球囊拉伤兔髂动脉内膜的组织形态变化的研究

球囊拉伤血管内膜是目前研究血管内膜增厚,管腔狭窄的方便而切实的模型。因此,对其演变过程的形态学研究是必要的。方法：应用ＰＴＣＡ球囊导管拉伤兔髂动脉,用光镜、电镜和扫描电镜观察拉伤后不同时间的动态变化。结果：拉伤后各期变化不同,拉伤后１周内,以血细胞沉积为主,１周后,内膜开始增生,２至４周增生最快。增生活跃的内膜平滑肌细胞来自活化的中膜平滑肌细胞。内皮细胞增生极慢,４周内未见内膜内皮化,呈虫食样改变。结论：球囊拉伤兔髂动脉内膜,可引起血栓形成,炎症反应,平滑肌细胞增生和细胞外基质堆积,导致血管腔狭窄。此研究为今后的工作提供一定的客观依据     

含翻译增强子的表达载体pSC34的构建及初步应用

１９８８年Ｏｌｉｎｓ［１］发现Ｔ７噬菌体基因１０的先导序列（Ｔ７ｇ１０Ｌ）具有明显的促进基因翻译的作用．本文构建了含Ｔ７ｇ１０Ｌ的表达载体ｐＳＣ３４,并尝试表达了几个不同类型的基因．１材料与方法１．１菌株大肠杆菌菌株ＴＡＰ１０６为本室储存．ＴＡＰ１０...     

Sequential unfolding of ankyrin repeats in tumor suppressor p16

The ANK repeat is a ubiquitous 33-residue motif that adopts a beta hairpin helix-loop-helix fold. Multiple tandem repeats stack in a linear manner to produce an elongated structure that is stabilized predominantly by short-range interactions between residues close in sequence. The tumor suppressor p16(INK4) consists of four repeats and represents the minimal ANK folding unit. We found from Phi value analysis that p16 unfolded sequentially. The two N-terminal ANK repeats, which are distorted from the canonical ANK structure in all INK4 proteins and which are important for functional specificity, were mainly unstructured in the rate-limiting transition state for folding/unfolding, while the two C-terminal repeats were fully formed. A sequential unfolding mechanism could have implications for the cellular fate of wild-type and cancer-associated mutant p16 proteins.     

一种新型的重组单链三特异抗体的构建与表达

双特异抗体由于其缺乏共刺激信号 ,激活的T细胞往往会导致凋亡。为了更有效地杀伤肿瘤细胞 ,构建了抗卵巢癌单链×抗CD3单链×抗CD2 8单域重组三特异抗体的表达载体。利用大肠杆菌中的分子伴侣FkpA与三特异抗体共表达 ,提高了三特异抗体的在BL2 1Star菌中的可溶性原核表达。ELISA结果显示 ,可溶性的重组单链三特异抗体 (sTRI)与SK OV 3细胞的膜抗原 ,Jurkat细胞上的CD3分子以及重组CD2 8抗原均有较强的结合活性。桥连试验证明该抗体能同时与SK OV 3细胞和Jurkat细胞结合。体外杀伤试验表明该抗体能激活外周血T细胞来杀伤肿瘤细胞。形态学观察也进一步说明该抗体具有良好的结合活性以及体外杀伤活性。这种新型的重组单链三特异抗体为基于T细胞的癌症免疫治疗建立了一个新的技术平台。     

Microbial transformation of ginsenoside Rb1 by Rhizopus stolonifer and Curvularia lunata

Of 49 microbial strains screened for their capabilities to transform ginsenoside Rb₁, Rhizopus stolonifer and Curvularia lunata produced four key metabolites: 3-O-[-d-glucopyranosyl-(1,2)--d-glucopyranosyl]- 20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ene (1), 3-O-[-d-glucopyranosyl-(1,2)--d- glucopyranosyl]-20-O-[-d-glucopyranosyl]-3,12, 20(S)-trihydroxydammar-24-ol (2), 3-O-[-d-gluco- pyranosyl-(1,2)--d-glucopyranosyl]-3, 12, 20(S)-trihydroxydammar-24-ene (3), and 3-O--d-glucopyranosyl-3, 12, 20(S)-trihydroxydammar-24-ene (4), identified by TOF-MS, ¹H- and ¹³C-NMR spectral data. Metabolites 1, 3 and 4 were from the incubation with R. stolonifer, and 1 and 2 from the incubation with C. lunata. Compound 2 was identified as a new compound.     

脱氢紫堇碱对正常和低氧豚鼠心肌细胞内钙的影响

目的 :探讨脱氢紫堇碱 (dehydeocorydaline,DHC)及维拉帕米 (verapamil,Ver)对豚鼠心肌细胞内游离钙浓度([Ca2 + ] i)变化的影响。方法 :采用离体豚鼠心脏Langendorff法灌注 ,用荧光指示剂方法 (Fure 2 /AM)标记心肌([Ca2 + ] i)变化。观察低氧后心肌 [Ca2 + ] i 的变化。结果 :①正常氧状态心肌 [Ca2 + ] i 均值为 (1 2 0 .5± 8.3)nmol/L(n =2 0 ) ;②正常氧条件下 ,DHC、Ver均使心肌 [Ca2 + ] i 明显下降。 (3)低氧状态下 ,心肌 [Ca2 + ] i 增加与缺氧时间(程度 )直线相关 (r=0 .98)。④DHC对低氧后心肌 [Ca2 + ] i 增加明显减缓。结论 :DHC在正常氧、低氧条件下阻止心肌细胞内钙超载 ,我们认为DHC可能提高心肌细胞的自我保护作用     

大黄素提高HeLa细胞对三氧化二砷促凋亡敏感性的研究

活性氧(reactive oxygen species,ROS)在三氧化二砷(arsenic trioxide,As2O3)诱导肿瘤细胞凋亡中扮演重要角色。本研究用一种天然蒽醌类物质——大黄素(emodin)作为提高HeLa细胞ROS水平的手段,考察其对As2O3促凋亡敏感性的影响,并探究可能涉及的信号传导机制。结果显示大黄素10μmol／L提高ROS并增加了HeLa细胞在As2O32μmol／L作用下的凋亡率,对正常成纤维细胞却无影响。该联合作用可以促进HeLa细胞线粒体跨膜电位降低;抑制转录因子NF-κB激活。本研究提示：大黄素通过提高ROS介导凋亡信号传导的增强和生存信号传导的抑制,增加HeLa细胞对As2O3促凋亡的敏感性。     

Rapid tau aggregation and delayed hippocampal neuronal death induced by persistent thrombin signaling

Tau hyperphosphorylation, leading to self-aggregation, is widely held to underlie the neurofibrillary degeneration found in Alzheimer's disease (AD) and other tauopathies. However, it is unclear exactly what environmental factors may trigger this pathogenetic tau hyperphosphorylation. From several perspectives, the coagulation serine protease, thrombin, has been implicated in AD and activates several different protein kinase pathways but has not previously been shown how it may contribute to AD pathogenesis. Here we report that nanomolar thrombin induced rapid tau hyperphosphorylation and aggregation in murine hippocampal neurons via protease-activated receptors, which was followed by delayed synaptophysin reduction and apoptotic neuronal death. Mechanistic study revealed that a persistent thrombin signaling via protease-activated receptor 4 and prolonged downstream p44/42 mitogenactivated protein kinase activation are at least in part responsible. These results pathogenetically linked thrombin to subpopulations of AD and other tauopathies associated with cerebrovascular damage. Such knowledge may be instrumental in transforming therapeutic paradigms.     

Simulating structural and thermodynamic properties of carcinogen-damaged DNA

A pair of stereoisomeric covalent adducts to guanine in double-stranded DNA, derived from the reaction of mutagenic and tumorigenic metabolites of benzo[a]pyrene, have been well characterized structurally and thermodynamically. Both high-resolution NMR solution structures and an array of thermodynamic data are available for these 10S (+)- and 10R (-)-trans-anti -[BP]-N(2)-dG adducts in double-stranded deoxyoligonucleotides. The availability of experimentally well-characterized duplexes containing these two stereoisomeric guanine adducts provides an opportunity for evaluating the molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) method for computing thermodynamic properties from molecular dynamics ensembles. We have carried out 3-ns molecular dynamics simulations, using NMR solution structures as the starting models for the 10S (+)- and 10R (-)-trans-anti-dG adducts in a DNA duplex 11-mer using AMBER 6.0. We employed the MM-PBSA method to compute the free energies, enthalpies, and entropies of the two adducts. Our complete thermodynamic analysis agrees quite well with the full experimental thermodynamic characterization of these adducts, showing essentially equal stabilities of the two adducts. We also calculated the nuclear Overhauser effect (NOE) distances from the molecular dynamics trajectories, and compared them against the experimental NMR-derived NOE distances. Our results showed that the simulated structures are in good agreement with the NMR experimental NOE data. Furthermore, the molecular dynamics simulations provided new structural and biological insights. Specifically, the puzzling observation that the BP aromatic ring system in the 10S (+)-trans-anti-dG adduct is more exposed to the aqueous solvent than the 10R (-)-trans-anti-dG adduct, is rationalized in terms of the adduct structures. The structural and thermodynamic features of these stereoisomeric adducts are also discussed in relation to their reported low susceptibilities to nucleotide excision repair.