X-Message-Number: 33316
Date: Sun, 6 Feb 2011 13:42:44 -0800 (PST)
From: 
Subject: an odd idea - fixation for cryonics?

We assume that brain cells must be alive in order to store
memories. Formaldehyde fixation is indeed highly destructive of the
molecular basis of memory. However ethanol fixation apparently is
not. Ethanol fixation may be compatible with cryonics, particularly since
ethanol is also an effective cryoprotectant. Ethanol fixation would only
be the treatment of last resort for political jurisdictions that ban or
are otherwise hostile to cryonics. It would be superior to a straight
freeze with no perfusion at all, since a straight freeze destroys the
viability AND the morphology of brain cells, resulting in complete
obliteration of the physical basis of memory.

Brain Pathol. 2004 Apr;14(2):175-82.

Comparison of ethanol versus formalin fixation on preservation of histology and 
RNA in laser capture microdissected brain tissues.

Su JM, Perlaky L, Li XN, Leung HC, Antalffy B, Armstrong D, Lau CC. Laboratory 
of Molecular Neuro-oncology, Cancer Genomics Program, Texas Children's Cancer 
Center, Houston, Tex., USA.
Abstract

  Although RNA can be retrieved from formalin-fixed, paraffin-embedded (FFPE) 
  tissues, the yield is low, and the RNA is fragmented. Recent advances in gene 
  expression profiling underscore the importance of identifying a fixative that 
  preserves histology and mRNA. We demonstrated that, for immersion fixation of 
  brains, 70% ethanol is superior to formalin for mRNA preservation. RNA yield 
  from ethanol-fixed tissues was 70% of the yield from fresh frozen specimens, 
  but only a negligible quantity was recovered from formalin-fixed tissues. RNA 
  from ethanol-fixed brains showed integrity comparable to RNA from fresh frozen
  tissues, and RT-PCR using RNA from ethanol-fixed tissues was consistently 
  successful. RNA from FFPE tissues composed of low-molecular weight fragments, 
  and their use in RT-PCR failed repeatedly. The yield and quality of RNA from 
  ethanol-fixed brains were unaffected after immersion at 4 degrees C for 2 
  weeks. In a blinded comparison to FFPE tissues, ethanol-fixed specimens were 
  judged to show comparable histology and superior immunostaining. After laser 
  capture microdissection (LCM), we failed to recover mRNA from FFPE tissues but
  retrieved mRNA from ethanol-fixed tissues for RT-PCR and cDNA microarray 
  analysis. We conclude that 70% ethanol preserves RNA integrity and is suitable
  for expression profiling of brain tissues by LCM and cDNA microarray.
PMID: 15193030

Hippocampus. 2010 May;20(5):584-95.

>From learning to forgetting: behavioral, circuitry, and molecular properties 
define the different functional states of the recognition memory trace.

Romero-Granados R, Fontan-Lozano A, Delgado-Garcia JM, Carrion AM. Division de 
Neurociencias, Universidad Pablo de Olavide de Sevilla, Carretera de Utrera, Km.
1, 41013-Sevilla, Spain.
Abstract

  Neuropsychological analyses of amnesic patients, as well as lesion 
  experiments, indicate that the temporal lobe is essential for the encoding, 
  storage, and expression of object recognition memory (ORM). However, temporal 
  lobe structures directly involved in the consolidation and reconsolidation of 
  these memories are not yet well-defined. We report here that systemic 
  administration of a protein synthesis inhibitor before or up to 4 h after 
  training or reactivation sessions impairs consolidation and reconsolidation of
  ORM, without affecting short-term memory. We have also observed that ORM 
  reconsolidation is sensitive to protein synthesis inhibition, independently of
  the ORM trace age. Using bdnf and egr-1 gene expression analysis, we defined 
  temporal lobe areas related to consolidation and reconsolidation of ORM. 
  Training and reactivation 21 days after ORM acquisition sessions provoked 
  changes in bdnf mRNA in somatosensory, perirhinal, and hippocampal cortices. 
  Reactivation 2 days after the training session elicited changes in bdnf and 
  egr-1 mRNA in entorhinal and prefrontal cortices, while reactivation 9 days 
  post-training provoked an increase in egr-1 transcription in somatosensory and
  entorhinal cortices. The differences in activated circuits and in the 
  capacity to recall the memory trace after 9 or 21 days post-training suggest 
  that memory trace suffers functional changes in this period of time. All these
  results indicate that the functional state of the recognition memory trace, 
  from acquisition to forgetting, can be specifically defined by behavioral, 
  circuitry, and molecular properties.
2009 Wiley-Liss, Inc.
PMID: 19603520

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