1,720,954 research outputs found
Efecto de la dehidroepiandrosterona en las proteínas involucradas en la transición epitelio-mesénquima en células de cáncer de mama
Get PDFBreast cancer is one of the most common neoplasia in the world and is the leading cause of cancer death in women in Mexico. Its high mortality is due mainly to its great metastatic capacity, which is associated with epithelial-mesenchymal transition (EMT). During this process, a decrease in the expression of epithelial proteins and an increase of mesenchymal proteins is observed. On the other hand, it has been shown that dehydroepiandrosterone (DHEA), the most abundant steroid in human plasm, inhibits breast cancer cells migration; however, the mechanisms involved in this process have not yet been determined. In this study, the effect of DHEA on the expression of some proteins involved in the EMT, such as E-cadherin (epithelial), N-cadherin and vimentin (mesenchymal) was evaluated in the breast cancer cells MDA-MB-231 (mesenchymal phenotype, invasive and metastatic) and MCF-7 (epithelial phenotype, non-invasive and non-metastatic) using immunoassay and immunofluorescence, also the effect of DHEA on tumor growth in a xenograft model in vivo with nu-/nu- mice was evaluated. Our results showed that DHEA increased the expression of E-cadherin and decreased Ncadherin and vimentin in MDA-MB-231 cells; however, in MCF-7 cells it had no effect, suggesting that DHEA reverses the mesenchymal phenotype, but does not affect epithelial. In the in vivo model, it was observed a decrease in tumor size when DHEA was administered a week before and at the same time that inoculation with MDA-MB-231 cells. In conclusion, DHEA may be useful in the treatment of breast cancer that has a mesenchymal and metastatic phenotype.El cáncer de mama es una de las neoplasias más frecuentes en todo el mundo y constituye la primera causa de muerte por cáncer en mujeres en México. Su elevada mortalidad se debe principalmente a su gran capacidad metastásica, la cual se asocia a la transición epitelio-mesénquima (TEM). Durante este proceso, se disminuye la expresión de proteínas epiteliales y se incrementan las mesenquimales. Por otro lado, se ha demostrado que la dehidroepiandrosterona (DHEA), el esteroide más abundante en el plasma humano, inhibe la migración de células de cáncer de mama; sin embargo, los mecanismos que rigen este proceso aún no se han determinado. En este trabajo se evaluó el efecto de la DHEA en la expresión de algunas proteínas involucradas en la TEM, como la E-caderina (epitelial), la N-caderina y la vimentina (mesenquimales) en las células de cáncer de mama MDA-MB-231 (fenotipo mesenquimal, invasivas y metastásicas) y MCF-7 (fenotipo epitelial, no invasivas, no metastásicas) mediante el uso de inmunoanálisis e inmunofluorescencia. También se evaluó el efecto de la DHEA en el crecimiento de tumores de células MDA-MB-231 en un modelo de xenotransplante in vivo con ratones nu-/nu-. Nuestros resultados mostraron que la DHEA aumentó la expresión de la E-caderina y disminuyó la de la N-caderina y la vimentina en las células MDA-MB-231; sin embargo, en las células MCF-7 no tuvo ningún efecto, lo que sugiere que la DHEA revierte el fenotipo mesenquimal, pero no afecta al epitelial. En el modelo in vivo se observó una disminución en el tamaño de los tumores cuando la DHEA se administró una semana antes y al mismo tiempo en que se realizó la inoculación con las células de mama. En conclusión, la DHEA podría ser útil como un agente en el tratamiento contra el cáncer de mama que presenta un fenotipo mesenquimal y metastásico
Mecanismo de acción de la dehidroepiandrosterona en la transición mesénquima-epitelio en célula de cáncer de mama MDA-MB-231
Get PDFEl cáncer es una de las principales causas de muerte en todo el mundo, siendo el cáncer de mama la primera causa en mujeres, por lo que esta tesis contribuirá a dar un mejor y eficaz tratamiento contra el cáncer de mama. La dehidroepiandrosterona (DHEA) es una hormona esteroide adrenal y está presente en una concentración más alta que cualquier otra hormona en el plasma humano. Se ha observado que la DHEA inhibe la proliferación y la migración de las células de cáncer de mama, y modifica la expresión de proteínas implicadas en la transición epitelio-mesénquima (TEM). Sin embargo, los mecanismos implicados en estos efectos no se comprenden completamente. Por lo que es importante estudiar este mecanismo por el cual la DHEA tiene estos efectos sobre el cáncer de mama para poder utilizarla en el tratamiento de dicha enfermedad. Los efectos de la DHEA sobre la línea celular de cáncer de mama triple negativo MDA-MB231 podrían producirse por la unión de ésta a los RTK y la señalización a través de las vías MEK/ERK y/o PI3K/Akt. En el presente estudio, las células MDA-MB-231 se trataron con la DHEA en presencia de inhibidores farmacológicos de estos receptores y vías, así también se utilizó el siRNA contra el gen PIK3CA, que bloquea la vía PI3K. La proliferación celular se midió mediante la tinción con violeta cristal, la migración mediante los ensayos de cierre de herida y la migración usando placas transwell. Mientras que la expresión de las proteínas de la TEM por medio de Western blot. Así mismo se realizó un ensayo in vivo de xenotransplante en ratones desnudos (nu- /nu- ) utilizando el siRNA contra PIK3CA. Los resultados mostraron que ninguno de los inhibidores utilizados revirtió la actividad antiproliferativa de la DHEA. Sin embargo, la wortmanina y el LY294002, inhibidores de la vía PI3K/Akt, revirtieron la inhibición de la migración y los cambios en la expresión de las proteínas E- y N-cadherina, inducidos por la DHEA en células MDA-MB-231. El siRNA contra PIK3CA abolió los efectos de la DHEA sobre la proliferación, la migración, la expresión de proteínas TEM y el crecimiento de tumores en ratones desnudos. En conclusión, estos resultados sugieren que la vía PI3K/Akt participa en los efectos de la DHEA en la línea celular MDA-MB-231.Cancer is one of the leading causes of worldwide deaths, and breast cancer is the leading cause of cancer death in women, so this thesis contributes to providing a better and effective treatment against breast cancer. Dehydroepiandrosterone (DHEA) is an adrenal steroid hormone present in a higher concentration than any other hormone in human plasma. DHEA has been shown to inhibit the proliferation and migration of breast cancer cells and to modify the expression of proteins involved in the epithelial-mesenchymal transition (EMT). However, the mechanisms involved in these effects are not fully understood. The effects of DHEA on the triple-negative breast cancer cell line MDA-MB-231 could be produced by its binding to the receptor of tyrosine kinase (RTK) and through the MEK/ERK and/or PI3K/Akt pathways. In this study, the MDA-MB-231 cells were treated with DHEA in the presence of pharmacological inhibitors of these receptors and pathways, as well as a siRNA against the PIK3CA gene. Cell proliferation was measured by crystal violet staining, migration by wound healing and transwell assays, and protein expression by Western blot. An in vivo xenograft assay was performed in nude mice (nu- /nu- ) using siRNA against PIK3CA. The results showed that none of the inhibitors used reversed the antiproliferative activity of DHEA. However, wortmannin and LY294002, PI3K/Akt pathway inhibitors, reversed the migration inhibition and the changes in the E- and N-cadherin proteins expression, induced by DHEA in MDA-MB-231 cells. The siRNA against PIK3CA abolished DHEA´s effects on proliferation, migration, EMT protein expression, and tumor growth in nude mice. In conclusion, these results suggest that the PI3K/Akt pathway participates in the effects of DHEA in the MDA-MB-231 cell line
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
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