Performance for short intermittent runs: active recovery vs. passive recovery

International audienceThis study was designed to calculate the critical velocity (v crit ) and anaerobic distance capacity (ADC) of prepubescent children for running events. Thirty-four prepubertal children underwent a graded field test to exhaustion in order to determine peak oxygen uptake (peak [Formula: see text]) and maximal aerobic velocity (MAV). Then, in random order, they performed five runs to exhaustion (tlim) at relative velocities corresponding to 90, 95, 100, 105, and 110% of MAV. The linear relationships between distance limit (dlim) and tlim were calculated in order to determine v crit (slope of the relationship) and ADC (intercept). Very high individual coefficients of determination were found between dlim and tlim (0.98 < r 2 < 0.99; p < 0.001). The v crit was significantly correlated with peak [Formula: see text] (r = 0.73; p < 0.001). However, no relationship was found between ADC and the maximal accumulated oxygen deficit. In conclusion, our results indicated that, for children, the relationship between dlim and tlim could be calculated with tlim ranging from 2 to 10 min, and that v crit is a good indicator of the aerobic fitness of children. Nevertheless, further studies will have to be conducted to validate the use of ADC as an indicator of children's anaerobic capacity. Key words: aerobic power, anaerobic capacity, comparison, model, performanc

Structure-activity relationships, biological evaluation and structural studies of novel pyrrolonaphthoxazepines as antitumor agents

Microtubule-targeting agents (MTAs) are a class of clinically successful anti-cancer drugs. The emergence of multidrug resistance to MTAs imposes the need for developing new MTAs endowed with diverse mechanistic properties. Benzoxazepines were recently identified as a novel class of MTAs. These anticancer agents were thoroughly characterized for their antitumor activity, although, their exact mechanism of action remained elusive. Combining chemical, biochemical, cellular, bioinformatics and structural efforts we developed improved pyrrolonaphthoxazepines antitumor agents and their mode of action at the molecular level was elucidated. Compound 6j, one of the most potent analogues, was confirmed by X-ray as a colchicine-site MTA. A comprehensive structural investigation was performed for a complete elucidation of the structure-activity relationships. Selected pyrrolonaphthoxazepines were evaluated for their effects on cell cycle, apoptosis and differentiation in a variety of cancer cells, including multidrug resistant cell lines. Our results define compound 6j as a potentially useful optimized hit for the development of effective compounds for treating drug-resistant tumors