Different methods to analyze reactive oxygen species production

Inhalation Toxicology, 2001

The oxidative burst in circulating polymorphonuclear leukocytes (PMN) plays a fundamental role in pulmonary defense and injury. Flow cytometric techniques have been developed for quantitation of oxidative burst activity at the single cell level using 2',7'dichlorofluorescin (DCFH). However, the specific reactive oxidant species being measured using this method are not clearly defined. Isolated human PMN were loaded with DCFH diacetate, stimulated with phorbol myristate acetate (PMA) in the presence or absence of specific reagents, and analyzed using flow cytometry. Addition of PMA resulted in a 90-fold increase in the fluorescence intensity of DCFH-loaded neutrophils (p < .01). Inhibition of NADPH oxidase activity using a calmodulin antagonist (W-13) decreased PMA-induced DCFH oxidation by 70% (p < .05). Inhibition of nitric oxide synthase using N G-monomethyl-L-arginine (NMMA) did not significantly reduce DCFH oxidation, and did not alter the action of W-13. Addition of superoxide dismutase (SOD) had no effect, but catalase, with or without SOD, suppressed DCFH oxidation by 90% (p < .01). These data suggest that hydrogen peroxide, and not NO, is primarily responsible for the PMA-induced oxidation of DCFH in human PMN under these conditions.

Medical Science Monitor, 2012

Background: Airway inflammation represents the basis of respiratory allergic disease and is generally associated with increased oxidative stress. As a consequence of successful treatment leading to hyposenzibilization and remission of symptoms, decrease of reactive oxygen formation is expected. Material/Methods: This preliminary study evaluates the production of oxygen free radicals in white blood cells and changes in basic immunological parameters in a cohort of 50 patients (27 females and 23 males, age 14-48 years) with upper airway allergic inflammation caused by pollens, before and during specific immunotherapy. Results: We found an unexpected significant increase in the free radical concentration during and after treatment in comparison to values before the treatment and to the control group. Statistical analysis also found significant increase of IgG3 after initial treatment and also 1 year after allergen immunotherapy. Although there were similar trends in the elevated ROS and elevated IgG3, these were not statistically significant. Conclusions: We observed changes in oxidative mechanisms in white blood cells of patients treated with AIT. Allergen immunotherapy works at a multilayer level and influences airway inflammation as well as the protective antimicrobial defense in treated patients. Further studies for understanding the mechanisms involved in oxidative stress as well as for laboratory monitoring of therapeutic approaches in allergic diseases are needed.

American journal of blood research, 2017

Reactive oxygen species (ROS) are produced by numerous biological systems and by several phagocytes such as neutrophils and macrophages. ROS include mostly superoxide anion, hydrogen peroxide, singlet oxygen and hydroxyl radical, which are involved in a variety of biological processes such as immunity, inflammation, apoptosis and cell signaling. Thus, there is a need for a sensitive and reliable method to measure ROS. The luminol-amplified chemiluminescence technique is widely used to measure ROS production by neutrophils; however, it is unclear which ROS species are detected by this technique. In this study, we show that Xanthine/Xanthine oxidase (XXO), a known superoxide-producing system, stimulated a luminol-amplified chemiluminescence in the absence of horseradish peroxidase (HRPO), while the presence of HRPO enhanced the response. Both reactions were inhibited by superoxide dismutase (SOD), but not by catalase, confirming that superoxide anion, and not hydrogen peroxide, is the...

European Respiratory Journal, 1999

Increased production of oxidants subsequent to phagocyte stimulation has been associated with tissue damage in lung inflammatory disorders. The overall oxidative burden of the lung may vary with inflammatory cell composition.

Archives of Medical Research, 2005

Background. Oxidative stress mediated by reactive oxygen species (ROS) is recognized to contribute significantly to the inflammatory process of bronchial asthma (BA). These species are released into the airway by activated inflammatory cells such as leukocytes.

Free Radical Biology and Medicine, 2003

Asthma affects over 15 million individuals in the United States, with over 1.5 million emergency room visits, 500,000 hospitalizations, and 5500 deaths each year, many of which are children. Airway inflammation is the proximate cause of the recurrent episodes of airflow limitation in asthma. Research applying molecular biology, chemistry, and cell biology to human asthma and model systems of asthma over the last decade has revealed that numerous biologically active proinflammatory mediators lead to increased production of reactive oxygen species (ROS) and the gaseous molecule nitric oxide (NO). Persistently increased ROS and NO in asthma lead to reactive nitrogen species (RNS) formation and subsequent oxidation and nitration of proteins, which may cause alterations in protein function that are biologically relevant to airway injury/inflammation. Eosinophil peroxidase and myeloperoxidase, leukocyte-derived enzymes, amplify oxidative events and are another enzymatic source of NO-derived oxidants and nitrotyrosine formation in asthma. Concomitant with increased generation of oxidative and nitrosative molecules in asthma, loss of protective antioxidant defense, specifically superoxide dismutase (SOD), contributes to the overall toxic environment of the asthmatic airway. This review discusses the rapidly accruing data linking oxidative and nitrosative events as critical participants in the acute and chronic inflammation of asthmatic airways.

FEBS Letters, 1994

Nitric oxide ('NO) release, oxygen uptake and hydrogen peroxide (H202) production elicited by increasing phorbol12-myristate 13-acetate (PMA) concentrations were measured in human neutrophils. Half-maximal activities were sequentially elicited at about 0.0001-0.001 pg PMA/ml CNO) and O.OOl~.Ol pg PMA/ml (H,OJ. At saturated PMA concentrations, 'NO production, oxygen uptake and H,O, release were 0.56 ? 0.04, 3.32 f 0.52 and 1.19 f 0.17 nmol min-' 1 O6 cells-'. 'NO production accounts for about 30% of the total oxygen uptake. Luminol-dependent chemiluminescence, reported to detect NO reactions in other inflammatory cells, was also half-maximally activated at about 0.00-0.01 pg PMA/ml. Preincubation with A'"-monomethyl-L-arginine (L-NMMA) decreased 0, uptake and 'NO release but increased H,Oz production, while superoxide dismutase (SOD) increased 'NO detection by 30%. Chemiluminescence was also reduced by preincubation with L-NMMA and/or SOD. The results indicate that 'NO release is part of the integrated response of stimulated human neutrophils and that, in these cells, kinetics of-NO and O;-release favour the formation of other oxidants like peroxynitrite.

LA QUINTA DISCIPLINA en la práctica PETER SENGE La quinta disciplina en la práctica pág 1 <La historia del concepto de realimentación se describe más detalladamente en el libro de George P. Richardson, Feedback Thought in Social Science and Systems Theory (Filadelfia: University of Pennsylvania Press, 1991>

Revista Teias, 2023

La pandemia Covid-19 vino a poner en evidencia las grandes desigualdades en los sistemas educativos y las experiencias escolares. Por un lado, desnudó las diferencias materiales en equipos, condiciones de estudio, conectividad y posibilidades de participación y por otro la pobreza en el uso de las tecnologías como un recurso pedagógico y un mediador de la enseñanza. Desde hace mucho, la política educativa en México, como en muchas otras partes del mundo, exige a los maestros que usen cada vez más diversas tecnologías digitales en sus aulas. Nunca como ahora con el traslado de las clases a la casa se ha visto cómo el incorporar estas tecnologías a la enseñanza es un proceso complejo que abarca la redefinición de las relaciones en el aula, la reinterpretación del currículo y la expansión de la noción de alfabetización académica más allá de los textos escritos. Este trabajoanaliza cómo los maestros usan las tecnologías para responder y las aproveche para introducir formas novedosas para enseñar y aprender. Revisa datos recopilados antes de la pandemia para examinar los procesos de apropiación de las tecnologías para la enseñanza, y cómo aprenden en lapráctica. Encontramos que aprender a utilizar las tecnologías digitales en actividades educativas implica continuas aproximaciones a través de su uso para poder pensar en ellas como un entorno de aprendizaje y reformular prácticas establecidas.Palabras clave: Covid-19, tecnologías digitales, apropiación, práctica docente, aprender.

IEEE Antennas and Propagation Magazine, 2015

This paper presents a historical development of phased-array antennas as viewed by the authors. Arrays are another approach to high-gain antennas as contrasted with reflector antennas. They originated a little over 100 years ago and received little attention at first. WWII elevated their importance through use in air defense. Since then, the development of computers and solid-state devices has made arrays a very valuable tool in radio-frequency systems. Radio astronomy and defense applications will continue to push the state of the art for many years.