Avian pathogenic Escherichia coli MT78 invades chicken fibroblasts

Avian pathogenic Escherichia coli (APEC) are responsible for extraintestinal diseases, called colibacillosis, in avian species. The most severe manifestation of the disease is colisepticemia that usually starts at the respiratory tract and may result in bird death. However, it is not yet clear how APEC cross the respiratory epithelium and get into the bloodstream. In this work, we studied the interaction between 8 APEC strains (UEL31, UEL17, UEL13, UEL29, MT78, IMT5155, IMT2470, A2363) and a chicken non-phagocytic cell, the fibroblast CEC-32 cell line. We investigated the association profile, the invasion capability, the cytotoxicity effect and the induction of caspase-3/7 activation in an attempt to understand the way the pathogen gains access to the host bloodstream. Association to cells was determined after 1 h of infection, while cell invasion was determined after 4 and 24 h of infection. The cytotoxic effect of bacterial infection was measured by lactate dehydrogenase (LDH) release and the activation of the apoptotic program was verified by caspase-3/7 activation. Also, the presence of genes for adhesins, invasins and other related virulence-associated factors was verified by PCR. All bacterial strains showed similarity in relation to adhesion, LDH release and caspase-3/7 activation. However, one APEC strain, MT78, showed high invasion capability, comparable to the invasive Salmonella typhimurium strain SL1344. Since an APEC strain was capable of invading non-phagocytic cells in vitro, the same may be happening with the epithelial cells of the avian respiratory tract in vivo. CEC-32 monolayers can also provide a useful experimental model to study the molecular mechanisms used by APEC to invade non-phagocytic cells.     

水田泥浆对农用纸膜黏附性影响的试验研究

为探索提高农用纸膜与水田泥浆的贴合质量的方法,试验研究了水田泥浆含水率、纸膜承载正压力和加载速度等因素对泥浆纸膜间黏附力的影响规律,建立了相应的数学模型。试验结果表明,泥浆含水率为34.5%～35.5%时,随含水率增加,泥浆黏度、黏附力急剧下降;含水率超过35.5%时,含水率变化对黏度、黏附力影响不显著;黏附力随泥浆黏度的增加呈对数增长趋势。纸膜与泥浆间的黏附力随正压力的增加,呈线性增加趋势。加载速度在0.83×10-3～0.5×10-2 m/s区间,黏附力随加载速度增加而快速上升;加载速度超过0.5×10-2 m/s时,黏附力上升速度较慢;加载速度在0.67×10-2～0.83×10-2 m/s范围内时,黏附力趋于定值。因此,为了提高纸膜覆盖质量,整地、泡田过程中,应使土壤含水率最大不要超过饱和含水率的1.05倍;在满足泥浆的抗压强度的前提下应增加纸膜单位面积上的正压力;覆膜速度低于0.5×10-2 m/s时,通过加载速度的方法来提高覆膜质量。研究成果将为纸膜覆膜机构的设计提供参考。     

中国荷斯坦种公牛BLAD遗传缺陷的分子检测及系谱分析

本试验运用限制性片段长度多态性聚合酶链式反应（RFLP-PCR）方法,检测我国荷斯坦种公牛白细胞粘附缺陷（bovine leukocyte adhesion deficiency,BLAD）基因的携带频率。共检测了来自全国14个公牛站的587头种公牛,发现BLAD携带者8头,携带率为1.36%。对现有公牛系谱信息分析显示,携带者公牛来自美国、加拿大和中国,其中6头携带者公牛可以追溯到共同祖先Osborndale Ivanhoe。此外,本研究还对我国荷斯坦牛遗传缺陷的控制和携带者公牛的利用提出建议。     

粘附分子CD44v6在宫颈癌组织中的表达及意义

目的:了解粘附分子CD44v6在宫颈癌组织中的表达及其意义。方法:采用免疫组织化学法(SP法)检测CD44v6在69例宫颈癌组织及20例正常宫颈组织中的表达。结果:正常宫颈组织中的CD44v6呈阴性表达。69例宫颈癌组织中CD44v6的阳性表达率为68.1％(47/69)。CD44v6的阳性表达在不同的病灶大小、临床分期、细胞分化程度及有无淋巴结转移的宫颈癌组织中差异有统计学意义(P<0.05～0.01);在不同的病理类型及年龄的患者中差异无统计学意义(P>0.05)。结论;CD44V6可能在宫颈癌的生长、浸润及转移过程中起重要作用,可望作为反映宫颈癌恶性潜能的新指标。     

爬山虎及川鄂爬山虎吸盘壁面附着机制的形态研究

对城镇建筑物壁面绿化中常见的爬山虎及川鄂爬山虎吸盘壁面附着机制进行研究，发现卷须顶端部分的表皮细胞在卷须从枝节发生后（长度不到１０ｍｍ）即开始膨大，随卷须伸长而充分膨大并富含粘性物质。卷须接触壁面时，通过粘性物质粘着于壁面，或以钩状弯曲攀附于壁面微小突起或突入微小的穴中。粘性物质的增多及沿接触面的扩展，使吸盘与壁面密着。卷须通过粘液的硬化、吸盘的干枯、顶端的指状细胞或组织突入微小凹穴，以及吸盘接触面与壁面之间形成的封闭空间的吸着等机制的综合作用，才得以牢固而持久地附着于壁面。     

动物腹腔手术后粘连的成因及防制概述

就术后粘连发生的诱因、发生机理进行了阐述,并结合动物粘连模型的试验研究结果及临床研究结果,对预防腹腔手术后粘连的药物和方法进行了综述。     

ROS promotes adhesion of neutrophils to bone marrow stromal cells and its mechanism

AIM:To investigate the effect of reactive oxygen species (ROS) on the adhesion of neutrophils to bone marrow stromal cells (BMSCs) and its mechanism. METHODS:Murine bone marrow neutrophils were isolated from mouse tibia and femur by density gradient centrifugation. HL60 cells were induced into human mature neutrophils (dHL60 cells) by DMSO treatment. Murine bone marrow neutrophils and dHL60 cells were labeled with CFDA-SE. The adhesion of the CFDA-SE-labeled cells to BMSC monolayer was tested by microplate reader after H₂O₂ treatment. The level of glutaredoxin 1 (Grx1) in dHL60 cells infected by lentivirus carrying Grx1 expression vector was examined by fluorescence microscopy and Western blot. The genotype of Grx1^-/- mice was identified by PCR. RESULTS:Diff-Quick staining result displayed that the purity of murine bone marrow neutrophil was higher than 90%. The adhesion of H₂O₂-pretreated neutrophils to BMSCs was higher than that of the control cells (P<0.01). The expression of Grx1 in Grx1 stably transfected dHL60 cells was significantly higher than that in the control cells. After H₂O₂ treatment, the results of in vitro adhesion assay showed that the adhesion of dHL60 cells with Grx1 over-expression to BMSCs was lower than that of the control cells (P<0.01). The results of PCR showed no Grx1 was detected at the whole gene level in Grx1^-/- mice. Compared with the neutrophils from wild-type mice, the neutrophils from Grx1^-/- mice displayed increased adhesion to BMSCs after H₂O₂ treatment. Vascular cell adhesion molecule-1 (VCAM-1) antibody pretreatment induced the adhesion rate back to non-H₂O₂-treated condition. CONCLUSION:ROS promotes the adhesion of neutrophils to BMSCs in bone marrow, which might be regulated by VCAM-1 adhesion signaling-related S-glutathionylation.     

The expression of plasmid mediated afimbrial adhesin genes in an avian septicemic Escherichia coli strain

An Escherichia coli strain (SEPT13) isolated from the liver of a hen presenting clinical signs of septicaemia had a LD₅₀ of 4.0 × 10⁵ CFU/ml in one-day-old chickens, expressed Ia, Ib, E1, E3, K and B colicins and aerobactin. The strain was ampicillin and streptomycin resistant, and found to have fimA, csgA and tsh DNA related sequences; it could adhere to and invade HEp-2 and tracheal epithelial cells, expressed fimbriae (observed by electron microscopy), and had five plasmids of 2.7, 4.7, 43, 56, and 88 MDa. Transposon mutagenesis of strain SEPT13, with transposon TnphoA, resulted in a mutant strain named ST16 that had a LD₅₀ of 1.2 × 10¹² CFU/ml. All other biological characteristics of strain ST16 were the same as those detected for strain SEPT13 except for the migration of an 88 MDa plasmid to the 93 MDa position indicating the insertion of the transposon into the 88 MDa plasmid. The 93 MDa plasmid of strain ST16 was transferred, by electroporation assay, to non-pathogenic receptor strains (E. coli strains K12 MS101 and HB101), resulting in transformant strains A and B, respectively. These strains exhibited adhesion properties to in vitro cultivated HEp-2 cells but did not have the capacity for invasion. The adherence occurred despite the absence of fimbriae; this finding suggests that the 88 MDa plasmid has afimbrial adhesin genes.     

不同功能性寡糖对细菌增殖与黏附性影响

本试验旨在研究不同功能性寡糖对乳酸杆菌、大肠杆菌和沙门氏菌增殖的影响及大肠杆菌、沙门氏菌对猪空肠上皮细胞(IPEC-J2)黏附性的影响。试验用8种功能性寡糖以0.25%的添加量分别增殖干酪乳杆菌、植物乳杆菌、大肠杆菌和沙门氏菌,测定其对增殖的影响;并以IPEC-J2作为体外模型,通过菌落计数的方法,研究不同功能性寡糖对大肠杆菌、沙门氏菌黏附IPEC-J2的影响。结果表明:1) 8种功能性寡糖对细菌的增殖作用有差异,果寡糖对有益菌的增殖效果最显著,且对有害菌增殖效果最低并有一定抑制生长的趋势。2) 8种功能性寡糖均能显著降低大肠杆菌和沙门氏菌对IPEC-J2的黏附性(P<0.05),其中甘露寡糖对沙门氏菌的黏附抑制作用最好,果寡糖则对大肠杆菌黏附抑制作用最明显。由此可见,在本试验条件下,功能性寡糖不仅能够促进有益菌大量增殖,而且对有害菌增殖也有一定促进作用,且不同功能性寡糖对细菌的促进作用差异显著; 8种功能性寡糖能够显著抑制大肠杆菌、沙门氏菌对肠道上皮细胞黏附的作用。     

玉米赤霉烯酮对趋化因子诱导的小鼠T细胞迁移效应和黏附与迁移相关蛋白表达的影响

为揭示玉米赤霉烯酮(ZEA)免疫毒性机理,通过体外试验研究了ZEA对趋化因子诱导的小鼠T细胞迁移效应的影响,以及这一过程中与细胞黏附与迁移相关蛋白的变化。以ConA作为T细胞活化剂,以不同浓度ZEA(0、10、20、40μmol/L)染毒处理细胞后,Transwell法检测T细胞分别在CCL19、CCL21作用下的迁移效应,以及利用流式细胞术检测迁移后CD4、CD8阳性T细胞所占比例。激光共聚焦显微镜拍摄细胞穿膜形态,Western blot检测T细胞迁移及细胞黏附相关蛋白的表达。结果显示,ZEA可以分别降低CCL19和CCL21趋化的T细胞的迁移指数并扰乱迁移后CD4、CD8阳性T细胞之间的比例。此外,ZEA可以不同程度地抑制CCL19和CCL21介导的T细胞穿膜效应。Western blot结果显示,20、40μmol/L的ZEA作用可下调T细胞迁移及细胞黏附相关蛋白的表达。结果表明,ZEA可以抑制趋化因子介导的T细胞迁移效应,在这一过程中,黏附蛋白及迁移蛋白的表达均受到抑制,提示ZEA可能通过抑制T细胞运动过程中黏附及迁移这两个环节,进而影响T细胞的免疫应答,从而发挥免疫抑制作用。