Search results for "Oxidation-Reduction"
showing 10 items of 689 documents
Nitric Oxide-Scavenging Properties of Some Chalcone Derivatives
2002
Abstract The implication of NO in many inflammatory diseases has been well documented. We have previously reported that some chalcone derivatives can control the iNOS pathway in inflammatory processes. In the present study, we have assessed the NO-scavenging capacity of three chalcone derivatives (CH8, CH11, and CH12) in a competitive assay with HbO2, a well-known physiologically relevant NO scavenger. Our data identify these chalcones as new NO scavengers. The estimated second-order rate constants (ks) for the reaction of the three derivatives with NO is in the same range as the value obtained for HbO2, with CH11 exerting the greatest effect. These results suggest an additional action of t…
Phosphorylation of the DNA repair protein APE/REF-1 by CKII affects redox regulation of AP-1
1999
The DNA repair protein apurinic endonuclease (APE/Ref-1) exerts several physiological functions such as cleavage of apurinic/apyrimidinic sites and redox regulation of the transcription factor AP-1, whose activation is part of the cellular response to DNA damaging treatments. Here we demonstrate that APE/Ref-1 is phosphorylated by casein kinase II (CKII). This was shown for both the recombinant APE/Ref-1 protein (Km=0.55 mM) and for APE/Ref-1 expressed in COS cells. Phosphorylation of APE/Ref-1 did not alter the repair activity of the enzyme, whereas it stimulated its redox capability towards AP-1, thus promoting DNA binding activity of AP-1. Inhibition of CKII mediated phosphorylation of A…
Tissue gradients of energy metabolites mirror oxygen tension gradients in a rat mammary carcinoma model
2001
Abstract Purpose: It has been shown that oxygen gradients exist in R3230AC tumors grown in window chambers. The fascial surface is better oxygenated than the tumor surface. The purpose of the present study was to determine whether gradients exist for energy metabolites and other end points related to oxygen transport. Methods and Materials: Imaging bioluminescence was used to measure ATP, glucose, and lactate in cryosections of R3230AC tumors. Mean vessel density and hypoxic tissue fraction were assessed using immunohistochemistry. Tumor redox ratio was assessed by redox ratio scanning. Results: Lactate content and hypoxic fraction increased, whereas ATP, glucose, redox ratio, and vessel de…
Tumor and its microenvironment: a synergistic interplay.
2013
The mutual and interdependent interaction between tumor and its microenvironment is a crucial topic in cancer research. Recently, it was reported that targeting stromal events could improve efficacies of current therapeutics and prevent metastatic spreading. Tumor microenvironment is a "complex network" of different cell types, soluble factors, signaling molecules and extracellular matrix components, which orchestrate the fate of tumor progression. As by definition, cancer stem cells (CSCs) are proposed to be the unique cell type able to maintain tumor mass and survive outside the primary tumor at metastatic sites. Being exposed to environmental stressors, including reactive oxygen species …
Carboxyamidotriazole inhibits cell growth of imatinib-resistant chronic myeloid leukaemia cells including T315I Bcr-Abl mutant by a redox-mediated me…
2010
Mutation of the Bcr–Abl oncoprotein is one of most frequent mechanisms by which chronic myelogenous leukemia (CML) cells become resistant to imatinib. Here, we show that treat- ment of cell lines harbouring wild type or mutant BCR–ABL with carboxyamidotriazole (CAI), a calcium influx and signal transduction inhibitor, inhibits cell growth, the expres- sion of Bcr–Abl and its downstream signalling, and induces apoptosis. Moreover, we show that CAI acts by increasing intracellular ROS. Clinically significant, CAI has also inhibitory effects on T315I Bcr–Abl mutant, a mutation that causes CML cells to become insensitive to imatinib and second generation abl kinase inhibitors.
QM/MM Determination of Kinetic Isotope Effects for COMT-Catalyzed Methyl Transfer Does Not Support Compression Hypothesis
2004
Secondary alpha-D3 kinetic isotope effects calculated by the hybrid AM1/TIP3P/CHARMM method for the reaction of S-adenosylmethionine with catecholate anion in aqueous solution and catalyzed by rat liver catechol O-methyltransferase at 298 K are 0.94 and 0.85, respectively, in good accord with experiment. The large inverse effect for the enzymatic reaction is not due to compression but arises from significant increases in the stretching and bending force constants involving the isotopically substituted atoms of the transferring methyl group as between the reactant complex and the transition structure, larger than for the reaction in water.
Analysis of Organic Aerosols Using a Micro-Orifice Volatilization Impactor Coupled to an Atmospheric-Pressure Chemical Ionization Mass Spectrometer
2014
We present the development and characterization of a combination of a micro-orifice volatilization impactor (MOVI) and an ion trap mass spectrometer (IT/MS) with an atmospheric-pressure chemical ionization (APCI) source. The MOVI is a multi-jet impactor with 100 nozzles, allowing the collection of aerosol particles by inertial impaction on a deposition plate. The pressure drop behind the nozzles is approximately 5%, resulting in a pressure of 96 kPa on the collection surface for ambient pressures of 101.3 kPa. The cut-point diameter (diameter of 50% collection efficiency) is at 0.13 μm for a sampling flow rate of 10 L min–1. After the collection step, aerosol particles are evaporated by he…
From molecular mechanisms to clinical management of antineoplastic drug-induced cardiovascular toxicity: A translational overview
2019
Significance: Antineoplastic therapies have significantly improved the prognosis of oncology patients. However, these treatments can bring to a higher incidence of side-effects, including the worrying cardiovascular toxicity (CTX). Recent Advances: Substantial evidence indicates multiple mechanisms of CTX, with redox mechanisms playing a key role. Recent data singled out mitochondria as key targets for antineoplastic drug-induced CTX; understanding the underlying mechanisms is, therefore, crucial for effective cardioprotection, without compromising the efficacy of anti-cancer treatments. Critical Issues: CTX can occur within a few days or many years after treatment. Type I CTX is associated…
A Thermophilic Tetramolecular G-Quadruplex/Hemin DNAzyme.
2017
International audience; The quadruplex-based DNAzyme system is one of the most useful artificial enzymes or catalysts; their unique properties make them reliable alternatives to proteins for performing catalytic transformation. The first prototype of a thermally stable DNAzyme system is presented. This thermophilic DNAzyme is capable of oxidizing substrates at high temperatures (up to 95 degrees C) and long reaction times (up to 18 h at 75 degrees C). The catalytic activity of the DNAzymes were investigated with the standard peroxidase-mimicking oxidation of 2,2'-azino-bis(3-ethylbenzothiozoline-6-sulfonic acid) (ABTS) by H2O2. The step-by-step design of this unique heat-activated G-quadrup…
Structural Characterization of Isomeric Dimers from the Oxidative Oligomerization of Catechol with a Biomimetic Catalyst
2007
In a previous paper, it has been reported about the formation of catechol di-, tri- and tetramers within an oxidative polymerization catalyzed by synthetic water-soluble iron-porphyrin as an efficient alternative to bio-labile natural peroxidase. It has also been demonstrated the occurrence of both C-C and C-O-C coupling mechanisms. However, since the coupling products were determined by mass spectroscopy, the exact bonding position could not have been precisely ascertained for the C-C bonded isomeric dimers that are the dominant products of catechol oligomerization. Therefore, here isolation and characterization of catechol isomeric dimers, obtained by oxidative coupling under the catalysi…