Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Epitestosterone”

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 73 records · Page 4Linked to original sources
PubMed2005

Extraction of testosterone and epitestosterone in human urine using aqueous two-phase systems of ionic liquid and salt.

Based on aqueous two-phase systems (ATPS) consisting of 1-butyl-3-methylimidazolium chloride, a hydrophilic ionic liquid (IL), and K2HPO4, a new and simple extraction technique, coupled with a reversed-phase high performance liquid chromatography (RP-HPLC), was developed for the simultaneous concentration and analysis of testosterone (T) and epitestosterone (ET) in human urine. Under the optimal conditions, the extraction efficiencies for both analytes were 80-90% in a one-step extraction. The method required only 3.0 mL of urine and a single hydrolysis/deproteinization/extraction step followed by direct injection of the IL-rich upper phase into HPLC system for analysis. The method has been satisfactorily applied to the analysis of T and ET in human urine with detection limits of 1 ng/mL and linear ranges of 10-500 ng/mL for both compounds. Compared with conventional liquid-liquid extraction or solid phase extraction, this new method is much "greener" due to no use of volatile organic solvent and low consumption of IL. The proposed extraction technique opens up new possibilities in the separation of other drugs.

Chemical Fractionation↗
PubMed1996

High doses of alcohol increase urinary testosterone-to-epitestosterone ratio in females.

The effect of alcohol (1.2 and 2.0 g/kg) on the urinary testosterone-to-epitestosterone (T/E) ratio was studied by two experiments each conducted with four healthy females and males. The intake of 2.0 g/kg of ethanol within 5 h in the evening significantly increased plasma testosterone concentration and ratio of T/E in urine collected next morning in females. The results suggest that alcohol increases the T/E ratio more in females than in males. The effect of high doses of alcohol on urinary T/E ratio must be kept in mind when doping tests are performed during training periods.

Adrenal Glands↗
PubMedDate not supplied

Development and method validation for testosterone and epitestosterone in human urine samples by liquid chromatography applications.

An isocratic high-performance liquid chromatographic method for the determination of testosterone (T) and epitestosterone (ET) in human urine using liquid-liquid or solid-phase extraction (SPE) is developed and validated. The optimum separation is achieved using a Hypersil C(18) column, water-acetonitrile (57:43, v/v) as the mobile phase and UV-absorbance detection at 245 nm. The recoveries obtained for T and ET in liquid-liquid and SPE demonstrate that these procedures are interchangeable. Quantitation limits for T and ET are 8.6 and 5.4 ng/mL using solvent extraction and 7.3 and 5.7 ng/mL using SPE, respectively. The proposed method is used to evaluate the urinary T, ET, and the T/ET ratio for a healthy male population using liquid-liquid extraction, and the T and ET excretion profile for nine healthy men using SPE.

Adult↗
PubMed1989

Dehydroepiandrosterone and epitestosterone in the blood of cows at term.

From Day 268 of gestation till two days after parturition blood samples were collected from the jugular vein of 5 cows with normal and 4 cows with flumethasone induced parturition and centrifuged immediately after sampling. In another experiment blood samples were taken from the jugular and uterine vein of 3 cows during the last week before normal parturition. The dehydroepiandrosterone (DHA) and epitestosterone (ET) concentrations in plasma were measured using radioimmunoassay. In the control group the DHA concentration was in the range of 2 to 5 nmol/l, ET levels varied from 4 to 8 nmol/l before term. In both groups, there was an increase in DHA concentrations during the last periparturient period whereas ET levels increased only after flumethasone induced parturition. The concentrations of both androgens declined after the expulsion of the placenta and they were higher in the uterine vein than in the jugular vein. It is concluded, that both androgens are secreted by the bovine placenta and that the delta 5-pathway of steroidogenesis is active in vivo.

Animals↗
PubMed1981

Plasma levels of androstenedione, epitestosterone, testosterone and oestrogens in cows at parturition.

The concentration of total unconjugated oestrogens in the peripheral plasma of cows increased from 2.00 +/- 0.20 (S.E.M.) ng/ml 7 days before to 3.87 +/- 0.50 ng/ml 1 day before parturition and declined to values below 0.30 ng/ml on day 2 post partum. The concentrations of androstenedione, epitestosterone and testosterone remained approximately constant at 0.90 +/- 0.10, 0.92 +/- 0.08 and 0.40 +/- 0.20 ng/ml respectively during the last week of pregnancy. After parturition the concentration of the three androgens declined rapidly. Similar to data obtained in goats we did not find a marked increase in androgen levels in the peripheral blood of cows before parturition.

Androstenedione↗
PubMed1994

The effect of epitestosterone on gonadotrophin synthesis and secretion.

The effects of 3-week treatment with increasing doses of epitestosterone (ET) on gonadotrophin gene expression and secretion, on testosterone and 5 alpha-dihydrotestosterone (DHT) levels, and on the weight of testes and prostates, were studied in intact adult male rats. The hormones were delivered by means of silastic capsules of different lengths filled with the steroid. One group of rats received testosterone (T) instead of ET, to compare the results with previous studies concerning the testosterone effect. The controls were given capsules with glucose only. Treatment with ET, as well as with T, significantly reduced the weights of prostates. When the data from ET-treated rats and controls were combined, a significant negative correlation (P < 0.001) was found between the weight of prostates and serum ET. T, in contrast to ET, also decreased significantly the weights of testes, ET treatment caused a significant reduction of serum T levels but only an insignificant decline of DHT levels, independent of the dose. Serum and pituitary (p) luteinizing hormone (LH) levels in the ET-treated rats did not change. Pituitary mRNA contents for the beta LH subunit (beta LH-mRNA) showed a dose-dependent significant increase, up to 170% (P < 0.01), with ET treatment. pFSH decreased with the lowest ET (2 cm) dose (P < 0.05), but no change was observed with the other doses. The mRNA for the common alpha-subunit also increased with the ET load. In conclusion, ET acts at several sites in the regulation of gonadotrophin formation and release. It enhances the steady-state mRNA levels of both gonadotrophins in the pituitary.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

[Detection of self-administration of testosterone as an anabolic by determination of the ratio of urinary testosterone to urinary epitestosterone in adolescents].

Testing for illicit self-administration of testosterone by athletes requires quantitative analysis by gas chronomatography-mass spectrometry combined with stable isotope dilution. International Sports Authorities have adopted the ratio of urinary excretions of testosterone and epitestosterone for drug testing. This ratio is required to be under 6. The authors studied the statistical distribution of this ratio in teenage athletes and found that the likelihood of false-positive results is 15/10,000.

Adolescent↗
PubMed1988

Effect of ethanol on the ratio between testosterone and epitestosterone in urine.

The testosterone/epitestosterone weight ratio in urine is used to detect cases of doping when an athlete has treated himself with exogenous testosterone. When this ratio exceeds 6, it is considered evidence of testosterone doping. We show here that intake of ethanol can affect this ratio. Ingestion of 110-160 g of ethanol, about 2 g per kilogram body weight, increased the ratio between testosterone and epitestosterone in urine from 1.14 +/- 0.07 to 1.52 +/- 0.09 in four healthy male volunteers. The increase ranged from 30% to 90% in the different subjects studied (mean 41%). In cases where doping with testosterone is suspected, the possibility should be considered that at least part of an observed increased testosterone/epitestosterone ratio in urine is ascribable to previous ingestion of ethanol.

Adult↗
PubMed1981

[Extrarenal excretion of epitestosterone in the adult male].

Twentyfour hour-urinary 17-oxo-steroids (17 KS), epitestosterone (ET) and testosterone (T) were measured before and after a 5-day-HCG-stimulation test performed in 65 healthy male volunteers aged 30 to 76 years. Subjects whose basal urinary T was higher than average physiological values showed a lower increase (p less than 0,001) in ET excretion rate after HCG stimulation than the rest of the casuistry. Neither T nor 17 KS increase after HCG stimulation showed any significant differences in the two subgroups. As ET behaves differently as compared both to the typical testicular androgen, and to the testicular-adrenal metabolites, the adrenal glands may not be the only nor even the main source of ET in the urine of healthy men.

17-Ketosteroids↗
PubMed1994

Detection of simultaneous self-administration of testosterone and epitestosterone in healthy men.

Combined self-administration of testosterone (T) and epitestosterone (ET) by athletes counteracts the efficiency of the corresponding urinary glucuronides (G) ratio, (T/ET)G, as an indicator of T abuse. I therefore propose 5-androstene-3 beta, 17 alpha-diol (5A3 beta 17 alpha), the immediate metabolic precursor of ET, as a new reference compound for the expression of relative excretions of T and ET. Thus (T/5A3 beta 17 alpha)G and (ET/5A3 beta 17 alpha)G become potential criteria to indicate joint administration of T and ET, since their respective threshold values (2.5 and 1.5) are exceeded even when (T/ET)G remains below the critical value of 6.

Adolescent↗
PubMed1997

Detection of anabolic steroid administration: ratio of urinary testosterone to epitestosterone vs the ratio of urinary testosterone to luteinizing hormone.

Our goal in this study was to determine whether the urinary ratio of testosterone to luteinizing hormone (T/LH) as an indicator of exogenous anabolic steroid (AS) use is superior to the urinary ratio of testosterone to epitestosterone (T/E). After 2 weekly placebo injections, 19 subjects were given testosterone cypionate (TC) injections of 250 or 500 mg/week for 14 weeks followed by 14 weekly placebo injections. Patients were considered to have ceased taking TC if they tested negative 9 weeks after their last injection. For detection of illicit or supraphysiological TC (AS) use, the urinary T/E ratio of > or = 6 yielded a false-negative rate of 46% and a false-positive rate of 4%. However, a urinary T/LH ratio of > or = 30 produced a false-negative rate of only 24% and a false-positive rate of 13%. We conclude that the urinary T/LH ratio of > or = 30 is a more sensitive marker of AS use than the urinary T/E ratio of > or = 6 and remains sensitive for twice as long as urinary T/E.

Adolescent↗
PubMed2005

Characterization of 17alpha-hydroxysteroid dehydrogenase activity (17alpha-HSD) and its involvement in the biosynthesis of epitestosterone.

BACKGROUND: Epi-testosterone (epiT) is the 17alpha-epimer of testosterone. It has been found at similar level as testosterone in human biological fluids. This steroid has thus been used as a natural internal standard for assessing testosterone abuse in sports. EpiT has been also shown to accumulate in mammary cyst fluid and in human prostate. It was found to possess antiandrogenic activity as well as neuroprotective effects. So far, the exact pathway leading to the formation of epiT has not been elucidated. RESULTS: In this report, we describe the isolation and characterization of the enzyme 17alpha-hydroxysteroid dehydrogenase. The name is given according to its most potent activity. Using cells stably expressing the enzyme, we show that 17alpha-HSD catalyzes efficienty the transformation of 4-androstenedione (4-dione), dehydroepiandrosterone (DHEA), 5alpha-androstane-3,17-dione (5alpha-dione) and androsterone (ADT) into their corresponding 17alpha-hydroxy-steroids : epiT, 5-androstene-3beta,17alpha-diol (epi5diol), 5alpha-androstane-17alpha-ol-3-one (epiDHT) and 5alpha-androstane-3alpha,17alpha-diol (epi3alpha-diol), respectively. Similar to other members of the aldo-keto reductase family that possess the ability to reduce the keto-group into hydroxyl-group at different position on the steroid nucleus, 17alpha-HSD could also catalyze the transformation of DHT, 5alpha-dione, and 5alpha-pregnane-3,20-dione (DHP) into 3alpha-diol, ADT and 5alpha-pregnane-3alpha-ol-20-one (allopregnanolone) through its less potent 3alpha-HSD activity. We also have over-expressed the 17alpha-HSD in Escherichia coli and have purified it by affinity chromatography. The purified enzyme exhibits the same catalytic properties that have been observed with cultured HEK-293 stably transfected cells. Using quantitative Realtime-PCR to study tissue distribution of this enzyme in the mouse, we observed that it is expressed at very high levels in the kidney. CONCLUSION: The present study permits to clarify the biosynthesis pathway of epiT. It also offers the opportunity to study gene regulation and function of this enzyme. Further study in human will allow a better comprehension about the use of epiT in drug abuse testing; it will also help to clarify the importance of its accumulation in breast cyst fluid and prostate, as well as its potential role as natural antiandrogen.

Amino Acid Sequence↗