ABSTRACT
BACKGROUND: Petcoke is a remnant of the oil refining process that contains Ni and other heavy metals. Undesired human exposure to these compounds may result from petcoke combustion in plants located in the vicinity of the cities. AIM: To compare levels of urinary Ni in schoolchildren residing in cities exposed and not exposed to petcoke pollution. MATERIAL AND METHODS: A cross sectional study was done in schoolchildren aged 7 to 8 years old in two cities in northern Chile: Mejillones (n = 59), near to a petcoke plant, and Tocopilla (n = 56) as the reference city. First, morning urinary samples were collected and urinary Ni was determined by Atomic Absorption Spectrometry. Socioeconomic and environmental exposure information of families was obtained applying a questionnaire to parents. Multiple linear regression was performed to identify other variables that may explain urinary Ni differences among the cities. RESULTS: Median level of Ni was higher in Mejillones (4.9 fig/L) than in Tocopilla (3.9 fig/L). Residing in the exposed city was the most important explaining factor (B = 0.26; IC 0.107 - 0.428). Additionally years of residency was associated with urinary Ni (B = 0.03; IC 0.004 - 0.060). CONCLUSIONS: Urinary Ni in schoolchildren is higher in the city exposed to petcoke emissions. The difference does not imply that there are concrete hazards for the population's health. However, it warns about the existence of a higher exposure in places where petcoke is used.
Subject(s)
Coke/toxicity , Environmental Health , Environmental Pollutants/urine , Environmental Pollution/adverse effects , Nickel/urine , Particulate Matter/chemistry , Child , Chile , Cross-Sectional Studies , Health Surveys , Humans , Nickel/toxicity , Risk Factors , Socioeconomic FactorsABSTRACT
Background: Petcoke is a remmant of the oil refiningprocess that contains Ni and other heavy metáis. Undesired human exposure to these compounds may result from petcoke combustión in plants located in the vicinity ofthe cities. Aim: To compare levéis of urinary Ni in schoolchildren residing in cities exposed and not exposed to petcoke pollution. Material and methods: A cross sectional study was done in schoolchildren aged 7 to 8 years oíd in two cities in northern Chile: Mejillones (n = 59), near to a petcoke plant and Tocopilla (n = 56) as the reference city. First, morning urinary samples were collected and urinary Ni was determined by Atomic Absorption Spectrometry. Socioeconomic and environmental exposure information of families was obtained applying a questionnaire to parents. Múltiple linear regression was performed to identify other variables that may explain urinary Ni differences among the cities. Results: Median level of Ni was higher in Mejillones (4.9 fig/L) than in Tocopilla (3.9 fig/L). Residing in the exposed city was the most important explaining factor (B = 0.26; IC 0.107 - 0.428). Additionally years of residency was associated with urinary Ni (B = 0.03; IC 0.004 - 0.060). Conclusions: Urinary Ni in schoolchildren is higher in the city exposed to petcoke emissions. The difference does not imply that there are concrete hazards for the population s health. However, it warns about the existence of a higher exposure in places where petcoke is used.
Subject(s)
Child , Humans , Coke/toxicity , Environmental Health , Environmental Pollutants/urine , Environmental Pollution/adverse effects , Nickel/urine , Particulate Matter/chemistry , Chile , Cross-Sectional Studies , Health Surveys , Nickel/toxicity , Risk Factors , Socioeconomic FactorsABSTRACT
En este número de C&T iniciamos una serie de artículos dedicados al tema de regresión y correlación. En este artículo se definen y explican los conceptos básicos de regresión lineal y correlación. Se explica cómo opera y cómo aplicar un modelo de regresión lineal simple, así como la interpretación de la información obtenida. Se detallan los supuestos que deben chequearse y cumplirse para que el modelo sea válido y la importancia de evaluar los datos en forma gráfica, antes de cualquier análisis multivariado. Este artículo no pretende reemplazar libros especializados en el tema, pero sí dar una visión general que permita entender cómo operan estos modelos y cuáles son sus virtudes y debilidades.
Subject(s)
Linear Models , Regression Analysis , Reproducibility of ResultsABSTRACT
No es raro disponer de información que no proviene de una muestra estrictamente aleatoria y se nos plantea el dilema de si es procedente o no enunciar conclusiones referidas a la población de la cual se extrajo esa muestra. Se discuten algunas consideraciones referentesa la decisión de extrapolar o no de la muestra a la población.
Subject(s)
Epidemiologic Research Design , Random AllocationABSTRACT
Background: We have shown numeric alterations such as hyperploidy and hypoploidy with loss of chromosome 17 in primary gastric cancer. This chromosome maps p53 suppressor gene that induces the transcription of genes related to cellular cycle control, DNA synthesis and repair, cellular differentiation and apoptosis. Aim: To analyze, at a molecular level, the possible alterations of p53 suppressor gene in samples of gastric cancer and non tumoral mucosa. Material and methods: Tissue samples of gastric carcinoma and non tumoral gastric mucosa coming from 26 patients subjected to a total gastrectomy were analyzed. The mutation of p53 suppressor gene exons 7 to 9 were determined using a conformational polymorphism analysis in single strands of the gene and indirect sequencing in some cases. Results: Alterations in p53 gene were found in 77 percent of tumoral and 19 percent of non tumoral samples. T insertions in codons 260, 317 and 321, G insertion in codon 328 and G-T transvertion in codon 302 were found. Aminoacid sequence analysis of p53 protein obtained with sequencing data showed that T insertion in codon 260 could translate three erroneous aminoacids after the mutation and produce a truncated protein due to the creation of a stop codon. No associations between alterations of p53 gene and clinical or pathological variables such as age, sex, tumor localization, histological type and presence of Iymph node metastases were observed
Subject(s)
Humans , Stomach Neoplasms/genetics , Adenocarcinoma/genetics , Genes, p53/genetics , Suppression, Genetic/genetics , Polymerase Chain Reaction , Polymorphism, Single-Stranded Conformational , Gastric Mucosa/pathologyABSTRACT
La exploración de los datos de 5380 niños menores de 10 años del universo muestral de la encuesta sobre el estado nutricional de la población chilena, mediante la aplicación del método de la segmentación conocido como Automactic Interaction Detection, permite modelar una función que explica los déficit de talla de los individuos en estudio, en relación a las variable socioeconómicas colectadas en el estudio. El resultado del proceso de segmentación sobre las variables predictoras, mostró el poder discriminatorio sólo de la escolaridad familiar, la promiscuidad, el combustible usado para cocinar y el ingreso, las que concurren a definir siete clases o segmentos terminales. Estas clases pueden considerarse como factores e indicadores socioeconómicos válidos del riesgo de déficit de talla de individuos. Su potencialidad evidente radica en la posibilidad de calificar rápidamente a individuos de nivel socioecionómicos desconocido, a través del diseño de instrumentos de fácil aplicación, toda vez que para determinar la pertenencia de un sujeto a una clase sólo se requiere de dos o tres características objetivas
Subject(s)
Humans , Male , Female , Infant , Child, Preschool , Failure to Thrive/epidemiology , Socioeconomic Factors , Weight by Age , Weight by Height , Multivariate Analysis , Chile/epidemiology , Nutritional Status , Predictive Value of Tests , Risk FactorsABSTRACT
La práctica común del uso de distintas mediciones antropmétricas como indicadores de la situación nutricional de individuos y población, condujo a evaluar la capacidad de éstos para satisfacer su condición de tal, estudiando su comportamiento ante factores genéticos y socioeconómicos involucrados en sistemas alimentarios nutricionales. El estudio utiliza una submuestra de 3645 individuos menores de 18 años obtenidos de los datos de la encuesta sobre el estado nutricional de la población chilena (ECEN) realizado en 1974-1975. El análisis del comportamiento de los indicadores frente a las variables estudiadas se presentan en diagramas de baricentros, los que grafican los valores promedios de dos varibles cuantitativas asociadas a las categorías de una o más variables cualitativas. La talla para la edad presenta un adecuada asociación con la talla de los padres, siendo ésta modificada por el índice socioeconómico, lo que no se observa con otros indicadores antropométricos estudiados