Book T of C
Chap T of C
This is the 2007 version. Click here for the 2017 chapter 10 table of contents.
All body processes are under genetic control. If DNA sequences degrade, cells eventually become senescent (aged and non-functional). A breakthrough in understanding the aging process was research on telomeres in the late 1990s. Telomeres are repetitive DNA sequences that serve as caps on the ends of chromosomes. Each time a cell divides, the telomeres shorten. Eventually the telomeres become too short to do their work, and the cell becomes aged or senescent (Pennisi, 1998).
What are telomeres? What is telomerase, and what happens when a gene for it is added to cells?
Telomerase is an enzyme that rebuilds telomeres after cell division. Most normal cells do not produce it, but in 1998, the research team of Shay, Wright, Chiu and colleagues found that they could add a gene for telomerase to existing cells. The result was immortalized cells that lived far past their normal life spans with no sign of aging or senescence. The cells did not form tumor-like colonies or exhibit any other abnormalities. These experiments were conducted in mice, so it is still unclear whether telomerase will be similarly harmless in humans (Ferber, 1999). Research on telomeres is "exploding" as researchers look for breakthroughs (Marx, 2002).
What is the best-known way to add years to your life?
Until telomerase or nerve growth hormone is available in vitamin pills, or the aging "program" is "deprogrammed," the best-known way to add years to your life is to go hungry. Researchers have known for years that a restricted diet can add years to the lives of animals. This is a robust effect, influencing everything from yeast to humans. However, to achieve the effect, one must live under near-starvation conditions.
Why are some lab workers taking resveratrol?
The same life-extending effect as starvation is achieved in mice with high dosages of the substance resveratrol found in the skins of grapes (and a few other places, like Japanese knotweed). This, too, is a focus of much research activity. Mice treated with high levels of resveratrol live as long as mice raised in near-starvation conditions, but they do it without restrictred food intake. Researchers have issued the usual cautions about extrapolating these results to humans, especially because the dosages of resveratrol given to the mice is much higher (in proportion to the body weight of the mice) than dosages given to humans. Nevertheless, one researcher said he thought it was revealing that most of the people doing the research had started to take smaller dosages of resveratrol supplements on their own.
Eventually, all this research into the causes of aging could conceivably result in the ability to "switch off" the aging process, resulting in humans who are essentially immortal...until some disease or accident damages them beyond repair. John Harris, a bioethicist at the University of Manchester in the United Kingdom, points out that immortality in humans would raise profound ethical problems and transform society. "Future children would have to compete with previous generations for jobs, space, and everything else." But few would turn down the chance to extend life. Harris thinks it is unlikely that life-extension techniques would be suppressed or made illegal, so society will eventually have to confront these issues (Harris, 2000).
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Copyright © 2007-2011 Russ Dewey