1,720,998 research outputs found
Nanofarmacologia
No full textScopo di questo capitolo è introdurre il lettore a un ambito della farmacologia di recente sviluppo, la “nanofarmacologia”
Human plasma retinol-binding protein (RBP4) is also a fatty acid-binding protein
Full text linkRBP4 (plasma retinol-binding protein) is the 21 kDa transporter of all-trans retinol that circulates in plasma as a moderately tight 1:1 molar complex of the vitamin with the protein. RBP4 is primarily synthesised in the liver but is also produced by adipose tissue and circulates bound to a larger protein, transthyretin, TTR, that serves to increase its molecular mass and thus avoid its elimination by glomerular filtration. This paper reports the high resolution three-dimensional structures of human RBP4 naturally lacking bound retinol purified from plasma, urine and amniotic fluid. In all these crystals we found a fatty acid molecule bound in the hydrophobic ligand-binding site, a result confirmed by mass spectrometry measurements. In addition we also report the 1.5 Å resolution structures of human holo-RBP4 and of the protein saturated with palmitic and lauric acid and discuss the interaction of the fatty acids and retinol with the protein
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
Can we obtain new information from old protein crystals? The plasma retinol-binding protein case.
Full text linkRBP4 (plasma retinol-binding protein) is the 21 kDa transporter of all-trans retinol that circulates in plasma as a moderately tight 1:1 molar complex of the vitamin with the protein. RBP4 is primarily synthesised in the liver but is also produced by adipose tissue and circulates bound to a larger protein, transthyretin, TTR, that serves to increase its molecular mass and thus avoid its elimination by glomerular filtration [1]. Many years ago we published the structure of RBP4 holo and believed to be apo at 2.5 Å resolution [2] and wrote at the end of the abstract “In the case of the unliganded form, the central cavity that is occupied by the vitamin in the two human crystalline holo RBPs, is filled by electron density that, at the present resolution we interpret as solvent.” The crystals used for that study had been prepared by microdialysis using protein purified from human plasma and, since they were still kept in our laboratory, we decided to test them at the ESRF a couple of years ago. We collected a full data set of both the liganded and unliganded crystals at a resolution of 1.5 Å and 2.0 Å respectively and were able to refine the unliganded form using about 20,000 reflections instead of the 10,000 that we had used in the original paper. The result was that we identified a fatty acid in the ligand-binding site of the protein believed to be apo. It is remarkable that the data for the holo and “apo” protein purified from plasma could be collected using crystals from the same batch as those of the structures published more than 20 years ago. The significantly increased resolution can be attributed to the amazing developments in the X-ray data collection methods that occurred during the intervening years and was only possible thanks to the stability of protein crystals prepared by equilibrium dialysis. We also prepared crystals of RBP4 purified from human urine and amniotic fluid, two sources of protein that contain non fluorescent RBP4, i.e. not bound to retinol, and for that reason believed to be the apo form of the protein. In every case we found a fatty acid in the central cavity of the RBP4 molecule, a result that we confirmed by GC-MS analysis of the samples used in the crystallization experiments. This result changes substantially our perception of this protein that has so far been considered to be specific for retinol and is a good example of how simply increasing the quality of the diffraction data can change the perception of the function of a protein [3
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
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