Long-term exposures to air pollutants affect in children: a longitudinal study.

Annual average PM and NO were associated with airway inflammation as measured by FeNO in schoolchildren, adding new evidence that long-term exposure affects FeNO beyond the well-documented short-term effects.

Patterns and determinants of exhaled nitric oxide trajectories in schoolchildren over a 7-year period.

Fractional exhaled nitric oxide ( ), a marker of allergic airway inflammation, is used in respiratory research and asthma clinical care; however, its trajectory with increasing age during childhood has not been well characterised. We examined longitudinally during a period of important somatic growth to describe trajectories across childhood and adolescence in healthy participants and evaluate clinical factors as potential determinants of trajectories. was collected at six visits over 8 years in a population-based cohort of 1791 schoolchildren without asthma (median age at entry 8.

Impact of different fixed flow sampling protocols on flow-independent exhaled nitric oxide parameter estimates using the Bayesian dynamic two-compartment model.

Exhaled nitric oxide (FeNO) is an established respiratory biomarker with clinical applications in the diagnosis and management of asthma. Because FeNO depends strongly on the flow (exhalation) rate, early protocols specified that measurements should be taken when subjects exhaled at a fixed rate of 50 ml/s. Subsequently, multiple flow (or "extended") protocols were introduced which measure FeNO across a range of fixed flow rates, allowing estimation of parameters including C NO and C NO which partition the physiological sources of NO into proximal airway wall tissue and distal alveolar regions (respectively).

Genetic and epigenetic susceptibility of airway inflammation to PM in school children: new insights from quantile regression.

Background: The fractional concentration of exhaled nitric oxide (FeNO) is a biomarker of airway inflammation that has proved to be useful in investigations of genetic and epigenetic airway susceptibility to ambient air pollutants. For example, susceptibility to airway inflammation from exposure to particulate matter with aerodynamic diameter < =2.5 μm (PM) varies by haplotypes and promoter region methylation in inducible nitric oxide synthase (iNOS encoded by NOS2).

Bayesian estimation of physiological parameters governing a dynamic two-compartment model of exhaled nitric oxide.

The fractional concentration of nitric oxide in exhaled breath (fe) is a biomarker of airway inflammation with applications in clinical asthma management and environmental epidemiology. fe concentration depends on the expiratory flow rate. Standard fe is assessed at 50 mL/sec, but "extended NO analysis" uses fe measured at multiple different flow rates to estimate parameters quantifying proximal and distal sources of NO in the lower respiratory tract.

Traffic-related air pollution and alveolar nitric oxide in southern California children.

Mechanisms for the adverse respiratory effects of traffic-related air pollution (TRAP) have yet to be established. We evaluated the acute effects of TRAP exposure on proximal and distal airway inflammation by relating indoor nitric oxide (NO), a marker of TRAP exposure in the indoor microenvironment, to airway and alveolar sources of exhaled nitric oxide (FeNO).FeNO was collected online at four flow rates in 1635 schoolchildren (aged 12-15 years) in southern California (USA) breathing NO-free air.

Determinants of Children's Exhaled Nitric Oxide: New Insights from Quantile Regression.

While the fractional concentration of exhaled nitric oxide (FeNO) has proven useful in asthma research, its exact role in clinical care remains unclear, in part due to unexplained inter-subject heterogeneity. In this study, we assessed the hypothesis that the effects of determinants of the fractional concentration of exhaled nitric oxide (FeNO) vary with differing levels of FeNO. In a population-based cohort of 1542 school children aged 12-15 from the Southern California Children's Health Study, we used quantile regression to investigate if the relationships of asthma, socio-demographic and clinical covariates with FeNO vary across its distribution.

Spirometry effects on conventional and multiple flow exhaled nitric oxide in children.

Objective: Clinical and research settings often require sequencing multiple respiratory tests in a brief visit. Guidelines recommend measuring the concentration of exhaled nitric oxide (FeNO) before spirometry, but evidence for a spirometry carryover effect on FeNO is mixed. Only one study has investigated spirometry carryover effects on multiple flow FeNO analysis.

Longitudinal effects of air pollution on exhaled nitric oxide: the Children's Health Study.

Objectives: To assess the effects of long-term variations in ambient air pollutants on longitudinal changes in exhaled nitric oxide (FeNO), a potentially useful biomarker of eosinophilic airway inflammation, based on data from the southern California Children's Health Study.

Methods: Based on a cohort of 1211 schoolchildren from eight Southern California communities with FeNO measurements in 2006-2007 and 2007-2008, regression models adjusted for short-term effects of air pollution were fitted to assess the association between changes in annual long-term exposures and changes in FeNO.

Results: Increases in annual average concentrations of 24-h average NO2 and PM2.

Estimation of parameters in the two-compartment model for exhaled nitric oxide.

The fractional concentration of exhaled nitric oxide (FeNO) is a biomarker of airway inflammation that is being increasingly considered in clinical, occupational, and epidemiological applications ranging from asthma management to the detection of air pollution health effects. FeNO depends strongly on exhalation flow rate. This dependency has allowed for the development of mathematical models whose parameters quantify airway and alveolar compartment contributions to FeNO.

Associations of children's lung function with ambient air pollution: joint effects of regional and near-roadway pollutants.

Background: Previous studies have reported adverse effects of either regional or near-roadway air pollution (NRAP) on lung function. However, there has been little study of the joint effects of these exposures.

Objectives: To assess the joint effects of NRAP and regional pollutants on childhood lung function in the Children's Health Study.

Multiple-flow exhaled nitric oxide, allergy, and asthma in a population of older children.

Unlabelled: "Extended" (multiple-flow) measurements of exhaled nitric oxide (FeNO) potentially can distinguish proximal and distal airway inflammation, but have not been evaluated previously in large populations. We performed extended NO testing within a longitudinal study of a school-based population, to relate bronchial flux (J'awNO) and peripheral NO concentration (CalvNO) estimates with respiratory health status determined from questionnaires. We measured FeNO at 30, 50, 100, and 300 ml/sec in 1,640 subjects aged 12-15 from eight communities, then estimated J'awNO and CalvNO from linear and nonlinear regressions of NO output versus flow.

Residential traffic-related pollution exposures and exhaled nitric oxide in the children's health study.

Background: The fractional concentration of nitric oxide in exhaled air (FeNO) potentially detects airway inflammation related to air pollution exposure. Existing studies have not yet provided conclusive evidence on the association of FeNO with traffic-related pollution (TRP).

Objectives: We evaluated the association of FeNO with residential TRP exposure in a large cohort of children.

Extended exhaled nitric oxide analysis in field surveys of schoolchildren: a pilot test.

Extended exhaled nitric oxide (eNO) analysis can distinguish proximal and distal airway contributions to FeNO. Thus, it has the potential to detect effects of different environmental influences, allergic phenotypes, and genetic variants on proximal and distal airways. However, its feasibility in field surveys has not been demonstrated, and models for estimating compartmental NO contributions have not been standardized.

Exhaled nitric oxide in a population-based study of southern California schoolchildren.

Background: Determinants of exhaled nitric oxide (FeNO) need to be understood better to maximize the value of FeNO measurement in clinical practice and research. Our aim was to identify significant predictors of FeNO in an initial cross-sectional survey of southern California schoolchildren, part of a larger longitudinal study of asthma incidence.

Methods: During one school year, we measured FeNO at 100 ml/sec flow, using a validated offline technique, in 2568 children of age 7-10 yr.

Relationships of online exhaled, offline exhaled, and ambient nitric oxide in an epidemiologic survey of schoolchildren.

Unlabelled: Field measurements of exhaled nitric oxide (FeNO) and ambient nitric oxide (NO) are useful to assess both respiratory health and short-term air pollution exposure. Online real-time measurement maximizes data quality and comparability with clinical studies, but offline delayed measurement may be more practical for large epidemiological studies. To facilitate cross-comparison in larger studies, we measured FeNO and concurrent ambient NO both online and offline in 362 children at 14 schools in 8 Southern California communities.

Effects of ambient air pollutants on asthma medication use and wheezing among fourth-grade school children from 12 Southern California communities enrolled in The Children's Health Study.

To investigate the effects of 12 monthly average air pollution levels on monthly prevalence of respiratory morbidity, the authors examined retrospective questionnaire data on 2034 4th-grade children from 12 Southern California communities that were enrolled in The Children's Health Study. Wheezing during the spring and summer months was associated with community levels of airborne particulate matter with a diameter < or = 10 microm (PM10) (odds ratio (OR) = 2.91; 95% confidence interval (CI) = 1.

TNF-308 modifies the effect of second-hand smoke on respiratory illness-related school absences.

Rationale: Exposure to second-hand smoke (SHS) has been associated with increased risk of respiratory illness in children including respiratory illness-related school absences. The role of genetic susceptibility in risk for adverse effects from SHS has not been extensively investigated in children.

Objective: To determine whether the tumor necrosis factor (TNF) G-308A genotype influences the risk for respiratory illness-related school absences associated with SHS exposure.

Effects of early onset asthma and in utero exposure to maternal smoking on childhood lung function.

Both in utero exposures to maternal smoking and asthma are associated with chronic deficits in lung function. We hypothesized that in utero exposure affects lung function in children without asthma and synergistically affects children with early onset asthma. To investigate effects of in utero exposure and age at asthma diagnosis on lung function, we examined longitudinal medical history, tobacco smoke exposure, and lung function data from 5,933 participants in the Children's Health Study.

Effects of glutathione S-transferase P1, M1, and T1 on acute respiratory illness in school children.

The relationships between glutathione S-transferase (GST) M1, GSTT1, and GSTP1 genotypes and acute respiratory illness were investigated in a cohort of fourth grade school children aged 9-11 years who resided in 12 southern California communities. We used respiratory illness-related absences as a measure of respiratory illness occurrence. We ascertained respiratory illness-related school absences using an active surveillance system from January 1996 through June 1996.

Impact of respiratory illness on expiratory flow rates in normal, asthmatic, and allergic children.

We examined the effects of current respiratory illness (RI) on pulmonary function (PF) in 1,103 subjects who underwent spirometry at schools twice within a 4-month period. Before spirometry, subjects were asked if they had a "cold or other chest illness" during the previous month, and if so, whether they had fully recovered. Those who had not recovered were considered to have an RI.

Association between air pollution and lung function growth in southern California children: results from a second cohort.

A cohort of 1,678 Southern California children, enrolled as fourth graders in 1996, was followed for 4 years to determine whether the growth in lung function of the children was associated with their exposure to ambient air pollutants. These subjects comprised the second cohort of fourth grade children participating in the Children's Health Study. Significant deficits in lung function growth rate were associated with exposure to acid vapor, NO(2), particles with aerodynamic diameter less than 2.

Indoor risk factors for asthma in a prospective study of adolescents.

Background: The risk of asthma associated with pets and other indoor exposures has been examined in both cross-sectional and prospective studies of younger children. However, there has been little investigation of the effect of the indoor environment on incident asthma in adolescents.

Methods: Risk factors for the development of asthma were examined in a cohort of 3535 Southern California school children with no history of asthma at 1993 entry into the study, who were followed for up to 5 years.