Article History
Received: 10 September 2018
Accepted: 11 December 2018
First Online: 15 January 2019
Compliance with Ethical Standards
: This study has got the approval from the Ethics Committee for Animal Experiments in Linyi Central Hospital, which was in strictly obedience to the <i>Guide for the Care and Use of Laboratory Animals</i> published by the National Institute of Health in the USA (Health CitationRef removed).
: The authors declare that they have no conflict of interest.