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Synthesis of 1,8 - naphthyridine derivatives: potential antihypertensive agents. Part VII
No full textA series of 2-(carbethoxypiperazinyl)- and 2-piperazinyl-1,8-naphthyridine derivatives, variously substituted, have been synthesized and pharmacologically investigated for their antihypertensive activity. Some of them exhibited a significant and prolonged decrease of the mean arterial pressure (MAP) on spontaneously hypertensive rats. For this series of compounds, on the basis of the pharmacological results obtained, no structure-activity relationship can be deduced at this time. Moreover, the most active and representative compounds 11b, 12a and 16b were investigated by means of in vitro pharmacological functional studies and in vivo, as diuretic agents, to determine a possible mechanism of the antihypertensive activity, which is unknown for the momen
Synthesis of 3- or 4-phenyl-1,8-naphthyridine derivatives and evaluation of antimycobacterial and antimicrobial activity
No full textA series of 3- or 4-phenyl-1,8-naphthyridine derivatives variously substituted in the positions 2, 6 and 7 were synthesized and evaluated for in vitro evaluation for their antimycobacterial activity as part of a TAACF TB screening program under the direction of the US National Institute of Health, NIAID division. Several compounds showed an interesting activity when tested at a concentration of 6.25 μg/ml against Mycobacterium tuberculosis H 37Rv and in particular compounds 2a, 4a,d, 8a,d and 8i, exhibit a % inhibition from 91 to 99. Among these, compounds 2a, 8a and 8d appeared to have a good activity with minimum inhibitory concentrations (MICs) of 6.25 μg/ml. On the basis of the biological results, the most effective substituent in position 2 or 7 seems to be the piperidinyl group. The introduction of a morpholinyl group either in position 2 or 7 of the heterocycle ring caused a decrease in activity. The 1,8-naphthyridine derivatives were also tested in vitro for their antimicrobial activity against Staphylococcus aureus as Gram-positive bacteria and Escherichia coli as Gram-negative bacteria
Stereoselective synthesis and beta-blocking activity of substituted (E)- and (Z)- 4(1H) - [1- (3 - alkylamino - 2 - hydroxypropyl) oximino - 2,3 - dihydro - 1,8 - naphthyridine. Potential antihypertensive agents. Part VI
No full textThe synthesis of R-(+)- and S-(-)-isomers of substituted (E)- and (Z)-4(1H)-[1-(3-alkylamino-2-hydroxypropyl)-oximino]-2,3-dihydro-1,8-naphthyridine, in enantiomeric pure form, is described. These compounds showed an interesting beta-blocking activity. Generally, the (S)-enantiomers possess a slighthly higher affinity for beta receptors than the (R)-enantiomers
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Unusual nitration of substituted 7-amino-1,8-naphthyridine in the synthesis of compounds with antiplatelet activity
No full textSeveral 1,8-naphthyridine derivatives have been diazotizated to obtain the corresponding hydroxy derivatives or mixture of hydroxy and hydroxy nitro derivatives. The respective amounts of hydroxy and hydroxy nitro derivatives depends on the nature of the substituents, on their position on the naphthyridine nucleus, on the amount of sodium nitrite and on the reaction temperature. A study of the electronic density of some molecules suggests a possible explanation of the effects induced by the nature of the substituents and of their position. Some of the compounds were tested for their ability to inhibit human platelet aggregation in vitro induced by arachidonic acid. Only compound 26 showed interesting antiplatelet activit
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