Association between life-course leisure-time physical activity and prostate cancer.

OBJECTIVE: To evaluate the association between life-course leisure-time physical activity (PA) and prostate cancer (PC) among males living in Mexico City. Materials and meth-ods. Information from 394 incident PC cases and 794 popula-tion controls matched by age (± 5 years), was analyzed. Using leisure-time PA information at different life stages, life-course PA patterns were constructed. The association between PA and PC was estimated using an unconditional logistic regres-sion model. RESULTS: Three life-course PA patterns were identified: low PA (71.0%), moderate PA (22.0%), and high PA (7.0%); this last pattern was characterized by higher levels and consistent PA practice. Compared with inactive males, those in the high PA pattern (OR: 0.50; 95%CI: 0.26-0.93) had significantly lower PC odds. CONCLUSION: Intense and regular PA could reduce the possibility of PC. These results are in accordance with PA World Health Organization rec-ommendations.

Association between life-course leisure-time physical activity and prostate cancer / Actividad física a lo largo de la vida y su asociación con cáncer de próstata

Abstract: Objective: To evaluate the association between life-course leisure-time physical activity (PA) and prostate cancer (PC) among males living in Mexico City. Materials and methods: Information from 394 incident PC cases and 794 population controls matched by age (± 5 years), was analyzed. Using leisure-time PA information at different life stages, life-course PA patterns were constructed. The association between PA and PC was estimated using an unconditional logistic regression model. Results: Three life-course PA patterns were identified: low PA (71.0%), moderate PA (22.0%), and high PA (7.0%); this last pattern was characterized by higher levels and consistent PA practice. Compared with inactive males, those in the high PA pattern (OR: 0.50; 95%CI: 0.26-0.93) had significantly lower PC odds. Conclusion: Intense and regular PA could reduce the possibility of PC. These results are in accordance with PA World Health Organization recommendations.

Resumen: Objetivo: Evaluar la asociación entre la actividad física (AF) en la vida y el cáncer de próstata (CP) en hombres. Material y métodos: Se analizó la AF de 394 casos incidentes de CP y 794 controles poblacionales pareados por edad (± 5 años). Se utilizó la información de AF en diferentes etapas para generar los patrones de AF a lo largo de la vida. La asociación entre AF y CP se estimó mediante regresión logística no condicionada. Resultados: Se identificaron tres patrones de AF: baja (71.0%), moderada (22.0%) y alta (7.0%); este último patrón se caracterizó por una AF consistentemente mayor a lo largo de la vida. Comparado con los hombres inactivos, aquéllos en el patrón de alta AF (RM= 0.50; IC95% = 0.26-0.93) presentaron menos posibilidades de tener CP. Conclusión: El papel protector de la AF parece estar en función de la intensidad y regularidad de su práctica y apoyan las recomendaciones de la OMS.

Determinants of folate and vitamin B12 plasma levels in the French E3N-EPIC cohort.

PURPOSE: Impaired B vitamin status has been identified as a risk factor for major chronic diseases. This study aims at examining the determinants of plasma folate and vitamin B12 concentrations, considering lifestyle factors and MTHFR polymorphisms. METHODS: A total of 988 women aged 40-65 years from the French E3N cohort were investigated. Intakes of folate and vitamin B12 were assessed using food frequency questionnaires, and plasma concentrations were measured by microbiological assay. Dietary scores were computed to summarize folate and vitamin B12 dietary sources. MTHFR-C677T and MTHFR-A1298C were determined by Kaspar assay. Pearson's partial correlation coefficients and multivariable linear regression models were used to assess correlations between main determinants and plasma folate and vitamin B12 levels. RESULTS: The partial correlation coefficient between dietary intakes and plasma folate was 0.19 (p value <0.001) and 0.08 (p value = 0.008) for vitamin B12. Dietary scores were the main determinant of B vitamin plasma concentrations with a percent change per unit increase of 12.64% (p value <0.001) for folate and 7.6% (p value <0.001) for vitamin B12. Homozygous (T/T) or heterozygous (C/T) women for MTHFR-C677T had lower plasma folate concentrations [C/T: -6.48% (p value = 0.038) and T/T: -15.89% (p value <0.001)] compared to women carrying the C/C genotype. Other determinants of B vitamin plasma concentration include: smoking status for folate, and age and hormone replacement therapy for vitamin B12. CONCLUSIONS: We confirmed previous findings on the role of diet as main determinant of folate and vitamin B12 plasma concentrations. However, the impact of genetic polymorphisms and lifestyle factors on plasma B vitamin concentrations should not be neglected.

Estrés oxidativo, función pulmonar y exposición a contaminantes atmosféricos en escolares mexicanos con y sin asma / Oxidative stress, lung function and exposure to air pollutants in Mexican schoolchildren with and without asthma

Resumen: Objetivo: Evaluar la asociación entre la exposición a contaminantes atmosféricos y marcadores de estrés oxidativo, por un lado, y la función pulmonar, por el otro, en escolares, con y sin asma, de las ciudades de Salamanca y León, en Guanajuato, México. Material y métodos: Se realizaron determinaciones de marcadores de estrés oxidativo y pruebas de función pulmonar en 314 escolares, y se obtuvo información sobre contaminantes atmosféricos (ozono, dióxido de azufre, monóxido de carbono y partículas menores de 2.5 µm y menores de 10 µm) de las estaciones de monitoreo correspondientes. Para evaluar la asociación se corrieron modelos de regresión lineal múltiple. Resultados: Con un día de retraso a la exposición a partículas menores de 10 µm (PM10), se observó un incremento de 0.09 pmol en los dienos conjugados entre niños asmáticos de Salamanca (p<0.05). La exposición a ozono durante el mismo día incrementó la concentración de lipo-hidroperóxidos en 4.38 nmol entre asmáticos de Salamanca, así como en 2.31 nmol por la exposición a PM10 para dos días de retraso (p<0.05). La capacidad vital forzada disminuyó 138 y 203 ml en niños sin asma, respectivamente, por la exposición a monóxido de carbono (p<0.05). Conclusiones: La exposición a contaminantes atmosféricos incrementa el estrés oxidativo y disminuye la función pulmonar en escolares con y sin asma.

Abstract: Objective. To assess the association between the air pollutants exposure on markers of oxidative stress and lung function in schoolchildren with and without asthma from Salamanca and Leon Guanajuato, Mexico. Materials and methods: We realized determinations of oxidative stress biomarkers and lung function tests in 314 schoolchildren. Information of air pollutants (O3, SO2, CO, PM2.5 and PM10) were obtained from monitoring stations and multiple linear regression models were run to assess the association. Results: An increase of 0.09 pmol in conjugated dienes was observed by exposure to PM10 lag 1 in asthmatics from Salamanca (p<0.05). The exposure to O3 during the same day increased the concentration of Lipohydroperoxides in 4.38 nmol in asthmatics of Salamanca, as well as in 2.31 nmol by exposure to PM10 lag 2 (p<0.05). The forced vital capacity decreased by 138 and 203 ml in children without asthma, respectively, due to exposure to carbon monoxide (p<0.05). Conclusions: Exposure to air pollutants increase oxidative stress and decreased lung function in schoolchildren, with and without asthma.

LEP rs7799039, LEPR rs1137101, and ADIPOQ rs2241766 and 1501299 Polymorphisms Are Associated With Obesity and Chemotherapy Response in Mexican Women With Breast Cancer.

BACKGROUND: Obesity plays a major role in the pathogenesis of breast cancer. Leptin (LEP) and adiponectin (ADIPOQ) are important in the regulation of adipose tissue. The response to cancer treatment depends on the histological and molecular tumor type, clinical stage, and genetic variability that might promote carcinogenic development. The aim of this study was to investigate the association between overweight/obesity and polymorphisms in the LEP (rs7799039), LEP receptor (LEPR; rs1137101), and ADIPOQ genes (rs2241766, rs1501299) with the response to breast cancer treatment in Mexican women. PATIENTS AND METHODS: A sample of 177 patients with primary breast cancer (stage I-III) and who received neoadjuvant therapy were included. Polymorphisms were genotyped and their serum LEP concentrations (n = 59) were quantified. RESULTS: The patients' median age was 53.1 years, the frequency of overweight and obesity was 57 and 84 patients, respectively, 117 were postmenopausal, and 64 of the patients did not respond to chemotherapy. An association of the LEP rs7799039, LEPR rs1137101, and ADIPOQ rs1501299 polymorphisms with overweight/obesity was found. The patients who did not respond to treatment were more frequently obese, at clinical stage III, had metastases, and high levels of glucose. Moreover, in samples that were positive for estrogen receptor, higher levels of LEP were found, and in wild type genotypes for LEP rs7799039 and LEPR rs1137101. CONCLUSION: There was a direct association between the polymorphisms in LEP rs7799039 and ADIPOQ rs1501299 with overweight/obesity, and these genotypes affected the response to chemotherapeutic treatment, suggesting that an obesogenic microenvironment is more favorable for tumoral progression.

Metabolic Syndrome and Mammographic Density in Premenopausal Chilean Women.

BACKGROUND: Metabolic syndrome (MetS) has been previously associated with an increased risk of breast cancer in postmenopausal women. Mammographic density (MD) is a marker of breast cancer risk. There is little evidence of an association between MetS and MD in premenopausal women. METHODS: Through a cross-sectional study, we evaluated 364 premenopausal Chilean women in which we measured anthropometric, blood pressure, and metabolic markers. MetS and its components were defined according to the National Cholesterol Education Program Adult Treatment Plan III criteria. We estimated MD by absolute dense volume (ADV, cm3), nondense volume (NDV, cm3), and percentage of dense volume (PDV, %). The relationship between MetS and MD was assessed by linear regression models. RESULTS: After adjusting for sociodemographic and gyneco-obstetrics variables, nonsignificant association was found between MetS and ADV (log ß = 0.10; 95%CI: -0.01, 0.21). However, abdominal obesity, high triglycerides, and number of components of MetS were directly related to higher ADV (P < 0.05). CONCLUSION: Our results showed no association between MetS and ADV; nevertheless, abdominal obesity and triglycerides were related to higher ADV. If MD could be modifiable through nutritional factors, it would open new perspectives for the prevention of breast cancer through obesity prevention strategies at population level.

Epigenetic Signatures of Cigarette Smoking.

BACKGROUND: DNA methylation leaves a long-term signature of smoking exposure and is one potential mechanism by which tobacco exposure predisposes to adverse health outcomes, such as cancers, osteoporosis, lung, and cardiovascular disorders. METHODS AND RESULTS: To comprehensively determine the association between cigarette smoking and DNA methylation, we conducted a meta-analysis of genome-wide DNA methylation assessed using the Illumina BeadChip 450K array on 15 907 blood-derived DNA samples from participants in 16 cohorts (including 2433 current, 6518 former, and 6956 never smokers). Comparing current versus never smokers, 2623 cytosine-phosphate-guanine sites (CpGs), annotated to 1405 genes, were statistically significantly differentially methylated at Bonferroni threshold of P<1×10-7 (18 760 CpGs at false discovery rate <0.05). Genes annotated to these CpGs were enriched for associations with several smoking-related traits in genome-wide studies including pulmonary function, cancers, inflammatory diseases, and heart disease. Comparing former versus never smokers, 185 of the CpGs that differed between current and never smokers were significant P<1×10-7 (2623 CpGs at false discovery rate <0.05), indicating a pattern of persistent altered methylation, with attenuation, after smoking cessation. Transcriptomic integration identified effects on gene expression at many differentially methylated CpGs. CONCLUSIONS: Cigarette smoking has a broad impact on genome-wide methylation that, at many loci, persists many years after smoking cessation. Many of the differentially methylated genes were novel genes with respect to biological effects of smoking and might represent therapeutic targets for prevention or treatment of tobacco-related diseases. Methylation at these sites could also serve as sensitive and stable biomarkers of lifetime exposure to tobacco smoke.

Genome-wide association study of colorectal cancer in Hispanics.

Genome-wide association studies (GWAS) have identified 58 susceptibility alleles across 37 regions associated with the risk of colorectal cancer (CRC) with P < 5×10(-8) Most studies have been conducted in non-Hispanic whites and East Asians; however, the generalizability of these findings and the potential for ethnic-specific risk variation in Hispanic and Latino (HL) individuals have been largely understudied. We describe the first GWAS of common genetic variation contributing to CRC risk in HL (1611 CRC cases and 4330 controls). We also examine known susceptibility alleles and implement imputation-based fine-mapping to identify potential ethnicity-specific association signals in known risk regions. We discovered 17 variants across 4 independent regions that merit further investigation due to suggestive CRC associations (P < 1×10(-6)) at 1p34.3 (rs7528276; Odds Ratio (OR) = 1.86 [95% confidence interval (CI): 1.47-2.36); P = 2.5×10(-7)], 2q23.3 (rs1367374; OR = 1.37 (95% CI: 1.21-1.55); P = 4.0×10(-7)), 14q24.2 (rs143046984; OR = 1.65 (95% CI: 1.36-2.01); P = 4.1×10(-7)) and 16q12.2 [rs142319636; OR = 1.69 (95% CI: 1.37-2.08); P=7.8×10(-7)]. Among the 57 previously published CRC susceptibility alleles with minor allele frequency ≥1%, 76.5% of SNPs had a consistent direction of effect and 19 (33.3%) were nominally statistically significant (P < 0.05). Further, rs185423955 and rs60892987 were identified as novel secondary susceptibility variants at 3q26.2 (P = 5.3×10(-5)) and 11q12.2 (P = 6.8×10(-5)), respectively. Our findings demonstrate the importance of fine mapping in HL. These results are informative for variant prioritization in functional studies and future risk prediction modeling in minority populations.

Effects of antioxidant supplements and nutrients on patients with asthma and allergies.

Asthma and allergic diseases have become a worldwide public health concern because of their increased prevalence. Despite decades of research on risk factors, the causes of these disorders are poorly understood. They are thought to develop through complex interactions between genetic and environmental factors. Because pulmonary and systemic oxidative stress increase inflammatory responses relevant to asthma and allergy, dietary or vitamin supplementation with antioxidants (a broad and varied category) has been proposed as an approach to reducing asthma incidence or morbidity. Meta-analyses of observational epidemiologic studies of variable methodological quality suggest associations of relatively low dietary intake of antioxidants and higher asthma and allergy prevalence. However, there have been few longitudinal studies of maternal or child dietary or vitamin/supplement antioxidant intake and asthma/allergy development. Moreover, there are no clinical trial data to support the use of dietary antioxidants or supplements to prevent asthma or allergy. A few small clinical trials suggest that specific antioxidants from diet or vitamin supplements might improve asthma control or lung function in asthmatic children or adults. Studies suggest that responses to antioxidants might be modified by life stage, genetic susceptibility, and environmental sources of oxidative stress. Large trials of antioxidant vitamin supplementation to prevent cancer suggest an increase in overall mortality with antioxidant vitamin supplementation, at least in populations with sufficient dietary antioxidant intake. This cautionary experience suggests that future trials to assess whether antioxidants reduce asthma incidence or improve asthma control should focus on supplementation of dietary sources of antioxidants. The potential benefits and risks of trials of vitamin supplements might be considered in special situations in which vulnerable populations have marked deficiency in dietary antioxidants, poor access to dietary antioxidants, and high exposure to environmental sources of oxidants.

Association between rs2981582 polymorphism in the FGFR2 gene and the risk of breast cancer in Mexican women.

BACKGROUND AND AIMS: The rs2981582 single nucleotide polymorphism in the fibroblast growth factor receptor 2 gene has been consistently associated with an increased risk of breast cancer. We evaluated the effect of rs2981582 polymorphism in the FGFR2 gene on the risk of breast cancer and its interaction with non-genetic risk factors. METHODS: A population-based case-control study was conducted in Mexico. Data from 687 cases and 907 controls were analyzed. RESULTS: The T allele of the rs2981582 polymorphism was associated with an increased risk of breast cancer (ORper allele = 1.24, 95% CI 1.06-1.46). There was also an interaction between this polymorphism and alcohol consumption (p = 0.043). The effect of alcohol consumption on the risk of breast cancer varied according to the allelic variants of the rs2981582 polymorphism in the FGFR2 gene: OR = 3.97 (95% CI 2.10-7.49), OR = 2.01 (95% CI 1.23-3.29) and OR = 1.21 (95% CI 0.48-3.05) for genotypes CC, CT and TT, respectively. CONCLUSIONS: This is the first study exploring the association between rs2981582 polymorphism in the FGFR2 gene and breast cancer risk in Mexican women. The interaction found may be of great public health interest because alcohol consumption is a modifiable breast cancer risk factor. Therefore, replication of this finding is of foremost importance.

Consumo de alimentos y asma en niños escolares de Cuernavaca / Food consumption and asthma in school children in Cuernavaca, Morelos, Mexico

OBJETIVO:Evaluar la relación entre la dieta y el desarrollo de asma y rinitis alérgica en escolares de Cuernavaca, Morelos, México. MATERIAL Y MÉTODOS: Se aplicó el cuestionario ISAAC (International Study of Asthma and Allergies in Childhood) a 5 460 niños de entre 6 a 8 y 11 a 14 años de edad, de nivel primaria, seleccionados de manera aleatoria. Se formaron seis grupos de alimentos a partir de un análisis de clusters jerárquico y se evaluó la relación con los padecimientos a través de modelos de regresión logística. RESULTADOS:El consumo de comida rápida tuvo un efecto adverso sobre la sibilancia actual (RM=1.82; IC95%=1.16-2.87) y el consumo de golosinas sobre más de tres episodios de sibilancia (RM=2.26; IC95%=1.04-4.95) y síntomas nasales sin gripa o catarro (RM=1.35; IC95%=1.06-1.71). CONCLUSIONES:Este estudio provee evidencia de que la dieta juega un papel muy importante, ya que el consumo abundante de comida rápida y golosinas incrementa el riesgo de asma y rinitis.

OBJECTIVE:To evaluate the relation between diet and the development of asthma and allergic rhinitis in schoolchildren from Cuernavaca, Morelos, Mexico. MATERIAL AND METHODS:We apply the ISAAC's questionnaire in 5460 schoolchildren from 6 to 8 and 11-14-year-old of elementary level selected in random form. Six groups of food were formed using a hierarchic clusters analysis and the association was evaluated using logistic regression models. RESULTS:The consumption of fast food had an adverse effect for current wheezing (OR=1.82; CI95%=1.16-2.87) and the consumption of tidbits for more than three episodes of wheezing (OR=2.26; CI95%=1.04-4.95) and nasal symptoms without cold, OR=1.35 (IC95%;1.06-1.71). CONCLUSIONS:This study provides evidence that the diet plays a very important role since the high consumption of fast food and tidbits increased the risk of asthma and rhinitis symptoms.

Efecto del ambiente rural sobre la prevalencia de rinitis alérgica en escolares de Mexicali, Baja California, México / The effects of a rural environment on the prevalence of allergic rhinitis among schoolchildren in Mexicali, Baja California, Mexico

OBJETIVOS: Determinar la prevalencia de síntomas de rinitis alérgica en escolares de Mexicali, Baja California, México, y evaluar la influencia del medio ambiente rural sobre esta afección. MÉTODOS: Estudio transversal poblacional mediante la aplicación de un cuestionario estandarizado en una muestra aleatoria de 2 087 escolares de 6 a 7 años (1 078 niñas y 1 009 niños) residentes en la ciudad de Mexicali, Baja California, México. Se evaluó la asociación entre variables de exposición y antecedentes clínicos personales y familiares, y dos variables dependientes: síntomas nasales y síntomas nasales y oculares, en ausencia de catarro o gripe, con sus razones de posibilidades (OR, odds ratios) e intervalos de confianza de 95 por ciento (IC95 por ciento). El estudio, realizado entre febrero y julio de 2004, utilizó la metodología del Estudio Internacional de Asma y Alergia en la Infancia (ISAAC). RESULTADOS: Las prevalencias generales de síntomas nasales y síntomas nasales y oculares fueron de 25,0 por ciento y 10,5 por ciento, respectivamente. Los niños y las niñas que habían vivido en el campo o zona rural en algún momento presentaron menor probabilidad de padecer síntomas nasales (OR = 0,43; IC95 por ciento: 0,24 a 0,77) y síntomas nasales y oculares (OR = 0,39; IC95 por ciento: 0,16 a 0,93), después de ajustar por factores de confusión. CONCLUSIONES: El contacto con el medio rural en los primeros años de vida disminuyó el riesgo de presentar rinitis alérgica en la población estudiada, independientemente de los antecedentes familiares de asma.

OBJECTIVES: To assess the prevalence of allergic rhinitis symptoms among schoolchildren in Mexicali, Baja California, Mexico, and determine what impact a rural environment might have on this condition. METHODS: A population-based, cross-sectional study using a standardized questionnaire administered to a random sample of 2 087 schoolchildren 6-7 years of age (1 078 girls and 1 009 boys) living in the city of Mexicali, Baja California, Mexico. The study analyzed associations between exposure variables and personal and family health history, and two dependent variables-nasal symptoms and nasal and ocular symptoms, in the absence of a cold or flu-using odd ratios (OR) and 95 percent Confidence Intervals (95 percentCI). The study took place in February-July 2004 and followed the methodology of the International Study of Asthma and Allergies in Childhood (ISAAC). RESULTS: The general prevalence of nasal symptoms and nasal and ocular symptoms was 25.0 percent and 10.5 percent, respectively. The boys and girls who had ever lived on a farm or in a rural area had a lower probability, adjusted for confounding variables, of presenting nasal symptoms (OR = 0.43; 95 percentCI: 0.24-0.77), or nasal and ocular symptoms (OR = 0.39; 95 percentCI: 0.16-0.93). CONCLUSIONS: In the study population, exposure to a rural environment in early childhood decreased the risk of developing allergic rhinitis, regardless of a family history of asthma.

Assessment of personal exposure to ozone in asthmatic children residing in Mexico City / Evaluación de la exposición personal a ozono en niños asmáticos de la Ciudad de México

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.

OBJETIVO: Realizamos este estudio para evaluar la exposición personal a ozono (O3p) en niños asmáticos de la Ciudad de México. MATERIAL Y MÉTODOS: Se incluyeron 158 niños entre diciembre de 1998 y abril de 2000. En promedio se obtuvieron tres mediciones por niño, utilizando filtros pasivos para medir O3p. Se caracterizaron los patrones de actividad y las concentraciones ambientales diarias de ozono (O3a) se obtuvieron de estaciones fijas cercanas a la residencia del niño. Los niveles promedio de O3a y las concentraciones ponderadas por el tiempo en diferentes microambientes (O3w) fueron usados como variables independientes para modelar las concentraciones de O3p, utilizando modelos de efectos mixtos. RESULTADOS: La media de O3p fue 7.8 ppb. Las principales variables en el modelo fueron: tiempo en exteriores, distancia, periodo de seguimiento y dos términos de interacción (R²=0.50, p<0.05). CONCLUSIONES: Las concentraciones de O3w pueden usarse como "proxi" de O3p, tomando en cuenta patrones de actividad y lugar de residencia.

Validez en el registro del pico espiratorio máximo de niños asmáticos de la Ciudad de México / Validity of peak flow record in asthmatic children residing in Mexico City

OBJETIVO: Determinar la concordancia entre el pico espiratorio forzado (PEF) registrado por padres de niños asmáticos y el PEF electrónico que es el almacenado en el AirWatch (PEFe). MATERIAL Y MÉTODOS: Se obtuvo el PEF de 42 niños de 5 a 15 años de edad del Hospital Infantil de México Federico Gómez de la Ciudad de México entre octubre de 1998 y 1999. Los padres registraron el valor máximo del PEF en un diario de salud. Se calculó la correlación de Spearman entre el PEFe y el PEFr. Utilizamos un modelo logístico de efectos mixtos. RESULTADOS: La correlación del PEFe y el PEFr fue r= 0.96 (p<0.05) en niños con diagnóstico de asma moderada o severa y r= 0.40 (p< 0.05) en niños con asma leve. El tiempo de seguimiento y severidad del asma, el género y edad del niño y sus interacciones eran predictores de las diferencias entre el PEFe y el PEFr. CONCLUSIONES: Los padres de niños de 6 a 8 años con asma moderada o severa reportan mejor el PEF en el diario de salud a lo largo del seguimiento que los padres de otros grupos.

OBJECTIVE: To determine the concordance between maximum peak expiratory flow records (PEFr) reported by the parents of asthmatic children and the electronic values stored by the AirWatch device (PEFe). MATERIAL AND METHODS: Records of PEF measurements between October 1998 and 1999 were obtained from 42 asthmatic children 5 to 15 years of age recruited at the Hospital Infantil de Mexico Federico Gomez, in Mexico City. Parents recorded the maximum value in the health diary. Spearman correlation was calculated between PEFe and PEFr and a mixed-effects logistic model was used. RESULTS: The correlation between PEFe and PEFr was r=0.96 (p<0.05) among children with a diagnosis of moderate or severe asthma and r=0.40 (p<0.05) among children diagnosed with mild asthma. Follow-up time, asthma severity, gender and age of the child and their interactions were predictors of the differences between PEFe and PEFr. CONCLUSIONS: Parents of children with moderate or severe asthma from 6 to 8 years of age report PEF values with greater accuracy during follow-up than others.

Breast-feeding practices in Mexico: results from the Second National Nutrition Survey 1999

OBJETIVO: Evaluar las prácticas de lactancia y las determinantes de la lactancia exclusiva (LE) hasta <4 y <6 m, en mujeres con hijos menores de 24 m de la segunda Encuesta Nacional de Nutrición 1999. MATERIAL Y MÉTODOS: Las prácticas de lactancia se estimaron del día y la noche anteriores a la entrevista. Los determinantes de LE<4m y LE<6m fueron analizados mediante regresión logística para muestras complejas. RESULTADOS: La prevalencia de LE<4m fue 25.7 por ciento, y <6 m 20.3 por ciento. La tasa de lactancia continuada (segundo año) 30.9 por ciento, mediana de duración de lactancia 9 m, y proporción de amamantados alguna vez 92.3 por ciento. La probabilidad (p)LE<4m estuvo determinada por edad, y el sexo del infante, por el nivel socioeconómico y etnicidad maternas, y por la interacción entre el sexo y el nivel socioeconómico. La p LE<6m estuvo determinada por edad y la longitud del infante y por el empleo, etnicidad y nivel socioeconómico de la madre. CONCLUSIONES: La duración y prevalencia de LE son bajas en México, poco mejores que hace 20 años. Las características del infante y de la madre determinan la p LME. Para promover la salud del niño, es urgente implementar programas agresivos de protección y promoción de la lactancia, así como evaluar y adecuar formalmente los existentes.

Antioxidant supplementation and lung functions among children with asthma exposed to high levels of air pollutants.

To evaluate whether acute effects of ozone, nitrogen dioxide, and particulates with mass median diameter less than 10 micro m could be attenuated by antioxidant vitamin supplementation, we conducted a randomized trial using a double-blinded design. Children with asthma (n = 158) who were residents of Mexico City were randomly given a daily supplement of vitamins (50 mg/day of vitamin E and 250 mg/day of vitamin C) or a placebo and were followed from October 1998 to April 2000. Pulmonary function tests were carried out twice a week in the morning. During the follow-up observation period, the mean 1-hour maximum ozone level was 102 ppb (SD = 47), and the mean 24-hour average PM(10) level was 56.7 micro g/m(3) (SD = 27.4). In children with moderate and severe asthma, ozone levels 1 day before spirometry were inversely associated significantly with forced expiratory flow (FEF(25-75)) (-13.32 ml/second/10 ppb; p = 0.000), FEV(1) (-4.59 ml/10 ppb; p = 0.036), and peak expiratory flow (PEF) (-15.01 ml/second/10 ppb; p = 0.04) in the placebo group after adjusting for potential confounding factors. No association between ozone and lung functions was observed in the supplement group. We observed significant differences in lung function decrements between groups for FEF(25-75) and PEF. Our results suggest that supplementation with antioxidants might modulate the impact of ozone exposure on the small airways of children with moderate to severe asthma.