UC Davis Geology department also has at least some of these capabilities if
the community college doesn't work out. They have the capability to do
electron microprobe analysis of tissue sections mounted on carbon
planchettes for SEM. I did a project on silicosis in horses using their
facilities, so if this is the route you want to take, contact me directly
and I can answer any questions you have. The contact at the geology
department is Sarah Roeske:  roeske@geology.ucdavis.edu

Cindy Farman
Sierra Biomedical, Inc.
Sparks, NV
cfarman@sierrabiomedical.com


-----Original Message-----
From:	Philip Oshel [SMTP:oshel@terracom.net]
Sent:	Friday, October 09, 1998 10:53 AM
To:	histoNet@Pathology.swmed.edu
Subject:	Re: Mercury poisoning tissue stain?

Mark,

Do you have access to an SEM with an energy-dispersive x-ray spectrometer
(EDX) on it? Or for greater sensitivity, an SEM or microprobe with a
wave-length dispersive spectrometer (WDX)? Many companies (especially
electronics) have these, as well as colleges. (You anywhere near the San
Joaquin Valley delta? S.J. Delta community college has one of the best EM
programs in the country, and they have this equipment.)

If so, try fixing tissue believed to be contaminated as for TEM, but then
instead of embedding, dry (critical-point or HMDS), poke apart the specimen
with a bit of plastic or glass, then mount for SEM.

These techniques might not be sensitive enough on whole tissue, but then
again, they easily can be. EDX is good to about 1 atomic weight %, and WDX
to about 0.5 to 0.1 atwt%, depending on the sample. Mercury being a heavy
element will give good strong
K and L lines in the spectra.

EDX can also be done on specimens prepared and thin-sectioned for TEM,
using an analytical STEM. These are common in materials science departments
and in some central EM facilities.

EDX's main advantage is that it can map the distribution of the elements
(Hg, here), and demonstrate in what cells, or where in the cells, the Hg is
concentrated.

If the mercury can't be detected in the intact tissue, Ms. Wenk's
micro-incineration idea would work: ash the specimen in a muffle furnace at
500 deg. C, then analyze the ash in an SEM with EDX or WDX.

Phil

>Hi all -
>I appreciate the information passed around on this list server.  As stated
>early, I also find myself laughing outloud at "life in the lab".
>
>On a serious note, we are doing a postmortem on a baby who died of mercury
>poisoning.  The mother died days earlier.  Can you believe this, she was
>boiling off mercury to concentrate gold from her prospecting?  I know
>there's gold to be had for a price in the mountains, here in California
...
>but at what price??!!
>
>Has anyone been able to demonstrate tissue deposition in acute, possibly
>chronic mercury poisoning cases? Does anyone have a good tissue stain for
>mercury deposits, our pathologist would like to demonstrate deposition if
it
>can be stained? Kidney? Liver? Brain?  Are there any tissues in anyone's
>"banks" that has demonstrated positive mercury staining so I could
validate
>any finding on this unfortunate case?  Thanks.
>
>Mark Briones
>Valley Children's Hospital
>Madera CA USA
>vchanatomicpath@hotmail.com

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Philip Oshel
Technical Editor, Microscopy Today
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Middleton, WI  53562
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