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Per un ritratto del congiurato nella Napoli Aragonese: scritture di parte
No full textSi studia il modo in cui il Principe di Taranto, gran congiurato di Ferrante, viene descritto dalla penna 'di parte' di Paracleto Malvezzi da Corneto
Protein kinase A-dependent increase in frequency of miniature GABAergic currents in rat CA3 hippocampal neurons
No full textThe whole-cell configuration of the patch clamp technique was used to study the effect of an intracellular increase in cAMP on the frequency of GABA-mediated miniature post synaptic currents (MPSCs) in neonatal rats from (P6 to P12) CA3 hippocampal neurons in slices. In the presence of tetrodotoxin (1 μM), and kynurenic acid (1 mM) to block ionotropic glutamatergic currents, forskolin, an activator of adenylate cyclase, markedly increased the frequency of MPSCs without affecting their amplitude or kinetics. The inactive forskolin analog, 1,9-dideoxyforskolin (30 μM), had no effect on the frequency of MPSCs. The effect of forskolin was prevented by the specific protein kinase A (PKA) antagonist Rp-cAMP (30 μM). It is concluded that stimulation of PKA potentiates spontaneous GABA release in immature hippocampal neurons. © 1995
GABA excites CA3 pyramidal cells through bicuculline sensitive and insensitive chloride-dependent receptors
No full textIntracellular and patch clamp recording techniques were used to investigate the role of GABA in immature CA3 hippocampal neurons. During the first postnatal week spontaneous GABA release was detected as spontaneous ongoing synaptic potentials (SPSPs) or giant depolarizing potentials (GDPs). GDPs were generated at regular intervals and regulated by ionotropic glutamate receptors (GluRs), whereas SPSPs occurred randomly and were unaffected by ionotropic GluRs. Both GDPs and SPSPs were positively modulated by metabotropic GluRs through cyclic AMP-dependent protein kinase. Moreover GABA controlled its own release through GABAA and GABAB receptors, probably localized on GABAergic nerve terminals. At this developmental stage, GABA depolarized CA3 pyramidal cells through two distinct classes of chloride-permeable receptors: bicuculline sensitive and insensitive, respectively. The bicuculline-insensitive responses were blocked by picrotoxin in a noncompetitive way. Whole-cell GABA currents, recorded in the presence of bicuculline, had a slower desensitization rate and faster recovery from desensitization. In excised outside-out patches, in the presence of bicuculline, GABA activated single-channel currents with conductances of 14, 22, and 31 pS. These values were similar to those obtained when GABA was applied in the absence of bicuculline. Interestingly, GABA responses obtained in the absence of bicuculline, were sensitive to the blocking effect of zinc, whereas bicuculline-resistant responses were almost unaffected by this divalent cation. Expression of different subunits in native receptors (particularly of the alpha and rho type) may account for the functional differences observed in the present experiments. Activation of bicuculline-insensitive receptors would strengthen and prolong the depolarizing action of GABA, thus favoring the entry of calcium through voltage-dependent calcium channels. This calcium signal may be essential in promoting stabilization of synaptic contacts during a critical period of postnatal development
cAMP-dependent modulation of giant depolarizing potentials by metabotropic glutamate receptors in the rat hippocampus
No full textSingle-channel currents of NMDA type activated by L- and D-Homocysteic acid in cerebellar granule cells in culture
No full textThe whole-cell and the outside-out configurations of the patch-clamp technique were used to study macroscopic and single-channel currents evoked by the enantiomers of homocysteic acid, the sulphur containing analogue of glutamate, in cerebellar granule cells in culture. L-Homocysteic acid (L-HC, 15-mu-M) and D-homocysteic acid (D-HC, 50-mu-M) induced whole-cell currents of comparable amplitude, that were abolished by the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonovalerate (AP-5) (20-mu-M). AMPA (100-mu-M) induced whole-cell currents which were not modified by AP-5 (20-mu-M) but were blocked by CNQX. In the outside-out configuration, both L-HC and D-HC (15-mu-M) elicited single-channel currents. of the same conductance, mean open time and reversal potential as the NMDA-induced single-channel events. In the presence of Mg2+ (2 mM), D- and L-HC-induced single-channel currents were voltage-dependent. These data suggest that in cerebellar granule cells in culture, both L-HC and D-HC activate the same NMDA receptor channel complex
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
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