1,721,042 research outputs found
5-HT3 receptor involvement in descending reflex relaxation in the rabbit isolated distal colon
No full textIn whole segments of rabbit distal colon with mucosa removed, descending reflex relaxations of the circular muscle (descending inhibition) elicited by inflating (0.1-1 ml) an intraluminal balloon, were partially antagonized by 100 microM hexamethonium and the 5-HT3 receptor antagonist, ondansetron (3 microM), and abolished by 1 microM tetrodotoxin. The inhibitory effects of hexamethonium and ondansetron were additive. Conversely, hexamethonium (100 microM) and ondansetron (3 microM) failed to reduce electrically induced non-adrenergic non-cholinergic (NANC) relaxations of colonic circular muscle. It is concluded that interneuronally released acetylcholine and 5-hydroxytryptamine (5-HT) activate descending inhibitory pathways supplying the circular coat, via nicotinic and 5-HT3 receptors, respectively. This evidence suggests a functional involvement of 5-hydroxytryptaminergic transmission in the descending inhibition of rabbit colon
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
Esomeprazole dose-dependently counteracts glutathione deficiency and mitochondrial dysfunction induced by indomethacin in the rat gastric mucosa
No full text5-Hydroxytryptamine receptors that facilitate excitatory neuromuscular transmission in the guinea-pig isolated detrusor muscle
No full text1. In isolated detrusor strips from the guinea-pig urinary bladder, contractile responses to electrical field stimulation were mostly mediated by neurally released acetylcholine (ACh) and adenosine 5'-triphosphate (ATP). 2. 5-Hydroxytryptamine (5-HT) produced a concentration-dependent increase in the amplitude of stimulated detrusor strip contractions. The 5-HT concentration-response curve showed a biphasic profile: the high potency phase was obtained at sub-micromolar concentrations (10-300 nM), while the low potency phase in the range 1-30 microM. The maximum response of the first phase was 30% of the total 5-HT response. 3. Like 5-HT, the 5-HT3 receptor agonist, 2-methyl-5-hydroxytryptamine (2-methyl-5-HT: 0.3-100 microM), the 5-HT2 receptor agonist, (+/-)-1-(2,5-dimethoxy-4-iodophenyl)-2-aminopropane (DOI: 30 nM-3 microM) and the 5-HT4 receptor agonist, 5-methoxytryptamine (5-MeOT: 0.1-30 microM) potentiated, though with lower potency, detrusor contractions. The resulting concentration-response curves were monophasic in nature. 2-Methyl-5-HT had a maximum effect comparable to that of 5-HT. By contrast, the maximal effects of DOI and 5-MeOT were only 20% and 30% of that elicited by 30 microM 5-HT, respectively. 4. The 5-HT3 receptor antagonist, granisetron (0.3 microM) had no effect on the high potency phase, but caused a rightward parallel shift of the low potency phase of the 5-HT curve (pKB = 7.3). Granisetron(0.3 microM) antagonized with comparable affinity (pKB = 7.1) 5-HT-induced responses after pharmacological isolation of 5-HT3 receptors with the 5-HT1/5-HT2 receptor antagonist, methiothepin (0.3 microM) and the 5-HT4 receptor antagonist, GR 125487 (30 nM). Granisetron (0.1, 0.3 and 1 microM) competitively antagonized the potentiating effect of 2-methyl-5-HT with an estimated pA2 of 7.3.5. Methiothepin (0.3 microM) and the 5-HT2A receptor antagonist, ketanserin (0.3 microM) produced a slight inhibition of the first phase of the 5-HT curve. In the presence of ketanserin, an equimolar concentration of methiothepin was ineffective in further reducing the effect of 5-HT. Similarly, the 5-HT4 receptor antagonist, GR 125487 (30 nM) slightly inhibited the first phase of the 5-HT curve. Conversely, this phase was suppressed when detrusor strips were coincubated with ketanserin (or methiothepin) and GR125487.6. In a separate set of experiments, the interactions of 5-HT with either the purinergic or cholinergic components of excitatory neuromuscular transmission were investigated. In the presence of hyoscine(1 microM), 5-HT was mostly effective at sub-micromolar concentrations, while in the presence of the P2-purinoceptor antagonist, suramin (300 microM), 5-HT-induced potentiation was mainly obtained with micromolar concentrations.7. Thus, in electrically stimulated detrusor strips from guinea-pig, 5-HT potentiated excitatory neuromuscular transmission by activating at least three separate neural 5-HT receptors. These include the 5-HT2A and 5-HT4 receptors, which mediate the 5-HT high potency phase mainly by activation of purinergic transmission. On the other hand, the potentiating effect caused by micromolar concentrations of 5-HT mostly involves cholinergic transmission and is mediated by the 5-HT3 receptors
Expression of 5-hydroxytryptamine receptors in the guinea pig colon and their role in the control of propulsi+ve activity +and gut wall
No full textEsposizione inalatoria a persolfato d’ammonio: effetto sulle componenti del sistema NANC inibitorio della trachea di cavia
No full textTo evaluate the effect of ammonium persulphate (AP) inhalation on NANC inhibitory (i-NANC) neurotransmitters of guinea pig airways, we exposed eight guinea pigs to AP (1 mg/m3), by aerosol inhalation for 30 minutes daily for three weeks. Control animals inhaled saline aerosol. After the last exposure, the isolated trachea was mounted in an organ bath and electrically stimulated in the presence of hyoscine, piperoxane and propranolol. The i-NANC responses were evaluated as decreases in intraluminal pressure and expressed as area under the curve (AUC, Pa x seconds). The isolated tracheae were treated with a-chymotrypsin, L-NAME, zinc protoporphyrin IX and ODQ, that inhibit the production or action of the single neurotransmitters, like peptides, NO and CO. In the exposed individuals, the NANC relaxations were below 50%, as compared to controls (P < 0.01). NO and CO were the neurotransmitters responsible for all the i-NANC responses, in similar proportions either in exposed individuals or in controls. In conclusion, ammonium persulphate exposure impairs the i-NANC control of airway tone without specifically affecting any neurotransmitter
Esposizione inalatoria a ovalbumina in cavie sensibilizzate: effetto sulle risposte eccitatorie e inibitorie della trachea isolata
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