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Coupled Mass Spectrometic—Chromatographic Systems
Published in Steven H. Y. Wong, Iraving Sunshine, Handbook of Analytical Therapeutic Drug Monitoring and Toxicology, 2017
We have been investigating the direct detection of testosterone and epitestosterone conjugates in urine (Figure 10–10). Positive-ion SIM for epitestosterone glucuronide gives detection limits of 25 pg on-column when packed capillary HPLC columns are used, and lower detection limits for epitestosterone sulfate, testosterone sulfate, and testosterone glucuronide.101 Interestingly, we found that the epitestosterone glucuronide partially fragmented in the interface region before entering the mass spectrometer, giving rise to the protonated aglycone. Because the mass of the intact molecule was monitored, this resulted in an apparent decrease in response for epitestosterone glucuronide. The glucuronide conjugate of epitestosterone was much more labile than that of testosterone, even though the two compounds are epimers. Thus, careful investigation of the operating parameters of the HPLC/MS system is imperative to achieving success in HPLC/MS.
The Biochemistry of the 17-Hydroxysteroid Dehydrogenases
Published in Ronald Hobkirk, Steroid Biochemistry, 1979
In general, steroid metabolic pathways involving the 17α-hydroxysteroid dehydrogenases are those which result in inactivation and excretion of the C18 and C19 steroid hormones. In ruminants, the rabbit, and the dog, 17β-estradiol is converted to the 17a-epimer prior to excretion in the urine.10 Epitestosterone has been identified in human urine by several researchers.83–86
A long-term follow-up study of men born with very low birth weight and their reproductive hormone profile
Published in Systems Biology in Reproductive Medicine, 2018
Mats Hammar, Erika Larsson, Marie Bladh, Orvar Finnström, PO Gäddlin, Ingemar Leijon, Elvar Theodorsson, Gunilla Sydsjö
Testosterone in hair was measured using a competitive radioimmunoassay in speedvaced methanol extracts of homogenized hair. The radioligand was 125I labelled testosterone-3-CMO-histamine and rabbit antiserum (T4276, Sigma Aldrich) was used which crossreacts 23.0, 1.5, 0.2, and 1.7% for 5α-dihydrotestosterone, 17α-epitestosterone, dehydroepiandrosterone, and androstenedione, respectively. The calibrator was testosterone (Sigma Aldrich T5411) verified with a European pharmacopoeia reference standard (EDQM, Strasbourg, France). All hair samples were analyzed in the same assay, the intra-assay CV % for testosterone in hair was 9.6% at 10 pg/ml, 3.0% at 45 pg/ml, and 2.9% at 90 pg/ml.
Effect of morphology and support of copper nanoparticles on basic ovarian granulosa cell functions
Published in Nanotoxicology, 2020
Alexander V. Sirotkin, Monika Radosová, Adam Tarko, Iris Martín-García, Francisco Alonso
The cross-reactivity of antiserum against testosterone was ≤3.3% with 11β-hydroxytestosterone and 19-nortestosterone, ≤0.9% with androstenedione, ≤0.8% with 5α-dihydrotestosterone, <0.1% with 17α-methyltestosterone, epitestosterone, 17β-estradiol, progesterone, cortisol, estrone, and danazol. The maximal intra- and inter-assay coefficients of variation were 4.16 and 4.73%, respectively. Sensitivity of the assay was 0.083 ng/mL.