Re: Mad Cow Implications for Cryos

Date: Wed May 16 2001 - 15:37:45 MDT

In a message dated 5/16/01 1:55:04 PM, cites

>The studies undermine hopes that the 100 or so victims to date of variant
>Creutzfeld Jakob Disease (vCJD) only succumbed to the disease because of
>freak variations in one key gene.

That's a straw man. 1/3 of the population carries the gene in question.
Only 100 of ~ 20,000,000 susceptible English has gotten it, and the
incidence curve has leveled off. Even if the whole population started
catching it like the susceptibles, risks would be well below societally
catastrophic - 1 in a few thousand, tops. Enough to justify personal concern,
but no panic. Naturally people working on vCJD have an incentive to
magnify the risks of vCJD (not to dismiss the valid level of concern
with vCJD)

>The new work suggests the time it takes to develop the disease might depend
>on a combination of several genes, not just one. This means that far greater
>numbers of us could be "incubating" the disease, but have yet to show

Greater, perhaps, but the idea of "most" doesn't fly. Prion diseases have a
definite dosage requirement to catch them at all*. It is, of course, possible
that humans are unusually susceptible to catching BSE and unusually slow
to develop it; but that remains a low probability event.

*Technically it appears each prion molecules has a very low chance of xmitting
disease and a very high chance of leaving the target completely unaffected.
Any given dose has a probability of not affecting the target, period.
You need a reasonably high titer to have a significant chance of catching the
disease. For x-species transmission by oral routes the titers are very high.

>So, does anyone know if the prion disease will continue to ravage the brain
>even when submerged in LN2 (or at the proposed, somewhat warmer storage

No ongoing effects. The prion proteins have to move around to encounter the
normal ones and convert them. At all proposed storage temperatures,
everything is hard-frozen and nothing's going anywhere.

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