用于基因和药物传递的多肽及聚多肽材料

多肽和聚多肽作为一类新型的生物医用材料,由于其具有良好的生物活性、生物可降解性以及生物相容性而备受瞩目.将具有特殊生理功能的多肽作为基因或药物载体、或用于药物修饰等,可以提高基因转染效率,增强药物的靶向治疗效果,降低药物的毒副作用.本文综述了近年来多肽及聚多肽材料在这些生物医学领域的应用及进展,对部分活性肽的作用机制和...     

铋铅铜合金中铋的分离和测定

金属铋不仅是~(209)Bi(α,2n)~(211)At核反应制备砹-211的靶物质,而且也是~(206)Pb(d,2n)~(206)Bi核反应制备铋-206的一种稳定性同位素,它也是一种很好的半导体材料。砹-211放射出的α射线可以杀伤肿瘤细胞。H.A.Walder把铋-206的离子形式用于脑肿瘤定位     

功能多肽在肿瘤治疗中的应用及研究进展

多肽具有生物相容性好,功能多样化,生物体内响应性高及合成修饰方法简单易行等优点,已被广泛用于构建靶向药物传递系统。以具有靶向功能和刺激响应性的多肽为基础构建的药物传递系统,能够将药物定向地运送到肿瘤区域。药物传递系统到达肿瘤组织后,在肿瘤组织特殊微环境或外源刺激下,实现药物的精准释放。这种具有特异性肿瘤靶向和刺激响应型的多肽载体可以最大程度地提高药物的抗肿瘤效果,降低药物的毒副作用。本文简要介绍了常用的靶向多肽和刺激响应型多肽,并讨论了基于功能型多肽的药物载体在肿瘤治疗方面的应用。     

纳升电喷雾串联质谱分析修饰多肽及未知多肽的结构

随着生物技术的发展,许多合成多肽药物的N-端或C-端或两端进行了修饰,以提高药效、延缓半衰期或降低副反应,这给多肽药物的结构确证带来了难度.未知多肽来源于胃癌患者的胃液提取物.本文利用Q-TOF2正交加速电喷雾串联质谱分别测定了含修饰多肽和未知多肽的序列等,成功对修饰肽和未知肽的一级结构进行了确证.     

以gp41为靶标的小分子-多肽缀合物作为HIV-1融合抑制剂的设计、合成及活性初筛

芳基吡咯类小分子化合物NB-2衍生物(Noc或Npc)与衍生于C34中的靶标特异性多肽P26所形成的缀合物具有低纳摩尔水平的融合抑制活性.本文通过不同长度或不同柔性的连接臂将Noc或Npc与衍生于C34的靶标特异性多肽P27缀合,探讨了C34中a位残基I635和连接臂对缀合物活性的影响.人体免疫缺陷病毒1型(HIV-1)Env介导的细胞-细胞融合实验结果表明,多肽与小分子之间产生了强的协同作用.     

基于超高效液相色谱-高分辨质谱的多肽组学技术用于人参不同部位多肽的差异分析

采用基于超高效液相色谱-高分辨质谱的多肽组学技术对人参主根、支根、须根和芦头的多肽谱进行全面分析，旨在评价人参不同形态区域多肽表达的异同。本研究共表征62个数据库中已收录的人参多肽。结果表明，人参不同部位均富含多肽类成分。多肽组学研究发现，人参主根和支根、芦头与须根之间多肽含量具有显著差异，从鉴定到的多肽中共发现25个稳定表达的已知潜在多肽标志物。其中多肽种类及含量在主根与其他部位间差异最显著，为主根与非主根药效差异研究提供了新思路。本研究揭示了人参多肽结构多样性及人参不同部位人参多肽表达的异同，对人参化学特征评价具有重要意义，为人参质量控制和合理应用提供了化学依据。     

超滤法结合纳升液相色谱-串联质谱技术分析漏出性胸腔积液中多肽组分

漏出性胸腔积液中的多肽和蛋白质等生物分子直接或间接地与机体特定的生理、病理状态相关,反映了肺部或者全身其它部位疾病的信息.本研究利用超滤法将漏出性胸腔积液中的多肽组分进行分离,经脱盐富集后,进行纳升液相色谱-串联质谱分析.结果表明,在漏出性胸腔积液中共鉴定到来源于52种蛋白的314条多肽,超过一半的肽段来源于纤维蛋白原,并且许多肽段具有阶梯序列的特征.此外,在来源于胶原蛋白和纤维蛋白原的多肽中还发现了大量的脯氨酸氧化修饰.基因本体论富集分析显示,漏出性胸腔积液多肽组分所属蛋白均具有胞外分泌的属性.本研究给出了漏出性胸腔积液中多肽组的序列、等电点、分子量、翻译后修饰等理化参数的分布特征,为进一步寻找肺部疾病相关的多肽标志物提供了可借鉴的参考数据和分析方法.     

具有双活性序列的新型抗菌肽的设计及性质

设计合成了具有2个活性序列的线性和环状多肽及具有单个活性序列的短链多肽, 研究了它们的杀菌活性、 细胞毒性及溶血性. 结果表明, 线性肽和环状肽的杀菌活性高于短链肽. 利用计算模拟的方法计算了多肽与细菌细胞膜中一种重要的成分磷脂酰甘油(DMPG)的结合能. 结果表明, 多肽-DMPG的结合能与多肽的杀菌活性具有较高的相关性, 线性和环状多肽与DMPG的结合能大于短链肽. 线性和环状多肽均含有2个活性序列, 可提供多个荷正电氨基酸与荷负电的磷脂结合, 结合能较大, 杀菌活性较强. 采用模拟生物膜对其中几条多肽的作用机理进行了初步研究. 结果表明, 该类多肽有可能使正常哺乳动物细胞的细胞膜产生孔洞; 而对于细菌细胞膜, 多肽并未在膜上产生明显孔洞, 而是引起了细菌细胞膜的聚集.     

多肽分子自组装

源于自然界中广泛存在的蛋白质自组装现象,近年来多肽的自组装逐渐成为材料学和生物医学等领域的研究热点.通过合理调控多肽的分子结构以及改变外界的环境,多肽分子可以利用氢键、疏水性作用、π-π堆积作用等非共价键力自发或触发地自组装形成形态与结构特异的组装体.由于多肽自身具有良好的生物相容性和可控的降解性能,利用多肽自组装技术构建的各种功能性材料在药物控制释放、组织工程支架材料以及生物矿化等领域内有着巨大的应用前景.本文总结了近年来多肽自组装研究的进展,介绍了多肽自组装技术常见的几种结构模型,概括了多肽自组装的机理,并进一步阐述多肽自组装形成的组装体形态及其在材料学和生物医学等领域里的应用.     

螺旋型抗菌肽的疏水性对抗细菌与抗真菌活性的影响比较

α-螺旋型多肽HPRP-A1由15个氨基酸残基组成,来源于幽门螺杆菌核糖体蛋白L1的N端.本研究以HPRP-A1为模板,在其非极性面中心通过单个氨基酸定点取代的方法,形成一系列疏水性不同的多肽类似物,系统地研究疏水性对α-螺旋型多肽生物活性的影响.结果显示,多肽疏水性及所带净电荷对多肽生物活性起着重要的作用;HPRP-A1及疏水性相对较高的多肽类似物具有较好的广谱抗菌活性（包括革兰氏阳性菌、革兰氏阴性菌及真菌）,但也有相对较高的溶血活性;多肽的疏水性与所带净电荷的变化对多肽抗细菌活性与抗真菌活性所产生的影响有着相似的变化趋势和程度.这意味着多肽与细菌的作用机制和多肽与真菌的作用机制存在一定的相关性.多肽对细菌和真菌的抗菌活性存在特异性,为设计出具有临床应用前景的抗菌肽药物奠定了基础.     

Preparation and premilinary evaluation of astatine-211 labeled IgG via DTPA anhydride

A method for²¹¹At labeling of human IgG via DTPA anhydride is described. DTPA-IgD was prepared and²¹¹At was conjugated to human IgG by adding Na²¹¹At to the DTPA-IgG and reaction for 30 minutes at room temperature. The astatinated IgG was isolated by a Sephadex G₅₀ column and identified by size exclusion HPLC. The labeling procedure was executed in 1.5 hours and at least 60% of the added²¹¹At was found in the product. The in vitro and in vivo stability of²¹¹At-DTPA-IgG was evaluated.     

Recent progress of astatine-211 in endoradiotherapy: Great advances from fundamental properties to targeted radiopharmaceuticals

Astatine-211 (²¹¹At, t_1/2 = 7.21 h) emitting two α particles with energies of 5.87 and 7.45 MeV, can lead to a high linear energy transfer (LET = 98.84 keV/µm) and short tissue range (50～90 µm). Since the 1950s, ²¹¹At had stepped into endoradiotherapy and has always been regarded as one of the most promising α-emitters for targeted-alpha therapy (TAT) in various malignancies. In the past two decades, ²¹¹At related radiopharmaceuticals have achieved great progress in the studies of basic physicochemical properties of astatine, ²¹¹At labeling strategies, preclinical and clinical studies, producing profound effects in nuclear medicine. This work will give a panorama of ²¹¹At-related researches in the recent 20 years, which will cover both the fundamental insights of ²¹¹At radiochemistry and applied labeling compounds. It can provide some important hints for the studies of TAT and other radiopharmaceuticals applied in tumor radiotherapy.     

Corrosion study of heat exchanger tubes in pressurized water cooled nuclear reactors by conversion electron Mössbauer spectroscopy

A first attempt to label insulin, a small protein with significant affinity to tumors with the α-emitter ²¹¹At was performed by an indirect method using N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate (SPC) as a bi-functional linker, and the stability of the conjugated insulin (²¹¹At-insulin) was evaluated in vitro and in vivo. SPC was synthesized by using 5-bromonicotinic acid as the starting material. With this bi-functional linker, insulin was conjugated with ²¹¹At in a labeling yield of 30–40%, with radiochemical purity of more than 98%. After 24 hours at room temperature, the radiochemical purity was still more than 95%, implying that ²¹¹At-insulin is fairly stable in vitro. Biodistribution of ²¹¹At-insulin was investigated in NIH strain mice. ²¹¹At accumulated rapidly in the liver post injection, with the maximum uptake of 4.29%I.D/g at 30 minutes, and was mainly excreted by kidney. More importantly, ²¹¹At-insulin uptake in some key organs or tissues, especially in thyriod, stomach, lung and spleen, was much less than that of free astatide (²¹¹At^?). This result indicated that ²¹¹At-insulin has considerable stability in vivo as well as in vitro.     

Preparation and preliminary evaluation of <Superscript>211</Superscript>At-labeled amidobisphophonates

In this paper, 3-amino-1-hydroxypropylidene-1,1-bisphosphonate(APB), a amidobisphophonate was synthesized and labeled with the α-emitter ²¹¹At by an indirect method using N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate (SPC) as a bi-functional linker, and the conjugated amidobisphophonate (²¹¹At-SAPC-APB) was preliminarily evaluated in vitro and in vivo by comparison with free astatide (²¹¹At⁻) and ^99mTc-MDP. 3-amino-1-hydroxypropylidene-1,1-bisphosphonate(APB) was prepared using β-alanine as the starting material. With SPC bi-functional linker, APB was conjugated with ²¹¹At in a labeling yield of 80–90% with radiochemical purity of more than 99%. The conjugated amidobisphophonate (²¹¹At-SAPC-APB) exhibited considerable stability in vitro, in that the radiochemical purity of ²¹¹At-SAPC-APB was still more than 98% in 0.1 mol/L PBS (pH 7.6) or in fetal calf serum, even stayed for 24 h at room temperature (RT). Biodistribution of ²¹¹At-SAPC-APB was investigated in NIH strain mice by I.V injection. The results showed that ²¹¹At-SAPC-APB could rapidly locate in shank, with the maximum uptake of 23.70 ± 2.29% I.D/g at 6 h, earlier than that of ^99mTc-MDP at 12 h, and stayed in the bone for long time. Moreover, ²¹¹At-SAPC-APB uptake in some key organs or tissues, especially in thyriod, stomach, lung and spleen, was much less than that of free astatide (²¹¹At⁻), implying that ²¹¹At-SAPC-APB was constantly stable in vivo as well as in vitro. These results indicated that ²¹¹At-SAPC-APB will be a suitable candidate for the targeted radiotherapy of bone metastases and should be further investigated.     

Astatine-211 labeling of protein using TCP as a bi-functional linker: synthesis and preliminary evaluation in vivo and in vitro

With 2,3,5,6-tetrafluorophenyl 3-(nodo-carboranyl) propionate (TCP) as a new potential bi-functional linker, bovine serum albumin (BSA) was conjugated with ²¹¹At, and the conjugated model protein (²¹¹At-TCP-BSA) was preliminarily evaluated in vitro and in vivo by comparison with ²¹¹At-SAB-BSA and ²¹¹At-SAPC-BSA, which conjugated with ²¹¹At via aryl derivatives ATE (N-succinimidyl-3-(tri-n-butylstannyl) benzoate) or SPC (N-succinimidyl 5-(tributylstannyl)-3-pyridinecarboxylate). The radiolabeled intermediate ²¹¹At-TCP was coupled to BSA in yields ranging from 35 to 45% with radiochemical purity of more than 98%. The conjugated ²¹¹At-TCP-BSA exhibited considerable stability in vitro in 0.1 mol/L PBS (pH 7.6) at room temperature (RT), similar to ²¹¹At-SAPC-BSA and ²¹¹At-SAB-BSA. Biodistribution of the ²¹¹At conjugated protein was investigated in NIH strain mice by I.V injection. The results showed that ²¹¹At-TCP-BSA was constantly stable in vivo as well as in vitro, but more stable than ²¹¹At-SAPC-BSA and ²¹¹At-SAB-BSA. These results implied that radioastatinated carboranes based on B–At bonds are higher stability than radioastatinated aryl derivatives based on C–At to in vivo deastatination. In other word, TCP should be a promising bi-functional linker for ²¹¹At conjugation of proteins or antibodies.     

The preparation and cytotoxic properties of211at labelled concanavalin a bound to cell membranes

A method of labelling biologically active proteins with the alpha emmitting halogen²¹¹At is presented. The labelling procedure is discussed with reference to the chemistry of astatine. Proteins which have been labelled retain approximately 50% of their original biological activity. Using cell specific labelled proteins, dose response curves are given indicating that such reagents are extremely cytotoxic, D₃₇ human CML cells=5 atmos²¹¹At/cell. The research potential of²¹¹At labelled biologically active proteins is briefly discussed.     

211At labeling of a monoclonal antibody and its Fab fragment: Cytotoxicity on human gastric cancer cells and biodistribution in nude mice with tumor xenografts

An antigastric cancer monoclonal antibody, 3H11 and its Fab fragment, were labeled with #-emitter ²¹¹At using p-[²¹¹At] astatobenzoic acid (PAtBA) intermediate. The astatinated antibodies had conspicuous cytotoxic effect on human gastric cancer cell M85 in vitro. Tissue distribution of the astatinated antibodies were investigated in nude mice with subcutaneous tumor xenografts by i.v. injection. The astatinated Fab fragment was better suitable for 7.2-hour half life of ²¹¹At, since its tumor uptake remained higher (9.48–8.42 I.D%/g) than the astatinated intact antibody (~4.0 I.D%/g) from 3 to 14-hour post injection. However, the undesired high ²¹¹At uptake of the astatinated antibodies in some normal tissues, such as stomach, kidney and lung, suggested that the ²¹¹At labeled antibodies should be further explored.     

Wet harvesting of no-carrier-added 211At from an irradiated 209Bi target for radiopharmaceutical applications

Astatine-211 is one of the most promising -emitters for targeted cancer radiotherapy. However, research and clinical trials involving ²¹¹At-labeled radiopharmaceuticals have often been impeded due to the irregular and sometimes inconveniently low recovery yields obtained by the currently used dry distillation procedure. Therefore, a wet harvesting procedure isolating ²¹¹At from an irradiated ²⁰⁹Bi target was explored. The procedure involves target dissolution in concentrated HNO₃ and extraction of the high oxidation state ²¹¹At activity with butyl or isopropyl ether. This method resulted in consistent and nearly quantitative yields. The activity was re-extracted in aqueous phase and applied to NIS6 UVW human glioma cells transfected with cDNA encoding the human sodium/iodide symporter (NIS). The significant and specific uptake of ²¹¹At activity by these cells suggests that in the ether phase, high oxidation state ²¹¹At is reduced to [²¹¹At]astatide anion. The synthesis of the first astatinated organic compound derived from wet harvested ²¹¹At, 3-astatobenzoic acid (ABA), was achieved.This work was supported by Grants EB002980, CA42324 and CA91927 from the U.S. National Institutes of Health. Special thanks go to Michael Dailey and Shawn Murphy from the Duke University Medical Center PET Cyclotron Department for providing us with ²¹¹At activities and to Kevin Alston for the preparation of the bismuth targets. NIS cDNA was kindly gifted by Dr. Sissy M. Jhiang from Ohio State University, Columbus, Ohio.     

Wet harvesting of no-carrier-added 211At from an irradiated 209Bi target for radiopharmaceutical applications

Astatine-211 is one of the most promising -emitters for targeted cancer radiotherapy. However, research and clinical trials involving ²¹¹At-labeled radiopharmaceuticals have often been impeded due to the irregular and sometimes inconveniently low recovery yields obtained by the currently used dry distillation procedure. Therefore, a wet harvesting procedure isolating ²¹¹At from an irradiated ²⁰⁹Bi target was explored. The procedure involves target dissolution in concentrated HNO₃ and extraction of the high oxidation state ²¹¹At activity with butyl or isopropyl ether. This method resulted in consistent and nearly quantitative yields. The activity was re-extracted in aqueous phase and applied to NIS6 UVW human glioma cells transfected with cDNA encoding the human sodium/iodide symporter (NIS). The significant and specific uptake of ²¹¹At activity by these cells suggests that in the ether phase, high oxidation state ²¹¹At is reduced to [²¹¹At]astatide anion. The synthesis of the first astatinated organic compound derived from wet harvested ²¹¹At, 3-astatobenzoic acid (ABA), was achieved.This work was supported by Grants EB002980, CA42324 and CA91927 from the U.S. National Institutes of Health. Special thanks go to Michael Dailey and Shawn Murphy from the Duke University Medical Center PET Cyclotron Department for providing us with ²¹¹At activities and to Kevin Alston for the preparation of the bismuth targets. NIS cDNA was kindly gifted by Dr. Sissy M. Jhiang from Ohio State University, Columbus, Ohio.     

Studies on diffusion of hydrogen in PWR clad material

Journal of Radioanalytical and Nuclear Chemistry - We have measured excitation functions of 209Bi(7Li, 5n)211Rn, 209Bi(7Li, 6n)210Rn, and other reactions, with the aim of realizing a 211Rn/211At...