FAWCETT D M, OLDE G L, McLEOD L E
Can Med Assoc J. 1962 May 26;86(21):965-70.
Between 41 and 94% of the radioactivity of 24 preparations of I(131) supplied without cysteine preservative was non-iodide on chromatographic analysis. Extraneous radio-activity was essentially absent from I(131) supplied with cysteine. It was converted to iodide-I(131) by 10(-3) M cysteine or iodide but not by incubation at pH 2. The average thyroid uptake of I(131) containing extraneous radioactivity was significantly lower than the uptake of I(131) free from non-iodide impurity in 16 human subjects measured under controlled conditions and in a random group of 669 patients. Incubation of samples of I(131) containing non-iodide radioactivity with tyrosine and cupric chloride resulted in the non-enzymatic formation of monoiodotyrosine-I(131) either in the presence or absence of thyroid homogenate. Enzymatic formation of monoiodotyrosine-I(131) by thyroid homogenates could be demonstrated only when I(131) free from extraneous activity was used.
在不添加半胱氨酸防腐剂供应的24份I（131）制剂中，41%至94%的放射性在色谱分析中为非碘化物。添加半胱氨酸供应的I（131）基本不存在外来放射性。它可被10⁻³M半胱氨酸或碘化物转化为碘化物-I（131），但在pH 2条件下孵育则不能。在16名在受控条件下测量的人类受试者以及669名随机分组的患者中，含有外来放射性的I（131）的平均甲状腺摄取量显著低于不含非碘化物杂质的I（131）的摄取量。将含有非碘化物放射性的I（131）样品与酪氨酸和氯化铜一起孵育，无论有无甲状腺匀浆，都会非酶促形成单碘酪氨酸-I（131）。只有当使用无外来活性的I（131）时，才能证明甲状腺匀浆可酶促形成单碘酪氨酸-I（131）。
