Determination of l-cysteine origin on the basis of its δ15N values.

The majority of l-cysteine is obtained industrially by hydrolysis of animal materials, such as poultry feathers. Despite widespread belief, there is little evidence that human hair is used as a source material and its use is explicitly banned in the European Union (2000/63/EC decision). We developed an isotope ratio mass spectrometric (EA-IRMS) method to determine carbon and nitrogen isotopic ratio in cysteine preparations and related compounds, e.g. cystine and carbocysteine. A threshold relying on the 15N/14N was established to differentiate between hair and feathers; a value below 6.6‰ indicates a poultry feathers origin. Global uncertainty of measurement was found to be 0.1‰ for δ15N (sample size of 0.5-1.8 mg).

5α-Estrane-3ß,17ß-diol and 5ß-estrane-3α,17ß-diol: definitive screening biomarkers to sign nandrolone abuse in cattle?

17ß-Nandrolone (17ß-NT) is one of the most frequently misused anabolic steroids in meat producing animals. As a result of its extensive metabolism combined with the possibility of interferences with other endogenous compounds, detection of its illegal use often turns out to be a difficult issue. In recent years, proving the illegal administration of 17ß-NT became even more challenging since the presence of endogenous presence of 17ß-NT or some of its metabolite in different species was demonstrated. In bovines, 17α-NT can occur naturally in the urine of pregnant cows and recent findings reported that both forms can be detected in injured animals. Because efficient control must both take into account metabolic patterns and associated kinetics of elimination, the purpose of the present study was to investigate further some estranediols (5α-estrane-3ß,17ß-diol (abb), 5ß-estrane-3α,17ß-diol (bab), 5α-estrane-3ß,17α-diol (aba), 5α-estrane-3α,17ß-diol (aab) and 5ß-estrane-3α,17α-diol (baa)) as particular metabolites of 17ß-NT on a large number of injured (n=65) or pregnant (n=40) bovines. Whereas the metabolites abb, bab, aba and baa have previously been detected in urine up to several days after 17ß-NT administration, the present study showed that some of the isomers abb (5α-estrane-3ß,17ß-diol) and bab (5ß-estrane-3α,17ß-diol) could not be detected in injured or pregnant animals, even at very low levels. This result may open a new way for the screening of anabolic steroid administration considering these 2 estranediols as biomarkers to indicate nandrolone abuse in cattle.