Prenatal treatment of ornithine transcarbamylase deficiency.

PURPOSE OF STUDY: Patients with neonatal urea cycle defects (UCDs) typically experience severe hyperammonemia during the first days of life, which results in serious neurological injury or death. Long-term prognosis despite optimal pharmacological and dietary therapy is still poor. The combination of intravenous sodium phenylacetate and sodium benzoate (Ammonul®) can eliminate nitrogen waste independent of the urea cycle. We report attempts to improve outcomes for males with severe ornithine transcarbamylase deficiency (OTCD), a severe X-linked condition, via prenatal intravenous administration of Ammonul and arginine to heterozygous carrier females of OTCD during labor. METHODS USED: Two heterozygote OTCD mothers carrying male fetuses with a prenatal diagnosis of OTCD received intravenous Ammonul, arginine and dextrose-containing fluids shortly before birth. Maintenance Ammonul and arginine infusions and high-caloric enteral nutrition were started immediately after birth. Ammonul metabolites were measured in umbilical cord blood and the blood of the newborn immediately after delivery. Serial ammonia and biochemical analyses were performed following delivery. SUMMARY OF RESULTS: Therapeutic concentrations of Ammonul metabolites were detected in umbilical cord and neonatal blood samples. Plasma ammonia and glutamine levels in the postnatal period were within the normal range. Peak ammonia levels in the first 24-48h were 53mcmol/l and 62mcmol/l respectively. The boys did not experience neurological sequelae secondary to hyperammonemia and received liver transplantation at ages 3months and 5months. The patients show normal development at ages 7 and 3years. CONCLUSION: Prenatal treatment of mothers who harbor severe OTCD mutations and carry affected male fetuses with intravenous Ammonul and arginine, followed by immediate institution of maintenance infusions after delivery, results in therapeutic levels of benzoate and phenylacetate in the newborn at delivery and, in conjunction with high-caloric enteral nutrition, prevents acute hyperammonemia and neurological decompensation. Following initial medical management, early liver transplantation may improve developmental outcome.

Mass cytometry reveals a distinct immunoprofile of operational tolerance in pediatric liver transplantation.

Long-term IS in transplant patients has significant morbidity, poorer quality of life, and substantial economic costs. TOL, defined as graft acceptance without functional impairment in the absence of IS, has been achieved in some pediatric LT recipients. Using mass cytometry, peripheral blood immunotyping was performed to characterize differences between tolerant patients and patients who are stable on single-agent IS. Single-cell mass cytometry was performed using blood samples from a single-center pediatric LT population of operationally tolerant patients to comprehensively characterize the immune cell populations in the tolerant state compared with patients on chronic low-dose IS. Specific T-cell populations of interest were confirmed by flow cytometry. This high-dimensional phenotypic analysis revealed distinct immunoprofiles between transplant populations as well as a CD4+ TOT (CD4+ CD5+ CD25+ CD38-/lo CD45RA) that correlates with tolerance in pediatric LT recipients. In TOL patients, the TOT was significantly increased as compared to patients stable on low levels of IS. This TOT cell was confirmed by flow cytometry and is distinct from classic Treg cells. These results demonstrate the power of mass cytometry to discover significant immune cell signatures that have diagnostic potential.

Treatment of recurrent posttransplant lymphoproliferative disorder of the central nervous system with high-dose methotrexate.

Posttransplant lymphoproliferative disorder (PTLD) is a frequent complication of intestinal transplantation and is associated with a poor prognosis. There is currently no consensus on optimal therapy. Recurrent PTLD involving the central nervous system (CNS) represents a particularly difficult therapeutic challenge. We report the successful treatment of CNS PTLD in a pediatric patient after liver/small bowel transplantation. Initial immunosuppression (IS) was with thymoglobulin, solucortef, tacrolimus, and mycophenolate mofetil. EBV viremia developed 8 weeks posttransplantation, and despite treatment with cytogam and valganciclovir the patient developed a polymorphic, CD20+, EBV+ PTLD with peripheral lymphadenopathy. Following treatment with rituximab, the lymphadenopathy resolved, but a new monomorphic CD20-, EBV+, lambda-restricted, plasmacytoid PTLD mesenteric mass emerged. Complete response of this PTLD was achieved with 6 cycles of cyclophosphamide, doxorubicin, vincristine, and prednisone (CHOP) chemotherapy; however, 4 months off therapy he developed CNS PTLD (monomorphic CD20-, EBV+, lambda-restricted, plasmacytoid PTLD) of the brain and spine. IS was discontinued and HD-MTX (2.5-5 gm/m(2)/dose) followed by intrathecal HD-MTX (2 mg/dose ×2-3 days Q 7-10 days per cycle) was administered Q 4-7 weeks. After 3 cycles of HD-MTX, the CSF was negative for malignant cells, MRI of head/spine showed near-complete response, and PET/CT was negative. The patient remains in complete remission now for 3.5 years after completion of systemic and intrathecal chemotherapy. Conclusion. HD-MTX is an effective therapy for CNS PTLD and recurrent PTLD that have failed rituximab and CHOP chemotherapy.

Successful treatment of recurrent primary sclerosing cholangitis after orthotopic liver transplantation with oral vancomycin.

Primary sclerosing cholangitis (PSC) is a progressive, cholestatic disease of the liver that is marked by inflammation of the bile ducts and damage to the hepatic biliary tree. Approximately 60-70% of patients also have inflammatory bowel disease and progression of PSC can lead to ulcerative colitis and cirrhosis of the liver. Due to limited understanding of the etiology and mechanism of PSC, the only existing treatment option is orthotopic liver transplantation (OLT); however, recurrence of PSC, after OLT is estimated to be between 5% and 35%. We discuss the successful treatment of a pediatric patient, with recurrent PSC, after OLT with oral Vancomycin.

Toll-like receptor 4 contributes to small intestine allograft rejection.

BACKGROUND: Although outcomes for small intestine transplantation (SIT) have improved in recent years, allograft rejection rates remain among the highest of solid organ grafts. The high load of commensal bacteria in the small intestine may contribute through activation of the toll-like receptor (TLR) pathway. In this study, we examine the participation of TLR4 in acute allograft rejection in an orthotopic mouse model of SIT. METHODS: Wild-type C57Bl/6 (H-2b) or TLR49(-/-) (H-2b) mice were transplanted with syngeneic (C57Bl/6), allogeneic (BALB/c; H-2d), or F1 (BALB/cxC57Bl/6; H-2d/b) vascularized, orthotopic small intestine grafts. Graft recipients were killed on days 2 to 6 posttransplant. Serum cytokines were measured by Luminex, and tissue was obtained for histology and quantitative real-time polymerase chain reaction. RESULTS: BALB/c grafts transplanted into C57Bl/6 recipients exhibited mixed inflammatory infiltrates, destruction of the mucosa, and significant apoptosis. TLR2 and TLR4 transcripts were modestly increased in syngeneic grafts on days 2 and 6 compared with native bowel, whereas TLR2 and TLR4 were significantly increased on days 2 and 6 in allogeneic grafts. Although fully mismatched and F1 grafts were rejected by C57Bl/6 recipients (mean survival time=8.2 and 9.3 days, respectively), graft survival was significantly prolonged in TLR4(-/-) recipients (mean survival time=10.6 and 14.3 days, respectively). Proinflammatory cytokines were markedly reduced in TLR4(-/-) graft recipients. CONCLUSIONS: Small intestine graft survival is prolonged in the absence of TLR4, suggesting that gut flora associated with the graft may augment alloimmune responses through TLR4. Thus, the TLR pathway may be a novel therapeutic target for improving SIT allograft survival.

Factors affecting survival to intestinal transplantation in the very young pediatric patient.

BACKGROUND: Very young pediatric patients awaiting intestinal transplantation have a high mortality rate due to long waiting times, scarcity of appropriate size donor organs, and mortality due to sepsis and liver failure. To investigate specific risk factors impacting survival to intestinal transplantation, we performed a 4-year institutional retrospective study comparing children who received grafts by age 18 months with children 18 months or younger who died while on the waiting list. PATIENTS AND METHODS: Twelve children comprised the transplanted group and had the underlying diagnoses: necrotizing enterocolitis, gastroschisis, Hirschsprung's disease, and omphalocele. Ten children comprised the deceased group and had the underlying diagnoses: intestinal atresia, necrotizing enterocolitis, gastroschisis, and midgut volvulus. Multiple risk factors were assessed in these groups. RESULTS: No differences in residual small bowel length, presence of the colon, number of line infections, or number of central lines were found. The average body weight of the transplanted group trended higher, whereas the deceased group had more impairment of hepatic function. Intestinal atresia was the most common diagnosis in the deceased group while none of the transplanted group carried this diagnosis. Ileocecal valve was retained in 80% of the deceased group and in none of the transplanted group. CONCLUSIONS: In children younger than 18 months, risk factors affecting survival to intestinal transplantation include small body size and advanced liver disease. A primary diagnosis of intestinal atresia and the presence of the ileocecal valve may confer additional risk to these very young children.

Outcomes of transplantation in children with primary hepatic malignancy.

HBL and HCC are the most common hepatic malignancies in children. The role of OLT in children with HCC is still a matter of debate. The aim of this study was to review our experience of OLT for HCC. Medical records of patients (<18 yr) who underwent OLT for HCC were reviewed and compared to children who underwent OLT for HBL and for indications other than malignancy. There were 25 patients: HCC (10 cases) and HBL (15 cases). The actuarial patient survival for HCC at one and five yr was 100% and 83.3%, for the HBL group the survival was 86.7% at both one and five yr, and for indications (n=377) other than malignancy the patient survival for pediatric OLT at our center was 87.7% and 84.7% at one and five yr, respectively. The actuarial recurrence free survival at five yr was 83.3% for HCC and 66.8% for HBL. In conclusion, OLT is a good therapeutic modality for children with HCC and HBL.

Risk factors for small bowel bacterial overgrowth in cystic fibrosis.

OBJECTIVES: The purpose of this study was to determine the prevalence of small bowel bacterial overgrowth in patients with pancreatic-insufficient cystic fibrosis (CF) compared with age-matched controls and to identify potential risk factors for small bowel bacterial overgrowth. PATIENTS AND METHODS: Fifty patients, 25 pancreatic-insufficient CF study patients (mean age, 17 y) and 25 gastrointestinal clinic control patients (mean age, 15 y), completed a glucose-hydrogen breath test after an overnight fast. Study patients completed a quality-of-life questionnaire modified from the Cystic Fibrosis Questionnaire. The medical history of each patient was compared with breath test results. A positive breath test was defined as a fasting hydrogen > or =15 ppm or a rise of > or =10 ppm hydrogen over baseline during the test. RESULTS: The prevalence of positive breath tests was higher in the CF study group (56%) than in the control group (20%) (P = 0.02). The mean fasting hydrogen levels of patients in the study and control groups were 22 and 5 ppm (P = 0.0001). The mean questionnaire scores were not significantly different between breath test-positive and -negative study patients. The use of azithromycin was associated with an increased risk of a positive breath test. Use of laxatives and inhaled ipratropium was associated with a decreased risk of a positive breath test. CONCLUSIONS: Patients with CF were more likely to have elevated fasting hydrogen levels compared with controls. This suggests a high prevalence of small bowel bacterial overgrowth in CF patients. Medications commonly used by CF patients may influence intestinal health.

Management of esophageal strictures in children with recessive dystrophic epidermolysis bullosa.

BACKGROUND: Recessive dystrophic epidermolysis bullosa is a rare, genetically transmitted skin disorder characterized by blister formation and scarring in response to minor trauma. One of the most debilitating features of the disease is the development of esophageal strictures, which produces profound dysphagia, exacerbating an already highly compromised nutritional status common to these patients. Due to the extreme fragility of epithelial surfaces, the optimal therapeutic approach to esophageal strictures in this setting has not been established. METHODS: We have developed an approach to treatment of esophageal strictures in children with epidermolysis bullosa combining upper endoscopy using small caliber endoscopes, endotracheal intubation, and fluoroscopically assisted balloon dilatation. We report our experience using this technique in 22 children who have undergone a total of 109 dilatations. RESULTS: Upper endoscopy, endotracheal intubation, and balloon dilatation were well tolerated by even very young children with epidermolysis bullosa. Dysphagia was markedly reduced post-procedure, permitting resumption of normal diet for age, including solids, within six hours of the procedure. Post-procedure recovery has been rapid and does not require admission to the hospital. Complications have been infrequent, minor, and limited to the first year of our experience. The mean interval between dilatations for all children is 11 months. All children have gained weight, and have not required steroids or phenytoin. CONCLUSIONS: Balloon dilatation is a safe and effective therapy for esophageal strictures in children with recessive dystrophic epidermolysis bullosa. Limited upper endoscopy and endotracheal intubation are well tolerated by these children. This approach should be considered as primary therapy in this clinical setting.