06 February 2006

Suspended Animation--Will it give Terminal Patients more Time?

Animal hibernation has long fascinated humans. Recently, scientists have begun to look into the possibility that humans might be able to use hibernation as a way to cheat death. Persons suffering from terminal illness such as cancer, might choose hibernation--to wait in suspended animation for a cure for their disease. Where is the science now?

From rxpgnews.com comes a story about hibernation, and a metabolic switch that triggers a state of torpor. Researchers at the UT Houston School of Medicine exposed mice to total darkness to look for the metabolic switch that mediates darkness-induced hibernation.

A series of experiments pinpointed 5-prime adenosine monophosphate (5'-AMP) as the key molecular mediator of the constant darkness effect, switching mice from a glucose-burning, fat-storing state to a fat-burning, glucose-conserving lethargy.

Active mammals – a bear foraging for food or a human running a marathon – also undergo a similar switch, burning glucose first to fuel their efforts, and as blood sugar is consumed, their bodies switch to burning fat.

"How does the body know when to switch? 5'-AMP is the signal. I believe it's the same metabolic system, whether we are talking about hibernation or not," said senior author Cheng Chi Lee, Ph.D., professor of biochemistry.

The team started with a basic question: What actually sets off hibernation? "These animals dig deep burrows," said Lee, an expert in circadian rhythms. "They are constantly in the dark. Why not darkness as a switch?"
This research was published in 19 Jan 2006 Nature.

Previous research used hydrogen sulfide and carbon monoxide as hibernation triggers in mice. Another known hibernation trigger in animals is an opioid like substance known as HIT, hibernation inducement trigger.

Cryonics is yet another approach to suspended animation. Freezing mature human cells produces irreparable damage. That may be a solvable problem. Human sperm, human ova, and human embryos are all frozen without damage. Why not adult humans?

What if people could choose suspended animation without any risk? How would society react to that choice? In welfare state societies, with cradle to grave social supports, the extra cost of supporting millions of people in hibernation might tip the economic balance. But if only the wealthy are able to go into a suspended state, to await a cure for terminal disease, how will the lower tiers react?

Biotechnology is not an ethereal, disconnected cognitive exercise. Every exciting discovery has long term repercussions. The future is not for the timid.

Update: Acceleratingtechnology.com points to this Sydney Morning Herald article about MGH Boston surgeon Hasan Alam, who continues to develop a method of inducing profound hypothermia, using pigs.

First he anaesthetises the animal, then cuts a major vein and artery in its abdomen to simulate multiple gunshots to a person's chest and abdomen.
As the pig rapidly loses about half its blood and enters a state of shock, Dr Alam drains its blood and stores it before pumping chilled organ preservation fluid into its system.

The animal's body temperature falls to about 10C until it is in a state of "profound hypothermia" and has no pulse and no electrical activity in its brain.

But after the blood stored earlier is warmed and pumped back into the pig's body its heart starts beating again and it comes back to life.

"It is still pretty awe-inspiring," Dr Alam said. "Once the heart starts beating and the blood starts pumping, voila, you've got another animal that's come back from the other side.

"Technically, I think we can do it in humans."

Dr. Alam is attempting to gain permission to use the technique in human patients who are so critically injured that they would certainly die without this type of heroic intervention. I would not want to be on the ethics committee of Mass General, dealing with this request. Most bioethicists who try to run such committees are not sufficiently seasoned in the real life and death world of trauma medicine, to understand such situations, where seconds can count. Read the entire article and think whether you would approve the procedure.


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