Search results for "contraction"
showing 10 items of 1092 documents
Regulation of endothelial nitric oxide synthase (eNOS) in myocardium subjected to cardioplegic arrest.
2009
BACKGROUND: Nitric oxide (NO) production by both coronary endothelial cells and cardiomyocytes is thought to play a significant role in myocardial pathophysiology following ischemia/reperfusion (I/R). METHODS: In thirteen pigs subjected to 1 hour cardioplegic arrest (CA) on CPB, left ventricular (LV) biopsies were collected prior to CPB (baseline), at 60 min CPA, at 15 and 30 min reperfusion on CPB, and at 120 min post CPB. LV specimens were immunocytochemically stained against phospho-eNOS Ser1177 , phospho-eNOS Thr495 , phosphorylated ERK1/2, and AKT/PKB. Four additional pigs without CA served as controls. Cardiomyocytes were quantitatively investigated using TV densitometry (gray units: …
Direct effect of cigarette smoke on human pulmonary artery tension.
2010
The effect of chronic cigarette smoke on pulmonary artery (PA) tension has been studied extensively; nevertheless, the direct effect of cigarette smoke is poorly understood. We investigated the direct effect of cigarette smoke extract (CSE) on PA tension in non-smokers, smokers, and COPD patients in vitro. PA samples from 35 patients who underwent lung resection were examined by measuring isometric tension in response to increasing serotonin concentrations. CSE dose dependently inhibited the response to serotonin in smokers and COPD patients, and to a lesser extent in non-smokers. CSE-induced relaxation was similarly inhibited by the nonspecific nitric oxide synthase (NOS) inhibitor l-NOARG…
Muscarinic M2 receptors in acetylcholine-isoproterenol functional antagonism in human isolated bronchus
2002
The muscarinic functional antagonism of isoproterenol relaxation and the contribution of muscarinic M2 receptors were examined in human isolated bronchus. In intact tissues, acetylcholine (ACh) precontraction decreased isoproterenol potency and maximal relaxation (−log EC50 shift = −1.49 ± 0.16 and Emax inhibition for 100 μM ACh = 30%) more than the same levels of histamine contraction. The M2receptor-selective antagonist methoctramine (1 μM) reduced this antagonism in ACh- but not histamine-contracted tissues. Similar results were obtained for forskolin-induced relaxation. After selective inactivation of M3 receptors with 4-diphenylacetoxy- N-(2-chloroethyl)piperadine hydrochloric acid (3…
phi-Best proximity point theorems and applications to variational inequality problems
2017
The main concern of this study is to introduce the notion of $$\varphi $$ -best proximity points and establish the existence and uniqueness of $$\varphi $$ -best proximity point for non-self mappings satisfying $$(F,\varphi )$$ -proximal and $$(F,\varphi )$$ -weak proximal contraction conditions in the context of complete metric spaces. Some examples are supplied to support the usability of our results. As applications of the obtained results, some new best proximity point results in partial metric spaces are presented. Furthermore, sufficient conditions to ensure the existence of a unique solution for a variational inequality problem are also discussed.
The class of F-contraction mappings with a measure of noncompactness
2017
In this chapter we review a class of contraction conditions, which are largely used to obtain interesting generalizations of the Banach fixed-point theorem in various abstract settings. We also present a new fixed-point existence result obtained by considering such a kind of contraction condition and a measure of noncompactness. Moreover, we show the applicability of these results in the theory of functional equations.
Common fixed points of mappings satisfying implicit relations in partial metric spaces
2013
Matthews, [S. G. Matthews, Partial metric topology, in: Proc. 8th Summer Conference on General Topology and Applications, in: Ann. New York Acad. Sci., vol. 728, 1994, pp. 183-197], introduced and studied the concept of partial metric space, as a part of the study of denotational semantics of dataflow networks. He also obtained a Banach type fixed point theorem on complete partial metric spaces. Very recently Berinde and Vetro, [V. Berinde, F. Vetro, Common fixed points of mappings satisfying implicit contractive conditions, Fixed Point Theory and Applications 2012, 2012:105], discussed, in the setting of metric and ordered metric spaces, coincidence point and common fixed point theorems fo…
Fixed points for asymptotic contractions of integral Meir-Keeler type
2012
In this paper we introduce the notion of asymptotic contraction of integral Meir-Keeler type on a metric space and we prove a theorem which ensures existence and uniqueness of fixed points for such contractions. This result generalizes some recent results in the literature.
A fixed point theorem for a Meir-Keeler type contraction through rational expression
2013
In this paper, we establish a new fixed point theorem for a Meir-Keeler type contraction through rational expression. The presented theorem is an extension of the result of Dass and Gupta (1975). Some applications to contractions of integral type are given.
Common fixed points for α-ψ-φ-contractions in generalized metric spaces
2014
We establish some common fixed point theorems for mappings satisfying an α-ψ-ϕcontractive condition in generalized metric spaces. Presented theorems extend and generalize manyexisting results in the literature.
 Erratum to “Common fixed points for α-ψ-φ-contractions in generalized metric spaces”
 In Example 1 of our paper [V. La Rosa, P. Vetro, Common fixed points for α-ψ-ϕcontractions in generalized metric spaces, Nonlinear Anal. Model. Control, 19(1):43–54, 2014] a generalized metric has been assumed. Nevertheless some mistakes have appeared in the statement. The aim of this note is to correct this situation.
Fixed points of α-type F-contractive mappings with an application to nonlinear fractional differential equation
2016
Abstract In this paper, we introduce new concepts of α-type F-contractive mappings which are essentially weaker than the class of F-contractive mappings given in [21, 22] and different from α-GF-contractions given in [8]. Then, sufficient conditions for the existence and uniqueness of fixed point are established for these new types of contractive mappings, in the setting of complete metric space. Consequently, the obtained results encompass various generalizations of the Banach contraction principle. Moreover, some examples and an application to nonlinear fractional differential equation are given to illustrate the usability of the new theory.