Comparación de vía mediastinal posterior versus vía retroesternal para el reemplazo de esófago con ascenso gástrico parcial. Motivo de un cambio de estrategia / Comparison of posterior mediastinal versus retrosternal route for esophageal replacement with partial gastric pull-up. Rationale for a change in strategy

Introducción: existen dos rutas para realizar el reemplazo de esófago (RE), la retroesternal (RRE) y la mediastinal posterior (RMP). El objetivo del estudio es comparar los pacientes que recibieron un ascenso gástrico parcial empleando estas dos rutas. Material y métodos: Se revisaron las historias clínicas de 51 pacientes con ascenso gástrico parcial, en 27 años en el Hospital Garrahan. Se utilizó la vía RRE en 25 casos y la RMP en 26. Fueron comparados los datos epidemiológicos de los grupos y las variables para valorar la dificultad del acto quirúrgico, evolución inmediata y alejada. El estudio es comparativo, retro-prospectivo y longitudinal. Resultados: las características generales de los pacientes fueron similares. Los que recibieron el ascenso gástrico por vía RMP presentaron una menor incidencia de dehiscencia (p=0,017), de enfermedad por reflujo gastroesofágico (ERGE) (p=0,001) y de dumping (p=0,0001). No hubo diferencias estadísticamente significativas entre los dos grupos al comparar la duración del procedimiento, días de internación total y en Unidad de Cuidados Intensivos (UCI), días de permanencia en asistencia respiratoria mecánica (ARM), inicio de alimentación oral y estenosis de la anastomosis. Se observó una tendencia clínicamente relevante, que no alcanzó significancia estadística en las complicaciones intraquirúrgicas y número de dilataciones postoperatorias. No hubo necrosis del ascenso. Fallecieron 2 pacientes. Conclusiones: considerando la menor incidencia de dehiscencia, ERGE y dumping reemplazados por RMP, elegimos a ésta como nuestra primera opción para el reemplazo esofágico en la infancia (AU)

Introduction: The two routes for esophageal replacement (ER) are retrosternal (RRE) and posterior mediastinal (PMR). The aim of the study was to compare patients who received a partial gastric pull-up using either of these two routes. Material and methods: The clinical records of 51 patients who underwent partial gastric pull-up over 27 years at the Garrahan Hospital were reviewed. The RRE route was used in 25 and the RMP in 26 cases. The epidemiological data of the groups and the variables to evaluate the complexity of the surgical procedure, and shortand long-term outcome were compared. A comparative, retroprospective, and longitudinal study was conducted. Results: the general characteristics of the patients were similar. Those who underwent gastric pull-up via PMR had a lower incidence of dehiscence (p=0.017), gastroesophageal reflux disease (GERD) (p=0.001), and dumping (p=0.0001). No statistically significant differences were found between the two groups when comparing the duration of the procedure, days of total hospital and intensive care unit (ICU) stay, days on mechanical ventilation (MV), initiation of oral feeding and stenosis of the anastomosis. A clinically relevant trend, which did not reach statistical significance, was observed in intraoperative complications and number of postoperative dilatations. There was no necrosis of the pull-up. Two patients died. Conclusions: considering the lower incidence of dehiscence, GERD, and dumping associated with PMR, this was our first choice for esophageal replacement in infancy (AU)

Impaired VEGF Signaling in Lungs with Hypoplastic Esophageal Atresia and Effects on Branching Morphogenesis.

BACKGROUND/AIMS: Patients with esophageal atresia (EA) and tracheoesophageal fistula (TEF) often suffer chronic respiratory tract disease. We previously reported that primary lung maldevelopment caused by deficient branching of embryonal airways in experimental EA-TEF was induced by Adriamycin. In this study, we investigated the Vascular endothelial growth factor (VEGF) pathway in the developing lung in an EA-TEF rat model. We further analyzed the effect of recombinant VEGF treatment in vitro on branching morphogenesis of embryo lungs in experimental EA-TEF. METHODS: Pregnant rats received either Adriamycin or vehicle on E7, E8 and E9. Lungs were recovered at E15, E18 and E21. Expression of VEGF and receptors (Flk-1 and Flt-1) were assessed by quantitative PCR, immunohistochemistry and immunoblotting. E13 lungs were cultured for 72 hours with 50 ng/mL of recombinant rat VEGF in serum-free medium. The rates of increase in bud count and airway contour were evaluated. RESULTS: Our results showed a significant downregulation of VEGF during pseudoglandular and canalicular stages. In contrast, there were significantly higher levels of the Flt-1 receptor in the canalicular stage, which may represent a compensatory response to decreased VEGF. However, both variables returned to normal levels at the saccular stage. Exogenous VEGF treatment enhanced hypoplastic lung growth, evidenced by the increase in bud count and airway contour. CONCLUSIONS: A VEGF signaling defect possibly plays an important role in defective embryonic airway branching. Additionally, VEGF treatment may accelerate lung growth in EA-TEF lungs.

Diethylstilbestrol (DES): also harms the third generation.

Diethylstilbestrol(DES) is a synthet- ic nonsteroidal oestrogen and endo- crine disruptor that was used in the 1950s-1970s to prevent spontaneous abortion, despite its lack of proven efficacy. Millions of women worldwide took DES during pregnancy. In France, between 1951 and 1981, about 160 000 children were exposed to DES during the first trimester of their intrauterine life, and in some cases almost throughout the entire pregnancy. They are referred to as "DES daughters" and "DES sons". In 2010, in France, about 25 000 DES daughters were aged 33 to 40 years: pregnancies among these women are foreseeable until about 2020. In utero exposure to DES can have harmful effects. In particular, DES daughters have an increased risk of cancer and structural abnormalities of the uterus that can adversely affect their pregnancies. What are the consequences of tak- ing DES during pregnancy for the third generation, i.e. the children of DES children? To answer this question, we reviewed the available data in mid- 2016 using the standard Prescrire methodology. According to a retrospective study conducted in France by Réseau DES France, published in 2016, which included 4409 DES grandchildren (2228 girls and 2181 boys) and about 6000 controls, about one-quarter of DES grandchildren are born prematurely. Preterm delivery exposes neonates to serious neonatal complications, including neurosensory disorders, disabilities and increased neonatal mor- tality. The more premature the baby, the greater the risk of complications. In the Réseau DES France study, cerebral palsy was more frequent in the DES grandchildren group: 59/10 000, versus 6/10 000 in the control group. A study conducted in the United States in about 4500 DES daughters found that preterm delivery occurred at a frequency of about 26%, much higher than that reported in controls. Neonatal mortality was 8 times higher among DES grandchildren, and the risk of stillbirth was twice as high. Other smaller studies have also shown an increased risk of preterm birth. A cohort study conducted in about 5000 DES grandchildren found that the risk of malformations of any type was higher than in the unexposed control group. Epidemiological studies, conduct- ed in several countries, found an increased frequency of hypospadias in DES grandsons. The relative risk was about 5 in the largest study. Other, less robust studies found no statistically significant difference. Several studies in several countries have shown a twofold increase in the risk of oesophageal atresia or tracheo- oesophageal fistula in DES grandchildren. The data on congenital heart defects or musculoskeletal malformations are limited and uninformative. Epidemiological studies have not identified a significant increase in the risk of gynaecological anomalies or cancers in DES granddaughters. Limited data are available on the risk of malformations in the children of DES sons. The data obtained in rodents exposed to DES (and other endocrine disruptors) make it entirely plausible that in utero exposure to DES, in humans too, provokes epigenetic effects that are passed on to future generations not directly exposed to DES. In practice, these data should be discussed with DES daughters, their partners and healthcare teams so that appropriate monitoring, clinical man- agement and follow-up can be arranged for both mother and baby. The harms of taking DES during pregnancy last for decades and affect future generations.

Lung maturity in esophageal atresia: Experimental and clinical study.

INTRODUCTION: Esophageal atresia and tracheoesophageal fistula (EA-TEF) survivors suffer respiratory morbidity of unclear pathogenesis. Defective lung morphogenesis has been described in the rat model. This study examined fetal lung growth and maturity in rats and patients with EA-TEF. METHODS: Pregnant rats received either adriamycin or vehicle. Control and adriamycin-exposed lungs, with and without EA-TEF, were weighed and processed for RT-PCR, DNA quantification, immunofluorescence and immunoblot analysis of TTF1, VEGF, Sp-B, and α-sma. Twenty human lungs were also processed for immunofluorescence and Alcian-blue staining. RESULTS: Lungs from fetuses with EA-TEF (E21) showed decreased total DNA; FGF7 and TTF1 mRNA expressions were upregulated at E15 and E18, respectively. Protein expression and immunofluorescent distribution of maturity markers were similar. Lungs from stillborns with EA-TEF showed decreased epithelial expression of Sp-B and VEGF whereas those from newborns tended to have less Sp-B and more VEGF and mucous glands. DISCUSSION: The lungs of rats with EA-TEF were hypoplastic but achieved near-normal maturity. Stillborns with EA-TEF exhibited an apparently disturbed differentiation of the airway epithelium. Newborns with EA-TEF demonstrated subtle differences in the expression of differentiation markers, and increased number of mucous glands that could influence postnatal respiratory adaptation and explain some respiratory symptoms of EA-TEF survivors.

Contractile profile of esophageal and gastric fundus strips in experimental doxorubicin-induced esophageal atresia.

Esophageal atresia (EA) is characterized by esophageal and gastric motility changes secondary to developmental and postsurgical damage. This study evaluated the in vitro contractile profile of the distal esophagus and gastric fundus in an experimental model of EA induced by doxorubicin (DOXO). Wistar pregnant rats received DOXO 2.2 mg/kg on the 8th and 9th gestational days. On day 21.5, fetuses were collected, sacrificed, and divided into groups: control, DOXO without EA (DOXO-EA), and DOXO with EA (DOXO+EA). Strips from the distal esophagus and gastric fundus were mounted on a wire myograph and isolated organ-bath system, respectively, and subjected to increasing concentrations of carbamylcholine chloride (carbachol, CCh). The isolated esophagus was also stimulated with increasing concentrations of KCl. In esophagus, the concentration-effect curves were reduced in response to CCh in the DOXO+EA and DOXO-EA groups compared to the control group (P<0.05). The maximum effect values (Emax) for DOXO+EA and DOXO-EA were significantly lower than control (P<0.05), but the half-maximal effective concentration (EC50) values were not significantly different when the three groups were compared (P>0.05). In response to KCl, the distal esophagus samples in the three groups were not statistically different with regard to Emax or EC50 values (P>0.05). No significant difference was noted for EC50 or Emax values in fundic strips stimulated with CCh (P>0.05). In conclusion, exposure of dams to DOXO during gestation inhibited the contractile behavior of esophageal strips from offspring in response to CCh but not KCl, regardless of EA induction. The gastric fundus of DOXO-exposed offspring did not have altered contractile responsiveness to cholinergic stimulation.

Maternal hyperthyroidism increases the prevalence of foregut atresias in fetal rats exposed to adriamycin.

PURPOSE: Gastrointestinal malformations such as esophageal atresia with tracheoesophageal fistula (EA/TEF) and duodenal atresia (DA) have been reported in infants born to hyperthyroid mothers or with congenital hypothyroidism. The present study aimed to test whether maternal thyroid status during embryonic foregut division has any influence on the prevalence of EA/TEF and DA in an accepted rat model of these malformations. METHODS: Pregnant rats received either vehicle or 1.75 mg/kg i.p. adriamycin on gestational days 7, 8 and 9. Transient maternal hyper or hypothyroidism was induced by oral administration of levothyroxine (LT4, 50 µg/kg/day) or propylthiouracil (PTU, 2 mg/kg/day), respectively, on days 7 to 12 of gestation. Plasma cholesterol, total T3, free T4 and TSH were measured at gestational days 7, 12, and 21. At the end of gestation, the mothers were sacrificed and embryo-fetal mortality was recorded. Fetuses were dissected to determine the prevalence of esophageal and intestinal atresias. RESULTS: At gestational day 12, mothers treated with LT4 or PTU had hyper or hypothyroid status, respectively; plasma cholesterol levels were similar. In the adriamycin-exposed fetuses from hyperthyroid mothers, the embryonal resorption rate and the prevalence of both EA/TEF and DA were significantly higher than in the other groups; maternal hypothyroidism during the same period did not have significant effect on the prevalence of atresias. CONCLUSIONS: Maternal hyperthyroidism during the embryonic window corresponding to foregut cleavage increased the prevalence of both EA/TEF and duodenal atresia in fetal rats exposed to adriamycin. This suggests that maternal thyroid hormone status might be involved in the pathogenesis of foregut atresias and invites further research on this likely clinically relevant issue in humans.

Altered Tbx1 gene expression is associated with abnormal oesophageal development in the adriamycin mouse model of oesophageal atresia/tracheo-oesophageal fistula.

INTRODUCTION: Oesophageal atresia/tracheo-oesophageal atresia (OA/TOF) frequently arises with associated anomalies and has been clinically linked with 22q11 deletion syndromes, a group of conditions due to Tbx1 gene mutation which include Di George syndrome. Tbx1 and Tbx2 genes modulate pharyngeal and cardiac development, but are also expressed in the developing foregut and are known to interact with key signalling pathways described in oesophageal formation including bone morphogenic proteins. The adriamycin mouse model (AMM) reliably displays OA/TOF-like foregut malformations providing a powerful system for investigating the disturbances in gene regulation and morphology involved in tracheo-oesophageal malformations. We hypothesised that foregut abnormalities observed in the AMM are associated with altered Tbx1 and Tbx2 gene expression. METHODS: Time-mated CBA/Ca mice received intra-peritoneal injection of adriamycin (for treated) or saline (for controls) on embryonic days (E)7 and 8. Untreated Cd1 embryos were used to establish normal expression patterns. Embryos harvested on E9-E11 underwent whole-mount in situ hybridization with labelled RNA probes for Tbx1 and Tbx2. Optical projection tomography was used to visualise expression in whole embryos by 3D imaging. RESULTS: Tbx1 expression was visualised in a highly specific pattern in the proximal oesophageal endoderm in normal and control embryos. In the AMM, extensive ectopic expression of Tbx1 was detected in the dorsal foregut and adjacent to the TOF. The focally restricted oesophageal expression pattern persisted in the AMM, but was posteriorly displaced in relation to the tracheal bifurcation. Tbx2 was widely expressed in the ventral foregut mesoderm of controls, lacking specific endoderm localisation. In the AMM, altered Tbx2 expression in the foregut was only seen in severely affected embryos. CONCLUSION: Highly specific Tbx1 expression in the proximal oesophageal endoderm suggests that Tbx1 may be an important regulator of normal oesophageal development. Altered Tbx1 expression in dorsal foregut and adjacent to the TOF in the AMM suggests that Tbx1 gene disruption may contribute to the pathogenesis of tracheo-oesophageal malformations.

Esophageal atresia, small omphalocele and ileal prolapse through a patent omphalomesenteric duct: a methimazole embryopathy? [Corrected].

Newborns prenatally exposed to methimazole (active metabolite of carbamizole) for maternal hyperthyroidism may present some disorders in common, but the phenotype is not well defined. Choanal atresia is the most frequent, and other anomalies such as esophageal atresia and aplasia cutis were described with this embryopathy. Additionally, patent omphalomesenteric duct or Meckel's diverticulum in similar association was reported in some patients. The predisposed genetic background has to be considered. We report the case of a newborn exposed to carbamizole during the first 4 weeks of pregnancy and define an association related to prenatal methamizole exposure consisting of esophageal atresia, small omphalocele, and ileal prolapse through a patent omphalomesenteric duct.

Abnormal development of lung innervation in experimental esophageal atresia.

BACKGROUND/AIM: Patients with esophageal atresia and tracheo-esophageal fistula (EA-TEF) have chronic respiratory tract disease and deficient tracheal innervation. This study tests the hypothesis in rats with EA-TEF that deficient lung innervation could be one of the causes of respiratory disease. MATERIAL AND METHODS: Pregnant rats were treated with either 2 mg/kg i.p. adriamycin or vehicle on E7, E8 and E9. Lungs and tracheas were retrieved on E15, E18 and E21 (term: E22). Innervation was examined by regular (PGP 9.5 and GDNF) and whole-mount (PGP 9.5 and α-actin) immunohistochemistry. PGP 9.5 and GDNF mRNA were measured by real-time, quantitative RT-PCR and the levels of PGP 9.5 protein by immunoblot. Embryonic lung primordia harvested on E13 were cultured for 72 h and airway peristalsis was assessed under an inverted microscope. PGP 9.5 expression was then examined in explants by whole-mount immunohistochemistry and RT-PCR. Values were compared with non-parametric tests. RESULTS: Neural networks were present in both EA-TEF and control fetuses on E15, E18 and E21, but the neural network was obviously disorganized in whole-mount immunohistochemistry of EA-TEF. The pan-neural marker PGP 9.5 protein was increased at term whereas the neural chemo-attractant GDNF protein was unchanged. PGP 9.5 mRNA significantly increased from subnormal levels on E15 to very increased ones on E18 compared with controls. GDNF mRNA levels followed the same trend. Airway peristalsis of explanted embryonal lungs was similar in both groups. The neural networks were underdeveloped in these primordia, as assessed by whole-mount PGP 9.5 immunohistochemistry and RT-PCR. CONCLUSIONS: The development of respiratory tract innervation in adriamycin-induced EA-TEF was delayed and abnormally controlled in rats compared with controls. However, these deficiencies were apparently compensated for at term and had no effect on airway peristalsis. The possible significance of innervation anomalies for respiratory sequelae in EA-TEF patients deserves further investigation.

Mesenchymal expression of Tbx4 gene is not altered in Adriamycin mouse model.

PURPOSE: The Adriamycin mouse model (AMM) is a reproducible teratogenic model of esophageal atresia/tracheo-esophageal fistula (EA/TEF). Tbx4 is a member of the T-box family of transcription factor genes, which is reported to play a key role in separation of the respiratory tract and the esophagus. Up-regulation of Tbx4 is reported to cause TEF in the chick. Optical projection tomography (OPT) is a technique that allows three-dimensional (3D) imaging of gene expression in small tissue specimens in an anatomical context. The aim of this study was to investigate the temporo-spatial expression of Tbx4 during the critical period of separation of the trachea and esophagus in normal and Adriamycin treated embryos using OPT. MATERIALS AND METHODS: Time-mated CBA/Ca mice received intraperitoneal injections of Adriamycin (6 mg/kg) or saline on days 7 and 8 of gestation. Embryos were harvested on days 9-12, stained following whole mount in situ hybridization with labeled RNA probes to detect Tbx4 transcripts (n = 5 for each treatment/day of gestation). Immunolocalization with the endoderm marker Hnf3beta was used to visualize morphology. Embryos were scanned by OPT to obtain 3D representations of gene expression domains. Animal licence no. B100/4106. RESULTS: OPT elegantly revealed Tbx4 gene expression in both controls and in the disorganized pulmonary mesenchyme in the treated embryos. Although characteristic morphological abnormalities were observed in Adriamycin treated embryos, there was no significant difference in Tbx4 transcript distribution around lung primordia in comparison with control embryos. CONCLUSION: Although previously reported morphological abnormalities of notochord and esophagus were observed in AMM, Tbx4 gene expression was unaltered, suggesting that esophageal anomalies can occur in the presence of normal Tbx4 gene expression in this model.

Esophageal atresia and tracheoesophageal fistula in children of women exposed to diethylstilbestrol in utero.

OBJECTIVE: This study was undertaken to study the possible risk to mothers exposed in utero to diethylstilbestrol for offspring with esophageal atresia/tracheoesophageal fistula. STUDY DESIGN: Information on the mothers' in utero exposure to diethylstilbestrol was obtained from 3 sources: questionnaires completed by members of the parents' association of children with esophageal atresia/tracheoesophageal fistula; records of patients with esophageal atresia/tracheoesophageal fistula from a hospital database; and files from the Northern Netherlands EUROCAT birth defects registry. RESULTS: Three of 124 (2.4%) mothers from the parents' association and 6 of 192 (3.1%) mothers from the hospital cases reported in utero exposure to diethylstilbestrol. For 8848 children registered by EUROCAT, 33 (0.37%) mothers reported in utero exposure to diethylstilbestrol. Of 117 infants with esophageal atresia/tracheoesophageal fistula, 4 (3.4%) had a mother with in utero exposure to diethylstilbestrol; this association was statistically significant (P = .001). CONCLUSION: We report a possible transgenerational effect of diethylstilbestrol exposure in the cause of some cases of esophageal atresia/tracheoesophageal fistula.

Abnormal separation of the respiratory primordium in the adriamycin mouse model of tracheoesophageal malformations.

BACKGROUND/PURPOSE: Organogenesis relies on temperospatially coordinated signaling systems. The adriamycin rat model provided insights into the dysmorphogenesis of tracheoesophageal malformations. An adriamycin mouse model (AMM) would facilitate the investigation of their molecular pathogenesis. To transfer the knowledge gained from the rat, we describe a histological account of the critical period of organogenesis of these malformations in the AMM. METHOD: CBA/Ca mice were accurately time-mated (n = 18). Dams received intraperitoneal injections of adriamycin (6 mg/kg) (n = 12) or saline control (n = 6) on days 7 and 8. Fetuses were harvested on days 9, 9.5, 10, 11, 12, and 13, resin embedded, and 1-mum sections of the developing foregut were examined. RESULTS: Day 11 control fetuses showed normal separation of the respiratory primordium, with apoptotic bodies at the point of separation. A more caudal point of separation of the distal foregut without apoptotic bodies was found in 4 of 10 AMM fetuses. Day 13 AMM fetuses had dorsal or ventral outpouchings of the foregut, indicating which malformation they would develop. Abnormal branching of the notochord was seen from day 9.5 in AMM fetuses. This was not always associated with abnormal tracheoesophageal development. CONCLUSION: This study confirms that the abnormal observations made in the rat model apply to the mouse.

Adriamycin mouse model: a variable but reproducible model of tracheo-oesophageal malformations.

A spectrum of tracheo-oesophageal malformations is seen in humans: oesophageal atresia, tracheal agenesis and laryngotracheo-oesophageal clefts. They are thought to share a common but unknown aetiology. These birth defects are frequently associated with other VACTERL anomalies. The adriamycin rat model (ARM) has proved to be a valuable model of the VACTERL anomalies, illustrating the dysmorphogenesis of oesophageal atresia and tracheal agenesis. As organogenesis relies on temporaspatially co-ordinated signalling systems, the next step would be to study the molecular pathogenesis of tracheo-oesophageal malformations. However, the mouse is the foremost mammal studied by developmental biologists, offering an expanding wealth of knowledge and scientific research techniques with which to investigate these anomalies. A limited dose response analysis of the teratogenicity of adriamycin in the mouse has identified a dose and timing of injections that produced tracheo-oesophageal malformations and other VACTERL anomalies. A clear account of the types and variability of the tracheo-oesophageal malformations produced by this dose is essential in order to be able to plan and interpret any future investigations of early gestation fetuses. CBA/Ca mice were accurately time-mated (n = 10). Nine dams received intraperitoneal injections of adriamycin (6 mg/kg) and one control dam received saline injections, on days 7 and 8. Fetuses were harvested on day 18, near term. Tracheo-oesophageal malformations were examined by dissecting microscope and serial transverse sections. Results are reported in the standard teratological manner as mean percentage per litter (+/-SEM). The resorption rate of the adriamycin treated fetuses was 50.4%. There were 29 adriamycin treated fetuses for inspection. Tracheo-oesophageal malformations were found in 29.2% (+/-10.3), affecting five out of nine litters. Oesophageal atresia occurred in 15.6% (+/-8.1), laryngotracheo-oesophageal cleft in 10.4% (+/-7) and tracheal agenesis in 3.1% (+/-3.1). All of these malformations occurred with a tracheo-oesophageal fistula. Unlike the ARM, the AMM can produce fetuses with complete laryngotracheo-oesophageal cleft as well as oesophageal atresia or tracheal agenesis. Their occurrence was found to be reproducible but variable. These are important considerations when planning and interpreting experiments using this model.

Decrease of parafollicular thyroid C-cells in experimental esophageal atresia: further evidence of a neural crest pathogenic pathway.

Adriamycin-induced experimental esophageal atresia (EA) is often associated with malformations of neural crest (NC) origin, such as abnormal pharyngeal pouch derivatives like the thymus and the parathyroids. The aim of the present study was to examine whether NC-derived thyroid C-cells were abnormal in a rat model. Pregnant rats received intraperitoneally either 2 mg/kg Adriamycin (EA) or vehicle (controls) on days 8 and 9 of gestation. Fetuses were recovered on day 21, and blocks including the trachea and thyroid were fixed in formalin, coronally sectioned at 3-mum widths, and stained with standard hematoxylin and eosin until the largest area of thyroid was reached. From this point on, the 1st, 10th, and 20th slices were immunohistochemically stained with anti-calcitonin antibody. Positively-stained cells in each section of the gland were counted using a computer-assisted image analysis method, and the results were averaged. The distribution of the cells within the gland was assessed as well. Comparisons between EA and control rats were made by nonparametric tests with a significance threshold of p<0.05. The number of C-cells was dramatically reduced in EA animals compared with controls (32.4+/-36 vs. 92.3+/-60.5, p<0.001). Histology of the thyroid was similar in both groups, but the distribution of positive C-cells within the gland followed an abnormal pattern in EA rats. Adriamycin causes a pattern of NC-derived malformations, including a severe decrease in thyroid C-cells accompanied by abnormal distribution or migration patterns. These results represent further evidence of the involvement of NC organogenic control dysregulation in the pathogenesis of EA and its associated malformations. The similarities between the rat model and the clinical picture strongly support investigating other subclinical NC-derived anomalies in patients with EA.

Esophageal atresia and other visceral anomalies in a modified Adriamycin rat model and their correlations with amniotic fluid volume variations.

The Adriamycin rat model (ARM) has been used to produce visceral malformations in fetuses to explain the mechanisms of foregut division. The models vary in the dosage of Adriamycin (ADR) and in the number of applications. Our study of a modified ARM using 2.2 mg/kg of ADR for 2 days only, intraperitoneally in pregnant rats, is presented. A total of 81 fetuses were obtained with this model from the ADR group, 74 (91%) alive. Uretero-hydronephrosis (UHN) was observed in 70 fetuses (95%), esophageal atresia (EA) in 68 (92%), duodenal atresia (DA) in 68 (92%), bladder hypoplasia (BH) in 67 (90%), plus other malformations. In evaluating amniotic fluid (AF) volume of the fetuses with EA with tracheo-esophageal fistula (TEF) (group I) and EA without TEF (group II), both associated with bilateral UHN when compared with the control group (group III), groups I and II showed higher AF volume in groups I and II than the control group (group III) did ( p=0.0001). In conclusion, ARM was adequate to produce EA and other visceral malformations. The use of ADR in a higher dosage for a shorter period of time produced better results than those presented in previous literature. The increase of AF volume obtained in fetuses presenting EA plus bilateral UHN strongly suggests, despite ureteral dilatation (urinary obstruction), that a malformed communication may exist between the urinary system and the amniotic cavity, permitting the existence of polyhydramnios that is due to digestive obstruction such as EA and DA.

The development of the proximal oesophageal pouch in the adriamycin rat model of oesophageal atresia with tracheo-oesophageal fistula.

This study examined the morphological development of the proximal oesophagus in the Adriamycin-induced rat model of oesophageal atresia. The proximal oesophageal segment in oesophageal atresia with tracheo-oesophageal fistula (OA\TOF) has been assumed to be of similar embryological origin to the distal oesophagus. However, recent research using the Adriamycin model of OA\TOF has indicated that these structures may have a different origin. Time-mated Sprague-Dawley rats were administered either Adriamycin intraperitoneally or saline of an equivalent volume between days 6-9 of gestation. The rats were sacrificed between days 11-19 of gestation, their embryos removed and histologically sectioned. These sections were analysed to observe the morphological changes occurring in the proximal foregut. The proximal oesophageal pouch first appeared on day 15.25 as a dorsal outpouching of the proximal foregut immediately cranial to an area of apoptosis in the dorsal epithelium of the distal pharynx. It elongated through a process of cellular proliferation until it was clearly formed on day 16. Relatively little growth occurred from days 17-19. In the rat developing oesophageal atresia, the proximal oesophageal pouch has an origin different to that of the distal oesophagus. This study may explain the difference in immunohistological properties and intrinsic nervous supply between the proximal and distal oesophageal segments in oesophageal atresia.

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.

Gastric smooth muscle contractility changes in the esophageal atresia rat model: an in vitro study.

PURPOSE: The aim of the study was to investigate the gastric smooth muscle reactivity in the Adriamycin-induced esophageal atresia (EA) rat model. METHODS: The fetuses were divided into 3 groups. The control group was exposed to saline. The second group was comprised of fetuses that were exposed to Adriamycin but did not have EA (Adriamycin-no-EA group). The third group was comprised of fetuses that were exposed to Adriamycin and had EA (Adriamycin-EA group). Gastric fundus strips were studied in vitro for their contractile response to receptor activation in the 3 groups. RESULTS: Contractile responses of gastric smooth muscle to carbachol and KCl were increased in the Adriamycin-EA group compared with the Adriamycin-no-EA group. Also serotonin-induced contractile response in the Adriamycin-EA group decreased compared with the Adriamycin-no-EA group. Relaxation of gastric smooth muscle strips to isoproterenol was comparably unaffected in the Adriamycin-EA and Adriamycin-no-EA groups. Likewise, no change in the response to agonist studies was observed between the control and Adriamycin-no-EA groups. The relaxant response to papaverine was not different in the 3 groups. CONCLUSIONS: This study found changes of receptor-dependent and receptor-independent contraction of the gastric fundus smooth muscle in the fetuses with EA. Therefore, impaired contractile responses may be, at least in part, a contributing factor in the abnormal gastric motility seen in EA.

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.

Differences in the levels of Sonic hedgehog protein during early foregut development caused by exposure to Adriamycin give clues to the role of the Shh gene in oesophageal atresia.

Sonic hedgehog (Shh) protein is a signalling molecule that is important for defining patterning in the development of vertebrates. Shh has been shown to be involved in the morphogenesis of many organ systems such as notochord, floor plate and limbs and in the development of the left-right axis in vertebrates. In this study we show that high levels of protein occur during the initial period of foregut differentiation into trachea and oesophagus, and that low levels of Shh protein are seen during early development of the foregut where oesophageal atresia and/or tracheo-oesophageal fistula ensue. These studies show that Shh protein is expressed in the rat foregut during embryogenesis, and its level declines as the embryo approaches birth. In adriamycin-treated rats the level of Shh protein expression is very low without any time-dependent changes. These results are consistent with the hypothesis that adriamycin influences the Shh signalling pathway, resulting in disruption of normal development of the foregut.