Helmus, Janine
Bajanowski, Thomas
Poetsch, Micaela
Article History
Received: 18 August 2015
Accepted: 20 October 2015
First Online: 27 October 2015
Compliance with ethical standards
: All samples were obtained after informed consent and with approval of the Medical Ethics Committee at the University of Duisburg-Essen in accordance with the Declaration of Helsinki and national laws.