From:"Timothy R. Wheelock"

 Hi All: 3 issues


Thank you for your continuing advice on microtomes, particularly 
regarding the issue of blade holder problems.
Dawn, I have not tried the Surgipath machine yet. I would be interested 
in hearing of your experience with it.
David, thank you for the info on Microm's  updated blade holder; I will 
ask the sales rep about trying it out.
Andi, thank you for the extensive, thoughtful response, from the sales 
rep's perspective, on demo equipment wear and tear, and asking  the 
companies for what you need.
Troy, thanks for pointing out  blade holders as the weakest link on 
microtomes. It points to a universal problem, not necessarily attached 
to any one brand of machine.

John, I actually use a cold and heated water bath with brain tissue. The 
cold bath is used to examine and  pick out  the best sections for your 
slide. The heated bath is for spreading the tissue out flat, getting rid 
of wrinkles. I lift the chosen section onto the the albumin-coated 
slide, transfer the section onto the heated surface, then pick it up 
again a second or 2 later onto the same slide.

With brain tissue, especially cortex,  trying to accomplish both tasks 
at once on the heated bath can be difficult, because in the time it 
takes you to choose  the section and extricate it from the ribbon, the 
section you want can expand too much  to the point where it  will no 
longer fit on the slide, or  two adjacent cortical areas will  drift 
away from one another more than they have to, or  the tissue can 
actually fly/break apart on the bath. By doing the choosing  and ribbon 
slicing on the cold bath, you  minimize the time needed  on the heated 
water surface.

Also, a student of mine came up with  another trick. If you have a piece 
of tissue that has a tendency to fly apart on the heated water (it could 
be a processing problem),  pick the tissue up on a slide from the cold 
bath, then lie the slide on the surface of the heated water (the tissue 
never comes in contact with the water). The thin layer of  water between 
slide and tissue will slowly  heat up and slowly flatten the tissue. 
This technique gives one great control of the flattening process. It's 
great if you have, say, 8 pieces of spinal cord in a block. This sort of 
section can be a nightmare, with pieces of cord flying off in different 
directions. But with the heated slide technique, it becomes manageable.


Curt, we see CJ  less than once a year. We take in about 300 cases total 
per year. This Brain Bank opened its doors in 1978. The first few years 
were slow, so I would guess we have seen around 15 cases. When our 
neuropathologist  makes the diagnosis, we send the report, and all the 
fixed and frozen tissue to a researcher at the NIH who specializes in 
studying CJ.

Tim Wheelock
Brain Bank
McLean Hospital
Belmont, MA

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