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Vasorelaxant effects induced by the antiangiogenic drug linomide in aortic and saphenous vein preparations of the rabbit
No full text1. Linomide (N-phenylmethyl-1,2-dihydro-4-hydroxyl-1-methyl-2-oxoquinoline-3-carb oxa mide) inhibits vascular proliferation and has been proposed as an antiangiogenic drug. We have investigated the vascular effect of linomide in rabbit aortic and saphenous vein ring preparations and in rat cultured vascular smooth muscle cells (VSMCs). 2. Linomide (25-300 micrograms ml-1) did not alter the basal tone of the preparations. The drug induced a concentration-dependent relaxant effect in aortic rings with endothelium, preconstricted by noradrenaline (NA), 5-hydroxytryptamine (5-HT) and by the thromboxane mimetic U46619. 3. The degree of relaxation induced by linomide was significantly reduced by exposure to the cyclooxygenase inhibitors indomethacin (3 microM) and acetylsalicylic acid (500 microM), and was not influenced by pretreatment with the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) (100 microM) in aortic rings with endothelium, preconstricted with NA. 4. Endothelium removal significantly reduced the relaxant response to linomide in aortic ring preparations. 5. A concentration-dependent relaxant response was observed also in rabbit saphenous vein preparations deprived of endothelium and preconstricted either by NA or U46619. The degree of relaxation obtained in a high potassium solution was consistently smaller than that observed in NA-pretreated venous preparations. 6. The vasorelaxant effect of linomide was consistently blunted by the adenylate cyclase inhibitor SQ 22536 (50 microM), both in intact aortic rings and in those deprived of endothelium. 7. In rat cultured vascular smooth muscle cells, linomide (100-200 micrograms ml-1) induced a significant increase in cyclic AMP levels, which was blocked by exposure to 50 microM SQ 22536. 8. In endothelium-deprived aortic ring preparations, the linomide-induced relaxant effect was greatly reduced in high potassium medium (KCl = 25 mM). Pretreatment with the ATP potassium channel inhibitor glibenclamide (3 microM) significantly reduced the linomide-induced relaxation. 9. The results show that linomide possesses a vasorelaxant effect which is attributable to both endothelium-dependent and -independent properties. While the former component of the drug's activity is apparently due to the release of a prostanoid from endothelial cells, the endothelium-independent mechanism involved in linomide relaxation is linked to cyclic AMP accumulation and to ATP-sensitive potassium channel activation in VSMCs
Thapsigargin inhibits the response to acetylcholine and substance P but does not interfere with the responses to endothelium-independent agents
No full textWe investigated the influence of the Ca(2+)-ATPase inhibitor thapsigargin (TG) on the vasorelaxant response to different endothelium-dependent and endothelium-independent relaxing agents in an isolated thoracic aorta preparation of the rabbit, precontracted by norepinephrine (NE). Pretreatment with 100 microM L-arginine methyl ester (L-NAME) an inhibitor of nitric oxide (NO) synthesis, completely prevented acetylcholine (ACh)-induced relaxation; the inactive stereoisomer D-NAME did not modify the effect of ACh. The exposure of the preparations to 1 microM TG induced a slowly developing slight increase in the basal tension during 30-min contact. The same concentration of TG also slightly reduced the response to the subsequent administration of NE. The antagonist effect of TG on the ACh response was concentration dependent in the range between 0.1 and 10 microM. A 30-min pretreatment with 1 microM TG appeared to be sufficient to induce a consistent antagonism of the ACh (0.01-10 microM) concentration-relaxant effect curve, since an increase to 60 min did not produce a further significant increment in the degree of the antagonist effect. The concentration-dependent relaxation induced by substance P (SP 0.1-3 nM) was also significantly antagonized by 1 microM TG. The effect of the calcium ionophore A23187 (0.01-1 microM) was reduced by the Ca(2+)-ATPase inhibitor only at the higher concentrations tested (0.3-1 microM). However, a 30-min contact time with 1 microM TG was completely ineffective in antagonizing the concentration-relaxant response curves to the two nitrovasodilators sodium nitroprusside (SNP 0.1-100 microM) and nitroglycerin (NTG 1-300 nM) and to the cyclic GMP analogue 8-Bromo-cyclic GMP (3-100 microM). The effects of the beta-adrenoceptor agonist isoprenaline (ISO 0.1-10 microM) and of the direct adenylate cyclase activator forskolin (FK 0.01-10 microM) were also completely unaffected by 1 microM TG. These results demonstrate that TG affects the response to agents that induce an endothelium-dependent relaxation through receptor-dependent calcium mobilization. However, they do not support the hypothesis that sarcoplasmic pump activity is essential for the development of a vasorelaxant response to endothelium-independent agents
Effects of substance P on mesenteric lymphatic contractility in the rat
No full textSubstance P (SP) is associated with lymphatic tissue and is a putative mediator of inflammation. The lymph pump is one of the major "safety factors" preventing edema and its activity is altered by inflammatory mediators. The impact of SP on lymphatics was studied in the rat mesentery.
METHODS AND RESULTS: Rats were prepared for in situ lymphatic observation using intravital videomicroscopic techniques. Sections of the small intestine and mesentery were exteriorized and superfused. Lymphatic diameters were measured and pumping activity was determined from the lymphatic diameter tracing. Lymph pump parameters evaluated included diastolic diameter, systolic diameter, contraction frequency, stroke volume, and lymph pump flow. After a control period, the tissues were exposed to SP (10(-9), 10(-8), 10(-7), 10(-6) M). SP reduced both diameters and increased contraction frequency in a concentration-dependent manner. SP (1.0 microM) produced the following changes (% of control): reductions in diastolic diameter (50%), systolic diameter (55%), and stroke volume (63%); a large increase in contraction frequency (661%); and a modest increase in lymph pump flow (44%). SP also stimulated vessels that were not contracting phasically to develop typical contraction patterns.
CONCLUSIONS: Although SP produced a tonic constriction of the lymphatics, lymph pump flow was maintained or slightly elevated via an increase in contraction frequency. SP also induced pumping activity in lymphatics that were previously quiescent, thereby further stimulating flow. These effects may serve to minimize the formation of edema in face of the inflammatory edemagenic conditions produced by SP
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
Peccatum pessimum. L’ira nella Moralis philosophia di Ruggero Bacone
Full text linkThe analysis of the moral doctrines contained in the Moralis philosophia of Roger Bacon reveals the central place reserved to the vice of anger. Bacon considers it a very serious sin, which goes against the human nature and makes many devastating effects on individuals and their social relations. Bacon’s moral doctrines are based on a source that has been recently rediscovered, Seneca’s De ira. Bacon is one of the first authors to quote extensively that work. Bacon’s enthusiasm for the Latin philosopher is the result of his conviction of the superiority of pagan philosophers over the Christians, especially in the field of ethics. The knowledge of the ancients, which is necessary for the life of individuals and for the proper function of institutions, is a duty for Christian thinkers
Essere è volere. Il problema dell'onnipotenza in Duns Scoto
Full text linkThe aim of this article is to examine Duns Scotus’ account of divine omnipotence. I shall firstly consider his doctrine of the objective possible and the distinction between logical potency and metaphysical potency. Secondly, by drawing on Scotus’ main texts on divine omnipotence (especially the Quodlibet VII), I will argue that, in his view, God’s omnipotence is not demonstrable, but at the same time is not an irrational concept, as Aristotle and many Medieval philosophi claimed. Finally, I shall discuss the connection between Scotus’ theory of being and that of the superiority of the will over the intellect
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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