Targeted phase II metabolites profiling as new screening strategy to investigate natural steroid abuse in animal breeding

The use of steroid hormones as growth promoters in cattle is banned within the European Union since 1988 but can still be fraudulently employed in animal breeding farms for anabolic purposes. While efficient targeted confirmatory methods have been implemented in control laboratories for many years, fast and reliable screening methods are still required, especially in the case of natural hormones abuse, but more globally for new "fishing" strategies allowing to reveal the use of even unknown anabolic agents. The development of focused profiling or untargeted metabolomic approaches is thus emerging in this context. The present study was a focused profiling study using steroids phase II metabolites, with the aim to get a better understanding of the steroid metabolism disruptions after exogenous administration of androstenedione and finally reveal potential biomarkers signing its administration. A sample preparation procedure was first developed, based on a separation of 31 glucuronide and sulphate conjugate compounds using an anion exchange SPE system. Each fraction was then analysed by UPLC-MS/MS in MRM mode showing a rapid (between 4h and 4 days after treatment) and huge excretion of several direct metabolites of androstenedione such as etiocholanolone-glucuronide or epiandrosterone-sulphate.     

Hetero-Diels–Alder reactions of perfluoroalkyl thioamides with electron-rich 1,3-dienes: synthesis of new 2-aminosubstituted-3,6-dihydro-2H-thiopyrans and related compounds

Hetero-Diels–Alder reactions of perfluoroalkyl thioamides with electron-rich 1,3-dienes such as 2,3-dimethylbutadiene, isoprene or penta-1,3-diene gave a simple and efficient access to new 2-aminosubstituted-3,6-dihydro-2H-thiopyrans. Three different procedures were used depending on the nature of the polyfluoroalkyl chains (R_F=CF₃, (CF₂)_nCF₃, (CF₂)₄H) and on the nitrogen substituents of the thioamides (R¹, R²=H, p-Tol, morpholino, Ac). Moreover, cycloadditions of silyloxydienes (1- or 2-trimethylsilyloxy-1,3-butadiene and Danishefsky's diene) with N-acyl,N-tolyl trifluoromethylthioamides afforded in almost all cases the corresponding 3,6-dihydro-2H-thiopyrans or 3-oxo-tetrahydrothiopyrans. For non-symmetrical 1,3-dienes, the regio- and stereochemistry of the reactions were studied (especially using X-ray diffraction analysis) indicating a strong similarity with those reported for fluorinated thiocarboxyl derivatives. Finally, two silylated 3,6-dihydro-2H-thiopyrans underwent an unexpected base-induced ring contraction to give new 1,3-thiazolidin-4-ones.     

A polyhedral study on 0–1 knapsack problems with disjoint cardinality constraints: Strong valid inequalities by sequence-independent lifting

We study the set of 0–1 integer solutions to a single knapsack constraint and a set of non-overlapping cardinality constraints (MCKP), which generalizes the classical 0–1 knapsack polytope and the 0–1 knapsack polytope with generalized upper bounds. We derive strong valid inequalities for the convex hull of its feasible solutions using sequence-independent lifting. For problems with a single cardinality constraint, we derive two-dimensional superadditive lifting functions and prove that they are maximal and non-dominated under some mild conditions. We then show that these functions can be used to build strong valid inequalities for problems with multiple disjoint cardinality constraints. Finally, we present preliminary computational results aimed at evaluating the strength of the cuts obtained from sequence-independent lifting with respect to those obtained from sequential lifting.     

Temperature and Inoculum Origin Influence the Performance of Ex-Situ Biological Hydrogen Methanation

The conversion of H₂ into methane can be carried out by microorganisms in a process so-called biomethanation. In ex-situ biomethanation H₂ and CO₂ gas are exogenous to the system. One of the main limitations of the biomethanation process is the low gas-liquid transfer rate and solubility of H₂ which are strongly influenced by the temperature. Hydrogenotrophic methanogens that are responsible for the biomethanation reaction are also very sensitive to temperature variations. The aim of this work was to evaluate the impact of temperature on batch biomethanation process in mixed culture. The performances of mesophilic and thermophilic inocula were assessed at 4 temperatures (24, 35, 55 and 65 °C). A negative impact of the low temperature (24 °C) was observed on microbial kinetics. Although methane production rate was higher at 55 and 65 °C (respectively 290 ± 55 and 309 ± 109 mL CH₄/L.day for the mesophilic inoculum) than at 24 and 35 °C (respectively 156 ± 41 and 253 ± 51 mL CH₄/L.day), the instability of the system substantially increased, likely because of a strong dominance of only Methanothermobacter species. Considering the maximal methane production rates and their stability all along the experiments, an optimal temperature range of 35 °C or 55 °C is recommended to operate ex-situ biomethanation process.     

A General Method for Computer-Assisted Proofs of Periodic Solutions in Delay Differential Problems

Journal of Dynamics and Differential Equations - In this paper we develop a general computer-assisted proof method for periodic solutions to delay differential equations. The class of problems...     

Harmonic Functions,Conjugate Harmonic Functions and the Hardy Space $$H^1$$ H 1 in the Rational Dunkl Setting

Journal of Fourier Analysis and Applications - In this work we extend the theory of the classical Hardy space $$H^1$$ to the rational Dunkl setting. Specifically, let $$\Delta $$ be the Dunkl...     

Sums of even powers in Archimedean rings

This note is devoted to the study of totally archimedean rings of regular functions. We extend Schmüdgen's theorem to this class of rings. Moreover, we show that, in such rings, every totally positive element is a sum of even powers of totally positive elements, and hence is a sum of even powers of units. Received: 21 October 1999; in final form: 10 November 2000 / Published online: 18 January 2002     

Effective monitoring for ractopamine residues in samples of animal origin by SPR biosensor and mass spectrometry

Ractopamine (RCT) is a member of the β-2-agonist (β-agonist) family. It is licensed for use as an animal growth promoter in more than 20 countries worldwide, including the United States and Canada, but is either not licensed or prohibited by over 150 others, including those within the European Union. The issue of the use of RCT in livestock bound for human consumption has risen to prominence recently following the decision by The People's Republic of China to ban the import of pork from a number of processing plants after finding traces of RCT in shipments from the U.S.A.In order to monitor for the illegal use of such compounds within Europe, there is a requirement to have a robust and reliable testing scheme capable of the detection of low concentrations of RCT. In the present study an optical biosensor screening assay was developed. The developed assay was compared with a liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS) confirmatory procedure. These methods were used to study the ability to detect RCT in pigs following treatment. Both testing procedures were capable of detecting low μg kg⁻¹ concentrations of the drug in urine and liver. Liver was found to be a less suitable sample matrix, with RCT residue levels being undetectable after 5 days withdrawal of the drug. Urine samples however still contained detectable RCT residues several weeks after withdrawal. The correlation (as measured by r²) between the biosensor and LC-MS/MS methods was 0.99 and 0.97 for urine and liver samples, respectively.It is concluded that testing regimes based on RCT analysis in liver are less likely to detect illegal administration of the drug than those based on urine analysis. Urine samples provide an excellent matrix for the detection of RCT residues for an extended period post withdrawal.