References of "DE BACKER, Benjamin"
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See detailComparaison des performances de cinq tests rapides pour le diagnostic de l’angine à streptocoque du groupe A
DE BACKER, Benjamin ULg; GAVAGE, Pierre; MINON, Jean-Marc

Poster (2013, November)

Objet. Etude comparative des performances analytiques de tests immunochromatographiques pour la détection du streptocoque A dans les frottis de gorge : Quickvue (Quidel), bioNexia (bioMérieux), Clearview ... [more ▼]

Objet. Etude comparative des performances analytiques de tests immunochromatographiques pour la détection du streptocoque A dans les frottis de gorge : Quickvue (Quidel), bioNexia (bioMérieux), Clearview (Inverness medical), Dipromed et All-Diag. Méthodes. Les prélèvements utilisés ont été réalisés avec les E-Swab de chez Copan. Un total de 106 échantillons a été testé, dont 58 positifs et 48 négatifs. Environ la moitié des échantillons a été testée avec le format cassette et l’autre moitié avec le format dipstick pour les kits bioNexia et Clearview. Par ailleurs, les kits Dipromed et All-Diag (tous deux au format dipstick) ont été groupés dans cette étude car ils sont identiques (information confirmée par les fournisseurs). Les résultats des tests rapides ont été comparés à ceux de la culture prolongée. Les échantillons ont été ensemencés sur milieu CNA, avec disque de bacitracine pour l’identification présomptive du streptocoque A. Un groupage à l’aide de tests d’agglutination (Oxoid) et/ou une identification de la souche sur l’automate Vitek 2 (bioMérieux) ont été réalisés pour identification formelle. Sur base des résultats de l’étude, nous avons calculé la sensibilité et la spécificité de chaque kit. Ces valeurs ont ensuite été appliquées à la prévalence de cultures positives pour le streptocoque A observée au CHR Citadelle, en 2012. Nous avons ainsi pu calculer les valeurs prédictives positives (VPP) et négatives (VPN) sur notre population réelle. Résultats. La sensibilité est excellente pour tous les kits, comprise entre 93,1% (Clearview) et 96,6% (Quickvue). La spécificité est de 95,8% pour le Quickvue, tandis qu’elle est de 97,9% pour tous les autres kits. Sur la population du CHR Citadelle (2012), les VPP sont de 77,6% pour le Quickvue, et se situent aux alentours de 87% pour les autres kits. Les VPN sont excellentes et vont de 99 à 99,5%. Conclusion. Les valeurs de sensibilité et spécificité obtenues dans cette étude sont conformes à celles attendues pour ce genre de kit selon la littérature, c’est-à-dire respectivement supérieures à 90% et 95%. Les VPP observées avec le test Quickvue sont péjorées par l’existence d’un faux positif de plus. Les autres kits présentent une quasi-équivalence analytique dans notre série. [less ▲]

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See detailElévation faible d’hCG en dehors d’un contexte gravidique : à propos de deux cas et revue de la littérature
DE BACKER, Benjamin ULg; GOFFIN, Frédéric ULg; NISOLLE, Michelle ULg et al

in Annales de Biologie Clinique (2013), 71(4), 496-502

Unexpected finding or persistence of low human chorionic gonadotropin (hCG) levels is not a rare situation. It requires a clinico-biological approach in order to avoid misunderstandings that could lead to ... [more ▼]

Unexpected finding or persistence of low human chorionic gonadotropin (hCG) levels is not a rare situation. It requires a clinico-biological approach in order to avoid misunderstandings that could lead to inappropriate diagnostic or therapeutic attitudes. Beyond pregnancy, persistent low levels of hCG may be associated with various benign and malignant conditions, i.e. quiescent gestational trophoblastic disease (QTD), raised pituitary hCG or false positive elevation caused by circulating heterophile antibodies. We report the cases of two non-pregnant patients with low serum hCG. In the first case, hCG levels raised during several years following a spontaneous abortion. The likelihood of heterophilic antibodies interference was ruled out and extensive clinical investigation excluded the presence of a tumour. The diagnosis was QTD. In the second case, elevated hCG came to light as an incidental finding in a women with chronic renal failure and led the clinicians to question the laboratory. The cause was probably an increase in pituitary hCG consecutive to terminal renal failure. These cases illustrate the importance of understanding the biology of the hCG and the causes of its persistent low elevation, which are reviewed in this article. It is essential to demonstrate clinically the presence of a tumour in order to avoid unnecessary and ineffective chemotherapy and/or hysterectomy. [less ▲]

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See detailSimultaneous finding of hereditary spherocytosis in a mother and her daughter following parvovirus B19 infection
DE BACKER, Benjamin ULg; Ketelslegers, Olivier; Vasbien, Myriam et al

Poster (2012, October)

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See detailEvolution of the content of THC and other major cannabinoids in drug-type cannabis cuttings and seedlings during growth of plants
DE BACKER, Benjamin ULg; Maebe, Kevin; Verstraete, Alain G. et al

in Journal of Forensic Sciences (2012), 57(4), 918-922

In Europe, authorities frequently ask forensic laboratories to analyze seized cannabis plants to prove that cultivation was illegal (drug type and not fiber type). This is generally done with mature and ... [more ▼]

In Europe, authorities frequently ask forensic laboratories to analyze seized cannabis plants to prove that cultivation was illegal (drug type and not fiber type). This is generally done with mature and flowering plants. However, authorities are often confronted with very young specimens. The aim of our study was to evaluate when the chemotype of cannabis plantlets can be surely determined through analysis of eight major cannabinoids content during growth. Drug-type seedlings and cuttings were cultivated, sampled each week, and analyzed by high-performance liquid chromatography with diode array detection. The chemotype of clones was recognizable at any developmental stage because of high total Delta-9-tetrahydrocannabinol (THC) concentrations even at the start of the cultivation. Conversely, right after germination seedlings contained a low total THC content, but it increased quickly with plant age up, allowing chemotype determination after 3 weeks. In conclusion, it is not necessary to wait for plants’ flowering to identify drug-type cannabis generally cultivated in Europe. [less ▲]

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See detailDifferential Effects of Cocaine on Dopamine Neuron Firing in Awake and Anesthetized Rats
Koulchitsky, Stanislav ULg; DE BACKER, Benjamin ULg; Quertemont, Etienne ULg et al

in Neuropsychopharmacology : Official Publication of the American College of Neuropsychopharmacology (2012), 37

Cocaine (benzoylmethylecgonine), a natural alkaloid, is a powerful psychostimulant and a highly addictive drug. Unfortunately, the relationships between its behavioral and electrophysiological effects are ... [more ▼]

Cocaine (benzoylmethylecgonine), a natural alkaloid, is a powerful psychostimulant and a highly addictive drug. Unfortunately, the relationships between its behavioral and electrophysiological effects are not clear. We investigated the effects of cocaine on the firing of midbrain dopaminergic (DA) neurons, both in anesthetized and awake rats, using pre-implanted multielectrode arrays and a recently developed telemetric recording system. In anesthetized animals, cocaine (10 mg/kg, intraperitoneally) produced a general decrease of the firing rate and bursting of DA neurons, sometimes preceded by a transient increase in both parameters, as previously reported by others. In awake rats, however, injection of cocaine led to a very different pattern of changes in firing. A decrease in firing rate and bursting was observed in only 14% of DA neurons. Most of the other DA neurons underwent increases in firing rate and bursting: these changes were correlated with locomotor activity in 52% of the neurons, but were uncorrelated in 29% of them. Drug concentration measurements indicated that the observed differences between the two conditions did not have a pharmacokinetic origin. Taken together, our results demonstrate that cocaine injection differentially affects the electrical activity of DA neurons in awake and anesthetized states. The observed increases in neuronal activity may in part reflect the cocaine-induced synaptic potentiation found ex vivo in these neurons. Our observations also show that electrophysiological recordings in awake animals can uncover drug effects, which are masked by general anesthesia. [less ▲]

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See detailValidation of the quantitative determination of tetrahydrocannabinol and its two major metabolites in plasma by UHPLC/MS-MS according to the total error approach
DUBOIS, Nathalie ULg; Paccau, A.; DE BACKER, Benjamin ULg et al

in Journal of Analytical Toxicology (2012), 36(1), 25-29

In Belgium, driving under the influence (DUI) of cannabis is prohibited and has severe legal consequences for the driver if the blood plasma concentration of Δ9-tetrahydrocannabinol (THC) exceeds 1 µg/L ... [more ▼]

In Belgium, driving under the influence (DUI) of cannabis is prohibited and has severe legal consequences for the driver if the blood plasma concentration of Δ9-tetrahydrocannabinol (THC) exceeds 1 µg/L. A method to quantify low concentrations of THC and its hydroxylated (THC-OH) and carboxylated (THC-COOH) metabolites in plasma was developed for DUI but also for other applications. Ultra-high-performance liquid chromatography coupled to mass spectrometry seems to be a very convenient method to combine fast chromatographic separation and good sensitivity. The method was validated according to total error approach. Chromatographic separation was achieved in a 3-min total run time. The limits of quantitation were lower or equal to 1 µg/L for all compounds. The linearity of the method was acceptable in the validated range of concentrations (from 0.5 to 50 µg/L for THC, from 0.9 to 50 µg/L for THC-OH and from 1.1 to 100 µg/L for THC-COOH). The biases were lower than 13%, and the relative standard deviations for repeatability and intermediate precision did not exceed 15%. Lower and upper β-expectation tolerance limits did not exceed the acceptance limits of 20% for concentrations higher than 2 µg/L for THC and THC-OH and higher than 4 µg/L for THC-COOH. The acceptance limits were 30% for THC and THC-OH concentrations lower than 2 µg/L and for THC-COOH concentrations lower than 4 µg/L. [less ▲]

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See detailQuantification in postmortem blood and identification in urine of tramadol and its two main metabolites in two cases of lethal tramadol intoxication
De Backer, Benjamin ULg; Renardy, Françoise ULg; Denooz, Raphaël ULg et al

in Journal of Analytical Toxicology (2010), 34(9), 599-604

Tramadol has been extensively prescribed for two decades. It is an opioid analgesic considered to induce fewer side effects than other compounds of this class. However, serious complications may occur in ... [more ▼]

Tramadol has been extensively prescribed for two decades. It is an opioid analgesic considered to induce fewer side effects than other compounds of this class. However, serious complications may occur in case of intoxication. We report here two cases of fatal intoxication due to tramadol ingestion. Tramadol, O-desmethyltramadol (ODT) and N-desmethyltramadol (NDT) were quantitatively and qualitatively determined in postmortem blood and urine, respectively. An HPLC method coupled with fluorescence detection was validated using total error approach for the analysis of tramadol, ODT, and NDT in blood. In case1, concentrations of tramadol and its metabolites were 7.7 mg/L (tramadol), 1.33 mg/L (ODT), and 0.6mg/L (NDT). In case 2, concentrations found were 48.34 mg/L (tramadol), 2.43 mg/L (ODT), and 10.09 mg/L (NDT). Opposite ratios of ODT/NDT concentrations observed in different cases were suggested to be useful for the evaluation of the delay between ingestion and death. However, the changes in metabolites levels may also be explained by pharmacokinetic interactions and quantitative differences in the activity of the cytochrome-P450 2D6. Interestingly, norfluoxetine was detected in sub-therapeutic levels in case 2. Most of these aspects in tramadol-related fatalities are reviewed in this paper, and an overview of fatal intoxications due to tramadol is presented. [less ▲]

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See detailQuantitative determination of cannabinoids in serum by UHPLC/MS-MS
Dubois, Nathalie ULg; Paccou, A.; DE BACKER, Benjamin ULg et al

Poster (2010, April)

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See detailLe Cannabis: historique, culture et modes d'utilisation
Theunis, Laetitia ULg; De Backer, Benjamin ULg; Charlier, Corinne ULg

in Regards croisés sur le Cannabis (2010)

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See detailQuantification in postmortem blood and identification in urine of tramadol and its two main metabolites in two cases of lethal tramadol intoxication
De Backer, Benjamin ULg; Renardy, Françoise ULg; Denooz, Raphael ULg et al

in Mitteilungsblatt der Gesellschaft für Toxikologische und Forensische Chemie (2010), 77(3), 252

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See detailInnovative development and validation of an HPLC/DAD method for the qualitative and quantitative determination of major cannabinoids in cannabis plant material
De Backer, Benjamin ULg; Debrus, Benjamin ULg; Lebrun, Pierre ULg et al

in Journal of Chromatography. B : Analytical Technologies in the Biomedical & Life Sciences (2009), 877(32), 4115-4124

GC is commonly used for the analysis of cannabis samples, e.g. in forensic chemistry. However, as this method is based on heating of the sample, acidic forms of cannabinoids are decarboxylated into their ... [more ▼]

GC is commonly used for the analysis of cannabis samples, e.g. in forensic chemistry. However, as this method is based on heating of the sample, acidic forms of cannabinoids are decarboxylated into their neutral counterparts. Conversely, HPLC permits the determination of the original composition of plant cannabinoids by direct analysis. Several HPLC methods have been described in the literature, but most of them failed to separate efficiently all the cannabinoids or were not validated according to general guidelines. By use of an innovative methodology for modelling chromatographic responses, a simple and accurate HPLC/DAD method was developed for the quantification of major neutral and acidic cannabinoids present in cannabis plant material: Δ9-tetrahydrocannabinol (THC), THC-acid (THCA), cannabidiol (CBD), CBD-acid (CBDA), cannabigerol (CBG), CBG-acid (CBGA) and cannabinol (CBN). Δ8-tetrahydrocannabinol (∆8-THC) was determined qualitatively. Following the practice of design of experiments, predictive multilinear models were developed and used in order to find optimal chromatographic analytical conditions. The method was validated following an approach using accuracy profiles based on β-expectation tolerance intervals for the total error measurement, and assessing the measurements uncertainty. This analytical method can be used for diverse applications, e.g. plant phenotype determination, evaluation of psychoactive potency and control of material quality. [less ▲]

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See detailInnovative development and validation of an HPLC/DAD method for the qualitative and quantitative determination of major cannabinoïds in cannabis plant material
De Backer, Benjamin ULg; Debrus, Benjamin ULg; Lebrun, Pierre ULg et al

Poster (2009, August)

GC is commonly used for the analysis of cannabis samples, e.g. in forensic chemistry. However, as this method is based on heating of the sample, acidic forms of cannabinoids are decarboxylated into their ... [more ▼]

GC is commonly used for the analysis of cannabis samples, e.g. in forensic chemistry. However, as this method is based on heating of the sample, acidic forms of cannabinoids are decarboxylated into their neutral counterparts. Converely, HPLC permits the determination of the original composition of plant cannabinoids by direct analysis. Several HPLC methods have been described in the literature, but most of them failed to separate efficiently all the cannabinoids or were not validated according to general guidelines. By use of an innovative methodology for modelling chromatographic responses, a simple and accurate HPLC/DAD method was develop [less ▲]

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See detailCocaïne: Détermination du délai entre le prélèvement et la consommation
De Backer, Benjamin ULg

Conference (2008, November 14)

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