PubMed Health⌕ Search

Biomedical subjects

P Chaminade

Publications and source records attributed to P Chaminade.

17 recordsLinked to original sources
PubMed2006

Liquid chromatography on porous graphitic carbon with atmospheric pressure photoionization mass spectrometry and tandem mass spectrometry for the analysis of glycosphingolipids.

The study of several structural variations (the length, the degree of unsaturation and hydroxylation of the alkyl chains, the number and nature of osidic residues) helped understand the behaviour of neutral glycosphingolipids (GSLs) on porous graphitic carbon stationary phase (PGC). Atmospheric pressure photoionization mass spectrometry (APPI) and tandem mass spectrometry were used to perform the detection and the identification of molecular species in positive mode where [M+H](+) and [M-H(2)O+H](+) ions provided structural information on the fatty acid and the sphingoid base. The retention of GSLs increased with the hydrocarboneous volume of their alkyl chains and with the number of osidic residues in agreement with hydrophobic properties and polar retention effect of graphite, respectively. The presence of polar groups, such as OH-group or double bond within alkyl chains, decreased their retention. The coupling of chromatography on PGC with APPI tandem mass spectrometry detection appeared a powerful technique to discriminate isobaric molecules. Isobaric solutes differing by the position of two double bonds or by the repartition of hydrocarboneous skeleton were discriminated according to their chromatographic comportment or their mass spectrum, respectively. Among isobaric molecules, only few structures differing by the nature of osidic residue were not discriminated (i.e. glucosylceramide and galactosylceramide with similar ceramide skeleton were co-eluted and no difference in mass spectra was observed).

Atmospheric Pressure↗
PubMed2006

Near infrared spectroscopy and process analytical technology to master the process of busulfan paediatric capsules in a university hospital.

The prescription of unlicensed oral medicines in paediatrics leads the hospital pharmacists to compound hard capsules, such as busulfan, an alkylating agent prescribed in preparative regimens for bone marrow transplantation. In this study, we have investigated how the general principle of process analytical technology (PAT) can be implemented at the small size of our hospital pharmacy manufacturing unit. Near infrared spectroscopy (NIRS) was calibrated for raw material identification, blend uniformity analysis and final content uniformity of busulfan hard capsules of 11 different strengths. Measurements were performed on capsules from 2 to 40 mg (n=440). After optimisation, accuracy and linearity of the NIRS quantitative method was demonstrated after comparison with a previously validated quantitative high performance thin layer chromatography (HPTLC) method. Such a comparison led to attractive NIRS precision: +/-0.7 to +/-1.0 mg for capsules from 2 to 40 mg, respectively. As NIRS is a rapid and non-destructive technique, the individual control of a whole batch of busulfan paediatric capsules intended to be administrated is possible. Actually, mastering the process of busulfan paediatric capsules with the NIRS integrated into the notion of PAT is a powerful analytical tool to assess the process quality and to perform content uniformity of at least 5mg busulfan-containing capsules.

Alkylating Agents↗
PubMed2006

[Imaging mass spectrometry: a new tool for the analysis of skin biopsy. Application in Fabry's disease].

The advent of innovative techniques in mass spectrometry, especially in the area of imaging, prompted us to evaluate two promising techniques: secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. For this purpose, sections of cutaneous biopsies from patients affected by Fabry's disease and control patients were analyzed. In the course of this disease, two physiological glycosphingolipids [globotriasylceramide (Gb3) and the galabiosylceramide (Ga2)] accumulate in certain tissues owing to a catabolism failure. The ability of these techniques to localize sites of accumulation in body tissues and their capacity to identify the accumulated lipid structures by mass spectra were evaluated. Results demonstrated that these two techniques provide complementary information:-secondary ion mass spectrometry enabled precise localization of areas of accumulation with lateral resolution in the micrometer range;-the signal obtained with matrix-assisted laser desorption/ionization mass spectrometry was high enough to identify these structures according to their molecular weight.

Diagnostic Imaging↗
PubMed2005

Modelling of ceramide interactions with porous graphite carbon in non-aqueous liquid chromatography.

Interactions of solutes on porous graphitic carbon (PGC) with non-aqueous mobile phases are studied by the linear solvation energy relationship (LSER). Studies have been carried out with eight binary mixtures composed of a weak solvent (acetonitrile or methanol) and a strong solvent (tetrahydrofuran, n-butanol, CH2Cl2, 1,1,2-trichloro-2,2,1-trifluoroethane). The systematic analysis of a set of test compounds was performed for each solvent mixture in isocratic mode (50:50). The results were compared to those obtained on PGC with hydro-organic liquids and supercritical fluids. They were then correlated with the observed retention behaviour of lipid compounds, more particularly ceramides.

Ceramides↗
PubMed2005

Fluorescence probe assisted post-column detection for lipid analysis in microbore-LC.

A general approach, still few exploited so far and never associated with microbore-LC, consisting of detection of various lipid classes (i.e. phospholipids, triglycerides, ceramides and glycosphingolipids) by non-covalent association with 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence probe is developed. This mode of detection was coupled with non-aqueous reversed-phase microbore-LC (C18) by using classical post-column fluorescence detection. The classical LC system was first adapted to microbore-chromatography (internal diameter 1 mm) without apparatus miniaturization of the solvent delivery system and the detection cell. For this purpose, the detection parameters (probe concentration, post-column flow rate, post-column reactor length and post-column system temperature) were optimized by a central composite design (CCD) using a mixture of phosphatidylcholine (PC) species as a lipid model and DPH (lambda(ex) = 350 nm, lambda(em) = 430 nm) as a fluorescence probe. The optimal conditions of detection for the various molecular species of PC were determined for a DPH concentration of 3.35 micromol/L, a post-column flow rate of 0.5 mL/min, a reactor length of 1.4 m and a temperature of 35 degrees C. The fluorescence response was linear over a wide range of PC species from 5 microg/mL to 100 microg/mL and the lower limit of detection (signal/noise = 3) was about 1 microg/mL, that is equivalent to evaporative light scattering detection (ELSD). Others molecular species of various classes of lipids, i.e. triglycerides, ceramides and glycosphingolipids were also easily detected. Thus, this study demonstrated the versatility of the proposed system of detection which was shown to be sensitive, easy to perform, non-destructive and allowed, in contrast to ELSD, for a linear response with various polarity lipid classes.

Chromatography, Liquid↗
PubMed2004

Optimisation of the separation of four major neutral glycosphingolipids: application to a rapid and simple detection of urinary globotriaosylceramide in Fabry disease.

A simple method for the separation of the four major neutral glycosphingolipids, present in all human tissue, was developed. This gradient normal phase-HPLC method utilises a polyvinyl alcohol bonded stationary phase and an evaporative light-scattering detection (ELSD). Screening pure solvents in a binary gradient elution mode allowed, in a first step, to assess the behaviour of the studied solutes and to select the solvents for further mobile phase optimisation. The proportion of the remaining solvents was defined to reach a maximal resolution. The reduction of the analysis time and the enhancement of the signal were obtained by optimising the gradient slope and the flow-rate. Optimal levels of triethylamine and formic acid (TEA-FA) for the enhancement of the evaporative light scattering detector response were established at 0.1% (v/v). Thus, the optimal conditions for the separation of the four glycosphingolipids was obtained with a gradient elution from a 100% chloroform to a 100% acetone:methanol (90:10 (v/v)) mobile phase at 0.2 ml min-1, using a 10% min-1 gradient slope. Finally, this method was applied to detect the excess of one of the neutral sphingolipids, namely globotriaosylceramide (Gb3) in the urine of patients affected with Fabry disease. A liquid-liquid extraction of the sediments obtained from an aliquot of only ten ml of urine proved sufficient to detect the excess of Gb3 present in both hemizygote and heterozygote patients. In all, the ability of our method to detect abnormal amounts of Gb3 in urinary sediments could allow the diagnosis of weakly symptomatic Fabry patients in large screening programs

Chromatography, High Pressure Liquid↗
PubMed2003

The benefit of the retrofitting of a conventional LC system to micro LC: a practical evaluation in the field of bioanalysis with fluorimetric detection.

The interests in liquid micro-chromatography (higher column efficiencies, increase in sensitivity) are now well established. The enhancement of fluorimetric response induced by the reduction of the inner diameter of columns (4.6, 3.0, 1.0 and 0.3 mm respectively) coupled with adapted detection cells to control the loss of efficiency (8 micro L for the two first columns and 100 nL for the two smaller ones) has been studied in the bioanalytical field, using the plasma determination of native fluorescent antibacterial agents: fluoroquinolones. Ten-fold enhancement of the signal can easily be obtained when substituting a 0.3 mm i.d. column and 100 nL detection cell for a 4.6 mm i.d. column, and 8 micro L detection cell. In addition to inner diameter reduction, the detection cell geometry appears to be an essential parameter to obtain the best enhancement of the recorded signal. Hence, the enhancement of signal with micro-chromatography with fluorimetric detection appears to be a compromise between column inner diameter and flow cell volume reduction.

Chromatography, Liquid↗
PubMed2001

Assessment of the retention properties of poly(vinyl alcohol) stationary phase for lipid class profiling in liquid chromatography.

Potentialities of polymerized vinyl alcohol on silica gel were assessed for class separation of simple lipids, sphingolipids, glyceroglycolipids and phospholipids by high-performance liquid chromatography. A screening of pure solvents in binary gradient elution and a chemometric approach was used to define a rugged two segment linear gradient formed from four solvents for total lipid class separation. Triethylamine and formic acid were added in all mobile phase components for acidic phospholipid separation and evaporative light scattering response enhancement. Simple analytical procedures are described for the analysis of complex lipid materials.

Chromatography, High Pressure Liquid↗
PubMed2001

Structural analysis of commercial ceramides by gas chromatography-mass spectrometry.

A simple method using gas chromatography-mass spectrometry was applied to analyse structures of ceramides. Identification of trimethylsilylated ceramides were obtained in short analysis times (derivatization of ceramides in 30 min at room temperature and 20 min gas chromatography mass spectrometry run) even for complex mixtures. For example in ceramide Type III, 18 peaks were observed which represent 27 various structures. The coeluted compounds were ceramides containing the same functional groups and the same carbon number but with a different distribution on the two alkyl chains of the molecule. They were accurately differentiated by mass spectrometry. Therefore, 83 structures of trimethylsilylated ceramides were identified in 11 different commercial mixtures. For 52 structures of these, mass spectral data were not described in the literature, neither full mass spectra nor characteristic fragments.

Ceramides↗
PubMed2001

Tamoxifen encapsulation within polyethylene glycol-coated nanospheres. A new antiestrogen formulation.

When dealing with solid tumors in vivo, pegylated long-circulating carrier systems show, after intravenous administration, an attractive extravasation profile with an enhanced localization in the tumoral interstitium. These systems could be of help for the delivery of cancer fighting drugs, such as Tamoxifen, a well known antiestrogen used in breast cancer therapy that possesses an extended biodistribution in vivo. This work aimed at encapsulating Tamoxifen in long-circulating poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) 1:4 nanospheres. Tamoxifen-loaded poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) nanospheres were successfully synthesized and characterized in terms of hydrophilicity/hydrophobicity by a model made up from near infrared spectra using principal component analysis. Zeta potential, drug loading, encapsulation efficiency, as well as biological effect, in vitro release and nanospheres integrity were also investigated. Even though near infrared spectroscopy could not detect Tamoxifen, it revealed that Pluronic F68 was associated with the pegylated nanospheres. HPLC measurements demonstrated that Tamoxifen was encapsulated in the pegylated nanospheres following a partition equilibrium between the polymeric and the aqueous phases. The Tamoxifen encapsulated in the nanospheres still showed a transcription inhibitory activity in ex vivo experiments. However, zeta potential and in vitro release suggested that Tamoxifen was essentially localized at the nanoparticles surface, resulting in an important and immediate drug release.

Drug Delivery Systems↗
PubMed2001

A direct sensitized fluorimetric determination of 5,10,15,20-tetra(m-hydroxyphenyl)chlorin [m-THPC (Foscan)] in human plasma using a cyclodextrin inclusion complex.

The 5,10,15,20-tetra(m-hydroxyphenyl)chlorin (m-THPC) (Foscan) is a photosensitizer used in the photodynamic therapy (PDT) of cancers which is currently under clinical trial. The formation of a m-THPC inclusion complex with dimethyl-beta-cyclodextrin (Me-beta-CD) in solution was demonstrated on the basis of circular dichroism experiments. A 1:2 complex stoichiometry was found and an inclusion constant beta 2 = 2.8(+/- 0.4) x 10(10) M-2 was determined. The formation of such a complex was shown to enhance the m-THPC fluorescence intensity. It could be exploited to improve the sensitivity of the direct m-THPC detection in human plasma. Optimization of the operating conditions shows that the best results were obtained by the addition of 100 microL of a concentrated Me-beta-CD solution (3.2 x 10(-2) M) to 1 mL plasma samples. Compared to the standard conditions, a 90% increase in sensitivity was obtained. The proposed analytical method which showed a linear response function [0-300 ng mL-1 (440 pM)] and a low limit of detection [1.5 ng mL-1 (2 pM) (S/N = 3)] appears, especially due to the absence of metabolism, a simple and specific method suitable for pharmacokinetics studies in patients.

Humans↗
PubMed2000

Retention behaviour of ceramides in sub-critical fluid chromatography in comparison with non-aqueous reversed-phase liquid chromatography.

This study was devoted to the development of an analytical method for ceramide analysis in packed subcritical fluid chromatography (pSubFC). Monofunctional grafted silica support was found to be more suitable for ceramide analysis. Five Kromasil columns were coupled and the parameters, temperature, pressure and percentage of organic modifier in CO2 were optimised, considering selectivity and analysis time. The final conditions were 31 degrees C, 6% of methanol (MeOH) and 13 MPa. In these conditions the selectivity for structural differences (methylene group, unsaturation or two different bases) were studied. As classically observed, the methylene selectivity decreased with the increase of the eluotropic strength. Moreover, unlike in non-aqueous reversed-phase liquid chromatography (NARP-LC), adding a further unsaturation and two further methylene groups on ceramide results to an increase of retention in pSubFC. Moreover, this last technique allowed to separate ceramides with the same total number of carbons containing unsaturated fatty acids, when the distribution of carbon number of the two chain is very different. These results had enabled to plot retention chart in order to predict ceramide structure in view to identify additional ceramide. This retention chart was finally compared with the one already obtained in NARP-LC.

Ceramides↗
PubMed2000

Near infrared with principal component analysis as a novel analytical approach for nanoparticle technology.

PURPOSE: To progress in the characterization of a poly(MePEGcyanoacrylate-co-hexadecylcyanoacrylate) (poly(PEGCA-co-HDCA) copolymer and the nanoparticles formed from this copolymer. METHODS: Poly(PEGCA-co-HDCA) at a MePEG/hexadecyl ratio of 1:4 was investigated by 1H-NMR and near infrared spectroscopy. The nanoparticle suspensions, obtained by the methods of nanoprecipitation or emulsion--solvent evaporation, as well as the crude nanoparticles and their dispersion medium--were analyzed by MePEG measurement, 1H-NMR, and near infrared spectroscopy. RESULTS: The 1H-NMR results showed that the (poly(PEGCA-co-HDCA) copolymer obtained bore lateral hydrophilic MePEG chains and lateral hydrophobic hexadecyl chains in a final ratio of 1:4. However, this ratio, although reproducible from batch to batch, represented only a mean value for different molecular species. Indeed, our results demonstrated the formation of more hydrophobic poly(alkyl-cyanoacrylate) oligomers (with a higher content of hexadecyl chains) and other more hydrophilic oligomers (with a higher MePEG content). Only the more hydrophobic oligomers were able to form solid pegylated nanoparticles. As far as these nanoparticles were concerned, determination of their MePEG content allowed the calculation of a distance of 1.2 nm and 1.05 nm between 2 grafted MePEG chains at the nanoparticle surface, when obtained by nanoprecipitation and emulsion-solvent evaporation, respectively. Moreover, when the same copolymer batch was used, different nanoparticles were obtained according to the preparation method, as seen by near infrared spectroscopy. CONCLUSIONS: The nanoparticles obtained by nanoprecipitation or emulsion-solvent evaporation of poly(PEGCA-co-HDCA) 1:4 copolymer displayed a different supramolecular organization, as evidenced by the near infrared spectroscopy results. Moreover, these nanoparticles showed surface characteristics compatible with a long circulating carrier.

Colloids↗
PubMed1999

Postcolumn fluorescence as an alternative to evaporative light scattering detection for ceramide analysis with gradient elution in non-aqueous reversed-phase liquid chromatography.

Ceramide analysis was developed with gradient elution in non-aqueous reversed-phase liquid chromatography with evaporative light scattering detection (ELSD) or postcolumn fluorescence detection. Fluorescence detection (excitation, 360 nm; emission, 425 nm) after postcolumn formation of mixed assemblies between eluted ceramides and 1,6-diphenyl-1,3,5-hexatriene was developed. In comparison with ELSD, fluorescence detection allows a better detection of the minor species ceramide from ceramide type III (commercial mixture of non-hydroxy fatty acid-sphingosine) and appears to be more sensitive for quantitation of ceramides at low concentrations. The fluorescence response is linear over a wide range of injected amount of ceramide III (expressed as stearoyl-phytosphingosine): 10 ng to 1000 ng. The response of ELSD is non linear but can be linearized in double logarithmic coordinates for calculations over a narrow range, e.g. between 10 to 350 ng ceramide III injected. The lower quantitation limits of these two detectors are similar: 5 ng ceramide III was injected.

Ceramides↗
PubMed1995

[Study of urinary excretion of codeine and morphine after oral ingestion of codeine].

Results of an investigation on the urinary excretion of codeine and morphine after oral ingestion of 1 mg.kg-1 b.w codeine are reported. The investigation run on seven clinically healthy subjects showed: low digestive absorption of codeine (# 20%); rapid biotransformation of codeine into morphine (first urines excreted after absorption); rapid disappearance of codeine from urines (#30 hrs); persistence of morphine alone (#68 hrs); rapid evolution of the codeine/morphine ratio (inversion of the ratio after #18 hrs); total elimination of morphine which can be greater than for codeine; very different half-life periods for codeine and morphine (5.1 and 13.6 hrs); no other codeine metabolites (nor-codeine and nor-morphine); very high individual variations; one subject with low activity of cytochrome P 450 dbl/buFL. Finally, in an epidemiological survey of drug addict behaviors and detection of drug addiction, it seems very difficult, may be even illusory and hazardous, to try and justify morphine found in urines (morphine, heroin, codeine, codethyline, pholcodine...) except in the very legitimate case where the ratio of urine concentrations of codeine and morphine is greater than one.

Administration, Oral↗
PubMedDate not supplied

Importance of the ionization states of m-THPC for its HPLC fluorescence detection.

An original, rapid and sensitive high-performance liquid chromatographic (HPLC) method has been developed for the detection of 5, 10, 15, 20 tetra-meso-hydroxyphenylchlorine (m-THPC), a photosensitizer used in the photodynamic therapy (PDT) of cancers. Chromatographic separation was carried out on a C(8) Zorbax column (80 x 4 mm, 5 microm). The mobile phase was an ethanol/aqueous sulphuric acid, pH 2.0 (65/35 v/v), in an isocratic mode yielding to rapid analysis (3.1 min) with narrow peaks. As the fluorescence intensity was found to be highly pH-dependent and to increase with pH values, a post-column device prior to the fluorescence detection (lambda(exc) = 423 nm, lambda(em) = 650 nm) was used to allow the addition of a 0.05 mol/L Na(2)HPO(4) solution to the mobile phase. Compared to standard conditions, a 300% increase of the fluorescence intensity was obtained for optimized operating conditions using experimental design. The validation of this analytical method showed that the response function was linear for concentrations up to 1000 microg/L (1.47 x 10(-6) mol/L) with a detection limit of 188 pg (S/N = 3).

Chromatography, High Pressure Liquid↗