1,721,054 research outputs found
Use of a LightCycler gyrA mutation assay for identification of ciprofloxacin-resistant Campylobacter coli
No full textA fluorescence resonance energy transfer-based assay has been employed to detect mutations at the 86 codon in the DNA gyrase A (gyrA) gene in Campylobacter coli strains. These mutations were associated with ciprofloxacin resistance in strains isolated in Italy in 2000. The mutations in the gyrA gene were detected by real-time PCR amplification followed by hybridization with two fluorescent probes designed with sequences complementary to the wild-type C. coli gyrA gene. Mutation detection was performed by melting peak analysis of the probe-PCR product hybrid performed on a LightCycler (Roche Diagnostic). This gyrA mutation assay allows a rapid and reproducible screening method of ciprofloxacin-resistant C. coli strains. © 2002 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved
Identification of ciprofloxacin-resistant Campylobacter jejuni and analysis of the gyrA gene by the LightCycler mutation assay
No full textA real-time PCR assay was developed to identify ciprofloxacin-resistant Campylobacter jejuni. Ciprofloxacin resistance in C. jejuni has been associated with a C→T nucleotide point mutation occurring at the 86 codon of the gyrA gene. Other nucleotide substitutions have been identified in proximity to or at the same codon in the gyrA gene, but their role in ciprofloxacin resistance is still unknown. The LightCycler assay is based on the fluorescence resonance energy transfer technology using melting peak analysis of two fluorescent probes hybridized on PCR amplicons. This assay was used to detect the 86-codon mutation conferring ciprofloxacin resistance, as well as other nucleotides substitutions occurring within the same site in the gyrA gene. This gyrA mutation assay allows a rapid and reproducible screening method of ciprofloxacin resistant strains and was applied to C. jejuni strains isolated in Italy in 2000. © 2004 Elsevier Ltd. All rights reserved
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
Cytotoxin-associated gene A and vacuolating cytotoxin A in human isolates of Helicobacter pylori and their association with the clinical status of ulcer disease
No full textOBJECTIVE:
The aim of this study was to evaluate whether different Helicobacter pylori genotypes are associated with different clinical stages of peptic ulcer disease (PUD).
DESIGN:
We assessed the virulence characteristics of H. pylori isolates from patients with active PUD (presence of an ulcer crater at endoscopy) and from those with PUD in remission (normal endoscopic findings or scar not induced by drugs in PUD patients).
METHODS:
H. pylori isolates from biopsies of the gastric antrum were examined for cagA and vacA genotypes by PCR amplification and Western blot analysis. Descriptive statistical techniques and multivariate polytomous logistic regression were used to estimate adjusted odds ratio (OR) for cagA and vacA genotypes in patients with active PUD or PUD in remission. Patients with non-ulcer dyspepsia (NUD) were used as negative controls.
RESULTS:
The cagA genotype and phenotype were found to be differently associated with disease status. In fact, the multivariate regression model showed that gastric colonization by CagA+ H. pylori strains was associated with an increased risk of active PUD (OR 2.58), whereas the OR for patients with PUD in remission was 0.94.
CONCLUSIONS:
Our data indicate that the active ulcer status is more strongly associated with H. pylori strains carrying the pathogenicity island (PAI) than remission status. These results support the hypothesis that a dynamic equilibrium exists among bacterial populations with or without the PAI, and that the relapse of the peptic ulcer could be consequent to expansion of the H. pylori population carrying the PAI
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
Tetracycline and Streptomycin Resistance Genes, Transposons, and Plasmids in Salmonella enterica Isolates from Animals in Italy
No full textFifty-eight multidrug-resistant Salmonella enterica strains of 20 serotypes, isolated from animal sources in Italy, were analyzed for tet(A) and strA-strB, conferring tetracycline and streptomycin resistance, respectively. The strA and strB genes were highly prevalent in Salmonella strains of our collection, being detected in 84% of the streptomycin-resistant strains. In many strains, the strA and strB genes were linked to a particular Tn5393-derivative transposon characterized by the presence of the insertion sequence IS1133, previously identified only in the plant pathogen Erwinia amylovora. Sixty-eight percent of the tetracycline-resistant strains were tet(A) positive, indicating that this gene is widely diffused in Salmonella strains circulating in animals in Italy. Most of the tet(A) genes were localized within a deleted Tn1721 transposon variant. Two prevalent repN and repIl resistance plasmids were identified in Salmonella isolates of our collection
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