生物医用天然多糖自愈合凝胶研究进展

自愈合凝胶作为一种新型智能高分子材料,因其在软材料修复、药物载体及组织工程等领域已显现的卓越性能,近年成为医用创新材料研究的重要热点之一。但目前自愈合凝胶材料尚存在生物相容性差、原料自身毒副损害作用较大等诸多问题,容易对人体造成慢性毒副作用。因此,为了预防以及改善这些问题,以天然产物为原料的高生物相容、低毒害作用的自愈合凝胶的研究在此领域具有巨大潜力和重要意义。本文从生物医用角度对目前天然多糖自愈合凝胶制备的研究进展与成果进行较为全面的评述,并提出了天然多糖自愈合凝胶未来深入研究中亟待解决的问题,为天然多糖自愈合凝胶的生物学及生物医药领域应用研究提供有益的参考。     

微生物多糖透明质酸生物医用水凝胶研究

微生物多糖透明质酸水凝胶作为具有多样生物活性非人工合成高分子材料,因其在药物缓释、组织修复等领域的出色性能,近年已成为天然生物医用材料研究热点之一。但透明质酸水凝胶尚存在降解时间较短、力学性能不佳等缺陷,而无法实现对不同类型组织的良好修复。因此,为赋予透明质酸更优材料应用性能及生物功能,以透明质酸为原料制备具有卓越力学性能、适当降解速率的水凝胶研究具有重要理论和实践意义。本文从生物医用角度对近年采用化学交联及物理作用制备改性透明质酸水凝胶的研究进行综述,提出用于组织工程领域透明质酸水凝胶医用材料未来发展中亟待解决的问题,进而为透明质酸水凝胶应用研究提供有价值的参考。     

动植物多糖对人体的作用及含量测定

动植物多糖对人体的作用及含量测定上海市卫生防疫站（２００３３５）杨滨李英多糖是重要的生物高分子化合物。多糖存在于自然界中的高等植物、细菌、真菌、藻类及动物体内。随着对多糖活性的深入了解，以及人们对各种天然药品、天然食品的推崇，多糖以其无毒、无副作用，...     

生物可降解高分子材料——Novosorb

医用生物高分子材料目前成为科研机构的主要研究领域。人们一直在寻找并研发低成本、具有生物兼容性、可吸收性的医用高分子材料。     

解析壳聚糖生物医用材料的应用

随着科学技术的研究不断深入,壳聚糖作为生物医用材料的应用越来越广泛。壳聚糖（cS）是一种半合成高分子氨基多糖,具有独特的化学结构,主要存在于动植物虾蟹壳中,由于对人体无毒、无刺激、无致敏、生物可降解等特性,是FDA认可的一类生物降解材料并且已广泛应用于生物医用材料领域。该文简要介绍了壳聚糖在医药方面的应用,供大家参考。     

生物医用高分子材料与现代医学

随着人民生活水平的提高和现代医学的发展,生物医用高分子材料日益重要,在医疗费用中的比重也十分突出.医用高分子材料具有广泛的用途,相关材料在生物相容性等方面也有严格要求,本文对此作了概括和分类,并对其最新进展做了简单介绍.     

生物医用高分子材料在医疗中的应用

本文论述了生物医用高分子材料的发展概况，重点介绍了硅橡胶、聚氯乙烯、聚氨酯等生物医用高分子材料的特性及其在医疗器械中的应用。     

软组织修复医用材料及产品的研究进展

软组织是人体内一类不可或缺的组织,它有着保护机体免遭外界物理化学因素或生物因素侵害的重要作用。轻度软组织损伤能够自愈,但重度软组织损伤可能需要进行相关治疗。天然高分子材料（如壳聚糖、透明质酸、胶原蛋白）与合成高分子材料（如聚乙二醇、聚乳酸）具有良好的生物相容性、生物降解性与低毒性,用于软组织修复,可起到抗菌、止血与促进创面愈合的作用,通过改性或制备复合材料的方法可提升相关性能。常用的软组织修复产品有伤口敷料、生物补片、医用组织黏合剂、组织工程支架等。该研究主要对包括壳聚糖、透明质酸、胶原蛋白、聚乙二醇和聚乳酸在内的各类软组织修复医用材料的性质、作用机制及产品的应用进行介绍,并对软组织修复医用材料及产品的应用前景进行展望。     

等离子体表面改性技术在医用高分子材料领域的应用

对于医用高分子材料而言,材料的生物相容性至关重要;而在不改变材料本体性质的前提下实施表面改性是一种重要而相对实用的手段之一.本文介绍了等离子体技术,对于该技术用于表面改性的基本途径和目前在生物医用高分子材料方面的主要用途进行了综述,尤其是总结了等离子体表面改性技术在提高医用高分子材料生物相容性方面的研究进展.     

多糖的分子修饰及其降血糖作用的研究进展

多糖是一种重要的生物高分子物质,降血糖是其重要生物功能之一。研究表明,多糖基团对其降血糖活性起重要作用,故可通过修饰多糖分子结构来影响其降血糖活性。该文阐述多糖的硫酸化、脱硫酸化、乙酰化等分子修饰方法及修饰后的多糖对降血糖活性的影响,并展望多糖分子修饰的应用前景。     

Preparation and characterization of an immunogenic meningococcal group A conjugate vaccine for use in Africa

Periodic epidemics of group A meningococcal (Mn A) meningitis continue to occur in sub-Saharan Africa. For its prevention, a Mn A polysaccharide (PS)–tetanus toxoid (TT) conjugate vaccine was developed using reductive amination of polysaccharide aldehydes and toxoid hydrazides. In mouse immunization studies, a schedule of three bi-weekly s.c. immunizations of 0.1 or 1 μg of the conjugate (PS content) without an adjuvant induced serum antibody levels of >10,000 units/mL measured by enzyme-linked immunosorbent assay (ELISA) as compared to ∼100 units/mL in PS control mice. The elicited antibodies were active in bactericidal assays using either baby rabbit or human complement (titers >1500 compared to ∼200 for the PS control group). The synthesis process is reproducible and scalable, and has been successfully used for manufacturing a Mn A PS–TT conjugate vaccine based on a paradigm of shared manufacturing with transfer of new technology [Jodar L, LaForce FM, Ceccarini C, Aguado T, Granoff DM. Meningococcal conjugate vaccine for Africa: a model for development of new vaccine for the poorest countries. Lancet 2003, 361:1092–4]. A phase 1 clinical trial of the manufactured Men A–TT conjugate vaccine has been successfully carried out in adults in India, and a phase 2 clinical trial in young children is currently underway in Africa.     

Safety and immunogenicity of the 23-valent pneumococcal polysaccharide vaccine at 12 months of age,following one,two, or three doses of the 7-valent pneumococcal conjugate vaccine in infancy

Fijian infants aged 6 weeks were stratified by ethnicity and randomized to receive 0, 1, 2, or 3 PCV-7 doses with or without the 23-valent pneumococcal polysaccharide vaccine (PPV-23) at 12 months. Strong booster effects for all 7 PCV-7 serotypes were elicited, and for 4/7 serotypes these responses were highest in the single PCV-7 group. There were fourfold rises in GMC for all non-PCV-7 serotypes. By 17 months the PPV-23 group still had significantly higher GMC (each p < 0.001) for all serotypes. The PPV-23 was well tolerated and induced excellent responses for all serotypes which were greatest in the single PCV-7 group.     

Molecular shape and immunogenicity of meningococcal polysaccharide group A conjugate vaccine

Neisseria meningitidis is a leading cause of severe bacterial infections in infants and young children. As a major virulence factor, meningococcal capsular polysaccharide (PS) is poorly immunogenic and generally does not induce immunological memory. Conjugation of PS with a carrier protein can significantly increase the PS-specific immunogenicity and induce immunological memory. It is well known that the molecular shape/size of the conjugate vaccine is important for its immunogenicity. However, little is known about the molecular shape/size of the meningococcal conjugate vaccine. A meningococcal PS–ovalbumin (OVA) conjugate vaccine was prepared using cystamine as linker. Four components (P1–P4) with different molecular size were fractionated from the conjugate. Small angle X-ray scattering (SAXS) analysis revealed that the conjugate vaccine exhibited a rod-like shape similar to virus-like particles. PS-specific immunogenicity of the conjugate vaccine was related to its molecular shape and increased as a function of its molecular size. Thus, the present study provides a three-dimensional shape of the conjugate vaccine and helps to identify optimal design of a potent meningococcal conjugate vaccine.     

藻酸双酯钠对急性脑梗死患者血浆P-选择素的影响作用研究

目的探讨藻酸双酯钠(PSS)对急性脑梗死患者血小板活化作用的影响。方法急性脑梗死患者76例,随机分为两组:治疗组38例,每日静脉点滴PSS150mg;对照组38例,每日静脉点滴维脑路通600mg,均连续用药14d。于治疗前、治疗后第7天、第14天检测两组患者血浆P-选择素含量,并比较两组欧洲卒中量表(ESS)评分的差异。结果两组患者血浆P-选择素治疗前比较,差异无统计学意义(P>0.05);治疗后第7天、第14天时治疗组P-选择素明显低于对照组(P<0.01),且两组治疗第14天时均低于治疗前(P<0.05或<0.01)。结论PSS可通过降低血浆P-选择素水平而发挥抗凝、抗血小板活化作用,对急性脑梗死有较好的治疗作用。     

钝顶螺旋藻多糖和藻蓝蛋白对小鼠急性放射病的防护作用

本文报告了钝顶螺旋藻多糖（ＳＰＰ）和藻蓝蛋白（Ｃ－ＰＣ）对小鼠受致死剂量￣（６０）Ｃｏγ射线照射后３０天存活率的影响。在照射前５天每天给小鼠腹腔注射ＳＰＰ１２５ｍｇ／ｋｇ或Ｃ－ＰＣ５０ｍｇ／ｋｇ均能分别比对照组提高小鼠的存活率３３％和２８％同时观察了ＳＰＰ和Ｃ－ＰＣ对经￣（６０）Ｃｏγ射线亚致死剂量照射后小鼠血细胞生成的影响，结果显示，ＳＰＰ和Ｃ－ＰＣ可刺激照射后小鼠粒单系祖细胞和造血干细胞的形成，并增加骨髓有核细胞的数量。ＳＰＰ和Ｃ－ＰＣ还可以增加照射小鼠外周血细胞的总数。ＳＰＰ和Ｃ－ＰＣ对外周血红细胞数与血红蛋白量无显著的影响。结果提示：ＳＰＰ和Ｃ－ＰＣ可能促进￣（６０）Ｃｏγ射线照射小鼠造血功能的恢复。     

桃金娘果实中多糖的提取与含量测定

目的研究桃金娘果实中多糖的含量。方法采用紫外分光光度法测定桃金娘果实中多糖的含量,以葡萄糖为对照品,以苯酚-浓硫酸为显色剂,在波长487nm处测定样品溶液的吸光度。结果该方法线性关系良好(r2=0.99967),桃金娘多糖的含量为2.22%,RSD=4.13%(n=3);多糖回收率为99.30%,RSD=2.5%(n=3)。结论此方法操作简便,准确性好,灵敏度高。     

方格星虫多糖对5.0Gy ^60Coγ辐射损伤小鼠的保护作用

目的观察方格星虫多糖对亚致死剂量60Coγ射线照射小鼠的保护作用。方法将60只雄性C57BL/6J小鼠随机分为正常对照组、模型组、尼尔雌醇组及低（100 mg/kg·d）、中（200 mg/kg·d）、高（400 mg/kg·d）三个剂量方格星虫多糖组,每天一次灌胃给药,尼尔雌醇组照射前一天给予尼尔雌醇3.3 mg/kg灌胃,照射后0.5 h再次给予1.67 mg/kg尼尔雌醇灌胃。灌胃2 w后,除正常对照组外,各组均以剂量率为0.8 Gy/min的60Coγ射线全身照射一次,照射剂量为5.0 Gy。于辐照后3 d、14 d测定小鼠体重、外周血WBC,辐照后14 d测定小鼠胸腺指数,脾指数,骨髓细胞和脾细胞DNA含量,血清SOD和MDA含量。结果γ射线全身照射后第3天,方格星虫多糖低、中剂量组小鼠外周血WBC数明显升高（P〈0.05）。照后第14天,低剂量组小鼠外周血WBC数显著增高（P〈0.01）,中、高剂量组脾脏重量指数明显升高（P〈0.01和P〈0.05）,中剂量组脾脏DNA含量明显增高（P〈0.01）;低、中剂量组骨髓细胞DNA含量明显增高（P〈0.05）;低、中、高三个剂量组小鼠血清SOD活力明显增强,血清MDA含量明显下降（P〈0.05）。结论方格星虫多糖对亚致死剂量γ辐射损伤小鼠具有一定保护作用。     

枸杞多糖纯品与粗品免疫活性的比较

枸杞多糖粗品有明显的免疫促进作用已有报道。本研究将纯品枸杞多糖分为５个不同剂量的实验组,与枸杞多糖粗品进行比较。结果表明,枸杞多糖纯品低剂量（１０ｍｇ·ｋｇ－１·ｄ－１,５ｍｇ·ｋｇ－１·ｄ－１）显示出更明显的免疫增强效应。特别是１０ｍｇ·ｋｇ－１·ｄ－１剂量,各项免疫指标与粗品有显著性差异（Ｐ＜０．０１）。枸杞多糖有其最适剂量,并非剂量越大效果越好。枸杞多糖粗品与纯品的比较研究,为深层次开发利用枸杞资源和其临床使用价值提供了实验依据。     

Carrier priming or suppression: Understanding carrier priming enhancement of anti-polysaccharide antibody response to conjugate vaccines

Introduction

With the availability of newer conjugate vaccines, immunization schedules have become increasingly complex due to the potential for unpredictable immunologic interference such as ‘carrier priming’ and ‘carrier induced epitopic suppression’. Carrier priming refers to an augmented antibody response to a carbohydrate portion of a glycoconjugate vaccine in an individual previously primed with the carrier protein. This review aims to provide a critical evaluation of the available data on carrier priming (and suppression) and conceptualize ways by which this phenomenon can be utilized to strengthen vaccination schedules.

Methods

We conducted this literature review by searching well-known databases to date to identify relevant studies, then extracted and synthesized the data on carrier priming of widely used conjugate polysaccharide vaccines, such as, pneumococcal conjugate vaccine (PCV), meningococcal conjugate vaccine (MenCV) and Haemophilus influenzae type b conjugate vaccines (HibV).

Results

We found evidence of carrier priming with some conjugate vaccines, particularly HibV and PCV, in both animal and human models but controversy surrounds MenCV. This has implications for the immunogenicity of conjugate polysaccharide vaccines following the administration of tetanus-toxoid or diphtheria-toxoid containing vaccine (such as DTP).

Conclusion

Available evidence supports a promising role for carrier priming in terms of maximizing the immunogenicity of conjugate vaccines and enhancing immunization schedule by making it more efficient and cost effective.