1,720,965 research outputs found
Shedding of genes that interfere with the pathogenic lifestyle: the Shigella model
No full textPathoadaptive mutations are evolutionary events leading to the silencing of specific anti-virulence loci. This reshapes the core genome of a novel pathogen, adapts it to the host and boosts its harmful potential. A paradigmatic case is the emergence of Shigella, the causative agent of bacillary dysentery, from its innocuous Escherichia coli ancestor. Here we summarize current views on how pathoadaptation has allowed Shigella to progressively increase its virulence. In this context, modification of the polyamine pattern emerges as a crucial step towards full expression of the virulence program in Shigella
RBANS: un valido strumento di valutazione cognitiva in soggetti HIV-infetti in cART = RBANS: a valid tool for cognitive assessment of HIV-infected people on cART
Full text linkIntroduction. Combination Antiretroviral Therapy (cART) has dramatically modified prognosis of individuals with HIV infection, and also the HIV-Associated Neurocognitive Disorders (HAND) spectrum, with reduction of the most severe form of HAND, HIV-Associated Dementia (HAD), but with persistence of the milder forms (ANI: Asymptomatic Neurocognitive Impairment; MND: Mild Neurocognitive Disorder). Screening of HAND requires efficient tools. The Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) is a tool that is fast and easy to use, and which is able to assess different cognitive domains. Our purpose is to evaluate the utility of RBANS in screening HAND.
Materials and methods. 95 HIV-infected patients (mean age 47.8 +/- 8.0, range 26-74 years; mean duration of infection 17.0 +/- 8.5, range 1-32 years) on cART, run by Internal Medicine, Allergology and Clinical Immunology, University of Cagliari, underwent neuropsychological assessment with MMSE, Clock Test and RBANS.
Results obtained were compared with participants in the RBANS validation study for the Italian population (control group). Results. Mean scores in MMSE and Clock Test were 29.3 +/- 1.3 and 8.5 +/- 1.4, respectively, indicative of normal cognitive abilities. In RBANS evaluation, however, the total index score was significantly lower than the mean of the control group (84.9 +/- 13.6, P < 0.001), as were indices of immediate memory (82.4 +/- 14.1), language (91.2 +/- 10), attention (87.9 +/- 16.1) and delayed memory (87.3 +/- 17.6).
Conclusions. Our results support the utility of RBANS for identification of HAND in HIV-infected people on cART
The Multifaceted Activity of the VirF Regulatory Protein in the Shigella Lifestyle
Full text linkShigella is a highly adapted human pathogen, mainly found in the developing world and causing a severe enteric syndrome. The highly sophisticated infectious strategy of Shigella banks on the capacity to invade the intestinal epithelial barrier and cause its inflammatory destruction. The cellular pathogenesis and clinical presentation of shigellosis are the sum of the complex action of a large number of bacterial virulence factors mainly located on a large virulence plasmid (pINV). The expression of pINV genes is controlled by multiple environmental stimuli through a regulatory cascade involving proteins and sRNAs encoded by both the pINV and the chromosome. The primary regulator of the virulence phenotype is VirF, a DNA-binding protein belonging to the AraC family of transcriptional regulators. The virF gene, located on the pINV, is expressed only within the host, mainly in response to the temperature transition occurring when the bacterium transits from the outer environment to the intestinal milieu. VirF then acts as anti-H-NS protein and directly activates the icsA and virB genes, triggering the full expression of the invasion program of Shigella. In this review we will focus on the structure of VirF, on its sophisticated regulation, and on its role as major player in the path leading from the non-invasive to the invasive phenotype of Shigella. We will address also the involvement of VirF in mechanisms aimed at withstanding adverse conditions inside the host, indicating that this protein is emerging as a global regulator whose action is not limited to virulence systems. Finally, we will discuss recent observations conferring VirF the potential of a novel antibacterial target for shigellosis
Molecular evolution of the nicotinic acid requirement within the Shigella/EIEC pathotype
No full textA multifactor regulatory circuit involving H-NS, VirF and an antisense RNA modulates transcription of the virulence gene icsA of Shigella flexneri.
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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
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