1,721,027 research outputs found
Thyroid hormone-regulated molecular mechanisms driving mouse blastocyst implantation
No full textEmbryo implantation is one of the earliest and critical events of the mammalian reproduction.1 A clinical association between implantation failure and thyroid dysfunction has been extensively reported, although the molecular mechanism governing this correlation has not been elucidated yet. TH machinery is expressed in the feto-maternal unit at the time of implantation, suggesting a locaI action of TH. We have investigated the role of TH in mouse hatching and outgrowth, since dysregulation of these events induces implantation failure, leading to infertility.2 Mouse blastocysts were cultured on a feeder-layer of primary endometrial cells or on plastic, with or without TH supplementation, and hatching and outgrowth evaluated. TH stimulation was also studied on endometrial cell cultures without blastocysts. By qRT-PCR, the expression of two proteases involved in blastocyst hatching in mice (Ispl and Isp2 3,4) and MMPS was studied. TH supplementation significantly increased the number of hatching blastocysts cultured on the endometrial cells, while had limited effect on blastocysts cultured on plastic. Ispl and Isp2 were significantly up-regulated in both blastocysts and endometrial cells, independently analyzed after an overnight coculture with TH; a less pronounced effect was observed in both blastocysts and endometrial cells cultured alone. TH also induced a significant upregulation of several MMPs in endometrial cells, independently from the presence of the blastocysts, although the coculture induced a much higher increase. TH also significantly increased the expansion of trophectodermal cells in both culture conditions, however expansion was more pronounced in the presence of the endometrial feeder layer. TH plays a key role in the bidirectional crosstalk between the competent blastocyst and the receptive endometrium at the time of implantation. TH supplementation may improve implantation success.
1. Zhang S et al. Mol Aspects Med 2013,34;939
2. Petersen CG et al. Reprod Biomed Online 2005, 10;24
3. O'Sullivan CM et al. Mol Reprod Devel 2002, 62; 328
4. Sharma et al. BMC Dev Biol 2006, 6;6
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
p75 neurotrophin receptor is involved in proliferation of undifferentiated mouse embryonic stem cells
No full textNeurotrophins and their receptors are known to play a role in the proliferation and survival of many different cell types of neuronal and non-neuronal lineages. In addition, there is much evidence in the literature showing that the p75 neurotrophin receptor (p75NTR), alone or in association with members of the family of Trk receptors, is expressed in a wide variety of stem cells, although its role in such cells has not been completely elucidated. In the present work we have investigated the expression of p75NTR and Trks in totipotent and pluripotent cells, the mouse pre-implantation embryo and embryonic stem and germ cells (ES and EG cells). p75NTR and TrkA can be first detected in the blastocyst from which ES cell lines are derived. Mouse ES cells retain p75NTR/TrkA expression. Nerve growth factor is the only neurotrophin able to stimulate ES cell growth in culture, without affecting the expression of stem cell markers, alkaline phosphatase, Oct4 and Nanog. Such proliferation effect was blocked by antagonizing either p75NTR or TrkA. Interestingly, immunoreactivity to anti-p75NTR antibodies is lost upon ES cell differentiation. The expression pattern of neurotrophin receptors in murine ES cells differs from human ES cells, that only express TrkB and C, and do not respond to NGF. In this paper we also show that, while primordial germ cells (PGC) do not express p75NTR, when they are made to revert to an ES-like phenotype, becoming EG cells, expression of p75NTR is turned on. © 2009 Elsevier Inc. All rights reserved
Phosphodiesterase specific inhibitors control cell growth of a human neuroepithelioma cell line
No full textThe effects of cyclic nucleotide phosphodiesterase (PDE) inhibitors on cell
proliferation of SK-N-MC human neuroepithelioma cell line was studied. Clonal
density experiments in the presence of 100 microM rolipram and zaprinast showed
respectively 27% and 91% inhibition. The effects of PDE inhibitors were then
investigated on crude cell extracts; the calculated IC50 were 32 microM for
zaprinast and 16 nM for DC-TA-46; the latter inhibitor was used instead of
rolipram for its higher efficacy. Dose-response experiments in clonal density
conditions showed IC50 of 5 microM and 1.8 microM in the presence respectively of
zaprinast and rolipram. These data show that both inhibitors are effective in
reducing cell growth, although the response was quantitatively different
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
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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