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Biomedical subjects

F Guyon

Publications and source records attributed to F Guyon.

At least 19 recordsLinked to original sources
PubMed2001

Speciation of arsenic and selenium compounds by ion-pair reversed-phase chromatography with electrothermic atomic absorption spectrometry. Application of experimental design for chromatographic optimisation.

An off-line system is proposed consisting of ion-pair reversed-phase liquid chromatography, collections of fractions at the outflow of the column and furnace atomic absorption spectrometry. The so-called system allowed determination of both arsenic and selenium species mainly found in the environment and in mammals (arsenite, arsenate, monomethylarsonate, dimethylarsinate, selenite, selenate, selenocystamine, selenocystine, selenomethionine and selenoethionine). In order to study the retention behaviour of these compounds and to estimate the optimal conditions for the chromatographic separation, central composite designs were used to evaluate the influence of the eluent parameters such as pH, tetrabutylammonium phosphate (TBA) concentration and sodium hydrogenphosphate amounts. The retention factors of each species and the selectivity were established as response criteria. Response surfaces and isoresponse curves were drawn from the mathematical models and enabled one to determine the optimal conditions and to visualise the method robustness. The predicted optimal zone was situated at pH 5.5-6.5, 4.0 mM Na2HPO4 and 3.0-4.0 mM TBA. Regression models suggested linearity for the studied compounds in the range 25-200 microg selenium and arsenic per litre investigated.

Arsenic↗
PubMed2001

XAS applied to pharmaceuticals: drug administration and bioavailability.

We present selected XAS applications, focused towards practical hospital questions of drug administration and bioavailability, where the technique is driven up to its limits of sensitivity. i) XAS was used to study the interactions between the components of parenteral nutrition solutions, in particular zinc and aminoacids, possibly modifying their bioavailability. ii) We studied by EXAFS a series of binary and ternary copper-aminoacid complexes, in view of the development of an efficient oral drug against copper deficiencies in Menkes disease. iii) EXAFS and XANES analysis allowed us to characterise the solution form of a new arsenic containing drug against leukaemia. In parallel to the XAS measurements, we analysed trace elements levels along patients' hairs, using X-ray fluorescence excited by synchrotron radiation. The measurements along the hair allow for a monitoring of essential trace elements during therapy.

Arsenic Trioxide↗
PubMed2001

Stability of stored methacholine solutions: study of hydrolysis kinetic by IP-LC.

Methacholine chloride is a powerful cholinergic bronchoconstrictor agent used during bronchial airway hyper-responsiveness diagnosis. Methacholine is susceptible to hydrolysis in aqueous solutions in acetic acid and beta-methylcholine. In the present work, kinetics of hydrolysis with different solvents (water and phosphate-buffered saline (PBS) pH 7.4) at different temperatures have been studied using a newly developed high-performance liquid chromatography. At 4 degrees C, kinetic determination of hydrolysis in methacholine chloride solutions (50 mg/ml) shows no hydrolysis in either aqueous or phosphate-buffered solutions over a 40-day period. At 30 degrees C, concentration of unbuffered methacholine chloride solutions remained unchanged, but buffered methacholine chloride solutions have degradation up to 5.5% over a 40-day period. At 40 degrees C, concentration of unbuffered methacholine chloride has degradation up to 5% and buffered methacholine chloride solutions have degradation up to 10% over a 40-day period. Methacholine chloride solutions are susceptibly to be used in hospital pharmacy at different concentrations. We have studied pH and osmolality for methacholine solutions prepared with different diluents potentially used in hospital pharmacies, i.e. deionized water, 0.9% NaCl and PBS pH 7.4. We have demonstrated that methacholine solutions prepared with deionized water at 50 mg/ml and diluted with PBS pH 7.4 from 5 to 40 mg/ml are isoosmotic and potentially available for inhalation tests to measure non-specific bronchial hyper-responsiveness.

Bronchoconstrictor Agents↗
PubMed2001

Application of central composite designs for optimisation of the chromatographic separation of monomethylarsonate and dimethylarsinate and of selenomethionine and selenite by ion-pair chromatography coupled with plasma mass spectrometric detection.

Central composite designs (CCDs) were used in the study of the ion-pair chromatographic separation of arsenic and selenium species in tap water: monomethylarsonate, dimethylarsinate, selenomethionine and selenite. The ternary eluent consisted of tetrabutylammonium phosphate (TBA), sodium hydrogenphosphate (Na2HPO4) and 1% acetonitrile. CCD allowed the investigation of the influence of the eluent parameters, which varied from 0.5 to 4.2 mmol l-1 Na2HPO4, 0.5 to 4.2 mmol l-1 TBA and pH 4.9 to 8.2, on the capacity factors (k') of arsenic and selenium compounds. Furthermore, another mathematical model that permitted the variation of the chromatographic selectivity of species, computed from their retention data to be followed, was investigated. This showed the ability to locate the optimum conditions within the experimental design, so that arsenic and selenium species could be simultaneously quantified with good efficiency and resolution. A comparison between the predicted and the experimental response values was made in order to assess the prediction quality of the model. Response surfaces and isoresponse curves obtained from the mathematical models allowed the determination of the optimum chromatographic conditions and the robustness of the method. The predicted optimum zone allowing satisfactory determination of both arsenic and selenium compounds was pH 5.5-6.5, 2.5 mmol l-1 Na2HPO4 and 3.0-4.0 mmol l-1 TBA.

Journal Article↗
PubMed2000

On-line reversed-phase liquid chromatography hydride generation emission spectrometry: speciation of arsenic in urine of patients intravenously treated with As2O3.

Hydride generation inductively coupled plasma-atomic emission spectrometry (HG ICP-AES) was used as a continuous detection system for the determination of arsenic in the eluate from a high-performance liquid chromatographic (HPLC) system. Four arsenic species [arsenite As(III), arsenate As(V), monomethylarsonate (MMA), and dimethylarsinate (DMA)] present in the urine samples of patients treated intravenously with arsenite, were analyzed separately by HPLC-HG-ICP-AES using a non-polar C18 column. This analytical method allowed the sensitive determination of the arsenic species in the submicrogram per liter range. Urine samples collected on different days after arsenite administration were found to contain arsenite predominantly--monomethylarsonate and dimethylarsinate were also detected.

Arsenic↗
PubMed2000

Permeation liquid membrane metal transport: studies of complex stoichiometries and reactions in Cu(II) extraction with the mixture 22DD-laurate in toluene/phenylhexane

The role of lauric acid (LAH) in the transport of copper(II) through a permeation liquid membrane (PLM) comprising 1,10-didecyldiaza-18-crown-6 (22DD) and lauric acid (ratio 1:1) in 1:1 v/v toluene/phenylhexane has been investigated by determining the stoichiometry of metal extraction and of the metal complex formed in the organic phase by performing 1H NMR and liquid/liquid and liquid/membrane extraction measurements. In the absence of copper(II), the 1H NMR data suggest that there is a strong interaction between the proton of LAH and the nitrogen of the 22DD macrocycle but no interaction between the aliphatic long chains of LAH and 22DD. Thus, in the organic solution, the two compounds are associated as (22DD-H)(+)-LA-, the laurate being away from (22DD-H)+. The signal intensity of the acidic proton was found to decrease when the metal Pb(II) was incorporated by the carrier after its extraction from the aqueous phase. Additionally, liquid/liquid as well as liquid/membrane extraction results reveal that Cu(II) extraction proceeds via the loss of two protons from the organic phase. The Cu(II) is found to be located in the 22DD cavity and the stoichiometry of the complex in the organic phase is (22DD-Cu)(2+)-2LA-. Metal extraction is governed by 22DD and laurate acts only as counteranion. An unexpected feature was observed in the liquid/liquid extraction which was that, at low 22DD and LAH concentrations, the slope for log(Kp) = f(pH) was 2 whereas it was much lower at high carrier concentration. This unexpected result seems to stem from impurities present in 22DD: only 0.1 mol% of impurity can indeed influence the exchange ratio of Cu(II) and H+. This type of anomaly, however, is not found in the normal procedure of liquid/membrane extraction possibly due to the lower carrier/metal molar ratio which is used in the classical PLM conditions.

Journal Article↗
PubMed2000

MappetShow: non-linear visualization for genome data.

The genome mapping projects now produce very dense maps with up to several thousands of markers per chromosome. Besides synteny plays a increasing role in mapping: enrichment of poor maps from the maps of close genomes (in terms of evolution) is a high-reward task. We propose a map viewer adapted to this situation: MappetShow gives a clear view of very dense maps and compares efficiently several maps. MappetShow is based on non-linear viewing and is written in Java. A map description language isolates the software from the data sources. This software was easily used on data coming from as different sources as an Object Request Broker, an Object-Oriented Database, or a flat data stream. MappetShow can be browsed at the URL http:¿www.infobiogen.fr/services/Mappet. More generally we discuss how to use the non-linear viewing concept in molecular biology data visualization.

Chromosome Mapping↗
PubMed2000

[Maternal transport to the Bordeaux University Hospital: a retrospective study of 263 cases (1996-1998)].

OBJECTIVES: To describe a population of high risk pregnancies transported to a regional perinatal care centre (level III) and to analyze the advantages and limitations of the organization of this perinatal care network. METHODS: Retrospective study of 263 patients transported to the University Hospital of Bordeaux between September 1996 and September 1998. RESULTS: Maternal transport mainly came from the Gironde department (53%) and from level I care hospitals (66%). The rate of multiple pregnancies was 17%. Principal indications were preterm labor with or without rupture of fetal membranes (52%) and preeclampsia with or without intrauterine growth restriction (28%). The rate of returns to the referring care centre was 2%. The mean term at delivery was 32 WA. Forty-one percent of patients delivered within 24 hours of transport. The rate of caesarean sections was 55%. There were 303 live births. The mean duration of hospitalization of the neonates was 28 days. The rate of perinatal mortality was 6.2%. Among the 96 pregnancies beyond 32 WA, 17 (6.5%) could have been transported to some level IIb care hospitals, nearby the patient's residence, without changing maternal and neonatal prognosis. Neonatal mortality was not significantly different for maternel transport (18%) or neonatal transport (14%) in the group of premature infants born prior to 31 WA in our study. CONCLUSION: Our organization is currently trying to improve transport management (non-emergency situations, collaboration of level II care hospitals) and to increase the rate of returns to the referring care centres.

Adolescent↗
PubMed1999

The HuGeMap Database: interconnection and visualization of human genome maps.

The HuGeMap database stores the major genetic and physical maps of the human genome. HuGeMap is accessible on the Web at http://www. infobiogen.fr/services/Hugemap and through a CORBA server. A standard genome map data format for the interconnection of genome map databases was defined in collaboration with the EBI. The HuGeMap CORBA server provides this interconnection using the interface definition language IDL. Two graphical user interfaces were developed for the visualization of the HuGeMap data: ZoomMap (http://www.infobiogen.fr/services/zomit/Zoom Map.html) for navigation by zooming and data transformation via magic lenses, and MappetShow (http://www.infobiogen.fr/services/Mappet) for visualizing and comparing maps.

Animals↗
PubMed1999

Detection and modeling of disease susceptibility locus effects: how much can be learned from contrast of populations?

We report the results of our analyses of the GAW11 Problem 2 data set, using information from three different populations. In the first part of the paper, we used classical population genetic tests to compare affected individuals from the different populations, stratifying on the environmental factors. Thanks to existing linkage disequilibrium in one population, we found one of the disease susceptibility loci. In the second part of the paper, we used the marker association segregation chi 2 method to model the role of this disease susceptibility locus in the different populations and draw some inferences regarding the model used at that locus to generate the data.

Chromosome Mapping↗
PubMed1999

Successful treatment of refractory supraventricular tachycardia by repeat intravascular injection of amiodarone in a fetus with hydrops.

We report the case of a fetus with supraventricular tachycardia complicated by congestive heart failure and ascites. After failure of initial transplacental treatment, the injection of amiodarone into the umbilical vein combined with evacuation of ascites achieved conversion to sinus rhythm and restored cardiac function thus allowing pregnancy to go to term. This report suggests that direct fetal therapy by umbilical vein puncture and evacuation of effusions constitutes an effective treatment for supraventricular tachycardias with massive fetal hydrops which do not respond to transplacental treatment.

Adult↗
PubMed1999

A proposal for a standard CORBA interface for genome maps.

MOTIVATION: The scientific community urgently needs to standardize the exchange of biological data. This is helped by the use of a common protocol and the definition of shared data structures. We have based our standardization work on CORBA, a technology that has become a standard in the past years and allows interoperability between distributed objects. RESULTS: We have defined an IDL specification for genome maps and present it to the scientific community. We have implemented CORBA servers based on this IDL to distribute RHdb and HuGeMap maps. The IDL will co-evolve with the needs of the mapping community. AVAILABILITY: The standard IDL for genome maps is available at http:// corba.ebi.ac.uk/RHdb/EUCORBA/MapIDL.htm l. The IORs to browse maps from Infobiogen and EBI are at http://www.infobiogen.fr/services/Hugemap/IOR and http://corba.ebi.ac.uk/RHdb/EUCORBA/IOR CONTACT: manu@infobiogen.fr, tome@ebi.ac.uk

Animals↗
PubMed1998

HuGeMap: a distributed and integrated Human Genome Map database.

The HuGeMap database stores the major genetic and physical maps of the human genome. It is also interconnected with the gene radiation hybrid mapping database RHdb. HuGeMap is accessible through a Web server for interactive browsing at URL http://www.infobiogen. fr/services/Hugemap , as well as through a CORBA server for effective programming. HuGeMap is intended as an attempt to build open, interconnected databases, that is databases that distribute their objects worldwide in compliance with a recognized standard of distribution. Maps can be displayed and compared with a java applet (http://babbage.infobiogen.fr:15000/Mappet/Show. html ) that queries the HuGeMap ORB server as well as the RHdb ORB server at the EBI.

Chromosome Mapping↗
PubMed1997

[Intravenous leiomyomatosis of uterine origin with cardiac extension. A case report and review of the literature].

A case of intravenous leiomyomatosis of the uterus with extension into the heart discovered in a 34-year old patient who suffered from dyspnea is reported. The findings suggest that intravenous leiomyomatosis originates from the smooth muscle component of uterine veins. Only 30 cases of intravenous leiomyomatosis with intracardiac extension have been reported. Two-dimensional echocardiography showed an abnormal mass in the right atrium. Pelvic echography showed an abnormal mass in the pelvis. In case of cardiac involvement, spontaneous prognosis remains poor. The primary goal of surgery is the complete removal of the tumor. Hormonotherapy should also be considered in case of unresectable residual tumor. A long-term follow-up of patients after resection of intravenous leiomyomatosis is needed because recurrences up to 17 years after primary resection have been reported.

Adult↗
PubMed1997

[Endometrial resection in the management of menometrorrhagia refractory to medical treatment].

The authors report the results of 197 endometrectomies and analyse the indications, complications and long-term results. A retrospective analysis was performed at La Conception Hospital. Department of Gynaecology-Obstetrics, Prof Blanc, Marseille, between June 1988 and June 1994. The mean follow up was 53 months. 197 endometrectomies were performed in 186 women during this period. The indication was menometrorrhagia failing to respond to medical therapy. We considered patients to be cured when they no longer suffered from menorrhagia or metrorrhagia and when hormone replacement therapy could be started or continued. The success rate with a follow-up of 7 years was 70%. The failure rate was correlated with the woman's age, hysterometry data and histological results. The complication rate was 2.5%. Endometrectomy appears to be a safe and successful technique for the treatment of menometrorrhagia.

Adult↗
PubMed1996

Comparison between a rapid glycohaemoglobin (HbA1c) immunoassay and other indices of glycaemic control.

The aims of the study were to compare glycohaemoglobin (HbA1c) values measured by DCA (a benchtop analyzer primarily designed for within-clinic rapid HbA1c determination) to a reference HbA1c method and home blood glucose monitoring, and to explore the possibility of an uniform expression of data. A total of 103 blood samples and the corresponding mean capillary glucose values (4.4 +/- 1.2 tests/day) of the preceding 2 months were collected from 34 insulin-dependent diabetic adults. We measured the correlations and agreements using the residual plots method and regression equations between HbA1c measured by DCA and high-pressure liquid chromatography (HPLC), and between DCA and capillary glucose values. A highly significant correlation (r2 = 0.85, P < 0.001) and an acceptable agreement (97% of values within 2 SD of the mean difference of 0.9% +/- 0.4%) was found between DCA and HPLC values. The regression equation calculated on the first half of the cases was: DCA (%) = 0.72 HPLC (%) +1.38. Of DCA values expressed in HPLC terms using this equation 87% fell within a clinically acceptable confidence interval when compared with measured HPLC data. A significant correlation (r2 = 0.40, P < 0.01) was found between DCA and capillary glucose values, and the regression equation was: DCA (%) = 0.34 capillary glucose (mM) +4.44. Of glycaemic levels calculated from DCA values using this formula 82% fell within a clinically acceptable error range when compared with measured glycaemic values. We conclude that the three methods of assessment of diabetes control are well correlated and that it is possible, with a degree of precision acceptable for the clinical setting, to express all data in uniform units, e.g. mM of capillary glucose or percentage of HPLC-HbA1c, though a simple correspondence table based on our transfer equations may be clinically sufficient and more handy.

Adult↗