Continuum de prévention des blessures sportives chez les jeunes athlètes, en collaboration avec les Jeux du Québec 2014

Travail d'intégration présenté à la Faculté de médecine en vue de l’obtention du grade de maîtrise en physiothérapieIntroduction/problématique : La participation des jeunes aux sports est en ascension constante depuis plusieurs années. C’est pourquoi l’équipe médicale des Jeux du Québec de Longueuil 2014 nous a consultés pour approfondir le système de surveillance actuel et les moyens pour prévenir les blessures. Objectifs : Définir les blessures les plus fréquentes dans les différentes disciplines des Jeux. Établir les composantes d’un système de surveillance adapté aux événements sportifs. Informer les athlètes, entraîneurs et parents sur la prévention des blessures. Stratégie méthodologique : Recension de la littérature dans les bases de données PubMed, Medline, Cinhal, Psychinfo. Résultats : Nous avons élaboré des fiches sur les blessures les plus fréquentes dans les sports chez les jeunes. Également, une définition du mot blessure a été conçue et a permis la création d’une grille d’intervention sur le terrain. Nous avons établi des lignes directrices sur les différentes modalités de prévention en physiothérapie pour la tendinopathie à l’épaule et l’entorse à la cheville chez les jeunes. Aussi, des recommandations sur les comportements à adopter chez les parents afin de diminuer le risque de blessures ont été proposées. Conclusion : Il est nécessaire que chaque personne impliquée auprès des athlètes agisse vers un même but : la prévention. Donc, nous recommandons aux Jeux du Québec d’effectuer une collecte de données à partir de la grille basée sur l’épidémiologie pour assurer un meilleur suivi des blessures. De plus, des recommandations sur la prévention seront mises sur le site Internet des Jeux

Paleointensity of the Geomagnetic Field During the Last 80,000 Years

International audienceHigh-resolution records of the relative paleointensity of the geomagnetic field have been obtained from five marine cores. Three duplicate records were used to estimate the regional coherency of the data within a single area (Tyrrhrenian Sea) while the two others document the field variations in the eastern Mediterranean and the southern Indian Ocean. Careful investigations of distinct rock magnetic parameters have established the downcore unifornfity of the sediments in terms of magnetic nfineralogy and grain sizes. The time-depth control was provided by oxygen isotopes, and small-scale variations in the deposition rates were constrained by means of tephrachronology. The synthetic curve calculated from the Mediterranean records provides a continuous record of the intensity variations during the last 80,000 years (80 kyr), which correlates well with the sparse volcanic data available for the period 0-40 kyr. The fact that identical behavior is seen in both data sets and that they also compare quite well with results from a core collected in the Pacific Ocean establishes the truly dipolar character of these variations. The dipole field moment is characterized by large-scale changes as shown by the existence of pronounced drops (at 39 and 60 kyr) alternating with periods of higher intensity. The record suggests a periodic nature for these intensity variations; however, the period studied is not sufficiently long to state this conclusively. These results demonstrate the potential of sediments for such studies and constitute a first step towards obtaining a global paleointensity record over a long period of time

The Blake geomagnetic event: transition geometry, dynamical characteristics and geomagnetic significance.

International audienc

Apelin and APJ regulation in adipose tissue and skeletal muscle of type 2 diabetic mice and humans.

International audienceApelin, an adipocyte-secreted factor upregulated by insulin, is increased in adipose tissue (AT) and plasma with obesity. Apelin was recently identified as a new player in the control of glucose homeostasis. However, the regulation of apelin and APJ (apelin receptor) expression in skeletal muscle in relation to insulin resistance or type 2 diabetes is not known. Thus we studied apelin and APJ expression in AT and muscle in different mice models of obesity and in type 2 diabetic patients. In insulin-resistant high-fat (HF)-fed mice, apelin and APJ expression were increased in AT compared with control. This was not the case in AT of highly insulin-resistant db/db mice. In skeletal muscle, apelin expression was similar in control and HF-fed mice and decreased in db/db mice. APJ expression was decreased in both HF-fed and db/db mice. Control subjects and type 2 diabetic patients were subjected to a hyperinsulinemic-euglycemic clamp, and tissues biopsies were obtained before and at the end of the clamp. There was no significant difference in basal apelin and APJ expression in AT and muscle between control and diabetic patients. However, apelin plasma levels were significantly increased in diabetic patients. During the clamp, hyperinsulinemia increased apelin and APJ expression in AT of control but not in diabetic subjects. In muscle, only APJ mRNA levels were increased in control but also in diabetic patients. Taken together, these data show that apelin and APJ expression in mice and humans is regulated in a tissue-dependent manner and according to the severity of insulin resistance

Autotaxin is released from adipocytes, catalyzes lysophosphatidic acid synthesis, and activates preadipocyte proliferation. Up-regulated expression with adipocyte differentiation and obesity

Our group has recently demonstrated (Gesta, S., Simon, M., Rey, A., Sibrac, D., Girard, A., Lafontan, M., Valet, P., and Saulnier-Blache, J. S. (2002) J. Lipid Res. 43, 904-910) the presence, in adipocyte conditioned-medium, of a soluble lysophospholipase d-activity (LPLDact) involved in synthesis of the bioactive phospholipid lysophosphatidic acid (LPA). In the present report, LPLDact was purified from 3T3F442A adipocyte-conditioned medium and identified as the type II ecto-nucleotide pyrophosphatase phosphodiesterase, autotaxin (ATX). A unique ATX cDNA was cloned from 3T3F442A adipocytes, and its recombinant expression in COS-7 cells led to extracellular release of LPLDact. ATX mRNA expression was highly up-regulated during adipocyte differentiation of 3T3F442A-preadipocytes. This up-regulation was paralleled by the ability of newly differentiated adipocytes to release LPLDact and LPA. Differentiation-dependent up-regulation of ATX expression was also observed in a primary culture of mouse preadipocytes. Treatment of 3T3F442A-preadipocytes with concentrated conditioned medium from ATX-expressing COS-7 cells led to an increase in cell number as compared with concentrated conditioned medium from ATX non-expressing COS-7 cells. The specific effect of ATX on preadipocyte proliferation was completely suppressed by co-treatment with a LPA-hydrolyzing phospholipase, phospholipase B. Finally, ATX expression was found in mature adipocytes isolated from mouse adipose tissue and was substantially increased in genetically obese-diabetic db/db mice when compared with their lean siblings. In conclusion, the present work shows that ATX is responsible for the LPLDact released by adipocytes and exerts a paracrine control on preadipocyte growth via an LPA-dependent mechanism. Up-regulations of ATX expression with adipocyte differentiation and genetic obesity suggest a possible involvement of this released protein in the development of adipose tissue and obesity-associated pathologies

An attempt to constrain the age, duration, and eruptive history of the Karoo flood basalt: Naude's Nek section (South Africa)

We have carried out paleomagnetic sampling of a ∼750 m sequence of the Karoo large igneous province (Naude's Nek Pass, South Africa). K-Ar dating (Cassignol-Gillot) has been performed on four samples from the 650 m upper unit (mean age 179.2 ± 1.8 Ma) and a sample from the lower unit (184.8 ± 2.6 Ma). A succession of two phases of volcanism is suggested. The lower 25 flows (115 m thick) have recorded a reversed polarity; the next 23 flows (135 m thick) are transitional and contribute a detailed record of the “Van Zijl” (1962) Jurassic reversal. The upper 38 flows (500 m thick) have normal polarity. Directional groups (DGs) of lava flows with quasi-identical remanence directions indicate eruption durations too short to have recorded geomagnetic secular variation and hence are interpreted as single eruptive events. Altogether, 19 DGs and 10 sheet lobes yield a sequence of 29 distinct directions. This could correspond to a total eruptive activity shorter than 3000 years, less than one per mil of the total duration over which the section was emplaced. We obtain a new paleomagnetic pole for South Africa at ∼180 Ma (λ = 75.2°N, ϕ = 276.4°E, A95 = 5.8°, N = 19), which is consistent with earlier reports