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Biomedical subjects

P Prognon

Publications and source records attributed to P Prognon.

At least 55 records · Page 3Linked to original sources
PubMed1989

A rapid and specific extraction procedure for folates determination in rat liver and analysis by high-performance liquid chromatography with fluorometric detection.

The native fluorescence of the main biological derivatives of folic acid is maximal at acidic pH. The intensities obtained with 5-methyltetrahydrofolic acid, tetrahydrofolic acid, and formyltetrahydrofolic acid are in the ratio 10/5/1. After separating the metabolites by reversed phase high-performance liquid chromatography, the fluorometric detection limit varied between 0.4 and 20 pmol per injection. Rat liver extract (about 2 g/50 ml of 1% ascorbate solution) could be analyzed after incubation at 37 degrees C overnight, deproteinizing with acetone, and purification and concentration in an ion exchange column. The concentrations obtained varied from 1.27 to 7.96 nmol/g depending on the derivative. Recovery varied from 89 to 113%.

Animals↗
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↗
PubMed1987

Various techniques for the routine evaluation of the degradation of glucose in parenteral solutions--a critical study.

A practical approach is described for studying the influence of various physicochemical factors on the degradation of glucose in parenteral solutions sterilized by heating in an autoclave. Five routine analytical methods are discussed: pH determination; direct ultraviolet absorption measurement (BP) method; liquid chromatography of 5-HMF; thin-layer chromatography of sugars, carboxylic acids and carbonyl species; and enzymatic determination of glucose. The effects of various factors on the degradation of glucose were studied: glucose concentration (10%, 30%, 50%); pH of solution before sterilization (2-10); sterilization cycle (103 min at 110 degrees C, 20 min at 120 degrees C, 3 min at 134 degrees C; same Fo); time of heating at 120 degrees C (30, 40, 60 min); and the presence of salts (sodium acetate, sodium lactate, sodium chloride). The results demonstrate the importance of these factors in influencing the rate of glucose degradation during sterilization. In the presence of salts, 5-HMF is not the most important product of degradation and the BP assay is not suitable for evaluation of glucose breakdown. The authors propose two control procedures. For simple solutions of glucose, the BP method is suitable. In the presence of salts the glucose oxidase method should be used.

Journal Article↗
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↗
PubMed1984

The metabolism of 8-methoxypsoralen by Saccharomyces cerevisiae. Evidence for an inducing effect of ethanol.

The metabolism of 8-methoxypsoralen (8-MOP) by the yeast Saccharomyces cerevisiae has been investigated in order to determine if this cell system could provide a simple model to study the metabolism of new photosensitizing drugs in vitro. 8-MOP was found to be rapidly metabolized by S. cerevisiae in non growing conditions. A metabolite was detected which exhibits a structure similar to that of a metabolite previously isolated in dog and man. Ethanol showed a strong inducing effect on 8-MOP metabolization.

Biotransformation↗
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↗
PubMed1983

Photobiological activity of suction blister fluid from patients treated with 8-methoxypsoralen.

Suction blister fluid was collected from normal human volunteers before (SBF) and 2 h after (SBF 8-MOP) oral 8-methoxypsoralen (0.6 mg/kg) ingestion without irradiation. In SBF 8-MOP the concentration of 8-MOP was 150 ng/ml, and fluorescent metabolites were also present. The toxicity of SBF 8-MOP was then determined with and without UV-A irradiation in the diploid strain D7 of the yeast Saccharomyces cerevisiae which is suitable for the detection of lethal, mutagenic and recombinogenic events. It was compared with that of SBF, SBF with 8-MOP added in vitro (150 ng/ml) and 8-MOP (150 ng/ml) in water. SBF showed no effect with UV-A doses up to 360 kJ m-2; SBF 8-MOP showed a slight decrease in survival and a dose-dependent increase in nuclear mutations, mitotic gene conversion and crossing over; SBF with 8-MOP added in vitro showed increased photobiological activity compared with SBF 8-MOP. This photobiological activity was increased by a factor of six when using 8-MOP in water. These results indicate a different bioavailability of 8-MOP in water and in interstitial fluid containing proteins. The metabolites of 8-MOP in human skin did not increase the photobiological activity of the drug. We conclude that the 8-MOP present in human skin during PUVA therapy is mutagenic and recombinogenic for eukaryotic cells.

Biological Availability↗
PubMedDate not supplied

Development of a standard, freeze-dried serum containing the drugs assayed most often in French hospitals.

A quality control program for the therapeutic drug monitoring methodology used to determine serum levels of the fourteen drugs assayed most frequently by French hospital laboratories is described. The program has been adopted by the Societé Française de Biologie Clinique (SFBC), which provides participating laboratories with a statistical analysis of the performance data. The control samples developed for the program are prepared by spiking calf serum with, in one case, phenobarbital, phenytoin, carbamazepine, sodium valproate, amikacin, lithium carbonate, digitoxin and hydroquinidine, and, in the other case, caffeine, quinidine, digoxin, isoniazid and gentamycin. After freeze-drying the spiked serum, the drugs were shown to be stable for at least a year when stored at -20 degrees, +4 degrees and +22 degrees; at the end of this time, the samples were pathogen free. For checking therapeutic drug monitoring methods, the freeze-dried serum is diluted with distilled water (10 ml); these solutions are chemically stable, and remain pathogen-free, when stored in stoppered glass tubes at -20 degrees or +4 degrees for 4 weeks.

Drug Contamination↗
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↗