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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
Efeitos das chalconas sobre propriedades oxidativas de mitocôndrias isoladas de fígado de rato
Get PDFOrientadora : Profª Drª Maria Eliane Merlin RochaDissertação (mestrado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ciências-Bioquímica. Defesa: Curitiba, 02/2014Inclui referênciasResumo: Os flavonoides têm sido utilizados no tratamento de diversas patologias como alergias, infecções virais, úlceras e câncer. Dentro deste grupo de compostos encontram-se as chalconas, presentes no lúpulo e na maçã, e que possuem várias atividades biológicas conhecidas como: antioxidante, imunomoduladora, anti-inflamatória, antibacteriana, antifúngica, antitumoral entre outras. Além disso, sabe-se que a chalcona (1,3-difenil 2-propenona) induz a morte celular por apoptose utilizando via intrínseca em células tumorais de bexiga. Tamiello et al. (2013) verificaram que as nitrochalconas reduzem a viabilidade de células de hepatocarcinoma humano (HepG2) de forma mais intensa que o observado com a chalcona, contudo, os efeitos da chalcona, da 3-nitrochalcona e da 4-nitrochalcona sobre o metabolismo mitocondrial hepático não são bem conhecidos. Sabendo-se do papel central das mitocôndrias na provisão de energia celular e no mecanismo de indução de morte celular por apoptose por via intrínseca e da necessidade de busca por novas moléculas anticarcinogênicas que sejam mais efetivas, porém com maior seletividade contra células tumorais, neste trabalho foram avaliados os efeitos da chalcona (20-200 µmol.L-1), da 3-nitrochalcona (20 µmol.L-1) e da 4-nitrochalcona (20 µmol.L-1) sobre mitocôndrias isoladas de fígado de rato. Os experimentos polarográficos utlizando a chalcona mostraram que houve redução da velocidade respiratória durante o estado 3 de ~26, ~21, ~34 and ~75% nas doses de 20, 50, 100 e 200 µmol.L-1, respectivamente. Como consequência, os valores de coeficiente de controle respiratório (CCR) foram reduzidos de forma similar. A 3-nitrochalcona (20 µmol.L-1) diminuiu o CCR em ~10% e a 4-nitrochalcona (20 µmol.L-1) reduziu a velocidade respiratória durante o estado 3 e o CCR em ~15%. Os resultados sugerem que a adição do grupamento nitro nas posições 3 ou 4 da estrutura da chalcona diminui a ação do flavonoide sobre a respiração mitochondrial. A chalcona inibiu a atividade da NADH oxidase em ~25, ~56, ~78 and ~89%, enquanto, a inibição da succinato oxidase foi de ~30, ~47, ~57 and ~64% nas doses de 20, 50, 100 and 200 µmol.L-1, respectivamente. A análise das atividades dos complexos enzimáticos demonstrou que a chalcona não inibe outras atividades de enzimas da cadeia respiratória. A chalcona inibiu discretamente a atividade da catalase (~10%), e não afetou a atividade da superóxido dismutase e nem os níveis de H2O2 durante o estado 3 e 4 da respiração mitocondrial. In vitro a chalcona foi capaz de sequestrar radical superóxido. Os resultados acima sugerem que a chalcona reduz a respiração mitocondrial possivelmente por afetar o transporte de elétrons na cadeia respiratória através de reações de oxido-redução diretas com seus componentes sem, contudo, alterar significativamente atividades de enzimas antioxidantes ou níveis de H2O2.Abstract: Flavonoids have been used in the treatment of various diseases such as allergies, viral infections, ulcers and cancer. Within this group are chalcones, that could be found in hops and apples, and have several known biological activities such as antioxidant, immunomodulatory, anti-inflammatory, antibacterial, antifungal, antitumor, among others. Furthermore, it is known that the chalcone (1,3-diphenyl-2-propen-1-ones) induces apoptotic cell death using the intrinsic pathway of tumor cells in the bladder. Tamiello et al. (2013) found that nitrochalconas reduce the viability of human hepatocellular carcinoma cells (HepG2) more intense than that observed with chalcone, however, the effects of chalcone, the 3-nitrochalcona and 4-nitrochalcona on hepatic mitochondrial metabolism are not well known. Given the central role of mitochondria in the provision of cellular energy and the induction of cell death by apoptosis by the intrinsic pathway and the need to search for new anticarcinogenic molecules more effectives but with increased selectivity against tumor cells, this work evaluated the effects of chalcone (20-200 µmol.L-1) of 3-nitrochalcona (20 µmol.L-1) and 4-nitrochalcona (20 µmol.L-1) on mitochondria isolated from rat liver. The polarographic experiments using the chalcone showed that the reduction in respiratory rate during state 3 of ~26, ~21, ~34 and ~75% at doses of 20, 50, 100 and 200 µmol.L-1, respectively. Consequently, the respiratory control coefficient (RCC) were similarly reduced. The 3-nitrochalcona (20 µmol.L-1) decreased the CCR in ~10% and 4-nitrochalcona (20 µmol.L-1) decreased respiration rate during state 3 and CCR at ~15%. The results suggest that the addition of the nitro group in position 3 or 4 of a chalcone structure reduces the action of this flavonoid on the mitochondrial respiration. The chalcone inhibited NADH oxidase activity of ~25, ~56, ~78 and ~89%, whereas inhibition of succinate oxidase was ~30 , ~47, ~57 and ~64% at doses of 20, 50, 100 and 200 µmol.L-1, respectively. The analysis of the activities of enzyme complexes showed that chalcone does not inhibit others respiratory chain enzymes. The chalcone inhibited slightly the activity of catalase (~10 %), and did not affect the activity of superoxide dismutase nor the levels of H2O2 during state 3 and 4 of mitochondrial respiration. In vitro chalcone was able to sequester superoxide. The results suggest that chalcone reduces mitochondrial respiration, possibly by affecting the transport of electrons in the respiratory chain through direct reactions with redox components, but without significantly altering antioxidant enzyme activities or levels of H2O2
Efeitos citotóxicos da 4'-hidroxichalcona e da isoliquiritigenina em células de neublastoma humano
Get PDFOrientadora: Profª. Drª. Maria Eliane Merlin RochaCoorientadores: Profª. Dra. Sheila M. B. Winnischofer, Dr. Paul Keneth Witting - University of SydneyTese (doutorado) - Universidade Federal do Paraná, Setor de Ciências Biológicas, Programa de Pós-Graduação em Ciências - Bioquímica. Defesa : Curitiba, 27/06/2018Inclui referênciasResumo: O neuroblastoma é um câncer infantil com alta mortalidade. As hidroxichalconas têm recebido atenção considerável devido às suas atividades citotóxicas em células tumorais. Deste modo, o objetivo do presente estudo foi caracterizar a citotoxicidade das hidroxichalconas, 4'-hidroxichalcona e isoliquiritigenina (4,2',4'-trihidroxi-chalcona; ISL) em neuroblastoma utilizando um modelo in vitro de células SH-SY5Y. A incubação das células SHSY5Y cultivadas com 4HC (10-60 ?M) por 24 h diminuiu a confluência, a atividade metabólica e os níveis de ATP intracelulares em relação ao controle. Com base nos resultados, a toxicidade celular induzida por 4HC provavelmente está relacionado com as disfunções mitocondriais, como: inibição da respiração mitocondrial, despolarização do potencial de membrana mitocondrial e alterações morfológicas. Além disso, a perda de viabilidade celular foi acompanhada principalmente pelo aumento da exposição de fosfatidilserina na superfície das células, sugerindo que a 4HC poderia induzir a via intrínseca da apoptose em células SH-SY5Y. Além disso, o tratamento com 4HC inibiu a migração/proliferação celular de SH-SY5Y e induziu mudanças significativas na progressão do ciclo celular. A incubação das células SH-SY5Y com 10-100 ?M de ISL (24 h) diminuiu a confluência e os níveis de ATP intracelular em relação ao controle; o inibidor da necroptose necrostatina-1 restaurou os níveis de ATP. A citotoxicidade mediada por ISL não envolveu ativação das caspases 3/7 ou aumento da exposição de fosfatidilserina na superfície das células, indicando que a morte celular foi independente da via clássica da apoptose. O tratamento com ISL inibiu a proliferação/migração celular e modificou a progressão do ciclo celular SH-SY5Y. Nossos resultados mostram que ambas as hidroxichalconas, 4HC e ISL, têm efeitos citotóxicos contra a linhagem celular de neuroblastoma humano SH-SY5Y apresentando valores de EC50 de 21,5 ± 3,4 ?M para 4HC e 25,4 ± 1,4 ?M para ISL. No entanto, os efeitos do 4HC nas células do neuroblastoma estão associados com a disfunção mitocondrial e sugerem morte celular por apoptose enquanto que a atividade de ISL em células de neuroblastoma envolve a morte celular possivelmente por necroptose. Palavras-chave: hidroxichalcona; neuroblastoma; SH-SY5Y; necroptose; apoptose; disfunção mitocondrial. Neuroblastoma is a childhood cancer with high mortality.Abstract: Hydroxychalcones have received considerable attention because of their cytotoxic activities on cancer cells. Thus, the aim of the present study was to characterize the cytotoxicity of the hydroxychalcones, 4'-hydroxychalcone and isoliquiritigenin (4,2',4'-trihydroxychalcone; ISL) to neuroblastoma using an in vitro model of SH-SY5Y cells. Incubation of cultured SHSY5Y cells with 4HC (10-60 ?M) for 24 h decreased cell confluency, cellular metabolic activity and depleted intracellular ATP relative to the vehicle-treated control. The mechanism of 4HC-induced cell toxicity likely involves mitochondria dysfunctional as judged by inhibition of mitochondrial respiration, depolarization of mitochondria membrane potential and morphological alterations. Furthermore, loss of cell viability was accompanied mainly by increase of phosphatidylserine exposure on the surface of cells, suggesting that the 4HC may induce the intrinsic pathway of apoptosis in SH-SY5Y cells. In addition, 4HC treatment inhibited SH-SY5Y cell migration/proliferation in a scratch assay and induced significant changes in the cell cycle progression. Incubation of SH-SY5Y cells with 10-100 ?M ISL (24 h) decreased confluency and intracellular ATP relative to control; the necroptosis inhibitor necrostatin-1 restored ATP levels. ISL-mediated cytoxicity did not involve caspase 3/7 activation or increase of phosphatidylserine exposure on the surface of cells, indicating that cell death was apoptosis independent. ISL treatment inhibited cell proliferation/migration and arrested SH-SY5Y cell cycle transition. Our results showed that both of hydroxychalcones, 4HC and ISL, have cytotoxic effects against human neuroblastoma cell line SH-SY5Y with EC50 values of 21.5 ± 3,4 ?M for 4HC and 25.4 ± 1,4 ?M for ISL. However, 4HC effects on neuroblastoma cells are associated with mitochondrial dysfunctional and it suggest cell death by apoptosis. Whilst, activity of ISL on neuroblastoma cells involves cell death possibly via a necroptotic pathwayx. Keywords: hydroxychalcona; neuroblastoma; SH-SY5Y; necroptosis; apoptosis; mitochondrial dysfunction
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
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