1,721,009 research outputs found
Fonction et métabolisme des plaquettes au cours de la COVID-19
No full textCette thèse porte sur le rôle de l'activation et de la réactivité plaquettaire chez les patients atteints de COVID-19 (Coronavirus disease 2019), à la lumière de l'hypercoagulabilité observée dans la maladie. Les études menées au cours de cette thèse révèlent que les patients atteints de COVID-19 ont un profil d'activation différent selon la phase de la pandémie étudiée, une réactivité plaquettaire altérée, associée à une modification de leur lipidome, métabolome, transcriptome, et une profonde dysfonction mitochondriale. La première étude, réalisée avec des patients hospitalisés pour COVID-19 et des volontaires sains pendant la première vague de la pandémie, montre la présence de plaquettes hyperactivées, la formation accrue de complexes plaquettes-neutrophiles, et la perturbation de la signalisation Glycoproteine (GP)VI, un récepteur plaquettaire impliqué dans l'initiation de la formation du clou plaquettaire. La seconde étude examine en profondeur la fonction mitochondriale et le statut métabolique des plaquettes, révélant un dysfonctionnement mitochondrial, une défaillance bioénergétique globale, un stress oxydatif accru associé à un phénotype plaquettaire prothrombotique. La troisième étude examine le lipidome plaquettaire chez les mêmes patients et identifie des altérations significatives dans la composition des lipides plaquettaires, suggérant une association entre la réactivité plaquettaire et leur composition en lipides. L'ensemble de ces résultats permet de mieux comprendre la physiopathologie de l'hypercoagulabilité liée à la COVID-19, en mettant en évidence une dysfonction des plaquettes, une altération de la composition lipidique et un dysfonctionnement mitochondrial et métabolique. Ces études offrent des pistes de recherche potentielles pour comprendre la physiopathologie plaquettaire dans d'autres maladies infectieuses.This thesis focuses on the role of platelet activation and reactivity in COVID-19 (Coronavirus disease 2019) patients, exploring its contribution to the hypercoagulability observed in the disease. The studies conducted during this thesis reveal that COVID-19 patients have a different activation pattern depending on the phase of the pandemic, an altered platelet reactivity, associated with a modification of their lipidome, metabolome, transcriptome, and a strong mitochondrial dysfunction. The first study, performed on COVID-19 hospitalized patients and healthy volunteers during the first wave of the pandemic, shows the presence of hyperactivated platelets, increased formation of platelet-neutrophil complexes, and disruption of glycoprotein VI signaling, a platelet receptor involved in the initiation of platelet plug formation. The second study takes an in-depth look at mitochondrial function and metabolic status of platelets, revealing mitochondrial dysfunction, bioenergetic failure, global metabolic shutdown, increased oxidative stress, and a prothrombotic platelet phenotype. The third study examines the platelet lipidome in patients and controls and identifies significant alterations in platelet lipid composition, suggesting an association between platelet reactivity and lipid composition. Taken together, these results provide insight into the pathophysiology of COVID-19-related hypercoagulability, demonstrating platelet hyperactivation, altered platelet lipid composition, and mitochondrial and metabolic dysfunction. These studies suggest that platelet dysfunction may contribute to the thromboembolic complications observed in COVID-19 disease, and they can guide future research for understanding platelet pathophysiology in other diseases and infectious conditions
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
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
Coagulation in patients with severe sepsis
No full textIn the majority of patients with severe sepsis, systemic activation of coagulation is present. Increasing evidence points to an extensive cross-talk between coagulation and inflammation that may play an important role in the pathogenesis of sepsis. Inflammation not only leads to activation of coagulation, but coagulation also considerably affects inflammatory activity. Molecular pathways that contribute to inflammation-induced activation of coagulation have been precisely identified. Proinflammatory cytokines and other mediators are capable of activating the coagulation system and downregulating important physiological anticoagulant pathways. Activation of the coagulation system and ensuing thrombin generation is dependent on expression of tissue factor on activated mononuclear cells and endothelial cells, and is insufficiently counteracted by TFPI. Simultaneously, endothelial-bound anticoagulant mechanism, in particular the protein C system, is shutoff by proinflammatory cytokines. In addition, fibrin removal is severely inhibited, because of inactivation of the fibrinolytic system, caused by an upregulation of its main inhibitor, plasminogen activator inhibitor type 1 (PAI-1). Increased fibrin formation and impaired removal lead to (micro)vascular thrombosis, which may result in tissue ischemia and subsequent organ damage. The cornerstone of the management of coagulation in sepsis is the specific and vigorous treatment of the underlying disorder. Strategies aimed at the inhibition of coagulation activation may theoretically be justified and have been found beneficial in experimental and initial clinical studies. Heparin may be an effective anticoagulant approach and alternative strategies comprise restoration of physiological anticoagulant pathway
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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