Funding for this research was provided by:
Text and Data Mining valid from 2019-01-04
Received: 3 September 2018
Accepted: 14 December 2018
First Online: 4 January 2019
Compliance with ethical standards
: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. This study was approved by the institutional review board of Tokyo Medical and Dental University (M2000-1887).
: Written informed consent was provided by all participants.