神经调节因子及其信号转导机制

神经调节因子(NRG)是一个由4种基因编码的多肽家族,包含4种同源异构体NRG-1,2,3和4,其功能性受体是由ErbB酪氨酸激酶受体组成,属于跨膜酪氨酸激酶的表皮生长因子受体家族成员,包括ErbB2/HER2/neu,ErbB3/HERS和ErbB4/HER4.NRG通过诱导ErbB受体构象变化,使ErbB蛋白形成二聚体,继而激活酪氨酸激酶,引起C-末端的自身酪氨酸磷酸化和反式酪氨酸磷酸化,而发挥其生物学作用.     

Preparation and characterization of porous beta-tricalcium phosphate/collagen composites with an integrated structure

Porous beta-tricalcium phosphate (TCP)/collagen composites with different beta-TCP/collagen weight ratio were prepared. The influences of the preparation conditions on the microstructure of porous composite and the joint status of beta-TCP particles with collagen fibrils were characterized by X-ray diffractometer, scanning electron microscopy and transmission electron microscopy. The results showed: (1) an acid treatment could effectively disassemble collagen fibrils; (2) in the resulting porous composites, beta-TCP particles homogenously existed on the skeleton of the collagen fibril network and bonded tightly to both the fibrils and themselves. The tight bonding formation could be due to the reaction between Ca ions in the particles and carboxyl groups in collagen polypeptide chains and due to the reprecipitation of partially dissolved beta-TCP during synthesis. The tight bonding between beta-TCP particles and collagen fibrils in the composites demonstrated an integrated structure, which was reproducible when beta-TCP/collagen ratio ranged from 2 to 4. Such integrated structure would make significant contributions in reliably tailoring properties of the porous composites by varying beta-TCP content. In addition, the porous composites had large porosity (approximately 95%) and appropriate pore size (approximately 100 microm), showed no negative impact in cytotoxicity assay and complete bone tissue regeneration after 12 weeks in animal test.     

Survey of the Distribution of a Newly Characterized Receptor for Advanced Glycation End Products in Tissues

Advanced glycation end products (AGEs), the final products of nonenzymatic glycation and oxidation of proteins, are found in the plasma and accumulate in the tissues during aging and at an accelerated rate in diabetes. A novel integral membrane protein, termed receptor for AGE (RAGE), forms a central part of the cell surface binding site for AGEs. Using monospecific, polyclonal antibody raised to human recombinant and bovine RAGE, immunostaining of bovine tissues showed RAGE in the vasculature, endothelium, and smooth muscle cells and in mononuclear cells in the tissues. Consistent with these data, RAGE antigen and mRNA were identified in cultured bovine endothelium, vascular smooth muscle, and monocyte-derived macrophages. RAGE antigen was also visualized in bovine cardiac myocytes as well as in cultures of neonatal rat cardiac myocytes and in neural tissue where motor neurons, peripheral nerves, and a population of cortical neurons were positive. In situ hybridization confirmed the presence of RAGE mRNA in the tissues, and studies with rat PC12 pheochromocytes indicated that they provide a neuronal-related cell culture model for examining RAGE expression. Pathological studies of human atherosclerotic plaques showed infiltration of RAGE-expressing cells in the expanded intima. These results indicate that RAGE is present in multiple tissues and suggest the potential relevance of AGE-RAGE interactions for modulating properties of the vasculature as well as neural and cardiac function, prominent areas of involvement in diabetes and in the normal aging process.     

Early embryonic expression patterns of the mouse Flamingo and Prickle orthologues.

The Drosophila melanogaster proteins Flamingo and Prickle act in the planar cell polarity (PCP) pathway, which is required for acquisition of epithelial polarity in the wing, eye, and epidermis. In mammals, PCP signaling has been shown to regulate cell movements and polarity in a variety of tissues. Here, we show that the murine Flamingo orthologues Celsr1-3 and the Prickle orthologues Prickle1, Prickle2, and Testin have dynamic patterns of expression during pregastrulation and gastrulation stages. Celsr1 is expressed in the anterior visceral endoderm and nascent mesoderm, Celsr2 and Celsr3 mark the prospective neuroectoderm, Prickle1 is expressed in the primitive streak and mesoderm, Prickle2 in the node, and Testin in the anterior visceral endoderm, the extraembryonic ectoderm, primitive streak, and mesoderm. Analysis of a gene-trap mutation in Testin indicates that this gene is not required for embryogenesis; therefore, other Prickle homologues may compensate for its function during development.     

携带hIL-2cDNA的逆转录病毒载体的构建及其在人肝癌细胞中的特异表达研究

将人白细胞介素２（ｈＩＬ-２）ｃＤＮＡ克隆到逆转录病毒载体ＭＮＳＭ的ＰＬ位点　，分别构建了转录受ＳＶ４０早期启动子和人甲胎蛋白增强子调控的重组逆转录病毒载体ＭＮＳＩ和ＭＮＳＩＡ。用脂质体转染法将ＭＮＳＩ和ＭＮＳＩＡ分别转导ＰＡ３１７包装细胞，测质粒转染率为（５～２０）×１０~(－３)克隆／μｇＤＮＡ·１０~６细胞，病毒感染率为（５．４～４５０）×１０~４ＣＦＵ／ｍｌ。重组病毒在４μｇ／ｍｌ ｐｏｌｙｂｒｅｎｅ存在条件下感染人肝癌细胞、肾癌细胞和黑色素瘤细胞，Ｎｅｏ~Ｒ克隆经Ｓｏｕｔｈｅｒｎｂｌｏｔ分析证明ｈＩＬ－２ｃＤＮＡ转入人肿瘤细胞并整合，　Ｒ　ＮＡ斑点杂交及ＩＬ－２活性表达分析证明，人甲胎蛋白增强子可促进异源启动子启动ｈＩＬ－２ｃＤ－ＮＡ在合成甲胎蛋白的人肝癌细胞中高效特异转录和表达。该研究对肝癌特异性免疫增强基因治疗有重要意义。     

Replication error phenotype and p53 gene mutation in lymphomas of mucosa-associated lymphoid tissue.

Low grade mucosa-associated lymphoid tissue (MALT) lymphomas commonly arise from a background of chronic inflammatory lesions and can transform into high grade tumors at a late stage. Because chronic inflammation is closely associated with genetic instability, which is one of the mechanisms leading to activation of oncogenes and inactivation of tumor suppressor genes, it is possible that genetic instability plays an important role in MALT lymphomagenesis. In this study, we have examined the frequency of replication error (RER+) phenotype, a newly defined manifestation of genetic instability, and its relationship to p53 mutations in 40 MALT lymphomas (16 high grade and 24 low grade). RER+ phenotype was detected in 21/40 (52.5%) MALT lymphomas (12/24, 50% in low grade; 9/16, 56.2% in high grade). Five of seven reactive lymphoid infiltrates adjacent to tumors also showed one microsatellite alteration, four of which were identified in the corresponding lymphoma lesions in the same patient. In five RER+ high grade lymphomas with low grade lesions, homogeneous and heterogeneous microsatellite alterations were observed between the two components. The same 40 cases were investigated for p53 gene mutations at exons 5 to 8 by PCR-SSCP and direct sequencing. p53 point mutations were found in 11 (27.5%) of the 40 cases. These mutations were statistically related to RER+ phenotype (P < 0.05). Our results demonstrate that the RER+ phenotype is a common genetic feature of MALT lymphomas. Genetic instability occurs throughout the spectrum of the lymphoma development and may be related to the accumulation of genetic aberrations such as p53 mutations. The observation of identical microsatellite alterations between the adjacent lymphoid infiltrates and their corresponding lymphomas provides genetic evidence for evolutionary link of the two lesions. The homogeneous and heterogeneous microsatellite alterations observed between low and high grade components indicate their clonal lineage and genetic diversity.     

Alpha-smooth muscle actin as a marker for soft tissue tumours: a comparison with desmin

The immunoreactivity of a range of vascular and non-vascular smooth muscle tumours, rhabdomyosarcomas, and non-myoid lesions has been examined with the use of a monoclonal antibody to smooth muscle-specific actin and the muscle intermediate filament, desmin. In all cases of smooth muscle-derived tumours, the alpha-actin antibody yielded superior results. Staining of the myofibroblasts of fibromatoses was also seen. In contrast to desmin, immunoreactivity was not exhibited by rhabdomyosarcomas. We propose that this monoclonal antibody to alpha-smooth muscle actin is a useful addition to the panel of reagents used for the characterization of soft tissue proliferations and tumours. The technical aspects of the application of this monoclonal antibody to immunohistochemistry are discussed.     

低温保存内生致热原对其致热活性的影响

本实验用家兔全血加精制大肠杆菌内毒素，体外培养提取粗制家兔内生致热原。给大鼠静脉注射复制发热模型，观察了不同温度保存和不同时间保存的ＥＰ对其致热活性的影响。结果表明：４℃保存３天，－４０℃保存３天，７天，３０天和１８０天的ＥＰ与４℃保存１天的ＥＰ比较，其发热第一时相发热峰值和１小时体温反应指数均无显著性差异（Ｐ＜０．０５）。发热第二时相△Ｔ和第二时相１小时ＴＲＩ，在４℃保存３天和－４０℃保存３天，     

Multiblock poly(ether-ester-amide)s based on polyamide-6 and poly(ethylene glycol), 2 Effect of composition and soft-segment length on the structure of poly(ether-ester-amide)s as revealed by X-ray scattering

Isotropic unannealed and annealed melt-pressed and quenched samples of segmented multiblock poly(ether-ester-amide)s based on polyamide-6 and poly(ethylene glycol)s (PEGs) of molecular weights 400 and 1000 with various hard/soft segment weight ratios were investigated. The effect of composition, segment length and annealing temperature on the crystal structure was studied by differential scanning calorimetry, wide-angle and small-angle X-ray scattering. In addition to the γ-phase, one of the unannealed samples having relatively long hard and soft segments exhibits a high amount of α-phase. This is assumed to be due to the high flexibility of the PEG segments, linking the polyamide blocks thus enhancing their mobility. The lack of hydrogen bonds between the PEG segments facilitates crystallization of the polyamide segments in the more perfect α-modification, which is the most pronounced in the above mentioned sample. Part of the α-phase transforms into the α-phase upon annealing in all copolymer samples studied, similarly to polyamide-6.