[Urine Dipstick Screening tests: can they allow to conclude the absence of a urinary tract infection in diabetic hospitalised patients]. / Evaluation d'une pratique professionnelle : la bandelette urinaire permet-elle d'exclure le diagnostic d'infection urinaire chez le patient diabétique adulte hospitalisé ?

UNLABELLED: Asymptomatic urinary tract infections are common in diabetic patients. The aim of this 10 months prospective study is to evaluate urinary dipstick tests versus cytobacteriological examination to conclude the absence of urinary tract infection in diabetic subjects. Each diabetic patient hospitalised for less than 8 hours and for whom it was decided a cytobacteriological examination was included in the study (141 samples). At the same time (and at patient's bedside) a dipstick urinalisys (glucose, leucocytes, nitrite, blood, protein, and ketone) was carried out. Sensitivity, specificity, negative predictive value, post test probability and negative likehood ratio were calculated. RESULTS: the combination of leucocyte zone with nitrite zone (both negative) has a 85,2% sensitivity, avoids 65% of cytobacteriology, but has an odd ratio at 0,20. Those results are improved when the glucose zone (negative test or less than 4 crosses) is taken into account, with a 96,3% sensitivity, 63,4% cytobacteriology avoided and a negative likehood ratio at 0,06. CONCLUSION: The addition of the glucose test to the usual leucocytes and nitrite tests seems to allow one to conclude the absence of urinary tract infection in diabetic patients; this is worth studying with a more extensive sample.

Absence of nucleotide polymorphism in a Plasmodium vivax multidrug resistance gene after failure of mefloquine prophylaxis in French Guyana.

Vivax malaria is widespread and resistance has been described for chloroquine and sulfadoxine-pyrimethamine. We report on evidence of failure of mefloquine prophylaxis in a French soldier who contracted Plasmodium vivax in French Guyana, South America. Despite regular weekly mefloquine prophylaxis (250 mg/d), the patient presented with a first episode of vivax malaria, which was treated by chloroquine alone, then experienced a second crisis in France. The reappearance of the parasites occurred one day after the end of prophylaxis, confirming parasitological and clinical resistance in a non-immune patient. Mefloquine was detected by a liquid chromatography assay in plasma at a level of 1062 ng/ml, which was higher than the expected concentration after five months of weekly prophylaxis. This isolate had no single nucleotide polymorphisms of the pvmdr1 gene at seven allele positions: pvmdr1 N91, Y189, Y976, S1071, F1076, N1079 and D1291, corresponding to codons 86, 184, 939, 1034, 1039, 1042 and 1246 in P. falciparum. This observation of failure of mefloquine prophylaxis against P. vivax, when added to previously reported chloroquine and atovaquone-proguanil failure, strengthens the case for re-evaluating drug policies for vivax malaria and the need for continuous research on molecular markers of drug resistance.

[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.

[Stability of blood glucose collected with or without antiglycolytic agent]. / Stabilité de la glycémie avant centrifugation avec ou sans antiglycolytique.

Glycolysis in blood samples is well-known to induce a rapid decrease of glucose concentration and the use of an antiglycolysis is supposed to prevent this phenomenon. Fifteen healthy volunteers were included in this study. The aim was to evaluate the stability of glucose concentration in regard to the type of blood collection tube used (with or without antiglycolytic agent (monoiodoacetate)) and the time before centrifugation. During the first two hours, a similar decrease was observed with both kind of tube (about 9% in two hours), then the effect of the antiglycolytic agent became significant. It is re-emphasised that glycolysis inhibitor should be used for glucose determination, especially when centrifugation is delayed.

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.

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.

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.