Chemical fixation

Chemical fixation

Joined: October 11th, 2005, 9:18 pm

February 5th, 2009, 7:07 pm #1

I believe combining chemical fixation with cryopreservation was Mike's idea. It seems like an obvious idea. Two very common protocols in brain banking.

I think chemical fixation would help significantly to preserve information in today's climate. We have deplorable remote care capabilities. This is followed by slow transportation methods and non-professional care at the cryonics facility. A better option might be to get started on chemical fixation before shipping. A funeral director could be instructed to do a washout as gently as possible followed by standard embalming fluid.

We will assume that in most cases, the above procedure would destroy some vasculature and leave blood clots in some areas. But this would also be the case for stroke or accident victims. Once back at the cryonics facility, an large opening would be made in the skull, and more fixative added. After a few weeks/months, cryoprotectant would be introduced to gradually replace the water. Perfusion would be the primary means of introducing the cryoprotectant, but needle injection could significantly supplement perfusion in damaged areas. Many months could be allowed for thorough diffusion of cryoprotectants.

Advantages of the above protocol would be:
1. Much less technique sensitive.
2. Less time pressure.
3. Less equipment needed in the field.
4. Would equally help accident and stroke victims.
5. Would help in cases where delays happened.
6. Would help in underfunded situations. Gives people time to gather funds. Even years.

There have been very few ideal cases where the information preserved has been superior to what would have been preserved by using fixative first. And information preservation is what it's all about, not tissue viability.
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Joined: November 1st, 2007, 4:06 am

February 6th, 2009, 2:19 am #2

It sound like something that should be investigated. Would such a procedure cause the capillaries go into spasm?
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Joined: October 11th, 2005, 9:18 pm

February 6th, 2009, 3:17 am #3

Dr. Fahy reported that it increased freezing damage. But we don't freeze anymore, we vitrify.

No, it would definitely not cause capillary spasm. Once fixative hits tissue, the cells die and all function ceases. The capillary walls would not be capable of muscle contraction. Or did I misunderstand your question?
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Joined: November 1st, 2007, 4:06 am

February 6th, 2009, 3:37 am #4

It depends on how fast the fixative reaches the capillary. At first a diluted fixative will reach the capillary and that will cause spasm. A wave front so to speak. One could overcome this by first circulating a chemical that relaxes the muscle.
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Joined: October 11th, 2005, 9:18 pm

February 7th, 2009, 11:16 pm #5

I believe combining chemical fixation with cryopreservation was Mike's idea. It seems like an obvious idea. Two very common protocols in brain banking.

I think chemical fixation would help significantly to preserve information in today's climate. We have deplorable remote care capabilities. This is followed by slow transportation methods and non-professional care at the cryonics facility. A better option might be to get started on chemical fixation before shipping. A funeral director could be instructed to do a washout as gently as possible followed by standard embalming fluid.

We will assume that in most cases, the above procedure would destroy some vasculature and leave blood clots in some areas. But this would also be the case for stroke or accident victims. Once back at the cryonics facility, an large opening would be made in the skull, and more fixative added. After a few weeks/months, cryoprotectant would be introduced to gradually replace the water. Perfusion would be the primary means of introducing the cryoprotectant, but needle injection could significantly supplement perfusion in damaged areas. Many months could be allowed for thorough diffusion of cryoprotectants.

Advantages of the above protocol would be:
1. Much less technique sensitive.
2. Less time pressure.
3. Less equipment needed in the field.
4. Would equally help accident and stroke victims.
5. Would help in cases where delays happened.
6. Would help in underfunded situations. Gives people time to gather funds. Even years.

There have been very few ideal cases where the information preserved has been superior to what would have been preserved by using fixative first. And information preservation is what it's all about, not tissue viability.
I'm not just thinking out loud. I am seriously proposing this for Oregon. I have been moving in this direction for quite a while. It becomes most important in underfunded situations. Bill O'Rights, for example. Underfunded patients will only become more and more common. Others have finally convinced me that under no circumstances should an underfunded patient be placed in liquid nitrogen. So this latest proposal solves that issue by introducing chemical fixation as the short-term solution. It even means that we would not have to turn anyone away because we could always resort to chemical fixation as the long-term solution. As Bob Ettinger has sensibly reminded us, something is better than nothing. And chemical fixation will preserve a very significant amount of information even without subsequent vitrification.
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Joined: October 2nd, 2004, 8:27 pm

February 8th, 2009, 6:24 am #6

You said "Others have finally convinced me that under no circumstances should an underfunded patient be placed in liquid nitrogen."

Who others, Jordan?

If one of them was me, it had only to do with the fee required, sometimes very excessive, and that it was sometimes overlooked for celebs and such...

Cheers,

FD


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Joined: October 11th, 2005, 9:18 pm

February 8th, 2009, 4:26 pm #7

I would say everyone except you up to this point has been emphatic that pay-as-you-go is a highly flawed approach to cryonics and will lead to dire consequences. They object to accepting someone and allowing relatives to pay the ongoing costs. My response has always been that I have no problem removing someone from liquid nitrogen who fails to pay their bills. And it's at this point that they raise all sorts of ethical objections. My opinion has not changed, but consensus is very important to me.
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Joined: October 11th, 2006, 4:20 am

February 8th, 2009, 4:30 pm #8

from the Alcor FAQ:Q: Why not chemical fixation instead of cryopreservation?

A: Chemical fixation with cross-linking agents can stabilize biological structure for long periods of time in the liquid state, and it is reversible in principle with molecular nanotechnology. In fact, the cryonics chapter in Eric Drexler's book Engines of Creation discusses using a combination of fixation and vitrification for cryonics patients. However, there are concerns with this approach.

Fixation and storage at ambient temperature has sometimes been proposed as a low-maintenance version of cryonics. This approach is biologically inferior to good cryopreservation for several reasons. First, good chemical fixation is hard to do, and requires multiple agents to effectively preserve all major cell components. Some of these agents are expensive and extremely hazardous chemicals. Any imperfections in fixation would result in decaying tissue, whereas defects in cryoprotective perfusion during cryopreservation only result in tissue freezing rather vitrifying; a limited degree of damage that ends with stability. Second, even the best fixation methods only stabilize a subset of biological molecules by attaching to certain points on the molecules. In contrast, cryopreservation by vitrification provides guaranteed stabilization of every molecule present by turning the whole system solid. Finally, because vitrification is based on solutions and procedures developed for preservation and recovery of living tissue, tissue preserved using state-of-the-art vitrification solutions are intrinsically closer to viability, and normal biological condition, than tissue preserved using techniques developed for histological endpoints.
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Joined: October 11th, 2005, 9:18 pm

February 8th, 2009, 5:40 pm #9

"First, good chemical fixation is hard to do"
No, it can be as simple as soaking in fixative. http://www.depressedmetabolism.com/2007 ... ale-brains/

"requires multiple agents to effectively preserve all major cell components"
No it doesn't. Two agents, formaldehyde and gluteraldehyde are more than adequate. It's a common mixture.

"Some of these agents are expensive and extremely hazardous chemicals"
Like Osmium Tetroxide. Yes, but that is not a necessary agent. It's useful for visualizing lipids, but it's not needed to preserve them.

"Any imperfections in fixation would result in decaying tissue"
The whale brain wasn't even perfused, it was just immersed. And even then, very few areas showed the beginning signs of "decaying tissue".

"even the best fixation methods only stabilize a subset of biological molecules by attaching to certain points on the molecules"
Nearly all molecules are stabilized with aldehydes. Yes, even lipids.

"intrinsically closer to viability"
Completely irrelevant. Information preservation is our goal, not viability.

I'm in a hurry, so I didn't post references. I might do that when I have more time.


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Joined: October 6th, 2004, 6:46 pm

February 8th, 2009, 5:47 pm #10

I believe combining chemical fixation with cryopreservation was Mike's idea. It seems like an obvious idea. Two very common protocols in brain banking.

I think chemical fixation would help significantly to preserve information in today's climate. We have deplorable remote care capabilities. This is followed by slow transportation methods and non-professional care at the cryonics facility. A better option might be to get started on chemical fixation before shipping. A funeral director could be instructed to do a washout as gently as possible followed by standard embalming fluid.

We will assume that in most cases, the above procedure would destroy some vasculature and leave blood clots in some areas. But this would also be the case for stroke or accident victims. Once back at the cryonics facility, an large opening would be made in the skull, and more fixative added. After a few weeks/months, cryoprotectant would be introduced to gradually replace the water. Perfusion would be the primary means of introducing the cryoprotectant, but needle injection could significantly supplement perfusion in damaged areas. Many months could be allowed for thorough diffusion of cryoprotectants.

Advantages of the above protocol would be:
1. Much less technique sensitive.
2. Less time pressure.
3. Less equipment needed in the field.
4. Would equally help accident and stroke victims.
5. Would help in cases where delays happened.
6. Would help in underfunded situations. Gives people time to gather funds. Even years.

There have been very few ideal cases where the information preserved has been superior to what would have been preserved by using fixative first. And information preservation is what it's all about, not tissue viability.
In computers, the chip loses the memory its holding when the power is removed. A disc drive writes data to media for storage, and can survive the power being off and on.
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