1,720,989 research outputs found
Neuron-glia crosstalk revealed in reverberating networks by simultaneous extracellular recording of spikes and astrocytes' glutamate transporter and K+ currents
Full text linkAstrocytes reuptake synaptically released glutamate with electrogenic transporters (GluT), and buffer the spike-dependent extracellular K(+) ([K(+)]o) excess with background K(+) channels. We studied neuronal spikes and the slower astrocytic signals on reverberating neocortical cultures and organotypic slices from mouse brains. Spike trains and glial responses were simultaneously captured from individual sites of multi-electrode arrays (MEA), by splitting the recorded traces into appropriate filters, and reconstructing the original signal by deconvolution. GluT currents were identified by using DL-threo-beta-benzyloxyaspartate (TBOA). K(+) currents were blocked by 30 μM Ba(2+), suggesting a major contribution of inwardly rectifying K(+) currents (Kir) Both types of current were tightly correlated with the spike rate, and their astrocytic origin was tested in primary cultures by blocking glial proliferation with cytosine β-d-arabinofuranoside (AraC). The spike-related, time-locked inward and outward K(+) currents in different regions of the astrocyte syncytium were consistent with the assumptions of the spatial K(+) buffering model. In organotypic slices from ventral tegmental area (VTA) and prefrontal cortex (PFC), the GluT current amplitudes exceeded those observed in primary cultures by several orders of magnitude, which allowed to directly measure transporter currents with a single electrode. Simultaneously measuring cell signals displaying widely different amplitudes and kinetics will help clarify the neuron-glia interplay, and make it possible to follow the cross-talk between different cell types in excitable as well as non-excitable tissue
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
Effect of carbamazepine and oxcarbazepine on wild-type and mutant neuronal nicotinic acetylcholine receptors linked to nocturnal frontal lobe epilepsy
No full textCarbamazepine (5H-dibenz[b,f]azepine-5-carboxamide) and oxcarbazepine (10,11-dihydro-10-oxo-5H-dibenz[b,f]azepine-5-carboxamide) are widely used for the treatment of partial epilepsy. Recent work indicates that these drugs, in addition to targeting voltage-gated Na(+) channels, can modulate ligand-gated channels. These compounds appear to be particularly effective for treatment of nocturnal frontal lobe epilepsy, which can be caused by mutant neuronal nicotinic receptors. We compared the effects of carbamazepine and oxcarbazepine on heteromeric nicotinic receptors to better understand the underlying mechanism of the effect of these drugs in epileptic patients. Receptors were expressed in cell lines and studied by patch-clamp methods at -60 mV. For alpha2beta4 receptors activated with 100 microM nicotine, IC(50) for carbamazepine was 49 microM. Receptors in which alpha2 was substituted with alpha2-I279 N, linked to autosomal dominant nocturnal frontal lobe epilepsy, had an IC(50) of 21 microM. For oxcarbazepine, the IC(50) was larger than 500 microM for wild-type receptors and approximately 100 microM for mutant receptors. A similar inhibition was observed in the presence of 10 microM nicotine, indicating a non-competitive mechanism. The monohydroxy derivative (MHD) of oxcarbazepine, clinically the most relevant compound, was tested on both alpha2beta4 and alpha4beta2 receptors, to obtain a broader view of its possible physiological effects. At the typical concentration present in blood (100 microM), MHD produced an approximate 40% channel block on alpha4beta2, but no significant effect on alpha2beta4 receptors. Oxcarbazepine and MHD retarded the channel deactivation, suggesting that these compounds produce open channel block. These results may explain the particular efficacy of these drugs in nocturnal frontal lobe epilepsy
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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