Objective : To compare acute ulcerative colitis (UC) model induced by dextran sulfate sodium ( DSS) at 1. 5% and 3. 0% concentrations and obtain a cost-effective modeling scheme with low mortality． Methods: C57BL /6J mice were randomly divided into control group，1. 5% and 3. 0% DSS group．The mice in control group drank sterilized water and the mice in each group of DSS drank the corresponding concentration of DSS solution，all mice were treated for 7 days．And all mice drank sterilized water on day 8 to 14．The blood stool of mice was ob- served and the disease activity index，the percentage of body weight loss and the percent of survival of mice were calculated on day 1 to 14．Mice were sacrificed on day 8．The spleen index was calculated and the length of colon was measured ; HE staining was used to observe the histopathological changes of colon ; The expressions of tight junc- tion protein Claudin-1 and Occludin in colon tissue were detected by immunohistochemistry ; Immunofluorescence detected the ratio of macrophage in colon tissue ; Levels of tumor necrosis factor-α (TNF-α) in serum and colon tis- sue homogenates were detected by ELISA. Results : Compared with the control group，both mice of 1. 5% DSS group and mice of 3. 0% DSS group showed similar clinical and pathological features to human UC ; The colon lengths were both shortened (P＜0. 01) ; The expressions of Claudin-1 and Occludin in colon tissue both decreased (P＜0. 01) ; Spleen index increased (P＜0. 01) ; The proportion of macrophages in colon tissue increased (P＜0. 01) ; Levels of TNF-α in serum and colon tissue homogenates both increased (P ＜0. 01 ) ．The percent of survival of 1. 5% DSS mice within 14 days was higher than that of 3. 0% DSS mice． Conclusion The acute UC model can be established efficiently and economically by giving 1. 5% concentration of DSS solution in mice for 7 days.

Objective : To investigate the expression and clinical significance of tryptophan⁃2 ,3 ⁃dioxygenase⁃2 (TDO2) in peripheral blood mononuclear cells ( PBMC) and synovial tissue of patients with rheumatoid arthritis (RA) . Methods : A total of 40 RA patients were selected as the RA group , and 36 healthy subjects were selected as the normal control group during the same period. In RA group and control group PBMC , TDO2 expression was detected by flow cytometry. Immunofluorescence was applied to observe TDO2 expression in synovial tissue of RA groups and control group. The correlation was analyzed between TDO2 expression in PBMC and their inflammatory indicators of RA groups. Results : Compared with control group , TDO2 expression in RA group PBMC and synovial tissue significantly increased (P < 0. 001) ; TDO2 expression in RA group PBMC was positively correlated with erythrocyte sedimentation rate (ESR) ( r = 0. 405 , P = 0. 045) . Conclusion The expression of TDO2 is up⁃regulated in RA patients PBMC and synovial tissue , and positively correlates with inflammatory indicators ESR , suggesting that TDO2 may participate in RA disease progression.