Search results for "Spectrométrie de masse"
showing 9 items of 9 documents
III. Biochemistry of S-layers
1997
During evolution prokaryotes have developed different envelope structures exterior to the cell wall proper. Among these surface components are regularly arranged S-layers and capsules. The structural characterization and the detailed chemical analysis of these surface molecules is a prerequisite to understand their biosynthesis and functional role(s) at the molecular level. Of particular interest are the glycosylated S-layer proteins which belong to the first prokaryotic glycoproteins ever described. Their characterization was performed on strains belonging to the thermophilic Bacillaceae and included structural studies and experiments to learn about the pathways for the glycan biosynthesis…
Oxidation-Induced Increase In Photoreactivity of Bovine Retinal Lipid Extract
2017
Open access original paper Source : 10th EPR Workshop on Applications of EPR in Biology and Medicine, 2016 in Krakow, POLAND.; International audience; The mammalian retina contains a high level of polyunsaturated fatty acids, including docosahexaenoic acid (22:6) (DHA), which are highly susceptible to oxidation. It has been shown that one of the products of DHA oxidation-carboxyethylpyrrole (CEP), generated in situ, causes modifications of retinal proteins and induces inflammation response in the outer retina. These contributing factors may play a role in the development of age-related macular degeneration (AMD). It is also possible that some of the lipid oxidation products are photoreactiv…
Noise identification and sampling frequency determination for precise Pb isotopic measurements by quadrupole-based Inductively Coupled Plasma Mass Sp…
2000
Analytical precision of the isotope ratios measured by quadrupole-based ICP-MS is drastically controlled by the low- frequency noises which originate from nebulisation and vaporisation processes, and from sample introduction systems. The unde- sirable influence of these latter can be however reduced by choosing efficiently the operating parameters. In the present study , the choice of the stabilisation time necessary in peak jump mode, and the one of the number of sweeps are discussed in the light of noise power spectra obtained with various speeds of the peristaltic pump used as sample introduction system. Obviously, the settings proposed are probably efficient only on our own ICP-MS, but …
Identification of volatile compounds of fruit juice by head space (HSSE) and immersion stir bar sorptive extraction (SBSE) and thermal desorption-cry…
2015
Identification of volatile compounds of fruit juice by head space (HSSE) and immersion stir bar sorptive extraction (SBSE) and thermal desorption-cryogenic focusing-gas chromatography mass spectrometry. 16. International Symposium on Olfaction and Electronic Noses (ISOEN 2015)
Organoleptic propoerties of dark chocolates investigated by direct-injection mass spectrometry (PTR-To-MS) and GC-olfactometry
2017
15. Weurman Flavour Research Symposium ; Graz (Autriche) - (2017-09-18 - 2017-09-22); International audience; A preliminary sensory study conducted on a set of 187 dark chocolates varying in terms of cocoa origin and variety allowed their classification into four distinct sensory categories. Fingerprints in volatile organic compounds (VOCs) of these chocolates wereobtained by a direct-injection mass spectrometry headspace method using Proton Transfer Reaction Mass Spectrometry (PTR-MS). This chemical analysis allowed discriminating the four sensory poles, so the sensory discrimination seemed to be mainly based on volatile compounds. Then, the key odorants responsible for chocolates differen…
Développement de méthodes de référence pour les biomarqueurs du bilan lipidique : application au contrôle qualité en biologie clinique
2013
Reliable measurements in medical biology are essential for early screening and appropriate follow-up of patients. Ensuring metrological traceability of clinical measurements to higher order reference methods or certified reference materials enables to obtain comparable results over time and between different laboratories that could use different methods to quantify the same biomarker.In this study, reference methods were developed and validated for lipid profile biomarkers (total cholesterol, triglycerides, HDL-C, and LDL-C). Their value added in proficiency testing schemes was demonstrated against consensus mean. They were also used to characterize a certified reference material (CRM) that…
Sur la piste des matériaux organiques grâce à la spectrométrie de masse
2018
Identifying the organic materials present, establishing their origin and degree of preservation, understanding their manufacturing process and their use, all of which require interdisciplinary studies involving closely specialists in materials and human sciences. In this very specific context, mass spectrometry has become a key tool to improve knowledge of past civilizations but also to better preserve and restore the discrete remains of archaeomaterials. The identification of diagnostic molecular markers of natural substances is now a recognized strategy for characterizing amorphous organic materials (fats, beeswaxes, vegetable substances such as resins and tars). New advances have also ma…
The odour of human milk: Its chemical variability and detection by newborns
2019
International audience; Human milk odour has for long elicited research interest with regard to its function in breastfeeding initiation. The present review aims to provide an overview of the behavioural effects of human milk odour in the human neonate, considering different types of response measures in a feeding or non-feeding context. Further, an overview of the current knowledge of odorant composition and factors influencing milk odour is provided by summarizing results from analytical studies using olfactometry, and addressing changes in milk odour due to storage, lactational stage, and maternal dietary intake of odorous substances. We finally highlight some issues for future research.
Isolement et caractérisation de saponosides extraits de deux plantes médicinales : Cyclamen africanum, Zygophyllum cornutum et évalution de leur acti…
2014
The appearance of several diseases, such as cancer, diabetes, high blood pressure and spread of infections mutagenic virus type can be linked to the quality and lifestyle that we lead today. Indeed, several studies on the factors triggering these so-called "morbid" long-or short-term illnesses are related to stress and quality of food consumed, whether of plant and animal origin. These diseases are becoming a common occurrence, they affect different races and all classes of society. According ethnobotanical research, naturally occurring substances, allowed civilizations to survive deadly diseases. For example, we thus find references to periods of malarial fever in China and one of the symp…