title: Milk progesterone radioimmunoassay using radioiodinated tracers: a rapid and reliable assay system.
abstract: Both the validity and practicability of a direct progesterone radioimmunoassay based on radioiodinated progesterone tracers were studied. The results obtained show the reliability of the assay; when compared with assays based on 3H-progesterone tracers there are fewer steps for assay execution, saving time and reducing the number of reagents used. Various commercially available 125I-progesterone tracers were assayed, and only those with an 11 alpha-hemisuccinate bridge were suitably bound by antisera raised against progesterone-bovine serum albumin conjugates having identical bridge structure. The bridge effect caused no observable alteration in validity parameters. Finally, our results support the utility of this assay as a practical method of early diagnosis of pregnancy and as a reliable experimental technique to monitor cow ovarian function.
mesh_terms: D000818:Animals; D000915:Antibody Affinity; D002417:Cattle; D004971:Estrus; D005260:Female; D007457:Iodine Radioisotopes; D008892:Milk / Q000032:analysis*; D010053:Ovary / Q000502:physiology; D011247:Pregnancy; D011259:Pregnancy Tests, Immunologic / Q000662:veterinary*; D011374:Progesterone / Q000032:analysis*; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D007457:Iodine Radioisotopes; D011374:Progesterone