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F Guyon

Publications and source records attributed to F Guyon.

At least 55 records · Page 3Linked to original sources
PubMed1995

[Rapid assay of plasma acetate by gas chromatography: evaluation and comparison with two other methods].

Human plasma acetate is derived from colonic fermentation of fiber and endogenous metabolism of dextrose and fatty acids. Acetate may have regulatory functions in hepatic carbohydrate metabolism. Intake of dietary fiber is associated with several beneficial effects on carbohydrates and lipids metabolisms. To study theses effects a valid and automated method for routine analysis of acetate in plasma is necessary. After oral administration of lactulose to healthy human volunteers, the concentration of plasma acetate was measured by head space gas chromatography (HS-GC), vacuum distillation gas chromatography (VD-GC) and enzymatic spectrometric method (ES). The method HS-GC was linear to 0.5 mmol.l-1 (n = 5, r = 0.998), the detection limit is 0.005 mmol.l-1. Within-day variation (CV) was 3.60% and day-to-day variation was 4.5% (0.1 mmol.l-1). The coefficients of correlation between CG-ET/CG-DsV and CG-ET/E-M are 0.903 (p = 0.0001) and 0.54 (p = 0.006) respectively, the mean square errors are respectively 0.118 and 0.138 mmol.l-1. The variation curves of plasma acetate measured by GC versus time show peak concentration of 0.323 to 0.380 mmol.l-1 at 120 min.

Acetates↗
PubMed1993

Separation and determination of warfarin enantiomers in human plasma samples by capillary zone electrophoresis using a methylated beta-cyclodextrin-containing electrolyte.

A methyl beta-cyclodextrin with a degree of substitution of 1.8 proved to be an effective chiral selector, among other cyclodextrins tested, for the separation of warfarin enantiomers by capillary electrophoresis. The operating conditions were optimized with respect to electrolyte composition (buffer pH, ionic strength, cyclodextrin concentration, methanol content) and applied voltage. The influence of a high ionic strength on the resolution was clearly shown. A baseline separation can be obtained in less than 15 min with an efficiency of ca. 250,000 theoretical plates. These conditions were applied to the determination of warfarin enantiomers in the plasma of patients under warfarin therapy. The limit of detection for the whole procedure (dichloromethane extraction followed by evaporation to dryness and capillary electrophoresis) was of the order of 0.2 mg/l (6.5.10(-7) M) of each enantiomer.

Cyclodextrins↗
PubMed1990

[Pleural symphysis with tetracyclines for pneumothorax. The value of thoracic peridural analgesia].

The aim of this study was to assess the value of peridural thoracic analgesia (ATP) to prevent pain observed during pleural symphysis with tetracycline (STP) for pneumothorax (PNO). 12 patients (age 27 +/- 6 years) having a spontaneous PNO benefited from 13 SPT (1 gm, tetracycline diluted in 60 cc of normal saline) under cover of an APT (at the D5-D6 level) with Fentanyl (0.1 mg) and Bupivacaine 0.5% adrenalin (1 mg/kg). The protocol was used on three successive days. Repeated determinations of blood bupivacaine levels were performed in 9 patients on the first day. No patient had an intolerable pain which required injection of parenteral morphine and/or an interruption of the protocol. For two patients (one of them having a right symphysis and then a left symphysis one month later) the treatment sessions to achieve a symphysis were totally painless. 10 patients experienced moderate pain, mainly on the first day, which was relieved by reinjection of peridural bupivacaine (25 mg) (n = 9) or by the parenteral injection of non morphine analgesia (n = 1). No patient had a respiratory depression, collapse or bradycardia. The blood bupivacaine levels were always significantly less than the toxic levels (1.6 mg). The results observed suggest that APT, (Fentanyl and Bupivacaine) is an effective method, non toxic and well tolerated for the prevention of intolerable pain which is seen in SPT for PNO.

Adult↗
PubMed1989

Assessment of topical non-steroidal anti-inflammatory drugs.

A new non-invasive technique for assessing the efficacy of topical non-steroidal anti-inflammatory drugs (NSAID) in man is proposed. The NSAID are initially applied to the skin under occlusion before inflammation is induced by a methyl nicotinate solution. The inflammatory response is quantified in terms of cutaneous blood flow by a laser Doppler velocimeter (LDV). The efficacy of NSAID preparations is calculated by comparing the responses of the LDV to the methyl nicotinate challenge on the pretreated and the non-treated skin sites. This protocol has been used to investigate the effect of three different NSAID preparations (indomethacin, niflumic acid, palmitoyl collagenic acid) and the influence of the vehicle on the efficacy of indomethacin. The three preparations tested gave positive results but with different amplitudes in response. The efficacy of indomethacin varied with the vehicle used.

Administration, Topical↗
PubMed1988

[Dosage adjustment of metoclopramide for controlling vomiting induced by cisplatin: pharmacokinetic approach].

Ten patients under cisplatin-containing chemotherapeutic regimens received constant rate continuous infusions of metoclopramide in doses adjusted to each individual case for optimal plasma concentration. Dosage adjustment was based on simple pharmacokinetics with determination of metoclopramide distribution and elimination values in each patient. From these values were calculated the individual loading and maintenance dosages required to obtain the sustained plasma concentration of 0.85 mg/l reported in the literature as being correlated with a good antiemetic effectiveness. The mean plasma concentration in the 10 patients studied was 0.84 +/- 0.19 mg/l with doses which varied considerably owing to marked scattering of pharmacokinetic parameters. Treatment was effective in 6 out of 10 patients and well tolerated by all.

Adult↗
PubMed1988

Automatic determination of urinary 4-hydroxy-3-methoxymandelic (vanillylmandelic) acid by liquid chromatography with electrochemical detection.

An automated liquid chromatographic method for the determination of urinary concentrations of 4-hydroxy-3-methoxymandelic acid (VMA) is described. Urine samples are purified by solid-phase extraction on an anion-exchange cartridge and automated on-line chromatographic elution is carried out using a Varian AASP (advanced automated sample processor) system. The column effluent is monitored with an electrochemical detector using a glassy carbon working electrode. The method allows the determination of VMA in 0.05 ml of normal urine with a relative standard deviation of less than 3%. The analysis time can be shortened by use of back-flushing technique, and the correlation with a classical (but non-automated) VMA analysis method is excellent.

Chromatography, High Pressure Liquid↗
PubMed1988

[Determination of glycosylated hemoglobin HbA1c by liquid phase chromatography].

Glycated hemoglobin A1c assay is performed using HPLC on cation exchange TSK SP 5 PW column. Separation is obtained in 11 minutes using graduated elution with sodium chloride and Bis-Tris buffer. HBA1c is resolved from the other hemoglobins (A1a, A1b, Ao, F, S, C). Reproducibility of method is quite good (cv less than 3%) and correlated with classic low pressure chromatographic analysis using cation exchange resin.

Chromatography, High Pressure Liquid↗
PubMed1987

[Inhalation pneumonia presenting as a pneumocystis infection].

A case of Pneumocystis carinii pneumonia is presented. Following presentation a chronic alveolitis was uncovered, which was due to ultimately repeated and prolonged inhalation of sweets containing gum arabic. The diagnosis was confirmed by a trans-bronchial biopsy and by chemical analysis of centrifugation of the alveolar lavage deposit. After cessation of the inhalation the progress was satisfactory both in terms of clinical status and lung function measurement.

Gum Arabic↗
PubMed1987

[Assay of clomipramine and its demethylated derivative by liquid chromatography].

Clomipramine and desmethylclomipramide are determined on 1 ml of human blood plasma, after extraction with hexane and high-performance liquid chromatography using a cyanopropyl silane column and UV detection at 280 nm. Imipramine and desipramine are used as internal standards. The methods allow detection limits of 5 micrograms/l; 15.9 nmol/l (clomipramine) to 10 micrograms/l; 33.2 nmol/l (desmethylclomipramine). The precision of the method at clomipramine concentrations of 0.05 to 0.2 mg/l was indicated by a coefficient of variations less than 6% for clomipramine and less than 7% for desmethylclomipramine.

Chromatography, Liquid↗
PubMed1986

High performance liquid chromatography of procainamide and N-acetylprocainamide in human blood plasma.

Procainamide is used in antiarrhythmic therapy, and the need to monitor the drug concentration as well as its major plasma metabolite, N-acetyl-procainamide, is well established. An assay designed for the routine clinical therapeutic drug monitoring laboratory has been developed. A 0.5-ml aliquot of blood plasma is treated with 0.1 ml of internal standard solution, and the mixture is alkalinized. The drug, its metabolite, and the internal standard, N-propionyl procainamide are extracted with methylene chloride. After evaporation to dryness and addition of 0.3 ml of mobile phase, a volume of 0.1 ml is injected onto a liquid chromatograph equipped with spectrofluorimetric detection, which has a better specificity than UV absorptiometric detection. The between-day coefficient of variation was 3.5% for procainamide and 5% for N-acetylprocainamide. The sensitivity of this technique permits detection of 0.1 micrograms/ml of procainamide and 0.25 micrograms/ml of N-acetylprocainamide. Several drugs that are often present in patients receiving procainamide were shown not to interfere.

Acecainide↗
PubMed1986

[Resistance to vitamin K antagonists. 6 cases].

Haemorrhage is the most frequent complication of oral anticoagulant therapy (OAT) and a resistance to these drugs is rarely reported. The following classification of OAT resistance is proposed: primary or secondary resistance according to the delay of onset (at the initiation of therapy or later); selective or generalized according to the number of drugs involved (only one or several); absolute or relative as judged by the prolongation of the prothrombin time (absent or moderate). Six cases are reported and the mechanisms of resistance are discussed: no intake, variations in the vitamin K availability (diet, intestinal absorption and synthesis of vitamin K), variations in the pharmacokinetics of oral anticoagulants (drug interactions, abnormal hepatic metabolism) and variations in the receptor affinity (hereditary resistance). Resistance is often overcome by progressive increase of the doses of oral coagulant, or by changing drugs, to warfarin or coumadin (long acting drugs).

Adult↗
PubMed1986

[Intravenous theophylline: adaptation of dosage to blood theophylline levels at admission and to clearance].

Intravenous infusions of aminophylline expose the patient to the risk of overdosage related to the narrow safety margin of the therapeutic concentrations and to the great individual variability of its excretion. The aim of this study was to evaluate a simplified protocol designed to determine the optimal dose of theophylline based on total body clearance. Forty-four patients (average age: 63 years) admitted with decompensation of chronic respiratory failure (N = 33) or with status asthmaticus (N = 11) were studied. Theophylline was administered initially at a constant rate R0 (mg/kg/h) depending on serum theophylline concentrations on admission T0 (mg/l): R0 = 0.75 - 0.75 T0/20. Serum theophylline concentrations were measured at the 6th and 12th hours (T6 and T12) for calculation of clearance (Chiou et al. J. Pharmacokinet. Biopharm., 1978, 6, 135-151) and for adjusting dosage R. After 48 hours of treatment at this infusion rate, serum theophylline was again measured (T48) to check the adjustment of the dosage and recalculate clearance. In 11 patients T0 was greater than 15 mg/l (max = 44) and T12 was 10.5 +/- 6.4 mg/l. Theophylline was withdrawn in 6 patients with initial clearances less than 5 ml/kg/h (zero in 5 cases). T48 was within therapeutic values (10-20 mg/l) in 55 p. 100 of cases (21/38). Twelve patients had T48 less than 10 mg/l due to an increase in theophylline clearance (+ 80 p. 100 on average) related to improved right ventricular function in 7 cases. In 5 patients T48 was greater than 20 mg/l (max = 27.5) due to a fall in clearance (average -47 p. 100) which could have been caused by administration of erythromycin in 1 case and by dose-dependent kinetics in 2 cases. This protocol which is simple to carry out in practice allows early adjustment of dosage to give effective serum theophylline concentrations in over 50 p. 100 of cases. No serious cases of overdosage were observed, even in patients with high T0 and/or low initial clearances. Under-dosage and overdosage are related to large individual variations in theophylline clearance.

Aged↗