Text and Data Mining valid from 2018-10-22
Received: 11 July 2018
Accepted: 14 September 2018
First Online: 22 October 2018
Compliance with ethical guidelines
: U. Wollina, A. Koch, and B. Heinig declare that they have no competing interests.
: 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 1975, as revised in 2008.