Funding for this research was provided by:
CAMS Innovation Fund for Medical Sciences (2017-I2M-1-009)
PUMC Youth Fund and the Fundamental Research Funds for the Central Universities (2017310049)
PUMC Innovation Fund for Graduate Student (2018-1002-01-21)
Received: 14 January 2021
Accepted: 18 April 2021
First Online: 4 May 2021
: The study protocol was approved by the Ethics Review Board of the Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences. The necessity for written informed consent was waived, as the data were analyzed anonymously.
: Not applicable.
: The authors declare that they have no competing interests.