1,720,957 research outputs found
IN VITRO STUDIES ON CYANIDIN PROTECTION AGAINST DOXORUBICIN CARDIOMYOCYTE CYTOTOXICITY AND ANTICANCER ACTIVITY
Get PDFMitochondrial reactive oxygen species (ROS) are recognized for their role in several health related problems when produced at excessively high concentrations. Due to their potent antioxidant activity and potential mitochondriotropic behavior, the anthocyanidins may have the potential to lower mitochondrial ROS levels. Nevertheless, the effect of anthocyanidins remains overlooked due to their presumed low stability and bioavailability. In addition, this instability has lead to a general belief that the phenolic degradation products, protocatechuic acid (PCA) and phloroglucinaldehye (PGA), exert the bioactivity rather than the parent compound.
In this work, doxorubicin-induced cytotoxicity in differentiated H9c2 cardiomyocytes was initially established as a model in which the mitochondrial antioxidant activity of the selected flavonoids would be examined. First, we delineated the mechanisms by which doxorubicin affected H9c2 cell survival and mitochondrial function. The results showed that the early effects of doxorubicin on mitochondrial superoxide generation led to a delayed effect on cell survival. Using this model, we then revealed the protective ability of cyanidin against doxorubicin-induced cytological damage, showing protection to mitochondria. While cyanidin co-incubation with doxorubicin did not show protection when cell survival was assessed after 24 h, it gave delayed protection after a further 24 h drug-free period. Using the delayed protection model, we also showed that cyanidin had greater bioactivity over other flavonoids tested (quercetin, catechin and cyanidin-3-glucoside (C3G)). The protection by cyanidin also exceeded that of its degradation products (PCA and PGA), suggesting that the parent compound has additional bioactivity. The cytoprotective ability of the flavonoids was related to their ability to lower mitochondrial superoxide at early time points, with cyanidin being the most effective. Experiments on doxorubicin cytotoxicity to HepG2 (liver cancer) and K562 (erythroleukemia) cells showed no protective effect with cyanidin. These results suggest cyanidin protects cardiomyocytes but does not interfere with the cytotoxic activity of doxorubicin in the cancer cell lines.
Investigations on the degradation of cyanidin in physiological media, UV-vis, HPLC and MS analytical techniques provided evidence that cyanidin does not degrade immediately to PCA and PGA. Instead, intermediate compounds (hemiketal and chalcone) survived for sufficient periods to exert putative bioactivity. Studies on the influence of different media on the degradation of cyanidin showed that the stability in human serum was significantly higher (t½ 43.2 min at room temperature, 22 ¬± 1°C) compared to phosphate buffered saline and Dulbecco’s Modified Eagle’s Medium with and without 10% fetal bovine serum (t½ 10.2-32.6 min).
In conclusion, using differentiated H9c2 cells, our results show an ability of cyanidin to survive long enough in cell culture media, and presumably intracellularly, to exert cytoprotection against doxorubicin which exceeded that of other flavonoids (quercetin, catechin, C3G) and its degradation products (PCA and PGA). The results present cyanidin as a possible antioxidant choice to use in clinical practice to protect the heart from the mitochondrial toxicity of doxorubicin and warrants investigation into this possible therapeutic application
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
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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