1,720,960 research outputs found
Synthesis of novel derivatives of resveratrol and screening for potential cancer chemopreventive activities
No full textResveratrol (trans-3,4’,5-trihydroxystilbene) has attracted the attention of the biomedical researchers because of its beneficial physiological effects it produces. Positive effects of resveratrol has been observed in the field of cardiovascular diseases and neurodegenerative disorders. It has been also identified as a potent cancer chemopreventive agent in assays representing the three major stages of carcinogenesis (i.e. tumor initiation, promotion and progression). We have synthesized a variety of Resveratrol analogues by chemical modification of the parent trihydroxy stilbene skeleton. The compounds were screened for cancer chemopreventive potential using a series of bioassays relevant for the prevention of carcinogenesis in humans (inhibition of cytochrome P450 1A; determination of NAD(P)H:quinone reductase activity; scavenging of radicals; inhibition of cyclooxygenase activity; inhibition of NO synthase; antiestrogenic and estrogenic activity)
Synthesis of resveratrol derivatives and in vitro screening for potential cancer chemopreventive activities
No full textNew resveratrol (trans-3,4’,5-trihydroxystilbene) analogs were synthesized and screened for their in vitro cancer chemopreventive potential using various bioassays relevant for the prevention of carcinogenesis in humans: Two assays to detect modulators of carcinogen metabolism (Cyp1A inhibition; determination of NAD(P)H/quinone reductase (QR) activity), three assays to identify radical scavenging and antioxidant properties (DPPH, ORAC, superoxide anion radicals in differentiated HL-60 cells), four assays to determine anti-inflammatory and anti-hormonal effects (iNOS, Cox-1 and aromatase inhibition, anti-estrogenic potential). 3,40,5-Tri-O-methyl resveratrol 1a was about seven-fold more active than resveratrol in inhibiting Cyp1A activity, it was a potent inducer of QR activity, and it showed pure anti-estrogenic activity (whereas resveratrol is a known mixed estrogen (ant)agonist with both estrogenic and anti-estrogenic properties). Dual estrogen ant-/agonist activity was restored in the mono-O-benzyl-substituted derivatives 4b (40-O-benzyl resveratrol) and 5b (3-O-benzylresveratrol). With respect to aromatase inhibition (Cyp19), which provided the highest number of actives, the benzyl-substituted series was more potent than the methyl-substituted derivatives of resveratrol, and 3-O-benzyl resveratrol 5b was about eightfold more active than resveratrol. Overall,
21 3,40,5-tri-O-pivaloyl resveratrol oxide 7c was identified as a potent inducer of phase 2 enzymes
22 concomitant with inhibition of LPS-mediated iNOS induction
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
Brown seaweed polyphenols as novel antioxidants for better health and food quality
No full textIn the Far East and Pacific, there is a long tradition of consuming seaweeds as sea vegetables, while in western countries the principal use of seaweeds is as source of phycocolloids (eg. thickening and gelling agents for agro-food industry). In Asia, recent epidemiological studies have demonstrated that regular consumption of seaweeds might be related to a reduction of prostate, colorectal and breast cancer risk. Researches carried out on natural products from seaweeds lead to the identification of a variety of antioxidant compounds, among which polyphenolic compounds. Brown seaweeds are particularly rich in polyphenols: from 5 to 15 % of the dry weight. These compounds are made from phloroglucinol units, connected by aryl/aryl bonds (fucols), by aryl ether bonds (phlorethols) or both (fucophlorethols). Some of them contain one additional hydroxyl group at each second ring and a regular sequence of para- and ortho- positioned ether links (fuhalols and pseudofuhalols). In comparison with terrestrial plants, little is known about the antioxidant activity of seaweed polyphenols.
The main objectives of the SEAHEALTH project carried out with financial support from the Commission of the European Communities (“Quality of Life and Management of Living Resources” RTD programme) is to demonstrate benefits of seaweeds antioxidant substances on human health (prevention of atherosclerosis and cancer) and food quality.
This paper presents the results obtained during the first half of the SEAHEALTH project. In a first step, extraction/purification process of seaweed antioxidants was optimised. For comparative reasons and to establish a superior method for polyhenols determination, two quantitative methods were evaluated: Folin Ciocalteu’s and DMBA (2,4-dimethoxybenzaldehyde). Qualitative analysis were performed by 1H NMR and HPLC-MS. Size exclusion chromatography (SEC) was evaluated as a method to separate polyhenols according to their molecular weight. An important antioxidant and scavenging activity of some of the extracts was observed in vitro (DPPH and ORAC tests). The capacity of seaweed extracts to scavenge superoxide anion radical generated during the oxidation of xanthine to uric acid in the presence of xanthine oxidase was measured. The influence of the extracts on carcinogen metabolism was assessed by measuring inhibition of phase I enzyme (cytochrome P450 Cp1A) activity. The anti-inflammatory and the anti-hormonal effects of the extracts were evaluated by measuring inhibition of cyclooxygenase and aromatase activity, respectively. Acute toxicological studies were performed on mice and rats by oral and intraperitoneal routes with two different oral doses of seaweed extracts. Finally, some food products (fruit juices and yoghourts) were formulated from seaweed extracts. Results showed that antioxidant activity was still detectable in formulated products
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
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