1,720,974 research outputs found
CCB-A and muscarinic receptor blockade differentially affect activity and organization of fed jejunal motility.
No full textEvidence for non-neurotensin receptor-mediated effects of xenin (1-25) - focus on intestinal microcirculation
No full textXenin (1-25) has been detected in various locations in mammalians. It has structural similarities with neurotensin and its intestinal effects are claimed to be mediated by neurotensin receptors. It has been shown to influence gastrointestinal motility. The effects of xenin (1-25) on intestinal microvascular perfusion after ischemia/reperfusion have not been investigated yet. Therefore, the superior mesenteric artery was clamped for 40 min in Wistar rats (n = 8). Ten minutes prior to reperfusion, intravenous infusion of xenin (1-25) (5 nmol/kg/h) was started. By means of intravital microscopy, microvascular perfusion in the mucosal layer was assessed. Animals (n = 8) with and without clamping of the superior mesenteric artery and infusion of the carrier solution served as controls. After ischemia/reperfusion, xenin (1-25) increased the density of perfused microvessels and the capillary red blood cell velocity compared to ischemic controls. Capillary red blood cell velocity was elevated (p < 0.05). Xenin (1-25) improved the heterogeneous distribution of mucosal blood flow during reperfusion demonstrated by an increase of both the perfusion index and the percentage of perfused microvessels. We conclude that the effects of xenin (1-25) on intestinal microcirculation are significantly different from those previously described for neurotensin. A more complex effector mechanism must be postulated that may involve other regulatory peptides and receptors. (C) 2002 Elsevier Science B.V All rights reserved
Differential effects of neurotensin and cholecystokinin on intestinal microcirculation after ischemia-reperfusion
No full textBackground. We investigated the effect of neurotensin and cholecystokinin (CCK) on intestinal microcirculation after ischemia-reperfusion. Method: Ischemia was induced in Wistar rats by occlusion of the superior mesenteric artery for 40 min. Ten minutes before reperfusion, infusion of either neurotensin or CCK was started. Afterwards. the microhemodynamics of the jejunum were examined by means of intravital microscopy. Results. Ischemia-reperfusion decreased functional capillary density from 873.4+/-18.1 to 362.5+/-8.3 cm(-1) and red blood cell velocity from 0.49+/-0.03 to 0.34+/-0.02 mm/s. Furthermore, leukocyte-endothelium interaction was increased. Neurotensin infusion significantly increased functional capillary density to 483.2+/-9.0 cm(-1) and red blood cell velocity to 0.69+/-0.01 mm/s in the mucosal capillaries compared with ischemic controls. Despite the amelioration of villus perfusion, the number of nonperfused villi significantly increased (11.8+/-3.6%) compared with ischemic controls. CCK infusion also resulted in a significant increase of functional capillary density (535.2+/-7.4 cm(-1)) and red blood cell velocity (0.67+/-0.01 mm/s). In contrast to neurotensin, the number of non-perfused villi was not increased (5.8+/-2.2%). Conclusion: We conclude that neurotensin further aggravates perfusion inhomogeneity and stasis when administered during the ischemic period. In contrast, CCK has no negative influence on perfusion homogeneity after ischemia-reperfusion. It may be superior to neurotensin in the reconstitution of normal microvascular perfusion patterns after ischemia-reperfusion
Impact of gastrin-releasing peptide on intestinal microcirculation after ischemia-reperfusion in rats
No full textWe investigated the effect of gastrin-releasing peptide (GRP) and its antagonist RC-3095 on intestinal microcirculation after ischemia-reperfusion. Intestinal ischemia was induced in female Wistar rats by occlusion of the superior mesenteric artery for 40 min. Ten minutes prior to reperfusion, infusion of GRP or RC-3095 was started. A jejunal segment was exteriorized and the microhemodynamics of the mucosa and submucosa were examined by intravital microscopy and compared both with normal and ischemic controls (without application of the regulatory peptide). Ischemia-reperfusion significantly decreased functional capillary density from 891.2 +/- 14.1 to 398.3 +/- 11.4 cm(-1). Capillary red blood cell velocity was reduced from 0.46 +/- 0.01 to 0.37 +/- 0.01 mm/s (p < 0.05). Furthermore, both sticking and rolling of leukocytes were enhanced. 3.4 +/- 1.1% of the villi were not perfused at all. GRP infusion reversed the microcirculatory ischemia-reperfusion injury by increasing functional capillary density to 669.8 +/- 8.3 cm(-1) and red blood cell velocity to 0.62 +/- 0.01 mm/s (p < 0.05). In addition, application of GRP resulted in a complete absence of stasis (0%) in the villi. Leukocyte-endothelium adherence remained unchanged when compared to the ischemic controls. In contrast, application of RC-3095 caused an aggravation of microcirculatory disturbances demonstrated by a markedly increased number of non-perfused villi (42.5 +/- 4.2%; p < 0.05 vs. ischemic controls) and a significantly reduced functional capillary density (346.2 +/- 8.4 cm(-1), p < 0.05 vs. ischemic controls). In addition, RC-3095 led to an increased permanent leukocyte adherence in postcapillary venules whereas rolling was significantly reduced when compared to normal controls. We conclude that GRP in pharmacological doses has a protective effect on intestinal microcirculation during reperfusion. Furthermore, these data suggest that endogenous GRP may play a decisive role in the maintenance of microvascular integrity during reperfusion. Copyright (C) 2000 S. Karger AG, Basel
Differential effects of neurotensin and cholecystokinin on intestinal microcirculation after ischemia-reperfusion
No full textBackground. We investigated the effect of neurotensin and cholecystokinin (CCK) on intestinal microcirculation after ischemia-reperfusion. Method: Ischemia was induced in Wistar rats by occlusion of the superior mesenteric artery for 40 min. Ten minutes before reperfusion, infusion of either neurotensin or CCK was started. Afterwards. the microhemodynamics of the jejunum were examined by means of intravital microscopy. Results. Ischemia-reperfusion decreased functional capillary density from 873.4+/-18.1 to 362.5+/-8.3 cm(-1) and red blood cell velocity from 0.49+/-0.03 to 0.34+/-0.02 mm/s. Furthermore, leukocyte-endothelium interaction was increased. Neurotensin infusion significantly increased functional capillary density to 483.2+/-9.0 cm(-1) and red blood cell velocity to 0.69+/-0.01 mm/s in the mucosal capillaries compared with ischemic controls. Despite the amelioration of villus perfusion, the number of nonperfused villi significantly increased (11.8+/-3.6%) compared with ischemic controls. CCK infusion also resulted in a significant increase of functional capillary density (535.2+/-7.4 cm(-1)) and red blood cell velocity (0.67+/-0.01 mm/s). In contrast to neurotensin, the number of non-perfused villi was not increased (5.8+/-2.2%). Conclusion: We conclude that neurotensin further aggravates perfusion inhomogeneity and stasis when administered during the ischemic period. In contrast, CCK has no negative influence on perfusion homogeneity after ischemia-reperfusion. It may be superior to neurotensin in the reconstitution of normal microvascular perfusion patterns after ischemia-reperfusion
CCB-A and muscarinic receptor blockade differentially affect activity and organization of fed jejunal motility.
No full text
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
- …
