聚醚醚酮及其复合材料修复桩核冠:问题与临床应用价值

背景:聚醚醚酮是具有良好机械性能、生物相容性、化学稳定性的特种塑料聚合物,可加入不同的填料形成新型复合材料,在桩核修复中有潜在的临床应用价值。目的:综述聚醚醚酮及其复合材料的性能、在桩核修复中的临床应用进展。方法:以“聚醚醚酮,桩核修复,金属桩,纤维桩,氧化锆桩”为中文检索词检索中国知网数据库,以“PEEK,polyetheretherketone post,post core repair,dental Dowels”为英文检索词检索PubMed数据库,检索时间范围重点为2019年1月至2023年10月。通过阅读文献题目、摘要及全文筛选,根据纳入与排除标准进行筛选,最后纳入71篇文献进行综述。结果与结论:聚醚醚酮是高性能热塑性聚合物,实验研究证明聚醚醚酮及其复合材料在机械性能、生物相容性、抗老化性、化学稳定性、粘接性能等方面具有优越性,在桩核修复领域应用前景喜人。聚醚醚酮及其复合材料作为桩核修复临床应用局限于前牙和前磨牙,但都获得了满意的修复效果。聚醚醚酮及其复合材料在桩核修复中属于新型材料,目前还有诸多问题尚待解决,如:3D打印设备和打印过程是否会影响材料的机械性能;临床修复效果观...     

3D生物打印技术及其在牙周骨缺损修复中的应用

与传统的"减材"制造相比,3D打印技术具有精确的个性化设计、快速成型、复杂精细产品制造等"増材"制造的明显优势。近年来,为了提高治疗的个性化及精确性,医学领域已经广泛应用3D生物打印技术进行术前诊断、手术设计、术前模拟以及组织再生等各个阶段。本综述首先介绍3D生物打印技术的概况及其过程,主要分为成像及模型设计、生物材料及细胞类型的选择、不同类型的生物打印等。在口腔牙周缺损修复中,3D生物打印技术通过重建其组织缺损部位的解剖结构,应用生物复合材料逐层精确地堆积出个性化植入物,增加了植入物的稳定性与术后骨结合率,使口腔组织形态及功能都得以恢复。然而,材料选择的局限性等问题给3D生物打印技术在修复牙周骨缺损的发展带来了障碍。本文就3D生物打印技术应用于牙周骨缺损修复中的复合生物材料、细胞、生物活性药物传递等几个方面逐一介绍。     

生物支架材料修复感染性骨缺损的研究进展

骨髓炎所致的感染性骨缺损复发频繁，难以治愈。各种生物支架材料作为极具潜力的新型骨植入材料，有效弥补了现今感染性骨缺损修复材料的缺陷。其中天然生物衍生材料具有良好生物相容性，人工合成无机材料和有机高分子材料抗感染能力显著，复合材料结合3D打印和表面涂层技术，改善了常规植入物机械性能差、抗菌能力差、缺乏骨诱导功能等缺点。生物支架材料已在修复感染性骨缺损、促进骨再生等方面展现出良好前景。本文就生物支架材料修复感染性骨缺损的研究进展作一综述。     

3D打印钛合金骨小梁多孔结构的拉伸性能

文题释义：3D打印：3D打印技术开创了增材制造的生产方式,即依照3D设计蓝图可将金属粉末等原材料逐层堆积而制成最终产品,擅长构建形状结构复杂的产品与个体化定制,制作特异性假体或植入物,供植入以达到重建等目的,在骨科领域得到了广泛应用。 钛合金骨小梁：是以钛合金粉末为原材料,采用金属3D打印技术通过金属微粒逐层熔融叠加生成的一种类人体骨小梁三维空间网孔结构,其力学性能和生物学性能和人体的松质骨骨小梁极为相似,作为人工植入假体的表面结构,具有非常出色的骨长入效果。 背景：3D打印钛合金多孔结构以其良好的机械性能和生物相容性已经在骨科植入假体设计与临床应用方面得到了快速发展,与涂层假体相比,钛合金骨小梁结构具有骨长入快和骨长入好的优点。为了保证骨科植入物的安全,目前多采用实验方式确定骨小梁结构的拉伸、剪切疲劳和弯曲疲劳强度。 目的：通过力学实验和有限元数值模拟方法研究骨小梁多孔结构的力学性能。 方法：①3D打印钛合金骨小梁拉伸试件实验：设计并制备3D打印钛合金骨小梁拉伸试件,骨小梁结构的丝径为0.28-0.35 mm、孔径为0.71 mm、孔隙率为73%。检测钛合金骨小梁结构的拉伸强度,分析其失效机制,同时分析不同打印位置对骨小梁拉伸强度的影响。②数值模拟实验：利用有限元方法建立包括骨小梁理论结构的拉伸试件实体模型,模拟骨小梁试件的拉伸破坏过程。 结果与结论：①3D打印钛合金骨小梁拉伸试件的极限载荷分布在39.55-47.11 kN之间,等效极限拉伸应力分布在62.79-74.53 MPa之间,拉伸破坏的结果为网状结构断裂,说明钛合金骨小梁具有较高的拉伸强度;②3D打印钛合金骨小梁拉伸试件实验与数值模拟实验均显示,骨小梁试件受到拉伸破坏时的破坏形式为丝径断裂,不会在骨小梁与钛合金实体的结合面发生断裂;③数值模拟实验中骨小梁试件的拉伸破坏载荷低于3D打印钛合金骨小梁拉伸试件,造成该差异的原因主要为：3D打印骨小梁试件的丝径(280-350 μm之间)大于骨小梁的理论丝径(142 μm),而孔径(孔隙率75%)小于骨小梁的理论孔径(孔隙率96%)。 ORCID: 0000-0001-7000-2093(张兰) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

聚醚醚酮及其复合材料作为骨科植入物的研究进展

文章总结了聚醚醚酮及其复合材料的生物活性和相容性的最新研究进展,同时综述了聚醚醚酮及其复合材料作为骨科植入物的应用现状,并分析其发展前景。     

磷酸钙材料在骨软骨缺损修复支架中的应用

背景：磷酸钙材料与天然骨矿物质相似,具有良好的生物活性、骨传导性和可降解性,在金属植入物涂层及骨缺损修复材料中已有大量研究与应用。 目的：综述不同物相磷酸钙材料的特点及在骨软骨支架中的应用。 方法：应用计算机检索PubMed数据库、中国学术期刊网络出版总库、维普数据库2000年1月至2015年2月的有关文章,中文检索词为“骨软骨,磷酸钙(包括羟基磷灰石、磷酸三钙、聚磷酸钙等),组织工程”,英文检索词为“osteochondral;calcium phosphate;tissue engineering”。 结果与结论：由于磷酸钙具有多种物相和晶型,通过不同工艺方法调控磷酸钙的结构尺寸可以得到丰富的材料体系,如羟基磷灰石、磷酸三钙、聚磷酸钙、无定形磷酸钙等,其生物学性能和力学性能均有所差异,其中以羟基磷灰石的应用最为广泛。将磷酸钙与其他材料复合制备多层的复合支架是骨软骨组织工程研究的一个趋势。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

生物降解材料复合成骨因子在骨科应用研究中的进展

背景：生物可降解植入物不仅可重建骨缺损部位,而且随着材料的逐步降解,新生骨组织可完全替代移植材料,填充骨缺损处。目的：总结生物降解材料复合成骨因子在骨科的研究进展。方法：以“可降解材料,成骨因子,细胞活性因子,骨组织工程;Biodegradable materials,factors,cell active factor,bone tissue engineering”为检索词,应用计算机检索PubMed、万方、CNKI数据库2000至2015年的相关文献。结果与结论：生物可降解医用高分子材料可分为天然高分子材料和人工合成可降解材料。天然高分子材料具有良好的生物相容性,但其机械强度较差;人工合成可降解材料械强度较天然高分子材料高,但容易造成局部酸性物质堆积,产生局部炎症反应。将生物可降解医用高分子材料与成骨因子复合,可提高材料的力学强度与骨诱导能力,但将其作为骨修复材料应用于临床还有很多问题需要解决。  中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

3D打印钛金属骨科植入物应用现状

3D打印技术近年来在骨科植入医疗器械领域发展迅速,由于其能够根据患者需求个性化地定制植入物形状,并且精确控制植入物的复杂微观结构,从而实现植入物外形和力学性能与人体自身骨的双重适配。生物医用钛及钛合金作为目前骨科植入物的主要原材料,具有优越的生物相容性,与3D打印技术结合,成为各国科学家以及医疗器械厂家研发的热点,促进3D打印钛金属骨科植入物的商业化。针对3D打印钛金属骨科植入物的特点、钛金属粉末要求、已上市产品情况、临床研究、存在的问题以及标准和审评规范等的现状与发展进行论述和展望。     

3D打印与组织工程心肌、心脏瓣膜、大血管及血管网的构建

背景：由于3D打印技术具有高度的仿生性和复制精微复杂结构的优势,被广泛应用于骨科、整形美容、医学修复与心血管疾病的诊疗中。 目的：综述3D打印技术在构建心脏瓣膜、再生血管、工程心肌组织和心血管疾病模型等方面的研究进展、优势及存在的问题,并展望其临床运用前景。 方法：由第一作者检索PubMed数据库、CNKI数据库2013年4月至2015年4月的相关文献,检索关键词为“3D printing,cardiovascular system,rapid prototyping;3D打印,心血管,快速成型技术”。 结果与结论：目前,3D打印技术涉及了心血管研究和应用的各个方面,在组织工程心肌、组织工程心脏瓣膜、组织工程大血管及血管网的构建上已有突破性进展,3D打印方案逐渐完善,其应用已从实验室研究走向临床应用。但在更广泛的运用前还有很多亟待攻克的难题,最为突出的问题之一是如何保证打印器官或组织的血供问题,尽管目前3D打印的管状结构已基本保证了组织器官的血供需求,但毛细血管的超微结构难以通过图像重建模仿,在构建局部微循环方面还有待进一步突破。 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

3D打印聚己内酯/纳米羟基磷灰石复合支架与骨髓间充质干细胞的体外生物相容性

文题释义： 3D打印技术：是通过计算机设计3D模型,按照某一坐标轴切成无限多个剖面,然后层层打印堆叠形成一个实体的立体模型,使用3D打印技术制备的骨组织工程支架能对支架的内部结构和外形进行自由可控的构建,在支架个性化、精确性、机械强度、孔隙调节、空间结构复杂性方面有独特优势。 纳米羟基磷灰石/聚己内酯复合材料：羟基磷灰石是人体和动物骨骼的主要无机成分,具有良好的骨诱导性,纳米羟基磷灰石由于良好的生物相容性和骨整合能力被广泛用作骨缺损的修复材料;聚己内酯是一种已被FDA批准的生物材料,具有良好的机械性能、生物相容性及降解性。两种材料复合物的多孔结构能够为细胞生长、组织再生及血管化提供有利条件。 背景：聚己内酯/纳米羟基磷灰石复合材料是在常用骨组织工程材料基础上结合3D打印技术制备的新型复合支架材料,目前对于该复合材料的体外生物相容性研究较少。 目的：通过体外实验探讨3D打印聚己内酯/纳米羟基磷灰石复合支架材料的细胞相容性。 方法：利用3D打印技术分别制备聚己内酯及聚己内酯/纳米羟基磷灰石复合支架,表征两组材料的微观结构、孔隙率及力学性能。将大鼠骨髓间充质干细胞分别接种于两组支架表面,CCK-8法检测细胞增殖率,扫描电镜和Live/Dead染色观察细胞在支架上的生长情况。 结果与结论：①两组支架均呈三维网状相互连通结构,纤维呈规律有序的排列、相互交错,纤维表面无空隙,纤维间距、直径较为均一;两组支架的孔隙率比较差异无显著性意义(P > 0.05);复合支架的弹性模量高于单纯聚己内酯支架(P < 0.05);②两组支架表面培养1 d的细胞增殖比较差异无显著性意义(P > 0.05),复合支架表面培养4,7 d的细胞增殖快于单纯聚己内酯支架(P < 0.05);③Live/Dead染色结果显示,两组材料均具有良好的细胞相容性,细胞活性较高,同时复合支架上的贴壁细胞更多一些;④扫描电镜显示,细胞在两种材料上生长形态良好,并紧密黏附于支架表面及微孔附近,同时可见分泌的细胞外基质呈丝状包绕于细胞周围;⑤结果表明,3D打印技术制备的聚己内酯/纳米羟基磷灰石复合支架孔隙较丰富,具备良好的力学性能,细胞相容性良好,可作为骨组织工程的支架材料。 ORCID: 0000-0002-7083-6458(胡超然) 中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程     

Cloning of photoreactivation repair gene and excision repair gene of the yeast Saccharomyces cerevisiae

Summary The photoreactivation repair gene (PHR1) of the yeast Saccharomyces cerevisiae was cloned in a hybrid plasmid (pJDB207), which is able to replicate as a multicopy episome in S. cerevisiae and Escherichia coli cells. The size of the DNA fragment found to have the photoreactivation activity was 3.0 kb, determined by recloning of the isolated fragment. In wild type cells transformed by the plasmid containing the PHR1 gene, the number of DNA photolyase molecules was 15 times greater than in wild type cells with pJDB207 only. Using the same receptor strain the excision repair gen RAD1 was also isolated. The size of the insert of the DNA which complements excision repair deficiency in recipient yeast cells was 5.7 kb. The recipient cells after transformation with the plasmid containing RAD1 showed the same UV-sensitivty as wild type cells with pJDB207 only.Abbreviation UV Ultra-violet light of 254 run wavelength     

Increased frequency of mutations in DNA from infertile men with meiotic arrest

In diverse organisms from yeast to mice, mutations in numerous genes required for DNA repair may lead to defects in meiosis. Although it is likely that meiosis is conserved throughout evolution, little is known about the genetics of meiosis in humans even though meiotic arrest associated with azoospermia is common. In this work, we compared the sequence fidelity of a polymorphic marker amplified from DNA of two groups of patients: those with testis biopsy suggesting meiotic arrest and those with normal spermatogenesis who were obstructed. We demonstrated that mutations are more common in DNA from testicular tissue derived from men with meiotic arrest than in DNA from testicular tissue derived from men with normal spermatogenesis and physical obstruction (P < 0.05). No mutations were observed in blood tissue from either group of men. This suggests the possibility that defects in genes required in DNA repair could contribute to meiotic arrest in men just as has been observed in other organisms.     

DNA错配修复蛋白多功能性的研究进展

DNA错配修复(mismatch repair,MMR)系统是DNA损伤修复的多种途径之一,存在于从细菌、酵母到人体的所有生物体,由一组高保守性酶蛋白组成.其通过校正DNA复制及重组中产生的碱基错配与插入/缺失环,维持所有生物基因组稳定性的功能已研究比较清楚.越来越多的研究还揭示了错配修复蛋白的其他功能:参与调控DNA损伤应答,同源重组,减数分裂的染色体配对和分离,抗体多样性产生及三核苷酸重复序列扩增等过程.本文将对错配修复蛋白多功能性的研究进展作一综述.     

Recombination between divergent sequences leads to cell death in a mismatch-repair-independent manner

Homologous recombination is an important DNA repair mechanism in vegetative cells. During the repair of double-strand breaks, genetic information is transferred between the interacting DNA sequences, thus creating a gene-conversion event. Gene conversion of a functional member of a gene family, which uses an inactive member (such as a pseudogene) as a template, might have deleterious consequences. It is therefore important for the cell to prevent recombination between divergent sequences. We have studied the repair of a double-strand break by recombination in a haploid yeast strain carrying 99% identical alleles located on different chromosomes. The fate of the broken chromosome was followed in the whole cell population without imposing selective constraints. Our results show that all the cells were able to repair the broken chromosome by gene conversion. During the repair, the cells arrest in the cell cycle with a “dumbbell” configuration characteristic of G2/M-arrested cells. Surprisingly, although all the cells repaired the broken chromosome, 60% of them were unable to resume growth and to form colonies after the repair was completed. The low level of cell recovery was due to the 1% divergence between the alleles, but was not dependent on the function of the mismatch-repair system. Cell death, however, could be prevented by the presence of an alternative source of perfect homology located on a different chromosome. Received: 11 January / 13 March 2000     

Differential effects of luminol,nickel, and arsenite on the rejoining of ultraviolet light and alkylation-induced DNA breaks

When Chinese hamster ovary cells were treated with ultraviolet (UV) light or methyl methanesulfonate (MMS), a large number of DNA strand breaks could be detected by alkaline elution. These strand breaks gradually disappeared if the treated cells were allowed to recover in a drug-free medium. The presence of nickel or arsenite during the recovery incubation retarded the disappearance of UV-induced strand breaks, whereas the disappearance of MMS-induced strand breaks was retarded by the presence of arsenite or of luminol, a new inhibitor for poly(ADP-ribose) synthetase. Luminol, however, had no apparent effect on the repair of UV-induced DNA strand breaks, and nickel had no effect on the repair of MMS-induced DNA strand breaks. When UV- or MMS-treated cells were incubated in cytosine arabinofuranoside (AraC) plus hydroxyurea (HU), a large amount of low molecular weight DNA was detected by alkaline sucrose sedimentation. The molecular weight of these DNAs increased if the cells were further incubated in a drug-free medium. This rejoining of breaks in cells pretreated with UV plus AraC and HU was inhibited by nickel and by arsenite, but not by luminol. The rejoining of breaks in cells pretreated with MMS plus AraC and HU was inhibited by luminol and by arsenite, but not by nickel. These results suggest that different enzymes may be used in DNA resynthesis and/or ligation during the repairing of UV- and MMS-induced DNA strand breaks, and that nickel, luminol, and arsenite may have differential inhibitory effects on these enzymes. © 1994 Wiley-Liss, Inc.     

Central Line Infections in Repaired Catheters: A Retrospective Review

BackgroundThere have been very few studies conducted to assess the infection risk of repairing a ruptured or broken tunneled central venous access device or a ruptured peripherally inserted central catheter (PICC), a procedure that is fairly common in a certain population of patients.MethodsIn a retrospective review of repairs to both tunneled central venous access devices and PICCs in a large metropolitan health system, 258 medical records were reviewed. During a 4-year period there were 258 repairs, 202 to PICC lines and 56 to tunneled catheters. The system-wide infection database was the source queried to provide evidence for and confirmation of a central line infection. This database is maintained by the infection control team using strict guidelines, reducing inter-rater reliability issues.ResultsThe Fisher exact test for proportions was used to compare infection rates between repaired infected and repaired noninfected lines. The infection rate was 5% in repaired catheters and 5.9% in unrepaired catheters (P = 1.00). On average, repaired catheters were in place longer (mean log [time-days in situ] 2.71 vs 2.31). Despite repairs and longer dwell times the repaired catheters did not have a significantly higher rate of infection when compared with unrepaired catheters.ConclusionsDespite longer dwell times the infection rate for repaired catheters was not statistically significant when compared with unrepaired catheters.     

DNA修复与顺铂耐药

顺铂的主要药理机制是损伤细胞DNA，肿瘤细胞DNA修复能力增强则会导致其对顺铂耐药。目前研究发现，DNA修复途径中的核苷酸切除修复、错配修复、碱基切除修复均与顺铂耐药有关，核苷酸切除修复为其中最为重要的途径。