Receptivity of providing firearm safety storage devices to parents along with firearms safety education.

Background: In the United States, 33% of households with children contain firearms, however only one-third reportedly store firearms securely. It's estimated that 31% of unintentional firearm injury deaths can be prevented with safety devices. Our objective was to distribute safe storage devices, provide safe storage education, evaluate receptivity, and assess impact of intervention at follow-up. Method: At five independent, community safety events, parents received a safe storage device after completing a survey that assessed firearms storage methods and parental comfort with discussions regarding firearm safety. Follow-up surveys collected 4 weeks later. Data were evaluated using descriptive analysis. Result: 320 participants completed the surveys, and 288 participants were gunowners living with children. Most participants were comfortable discussing safe storage with healthcare providers and were willing to talk with friends about firearm safety. 54% reported inquiring about firearm storage in homes their children visit, 39% stored all their firearms locked-up and unloaded, 32% stored firearms/ammunition separately. 121 (37%0.8) of participants completed the follow-up survey, 84% reported using the distributed safety device and 23% had purchased additional locks for other firearms. Conclusion: Participants were receptive to firearm safe storage education by a healthcare provider and distribution of a safe storage device. Our follow up survey results showed that pairing firearm safety education with device distribution increased overall use of safe storage devices which in turn has the potential to reduce the incidence of unintentional and intentional self-inflicted firearm injuries. Providing messaging to promote utilization of safe storage will impact a firearm safety culture change.

Comparison of preoperative and intraoperative surgeon diagnosis and pathologic findings in spontaneous intestinal perforation vs necrotizing enterocolitis.

OBJECTIVE: To investigate the accuracy of preoperative and intraoperative diagnosis via comparison to pathologic diagnosis in spontaneous intestinal perforation (SIP) vs. necrotizing enterocolitis (NEC). STUDY DESIGN: A retrospective review of neonates <1500 g treated for pneumoperitoneum between 07/2004-09/2022 was conducted. Patients treated for NEC medically prior to diagnosis and those treated with drain only were excluded. Fleiss' Kappa analysis assessed agreement between all three diagnoses: preoperative, intraoperative, and pathologic. RESULT: Overall, 125 patients were included with mean birthweight 834.2 g (SD:259.2) and mean gestational age 25.8 weeks (SD:2.2). Preoperative and intraoperative diagnoses agreed in 90.3%, intraoperative and pathologic agreed in 71.1%, and preoperative and pathologic agreed in 75.2% of patients. Fleiss' Kappa was 0.55 (95% CI:0.43,0.68), indicating moderate agreement between the three diagnoses. CONCLUSION: Our study shows moderate agreement between preoperative, intraoperative, and pathologic diagnoses. Further studies investigating the clinical characteristics of SIP and NEC are needed to improve diagnostic accuracy and management.

The use and timing of angio-embolization in pediatric blunt liver and spleen injury.

BACKGROUND: Nonoperative management (NOM) is the standard of care for the management of blunt liver and spleen injuries (BLSI) in the stable pediatric patient. Angiography with embolization (AE) is utilized as an adjunctive therapy in the management of adult BLSI patients, but it is rarely utilized in the pediatric population. In this planned secondary analysis, we describe the current utilization patterns of AE in the management of pediatric BLSI. METHODS: After obtaining IRB approval at each center, cohort data was collected prospectively for children admitted with BLSI confirmed on CT at 10 Level 1 pediatric trauma centers (PTCs) throughout the United States from April 2013 to January 2016. All patients who underwent angiography with or without embolization for a BLSI were included in this analysis. Data collected included patient demographics, injury details, organ injured and grade of injury, CT finding specifics such as contrast blush, complications, failure of NOM, time to angiography and techniques for embolization. RESULTS: Data were collected for 1004 pediatric patients treated for BLSI over the study period, 30 (3.0%) of which underwent angiography with or without embolization for BLSI. Ten of the patients who underwent angiography for BLSI failed NOM. For patients with embolized splenic injuries, splenic salvage was 100%. Four of 9 patients undergoing embolization of the liver ultimately required an operative intervention, but only one patient required hepatorrhaphy and no patient required hepatectomy after AE. Few angiography studies were obtained early during hospitalization for BLSI, with only 1 patient undergoing angiography within 1 hour of arrival at the PTC, and 7 within 3 hours. CONCLUSIONS: Angioembolization is rarely utilized in the management of BLSI in pediatric trauma patients with blunt abdominal trauma and is generally utilized in a delayed fashion. However, when implemented, angioembolization is associated with 100% splenic salvage for splenic injuries. LEVEL OF EVIDENCE: Level IV, therapeutic/care management.

Initial Laparotomy Versus Peritoneal Drainage in Extremely Low Birthweight Infants With Surgical Necrotizing Enterocolitis or Isolated Intestinal Perforation: A Multicenter Randomized Clinical Trial.

OBJECTIVE: The aim of this study was to determine which initial surgical treatment results in the lowest rate of death or neurodevelopmental impairment (NDI) in premature infants with necrotizing enterocolitis (NEC) or isolated intestinal perforation (IP). SUMMARY BACKGROUND DATA: The impact of initial laparotomy versus peritoneal drainage for NEC or IP on the rate of death or NDI in extremely low birth weight infants is unknown. METHODS: We conducted the largest feasible randomized trial in 20 US centers, comparing initial laparotomy versus peritoneal drainage. The primary outcome was a composite of death or NDI at 18 to 22 months corrected age, analyzed using prespecified frequentist and Bayesian approaches. RESULTS: Of 992 eligible infants, 310 were randomized and 96% had primary outcome assessed. Death or NDI occurred in 69% of infants in the laparotomy group versus 70% with drainage [adjusted relative risk (aRR) 1.0; 95% confidence interval (CI): 0.87-1.14]. A preplanned analysis identified an interaction between preoperative diagnosis and treatment group (P = 0.03). With a preoperative diagnosis of NEC, death or NDI occurred in 69% after laparotomy versus 85% with drainage (aRR 0.81; 95% CI: 0.64-1.04). The Bayesian posterior probability that laparotomy was beneficial (risk difference <0) for a preoperative diagnosis of NEC was 97%. For preoperative diagnosis of IP, death or NDI occurred in 69% after laparotomy versus 63% with drainage (aRR, 1.11; 95% CI: 0.95-1.31); Bayesian probability of benefit with laparotomy = 18%. CONCLUSIONS: There was no overall difference in death or NDI rates at 18 to 22 months corrected age between initial laparotomy versus drainage. However, the preoperative diagnosis of NEC or IP modified the impact of initial treatment.

Multicenter retrospective comparison of spontaneous intestinal perforation outcomes between primary peritoneal drain and primary laparotomy.

PURPOSE: The purpose of our study was to compare outcomes of infants with spontaneous intestinal perforation (SIP) treated with primary peritoneal drain versus primary laparotomy. METHODS: We performed a multi-institution retrospective review of infants with diagnosis of SIP from 2012 to 2016. Clinical characteristics and outcomes were compared between infants treated with primary peritoneal drain vs infants treated with laparotomy. RESULTS: We identified 171 patients treated for SIP (drain n = 110 vs. laparotomy n = 61). There were no differences in maternal or prenatal characteristics. There were no clinically significant differences in vital signs, white blood cell or platelet measures, up to 48 h after intervention. Patients who were treated primarily with a drain were more premature (24.9 vs. 27.2 weeks, p < 0.001) and had lower median birth weight (710 g vs. 896 g, p < 0.001). No significant differences were found in complications, time to full feeds, length of stay (LOS) or mortality between the groups. Primary laparotomy group had more procedures (median number 1 vs. 2, p = 0.002). There were 32 (29%) primary drain failures whereby a laparotomy was ultimately needed. CONCLUSIONS: SIP treated with primary drain is successful in the majority of patients with no significant differences in outcomes when compared to laparotomy with stoma. THE LEVEL OF EVIDENCE: III.

Adherence to APSA activity restriction guidelines and 60-day clinical outcomes for pediatric blunt liver and splenic injuries (BLSI).

BACKGROUND: After NOM for BLSI, APSA guidelines recommend activity restriction for grade of injury +2 in weeks. This study evaluates activity restriction adherence and 60 day outcomes. METHODS: Non-parametric tests and logistic regression were utilized to assess difference between adherent and non-adherent patients from a 3-year prospective study of NOM for BLSI (≤18 years). RESULTS: Of 1007 children with BLSI, 366 patients (44.1%) met the inclusion criteria of a completed 60 day follow-up; 170 (46.4%) had liver injury, 159 (43.4%) had spleen injury and 37 (10.1%) had both. Adherence to recommended activity restriction was claimed by 279 (76.3%) patients; 49 (13.4%) reported non-adherence and 38 (10.4%) patients had unknown adherence. For 279 patients who adhered to activity restrictions, unplanned return to the emergency department (ED) was noted for 35 (12.5%) with 16 (5.7%) readmitted; 202 (72.4%) returned to normal activity by 60 days. No patient bled after discharge. There was no statistical difference between adherent patients (n = 279) and non-adherent (n = 49) for return to ED (χ2 = 0.8 [p < 0.4]) or readmission (χ2 = 3.0 [p < 0.09]); for 216 high injury grade patients, there was no difference between adherent (n = 164) and non-adherent (n = 30) patients for return to ED (χ2 = 0.6 [p < 0.4]) or readmission (χ2 = 1.7 [p < 0.2]). CONCLUSION: For children with BLSI, there was no difference in frequencies of bleeding or ED re-evaluation between patients adherent or non-adherent to the APSA activity restriction guideline. LEVEL OF EVIDENCE: Level II, Prognosis.

Structural airway abnormalities contribute to dysphagia in children with esophageal atresia and tracheoesophageal fistula.

BACKGROUND: Long-term dysphagia occurs in up to 50% of repaired esophageal atresia and tracheoesophageal fistula (EA/TEF) patients. The underlying factors are unclear and may include stricture, esophageal dysmotility, or associated anomalies. Our purpose was to determine whether structural airway abnormalities (SAA) are associated with dysphagia in EA/TEF. METHODS: We conducted a retrospective chart review of children who underwent EA/TEF repair in our hospital system from 2007 to 2016. Children with identified SAA (oropharyngeal abnormalities, laryngeal clefts, laryngomalacia, vocal cord paralysis, and tracheomalacia) were compared to those without airway abnormalities. Dysphagia outcomes were determined by the need for tube feeding and the modified pediatric Functional Oral Intake Scale (FOIS) at 1 year. RESULTS: SAA was diagnosed in 55/145 (37.9%) patients with EA/TEF. Oropharyngeal aspiration was more common in children with SAA (58.3% vs. 36.4%, p=0.028). Children with SAA were more likely to require tube feeding both at discharge (79.6% vs. 48.3%, p<0.001) and at 1 year (52.7% vs. 13.6%, p<0.001) and had lower mean FOIS (4.18 vs. 6.21, p<0.001). In the logistic regression model adjusting for gestational age, long gap EA, and esophageal stricture, the presence of SAA remained a significant risk factor for dysphagia (OR 4.17 (95% CI 1.58-11.03)). CONCLUSION: SAA are common in children with EA/TEF and are associated with dysphagia, even after accounting for gestational age, esophageal gap and stricture. This study highlights the need for a multidisciplinary approach, including early laryngoscopy and bronchoscopy, in the evaluation of the EA/TEF child with dysphagia. LEVEL OF EVIDENCE: Level II retrospective prognostic study.

Pathogenesis of NEC: Role of the innate and adaptive immune response.

Necrotizing enterocolitis (NEC) is a devastating disease in premature infants with high case fatality and significant morbidity among survivors. Immaturity of intestinal host defenses predisposes the premature infant gut to injury. An abnormal bacterial colonization pattern with a deficiency of commensal bacteria may lead to a further breakdown of these host defense mechanisms, predisposing the infant to NEC. Here, we review the role of the innate and adaptive immune system in the pathophysiology of NEC.

The association of type of surgical closure on length of stay among infants with gastroschisis born≥34 weeks' gestation.

BACKGROUND/PURPOSE: The optimal surgical approach in infants with gastroschisis (GS) is unknown. The purpose of this study was to estimate the association between staged closure and length of stay (LOS) in infants with GS. DESIGN/METHODS: We used the Children's Hospital Neonatal Database to identify surviving infants with GS born ≥34 weeks' gestation referred to participating NICUs. Infants with complex GS, bowel atresia, or referred after 2 days of age were excluded. The primary outcome was LOS; multivariable linear regression was used to quantify the relationship between staged closure and LOS. RESULTS: Among 442 eligible infants, staged closure occurred in 68.1% and was associated with an increased median LOS relative to odds ration (OR):primary closure (37 vs. 28 days, p<0.001). This association persisted in the multivariable equation (ß=1.35, 95% CI: 1.21, 1.52, p<0.001) after adjusting for the presence of necrotizing enterocolitis, short bowel syndrome, and central-line associated bloodstream infections. CONCLUSIONS: In this large, multicenter cohort of infants with GS, staged closure was independently associated with increased LOS. These data can be used to enhance antenatal and pre-operative counseling and also suggest that some infants who receive staged closure may benefit from primary repair.

Cytokine levels in the preterm infant with neonatal intestinal injury.

OBJECTIVES: The purpose of this study is to characterize the cytokine response of preterm newborns with surgical necrotizing enterocolitis (NEC) or spontaneous intestinal perforation (SIP) before surgical treatment and to relate these finding to intestinal disease (NEC vs. SIP). STUDY DESIGN: The study was a 14-month prospective, cohort study of neonates undergoing surgery or drainage for NEC or SIP or surgical ligation of patent ductus arteriosus (PDA). Multiplex cytokine detection technology was used to analyze six inflammatory markers: interleukin-2, interleukin-6 (IL-6), interleukin-8 (IL-8), interleukin-1 ß (IL-1ß), interferon-gamma, and tumor necrosis factor-α (TNF-α). RESULTS: Patients with NEC had much higher median preoperative levels of IL-6 (NEC: 8,381 pg/mL; SIP: 36 pg/mL; PDA: 25 pg/mL, p < 0.001), IL-8 (NEC: 18,438 pg/mL; SIP: 2,473 pg/mL; PDA: 1,110 pg/mL, p = 0.001), TNF-α (NEC: 161 pg/mL; SIP: 77 pg/mL; PDA: 71 pg/mL, p < 0.001), and IL-1ß (NEC: 85 pg/mL; SIP: 31 pg/mL; PDA: 24 pg/mL, p = 0.001). Patients with NEC totalis (NEC-totalis had the highest levels of IL-8 and were significantly different from infants with limited NEC (28,141 vs. 11,429 pg/mL, p = 0.03). CONCLUSION: Surgical NEC is a profoundly more proinflammatory disease than SIP. The cytokine profiles of patients with SIP are closer to those of a nonseptic surgical neonate.

Hirschsprung's disease in the preterm infant: implications for diagnosis and outcome.

Hirschsprung's disease (HD), congenital absence of ganglion cells, is considered uncommon in preterm infants. The aim was to describe the frequency, presentation, and surgical outcomes of preterm infants with HD. A retrospective cohort study was conducted of all patients diagnosed with HD from 2002 to 2012 at a single children's hospital. Clinical presentation and surgical outcomes were obtained for term (37 weeks of gestation or greater) and preterm infants. One hundred twenty-nine subjects with HD were identified, 24 (19%) preterm and 105 (81%) term. Preterm infants were more likely to be diagnosed after 30 days of life (66.7 vs 37.1%, P < 0.01; median age 2.9 vs 0.3 months, P < 0.05) and to have associated major congenital anomalies (45.8 vs 20.0%, P < 0.01). Fewer preterm infants had primary pull-through operations (45.8 vs 76.2%, P < 0.005). Preterm infants were more likely to have an episode of Hirschsprung's-associated enterocolitis (45.8 vs 24.0%, P < 0.05) but were not more likely to die from any cause (8.3 vs 5.8%, P = 0.64). HD may be more common in preterm infants than previously recognized, and increased comorbidities in these patients may lead to delayed diagnosis and increased morbidity. HD should be considered in the preterm infant presenting with a bowel obstruction, especially when accompanied by associated anomalies.

Pencils and pens: an under-recognized source of penetrating injuries in children.

Unlike other sharp objects, pens and pencils are readily available to children both at home and school. Although case reports are published, no series of pen or pencil injuries have been reported in the recent literature. We therefore reviewed the incidence and injury profiles of writing instruments as compared with other sources of penetrating trauma. The trauma registry from a large urban pediatric hospital system was queried for nonmissile, nonbite penetrating injuries from 2005 through 2009. Retrospective data was collected on demographics, injuries, operations, admissions, and mortalities. Additionally, data regarding pen and pencil injuries from 2009 to 2010 were collected prospectively, and one case from 2003 was included retrospectively. Fourteen injuries from writing instruments were seen and involved the head and neck (9), chest (1), bladder/perineum (2), and extremities (2). Eleven children were admitted and eight required surgical intervention. One child died from a transhemispheric brain injury after intraorbital penetration by a pencil. Penetrating trauma from writing instruments is not an uncommon source of injury and often requires surgical intervention to remove the object. Injuries from pens and pencils can be severe or even fatal. Appropriate parent and teacher education regarding the potential risks may help to prevent such injuries.

Pseudoangiomatous stromal hyperplasia of the breast in pediatric patients: an underrecognized entity.

Pseudoangiomatous stromal hyperplasia (PASH) is a benign lesion consisting of mammary stromal proliferation with anastomosing slits mimicking vascular spaces. Grossly, it most often resembles fibroadenoma, but may commonly be confused with angiosarcoma and other types of benign vascular proliferations. While PASH has been described in female and male adults since the mid-1980s, there have been only a few accounts in the pediatric population. We present a series of 12 pediatric patients with PASH, including a 3-year-old male, who we believe to be the youngest patient to present with this entity. In our study, PASH was found in 12% of tumors diagnosed preoperatively as fibroadenomas and in 12% of cases diagnosed preoperatively as gynecomastia. Our series documents that PASH is not uncommon in pediatric breast pathology and delineates important differences between adult and pediatric presentations of this entity.

Is the use of laparoscopy to determine presence of contralateral patent processus vaginalis justified in children greater than 2 years of age?

PURPOSE: Contralateral inguinal hernia exploration in cases of unilateral inguinal hernia remains a controversial topic. The authors have been using the in-line laparoscopic technique of contralateral evaluation for unilateral inguinal hernia in children less than 2 years of age. Because of the case of the procedure and lack of morbidity, we decided to expand the use of this procedure up to age 8 years in January 2000. The purpose of this study is to evaluate if the incidence of contralateral hernia in children greater than 2 years justifies the procedure. METHODS: This is a retrospective study of all children who underwent contralateral exploration for unilateral inguinal exploration over a 20-month period. The procedure was offered routinely to all patients up to age 8 years. During the repair, the contralateral inguinal ring was examined laparoscopically using the in-line technique for the presence of a contralateral hernia. The incidence of contralateral hernia was determined, and the results were stratified by age. Patients who underwent unilateral inguinal hernia repair without laparoscopic contralateral exploration or bilateral inguinal hernia repair without laparoscopic contralateral explorations were excluded from the study. RESULTS: A total of 284 laparoscopic explorations were performed. Positive explorations were seen in 65 of 171 (38%) of children less than 2 years of age, 19 of 101 (20%) of children 2 to 8 years of age, and 1 of 12 children greater than 8 years of age (8%). There were no operative complications. CONCLUSIONS: Laparoscopic contralateral exploration is safe and effective. Because of the low morbidity, the risk to benefit ratio warrants its use in children up to 8 years of age. This sample size is too small to make any meaningful statement in children older than 8 years.

Aberrant fibroblast growth factor receptor 2 signalling in esophageal atresia with tracheoesophageal fistula.

BACKGROUND: Although the pathogenesis of esophageal atresia with tracheoesophageal fistula (EA/TEF) remains unknown, it has been shown that despite its esophageal appearance, the fistula tract originates from respiratory epithelium. The authors now hypothesize that defects in fibroblast growth factor (FGF) signaling contribute to the esophaguslike phenotype of the fistula tract. FGF2R is critical to normal lung morphogenesis and occurs in 2 isoforms (FGF2RIIIb and FGF2RIIIc), each with different ligand-binding specificity. To characterize FGF signaling in the developing EA/TEF, the authors analyzed levels of FGF2R splice variants in experimental EA/TEF. METHODS: The standard Adriamycin-induced EA/TEF model in rats was used. Individual foregut components from Adriamycin-treated and control embryos were processed for real-time, fluorescence-activated semiquantitative reverse transcriptase polymerase chain reaction on gestational days 12.5 and 13.5. RESULTS: Both fistula tract and Adriamycin-treated or normal esophagus showed significantly lower levels of FGF2RIIIb than either Adriamycin-treated lung buds (E12.5, P =.02; E13.5, P <.005) or normal lung buds (E12.5, P <.005; E13.5, P <.01). At E13.5, the fistula tract had lower levels of FGF2RIIIc than either treated (P <.01) or normal lung (P <.05). CONCLUSIONS: Levels of FGF2R in the developing fistula tract resemble that of distal esophagus rather than developing lung. This defect in FGF2RIIIb signaling may account for the nonbranching, esophaguslike phenotype of the fistula, despite its respiratory origin.

Defective sonic hedgehog signaling in esophageal atresia with tracheoesophageal fistula.

BACKGROUND: The pathogenesis of esophageal atresia and tracheoesophageal fistula (EA/TEF) remains unknown. We have found previously that an initial esophageal atresia, followed by an abnormal (absent) branching pattern of the middle branch of a trifurcation of the lung/tracheal bud, leads to the neonatal finding of TEF. Mice null mutant for hedgehog signaling can experience the development of EA/TEF, but the mechanism for this development is also unknown. Given that EA/TEF in humans appears not to be due to genetic defects, a hedgehog mutation cause seems very unlikely. However, defective hedgehog signaling that is caused by environmental effects in the human embryo likely could be implicated. We studied a teratogen-induced model of EA/TEF to determine the mechanism by which defective hedgehog signaling may lead to EA/TEF. METHODS: We injected Adriamycin into pregnant rats to induce EA/TEF in rat embryos. We first quantified sonic hedgehog (Shh) signaling pathway molecule expression using real-time, semiquantitative reverse-transcriptase polymerase chain reaction for Shh, Shh receptors (patched and smoothened), and downstream intracellular targets of those receptors (Gli family members). On the basis of these findings, we then developed an in vitro culture system for the day-12 embryonic TEF and manipulated Shh signaling using either exogenous Shh or Shh inhibitors. RESULTS: By reverse transcriptase-polymerase chain reaction, a unique difference between the fistula tract and control tissues was that Gli-2 (downstream signaling molecule of Shh) messenger RNA levels were much lower in the fistula tract than in the adjacent esophagus (P =.002). Surprisingly, in the culture experiments, the fistula tract was induced to branch by exogenous Shh. Such branching of the fistula was unexpected and further supports the presumed respiratory origin of the fistula tract because the normal lung, but not normal esophagus, branched in response to Shh. The Shh inhibitor had no effect, which indicated that defective signaling, rather than hyperfunctioning Shh, is critical to the nonbranching phenotype of the fistula tract in TEF. CONCLUSIONS: The recapitulation of respiratory developmental morphogenesis by the fistula tract of TEF in the presence of exogenous Shh, together with the quantitative reduction in normal, endogenous levels of Gli-2, strongly suggests that 1 mechanism for the formation of the fistula tract is the lack of proper Shh signaling because of Gli-2 deficiency, with subsequent straight, nonbranching caudal growth of the fistula tract. This deficiency can be rescued by excess exogenous Shh, thus reestablishing respiratory morphogenesis.

Fibroblast growth factor signaling in the developing tracheoesophageal fistula.

BACKGROUND/PURPOSE: The Adriamycin-induced rat model of esophageal atresia and tracheoesophageal fistula (EA/TEF) provides a reliable system for the study of EA/TEF pathogenesis. The authors previously hypothesized that faulty branching lung morphogenesis pathways were a critical component of its pathogenesis. The authors have found evidence for faulty fibroblast growth factor (FGF) signaling related to epithelial-mesenchymal interactions in the fistula tract. To better define FGF signaling, the differential expression of FGF ligands and their receptors between lung, fistula tract, and esophagus are described. METHODS: Time-dated pregnant, Sprague-Dawley rats were injected with Adriamycin (2 mg/kg intraperitoneally) on days 6 through 9 of gestation. Tissues were processed for histology and reverse transcriptase polymerase chain reaction. FGF-1, -7 and -10 were measured from whole lung, fistula tract, and esophagus of TEF or normal embryos. Expression of FGF2RIIIb and FGF2RIIIc receptors was measured in isolated epithelium and mesenchyme of lung and fistula tract of TEF embryos as well as lung and esophagus from normal controls. RESULTS: FGF-1 mRNA was present in the fistula tract and normal and Adriamycin-exposed lung but absent from whole esophagus. Interestingly, FGF-7 mRNA was present only in normal lung. FGF-10 was present in all tissues examined. FGF2RIIIb mRNA was absent in fistula mesenchyme but present in all other tissues examined. However, the splice variant FGF2RIIIc mRNA was present in all tissues examined. CONCLUSIONS: These findings support defective FGF signaling in the rat model of EA/TEF. Absence of FGF-7 mRNA in Adriamycin-exposed tissues suggests the primary effect of Adriamycin may be to inhibit FGF-7 expression. Moreover, absence of FGF2RIIIb in fistula mesenchyme may be caused by loss of positive feedback from FGF-7, its normal obligate ligand. Understanding these specific defects in FGF signaling may provide insight into faulty mechanisms of EA/TEF.

Retinoid signaling controls mouse pancreatic exocrine lineage selection through epithelial-mesenchymal interactions.

BACKGROUND & AIMS: The early embryonic pancreas gives rise to exocrine (ducts and acini) and endocrine lineages. Control of exocrine differentiation is poorly understood, but may be a critical avenue through which to manipulate pancreatic ductal carcinoma. Retinoids have been shown to change the character of pancreatic ductal cancer cells to a less malignant phenotype. We have shown that 9-cis retinoic acid (9cRA) inhibits acinar differentiation in the developing pancreas, in favor of ducts, and we wanted to determine the role of retinoids in duct versus acinar differentiation. METHODS: We used multiple culture systems for the 11-day embryonic mouse pancreas. RESULTS: Retinoic acid receptor (RAR)-selective agonists mimicked the acinar suppressive effect of 9cRA, suggesting that RAR-RXR heterodimers were critical to ductal differentiation. RARalpha was only expressed in mesenchyme, whereas RXRalpha was expressed in epithelium and mesenchyme. Retinaldehyde dehydrogenase 2, a critical enzyme in retinoid synthesis, was expressed only in pancreatic epithelium. 9cRA did not induce ductal differentiation in the absence of mesenchyme, implicating a requirement for mesenchyme in 9cRA effects. Mesenchymal laminin is necessary for duct differentiation, and retinoids are known to enhance laminin expression. In 9cRA-treated pancreas, immunohistochemistry for laminin showed a strong band of staining around ducts, and blockage of laminin signaling blocked all 9cRA effects. Western blot and RT-PCR of pancreatic mesenchyme showed laminin-beta1 protein and mRNA induction by 9cRA. CONCLUSIONS: Retinoids regulate exocrine lineage selection through epithelial-mesenchymal interactions, mediated through up-regulation of mesenchymal laminin-1.

Complete discontinuity of the distal fistula tract from the developing gut: direct histologic evidence for the mechanism of tracheoesophageal fistula formation.

The embryogenesis of tracheoesophageal anomalies remains controversial. The purpose of this study was to better define the embryogenesis of developing esophageal atresia with tracheoesophageal fistula (EA/TEF), with specific attention to the controversial issue of whether a discontinuity exists in the foregut during its development of EA/TEF. Pregnant outbred rats were injected with adriamycin (2 mg/kg i.p.) on days 6-9 of gestation (E6-E9). At E12.5 and 13.5, microdissection of the entire foregut was performed. Foreguts were examined by phase microscopy, and serial, precisely transverse sections were created for hematoxylin and eosin (H&E) staining. Gross microdissection of the developing foregut at E12.5 (n = 9) revealed a blind-ending, bulbous fistula tract arising from the middle branch of the tracheal trifurcation (as seen by direct and phase microscopy). No connection with the gut could be appreciated at E12.5, but by E13.5 (n = 10) there was an obvious connection between the fistula and the stomach. Serial H&E transverse sections also demonstrated a blind-ending fistula tract arising from the trachea at E12.5. This fistula tract was clearly discontinuous from the developing stomach, which appeared much further caudal to the end of the fistula tract. These results strongly support a model of experimental TEF wherein the fistula tract arises from a trifurcation of the trachea, and (only during a specific gestational window between days 12.5 and 13.5) there is discontinuity between the fistula tract and the stomach. By day 13.5, the fistula joins with the stomach anlage. These observations in the developing EA/TEF should help to resolve the controversy about the mechanism of EA/TEF formation.