1,720,973 research outputs found
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
CONDENSATION OF SUBSTITUTED 2-AMINOPYRIDINE WITH BETA-KETOCARBOXYLIC ESTERS: 4H-PYRIDO[1,2-a]PYRIMIDIN-4-0NES AND PYRIDIN-2-ONES
No full textPharmacokinetics of Tramadol and its Metabolites M1, M2 and M5 in Horses Following Intravenous, Immediate Release (Fasted/Fed) and Sustained Release Single Dose Administration
No full textTramadol (T) is a centrally acting analgesic structurally
related to codeine and morphine. This drug displays
a weak affinity for the m and d-opioid receptors, and
weaker affinity for the k-subtype; it also interferes with
the neuronal release and reuptake of serotonin and noradrenaline
in the descending inhibitory pathways. The
metabolism of this drug has been investigated in different
animals (rats, mice, Syrian hamsters, guinea pigs,
rabbits, and dogs) and humans; similar metabolites
are produced but in different amounts. The major
metabolic pathways involved in phase I metabolite production
(M1M5) are O-demethylation, N-demethylation,
and N,N-demethylation. The aim of the
current study is to evaluate the pharmacokinetic profile
of T in the horse, and its M1, M2, and M5 metabolites
after single-dose administration (5 mg/kg body weight
[BW]) by intravenous, sustained-release tablets and immediate-
release capsules. We also will investigate the potential
effects of fasting and feeding on bioavailability of
immediate-release capsules. The study design was divided
into four randomized phases. Twenty-four gelding
Italian trotter race horses were divided into four
groups (6 animals each) and administered T intravenously,
with T immediate-release capsules in a fasting
status, T immediate-release capsules in a feeding status,
and T sustained-release in fasting status. Blood samples
were collected at different times and analyzed by highpressure
liquid chromatography (HPLC) with fluorimetric
detection. The limit of quantification was 5
ng/ml for T, M1, and M2, and 10 ng/ml for M5. A
one-compartment model best fit the plasma concentrations
of T and M2 after all treatments. Unfortunately,
for M1 and M5, it was not always possible to fit plasma
curves because of very low and variable concentrations.
M2 was the main metabolite produced in the four different
treatments and its concentration was higher than the
concentration of T after sustained-release administration.
Conversely, M1, the main metabolite in humans,
and M5 seemed to be only marginally produced in the
horse. When T was administered in both fasted and
fed states, variations in some pharmacokinetic parameters
were not considered clinically significant. We concluded
that T could be administered in either a fasted
or a fed condition
Synthesis of 1,8-naphthyridine derivatives: potential antihypertensive agents. Part VIII
No full textA series of (ethoxycarbonylpiperazinyl)- and piperazinyl-1,8-naphthyridine derivatives, variously substituted, has been synthesized and pharmacologically investigated for anthihypertensive activity. Some of them exhibited a significant and prolonged decrease of the mean arterial pressure (MAP) on spontaneously hypertensive rats. On the basis of the pharmacological results, no structure-activity relationship can be deduced at this time. Moreover, the most active compound 4e, was investigated by means of in vitro pharmacological functional studies and in vivo, as a diuretic agent, to determine a possible mechanism of the antihypertensive activity, which results in a probably non-competitive antagonism against alpha(1), vascular adrenoceptors. This mechanism was also shown by the compounds 8 and 1
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
Synthesis and biological evaluation of 1,8-naphthyridin-4(1H)-on-3-carboxamide derivatives as new ligands of cannabinoid receptors
No full textCannabinoid receptors have been studied extensively in view of their potential functional role in several physiological and pathological processes. For this reason, the search for new potent, selective ligands for subtype CB receptors, CB(1) and CB(2), is still of great importance, in order to investigate their role in various physiological functions. The present study describes the synthesis and the biological properties of a series of 1,8-naphthyridine derivatives, characterised by the presence of some important structural requirements exhibited by other classes of cannabinoid ligands, such as an aliphatic or aromatic carboxamide group in position 3, and an alkyl or arylalkyl substituent in position 1. These compounds were assayed for binding both to the brain and to peripheral cannabinoid receptors (CB(1) and CB(2)). The results obtained indicate that the naphthyridine derivatives examined possess a greater affinity for the CB(2) receptor than for the CB(1) receptor. In particular, derivatives 6a and 7a possess an appreciable affinity for the CB(2) receptor, with K(i) values of 5.5 and 8.0 nM respectively; also compounds 4a, 5a and 8a exhibit a good CB(2) affinity, with K(i) values in the range of 10-44 nM. Furthermore, compounds 3g-i and 18 revealed a good CB(2) selectivity, with a CB(1)/CB(2) ratio >20
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
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