"Robert J. Bradbury" wrote:
> There is one "catch" with humans however. We have not been engineered
> to operate well at low temperatures. Squirrels, turtles, bears, some fish,
> etc. have carefully tuned their genomes so their enzymes operate over
> a wider temperature range (or they have temperature dependent expression
> of the enzyme variants adapated to the different temperatures). I believe
> if you cool humans down too much the heart will stop beating.
I did not expect the heart to keep beating. It is the restart that is the trick, and worth studying if not for hibernation, then just to extend the rescue time for drowning victims.
> The other problem is that until you have relatively automated vital
> signs observations you probably shouldn't hibernate in anyplace but
> an intensive care unit. That makes it a pretty expensive nap.
Yes, I expect it would be at first. However, when relatively automated it would not take much to support large groups.
I envisioned people floating in chambers wearing something that looks like a wet suit, but works like a cross between a G-suit and a portable iron lung. Rhythmic pressure around the legs and arms alternates with pressure around the chest to circulate the blood (this presumes the individual still has operational heart valves), with periodic lung inflation. At very low metabolism, the need for blood flow is greatly reduced, and flotation makes the job much easier.
> Whether you could push metabolism down to 10% of normal is iffy.
> An interesting question would be whether you could lower the
> metabolism to hibernation levels *but* maintain the body at a
> more reasonable operating temperature (warm it from the outside
> in instead of the inside out).
That is certainly worth looking into. You would have to check to see that the kinds of things you are trying to avoid are all metabolism effects and not just temperature effects, or there would be no point.
> The decrease in metabolic activities cited above should retard
> most diseases as well. You might have to be careful about the
> bacteria in your gut. If they evolved variants that could be
> more active at a lower temperature or were more aggressive
> about invading your cells while your immune system was on
> standby, then you could be in a very bad situation. Remember,
> your body could be breakfast, lunch and dinner for the "parasites".
Yes, I thought about this as well. Some protozoa do quite well at low temperatures and if not prevented, you would be duck soup to them.
> Nanobots can target the cancer cells on the basis of temperature
> differences (and this is covered to some degree in Nanomedcine vol. 1).
Once there is MNT, there is no need for this or cryonics or just about anything I would design in the mean time.
Thank you for your comments.