（3H）和（125I）示踪剂在类固醇放射免疫分析中的应用。
Use of (3H) and (125I) tracers in steroid radioimmunoassays.
作者信息
Jeffcoate S L
出版信息
Pathol Biol (Paris). 1975 Dec;23(10):903-5.
UNLABELLED
The comparative use of 3H and 125I tracers in steroid radioimmunoassays will be discussed around the following points: 1. 3H. a)
ADVANTAGES
they can be purchased commercially and have a long shelf-life. b) Disadvantages: they may have reduced affinity for antibodies due to "isotope effects"; the counting of beta-emitters is more expensive and difficult; 3H tracers are not available for all steroids. 2. 125I. a)
ADVANTAGES
gamma-counting is cheaper, simpler and more precise; 125I tracers may have higher affinity for antibodies than unlabelled steroids; 125I can be used to label any steroid. b) Disadvantages: 125I tracers have a limited shelf-life (n.b. six months for 125I histamine tracers). The high affinity of some tracers will be a big disadvantage if the unlabelled steroid cannot compete effectively.
未标记
将围绕以下几点讨论在类固醇放射免疫分析中3H和125I示踪剂的比较使用：1. 3H。a) 优点：可商业购买且保质期长。b) 缺点：由于“同位素效应”，它们对抗体的亲和力可能降低；β发射体的计数更昂贵且困难；并非所有类固醇都有3H示踪剂。2. 125I。a) 优点：γ计数更便宜、更简单且更精确；125I示踪剂对抗体的亲和力可能高于未标记的类固醇；125I可用于标记任何类固醇。b) 缺点：125I示踪剂的保质期有限（注意，125I组胺示踪剂为六个月）。如果未标记的类固醇不能有效竞争，一些示踪剂的高亲和力将成为一个很大的缺点。
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