QUICK A J
J Clin Pathol. 1960 Nov;13(6):457-62. doi: 10.1136/jcp.13.6.457.
Human oxalated plasma stored at 4 degrees C. until the prothrombin time is increased beyond 60 sec. is a reliable medium for assaying labile factor (factor V) because its response to added labile factor corresponds quantitatively to that of plasma from patients with congenital deficiency of this factor. Such an agreement is not obtained with plasma stored at 37 degrees C. The stability of labile factor is closely associated with ionized calcium. The addition of thrombin to fresh oxalated plasma causes an apparent hyperactivity of labile factor, but this is completely removed by adsorption with Ca(3)(PO)(2). Oxalated plasma when adsorbed with Ca(3)(PO(4))(2) before treatment with thrombin does not develop this adventitious activity, nor does it occur in stored plasma treated with thrombin. The seemingly high labile factor activity in serum can be explained by the activation of this factor which is independent of labile factor but acts synergistically with it. The true labile factor concentration can be determined only after the accelerator is removed by adsorption with Ca(3)(PO(4))(2). A close agreement between the consumption of prothrombin and the loss of labile factor during clotting is observed.
保存在4℃直至凝血酶原时间延长超过60秒的人草酸盐血浆，是测定不稳定因子（因子V）的可靠介质，因为其对添加的不稳定因子的反应在数量上与先天性该因子缺乏患者的血浆反应一致。保存在37℃的血浆则无法得到这样的一致性结果。不稳定因子的稳定性与离子钙密切相关。向新鲜草酸盐血浆中加入凝血酶会导致不稳定因子出现明显的活性增强，但通过用Ca₃(PO₄)₂吸附可将其完全消除。在用凝血酶处理之前先用Ca₃(PO₄)₂吸附的草酸盐血浆不会产生这种异常活性，在用凝血酶处理的储存血浆中也不会出现这种情况。血清中看似较高的不稳定因子活性可以通过该因子的激活来解释，这种激活独立于不稳定因子，但与之协同作用。只有在用Ca₃(PO₄)₂吸附去除促凝剂后才能确定真正的不稳定因子浓度。在凝血过程中观察到凝血酶原消耗与不稳定因子丧失之间有密切的一致性。
