1,720,963 research outputs found
Genomic study, phytochemical characterization, and antiproliferative activity of two different genotypes of Jatropha curcas L. obtained by a breeding program
Full text linkJatropha curcas (Euphorbiaceaefamily) is a multipurpose plant with considerable potential in biodiesel production, and in cosmetic and medicinal uses. The part of J. curcas usually used is the oil obtained from its seeds, whereas the leaves generally represent the waste material. The aim of this study was to characterize the composition and to preliminary investigate the biological activity of J. curcas leaves obtained from plants by a breeding program. To describe genomic structure, molecular markers were applied. For biological study, two genotypes (JA and JB) that are genetically divergent were selected by cluster analysis. A phytochemical analysis was carried out to characterize the chemical composition of the extracts, which resulted rich in biologically active compounds, whereas toxic phorbol esters were absent. Biological assays showed an antiproliferative effect on the Buffalo normal rat liver cell line (BRL-3A), with genotype B being more potent than that of the counterpart (JA). The purified compounds isolated did not show antiproliferative activity, suggesting that the effect observed was due to the phytocomplex and should involve several secondary metabolites. This study highlights that a plant of the same genus and same species that has been cultivated in the same soil and climatic conditions can be characterized by a high variability. This is what makes research in pharmacognosya complex process
Microbiota-Derived Natural Products Targeting Cancer Stem Cells: Inside the Gut Pharma Factory
Full text linkCancer stem cells (CSCs) have drawn much attention as important tumour-initiating cells that may also be crucial for recurrence after chemotherapy. Although the activity of CSCs in various forms of cancer is complex and yet to be fully elucidated, opportunities for therapies targeting CSCs exist. CSCs are molecularly distinct from bulk tumour cells, so they can be targeted by exploiting their signature molecular pathways. Inhibiting stemness has the potential to reduce the risk posed by CSCs by limiting or eliminating their capacity for tumorigenesis, proliferation, metastasis, and recurrence. Here, we briefly described the role of CSCs in tumour biology, the mechanisms involved in CSC therapy resistance, and the role of the gut microbiota in cancer development and treatment, to then review and discuss the current advances in the discovery of microbiota-derived natural compounds targeting CSCs. Collectively, our overview suggests that dietary intervention, toward the production of those identified microbial metabolites capable of suppressing CSC properties, is a promising approach to support standard chemotherapy
ANTIBACTERIAL ACTIVITY OF NEW β-LACTAM COMPOUND
Full text linkA new β-lactam molecule A1 was synthesized and formulated to introduce an innovative solution in order to circumvent the bacterial resistance and their defenses against antibiotics. This innovative molecule was tested towards representative Gram positive and Gram negative strains of antibiotic-resistant pathogenic bacteria to evaluate its antibacterial activity and to analyze the action spectrum and the antibacterial effectiveness. Results showed that the new compound A1 was synthesized with a yield of 55% and demonstrated the antimicrobial activity against all tested bacteria, except Pseudomonas aeruginosa, and all Gram-positive bacteria were more sensitive with a good antimicrobial activity. Moreover, as the determined MIC90, both strains of the Streptococcus genus were inhibited at a concentration of 16 μg/ml of the compound A1, while Staphylococcus aureus resulted sensitive to an inhibitory concentration of 64 μg/ml. The Gram-negative bacteria, instead, required an inhibitory concentration of 64 μg/ml for Escherichia coli and 128 μg/ml for Klebsiella pneumoniae. In conclusion, compound A1 is a promising molecule to develop a new class of safe and active antibiotics, with a predicted good inhibitory capacity not only against Gram positive, but also Gram negative microorganisms. Keywords: β-lactam compoun
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
Metagenomic monitoring of soil bacterial community after the construction of a crude oil flowline
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