Variability of extracellular vesicle release during storage of red blood cell concentrates is associated with differential membrane alterations, including loss of cholesterol-enriched domains

Transfusion of red blood cell concentrates is the most common medical procedure to treat anaemia. However, their storage is associated with development of storage lesions, including the release of extracellular vesicles. These vesicles affect in vivo viability and functionality of transfused red blood cells and appear responsible for adverse post-transfusional complications. However, the biogenesis and release mechanisms are not fully understood. We here addressed this issue by comparing the kinetics and extents of extracellular vesicle release as well as red blood cell metabolic, oxidative and membrane alterations upon storage in 38 concentrates. We showed that extracellular vesicle abundance increased exponentially during storage. The 38 concentrates contained on average 7 × 1012 extracellular vesicles at 6 weeks (w) but displayed a ∼40-fold variability. These concentrates were subsequently classified into 3 cohorts based on their vesiculation rate. The variability in extracellular vesicle release was not associated with a differential red blood cell ATP content or with increased oxidative stress (in the form of reactive oxygen species, methaemoglobin and band3 integrity) but rather with red blood cell membrane modifications, i.e., cytoskeleton membrane occupancy, lateral heterogeneity in lipid domains and transversal asymmetry. Indeed, no changes were noticed in the low vesiculation group until 6w while the medium and the high vesiculation groups exhibited a decrease in spectrin membrane occupancy between 3 and 6w and an increase of sphingomyelin-enriched domain abundance from 5w and of phosphatidylserine surface exposure from 8w. Moreover, each vesiculation group showed a decrease of cholesterol-enriched domains associated with a cholesterol content increase in extracellular vesicles but at different storage time points. This observation suggested that cholesterol-enriched domains could represent a starting point for vesiculation. Altogether, our data reveal for the first time that the differential extent of extracellular vesicle release in red blood cell concentrates did not simply result from preparation method, storage conditions or technical issues but was linked to membrane alterations

« Muntus, caciques et colons : le travail épique à l’œuvre dans Changó el gran putas et Rhapsodie pour Hispaniola »

International audienc

« Muntus, caciques et colons : le travail épique à l’œuvre dans Changó el gran putas et Rhapsodie pour Hispaniola »

International audienc

Construire le mythe pour se réapproprier l’histoire : la figure de Mackandal dans quelques oeuvres caribéennes

Esclave révolté exécuté en Haïti en 1758, François Mackandal bascule rapidement des archives à la fiction. En confrontant les textes de Moreau de Saint-Méry et du Mercure de France à ceux d’Alejo Carpentier, d’Édouard Glissant et de Manuel Rueda, on se propose de montrer comment, en faisant basculer ce héros des soulèvements prérévolutionnaires haïtiens de la légende au mythe, des écrivains proposent un nouveau point de vue sur l’histoire en valorisant le rôle des esclaves dans leur libération

Makandal's metamorfosis : heroism and identities in caribbean literature

Cette thèse s’intéresse à l’ensemble des réécritures portant sur le personnage de Makandal, esclave insurgé, exécuté en 1754 à Saint-Domingue, dont la légende raconte qu’il aurait échappé aux flammes grâce à ses pouvoirs de métamorphose. La recherche interroge les mécanismes de fabrication de la figure en montrant que celle-ci se construit à travers ses circulations transatlantiques, qui s’accompagnent, dans la période postcoloniale, d’un renversement axiologique : de criminel, Makandal devient guerrier libérateur. Son émergence en tant que héros est replacée dans le processus de (ré)élaboration des identités nationales caribéennes post-indépendances, la littérature se faisant l’écho et le vecteur d’une concurrence mémorielle qui passe par la mise en avant de figures historiques européennes puis amérindiennes au détriment des figures afrodescendantes, qui demeurent invisibles ou occultées. À partir d’une réflexion théorique sur la notion de « héros culturel » et de la remodélisation d’un système héroïque global et dynamique, on postulera que la figure de Makandal permet de penser un type d’héroïsme dissident se caractérisant par sa nature de contrepoint face au héros national. Ses éternelles métamorphoses lui confèrent une dimension allégorique substituant à l’assignation identitaire nationale essentialiste une identité diasporique hybride, toujours en tension.This thesis examines all the rewritings concerning Makandal, an insurgent slave, executed in 1754 in Santo Domingo, whose legend claims he escaped the flames thanks to his powers of metamorphosis. It questions the figure's fabrication, showing that it is constructed by a permanent movement of transatlantic circulations – a process which is accompanied, in the postcolonial period, by an axiological reversal: from a criminal, Makandal becomes a liberating warrior. His emergence as a hero is placed in the process of the (re)elaboration of post-independence Caribbean national identities. Literature is indeed the place of a memorial competition, in which the successive highlighting of European and, then, Native-American historical figures was done to the detriment of Afro-descendant figures, who remain invisible or hidden. Based on a theoretical reflection concerning the notion of « cultural hero » and the remodeling of a global and dynamic heroic system, it will be postulated that the figure of Makandal makes it possible to define a form of dissident heroism, characterized by the counterfigure position he occupies in front of the national hero. Its eternal metamorphoses give it an allegorical dimension, substituting the assignment of essentialist national identity with a hybrid diasporic identity always in tension