单增李斯特菌inl A/ inl B双基因缺失株生长特性观察及对小鼠致病性研究

目的探究单增李斯特菌inl A/inl B双基因缺失株的生物学特性。方法通过体外胁迫培养条件下OD600测定以及小鼠感染试验,对Lm 90-△inlAB和Lm 90的抗胁迫能力及细菌致病力进行研究。结果低温(4 ℃、30 ℃)环境下,Lm 90和Lm 90-△inlAB生长差异无统计学意义(t4 ℃=0.057,P>0.05;t30 ℃=0.441,P>0.05),适温37 ℃及42 ℃高温环境下,Lm 90-△inlAB较Lm 90生长受到抑制,生长差异具有统计学意义(t37 ℃=0.763,P<0.05;t42 ℃=1.147, P<0.05);体外耐酸碱试验中,Lm 90-△inlAB耐酸性未明显改变,而耐碱能力强于亲本株Lm 90,生长差异具有统计学意义(pH=9时t=2.837,P<0.05);在含有3.5%酒精的BHI培养基及含5% NaCl高渗BHI培养基中,Lm 90-△inlAB增长趋势明显低于Lm 90,生长差异具有统计学意义(t酒精=1.422,P<0.05;tNaCl=1.382,P<0.05),Lm 90-△inlAB对酒精及高盐的耐受力显著低于Lm 90;小鼠毒力测定结果表明,Lm 90-△inlAB与Lm 90半数致死量分别为106.94CFU、105.68CFU,Lm 90-△inlAB毒力下降明显,在不同检测时间点Lm 90-△inlAB在小鼠肝脏和脾脏内的载菌量均少于Lm 90,载菌量差异具有统计学意义(t肝=2.454,P<0.05;t脾=2.443,P<0.05)。结论　Lm的抗胁迫能力可能随着基因的缺失发生显著改变,内化素InlA/InlB与单增李斯特菌侵染宿主的能力有一定的调控作用。缺失株生物学特性测定对研究Lm胁迫环境生存及毒力因子的致病机理提供了科学依据。     

血脂康对载脂蛋白E基因敲除小鼠肝细胞内Ca2+及线粒体膜电位的影响

目的观察血脂康胶囊对载脂蛋白E基因敲除小鼠肝细胞内Ca2 浓度及线粒体膜电位的影响。方法采用胶原酶消化法分离载脂蛋白E基因敲除小鼠肝细胞,体外原代培养8天后,加入含10%血脂康血清的培养基,48 h后以Flou-3/AM和JC-1为探针,应用激光共聚焦显微镜测量肝细胞内Ca2 浓度和线粒体膜电位。结果血脂康可明显降低载脂蛋白E基因敲除小鼠肝细胞内Ca2 浓度,与对照组比较差异有显著性(P<0.01);同时,血脂康可明显提高载脂蛋白E基因敲除小鼠肝细胞线粒体膜电位(P<0.05)。结论血脂康可降低载脂蛋白E基因敲除小鼠肝细胞内Ca2 浓度,提高线粒体膜电位,这可能是血脂康对抗高脂血症发生和发展的重要机制之一。     

硒和锌对细胞氧化低密度脂蛋白作用的影响

为探讨微量元素硒和锌在体内抗低密度脂蛋白氧化的作用及其可能机制,采用硫代巴比妥酸法测定大鼠动脉平滑肌细胞对低密度脂蛋白的氧化反应,采用噻唑蓝法了解动脉平滑肌细胞增殖及邻联二茴香胺底物反应的方法测髓过氧化物酶活性。结果表明１０μｍｏｌ／Ｌ亚硒酸钠显著减少了丙二醛的生成,而相同浓度的硫酸锌效应不明显,但二者均可见动脉平滑肌细胞增殖减少。此外,低密度脂蛋白诱导动脉平滑肌细胞的髓过氧化物酶活性显著升高,但１０μｍｏｌ／Ｌ亚硒酸钠似乎不能抑制这种效应。揭示硒与锌均抑制氧化型低密度脂蛋白促动脉平滑肌细胞的增殖作用,前者与抗低密度脂蛋白氧化有关,且可能发生在髓过氧化物酶催化形成的酷酰基自由基之后的某个环节,后者尚待进一步探讨。     

姜黄素对实验性肝纤维化大鼠肝脏bax和bcl-2表达的影响

[目的]探讨姜黄素(curcumin,CUR)对大鼠肝纤维化的防治作用及对肝组织bax和bcl-2蛋白及基因表达的影响.[方法]建立CCl4致大鼠实验性肝纤维化模型.用免疫组化法比较正常组、模型组以及CUR组的bcl2、bax蛋白的表达,用RT-PCR法比较各组肝组织bcb-2、bax mRNA的表达.[结果]CUR组肝组织炎症和纤维化程度较模型组显著减轻.bax蛋白主要表达在肝细胞质,而纤维间隔及汇管区呈低表达;beb-2主要表达在纤维间隔及汇管区.bax及bcl-2在模型组及CUR组表达均高于正常组(P<0.01),CUR组均较模型组降低(P<0.01).bax及bcI-2 mRNA在模型组及CUR组表达比正常组增高(P<0.01,<0.05),CUR组均较模型组降低(P<0.05).[结论]CUR可能通过降低肝细胞表达bax、减少肝细胞凋亡而减轻肝脏损伤,通过降低bcl-2表达、诱导肝星状细胞凋亡发挥减轻肝纤维化的作用,防治大鼠肝纤维化.     

Altered frequency of a promoter polymorphism of the kinin B2 receptor gene in hypertensive African-Americans

Components of the kallikrein kinin system have been associated with the pathophysiology of hypertension in animal and human studies. In this study, we examined the distribution of four different polymorphisms of the kinin B₁ and B₂ receptor genes in a population of 120 normotensive and 77 hypertensive African-Americans. Allelic frequencies for three of the four polymorphisms were significantly different from those previously reported in Caucasian populations. Among the polymorphisms analyzed, a potentially functionally significant polymorphism in the core promoter of the kinin B₂ receptor (C⁻⁵⁸→T transition) displayed an increased prevalence of the C⁻⁵⁸ allele in the hypertensive patients as compared with the controls (0.75 v 0.62, P = .009). Thus, this B₂ receptor promoter polymorphism may represent a susceptibility marker for essential hypertension in African-Americans.     

Hsp90 inhibitors cause G2/M arrest associated with the reduction of Cdc25C and Cdc2 in lung cancer cell lines

Purpose: Hsp90, a molecular chaperone, is involved in folding, assembly, maturation, and stabilization of the client proteins which regulate survival of cancer cells, and thus Hsp90 inhibitors may be potential molecular targeting agents for cancer treatment. We investigated whether Hsp90 inhibitors have therapeutic value in lung cancer. Methods: First, expression levels of Hsp90 in lung cancer cells were examined by western blotting and immunohistochemical analyses. Next, the effect of Hsp90 inhibitors, geldanamycin and 17-allylaminogeldanamycin (17-AAG), on lung cancer cell growth was examined. Results: Remarkable high expression of Hsp90 protein in lung cancer cell lines and a more intense signal for Hsp90 by immunohistochemistry in males, patients with smoking index over 600, and squamous cell carcinoma were observed. Both Hsp90 inhibitors dose dependently inhibited the growth of lung cancer cell lines and induced G2/M arrest concomitant with decreased protein levels of Cdc25C and Cdc2. Moreover, combination of an Hsp90 inhibitor and irradiation had an additive effect on cell growth inhibition and reduction of Cdc25C and Cdc2 protein levels. Conclusion: Hsp90 inhibitor is thus a therapeutic tool for lung cancer based on its target proteins, which are involved in tumor progression and antiproliferative activity in lung cancer cells.     

Moderate heart dysfunction in mice with inducible cardiomyocyte-specific excision of the Serca2 gene

The sarco(endo)plasmic reticulum calcium ATPase 2 (SERCA2) transports Ca²⁺ from cytosol into the sarcoplasmic reticulum (SR) of cardiomyocytes, thereby maintaining the store of releasable Ca²⁺ necessary for contraction. Reduced SERCA function has been linked to heart failure, and loss of SERCA2 in the adult mammalian heart would be expected to cause immediate severe myocardial contractile dysfunction and death. We investigated heart function in adult mice with an inducible cardiomyocyte-specific excision of the Atp2a2 (Serca2) gene (SERCA2 KO). Seven weeks after induction of Serca2 gene excision, the mice displayed a substantial reduction in diastolic function with a 5-fold increase in the time constant of isovolumetric pressure decay (tau). However, already at 4 weeks following gene excision less than 5% SERCA2 protein was found in myocardial tissue. Surprisingly, heart function was only moderately impaired at this time point. Tissue Doppler imaging showed slightly reduced peak systolic tissue velocity and a less than 2-fold increase in tau was observed. The SR Ca²⁺ content was dramatically reduced in cardiomyocytes from 4-week SERCA2 KO mice, and Ca²⁺ transients were predominantly generated by enhanced Ca²⁺ flux through L-type Ca²⁺ channels and the Na⁺-Ca²⁺ exchanger. Moreover, equivalent increases in cytosolic [Ca²⁺] in control and SERCA2 KO myocytes induced greater cell shortening in SERCA2 KO, suggesting enhanced myofilament responsiveness. Our data demonstrate that SR-independent Ca²⁺ transport mechanisms temporarily can prevent major cardiac dysfunction despite a major reduction of SERCA2 in cardiomyocytes.     

原花青素B2对LPS诱导的心肌细胞损伤的保护作用及机制

目的 探讨原花青素B₂(PCB₂)对LPS诱导的心肌细胞损伤的保护作用及机制。方法 正常培养心肌细胞H9c2,用LPS诱导H9c2细胞建立细胞损伤模型,分别用6.25、12.5、25.0 μmol/L的PCB₂处理模型细胞,25.0 μmol/L的PCB₂处理模型细胞后加入核因子κB(NF-κB)信号通路抑制剂PDTC处理。采用MTT法检测细胞存活率;流式细胞术检测细胞凋亡率;酶联免疫吸附法(ELISA)检测细胞肿瘤坏死因子α(TNF-α)、白细胞介素1β(IL-1β)和白细胞介素6(IL-6)的水平;丙二醛(MDA)、超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)试剂盒分别检测MDA含量和SOD、GSH-Px活性;Westem blot检测细胞中NF-κB、IκB-α蛋白表达。结果 LPS组细胞存活率较对照组显著降低(P＜0.05),而PCB₂显著升高细胞存活率(P＜0.05)。LPS组细胞凋亡率较对照组显著升高(P＜0.05),而PCB₂显著降低LPS处理的细胞凋亡率(P＜0.05)。LPS组细胞TNF-α、IL-1β、IL-6水平较对照组显著升高(P＜0.05),而PCB₂显著降低LPS处理细胞TNF-α、IL-1β、IL-6水平(P＜0.05)。与对照组比较,LPS组细胞MDA含量显著升高,SOD、GSH-Px活性显著降低(P＜0.05);PCB₂显著降低LPS处理的细胞MDA含量,显著升高SOD、GSH-Px活性(P＜0.05)。与对照组比较,LPS组细胞NF-κB蛋白表达显著升高,IκB-α蛋白表达显著降低(P＜0.05);与LPS组比较,PCB₂显著降低细胞NF-κB蛋白表达,显著升高IκB-α蛋白表达(P＜0.05)。与LPS+PCB₂组相比,LPS+PCB₂₊PDTC能显著降低细胞凋亡率和TNF-α、IL-1β、IL-6、MDA含量,显著升高SOD、GSH-Px活性。结论 PCB₂降低LPS诱导的心肌细胞凋亡率、炎症水平和氧化应激,提高细胞存活率,这可能与抑制NF-κB信号通路的活化有关。     

广东省猪链球菌2型菌株毒力基因及分子分型分析

目的 掌握广东地区猪链球菌2型菌株毒力因子及分子分型情况,为诊断、治疗和制定防控措施提供科学依据。方法 选取荚膜多糖(cps2J)、溶菌酶释放蛋白(mrp)、溶血素(sly)、谷氨酸脱氢酶(gdh)、胞外因子(ef)等5个猪链球菌2 型主要毒力基因,分别设计引物对分离自病人、病猪的22株猪链球菌2 型菌株进行PCR检测,并对菌株进行MLST分型分析。结果 22株菌分为5种毒力基因型,其中cps2J+/mrp+/sly+/gdh+/ef+型别为病人及病猪菌株所共有,cps2J+/mrp+/sly-/gdh-/ef+、cps2J+/mrp+/sly-/gdh+/ef+为病人菌株所特有,cps2J+/mrp-/sly+/gdh+/ef+、cps2J+/mrp-/sly-/gdh+/ef-为病猪菌株所特有;MLST分型结果显示,22株分为ST1、ST7和ST28三个型别,其中ST1、ST7型为病人和病猪菌株所共有,均同属于ST1克隆复合物,ST28型为病猪所特有。结论 广东地区病人、病猪的猪链球菌2 型菌株毒力基因型及MLST分子分型均呈现多样化,且部分型别为两者所共有,为阐明猪传染给人提供了直接的证据。     

三带喙库蚊胸腔接种乙型脑炎减毒活疫苗病毒的感染动态及致病力观察

目的通过蚊虫胸腔接种乙脑病毒减毒活疫苗SA14-14-2株,了解该疫苗病毒在蚊虫体内的繁殖情况及其毒力稳定性,进一步评价该疫苗的安全性。方法建立三带喙库蚊的实验室种群,用SA14-14-2、SA14和中山株胸腔接种三带喙库蚊,感染后不同时间取一定数量的蚊虫,研磨制成悬液,用空斑试验检测蚊虫体内的病毒滴度。用感染蚊悬液接种乳鼠和感染蚊虫直接叮咬乳鼠的方法,观察对乳鼠的致病性。结果SA14-14-2、SA14和中山株病毒感染蚊虫后,第2~20d蚊虫体内均能检测到病毒,其中SA14-14-2株的滴度为2~3.72 logPFU/ml,SA14株为3~4.85 logPFU/ml,中山株为3~5.40 log-PFU/ml。中山株的感染滴度最高,其次是SA14株,SA14-14-2株的感染滴度最低,表明蚊虫对野毒株(中山株和SA14株)更为敏感。感染SA14-14-2病毒的三带喙库蚊悬液接种乳鼠,未能引起乳鼠发病或死亡。感染SA14-14-2病毒的三带喙库蚊叮咬乳鼠,未见乳鼠发病或死亡,也未从小白鼠血清中检测到乙脑病毒抗体。结论经胸腔接种,SA14-14-2病毒能在三带喙库蚊体内稳定繁殖。动物接种和蚊虫叮咬试验表明,经蚊体内繁殖的SA14-14-2病毒毒力仍保持原有的弱毒特性,表明该减毒活疫苗通过蚊虫体内繁殖后不会造成传播。     

PGE2对气道平滑肌细胞分泌和凋亡影响的研究

目的前列腺素E2（prostaglandin E2,PGE2）通过调控气道平滑肌细胞（airway smooth muscle cells,ASMCs）的迁移、分泌、增殖功能,对哮喘气道重塑有关键性影响。研究PGE2对ASMCs凋亡及其分泌白介素4（interleukin 4,IL-4）、白介素10（interleukin 10,IL-10）和γ-干扰素（interferon-γ,IFN-γ）的影响,对阐明PGE2通过调控ASMCs分泌Th1/Th2细胞因子对气道炎症发挥作用机制有重要意义。方法用大鼠气道平滑肌细胞株与终浓度为10-9～10-6的PGE2共培养24h,分6组,共4个浓度梯度。用AnnexinV-EGFP/PI双染细胞凋亡检测试剂盒在流式细胞仪测定凋亡率,同时用IL-4、IL-10和IFN-γELISA试剂盒在酶标仪检测其浓度。每4个复孔为1组,实验重复2次,数据为8孔的平均值。结果应用不同浓度的PGE2后ASMCs各组细胞凋亡率与对照组相比无明显变化。但IL分泌与PGE2有显著的量效关系,IL-4和IL-10随PGE2浓度下降而分泌量显著下降,但IFN-γ随PGE2浓度下降而分泌量呈升高趋势,两者呈分离现象（空白对照、阴性对照、10-9PGE2、10-8PGE2、10-7PGE2、10-6PGE2组,IL-4分别为6.77±1.58、9.24±2.45、38.17±11.33、29.27±11.12、26.05±9.49、21.11±7.21;IL-10为4.8±1.06、6.35±2.11、71.89±12.03、43.68±11.25、28.89±8.75、24.31±6.67;IFN-γ为2.17±1.97、3.25±1.48、10.63±4.75、13.4±5.57、15.47±6.16、19.54±6.35）。结论 PGE2能调控ASMCs分泌细胞因子,随着浓度梯度增加能促进Th1型细胞因子IFN-γ分泌,同时抑制Th2型细胞因子IL-4、IL-10分泌,但对ASMCs凋亡无显著影响。认为在正常状态下PGE2的分泌与维持气道内Th1/Th2的平衡有关。