重组小鼠干细胞逆转录病毒载体高效基因转染CD41+、UT7、U937和MDA-MB-435细胞

目的:研究重组小鼠干细胞逆转录病毒载体介导基因转染,探索一条高效基因转染的途径,为重组小鼠干细胞逆转录病毒载体在基因转染中的应用提供理论依据和奠定实验基础。方法:①逆转录病毒载体的构建:EC1-4(repeats1-4ofcadherin-5extracellulardomains)基因克隆产物和mutant(Ser222A)MEK1基因克隆产物,Bg1Ⅱ和EcoRⅠ限制性内切核酸酶切割后,克隆进入逆转录病毒表达载体pMSCV。②CD41⁺细胞的获取和细胞培养:从脐带血分离的CD34⁺细胞通过TPO诱导表达CD41,FACS分离CD41⁺细胞。高糖DMEM培养液培养NIH3T3和MDA-MB-435细胞,U937细胞培养在RPMI-1640培养液,UT7细胞是细胞因子依赖性细胞株,Iscove'smodifiedDulbeco's培养液中加入GM-CSF。③测定病毒滴度:逆转录病毒载体转入包装细胞293,36h后收集病毒上清液,感染NIH3T3细胞,流式细胞仪测定病毒滴度。④Westernblot:基因转染CD41⁺、UT7、U937和MDA-MB-435细胞,Westernblot检测基因产物的表达。结果:293细胞产生高滴度MEK1pMSCV病毒:3.1×10⁷,高滴度EC1-4pMSCV病毒:1.0×10⁸。用稀释8倍的病毒转染基因,重组逆转录病毒MEK1pMSCV转染白血病细胞株UT7和U973,GFP阳性细胞(转染阳性细胞)分别是60.73％、72.56％。重组逆转录病毒MEK1pMSCV转染原代培养细胞CD41⁺,GFP阳性细胞为30.57％。重组逆转录病毒EC1-4pMSCV转染人乳腺癌细胞株MDA-MB-435,GFP阳性细胞为97.54％。TPO作用CD41⁺和UT7细胞以及血清对U973细胞的作用,显示出外源mutationMEK基因的dominantnegative的效应,实验组磷酸化的MEK1减少。EC1-4基因转染的MDA-MB-435细胞表达了EC1-4基因产物。结论:重组小鼠干细胞逆转录病毒载体能高效基因转染CD41⁺、UT7、U937和MDA-MB-435细胞,转染的基因能稳定地表达。     

G-CSF对外周血树突状细胞亚群比例的影响

目的 :了解G CSF对小鼠外周血树突状细胞 (DC)亚群比例的影响。方法 :以不同剂量 (0、5 .0、10 .0或 15 .0 μg)的G CSF ,分别皮下注射于BALB/c小鼠 ,连续 6d ,每天 1次。第 6天分离外周血DC ,用流式细胞仪检测DC1(CD11c+ CD8a-)和DC2 (CD11c+ CD8a+ )的比例并计算其绝对值。结果 :经不同剂量的G CSF刺激后 ,外周血DC1的绝对值无显著变化 ,而DC2的绝对值增加 5倍 (9.6× 10 6/Lvs 5 5 .1× 10 6/L ,P <0 .0 1) ,DC1/DC2比值降低 (4.2vs 0 .7,P <0 .0 1)。结论 :G CSF在体内可提高外周血DC2的绝对数 ,对DC1的数无明显影响 ,从而使DC1/DC2的比例倒置     

Response of nasopharyngeal carcinoma cells to Epstein-Barr virus infection in vitro

Many nasopharyngeal carcinoma (NPC) biopsy specimens contain Epstein-Barr virus (EBV). However, the response of NPC cells to EBV infection in vitro and in vivo is not well characterized. In this experiment we infected NPC cells with EBV particles through endocytosis of a complex of EBV immunoglobulin A (IgA) secretory component (SC) protein to observe the response of host cells to the foreign viral infection in vitro. We found that EBV particles were endocytosed and stabilized in NPC nuclei 24 hours after infection; the EBV genomes were then gradually decreased after serial passages within 3 to 4 weeks by the following pathway: the EBV genomes first moved toward the nuclear envelope from the center of the nucleus; after crossing the nuclear envelope, they moved into the cytoplasm and toward the plasma membrane and were discharged by exocytosis. At the 10th day of EBV infection, EBV-latent membrane protein-1 and Epstein-Barr nuclear antigen (EBNA)-1 protein expressions could be detected, but not EBV-viral capsid antigen. Observation of EBNA-1 protein and host growth factor and cytokine gene expressions in the weeks after incubation revealed that the EBNA-1 protein expression was decreased proportionally with decrease of EBV genome. The mRNA expression of epithelial growth factor receptor, transforming growth factor (TGF)-alpha, interleukin (IL)-1beta, IL-6, and granulocyte-macrophage colony-stimulating factor increased within 1 to 2 weeks after infection, and gradually recovered to the original level at 3 to 4 weeks, whereas the mRNAs of TGFbeta1, TGFbeta receptor type I (TGFbetaRI), TGFbetaR type II, IL-8, and tumor necrosis factor-alpha remained unchanged. It is concluded that in vitro EBV infection in NPC cells results in increase of certain growth factor and cytokine gene expressions in host cells. The change in gene expression returns to the original level approximately 3 to 4 weeks after infection because of exocytosis of EBV DNA by the infected cells through an unidentified mechanism.     

Homologous recombination in the fission yeast Schizosaccharomyces pombe: different requirements for the rhp51+, rhp54+ and rad22+ genes

The Schizosaccharomyces pombe rhp51 ⁺ , rad22 ⁺ and rhp54 ⁺ genes are homologous to RAD51, RAD52 and RAD54 respectively, which are indispensable in the recombinational repair of double-strand breaks (DSBs) in Saccharomyces cerevisiae. The rhp51Δ and rhp54Δ strains are extremely sensitive to ionizing radiation; the rad22Δ mutant turned out to be much less sensitive. Homologous recombination in these mutants was studied by targeted integration at the leu1-32 locus. These experiments revealed that rhp51Δ and rhp54Δ are equally impaired in the integration of plasmid molecules (15-fold reduction), while integration in the rad22Δ mutant is only reduced by a factor of two. Blot-analysis demonstrated that the majority of the leu⁺ transformants of the wild-type and rad22Δ strains have integrated one or more copies of the vector. Gene conversion events were observed in less than 10% of the transformants. Interestingly, the relative contribution of gene conversion events is much higher in a rhp51Δ and a rhp54Δ background. Meiotic recombination is hardly affected in the rad22Δ mutant. The rhp51Δ and rhp54Δ strains also show minor deficiencies in this type of recombination. The viability of spores is 46% in the rad22Δ strain and 27% in the rhp54Δ strain, as compared with wild-type cells. However, in the rhp51Δ mutant the spore viability is only 1.7%, suggesting an essential role for Rhp51 in meiosis. The function of Rhp51 and Rhp54 in damage repair and recombination resembles the role of Rad51 and Rad54 in S. cerevisiae. Compared with Rad52 from S. cerevisiae, Rad22 has a much less prominent role in the recombinational repair pathway in S. pombe. Received: 20 July 1996     

Use of pulsed-field gel electrophoresis to investigate an outbreak of Serratia marcescens.

Pulsed-field gel electrophoresis (PFGE) typing was applied to the epidemiological investigation of 20 Serratia marcescens isolates collected from urine specimens of 17 patients and three urinals over a 2-month period. Twenty-five epidemiologically unrelated strains were also tested to determine the discriminatory power of PFGE. The PFGE fingerprints of each isolate were consistent in three different tests. The 20 outbreak isolates had an identical PFGE fingerprint pattern, while the epidemiologically unrelated strains demonstrated unique PFGE fingerprint patterns. The source of the outbreak was inadequately disinfected urinals. We conclude that PFGE served as a highly discriminatory and reproducible method for the epidemiological investigation of the outbreak of S. marcescens infection addressed by this study.     

人胎儿胃肠道P物质和胃动素的动态测定

用放射免疫方法测定了不同胎龄胎儿胃肠道Ｐ物质和胃动素的含量。结果发现Ｐ物质在第１０周胎儿胃肠道即可测及。以２６～３０周为最高。胃动素同样于第１０周胎儿胃肠道测及，而且也以２６～３０周含量最高。这说明含有Ｐ物质和胃动素的内分泌细胞和神经元及神经纤维以２６～３０周发育最快。     

Renal allograft rejection: induction and function of adhesion molecules on cultured epithelial cells.

The interaction of graft-infiltrating immune cells with donor parenchymal cells is an important early event in allograft rejection. This binding is stabilized by interaction of antigen-independent 'adhesion' molecules expressed on the two cell types. As the level of expression of these molecules can be altered during inflammation, a series of experiments was performed to examine the effects of the inflammatory cytokines interferon-gamma (IFN-gamma) and tumour necrosis factor-alpha (TNF-alpha) on adhesion molecules expressed by cultured human renal tubular epithelial cells. These cells constitutively expressed ICAM-1 and LFA-3. Incubation with IFN-gamma increased expression of ICAM-1 but had no significant effect on expression of LFA-3 (P greater than 0.05). Incubation with TNF-alpha increased expression of both ICAM-1 and LFA-3; IFN-gamma synergized with TNF-alpha to further augment expression of these molecules. Peripheral blood lymphocytes (PBL) showed an enhanced binding to allogeneic renal epithelial cell monolayers which had been pretreated with IFN-gamma or TNF-alpha. MoAbs specific for ICAM-1 or its ligand LFA-1 inhibited adhesion of PBL to either IFN-gamma- or TNF-alpha-pretreated renal cells. By contrast, antibodies specific for LFA-3 or its ligand CD2 only significantly blocked PBL adhesion to renal cells which had been pretreated with TNF-alpha. Combination of antibodies specific for multiple components of the adhesion systems produced greater inhibition of adhesion than was produced by any single MoAb. These results suggest that the inflammatory cytokines IFN-gamma and TNF-alpha up-regulate expression of functional ICAM-1 and LFA-3 molecules which can augment the binding of potentially graft-damaging lymphoid cells to renal tubular epithelial cells.     

干扰素诱导淋巴瘤细胞凋亡实验及临床研究

目的：分析梯度浓度的干扰素(IFN-α)对Burkitt淋巴瘤细胞株Daudi和T细胞淋巴瘤细胞株Jurkut及15例难治性淋巴瘤患者的直接作用。方法：以MTT法测定梯度浓度的IFN-α对两种淋巴瘤细胞株Daudi、Jurkat增殖作用的影响，以DNA末端标记法，流式细胞术，电镜观察测定IFN-α对淋巴瘤细胞的凋亡诱导作用，并采用瘤内注射IFN-α联合化疗治疗15例耐药的难治性淋巴瘤。结果：低浓度亚IFN-α对DaudiJurkat细胞增殖无明显抑制作用，高浓度IFN(10000U／ml)可显著抑制两种细胞增殖，且有时间相关性。高浓度的IFN-α可诱导淋巴瘤细胞凋亡。15例患者CR5例，PR7例，有效率80％，无明显毒副作用。结论：IFN-α可抑制淋巴瘤细胞增殖，诱导凋亡，有显著时间，剂量依赖性。局部应用IFN-α联合化疗是治疗难治性淋巴瘤的有效方法之一。