1,720,962 research outputs found
Ablation of Ca2+ channel beta 3 subunit leads to enhanced N-methyl-D-aspartate receptor-dependent long term potentiation and improved long term memory
No full textThe beta subunits of voltage-dependent Ca2+ channels (VDCCs) have marked effects on the properties of the pore-forming alpha(1) subunits of VDCCs, including surface expression of channel complexes and modification of voltage-dependent kinetics. Among the four different beta subunits, the beta 3 subunit (Ca-v beta 3) is abundantly expressed in the hippocampus. However, the role of Ca-v beta 3 in hippocampal physiology and function in vivo has never been examined. Here, we investigated Ca-v beta 3-deficient mice for hippocampus-dependent learning and memory and synaptic plasticity at hippocampal CA3-CA1 synapses. Interestingly, the mutant mice exhibited enhanced performance in several hippocampus-dependent learning and memory tasks. However, electrophysiological studies revealed no alteration in the Ca2+ current density, the frequency and amplitude of miniature excitatory postsynaptic currents, and the basal synaptic transmission in the mutant hippocampus. On the other hand, however, N-methyl-D-aspartate receptor (NMDAR)-mediated synaptic currents and NMDAR-dependent long term potentiation were significantly increased in the mutant. Protein blot analysis showed a slight increase in the level of NMDAR-2B in the mutant hippocampus. Our results suggest a possibility that, unrelated to VDCCs regulation, Ca-v beta 3 negatively regulates the NMDAR activity in the hippocampus and thus activity-dependent synaptic plasticity and cognitive behaviors in the mouse.This work was supported by the National Honor Scientist Program of Korea, grants from Korea Institute of Science and Technology, the National Creative Research Initiatives of the Ministry of Science and Technology of Korea, and Virginia Commonwealth University Medical Center Grant NEI EY12716. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact
Role of the alpha 1G T-type calcium channel in spontaneous absence seizures in mutant mice
No full textAlterations in thalamic T-type Ca2+ channels are thought to contribute to the pathogenesis of absence seizures. Here, we found that mice with a null mutation for the pore-forming alpha1A subunits of P/Q-type channels (alpha1A(-/-) mice) were prone to absence seizures characterized by typical spike-and-wave discharges (SWDs) and behavioral arrests. Isolated thalamocortical relay (TC) neurons from these mice showed increased T-type Ca2+ currents in vitro. To examine the role of increased T-currents in alpha1A(-/-) TC neurons, we cross-bred alpha1A(-/-) mice with mice harboring a null mutation for the gene encoding alpha1G, a major isotype of T-type Ca2+ channels in TC neurons. alpha1A(-/-)/alpha1G(-/-) mice showed a complete loss of T-type Ca2+ currents in TC neurons and displayed no SWDs. Interestingly, alpha1A(-/-)/alpha1G(+/-) mice had 75% of the T-type Ca2+ currents in TC neurons observed in alpha1A (+/+)/alpha1G (+/+) mice and showed SWD activity that was quantitatively similar to that in alpha1A (-/-)/alpha1G (+/+) mice. Similar results were obtained using double-mutant mice harboring the alpha1G mutation plus another mutation also used as a model for absence seizures, i.e., lethargic (beta4(1h/1h)), tottering (alpha1A(tg/tg)), or stargazer (gamma2(stg/stg)). The present results reveal that alpha1G T-type Ca2+ channels play a critical role in the genesis of spontaneous absence seizures resulting from hypofunctioning P/Q-type channels, but that the augmentation of thalamic T-type Ca2+ currents is not an essential step in the genesis of absence seizures
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
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
- …
