Word: cellular
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Dates: during 1990-1999
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...first idea researchers have explored is broadly thought of as the cellular-damage model of aging. For any complex system--whether it's made of inorganic metal or protoplasmic goo--the mere act of doing the work it was designed to do carries a price. No sooner does the hardware begin operating than its parts begin wearing out and its journey to the junkyard begins. Cells are not spared this fate, and one of the functions that takes the most out of them is the job of processing food...
...antioxidants, such as beta-carotene, actually seem to be associated with an increase. In either event, few contemporary aging researchers think self-medicating at a salad bar is the best way to extend the human life-span. Far more promising might be new research into another by-product of cellular metabolism: glycosylation--or what cooks call browning...
Although he made history when he discovered the limits on cell replication in the lab, Hayflick left a question unanswered: why the cells die. In the years following his work, biologists mapping human chromosomes looked for a gene that enforced cellular mortality, but found nothing. One thing that did catch their eyes, however, was a small area at the tip of chromosomes that had no discernible purpose. Dubbed a telomere, the sequence of nucleic acids did not appear to code for any traits. Instead it resembled nothing so much as the plastic cuff at the end of a shoelace that...
...works. The genetic sequence he discovered codes for the enzyme helicase, which is responsible for unzipping the DNA double helix before it replicates. If this unzipping is disrupted, helicase can't tweeze out mutations that randomly occur and instead allows them to pass through to the next cellular generation. Accumulate enough glitches, and diseases of aging develop. "We know that DNA is being damaged at a high rate," he says. "Knowing that a helicase is responsible gets us closer to solving the mystery...
Still other researchers are using what they've learned about telomeres and the other cellular mechanisms to attack the diseases that keep the very old from becoming still older. Researchers at Geron Pharmaceuticals recently published a study in which telomerase RNA was used to block the enzyme in a cancer culture, leading to withering of telomeres and the death of the no-longer-so-prolific cells. Elsewhere, investigators are looking into using the anticaramelization drug pimagedine to help clear arteries and improve cardiac health. Remove heart disease from the constellation of late-life illnesses, and you add three years...