Funding for this research was provided by:
National Natural Science Foundation of China (81571869)
Received: 10 March 2019
Accepted: 31 May 2019
First Online: 10 June 2019
Ethics approval and consent to participate
: The study protocol was approved by the Medical Ethics Committee of the First Affiliated Hospital of Dalian Medical University (Dalian, China). Written informed consent was obtained from all patients (or their relatives) upon their initial admission to the hospital and from healthy volunteers.
: Not applicable.
: The authors declare that they have no competing interests.