La sécurité alimentaire et nutritionnelle au Niger : l'identification des populations vulnérables

Conference given outside the academic context (2013)

La réception des hiéroglyphes égyptiens à la Renaissance et aux Temps modernes. La quête d'une écriture universelle

Scientific conference (2013, April 16)

The impact of negative (fear) and positive (pride) emotional appeals on persuasion in a public health communication context: road safety case in Belgium.

Conference given outside the academic context (2013)

Les enjeux du métier de conseiller en prévention

Conference given outside the academic context (2013)

Etat des lieux en 6000 signes

Scientific conference (2013, April 16)

La neuroinvasion dans les maladies à prions: étude de l'interface neuroimmune FDC - système nerveux sympathique

Doctoral thesis (2013)

Prion diseases are neurodegenerative diseases affecting the central nervous system (CNS) wherein the PrPd disease-associated prion infectious agent is an abnormal isoform of PrPc host-encoded cellular ... [more ▼]

Prion diseases are neurodegenerative diseases affecting the central nervous system (CNS) wherein the PrPd disease-associated prion infectious agent is an abnormal isoform of PrPc host-encoded cellular prion protein. The process through which the prion infectious agent is transferred to the CNS, the neuroinvasion, is still unknown, but secondary lymphoid organs seem to play an important role in prion amplification prior the invasion of the associated peripheral nervous system (PNS). In particular, modifications of follicular dendritic cells (FDC) and sympathetic nervous system (SNS) of lymphoid organs could influence the speed of neuroinvasion, and thus the length of the disease incubation period. It was shown that the lack of mature FDC prevents the replication of the infectious agent in secondary lymphoid organs. Likewise, sympathectomy delays the onset of the disease, and enhances sympathetic innervation reduces the incubation period. In mice, the relative positioning of FDC and sympathetic neural fibres plays a role in the incubation period following scrapie inoculation. This study thus focuses on the neuroimmune interface between FDC and sympathetic neural fibres. First, the number of close interactions between FDC and sympathetic neural fibres of five mouse strains with the same Prnpa genotype was estimated to check if it could explain the different incubation period observed after inoculation of primary bovine spongiform encephalopathy (BSE) infected-brain. Then we checked if scrapie infection, by oral or intraperitoneal route, could influence this neuroimmune interface between FDC and sympathetic neural fibres within Peyer’s patches (PP) and spleen of the C57BL/6 mouse strain. In the first part of this work, co-localizations between FDC and sympathetic neural fibres were observed in vivo within germinal centers (GC) of mouse spleen. Among the five mouse strains exhibiting the same Prnpa genotype, three strains (RIII-1, RIII-2 and 129/Ola) showed an incubation period about 100 days shorter than those of C57BL and C57BL/6 mouse strains when inoculated with primary BSE. Moreover, amplification by FDC seems an obligatory process before subsequent neuroinvasion as an intracerebral inoculation doesn’t reduce the incubation period observed with an intraperitoneal inoculation. A meticulous analysis revealed that the density of close interactions between FDC and sympathetic neural fibres is not higher for the three mouse strains with a shorter incubation period. However, these three mouse strains with a shorter incubation period after primary BSE inoculation have a higher proportion of FDC networks with close interactions than the mouse strains with a longer incubation period. These results suggest that it is not the quantity of sympathetic neural fibres close to FDC, but rather the percentage of FDC with close sympathetic neural endings that could influence the incubation period of prions diseases. In the second part of this work, it came out that prion infection did not result in neuronal loss within the PNS like observed in the CNS, and also did not modify the FDC-SNS neuroimmune interface of secondary lymphoid organs where PrPd deposits are observed within germinal centers. For a single mouse strain orally infected with scrapie, neither FDC networks hypertrophy nor sympathetic neural fibres closer than 10 μm from a FDC network were observed within GC of PP. Moreover, in our conditions, the prion strain did not seem to alter the neuroimmune interface between FDC and SNS in PP that could explain the different incubation periods observed with the 139A and ME7 scrapie strains. To check if prion infection does not modify the FDC-SNS neuroimmune interface, close interactions between FDC and sympathetic neural fibres already shown in the spleen were analyzed in the same mouse strain intraperitoneally infected with the 139A scrapie strain. In that case as well, no differences were observed in FDC network hypertrophy, in the in vivo density of sympathetic neural fibres closer than 10 μm from a FDC network, or in the proportion of well innervated FDC networks, compared to control mice. An in vitro model of coculture of splenic FDC from the same C57BL/6 mouse strain with nerve cells from dorsal root ganglia (DRG) also yielded similar results. FDC isolated from scrapie 139A infected mice exhibited the same neuritogenic or neurotrophic effects than FDC isolated from control mice. During these experiments, it was also noted that young-adult or middle-age mice showed both the same mean density of close interactions between FDC and SNS. However, with age, even if the splenic volume occupied by FDC networks halved, the proportion of FDC networks with close interactions almost doubled. It would be very interesting to check this last parameter in old mice that show some delay in neuroinvasion of prion disease but also to evaluate if this percentage of well innervated FDC network contributes to the prion pathogenesis within the spleen. In conclusion, scrapie 139A and ME7 strains don’t modify FDC-SNS neuroimmune interface of secondary lymphoid organs, not allowing explaining the different incubation period observed with equivalent infectious doses. Moreover, following an oral inoculation of prion, neuroinvasion within PP would not involve direct contact between FDC and sympathetic nerves, but rather another process still to be determined or implying other nerve fibres and/or mobile cells such as macrophages or dendritic cells. However, in the spleen, the percentage of FDC networks with close sympathetic neural fibres – rather than the number of sympathetic neural fibres close to the FDC network – observed for a given age, species and Prnp genotype at the time of inoculation could play a role in the different incubation periods observed for the same prion strain. The cellular compounds involved in the specific FDC microenvironment still have to be determined for each cell implied in the neuroinvasion process. [less ▲]

In situ nitroxide-mediated polymerization of styrene promoted by the N-tert-butyl-alpha-isopropylnitrone/BPO pair: ESR investigations

in Journal of Polymer Science. Part A-1, Polymer Chemistry (2013), 51(8), 1786-1795

The styrene polymerization initiated by benzoyl peroxide (BPO) in the presence of N-tert-butyl--isopropylnitrone as nitroxide precursor is well-controlled provided that a prereaction between the nitrone ... [more ▼]

The styrene polymerization initiated by benzoyl peroxide (BPO) in the presence of N-tert-butyl--isopropylnitrone as nitroxide precursor is well-controlled provided that a prereaction between the nitrone and BPO is carried out in suitable conditions prior to polymerization at a higher temperature. Electron spin resonance (ESR) spectroscopy was implemented to probe the nitroxides formed during both steps, that is, the prereaction and polymerization, and to get crucial information regarding the structure of the nitroxides responsible for the polymerization control. ESR studies combined with first principles calculations have evidenced that nitroxides observed during the prereaction in the presence of styrene and during the polymerization steps consist of a mixture of two macronitroxides. One is formed by the addition of a growing polystyrene chain to the nitrone as would be expected. However, the second one results from the addition of a polystyrene chain to tert-butyl nitroso that is in situ formed presumably by decomposition of the first macronitroxide type. [less ▲]

Quel sort pour les déchets moyennement et hautement radioactifs belges ? Controverse sur le choix de l’option.

Conference (2013, April 15)

Pour saisir les ressorts de la problématique de la gestion des déchets moyennent et hautement radioactifs et/ou de longue durée de vie (déchets de catégorie B&C), cet article met en évidence, dans un ... [more ▼]

Pour saisir les ressorts de la problématique de la gestion des déchets moyennent et hautement radioactifs et/ou de longue durée de vie (déchets de catégorie B&C), cet article met en évidence, dans un premier temps, la transformation du mode de prise de décision entourant la gestion des déchets nucléaires belges. Le passage d’un mode de décision technocratique à un mode davantage participatif révèle la présence de nouveaux acteurs dans le jeu décisionnel légal avec notamment, l’obligation de s’intéresser à l’acceptabilité sociale du projet de gestion. Dans ce contexte, les chercheurs interrogent également le rôle des médias dans cette mise en politique et plus précisément le cadrage que les journalistes apportent à la problématique. Aussi, les cadrages différemment posés par le journaliste francophone et le journaliste néerlandophone du plan de gestion des déchets B&C (appelé Plan Déchets) impliquent une mobilisation d’acteurs différents et une mise en débat de la problématique différente. Au-delà des enjeux propres à chaque acteur, nous verrons également, à l’identique de Barthe (2010), que les différentes options technologiques (autrement dit, les réponses proposées pour gérer les déchets) suggèrent des traitements de l’incertitude en tous points opposés et engagent des temporalités décisionnelles très différentes. Ces acteurs de la scène médiatique belge sont-ils ceux qui sont nouvellement intégrés dans la mise en politique? Les débats sont-ils identiques? Quel est le rôle des journalistes dans le processus décisionnel ? [less ▲]

Utilisation du système CardioPAT® en postopératoire de chirurgie cardiaque

Report (2013)

La mortalité de l'abeille domestique : entre communication médiatique et scientifique

Conference given outside the academic context (2013)

A l’heure actuelle, plus personne n’ignore que nos populations d’abeilles domestiques subissent de lourdes pertes, chez nous comme dans de nombreux autres pays. Les médias ont axés leur communication sur ... [more ▼]

A l’heure actuelle, plus personne n’ignore que nos populations d’abeilles domestiques subissent de lourdes pertes, chez nous comme dans de nombreux autres pays. Les médias ont axés leur communication sur des messages très simples. On en retient surtout que les pesticides tuent nos abeilles. La conclusion au problème est dès lors évidente : il faut interdire les pesticides. Mais cette problématique est-elle si simple ? Ce message est-il le même que celui communiqué par les scientifiques ? Cette conférence permettra de faire le point sur les pertes en colonies d’abeilles domestiques. On s’intéressera plus particulièrement aux pertes de ces dernières années en Belgique, cartes et chiffres à l’appui. On y verra aussi comment chacun, qu’il soit citoyen, apiculteur, agriculteur,… peut aider à enrayer cette mortalité effrayante. [less ▲]