Pierre Wallemacq - Academia.edu (original) (raw)

Papers by Pierre Wallemacq

Research paper thumbnail of Evaluation of peritoneal transport properties at onset of peritoneal dialysis and longitudinal follow-up

Background. The clinical determinants of baseline peritoneal membrane (PM) transport characterist... more Background. The clinical determinants of baseline peritoneal membrane (PM) transport characteristics, as evaluated by a hypertonic peritoneal equilibration test (PET), remain ill-defined. Likewise, the longi- tudinal evolution of PM transport properties in peritoneal dialysis (PD) patients given automated PD (APD) and icodextrin still needs to be determined precisely. The aims of the present study were (1) to determine the clinical

Research paper thumbnail of Pharmacokinetic Basis for the Efficient and Safe Use of Low-Dose Mycophenolate Mofetil in Combination with Tacrolimus in Kidney Transplantation

has been shown in patients receiving Tc-MMF combination therapy compared with CsA-MMF combination... more has been shown in patients receiving Tc-MMF combination therapy compared with CsA-MMF combination therapy at the same dose of MMF. The aim of this prospective study was to assess the pharmacokinetic/ pharmacodynamic (PK/PD) relationship for MPA in kidney transplant patients receiving low-dose MMF (500 mg twice a day) in combination with Tc. Methods: Adult kidney transplant recipients (n ‫؍‬ 51) were included. MPA-PK profiles (blood sampling at 0, 0.5, 1, 2, 4, 6, and 12 h after MMF oral dose) were obtained within the first 2 weeks after transplantation, 3 months after grafting, and at every adverse clinical event [side effect or acute rejection (AR)]. All patients received Tc, MMF (500 mg twice a day), and steroids. Results: Thirty patients (59%) had uneventful outcomes, and 21 patients had 33 episodes of MPA-related side effects; only 3 patients had AR. A total of 78 MPA-PK profiles were obtained. The following PK parameters were increased in the side-effects group compared with the non-side effects group: mean MPA c min , 2.63 ؎ 1.58 vs 1.75 ؎ 0.82 mg/L (P ‫؍‬ 0.016); mean c 30 , 10.47 ؎ 6.27 vs 7.66 ؎ 8.95 mg/L (P ‫؍‬ 0.009); mean c 60 , 9.67 ؎ 5.42 vs 5.83 ؎ 2.6 mg/L (P ‫؍‬ 0.0002); mean area under the MPA time-concentration curve from 0 to 12 h [MPA-AUC (0 -12) ], 48.38 ؎ 18.5 vs 36.04 ؎ 10.82 mg ⅐ h/L (P ‫؍‬ 0.0006); mean dose-normalized MPA-AUC, 0.16 ؎ 0.05 vs 0.12 ؎ 0.04 (mg ⅐ h/L)/(mg/m 2 ) (P ‫؍‬ 0.0015). For the three AR patients, MPA concentrations obtained at the time of AR revealed MPA c min values of 1.86, 1.76, and 3.83 mg/L, respectively, and MPA-AUC (0 -12) values of 37.7, 24.9, and 104.9 mg ⅐ h/L. The threshold of toxicity was 3 mg/L (sensitivity, 38.7%; specificity, 91.5%) for c min , 8.09 mg/L for maximum MPA concentration during the first hour (sensitivity, 77.8%; specificity, 67.4%), and 37.6 mg ⅐ h/L for MPA-AUC (0 -12) (sensitivity, 83.3%; specificity, 59.6%). Conclusions: These results demonstrate the relationship between plasma MPA concentrations and toxicity. High c min, c 30 , and c 60 values as well as AUC (0 -12) are associated with increased risk for side effects. These values may have an importance in a routine monitoring program.

Research paper thumbnail of Validation of a HPLC-MS/MS assay for the determination of total and unbound concentration of temocillin in human serum

Clinical biochemistry, Jan 21, 2015

The aim of this study was to develop and validate a HPLC-MS/MS assay to determine total and unbou... more The aim of this study was to develop and validate a HPLC-MS/MS assay to determine total and unbound concentrations of temocillin in serum samples. Methanolic protein precipitation and ultrafiltration were used for total and unbound concentration extraction, respectively. Extract was injected into a LC-MS/MS system. Reversed phase chromatography was performed on a phenyl grafted column in gradient mode. Temocillin and internal standard (ticarcillin) were identified in positive electrospray ionization mode using ion transitions of m/z 415.34>339.1 and 385.31>160.3, respectively. Temocillin total and unbound concentration quantification assays were linear over concentrations ranging from 1 to 500mg/L and from 0.5 to 300mg/L, respectively. Both assays presented acceptable intra and inter-assay precision and accuracy <13.9%. Limits of quantification and detection were of 1 and 0.10mg/L, and 0.5 and 0.05mg/L for total and unbound concentration respectively. Total temocillin conce...

Research paper thumbnail of par le Virus de l'immunodéfi cience humaine (VIH) et son traitement au Mali

Research paper thumbnail of Does the Russell Viper Venom time test provide a rapid estimation of the intensity of oral anticoagulation? A cohort study

Thrombosis Research, 2015

Background: Dilute Russell Viper Venom Time (DRVV-T) might be useful in urgent settings for scree... more Background: Dilute Russell Viper Venom Time (DRVV-T) might be useful in urgent settings for screening patients on Non-VKA Oral Anticoagulants (NOACs). Aim: To compare the accuracy of DRVV-T with gold standard assays for the assessment of pharmacodynamics of dabigatran, rivaroxaban and vitamin K antagonist (VKA) in plasma samples from patients. Methods: Sixty rivaroxaban, 48 dabigatran and 50 VKA samples from patients were included. DRVV-T was performed in all groups using STA ® -Staclot ® DRVV-Screen and -Confirm. For NOACs, PT and aPTT were performed using different reagents while plasma drug concentrations were measured by liquid mass-spectrometry (LC-MS/MS). For VKA, INR was performed using RecombiPlasTin 2G ® . Results: For NOACs, correlations between calibrated STA ® -Staclot ® DRVV-Confirm and LC-MS/MS (rs = 0.88 and 0.97 for rivaroxaban and dabigatran, respectively) were higher than the ones obtained with STA ® -Staclot ® DRVV-Screen (rs = 0.87 and 0.91), PT (rs = 0.83 to 0.86) or aPTT (rs = 0.84 to 0.89). Bland Altman analyses showed that calibrated DRVV-T methods tend to overestimate plasma concentrations of NOACs. ROC curves revealed that cut-off to exclude supra-therapeutic levels at C trough (i.e. 200 ng/mL) are different for dabigatran and rivaroxaban. Neither STA ® -Staclot ® DRVV-Screen nor -Confirm correlated sufficiently with the intensity of VKA therapy (rs = 0.35 and 0.52). Conclusions: STA ® -Staclot ® DRVV-Confirm provides a rapid estimation of the intensity of anticoagulation with rivaroxaban or dabigatran without specific calibrators. At C trough , thresholds for rivaroxaban and dabigatran can be used to identify supra-therapeutic plasma level. However, this test cannot differentiate the nature of the NOACs. The development of a point-of-care device optimising this method would be of particular interest in emergency situations.

Research paper thumbnail of Could trisialotransferrin be used as an additional biomarker to CDT in order to improve detection of chronic excessive alcohol intake?

Clinical Biochemistry, 2014

Carbohydrate-deficient transferrin is a well-known biomarker widely used for detection of chronic... more Carbohydrate-deficient transferrin is a well-known biomarker widely used for detection of chronic excessive alcohol intake. However, under certain clinical conditions particularly frequently met amongst heavy drinkers (steatosis, fibrosis, cirrhosis…), it isn&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;t a reliable biomarker. In this study, we tried to find additional biomarkers to CDT in order to improve detection of chronic excessive alcohol intake. We conducted a retrospective cohort study from December 2007 to December 2009. We focused mainly on three different groups: heavy drinking patients with active alcohol consumption (n=243), cirrhotic patients (abstinent patients and non alcoholic cirrhosis, n=44) and control group (n=85). In our study, CDT showed a poor sensitivity for diagnosis of heavy drinking patients (around 63%, and even lower) for cirrhotic patients and patients at advanced stage of fibrosis. Combination of CDT with trisialotransferrin enabled to improve significantly sensitivity and specificity (p-value AUC ROC&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). When adding mean corpuscular volume and gamma-glutamyltransferase to this first combination, performances were even better (p-value&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). This second cluster enabled to make a statistically significant difference between cirrhotic patients with active alcohol consumption compared to abstinent cirrhotic patients and to non alcoholic cirrhotic patients (p-value&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). From our study, trisialotransferrin seems to be a useful additional biomarker to CDT in order to improve detection of chronic excessive alcohol intake.

Research paper thumbnail of Ultra-high performance liquid chromatography tandem mass spectrometric method for the determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots--development, validation and clinical application during breast cancer adjuvant therapy

Talanta, 2015

A LC-MSMS method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxy... more A LC-MSMS method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots samples was developed and validated. The method employs an ultrasound-assisted liquid extraction and a reversed phase separation in an Acquity(®) C18 column (150×2.1 mm, 1.7 µm). Mobile phase was a mixture of formic acid 0.1% (v/v) pH 2.7 and acetonitrile (gradient from 60:40 to 50:50, v/v). Total analytical run time was 8 min. Precision assays showed CV % lower than 10.75% and accuracy in the range 94.5 to 110.3%. Mean analytes recoveries from DBS ranged from 40% to 92%. The method was successfully applied to 91 paired clinical DBS and plasma samples. Dried blood spots concentrations were highly correlated to plasma, with rs>0.83 (P<0.01). Median estimated plasma concentrations after hematocrit and partition factor adjustment were: TAM 123.3 ng mL(-1); NDT 267.9 ng mL(-1), EDF 10.0 ng mL(-1) and HTF 1.3 ng mL(-1,) representing in averag...

Research paper thumbnail of Correlation of mycophenolic acid pharmacokinetic parameters with side effects in kidney transplant patients treated with mycophenolate mofetil

Clinical chemistry, 2001

Mycophenolate mofetil (MMF) is widely used in organ transplantation to prevent acute rejection. B... more Mycophenolate mofetil (MMF) is widely used in organ transplantation to prevent acute rejection. Because MMF can produce hematologic and/or gastrointestinal toxicity, therapeutic monitoring is becoming mandatory. This study was designed to investigate the relationship between the clinical events and the pharmacokinetics of mycophenolic acid (MPA) in adult renal transplantation. Thirty-one adult kidney recipients were prospectively included in the study. MPA pharmacokinetic profiles (blood sampling at 0, 0.5, 1, 2, 4, 6, and 12 h after MMF oral dose) were obtained after transplantation (desired creatinine clearance, 40 mL/min), at 3 months after grafting, and at every clinical event (e.g., side effect or rejection). All patients received a 10-day course of anti-thymocyte globulin, cyclosporine, MMF (1 g twice daily), and steroids. We divided the 31 patients into two groups (groups 1 and 2). Ten patients (32%; group 1) had uneventful outcomes, and 21 patients (68%; group 2) presented w...

Research paper thumbnail of Is plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) determination in donors and recipients predictive of renal function after kidney transplantation?

Clinical biochemistry, 2014

Delayed graft function (DGF) is still a major issue in kidney transplantation. Plasma and urine n... more Delayed graft function (DGF) is still a major issue in kidney transplantation. Plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) were evaluated in a population of kidney donors and recipients to investigate their performance to predict early renal function. Plasma (pNGAL) and urine (uNGAL) samples were obtained from donors before organ procurement, and from recipients before transplantation, and then 6, 24 and 48h after the procedure. Kidney transplantations were performed from both living donors (LDs, n=17) and deceased donors (DDs, n=80). Recovery of renal function was evaluated as the time to reach serum creatinine <2mg/l or glomerular filtration rate (GFR)>40mL/min. Logistic regression was used to assess the ability of different variables to predict the occurrence of DGF. Plasma NGAL levels were significantly lower in LDs than in DDs. No episodes of DGF were recorded among LD kidney recipients, but DGF was observed in 25% of patients in the DD group. There...

Research paper thumbnail of Modelled target attainment after meropenem infusion in patients with severe nosocomial pneumonia: the PROMESSE study

The Journal of antimicrobial chemotherapy, 2015

The objective of this study was to propose an optimal treatment regimen of meropenem in criticall... more The objective of this study was to propose an optimal treatment regimen of meropenem in critically ill patients with severe nosocomial pneumonia. Among 55 patients in intensive care treated with 1 g of meropenem every 8 h for severe nosocomial pneumonia, 30 were assigned to intermittent infusion (II; over 0.5 h) and 25 to extended infusion (EI; over 3 h) groups. Based on plasma and epithelial lining fluid (ELF) concentrations determined at steady-state, pharmacokinetic modelling and Monte Carlo simulations were undertaken to assess the probability of attaining drug concentrations above the MIC for 40%-100% of the time between doses (%T > 1-fold and 4-fold MIC), for 1 or 2 g administered by either method. Penetration ratio, measured by the ELF/plasma ratio of AUCs, was statistically higher in the EI group than in the II group (mean ± SEM: 0.29 ± 0.030 versus 0.20 ± 0.033, P = 0.047). Considering a maximum susceptibility breakpoint of 2 mg/L, all dosages and modes of infusions achi...

Research paper thumbnail of Sirolimus and Tacrolimus Trough Concentrations and Dose Requirements after Kidney Transplantation in Relation to CYP3A5 and MDR1 Polymorphisms and Steroids

Transplantation, 2005

CYP3A5 and MDR1 polymorphisms have been shown to influence tacrolimus blood concentrations and do... more CYP3A5 and MDR1 polymorphisms have been shown to influence tacrolimus blood concentrations and dose requirements. The aim is to determine whether these polymorphisms also affect sirolimus trough concentrations and dose requirements after kidney transplantation. Eighty-five renal transplant recipients receiving sirolimus were included. Twenty-four were treated with a combined sirolimus-tacrolimus regimen. Eighty-one patients received steroids. Sirolimus and tacrolimus were adjusted to a target therapeutic window. CYP3A5 (intron 3) and MDR1 (exons 12, 21, 26) genotypes were correlated to the adjusted trough concentrations and dose requirements for both sirolimus and tacrolimus. There were no significant correlation between adjusted sirolimus trough concentrations or dose requirements and genetic polymorphisms. In a multiple regression model, adjusted-prednisone dose was involved with a positive or negative effect when considering sirolimus dose requirements or adjusted concentrations, respectively. In the subgroup of patients treated by tacrolimus and sirolimus, adjusted tacrolimus doses were higher in patients carrying at least one CYP3A5 *1 allele (median 0.083 vs. 0.035 mg/kg for CYP3A5*3/*3 patients, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). Adjusted-prednisolone dose and CYP3A5 polymorphism explained up to 61% of the variability in tacrolimus dose requirements. Unlike tacrolimus, sirolimus adjusted trough concentrations and dose requirements seem not affected by CYP3A5 and MDR1 polymorphisms. Adjusted-prednisone dose has a significant impact on tacrolimus and sirolimus dose requirements.

Research paper thumbnail of Biotransformation Enzymes and Drug Transporters Pharmacogenetics in Relation to Immunosuppressive Drugs: Impact on Pharmacokinetics and Clinical Outcome

Transplantation, 2008

Immunosuppressive drugs commonly used after organ transplantation to prevent acute rejection incl... more Immunosuppressive drugs commonly used after organ transplantation to prevent acute rejection including tacrolimus, cyclosporine, sirolimus, and mycophenolic acid are characterized by a narrow therapeutic index and broad interindividual variability in their pharmacokinetics. Adequate immunosuppression aims to reach an optimal benefit-risk ratio. Therapeutic drug monitoring represents a crucial step in routine practice to maintain blood concentrations within the target window, because the bioavailability of these drugs depends on their absorption, distribution, biotransformation, and elimination. Single nucleotide polymorphisms (SNPs) in genes encoding biotransformation enzymes (CYP3A) and drug transporters (ABCB1) have opened up a promising way for the selection of individual dosages. The relationship of these SNPs with immunosuppressive drug pharmacokinetics was extensively studied after kidney, liver, heart, and lung transplantations. Patient susceptibility to nephrotoxicity in the long term was also reported in relation to some SNPs, which could allow effective assessment of individual risk and selection of treatment according to patient parameters. Further studies are needed to provide evidence that a genetic analysis combined with therapeutic drug monitoring has the potential to optimize drug use after transplantation.

Research paper thumbnail of CONVERSION FROM CYCLOSPORINE TO FK506 FOR SALVAGE OF IMMUNOCOMPROMISED PEDIATRIC LIVER ALLOGRAFTS EFFICACY, TOXICITY, AND DOSE REGIMEN IN 23 CHILDREN

Transplantation, 1994

Twenty-three pediatric liver transplant recipients (median age 3.9 years) were converted from cyc... more Twenty-three pediatric liver transplant recipients (median age 3.9 years) were converted from cyclosporine A-based immunosuppression to FK506 for uncontrollable acute rejection (AR; n = 16), chronic rejection (n = 4), or predominantly nonspecific hepatitis (n = 3). Of these, 19 had received poly- or monoclonal anti-T lymphocyte antibodies either for AR prophylaxis or therapy before FK506 conversion. Full clinical and histologic responses to FK506 therapy were observed in 11/16 cases of AR compared with 0/7 cases of non-AR indications (P = 0.006). Acute FK506 toxicity included renal dysfunction in 12/23 children (52%), neurological disorders in 7/23 (30%), and isolated hyperkalemia in 2/23 (9%), with a poor correlation with the corresponding FK506 trough plasma level. Moreover, a significant impairment of glomerular filtration rate was recorded in the 12 children who received FK506 treatment for more than 6 months (P = 0.002). FK506 therapy had to be definitively withdrawn in 6 cases (fatal infections: n = 4; persistent tremor: n = 1; reason unrelated to FK506: n = 1). Five children developed a lymphoproliferative syndrome (LPS), leading to death in 3 cases despite cessation of the immunosuppressive therapy; in the other 2 patients, LPS was controlled, and the children were successfully retransplanted for chronic rejection under FK506. The occurrence of Epstein-Barr virus primary infection under FK506 therapy was found to constitute a significant risk factor for LPS (P = 0.027). In summary, full response to FK506 conversion was observed in 69% of uncontrollable AR cases; however, 74% and 22% of this probably over-immunosuppressed population experienced major adverse events and LPS under FK506 therapy, respectively.

Research paper thumbnail of EARLY HEPATOCYTE, ENDOTHELIAL, AND BILE DUCT CELL INJURY AFTER PEDIATRIC LIVER TRANSPLANTATION FROM CADAVERIC OR LIVING-RELATED DONORS

Transplantation, 1998

Background. When compared with cadaveric grafts (Cad), the potential advantages of pediatric orth... more Background. When compared with cadaveric grafts (Cad), the potential advantages of pediatric orthotopic liver transplantation (OLT) from living-related (LR) donors may include better graft quality, shorter ischemic time, appropriate preparation of the recipient, and better immunologic compatibility.

Research paper thumbnail of Clinical pharmacokinetics of Neoral in pediatric recipients of primary liver transplants

Transplant International, 1997

Pediatric liver transplant recipients constitute a population characterized by a particularly unp... more Pediatric liver transplant recipients constitute a population characterized by a particularly unpredictable and poor bioavailability of cyclosporin (CyA). Even though several adult studies show that the new oral formulation of CyA, Neoral (NEO), produces better bioavailability and blood level predictability, few data describe its pharmacokinetics in children. We performed a complete analysis of the pharmacokinetics of NEO in ten small children after primary liver transplantation. Three pharmacokinetic profiles were set up with data obtained from tests taken during i. v. administration of CyA, after the first oral NEO dose, and after the last NEO dose before discharge from the hospital. The mean halflives obtained were 8.1, 7.7, and 6.9 h, respectively, and the bioavailabilities were 22 YO and 21 % for the first and last NEO doses. A large in-

Research paper thumbnail of Endoxifen Levels and Its Association With CYP2D6 Genotype and Phenotype

Therapeutic Drug Monitoring, 2012

Background: An association between CYP2D6 variation and clinical outcomes among women with breast... more Background: An association between CYP2D6 variation and clinical outcomes among women with breast cancer treated with tamoxifen (TAM) has been demonstrated, such that the presence of 2 functional CYP2D6 alleles was associated with better clinical outcomes. This association is mainly due to the CYP2D6-mediated hydroxylation of N-desmethyltamoxifen (NDT) to yield endoxifen (EDF), which because of its high antiestrogenic potency, is mainly responsible for the therapeutic efficacy of TAM. The aim of this study was to evaluate the relation of CYP2D6 genotyping and phenotyping with EDF levels and [NDT]/[EDF] metabolic ratio in breast cancer patients from South of Brazil under TAM therapy.

Research paper thumbnail of Opportunities to Optimize Tacrolimus Therapy in Solid Organ Transplantation: Report of the European Consensus Conference

Therapeutic Drug Monitoring, 2009

In 2007, a consortium of European experts on tacrolimus (TAC) met to discuss the most recent adva... more In 2007, a consortium of European experts on tacrolimus (TAC) met to discuss the most recent advances in the drug/dose optimization of TAC taking into account specific clinical situations and the analytical methods currently available and drew some recommendations and guidelines to help clinicians with the practical use of the drug. Pharmacokinetic, pharmacodynamic, and more recently pharmacogenetic approaches aid physicians to individualize long-term therapies as TAC demonstrates a high degree of both between- and within-individual variability, which may result in an increased risk of therapeutic failure if all patients are administered a uniform dose. TAC has undoubtedly benefited from therapeutic drug monitoring, but interpretation of the blood concentration is confounded by the relative differences between the assays. Single time points, limited sampling strategies, and area under concentration-time curve have all been considered to determine the most appropriate sampling procedure that correlates with efficacy. Therapeutic trough TAC concentration ranges have changed since the initial introduction of the drug, while still maintaining adequate immunosuppression and avoiding drug-related adverse effects. Pharmacodynamic markers have also been considered advantageous to the clinician, which may better reflect efficacy and safety, taking into account the between-individual variability rather than whole blood concentrations. The choice of method, differences between methods, and potential pitfalls of the method should all be considered when determining TAC concentrations. The recommendations of this consensus meeting regarding the analytical methods include the following: encourage the development and promote the use of analytical methods displaying a lower limit of quantification (1 ng/mL), perform careful validation when implementing a new analytical assay, participate in external proficiency testing programs, promote the use of certified material as calibrators in high-performance liquid chromatography with mass spectrometric detection methods, and take account of the assay and intermethod bias when comparing clinical trial outcomes. It is also important to consider that TAC concentrations may also be influenced by other factors such as specific pharmacokinetic characteristics associated with the population, drug interactions, pharmacogenetics, adverse events that may alter TAC concentrations, and any change in the oral formulation that may result in pharmacokinetic changes. This meeting emphasized the importance of obtaining multicenter prospective trials to assess the efficacy of alternative strategies to TAC trough concentrations whether it is other single time points or area under the concentration-time curve Bayesian estimation using limited sampling strategies and to select, standardize, and validate routine biomarkers of TAC pharmacodynamics.

Research paper thumbnail of Multi-site Analytical Evaluation of the Abbott ARCHITECT Tacrolimus Assay

Therapeutic Drug Monitoring, 2009

The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Ta... more The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Tacrolimus immunoassay. Proficiency panels and specimens from a population of organ transplant recipients were analyzed in 6 clinical laboratories in Europe and the United States, and the results were compared with other methods. The ARCHITECT assay requires a whole blood specimen pretreatment step with methanol/zinc sulfate to precipitate protein and extract the drug, followed by a 30-minute immunoassay using anti-tacrolimus antibody-coated paramagnetic microparticles and an acridinium-tacrolimus tracer. The assay was free from hematocrit interference in the range 25%-55% and from interference by extremes of cholesterol, triglycerides, bilirubin, total protein, and uric acid. The total percent of coefficient of variations of the assay were 4.9%-7.6% at 3 ng/mL, 2.9%-4.6% at 8.6 ng/mL, and 3.1%-8.2% at 15.5 ng/mL. Limit of detection was &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or =0.5 ng/mL and limit of quantification (LOQ) ranged from 0.69 to 1.07 ng/mL across the 6 sites (based on the upper 95% confidence interval concentrations). The 2007 European Consensus Conference on Tacrolimus Optimization recommended the use of assay methods with an LOQ around 1 ng/mL, based upon the need to measure trough tacrolimus blood concentrations precisely down to 3 ng/mL during low-dose tacrolimus regimens. Tacrolimus International Proficiency Testing Scheme samples were measured by the ARCHITECT immunoassay at 5 sites and showed an average bias of -0.28 to +0.85 ng/mL versus IMx Tacrolimus II immunoassay historical values and -0.21 to +0.68 ng/mL versus liquid chromatography/tandem mass spectrometry (LC-MSMS) Tacrolimus historical values. Method comparison studies were performed with the ARCHITECT Tacrolimus immunoassay on patient specimens with the following results: ARCHITECT Tacrolimus assay versus the Abbott IMx Tacrolimus II immunoassay (4 sites) yielded average biases between -0.94 and +0.26 ng/mL; ARCHITECT assay versus the Dade Dimension Tacrolimus immunoassay (2 sites) yielded average biases of -0.46 and +0.11 ng/mL; and ARCHITECT assay versus LC-MSMS methods at 2 sites yielded average biases of +0.51 and +1.63 ng/mL. Spearman correlation coefficients were &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;/=0.90 on all method comparisons. The ARCHITECT Tacrolimus assay is a semiautomated, robust, and highly sensitive immunoassay, representing an alternative approach for laboratories not equipped with LC-MSMS, and meets the 1 ng/mL recommendation of LOQ by the European Consensus Conference on Tacrolimus Optimization.

Research paper thumbnail of Increased Tissue Arachidonic Acid and Reduced Linoleic Acid in a Mouse Model of Cystic Fibrosis Are Reversed by Supplemental Glycerophospholipids Enriched in Docosahexaenoic Acid

Journal of Nutrition, 2009

An imbalance in (n-6)/(n-3) PUFA has been reported in cystic fibrosis (CF) patients. Glycerophosp... more An imbalance in (n-6)/(n-3) PUFA has been reported in cystic fibrosis (CF) patients. Glycerophospholipids enriched in docosahexaenoic acid (GPL-DHA) have been shown to regulate the (n-6)/(n-3) fatty acid ratio in the elderly. Here, we tested the effect of GPL-DHA supplementation on PUFA status in F508del homozygous CF mice. GPL-DHA liposomes were administrated by gavage (60 mg DHA/kg daily, i.e. at maximum 1.4 mg DHA/d) to 1.5-mo-old CF mice (CF+DHA) and their corresponding wild-type (WT) homozygous littermates (WT+DHA) for 6 wk. The PUFA status of different tissues was determined by GC and compared with control groups (CF and WT). There was an alteration in the (n-6) PUFA pathway in several CF-target organs in CF compared with WT mice, as evidenced by a higher level of arachidonic acid (AA) in membrane phospholipids or whole tissue (21 and 39% in duodenum-jejunum, 32 and 38% in ileum, and 19 and 43% in pancreas). Elevated AA levels were associated with lower linoleic acid (LA) and higher dihomo-g-linolenic acid levels. No DHA deficiency was observed. GPL-DHA treatment resulted in different PUFA composition changes depending on the tissue (increase in LA, decrease in elevated AA, DHA increase, increase in (n-6)/(n-3) fatty acid ratio). However, the DHA/ AA ratio consistently increased in all tissues in CF+DHA and WT+DHA mice. Our study demonstrates the effectiveness of an original oral DHA formulation in counter-balancing the abnormal (n-6) fatty acid metabolism in organs of CF mice when administrated at a low dose and highlights the potential of the use of GPL-DHA as nutritherapy for CF patients. J. Nutr.

Research paper thumbnail of CYP3A5 and ABCB1 polymorphisms influence tacrolimus concentrations in peripheral blood mononuclear cells after renal transplantation

Pharmacogenomics, 2010

This prospective study investigated the effect of genetic polymorphisms in a biotransformation en... more This prospective study investigated the effect of genetic polymorphisms in a biotransformation enzyme (CYP3A5) and a transporter protein (ABCB1) on tacrolimus (Tac) whole blood concentrations in renal transplantation, and more specifically on peripheral blood mononuclear cell (PBMC) drug concentrations, after renal transplantation. A total of 96 renal transplant recipients were genotyped for the exon 11 (1199G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;A), 21 (3435C&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T) and 26 (2677G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T/A) polymorphisms in the ABCB1 gene and for the intron 3 polymorphism in the CYP3A5 gene. Tac blood and PBMC concentrations were determined at day 7 after transplantation and at steady state, and then compared with recipient genotypes. The ABCB1 1199G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;A, 3435C&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T and 2677G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T/A SNPs, appeared to reduce the activity of P-glycoprotein towards Tac, increasing Tac PBMC concentrations. The impact of ABCB1 genetic polymorphisms on Tac blood concentrations was negligible. As increased Tac intracellular concentrations might in turn enhance immunosuppressive status and prevention or rejection, ABCB1 recipient genotyping might be useful to better individualize the Tac immunosuppressive therapy in renal transplantation.

Research paper thumbnail of Evaluation of peritoneal transport properties at onset of peritoneal dialysis and longitudinal follow-up

Background. The clinical determinants of baseline peritoneal membrane (PM) transport characterist... more Background. The clinical determinants of baseline peritoneal membrane (PM) transport characteristics, as evaluated by a hypertonic peritoneal equilibration test (PET), remain ill-defined. Likewise, the longi- tudinal evolution of PM transport properties in peritoneal dialysis (PD) patients given automated PD (APD) and icodextrin still needs to be determined precisely. The aims of the present study were (1) to determine the clinical

Research paper thumbnail of Pharmacokinetic Basis for the Efficient and Safe Use of Low-Dose Mycophenolate Mofetil in Combination with Tacrolimus in Kidney Transplantation

has been shown in patients receiving Tc-MMF combination therapy compared with CsA-MMF combination... more has been shown in patients receiving Tc-MMF combination therapy compared with CsA-MMF combination therapy at the same dose of MMF. The aim of this prospective study was to assess the pharmacokinetic/ pharmacodynamic (PK/PD) relationship for MPA in kidney transplant patients receiving low-dose MMF (500 mg twice a day) in combination with Tc. Methods: Adult kidney transplant recipients (n ‫؍‬ 51) were included. MPA-PK profiles (blood sampling at 0, 0.5, 1, 2, 4, 6, and 12 h after MMF oral dose) were obtained within the first 2 weeks after transplantation, 3 months after grafting, and at every adverse clinical event [side effect or acute rejection (AR)]. All patients received Tc, MMF (500 mg twice a day), and steroids. Results: Thirty patients (59%) had uneventful outcomes, and 21 patients had 33 episodes of MPA-related side effects; only 3 patients had AR. A total of 78 MPA-PK profiles were obtained. The following PK parameters were increased in the side-effects group compared with the non-side effects group: mean MPA c min , 2.63 ؎ 1.58 vs 1.75 ؎ 0.82 mg/L (P ‫؍‬ 0.016); mean c 30 , 10.47 ؎ 6.27 vs 7.66 ؎ 8.95 mg/L (P ‫؍‬ 0.009); mean c 60 , 9.67 ؎ 5.42 vs 5.83 ؎ 2.6 mg/L (P ‫؍‬ 0.0002); mean area under the MPA time-concentration curve from 0 to 12 h [MPA-AUC (0 -12) ], 48.38 ؎ 18.5 vs 36.04 ؎ 10.82 mg ⅐ h/L (P ‫؍‬ 0.0006); mean dose-normalized MPA-AUC, 0.16 ؎ 0.05 vs 0.12 ؎ 0.04 (mg ⅐ h/L)/(mg/m 2 ) (P ‫؍‬ 0.0015). For the three AR patients, MPA concentrations obtained at the time of AR revealed MPA c min values of 1.86, 1.76, and 3.83 mg/L, respectively, and MPA-AUC (0 -12) values of 37.7, 24.9, and 104.9 mg ⅐ h/L. The threshold of toxicity was 3 mg/L (sensitivity, 38.7%; specificity, 91.5%) for c min , 8.09 mg/L for maximum MPA concentration during the first hour (sensitivity, 77.8%; specificity, 67.4%), and 37.6 mg ⅐ h/L for MPA-AUC (0 -12) (sensitivity, 83.3%; specificity, 59.6%). Conclusions: These results demonstrate the relationship between plasma MPA concentrations and toxicity. High c min, c 30 , and c 60 values as well as AUC (0 -12) are associated with increased risk for side effects. These values may have an importance in a routine monitoring program.

Research paper thumbnail of Validation of a HPLC-MS/MS assay for the determination of total and unbound concentration of temocillin in human serum

Clinical biochemistry, Jan 21, 2015

The aim of this study was to develop and validate a HPLC-MS/MS assay to determine total and unbou... more The aim of this study was to develop and validate a HPLC-MS/MS assay to determine total and unbound concentrations of temocillin in serum samples. Methanolic protein precipitation and ultrafiltration were used for total and unbound concentration extraction, respectively. Extract was injected into a LC-MS/MS system. Reversed phase chromatography was performed on a phenyl grafted column in gradient mode. Temocillin and internal standard (ticarcillin) were identified in positive electrospray ionization mode using ion transitions of m/z 415.34>339.1 and 385.31>160.3, respectively. Temocillin total and unbound concentration quantification assays were linear over concentrations ranging from 1 to 500mg/L and from 0.5 to 300mg/L, respectively. Both assays presented acceptable intra and inter-assay precision and accuracy <13.9%. Limits of quantification and detection were of 1 and 0.10mg/L, and 0.5 and 0.05mg/L for total and unbound concentration respectively. Total temocillin conce...

Research paper thumbnail of par le Virus de l'immunodéfi cience humaine (VIH) et son traitement au Mali

Research paper thumbnail of Does the Russell Viper Venom time test provide a rapid estimation of the intensity of oral anticoagulation? A cohort study

Thrombosis Research, 2015

Background: Dilute Russell Viper Venom Time (DRVV-T) might be useful in urgent settings for scree... more Background: Dilute Russell Viper Venom Time (DRVV-T) might be useful in urgent settings for screening patients on Non-VKA Oral Anticoagulants (NOACs). Aim: To compare the accuracy of DRVV-T with gold standard assays for the assessment of pharmacodynamics of dabigatran, rivaroxaban and vitamin K antagonist (VKA) in plasma samples from patients. Methods: Sixty rivaroxaban, 48 dabigatran and 50 VKA samples from patients were included. DRVV-T was performed in all groups using STA ® -Staclot ® DRVV-Screen and -Confirm. For NOACs, PT and aPTT were performed using different reagents while plasma drug concentrations were measured by liquid mass-spectrometry (LC-MS/MS). For VKA, INR was performed using RecombiPlasTin 2G ® . Results: For NOACs, correlations between calibrated STA ® -Staclot ® DRVV-Confirm and LC-MS/MS (rs = 0.88 and 0.97 for rivaroxaban and dabigatran, respectively) were higher than the ones obtained with STA ® -Staclot ® DRVV-Screen (rs = 0.87 and 0.91), PT (rs = 0.83 to 0.86) or aPTT (rs = 0.84 to 0.89). Bland Altman analyses showed that calibrated DRVV-T methods tend to overestimate plasma concentrations of NOACs. ROC curves revealed that cut-off to exclude supra-therapeutic levels at C trough (i.e. 200 ng/mL) are different for dabigatran and rivaroxaban. Neither STA ® -Staclot ® DRVV-Screen nor -Confirm correlated sufficiently with the intensity of VKA therapy (rs = 0.35 and 0.52). Conclusions: STA ® -Staclot ® DRVV-Confirm provides a rapid estimation of the intensity of anticoagulation with rivaroxaban or dabigatran without specific calibrators. At C trough , thresholds for rivaroxaban and dabigatran can be used to identify supra-therapeutic plasma level. However, this test cannot differentiate the nature of the NOACs. The development of a point-of-care device optimising this method would be of particular interest in emergency situations.

Research paper thumbnail of Could trisialotransferrin be used as an additional biomarker to CDT in order to improve detection of chronic excessive alcohol intake?

Clinical Biochemistry, 2014

Carbohydrate-deficient transferrin is a well-known biomarker widely used for detection of chronic... more Carbohydrate-deficient transferrin is a well-known biomarker widely used for detection of chronic excessive alcohol intake. However, under certain clinical conditions particularly frequently met amongst heavy drinkers (steatosis, fibrosis, cirrhosis…), it isn&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;t a reliable biomarker. In this study, we tried to find additional biomarkers to CDT in order to improve detection of chronic excessive alcohol intake. We conducted a retrospective cohort study from December 2007 to December 2009. We focused mainly on three different groups: heavy drinking patients with active alcohol consumption (n=243), cirrhotic patients (abstinent patients and non alcoholic cirrhosis, n=44) and control group (n=85). In our study, CDT showed a poor sensitivity for diagnosis of heavy drinking patients (around 63%, and even lower) for cirrhotic patients and patients at advanced stage of fibrosis. Combination of CDT with trisialotransferrin enabled to improve significantly sensitivity and specificity (p-value AUC ROC&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). When adding mean corpuscular volume and gamma-glutamyltransferase to this first combination, performances were even better (p-value&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). This second cluster enabled to make a statistically significant difference between cirrhotic patients with active alcohol consumption compared to abstinent cirrhotic patients and to non alcoholic cirrhotic patients (p-value&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.001). From our study, trisialotransferrin seems to be a useful additional biomarker to CDT in order to improve detection of chronic excessive alcohol intake.

Research paper thumbnail of Ultra-high performance liquid chromatography tandem mass spectrometric method for the determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots--development, validation and clinical application during breast cancer adjuvant therapy

Talanta, 2015

A LC-MSMS method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxy... more A LC-MSMS method for the simultaneous determination of tamoxifen, N-desmethyltamoxifen, 4-hydroxytamoxifen and endoxifen in dried blood spots samples was developed and validated. The method employs an ultrasound-assisted liquid extraction and a reversed phase separation in an Acquity(®) C18 column (150×2.1 mm, 1.7 µm). Mobile phase was a mixture of formic acid 0.1% (v/v) pH 2.7 and acetonitrile (gradient from 60:40 to 50:50, v/v). Total analytical run time was 8 min. Precision assays showed CV % lower than 10.75% and accuracy in the range 94.5 to 110.3%. Mean analytes recoveries from DBS ranged from 40% to 92%. The method was successfully applied to 91 paired clinical DBS and plasma samples. Dried blood spots concentrations were highly correlated to plasma, with rs>0.83 (P<0.01). Median estimated plasma concentrations after hematocrit and partition factor adjustment were: TAM 123.3 ng mL(-1); NDT 267.9 ng mL(-1), EDF 10.0 ng mL(-1) and HTF 1.3 ng mL(-1,) representing in averag...

Research paper thumbnail of Correlation of mycophenolic acid pharmacokinetic parameters with side effects in kidney transplant patients treated with mycophenolate mofetil

Clinical chemistry, 2001

Mycophenolate mofetil (MMF) is widely used in organ transplantation to prevent acute rejection. B... more Mycophenolate mofetil (MMF) is widely used in organ transplantation to prevent acute rejection. Because MMF can produce hematologic and/or gastrointestinal toxicity, therapeutic monitoring is becoming mandatory. This study was designed to investigate the relationship between the clinical events and the pharmacokinetics of mycophenolic acid (MPA) in adult renal transplantation. Thirty-one adult kidney recipients were prospectively included in the study. MPA pharmacokinetic profiles (blood sampling at 0, 0.5, 1, 2, 4, 6, and 12 h after MMF oral dose) were obtained after transplantation (desired creatinine clearance, 40 mL/min), at 3 months after grafting, and at every clinical event (e.g., side effect or rejection). All patients received a 10-day course of anti-thymocyte globulin, cyclosporine, MMF (1 g twice daily), and steroids. We divided the 31 patients into two groups (groups 1 and 2). Ten patients (32%; group 1) had uneventful outcomes, and 21 patients (68%; group 2) presented w...

Research paper thumbnail of Is plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) determination in donors and recipients predictive of renal function after kidney transplantation?

Clinical biochemistry, 2014

Delayed graft function (DGF) is still a major issue in kidney transplantation. Plasma and urine n... more Delayed graft function (DGF) is still a major issue in kidney transplantation. Plasma and urine neutrophil gelatinase-associated lipocalin (NGAL) were evaluated in a population of kidney donors and recipients to investigate their performance to predict early renal function. Plasma (pNGAL) and urine (uNGAL) samples were obtained from donors before organ procurement, and from recipients before transplantation, and then 6, 24 and 48h after the procedure. Kidney transplantations were performed from both living donors (LDs, n=17) and deceased donors (DDs, n=80). Recovery of renal function was evaluated as the time to reach serum creatinine <2mg/l or glomerular filtration rate (GFR)>40mL/min. Logistic regression was used to assess the ability of different variables to predict the occurrence of DGF. Plasma NGAL levels were significantly lower in LDs than in DDs. No episodes of DGF were recorded among LD kidney recipients, but DGF was observed in 25% of patients in the DD group. There...

Research paper thumbnail of Modelled target attainment after meropenem infusion in patients with severe nosocomial pneumonia: the PROMESSE study

The Journal of antimicrobial chemotherapy, 2015

The objective of this study was to propose an optimal treatment regimen of meropenem in criticall... more The objective of this study was to propose an optimal treatment regimen of meropenem in critically ill patients with severe nosocomial pneumonia. Among 55 patients in intensive care treated with 1 g of meropenem every 8 h for severe nosocomial pneumonia, 30 were assigned to intermittent infusion (II; over 0.5 h) and 25 to extended infusion (EI; over 3 h) groups. Based on plasma and epithelial lining fluid (ELF) concentrations determined at steady-state, pharmacokinetic modelling and Monte Carlo simulations were undertaken to assess the probability of attaining drug concentrations above the MIC for 40%-100% of the time between doses (%T > 1-fold and 4-fold MIC), for 1 or 2 g administered by either method. Penetration ratio, measured by the ELF/plasma ratio of AUCs, was statistically higher in the EI group than in the II group (mean ± SEM: 0.29 ± 0.030 versus 0.20 ± 0.033, P = 0.047). Considering a maximum susceptibility breakpoint of 2 mg/L, all dosages and modes of infusions achi...

Research paper thumbnail of Sirolimus and Tacrolimus Trough Concentrations and Dose Requirements after Kidney Transplantation in Relation to CYP3A5 and MDR1 Polymorphisms and Steroids

Transplantation, 2005

CYP3A5 and MDR1 polymorphisms have been shown to influence tacrolimus blood concentrations and do... more CYP3A5 and MDR1 polymorphisms have been shown to influence tacrolimus blood concentrations and dose requirements. The aim is to determine whether these polymorphisms also affect sirolimus trough concentrations and dose requirements after kidney transplantation. Eighty-five renal transplant recipients receiving sirolimus were included. Twenty-four were treated with a combined sirolimus-tacrolimus regimen. Eighty-one patients received steroids. Sirolimus and tacrolimus were adjusted to a target therapeutic window. CYP3A5 (intron 3) and MDR1 (exons 12, 21, 26) genotypes were correlated to the adjusted trough concentrations and dose requirements for both sirolimus and tacrolimus. There were no significant correlation between adjusted sirolimus trough concentrations or dose requirements and genetic polymorphisms. In a multiple regression model, adjusted-prednisone dose was involved with a positive or negative effect when considering sirolimus dose requirements or adjusted concentrations, respectively. In the subgroup of patients treated by tacrolimus and sirolimus, adjusted tacrolimus doses were higher in patients carrying at least one CYP3A5 *1 allele (median 0.083 vs. 0.035 mg/kg for CYP3A5*3/*3 patients, P&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;0.05). Adjusted-prednisolone dose and CYP3A5 polymorphism explained up to 61% of the variability in tacrolimus dose requirements. Unlike tacrolimus, sirolimus adjusted trough concentrations and dose requirements seem not affected by CYP3A5 and MDR1 polymorphisms. Adjusted-prednisone dose has a significant impact on tacrolimus and sirolimus dose requirements.

Research paper thumbnail of Biotransformation Enzymes and Drug Transporters Pharmacogenetics in Relation to Immunosuppressive Drugs: Impact on Pharmacokinetics and Clinical Outcome

Transplantation, 2008

Immunosuppressive drugs commonly used after organ transplantation to prevent acute rejection incl... more Immunosuppressive drugs commonly used after organ transplantation to prevent acute rejection including tacrolimus, cyclosporine, sirolimus, and mycophenolic acid are characterized by a narrow therapeutic index and broad interindividual variability in their pharmacokinetics. Adequate immunosuppression aims to reach an optimal benefit-risk ratio. Therapeutic drug monitoring represents a crucial step in routine practice to maintain blood concentrations within the target window, because the bioavailability of these drugs depends on their absorption, distribution, biotransformation, and elimination. Single nucleotide polymorphisms (SNPs) in genes encoding biotransformation enzymes (CYP3A) and drug transporters (ABCB1) have opened up a promising way for the selection of individual dosages. The relationship of these SNPs with immunosuppressive drug pharmacokinetics was extensively studied after kidney, liver, heart, and lung transplantations. Patient susceptibility to nephrotoxicity in the long term was also reported in relation to some SNPs, which could allow effective assessment of individual risk and selection of treatment according to patient parameters. Further studies are needed to provide evidence that a genetic analysis combined with therapeutic drug monitoring has the potential to optimize drug use after transplantation.

Research paper thumbnail of CONVERSION FROM CYCLOSPORINE TO FK506 FOR SALVAGE OF IMMUNOCOMPROMISED PEDIATRIC LIVER ALLOGRAFTS EFFICACY, TOXICITY, AND DOSE REGIMEN IN 23 CHILDREN

Transplantation, 1994

Twenty-three pediatric liver transplant recipients (median age 3.9 years) were converted from cyc... more Twenty-three pediatric liver transplant recipients (median age 3.9 years) were converted from cyclosporine A-based immunosuppression to FK506 for uncontrollable acute rejection (AR; n = 16), chronic rejection (n = 4), or predominantly nonspecific hepatitis (n = 3). Of these, 19 had received poly- or monoclonal anti-T lymphocyte antibodies either for AR prophylaxis or therapy before FK506 conversion. Full clinical and histologic responses to FK506 therapy were observed in 11/16 cases of AR compared with 0/7 cases of non-AR indications (P = 0.006). Acute FK506 toxicity included renal dysfunction in 12/23 children (52%), neurological disorders in 7/23 (30%), and isolated hyperkalemia in 2/23 (9%), with a poor correlation with the corresponding FK506 trough plasma level. Moreover, a significant impairment of glomerular filtration rate was recorded in the 12 children who received FK506 treatment for more than 6 months (P = 0.002). FK506 therapy had to be definitively withdrawn in 6 cases (fatal infections: n = 4; persistent tremor: n = 1; reason unrelated to FK506: n = 1). Five children developed a lymphoproliferative syndrome (LPS), leading to death in 3 cases despite cessation of the immunosuppressive therapy; in the other 2 patients, LPS was controlled, and the children were successfully retransplanted for chronic rejection under FK506. The occurrence of Epstein-Barr virus primary infection under FK506 therapy was found to constitute a significant risk factor for LPS (P = 0.027). In summary, full response to FK506 conversion was observed in 69% of uncontrollable AR cases; however, 74% and 22% of this probably over-immunosuppressed population experienced major adverse events and LPS under FK506 therapy, respectively.

Research paper thumbnail of EARLY HEPATOCYTE, ENDOTHELIAL, AND BILE DUCT CELL INJURY AFTER PEDIATRIC LIVER TRANSPLANTATION FROM CADAVERIC OR LIVING-RELATED DONORS

Transplantation, 1998

Background. When compared with cadaveric grafts (Cad), the potential advantages of pediatric orth... more Background. When compared with cadaveric grafts (Cad), the potential advantages of pediatric orthotopic liver transplantation (OLT) from living-related (LR) donors may include better graft quality, shorter ischemic time, appropriate preparation of the recipient, and better immunologic compatibility.

Research paper thumbnail of Clinical pharmacokinetics of Neoral in pediatric recipients of primary liver transplants

Transplant International, 1997

Pediatric liver transplant recipients constitute a population characterized by a particularly unp... more Pediatric liver transplant recipients constitute a population characterized by a particularly unpredictable and poor bioavailability of cyclosporin (CyA). Even though several adult studies show that the new oral formulation of CyA, Neoral (NEO), produces better bioavailability and blood level predictability, few data describe its pharmacokinetics in children. We performed a complete analysis of the pharmacokinetics of NEO in ten small children after primary liver transplantation. Three pharmacokinetic profiles were set up with data obtained from tests taken during i. v. administration of CyA, after the first oral NEO dose, and after the last NEO dose before discharge from the hospital. The mean halflives obtained were 8.1, 7.7, and 6.9 h, respectively, and the bioavailabilities were 22 YO and 21 % for the first and last NEO doses. A large in-

Research paper thumbnail of Endoxifen Levels and Its Association With CYP2D6 Genotype and Phenotype

Therapeutic Drug Monitoring, 2012

Background: An association between CYP2D6 variation and clinical outcomes among women with breast... more Background: An association between CYP2D6 variation and clinical outcomes among women with breast cancer treated with tamoxifen (TAM) has been demonstrated, such that the presence of 2 functional CYP2D6 alleles was associated with better clinical outcomes. This association is mainly due to the CYP2D6-mediated hydroxylation of N-desmethyltamoxifen (NDT) to yield endoxifen (EDF), which because of its high antiestrogenic potency, is mainly responsible for the therapeutic efficacy of TAM. The aim of this study was to evaluate the relation of CYP2D6 genotyping and phenotyping with EDF levels and [NDT]/[EDF] metabolic ratio in breast cancer patients from South of Brazil under TAM therapy.

Research paper thumbnail of Opportunities to Optimize Tacrolimus Therapy in Solid Organ Transplantation: Report of the European Consensus Conference

Therapeutic Drug Monitoring, 2009

In 2007, a consortium of European experts on tacrolimus (TAC) met to discuss the most recent adva... more In 2007, a consortium of European experts on tacrolimus (TAC) met to discuss the most recent advances in the drug/dose optimization of TAC taking into account specific clinical situations and the analytical methods currently available and drew some recommendations and guidelines to help clinicians with the practical use of the drug. Pharmacokinetic, pharmacodynamic, and more recently pharmacogenetic approaches aid physicians to individualize long-term therapies as TAC demonstrates a high degree of both between- and within-individual variability, which may result in an increased risk of therapeutic failure if all patients are administered a uniform dose. TAC has undoubtedly benefited from therapeutic drug monitoring, but interpretation of the blood concentration is confounded by the relative differences between the assays. Single time points, limited sampling strategies, and area under concentration-time curve have all been considered to determine the most appropriate sampling procedure that correlates with efficacy. Therapeutic trough TAC concentration ranges have changed since the initial introduction of the drug, while still maintaining adequate immunosuppression and avoiding drug-related adverse effects. Pharmacodynamic markers have also been considered advantageous to the clinician, which may better reflect efficacy and safety, taking into account the between-individual variability rather than whole blood concentrations. The choice of method, differences between methods, and potential pitfalls of the method should all be considered when determining TAC concentrations. The recommendations of this consensus meeting regarding the analytical methods include the following: encourage the development and promote the use of analytical methods displaying a lower limit of quantification (1 ng/mL), perform careful validation when implementing a new analytical assay, participate in external proficiency testing programs, promote the use of certified material as calibrators in high-performance liquid chromatography with mass spectrometric detection methods, and take account of the assay and intermethod bias when comparing clinical trial outcomes. It is also important to consider that TAC concentrations may also be influenced by other factors such as specific pharmacokinetic characteristics associated with the population, drug interactions, pharmacogenetics, adverse events that may alter TAC concentrations, and any change in the oral formulation that may result in pharmacokinetic changes. This meeting emphasized the importance of obtaining multicenter prospective trials to assess the efficacy of alternative strategies to TAC trough concentrations whether it is other single time points or area under the concentration-time curve Bayesian estimation using limited sampling strategies and to select, standardize, and validate routine biomarkers of TAC pharmacodynamics.

Research paper thumbnail of Multi-site Analytical Evaluation of the Abbott ARCHITECT Tacrolimus Assay

Therapeutic Drug Monitoring, 2009

The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Ta... more The objective of this study was to evaluate the analytical performance of the Abbott ARCHITECT Tacrolimus immunoassay. Proficiency panels and specimens from a population of organ transplant recipients were analyzed in 6 clinical laboratories in Europe and the United States, and the results were compared with other methods. The ARCHITECT assay requires a whole blood specimen pretreatment step with methanol/zinc sulfate to precipitate protein and extract the drug, followed by a 30-minute immunoassay using anti-tacrolimus antibody-coated paramagnetic microparticles and an acridinium-tacrolimus tracer. The assay was free from hematocrit interference in the range 25%-55% and from interference by extremes of cholesterol, triglycerides, bilirubin, total protein, and uric acid. The total percent of coefficient of variations of the assay were 4.9%-7.6% at 3 ng/mL, 2.9%-4.6% at 8.6 ng/mL, and 3.1%-8.2% at 15.5 ng/mL. Limit of detection was &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; or =0.5 ng/mL and limit of quantification (LOQ) ranged from 0.69 to 1.07 ng/mL across the 6 sites (based on the upper 95% confidence interval concentrations). The 2007 European Consensus Conference on Tacrolimus Optimization recommended the use of assay methods with an LOQ around 1 ng/mL, based upon the need to measure trough tacrolimus blood concentrations precisely down to 3 ng/mL during low-dose tacrolimus regimens. Tacrolimus International Proficiency Testing Scheme samples were measured by the ARCHITECT immunoassay at 5 sites and showed an average bias of -0.28 to +0.85 ng/mL versus IMx Tacrolimus II immunoassay historical values and -0.21 to +0.68 ng/mL versus liquid chromatography/tandem mass spectrometry (LC-MSMS) Tacrolimus historical values. Method comparison studies were performed with the ARCHITECT Tacrolimus immunoassay on patient specimens with the following results: ARCHITECT Tacrolimus assay versus the Abbott IMx Tacrolimus II immunoassay (4 sites) yielded average biases between -0.94 and +0.26 ng/mL; ARCHITECT assay versus the Dade Dimension Tacrolimus immunoassay (2 sites) yielded average biases of -0.46 and +0.11 ng/mL; and ARCHITECT assay versus LC-MSMS methods at 2 sites yielded average biases of +0.51 and +1.63 ng/mL. Spearman correlation coefficients were &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;/=0.90 on all method comparisons. The ARCHITECT Tacrolimus assay is a semiautomated, robust, and highly sensitive immunoassay, representing an alternative approach for laboratories not equipped with LC-MSMS, and meets the 1 ng/mL recommendation of LOQ by the European Consensus Conference on Tacrolimus Optimization.

Research paper thumbnail of Increased Tissue Arachidonic Acid and Reduced Linoleic Acid in a Mouse Model of Cystic Fibrosis Are Reversed by Supplemental Glycerophospholipids Enriched in Docosahexaenoic Acid

Journal of Nutrition, 2009

An imbalance in (n-6)/(n-3) PUFA has been reported in cystic fibrosis (CF) patients. Glycerophosp... more An imbalance in (n-6)/(n-3) PUFA has been reported in cystic fibrosis (CF) patients. Glycerophospholipids enriched in docosahexaenoic acid (GPL-DHA) have been shown to regulate the (n-6)/(n-3) fatty acid ratio in the elderly. Here, we tested the effect of GPL-DHA supplementation on PUFA status in F508del homozygous CF mice. GPL-DHA liposomes were administrated by gavage (60 mg DHA/kg daily, i.e. at maximum 1.4 mg DHA/d) to 1.5-mo-old CF mice (CF+DHA) and their corresponding wild-type (WT) homozygous littermates (WT+DHA) for 6 wk. The PUFA status of different tissues was determined by GC and compared with control groups (CF and WT). There was an alteration in the (n-6) PUFA pathway in several CF-target organs in CF compared with WT mice, as evidenced by a higher level of arachidonic acid (AA) in membrane phospholipids or whole tissue (21 and 39% in duodenum-jejunum, 32 and 38% in ileum, and 19 and 43% in pancreas). Elevated AA levels were associated with lower linoleic acid (LA) and higher dihomo-g-linolenic acid levels. No DHA deficiency was observed. GPL-DHA treatment resulted in different PUFA composition changes depending on the tissue (increase in LA, decrease in elevated AA, DHA increase, increase in (n-6)/(n-3) fatty acid ratio). However, the DHA/ AA ratio consistently increased in all tissues in CF+DHA and WT+DHA mice. Our study demonstrates the effectiveness of an original oral DHA formulation in counter-balancing the abnormal (n-6) fatty acid metabolism in organs of CF mice when administrated at a low dose and highlights the potential of the use of GPL-DHA as nutritherapy for CF patients. J. Nutr.

Research paper thumbnail of CYP3A5 and ABCB1 polymorphisms influence tacrolimus concentrations in peripheral blood mononuclear cells after renal transplantation

Pharmacogenomics, 2010

This prospective study investigated the effect of genetic polymorphisms in a biotransformation en... more This prospective study investigated the effect of genetic polymorphisms in a biotransformation enzyme (CYP3A5) and a transporter protein (ABCB1) on tacrolimus (Tac) whole blood concentrations in renal transplantation, and more specifically on peripheral blood mononuclear cell (PBMC) drug concentrations, after renal transplantation. A total of 96 renal transplant recipients were genotyped for the exon 11 (1199G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;A), 21 (3435C&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T) and 26 (2677G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T/A) polymorphisms in the ABCB1 gene and for the intron 3 polymorphism in the CYP3A5 gene. Tac blood and PBMC concentrations were determined at day 7 after transplantation and at steady state, and then compared with recipient genotypes. The ABCB1 1199G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;A, 3435C&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T and 2677G&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;T/A SNPs, appeared to reduce the activity of P-glycoprotein towards Tac, increasing Tac PBMC concentrations. The impact of ABCB1 genetic polymorphisms on Tac blood concentrations was negligible. As increased Tac intracellular concentrations might in turn enhance immunosuppressive status and prevention or rejection, ABCB1 recipient genotyping might be useful to better individualize the Tac immunosuppressive therapy in renal transplantation.