PubMed · 4185573
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U Fink. 1969-06-06. [Immunosuppressive therapy].. https://pubmed.ncbi.nlm.nih.gov/4185573/
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A piezoelectric (PZ) quartz crystal microbalance (QCM) biosensor for the rapid detection of Vibrio cholerae serotype O139 has been developed. The antibody to this serotype was immobilized on the gold transducer surface of a 10 MHz AT cut PZ crystal. Solutions containing known antigen concentrations were then incubated for 1 h on the antibody-bound transducer. The biosensor was able to detect 10(5) cells per ml of O139 versus a background of O1 (Ogawa) serotype.
Hormones and antihormones induce related, but distinct, conformational changes in the progesterone receptor [Allan, G. F., Leng, X., Tsai, S. Y., Weigel, N. L., Edwards, D. P., Tsai, M.-J. & O'Malley, B. W. (1992) J. Biol. Chem. 267, 19513-19520]. In both cases the conformational change precedes the dissociation of heat shock proteins and binding to DNA. We have now investigated the steps in hormone action which are dependent upon this conformational change. We show that in the absence of ligand, monoclonal antibodies directed against different regions of the progesterone receptor can induce high-affinity binding to its response element in vitro. This antibody-induced DNA binding is presumably facilitated by enhanced dimerization of receptor monomers. However, antibodies do not induce the hormone-specific conformational change in the progesterone receptor and do not induce in vitro transcription by the receptor. In contrast, the antiprogestin ZK98299, which inhibits receptor binding to DNA, fully induces the antihormone-specific conformational change. Thus, our data imply that steroids induce a conformational change in their receptors which is necessary for events subsequent to DNA binding, most likely for transactivation.
The one-step sandwich immunoassay is increasingly replacing the traditional two-step immunoassay due to obvious advantages such as assay speed. However, the one-step sandwich immunoassay suffers from the 'hook' effect irrespective of the analyte characteristics. The 'hook' effect is dependent primarily on the analyte concentration. Three different model analytes, human growth hormone (hGH), the dimeric form of hGH (D-hGH, having a discrete number of repeating epitopes) and ferritin (multiple epitopes) having different immunological properties have been employed in studies of the one-step sandwich immunoassay. The characteristics of each of the model analytes offer new insights into general guidelines for assay procedures. These guidelines permit rapid optimization of assay conditions for an immunoassay without a priori knowledge of the immunological characteristics of the antibody or antigen. Both experimental and theoretical data show several instances where high capacity solid-phase antibodies can effectively shift the 'hook' to relatively higher analyte concentrations. The effect of the concentration of labeled antibody on assay response was examined theoretically.