Funding for this research was provided by:
the National Nature Science Foundation of China (81571219)
Beijing Municipal Science and Technology Commission (Z151100003915126)
Article History
Received: 17 February 2020
Accepted: 28 May 2020
First Online: 8 July 2020
Ethics approval and consent to participate
: The study was performed in accordance with the ethical standards of the responsible committees on human experimentation and approved by the Institutional Review Board (no. 2011[419]). Informed consent for all examinations was obtained from the patients or their guardians. The protocol in the study strictly followed the rules of the Declaration of Helsinki.
: Applicable.
: The authors declare no conflicts of interest.