Preparation of new tissue engineering bone-CPC/PLGA composite and its application in animal bone defects

To investigate the feasibility of implanting the biocomposite of calcium phosphate cement (CPC)/polylactic acid-polyglycolic acid (PLGA) into animals for bone defects repairing, the biocomposite of CPC/PLGA was prepared and its setting time, compressive strength, elastic modulus, pH values, phase composition of the samples, degradability and biocompatibility in vitro were tested. The above-mentioned composite implanted with bone marrow stromal cells was used to repair defects of the radius in rabbits. Osteogenesis was histomorphologically observed by using an electron-microscope. The results show that compared with the CPC, the physical and chemical properties of CPC/PLGA composite have some differences in which CPC/PLGA composite has better biological properties. The CPC/PLGA composite combined with seed cells is superior to the control in terms of the amount of new bones formed after CPC/PLGA composite is implanted into the rabbits, as well as the speed of repairing bone defects. The results suggest that the constructed CPC/PLGA composite basically meets the requirements of tissue engineering scaffold materials and that the CPC/PLGA composite implanted with bone marrow stromal cells may be a new artificial bone material for repairing bone defects because it can promote the growth of bone tissues.     

Preparation, Fundamental Characteristics and Biosafety Evalution of Compound rhBMP-2/CPC

1Introduction Calciumphosphatecement(CPC)isanewtypeof bonesubstituteinrecentyearswithagoodboneconduc tion,absorbability,biologicalcompatibilityandetc.The mechanicalfixationcangraduallyturnintobiologicalfixa tioninitsanaphase[1].Atthesametime,calciumphos phatecementhasbeenprovedtobeagoodcarrierofthe bonemorphogeneticprotein(BMP)[2],whichcanover cometheshortagesthatsimplexBMPwillbedilutedby enchymaanddecomposedbyproteaseafteritsimplanta tionintothehumanbody,anditseffectiveconcentration insom…     

Microstructure and mechanical properties of calcium phosphate cement/gelatine composite scaffold with oriented pore structure for bone tissue engineering

The macroporous calcium phosphate(CPC) cement with oriented pore structure was prepared by freeze casting. SEM observation showed that the macropores in the porous calcium phosphate cement were interconnected aligned along the ice growth direction. The porosity of the as-prepared porous CPC was measured to be 87.6% by Archimede’s principle. XRD patterns of specimens showed that poorly crystallized hydroxyapatite was the main phase present in the hydrated porous calcium phosphate cement. To improve the mechanical properties of the CPC scaffold, the 15% gelatine solution was infiltrated into the pores under vacuum and then the samples were freeze dried to form the CPC/gelatine composite scaffolds. After reinforced with gelatine, the compressive strength of CPC/gelatine composite increased to 5.12 MPa, around fifty times greater than that of the unreinforced macroporous CPC scaffold, which was only 0.1 MPa. And the toughness of the scaffold has been greatly improved via the gelatine reinforcement with a much greater fracture strain. SEM examination of the specimens indicated good bonding between the cement and gelatine. Participating the external load by the deformable gelatine, patching the defects of the CPC pores wall, and crack deflection were supposed to be the reinforcement mechanisms. In conclusion, the calcium phosphate cement/gelatine composite with oriented pore structure prepared in this work might be a potential scaffold for bone tissue engineering.     

针状硅灰石对磷酸盐骨水泥性能的影响

以磷酸氢二钾和磷酸二氢钾为固化液,以磷酸四钙、α-磷酸三钙、磷酸氢钙、焦磷酸钙、羟基磷灰石和碳酸钙为原料合成骨水泥,向其添加针状硅灰石,研究了针状硅灰石对其性能的影响。结果表明,在磷酸钙骨水泥中添加针状硅灰石可以缩短凝结时间,提高抗压强度。当针状硅灰石的添加量为3%,骨水泥性能达到最佳;其初凝时间、终凝时间分别为14和28 min,样品在Ringer’s模拟液溶液中浸泡2周后抗压强度达49.23 MPa,浸泡液的pH值变化幅度小(7.1~7.8),在安全范围之内。     

熟料粒度对骨粉/磷酸钙生物骨水泥结构与性能的影响

采用新方法首次将动物骨中的鱼骨引入到磷酸三钙和磷酸氢钙等原料体系中通过高温烧结制备磷酸钙基生物骨水泥（CPC）,以柠檬酸和柠檬酸钠的缓冲液为固化液、按一定的液固比制备固化试样,通过扫描电子显微分析（SEM）和力学性能测试等方法,研究了熟料粒度对其固化试样结构与抗压强度的影响.结果表明：制备过程中骨水泥粉末的粒度对其固化试样的微观结构及其抗压强度有着较为显著的影响,通过调整骨水泥粉末的粒度可达到优化其固化试样的微观结构和改善其力学性能的目的.     

Augmentation of pedicle screw fixation with calcium phosphate cement

To determine whether a biodegradable calcium phosphate cement (CPC) provides significant augmentation of pedide screw fixation or not, an in vitro biomechanical study was carried out to evalwate the biomechanical effea of CPC in the restoration and angmentation of pedide screw.fixation. Axial pullout and cyclic beruding resistance test were employed in the experiment, and polymethylmethacrylate (PMMA) was chosen as control. The results demonstrate that the pullout strengths following CPC restoration and augmentation are 74% greater on an average than those of the control group, but less than those of PMMA restoration group ard aygmentation group respectively ( increased by 126% versus control). In cyclic bending resistance test, the CPC augmented screws are found to withstand a greater number of cycles or greater loading with less displacement before loosening,but the augmentation effect of PMMA is greater than that of CPC.     

Effect of substitutional Sr ion on mechanical properties of calcium phosphate bone cement

A novel calcium phosphate cement was developed by adding different amount of SrO to tetracalcium phosphate during the fabrication process. The experimental results show that compressive strength of cements based on tetracalcium phosphate doped with SrO significantly increases with the increase of SrO content, approximately 60 MPa, whilst the mechanical behavior of CPC slightly decreases if 0.7wt% SrO is added. X-ray diffraction measurement confirms the setting reaction of doped cements is similar to that of pure calcium phosphate cement (CPC). Low crystalline hydroxyapatite (HA) is found to be the main constituent of set cement. A mechanical reinforcement effect is resulted from the substitution of Sr ion to Ca²⁺ in tetracalcium phosphate (TTCP), accelerating HA crystal formation and a more cross-linked cement structure. In vitro bioactivity tests showed that CPC added with 0.5wt% SrO had a more rapid degradation compared with pure CPC.     

论"三个代表"与党的现代化

"三个代表"重要思想是新世纪党的建设的伟大纲领,按照"三个代表"要求,以改革的精神推进党的建设,实际上就是推进党的现代化.党的现代化包括党的领导方式和执政方式、思想理论和制度、组织和作风等方面的现代化.党的现代化是党面临的重大而紧迫的任务.要以"三个代表"为理论指南和根本指针,努力推进党的现代化,使党始终走在时代前列,立于不败之地.     

Preparation of a Novel Calcium Phosphate Cement Using N-methylene Phosphonic Chitosan as a Gelling Agent

1Introduction Self hardeningcalciumphosphatecements(CPC)consistingoftetracalciumphosphate(TTCP)anddicalci umphosphate(DCPAorDCPD)havebeendeveloped since1986.ThereactionbetweenDCPAandTTCPis[1]:2CaHPO4 2Ca4(PO4)2OH2OCa10(PO4)6(OH)2.CPC isreadilyosseointegra…     

井冈山时期党员思想政治教育的特点及现实意义

井冈山时期党员思想政治教育的许多理论和实践,实际上已经是对如何保持党的先进性问题的最初思考。这一时期将树立崇高理想和坚定信念作为党员思想政治教育的首要目标,将克服各种非无产阶级思想作为党员思想政治教育的首要工作,将"党群关系"教育作为党员思想政治教育的重要内容。这些宝贵经验是中国共产党在新形势下搞好自身建设的思想宝库和理论泉源,对于进一步推进党的先进性建设,具有长期的指导作用和深远的现实意义。     

关于加强高校高知群体党建工作的调查分析

以高校高知群体的党建工作调查为研究对象，通过对414份调研数据的分析，提出了在构建社会主义和谐社会的过程中加强和改进党的建设，针对高校高知群体党建工作的现状，采取有效的措施，做好高知群体和各类人才中发展党员的工作，从而优化党员队伍的结构和分布，建设一支优秀人才高度密集的党员队伍，提高党组织的凝聚力和战斗力。     

三个代表思想提出的历史必然性

三个代表是中国共产党面向新世纪加强自身建设的理论学说和实践基础。学习和研究这一思想,对于我党的建设和今后的工作都有十分重要的意义。本试就三个代表思想提出的历史生作一初步阐释,认为三个代表不但是马克思主义执政党建设理论发展的必然结果,而且是对中国共产党历史的总结和对新时代的积极回应。     

控制系统设计中的满意优化原理

从矛盾指标问题的求解出发,提出了满意解的折衷优化原理。通过分析指标间的速度型矛盾度和速度型接近度来确定各指标的折衷权值,并将求得的折衷权值代入总体满意度函数进行满意优化设计。以二阶欠阻尼控制系统的设计为例,优化出系统的最佳阻尼比。     

论中国共产党执政理念价值实现原则

实现中国共产党执政理念的价值,必须坚持中国共产党执政核心理念与具体理念的统一;坚持中国共产党执政理念的实践性,坚持中国共产党执政理念价值实现的基本维度,从而构建以此为基本架构的执政理念价值实现原则.     

1921-1927年中国共产党对民族资产阶级的认识

中国共产党对民族资产阶级的认识经历了从笼统视之为革命对象,到提出与其合作,建立民主联合战线:从视之为民主革命的主体和领导力量,到提出无产阶级应当成为资产阶级民主革命的领导者;指明民族资产阶级是动摇不定的阶级,它既有革命性,又有妥协性;开始论证建立民族资产阶级民主共和国行不通.     

关于我国民法典制定的宏观思考

党的十五大提出了"依法治国,建设社会主义法治国家"的战略目标。在党的十六大上进一步明确了"依法治国"的战略思想。在刑法典修改工作完成后,民法典的起草工作已经在悄悄的准备起来。我们现在面临的任务就是:进一步完善我国民事法律制度,以适应发展社会主义市场经济的要求。     

黄埔一期中共学生述论

黄埔军校的创办是第一次国共合作的重要成果。中共派遣和推荐许多党团员和有志青年报考黄埔军校。一期学员先后加入中共的有110多人,他们是中共早期的年青骨干。他们担任着国民革命的先锋,在东征北伐战场上英勇奋战,做出突出贡献。国共合作破裂后,他们跟随中共继续革命斗争,在中共的军队建设的创建立业时期举足轻重。因主客观原因,他们的结局不尽相同。     

浅谈以创新精神推进“学习型党组织”的建设

党的十六大把建设学习型社会列入全面建设小康社会的战略目标。党的十七大又提出了以改革创新精神全面推进党的建设的命题。建设学习型党组织是新形势下党中央向各级党组织和全体党员干部推出的战略任务,其作用不容忽视,并在实践中不断探索学习型党组织建设的有效方法和途径,努力构建"学习型党组织"建设的长效机制。     

“一步法”制备PBT／粘土纳米复合材料

采用“一步法”成功制备了PBT／粘土纳米复合材料,即将PBT、天然蒙脱土、有机改性剂CPC三者同时熔融共混。XRD、TEM研究表明当MMT：CPC为3：1时,形成了粘土片层分布均匀的插层型纳米复合材料;与纯PBT相比,TGA和锥形量热仪结果显示其所形成的纳米复合材料具有更高的热稳定性和火灾安全性。     

院系党委(党总支)在二级管理中功能的范式重构

高校二级管理改革中发挥院系党委(党总支)的功能是保证办学方向、增强活力的重要举措,厘清院系党委(党总支)在学校二级管理中的作用范式现状和成因,准确分析范式重构的基本条件,提出行之有效的重构路径,为院系党委(党总支)在学校二级管理中的作用发挥提供理论依据。