神经导航中脑组织变形补偿的点云处理

有限元方法是解决神经导航中脑组织变形的重要方法,需要手术过程中的脑皮层信息作为其边界条件.本文通过非结构点云进行了脑皮层信息的表示,并通过对其进行处理来获取有限元方法的边界条件.点云处理包括纹理映射、分割、简化和去噪,其中非结构点云的简化与去噪采用了改进的基于表面特性k邻域的聚类方法.实验结果证明所采用的点云处理方法是可靠的.     

db-cAMP对转化细胞增殖抑制及其对CaM水平和PKⅡ活性的影响

目的　探讨双丁酰 环核苷酸 (db cAMP)对转化细胞增殖及细胞表型作用的机理。　方法　以流式细胞光度术 (flowcytometry ,FCM)、软琼脂集落形成、放射免疫、Northern印迹和激酶活性分析等方法观察db cAMP对转化的C3H1 0 T1 2 小鼠成纤维细胞增殖、细胞表型、钙调素 (calmodulin ,CaM)表达及蛋白激酶Ⅱ (proteinkinaseⅡ ,PKⅡ )活性的影响。　结果　db cAMP(1mmol L)使C3H1 0 T1 2 转化细胞增殖及软琼脂集落形成能力受到显著抑制 ,转化细胞中CaM的表达及PKⅡ活性明显高于正常细胞 ,经db cAMP处理后也受到明显抑制。　结论　细胞转化及cAMP的诱导分化作用与PKⅡ活性的改变有密切相关性     

吗氯贝胺与米帕明治疗抑郁症多中心双盲对照试验

目的 :以经典抗抑郁药物米帕明为阳性对照药采用随机双盲双模拟方法对吗氯贝胺和米帕明治疗抑郁症的疗效和安全性进行研究。方法 :共纳入病人 2 0 0例 ,分别口服吗氯贝胺 3 0 0 -60 0mg d或米帕明75 -2 5 0mg d。结果 :两组病人Hamilton抑郁量表 (HAMD)以及Hamilton焦虑量表 (HAMA)总分在治疗结束时均显著下降 (P <0 0 0 1)。两组之间疗效无显著差异 (p >0 0 5 )。治疗结束时HAMD减分率分别为吗氯贝胺组 0 74± 0 2 4,米帕明组 0 74± 0 2 4(P >0 0 5 ) ;有效率吗氯贝胺组 79 4% ,米帕明组 85 4% (P >0 0 5 )。吗氯贝胺组有 10种不良反应发生频率显著低于米帕明组 ,主要是抗胆碱能、中枢神经系统及心血管系统不良反应。吗氯贝胺的疗效指数也显著高于米帕明组。结论 :吗氯贝胺是一种安全有效的抗抑郁药物     

Interleukin-18 expression induced by Epstein-Barr virus-infected cells

Human Epstein-Barr virus (EBV)-negative Burkitt lymphomas cells usually grow as malignant subcutaneous tumors in athymic mice, but these tumors regress when the Burkitt cells are injected in conjunction with EBV-positive lymphoblastoid cells or when the Burkitt cells are transfected with the EBV latent membrane protein-1 (LMP-1) gene. Tumor regression is mediated, in part, by murine interferon gamma (IFN-gamma) and the IFN-gamma-induced murine chemokine IFN-gamma-inducible protein-10 (IP-10). The mechanisms by which EBV-LMP-1 promotes the expression of IFN-gamma has remained unclear. Here we show that murine interleukin (IL)-18 was consistently expressed in regressing Burkitt tumors but was either expressed at low levels or absent from progressively growing Burkitt tumors. By immunohistochemical methods, IL-18 protein was visualized in regressing but not in progressively growing Burkitt tumors. In contrast, IL-12 p35 and IL-12 p40 were only rarely expressed in regressing Burkitt tumors. In splenocyte cultures, EBV-infected lymphoblastoid cells and LMP-1-transfected Burkitt cells promoted the expression of IL-18 but not the expression of IL-12 p35 and IL-12 p40. A neutralizing antibody directed at murine IL-18 reduced murine IP-10 expression induced by EBV-immortalized cells in splenocyte cultures. These results provide evidence for IL-18 expression in response to a viral latency protein and suggest that IL-18 may play an important role as an endogenous inducer of IFN-gamma expression, thereby contributing to tumor regression.     

Mechanism of inhibition of HIV-1 infection in vitro by purified extract of Prunella vulgaris.

Crude extracts of four Chinese herbs, Arctium lappa, Astragalus membranaceus, Andrographis paniculata, and Prunella vulgaris, were assessed in several tissue culture lines for anti-HIV activity and for cytotoxicity. One extract, obtained from P. vulgaris, was able to significantly inhibit HIV-1 replication with relatively low cytotoxicity. The active factor was purified using sequential precipitations with ethanol and n-butanol, followed by reverse-phase and gel permeation high-performance liquid chromatographic separations. The active component was anionic with a molecular weight of approximately 10 kDa. The purified extract inhibited HIV-1 replication in the lymphoid cell line MT-4, in the monocytoid cell line U937, and in peripheral blood mononuclear cells at effective concentrations of 6, 30, and 12.5 micrograms/ml, respectively. Pretreatment of uninfected cells with the extract prior to viral exposure did not prevent HIV-1 infection. By contrast, preincubation of HIV-1 with the purified extract dramatically decreased infectiousness. The purified extract was also able to block cell-to-cell transmission of HIV-1, prevented syncytium formation, and interfered with the ability of both HIV-1 and purified gp120 to bind to CD4. PCR analysis confirmed the absence of HIV-1 proviral DNA in cells exposed to virus in the presence of the extract. These results suggest that the purified extract antagonizes HIV-1 infection of susceptible cells by preventing viral attachment to the CD4 receptor.     

Clamp loading,unloading and intrinsic stability of the PCNA, β and gp45 sliding clamps of human,E. coli and T4 replicases

Background: The high speed and processivity of replicative DNA polymerases reside in a processivity factor which has been shown to be a ring-shaped protein. This protein (‘sliding clamp’) encircles DNA and tethers the catalytic unit to the template. Although in eukaryotic, prokaryotic and bacteriophage-T4 systems, the processivity factors are ring-shaped, they assume different oligomeric states. The Escherichia coli clamp (the β subunit) is active as a dimer while the eukaryotic and T4 phage clamps (PCNA and gp45, respectively) are active as trimers. The clamp can not assemble itself on DNA. Instead, a protein complex known as a clamp loader utilizes ATP to assemble the ring around the primer-template. This study compares properties of the human PCNA clamp with those of E. coli and T4 phage. Results: The PCNA ring is a stable trimer down to a concentration below 100 nm (K_d ≈ 21 nm ). On DNA, the PCNA clamp slides freely and dissociates from DNA slowly (t_1/2 ≈ 24 min). β is more stable in solution (K_d < 60 pm ) and on DNA (t_1/2 ≈ 1 h) than PCNA which may be explained by its simpler oligomeric state. The T4 gp45 clamp is a much less stable trimer than PCNA (K_d ≈ 250 nm ) and requires association with the polymerase to stabilize it on DNA as observed previously. The consequence of this cooperation between clamp and polymerase is that upon finishing a template and dissociation of the polymerase from DNA, the gp45 clamp spontaneously dissociates from DNA without assistance. However, the greater stability of the PCNA and β clamps on DNA necessitates an active process for their removal. The clamp loaders (RF-C and γ complex) were also capable of unloading their respective clamps from DNA in the presence of ATP. Conclusions: The stability of the different clamps in solution correlates with their stability on DNA. Thus, the low stability of the T4 clamp explains the inability to isolate gp45 on DNA. The stability of the PCNA and β clamps predicts they will require an unloading factor to recycle them on and off DNA during replication. The clamp loaders of PCNA and β double as clamp unloaders presumably for the purpose of clamp recycling.     

PCOS患者AMH水平与性激素及胰岛素抵抗的相关性研究

目的 探讨多囊卵巢综合征(PCOS)患者血清抗苗勒管激素(AMH)水平与性激素及胰岛素抵抗(IR)的相关性.方法 选取2019年1月至12月在西安交通大学第一附属医院妇科内分泌门诊及西北工业大学医院妇科确诊的PCOS患者109例,测定患者血清AM H、性激素水平,应用稳态模型评估胰岛素抵抗指数(HOMA-IR),分析PCOS患者不同AM H水平的性激素及IR值的差异,以及性激素、IR对AM H的影响.结果 对PCOS患者,根据血清AM H检测值按百分位(<25％,25％ ～75％,>75％)进行分层,随着AMH百分位逐渐升高,体质量指数(BMI)、HOMA-IR值均降低(F值分别为3.354、3.712,P<0.05),同时黄体生成素(LH)、睾酮(T)值均升高(F值分别为3.355、3.317,P<0.05).相关性分析显示,血清AMH水平与BMI、HOMA-IR均呈显著负相关(r分别为-0.228、-0.214,P<0.05),与L H、T均呈显著正相关(r分别为0.344、0.327,P<0.01).进一步多元回归分析显示,在控制BMI后,LH及T对AMH存在显著正向影响(β=0.258,P<0.05;β=0.291,P<0.01).结论 PCOS患者血清AMH水平与LH、T均呈正相关,其与HOMA-IR的负相关关系可以由BMI解释.     

重点高中生的心理状态与高考成绩的相关性研究

目的;了解重点高中学生的心理状态与高考成绩之间的关系。方法：以398例应届生为对象,应用16PF人格测验,气质测量工具（STI,TTI）及焦虑自评量表（SAS）,对考生进行测试分析,结果：文理科学生的16PF的人格特质有明显的差别,判别分析和多因素回归分析显示16PF人格特质中的Q1因素（实验性F＝8．76,P＜0．01）,Q2因素（独立性F＝8．23,P＜0．01）,与高考成绩呈正相关,与M因素（幻想性F＝4．88,P＜0．01）,呈负相关;气质中的神经过程灵活性（F＝8．15,P＜0．01）和时间特质中的灵活性（F＝12．36,P＜0．01）与高才成绩呈正相关。结论：高考生的实验性,独立性高分及幻想性低分的个性特质和气质上的灵活性有助于高考成绩的发挥,学生文理科分班宜参考学生人格特质这一特点,。