重组合异种骨修复良性骨肿瘤术后骨缺损的疗效观察

目的：观察一种复合异种骨修复良性骨肿瘤手术切除后骨缺损的临床疗效。方法：重组合异种骨（RBX）治疗36例良性骨肿瘤手术后的骨缺损，其中男20例，女16例；年龄8～62岁，平均31岁。观察手术后的并发症及骨愈合情况。结果：获得随访32例，平均随访时间12个月，最短10个月，最长24个月。有一例并发术后感染，26例在第9个月经x线片和CT证实获得骨性愈合，在随访期内未发生肿瘤复发。结论：RBX是一种较为理想的骨缺损修复材料，对良性骨肿瘤术后骨缺损的修复具有较为可靠的疗效。     

辐射处理后猪软骨异种移植的实验研究

目的：为观察经辐射处理的猪软骨异种移植后的改变，采用辐射处理后的猪软骨分期移植到大白兔皮下，分期观察移植后的变化，并用新鲜猪软骨作为对照。方法：实验分三组，经γ-射线处理后4℃保存三个月的猪软骨为A组；保存一个月的为B组；新鲜猪软骨为C组。结果：γ-射线辐射处理可降低猪软骨的抗原性，以4℃保存一个月为最佳保存时间。结论：猪软骨经辐射处理后可作为异种移植代用材料的最佳来源。     

转人α1,2岩藻糖苷转移酶基因猪动脉内皮细胞抗人血清溶破实验

目的研究转入α1,2岩藻糖苷转移酶(HT)基因克服异种移植超急排斥反应(HAR)的作用。方法构建pcDNA3-HTcDNA重组质粒,体外培养猪动脉内皮细胞(PAEC),脂质体转染法将pcDNA3-HTcDNA转染PAEC,新霉素(G418)筛选具有抗性的细胞克隆,PCR检测重组基因的整合,流式细胞术(FCM)检测转染细胞H抗原和异种抗原α—Gal表达。分别以未转染的PAEC和人脐静脉内皮细胞(HUVEC)作对照。将转染细胞和正常细胞分别以20％、40％和60％人血清孵育2 h,比较溶破细胞百分数。结果重组质粒转染PAEC经筛选得到抗性细胞克隆,PCR扩增出人HT基因片段,FCM检测正常PAEC与转染PAEC,α-Gal平均荧光强度由1346．81降至194．44,H抗原平均荧光强度由9．10增至215．93;α—Gal M2区由99．98％降至37．180A,H抗原M2区由13．80％升至78．54％。转染细胞以人血清孵育后溶破细胞百分数较正常细胞降低,分别由(32．32±2．37)％、(59．54±4．56)％和(71．46±5．94)％降至(15．78±2．69)％、(30．16±1．46)％和(40．48±3．77)％,差异均有统计学意义(P值均<0．05)。结论转人HT基因PAECα—Gal表达明显降低,H抗原表达升高,对人血清溶破的耐受性增强。转人HT基因可以一定程度抑制HAR。     

Studies on the effects of heterologous antisera against subcellular thymocyte fraction

Subcellular fractions of mice thymocytes were used for sensitization of rabbits. The antisera were examined for their immunosuppressive potency in vivo by allogeneic murine tumor metastases system and on skingraft survival and in vitro by leukocyte agglutination tests. The results indicated that the most potent immunosuppressive antisera was that against the second fraction (Fr. 2) of the detergent soluble endoplasmic reticulum fraction from thymocytes.     

Plant as Bioreactor for Producing Heterologous Proteins

Using plants to produce heterologous proteins makes it very attractive due to the potentially low costs. Using this procedure it is possible to produce medicinal protein for clinical applications with the plants bioreactors increasing gradually. The paper proposes the five major systems of the plant bioreactor as well as their advantage and disadvantage and the development of each system. Focuses on the five major systems of the plant bioreactor to produce vaccines, antibodies and medical protein and the research achievement at the present stage and the research on my laboratory. The key technology research of plant bioreactor such as new genes, new biological components,new technologies and new research methods related with plant bioreactor offer a work foundation for a long-term development in future.     

Concurrent detection of human herpesvirus type 6 and measles-specific IgMs during acute exanthematic human parvovirus B19 infection

A familial outbreak of human parvovirus B19 infection is described in which serological tests carried out routinely for determining the causal agent of febrile rashes of viral etiology failed to yield a definitive diagnosis. Concurrent detection of serum IgMs to parvovirus B19 and to heterologous viruses such as human herpesvirus type 6 (HHV-6) and measles virus complicated interpretation of the data. IgG avidity tests and investigation and testing for the presence of viral DNA in sera by PCR were required to confirm parvovirus B19. The study stresses the importance of avidity and PCR tests to obtain a firm diagnosis of febrile exanthematic viral diseases.     

Membrane integration of recombinant human P450 forms

1. Amino terminal sequence modification of cytochrome P450 enzymes is often necessary to achieve expression in bacteria. The aim of this study was to examine the effect of such modifications on membrane integration and P450 activity.

2. Forms that retained substantial N-terminal hydrophobic sequences remained unaffected by treatments to remove peripheral membrane proteins and were released only by detergent. Truncated P450s 2A13, 2C9 (δ3–20), 2C19 (δ3–20), 2D6 (DB11) and 2E1 remained principally membrane-bound, but some P450 was found in the soluble fraction and could be partially extracted by alkaline and high salt treatments.

3. The subcellular localization of P450s 2C9 and 2C19 assessed by fluorescence microscopy mirrored the distribution between subcellular fractions. The MALLLAVFL modified forms of P450 2C9 YFP, P450 2C18 YFP and P450 2C19 YFP were found primarily at the periphery of the cells, whereas the truncated forms of P450 2C9 (δ3–20) YFP and 2C19 (δ3–20) YFP were observed at the periphery as well as inside the cells.

4. N-terminal variants of P450s 2C9 and 2C19 showed altered kinetics towards form-selective substrates. Rates of diclofenac 4´-hydroxylation by P450 2C9 and luciferin H-EGE metabolism by P450 2C19 were higher for the MALLLAVFL-modified forms compared with the (δ3–20) truncated forms despite supplementation of truncated form incubations with additional reductase.

5. Thus, N-terminal sequence modifications changed the degree of membrane integration, potentially affecting subcellular localization, interactions with redox partners, and hence enzymatic activity.

     

Expression of biosynthetic gene clusters in heterologous hosts for natural product production and combinatorial biosynthesis

Expression of biosynthetic gene clusters in heterologous hosts for natural product production and combinatorial biosynthesis is playing an increasingly important role in natural product-based drug discovery and development programmes. This review highlights the requirements and challenges associated with this conceptually simple strategy of using surrogate hosts for the production of natural products in good yields and for the generation of novel analogues by combinatorial biosynthesis methods, taking advantage of the recombinant DNA technologies and tools available in the model hosts. Specific topics addressed include: i) the mobilisation of biosynthetic gene clusters using different vector systems; ii) the selection of suitable model heterologous hosts; iii) the requirement of post-translational protein modifications and precursor supply within the model hosts; iv) the influence of promoters and pathway regulators; and v) the choice of suitable fermentation conditions. Lastly, the use of heterologous expression in combinatorial biosynthesis is addressed. Future directions for model heterologous host engineering and the optimisation of natural product biosynthetic gene cluster expression in heterologous hosts are also discussed.     

Heterologous expression of the invertebrate FMRFamide-gated sodium channel as a mechanism to selectively activate mammalian neurons

Considerable effort has been directed toward the development of methods to selectively activate specific subtypes of neurons. Focus has been placed on the heterologous expression of proteins that are capable of exciting neurons in which they are expressed. Here we describe the heterologous expression of the invertebrate FMRFamide (H-phenylalanine-methionine-arginine-phenylalanine-NH(2)) -gated sodium channel from Helix aspersa (HaFaNaC) in hippocampal slice cultures. HaFaNaC was co-expressed with a fluorescent protein (green fluorescent protein (GFP), red fluorescent protein from Discosoma sp (dsRed) or mutated form of red fluorescent protein from Discosoma sp (tdTomato)) in CA3 pyramidal neurons of rat hippocampal slice cultures using single cell electroporation. Pressure application of the agonist FMRFamide to HaFaNaC-expressing neuronal somata produced large prolonged depolarizations and bursts of action potentials (APs). FMRFamide responses were inhibited by amiloride (100 muM). In contrast, pressure application of FMRFamide to the axons of neurons expressing HaFaNaC produced no response. Fusion of GFP to the N-terminus of HaFaNaC showed that GFP-HaFaNaC was absent from axons. Bath application of FMRFamide produced persistent AP firing in HaFaNaC-expressing neurons. This FMRFamide-induced increase in the frequency of APs was dose-dependent. The concentrations of FMRFamide required to activate HaFaNaC-expressing neurons were below that required to activate the homologous acid sensing ion channel normally found in mammalian neurons. Furthermore, the mammalian neuropeptides neuropeptide FF and RFamide-related peptide-1, which have amidated RF C-termini, did not affect HaFaNaC-expressing neurons. Antagonists of NPFF receptors (BIBP3226) also had no effect on HaFaNaC. Therefore, we suggest that heterologous-expression of HaFaNaC in mammalian neurons could be a useful method to selectively and persistently excite specific subtypes of neurons in intact nervous tissue.     

人脐血源性内皮祖细胞血管发生活性及其参与人恶性胶质瘤细胞异种移植瘤血管新生的作用

目的 观察人脐血源性内皮祖细胞(EPC)血管发生能力和在恶性胶质瘤血管新生过程中的作用.方法 应用密度梯度离心法分离新鲜人脐血的单个核细胞,接种于EGM-2培养液中培养获得EPC.取生长到第7～10天的细胞进行CD34和VEGFR-2免疫荧光双标染色.检测血管内皮生长因子(VEGF)刺激下EPC增殖活性、迁移能力和体外形成小管样结构的能力.采用人恶性胶质瘤细胞系U87在免疫缺陷小鼠进行皮下移植,于接种肿瘤后第7天经尾静脉注射EPC(每只5×103),并于接种肿瘤后第28天取材检测肿瘤微血管和EPC组织分布及定位,采用抗人CD31和抗鼠CD31免疫荧光双标记肿瘤微血管,计算人源性EPC来源的血管占肿瘤血管网的比例.结果 培养的细胞在第7～10天时可见条索样结构,生长并逐渐融合形成铺路石样排列的单层细胞,表达内皮细胞标记物CD34和VEGFR-2.在VEGF刺激下EPC具有较强的增殖活性、迁移能力和体外形成小管样结构的能力.外源性EPC能特异性归巢到异种移植瘤组织并形成新生血管,占肿瘤血管网的(18.68±1.32)%.结论 EPC在体内外具有形成血管能力,并参与异种移植瘤血管新生,提示其在恶性肿瘤血管新生过程中具有重要作用,并可能参与肿瘤微血管构筑表型异质性.