InnOscent system: Advancing flavor analysis using an original gas chromatographic analytical device.

Despite continuous advances in analytical and physiological knowledge, the comprehension of an aroma is still a challenge. Gas chromatography coupled to olfactometry (GC-O) is an efficient method to identify and estimate individual potential of odorants, but there is a gap between this individual characterization and the effective contribution of compounds in the mixture, which is due to complex chemical and perceptual interactions. Therefore, recombination and omission experiments are often performed to achieve an understanding of food aromas. In this study, a chromatographic device, developed to facilitate aroma analysis, is presented. It was configured to perform both (1) conventional analyses by GC coupled with a mass spectrometer, olfactometric port(s), and a flame ionization detector (FID), and (2) omission or recombination experiments. This dual capability is due to the singular configuration of the system using an ingenious combination of splitter and Deans switch microfluidics transfer modules, and the existence of multiple outlets. The operational status of the system was tested using a purposely simple mixture of compounds. The similarity of retention times (RT) and FID peak areas obtained for each outlet demonstrates that the multiple outlets of the system are equivalent. The reproducibility of retention times (RT) and FID peak areas obtained in switching and non-switching conditions, also demonstrates the efficiency of switching operations. The validation of the system enables multiple detectors to be connected to the outlets and complementary information can be obtained from the eluate. The connection of recovery disposals to the outlets provides fraction collection and recombination possibilities, which contribute much to the understanding of aroma-aroma interactions. As an illustration of the InnOscent system relevance for the comprehension of more complex aromas, the device was used to study the aroma of a wine made from Cabernet Franc grape variety. An olfactometric profile was efficiently produced with the device configured as a GC-MS coupled to a dual olfactometric port. The main odorant active compounds were identified. The omission approach, carried out with the system on isopropyl- and isobutyl-methoxypyrazines, demonstrates the significant contribution of these compounds to the aroma of the wine studied, despite an individual perception among the weakest of the aromagram. A similar approach can be used to evaluate the contribution of any compound to any aroma. This approach overcomes constraints of current methodologies associated to reconstituted model solutions and paves the way for a better understanding of aroma construction.

[Efficacy of Spirolept vaccine against human leptospirosis as estimated by passive protection of laboratory rodents]. / Etude de l'efficacité du vaccin Spirolept contre la leptospirose par la protection passive de rongeurs de laboratoire.

OBJECTIVE: This study had for aim to assess the serological response induced by the Spirolept vaccine against human leptospirosis. METHOD: A serological follow-up was made on 31 patients at a risk of occupational exposure. The antibody titers of vaccinated patients were assessed by MAT and ELISA. In a second step, vaccinal protection was studied in vivo by checking the seroprotective effect of the human sera injected in an animal model (Meriones unguiculatus) naturally susceptible to the disease. The passive protection was studied by comparing the death rate on five batches of animals to which the bacterium was inoculated. Thus, four batches of animals were injected subcutaneously with a pooled sera of vaccinated people sampled at D0, D15, D135, and D320 after Spirolept vaccination. One control batch was given PBS. One day after injection, the latter batch was inoculated with the homologous strain Verdun of Leptospira interrogans ss icterohemorrhagiae (serogroup Icterohemorrhagiae) used to make the vaccine. RESULTS: The death rate was significantly decreased as soon as D15 after the first injection, even with pooled sera of vaccinated people negative for the MAT. COMMENTS: The Spirolept vaccine induces a protective response against icterohemorrhagiae, which can be transmitted to the animal model and thus is linked to a humoral response.

Role of the coypu (Myocastor coypus) in the epidemiology of leptospirosis in domestic animals and humans in France.

The coypu (Myocastor coypus), a rodent whose natural habitat is stagnant freshwater, has become a widespread pest in France within the last decade. This study investigated the prevalence of seropositivity and the renal carriage of leptospires in coypus in order to evaluate their role in terms of the risk of infection by Leptospira interrogans in domestic animals and humans. The study involved the application of serological and bacteriological methods to identify leptospires infection and/or carriage in 738 coypus trapped from 1996 to 1999 in six areas of France. Seroprevalence in samples ranged from 16.5 to 66%, and three field strains were isolated (two L. interrogans Icterohaemorrhagiae and one L. interrogans Sejroe). This first report on the isolation of leptospires from coypus in France emphasises the role of this animal in the epidemiology of leptospirosis.