聚乙二醇修饰天花粉蛋白的初步研究

目的:研究聚乙二醇(PEG)修饰天花粉蛋白(TCS)的条件、纯化方法、生物活性及致过敏反应程度。方法:用SDS-PAGE检测反应条件对产物成分的影响,利用离子交换和分子筛凝胶层析对修饰产物进行分离纯化,通过SDS-PAGE和HPLC检测聚乙二醇化天花粉蛋白(PEG-TCS)的纯度,小鼠引产实验测定PEG-TCS体内生物学活性,用TCS和PEG-TCS作为抗原对豚鼠进行致敏和攻击。结果:在PEG修饰TCS的反应中,PEG与TCS的投料(质量)比和pH值是影响修饰效率的主要因素,修饰反应一般在24～48h内达到平衡;纯化的PEG-TCS经SDS-PAGE检测纯度大于95%,HPLC显示单一峰;小鼠引产实验表明,经过PEG修饰后的TCS,引产活性加强;豚鼠过敏反应实验表明,PEG-TCS具有极低的全身性过敏反应。结论:PEG修饰TCS的最佳反应条件为:TCS与PEG投料比为1:6,pH6．0,反应时间为48h,催化剂氰基硼氢化钠浓度为40mmol·L~(-1);PEG-TCS纯度大于95%; PEG-TCS体内活性能较好的保留,且全身性过敏反应降低。     

新型聚乙二醇化葡激酶的表达、纯化及功能鉴定研究

目的通过对葡激酶(SAK)基因序列进行定点突变、表达、纯化与进行聚乙二醇修饰以获得较高纯度的聚乙二醇化葡激酶(peg-SAK-cys),并对其溶栓活性与免疫原性初步进行验证。方法根据SAK蛋白晶体结构及抗原位点选择突变位点,设计引物将所选的氨基酸突变为半胱氨酸。将突变质粒通过化学转化进入BL21(DE3)感受态,并利用经典原核表达技术,在大肠杆菌中表达突变葡激酶(SAK-cys)。利用镍离子交换柱、分子筛等方法分离纯化目的蛋白。用纤维蛋白平板溶圈法和血栓弹力图初步对其生物活性进行验证。以酶联免疫吸附(ELISA)法评价peg-SAK-cys的免疫原性。结果成功获得了SAK-cys质粒,表达、纯化了突变蛋白,并进行聚乙二醇修饰获得了peg-SAK-cys,分离纯化后纯度在总蛋白质量的90%以上。计算其溶圈实验结果,活性为8.2×10~4IU·mg~(-1);血栓弹力图实验结果提示其具有较高的溶栓活性;免疫原性测定结果提示peg-SAK-cys免疫原性低于野生型SAK(P=0.000 2)。结论通过位点特异性特变与聚乙二醇修饰技术的联合运用可以成功改造出有较低免疫原性的活性SAK。     

半胱氨酸对人血管平滑肌细胞增殖和凋亡的影响

目的 观察半胱氨酸(Cys)对人血管平滑肌细胞(VSMCs)增殖和凋亡的影响.方法 采用组织贴块法体外培养人VSMCs,用不同浓度的Cys培养液孵育细胞24h,用MTT法检测VSMCs增殖,流式细胞术检测VSMCs凋亡.RT-PCR法检测bax mRNA的表达.结果 体外培养的人VSMCs在终浓度为100、200、500和10001μmol/L Cys的培养液中孵育24h后的吸光度(A)值均高于对照组(P<0.05),表明Cys可诱导人VSMCs增殖;但同时.VSMCs凋亡细胞数明显高于对照组(P<0.05),bax的表达增强,表明Cys亦诱导了人VSMCs凋亡.结论 浓度较高时半胱氨酸可同时诱导VSMCs增殖和凋亡.     

一种新型聚乙二醇化重组人生长激素的制备及性质考察

目的制备一种新型聚乙二醇化重组人生长激素(PEG-(rhGH)2),并对其理化性质及药理作用进行研究。方法以分子质量为2×104u的聚乙二醇二丙醛(PEG-(ALD)2)对重组人生长激素(rhGH)进行修饰,采用Sephacryl S-200凝胶过滤色谱、Q Sepharose FF离子交换色谱对修饰产物进行分离纯化,SDS-PAGE鉴定各组分,通过SEC-HPLC、IEF、MALDI-TOF-MS等方法对目标产物进行分析,并采用去脑垂体大鼠模型研究其体内生物活性与长效作用。结果获得了一种新型聚乙二醇化重组人生长激素(PEG-(rhGH)2)。其纯度质量分数达到97%以上,等电点为5.27,分子质量为6.6×104u。与未修饰的rhGH相比,PEG-(rhGH)2具有高效、长效的促进机体生长的药理作用。结论新型聚乙二醇化重组人生长激素PEG-(rhGH)2是一种具有开发前景的长效蛋白质药物,值得进一步深入研究。     

促胰岛素分泌肽的聚乙二醇化修饰和体内外生物活性研究

通过基于Byetta结构的促胰岛素分泌肽类似物的PEG修饰和筛选,以期获得一种长效促胰岛素分泌肽修饰物。利用化学合成的方法获得C末端突变成半胱氨酸的Byetta类似物(Ex4C),再用不同分子质量大小的马来酰亚胺活化的mPEG(MAL-mPEG)对其半胱氨酸的游离巯基进行定点修饰,修饰后产物用阴离子交换色谱和反相色谱进行纯化。通过测定其体外刺激RINm5F细胞释放cAMP的水平,以及体内对STZ模型小鼠的降血糖作用来评价其生物活性。MAL-mPEG化的促胰岛素分泌肽的SDS-PAGE及RP-HPLC纯度均达98%以上,且修饰位点专一;促胰岛素分泌肽经5 k、20 k、35 k分子质量大小的mPEG修饰后体外刺激RINm5F细胞释放cAMP的ED50分别为1.61 ng/mL、15.68 ng/mL、32.95 ng/mL;3种修饰物在相同剂量(40μg/kg)皮下给药对正常小鼠和STZ模型小鼠体内均有明显的降血糖作用,维持降血糖时间分别达24 h、48 h和72 h。     

聚乙二醇化蛋白质多肽类药物定点修饰策略

聚乙二醇修饰具有抵抗蛋白酶降解、提高稳定性、延长体内半衰期、降低免疫原性等优点,能够有效地改善蛋白质多肽类药物的临床药效。而聚乙二醇的定点修饰由于能够获得均一性和高活性保留率的产物,并能提高产物的产率,已经引起了广泛关注。本文概述近年来聚乙二醇定点修饰蛋白质多肽类药物方面的研究进展,并对聚乙二醇定点修饰技术的发展趋势进行了展望。     

抗肿瘤转移多聚β肽聚乙二醇化的研究

目的:研究抗肿瘤转移多聚β肽的聚乙二醇(PEG)化的方法及其作用。方法:采用甲氧基聚乙二醇丙醛(mPEGALD5000)修饰多聚β肽;采用电泳和成像分析系统检测修饰率。以粘附实验检测生物活性。结果:(1)二聚β肽(β2)的修饰率为66.7%,三聚β肽(β3)为52.7%。(2)最佳反应条件为:pH值为5,多聚β肽和mPEGALD5000的摩尔之比为1∶10,反应温度为4℃,反应时间为24h。(3)修饰后产物在4℃下可稳定放置50d。(4)修饰后产物水溶解度增加。(5)β2,β2-PEG,β3和β3-PEG对SMMC-7721和HCCLM6细胞与纤连蛋白(FN)粘附均具有显著的抑制作用(P<0.01),而且PEG修饰后作用显著增强(P<0.05或P<0.01)。结论:采用mPEGALD5000能有效地将多聚β肽PEG化。多聚β肽和PEG修饰物对肿瘤细胞与FN的粘附具有特异的抑制作用,且PEG修饰后作用增强。     

聚乙二醇修饰牛血红蛋白产物的分离纯化和检测

目的:研究聚乙二醇修饰剂单甲氧基聚乙二醇琥珀酰亚胺酯(SC-mPEG)对牛血红蛋白(BHB)修饰产物的合适的分离纯化、检测方法。方法:采用阳离子交换层析以及有机溶剂沉淀法进行分离,并采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)和三硝基苯磺酸(TNBS)法进行检测。结果:阳离子交换层析法分离出修饰与低修饰产物,TNBS法检测阳离子交换层析分离所得2个峰值产物的平均修饰率分别为52.95%和14.19%。结论:阳离子交换层析法可作为分离纯化SC-mPEG-BHB的方法;TNBS方法可作为检测SC-mPEG-BHB平均修饰率的方法。     

人甲状旁腺素(1-34)的合成与聚乙二醇化修饰

目的合成人甲状旁腺素(1 34) [hPTH(1-34) ]并进行聚乙二醇化修饰。方法应用固相多肽合成方法合成并经高效液相色谱纯化得hPTH(1-34) ,Cys-hPTH(1- 34)和hPTH(1-34)-Cys-NH2 。Cys hPTH(1-34)和hPTH(1-34)-Cys-NH2 在水溶液(pH 7～8)中分别与平均相对分子质量为5 0 0 0的单甲氧基马来酰亚胺基聚乙二醇(mPEG50 0 0 MAL)反应,经高效液相色谱纯化得Cys(mPEG50 0 0 MAL)- hPTH(1-34)和hPTH(1-34)-Cys(mPEG50 0 0- MAL) -NH2 。结果hPTH(1-34) ,Cys(mPEG50 0 0 MAL) hPTH(1 34)和hPTH(1 34) Cys(mPEG50 0 0 MAL) NH2 的质谱和氨基酸组成分析结果均与理论值一致。hPTH(1-34) -Cys(mPEG50 0 0-MAL) NH2 保持了较好的体外活性,Cys(mPEG50 0 0- MAL) hPTH(1-34)保持了较好的体内活性。结论采用一种简便的方法成功实现了对hPTH(1-34)的N端或C端的聚乙二醇化修饰     

聚乙二醇修饰牛胰核糖核酸酶

采用N-羟基珀酰亚胺活化酯法活化单甲氧基聚乙二醇,测定了聚乙二醇（PEG）的活化度为86.2%。以活化的PEG对牛胰核糖核酸酶进行化学修饰;分析了蛋白质被修饰程度。用毛细管电泳法给出了被修饰蛋白的修饰度与修饰蛋白分布的定量结果。比较了被修饰产物对大分子底物(酵母RNA)与小分子底物（2',3'-环磷酸胞嘧啶）的降解活力,其表观酶活力分别保留了52.8%和66.3%。结合毛细管电泳定量分析得到的修正酶活力略低于表观酶活力。     

Efficacy of gut lavage,hemodialysis, and hemoperfusion in the therapy of paraquat or diquat intoxication

Clinical and in vitro investigations were carried out to test the efficacy of gut lavage, hemodialysis, and hemoperfusion in the treatment of poisoning with paraquat or diquat. In a patient suffering from diquat intoxication 130 times more diquat was removed by gut lavage 30 h after ingestion than was removed by complete aspiration of the gastric contents.Determination of in vitro clearances for paraquat and diquat by hemodialysis showed that, at serum concentrations of 1–2 ppm, such as are frequently encountered in poisoning in man, toxicologically relevant quantities of herbicide cannot be removed from the body. At a concentration of 20 ppm, on the other hand, hemodialysis proved to be effective, the clearance being 70 ml/min at a blood flow rate of 100 ml/min. The efficacy of hemoperfusion with coated activated charcoal was on the whole better. Especially at concentrations around 1–2 ppm, the clearance values for hemoperfusion were some 5–7 times higher than those for hemodialysis.In a patient suffering from paraquat poisoning, both hemodialysis as well as hemoperfusion were carried out. The in vitro results could be confirmed: At serum concentrations of paraquat less than 1 ppm no clearance could be obtained by hemodialysis while by hemoperfusion with activated charcoal quite high clearance values were measured and the serum level dropped down to zero.

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Zusammenfassung Klinische Untersuchungen und Laboratoriumsversuche wurden durchgeführt, um die Wirksamkeit von Darmspülung, Hämodialyse und Hämoperfusion bei Paraquat- und Deiquat-Vergiftungen zu prüfen.Bei einem Patienten wurde 30 Std nach Deiquat-Aufnahme durch Darmspülung 130mal mehr Deiquat entfernt als durch vollständige Aspiration des Mageninhaltes. In vitro-Versuche ergaben, daß bei Blutserumkonzentrationen von 1–2 ppm, die bei Vergiftungen oft gemessen werden, durch Hämodialyse keine toxikologisch relevanten Paraquat- oder Deiquat-Mengen entfernt werden können. Dagegen erwies sich die Hämodialyse bei 20 ppm und einer Blutumlaufgeschwindigkeit von 100 ml/min mit einer Clearance von 70 ml/min als wirksam. Die Hämoperfusion mit beschicheter Aktivkohle war in diesen Versuchen aber eindeutig überlegen, denn insbesondere bei Konzentrationen um 1–2 ppm waren die Clearance-Werte 5–7mal höher als bei der Hämodialyse.Die in vitro-Ergebnisse wurden bei einem Patienten mit einer Paraquat-Vergiftung bestätigt: Bei Konzentrationen unter 1 ppm war die Hämodialyse wirkungslos, während durch Hämoperfusion relativ hohe Clearance-Werte erreicht wurden, so daß der Serumspiegel rasch unter die Nachweisgrenze abfiel.

     

In vitro studies on sterically stabilized liposomes (SL) as enzyme carriers in organophosphorus (OP) antagonism

This study describes a new approach for organophosphorous (OP) antidotal treatment by encapsulating an OP hydrolyzing enzyme, OPA anhydrolase (OPAA), within sterically stabilized liposomes. The recombinant OPAA enzyme was derived from Alteromonas strain JD6. It has broad substrate specificity to a wide range of OP compounds: DFP and the nerve agents, soman and sarin. Liposomes encapsulating OPAA (SL)* were made by mechanical dispersion method. Hydrolysis of DFP by (SL)* was measured by following an increase of fluoride ion concentration using a fluoride ion selective electrode. OPAA entrapped in the carrier liposomes rapidly hydrolyze DFP, with the rate of DFP hydrolysis directly proportional to the amount of (SL)* added to the solution. Liposomal carriers containing no enzyme did not hydrolyze DFP. The reaction was linear and the rate of hydrolysis was first order in the substrate. This enzyme carrier system serves as a biodegradable protective environment for the recombinant OP-metabolizing enzyme, OPAA, resulting in prolongation of enzymatic concentration in the body. These studies suggest that the protection of OP intoxication can be strikingly enhanced by adding OPAA encapsulated within (SL)* to pralidoxime and atropine.     

Aquatic Insects and Trace Metals: Bioavailability,Bioaccumulation, and Toxicity

Abstract

The uptake of metals from food and water sources by insects is thought to be additive. For a given metal, the proportions taken up from water and food will depend both on the bioavailable concentration of the metal associated with each source and the mechanism and rate by which the metal enters the insect. Attempts to correlate insect trace metal concentrations with the trophic level of insects should be made with a knowledge of the feeding relationships of the individual taxa concerned. Pathways for the uptake of essential metals, such as copper and zinc, exist at the cellular level, and other nonessential metals, such as cadmium, also appear to enter via these routes. Within cells, trace metals can be bound to proteins or stored in granules. The internal distribution of metals among body tissues is very heterogeneous, and distribution patterns tend to be both metal and taxon specific. Trace metals associated with insects can be both bound on the surface of their chitinous exoskeleton and incorporated into body tissues. The quantities of trace meals accumulated by an individual reflect the net balance between the rate of metal influx from both dissolved and particulate sources and the rate of metal efflux from the organism. The toxicity of metals has been demonstrated at all levels of biological organization: cell, tissue, individual, population, and community. Much of the literature pertaining to the toxic effects of metals on aquatic insects is based on laboratory observations and, as such, it is difficult to extrapolate the data to insects in nature. The few experimental studies in nature suggest that trace metal contaminants can affect both the distribution and the abundance of aquatic insects. Insects have a largely unexploited potential as biomonitors of metal contamination in nature. A better understanding of the physico-chemical and biological mechanisms mediating trace metal bioavailability and exchange will facilitate the development of general predictive models relating trace metal concentrations in insects to those in their environment. Such models will facilitate the use of insects as contaminant biomonitors.     

Steroidal sapogenin contents in some domestic plants

In order to find out the values of the steroid resources for the future use. the compositions and contents of steroidal sapogenins from 13 domestic plants have been investigated. As a result,Dioscorea nipponica, D. quinqueloba andSmilax china were found to have large amount of diosgenin. And pennogenin inTrillium kamtschaticum andParis verticillata, yuccagenin inAllium fistulosum, hecogenin inAgave americana and neochlorogenin inSolanum nigum were appeared to be major steroidal sapogenins.     

Alzheimer’s disease – current trends in basic and clinical research. Highlights from the 16th ECNP

Advances in the molecular biological knowledge of neuronal nicotinic acetylcholine receptors (nAChRs) have led to a growing interest by the pharmaceutical industry in the development of novel compounds that selectively modulate nAChR function. The ability of (-)-nicotine, an activator of nAChRs, to enhance attentional aspects of cognition in animals and humans, to exert neuroprotective and anxiolytic-like effects, and presumably to mediate the negative correlation between smoking and Alzheimer's (and Parkinson's) Disease, has focused interest on the potential therapeutic utility of modulators of nAChR function for treatment of some of the deficits associated with these progressive, neurodegenerative conditions. Numerous compounds are known which activate nAChRs and which might serve as lead compounds toward the development of such agents. The pharmacologic diversity of neuronal nAChR subtypes suggests the possibility of developing selective compounds which would have more favourable side-effect profiles than existing agents. This broader class of agents, collectively called cholinergic channel modulators (ChCMs), is anticipated to encompass compounds which would have more favourable side-effect profiles than existing agents, which generally exhibit low selectivity. This selectivity may be achieved by preferentially activating some subtypes of nAChRs (i.e., Cholinergic Channel Activators, ChCAs) or inhibiting the function of other subtypes (Cholinergic Channel Inhibitors, ChCIs). An overview of the biology of nAChRs and the rationale for the use of ChCMs for the treatment of dementia related to neurodegenerative diseases are presented, followed by a discussion of lead compounds and compounds under consideration for clinical evaluation.