1,720,981 research outputs found
Description of the resistome and search for new antimicrobial compounds in new bacterial species isolated from the human microbiota
No full textLes réseaux de surveillance épidémiologiques rapportent une augmentation des bactéries multi-résistantes aux antibiotiques alors que les industries pharmaceutiques abandonnent la recherche de nouveaux composés antimicrobiens. Cet abandon est initialement dû à l’échec d’identification de nouveaux antibiotiques ainsi qu’à la redécouverte de molécules déjà connues.Au sein de l’Institut Hospitalo-Universitaire Méditerranée Infection, un grand nombre de nouvelles espèces bactériennes isolées du microbiote humain a été découvert par une technique innovante de culture appelée « culturomique ». Cette thèse se divise donc en deux axes principaux qui sont premièrement la recherche de nouvelles substances antimicrobiennes, deuxièmement l’évaluation du réservoir de gènes de résistance nouveaux et/ou connus dans ces populations bactériennes. Dans un premier temps, nous avons réalisé une revue de la littérature sur les différentes stratégies in silico et in vitro ayant permis l’identification de nouveaux composés antimicrobiens . Puis, nous avons, par des analyses in silico, recherché des bactéries sécrétrices de nouveaux antibiotiques.Dans le second axe , nous nous sommes intéressés en premier lieu à la résistance à la fosfomycine. Cet antibiotique fait partie des « vieux antibiotiques ». Nous avons donc évalué la résistance à la fosfomycine de 25 nouvelles espèces bactériennes. Pour trois bactéries dont la Concentration Minimale Inhibitrice (CMI) est la plus élevée, nous avons recherché les gènes responsables . Enfin, nous avons fait une description de la prévalence des différents gènes de résistance au sein de 335 nouvelles espèces bactériennes.Epidemiological surveillance networks report an increase in Multi-Drug Resistant bacteria as the pharmaceutical companies have abandoned the search for new antimicrobial compounds. This abandonment was initially due to the failure to identify new antibiotics and the rediscovery of already known molecules. Thus, the discovery of new bacterial species always represents a hope for the identification of new antibiotics but also allows us to characterise the reservoir of unknown resistance genes.At the Institut Hospitalo-Universitaire Méditerranée Infection, new bacterial species isolated from the human microbiota have been discovered by innovative culture techniques called "culturomics". This thesis is therefore divided into two mains parts: i) the search for new antimicrobial substances and ii) the evaluation of the reservoir of new and known resistance genes in these bacterial populations.Firstly, we carried out a literature review on the different strategies that have enabled the identification of new antimicrobial compounds. Then, through in silico analyses, we searched for bacteria secreting new antibiotics with a particular interest in NRP and PK. In the second part of this thesis, we firstly focus on fosfomycin resistance. This antibiotic is one of the “old antibiotics” which reintroduction for the treatment of multidrug-resistant infections is being considered. Finally, we described the prevalence of the different resistance genes in 335 new bacterial species. As a result of this analysis, in silico analyses revealed new variants of resistance genes, but also evidence of exchanges of resistance genes between the human microbiota and human pathogenic bacteria
Role of bacteria in obesity : iimplication of Lactobacillus sp. genomes in weight gain
No full textIl a été montré que la consommation de Lactobacillus pouvait avoir des conséquences sur le poids de l’hôte, et ce, en fonction de la souche inoculée. Nous avons voulu comprendre le mécanisme par lequel ces microorganismes prolifèrent dans le tube digestif et induisent un changement de poids. Nous avons exploré la production de bactériocines permettant aux souches de Lactobacillus de croître au détriment des autres micro-organismes. Nous avons constitué une base de données de bactériocines nommée BUR et recherché les bactériocines dans les génomes de bactéries du tube digestif humain. Nous avons observé une abondance de bactériocines dans les génomes des bactéries du tube digestif, majoritairement dans les Firmicutes. Aussi, nous avons approfondi l’étude du profil métabolique des souches de Lactobacillus par une approche génomique et dans une analyse in vitro. Nous avons constaté que les souches de Lactobacillus dont la consommation induit une perte de poids possèdent des enzymes qui empêchent l'obésité en réduisant les niveaux de glucose dans le sang, les niveaux de triacylglycérols sériques, la masse corporelle et l'accumulation de graisse, tandis que les génomes des souches dont la consommation induit un gain de poids codent pour plusieurs enzymes favorisant la production de fructose, et mobilisent l'énergie et le carbone stocké dans les acides gras. De ce fait, nous pouvons dire que les espèces de Lactobacillus jouent un rôle important dans la digestion des nutriments, avec un effet direct sur le changement de poids.It has been shown that Lactobacillus consumption could affect the weight of the host, and led consequently to significant weight gain or loss, depending on the strain. We wanted to understand the mechanism by which these microorganisms induce weight change. We explored the various known mechanisms, including the production of bacteriocins, allowing Lactobacillus strains to grow at the expense of other microorganisms. We established a bacteriocin database, named BUR, and search for bacteriocins in the genomes of human gut bacteria. We observed an abundance of bacteriocins in the genomes of bacteria in the digestive tract, predominantly in Firmicutes. We also have deepened the study of the metabolic profile of Lactobacillus strains, both by a genomic approach and in an in vitro assay, to better understand the pathophysiology of obesity. We have found that Lactobacillus strains whose consumption induces weight loss possess enzymes which prevent obesity by reducing glucose levels in blood, serum triacylglycerols levels, body weight and the accumulation of fat, whereas the genomes of strains whose consumption leads to weight gain encode several enzymes promoting the production of fructose and mobilize energy and the carbon stored in the fatty acids. Therefore, we can say that Lactobacillus species are important in the digestion of nutrients and can have a great influence on carbohydrate and lipid metabolism, with direct effect on weight change
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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