[Histonet] RE: Prion Contamination

[Bartlett, Jeanine (CDC/CCID/NCZVED)]

All,

The formic acid is a post-fixation step.

 
http://www.cdc.gov/od/ohs/biosfty/bmbl4/bmbl4s7d.htm#Table%205.%20Tissue
%20preparation


Jeanine Bartlett, BS, HT(ASCP)QIHC
Centers for Disease Control and Prevention
Infectious Diseases Pathology Branch
1600 Clifton Road, MS/G-32
18/SB-114
Atlanta, GA  30333
(404) 639-3590 
jeanine.bartlett <@t> cdc.hhs.gov


-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of joelle
weaver
Sent: Thursday, January 22, 2009 6:46 PM
To: sallen <@t> exchange.hsc.mb.ca; Histonet
Subject: RE: [Histonet] RE: Prion Contamination


I just researched this recently for procedure writing. I referenced an
article from the CDC that made mention of specific handling guidelines
for histology, and also specifically the formic acid treatment step. I
do not have the article in front of me, but by my recollection I believe
that it stated that the formic acid was a post-fixation step. I found
this article relatively easily by using the search field for CJD from
the CDC website. You can check my recollection here:
http://www.cdc.gov/od/ohs/biosfty/bmbl5/sections/SectionVIIIH-PrionDisea
ses.pdf
Thanks
Joelle Weaver HTL(ASCP)
> Date: Thu, 22 Jan 2009 13:21:25 -0600> From: 
> SAllen <@t> exchange.hsc.mb.ca> To: tbraud <@t> holyredeemer.com> Subject: 
> [Histonet] RE: Prion Contamination> CC: 
> histonet <@t> lists.utsouthwestern.edu> > Hi,> I was reading your email of 
> Jan. 15/09 on the subject of "Prion> Contamination". In it you had 
> made the following statement, which I was> curious as to where this 
> information had come from. > "the procedure to inactivate using formic

> acid is followed before> fixation and processing. If the tissue is 
> fixed (formalin or other> common fixatives) then you would be actually

> "fixing" the prion's> ability to NOT be inactivated". > I had read 
> again the WHO Guidelines on CJD that you had a link to &> could find 
> no mention of the fact that the formic acid step for> de-activating 
> the prions had to be done before any fixation. The WHO> instructions: 
> P. 18 8.2.2 Histopathological examination: states "formic> acid 
> treatment consists of placing small pieces of fixed tissue, no more> 
> than 4 to 5 mm thick, in 50 to 100 ml of 95% formic acid for an hour".

> I> have been dealing with CJD brains for many years always following 
> the> CDC, WHO & Health Canada guidelines but have never read any 
> studies that> had indicated that the fixing in formalin made the 
> treatment in formic> acid ineffective. If you have any further 
> information I would really> appreciate seeing it. > Thank you > S. 
> Allen> sallen <@t> hsc.mb.ca> >
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