1,720,982 research outputs found
Alpha-1-adrenoceptor mediated formation of glycerophosphoinositol 4-phosphate in rat heart: possible role in the positive inotropic response
No full textIn the present study, we investigated whether phospholipase A2 (PLA2)/lysophospholipase activity producing glycerophosphoinositols from phosphoinositides was operating in rat heart and could be stimulated by alpha1-adrenergic agonists. PLA2/lysophospholipase activity was found in homogenates from rat right ventricles. The stimulation of PLA2/lysophospholipase activity by noradrenaline (NA) was prevented either by the alpha1-adrenergic antagonist prazosin or arachidonyl trifluoromethyl ketone, a selective inhibitor of the 85-110 kDa, sn-2-arachidonyl-specific cytosolic PLA2. The selective alpha1-adrenergic agonist phenylephrine induced a concentration- and time-dependent increase in glycerophosphoinositol (GroPIns) and glycerophosphoinositol 4-phosphate (GroPIns4P) in rat right ventricle slices prelabelled with D-myo-[3H]inositol. In electrically driven strips of rat right ventricles, prelabelled with D-myo-[3H]inositol, the positive inotropic effect induced by 20 microM NA in the presence of propranolol was accompanied by the formation of GroPIns and GroPIns4P. The concentration of the formed GroPIns4P (1.33+/-0.12 microM, N = 6) was similar to that previously reported to inhibit the Na+/Ca2+ exchanger in cardiac sarcolemmal vesicles (Luciani S, Antolini M, Bova S, Cargnelli G, Cusinato F, Debetto P, Trevisi L and Varotto R, Biochem Biophys Res Commun 206: 674-680, 1995). These findings show that the stimulation of alpha1-adrenoceptors in rat heart is followed by an increase in the formation of GroPIns4P, which may contribute to the positive inotropic effect of alpha1-adrenergic agonists by inhibition of the Na+/Ca2+ exchanger
Cardinal Ottoboni's liturgical scenographies and settings between 1689 and 1740
Full text linkL'opera raccoglie e illustra lo stato delle ricerche in corso nel Dottorato di Ricerca in Architettura, Storia e Progetto e presenta i principali ambiti di studio del dottorato stess
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
Uptake of chromate by rat thymocytes and role of glutathione in its cytoplasmic reduction.
No full text1. Chromate is taken up by rat thymocytes over a wide range of extracellular chromate concentrations (0.074 +/- 5.0 mM). 2. Chromate uptake followed Michaelis-Menten kinetics and was inhibited by 4-acetamido-4'-isothiocyano-stilbene-2,2'-disulphonic acid, suggesting that the anion carrier was responsible for the uptake by rat thymocytes. 3. The decrease in chromate uptake by the thiol(SH)-blocking agent diethyl maleate, the increased chromate uptake caused by the thiol-protecting agent dithiothreitol, and the reduction of glutathione/glutathione disulphide ratio indicated that the maintenance of the integrity of SH-groups greatly influenced the uptake and reduction of Cr(VI), and that glutathione may be responsible for the intracellular reduction of Cr(VI) to Cr(III)
Diamide: positive inotropic effect in isolated atria and inhibition of Na+/Ca2+ exchange in cardiomyocytes.
No full textThe influence of frequency of stimulation and external calcium on the positive inotropic response of guinea-pig left atria to diamide and the inhibitory action on Na+/Ca2+ exchange activity of rat cardiomyocytes by this oxidant of sulphhydryl groups have been investigated. Diamide (50-500 microM) induces a concentration-dependent positive inotropic effect which is more pronounced when atria are driven at 1.0 Hz rather than at 0.5 and 0.1 Hz, and are bathed in 2.72 mM rather than in 1.36 mM external calcium. A decrease in the positive inotropic effect at 35 degrees C with respect to 29 degrees C is also observed. In addition, diamide in positive inotropic concentrations (100-300 microM) significantly reduces Na+/Ca2+ exchange activity and cytoplasmic glutathione levels in adult rat cardiomyocytes. The thiol reducing agent dithiothreitol either reverses or prevents diamide effects both in isolated atria and cardiomyocytes, suggesting that the actions of diamide are correlated to its property to oxidize sulphhydryl groups to disulphides. In view of the functional importance of Na+/Ca2+ exchange in myocardial contractility, it is proposed that diamide may increase the heart force of contraction by an inhibition of the sarcolemmal Na+/Ca2+ exchange activity
Role of glucocorticoid receptors on dendritic spine plasticity in an Alzheimer’s disease animal model
No full textAIMS: Glucocorticoids hormones regulate stress response and are implicated in numerous diseases. The aim of our research is to assess the role of glucocorticoids in the pathogenesis of Alzheimer’s Disease (AD) and, in particular, to evaluate how the administration of agonists and antagonist of glucocorticoid receptors (GR) alter synaptic plasticity, causing a remodeling of dendritic spines in an AD mouse model (3xTg). METHOD: We administered either dexamethasone, an agonist of GR, or mifepristone, an antagonist of GR, to 6 month old 3xTg male mice. After perfusion with paraformaldehyde, brains were processed for Golgi Cox staining to highlight dendritic spines in a subset of neurons. We acquired images, reconstructed dendrites and, finally, calculated the dendritic spine density using the Imaris software (Bitplane). RESULTS: We found that dexamethasone causes a 23% reduction of spine density in CA1 region of hippocampus, whereas mifepristone resulted in a 14% significant increase, together with a modification of spine morphology. CONCLUSION: Dexamethasone-dependent reduction of spines is bigger than the one found in literature for treated wild type mice, suggesting a synergy between the molecular pathways leading to AD and the molecular action of glucocorticoids. Considering mifepristone treatment results, the blocking of GR could represent a possible therapeutic approach to slow down the progression of AD. In further studies, we will perform the experiments with dexamethasone and mifepristone to 10-11 months old 3xTg male mice to evaluate their effects on brains also in the late phase of pathology and we will investigate the molecular mechanism underlying the dendritic spine density changes
Effect of amiloride on sodium-calcium exchange activity in rat cardiac myocytes.
No full textThe effect of amiloride on Na+/Ca2+ exchange activity and adenylate energy charge in isolated rat cardiac myocytes has been studied. Amiloride inhibits Na+/Ca2+ exchange activity in rat cardiac myocytes with an IC50 of 1.76 mM when added to the external side of the cell membrane, whereas it is a weaker inhibitor when present at the cytoplasmic side. The adenylate energy charge in rat cardiac myocytes is unaffected by amiloride
- …
