三种关于建立家兔人工气道方法的评价

目的比较关于家兔三种人工气道（artificial airway,AA）建立方法,为实验中快速建立家兔人工气道选择较好的方法提供参考。方法选用新西兰大耳白兔共30只,随机均分为3组。分别采用气管切开法、经口明视气管插管法、经口盲探气管插管法建立人工气道,比较各组建立人工气道的时间,首次成功率及并发症发生情况。结果经口盲探气管插管法建立人工气道的时间明显短于经口明视气管插管法和气管切开法,首次成功率由高到低依次是气管切开法、经口盲探气管插管法、经口明视气管插管法。经口盲探气管插管组并发症发生率最低,为（10±5）%,气管切开组和经口明视气管插管组并发症发生率分别为（20±10）%,（30±10）%。结论经口盲探气管插管是现阶段建立家兔人工气道时值得优先考虑的方法,简便易行、可操作性强,成功率高。     

Diverse energetic effects of charge reversal mutations of poxvirus topoisomerase IB

A key aspect of the reaction mechanism of type IB topoisomerases is the controlled unwinding of DNA supercoils while the enzyme is transiently bound to one strand of the DNA duplex via a phosphotyrosyl linkage. In this complex, the mobile segment of the bound DNA downstream from the site of cleavage must rotate around the helical axis, requiring that interactions with the enzyme must break and re-form multiple times during the course of removing supercoils. A crystal structure of variola virus type IB topoisomerase (vTopo) bound to DNA shows several positively charged side chains that interact with the downstream mobile and upstream rigid segments, suggesting that these groups may play a role in catalysis, including the processive unwinding of supercoils. We have mutated three such residues, R67, K35, and K271, to Ala and Glu and determined the energetic effects of these mutations at each point along the reaction coordinate of vTopo. R67 interacts with a phosphate group in the rigid DNA segment across from the site of DNA strand cleavage. The ~30-fold damaging effects of the R67A and R67E mutations were primarily on the phosphoryl transfer step, with little effect on enzyme-DNA binding, or the processivity of supercoil unwinding. Removal of the K35 interaction shows mutational effects similar to those of R67, even though this residue interacts with the mobile segment 3 bp from the cleavage site. The two mutations of K271, which interacts with the mobile region even further from the site of covalent linkage, show significant effects not only on phosphoryl transfer but also on downstream DNA strand positioning. Moreover, supercoil unwinding measurements indicate that the K271A and K271E mutations increase the average number of supercoils that are removed during the lifetime of the covalent complex, enhancing the processivity of supercoil unwinding. These measurements support the proposal that the processivity of supercoil unwinding can be regulated by electrostatic interactions between the enzyme and the mobile DNA phosphate backbone.     

Modulation of retroviral restriction and proteasome inhibitor-resistant turnover by changes in the TRIM5alpha B-box 2 domain

An intact B-box 2 domain is essential for the antiretroviral activity of TRIM5alpha. We modeled the structure of the B-box 2 domain of TRIM5alpha based on the existing three-dimensional structure of the B-box 2 domain of human TRIM29. Using this model, we altered the residues predicted to be exposed on the surface of this globular structure. Most of the alanine substitutions in these residues exerted little effect on the antiretroviral activity of human TRIM5alphahu or rhesus monkey TRIM5alpharh. However, alteration of arginine 119 of TRIM5alphahu or the corresponding arginine 121 of TRIM5alpharh diminished the abilities of the proteins to restrict retroviral infection without affecting trimerization or recognition of the viral capsid. The abilities of these functionally defective TRIM5alpha proteins to accelerate the uncoating of the targeted retroviral capsid were abolished. Removal of the positively charged side chain from B-box 2 arginines 119/120/121 resulted in diminished proteasome-independent turnover of TRIM5alpha and the related restriction factor TRIMCyp. However, testing of an array of mutants revealed that the rapid turnover and retroviral restriction functions of this B-box 2 region are separable.     

Post‐activation treatment with demecolcine improves development of somatic cell nuclear transfer embryos in pigs by modifying the remodeling of donor nuclei

The objective of this study was to examine the effect of cytochalasin B (CB) and/or demecolcine (Dc) on the remodeling of donor nuclei, nuclear ploidy, and development of somatic cell nuclear transfer (SCNT) and parthenogenetic (PA) pig embryos. SCNT and PA oocytes were either untreated (control), or treated with CB, Dc, or both CB and Dc after electric activation, and then cultured or transferred to surrogates. In SCNT, blastocyst formation was higher after treatment with CB and/or Dc (26–28%) than in the controls (16%). The number of oocytes that formed a single pronucleus (PN) was higher after treatment with Dc (86%) and CB + Dc (86%) than under control conditions (44%) or after treatment with CB (63%). In PA, blastocyst formation was higher after CB treatment (47%) than under control conditions (28%), while the formation of a single PN was higher after treatment with Dc (88%) and CB + Dc (84%) compared to controls (34%). The rate of formation of diploid embryos was higher after treatment with Dc and CB + Dc than under control conditions. Dc treatment resulted in a farrowing rate of 50% with 1.1% production efficiency, while controls showed a farrowing rate of 37.5% and a production efficiency of 0.7%. The results of our study demonstrate that post‐activation treatment with Dc improves preimplantation development and supports normal in vivo development of SCNT pig embryos, probably because Dc induces formation of a single PN and this leads to normal nuclear ploidy. Mol. Reprod. Dev. 76: 611–619, 2009. © 2008 Wiley‐Liss, Inc.     

大鼠胫骨近端骨骺损伤后骨桥形成分子机制的研究

利用胫骨近端干骺端骨骺损伤的大鼠动物模型,研究骨桥形成的分子病理机制.通过Alcian blue染色观察损伤模型的建立、损伤愈合过程以及骨桥形成情况.采用Tunel试剂盒原位细胞凋亡检测,了解损伤区及周围细胞凋亡情况.利用免疫组织化学及原位杂交实验,观察损伤区周围软骨细胞改变,检测损伤区是否有软骨细胞生成,检测刀Ihh以及Ptch1表达阳性细胞.发现骨骺损伤骨桥形成过程中,完全损伤区中心没有软骨细胞特异的因子Col2al和ColX以及删Ihh和Ptch1的表达,但是完全损伤区和周围正常软骨交界间存在次损伤软骨区,存在软骨细胞凋亡,有Col X的表达,vimentin检测发现,在此区和周围正常软骨间有正常肥大区软骨细胞异常分化而来的成纤维样细胞并形成软骨外膜样结构,次损伤区和软骨外膜结构逐渐被骨桥替代,在此过程中软骨外膜样结构存在Collal、Ptch1和Ihh的表达,提示Ihh可能参与骨桥形成过程.提出骨桥形成过程中损伤中心区域存在膜内化骨,边缘区域存在软骨化骨作用机制.     

A Scheme to Optimize Flow Routing and Polling Switch Selection of Software Defined Networks

This paper aims at minimizing the communication cost for collecting flow information in Software Defined Networks (SDN). Since flow-based information collecting method requires too much communication cost, and switch-based method proposed recently cannot benefit from controlling flow routing, jointly optimize flow routing and polling switch selection is proposed to reduce the communication cost. To this end, joint optimization problem is formulated as an Integer Linear Programming (ILP) model firstly. Since the ILP model is intractable in large size network, we also design an optimal algorithm for the multi-rooted tree topology and an efficient heuristic algorithm for general topology. According to extensive simulations, it is found that our method can save up to 55.76% communication cost compared with the state-of-the-art switch-based scheme.     

A high-sensitive and fast-fabricated glucose biosensor based on Prussian blue/topological insulator Bi(2)Se(3) hybrid film

A novel and fast-fabricated Prussian blue (PB)/topological insulator Bi(2)Se(3) hybrid film has been prepared by coelectrodeposition technique. Taking advantages of topological insulator in possessing exotic metallic surface states with bulk insulating gap, Prussian blue nanoparticles in the hybrid film have smaller size as well as more compact structure, showing excellent pH stability even in the alkalescent solution of pH 8.0. Based on the Laviron theory, the electron transfer rate constant of PB/Bi(2)Se(3) hybrid film modified electrode was calculated to be 4.05±0.49s(-1), a relatively big value which may be in favor of establishing a high-sensitive biosensor. An amperometric glucose biosensor was then fabricated by immobilizing glucose oxidase (GOD) on the hybrid film. Under the optimal conditions, a wide linear range extending over 3 orders of magnitude of glucose concentrations (1.0×10(-5)-1.1×10(-2)M) was obtained with a high sensitivity of 24.55μAmM(-1) cm(-2). The detection limit was estimated for 3.8μM defined from a signal/noise of 3. Furthermore, the resulting biosensor was applied to detect the blood sugar in human serum samples without any pretreatment, and the results were comparatively in agreement with the clinical assay.     

A Streptococcus iniae DNA vaccine delivered by a live attenuated Edwardsiella tarda via natural infection induces cross‐genus protection

Edwardsiella tarda and Streptococcus iniae are important fish pathogens. We have reported previously a live E. tarda vaccine based on the attenuated strain TX5RM and a S. iniae DNA vaccine based on the antigen Sia10. In this study, we examined the possibility of constructing a cross‐genus vaccine by taking advantage of the residual infectivity of TX5RM and using it as a carrier host for the natural delivery of a S. iniae DNA vaccine. For this purpose, the recombinant TX5RM, TX5RMS10, was created, which harbours and retains stably the DNA vaccine plasmid pCS10 that expresses Sia10. When flounder were vaccinated with TX5RMS10 via oral and immersion routes, TX5RMS10 was detected in multiple tissues within 12–14 days postvaccination (p.v.). At 7 and 14 days p.v., expression of the DNA vaccine was detected in spleen, kidney and liver. Following E. tarda and S. iniae challenge at one and 2 months p.v., the vaccinated fish exhibited relative per cent survival rates of 69–83%. Immunological analysis indicated that TX5RMS10‐vaccinated fish produced specific serum antibodies and exhibited enhanced expression of a wide range of immune genes.     

Heterogeneous genetic invasions of three insecticide resistance mutations in Indo‐Pacific populations of Aedes aegypti (L.)

Nations throughout the Indo‐Pacific region use pyrethroid insecticides to control Aedes aegypti, the mosquito vector of dengue, often without knowledge of pyrethroid resistance status of the pest or origin of resistance. Two mutations (V1016G + F1534C) in the sodium channel gene (Vssc) of Ae. aegypti modify ion channel function and cause target‐site resistance to pyrethroid insecticides, with a third mutation (S989P) having a potential additive effect. Of 27 possible genotypes involving these mutations, some allelic combinations are never seen whereas others predominate. Here, five allelic combinations common in Ae. aegypti from the Indo‐Pacific region are described and their geographical distributions investigated using genome‐wide SNP markers. We tested the hypothesis that resistance allele combinations evolved de novo in populations versus the alternative that dispersal of Ae. aegypti between populations facilitated genetic invasions of allele combinations. We used latent factor mixed‐models to detect SNPs throughout the genome that showed structuring in line with resistance allele combinations and compared variation at SNPs within the Vssc gene with genome‐wide variation. Mixed‐models detected an array of SNPs linked to resistance allele combinations, all located within or in close proximity to the Vssc gene. Variation at SNPs within the Vssc gene was structured by resistance profile, whereas genome‐wide SNPs were structured by population. These results demonstrate that alleles near to resistance mutations have been transferred between populations via linked selection. This indicates that genetic invasions have contributed to the widespread occurrence of Vssc allele combinations in Ae. aegypti in the Indo‐Pacific region, pointing to undocumented mosquito invasions between countries.