Funding for this research was provided by:
National Natural Science Fund of China (81572974)
First Online: 29 January 2018
Compliance with ethical standards
: This project was approved by the Ethics Committee of the Tangdu Hospital, Fourth Military Medical University. Ethical approval was obtained from the Ethics Committee of Tangdu Hospital, Fourth Military Medical University (TDLL-20151209), and informed consent was not required.
: The authors declare that they have no conflict of interest.