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Article History

Received: 25 November 2017

Accepted: 4 April 2018

First Online: 13 April 2018

Ethics approval and consent to participate

: This study was carried out in accordance with the recommendations of the Ethics Committee of the Medical Faculty of the Leipzig University (approvals no. 148–2005, 159–12-21,052,012, 017–12-23,012,012). All subjects gave written informed consent in accordance with the Declaration of Helsinki.

: The authors declare that they have no competing interests.

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