From molecular model to sparse representation of chromatographic signals with an unknown number of peaks.

Analysis of a fluid mixture using a chromatographic system is a standard technique for many biomedical applications such as in-vitro diagnostic of body fluids or air and water quality assessment. The analysis is often dedicated towards a set of molecules or biomarkers. However, due to the fluid complexity, the number of mixture components is often larger than the list of targeted molecules. In order to get an analysis as exhaustive as possible and also to take into account possible interferences, it is important to identify and to quantify all the components that are included in the chromatographic signal. Thus the signal processing aims to reconstruct a list of an unknown number of components and their relative concentrations. We address this question as a problem of sparse representation of a chromatographic signal. The innovative representation is based on a stochastic forward model describing the transport of elementary molecules in the chromatography column as a molecular random walk. We investigate three methods: two probabilistic Bayesian approaches, one parametric and one non-parametric, and a determinist approach based on a parsimonious decomposition on a dictionary basis. We examine the performances of these 3 approaches on an experimental case dedicated to the analysis of mixtures of the micro-pollutants Polycyclic Aromatic Hydrocarbons (PAH) in a methanol solution in two cases of high and low signal to noise ratio (SNR).

Validation of a new calibration method for human muscle microdialysis at rest and during exercise.

Microdialysis presents the unique possibility to measure metabolite concentrations in human interstitial fluid. During exercise, the recovery of these metabolites should be precisely monitored since it is known to increase greatly with muscle blood flow. The loss of ethanol, perfused at low concentration, can be accurately measured and reflects the changes in dialysis conditions. We evaluated whether using the relationship determined in resting metabolic conditions between the loss of ethanol, as reference substance, and the recovery for lactate or glucose would allow us to calculate precisely the concentration of these substances and their variations during exercise. Using the new catheter calibration method (slope method), the error of estimation of lactate and glucose in vitro was limited to -0.6 (5.8)% and -0.7 (6.2)%, respectively. In resting human muscle, the slope method proved to be as accurate as an established calibration technique ("no net flux method") to evaluate interstitial lactate concentration [1.82 (0.58) vs 1.83 (0.47) mM, respectively]. During dynamic knee-extension exercise or light neuromuscular electrical stimulation, the estimated interstitial lactate and glucose concentrations varied differently, but their time course changes remained consistent with their respective plasma values. We conclude that, after an initial calibration step, the slope method allows accurate measurement of interstitial muscle metabolites and it could be used to monitor rapid metabolic changes during exercise.

[Adverse effects: priapism caused by paroxetine]. / Effet détonant : priapisme sous paroxétine.

The case of a young man with depressive illness who developed priapism while being treated with paroxetine is reported for the first time. Other sexual side effects are reported with paroxetine : delayed ejaculation, anorgasmy, erectile dysfunction and decreased libido. Other antidepressants are known to cause priapism : fluoxetine and especially trazodone.

Effect of contralateral acoustic stimulation on the growth of click-evoked otoacoustic emissions in humans.

Input-output (I/O) functions of click-evoked otoacoustic emissions (CEOAEs) were obtained over a 12 dB range for 64 normally hearing adult listeners with and without contralateral broadband noise (BBN). Contralateral acoustic stimulation (CAS) is a convenient way of suppressing responses to ipsilateral stimuli, probably acting via the medial olivocochlear system (MOCS). The present study shows that this contralateral sound suppression of CEOAEs is largest at low stimulus levels. In fact, the curves obtained under CAS approach the curves obtained without CAS as stimulus level rises. I/O slope analysis for the whole study population (n = 64) showed a slight but significant rise in slope with BBN, which may be interpreted as I/O function decompression. A loss of contralateral suppression effect at high ipsilateral stimulus levels was found in both very low and very high amplitude CEOAE subjects, despite the fact that I/O slopes differed between these two groups, whereas rise in slope under contralateral stimulation failed to be found for these same 2 groups of 16 subjects each. These findings clearly indicate that the MOCS is mostly functional at low sound levels, and suggest that the study of CEOAE I/O slope alteration under CAS may help specify one form of MOCS action on cochlear functioning.

[Lithium therapy and drinking water]. / Lithiothérapie et eaux de boissons.

ain causes of failure and giving up in psychotropic lithiotherapics because of instable lithiemy to the same patient or functional acute renal insufficiency, are principaly mistaken diets, those mistaken concerning the amount, the quality and the way of taking drinking water and other beverages. Lithium salt, taken either in two times, morning and evening, or in one, must be absorbed at the end of a solid meal with at least 25 cl. of water. The patient must absorb at least 1.5 l. of water per day, and up to 3 l. in case of physical efforts or heat. The pH of this water and it ionic compound should be stable, as close as possible to the plasma's, without additives that could change its taste. This includes cooking water and infusions. Physicopharmacological explanations.

[District statistical study in 1992]. / Les chroniques du secteur: étude statistique en 1992.

The statistical study of the population taken in increased charge by the extra-hospital care team, sector G of the Marne, shows that this population comprises essentially psychotic patients, their pathology having lead them to uprootedness, solitude and loss of financial autonomy. The stabilization of these patients constitutes an extra-hospital chronicization and the risk of abusive "externement" has always to be weighted.

[Benzodiazepine drug ingestion and evaluation of after care]. / Ingestions médicamenteuses aux benzodiazépines et évaluation de la vigilance.

Voluntary drug ingestion with benzodiazepine represent today the most frequent method of attempt of autolysis. One must note the difficulties the doctor may find in front such problems to judge the reliability of interviews made in such difficult conditions. Residual disturbances of superior functions, more precisely of vigilance during the period with follow the suicidal action must not be overlooked. Thanks to a clinical scale easily used the residual disturbances have been put in evidence on a sample of 20 subjects who had been admitted with this aim in view in a university ward specialized in psychiatric emergencies. The possibility of continuity within middle range care must allow an improvement of minimum care of such pathologies.