稳定分泌重组HBV载体颗粒细胞系的构建

目的 制备一个持续分泌表达杀稻瘟菌素抗性基因(BsdR)的重组乙型肝炎病毒细胞系.方法 删除HBV质粒中各基因的表达,在S基因区插入目的 基因BsdR,以构建载体质粒pCH-BsdR;具有G418抗性的无包装信号的HBV辅助质粒pcDNA3.1-CH3142与载体质粒共转染HepG2细胞,经G418和Bsd共筛选,获得细胞克隆,进行系列检测.结果 挑选36个细胞克隆,经检测,最终筛选出3个细胞株,具有形成松弛环状DNA的能力,细胞培养上清液中病毒定量分别为4.1×106、3.6×106、1.2×106拷贝/ml.观察到有囊膜的重组HBV颗粒的形成.未检测到野生型HBV的产生.结论 该细胞系能够大量制备重组HBV载体颗粒,有助于HBV载体在基因治疗方面的应用和易感细胞系的筛选.     

表没食子儿茶素没食子酸酯联合叶酸杀伤胃癌细胞的实验研究

背景：表没食子儿茶素没食子酸酯（EGCG）具有抗肿瘤作用，对不同胃肠道肿瘤细胞系具有不同程度的、呈剂量依赖的杀伤作用。叶酸是一种水溶性维生素，叶酸缺乏可增加肿瘤的发生率，影响肿瘤细胞凋亡。目的：研究EGCG联合叶酸对胃癌细胞杀伤作用的影响。方法：以甲基噻唑基四唑（MTT）比色法检测EGCG联合叶酸对胃癌细胞系MKN45、SGC7901、MKN28的杀伤作用。流式细胞仪测定两者对MKN45细胞周期的影响。结果：EGCG联合叶酸较EGCG单独作用对MKN45、SGC7901、MKN28细胞的杀伤作用增强，EGCG半数抑制浓度（IC50）分别降低28．4％、51．9％和40．0％。3种浓度的EGCG联合叶酸作用48h后，MKN45细胞的细胞周期分布与对照组和EGCG组相比无明显变化（P〉0．05）。结论：EGCG联合叶酸较EGCG单独作用对胃癌细胞的杀伤作用增强，但对MKN45的细胞周期分布无明显影响。     

Immune responses elicited by a fourth dose of the HPV-16/18 AS04-adjuvanted vaccine in previously vaccinated adult women

Background

Vaccines are now available for the prevention of HPV-16/18-related cervical infections and pre-cancers, primarily targeting adolescent girls. Since the risk of HPV exposure potentially persists throughout a woman's sexual life, vaccine-derived immunity should be long-term. The current study, HPV-024 (NCT00546078, http://clinicaltrials.gov), assessed the immune memory in North American women who received three doses of HPV-16/18 AS04-adjuvanted vaccine 7 years earlier in HPV-001 (NCT00689741).

Methods

Women vaccinated in HPV-001 received a 4th-dose of the HPV-16/18 vaccine (024-4DV group, N = 65). Post 4th-dose immune responses were compared with post 1st-dose immune responses in cross-vaccination controls (024-3DV group, N = 50). Reactogenicity was compared between the 4th-dose and the 1st-dose administration.

Results

Pre 4th-dose, 100% of subjects in the 024-4DV group remained seropositive for anti-HPV-16/18 antibodies (ELISA). Compared to pre 4th-dose, GMTs for anti-HPV-16 and anti-HPV-18 antibodies were respectively 9.3-fold and 8.7-fold higher at day 7, and 22.7-fold and 17.2-fold higher at month 1. Compared to post 1st-dose, GMTs for anti-HPV-16 and anti-HPV-18 were respectively 80.5-fold and 205.4-fold higher at day 7, and 11.8-fold and 20.5-fold higher at month 1. Furthermore, 68.2% and 77.3% of women had HPV-16/18 specific memory B-cells, respectively, pre 4th-dose, rising to 100% one month post 4th-dose vaccination. The 4th-dose was generally well tolerated.

Conclusion

A 4th-dose of HPV-16/18 AS04-adjuvanted vaccine triggered a rapid and strong anamnestic response in previously vaccinated women, demonstrating vaccine-induced immune memory.     

Importance of the pacing mode in the initiation of ventricular tachyarrhythmia in a canine model of chronic myocardial infarction

The use of unipolar anodal or bipolar pacing, as compared with unipolar cathodal pacing, purportedly increases the likelihood of inducing inadvertent ventricular fibrillation in susceptible patients. In this study, the ability to initiate sustained ventricular tachycardia or fibrillation with unipolar cathodal, unipolar anodal and bipolar pacing modes was compared using programmed ventricular stimulation at 82 subendocardial periinfarction sites in 11 dogs with chronic myocardial infarction. The late diastolic excitability threshold was significantly higher and the ventricular refractory period was significantly shorter (p less than 0.001) with anodal pacing (mean 0.62 mA, 156 ms, respectively) than with pacing in either the cathodal (0.12 mA, 174 ms) or the bipolar (0.13 mA, 173 ms) mode. At a current intensity twice that of the excitability threshold, the introduction of one or two extrastimuli induced ventricular tachycardia and ventricular fibrillation comparably among the three pacing modes. However, when three extrastimuli were used, ventricular fibrillation was induced with anodal pacing twice as frequently (50 [61%] of 82 sites) as with either of the other two pacing modes (each 23 [28%] of 82 sites, p less than 0.001), whereas the induction of ventricular tachycardia remained comparable with anodal pacing (15 [18%] of 82 sites) and cathodal and bipolar pacing (each 14 [17%] of 82 sites). Furthermore, a similarly high incidence of inducibility of ventricular fibrillation was observed with both cathodal pacing (56 [68%] of 82 sites) and bipolar pacing (40 [49%] of 82 sites) when an increased current equal to twice the anodal excitability threshold (1.23 mA) was used.(ABSTRACT TRUNCATED AT 250 WORDS)     

Two dimensional echocardiography in mitral, aortic and tricuspid valve prolapse: The clinical problem, cardiac nuclear imaging considerations and a proposed standard for diagnosis

The mitral valve prolapse syndrome may present with a variety of clinical manifestations and has proved to be a common cause of nonspecific cardiac symptoms in clinical practice. Primary and secondary forms must be distinguished. Myxomatous degeneration appears to be the common denominator of the primary form. The diagnostic standard of this form has not previously been defined because the detection of mitral leaflet tissue in the left atrium (prolapse) on physical examination or angiography is nonspecific. M mode echocardiography has greatly enhanced the recognition of this syndrome but has not proved to be the best diagnostic standard because of its limited view of mitral valve motion. The advent of two dimensional echocardiography has provided the potential means for specific identification of the mitral leaflet motion in systole and can be considered the diagnostic standard for this syndrome. Primary myxomatous degeneration with leaflet prolapse is not localized to the mitral valve. Two dimensional echocardiography has detected in preliminary studies tricuspid valve prolapse in up to 50 percent and aortic valve prolapse in about 20 percent of patients with idiopathic mitral valve prolapse.     

黄芩甙对HBsAg和HBeAg的体外抑制作用

目的：观察黄芩甙(Baicalin,Bai)对2．2．15细胞分泌HBsAg和HBeAg的影响，探讨黄芩甙的体外抗HBV作用。方法：通过四甲基偶氮唑盐(MTT)法观察黄芩甙对2．2．15细胞的影响，采用ELlSA法检测分析黄芩甙对2．2．15细胞分泌m6Ag、HBeAg的抑制作用。结果：黄芩甙在2．2．15细胞上半数毒性浓度大于15mg／ml，在该浓度下对HBsAg、HBeAg的抑制率分别达100％、88％以上，在黄芩甙浓度为0．94～15mg／ml时，对2．2．15细胞分泌HBsAg、HBeAg的抑制率高于70％，治疗指数分别为65．22和21．74。结论：黄芩甙有显著的体外抑制HBV作用，属低毒有效药物，具有潜在的抗HBV开发前景。     

刺槐素在SH-SY5Y细胞氧-葡萄糖剥夺和小鼠脑缺血再灌注中的神经保护作用

目的 探讨刺槐素在SH-SY5Y细胞氧-葡萄糖剥夺和小鼠脑缺血再灌注中的神经保护作用.方法 培养神经母细胞瘤细胞SH-SY5Y,分为正常培养组、氧-葡萄糖剥夺(oxygen-glucose deprivation,OGD)组以及刺槐素小剂量组(1μmol/L)、中剂量组(5μmol/L)和大剂量组(10 μmol/L),复氧24 h后应用噻唑蓝染色法测定细胞存活率,乳酸脱氢酶(lactate dehydrogenase,LDH)法测定LDH漏出率.60只C57小鼠随机分为假手术组、脑缺血再灌注组以及小剂量组、中剂量组和大剂量刺槐素组,每组12只.采用线栓法制作大脑中动脉闭塞模型,缺血再灌注时给予刺槐素腹腔注射(小、中、大剂量组分别为6.25、12.5和25 mg/kg).再灌注后24 h时进行神经功能评分,应用2,3,5-氯化三苯基四氮唑染色检测脑梗死体积.结果 体外实验显示,1 μmol/L、5μmol/L和10 μmol/L刺槐素组SH-SY5Y细胞存活率分别为(90.34±6.87)％(P=0.000)、(85.47 ±2.24)％ (P=0.001)和(81.79±1.77)％(P=0.008),均显著高于OGD组的(70.62± 8.89)％.1μmol/L、5μm/L和10 μm/L刺槐素组SH-SY5Y细胞LDH漏出率分别为(159.11 ±13.11)％ (P=0.021)、(155.12±24.72)％(P=0.011)和(160.92 ±7.83)％ (P =0.027),均显著低于OGD组的(180.35±10.60)％.体内实验显示,大剂量刺槐素组神经功能评分显著低于与脑缺血再灌注组[(1.67±0.85)分对(2.50±0.55)分;P=0.018].小剂量、中剂量和大剂量刺槐素组梗死体积分别为(24.14±7.10)mm3、(17.18±3.19)mm3和(12.86±1.88)mm3,均显著小于脑缺血再灌注组的[(48.81±9.48) mm3](P均=0.000).结论 体外和体内实验均显示,刺槐素具有神经保护作用.     

DTI常用扫描序列原理及比较

磁共振弥散张量成像技术是利用水分子的弥散各向异性进行成像,可用于脑白质纤维研究,常用扫描技术包括单次激发平面回波成像(EPI),线阵扫描弥散成像,导航自旋回波弥散加权成像(LSDI),半傅立叶探测单发射快速自旋回波成像等。每种成像技术各有其优缺点,EPI扫描时间短,图像信噪比高,但存在化学位移伪影、磁敏感性伪影、几何变形;LSDI精确度高,几乎无伪影及变形,但扫描时间过长;导航自旋回波弥散加权成像运动伪影少,但扫描时间长;半傅立叶探测单发射快速自旋回波成像扫描时间短,但图像模糊。综合比较,单次激发平面回波成像是用于临床研究较适宜的方法。