Intra-cellular immunosuppressive drugs monitoring: A step forward towards better therapeutic efficacy after organ transplantation?

Immunosuppressive drugs (IS) used in solid organ transplantation are critical dose drugs with high intra- and inter-subject variability. Therefore, IS therapeutic drug monitoring (TDM), mainly as trough levels analysis, is a major support to patient management, mandatory to optimize clinical outcome. Even though transplant patients undoubtedly benefited by this pre-dose (C0) monitoring, the relationship between these C0 concentrations and the incidence of graft rejections remains hardly predictable. Identification and validation of additional biomarkers of efficacy are therefore very much needed. As the main IS effects are mediated through the inhibition of lymphocyte proliferation pathways, direct drug quantification within this target compartment would appear meaningful, providing hopefully more consistent information on drug efficacy. Due to the analytical performances improvement, these intracellular concentrations became accessible for comprehensive studies regarding clinical benefit of intracellular IS TDM after solid organ transplantation. Over the last ten years, number of studies investigated the potential relationship between IS blood and intracellular pharmacokinetics, genetic variability, and clinical efficacy after solid organ transplantation. A recent literature review suggests that calcineurin inhibitors (tacrolimus and cyclosporine) intracellular concentrations appear more closely related to drug efficacy than blood levels. This closer association has however not been described for the m-TOR inhibitors (sirolimus, everolimus) and the antimetabolite (mycophenolic acid). Additional larger and multicenter clinical trials are needed to confirm these observations.

Cyclosporine A disposition, hepatic and renal tolerance in Wistar rat.

Cyclosporine A, a potent calcineurin inhibitor, has been widely used in organ transplantation and in the treatment of autoimmune diseases. It has, however, been shown to induce serious renal and hepatic side effects. The drug is also used in preclinical studies, but with little published information on the optimal dose and route of administration in rodents. Objectives of this study were to identify efficient and safe doses of cyclosporine A in rodent and to assess its effects on hepatic and renal functions. For this purpose, we tested the effects of different doses and administration routes of cyclosporine A (5, 2.5 and 1 mg/kg) administered during 28 days intraperitoneally, or by gastric feeding on Wistar rats. Our data indicate that rats injected intraperitoneally with 5 mg/kg/2d (every two days) exhibited trough cyclosporine A levels within known therapeutic range in human, but were subject to blood cyclosporine A accumulation, whereas the 5 mg/kg/d gavage resulted in only a small cyclosporine A accumulation over time. In both cases this accumulation was not deleterious to renal and hepatic functions, as shown by transaminase, urea, creatinine and bilirubin measurements.

Population pharmacokinetic analysis of tacrolimus in the first year after pediatric liver transplantation.

PURPOSES: Tacrolimus (TAC) is the most widely used immunosuppressant for the prevention of acute rejection after solid organ transplantation. Its pharmacokinetics (PK) show considerable variability, making TAC a good candidate for therapeutic drug monitoring (TDM). The principal aim of the study was to describe the PK of TAC in pediatric patients during the first year after transplantation. METHODS: Routine TDM trough levels of TAC were obtained from 42 pediatric liver allograft recipients during the first year after transplantation. A population PK model was developed using nonlinear mixed-effects modeling to describe TAC PK during this period and to explain the observed variability by means of patients' demographics, biochemical test results and physiological characteristics. RESULTS: The PK of TAC were best described by a two-compartment model with first-order elimination. Apparent volumes of the central compartment, intercomparmental clearance and maximum blood clearance estimates were 253 L, 115 L/day and 314 L/day, respectively. The absorption first-order rate and volume of peripheral compartment were fixed to 4.5 h(-1) and 100 L, respectively. While hematocrit levels, time after transplantation and bodyweight influenced TAC clearance, bodyweight was the only covariate retained on volume of distribution. CONCLUSIONS: We developed a TAC population PK model in pediatrics covering the first year after liver transplantation that may serve as a tool for TAC dose individualization as part of TDM.

Inhaled phosphodiesterase type 5 inhibitors restore chloride transport in cystic fibrosis mice.

Sildenafil and vardenafil, two selective inhibitors of phosphodiesterase type 5 (PDE5) are able, when applied by intraperitoneal injection, to activate chloride transport in cystic fibrosis (CF) mice homozygous for the F508del mutation. Oral treatment with the drugs may be associated with adverse haemodynamic effects. We hypothesised that inhaled PDE5 inhibitors are able to restore ion transport in F508del CF airway epithelium. We developed a restraint-free mouse chamber for inhalation studies. PDE5 inhibitors were nebulised for 15 min at concentrations adjusted from recommended therapeutic oral doses for male erectile dysfunction. We measured in vivo nasal transepithelial potential difference 1 h after a single inhalation of sildenafil, vardenafil or tadalafil in F508del CF and normal homozygous mice. After nebulisation with the drugs in F508del mice, chloride transport, evaluated by perfusing the nasal mucosa with chloride-free buffer containing amiloride followed by forskolin, was normalised; the forskolin response was increased, with the largest values being observed with tadalafil and intermediate values with vardenafil. No detectable effect was observed on sodium conductance. Our results confirm the role of PDE5 inhibitors in restoring chloride transport function of F508del CF transmembrane conductance regulator protein and highlight the potential of inhaled sildenafil, vardenafil and tadalafil as a therapy for CF.

Cystatin C in cardiac surgery.

Cystatin C has recently been proposed as an alternative marker of glomerular filtration rate. The study compares cystatin C and creatinine concentrations during cardiopulmonary bypass and the first 72 hours postoperatively in patients undergoing coronary artery bypass graft. Forty-nine patients with normal preoperative renal and cardiac function were scheduled for coronary artery bypass graft. Blood was sampled for creatinine and cystatin C measurements at 7 time points till 72 hours postoperatively. Glomerular filtration rate was estimated from calculated clearance using the Cockroft and Gault formula for creatinine and Larsson equation for cystatin C. The baseline values of both markers were within the normal range. Their concentrations were comparable during the whole study period. This was also the case for the calculated creatinine and cystatin C clearance. In patients with normal preoperative renal function undergoing coronary artery bypass graft, measured creatinine concentration remains a cheap and easy way of estimating renal function.

Impact of Acute Infection Requiring Hospitalization on Tacrolimus Blood Levels in Kidney Transplant Recipients.

BACKGROUND: Tacrolimus is metabolized by members of the cytochrome p450 3A subfamily, and its bioavailability depends also on P-glycoprotein. We have observed that some patients admitted for infection presented with increased tacrolimus trough levels (TLs). The aim of the study was to assess the impact of infection on tacrolimus TLs and to determine the factors involved in TL fluctuations. METHODS: This retrospective cohort study included patients transplanted with a kidney between 2009 and 2011 who were hospitalized for an acute infection. Tacrolimus TLs and dosages were recorded before hospitalization, at admission, and 1 month after discharge. Increased levels of tacolimus were defined as TL 25% higher on admission than those recorded at the last visit before hospitalization. RESULTS: Seventy-seven patients were hospitalized 138 times for infection. More than two thirds of first hospitalizations occurred during the first post-transplant year. Causes of hospitalization were urinary (33%), cytomegalovirus (27%), digestive (15%), and pulmonary (12%) infections. Thirty-five percent of kidney transplant recipients had increased tacrolimus TLs (27/77 patients) in 24% of the hospitalizations (34/138). In 34 hospitalizations occurring in 27 patients, TL at admission was ≥25% compared with the last visit before admission. Comparing these 34 hospitalizations with the other 104, no significant differences were noted, except for a greater fraction of digestive infections in the group with elevated tacrolimus TLs, independent of diarrhea occurrence. CONCLUSIONS: Up to 35% of kidney transplant recipients admitted for acute infection present with high tacrolimus TLs, requiring a dose reduction. How acute infection precisely affects metabolism and bioavailability of tacrolimus remains to be investigated.

Multi-center evaluation of analytical performance of the microparticle enzyme immunoassay for sirolimus.

OBJECTIVES: This study evaluated the analytical characteristics of the new Abbott microparticle enzyme immunoassay (MEIA) for sirolimus. DESIGN AND METHODS: The protocol consisted of nine sections: evaluation of antibody specificity, linearity, detection limit, quantification limit, endogenous interferents, exogenous interferents, precision, proficiency testing panel, and method comparison. RESULTS: The mean analytical detection limit was 0.68 microg/L. The sirolimus concentration corresponding to a total CV of 20% was 1.5 microg/L. Linearity of response was demonstrated across the dynamic range of the assay. Total precision (CVs) at QC control levels from 5 to 22 microg/L ranged from 5.7 to 12.6%. Assay standardization was found to be in good agreement with LC/MS/MS as compared with target values for spiked sirolimus proficiency samples from an international sirolimus proficiency testing program. Good correlations (R values) of the immunoassay were observed in comparisons to LC/MS/MS. R values tended to be lower in comparisons with LC/UV methods. Across both LC-based methods and all study sites, there was approximately 25% overall positive slope bias due to cross reactivity of the MEIA antibody to metabolites of sirolimus. The assay cross-reactivity to metabolites of sirolimus parent drug ranged from 6 to 63%. Assay interferences were minimal with the exception of hematocrit, which presented a negative relationship to measured sirolimus concentration. CONCLUSIONS: The MEIA demonstrated acceptable analytical characteristics for use for routine monitoring of sirolimus immunosuppressive therapy, and is a viable alternative to HPLC-based methods for sirolimus monitoring.

Comparison of lung deposition of amikacin by intrapulmonary percussive ventilation and jet nebulization by urinary monitoring.

The intrapulmonary percussive ventilation (IPV), frequently coupled with a nebulizer, is increasingly used as a physiotherapy technique; however, its physiologic and clinical values have been poorly studied. The aim of this study was to compare lung deposition of amikacin by the nebulizer of the IPV device (Percussionaire; Percussionaire Corporation; Sandpoint, ID) and that of standard jet nebulization (SST; SideStream; Medic-Aid; West Sussex, UK). Amikacin was nebulized with both devices in a group of five healthy subjects during spontaneous breathing. The deposition of amikacin was measured by urinary monitoring. Drug output of both devices was measured. Respiratory frequency (RF) was significantly lower when comparing the IPV device with SST (8.2 +/- 1.6 breaths/min vs. 12.6 +/- 2.5 breaths/min, p < 0.05). The total daily amount of amikacin excreted in the urine was significantly lower with IPV than with SST (0.8% initial dose vs. 5.6% initial dose, p < 0.001). Elimination halflife was identical with both devices. Drug output was lower with IPV than with SST. The amount of amikacin delivered to the lung is sixfold lower with IPV than with SST, although a lower respiratory frequency was adopted by the subjects with the IPV. Therefore, the IPV seems unfavorable for the nebulization of antibiotics.

Successful protocol of anaesthesia for measuring transepithelial nasal potential difference in spontaneously breathing mice.

Numerous difficulties arise during in vivo measurements of transepithelial nasal potential difference (PD) in mice, such as inadequate duration and depth of anaesthesia, bronchoaspiration of solutions perfused in the nose, and respiratory and/or cardiovascular depression. Anaesthesia was induced in adult C57 mice with intraperitoneal injection of a combination of fentanyl, droperidol and medetomidine, each of these at either a small dose (0.20, 10 and 0.33 mg/kg, respectively) or at a large dose (0.40, 20 and 0.40 mg/kg, respectively), combined with a fixed dose of 0.375 microg clonidine. In order to establish a pharmacokinetic-pharmacodynamic relationship, blood concentrations of the first three drugs were measured in 24 animals by liquid-chromatography tandem mass spectrometry. At the end of the experiment, naloxone, a competitive morphinic antagonist, and atipamezole, an alpha-2 adrenergic antagonist, were administered. Bronchoaspiration was prevented by tilting the animal head downwards and by absorbing the excess fluid from the opposite nostril and from the oral cavity. Optimal assessment of anaesthesia associated with regular respiration, loss of blink, pupillary and pedal withdrawal reflexes was obtained with doses of fentanyl, droperidol and medetomidine corresponding to 0.20, 20 and 0.40 mg/kg, respectively. Blood concentrations of fentanyl around 17 ng/mL induced loss of respiratory efforts and were followed by death during the experiment. Integrity of ion transport was demonstrated under continuous perfusion by successive depolarization after amiloride and repolarization after chloride-free solution. The combination investigated in this study lead to adequate surgical anaesthesia (stage III, plane 2) for prolonged nasal PD measurements in spontaneously breathing mice.

Key pharmacokinetic parameters of isepamicin in febrile neutropenic cancer patients and in women with acute pelvic inflammatory disease.

The pharmacokinetics (PK) of isepamicin were studied in 8 febrile neutropenic patients with hematologic malignancy and in 20 young women with acute pelvic inflammatory disease (PID). Isepamicin was given as a slow intravenous infusion over 30 min at a dose of 15 mg/kg once daily (OD). Serum levels of isepamicin were determined by fluorescence polarization immunoassay, and PK analyses were obtained based on a one-compartment open model after 24 hours (steady state) and after 7 days. On day 1, the volume of distribution (Vd) of isepamicin, for both populations, appeared about 30% higher than classically reported in healthy individuals: 0.31 and 0.36 L/kg for neutropenic and PID patients respectively. However on day 7, Vd displayed significant reduction (0.28 and 0.27 L/kg, respectively for neutropenic and PID patients). A reduction of isepamicin clearance was also observed between day 1 and day 7 (137 vs 120 mL/min and 130 vs 101 mL/min for neutropenic and PID populations, respectively). Such changes are consistent with a significant increase in the Cmax concentrations (45 vs 50 mg/L, and 38 vs 49 mg/L) and in the AUC (136 vs 158 and 137 vs 162 mg/L.h) observed after a week of treatment in neutropenic and PID patients, respectively. In conclusion, taking into account the importance of reaching early active concentrations, we recommend the use of higher loading dose of isepamicin (>15 mg/kg) in neutropenic cancer patients and in women with PID, particularly in case of a combination with a possibly ineffective antibacterial agent, in case of infection with bacteria at upper limit of susceptibility, in the presence of high infectious inoculum or in the presence of sequestered sites of infection.

Evaluation of a new immunoassay to measure sirolimus blood concentrations compared to a tandem mass-spectrometric chromatographic analysis.

A new immunoassay of sirolimus based on the microparticle enzyme immunoassay (MEIA) principle has been developed with collaboration of Abbott Diagnostics. Laboratories and Axis-Shield. Our laboratory evaluated this new assay on 153 whole blood samples (EDTA) drawn from a population of renal (n = 141) and hepatic (n = 12) transplant patients. Each blood sample was analyzed simultaneously by MEIA (Y) and by a reference method (X) used routinely in our laboratory, namely, liquid chromatography tandem mass spectrometry (LC-MS/MS). The statistical analysis of Passing-Bablok produced the following results: Spearman r value = 0.95, slope = 1.15 and intercept with the Y axis = +0.2 ng/mL. The observed global overestimation of 15% compared to the reference method could be explained by the cross-reactivity of sirolimus metabolites with the antibody. A complementary analysis taking into account the transplanted organ (kidney versus hepatic) did not show any significant difference between the populations, most likely owing to the low number of hepatic transplantation samples. The analytical performance of the MEIA method showed CV < or =10% and a limit of quantification of 1.5 ng/mL, which were acceptable for routine clinical monitoring. In conclusion, the MEIA method has shown robust, stable, reproducible, features with an excellent correlation with the reference LC-MS/MS method.

Formate kinetics in methanol poisoning.

OBJECTIVE: The objective is to describe the kinetics of formate, the main toxic metabolite of methanol, in a series of consecutive patients treated in the same intensive care unit for severe methanol poisoning. METHODS: The charts of the patients admitted between 1987 and 2001 were reviewed. Inclusion criteria were: a history of deliberate methanol ingestion, with a blood methanol concentration greater than 20 mg/dL (6.2 mmol/L) or a high anion gap metabolic acidosis. Indications for hemodialysis were: blood methanol concentration >50 mg/dL (15.8 mmol/L), metabolic acidosis (bicarbonate <15 mmol/L, arterial pH <7.30), visual toxicity. Antidotal therapy included ethanol administration in 22 cases, and fomepizole in three cases. Serial blood measurements were obtained for pH, bicarbonate, methanol and formate. Endogenous and hemodialysis elimination half-lives were calculated as t1/2 =0.693/Ke. Fick principle was applied for hemodialysis clearance calculation. RESULTS: The records of 25 methanol poisoned patients were analysed. Among them, 18 patients had sufficient data to allow accurate determinations of formate kinetics. Formate half-life elimination during hemodialysis was 1.80+/-0.78 h, which was statistically different from the values observed before or in the absence of dialysis (6.04+/-3.26 h, P =0.004). The mean hemodialysis formate clearance rate calculated in eight cases was 176+/-43 mL/min. A rebound in plasma formate concentration was observed in three patients after the discontinuation of hemodialysis. CONCLUSIONS: In accordance with previous isolated case reports and in contrast with a recent case series, our data document that hemodiaysis is effective in reducing formate elimination half-life. The impact on clinical outcome is still debatable.

Hyperhomocysteinemia in type 2 diabetes: relationship to macroangiopathy, nephropathy, and insulin resistance.

OBJECTIVE: The aim of this study was to determine the distribution of plasma total homocysteine (tHcy) concentrations in type 2 diabetic patients and to assess whether high tHcy values were related to chronic complications (particularly macroangiopathy and nephropathy) and/or the degree of insulin resistance. RESEARCH DESIGN AND METHODS: Fasting tHcy levels were measured in 122 type 2 diabetic patients in whom the presence of chronic complications (e.g., macroangiopathy, microalbuminuria, macroproteinuria, decreased creatinine clearance, hypertension, retinopathy, and neuropathy) was recorded alongside an assessment of insulin resistance by the homeostasis model assessment (HOMA). RESULTS: We found that 31% of the cohort (group 1) had raised tHcy (mean +/- 1 SD) values (20.8 +/- 5.1 micromol/l), whereas 69% (group 2) had normal values (10.2 +/- 2.0 micromol/l). The prevalence of macroangiopathy was higher in group 1 than in group 2 subjects (70 vs. 42%, P < 0.01); the prevalence of coronary artery disease was particularly higher in group 1 (46 vs. 21%, P < 0.02). The prevalence of impaired renal function, evidenced by decreased creatinine clearance, was higher in group 1 (32 vs. 10%, P < 0.005). Other clinical and biological characteristics of both groups were comparable, although group 1 had lower levels of folic acid than group 2 (5.2 +/- 2.9 vs. 7.0 +/- 3.4 ng/ml, P < 0.01). No differences were found for microalbuminuria (33 vs. 31%), retinopathy (45 vs. 42%), or neuropathy (70 vs. 59%) between groups 1 and 2, respectively The degree of insulin resistance was similar in groups 1 and 2 (46 +/- 21 and 42 +/- 20% of HOMA-insulin sensitivity) as was the assessment of beta-cell function (63 +/- 28 and 65 +/- 46%, respectively). No differences in tHcy levels were found between subjects receiving metformin and those not receiving metformin. In contrast, the plasma tHcy level was higher in diabetic patients treated with fibrates (P = 0.0016). CONCLUSIONS: Elevated plasma tHcy levels in type 2 diabetes is associated with a higher prevalence of macroangiopathy and nephropathy when assessed from creatinine clearance indexes and is not associated with different degrees of insulin resistance.

How appropriate is therapeutic drug monitoring for lithium? Data from the Belgian external quality assessment scheme.

BACKGROUND: Lithium remains a mainstay in the management of mood disorders. As with many psychotropic drugs, lithium treatment requires continuous observation for adverse effects and strict monitoring of serum concentrations. The present study aimed to assess the appropriateness of lithium assays used by Belgian laboratories, and to evaluate acceptability of their clinical interpretations. METHODS: Nine in-house serum samples spiked with predetermined concentrations of lithium were distributed to 114 participants in the Belgian external quality assessment scheme. Laboratories were requested to report the assay technique, lithium measurements and interpretations with regard to measured concentrations. Inter/intramethod imprecision and bias were reported and acceptability of clinical interpretations was assessed. The intramethod variability was evaluated by selecting methods used by 6 laboratories or more. Flame photometry (IL 943) was considered as the reference method. RESULTS: Laboratories returned assay results using colorimetry (69.3%), ion selective electrode (15.8%), flame photometry (8.8%), atomic absorption spectroscopy (5.2%) or mass spectrometry (0.9%). Lithium concentrations were systematically higher when measured with the Vitros assay (median bias: 4.0%), and were associated with consecutive biased interpretations. In contrast, the Thermo Scientific Infinity assay showed a significant negative bias (median bias: 9.4%). 36.0% of laboratories reported numerical values below their manufacturer cut-off for the blank sample; 16.6% of these laboratories detected residual lithium concentrations. CONCLUSIONS: The present study revealed assay-related differences in lithium measurements and their interpretations. Overall, there appeared to be a need to continue EQA of therapeutic drug monitoring for lithium in Belgium.

The unreliability of the lidocaine/monoethylglycinexylidide test for assessment of liver donors.

The serum monoethylglycinexylidide (MEGX) level 15 min (t15) after i.v. administration of lidocaine (1 mg/kg) in liver donors was retrospectively correlated with graft outcome and early hepatic function. Among the 35 orthotopic liver transplants studied, 4 recipients had to be retransplanted within 10 days post-OLT because of early graft nonfunction or dysfunction, and 3 recipients died, with a median (range) donor MEGX t15 (ng/ml) of 100 (86-119) and 169 (146-182), respectively. The remaining 28 OLT patients living with functioning grafts had a donor MEGX of 87 (18-245). No significant correlations could be found between donor MEGX t15 and recipient mean and peak glutamic-oxaloacetic and -pyruvic transaminases, total serum bilirubin, or mean and minimum prothrombin time values studied from day 1 to day 5 post-OLT. Moreover, categorization of donors using the MEGX t15 cut-off point of 80 ng/ml could not predict liver graft quality, as previously suggested. In summary, MEGX t15 in liver donors correlated neither with graft outcome nor with early functional parameters. Accordingly, the MEGX test should not be used as an isolated discriminatory evaluation for organ utilization.

Conversion from cyclosporine to FK506 for salvage of immunocompromised pediatric liver allografts. Efficacy, toxicity, and dose regimen in 23 children.

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.

Transjugular intrahepatic portosystemic shunt after adult liver transplantation: experience in eight patients.

BACKGROUND: Transjugular intrahepatic portosystemic shunting (TIPS) has become an effective treatment for the complications of portal hypertension. We assessed the feasibility and outcome of TIPS in liver transplant recipients. METHODS: During the period from December 1992 to January 1998, eight adults presenting recurrent hepatitis C virus (five patients) and hepatitis B virus (one patient) infection, veno-occlusive disease (one patient), and secondary biliary cirrhosis (one patient) had TIPS because of refractory ascites (five patients), bleeding esophageal varices (one patient), refractory hepatic hydrothorax (one patient), retransplantation (two patients), and redo-biliary surgery (one patient). RESULTS: In two patients, the procedure was difficult due to cavo-caval implantation. Ascites, hydrothorax, and variceal bleeding were controlled in all patients. Moderate to severe encephalopathy developed in four patients; two patients had worsening of their existing encephalopathy. Three of five patients treated with cyclosporine needed a drastic dose reduction due to the development of severe side effects. No long-term survivor developed shunt stenosis or occlusion. Two patients did moderately well at 6 and 14 months, respectively; the former died due to chronic rejection while waiting for a retransplantation. Three did well at 14, 36, and 28 months, respectively; the latter patient died of liver failure 32 months after TIPS. One jaundiced patient died after 1.5 months due to necrotic pancreatitis. Two patients died after 4 and 8.5 months, respectively, due to liver failure; the latter was doing well until 7 months after TIPS. CONCLUSIONS: TIPS is feasible in transplant recipients in cases of decompensated allograft cirrhosis, of allograft veno-occlusive disease or when retransplantation or redo-biliary surgery are scheduled in the presence of portal hypertension. At transplantation, the surgeon should keep in mind the eventuality of a later TIPS procedure. Close immunosuppression monitoring is warranted because modified metabolization of cyclosporine (and probably tacrolimus) may cause serious side effects.

Early hepatocyte, endothelial, and bile duct cell injury after pediatric liver transplantation from cadaveric or living-related donors.

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. METHODS: The aim of this study was to analyze early hepatocyte, endothelial, and bile duct cell injury following pediatric OLT using LR (n=15) or uncomplicated Cad reduced-size (n=10) grafts. Median (range) total ischemic times were 190 min (105-261) versus 760 min (418-948) in LR and Cad groups, respectively (P<0.001). RESULTS: The post-OLT cytolytic profile, assessed daily during the first 7 days using both plasma glutamate-pyruvate transaminase and serum alpha-glutathione S-transferase, showed significantly higher levels of both parameters for the 10 uncomplicated Cad cases when compared with the 15 LR grafts (P<0.001). The evaluation of hepatic endothelial cell function during the first week after OLT, using serum hyaluronic acid levels, suggested lower endothelial injury in the LR grafts, when compared with the Cad grafts (P=0.059). Bile duct cell injury, as assessed using plasma gamma-glutamyl transferase levels, was similar in both groups, with a progressive increase at the end of the first week after OLT, which was correlated with a similar incidence of early acute rejection in both groups (80% in the LR group vs. 62% in the Cad group, NS). CONCLUSION: (1) The hepatocellular and endothelial cell damage was reduced after OLT with LR grafts, which may be related to shorter ischemic time when compared with Cad grafts; (2) the putative immunologic advantage for LR grafts was not confirmed in terms of incidence of acute rejection.

Microemulsion formulation of cyclosporine in pediatric liver transplantation.

The oral bioavailability of Sandimmun can be impaired by cholestasis, external biliary diversion, and diarrhea. We report two cases of pediatric liver transplant recipients who experienced chronic rejection and diarrhea secondary to proximal bowel resection. These conditions resulted in poor oral absorption of Sandimmun; the children were converted to the new oral microemulsion formulation Neoral, which significantly improved oral absorption, allowing intravenous cyclosporine weaning and patient discharge. Comparative pharmacokinetic studies were performed in both cases, and the relative Neoral/Sandimmun bioavailabilities were 32.9 and 5.4, respectively. Accordingly, Neoral may constitute to good alternative to ensure the effectiveness of oral cyclosporine administration, particularly in liver-transplanted children with severe cholestasis or shortened small bowel.

Early signs and risk factors for the increased incidence of Epstein-Barr virus-related posttransplant lymphoproliferative diseases in pediatric liver transplant recipients treated with tacrolimus.

BACKGROUND: Posttransplant lymphoproliferative disease (PTLD) is a life-threatening condition the incidence of which in pediatric solid organ transplantation may be related to the immunosuppressive load. It has been suggested that tacrolimus, a new and potent immunosuppressor, causes an increased incidence of this syndrome. METHODS: The incidence, early signs, and risk factors for lymphoproliferative disease were reviewed in a cohort of 89 pediatric liver transplant recipients treated with tacrolimus. RESULTS: Eighteen patients (20%) developed a PTLD-16 concomitant to a primary Epstein-Barr virus (EBV) infection and 2 with previous immunity against EBV. Three additional patients had preliminary signs of PTLD concomitant to primary EBV infection, but did not develop individualized lymphoid masses. Six patients died (6.7% of all tacrolimus-treated patients). Mean tacrolimus blood level during the 3 months preceding EBV infection reached 11.8+/-1.8 ng/ml in PTLD patients versus 9.4+/-3.4 ng/ml in non-PTLD patients (0.05