[Influence of temperature and delayed centrifugation: stability studies of 28 analytes currently analysed]. / Influence de la température et du délai avant centrifugation sur la stabilité de 28 paramètres de détermination courante en biochimie.

A large amount of off-site blood sampling are analysed in our laboratory with a variable conveying time of up to 7 hours. Fifteen healthy volunteers were included in this study. The aim was to evaluate the stability of current analytes in regard to the temperature and the time before centrifugation. Whole blood obtained by venipuncture was collected into collector tubes respectively with heparinate for plasma recovery and on dry tube for TSH determination. All the analytes, except potassium and phosphate showed a good stability at +22 degrees C, with a centrifugation delay of up to 7 hours. A sample storage at +4 degrees C didn't show any better stability for potassium but allowed a significant improvement of phosphate stability. Sample conservation at +22 degrees C can be considered as well suited for current biochemistry determinations. However, in specific calcium and phosphate metabolism investigations, samples preservation at +4 degrees C can be justified. Finally, in potassium assay, regardless of the chosen conservation temperature, centrifugation should occur within 2 hours of sampling.

Comparative diagnostic performance of two commercial rapid tests for malaria in a non-endemic area.

In the study reported here, the diagnostic performance of two new rapid tests for the diagnosis of malaria was evaluated in symptomatic patients in a non-endemic area. Of 557 consecutive patients, 109 (19.6%) had documented malaria. For the NOW ICT MALARIA P.f./P.v. (Binax, Portland, ME, USA) and OptiMAL IT (Diamed, Cressier, Switzerland) tests, respectively, sensitivity values were 96.3% and 79.8% (P-value, 0.0001), and specificity values were 98.8% and 98.4%. The NOW ICT test did not detect two of 80 Plasmodium falciparum infections, and it generated false-positive results for five patients. The OptiMAL IT test failed to detect ten of the P. falciparum infections, and it generated seven false-positive results. The results suggest that these rapid diagnostic tests for malaria may be useful, but they cannot replace microscopic examination of blood films.

Simultaneous determination of pyrimethamine and sulphadoxine in human plasma by high-performance liquid chromatography after automated liquid-solid extraction.

A high-performance liquid chromatographic method with ultraviolet detection is described for the simultaneous measurement of pyrimethamine and sulphadoxine in human plasma. After an automated liquid-solid extraction on a C8 cartridge, the compounds are separated on a C18 column by isocratic elution; the mobile phase is methanol-acetonitrile-water (10:25:65, v/v/v) with triethylamine (1%) and adjusted to pH 5.6 with phosphoric acid. The eluent is monitored with an ultraviolet detector at 240 nm. The limit of quantification was 10 ng/ml for pyrimethamine and 22 microg/ml for sulphadoxine. No chromatographic interferences can be detected from endogenous compounds, other anti-malarial drugs or major drugs used for the treatment of children. Sulphadimethoxine is used as an internal standard. The method is accurate and precision is good with relative standard deviations lower than 6%. The chromatographic procedure takes 11 min. The method is comparatively rapid, simple, sensitive and can be used for therapeutic drug monitoring, clinical and pharmacokinetic studies.

Chloroquine self-treatment and clinical outcome of cerebral malaria in children.

Chloroquine is widely used as self-medication for presumptive treatment of malaria despite the existence of parasite resistance to the drug. Recent studies suggest that tumour necrosis factor-alpha (TNF-alpha) overproduction probably has a causal association with poor outcome in cerebral malaria. In addition, chloroquine has been shown to have inhibitory action on TNF-alpha synthesis. The present study aimed at evaluating chloroquine/TNF-alpha interaction in 90 children hospitalized for severe malaria in a malaria-endemic zone. TNF-alpha and chloroquine varied in the same range on admission, but there was an inverse correlation between the two: the higher the chloroquine level, the lower the TNF-alpha level. Parasite resistance to chloroquine in vitro was high. The clinical course in the patients was uneventful, save for two fatal cases and one survivor with neurological sequela. The above data suggest beneficial effects of chloroquine self-medication with respect to anti-TNF-alpha action. Rational use of this tool should be encouraged.

New solid-phase extraction for an improved high-performance liquid chromatographic procedure for the quantitation of halofantrine and monodesbutylhalofantrine in blood or plasma.

A rapid, accurate, and sensitive high-performance liquid chromatographic (HPLC) method, with fluorimetric detection, for the simultaneous measurement of halofantrine and desbutylhalofantrine in human plasma or whole blood is described. Sample preparation involved protein precipitation, followed by an efficient solid-phase extraction on a C8 cartridge. Analytes were isolated from 1 ml of the biological fluids and recovered by a 2% acetic acid in ethyl acetate solution. Chromatographic separation was carried out on a LiChrospher 60 RP select B, C8 bonded phase (5 microns particle size, 25 cm x 4 mm I.D.) using a mobile phase of water-acetonitrile (35:65, v/v) containing triethylamine (1%) and adjusted to pH 4 with orthophosphoric acid. The total run time was 14 min. Relative standard deviations of the intra-and inter-assay precisions were less than 5.9%. Assumption of linearity was investigated by studying the y-residuals and by ANOVA (analysis of variance). Because of the wide range of calibration (0.1 to 2.0 microgram/ml) variances were non-homogeneous (Hartley's test) and the weighted regression line was computed in order to allow pharmacokinetic studies. Accuracy was tested using a t-statistic. Limits of decision, detection and quantification were realized from an analysis of the blanks. Application of the method to clinical specimens was demonstrated.

Determination of doxycycline in human plasma and urine samples by high performance liquid chromatography. Application for drug monitoring in malaria chemoprophylaxis.

A reverse-phase high performance liquid chromatographic method with ultraviolet detection is described for the measurement of doxycycline in human plasma and urine. After liquid-solid extraction on a Bond Elut C18 cartridge, doxycycline and demeclocycline (internal standard) are separated on a Novapak C18 column by isocratic elution. The mobile phase consists of acetonitrile-oxalate buffer, pH 2.3 (25:75; v/v). The eluent is monitored with an ultraviolet detector at 355 nm. The lower limit of quantification in plasma is close to 25 ng/ml. No chromatographic interference can be detected from endogenous compounds, tetracycline group antibiotics or antimalarial drugs. The method is accurate and precision is good with inter- and intra-assay relative standard deviations lower than 6.7%. The chromatographic procedure takes 8 minutes and can be used for therapeutic drug monitoring, clinical and pharmacokinetic studies.

Simultaneous determination of chloroquine, proguanil and their metabolites in human biological fluids by high-performance liquid chromatography.

A reversed-phase ion-pair high-performance liquid chromatographic method with ultraviolet detection is described for the simultaneous measurement of chloroquine, proguanil and their major metabolites in human plasma, erythrocytes and urine. After a liquid-solid extraction on a Bond Elut C8 cartridge, the compounds are separated on a C8 Lichrospher 60 RP select B column by isocratic elution; the mobile phase is water-acetonitrile-methanol (78:28:4, v/v/v) with 0.5 M ammonium formate and 0.075 M perchloric acid. The eluent is monitored with an ultraviolet detector at 254 nm. The lower limits of quantification in plasma are near 6.0 ng ml-1 for chloroquine and near 9.0 ng ml-1 for proguanil. No chromatographic interference can be detected from endogenous compounds or from other antimalarial drugs. The method is accurate and precision is good with inter- and intra-assay relative standard deviations lower than 6.8% for plasma samples. N-(2-6 dichlorobenzylidene amino)guanidine is used as an internal standard. The chromatographic procedure takes 35 min and can be used for therapeutic drug monitoring and clinical studies.

Simultaneous determination of chloroquine and quinine in human biological fluids by high-performance liquid chromatography.

A high-performance liquid chromatographic method with fluorescence detection is described for the simultaneous measurement of quinine, chloroquine and mono- and bidesethylchloroquine in human plasma, erythrocytes and urine. After a liquid-solid extraction on a Bond Elut C8 cartridge, the compounds are separated on an Inertsil silica column by gradient elution; the mobile phase is a mixture of acetonitrile and methanol-25% ammonia solution (92.7:7.5, v/v). The eluent was monitored with a fluorescence detector (excitation wavelength 325 nm and emission wavelength 375 nm). The limit of detection was ca. 5 ng/ml for chloroquine and ca. 23 ng/ml for quinine. No chromatographic interferences could be detected from endogenous compounds or other antimalarial drugs. The method is accurate with inter- and intra-assay coefficients of variation lower than 7%. Hydroxychloroquine is used as an internal standard because of its structural similarity to chloroquine. The procedure requires 30 min and can be used for therapeutic drug monitoring.

[Simple methods of chloroquine determination in urine and their adaptation in the field]. / Les méthodes simples de dosage de la chloroquine dans les urines et leur adaptation sur le terrain.

Field malaria studies require often the on site detection of chloroquine in urine for monitoring chemoprophylaxis and treatment compliance, investigating drug-use patterns and screening prospective subjects for in vitro and in vivo chemosensitivity tests. The field adapted methods are described, analytical characteristics are compared and different approaches to field adapted assay of chloroquine are discussed.

[Diagnosis of muscular intolerance during exercise caused by enzyme deficiency in adults]. / Diagnostic d'une intolérance musculaire à l'exercice par déficit enzymatique chez l'adulte.

The exertional muscle pain syndrome in adults is expressed by recurrent episodes of pain and/or episodes of acute rhabdomyolysis, sometimes with transient myoglobinuria or even acute renal failure. The enzymatic origin of this syndrome is suggested by a familial history, by its usual onset during childhood or adolescence, and by its recurrent attacks usually, but not exclusively, caused by exercise. The aetiological diagnosis, suggested by the clinical context and some dynamic tests, is almost always based on good histological and biochemical examinations of the muscle biopsy.

[Quality of sedation and neurologic evaluation following surgery of the posterior cranial fossa: the importance of propofol]. / Qualité de la sédation et évaluation neurologique après chirurgie de la fosse cérébrale postérieure: intérêt du propofol.

Following cerebral posterior fossa surgery, 23 patients were admitted in Intensive Care Unit for postoperative mechanical ventilation. Mean age was 45 +/- 16 years. Mean duration of surgical procedure was 09 h 20 min +/- 04 h 45 min. Heart rate, blood pressure, coma Glasgow scale, pupil reaction, respiratory pattern were recorded throughout the study. Following recovery from anaesthesia sedation was initiated by an intravenous bolus injection of propofol 2 mg.kg-1 followed by a continuous infusion starting at 1 mg.kg-1.h-1. The infusion rate was adjusted thereafter to ensure that the patient was sedated (Glasgow coma scale less than or equal to 6), unable to react to tracheal suction, well adapted to mechanical ventilation with a cardiovascular stability. Mean duration of sedation was 27 h 45 min +/- 04 h 45 min. Mean infusion rate of 3.81 mg.kg-1.h-1 allowed good sedation in 22 patients. There were no clinical changes in arterial pressure and heart rate. Propofol infusion was stopped transiently to assess neurologic status at 18 h +/- 02 h 45, 33 h 45 +/- 08 h 15, 49 h 10 +/- 16 h 50 after sedation onset. During these interruptions, the speed of recovery was assessed and arterial blood samples taken simultaneously. When the infusion was discontinued, adequate recovery was obtained in 48 +/- 26 min for 17 patients of 23, 64 +/- 58 min for 7 of 12, 70 +/- 65 min for 3 of 3.(ABSTRACT TRUNCATED AT 250 WORDS)

[Malaria: chloroquine resistance]. / Paludisme: la résistance a la chloroquine.

Chloroquine remains the most commonly antimalaric drug utilized all around the world (340 t in 1988). Its efficiency is linked to its action on the digestive vacuole of plasmodium. Since 1957, the areas of resistance are spreading over of an alarming way, striking all continents. 3,000 cases of malaria are imported in France each year, and 90% of the strains tested in vitro by incorporating tritium hypoxanthine are resistant to chloroquine. The resistant parasites are able to exclude chloroquine from their cytoplasm and produce in great number two genes to synthetize a glycoprotein, probable agent of cellular exclusion of the antimalaric drug. Despite of it, to prescribe chloroquine in prophylaxis remains indispensable, because the risk of severe malaria due to some sensitive strains of Plasmodium falciparum.