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Search Results: 1 - 10 of 1304 matches for " Cortez-Lugo "
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Niveles ambientales de las PM2.5 y distancia a una vía de alto tránsito en Ciudad Juárez, Chihuahua, México
Cortez-Lugo,Marlene; Holguín-Molina,Fernando; Flores-Luévano,Silvia; Romieu,Isabelle;
Salud Pública de México , 2004, DOI: 10.1590/S0036-36342004000600009
Abstract: objective: to assess pm2.5 levels at different distances from a heavy traffic road. material and methods: daily measurements of pm2.5 were taken between august 26 and 30, 2002, at different distances from tecnológico avenue in ciudad juarez, chihuahua, mexico. data analysis consisted of descriptive statistics for each distance and kruskal wallis and cross trend for ranks. results: we found a significantly decreasing trend of pm2.5 median levels with increasing distance from tecnológico avenue (p< 0.001). at 100 m distance from the avenue, pm2.5 levels decreased by 9.5 μg/m3 (40.6%) when compared to median levels registered on the avenue. the results showed a highly significant negative correlation between pm2.5 measurements and the distance from the avenue (r=-0.70, n=20 and p=0.0005). conclusions: pm2.5 median levels decreased significantly after 100 meters from heavy traffic roads. these results are of great relevance when assessing exposure to pm2.5 in epidemiological studies.
Evaluación de la calidad del aire interior y exterior en un jardín de ni os de la Ciudad de México
Cortez-Lugo Marlene,Mercado-García Adriana,Hernández-Avila Mauricio,Meneses-González Fernando
Salud Pública de México , 1998,
Abstract: Objetivo. Evaluar las diferencias en los niveles de ozono (O3) y bióxido de nitrógeno (NO2) en el interior y el exterior de una escuela en el suroeste de la Ciudad de México. Material y métodos. Se midieron diariamente estos contaminantes dentro y fuera del salón, de enero a abril de 1990, mediante monitoreo manual. Resultados. El NO2 adentro y afuera no sobrepasó la norma mexicana (0.21 ppm). El coeficiente de correlación entre las concentraciones máximas de NO2 de la estación de monitoreo local de la ciudad y el exterior del salón fue de 0.82 (p< 0.001). En relación con el O3, la concentración máxima fuera del salón fue de 0.29 ppm, y adentro, de 0.17 ppm (se colocaron en promedio por debajo de 0.06 ppm); entre el interior y el exterior del salón hubo una correlación de 0.72 y se observó que, por cada 1.7 ppm en el exterior, hay 1.0 ppm en el interior (p< 0.05). Conclusiones. Las mayores concentraciones de O3 en el exterior se presentaron entre las 11:00 y las 14:00 horas, por lo que se recomienda tener el descanso previamente a este horario.
Tendencia de los niveles de plomo en la atmósfera de la zona metropolitana de la Ciudad de México: 1988-1998
Cortez-Lugo,Marlene; Téllez-Rojo,Martha Ma; Gómez-Dantés,Héctor; Hernández-Avila,Mauricio;
Salud Pública de México , 2003, DOI: 10.1590/S0036-36342003000800005
Abstract: objective: to describe the trends in airborne lead levels and their association with the control measures implemented from 1988 to 1998 to phase out lead from gasoline that included the introduction of a lead-free gasoline and the use of catalytic converters in automobiles in mexico city. material and methods: data of atmospheric lead levels were obtained from the 9 field stations included in the local air quality monitoring network (rmma). trends for airborne lead are shown by monitor, monitoring area and for the entire metropolitan zone. analysis of data was performed using linear regression models including autocorrelation analysis. the models were validated by standard diagnostic techniques using student residuals analysis. results: the introduction of lead-free gasoline and the use of catalytic converters decreased the airborne lead levels by 23% while the slow elimination of lead from gasoline produced a cumulative decrease of 89% during the period and in all areas studied. conclusions: the strategy implemented to reduce sources of airborne lead pollution had an important impact on atmospheric lead levels. health risks of this environmental hazard are now primarily due to less important sources and to particular occupational exposures.
Evaluación de la calidad del aire interior y exterior en un jardín de ni?os de la Ciudad de México
Cortez-Lugo,Marlene; Mercado-García,Adriana; Hernández-Avila,Mauricio; Meneses-González,Fernando; Palazuelos-Rendón,Eduardo;
Salud Pública de México , 1998, DOI: 10.1590/S0036-36341998000500005
Abstract: objective. to evaluate the differences between indoor and outdoor ozone (o3) and nitrogen dioxide (no2) levels at a school located in southwest mexico city. material and methods. indoor and outdoor o3 and no2 levels were measured daily between january and april 1990 by manual monitoring. results. indoor and outdoor concentrations of nitrogen dioxide did not surpass the mexican standard (0.21 ppm). the correlation coefficient between maximum no2 concentrations measured by the city?s local monitoring station and those measured outside the classroom was 0.82 (p< 0.001). regarding ozone, its maximum outdoor concentration was 0.29 ppm and indoor concentrations were on average below 0.06 ppm (maximum = 0.17 ppm). the indoor/outdoor correlation coefficient was 0.72, and for every 1.7 ppm outside, there was 1.0 ppm inside (p< 0.05) conclusions. since the highest outdoors o3 concentrations were observed between 11:00 and 14:00 hrs, it is recommendable to have recess before this time.
Tendencia de los niveles de plomo en la atmósfera de la zona metropolitana de la Ciudad de México: 1988-1998
Cortez-Lugo Marlene,Téllez-Rojo Martha Ma,Gómez-Dantés Héctor,Hernández-Avila Mauricio
Salud Pública de México , 2003,
Abstract: OBJETIVO: Describir las tendencias del plomo atmosférico asociadas a la eliminación paulatina del plomo de la gasolina y el uso de convertidores catalíticos en el auto transporte de la Ciudad de México, de 1988 a 1998. MATERIAL Y MéTODOS: Estudio de series de tiempo que incluye las mediciones atmosféricas de plomo que se obtuvieron, entre 1988 y 1998, de nueve estaciones de la red manual de monitoreo atmosférico de la Ciudad de México. Las intervenciones evaluadas fueron la introducción de gasolina Magnasin, el uso de convertidores catalíticos y el descenso en la concentración de plomo hasta su eliminación total de la gasolina utilizada en los auto transportes. Se describen las tendencias de plomo por monitor, por zona geográfica, utilizando un modelo de regresión que incorpora una estructura de auto-correlación. RESULTADOS: La introducción de gasolina sin plomo y de los convertidores catalíticos se asoció con un descenso en la concentración de plomo atmosférico en 23%, la reducción paulatina del plomo en la gasolina ocasionó una reducción acumulada de 89% en todas las zonas estudiadas. CONCLUSIONES: La introducción de la gasolina sin plomo ha logrado abatir las concentraciones ambientales de este contaminante de una manera importante.
Assessment of personal exposure to ozone in asthmatic children residing in Mexico City
Ramírez-Aguilar,Matiana; Barraza-Villarreal,Albino; Moreno-Macías,Hortensia; Winer,Arthur M; Cicero-Fernández,Pablo; Vélez-Márquez,Ma. Guadalupe Doris; Cortez-Lugo,Marlene; Sienra-Monge,Juan José; Romieu,Isabelle;
Salud Pública de México , 2008, DOI: 10.1590/S0036-36342008000100013
Abstract: objective: a study was conducted to evaluate personal ozone exposure (o3p) among asthmatic children residing in mexico city. material and methods: a total of 158 chil-dren were recruited from december 1998 to april 2000. on average, three o3p measurements were obtained per child using passive badges. time-activity patterns were recorded in a diary. daily ambient ozone measurements (o3a) were obtained from the fixed station, according to children?s residence. levels of o3a and ozone, weighted by time spent in different micro-environments (o3w), were used as independent variables in order to model o3p concentrations using a mixed-effects model. results: mean o3p was 7.8 ppb. the main variables in the model were: time spent indoors, distance between residence and fixed station, follow-up group, and two interaction terms (overall r2=0.50, p<0.05). conclusions: the o3w concentrations can be used as a proxy for o3p, taking into account time-activity patterns and the place of residence of asthmatic mexican children.
Traffic-related air pollution and respiratory symptoms among asthmatic children, resident in Mexico City: the EVA cohort study
Maria-Consuelo Escamilla-Nu?ez, Albino Barraza-Villarreal, Leticia Hernandez-Cadena, Hortensia Moreno-Macias, Matiana Ramirez-Aguilar, Juan-Jose Sienra-Monge, Marlene Cortez-Lugo, Jose-Luis Texcalac, Blanca del Rio-Navarro, Isabelle Romieu
Respiratory Research , 2008, DOI: 10.1186/1465-9921-9-74
Abstract: A panel study was conducted among 147 asthmatic and 50 healthy children, who were followed up for an average of 22 weeks. Incidence density of coughing, wheezing and breathing difficulty was assessed by referring to daily records of symptoms and child's medication. The association between exposure to pollutants and occurrence of symptoms was evaluated using mixed-effect models with binary response and poisson regression.Wheezing was found to relate significantly to air pollutants: an increase of 17.4 μg/m3 (IQR) of PM2.5 (24-h average) was associated with an 8.8% increase (95% CI: 2.4% to 15.5%); an increase of 34 ppb (IQR) of NO2 (1-h maximum) was associated with an 9.1% increase (95% CI: 2.3% to16.4%) and an increase of 48 ppb (IQR) in O3 levels (1 hr maximum) to an increase of 10% (95% CI: 3.2% to 17.3%). Diesel-fueled motor vehicles were significantly associated with wheezing and bronchodilator use (IRR = 1.29; 95% CI: 1.03 to 1.62, and IRR = 1.32; 95% CI: 0.99 to 1.77, respectively, for an increase of 130 vehicles hourly, above the 24-hour average).Respiratory symptoms in asthmatic children were significantly associated with exposure to traffic exhaust, especially from natural gas and diesel-fueled vehicles.In Mexico City as well as in other cities, several studies have documented the adverse effect on respiratory health, caused by exposure to air pollutants [1]. This effect appears to be greater among asthmatic children, among whom increase in respiratory symptoms, acute decrease in lung function and and an increase in emergency visits have been reported [2-4]. In Mexico City, asthma exacerbation represents 7.8% of emergency room visits at the Hospital Infantil de Mexico "Federico Gomez", the largest children's hospital in Mexico City [5]. In 2003, the Ministry of Health reported that asthma was the 12th cause of death among children under 5 years of age, and the 20th cause of death among children between 5 and 14 years old [6].Experimental evidence in animals
Validation of the ISAAC Standardized Questionnaire Used by Schoolchildren from Mexicali, Baja California, Mexico
Karla Gorozave-Car,Albino Barraza-Villarreal,Consuelo Escamilla-Nú?ez,Leticia Hernandez-Cadena,Luz Helena Sanín-Aguirre,Marlene Cortez-Lugo,J. Blanco-Mu?oz,Horacio Riojas-Rodríguez,Hortensia Moreno-Macias,Isabelle Romieu
Epidemiology Research International , 2013, DOI: 10.1155/2013/490906
Abstract: Background. In Mexico, several studies have been conducted under the ISAAC methodology; nevertheless, no validation studies of the ISAAC questionnaire based on objective clinical testing in our country have been published. Aims of the Study. To validate the ISAAC questionnaire, used in a study of prevalence of allergic diseases, based on medical, respiratory, and allergic evaluations of schoolchildren being 11 to 16 years old in Mexicali, Mexico. Material and Methods. We conducted a cross-sectional study to validate the ISAAC questionnaire through the generation of an index (considered as gold standard) using pre- and postbronchodilator spirometry test, exhaled nitric oxide measurements, and atopic evaluations. 114 schoolchildren were included (23 asthmatics with respiratory symptoms and 91 nonasthmatics without respiratory symptoms) and we evaluated the sensitivity, specificity, and positive and negative predictive value of the questionnaire using discriminant analysis. Results. We observed sensitivity of 35.2% and specificity of 93.3% and the positive and negative predictive values were 82.6% and 61.5%, respectively. Conclusions. Our findings indicate that the ISAAC Mexican version questionnaire was less sensitive and more specific when compared to the gold standard; however, it is adequate and able to discriminate children with and without asthma and a useful tool to use in epidemiological studies. 1. Introduction Asthma, allergic rhinitis, and atopic dermatitis are three of the allergic diseases that most affect children worldwide [1–3]. Asthma is a multifactor disease characterized by chronic inflammation of the airways and a reversible obstruction of air flow. Concern about these diseases has arisen because of their increase over the years, with prevalence and mortality rates having increased worldwide [4]. The International Study of Asthma and Allergies in Childhood (ISAAC) methodology was established in 1990s [4]. This methodology is a useful and practical strategy to most effectively identify these types of affections in children. It has been used in many countries where different languages are spoken, as well as in countries where the language does not have a way to describe asthma symptoms. The ISAAC is designed with three phases. Phase I is designed to assess the basic prevalence and severity of asthma and other allergic diseases by administering target questionnaires. Phase II investigates possible risk factors related to these diseases and those suggested in phase I. Phase III repeats phase I to assess the prevalence tendency of these
Análisis de las principales causas de las inundaciones de septiembre de 2003 en el sur del estado de Guanajuato, México
Lucía Guadalupe Matías Ramírez,Oralia Oropeza Orozco,José Lugo Hubp,Miguel Cortez Vázquez
Investigaciones geográficas , 2007,
Abstract: Las precipitaciones intensas ocurridas en septiembre de 2003, provocaron que en la cuenca del Lerma varios ríos incrementaran su nivel, asimismo, las presas Allende y Solís alcanzaron su máxima capacidad, esto generó inundaciones severas en 17 de los 46 municipios en el sur del estado de Guanajuato. Ocurrieron seis decesos y hubo 18 000 damnificados, las pérdidas económicas ascendieron a más de 900 millones de pesos, el sector agropecuario fue el más afectado. Las precipitaciones y los escurrimientos se consideran las principales causas de las inundaciones de 2003. El análisis consistió en identificar los sistemas de tiempo que por la continuidad y persistencia produjeron lluvias extraordinarias. Se llevó a cabo una distribución espacial de la precipitación, el cálculo del periodo de retorno (Tr) y la frecuencia para estudiar el comportamiento de las tormentas de esa temporada y otras similares. Lo anterior se complementa con la construcción e interpretación de hidrogramas de uno de los principales ríos, con registros históricos y estudios previos de las características morfológicas de la región.Las inundaciones que ocurrieron en el sur del estado se deben a lluvias extraordinarias generadas por la interacción singular de tres sistemas de tiempo. La tormenta más severa alcanzó 98 mm de intensidad cuyo Tr se estimó en 50 a os, los valores acumulados durante 14 días fueron de más de 300 mm, los gastos medios diarios oscilaron entre los 180 y 200 m3/seg. Sin embargo, se han presentado avenidas importantes con precipitaciones del orden de los 50 a 70 mm, acumulados de 250 mm y gastos de 170 a 210 m3/seg. La morfología del terreno y los cambios de uso del suelo también favorecen estos fenómenos
Purification of the Drosophila melanogaster Proteins Inscuteable and Staufen Expressed in Escherichia coli  [PDF]
Xristo Zárate, Megan M. McEvoy, Teresa Vargas-Cortez, Jéssica J. Gómez-Lugo, Claudia J. Barahona, Elena Cantú- Cárdenas, Alberto Gómez -Trevi?o
Advances in Bioscience and Biotechnology (ABB) , 2015, DOI: 10.4236/abb.2015.67050
Abstract: The proteins Inscuteable and Staufen are key components during asymmetric cell division of neuroblasts for the development of Drosophila melanogaster. Expression and purification of both proteins has been a difficult task for structure-function studies. Based on codon optimization for protein expression in Escherichia coli, we have been able to produce, in soluble form, the C-terminal domains of Inscuteable and Staufen as chimeras with N-terminal maltose binding protein tag that contains a rigid linker between them for feasible crystallization. In addition, using an optimized synthetic gene, corresponding to the amino acid region 250 - 623 of Inscuteable fused to glutathione-S-transferase, low-scale expression experiments showed production of soluble protein. Finally, eukaryotic expression of Inscuteable in the methylothropic yeast Pichia pastoris failed to produce the Drosophila protein at detectable amounts, reinforcing the fact that E. coli still was the microorganism of choice for high-yield protein expression.
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