1,721,082 research outputs found
Small RNAs targeting the 5' end of the viral polymerase gene segments specifically interfere with influenza type A virus replication
No full textHuman and avian influenza A viruses, associated with seasonal epidemics and occasionally with pandemics, have a high impact on public health. The development of new antivirals to counteract the emergence of drug resistant influenza virus variants is a main concern. The aim of this study was to develop systems for the efficient and stable expression of small therapeutic RNAs into influenza virus infected cells in order to get further insights on the efficacy of nucleic acid-based antiviral strategies. To this end, lentiviral vectors expressing either microRNAs or antisense-RNAs targeting the 5' end of the PA, PB1 and PB2 influenza virus genomic sequences were generated. Derivative recombinant lentiviral particles were employed to transduce the influenza virus highly susceptible human alveolar basal epithelial A549 cells. The expression of both RNA molecules led to a reduction up to 3 logs of the viral titer when transduced A549 cells were challenged with different human and avian subtypes of influenza type A virus. Importantly, no inhibition of influenza type B virus was observed. Overall our data support the development of nucleic acid-based antiviral strategies to control human and avian influenza A virus infection
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
Assessment of the risk of polyomavirus JC reactivation in patients with immune-mediated diseases during long-term treatment with infliximab
No full textPolyomavirus JC (JCV) reactivation causing progressive multifocal leukoencephalopathy is a main concern during biological therapies. Here, JCV reactivation in patients suffering from immune-mediated diseases after a long-term treatment with anti-tumor necrosis factor alpha (TNF-α) inhibitor infliximab was investigated. Peripheral mononuclear blood cells (PBMC), plasma and urine samples were obtained from 61 immune-mediated diseases patients treated or not with infliximab in combination with steroid and other immunomodulators and from 20 healthy donors. JCV DNA was transiently detected in 12 PBMC of 40 patients at different doses of infliximab with a higher prevalence than that of the 21 patients untreated. Conversely, a stable JCV positivity in urine of treated and untreated patients was detected. Sequencing the noncoding control region (NCCR), all samples exhibited the archetype structure with few mutations in transcriptional factor binding regions. The consequence of anti-TNF-α treatment on viral persistence was examined monitoring Torquetenovirus viremia and investigating the TNF-α-induced microRNA regulators of transcriptional factors, with a binding site on NCCR. Although infliximab treatment in this study did not affect directly JCV reactivation, further investigation on host factor(s) regulated by it will be of warranty in the understanding the mechanism(s) that may affect viral persistence. © 2012 Journal of NeuroVirology, Inc
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
Epidemiologia del virus West Nile in Italia
No full textNegli ultimi 10 anni le malattie emergenti o riemergenti hanno destato l’attenzione della comunità internazionale. Il virus West Nile, che si supponeva limitato a determinate aree dell’Africa, si è diffuso in Europa e negli Stati Uniti in seguito a fenomeni come il cambiamento climatico, che ha influito anche sulle rotte degli uccelli migratori, o il fenomeno della globalizzazione, che di fatto ha causato l’abbattimento delle barriere naturali. Il virus West Nile è stato isolato per la prima volta nel 1937 in Uganda nel distretto del Nilo occidentale. Dopo il primo isolamento, sporadiche epidemie sono state registrate in Africa, Medio oriente ed in alcune zone dell’Asia. La diffusione del virus nell’emisfero occidentale è iniziata nel 1999 a New York, probabilmente in seguito all’introduzione da parte di zanzare o uccelli infetti, propagandosi nell’arco dei successivi dieci anni in tutti gli Stati Uniti. In Italia la prima epidemia si è registrata nel 1998 in Toscana tra i cavalli di alcuni allevamenti. Dopo un silenzio di 10 anni il virus è ricomparso nelle regioni del nord-est, dove si sono registrati casi di malattie neuro-invasive sia nei cavalli che nell’uomo in Veneto ed in Emilia-Romagna. Lo scopo di questo studio era di valutare la circolazione del virus West Nile in Italia, con particolare attenzione per quelle aree attualmente non considerate endemiche per questo agente infettivo. Un altro obiettivo che questo lavoro si è posto è stato quello di valutare differenti antigeni, sia quelli descritti in letteratura, come il dominio DIII della proteina dell’envelope (E), la porzione N-terminale della proteina NS5 e la proteina PrM/M, sia nuovi antigeni come la regione corrispondente ai domini DI e DII della proteina E, allo scopo di valutarne sensibilità e specificità. A tale scopo abbiamo prodotto due proteine ricombinanti corrispondenti al dominio III (DIII), altamente antigenico, e ai domini DI e DII. Inoltre, per aumentare la capacità discriminatoria del nostro sistema, abbiamo prodotto altri due antigeni, descritti in letteratura come altamente specifici: le proteine NS5 e PrM/M. Le proteine ricombinanti sono quindi state testate in western blot con un pannello di sieri umani. I risultati mostravano come la proteina PrM/M fosse aspecifica, la proteina NS5 poco sensibile mentre l’antigene DIII mostrava una sensibilità e specificità rispettivamente dell’86% e dell’87%. I sieri umani erano testati anche con la metodica ELISA, ma i risultati con gli antigeni PrM/M e NS5 erano comparabili a quelli ottenuti in western blot mentre la sensibilità e la specificità sia per l’antigene DIII che per l’antigene DI/DII erano rispettivamente del 78,6% e del 93%. Poiché i due antigeni identificavano in modo differente i campioni positivi e negativi, si sono considerati i risultati dei due test non separatamente ma in modo complementare, ottenendo valori di sensibilità e specificità rispettivamente del 100% e dell’87%. Sulla base di questi dati le proteine PrM/M e NS5 non sono state impiegate in questo studio. Allo scopo di studiare la diffusione del WNV in Italia, abbiamo analizzato i cavalli dell’Esercito Italiano che sono dislocati su tutto il territorio nazionale. In questa prima fase del progetto abbiamo analizzato 360 sieri di cavallo raccolti nel 2009 e nel 2011 nel Lazio, nelle Marche ed in Sardegna. Allo scopo di valutare il nostro test immunoenzimatico, abbiamo eseguito il test di sieroneutralizzazione su tutti i campioni. Questo test identificava 11 campioni positivi, nove dei quali erano di soggetti vaccinati mentre due erano effettivamente positivi al virus. I campioni sono stati quindi analizzati con il test ELISA ed i risultati mostravano una maggiore sensibilità e specificità dell’antigene DIII rispetto all’antigene DI/DII. Il risultato dei due antigeni insieme confermava tutti i campioni vaccinati ed uno dei due campioni positivi, mostrando una minore sensibilità e specificità rispetto a quanto osservato con i sieri umani. In conclusione, la scelta di impiegare entrambi gli antigeni ricombinanti dell'envelope nei test sierologici per lo screening dei campioni risulta promettente. Per quanto riguarda l’indagine epidemiologica, i dati raccolti indicano l’assenza di circolazione del virus nelle aree esaminat
Respiratory viral infections in ICU patients: comparison of upper and lower respiratory samples
No full textRespiratory viruses cause many diseases, from mild to severe illnesses, and contribute significantly to morbidity and mortality worldwide. Different viruses can establish respiratory tract infections, they belong to the Orthomyxoviridae, Coronaviridae, Picornaviridae, Paramyxoviridae, Adenoviridae, Parvoviridae and in immunocompromised patients Herpesviridae families. Altogether, the etiologic diagnosis of respiratory viral infections has been underestimated so far. In patients with predisposing conditions the outcome of these infections can be more severe, sometimes requiring hospitalization, even in intensive care units (ICU), because of the development of pneumonia and acute respiratory distress syndrome (ARDS). For these patients, in particular, rapid diagnosis is essential. In addition, in ICU patients the significance of the detection of some members of Herpesviridae family, like HSV1, CMV and EBV, is controversial. The aim of this study was to clarify the prevalence of respiratory viruses and herpesviruses, and their role in ICU patients. Large part of this study was devoted to the development of diagnostic assays able to accurately characterise respiratory viruses quickly and at the lowest costs. Viral detection was performed in both upper and lower respiratory samples in order to compare the viral populations in these two compartments and, possibly, to draw informations concerning the role of the infection in severe cases.
Four duplex RT real-time PCRs, using EvaGreen fluorescent dye, were developed to identify and characterize the main respiratory RNA viruses directly from clinical samples. A duplex was performed to detect influenza A and influenza B viruses; a second duplex was performed to detect PIVs belonging to Respirovirus genera (PIV1 and PIV3) and RSV; the viruses target for the third duplex PCR were PIV type 2 and hMPV; and a fourth duplex was performed to detect CoV I and EV/RV.
The results of the duplex real-time PCRs were confirmed by sequencing positive samples and by comparison with other assays, including commercial, validated, assays, which gave similar results. A total of 156 clinical samples from upper and lower respiratory tract of 58 adult patients hospitalized in ICU were analysed. In 80% of positive adult patients influenza A viruses were detected, in 8% influenza B viruses and rhinovirus/enterovirus and in 4% metapneumoviruses. In particular in all ICU adult patients positive for influenza A or B viruses, the virus was demonstrated in both upper or lower respiratory tract samples. For an adult patient positive for RV/EV, the virus was detected in both samples; while for another only the upper respiratory tract sample was positive. Only one upper respiratory tract sample from one patient was positive for hMPV. The results obtained in this study were in agreement with other published studies that showed influenza virus as the most common virus detected in ICU patients, followed by rhinoviruses.
Furthermore, three nested PCRs were developed to detect herpesviruses (CMV, EBV and HSV1). To understand better the role of these viruses in ICU patients all herpesviruses positive clinical samples obtained by nested-PCRs were further analyzed by quantitative real-time PCRs.
Altogether, 37 of 58 (about 64%) patients were positive for one or more herpesviruses.
EBV was detected in 25 patients of 58, either as single or mixed infection; CMV and HSV1 were detected in 15 patients either as single or mixed infection. Mixed infections were not rare.
In general, for EBV viral load in TS samples was higher than in BAL samples. These results could suggest a possible viral contamination of the lower respiratory tract from mouth or throat or both. In one case EBV DNA was detected in the BAL only in two successive specimens at a low viral load (103-104). Further monitoring should be performed to better understand these data.
In this study CMV was detected as single infection only in two patients. Regarding CMV association with pneumonia, the average values of viral load reported in literature vary; however a viral load in BAL samples, between 4,6x104 and 5x105 copies number/ml, has been proposed as a threshold for the diagnosis of pneumonia. None of the patients analysed in this study had a viral load within this range only in BAL sample.
HSV1 was detected in 15 patients of 58 as single or mixed infection. In general, all patients HSV1 positive had high viral load in TS and in BAL samples (average value 106). In one patient only the detection of a high viral load in the BAL in absence of viral DNA in the TS could suggest an involvement of this virus in the lower respiratory tract disease.
The assays described could be particularly useful to screen a large number of patients for epidemiological studies and to assess the prevalence in the lower and upper respiratory tract of ICU patients with, regarding CMV, EBV and HSV1, the ultimate goal to understand the clinical significance of this phenomenon.
The possible contribute of the use of the NGS to the knowledges of the viruses involved in upper and lower respiratory tract infections was also studied preliminary in a small number of ICU patients. Nextera-XT protocol to MiSeq platform has been used
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