1. Department of Paediatric Pathology, Childrens' Hospital, University of Helsinki, SF-00290 Helsinki, Finland.
2. Institute of Biotechnology, University of Helsinki, Helsinki, Finland, and Institute of Chemical Physics and Biophysics, Estonian Academy of Sciences, Tallinn, Estonia.
3. Department of Pathology, University of Helsinki, Helsinki, Finland
4. Institute of Pedodontics and Orthodontics, University of Helsinki, Helsinki, Finland.