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Research paper thumbnail of Aging of mammalian cells in vitro

The purpose of this study was to examine the phenomenon of aging at the cellular level in vitro. ... more The purpose of this study was to examine the phenomenon of aging at the cellular level in vitro. Some of the biological mechanisms underlying the aging process, which may invoke a change at the level of the DNA were studied. Morphological changes were analysed with phase-contrast microscopy and functional changes by the use of tritiated thymidine in combination with autoradiography as well as by cell treatment with colchicine. A method is described for obtaining "aged" or "old" cells in vitro. In the human cells (human embryonic kidney) as well as the rat, mouse, and Syrian hamster cells, morphological changes in vitro are basically tha same as aging progresses. These include transformation to a polygonal, epithe Iia I-1ike shape; binucIeation; an accumulation of "age pigments" around the nucleus; the appearance of ragged edges of the eel I membrane; an increase in the overall cell size; and a loss of a regular (often parallel) orientation to adjacent cells. The mitotic rate and DNA-synthesizing capacity in "young" and "aged" cells were examined using autoradiography and cell treatment with colchicine. Evidence is presented that DNA-synthesizing aged cells are non-proliferating while DNA-synthesizing young cells are mitotically active. The significance of DNA-synthesis in non-dividing "aged" cells is discussed. The number of population doublings (generation times or cell divisions) that it takes hamster and mouse cells to age in vitro was also investigated. Thirteen and six cell generation times were found to cause hamster and mouse cells to age with a loss of proliferative capacity. The effect of various molarities of 4-nitroquinoline-1 oxide (4-NQO), on DNA of aged eel Is,which results in an unscheduled DNA-repair synthesis, I would also like to thank Dr. R. L. Noble, Cancer Research Center, University of British Columbia, for providing the necessary apparatus and equipment. The financfal support of a National Cancer Institute Studentship is gratefuI Iy acknowledged.

Research paper thumbnail of Aging of mammalian cells in vitro

Page 1. THE AGING OF MAMMALIAN CELLS in Vitro by BRAD ATCHISON B. S c . , S ir George W illiams U... more Page 1. THE AGING OF MAMMALIAN CELLS in Vitro by BRAD ATCHISON B. S c . , S ir George W illiams U niversity , 1969 AT hesis Submitted in P artial F ulfilmentofthe Requirements for the Degree of MASTER OF SCIENCE in the Department of Zoology ...

Research paper thumbnail of Aging of mammalian cells in vitro

The purpose of this study was to examine the phenomenon of aging at the cellular level in vitro. ... more The purpose of this study was to examine the phenomenon of aging at the cellular level in vitro. Some of the biological mechanisms underlying the aging process, which may invoke a change at the level of the DNA were studied. Morphological changes were analysed with phase-contrast microscopy and functional changes by the use of tritiated thymidine in combination with autoradiography as well as by cell treatment with colchicine. A method is described for obtaining "aged" or "old" cells in vitro. In the human cells (human embryonic kidney) as well as the rat, mouse, and Syrian hamster cells, morphological changes in vitro are basically tha same as aging progresses. These include transformation to a polygonal, epithe Iia I-1ike shape; binucIeation; an accumulation of "age pigments" around the nucleus; the appearance of ragged edges of the eel I membrane; an increase in the overall cell size; and a loss of a regular (often parallel) orientation to adjacent cells. The mitotic rate and DNA-synthesizing capacity in "young" and "aged" cells were examined using autoradiography and cell treatment with colchicine. Evidence is presented that DNA-synthesizing aged cells are non-proliferating while DNA-synthesizing young cells are mitotically active. The significance of DNA-synthesis in non-dividing "aged" cells is discussed. The number of population doublings (generation times or cell divisions) that it takes hamster and mouse cells to age in vitro was also investigated. Thirteen and six cell generation times were found to cause hamster and mouse cells to age with a loss of proliferative capacity. The effect of various molarities of 4-nitroquinoline-1 oxide (4-NQO), on DNA of aged eel Is,which results in an unscheduled DNA-repair synthesis, I would also like to thank Dr. R. L. Noble, Cancer Research Center, University of British Columbia, for providing the necessary apparatus and equipment. The financfal support of a National Cancer Institute Studentship is gratefuI Iy acknowledged.

Research paper thumbnail of Aging of mammalian cells in vitro

Page 1. THE AGING OF MAMMALIAN CELLS in Vitro by BRAD ATCHISON B. S c . , S ir George W illiams U... more Page 1. THE AGING OF MAMMALIAN CELLS in Vitro by BRAD ATCHISON B. S c . , S ir George W illiams U niversity , 1969 AT hesis Submitted in P artial F ulfilmentofthe Requirements for the Degree of MASTER OF SCIENCE in the Department of Zoology ...

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