Purpose: To evaluate the concentration of allergic mediators in tears of children with seasonal allergic conjunctivitis (SAC) and perennial allergic conjunctivitis (PAC) compared with controls. Methods: Twenty children with allergic conjunctivitis (17 SAC, and 3 PAC) and sixteen healthy children were included in this study. Tear samples were collected using a Merocel sponge (Oasis, 0525), and immediately eluted by incubation in elution buffer and subsequent centrifugation at 20,000 rpm for 30 min at 4ºC. Concentrations of histamine (HIS), tryptase (TPS), eosinophil chemotactic factor (ECF), major basic protein (MBP), eosinophil cationic protein (ECP), eosinophil-derived neurotoxin (EDN), IgE and E-selectin were measured using enzyme linked immunosorbent assays (ELISA). Data were compared with the Mann-Whitney U test (P<.05), and multivariate analyses were also performed. Results: Tear levels of TPS (P=.014), MBP (P=.032), ECP (P=.0041), IgE (P=.014) and EDN (P=.00077) showed significant differences in children with SAC and PAC compared to controls. Conclusion: The simultaneous analyses of allergic mediators in the tears of children with SAC and PAC showed a significant elevated concentration in EDN, ECP and MBP in allergic group and decreased levels in IgE and TPS. Statistical analyses showed a diagnostic accuracy of 94.4% using the eight molecules panel.

Objetivo: Evaluar la concentración de diferentes moléculas mediadoras de alergia en lágrima de niños con conjuntivitis alérgica estacional (CAE) y conjuntivitis alérgica perenne (CAP) frente a controles. Métodos: Se incluyeron 20 niños con conjuntivitis alérgica (17 CAE y 3 CAP), y 16 niños sanos utilizados como controles. Las muestras de lágrima se obtuvieron mediante una hemosteta de acetato de polivinilo (OASIS, 0525) colocándola en el canto externo. Se eluyó la lágrima de la hemosteta utilizando un tampón y centrifugación a 20.000 rpm durante 30 minutos a 4ºC. Una vez cuantificadas las muestras se determinaron las concentraciones de histamina (HIS), triptasa (TPS), factor quimiotáctico del eosinófilo (ECF), proteína básica (MBP), proteína catiónica del eosinófilo (ECP), neurotoxina (EDN), IgE y E-selectina mediante la técnica ELISA (enzyme-linked immunosorbent assay). Los resultados se compararon con el test no paramétrico U de Mann-Whitney (p<0,05) y se realizaron análisis multivariantes mediante regresión logística. Resultados: Presentaron diferencias estadísticamente significativas la TPS (p=0.014), MBP (p=0,032), ECP (p=0,0041), IgE (p=0,014) y EDN (p=0,00077), cuando se comparó la lágrima de niños con CAE y CAP frente a la de niños control. Conclusiones: El análisis simultáneo de mediadores alérgicos en la lágrima de niños con CAE y CAP indica que existe una alteración en la lágrima referida principalmente a un aumento significativo de la concentración de EDN, ECP, MBP, y disminución de IgE y TPS. Los análisis estadísticos revelan una exactitud diagnóstica del 94,4% usando el panel de las 8 moléculas analizadas.

The kinetic parameters for the CO oxidation reaction using copper/alumina-modified ceria as catalysts were determined. The catalysts with different concentrations of the metals were prepared using impregnation methods. In addition, the reduction-oxidation behaviour of the catalysts were investigated by temperature-programmed reduction. The activity results show that the mechanism for CO oxidation is bifunctional : oxygen is activated on the anionic vacancies of ceria surface, while carbon monoxide is adsorbed preferentially on the higher oxidation copper site. Therefore, the reaction occurs on the interfacial active centers. Temperatures-programmed Reduction patterns show a higher disperdion when cerium oxide is present.

Ethane and propane oxidation on platinum and copper supported on Al2O3 and CeO2/Al2O3 catalysts were studied comparatively by examining reaction rates as a function of temperature. Results show that the addition of cerium oxide shifts the catalytic activity to higher temperatures. This negative influence is less pronounced in the case of supported copper samples, which on the basis of EPR and FTIR of adsorbed CO results is attributed to the low relative amount of this metal is in contact with ceria. The decrease in activity the presence of ceria might be due to changes in metal particle size or to the stabilization of the oxidized states of the metals, induced by their interactions with cerium oxide. The higher activity of platinum, in comparison with copper, is attributed to its higher reducibility along with an easier hydrocarbon activation on that metal.