Cardiovascular malformations in congenital diaphragmatic hernia: human and experimental studies

Beyond the diaphragm and the lung: a multisystem approach to understanding congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a birth defect characterized by the incomplete closure of the diaphragm and herniation of abdominal organs into the chest during gestation. This invariably leads to an impairment in fetal lung development (pulmonary hypoplasia) that involves the pulmonary vessels (vascular remodeling) leading to postnatal pulmonary hypertension. Moreover, approximately 60% of CDH survivors have long-term comorbidities, including critical cardiac anomalies, neurodevelopmental impairment, gastroesophageal reflux, and musculoskeletal malformations. While the pathophysiology of the diaphragmatic defect and pulmonary hypoplasia have been studied in detail over the decades, less is known about the other organs affected in CDH. In this review, we searched the literature for reports on other organs beyond the lung and diaphragm in human and experimental models of CDH. We found studies reporting gross morphometric changes and alterations to biological pathways in the heart, brain, liver, kidney, gastrointestinal tract, and musculoskeletal system. Given the paucity of literature and the importance that these comorbidities play in the life of patients with CDH, further studies are needed to comprehensively uncover the pathophysiology of the changes observed in these other organs.

Overexpression of miR-455-5p affects retinol (vitamin A) absorption by downregulating STRA6 in a nitrofen-induced CDH with lung hypoplasia rat model

Lung hypoplasia is the main cause of congenital diaphragmatic hernia (CDH)-associated death but pathogenesis remains unclear. MiR-455-5p is involved in lung hypoplasia. We hypothesized that nitrofen causes abnormal miR-455-5p expression during lung development and designed this study to determine the relationship between miR-455-5p, stimulated by retinoic acid 6 (STRA6), and retinol in a nitrofen-induced CDH with lung hypoplasia rat model. Nitrofen or olive oil was administered to Sprague-Dawley rats by gavage on day 9.5 of gestation, and the rats were divided into a nitrofen group and a control group (n = 6). The left lung of fetuses was dissected on day 15.5. The expression of miR-455-5p or STRA6 messenger RNA (mRNA) was determined by quantitative real-time polymerase chain reaction. Average integrated optical density (IOD) of STRA6 protein was determined by immunofluorescence histochemistry. The average retinol level was detected by enzyme-linked immunosorbent assay (n = 6 lungs, respectively). Compared with the control group, the nitrofen group exhibited significantly increased miR-455-5p expression levels (29.450 ± 9.253 vs 5.955 ± 2.330; P = .00045) and significantly decreased STRA6 mRNA levels (0.197 ± 0.097 vs 0.588 ± 0.184; P = .0047). In addition, the average IOD of the STRA6 protein was significantly lower in the nitrofen group (805.643 ± 291.182 vs 1616.391 ± 572.308, P = .015), and the average retinol level was significantly reduced (4.013 ± 0.195 vs 5.317 ± 0.337 µg/L, P = .000). In summary, the overexpression of miR-455-5p affected retinol absorption by downregulating STRA6 in the nitrofen-induced CDH with lung hypoplasia rat model, and this downregulation may be one cause of CDH with lung hypoplasia.

The effect of congenital diaphragmatic hernia on the development of left-sided heart structures

INTRODUCTION

Patients with congenital diaphragmatic hernias often have concomitant congenital heart disease (CHD), with small left-sided cardiac structures as a frequent finding. The goal of this study is to evaluate which left-sided heart structures are affected in neonates with congenital diaphragmatic hernias.

METHODS

Retrospective review of neonates between May 2007 and April 2015 with a diagnosis of a congenital diaphragmatic hernia was performed. Clinical and echocardiographic data were extracted from the electronic medical record and indexed to body surface area and compared to normative values. Univariable regression models assessed for associations between different variables and length of stay.

RESULTS

Data of 52 patients showed decreased mean z scores for the LVIDd (-3.16), LVIDs (-3.05), aortic annulus (-1.68), aortic sinuses (-2.11), transverse arch (-3.11), and sinotubular junction (-1.47) with preservation of the aorta at the diaphragm compared to age-matched normative data with similar body surface areas. Regression analysis showed a percent reduction in length of stay per 1 mm size increase for LVIDd (8%), aortic annulus (27%), aortic sinuses (18%), sinotubular junctions (20%), and transverse arches (25%).

CONCLUSIONS

Patients with congenital diaphragmatic hernias have significantly smaller left-sided heart structures compared to age-matched normative data. Aortic preservation at the diaphragm provides evidence for a mass effect aetiology with increased right-to-left shunting at the fetal ductus resulting in decreased size. Additionally, length of stay appears to be prolonged with decreasing size of several of these structures. These data provide quantitative evidence of smaller left-sided heart structures in patients with congenital diaphragmatic hernias.

Congenital heart disease associated with congenital diaphragmatic hernia: A systematic review on incidence, prenatal diagnosis, management, and outcome

PURPOSE

The purpose of this study was to evaluate the impact of congenital heart disease (CHD) on infants with congenital diaphragmatic hernia (CDH).

METHODS

Using a defined search strategy (PubMed, Cochrane, Embase, Web of Science MeSH headings), we searched studies reporting the incidence, management, and outcome of CDH infants born with associated CHD.

RESULTS

Of 6410 abstracts, 117 met criteria. Overall, out of 28,974 babies with CDH, 4427 (15%) had CHD, of which 42% were critical. CDH repair was performed in a lower proportion of infants with CHD (72%) than in those without (85%; p < 0.0001). Compared to CDH babies without CHD, those born with a cardiac lesion were more likely to have a patch repair (45% vs. 30%; p < 0.01) and less likely to undergo minimally invasive surgery (5% vs. 17%; p < 0.0001). CDH babies with CHD had a lower survival rate than those without CHD (52 vs. 73%; p < 0.001). Survival was even lower (32%) in babies with critical CHD.

CONCLUSION

CHD has a strong impact on the management and outcome of infants with CDH. The combination of CDH and CHD results in lower survival than those without CHD or an isolated cardiac defect. Further studies are needed to address some specific aspects of the management of this fragile CDH cohort.

TYPE OF STUDY

Systematic review and meta-analysis.

LEVEL OF EVIDENCE

Level III.

Congenital diaphragmatic hernia after exposure to a triple retinoic acid antagonist during pregnancy

AIM

To establish a mouse model for the study of congenital defects, using exposure of pregnant females to the teratogen BMS-189453, a multiple retinoic acid competitive antagonist.We found not less than 60% of fetuses had transposition of the great arteries and l5% had other congenital heart defects such as double outlet right ventricle, tetralogy of Fallot, truncus and right aortic arch. Newborns exposed in utero to BMS-189453 were affected by thymus aplasia or hypoplasia, and severe congenital anomalies of the central nervous system due to neural tube defects. An anterior rotation of the right lung was also frequently present in our model. We also report a case of murine congenital diaphragmatic hernia associated with thymic aplasia and transposition of the great arteries.

CONCLUSION

These findings support the hypothesis that the combination of diaphragmatic hernia and congenital heart defects may be related to an alteration of the retinoic acid signaling pathways.

Complications in neonatal surgery

Neonatal surgery is recognized as an independent discipline in general surgery, requiring the expertise of pediatric surgeons to optimize outcomes in infants with surgical conditions. Survival following neonatal surgery has improved dramatically in the past 60 years. Improvements in pediatric surgical outcomes are in part attributable to improved understanding of neonatal physiology, specialized pediatric anesthesia, neonatal critical care including sophisticated cardiopulmonary support, utilization of parenteral nutrition and adjustments in fluid management, refinement of surgical technique, and advances in surgical technology including minimally invasive options. Nevertheless, short and long-term complications following neonatal surgery continue to have profound and sometimes lasting effects on individual patients, families, and society.

Electrical and mechanical stimulation of cardiac cells and tissue constructs

The field of cardiac tissue engineering has made significant strides over the last few decades, highlighted by the development of human cell derived constructs that have shown increasing functional maturity over time, particularly using bioreactor systems to stimulate the constructs. However, the functionality of these tissues is still unable to match that of native cardiac tissue and many of the stem-cell derived cardiomyocytes display an immature, fetal like phenotype. In this review, we seek to elucidate the biological underpinnings of both mechanical and electrical signaling, as identified via studies related to cardiac development and those related to an evaluation of cardiac disease progression. Next, we review the different types of bioreactors developed to individually deliver electrical and mechanical stimulation to cardiomyocytes in vitro in both two and three-dimensional tissue platforms. Reactors and culture conditions that promote functional cardiomyogenesis in vitro are also highlighted. We then cover the more recent work in the development of bioreactors that combine electrical and mechanical stimulation in order to mimic the complex signaling environment present in vivo. We conclude by offering our impressions on the important next steps for physiologically relevant mechanical and electrical stimulation of cardiac cells and engineered tissue in vitro.

Prevention of pulmonary hypoplasia and pulmonary vascular remodeling by antenatal simvastatin treatment in nitrofen-induced congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) has a high mortality rate mainly due to lung hypoplasia and persistent pulmonary hypertension of the newborn (PPHN). Simvastatin has been shown to prevent the development of pulmonary hypertension (PH) in experimental models of PH. We, therefore, hypothesized that antenatal simvastatin would attenuate PPHN in nitrofen-induced CDH in rats. The efficacy of antenatal simvastatin was compared with antenatal sildenafil, which has already been shown to improve pathological features of PPHN in nitrofen-induced CDH. On embryonic day (E) 9.5, nitrofen or vehicle was administered to pregnant Sprague-Dawley rats. On E11, nitrofen-treated rats were randomly assigned to antenatal simvastatin (20 mg·kg(-1)·day(-1) orally), antenatal sildenafil (100 mg·kg(-1)·day(-1) orally), or placebo administration from E11 to E21. On E21, fetuses were delivered by cesarean section, killed, and checked for left-sided CDH. Lung tissue was then harvested for further pathobiological evaluation. In nitrofen-induced CDH, simvastatin failed to reduce the incidence of nitrofen-induced CDH in the offspring and to increase the body weight, but improved the lung-to-body weight ratio and lung parenchyma structure. Antenatal simvastatin restored the pulmonary vessel density and external diameter, and reduced the pulmonary arteriolar remodeling compared with nitrofen-induced CDH. This was associated with decreased lung expression of endothelin precursor, endothelin type A and B receptors, endothelial and inducible nitric oxide synthase, together with restored lung activation of apoptotic processes mainly in the epithelium. Antenatal simvastatin presented similar effects as antenatal therapy with sildenafil on nitrofen-induced CDH. Antenatal simvastatin improves pathological features of lung hypoplasia and PPHN in experimental nitrofen-induced CDH.

Animal Models of Pulmonary Hypertension: Matching Disease Mechanisms to Etiology of the Human Disease

Recently a great deal of progress has been made in our understanding of pulmonary hypertension (PH). Research from the past 30 years has resulted in newer treatments that provide symptomatic improvements and delayed disease progression. Unfortunately, the cure for patients with this lethal syndrome remains stubbornly elusive. With the relative explosion of scientific literature regarding PH, confusion has arisen regarding animal models of the disease and their correlation to the human condition. This short review uniquely focuses on the clear and present need to better correlate mechanistic insights from existing and emerging animal models of PH to specific etiologies and histopathologies of human PH. A better understanding of the pathologic processes in various animal models and how they relate to the human disease should accelerate the development of newer and more efficacious therapies.

Congenital diaphragmatic hernia: defect size correlates with developmental defect

PURPOSE

The aim of our study was to elucidate if the defect size reflects the magnitude of the developmental defect in patients with CDH.

METHODS

All patients recorded in the CDH Study Group registry between January 1, 2007, and December 31, 2010, and with defect classification were included in the study. They were divided according to defect size (A-D) and compared for: gestational age (GA), birth weight (BW), number of abnormal organ systems, prevalence of associated anomalies, cardiovascular malformations (CVM), chromosomal anomalies, liver in the chest, and hernia sac.

RESULTS

A total of 1350 of 1778 patients had defect classification: 173 A, 557 B, 438 C, and 182 D. Mortality rate was 0.6%, 5.3%, 22.6%, and 45.6% in group A, B, C, and D, respectively, (p<0.0001; p for trend <0.0001). GA, BW, prevalence of associated anomalies, particularly CVM, number of abnormal organ systems, and prevalence of sac were significantly different between the groups, with a significant reduction of GA, BW, and prevalence of sac. There was an increase in prevalence of associated anomalies, liver in the chest, and number of abnormal systems as the defect size increased.

CONCLUSION

Defect size is directly correlated with mortality rate, prevalence of other anomalies (particularly CVM), and number of abnormal systems, and inversely with GA, BW, and prevalence of hernia sac. The defect size may be a marker for the magnitude of developmental abnormality, thereby explaining its relationship with the outcome.

Changes in the expression of vascular endothelial growth factor after fetal tracheal occlusion in an experimental model of congenital diaphragmatic hernia

Introduction. Vascular endothelial growth factor (VEGF), an angiogenic factor secreted by type II pneumocytes, could play a role in congenital diaphragmatic hernia (CDH) pathogenesis. Animal studies suggest that VEGF accelerates lung growth. Aim. To quantify VEGF on fetal lungs in a nitrofen rat model for CDH and to analyze the effect of tracheal occlusion (TO) in VEGF in fetal lung rats after nitrofen and in control rats not exposed to nitrofen. Methods. Pregnant rats received nitrofen on day 9.5 of gestation. Fetuses were divided into 2 groups: those that underwent TO on day 20 and those that did not. On day 21, fetuses were delivered, and the lungs were dissected for subsequent VEGF quantification. Results. CDH was detected in 43% of the fetuses that received nitrofen. Fetuses with CDH showed significantly reduced lung weight/fetal weight ratio and lower VEGF levels than the remainder. A higher VEGF value was observed after TO. Conclusions. VEGF protein was significantly lower in fetuses with CDH. TO induced a significant increase in VEGF compared to the fetuses that did not undergo TO. Although not statistically significant, we observed higher VEGF levels in fetuses with CDH and TO compared to fetuses with CDH and no further intervention.

Congenital diaphragmatic hernia

Congenital Diaphragmatic Hernia (CDH) is defined by the presence of an orifice in the diaphragm, more often left and posterolateral that permits the herniation of abdominal contents into the thorax. The lungs are hypoplastic and have abnormal vessels that cause respiratory insufficiency and persistent pulmonary hypertension with high mortality. About one third of cases have cardiovascular malformations and lesser proportions have skeletal, neural, genitourinary, gastrointestinal or other defects. CDH can be a component of Pallister-Killian, Fryns, Ghersoni-Baruch, WAGR, Denys-Drash, Brachman-De Lange, Donnai-Barrow or Wolf-Hirschhorn syndromes. Some chromosomal anomalies involve CDH as well. The incidence is < 5 in 10,000 live-births. The etiology is unknown although clinical, genetic and experimental evidence points to disturbances in the retinoid-signaling pathway during organogenesis. Antenatal diagnosis is often made and this allows prenatal management (open correction of the hernia in the past and reversible fetoscopic tracheal obstruction nowadays) that may be indicated in cases with severe lung hypoplasia and grim prognosis. Treatment after birth requires all the refinements of critical care including extracorporeal membrane oxygenation prior to surgical correction. The best hospital series report 80% survival but it remains around 50% in population-based studies. Chronic respiratory tract disease, neurodevelopmental problems, neurosensorial hearing loss and gastroesophageal reflux are common problems in survivors. Much more research on several aspects of this severe condition is warranted.

Retinoic acid rescues deficient airway innervation and peristalsis of hypoplastic rat lung explants

BACKGROUND

Bronchial peristalsis modulates lung growth and is deficient in hypoplastic nitrofen-exposed rat lung explants. Retinoic acid (RA) rescues lung hypoplasia. This study examines whether decreased bronchial innervation contributes to this developmental deficiency and if RA is able to recover bronchial innervation and motility.

MATERIAL AND METHODS

After IRB approval, pregnant rats received either 100 mg nitrofen or vehicle on gestational day 9.5 (E9.5). Embryonic lung primordia harvested on E13 were cultured for 72 h and RA was added daily to the medium when appropriate. Lung growth was assessed by counting the number of terminal buds and measuring explant surface, total DNA and protein in control, control + RA, nitrofen and nitrofen + RA groups. Peristaltic contractions were recorded for 10 min under an inverted microscope. Lung explants stained for anti-protein gene product 9.5 (PGP 9.5) and smooth muscle α-actin were examined under a confocal microscope for depicting the specific relationship between neural and smooth muscle cells. PGP 9.5 and smooth muscle α-actin levels were quantified by Western blot analysis for assessing the neural and muscle cell expressions. Comparisons between groups were made with non-parametric tests.

RESULTS

The number of terminal buds, the explants' surface and the DNA and protein contents were significantly decreased in nitrofen-exposed lungs in comparison with controls. In contrast, these measurements were normal in explants exposed to both nitrofen and RA. Bronchial peristalsis (contractions/min) was significantly decreased in nitrofen-exposed lungs in comparison with controls; in contrast, in nitrofen + RA lungs it was similar to controls. In all study groups, the airways were surrounded by smooth muscle and ensheathed in a plexus of nerve fibers containing ganglia. PGP 9.5 protein levels were decreased in nitrofen-exposed lungs, but they normalized when RA was added. No differences were found in α-actin protein levels. Explants exposed only to RA were similar to control.

CONCLUSIONS

Lung growth, bronchial innervation and peristalsis are decreased in nitrofen-exposed lung explants and are rescued by RA. If deficient airway innervation contributing to dysmotility and pulmonary hypoplasia can be pharmacologically rescued, new relatively simple prenatal interventions could be envisioned.

Microscopic magnetic resonance imaging of the thoracic venous system in rats with congenital diaphragmatic hernia

BACKGROUND/AIM

Infants and rats with congenital diaphragmatic hernia (CDH) have malformations of the heart and the great arteries caused by neural crest (NC) dysregulation during embryogenesis. Abnormally narrow jugular veins have been found in babies during cannulation for ECMO. However, the venous system has not been examined in depth so far. We hypothesized that abnormal patterning and/or size of the thoracic veins could occur in rats with CDH. This hypothesis was tested by microscopic magnetic resonance imaging (MMRI), a high-resolution tool able to detect subtle changes of vessels in small animals.

MATERIAL/METHODS

Fetuses from pregnant rats fed either 100 mg i.g. nitrofen or vehicle on E9.5 were recovered near term. A 7 T MMRI system with a coronal multislice fast spin echo sequence allowed diagnosis of CDH (n = 19), and T2 SE high-resolution sequences made assessment of the pattern and width of cervico-thoracic veins possible. Values were corrected for body size by dividing them by the length of thoracic vertebrae T3-T5. The results in nitrofen and control (n = 11) groups were compared by non-parametric tests (*p < 0.05).

RESULTS

Congenital diaphragmatic hernia fetuses were smaller than controls (4.5 ± 0.26 vs. 5.3 ± 0.2 g*). The widths (corrected for body size) of left external, both innominate, right superior vena cava and azygos veins were significantly smaller in CDH rats than in controls.

CONCLUSIONS

The cervico-thoracic veins are normally patterned but abnormally narrow (except the internal jugulars) in rats with CDH. The same embryonic NC dysregulation that accounts for cardiovascular malformations could also explain these venous anomalies in CDH.

Microscopic magnetic resonance in congenital diaphragmatic hernia and associated malformations in rats

BACKGROUND/AIM

The research on congenital diaphragmatic hernia (CDH) is often carried out on the nitrofen fetal rat model in which most investigations involve microdissections and fastidious assessment of serial sections of different anatomic areas. Current microscopic magnetic resonance (MMR) equipment allows detailed anatomic studies of alive, fresh or fixed fetuses. The purpose of the present study was to demonstrate that CDH itself and most of the associated malformations are adequately imaged and measured by MMR.

MATERIALS AND METHODS

Fetuses from pregnant rats treated with either i.g. vehicle (control, n = 10) or 100 mg nitrofen (only those with CDH, n = 18) on E9.5 were recovered on E21 (term = E22) and total body was scanned by MMR under sedation in a 7 T MRI system (Bruker Medical, Ettlingen, Germany). CDH was detected with a coronal multislice fast spin echo sequence with a long repetition time and short effective echo time. Oblique MPR and 3D reconstructions were used. All studies were processed with attention to the hernia and its contents and the structure of the tracheobronchial tree and the lung, the heart and great vessels, the thymus and cervico-thoracic vertebrae. The findings in both groups were compared.

RESULTS

Congenital diaphragmatic hernia, lung hypoplasia and parenchymal features were clearly depicted. Tracheal ring anomalies were also demonstrated. The thymus was significantly smaller in CDH pups (2.9 x 1 x 2.4 mm) than in controls (4 x 1.3 x 2.8 mm) (p < 0.01). MRI was particularly performant for imaging cardiovascular anomalies: 4 double aortic arches, 3 Fallots, 3 right aortic arches, 3 ventricular septal defects and 1 aberrant subclavian artery.

CONCLUSIONS

Microscopic magnetic resonance involves refined and expensive equipment but it provides a powerful research tool for the study of CDH and other malformations in rat fetuses. Further work on this area is warranted.

Right congenital diaphragmatic hernia associated with anorectal malformation

We describe a neonate in whom a right congenital diaphragmatic hernia and an anorectal malformation coexisted. Their coexistence in the same patient is rare.

Imaging of congenital diaphragmatic hernias

Congenital diaphragmatic hernias are complex and life-threatening lesions that are not just anatomic defects of the diaphragm, but represent a complex set of physiologic derangements of the lung, the pulmonary vasculature, and related structures. Imaging plays an increasingly important role in the care of these infants. Prenatal sonography and MRI have allowed early and accurate identification of the defect and associated anomalies. These tools have also been the key to defining the degree of pulmonary hypoplasia and to predicting neonatal survival and need for aggressive respiratory rescue strategies. In the postnatal period, conventional radiography supplemented by cross-sectional imaging in selected cases can be very useful in sorting out the differential diagnosis of intrathoracic masses, in the detection of associated anomalies, and in the management of complications. Understanding the pathogenesis of diaphragmatic defects, the underlying physiologic disturbances, and the strengths and limitations of current imaging protocols is essential to the effective and accurate management of these complex patients.

Genetic aspects of human congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common major malformation affecting 1/3000-1/4000 births, which continues to be associated with significant perinatal mortality. Much current research is focused on elucidating the genetics and pathophysiology contributing to CDH to develop more effective therapies. The latest data suggest that many cases of CDH are genetically determined and also indicate that CDH is etiologically heterogeneous. The present review will provide a brief summary of diaphragm development and model organism work most relevant to human CDH and will primarily describe important human phenotypes associated with CDH and also provide recommendations for diagnostic evaluation of a fetus or infant with CDH.

Downregulation of GATA4 and GATA6 in the heart of rats with nitrofen-induced diaphragmatic hernia

PURPOSE

The high incidence of cardiac malformations in humans and animal models with congenital diaphragmatic hernia (CDH) is well known. The precise molecular mechanisms underlying cardiac maldevelopment in CDH are still unclear. It has been reported that GATA4 and GATA6, members of the GATA transcription factor family, act cooperatively to regulate cardiovascular development, and the levels of cardiac GATA4 and GATA6 are important regulators of cardiomyocyte proliferation, cardiac morphogenesis, and embryo survival. In addition, the GATA4/GATA6 double heterozygous mutant embryo model displayed a spectrum of cardiovascular malformations similar to those seen in human CDH and nitrofen-induced animal models, including ventricular and aortopulmonary septal defects and thin ventricular myocardium. To test the hypothesis that expression of GATA4 and GATA6 is reduced in early stages of gestation in a CDH hypoplastic heart, we investigated the expression of GATA4 and GATA6 in the hearts of nitrofen-treated rats in early gestation. Wnt2, bone morphogenetic protein 4 (BMP4), and myocyte enhancer factor 2C (MEF2C) were also investigated as GATA4/6 target genes involved in cardiogenesis.

MATERIALS AND METHODS

Fetal rat hearts of normal (n = 7) and nitrofen-treated (n = 7) dams were harvested on embryonic day 13. The expression of GATA4, GATA6, Wnt2, BMP4, and MEF2C was analyzed in each heart by real-time reverse transcription-polymerase reaction.

RESULTS

The gene expression of GATA4, GATA6, Wnt2, BMP4, and MEF2C on embryonic day 13 were significantly reduced (P < .05) in the hearts of nitrofen-treated animals compared with normal hearts of equivalent age.

CONCLUSION

Decreased expression of GATA4 and GATA6 and their target genes in the developing fetal heart may perturb the delicate regulation of cardiovascular development, resulting in cardiovascular malformations in the nitrofen rat model.

Massive pericardial effusion in an early gestational fetus having intrapericardial diaphragmatic hernia

Intrapericardial diaphragmatic hernia is a very rare phenotype of congenital diaphragmatic hernia. Twelve cases of this condition have been reported under the age of 1 year since 1981, and in only four cases were abnormal findings observed antenatally. We report a case of a fetus with this disease in which pericardial effusion was noted in an earlier gestational age than any other previously reported cases. A 35-year-old pregnant woman was referred to our center at 16 weeks' gestation. Ultrasound revealed that the bilateral lungs of the fetus were very small due to the compression by massive pericardial effusion. Pregnancy was terminated at 18 weeks, and autopsy of the stillborn baby revealed intrapericardial diaphragmatic hernia and cardiac aneurysm of the right ventricle. In conclusion, when pericardial effusion is observed in a fetus, intrapericardial diaphragmatic hernia, a very rare type of congenital diaphragmatic hernia, must be included in a differential diagnosis.

Congenital diaphragmatic hernia and associated cardiovascular malformations: type, frequency, and impact on management

The co-occurrence of congenital diaphragmatic hernia (CDH) and cardiovascular malformations (CVMs) has important clinical, genetic, and developmental implications. Previous examinations of this topic often included patients with genetic syndromes. To correct this potential bias, we undertook an extensive review of the literature and obtained new data. The frequency of CVMs associated with isolated CDH was 11-15%. A careful analysis of CVMs indicates that atrial and ventricular septal defects, conotruncal defects, and left ventricular outflow tract obstructive defects were the most common type of CVMs, but proportional to the frequency of occurrence in the general population. The combination of CVM and CDH results in a poorer prognosis than would be expected with either malformation alone. However, the impact on survival from patients with a genetic syndrome has not been consistently evaluated. We encourage researchers to re-analyze existing series and recommend that future studies distinguish isolated CDH from that which is associated with other malformations, especially as part of genetic syndromes. Therapies should be tailored to maximize cardiac output and systemic oxygen delivery rather than systemic oxygen saturation alone. Although there is speculation about the frequency with which isolated left ventricular "hypoplasia" occurs in patients with CDH, we suggest it results from compression of a pre-load deficient left ventricle by the hypertensive right ventricle, and unlike true hypoplasia, is reversible. Irrespective of the type of severity of CVMs in patients with CDH, the degree of pulmonary hypoplasia and pulmonary vascular disease predicts outcome.

Vitamin A deficiency (VAD), teratogenic, and surgical models of congenital diaphragmatic hernia (CDH)

Congenital diaphragmatic hernia (CDH) is a congenital malformation that occurs with a frequency of 0.08 to 0.45 per 1,000 births. Children with CDH are born with the abdominal contents herniated through the diaphragm and exhibit an associated pulmonary hypoplasia which is frequently accompanied by severe morbidity and mortality. Although the etiology of CDH is largely unknown, considerable progress has been made in understanding its molecular mechanisms through the usage of genetic, teratogenic, and surgical models. The following review focuses on the teratogenic and surgical models of CDH and the possible molecular mechanisms of nitrofen (a diphenyl ether, formerly used as an herbicide) in both induction of CDH and pulmonary hypoplasia. In addition, the mechanisms of other compounds including several anti-inflammatory agents that have been linked to CDH will be discussed. Furthermore, this review will also explore the importance of vitamin A in lung and diaphragm development and the possible mechanisms of teratogen interference in vitamin A homeostasis. Continued exploration of these models will bring forth a clearer understanding of CDH and its molecular underpinnings, which will ultimately facilitate development of therapeutic strategies.

Stephen L. Gans Distinguished Overseas Lecture. The neural crest in pediatric surgery

AIM

This review highlights the relevance of the neural crest (NC) as a developmental control mechanism involved in several pediatric surgical conditions and the investigative interest of following some of its known signaling pathways.

METHODS

The participation of the NC in facial clefts, ear defects, branchial fistulae and cysts, heart outflow tract and aortic arch anomalies, pigmentary disorders, abnormal enteric innervation, neural tumors, hemangiomas, and vascular anomalies is briefly reviewed. Then, the literature on clinical and experimental esophageal atresia-tracheoesophageal fistula (EA-TEF) and congenital diaphragmatic hernia (CDH) is reviewed for the presence of associated NC defects. Finally, some of the molecular signaling pathways involved in both conditions (sonic hedgehog, Hox genes, and retinoids) are summarized.

RESULTS

The association of facial, cardiovascular, thymic, parathyroid, and C-cell defects together with anomalies of extrinsic and intrinsic esophageal innervation in babies and/or animals with both EA-TEF and CDH strongly supports the hypothesis that NC is involved in the pathogenesis of these malformative clusters. On the other hand, both EA-TEF and CDH are observed in mice mutant for genes involved in the previously mentioned signaling pathways.

CONCLUSIONS

The investigation of NC-related molecular pathogenic pathways involved in malformative associations like EA-TEF and CDH that are induced by chromosomal anomalies, chemical teratogens, and engineered mutations is a promising way of clarifying why and how some pediatric surgical conditions occur. Pediatric surgeons should be actively involved in these investigations.

Overview of epidemiology, genetics, birth defects, and chromosome abnormalities associated with CDH

Congenital diaphragmatic hernia (CDH) is a common and well-studied birth defect. The etiology of most cases remains unknown but increasing evidence points to genetic causation. The data supporting genetic etiologies which are detailed below include the association of CDH with recurring chromosome abnormalities, the existence of CDH-multiplex families, and the co-occurrence of CDH with additional congenital malformations.

Genetic factors in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a relatively common birth defect associated with high mortality and morbidity. Although the exact etiology of most cases of CDH remains unknown, there is a growing body of evidence that genetic factors play an important role in the development of CDH. In this review, we examine key findings that are likely to form the basis for future research in this field. Specific topics include a short overview of normal and abnormal diaphragm development, a discussion of syndromic forms of CDH, a detailed review of chromosomal regions recurrently altered in CDH, a description of the retinoid hypothesis of CDH, and evidence of the roles of specific genes in the development of CDH.

Impaired mesenchymal cell function in Gata4 mutant mice leads to diaphragmatic hernias and primary lung defects

Congenital diaphragmatic hernia (CDH) is an often fatal birth defect that is commonly associated with pulmonary hypoplasia and cardiac malformations. Some investigators hypothesize that this constellation of defects results from genetic or environmental triggers that disrupt mesenchymal cell function in not only the primordial diaphragm but also the thoracic organs. The alternative hypothesis is that the displacement of the abdominal viscera in the chest secondarily perturbs the development of the heart and lungs. Recently, loss-of-function mutations in the gene encoding FOG-2, a transcriptional co-regulator, have been linked to CDH and pulmonary hypoplasia in humans and mice. Here we show that mutagenesis of the gene for GATA-4, a transcription factor known to functionally interact with FOG-2, predisposes inbred mice to a similar set of birth defects. Analysis of wild-type mouse embryos demonstrated co-expression of Gata4 and Fog2 in mesenchymal cells of the developing diaphragm, lungs, and heart. A significant fraction of C57Bl/6 mice heterozygous for a Gata4 deletion mutation died within 1 day of birth. Developmental defects in the heterozygotes included midline diaphragmatic hernias, dilated distal airways, and cardiac malformations. Heterozygotes had any combination of these defects or none. In chimeric mice, Gata4(-/-) cells retained the capacity to contribute to cells in the diaphragmatic central tendon and lung mesenchyme, indicating that GATA-4 is not required for differentiation of these lineages. We conclude that GATA-4, like its co-regulator FOG-2, is required for proper mesenchymal cell function in the developing diaphragm, lungs, and heart.

Molecular genetics of congenital diaphragmatic defects

Congenital diaphragmatic hernia (CDH) is a severe birth defect that is accompanied by malformations of the lung, heart, testis, and other organs. Patients with CDH may have any combination of these extradiaphragmatic defects, suggesting that CDH is often a manifestation of a global embryopathy. This review highlights recent advances in human and mouse genetics that have led to the identification of genes involved in CDH. These include genes for transcription factors, molecules involved in cell migration, and extracellular matrix components. The expression patterns of these genes in the developing embryo suggest that mesenchymal cell function is compromised in the diaphragm and other affected organs in patients with CDH. We discuss potential mechanisms underlying the seemingly random combination of diaphragmatic, pulmonary, cardiovascular, and gonadal defects in these patients.

Cardiovascular malformations in Fryns syndrome: is there a pathogenic role for neural crest cells?

We performed a comprehensive literature and case report review to characterize the cardiovascular malformations (CVMs) associated with Fryns syndrome (OMIM #229850), a multiple congenital anomaly/mental retardation syndrome consisting of diaphragmatic defects, significant pulmonary hypoplasia, distinctive facial appearance, distal digital hypoplasia, and numerous other external and internal anomalies. A total of 112 patients meeting diagnostic guidelines for Fryns syndrome were identified, of whom 82 met narrowly defined criteria (Group I) and 30 met broader diagnostic criteria (Group II). Twelve patients reported as having Fryns syndrome with atypical features (Group III) were also analyzed. A CVM was reported in 51% (42 of 82) of Group I patients, most commonly an atrial or ventricular septal defect (VSD) (23 of 42, 55%). Conotruncal and aortic arch CVMs were common (11 of 42, 26%), but not significantly so compared to the general population of infants to age 1 year [Ferencz et al., 1997]. Recognizing that minor septal defects associated with congenital diaphragmatic hernia (CDH) may occur in response to altered hemodynamics (instead of being a bonafide CVM), we excluded four patients reported as having hemodynamically insignificant VSDs. Following these exclusions, conotruncal CVMs were found more commonly than in the general population (11 of 38, 29%, P < or = 0.025). In Group II, 9 of 30 (30%) had a CVM with no predominant type among the small number of cases reviewed. Among the atypical Fryns syndrome patients in Group III, half (6 of 12, 50%) had a CVM; most (4 of 6, 67%) were conotruncal, in particular, type B interrupted aortic arch (3 of 4). Patients with Fryns syndrome have a high rate of CVMs, warranting thorough cardiac evaluation including echocardiogram (fetal and/or postnatal) in all patients, similar to the evaluation for other patients with diaphragmatic hernia. The possible association between conotruncal CVMs and Fryns syndrome may provide additional support for an etiologic role of genes related to neural crest cell development in the pathogenesis of Fryns syndrome and hence, congenital diaphragmatic hernia.

Right congenital diaphragmatic hernia associated with a complex heart disease

A case of right diaphragmatic hernia is presented associated with a complex congenital heart disease (double-outlet right ventricle, transposition of the great arteries and left isomerism) diagnosed prenatally. Despite high-frequency oscillatory ventilation plus nitric oxide and uneventful repair of the hernia, the infant died after 6 days of uncontrolled pulmonary hypertension and severe aortic coarctation that developed postnatally.

Effects of antioxidant vitamins on molecular regulators involved in lung hypoplasia induced by nitrofen

INTRODUCTION

Oxidant herbicide nitrofen (2,4-dichloro-4'-nitrodiphenyl ether) induces in rat embryos congenital diaphragmatic hernia (CDH) with lung hypoplasia. The present study aims at examining whether antioxidant vitamins A, E, and C reverse the effects of the teratogen in the lungs of exposed rats and how they modify the expression of molecular regulators known to be involved in their pathogenesis.

MATERIALS AND METHODS

Wet lung weight-body weight ratio, total DNA, and total protein were determined. Thyroid transcription factor 1 (TTF-1), hepatocyte nuclear factor 3beta (HNF-3beta), and surfactant protein B (SP-B) proteins were measured by immunoblot assay in lung homogenates from rat fetuses exposed in utero to either nitrofen 100 mg intragastrically or vehicle. The coexpression of these factors in the alveolar epithelium was demonstrated by immunohistochemistry. The effects of the addition of vitamins A, C, and E were assessed by comparison with analysis of variance.

RESULTS

Nitrofen decreased lung weight, total DNA, and total protein. The addition of antioxidant vitamins had no effect on lung weight, but increased DNA and protein contents. TTF-1, HNF-3beta, and SP-B proteins were decreased in lung homogenates of exposed rats with CDH. The addition of antioxidant vitamins nearly normalized these values.

CONCLUSIONS

The effects of nitrofen in fetal rat lungs are reversed in part by antioxidant vitamins by upregulating the expression of TTF-1, HNF-3beta, and SP-B. This approach could help to develop transplacental prenatal interventions for CDH.

A population-based study of congenital diaphragmatic hernia outcome in New South Wales and the Australian Capital Territory, Australia, 1992-2001

PURPOSE

The aim of the study was to describe the incidence and survival of infants born with congenital diaphragmatic hernia (CDH) in the state of New South Wales (NSW) and the Australian Capital Territory (ACT), Australia.

METHODS

A population-based cohort study of all infants inclusive up to 1 month of age diagnosed with CDH in NSW and the ACT between 1992 and 2001 was conducted. Data sources were the NSW and ACT Neonatal Intensive Care Data Collection (Neonatal Intensive Care Units Study), NSW Birth Defects Register, Population Health Research Centre of ACT Health, and NSW Midwives Data Collection. Individual risk factors for mortality were assessed using the chi(2) test with P < .05 being considered statistically significant. Multivariate analysis was performed using logistic regression to adjust for potential confounding variables.

RESULTS

From the databases used, the incidence of CDH in NSW and the ACT was 1 per 3800 births. Of 242 infants identified with CDH, 8% underwent termination of pregnancy, 10% were stillborn after 20 weeks' gestation, and 82% were liveborn. Most liveborn infants (70%) were delivered at term with a 64% survival, whereas 30% were preterm with a 35% survival. For liveborn infants, the overall preoperative mortality was 35% with 56% surviving to discharge. Logistic regression identified a low 5-minute Apgar score, prematurity, and air leak as independent risk factors for mortality.

CONCLUSIONS

This population-based study of CDH provides us with baseline data for our states. Mortality is high in preterm infants and in the preoperative period. Avoiding preterm delivery and improving preoperative stabilization are the measures most likely to improve survival.

Vitamin A improves Pax3 expression that is decreased in the heart of rats with experimental diaphragmatic hernia

BACKGROUND/AIMS

Rats with nitrofen-induced congenital diaphragmatic hernia (CDH) have hypoplasia and malformations of the heart. The mechanism of action of nitrofen involves changes in neural crest signaling. Pax3 function is required for cardiac neural crest cells to complete their migration to the developing heart. Vitamin A improves heart hypoplasia. The aims of this study were to examine whether Pax3 expression is decreased in the heart of E13 E15 and E21 rats exposed to nitrofen and if vitamin A reverts this effect.

MATERIAL AND METHODS

Pregnant rats received either 100 mg nitrofen or olive oil on E9.5. Each group was divided into 2 subgroups according to the subsequent treatment with intragastric vitamin A (15000 IU) or vehicle on E10.5 to E11.5. The pups were recovered on E13, E15 and E21 and the hearts were dissected out. Pax3 mRNA expression was determined by quantitative real time PCR. Comparisons among groups were made with ANOVA and Bonferroni post hoc tests with a threshold of significance of P < .05.

RESULTS

Pax3 mRNA expression was significantly decreased on E13 and E15 in the hearts of nitrofen-treated embryos and it remained decreased although not significantly on E21. Vitamin A recovered this expression on E13, partially on E15 and above normal levels on E21.

CONCLUSIONS

Pax3 is underexpressed in the hearts of nitrofen exposed embryonal rats on days 13th and 15th of gestation and tends to be lower than normal near term. Vitamin A up-regulates this expression on the 3 end points. The mechanism of action of Pax3 should be further investigated because it could be one of the targets for future prenatal transplacental intervention.

Expression of Connexin 43 in the hearts of rat embryos exposed to nitrofen and effects of vitamin A on it

Rats with experimental congenital diaphragmatic hernia (CDH) have heart hypoplasia and conotruncal and great vessel malformations that are likely related to disturbed neural crest developmental control. Neural crest cells communicate through intercellular gap junctions whose main protein is Connexin 43 (Cx43). The migration and participation of neural crest cells in heart development is likely influenced by this protein which might be also directly involved in myocardial development. Vitamin A is beneficial for heart hypoplasia in CDH rats. The aims of this study were to examine the status of Cx43 in the heart of embryonal rats exposed to nitrofen and to assess if vitamin A reverts these effects. Pregnant rats received either 100 mg nitrofen or olive oil on E9.5. Each group was divided into two subgroups according to the subsequent treatment with intragastric vitamin A (15,000 i.u.) or vehicle on E10.5 and E11.5. The pups were recovered on E13, E15, and E21 and the hearts were dissected out and pooled. Cx43 mRNA expression was determined by quantitative real-time PCR. Comparisons among groups were made with ANOVA and Bonferroni post hoc tests with a threshold of significance of P<0.05. In control rats Cx43 mRNA was minimally expressed on E13 and E15 and fully expressed on E21. Nitrofen significantly increased Cx43 mRNA on E15. Additional treatment with vitamin A tended to moderate this increase on E15. Cx43 was overexpressed in the hearts of nitrofen-exposed embryonal rats on day E15 of gestation. Vitamin A tended to normalize this expression. The mechanism of action of Cx43 deserves further investigation.

Effects of prenatal vitamins A, E, and C on the hypoplastic hearts of fetal rats with diaphragmatic hernia

BACKGROUND/AIM

Nitrofen induces heart hypoplasia together with congenital diaphragmatic hernia (CDH) in rats. Intracellular oxidative stress might be one of the mechanisms of action of the teratogen, and vitamin A has been shown to reverse in part these effects when administered simultaneously or shortly after it. This study aims at testing the hypothesis that vitamin A and other antioxidant vitamins, such as E and C, could improve myocardial development even when administered late in gestation, a likely useful period for prenatal medication.

MATERIAL AND METHODS

Time-mated Sprague-Dawley female rats were exposed to either vehicle (control) or 100 mg of nitrofen (experimental) on day 9.5 of gestation. In 3 additional groups, the animals were exposed to vitamin A (total 15000 IU), vitamin E (total 150 IU), or vitamin C (total 150 IU) on days 16, 17, and 18. The fetuses were recovered on day 21, and randomly selected hearts of those with CDH were processed for histologic studies (hematoxylin-eosin and periodic acid-Schiff stainings), DNA and protein contents, and ki-67 (proliferation) and terminal deoxynucleotidyl transferase-mediated dUTP-biotin end labeling (apoptosis) studies. The differences among groups were assessed by analysis of variance with Bonferroni/Dunn post hoc tests and a threshold of significance of P < .05.

RESULTS

Nitrofen induced heart hypoplasia in terms of decreased heart/body weight, cell mass (less DNA and protein), and proportion of proliferating cells with increased apoptosis. Vitamin C alleviated weight hypoplasia and the 3 vitamins were able to restore cell mass and to reestablish near-normal figures of proliferation and apoptosis.

CONCLUSIONS

Antioxidant vitamins A, E, and C given late in gestation alleviate heart hypoplasia that accompanies CDH in the rat model. This timing suggests that the beneficial effects are exerted on the maturational phase of development.

Comparison of developmental toxicity of selective and non-selective cyclooxygenase-2 inhibitors in CRL:(WI)WUBR Wistar rats – DFU and piroxicam study

BACKGROUND

Cyclooxygenase (COX) inhibitors are one of the most often ingested drugs during pregnancy. Unlike general toxicity data, their prenatal toxic effects were not extensively studied before. The aim of the experiment was to evaluate the developmental toxicity of the non-selective (piroxicam) and selective (DFU; 5,5-dimethyl-3-(3-fluorophenyl)-4-(4-methylsulphonyl) phenyl-2(5H)-furanon) COX-2 inhibitors.

METHODS

Drugs were separately, orally once daily dosed to pregnant rats from day 8 to 21 (GD1=plug day). Doses were set at 0.3, 3.0 and 30.0mg/kg for piroxicam and 0.2, 2.0 and 20.0mg/kg for DFU. Fetuses were delivered on GD 21 and routinely examined. Comprehensive clinical and developmental measurements were done. The pooled statistical analysis for ventricular septal (VSD) and midline (MD) defects was performed for rat fetuses exposed to piroxicam, selective and non-selective COX-2 inhibitor based on present and historic data.

RESULTS

Maternal toxicity, intrauterine growth retardation, and increase of external and skeletal variations were found in rats treated with the highest dose of piroxicam. Decrease of fetal length was the only signs of the DFU developmental toxicity observed in pups exposed to the highest compound dose. Lack of teratogenicity was found in piroxicam and DFU-exposed groups. Prenatal exposure to non-selective COX inhibitors increases the risk of VSD and MD when compared to historic control but not with selective COX-2 inhibitors.

CONCLUSION

Both selective and non-selective COX-2 inhibitors were toxic for rats fetuses when administered in the highest dose. Unlike DFU, piroxicam was also highly toxic to the dams. Prenatal exposure to selective COX-2 inhibitors does not increase the risk of ventricular septal and midline defects in rat when compared to non-selective drugs and historic control.

The genetics of congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a common birth defect with a high mortality and morbidity. A clear understanding of the pathogenesis of CDH is critical for determining prognosis and planning treatment, but to date, information on the genetic etiology of both nonsyndromic and syndromic CDH is limited. This paper summarizes the current knowledge concerning the genes, syndromes, and chromosome aberrations associated with CDH in humans and in animal model systems. Mutations in several different genes have been described in syndromic CDH, but there is only one mutation that has been reported in non-syndromic CDH to date. However, animal models suggest that genes involved in cell migration, myogenesis, and connective tissue formation are critical to normal diaphragm formation, and these data provide a starting point for the search for other genes involved in the pathogenesis of CDH.

Altered expression of angiotensin II receptor subtypes and transforming growth factor-beta in the heart of nitrofen-induced diaphragmatic hernia in rats

The renin-angitensin system (RAS) plays an important role as a growth factor in cardiac development. Angiotensin converting enzyme is involved in converting angiotensin I to angiotensin II (Ag-II). The effects of Ag-II are mediated by two primary receptors, type 1 (AT1) and type 2 (AT2). Ag-II stimulates transforming growth factor-beta1(TGF-beta1) and acts as a potent stimulant of myocyte growth and fetal contractile protein gene transcription. The aim of this study was to determine the expression of Ag-II receptor subtypes and TGF-beta1 in the hypoplastic heart of nitrofen-induced congenital diaphragmatic hernia (CDH). CDH was induced in pregnant rats following administration of 100 mg nitrofen on day 9.5. The fetuses were divided into three groups: normal controls (n=16), nitrofen-treated without CDH (n=16), and nitrofen-induced CDH (n=16). Reverse transcriptase-polymerase chain reaction was performed to evaluate mRNA expression of AT1, AT2, and TGF-beta1. Levels of mRNA were expressed as a ratio of the band density divided by that of beta-actin. AT1 and AT2 mRNA expressions were significantly decreased in CDH heart compared with controls (0.43+/-0.33 vs. 1.0+/-0.48 and 0.62+/-0.23 vs. 1.4+/-0.43, respectively). TGF-beta1 mRNA expressions were also significantly decreased in CDH heart compared with controls (0.38+/-0.17 vs. 0.72+/-0.26). No significant difference was found between the hearts of controls and nitrofen-treated rats without CDH. The decreased expression of AT1, AT2, and TGF-beta1 mRNA in the hypoplastic heart suggests that the downregulation of RAS may be involved in the pathogenesis of cardiac hypoplasia in nitrofen-induced CDH.

Pax3 mRNA is decreased in the hearts of rats with experimental diaphragmatic hernia

Rats with nitrofen-induced congenital diaphragmatic hernia (CDH) have heart hypoplasia and cardiovascular malformations. The mechanism of action of nitrofen involves changes in neural crest signaling. Pax3 function is required for cardiac neural crest cells to complete their migration to the developing heart. The aim of this study was to examine whether Pa x 3 expression is changed at two gestational endpoints in rat embryos or fetuses exposed to nitrofen. On day E9.5 of gestation, pregnant rats received either 100 mg of nitrofen (n=10) or vehicle alone (control, n=10). The fetuses were recovered on E15 or E21. Their hearts were dissected out and weighed. Pax3 mRNA expression was determined by real-time polymerase chain reaction. We used two-tailed Student's t-tests to compare groups, with a threshold of significance of p<0.05. Compared with controls, nitrofen-exposed fetuses had heart hypoplasia in terms of heart/body weight ratio (0.62+/-0.10% vs. 0.77+/-0.17%, p<0.05). Pax3 mRNA expression in the heart was significantly decreased on E15 in nitrofen-treated embryos (32.94+/-17.11 U vs. 55.09+/-11.56 U, p<0.05), and it was still decreased, although not significantly, in the hearts of nitrofen-exposed fetuses recovered on E21 (15.67+/-5.56 U vs. 20.51+/-5.92 U, not significant). In conclusion, Pax3 is underexpressed in the hearts of nitrofen-exposed embryonal rats before the end of gestation. The mechanism of action of Pax3 should be further investigated because it could be one of the targets for future prenatal transplacental intervention.

Fryns syndrome with Hirschsprung disease: Support for possible neural crest involvement

Fryns syndrome is an autosomal recessive multiple congenital anomaly/mental retardation syndrome characterized by coarse face, distal limb hypoplasia, and diaphragmatic anomalies. We describe a newborn girl with Fryns syndrome and Hirschsprung disease, an association that has been reported in five previous cases. These patients support the hypothesis that the neural crest plays a role in the pathogenesis of Fryns syndrome. Clinically asymptomatic or subtle anomalies that are in the spectrum of neural crest maldevelopment should be sought in all patients with Fryns syndrome including stillbirths, neonatal deaths, as well as long-term survivors. We suspect that the clinical observation about Hirschsprung disease and Fryns syndrome may provide insight into its molecular mechanisms and candidate genes.

Bilateral congenital diaphragmatic hernia with absent pleura and pericardium

BACKGROUND

Bilateral congenital diaphragmatic hernia is a rare form of diaphragmatic hernia. Independently, pericardial defects are an extremely rare phenomenon. In the case presented, we provide the first complete description of an infant with bilateral congenital diaphragmatic hernia with complete agenesis of the pericardium and inferior parietal pleura.

CASE

A male infant was born at 38 weeks of gestation with a prenatal diagnosis of left-sided congenital diaphragmatic hernia. After 1 week of aggressive management, the patient was taken to the operating room for repair. Intraoperatively, the patient was found to have absence of the diaphragm bilaterally, no pleura inferiorly, and no pericardium. A biological mesh was used to construct a diaphragm. At 6 months of age, the patient is growing normally, requiring only supplemental oxygen without pressure support.

CONCLUSIONS

Embryologically, this anomaly represents complete lack of development of the pleurocardial folds, pleuroperitoneal folds, and transverse septum, which is previously unreported.

Postmortem findings and clinicopathological correlation in congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a severe life-threatening disease, with an incidence of 3 per 10,000 births, that can occur as an isolated defect or in combination with other congenital anomalies. We reviewed the clinical and autopsy reports of 39 subjects with CDH that were autopsied between 1988 and 2001 to determine whether autopsy had an additional value in the detection of malformations in patients with CDH. We compared the clinical data (including echographic results in some patients) concerning congenital anomalies with the autopsy results. Before autopsy, 6 structural cardiac defects, 3 anomalies of the urogenital system, and 3 anomalies of the digestive tract were observed in 10 patients (clinical and echographic results). However, with postmortem examination, only 4 structural cardiac defects were confirmed, 2 cases showed another cardiac anomaly, and 7 new cardiac defects were found. In the urogenital system, 1 anomaly was confirmed, 1 was not confirmed, and 1 showed another malformation. In addition, in 7 patients new urogenital malformations were found after autopsy. In the digestive tract, all 3 malformations were confirmed, but we found 3 new malformations after postmortem examination. All clinically established dysmorphic features and anomalies of the skeletal system and central nervous system were confirmed by autopsy, and no additional malformations were found. We concluded that postmortem examination has an important additional role in the detection of structural cardiac defects and malformations of the urogenital system and digestive tract in children with CDH.

The vagus and recurrent laryngeal nerves in experimental congenital diaphragmatic hernia

BACKGROUND

The etiology of the anatomic and functional abnormalities of the esophagus in infants surviving congenital diaphragmatic hernia (CDH) remains unclear. We showed previously that fetal rats with CDH have malformations of neural crest-derived structures. The aim of this study was to examine the anatomy of the vagus and the recurrent laryngeal nerves, both of neural crest origin, in rats with CDH.

METHODS

We used the nitrofen-induced CDH fetal rat model. Nine control fetuses from four dams and nine fetuses with CDH from seven dams were included in this study. Embryos were fixed in formalin and a thoracic block from the larynx to tracheal bifurcation was serially sectioned in the horizontal plane. One in every ten sections was stained with hematoxylin and eosin. The image was digitalized using biological software (TDR-3dbase). Vagus and recurrent laryngeal nerves, trachea, esophagus and the great vessels were examined. In order to obtain the three-dimensional reconstructions, 90-120 consecutive images were used.

RESULTS

In comparison with controls there were striking abnormalities of the vagus and the recurrent laryngeal nerves in fetuses with CDH: (1) absence of the left (2/9) or right (2/9) vagus nerves; (2) absence of the left (3/9) or right (3/9) recurrent laryngeal nerves; (3) marked hypoplasia of the trunk of the vagus (2/9); (4) deviations of their normal course and change of normal anatomical relationships into the mediastinum (2/9); and (5) abnormal branching of the lower portion of the vagus (1/9).

CONCLUSIONS

Rat fetuses with CDH have anomalies of the vagus and recurrent laryngeal nerves that support the concept of a neural crest involvement in the origin of this malformation. 3-D reconstructions allow a detailed analysis and provide a precise insight into the real anatomy. These observations may explain esophageal motility disorders in CDH.

Fetal heart development in the nitrofen-induced CDH rat model: the role of mechanical and nonmechanical factors

BACKGROUND/PURPOSE

In congenital diaphragmatic hernia (CDH), it was recently shown that early and late gestational lung underdevelopment is caused by nonmechanical and mechanical factors, respectively. Heart underdevelopment, which might predict lung hypoplasia, is commonly attributed to mechanical factors. The authors analyzed whether nonmechanical and mechanical factors affect cardiac growth and correlations between lung and heart weights during gestation.

METHODS

Left-sided CDH was induced in pregnant Wistar rats by administration of nitrofen on E9.5. At selected gestational ages (E18, E20, and E22), the lungs and heart were harvested, weighed, and analyzed for DNA and protein contents. Left lung and heart weights were correlated at those gestational ages. Two experimental groups: nitrofen without CDH (nitrofen), and nitrofen with CDH (CDH), were compared with normal controls.

RESULTS

At E18, both nitrofen-exposed groups presented similar and significant left lung (LL) hypoplasia. As gestation progressed (E20 and E22), in the nitrofen group left lung (LL) hypoplasia decreased, whereas in the CDH group LL hypoplasia was exacerbated relative to normal controls. In contrast, at E18 and E20, heart-to-body weight ratios as well as cardiac DNA and protein contents were reduced significantly in all animals exposed to nitrofen, with no significant differences observed between nitrofen and CDH groups. As gestation progressed, the difference between cardiac parameters in nitrofen-exposed and normal control rats diminished, and at E22 no significant differences were documented. In the CDH group, significant correlations were seen between lung and heart weights at E18 (r = 0.65; P <.05) and E20 (r = 0.4; P <.05), whereas at term gestation (E22) no significant correlation was observed (r = 0.21, not significant).

CONCLUSIONS

Nonmechanical factors, which might be directed by nitrofen, play a role in the pathogenesis of lung and heart hypoplasia manifested precociously in fetal life, whereas mechanical compression might influence only lung growth during late gestation. Heart weight predicts lung weight only in early gestational ages.

The adrenal cortex in experimental congenital diaphragmatic hernia

BACKGROUND/PURPOSE

Adrenal cortical malfunction was found recently in patients with severe congenital diaphragmatic hernia (CDH). The current study tests the hypothesis that the development and function of the adrenal cortex could be abnormal in an experimental model of CDH.

METHODS

Pregnant rats were exposed on day 9.5 of gestation to 100 mg of 2-4-dichlorophenyl-p-nitrophenyl ether (nitrofen) diluted in olive oil. The sham group was treated only with oil. Fetuses were recovered on the 21st day, bled, and examined for the presence or absence of CDH. Adrenal glands from sham and CDH animals were dissected, weighed, and prepared for histologic, biochemical, and immunohistochemical studies (ki-67) aimed at measuring total DNA, total protein, and the proportion of proliferating cells. Serum corticosterone levels were assayed. The results in both groups were compared with parametric tests with a significance level of P <.05.

RESULTS

The adrenal weight was not different in CDH animals versus controls (0.049 +/- 0.014 v 0.052 +/- 0.012% of body weight; not significant). Total DNA was reduced significantly (1.180 +/- 0.481 v 1.909 +/- 0.893 microgram P <.05) with unchanged DNA to protein ratio. Proliferation index in both groups was 20.1 +/- 3.1% and 26.5 +/- 7.5%, respectively (not significant), and the proliferating cells were mainly located in the glomerular areas of the glands. Corticosterone levels were similar in both groups.

CONCLUSIONS

Nitrofen induces very slight changes in the development of adrenal glands of fetal rats, expressed by reduced cell proliferation especially in glomerular areas, reduced total DNA with preservation of cell sizes (constant DNA to protein ratio), with no change in function because corticosterone levels remained unchanged. It is doubtful that primary adrenal malformation/malfunction contributes to the severity of CDH in this model.

Retinal dehydrogenase-2 is inhibited by compounds that induce congenital diaphragmatic hernias in rodents

Currently, the etiology of the serious developmental anomaly congenital diaphragmatic hernia (CDH) is unknown. We have used an animal model of CDH to address this issue. We characterized four separate teratogens that produced diaphragmatic defects in embryonic rats that are similar to those in infants with CDH. We then tested the hypothesis that all these agents share the common mechanism of perturbing the retinoid-signaling pathway. Specifically, inhibition of retinal dehydrogenase-2 (RALDH2), a key enzyme necessary for the production of retinoic acid and that is expressed in the developing diaphragm, was assayed by measuring retinoic acid production in cytosolic extracts from an oligodendrocyte cell line. The following compounds all induce posterolateral defects in the rat diaphragm; nitrofen, 4-biphenyl carboxylic acid, bisdiamine, and SB-210661. Importantly, we demonstrate that they all share the common mechanism of inhibiting RALDH2. These data provide an important component of mounting evidence suggesting that the retinoid system warrants consideration in future studies of the etiology of CDH.

Congenital diaphragmatic hernia

Congenital diaphragmatic hernia (CDH) is a lethal human birth defect. Hypoplastic lung development is the leading contributor to its 30-50% mortality rate. Efforts to improve survival have focused on fetal surgery, advances in intensive care and elective delivery at specialist centres following in utero diagnosis. The impact of abnormal lung development on affected infants has stimulated research into the developmental biology of CDH. Traditionally lung hypoplasia has been viewed as a secondary consequence of in utero compression of the fetal lung. Experimental evidence is emerging for a primary defect in lung development in CDH. Culture systems are providing research tools for the study of lung hypoplasia and the investigation of the role of growth factors and signalling pathways. Similarities between the lungs of premature newborns and infants with CDH may indicate a role for antenatal corticosteroids. Further advances in postnatal therapy including permissive hypercapnia and liquid ventilation hold promise. Improvements in our basic scientific understanding of lung development may hold the key to future developments in CDH care.