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Lung-derived growth factors : possible paracrine effectors of fetal lung development
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|Title:||Lung-derived growth factors : possible paracrine effectors of fetal lung development|
|Authors:||Montes, Ana Maria|
|Keywords:||Lungs -- Growth|
Fetus -- Growth
|Abstract:||Morphogenesis involves the specific arrangement of embryonic cell populations which ultimately results in organs with unique structures. Substantial evidence suggests that cell and tissue interactions are the primary regulatory mechanisms for the developmental process. A potential role for paracrine secretions in lung organogenesis has been hypothesized (Alescio & Piperno, 1957). These studies present direct support for the paracrine model by demonstrating the presence of locally produced mitogenic/maturational factors in fetal rat lung tissue. Conditioned serum free medium (CSFM) from nineteen-day fetal rat lung cultures was shown to contain several bioactive peptides as detected by 3H-Thymidine incorporation into chick embryo and rat lung fibroblasts, as well as 14C-choline incorporation into surfactant in mixed cell cultures. Using ion-exchange chromatography and Sephadex gel filtration, a partially purified mitogen, 11-111, was obtained. Although II-III cross-reacts in the somatomedin-C (Sm-C) radioimmunoassay, disc polyacrylamide gel electrophoresis demonstrates that this component has an electrophoretic mobility [Rf value] of 0.59 (+/-0.02) and does not co-migrate with Sm-C in this system (Rf = 0.53 ) and, thus, is probably not authentic Sm-C. The partially purified II-III stimulates mitosis in chick embryo fibroblasts and post-natal rat lung fibroblasts. Multiplication in fetal rat lung fibroblast cultures is stimulated only when these are pre-incubated with a competence factor or unprocessed CSFM. This suggests the existence of an endogenously produced competence factor important in the regulation of fetal lung growth. Preparation II-III does not possess surfactant stimulating activity as assessed by 3H-choline incorporation into lipids in predominantly type-II cell cultures. However, a peak of surfactant stimulating activity was found to elute off Sephadex G-75 at a Kav = 0.23 (MW approx. 13 Kd) and was distinct from the mitogenic II-III peak (Kav = 0.50). These data demonstrate the presence of a maturational/ mitogenic factor, influencing type-II mixed cell cultures. In addition, II-III had been shown to play an autocrine role stimulating the proliferation of fetal lung fibroblasts. Finally, these data suggest the existance of a local produced competence factor.|
Thesis (Ph. D.)--University of Hawaii at Manoa, 1985.
Bibliography: leaves 103-111.
show 1 morex, 111 leaves, bound ill. 29 cm
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|Appears in Collections:||Ph.D. - Biomedical Sciences (Physiology)|
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