In article <6r2atr$j8d at sjx-ixn8.ix.netcom.com>,
Steven B. Harris <sbharris at ix.netcom.com> wrote:
>In <35D45F39.E9F946E at castles.com> gtwolke <gtwolke at castles.com> writes:
>> There isn't any reason to think that "aging" is caused by entirely
>or mostly by free radicals from the mitochondria. Many organisms have
>mitochrondria, but don't age-- therefore the free radical made by
>mitochondria are obviously fully containable by a healthy organism.
That seems pretty convincing!
>If they do damage in aging, that may be because aging screws up the repair
>systems. But that doens't mean the mitochondria are the cause of
>aging-- in that cause they would simply be one more system that causes
>problems as aging takes out the control and repair systems. Attempts
>to influence rate of aging in cells by fooling with mitochondria
>haven't been sucessful. The Hayflick limit, for example, is not
>influencable by damping out oxidative metabolism in mitochondria.
>> As organisms that do age get older, their mitochondria take a
>beating. But so does the rest of them. That's not good evidence.
> Steve Harris, M.D.
Another theory that seems to have some currency these days (it made the
pages of The Economist's "Science and Technology" section, for example)
is that aging is caused largely by damage to the "telomeres", which are
end-segments of the DNA molecule which fail to get reproduced at the
outer ends each time the DNA splits. After many cell divisions,
the telomeres are used up and what fails to reproduce correctly is "live"
nucleotides at the ends of the DNA molecule, i.e. the information-bearing
portion of the DNA starts to be modified. This process continues as
further cell divisions occur, and pretty soon the DNA becomes so corrupted
that subsequent cells in the line can't function properly or even remain
alive.
And there's research on an enzyme called "telomerase" which supposedly
is able to rebuild the telomeres. I've seen speculation (probably in
the aforementioned Economist article) that possibly telomerase will
serve as the "Fountain of Youth" drug that everyone who's not tired of
living has always wanted. Unfortunately, this particular FOY drug
wouldn't rejuvenate somebody who was very far along in the aging process,
but COULD halt further degeneration by saving those cells that had not
lost any of their information-bearing genetic material.
-John Sangster
Wellesley Hills, MA
