Vasilev, Georgi http://orcid.org/0000-0002-6314-6889
Ivanova, Mariana http://orcid.org/0000-0002-0441-3043
Ivanova-Todorova, Ekaterina http://orcid.org/0000-0002-1833-838X
Tumangelova-Yuzeir, Kalina http://orcid.org/0000-0001-6143-7538
Krasimirova, Ekaterina http://orcid.org/0000-0003-1968-5962
Stoilov, Rumen http://orcid.org/0000-0002-6340-9650
Kyurkchiev, Dobroslav http://orcid.org/0000-0002-8257-7764
Funding for this research was provided by:
Medical University of Sofia (128/2018)
Article History
Received: 28 February 2019
Accepted: 25 March 2019
First Online: 3 April 2019
Compliance with ethical standards
:
: Authors report no conflict of interest concerning this article.
: All experiments performed in this study involving human participants were approved by the institutional and national research committee and complied with the Helsinki Declaration of 1964 and its later amendments (2008).
: Voluntarily signed informed consent was obtained from all participants in accordance with the ethical recommendations of the Helsinki Declaration before entering the study.