1. Department of Stomatology II, Baoding No. 1 Central Hospital of Hebei Medical University, Baoding, Hebei 071000, P.R. China
2. Central Sterile Supply Department, Baoding No. 1 Central Hospital of Hebei Medical University, Baoding, Hebei 071000, P.R. China
3. Department of Internal Medicine, Graduate School of Hebei Medical University, Shijiazhuang, Hebei 050011, P.R. China
4. Department of Nephrology, Baoding No. 1 Central Hospital of Hebei Medical University, Baoding, Hebei 071000, P.R. China