Search results for "active"
showing 10 items of 5361 documents
Effects of Nrf2 deficiency on bone microarchitecture in an experimental model of osteoporosis
2014
Objective. Redox imbalance contributes to bone fragility. We have evaluated the in vivo role of nuclear factor erythroid derived 2-related factor-2 (Nrf2), an important regulator of cellular responses to oxidative stress, in bone metabolism using a model of postmenopausal osteoporosis. Methods. Ovariectomy was performed in both wild-type and mice deficient in Nrf2 (Nrf2-/-). Bone microarchitecture was analyzed by CT. Serum markers of bone metabolism were also measured. Reactive oxygen species production was determined using dihydrorhodamine 123. Results. Sham-operated or ovariectomized Nrf2 -/- mice exhibit a loss in trabecular bone mineral density in femur, accompanied by a reduction in co…
Characterisation of serotonin transport mechanisms in rainbow trout peripheral blood lymphocytes: role in PHA-induced lymphoproliferation
1999
Abstract AbstractIn this study we investigated the serotonin transport mechanisms in rainbow trout (Oncorhynchus mykiss) peripheral blood lymphocytes We have observed that the transport of serotonin is a membrane transport process that have the properties of a secondary active transport system The binding isotherm of [3H]-paroxetine a serotonin transport blocker demonstrated a high-affinity binding site with a positive type of cooperativity Hill coefficient being higher than unity Known specific inhibitors of the mammalian serotonin transporter significantly inhibited the uptake process in fish lymphocytes In order to demonstrate the physiological relevance of the serotonin transporter in T…
Sampling and analysis of pesticides in ambient air.
2008
Developments in the sampling and determination of pesticides in ambient air have been discussed and data on the occurrence of pesticides in atmosphere have been presented. Developments in active sampling methods were reviewed and the different materials used for trapping pesticides from gas and particulate phases were discussed. Likewise, the use and developments of passive air samplers were reviewed. This article pays special attention to the analysis of pesticides trapped from ambient air, and recapitulate the procedures for extraction, clean-up and determination of these substances. Improvements in sampling procedures, analytical methods and monitoring activities are necessary to advance…
Computational Analysis of the Active Control of Incompressible Airfoil Flutter Vibration Using a Piezoelectric V-Stack Actuator
2021
The flutter phenomenon is a potentially destructive aeroelastic vibration studied for the design of aircraft structures as it limits the flight envelope of the aircraft. The aim of this work is to propose a heuristic design of a piezoelectric actuator-based controller for flutter vibration suppression in order to extend the allowable speed range of the structure. Based on the numerical model of a three degrees of freedom (3DOF) airfoil and taking into account the FEM model of a V-stack piezoelectric actuator, a filtered PID controller is tuned using the population decline swarm optimizer PDSO algorithm, and gain scheduling (GS) of the controller parameters is used to make the control adapti…
Shock control bump design optimization on natural laminar aerofoil
2011
The chapter investigates Shock Control Bumps (SCB) on a Natural Laminar Flow (NLF) aerofoil; RAE 5243 for Active Flow Control (AFC). A SCB approach is used to decelerate supersonic flow on the suction/pressure sides of transonic aerofoil that leads delaying shock occurrence or weakening of shock strength. Such an AFC technique reduces significantly the total drag at transonic speeds. This chapter considers the SCB shape design optimisation at two boundary layer transition positions (0 and 45%) using an Euler software coupled with viscous boundary layer effects and robust Evolutionary Algorithms (EAs). The optimisation method is based on a canonical Evolution Strategy (ES) algorithm and inco…
Regulation of the effects of CYP2E1-induced oxidative stress by JNK signaling
2014
The generation of excessive amounts of reactive oxygen species (ROS) leads to cellular oxidative stress that underlies a variety of forms of hepatocyte injury and death including that from alcohol. Although ROS can induce cell damage through direct effects on cellular macromolecules, the injurious effects of ROS are mediated largely through changes in signal transduction pathways such as the mitogen-activated protein kinase c-Jun N-terminal kinase (JNK). In response to alcohol, hepatocytes have increased levels of the enzyme cytochrome P450 2E1 (CYP2E1) which generates an oxidant stress that promotes the development of alcoholic steatosis and liver injury. These effects are mediated in larg…
Mitochondrial function in liver disease.
2006
Oxidative stress is involved in the pathogenesis and progression of different liver diseases, such as alcoholic liver disease and biliary cirrhosis. The increased mitochondrial production of O2(-) at complexes I and III, and consequently of H2O2 and other reactive oxygen species (ROS), triggered by NADH overproduction seems the major cause of mitochondrial and cellular oxidative stress and damage in chronic alcoholism. The mitochondrial oxidative stress renders hepatocytes susceptible to ethanol- or acetaldehyde-induced mitochondrial membrane permeability transition (MMPT) and apoptosis. Nitrosative stress contributes to cell death by peroxynitrite formation. The expression of the death rec…
Mitochondrial aldehyde dehydrogenase (ALDH-2)--maker of and marker for nitrate tolerance in response to nitroglycerin treatment.
2008
The hemodynamic and anti-ischemic effects of nitroglycerin (GTN) are rapidly blunted as a result of the development of nitrate tolerance. Long-term nitrate treatment also is associated with decreased vascular responsiveness caused by changes in intrinsic mechanisms of the tolerant vasculature itself. According to the oxidative stress concept, increased vascular superoxide and peroxynitrite production as well as an increased sensitivity to vasoconstrictors secondary to activation of protein kinase C as well as vascular NADPH oxidases contribute to the development of tolerance. Recent experimental work has defined new tolerance mechanisms, including inhibition of the enzyme that bioactivates …
An Integral Version of Ćirić’s Fixed Point Theorem
2011
We establish a new fixed point theorem for mappings satisfying a general contractive condition of integral type. The presented theorem generalizes the well known Ciric's fixed point theorem [Lj. B. Ciric, Generalized contractions and fixed point theorems, Publ. Inst. Math. 12 (26) (1971) 19-26]. Some examples and applications are given.
Symmetries in Spaces, Symmetries in Listening
2018
Based on the importance of the concept of symmetry in French sociological aesthetics circa 1900, this chapter analyzes the convergence of theaters, musical form, and musical understanding. The analysis focuses on architectural shape, audience response, and the musical repertoire in the new theaters built in Barcelona (1847), Paris (1862), and Rome (1880). While these theaters were fashioned after the baroque form of the “teatro all’italiana” that prevailed in Italy, France, and Spain during the late nineteenth century, they provided huge spaces accommodating a socially mixed audience within an architecturally symmetrical form. Music critics often aligned acoustic sound waves with actual vis…