Beth A. Carter

Stigmasterol, a soy lipid-derived phytosterol, is an antagonist of the bile acid nuclear receptor FXR.

Phytosterols, components of soy-derived lipids, are among the proposed exacerbants of parenteral nutrition–associated cholestasis (PNAC). We investigated whether phytosterols contribute to bile acid (BA)–induced hepatocyte damage by antagonizing a nuclear receptor (NR) critically involved in hepatoprotection from cholestasis, FXR (farnesoid X receptor, NR1H4). In HepG2 cells, stigmasterol acetate (StigAc), a water-soluble Stig derivative, suppressed ligand-activated expression of FXR target genes involved in adaptation to cholestasis (i.e. BSEP, FGF-19, OSTα/β). Furthermore, StigAc antagonized BA-activated, FXR target genes SHP and BSEP in FXR+/+, but not in FXR−/− mouse hepatocytes. Both Stig and StigAc inhibited BA-activated, FXR-dependent reporter gene expression in transfected HepG2 cells, whereas the most prevalent phytosterol in lipids, β-sitosterol, had no inhibitory effect. Finally, among six ligand-activated NR-ligand binding domains (LBDs) tested, antagonism by StigAc was specific to only two (FXR and PXR, pregnane X receptor, NR1I2). We demonstrate that Stig, a phytosterol prevalent in soy-derived PN lipid solutions, is a potent in vitro antagonist of the NR for bile acids FXR.

Natural History of Pediatric Intestinal Failure: Initial Report from the Pediatric Intestinal Failure Consortium

OBJECTIVE To characterize the natural history of intestinal failure (IF) among 14 pediatric centers during the intestinal transplantation era. STUDY DESIGN The Pediatric Intestinal Failure Consortium performed a retrospective analysis of clinical and outcome data for a multicenter cohort of infants with IF. Entry criteria included infants <12 months receiving parenteral nutrition (PN) for >60 continuous days. Enteral autonomy was defined as discontinuation of PN for >3 consecutive months. Values are presented as median (25th, 75th percentiles) or as number (%). RESULTS 272 infants with a gestational age of 34 weeks (30, 36) and birth weight of 2.1 kg (1.2, 2.7) were followed for 25.7 months (11.2, 40.9). Residual small bowel length in 144 patients was 41 cm (25.0, 65.5). Diagnoses were necrotizing enterocolitis (71, 26%), gastroschisis (44, 16%), atresia (27, 10%), volvulus (24, 9%), combinations of these diagnoses (46, 17%), aganglionosis (11, 4%), and other single or multiple diagnoses (48, 18%). Prescribed medications included oral antibiotics (207, 76%), H2 blockers (187, 69%), and proton pump inhibitors (156, 57%). Enteral feeding approaches varied among centers; 19% of the cohort received human milk. The cohort experienced 8.9 new catheter-related blood stream infections per 1000 catheter days. The cumulative incidences for enteral autonomy, death, and intestinal transplantation were 47%, 27%, and 26%, respectively. Enteral autonomy continued into the fifth year after study entry. CONCLUSIONS Children with IF endure significant mortality and morbidity. Enteral autonomy may require years to achieve. Improved medical, nutritional, and surgical management may reduce time on PN, mortality, and need for transplantation.

Mechanisms of Disease: update on the molecular etiology and fundamentals of parenteral nutrition associated cholestasis

Since its introduction into clinical practice, parenteral nutrition has revolutionized the care of premature neonates. Serum transaminase and bilirubin levels are commonly elevated in infants on parenteral nutrition, but their normalization is typical in the setting of short-term administration of parenteral nutrition uncomplicated by sepsis. Premature infants who require long-term parenteral nutrition are, however, at severe risk for developing life-threatening hepatic complications. These complications include cirrhosis, liver failure, and the concomitant risks of sepsis, coagulopathy and death. Premature infants and those with short-bowel syndrome are most susceptible to these morbid outcomes. Although it has been more than a quarter of a century since parenteral nutrition was first introduced and its association with hepatic complications described, the precise etiology of parenteral nutrition associated cholestasis (PNAC) remains a mystery; however, our understanding of the molecular components that contribute to PNAC has improved substantially. In this Review, we summarize the fundamentals of PNAC, describe animal models of the disease, review the hepatic bile acid transporters that are crucial for bile acid homeostasis, and define the roles that endotoxin, genetics, and the components of parenteral nutrition are likely to have in the molecular pathogenesis of this life-threatening condition.

High rates of mortality and morbidity occur in infants with parenteral nutrition-associated cholestasis.

BACKGROUND Extremely few data are available about the natural history of parenteral nutrition (PN)-associated cholestasis. The authors evaluated a cohort of infants at a large center to determine the outcome of PN-associated cholestasis in infants with some gastrointestinal function. METHODS The authors reviewed the records of all infants admitted to a level 3 neonatal intensive care unit over a 16-month period who had the diagnosis of PN-associated cholestasis. Records were reviewed in these infants for course of cholestasis, laboratory values, outcome, and infection rate. RESULTS Sixty-six patients were admitted who met the study criteria. There were 10 deaths and 1 referral for liver transplant (Death/TPlant) (17%) in the first year of life. All Death/TPlant infants had at least 1 positive blood culture after the onset of cholestasis. Maximum conjugated bilirubin (MaxCB) in Death/TPlant infants was 15.7 +/- 2.2 (SEM) compared to 8.4 +/- 1.0 mg/dL in babies who recovered. Of 21 infants with a MaxCB > or =10.0, Death/TPlant occurred in 8/21 (38%). Of 40 babies with positive blood cultures, 11 were in the Death/TPlant group vs no deaths among the 25 without positive blood cultures. Average time to resolution from the MaxCB to a CB <2.0 mg/dL was 66 +/- 7 days (n = 49). CONCLUSIONS Infants with PN-associated cholestasis have high rates of mortality despite the presence of some gastrointestinal function. These data support further evaluation and the development of novel forms of therapy for babies with parenteral-associated CB > or =2 mg/dL with emphasis on interventions for infants with a CB >10 mg/dL.

Orthotopic liver transplantation for biliary atresia: The U.S. experience

Biliary atresia is the most common indication for orthotopic liver transplantation (OLT) in the pediatric population. The outcomes of liver transplantation for biliary atresia, however, have not been formally examined on a national scale. The objective of this study was to identify pretransplant variables that predict patient survival after primary liver transplantation for biliary atresia. A cohort of 1,976 pediatric patients undergoing primary liver transplantation for biliary atresia between 1/1988 to 12/2003 was enrolled from the United Network for Organ Sharing database after excluding patients with a history of multiorgan transplant or previous liver transplant. Follow‐up data up to 16 years post‐OLT was available. The 5‐ and 10‐year actuarial survival rates of patients that underwent liver transplantation for biliary atresia in the United States are 87.2% and 85.8%, respectively, and the 5‐ and 10‐year graft actuarial survival rates are 76.2% and 72.7%, respectively. Early deaths (≤90 days post‐OLT) were more often caused by graft failure (P = 0.01), whereas late deaths (>90 days post‐OLT) were more often due to malignancy (P < 0.01). An analysis of outcomes over time demonstrated a decrease in post‐OLT survival and an increase in the number of OLTs done for biliary atresia at an increasing number of centers. A multivariate analysis revealed that cadaveric partial/reduced liver grafts, a history of life support at the time of OLT, and decreased age were independent predictors of increased post‐OLT mortality. In conclusion, OLT is an effective treatment for biliary atresia. Certain pretransplant variables may help predict patient survival following liver transplantation for biliary atresia. (Liver Transpl 2005;11:1193–1200.)

Risk stratification of adult patients undergoing orthotopic liver transplantation for fulminant hepatic failure.

Background. Orthotopic liver transplantation (OLT) is an effective treatment for fulminant hepatic failure (FHF), but postOLT mortality is higher for patients with FHF than for patients with other indications for OLT. In the current study, a large cohort of patients who underwent OLT for FHF was evaluated to develop and validate a system useful for estimating postOLT patient survival. Methods. The 1,457 patients who underwent OLT for FHF in the United States between 1988 and 2003 were enrolled through the UNOS database. This group was divided into a modeling group (n=972) and a crossvalidation group (n=486). With a multivariate regression analysis, the modeling group was used to identify clinical parameters that had a significant association with postOLT survival. This regression analysis was used to create a scoring system that was subsequently assessed in the crossvalidation group. Results. Four risk factors were identified with the multivariate analysis: 1) body mass index ≥30 kg/m2; 2) serum creatinine >2.0 mg/dL; 3) recipient age >50 years old; and 4) history of life support. By assigning points based on the number of risk factors present, the scoring system was able to differentiate between low-risk patients (5-year survival, 81%) and high-risk patients (5-year survival, 42%). The relative risk of postOLT mortality increased by approximately 150% for each additional point. Conclusion. The scoring system risk-stratified the crossvalidation group and accurately predicted postOLT survival. A scoring system utilizing clinical and demographic information readily available prior to OLT may help predict the probability of survival after OLT for FHF.

The pediatric end‐stage liver disease (PELD) model as a predictor of survival benefit and posttransplant survival in pediatric liver transplant recipients

The pediatric end‐stage liver disease (PELD) model accurately estimates 90‐day waitlist mortality for pediatric liver transplant candidates, but it has been unclear if PELD can identify patients who will derive survival benefit from undergoing liver transplantation (LT), if it correlates with posttransplant survival, or if it can identify patients for whom LT would be futile. Pediatric patients who underwent LT between 2001 and 2004 were enrolled through the United Network for Organ Sharing Organ Procurement and Transplant Network database. Survival benefit was measured in terms of life‐years gained during the first year after LT. Complete data were available for 1,247 patients: 53% were listed as Status 1 at the time of orthotopic liver transplantation (OLT), while the remaining 47% had PELD scores. Only in patients with a PELD of 17+ or those designated as United Network for Organ Sharing Status 1 derived a survival benefit within 1 year of LT; patients with a PELD score of ≤16 did not. In addition, a statistically significant association was seen between 1‐year post‐OLT survival and PELD at LT (P = 0.03). No “threshold” PELD score, beyond which risk of post‐LT mortality increased dramatically, was apparent. In conclusion, pediatric patients with a PELD score of 17+ derive survival benefit early after LT, and increasing PELD scores are associated with increasing transplant benefit after liver transplantation. PELD does correlate with posttransplant survival but should not be used as a marker for futility. Liver Transpl 12:475–480, 2006.

Evaluation and management of patients with propionic acidemia undergoing liver transplantation: a comprehensive review.

Abstract:  Propionic acidemia is a rare metabolic disorder that often results in episodic hyperammonemia, basal ganglia infarction, mental retardation, and cardiomyopathy. OLT has been used as a treatment for propionic acidemia, but its benefit in patients with this disease is unclear. The current study was undertaken to clarify the role of OLT in the management of this disease. The medical literature, a national registry of US OLT recipients, and a single institution liver transplant experience were reviewed for cases of OLT for propionic acidemia. Accumulated cases demonstrate that OLT has resulted in clear evidence of clinical improvement in several patients, often obviating the need for dietary restriction or other forms of medical management. OLT appears to halt the decline in neurocognitive function often associated with propionic acidemia. In total, 12 patients with propionic acidemia have undergone a total of 14 OLTs. A quantitative analysis of outcomes shows an overall patient survival rate of 72.2% at one year after OLT. In conclusion, OLT should be considered a treatment option for patients with propionic acidemia who continue to experience episodes of hyperammonemia in spite of maximal medical therapy. Early OLT may limit the development of mental retardation and/or cardiomyopathy.

The natural history of hepatitis C virus in pediatric liver transplant recipients

Although rare in the pediatric population, the natural history of hepatitis C virus (HCV) recurrence in pediatric patients undergoing orthotopic liver transplantation (OLT) for end‐stage liver disease secondary to HCV has not been well described. We performed an analysis of all 67 pediatric patients (<17 years old) who have undergone OLT for HCV in the United States between 1/1988 and 6/2005. The 67 pediatric patients received a total of 83 OLTs for HCV. Following initial OLTs performed for HCV, the patient and allograft survival rates were 71.6% and 55.0%, respectively, at 5 years. Following retransplantation these rates decreased to 55.0% and 33.8%, respectively, following retransplantation. Recipients were listed for retransplantation after 31.3% of all OLTs, and overall recipients were retransplanted after 19.3% of OLTs. The overwhelming majority of retransplants were performed for HCV recurrence. A mean of 1.2 OLTs were performed per patient for HCV. The median time between OLTs for HCV was 290 days. In conclusion, the risk of HCV recurrence in pediatric OLT recipients is high and is associated with a high rate of retransplantation. Still, OLT represents the only treatment option that may achieve long‐term survival in pediatric patients with end‐stage liver disease secondary to HCV that is recalcitrant to medical management. Liver Transpl 12:1119–1123, 2006.

Green tea extract: A potential cause of acute liver failure

The use of herbal products has increased significantly in recent years. Because these products are not subject to regulation by the Food and Drug Administration and are often used without supervision by a healthcare provider, the indication for and consumption of these supplements is quite variable. Moreover, their use is generally regarded as safe and natural by the lay-public. Unfortunately, there has been an increase in the number of reported adverse events occurring with the use of herbal products. We present a case of acute impending liver failure in an adolescent male using a weight-loss product containing green tea extract. Our case adds to the growing concern surrounding the ingestion of green tea extract and serves to heighten healthcare provider awareness of a potential green tea extract hepatotoxicity. Despite the generally touted benefits of green tea as a whole, clinical concern regarding its use is emerging and has been linked to its concentration in multiple herbal supplements. Interestingly, the suspected harmful compounds are those previously proposed to be advantageous for weight-loss, cancer remedy, and anti-inflammatory purposes. Yet, we emphasize the need to be aware of not just green tea extract, but the importance of monitoring patient use of all dietary supplements and herbal products.