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Presence of Human Herpesvirus-8 variants in the oral tissues of Human Immunodeficiency Virus-infected Persons
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Molecular analysis of hepatitis B virus transmission events
Get PDFSelective percutaneous transmission by hepatitis B virus (HBV) and breakthrough perinatal HBV infection in fully immunized infants can occur. This study describes investigations into the virologic bases for these phenomena. The phenomoenon of selective percutaneous HBV transmission was discovered from the finding of transmitter/recipient HBV sequence discordance in two clusters of post-surgical HBV infection. Using limiting dilution, PCR-cloning, single-strand conformation polymorphism and nucleotide sequencing analyses, the discordance was found to be correlated with extreme viral diversity and low-level viraemia in the transmitters, and to transmission of minority variants. By contrast, in five cases where there was transmitter/recipient HBV sequence concordance, the transmitters carried relatively homogeneous HBV populations at high viraemia levels, and the most populous variant was transmitted. Fourteen fully immunized children born to HBV carrier mothers were found to have undergone breakthrough perinatal infection. In twelve infants, viral sequences were identical to those in their mothers. When these sequences were compared to 22 other mother/infant pairs in which the infants remained uninfected, a high maternal viral load (>108 genome copies/ml) and specific base changes in the HBV S gene (G365, A328, A479, C158, and C377) were found to be correlated with increased risk of infection. The two other HBV-positive infants were infected by putative vaccine-escape mutants, as there was sequence discordance between the S gene amplified from them and from their mothers. Specially developed amplification refractory mutation systems identifed the variants in these infants as having originated maternally. This study therefore shows that: (1) the degree of HBV heterogeneity in carriers can be extreme; (2) following percutaneous exposure, selective transmission is due to transmission of minor variants; (3) high maternal viraemia and specific base changes in the HBV S gene are associated with breakthough perinatal infection; and (4) vaccine- escape HBV mutants pre-exist in the mother
Multitypic hepatitis C virus infection identified by real-time nucleotide sequencing of minority genotypes
No full textThe prevalence of concurrent multitypic hepatitis C virus (HCV) infection is uncertain. A sensitive and specific approach to identifying minority HCV genotypes in blood is presented. Following serum extraction and reverse transcription PCR to amplify cDNA originating from the viral 5′ noncoding region, the amplified product mixture was treated with genotype-specific restriction endonuclease to digest the dominant genotype. Residual amplicons were subjected to PCR cloning and then to real-time DNA sequencing using a Pyrosequencer to identify the remaining genotypes. Dilution experiments showed that minority genotypes may be detected when they represent 1:10,000 of the total population and in serum specimens with viral loads as low as 1,000 IU/ml. Of 37 patients with bleeding disorders and 44 injecting drug users, infection by more than one HCV genotype was found in 7 (19%) and 4 (9%) patients, respectively. The low rate of detection in people at high risk of repeated HCV infection suggests that multitypic HCV carriage is uncommon
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
Emerg Infect Dis
No full textIn 2005, 329 cases of hepatitis E virus infection were confirmed in England and Wales; 33 were confirmed indigenous infections, and a further 67 were estimated to be indigenous infections. Hepatitis E should be considered in the investigation of patients with hepatitis even if they have no history of travel
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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