小鼠硫酸乙酰肝素2-O-硫酸基转移酶Hs2st的生理功能和体外应用

硫酸乙酰肝素(HS)是由多个硫酸化结构的二糖单位重复形成的线型多糖,并以共价键形式与核心蛋白质连接形成硫酸乙酰肝素蛋白聚糖,而硫酸乙酰肝素2-O-硫酸基转移酶(Hs2st)为硫酸乙酰肝素多糖链硫酸化修饰的主要硫酸基转移酶,它将硫酸基团转移至L-艾杜糖残基的C2位。研究表明,HS的2-O-硫酸化对于HS与众多生长因子或受体进行相互作用是很重要的。缺乏功能性酶Hs2st的胚胎只能存活至出生前,临产时会由于无法形成完整的肾脏而死亡。这种致命性暗示了HS的2-O-硫酸化在小鼠胚胎发育过程中有着重要的作用。从形态学和分子水平上对Hs2st在小鼠胚胎发育过程中的重要性及其在肝素/HS合成过程中的作用进行了综述。     

肝素和硫酸乙酰肝素前体Heparosan的合成研究进展

肝素(Hep)和硫酸乙酰肝素(HS)是糖胺聚糖家族中的一类线性多糖,作为抗凝血药物广泛应用于临床中,在抗癌、抗病毒等方面也具有一定的作用。Heparosan是肝素和硫酸乙酰肝素共同的前体,决定着聚合物链的长度和糖单元主链的组成,也是其生物活性结构参数的决定因素。介绍了肝素/硫酸乙酰肝素的合成方法,综述了Heparosan的合成研究进展,并对生物工程领域合成Heparosan的前景进行了展望。     

派罗宁B褪色光度法测微量肝素

在pH 4.10的Britton-Robinson缓冲溶液中,肝素与派罗宁B形成离子缔合物,染料发生明显的褪色,体系吸光度的降低与肝素钠浓度成正比,肝素浓度在0～50 μg·(25 mL)-1范围内符合比耳定律.研究了表面活性剂和共存物质的影响,表明方法选择性好.用于肝素钠注射液效价的测定,结果令人满意.     

甲基紫共振瑞利散射法测微量肝素

基于肝素(Hep)对甲基紫(MV)共振瑞利散射的增强作用,建立了一种测定肝素的新方法。在pH值5.7-7.0的B-R缓冲溶液中,甲基紫与肝素反应形成缔合物,使溶液共振瑞利散射(RRS)增强,以658 nm处的灵敏度最高,它对肝素的检出限(3σ)为0.041 mg/L。研究了适宜的反应条件和影响因素,表明该方法灵敏、稳定、选择性好,用于肝素钠注射液的测定,回收率为96.4%~102.3%。     

溴代十六烷吡啶共振瑞利散射法测定肝素

基于肝素对溴代十六烷吡啶共振瑞利散射的增强作用,建立了一种测定肝素的新方法.在pH值为5.02～8.3的B-R缓冲溶液中,溴代十六烷吡啶与肝素反应形成缔合物,使溶液共振瑞利散射(RRs)增强,以475 nm处的灵敏度最高,它对肝素的检出限(3σ)为0.052 mg/L.研究了适宜的反应条件和影响因素,表明该方法灵敏、稳...     

内源性危险信号低分子量硫酸乙酰肝素的免疫佐剂作用

目的 研究内源性危险信号低分子量硫酸乙酰肝素(Heparan sulfate,HS)的免疫佐剂作用。方法按照HS的免疫剂量、免疫途径和免疫程序将ICR小鼠分组,同时设HBsAg对照组和铝佐剂对照组,分别于末次免疫后4、8、12、16、20和24周,采用ELISA法检测小鼠血清中的特异性IgG抗体水平;选择体液免疫效果最佳的剂量组免疫BALB/c小鼠,同时设空白对照组、抗原对照组和铝佐剂对照组,于末次免疫后8周,采用乳酸脱氢酶(LDH)法检测细胞杀伤活性。结果空白对照组小鼠在各检测时间点均未见IgG抗体产生。除第4组外,各实验组抗体滴度均在末次免疫后第8周达峰值,随着时间的推移,抗体水平呈下降趋势。第43组抗体水平升高快,峰值高,持续时间长;在实验剂量范围内,随着HS剂量的增加,针对HBsAg的特异性抗体水平也增加;HS的最佳剂量为100μg;皮下注射HS的免疫增强作用最佳,优于肌肉和鼻腔免疫;免疫程序对HS的佐剂作用影响不大。HS能诱导小鼠产生特异性的CTL细胞免疫效应,细胞杀伤活性显著高于空白对照组、抗原对照组及铝佐剂对照组(P﹤0.001)。结论 HS具有免疫佐剂作用,既能有效增强特异性体液免疫应答,又能显著诱导CTL细胞免疫效应,是一种优于铝佐剂的潜在人用疫苗佐剂。     

氨基酸影响尿石矿物草酸钙晶体形成的研究进展

综述了近年来在体外模拟及动物实验模型方面氨基酸对草酸钙（CaOxa）尿石形成作用的研究进展。讨论了氨基酸对CaOxa晶体成核、生长、聚集和固相转化的影响。     

硫酸乙酰肝素与氢氧化锌联合佐剂对HBsAg诱导小鼠免疫应答的影响

目的探讨硫酸乙酰肝素(Heparan sulfate,HS)与氢氧化锌联合佐剂对HBsAg诱导的小鼠体液免疫和细胞免疫应答的影响。方法将HS与氢氧化锌按不同剂量组合,与HBsAg(2μg)混合,免疫ICR小鼠,并设阴性对照、抗原对照、铝佐剂对照、单一HS及单一氢氧化锌对照组,共23组。分别于末次免疫后4、8、12、16、20、24周采血,分离血清,ELISA法检测小鼠血清中抗HBsAg抗体水平;选择体液免疫效果最佳的组免疫BALB/c小鼠,于免疫后8周,采用乳酸脱氢酶法检测细胞杀伤活性。结果阴性对照组在各时间点均未检测到IgG抗体,其余各组的抗体滴度均在末次免疫后第8周达峰值,随着时间的延长,抗体水平呈下降趋势。其中第23组(100μg HS+1.0 mg氢氧化锌,免疫2针)抗体水平最高,且持续时间较长,末次免疫后8周,其对HBsAg的体液免疫增强效应显著优于铝佐剂和HS单一佐剂(P<0.05),优于氢氧化锌单一佐剂,但差异无统计学意义(P>0.05)。联合佐剂能诱导产生特异性的CTL细胞免疫效应。结论 HS和氢氧化锌联合佐剂既能有效增强HBsAg诱导的小鼠特异性体液免疫应答,又能显著诱导CTL细胞免疫应答。     

肝素处理人工晶体在糖尿病白内障手术中的应用

目的 观察肝素表面处理的人工晶体(HeparinsurfacemodifidIOL,简称HSM-IOL)在糖尿病白内障超声乳化术中发挥的作用。方法 对2008年1月至2009年12月期间在我院进行诊治的120眼糖尿病白内障患眼进行随机分组,人工晶体经肝素处理过的组为实验组60眼,年龄23～78岁,男41例,女19例,人工晶体屈光度:+3D～+28D;未处理的为对照组60眼,年龄25～82岁,男37例,女23例,人工晶体屈光度+2D～+29D。结果 分析资料采用行X列资料的卡方检验,2组对比有显著性差异。对照组炎症反应重者较实验组明显增加,(P<0.05)。术后随访至少1年,比较2组术后矫正视力情况。肝素处理组在术后1、2周时的视力明显优于对照组,随着时间的推移,视力的差别逐渐缩小,至术后1年左右2组视力无显著差异(P>0.05)。结论 HSM-IOL可减轻糖尿病白内障患者的术后炎症反应。     

那屈肝素钙中N-NO的去除方法研究

分别采用氧化法、加热法、微波照射法、紫外照射法处理那屈肝素钙粗品,比较了不同方法对N-NO的去除效果;并进一步研究了紫外照射时间对那屈肝素钙产品关键指标的影响,进行了3批工艺验证和N-NO含量测定的方法学验证。结果表明,氧化法、加热法、微波照射法仅能去除50%左右的N-NO,而紫外照射20～60 min可以去除95%以上的N-NO,使那屈肝素钙产品符合欧洲药典(EP)标准要求(N-NO含量≤0.25μg·g^-1);紫外照射对那屈肝素钙产品的分子量、效价等关键指标无影响;方法学验证结果表明,热能分析仪适用于那屈肝素钙中N-NO含量的测定。     

Design and Synthesis of 6-O-Phosphorylated Heparan Sulfate Oligosaccharides to Inhibit Amyloid β Aggregation

Dysregulation of amyloidogenic proteins and their abnormal processing and deposition in tissues cause systemic and localized amyloidosis. Formation of amyloid β (Aβ) fibrils that deposit as amyloid plaques in Alzheimer's disease (AD) brains is an earliest pathological hallmark. The polysulfated heparan sulfate (HS)/heparin (HP) is one of the non-protein components of Aβ deposits that not only modulates Aβ aggregation, but also acts as a receptor for Aβ fibrils to mediate their cytotoxicity. Interfering with the interaction between HS/HP and Aβ could be a therapeutic strategy to arrest amyloidosis. Here we have synthesized the 6-O-phosphorylated HS/HP oligosaccharides and reported their competitive effects on the inhibition of HP-mediated Aβ fibril formation in vitro using a thioflavin T fluorescence assay and a tapping mode atomic force microscopy.     

Onset and persistence of changes in intestinal transport following dietary fat manipulation

In this study we determined the time-course for the onset and the loss of the effect of short-term feeding rats isocaloric semisynthetic diets containing a high content of saturated (HS) or polyunsaturated (HP) fatty acids on the jejunal and ileal uptake of medium- and long chain fatty acids, cholesterol and glucose. Animals were fed HP or HS for 3, 7 or 14 days; then the diet was switched to standard Purina^® rat chow for a further 3, 7 or 14 days. The uptake of medium chain fatty acids was unchanged. The differences between HP and HS in glucose uptake occurred within 3 days, but persisted for 14 days, whereas there were qualitative as well as quantitative changes in the pattern of lipid uptake: differences in uptake of stearic, oleic, linoleic and linolenic acids and cholesterol occurred after 7 days of feeding HP or HS. Jejunal uptake of linoleic acid was greater in HP than HS on day 7, but HS was greater than HP on day 14. The effect of diet on lipid uptake was similar in the jejunum and ileum. The altered uptake of stearic and oleic acids persisted after the rats were switched back to chow, whereas the uptake of the other nutrients became similar. Thus, (i) changes in dietary content of saturated and polyunsaturated fatty acids have early effects on intestinal transport function; (ii) some of these changes persist even when animals are returned to feeding on chow; and (iii) glucose transport is rapidly altered by dietary changes, whereas lipid uptake changes only after 7 days. We conclude that the transport function of the intestine is responsive to changes in dietary fatty acids.     

SiO2/S涂层与硫磷抑制剂对轻石脑油裂解结焦的影响

引言乙烯裂解炉辐射段炉管结焦是制约乙烯装置长周期运行的主要因素。裂解炉管的结焦会引起[1]:①管壁热阻增加,传热效率降低,裂解炉能耗增加;②炉管内径变小,流体压降增加,装置处理量减少;③炉管内壁渗碳,材料性能弱化;④周期性的清焦引起炉管热疲劳现象,而清焦过程中焦炭的     

硫酸软骨素A对草酸钙晶体生长和聚集的影响

用体外模拟方法研究了硫酸软骨素 A(简称 C4S)对草酸钙晶体矿化热力学的影响 ,并对纯水体系和 C4S- H2 O体系中形成的草酸钙晶体进行了物相分析与形貌观察。发现 C4S不但在热力学过程中有利于提高溶液中 Ca2 + 存在的浓度 ,而且能诱导一水草酸钙 ( COM)晶体的 ( 1 0 1 )晶面优先生长 ,并抑制 COM的二维生长和聚集。     

Factors Influencing Triacetone Triperoxide (TATP) and Diacetone Diperoxide (DADP) Formation: Part I

Conditions, which result in the formation of triacetone triperoxide (TATP) or diacetone diperoxide (DADP) from acetone and hydrogen peroxide (HP, were studied for the purposes of inhibiting the reaction. Reaction of HP with acetone precipitates either DADP or TATP, but the overall yield and amount of each was found to depend on (1) reaction temperature, (2) the molar ratio of acid to HP/acetone, (3) initial concentrations of reactants, and (4) length of reaction. Controlling molar ratios and concentrations of starting materials was complicated because both sulfuric acid and hydrogen peroxide were aqueous solutions. Temperature exercised great control over the reaction outcome. Holding all molar concentrations constant and raising the temperature from 5 to 25 °C showed an increase of DADP over TATP formation and a decrease in overall yield. At 25 °C a good yield of TATP was obtained if the HP to acetone ratio was kept between 0.5 : 1 and 2 : 1. At constant temperature and HP‐to‐acetone held at one‐to‐one ratio, acid‐to‐HP molar ratios between 0.10 : 1 and 1.2 : 1 produced good yield of TATP. Plotting the molality of HP vs. that of sulfuric acid revealed regions, in which relatively pure DADP or pure TATP could be obtained. In addition to varying reaction conditions, adulterants placed into acetone were tested to inhibit the formation of TATP. Because there is much speculation of the relative stability, sensitivity, including solvent wetting of crystals, and performance of DADP and TATP, standard tests (i.e. DSC, drop weight impact, and SSED) were performed.     

Possible Role of Crystal-Bearing Cells in Tomato Fertility and Formation of Seedless Fruits

Crystal-bearing cells or idioblasts, which deposit calcium oxalate, are located in various tissues and organs of many plant species. The functional significance of their formation is currently unclear. Idioblasts in the leaf parenchyma and the development of crystal-bearing cells in the anther tissues of transgenic tomato plants (Solanum lycopersicon L.), expressing the heterologous FeSOD gene and which showed a decrease in fertility, were studied by transmission and scanning electron microscopy. The amount of calcium oxalate crystals was found to increase significantly in the transgenic plants compared to the wild type (WT) ones in idioblasts and crystal-bearing cells of the upper part of the anther. At the same time, changes in the size and shape of the crystals and their location in anther organs were noted. It seems that the interruption in the break of the anther stomium in transgenic plants was associated with the formation and cell death regulation of a specialized group of crystal-bearing cells. This disturbance caused an increase in the pool of these cells and their localization in the upper part of the anther, where rupture is initiated. Perturbations were also noted in the lower part of the anther in transgenic plants, where the amount of calcium oxalate crystals in crystal-bearing cells was reduced that was accompanied by disturbances in the morphology of pollen grains. Thus, the induction of the formation of crystal-bearing cells and calcium oxalate crystals can have multidirectional effects, contributing to the regulation of oxalate metabolism in the generative and vegetative organs and preventing fertility when the ROS balance changes, in particular, during oxidative stresses accompanying most abiotic and biotic environmental factors.     

Apatite formation on titania–vaterite powders in simulated body fluid

Titania–hydroxyapatite composites were prepared by soaking compacts of a powder mixture consisting of crystalline titania and calcium carbonate (vaterite) to form apatite in simulated body fluid (SBF). The apatite crystal formed on compacts in SBF at 37 °C within 2 days. The apatite-forming ability of the mixtures was much higher than that of titania crystals such as anatase or rutile on their own. Calcium carbonate (vaterite), which has high solubility in the aqueous solution, plays an important role in the apatite formation; the dissolution is suggested to increase the supersaturation of the apatite in SBF. Formation of titanium hydroxide groups, which may induce the apatite formation, is drastically promoted on the powder-compacts by the soaking in SBF, independently of the structures of the titania crystals (anatase or rutile). The apatite formation on the compact of the titania–calcium carbonate (vaterite) powder mixture containing the anatase phase occurs in a shorter period than that on the one of titania (rutile)–calcium carbonate (vaterite). Crystalline titania (anatase phase) is suggested to be particularly effective in inducing the apatite nucleation.     

Chemical durability and microstructural analysis of glasses soaked in water and in biological fluids

A new glass, obtained from Bioglass^® BG45S5 original composition by substituting CaO with MgO, was produced and its chemical durability and microstructural characteristics were compared with that of Bioglass^®.The two glasses (labelled as BG45 and MG45) were soaked up to 4 weeks at physiological temperature in different solutions, i.e. bi-distilled water, Hank's Buffered Salt Solution 61200 (labelled as HBSS+), Hank's Buffered Salt Solution 14170 (labelled as HBSS−), and Kokubo's SBF. Moreover, the influence of either flat or flake surfaces was analysed for both glasses. Results showed that the chemical durability of a glass in saline at 37 °C, evaluated through pH and ICP-AES chemical analysis of the leached components, depended mainly on the chemical composition of the soaking solution. Moreover, the MG45 glass never exhibited hydroxyapatite crystal formation on its surface also after soaking in calcium-containing solutions. The apatite crystallisation and deposition mechanism, typical of a bioactive glass, was induced only if the glass itself contained calcium. The contemporaneous presence of calcium in the glass and in the soaking solution improved the reactivity of the glass, as apatite crystals nucleated in a shorter time and grew more quickly. As regards the morphology of the glass surface, rougher surfaces favoured the formation of hydroxyapatite crystals on glasses containing calcium.     

The kinetics of ettringite formation and dilatation in a blended cement with β-hemihydrate and anhydrite as calcium sulfate

The phase formation, heat of hydration and dilatation in a blended cement consisting of 50 wt.% calcium aluminate cement, 25 wt.% Portland cement and 25 wt.% calcium sulfate were studied (w/c=1). The calcium sulfate was β-hemihydrate, anhydrite and mixes of the two. Kinetic expressions describing the ettringite formation in the pastes with the pure calcium sulfates were found. Hydration reactions were suggested and the phase development was compared to the hydration heat by mass and heat balances. When the calcium sulfate was 75 and 50 wt.% β-hemihydrate, the systems behaved as a linear combination of the 100 and 0 wt.% blends. At 25 wt.%, the hydration kinetics differed from the other blends. With only β-hemihydrate, the last 50% of ettringite formation was accompanied by expansion, mainly caused by interaction of crystals growing radially on cement grains. In the paste with only anhydrite, ettringite crystals grew in solution and produced no expansion.