Conflict of interest

Haruka Okazaki, Hitoshi Nagai, Shinichi Okuda, Takeshi Ueyama, and Yasuhiro Ikeda declare that they have no conflict of interest.

Human rights statements and informed consent

All procedures followed were in accordance with the ethical standards of the responsible committee on human experimentation (institutional and national) and with the Helsinki Declaration of 1964 and later versions. Informed consent was obtained from all patients for being included in the study.