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Endogenous mutagens and the causes of aging and cancer
Authors:Bruce N Ames and Lios Swirsky Gold
Institution:

1 Division of Biochemistry and Molecular Biology, Barker Hall, University of California, Berkeley, CA 94720, U.S.A.

2 Cell and Molecular Biology Division, Lawrence Berkeley Laboratory, Berkeley, CA 94720, U.S.A.

Abstract:A very large oxidative damage rate to DNA occurs as part of normal metabolism. In each rat cell the steady-state level is estimated to be about 106 oxidative adducts and about 105 new adducts are formed daily. It is argued that this endogenous DNA damage is a major contributor to aging and the degenerative diseases of aging, such as cancer. The oxidative damage rate in mammalian species with a high metabolic rate, short life span, and high age-specific cancer rate is much higher than the rate in humans, a long-lived creature with a lower metabolic rate and a lower age-specific cancer rate. It is argured that deficiency of micronutrients, such as dietary antioxidants or folate, is a major contributor to human cancer and degenerative diseases.

Understanding the role of mitogenesis in mutagenesis is critical for clarifying the mechanisms of carcinogenesis and interpreting high-dose animal cancer tests. High-dose animal cancer tests have been done mainly on synthetic industrial chemicals, yet almost all of the chemicals humans are exposed to are natural. About half of natural chemicals tested in high-dose animal cancer tests are rodent carcinogens, a finding that is consistent with the view that high-dose tests frequently increase mitogenesis rates. Animals have numerous defenses against toxins that make them very well buffered against low doses of almost all toxins, whether synthetic or natural.

Keywords:Mutation  Cancer  Aging  Promotion
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