Contributors:É. Maury, C. Pichereau, S. Bourcier, A. Galbois, G. Lejour, J.-L. Baudel, H. Ait-Oufella, B. Guidet
Le poumon a longtemps était considéré comme inaccessible aux ultrasons. Cependant, des travaux cliniques récents montrent que cet organe peut être exploré par l’échographie. L’échographie pleuropulmonaire apparaît même dans certaines indications supérieures à la radiographie thoracique. Cette exploration ne nécessite pas d’équipement spécifique. La recherche d’un pneumothorax au moyen de l’échographie est possible en utilisant une combinaison de signes qualitatifs simples : existence d’un glissement pleural, présence de lignes B, existence d’un point poumon. Le glissement pleural correspond à l’artefact produit par le glissement des deux feuillets pleuraux l’un contre l’autre. Les lignes B traduisent l’existence d’un syndrome interstitiel. La présence du glissement pleural et/ou l’existence de lignes B ont une valeur prédictive négative de 100 % et éliminent formellement un pneumothorax à l’endroit où est appliquée la sonde. La présence d’un point poumon est pathognomonique du pneumothorax mais sa sensibilité n’est que de 60 %. L’échographie est donc un moyen simple permettant d’exclure rapidement un pneumothorax (présence du glissement pleural ou de lignes B) et d’affirmer à l’inverse un pneumothorax quand un point poumon est observé. La question qui reste posée est de savoir si l’échographie pourrait totalement se substituer à la radiographie thoracique dans la prise en charge de cette pathologie.
Contributors:Lisette J.M.E. van der Does, Charles Kik, Ad J.J.C. Bogers, Maurits A. Allessie, Natasja M.S. de Groot
Focal waves appear frequently at the epicardium during persistent atrial fibrillation (AF), however, the origin of these waves is under debate. We performed simultaneous endo-epicardial mapping of the right atrial wall during longstanding persistent AF in a patient undergoing cardiac surgery. During 10 seconds 53 and 59 focal waves appeared at random at respectively the endocardium and epicardium. Repetitive focal activity did not last longer than 3 cycles. Transmural asynchrony and conduction might be the origin of focal waves. Asynchronous propagation of fibrillation waves in 3 dimensions would stabilize the arrhythmia and could explain the limited success of persistent AF ablation.
The tectonic and topographic evolution of southeast Asia is attributed to the indentation of India into Eurasia, gravitational collapse of the uplifted terrains and the dynamics of the Sunda and other western Pacific subduction zones, but their relative contributions remain elusive. Here, we analyse 3D numerical geodynamic modelling results involving a collision-subduction system and show that vigorous asthenospheric flow due to differential along-strike slab kinematics may contribute to the surface strain and elevations at collision-subduction transition zones. We argue that protracted northward migration of the collisional front and Indian slab during south to south-westward rollback subduction along the Sunda margin might have produced a similar asthenospheric flow. This flow could have contributed to the southeast Asia extrusion tectonics and uplift of the terrains around the eastern Himalayan syntaxis and protruding from southeast Tibet. Therefore, we suggest that the tectonics and topographic growth east and southeast of Tibet are controlled not only by crustal and lithospheric deformation but also by asthenospheric dynamics.
Contributors:Chang Song, James D. Nicholson, Sarah M. Clark, Xin Li, Achsah D. Keegan, Leonardo H. Tonelli
The concept of the brain as an immune privileged organ is rapidly evolving in light of new findings outlining the sophisticated relationship between the central nervous and the immune systems. The role of T cells in brain development and function, as well as modulation of behavior has been demonstrated by an increasing number of studies. Moreover, recent studies have redefined the existence of a brain lymphatic system and the presence of T cells in specific brain structures, such as the meninges and choroid plexus. Nevertheless, much information is needed to further the understanding of brain T cells and their relationship with the central nervous system under non-inflammatory conditions. In the present study we employed the Rag2−/− mouse model of lymphocyte deficiency and reconstitution by adoptive transfer to study the temporal and anatomical expansion of T cells in the brain under homeostatic conditions. Lymphopenic Rag2−/− mice were reconstituted with 10 million lymphoid cells and studied at one, two and four weeks after transfer. Moreover, lymphoid cells and purified CD4+ and CD8+ T cells from transgenic GFP expressing mice were used to define the neuroanatomical localization of transferred cells. T cell numbers were very low in the brain of reconstituted mice up to one week after transfer and significantly increased by 2weeks, reaching wild type values at 4weeks after transfer. CD4+ T cells were the most abundant lymphocyte subtype found in the brain followed by CD8+ T cells and lastly B cells. Furthermore, proliferation studies showed that CD4+ T cells expand more rapidly than CD8+ T cells. Lymphoid cells localize abundantly in meningeal structures, choroid plexus, and circumventricular organs. Lymphocytes were also found in vascular and perivascular spaces and in the brain parenchyma across several regions of the brain, in particular in structures rich in white matter content. These results provide proof of concept that the brain meningeal system, as well as vascular and perivascular spaces, are homing sites of lymphocytes and suggest the possibility of a brain specific T cell subtype.