A preliminary in vitro study on the fabrication and tissue engineering applications of a novel chitosan bilayer material as a scaffold of human neofetal dermal fibroblasts

The bilayer structure of chitosan film and sponge was designed as a scaffold of skin tissue engineering and a dermis substitute. It was processed successively via the formation of a dense chitosan film by casting method and a porous chitosan sponge by lyophilization. The dry thickness of the film layer was 19.6 microm and that of the sponge layer was controlled at 60-80 microm. Porogens such as sodium chloride, glucose, and sucrose were used to create large pores of the chitosan sponge layer. Human neofetal dermal fibroblasts were seeded in the chitosan sponge layer and cultured for 4 weeks. It was found that the cells could grow and proliferate well in an extended shape on the flat bottom of large pores with 15-100 microm width and in spherical form on the rough pore walls or at the edges of micropores less than 5 microm. Fibroblasts after the culture could bind tightly with the sponge layer via newly formed extracellular matrices to give a living cell-matrix-chitosan composite. The bilayer chitosan material remained stable in shape and size during the cell culture. The results suggested that the bilayer chitosan material would be an alternative of collagen materials which was obviously contracted during cell culture.     

图书馆无形资产特性研究(上)

以无形资产为切入点．探讨图书馆在网络环境下与各类信息源及用户的辩证关系；以人为本的知识资本运营．无形资产的投入和知识产权保护比以往更加重要；提出社会无形资产概念：甄别信息资源专有权与公有权．论证图书馆社会角色；辨析图书馆知识管理．无形资产评估、立法理念。     

Delayed angiogenesis in aging rats and therapeutic effect of adenoviral gene transfer of VEGF

We have studied an age-related impairment in angiogenesis and evaluated the effect of overexpressing VEGF in this situation. Polyvinyl alcohol sponges were implanted subcutaneously into aged (24-month), adult (12-month), and young (2-month) rats. Blood vessel ingrowth and proliferative activity in the sponges were assessed by histology with immunostaining for von Willebrand's factor and proliferating cell nuclear antigen (PCNA), respectively. The percentage of total sponge area filled with ingrowing fibrovascular tissue was minimal in aged rats, intermediate in adult rats and highest in young rats. A similar pattern was observed for the total blood vessel numbers in the sponges from old to young animals. The percentage of total sponge endothelial cells (ECs) showing proliferative activity (PCNA positive) was lowest in the aged animals, intermediate in the adult rats and highest in the young rats. To further explore the mechanism of impaired angiogenesis in aged animals, we investigated and found a reduced level of endogenous VEGF protein expression in 12-month-old rats compared to that in 2-month-old rats. VEGF121 gene transfer significantly enhanced blood vessel and fibrovascular tissue ingrowth in adult/aged rats. Adenoviral-VEGF gene transfer also significantly stimulated EC proliferation in aged and adult rats. However, identical treatment failed to further stimulate the already more robust angiogenesis in young animals. The different angiogenic response in adult vs. young rats was not due to differences in gene transfer efficiency, since similar levels of human VEGF121 protein was detected in adult and young rats. Our results indicate that the decreased angiogenic response with aging is associated with reduced EC proliferation and reduced endogenous VEGF production. Adenoviral-VEGF121 gene transfer is effective in augmenting angiogenesis, particularly in older animals.     

IL-1β诱导体外培养的大鼠中脑黑质神经元c-jun表达

应用细胞原位杂交技术，观察经重组小鼠白细胞介素-19（IL-1β）处理后的体外培养的新生1d大鼠中脑黑质神经元c－jun基因的表达．结果显示，培养的黑质细胞多为酪氨酸羟化酶阳性神经元，IL-1β可诱导体外培养的黑质神经元c－junmRNA表达，高水平的表达出现在IL-1β处理后2～4h。说明IL－1β有兴奋黑质神经元的作用，并提示黑质神经元上可能存在IL－1β受体．     

IL-12p40-overexpressing immature dendritic cells induce T cell hyporesponsiveness in vitro but accelerate allograft rejection in vivo: role of NK cell activation and interferon-gamma production

Infusion of genetically modified dendritic cells (DC) expressing immunosuppressive molecules is a potential therapy for organ rejection. IL-12p70, a cytokine produced mainly by DC and macrophages, consists of two subunits, p40 and p35. IL-12p70 is an activator of T cells, while the IL-12p40 subunit serves as a natural antagonist for IL-12p70 action. The primary aim of this study was to evaluate the effect of IL-12p40 gene-modification on both the T-cell stimulatory activity of immature DC (imDC) and their ability to prolong cardiac allograft survival. IL-12p40 gene-modified imDC (DC-p40) exhibited a phenotype characteristic of imDC and displayed impaired T-cell allostimulatory ability in vitro. However, to our surprise, for murine vascularized heterotopic heart transplantation (HHT), administration of donor-derived DC-p40 7 days prior to transplantation did not prolong allograft survival but instead significantly exacerbated cardiac allograft rejection. Further study showed that DC-p40 augmented NK cell activity both in vitro and in vivo and enhanced interferon-gamma (IFN-gamma) production in vivo, which might be due to the increased IL-23 production by DC-p40. Our data suggested that although IL-12p40 gene-modified immature DC can induce T cell hyporesponsiveness in vitro, their ability to activate NK cells and induce IFN-gamma production counterbalances this, exacerbating cardiac allograft rejection. The unexpected effects of DC-p40 limit their value in promoting allograft survival in vivo and likely reflect the complexity of IL-12p40 biology.     

KOCH三角的解剖

本实验解剖了110例人心标本(成人70、儿童40)的Koch三角区,观察和测量了房室结的形态、大小、毗邻和标志。房间隔及冠状窦口上、下方均有肌束连于房室结。Todaro腱在儿童多全部为腱性;在成人,其后部为肌性。三角区的深面为左、右心房壁和室间隔顶所构成的锥形间隙,其内为进入房室结区的血管和神经。根据构成不同,可将三角区分为5个区,即前上角的纤维支架区和房室结区,其余部分自上向下分别为房间隔区、右房壁区和室间隔区。本文还讨论了这些形态结构的功能及外科意义。     

Identification of a new HLA-B*56 variant, B*5614

In this report, the novel allele B*5614 is presented. The allele was identified in a Chinese individual by sequence-based typing. HLA-B*5614 differs from B*5608 by a single nucleotide at position 277G-->C in exon 2. This results in an amino acid change from Gly to Arg at codon 93.     

Cocrystallization of an immunoglobulin light chain dimer with bis(dinitrophenyl) lysine: tandem binding of two ligands, one with and one without accompanying conformational changes in the protein

Previous studies showed that the Mcg dimer of immunoglobulin light chains bound bis(dinitrophenyl)lysine both in trigonal crystals and in solution. On prolonged storage in ammonium sulfate, mixtures of ligand and protein produced small trigonal cocrystals in low frequency. These crystals were nearly isomorphous with those of the unliganded dimer in which the subunits were covalently linked by an interchain disulfide bond. By difference Fourier analyses at 3.5 A resolution and subsequent crystallographic refinement, the cocrystals were found to contain molecules with two ligands aligned in tandem along the interface of the variable (V) domains of the protein. One ligand molecule adopted an almost fully extended conformation, with the epsilon-DNP ring situated near the floor, the alpha-carboxyl group directed toward the solvent at the entry, and the alpha-DNP ring outside the rim of the main cavity. As if architecturally designed, the ligand was located symmetrically between the two domains in an orientation that was compatible with both the unaltered structure of the cavity lining and with the known crystal packing interactions of neighboring protein molecules. The second ligand molecule in the cocrystal lodged in the deep pocket immediately under the floor of the main cavity. The ligand adopted a very compact conformation with the two DNP rings roughly antiparallel to each other. This molecule appeared to be semi-permanently sequestered in the pocket since it could not be dislodged by exhaustive perfusion with ammonium sulfate crystallizing media. Relative to its volume in the native dimer, the pocket was expanded to accommodate the oversized ligand. Within a single protein molecule, therefore, two types of binding of a flexible ligand were observed, one with and one without accompanying conformational changes in the protein. The number of cocrystals which could be produced was markedly increased if the interchain disulfide bond between the Mcg monomers was first reduced and alkylated.