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261.
Culture and behavior of osteoblastic cells isolated from normal trabecular bone surfaces 总被引:6,自引:0,他引:6
Pierre J. Marie Abderrahim Lomri Ayman Sabbagh Michel Basle 《In vitro cellular & developmental biology. Plant》1989,25(4):373-380
Summary We report the characterization of human osteoblastic cells that were derived from the surface of trabecular bone fragments.
After removal of bone marrow cells, the bone lining osteoblastic cells lining the bone surface were obtained by migration
and proliferation from the trabecular surface onto a nylon mesh. The isolated population proliferated in culture and exhibited
osteoblastic phenotype. Cultured cells show a regular arrangment in vitro and exhibited multiple interconnecting junctions
on scanning electron microscopic examination. Immunocytochemical staining showed that the cells produced almost exclusively
type I collagen. Bone-surface-derived cells responded to 1–34 human parathyroid hormone by increasing intracellular cyclic
AMP. Cell cultures exhibited high alkaline phosphatase activity, which was unaffected by 1,25 (OH)2 vitamin D. Untreated cells produced high levels of osteocalcin, a bone-specific protein, and they responded to 1,25(OH) vitamin
D by increasing osteocalcin synthesis in a dose-dependent manner. Although cells cultured for up to 5 mo. still produced osteocalcin,
the response to 1,25(OH)2D decreased after multiple passages. This study shows that the bone cell populations isolated from trabecular bone surface
are enriched in osteoblast precursors and mature osteoblstic cells. 相似文献
262.
The addition of methotrexate to the assay system of thymidylate synthetase caused a reduction in the activity of the enzyme but addition of methotrexate to the culture of phytohemagglutinin stimulated normal human lymphocytes caused an increase in the activity of the enzyme which was abolished by the addition of actinomycin D or cycloheximide. These studies suggest that the antimetabolite augmented the enzyme activity by modulating the gene for the enzyme. This modulation of the gene could have been achieved by the thymineless state brought about by methotrexate or the antimetabolite could have affected gene reodont or brought about amplification of the gene. The results of the nucleoside incorporation were consistent with a thymidylate synthetase block; however, other explanations are offered. 相似文献