[ExI] Another step towards uploading
johnkclark at gmail.com
Sun Oct 6 15:33:12 UTC 2013
On Sat, Oct 5, 2013 at 7:07 PM, Rafal Smigrodzki <rafal.smigrodzki at gmail.com
> The problem is that suspension usually takes place under non-optimal
> conditions - instead of live perfusion as in the case of animals used for
> the scans you mentioned, the cryonauts are treated typically after many
> hours of warm ischemia and this means the perfusion can be rather poor.
> Freezing here at least stops further damage. Keeping a poorly perfused
> brain at room temp makes it turn into a mush.
Apparently a way to overcome this problem was found just a few months ago:
Using an automated process a woman's brain was cut into 7400 slices 20
micrometers thick, a human hair is about 50 micrometers thick. Then they
mounted the slices on glass slides, stained them and took very high
resolution photographs that almost reached the cellular level. This is 50
times better resolution in all 3 directions than ever made of a human brain
before. I can't help but wonder if more information has been preserved
about this women, that is to say she has a better chance of resurrection,
than any current patient of Alcor. I'm not saying she does but I wonder.
> Max wrote about the choices between vitrification vs. fixation recently
> (or was it somebody else at Alcor?).
As far as I know the only thing Alcor has said about chemopreservation is
About a year ago I made some comments about some of its assertions, but I
received no response from Alcor concerning them:
> For example, the expensive and extremely toxic chemical osmium tetroxide
> is routinely used for stabilization of lipids in preparation for electron
If something as dangerous to handle and expensive as osmium tetroxide were
needed then that could be a show stopper for chemical fixation being a
alternative to cryonics, but I don't see why it would be needed. Osmium
tetroxide is primarily not a stabilizer but a stain, it works well as a
contrast agent in electron microscopes because heavy metals like Osmium
scatter lots of electrons. However how information is extracted from my 3
pounds of frozen or chemically fixed brain is not my problem it is the
problem of beings who live in a age of advanced Nanotechnology. My only
concern is that the information remains intact inside that 3 pounds of grey
goo, I don't know exactly how it will be extracted but I doubt it will be
by electron microscopes.
> Unlike the cryobiologist, the chemical fixation researcher cannot
> reverse fixation and test for viability.
I don't understand what is meant by that or what edge Cryonics has over
fixation because of it. Viability just means it works, and so far neither
Cryonics nor fixation has brought anybody back and I don't think anybody
will until advanced nanotechnology is developed. It almost sounds like
there is supposed to be some advantage in using the same atoms in the
reawakened being as in the old one, but I can't imagine what that advantage
> The cryobiologist does not have to confine himself to this fate because
> he can attempt to measure viability in the brain
Obviously during revival at every step you'd like to know if you're doing
it right and are on the right track, but again I don't see why cryonics
would be better at this than fixation.
> or even the whole organism.
Preserving any part of the body with either method except for the brain
seems completely pointless to me.
> Let us assume, for the sake of the argument, that the chemopreservation
> advocate has identified a number of fixatives (and other treatments) that
> are sufficient for complete ultrastructural preservation of the brain. The
> next question is going to be: how stable will chemopreservation be over
> time? This is a very important point for the technical feasibility of
Yes that is a important point. With Cryonics, unless we're talking about
millions of years and as long as things remain cold (but will it?), pretty
much all the damage that is going to be done has been done by the time the
brain reaches liquid nitrogen temperatures. And I'm not worried about
damage caused during thawing because that won't be done with existing
technology, assuming it's even thawed at all and it probably won't be; the
information will probably be read out by disassembling the brain from the
outside in while it remains in solid form.
I don't know if chemical fixation would remain as stable over the centuries
as freezing, my hunch is that cryonics has a small edge over fixation in
this regard but I could be dead wrong, maybe it's a big edge. And I don't
want to be dead.
> It is not only necessary to demonstrate that all chemicals can be
> introduced by perfusion fixation without perfusion artifacts
Both methods are imperfect so it is only necessary to demonstrate that
fixation produces fewer artifacts than Cryonics or that the artifacts
produced are easier to identify as artifacts to make it the superior
> In my opinion, the prospect of autolysis is much worse because when
> biomolecules break up into their constitutive parts, and go into solution,
True, but if fixation is done correctly there won't be any fluid for things
to move in.
> there is a risk that essential parts of the brain will not be fixed, as a
> result of inadequacies of the protocol, perfusion artifacts, or long term
> degradation. It is at this point where classic cryopreservation really
> shines. Even tissue that is not protected from ice formation as a
> consequence of perfusion impairment will still be "fixed" through low
That is another very good point. If the cryo-preservative doesn't reach a
certain part of the brain things might not be hopeless because at least it
still gets frozen so you still might be able to get information out of it
if your technology is good enough, but if the chemical fixative doesn't
reach part of the brain things are far far more serious.
But the smaller the biological sample you're trying to infuse with
cryo-preservative or chemical fixative the easier it is, so both methods
might be improved if before any chemical was infused or any freezing done a
dozen or so thin cuts were made to slice the brain into smaller pieces. The
cuts could be made very thin indeed, 30 nanometers or about 100 atoms
thick. Yes you would be destroying some tissue but if the technology is
good enough to repair all the damage caused by freezing or chemical
fixation then I don't think they'd have much trouble figuring out what is
supposed to be in that very narrow gap.
> [...] there is little hope of inferring the original structure of the
Yes, the important thing is that things stay put, or at least if they must
move the flow should not be turbulent so you can figure out where the parts
were before they moved. If things are turbulent then a small change in
initial conditions will lead to a huge change in out come and you'll never
figure out where things are supposed to go. I don't see why turbulence
would occur in chemical fixation and fortunately (see below) it doesn't
look like it would happen during the freezing of a brain either (I'm not
interested in what happens during unfreezing, that's a problem for advanced
nanotechnology, I just want to be sure the information is still inside that
frozen lump of tissue). That's why I think Cryonics has a pretty good
chance of working at least from a technical viewpoint, whether the brain
will actually remain at liquid nitrogen temperatures until the age of
nanotechnology and whether anybody will think we're worth the bother of
reviving is a entirely different question.
Fluid flow stops being smoothly Laminar and starts to become chaotically
turbulent when a system has a Reynolds number between 2300 and 4000,
although you might get some non chaotic vortices if it is bigger than 30.
We can find the approximate Reynolds number by using the formula LDV/N. L
is the characteristic size we're interested in, we're interested in cells
so L is about 10^-6 meter. D is the density of water, 10^3 kilograms/cubic
meter. V is the velocity of the flow, during freezing it's probably less
than 10^-3 meters per second but let's be conservative, I'll give you 3
orders of magnitude and call V 1 meter per second. N is the viscosity of
water, at room temperature N is 0.001 newton-second/meter^2, it would be
less than that when things get cold and even less when water is mixed with
glycerol as it is in cryonics but let's be conservative again and ignore
those factors. If you plug these numbers into the formula you get a
Reynolds number of about 1. 1 is a lot less than 2300 so it looks like any
mixing caused by freezing would probably be laminar not turbulent, so you
can still deduce the position where things are supposed to be.
John K Clark
> This said, one of my greatest worries regarding suspension is
> organizational failure at Alcor - could happen during civil war, major
> economic downturn or even due to mismanagement (not to say that the current
> team is likely to fail but rather, you can never trust the younger
> generations to stay faithful to the ideas of their predecessors). If I
> could have elective live perfusion while still fully functional, followed
> by polymer embedding (this might require some technology development ) and
> room temperature storage, I might prefer it over cryoprotectant and helium
> persufflation. I'm assuming that nanoscale MRI would still work in polymer
> embedded tissue, so there would be no need for heavy metal staining.
> I do think that both approaches, vitrification and fixation, should
> be further researched, as much as our limited resources allow but for
> now vitrification is still the better way to go.
> Rafal Smigrodzki, MD-PhD
> Senior Scientist,
> Gencia Corporation
> 706 B Forest St.
> Charlottesville, VA 22903
> tel: (434) 295-4800
> fax: (434) 295-4951
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