聚乙二醇(PEG-5000)对胰激肽释放酶化学修饰的初步研究

以自制单甲氧基聚乙二醇琥珀酰亚胺碳酸酯对猪胰激肽释放酶进行化学修饰，修饰产物以superdex 675凝胶色谱柱进行分离纯化。结果表明，修饰PPK分子质量增加，保留活性降低，对温度的耐受性加强，稳定性增加。     

单甲氧基聚乙二醇修饰L-门冬酰胺酶的研究

用一种单甲氧基聚乙二醇修饰剂修饰L-门冬酰胺酶，初步确定了最佳修饰条件，应用阴离子交换色谱和分子筛色谱分离纯化得到单修饰产物，酶活性回收率在40％以上，修饰产物的稳定性提高，免疫原性显著下降。     

单甲氧聚乙二醇化学修饰药物酶的研究进展

用单甲氧基聚乙二醉(1)化学修饰药物酶是生化药物研究开发的重要手段之一。本文综述了1化学修饰药物酶的一般方法及修饰后酶在生物和理化性质方面的变化，同时对1研究前景进行展望，并指出了尚待解决的问题。     

几种因素在L-天冬酰胺酶化学修饰中对酶活力及抗原性的影响

为了寻求在较好地保持酶活力的同时解除L-天冬酰胺酶抗原性的方法,采用不同分子量的乙酸酐、右旋糖酐和单甲氧基聚乙二醇,作为修饰剂和不同的修饰方法对该酶进行了化学修饰。结果表明在保持酶活性和降低抗原性方面,大分子修饰剂右旋糖酐、单甲氧基聚乙二醇优于小分子乙酸酐,底物保护修饰优于直接修饰;活化PEG,优于活化PEG₁。在底物保护下的PEG,修饰酶其抗原性完全解除的同时,酶活力保持在30%以上。     

比较两种消化酶对分离大鼠肝细胞的影响

目的:比较胶原酶和胰蛋白酶在分离大鼠肝细胞数量、活力、原代培养及MTT试验等四个方面的差别。方法:分别用胶原酶和胰酶分离获取大鼠肝细胞,通过台盼蓝拒染试验测细胞活力并计数,将分离的肝细胞进行原代培养并观察肝细胞形态变化,采用噻唑蓝(MTT)试验测肝细胞的增殖状况。结果:胶原酶分离的肝细胞数量是胰酶的2．4倍,而胰酶分离的肝细胞活力是胶原酶的2．8倍;胶原酶分离的肝细胞原代培养时贴壁慢,生长不良,而胰酶分离的肝细胞贴壁快,生长良好;MTT试验结果表明胰酶分离培养的细胞活性明显高于胶原酶。结论:胶原酶分离的细胞数量及纯度优于胰酶,而胰酶分离的细胞活力优于胶原酶。     

重组L-门冬酰胺酶的聚乙二醇化学修饰及修饰后酶的稳定性研究

目的单甲氧基聚乙二醇 (mPEG)化学修饰大肠杆菌重组L 门冬酰胺酶 (L ASP) ,考察经过修饰的酶的稳定性。方法N 羟基琥珀酰亚胺 (NHS)活化酯法活化mPEG ,生成的单甲氧基聚乙二醇琥珀酰琥珀酸亚胺酯 (SS mPEG)按不同摩尔比例与L ASP偶联 ,确定适合的反应时间和反应pH值。通过聚乙二醇化学修饰后的酶 (L ASP PEG) ,酶活力和纯度通过奈氏法和丙烯酰胺凝胶电泳 (SDS PAGE)检测 ,高效液相色谱检测L ASP PEG相对分子质量并考察了L ASP PEG体外稳定性等。结果SDS PAGE显示mPEG已经偶联到L ASP分子上 ,以两者摩尔比 1 0∶1为最佳 ,反应pH条件为 8.5 ,获得的L ASP PEG平均比活单位为 6 4 .8IU/mg ,相对分子质量为 30 1 80 0 ,体外稳定性高于L ASP。结论此实验确定了mPEG化学修饰L ASP最佳反应条件为 2 5℃反应 30min ,两者投料摩尔比为 1 0∶1 ,获得的L ASP PEG比L ASP稳定性高     

我院生化药物和酶诊断试剂的研制

概述近２０年我院在药用酶（胶原酶，链激酶，尿激酶，弹性酶，溶菌酶）、工业用酶（青霉素酰化酶，头孢菌素酰化酶，乙内酰脲酶）、诊断用酶（胆固醇，甘油三酯，肌酸激酶，乳酸脱氢酶，葡萄糖和尿素氮的测定）及透明质酸方面的研究开发     

两种方法联合应用设计新类型的胶原酶抑制剂

杜邦默克制药公司的研究者采用组合化学和基于结构的配体设计方法，设计了一种新类型的化合物，它们能够抑制引起癌转移和关节炎的胶原酶。这项工作有利于获得更有效的抑制癌细胞转移和治疗关节炎的新药物。研究人员发现新的抑制剂可以诱导它们所抑制的胶原蛋白酶在活性位点产生意想不到的构象变化。这种破坏性的胶原酶属于称为基质金属蛋白酶（ＭＭＰ）家族，在其活性位点含有Ｚｎ２＋。其中一种酶ｓｔｒｏｍｅｌｙｓｉｎ（ＭＭＰ－３）可以为跨越细胞外基质的癌细胞开辟道路，而另一种酶，人嗜中性胶原酶（ＭＭＰ－８）在软骨胶原的保护性…     

注射用胶原酶治疗腰椎间盘脱出症疗效及影像学分析

胶原酶是一种主要溶解胶原蛋白的酶。是从溶组织梭状芽胞杆菌中提取而成。此酶能溶解髓核和纤维环而不损害邻近组织。１９８１年、１９８４年美国Ｓｕｓａｍａｎ及Ｋｎｏｌ〔１〕分别报道了用胶原酶治疗腰椎间盘脱出症，疗效达８０％。国内１９８７年开始临床运用至今已有...     

抗菌素

Ⅳ-38 Kanamycin 的研究Ⅱ单甲氧基脱氧链霉胺结构的证明S.Umezawa、Y.Ito、S.FukotsuJ.(?)tibiot.(Japan)Ser. A.,1958 11,162摧毁甲基化的四-N 乙酰 Kanamycin 经酸水解后,得无色针形结晶:单甲氧基脱氧链霉胺,m.p.201—207(分解),[α]_0=0(2%水溶液)。它的盐酸盐在0.023N 过碘酸钠溶液中需消耗二克分子过碘酸盐,但     

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.     

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.     

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.