Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “HEXESTROL”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10Linked to original sources

Regulation of ovarian carbonyl reductase mediated by estrogen receptor in immature rats.

In the present study, the enhancing effect of synthetic estrogen on ovarian carbonyl reductase, a new prostaglandin (PG)-metabolizing enzyme, was investigated, and the antagonistic effect of antiestrogen on this enhancement was examined in immature rats. Ovarian carbonyl reductase activity towards 13,14-dihydro-15-keto-PGF2 alpha (15KD-PGF2 alpha), 4-benzoylpyridine (4BP) and menadione was determined photometrically and radiochemically, and quantitation of ovarian carbonyl reductase content was performed by Western blot analysis. Diethylstilbestrol (DES) and hexestrol (HX) enhanced the increasing effect of human chorionic gonadotropin (hCG) on ovarian carbonyl reductase activity and content when these synthetic estrogens (0.2 mg/kg) were administered for 3 days from 26 days of age, before hCG treatment. On the other hand, tamoxifen, which inhibits the binding of estradiol to the estrogen receptor, significantly prevented estradiol (E2) from enhancing the effect of hCG on ovarian carbonyl reductase. Furthermore, the ovarian carbonyl reductase activities towards the three substrates correlated well with the ovarian carbonyl reductase content. These results indicate that ovarian carbonyl reductase in immature rats may be regulated by a specific increase in the ovarian response to luteinizing hormone mediated by estrogen receptor.

Alcohol Oxidoreductases↗

Activation by human chorionic gonadotropin of ovarian carbonyl reductase in mature rats exposed in vivo to estrogens.

We investigated the effects of exogenous estrogens and human chorionic gonadotropin (hCG) on the activity, content, and immunohistochemical localization of ovarian carbonyl reductase (CR) in mature cycling rats. Estrogens, estradiol, hexestrol (HEX) and diethylstilbestrol (DES) were given s.c. to rats daily for 3 days from the first day of diestrus, and hCG was given s.c. at 3:00 p.m. on the day of expected proestrus. The ovaries were isolated on the day of expected estrus. Ovarian CR activity was measured by using two substrates that reflect the activity of the enzyme in rats, and the enzyme content was determined by western blot analysis. Ovarian CR activity and content were decreased by estrogens as well as by inhibition of ovulation; hCG restored both the activity and the content decreased by estrogens to levels produced by hCG alone. Nevertheless, the number of ova in the oviduct when ovulation was decreased or blocked by estrogens was not restored completely by hCG treatment. Faint immunostaining in the interstitial gland cells of HEX-treated rat ovaries was observed. These results suggest that (i) although hCG activates ovarian CR in estrogen-treated rats, this increase in both enzyme activity and content may not be an obligatory event in the ovulatory process, and (ii) exogenous estrogens may predominantly influence the ovarian CR in the interstitial gland cells in mature rats by inhibiting luteinizing hormone release from the pituitary.

Alcohol Oxidoreductases↗

Peroxidase-mediated binding of diethylstilbestrol analogs to DNA in vitro: a possible role for a phenoxy radical.

In order to investigate the role of peroxidase-mediated metabolic activation in the mechanism of carcinogenicity of diethylstilbestrol (DES), a series of 14C-labelled analogs of DES was synthesized and their binding to DNA upon oxidation by peroxidases from horseradish or mouse uterus was studied in vitro. The compounds chosen for this study were the erythro and threo form of hexestrol (HES), the E,E- and Z,Z-isomer of dienestrol (DIES) and the mono- and dimethyl ether of DES. Non-extractable binding to DNA was observed for all compounds with at least one free hydroxyl group independent of the stilbene structure. The extent of binding was highest for the HES isomers and for E,E-DIES, whereas Z,Z-DIES and the monomethyl ether were bound to about the extent of DES. These findings imply that the formation of a phenoxy free radical is sufficient for non-extractable DNA binding and the stilbene structure is not required for peroxidase-mediated activation of DES.

Animals↗

Drug residue analysis using immunoaffinity chromatography.

The background and applicability of immunoaffinity chromatographic separations and clean-up to drug residue analysis of agricultural commodities is discussed. The uses of antibody specificity for separation and concentration of drug residues are presented. Examples of immunoaffinity chromatography for the determination of residues of (1) nortestosterone and methyl testosterone in swine muscle, urine and bile; (2) chloramphenicol in swine tissue, eggs and milk; (3) clenbuterol in calf urine; (4) zeranol and beta-zearalanolin in calf urine: (5) diethylstilbestrol, dienestrol and hexestrol in calf urine are presented. Further, examples of the successful coupling of immunoaffinity separations with other chromatographic techniques such as gas chromatography and high-performance liquid chromatography are presented.

Animals↗

In vivo and in vitro estimations of the direct effect of estrogen on rat hepatocytes tested by the changes in the unusual estrogen-binding protein content.

The direct effect of estradiol (E2) on the hepatocytes of mature male rats has been examined by measuring the changes in the unusual estrogen-binding protein (UEBP) content and parallel measuring the level of liver estrogen receptors (ER). The content of UEBP (NUEBP) and ER (NER) in the liver were determined using the quantitative methods for differential specific determination of the E2-binding sites of these proteins. It has been shown that the administration of E2 in vivo induced a considerable decrease in hepatic NUEBP not only in intact males, but also in hypophysectomized males during the initial period after the operation (when the content of hepatic ER was still high) and produced no effect in hypophysectomized males during the later period (when liver ER were depleted). Repeated administration of human growth hormone (hGH) (twice a day) resulted in a considerable increase in NER in hypophysectomized males and restored the sensitivity to the subsequent inhibitory effect of E2 on UEBP. We also used rat hepatocytes after a 4-day primary culturing. These cells had a stable morpho-functional status, high ER level, and sex-differentiated UEBP content. Culturing of mature male rat hepatocytes in the medium containing E2 at concentrations close to physiological levels (10(-10)-10(-7) M) decreased NUEBP in a dose-dependent manner. Hexestrol (10(-7) M) but not cholesterol (10(-5) M) also exhibited a direct effect on NUEBP in cultured rat hepatocytes. The effect of E2 was reversible: statistically significant increase in NUEBP was observed 3 days after 10(-9) M E2 had been removed from the culturing medium. It was concluded that hepatocytes may be a primary target for E2 under physiological conditions and that GH may modulate the direct effect of E2 at the hepatic level by modifying the content of liver ER.

Animals↗

Specific cytosol binding of diethylstilbestrol in rat skeletal muscle.

Rat skeletal muscle cytosol proteins bound 3H-diethylstilbestrol (3H-DES). More than 90% of this binding was high capacity and low affinity. Serum albumin accounted for roughly 50-60% of the binding, as evidenced by its precipitation with anti-rat albumin IgG. About half of the binding was distinguishable from albumin and other serum proteins by its precipitation in 40% saturated ammonium sulfate. This material sedimented at 4-5S in high-salt sucrose gradients, and resolved into two components (8S and 4-5S) in low-salt. Following incubation at 23-27 degree C for one hour, 2% of the bound 3H-DES in whole cytosol (approximately 2 fmole/Mg cytosol protein) was retained by DNA cellulose, and was eluted with 0.6 M KCl. This small fraction of the total binding was inhibited by estrogens and DES analogues: estradiol-17 beta, DES, dienestrol, and hexestrol were strong inhibitors; isodienestrol, dimethylstilbestrol, estradiol-17 alpha, estrone, tamoxifen, MER-25, CI-628, and nafoxidine were weak inhibitors; dihydrotestosterone, testosterone, and prednisone did not compete. These observations indicate that specific estrogen-binding sites exist in rat skeletal muscle.

Ammonium Sulfate↗

Biotransformation, estrogenicity, and steroid structure as determinants of dysmorphogenic and generalized embryotoxic effects of steroidal and nonsteroidal estrogens.

A series of nine chemicals of varying structure and estrogenicity was investigated for biochemical determinants of their relative capacities to alter normal embryonic growth and developmental patterns during organogenesis in rats. In order to circumvent the potentially confounding influences of maternal factors, the direct effects of steroidal and nonsteroidal estrogens on cultured whole embryos were compared at concentrations producing readily measurable embryotoxicity but low embryolethality (2-20%). Nonsteroidal estrogens included were diethylstilbestrol (DES), hexestrol (HES), E,E-dienestrol (alpha-DIES), and tamoxifen (TAM). Steroidal estrogens were estradiol 17 beta (E2), estrone (E1), and 17 alpha-ethinylestradiol 17 beta (EE). For comparative purposes, the effects of two essentially nonestrogenic phenols, Z,Z-dienestrol (beta-DIES) and phenol, were also studied. TAM, a weak estrogen which also exhibits antiestrogenic properties, was studied for possible interactive effects with potent estrogens. Prosencephalic hypoplasia was the abnormality most consistently observed and was elicited by each of the chemicals investigated. Embryotoxicity was neither attenuated by TAM nor related to estrogenic potency or steroidal structure, but was strongly and unpredictably influenced by biotransformational determinants. Presence of a cytochrome P450-dependent oxidizing system in the culture medium resulted in marked increases in embryotoxicity of E1, E2, and phenol, only minor increases for beta-DIES and alpha-DIES, but in strikingly decreased effects of EE, TAM, and HES. It produced no statistically significant differences in effects of DES. The results obtained were compatible with the concept that effects of these agents on growth and development during the earlier stages of organogenesis are independent of steroid structure or estrogenic activity but strongly dependent upon pathways and rates of biotransformation of some (but not all) of the parent chemicals.

Abnormalities, Drug-Induced↗

Inhibitory effect of diethylstilbestrol on histamine release by rat mast cells and its relation to the cellular ATP content.

The effect of diethylstilbestrol, a synthetic estrogen, on mast cell secretion was investigated. The results showed that 50 microM diethylstilbestrol inhibited histamine release from rat peritoneal mast cells in the presence and absence of glucose, but did not affect 45Ca uptake stimulated by concanavalin A. Diethylstilbestrol also inhibited histamine release induced by compound 48/80, exogenous ATP, or ionophore A23187. Since estradiol benzoate, hexestrol and daidzein were not inhibitory, the inhibitory action of diethylstilbestrol must be independent of its estrogenic activity. The ATP content of mast cells decreased to less than 0.1 nmol/10(6) cells on treatment with 50 microM diethylstilbestrol at 37 degrees C for 15 min. This effect of diethylstilbestrol in decreasing the ATP content of mast cells correlated well with its inhibitory effect on histamine release. Diethylstilbestrol at 50 microM depleted the cells of ATP at 37 degrees C, but not at 0 degrees C, whereas [3H]diethylstilbestrol ( [monoethyl-3H]diethylstilbestrol) binding to rat mast cells was the same at 0 and 37 degrees C. It is concluded that diethylstilbestrol reduced the ATP content of rat mast cells by inhibiting metabolism of the cells, and consequently inhibited degranulation.

Adenosine Triphosphate↗

Alterations in membrane permeability induced by aminoglycoside antibiotics: studies on liposomes and cultured cells.

Aminoglycoside antibiotics bind to negatively-charged membranes in vitro as well as in vivo. We have examined if this binding could be associated with a change in the properties of membrane permeability. We have used a series of aminoglycoside derivatives and two independent test systems, namely (i) the release of calcein and of Mn2+ from phosphatidylinositol-containing large unilamellar vesicles, and (ii) the influx of Ca2+ into cultured macrophages. We found that certain aminoglycosides (e.g., streptomycin, isepamicin) markedly increase the membrane permeability whereas others (e.g., gentamicin) barely or do not influence it. This increase, when it occurs, is slower or less extensive than observed with pore-forming agents (mellitin, nystatin) or a Ca(2+)-ionophore (ionomycin). It is not observed with an agent [bis(beta-diethylaminoethylether)hexestrol] known to cause membrane fusion, and is not associated with any detectable change in membrane fluidity. In computer-aided conformational analysis of mixed monolayers between phosphatidylinositol and the aminoglycosides studied, it was found that those derivatives inducing an increase in membrane permeability in our experiments adopted an orientation rather perpendicular to the interface, whereas those with no or only a moderate effect were placed in a parallel orientation to this interface. The perpendicular orientation might cause a local condition of disorder which could explain the effects observed.

Aminoglycosides↗

Development and validation of a fluorescence HPLC-based screening assay for inhibition of human estrogen sulfotransferase.

Human estrogen sulfotransferase (SULT1E1) is involved in the regulation of 17beta-estradiol responsiveness and is believed to protect peripheral tissues from excessive estrogenic effects. Several assays already have been developed to investigate the inhibitory effect of endocrine-disrupting compounds (EDCs) on SULT1E1. However, most of these assays make use of the radiolabeled cofactor [(35)S]3'-phosphoadenosine 5'-phosphosulfate (PAPS) or radiolabeled substrate [(3)H]estradiol. In this article, we describe the development and validation of an assay for the inhibition of human SULT1E1 that is rapid and simple and that uses the nonradioactive and noncarcinogenic 1-hydroxypyrene. A gradient HPLC separation of 15 min using a C18-RP column was developed to detect 1-hydroxypyrene and its metabolite pyrene 1-sulfate fluorescently. Time- and protein-dependent formation of pyrene 1-sulfate was investigated, and enzyme kinetics was determined (K(m)=6.4+/-0.8 nM and V(max)=158+/-19 pmol/min/microg SULT1E1). At higher 1-hydroxypyrene concentrations, the assay displayed non-Michaelis-Menten kinetics involving substrate inhibition. IC(50) values have been determined for eight known SULT1E1 inhibitors or competing substrates (17beta-estradiol, 17alpha-estradiol, genistein, 17alpha-ethynylestradiol, estrone, diethylstilbestrol, estriol, and hexestrol) and two previously unknown SULT1E1 inhibitors (zearalenone and dienestrol). The method was demonstrated to be easy, feasible, and highly reproducible for SULT1E1 screening assay inhibition studies.

Chromatography, High Pressure Liquid↗

Separation of structurally related estrogens using isocratic elution pressurized capillary electrochromatography.

In this paper, the pressurized capillary electrochromatography (pCEC) with UV detection was utilized for the separation and determination of three structurally related estrogens, such as diethylstilbestrol (DES), hexestrol (HEX) and dienestrol (DE), which were difficult to be separated by capillary electrophoresis (CE) and HPLC due to their similarity in the structure and charge-to-mass ratios. Experiments were carried out in a commercially available pCEC instrument using a capillary column packed with 3 microm octadecyl silica (ODS). Surfactant sodium dodecyl sulfate (SDS) was introduced in the mobile phase to enhance the speed of analysis. The effective factors on the retention time and separation resolution, such as the applied voltage, supplementary pressure, the pH and the concentration of the buffer solution, the concentration of SDS, and the content of acetonitrile in the mobile phase, were evaluated. Based on the investigation, 31% (v/v) acetonitrile and 69% (v/v) of 10 mmol/L phosphate buffer (pH 6.5) containing 1.0 mmol/L SDS at an applied voltage of -12 kV and a supplementary pressure of 1000 psi were found to be the optimal conditions for pCEC to separate the three estrogens. The method also had been applied to the analysis of fish muscle samples spiked with estrogens.

Chromatography, Micellar Electrokinetic Capillary↗

Rapid yeast estrogen bioassays stably expressing human estrogen receptors alpha and beta, and green fluorescent protein: a comparison of different compounds with both receptor types.

Previously, we described the construction of a rapid yeast bioassay stably expressing human estrogen receptor (hERalpha) and yeast enhanced green fluorescent protein (yEGFP) in response to estrogens. In the present study, the properties of this assay were further studied by testing a series of estrogenic compounds. Furthermore, a similar assay was developed based on the stable expression of human estrogen receptor beta (hERbeta). When exposed to 17beta-estradiol, the maximum transcriptional activity of the ERbeta cytosensor was only about 40% of the activity observed with ERalpha, but the concentration where half-maximal activation is reached (EC50), was about five times lower. The relative estrogenic potencies (REP), defined as the ratio between the EC50 of 17beta-estradiol and the EC50 of the compound, of the synthetic hormones dienestrol, hexestrol and especially mestranol were higher with ER, while DES was slightly more potent with ERbeta. The gestagens progesterone and medroxyprogesterone-acetate showed no response, whereas the androgen testosterone showed a very weak response. The anabolic agent, 19-nortestosterone showed a clear dose-related response with estrogen receptor but not beta. The phytoestrogens coumestrol, genistein, genistin, daidzein, daidzin and naringenin were relatively more potent with ERbeta. Ranking of the estrogenic potency with ER was: 17beta-estradiol >> 8-prenylnaringenin > coumestrol > zearalenone >> genistein >> genistin > naringenin. The ranking with the ERbeta was: 17beta-estradiol >> coumestrol > genistein > zearalenone > 8-prenylnaringen >> daidzein > naringenin > genistin >> daidzin. The hop estrogen 8-prenylnaringenin is relatively more potent with ERalpha. These data show that the newly developed bioassays are valuable tools for the rapid and high-throughput screening for estrogenic activity.

Biological Assay↗

Peroxidase-mediated in vitro metabolism of diethylstilbestrol and structural analogs with different biological activities.

The comparative peroxidative metabolism of diethylstilbestrol (DES) and structurally related compounds of different biological activity was investigated in vitro with horseradish peroxidase (HRP) and hydrogen peroxide (H2O2) as a model peroxidase system: UV spectroscopy revealed the formation of p-quinone intermediates in HRP-H2O2 catalyzed incubations of DES, 3',3",5',5"-tetrafluoro-DES (TF-DES) and dimethylstilbestrol (DMS) and the tautomerization of the quinones to their dien compounds, Z,Z-dienestrol (Z,Z-DIES), tetrafluoro-dienestrol (TF-DIES) and dienmestrol (DIMS) respectively, which were characterized by HPLC and GC/MS. Z,Z-DIES, E,E-DIES, TF-DIES and DIMS were subject to further peroxidative metabolism; however, quinone intermediates were not formed in the HRP-H2O2 containing incubations according to UV spectroscopy. Similarly, hexestrol (HES), 4'-O-methyl-DES (M-DES) and 4',4"-O-dimethyl-DES (DM-DES) did not form quinone intermediates; moreover, they showed little or no apparent metabolic conversion under conditions where DES, TF-DES and DMS were readily peroxidized. However, at a 20-fold higher peroxidase concentration HES and M-DES showed metabolic conversion whereas DM-DES did not.

Carbon Radioisotopes↗

Interaction of the macrolide azithromycin with phospholipids. I. Inhibition of lysosomal phospholipase A1 activity.

Azithromycin, the first clinically developed dicationic macrolide antibiotic, displays an exceptional accumulation in lysosomes of cultured cells. In fibroblasts incubated with 50 mg/l (66.6 microM), it induces a distinct phospholipidosis as evidenced by biochemical and ultrastructural criteria, which strikingly resembles alterations described previously with gentamicin, a pentacationic aminoglycoside antibiotic which inhibits the lysosomal catabolism of phospholipids. We show that both drugs inhibit, in an equimolar manner, the activity of phospholipase A1 (assayed for phosphatidylcholine, included in negatively charged liposomes), in a way consistent with the model of 'charge neutralization' proposed already for gentamicin (Mingeot-Leclercq et al., 1988, Biochem. Pharmacol. 37, 591). Both drugs bind to negatively charged liposomes. Yet, in spite of this binding, azithromycin does not induce aggregation or fusion of negatively charged vesicles, under conditions in which gentamicin (or spermine, a fully hydrophilic polycation) causes a massive aggregation, and bis(beta-diethylaminoethylether)hexestrol (a dicationic amphiphile) causes fusion. The molecular interactions of azithromycin with acidic phospholipids are further examined in a companion paper.

Animals↗

Defined subcomplexes of the A1 ATPase from the archaeon Methanosarcina mazei Gö1: biochemical properties and redox regulation.

The potential A(1) ATPase genes ahaA, ahaB, ahaC, ahaD, ahaE, ahaF, and ahaG from the anaerobic archaeon Methanosarcina mazei Gö1 were overexpressed in Escherichia coli DK8 (pTL2). An A(1) complex was purified to apparent homogeneity and shown by Western blot and N-terminal sequence analyses to contain subunits A, B, C, D, and F but to be devoid of subunits E and G. Further removal of subunit C was without effect on ATPase activity. The enzyme was most active at pH 5.2 and required bisulfite and acetate for maximal activity. Kinetic studies confirmed three new inhibitors for A(1) ATPases (diethylstilbestrol and its derivatives hexestrol and dienestrol) and identified redox modulation as a new type of regulation of archaeal A(1) ATPases.

Adenosine Triphosphatases↗

Determination of residues of anabolic drugs in meat by gas chromatography-mass spectrometry.

The residues in meat of seven estrogenic drugs used in anabolic preparations for animal production were analysed as trimethylsilyl ethers by electron-impact gas chromatography-mass spectrometry following a simple clean-up procedure. The compounds under investigation were: 17 beta-estradiol,l diethylstilbestrol,l hexestrol, dienestrol, stilbestrol, ethynylestradiol and zeranol. The method includes extractive homogenization of 10 g of meat in tetrahydrofuran, followed by liquid-liquid partition between acetonitrile and hexane and finally a chromatographic purification step on a small silica gel column. Gas chromatography was carried out on a 10-m glass capillary column coated with SE-54 using a temperature program from 100 to 250 degrees C. The capillary column was connected to the ion source by an all-glass open-split interface with a scavenger gas-line. Detection of anabolic residues was performed with selected ion monitoring on intensive ions in the mass region above m/e 400, resulting in a detection limit of 1-5 ppb (10(9)). Quantitative determinations were performed using dodecyl gallate as an internal standard applying the signal ratio of the drug and the standard.

Animals↗

Diethylstilbestrol and tetrahydrochrysenes are calcium channel blockers in human platelets: relationship to the stilbene pharmacophore.

The effects of compounds with the stilbene pharmacophore [diethylstilbestrol (DES), DES derivatives, tetrahydrochrysene (THC), and THC derivatives] were examined for their ability to inhibit thrombin-induced Ca(2+) influx in human platelets. DES derivatives (DES dimethyl ether, DES dipropionate, dienestrol, and hexestrol) had lower inhibitory activity than DES. Esterification of DES with the bulky monobenzyl group eliminated inhibitory activity. Unsubstituted THC diol had the lowest inhibitory activity in the series of the THC derivatives bearing substituents in the 5,11 positions. These derivatives, either diethyl or dipropyl, cis or trans, were potent inhibitors of thrombin-induced [Ca(2+)](i) elevation (near 100% inhibition at 10 microM). Therefore, stilbene pharmacophore having bulk out of the plane of the double bond (from the twisting of the two aromatic rings or from addition of all substituents) seems to be requirement for the inhibitory activity. Free hydroxyl groups are also required for inhibitory activity, most likely for hydrogen bonding, since trans-diethyl tetrahydrochrysene dimethyl ether was inactive. Compounds bearing ethyl substituents (DES and THC derivatives) inhibited thrombin-induced release of calcium from the endoplasmic reticulum. These compounds also inhibited thapsigargin-induced Ca(2+) influx. This result implies that these compounds also block store-operated Ca(2+) influx directly, as well as internal Ca(2+) release. Compounds without ethyl substituents (trans-resveratrol, genistein, daidzein, and THC diol) only inhibited calcium influx into platelets.

Adult↗

Simultaneous determination, in calf urine, of twelve anabolic agents as heptafluorobutyryl derivatives by capillary gas chromatography-mass spectrometry.

A method to determine twelve anabolic hormones (diethylstilbestrol, hexestrol, dienestrol, 17 beta-estradiol, 19-nortestosterone, testosterone, 1-dehydrotestosterone, 17 alpha-methyltestosterone, progesterone, estrone, 17 alpha-ethynilestradiol, and trenbolone) is presented. Urine samples were extracted with octadecylsilica columns and clean-up was performed in two steps with basic alumina and silica solid-phase extraction cartridges. The extracts obtained were derivatized with heptafluorobutyric anhydride and analyzed by GC-MS. Stability of derivatives was good and compounds having keto groups produced enol derivatives that were stable also. SIM mode was applied to increase the sensitivity and, when possible, the higher m/z ions were selected to improve identification. Repeatability of the chromatographic analysis was evaluated on the basis of area repeatability, and the coefficient of variation obtained was lower than 13%. Absolute recoveries were in the range 35-60% (dehydrotestosterone and estrone < 20%) with coefficients of variation between 14 and 37% for the whole procedure. [2H3]Testosterone and [2H8]diethylstilbestrol were evaluated to improve quantitative data. The recovery of [2H3]testosterone was found to be equal to or slightly higher than that of the other hormones, but the recovery of [2H8]diethylstilbestrol was lower than any other. [2H3]Testosterone was the most suitable for use as an internal standard, as its addition at the beginning of analytical procedure, corrected recovery results and greatly improved precision. Corrected recoveries from urine ranged from 72-110%, and coefficients of variation ranged from 6-15%, except for testosterone which yielded slightly higher values. The limit of detection was 0.5 ng/ml for all the compounds studied.

Anabolic Agents↗