ABSTRACT
Based on the panel data of 259 cities across China from 2011 to 2019, the study investigates the long-run impact of digital economy on regional pollution intensity by employing multiple models. The estimation results reveal that (1) the relatively heavily polluted areas are concentrated in the north, especially in the northeast of China; the overall pollution intensity is decreasing year by year at the national level; (2) the development of digital economy can significantly contribute to the reduction of regional pollution intensity and it has a statistically significant negative spatial spillover effect on the pollution intensity of neighboring cities; (3) mechanism analysis shows that the development of digital economy not only has a direct effect on the reduction of pollution intensity but also promotes the reduction through the channel of industrial structure upgrading and green technology progress; (4) the results of threshold model suggest that as the level of development of the digital economy increases, its marginal inhibitory effect of promoting the decrease in pollution intensity will diminish; (5) heterogeneity analysis shows that the development of digital economy makes the strongest marginal contribution to pollution intensity reduction in the northeast region. Finally, the conclusions remain valid after controlling for exogenous shocks such as "smart city" policy, various robustness, and endogeneity tests.
Subject(s)
Environmental Pollution , Industry , China , Cities , Policy , Economic DevelopmentABSTRACT
Background To study diabetic retinopathy (DR) related risk factors is very important in the prevention of DR.Platelet endothelial cell adhesion molecule-1 (PECAM-1) is an important mediator that mediates high blood glucose-induced vascular diseases in diabetic patients.However,its mechanism is still below understood.Objective This clinical study was to investigate the effect of serum level changes of PECAM-1 on DR in type 2 diabetic patients.Methods Fifty-four patients with type 2 diabetes were enrolled from the endocrinology department of the Third People' s Hospital of Nantong City.Fundus examination was performed using the ophthalmoscope and fundus fluorescence angiography (FFA) on all the patients,and these patients were grouped as the non-DR (NDR)group (18 cases),non-proliferative DR(NPDR) group (20 cases) and proliferative DR group (PDR) (16 cases) based on the DR staging criterion of the Chinese Medical Association (1987 version).Eighteen age-and gender-matched normal subjects served as the normal control group.Peripheral blood was collected,and serum PECAM-1 levels were assayed using ELISA.Serum HbA1c levels were detected using the high performance liquid colorimetric(HPLC) method.The correlation of serum PECAM-1 level with serum HbA1c level was analyzed.All results were compared among the groups.Results The serum PECAM-1 levels were (10.907 ± 2.792),(7.024 ±2.377),(5.231 ± 1.816) and (3.817 ± 1.045) μg/L,respectively,in the PDR group,NPDR group,NDR group and normal control group,showing a significant difference among the 4 groups (F =12.630,P =0.02).Serum PECAM-1 content was significantly higher in the PDR group when compared with the NPDR group,NDR group and normal control group (P＜0.05).The serum HbA1c levels were (12.596±3.148)％,(9.118±3.356)％,(5.491±1.017)％ and (4.992 ± 0.725)％ in the PDR group,NPDR group,NDR group and normal control group,respectively,with a significant difference among these 4 groups (F =7.130,P =0.015),and those in the PDR group and NPDR group were significantly elevated in comparison with the NDR group and normal control group (P＜0.05).Significantly positive correlations were seen between serum PECAM-1 level and HbA1 c level in the PDR group,NPDR group and NDR group (r=0.799,P＜0.01 ;r =0.647,P＜0.01 ;r =0.685,P＜0.01).Significantly more patients with a disease course of ≥ 10 years were in the NPDR group in comparison with the PDR group (P =0.023).Conclusions Increase of serum PECAM-1 level is closely associated with blood glucose level,and it is an important factor in the pathogenesis and development of DR.These results imply that control of blood glucose is crucial for the prevention of DR in patient with type 2 diabetes.