1. Medical School, Democritus University of Thrace, Alexandroupolis, Greece
2. Department of Pneumonology, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
3. Second Department of Internal Medicine, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
4. Laboratory of Hygiene and Environmental Protection, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
5. Department of Clinical Biochemistry, Royal Free Hospital, University College London, London, United Kingdom