Implication des facteurs cardiorespiratoires dans l’intolérance à l’effort de l’adolescent obèse

Introduction

To identify the parameters, which can explain the effort intolerance in young obese during standard cardiorespiratory evaluation at rest and exercise.

Synthesis

Fourty-two obese (degree 2) adolescents systematically underwent pulmonary function measurements and maximal graded exercise on ergocycle. Two subgroups were drawn on the basis of their VO2peak${\text{V}}_{{\text{O}}_{\text{2peak}}}$ (‘normal’ group: N is greater than 80% of predictive value, n = 14;‘abnormal’ group: A is less than 80% of predictive value) and compared for all the measured parameters. Forced vital capacity (FVC) and forced expiratory volume in the first second (FEV₁) though in the lower normal range were lower in A compared to N (P = 0.01 and P = 0.02, respectively). At the end of maximal exercise, maximal VT/FVC (P = 0.001) and VO2peak${\text{V}}_{{\text{O}}_{\text{2peak}}}$/HR_max (P = 0.04) obtained in A are lower too. VO2peak${\text{V}}_{{\text{O}}_{\text{2peak}}}$ was correlated to lean mass and spirometric data. In addition, spirometric data correlated with VO2peak${\text{V}}_{{\text{O}}_{\text{2peak}}}$/HR_max.

Conclusion

These results emphasized the possible involvement of ventilatory factors and the stress they may impose to central cardiovascular system in exercise intolerance of obese adolescent.     

Experimental verification of beam characteristics for cyclotron-based epithermal neutron source (C-BENS)

A cyclotron-based epithermal neutron source has been developed for boron neutron capture therapy. This system consists of a cyclotron accelerator producing 1.1-mA proton beams with an energy of 30 MeV, a beam transport system coupled with a beryllium neutron production target, and a beam-shaping assembly (BSA) with a neutron collimator. In our previous work, the BSA was optimized to obtain sufficient epithermal neutron fluxes of using a Monte Carlo simulation code. In order to validate the simulation results, irradiation tests using multi-foil activation at the surface of a gamma-ray shield located behind the collimator and water phantom experiments using a collimated epithermal neutron beam were performed. It was confirmed experimentally that the intensity of the epithermal neutrons was 1.2×10⁹ cm⁻² s⁻¹.