Radioassay for serum and red cell folate.
Radioassay for serum and red cell folate.
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血清和红细胞叶酸的放射测定。
DOI：
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发表时间：
1976
期刊：
影响因子：
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通讯作者：
V. Herbert
中科院分区：
文献类型：
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作者：
D. Longo;V. Herbert
本文介绍了一种简便、可靠的血清和红细胞叶酸测定方法。它使用未经处理的普通液体或奶粉作为粘合剂，无需特殊处理或纯化。这样的奶使得可以忽略内源性血清叶酸结合剂，因为粗（但未纯化）奶含有从血清结合剂释放叶酸的因子。它通过采用蝶酰谷氨酸（PGA）的γ发射同位素，即PGA的125 I-酪胺，简化了放射性计数。与Givas和Gutcho的3 H-PGA测定类似，其允许使用稳定的PGA而不是不稳定的甲基四氢叶酸（MeTHFA）标准品，因为其在pH 9.3下进行，在该pH下，乳汁叶酸结合剂无法区分PGA和MeTHFA，后者是人体组织中的主要叶酸。大多数诊断化学实验室都有进行放射性分析所需的设备。结果基本上与公认的干酪乳杆菌叶酸测定微生物学方法相同，不同之处在于抗生素、镇静剂和化疗剂在放射性测定中不会产生假低结果。在使用中有三个注意事项：与3 H-PGA相比，125 I-PGA相对不稳定;各种奶粉的叶酸结合能力差别很大;只有大约60%的商业脱脂或奶粉制品似乎含有将叶酸从血清结合剂中分离出来的物质。
A simple, reliable assay for serum and red cell folate is described. It uses plain untreated liquid or powdered milk, requiring no special handling or purification, as binder. Such milk makes it possible to ignore endogenous serum folate binder, since crude (but not purified) milk contains a factor which releases folate from serum binder. It simplifies counting radioactivity by employing a gamma emitting isotope of pteroylglutamic acid (PGA), namely the 125I-tyramide of PGA. Like the 3H-PGA assay of Givas and Gutcho, it permits the use of stable PGA rather than unstable methyltetrahydrofolic acid (MeTHFA) standards, because it is carried out at pH 9.3, a pH at which milk folate binder is unable to distinguish PGA from MeTHFA, which is the predominat folate in human tissues. The equipment required to do the radioassay is present in most diagnostic chemistry laboratories. Results are essentially identical to the generally accepted Lactobacillus casel microbiologic method of folate assay, except that false low results are not produced in the radioassay by antibiotics, tranquilizers, and chemotherapeutic agents. Three caveats in its use are the relative instability of 125I-PGA as compared to 3H-PGA, the fact that various powdered milks differ widely in folate-binding capacity, and that only about 60 per cent of commercially obtained skim or powdered milk preparations appear to contain the substance which splits folate from serum binder.