In my opinion/experience:
The upside of using a microwave for HIER is that you can remove some slides
at certain intervals, and keep heating the rest (replacing the removed
slides with blanks, so as to keep the same amount of material inside the
machine). My microwave HIER protocols vary in length from 5' up to 20' (in
5' increments, replacing buffer volume if needed), so being able to remove
at the right times is essential. I often have 5-6 different times and
buffers going, and could not spend the extra time trying to do HIER
separately on each one. The downside to using a microwave is the
verifiability of temperature, if you don't have a fancy laboratory
microwave. I'm currently looking into the various models and price ranges
out there for a new one that will record temps, etc.
Steam retrieval in a vegetable steamer is great. However, the downside to
steam retrieval is the amount of time needed to heat up the
slides/solutions. Sixty minutes is just too long for my turn-around time.
Most days, I think 20 minutes is too long!
Pressure cooker HIER works really well, too, but you run into a problem if
all your tests for that day don't use the same amount of time in HIER. Once
you break that seal to remove some of the slides that need a short heating
time, your temp/pressure are gone.
I work in an animal diagnostic lab, and our usual workload is about 150
slides/day, so we need to get the slides in and out fairly rapidly. Thus,
the reason why microwaving works best for me. Others will have different
needs and time allowances in their labs.
P.S. a) I always start with cold buffer prior to heat retrieval. b) I
always cooldown in HIER buffers for 20'.
----- Original Message -----
From: "Perry, Margaret"
Sent: Wednesday, October 22, 2008 11:28 AM
Subject: [Histonet] HIER
We have been using the microwave HIER and have had good results, however
when our microwave bits the dust I would like to have a pressure cooker
method in place. I feel the pressure cooker is more consistent for all the
slides. We are a veterinary diagnostic lab and I would like to have some
idea of where to begin. I have looked at different protocols and they often
indicate HIER in a pressure cooker but do not give the details. I currently
use citrate buffer pH 6. I put the slides in refrigerated buffer and
microwave on high for 1 min 45 sec. or until the buffer just starts to boil.
I then set the microwave on 10% power for 10 minutes. Afterward the slides
are allowed to cool in the microwave for 1 hour. We have a biocare
Decloaker Chamber and I would appreciate help with the program I should use.
Do you start with cold buffer or should I prewarm it? What temperature
should I use? How long should I maintain the temperature? How long should
it be before I remove the slides?
I also am working with a new protocol that calls for heating in a steamer.
Should the temperature of the buffer be warm, cold or room temp when I
Margaret Perry HT (ASCP)
IHC Lab Manager Veterinary Science
Animal Disease Research and Diagnostic Lab
South Dakota State University
Box 2175 North Campus Drive
Brookings SD 57007
Histonet mailing list
Histonet mailing list