van den Besselaar A M, Neuteboom J, Bertina R M
Department of Haematology, Leiden University Hospital, The Netherlands.
Blood Coagul Fibrinolysis. 1993 Dec;4(6):895-903.
The activated partial thromboplastin time (aPTT) is the most popular test for monitoring of heparin therapy. The purpose of the present study was to show that an aPTT reagent with good response to heparin can be prepared from synthetic phosphoglycerides. Mixed liposomes were prepared from synthetic dioleoylphosphatidylserine (DOPS), dioleoylphosphatidylcholine (DOPC), and dioleoylphosphatidylethanolamine (DOPE). These liposomes were used in an aPTT test system with kaolin as activator, to evaluate their procoagulant activity in the absence and presence of heparin. For comparison, mixtures of purified non-synthetic phospholipids were prepared and tested with the same systems. The aPTT and its response to heparin were influenced by the phospholipid class composition and concentration. The presence of phosphatidylserine (PS) was required to reduce the aPTT of normal plasma to values between 30 and 40s. The presence of phosphatidylethanolamine (PE) in mixed liposomes could modulate the response to heparin. At low PE/PS liposome concentrations (approximately 40 microM), a relatively low response was observed. At high liposome concentrations (approximately 1 mM), the response to heparin increased with the mole fraction of phosphatidylethanolamine. The results obtained with non-synthetic phospholipid mixtures were similar to those obtained with the synthetic phosphoglycerides. Optimal concentrations of DOPS, DOPE and DOPC were found with which an almost linear response to heparin and to low molecular weight heparin (Fragmin) was observed. Using a mixed liposome consisting of 12 microM DOPS/12 microM DOPC/16 microM DOPE, a doubling of the base-line aPTT was achieved at approximately 0.2 IU/ml of heparin, and at approximately 1.0 IU/ml of Fragmin.(ABSTRACT TRUNCATED AT 250 WORDS)
活化部分凝血活酶时间（aPTT）是监测肝素治疗最常用的检测方法。本研究的目的是表明，可以用合成磷酸甘油酯制备对肝素反应良好的aPTT试剂。由合成的二油酰磷脂酰丝氨酸（DOPS）、二油酰磷脂酰胆碱（DOPC）和二油酰磷脂酰乙醇胺（DOPE）制备混合脂质体。这些脂质体用于以高岭土为激活剂的aPTT检测系统，以评估它们在有无肝素情况下的促凝活性。为作比较，制备了纯化的非合成磷脂混合物并用相同系统进行检测。aPTT及其对肝素的反应受磷脂类别组成和浓度影响。需要磷脂酰丝氨酸（PS）的存在才能将正常血浆的aPTT降低至30至40秒之间的值。混合脂质体中磷脂酰乙醇胺（PE）的存在可调节对肝素的反应。在低PE/PS脂质体浓度（约40微摩尔）时，观察到相对较低的反应。在高脂质体浓度（约1毫摩尔）时，对肝素的反应随磷脂酰乙醇胺的摩尔分数增加。用非合成磷脂混合物获得的结果与用合成磷酸甘油酯获得的结果相似。发现了DOPS、DOPE和DOPC的最佳浓度，在这些浓度下观察到对肝素和低分子量肝素（速碧林）几乎呈线性反应。使用由12微摩尔DOPS/12微摩尔DOPC/16微摩尔DOPE组成的混合脂质体，在约0.2国际单位/毫升肝素和约1.0国际单位/毫升速碧林时，基线aPTT实现了翻倍。（摘要截短于250字）
