1,721,010 research outputs found
Role of antiviral treatment for HCC prevention
No full textChemoprevention of hepatocellular carcinoma (HCC) is listed as a yet highly debated long-term benefit of a successful treatment of patients with chronic viral hepatitis. In the hepatitis B virus (HBV) arena, the retrospective scrutiny of both interferon and nucleos(t) ide analogues (NUC) studies failed to provide robust evidence for HCC chemoprevention, due to a number of confoundings in the studies that were originally designed to assess the antiviral activity of interferon therapy. However, the reanalysis of outcomes following patients stratification for risk factors of HCC, provided a clue to find an association between NUC therapy and a reduced risk of liver cancer in non cirrhotic patients, only. In the hepatitis C scenario, a meta analysis of 30 observational studies of patients treated with interferon demonstrated a more than 70% reduction of HCC risk occurring independently of severity of underlying liver fibrosis which was less pronounced in aged patients and those with more advanced liver fibrosis. While the reasons for the residual risk of HCC in virological responders remain largely unexplained, international societies recommend surveillance for HCC of both HBV and HCV responders to antiviral therapy
Prevention of hepatocellular carcinoma
No full textPrevention is the only realistic approach for reducing mortality rates associated with hepatocellular carcinoma (HCC) worldwide. Vaccination against hepatitis B and screening of blood donations are effective measures of primary prevention. Screening of blood donations has led to a substantial reduction in viral hepatitis transmission among the general population, and in Taiwan vaccination against hepatitis B caused a significant reduction in HCC incidence among infants. Primary prevention also includes approaches that alter epigenetic and genetic changes in hepatocytes, known to increase susceptibility to HCC, as well as treatments slowing progression to cirrhosis. The only evidence that chemoprevention reduces HCC risk is a multicenter randomized prospective study, in Asian patients with advanced hepatitis B who received the oral nucleoside analogue lamivudine. Circumstantial evidence suggests that HCC risk is also reduced in patients with chronic hepatitis C who have had a sustained virological response to interferon therapy. HCC is not substantially reduced in patients with hepatitis B treated with interferon and patients with hepatitis C who did not respond to interferon. Secondary prevention, that is, prevention of tumor recurrence after hepatic resection or local ablative therapies, has been pursued with different approaches. Retinoids, hepatic embolization with 1311 lipiodol, and adoptive adjuvant immunotherapy have yielded encouraging results. Other approaches, including those based on interferon alfa or P, provided inconclusive evidence for secondary prophylaxis of HCC, mainly because of the poor methodologies and scientific background of the studies. Dietary interventions and antiaflatoxin agents might help to prevent HCC in susceptible individuals, but the real efficacy of these approaches is far from being demonstrated
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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