Role of the Protective Antigen Octamer in the Molecular Mechanism of Anthrax Lethal Toxin Stabilization in Plasma

Anthrax is caused by strains of Bacillus anthracis that produce two key virulence factors, anthrax toxin (Atx) and a poly-γ-D-glutamic acid capsule. Atx is comprised of three proteins: protective antigen (PA) and two enzymes, lethal factor (LF) and edema factor (EF). To disrupt cell function, these components must assemble into holotoxin complexes, which contain either a ring-shaped homooctameric or homoheptameric PA oligomer bound to multiple copies of LF and/or EF, producing lethal toxin (LT), edema toxin, or mixtures thereof. Once a host cell endocytoses these complexes, PA converts into a membrane-inserted channel that translocates LF and EF into the cytosol. LT can assemble on host cell surfaces or extracellularly in plasma. We show that, under physiological conditions in bovine plasma, LT complexes containing heptameric PA aggregate and inactivate more readily than LT complexes containing octameric PA. LT complexes containing octameric PA possess enhanced stability, channel-forming activity, and macrophage cytotoxicity relative to those containing heptameric PA. Under physiological conditions, multiple biophysical probes reveal that heptameric PA can prematurely adopt the channel conformation, but octameric PA complexes remain in their soluble prechannel configuration, which allows them to resist aggregation and inactivation. We conclude that PA may form an octameric oligomeric state as a means to produce a more stable and active LT complex that could circulate freely in the blood.     

Adaptation of signature-tagged mutagenesis to Escherichia coli K1 and the infant-rat model of invasive disease

With the exception of the polysialic acid capsule (K1 antigen), little is known about other virulence factors needed for systemic infection by Escherichia coli K1, the leading cause of Gram-negative neonatal meningitis in humans. In this work, the functional genomics method of signature-tagged mutagenesis (STM) was adapted to E. coli K1 and the infant-rat model to identify non-capsule virulence genes. Validation of the method was demonstrated by the failure to recover a reconstructed acapsular mutant from bacterial pools used to systemically infect 5-day-old rats. Three new genes required for systemic disease were identified from a total of 192 mutants screened by STM (1.56% hit rate). Gut colonization, Southern blot hybridization, mixed-challenge infection, and DNA sequence analyses showed that the attenuating defects in the mutants were associated with transposon insertions in rfaL (O antigen ligase), dsbA (thiol:disulfide oxidoreductase), and a new gene, puvA (previously unidentified virulence gene A), with no known homologues. The results indicate the ability of STM to identify novel systemic virulence factors in E. coli K1.     

Dinuclear copper(II) complexes with valsartan. Synthesis, characterization and cytotoxicity

Two novel dinuclear complexes involving the antihypertensive drug valsartan and copper(II) ion have been prepared in water and DMSO. The complex compositions were determined as: [Cu(vals)(H₂O)₃]₂.6H₂O and [Cu(vals)(H₂O)₂DMSO]₂.2H₂O. They were thoroughly characterized by elemental and thermal analysis, spectrophotometric titrations and UV-visible, diffuse reflectance, FTIR, Raman and EPR spectroscopies. No effect of the ligand on two tested osteoblastic cell lines in culture (one normal MC3T3E1 and one tumoral UMR106) was observed in concentrations up to 100 μM. Higher concentrations of Valsartan are required to induce cytotoxicity in both cell lines. The antiproliferative effect of the tested complex ([Cu(vals)(H₂O)₃]₂.6H₂O) in a dose-response manner, was higher in the UMR106 osteoblastic cell line than that of the MC3T3E1 normal line at concentrations ≥ 100 μM. Morphological alterations are in accordance with proliferative observations.     

综述:中药治疗阿尔茨海默病的作用特点

阿尔茨海默病(AD)是一种多因素相关的复杂性疾病,目前临床治疗效果不佳．仅针对单靶点或单致病途径的药物不易取得好的疗效．另一个重要原因是干预时机太晚,当诊断出痴呆时患者脑内已有大量神经元死亡．因此,应当针对多靶点、多途径治疗,同时将治疗时机提前到痴呆发生前,才有可能在AD的药物干预领域实现新的突破．本文综述了作者近十多年来在中药治疗AD方面的研究工作,包括中药新复方参乌胶囊、中药提取物何首乌二苯乙烯苷、山茱萸环烯醚萜苷、淫羊藿黄酮和淫羊藿苷对多种拟AD动物模型和细胞模型的影响及其作用机制．这些中药的特点是作用在AD复杂发病机制的多靶点和多途径,尤其是具有神经保护和神经营养/再生作用,且对线粒体和突触具有明显的保护作用,可望用于AD的早期干预或轻度认知障碍期(MCI)的治疗,从而阻止或延缓痴呆的发生与进程．     

硝苯地平联合缬沙坦治疗老年原发性高血压疗效分析

目的:探讨硝苯地平缓释片联合缬沙坦治疗老年原发性高血压的临床疗效。方法:将180例患者随机分入对照组与观察组,给予对照组86例患者硝苯地平缓释片口服降压;观察组94例患者接受硝苯地平缓释片联合缬沙坦治疗,比较两组患者治疗8周后血压、心率、脉压、肾功、尿酸、血钾及尿微量白蛋白的变化。结果:治疗后观察组患者收缩压、舒张压、脉压及心率均显著降低,治疗总有效率高于对照组,两组比较差异有统计学意义(P<0.01);观察组尿酸、尿微量白蛋白显著优于对照组(P<0.01),两组肾功、血钾比较差异无统计学意义(P>0.05)。结论:硝苯地平缓释片联合缬沙坦治疗老年原发性高血压,降压平稳,同时可显著降低尿酸及尿微量白蛋白,改善肾功能。     

中药麝香胶囊抑瘤作用的实验研究

目的探讨中药麝香胶囊对小鼠实验性肿瘤的疗效。方法昆明小鼠分别接种艾氏腹水癌、S-180、肝癌细胞株（hepatocellular carcinoma,HCC）三种癌细胞株,接种24h后开始给予中药麝香胶囊,每日1次,共10d。分高、中、低三个剂量给药（4、2、1g／kg以主药麝香药量计）。阳性对照以天仙丸胶囊（1g／kg）一次性灌服。阴性对照组以同体积生理盐水灌服。接种实体瘤动物于第10天处死,称瘤重,计算抑瘤率;接种腹水瘤动物,观察存活时间,计算生命延长率。结果中药麝香胶囊对实体癌有一定的抑瘤作用,但未达到药典规定的抑瘤率30％的要求;对腹水癌也有一定的抑瘤作用,但也未达到药典规定生命延长率50％的要求;统计学分析（P〉0．05）差异没有显著性。结论中药麝香胶囊抑瘤作用不明显,其配方及剂型有待进一步研究与改进。     

眠安胶囊原料药的提取工艺研究

目的:研究眠安胶囊的有效部位及黄芩和琥珀等药材的提取条件.方法:采用正交试验设计,以黄芩苷含量和提取物收率为指标,筛选出了黄芩提取的最佳条件为黄芩粉碎为最粗粉,用10倍水煎煮1.5h后再用8倍量水煎煮0.5h,减压浓缩(60 ℃～70 ℃)煎液至体积为投料量的5倍,于70 ℃加稀盐酸调pH值为1～2,保温30min后静置8h;以药效学为指标,确定了琥珀等药材渗漉提取用乙醇的浓度为70%,同时以药效学和干浸膏得率为指标,通过单因素试验确定了琥珀等药材提取的最优条件为10倍量70%乙醇浸渍24h,调渗漉速度为3 ml·min-1·kg-1进行渗漉提取.结果:眠安胶囊的有效部位为黄芩用水煎煮、琥珀等用乙醇渗漉提取的部位.结论:该工艺稳定,重复性好,适合于眠安胶囊原料药的提取.     

步长稳心颗粒治疗功能性早搏60例疗效分析

目的：观察步长稳心颗粒（简称稳心颗粒）治疗功能性早搏的临床疗效及安全性。方法：选择功能性早搏60例病人,随机分为治疗组及对照组,每组各30例。治疗组给予稳心颗粒一包（9克）,每日三次,温开水冲服;对照组给予倍他乐克25毫克,每日二次口服,一个月为一疗程。结果：四周后治疗组显效11例,有效16例,总有效率90％。对照组显效8例,有效18例,总有效率86．7％,p〉0．05,两组比较无显著性差异。对血压、心率影响方面稳心颗粒明显优于倍他乐克结论：稳心颗粒治疗功能性早搏疗效显著,且效果稳定,安全无明显不良反应,值得临床推广应用。     

黄芪种子萌发特性的研究

运用室内测定方法,对黄芪野生种子和栽培种子的吸不率及其不同处理下的种子发芽率进行了比较试验,结果表明,采用砂磨方法可使黄芪种子的萌发率明显高于其它方法,黄芪各子种皮的机械抵制是导致发芽率低的直接原因;黄芪种子在23℃/15℃变温度条件一的萌发率;不同采收期也会通过影响种子的成熟度而影响发芽率。