1,720,969 research outputs found
Steroid hormones and receptors of the GABAA supramolecular complex. 2. Progesterone and estrogen inhibitory effects on the chloride ion channel receptor in different forebrain areas of the female rat
No full textThe inhibitory effect of female sex steroid hormones on the binding of [S-35]t-butylbicyclophosphorothionate [S-35]TBPS to the chloride ion channel receptor in different forebrain areas of the female rat proved to be of a differential nature. The in vivo administration of estradiol and estradiol + progesterone were responsible for substantially lower chloride ion channel receptor levels in brain areas that contain elevated steroid receptors, such as the medial preoptic area, the cortico-medial amygdala nucleus, the vertical limb diagonal band-medial septal nucleus and the cortex lamina V. The administration of progesterone alone reduced receptor levels in the oriens-pyramidalis CA1 layer of the hippocampus, caudate putamen, cortex lamina VI (brain areas that contain little if any steroid receptors) and in the lateral and basolateral amygdala nucleus (brain sites that contain noninducible progesterone receptors). On the basis of the progesterone-inhibitory activity on the chloride ion channel receptors, it was important to investigate whether progesterone per se or whether the potent progesterone metabolites 3alpha-hydroxy-5alpha-dihydroprogesterone (3alpha,5alpha-THP) and 3beta-hydroxy-5beta-dihydroprogesterone (3beta,5beta-THP) were involved in the binding level changes, and to establish the specific brain sites where these steroid effects occur. In fact, in vitro addition of the 5alpha-reduced progesterone metabolite produced even greater depressive effects on [S-35]TBPS binding not only in the same brain areas as the in vivo progesterone replacement therapy but also in some sites that provided significant receptor level changes following the sequential administration of estradiol + progesterone. However, when the 5beta-reduced metabolite was tested on the binding of [S-35]TBPS to the chloride ion channel receptor, only the basolateral amygdala nucleus, the cortex lamina VI and the dorsolateral septal nucleus exhibited changes. Because the steroid-mediated chloride ion flux is regulated in a GABA-dependent manner, we next checked for the type of GABA effects on the chloride ion channel receptor levels and found that GABA not only intensified the 3alpha,5alpha-THP inhibitory effects but, together with this progesterone metabolite, was also involved in binding changes in the vertical limb diagonal band-medial septal nucleus. It is interesting to note that the GABA effects on 5beta-metabolite-induced receptor changes were not of the enhancing type, but tended, rather, to be inhibitory. Moreover, the addition of the GABA antagonist bicuculline to the in vitro hormone treatment in the presence of GABA, caused a notable and specific inhibitory effect only to 3alpha,5alpha-THP-induced chloride ionophore receptor levels, indicating that this metabolite is probably the main modulator involved in the progesterone-dependent GABAergic functions via a specific interaction with the neurosteroid site of the GABA molecule in the various brain areas
Differential modulation of [3H]flunitrazepam binding in female rat brain by sex steroid hormones
No full textQuantitative autoradiographic analysis revealed changes in [3H]flunitrazepam (a benzodiazepine agonist) binding in the anterior hypothalamus nucleus, the medial preoptic area and the cortico-medial amygdala nucleus following in vivo estradiol. The administration of 4 mg of progesterone, but not 1 mg, increased the binding of [3H]flunitrazepam in the basolateral amygdaloid nucleus and in the oriens-pyramidalis CA1 layer of the hippocampus. Exposure of brain sections in vitro to the potent, naturally occurring progesterone metabolite, 3 alpha-hydroxy-5 alpha-dihydroprogesterone, induced GABA-dependent changes in flunitrazepam binding, similar to the changes induced by progesterone, thus suggesting that different steroid mechanisms are implicated in the control of flunitrazepam binding
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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