1,720,966 research outputs found
Interaction between double helix DNA fragments and the new antitumor agent sabarubicin, Men10755
No full textAmongthe disaccharide derivatives of the antitumor anthracycline doxorubicin, sabarubicin (Men10755) is
more active and less cytotoxic than doxorubicin. It showed a strong in vivo antitumor activity in all preclinical
models examined, in conjunction with a better tolerability, and is now in phase II clinical trials.
The interaction of sabarubicin andMen10749(a similar disaccharidewith a different configuration at C-40 of
the proximal sugar) with the hexanucleotides d(CGTACG)2 and d(CGATCG)2 was studied by a combined use
of 2D-1Hand 31PNMRtechniques. Both 1Hand 31P chemical shifts of imino protons and phosphates allowed
to established the intercalation sites between the CG base pairs, as it occurs for other anthracyclines of the
series. The dissociation rate constants (koff) of the slow step of the intercalation process were measured for
Men10755 and Men10749, by NMR NOE-exchange experiments. The increase of koff , with respect of doxorubicin,
showed that the intercalation process is significantly faster for both drugs, leading to an average residence
time for sabarubicin into d(CGTACG)2 sixfold shorter than for doxorubicin. This could give account of
both higher cytoplasmic/nuclear ratio and lower cellular uptake of sabarubicin in comparison with doxorubicin
and accordingly of the lower cytotoxicity of these disaccharide analogues.
A relevant number of NOE interactions allowed the structure of the complexes in solution to be derived
through restrained MD calculations. NMR-DOSY experiments were performed with several drug/oligonucleotide
mixtures in order to determine the structure and the dimension of the aggregates
An unusual rearrangement of Zofenopril, a new ACE inhibitor drug, under CID, MS, NMR and computational studies
No full textFunzionalizzazione del C-3’ delle cefalosporine Δ2 e Δ3
No full textViene descritta la reazione dei Δ3 – C3’ bromo derivati della cefalosporine con alcooli. Si ottengono 3’-acilossimetilcefalosporine con buone rese e senza isomerizzazione del doppio legame; la reazione è più lenta rispetto all'analoga trasformazione descritta per i derivati Δ2
Croton macrostachys, a plant used in traditional medicine: purgative and inflammatory activity
No full textCroton macrostachys seeds are widely used in Somalia as a purgative. in the present study, pharmacologic and chemical investigations confirm the laxative effect of the seeds and indicate the presence of phorbolesters. There appears to be no direct correlation between the phorbolester content and laxative effect
Studies related to cephalosporins. Part1. Solvolytic reactions of 3-bromomethyl cephems with alcohols and phenols
No full text3-Bromomethyl-3 cephems are solvolysed by alcohols, similarly to the Δ2 isomers. The yields are fairly good and this reaction represents a straightforward route to obntain 3-alcoxymethyl-3-cephems. Both 3-bromomethyl-2-cephems and 3-bromomethyl-3-isomers reactr with a variety of phenols under solvolytic conditions, giving only C-substitution products. This reaction represent the sole example of c-alkylation of phenols by an allylic bromide under such mild conditions
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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