X-Message-Number: 5105
Date:  Sat, 04 Nov 95 13:55:58 
From: mike <>
Subject: SCI.CRYONICS dendritic spines update

Dendritic Spines: Review and Update 
by Mike Perry 
 
A posting of Doug Skrecky [1] on Sept. 14 states that, 
"Lowering temperature is an ineffective means for 
preserving bodily structures. After death brain structures in 
particular are rapidily degraded. Even at 4 degrees C after 
blood flow is interrupted to the brain almost 50% of 
dendrite spines are destroyed within 4 hours. After 24 
hours this figure rises to 74%. Fortunately only 4% are lost 
over the first 45 minutes post mortem_probably because it 
takes a while for brain cells to die." [2] Needless to say all 
this, if substantiated, would signal major worries for 
cryonics. Patients often are stored for many hours at near-
freezing temperature, before freezing can start. 
 
Dendritic spines are tiny outgrowths of the dendrites of a 
neuron in the brain that form synaptic junctions with axons. 
The axons in turn carry signals from other neurons, so the 
synapses are the vital communication link between the 
neurons that enable the brain to function. Loss of dendritic 
spines has been observed in senile dementias such as 
Alzheimer's disease [3] and appears to be a factor in the 
substantial loss of memory and other mental deterioration 
that is seen. 
 
On first reading, the reference cited by Skrecky [2] appears 
to confirm that substantial degradation of dendritic spines 
was occurring, over 4 hours or less, at near-ice temperature. 
(The study was done with guinea-pigs stored for intervals 
ranging from 5 min. up to 24 hrs. postmortem. Brain tissue 
was then removed and prepared for microscopic 
examination, through fixation and staining, using one of 
the standard techniques.) I wrote an article, originally 
posted to CryoNet, which has now appeared elsewhere in 
different versions, raising doubts as to whether today's 
cryonics patients could be reanimated [4]. There has been a 
flurry of responses, the general consensus being that 
research into better cryonic techniques must continue, 
though we should not give up hope even for today's (and 
yesterday's) patients. 
 
Since then I've reviewed other literature (for which I thank 
Thomas Donaldson) which offers a rather different and 
more optimistic picture. It appears that the particular 
technique used to look at the tiny structures of the brain is 
crucially important in deciding which changes are 
occurring and in what amounts. The contention that 
"dendrite spines are destroyed" under the conditions and in 
the percentages recounted by Skrecky, is not warranted by 
the evidence that is presented. Instead it seems that the 
apparent degradation can be attributed to the preparation 
technique that was used, which is known as the rapid Golgi 
method. (This does not mean that destruction of the spines 
or other structures is precluded, just that the spine counts 
do not give a reliable indicator of how much retention and 
loss is actually occurring.) An alternative technique, the 
Golgi-Cox method (despite the similarity of names it is 
very different!) gives generally better results. A study has been 
done comparing the two methods [5]. I quote the abstract. 
 
"Comparisons were made between the results of applying 
the Golgi-Cox and rapid Golgi techniques to human brain 
tissue obtained at autopsy. Adjacent blocks of hippocampal 
formation and precentral gyrus [a brain convolution] from 
nine cases were prepared by the two methods. The cases 
ranged in age from 39 to 99 years, had postmortem times 
for sampling ranging from 6 to 28 hours (h) and included 
cases of dementia of the Alzheimer type. Without 
exception, the methods produced very different results. The 
Golgi-Cox method resulted in impregnation of many 
neurons with rich dendritic plexuses and normal overall 
appearance. Occasional cells appeared grossly atrophic 
with irregular somata and apparent loss of apical and 
basilar dendritic segments. With the rapid Golgi method, 
the vast majority of impregnated neurons exhibited such 
grossly atrophic appearances while few, if any, 
impregnated neurons had rich dendritic plexuses or were 
otherwise normal in appearance. Thus, the rapid Golgi 
method appears to be highly sensitive to postmortem delay 
or other factors which accompany studies involving human 
brain tissues obtained at autopsy. The Golgi-Cox method 
appears to be relatively insensitive to such factors." 
 
It's important to keep in mind that the two methods were 
applied to tissue from the same subject, taken under the 
same conditions (e.g. postmortem delay), and as nearly as 
possible identical. (The staining techniques, being 
irreversible, preclude using the same piece of tissue for 
both methods, but very similar, adjacent tissues were used.) 
When one method consistently shows preservation of a 
structure, even if, as here, the other shows degradation, it 
means *the structure must have been present* before either 
method was applied. These results are consistent with other 
findings such as the recent study by Mike Darwin et al. 
which reported good preservation of neuronal structures, 
including dendritic spines, with postmortem metabolic 
support and high-glycerol perfusion prior to freezing [6]. 
Good news, I'd say, for cryonics, provided as always we 
don't become too complacent. 
 
References: 
 
[1] Skrecky, D. "Biostasis," *Mensa Canada 
Communications* Jan-Feb 1991, reprinted in CryoNet 
message 4871 (14 Sep 1995). 
 
[2] de Ruiter, J. "The influence of post-mortem fixation on 
the reliability of the Golgi silver impregnation," *Brain 
Research* 6, 143 (1983). 
 
[3] de Ruiter, J. and H. Uylings, "Morphometric and 
dendritic analysis of fascia dentata granule cells in human 
aging and senile dementia," *Brain Research *402, 217 
(1987). 
 
[4] Perry, M. "Dendritic spines: a possible problem for 
cryonics," CryoNet message 4949 (10 Oct 1995). 
 
[5] Buell, S. "Golgi-Cox and rapid golgi methods as 
applied to autopsied human brain tissue: widely disparate 
results," *J. Neuropath. Exp. Neurol.* 41(5), 500 (Sep 
1982). 
 
[6] Darwin, M., S. Russell, L. Wood, C. Wood, and S. 
Harris. "Canine brain cryopreservation" BPI Tech. Brief 
#16, CryoNet messages 4468 and 4474 (1-2 Jul 1995).


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