Pediatric research
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Multicenter Study
Post-exercise airway narrowing in healthy primary school children.
Changes in lung function after exercise in healthy primary school children have mostly been described in field studies. More complete description and insight into relevant mechanisms may be provided in lung function laboratory. The aim was to describe airway caliber and response to deep inhalation (DI) after exercise in healthy primary school children. ⋯ DI induced significant decrease in Rrs (p = 0.01) that was not different between E5 and baseline. Healthy primary school children exhibit changes in Rrs and spirometry after exercise indicating small but significant airway narrowing. The response to DI similar at baseline and E5 suggests airway narrowing from hyperemia in the bronchial wall rather than airway smooth muscle constriction.
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Premature newborn baboons [125 d (67%) gestation], exposed to a moderate-size patent ductus arteriosus (PDA) [pulmonary-to-systemic blood-flow-ratio (Qp/Qs) = 1.8] for 14 d, have impaired pulmonary function and arrested alveolar development and surface area when compared with age matched fetuses (140 d gestation). Pharmacologic closure of the PDA reduces the detrimental effects of preterm delivery on pulmonary function and surface area. We used preterm baboons (delivered at 125 d gestation and ventilated for 14 d) to study the effects of surgical PDA ligation on pulmonary function and alveolar surface area. ⋯ Alveolar surface area measurements were made by digital image analysis and compared with measurements made from fetal lungs at 125 d (n = 6) and 140 d (n = 7) gestation. PDA ligation failed to improve the postnatal arrest in alveolar surface area. In contrast with pharmacologic closure of the PDA, surgical closure failed to improve either pulmonary function or alveolar surface area in baboons with a moderate PDA shunt.
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To determine whether glutamine (Gln) reduces the ratio of oxidized to total glutathione (GSSG/GSH) and extracellular signal-regulated kinase (ERK1/2) activation in dystrophic muscle. Four-week old mdx mice, an animal model for Duchenne muscular dystrophy and control (C57BL/10) received daily intraperitoneal injections of l-Gln (500 mg/kg/d) or 0.9% NaCl for 3 d. GSH and GSSG concentrations in gastrocnemius were measured using a standard enzymatic recycling procedure. ⋯ Exogenous Gln decreased muscle free Glu and Gln + Glu in mdx only, whereas Gln was not affected. In conclusion, exogenous Gln reduces GSSG/GSH and ERK1/2 activation in dystrophic skeletal muscle of young mdx mice, which is associated with decreased muscle free Glu and Gln + Glu. This antioxidant protective mechanism provides a molecular basis for Gln's antiproteolytic effect in Duchenne muscular dystrophy children.