1,720,975 research outputs found
Expression of a human polyomavirus oncoprotein tumour suppressor proteins in medulloblastomas
No full textAims - Although the aetiology of medulloblastoma remains elusive several lines of evidence suggest an association with the human neurotropic polyomavirus JC its oncoprotein T antigen. The tumour forming properties of JC virus T antigen are the result at least in part of its ability to bind inactivate tumour suppressor/ cell cycle regulatory proteins such as p53 the retinoblastoma family of proteins. Methods - To examine potential relations between these factors immunohisto-chemistry was used to determine associations between the T antigen the expression of p53 the retinoblastoma proteins pRb p107 Rb2/p130 in eight medulloblastomas. Results - Only the three medulloblastomas with T antigen expression also showed nuclear positivity with antibodies to p53. Although immunohistochemistry detected nuclear labelling for pRb in five of the cases, the three that were positive for T antigen showed the highest pRb labelling. The retinoblastoma related proteins p107 and Rb2/p130 were also immunopositive in most T antigen positive medulloblastomas. Double label immunohistochemistry also demonstrated p53 and pRb positivity in the same cells that were T antigen positive. Conclusions - These correlations suggest that associations between T antigen and p53 and/or T antigen and pRb occur in some of these tumours. These data provide indirect evidence that JC virus, acting through T antigen, might be involved in the formation and progression of medulloblastoma
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
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
The cellular response of JC Virus T-Antigen induced brain tumor implants to a murine intra-ocular model
No full textIn order to define the immunologic response to central nervous system tumors in a controlled fashion, we compared xenogeneic, allogeneic and syngeneic transplants of JC virus-induced neural tumor cell aggregates implanted into anterior ocular chambers of mice. Semiquantitative assessment of the level of leukocyte common antigen (CD45) of the transplants by immunohistochemistry was used to gauge rejection. Reticulin staining was used to monitor vascularization. Immunoreactivity to the viral oncoprotein, T- antigen, was confirmed by immunohistochemistry and immunoprecipitation/Western blot analysis. The results demonstrated that transplants were viable at all time-points and developed vascularization as early as three days after transplantation. Xenotransplants, 13-days post- transplantation, and allogeneic transplants, 25 days post-transplantation were infiltrated with polymorphonuclear leukocytes. Fewer CD45 positive cells were demonstrated in syngeneic transplants. High levels of JCV T-antigen stimulated rejection in syngeneic transplants. These results establish a model for further investigation of the natural and induced immunologic response to central nervous system tumors. (C) 2000 Published by Elsevier Science B.V
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