1,721,107 research outputs found
Conversion of Enkephalin and Dermorphin into δ‐Selective Opioid Antagonists by Single‐Residue Substitution
No full textThe properties of di- and tri-peptides containing 1,2,3,6tetrahydroisoquinoline-3-carboxyliacc id
(Tic) in second position suggest that the message domain of opioid peptides can be composed of
only two residues [Temussi, P. A., Salvadori, S., Amodeo, P., Guerrini, R., Tomatis, R., Lazarus, L.
H., Picone, D. & Tancredi, T. (1994) Biochem. Biophys. Res. Commun. 198, 933-9391. As a crucial
test of the possibility that the Tyr-Tic segment be a message domain in longer peptide sequences,
we have inserted it in the sequences of two typical opioid peptides: [Leulenkephalin, a non-selective
agonist, and dermorphin, a selective p agonist. Here we report the synthesis and biological activity
of [~-Tic’]enkephalin, [~-Tic~]dermorphi[n~,- Tic’]dermorphin carboxylic acid and [~-Tic’]dermorphin:
all [L-Tic’lpeptides were converted from agonists to &selective antagonists. The NMR conformational
study in a dimethylsulfoxide/water cryoprotective mixture at low temperature shows diagnostic
side-chain-side-chain NOES in the spectra of all [~-Tic’]peptides and hints that the 90”
arrangement of the the two aromatic rings found in the cis-Tyr-L-Tic moiety, typical of N-methyl
naltrindole and other 6-selective opiate antagonists, is responsible for the antagonist activity of all
these peptides
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
Solution structure of insect CSP and OBPs by NMR
No full textInsect odorant binding proteins (OBPs) and chemosensory proteins (CSPs) are proteins deputed to the solubilization, transport and stabilization of lipophilic and odorant compounds. These proteins have a conserved fold, which undergoes massive structural rearrangements in order to accommodate medium to large-sized lipophilic ligands. Solution NMR spectroscopy, due to its intrinsically dynamic nature, is the perfect technique to extrapolate structural information and dynamic parameters and to elucidate the conformational changes that occur upon ligand binding. This chapter will describe in detail the experimental protocols for the production and purification of isotope-labeled recombinant CSPs and OBPs for NMR studies. Detailed procedures for spectra acquisition, processing and analysis will be presented, focusing on the protein CSP-sg4 from Schistocerca gregaria as a model. Finally, experiments aimed at providing information on protein flexibility and ligand binding modes will also be described
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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