Search results for "upe"
showing 10 items of 7447 documents
Production of superoxide by human malignant melanoma cells.
1998
Metastasis is a complicated multi-step process involving interactions between tumour cells, the extracellular matrix and the vessel walls. Experimental observations suggest that leucocyte migration and function could be a suitable model in order to understand tumour cell dissemination. In the present report we show and quantify the production of free radicals by human malignant melanoma cells (St-ml12) by means of a spectrophotometrical method, using an enzyme immunoassay reader. Endothelial cells and activated polymorphonuclear leucocytes were used as controls. Melanoma cells without stimulants produced large amounts of superoxide anion at an increasing rate in relation to time, which coul…
Regulation of endothelial-type NO synthase expression in pathophysiology and in response to drugs.
2002
In many types of cardiovascular pathophysiology such as hypercholesterolemia and atherosclerosis, diabetes, cigarette smoking, or hypertension (with its sequelae stroke and heart failure) the expression of endothelial NO synthase (eNOS) is altered. Both up- and downregulation of eNOS have been observed, depending on the underlying disease. When eNOS is upregulated, the upregulation is often futile and goes along with a reduction in bioactive NO. This is due to an increased production of superoxide generated by NAD(P)H oxidase and by an uncoupled eNOS. A number of drugs with favorable effects on cardiovascular disease upregulate eNOS expression. The resulting increase in vascular NO producti…
Parthenolide induces superoxide anion production by stimulating EGF receptor in MDA-MB-231 breast cancer cells
2013
The sesquiterpene lactone parthenolide (PN) has recently attracted considerable attention because of its anti-microbial, anti-inflammatory and anticancer effects. However, the mechanism of its cytotoxic action on tumor cells remains scarcely defined. We recently provided evidence that the effect exerted by PN in MDA-MB-231 breast cancer cells was mediated by the production of reactive oxygen species (ROS). The present study shows that PN promoted the phosphorylation of EGF receptor (phospho-EGFR) at Tyr1173, an event which was observed already at 1 h of incubation with 25 µM PN and reached a peak at 8-16 h. This effect seemed to be a consequence of ROS production, because N-acetylcystein…
The oxygen radicals involved in the toxicity induced by parthenolide in MDA-MB-231 cells
2014
It has been shown that the sesquiterpene lactone parthenolide lowers the viability of MDA-MB-231 breast cancer cells, in correlation with oxidative stress. The present report examined the different radical species produced during parthenolide treatment and their possible role in the toxicity caused by the drug. Time course experiments showed that in the first phase of treatment (0-8 h), and in particular in the first 3 h, parthenolide induced dichlorofluorescein (DCF) signal in a large percentage of cells, while dihydroethidium (DHE) signal was not stimulated. Since the effect on DCF signal was suppressed by apocynin and diphenyleneiodonium (DPI), two inhibitors of NADPH oxidase (NOX), we s…
WIN 55,212-2, agonist of cannabinoid receptors, prevents amyloid β1-42 effects on astrocytes in primary culture
2015
Alzheimer's disease (AD), a neurodegenerative illness involving synaptic dysfunction with extracellular accumulation of Aβ1-42 toxic peptide, glial activation, inflammatory response and oxidative stress, can lead to neuronal death. Endogenous cannabinoid system is implicated in physiological and physiopathological events in central nervous system (CNS), and changes in this system are related to many human diseases, including AD. However, studies on the effects of cannabinoids on astrocytes functions are scarce. In primary cultured astrocytes we studied cellular viability using MTT assay. Inflammatory and oxidative stress mediators were determined by ELISA and Western-blot techniques both in…
Replica-exchange molecular dynamics simulation for supercooled liquids
2000
We investigate to what extend the replica-exchange Monte Carlo method is able to equilibrate a simple liquid in its supercooled state. We find that this method does indeed allow to generate accurately the canonical distribution function even at low temperatures and that its efficiency is about 10-100 times higher than the usual canonical molecular dynamics simulation.
Quantitative Analysis of Terpenic Compounds in Microsamples of Resins by Capillary Liquid Chromatography
2019
A method has been developed for the separation and quantification of terpenic compounds typically used as markers in the chemical characterization of resins based on capillary liquid chromatography coupled to UV detection. The sample treatment, separation and detection conditions have been optimized in order to analyze compounds of different polarities and volatilities in a single chromatographic run. The monoterpene limonene and the triterpenes lupeol, lupenone, &beta
Recent Advances in Sample Preparation for Pesticide Analysis
2012
Much progress has been made in pesticide analysis in the past decade. During this time, hyphenated techniques involving highly efficient separation with sensitive mass spectrometric detection have become the methods of choice. Even with such powerful instrumental techniques, a demanding task in pesticide residue analysis is the development of multiresidue methods for the determination of pesticides in air, water, soil, sediment, biota, and food. This chapter summarizes the analytical characteristics of the different methods of sample preparation for the determination of pesticide residues in a variety of food matrices, and surveys their recent applications in combination with gas chromatogr…
Mid-infrared supercontinuum generation in chalcogenide and telluride fibers for sensor devices
2019
This thesis reports on the progress made during my PhD concerning supercontinuum generation and its application in two types of materials: chalcogenide and tellurite glasses. Concerning the chalcogenide axis, two new arsenic-free compositions are developed: Ge20Se60Te20 and Ge20Se70Te10. Thermal and optical properties of these two glasses are studied and two types of fibers are manufactured: a step-index fiber and a suspended core fiber. The generation of supercontinuum in these two fibres, pumped by an optical parametric amplifier, gives competitive results compared to the current state of the art of supercontinuum generation in chalcogenide fibres. Supercontinuums widening between 2 and 1…
Microtomographic Quantification of Hydraulic Clay Mineral Displacement Effects During a CO2 Sequestration Experiment with Saline Aquifer Sandstone
2013
We combined a noninvasive tomographic imaging technique with an invasive open-system core-flooding experiment and compared the results of the pre- and postflooded states of an experimental sandstone core sample from an ongoing field trial for carbon dioxide geosequestration. For the experiment, a rock core sample of 80 mL volume was taken from the 629 m Stuttgart Formation storage domain of a saline sandstone aquifer at the CCS research pilot plant Ketzin, Germany. Supercritical carbon dioxide and synthetical brine were injected under in situ reservoir p/T-conditions at an average flow rate of 0.1 mL/min for 256 h. X-ray computed microtomographic imaging was carried out before and after the…