Mexico City frequently experiences high levels of air pollution. This is due mainly to its topography and meteorology that suppress pollutant diffusion and dispersion. The atmospheric mixing is extremely poor, especially during the dry winter months. The levels of certain pollutants, such as particulate matter, are of concern since they have severe effects on public health. Visibility deterioration is one of the most noticeable effects in large cities. Biological effects of particulate matter on man and animals, ranging from mild eye irritation to death, have been reported. The effects depend on the size of the particles, their solubility, and toxicity. The main objective of this paper is to present the results of a chemical mass balance receptor model applied to a well-characterized data set of particulate matter collected in the Mexico City Metropolitan Area (MCMA). Samples of particulate matter were collected using a denuder and a Hi-Vol system for the respirable fraction and total suspended particles, respectively. In this paper the analysis of a database consisting of the chemical composition of 33 samples of respirable particulate matter (aerosols with diameter less than 2.5 μm) is presented. The 12-hour samples were acquired during day and night periods in a typical medium-income neighborhood from December 19, 1989 through February 5, 1990. The results show that the main contributors to suspended particles are vehicles without catalytic converters and heavy-duty diesel vehicles. The contribution of refineries, smelters, cement plants, resuspended dust, natural sources, and secondary aerosols were taken into account. In particular, the vehicles without catalytic converters represent the major contribution to PM2.5. They contribute with 50% during the day and 38% at night. Most of the source profiles were taken from the model library SPECIATE EPA. However, native profiles for soil, vehicles, and refinery were designed.

The present work reports on the free amino acids and volatile compounds in vinegars obtained from different types of raw materials (cider, white wine and red wine). Based on the amino acid contents of three types of vinegar and of the substrates from which they were obtained, the profile of the nitrogensupplying compounds and their uptake for the acetic acid bacteria were very similar. The most important amino acid in terms of supply and uptake was found to be L-leucine. L-Proline proved also important in the wine vinegars, however it was not depleted as L-leucine. The different acetification reactions involved were found to yield acetoin, and plus 1,1-diethoxyethane in the wine vinegars.

The water soluble protein fraction from lobster shell was investigated on the basis of solubility, foaming capacity. foam, emulsion and thermal stability and amino acid composition. The protein material has good functional properties with the exception of foam stability; the thermal stability and the essential amino acid indcx were low,. However, it may find interesting applications mainly on the basis of its functional properties and as a protein supply in such foods where a better balanced protein may result.

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ANTECEDENTES: La acumulación de aire en la cavidad pleural sin una patología aparente se denomina Neumotórax Espontáneo Primario (NEP), su causa principal es ruptura de bulas subpleurales (BS). Se presenta sobre todo en adolescentes, pero tiene baja incidencia de 3.4:100,000, por lo que el tratamiento se basa en guías con recomendaciones internacionales en adultos, series de casos o revisiones sistemáticas. OBJETIVO: Describir el manejo, experiencia quirúrgica, evolución y estancia hospitalaria en los pacientes con NEP por bulas en nuestro centro. CASO CLÍNICO: Se describe el manejo en 7 pacientes pediátricos, con edad promedio entre los 12 y 16 años, quienes presentaron neumotórax mayores. Se realizó manejo conservador con drenaje pleural con persistencia de fuga a las 48-72 horas, por lo que se decidió realizar resección de BS con engrapadora lineal por toracoscopia video-asistida (TVA), no se realizó pleurodesis mecánica o química por el riesgo de las complicaciones propias. A las 48 horas postquirúrgicas se retiró el drenaje pleural con remisión de la enfermedad y los pacientes se egresaron a las 72 horas postquirúrgicas. A los 8 meses de evolución persisten sin recaída. CONCLUSIÓN: El uso de manejo conservador en pacientes pediátricos sin importar el tamaño del neumotórax, no debe sobrepasar las 24-48 horas para el manejo quirúrgico, con ello se disminuye el tiempo de estancia hospitalaria y comorbilidades asociadas, además la resección de BS con engrapadora lineal mecánica sin pleurodesis es un tratamiento seguro hasta el momento sin datos de recidiva, como se comprueba en esta serie de casos. PALABRAS CLAVE: Neumotórax espontáneo primario, bulas subpleurales, toracoscopía video asistida