Spirometric function in children of Mexico City compared to Mexican-American children

Differences in percentage predicted spirometric values obtained with thirteen reference equations applied to healthy children

BACKGROUND

There is limited information on the discrepancy between the spirometric values calculated with diverse spirometric prediction equations in normal children.

OBJECTIVE

To determine the differences in percentage predicted (PP) values calculated through thirteen prediction equations (PEs) in healthy Chilean children.

METHODS

We compared the PP values for FVC, FEV1, FEF25-75% and FEV1/FVC obtained by applying thirteen PEs, using GLI-2012 as a gold standard reference equation and including race neutral GLI-2022 in the analysis; PP values are from a group of 208 healthy Chilean children aged 7 to 17 years.

RESULTS

In boys, the range of differences for FVC between PEs compared to the reference group went from -5.47% to 20.82% and from -6.4% to 19.74% in girls. For FEV1, in girls, the range of differences went from -5.96% to 18.01% and from -5,04% to 20.67% in boys. Significant differences between GLI-2012 PPs and the other PEs were observed more frequently in girls than in boys (p < 0.001).

CONCLUSIONS

There is a wide difference between the spirometric PPs values by different PEs, including race neutral GLI-2022. Our findings, especially given the potential interpretative and clinical implications, might suggest the need for conducting standardized, multicenter studies in Latin America to determine which PEs would better fit pediatric populations in this region.

Maximal inspiratory and expiratory flow at moderate altitude: a study of a Latin American population

Background

Peak inspiratory and expiratory flows (PIF, PEF) are parameters used to evaluate the mechanics of the respiratory system. These parameters can vary based on whether they are measured using mechanical devices vs. spirometry and based on the barometric pressure at which the measurements are obtained. Our objectives were (1) to report the normal values and variability of PEF and PIF of a Latin American population living at a moderate altitude (2240 m above sea level), (2) to analyze the adjustment of reference values obtained at sea level with those obtained in healthy subjects living at a moderate altitude, and (3) to assess the correlation between PEF obtained by spirometry (PEFs) and PEF obtained by mechanical devices (PEFm).

Methods

In this prospective and transversal study, men and women with good respiratory health aged between 2.8 and 68 years old were invited to participate. Randomly, they underwent spirometry (to measure PEFs and PIFs) and mechanical flowmetry (to measure PEFm).

Results

A total of 314 subjects participated, with an average age of 24.3 ± 16.4 years; 59% were Women. The main determinants for the reference equations were age, weight, height and sex at birth. The agreement of the PEFm, PEFs and PIFs values was inconsistent with that reported by other authors, even at the same barometric pressure. The association between PEFm and PEFs was r = 0.91 (p < 0.001), and the correlation coefficient of concordance was 0.84.

Conclusions

The PEFm, PEFs, and PIFs measurements in individuals living at moderate altitudes are different from those found by other authors in cities with different barometric pressures and ethnicities.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01943-x.

Comparing Spirometric Reference Values From Childhood to Old Age Estimated by LMS and Linear Regression Models

BACKGROUND

Proper reference values for lung function testing are essential for achieving adequate interpretations. The LMS procedure (lambda, mu, sigma) permits continuous analyses of entire populations avoiding gaps in the transition between childhood and adulthood. It also allows more precise calculations of average values, dispersion, and 5th percentiles, which are usually considered the lower limit of normality. The objective of this study was to compare our results fitted with the LMS method with standard multiple linear regression, and with those from international Global Lung Function Initiative (GLI) equations.

METHODS

Data from 9835 healthy residents of the metropolitan area of Mexico City aged 8-80 years were compiled from several studies: EMPECE, PLATINO, adult Mexican workers and two unpublished studies. The LMS procedure and multiple linear regression models were fit to obtain reference equations using R software.

RESULTS

Residuals from the LMS models had a median closer to zero, and smaller dispersion than those from the linear model, but differences although statistically significant were very small and of questionable practical relevance. For example, for females and ln(FEV₁), median residual was -0.001 with p25 of -0.08 and p75 of 0.08 for LMS, compared with 0.004 (-0.08, 0.09) [p<0.05] for the linear model. Average spirometric values for a given height for our population, were higher than those predicted by the GLI study.

CONCLUSION

Continuous reference equations for the Mexican population calculated using the LMS technique showed slightly better fit than linear regression models.

Bronchodilator Response in FVC Is Larger and More Relevant Than in FEV1 in Severe Airflow Obstruction

BACKGROUND

Recommendations on interpreting tests of bronchodilator responsiveness (BDR) are conflicting. We investigated the dependence of BDR criteria on sex, age, height, ethnicity, and severity of respiratory impairment.

METHODS

BDR test data were available from clinical patients in the Netherlands, New Zealand, and the United States (n = 15,278; female subjects, 51.7%) and from surveys in Canada, Norway, and five Latin-American countries (n = 16,250; female subjects, 54.7%). BDR calculated according to FEV₁, FVC, and FEV₁/FVC was expressed as absolute change, a percentage of the baseline level (% baseline), a percentage of the predicted value (% predicted), and z score.

RESULTS

Change (Δ) in FEV₁ and FVC, in milliliters, was unrelated to the baseline value but was biased toward age, height, sex, and level of airways obstruction; ΔFEV₁ was significantly lower in African Americans. In 1,106 subjects with low FEV₁ (200-1,621 mL) the FEV₁ increased by 12% to 44.7% relative to baseline but < 200 mL. Expressing BDR as a percentage of the predicted value or as a z score attenuated the bias and made the 200-mL criterion redundant, but reduced positive responses by half. ΔFEV₁ % baseline increased with the level of airflow obstruction but decreased with severe obstruction when expressed as z scores or % predicted; ΔFVC, however expressed, increased with the level of airflow obstruction.

CONCLUSIONS

Expressing FEV₁ responsiveness as % baseline spuriously suggests that responsiveness increases with the severity of respiratory impairment. Expressing change in FEV₁ or FVC as % predicted or as z scores eliminates this artifact and renders the required 200-mL minimum increase redundant. In severe airways obstruction ΔFVC should be critically evaluated as an index of clinically important relief of hyperinflation, with implications for bronchodilator drug trials.

Socioeconomic Status and Longitudinal Lung Function of Healthy Mexican Children

Introduction

Our aim was to estimate the longitudinal effect of Socioeconomic status (SES) on lung function growth of Mexican children and adolescents.

Materials and Methods

A cohort of Mexican children in third grade of primary school was followed with spirometry twice a year for 6 years through secondary school. Multilevel mixed-effects lineal models were fitted for the spirometric variables of 2,641 respiratory-healthy Mexican children. Monthly family income (in 2002 U.S. dollars [USD]) and parents’ years completed at school were used as proxies of SES.

Results

Individuals with higher SES tended to have greater height for age, and smaller sitting height/standing height and crude lung function. For each 1-year increase of parents’ schooling, Forced expiratory volume in 1 sec (FEV₁) and Forced vital capacity (FVC) increased 8.5 (0.4%) and 10.6 mL (0.4%), respectively (p <0.05) when models were adjusted for gender. Impact of education on lung function was reduced drastically or abolished on adjusting by anthropometric variables and ozone.

Conclusions

Higher parental schooling and higher monthly family income were associated with higher lung function in healthy Mexican children, with the majority of the effect likely due to the increase in height-for-age.

Comparison between reference values for FVC, FEV1, and FEV1/FVC ratio in White adults in Brazil and those suggested by the Global Lung Function Initiative 2012

OBJECTIVE:

To evaluate the spirometry values predicted by the 2012 Global Lung Function Initiative (GLI) equations, which are recommended for international use, in comparison with those obtained for a sample of White adults used for the establishment of reference equations for spirometry in Brazil.

METHODS:

The sample comprised 270 and 373 healthy males and females, respectively. The mean differences between the values found in this sample and the predicted values calculated from the GLI equations for FVC, FEV₁, and VEF₁/FVC, as well as their lower limits, were compared by paired t-test. The predicted values by each pair of equations were compared in various combinations of age and height.

RESULTS:

For the males in our study sample, the values obtained for all of the variables studied were significantly higher than those predicted by the GLI equations (p < 0.01 for all). These differences become more evident in subjects who were shorter in stature and older. For the females in our study sample, only the lower limit of the FEV₁/FVC ratio was significantly higher than that predicted by the GLI equation.

CONCLUSIONS:

The predicted values suggested by the GLI equations for White adults were significantly lower than those used as reference values for males in Brazil. For both genders, the lower limit of the FEV₁/FVC ratio is significantly lower than that predicted by the GLI equations.

Predictive models and spatial variations of vital capacity in healthy people from 6 to 84 years old in China based on geographical factors

The aim of this study was to provide a scientific basic for a unified standard of the reference value of vital capacity (VC) of healthy subjects from 6 and 84 years old in China. The normal reference value of VC was correlated to seven geographical factors, including altitude (X1), annual duration of sunshine (X2), annual mean air temperature (X3), annual mean relative humidity (X4), annual precipitation amount (X5), annual air temperature range (X6) and annual mean wind speed (X7). Predictive models were established by five different linear and nonlinear methods. The best models were selected by t-test. The geographical distribution map of VC in different age groups can be interpolated by Kriging's method using ArcGIS software. It was found that the correlation of VC and geographical factors in China was quite significant, especially for both males and females aged from 6 to 45. The best models were built for different age groups. The geographical distribution map shows the spatial variations of VC in China precisely. The VC of healthy subjects can be simulated by the best model or acquired from the geographical distribution map provided the geographical factors for that city or county of China are known.

Spirometric reference values in urban children in Madagascar: poverty is a risk factor for low lung function

BACKGROUND

Studies about children with respiratory diseases in Africa are impeded by the dearth of reliable data for the vast majority of countries on the continent. This study was conducted to establish representative reference values, therefore allowing a more accurate evaluation of lung function in Malagasy children.

METHODS

One thousand two hundred thirty-six students from three public and five private schools aged 8-12 years were recruited. A total of 1,093 children were healthy, had a valid lung function measurement and were thus deemed evaluable for this study. Lung function data were collected on consecutive days in Antananarivo, Madagascar's capital, using spirometry and a modified International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire.

RESULTS

The lung volumes found were substantially lower compared to Caucasian and African equations. The mean Z-score (Stanojevic) for the forced vital capacity (FVC) found was -1.45 and -0.93 for the forced expiratory volume in 1 sec (FEV1) with significant differences between private and public schools (FVC: P = 0.0023, FEV1: P = 0.0004).

CONCLUSIONS

The equations established for school children in Madagascar's capital Antananarivo showed lung function values were lower than reference values for the same age group seen not only in European, but also in African American and African children. The unique ethnicity of the Malagasy people, which combines Southeast-Asian with substantial African influences, the heavy burden of pollution and poverty may explain these differences.

Longitudinal lung function growth of Mexican children compared with international studies

Introduction

Our aim was to compare the longitudinal lung function growth of Mexican children and adolescents with the collated spirometric reference proposed for international use and with that of Mexican-Americans from the National Health State Examination Survey III (NHANES) III study.

Materials and Methods

A cohort of Mexican children in third year of primary school was followed with spirometry twice a year through secondary school. Multilevel mixed-effects lineal models separated by gender were fit for the spirometric variables of 2,641 respiratory-healthy Mexican children expressed as Z-scores of tested reference equations. Impact of adjustment by sitting height on differences with Mexican-American children was observed in a subsample of 1,987 children.

Results

At same gender, age, and height, Mexican children had increasingly higher forced expiratory volume in 1 s (FEV₁) and Forced vital capacity (FVC) than the children from the collated reference study (mean Z-score, 0.68 for FEV₁ and 0.51 for FVC) and than Mexican-American children (Z-score, 0.23 for FEV₁ and 0.21 for FVC) respectively. Differences with Mexican-Americans were not reduced by adjusting by sitting height.

Conclusions

For reasons that remain unclear, the gender-, age-, and height-adjusted lung function of children from Mexico City is higher than that reported by several international studies.

Multi-ethnic reference values for spirometry for the 3-95-yr age range: the global lung function 2012 equations

The aim of the Task Force was to derive continuous prediction equations and their lower limits of normal for spirometric indices, which are applicable globally. Over 160,000 data points from 72 centres in 33 countries were shared with the European Respiratory Society Global Lung Function Initiative. Eliminating data that could not be used (mostly missing ethnic group, some outliers) left 97,759 records of healthy nonsmokers (55.3% females) aged 2.5-95 yrs. Lung function data were collated and prediction equations derived using the LMS method, which allows simultaneous modelling of the mean (mu), the coefficient of variation (sigma) and skewness (lambda) of a distribution family. After discarding 23,572 records, mostly because they could not be combined with other ethnic or geographic groups, reference equations were derived for healthy individuals aged 3-95 yrs for Caucasians (n=57,395), African-Americans (n=3,545), and North (n=4,992) and South East Asians (n=8,255). Forced expiratory value in 1 s (FEV(1)) and forced vital capacity (FVC) between ethnic groups differed proportionally from that in Caucasians, such that FEV(1)/FVC remained virtually independent of ethnic group. For individuals not represented by these four groups, or of mixed ethnic origins, a composite equation taken as the average of the above equations is provided to facilitate interpretation until a more appropriate solution is developed. Spirometric prediction equations for the 3-95-age range are now available that include appropriate age-dependent lower limits of normal. They can be applied globally to different ethnic groups. Additional data from the Indian subcontinent and Arabic, Polynesian and Latin American countries, as well as Africa will further improve these equations in the future.

Pulmonary function in children and adolescents with postinfectious bronchiolitis obliterans

OBJECTIVE

To describe the pulmonary function in children and adolescents with postinfectious bronchiolitis obliterans (PIBO), as well as to evaluate potential risk factors for severe impairment of pulmonary function.

METHODS

The pulmonary function of 77 participants, aged 8-18 years, was assessed by spirometry and plethysmography. The following parameters were analyzed: FVC; FEV1; FEF25-75%; FEV1/FVC; RV; TLC; RV/TLC; intrathoracic gas volume; and specific airway resistance (sRaw). We used Poisson regression to investigate the following potential risk factors for severe impairment of pulmonary function: gender; age at first wheeze; age at diagnosis; family history of asthma; tobacco smoke exposure; length of hospital stay; and duration of mechanical ventilation.

RESULTS

The mean age was 13.5 years. There were pronounced decreases in FEV1 and FEF25-75%, as well as increases in RV and sRaw. These alterations are characteristic of obstructive airway disease. For the parameters that were the most affected, the mean values (percentage of predicted) were as follows: FEV1 = 45.9%; FEF25-75% = 21.5%; RV = 281.1%; RV/TLC = 236.2%; and sRaw = 665.3%. None of the potential risk factors studied showed a significant association with severely impaired pulmonary function.

CONCLUSIONS

The patients with PIBO had a common pattern of severe pulmonary function impairment, characterized by marked airway obstruction and pronounced increases in RV and sRaw. The combination of spirometric and plethysmographic measurements can be more useful for assessing functional damage, as well as in the follow-up of these patients, than are either of these techniques used in isolation. Known risk factors for respiratory diseases do not seem to be associated with severely impaired pulmonary function in PIBO.

The effect of moderate altitude on some respiratory parameters of physical education and sports' students

OBJECTIVES

Analysis of the effects of moderate altitude on some respiratory functions of students enrolled in School of Physical Education and Sports.

METHODS

The study group comprised of 9 female and 10 male volunteers who were attending a 5-day skiing training camp. All participants were enrolled in School of Physical Education and Sports at Gazi University. The male students had an age range of 22.2 +/- 1.7 years, height of 175.0 +/- 4.3 cm, and body weight of 71.0 +/- 10.4 kg; the female students had an age range of 21.2 +/- 1.7 years, height of 167.1 +/- 4.9 cm, and body weight of 53.7 +/- 4.8 kg. Respiratory tests were performed on the 1st and 5th days (the first and second measurements) at an altitude of 1880 m (in Ilgaz Mountain); 10 days after being exposed to high altitude, further tests were performed at an altitude of 856 m (in Ankara) (the third measurement). Data were analyzed using SPSS software (version 10.0). Intragroup differences were analyzed using repeated measures analysis of variance (ANOVA). According to the results of normality test results, an independent-sample t test was used in comparisons between the groups. A significance level of p < .05 was used in analysis.

RESULTS

Statistical analysis indicated that there was no significant difference between the intragroup comparisons of female and male students. Intergroup comparisons showed significant differences in forced vital capacity (FVC), forced expiratory volume (FEV), peak expiratory flow (PEF), maximal voluntary ventilation (MVV), and VC parameters (p < .05).

CONCLUSION

The authors conclude that moderate altitude does not have any effect on some respiratory parameters after 5 days of skiing camp.

Spirometric reference equations for healthy children aged 6 to 11 years in Taiwan

BACKGROUND

Spirometry is a valuable technique for evaluating pulmonary function, but there were few normative reference values for young children in Taiwan, and none for the last 10 years. The objective of our study was to establish updated reference values and equations for children aged 6-11 years in northern Taiwan.

METHODS

A total of 309 healthy children (153 boys and 156 girls) were enrolled in the present study. The data of at least 3 trials for each child were collected, and the highest values analyzed. The analyzed pulmonary function parameters were focused on forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), peak expiratory flow rate (PEF), forced expiratory flow between 25% and 75% expired volume (FEF25-75), and the ratio of FEV1/FVC.

RESULTS

The results revealed that there were mostly no significant differences between boys and girls, and the standing height (H, cm) was the factor with the highest correlation with the pulmonary function parameters. Regression equations of the major pulmonary function parameters for both boys and girls were obtained: FVC = -2.690 + 0.0330H; FEV1 = -2.559 + 0.0311H; PEF = -300.231 + 3.938H; FEF25-75 = -3.218 + 0.0425H (p < 0.001).

CONCLUSION

Our study determined the updated normative values and reference equations for Chinese children aged 6-11 years living in northern Taiwan. These values can be used as normative reference values to evaluate pulmonary function in diseased children with the same ethnicity and lifestyle.

Evaluation of candidate genes in a genome-wide association study of childhood asthma in Mexicans

BACKGROUND

More than 200 asthma candidate genes have been examined in human association studies or identified with knockout mouse approaches. However, many have not been systematically replicated in human populations, especially those containing a large number of tagging single nucleotide polymorphisms (SNPs).

OBJECTIVE

We comprehensively evaluated the association of previously implicated asthma candidate genes with childhood asthma in a Mexico City population.

METHODS

From the literature, we identified candidate genes with at least 1 positive report of association with asthma phenotypes in human subjects or implicated in asthma pathogenesis using knockout mouse experiments. We performed a genome-wide association study in 492 asthmatic children aged 5 to 17 years and both parents using the Illumina HumanHap 550v3 BeadChip. Separate candidate gene analyses were performed for 2933 autosomal SNPs in the 237 selected genes by using the log-linear method with a log-additive risk model.

RESULTS

Sixty-one of the 237 genes had at least 1 SNP with a P value of less than .05 for association with asthma. The 9 most significant results were observed for rs2241715 in the gene encoding TGF-beta1 (TGFB1; P = 3.3 x 10(-5)), rs13431828 and rs1041973 in the gene encoding IL-1 receptor-like 1 (IL1RL1; P = 2 x 10(-4) and 3.5 x 10(-4)), 5 SNPs in the gene encoding dipeptidyl-peptidase 10 (DPP10; P = 1.6 x 10(-4) to 4.5 x 10(-4)), and rs17599222 in the gene encoding cytoplasmic FMR1 interacting protein 2 (CYFIP2; P = 4.1 x 10(-4)). False discovery rates were less than 0.1 for all 9 SNPs. Multimarker analysis identified TGFB1, IL1RL1, the gene encoding IL-18 receptor 1 (IL18R1), and DPP10 as the genes most significantly associated with asthma.

CONCLUSIONS

This comprehensive analysis of literature-based candidate genes suggests that SNPs in several candidate genes, including TGFB1, IL1RL1, IL18R1, and DPP10, might contribute to childhood asthma susceptibility in a Mexican population.

Genome-wide association study implicates chromosome 9q21.31 as a susceptibility locus for asthma in mexican children

Many candidate genes have been studied for asthma, but replication has varied. Novel candidate genes have been identified for various complex diseases using genome-wide association studies (GWASs). We conducted a GWAS in 492 Mexican children with asthma, predominantly atopic by skin prick test, and their parents using the Illumina HumanHap 550 K BeadChip to identify novel genetic variation for childhood asthma. The 520,767 autosomal single nucleotide polymorphisms (SNPs) passing quality control were tested for association with childhood asthma using log-linear regression with a log-additive risk model. Eleven of the most significantly associated GWAS SNPs were tested for replication in an independent study of 177 Mexican case-parent trios with childhood-onset asthma and atopy using log-linear analysis. The chromosome 9q21.31 SNP rs2378383 (p = 7.10x10(-6) in the GWAS), located upstream of transducin-like enhancer of split 4 (TLE4), gave a p-value of 0.03 and the same direction and magnitude of association in the replication study (combined p = 6.79x10(-7)). Ancestry analysis on chromosome 9q supported an inverse association between the rs2378383 minor allele (G) and childhood asthma. This work identifies chromosome 9q21.31 as a novel susceptibility locus for childhood asthma in Mexicans. Further, analysis of genome-wide expression data in 51 human tissues from the Novartis Research Foundation showed that median GWAS significance levels for SNPs in genes expressed in the lung differed most significantly from genes not expressed in the lung when compared to 50 other tissues, supporting the biological plausibility of our overall GWAS findings and the multigenic etiology of childhood asthma.

Spirometry

Pulmonary function testing is useful for the diagnosis and management of a variety of pulmonary conditions, and the most commonly obtained component is spirometry. Spirometry is most useful in the evaluation of obstructive airway disorders but can be a helpful tool in the management of patients with chest restriction or mixed disease. The utility of spirometry depends on reproducibility, standardization, and quality of testing. Accurate interpretation of test results depends on the availability of reference equations applicable to the subject undergoing testing. This paper reviews basic concepts, testing procedures, and interpretation of a single set of spirometry results as well as results obtained over time and gives an overview of previously published reference equations.

Genetic variation in ORM1-like 3 (ORMDL3) and gasdermin-like (GSDML) and childhood asthma

BACKGROUND

A genome-wide association study identified ORM1-like 3 (orosomucoid 1-like 3, ORMDL3) as an asthma candidate gene. Single nucleotide polymorphisms (SNPs) in the region including ORMDL3 on chromosome 17q21 were related to childhood asthma risk and ORMDL3 expression levels in Europeans.

OBJECTIVE

We examined whether polymorphisms in ORMDL3 and the adjacent gasdermin-like (GSDML) gene associated with asthma in the genome-wide association study are related to childhood asthma and atopy in a Mexico City population.

METHODS

We genotyped rs4378650 in ORMDL3 and rs7216389 in GSDML in 615 nuclear families consisting of asthmatic children aged 4-17 years and their parents. Atopy was determined by skin prick tests to 25 aeroallergens.

RESULTS

Individuals carrying the C allele of rs4378650 or the T allele of rs7216389 had increased risk of asthma [relative risk (RR) = 1.73, 95% confidence interval (CI) 1.19-2.53, P = 0.003 for one or two copies of rs4378650 C, and RR = 1.64, 95% CI 1.12-2.38, P = 0.009 for one or two copies of rs7216389 T). Linkage disequilibrium between the two SNPs was high (r(2) = 0.92). Neither of the SNPs was associated with the degree of atopy. A meta-analysis of five published studies on rs7216389 in nine populations gave an odds ratio for asthma of 1.44 (95% CI, 1.35-1.54, P < 0.00001).

CONCLUSIONS

Our results and the meta-analysis provide evidence to confirm the finding from a recent genome-wide association study that polymorphisms in ORMDL3 and the adjacent GSDML may contribute to childhood asthma.

Lack of association between genetic variation in G-protein-coupled receptor for asthma susceptibility and childhood asthma and atopy

G-protein-coupled receptor for asthma susceptibility (GPRA or GPR154) was identified as an asthma and atopy candidate gene by positional cloning. Some subsequent studies suggest associations of GPRA single nucleotide polymorphisms (SNPs) and haplotypes with asthma or atopy susceptibility. However, the associated SNPs or haplotypes vary among studies. The role of GPRA genetic variation in asthma and atopy remains unsolved. Published data on GRPA variants and asthma come exclusively from Caucasian and Asian populations. We examined whether GPRA SNPs and haplotypes are associated with asthma and atopy in a Mexican population. We genotyped and analyzed 27 GPRA SNPs in 589 nuclear families consisting of asthmatic children aged 4-17 years of age and their parents in Mexico City. Atopy was determined by skin prick tests to 25 aeroallergens. The 27 SNPs examined provided excellent coverage of the GPRA gene. GPRA SNPs and haplotypes were not associated with childhood asthma and the degree of atopy to aeroallergens in a Mexican population. Our review of studies of GPRA variants in relation to asthma phenotypes shows considerable heterogeneity. Accordingly, our results suggest that GPRA variants are not an important contributor to childhood asthma and atopy susceptibility in a Mexican population.

Exhaled breath malondialdehyde as a marker of effect of exposure to air pollution in children with asthma

BACKGROUND

Assessment of the adverse effects of oxidative stress related to air pollution is limited by the lack of biological markers of dose to the lungs.

OBJECTIVE

We evaluated the use of exhaled breath condensate (EBC) malondialdehyde as a biomarker of exposure to traffic-related pollution in children with asthma as part of a panel study in Mexico City.

METHODS

Standard spirometry and collection of EBC and nasal lavage were performed. Environmental monitoring sites were located within 5 km of the children's homes and schools. Data were analyzed by using generalized estimating equations.

RESULTS

A total of 480 samples of malondialdehyde were obtained from 107 patients with asthma, with a median level of 18.7 (interquartile range [IQR], 12.4-28.7) nmol. Ambient particulates less than 2.5 microg/m(3) and ozone levels on the day of sampling were significantly associated with higher malondialdehyde levels. A 14.2-microg/m(3) (IQR) increase in 8-hour moving average particulates less than 2.5 microg/m(3) in size was associated with a 1.12-nmol increase in malondialdehyde and a 15.9-ppb (IQR) increase in 8-hour moving average ozone with a 1.16-nmol increase in malondialdehyde. Malondialdehyde levels were inversely associated with forced vital capacity and FEV(1) and positively associated with IL-8 levels in nasal lavage.

CONCLUSION

Exhaled breath condensate malondialdehyde was related to both air pollution exposure and changes in lung function and inflammatory markers.

[Respiratory dynamics measurements in children with four to ten years of age]

BACKGROUND

respiratory dynamics measurements are frequently used in the speech-language pathology practice, but few are the scientific data for children.

AIM

to study the respiratory dynamics in children with nasal breathing.

METHOD

the study was performed with a stratified random sample of 106 nasal breathing children, male and female, from schools of the city of Marília-SP, with ages between four and ten years. The following measurements were obtained: vital capacity (VC) in both standing and sitting positions, with and without nasal occlusion; maximum phonation time (MPT) of sustained vowels and consonants and also of speech when counting numbers.

RESULTS

the mean values for VC in the standing position with and without nasal occlusion were of 1515.56ml and 1538.67ml respectively and for the sitting position of 1524ml and 1539.15ml respectively. MPT of vowels in seconds were: /a/ = 8.32, /i/ = 8.61 and /ul = 8.42; of consonants: /s/ = 6.64 and /z/ = 7.65; and when counting numbers: 7.76. It was observed that the mean values of these measurements progressively increased according to age. There was a statistically significant difference (p<0.05) not only for the MPT of vowels but also for the MPT of consonants in older children, i.e. between 4 and 10 year olds, 4 and 9 year olds and 4 and 8 year olds. There was no significant statistical difference for the VC values in consecutive age groups. There was a strong association between VC and the child's physical development.

CONCLUSION

this study presented respiratory dynamics measurements in children that can be used for the spech-language diagnosis and therapy. Other studies should be developed in order to bring additional information on the subject.

Genetic variation in S-nitrosoglutathione reductase (GSNOR) and childhood asthma

BACKGROUND

S-nitrosothiols are potent endogenous bronchodilators depleted in asthmatic airway lining fluid. S-nitrosoglutathione reductase (GSNOR; also known as alcohol dehydrogenase 5 or formaldehyde dehydrogenase) catalyzes the metabolism of S-nitrosoglutathione (GSNO) and controls intracellular levels of S-nitrosothiols. GSNOR knockout mice have increased lung S-nitrosothiol levels and are therefore protected from airway hyperresponsiveness after methacholine or allergen challenge.

OBJECTIVE

We sought to investigate whether genetic variation in GSNOR is associated with childhood asthma and atopy.

METHODS

We genotyped 5 tagging and 2 additional single nucleotide polymorphisms (SNPs) in GSNOR in 532 nuclear families consisting of asthmatic children aged 4 to 17 years and both parents in Mexico City. Atopy was determined by means of skin prick testing.

RESULTS

Carrying 1 or 2 copies of the minor allele of SNP rs1,154,404 was associated with decreased risk of asthma (relative risk [RR], 0.77; 95% CI, 0.61-0.97; P = .028 for 1 copy and RR, 0.66; 95% CI, 0.44-0.99; P = .046 for 2 copies). Homozygosity for the minor allele of SNP rs28,730,619 was associated with increased risk of asthma (RR, 1.60; 95% CI, 1.13-2.26; P = .0077). Haplotype analyses supported the single SNP findings. GSNOR SNPs were not associated with the degree of atopy.

CONCLUSION

This is the first study of genetic polymorphisms in GSNOR and asthma. These data suggest that genetic variation in GSNOR might play a role in asthma susceptibility.

CLINICAL IMPLICATIONS

The association of GSNOR polymorphisms with asthma suggests a potential therapeutic target.

Lung function growth in children with long-term exposure to air pollutants in Mexico City

RATIONALE

Although short-term exposure to air pollution has been associated with acute, reversible lung function decrements, the impact of long-term exposure has not been well established.

OBJECTIVES

To evaluate the association between long-term exposure to ozone (O(3)), particulate matter less than 10 mum in diameter (PM(10)), and nitrogen dioxide (NO(2)) and lung function growth in Mexico City schoolchildren.

METHODS

A dynamic cohort of 3,170 children aged 8 years at baseline was followed from April 23, 1996, through May 19, 1999. The children attended 39 randomly selected elementary schools located near 10 air quality monitoring stations and were visited every 6 months. Statistical analyses were performed using general linear mixed models.

MEASUREMENTS AND MAIN RESULTS

After adjusting for acute exposure and other potential confounding factors, deficits in FVC and FEV(1) growth over the 3-year follow-up period were significantly associated with exposure to O(3), PM(10), and NO(2). In multipollutant models, an interquartile range (IQR) increase in mean O(3) concentration (IQR, 11.3 ppb) was associated with an annual deficit in FEV(1) of 12 ml in girls and 4 ml in boys, an IQR range (IQR, 36.4 microg/m(3)) increase in PM(10) with an annual deficit in FEV(1) of 11 ml in girls and 15 ml in boys, and an IQR range (IQR, 12.0 ppb) increase in NO(2) with an annual deficit in FEV(1) of 30 ml in girls and 25 ml in boys.

CONCLUSIONS

We conclude that long-term exposure to O(3), PM(10), and NO(2) is associated with a deficit in FVC and FEV(1) growth among schoolchildren living in Mexico City.

Parental smoking modifies the relation between genetic variation in tumor necrosis factor-alpha (TNF) and childhood asthma

BACKGROUND

Polymorphisms in the proinflammatory cytokine genes tumor necrosis factor-alpha (TNF) and lymphotoxin-alpha (LTA, also called TNF-beta) have been associated with asthma and atopy in some studies. Parental smoking is a consistent risk factor for childhood asthma. Secondhand smoke and ozone both stimulate TNF production.

OBJECTIVES

Our goal was to investigate whether genetic variation in TNF and LTA is associated with asthma and atopy and whether the association is modified by parental smoking in a Mexican population with high ozone exposure.

METHODS

We genotyped six tagging single nucleotide polymorphisms (SNPs) in TNF and LTA, including functional variants, in 596 nuclear families consisting of asthmatics 4-17 years of age and their parents in Mexico City. Atopy was determined by skin prick tests.

RESULTS

The A allele of the TNF-308 SNP was associated with increased risk of asthma [relative risk (RR) = 1.54; 95% confidence interval (CI), 1.04-2.28], especially among children of non-smoking parents (RR = 2.06; 95% CI, 1.19-3.55; p for interaction = 0.09). Similarly, the A allele of the TNF-238 SNP was associated with increased asthma risk among children of nonsmoking parents (RR = 2.21; 95% CI, 1.14-4.30; p for interaction = 0.01). LTA SNPs were not associated with asthma. Haplotype analyses reflected the single SNP findings in magnitude and direction. TNF and LTA SNPs were not associated with the degree of atopy.

CONCLUSIONS

Our results suggest that genetic variation in TNF may contribute to childhood asthma and that associations may be modified by parental smoking.

Genetic polymorphisms in transforming growth factor beta-1 (TGFB1) and childhood asthma and atopy

Transforming growth factor beta-1 (TGFB1) may influence asthma by modulating allergic airway inflammation and airway remodeling. The role of single nucleotide polymorphisms (SNPs) of TGFB1 in asthma remains inconclusive. We examined TGFB1 SNPs in relation to asthma risk and degree of atopy among 546 case-parent triads, consisting of asthmatics aged 4-17 years and their parents in Mexico City. Atopy to 24 aeroallergens was determined by skin prick tests. We genotyped five TGFB1 SNPs, including two known functional SNPs [C-509T (rs1800469), T869C (rs1982073)] and three others (rs7258445, rs1800472, rs8179181), using TaqMan and Masscode assays. We analyzed the data using log-linear and polytomous logistic methods. Three associated SNPs, including the two known functional SNPs, were statistically significantly related to asthma risk. Individuals carrying the T allele of C-509T had an increased risk of asthma [relative risk (RR)=1.42, 95% confidence interval (CI)=1.08-1.87 for one copy; RR (95%CI)=1.95 (1.36-2.78) for two copies]. For T869C, the RRs (95%CI) were 1.47 (1.09-1.98) for one and 2.00 (1.38-2.90) for two copies of the C allele. Similar results were found for rs7258445. The haplotype containing all three risk alleles conferred an increased risk of asthma (RR=1.48, 95% CI=1.11-1.95 for one copy; RR=1.77, 95% CI=1.22-2.57 for two copies). These three SNPs were also related to the degree of atopy. This largest study to date of genetic variation in TGFB1 and asthma and atopy adds to increasing evidence for a role in these disorders.

Obesity among children residing in Mexico City and its impact on lung function: a comparison with Mexican-Americans

BACKGROUND

The objective of the study was to describe the prevalence of obesity among Mexican children and its impact on ventilatory lung function.

METHODS

We studied cross-sectionally 6784 students between 8 and 20 years of age attending schools located <2 km away from ten air pollution monitors located throughout metropolitan Mexico City. The comparison group was made up of 1924 Mexican-Americans of the same age, studied during the NHANES-III examination, which included information on spirometry and body mass index (BMI).

RESULTS

Of all our subjects, 9.7% had a BMI >95(th) percentile of CDC growth charts (compared to 15.1% in Mexican-Americans) and 6.6% fulfilled the obesity criteria of the International Obesity Task Force (vs. 12.2%). Obesity was related to male gender, asthma and passive smoking. At the same height and gender, lung function was higher in Mexicans than in Mexican-Americans, perhaps due to altitude. In children 8-11 years of age, lung function increased in heavier subjects but, in older children and youths, function reached a plateau and decreased among children with highest BMI (inverted U pattern, seen in adults).

CONCLUSIONS

Obesity is higher in Mexican-American children and youths than in Mexicans. Spirometric function is affected adversely by obesity, especially in young people.

Genetic polymorphisms in arginase I and II and childhood asthma and atopy

BACKGROUND

A recent microarray study implicated arginase I (ARG1) and arginase II (ARG2) in mouse allergic asthma models and human asthma.

OBJECTIVES

To examine the association between genetic variation in ARG1 and ARG2 and childhood asthma and atopy risk.

METHODS

We enrolled 433 case-parent triads, consisting of patients with asthma 4 to 17 years old and their biologic parents, from the allergy clinic of a public hospital in Mexico City between 1998 and 2003. Atopy to 24 aeroallergens was determined by skin prick tests. We genotyped 4 single nucleotide polymorphisms (SNPs) of ARG1 and 4 SNPs of ARG2 with minor allele frequencies higher than 10% by using the TaqMan assay (Roche Molecular Systems, Pleasanton, Calif).

RESULTS

ARG1 SNPs and haplotypes were not associated with asthma, but all 4 ARG1 SNPs were associated with the number of positive skin tests (P = .007-.018). Carrying 2 copies of minor alleles for either of 2 highly associated ARG2 SNPs was associated with a statistically significant increased relative risk (RR) of asthma (1.5, 95% CI = 1.1-2.1 for arg2s1; RR = 1.6, 95% CI = 1.1-2.3 for arg2s2). The association was slightly stronger among children with a smoking parent (arg2s1 RR = 2.1, 95% CI = 1.2 - 3.9 with a smoking parent; RR = 1.2, 95% CI = 0.8-1.9 without; interaction P = .025). Haplotype analyses reduced the sample size but supported the single SNP results. One ARG2 SNP was related to the number of positive skin tests (P = .027).

CONCLUSION

Variation in arginase genes may contribute to asthma and atopy in children.

Chronic obstructive pulmonary disease in five Latin American cities (the PLATINO study): a prevalence study

BACKGROUND

Both the prevalence and mortality attributable to chronic obstructive pulmonary disease (COPD) seem to be increasing in low-income and middle-income countries, but few data are available. The aim of the PLATINO study, launched in 2002, was to describe the epidemiology of COPD in five major Latin American cities: São Paulo (Brazil), Santiago (Chile), Mexico City (Mexico), Montevideo (Uruguay), and Caracas (Venezuela).

METHODS

A two-stage sampling strategy was used in the five areas to obtain probability samples of adults aged 40 years or older. These individuals were invited to answer a questionnaire and undergo anthropometry, followed by prebronchodilator and postbronchodilator spirometry. We defined COPD as a ratio less than 0.7 of postbronchodilator forced expiratory volume in the first second over forced vital capacity.

FINDINGS

Complete information, including spirometry, was obtained from 963 people in São Paulo, 1173 in Santiago, 1000 in Mexico City, 885 in Montevideo, and 1294 in Caracas. Crude rates of COPD ranged from 7.8% (78 of 1000; 95% CI 5.9-9.7) in Mexico City to 19.7% (174 of 885; 17.2-22.2) in Montevideo. After adjustment for key risk factors, the prevalence of COPD in Mexico City remained significantly lower than that in other cities.

INTERPRETATION

These results suggest that COPD is a greater health problem in Latin America than previously realised. Altitude may explain part of the difference in prevalence. Given the high rates of tobacco use in the region, increasing public awareness of the burden of COPD is important.

Asthma in Hispanics

Hispanic individuals trace their ancestry to countries that were previously under Spanish rule, including Mexico, large parts of Central and South America, and some Caribbean islands. Most--but not all--Hispanics have variable proportions of European, Amerindian, and African ancestry. Hispanics are diverse with regard to many factors, including racial ancestry, country of origin, area of residence, socioeconomic status, education, and access to health care. Recent findings suggest that there is marked variation in the prevalence, morbidity, and mortality of asthma in Hispanics in the United States and in Hispanic America. The reasons for differences in asthma and asthma morbidity among and within Hispanic subgroups are poorly understood but are likely due to the interaction between yet-unidentified genetic variants and other factors, including environmental tobacco smoke exposure, obesity, allergen exposure, and availability of health care. Barriers to optimal management of asthma in Hispanics in the United States and in Hispanic America include inadequate access to health care, suboptimal use of antiinflammatory medications, and lack of reference values for spirometric measures of lung function in many subgroups (e.g., Puerto Ricans). Future studies of asthma in Hispanics should include large samples of subgroups that are well characterized with regard to self-reported ethnicity, country of origin, place of birth, area of residence, and indicators of socioeconomic status. Because Hispanics are disproportionately represented among the poor in the United States, implementation of adequate access to health care and social reforms (e.g., improving housing conditions) would likely have a major impact on reducing asthma morbidity in this population.