1,720,972 research outputs found
Eptastigmine restores the aged rat's normal cortical spectral power pattern
No full textWe studied the ability of eptastigmine, a second-generation acetylcholinesterase inhibitor (AChEI), to reverse the age-related increase of electroencephalogram (EEG) mean cortical spectral power in slow-wave delta activity and decrease in fast-wave alpha and beta activity. The relative basal spectral power profile evaluated for 50 min of the old (27-30 months) in comparison to young (4-6 months) awake rats was consistently different, showing a significant increase in delta (0.2-4.0 Hz) frequency and a significant decrease of alpha (8.2-13.0 Hz) and beta (13.2-25.0) bands. When 0.5, 1, 2, 4 mg kg(-1) of eptastigmine were administered orally as single increasing doses for old and young rats 2 h prior to the EEG recordings, lasting 2 h, the relative mean spectral power difference (Delta%) showed a linear log dose-related decrease in 6 activity and a progressive increase in a and beta activity in old rats. Compared to vehicle, in young rats, the eptastigmine dose of 0.5 mg kg(-1) produced a significant decrease in 6 activity and an increase in beta activity. The spontaneous motor activity, evaluated through cumulative horizontal and vertical counts for 30 min in old rats was significantly decreased when compared to young rats. Single oral treatment with eptastigmine (0.5 mg kg(-1) for young and 2 mg kg(-1) for old rats) given 2 h before the test did not significantly change motor activity in comparison to vehicle group of the same age. These results suggest a possible strategy to alleviate the severe slowing of neocortical EEG accompanying the cognitive decline
Eptastigmine improves eight-arm radial maze performance in aged rats
No full textEptastigmine, a potent and long-lasting cholinesterase inhibitor on age-related memory deficits, was studied. Four groups of 3-, 18-, 23- and 27-month-old Wistar rats were first submitted to spontaneous motor activity evaluation and then trained in an eight-arm radial maze until they reached the criterion. The effect of introducing a 2-h delay between the fourth and fifth choices was then evaluated under the influence of acute oral dose of eptastigmine (0.5mgkg−1 ) 120 min before the test. Eptastigmine reversed the impairment observed in vehicle-treated rats at all the tested ages. Two naive groups of 3- and 18-month-old rats were treated twice a day for 30 days with eptastigmine ( 0.25 mgkg−1p.o.) or vehicle and trained daily in the maze. Subchronic administration did not affect the performance in young rats, while in 18-month-old rats, the mean number of days needed to reach the criterion decreased and the percentage of animals reaching the criterion increased when compared to the vehicle group. The 18-month-old rats (ex-eptastigmine and ex-vehicle) were then allowed to age in their home cage without any further treatment for an additional 5 and 9 months, until they reached 23 and 27 months. The ex-eptastigmine rats tested at 23 months, without any treatment, showed better performance than that observed in ex-vehicle rats. When the same rats were tested again at 27 months of age, no difference was seen in comparison with ex-vehicle rats. Eptastigmine might, therefore, be helpful for correcting age-related memory impairment attributed to cholinergic hypofunction
Excitatory and inhibitory effects of second-generation cholinesterase inhibitors on rat gastrointestinal transit
No full textWe investigated the influence of increasing oral doses of second generation acetylcholinesterase inhibitors (AChEI) such as tacrine (0.25, 0.5, 1, 2, 3, 4, 10, and 20 mg kg(-1)), eptastigmine (0.5, 4, 8, 12, 20 and 40 mg kg(-1)) and E2020 (0.18, 0.25, 0.5, 1, 2, 3, 4 and 10 mg kg(-1)) on the distance travelled by a charcoal meal administered 30 min after each compound, in comparison with physostigmine (0.5, 1, 2, 4, 8 and 12 mg kg(-1)). An inverted U regression was observed with a significant parabola between the centimetres travelled and the log of the doses for all AChEI. The maximal stimulating doses (mg kg(-1)) were 2 for physostigmine, 4 for eptastigmine, 3 for tacrine and E2020, while the inhibitory doses were 12 for physostigmine, 40 for eptastigmine, 20 for tacrine and 10 for E2020. The stimulating and inhibiting effects on gastrointestinal propulsion were significantly reversed by 0.25 mg kg(-1) of scopolamine hydrobromide. A dose of scopolamine hydrobromide (0.06 mg kg(-1)) or methylbromide (0.25 mg kg(-1)), pirenzepine dihydrochloride (0.25 mg kg(-1)) and mecamylamine hydrochloride (0.5 mg kg(-1)), which per se did not affect gastrointestinal propulsion, antagonized both the stimulating and inhibitory effect of eptastigmine. Thus, the biphasic effect is peripherally mediated through both muscarinic (at least M-1) and nicotinic receptors
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
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