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Background: Therapeutic drug monitoring of mycophenolic acid (MPA) is usually performed with a limited sampling strategy (LSS), which relies on a limited number of blood samples and subsequent extrapolation of the global exposure to MPA. LSS is usually performed successfully with mycophenolate mofetil (MMF), but data on enteric-coated mycophenolate sodium (EC-MPS) are scarce. Here, we evaluated the feasibility of 6-h LSS therapeutic drug monitoring with EC-MPS compared with MMF monitoring among kidney transplant recipients., Methods: Sixty-two patients who received EC-MPS during the first 6 months of transplantation were compared with a matched group of 64 MMF-treated kidney transplant recipients. The area under the curve (AUC) was computed by LSS using multiple concentration time points (0, 1, 2, 3 and 6 h post-dose) and a trapezoidal rule. Patients had MPA therapeutic drug monitoring performed on two occasions, one within 2 weeks and the second after 3-4 months of transplantation., Results: EC-MPS monitoring and MMF therapeutic drug monitoring were not interpretable in 34.5% (n = 40/116) and 1.8% (n = 2/112) of patients, respectively {relative risk [RR] 19.3 [95% confidence interval (CI) 4.8-78.0]; P < 0.0001}. The main cause of abnormal EC-MPS therapeutic drug monitoring was delayed absorption of both the previous evening and the morning dose, resulting in MPA plasma levels before the next morning dose being higher than MPA plasma levels measured at 1, 2 and 3 h after taking EC-MPS. Cyclosporin in association with MMF significantly increased the risk of low AUC values (<30 mg h/L) in comparison with tacrolimus [55% (n = 11/20) and 10% (n = 9/88), respectively; RR 5.4 (95% CI 2.6-11.2); P < 0.0001]., Conclusions: The risk of therapeutic drug monitoring failure with EC-MPS is >30% during the first 6 months of renal transplantation. Delayed pharmacokinetics was the main reason. In contrast, the risk of therapeutic drug monitoring failure was substantially lower with MMF.

Membranous nephropathy (MN) is the most common cause for nephrotic syndrome in adults and occurs as an idiopathic (primary) or secondary disease. Since the early 2000's, substantial advances have been made in the understanding of the molecular bases of MN. The neutral endopeptidase (NEP) and the receptor for secretory phospholipase A2 (PLA2R) have been identified as target antigens for circulating and deposited antibodies in allo-immune neonatal and adult " idiopathic " MN, respectively. These antibodies recognize specific antigens of podocytes, precipitate as subepithelial immune complexes and activate complement leading to proteinuria. Anti-PLA2R antibodies are of particular clinical importance. Indeed, they are detected in approximately 70% of primary MN in adults, demonstrating that MN actually is an autoimmune condition specific to the kidney. In Europeans, genome-wide studies have shown an association between alleles of PLA2R1 and HLA DQA1 (class II genes of tissue histocompatibility complex) genes and idiopathic MN. Newly developed diagnostic tests detecting circulating anti-PLA2R antibody and PLA2R antigen in glomerular deposits have induced a change in paradigm in the diagnostic approach of idiopathic MN. Measurement of circulating anti-PLA2R antibody is also very useful for the monitoring of MN activity. However, the mechanisms responsible for the formation of anti-PLA2R antibodies as well as those involved in the progression of MN to end-stage renal disease remain to be defined.

Intravesical instillation of bacillus Calmette-Guerin (BCG) is the treatment of choice for non-muscle-invasive bladder cancer (NMIBC) of high grade and/or carcinoma in situ. This study evaluated the feasibility, efficacy, and tolerance of BCG instillations in eight kidney recipients for end-stage aristolochic acid nephropathy (AAN), a condition at high risk of urothelial carcinoma, and diagnosed for NMIBC. Five of them had relapsed after mitomycin C treatment. Tolerance to BCG was evaluated clinically and regular follow-up with fluorescence cystoscopy was performed along with renal graft function monitoring. Immunosuppression doses were adjusted and prophylactic anti-tuberculous treatment given to reduce risks of graft rejection and infection. After a mean follow-up period of 50 months, seven of the eight patients are free of relapse and kidney graft function remained unchanged. Tolerance was good, except for one episode of fever and one early discontinuation because of subjective discomfort. No systemic tuberculous infection was observed. This is the first clinical observation of successful BCG therapy for NMIBC in patients given transplant for end-stage AAN. Under standardized conditions, immunotherapy based on intravesical BCG is feasible, effective, and well tolerated in renal transplantation., (© 2014 Steunstichting ESOT.)

Background. Although numerous risk factors for delayed graft function (DGF) have been identified, the role of ischemia-reperfusion injury and acute rejection episodes (ARE) occurring during the DGF period is ill-defined and DGF impact on patient and graft outcome remains controversial. Methods. From 1983 to 2014, 1784 kidney-only transplantations from deceased donors were studied. Classical risk factors for DGF along with two novel ones, recipient's perioperative saline loading and residual diuresis, were analyzed by logistic regression and receiver operating characteristic (ROC) curves. Results. Along with other risk factors, absence of perioperative saline loading increases acute rejection incidence (OR = 1.9 [1.2-2.9]). Moreover, we observed two novel risk factors for DGF: patient's residual diuresis ≤500 mL/d (OR = 2.3 [1.6-3.5]) and absence of perioperative saline loading (OR = 3.3 [2.0-5.4]). Area under the curve of the ROC curve (0.77 [0.74-0.81]) shows an excellent discriminant power of our model, irrespective of rejection. DGF does not influence patient survival (P = 0.54). However, graft survival is decreased only when rejection was associated with DGF (P < 0.001).  Conclusions. Perioperative saline loading efficiently prevents ischemia-reperfusion injury, which is the predominant factor inducing DGF. DGF per se has no influence on patient and graft outcome. Its incidence is currently close to 5% in our centre.

Background: Patients undergoing kidney transplantation are sometimes being treated with antiplatelet agents such as ticlopidine or clopidogrel. Some teams refuse to wait-list these patients for fear of bleeding during transplant surgery., Methods: We retrospectively reviewed the records of 702 adult patients with a kidney transplant alone between 2000 and 2010. Nineteen (2.7%) patients were taking clopidogrel or ticlopidine when called in for transplantation. Furthermore, 10 of these 19 patients were also taking low-dose aspirin (ASA). We compared the risk of bleeding peri- and postoperatively, and the occurrence of cardiovascular complications within 30 days after renal transplantation between 19 cases and 39 controls randomly selected within the cohort., Results: Platelets were administered to 7 cases (37%) versus 0 controls (P<0.001). A single case (5.3%) presented with significant bleeding during surgery following an implantation biopsy, and required 4 red bood cell (RBC) units. During the first day, 3 of the 19 cases (16%) and 1 of the 39 controls required RBC (P=0.1). No reoperation was performed for bleeding. After the transplant, clopidogrel or ticlopidine was resumed in only two patients. The platelet count and haemoglobin were similar between cases and controls at Day 30. No cardiovascular event occurred in cases or controls during the first month post-transplantation. At 5 years, graft and patient survival was similar in cases and controls., Conclusions: Clopidogrel and ticlopidine, sometimes in combination with ASA, are associated with a low risk of bleeding during renal transplantation and does not seem to be a contraindication for renal transplant surgery.

Background: Several studies suggest that the introduction of tacrolimus (TRL), mycophenolic acid (MPA) and interleukin 2 receptor antibodies (IL2Ra) as single drugs more than a decade ago has not increased the risk of malignancy after renal transplantation. However, only limited data are available on their carcinogenic effects when used in combination as a potent immunosuppressive regimen., Methods: A retrospective single-centre cohort study on 929 adult renal transplant recipients. Investigation of the effect of two consecutive immunosuppressive regimens [1993-98, N = 405, anti-lymphocyte antibodies, cyclosporine and azathioprine (AZA); 1999-2007, N = 524, predominantly IL2Ra, TRL and MPA] on the incidence rate of skin cancer, solid tumours and post-transplant lymphoproliferative disease (PTLD)., Results: In total, 365 malignancies developed among 113 patients. As compared to the previous cyclosporine and AZA-based immunosuppression, the introduction of the new immunosuppressive regimen did not increase the incidence rate of skin cancer [rate ratio 0.84; 95% confidence interval (CI) 0.48-1.46], solid tumours (0.89; 95% CI 0.46-1.67) and PTLD (0.82; 95% CI 0.28-2.21). Patients treated with the more recent regimens less frequently developed multiple skin cancers and invasive squamous cell cancer. Skin cancer after transplantation was strongly associated with the development of solid tumours (odds ratio 5.2; P < 0.0001). The introduction of the new immunosuppressive drugs reduced the incidence of first year acute rejection from 34.8 to 13.2% (P < 0.0001)., Conclusion: Although significantly more efficient in the prevention of acute rejection, the introduction of TRL, MPA and IL2Ra-based immunosuppression after kidney transplantation was not associated with an increased incidence of skin cancer, solid tumours or PTLD.

Background: The aim of our study was to evaluate the prevalence of acquired thrombophilic factors in Stage V chronic kidney disease (CKD) patients according to dialysis modality, the rate of correction of these factors 1 month after renal transplantation and their impact on cardiovascular or thromboembolic events at 1 year., Methods: Three hundred and ten patients were prospectively screened for seven thrombophilic factors at transplantation; 215 of them were also assayed 1 month after. All the patients received prophylactic acetylsalicylic acid, started before transplantation., Results: The prevalence of thrombophilic factors was significantly higher in patients under dialysis (n = 289) than in patients not yet on dialysis (n = 21) (74 versus 52.4%; P = 0.03) but was similar in haemodialysis and peritoneal dialysis patients (74.2 versus 73.2%). One month after transplantation, the global prevalence of thrombophilic factors had dropped from 74.4 to 44.7% (P < 0.001). Most thrombophilic factors had disappeared after transplantation: antithrombin deficiency: 13.5 versus 0.9%; P < 0.001, protein C deficiency: 12.1 versus 1.9%; P < 0.001, protein S deficiency: 3.7 versus 1.4%; P = 0.1, lupus anticoagulant: 37.7 versus 8.4%; P < 0.001 and antiphospholipid antibodies: 29.3 versus 12.6%; P < 0.001. The prevalence of activated protein C resistance, which reflects inherited factor V (FV) Leiden, was unchanged (1.9%), while the prevalence of elevated factor VIIIc increased from 20.9 to 30.7%, P < 0.001. The incidence of cardiovascular or thromboembolic events 1 year after transplantation was similar in patients with more than or equal to one thrombophilic factor at 1 month (5.2%) versus thrombophilic-free patients (6.7%)., Conclusion: Acquired thrombophilic factors are highly prevalent among Stage V CKD patients. Most thrombophilic factors are corrected 1 month after transplantation.

Background: Advagraf is a slow release form of tacrolimus with once-daily formulation. The potential advantages of Advagraf are better adherence and a safer profile by avoiding toxic peak concentrations. In this study, we evaluated the required daily doses of tacrolimus and subsequent blood levels on conversion from Prograf to Advagraf among kidney transplant recipients., Methods: We retrospectively reviewed data from 55 patients for whom a switch from Prograf to Advagraf was identified. Tacrolimus daily doses and concomitant blood levels were analyzed at several time points ranging from 3 months before to 6 months after conversion., Results: We observed a significant increase in tacrolimus daily doses, starting with a dose of 0.063 mg/kg of Prograf, increasing up to 0.081 mg/kg of Advagraf at 6 months (P<0.0001). After conversion, we observed a quick and sustained decrease in trough tacrolimus levels, decreasing from 8.05 ng/mL at day 0 to 6.30 ng/mL at day 180 (P=0.0009). At 6 months, 35% of patients experienced a decrease in trough levels of more than 30%. Creatinine values remained stable over time, and no patient experienced an acute rejection episode., Conclusions: Contrary to the manufacturer instructions, we found a significant decrease in tacrolimus exposure after switching to Advagraf. Therefore, the switch from Prograf to Advagraf should be performed under close medical supervision.

The results and risk factors within a cohort of 1.380 renal allografts treated with a calcineurin inhibitor from 1983 to 2008 at Erasme Hospital were analyzed. Three groups corresponding to successive periods were compared: A, from 1983 to 1992 (n = 463); B, from 1993 to 2000 (n = 470); C, from 2001 to 2008 (n = 447). Patient's survival was lower during period C than during periods A and B (89 vs 85% at 8 years, P = 0,044), due to the recipients age. In contrast, graft survival raised gradually (64, 76 and 81% at 8 years for periods A, B and C respectively, P < 0,001). Several factors significantly influence graft survival: in decreasing order, they are the recipient's age (reduced risk of rejection with age), immunosuppressive protocol (superiority of mycophenolate mofetyl and induction with antibodies directed to the IL2 receptor), HLA sensitization, number of HLA-B+Dr mismatches between recipient and donor, and gender (opposite effects of recipient's and donor's gender). The permanent evaluation of results using multivariate analyses would allow to promptly adapt selection and therapeutic strategies within each transplantation center.

Background: The aim of our study was to examine, in a recent cohort of kidney transplant recipients who have received modern immunosuppressive therapy, the respective role of cold ischemia time (CIT) and delayed graft function (DGF) on acute rejection (AR) rates and long-term graft survival., Methods: We retrospectively reviewed the charts of 611 renal transplantations between 1996 and 2005. Most patients received a calcineurin inhibitor as maintenance therapy, either cyclosporine (43%) or tacrolimus (52%) and 76% of the patients received an antilymphocyte induction therapy. Study endpoints were DGF, first-year AR, and long-term graft survival. Uni- and multivariate analyses were performed to determine factors that may have influenced the study outcomes., Results: DGF was observed in 16.2% of patients. Both older donor age and longer CIT were significant risk factors for DGF. DGF rates were similar whether patients received a calcineurin inhibitor before transplantation or not. AR occurred in 16.5% of grafts during the first year. Independent predictors of AR by multivariate analysis were duration of dialysis, CIT, current panel-reactive lymphocytotoxic antibody more than 5%, and the number of human leukocyte antigen-A, B, and DR mismatches. Each hour of cold ischemia increases the risk of rejection by 4%. With respect to death-censored graft survival, three pretransplant parameters emerged as independent predictors of graft loss: younger recipient age, peak panel-reactive lymphocytotoxic antibody more than 5% and longer CIT. The detrimental effect of CIT on graft survival was entirely because of its propensity to trigger AR. When AR was added to the multivariate Cox model, CIT was no longer significant whereas first-year AR became the most important predictor of graft loss (Hazards ratio, 4.6)., Conclusion: Shortening CIT will help to decrease not only DGF rates but also AR incidence and hence graft loss. Patients with prolonged CIT should receive adequate immunosuppression, possibly with antilymphocyte preparations, to prevent AR occurrence.

Background: New immunosuppressive drugs such as anti-interleukin-2 receptor antibodies (aIL2R) and mycophenolate mofetil (MMF) have reduced the incidence of acute rejection after renal transplantation. Whether matching donor and recipient human leukocyte antigen (HLA) antigens is still relevant in patients receiving modern immunosuppression has been questioned., Methods: We retrospectively analyzed the incidence and risk factors of acute rejection during the first posttransplant year and the impact of acute rejection on long-term graft survival in a cohort of 208 renal transplant patients treated with aIL2R (basiliximab, n=166; daclizumab, n=42), calcineurin inhibitors (tacrolimus, n=180; cyclosporin, n=28), mycophenolate mofetil, and steroids. Graft and patient survival were calculated by the Kaplan-Meier method. Risk factors for acute rejection were analyzed by logistic regression modeling., Results: Twenty-seven patients were treated for acute rejection (26 biopsy-proven) during the first posttransplant year. The Kaplan-Meier estimate of first-year acute rejection was 13.2%. The number of HLA mismatches (odds ratio [OR] 1.65 per HLA mismatch) and long periods of dialysis before transplantation (OR 3.1 for more than 4 years of dialysis) were the only independent risk factors for first-year acute rejection. First-year acute rejection was associated with a significant reduction in overall and death-censored graft survival at 5 years after transplantation., Conclusions: Although infrequent in patients receiving modern immunosuppressive drugs, acute rejection remains an important risk factor for graft loss after renal transplantation. Our results suggest that better HLA matching and shorter periods of dialysis before transplantation could reduce acute rejection rates and further improve outcomes under current immunosuppressive regimens.

Tacrolimus (TRL) increases the incidence of new-onset diabetes mellitus after transplantation (NODAT). Little is known about whether conversion from TRL to cyclosporine A (CsA) improves glucose metabolism in patients with NODAT. We retrospectively analysed glucose metabolism parameters in 54 TRL-treated renal transplant patients who developed NODAT. Thirty-four were converted to CsA whereas 20 patients continued TRL. After conversion, fasting plasma glucose decreased from 146 +/- 64 to 104 +/- 20 mg/dl (P < 0.0001) and HbA1c levels decreased from 6.8 +/- 0.8% to 6.0 +/- 0.6% (P < 0.0001) after 1 year of follow-up. The remission rate of NODAT reached 42% (95% confidence interval 24-59%) 1 year after conversion versus 0% in the control group (P = 0.001). Blood pressure and lipid levels were stable after conversion although the use of statins significantly increased (P < 0.01). The conversion was safe in terms of graft function and acute rejection episodes. The 1-year patient survival and graft survival rate were 100%. In conclusion, our results suggest a significant improvement of glucose metabolism after conversion to CsA in renal transplant patients with NODAT.

Since 1965, more than 2000 renal transplantations (including more than 100 living-donor transplantations) have been performed at the University of Brussels. An end-stage renal disease patient candidate to renal transplantation will be therefore followed from his enrolment on the waiting list to the long-term post-transplant period. Improvement in the outcome of renal transplantation is achieved due to better knowledge in many fields of medicine, such as immunology, infectious disease, metabolic diseases (hyperlipemia, diabetes mellitus), pharmacology, use of immunosuppressive regimen, a more adequate cardiovascular prevention and treatment. If the best results were achieved with kidneys from living donors, the graft survival rate at the University of Brussels was nearly 80% for the last period (2000-2006). Unfortunately, renal transplantation cannot cure certain comorbid conditions and even may promote them: infectious diseases, neoplasia, metabolic disorders (e.a diabetes mellitus, hyperlipemia). Many efforts have to be done to develop less toxic and more immune selective therapeutic strategies. Living donation and extension of the pool of cadaveric donors will reduce the length of time spent on the waiting list and will significantly impact on mortality and morbidity after kidney transplantation.

Background: Hypercholesterolemia is a frequent complication in renal transplant patients treated with cyclosporine A (CsA). Whether it is preferable to treat hypercholesterolemia with statins or to switch patients from CsA to tacrolimus (TRL) has not been investigated., Methods: Twelve CsA-treated kidney transplant recipients with hypercholesterolemia were successively crossed over from CsA alone to: CsA plus atorvastatin; TRL alone; and TRL plus atorvastatin. Total cholesterol (C), Low density lipoprotein (LDL)-C, high density lipoprotein (HDL)-C, LDL and HDL alpha-tocopherol content, lag-time of LDL oxidation, plasma levels of oxidized LDL and the percentage of small dense LDL were assayed at the end of each treatment period. Endothelial function was assessed by high resolution ultrasound measurement of flow-mediated brachial artery vasodilatation (FMD)., Results: Atorvastatin therapy was more efficient in reducing total cholesterol and LDL-C levels than conversion from CsA to TRL. Combining TRL with atorvastatin further reduced LDL-C levels as compared to TRL alone, but was no more efficient than the CsA-statin combination. Neither atorvastatin therapy nor conversion to TRL significantly changed the proportion of dense LDL, lipoprotein alpha-tocopherol contents or the lag time of LDL oxidation. Addition of atorvastatin to CsA increased FMD from 4.0+/-1.8% to 6.5+/-4.0% (P<0.05 vs. CsA). Conversion from CsA to TRL caused a slight improvement in FMD (5.1+/-2.1%, P<0.05 vs. CsA). Adding atorvastatin to TRL had no detectable effect on FMD (5.5+/-2.3%, P=NS vs. TRL)., Conclusions: Atorvastatin was more efficient in reducing total and LDL cholesterol levels of CsA-treated renal transplant patients than conversion to TRL and significantly improved endothelial dysfunction.

Background: New and potent immunosuppressive regimens allow for reduced doses of corticosteroids after renal transplantation. The aims of our study were to investigate whether the use of low-dose corticosteroids is associated with a reduction in posttransplant bone loss and to assess the ability of cholecalciferol supplementation to further decrease bone loss in this setting., Methods: Ninety patients admitted for renal transplantation and scheduled to be treated per protocol with low doses of prednisolone were randomized to receive either 400 mg daily oral calcium (Ca group, n=44) or the same dose of calcium in association with a monthly dose of 25,000 IU of vitamin D3 (CaVitD group, n=46). Bone mineral density (BMD) was measured by dual energy absorptiometry at baseline and at 1 year., Results: The overall population experienced a moderate but significant -2.3+/-0.9% loss of lumbar spine BMD (P<0.01) but no bone loss at the femoral neck and shaft during the first posttransplant year. Bone loss tended to be slightly higher in the CaVitD group, but the difference did not reach statistical significance. Patients in the CaVitD group had significantly higher 25(OH) but not 1,25(OH)2 vitamin D levels. We observed a highly significant negative correlation between 25(OH) vitamin D and intact parathyroid hormone (iPTH) serum levels., Conclusions: Kidney-transplant recipients receiving modern immunosuppressive regimens with low doses of corticosteroids experience only minimal loss of BMD during the first posttransplant year. Cholecalciferol supplementation did not prevent posttransplant bone loss but contributed to the normalization of iPTH levels after renal transplantation.

The Department of Nephrology of the Hospital Erasme, opened 25 years ago, is now performing, each year, 22,000 hemodialysis sessions, 800 patient-weeks of peritoneal dialysis treatment and 70 renal grafts. Scientific contributions of the department deal with vascular access for hemodialysis, susceptibility to infections of dialyzed patients, parathyroid surgery, biocompatibility of dialysis membranes, predictive factors of renal graft survival, immunosuppression with monoclonal antibodies, experimental studies of graft tolerance and rejection, toxic nephropathies. The most original contributions are related to anaphylactoïd reactions in hemodialysis by association of acrylonitrile membranes with inhibition of the converting enzyme, to advantages and side effects of OKT3 monoclonal antibody and to discovery and study of the Chinese herbs nephropathy.

Background: Whereas acute rejection is the main risk factor for the occurrence of chronic rejection, mechanisms in addition to the donor-specific immune response probably contribute to late allograft failure. In this study, we investigated the possible role of hypercholesterolemia in the incidence of chronic kidney graft loss., Methods: By using the actuarial method, we retrospectively analyzed the long-term loss of cadaveric kidney grafts in patients who had a functioning graft at 1 year and had received a transplant and undergone cyclosporin A therapy in our center between 1983 and 1997., Results: As observed previously, patients with acute rejection during the 1st posttransplant year (n=198) had significantly higher actuarial graft loss at 10 years compared with those free of acute rejection (n=244). In patients free of acute rejection at 1 year, hypercholesterolemia (> or =250 mg/dl) had no impact on graft loss at 10 years. On the contrary, in patients with previous acute rejection, those with hypercholesterolemia (n=59) had a higher immunological (36.0% vs. 19.2%; P<0.01) and overall (50.0% vs. 25.3%; P<0.01) graft loss at 10 years compared with patients with serum cholesterol <250 mg/dl (n=139). Among patients with 1st year acute rejection, hypercholesterolemia was associated with a significant increase in graft loss in male but not in female recipients. Multivariate analysis confirmed that hypercholesterolemia was an independent risk factor for chronic graft loss in male patients (P<0.05)., Conclusion: Hypercholesterolemia is an independent risk factor for kidney graft loss from chronic rejection in male patients with previous acute rejection. Correction of hypercholesterolemia could help to reduce kidney graft loss caused by chronic rejection in this category of patients.

Objective: Serious discrepancies between glycemia measurements obtained with an Accutrend Sensor (Boehringer Mannheim GmbH, Mannheim, Germany) type analyzer (based on a glucose dehydrogenase enzymatic reaction) and measurements obtained in the laboratory by a reference method (hexokinase) have been found in an insulin-requiring, diabetic, continuous ambulatory peritoneal dialysis (CAPD) patient treated with icodextrin 7.5% (Extraneal; Baxter Healthcare SA, Castlebar, Ireland), a new osmotic agent for peritoneal dialysis. We therefore investigated the respective role of the Analyzer and of the glucose polymer in this hitherto undescribed problem., Design: Glycemia was measured simultaneously on venous blood using a reference laboratory technique, and on capillary blood using the Accutrend Sensor glucose analyzer in three groups of CAPD patients: 6 patients on Extraneal for at least 1 week, 6 patients receiving their first Extraneal exchange, and 8 patients never exposed to Extraneal. In the first group of patients, glycemia was also measured with another analyzer (Glucocard; Menarini Diagnostics, Firenze, Italy) using a different enzymatic reaction (glucose oxidase). In a separate study, whole blood of a normal subject was spiked with concentrated solutions of glucose and icodextrin and some of its metabolites (maltose, maltotriose, maltopentaose). Once again, comparative measurements of glycemia were performed with the Accutrend Sensor, with two other kits using a glucose dehydrogenase enzyme reaction, and with the hexokinase reference method., Results: In 6 CAPD patients treated with once-daily exchanges with Extraneal for a minimum of 7 consecutive days, we confirmed overestimation of glycemia by the Accutrend Sensor of 65 +/- 26 mg/dL compared to reference values (p < 0.01), and of 69 +/- 25 mg/dL (p < 0.001) compared to measurements obtained with the Glucocard monitor. In 6 other CAPD patients studied at the end of one single icodextrin exchange, overestimation of 61 +/- 11 mg/dL was already present (p < 0.001). On the other hand, in 8 CAPD patients never treated with icodextrin, there was no discrepancy between the Accutrend Sensor readings and reference values. The measurements in spiked blood confirmed that only the Accutrend Sensor overestimates glycemia in the presence of maltose and glucose polymers. The overestimation decreased as the molecular size of the saccharides added to blood increased. There was no overestimation when other kits using a dehydrogenase enzyme were tested., Conclusion: The overestimation observed is probably related to the presence of oligosaccharides (mainly maltose), derivatives of glucose polymers present in Extraneal and absorbed via the peritoneal route, in the blood of patients treated with icodextrin. The glucose dehydrogenase characterizing the Accutrend Sensor, an enzyme of the pyrroloquinolinequinone class, very likely reacts with the free reducing group of the glucose molecule located at the end of each saccharide chain. This would not be the case for the Glucocard monitor using glucose oxidase, for other kits using glucose dehydrogenase, and for the reference method based on hexokinase. The Accutrend Sensor type of analyzers are therefore not suitable for regular monitoring of glycemia in diabetic PD patients treated with icodextrin.

Mycophenolate Mofetil (MMF) is a new immunosuppressive agent that selectively inhibits the proliferation of T and B lymphocytes. The use of MMF in renal transplantation significantly reduced the incidence of acute rejection episodes in the first year after transplantation. The main toxicities of MMF are the occurrence of diarrhea and leucopenia. This potent immunosuppressive agent is devoid of the nephrotoxicity of cyclosporin and of the multiple adverse effects of corticosteroids. Clinical trials are currently in progress to assess whether the use of MMF will allow the discontinuation of cyclosporine or corticosteroid therapy without leading to an increased risk of rejection. If results were positive, MMF would represent a significant advance in the field of renal transplantation.

Nonenzymatic and glutathione S-transferase (GST) catalyzed glutathione (GSH) conjugation has been postulated as a mechanism by which alkylating cytostatic drugs can be inactivated intracellularly. In this study, we describe studies on the glutathione-dependent biotransformation of thiotepa (tris(1-aziridinyl)phosphine sulfide), a trifunctional alkylating agent. 31P NMR studies showed that thiotepa is stable in 0.07 M phosphate buffer, pH 7.4 (t1/2 = 3300 min). In the presence of glutathione, the rate of disappearance of thiotepa increased greatly (t1/2 = 282 min). Both monoglutathionyl thiotepa and diglutathionyl thiotepa conjugates were identified by 31P NMR and mass spectrometry. Addition of GST A1-1 (alpha) to an incubation of thiotepa and GSH further increased the rate of disappearance of thiotepa (t1/2 = 100 min) and increased the rate of formation of monoglutathionyl thiotepa. The rate of formation of diglutathionyl thiotepa was not altered, suggesting that the formation of diglutathionyl thiotepa is not catalyzed by GST A1-1. The role of purified human GST on the formation of monoglutathionyl thiotepa was further studied by HPLC. In incubations with 0.2 mM thiotepa, 1 mM GSH, and 40 microM GST, both GST A1-1 and P1-1 enhanced the formation of the monoglutathionyl conjugate 30-35-fold above the nonenzymatic formation, while GST A2-2 and M1a-1a did not catalyze the rate of formation of this conjugate. Kms for the GST A1-1 (alpha) and P1-1 (pi) catalyzed formation of monoglutathionyl thiotepa were in the 5-7 mM range. Since the pH in tumors might be lower than in normal cells, the pH dependency of the GST P1-1 catalyzed formation of monoglutathionyl thiotepa was also studied. At all pHs tested (range, 5.5-8.5), a marked catalytic effect of both GST P1-1 and A1-1 on the formation of monoglutathionyl conjugates was noted. The role of GST on the formation of monoglutathionyl conjugates of tepa (tris(1-aziridinyl)phosphine oxide), the major metabolite formed from thiotepa, was also studied. Both GST A1-1 and P1-1 could enhance the formation of the glutathione conjugate 37-46-fold above the spontaneous levels, while GST M1a-1a and A2-2 again did not increase the rate of formation of this conjugate. The results of these studies show that the aziridine moieties in thiotepa/tepa are substrates for both GST A1-1 and P1-1. Thus, GST catalyzed glutathione conjugation of thiotepa might be an important factor in the development of drug resistance towards thiotepa.