X-Message-Number: 13865
Date: Wed, 07 Jun 2000 22:58:19 -0700
From: Mike Perry <>
Subject: Hi-temp storage, calore restriction, FTL

Ivan Snyder, #13850, says
>Considering the freezing point of glycerol, it seems to me that immersion
>in liquid nitrogen defeats the purpose.

Not so. You are trying mainly to preserve inferable structure, not cell
viability, unlike what nature is "trying" to do.

> I imagine that the vitrification
>process is meant to get around this, but I understand that the chemicals
>involved are toxic.

Work is being done to reduce toxicity.

> I see a benefit in the use of liquid nitrogen; the
>system is more easily maintained, less fear of breakdown, and is cheaper
>than with a refrigerator. Still, temperatures regulated by a refrigerator
>at -20 most closely matches the natural *working* cryosuspension systems
>seen in the insects.

There is no prospect presently known for longterm storage of brain tissue at
-20. Suda found significant degradation of brain waves after storage of up
to 7 years. (That he got brainwaves at all after such a long time is
remarkable though.) This would not rule out some new protocol that would
lead to viable storage at this temperature, but it has yet to be worked out.
Once again, our goals are not identical to nature's, and we can't simply
trust nature to provide the answers.

> These seem like good reasons for re-examining

Looking for better protocols is certainly worthwhile, but I think it would
be a mistake to fixate too strongly on systems in which the organism is
still slightly metabolizing, which is probably true at -20. Again, though, I
am not ruling out a high-temperature protocol. There is certainly much in
this area that we do not know.

On the subject of calorie restriction (Doug Skrecky, #13853) this subject
has come up before. I am not an expert, but I had to deal with it as part of
the book I've written, which I hope to send off to a publisher (finally) in
maybe a day or two. I ended up echoing the sentiments of advocates of CR, at
least to the extent that it appears to have some beneficial effect and does
tend to increase the lifespan when tested in lab animals, though its precise
mechanism is unknown. The paper Doug cites does not appear to challenge that
conclusion, only to suggest that certain observable changes in the skin of
mice correlate well with life expectancies. It could certainly be the case
that the lifespan increase is entirely due to the poor diets the lab mice
have been exposed to, but this must be so for many, many experiments over
the several decades that CR has been studied. I'm sure many diets were
tried, and to me it seems unlikely that all of the observed increases in
lifespan can be attributed entirely to poor food. Doug also says "Obesity
also has no effect on mortality, provided physically fit obese humans are
compared with physically fit lean humans." Well, as long as you are
physically fit you aren't about to die (except for accidents, etc.). But the
question can still can be raised whether obese people are as  likely to *be*
physically fit, and stay that way, as lean people. In any case, based on the
previous debates on this forum my book now says "when effects of disease are
accounted for, thinner people with adequate nutrition are longer-lived." A
reference I was given on this is: NIH National Task Force on the Prevention
of Obesity, "Very Low-Calorie Diets," JAMA 270 #8 (1993) 967-74.

On faster-than-light travel and signalling (James Swayze, #13851) I think it
is still holding up that no information can actually be sent and understood
at the other end in time less than it would take light to travel the
distance, and this I see as basically upholding relativity even if funny
effects persist. (I like it that an object can be in two places at once
though--shades of many-worlds!) 

 Mike Perry

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