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Comparaison des performances de la scintigraphie aux leucocytes marqués et de la tomographie par émission de positons au 18F-FDG dans le diagnostic des infections de prothèses vasculaires : étude prospective menée au CHU de Bordeaux portant sur 34 patients inclus sur une période de 3 ans
No full textIntroduction: prosthetic vascular graft infections (PVGI) are associated with high mortality rates. The diagnosis is often difficult, especially in latent infections. To improve the outcome of the medical and surgical treatment, an early and definite diagnosis is critical, and actual diagnosis criteria are often insufficient. The present study compared the accuracy of positron emission tomography/computed tomography with 18F-fludeoxyglucose (18F-FDG PET/CT) and radiolabeled leucocyte scintigraphy single-photon emission computed tomography (SPECT) for the diagnosis of PVGI. Methods: we conducted a prospective monocentric study on patients undergoing scintigraphy and 18F-FDG PET/CT for a suspected PVGI between April 2013 and June 2016 at the Bordeaux University Hospital, France. Patients with thoracic aortic grafts were excluded. Diagnosis of PVGI was assessed by the Fitzgerald’s criteria at the end of the follow-up. Accuracy of both examinations was compared for every graft of each patient, using receiver-operating characteristic (ROC) curve analysis. We also compared the accuracy of three different visual scales for 18F-FDG PET/CT interpretation. Images were independently interpreted by two different nuclear medicine physicians blinded to patients clinical and other imaging data. Results : thirty-four patients were included, 14 had PVGI. An antibiotic treatment was started before nuclear imaging for 14 patients, including eight patients with a PVGI which was confirmed later. Ninety-three grafts were analyzed, 18 were infected. Regarding the three evaluated visual scales, our local scale had a better accuracy than two other ones (ROC areas under the curve [AUC] = 0.871, 0.76 and 0.777, respectively, p = 0.04 and 0.7). Applied on all grafts, accuracy of scintigraphy was significantly higher than PET/CT (ROC AUC = 0.904, CI 95% [0.823-0.985], and 0.871, CI 95% [0.786-0.955], respectively, p = 0.022). Accuracy of scintigraphy was not significantly different from PET/CT in thrombosed grafts (ROC AUC 0.983 and 0.903, respectively, p = 0.32). Inter-observer agreement was excellent for both examinations. Conclusion: this study highlighted a better accuracy of radiolabeled leucocyte scintigraphy compared to PET/CT for diagnosing PVGI, with an excellent inter-observer agreement.Introduction : le pronostic des IPV est grevé d’un taux de mortalité élevé. Un diagnostic fiable et précoce, souvent difficile en particulier dans les IPV latentes, est un pré-requis indispensable à l’amélioration de la prise en charge thérapeutique de ces infections. Notre étude a comparé, chez des patients suspects d’IPV, l’exactitude diagnostique de la 18F-FDG TEP et celle de la SLM au 99mTc, toutes deux couplées à la tomodensitométrie (TDM). Méthodes : étude prospective monocentrique menée au CHU de Bordeaux entre avril 2013 et juin 2016. Tous les patients adressés en médecine nucléaire pour une suspicion d’IPV sous-diaphragmatique étaient inclus. Le diagnostic d’IPV était établi à la fin du suivi selon les critères de Fitzgerald. L’exactitude diagnostique des deux examens a été comparée pour toutes les prothèses à partir de l’analyse de l’aire sous la courbe (ASC) des courbes ROC. Trois échelles visuelles différentes ont également été comparées pour l'interprétation de la 18F-FDG TEP, deux échelles précédemment publiées et une échelle élaborée dans le cadre de notre équipe pluridisciplinaire. Résultats : trente-quatre patients ont été inclus, 14 présentaient une IPV. Un traitement antibiotique a été débuté avant les examens d’imagerie nucléaire chez 14 patients, dont huit atteints d’IPV. Nous avons analysé 93 prothèses vasculaires, dont 18 infectées. En TEP, l’exactitude diagnostique de notre échelle semblait être supérieure aux deux autres (respectivement ASC ROC = 0,871, 0,76 et 0,777, p = 0,04 et 0,787), y compris dans le sous-groupe des prothèses thrombosées. L’exactitude diagnostique de la SLM était significativement supérieure à celle de la TEP (respectivement ASC ROC = 0,904, IC 95% [0,823-0,985] et 0,871 IC 95% [0,786-0,955], p = 0.022). Nous n’avons pas trouvé de différence significative dans le sous-groupe des prothèses thrombosées entre TEP et SLM. La reproductibilité inter-observateurs était excellente pour les deux examens. Les valeurs prédictives négatives de la TEP et de la SLM étaient excellentes, respectivement 98,5 % et 98,6%. Nous n’avons constaté aucun cas de faux négatif en TEP ou en SLM dans le sous-groupe des patients sous antibiotiques. Conclusion : l’exactitude diagnostique de la SLM est supérieure à celle de la TEP dans le diagnostic des IPV. Cette étude confirme les bonnes performances de la TEP et de la SLM dans le diagnostic de ces infections graves
Ex vivo and in vitro study of bacterial adhesion and biofilm formation on the surface of infected vascular grafts
No full textLes infections de prothèses et endoprothèses vasculaires (IPEV) sont des infections sévères, dont le pronostic est grevé d’une forte morbi-mortalité et d’un taux de rechute important.Ces échecs fréquents de traitement sont notamment liés à l’adhésion bactérienne sur le matériel vasculaire puis à la formation de biofilm permettant un échappement vis-à-vis du système immunitaire et au traitement antibiotique. Ce biofilm est mal caractérisé dans les IPEV et de nombreux principes du traitement sont déclinés du traitement des infections de prothèses ostéo-articulaires, malgré une physiopathologie très différente.Nous avons donc mené un projet tiré des questions qui découlent de notre activité clinique auprès de ces patients, de l’ex vivo à l’in vitro en étudiant Staphylococcus aureus, bactérie très fréquemment impliqué dans les IPV et associé à une forte production de biofilm.Toutes les prothèses vasculaires déposées au CHU de Bordeaux ont été recueillies d’une part pour imager le biofilm en microscopie électronique à balayage (MEB), d’autre part pour tenter d’améliorer le diagnostic microbiologique des IPEV. L’imagerie ex vivo des prothèses infectées a permis de visualiser une matrice très dense et adhérente de biofilm associée à de la fibrine, au sein de laquelle se logeaient les micro-organismes, dès un mois après le début de l’infection. Même la sonication ne permettait pas de complètement déloger biofilm et microorganismes de la surface de la prothèse. Aucune différence significative de conformation et de densité du biofilm, ni de quantité de microorganismes n’a été retrouvée entre les deux faces des prothèses. Ce caractère très dense du biofilm explique probablement l’importance de la dépose prothétique dans les IPEV.Le liquide de sonication d’une autre partie des prothèses déposées a été ensemencé dans des flacons d’hémocultures, ce qui a permis une accélération du délai de pousse pour certains patients et l’identification de microorganismes supplémentaires par rapport à la culture conventionnelle du liquide de sonication. Ces deux techniques pourraient être utilisées conjointement afin d’améliorer la sensibilité et le délai du diagnostic microbiologique de IPEV.Nous avons ensuite cherché à évaluer in vitro l’adhésion et la formation de biofilm par S. aureus à la surface de différents matériaux de prothèse vasculaire, du polyester recouvert de gélatine ou collagène plus ou moins associé à des substances anti-microbiennes, argent et triclosan. Trois souches de S. aureus ont été étudiées, une souche de référence formant du biofilm, et deux souches cliniques, une responsable d’IPEV et l’autre responsable de bactériémie sans infection de matériel. Plusieurs techniques ont pour cela été utilisées, afin d’évaluer les capacités d’adhésion et de formation de biofilm par coloration au crystal violet et test métabolique, la disposition et la conformation du biofilm en MEB, et la viabilité bactérienne à la surface des prothèses par culture après sonication. Les prothèses imprégnées d’argent et de triclosan ont montré une nette supériorité pour prévenir l’adhésion et la formation de biofilm par rapport à toutes les autres prothèses. Le revêtement en gélatine semblait mieux résister à la colonisation de S. aureus par rapport au collagène, et l’argent seul semblait paradoxalement favoriser la formation de biofilm, peut être un effet paradoxal lié à un effet inoculum. La phase très initiale de l’adhésion de S. aureus sur la surface des différentes prothèses vasculaires a quant à elle été évaluée par microscopie de force atomique et les résultats sont en cours d’analyse.Vascular graft and endograft infections (VGEIs) are severe infections, with a prognosis burdened by high morbidity and mortality rates and a significant recurrence rate. These frequent treatment failures are mainly attributed to bacterial adhesion on vascular materials and the subsequent formation of a biofilm that allows evasion from the immune system and antibiotic treatment. This biofilm is poorly characterized in VGEIs, and many treatment principles are adapted from bone and joint infections management, despite a very different pathophysiology.Therefore, we conducted a project based on questions arising from our clinical work, from ex vivo to in vitro studies involving Staphylococcus aureus, a bacterium frequently implicated in VGEIs and associated with high biofilm production. All vascular grafts removed at Bordeaux University Hospital were collected, firstly to visualize the biofilm using scanning electron microscopy (SEM) and secondly, to attempt to improve the microbiological diagnosis of VGEIs.Ex vivo imaging of infected grafts revealed a dense and adherent biofilm matrix associated with fibrin, within which microorganisms were embedded. Even sonication did not completely dislodge the biofilm and microorganisms from the grafts’ surface. No significant differences in biofilm conformation, density, nor microorganism quantity were found between the two sides of the grafts. This dense biofilm likely explains the importance of graft removal in VGEIs.The sonicate fluid from another portion of removed prostheses was inoculated into blood culture bottles, which accelerated the delay to positivity for some patients and identified additional microorganisms compared to conventional sonication fluid culture. These two techniques could be used together to improve the sensitivity and delay of the microbiological diagnosis of VGEIs.Next, we sought to evaluate in vitro the adhesion and biofilm formation by S. aureus on the surface of different vascular grafts materials, including polyester coated with gelatin or collagen, with or without antimicrobial substances such as silver and triclosan. Three strains of S. aureus were studied: a reference strain capable of biofilm formation, and two clinical strains, one responsible for VGEI and the other for a bloodstream infection without foreign material infection. Several techniques were used to assess adhesion and biofilm formation capacities, including crystal violet staining and metabolic testing, biofilm structure and conformation through SEM, and bacterial viability on the graft surface through sonicate fluid culture. Grafts impregnated with silver and triclosan showed clear superiority in preventing adhesion and biofilm formation compared to all other grafts. Gelatin coating appeared to better resist S. aureus colonization compared to collagen, and silver alone paradoxically seemed to promote biofilm formation, possibly due to an inoculum effect. The very initial phase of S. aureus adhesion to the surface of different vascular grafts was evaluated using atomic force microscopy, and the results are currently under analysis
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
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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