椎间盘部分切除对腰椎应力分布影响的有限元分析

腰椎间盘突出症是骨科常见病之一。椎间盘切除术被广泛应用于本症的治疗。本文采用有限元素分析法观察了椎间盘部分切除前后腰椎应力分布的改变。本研究观察到,在正常情况下,椎体上下缘的中央部位承受较大的应力;椎间盘部分切除术后,椎体上下缘的侧方承采应力大于中央部分。这些结果表明,椎间盘部分切除术后可引起腰椎应力分布紊乱,出现应力集中,引起骨质增生,从而影响手术的远期疗效。     

110例癫痫患者24hAEEG临床应用报告

目的对１１０例癫痫患者的２４ｈ动态脑电图（ＡＥＥＧ）的应用价值进行了初步探讨。方法使用英国的ＯｘｆｏｒｄＭｅｄｉｌｏｇ９２００型８导磁带记录仪进行２４ｈ描记后作离线回放分析，并与普通ＥＥＧ相比较。结果１１０例中ＡＥＥＧ异常６２例（５６．４％），９８例中ＥＥＧ发现异常３２例（３２．７％）。ＥＥＧ正常而ＡＥＥＧ异常３０例，ＥＥＧ异常而ＡＥＥＧ正常９例。结论ＡＥＥＧ明显优于ＥＥＧ，但有时ＡＥＥＧ也不能捕获到间歇期的发作波。分析ＡＥＥＧ记录必需注意将睡眠Ⅰ、Ⅱ期出现的高幅顶尖波、纺锤波与痫样波区分开来，以免导致错误诊断。ＡＥＥＧ对颞叶和额叶底面的致痫灶反应较差，需补做特殊电极的ＥＥＧ，如蝶骨电极。     

Inactivation of Exonuclease 1 in mice results in DNA mismatch repair defects,increased cancer susceptibility,and male and female sterility

Exonuclease 1 (Exo1) is a 5'-3' exonuclease that interacts with MutS and MutL homologs and has been implicated in the excision step of DNA mismatch repair. To investigate the role of Exo1 in mammalian mismatch repair and assess its importance for tumorigenesis and meiosis, we generated an Exo1 mutant mouse line. Analysis of Exo1(-/-) cells for mismatch repair activity in vitro showed that Exo1 is required for the repair of base:base and single-base insertion/deletion mismatches in both 5' and 3' nick-directed repair. The repair defect in Exo1(-/-) cells also caused elevated microsatellite instability at a mononucleotide repeat marker and a significant increase in mutation rate at the Hprt locus. Exo1(-/-) animals displayed reduced survival and increased susceptibility to the development of lymphomas. In addition, Exo1(-/-) male and female mice were sterile because of a meiotic defect. Meiosis in Exo1(-/-) animals proceeded through prophase I; however, the chromosomes exhibited dynamic loss of chiasmata during metaphase I, resulting in meiotic failure and apoptosis. Our results show that mammalian Exo1 functions in mutation avoidance and is essential for male and female meiosis.     

<Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> Ats1p interacts with Nap1p,a cytoplasmic protein that controls bud morphogenesis

Saccharomyces cerevisiae ATS1 (-tubulin suppressor 1) was originally identified as a high-copy suppressor of class two -tubulin mutations and was proposed to have a regulatory role in coordinating the microtubule state with the cell cycle. Here, we show that Ats1p interacts with Nap1p, a cytoplasmic protein that regulates the activity of the Cdc28p/Clb2p complex. Loss of Nap1p results in a delayed switch from polar to isotropic bud growth. The delayed switch results in elongated buds. Nap1p and Ats1p interact in two-hybrid and co-immunoprecipitation assays. Both nap1 and ats1 cells have a Clb2p-dependent elongated bud morphology. Deletion of ATS1 partially suppresses the elongated bud morphology and benomyl resistance of nap1 mutants. Our results suggest Ats1p might regulate coordination of the microtubule state with the cell cycle through an interaction with Nap1p.Communicated by S. Hohmann     

乙/丙型肝炎病毒双重感染患者前C区终止变异低频率

目的了解乙型肝炎病毒（ＨＢＶ）与丙型肝炎病毒（ＨＣＶ）双重感染患者前Ｃ区基因变异，及其可能的临床意义。方法用聚合酶链反应（ＰＣＲ）与限制片段长度多态性（ＲＦＬＰ）来分析２５例ＨＢＶＤＮＡ和ＨＣＶＲＮＡ均阳性（Ａ组）和３１例ＨＢｓＡｇ和ＨＢＶＤＮＡ阳性但抗－ＨＣＶ和ＨＣＶＲＮＡ均阴性（Ｂ组）的慢性肝病患者前Ｃ区密码２８终止变异（终２８）。结果ＨＢＶ和ＨＣＶ双重感染患者（Ａ组）血清ＨＢＶＤＮＡ第１次ＰＣＲ阳性率（１６％）明显低于单独ＨＢＶ感染组（６５％）（Ｐ＜０．００１）；前Ｃ终２８检出率（２８％）亦明显低于单独ＨＢＶ感染（６８％）（Ｐ＜０．００１）。结论提示双重感染患者ＨＢＶ前Ｃ终止变异低频率可能与ＨＢＶ低水平复制有关     

Integrated medical informatics with small group teaching in medical education

National Taiwan University College of Medicine (NTUCM) introduced small groups of teaching and basic-clinical integrated courses for medical students in 1992. By using computer network and multimedia techniques, this study tried to overcome barriers to learning in small group teaching. The Department of Medical Informatics of NTUCM established campus networking and computer classrooms and provided Internet and intranet network services including mail, netnews, bulletin board systems (BBS), world wide web (WWW), gopher, ftp and local file servers. To implement an interactive learning environment, the authors first tried mail lists, newsgroups and BBS. Next an integrated learning system prototype on the WWW was developed to provide functions including online syllabus, discussion boards simulated to BBS, online talk, interactive case studies, virtual classroom with video on demand (VOD) and Internet medical resources. The results showed that after the medical students completed the required course of medical informatics and had good network access using a network to communicate with each other became a daily practice. In the future, the system will extend to the tutoring of clinical practice and continuing medical education. The authors expect a national medical education network and more international cooperation and exchange.     

CD1d-restricted natural killer T cells are potent targets for human immunodeficiency virus infection

Invariant human natural killer T cells (NKT) express a restricted T-cell receptor (TCR) Valpha24Vbeta11 repertoire. These cells share both phenotypic and functional similarities between NK and T cells. Given the emerging role of NKT cells as critical cells in bridging the gap between innate and adaptive immunity, we examined their susceptibility to productive human immunodeficiency virus (HIV) infection by T-tropic, M-tropic, and primary isolates of HIV. We generated three human NKT cell clones (CA5, CA29, and CA31). Phenotypic characterization of these Valpha24+ Vbeta11+ clones indicated that they were predominately positive for CD4, CD161, HLA-DR, CD38, CD45RO, and CD95 expression. The NKT cell clones expressed significantly more surface CCR5 molecules/cell and lower CXCR4 molecules/cell than phytohaemagglutinin-stimulated peripheral blood mononuclear cells (PBMC). Consistent with the surface expression of CCR5 and CXCR4, the NKT clones were also selectively susceptible to HIV M-tropic, T-tropic, and primary isolate infection, as evaluated by both HIV p24 enzyme-linked immunosorbent assay and intracellular staining of HIV proteins. The amount of p24 production was dependent on the NKT clone studied and the HIV strain used. Clones CA29 and CA31 were also susceptible to HIV IIIB infection. The virions produced by these clones were able to productively infect PHA-stimulated PBMCs with the same kinetics as for primary infection of CD4+ blast. Collectively, this data demonstrates that NKT cells can be a target for productive HIV infection but with a lag in the time to peak p24 production.     

hTRT催化功能区基因克隆及其在肿瘤中的表达

目的 研究端粒酶蛋白ｈＴＲＴ基因在肿瘤中的表达及其意义。方法 用ＲＴ－ＰＣＲ法检查Ｈｅｌａ细胞与ＰＧ细胞的ｈＴＲＴ表达水平,将Ｈｅｌａ细胞的ｈＴＲＴ催化功能克隆,并进行测序比较,应用原位杂交技术对肿瘤组织中的ｈＴＲＴ和ｈＴＲ（端粒酶ＲＮＡ组分）基因进行检测。结果 Ｈｅｌａ细胞与ＰＧ细胞均有ｈＴＲＴ表达,Ｈｅｌａ细胞ｈＴＲＴ催化功能区ｃＤＮＡ序列与文献报道一致,原位杂交结果显示ｈＴＲＴ与ｈＴＲ的协同     

痘苗病毒VGF细胞膜外结构域在真核及原核细胞中的表达

目的为了进一步探索ＶＧＦ的生物学功能方法分别构建了痘苗病毒天坛株生长因子（Ｖａｃｃｉｎｉａｇｒｏｗｔｈｆａｃｔｏｒ，ＶＧＦ）基因细胞膜外结构域（ＶＧＦｓｌ）的真核及原核表达系统，在相应的细胞中获得了单独表达（真核）和融合表达（原核）。结果初步纯化的ＶＧＦｓｌ表达产物能够与上皮生长因子（ＥＧＦ）的受体结合，并刺激受体中酪氨酸残基发生磷酸化反应。与ＥＧＦ相比，ＶＧＦｓｌ表达产物刺激ＥＧＦ受体自身磷酸化的能力更强。结论上述结果为ＶＧＦ在病毒感染过程中的作用以及ＶＧＦ作为新型多肽类药物的研究提供了有价值的线索。