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The Endocrine System and Its Disorders
Published in Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss, Understanding Medical Terms, 2020
Walter F. Stanaszek, Mary J. Stanaszek, Robert J. Holt, Steven Strauss
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.
Pregnancy-Related Protein Concentrations During Normal Pregnancy
Published in Gábor N. Than, Hans Bohn, Dénes G. Szabó, Advances in Pregnancy-Related Protein Research, 2020
In sera of nonpregnant controls, PAPP-A can be detected only by extremely sensitive assay methods. Radioimmunoassay methods find 0.05 to 0.1 μg/ml. In men, the serum concentration is similarly 0.05 to 0.1 μg/ml, but the seminal plasma value is significantly higher, 0.6 to 1.6 μg/ml.99
Historical Notes
Published in Albert A. Kurland, S. Joseph Mulé, Psychiatric Aspects of Opiate Dependence, 2019
Albert A. Kurland, S. Joseph Mulé
This chemical test eventually superseded Nalline testing because of its relative simplicity, its lack of hazard, and the frequency with which it could be repeated, if so desired.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].
Impact of chronic maternal stress during early gestation on maternal–fetal stress transfer and fetal stress sensitivity in sheep
Published in Stress, 2018
Michelle Dreiling, Rene Schiffner, Sabine Bischoff, Sven Rupprecht, Nasim Kroegel, Harald Schubert, Otto W. Witte, Matthias Schwab, Florian Rakers
Maternal and fetal stress hormones were sampled at baseline as well as 2, 15, 60, and 120 min after beginning of isolation. Maternal and fetal norepinephrine samples were collected and determined as described previously (Rakers et al., 2015) using high performance liquid chromatography. The method has a detection limit of 5 ng/L−1 norepinephrine (retention time of 0.7 min) with an intra-assay coefficient of variation of 3.9%. Maternal and fetal cortisol was determined by an extraction-free-radioimmunoassay (Cortisol, Coat-A-Count Radioimmunoassay, Diagnostic Products, Los Angeles, CA). The detection limit of the radioimmunoassay is 5 nmol/L−1. For plasma pools measuring 27.6 and 138 nmol/L−1, intra-assay coefficients of variation were 6.9% and 7.0%, respectively. A detailed description of the hormone analysis can be found elsewhere (Rakers et al., 2015).