Time course of neuro-mechanical changes underlying stretch-shortening cycle during intermittent exhaustive rebound exercise

This study analysed the time course of neuro-mechanical changes underlying stretch?Cshortening cycle during intermittent exhaustive rebound exercise. On a sledge apparatus, ten subjects repeated until exhaustion a series of 30 unilateral submaximal rebounds, with intermediate 3-min rest periods. Rebound height, ground reaction force, 3D tibial acceleration and electromyographic activity of major lower limb muscles were recorded. A maximal drop jump test performed before and after the exhaustive exercise revealed a 10% drop in maximal stretch?Cshortening cycle (SSC) performance. Specific investigation of the neuro-mechanical changes along the exhaustive exercise included classical comparison of the first (BEG) and last (END) rebound series. From the initial accommodation phase, an optimized (OPTIM) series was individually determined as the first of at least two subsequent series with significantly shorter contact time than in the BEG series. The OPTIM series was reached after 3?±?1 series, with associated increased lower limb stiffness during the braking phase and decreased muscle activities during the push-off. The major result was that the early (BEG?COPTIM) changes explained most of the BEG?CEND ones whereas the actual (OPTIM?CEND) fatigue effects remained quite limited. This confirmed our expectation that erroneous quantification of the SSC fatigue effects might be drawn when using the early beginning of rebound exercise on the sledge as a reference. Actual fatigue effects included medio-lateral instability as suggested by increased peroneus longus preactivation and medio-lateral tibial acceleration. The present methodology is thus considered as improving the distinction between SSC optimization and its deterioration with fatigue.     

Adéquation en dialyse péritonéale : mise au point

The optimal method to assess the adequacy of peritoneal dialysis therapies is controversial. Today, the adequacy must not be considered as a number or a concept assessed only by two parameters (total KT/V urea and total solute clearance) but defined by many more items. In the absence of data, based on theoretical considerations, the reanalysis of the CANUSA study showed that renal kidney function, rather than peritoneal clearance, was associated with improved survival. Residual renal function is considered as a major predictor factor of cardiovascular mortality. Results of this reanalysis were supported by the adequacy data in ADEMEX, EAPOS and ANZDATA studies. Therefore, clinical assessment plays a major role in PD adequacy. The management of fluid balance, the regular monitoring of malnutrition, the control of mineral metabolism and particularly the glucose load, considered as the “corner-stone” of the system, are the main points to be considered in the adequacy of PD patients. The essential goal is to minimize glucose load by glucose-sparing strategies in order to reduce the neoangiogenesis of the peritoneal membrane.     

The disablement process: Factors associated with progression of disability and recovery in French elderly people

Purpose:?To study the factors associated with progression, recovery and death from different grades of disability in elderly people.

Method:?The sample included 3198 participants of the PAQUID (‘Personnes Agées QUID’) cohort, aged 65 and over and community-dwellers at baseline. Subjects were re-interviewed 1, 3, 5, 8 and 10 years after baseline. A five-state Markov model was used to estimate transition intensities between four grades of disability and toward death. We used a hierarchic scale of disability, which combines basic and instrumental activities of daily living and mobility. Several explanatory variables were investigated: medical, personal and environmental factors.

Results:?The factors associated with progression and/or no recovery of disability were cardiovascular diseases, stroke and diabetes, low cognition, visual impairment and dyspnoea (for pathologies and impairments), older age, female gender, low educational level (for risk factors), depression (for intra-individual factor) and being married, recent hospitalization and number of drugs (for extra-individual factors). Older age, male gender, tobacco consumption and living in an urban area were associated with mortality.

Conclusions:?These findings confirm the independent contribution of each group of variables in the disablement process and stress their different impact on progression of disability or on recovery from different grades of disability.     

Phylodynamics of the HIV-1 CRF02_AG clade in Cameroon

Evolutionary analyses have revealed an origin of pandemic HIV-1 group M in the Congo River basin in the first part of the XX century, but the patterns of historical viral spread in or around its epicentre remain largely unexplored. Here, we combine epidemiologic and molecular sequence data to investigate the spatiotemporal patterns of the CRF02_AG clade. By explicitly integrating prevalence counts and genetic population size estimates we date the epidemic emergence of CRF02_AG at 1973.1 (1972.1, 1975.3, 95% CI). To infer the phylogeographic signature of this clade at a regional scale, we analyze pol and env time-stamped sequence data from 10 countries using a Bayesian phylogeographic approach based on an asymmetric discretized diffusion model. Our data confirms a spatial origin of CRF02_AG in the Democratic Republic of Congo (DRC) and suggests that viral dissemination to Cameroon occurred at an early stage of the evolutionary history of CRF02_AG. We find considerable support for epidemiological linkage between neighbour countries. Compilation of ethnographic data suggested that well-supported viral migration did not reflect sustained human migratory flows. Finally, using sequence data from 15 locations in Cameroon, we use relaxed random walk models to explore the spatiotemporal dynamics of CRF02_AG at a finer geographical detail. Phylogeographic dispersal in continuous space reveals that at least two distinct CRF02_AG lineages are circulating in overlapping regions that are evolving at different evolutionary and diffusion rates. In conclusion, by combining molecular and epidemiological data, our results provide a time scale for CRF02_AG, early 70s, place its spatial root in the DRC within the putative root of group-M diversity and propose a scenario of chance-exportation events for the spatiotemporal patterns of a successful HIV-1 lineage both at a regional and country-scale.