1,720,958 research outputs found
Aislamiento biodirigido y caracterización de compuestos anti-helicobacter pylori a partir de una planta usada en la medicina tradicional peruana
Full text linkCordia lutea Lam (Flor de Overo) es una planta usada en la medicina tradicional Peruana como remedio para el tratamiento de desórdenes gastrointestinales, hepatitis y dolor de riñones. El fraccionamiento biodirigido del extracto etanólico obtenido a partir de las flores, utilizando un ensayo de microdilución en caldo, permitió realizar el aislamiento de tres fracciones purificadas: SC1 (2), SC2 (2) y SC3 (2). Estas fracciones presentaron una concentración mínima inhibitoria (CMI) de 31.3 µg/mL frente a una cepa de referencia de Helicobacter pylori (CIP 193995). Se evaluó la citotoxicidad de SC1 (2), SC2 (2) and SC3 (2) frente a macrófagos murinos (RAW 264.7). Las tres fracciones mostraron una elevada toxicidad en término de concentración inhibitoria media (CI50= 4.2±2.5, 3.8±1.5 y 8.8±3.3, respectivamente). Cada una de las fracciones purificadas SC1 (2), SC2 (2) y SC3 (2) estuvieron conformadas por una mezcla de dos saponinas esteroidales. El análisis realizado mediante cromatografía líquida acoplada a espectrometría de masas, en conjunto con métodos espectroscópicos (RMN) permitió la identificación de los compuestos presentes en cada una de las fracciones. Los seis compuestos identificados presentaron un núcleo esteroidal en común (4α,14α-dimetilesterol), por primera vez descrito para C. lutea
Caractérisation des métabolites secondaires responsables de l'activité anti-Helicobacter pylori d'une plante médicinale péruvienne Cordia lutea Lam. (Boraginaceae)
No full textCordia lutea Lam. (Flor de Overo) est une plante utilisée en médecine traditionnelle péruvienne pour le traitement des troubles gastro-intestinaux, des hépatites et des douleurs
rénales. Onze composés ont été isolés à partir de l'extrait éthanolique des fleurs de cette plante médicinale sur la base d'un fractionnement bioguidé. Dix de ces composés
(cordiasecosides A-J), représentent les premiers exemples de 9,10-seco-29-norcycloartane glycosides. Leurs structures ont été déterminées par des analyses de données RMN et MS
ainsi que des analyses cristallographiques aux rayons X. Ces composés ont montré une activité in vitro anti-Helicobacter pylori significative et aucune activité contre
Escherichia coli ou Pseudomonas aeruginosa. Une activité significative a été observée pour les cordiasecosides E et F contre Staphylococcus aureus. Tous les composés présentent
une faible cytotoxicité contre les cellules RAW 264,7. Les activités antileishmaniales et antiplasmodiales in vitro des cordiasecosides A à F ont également été évaluées. Le
présent travail de recherche comprend aussi l'isolement de deux composés précédemment décrits dans la littérature : l'acide isorinique et la quercétine 3-robinobioside. Enfin,
l'étude botanique et chimique de différents lots de matériel végétal achetés sur différents marchés a également été réalisée, dans le but d'évaluer la variabilité de la drogue
et de proposer des pistes pour contrôler sa qualité.Cordia lutea Lam. (Flor de Overo) is a plant used in Peruvian traditional medicine as a remedy for the treatment of gastrointestinal disorders, hepatitis and kidney pain. Eleven compounds were isolated from the ethanol extract of the flowers of this medicinal plant on the basis of bioassay-guided fractionation. Ten of these compounds (cordiasecosides A-J), represent the first examples of 9,10-seco-29-norcycloartane glycosides. Their structures were determined by the application of NMR and MS data analysis together with X-ray crystallographic analyses. These compounds showed significant in vitro anti-Helicobacter pylori activity, and no activity against Escherichia coli or Pseudomonas aeruginosa. Significant activity was observed for cordiasecosides E and F against Staphylococcus aureus. All compounds displayed weak cytotoxicity against RAW 264.7 cells. The in vitro antileishmanial and antiplasmodial activities of cordiasecosides A -F were also evaluated. This research work also includes the isolation of two compounds previously described in the literature: isorinic acid and quercetin 3-robinobioside. Finally, the botanical and chemical study of different batches of plant material purchased from different markets was also carried out, with the aim of assessing the variability of the drug and proposing ways to control its quality
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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