Hampered Lung Maturation in Methimazole-Induced Hypothyroidism in Fetal Chicken: Morphological and Molecular Correlates to Human Fetal Development.

BACKGROUND: Molecular understanding of lung development is crucial for developing therapies and diagnostic tools. Animal models with altered thyroid hormone signaling provide mechanistic insight into thyroid-dependent neonatal lung disease. Repression of Klf2 (Krüppel-like factor 2), a suggested T3 target gene, is associated with disrupted lung development in mice. Klf2 is proposed to be specifically involved in type I pneumocyte differentiation. OBJECTIVES: To explore mechanisms of thyroid-dependent lung disease, we studied developing chicken fetuses with experimentally induced hypothyroidism. METHODS: Morphology and the expression of a panel of molecules linked to Klf2 were assessed using histology, immunohistochemistry, Western blot and qPCR. RESULTS: Methimazole injections at E14 hampered lung maturation. The effects of methimazole were evident in several tissue compartments, and impacted on both pneumocyte and vascular differentiation, suggesting cellular and molecular pleiotropy. CONCLUSIONS: Concomitant expression changes in a panel of selected microRNAs regulated by Klf2 suggest importance in lung development. These microRNAs may thus represent potential clinical targets and diagnostic and prognostic tools in thyroid-dependent lung disease.

Type I and II pneumocyte differentiation in the developing fetal chicken lung: conservation of pivotal proteins from birds to human in the struggle for life at birth.

BACKGROUND: Antenatal corticosteroids and surfactant replacement therapy have dramatically reduced mortality caused by lung disease in premature babies. Knowledge about mechanisms regulating epithelial differentiation of the respiratory membrane is limited, as are effects of pharmacological interventions. The chicken fetus is a valuable model for exploring pharmacological actions on developing organs. However, more precise information about the timing of developmental events in the chicken lung is needed for human correlation. OBJECTIVES: Characterization of morphological development and protein expression in the respiratory membrane of the developing chicken lung to create a platform for pharmacological testing in a human context. METHODS: Fetal chicken lungs, embryonic days (E) 7-20, were characterized by morphology and protein expression of epithelial differentiation markers. This was compared with publications on the same processes during human lung development. RESULTS: The respiratory membranes of developing chicken and human lungs show basic similarities. In chicken, surfactant protein B is expressed in cuboidal type II epithelial cells from E17. Aquaporin 5 is expressed in the epithelium from E7 and selectively in type I pneumocytes from E17. The type I pneumocyte and endothelial marker, caveolin 1, is expressed in the endothelium from E7 to E20. CONCLUSION: Despite phylogenetic distance, central aspects of cellular development in the chicken and human lung are similar. The fetal chicken model has important additional advantages to mammalian models, including fetal independence and short incubation, and is thus well suited for in vivo studies of lung maturation relevant to human development.

X-linked congenital adrenal hypoplasia with hypogonadotropic hypogonadism caused by an inversion disrupting a conserved noncoding element upstream of the NR0B1 (DAX1) gene.

CONTEXT: X-linked congenital adrenal hypoplasia with hypogonadotropic hypogonadism (AHCH) is known to be caused by coding mutations in the nuclear receptor subfamily 0, group B, member 1 (NR0B1) gene, encoding the transcriptional repressor dosage-sensitive sex-reversal adrenal hypoplasia critical region on the X chromosome protein 1 (DAX1). OBJECTIVE/PATIENTS: Four males in a family were affected by AHCH. Our aim was to locate the genetic cause of their disease, knowing that they had no mutation in the obvious candidate gene, NR0B1. DESIGN: Linkage analysis of the X chromosome and mutational screening of conserved noncoding regions upstream of NR0B1 were performed. To functionally characterize the genetic defect, studies of transcription and expression of DAX1 and steroidogenic factor 1 (SF-1) were done. RESULTS: A 60 Mb inversion on the X chromosome with one of the inversion breakpoints located in a conserved noncoding region 4 kb upstream of NR0B1 was detected. The inversion causes relocation of a putative SF-1 binding site implicated in murine gonadal development. A reporter construct lacking this enhancer element upstream of NR0B1 was unresponsive to SF-1 transcriptional activation. Immunohistochemistry suggested that the inversion leads to SF-1 silencing in the patients' testes both in childhood and in adult life. CONCLUSION: We report a noncoding mutation causing AHCH, an inversion resulting in a phenotype similar to what is caused by intragenic NR0B1 null mutations. The inversion seems to disrupt and/or relocate regulatory sites crucial in DAX1 expression.

Niemann-Pick disease type C2 presenting as fatal pulmonary alveolar lipoproteinosis: morphological findings in lung and nervous tissue.

BACKGROUND: Niemann-Pick disease type C1 (NPC1) and type C2 (NPC2) display the same pattern of neurovisceral storage due to deficiencies within lysosomes. NPC2 is a much rarer condition, and as reports on the pathological changes are scarce, the morphological findings in the lungs and brain in two siblings who died at an early age from pulmonary involvement are described. The diagnosis of NPC2 was confirmed at postmortem mutational analysis. CASE REPORTS: Both siblings presented with postnatal conjugated hyperbilirubinemia. They subsequently developed progressive respiratory insufficiency with opacification of the lungs on X-ray examination and died at the ages of 8 and 13 months. The lungs contained intra-alveolar accumulation of periodic acid-Schiff positive material, foamy macrophages, and hyperplasia of the alveolar cells, consistent with pulmonary alveolar lipoproteinosis. On neuropathological examination, storage material in swollen perikarya in the deep cerebellar nuclei, thalamus, medulla oblongata, and in the paravertebral ganglion cells was found. Meganeurites were present in the cerebral cortex. A few axonal spheroids were also observed. There seemed to be a reduced number of Purkinje cells in the cerebellum. CONCLUSIONS: Evidence that NPC2 is associated with severe pulmonary alveolar lipoproteinosis is supported. There were extensive neuropathological changes with storage material in swollen perikarya and a few axonal spheroids.

Bronchioalveolar lavage with perfluorochemical liquid during conventional ventilation.

OBJECTIVE: Therapeutic approaches with bronchioalveolar lavage are currently used in infants with severe alveolar space-occupying material. In many circumstances, bronchioalveolar lavage has been performed in conjunction with extracorporeal membrane oxygenation. CASE REPORT: A 2-month-old boy with severe respiratory failure requiring assisted ventilation did not respond to any conventional treatments, including surfactant. An open-lung biopsy showed intra-alveolar accumulation of proteinaceous material and foamy macrophages but was not diagnostically conclusive. Therapeutic trials with bronchioalveolar lavage using normal saline were unsuccessful, causing episodes of severe hypoxemia. Then, bronchioalveolar lavage during conventional mechanical ventilation was performed with the use of a medical-grade perfluorochemical liquid (perfluordecalin). After instillation of liquid (10 mL/kg), the lungs were refilled three times during the first 24 hrs and repeated 48 hrs later. During perfluorochemical liquid treatment, the infant's condition remained stable, with small improvements in pulmonary mechanics. Suction from the endotracheal cannula yielded only small amounts of gelatinous material. Considering the progression of the disease and just minimal pulmonary improvements by this intervention, further treatment was considered futile. Support was, thus, minimized, and the infant died a few days later. An autopsy revealed the diagnosis to be consistent with Niemann-Pick C2 disease. CONCLUSION: This study demonstrated that bronchioalveolar lavage with perfluorochemical liquid could be performed safely during conventional mechanical ventilation without the additional support of extracorporeal membrane oxygenation in infants with severe alveolar space-occupying material.

[Laparoscopic treatment of splenic cysts]. / Laparoskopisk behandling av miltcyster.

Splenic cysts are uncommon. The symptoms are usually vague, but complications such as haemorrhage, rupture and infection may occur. The majority of splenic cysts are seen in children and young adults. Surgical treatment is recommended and splenic preservation is advantageous. We present two patients with splenic cysts successfully treated with laparoscopic resection of the cyst wall.