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Biomedical subjects

P Burnat

Publications and source records attributed to P Burnat.

17 recordsLinked to original sources
PubMed2000

High-performance liquid chromatographic determination of cotinine in urine in isocratic mode.

A simple procedure for the determination of cotinine, major metabolite of nicotine in urine, is described. The assay involved a liquid-liquid extraction with dichloromethane in alkaline environment. The extract was dried at ambient temperature under a gentle stream of nitrogen. The residue was dissolved in 300 microl of mobile phase and 30 microl aliquot was injected via an automatic sampler into the liquid chromatograph and eluted with the mobile phase (10-9%, v/v methanol and acetonitrile, respectively in potassium dihydrogenphosphate buffer adjusted to pH 3.4) at a flow rate of 1 ml/min on a C8 Symmetry cartridge column (5 microm, 150 mm x 3.9 mm, Waters) at 25 degrees C. The eluate was detected at 260 nm. Internal standard was 2-phenylimidazole. Sensitive and specific, this technique was performed to test urine of diabetic patients (smokers and non-smokers) admitted in an endocrinology service. Urinary cotinine seems to be a better marker of smoking status than thiocyanates.

Calibration↗
PubMed1998

[Hereditary xanthinuria, rare cause of hypo-uric acidemia. 2 cases].

BACKGROUND: Hypouricemia can be observed in uncommon situations as in our two patients with hereditary xanthinuria. CASE REPORTS: In the first case, hereditary xanthinuria was discovered in a 36-year-old man when routine tests revealed hypouricemia. In the second case, a 76-year-old woman, hypouricemia was also a fortuitous discovery. She had major xanthinuria and a radiotranslucid lithiasis in the right kidney. DISCUSSION: Hereditary xanthinuria is characterized by hypouricemia, low urinary urate excretion and increased concentration of xanthine and to a lesser extent hypoxanthine. The disease results from a defect in xanthine oxidase and is considered to be transmitted by autosomal recessive heredity. This rare metabolic disorder is more often asymptomatic and detected by routine chemistry. Development of xanthine lithiasis is directly related to the low solubility of xanthine and is the main complication of the disease, occurring in 30-40% of patients. There is no effective treatment and the only useful measure is to prevent xanthine urolithiasis by maintaining urinary output above 2 l/day.

Adult↗
PubMed1998

High-performance liquid chromatographic determination of modafinil and its two metabolites in human plasma using solid-phase extraction.

A simple procedure for the simultaneous determination of modafinil, its acid and sulfone metabolites in plasma is described. The assay involved an extraction of the drug, metabolites and internal standard from plasma with a solid-phase extraction using C18 cartridges. These compounds were eluted by methanol. The extract was evaporated to dryness at 40 degrees C under a gentle stream of nitrogen. The residue was redissolved in 250 microl of mobile-phase and a 30 microl aliquot was injected via an automatic sampler into the liquid chromatograph and eluted with the mobile-phase (26%, v/v acetonitrile in 0.05 M orthophosphoric acid buffer adjusted to pH 2.6) at a flow-rate of 1.1 ml/min on a C8 Symmetry cartridge column (5 microm, 150 mm x 3.9 mm, Waters) at 25 degrees C. The eluate was detected at 225 nm. Intra-day coefficients of variation ranged from 1.0 to 2.9% and inter-day coefficients from 0.9 to 6.1%. The limits of detection and quantitation of the assay were 0.01 microg/ml and 0.10 microg/ml respectively.

Administration, Oral↗
PubMed1998

[Cholinesterases].

OBJECTIVE: To review current data on butyrylcholinesterase. DATA SOURCES: Search through Medline data bases of articles in French or English. STUDY SELECTION: Original articles and case reports were selected. Letters to editor were excluded. DATA EXTRACTION: The articles were analyzed in order to obtain current data on biochemical structure, action, major pathological variations, especially with regard to the recent informations obtained by molecular biology concerning the identification of genetic variants. DATA SYNTHESIS: Butyrylcholinesterase must be differentiated from acetylcholinesterase, which cannot hydrolyse succinylcholine. The physiological action of butyrylcholinesterase remains unknown, although it can hydrolyse many drugs. Excluding genetical mutations, several physiopathological situations alter butyryl-cholinesterase activity. Butyrylcholinesterase activity assessment does not allow the diagnosis of genetic variants. Whatever the origin, only deficits of more than 50% modify significantly the metabolism of succinylcholine or mivacurium. The diagnosis of a prolonged neuromuscular blockade is obtained with systematic monitoring of the neuromuscular function in case of administration of mivacurium or succinylcholine. Mivacurium should only be re-injected when one response at train of four is obtained. In case of prolonged neuromuscular blockade, the anticholinesterasic agent should not be administered when no response at train of four is obtained. The biochemical methods using inhibitors (dibucaine, fluoride) of the butyrylcholinesterase and a familial study lead to the diagnosis in most cases because the atypical and fluoride variants are the most frequent. When results are doubtful, genetic molecular methods with the use of PCR and restriction enzymes allow a rapid diagnosis.

Acetylcholinesterase↗
PubMed1998

Prolonged mivacurium neuromuscular block in children.

The authors report two cases of prolonged neuromuscular block after administration of mivacurium in children with previously undiagnosed plasma cholinesterase deficiency related to homozygous atypical genotype. Their anaesthetic management is described as well as determination of the phenotype of both children and their family.

Anesthesia Recovery Period↗
PubMed1996

[Ecstasy: psychostimulant, hallucinogen and toxic substance].

MDMA or 3,4-methylenedioxymethamphetamine, more commonly called "ecstasy", is a drug classified as a stupefiant and increasingly used by young people for its stimulant and hallucinogen effects. This popular designer drug is often used in techno or rave parties and perceived by users as relatively harmless. It has however been associated with disorders of thermoregulation and has been the cause of several deaths. In addition, the drug has been shown to destroy serotonin receptors in the brain in the monkey and leads to serious physchiatric disorders and liver damage in man.

Animals↗
PubMed1987

[Phenotype of plasma cholinesterase in prolonged apnea and sensitivity to succinylcholine].

90% of the injected dose of succinylcholine is hydrolysed by serum cholinesterase (E.C.3.I.I.8) Abnormal variants of serum cholinesterase lead to prolonged apnea. This report presents the results of 62 serum cholinesterase phenotyping including 12 cases of prolonged apneas. One clinical case of prolonged apnea in a patient homozygous for the atypical cholinesterase gene is presented with a study of his genealogy. The phenotypes were established on the basis of dibucaïne, fluorure, chloride and propranolol differential inhibition. The frequency and significance of the various phenotypes is discussed.

Anesthesia, General↗
PubMed1982

[Multiple molecular forms of human plasma butyrylcholinesterase. II.-Study of the C1, C3 and C4 components by means of affinity electrophoresis (author's transl)].

Affinity electrophoresis has been applied to the analysis of the multiple molecular forms of human plasma cholinesterase allozyme U. A water-soluble p-amino-substituted-phenyltrimethylammonium polyacrylamide was synthetized by copolymerization of an unsaturated derivative of the ligand with acrylamide, and entrapped at various concentrations within the matrix of separating gels. Electrophoresis was carried out in these gels, and the relative mobility of the molecular forms of the enzyme was decreased. From the variation of mobility (Rm) as a function of immobilized ligand concentrations, the apparent dissociation constants of monomer (C1), dimer (C3) and tetramer (C4) of phenotype U were calculated. The decrease in mobility was reversed by addition of non-immobilized competitive ligands (N-methylpyridinium and N-methylacridinium). The appearance of the slopes of Rmi-1 vs. concentration does not give sufficient information for determination of the number of anionic binding sites of C4, but the slight curvature of the plots suggests that bivalent or higher interactions occur when the concentration is sufficiently high. For all three size isomers from a critical ligand concentration, a second zone, named B, appears and intensifies rapidly at the expense of the first zone (A) as the immobilized ligand concentration increases. Among several possible explanations of this phenomenon, it is proposed that the ligand induces a conformational isomerization of the enzymes with a change in affinity (KD,B less than KD,A) and that the interconversion process between the two states B in equilibrium A is slow compared with the ligand-association equilibrium dissociation steps.

Acridines↗
PubMedDate not supplied

[Blood levels of homocysteine by high pressure liquid chromatography and comparison with two other techniques].

Cardio-vascular diseases are the most common cause of death in industrialized countries. A new marker has emerged among offending risk factors in the past few years: homocysteine. This sulphured amino-acid is an important intermediate in transsulphuration and remethylation reactions of methionine's metabolism. We proposed to evaluate a home made method of determination for this parameter by high performance liquid chromatography (HPLC) and to compare it to fluorescence polarization immunoassay technique (FPIA) and to gaz phase chromatography (CG-SM). This method associated with good sensibility and precision remain much less expensive than FPIA technique.

Acetylcysteine↗
PubMedDate not supplied

[Biological monitoring of chronic hemodialysis].

Patients suffering from acute renal failure must undergo dialysis to substitute for the kidney's excretory function. Dialysis is a means of exchange between two solutions: blood and a liquid known as dialysate, across a semi-permeable membrane. This membrane permits the passage of water and aqueous solutions of low molecular weight but not that of the aqueous solutions of high molecular weight such as proteins. Dialysed patients are biologically monitored to prevent the various complications arising from blood dialysis, to check the efficacy of the treatment as well as to reduce the risk of morbidity and mortality. Because of the multiple and complex nature of renal functions, biological monitoring of a dialysis patients presents many, often inter-related facets. In addition to the complications inherent in dialysis itself, the dialysed patient is exposed to other causes of mortality or morbidity such as nutritional, hematologic, cardiovascular and infectious problems. Clinicians is confronted by other complications, albeit less common and easier to control, in the form of osteoarticular troubles or even aluminium poisoning. Lastly, biological assessment of the efficacy of purifying processing depends principally on calculating the dose of dialysate and the ureic index of subtraction which, in turn, requires the measurement of uremia.

Acid-Base Equilibrium↗