1,721,014 research outputs found
Chronic treatment with fluoxetine decreases cerebral metabolic responses to the 5-HT(1A) agonist 8-hydroxy-2(di-N-propylamino)tetralin and increases those to the 5-HT(2A/2C) agonist 1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane and to the dopaminergic agonist apomorphine
No full textFluoxetine is a selective serotonin (5-HT) reuptake inhibitor that, when given chronically, alters different neurotransmitter systems. To assess functional changes occurring in the 5-HT and dopaminergic systems, we investigated the effects of 5-HT1A agonist 8-hydroxy-2(di-N- propylamino)tetralin (8-OH-DPAT), of the 5-HT2A/2C agonist 1-(2,5-dimethoxy-4-iodophenyl)-2- aminopropane (DOI) and of the dopamine D1/2 agonist apomorphine (APO) on behavior and on regional cerebral metabolic rates for glucose (rCMRglc) in rats pretreated for 3 weeks with saline or fluoxetine (8 mg/kg/day). Behavioral effects were assessed for 8-OH-DPAT by scoring the 5-HT syndrome, for DOI by counting head shakes and for APO with an activity monitor. rCMRglc were measured with quantitative autoradiographic [14C]2-deoxyglucose technique in 60 brain regions at 10 min after acute administration of 8-OH-DPAT 1 mg/kg, at 30 min after DOI 5 mg/kg or at 10 min after APO 1 mg/kg. Chronic fluoxetine did not alter the 5-HT syndrome by 8-OH-DPAT, decreased head shakes by DOI and enhanced hyperlocomotion by APO. 8-OH- DPAT produced rCMRglc increases in sensorimotor regions that were unaffected by fluoxetine pretreatment and diffuse metabolic decrements that were attenuated by fluoxetine in limbic and raphe areas (17% and 4% mean decreases, respectively, in saline control and fluoxetine- pretreated rats). DOI produced widespread rCMRglc declines that were intensified by fluoxetine (14% and 20% decreases, in control and fluoxetine rats). APO caused rCMRglc increases in 22 brain regions that were potentiated by fluoxetine in dopaminergic motor areas (10% and 25% increases, in control and fluoxetine rats). In conclusion, fluoxetine enhances 5-HT neurotransmission by blunting responsivity of 5-HT1A autoreceptors and increasing that of 5-HT2A/2C postsynaptic receptors and enhances dopaminergic D1/2 receptor neurotransmission
Effects of the loss of triose phosphate isomerase activity on carbon metabolism in Kluyveromyces lactis
No full textThe effect of the loss of triose phosphate isomerase activity on carbon metabolism in Kluyveromyces lactis was studied in batch and in continuous cultures. The KltpiI mutant was able to grow on media containing glucose as the sole carbon source both in batch and in continuous culture, unlike the corresponding S. cerevisiae mutant. In K. lactis tpiI mutant no glycerol production was detected in chemostat cultivations. DHAP accumulation triggers glycerol production only when glucose is the sole carbon source in excess. The analysis of the activities of some key enzymes of carbon metabolism shows that in chemostat cultivations on mixed-substrates the activities of enzymes involved in ethanol assimilation are higher both in K. lactis wild type and mutant strains than in S. cerevisiae
How physiological and cultural conditions influence heterologous protein production in Kluyveromyces lactis
No full textThe optimization and scale-up of a specific protein production process have to take into account cultural conditions as well as cell physiology of growth and influence of foreign protein expression on host cell metabolism. Growth on cheap substrates, efficient secretion ability and a weaker tendency to hypermannosilate proteins than S. cerevisiae, make K. lactis an excellent and well-accepted host for heterologous protein production, even for human use. A fairly good heterologous glucoamylase yield and the setting of the optimal conditions to produce it were obtained expressing the Arxula adeninivorans glucoamylase in a strain of K. lactis and its isogenic mutant, which seems to have higher secretion ability. We performed batch cultures of both strains to analyze the influence of different physiological and environmental parameters on glucoamylase production/secretion. Interestingly, the maintenance of pH in the range of neutrality causes the consumption of a larger amount of carbon source, a longer time of production and a better stability of the active form of the enzyme, thus increasing biomass and glucoamylase production. Furthermore, the enrichment of the culture medium adds up to the action of pH control, forcing the mutant production/secretion to higher levels
Cerebral metabolic effects of fluoxetine, fluvoxamine, paroxetine and sertraline in the conscious rat
No full textThe selective serotonin reuptake inhibitors (SSRI) exert a wide range of neurochemical and therapeutic activities. To investigate the neural effectors of SSRIs, we measured the regional cerebral metabolic rates for glucose (rCMRglc) in 56 brain regions of Fischer-344 rats 30 min after intraperitoneal injection of 0.4, 4 or 40 mg/kg of fluoxetine or fluvoxamine or after 4 mg/kg of paroxetine or sertraline. Both shared and drug- specific effects were detected. While all four SSRIs similarly reduced rCMRglc in a network of subcortical brain regions including the amygdala, locus coeruleus, basal ganglia and hypothalamic paraventricular nuclei, fluvoxamine, paroxetine and sertraline reduced rCMRglc also in the hippocampus and sertraline in the lateral habenula. The topography and the relation to dose of rCMRglc reductions by SSRIs differ from those of other classes of antidepressants, thus suggesting that SSRIs may specifically modulate brain areas involved in the physiological responses to stress
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
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