Radiotracers For Nonimaging Studies: II
Garimella V. S. Rayudu, Lelio G. Colombetti in Radiotracers for Medical Applications, 2019
Body composition of certain elements may be measured by in vivo neutron activation and whole body counting techniques but these are used in a very limited manner. Among the in vitro techniques where radionuclides are used widely for sensitive and specific measurement of circulating hormones and enzymes, radioimmunoassay methodology is unparalleled in its scope, versatility, and sensitivity. This review presents an attempt to focus on the application of nonimaging radionuclidic methodology, taking into consideration the conditions cited above. A list of the radionuclides utilized for nonimaging studies along with their physical properties is given in Table 1 and the modes of productions are tabulated in Chapter 7 (Volume II), Appendix II and in Chapter 3 (Volume I).
The Endocrine System and Its Disorders
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss in Understanding Medical Terms, 2020
The basic screening tests used in initial evaluation of thyroid function include TT4 by radioimmunoassay (RIA), resin T3 uptake (RT3U or RT4U), free thyroxine index (FT.,1), thyroid-stimulating hormone (TSH) measurement, and free serum thyroxine (FT4). The term thyroid scan is often encountered, referring to administration of a radioactive compound and visualized by a scanner device. These procedures are often supplemented by a number of additional tests available for assessment of thyroid functions. For example, an exophthalmometer is used to measure the extent of protrusion of the eyeball. Thy roglobulin, the colloid protein secreted by the thyroid gland, is elevated when the thyroid is inflamed or enlarged; this can be measured in the serum by radioimmunoassay. Cholesterol levels can also be measured to determine a possible association with thyroid disorder.
Historical Notes
Albert A. Kurland, S. Joseph Mulé in Psychiatric Aspects of Opiate Dependence, 2019
This chemical test eventually superseded Nalline testing because of its relative simplicity, its lack of hazard, and the frequency with which it could be repeated, if so desired. Studies comparing urine analysis with the nalorphine test utilizing TLC followed,88 indicating its lack of hazard and the superiority of the urine testing. Subsequently, even more sensitive chemical tests were developed for detecting drugs in urine employing increasingly sophisticated analytical procedures that could be rapidly performed. Among these, the use of the radioimmunoassay was of particular importance.89 These methods, because of their increased sensitivity, detected more morphine-positive urines than the thin-layer chromatographic procedures. However, the choice of any analytical technique or method for detection of drugs of abuse must consider the purpose for which the analysis is performed, e.g., routine screening, toxicology, medico-legal, or hospital emergencies.
Peptidomic analysis in the discovery of therapeutically valuable peptides in amphibian skin secretions
Published in Expert Review of Proteomics, 2019
J. Michael Conlon, Milena Mechkarska, Jérôme Leprince
The major disadvantage of methods that involve detection of active components by using bioassays is their low sensitivity. Thus, peptides with antimicrobial activity that may be potentially therapeutically valuable but are present in chromatographic fractions in low concentrations that are below the minimum inhibitory concentration (MIC) will not be detected. Similarly, insulin-releasing peptides that are present in concentrations below the threshold concentration (minimum concentration producing a significant increase in the rate of release) will be missed. This limitation is of particular relevance in investigations involving very small frogs or in the case of rare species when often only a single individual is available for study. In addition, microbiological assays generally require a dedicated laboratory as they cannot be performed in facilities that employ mammalian cell lines due to the high probability of contamination. The use of ELISA kits to detect peptides that stimulate the release of anti-inflammatory cytokines and/or insulin may be prohibitively expensive. Similarly, methods involving radioimmunoassay may be precluded because of prohibition of the use of radioactivity in the investigator’s laboratory.
Optimization of biologic therapy in Crohn’s disease
Published in Expert Opinion on Biological Therapy, 2018
There are several drug assays commercially available to detect serum drug levels and antibodies of biologic therapies. It is important to note that no single drug assay represents a gold standard test for detection of drug levels and antibodies [16]. Enzyme-linked immunosorbent assay (ELISA)-based assays (e.g. LabCorp, Miraca) are used by many institutions due to low cost and ease of use. This technology uses a detection antibody to capture and measure drug molecules contained in serum, and can also detect drug antibodies by using the biologic drug as a capture antigen to pair with a labeled drug antibody [18]. Radioimmunoassay technology uses radiolabeled TNF and TNF antibodies to detect serum drug levels and drug antibodies, respectively [19]. Homogenous mobility shift assay (e.g. Prometheus) uses high pressure liquid chromatography to identify changes in mobility of binded drug and antidrug molecular complexes based on size [20]. There is also a reporter cell-based assay that employs a human cell line with TNF receptors which aids in measuring drug serum levels and antibodies [21].
Evaluating the efficacy of oxytocin for pain management: An updated systematic review and meta-analysis of randomized clinical trials and observational studies
Published in Canadian Journal of Pain, 2023
Anastasia A. Mekhael, Jennifer E. Bent, Jonathan M. Fawcett, Tavis S. Campbell, Aldo Aguirre-Camacho, Alison Farrell, Joshua A. Rash
Oxytocin levels were observed to differ between individuals who experience chronic pain and healthy controls, and these differences appeared to differ based on chronic pain condition. It is important to note that differences have been observed in the bioanalytical method employed to quantify plasmatic oxytocin concentration, with values from radioimmunoassays differing widely from those of enzyme immunoassays.89 Different assay methods may capture molecules other than oxytocin and add to heterogeneity in assessment. Of interest, four studies included in this comparison used radioimmunoassay,61,62,73,74 with the remaining study using enzyme immunoassay.66 Taken together, results suggest that the oxytocinergic system may play a differential role in the development or experience of different pain diagnoses.
Related Knowledge Centers
- Antibody
- Immune Complex
- Immunoassay
- In Vitro
- Sensitivity & Specificity
- Blood
- Antigen
- Radioactive Tracer
- Hormone
- Sensitivity & Specificity
- Immunoradiometric Assay