Pediatric liver transplantation

Liver transplantation is accepted therapy for acute or chronic liver failure. Advances in preoperative and postoperative management and surgical techniques have extended the indications for transplantation and refined selection, particularly for fulminant hepatic failure. Radiologic techniques, such as magnetic resonance imaging and placement of transjugular intrahepatic portosystemic shunts, have improved preoperative assessment and management. Successful split liver and living related transplantation may reduce waiting list deaths and relieve the organ donor shortage. Auxiliary liver transplantation, although technically difficult, is now accepted management for Crigler-Najjar type I disease but remains controversial for the treatment of organic acidemias and fulminant hepatic failure. Microsurgical techniques have reduced the incidence of postoperative hepatic thrombosis, and radiologic management of portal vein thrombosis and stenosis has decreased operative intervention and improved survival. Immunosuppressive drugs such as cyclosporine microemulsion and tacrolimus have the potential to improve rejection rates and reduce sepsis in the future. There are now good data confirming that long-term survival is achieved with nutritional rehabilitation and good quality of life.

Immunolocalization of OV-6, a putative progenitor cell marker in human fetal and diseased pediatric liver

The existence of progenitor (stem) cells in the human liver remains a matter of debate. In rodent models of hepatocarcinogenesis and injury, oval cells proliferate in the periportal regions of the portal tracts and are suggested to derive from a stem cell compartment, because they are capable of differentiating into hepatocytes or biliary epithelial cells. In this study, the rat oval cell marker, OV-6 has been used to investigate the hypothesis that there are stem cells present in fetal and pediatric human liver. The pattern of OV-6 expression was compared with the established adult biliary cell markers human epithelial antigen-125 (HEA-125) and cytokeratin-19 (CK-19). In normal pediatric liver (n = 7), bile ducts and ductules were immunostained with CK-19 and HEA-125, whereas OV-6 staining was consistently negative. In fetal tissue (n = 10), ductal plate cells, primitive bile ducts, and hepatoblasts were stained with CK-19 and HEA-125 although only some of the ductal plate cells and hepatoblasts were OV-6 positive. In biliary atresia (n = 6) and 1, anti-trypsin deficiency (1,AT) (n = 4), CK-19 and HEA-125 immunostained ductular proliferative cells that tended to form finely anastomosing ductules, whereas OV-6 staining was found more on discrete cells confined to portal tract margins. Additionally, in diseased liver, OV-6 was strongly positive in hepatocyte lobules with greatest intensity in the periseptal regions. This widespread hepatocyte OV-6 positivity suggests that the antibody may identify cells of a less differentiated phenotype (transitional hepatocytes) that have replaced the mature cells. Therefore, it is proposed that in human liver, OV-6 is recognizing cells with a progenitor stem cell-like phenotype with the capacity to differentiate into OV-6 positive ductular cells or lobular hepatocytes.

Population screening for neonatal liver disease: a feasibility study

BACKGROUND

Extra-hepatic biliary atresia and several other causes of neonatal liver disease carry high mortality and morbidity rates, especially if not treated early in life. Despite professional recommendations, delayed referral of infants with prolonged jaundice continues to be a significant problem. One approach to reducing the age of referral and diagnosis is population screening to detect significant conjugated hyperbilirubinaemia as an index of liver dysfunction.

METHODS

To investigate this possibility, and to provide reference data on bilirubin and its conjugated and unconjugated fractions in a normal newborn population, 1157 neonates were anonymously tested (median age 7 days, range 4-28 days) using surplus plasma from routinely collected neonatal screening specimens, using dry slide chemistry.

RESULTS

Of 2310 specimens received, 50% were suitable for analysis. The remainder were either haemolysed or insufficient (10% and 40% of the total, respectively). Total bilirubin concentrations ranged from 9 to 428 micromol/l and conjugated bilirubin from 0 to 175 micromol/l, although the latter was rarely increased to more than 30 micromol/l (2.5th-97.5th percentile ranges 15-285 micromol/l and 0-18 micromol/l, respectively). The range of the percentage of conjugated bilirubin was 0-57% (2.5th-97.5th percentile; range 0-20%).

CONCLUSION

An increased conjugated bilirubin, expressed as a concentration or as the percentage of the total bilirubin, could be used as a specific marker to screen for liver dysfunction in neonates. This approach has the potential to improve the age of referral and the prognosis of infants with neonatal liver disease.

Current results and evolving indications for liver transplantation in children

Liver transplantation continues to be successful and effective treatment for acute and chronic liver failure, and many important lessons have been learned. The development of innovative operative techniques has much reduced the waiting list mortality rate and has extended transplantation to younger and sicker children and to those with functionally normal livers who may benefit from auxiliary liver transplantation. The incidence and range of postoperative complications have improved with increased medical and surgical expertise. As information on long-term outcome for liver transplantation is gained, it is clear that many children will benefit from early elective liver transplantation before the development of significant growth or psychosocial retardation. Early transplantation is also indicated in children with cirrhosis and intrapulmonary shunting or cystic fibrosis with moderate lung disease. During the same period, evolving medical therapy has altered the natural history, patient selection, and timing of transplantation in children with tyrosinaemia type I, primary bile acid disorders, neonatal haemochromatosis, and potentially, cystic fibrosis. It is now clear that children with significant multisystem disease, such as mitochondrial disorders or severe systemic oxalosis, are no longer suitable candidates for liver transplantation. The successful development of liver transplantation has brought good quality life to many children and their families. There are still many lessons to learn and there are future challenges such as the ever-increasing problems of donor scarcity and the search for potent but less toxic immunosuppressive agents.

A single exposure of solar simulated radiation suppresses contact hypersensitivity responses both locally and systemically in humans: quantitative studies with high-frequency ultrasound

Ultraviolet radiation (UVR)-induced suppression of cutaneous cell-mediated immunity plays an important role in the development of photocarcinogenesis in the mouse and a similar role is suspected in humans. Cell-mediated immunity is readily tested in vivo by measuring the contact hypersensitivity (CHS) response to topically applied haptens. CHS in humans is usually determine clinically, with a subjective scoring system. However, these subjective scores cannot be statistically analysed. This paper compares four methods currently used to quantify CHS elicitation responses in humans. The data show that ultrasound images provide the most accurate and reproducible measurements of the clinically observed CHS response. We also demonstrate that assessment of the primary allergic response is a useful indicator of the magnitude of the elicitation response and can be used to avoid severe CHS reactions in volunteers. There are few human studies investigating the effects of solar simulated radiation (SSR) exposure on immunosuppression. In this study we demonstrate SSR is highly immunosuppressive in all subjects tested. Irradiating a small area of skin with a single exposure to 3MEDs of SSR completely suppressed CHS both locally (12/12 volunteers) and systemically (10/12 volunteers). Our data do not support a role for a genetic susceptibility to UVR-induced immunosuppression in humans.

Chronic hepatitis in children after liver transplantation: role of hepatitis C virus and hepatitis G virus infections

BACKGROUND/AIMS

Chronic graft hepatitis occurs in 20-30% adults after liver transplantation but the prevalence and causes in children are not known. In adults, hepatitis C virus infection is prevalent prior to transplantation and recurrent infection is a frequent cause of graft dysfunction. The significance of the recently described hepatitis G virus infection remains unproven. The aim of this study was to examine the role of hepatitis C virus and hepatitis G virus infection in chronic graft hepatitis after paediatric liver transplantation.

METHODS

The prevalence of graft hepatitis and the role of hepatitis C virus and hepatitis G virus infections in 80 children after liver transplantation have been studied, with a median follow up of 4.4 years (range 0.4 to 10.7), and the persistence of hepatitis G infection in the presence of immunosuppression has been determined.

RESULTS

Chronic graft hepatitis was diagnosed in 19/80 (24%) children and was most frequently seen in children transplanted for cryptogenic cirrhosis (71%). There was no significant difference in the prevalence of chronic hepatitis in those transplanted before or after donor anti-HCV screening. Hepatitis C infection occurred in three children transplanted prior to donor screening but in only one was associated with chronic hepatitis. Hepatitis G infection was found in 22/79 (28%) transplant recipients but was not associated with graft hepatitis. In 17/21 children hepatitis G infection persisted for a median of 5.2 years after transplantation.

CONCLUSION

Chronic hepatitis occurred in 24% of children after liver transplantation, a similar prevalence to that in adults. Cryptogenic liver disease predisposed to graft hepatitis, but neither hepatitis C nor hepatitis G infection was associated. Hepatitis G virus caused a frequent and usually persistent infection after transplantation.

Focal reduction of villous blood flow in early indomethacin enteropathy: a dynamic vascular study in the rat

BACKGROUND

Oral indomethacin causes villous shortening, microvascular damage, and distortion, which might induce mucosal ischaemia and necrosis.

AIMS

In order to determine the early events in indomethacin induced jejunal injury we examined the temporal relations between morphological damage and changes in villous blood flow following indomethacin.

METHODS

In anaesthetised rats, mid jejunal villi were exteriorised in a chamber and observed by fluorescence microscopy. Blood flow in surface capillaries was calculated from velocities and diameters. Indomethacin was applied by both luminal and intravenous routes for 90 minutes, after which the animal was perfusion fixed and the villi were processed for histological examination. Control animals received intravenous or luminal bicarbonate (1.25%).

RESULTS

Blood flow slowed in individual villi at 20 minutes, and progressed to complete stasis (in another group) by 45 minutes. Histological examination at 20 minutes revealed microvascular distortion, but no villous shortening; crypt depth:villous height ratios were 0.356 (0.02) in test and 0.386 (0.01) in surrounding villi (p > 0.05). At stasis, the villi under study showed epithelial clumping and were shortened: crypt depth:villous height ratios were 0.92 (0.2) in test and 0.42 (0.06) in surrounding villi (p < 0.02). Vehicle alone had no effect on either blood flow or histology.

CONCLUSIONS

Focal slowing of villous blood flow and microvascular distortion precede villus shortening and epithelial disruption, and indicate that damage to surface microvasculature is an early event in indomethacin induced mucosal injury in this model.

Metabolic liver disease in the pediatric patient

Most metabolic liver diseases that affect pediatric patients present in the neonatal period with either cholestasis or acute liver failure. Metabolic liver disease in the older child has considerable overlap with adult patients. New diagnostic methods and therapy, including liver transplantation, has radically changed the outcome of many metabolic liver diseases.

Liver complications of pediatric parenteral nutrition--epidemiology

Total parenteral nutrition (TPN)-induced liver disease develops in 40-60% of infants who require long-term TPN for intestinal failure. The clinical spectrum includes cholestasis, cholelithiasis, hepatic fibrosis with progression to biliary cirrhosis, and the development of portal hypertension and liver failure in a significant number of children who are totally parenterally fed. The pathogenesis is multifactorial and is related to prematurity, low birth weight, and duration of TPN. The degree and severity of the liver disease is related to recurrent sepsis including catheter sepsis, bacterial translocation, and cholangitis. Lack of enteral feeding leading to reduced gut hormone secretion, reduction of bile flow, and biliary stasis may be important mechanisms in the development of cholestasis, biliary sludge, and cholelithiasis. Although it is unlikely that modern TPN solutions have a major role in the etiology of TPN liver disease, manganese toxicity recently has been recognized in children with hepatic dysfunction on TPN. Although there is a definite relationship with the degree of manganese toxicity and hepatic decompensation, it is not yet clear whether this is a primary mechanism or whether the high levels are related to reduced biliary excretion of manganese. The management strategies for the prevention of TPN-induced liver disease include early enteral feeding, a multidisciplinary approach to the management of parenteral nutrition, and aseptic catheter techniques to reduce sepsis. The administration of ursodeoxycholic acid may improve bile flow and reduce gall bladder and intestinal stasis. As survival from isolated intestinal transplantation improves, this therapeutic option should be considered before TPN liver disease becomes irreversible and combined liver and small bowel transplantation is required.

Axial orthogonal fiber reinforcement in the penis of the nine-banded armadillo (Dasypus novemcinctus)

Examination of histological sections from flaccid and artificially erected nine-banded armadillo (Dasypus novemcinctus) penises confirms that the mammalian corpus cavernosum is the first known biological hydrostat reinforced by collagen fibers arranged at 0 degree and 90 degrees to its long axis. The morphology of this axial orthogonal fiber array affects the mechanical behavior of mammalian penises during erection and copulation. Specifically, the axial orthogonal array gives the erect penis a reproducible shape, maximum size and resistance to tensile, compressive, and bending forces. These features are more appropriate for the mechanical regime associated with copulation than those found in structures reinforced by crossed-helical fibers, although the axial orthogonal array also gives the corpus cavernosum a tendency to fail by kinking. Crimped collagen fibers in the flaccid array as well as three-dimensional folding of the wall in the flaccid corpus cavernosum allow the structure to expand during erection.

Posttransplant growth failure in children

As malnutrition is inevitable in 60% of children with end-stage liver disease, reversal of malnutrition is one of the key aims of liver transplantation. Although good catch-up growth may be achieved in the majority of survivors, persistent growth failure has been noted in 15% to 20% of children. The origin of posttransplant growth failure is complex. It is related to the degree of preoperative malnutrition because children who are severely stunted (height SDS <-1) pretransplant never achieve completely normal growth. Glucocorticoid administration is clearly a major factor because good catch-up growth is achieved on alternate-day steroid regimes or when steroids are discontinued. Significant hepatic dysfunction such as chronic rejection or the development of lymphoproliferative disease that requires alteration in immunosuppressive regimes or prolonged hospitalization may also inhibit linear growth. A less well recognized factor is the development of behavioral feeding problems either before or after transplantation, which reduces adequate oral intake and may be a significant cause of growth failure long term. Important strategies to prevent posttransplant growth failure include early referral for liver transplantation before the development of malnutrition, a multidisciplinary approach to pre- and postoperative nutritional intervention, and the early withdrawal of steroid therapy after transplantation.

Nutritional factors affecting growth before and after liver transplantation

Malnutrition is present in approximately 60% of children at the time of liver transplantation. The pathogenesis of malnutrition is complex and includes reduced calorie intake, fat malabsorption, abnormal nitrogen metabolism, and increased energy expenditure leading to increased calorie requirements. As nutritional status at transplantation is a significant factor in both morbidity and mortality post liver transplantation, intensive nutritional support pre-transplant is vital and may be achieved with a modular feed providing 120-150% estimated average requirement (EAR). Approximately 80% of children who survive liver transplantation will achieve normal growth and nutritional status within 12 months post-transplant. Significant factors responsible for growth failure post-transplant include pre-operative nutritional status (height SDS score <-2), continued glucocorticoid administration, recurrent hepatic dysfunction or chronic rejection and reduced calorie intake due to behavioural feeding problems. Effective future strategies include intensive pre- and post-operative nutritional support and early reduction of glucocorticoid administration.

Progress in pediatric liver transplantation--the Birmingham experience

This report describes the evolution of the Birmingham, UK experience with pediatric liver transplantation from 1983 to present. Two hundred liver grafts were placed in 168 children less than 17 years of age. The current survival rate exceeds 80%.

Clinical features and prognosis of children assessed for isolated small bowel or combined small bowel and liver transplantation

The hepatic histology and clinical status of 37 children on long-term parenteral nutrition (PN) referred for consideration of small bowel transplantation were determined. Seventy five percent of the children had splenomegaly and plasma bilirubin level of greater than 100 mumol/L. All of 21 children who underwent liver biopsy, had increased fibrosis, but only half had established cirrhosis. Thirty-one children were considered to be in need of transplantation (combined liver and bowel transplant, 29; isolated bowel transplant, 2), but only 13 were stable enough to be placed on the transplant list. Seven out of the thirteen children waiting have died because of lack of size-matched organs, and the overall mortality rate of the 37 children was 70%. The main risk factors for death within 6 months were bilirubin level of greater than 100 mumol/L, splenomegaly, and cirrhosis (P = .01). The natural history of PN-associated liver disease is that of progressive liver failure and death 6 to 12 months after onset of cholestasis, defined as bilirubin level of greater than 100 mumol/L. The development of cirrhosis occurs after the onset of jaundice, so early referral may also permit some children to be offered isolated bowel transplantation, which has better outcome than combined liver and bowel transplantation.

Emergency transjugular intrahepatic portosystemic shunt prior to liver transplantation

Transjugular intrahepatic portosystemic shunt (TIPSS) is a new development in the management of severe variceal haemorrhage which has been established in adult patients. We have successfully adapted this technique for children and describe our initial experience in the case of a 9-year-old boy who presented with acute and chronic liver failure and uncontrollable life-threatening bleeding from oesophageal and gastric varices, despite intensive medical management including sclerotherapy. A 10-mm TIPSS was successfully placed with immediate reduction in portal pressure and cessation of variceal bleeding. The patient's condition stabilised sufficiently for him to undergo liver transplantation 2 days later, at which time the TIPSS was patent.

Risk factors for liver rejection: evidence to suggest enhanced allograft tolerance in infancy

After liver transplantation, a relatively low intensity immunosuppressive regimen is employed in our unit: after initial triple therapy (prednisolone, azathioprine, cyclosporin), prednisolone is discontinued at three months and azathioprine at one year. A retrospective study was therefore performed to determine the incidence of rejection, and to identify risk factors for rejection in our patient population. Over a 10 year period, 135 transplants were performed on 109 children. Thirty four (25%) were on infants less than 1 year old. Incidences of acute rejection and irreversible chronic rejection were calculated for grafts surviving more than one and four weeks respectively. Acute rejection occurred in 51 of 101 allografts (50%), and irreversible chronic rejection in 11 of 91 allografts (12%). The immunosuppression strategy was not associated with an increased incidence of rejection. Acute rejection occurred in only eight of 28 allografts (29%) in those transplanted during their first year, compared with 43 of 73 (59%) in older children. Logistic and Cox regression analysis supported age at transplantation as a significant risk factor for acute rejection. Irreversible chronic rejection did not occur in any of 24 grafts in patients transplanted before one year, compared with 11 of 67 (16%) in older recipients. This suggests possible enhanced allograft tolerance with transplantation during the first year of life. This unexpected and potentially important finding now requires confirmation in other large patient series, with blind interpretation of post-transplant liver biopsies.

Effect of vitamin E deprivation and exercise training on induction of HSP70

To investigate the effect of dietary vitamin E deprivation and chronic exercise on the relative content of selected isoforms of the heat-shock protein 70 (HSP70) family in rat hindlimb muscle, vitamin E was withheld for 16 wk from female rats that underwent treadmill run training during the final 8 wk. As indicated by increased (P < 0.05) content of the stress-inducible isoform (HSP72), training did stress the exercising muscles. However, vitamin E deficiency did not alter HSP72 content in nontrained rats and was associated with a lesser induction (P < 0.01) in some muscles of trained animals. The constitutive isoform, which exhibited similar levels in muscles of varying fiber types, was demonstrated to be largely refractory to exercise, with an equivocal response to vitamin E deprivation. HSP72 content was correlated to type I myosin heavy chain (MHC-I) content but only in muscles of sedentary normal-diet rats. After training, HSP72 content in a muscle essentially devoid of MHC-I (superficial vastus lateralis) reached levels comparable to those in a muscle high in MHC-I (soleus).

Hepatitis C infection after blood product transfusion

HCV infection has been demonstrated in multiply transfused children who received blood products or transplanted organs before universal screening in 1990. The risk of active infection is related to the number of transfusions or pooled blood products. Accurate diagnosis of infection is dependent on utilisation of third generation RIBA and identification of HCV RNA by RT-PCR. The natural history of HCV in childhood is undetermined and prospective long term studies should be undertaken. It is likely that about develop chronic hepatitis with progression at some time to cirrhosis and have an increased risk of developing liver cancer. Treatment with interferon alfa may be effective in up to 50% of children and only those children with documented infection with HCV RNA should be selected for treatment. In order to answer important questions about natural history, outcome, and the necessity and efficacy of treatment response, treatment for these children should only be as part of scientifically conducted studies on a multicentre basis.

Unresectable hepatic tumors in childhood and the role of liver transplantation

Liver transplantation has been performed in five children with unresectable hepatic tumors who did not have extrahepatic metastases at the time of surgery. Two of the children had hepatoblastomas, one had an infantile hemangioendothelioma, and two had a hepatoma. The two children who had hepatoblastoma are well (37 and 25 months posttransplant) and have no evidence of recurrence. The child with infantile hemangioendothelioma had a successful operation, with good quality of life, but died of tumor recurrence 41 months after transplantation. Both children with hepatomas died, one of graft failure owing to chronic rejection and the other of tumor recurrence 5 months posttransplant. These results suggest that liver transplantation may be successful in children with unresectable hepatic tumors without extrahepatic spread and should be considered particularly for the treatment of hepatoblastoma.

Transplantation for end stage liver disease related to alpha 1 antitrypsin

Alpha 1 antitrypsin deficiency (AT) is an autosomal recessive disease associated with chronic liver disease in adults and children and emphysema in adults. The disease is one of the most common inherited disorders of the Caucasian population of North Europe and North America and is the most common genetic reason for pediatric orthotopic liver transplantation (OLTx), although it is a rare indication in adults. The natural history of the disease is unpredictable and the pathogenesis of the liver injury unclear. Thirty-five patients with histologically apparent alpha 1 AT accumulation in the liver (22 adults, 13 children) have been transplanted in this center. Clinical features were correlated with the pretransplant phenotype, serum alpha 1 antitrypsin levels and potential precipitating factors. All children were PiZZ homozygotes, most of whom had presented with neonatal hepatitis. The majority of adult patients were heterozygotes presenting with portal hypertension and liver cirrhosis. Current one-year posttransplant survival figures are 73% for adults and 87.5% for children. Replacement of the cirrhotic liver results in acquisition of the donor phenotype, a rise in serum levels of alpha 1 antitrypsin, and apparent prevention of associated disease.

Bone fractures in children undergoing orthotopic liver transplantation

This retrospective study documents the incidence and distribution of fractures in 117 children with end-stage liver disease who underwent orthotopic liver transplantation (OLT) over a 6-year period (1987-1993). Both the pre- and post-OLT phases were included. Nineteen children (16.2 %) sustained a total of 69 fractures. Age at time of fracture ranged from 3 months to 9 years 8 months (median 13.5 months). There was no documented trauma in 14/19 cases. Metabolic bone disease, assessed qualitatively on plain radiographs, was present in 17/19 children at the time of fracture. This took the form of rickets (n = 3), osteopenia (n = 12) and osteosclerosis (n = 2). Potential risk factors including pre-existing metabolic bone disease, drugs and immobilization were assessed. The findings emphasise the need for clinical and radiological awareness of the fracture risk, particularly during the peri-transplant period when this risk may be greatest.