In a message dated 10/17/01 7:04:07 AM, bradbury@aeiveos.com writes:
>Rafal wrote:
>
>> The most quickly dividing cells (as in the small bowel, or the
>> hematopoietic system) are not most limiting for survival -
>> this seems to be most affected by postmitotic cell attrition, in the
>> brain, skeletal muscle, and myocardium, as well as problems with the
>> nuclear genome (leading to cancer).
>
>I think the tissues with rapidly dividing cells *do* contribute
>to some aspects of aging.
True, but Rafal's point is correct; while skin and immune system
deterioration cause trouble, heart disease, stroke, and cancer kill
far more people, and two of the biggest (heart arrhythmias and
cancer) increase very rapidly with age
>Postmitotic cell attrition in the brain *will* be a problem but
>it probably doesn't become significant until 200+ years. We
>will have to develop methods of spuring the neuronal stem
>cells to replace those lost and/or inducing greater plasticity
>for those remaining.
Loss of vision due to deterioration of optic nerves is a significant problem
even
at our current age span. I suspect similar problem with heart innervation
are a major cause of suddend cardiac deatch, via late-life arrhythmia.
Mitochondria are strongly suspected for the nnerve deterioration.
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