres de la relation puissance–temps limite obtenus par différents modèles de la puissance critique

Introduction

The aim of this study was to determine how the choice of the model would affect the estimation of the parameters of the relation between power and limit time.

Synthesis of facts

Twelve volunteers have done five or six time trials on cycle ergometer making it possible to test six models: two linear forms (Lin-W et Lin-P) and one non-linear form (Nlin-2) of the simple hyperbolic model, two models with a finite limit for maximal power (Nlin-3 et EXP) and one model which distinguished the critical power and the maximal aerobic power (Mod-α). Lin-P and EXP have given the highest estimates for the critical power and Nlin-3 the lowest. No statistical difference was observed between the estimates from Lin-W, Nlin-2 and Mod-α.

Conclusion

Although Nlin-2 was better on the statistical ground and Mod-α could give more information on the anaerobic contribution according to the total power, Lin-W would be a robust method to estimate the critical power.