1,721,006 research outputs found
The role of opioid mechanisms in the anorectic effects of stimulants: U50,488H enhances amphetamine inhibition of free feeding in rats.
No full textThe influences of the kappa-opiate agonist U50,488H (U50; 4 mg/kg IP), the neuroleptic haloperidol (HAL; 0.3 mg/kg IP), and MK-801 (0.2 mg/kg IP), a noncompetitive antagonist for NMDA receptors, were compared on the effects of nine days of d-amphetamine (AMPH) treatment (3 mg/kg IP) on food and water intake and urine output. AMPH prevented feeding stimulation produced by U50 during the first 2 h, whereas U50 inhibited the hyperphagic phase that rats showed between 2 and 5 h after AMPH administration. Tolerance did not develop to the first 2-h suppression of feeding; in contrast, the late hyperphagic phase slowly recovered across the nine days of treatment. Combined administration of the two drugs barely affected water intake but considerably increased urine output. Unlike U50, HAL left the late hyperphagic response to AMPH unchanged and delayed the development of hyperdipsia. In our study MK-801 had one effect only: It significantly reduced amphetamine diuresis. These results suggest that by inhibiting the late hyperphagic response U50 enhances the anorectic effects of AMPH, but that dopamine probably has no direct role in this interaction
(-)-Norpseudoephedrine, but not (+/-)-amphetamine, prevents the increase in fluid intake associated with ethanol presentation in rats.
No full textThe effects of daily intraperitoneal administration of (+/-)-amphetamine (AMPH: 4 mg/kg) and (-)-norpseudoephedrine (NPE: 15 or 30 mg/kg) on drinking were evaluated in rats allowed to drink water or a 5\% ethanol solution during the 5 h following drug administration. AMPH, but not NPE, significantly increased water intake. Substitution of ethanol for water produced a significant increase in fluid intake in the control group, whereas drinking levels remained unchanged in both AMPH and NPE treated rats. Discontinuation of drug treatment during the regimen of ethanol presentation produced a prompt increase in fluid intake in the NPE, but not AMPH, treated groups. Finally, substitution of water for ethanol led to a significant reduction of fluid intake in all the groups. These results suggest that a light (i.e. NPE), but not a strong (i.e. AMPH) psychomotor stimulant, is able to weaken rewarding properties of diluted ethanol
The alpha 1-blocker dapiprazole inhibits diuresis but not drinking and feeding induced by U-50,488H.
No full textTo further explore the interaction between opiates and catecholamines in the control of water balance, we studied the effects of the alpha 1-adrenoceptor antagonist dapiprazole on the modifications in drinking and diuresis produced by U-50,488H (a selective kappa-opiate agonist), morphine, naloxone, and amphetamine in rats. Because animals were maintained in a free-feeding paradigm and water intake is also controlled by feeding (prandial drinking), food intake was also measured. At doses administered (3-6 mg/kg, IP), dapiprazole had no effect on basal food and water intake or on diuresis. Nor did it modify changes in feeding and drinking produced by U-50,488H, morphine, naloxone, and amphetamine. It did, however, antagonize the diuretic effect of both U-50,488H and amphetamine. In addition, suppression of diuresis was obtained by combining doses of dapiprazole and morphine or naloxone that were devoid of antidiuretic effects when administered independently. A further experiment showed that diuresis produced by water load was also prevented by dapiprazole. alpha 1-Adrenoceptors thus appear to play a role in the regulation of water balance in a condition of free access to water, inhibiting diuresis without affecting drinking
Dapiprazol prevents U50,488H-mediated suppression of preparatory components of drinking behavior in rats.
No full textIn a previous study, we found that the kappa opioid agonist U50,488H (U50) suppresses both appetitive and consummatory components of drinking behavior in rats trained to negotiate water in a straight runway. U50 also activates diuresis. Kappa opioid mechanisms could therefore play a dissipative role in the body's water balance. Since naloxone inhibits diuresis, but not hypodipsia produced by U50, these effects are probably mediated also by nonopioid mechanisms. In rats trained to negotiate water in a straight runway, we have studied the influence on the hypodipsic effects of U50 of the selective alpha-1 adrenoceptor antagonist dapiprazol (DAP), which we found to inhibit U50-mediated diuresis. When given alone, DAP (3 and 6 mg/kg IP) influenced neither running for water nor water intake; neither did it prevent the suppression of water intake produced by U50 (8 mg/kg IP) across the test. However, it did antagonize the U50-mediated slowing of running for water. Alpha-1 adrenoceptors thus appear to play a role in U50's effects on diuresis and the appetitive, but not consummatory, aspects of drinking
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
Delta types along the coast of the Italian Peninsula. Considerations on evolutive factors.
No full textVariations 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
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