Performance assessment of an equine metabolomics model for screening a range of anabolic agents

INTRODUCTION

Despite their ban, Anabolic Androgenic Steroids (AAS) are considered as the most important threat for equine doping purposes. In the context of controlling such practices in horse racing, metabolomics has emerged as a promising alternative strategy to study the effect of a substance on metabolism and to discover new relevant biomarkers of effect. Based on the monitoring of 4 metabolomics derived candidate biomarkers in urine, a prediction model to screen for testosterone esters abuse was previously developed. The present work focuses on assessing the robustness of the associated method and define its scope of application.

MATERIALS AND METHODS

Several hundred urine samples were selected from 14 different horses of ethically approved administration studies involving various doping agents' (AAS, SARMS, β-agonists, SAID, NSAID) (328 urine samples). In addition, 553 urine samples from untreated horses of doping control population were included in the study. Samples were characterized with the previously described LC-HRMS/MS method, with the objective of assessing both its biological and analytical robustness.

RESULTS

The study concluded that the measurement of the 4 biomarkers involved in the model was fit for purpose. Further, the classification model confirmed its effectiveness in screening for testosterone esters use; and it demonstrated its ability to screen for the misuse of other anabolic agents, allowing the development of a global screening tool dedicated to this class of substances. Finally, the results were compared to a direct screening method targeting anabolic agents demonstrating complementary performances of traditional and omics approaches in the screening of anabolic agents in horses.

Evidence of complementarity between targeted and non-targeted analysis based on liquid and gas-phase chromatography coupled to mass spectrometry for screening halogenated persistent organic pollutants in environmental matrices

This study explored the complementarity between targeted (TS) and non-targeted screening (NTS) based on liquid and gas-phase chromatography coupled to (high-resolution) mass spectrometry (LC-/GC-(HR)MS) for the comprehensive characterization of organohalogen fingerprints within a set of Lake Ontario lake trout samples. The concentrations of 86 legacy, emerging and novel halogenated compounds (HCs), were determined through 4 TS approaches involving no less than 6 hyphenated systems. In parallel, an innovative NTS strategy, involving both LC and GC-Q-Orbitrap, was implemented to specifically highlight halogenated signals. Non-targeted HRMS data were processed under the HaloSeeker software based on Cl and Br isotopic ratio and mass defect to extend the screening to unsuspected and unknown HCs. A total of 195 halogenated mass spectral features were characterized in the Lake Ontario lake trout, including well known HCs (PCBs, PBDEs, PBBs, DDT and their degradation products), emerging HCs (novel brominated flame retardants, short-, medium- and long-chain chlorinated paraffins) or suggested molecular formula (mainly polychlorinated ones). Among the 122 HCs highlighted by TS, only 21 were identified by NTS. These results fueled a discussion on the potential and limitations of both approaches, and the current position of NTS within environmental and health monitoring programs.

FROM A NON-TARGETED METABOLOMICS APPROACH TO A TARGETED BIOMARKERS STRATEGY TO HIGHLIGHT TESTOSTERONE ABUSE IN EQUINE. ILLUSTRATION OF A METHODOLOGICAL TRANSFER BETWEEN PLATFORMS AND LABORATORIES

In order to overcome the challenge associated with the screening of Anabolic-Androgenic Steroids (AAS) abuses in animal competitions, a non-targeted LC-HRMS based metabolomics approach was implemented on equine urine samples to highlight potential biomarkers associated with the administration of such compounds, using testosterone esters as model steroids. A statistical model relying on 4 potential biomarkers intensity could be defined to predict the status of the samples. With a routine application perspective, the monitoring of the highlighted potential biomarkers was first transferred into high-throughput LC-SRM. The model's performances and robustness of the approach were preserved and providing a first demonstration of metabolomics-based biomarkers integration within a targeted workflow using common benchtop MS instrumentation. In addition, with a view to the widespread implementation of such biomarker-based tools, we have transferred the method to a second laboratory with similar instrumentation. This proof of concept allows the development and application of biomarker-based strategies to meet current doping control needs.

Steroidogenic potential of human fetal kidney at early gestational age

Steroidogenic potential of the human fetal kidney (hFK) at the end of first trimester is poorly investigated. Little is known about the ontogeny of steroidogenic enzymes and activities of steroidogenic pathways in the hFK at early pregnancy. Our aim was to explore steroidogenesis and the expression of steroidogenic enzymes in the hFK at gestational weeks (GW) 9-12. Steroids in the hFK were analyzed by gas chromatography/coupled to tandem mass spectrometry. The expression of steroidogenic enzymes in the hFK at GW 9-12 was investigated by qPCR, automated Western blotting and immunohistochemistry. We observed that the hFK produced substantial amount of steroids of the Δ⁵ and Δ⁴ pathways and several steroid precursors in the biosynthesis of DHT via the backdoor pathway but not DHT itself. The levels of steroids and expression of relevant steroidogenic enzymes (e.g., CYP17A1, HSD3B1, HSD3B2, CYP11B1 and AKR1C4) we significantly higher in the hFK at GW11-12 compared to GW9. We also found the expression of sex steroid receptors (e.g., AR, ERα and ERβ) in the hFK at GW9-12. No sex-dependent differences in the levels of all identified steroids and expression of steroidogenic enzymes in the hFK from male and female fetuses were found. Altogether, our data indicate that the hFK at early pregnancy is steroidogenic organ with potential to synthesize multiple steroids that may play an important role in the formation and development of this organ in humans.

Ontogenesis of human fetal testicular steroidogenesis at early gestational age

The onset of steroidogenesis in human fetal testes (HFT) during the first trimester is poorly investigated. One important unresolved question is the ontogeny of steroidogenic enzymes and formation of steroidogenic pathways in the HFT at early pregnancy. Our aim was to explore steroidogenesis, the expression of steroidogenic enzymes and their maturation in the HFT at gestational weeks (GW) 8-12. Steroids in the HFT were analyzed by gas chromatography/coupled to tandem mass spectrometry. The expression of steroidogenic enzymes in the HFT at GW8-12 was investigated by qPCR, automated Western blotting and immunohistochemistry. We demonstrated that the HFT at GW8-9 produced low level of testosterone via the Δ⁴ pathway and progesterone was the major steroid found in the testicular tissue. In contrast, more mature Leydig cells from the HFT at GW11-12 synthesized high levels of androgens via the Δ⁵ pathway. We also observed a significant upregulation of the expression of StAR, CYP11A1, CYP17A1 and its accessory proteins, P450 oxidoreductase (POR) and cytochrome b5 in the HFT at GW11-12 compared to GW8-9. Altogether, our data suggest that that human fetal Leydig cells differentiate rapidly at the end of the first trimester by acquiring capacity to express high levels of steroidogenic enzymes and switch from the Δ⁴ to the Δ⁵ pathways to synthesize high levels of androgens due to maturation of the CYP17-POR-b5 complex.

The human genital tubercle is steroidogenic organ at early pregnancy

It is generally accepted that androgens produced by fetal Leydig cells (FLC) control proper masculinization of the male external genitalia. Here, we hypothesized that the human genital tubercle (GT) has potential to synthesize androgens independently of FLC at early pregnancy. We observed that human GT of both genders have capacity to synthesize steroids of the Δ⁴, Δ⁵ and alternative pathway of DHT synthesis including the androgen itself. The presence of steroids in the GT was associated with the expression of corresponding steroidogenic enzymes. Levels of steroids and the expression of steroidogenic enzymes were similar in the GT from male and female fetuses. In contrast to the GT, the human fetal testis synthesized DHT from testosterone but not via the alternative pathway. Our findings strongly suggest that the human GT at early pregnancy can synthesize DHT via the alternative pathway, which may play an important role in organogenesis of the urethra.

Occurence of legacy and novel brominated flame retardants in food and feed in France for the period 2014 to 2016

Determination of the occurrence levels of legacy and novel BFRs is today required to better understand the trends of BFRs contamination in food consecutive to the EU PBDEs restrictions and to proceed to a recent human food exposure in parallel. Therefore, concentrations of a large set of brominated flame retardants (BFRs) (n = 27) including PBDEs, HBCDDs, TBBPA and novel flame retardants (nBFRs) have been determined in more than 600 food and feed samples collected between 2014 and 2016 in the context of French monitoring plans. Although legacy BFRs had already been studied in France, such a survey constituted the very first determination of nBFRs occurrence in foodstuffs at the national level. The concentration levels measured in fish and fish products were in general higher than in the other food categories. PBDEs were detected in 70% of the samples and were observed as the most abundant congeners (representing 80% of the sum of the monitored BFRs), while α-HBCDD could also be considered as a predominant congener (up to 26% of the sum of the monitored BFRs in fishes). nBFRs concentration levels were most of the time below the LOQ, except PBT, PBBz and HBBz which were more frequently detected at low levels. Also investigated in the study, BRPs exhibited high concentration levels in crustaceous (maximum value > 2700 pg/g ww).

Androgenic potential of human fetal adrenals at the end of the first trimester

The onset of steroidogenesis in human fetal adrenal glands (HFA) during the first trimester is poorly investigated. An unresolved question is the capacity of the HFA to produce potent androgen DHT via conventional and/or the backdoor pathway(s) at the end of first trimester, when androgen-responsive organs are developed. Our aim was to explore steroidogenesis and the expression of steroidogenic enzymes and transcription factors in HFA at gestational weeks (GW) 9-12 with focus on their androgenic potential. Steroids in the HFA were analyzed by gas chromatography/mass spectrometry. The expression of steroidogenic enzymes and transcription factors in the HFA at GW9-12 was investigated by qPCR, automated Western blotting and immunohistochemistry. We demonstrated that during GW9-12 HFA produced steroids of the ∆⁵, ∆⁴ and the backdoor pathways of the biosynthesis of DHT, though the latter was limited to production of 17α-OH-dihydroprogesterone, androsterone and androstanedione without further conversion to DHT. The only androgens identified in the HFA were testosterone and androsterone, a precursor in the biosynthesis of DHT. We also observed higher levels of CYP17A1 but low expression of 3βHSD2 at GW11-12 in the HFA. Elevated levels of CYP17A1 were associated with an increased expression of SF-1 and GATA-6. Altogether, our data demonstrate that of those steroids analyzed, the only potent androgen directly produced by the HFA at GW9-12 was testosterone. The onset of steroidogenesis in the HFA is a complex process that is regulated by the coordinated action of related transcription factors.

Country-specific chemical signatures of persistent organic pollutants (POPs) in breast milk of French, Danish and Finnish women

The present study compares concentrations and chemical profiles of an extended range of persistent organic pollutants (dioxins, polychlorobiphenyls, brominated flame retardants and organochlorine pesticides) in breast milk samples from French (n = 96), Danish (n = 438) and Finnish (n = 22) women. Median exposure levels observed in French women (WHO-TEQ₂₀₀₅ PCDD/F = 6.1 pg/g l.w., WHO-TEQ₂₀₀₅ dl-PCB = 4.3 pg/g l.w., sum of 6 ndl-PCB = 85.2 ng/g l.w., sum of 7 i-PBDE = 1.5 ng/g l.w.) appeared overall lower than in Danish and Finnish women for all examined POPs, except for α-HBCD (2-fold higher level at 0.6 ng/g l.w.). Furthermore, the observed exposure levels of dioxins and PCBs were higher in Danish women (WHO-TEQ₂₀₀₅ PCDD/F = 13.2 pg/g l.w., WHO-TEQ₂₀₀₅ dl-PCB = 6.6 pg/g l.w., sum of 6 ndl-PCB = 162.8 ng/g l.w.) compared to Finnish women (WHO-TEQ₂₀₀₅ PCDD/F = 9.0 pg/g l.w., WHO-TEQ₂₀₀₅ dl-PCB = 4.6 pg/g l.w., sum of 6 ndl-PCB = 104.0 ng/g l.w.), whereas the concentrations of PBDEs were similar for Danish and Finnish women (sum of 7 i-PBDE = 4.9 and 5.2 ng/g l.w. respectively). The organochlorine (OC) pesticide contamination profile, determined in a subset of French samples, was dominated by p,p'-DDE (56.6%), followed by β-HCH (14.2%), HCB (9.7%) and dieldrin (5.2%), while other compounds were only minor contributors (<5%). The three countries appeared to be discriminated by the observed contamination patterns of the PCDD/F versus PCB, and the 1,2,3,6,7,8-HxCDD versus 1,2,3,4,7,8-HxCDD ratios, in addition to the relative contributions of specific congeners to the contamination profile (PCBs #118 and #156, PBDEs #28, #47, #99 and #153). In conclusion, unique chemical signatures were observed for each country on the basis of some POP congeners. Future biomonitoring studies will need to consider the high variability of individual exposure profiles in relation to multiple exposure sources but also physiological and metabolic differences.

Thyroid endocrine status of wild European eels (Anguilla anguilla) in the Loire (France). Relationships with organic contaminant body burdens

In teleost fish, thyroid function is involved in various critical physiological processes. Given the complexity of the hypothalamo-pituitary-thyroid (HPT) axis, a large number of genes and proteins can be the potential target of endocrine-disrupting compounds (EDCs). The aim of this study was to evaluate, in yellow and silver European eels (Anguilla anguilla), potential effects of EDCs on thyroid status by analyzing the associations between EDC body burdens and thyroid hormones (THs). In yellow individuals, greater free T3/T4 ratios (FT3/FT4) and lower plasma FT4 levels were associated with greater concentrations of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs), as highlighted by significant correlations with many congeners. Few positive relationships with alkylphenols were noticed. In contrast, silver eels usually exhibited less significant correlations between THs and contaminant loads. Expression of a series of genes involved in the HPT axis was also investigated in the silver individuals. Concerning mRNA expression in silver females, some main correlations were noticed: thyroid-stimulating hormone (TSHβ) gene expression was significantly correlated to numerous PCBs, and hepatic mRNA levels of deiodinase 2 (Deio 2) were negatively correlated to 2-hydroxyfluorene (2-OHF) and 2-naphtol (2-OHNa). Thyroid receptor (TRα and TRβ) mRNA levels exhibited weak negative correlations with some PBDEs in silver females and males. Hepatic vitellogenin (Vtg) mRNA levels were detected in all silver males but at lower levels than in silver females. In males, Vtg mRNA levels were positively associated to FT4/TT4. In silver females, strong positive correlations were found between congeners of PCBs, PBDEs and PFAS suggesting potential estrogenic effects. Overall, the observed results indicate that several organic contaminants, mainly dl-, ndl-PCBs and PBDEs, could be associated with changes in thyroid homeostasis in these fish, via direct or indirect interactions with peripheral deiodination, metabolism of T4 and mechanisms involved in TSHβ, Deio 2 and Vtg gene transcription.

Occurrence of POPs and other persistent organic contaminants in the European eel (Anguilla anguilla) from the Loire estuary, France

The chemical contamination of the Loire estuary by three classes of persistent organic pollutants (POPs): the polychlorinated biphenyls (PCBs), the polybrominated diphenyl ethers (PBDEs) and the perfluorinated and polyfluorinated alkyl substances (PFAS), and three families of organic contaminants, the alkylphenols (APs), the polycyclic aromatic hydrocarbon metabolites (OH-PAHs) and the bisphenol A (BPA) were investigated in the muscles and bile of European eel (Anguilla anguilla). Yellow eels (n=30) were caught in three different points along the estuary to highlight variations between sites and sources of contaminations. Silver eels (n=15) were also studied to compare contaminant impregnation between different life stages of the species. Average concentrations in the muscles of the eel ranged between: 857 and 4358 ng/gLW for the PCBs, 26 and 46 ng/gLW for the PBDEs, 130 and 1293 ng/gLW for the PFAS; and in bile: 31 and 286 μg/g protein for the APs, 9 and 26 μg/g protein for the OH-PAHs and ND-1213 μg/g protein for the BPA. Among PCBs, PCB 153 (40% contribution to the sum of PCBs) was predominant in all eel muscles. PBDE 47 (60%) was the most predominant PBDE congeners, while perfluorooctanesulfonic acid (85%) was the most widely detected PFAS. For APs, 4p-nonylphenol (91%) was the most abundant and for the OH-PAHs, it was 1OH-Pyrene (63%). All the eels exceeded the environmental quality standards (EQS) for biota for the PBDEs and about 75% were higher than the EQS specific to PFOS. Finally, 20% of the analyzed eels presented TEQ concentrations above the maximum limits for lipid-rich species. These results supplied new data on the occurrence, levels, and patterns of 53 organic chemicals in the eels from the Loire estuary and they highlighted the need of further investigations focused notably on the potential effects of these chemicals on this species and their analysis in the water and sediments of the estuary.

Dietary exposure to perfluoroalkyl acids of specific French adult sub-populations: high seafood consumers, high freshwater fish consumers and pregnant women

Perfluoroalkyl acids (PFAAs) are globally found in various media, including food and especially fishery products. In the present study, the dietary exposure to 15 perfluoroalkyl acids was assessed for 3 French adult populations, namely high seafood consumers, high freshwater fish consumers, and pregnant women. Purified food extracts were analysed by LC-MS/MS and PFBA, PFPA, PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFTrDA, PFTeDA, PFBS, PFHxS, PFHpS, PFOS and PFDS were monitored and quantified according to the isotope dilution principle. Under lower bound (LB) hypothesis (i.e. contamination values<LOD considered as 0), high freshwater fish consumers appear as the most exposed to PFOS (7.5 ng.kg(-1) bw.d(-1)), PFUnA (1.3 ng.kg(-1) bw.d(-1)), PFDA (0.4 ng.kg(-1) bw.d(-1)) and PFHpS (0.03 ng.kg(-1) bw.d(-1)) while high seafood consumers appear as the most exposed to PFOA (1.2 ng.kg(-1) bw.d(-1)), PFNA (0.2 ng.kg(-1) bw.d(-1)) and PFHxS (0.06 ng.kg(-1) bw.d(-1)). For all considered populations, the major exposure contributors are fish, seafood and water under LB hypothesis, while dairy products, bread and crispbread are the main contributors under upper bound (UB) hypothesis. Besides this food exposure assessment, further studies are needed to assess the more global PFAA exposure, taking into account indoor and outdoor air, dust and cutaneous contact, which could be other important contributors for this particular class of chemicals.

Food risk assessment for perfluoroalkyl acids and brominated flame retardants in the French population: results from the second French total diet study

To determine the exposure of the French population to toxic compounds contaminating the food chain, a total diet study was performed in France between 2007 and 2009. This study was designed to reflect the consumption habits of the French population and covered the most important foods in terms of consumption, selected nutrients and contribution to contamination. Based on French consumption data, the present study reports the dietary exposure to perfluoroalkyl acids (16 congeners) and brominated flame retardants (polybrominated diphenyl ethers, hexabromocyclododecane and polybrominated biphenyls). Comparison of the calculated dietary exposures with the generally accepted health-based guidance values revealed that most compounds do not pose any risk. There are however knowledge gaps for some congeners in these large chemical classes.

Dioxin-like, non-dioxin like PCB and PCDD/F contamination in European eel (Anguilla anguilla) from the Loire estuarine continuum: spatial and biological variabilities

To characterize the eel contamination by dioxin-like (dl) and non dioxin-like (ndl) polychlorinated biphenyls (PCBs) and polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), sixty-two eels from the Loire estuary (France) were analyzed. PCB contamination significantly increased from glass eel stage (3.71 ± 1.85 and 15.2 ± 4.2 ng g(-1) dw) to other life stages (for yellow eels: 62.8 ± 34.4 and 382 ± 182 ng g(-1) dw; for silver eels: 93.7 ± 56.3 and 463 ± 245 ng g(-1) dw respectively for dl and ndl-PCBs). An inter-site variability based on PCB levels and profiles was observed among the three studied sites. For glass eels, the profile was mainly characterized by less chlorinated PCBs contrary to the other eels, displaying a different bioaccumulation pathway. Overall, the contamination level in the eels from this estuary was shown to be low for PCDD/Fs and intermediate for dl and ndl-PCBs, compared to other international/national areas. However, more than 60% of the studied silver eels displayed higher values for PCDD/F and dl-PCB WHO2005 TEQ than the EU permissible level of 10 pg g(-1) ww. This statement suggests a potential exposure to PCBs through eel consumption, especially with silver eels, and also points out apparent contamination that could eventually affect the reproductive success of the species.

Monitoring the endogenous steroid profile disruption in urine and blood upon nandrolone administration: An efficient and innovative strategy to screen for nandrolone abuse in entire male horses

Nandrolone (17β-hydroxy-4-estren-3-one) is amongst the most misused endogenous steroid hormones in entire male horses. The detection of such a substance is challenging with regard to its endogenous presence. The current international threshold level for nandrolone misuse is based on the urinary concentration ratio of 5α-estrane-3β,17α-diol (EAD) to 5(10)-estrene-3β,17α-diol (EED). This ratio, however, can be influenced by a number of factors due to existing intra- and inter-variability standing, respectively, for the variation occurring in endogenous steroids concentration levels in a single subject and the variation in those same concentration levels observed between different subjects. Targeting an efficient detection of nandrolone misuse in entire male horses, an analytical strategy was set up in order to profile a group of endogenous steroids in nandrolone-treated and non-treated equines. Experiment plasma and urine samples were steadily collected over more than three months from a stallion administered with nandrolone laurate (1 mg/kg). Control plasma and urine samples were collected monthly from seven non-treated stallions over a one-year period. A large panel of steroids of interest (n = 23) were extracted from equine urine and plasma samples using a C18 cartridge. Following a methanolysis step, liquid-liquid and solid-phase extractions purifications were performed before derivatization and analysis on gas chromatography-tandem mass spectrometry (GC-MS/MS) for quantification. Statistical processing of the collected data permitted to establish statistical models capable of discriminating control samples from those collected during the three months following administration. Furthermore, these statistical models succeeded in predicting the compliance status of additional samples collected from racing horses.

Production of polyclonal antibodies directed to recombinant methionyl bovine somatotropin

The administration of recombinant methionyl bovine somatotropin (rMbST) to dairy cows to increase milk yield remains a common practice in many countries including the USA, Brazil, Mexico, South Africa and Korea, whereas it has been forbidden within the European Union (EU) since 1999. A rapid screening immunoanalytical method capable of the unequivocal determination of rMbST in milk would be highly desirable in order to effectively monitor compliance with the EU-wide ban for home-made or imported dairy products. For decades, the production of specific antibodies for this recombinant isoform of bovine somatotropin (bST) has remained elusive, due to the high degree of sequence homology between both counterparts (e.g. methionine for rMbST in substitution of alanine in bST at the N-terminus). In this study, we compared several immunizing strategies for the production of specific polyclonal antibodies (pAbs), based on the use of the full-length recombinant protein, an rMbST N-terminus peptide fragment and a multiple antigen peptide (MAP) which consists of an oligomeric branching lysine core attached to the first two N-terminus amino acids of rMbST, methionine and phenylalanine (MF-MAP). The immunization with KLH-conjugated MF-MAP led to the production of the pAb with the highest rMbST/bST recognition ratio amongst the generated battery of antibodies. The pAb exhibited a specific binding ability to rMbST in a competitive antigen-coated ELISA format, which avidity was further improved after purification by rMbST N-terminus peptide-based affinity chromatography. These results suggest that immunodiscrimination between structurally related proteins can be achieved using immuno-enhanced immunogens such as MAPs.

Improvement of estradiol esters monitoring in bovine hair by dansylation and liquid chromatography/tandem mass spectrometry analysis in multiple reaction monitoring and precursor ion scan modes

RATIONALE

The control of forbidden anabolic practices in cattle in the European Union has become challenging since endogenous compounds such as estradiol derivatives can potentially be used as growth promoters. Due to the great difficulty in establishing a reference threshold value for endogenous steroids, the direct detection of steroid esters in hair is an efficient strategy for the detection of 'natural' steroid abuse in cattle.

METHODS

The present study aimed to develop and validate according to the current European standards a specific liquid chromatography/tandem mass spectrometry (LC/MS/MS) analytical strategy to monitor estrogen esters in bovine hair. The analysis was performed by positive ion electrospray ionisation (ESI+) after dansylation. Two acquisition modes were then assessed: single reaction monitoring and precursor ion scanning.

RESULTS

The results showed that the introduction of a dansylation step strongly improves the sensitivity of the detection of estradiol-17-esters by LC/(ESI+)-MS/MS. The CCα values are in the range 1-10 ng g(-1) after optimisation, except for estradiol decanoate for which the derivatisation is not efficient. In addition, this LC/MS/MS approach makes it possible to carry out a precursor ion scan to screen for the presence of these estradiol 17-esters in hair samples.

CONCLUSIONS

Based on the specific product ions, i.e. m/z 255 in native conditions or m/z 171 after dansylation, this strategy has the advantage of detecting any (un)known estradiol ester and of giving access to the [M + H](+) ion of the suspected ester through only a single analysis.

Thyreostatic drugs, stability in bovine and porcine urine

Thyreostatic drugs, illegally administrated to livestock for fattening purposes, are banned in the European Union since 1981. For monitoring their illegal use, sensitive and specific analytical methods are required. In this context, the knowledge of the stability in a matrix is of primary importance. This study aimed at evaluating the effects of preservation, number of freeze-thaw cycles, and matrix-related variables on the stability of thyreostatic drugs in the urine of livestock. Finally, the developed conservation approach was applied on incurred urine samples, which displayed traces of the thyreostat thiouracil below the recommended concentration of 10 μg L(-1). The stability study confirmed the negative influence of preservation (8 h) at room temperature and at -70 °C, decreases in concentration of more than 78.0% were observed for all thyreostats, except for 1-methyl-2-mercaptoimidazole and 2-mercaptobenzimidazole. Additionally, investigation of matrix-related variables indicated significant impacts of the presence of copper (p = 0.001) and the pH (p = 0.002). Next, an optimised pre-treatment (pH 1 and 0.1 M ethylenediaminetetraacetic acid disodium salt dehydrate) significantly differing from the original conservation approach (p < 0.05) was developed, which proved capable of delaying the decrease in concentration and improved the detection in time for both spiked as well as incurred urine samples. In the future, it seems highly advisable to apply the developed pre-treatment on incurred urines upon sampling, before thyreostat analysis. Additionally, it is recommendable to limit preservation of urine samples at room temperature, but also in the freezer prior to thyreostat analysis.

Presence and metabolism of endogenous androgenic-anabolic steroid hormones in meat-producing animals: a review

The presence and metabolism of endogenous steroid hormones in meat-producing animals has been the subject of much research over the past 40 years. While significant data are available, no comprehensive review has yet been performed. Species considered in this review are bovine, porcine, ovine, equine, caprine and cervine, while steroid hormones include the androgenic-anabolic steroids testosterone, nandrolone and boldenone, as well as their precursors and metabolites. Information on endogenous steroid hormone concentrations is primarily useful in two ways: (1) in relation to pathological versus 'normal' physiology and (2) in relation to the detection of the illegal abuse of these hormones in residue surveillance programmes. Since the major focus of this review is on the detection of steroids abuse in animal production, the information gathered to date is used to guide future research. A major deficiency in much of the existing published literature is the lack of standardization and formal validation of experimental approach. Key articles are cited that highlight the huge variation in reported steroid concentrations that can result when samples are analysed by different laboratories under different conditions. These deficiencies are in most cases so fundamental that it is difficult to make reliable comparisons between data sets and hence it is currently impossible to recommend definitive detection strategies. Standardization of the experimental approach would need to involve common experimental protocols and collaboratively validated analytical methods. In particular, standardization would need to cover everything from the demographic of the animal population studied, the method of sample collection and storage (especially the need to sample live versus slaughter sampling since the two methods of surveillance have very different requirements, particularly temporally), sample preparation technique (including mode of extraction, hydrolysis and derivatization), the end-point analytical detection technique, validation protocols, and the statistical methods applied to the resulting data. Although efforts are already underway (at HFL and LABERCA) to produce more definitive data and promote communication among the scientific community on this issue, the convening of a formal European Union working party is recommended.

Analysis of thyreostats: a history of 35 years

Thyreostatic drugs (TS), illegally administrated to livestock for fattening purposes, are banned in the European Union since 1981 (Council Directive 81/602/EC). This paper reviews the trends in the analytical approaches for the determination of TS drugs in biological matrices. After a brief introduction on the different groups of compounds with a thyreostatic action, the most relevant legislation regarding the residue control of these compounds is presented. An overview of the analytical possibilities for the determination of TS in animal matrices, covering sample extraction, purification, separation techniques and detection methods is provided. Additionally, a brief outline of animal experiments is described that illustrates the excretion and distribution profiles of TS residues. Finally, the novel developments in TS analysis are highlighted. Also the possible semi-endogenous status of thiouracil is discussed.

Determination of naturally occurring oestrogens and androgens in retail samples of milk and eggs

The occurrence of the main steroid hormones (oestrone, 17alpha-oestradiol, 17beta-oestradiol, 17alpha-testosterone, 17beta-testosterone, dehydroepiandrosterone, 4-androstenedione), especially in milk and eggs, was investigated. An analytical method based on GC-MS/MS was developed for steroid measurement at an ultra-trace level in food products. The limits of detection for oestrogens were about 5 and 30 ng kg(-1) in milk and eggs, respectively. For androgens, the limits of detection were around 10 and 50 ng kg(-1) in milk and eggs, respectively. The method was applied to milk and egg samples collected in a French supermarket. In milk, oestrone was found at levels between 100 and 300 ng l(-1), while 17beta-oestradiol levels were estimated to be near 20 ng l(-1). 17alpha-testosterone was found to be from 50 ng l(-1) in skimmed milk to 85 ng l(-1) in whole milk. In egg samples, oestrone and 17beta-oestradiol were found at 1.5 and 0.9 microg kg(-1), respectively, while 17alpha-oestradiol was found to be in lower concentrations (i.e. around 0.55 microg kg(-1)). Regarding androgens, 17alpha- and 17beta-testosterone were estimated at 1.9 and 1.3 microg kg(-1), respectively. These results represent a first attempt to estimate the food exposure to steroid hormones. In the future, the collection of additional data should permit the comparison between this exogenous dietary intake and the daily endogenous production in pre-pubertal children as a basis of risk assessment regarding endocrine disruption linked to these molecules for this critical population.

Evidence that urinary excretion of thiouracil in adult bovine submitted to a cruciferous diet can give erroneous indications of the possible illegal use of thyrostats in meat production

Thyrostats have been banned for use as veterinary drugs in Europe since 1981 because of their carcinogenic and teratogenic properties. Until now, the identification of thiouracil in animal biological matrices has been interpreted as the consequence of an illegal administration. The present paper studies the influence of a cruciferous-based feed on the occurrence of thiouracil as a residue in urine. Urine samples collected from two heifers fed on cabbage or rapeseed cakes were analysed for the presence of thiouracil by 3-iodobenzylbromide derivatization and liquid chromatography-electrospray ionization tandem mass spectroscopy (LC-ESI(-)-MS/MS) analysis. Urine collected after cabbage or rapeseed feeding showed thiouracil concentrations in the range 3-7 and 2-9 microg l-1, respectively, demonstrating a relationship between a diet based on cruciferous vegetables and the occurrence of thiouracil in urine. Thiouracil was excreted in urine in the hours following cruciferous intake. Complete elimination (<0.8 microg l-1) of the compound occurred within 5 days. The precursors in cruciferous vegetables responsible for the thiouracil excretion in urine were proved not to be thiouracil itself.

Past, present and future of mass spectrometry in the analysis of residues of banned substances in meat-producing animals

A residue is a trace (microg kg(-1), ng kg(-1)) of a substance, present in a matrix. Banned substances, such as growth promoters, which are abused in animal fattening and where this article is focused on, may be divided into four major groups: thyreostats, anabolics or anabolic steroids, corticosteroids and beta-agonists or repartitioning agents. The combination of chromatographic techniques with mass spectrometry (GC-MS(n), LC-MS(n), etc.) plays a key role in the production of specific results in residue analysis. In this review, the past, present and future of mass spectrometry in this area are discussed in the light of the impact of these substances on human health and the reliable production of analytical results, ready for challenge in a court.

Milk and Urine Excretion of Polycyclic Aromatic Hydrocarbons and Their Hydroxylated Metabolites After a Single Oral Administration in Ruminants

The aim of this study was to establish the transfer of phenanthrene, pyrene, and benzo[a]pyrene and their major hydroxylated metabolites to milk and to urine after a single oral administration (100 mg per animal of each compound) in 4 lactating goats. Detection and identification of the analytes (native compounds, 1-OH pyrene, 3-OH phenanthrene, 3-OH benzo[a]pyrene) were achieved using gas chromatography-mass spectrometry. Benzo[a]pyrene, phenanthrene, and pyrene were rapidly detected in the plasma stream, whereas 1-OH pyrene and 3-OH phenanthrene appeared later in plasma. These data suggest that pyrene and phenanthrene are progressively metabolized within the organism. Recovery rates of pyrene and phenanthrene in milk over a 24-h period appeared to be very low (0.014 and 0.006%, respectively), whereas the transfer rates of their corresponding metabolites were significantly higher: 0.44% for 1-OH pyrene and 0.073% for 3-OH phenanthrene. Recovery rates in urine were found to be higher (1 to 10 times) than recovery rates in milk. The 1-OH pyrene was found to be the main metabolite in urine as well as in milk. Thus, as has been established for humans, 1-OH pyrene could be considered as a marker of ruminant exposure to polycyclic aromatic hydrocarbons. Because 1-OH pyrene and 3-OH phenanthrene were measured in milk (unlike their corresponding native molecules), metabolites of polycyclic aromatic hydrocarbons should be taken into consideration when evaluating the safety of milk. Benzo[a]pyrene and 3-OH benzo[a]pyrene were (less than 0.005%) transferred to milk and urine in very slight amounts. This very limited transfer rate of both compounds suggests a low risk of exposure by humans to benzo[a]pyrene or its major metabolite from milk or milk products.

Urinary excretion of 5(10)-estrene-3beta,17alpha-diol and estrone by the female horse: complementary indicators of early pregnancy screened with regard to a putative anabolic doping practice

Rules of horse racing stipulate that pregnant mares may compete under definite conditions of date, because early pregnant status may be misused for the sake of enhancing physical performance by putative anabolic steroid action. Screening for pregnancy is generally performed by plasma equine gonadotrophin (eCG) immunoassay, which covers the period between Days 40 and 120. In common screening for urinary anabolic steroids performed by gas chromatography-mass spectrometry, inclusion of two complementary criteria, i.e. the evaluation of total conjugates of 5(10)-estrene-3beta,17alpha-diol (EED) and estrone (E1), can easily be performed. Although EED and E1 have no anabolic property per se in the horse, assessing these two markers may be helpful in the period comprised between Days 70 and 250, thereby prolonging the detection period behind that of eCG. Peak values of EED and E1 are then attained, so that visual inspection of chromatographic tracings remains in general sufficient as a diagnostic tool. Comparison of EED and E1 during pregnancy and in an estrus cycle indicates a drastic difference in the attained excretion values, attributable to either the placenta or the ovarian follicle. The identity of EED has been proven by GC-MS(n) in urine and in placental tissue.

Mass spectrometric detection of and similarities between 1-androgens

Regularly new anabolic steroids appear on the black market. In most cases these substances are marketed on websites or are confiscated during inspections. 1,(5alpha)-Androstene-17beta-ol-3-one, also known as 1-testosterone, is one of these substances presented to body-builders as a nutritional supplement or a pro-hormone. 1-Testosterone closely resembles the natural hormone testosterone except for a 1,2-double bound instead of a 4,5-double bound. 1-Androstene-3beta,17beta-diol is transformed into 1-testosterone after oral administration. 1-Testosterone, 1-androstene-3beta,17beta-diol and some other related 'new' anabolic steroids were studied with gas chromatography coupled to mass spectrometry (GC-MS) and Liquid chromatography coupled to tandem mass spectrometry (LC-MS2) methods. Similarities in spectra to known analytes, which may lead to pitfalls in the interpretation of the derivatised analytes, are discussed.

Phytosterols and anabolic agents versus designer drugs

Cholesterol is a well-known component in fats of animal origin and it also is the precursor of natural hormones. Phytosterols appear in plants and only differ slightly in structure from cholesterol. An important difference however is the low absorption in the gut of phytosterols and their saturated derivatives, the phytostanols. As a result, there is time for all kind of reactions in faecal material inside and outside of the gut. Determination of the abuse of natural hormones may be based on gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Abuse of natural hormones changes the 13C/12C ratio of some metabolites during a relatively long time. The formation of (natural) hormones in the gut may interfere with this method. Designer drugs are mainly known from sports doping. In animal fattening, designer drugs may be used as well. Small changes in the structure of (natural) hormones may lead to a new group of substances asking for new strategies for their detection and the constatation of their abuse.

Development and application of stable carbon isotope analysis to the detection of cortisol administration in cattle

The use of anabolic agents in food-producing animals has been prohibited within the EU since 1988. The control of the illegal use of natural steroid hormones in cattle is still an exciting analytical challenge as no definitive method and nonambiguous analytical criteria are available. We have used gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to demonstrate the administration of cortisol to cattle. The method consisted of an efficient combination between OASIS HLB solid-phase extraction (SPE), oxidation, SiOH SPE and semi-preparative high-performance liquid chromatography (HPLC) for glucocorticoid purification. By comparison of the (13)C/(12)C isotopic ratio of the oxidised product of cortisol, i.e. 5 beta-androstane-3,11,17-trione (5 beta AAT), with an endogenous reference compound (ERC), dehydroepiandrosterone (DHEA), the differentiation of cortisol metabolite origin, either endogenous or exogenous, has been achieved. After treatment of an animal, the delta(13)C(VPDB) values of 5 beta AAT reached -30 to -32 per thousand, whereas the delta(13)C(VPDB) values of DHEA remained at -25 per thousand. A significant difference in the delta(13)C(VPDB) values between DHEA and 5 beta AAT was measurable over a period of 3 days after a single administration of cortisol to the animal.

LC–ESI-MS/MS determination of phenylurea and triazine herbicides and their dealkylated degradation products in oysters

A method was developed for the determination of several phenylurea and triazine herbicides and their transformation products in oysters at the low microg/kg level. Pressurised liquid extraction (PLE) of lyophilisated samples had required successive SPE combined with a liquid/liquid extraction to provide relatively clean extracts for the determination in LC-MS/MS. This procedure was validated according to the 2002/657/EC analytical decision. Efficiency of the analytical method led to confirmatory CCalpha values ranging from 0.1 to 14 microg/kg with an R.S.D. value ranging from 14% to 66% and a recovery yield ranging from 32% to 46% for phenylureas and from 29% to 75% for triazines.

New anabolic steroid illegally used in cattle-structure elucidation of 19-norchlorotestosterone acetate metabolites in bovine urine

4-Chloro-estr-4-en-17-ol-3-one, trivially named 19-norclostebol acetate or 4-chloro-19-nortestosterone acetate (NClTA), has been identified on the European black market in the late 1990s for possible use in breeding animals. After oral and subcutaneous administration of NClTA to bovine, urine samples were collected over a period of three weeks, and chemical structure of main excreted urinary metabolites was determined. After oral administration, the most abundant metabolites were mainly reduced as 4-chloro-19-norandrostan-3xi-ol-17-one and 4-chloro-19-norandrostan-3xi,17xi-diol. They were identified until 1 week after administration. Following subcutaneous injection, 4-chloro-19-norandrostan-3xi-ol-17-one was again of major abundance, but so were 4-chloro-19-norandrost-4-ene-3xi,17xi-diol and 4-chloro-19-norandrost-4-en-3xi-ol-17-one. They were detected at least 3 weeks after administration. Whatever the route of administration, metabolites were found mainly glucurono-conjugated; the only exception was metabolite 4-chloro-19-norandrostan-3xi-ol-17-one which was identified both in the sulpho- and glucurono-fractions.

Application of stable carbon isotope analysis to the detection of 17β-estradiol administration to cattle

The use of anabolic agents in food producing animals is prohibited within the EU since 1988 (96/22/EC directive). The control of the illegal use of natural steroid hormones in cattle is still an exciting analytical challenge as far as no definitive method and non-ambiguous analytical criteria are available. The ability of gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) to demonstrate the administration of 17beta-estradiol to bovine has been investigated in this paper. By comparison of 13C/12C isotopic ratio of main urinary estradiol metabolite, i.e. 17alpha-estradiol, with two endogenous reference compounds (ERCs), i.e. dehydroepiandrosterone (DHEA) and 5-androstene-3beta,17alpha-diol, the differentiation of estradiol metabolite origin, either endogenous or exogenous, has been proved to be achievable. After treatment, the delta(13)C(VPDB)-values of 17alpha-estradiol reached -27 per thousand to -29 per thousand, whereas delta13CVPDB-values of DHEA remained between -13 per thousand and -20 per thousand depending on the diet, maize and grass, respectively. A significant difference of delta13CVPDB between ERCs and 17alpha-estradiol was measurable over a period of 2 weeks after estradiol ester administration to the animal.

Endogenous occurrence of some anabolic steroids in swine matrices

Following findings of 17beta-19-nortestosterone (150-200 microg kg(-1)) in pigs of unspecified gender imported into the European Union, a study to determine steroid and hormone levels in swine from six age/gender categories (uncastrated 'old' boars, cryptorchids, one intersex, barrows, gilts and sows) was initiated. Indeed, for some hormones there has been a discussion about their being endo- or exogenous. Tissue and urine samples from swine from each of the six categories were obtained in Belgium, France, the Netherlands and the USA. Samples were analysed in three laboratories. Quantitation was obtained for norandrostenedione, 19-nortestosterone and boldenone. The results give a well-documented overview of the status of the presence of these hormones in swine. The data illustrate that uncastrated 'old' boars produce the highest percentage of 'positive' matrices, followed by the cryptorchids. Concentrations in the matrices of the barrows and the gilts are lower. Also, sow matrices contain low amounts of nor-steroids. Furthermore, urine samples from an intersex pig contains a higher concentration of nortestosterone than sows and can therefore be suspected for illegal use of these hormones. Veterinarians taking samples in pig farms for the analysis of hormones need to be aware of the presence and concentrations of these substances in the different categories.

Presence and metabolism of the anabolic steroid boldenone in various animal species: a review

The review summarizes current knowledge on the possible illegal use of the anabolic steroid boldenone. The presence of' boldenone and metabolites in different animal species and the possibility of the occurrence of endogenous boldenone and metabolites is assessed, as are the methods of analysis used for detection. Different laboratories in the European Union have examined the occurrence of boldenone and its metabolites. The results were discussed at different meetings of a European Commission DG-SANCO Working Party) and summarized in an expert report. The situation of the different laboratories at this time is also covered herein. The overall conclusion of the Working Party was that there was a necessity for further research to distinguish between naturally occurring and illegally used boldenone forms. The confirmation of the presence of boldenone metabolites (free and conjugated forms) in certain matrices of animals is proposed as a marker for the illegal treatment with boldenone.