1,720,956 research outputs found
Synthesis and Anti-HIV-1 activity of novel new MKC-442 analogues containing alkenyl chains or reactive functionalities in the 6-benzyl group
No full textIn an effort to obtain more insight into the anti-HIV efficacy of MKC-442 analogues (1-(alkoxymethyl)-6-benzyluracils), a new series of compounds was synthesized and evaluated for inhibition of HIV-1 replication. The modifications include a reactive center such as an aldehyde or an epoxide substituted at the benzyl group. It was believed that such reactive groups could improve the activity against HIV for the Y181C mutant by forming a covalent bond to the mercapto group in cysteine in the hydrophobic pocket. Unfortunately, only moderate activities were found in cell-based assays for such compounds against wild-type HIV and no activity against the Y181C mutant. However, higher activities were found for a corresponding oxime and the precursor molecules with butenyl and allyloxy substituents in the benzyl group. A few amino-DABO and S-DABO analogues were also synthesized, but they were found inactive against HIV
Synthesis and anti-HIV-l activity of 1,3-phenylene bis-uracil analogues of MKC-442
No full textReaction of 1,3-phenylenediacetonitrile with the zinc organometallic reagent of ethyl 2-bromobutyrate afforded the 1,3-phenylene-bis(acetoacetate) 2 which was used as the starting material for the synthesis of 1,3-phenylene-bis[6-(2-thiouracil)] 4. Desulphurization of 4 gave the corresponding bis-uracil 6, which after silylation was N-1 alkylated with bis(allyoxy)methane using TMS-triflate as the catalyst or with chloromethyl ethyl ether to give the MKC-442 analogues 7 and 9. The amino-DABO and S-DABO derivatives 11, 12a,b and 14 were also synthesized. The anti-HIV-1 activity test showed that when MKCM42 analogues were constructed with 1,3-phenylene in all cases they were detrimental to have activity against HIV-1
Synthesis and anti-HIV-1 activity of new MKC-442 analogues with an alkynyl-substituted 6-benzyl group
No full textSynthesis and antiviral activities are reported of a series of 6-(3-alkynyl benzyl)-substituted analogues of MKC-442 (6-benzyl-1-(ethoxymethyl)-5-isopropyluracil), a highly potent agent against HIV. The 3-alkynyl group is assumed to give a better stacking of the substituted benzyl group to reverse transcriptase (RT) and this was believed to improve antiviral activity against HIV-1. The bromo derivatives, 5-alkyl-6-(3-bromo-benzyl)-1-ethoxymethyl derivatives 7a, b and 5-alkyl-6-(3-bromobenzyl)-1-allyloxymethyl derivatives 9a, b, showed activity against HIV on the same level as their corresponding analogues 10a-d with a 3-trimethylsilylalkynylbenzyl substituent and their desilylated analogues 11a-d. However, they all showed activity against HIV-1 wild type in the range of more than 10fold lower than the one of MKC-442. Moderate activity against Y181C and Y181C + K103N mutated strains was also observed and, in some cases, they were marginally better than those found for MKC-442. A few amino-DABO and S-DABO analogues were also synthesized but they were found to be inactive against HIV
Novel Synthesis and Anti-HIV-1 Activity of 2-Arylthio-6-benzyl-2,3-dihydro-1H-pyrimidin-4-ones (Aryl S-DABOs)
No full textThe synthesis and the anti-HIV-1 activity of a series of 2-arylthio-6-benzyl-2,3-dihydro-1H-pyrimidin-4-ones (aryl S-DABOs) are reported. These compounds were synthesized via a coupling reaction of the corresponding 6-benzyl-2-thiouracils with aryl iodides in the presence of neocuproine hydrate, copper(I) iodide, and sodium tert-butoxide. Target compounds showed moderate activity against HIV-1
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
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