1. Department of Medicine, Imperial College London, London W12 0NN, UK.
2. Faculty of Medical Technology, Mahidol University, Bangkok 10700, Thailand.
3. Pediatric Department, Khon Kaen Hospital, Khon Kaen 4000, Thailand.
4. Pediatric Department, Songkhla Hospital, Songkhla 90100, Thailand.
5. BIOTEC, NSTDA, Phatumthani 12120, Thailand.
6. Faculty of Medicine, Siriraj Hospital, Mahidol University, Bangkok 10700, Thailand.