Replies to post #43341 on Biotech Values

[DewDiligence]

Re: Facial aging

I understand your points and agree with most of them. However, I think UV radiation—especially UVA, which is not effectively blocked by most sunscreens—does play a large role in what we perceive as an aged appearance.

For the sake of discussion, say someone wore an opaque mask or sunblock every time they went outside during their entire life, including childhood. I claim that, at age 60, such a person’s skin would likely appear to be 40—or less.

[rfj1862]

>In the condition Progeria children born with this congenital disorder begin to assume the appearence and disabilities of old age typically well before they reach ten years of age.<

The primary defect in these children is not shortened telomeres. It's a mutation in a DNA helicase that is involved in homologous DNA repair and, probably, in nonhomologous end-joining pathways. The gene (WRN) may be involved in resolving something called the Holliday junction, a 4-stranded DNA intermediate in the homologous DNA repair pathway. If the Holiday junction is not resolved, it can lead to multiple DNA breaks, which of course may lead to all sorts of problems if improperly repaired or left unrepaired.

In short, aging--whether it be 'natural', or accelerated by environmental insults (eg, UV radiation, ionizing radiation, smoking, caffeine, etc) is probably caused primarily by unrepaired or improperly repaired DNA damage.

Shortened telomeres are a secondary consequence of Werner's syndrome. I don't think this is the primary defect.

[DewDiligence]

I think Progeria supports my argument as much as yours.

A recent cover story in one of the newspapers I read had a picture of a 10-year old boy with the condition. He was bald, wore reading glasses, and generally looked much older than his age. But his face did not look middle-aged. Why didn’t it, if his internal processes (the increase in entropy, if you will) had already advanced to the point of a typical 60-year old?

Well, one possible reason is that he couldn’t possibly have spent 60 years in the sun in only 10 years.