Elisabeth T. Tracy

Protocolized Approach to the Management of Congenital Diaphragmatic Hernia: Benefits of Reducing Variability in Care

PURPOSE Variable approaches to the care of infants with congenital diaphragmatic hernia (CDH) by multiple providers may contribute to inconsistent care. Our institution developed a comprehensive evidence-based protocol to standardize the management of CDH infants. This report reviews patient outcomes before and after the implementation of the protocol. METHODS Retrospective chart review of CDH infants managed with individualized care (preprotocol group, January 1997-December 2001, n = 22) or on the protocol (Protocol group, January 2002-July 2009, n = 47). Survival and other categorical variables were compared by chi(2) analysis, and continuous variables were compared using 1-sided analysis of variance analysis, with significance defined as P < .05. RESULTS Survival to discharge was significantly greater in the Protocol group (40/47; 85%) than the preprotocol group (12/22; 52%; P = .006), although mean gestational age, mean birth weight, and expected survival were not statistically different between the 2 groups. The use of supportive therapies, including high-frequency jet ventilation, inhaled nitric oxide, and extracorporeal life support, was similar between groups as well. CONCLUSIONS Since the implementation of a management protocol for infants with CDH, survival has improved significantly compared with expected survival and preprotocol controls. Reduction in the variability of care through use of an evidence-based protocol may improve the survival of CDH infants.

Partial splenectomy for hereditary spherocytosis: a multi-institutional review

BACKGROUND/PURPOSE Partial splenectomy has emerged as a surgical option for selected children with hereditary spherocytosis, with the goal of reducing anemia while preserving splenic function. This multi-institutional study is the largest series to date examining outcomes data for partial splenectomy in patients with hereditary spherocytosis. METHODS Data were collected retrospectively from 5 North American pediatric hospitals. Sixty-two children underwent partial splenectomy for hereditary spherocytosis between 1990 and 2008. RESULTS At 1 year following partial splenectomy, mean hemoglobin significantly increased by 3.0 ± 1.4 g/dL (n = 52), reticulocyte count decreased by 6.6% ± 6.6% (n = 41), and bilirubin level decreased by 1.3 ± 0.9 mg/dL (n = 25). Patients with poor or transient hematologic response were found to have significantly more splenic regeneration postoperatively compared with patients with a durable clinical response (maximal spleen dimension, 9.0 ± 3.4 vs 6.3 ± 2.2 cm). Clinically significant recurrence of anemia or abdominal pain led to completion splenectomy in 4.84% of patients. No patients developed postsplenectomy sepsis. CONCLUSIONS Our multi-institutional review indicates that partial splenectomy for hereditary spherocytosis leads to sustained and clinically significant improvement in hematologic profiles and clinical symptoms in most patients. Our data support partial splenectomy as an alternative for selected children with hereditary spherocytosis.

Bone Marrow Transplantation Augments the Effect of Brain- and Spinal Cord-Directed Adeno-Associated Virus 2/5 Gene Therapy by Altering Inflammation in the Murine Model of Globoid-Cell Leukodystrophy

Globoid-cell leukodystrophy (GLD) is an inherited demyelinating disease caused by the deficiency of the lysosomal enzyme galactosylceramidase (GALC). A previous study in the murine model of GLD (twitcher) demonstrated a dramatic synergy between CNS-directed adeno-associated virus 2/5 (AAV2/5) gene therapy and myeloreductive bone marrow transplantation (BMT). However, the mechanism by which these two disparate therapeutic approaches synergize is not clear. In addition, the therapeutic efficacy may have been limited since the CNS-directed gene therapy was restricted to the forebrain and thalamus. In the current study, intrathecal and intracerebellar injections were added to the therapeutic regimen and the mechanism of synergy between BMT and gene therapy was determined. Although AAV2/5 alone provided supraphysiological levels of GALC activity and reduced psychosine levels in both the brain and spinal cord, it significantly increased CNS inflammation. Bone marrow transplantation alone provided essentially no GALC activity to the CNS and did not reduce psychosine levels. When AAV2/5 is combined with BMT, there are sustained improvements in motor function and the median life span is increased to 123 d (range, 92–282 d) compared with 41 d in the untreated twitcher mice. Interestingly, addition of BMT virtually eliminates both the disease and AAV2/5-associated inflammatory response. These data suggest that the efficacy of AAV2/5-mediated gene therapy is limited by the associated inflammatory response and BMT synergizes with AAV2/5 by modulating inflammation.

Low volume is associated with worse patient outcomes for pediatric liver transplant centers.

BACKGROUND An inverse association between hospital procedure volume and postoperative mortality has been demonstrated for a variety of pediatric surgical procedures. The objective of our study was to determine whether such an association exists for pediatric liver transplantation. METHODS We performed a retrospective analysis of pediatric liver transplant procedures included in the Scientific Registry of Transplant Recipients over a 7.5-year time period from July 1, 2000, through December 31, 2007. Pediatric liver transplant centers were divided into three volume categories (high, middle, low) based on absolute annual volume. Mean 1-year patient survival rates and aggregate 1-year observed-to-expected (O:E) patient death ratios were calculated for each hospital volume category and then compared using ordered logistic regression and chi square analyses. RESULTS High-volume pediatric liver transplant centers achieved significantly lower aggregate 1-year O:E patient death ratios than low-volume centers. When freestanding childrens hospitals (FCH), childrens hospitals within adult hospitals (CAH), and other centers (OC) were considered separately, we found that a significant volume-outcomes association existed among OC centers but not among FCH or CAH centers. Low-volume OC centers, which represent 41.6% of all pediatric liver transplant centers and perform 10% of all pediatric liver transplantation, had the least favorable aggregate 1-year O:E patient death ratio of all groups. CONCLUSIONS We demonstrate that a significant center volume-outcomes relationship exists among OC pediatric liver transplant centers but not among FCH or CAH centers. These findings support the possible institution of minimum annual procedure volume requirements for OC pediatric liver transplant centers.

Isolation and expansion of oligodendrocyte progenitor cells from cryopreserved human umbilical cord blood

BACKGROUND AIMS Oligodendrocyte precursor cells (OPC) hold promise as a cellular therapy for demyelinating diseases. The feasibility of using OPC-based therapies in humans depends upon a reliable, readily available source. We have previously described the isolation, expansion and characterization of oligodendrocyte-like cells from fresh human umbilical cord blood (UCB). We now describe the isolation and expansion of OPC from thawed, cryopreserved UCB. METHODS We thawed cryopreserved UCB units employing a standard clinical protocol, then isolated and plated mononuclear cells under previously established culture conditions. All OPC cultures were trypsinized at 21 days, counted, then characterized by flow cytometry after fixation, permeablization and labeling with the following antibodies: anti-oligodendrocyte marker 4 (O4), anti-oligodendrocyte marker 1 (O1) and anti-myelin basic protein (MBP). OPC were also placed in co-culture with shiverer mouse neuronal cells then stained in situ for beta tubulin III (BT3) and MBP as a functional assay of myelination. RESULTS The average OPC yield per cryopreserved UCB unit was 64% of that seen with fresh UCB. On flow cytometric analysis, 74% of thawed UCB units yielded cells with an O4-expression level of at least 20% of total events, compared with 95% of fresh UCB units. We observed myelination of shiverer neurons in our functional assay, which could be used as a potency assay for release of OPC cells in phase I human clinical trials. CONCLUSIONS Our results demonstrate that OPC can be derived reliably from thawed, cryopreserved UCB units, and support the feasibility of using these cells in human clinical trials.

Isolation of oligodendrocyte-like cells from human umbilical cord blood.

BACKGROUND As human umbilical cord blood (UCB) is known to be a rich source of progenitor cells, the prospect of isolating a subset of these cells that could differentiate into cells of non-hematopoietic lineages suggests a therapeutic use for patients with inherited lysosomal and peroxisomal storage diseases currently treated with UCB transplantation. METHODS Oligodendrocyte-like cells were isolated from UCB by density-gradient centrifugation and expanded using selective media. We then characterized this population of cells using standard immunohistochemical staining methods for neural cell proteins and polymerase chain reaction (PCR) to detect RNA sequences for myelin basic protein (MBP). We also developed a functional assay demonstrating myelination of neurons in vitro. RESULTS Cells with oligodendrocyte-like morphology were reproducibly cultured ex vivo from fresh human UCB. Cells stained positively for multiple oligodendria cell markers (O1, MBP and CNPase) via immunohistochemical staining and flow cytometry. PCR confirmed the presence of MBP and CNPase mRNA. A further in vitro functional assay demonstrated the myelination of mature neuronal cells from the brain of a myelin-deficient murine model co-cultured with the oligodendrocyte-like cells. DISCUSSION After human UCB transplant, donor-derived cells have been noted to migrate to the brain over time. Although is not known whether these cells solely deliver enzyme replacement or a subset engrafts and differentiates into mature neural cells, the clinical improvements noted in these patients suggest a potential role for targeted cellular therapy. Oligodendrocyte-like cells isolated ex vivo and expanded from human UCB could provide a potential cellular therapy for patients with demyelinating or dismyelinating diseases.

Partial splenectomy for hereditary spherocytosis.

The significant risks associated with total splenectomy have led to interest in the use of partial splenectomy as an alternative surgical therapy for children who have congenital hemolytic anemia. Partial splenectomy is designed to remove enough spleen to gain desired hematologic outcomes while preserving splenic immune function. Although preliminary data demonstrate successful laboratory and clinical outcomes after partial splenectomy in various congenital hemolytic anemias, conclusive data comparing the efficacy of partial splenectomy to total splenectomy are not reported. Based on preliminary data, a definitive clinical trial of partial splenectomy in children who have severe congenital hemolytic anemia may be warranted.

Pediatric injury patterns by year of age

PURPOSE Since trauma is the leading cause of death and disability among children, understanding injury patterns may reduce morbidity and mortality through targeted prevention efforts. The purpose of this study was to identify pediatric injury patterns by year of age using a large national database. METHODS We searched the National Trauma Database (NTDB) Research Data Set 7.0 for patients aged 0-18 years with the following relevant ICD-9 external-cause-of-injury codes (e-codes). We also reviewed our institutional trauma registry data (1999-2009). Data were analyzed using χ(2) analysis and ANOVA with significance defined as p<0.05. RESULTS We identified 354,196 pediatric trauma patients. The leading MOI were motor-vehicle collisions (MVC) for ages 10-18 years and falls for ages 0-9 years. Fire was the second leading MOI among 1-year-olds, but not a major MOI in other age groups. Penetrating trauma was the MOI for 21% of injuries among adolescents with public or no insurance (versus 7.5% adolescents with private insurance). Injury severity scores were highest for children <1 year old and children 14-18 years old. Our review of 1209 patients from our institution yielded additional detail. CONCLUSION MVC and falls remain leading pediatric MOI. In our year-of-age analysis, we found several interesting trends, including a higher-than-expected rate of penetrating trauma. Our findings may support targeted injury prevention efforts.

Preliminary Observations of the Use of High-Frequency Jet Ventilation as Rescue Therapy in Infants with Congenital Diaphragmatic Hernia

BACKGROUND/PURPOSE Congenital diaphragmatic hernia (CDH) is associated with mortality of 10% to 50%. Several investigators have reported outcomes from centers using high-frequency oscillatory ventilation in their management of CDH, but there are no recent reports on use of high-frequency jet ventilation. METHODS During the study period from January 2001 until August 2007, infants with CDH who were cared for at Duke University Medical Center received high-frequency jet ventilation as a rescue mode of high-frequency ventilation. We compared actual survival with predicted survival for infants treated only with conventional ventilation vs those rescued with high-frequency jet ventilation after failing conventional ventilation. RESULTS Survival for the 16 infants that received high-frequency jet ventilation was predicted to be 63%; actual survival was 75%. Survival for the 15 infants that received only conventional ventilation was predicted to be 83%; actual survival was 87%. We observed no significant survival benefit for high-frequency jet ventilation, 8.0% (95 confidence interval, -22.0% to 38.1%; P = .59). CONCLUSIONS Although our sample size was small, we conclude with consideration of the absolute results, the degree of illness of the infants, and the biologic plausibility for the intervention that high-frequency jet ventilation is an acceptable rescue ventilation mode for infants with CDH.

Factors associated with survival in pediatric adrenocortical carcinoma: An analysis of the National Cancer Data Base (NCDB)

PURPOSE Adrenocortical carcinoma (ACC) is a rare tumor in children with important distinctions from the adult disease. We reviewed the National Cancer Data Base (NCDB) to determine factors associated with long-term survival. METHODS The NCDB was queried for patients less than 18 years of age who were diagnosed with ACC between 1998 and 2011. Kaplan-Meier analysis was utilized to determine factors significantly associated with overall survival. RESULTS A total of 111 patients were included (median age: 4 years, 69% female). ACC was more common in the youngest cohort, with 48% of cases occurring in children younger than the age of 3. Median tumor size was 9.5 cm (IQR: 6.5-13.0), and 87% of patients underwent some form of surgical resection. Among children with available data, 19 of 62 presented with metastases. Overall 1- and 3-year survival was 70% and 64%, respectively. Age, tumor size, extension of tumor into surrounding tissue, and metastatic disease were all found to be significantly associated with survival. Among patients who underwent a surgical procedure, margin status was also found to be significantly associated with survival. CONCLUSION Age, tumor size, extension of tumor, metastatic disease, and margin status are significantly associated with long-term survival in children with adrenocortical carcinoma.