Afrique de l'Est : l'empire dans tous ses états

L'Afrique de l'Est offre trois exemples de représentations impériales plaquées sur des réalités locales par un imaginaire européen marqué d'orientalisme : l'Éthiopie du mythique " Prêtre Jean " puis du roi Salomon, les ruines de Zimbabwe et le Monomotapa, les royaumes des Grands lacs et la légende des Bacwezi. Aux XIXe et XXe siècles ces " empires " sont instrumentalisés aussi par les élites africaines

Afrique de l'Est : l'empire dans tous ses états

International audienceImperial statements in East Africa East Africa offers three examples of imperial representation in which European Orientalism imagery seems to have been superimposed onto local realities : Ethiopia’s mythical “Prester John” and the King Solomon, the ruins of Zimbabwe and Monomotapa, the kingdoms of the Great Lakes and the legend of Bacwezi. In the 19th and 20th centuries these “empires” were also exploited for their own ends by African elites.L’Afrique de l’Est offre trois exemples de représentations impériales plaquées sur des réalités locales par un imaginaire européen marqué d’orientalisme : l’Éthiopie du mythique « Prêtre Jean » puis du roi Salomon, les ruines de Zimbabwe et le Monomotapa, les royaumes des Grands lacs et la légende des Bacwezi. Aux xix e et xx e siècles ces « empires » sont instrumentalisés aussi par les élites africaines

Informations contenues dans les courriers des médecins traitants adressant leurs patients de plus de 75 ans à l'hôpital

BREST-BU Médecine-Odontologie (290192102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Suivi à long terme des troubles du rythme auriculaire après valvuloplastie mitrale

BREST-BU Médecine-Odontologie (290192102) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Propriétés électrophysiologiques des canaux sodiques du muscle strié squelettique et contrainte mécanique

Les canaux sodiques dépendants du potentiel (Na) sont responsables du déclenchement et de la propagation du potentiel d action musculaire. Ils participent ainsi à l excitabilité de la fibre musculaire et à ses propriétés contractiles. L immobilisation musculaire induit des changements du phénotype contractile. Nous avons étudié l effet de 4 et 8 semaines d immobilisation du muscle Peroneus Longus (PL) à sa longueur optimale, sur ses propriétés contractiles et les propriétés électrophysiologiques de ses canaux sodiques. Après 4 semaines d immobilisation, les propriétés contractiles du muscle présentent une conversion vers un phénotype plus rapide avec un retour partiel vers les propriétés du muscle contrôle après 8 semaines d immobilisation. Les courants provenant du canal sodique de type 1.4 (Nav 1.4) augmentent puis diminuent, alors que les courants et l expression du Nav 1.5 diminuent continuellement au cours de l immobilisation. Ces résultats indiquent que la possibilité pour un muscle de se raccourcir ou de s allonger est indispensable pour conserver son phénotype contractile et maintenir le ratio Nav 1.4/ Nav 1.5. L expression du Na 1.4 est corrélée avec le phénotype rapide du muscle. Pour étudier l hypothèse d une participation des Na au phénotype contractile de la fibre musculaire, des fibres dissociées de muscles de la patte de rats Wistar ont été étudiées par la technique du macropatch-clamp, puis l isoforme de chaîne lourde de myosine (CLM) qu elles exprimaient a été déterminé par électrophorèse SDS-PAGE. Dans les fibres de PL, le courant sodique maximal (Imax) et la conductance sodique maximale (gNa max) augmentent selon le schéma suivant: type I->IIa->IIx->IIb de CLM. Ce résultat est cohérent avec une activation progressive des différents types de fibres (du type lent vers le type rapide) dans un muscle mixte comme le PL. En se contractant, le muscle soumet sa membrane à des variations de longueur donc de tension. Il est licite de s intéresser à l effet de ces variations de tension sur le fonctionnement des protéines membranaires comme les Nav. En configuration patch-clamp, nous avons appliqué, dans un ordre aléatoire, différents niveaux de dépression (0, -10, -20, -30 mmHg) sur la membrane. Le courant sodique maximal (Imax) et la conductance sodique maximale augmentent avec le niveau de dépression. Les courbes d activation sont décalées vers les potentiels négatifs avec la dépression. Le processus d inactivation lente des Nav est augmenté par la dépression. Sur le plan fonctionnel, ces résultats sont en faveur d une participation des Nav au phénomène de stretch-activation (augmentation de la force produite d un muscle par son étirement préalable). Toutefois la diminution du nombre de canaux activables (inactivation lente) par l étirement membranaire permet, à moyen terme, de moduler l excitabilité et donc la fatigabilité du muscle.Voltage-gated sodium channels (Nav) are involved in the triggering and the propagation of muscle action potential. The electrophysiological properties of Nav determine muscle excitability and influence the contractile properties of muscle. Muscle immobilization leads to modification in its fast/slow contractile phenotype. Therefore, we studied the effects of single immobilization on the contractile and the electrophysiological properties of Na, in rat muscle Peroneus Longus (PL). After 4 weeks of immobilization, PL shows a faster phenotype with partial recovery to control phenotype between 4 and 8 weeks of immobilization. Using the patch-clamp technique, sodium currents from Nav 1.4 displays a transitory increase alter 4 weeks of immobilization, whereas Nav 1.5 currents decrease continuously throughout immobilization. Our results indicate that a muscle immobilized at optimal functional length with the preservation of neural inputs, exhibits a transient fast phenotype conversion. Nav 1.4 expression and current are related to the contractile phenotype variation through muscle excitability. The myosin heavy chain (MHC) isoform determines the shortening velocity of muscle fibre. Whole muscle, even if selected according to its predominant mechanical properties ( slow or fast ), exhibits heterogeneous MHC composition. Since the properties of Na, are different between fast and slow muscles, we hypothesised that the electrophysiological properties of Na, could be related to MEC isoform expression in single muscle fibre. Alter patch-clamp recordings, single fibres were identified by SDS-PAGE electrophoresis according to their myosin heavy chain isoform (slow type I and the three fast types IIa, IIx, IIb). The maximal sodium current and conductance increase according to the scheme I->IIa->IIx->IIb. These data are consistent with the earlier recruitment of slow fibres in a fast-mixed muscle like PL. Slow fibres have to be activated early in order to optimize the mechanical performance of the predominant fast fibres. The contraction of skeletal muscle to produce force implies length and tension variation for its membrane. The consequences of tension variation on the properties of membrane proteins such as sodium channels remain questioning. In patch-clamp configuration, different levels of depression were applied with the pipette to stretch muscle membrane and Nav. Membrane stretch increases maximal sodium current and induces a leftward shift in activation and slow inactivation curves in a dose-dependent manner. Nav are involved in the stretch-activation process through the enhancement of its activation threshold with membrane stretch.BREST-BU Médecine-Odontologie (290192102) / SudocSudocFranceF

Cultured heart cells from oyster : an experimental approach for evaluation of the toxicity of the marine pollutant tributyltin

European Community regulations on chemicals promote alternative methods to test substances presenting potential risks for the environment. In the present work, cultured atrial cells isolated from oyster (Crassostrea gigas) were used as an experimental model to investigate the toxicity of tributyltin (TBT) after short-time exposure at concentrations representative of those that can be measured in seawater, marine sediments and/or bivalves bioaccumulating this pollutant. In vitro and in vivo assays produce values of the same order of magnitude for both animal/cell survival and heart/cardiomyocyte beating rate. The survival rate of whole animals decreased from 10(-6) M TBT after 3 days. For cultured cells, the viability, evaluated using 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, significantly decreased after two days of treatment with 10(-6) M TBT, and after six days with 10(-10) M TBT. The percentage of apoptotic cells, quantified by flow cytometry and YO-PRO (R)-1 iodide, a nucleic acid stain that only permeates cells that are beginning to undergo apoptosis, increased significantly in these cases. Moreover, intracellular concentration of Ca++ had increased after 10 min of exposition to 10(-6) M, and could be associated with apoptotic processes. As patch clamp experiments showed that Ca++ conductance was decreased, intracellular calcium increase could mainly be due to a release from internal stores. The decreases in beating rhythm could be explained by the decrease in adenosine triphosphate (ATP) production revealed by P-31 nuclear magnetic resonance (NMR) spectroscopy and confirmed by the increase of the K-ATP channel conductance. The related hyperpolarization and the disturbances of the energetic metabolism were clearly related to the loss of the atrial cell contractility and viability

Cultured heart cells from oyster : an experimental approach for evaluation of the toxicity of the marine pollutant tributyltin

European Community regulations on chemicals promote alternative methods to test substances presenting potential risks for the environment. In the present work, cultured atrial cells isolated from oyster (Crassostrea gigas) were used as an experimental model to investigate the toxicity of tributyltin (TBT) after short-time exposure at concentrations representative of those that can be measured in seawater, marine sediments and/or bivalves bioaccumulating this pollutant. In vitro and in vivo assays produce values of the same order of magnitude for both animal/cell survival and heart/cardiomyocyte beating rate. The survival rate of whole animals decreased from 10-6 M TBT after 3 days. For cultured cells, the viability, evaluated using 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT) assay, significantly decreased after two days of treatment with 10-6 M TBT, and after six days with 10-10 M TBT. The percentage of apoptotic cells, quantified by flow cytometry and YO-PRO®-1 iodide, a nucleic acid stain that only permeates cells that are beginning to undergo apoptosis, increased significantly in these cases. Moreover, intracellular concentration of Ca++ had increased after 10 min of exposition to 10-6 M, and could be associated with apoptotic processes. As patch clamp experiments showed that Ca++ conductance was decreased, intracellular calcium increase could mainly be due to a release from internal stores. The decreases in beating rhythm could be explained by the decrease in adenosine triphosphate (ATP) production revealed by 31 P nuclear magnetic resonance (NMR) spectroscopy and confirmed by the increase of the KATP channel conductance. The related hyperpolarization and the disturbances of the energetic metabolism were clearly related to the loss of the atrial cell contractility and viability

Hemodynamic effects of lipid emulsion after local anesthetic intoxication may be due to a direct effect of fatty acids on myocardial voltage-dependent calcium channels.

International audienceno abstrac

Noninvasive diagnosis of pulmonary embolism.

International audienceBACKGROUND: We designed a simple and integrated diagnostic algorithm for acute pulmonary embolism (PE). Diagnosis was based on clinical probability assessment, plasma D-dimer testing, then sequential testing to include lower limb venous compression ultrasonography, ventilation perfusion lung scan, and chest multidetector CT (MDCT) imaging. METHODS: We included 321 consecutive patients presenting at Brest University Hospital in Brest, France, with clinically suspected PE and positive d-dimer or high clinical probability. Patients in whom VTE was deemed absent were not given anticoagulants and were followed up for 3 months. RESULTS: Detection of DVT by ultrasonography established the diagnosis of PE in 43 (13%). Lung scan associated with clinical probability was diagnostic in 243 (76%) of the remaining patients. MDCT scan was required in only 35 (11%) of the patients. The 3-month thromboembolic risk in patients not given anticoagulants, based on the results of the diagnostic protocol, was 0.53% (95% CI, 0.09-2.94). CONCLUSIONS: A diagnostic strategy combining clinical assessment, d-dimer, ultrasonography, and lung scan gave a noninvasive diagnosis in the majority of outpatients with suspected PE and appeared to be safe