Effects of antenatal dexamethasone on antioxidant enzymes and nitric oxide synthase in the rat lung.

We investigated the effects of prenatal dexamethasone (DEX) administration on antioxidant enzymes (AOEs) and nitric oxide synthase (NOS) in fetal and neonatal rat lungs. DEX (1 mg/kg, s.c., for 2 days) or vehicle alone was administered to pregnant rats, and the lungs of fetuses on days 19 and 21 of gestation and of 1- and 3-day-old neonates were examined. We measured protein levels of the AOEs manganese superoxide dismutase and copper-zinc superoxide dismutase (Mn SOD and Cu-Zn SOD), glutathione peroxidase (GSH-Px), catalase (CAT), and inducible and endothelial nitric oxide synthase (i-NOS and e-NOS). Mn SOD, GSH-Px, and e-NOS expression gradually increased with increasing gestational and postnatal age in the lungs of the control groups. Cu-Zn SOD, CAT, and i-NOS expression did not change with increasing gestational and postnatal age in the lungs of the control groups. DEX administration had significant effects on i-NOS and e-NOS protein and mRNA expression. The increased Mn SOD, GSH-Px, and e-NOS expressions during the perinatal period suggests that antenatal developmental changes in AOEs in the lungs of premature fetuses could be reduced by reactive oxygen species-mediated injury at birth. Furthermore, antenatal glucocorticoid treatment may accelerate the development of lungs via the two types of NOS.

Spontaneous platelet aggregation in Kawasaki disease using the particle counting method.

BACKGROUND: Platelet aggregation is generally measured by the optical density method. This method is not very sensitive in detecting platelet activation because of the poor correlation between the formation of platelet aggregates and light transmission, and inability to detect small platelet aggregates. Recently, a new method was developed that detects small platelet aggregates formed in the early phase of platelet aggregation by means of a particle counting technique using light scattering. METHODS: The present study used the particle counting method to measure spontaneous platelet aggregation (SPA) produced by agitation with a stirrer bar without agonists in patients with Kawasaki disease (KD) and children's thrombotic disease, and compared the results with the conventional optical density method. RESULTS: Using the particle counting method, significantly higher SPA rates were found before treatment than in healthy adults and at the other stages of treatment. A similar tendency was noted with the optical density method; however, the positive rate of SPA was significantly higher with the particle counting method in each stage except the second stage, which was the period from the start of gamma-globulin therapy to 20 days. CONCLUSION: These results indicate that enhanced platelet aggregation is noted at a high frequency before treatment of KD and that the particle counting method is superior to the optical density method in detecting enhanced platelet aggregation.