Re: [Histonet] prions and frozen sections

From:Gayle Callis

Our laboratory is BSL2 for prion work, murine and hamster animal models - 
brain, spinal cord and other tissues.

A microtomy room is dedicated to prion work, and also contains a cryostat 
dedicated to prion work ONLY whether the tissus is fixed or not prior to 
cryomicrotomy.  There is no way we can totally, 100% decontaminate the 
cryostat for prions, BSL2 or not, and I have too many other people, 
including students and technicians working on another cryostat and have to 
worry about prion decontamination.   The researcher bought and maintains 
his own cryostat and hopefully it has a long life as no repairman would go 
inside it now.

For paraffin work (also cryostat), workers take the necessary precautions, 
gloves, safety glasses, disposable lab coats, etc. when sectioning paraffin 
blocks and frozen sections.  The microtome, waterbath are also dedicated to 
prion, nothing else is cut on these.

Water from waterbath is dumped into a carboy of 6N NaOH (sitting in a big 
tub to collect any spills) until it reaches a volume where the NaOH becomes 
2N simply by dilution, all is allowed to sit.  We used to use bleach, that 
has gone by the wayside in favor of the NaOH.   Carboy is then picked up by 
our biohazard safety laboratory on campus.  Dry waste, towels, wipes, etc 
are collected for incineration i.e paraffin trimmings also.  If we worked 
with sheep or CWD, then we would put sticky floor mats in front of doorway, 
and under microtome area.  Trimmings should stay in the room.

Sounds like a very uptight attitude for handling prions, but better to take 
stricter, proper precautions now and then have to change later.

Some people collect alcohols into bleach but when we did this, we noticed a 
huge heat reaction - that does NOT happen with NaOH so we opted for the 
latter just not not have the heat problem.

Gayle Callis
Research Histopathology Supervisor
Veterinary Molecular Biology
Montana State University - Bozeman
PO Box 173610
Bozeman MT 59717-3610
406 994-6367
406 994-4303 (FAX)

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