Testosterone measurement

Oxime derivatization was utilized by Kushnir et al. [44] to improve ESI sensitivity for testosterone measurement. Using a C18 column for separation (3-min run times) and an API 4000 they monitored MRM transitions 304—>124 and 112 for testosterone oxime and 307—>14 and 112 for the d3 internal standard. Within-run and between-run irreproducibility was < 12%. The LOD was 10 pg/ml, allowing accurate measurement of testosterone in women and children. Reference intervals for the steroid in children of different ages and different Tanner stages are given in the publication as well as values for both free and total testosterone. 

Thienpont LM, Van Uytfanghe K, Blincko S, Ramsay CS, Xie H, Doss RC et al (2008) State-of-the-art of serum testosterone measurement by isotope dilution-liquid chromatography-tandem mass spectrometry. Clin Chem 54 1290-1297... 

Dabbs JM, Jr, Campbell BC, Gladue BA, Midgley AR, Navarro MA, Read GF, et al. Reliability of salivary testosterone measurements A multicenter evaluation. Clin Chem 1995 41 1581-4. 

Shirtcliff EA, Granger DA, Likos A. Gender differences m the validity of testosterone measured in saliva by immunoassay. Horm Behav 2002 42 62-9. 

Taieb J, Mathian B, Millot F, Patricot M-C, Mathieu E, Queyrel N, et al. Testosterone measured by 10 immunoassays and by isotope-dilution gas chromatography-mass spectrometry in sera from 116 men, women, and children, Clin Chem 2003 49 1381-95. 

Cawood, M.L., Field, H.P., Ford, C.G., Gillingwater, S., Kiernan, A., Cowan, D. and Barth, J.H. (2005). Testosterone measurement by isotope-dilution liquid chromatography-tandem mass spectrometry validation of a method for routine clinical practice. Clin. Chem., 51, 1472-1479. 

The most complete account of an isotope-displacement method for the ultrasensitive range of testosterone measurements in plasma is that of... 

Figure 3.33 shows a mass spectrum of nonpolar testosterone measured using an APCI interface. As can be seen from the figure, this steroid does not contain basic or acidic functional groups and cannot be ionized by ESI. 

No direct metabolite of testosterone measurable, not detectable via gas chromatographic urine profile. Sodium intake 100-200 meq/d recumbent (m) upright (j) sodium intake 10 meq/d recumbent 333-999 upright 472-3800. 

No direct metabolite of testosterone measurable, not detectable via gas chromatographic urine profile. 

The metabolism of trichloroethylene, as measured by the levels of excreted urinary metabolites, differs significantly between men and women, although study results are inconsistent (Inoue et al. 1989 Kimmerle and Eben 1973b Nomiyama and Nomiyama 1971). It does appear, however, that women excrete more urinary TCA than do men (Kimmerle and Eben 1973b Nomiyama and Nomiyama 1971). Testosterone has been implicated as a factor in the lower absorption of trichloroethylene in male rats compared with females (Kadry et al. 1991b McCormick and Abdel-Rahman 1991), and the same effect may occur in humans. 

Mooradian (1993) has studied the antioxidant properties of 14 steroids in a non-membranous system in which the fluorescence of the protein phycoerythrin was measured in the presence of a lipid peroxyl radical generator (ABAP). Oxidation of the protein produces a fluorescent species. Quenching of fluorescence by a test compound indicates antioxidant activity. Oestrone, testosterone, progesterone, androstenedione, dehydroepian-drosterone, cortisol, tetrahydrocortisone, deoxycorti-... 

Measurements of Pe in fixed-pH solutions but at various different stirring speeds need to be made. The double-reciprocal analysis, HPe versus 1/v , for Caco-2 permeability measurements in the Transwell (Corning Costar) system produced a linear plot for x- 0.8 [514]. The intercept yields the membrane permeability for the particular pH value in the study the slope determines the k constant. From the analysis of testosterone transport, for the stirring speed of 25 rpm (planar rotating shaker), the thickness of each UWL (assuming symmetric geometry) was calculated to be 465 pm at 150 rpm, haq= 110 pm [514], Karlsson and Artursson [512] found x = 1.0 to best represent their stirring-based analysis of the UWL permeability. 

All the stimulating primer effects in mammals analyzed so far share a common hormonal pathway the first measurable event is stimulation of LH-releasing hormone (LHRH) release. This, in turn, stimulates LH levels and leads to increases of estrogens in females and testosterone in males. In females, changes in size and function of uterus and ovaries follow, while males respond... 

An important qualification must be made. While a biomarker may be of proven value in establishing whether a drug has the desired effect in patients or healthy volunteers (see Section 4.6.3) and for evaluation of the dose-response relationship, a biomarker may not be a surrogate for the clinical endpoint. Thus, suppression of testosterone after an initial rise will give an almost immediate endpoint for the effect of GnRH analogues in prostate cancer but the relationship breaks down later in the disease. Measures of blood glucose control are vital... 

Measure serum testosterone levels 14 days after initiation of therapy to ensure proper dosing. If the serum testosterone concentration is below the normal range, or if the desired clinical response is not achieved, the dose may be increased from 5 to 7.5 g AndroGel) or 10 g Testim) and from 7.5 to 10 g AndroGel), as instructed by the physician. 

Figure 3.12 Persistence of testosterone in sandy loam, loam, and silt loam soil spiked with 1 mg [ C]-testostrone/kg. The middle panel shows residues in soil extracts, whereas the bottom panel represents a loss in androgenicity in the soil extract. Androgenicity was measured using a human androgenicity receptor recombinant yeast strain. (Adapted from Lorenzen et al., 2005.)...

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