title: Acute effects of walking environment and GSTM1 variants in children with asthma.
abstract: BACKGROUND
  Exercise in air polluted by traffic emissions may aggravate airway inflammation in children with asthma, particularly those who produce decreased glutathione-S transferase (GST) as a result of GSTM1 gene deletion.
  
  
  OBJECTIVE
  This pilot crossover study investigated whether children with asthma experience more airway changes when exercising outdoors near roadways than when exercising indoors. It also examined differences in risk between children with and without GSTM1 deletion.
  
  
  METHODS
  Children between the ages of 5 and 12 years were assigned to groups and walked daily for 1 week in each exercise condition. Airway inflammation indicated by exhaled nitric oxide (eNO) and pulmonary functions measured as forced expiratory volume in 1 s (FEV1) and mid-expiratory flow rate were measured at baseline and at three intervals during the walking program. Independent variables of interest included walking condition (place), time of walking, genotype, and particulate matter (PM) exposure.
  
  
  RESULTS
  A linear mixed models approach was used to investigate the contributions of targeted variables to respiratory outcomes. Results indicated that walking location and ambient level of ultrafine particulates during walking influenced function of small airways. Absence of one or both alleles for the GSTM1 gene did not influence airway function acutely.
  
  
  CONCLUSIONS
  Mid-expiratory flow (FEF(25-75)) may be more informative than FEV1 in studies of acute lung function changes in children with asthma. Further study of the effects of varied environmental conditions on lower airway function of children is needed to optimize exercise experiences for urban children with asthma.
authors.affiliation: College of Nursing, University of Texas at Arlington, Arlington, TX 76019, USA. pnewcomb@uta.edu
authors.forename: Patricia
authors.initials: P
authors.lastname: Newcomb
authors.forename: Andrew
authors.initials: A
authors.lastname: Hunt
authors.forename: Pamela
authors.initials: P
authors.lastname: Rast
authors.forename: Denise
authors.initials: D
authors.lastname: Cauble
authors.forename: Nancy
authors.initials: N
authors.lastname: Rowe
authors.forename: Jianling
authors.initials: J
authors.lastname: Li
mesh_terms: D000393:Air Pollutants / Q000633:toxicity; D001249:Asthma / Q000201:enzymology / Q000235:genetics* / Q000503:physiopathology; D002648:Child; D002675:Child, Preschool; D018592:Cross-Over Studies; D005260:Female; D005982:Glutathione Transferase / Q000235:genetics*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D012129:Respiratory Function Tests; D001335:Vehicle Emissions; D016138:Walking
chemical_list: D000393:Air Pollutants; D005982:Glutathione Transferase; D001335:Vehicle Emissions