1,720,996 research outputs found
Investigating the role of ABCA1 in the externalisation of Annexin 1 in the anterior pituitary
No full textAnnexin 1 (Anx-1), a 37kDa protein, is a member of the super-family of Ca 2+ and phospholipid-binding annexin proteins and acts as a mediator of glucocorticoid (GC) action in the host defense and neuroendocrine systems. In the anterior pituitary Anx-1 is expressed mainly by folliculostellate (FS) cells and mediates the early delayed feedback inhibition exerted by GCs on the release of ACTH and other pituitary hormones. It has been previously demonstrated that TtT/GF cells (mouse pituitary-derived FS cells) express and externalize Anx-1 in response to GC 1. However, Anx-1 lacks a cleavable signal sequence and the externalization was not affected by inhibitors of the secretory pathway 2. We have previously shown that glyburide, an inhibitor of ATP-binding cassette (ABC) transporters inhibited the externalization of Anx-1 from TtT/GF cells 3. Here we investigated the mechanism of Anx-1 externalization from TtT/GF cells by ABCA1. Unlike glyburide, the use of selective ABCA1 inhibitors such as geranyl-geranyl pyrophosphate (GGPP) and sulfobromopthalein (SBP) did not markedly decrease Anx-1 externalization. Furthermore, it was found that silencing ABCA1 expression in TtT/GF cells by siRNA did not affect Anx-1 externalization. This was further confirmed by investigating Anx-1 externalization from pituitaries from ABCA1 knock out mice, where the knockout mice were found to externalize Anx-1 normally. However, since compensation by other ABC family members may occur in vivo, Anx-1 externalization was studied in zenopus oocytes injected with ABCA1 mRNA. The ABCA1 expressing oocytes were found to efficiently externalize endogenous Anx-1 providing good evidence for a role of ABCA1 in Anx-1 expor
Microglia in the neurohypophysis associate with and endocytose terminal portions of neurosecretory neurons
No full textThe rat neurohypophysis contains a population of microglial cells, the majority of which occupy a pericapillary position in the resting gland. The microglia are immunocytochemically identifiable by the presence of macrophage-associated antigens and resemble microglia of the CNS. Morphometry at light and electron microscopic levels reveals that such cells constitute approximately 19% of the intrinsic cell population, excluding the endothelial cells. Two other populations of neurohypophysial glial cells, parenchymatous pituicytes and fibrous pituicytes, do not express macrophage-associated antigens. The microglia have long processes which surround and, in some cases, engulf apparently viable portions of the magnocellular neurosecretory nerve terminals. A sequence of stages of selective endocytosis and degradation of the engulfed nerve terminals can be visualized within pericapillary microglia. Some phagosomes and secondary lysosomes contain morphologically intact neurosecretory granules; others contain partially destroyed neurosecretory granules or amorphous material all of which are identifiable as originating from the magnocellular neurosecretory terminals by their immunoreactivity for oxytocinor vasopressin-neurophysin. This finding indicates a novel role for the microglial cells in remodelling terminal arborizations of neurosecretory neurons and in processing or degrading hormones and peptides they contain. Because of their close and selective associations with other cellular elements of the neurohypophysis, any substances produced by microglia also have the potential to influence hormone secretion, pituicyte proliferation and neurohypophysial vasculature.</p
Does Annexin-1 have a biological function in the adrenal gland?
No full textAnnexin-1 (Anx-1), a 37kDa protein, is a member of the super-family of Ca2+- and phospholipid-binding annexin proteins and acts as a mediator of glucocorticoid (GC) action in the host defence and neuroendocrine systems. In the anterior pituitary Anx-1 is expressed mainly by folliculostellate (FS) cells and mediates the early delayed feedback inhibition exerted by GCs on the release of ACTH and other pituitary hormones.The role of Anx-1 in the adrenal gland was investigated. It has already been shown that Anx-1 mRNA and protein is abundantly expressed in the adrenal gland. The localisation of Anx-1 was further investigated by in situ hybridisation, immunhistochemistry, electron microscopy and real-time PCR, using a cDNA tissue panel derived from perfused mouse adrenal tissues to eliminate contamination by Anx-1 expressing macrophages. The localisation of Anx-1 expression in the adrenal gland was also investigated by the localisation of x-gal reactivity in Anx-1 knock-out mice, which was shown to be in the peripheral part off the adrenal cortex. Functional studies were carried out using isolated primary adrenal cells in static cell culture incubations from both Anx-1 knock-out and wild-type mice. The cells from Anx-1 knock-out mice were found to be more responsive to ACTH stimulation compared to wild type controls. PCR studies indicate that there is no up-regulation of ACTH receptors in the adrenal gland of Anx-1 knock-out mice, therefore, these results are consistent with our hypothesis that Anx-1 may mediate a glucocorticoid ultra-short negative feedback loop in the adrenal gland. The effect of the potent Anx-1 2-26 peptide on steroid production is currently being investigated using perifused primary adrenal cells. In addition the responses of adrenal cells to ACTH in the presence and absence of the glucocorticoid receptor antagonist RU486 are being compared
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
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