Funding for this research was provided by:
Japan Society for the Promotion of Science (grant number JP 18K17768)
Received: 14 February 2019
Accepted: 18 April 2019
First Online: 3 May 2019
Ethics approval and consent to participate
: The study protocol was approved by the institutional review board of Niigata University of Health and Welfare (no. 17798–170285). Written informed consent was obtained from each subject.
: Not applicable.
: The authors declare that they have no competing interests.
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