ISSN:0003-276X    

DOI:10.1002/ar.1092360102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092360103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092360104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092360105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractClusters of small‐granule endocrine cells, neuroepithelial bodies (NEBs), appear in the airway lining of pseudoglandular lungs, but their prenatal function has remained obscure. Transplacental labeling of S‐phase cells in Syrian golden hamsters has allowed us to relate NEBs to patterns of replication in the surrounding endoderm. Two methods were used: (1) continuous exposure to3H‐thymidine for the last 25% (4 days) of gestation, and 2) 2‐hr exposure to 5‐bromo‐2′‐deoxyuridine (BrdU) on fetal day 15.3H‐thymidine incorporation was assessed in autoradiographs of neonatal lung by grain counting from 923 nonendocrine and 251 endocrine cells in 28 airway epithelial terrains, each centered on a NEB: 12 in the perihilar, 8 in the middle, and 8 in the distal third of the left axial bronchus. Grain densities for 10–25 nonendocrine cells on either side of the NEB were plotted vs. position relative to the endocrine cell cluster and analyzed by rank‐order correlation and linear regression. Label was highest in cells closest to NEBs in all 12 terrains (P<0.05–0.001) in the perihilar airway, in 3 of 8 terrains (P<0.025–0.001) in the middle third of the bronchus, and in respective, pooled populations (P<0.001). The effect was not demonstrable in the distal third of the airway. In the 15‐day fetus 243 mm of airway perimeter were measured and 3,218 BrdU‐labeled epithelial cells counted from sections through the entire length of the left axial airway and the lobar bronchus, intermediate, and terminal bronchioles of the infracardiac (IC) lobe. Overall, 43% of BrdU‐labeled cells and only 24% of epithelium lay within 20 μm of NEBs. Preferential concentration of S‐phase cells around NEBs was significant (P<0.001) by X2test at all airway levels. Net density of NEB‐associated BrdU + cells was 10/mm of basal lamina in the trachea, rose distally along the left axial airway to 22/mm at the end of the undivided bronchus, and fell to 15/mm in the terminal channels. It was 9 cells/mm in terminal bronchioles of the infracardiac lobe. Regional differences in3H‐thymidine and BrdU labeling patterns can be correlated with differences in the age of NEBs. We conclude that NEBs regulate local cell proliferation in developing hamster airway, probably activated in a proximal‐to‐distal wave reflecting maturational changes in the NEBs along

ISSN:0003-276X    

DOI:10.1002/ar.1092360106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractFetal pulmonary neuroendocrine cells (PNECs) contain abundant gastrin‐releasing peptide (GRP, mammalian bombesin‐like peptide [BLP]). Previously, addition of bombesin resulted in increased fetal lung growth and maturation in utero and in organ cultures. A monoclonal antibody (mAb) to bombesin (2A11) blocked baseline automaturation of lung organ cultures in serum‐free medium. In the present study, we analyze lung development following daily in utero administration of 2A11 from gestational days 15–18. Fetal lung treated with 2A11 and then harvested on day 18 demonstrated a dose‐dependent decrease in surfactant phospholipid synthesis compared to controls treated with MOPC, an unreactive mAb. However, 2A11‐treated fetal lung harvested on day 17 showed paradoxical increases in3H‐choline incorporation into saturated phosphatidylcholine,3H‐thymidine incorporation into DNA, and relative numbers of differentiated type II pneumocytes. In serum‐containing day 17 lung organ cultures, 2A11 stimulated choline and thymidine incorporation. Since epidermal growth factor (EGF) is the only agent besides bombesin known to stimulate both fetal lung growth and maturation, we added EGF to serum‐free cultures and reconstituted the stimulatory effects. A murine EGF receptor mAb (ERA) blocked 2A11‐induced lung growth and maturation in serum‐containing cultures, and this effect was overcome by adding EGF. In vivo, ERA also blocked stimulatory effects of 2A11 in fetal lung on day 17. These observations suggest that EGF receptor up‐regulation may maintain lung growth and maturation if BLP levels are diminished on day 17. Nonetheless, BLPs appear to be involved in lung maturation on day 18, supporting a role for PNECs in normal lung developmen

ISSN:0003-276X    

DOI:10.1002/ar.1092360107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractSuccessful isolation and culture of pulmonary neuroendocrine cells (PNEC) is essential for the investigation of cellular and membrane properties of these cells. Such studies are important to define the functional role for PNEC but are hampered by their scant numbers and widespread distribution within the pulmonary epithelium. Several in vitro methods for the isolation and culture of these cells have been described over the past decade, including organ culture, isolation of single cell suspensions enriched for PNEC, and immunomagnetic cell separation techniques. This paper reviews the various methods and discusses their advantages and pitfalls. © 1993 Wiley‐Liss, I

ISSN:0003-276X    

DOI:10.1002/ar.1092360108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractPulmonary neuroendocrine (NE) cells including the innervated clusters of NE cells—neuroepithelial bodies (NEB)—are difficult to study because of their small numbers and diffuse distribution within the airway mucosa of the lung. We have previously reported a method for isolation and culture of NE cells from rabbit fetal lung using a combination of mechanical and enzymatic dissociation followed by gradient centrifugation. This method provides single cell suspension of mixed lung cells enriched in NE cells, particularly those originating from NEB.This study further validates our in vitro model by detailed morphologic characterization of cultured NEB cells using high resolution light microscopy, transmission and scanning electron microscopy, HPLC for detection of serotonin (5‐HT), and molecular (Northern blot) analysis of mRNA encoding for 5‐HT synthesizing enzymes, tryptophane hydroxylase, and aromatic L‐amino acid decarboxylase. In addition to effects of hypoxia on NEB cells in vitro were investigated to define the role of these cells as possible airway chemoreceptors. Exposure of NEB cultures to hypoxia resulted in decreased intracellular content of 5‐HT accompanied by increased exocytosis of dense core vesicles (DCV). The amount of 5‐HT release correlated with the degree of hypoxia, suggesting modulation by ambient pO2levels. The role of Ca2+ions in exocytosis of DCV and 5‐HT release from NEB cells was tested in experiments with Ca2+ionophore (A23187). Exposure of cultures to 5 μg/ml of ionophore resulted in up to 40% reduction in 5‐HT content of NEB cultures as well as increased exocytosis of DCV.Our overall findings are consistent with a view that NEB cells are chemosensory in nature and that Ca2+signaling pathway is involved in stimulus‐secretion coupling. Further refinements in cell separation and culture methodology are required before more detailed investigation of NEB cell membrane properties, signal transduction mechanisms, and intracellular signaling pathways can be carried out. ©

ISSN:0003-276X    

DOI:10.1002/ar.1092360109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

摘要:

AbstractPulmonary neuroendocrine cells (PNEC) are numerous in the fetus where they have been implicated to have a role in fetal lung development. We assessed the effects of putative growth factors, gastrin releasing peptide (GRP), cholecystokinin (CCK), gastrin (GN), serotonin (5‐HT), and epidermal growth factor (EGF), some of which are produced by PNEC, either alone or in combination, on cultured fetal rabbit PNEC from 20, 24, and 28 day fetuses. GRP increased the total protein of the cultures over a 7 day period in an age‐dependent manner, with greatest effect in cultures from the 24 day fetus, no effect with the 28 day fetus, and an inhibitory effect on 20 day cultures. This was accompanied by an increase in PNEC, which could be blocked by treatment of the cultures with a monoclonal antibody to GRP (2A11). There was no increase in3H‐thymidine labeling of PNEC in GRP treated cultures but an increase in numbers of cells partially stained for 5‐HT, suggesting the induction of a precursor cell. Other growth factors had neither an inhibitory nor a stimulatory effect either alone or in combination with GRP. Preliminary studies with125I‐GRP receptor localization suggests that the GRP receptor is mostly expressed on pulmonary fibroblasts, and less on epithelial cells, so that the role for GRP in fetal lung development, at least in the rabbit, is probably indirect, acting via a paracrine mechanism. © 1993 Wiley

ISSN:0003-276X    

DOI:10.1002/ar.1092360110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY

ISSN:0003-276X    

DOI:10.1002/ar.1092360111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1993

数据来源: WILEY