الفهرس 
Pediatric AsthmaOnly 14 pages are availabe for public view
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Abstract
Asthma is a chronic, heterogeneous disease with symptoms
that include wheeze, cough (particularly at night and during
exertion), dyspnea, chest tightness, variable airways obstruction and
bronchial hyper-responsiveness (BHR).
Exercise-induced bronchoconstriction (EIB) is defined as
transient narrowing of the airways that follow vigorous exercise. EIB
is a common manifestation of asthma in children and adolescents,
occurring in up to 90% of asthmatic children. It`s prevelance in
general pediatric population is between 6% and 20%.
It has been suggested that exercise causes airway narrowing
by the loss of water through evaporation, resulting in thermal and
osmotic effects of dehydration in the airways. However, the precise
mechanism by which increased osmolarity leads to airflow limitation
is unknown. It has been proposed that mediators, such as histamine,
leukotrienes, and prostanoids, released from the mast cells and
epithelial cells in response to a hyperosmolar stimulus may be
responsible for the bronchospasm.
Lipoxins were the first agents to be identified as antiinflammatory
endogenous lipid mediators involved in the resolution
of inflammation. They inhibit granulocyte recruitment and
activation, cytokine and chemokine production, and biosynthesis of
pro-inflammatory lipid mediators, stimulate the clearance of
apoptotic leukocytes, and block edema formation.