[Histonet] RE: Prion Contamination

[joelle weaver]

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-PrionDiseases.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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