Classification and genetic features of neonatal haemochromatosis: a study of 27 affected pedigrees and molecular analysis of genes implicated in iron metabolism

Neonatal haemochromatosis (NH) is a severe and newly recognised syndrome of uncertain aetiology, characterised by congenital cirrhosis or fulminant hepatitis and widespread tissue iron deposition. NH occurs in the context of maternal disease including viral infection, as a complication of metabolic disease in the fetus, and sporadically or recurrently, without overt cause, in sibs. Although an underlying genetic basis for NH has been suspected, no test is available for predictive analysis in at risk pregnancies. As a first step towards an understanding of the putative genetic basis for neonatal haemochromatosis, we have conducted a systematic study of the mode of transmission of this disorder in a total of 40 infants born to 27 families. We have moreover carried out a molecular analysis of candidate genes (beta(2)-microglobulin, HFE, and haem oxygenases 1 and 2) implicated in iron metabolism. No pathogenic mutations in these genes were identified that segregate consistently with the disease phenotype in multiplex pedigrees. However, excluding four pedigrees with clear evidence of maternal infection associated with NH, a pedigree showing transmission of maternal antinuclear factor and ribonucleoprotein antibodies to the affected infants, and two families with possible matrilineal inheritance of disease in maternal half sibs, a large subgroup of the affected pedigrees point to the inheritance of an autosomal recessive trait. This included 14 pedigrees with affected and unaffected infants and a single pedigree where all four affected infants were the sole offspring of consanguineous but otherwise healthy parents. We thus report three distinct patterns of disease transmission in neonatal haemochromatosis. In the differentiation of a large subgroup showing transmission of disease in a manner suggesting autosomal recessive inheritance, we also provide the basis for further genome wide studies to define chromosomal determinants of iron storage disease in the newborn.

Bile bilirubin pigment analysis in disorders of bilirubin metabolism in early infancy

BACKGROUND

Early and accurate diagnosis of Crigler-Najjar syndrome, which causes prolonged unconjugated hyperbilirubinaemia in infancy, is important, as orthotopic liver transplantation is the definitive treatment.

AIM

To determine whether bilirubin pigment analysis of bile in infants with prolonged unconjugated hyperbilirubinaemia provides useful diagnostic information in the first 3 months of life.

METHODS

Retrospective review of patients with prolonged unconjugated hyperbilirubinaemia referred to the liver unit, Birmingham Children's Hospital, for the diagnosis of Crigler-Najjar syndrome. Bile bilirubin pigment composition was determined by high performance liquid chromatography. Initial diagnoses were made based on the result of bile bilirubin pigment composition. Final diagnoses were made after reviewing the clinical course, response to phenobarbitone, repeat bile bilirubin pigment composition analysis, and genetic studies.

RESULTS

Between 1992 and 1999, nine infants aged less than 3 months of age with prolonged hyperbilirubinaemia underwent bile bilirubin pigment analyses. Based on these, two children were diagnosed with Crigler-Najjar syndrome (CNS) type 1, six with CNS type 2, and one with Gilbert's syndrome. Five children whose initial diagnosis was CNS type 2 had resolution of jaundice and normalisation of serum bilirubin after discontinuing phenobarbitone, and these cases were thought to be normal or to have Gilbert's syndrome. One of the initial cases of CNS type 1 responded to phenobarbitone with an 80% reduction in serum bilirubin consistent with CNS type 2. In all, the diagnoses of six cases needed to be reviewed.

CONCLUSIONS

Early bile pigment analysis, performed during the first 3 months of life, often shows high levels of unconjugated bilirubin or bilirubin monoconjugates, leading to the incorrect diagnosis of both type 1 and type 2 Crigler-Najjar syndrome.

Immunosuppressive drugs in paediatric liver transplantation

Orthotopic liver transplantation is established treatment for children with acute and chronic liver failure. Despite advances in pre- and postoperative management, innovative surgical techniques and new immunosuppressive drugs, acute and chronic rejection remains a problem. In addition, well established adverse effects of commonly used immunosuppressive drugs are no longer accept able. More potent, but less toxic, immunosuppressive agents have been developed and some novel compounds are now entering routine practice. Cyclosporin was the cornerstone of immunosuppressive therapy until the introduction of its novel pharmaceutical form (Neoral) with improved bioavailability, lower inter- and intraindividual pharmacokinetic variability and improved graft survival. Recently, tacrolimus, a macrolide drug with a similar mode of action, but much higher potency, was introduced and, at present, is the only agent which can successfully replace cyclosporin as a first-line immunosuppressive drug. Mycophenolate mofetil has recently been approved for use in adult and paediatric renal transplant recipients. It has a similar mode of action to cyclosporin and tacrolimus, but acts at a later stage of the T cell activation pathway. Administration with standard immunosuppressive drugs reduces the incidence of acute rejection and enables cyclosporin and tacrolimus dose reduction, thus reducing the risk of associated toxic effects. Phase I and II trials with sirolimus (rapamycin), a macrolide antibiotic, have shown comparable immunosuppressive action, when administered in conjunction with standard immunosuppressants. Further clinical trials need to be carried out to establish efficacy, tolerability and pharmacokinetics in paediatric transplant recipients. Monoclonal antibody therapy (daclizumab and basiliximab) is an exciting new development whereby T cell proliferation is inhibited by selective blockade of interleukin (IL)-2 receptors. Preliminary results, when used in combination with a standard immunosuppressive regimen, are good with respect to incidence of acute graft rejection, host immune response and adverse effects. FTY720 is a novel synthetic immunosuppressive compound which induces a reduction in peripheral blood lymphocyte count through apoptotic T cell death or accelerated trafficking of T cells into lymphatic tissues. Experimental animal studies demonstrated synergistic action in combination with low dose cyclosporin or tacrolimus, potentiating their immunosuppressive effects. Further studies are being carried out to determine its potential for application in organ transplantation. Despite this rapid development of novel compounds, it will take many years before they may become part of standard protocols in paediatric transplantation medicine. Further development and research of efficacy and tolerability of existing drugs is, therefore, vital.

Human hepatic stem-like cells isolated using c-kit or CD34 can differentiate into biliary epithelium

BACKGROUND & AIMS

Recent reports suggest that after bone marrow transplantation into rodents and humans, hematopoietic stem cells migrate into the liver and give rise to oval cells, hepatocytes, and biliary epithelial cells. We investigated this hypothesis further in the human liver using the hematopoietic markers c-kit and CD34.

METHODS

Immunofluorescence confocal microscopy was performed using cytokeratin 19 (CK-19; biliary cell marker) with either c-kit or CD34. Immunomagnetic separation was then used to select c-kit- or CD34-positive cells. After attachment, cells were cultured for up to 7 days, and their growth and phenotypic characteristics were examined.

RESULTS

In cirrhotic tissue, c-kit- or CD34-positive cells were located in the portal tracts surrounding bile ducts. Occasionally c-kit- (but not CD34-) positive cells that coexpressed CK-19 were observed integrated into bile ducts. In vitro, immunoisolated c-kit or CD34 cells gave rise to colonies of at least 2 morphologies expressing CK-19 or CD31 (endothelial cell marker). CD34- or c-kit-positive cells with similar properties were also isolated from normal liver.

CONCLUSIONS

These findings indicate that cells present in human liver that express the markers c-kit or CD34 have the capacity to differentiate into biliary epithelial cell lineage and may therefore represent human biliary epithelial progenitor cells.

Combined liver-kidney transplantation for primary hyperoxaluria type 1 in young children

BACKGROUND

Primary hyperoxaluria type 1 (PH1) is a rare condition in which deficiency of the liver enzyme alanine:glyoxylate aminotransferase leads to renal failure and systemic oxalosis. Combined liver-kidney transplantation (LKT) is recommended for end-stage renal failure (ESRF) in adults, but management of infants and young children is controversial. We retrospectively reviewed six children who underwent LKT for PH1.

METHODS

The median age at diagnosis was 1.8 years (range 3 weeks to 7 years). Two children presented with severe infantile oxalosis at 3 and 9 weeks, five patients had ESRF with nephrocalcinosis and systemic oxalosis, (median duration of dialysis 1.3 years), and one had progressive chronic renal failure. Four children underwent combined LKT, one child staged liver then kidney, and one infant had an isolated liver transplant. The median age at transplantation was 8.9 years (range 1.7-15 years).

RESULTS

Overall patient survival was four out of six. The two infants with PH1 and severe systemic oxalosis died (2 and 3 weeks post-transplant) due to cardiovascular oxalosis and sepsis. The other four children are well at median follow-up of 10 months (range 6 months to 7.4 years). No child developed hepatic rejection and all have normal liver function. Renal rejection occurred in three patients. Despite maximal medical management, oxalate deposits recurred in all renal grafts, contributing to graft loss in one (one of the infants who died), and significant dysfunction requiring haemodialysis post-transplant for 6 months.

CONCLUSIONS

LKT is effective therapy for primary oxalosis with ESRF but has a high morbidity and mortality rate in children who present in infancy with nephrocalcinosis and systemic oxalosis. We feel that earlier LKT, or pre-emptive liver transplantation, may be a better therapeutic strategy to improve the outlook for these patients.

Investigation and outcome of neonatal hepatitis in infants with hypopituitarism

Congenital hypopituitarism is a recognized cause of neonatal hepatitis, but the diagnosis may be difficult to establish even if clinically suspected. In order to determine the natural history of this disorder, the outcome of 12 infants with neonatal hepatitis secondary to hypopituitarism is reviewed. The clinical diagnosis of hypopituitarism was established on a combination of features, which include dysmorphism (4 infants), optic nerve hypoplasia (8 infants), micropenis (5 male infants) and recurrent hypoglycaemia (blood glucose < 2.4 mmol/l (8 infants)). Endocrine investigation revealed low free thyroxine (T4) levels (< 10 pmol/l), with normal thyroid stimulating hormone (TSH) levels (0.4-4.5 mU/l) (11 infants), and serum cortisol levels which were inappropriately low (< 200 nmol/l). In 9 of 12 infants, liver disease resolved within 6 wk following treatment with thyroxine, hydrocortisone and, where appropriate, growth hormone, including Cases 9 and 1 in whom diagnosis and treatment were delayed until 3 mo and 3 y of age, respectively. Liver disease resolved spontaneously in two infants prior to starting hormone replacement therapy (Cases 11, 12), and one male infant (Case 10), in whom the diagnosis and hormone replacement therapy were delayed until 5 y of age, developed cirrhosis and portal hypertension and later underwent liver transplantation.

CONCLUSION

The diagnosis of hypopituitarism should always be considered in infants with unexplained neonatal hepatitis. Delay in diagnosis and appropriate treatment was associated with persistently abnormal liver function tests and may lead to irreversible liver disease.

Anatomy of the baculum-corpus cavernosum interface in the norway rat (Rattus norvegicus), and implications for force transfer during copulation

The baculum is a nonappendicular bone found in the glans tissue of members of five orders of mammals. Its function during copulation is unknown. Anatomical examination of the baculum and corpus cavernosum in the Norway rat (Rattus norvegicus) shows that the two structures are connected by a layer of fibrocartilage, and that the distal tip of the corpus cavernosum swells during erection to surround the proximal end of the baculum. Microradiographs of bacula from sexually experienced males show that regions of the bone may be remodeling; these data suggest that the baculum is load-bearing. On the basis of this anatomy, I propose that the baculum increases the overall flexural stiffness of the penis during copulation by transferring bending and compressive forces from the distal end of the glans to the tensile wall of the corpus cavernosum. Forces on the distal end of the penis during copulation press the baculum against the corpus cavernosum, reducing its internal volume and increasing intracavernosal pressure and corpus cavernosum wall strains. Because the wall of the erect corpus cavernosum is reinforced with inextensible collagen fibers, an increase in wall strain will also increase wall tissue stiffness, and thereby increase the flexural stiffness of the corpus cavernosum.

Long-term nutritional and neurodevelopmental outcome of liver transplantation in infants aged less than 12 months

BACKGROUND

Liver transplantation is established treatment for children with end-stage liver disease and has a 5-year survival rate of 80% to 85%, even in infants under 12 months. Long-term outcome in nutritional rehabilitation and normal development is unknown. This study aimed to prospectively evaluate growth and psychoneurologic performance of children who undergo liver transplantation in infancy.

METHODS

Twenty-five infants (18 girls, 7 boys) who underwent liver transplantation at less than 12 months of age (median age, 9 months) were evaluated for 4 years. Growth measurements were expressed as standard deviation scores (SDSs; mean +/- SEM), and psychoneurologic performance was assessed with the unrevised Griffiths Mental Ability Scales (normal range, 80-120).

RESULTS

Four children died during the study (4-year survival, 84%). The children were malnourished before transplantation (SDSs: weight, -1.9 +/- 0.2; midarm muscle area, -0.93 +/- 0.3; midarm fat area, -1.52 +/- 0.3; and height, -0.95 +/- 0.3). Nutritional rehabilitation for all parameters occurred within 12 to 24 months after transplantation, which was most significant for weight (-1.1 +/- 0.2, P = 0.001), midarm muscle area (0.74 +/- 0.3, P = 0.001), and midarm fat area (-0.44 +/- 0.3, P = 0.01). There was some improvement in height (-0.72 +/- 0.3, P = 0.14), which was not significant, although infants who were severely stunted before transplantation (mean height standard deviation score [SDS] -2.46) showed significant catch-up at 1 year after transplantation (mean height SDS -1.2, P = 0.003). Psychoneurologic scores were within normal limits before transplantation and were maintained for the 4-year follow-up period, although individual scores varied during this period. Improved nutritional status was associated with increased muscle bulk and subsequent improvement in motor scores from 90.6 at initial assessment to 97.3 at 4 years (P = 0.28). There was a temporary reduction in social skills and eye-hand coordination in the first year, which may have been an effect of the hospital environment or cyclosporine immunosuppression. Language abilities also regressed during the first year, possibly related to the effect of nasogastric tube feeding in delaying normal speech development.

CONCLUSIONS

Liver transplantation in infancy has not only a successful outcome but is also associated with long-term catch-up growth and nutrition and maintenance of normal development.

En block combined reduced-liver and small bowel transplants: from large donors to small children

BACKGROUND

The critical shortage of size-matched donor organs for infants and small children in need of combined liver and intestinal transplantation has lead to long waiting times and a high risk of dying before transplantation. Utilizing grafts from larger donors could alleviate this problem, but using larger composite grafts in small children has been challenging and unsuccessful in the past.

METHODS

We conducted a pilot study for evaluating the results of transplanting into small recipients a composite graft (reduced-size liver and whole small bowel, including duodenum and pancreas head) procured from large donors. Liver size reduction was performed ex situ using the extrahilar approach, which leaves the liver hilum untouched. Straightforward implantation of the graft was performed by simple, two-step vascular anastomoses. The preservation of the donor duodenum in continuity with the combined graft avoided the need for biliary reconstruction, thus preserving maximal bowel length for gut continuity restoration in the recipient.

RESULTS

Two children, weighing 7.6 and 9.8 kg, respectively, underwent transplantation of a composite graft procured from donors weighing 35 kg. Their waiting time (68 and 97 days, respectively) was shorter compared with our previous experience with conventional techniques. Both are currently alive and well, at home and on full enteral feeds, 15 and 11 months after transplantation, respectively.

CONCLUSION

This new technique has extended the range of possible donors for small candidates waiting for combined grafts and was successful in two patients. It should be considered for small recipients in the future.

The frequency and outcome of biliary atresia in the UK and Ireland

BACKGROUND

Biliary atresia is an obliterative cholangiopathy of infancy that is fatal if untreated. Surgical treatment, the Kasai portoenterostomy, may restore bile flow and clear jaundice, and, if successful, achieve a 10-year survival of 90% with a native liver. The outcome of a 2-year cohort of children with biliary atresia in the UK and Ireland was assessed to find the current frequency, the factors influencing outcome, and the medium-term need for liver transplantation.

METHODS

Cases diagnosed between March, 1993, and February, 1995, were notified by paediatricians to the British Paediatric Surveillance Unit via a monthly reporting system. Confirmed cases were followed up by postal questionnaires to notifying paediatricians.

FINDINGS

93 cases were confirmed, a frequency of 1/16700 livebirths. Primary surgery was done in 91 children in 15 surgical centres with an early success rate for clearing jaundice of 55% overall. Centres were grouped according to caseload; group A had more than 5 cases/year and group B fewer than 5 cases/year. Early success was higher in group-A centres, odds ratio 2.02 (95% CI 0.86-4.73), but this did not reach statistical significance. Of 41 children in whom surgery was unsuccessful in clearing jaundice 9 (22%) died and 30 (73%) underwent liver transplantation. Survival without liver transplantation and overall survival were both significantly greater in group-A centres, rate ratios 0.48 (95% CI 0.27-0.86) and 0.32 (0.11-0.94). Actuarial 5-year survival without transplantation was 61.3% in group-A centres and 13.7% in groupB centres. Actuarial 5-year overall survival was 91.2% in group A and 75% in group B. Once centre size was taken into account, no other factor, including age at surgery, was predictive of survival without transplantation or overall survival.

INTERPRETATION

The outcome of children with biliary atresia is related to the caseload of the surgical centre where they have their primary surgery. Children with biliary atresia should be managed in surgical centres with a caseload of more than five cases annually.

Indications and outcome of liver transplantation in tyrosinaemia type 1

A retrospective analysis was performed on 17 patients presenting with tyrosinaemia type 1 (TT1) between 1989-1997; 7 pre 1992 prior to the introduction of 2-(2-nitro-4-trifluoromethylbenzoyl)-1, 3-cyclohexanedione (NTBC) therapy and 10 post 1992. During this time, eight children (5 males) underwent orthotopic liver transplantation (OLT); six prior to the introduction of NTBC in 1992 and two on NTBC therapy. The primary indications for OLT pre-1992 were risk of hepatocellular carcinoma with evidence of hepatic dysplasia in all, associated with liver failure in two, and rise in alpha-fetoprotein (AFP) in four. Two of the ten treated with NTBC required OLT. The indications were non-response to NTBC in one child and development of hepatic dysplasia associated with poor quality of life in the second patient. Median age for OLT was 64 months (range 5-127 months) with a median weight of 24 kg (range 6-25 kg). The histology of hepatectomy specimens at transplantation showed: cirrhosis in 8, hepatic dysplasia in 6 and hepatocellular carcinoma in 1. Plasma tyrosine and AFP returned to normal in all cases. Urinary succinylacetone reduced but persisted in small amounts (median 7.7 micromol/mmol creatinine). Hypertrophic cardiomyopathy resolved in 3/3 patients. Hypoglycaemia, not responding to dietary therapy or NTBC treatment, resolved post-transplant in one patient. There were two deaths, one from primary non-function and one from chronic rejection. Late complications in survivors (n=6) include post-transplant lymphoproliferative disease of the iris in one child which resolved and renal dysfunction with a fall in glomerular filtration rate in three (50%). Median follow up post OLT is 6.7 years (range 1-7 years). Quality of life post-transplant in survivors is good with unrestricted diet in all.

CONCLUSION

Liver transplantation is an effective treatment for TT1 with good quality of life. The current indications of OLT in TT1 are non-response to NTBC, risk of malignancy and poor quality of life related to dietary restriction and frequency of blood sampling.

Outcome of liver retransplantation in children

Irreversible liver graft failure is a life-threatening complication. We reviewed the first 200 pediatric liver transplantations in Birmingham. Forty-one children developed primary graft failure, 9 of whom developed secondary graft failure. The main indications for graft failure were primary nonfunction (PRNF; 8 patients), vascular complications (VASC; 23 patients), and chronic rejection (CHRE; 19 patients). Thirty-two children underwent retransplantation (ReTx) (21 children received reduced grafts; 11 children, whole hepatic grafts). Patient survival was significantly worse for retransplant recipients compared with children receiving a single graft (63% v 76. 5% actuarial patient survival at 1 year; P <.05). Primary graft 1-year actuarial survival was 74% in first grafts compared with 47% for regrafts (P <.05), but improved with time. The graft 1-year survival rate was 55% for whole grafts and 45% for reduced and/or split grafts in the first 100 grafts compared with 83% and 66% in the second 100 grafts, respectively (P <.01). Emergency ReTx within a month of transplantation was associated with more complications and a worse outcome (1-year survival rate, 37%) compared with patients who underwent ReTx later (1-year survival rate, 72%; P <. 01). The incidence of primary graft failure decreased from 33% in the first 100 grafts to 16% in the second 100 grafts (P <.01), as did the incidence of PRNF, which decreased from 8% to 0% (P <.05). Although the rates of graft failure from VASC decreased from 15% to 8% (P =.2) and CHRE decreased from 11% to 8% (P =.6), neither reached statistical significance. The improved results overall are because of advances in surgical techniques, intensive care management, and graft preservation and refinements in immunosuppression. We conclude that ReTx for a child with primary graft failure is justified.

Expression of the stem cell factor receptor c-kit in normal and diseased pediatric liver: identification of a human hepatic progenitor cell?

The stem cell factor (SCF)/c-kit ligand/receptor system has been implicated in stem (oval) cell activation following liver injury in the rat. The aim of this study was to determine the role of the SCF/c-kit system in pediatric human liver during acute and chronic liver injury. Tissue was obtained from hepatectomy specimens of patients undergoing liver transplantation for extrahepatic biliary atresia (EHBA) and fulminant hepatic failure (FHF). Specific expression of mRNA for c-kit and beta-actin was measured by ribonuclease protection and by immunohistochemistry to localize c-kit in tissue sections. Expression of c-kit was detected at relatively consistent levels in normal and cirrhotic (EHBA) livers. However, in FHF, c-kit mRNA levels were elevated in 3 of 6 specimens. Immunolocalization highlighted the presence of small numbers of c-kit-positive cells in the portal tracts of normal livers with increased numbers in cirrhotic livers. The highest c-kit staining, however, was observed in FHF, in which, in addition to the cells in the portal tracts, discrete c-kit-positive cells were also found integrated into bile ducts. Colocalization studies demonstrated some of the c-kit-positive cells to be of mast cell, leukocyte, and hematopoietic cell origin. However, there remained a subset that was also negative for these markers. The up-regulation of c-kit receptor expression in diseased livers suggests an involvement of this receptor/ligand system in hepatic repair mechanisms, and we speculate that c-kit-positive cells may represent a hepatic progenitor cell population. The origin and growth/differentiation potential of these c-kit-positive cells is under investigation.

Comparison of pharmacokinetics of Neoral and Sandimmune in stable pediatric liver transplant recipients

Cyclosporine (Sandimmune; Novartis Pharmaceuticals UK Ltd) is an effective immunosuppressive drug, but its lipid formulation and variable absorption may expose children to the risk of rejection during episodes of gastroenteritis after liver transplantation. Neoral (Novartis) is a microemulsified form of cyclosporine that may be better absorbed. In this study, the pharmacokinetic profiles of Neoral and Sandimmune were compared in stable children after liver transplantation to evaluate whether Neoral is more predictably absorbed. Eight children, 6 boys and 2 girls, with a mean age of 4.5 years (range, 1.2-12) were studied between 4 and 12 months after liver transplantation. Pharmacokinetic profiles were performed on each child by using the same dose (mg/kg) of Neoral or Sandimmune. Tmax, Cmax, Ctrough, and the area under the curve (AUC) were calculated and side effects were documented in children taking either drug for more than 3 months. Mean peak cyclosporine levels were higher and were achieved significantly sooner with Neoral (Cmax 790.5 +/- 216.5 ng/mL, P =.06; Tmax 1.8 +/- 1.0 hr, P =.01) than with Sandimmune (Cmax 589.4 +/- 313 ng/mL, Tmax 2.5 +/- 1.7 hr), implying more rapid and better absorption. There was no significant difference in overall drug exposure (AUC) and 12-hour trough levels between the two formulations (P >.05). Children with Roux-en-Y loop biliary anastomosis taking Neoral, however, showed greater increases in AUC (mean increase = 37%) than those with duct-to-duct anastomosis (mean increase = 16%). There was no correlation between 12-hour trough level and AUC for either Neoral (r2 = 0.48) or Sandimmune (r2 = -0.08); however, for both drugs, AUC correlated very well with the 2-hour post-dose level (r2 = 0.68 and 0.7, respectively). Hirsutism was reported in 4 of 6 children on Neoral and may be associated with higher peak levels. Neoral is more consistently absorbed than Sandimmune in children after liver transplantation and may be more effective prophylaxis against rejection. Because of the increased peak levels and drug exposure, which may influence side effects, particularly in children with Sandimmune malabsorption, we recommend a 1:0.75 dose conversion ratio in patients being converted from Sandimmune to Neoral.

Expansion of the tunica albuginea during penile inflation in the nine-banded armadillo (Dasypus novemcinctus)

Artificial inflation of corpora cavernosa from the nine-banded armadillo (Dasypus novemcinctus) showed that the expansion of the tunica albuginea during erection increases both components of flexural stiffness: the second moment of area and Young's modulus of elasticity. Folded tissue and crimped collagen fibers in the tunica albuginea permit its expansion during erection. As the tunica albuginea's radii increase in size, its second moment of area also increases. The crimped collagen fibers permit the flaccid tunica albuginea to expand to strains of 25 % longitudinally and 15 % circumferentially, after which tissue stiffness increases by 3–4 orders of magnitude. Radial expansion of the corpus cavernosum is limited by collagenous trabeculae. The trabeculae maintain the non-circular cross section of the corpus cavernosum during erection. Restricting expansion appears to protect the corpus spongiosum and urethra from occlusion, but has the side effect of reducing the potential flexural stiffness of the corpus cavernosum by reducing the second moment of area of the tunica albuginea.

Acute liver failure

Acute liver failure is a rare but potentially fatal disease. Adult definition of fulminant hepatic failure, which includes the development of hepatic necrosis and encephalopathy within 8 weeks of onset of liver disease does not apply to acute liver failure in children particularly if secondary to autoimmune or metabolic liver disease. The etiology of acute liver failure varies with the age of the child. In neonates, infection or an inborn error of metabolism are common, while viral hepatitis and drug induced liver failure are more likely in older children. The clinical presentation of acute liver failure includes jaundice, coagulopathy and encephalopathy. In neonates, encephalopathy may be subclinical. The management of acute liver failure includes assessment of prognosis for liver transplantation; prevention and treatment of complications while awaiting hepatic regeneration or a donor liver and hepatic support. The major complications of acute liver failure are sepsis, gastro-intestinal bleeding, cerebral edema, renal and cardiac failure. Selection for liver transplantation depends on the etiology of the disease, prognostic factors, the presence or absence of multisystem disease and/or reversible brain damage. Prognostic factors for survival are less well established in children than in adults but children with metabolic liver disease, prothrombin time > 50 seconds, rising bilirubin and falling transaminase, grade II or higher grade of hepatic coma indicate poor prognosis. Most children receive a reduced or split liver graft. Living related donations for acute liver failure are also carried out by some centres. Survival post liver transplantation for acute liver failure has improved and most recipients can expect a 70% five year survival.

Cholestasis and end-stage liver disease

Protein-energy malnutrition is an inevitable consequence of chronic liver disease, particularly in the developing infant. Severe malnutrition with loss of fat stores and muscle wasting affects between 60% and 80% of infants with liver disease (Beath, 1993a; Holt et al, 1997). Reduced energy intake secondary to anorexia, vomiting and fat malabsorption, in association with a disordered metabolism of carbohydrate and protein, increased energy requirements and vitamin and mineral deficiencies, contributes towards growth failure. Reversal of malnutrition is one of the key aims of liver transplantation and is achieved in the majority of long-term survivors. The aetiology of persistent growth failure post-transplantation is multifactorial and is related to pre-operative malnutrition, glucocorticoid administration, feeding problems and post-operative complications. Strategies to prevent pre- and post-transplant growth failure include early referral for liver transplantation and a multidisciplinary approach to nutritional support, which may increase survival and improve the quality of life and outcome of liver transplantation.

Efficacy of Neoral in the immediate postoperative period in children post-liver transplantation

Cyclosporine (Sandimmune) is an effective immunosuppressive drug but may be poorly absorbed in the early postoperative period after liver transplantation, exposing the recipient to an increased risk for rejection. Neoral is a new oral formulation of cyclosporine that uses a mixture of surfactant, lipophilic, and hydrophilic solvents to permit microemulsification that leads to potentially better absorption. This oral drug has not been evaluated in children immediately posttransplantation. The aim of this study was to evaluate the pharmacokinetics, bioavailability, and safety of Neoral during the first week post-liver transplantation in children. Twelve children, 8 boys and 4 girls, with a median age of 2.6 years (range, 1 to 8 years) were administered Neoral within 12 hours posttransplantation. Pharmacokinetic profiles were performed over a 12-hour period on each child on days 1, 3, and 5 and twice-daily trough levels were obtained on days 2, 4, 6, and 7. The maximum concentration (Cmax), time to reach Cmax (Tmax), 12-hour trough levels, and area under the curve were calculated, and rejection episodes and adverse events were documented over a 12-week period. Neoral was well absorbed, even on the first postoperative day. After the introduction of enteral feeding, the peak levels increased (Cmax, 655 ng/mL) and were achieved significantly sooner (Tmax, 2 hours). There was no significant difference in drug exposure between days 1, 3, and 5 (P > .05). The incidence of acute rejection was 25% and hypertension was reported in 4 of 12 patients during the first week. Neoral was well absorbed in the early post-liver transplantation period, provided effective immunosuppression, and was not associated with a high incidence of adverse events or toxicity. The introduction of enteral feeding improved absorption.