Marion Aw

Human hepatocyte isolation and relationship of cell viability to early graft function.

Hepatocyte transplantation is emerging as an additional modality of treatment for patients with acute liver failure or liver-based metabolic disorders. The procedure requires isolation of high-quality hepatocytes from unused donor livers. Hepatocytes were isolated from 20 donor livers (11 right lobes, 3 left lateral segments, 6 whole livers) using a collagenase perfusion technique. Cell viability (median 56%, range 13–95%) and yield (median 1.4 × 109 cells, range 2.0 × 106–1.8 × 1010 cells) varied according to the tissue available. Fatty livers rejected for transplantation gave lower cell viability (median 45%, range 25–59%). There was a significant correlation between age of donor (median 21 years, range 7–66 years) and viability of isolated hepatocytes in vitro (r = −0.683, p = 0.001). The 13 segments of livers were from reduced/split grafts used for clinical transplantation in 9 children and 4 adults. There was no significant correlation between in vitro cell viability and clinical parameters including intensive care stay, serum aspartate aminotransferase, and international normalized ratio (in the first 7 days), and allograft rejection or other early posttransplant complications, in patients transplanted with the corresponding tissue.

Mycophenolate mofetil as rescue treatment for autoimmune liver disease in children: A 5-year follow-up

BACKGROUND/AIM The aim of this study was to evaluate the outcome of mycophenolate mofetil (MMF) therapy in children with autoimmune liver disease who are resistant to or intolerant of standard immunosuppression. METHODS INCLUSION CRITERIA (a) failure to achieve/maintain remission with prednisolone/azathioprine therapy or (b) significant treatment side-effects. Initial MMF dose was 20mg/kg/day, gradually increased to a maximum of 40 mg/kg/day. Azathioprine was stopped when MMF was commenced. RESULTS Twenty-six children (17 female) were recruited. Median (range) age at diagnosis was 9.9 (1.2-14.4) years. Sixteen had Type 1 autoimmune hepatitis (AIH), two Type 2 AIH, and eight had autoimmune sclerosing cholangitis (ASC). Median (range) time from diagnosis to addition of MMF was 14.9 (0.2-108.6) months. Eighteen children responded to MMF, aspartate aminotransferase (AST) normalising in 14. At median (range) follow-up of 61.5 (19.5-96.3) months, AST remained normal in 12. All 18 children were well, but two had clinical signs of portal hypertension. Eight (6 ASC) did not respond: AST remained elevated in seven, one was listed for transplant for decompensated liver disease and one had clinical signs of portal hypertension. MMF was well tolerated. Leukopenia (n=7) was the most common side-effect. CONCLUSIONS MMF is an effective rescue therapy for children with AIH, but not for those with ASC.

Use of hypoallergenic formula in the prevention of atopic disease among Asian children.

Objective: To determine the effect of a partially hydrolysed formula on genetically predisposed children, with respect to the development of atopic clinical manifestations and in vitro testing of serum IgE levels (total and milk‐specific).

Mycophenolic acid and mycophenolic acid glucuronide pharmacokinetics in pediatric liver transplant recipients: Effect of cyclosporine and tacrolimus comedication

Determinants of the wide interindividual variability of the pharmacokinetics of mycophenolic acid (MPA) in 21 stable pediatric liver transplant recipients were investigated in relation to the kinetics of the drugs major phenolic glucuronide metabolite (MPAG), cyclosporin (CsA), or tacrolimus (Tac) co-medication and liver and renal function. Trough concentrations (C0) most reliably predicted the area under the curve (AUC) of 0–7 hours MPA plasma concentrations (r2 = 0.650). Co-medication with CsA demanded higher MPA mofetil (MMF) doses to achieve equivalent trough levels than Tac (362 vs. 178 mg per mg/L, P = 0.004). Median MPA C0 (range) was significantly lower during CsA co-therapy when corrected for MMF dose (2.8 vs. 5.6 mg MPA/L for Tac, P = 0.006). The AUC of MPAG was correspondingly higher during CsA co-medication (229 vs. 94 mg/L/h for Tac, P = 0.012) with the MPA-to-MPAG ratio at C0 correspondingly lower (0.10 vs. 0.14, respectively, P = 0.04). This suggested contrasting effects of CsA and Tac on MPA glucuronidation or its excretion and enterohepatic recirculation. MPAG AUC was correlated to body weight and creatinine clearance. Children with elevated aspartate transaminase (AST; but with no evidence of rejection on liver biopsy, n = 7) had significantly lower MPA trough levels compared with those in whom AST was normal (0. 77 vs. 1.76 mg/L, P = 0.05), but there was no difference in the MMF dose per body weight. Examination of the MPA profiles in these subjects showed significantly lower MPA concentrations from 120 minutes after dose until the end of the 7-hour profile and suggest an accelerated clearance or decreased enterohepatic recirculation.

Effect of a Milk Formula Containing Probiotics on the Fecal Microbiota of Asian Infants at Risk of Atopic Diseases

The fecal microbiota of 37 infants with (n = 20) or without (n = 17) probiotic administration was evaluated on D 3, and at 1, 3, and 12 mo by fluorescence in situ hybridization-flow cytometry (FISH-FC), PCR, and bacteriological culture methods. They represent consecutive subjects of an ongoing double-blind, placebo-controlled trial on a probiotic formula (LGG and Bifidobacterium longum) administered during the first 6 mo of life. Despite varying composition in each baby, there was a general bacterial colonization pattern in the first year. Bifidobacteria increased markedly (p = 0.0003) with a parallel decrease in Enterobacteriaceae (p < 0.001) and Bacteroides–Prevotella (p = 0.005) populations. Eubacterium rectale–Clostridium coccoides (p < 0.001) and Atopobium (p = 0.039) groups also gradually increased. This overall pattern was unaffected by probiotic administration (p > 0.05). B. longum (p = 0.005) and Lactobacillus rhamnosus (p < 0.001) were detected more frequently in probiotic group during supplementation, but no difference after supplementation had ceased (p > 0.05). Cultured lactic acid bacteria were also more numerous in the probiotic-administered babies during treatment period (log10 CFU/g 8.4 versus 7.4; p = 0.035). Our results indicate that supplemented strains could be detected but did not persist in the bowel once probiotic administration had ceased.

Effect of probiotic supplementation in the first 6 months of life on specific antibody responses to infant Hepatitis B vaccination.

Probiotics have been shown to enhance specific immune responses to vaccines. We aim to assess the effect of probiotic supplementation on specific IgG antibody responses to Hepatitis B (HepB) vaccination in infants. Compared to controls, probiotic supplementation improved HepB surface antibody responses in subjects receiving monovalent doses of HepB vaccine at 0, 1 month and a DTPa-HepB combination vaccine at 6 months [placebo (n=28): 187.97 (180.70-195.24), probiotic (n=29): 345.70 (339.41-351.99)mIU/ml] (p=0.069), but not those who received 3 monovalent doses [placebo (n=68): 302.34 (296.31-308.37), probiotic (n=77): 302.06 (296.31-307.81)mIU/ml] (p=0.996). Probiotics may enhance specific antibody responses in infants receiving certain Hepatitis B vaccine schedules.

Calcineurin-inhibitor related nephrotoxicity- reversibility in paediatric liver transplant recipients.

Aim. To study the efficacy of mycophenolate mofetil (MMF) as renal rescue in paediatric liver transplant recipients with calcineurin-inhibitor- (CI) related nephrotoxicity. Methods. Pediatric liver transplant recipients with stable graft function and a glomerular filtration rate (GFR) <80 ml/min/1.73 m2 were enrolled. MMF was introduced at 20 mg/kg/day and increased to 40 mg/kg/day after 1 week. CI dose was then reduced 6 weeks to achieve blood levels 25% of baseline. GFR was reassessed after 6 and 12 months. Results. Fourteen children with a median (range) interval from transplant of 57 (4-111) months were studied. Their median (range) GFR in ml/min/1.73 m2 increased from a baseline of 52 (31–71), to 69 (38–111) and 73 (35–98) at 6 and 12 months, respectively (P =0.00014). Side effects of MMF include leucopaenia in two and backache in one, two of whom discontinued MMF. Acute allograft rejection occurred in three children. All 14 are well with a median (range) follow-up of 24 (14–38) months from MMF introduction. Conclusion. MMF allows the recovery of renal function from CI related nephrotoxicity in more than 70% of paediatric liver transplant recipients with renal impairment.

Basiliximab (Simulect) for the treatment of steroid-resistant rejection in pediatric liver transpland recipients: a preliminary experience1

Background. The role of interleukin-2 receptor antibodies as rescue therapy in steroid-resistant rejection (SRR) has not been studied. We evaluated the safety and efficacy of an interleukin-2 receptor antibody, basiliximab (Simulect, Novartis, East Hanover, NJ), in treating SRR in pediatric liver transplant recipients. Methods. This was a prospective study of seven pediatric liver transplant recipients with biopsy-proven SRR who would have otherwise received OKT3 or antithymocyte globulin. The primary immunosuppression consisted of cyclosporine (Neoral, Novartis), azathioprine, and prednisolone in four patients and tacrolimus and prednisolone in three patients who had undergone retransplantation for chronic rejection (n=2) and hyperacute rejection (n=1). Four patients had received two cycles of high-dose steroids, and three patients had received a single cycle; all had been converted to tacrolimus, followed by the addition of mycophenolate mofetil. Results. The median time from transplant to SRR was 30 days (range, 8 days–23 months). Five children received two doses of basiliximab (10 mg, 3–7 days apart), and two children received a single dose. Aspartate aminotransferase levels normalized in three children 12, 21, and 30 days after basiliximab treatment. Aspartate aminotransferase levels decreased without normalizing in two children, but there was no further evidence of cellular rejection on repeat biopsies. All five children are rejection-free with a median follow-up of 22 months (range, 5–32 months). Biochemical abnormalities persisted in the remaining two children, and both developed chronic rejection. There were no immediate side effects associated with basiliximab. Two patients were treated empirically for possible cytomegalovirus infection 21 and 57 days after basiliximab treatment, with no evidence of cytomegalovirus disease. Conclusion. Five of seven pediatric liver transplant recipients with SRR experienced successful outcomes with basiliximab treatment without major side effects, indicating that it is a safe alternative to OKT3 and other antilymphocyte antibodies.

Population pharmacokinetics of tacrolimus in whole blood and plasma in asian liver transplant patients.

ObjectivesThe objectives of this study were to develop population pharmacokinetic models of tacrolimus in an Asian population with whole blood and plasma drug concentration data, to compare the variability of the pharmacokinetic parameters in these two matrices and to search for the main patient characteristics that explain the variability in pharmacokinetic parameters.Study designProspective pharmacokinetic assessment followed by model fitting.PatientsWhole blood samples from 31 liver transplant patients in a local hospital receiving oral tacrolimus as part of their immunosuppressive therapy were assessed. Plasma samples from 29 of the 31 patients were also evaluated. Concentrations of tacrolimus in whole blood and plasma were determined by an electrospray high-performance liquid chromatography with tandem mass spectrometry. Two hundred and thirteen whole blood and 157 plasma tacrolimus concentrations were used for building two nonlinear mixed-effects population models to describe the disposition of tacrolimus in whole blood and plasma, respectively. Covariates that were investigated included demographic characteristics, biological markers of liver and renal functions, corticosteroid dose and haematological parameter.ResultsA one-compartment model was used to describe the whole blood and plasma concentration-time data of tacrolimus after oral administration. For the whole blood population model, the population estimates of the first-order absorption rate constant (ka), apparent clearance based on whole blood concentration after oral administration (CLB/F) and apparent volume of distribution based on whole blood concentrations after oral administration (Vd,B/F) were 2.08h−1, 14.1L/h and 217L, respectively. The coefficient of variations (CVs) of interpatient variabilities in CLB/F and Vd,B/F were 65.7% and 63.8%, respectively. Bodyweight, liver and renal function influenced CLB/F, while height and haematocrit influenced Vd,B/F. The residual (unexplained) variability was 34.8%. For the plasma population model, the population estimates of the ka, apparent clearance based on plasma concentrations after oral administration (CLp/F) and apparent volume of distribution based on plasma concentrations after oral administration (Vd,p/F) were 5.21h−11, 537 L/h and 563L, respectively. The CVs of interpatient variabilities in CLp/F and Vd,p/F were 96.0% and 105.4%, respectively. Bodyweight was found to influence CLp/F, while the erythrocyte-to-plasma concentration ratio influenced Vd,p/F. The residual (unexplained) variability was 49.8% at the mean plasma concentration of 1.1 ng/mL.ConclusionsWhole blood and plasma population pharmacokinetic models of tacrolimus in Asian adult and paediatric liver transplant patients were developed using prospective data in a clinical setting. This has identified and quantified sources of interindividual variability in CLB/F, Vd,B/F, CLp/F and Vd,p/F of tacrolimus in Asian liver transplant patients. Information derived from the whole blood population model may subsequently be used by clinicians for dosage individualisation through Bayesian forecasting.

MARS®: a futile tool in centres without active liver transplant support

Background and aim: Studies on Molecular Adsorbent Recycling Systems (MARS®) showed inconclusive survival benefits.