Received: 26 June 2019
Accepted: 11 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: The study was approved by the ethics committee of the Ruhr-University Bochum (No. 4929–14). All experimental work was conducted in accordance with the Declaration of Helsinki. Subjects gave written informed consent to participation.
: Not applicable.
: The authors declare that they have no competing interests.