1,720,957 research outputs found
Differential expression of glutamate transporter genes after chronic oral treatment with aripiprazole in rats
No full textGlutamatergic neurotransmission is critically involved into the pathogenesis of schizophrenic psychosis, in particular regarding cognitive and negative symptoms. The reported molecular mechanisms include increased glutamate transporter expression and antipsychotic agents such as clozapine were found able to suppress the expression of these genes. So far, the effects of the partial dopaminergic and serotonergic agonist aripiprazole on glutamatergic neurotransmission were never investigated. In a rat animal model of long-term antipsychotic treatment, we analyzed the expression of glutamate transporter genes after treatment with aripiprazole. Groups of 6 male Sprague-Dawley rats were treated for 4 weeks or 4 months with daily oral doses of 10 or 40 mg aripiprazole per kg. Using semi-quantitative in situ-hybridization, we assessed the expression of pre- and post-synaptic glutamate transporter genes. Compared to control animals, differential expression levels were found in several cortical and hippocampal regions. The astroglial excitatory amino acid transporter genes EAAT1 and EAAT2 as well as the neuronal transporter EAAT3 were suppressed, while the presynaptic vesicular glutamate transporter vGluT1 was transiently induced in hippocampal subregions and EAAT4 was transiently suppressed in frontocortical areas. These transcriptional effects exerted by aripiprazole may counteract a glutamatergic deficit state and strengthen the neurotransmission of glutamate with positive consequences on cognitive and negative symptoms of schizophrenia. (C) 2009 Elsevier Ltd. All rights reserved
EFFECTS OF CHRONIC ORAL TREATMENT WITH ARIPIPRAZOLE ON EXPRESSION OF NMDA RECEPTOR SUBUNITS AND BINDING SITES IN RAT BRAIN
No full textEFFECTS OF CHRONIC ORAL TREATMENT WITH ARIPIPRAZOLE ON EXPRESSION OF NMDA RECEPTOR SUBUNITS AND BINDING SITES IN RAT BRAIN
No full textEffects of chronic oral treatment with aripiprazole on the expression of NMDA receptor subunits and binding sites in rat brain
No full textThe glutamatergic theory of schizophrenia proposes a dysfunction of ionotropic N-methyl-d-aspartate receptors (NMDA-R). Several therapeutic strategies address NMDA-R function and the effects of antipsychotic agents on NMDA-R expression have been described. Within the second-generation antipsychotics, the partial dopaminergic and serotonergic agonist aripiprazole (APZ) was able to counteract the behavioral effects of NMDA-R antagonists. This study aims to investigate the effects of APZ on NMDA-R subunit expression and binding. We treated Sprague-Dawley rats for 4 weeks or 4 months with APZ in daily oral doses of 10 and 40 mg per kilogram of body weight. Gene expression of the NMDA-R subunits NR1, NR2A, NR2B, NR2C, and NR2D, respectively, was assessed by semiquantitative radioactive in situ hybridization and in parallel receptor binding using (3)H-MK-801 receptor autoradiography. Increased expression levels of NR1 (4 weeks), NR2A (4 weeks), NR2C (4 weeks and 4 months), and NR2D (4 months) were observed in several hippocampal and cortical brain regions. The parallel reduced expression of NR2B mRNAs (4 months) resulted in a relative increase of the NR2A/NR2B ratio. Marked differences between specific brain regions, the doses of APZ, and the time points of assessment became obvious. On the receptor level, increased MK-801-binding was found after 4 weeks in the 40-mg group and after 4 months in the 10-mg group. The effects of APZ converge in enhanced NMDA receptor expression and a shift of subunit composition towards adult-type receptors. Our results confirm the regulatory connections between dopaminergic, serotonergic, and glutamatergic neurotransmissions with relevance for cognitive and negative symptoms of schizophrenia
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
Effekte chronischer antipsychotischer Behandlung mit Aripiprazol auf die Expression glutamaterger und GABAerger Markergene
Full text linkDispelling 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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