X-Message-Number: 2484
From: Ralph Merkle <>
Subject: CRYONICS  Re: Brain Injury
Date: 	Fri, 10 Dec 1993 11:55:39 PST


>From "The Technical Feasibility of Cryonics" by Ralph C. Merkle,
extended version:

Temporary and sometimes even permanent functional recovery has been
demonstrated in optimal situations after as long as 60 minutes of
total ischemia[93, 94, 95].  Hossmann, for example, reported results
on 143 cats subjected to one hour of normothermic global brain
ischemia[97].  "Body temperature was maintained at 36 degrees to
37 degrees C with a heating pad. ... Completeness of ischemia was
tested by injecting Xe 133 into the innominate artery immediately
before vascular occlusion and monitoring the absence of decay of
radioactivity from the head during ischemia, using external
scintillation detectors. ...  In 50% of the animals, even major
spontaneous EEG activity returned after ischemia....  One cat survived
for 1 yr after one hour of normothermic cerebrocirculatory arrest with
no electrophysiologic deficit and with only minor neurologic and
morphologic disturbances."  Functional recovery is a more stringent
criterion than the more relaxed information theoretic criterion, which
merely requires adequate structural preservation to allow inference
about the pre-existing structure.  Reliable identification of the
various cellular structures is possible hours (and sometimes even days)
later.  Detailed descriptions of ischemia and its time course[72, page
209 et sequitur] also clearly show that cooling substantially slows the
rate of deterioration.  Thus, even moderate cooling "postmortem" slows
deterioration significantly.

72.     "Cell Death in Biology and Pathology" edited by I. D. Bowen and R.
A. Lockshin, Chapman and Hall, 1981.

97.     "Resuscitation potentials after prolonged global cerebral ischemia
in cats" by Konstantin-Alexander Hossmann, MD, Ph.D., Critical Care
Medicine, Vol 16, No. 10, 1988, page 964-971.

Other references of interest:

93.     "Neurochemical Determinants of Ischemic Cell Damage" by Carl-
Henrik Nordstrom, M.D. and Bo K. Siesjo, M.D., pages 49-66; from
"Protection of the Brain from Ischemia" edited by Philip R. Weinstein
and Alan A. Faden, Williams and Wilkens 1990.

94.     "Hemodynamics of Postischemic Reperfusion of the Brain," by K.-A.
Hossmann, M.D., Ph.D., pages 21-36; from "Protection of the Brain from
Ischemia" edited by Philip R. Weinstein and Alan A. Faden, Williams and
Wilkens 1990.

95.     "Post-ischemic resuscitation of the brain:  selective
vulnerability versus global resistance" by K.-A. Hossman; from Progress
in Brain Research, Vol. 63, edited by K. Kogure, K.-A. Hossman, B. K.
Siesjo and F. A. Welsh, 1985, pages 3-17.

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