A stable and reliable infected necrotizing pancreatitis (INP) model in rats was established in order to study the pathophysiological mechanism and pathological development rule of INP and explore the new therapeutic methods for the diseases. Forty-six SD rats were randomly divided into 5 groups. The animals in group A received the injection of 5% sodium taurocholate into the pancreatic duct and those in group B underwent that of E. coli into the pancreatic duct. The rats in groups C, D and E were subjected to the injection of 5% sodium taurocholate in combination with different concentrations of E. coli (103, 104, 105/mL, respectively) into the pancreatic duct. The dose of injection was 0.1 mL/100 g and the velocity of injection was 0.2 mL/min in all the 5 groups. Eight h after the injection, the survival rate of animals was recorded and the surviving rats were killed to determine the serum content of amylase and perform pathological examination and germ cultivation of the pancreatic tissue. The results showed that acute necrotizing pancreatitis model was induced by injection of 5% sodium taurocholate into the pancreatic duct. The positive rate of germ cultivation in group A was 12.5%. The acute necrotizing pancreatitis model was not induced by injection of E. coli into the pancreatic duct and the positive rate of germ cultivation in group B was 0. The INP model was established in groups C to E. The positive rate of germ cultivation was 60%, 100% and 100% and 8-h survival rate 100%, 100% and 70% in groups C, D and E, respectively. It was concluded that a stable and reliable model of INP was established by injection of 5% sodium taurocholate in combination with 104/mL E. coli into the pancreatic duct with a dose of 0.1 mL/100 g and a velocity of 0.2 mL/min. The pathogenesis of INP might be that the hemorrhage and necrosis of pancreatic tissue induced by sodium taurocholate results in weakness of pancreatic tissue in fighting against the germs. Meanwhile, the necrotic pancreatic tissue provides a good proliferative environment for the germs.
In order to evaluate the effect of mitofusin-2 gene (mfn2) on proliferation and chemotherapy sensitivity of human breast carcinoma cell line MCF-7 in vitro, pEGFPmfn2 plasmid carrying full length of mitofusin-2 gene was transfected, by using sofast, into MCF-7 cells. Mitofusin-2 gene expression in MCF-7 cells transfected by sofast after 48 h was detected by PCR and Western blotting, and the stable expression of GFP protein in MCF-7 cells by Western blot analysis. The proliferation of MCF-7 cells was assayed by MTT and cell counting. By using PI method, the effects of mfn2 on the cell cycle distribution of MCF-7 were measured. Annexin-V/PI double labeling method was employed to detect the changes in apoptosis induced by chemotherapeutics before and after transfection. The results showed that the MCF-7 cells transfected with mfn2 gene could stably and highly express GFP protein. MTT assay revealed that after transfection of mfn2 cDNA, the proliferation of MCF-7 cells was significantly inhibited. DNA histogram showed that cells arrested in S phase, and the percentage of S phase cells was 42.7, 17.2 and 19.6 in mfn2 cDNA transfection group, blank plasmid transfection group and blank control group, respectively (P<0.05). The apoptosis ratio of the cells transfected with mfn2 gene was increased from 3.56% to 15.95%, that of the cells treated with camptothecin (CAMP) followed by mfn2 gene transfection was 69.6%, and that in blank plasmid transfection group and blank control group was 31.0% and 23.4% respectively (P<0.05). It was suggested that transfection of mfn2 gene could significantly inhibit the proliferation of MCF-7 cells and promote their sensitivity to CAMP with a synergic effect.
The effect of cyclin-dependent kinase inhibitors Cip1/Waf1 (p21) on regulatory expression of survivin transcription in human hepatocellular carcinoma cell HepG2 was observed and the related mechanisms explored. Doxorubicin (DOX) was used to treat HepG2. Eukaryotic vector pEGFP-C2-p21 was transfected into HepG2 by lipofectamine and positive clones were screened out by G418. The mRNA expression of p21 and survivin was detected by real-time fluorescent quantitative polymerase chain reaction (RQ-PCR). Flow cytometry was used to examine the cell cycle, and reverse transcription polymerase chain reaction (RT-PCR) was used to measure the levels of E2F-1 and p300. The results showed that: (1) After treatment with DOX, the expression of p21 was increased, whereas that of survivin was reduced during 24 h of treatment; (2) After transfection of pEGFP-C2-p21 into HepG2, p21 level was significantly enhanced to 2100.11-folds or 980.89-folds in comparison to HepG2 or HepG2-C2 group, and survivin level was markedly down-regulated to 0.54% or 0.59% relative to the control groups; (3) Overexpressed p21 resulted in G1/G0 phase arrest (F=31.59, P<0.01), meanwhile E2F-1 mRNA and p300 mRNA were reduced as compared with those of controls (FE2F-1=125.28, P<0.05; Fp300=46.01, P<0.01). It was suggested that p21 could be a potential mediator of survivin suppression at transcription level in HepG2 cell, which might be through the block at G1/G0 phase and down-regulation of transcription factors E2F-1 and p300.
In this study, the expression of IL-24 at maternal-fetal interface and the roles in extravillous trophoblast (the TEV-1 cell line) invasion were examined. Immunohistochemistry was used to detect the expression of IL-24 in villi and decidual tissue. The proliferation of TEV-1 cells under the effect of IL-24 was measured by MTT assay. The invasiveness of TEV-1 cells under the effect of recombinant IL-24 (rhIL-24) was examined by transwell system. Immunohistochemical detection showed that IL-24 was expressed in the villi and decidual tissue, and distributed in villous column, trophoblasts, stroma and blood vessels. The proliferation of TEV-1 cells was not inhibited by rhIL-24 of various concentrations. The examination of invasion in vitro showed that rhIL-24 could inhibit the invasion of TEV-1 cells in a concentration-dependent manner. The results suggested IL-24 could inhibit the invasion of TEV-1 cells. Therefore, IL-24 produced by maternal-fetal interface in human first trimester pregnancy may influence the invasion of trophoblasts and is involved in normal pregnancy.