This research was supported by the Jiangsu Provincial Department of Health General Program (H201506 (EA15)), and the Program for Advanced Talents within Six Industries of Jiangsu Province (2015-WSN-023 (IB15)). We thank Sarah Williams, PhD, from Liwen Bianji, Edanz Group China (http://www.liwenbianji.cn), for editing the English text of a draft of this manuscript.