1,720,961 research outputs found
Leaf extract of Annonaceae: citotoxicity, íon flux and tumor markers in hepatic carcinogenic cells
No full textO carcinoma hepatocelular é o mais frequente câncer primário do fígado e já se tornou a quinta neoplasia mais comum no mundo e a segunda causa de óbitos relatados por câncer. Estima-se que 2/3 das neoplasias humanas poderiam ser prevenidos pela modificação do estilo de vida, incluindo a dieta. Estudos farmacológicos intensificaram-se nos últimos anos com plantas da família Annonaceae, cujo interesse científico está nas acetogeninas, uma classe de compostos derivados de ácidos graxos com forte atividade antitumoral. Os experimentos foram conduzidos no Laboratório de Infectologia Molecular Animal, do Departamento de Bioquímica e Biologia Molecular, na Universidade Federal de Viçosa, para avaliar in vitro as propriedades antitumorais de extratos foliares de 11 Anonáceas (9 espécies de 4 gêneros). Para isso, células tumorais hepáticas humanas da linhagem HepG2 (ATCC HB-8065 ) foram expostas a três concentrações dos extratos foliares de Anonáceas e do quimioterápico 5- Fluoruracil (5-FLU), em três períodos de tempo (24, 48 e 72 h), com análise espectrofotométrica da viabilidade celular pela metodologia do corante vermelho neutro. Foram conduzidos ensaios para avaliar o efeito dos extratos vegetais e do quimioterápico sobre o fluxo químico celular no meio de cultura durante os cultivos através da análise por Espectrometria de Emissão Atômica de diferentes especies químicas, e sobre o metabolismo e integridade celular, através da análise de marcadores tumorais e intermediários metabólicos. Todos os ensaios induziram à morte celular, com resultados distintos entre plantas da mesma espécie, com até 100% de citotoxicidade, sendo que nove Anonáceas exibiram efeito citotóxico com até 1/8 da concentração daquela utilizada para o quimioterápico 5-FLU. Nenhum dos ensaios com extratos foliares exibiu retomada da proliferação celular após 48 ou 72 h, o que foi verificado para os cultivos com o quimioterápico, clara evidência de quimiorresistência tumoral. O mecanismo de morte celular por apoptose foi confirmado através da citometria de fluxo para dois dos extratos escolhidos, incluindo 5-FLU. Não houve um padrão no efeito dos extratos sobre o fluxo de íons ou dos marcadores tumorais durante os cultivos das células hepatocarcinogênicas, que se mostrou variável dentro da espécie ou entre elas, ou dentro de um mesmo gênero ou entre eles, com interferência na absorção de alguns íons especialmente, Ca, Na, P, S e depleção intracelular total de outros (Se, Zn) para alguns dos tratamentos. Marcadores bioquímicos como aspartato aminotransferase (AST), alanina aminotransferase (ALT) e lactato desidrogenase (LDH) tiveram seus níveis elevados para alguns dos extratos utilizados, incluindo 5-FLU, resultado coincidente com a redução na absorção da glicose pelos hepatócitos tumorais, indícios da alteração no metabolismo e integridade celular.The hepatocellular carcinoma is the most common primary liver cancer and has become the fifth most common cancer worldwide and the second leading cause of cancer deaths reported. It is estimated that two thirds of human cancers could be prevented by changes in lifestyle, including diet. Pharmacological studies have intensified in recent years with the Annonaceae plant family, whose scientific interest is in the acetogenins, a class of compounds derived from fatty acids with strong antitumor activity. The experiments were conducted at the Laboratory of Molecular Animal Infectious Diseases, Department of Biochemistry and Molecular Biology, Federal University of Viçosa, to evaluate the in vitro antitumor properties of leaf extracts of 11 annonaceae (9 species of 4 genera). For this, human liver cancer cells HepG2 line (ATCC HB-8065 ) were exposed to three different concentrations of leaf extracts of Annonaceae and of the chemotherapeutic 5-fluorouracil (5-flu) in three time periods (24, 48 and 72 h), with spectrophotometric analysis of cell viability by the neutral red dye method. Assays were conducted to evaluate the effect of plant extracts and chemotherapeutic chemical flow cell on the culture medium during the cultivation by atomic emission spectrometry analysis of different chemical species, and the cellular integrity and metabolism, by analysis of tumor markers and metabolic intermediates. All assays induced cell death, with results between different plants of the same species, with up to 100% cytotoxicity, nine annonacea exhibited cytotoxic effect up to one eighth of the concentration of that used for the chemotherapeutic 5-flu. None of the trials with leaf extracts exhibited recovery of cell proliferation after 48 or 72 h, which was observed in cultures with chemotherapy, clear evidence of tumor chemoresistance. The mechanism of cell death by apoptosis was confirmed by flow cytometry for two extracts selected, including 5-flu. There was no pattern in the effect of the extracts on the flow of ions or of tumor markers during the cultivation of hepatic ocarcinogenic cells, which was variable within species or between or within the same genus or between them, interfering with the absorption of especially some ions, Ca, Na, P, S, and total depletion of other intracellular (Se, Zn) for some treatments. Biochemical markers such as aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) had their elevated levels for some of the extracts used, including 5-flu coincident result with a reduction in glucose uptake by tumor hepatocytes, evidence of changes in metabolism and cellular integrity.Fundação de Amparo a Pesquisa do Estado de Minas Gerai
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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