1,721,098 research outputs found
Sexual differentiation of mammalian frontal cortex
No full textThe pattern of distribution of the progesterone binding sites was examined in selected nuclei of the brain of male and female rat. In female rats the frontal cortex resulted to be the region with the highest concentration of 3H R5020 binding sites. However, in male rats the same region showed very little progestin binding activity. When female rats were androgenized via neonatal exposure to testosterone, the progestin binding activity of the frontal cortex became similar to that we observed in male rats. The present investigation indicates that sexual differentiation of the rat brain may include also brain regions not clearly involved in sex related functions like the frontal cortex
Progesterone in rat brain: modulation of beta-adrenergic receptor activity
No full textCytosolic proteins binding specifically the progesterone analogue 3H R5020 can be detected in various areas of the central nervous system (CNS) of rat. Our study demonstrates that the concentration of progesterone receptors in the brain of adult, ovariectomized, female rats is maximal in frontal cortex and midbrain and lowest in the cerebellum. Short term administration of the hormone does not alter the beta-adrenergic receptor system, while a prolonged administration of progesterone results in an up-regulation of 3H-DHA binding in the frontal cortex. Such increase in binding activity is due to an increased number of beta-adrenergic receptors. Furthermore, high doses of progesterone can also increase the number of beta-adrenergic binding sites in an "in vitro" system where brain slices are incubated for few hours in a physiological medium
Estrogen modulation of the gamma-aminobutyric acid receptor complex in the central nervous system of rat
No full textAdministration of estradiol benzoate to ovariectomized rats results in an increased binding of [3H]muscimol, [3H]diazepam and 35S-t-butylbicyclophosphorothionate in various areas of the central nervous system of rats. The effect is dose-dependent and its onset can be observed as early as 12 hr after s.c. administration of the hormone. The various binding activities are differentially affected by the hormonal treatment: the maximal effect observed for [3H]diazepam binding is in the cerebellum (+42%), for [3H]muscimol binding in the frontal cortex (+84%) and for 35S-t-butylbicyclophosphorothionate binding in the striatum (+46%) indicating that the activities of the sites are not under the same cellular regulatory control. The estrogen-induced increase in [3H]diazepam binding sites does not result in an increased protection against chemoconvulsants such as pentylenetetrazole
SEXUAL DIMORPHISM IN THE RESPONSE OF THE GABAERGIC SYSTEM TO ESTROGEN ADMINISTRATION
No full textAdministration of estradiol benzoate to gonadectomized female rats results in up-regulation of CNS gamma-aminobutyric acid (GABA) receptors. The increase of [3H]muscimol binding activity is observed in six of the seven brain areas examined. The same treatment, performed in castrated male or androgenized female rats, induced an increase of [3H]muscimol binding only in the striatum. Evidence is provided suggesting that the dimorphic sensitivity of GABA receptor is not correlated with the difference in spontaneous motor activity reported between male and female rats
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
HIPPOCAMPUS - A TARGET FOR ESTROGEN ACTION IN MAMMALIAN BRAIN
No full textAn analysis of the distribution of estrogen receptor (ER) via immunoenzymatic assay in the brain of ovariectomized rats reveals the presence of large amounts of ER-like immunoreactive material in the cytosol of the hippocampus: a brain area described to contain little estrogen-binding activity. The protein detected in the hippocampus by the specific antibody is indistinguishable from the rat ER in its response to hormonal treatments and in its electrophoretic mobility. The presence of elevated amounts of ER in such an important part of the limbic system creates new possibilities for interpreting the role played by this sex hormone in the central nervous system of ra
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
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