1,720,971 research outputs found
A polypyrimidine/polyourine tract within the Hmga2 minimal promoter: a common feature of many growth-related genes
No full textHMGA2 is an architectural nuclear factor which plays an important role in development and tumorigenesis, but mechanisms regulating its expression are largely unknown. The proximal promoters of the mouse and human genes coding for HMGA2 contain a conserved polypyrimidine/polypurine (ppyr/ppur) element which constitutes a multiple binding site for Sp1 and Sp3 transcription factors. In the present study we report that this region can adopt a single-stranded DNA conformation, as demonstrated in vitro by S1 nuclease sensitivity on supercoiled plasmids, indicative of an intramolecular triple-helical H-DNA structure. Moreover, we find that PTB (polypyrimidine tract binding protein), a member of the hnRNP family, binds the pyrimidine strand of Hmga2 as well as similar ppyr/ppur elements of the c-Ki-ras (R.Y) and c-myc P1 promoters. Transfection experiments indicate that non-B-DNA conformers of the ppyr/ppur tract of the Hmga2 promoter contribute to positive transcriptional activity. We propose a transcriptional mechanism, acting on the Hmga2 non-B-DNA structure and functioning through interconversion between double-stranded and single-stranded DNA, that seems to be adopted by an increasing number of genes, mainly growth-related
Design and selection of an intrabody library produced de-novo for the non-structural protein NSP5 of rotavirus.
No full textIntracellular antibodies or intrabodies have great potential in protein knockout strategies for intracellular antigens. We applied the Intracellular Antibody Capture Technology for the direct selection in yeast of a mouse scFv library (V(L)-V(H) format) constructed from animals immunised with recombinant non-structural protein NSP5 of Rotavirus. We selected five different intracellular antibodies (ICAbs), which specifically recognize Delta2, an NSP5 deletion mutant used as bait. The anti-NSP5 ICAbs were well expressed both in yeast and mammalian cells as cytoplasmic or nuclear-tagged forms. By immunofluorescence and co-immunoprecipitation assays we characterised the intracellular interaction of the five anti-NSP5 ICAbs with the co-expressed antigens
Effects of intrabodies specific for rotavirus NSP5 during the virus replicative cycle
No full textIntracellular antibodies or intrabodies (ICAbs) have great potential in protein knockout strategies for intracellular antigens. In this study, they have been used to investigate the role of the rotavirus non-structural protein NSP5 in the virus replication cycle. Intracellular antibody-capture technology was used to select single-chain Fv format (scFv) ICAbs against an NSP5 mutant. Five different specific ICAbs were selected and expressed in MA104 cells, in the scFv format, as cytoplasmic- and nuclear-tagged forms. By confocal microscopy, it was found that three of these ICAbs recognized the full-length wild-type NSP5 specifically, forming antigen-specific aggresomes in the cytoplasm of cotransfected cells. Expression of the ICAbs in rotavirus-infected cells largely reduced the assembly of viroplasms and cellular cytopathic effect. Replication of dsRNA was partially inhibited, despite there being no reduction in virus titre. These results demonstrate for the first time a key role for NSP5 during the virus replicative cycle
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
No evidence of Polyomavirus and EBV infections in Italian patients with mixed cryoglobulinemia infected chronically with HCV
No full textMixed cryoglobulinemia is a lymphoproliferative disorder associated with hepatitis C virus (HCV). In patients chronically affected by HCV the prevalence of mixed cryoglobulinemia is variable ranging from 0% to 56%. To verify whether polyomaviruses (PyV) play a role in this disorder a total of 222 blood samples from 63 HCV chronic patients, 43 with mixed cryoglobulinemia, 59 chronic lymphocytic leukemia, 50 polytransfused patients, and 50 blood donors were evaluated for Merkel (MCPyV), BKV, JCV, and SV40. EBV was additionally included in the analysis since association with this disorder has been reported. Mixed cryoglobulinemia patients infected chronically with HCV resulted negative for both PyV and EBV. MCPyV was found in 1 subject with Merkel Cell Carcinoma, in 10% of polytransfused and in 10% of blood donors while EBV was detected in 22% of polytransfused, 10% of B-cell lymphatic leukemia patients and 4% of blood donors (P < 0.01). Taken together, the absence of PyV and EBV in HCV-mixed cryoglobulinemia patients seems to exclude a direct involvement of these viruses in the pathogenesis of this disease while the presence of MCPyV in healthy individuals, at the same rate as in polytransfused patients, may reinforce data on a minimal role of this virus in other human pathologie
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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