No abstract

Background A multitude of epidemiological studies have shown that ambient fine particulate matter 2.5 (diameter < 2.5um; PM 2.5 ) was associated with increased morbidity and mortality of chronic obstructive pulmonary disease (COPD). However, the underlying associated mechanisms have not yet been elucidated. We conducted this study to investigate the role of PM 2.5 in the development of COPD and associated mechanisms. Methods We firstly conducted a cross-sectional study in Chinese han population to observe PM 2.5 effects on COPD morbidity. Then, in vitro, we incubated human bronchial epithelial cells to different concentrations of PM 2.5 for 24 h. The expression levels of IL-6 and IL-8 were detected by ELISA and the levels of MMPs, TGF-β1, fibronectin and collagen was determined by immunoblotting. In vivo, we subjected C57BL/6 mice to chronic prolonged exposure to PM 2.5 for 48 weeks to study the influence of PM 2.5 exposure on lung function, pulmonary structure and inflammation. Results We found that the effect of PM 2.5 on COPD morbidity was associated with its levels and that PM 2.5 and cigarette smoke could have a synergistic impact on COPD development and progression. Both vitro and vivo studies demonstrated that PM 2.5 exposure could induce pulmonary inflammation, decrease lung function, and cause emphysematous changes. Furthermore, PM 2.5 could markedly aggravated cigarette smoke-induced changes. Conclusions In short, we found that prolonged chronic exposure to PM 2.5 resulted in decreased lung function, emphysematous lesions and airway inflammation. Most importantly, long-term PM 2.5 exposure exacerbateed cigarette smoke-induced changes in COPD.

This paper examines international trade and foreign direct investment as channels for technology diffusion among industrialized countries. We find strong empirical support for capital goods trade as a channel for international technology diffusion and some evidence that multinational enterprises (outward FDI) transmit foreign technology back to the home country. We find no evidence that inward FDI is a significant channel for international technology diffusion among industrialized countries. Our results also show that technology diffuses in disembodied forms, with countries that are farther from the world technology frontier benefiting more.