1,721,047 research outputs found
Interpreting serological tests in diagnosing autoimmune liver diseases
No full textAutoimmune liver diseases (ALD) are characterized by immune-mediated injury of
bile ducts or hepatocytes, thus including cholangiopathies such as primary
biliary cirrhosis (PBC), primary sclerosing cholangitis, and autoimmune
hepatitis. Further, ALD variants manifesting with both hepatocellular and
cholangiocellular damage are becoming more common. Serum autoantibodies, together
with imaging and histology, are critical to the diagnostic process when ALD is
suspected. Because an early diagnosis can influence prognosis, the development of
sensitive and specific tests for serum autoantibodies should be a priority for
researchers to ensure a more efficient noninvasive workup. Little prognostic
value has been observed for any of the ALD serum hallmarks, and a vigorous effort
to investigate new and old markers should therefore be undertaken in longitudinal
studies as in the recent paradigm of PBC-specific antinuclear antibodies. We
review herein the numerous ALD screening tests available in routine and
specialized laboratories and comment on their significance in clinical practic
The limitations and hidden gems of the epidemiology of primary biliary cirrhosis
No full textEpidemiology is expected to provide important clues to our understanding of the enigmatic etiopathogenesis of primary biliary cirrhosis (PBC). First, a systematic review of population based studies indicated a wide range in the yearly incidence (0.33-5.8/100.000) and point prevalence (1.91-40.2/100.000) rates. Though different ethnic representations may also contribute it is likely that methodological issues, based on the retrospective survey of diagnosed cases, and time trend play a major role, also in view of the prolonged asymptomatic period of the disease. Of note, the highest prevalence rates (35-40/100.000) were found in areas characterized by high medical awareness and easier access to healthcare. Second, the search for serum AMA in unselected population sera may identify the largest possible number of patients who have or will develop the disease. Indeed, a surprisingly high AMA prevalence rate, ranging between 0.43 and 1%, appears likely in the general population despite the lack of adequate work-up in most studies. Third, the median female to male ratio for PBC is classically accepted as 9-10:1 but is significantly lower for AMA prevalence (2.5:1), death certificates for PBC (4.3:1) and liver transplantation (6:1), thus suggesting that PBC in men may be underdiagnosed in early stages or manifest a more severe progression. Lastly, studies of both PBC and serum AMA prevalence among family members and monozygotic twins strongly support the role played by genetic factors in the etiopathogenesis of the disease. In conclusion, PBC epidemiology is far from being a closed case and the numerous open issues will be solved through a collaborative effort and powerful data mining tools
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
Primary biliary cirrhosis and autoimmune cholangitis
No full textPrimary biliary cirrhosis (PBC) is a chronic cholestatic liver disease of unknown etiology characterized by hightiter serum antimitochondrial autoantibodies (AMAs) and an autoimmune-mediated destruction of the small and mediumsized intrahepatic bile ducts. From a clinical standpoint, PBC is a peculiar, yet representative, autoimmune disease (Table). It affects women more frequently than men, with a female-to-male ratio of 9 to 1, and the average age at diagnosis is within the fifth and sixth decades of life, with exceptional cases described in pediatric ages. Epidemiological data indicate a geographical pattern of PBC prevalence and incidence rates, which are higher in northern countries (England, Scandinavia, northern United States). The diagnosis of PBC is made when two of three criteria are fulfilled, i.e., presence of serum AMAs, increased enzymes indicating cholestasis (i.e., alkaline phosphatase) for longer than 6 mo, and a compatible or diagnostic liver histology. Clinical symptoms include fatigue, pruritus, and jaundice. The progression of PBC varies widely for unknown reasons, as represented by certain patients remaining asymptomatic and others reaching liver failure at young ages
Innate immunity and primary biliary cirrhosis
No full textThere has been a rapid growth in our understanding of the molecular bases of primary biliary cirrhosis (PBC). These efforts were initiated when the immunodominant mitochondrial autoantigen was cloned and sequenced. Using the recombinant cloned antigen as a tool, research has focused on the effector mechanisms of disease and the uniqueness of the primary target tissue, the intrahepatic bile ducts. Most recently, there have been experimental data suggesting that innate immunity changes may be critical to the initiation and perpetuation of the autoimmune injury, as in the case of the enhanced response of monocytes and memory B cells to infectious stimulation and environmental mimics. These observations are important as they help fill in the many gaps which remain on the most difficult subject of autoimmunity, etiology. Indeed, based on the available data, several experimental models of PBC have been developed. These models illustrate and suggest that PBC can be initiated by several mechanisms, all of which lead to loss of tolerance to the mitochondrial antigens. However, once this adaptive response develops, it appears that much of the subsequent pathology is exacerbated by innate responses. We suggest that future therapeutic efforts in PBC will depend heavily on understanding the nature of this innate immune responses and methodology to blunt their cytotoxicity
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
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