CDAP活化多糖制备5型肺炎链球菌荚膜多糖-破伤风类毒素结合疫苗

目的用1-氰基-4-二甲氨基-吡啶四氟硼酸(CDAP)代替溴化氰(CNBr)活化5型肺炎链球菌荚膜多糖,制备5型肺炎链球菌荚膜多糖-破伤风类毒素(TT)结合疫苗。方法将5型肺炎链球菌荚膜多糖溶液加CDAP活化,经ADH和缩合剂EDAC与破伤风类毒素进行偶联,经凝胶过滤柱层析纯化,得到5型肺炎链球菌多糖-TT结合物,并对其生化指标、血清学特异性、安全性及免疫原性进行检测。结果多糖-TT结合物的游离多糖含量与多糖的衍化率成反比;血清学特异性良好;经动物实验证明其安全性合格;具有良好的免疫原性,且游离多糖含量越低,免疫原性越强。结论用CDAP活化工艺制备的5型肺炎链球菌荚膜多糖-TT结合物适宜制备疫苗。     

6B型肺炎球菌荚膜多糖-破伤风类毒素结合疫苗的制备及其免疫原性

目的 制备6B型肺炎球菌荚膜多糖(6B-PNCPS)-破伤风类毒素蛋白(TT)结合疫苗,并研究其免疫原性。方法6B-PNCPS用溴化氰活化后与己二酰肼形成多糖-酰肼基衍生物,然后在蛋白活化剂碳二亚胺作用下将6B-PNCPS与TT进行共价结合。分别将其结合物及多糖免疫NIH小鼠,用ELISA检测小鼠血清中抗6B-PNCPS抗体。结果6B-PNCPS-TT结合物经凝胶色谱分析显示具有较6B-PNCPS更大的相对分子质量,多糖/蛋白比为1.42-1.66。结合物具有6B-PNCPS的血清学特异性,所诱生的抗6B-PNCPS特异性IgG抗体滴度与6B-PNCPS差异有显著意义。结论 用该法制备6B-PNCPS-TT结合疫苗,具有良好的免疫原性。     

1型和14型肺炎球菌多糖蛋白结合疫苗中糖链长度与免疫原性的相关性

目的探讨1型、14型肺炎球菌多糖蛋白结合疫苗中糖链长度和免疫原性的相关性,以解决多糖结合物难以纯化的问题。方法肺炎球菌荚膜多糖经过乙酸水解成为寡糖,与原糖采用相同的方法与破伤风类毒素结合,免疫小鼠后检测抗体水平,并与原糖结合物进行比较。结果小鼠体内均能产生较高的抗体水平,且具有免疫加强效应,寡糖结合物与原糖结合物的免疫原性差异无显著意义。结论1型、14型肺炎球菌的荚膜多糖经酸水解降解,不影响结合物的免疫原性。     

1-氰基-4-二甲基氨基吡啶·四氟化硼活化A群脑膜炎球菌多糖制备的结合疫苗的免疫原性及其工艺稳定性

目的分析1-氰基-4-二甲基氨基吡啶·四氟化硼(1-cyano-4-dimethylaminopyridinium tetrafluoroborate,CDAP)活化A群脑膜炎球菌多糖(group A meningococcal polysaccharide,Men APS)制备的A群脑膜炎球菌结合疫苗的免疫原性及其工艺稳定性。方法用CDAP活化多糖后,己二酰肼(adipic dihydrazide,ADH)衍化,制备多糖-酰肼基衍生物,在碳二亚胺[1-ethyl-3-(3-dimethylaminopmpyl)carbodiimide,EDAC]作用下,与TT偶联,制备A群脑膜炎球菌多糖结合疫苗原液(Men APSCDAP-TT),考察其免疫特性;将Men A PSCDAP-TT与C群脑膜炎球菌多糖结合疫苗原液混合,制备A、C群脑膜炎球菌结合疫苗(Men ACPSCDAP-TT),再与市售的采用溴化氰(CNBr)活化多糖制备的A、C群脑膜炎球菌结合疫苗(Men ACPSCNBr-TT)进行抗A群多糖Ig G抗体水平的比较。连续制备12批结合疫苗原液及9批结合疫苗,原液参考《中国药典》三部(2010版)进行各项检定,疫苗进行抗A群多糖Ig G抗体水平的检测。结果 Men APSCDAP-TT具有T细胞依赖性抗原特性;Men ACPSCDAP-TT免疫2次后产生的抗A群多糖Ig G抗体GMT明显高于市售疫苗免疫2次后水平,差异有统计学意义(P均0.01),也高于或相似于市售疫苗免疫3次后水平,但差异无统计学意义(P均0.05);免疫3次后产生的抗A群多糖Ig G抗体GMT仍高于或相似于市售疫苗,但差异无统计学意义(P0.05)。连续制备的12批结合疫苗原液,内毒素含量均低于10 EU/μg多糖,未检出游离蛋白,多糖/蛋白值、结合多糖含量、结合物分子大小分布、EDAC和ADH残留均符合A群脑膜炎球菌结合疫苗制造及检定规程(试行)YBS01112006的要求,主要检测指标及多糖回收率趋势分析基本在均数±2标准差内;9批Men ACPSCDAP-TT免疫后产生的抗A群多糖Ig G抗体GMT均在A群脑膜炎球菌多糖的60倍以上。结论经CDAP活化多糖后衍化再与载体蛋白结合制备的A群脑膜炎球菌结合疫苗具有良好的免疫原性,制备工艺稳定、可靠,为规模化生产奠定了基础。     

不同载体蛋白制备的A群脑膜炎球菌多糖结合物的免疫原性比较

目的比较不同载体蛋白(TT、DT和rEPA)制备的A群脑膜炎球菌多糖(GAMP)结合物的免疫原性。方法采用溴化氰(CNBr)活化多糖,以无水己二酸二肼(ADH)为连接剂,1-乙基-1-3-(3-二甲基氨基-丙基)-碳化二亚胺(EDAC)为偶联剂,制备结合物并免疫小鼠,检测小鼠血清中抗GAMP与抗载体蛋白抗体及抗GAMP抗体的杀菌活性。结果多糖衍生物、多糖-蛋白质结合物均具有GAMP抗原特异性;结合物免疫小鼠可诱生较单独多糖更高水平的血清抗GAMP IgG抗体和更强的体外杀菌活性,并能产生免疫记忆。结论3种载体蛋白制备的结合物均能提高多糖抗原的免疫原性。     

W135群脑膜炎球菌结合物的制备及其在小鼠体内的免疫原性

目的比较不同活化试剂、不同载体蛋白质及不同免疫程序对W135群脑膜炎球菌结合物在小鼠体内的免疫原性的影响。方法分别采用溴化氰(CNBr)和1-氰基-4-二甲基氨基吡啶-四氟硼酸盐(CDAP)为活化试剂,以己二酸二酰肼(ADH)为连接臂制备W135群脑膜炎球菌多糖(group W135 meningococcal polysaccharide,PSW135)衍生物;以碳二亚胺(EDAC)作为缩合剂,将多糖衍生物分别与破伤风类毒素(tetanus toxoid,TT)、白喉类毒素(diphtheria toxoid,DT)和重组铜绿假单胞菌外毒素A(recombinant Pseudomonas aeruginosa exotoxin A,r EPA)3种蛋白质共价结合,制备6种PSW135蛋白质结合物;比较4针免疫程序(0、2、4、8周)和3针免疫程序(0、4、8周)对结合物在小鼠体内免疫原性的影响。结果两种活化试剂均能对多糖进行有效活化,且不会破坏多糖的抗原性;制备的6种结合物在小鼠体内均能产生良好的免疫原性,且具有显著的剂次加强效应;采用间隔2周的3针免疫程序和2.5μg/只的免疫剂量,不同类型的活化试剂和载体蛋白质对结合物的免疫原性无显著影响,但以DT为载体蛋白质的结合物的免疫加强效应要弱于以TT和r EPA为载体的结合物;延长免疫间隔时间可显著提高结合物在小鼠体内的免疫原性。结论初步建立了适用于W135群脑膜炎球菌结合疫苗的结合工艺,并为结合物在小鼠体内的免疫原性研究提供了一种新的候选免疫程序。     

C群脑膜炎球菌多糖结合疫苗制备工艺的优化

目的优化C群脑膜炎球菌多糖-破伤风类毒素(Tetanus toxoid,TT)结合疫苗的制备工艺。方法分别采用衍化的降解多糖与TT结合、衍化TT与降解多糖结合和1-氰基-4-二甲基氨基吡啶.四氟化硼(CDAP)活化降解多糖后衍化再与TT结合的方法制备C群脑膜炎球菌多糖蛋白结合物PSAH-TT、PS-AHTT和PSCDAPAH-TT,并进行生化指标和抗原性检测,与溴化氰(CNBr)活化多糖衍化与TT的结合物PSCNBrAH-TT进行免疫原性比较,确定最适制备工艺,并制备2批结合疫苗,与市售疫苗进行免疫原性比较。结果 3种方法制备的多糖蛋白结合物生化指标存在差异,以PSCDAPAH-TT收率最高,且均保持了多糖的抗原性及免疫原性,并有免疫加强效应;PSCDAPAH-TT免疫2针后抗体GMT水平高于PSAH-TT和PS-AHTT,差异有统计学意义(P<0.05),3针后抗体GMT水平仍高于PSAH-TT和PS-AHTT,但差异无统计学意义(P>0.05),PSCDAPAH-TT免疫2针和3针后抗体GMT水平均高于PSCNBrAH-TT,且2针后差异有统计学意义(P<0.05),3针后差异也无统计学意义(P>0.05),但制备的2批PSCDAPAH-TT疫苗免疫2针和3针后的抗体GMT水平均明显高于市售疫苗,差异有统计学意义(P<0.05)。结论经CDAP活化降解多糖后衍化再与载体蛋白结合制备的疫苗具有较好的免疫原性。     

不同方法制备的1型肺炎球菌多糖-蛋白结合疫苗生化及免疫学特性比较

目的对两种方法制备1型肺炎球菌荚膜多糖-蛋白结合疫苗的生化及免疫学特性进行比较。方法分别采用溴化氰活化法与胺还原法制备结合物,并对其进行生化及免疫学检测。结果采用溴化氰活化法制备的结合物,较胺还原法具有较高的结合率及高分子结合物含量,免疫小鼠产生的抗体效价较胺还原法明显提高。结论采用溴化氰活化法制备1型肺炎球菌荚膜多糖-蛋白结合疫苗优于胺还原法。     

甲型副伤寒多糖-破伤风类毒素结合疫苗的制备及安全性和免疫原性

目的制备甲型副伤寒多糖-破伤风类毒素结合疫苗,并检测其安全性与免疫原性。方法副甲O-SP溶液加入CDAP活化,己二酰肼(ADH)衍化,在碳二亚胺(EDAC)作用下与破伤风类毒素(TT)偶联,反应物经柱层析纯化,制得多糖蛋白结合物,经质量检测后,进行安全性及免疫原性试验。结果所制备的结合物多糖蛋白比稳定在0.6~0.8之间,CL-4B检测Kd≤0.2时的回收率大于75%,高相对分子质量结合物含量不低于90%。免疫双扩散试验显示结合物与副甲家兔超免血清和TT抗血清均产生可见沉淀线。动物安全试验均合格。结合物免疫小鼠后,其血清副甲LPS抗体滴度显著增长,阳转率达到100%。结论用CDAP活化多糖制备的甲型副伤寒-破伤风类毒素结合疫苗质量稳定,安全可靠,且具有良好的免疫原性。     

Y群脑膜炎球菌多糖活化工艺的优化

目的优化Y群脑膜炎球菌多糖活化工艺,为A、C、W135、Y群脑膜炎球菌结合疫苗的研制奠定基础。方法分别以多糖衍化率和游离多糖含量为指标,按照三因素三水平正交试验,以不同的pH值、活化时间和活化剂加量对多糖进行活化后,与破伤风类毒素(TT)偶联,并经Sepharose4FF层析纯化后,对多糖-TT结合物进行各项生化检定、免疫原性检测及稳定性观察,确定最佳活化工艺,并对优化的工艺进行验证。结果以多糖衍化率为指标,可确定pH值和活化剂加量二因素对Y群脑膜炎球菌多糖的活化有显著影响(P<0.05),而以游离多糖为指标时,无法确定三因素对多糖的活化有显著影响(P>0.05),结合各项指标检测及稳定性观察结果 ,确定多糖活化最佳工艺为:在pH12条件下,向每mg多糖中加入等量活化剂,反应10min。采用优化的多糖活化工艺制备3批Y群脑膜炎球菌多糖-TT结合物,各项指标均符合多糖结合疫苗的常规质控标准。结论优化的多糖活化工艺可制备出游离多糖含量低、免疫原性高的Y群脑膜炎球菌多糖蛋白结合物,结果具有重复性。     

Study of the hydration of CaO powder by gas–solid reaction

Hydration of CaO powders by reaction with water vapor has been studied in isothermal and isobaric conditions. Experimental tests were performed within the temperature range of 70 °C–420 °C and with a water vapor pressure from 5 to 160 hPa by means of a thermogravimetric device. Two powders, exhibiting slight differences in their physical properties, were studied. However, for one of the powders and under some temperature and pressure conditions, the reaction is not complete. The difference of behavior between both CaO powders was interpreted by considering the effect of the morphological properties on the mechanism of growth of Ca(OH)₂.     

Quantification of Phospholipids Classes in Human Milk

Phospholipids are integral constituents of the milk fat globule membranes and they play a central role in infants’ immune and inflammatory responses. A methodology employing liquid chromatography coupled with evaporative light scattering detector has been optimized and validated to quantify the major phospholipids classes in human milk. Phospholipids were extracted using chloroform and methanol and separated on C18 column. Repeatability, intermediate reproducibility, and recovery values were calculated and a large sample set of human milk analyzed. In human milk, phospholipid classes were quantified at concentrations of 0.6 mg/100 g for phosphatidylinositol; 4.2 mg/100 g for phosphatidylethanolamine, 0.4 mg/100 g for phosphatidylserine, 2.8 mg/100 g for phosphatidylcholine, and 4.6 mg/100 g for sphingomyelin. Their relative standard deviation of repeatability and intermediate reproducibility values ranging between 0.8 and 13.4 % and between 2.4 and 25.7 %, respectively. The recovery values ranged between 67 and 112 %. Finally, the validated method was used to quantify phospholipid classes in human milk collected from 50 volunteers 4 weeks postpartum providing absolute content of these lipids in a relatively large cohort. The average content of total phospholipids was 23.8 mg/100 g that corresponds to an estimated mean intake of 140 mg phospholipids/day in a 4-week old infant when exclusively breast-fed.     

The influence of water removal techniques on the composition and microstructure of hardened cement pastes

The removal of water from hardened cement paste for analysis or to arrest ongoing hydration has been reported to affect the composition of hydrated phases and microstructure. The effect that arresting the hydration of hardened cement paste by replacing the pore water with acetone before drying, and by removing the water by freeze, vacuum and oven drying has on the hardened cement paste has been investigated. Two pastes were studied, a cemented iron hydroxide floc where a high proportion of ordinary Portland cement (OPC) had been replaced by pulverised fuel ash, and a pure hydrated OPC. The results showed that none of the water removal techniques caused any major deterioration in the composition and microstructure of the hardened cement pastes studied, but the pores appeared better preserved after arresting hydration using acetone quenching. Freeze drying appeared to cause more cracking of the microstructure than the other water removal techniques.     

Effect of plasma treatment of polymeric tape carriers on wetting behaviour of aqueous ceramic tape casting slurry

Due to environmental and health aspects, aqueous ceramic slurries are preferred to traditional organic solvent systems in tape casting. An important obstacle associated with the high surface energy of water is poor wetting of aqueous ceramic slurries on polymeric tape carriers. Therefore, we measured the contact angles of an aqueous epoxy-based ceramic slurry on polyethylene terephtalate (PET), polypropylene (PP), polymethyl methacrylate (PMMA), and aluminium-coated polyethylene terephtalate (PET-Al) films and investigated approaches to improving their wetting. We evaluated the effect of plasma treatment of the tape carrier surface on the wetting behaviour and compared it with the effect of adding non-ionic amphiphilic surfactants to the ceramic slurry. The treatment of the tape carrier surface by low-temperature plasma substantially improved the wetting behaviour of aqueous ceramic slurry. The lowest contact angle of 31° was obtained on the PET film. Although the addition of non-ionic surfactants improved both the wetting behaviour of the slurry and the detachment of the polymeric carrier from the ceramic tape even better than the plasma treatment of the carrier surface did, the plasma-treated carriers still present a useful alternative to the surfactants. In the case of the plasma-treated PET carrier the surfactants could be fully eliminated and potential drawbacks related to the use of surfactants could be prevented.     

The hydration of reactive cement-in-polymer dispersions studied by nuclear magnetic resonance

The behaviour of two novel cement-in-polymer (c/p) dispersions, namely cement-in-poly(vinyl acetate) and cement-in-poly(vinyl alcohol) upon exposure to water at room temperature was investigated by a combination of various NMR methods. The swelling, cracking, and the water ingress were monitored non-destructively using ¹H single point imaging. The hydration of the cement matrix was investigated using ²⁹Si NMR whilst ¹³C CPMAS NMR spectra allowed the quantification of the kinetics of the hydrolysis reaction of poly(vinyl acetate) into poly(vinyl alcohol). The polymer controls the rate of water ingress and swelling which in turn determines the behaviour of the c/p dispersions upon exposure to water. For the cement-in-poly(vinyl alcohol), the rates of water ingress and swelling are much faster than the hydration of the clinker whilst for the cement-in-poly(vinyl acetate) the slow rates of the two processes allow the formation of a cementious matrix which assures the stability of the sample.     

Effect of carbonation on the hydro-mechanical properties of Portland cements

We evaluate experimentally the effect of carbonation on the hydro-mechanical properties of Portland cement. Samples were carbonated at 90 °C and 28 MPa under wet supercritical CO₂. Two types of carbonation features were achieved, either the samples were homogeneously carbonated or they displayed sharp carbonation fronts. Using a tri-axial apparatus, the static elastic moduli and the mechanical strength were measured at in-situ pressure conditions (28 MPa) and showed a degradation of the mechanical properties of the samples where a carbonation front prevailed. Water and gas permeabilities were measured and showed that the samples with a carbonation front exhibit a stress sensitive permeability. P and S elastic wave velocities were measured to evaluate dynamic (ultrasonic range, 1 MHz) elastic moduli. The use of an effective medium theory approach enabled us to characterize the density and distribution of cracks within the samples. This approach outlines that the samples which developed a carbonation front were damaged.     

Assessment of the long-term stability of cementitious barriers of radioactive waste repositories by using digital-image-based microstructure generation and reactive transport modelling

Cement-based grout plays a significant role in the design and performance of nuclear waste repositories: used correctly, it can enhance their safety. However, the high water-to-binder ratios, which are required to meet the desired workability and injection ability at early age, lead to high porosity that may affect the durability of this material and undermine its long-term geochemical performance.In this paper, a new methodology is presented in order to help the process of mix design which best meets the compromise between these two conflicting requirements. It involves the combined use of the computer programs CEMHYD3D for the generation of digital-image-based microstructures and CrunchFlow, for the reactive transport calculations affecting the materials so simulated. This approach is exemplified with two grout types, namely, the so-called Standard mix 5/5, used in the upper parts of the structure, and the “low-pH” P308B, to be injected at higher depths.The results of the digital reconstruction of the mineralogical composition of the hardened paste are entirely logical, as the microstructures display high degrees of hydration, large porosities and low or nil contents of aluminium compounds.Diffusion of solutes in the pore solution was considered to be the dominant transport process. A single scenario was studied for both mix designs and their performances were compared. The reactive transport model adequately reproduces the process of decalcification of the C-S-H and the precipitation of calcite, which is corroborated by empirical observations. It was found that the evolution of the deterioration process is sensitive to the chemical composition of groundwater, its effects being more severe when grout is set under continuous exposure to poorly mineralized groundwater. Results obtained appear to indicate that a correct conceptualization of the problem was accomplished and support the assumption that, in absence of more reliable empirical data, it might constitute a useful tool to estimate the durability of cement-based structures.     

Experimental determination of the effective anionic charge density of polycarboxylate superplasticizers in cement pore solution

The specific anionic charge density of polycarboxylate superplasticizers can be determined experimentally by titration with a cationic polyelectrolyte. In this study, the anionic charge densities of several polycarboxylates based on methacrylate ester chemistry were measured in aqueous solution at pH 7 and 12.6, resp., and in cement pore solution. The anionic charge of the polycarboxylates increases with increasing pH value as a result of deprotonation of the carboxylate groups in the polymer backbone. Addition of Ca²⁺ ions generally causes a decrease of the anionic charge density. The reduction in anionic charge varies and depends on the architecture of the polycarboxylate. The effect results from the binding of calcium ions by the carboxylate groups, both through complexation and counter-ion condensation. Consequently, the effective anionic charge density of polycarboxylates in cement pore solution can differ significantly from the charge density which is calculated based on the chemical composition. Generally the -COO⁻ functionality may coordinate Ca²⁺ as a monodentate or bidentate ligand. The type of coordination depends on the steric accessibility of the carboxyl group. In PC molecules possessing high side chain density, the -COO⁻ group is shielded by the side chains and coordinates as bidentate ligand, producing a neutral Ca²⁺-PC complex. Accordingly, this type of PC shows almost no anionic charge anymore in cement pore solution. In PCs possessing high amount of -COO⁻, Ca²⁺ is coordinated monodentate, resulting in an anionic complex. Consequently, this type of PC shows significant anionic character in pore solution. Its adsorption behaviour is determined by a gain in enthalpy which derives from the electrostatic attraction between the PC and the surface of cement. This way, by utilizing the relatively simple method of charge titration, it is possible to assess the electrostatic attraction which, besides entropy gains, is the driving force behind the adsorption of polycarboxylates on the cement surface and thus determines their effectiveness as dispersing agent. The findings are generally applicable to other anionic admixtures used in cement.     

Design and function of novel superplasticizers for more durable high performance concrete (superplast project)

In this article we shall describe our quest and ultimate success in furthering our understanding of the action of superplasticizers on the rheology of cement and concrete. By specifically producing superplasticizers with varied architectures, we have been able to show the important structural features of the macromolecules that lead to a successful superplasticizer or water reducing agent. Both polycarboxylate and lignosulfonate polymers have been investigated. Using both non-reactive model MgO powders, three different types of cement blends, the adsorption behaviour and the effect on the rheological properties of these two important superplasticizer families have been used to further develop a conceptual model for superplasticizer — cement behaviour. This paper will deal mainly with the conceptual model, the materials and methods used to asses the polymer adsorption behaviour and rheological properties of the systems studied. We shall briefly describe the adsorption of the polymers onto the different surfaces and their influence on surface charge and rheology and the influence of the various ionic species found in cement pore solutions that may influence polymer-cement affinity. The key factors are shown to be the effective adsorbed polymer thickness and the induced surface charge which can be influenced by the polymer architecture, the pore solution composition and the initial particle surface charge.