Received: 27 June 2019
Accepted: 7 April 2020
First Online: 15 April 2020
Ethics approval and consent to participate
: This study was carried out in compliance with the Declaration of Helsinki. All subjects provided written informed consent for inclusion in the study, which was approved by the institutional review board of Akita University (Ethical Approval No. 1341).
: Not applicable.
: No competing financial interests exist.