X-Message-Number: 5829
From: (Brian Wowk)
Newsgroups: sci.cryonics,sci.life-extension,uk.legal
Subject: Re: Death (was Donaldson MR and Miss Hindley)
Date: 23 Feb 96 23:22:36 GMT
Message-ID: <>
References: <> <>
In <> Marshall Rice <>
writes:
>I think you will find that it was you who first attempted to dazzle us with
>a discourse on a subject of which you know nothing, in pontificating
>on the mechanism and consequences of tissue damage by ionising radiations.
>I see that you have now conveniently steered round that awkward little
>subject and your own glaring misconceptions and are heading away from it at
>full speed.
>I ask again, and this time let me spell it out, what IS the qualification
>in "medical physics" that you chose to flaunt, what is your area of
>expertise and what precautions do you take to protect your cadavers from
>the effects of ionizing radiations?
I have answered all these questions in reply to your earlier post.
If that post did not reach your site yet, please say so and I'll repost.
>> We are apparently to believe that after three minutes of
>> (warm?) ischemia, the brain undergoes a magical transition called
>> "death" which is accompanied by the immediate and total disintegration
>> of its constituent cells into jumbled atoms and molecules....
>Since you chose to quote it earlier, I suggest you read my posting again.
>I neither said nor implied that tissue death is instantaneous, merely
>that it is irreversible.
...after three minutes. And this is nonsense. Obviously at SOME
time after onset of cardiac arrest, brain injury will become irreversible
by ANY conceivable technology. But three minutes certainly isn't it.
Three HOURS (or more) is probably closer to the truth.
>You raise another interesting point, though, even if inadvertantly. Can
>you tell us what you know of the ion pump mechanism, and in what sense its
>failure is "mere"?
After about three minutes of cerebral ischemia, ATP stores become
depleted, and the ion pumps that keep calcium and sodium from entering
cells run out of fuel. The result is a massive influx of these unwanted
ions into cells, and cell swelling. Cell swelling then constricts the
capillaries, ultimately preventing the resumption of brain blood flow
after the heart is restarted. This (in very simplistic terms) is why
doctors find it so hard to resuscitate people after a few minutes of
cerebral ischemia.
30 years ago, Hossman and Sato showed that cats could be revived
after ONE HOUR of global cerebral ischemia if blood was reperfused at
very high pressures (overcoming the capillary swelling). In the 1980's
White and others showed that calcium channel blockers could substantially
extend the "resuscitation window" for cardiac arrest victims. In one
anecdotal case, reported in Medical World News, a young stabbing victim
was successfully resuscitated after ONE HOUR of cardiac arrest with the
aid of calcium blockers. (An additional mitigating factor in this case may
be that the victim completely exsanguinated from his wounds, preventing
the immune/inflammatory cascade and blood clots that are additional
problems associated with cerebral ischemia.)
So where is this "death" that occurs after three minutes?
Although blood flow restoration becomes problematic after three minutes
for reasons stated above, there is NOT A SINGLE CELL in the brain that
is "dead" after three minutes. In reality, cerebral ischemic injury
is an extremely complete PROCESS, not an event. The more detail with
which you look at this process, the further "death" retreats into
the foggy distance. What we see is *chemistry* (some easy to reverse,
some difficult), but no vanishing of any vital force or metaphysical
event called "death".
If you really want to know what happens to the brain when blood
circulation stops, check out
http:/www.cryocare.org/cryocare/bpi/tech4.txt
Just what are the ultimate limits of cerebral resuscitation if
we could perform repairs at the molecular level? Within the document
below
http:/www.cryocare.org/cryocare/casecryo.txt
you will find references to studies where brain cells show metabolic
activity ("life" in vitalist terminology) even when extracted from
cadavers HOURS after clinical death. In one study, living, functioning
synaptosomes (the "business end" of neurons) are recovered 24 HOURS(!)
after death.
Marshall, you are obviously a very well educated and intelligent
man. I have however thus far found many of your criticisms of cryonics
to be long on popular mythology and short on facts. They have been of
the form
<erroneous fact stated with certainty>
<pejorative disparagement of cryonics>
I apologize for my occasional sarcasm, but surely you see that the
format above essentially says, "Flame me, please!" I promise to
keep my discussion on more professional and friendly level henceforce
if you will agree to do the same.
**************************************************************************
Brian Wowk CryoCare Foundation 1-800-TOP-CARE
President Your Gateway to the Future
http://www.cryocare.org/cryocare/
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