The measurement of oestrone-3-glucuronide in urine by non-competitive idiometric assay

Immunoenzymometric Assay for a Small Molecule,11-Deoxycortisol, with Attomole-Range Sensitivity Employing an scFv−Enzyme Fusion Protein and Anti-Idiotype Antibodies

“…This is the lowest detection limit for steroid immunoassays that has been reported to date. The detection limit of noncompetitive steroid assays, such as idiometric assays for estradiol, estrone-3-glucuronide, or progesterone, is estimated to be in the femtomole range, while the metatype-based assay for digoxin 36 exhibited a somewhat higher sensitivity. To our knowledge, only a noncompetitive assay for [Arg 8 ]-vasopressin ( M r 1084.2), reported by Hashida et al ., provided a higher sensitivity determining a hapten than our present method (detecting 1 amol of hapten) .…”

“…metatype antibody" specifically recognizing the complex of a target hapten and the cognate antibody. [35][36][37] We chose to develop a noncompetitive assay for 11-DC 19 and the bile acid metabolites, ursodeoxycholic acid 7-N-acetylglucosaminides, 38,39 based on the principle [40][41][42][43] that was called idiometric assays. 41 These assays are based on the selective capture of hapten-anti-hapten immune complexes by an R-type anti-idiotype antibody that binds to the framework of the anti-hapten antibody regardless of whether it is occupied or not occupied with the relevant hapten.…”

“…These techniques could obtain assay sensitivities greater than 1000-fold higher than those of conventional competitive assays 29,30 and greater than 100-fold higher than that of our previous idiotypeanti-idiotype-based 11-DC assay system. 19 Although the present IEMA system employs the combination of R-and β-type antiidiotype antibodies with a "hapten-binding protein" (i.e., scFv-ALP) as in previous idiometric assays, [41][42][43] the β-type antibody was used only to separate immune complexes from unoccupied scFv-ALP molecules, not to saturate (inactivate) unoccupied scFv-ALP molecules. The use of half-area microtiter plates also facilitated the reactions to take place at higher antigen and antibody concentrations as well as the use of AttoPhos fluorogenic substrate, which also might have contributed to the high sensitivity seen in this assay.…”

Recent Progress in Noncompetitive Hapten Immunoassays: A Review

“…Since the establishment of this method, Barnard's group has applied it to the detection of estradiol (Barnard & Kohen, 1990;Barnard et al, 1991;Mares et al, 1995) and progesterone (Barnard et al, 1995a) in serum and Estrone-3 Glucuronide (Barnard et al, 1995b) in urine， Kobayashi et al have applied it to the detection of UDCA 7-NAG (a bile acid metabolite) (Kobayashi et al, 2000;Kobayashi et al, 2003 a) and 11-deoxycortisol (Kobayashi et al 2003 b). More recently, Niwa et al (2009) established a noncompetitive-type ELISA for cortisol based on idiometric assay model.…”