1,720,987 research outputs found
Effect of hypophysectomy and growth hormone on tryptophan and serotonin metabolism
No full textThe presented study reports data on brain serotonin (5 HT) metabolism in 2 experimental conditions which have in common a lack of pituitary growth hormone (GH) and discusses also the effect of a GH replacement therapy. In hypophysectomized female rats or genetically dwarf mice, which have a more selective deficiency of GH, brain tryptophan (TP) and 5 hydroxyindoleacetic acid (5 HIAA) concentrations were significantly higher than in age matched controls. Brain levels of 5 HT were practically unchanged. A GH replacement therapy resulted in both hypophysectomized rats and dwarf mice in a significant reduction of brain TP and 5 HIAA concentrations. These results suggest that GH may exert an inhibitory action on 5 HT metabolism. Consonant with this view are the preliminary findings that in 7 individuals with elevated plasma GH levels for acromegaly, plasma TP levels were lower than in control subjects
Effect of reserpine on met-enkephalin-like material concentrations in the rat adrenal gland
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Chronic treatment with amphetamine. Effect on food intake and tissue levels of catecholamines
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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
Nefopam inhibits calcium influx, cGMP formation, and NMDA receptor-dependent neurotoxicity following activation of voltage sensitive calcium channels
No full textNefopam hydrochloride is a potent non sedative benzoxazocine analgesic that possesses a profile distinct from that of anti-inflammatory drugs. Previous evidence suggested a central action of nefopam but the detailed mechanism remains unclear. We have investigated the actions of nefopam on voltage sensitive calcium channels and calcium-mediated pathways. We found that nefopam prevented N-methyl-D-aspartate (NMDA)-mediated excitotoxicity following stimulation of L-type voltage sensitive calcium channels by the specific agonist BayK8644. Nefopam protection was concentration-dependent. 47 muM nefopam provided 50% protection while full neuroprotection was achieved at 100 muM nefopam. Neuroprotection was associated with a 73% reduction in the BayK8644-induced increase in intracellular calcium concentration. Nefopam also inhibited intracellular cGMP formation following BayK8644 in a concentration-dependent manner, 100 muM nefopam providing full inhibition of cGMP synthesis and 58 muM allowing 50% cGMP formation. Nefopam reduced NMDA receptor-mediated cGMP formation resulting from the release of glutamate following activation of channels by BayK8644. Finally, we also showed that nefopam effectively reduced cGMP formation following stimulation of cultures with domoic acid, while not providing neuroprotection against domoic acid. Thus, the novel action of nefopam we report here may be important both for its central analgesic effects and for its potential therapeutic use in neurological and neuropsychiatric disorders involving an excessive glutamate release
Effects of mazindol, a non-phenylethylamine anorexigenic agent, on biogenic amine levels and turnover rate
No full text1 Mazindol is a new anorexigenic agent which possesses a different chemical structure from that of phenylethylamines, but shows a pharmacological profile similar to that of (+)-amphetamine. 2 Mazindol neither altered whole brain monoamine levels (noradrenaline (NA), dopamine, 5-hydroxytryptamine (5-HT)) nor changed NA levels in the hypothalamus or dopamine levels in the caudate nucleus. 3 Mazindol enhanced dopamine turnover rate in the caudate nucleus, as shown by the increased rate of dopamine decline after blockade of catecholamine synthesis by alpha-methyl-p-tyrosine and decreased the conversion index of (3H)-tyrosine into brain NA. 4 Mazindol administration did not modify pargyline-induced decline of 5-hydroxyindoleacetic acid suggesting that 5-HT turnover is not altered by this drug
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