1,720,963 research outputs found
The calcineurin inhibitor, cyclosporin A cyclophilin A complex, reduces desensitization of GABAA-mediated responses in acutely dissociated rat hippocampal neurons
No full textModulation of GABAergic synaptic currents and current responses by alf-thujone and dihydroumbellulone
No full textEffect of extracellular pH on recombinant alpha1 beta 2 gamma 2 and alpha1 beta 2 GABAA receptors
No full textDeclusterization of GABAA receptors affects the kinetic properties of GABAergic currents in cultured hippocampal neurons
No full textNew insights on the role of gephyrin in regulating both phasic and tonic GABAergic inhibition in rat hippocampal neurons in culture
No full textZinc modulation of bicuculline-sensitive and -insensitive GABA receptors in the developing rat hippocampus
No full textIntracellular recordings were used to study the effects of zinc on the bicuculline-sensitive and -insensitive responses evoked by GABA in CA3 rat hippocampal neurons in slices obtained from postnatal day (P) 0 to P8. In the absence of bicuculline, zinc inhibited GABA-induced responses in a concentration-dependent manner. This effect was developmentally regulated, being maximal (50%) between P0 and P5 and then declining to 30% after P5. In the presence of bicuculline, GABA-resistant responses were potentiated in 49% of cases, depressed in 38% and not affected in 13%. The period of maximum potentiation between P0 and P2 coincided with that of maximum expression of the bicuculline-resistant receptors. The effects of zinc were also studied using the whole-cell and outside-out configuration of the patch-clamp technique on bicuculline-sensitive and -insensitive GABA-induced currents elicited in isolated cells acutely dissociated from the same slices as those used for intracellular recordings. At a holding potential of -50 mV in symmetrical chloride solutions, GABA (50 and 100 mu M) activated whole-cell inward currents which were reversibly blocked by zinc, The EC(50) values for the blocking effect of zinc on currents evoked by 50 and 100 mu M GABA were 6.6 nM and 5.8 mu M respectively. In the presence of bicuculline (100 mu M), zinc potentiated the residual responses to GABA; the response curve was bell-shaped with a peak at 1 mu M. When the response to GABA was completely abolished by bicuculline, zinc (1 mu M) was often able to restore it. In the presence of bicuculline, however, zinc was not able to restore the response to isoguvacine. In two excised outside-out patches, zinc (1 mu M) increased the activity of opening of bicuculline-resistant GABA-evoked single channel currents (Np) from 1 to 1.87 and from 0.25 to 0.42 respectively, without changing single-channel conductance. These data suggest that down- or up-regulation of bicuculline-sensitive or -insensitive GABA receptors may be functionally important in regulating synaptic activity during development
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
New insights on the role of gephyrin in regulating both phasic and tonic GABAergic inhibition in rat hippocampal neurons in culture.
Full text linkGephyrin is a tubulin-binding protein that acts as a scaffold for clustering glycine and GABAA receptors at postsynaptic sites. In this study, the role of gephyrin on GABAA receptor function was assessed at the post-translational level, using gephyrin-specific single chain antibody fragments (scFv-gephyrin). When expressed in cultured rat hippocampal neurons as a fusion protein containing a nuclear localization signal, scFv-gephyrin were able to remove endogenous gephyrin from GABAA receptor clusters. Immunocytochemical experiments revealed a significant reduction in the number of synaptic γ2-subunit containing GABAA receptors and a significant decrease in the density of the GABAergic presynaptic marker vesicular GABA transporter (VGAT). These effects were associated with a slow down of the onset kinetics, a reduction in the amplitude and in the frequency of miniature inhibitory postsynaptic currents (mIPSCs). The quantitative analysis of current responses to ultrafast application of GABA suggested that changes in onset kinetics resulted from modifications in the microscopic gating of GABAA receptors and in particular from a reduced entry into the desensitized state. In addition, hampering gephyrin function with scFv-gephyrin induced a significant reduction in GABAA receptor-mediated tonic conductance. This effect was probably dependent on the decrease in GABAergic innervation and in GABA release from presynaptic nerve terminals. These results indicate that gephyrin is essential not only for maintaining synaptic GABAA receptor clusters in the right position but also for regulating both phasic and tonic inhibition
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
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