Rare and de novo variants in 827 congenital diaphragmatic hernia probands implicate LONP1 as candidate risk gene.

Congenital diaphragmatic hernia (CDH) is a severe congenital anomaly that is often accompanied by other anomalies. Although the role of genetics in the pathogenesis of CDH has been established, only a small number of disease-associated genes have been identified. To further investigate the genetics of CDH, we analyzed de novo coding variants in 827 proband-parent trios and confirmed an overall significant enrichment of damaging de novo variants, especially in constrained genes. We identified LONP1 (lon peptidase 1, mitochondrial) and ALYREF (Aly/REF export factor) as candidate CDH-associated genes on the basis of de novo variants at a false discovery rate below 0.05. We also performed ultra-rare variant association analyses in 748 affected individuals and 11,220 ancestry-matched population control individuals and identified LONP1 as a risk gene contributing to CDH through both de novo and ultra-rare inherited largely heterozygous variants clustered in the core of the domains and segregating with CDH in affected familial individuals. Approximately 3% of our CDH cohort who are heterozygous with ultra-rare predicted damaging variants in LONP1 have a range of clinical phenotypes, including other anomalies in some individuals and higher mortality and requirement for extracorporeal membrane oxygenation. Mice with lung epithelium-specific deletion of Lonp1 die immediately after birth, most likely because of the observed severe reduction of lung growth, a known contributor to the high mortality in humans. Our findings of both de novo and inherited rare variants in the same gene may have implications in the design and analysis for other genetic studies of congenital anomalies.

Comparative outcomes of right versus left congenital diaphragmatic hernia: A multicenter analysis.

BACKGROUND: Congenital diaphragmatic hernia (CDH) occurs in 1 out of 2500-3000 live births. Right-sided CDHs (R-CDHs) comprise 25% of all CDH cases, and data are conflicting on outcomes of these patients. The aim of our study was to compare outcomes in patients with right versus left CDH (L-CDH). METHODS: We analyzed a multicenter prospectively enrolled database to compare baseline characteristics and outcomes of neonates enrolled from January 2005 to January 2019 with R-CDH vs. L-CDH. RESULTS: A total of 588, 495 L-CDH, and 93 R-CDH patients with CDH were analyzed. L-CDHs were more frequently diagnosed prenatally (p=0.011). Lung-to-head ratio was similar in both cohorts. R-CDHs had a lower frequency of primary repair (p=0.022) and a higher frequency of need for oxygen at discharge (p=0.013). However, in a multivariate analysis, need for oxygen at discharge was no longer significantly different. There were no differences in long-term neurodevelopmental outcomes assessed at two year follow up. There was no difference in mortality, need for ECMO, pulmonary hypertension, or hernia recurrence. CONCLUSION: In this large series comparing R to L-CDH patients, we found no significant difference in mortality, use of ECMO, or pulmonary complications. Our study supports prior studies that R-CDHs are relatively larger and more often require a patch or muscle flap for repair. TYPE OF STUDY: Prognosis study LEVEL OF EVIDENCE: Level II.

The association between congenital diaphragmatic hernia and undescended testes.

BACKGROUND: Undescended testes (UDT) is a common abnormality treated by pediatric surgeons. Embryological development of the genitourinary ridge is in close proximity with the pleuroperitoneal fold. The purpose of this paper is to describe the association between congenital diaphragmatic hernia (CDH) and UDT. MATERIALS/METHODS: As part of the DHREAMS (Diaphragmatic Hernia Research and Exploration: Advancing Molecular Science) study (www.cdhgenetics.com), all living children had tissue banked and analyzed for common genetic mutations and had a health assessment performed by telephone consultation with the parents at two years of age. The incidence of UDT was then compared to clinical and genetic findings previously identified. RESULTS: Sixty-five males had complete information from their 2year health assessment. Of these, twelve (18%) had a UDT repaired by the time of the 2year assessment. Of the twelve who had a repair, no child had a unilateral UDT which was contralateral to the side of the CDH. There were no differences in rate or number of mutations of any of the genes we checked as part of our study. CONCLUSION: It appears that a deficiency of diaphragm tissue may affect the first or transabdominal phase of the testicular descent, leading to an increased incidence of UDT.

First 24-h SNAP-II score and highest PaCO2 predict the need for ECMO in congenital diaphragmatic hernia.

BACKGROUND/PURPOSE: Early clinical predictors for the use of ECMO in patients with congenital diaphragmatic hernia (CDH) are lacking. We sought to evaluate the first 24-h SNAP-II score and highest PaCO2 as predictors of ECMO support and in-hospital mortality in neonates with CDH. METHODS: Retrospective review of 47 consecutive neonates with CDH admitted to our institution from January 2007 to December 2010 was performed. Covariates of ECMO use including SNAP-II score and highest PaCO2 within the first 24 h of NICU admission were evaluated. RESULTS: Of the 47 infants in this study, 24 patients were supported with ECMO. The ECMO group had a higher incidence of pulmonary hypertension, higher PaCO2, and higher 24-h SNAP-II scores. Only the SNAP-II score and not highest PaCO2 predicted mortality following multivariate adjustment. CONCLUSIONS: The first 24-h SNAP-II score and highest PaCO2 may provide some prognostic value in identifying neonates who undergo ECMO support; however neither measure was independently associated with the use of therapy. Only the SNAP-II score was associated with in-hospital mortality following multivariate adjustment. Additional study is needed to validate these results in a larger data set.

Developmental outcomes of children with congenital diaphragmatic hernia: a multicenter prospective study.

PURPOSE: To determine developmental outcomes and associated factors in patients with congenital diaphragmatic hernia (CDH) at 2 years of age. METHODS: This is a multicenter prospective study of a CDH birth cohort. Clinical and socioeconomic data were collected. Bayley Scales of Infant Development (BSID-III) and Vineland Adaptive Behavior Scales (VABS-II) were performed at 2 years of age. RESULTS: BSID-III and VABS-II assessments were completed on 48 and 49 children, respectively. The BSID-III mean cognitive, language, and motor scores were significantly below the norm mean with average scores of 93 ± 15, 95 ± 16, and 95 ± 11. Ten percent (5/47) scored more than 2 standard deviations below the norm on one or more domains. VABS-II scores were similar to BSID-III scores with mean communication, daily living skills, social, motor, adaptive behavior scores of 97 ± 14, 94 ± 16, 93 ± 13, 97 ± 10, and 94 ± 14. For the BSID-III, supplemental oxygen at 28 days, a prenatal diagnosis, need for extracorporeal membrane oxygenation (ECMO) and exclusive tube feeds at time of discharge were associated with lower scores. At 2 years of age, history of hospital readmission and need for tube feeds were associated with lower scores. Lower socioeconomic status correlated with lower developmental scores when adjusted for significant health factors. CONCLUSION: CDH patients on average have lower developmental scores at 2 years of age compared to the norm. A need for ECMO, oxygen at 28 days of life, ongoing health issues and lower socioeconomic status are factors associated with developmental delays.

Defective pulmonary innervation and autonomic imbalance in congenital diaphragmatic hernia.

Congenital diaphragmatic hernia (CDH) is associated with significant mortality due to lung hypoplasia and pulmonary hypertension. The role of embryonic pulmonary innervation in normal lung development and lung maldevelopment in CDH has not been defined. We hypothesize that developmental defects of intrapulmonary innervation, in particular autonomic innervation, occur in CDH. This abnormal embryonic pulmonary innervation may contribute to lung developmental defects and postnatal physiological derangement in CDH. To define patterns of pulmonary innervation in CDH, human CDH and control lung autopsy specimens were stained with the pan-neural marker S-100. To further characterize patterns of overall and autonomic pulmonary innervation during lung development in CDH, the murine nitrofen model of CDH was utilized. Immunostaining for protein gene product 9.5 (a pan-neuronal marker), tyrosine hydroxylase (a sympathetic marker), vesicular acetylcholine transporter (a parasympathetic marker), or VIP (a parasympathetic marker) was performed on lung whole mounts and analyzed via confocal microscopy and three-dimensional reconstruction. Peribronchial and perivascular neuronal staining pattern is less complex in human CDH than control lung. In mice, protein gene product 9.5 staining reveals less complex neuronal branching and decreased neural tissue in nitrofen-treated lungs from embryonic day 12.5 to 16.5 compared with controls. Furthermore, nitrofen-treated embryonic lungs exhibited altered autonomic innervation, with a relative increase in sympathetic nerve staining and a decrease in parasympathetic nerve staining compared with controls. These results suggest a primary defect in pulmonary neural developmental in CDH, resulting in less complex neural innervation and autonomic imbalance. Defective embryonic pulmonary innervation may contribute to lung developmental defects and postnatal physiological derangement in CDH.

Feasibility of laparoscopic Nissen fundoplication after pediatric lung or heart-lung transplantation: should this be the standard?

BACKGROUND: Five-year graft survival in the pediatric lung transplant (LTxp) population is less than 50%, with obliterative bronchiolitis (OB) the leading cause of death at 1, 3, and 5 years post-transplant. Bronchiolitis obliterans syndrome (BOS), defined using spirometry values, is the clinical surrogate for the histological diagnosis of obliterative bronchiolitis. Surgical correction of documented gastroesophageal reflux disease (GERD) has been proposed as a means to potentially delay the onset of BOS and prolong allograft survival in adults before or after lung transplantation but only one such study exists in children. We have examined the safety and possible benefits of laparoscopic antireflux surgery in pediatric patients following lung (LTxp) and heart-lung transplantation (HLTxp). METHODS: An Institutional Review Board (IRB)-approved retrospective chart review was performed to evaluate the outcomes and complications of laparoscopic antireflux surgery in pediatric lung and heart-lung transplant patients. Spirometry data were collected for BOS staging using BOS criteria for children. RESULTS: Twenty-five lung and heart-lung transplants were performed between January 2003 and July 2009. Eleven transplant recipients, including six double-lung and five heart-lung (HLTxp), with a median age of 11.7 years (range 5.1-18.4 years), underwent a total of 12 laparoscopic Nissen fundoplications at a median of 427 days after transplant (range 51-2310 days). GERD was determined based upon clinical impression, pH probe study, gastric emptying study, and/or esophagram in all patients. Three patients already had a gastrostomy tube in place and two had one placed at the time of fundoplication. There were no conversions to open surgery, 30-day readmissions, or 30-day mortalities. Complications included one exploratory laparoscopy for free air 6 days after laparoscopic Nissen fundoplication for a gastric perforation that had spontaneously sealed. Another patient required a revision laparoscopic Nissen 822 days following the initial fundoplication for a paraesophageal hernia and recurrent GERD. The average length of hospital stay was 4.4 ± 1.7 days. Nine of the 12 fundoplications were performed in patients with baseline spirometry values prior to fundoplication and who could also complete spirometry reliably. One of these nine operations was associated with improvement in BOS stage 6 months after fundoplication; seven were associated with no change in BOS stage; and one was associated with a decline in BOS stage. CONCLUSION: It is feasible to perform laparoscopic Nissen fundoplication in pediatric lung and heart-lung transplant recipients without mortality or significant morbidity for the treatment of GERD. The real effect on pulmonary function cannot be assessed due to our small sample size and lack of reproducible spirometry in our younger patients. Additional studies are needed to elucidate the relationship between antireflux surgery and the potential for improving pulmonary allograft function and survival in children which has been previously observed in adult patients.

Minimally invasive congenital diaphragmatic hernia repair: a 7-year review of one institution's experience.

BACKGROUND: Minimally invasive surgery (MIS) has been described for the repair of congenital diaphragmatic hernias (CDH) in neonates, infants, and children. This report evaluates patient selection, operative technique, and clinical outcomes for MIS repair of CDHs from a single center's experience. METHODS: All cases of CDH at a tertiary care pediatric hospital with an initial attempt at MIS repair from January 2001 to December 2007 were reviewed. RESULTS: A total of 22 children underwent an initial attempt at MIS repair of their CDH (5 Morgagni and 17 Bochdalek hernias). The children ranged in age from 1 day to 6 years (mean, 13.9 +/- 23 months) and weighed 2.2 to 21 kg (mean, 7.4 +/- 5.50 kg) at the time of the operation. All five Morgagni hernias were managed successfully with laparoscopic primary repair. Six of the Bochdalek hernias were found in infants and children (age range, 6-71 months). All these were managed successfully with primary repair by an MIS approach (2 by laparoscopy and 4 by thoracoscopy). The remaining 11 Bochdalek hernias were found in neonates (age range, 1 day to 8 weeks). Four of the Bochdalek hernias were right-sided. Nine of the Bochdalek hernias in neonates were repaired thoracoscopically. One neonate required conversion to laparotomy, and another underwent conversion to thoracotomy. Four of the neonates with Bochdalek hernias required a prosthetic patch. Two of the neonates also had significant associated congenital cardiac defects. Overall, there were two recurrences involving one 3-day-old who underwent a primary thoracoscopic repair and another 3-day-old who underwent a thoracoscopic patch repair. The follow-up period ranged from 5 months to 5 years. CONCLUSIONS: Morgagni hernias can be managed successfully by laparoscopy, whereas thoracoscopy is preferred for neonatal Bochdalek hernias. Either approach can be successful for infants and children with Bochdalek hernias. Additionally, patients with congenital cardiac defects and those requiring prosthetic patches can undergo a MIS CDH repair with a successful outcome.

Thoracoscopic aortopexy for vascular compression of the trachea: approach from the right.

Tracheomalacia resulting from vascular compression of the trachea may require aortopexy for symptomatic relief. Several operative approaches have been described for infants and children. The authors describe the technique of aortopexy by means of a right-sided thoracoscopic method as the initial approach to relieve tracheal compression in 2 children. Intraoperative bronchoscopy is mandatory to assess the adequacy of aortopexy prior to the completion of suture placement. This procedure was very successful in relieving tracheal compression in a 17-month-old boy with an aberrant innominate artery take-off and in a 2-year and 7-month-old boy with a history of esophageal atresia/tracheoesophageal fistula repair and severe tracheomalacia. A right-sided thoracoscopic approach to aortopexy in infants with severe tracheomalacia may be successfully performed as the initial operative intervention in infants with vascular compression of the trachea.

Triple fistula: management of a double tracheoesophageal fistula with a third H-type proximal fistula.

Esophageal atresia (EA) with or without tracheoesophageal fistula (TEF) is a relatively common congenital condition in which there have been several described anatomical variants. The most common type, EA with distal TEF, comprises more than 75% of cases in many reports. Less commonly, a smaller proximal pouch fistula (H-type) will be associated with this most common variant in 1.4% of these cases. Only 2% of all cases of EA/TEF will have 2 large fistulas between the trachea and esophagus in which the end of the upper esophageal pouch connects terminally to the midtrachea and the distal esophagus arises from the trachea near the carina. Here we describe the management of an infant with this type of EA/TEF who was also found to have an H-type TEF of the proximal trachea. The combination of this type of EA/TEF with an associated H-type TEF or "triple fistula" has been previously described in the literature in only 1 other patient.

Laparoscopic versus open Nissen fundoplication in infants after neonatal laparotomy.

BACKGROUND: Nissen fundoplication is an effective treatment of gastroesophageal reflux in infants. Laparoscopic procedures after previous laparotomy are technically more challenging. The role of laparoscopic Nissen fundoplication after neonatal laparotomy for diseases unrelated to reflux is poorly described. METHODS: This was a retrospective review of open vs laparoscopic Nissen fundoplication in infants after neonatal laparotomy. Of 32 infants who underwent neonatal laparotomy, 26 required a surgical antireflux operation within the first year of life. Twelve infants underwent laparoscopic Nissen fundoplication versus 14 infants who underwent open Nissen fundoplication. Parameters like age, weight, operative time, number of previous operations, length of stay following fundoplication, time to feedings, and complications were compared between the 2 groups. RESULTS: No statistically significant differences existed between most of the parameters compared following laparoscopic vs open Nissen fundoplication. No conversions to open procedures were necessary in infants undergoing laparoscopic fundoplication, and these infants resumed enteral feeds earlier than those who underwent the open procedure. CONCLUSION: Laparoscopic compared with open Nissen fundoplication performed in infants after a neonatal laparotomy were comparable procedures across most data points studied. However, a laparoscopic fundoplication did allow for earlier return to enteral feeds compared with the open approach. Laparoscopic Nissen fundoplication is technically feasible, safe, and effective in the treatment of gastroesophageal reflux in infants with a previous neonatal laparotomy.

Mechanisms of nitric oxide-mediated intestinal barrier failure in necrotizing enterocolitis.

Necrotizing enterocolitis (NEC) is the leading intestinal emergency in premature infants. The underlying etiology of NEC remains elusive, but hypoxic conditions and early enteral feeding are consistently implicated as the main risk factors in the pathogenesis of NEC. We postulate that nitric oxide (NO) plays a key role as a molecular signaling "hub" in the generation of gut barrier failure in NEC. Clinical studies suggest that inflammatory cytokines and excessive NO production may contribute to the pathogenesis of NEC. One of the major challenges in defining the critical signaling pathways that lead to the development of NEC is the lack of specific biochemical markers that consistently delineate the early stages of NEC. Intestinal pathology and molecular markers derived from late-stage NEC represent end-stage findings and thus provide little insight into the early events that led to intestinal inflammation. Such markers may not represent viable therapeutic targets for the treatment or prevention of NEC. Therefore, novel strategies are needed to identify the patients at risk for NEC and define the clinically relevant molecules that characterize the early stages of NEC. This review will examine the mechanisms of NO-mediated gut barrier failure and propose novel genetic-based approaches for elucidating the critical molecular pathways in NEC.

The high morbidity associated with handlebar injuries in children.

BACKGROUND: Although injury prevention strategies for bicyclists have focused on legislation requiring helmet use to prevent head trauma, direct impact handlebar injuries account for a significant proportion of bicycle-related injuries. Little attention, however, has been paid to strategies that prevent direct impact handlebar injuries. We reviewed our experience with bicycle-related injuries and compared outcome for children who flipped over the handlebars to those for children who sustained direct impact from the handlebars. METHODS: We queried our prospective trauma database for all bicycle injuries from 1998 to 2003. All patients with the descriptor "handlebar" in the subtext were selected. Patients were divided into two groups: those who flipped over the handlebars (n = 160) and those who sustained direct impact from the handlebars (n = 61). We examined age, gender, helmet use, injury severity score (ISS), Glasgow Coma Score (GCS), length of stay (LOS) and the need for operation. The Student's t test was used to compare continuous variables when the data were normally distributed and the Mann-Whitney was used when the data were skewed. Chi-square analysis or Fisher's exact test was used to compare categorical data. RESULTS: There was no difference between the two groups with respect to age, gender, helmet use, ISS, and GCS. However, children who suffered from handlebar injuries were more likely to require operative intervention (19/61 versus 28/160, p = 0.04) and had a significantly longer LOS (3 days versus 1 day, p < 0.001). Children who sustained direct impact from the handlebars and required operative intervention were statistically more likely to suffer from abdominal or soft tissue injuries, while those who flipped over the handlebars were statistically more likely to suffer from facial or skeletal injuries. CONCLUSIONS: Children who suffer from direct impact of the handlebars are more likely to require operative intervention and have a longer LOS than those who flip over the handlebars. While helmet utilization by bicyclists may have reduced the number of serious head injuries, direct impact from the handlebars remains a major source of bicycle-related morbidity since nearly one third of these patients required surgery. Future injury prevention strategies for bicyclists should be aimed at reducing the incidence of direct impact handlebar-related injuries.

Peroxynitrite inhibits enterocyte proliferation and modulates Src kinase activity in vitro.

Overproduction of nitric oxide (NO) or its toxic metabolite, peroxynitrite (ONOO-), after endotoxemia promotes gut barrier failure, in part, by inducing enterocyte apoptosis. We hypothesized that ONOO- may also inhibit enterocyte proliferation by disrupting the Src tyrosine kinase signaling pathway, thereby blunting repair of the damaged mucosa. We examined the effect of ONOO- on enterocyte proliferation and Src kinase activity. Sprague-Dawley rats were challenged with LPS or saline, whereas intestinal epithelial cell line cells were treated with ONOO- or decomposed ONOO- in vitro. Enterocyte proliferation in vivo and in vitro was measured by 5-bromo-2'-deoxyuridine (BrdU) or [3H]thymidine incorporation. Src kinase activity in cell lysates was determined at various times. LPS challenge in vivo and ONOO- treatment in vitro inhibited enterocyte proliferation. ONOO- treatment blunted the activity of Src and its downstream target, focal adhesion kinase, in a time-dependent manner. ONOO- blocked mitogen (FBS, EGF)-induced enterocyte proliferation and Src phosphorylation while increasing Src nitration. Thus ONOO- may promote gut barrier failure not only by inducing enterocyte apoptosis but also by disrupting signaling pathways involved in enterocyte proliferation.

Mechanism of intestinal-derived fungal sepsis by gliotoxin, a fungal metabolite.

BACKGROUND/PURPOSE: Gut barrier dysfunction resulting from fungal overgrowth may be caused by the interaction of gliotoxin (GT), a fungal metabolite, with enterocytes. The goal of this study was to determine the mechanisms by which gliotoxin (GT), a fungal metabolite, causes enterocyte apoptosis. METHODS: The authors measured enterocyte apoptosis, caspase-3 activity, pro-caspase-3, and poly (ADP-ribose) polymerase (PARP) cleavage in GT-exposed IEC-6 cells, a rat intestinal cell line. RESULTS: GT induced apoptosis in IEC-6 cells. The pan-caspase inhibitor ZVAD suppressed this GT-mediated apoptosis. GT induced a 15-fold increase in caspase-3 activity over media control. The authors detected PARP cleavage by after GT exposure. DTT pretreatment decreased apoptosis compared with GT alone. CONCLUSIONS: This study supports the concept that fungal overgrowth may lead to gut barrier dysfunction by the local release of gliotoxin and the induction enterocyte apoptosis.

Development of a novel method to predict disability after head trauma in children.

BACKGROUND/PURPOSE: Although analysis of functional independence measures (FIM) at discharge are useful for assessing extent of disability in head-injured children, there is no reliable method to predict the severity of disability at the time of admission. The authors developed a novel method to predict severe disability after head trauma on admission. METHODS: Head-injured patients, 2 to 16 years old, with FIM recorded at discharge (n = 3,491) were identified in our state trauma database for the period from 1993 through 1996. Patients categorized as completely dependent by one or more of the FIM (Feeding, Locomotion, Expression, Transfer Mobility, Social Interaction) were classified as disabled. Probability of disability (P(D)) was estimated based on regression weights for Glasgow Coma Scale (GCS), Injury Severity Score (ISS), age, and number of anatomic regions injured. Observed to expected disability rates were compared using a test data set of 2,553 patients entered in the database between 1997 through 1999. RESULTS: There was no statistically significant difference between observed and expected disability across all P(D) intervals, which suggests that the P(D) accurately predicted disability. CONCLUSIONS: P(D) offers a novel and reliable method for early prediction of likelihood of disability in children who sustain head trauma. Routine use of the P(D) may lead to earlier intervention to improve long-term results in head-injured children.

NF-kappaB inhibition enhances peroxynitrite-induced enterocyte apoptosis.

BACKGROUND: Sustained overproduction of nitric oxide and peroxynitrite (ONOO(-)) in conditions such as necrotizing enterocolitis and inflammatory bowel disease may promote gut barrier failure by inducing enterocyte apoptosis. NF-kappaB is upregulated in the gut during inflammation and, in addition to its proinflammatory effects, may upregulate protective or antiapoptotic factors such as inhibitor of apoptosis proteins (IAPs). We have previously demonstrated that NF-kappaB inhibition increases cytokine-induced enterocyte apoptosis; however, the effect of NF-kappaB on ONOO(-)-induced enterocyte apoptosis is unknown. MATERIALS AND METHODS: Rat intestinal epithelial cells (IEC-6) were transfected with the adenoviral vector AdIkappaB or AdlacZ. AdIkappaB contains a mutated form of IkappaB which functions as a superrepressor of NF-kappaB. Cells were then treated with 50 microM ONOO(-) or decomposed ONOO(-). Apoptosis was then determined by flow cytometry with annexin V-FITC and propidium iodide staining. Caspase activation and IAP, Bcl-2, Bad, and Bax expression were examined using Western blot analysis, and NF-kappaB activation was determined via electrophoretic mobility shift assay (EMSA). RESULTS: Inhibition of NF-kappaB with AdIkappaB significantly enhanced ONOO(-)-induced apoptosis in IEC-6 cells. ONOO(-) treatment did not activate NF-kappaB in IEC-6 cells as determined by EMSA. There was no difference in IAP, Bcl-2, Bad, and Bax expression between nontransfected, AdlacZ-transfected, and AdIkappaB-transfected cells. Baseline procaspase 3 activation was increased in AdIkappaB-transfected cells. CONCLUSIONS: NF-kappaB inhibition enhances ONOO(-)-induced enterocyte apoptosis, suggesting that NF-kappaB upregulates a protective factor. This protective factor does not appear to be an IAP or Bcl-2 family member and may be expressed constitutively, since ONOO(-) did not activate NF-kappaB over baseline levels of activation.

Role of nitric oxide and peroxynitrite in gut barrier failure.

Bacterial translocation (BT) may be a normal physiologic process that is important for mucosal antigen sampling in the gut. However, physiologic insults such as endotoxemia, hemorrhagic shock, or necrotizing enterocolitis (NEC) may lead to pathologic BT and thus contribute to the pathogenesis of nosocomial infection. The mechanism may involve accelerated enterocyte apoptosis at the intestinal villus apex resulting, at least transiently, in a "bare area" at the villus tip where bacteria can attach and traverse the epithelium. Evidence suggests that sustained upregulation of the inducible isoform of nitric oxide synthase (NOS-2) co-localizes with enterocyte apoptosis and immunoreactivity to 3-nitrotyrosine, the footprint of peroxynitrite (ONOO-), a potent oxidant formed by the reaction of nitric oxide (NO) with superoxide. We propose that the bare area at the villus apex is caused by apoptosis of enterocytes that have migrated from the base of the crypts to the villus apex and are shed into the intestinal lumen. These bare areas, and thus the degree of BT, may be the result of an imbalance between enterocyte proliferation and apoptosis. We postulate that normal enterocyte apoptosis is mediated by the caspase cascade, whereas enterocyte proliferation and differentiation in the crypt may be regulated by tyrosine kinase-dependent signaling pathways. Both of these cellular pathways may be influenced by overproduction of NO and its metabolite ONOO-. Therefore, sustained NO production and ONOO- formation occurring in inflammatory states may differentially accelerate apoptosis in the villus apex and/or inhibit proliferation at the base of the crypts resulting in expanded extrusion zones at the villus tip and accelerated BT.

Risk factors for splenectomy in children with blunt splenic trauma.

BACKGROUND/PURPOSE: Nonoperative management and splenic preservation have become standards of care for management of pediatric blunt splenic trauma. However, review of the Pennsylvania Trauma Outcome Study (PTOS) registry found that 15% of children with blunt splenic injury still underwent splenectomy. The authors sought to determine the factors that predisposed to splenectomy in this population. METHODS: Between 1993 and 1997, 754 children, ages 0 to 16 years, who sustained blunt splenic trauma were entered in the PTOS database. These patients were stratified into groups according to the mode of management: nonoperative, splenorrhaphy, or splenectomy. Logistic regression was performed to determine factors associated with splenectomy. RESULTS: Overall, 15.1% of patients underwent splenectomy, 7.4% underwent splenorrhaphy, and 77.5% were treated nonoperatively. Spleen injury grade, nonspleen abdominal injuries, Glasgow Coma Scale 3 to 8, and age 15 to 16 years were significant determinants of splenectomy by multivariate analysis. Children treated at pediatric trauma centers (PTC) underwent significantly fewer splenectomies. CONCLUSIONS: Injury grade, but not hemodynamic instability, was a significant independent determinant of splenectomy in children with blunt splenic trauma. Children treated at PTC are less likely to undergo splenectomy. Ongoing analysis of the management of blunt pediatric splenic injury and reduction of unnecessary splenectomies are needed to optimize care for injured children.