颗粒状β-磷酸三钙复合骨形态发生蛋白2修复齿槽裂骨缺损

背景：齿槽裂的修复已成为唇腭裂序列治疗中的一个重要环节。以人工骨为载体进行优化组合制成具有高度骨诱导活性的复合人工骨,极大地提高了临床上骨缺损修复的治疗效果。 目的：观察β-磷酸三钙复合骨形态发生蛋白2修复齿槽裂的效果。 方法：选择连云港市第二人民医院口腔科收治的齿槽裂患者24例,随机分为实验组和对照组,实验组应用骨形态发生蛋白2/β-磷酸三钙复合物修复齿槽裂,对照组应用自体髂骨松质骨修复。 结果与结论：两组切口均一期愈合,无植入物排出。随访时间3~12个月,修复后3个月X射线可见局部骨性愈合,修复后1年实验组人工骨部分被自体骨取代,骨吸收不明显,而对照组骨吸收明显。Enemar等分级标准评估实验组Ⅰ级疗效率为84%,对照组Ⅰ级疗效率为17%,两组相比差异有显著性意义(P < 0.05)。提示颗粒状β-磷酸三钙复合骨形态发生蛋白2修复齿槽裂,具有恢复形态准确,修复创伤小的优点;植入物组织相容性好,具有骨引导性,可降解,能被自体骨完全取代,且无不良反应,是一种良好的齿槽裂修复方法。     

生物活性离子改性透钙磷石骨水泥的生物和理化性能

背景:透钙磷石骨水泥作为一种骨替代和骨填充材料,因其具有良好的生物相容性、骨传导性等优点,尤其是相比于其他磷酸钙类骨水泥具有更好的生物降解能力,在骨修复方面有重要应用价值,但也因其存在机械性能不足、固化反应快及注射性能差等问题的限制,目前一般只能用于非负重区骨的修复。目的:探讨生物活性离子(金属离子和非金属离子)改性透钙磷石骨水泥,以期拓展使用范围。方法:利用Pub Med、Science Direct和中国知网、万方数据库检索2018-2023年发表的文献,中文检索词为“金属离子,铁,铜,锶,镁,锌,非金属离子,改性,骨,透钙磷石骨水泥”;英文检索词为“metal ion,iron,Fe,copper,Cu,strontium,Sr,magnesium,Mg,zinc,Zn,non-metal ion,modification,bone,Brushite Cements”。通过阅读标题、摘要对所得文献进行初筛,排除重复及内容不相关文献,最终纳入64篇文献进行综述。结果与结论:(1)生物活性离子影响透钙磷石骨水泥水化反应过程,不同离子以离子取代的方式掺入透钙磷石骨水泥晶体结构中,改变了骨水泥晶体形态,引起凝固时间、注射性、抗压强度等理化性能改变。(2)离子改性的透钙磷石骨水泥因不同的晶体结构而产生不同的离子释放效应,不同类型离子具有如促血管生成/成骨、抗菌及抗肿瘤等特性而发挥作用,此外,透钙磷石骨水泥具有良好的生物降解性,这对于各离子性能的发挥具有极大优势。(3)不同离子改性透钙磷石骨水泥理化性能影响如下:铁、铜、锶、镁、锌、银、钴可延长凝固时间;锶、镁可提高注射性能;铜、锶、镁、银、硅可增强抗压强度;能同时改善透钙磷石骨水泥以上3种理化性能的离子有锶、镁;良好的理化性能是临床应用的前提,故离子改善透钙磷石骨水泥的凝固时间、注射性及抗压强度等性能对骨水泥的研究应用具有重要意义。(4)不同离子改性透钙磷石骨水泥生物性能影响如下:铜、锶、镁、锌、钴、锂、硅、硒具有促血管生成/成骨效应;铁、铜、镁、锌、银具有抗菌特性;镁离子具有抗炎特性;铜、硒具有抗肿瘤性。(5)综上所述,镁离子能改善透钙磷石骨水泥凝固时间、注射性和抗压强度,同时具有促新生血管生成/成骨及抗菌性,对合并感染的骨缺损治疗具有良好应用前景;此外,铜还具有抗肿瘤特性,因此铜离子在感染、肿瘤引起的骨缺损治疗方面有巨大潜力;只是目前相关研究仍处于基础研究阶段,不同离子掺杂浓度和合成条件等对透钙磷石骨水泥理化性能的影响需进一步探索,同时对于生物性能影响也需更长期的研究观察。     

重组人骨形态发生蛋白2/骨修复材料的制备与性能

BACKGROUND: It has become a hotspot to prepare the bone repair material that exhibits natural bone structure and is used in combination with biological factors. OBJECTIVE: To prepare the recombinant human bone morphogenetic protein-2 (rhBMP-2)/bone repair material, and to evaluate its capacities of release, activity and ectopic osteoinduction. METHODS: A collagen-binding domain was added to the N-terminal of native rhBMP-2 that allowed bind to collagens in the bone repair material. Then, rhBMP-2/bone repair material was obtained through freeze-dried method. The releasing ability of rhBMP-2 in vitro was assayed by ELISA. C2C12 cell lines were loaded to the composite material with 0.25, 0.5 and 1 µg rhBMP-2, respectively. Afterwards, alkaline phosphatase activity was detected at 72 hours. The composite materials with 0, 2, 5 and 10 µg rhBMP-2 were implanted into the quadriceps of Sprague-Dawley rats, respectively. Alkaline phosphatase activity and the newly formed bone were detected at 2 and 4 weeks after implantation. The CY-7-labeled composite material was implanted into the quadriceps of Sprague-Dawley rats to observe its stability. RESULTS AND CONCLUSION: Substantially no rhBMP-2 from the rhBMP-2/bone repair material was released within 45 days. The alkaline phosphatase activity of C2C12 was in a rise with the increased concentration of rhBMP-2. The stability of the composite material in vivo was better, the alkaline phosphatase activity and ectopic bone formation increased as the concentration of rhBMP-2 rose. To conclude, the rhBMP-2/bone repair material preserves the stability of rhBMP-2, and improves ectopic osteoinduction ability.     

磷酸钙骨水泥复合骨形态发生蛋白6和血管内皮生长因子修复骨缺损

背景：单独将骨形态发生蛋白或血管内皮生长因子植入体内易被血液冲刷掉而不能最大限度发挥诱导成骨和血管生成作用,同时缺少载体的支撑作用。 目的：观察骨形态发生蛋白6、血管内皮生长因子及磷酸钙骨水泥联合应用在骨缺损修复过程中的作用。 方法：制作新西兰兔双侧股骨内侧髁骨缺损模型,左侧分别植入磷酸钙骨水泥/骨形态发生蛋白6/血管内皮生长因子、磷酸钙骨水泥/骨形态发生蛋白6及磷酸钙骨水泥,右侧不植入任何物质作为空白对照。植入8,16周通过硬组织切片组织学观察、电镜扫描等手段观察新骨形成情况。 结果与结论：各组材料的组织相容性良好,未见明显炎症组织反应。植入8周时,磷酸钙骨水泥/骨形态发生蛋白6/血管内皮生长因子组骨水泥-骨组织交界处基本上被新生骨小梁包绕,材料进一步降解,新生骨小梁表面可见大量活跃的成骨细胞;16周时,新生骨小梁继续长入,进一步增长、增粗、增多,有大量新生编织骨成网格状长入材料中,骨水泥材料降解明显,与周围组织结合紧密,降解与骨长入同步,此组不同时间点成骨速度及成骨效果均明显优于其他两组材料(P < 0.05)。表明3种材料联合应用可协同促进骨缺损修复。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;组织工程全文链接：     

缓释型重组人骨形态发生蛋白2/壳聚糖生物骨修复材料诱导骨形成

背景：重组人骨形态发生蛋白2在体内半衰期短、易降解代谢,达不到理想的骨再生效果。 目的：制备缓释型重组人骨形态发生蛋白2/壳聚糖生物骨修复材料,并观察其缓释性能、骨诱导活性。 方法：将重组人骨形态发生蛋白2与壳聚糖混合制备壳聚糖膜,涂覆于生物骨修复材料表面,ELISA方法检测其体外释药性能。茜素红染色检测缓释型人骨形态发生蛋白2/壳聚糖生物骨材料、重组人骨形态发生蛋白2生物骨材料、单纯骨填充材料诱导C2C12细胞骨钙蛋白的形成,观察其诱导成骨细胞能力。同时将3种骨修复材料植入清洁级KM小鼠股部肌袋内,2周后检测新生骨Ca2+离子含量,评价其异位骨诱导能力。 结果与结论：材料表面的壳聚糖膜分布均匀,负载的重组人骨形态发生蛋白2呈团簇状。重组人骨形态发生蛋白2/壳聚糖生物骨修复材料体外释药存在突释,前4 d释放量达总药量的50%,持续至12 d,释药量达到90%,第18天时释放完全。与单纯骨填充材料、重组人骨形态发生蛋白2生物骨材料相比,缓释型人骨形态发生蛋白2/壳聚糖生物骨修复材料诱导C2C12细胞向成骨晚期分化能力与异位骨形成能力显著增强(P < 0.05)。结果提示缓释型人骨形态发生蛋白2/壳聚糖生物骨修复材料缓释性能好,促进骨形成能力强。     

缓释重组人骨形态发生蛋白2仿生纳米纤维肝素/明胶复合支架的制备及表征

BACKGROUND: Bionic structure is one of the most important goals of scaffold design in tissue engineering. However, the majority of the bionic scaffolds do not have the capacity of sustained release of growth factors.     

重组人骨形态发生蛋白2诱导骨修复的应用及前景

背景：重组人骨形态发生蛋白2具备诱导成骨时间更早、成骨量较天然骨形态发生蛋白2多、生物学活性好、生物相容性好、成本低等特点,已成为近年来临床骨科创伤疾病防治研究的热点。 目的：总结重组人骨形态发生蛋白2在骨组织工程及骨修复领域应用中的优势、不足及目前国内外的研究进展。 方法：经第一作者检索CNKI数据库及SPRINGERLINK数据库2005至2011年与重组人骨形态发生蛋白2在诱导骨再生、骨组织修复有关研究进展方面的文献,英文检索词为“rhBMP-2,bone tissue engineering,bone repair materials”,中文检索词为“重组人骨形态发生蛋白2,骨组织工程,骨修复”。共检索出98篇,最终保留30篇进行归纳总结。 结果与结论：骨骼内天然骨形态发生蛋白2含量稀少、提取成本高昂,临床应用严重受限。重组人骨形态发生蛋白2有显著的成骨诱导能力,在骨组织工程及骨修复领域展现了巨大的潜在应用价值。体外试验无细胞毒性具有良好的生物相容性可供临床应用,其中重组人骨形态发生蛋白2和重组人骨形态发生蛋白7现已被应用于外科整形手术诱导骨再生,但由于重组人骨形态发生蛋白2是外源性细胞生长因子,临床应用多为超生理剂量,故潜在有软组织水肿,皮肤红疹、局部炎症反应、异位骨化和免疫反应等不良后果的危险,所以重组人骨形态发生蛋白2用于人体后的安全性研究还须长期密切关注。找到理想的载体,有效控制其在体内缓释是重组人骨形态发生蛋白2应用研究的关键问题。     

聚乳酸-乙醇酸共聚物-磷酸三钙-骨形态发生蛋白2人工骨结合肌肉移植修复骨缺损

背景：大段骨缺损修复多以植骨为主,如果能将带血运的组织与人工骨同时植入,理论上更有利于新生组织血运建立及人工骨的爬行替代重建。 目的：观察聚乳酸-乙醇酸共聚物-磷酸三钙-骨形态发生蛋白2人工骨结合自体带血供自体肌肉移植修复大段骨缺损的效果。 方法：手术造成30 mm绵羊大段桡骨缺损,抽签随机分为3组：实验组植入聚乳酸-乙醇酸共聚物-磷酸三钙-骨形态发生蛋白2人工骨及自体带血运的屈指长肌,对照组仅植入聚乳酸-乙醇酸共聚物-磷酸三钙-骨形态发生蛋白2人工骨,空白对照组未植入任何材料。3组均以钢板固定骨缺损区,术后24周进行X射线检测及组织学观察。 结果与结论：实验组桡骨缺损处完全成骨修复,皮质骨与髓腔轮廓清晰,骨痂为较成熟板层骨;对照组骨缺损基本完全修复,但新生骨密度及髓腔轮廓清晰度及骨痂成熟度均不如实验组;空白对照组无有效骨痂形成,缺损区被大量纤维组织填充。说明聚乳酸-乙醇酸共聚物-磷酸三钙-骨形态发生蛋白2人工骨结合自体带血供肌肉移植能够很好修复绵羊桡骨30 mm的大段骨缺损。     

Cem-OsteticTM人工骨浆复合骨形态发生蛋白对山羊椎体骨缺损修复作用研究*

目的 观察人工骨浆复合骨形态发生蛋白（BMP）对成年山羊椎体骨缺损的修复作用,并探讨其临床应用的可行性。方法将健康成年山羊24只随即分成单纯Cem-Ostefic^TM人工骨浆组（A组）和Cem-OsteticrM／BMP人工骨浆复合骨形态发生蛋白组（B组）,每组12只动物。在山羊胸腰段3处不相邻椎体分别建立椎体压缩性骨折撑开复位后骨缺损模型。将Cem-Ostetic^TM/BMP人工骨浆复合材料填充于缺损处,同时设立单纯人工骨浆对照组。术后4周、8周、12周分别处死动物,每组每次处死4只。通过大体观察,影像学检查,HE染色和生物力学测试。结果术后4周及8周时B组成骨情况、材料降解速度及生物力学强度和刚度测试明显优于A组（P〈0．05）,但仍未达到正常椎体的力学性能,差异有显著性（P〈0．01）。第12周时,两组X线及CT下均可见大量新骨生成,基本完整填充空隙,填充材料均基本完全降解,生物力学测试两组强度和刚度无显著性差异,基本达到了正常椎体的力学性能。结论Cem-Ostetic^TM人工骨浆是BMP的良好载体,Cem—Ostetic^TM／BMP复合材料具有较强的传导成骨和诱导成骨活性,生成的新骨有良好的强度和刚度。     

重组人骨形态发生蛋白2复合骨在腰椎融合中的效果

背景：诸多研究已证实重组人骨形态发生蛋白2在骨形成及骨折愈合中发挥十分重要的作用,但单纯予以重组人骨形态发生蛋白2植入容易出现扩散和降解,无法对新骨形成予以持续性的影响。 目的：观察重组人骨形态发生蛋白2复合骨在兔腰椎中的融合效果。 方法：取30只新西兰大白兔,构建后路腰椎横突间植骨融合模型,随机均分为3组,分别在L5-6横突间植入自体髂骨、同种异体骨及重组人骨形态发生蛋白2复合骨(重组人骨形态发生蛋白2与同种异体骨复合物),植入后6周,进行大体观察、X射线检查及组织学观察。 结果与结论：重组人骨形态发生蛋白2复合骨组融合率、新生骨组织在总面积中所占百分比高于自体髂骨组、同种异体骨组(P < 0.05);重组人骨形态发生蛋白2复合骨组、自体髂骨组拉伸强度大于同种异体骨组(P < 0.05),前两组拉伸强度无差异。X射线显示3组植骨区均可见骨痂形成;组织学显示,自体髂骨组移植物已消失,形成大量软骨,有少量骨小梁,并有一定编织骨形成;同种异体骨组有较多的纤维组织包裹材料,有骨岛形成,有数量较少的骨小梁及软骨形成;重组人骨形态发生蛋白2复合骨组存在大量骨小梁和少量软骨,形成编织骨且有皮质骨形成。表明重组人骨形态发生蛋白2复合骨在兔腰椎中可以获得良好的融合效果。 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     

Comparison of bone regeneration in a rabbit skull defect by recombinant human BMP-2 incorporated in biodegradable hydrogel and in solution

The objective of this study is to compare bone regeneration induced by recombinant human bone morphogenetic protein-2 (rhBMP-2) incorporated into a biodegradable gelatin hydrogel with that by rhBMP-2 in aqueous solution. After treating rabbit skull defects of 6 mm diameter with the two rhBMP-2 dosage forms, both of them increased the bone mineral density (BMD) at the skull defects with implantation time to a significantly higher extent than a rhBMP-2-free aqueous solution and a rhBMP-2-free empty gelatin hydrogel (p < 0.05). There was no quantifiable difference in BMD between the two dosage forms of rhBMP-2. Histological examination revealed that the integrity of newly generated bone increased with the rhBMP-2 dose, irrespective of the dosage form. The bone defect was filled with regenerated bone 21 days after treatment.     

骨形态发生蛋白-7基因变异与新疆维吾尔族人糖尿病和胰岛素抵抗的相关性

目的 探讨骨形态发生蛋白-7(bone morphogenetic protein 7,BMP7)基因变异与新疆维吾尔族人糖尿病、胰岛素抵抗的关系.方法 采用以流行病学调查为基础的病例-对照研究,选取717名(男276人、女441人)维吾尔族人作为研究对象,根据是否患有糖尿病分成糖尿病组(502例,男191例、女311例)和正常对照组(215人,男85人、女130人).首先在48例维吾尔族糖尿病患者中测序筛查 BMP7基因功能区的变异位点,选取代表性变异位点应用TaqMan-PCR技术在研究人群中进行基因型鉴定并开展病例-对照关联研究.结果 在 BMP7基因的功能区共发现5个新的和8个已知的变异位点.BMP7基因的2个代表性变异位点rs6025422、rs17480735均符合Hardy-Weinberg平衡.男性人群中rs6025422变异的AA、AG、GG基因型在糖尿病组及正常对照组中的频率分布差异有统计学意义(P<0.05),但对P值校正后差异无统计学意义(P>0.05),而总人群及女性人群中rs6025422变异基因型频率分布在病例、对照组间差异无统计学意义(P>0.05).男性人群中rs6025422变异不同基因型组间空腹血糖、空腹胰岛素水平、HOMA指数存在差异,并且AA、AG、GG 3组呈现递减趋势(P<0.05),而在总人群及女性人群中未发现上述现象.Logistic分析提示男性人群中rs6025422变异GG基因型是糖尿病的保护性因素(OR=0.637,95%可信区间0.439～0.923,P<0.05).结论 BMP7基因变异位点rs6025422可能与新疆维吾尔族男性糖尿病、胰岛素抵抗相关.

Abstract：

Objective To investigate the association between the genetic variations of the functional region in bone morphogenetic protein gene (BMP7) with type 2 diabetes mellitus in Chinese Uygur individuals. Methods A case-control study was conducted based on epidemiological investigation. A total of 717 Uygur subjects (276 males and 441 females) were selected and divided into two groups: diabetes mellitus group (n=502, 191 males and 311 females) and control group (n=215, 85 males and 130 females). All exons, flanking introns and the promoter regions of BMP7 gene were sequenced in 48 Uygur diabetics. Representative variations were selected according to the minor allele frequency (MAF) and linkage disequilibrium and genotyped using the TaqMan polymerase chain reaction method in 717 Uygur individuals, a relatively isolated general population in a relatively homogeneous environment and a case-control study was conducted to test the association between the genetic variations of BMP7 gene and type 2 diabetes mellitus. Results Five novel and 8 known variations in the BMP7 gene were identified. All genotype distributions were tested for deviations from Hardy-Weinberg equilibrium (P>0.05). There was significant difference of genotype distribution of rs6025422 between type 2 diabetes mellitus and control groups in the male population (P<0.05, P adjusted >0.05), but there was no difference in total and female population (P>0.05). And the means of fasting blood glucose (FBG), fasting insulin and HOMA-index significantly decreased in individuals with AA, AG and GG genotypes of rs6025422 in male population (P<0.05), but not in total and female population (P>0.05). The logistic regression analysis showed that GG genotype of rs6025422 variation might be a protective factor for diabetes in male (OR=0.637,95% confidence interval 0.439-0.923,P<0.05). Conclusion The present study suggests that the rs6025422 polymorphism in BMP7 gene may be associated with diabetes mellitus and insulin resistance in Uygur men.     

Low‐level laser therapy (780 nm) combined with collagen sponge scaffold promotes repair of rat cranial critical‐size defects and increases TGF‐β, FGF‐2, OPG/RANK and osteocalcin expression

The aim of this study was to evaluate the effect of collagen sponge scaffold (CSS) implantation associated with low‐level laser therapy (LLLT) on repairing bone defects. A single 5‐mm cranial defect was surgically created in forty Wistar rats, which then received one of the following four interventions (n = 10 per group): no treatment (G0); bone defect implanted with collagen sponge scaffold (CSS) alone (G1); defect treated with low‐level laser therapy (LLLT) (wavelength 780 nm; total energy density 120 J/cm²; power 50 mW) alone (G2); and CSS associated with LLLT treatment (G3). After surgery, animals in each group were euthanized at 21 days and 30 days (n = 5 per euthanasia time group). Bone formation was monitored by X‐ray imaging analysis. Biopsies were collected and processed for histological analysis and immunohistochemical evaluation of transforming growth factor‐beta (TGF‐β), fibroblast growth factor‐2 (FGF‐2), osteoprotegerin (OPG) and receptor activator of nuclear factor ? (RANK). Osteocalcin (OCN) was detected by immunofluorescence analysis. Compared to the G0 group, defects in the 30‐day G3 group exhibited increased bone formation, both by increase in radiopaque areas (P < 0.01) and by histomorphometric analysis (P < 0.001). The histopathological analysis showed a decreased number of inflammatory cells (P < 0.001). The combined CCS + LLLT (G3) treatment also resulted in the most intense immunostaining for OPG, RANK, FGF‐2 and TGF‐β, and the most intense and diffuse OCN immunofluorescent labelling at 30 days postsurgery (G3 vs. G0 group, P < 0.05). Therefore, the use of CCS associated with LLLT could offer a synergistic advantage in improving the healing of bone fractures.     

成纤维细胞生长因子23和骨形态发生蛋白7介导维生素D受体表达下降在2型糖尿病并发骨质疏松大鼠发病中的作用

目的 探讨2型糖尿病并发骨质疏松大鼠肾和骨组织维生素D受体(VDR)、成纤维细胞生长因子(FGF)23、骨形态发生蛋白(BMP)7的表达及意义.方法 雌性Wistar大鼠随机分为假手术对照组(NS组)、单纯去卵巢组(NOVX组)、2型糖尿病假手术组(DS组)、2型糖尿病去卵巢组(D0VX 组).糖尿病组大鼠予高脂高糖饲料联合小剂量链脲佐菌素腹腔注射制备2型糖尿病模型,模型成功后去卵巢组行双侧卵巢切除术,去卵巢后4周、8周、12周末随机分批处死.用RT-PCR法观察各组肾和骨组织VDR、FGF23、BMP7的mRNA表达,Western免疫印迹法观察各组肾组织VDR、FGF23、BMP7蛋白表达.结果 成功制备2型糖尿病并发骨质疏松模型.随着时间延长,DS组和DOVX组肾和骨组织VDR、BMP7的mRNA表达和肾组织VDR、BMP7蛋白表达均较NS组和NOVX组降低,且以DOVX组表达最低(P＜0.05);DS组和DOVX组骨组织FGF23的mRNA表达明显低于NS和NOVX组(0.566±0.059,0.452±0.057比1.008±0.068,0.520±0.049,P＜0.05),而DS组和DOVX组肾组织FGF23的mRNA和蛋白(1.034±0.071,1.136±0.112比0.919±0.086,0.952±0.143)表达明显高于NS和NOVX组,以DOVX组表达最高(P＜0.05).结论 FGF23和BMP7在肾和骨组织共同介导2型糖尿病并发骨质疏松大鼠维生素D受体表达中起不同作用.     

A cyclin-binding motif in human papillomavirus type 18 (HPV18) E1^E4 is necessary for association with CDK-cyclin complexes and G2/M cell cycle arrest of keratinocytes, but is not required for differentiation-dependent viral genome amplification or L1 capsid protein expression

The G2/M arrest function of human papillomavirus (HPV) E4 proteins is hypothesized to be necessary for viral genome amplification. Full-length HPV18 E1^E4 protein is essential for efficient viral genome amplification. Here we identify key determinants within a CDK-bipartite consensus recognition motif in HPV18 E1^E4 that are critical for association with active CDK-cyclin complexes and in vitro phosphorylation at the predicted CDK phosphorylation site (threonine 23). The optimal cyclin-binding sequence (⁴³RRLL⁴⁶) within this E4 motif is required for G2/M arrest of primary keratinocytes and correlates with cytoplasmic retention of cyclin B1, but not cyclin A. Disruption of this motif in the E4 ORF of HPV18 genomes, and the subsequent generation of stable cell lines in primary keratinocytes revealed that this motif was not essential for viral genome amplification or L1 capsid protein induction. We conclude that the HPV18 E4 G2/M arrest function does not play a role in early vegetative events.     

Regulatory proteins for the activated third and fourth components of complement (C3b and C4b) in mice. I. Isolation and characterization of factor H: the serum cofactor for the C3b/C4b inactivator (factor I)

Factor H, purified from mouse EDTA-plasma using a 4-step procedure, consists of a single polypeptide chain of Mr 150,000 on SDS-PAGE. Mouse H (Hmo) was required for the cleavage of fluid-phase mouse C3b by mouse I (Imo). The final product of degradation of fluid-phase mouse C3b was iC3b, consisting of fragments of the alpha'-chain (alpha'-70, alpha'-43) linked by disulfide bonds to an intact beta-chain. Imo alone was capable of cleavage of membrane-bound mouse C3b and of generating iC3b. The addition of Hmo nevertheless had an enhancing effect on Imo activity, but cleavage did not proceed beyond iC3b. These observations suggest that one important function of Hmo is to permit the inactivation of fluid-phase C3b, and to inhibit irreversibly its activity. The concentration of H in the plasma of male and female BALB/c mice was not significantly different. Among different inbred strains of mice, large differences were observed in the plasma levels of H, and plasma H levels were positively correlated with the plasma levels of C3. This observation, taken together with the well known role of H in the control of the activation of the alternative pathway, suggests that the turnover of C3 is controlled to some extent by H.