1,721,052 research outputs found
Effects of nociceptin and analogues of nociceptin upon spontaneous dorsal root activity recorded from an in vitro preparation of rat spinal cord
No full textThe 17 amino acid peptide nociceptin has been implicated in pain modulation in the central nervous system. The effects of bath applied
nociceptin, and some analogues of nociceptin, upon spontaneous lumbar dorsal root activity have been investigated in an isolated preparation
of rat spinal cord. Nociceptin was found to reversibly depress spontaneous dorsal root activity at concentrations of 1.0 mMand 10.0 mM(IC50
2.0 mM), whereas acetyl-nociceptin at concentrations up to 10 mMhad no detectable effect. Omission of the last four amino acids (nociceptin
1–13), increased the potency of the effect upon dorsal root activity by approximately 100-fold (IC50 30 nM), but activity was lost when only
the first seven amino acids of the nociceptin molecule (nociceptin 1–7) were tested
Self-association of model transmembrane alpha-helices is modulated by lipid structure
No full textWe have developed a fluorescence quenching method using peptides containing 3,5-dibromotryrosine to measure oligomerization of model transmembrane a-helices in lipid bilayers. Peptides of the type Ac-LysLysGlyLeu(m)XLeu(n)LysLysAla-amide where X is tryptophan or 3,5-dibromotyrosine were found to form heterodimers in bilayers of phosphatidylcholine in the liquid-crystalline phase. The free energy of dimer formation changed little with increasing number of Leu residues from 16 to 22 but increased with increasing phospholipid fatty acyl chain length, with a slope of about 0.5 kJ mol(-1) per fatty acyl chain carbon. Peptides were excluded from lipid in the gel phase, resulting in increased levels of oligomerization. Addition of cholesterol to form the liquid-ordered state led to increased dimerization but without phase separation. The presence of phosphatidylethanolamine had little effect on dimerization
Effects of aromatic residues at the ends of transmembrane alpha-helices on helix interactions with lipid bilayers
No full textWe have studied the effects of aromatic residues at the ends of peptides of the type Ac-KKGLnWLmKKA-amide on their interactions with lipid bilayers as a function of lipid fatty acyl chain length, physical phase, and charge. Peptide Ac-KKGFL6WL8FKKA-amide (F2L14) incorporated into bilayers of phosphatidylcholines containing monounsaturated fatty acyl chains of lengths C14-C24 at a peptide:lipid molar ratio of 1:100 in contrast to Ac-KKGL7WL9KKA-amide (L16) which did not incorporate at all into dierucoylphosphatidylcholine [di(C24:1)PC]; Ac-KKGYL6WL8YKKA-amide (Y2L14) incorporated partly into di(C24:1)PC. Lipid-binding constants relative to that for dioleoylphosphatidylcholine (C18:1)PC were obtained using a fluorescence quenching method. For Y2L14 and F2L14, relative lipid-binding constants increased with increasing fatty acyl chain length from C14 to C24; strongest binding did not occur at the point where the hydrophobic length of the peptide equalled the hydrophobic thickness of the bilayer. For Ac-KKGYL9WL11YKKA-amide (Y2L20), increasing chain length from C18 to C24 had little effect on relative binding constants. Anionic phospholipids bound more strongly than zwitterionic phospholipids to Y2L14 and Y2L20 but effects of charge were relatively small. In two phase (gel and liquid crystalline) mixtures, all the peptides partitioned more strongly into liquid crystalline than gel phase; effects were independent of the structure of the peptide or of the lipid (dipalmitoylphosphatidylcholine or bovine brain sphingomyelin). Addition of cholesterol had little effect on incorporation of the peptides into lipid bilayers. It is concluded that the presence of aromatic residues at the ends of transmembrane -helices effectively buffers them against changes in bilayer thickness caused either by an increase in the chain length of the phospholipid or by the presence of cholesterol
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
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
- …
