Funding for this research was provided by:
Zhejiang Provincial Natural Science Foundation of China (LY15H090018)
Ningbo Natural Science Foundation (2014A610253)
Received: 14 September 2017
Accepted: 11 January 2018
First Online: 17 January 2018
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: No ethical approval or patient consent was required because all analyses were based on previous published studies.
: Not applicable.
: The authors declare that they have no competing interests.
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