Received: 29 September 2020
Accepted: 27 January 2021
First Online: 16 February 2021
Compliance with ethical standards
: Drs. Tatsunori Satoh, Hirotoshi Ishiwatari, Shinya Kawaguchi, Naofumi Shirane, Hiroyuki Matsubayashi, Junichi Kaneko, Junya Sato, Kazuma Ishikawa, Takuya Otsu, Shuzo Terada, Hiroyuki Ono, and Masataka Kikuyama have no conflicts of interest or financial ties to declare.