Re: Testing for Beryllium
|From:||"J. A. Kiernan" <firstname.lastname@example.org>|
This reply does not answer your question about who does the assays!
It may clear up a few misconceptions, and it's also something of an
advert for inorganic histochemistry.
On Fri, 27 Oct 2000, Lott, Robert wrote:
> Does anyone know who does mass spectometry.... or spectrometric photo
> analysis... or any qual/quant testing for this metal in tissues? The
> differential in this case is sarcoid vs. chronic berylliosis? pt. has
> history of "multiple" exposures to heavy metals.
Beryllium (Be, atomic number = 4; atomic mass = 9) is not a "heavy"
metal. In fact, it's the second lightest!
In Pearse's Histochemistry it is pointed out that beryllium deposits
in tissue are dark (blue-black) in H&E sections and that they can be
fluorescent when unstained. Various dyes that bind to Be quench the
fluorescence. There are various histochemical tests involving formation
of coloured complexes of Be with dyes and other compounds. Most are
not specific, and give positive reactions with salts of other metals,
notably calcium, but also magnesium, aluminium and some heavy metals
including zirconium, thorium and some of the rare-earth elements.
These don't all cross-react with all the reagents, and they don't all
give complexes with the same colours, fluorescence or birefringence
as those seen with beryllium deposits. Pearse doesn't say it, but I
would suggest that it is necessary to carry out at least 3 different
histochemical tests to provide evidence that a lesion contains Be.
Some of the reagents used in beryllium histochemistry are dyes that
have multiple names, some of which have been applied to different
dyes. Pearse's is undoubtedly the most thorough histochemistry text
there is, but it has a weakness in the field of identifying dyes by
unambiguous names, C.I. numbers etc. Lillie's big book is better in
this respect, but his treatment of Be histochemistry (with 3 methods
recommended) is shorter and perhaps a little less scholarly than
that of Pearse. I would be surprised to learn that there is anyone
who makes a living doing beryllium histochemistry. No special
equipment is needed, but you do need the right reagents.
In association with a chemical assay, histochemistry could help
to make the link between a possible cause (high Be assay) and an
observed effect (localization of most of the tissue Be in rather
than between the lesions). It's a bit like one of Koch's postulates
for establishing that a bacterium is a pathogen.
John A. Kiernan,
Department of Anatomy & Cell Biology,
The University of Western Ontario,
LONDON, Canada N6A 5C1
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