Influence du type de posture assise en classe sur le rachis et les resultats scolaires chez des ecoliers de Porto-Novo (Benin)

L’objectif de cette étude transversale réalisée à Porto-Novo est de : 1) déterminer l’effet de la posture assise de profil par rapport au tableau adoptée en classe par les écoliers sur leur courbures rachidiennes; 2) déterminer dans le même groupe, l’association entre cette posture et l’apparition des rachialgies d’une part et les résultats scolaires d’autre part. Les angles des courbures rachidiennes, le type de rachialgie et les résultats scolaires ont été comparés chez 32 écoliers des cours moyens de Porto-Novo, qui adoptent lors du travail en groupe une posture assise face au tableau (PAFT, n = 16) ou de profil par rapport au tableau (PAPT, n = 16). Les clichés radiographiques et l’enquête ont révélé que la PAFT entraîne une accentuation de la lordose cervicale (37,6 ± 7,6° vs 47,4 ± 14,5°, p = 0,02). Les cervicalgies (53,2%) sont plus fréquentes, avec un pourcentage plus élevé dans le groupe PAPT, qui enregistre également les résultats plus faibles au cours des trimestres deux et trois (p < 0,0001). S’asseoir en classe de profil par rapport au tableau accroît donc le risque d’accentuation des courbures rachidiennes, la fréquence des rachialgies et infléchit les résultats scolaires.Mots clés: Posture assise, rachis, radiographie, école primaire, résultats scolaires.ABSTRACTThe objective of this cross-sectional study carried out in Porto-Novo is to: 1) determine the effect of the profile sitting posture related to the blackboard on the schoolchildren spinal parameters; 2) determine in the same group, the association between this posture, the appearance of the back pain and the scholar results. The sitting postures, face (SFP, n = 16) or profile related to the blackboard (PSP, n = 16), the spinal curvatures, the type of back pain and the scholar results were assessed in 32 schoolchildren of the fifth and sixth forms of Porto-Novo. The radiographies of spine and the survey revealed that the SFP adopted by some schoolchildren during group-works increase a cervical lordosis (37.6 ± 7.6° versus 47.4 ± 14.5°, p = 0.02). The neck pain (53.2%) are most frequent, with a higher frequency in the PSP group which also records weak scholar results during the second and the third quarters (p < 0.0001). Profile sitting posture related to the blackboard increase the risk of stressing of the spinal curvatures, the frequency of the neck pain and inflects the scholar results.Keywords: Sitting posture, spine, radiography, primary school, scholar results

Protonation drives the conformational switch in the multidrug transporter LmrP

Multidrug antiporters of the major facilitator superfamily couple proton translocation to the extrusion of cytotoxic molecules. The conformational changes that underlie the transport cycle and the structural basis of coupling of these transporters have not been elucidated. Here we used extensive double electron-electron resonance measurements to uncover the conformational equilibrium of LmrP, a multidrug transporter from Lactococcus lactis, and to investigate how protons and ligands shift this equilibrium to enable transport. We find that the transporter switches between outward-open and outward-closed conformations, depending on the protonation states of specific acidic residues forming a transmembrane protonation relay. Our data can be framed in a model of transport wherein substrate binding initiates the transport cycle by opening the extracellular side. Subsequent protonation of membrane-embedded acidic residues induces substrate release to the extracellular side and triggers a cascade of conformational changes that concludes in proton release to the intracellular side.info:eu-repo/semantics/publishe

ABCA1, from pathology to membrane function.

The ABCA1 transporter is the prototype of the A class of mammalian adenosine triphosphate binding cassette transporters and one of the largest members of this family. ABCA1 has been originally identified as an engulfment receptor on macrophages and, more recently, it has been shown to play an essential role in the handling of cellular lipids. Indeed by promoting the effluxes of membrane phospholipids and cholesterol to lipid-poor apoprotein acceptors, ABCA1 controls the formation of high-density lipoproteins and thus the whole process of reverse cholesterol transport. A number of additional phenotypes have been found in the mouse model of invalidation of the ABCA1 gene. In spite of their clinical diversity, they all are extremely sensitive to variations in the physicochemical properties of the cell membrane, which ABCA1 controls as a lipid translocator