基于超滤膜辅助的糖蛋白全N-连接糖链的富集和质谱解析

糖基化作为一种常见的蛋白质翻译后修饰,对蛋白质的空间结构、生物功能等具有重要的影响.解析糖蛋白糖链结构有助于更清楚地认识糖蛋白及其功能.本研究建立了一种基于超滤膜富集血清中糖蛋白全N-连接糖链,并利用质谱技术对糖链结构进行分析的方法.根据糖蛋白及其糖链结构之间的分子质量差异,利用Millipore公司的10 ku超滤膜富集血清糖蛋白上酶解(PNGase F)释放的全N-连接糖链,并使用MALDI-TOF/TOF-MS解析糖链结构.通过该技术可以从血清中富集并鉴定到23种独特的N-连接的糖链结构,并且利用二级质谱进行了结构确认.该方法可以被用于从大量生物样本中富集糖蛋白全N-连接糖链,可以达到快速、高通量地解析糖蛋白N-连接糖链的目的.     

科室全成本核算下公立医院责任成本体系研究

在当前科室全成本核算的基础上,建立责任成本体系,能够克服成本管理工作成本责任不明确的现象,对各科室的成本控制起到引导和激励作用,是全成本核算下进行成本控制的有效途径。责任成本体系的构建与实施包括：建立责任成本中心,分解成本责任,明确责任成本目标,组织责任成本核算,实施责任目标成本控制,并根据责任成本落实情况进行考评。     

基于挺水植物高光谱信息的再生水总氮含量估测——以北京市门城湖湿地公园为例

高光谱信息是探测植物体内氮素含量状况的重要手段,而植物体中的氮素与水体含氮量息息相关.本研究区为以再生水为主要补给水水源的北京门城湖湿地公园,通过获取区内典型的再生水氮净化挺水植物芦苇和香蒲叶片的高光谱数据,并在室内测定对应样点的水体总氮含量指标, 探讨基于典型湿地挺水植物高光谱数据对水体总氮进行遥感探测的可行性.采用4种高光谱参数(光谱指数、归一化差值指数、“三边”参数及吸收特征参数)分别建立一元线性模型、逐步多元回归模型和偏最小二乘模型,根据决定系数(R²)和均方根误差(RMSE)进行模型精度检验.结果表明: 逐步多元回归和偏最小二乘模型的预测精度高于一元线性模型. 3种模型对芦苇的拟合效果均优于香蒲.偏最小二乘模型对芦苇的拟合效果最优(R²=0.854,RMSE=0.647).500～700 nm是反映水氮含量的最佳波段范围,绿峰与红谷反射率的比值与水体总氮含量具有较强的相关性,尤其是吸收特征参数能够较好地预测水体总氮含量.     

正交试验优选超声提取芦笋总皂苷的工艺

目的:优选超声提取芦笋总皂苷的最佳工艺。方法:以高氯酸作为显色剂,用紫外分光光度法测定芦笋中总皂苷的含量,并以提取率为评价指标,采用单因素实验和正交试验优选最佳提取工艺。结果:芦笋总皂苷超声提取的最佳工艺为乙醇浓度70%,料液比1:15(W/V),超声时间50 min,超声温度40℃。结论:该提取工艺可行,为芦笋总皂苷的进一步研究提供了依据。     

Structure–activity relationships of the antimicrobial peptide gramicidin S and its analogs: Aqueous solubility,self-association,conformation, antimicrobial activity and interaction with model lipid membranes

GS10 [cyclo-(VKLdYPVKLdYP)] is a synthetic analog of the naturally occurring antimicrobial peptide gramicidin (GS) in which the two positively charged ornithine (Orn) residues are replaced by two positively charged lysine (Lys) residues and the two less polar aromatic phenylalanine (Phe) residues are replaced by the more polar tyrosine (Tyr) residues. In this study, we examine the effects of these seemingly conservative modifications to the parent GS molecule on the physical properties of the peptide, and on its interactions with lipid bilayer model and biological membranes, by a variety of biophysical techniques. We show that although GS10 retains the largely β-sheet conformation characteristic of GS, it is less structured in both water and membrane-mimetic solvents. GS10 is also more water soluble and less hydrophobic than GS, as predicted, and also exhibits a reduced tendency for self-association in aqueous solution. Surprisingly, GS10 associates more strongly with zwitterionic and anionic phospholipid bilayer model membranes than does GS, despite its greater water solubility, and the presence of anionic phospholipids and cholesterol (Chol) modestly reduces the association of both GS10 and GS to these model membranes. The strong partitioning of both peptides into lipid bilayers is driven by a large favorable entropy change opposed by a much smaller unfavorable enthalpy change. However, GS10 is also less potent than GS at inducing inverted cubic phases in phospholipid bilayer model membranes and at inhibiting the growth of the cell wall-less bacterium Acholeplasma laidlawii B. These results are discussed in terms of the comparative antibiotic and hemolytic activities of these peptides.     

Temperature dependence of diffusion in model and live cell membranes characterized by imaging fluorescence correlation spectroscopy

The organization of the plasma membrane is regulated by the dynamic equilibrium between the liquid ordered (L_o) and liquid disordered (L_d) phases. The abundance of the L_o phase is assumed to be a consequence of the interaction between cholesterol and the other lipids, which are otherwise in either the L_d or gel (S_o) phase. The characteristic lipid packing in these phases results in significant differences in their respective lateral dynamics. In this study, imaging total internal reflection fluorescence correlation spectroscopy (ITIR-FCS) is applied to monitor the diffusion within supported lipid bilayers (SLBs) as functions of temperature and composition. We show that the temperature dependence of membrane lateral diffusion, which is parameterized by the Arrhenius activation energy (E_Arr), can resolve the sub-resolution phase behavior of lipid mixtures. The FCS diffusion law, a novel membrane heterogeneity ruler implemented in ITIR-FCS, is applied to show that the domains in the S_o–L_d phase are static and large while they are small and dynamic in the L_o–L_d phase. Diffusion measurements and the subsequent FCS diffusion law analyses at different temperatures show that the modulation in membrane dynamics at high temperature (313 K) is a cumulative effect of domain melting and rigidity relaxation. Finally, we extend these studies to the plasma membranes of commonly used neuroblastoma, HeLa and fibroblast cells. The temperature dependence of membrane dynamics for neuroblastoma cells is significantly different from that of HeLa or fibroblast cells as the different cell types exhibit a high level of compositional heterogeneity.     

毒性多结节性甲状腺肿的手术术式探讨

目的:探讨毒性多结节性甲状腺肿的手术切除范围,为临床手术治疗毒性多结节性甲状腺肿提供理论依据。方法:收集2006年12月至2011年12月哈尔滨医科大学附属第一临床医学院普外科确诊且进行手术的52例双侧毒性多结节性甲状腺肿患者的临床资料,并按照术式分为次全切除组(24例)和近全/全切除组(28例)。术后通过病理检查观察其合并甲状腺癌的情况,临床观察其是否出现声音嘶哑(喉返神经损伤)和低钙血症(甲状旁腺损伤)情况,并随访患者甲状腺结节和(或)甲状腺功能亢进的复发情况。结果:次全切除组甲状腺癌的检出率为4.2%(1/24),近全/全切除组检出率为7.1%(2/28),两者比较差异无统计学意义(x2=0.02,P0.05);两组患者术后暂时性声音嘶哑发生率分别为4.2%(1/24)、3.6%(1/28),差异无统计学意义(x2=0.37,P0.05),术后暂时性低钙血症发生率分别为4.2%(1/24)、7.1%(2/28),差异亦无统计学意义(x2=0.02,P0.05)。近全/全切除组患者术后无甲状腺结节和(或)甲状腺功能亢进复发,次全切除组患者有5例复发,复发率为20.8%(5/24),两组比较差异有统计学意义(x2=4.28,P0.05)。结论:甲状腺近全/全切除术比次全切除术更能减少毒性多结节性甲状腺肿的复发。