1,721,085 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Inhibition of [3H] dopamine uptake by flunarizine
No full textThe effect of different calcium channel blockers was studied on basal and cocaine-inhibited [3H]dopamine uptake in rat striatal synaptosomes. Isradipine (dihydropyridine calcium antagonist) and diltiazem (L-type calcium antagonist) were devoid of effect on [3H]dopamine uptake, while flunarizine (T-type calcium antagonist) inhibited [3H]dopamine uptake. Flunarizine inhibition was competitive and the inhibitory curve was biphasic with a Hill coefficient of 2.1. The high Hill number suggested a mechanism of positive cooperativity between two sites. Flunarizine inhibition showed a complex interaction with cocaine inhibition. While flunarizine at low concentrations interacts with a distinct site, at higher concentrations it interacts with the same site as cocaine. The relevance of this finding for the potentiation by flunarizine of cocaine-induced dopamine release in vivo is discussed
Differential effect of mu, delta, and kappa opioid agonists on adenylate cyclase activity
No full textD-Ala2, D-Leu5-enkephalin (DADLE) and dynorphin1-13 (Dyn1-13) inhibited striatal adenylate cyclase activity, both basal and dopamine-stimulated (DA), in rats and guinea pigs. The kappa-agonists bremazocine (BRZ), U-50,488 (trans-3,4-dicloro-N-methyl-N-[2-(1-pyrrolidinyl)-cyclohexyl]- benzeneacetamide), and U-69,593 (5 alpha, 7 alpha 8 beta)-(-)-N-methyl-N-(7-(1-pyrrolidinyl-1-oxaspiro (4.5)dec-8yl) benzeneacetamide inhibited only the basal adenylate cyclase activity, and such an effect was restricted to guinea pig striatum, an area known to contain a high density of kappa-binding sites. Moreover, BRZ was found to antagonize the inhibitory effect of both DADLE and Dyn1-13 in rat striatum
Opioid activity of lefetamine
No full textIn mice lefetamine, at the dose of 50 mg/kg produces motor hyperactivity and at the dose of 60 mg/kg produces analgesia. Both effects are abolished by naloxone. Displacement studies by using [3H]-Naloxone (Nx), [3H]-D-Ala-Met-Enkephalinamide (DAMA) and [3H]-Ethylketocyclazocine (EKC) showed that lefetamine competes with all these opiates with an affinity 50 times lower than that of morphine. The displacing capacity of lefetamine is decreased in the presence of 50 mM Na+. It is concluded that lefetamine is an opioid agonist
Failure by tricyclic antidepressants to affect the increase of dopamine extracellular concentrations produced by haloperidol in the caudate and accumbens nuclei of rats
No full textThe effect of different inhibitors of monoamine uptake on dopamine (DA) and dihydroxyphenylacetic acid (DOPAC) neuronal outflow was studied in the caudate and accumbens nuclei of rats, using the in vivo brain microdialysis method coupled to HPLC electrochemical detection. Under conditions of DA receptor blockade (as produced by the i.p. administration of 0.25 mg/kg of haloperidol), cocaine, GBR-12909 and d-amphetamine increased the concentration of extracellular DA beyond the effect produced by haloperidol alone in both areas studied. GBR-12909 and cocaine also increased DOPAC concentration, while d-amphetamine decreased it. On the contrary, the tricyclic antidepressants (TCA), desipramine and chloripramine, failed to modify the effect of haloperidol on DA and DOPAC neuronal outflow. It was concluded that: (a) nonadrenergic and serotonergic nerve terminals do not take up DA released from dopaminergic neurons, and (b) TCA have no effect on dopaminergic terminals
Desensitization of the D1 dopamine receptors in rats reproduces a model of escape deficit reverted by imipramine
No full textThe present study investigated the effect of long-term D1 dopamine receptor stimulation on an animal model of depression derived from the learned helplessness paradigm. 2. The model used is based on the escape deficit produced by a series of unavoidable shocks administered to rats 24 h before the test session. SKF 38393 administered acutely, completely prevented the development of animal hyporeactivity, while given repeatedly produced tolerance to its own protective effect. Moreover it also reduced the spontaneous escape reactivity of rats not exposed to the inescapable shocks. Animals chronically receiving SKF 38393 and showing a clearcut escape deficit, were treated daily with either imipramine, fluoxetine, or clomipramine. After 21 days of combined treatment the 3 antidepressants appeared equally effective in reverting the behavioral deficit. Moreover, long term administration of both imipramine or SKF 38393 down regulated D1 dopamine receptor number in the prefrontal cortex, while the association of the two drugs resulted in a receptor density similar to that of control rats. 3. The present results further support the crucial role played by D1 dopamine receptors in the control of animal reactivity to stressful stimuli and in the mechanism of action of imipramine. Moreover they show that the D1 dopamine receptor related escape deficit is sensitive also to compounds selectively acting through the serotonergic neuronal system
Variations on the Author
Get PDF“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
Under continuous dizocilpine infusion an N-methyl-D-aspartate receptor independent form of cocaine sensitization develops in rats
No full textN-methyl-D-aspartate (NMDA) receptor blockade is thought to prevent the development of cocaine-induced sensitization. Moreover, when cocaine is administered daily along with dizocilpine infusion to previously sensitized rats, the extinction of sensitization occurs. We report here two sets of experiments: (1) Rats were infused with dizocilpine through a subcutaneous mini-pump (0.1 mg/kg/day) during the induction of cocaine sensitization and, after 2 or 7 days of wash-out, were challenged with: cocaine, dizocilpine plus cocaine or 3-((+/-)2-carboxypiperazin-4-yl)-propyl-L-phosphonic acid (CPP) plus cocaine. Cocaine induced stereotypy scores significantly lower than that produced by the two drug combinations. Animals infused with dizocilpine alone did not present stereotypies when challenged either with dizocilpine or with dizocilpine plus cocaine. (2) Rats previously sensitized to cocaine received dizocilpine by infusion and daily cocaine treatments for a week. During the first days of infusion, sensitization appeared to be significantly decreased, but it resumed the initial intensity on days 6-7. After 2 and 9 days of wash-out, the expression of sensitization could be retrieved only by dizocilpine plus cocaine. Two distinct forms of sensitization to cocaine thus seem to exist: one dependent on and the second independent of NMDA receptor activity
- …
