Funding for this research was provided by:
National Natural Science Foundation of China (81471210)
Key Project of Beijing Municipal Science & Technology Commission (D161100003816004)
Received: 30 October 2018
Accepted: 30 January 2019
First Online: 7 March 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Beijing Tiantan Hospital, Capital Medical University. All procedures performed in this study were in accordance with the ethical standards of the institutional research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. For this type of study formal consent is not required.
: Written informed consents were obtained from all participants or their legally authorized representatives and privacy of patients was effectively protected.
: All authors certify that we have no affiliations with or involvement in any organization or entity with any financial interest (such as honoraria; educational grants; participation in speakers’ bureaus; membership, employment, consultancies, stock ownership, or other equity interest; and expert testimony or patent-licensing arrangements) or non-financial interest (such as personal or professional relationships, affiliations, knowledge, or beliefs) in the subject matter or materials discussed in this manuscript.