Radioimmunoassay procedure

Body fluids are analyzed for T and T by a variety of radioimmunoassay procedures (31) (see Immunoassays). The important clinical parameter for estimating thyroid function, the protein-bound iodine (PBI), is measured as described in treatises of clinical chemistry. High performance Hquid chromatographic (hplc) methods have replaced dc (32,33). 

The level of radioactivity encountered in the usual radioimmunoassay procedures is low enough so that liquid wastes may be disposed of in the sink with running water. In calculating the amount of radioactive material that may be disposed of via the sewage system from one building, one must know the water usage. This may be obtained from the water bill. The allowable quantity of in sewage is 4.0 x 10" /ii Ci/ml of water... 

Where specific drugs have been demonstrated to Interfere with chemical reactions, patients should be maintained free of these drugs for at least 72 hours before collecting the specimen. Other analytical techniques, e.g. column chromatography and radioimmunoassay procedures, can also be substituted for an affected method. 

In a radioimmunoassay procedure, 1 pmol of labelled analyte was added to the sample. Antiserum equivalent to 75 pmol of analyte was then added, and after incubation the bound and free fractions separated by precipitation with ammonium sulphate solution. The activity ratio, bound free, was measured to be 2.88. Calculate the number of moles of analyte in the original sample. 

The stereospecificity of antigen-antibody reactions has gained its due recognition more than half-a-century ago. However, an intensive and extensive stereospecificity radioimmunoassay procedures have been adequately applied to a number of pharmaceutical substances since mid-seventies, for instance atropine, propranolol, methadone-to name a few. 

At present few hospital laboratories use gas chromatographic methods because colorimetric, fluorometric, and other spectro-photometric methods can give data more rapidly, are less expensive, and are often of sufficient accuracy and precision for clinical evaluation of the patient. Radioimmunoassay procedures are available, but these are limited because of availability of the necessary antibodies and a sufficient demand to justify the expense of setting up the laboratory. For versatility and adaptability, many different analyses can be done on a single gas chromatograph. The only requirement is the proper column and choice of operating conditions. Furthermore, the techniques, in many cases, are now automated. The utility of GC coupled with... 

The TSH radioimmunoassays procedures have replaced other methods for the quantitative assessment of changes in pituitary responsiveness after repeated dose treatment, test compounds which enhance the secretion of thyroid hormones lead to a suppression of the serum TSH concentrations, a clinical example being hyperthyroidism (Connors et al. 1981, Pekary et al. 1980). On the other hand, a reduction in circulating concentrations of thyroid hormones (T3 and T4) will release the pituitary gland from feedback inhibition, and the serum concentration of TSH may arise in an exponential manner. 

Matejczik, R. J., Kosinski, J. A., Determination of Cross-Reactant Drugs with a New Morphine Radioimmunoassay Procedure, J. Forensic Sci., 30, 677,1985. 

Figure 8-39. Competition of various steroids with radioactive deoxycorticosterone (DOC) for binding to DOC-specific antiserum. These data were generated by standard radioimmunoassay procedures. (Courtesy of New England Nuclear Corp., Worcester, Mass.)...

Both the ammonium sulfate and anti-immunoglobulin techniques have been used not only to measure the presence or the concentration of antibody, but to detect very small amounts of antigen in fluids or solutions. (Discussions and applications of the various radioimmunoassay procedures referred to here are given elsewhere in this volume.)... 

Some rather novel chemistry was described in two recent very interesting papers describing a radioimmunoassay procedure for ADP-ri-bose. Adenine-A -carboxymethylated NAD was prepared and converted to A -carboxymethylated ADP-ribose by NAD glycohydrolase. A -Carboxymethylated ADP-ribose was then linked to BSA using water-soluble carbodiimide. 

Fig. II. Beads that have been completely processed in the radioimmunoassay procedure and are about to be dropped into small test tubes, then placed in a gamma counter for reading (the last step in the assay).

Determination of the distribution of Ag between the antibody-bound and free fractions, in radioimmunoassay procedures, requires a separation step which isolates Ag from Ag -Ab. Once separated, measurement of the radioactivity of the label in one or both the fractions provides a signal that is approximately exponentially related to the concentration of unlabeled antigen. The graphical relationship can have either a positive or a negative slope depending on whether the antibody-bound or free fraction is measured. The exact shape of the calibration curve however, is dependent on the antibody-binding equilibrium constant. ... 

Kubasik NP, Ricotta M, Hunter T, et al. Effect of duration and temperature of storage on serum analyte stability Examination of 14 selected radioimmunoassay procedures. Chn Chem 1982 28 164-5. 

Production of using BARC reactors began in 2003 with neutron irradiation of natural xenon gas in a special arrangement of the Dhruva reactor. A carefully standardized procedure was developed within the BARC involving one week of irradiation of gas (4 g at 10 atm) in a 70 mL sealed capsule. To minimize the formation of 1 (which is not suitable for radioimmunoassay procedures), a short period of irradiation at medium flux using large volumes of xenon gas is desirable. Chemical processing is done in accordance with standard procedures. 

Arnaud and Littledyke (A5) and Hargis et al. (HI) overcame the problem of antigenicity by conjugating relatively pure porcine thyro-calcitonin to rabbit albumin before injection, and claim that the antisera obtained were specific to thyrocalcitonin, judged by gel diffusion and immunoelectrophoresis results. The former workers have briefly described the use of this antiserum in a radioimmunoassay procedure similar to that devised by Berson et al. for parathormone (B4). They claim that the technique will detect 0.5 ng of thyrocalcitonin/ml of serum. These workers found no difference in the immunological behavior of human and porcine hormone, and quote a normal range of 30-85 ng/ml in human plasma. In animal studies, elevated values were found in older animals and in response to hypercalcemia. 

Highly purified h-TSH and b-TSH showed no cross reactivity by gel diffusion methods and radioimmunological precipitation techniques (U2). However, in several bioassay procedures limited cross reactivity has been shown between anti-b-TSH antibodies (L4, M9, U2) and human TSH. A radioimmune assay described by Lemarchand-Beraud (L2) is based on the use of anti-b-TSH antibodies developed in rabbits. Recently cross reactivity has been reported between h-TSH and antibodies to porcine TSH (F9). Radioimmunoassay procedures were used in these studies. It would appear that there may be two groups of antigenic sites on human TSH, one specific and one shared in common with b-TSH and p-TSH. 

GF Read, D Riad-Fahmey. Determination of a tricyclic antidepressant clomipramine anafranil in plasma by a specific radioimmunoassay procedure. Clin Chem 24 36, 1978. 

CE Cook, CR Tallent, EW Amerson, MW Myers, JA Kepler, GF Taylor, HD Christensen. Caffeine in plasma and saliva by a radioimmunoassay procedure. J Pharmacol Exp Ther 199 679, 1976. 

KK Midha, et al. Development of a radioimmunoassay procedure for mesoridazine and its comparison with a high performance liquid chromatographic method. Ther Drug Monit 9 464, 1987. 

RG Stoll, MS Christensen, E Sakmar, et al. The specificity of the digoxin radioimmunoassay procedure. Res Commun Chem Pathol Pharmacol 4 503, 1972. 

JT Slusher, et al. Intracellular zidovudine (ZDV) and ZDV phosphates as measured by a validated combined high pressure liquid chromatography radioimmunoassay procedure. Antimicrob Agents Chemother 36 2473, 1992. 

J English, J Chakraborty, V Marks, A Parke. A radioimmunoassay procedure for dexamethasone plasma and urine levels in man. Eur J Clin Pharmacol 9 239, 1975. 

ES Lo, et al. Direct radioimmunoassay procedure for plasma dexamethasone with a sensitivity at the picogram level. J Pharm Sci 78 1040, 1989. 

New insights into the kinetics of binding and repair of carcinogen-DNA adducts are being accumulated through new techniques of detecting small quantities of adducts by radioimmunoassay procedures 68, 62) Thus, for example, AAF-DNA adducts can now be detected by such methods with DNA extracted from livers of rats given even low doses of dietary AAF (Poirier, True, and Laishes, unpublished observations). 

Radioimmunoassay procedures for the drug in plasma and urine have been developed utilizing a polyclonal antiserum produced to a conjugate in which lisinopril is linked to albumin via a dinitrophenylene bridge (2,31) or succinoylated keyhole limpit haemocyanin (32). In the former procedure, the radiolabel was introduced via radio-iodination of a p-hydroxybenzamidine derived from lisinopril, whereas in the latter procedure, the radiotracer was prepared by acylation of the epsilon amino group of the lysyi side chain of lisinopril with N-succinimidyl-(2,3- H)-proprionate. The limit of sensitivity for the RIA procedures is approximately 0.2-0.4 ng/ml (0.5-1 nM). 

A radioimmunoassay procedure has been used to estimate the small amounts of link-protein that remain associated with the proteoglycan after purification. Partially degraded hyaluronic acid, immobilized on a support of macro-porous agarose, has been used to isolate two link-proteins from crude cartilage extracts. ... 

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