Radioreceptor assays sensitivity

L.E. Llewellyn, A.P. Negri, J. Doyle, P.D. Baker, E.C. Beltran and B.A. Neilan, Radioreceptor assays for sensitive detection and quantitation of saxitoxin and its analogues from strains of the freshwater cyanobacterium, Anabaena circinalis, Environ. Sci. Technol., 35 (2001) 1445-1451. 

The properties of membranes can also be used for analytical purposes. A radioreceptor assay for somatomalin A has been developed using human placental membrane. This assay is more sensitive and simpler than the chick bioassay and requires only 40 pi of serum. It is not species-specific... 

R. F. Metcalfe, A sensitive radioreceptor assay for atropine in plasma, Biochem. Pharmacol, 30 209-212 (1981). 

A Ishii, et al. Sensitive radioreceptor assay of the calcium antagonist benidipine hydrochloride in plasma and urine. Arzneim-Forsch. 38 1733, 1988. 

NM Cintron, et al. A sensitive radioreceptor assay for determining scopalamine concentration in plasma and urine. J Pharm Sci 76 328, 1987. 

L Stoll, et al. A simple but highly sensitive radioreceptor assay for the determination of scopolamine and biperiden in human plasma. Res Commun Chem Path Pharmacol 64 59, 1989. 

Creese I and Snyder S, H. (1977) A simple and sensitive radioreceptor assay for antischizophrenic drugs in blood Nature 270,ISO-182. 

Enna S. J and Snyder S. H (1976) A simple, sensitive and specific radioreceptor assay for endogenous GABA in brain tissue / Neurochem 26,221-224... 

Gould R. )., Murphy K. M., and Snyder S H (1983) A simple sensitive radioreceptor assay for calcium antagonist drugs Life Sci 33,2665-2672. 

In general, conventional extraction procedures can be used to prepare samples for analysis by radioreceptor assay. However, since some solvents may influence the binding assay, it is essential that preliminary tests be performed to rule out nonspecific interactions. In most cases, however, the sensitivity of the radioreceptor assay is such that the sample to be analyzed is sufficiently diluted to be rendered inactive in this regard. 

Since the kinetics of receptor binding, and therefore the sensitivity of a radioreceptor assay, may vary with tissue concentration or incubation conditions, it is prudent to calculate a standard curve for the displacement of radioligand during each experiment. To this end, the amount of radioligand bound in the presence and absence of various concentrations... 

The sensitivity of a radioreceptor assay is primarily dependent on two factors, one of which is the affinity of the receptor for the radioligand. Thus, if 20% displacement of pH]-GABA is taken as the least amount that can accurately be determined, the sensitivity of the radioreceptor assay for GABA, as illustrated in Fig. 2, is approximately 10 pmol using a 2 ml incubation volume. If the receptor affinity could be increased tenfold, then the concentration of GABA necessary to inhibit 20% would also be reduced a similar amount, making for a more sensitive assay. 

Enna, S. J., 19806, Radioreceptor assay a simple, sensitive, and specific analytical tool, in Receptor Binding Techniques (D. Bylund, ed.), pp. 257-271, Society for Neuroscience, Washington, D.C. 

Innis, R. B., Bylund, D. B., and Snyder, S. H., 1978, A simple, sensitive, and specific radioreceptor assay for P-adrenergic antagonist drugs. Life Sci. 23 2031-2038. 

Lesniak, M.A., Gorden, P., Roth, J., Gavin, J.R., III Binding of I-human growth hormone to specific receptors in human cultured lympho- 193. cytes. Characterization of the interaction and a sensitive radioreceptor assay. J. biol. Chem. 249, 1661-1667 (1974)... 

In the main this application deals with the analysis of plasma or semm for 25-OH-D3 and 1,25-(0H)2D3, two analytes which are present at low concentrations (25-OH-D3 1,25-(0H)2D3) in a relatively complex medium. It would appear at first sight that this presents a very difficult analytical challenge requiring the most extensive purification prior to quantitation. In the routine clinical laboratory, methods which are time-consuming and technically difficult are not as valuable as simpler and possibly, but not always, less specific methods. There is often a need in clinical situations for speed and simplicity and because of this, a considerable amount of development has taken place to produce simple and convenient assays in kit form, which depend upon the specificity of the saturation analysis quantitation procedure. The result is a method which couples solid-phase extraction with a radioreceptor assay which is both sensitive and specific. LC-MS meth-... 

The studies on the insulin receptor of human lymphocytes led to the development of a sensitive radioreceptor assay which complements the radioimmunoassay in measuring minute quantities of substances in plasma with insulin bioactivity. Using this technique clinically, a patient with a primary defect in insulin receptor deficiency was reported . In the same study, acquired and reversible receptor deficiency was also observed in obese patients . In the obese-hyperglycemic mutant mouse, insulin-resistance appears to correlate directly with an irreversible deficiency in insulin receptor activity on the adipocyte and hepatocyte plasma membranes. Cuatrecasas and his co-workers, on the other hand, reported the same number of insulin-binding sites in adipocytes from obese and insulin-resistant rats as were present in those from normal animals They proposed that the metabolic defect in these animals resides in the coupling of the signals of the insulin-receptor complex to glucose transport. 

G Caselli, et al. Determination of nuvenzepine in human plasma by a sensitive 3H-pirenzepine radioreceptor binding assay. J Pharm Sci 80 173, 1991. 

Estimation of amino acid levels by radioreceptor binding techniques is a relatively new approach. The chapter on this topic reviews the underlying principles of ligand binding assays and details the practical considerations fundamental to the successful utilization of these techniques. Although this type of assay is extremely sensitive, it is beset with problems of specificity, and only one amino acid (GABA) can currently be determined accurately by the method Future developments should, however, extend its applicability to some of the other ammo acids, but it is likely to remain a method for determining a parhcular ammo acid, rather than one to be utilized for the measurement of a spectrum of ammo acids. 

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