正廿面体病毒衣壳参数的研究

本项研究从多学科的不同角度出发,对正廿面体病毒衣壳参数进行了深入研究.整理和开发出衣壳参数50多个,对其每一个参数的概念、含义、来源、参数值和参数间的关系作了明确的认定,并阐述了衣壳参数的理论意义及其应用价值.     

螺旋对称病毒衣壳参数的研究

本文从数学角度分析和研究了螺旋对称病毒衣壳参数、整理出衣壳参数２０多个,对每一个参数的概念、含义等给予了明确的认定。提示了参数间的关系,推导出了一些计算参数值的公式。     

单体在正二十面体衣壳中的聚集形式及其参数间的关系

单体(或称胥白亚单位)在正二十面体病毒衣壳中按一定数量“等价”和“准等价”的原则聚集成各种形式的寡聚体和壳粒。本文通过三角形坐标和病毒的构型分析了单体在衣壳上的各种排列、组合。并阐述了单体数与其它衣壳参数之间的关系。同时,对各种正二十面体病毒衣壳中的单体总数进行了计算。 1.单体在正二十面体衣壳中的聚集形式 单体是构成病毒衣壳较为简单的结构单位,它以     

家蚕传染性软化病病毒的冷冻电子显微镜三维重构

应用冷冻电子显微镜三维重构技术获得了家蚕传染性软化病病毒（Infectious flacherie virus,IFV）衣壳的三维立体结构.重构最终结果使用了5047个病毒粒子的数据.FSC曲线显示该重构结果的分辨率为18？.IFV的衣壳直径为302.4？,遵循拟T=3（P=3）二十面体对称.衣壳为单层,厚度15？,表面光滑致密,无明显突起或凹陷,无孔洞贯穿.将IFV衣壳结构与昆虫的类小RNA病毒-蟋蟀麻痹病毒（Cricket paralysis virus,CrPV）以及人小RNA病毒-人鼻病毒14（human rhinovirus14,HRV14）的衣壳进行比较,发现IFV衣壳结构与CrPV更为接近.与CrPV一样,IFV衣壳表面也缺少＂Rossmann峡谷＂.同时预测了IFV结构蛋白VP2和VP3的肽链折叠拓扑结构,并对亚基在衣壳表面的分布位置进行了推测.     

口蹄疫病毒热驯化及生物学特性分析

口蹄疫（Foot and mouth disease, FMD）是一种全球性的、感染偶蹄动物的传染病。病毒衣壳对温度，pH敏感，容易在疫苗生产及储存过程中裂解为免疫原性较低的五聚体，影响疫苗的质量。口蹄疫病毒（Foot and mouth disease virus, FMDV）对热敏感的机制研究对于疫苗抗原稳定性意义重大。本文通过循环热应激驯化方式诱导基因突变向耐热性发展，经噬斑纯化获得了驯化毒株M3,M9和M10。通过多序列比对分析发现驯化毒株P1区发生氨基酸突变，一步生长曲线表明驯化毒株氨基酸突变基本不影响病毒的复制，而驯化毒株相比野生型毒株衣壳耐热性有显著提高。驯化毒株M10单一位点突变（A1013T）增强衣壳稳定性，表明A1013T位点对于O型FMDV毒株衣壳耐热性的重要性，但机制仍待后期进一步阐明。该研究将为制备耐热性的FMD疫苗提供了理论依据。     

风疹病毒衣壳蛋白与宿主细胞相互作用蛋白的初步筛选及分析

风疹病毒(Rubella virus,RV)的衣壳蛋白(Capsid protein,CP)不仅是病毒颗粒的重要组成部分,而且还可以通过与宿主蛋白之间的相互作用来调控病毒的转录和复制.为了系统研究衣壳蛋白与宿主蛋白之间的相互作用关系,我们从RV基因组中克隆获得衣壳蛋白基因序列,将该序列导入含有eXact-6His串联亲和纯化标签的慢病毒表达载体中,并构建了稳定表达eXact-6His-Capsid融合蛋白的293T细胞系.通过eXact和6His标签的两次亲和纯化获得衣壳蛋白相互作用蛋白复合物,质谱检测并筛选后发现22个可能与衣壳蛋白相互作用的宿主蛋白.随后构建衣壳蛋白的相互作用网络并进行功能学分析,发现其相互作用蛋白主要参与病毒感染、RNA剪切、细胞凋亡及酶相关通路等过程.     

水痘一带状疱疹病毒分离株核衣壳的形态特征

本文用超薄切片电镜技术对水痘一带状疱疹病毒(VZV)分离株J_1的核衣壳进行了形态学研究。结果表明,在病毒感染后5小时即可观察到细胞核内大量的病毒核心相关颗粒和少量核衣壳。在细胞核内和细胞浆内均可见到病毒基质或毒浆结构。VZVJ_1株具有三种类型的核衣壳,命名为A型、B型、C型核衣壳。A型具有电子致密核心,B型的核心呈颗粒状,C型具有电子透明核心。三种核衣壳大小一致,直径75—100nm,核心为35—55nm。将VZV的核衣壳与疱疹病毒科其它成员作了比较分析,并对各种核衣壳在病毒成熟过程中的作用进行了探讨。     

衣壳修饰对病毒样颗粒稳定性及其免疫原性的影响

全球现有疫苗种类中，病毒样颗粒（Virus-like particles, VLPs）疫苗以其安全性和高效性而被广泛关注。VLPs是一种不含核酸的病毒蛋白衣壳，目前可根据不同需求设计目标衣壳蛋白序列并在不同的表达系统中构建生产。在疫苗设计环节，对VLPs衣壳蛋白进行合理设计和修饰，可大大增强VLPs的稳定性，尤其是提高衣壳组装过程及组装体的稳定性，间接影响VLPs的免疫原性，对提升VLPs疫苗的有效性和安全性有重要作用。近年来国内外研究表明影响VLPs衣壳组装过程的稳定性的基本因素是组装环境中的离子强度和pH值，而影响VLPs组装体稳定性及其免疫原性的主要因素有疏水性质和静电相互作用及糖基化水平等。疏水性对VLPs蛋白质结构的动态平衡和生物功能的发挥起关键作用，静电相互作用通过改变VLPs分子表面或内部的静电势能，影响VLPs衣壳内分子共价键的形成及其与外界环境的相互作用，糖基化修饰则利用自身修饰基团的生物学结构或其他功能性质影响整体VLPs颗粒的结构稳定性和免疫学功能。本文根据现阶段对VLPs的生产应用和结构的研究，综述了影响VLPs衣壳组装过程和组装体稳定性的主要因素，以及VLPs...     

草鱼呼肠孤病毒的三维重构与衣壳蛋白特性

草鱼呼肠孤病毒(grass carp reovirus, GCRV)为呼肠孤病毒科水生呼肠孤病毒属一新成员. 最新的基因组序列分析发现, GCRV与哺乳动物呼肠孤病毒(mammalian reovirus, MRV)具有高度的同源性. 为了解GCRV致病机理, 进行了分辨率达到17 Å的三维重构与衣壳蛋白特性研究. 结果表明: GCRV颗粒呈多层排列, 包括RNA核心与内壳层、中间层及外壳层. 由200个按T = 13对称排列的三聚体组成外衣壳, 其典型特征是在5次轴上出现三聚体缺失凹陷区, 暴露出中间层三聚体亚单位. 内壳层由120个单体组成, 按T = 1排列, 结构特点与呼肠孤病毒科成员内衣壳特征相一致. 衣壳蛋白电泳显示, GCRV颗粒含有7种蛋白(VP1-VP7)组分, 与MRV衣壳蛋白特性相近, 两者在衣壳结构组成上的相似性与基因组序列的高度同源性相吻合. 此结果对进一步研究GCRV与宿主细胞相互作用机理具有指导意义.     

水痘—带状疱疹病毒分离株核衣壳的形态特征

本文用超萍切片电镜技术对水痘－带状疱疹病毒（VZV）分离株J1的核衣壳进行了形态学研究。结果表明,在病毒感染后5小时即可观察到细胞核内大量的病毒核心相关颗粒和少量核衣壳。在细胞核内和细胞浆内均可见到病毒基质或毒浆结构。VZVJ1株具有三种类型的核衣壳,命名为A型、B型、C型核衣壳。A型具有电子致密核心,B型的核心呈颗粒状,C型具有电子透明核心。三种核衣壳大小一致,直径75－100nm,核心为35－55nm。将VZV的核衣壳与疱疹病毒科其它成员作了比较分析,并对各种核衣壳在病毒成熟过程中的作用进行了探讨。     

土壤水分对湿地松幼苗光合特征的影响

通过设置常规供水(CK)、轻度干旱(T1)、水饱和(T2)、水淹(T3)4个处理组,研究湿地松当年实生幼苗在不同土壤水分条件下的光合生理响应及叶绿素荧光特性。结果表明:不同水分处理对湿地松幼苗的叶片气体交换参数、水分利用效率(WUE)、光合色素、叶绿素荧光参数等指标有不同的影响;其中,T3的光合色素含量最低;T2、T3组的湿地松幼苗表现出较低的净光合速率(Pn)、电子传递速率(ETR)和PSⅡ光化学的量子效应(ΦPSⅡ),但与其他耐水淹植物相比,T3条件下的湿地松幼苗仍具有较高的Pn,说明湿地松幼苗具有较强的耐水淹能力;在T1条件下,湿地松幼苗具有较高的WUE和较低的蒸腾速率(Tr)、气孔导度(Gs)以对抗干旱的逆境,其Pn、PSⅡ最大光化学效率(Fv/Fm)、ETR和ΦPSII均有所下降,但仍能维持在相对正常的水平。研究证明,湿地松幼苗具有一定的耐淹耐旱特性,可运用于三峡库区消落带的植被重建。     

An optimized recipe for cloning of the polymerase chain reaction-amplified DNA inserts into plasmid vectors

This study compares a number of parameters that are important in the ligation of the polymerase chain reaction-amplified DNA inserts into plasmid vectors and their efficient transformation to bacterial cells. The parameters covered were: T4 polynucleotide kinase treatment followed by either the large fragment of E. coli DNA polymerase or T4 DNA polymerase reactions, the amount of T4 DNA ligase, temperature and duration of ligation, molar ratio of insert to vector as well as the total DNA concentration. The results show that the T4 polynucleotide kinase-treated group without further enzymatic manipulation, at an insert to vector ratio of 3:1 gave the highest recombination efficiency when 10 microg/ml DNA and 20 units T4 DNA ligase were applied for ligation for 12 h at 4 degrees C.     

高血压患者脉搏波参数与脉搏波传导速度的相关性研究

目的:探讨高血压患者脉搏波参数与脉搏波传导速度的相关性,为从脉图上辨识高血压病及脉搏波参数的拓展应用提供参考。方法:选择2012年6月至2013年6月在北京安贞医院和北京人民医院门诊和住院确诊的原发性高血压患者32例作为实验组,并招募健康成人志愿者29例作为对照组。利用中医四诊合参辅助诊疗仪与皮尺分别采集两组受试者的左侧寸口脉图信息和主动脉至桡动脉的血管长度,计算脉搏波参数及脉搏波传导速度,采用方差分析和皮尔逊简单相关的统计方法分析高血压患者不同的脉搏波参数与其脉搏波传导速度的相关性。结果:与对照组比较,实验组的PWV显著升高,有显著性差异(P0.05)。实验组H2/H1明显高于对照组(P0.05),但H4/H1、T1/T、T2/T比值均显著低于对照组(P0.05),差异均有显著性意义(P0.05)。高血压患者的H2/H1、T1/T、T2/T、H4/H1均与其PWV相关,其中H2/H1与PWV呈显著正相关(P0.05),T1/T、T2/T与PWV呈显著负相关(P0.05),H4/H1与PWV呈一般正相关(P0.05)。结论:高血压患者的脉搏波参数与脉搏波传导速度具有显著相关性,且潮波出现的幅值与脉搏波传导速度有显著正相关;脉搏波上升支和潮波的时值与脉搏波传导速度具有显著负相关,重搏波相对高度与脉搏波传导速度具有一般相关关系,因而可通过脉搏波参数的变化了解高血压患者血管弹性的状态。     

Assessment of compressive modulus, hydraulic permeability and matrix content of trypsin-treated nucleus pulposus using quantitative MRI

A clinical strength MRI and intact bovine caudal intervertebral discs were used to test the hypotheses that (1) mechanical loading and trypsin treatment induce changes in NMR parameters, mechanical properties and biochemical contents; and (2) mechanical properties are quantitatively related to NMR parameters. MRI acquisitions, confined compression stress-relaxation experiments, and biochemical assays were applied to determine the NMR parameters (relaxation times T1 and T2, magnetization transfer ratio (MTR) and diffusion trace (TrD)), mechanical properties (compressive modulus H(A0) and hydraulic permeability k(0)), and biochemical contents (H(2)O, proteoglycan and total collagen) of nucleus pulposus tissue from bovine caudal discs subjected to one of two injections and one of two mechanical loading conditions. Significant correlations were found between k(0) and T1 (r=0.75,p=0.03), T2 (r=0.78, p=0.02), and TrD (r=0.85, p=0.007). A trend was found between H(A0) and TrD (r=0.56, p=0.12). However, loading decreased these correlations (r=0.4, p=0.2). The significant effect of trypsin treatment on mechanical properties, but not on NMR parameters, may suggest that mechanical properties are more sensitive to the structural changes induced by trypsin treatment. The significant effect of loading on T1 and T2, but not on H(A0) or k(0), may suggest that NMR parameters are more sensitive to the changes in water content enhanced by loading. We conclude that MRI offers promise as a sensitive and non-invasive technique for describing alterations in material properties of intervertebral disc nucleus, and our results demonstrate that the hydraulic permeability correlated more strongly to the quantitative NMR parameters than did the compressive modulus; however, more studies are necessary to more precisely characterize these relationships.     

Evaluation of culture conditions for cellulase production by two Trichoderma reesei mutants under solid-state fermentation conditions

Response surface methodology (RSM) was used to evaluate the effects of fermentation parameters for cellulase production by Trichoderma reesei QM9414 and T. reesei MCG77 in solid-state fermentation using rice bran as substrate. Initial pH, moisture content and temperature were optimized using filter paper activity (FPA) as response. Statistical analysis of the results for T. reesei QM9414 showed that only moisture content had significant effect on cellulase activity and had a linear effect on enzyme activity (maximum enzyme activities were obtained at 70% moisture content). The results for T. reesei MCG77 showed that temperature and moisture content were the most significant parameters for cellulase activity. The optimum cellulase production was in the temperature range of 25-30 degrees C and moisture content between 55% and 70%. After the optimization, the FPA in T. reesei MCG77 was increased by 2.5 folds compared to that of T. reesei QM9414.     

Effect of ambient temperature on cardiovascular parameters in rats and mice: a comparative approach

Ambient air temperatures (T(a)) of <6 degrees C or >29 degrees C have been shown to induce large changes in arterial blood pressure and heart rate in homeotherms. The present study was designed to investigate whether small incremental changes in T(a), such as those found in typical laboratory settings, would have an impact on blood pressure and other cardiovascular parameters in mice and rats. We predicted that small decreases in T(a) would impact the cardiovascular parameters of mice more than rats due to the increased thermogenic demands resulting from a greater surface area-to-volume ratio in mice relative to rats. Cardiovascular parameters were measured with radiotelemetry in mice and rats that were housed in temperature-controlled environments. The animals were exposed to different T(a) every 72 h, beginning at 30 degrees C and incrementally decreasing by 4 degrees C at each time interval to 18 degrees C and then incrementally increasing back up to 30 degrees C. As T(a) decreased, mean blood pressure, heart rate, and pulse pressure increased significantly for both mice (1.6 mmHg/ degrees C, 14.4 beats.min(-1). degrees C(-1), and 0.8 mmHg/ degrees C, respectively) and rats (1.2 mmHg/ degrees C, 8.1 beats.min(-1). degrees C(-1), and 0.8 mmHg/ degrees C, respectively). Thus small changes in T(a) significantly impact the cardiovascular parameters of both rats and mice, with mice demonstrating a greater sensitivity to these T(a) changes.     

Ontogeny of growth hormone, prolactin, luteinizing hormone, and testosterone secretory patterns in the ram

The ontogenetic changes that occur in secretory patterns of growth hormone (GH), prolactin (Prl), luteinizing hormone (LH), and testosterone (T) in rams maintained in constant photoperiod were examined. Nine ram lambs were moved to individual pens in a controlled environment (12L: 12D cycle; 18-24 degrees C temperature) at 66 days of age. Blood samples were collected via indwelling cannulae at 15-min intervals for an 8-h period at 80, 136, 192, 248, and 304 days of age. Plasma concentrations of GH, Prl, LH, and T were quantitated and parameters of the secretory patterns determined. Mean concentration of GH tended to decline with age, probably because the amplitude of secretory peaks was significantly reduced with age. There were no age-associated changes in basal concentration of GH or incidence of GH peaks. There was an increase in Prl secretion (as estimated by mean concentration) at 136 and after 248 days of age. Significant age-associated changes occurred in all parameters of LH and T secretion. At the younger ages, testosterone concentrations were low and LH concentrations were elevated. At the older ages the relationship was reversed, with LH low and testosterone high. There were no significant correlations between frequency and magnitude of LH and T peaks. The significant correlations present among parameters of LH and T secretion were between basal concentration of LH and overall mean concentration and basal concentration of T. These results suggest that LH may not be the sole tropic stimulator of acute T secretion.     

Thyroid Hormone Influences Antioxidant Defense System in Adult Rat Brain

The objective of the current study was to find out whether thyroid hormone influences antioxidant defense parameters of rat brain. Several oxidative stress and antioxidant defense parameters of mitochondrial (MF) and post-mitochondrial (PMF) fractions of cerebral cortex (CC) of adult rats were compared among euthyroid (control), hypothyroid [6-n-propylthiouracil (PTU)-challenged], and hyperthyroid (T3-treatment to PTU-challenged rats) states. Oxidative stress parameters, such as thiobarbituric acid-reactive substances (TBA-RS) and protein carbonyl content (PC), in MF declined following PTU challenge in comparison to euthyroid rats. On the other hand, when PTU-challenged rats were treated with T3, a significant increase in the level of oxidative stress parameters in MF was recorded. Hydrogen peroxide content of MF as well as PMF of CC was elevated by PTU-challenge and brought to normal level by subsequent treatment of T3. Although mitochondrial glutathione (reduced or oxidized) status did not change following PTU challenge, a significant reduction in oxidized glutathione (GSSG) level was noticed in PMF following the treatment. T3 administration to PTU-challenged rats had no effect on mitochondrial glutathione status. Total and CN-resistant superoxide dismutase (SOD) activities in MF of CC augmented following PTU challenge. CN-resistant SOD activity did not change when PTU-challenged rats were treated with T3. Although CN-sensitive SOD activity of PMF remained unaltered in response to PTU challenge, its activity increased when PTU-challenged rats were treated with T3. Catalase activity in PMF of CC of PTU-challenged rats increased, whereas the activity was decreased when hypothyroid rats were treated with T3. Similarly, total and Se-dependent glutathione peroxidase (GPx) activities of MF increased following PTU challenge and reduced following administration of T3. Se-independent GPx activity of MF and PMF and glutathione reductase activity of PMF decreased following PTU challenge and did not change further when rats were treated with T3. On the other hand, glutathione S-transferase activity of MF and PMF of CC did not change following PTU challenge but decreased below detectable level following T3 treatment. Results of the current investigation suggest that antioxidant defense parameters of adult rat brain are considerably influenced by thyroid states of the body.     

Cadmium-induced inhibition of photosynthesis and long-term acclimation to cadmium stress in the hyperaccumulator Thlaspi caerulescens

Acclimation of hyperaccumulators to heavy metal-induced stress is crucial for phytoremediation and was investigated using the hyperaccumulator Thlaspi caerulescens and the nonaccumulators T. fendleri and T. ochroleucum. Spatially and spectrally resolved kinetics of in vivo absorbance and fluorescence were measured with a novel fluorescence kinetic microscope. At the beginning of growth on cadmium (Cd), all species suffered from toxicity, but T. caerulescens subsequently recovered completely. During stress, a few mesophyll cells in T. caerulescens became more inhibited and accumulated more Cd than the majority; this heterogeneity disappeared during acclimation. Chlorophyll fluorescence parameters related to photochemistry were more strongly affected by Cd stress than nonphotochemical parameters, and only photochemistry showed acclimation. Cd acclimation in T. caerulescens shows that part of its Cd tolerance is inducible and involves transient physiological heterogeneity as an emergency defence mechanism. Differential effects of Cd stress on photochemical vs nonphotochemical parameters indicate that Cd inhibits the photosynthetic light reactions more than the Calvin-Benson cycle. Differential spectral distribution of Cd effects on photochemical vs nonphotochemical quenching shows that Cd inhibits at least two different targets in/around photosystem II (PSII). Spectrally homogeneous maximal PSII efficiency (F(v)/F(m)) suggests that in healthy T. caerulescens all chlorophylls fluorescing at room temperature are PSII-associated.     

左旋精氨酸在冠脉搭桥术中心肌保护效果研究

目的：通过在心脏停搏液中添加适量左旋精氨酸来观察其在冠脉搭桥术中心肌保护效果。方法：选择2008年1月~2010年1月在我院行冠状动脉旁路移植术患者20例,随机分为2组,每组10例,对照组：常规心肌保护液组,不添加左旋精氨酸。实验组,心肌保护液中加入7．5gm左旋精氨酸。测患者术前（T1）、术后6小时（T2）、术后12小时（T3）、术后24小时（T4）、术后48小时（T5）血浆中TNF-α、IL-6、IL-8及cTnI含量。记录临床观察指标。结果：两组血浆TNF-α、IL．6、IL-8、cTnI浓度术前无统计学意义（P〉0．05）,术后各时点TNF-α、1L-6、IL．8、cTnI浓度显著升高且实验组均低于对照组（P〈0．05）。临床观察指标除血管活性药物应用情况实验组优于对照组（P〈0．05）外无明显差异。结论：在心脏停搏液中加入L-精氨酸,可有效保护缺血心肌,减轻心肌再灌注损伤程度。