[Histonet] tracer & diluent dilemma [FLUORO-RUBY]

[John Kiernan]

Dear Dianna and other neuro-histonetters concerned
about "fluoro-ruby",

Try:
www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&
db=PubMed&list_uids=7678380&dopt=Abstract

This was the 2nd hit with a Google search for "fluoro-ruby",
and it identifies the substance as  fluorescently labelled
dextran amine. These compounds have been used as axon
tracers
for 10+ years, and there is a large body of literature. Much
of it is accessible (full text) on the web if you are at a
university or other institute with a library. 

I think "fluoro-ruby" is one of the tracers developed by
Dr Larry C Schmued and published in respected journals 
without declaration of the compound's chemical identity.
It's disconcerting that such secrecy can get past the
peer-review procedure. "Fluoro-gold"  
(a 2-hydroxy-4,4'-diaminostilbene salt) is another one, and
so is "Fluoro-jade" (the trisodium salt of mixed isomers
of carboxyfluorescein, a dye similar to fluorescein and 
eosin that binds to the basic proteins in the cytoplasm of 
dead cells). 
[Thanks to Adam Halberstadt (Univ of Pittsburgh) for telling 
me about US Patent 6,229,024, which is more informative than 
the original "fluoro-jade" publications. Adam's information
came as a Histonet reply in 2003. I'm quoting it now so 
that the reference to the patent will remain in the 
Histosearch archives for another year or two.]

The name "fluoro-gold" (for hydroxystilbamidine) quickly
entered the vocabulary of neuroscientists following its
introduction in 1986 (Schmued & Fallon. Brain Res.
377:147-154).
It's an excellent retrograde tracer and it has been used
in hundreds of published investigations. A Google search 
for hydroxystilbamidine brings up about 450 items, with 
the first few dozen applying to fluoro-gold as a retrograde
tracer. The compound has many other uses. Some of these
are noted (with refs) by Richard Horobin in Chapter 22 of
the 10th edition of Conn's Biological Stains. Fluoro-gold 
was adopted as the standard informal name of this 
fluorochrome because that was the name most often found 
in catalogues and publications. 

For more information about "fluoro-ruby" you could ask 
Larry Schmued.

lschmued <@t> nctr.fda.gov

His current (federal government) email address suggests 
that trade secrecy may be in the past. Expect a helpful
reply to your question. Fluoro-ruby is probably freely
soluble in water and isotonic buffered saline. This is
a guess, so don't just go ahead. Ask Schmued.

        John Kiernan
        London, Canada.
____________________________________
Dianne Holmes wrote:
> 
> What diluent and at what pH should be used to prepare Floro-Ruby?  Has
> anyone had problems with it not going into solution?
> 
> _______________________________________________
> Histonet mailing list
> Histonet <@t> lists.utsouthwestern.edu
> http://lists.utsouthwestern.edu/mailman/listinfo/histonet