Assay radioimmunoassays

Biomedical analytical chemistry happens to be one of the latest disciplines which essentially embraces the principles and techniques of both analytical chemistry and biochemistry. It has often been known as clinical chemistry . This particular aspect of analytical chemistry has gained significant cognizance in the recent past by virtue of certain important techniques being included very much within its scope of analysis, namely colorimetric assays, enzymic assays, radioimmunoassays and automated methods of clinical analysis. 

The article concluded HPLC has now become an important analytical tool to determine structure and purity and is now considered to be a more precise measurement of potency than the rabbit assay, although most government regulatory agencies around the world still emphasize the rabbit potency assay.. .. In the end, we employed 12 different tests to establish that what we had produced was human insulin. We believe that correlation among three of the tests was particularly important—the radioreceptor assay, radioimmunoassay, and HPLC. ... 

The most common types of assays employed to quantitate protein concentrations in biological matrices are listed in Table 32.4. Enzyme-linked immunosorbent assays (ELISAs), radioimmunoassays (RIAs), and immunoradiometric assays (IRMAs) require protein-specific antibodies, labeled proteins, or labeled antibodies as reagents, and are generally competitive inhibition assays. Radioimmunoassays measure concentrations by displacing ligands from cell-bound receptors. The most common assay, the... 

Eiizyme-Iinked immunosorbent assay Radioimmunoassay Immunoradiometric assay Radioreceptor assay... 

Competitive Binding Assays Radioimmunoassay and Enzyme Immunoassay... 

Assay of cyclic nucleotides by enzymatic cycling techniques Protein binding assay Protein kinase assay Radioimmunoassay... 

Analytical techniques used to quantify either total or individual bile acids in biological fluids include gas-hquid chromatography (GLC), high-performance liquid chromatography (HPLC), enzymatic assay, radioimmunoassay (RIA), enzyme-linked immunosorbent assay (ELISA), and tandem mass spectrometry (MS/MS). 

Digestibility assays Serial dilution assays Radioimmunoassay Endpoint methods... 

William Harvey human whole blood assay. Radioimmunoassays of TXBj and PGE2 used as a measure of COX-1 rmd COX-2 activities (Warner TD et al. Proc Natl Acad Sci. 1999 96 7563)... 

Lovelace JL, Kusmierz JJ, Desiderio DM. Analysis of methionine enkephalin in human pituitary by multi-dimensional reversed-phase high-performance liquid chromatography, radioreceptor assay, radioimmunoassay, fast atom bombardment mass spectrometry, and mass spectrometry-mass spectrometry. J Chromatogr 1991 562 573-84. 

The six most commonly used analytical techniques are biological assays, radioimmunoassays, radiochromatography after incubation of tissues in vitro with arachidonic acid, gas chromatography/mass spectrometry (GC-MS), gas chromatography with electron capture detection and recently, high performance liquid chromatography (HPLC). The last is used... 

Medroxyprog esteroneAcetate. Accurate pharmacokinetic and metaboHsm studies on MPA have been difficult because the radioimmunoassays employed caimot differentiate between MPA and its metaboHtes (346). Comparison of MPA plasma levels assayed by hplc and radioimmunoassay show that radioimmunoassay may overestimate intact MPA concentrations by about fivefold (347). However, values of the mean elimination half-life of MPA were similar, being 33.8 and 39.7 h when measured by hplc and radioimmunoassay, respectively (347). Approximately 94% of MPA in the blood is bound to albumin (348). When taken orally, MPA is rapidly absorbed with Htde or no first-pass metaboHsm (13). Peak semm levels ate reached after 3 h. Steady state occurs after three days of daily adininistration (349). The pharmacokinetics of MPA when adininistered in a depot formulation have been described (350). 

The immunochemical interaction between the antigen and antibody is very specific. By labeling either the antigen or antibody, the method s sensitivity is increased. The most frequently used labels to increase sensitivity are radionucHdes (see Radioisotopes) where the assay process is called radioimmunoassay (RIA), or en2ymes where the assay is named en2yme immunoassay (ElA) (see Enzyme applications). 

Specific IgE Assay. Two radioimmunoassays are available in France using a quaternary ammonium compoimd coupled to Sepharose [30, 31]. The sensitivity of these tests was equivalent at 88%, the specificity reaches 90%. A morphine-based immunoassay has been proposed in Australia [14]. More recently, Ebo et al. [32] investigated a rocuronium ImmimoCAP and set the sensitivity at 85%, the specificity being absolute, provided an assay-specific decision threshold is applied. An ImmimoCAP (Phadia A) is available. 

Standard curves performed under our defined radioimmunoassay conditions ([ H]PbTx-3 = 1 nM, antiserum dilution = 1 2000, assay volume = 1 ml) demonstrated the ability of this antiserum to bind equally to PbTx-2 and PbTx-3, suggesting specificity for the cyclic polyether backbone region of the molecule (Figure 8). The linear portion of the curve indicated a lower detection limit of 0.2-0.5 ng in saline buffer under these conditions. Evaluation of this assay for use with biological fluids and tissue extracts is underway. 

Radioimmunoassay is a competitive protein binding assay which utilizes an antibody as the binding protein. This assay also employs a highly purified antigen which has been radio-labeled (tagged). 

This equation illustrates the components of a competitive protein binding assay system. That is, the reaction system contains both radioactive and non-radioactive free ligand (P and P) and both radioactive and non-radioactive protein bound ligand (P Q and PQ). This type of assay assumes that binding protein will have the same affinity for the labeled or non-labeled material that is being measured. Although this assumption is not always completely valid, it usually causes no problems of consequence with most radioassays or radioimmunoassays. 

The counting equipment used to establish quantitation is radioassay and radioimmunoassays may be either a gamma counter or a liquid scintillation counter depending upon the isotope being used. Most assays use as a label and require a... 

Processing for Radioimmunoassays and Immunoradiometric Assays. Clin. Chem. (1974), 1255. 

HPLC, high-petfomtance liquid chromatogtaphy ELISA, enzyme-linked immunosorbent assay method RIA, radioimmunoassay method. 

Assay principle Radioimmunoassay (RIA) Microparticle enzyme immunoassay (MEIA)... 

A variation on the theme of conventional assay uses both lanthanide-labeled and biotin-labeled single strands to form split probes for sequence of target strands (Figure 12).120 When both of these bind to DNA, the complex binds (via the biotin residue) to a surface functionalized with streptavidin, immobilizing the europium and allowing assay to be carried out. This approach is already very sensitive to DNA sequence, since both sequences must match to permit immobilization of the lanthanide, but can be made even more sensitive by using PCR (the polymerase chain reaction) to enhance the concentration of DNA strands. In this way, initial concentrations corresponding to as few as four million molecules can be detected. This compares very favorably with radioimmunoassay detection limits. 

Nowadays, antibodies are utilized in numerous immunoanalytical methods. Those widely used in practice, such as radioimmunoassays, fluoroimmunoassays and enzyme-linked immunosorbent assays (ELISA), require labelled reagents. Millions of ELISA tests for diagnostics of various diseases are daily performed in clinical laboratories. The detection of analytes by two-antibody "sandwich" ELISA, is schematically outlined in Figure 3. 

Since the development of radioimmunoassay (RIA), many assays that rely on the specificity of the antigen-antibody binding reaction have been developed because of their inherent sensitivity and specificity. A typical competitive binding... 

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