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Volume 15 (1996)
- Issue 4 Pages 189-
- Issue 3 Pages 161-
- Issue 2 Pages 123-
- Issue 1 Pages 21-
Volume 15, Issue 3
Displaying 1-3 of 3 articles from this issue
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Tsutomu KUMAZAKI, Masahiko NISHIYAMA, Youji MITSUI1996 Volume 15 Issue 3 Pages 161-169
Published: September 30, 1996
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSThe expression of fibronectin increases during aging. This is observed in human skin and lung fibroblasts and umbilical vein endothelial cells aged in culture. The enhanced expression in elderly persons is also suggested in experiments using skin fibroblasts and aortic endothelial cells isolated from donors of various ages. Thus, the increased expression of fibronectin during in vivo and in vitro aging is common in various types of cell and can be a useful marker of aging. To elucidate the mechanism of enhancement, we explored binding activities of nuclear proteins to the fibronectin promoter region. We could not find any drastic changes in binding activity during aging, but found increased binding activities in several regions of the promoter. These changes may cause enhanced expression in senescent cells.View full abstractDownload PDF (2342K) -
Yukiaki KURODA1996 Volume 15 Issue 3 Pages 171-178
Published: September 30, 1996
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSActivin A is a member of the transforming growth factor β (TGFβ) super-family. It has recently been found to have potent activity on mesoderm induction and on differentiation of cultured cells in vitro. In the present study, three types of morphologically different colonies, (A, B and C)were observed in clonal cultures of normal rat kidney cells, NRK-49F. The effects of activin A on the incidence of these different colonies, and the mode of proliferation of the cells in these clonal cultures were investigated. In control NRK-49F cell cultures, types A, B and C colonies were observed at 48%,50% and 2%, respectively. The addition of activin A enhanced the incidence of type A colonies, and reduced that of type B. At a concentration of 5 ng/ml, activin A enhanced specifically the incidence of type C colonies. Several colonies were observed, in which transmorphological changes from type A to B, type B to C and its reverse occurred within single colonies. In clonal NRK-49F cell cultures for 72 h in normal medium,15% of cells did not divide and remained single. The addition of activin A stimulated these quiescent cells to divide, and enhanced the proliferation of the cells, resulting in shortening the average cell cycle time.View full abstractDownload PDF (2807K) -
COMPARISON OF AGING AND IMMORTALIZATION PROCESS OF CELLS DERIVED FROM BRAINS OF NEWBORN AND OLD RATSEriko ABE, Takae YUASA, Tadashi KONDO, Yoichi KONDO, Toshiya TSUJI, Yu ...1996 Volume 15 Issue 3 Pages 179-185
Published: September 30, 1996
Released on J-STAGE: November 13, 2012
JOURNAL FREE ACCESSCells derived from the brains of seven newborn and seven 24-month-old rats were cultured and their aging and immortalization processes were analyzed without using mutagens or oncogenic DNA viruses. The number of cells having a proliferative potential was about 5.6 ×106/gm of brain tissue in newborn rats, whereas it was about 4.5 × 104/gm in old rats. Six of the 14 cultures demonstrated GFAP-positive and A2B5-negative cells, suggesting the presence of type-1 astrocytes in the cultures. Ten of the 14 cultures entered crisis (aging phase) mostly around the 10th population doubling level (PDL), followed by a lag period of cell growth. Then all the cultures, except one, were immortalized. However, four cultures (two from newborns and two from old rats) were immortalized without showing any noticeable crisis (aging). The donor age of rats did not have any significant effect on the immortalization process of the cells. These results suggest that the cells from the rat brain are not suitable for studying the mechanism of cellular aging because of the lack of well-demarcated aging phenomena. The post-crisis cultures had aneuploid cells but no specific chromosomal changes were found in the immortalized cell lines.View full abstractDownload PDF (1606K)
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