Received: 18 May 2017
Accepted: 16 January 2018
First Online: 23 February 2018
Ethics approval and consent to participate
: Experimental procedures concerning animals were approved by the Ethics Committee of Beijing Normal University (BNU/EC/01/2011). All experimental procedures were performed in keeping with National Institutes of Health Guideline for the care and use of laboratory animals (NIH Publications No. 80–23, revised 1996).
: Not applicable.
: All authors declare that they have no competing interests.
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