1,720,961 research outputs found
Tat-mediated delivery of human alanine:glyoxylate aminotransferase in a cellular model of Primary Hyperoxaluria Type I
No full textDefects in liver peroxisomal alanine:glyoxylate aminotransferase (AGT), as a consequence of inherited mutations on the AGXT gene, lead to primary hyperoxaluria type I (PH1), a rare metabolic disorder characterized by the formation of calcium oxalate stones at first in the urinary tract and then in the whole body. The curative treatments currently available for PH1 are pyridoxine therapy, effective in only 10–30 % of the patients, and liver transplantation, an invasive procedure with potentially serious complications. A valid therapeutic option for PH1 patients would be the development of an enzyme administration therapy. However, the exogenous administration of the missing AGT would require the crossing of the plasma membrane to deliver the protein to liver peroxisomes. In this study, we constructed, purified and characterized the fusion protein of AGT with the membrane-penetrating Tat peptide (Tat-AGT). Although Tat-AGT shows subtle active site conformational changes as compared with untagged AGT, it retains a significant transaminase activity. Western-blot analyses, enzymatic assays and immunofluorescence studies show that active Tat-AGT can be successfully delivered to a mammalian cellular model of PH1 consisting of chinese hamster ovary cells expressing glycolate oxidase (CHO-GO), whereas untagged AGT cannot. Moreover, the intracellular transduced Tat-AGT makes CHO-GO cells able to detoxify endogenously produced glyoxylate to an extent similar to that of CHO-GO cells stably expressing AGT. Altogether, these results show that the Tat peptide is capable of delivering a functional AGT to mammalian cells, thus paving the way for the possibility to use Tat-AGT as an enzyme replacement therapy to counteract PH1
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
Conformational and Biochemical Characterization of a Biologically Active Rat Recombinant Protease Nexin-1 Expressed in E. coli
No full textProtease Nexin-1, a 43-kDa glycoprotein, is a major physiological thrombin inhibitor involved in the modulation of
nerve cell plasticity. Recombinant rat Protease Nexin-1 (rPN-1) was efficiently produced in Escherichia coli using a
T7RNA polymerase based expression system and purified by heparin-sepharose affinity chromatography yielding
3 mg of protein per liter of cell culture. The purity and chemical identity of rPN-1 were assessed by SDS-PAGE,
Reverse Phase- High Performance Liquid Chromatography, mass spectrometry and two-dimensional-gel
electrophoresis. Conformational analysis by circular dichroism and fluorescence spectroscopy revealed the
presence of mixed α/β secondary structure and the prevailing localization of Trp-residues in rather polar
environments. Fluorescence titration of rPN-1 with heparin indicated that rPN-1 binds heparinwith high affinity.
Furthermore, the formation of a SDS-stable 1:1 thrombin–rPN-1 complex, monitored by SDS-PAGE, confirmed the
native-like structure of rPN-1. Finally, the cellular effects of rPN-1, such as its ability to promote neurite outgrowth
in neuroblastoma cells, were found to be very similar to those elicited by natural PN-1. Altogether, our results
demonstrate that glycosylation does not alter neither structure nor function of PN-1 and that E. coli is a suitable
expression system for obtaining milligram quantities of pure and fully active rPN-1 for structural and functional studies
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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