xin liu blood sampling room, second affiliated hospital of harbin medical university, harbin 150086, china. xu he dept. of hepatopancreatobiliary surgery, first affiliated hospital of harbin medical university, harbin 150001, china. ling li disaster preparedness and relief center of red cross society of heilongjiang, harbin 150008, china. lili huang dept. of neurology, second affiliated hospital of harbin medical university, harbin 150086, china. zhaojun liu dept. of neurology, second affiliated hospital of harbin medical university, harbin 150086, china.