Article History
First Online: 13 March 2018
Compliance with ethical guidelines
:
: C. Löffler, H. Sattler, U. Löffler, B.K. Krämer, and R. Bergner declare that they have no competing interests.
: 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. Informed consent was obtained from all individual participants included in the study.