1,720,974 research outputs found
Réplication, dissémination et morphogenèse du virus de la maladie de Marek en cellules différenciées vers le lignage peau
No full textLe virus de la maladie de Marek (MDV) est un alpha-herpesvirus responsable de lymphomes T mortels chez la poule. La peau et en particulier le follicule plumeux est considéré comme le seul site de production de particules virales extracellulaires et est à l'origine de la dissémination horizontale du virus et de la contamination de l'environnement. Cependant, aucun système cellulaire ne permet de reproduire ce qui se passe dans ce tissu. Le but de ma thèse a donc ét de développer de nouveaux systèmes de culture permettant de reproduire la réplication, la morphogenèse et !'excrétion décrites in vivo. Pour cela, j'ai développé deux systèmes, des explants de peau d'embryons de poulet cultivés ex vivo et des kératinocytes obtenus par différenciation de cellules souches embryonnaires de poule. J'ai également montré la permissivité au MDV de ces deux modèles de peau puis y ai étudié la réplication et la morphogenèse virale. Ces modèles permettront la recherche des déterminants viraux et cellulaires impliqués dans la production de virions extracellulaires et leur dissémination
Replication, dissemination and morphogenesis of Marek's disease virus in differentiated cells of the dermo-epidermal lineage
No full textLe virus de la maladie de Marek (MDV) est un alpha-herpesvirus responsable de lymphomes T mortels chez la poule. La peau et en particulier le follicule plumeux est considéré comme le seul site de production de particules virales extracellulaires et est à l'origine de la dissémination horizontale du virus et de la contamination de l'environnement. Cependant, aucun système cellulaire ne permet de reproduire ce qui se passe dans ce tissu. Le but de ma thèse a donc été de développer de nouveaux systèmes de culture permettant de reproduire la réplication, la morphogenèse et l’excrétion décrites in vivo. Pour cela, j’ai développé deux systèmes, des explants de peau d’embryons de poulet cultivés ex vivo et des kératinocytes obtenus par différenciation de cellules souches embryonnaires de poule. J’ai également montré la permissivité au MDV de ces deux modèles de peau puis y ai étudié la réplication et la morphogénèse virale. Ces modèles permettront la recherche des déterminants viraux et cellulaires impliqués dans la production de virions extracellulaires et leur dissémination.Marek's disease (MD) is a highly contagious virus-induced lymphoma in chicken, caused by an alphaherpesvirus named Marek’s disease virus (MDV). The skin and especially, the feather follicle is the only tissue known to produce infectious cell-free virions and is responsible for the shedding of MDV into the environment and transmission between birds. However, no cell culture system actually reproduces this process ex vivo. Herein my thesis aim was to develop new culture systems to reproduce the efficient MDV replication, morphogenesis and shedding from the feather follicle. For that, I developed two systems, skin explants derived from embryos cultivated ex vivo and keratinocytes obtained by differentiation of chicken embryonic stem cells. I also showed that these two models were permissive to MDV infection and I studied in each one MDV replication and morphogenesis. These models will allow the search of viral and cellular determinants involved in the production of extracellular virions and shedding
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Marek's disease virus and skin interactions
No full textMarek's disease virus (MDV) is a highly contagious herpesvirus which induces T-cell lymphoma in the chicken. This virus is still spreading in flocks despite forty years of vaccination, with important economical losses worldwide. The feather follicles, which anchor feathers into the skin and allow their morphogenesis, are considered as the unique source of MDV excretion, causing environmental contamination and disease transmission. Epithelial cells from the feather follicles are the only known cells in which high levels of infectious mature virions have been observed by transmission electron microscopy and from which cell-free infectious virions have been purified. Finally, feathers harvested on animals and dust are today considered excellent materials to monitor vaccination, spread of pathogenic viruses, and environmental contamination. This article reviews the current knowledge on MDV-skin interactions and discusses new approaches that could solve important issues in the future
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Le virus de la maladie de Marek et ses interactions avec la peau
No full textNational audienceLe virus de la maladie de Marek (MDV) est un herpesvirus hautement contagieux, qui induit une immunosuppression et des lymphomes T chez la poule. Ce virus continue à circuler dans les élevages en dépit d’une vaccination largement pratiquée depuis 40 ans, avec un impact économique important au niveau mondial. Les follicules plumeux de la peau, qui permettent la genèse et l’ancrage des plumes, sont l’unique source d’excrétion connue du MDV dans le milieu extérieur. Ce tissu est à l’origine de la contamination de l’environnement et de la transmission du MDV entre oiseaux. Les cellules épithéliales des follicules plumeux sont les seules cellules identifiées produisant une grande quantité de virions infectieux matures, visibles par microscopie électronique à transmission et à partir desquelles des virions infectieux ont été purifiés. Enfin, les plumes prélevées sur les animaux ainsi que les poussières d’élevage sont aujourd’hui considérées comme d’excellents matériaux afin de suivre la vaccination, la circulation des virus pathogènes et la contamination de l’environnement. Cet article a pour objectif de résumer l’ensemble des connaissances actuelles sur l’interaction du MDV avec la peau et de proposer de nouvelles approches qui pourraient résoudre d’importantes questions biologiques relatives au MDV
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