Radioimmunoassay of Testosterone-Estradiol-Binding Globulin in Humans: A Reassessment of Normal Values*

Cheng, C. Yan; Bardin, C. Wayne; Musto, Neal A.; Gunsalus, Glen L.; Cheng, Su‐Li; Ganguly, Manik

doi:10.1210/jcem-56-1-68

Cited by 67 publications

(12 citation statements)

References 34 publications

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“…2, indi¬ cate a good correlation (r = +0.98) between the two methods. This also confirms the previous results obtained by RIA (Mercier-Bodard et al 1979;Khan et al 1982;Cheng et al 1983), and suggests that the assay method is not the main reason for the discrepancies among earlier reports on the normal blood levels of SBP. Fig.…”

Section: Resultssupporting

confidence: 91%

Variation with age in the levels of sex-steroid-binding plasma protein as determined by radioimmunoassay

Maruyama¹,

Aoki²,

Suzuki

et al. 1984

Acta Endocrinologica

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A radioimmunoassay for human sex-steroidbinding plasma protein (SBP) was developed. With this assay, SBP was determined in sera of 138 normal men and 169 non-pregnant women, ranging in age from 11 to 87 years. The results indicate (i) that SBP levels in both sexes increase gradually with age up to mid-eighties, (ii) that the average levels in mid-eighties are approximately twice those in early twenties, and (iii) that the average levels in women are about twice as high as those in men of corresponding age. These results may also account for the discrepancies in the previous papers regarding the normal blood levels and sexual difference of SBP in adult men and women.Human plasma contains a protein which binds testosterone and oestradiol with high affinity and for which more than ten names have been pro¬ posed, such as sex-steroid-binding plasma protein (SBP), testosterone-oestradiol-binding globulin, sex-hormone-binding globulin and others (Heyns 1977). A large number of clinical studies relating the SBP levels to various physiological and patho¬ logical conditions has been published (Anderson 1974;Heyns 1977;Bardin et al. 1981; Siiteri et al. 1982). During the course of these studies, a variety of techniques was developed to assay SBP, all of which based on the same principle, i.e., the satura¬ tion of specific binding sites with radioactive testos¬ terone or 5a-dihydrotestosterone followed by se¬ paration and measurement of the specifically bound steroids. However, estimated serum levels of SBP in normal men and women vary over a 2-to 3-fold range, depending upon the method used. This lack of agreement seems to be mainly due to the difference in correcting for the non-specific binding, although other factors, such as sensitivities of the methods and unavailability of pure SBP for assay standardization, can not be neglected.Thus, it is important to use a method which is free from interference of co-existing steroids. The present study was initiated to develop a radioim¬ munoassay (RIA) of SBP and to determine the actual levels of normal men and women of various age. The results described in this paper indicate that RIA for SBP is not affected by co-existing steroids and that SBP levels increase with age not only in men but in women up to mid-eighties.During the course of this study, three reports have appeared describing the similar RIA for human SBP(Mercier-Bodardetal. 1979; Khanetal. 1982;Cheng et al. 1983). Materials and MethodsHuman SBP was isolated from pooled plasma by affinity chromatography on testosterone-17a-ethynylcarboxyamino-ethyl Sepharose 4B followed by hydroxyapatite column chromatography essentially as previously des¬ cribed for bovine, canine, and rabbit SBPs (Suzuki et al. 1977(Suzuki et al. , 1981. This procedure produced a SBP preparation, purified 6000-fold over pooled plasma with

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Section: Resultssupporting

confidence: 91%

Variation with age in the levels of sex-steroid-binding plasma protein as determined by radioimmunoassay

Maruyama¹,

Aoki²,

Suzuki

et al. 1984

Acta Endocrinologica

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“…SHBG Competition Binding Assay-An SHBG competition binding assay was run based upon published methods (38,39) with modifications. Briefly, human blood was collected in Vacutainer SST tubes (BD Biosciences) and kept at room temperature for 30 min before centrifugation at 1,000 ϫ g for 10 min (4°C).…”

Section: Methodsmentioning

confidence: 99%

Molecular and Pharmacological Properties of a Potent and Selective Novel Nonsteroidal Progesterone Receptor Agonist Tanaproget

Zhang

Olland

Zhu

et al. 2005

Journal of Biological Chemistry

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Progesterone receptor (PR) agonists have several important applications in women's health, such as in oral contraception and post-menopausal hormone therapy. Currently, all PR agonists used clinically are steroids. Because of their interactions with other steroid receptors, steroid-metabolizing enzymes, or other steroid-signaling pathways, these drugs can pose significant side effects in some women. Efforts to discover novel nonsteroidal PR agonists with improved biological properties led to the discovery of tanaproget (TNPR). TNPR binds to the PR from various species with a higher relative affinity than reference steroidal progestins. In T47D cells, TNPR induces alkaline phosphatase activity with an EC 50 value of 0.1 nM, comparable with potent steroidal progestins such as medroxyprogesterone acetate (MPA) and trimegestone (TMG), albeit with a reduced efficacy (ϳ60%). In a mammalian two-hybrid assay to measure PR agonist-induced interaction between steroid receptor co-activator-1 and PR, TNPR showed similar potency (EC 50 value of 0.02 nM) and efficacy to MPA and TMG. Importantly, in key animal models such as the rat ovulation inhibition assay, TNPR demonstrates full efficacy and an enhanced progestational potency (30-fold) when compared with MPA and TMG. Furthermore, TNPR has relatively weak interactions with other steroid receptors and binding proteins and little effect on cytochrome P450 metabolic pathways. Finally, the three-dimensional crystal structure of the PR ligand binding domain with TNPR has been delineated to demonstrate how this nonsteroidal ligand achieves its high binding affinity. Therefore, TNPR is a structurally novel and very selective PR agonist with an improved preclinical pharmacological profile.

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“…Briefly, 5 g of BSA (RIA grade, 68 kDa; Sigma, St. Louis, MO) was radioiodinated by Iodogen [35] using 1 mCi of [ 125 I]-sodium iodide (Amersham Pharmacia Biotech) as described elsewhere [36].…”

Section: Intratesticular Injection Of Occludin Peptide and Histologicmentioning

confidence: 99%

A 22-Amino Acid Synthetic Peptide Corresponding to the Second Extracellular Loop of Rat Occludin Perturbs the Blood-Testis Barrier and Disrupts Spermatogenesis Reversibly In Vivo1

Chung

Mruk

et al. 2001

Biology of Reproduction

109

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When Sertoli cells were cultured in vitro on Matrigel-coated bicameral units, the assembly of the inter-Sertoli tight junction (TJ) permeability barrier correlated with an induction of occludin expression. Inclusion of a 22-amino acid peptide, NH(2)-GSQIYTICSQFYTPGGTGLYVD-COOH, corresponding to residues 209-230 in the second extracellular loop of rat occludin, at 0.2-4 microM into Sertoli cell cultures could perturb the assembly of Sertoli TJs dose-dependently and reversibly. This peptide apparently exerts its effects by interfering with the homotypic interactions of two occludin molecules between adjacent Sertoli cells at the sites of TJs, thereby disrupting TJs, which, in turn, causes a decline in transepithelial electrical resistance across the Sertoli cell epithelium. When similar experiments were performed using a 22-amino acid myotubularin peptide, NH(2)-TKVNERYELCDTYPALLAVPAN-COOH (residues 156-177), no effects on the assembly of inter-Sertoli TJs in vitro were noted. When a single dose of this synthetic occludin peptide was administered to adult rats intratesticularly at 1.5-10 mg/testis, germ cells began to deplete from the seminiferous epithelium within 8-16 days. By 27 days, virtually all tubules were devoid of germ cells. This antispermatogenic effect was reversible, because germ cells progressively repopulated the epithelium thereafter. Treated testes were indistinguishable from normal or control testes by 68 days post-occludin peptide treatment when assessed using histological analysis. In contrast, control rats receiving either no treatment, vehicle alone, or a 22-amino acid synthetic peptide of myotubularin displayed no changes in the testicular morphology at all time points. The occludin peptide-induced germ cell depletion was also accompanied by a disruption of the blood-testis barrier (BTB) when assessed by micropuncture techniques quantifying [(125)I]-BSA in rete testis fluid and seminiferous tubular fluid following i.v. administration of [(125)I]-BSA through the jugular vein. These results illustrate that the occludin peptide-induced disruption of the BTB may possibly affect the underlying adherens junctions, which causes premature release of germ cells from the epithelium and reversible infertility.

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Radioimmunoassay of Testosterone-Estradiol-Binding Globulin in Humans: A Reassessment of Normal Values*

Cited by 67 publications

References 34 publications

Variation with age in the levels of sex-steroid-binding plasma protein as determined by radioimmunoassay

Variation with age in the levels of sex-steroid-binding plasma protein as determined by radioimmunoassay

Molecular and Pharmacological Properties of a Potent and Selective Novel Nonsteroidal Progesterone Receptor Agonist Tanaproget

A 22-Amino Acid Synthetic Peptide Corresponding to the Second Extracellular Loop of Rat Occludin Perturbs the Blood-Testis Barrier and Disrupts Spermatogenesis Reversibly In Vivo1

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