Radio-labeled binding studies

The MIPs have also been utilized as the recognition elements in pseudoimmunoassays. " In this approach, MIPs are substituted for antibodies to quantify the amount of analyte in a biological sample, such as blood plasma. Most MIP immunoassays are competitive binding studies in which a radio- or fluorescent-labeled analyte is added to a mixture of the MIP and imlabeled analyte. After equilibrium is reached, some fraction of the labeled species is bound to the polymer surface and thus can be separated from the supernatant. The supernatant is then analyzed via scintillation or fluorescence techniques to determine the concentration of the original unlabeled analyte. Mosbach et al. have demonstrated that MIP-based immunoassays can rival the selectivity of antibody-based assays. Imprinted polymers for the opioid receptor ligands enkephalin and morphine were prepared and showed submicromolar (pM) level selectivity in a radioligand competition assay in aqueous buffers. The analysis... 

Towards this end, studies were carried out which included the radio-labelling of the somatostatin receptor ligand DOTA-Tyr -TATE (1,4,7,10-tetraazacyclotetradecane-N,N, N",N" -tetraacetic acid tyrosineS-octreotate, or DOTATATE) with both Lu and I, and the quality control of the resulting complexes. In vitro studies of the biological affinity of the Lu-DOTATATE and I-DOTATATE for the somatostatin membrane receptor were carried out with the help of competition and saturation binding assays. In vivo studies of the biodistribution of Lu-DOTATATE and I-DOTATA TL in animals, either alone or in competition, were also carried out. The radiotherapeutic effect of "Lu-DOTATATE was evaluated by cytometry measurements. Estimation of absorbed doses of Lu-DOTATATE was carried out by mathematical modelling. 

The availability of synthetic LTs and their corresponding radio-labeled analogs has made the study of both receptor and binding site interactions possible. Schild analysis of FPL 55712 antagonism provided evidence for two distinct receptors for LTD, in the GP trachea. " ... 

Techniques for quantitative ADME typically employ radiolabeled drugs to look at tissue distribution either in homogenized samples or by whole body autoradiography. Whole body autoradiography involving the location and quantification of radiolabeled material in thin frozen sections of tissue can be particularly useful. Plasma protein binding and metabolism studies also benefit from the use of radio-labeled material. 

Previous studies have shown that the phenanthridinone derivative, PJ 34, has a high affinity for PARP-1 (42). PJ 34 inhibits PARP-1 by competing for the NAD binding site in the activated form of the enzyme. Therefore, a radio-labeled version of PJ 34 should be able to measure the hyperactivation of PARP-1 that occurs in the early stages of necrosis. 

Subsequent experiments with radio- and fluorescent-labeled Ad vectors revealed evidence for decreased binding to the apical membrane of these polarized airway epithelial cells as compared to pooriy differentiated airway cells, and a low rate of vector internalization out of proportion to the reduction in binding (78,81,82). Preferential transduction of polarized WD airway epithelia following basolateral application of vector as compared to the apical application was consistent with the binding and uptake smdies (78,81,82). Immimofluorescent antibody studies ultimately localized CAR to the basolateral membrane (54). 

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