Characterizing the scent and chemical composition of Panthera leo marking fluid using solid-phase microextraction and multidimensional gas chromatography–mass spectrometry-olfactometry

Lions (Panthera leo) use chemical signaling to indicate health, reproductive status, and territorial ownership. To date, no study has reported on both scent and composition of marking fluid (MF) from P. leo. The objectives of this study were to: 1) develop a novel method for simultaneous chemical and scent identification of lion MF in its totality (urine + MF), 2) identify characteristic odorants responsible for the overall scent of MF as perceived by human panelists, and 3) compare the existing library of known odorous compounds characterized as eliciting behaviors in animals in order to understand potential functionality in lion behavior. Solid-phase microextraction and simultaneous chemical-sensory analyses with multidimensional gas-chromatography-mass spectrometry-olfactometry improved separating, isolating, and identifying mixed (MF, urine) compounds versus solvent-based extraction and chemical analyses. 2,5-Dimethylpyrazine, 4-methylphenol, and 3-methylcyclopentanone were isolated and identified as the compounds responsible for the characteristic odor of lion MF. Twenty-eight volatile organic compounds (VOCs) emitted from MF were identified, adding a new list of compounds previously unidentified in lion urine. New chemicals were identified in nine compound groups: ketones, aldehydes, amines, alcohols, aromatics, sulfur-containing compounds, phenyls, phenols, and volatile fatty acids. Twenty-three VOCs are known semiochemicals that are implicated in attraction, reproduction, and alarm-signaling behaviors in other species

Determination of selenium in rat brain by synchrotron radiation X-ray fluorescence

Selenium, an ubiquitous essential trace-element, is known to be particularly difficult to measure especially in brain. First, it is a non metal, next, at very low concentration (below ppm); at last, the brain matter, very rich in lipids, make the digestion specially uneasy. Using synchrotron radiation induced X-ray fluorescence analysis (SXRF), selenium in rat brain was measured equal to ${\rm C_{Se}}$ = 124 $\pm$ 5.4 ppb with a MDL (minimum detection limit) of 20 ppb. The obtained values should be used as a first step to study human brain on extremely small and specific locations. With the development of aging pathologies (such as Alzheimer's or Parkinson's disease...), it matters to get informations about selenium known as an anti-aging element. The obtained values from rat, near of man's, may also highlight it as a potential animal model system for studying selenium in human brain

Beta-2 agonists and exercise performance in humans

Etat des connaissances concernant les effets ergogéniques des bêta-2 agonistes (terbutaline, bambutérol, salmétérol, formotérol). 'Si les études conduites suite à des inhalations de bêta-2 agonistes à dose thérapeutique ne mettent pas en évidence d'amélioration de la performance sportive (de faibles doses administrées n'entraînant pas de passage systémique significatif) la quasi-totalité des étude conduites après administration orale aiguë et de courte durée semble montrer une amélioration de la performance sportive, quelle que soit l'intensité de l'exercice effectué'