钠/钙交换蛋白SLC24A6在实验性颅内出血导致脑损伤过程中的作用及机制研究

目的探究钾依赖钠/钙交换蛋白-6(SLC24A6)参与大鼠脑出血后继发性脑损伤的作用和可能机制。方法建立SD大鼠脑出血模型,检测大鼠脑出血后尾状核SLC24A6表达及其介导的细胞内钙浓度([Ca^(2+)]_i)随时间变化的情况,观察SLC24A6在正常氧浓度和低氧条件下对[Ca^(2+)]_i的调控。结果脑出血早期,尾状核SLC24A6蛋白和SLC24A6mRNA水平均降低,在脑出血后3 d降至最低水平,5和7 d后轻微升高。脑出血后早期,[Ca^(2+)]_i增加,于脑出血后3 d达最高水平,5和7 d时逐步下降。正常氧浓度下,转染SLC24A6导致HEK293[Ca^(2+)]_i升高。结论 SLC24A6通过抑制钙超载在脑出血后脑损伤中起保护作用。

三(2-氯乙基)磷酸酯诱导肝细胞线粒体毒性的研究

[目的]研究三(2-氯乙基)磷酸酯[tris(2-chloroethyl)phosphate,TCEP]对肝细胞线粒体功能的影响。[方法]用0.00(溶剂对照组)、3.12、12.50、50.00和200.00 mg/L TCEP分别处理人正常肝细胞(L02细胞)和人肝癌细胞(Hep G2细胞)24 h和48 h。测定细胞活力、线粒体内活性氧水平、线粒体DNA拷贝数、线粒体膜电位和胞内游离钙(Ca2+)水平以及胞内ATP的浓度。[结果]与相应溶剂对照组相比,在24 h,200.00 mg/L TCEP处理组L02细胞活力降低(P<0.05),≥12.50 mg/L TCEP处理组Hep G2细胞活力降低(P<0.05);在48 h,50.00 mg/L和200.00 mg/L TCEP处理组两种细胞活力降低(P<0.05)。所有TCEP处理组两种细胞的线粒体DNA拷贝数均减少(P<0.05或P<0.01)。在24 h,所有TCEP处理组两种细胞的线粒体膜电位均下降(P<0.05或P<0.01)。在24 h,200.00 mg/L TCEP处理组两种细胞胞内游离Ca2+水平均升高(P<0.01);在48 h,50.00 mg/L和200.00 mg/L TCEP处理组两种细胞胞内游离Ca2+均升高(P<0.01)。在24 h和48 h,200.00 mg/L TCEP处理组L02胞内ATP水平降低(P<0.05);在24 h,50.00 mg/L和200.00 mg/L TCEP处理组Hep G2胞内ATP浓度下降(P<0.05或P<0.01)。[结论]一定浓度的TCEP可致肝细胞线粒体损伤和线粒体功能指标异常,提示TCEP有肝细胞线粒体毒性。

Screening and identification of Shigella flexneri 2a virulence-related genes induced after invasion of epithelial cells

An in vivo expression technology (IVET) was applied to screen s.flexneri 2a genes induced after invasion of epithelial cells, and virulence-related genes were further identified by mutational analysis. Thirteen intracellular induced genes were identified with a HeLa cell infection model. Of these, two were identified as alkylation-related genes; one was related to metabolism; one encoded a transcriptional regulator; three were identified as insertion elements; three ap- peared to be antisense to genes involved in the transmethylation,biosyntheseis, and phos- photransferase system;and three were predicted to encode polypeptides with unknown functions. Intracellular survival assavs showed that the mutants of alkA,citC and wcaJ genes had lower capability of intracellular replication or survival than the the wild-type strain.The results indicated that alkA, citC and wcaJ genes could take part in the intracellular survival or replication of S. flexneri 2a and the capability of intracellular survival or replication could be one of the major virulence elements. However, the yaiC mutant was able to survive in the murine infection assay but almost not in HeLa cell infection assay. Very possibly, yaiC gene was involved in the other mechanism of S. flexneri virulence. This study might lead to a better understanding of the intra- cellular survival or proliferation process of S. flexneri 2a and perhaps provide insights into the pathogenicity of this pathogen.