Sept. 14, 2001
Volume XXXIV, No. 37



In Memoriam

Of Note


Results included in Proceedings of the National Academy of Sciences

Oxidative stress to DNA increases with age, study finds

Photo of hooding

Dr. Arlan Richardson (right) hoods Michelle Hamilton during a graduation ceremony for students in the Graduate School of Biomedical Sciences. She earned a Ph.D. in physiology. Hamilton's dissertation suggests that oxidative stress to DNA increases with age.

The older a rodent is, the greater the chance that its genes have been damaged by oxidation. That's the conclusion of a study conducted at the Health Science Center and published in the Aug. 21 issue of the Proceedings of the National Academy of Sciences-USA.

The researchers compared levels of a key stress marker, 8-oxo-2-deoxyguanosine (oxo8dG), in rats and mice of various ages. The scientists scanned liver, kidney, brain, heart and muscle tissue, finding that the older the rat or mouse, the higher the level of the marker. Oxo8dG is described as a modification of a genetic sequence.

One theory of aging is that oxidants are generated during normal metabolism and can react with DNA, the genetic code, causing damage. The body continuously repairs its own DNA, but any oxidative lesion that is not repaired can lead to mutations, increasing the risk of cancer.

This study suggests that the age-related increase in oxidative lesions in DNA could be an important factor in the age-related increase in most cancers. Age is well documented to be the leading risk factor for most cancers.

The study was part of a Ph.D. dissertation written by Michelle Hamilton, a former graduate student in the department of physiology, with assistance from faculty including her mentor, Dr. Arlan G. Richardson, professor of physiology, director of the Aging Research and Education Center, and senior career research scientist with the South Texas Veterans Health Care System, Audie Murphy Division.