Control of the misuse of testosterone in castrated horses based on an international threshold in plasma

Presence and detection of endogenous steroids in the horse-A review

Detection of doping with steroids that are also endogenous in the horse can be challenging, and a variety of approaches to distinguish exogenous administration from their natural presence are employed. Knowledge of endogenous concentrations of various steroids in different genders of horses (intact male, castrated male and female) and factors that could naturally affect them is beneficial for establishing ways for detection of their use. The current internationally adopted approaches include concentration-based thresholds in urine and plasma, steroid ratios in urine and targeting the administered intact steroid esters in plasma and hair. However, these have their limitations, and therefore, other strategies, such as additional biomarkers and steroid profiling based on longitudinal testing and multivariate analysis, have been investigated and could potentially improve detection of the use of endogenous steroids in horses. This paper aims to provide a comprehensive overview of the steroids (androgens, oestrogens and progestogens) that have been reported to be endogenous to horses in literature, their concentration ranges in different genders and factors potentially affecting them as well as current and possible future approaches to detect their use.

Endogenous nature of estra-4,9-diene-3,17-dione in entire male horses

Estra-4,9-diene-3,17-dione (dienedione) is an anabolic androgenic steroid (AAS) sold as a bodybuilding supplement. It is prohibited in both human and equine sports. With no report of 4,9-diene configuration in endogenous steroids, dienedione has long been considered a synthetic AAS. Nevertheless, the reoccurring detection of dienedione in colt (entire male horse) urine samples lead to the investigation of its possible endogenous nature in horses. This paper describes (i) the detection of naturally occurring dienedione in colts, (ii) the conjugation study of dienedione and (iii) the population study of free and glucuronide-conjugated dienedione in colt urine. Qualitative and quantitative analyses of dienedione content in colt urine were performed, employing liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Qualitative analyses showed that dienedione was endogenous in colt urine and mainly in the form of glucuronide conjugates. Glucuronidation of dienedione was believed to happen at 3-enol leading to dienedione-3-glucuronide. Upon the population study of free and glucuronide-conjugated dienedione in colt urine samples (n = 175), the mean ± SD was determined to be 2.5 ± 3.5 ng/ml. The population data fitted a normal distribution after a fifth root transformation with the exclusion of one outlier by Grubb's test. A possible in-house threshold was proposed at 30 ng/ml of free and glucuronide-conjugated dienedione in colt urine associated with a risk factor of 1 in 14,269 (with a degree of freedom of 173). This is the first report of endogenous dienedione in entire male horses and the approach for controlling its potential misuse by using a threshold is also presented.

ANPELA: analysis and performance assessment of the label-free quantification workflow for metaproteomic studies

Label-free quantification (LFQ) with a specific and sequentially integrated workflow of acquisition technique, quantification tool and processing method has emerged as the popular technique employed in metaproteomic research to provide a comprehensive landscape of the adaptive response of microbes to external stimuli and their interactions with other organisms or host cells. The performance of a specific LFQ workflow is highly dependent on the studied data. Hence, it is essential to discover the most appropriate one for a specific data set. However, it is challenging to perform such discovery due to the large number of possible workflows and the multifaceted nature of the evaluation criteria. Herein, a web server ANPELA (https://idrblab.org/anpela/) was developed and validated as the first tool enabling performance assessment of whole LFQ workflow (collective assessment by five well-established criteria with distinct underlying theories), and it enabled the identification of the optimal LFQ workflow(s) by a comprehensive performance ranking. ANPELA not only automatically detects the diverse formats of data generated by all quantification tools but also provides the most complete set of processing methods among the available web servers and stand-alone tools. Systematic validation using metaproteomic benchmarks revealed ANPELA's capabilities in 1 discovering well-performing workflow(s), (2) enabling assessment from multiple perspectives and (3) validating LFQ accuracy using spiked proteins. ANPELA has a unique ability to evaluate the performance of whole LFQ workflow and enables the discovery of the optimal LFQs by the comprehensive performance ranking of all 560 workflows. Therefore, it has great potential for applications in metaproteomic and other studies requiring LFQ techniques, as many features are shared among proteomic studies.

Determination of Steroids in Bovine Serum: Validation of a Reliable LC-MS/MS Method and In Vivo Studies with Boldenone Undecylenate and Testosterone Propionate

Serum analysis has received much attention in regulatory analysis of food-producing animals, especially for anabolic steroids. The possibility of confirming the parent drugs with minimum metabolization enables the detection of intact steroid esters, whose identification represents unequivocal proof of drug administration. This work involved the development and validation of a quantitative LC-MS/MS method to determine 30 steroids and steroid esters in bovine serum. Sensitivity was improved using microwave-assisted chemical derivatization with methoxyamine hydrochloride. The validation was successfully conducted in accordance with the Decision 657/2002/EC guidelines. An in vivo experiment was performed on 12 crossbred steers in which two commercial formulations containing boldenone undecylenate and testosterone propionate were administrated via intramuscular injections. The samples were collected over a period of 120 days, in which both intact esters were identified within 11 days postadministration. 17β-Boldenone was observed after 92 days for 2 steers and 56 days for the other animals. The applicability of a cut-off level to the ratio between 17β-testosterone and epitestosterone was evaluated in an attempt to differentiate testosterone abuse from endogenous production. It could be observed that a calculated ratio above this level is strong evidence of drug administration, although a high false-negative rate was obtained.

Monitoring dehydroepiandrosterone (DHEA) in the urine of Thoroughbred geldings for doping control purposes

The use of testosterone and its pro-drugs, such as dehydroepiandrosterone (DHEA), is currently regulated in horseracing by the application of international testosterone thresholds. However, additional steroidomic approaches, such as steroid ratios, to distinguish overall adrenal stimulation from drug administrations and an equine biological passport for longitudinal steroid profiling of individual animals could be advantageous in equine doping testing. Thus, DHEA concentrations and related ratios (testosterone [T] to DHEA and DHEA to epitestosterone [E]) were assessed in the reference population by quantitative analysis of 200 post-race gelding urine samples using liquid chromatography-tandem mass spectrometry. DHEA concentrations ranged between 0.9 and 136.6 ng/mL (mean 12.8 ng/mL), T:DHEA ratios between 0.06 and 1.85 (mean 0.43), and DHEA:E ratios between 0.21 and 13.56 (mean 2.20). Based on the reference population statistical upper limits of 5.4 for T:DHEA ratio and 48.1 for DHEA:E ratio are proposed with a risk of 1 in 10 000 for a normal outlier exceeding the value. Analysis of post-administration urine samples collected following administrations of DHEA, Equi-Bolic® (a mix of DHEA and pregnenolone) and testosterone propionate to geldings showed that the upper limit for T:DHEA ratio was exceeded following testosterone propionate administration and DHEA:E ratio following DHEA administrations and thus these ratios could be used as additional biomarkers when determining the cause of an atypical testosterone concentration. Additionally, DHEA concentrations and ratios can be used as a starting point to establish reference ranges for an equine biological passport.