Objective To study the changes of hippocampal caspase-3 and PSD-95 expression levels in the mice exposed to ketamine 30 mg/(kg·d)for three months. Methods Forty C57BL/6 mice were randomly divided into two groups,and the chronic ketamine addiction model was established by giving mice a three month course of daily intraperitoneal injections of ketamine. Immunohistochemical study and Western blot-ting were applied to observe the expression of caspase-3 and PSD-95 protein. Results There were more expression of caspase-3 and less of PSD-95 in ketamine group as detected by immuohistochemistry. Western blotting results showed caspase-3 active fragment level significantly increased com-pared to saline group,but PSD-95 protein level was decreased. Conclusion The increased level of caspase-3 protein and reduced expression of PSD-95 are observed after long-term ketamine administration. These findings may provide an evidence for the neurotoxicity in mouse hippocampus of chronic ketamine addition as a recreational drug.

Objective To access the value of three dimensional gradient echo two-point Dixon water-fat separation sequence (3 D-DIXON) in quantitative diagnosis of non-alcoholic fatty liver disease(NAFLD) by comparing with in-phase/opposed-phase (IN/OPP)and proton magnetic resonance spectroscopy (1 H-MRS).Methods A total of 69 patients with NAFLD diagnosed by CT were divided into two groups by the ratio of liver spleen in CT (group A,low-grade fatty liver,n=32;group B,moderate and severe fatty liver,n=37).All patients underwent MR 3D-DIXION,1H MRS and IN/OPP examination twice within 1 week after CT examination.Fat fraction(FF) was evaluated and analyzed respectively.Results Pearson linear correlation analysis showed significant positive correlation between group A and group B about FF3D-DIXON,FFMRs and FFIN/OPP.Area under ROC curve (AUC) was different:AUCsYNTHESIZE＞AUCMRs＞AUCIN/OPP＞AUC3D-DIXON.Kruskal-Wallis H revealed significant difference among the three sequences no matter in group A or group B (P＜0.05).FF values of the three sequences (FF3D-DIXON,FFMRs and FFIN/OPP) were negatively correlated with CT liver/ spleen ratio in each group.The cut-off value of 3D-DIXON,IN/OPP and 1 H-MRS to diagnose presence or absence of fatty liver was 4.9 3 9 ％,5.2 8 4 ％ and 10.4 6 0 ％.Conclusion FF values measured by MRI methods might significantly vary based on different sequences.1 H-MRS is also the main method for quantitative assessment of fatty liver,3D-DIXON showed significant advantage in quantifying moderate and severe fatty liver.