Sethi V S, Burton S S, Jackson D V
Cancer Chemother Pharmacol. 1980;4(3):183-7. doi: 10.1007/BF00254016.
A rapid, sensitive and highly reproducible radioimmunoassay (RIA) has been devised for vincristine and vinblastine. These alkaloids bind to the antiserum very tightly with an association constant (Ka) of 5 x 10(9) M-1 as determined by Scatchard analysis. The kinetic association constant of the alkaloids, as determined by the 'on' and 'off' rates at 4 degrees C, is 30-fold higher than the Scatchard analysis value. At 4 degrees C, 80% of the alkaloid is bound to the antiserum within 20 min, and the remaining 20% reaches an equilibrium within 48-72 h. In the RIA procedure the amount of the alkaloid (1-2 ng) needed to compete for 50% binding remains unchanged when the reaction mixtures are incubated for 2, 4, or 20 h. By a modification of the RIA procedure, where the antiserum is first allowed to react with the unlabeled alkaloid followed by addition of the radiolabeled alkaloid, sensitivity of the assay has been increased five- to tenfold. Other drugs, such as adriamycin, CCNU, methyl CCNU, cyclophosphamide, 5-fluorouracil, heparin, hydrocortisone, prednisone, and nitrogen mustard do not interfere with the assay. This assay can thus be used to determine vincristine or vinblastine levels in 5 x 10(-10)--10(-9) M concentrations in biological fluids.
已设计出一种用于长春新碱和长春碱的快速、灵敏且高度可重复的放射免疫分析（RIA）方法。通过Scatchard分析确定，这些生物碱与抗血清紧密结合，结合常数（Ka）为5×10⁹ M⁻¹。通过4℃下的“结合”和“解离”速率测定，生物碱的动力学结合常数比Scatchard分析值高30倍。在4℃时，80%的生物碱在20分钟内与抗血清结合，其余20%在48 - 72小时内达到平衡。在RIA程序中，当反应混合物孵育2小时、4小时或20小时时，竞争50%结合所需的生物碱量（1 - 2 ng）保持不变。通过对RIA程序进行改进，即先让抗血清与未标记的生物碱反应，然后加入放射性标记的生物碱，该分析的灵敏度提高了五到十倍。其他药物，如阿霉素、洛莫司汀、甲基洛莫司汀、环磷酰胺、5 - 氟尿嘧啶、肝素、氢化可的松、泼尼松和氮芥不干扰该分析。因此，该分析可用于测定生物流体中浓度为5×10⁻¹⁰ - 10⁻⁹ M的长春新碱或长春碱水平。
