Synergism between Tissue-Type Plasminogen Activator and a Genetically Engineered Variant Lacking the Finger Domain, the Growth Factor Domain and the First Kringle Domain
Synergism between Tissue-Type Plasminogen Activator and a Genetically Engineered Variant Lacking the Finger Domain, the Growth Factor Domain and the First Kringle Domain
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组织型纤溶酶原激活剂与缺乏指结构域、生长因子结构域和第一 Kringle 结构域的基因工程变体之间的协同作用
DOI：
10.1055/s-0038-1648136
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发表时间：
1991
影响因子：
6.7
通讯作者：
G. Pohl
中科院分区：
文献类型：
--
作者：
C. Mattson;K. Wikström;C. Sterky;G. Pohl
总结人组织型纤溶酶原激活剂（t-PA）的修饰变体缺乏指结构域（F）、生长因子结构域（G）和第一个Kringle结构域（K1），与t-PA相比，其体内血浆半衰期延长。当在体外测试变体（表示为K2 P）裂解人血浆凝块的能力时，我们发现活性的特征在于时滞期和S形剂量-反应曲线。然而，当K2 P与t-PA以4：1的w/w比混合时以及当允许K2 P裂解已经预先暴露于t-PA的凝块（即，进行有限的血浆消化）时，均观察到滞后期的体外衰减。根据单个剂量-反应曲线计算6小时内体外引起50%溶解的剂量，K2 P、t-PA和K2 P/t-PA（4：1 w/w）分别为540 ng/ml、360 ng/ml和310 ng/ml。这些结果表明K2 P和t-PA之间具有协同效应。然而，来自个体剂量-反应曲线的数据显示，K2 P/t-PA混合物的效果从未优于单独的t-PA的效果，因此认为体外协同效应的用途有限。在兔颈静脉血栓模型中评价了体内溶栓活性。尽管在体外观察到滞后期，但K2 P在体内（推注）的有效性约为t-PA的3倍。K_2P与少量t-PA（4：1 w/w）合用时，其溶栓作用进一步增强。与体外作用相反，体内的这种增强作用是一种有用的协同作用，因为K2 P/t-PA混合物的剂量-反应曲线比单独的t-PA和K2 P的剂量-反应曲线更陡。t-PA、K2 P和K2 P/t-PA在3小时内引起50%溶解的剂量分别为1.28 mg/kg、0.56 mg/kg和0.35 mg/kg。
Summary A modified variant of human tissue-type plasminogen activator (t-PA) lacking the finger domain (F), the growth factor domain (G) and the first kringle domain (K1), has an extended plasma half-life in vivo, compared to that of t-PA. When the variant (denoted K2P) was tested in vitro for its ability to lyse human plasma clots we found that the activity was characterized by a time lag phase and a sigmoidal dose-response curve. However, an attenuation of the lag phase in vitro was observed both when K2P was mixed with t-PA in a w/w ratio of 4 : 1 and when K2P was allowed to lyse a clot that had been pre-exposed to t-PA i.e. submitted to a limited plasmic digestion. Dosis that in vitro caused 50% lysis within 6 h were calculated from individual dose-response curves and were for K2P, t-PA and K2P/t-PA (4 : 1 w/w) 540 ng/ml, 360 ng/ml and 310 ng/ml, respectively. These results indicated a synergistic effect between K2P and t-PA. However, the data from individual dose-response curves showed that the effect of the K2P/t-PA mixture never was better than that of t-PA alone, and the synergistic effect in vitro is therefore considered to be of limited use. The thrombolytic activity in vivo was evaluated in a rabbit jugular vein thrombus model. Despite the lag phase observed in vitro, K2P was approximately 3 times as effective as t-PA in vivo (bolus injection). The thrombolytic effect of K2P was further potentiated when it was administred together with a small amount of t-PA (4 : 1 w/w). This potentiation in vivo was, in contrast to the effect in vitro, a useful synergistic effect as the dose-response curve for the K2P/t-PA mixture was steeper than that of t-PA and K2P alone. Doses that caused 50% lysis within 3 h were for t-PA, K2P and K2P/t-PA 1.28 mg/kg, 0.56 mg/kg and 0.35 mg/kg, respectively.