1,720,970 research outputs found
Cyclic Analogs of Wasp Kinins From Vespa-analis and Vespa-tropica
No full textSyntheses are described of two bradykinin-like kinins isolated from Vespa analis (G-R-P-P-G-F-S-P-F-R-V-I, VSK-A) and Vespa tropica (G-R-P-Hyp-G-F-S-P-F-R-V-V, VSK-T) and of their cyclic analogues. Linear dodecapeptides were prepared by the solid-phase procedure based on Fmoc-chemistry, and cyclization was carried out by the diphenyl-phosphorazide method. Peptides were characterized by amino acid analysis, optical rotation, analytical HPLC and FAB-MS, The conformational features of the cyclic and linear kinins were determined by circular dichroism measurements in water, 95% trifluoroethanol and 8 M guanidinium chloride. Consistent with previous findings, preliminary pharmacological experiments on smooth muscle preparations showed that cyclic wasp kinins were 50-100 times less potent than their linear analogues. Moreover, cyclo-VSK-A and cyclo-VSK-T behave like kininase inhibitors by preventing the degradation of straight kinins. (C) Munksgaard 1995
Cyclic Analogs of Thr(6)-bradykinin, N-epsilon-Lys-bradykinin and Endo-Lys(8a)-vespulakinin-1
No full textSyntheses are described of the endo-Lys(8a)-vespulakinin 1 and of cyclo-Thr(6)- and cyclo-N-epsilon-Lys-bradykinin. The linear peptides covering the entire sequences of endo-Lys(8a)-VSK-1 and Thr(6)-BK, and the decapeptide containing all residues constituting Lys-BK, with a Arg-Lys peptide bond involving the epsilon-amino function of lysine, were prepared by the solid-phase procedure based on Fmoc chemistry. Cyclization was carried out by the diphenylphosphorazide method. The amino-terminal octapeptide sequence of vespulakinin 1, Fmoc-Thr(tBu)-Ala-Thr(tBu)-Thr(tBu)-Arg(Pmc)-Arg(Pmc)-Arg(Pmc)-Gly-OH, and its N-alpha-Boc-[(Gal beta)Thr(3), (Gal beta)Thr(4)]-analogue, were used to prepare N-alpha-(1-8 VSK 1)-cyclo-N-epsilon-kallidin and N-alpha-[(Gal beta)Thr(3), (Gal beta)Thr(4), 1-8 VSK 1]-cyclo-N-epsilon-kallidin. Peptides and glycopeptides were characterized by amino-acid analysis, optical rotation, analytical HPLC and FAB-MS. Consistent with previous findings, preliminary pharmacological experiments on smooth muscle preparations showed that the cyclic, or partially cyclic, analogues were significatively less potent than the linear ones. (C) Munksgaard 1995
Synthesis and Biological-activity of Some Linear and Cyclic Kinin Analogs
No full textSyntheses are described of some linear and cyclic kinin analogues. Cyclization, by the diphenyl-phosphorazide method, of linear peptides prepared by the solid-phase procedure based on Fmoc chemistry, was used for preparing cyclo-bradykinin and cyclo-kallidin (cyclo-Lys-bradykinin). Removal of the protecting group from the lysine side chain of cyclo-kallidin followed by acylation with the N-terminal sequence of vespulakinin 1 (VSK 1), Fmoc-Thr(tBu)-Ala-Thr(tBu)-Thr(tBu)-Arg(Pmc)-Arg(Pmc)-Arg(Pmc)-Gly-OH, by the Bop-HOBt procedure, yielded the protected N-epsilon-(1-8 VSK 1)-cyclo-N-alpha-kallidin, which was deblocked by acid treatment and purified by semi-preparative HPLC. The diglycosylated 1-8 VSK 1 sequence Boc-Thr(tBu)-Ala-(Gal beta)Thr-(Gal beta)Thr-Arg(Pmc)-Arg(Pmc)-Agr(Pmc)-Gly-OH was also synthesized by the solid-phase procedure and used to prepare the N-epsilon-[(Gal beta)Thr(3), (Gal beta)Thr(4), 1-8 VSK 1]-cyclo-N-alpha-kallidin. Peptides and glycopeptides were characterized by amino acid analysis, optical rotation, analytical HPLC and FAB-MS. Preliminary pharmacological experiments showed that the cyclic kinin analogues are much less potent than bradykinin but still show specific bradykinin-like actions that support the hypothesis of the presence of a pharmacophore in the centre of the (brady)kinin molecule. (C) Munksgaard 1994
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
Synthesis and Biological-activity of the Mono-galactosyl-vespulakinin-1 and Di-galactosyl-vespulakinin-1 Analogs
No full textSyntheses are described of some mono- and di-glycosylated analogues of vespulakinin 1. The solid phase procedure, based on the Fmoc chemistry, was used to prepare (Gal-alpha)Thr3-vespulakinin 1, (Gal-beta)Thr3-vespulakinin 1 and the di-glycosylated analogue ((Gal-alpha)Thr3, (Gal-alpha)Thr4-vespulakinin 1. The beta-glycosylated derivative was also prepared by the continuous flow variant of the Fmoc polyamide method. The synthesized glycopeptides were purified and characterized by amino acid analysis, optical rotation, analytical HPLC, H-1- and C-13-NMR and FAB-MS. Preliminary pharmacological experiments showed that the carbohydrate-free vespulakinin 1 is less active than bradykinin (about 0.3 times on a molar basis) when tested by guinea pig rectum contraction, and the two monoglycosylated analogues are equiactive (about 0.9 times the bradykinin activity). The most active derivative, the (Gal-alpha)Thr3, (Gal-alpha)Thr4-vespulakinin 1 analogue, was about 2.5 times as active as bradykinin
Linear and cyclic Tyr(6)- and Trp(6)-kallidin (Lys-bradykinin) analogues
No full textSyntheses are described of two kallidin (Lys-bradykinin) analogues in which the phenylalanine residue in position 6 is replaced by either tyrosine or tryptophan. The linear kinins and the two decapeptides containing all residues constituting the Tyr(6)- and the Trp(6)-kallidin were prepared by the solid-phase procedure based on Fmoc chemistry. Cyclization was carried out by both the diphenylphosphorazide and the TBTU-HOBt procedure. Peptides were characterized by amino acid analysis, optical rotation, analytical HPLC and mass spectrometry. Consistently with previous findings, preliminary pharmacological experiments on rat duodenum preparations showed that cyclic analogues were significantly less potent than the linear ones
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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