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G Mahuzier

Publications and source records attributed to G Mahuzier.

At least 37 records · Page 2Linked to original sources
PubMed1993

[Luminescence and detection in liquid chromatography. I: Change of environment of analytes].

The emissions of light by biorganisms or these obtained by alchemists were known since long time ago but the are used in analytical chemistry only when STOKES discovered that the intensity of this light was proportional to the quantity of the matter. The very large sensibilities reached, associated with the great separation's ability of the liquid chromatography allows to develop new processes for quantification of very low concentrations of luminescent or no luminescent molecules. Many pharmaceutical, biological toxicological environmental or alimentary applications show that it is possible in liquid chromatography to obtain a detection limit about the pico or femtomole when simple chemical process are used: direct potentialization of luminescence by addition of modifiers of the chemical environment of the analytes: solvents, cyclodextrins, surfactants, metallic ions, indirect potentialization of the luminescence by transfer of energy from an excited molecule: sensitized fluorescence and phosphorescence, excitation of the molecule by a chemical reaction or chemiluminescence. These aspects are emphasized and illustrated by some examples in three articles.

Chromatography, Liquid↗
PubMed1989

Capillary gas chromatography and tandem mass spectrometry of paf-acether and analogs: absence of 1-O-alkyl-2-propionyl-sn-glycero-3-phosphocholine in human polymorphonuclear neutrophils.

Fast atom bombardment-tandem mass spectrometry was used to identify molecular species of paf-acether (paf) produced by human polymorphonuclear neutrophils. Using this biological material, normal phase high performance liquid chromatography was necessary prior to the fast atom bombardment-tandem mass spectrometry step. Gas liquid chromatography/electron capture detection after hydrolysis with phospholipase C and conversion to heptafluorobutyrate derivatives was used to confirm the results. The results indicated the presence of mainly 1-O-hexadecyl/octadecyl-2-acetyl-sn-glycero-3-phosphocholine, acyl analogs of paf and only trace amounts of other alkyl analogs of paf. We did not detect the 2-propionyl analog of paf. Moreover, supplementation of human polymorphonuclear neutrophils with sodium propionate did not result in formation of the 2-propionyl analog of paf.

Electrons↗
PubMed1989

Elimination of caffeine interference in HPLC determination of urinary nicotine and cotinine.

We report an analytical reversed-phase liquid-chromatographic procedure for quantifying nicotine and cotinine in urine, taking into account the presence of interfering caffeine frequently encountered in such specimens. These analytes are extracted from the alkalinized urine with chloroform. After evaporation of the chloroform, the residue is dissolved in methanol and injected into a chromatographic C18 column. Extraction recoveries averaged 80% to 97%. Chromatographic conditions were investigated to obviate caffeine interference. The proposed eluent mobile phase is a polar mixture of water, acetonitrile, methanol, and a pH 4 acetoacetate buffer (65/2/29/4 by vol) adjusted to pH 4.30 +/- 0.02 with triethylamine. High resolution and linearity were obtained for each analyte up to a concentration of 200 mg/L. The minimum detectable amount of each compound was 20 ng per injection, corresponding to 10 micrograms per liter of urine. Correlation with results of gas-liquid chromatography was excellent (r = 0.99). This simple, rapid procedure allows routine screening of tobacco exposure with acceptable precision: within- and between-run coefficients of variation were less than 2% and less than 5%, respectively.

Caffeine↗
PubMed1988

Relative affinity of 5-methoxypsoralen and 8-methoxypsoralen towards beta-cyclodextrin: a fluorescence, circular dichroism and chromatographic study.

The relative affinity of 5-methoxypsoralen (5-MOP) and 8-methoxypsoralen (8-MOP) towards beta-cyclodextrin, a good model for the study of lipophilic interactions in biological systems and a potential drug carrier, has been investigated using spectroscopic and chromatographic methods. The fluorescence emission of 5-MOP in aqueous solution containing beta-cyclodextrin (10(-2) M) is found to be markedly blue shifted and enhanced by a factor of 6 whereas no significant changes are observed for 8-MOP. The existence of an induced circular dichroism is evidence for the formation of a 1:1 inclusion complex (association constant K = 400 +/- 50 M-1). Moreover, chromatographic results obtained with a beta-cyclodextrin linked stationary phase are consistent with our spectroscopic results and might have interesting analytical implications. These results clearly demonstrate that, in contrast to 8-MOP, 5-MOP exhibits a strong affinity for hydrophobic medium. Interesting pharmacological and analytical applications may result from the possible inclusion of psoralen derivatives into beta-cyclodextrin.

5-Methoxypsoralen↗
PubMed1988

[Mass spectrometry of peptides].

Recent progress in biochemistry has shown the occurrence of many important peptides, among antibiotics, immunostimulants, hormones and neuromediators. The mass spectrometric study of these components by classical ionization techniques such as electron impact, chemical ionization or field desorption require a prior chemical derivatization because of their amphoteric properties, their low volatility and low thermostability. Recent improvements in methods of ionization, fast atom bombardment, secondary ion mass spectrometry, or mass spectrometry/mass spectrometry have made it possible to study the structure of peptides with more than 15 amino acid residues and eased mass spectra interpretation. Through the different methodologies described in this review three characteristic informations can be obtained concerning the molecular mass of peptides, the nature of constituent amino acids and the peptidic sequence and even quantitative measurements can be performed.

Chemical Phenomena↗
PubMed1987

Characterization and quantification of PAF-acether (platelet-activating factor) as a heptafluorobutyrate derivative of 1-O-alkyl-2-acetyl-sn-glycerol by capillary column gas chromatography with electron-capture detection.

A gas chromatographic method with a glass capillary column and electron-capture detection is proposed for the characterization and quantification of 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-phosphocholine (PAF C16) using the corresponding 1-O-hexadecyl-2-O-acetyl-sn-glycero-3-heptafluorobutyrate derivative and, as an internal standard, 1-O-octadecyl-2-O-methyl-sn-glycero-3-phosphocholine. The reproducibility was approximately 5% and amounts as low as 20 pg could be measured. The method was specific and allowed the quantification of PAF C16 in supernatants from stimulated human polymorphonuclear neutrophils.

Chromatography, Gas↗
PubMed1987

New antifilarial agents. 1. Epoxy sulfonamides and ethynesulfonamides.

Two series of 2-substituted 1,2-epoxyethanesulfonamides 2 and ethynesulfonamides 5 were synthesized and evaluated for their antifilarial activity. The trans epoxides 2T were stereospecifically prepared by a Darzens reaction between aldehydes and halomethanesulfonamides. The cis isomers 2c were obtained from ethynesulfonamides 5 by semihydrogenation followed by KOCl epoxidation. 2-Substituted ethynesulfonamides 5 were synthesized from appropriate trans-ethenesulfonamides by a bromination/dehydrobromination sequence. These products, as well as several synthetic intermediates, were evaluated for antifilarial activity against Molinema dessetae either in vivo in its natural host, the rodent Proechimys oris, or in vitro by a new test using cultures of the infective larvae. Most of the epoxides 2T and acetylenic derivatives 5 bearing a 2-aryl substituent were active in vitro. Among these compounds, four epoxides 2T and one acetylenic derivative 5 showed marked macrofilaricidal activity in vivo without any microfilaricidal activity. The differences between the in vivo and in vitro results may be due, in part, to the low chemical stability of the epoxy sulfonamides 2T. Despite this limitation, the activities observed in this reliable animal model suggest further development and testing of both series 2T and 5 as macrofilaricides.

Animals↗
PubMed1987

Role of volatile fatty acids in colonization resistance to Clostridium difficile in gnotobiotic mice.

Clostridium difficile is an agent involved in the development of antibiotic-associated pseudomembranous colitis. The purpose of this work was to investigate the role of volatile fatty acids (VFAs) in resistance to colonization by C. difficile by using a gnotobiotic animal model. Accordingly, germfree mice were associated with different hamster flora, and the VFAs in their cecal contents were measured by gas chromatography. The results showed that VFAs were produced mainly by the intestinal flora, especially by the strictly anaerobic bacteria. In these associated mice, the concentrations of acetic, propionic, and butyric acids were higher than those of other acids, but at pH 6.8 the MICs of these three acids in vitro for C. difficile were more than 200 mu eq/ml. In gnotobiotic mice monoassociated with C. difficile and in the isolated ceca of these mice, VFAs did not inhibit the growth of C. difficile. In gnotobiotic mice which were diassociated with C. difficile and C. butyricum and given drinking water with a lactose concentration of 20%, the cecal contents included about the same amount of butyric acid as did those of the monoassociated mice, although the population of C. difficile remained the same. Therefore, it is suggested that VFAs alone cannot inhibit intestinal colonization by C. difficile and that, consequently, other inhibitory mechanisms are also present.

Animals↗
PubMed1987

Binding of 3-carbethoxipsoralen to human serum albumin and human serum: influence of free fatty acids.

Characteristics of the binding of 3-carbethoxipsoralen (3CPS) to human serum albumin (HSA) and serum proteins have been studied. An electrophoretic study showed that the predominant binding protein fraction was albumin, with small binding to globulins. Binding to HSA, studied by equilibrium dialysis, is 75% and characterized by a small saturable number of binding sites (N = 0.27) with a moderate affinity constant (K = 8 X 10(4) M-1). Free fatty acids were shown to decrease 3CPS binding to HSA by a non competitive process.

Binding Sites↗
PubMed1987

[Determination of fosfomycin in biological fluids by gas chromatography].

A method in gas chromatography is proposed to determine fosfomycin in biological and bacterial or cellular culture medium. This technique is carried out on capillary column OV 17-01 after "Flash Methylation" with a thermionic detector. The detection limit is about 1 microgram per millilitre of serum for a trial assay of 100 microliters. His characteristics have been furthered. The treatment by antibiotics generally associated with fosfomycin don't cause any chromatographic interference for plasmatic assays.

Chromatography, Gas↗
PubMed1984

[Blood pharmacokinetics of fluorine in man after the oral administration of nicomethanol hydrofluoride].

The pharmacokinetic parameters of fluoride have been studied, after a single oral administration to human volunteers of two fluoridated compounds: sodium fluoride, and a new organic fluoride salt, nicomethanol hydrofluoride. The results obtained with these two compounds were very similar, suggesting that no abnormal accumulation of fluoride in the body occurs after using nicomethanol hydrofluoride.

Administration, Oral↗
PubMed1983

[Assay of 2-phenylbutyric acid in plasma with gas and liquid chromatography].

Two chromatographic methods which allow the measurement of 2-phenylbutyric acid in serum are described: a gas chromatographic, after silylation, and a reversed-phase high-performance liquid chromatographic. The liquid chromatography with a fluorescent detection, after derivatization by 4-bromomethyl-7-methoxycoumarin, is ten times more sensitive than gas chromatography and 50 ng/ml can be measured in biological liquids.

Chromatography, Gas↗
PubMed1983

Physicochemical properties and stability of anthralin in model systems and human skin.

The physico-chemical properties and the stability of anthralin, a potent antipsoriatic agent, has been investigated in model systems by optical absorption and fluorescence spectroscopy and by gas chromatography coupled to mass spectrometry. Systematic studies were carried out on anthralin and its oxidation products (1,8-dihydroxyanthraquinone and 1,8-1',8'-tetrahydroxydianthron). Anthralin and 1,8-dihydroxyanthraquinone are shown to readily bind to human serum albumin and not to DNA. Anthralin bound to albumin readily oxidizes, yielding the 1,8-dihydroxyanthraquinone which is fairly stable. These results are correlated with those obtained with intact whole human epidermis and suction blister fluid showing that, in the former case, anthralin binds to protein as suggested by absorption and fluorescence spectroscopies. Gas chromatography-mass spectrometry analysis makes it easy to detect anthralin and 1,8-dihydroxyanthraquinone in suction blister fluid doped with anthralin but not in suction blister obtained after topical application on normal human skin.

Anthracenes↗