Analysis of Neonatal Hemostatic and Thrombotic Mechanism, and Exploring of the New Therapeutic Approach.

用血栓弹力图(TEG)研究新生儿的血液动力学机制。在新生儿早期，新生儿全血中TEG的r和k值缩短，TEG的mA值增大，而不是成人全血中的r和k值。在正常成人全血中加入活化的凝血酶、活化因子VIIa、ADP或肾上腺素，可重现新生儿TEG的高凝状态。其中一项数据，激活因子VIIa的结果，最近提交给了小册子中所附的《血栓与止血》杂志。另一篇关于高凝状态与抗血栓药物关系的论文也于近期发表。新生儿的出血时间和凝血时间基本正常，尽管与成人相比，新生儿的血小板功能和维生素K依赖的凝血因子浓度较低。但是，在病理状态下，新生儿血栓形成的发生率高于出生后儿童。新生儿的止血机制尚不清楚。根据我们最近的研究，在低出生体重到足月新生儿的脐带血中，von Willebrand因子(VWF)相对较高，von Willebrand因子裂解酶较低。此外，还检测到较高的vWF多聚体。这种较高的vWF多聚体止血作用更强。提示这可能与新生儿出血时间接近正常有关。我们还研究了脐带血中剪切依赖的血小板聚集。低切应力和高切应力的血小板聚集率较低，通过重建血液成分和测定胞外三磷酸腺苷活性来分析这一机制。脐带血的胞外ATPase高于成人血。提示ECTO-ATPase可能与抗血栓形成机制有关。

Neonatal hemoatatic mechanism was studied using thrombelastgram (TEG). In the early neonatal period, the r and k values of TEG in neonatal whole blood shortened and the ma value of TEG enlarged rather than these values in adult's whole blood. This characterized hypercoagulation prophile of TEG in neonate was able to be recreated by the addition of activated coagulation factors, such as thrombin, activated factor VIIa, ADP or epinephrine into normal adult whole blood. One of data, the results of activated factor VIIa, was recently submitted to the journal " Thrombosis and Haemostatic" enclosed in the booklet. And another paper concerning about the relationship between the hyper coagulation and anti-thrombotic drugs was recently subscribed. The bleeding time and coagulation time were almost normal in neonate despite the low function of platelets and the low concentrations of vitamin K dependent coagulation factors in neonate compared with adults. But, in pathological state, the thrombosis is more frequent in neonate than in children after neonate. The knowledge of the haemostatic mechanism is still obscure in neonate. From our recent study, von Willebrand factor (vWF) was relatively high and von Willebrand factor-cleaving protease was low in cord bloods of low birth weight to full term neonate. Furthermore, the higher multimer of vWF was detected. This higher multimer of vWF is more potent in hemostasis. And it may be suggested that it is related to be near normal bleeding time in neonate. We have also studied on the shear dependent platelet aggregation in cord bloods. And the low and high shear stress platelet aggregation were low, this mechanism were analyzed by the recreated blood components and the measurement of ecto-ATP activity. Ecto-ATPase in cord bloods was higher than that in adult blood. It may be suggested that ecto-ATP ase is related to the anti-thrombotic mechanism.