Funding for this research was provided by:
Polish Ministry of Science and Higher Education (290/W-PURE/2008/0)
Wroclaw Medical University (STM.E110.17.019)
Received: 29 May 2019
Accepted: 20 December 2019
First Online: 30 December 2019
Ethics approval and consent to participate
: All individuals were volunteers and signed an informed consent form before any study procedures were performed. The study was approved by the Polish Ethics Committee (No. KB-443/2006).
: Not applicable.
: The authors declare that they have no competing interests.