Specific author contributions: Conception and design: Wei Tao. Acquisition, analysis and interpretation of data and statistical analysis: Haixia Wang. Drafting the article: Haixia Wang. Critically revising the article: Wei Tao. Reviewed submitted version of manuscript: Wei Tao. Approved the final version of the manuscript on behalf of all authors: Haixia Wang, Wei Tao. All authors had approved the final draft submitted.