The main etiologic factor for chronic bronchitis is cigarette smoke. Exposure to cigarette smoke is reported to induce goblet cell hyperplasia and mucus production. Mucin synthesis in airways has been reported to be regulated by the EGFR system. Peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a member of the ligand-activated nuclear receptor superfamily. PPAR-gamma is implicated in anti-inflammatory responses, but mechanisms underlying these varied roles remain ill-defined. Recently, reports have shown that upregulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) might be one of the mechanisms through which PPAR-gamma agonists exert their anti-inflammatory actions. However, no data are available on the role of PPAR-gamma in smoke-induced mucin production. In this study, we investigated the effect of PPAR-gamma agonist (rosiglitazone) on smoke-induced mucin production in NCI-H292 cells. Exposure to cigarette smoke causes a significant decrease in PTEN expression and increases dose-dependent EGFR-specific tyrosine phosphorylation, resulting in MUC5AC mucin production in NCI-H292 cells. PPAR-gamma agonists or specific inhibitors of phosphoinositide 3-kinase exert inhibition of cigarette smoke-induced mucin production, with the upregulation of PTEN signaling and downregulation of Akt expression. This study demonstrates that PPAR-gamma agonist functions as a regulator of epithelial cell inflammation that may result in reduction of mucin-producing cells in airway epithelium.
This article examines the relationship between preschool quality and children's early development in a sample of over 7,900 children enrolled in 578 preschools in rural Indonesia. Quality was measured by: (1) classroom observations using the Early Childhood Environment Rating Scale-Revised (ECERS-R), (2) teacher characteristics, and (3) structural characteristics of preschools. Children's development was measured using the Early Development Instrument (EDI). The article proposes two methodological improvements to preschool quality studies. First, an instrumental variable approach is used to correct for measurement error. Second, ECERS-R is adjusted to the local context by contrasting items with Indonesia's national preschool standards. Results show that observed classroom quality is a significant and meaningful positive predictor of children's development once models correct for measurement error and apply a locally-adapted measure of classroom quality. In contrast, teacher characteristics and structural characteristics are not significant predictors of child development, while holding observed classroom quality constant.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.