PubMed Health⌕ Search

Biomedical subjects

M Guillaumont

Publications and source records attributed to M Guillaumont.

At least 19 recordsLinked to original sources
PubMed2005

Quantification of docetaxel and its main metabolites in human plasma by liquid chromatography/tandem mass spectrometry.

Docetaxel is an antineoplastic agent widely used in therapeutics. The objective of this study was to develop and validate a routine assay, using liquid chromatography coupled to tandem mass spectrometry (LC/MS/MS), for the simultaneous quantification of docetaxel and its main hydroxylated metabolites in human plasma. A structural analogue, paclitaxel, was used as the internal standard. Determination of docetaxel and four metabolites (M1, M2, M3 and M4) was achieved using only 100 microL of plasma. Liquid-liquid extraction was used for sample preparation, with extraction efficiency of at least 90% for all analytes. Detection used positive-mode electrospray ionization in selected reaction monitoring mode. The lower limit of quantification (LLOQ) was 0.5 ng/mL for all analytes. The assay was linear in the calibration curve range 0.5-1000 ng/mL and acceptable precision and accuracy (<15%) were obtained with concentrations above the LLOQ. This method was sufficiently selective and sensitive for quantification of metabolites in plasma from cancer patients receiving docetaxel chemotherapy, and is suitable for routine analyses during pharmacokinetic studies.

Antineoplastic Agents↗
PubMed1999

Laboratory data in healthy volunteers: reference values, reference changes, screening and laboratory adverse event limits in Phase I clinical trials.

OBJECTIVE: Laboratory data are key evaluation procedures for Phase I clinical pharmacology for two reasons. Firstly, laboratory data are used within the screening process to exclude subjects with asymptomatic diseases, which could result in increased danger to themselves or confuse interpretation of the study results. Secondly, during study implementation, safety evaluation and in particular maximum tolerated dose determination have to be done by a case-by-case analysis, sometimes using laboratory adverse events (LAEs). Thus, relevant limits are needed to discriminate between a usual common variation and a significant abnormality, which is considered to be a LAE. This report presents laboratory data distribution, reference values and reference changes and, based on previously published new methods, suggests inclusion limits at screening and laboratory adverse event limits for analysis during study implementation. SUBJECTS AND METHODS: Nine hundred and twenty-seven young healthy male volunteers were recruited in one centre (Association de Recherche Thérapeutique). A standard screening process was carried out. Protocols were approved by the local ethics committee. Blood sampling was performed in the same conditions. Reference values (at screening and at baseline) were determined by a non-parametric procedure selecting 2.5% and 97.5% of the distribution of data. Reference changes were also defined as the 2.5-97.5% interval of distribution of the variations between the end of treatment and baseline. Inclusion limit and LAE limit methods of determination used had been specified in previous articles. RESULTS: Detailed results of laboratory data distribution, reference values at screening and at baseline, reference changes, inclusion limits and LAE limits are presented in tables with number of subjects, mean, median, standard deviation, minimal and maximal values and the 2.5-97.5% interval for each laboratory parameter. CONCLUSION: The key aims of this paper are to provide clinical pharmacologists with data, reference values or changes obtained in the real conditions of Phase I study implementation, and to propose relevant limits, either for screening as inclusion limits, or during studies as LAE limits. Thus, these data, reference values and specific limits improve the capacity to screen healthy volunteers and to analyse LAEs during Phase I studies.

Adult↗
PubMed1993

Changes in hepatic vitamin K1 levels after prophylactic administration to the newborn.

We undertook a study of hepatic concentrations of vitamin K (vitamin K1 or phylloquinone, vitamin K1-epoxide, and menaquinones) in 18 infants, ages 1-8 days, with or without vitamin K1 supplementation. The infants who had no supplementation had a total hepatic storage ranging between 0.1 and 0.9 micrograms. Also, hepatic storage of phylloquinone was poor (< 1 microgram) when compared with daily requirements. Moreover, we did not detect any menaquinone in the livers of these infants in our study. The prophylaxis applied to the other infants was very efficient. Hepatic vitamin K1 concentrations, obtained < 24 h after administration, were very high (62.8-93.5 micrograms/g). Vitamin K1-epoxide concentrations were high, which proved the efficiency of the vitamin K cycle. In contrast, the decrease in vitamin K1 concentrations was also very rapid, since the median value after 48 h was 8.4 micrograms/g and only 2.9 micrograms/g 5 days after administration. However, hepatic total storage after 5 days in one infant with vitamin K1 supplementation was much higher (112 micrograms) than in infants who had not received supplementation. In conclusion, hepatic phylloquinone storage at birth was poor (< 1 microgram). The newborn infant might be in a situation of potential deficiency. After prophylactic oral administration of phylloquinone, uptake by the liver was quite satisfactory, but concentrations dropped quickly. However, phylloquinone hepatic storage remained elevated (112 micrograms) after 5 days.

Administration, Oral↗
PubMed1992

Three electrophoretic techniques comparison for des-gamma-carboxyprothrombin detection.

Des-gamma-carboxyprothrombin (DCP) is a marker that appears in the blood when modifications of vitamin K-dependent proteins carboxylation cycle occur. About 280 human plasma samples of diverse origins were tested by three different electrophoretic techniques for the evaluation of DCP: rocket immunoelectrophoresis (RIE) before and after barium carbonate adsorption, crossed affinoimmunoelectrophoresis (CAIE) and polyacrylamide gel electrophoresis in presence of calcium lactate followed by immunoblotting (PAGE-blot). A good correlation was found between CAIE and PAGE-blot in the CAIE detection limit, but not between RIE and the two other techniques. PAGE-blot was more sensitive than RIE and CAIE and allowed reliable quantification of abnormal prothrombin in plasma.

Adsorption↗
PubMed1992

Hepatic concentration of vitamin K active compounds after application of phylloquinone to chickens on a vitamin K deficient or adequate diet.

Liver and serum concentrations of vitamin K active compounds were measured in two groups of (deficient and normal) broilers after administration of phylloquinone 1 mg/kg. Assays were performed by HPLC after extraction and purification of these compounds. The only menaquinone found in the chicken was menaquinone-4. In the deficient group, the chickens exhibited hepatic concentrations of vitamin K1, vitamin K1 epoxide and menaquinone-4 markedly lower than those of the control group. After administration of phylloquinone, vitamin K and vitamin K epoxide levels fell sharply. There is no hepatic storage of vitamin K comparable to that of vitamin A. However, while menaquinone levels were found to be stable in the control group, they rose significantly in the deficient group after vitamin K injection. The question is: is there a transformation of vitamin K into menaquinone and/or is there a preferential utilization of one of the vitamin K active compounds?

Animals↗
PubMed1991

Des-gamma-carboxyprothrombin detection by immunoblotting after polyacrylamide gel affinoelectrophoresis in human plasmas.

In the absence of vitamin K or in the presence of the vitamin K antagonists, abnormal nonfunctional forms of prothrombin circulate in the blood. A reliable and reproducible technique, derived from traditional crossed affinoimmunoelectrophoresis in presence of calcium lactate, was developed and optimized. The technique is based on nondenaturing polyacrylamide gel affinoelectrophoresis, with calcium lactate, of plasma samples, followed by immunoblotting with rabbit anti-human prothrombin serum and detection with an anti-rabbit immunoglobulin peroxidase conjugate. Depending on the plasmas, one or two bands were visualized and quantified by densitometry of the immunoblots. The technique was able to detect abnormal des-gamma-carboxylated prothrombins at concentration of 0.1 microgram/mL.

Adsorption↗
PubMed1991

Impairment of gamma carboxylation of circulating osteocalcin (bone gla protein) in elderly women.

Osteocalcin, also called bone gla protein, is a unique noncollagenous protein of the extracellular matrix of bone that circulates in blood. Oseteocalcin contains three residues of the vitamin K-dependent gamma-carboxyglutamic acid (gla) responsible for the affinity of osteocalcin for bone mineral. In animals treated with the vitamin K antagonist warfarin, the osteocalcin content of bone is markedly reduced and the fraction of osteocalcin released into the circulation is increased. Most studies have shown that osteocalcin increases with aging in women, reflecting an increase in bone turnover, especially after the menopause. To determine if this increase in osteocalcin could be associated with impaired carboxylation, we measured total and noncarboxylated osteocalcin in the serum of 72 women of various ages: 22 premenopausal (31 +/- 7 years old), 20 early postmenopausal (54 +/- 3 years), and 30 elderly women (85 +/- 8 years). As previously reported, total serum osteocalcin was significantly increased in early postmenopausal and elderly women. Noncarboxylated serum osteocalcin was slightly increased in early postmenopausal women (0.95 +/- 0.4 versus 0.65 +/- 0.5 ng/ml in premenopausal women), markedly elevated in elderly women (1.59 +/- 1.1 ng/ml, p less than 0.001), and correlated with age (r = 0.47, p less than 0.001). Elderly women had values of the same magnitude as in 10 patients on chronic warfarin therapy (1.94 +/- 1.1 ng/ml). As a consequence, the increase in carboxylated serum osteocalcin was significant in early postmenopausal women but not in elderly women. Serum levels of vitamin K1 and of menaquinones 6, 7, and 8 were measured in some of the young and elderly women.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

Placental transfer of vitamin K1 and its implications in fetal hemostasis.

Vitamin K status was evaluated using coagulation studies and/or vitamin K1 assays in a total of 53 normal fetuses and 47 neonates. Second trimester fetal blood samples were obtained for prenatal diagnosis under ultrasound guidance. Endogenous vitamin K1 concentrations (determined by high performance liquid chromatography) were substantially lower than maternal levels. The mean maternal-fetal gradient was 14-fold at mid trimester and 18-fold at birth. Despite low vitamin K levels, descarboxy prothrombin, detected by a staphylocoagulase assay, was elevated in only a single fetus and a single neonate. After maternal oral supplementation with vitamin K1, cord vitamin K1 levels were boosted 30-fold at mid trimester and 60-fold at term, demonstrating placental transfer. However, these levels were substantially lower than corresponding supplemented maternal levels. Despite elevated vitamin K1 concentrations, supplemented fetuses and neonates showed no increase in total or coagulant prothrombin activity. These results suggest that the low prothrombin levels found during intrauterine life are not due to vitamin K deficiency.

Female↗
PubMed1987

Specificity of increased des-gamma-carboxyprothrombin in hepatocellular carcinoma after vitamin K1 injection.

The des-gamma-carboxyprothrombin (DCP) level was found to be increased in the majority of hepatocellular carcinomas (HCC). This increase has to be distinguished from an increased DCP level linked to a vitamin K deficiency. We studied the evolution of increased DCP level in 6 patients with histologically proven HCC and in 10 without HCC after slow injection of 20 mg of vitamin K1. The DCP assays performed subsequent to the vitamin K1 injection showed: first, a durable normalisation of the DCP level in the patients without HCC, suggesting that the increased DCP was linked, in them, to an underlying vitamin K deficiency; second, a transitory decrease followed by a return to the abnormal level in the patients with HCC. We can conclude that an increased DCP level which persists following vitamin K1 injection is specific for HCC. The minimal delay for the DCP assay after vitamin K1 injection seems to be 15 days.

Biomarkers↗
PubMed1987

Variations of phylloquinone concentration in human milk at various stages of lactation and in cow's milk at various seasons.

An improved high-performance liquid chromatographic method was used to measure phylloquinone concentrations in human and cow's milk. Concentrations in human milk obtained serially from 10 mothers 3, 8, and 21 days after delivery were found to increase during the course of lactation. No correlation was found between phylloquinone concentration and lipids but a significant negative correlation was observed between phylloquinone and cholesterol concentrations. Determinations in cow's milk showed increased levels during the summer months. Also, levels in cow's milk were significantly higher than in human milk. Notwithstanding marked individual variations in human milk, phylloquinone concentrations in cow's milk always proved higher than in human milk. Results prompt the necessity of protecting breast-fed infants by applying relevant prophylactics measures.

Adult↗
PubMed1982

Determination of rifampicin, desacetylrifampicin, isoniazid and acetylisoniazid by high-performance liquid chromatography: application to human serum extracts, polymorphonucleocytes and alveolar macrophages.

A method for the determination of rifampicin, desacetylrifampicin, isoniazid, and acetylisoniazid by high-performance liquid chromatography and using the same extract of the same sample is reported. After protein precipitation and extraction of these antituberculous drugs, two reversed-phase chromatographies were necessary. The technique was applied to serum extracts, polymorphonucleocytes and alveolar macrophages from patients treated for tuberculosis.

Chromatography, High Pressure Liquid↗
PubMedDate not supplied

Study of the pharmacokinetics of mitomycin C in humans during intraperitoneal chemohyperthermia with special mention of the concentration in local tissues.

The aim of this work is to estimate the 24-hour distribution and elimination of mitomycin C (MMC) during and after intraperitoneal chemohyperthermia (IPCH) in 18 patients (13 gastric adenocarcinoma, 3 pancreatic adenocarcinoma, 2 malignant mesothelioma) who received 60 mg MMC during 90-120 min in 6 liters of heating solution HS; (42 degrees C) or HS flowing at 0.4 liters/min in a closed circuit. MMC assay in the serum, urine, HS and in local biopsies were performed by high performance liquid chromatography. The amount of MMC in HS decreased by 54.1 +/- 13.6% during IPCH. The maximum MMC levels in serum reached 0.4 +/- 0.18 mg/l 45 min after the start of IPCH, then rapidly decreased. Only 1.77 +/- 0.93 mg were recovered in urine in 24 h. These data are consistent with a large and rapid absorption, mostly in local tissue, demonstrated by the level in 7 post-IPCH biopsies (8.3 +/- 7.6 mg/kg).

Absorption↗