RESUMO
Electron spin resonance (ESR) studies of the free radicals induced in gamma- or electron-irradiated sugar crystals were performed. The number of radicals increases linearly, pointing out that this material can be used as a dosimeter. The optical absorption studies show the presence of several distinctive bands in the infrared and UV region, whose intensity changes with the irradiation dose. An interpretation of these results in terms of the formation of free radicals and possible crosslinking along the sugar molecular chains is presented.
RESUMO
From the analysis of data of the Inspection/Maintenance (I/M) program, and of the long-term trend of ambient CO concentrations in Mexico City, it is inferred that three-way catalysts (TWCs) have a 45% efficiency, well below the expected 90% value. The most probable causes are sulfur poisoning, lead contamination, and ceramic breakage due to bumps and potholes on the streets. Also, we have found a ratio between the average daily peak value of atmospheric CO and gasoline consumption: (11 +/- 1) ppbCO/MLm (million liters of gasoline per month) in 1988 decaying to (10 +/- 1) in 1991 for Mexico City before the introduction of TWCs. In addition, we found a correlation between the monthly averages of CO daily peak and meteorological variables, explaining most of the seasonal changes using only the intensity of the inversion layer and surface wind speed.
Assuntos
Monóxido de Carbono/análise , Monitoramento Ambiental/métodos , Tempo (Meteorologia) , Movimentos do Ar , México , Veículos Automotores , Estações do AnoRESUMO
To study the rate of infection by Epstein Barr virus (EBV) in Santiago, Chile, the prevalence of antibody to the viral capsid antigen (VCA-IgG) was determined in a group of 663 helthy individuals grouped by age and socioeconomic level (SEL). In addition, several risk factors for infection were studied. VCA-IgG was determined by ELISA. The total prevalence was 76,6 percent. When grouped by age and SEL, 50 percent of the children from low and medium SEL had been already infected by the age two, compared to 5,9 percent in the high SEL (p<0.01). However, by age twenty, 90 percent of the total sample had already specific antibodies to EBV. Age and number of household members were positively associated with the infection. High socioeconomic level represented a delay factor in the acquisition of the virus, (p<0.01). These results show that EBV infection is frequent in Santiago, occurring early in childhood among medium and low SEL. Hence, the classical infectious mononucleosis should be recognized more frequently among adolescents and young adults belonging to high SEL, while the clinical spectrum of associated manifestations different from the typical mononucleosis syndrome should be investigated among those exposed in early age
Assuntos
Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Adolescente , Adulto , Pessoa de Meia-Idade , Herpesvirus Humano 4/isolamento & purificação , Mononucleose Infecciosa/epidemiologia , Imunoglobulina G/análise , Testes Sorológicos , Fatores de Risco , Distribuição por Idade , Fatores SocioeconômicosRESUMO
Se evaluó la exposición previa a legionella pneumophila de un grupo de 120 sujetos chilenos, sanos, menores de 20 años, estratificados según nivel socioeconómico. Las muestras de suero fueron analizadas, para la detección de anticuerpos de legionella pneumophila serogrupos 1 a 6, por técnica de inmunofluorescencia indirecta considerando positivos títulos iguales o mayores a 1:64. Doce de los 120 sujetos fueron positivos (10 por ciento); se observaron distintos grados de seroprevalencia según niveles socioeconómicos: 0/40 para el mas bajo; 2/40 (5 por ciento) en el nivel medio y 10/49 (25 por ciento) alto. El mayor título registrado fue 1:128. El nivel socioeconómico alto está asociado con la prevalencia mas alta de anticuerpos anti-legionella pneumophila en población chilena
Assuntos
Humanos , Masculino , Feminino , Lactente , Pré-Escolar , Adolescente , Adulto , Legionella pneumophila/patogenicidade , Doença dos Legionários/epidemiologia , Anticorpos/isolamento & purificação , Estudos Transversais , Fatores de Risco , Fatores SocioeconômicosRESUMO
Aún cuando los últimos años se ha empleado con frecuencia el lavado broncoalveolar (LBA) en el diagnóstico etiológico de neumonías bacterianas, el recuento que separa contaminación de infección es controvertido, habiéndose comunicado cifras entre 10(3) y 10(5) UFC/ml. Con el propósito, de comparar las muestras obtenidas mediante LBA y cateter telescópico protegido (CTP), efectuamos correlaciones entre los recuentos de microorganismos aerobios y anaerobios en 42 pacientes a los cuales se efectuó una broncoscopía por sospecha de infección bacteriana. La correlación entre los recuentos anaeróbicos de la misma especie fue elevada (r=0.937;p<0.001), siendo los cultivos de LBA en promedio 23.9 veces superior al de CTP. Los resultados para los microorganismos aerobios fueron similares; ya que también se observó una buena correlación (r=0.941;p<0.001), obteniéndose en promedio concentraciones 20.6 veces más altas en el LBA. Considerando que existen numerosas publicaciones que concuerdan en que el recuento significativo para CTP es de 10(3) UFC/ml, al usar esta cifra como patrón de comparación, nuestros resultados sugieren que el recuento equivalente para LBA es de 2x10(4) UFC/ml tanto para microorganismos aerobios como para anaerobios
