http://repub.eur.nl/res/aut/1525/ List of Publications en http://repub.eur.nl/static-eur/img/logo.png http://repub.eur.nl http://repub.eur.nl/res/pub/31949/ 2012-01-01T00:00:00Z http://repub.eur.nl/res/pub/20322/ 2010-06-01T00:00:00Z Background: Fetal lung development requires proper coordination between lung epithelial and vascular morphogenesis. A major determinant in lung vascular development is vascular endothelial growth factor (VEGF), which is regulated by hypoxia-inducible factors (HIFs). VEGF is expressed in the airway epithelium, while its receptors (VEGFRs) are expressed in the pulmonary mesenchyme. The hypoxic environment in utero is beneficial for fetal organogenesis, especially vascular development. However, little is known about the expression of HIFs and VEGFR-2 in the human fetal lung in vitro. Objectives: The purpose of this study was to investigate the effects of hypoxia on fetal lung morphology and mRNA expression of VEGF, VEGFR-2, HIF-2α, and HIF-3α. Methods: An explant culture technique was used to study the effects of normoxic and hypoxic conditions on human fetal lung. Results: The morphology remained largely unchanged in explants cultured under hypoxic or normoxic conditions. Quantitative RT-PCR showed that the mRNA expression of VEGF-A, but not VEGFR-2 is upregulated in explants cultured at 1.5% compared with 21% oxygen. We observed a nonsignificant increase in HIF-2α and HIF-3α mRNA expression in explants cultured at 1.5% oxygen. These data suggest that the mRNA expression of VEGF, and possibly HIF-2α and HIF-3α, is regulated by hypoxia in the developing human lung. Conclusion: This lung explant culture model appears to be a valuable model to unravel the molecular mechanisms of human lung development. http://repub.eur.nl/res/pub/27223/ 2009-09-01T00:00:00Z Congenital diaphragmatic hernia (CDH) occurs in 1 in 3,000 newborns. Mortality and morbidity are due to the amount of pulmonary hypoplasia (PH), the response on artificial ventilation and the presence of therapy-resistant pulmonary hypertension. The pathogenesis and etiology of CDH and its associated anomalies are still largely unknown despite all research efforts over the past years. Several animal models have been proposed to study CDH. In this review we compare surgical, pharmacological and transgenic models, and discuss their strengths and limitations to study PH. http://repub.eur.nl/res/pub/32646/ 2009-08-13T00:00:00Z http://repub.eur.nl/res/pub/24445/ 2009-05-01T00:00:00Z Background: One proposed reason for the early resection of asymptomatic congenital cystic adenomatoid malformations is the theoretical benefit of optimizing compensatory lung growth during infancy and early childhood. Our aim was to determine if early lobectomy is associated with better long-term pulmonary function than lobectomy later in childhood. Methods: A retrospective chart review of children undergoing pulmonary lobectomy for benign disease from 1990 to 2006 was performed. Those having surgery before and after 2 years of age were compared. Forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) were used as indicators of pulmonary growth, with FVC less than 80% predicted and FEV1less than 80% consistent with impaired pulmonary function. Results: Of 115 patients identified, 14 had postoperative pulmonary function testing at a mean age of 10 years. Of these, 7 had lobectomy before and 7 had lobectomy after 2 years of age. There was no significant difference between groups in mean FVC (81.5 vs 83.3) or the number of children with FVC less than 80% predicted, nor was there a difference in mean FEV1(87.6 vs 82.9) or the number of children with FEV1less than 80%. Conclusions: Age at the time of lobectomy did not influence FVC or FEV1. These preliminary data suggest that early lobectomy does not confer an advantage to the child with respect to long-term pulmonary function. A prospective study is necessary to confirm or refute these findings in a larger group of children. http://repub.eur.nl/res/pub/36474/ 2007-05-01T00:00:00Z The perinatal changes in the pattern of expression of the thyroid hormone receptor (TR) isoforms TRα1TRα2, TRβ1, and TRβ2were investigated using in situ hybridization and immunohistochemistry, and RT-PCR and western blotting as visualization and quantification techniques respectively. In liver, lung, and kidney, TRα mRNA was expressed in the stromal and TRβ mRNA in the parenchymal component of the tissues. When compared with liver, TRα mRNA concentrations were tenfold higher in lung, kidney, and intestine, and 100-fold higher in brain, with TRα2mRNA concentrations exceeding those of TRα15- to 10-fold. Tissue TRβ1mRNA concentrations were similar in liver, lung, and brain, and 3- to 5-fold higher in kidney and intestine. None of the TRβ2mRNA could be detected outside the pituitary. Tissue TRα2and TRβ1protein levels reached adult levels at 5 days before birth, whereas TRα1protein peaked after birth. Because of the distinct time-course of thyroid hormone-binding receptors TRα1and TRβ1, we speculate that an initiating, TRβ1-mediated signaling from the parenchyma is followed by a TRα1-mediated response in the stroma. When compared with organs with a complementary parenchymal-stromal expression pattern, organs with extensive cellular co-expression of TRα and TRβ (brain and intestinal epithelium) were characterized by a very low TRα protein: mRNA ratio, implying a low translational efficiency of TR mRNA or a high turnover of TR protein. The data indicate that the TR-dependent regulatory cascades are controlled differently in organs with a complementary tissue expression pattern and in those with cellular co-expression of the TRα and TRβ genes. http://repub.eur.nl/res/pub/13189/ 2003-11-01T00:00:00Z Neonates with congenital diaphragmatic hernia (CDH) suffer from a diaphragmatic defect, lung hypoplasia, and pulmonary hypertension, with poor lung function forming the major clinical challenge. Despite prenatal diagnosis and advanced postnatal treatment strategies, the mortality rate of CDH is still high. CDH has been subject of extensive research over the past decades, but its etiology remains unknown. A major problem with CDH is the failure to predict the individual response to treatment modalities like high-frequency ventilation, inhaled nitric oxide, and extracorporeal membrane oxygenation. In this study, we tested the possibility that CDH lungs are surfactant protein deficient, which could explain the respiratory failure and difficulties in treating CDH infants. We investigated this hypothesis in the nitrofen-induced CDH rat model and assessed the cellular concentrations of surfactant protein (SP)-A, -B, and -C mRNA with a quantitative radioactive in situ hybridization technique. No differences were observed between control and CDH lungs for SP mRNA expression patterns. The cellular concentration (mean OD) of SP-A and SP-B mRNA was similar at all stages whereas the mean OD of SP-C mRNA and the volume fraction of cells (% Area) expressing SP mRNA was higher in CDH lungs at term. Immunohistochemical analysis revealed no differences between control and CDH lungs for SP protein expression. No differences in the mean OD or % Area for the SP mRNAs were found between the ipsi- and contralateral side of CDH lungs. We conclude that there is no primary deficiency of surfactant proteins in the nitrofen-induced CDH rat model. http://repub.eur.nl/res/pub/2607/ 2001-07-09T00:00:00Z The transcription factor GATA6 is expressed in the fetal pulmonary epithelium of the developing mouse lung and loss of function studies strongly suggested that it is required for proper branching morphogenesis and epithelial differentiation. We have further investigated the role of GATA6 in this process by utilizing a pulmonary epithelium specific promoter to maintain high levels of GATA6 protein during fetal lung development. Transgenic mice expressing Gata6 cDNA under the control of the human Surfactant Protein-C (SP-C) promoter were generated and their lungs were analyzed during fetal stages. Transgenic lungs exhibit branching defects as early as embryonic day (E) 14.5 and molecular analysis just before birth (E18.5) shows a lack of distal epithelium differentiation whereas proximal epithelium is unaffected. Electron microscopic analysis and glycogen staining confirm the lack of differentiation to mature Type II cells. Thus, elevated levels of GATA6 protein affect early lung development and in analogy to other GATA factors in other tissues, GATA6 also plays a crucial role in the terminal differentiation in this case of the distal pulmonary epithelium. http://repub.eur.nl/res/pub/23415/ 2001-07-03T00:00:00Z One of the prerequisites of life is the process of respiration in which an organism exchanges carbon dioxide for oxygen in order to obtain energy through the oxygenation of molecules containing carbon. The interfaces used by different organisms for gas exchange vary from simple diffusion between prokaryotic bacteria and the medium in which they reside, to a much more complex diffusible interface, namely a gas-exchanging organ also known as the lung used by higher eukaryotes, such as humans. The human lungs have an estimated 300.000.000 alveoli with a surface area of approximately 70 m2 by 0.1 flm in early adulthood (Comroe, 1965; Weibel, 1963) and is comprised of at least 40 differentiated cell types. The alveolar surface of the lung is surrounded by a capillary network that develops in close apposition. This enables gas exchange to occur with the blood that delivers the oxygen to the tissues. Therefore a 70 kg adult human can use 14.5 L oxygen per hour or 1020 molecules per second at rest. The oxygen demand can rise to approximately 330 L per hour during exercise (Comroe, 1965; Weibel, 1963). To establish such a highly complex organ, well-orchestrated cell interactions are required during development to generate a functional lung. http://repub.eur.nl/res/pub/9590/ 2001-01-01T00:00:00Z Recent loss-of-function studies in mice show that the transcription factor GATA6 is important for visceral endoderm differentiation. It is also expressed in early bronchial epithelium and the observation that this tissue does not receive any contribution from Gata6 double mutant embryonic stem (ES) cells in chimeric mice suggests that GATA6 may play a crucial role in lung development. The aim of this study was to determine the role of GATA6 in fetal pulmonary development. We show that Gata6 mRNA is expressed predominantly in the developing pulmonary endoderm and epithelium, but at E15.5 also in the pulmonary mesenchyme. Blocking or depleting GATA6 function results in diminished branching morphogenesis both in vitro and in vivo. TTF1 expression is unaltered in chimeric lungs whereas SPC and CC10 expression are attenuated in abnormally branched areas of chimeric lungs. Chimeras generated in a ROSA26 background show that endodermal cells in these abnormally branched areas are derived from Gata6 mutant ES cells, implicating that the defect is intrinsic to the endoderm. Taken together, these data demonstrate that GATA6 is not essential for endoderm specification, but is required for normal branching morphogenesis and late epithelial cell differentiation.