Patel P, Weitz J, Brooker L A, Paes B, Mitchell L, Andrew M
Department of Pediatrics, McMaster University, Hamilton, Ontario, Canada.
Pediatr Res. 1996 May;39(5):826-30. doi: 10.1203/00006450-199605000-00014.
We hypothesized that the immaturity of the newborn coagulation system may influence the procoagulant activity of clotbound thrombin. 125I-Labeled fibrin clots were prepared from adult and cord plasma, incubated in their respective plasmas, and fibrinopeptide A (FPA) production was measured. Cord plasma clots generated significantly less FPA compared with adult plasma clots (p < 0.001). Cord plasma clots incubated in adult plasma generated similar amounts of FPA as cord plasma clots in cord plasma. Adult plasma clots incubated in cord plasma clots generated more FPA than adult plasma clots in adult plasma. Adult and cord plasma clots were then incubated with purified human adult fibrinogen, and the discrepancy between adult and newborn plasma clots remained (p < 0.01). To compare the amount of clot bound thrombin, adult and cord plasma clots were sonicated and incubated with fibrinogen. Again, significantly less thrombin was seen in cord clots compared with adult clots (p < 0.01). Because cord plasma has lower prothrombin concentrations (0.5 U/mL) we increased cord plasma prothrombin concentration by the addition of purified prothrombin. Prothrombin supplemented cord plasma clots generated more thrombin than unsupplemented clots (p < 0.01) and in amounts similar to the adult system. In conclusion, decreased amounts of thrombin present in cord plasma clots compared with adult plasma clots results in less FPA production. The low plasma concentration of prothrombin in cord plasma is responsible for this phenomenon.
我们推测新生儿凝血系统的不成熟可能会影响与凝块结合的凝血酶的促凝活性。用成人血浆和脐带血血浆制备125I标记的纤维蛋白凝块，在各自的血浆中孵育，然后测量纤维蛋白肽A（FPA）的产生量。与成人血浆凝块相比，脐带血血浆凝块产生的FPA明显更少（p<0.001）。在成人血浆中孵育的脐带血血浆凝块产生的FPA量与在脐带血血浆中孵育的脐带血血浆凝块相似。在脐带血血浆凝块中孵育的成人血浆凝块比在成人血浆中孵育的成人血浆凝块产生更多的FPA。然后将成人和脐带血血浆凝块与纯化的成人纤维蛋白原一起孵育，成人和新生儿血浆凝块之间的差异仍然存在（p<0.01）。为了比较与凝块结合的凝血酶的量，将成人和脐带血血浆凝块进行超声处理并与纤维蛋白原一起孵育。同样，与成人凝块相比，脐带血凝块中可见的凝血酶明显更少（p<0.01）。由于脐带血血浆的凝血酶原浓度较低（0.5 U/mL），我们通过添加纯化的凝血酶原来提高脐带血血浆的凝血酶原浓度。补充凝血酶原的脐带血血浆凝块产生的凝血酶比未补充的凝块更多（p<0.01），且产生量与成人系统相似。总之，与成人血浆凝块相比，脐带血血浆凝块中存在的凝血酶量减少导致FPA产生减少。脐带血血浆中凝血酶原的低血浆浓度是造成这种现象的原因。
