1,720,965 research outputs found
Repression of the IL-6 gene is associated with hypermethylation
No full textThe expression of the IL-6 gene is usually tightly controlled and may be induced in specific tissues after treatment with appropriate stimuli. Although much is known about the inducible expression of the IL-6 gene, the molecular mechanisms responsible for its repression in specific tissues or cell types remain poorly defined. To address this question we have studied two human breast carcinoma cell lines, MDA-MB-231, in which the IL-6 gene is expressed, and, MCF-7, in which the IL-6 message is undetectable by Northern blot assay even in the presence of inducers. The expression of the IL-6 message was estimated after treatment with 5-aza-2'deoxycytidine and the methylation state of the IL-6 gene was analyzed. We show herein that treatment of MCF-7 cells with an agent which reduces DNA methylation correlates with IL-6 gene hypomethylation and increases the level of its expression
Interleukin-6 repression is associated with a distinctive chromatin structure of the gene
No full textInterleukin 6 repression is associated with a distinctive chromatin structure of the gene.
No full text
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
Biochemical properties of the PsbS subunit of Photosystem II either purified from chloroplast or recombinant
No full textThe biochemical properties of PsbS protein, a nuclear-encoded Photosystem II subunit involved in the high energy quenching of chlorophyll fluorescence, have been studied using preparations purified from chloroplasts or obtained by overexpression in bacteria. Despite the homology with chlorophyll a/b/xanthophyll-binding proteins of the Lhc family, native PsbS protein does not show any detectable ability to bind chlorophylls or carotenoids in conditions in which Lhc proteins maintain full pigment binding. The recombinant protein, when refolded in vitro in the presence of purified pigments, neither binds chlorophylls nor xanthophylls, differently from the homologous proteins LHCII, CP26, and CP29 that refold into stable pigment-binding complexes. Thus, it is concluded that if PsbS is a pigment-binding protein in vivo, the binding mechanism must be different from that present in other Lhc proteins. Primary sequence analysis provides evidence for homology of PsbS helices I and III with the central 2-fold symmetric core of chlorophyll a/b-binding proteins. Moreover, a structural homology owed to the presence of acidic residues in each of the two lumen-exposed loops is found with the dicyclohexylcarbodiimide/Ca2+-binding domain of CP29. Consistently, both native and recombinant PsbS proteins showed [14C]dicyclohexylcarbodiimide binding, thus supporting a functional basis for its homology with CP29 on the lumen-exposed loops. This domain is suggested to be involved in sensing low luminal pH
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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