1,721,002 research outputs found
Structural insights into the enzyme specificity of a novel omega-transaminase from the thermophilic bacterium Sphaerobacter thermophilus
No full textTransaminases are pyridoxal 5'-phosphate-dependent enzymes that reversibly catalyze transamination reactions from an amino group donor substrate to an amino group acceptor substrate. omega-Transaminases (omega TAs) utilize compounds with an amino group not at alpha-carbon position as their amino group donor substrates. Recently, a novel omega TA with broad substrate specificity and high thermostability from the thermophilic bacterium Sphaerobacter thermophilus (St-omega TA) has been reported. Although St-omega TA has been biochemically characterized, little is known about its determinants of substrate specificity. In the present study, we determined the crystal structure of St-omega TA at 1.9 angstrom resolution to clarify in detail its mechanism of substrate recognition. The structure of St-omega TA revealed that it has a voluminous active site resulting from the unique spatial arrangement of residues comprising its active site. In addition, our molecular docking simulation results suggest that substrate compounds may bind to active site residues via electrostatic interactions or hydrophobic interactions that can be induced by subtle rearrangements of active site residues. On the basis of these structural analyses, we propose a plausible working model of the enzymatic mechanism of St-omega TA. Our results provide profound structural insights into the substrate specificity of St-omega TA and extend the boundaries of knowledge of TAs.N
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
Altered expression of fucosylation pathway genes is associated with poor prognosis and tumor metastasis in non-small cell lung cancer
No full textFucosylation is a post-translational modification that attaches fucose residues to protein- or lipid-bound oligosaccharides. Certain fucosylation pathway genes are aberrantly expressed in several types of cancer, including non-small cell lung cancer (NSCLC), and this aberrant expression is associated with poor prognosis in patients with cancer. However, the molecular mechanism by which these fucosylation pathway genes promote tumor progression has not been well-characterized. The present study analyzed public microarray data obtained from NSCLC samples. Multivariate analysis revealed that altered expression of fucosylation pathway genes, including fucosyltransferase 1 (FUT1), FUT2, FUT3, FUT6, FUT8 and GDP-L-fucose synthase (TSTA3), correlated with poor survival in patients with NSCLC. Inhibition of FUTs by 2F-peracetyl-fucose (2F-PAF) suppressed transforming growth factor beta (TGF beta)-mediated Smad3 phosphorylation and nuclear translocation in NSCLC cells. In addition, wound-healing and Transwell migration assays demonstrated that 2F-PAF inhibited TGF beta-induced NSCLC cell migration and invasion. Furthermore, in vivo bioluminescence imaging analysis revealed that 2F-PAF attenuated the metastatic capacity of NSCLC cells. These results may help characterize the oncogenic role of fucosylation in NSCLC biology and highlight its potential for developing cancer therapeutics.Y
Icilin induces G1 arrest through activating JNK and p38 kinase in a TRPM8-independent manner
No full textAberrant regulation of cell cycle confers a limitless replicative potential, which is a hallmark of cancer. Currently, the compounds targeting the cell cycle are undergoing cancer clinical trials. In this study, we demonstrated that icilin, a cooling compound, induces Cl arrest in PC-3 prostate cancer cells without cell death. Icilin modulated the expression level of various cell cycle regulators at transcription or post-translational levels. In addition, icilin activated JNK and p38 kinase pathways, but not ERK. Both JNK and p38 kinases cooperatively mediated icilin-induced Cl arrest, which was rescued by pharmacologic inhibition of these kinases. The action of icilin on Cl arrest was unrelated to the activation of TRPM8 calcium channel. Our findings suggest that icilin is a valuable chemical probe for future investigation aiming at delineating the molecular mechanisms of cell cycle regulation in prostate cancer. (C) 2011 Elsevier Inc. All rights reserved
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
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