Re: [Histonet] PhosphoGuard fixative additive

Although I have not used this and do not know anything about this product, in a former life I did something like it.  When starting to work with phospho targets years ago in IHC was worried about the transient nature of phosphorylation/dephosphorylation. Do Westerns to ID target and you are under the constraint of time and adding phosphate inhibitors to your lysate so your target doesn't degrade.  So how did this relate to a tissue block where fixation is not immediate throughout.  I started adding reversible inhibitors or non-reversible inhibitors to fixatives and did in a sense find what we sought.  In some cases, couldn't improve results.  But for sure, some specific phosphorylated targets we absolutely saw better and stronger signal and in some cases went from no/poor signal to very good signal.  So I think the theory for why the product should work is sound and we did this a lot in a proprietary sense, but again do not know about this specific product.

Ray Koelling
PhenoPath Labs
Seattle, WA

 -------------- Original message ----------------------
From: "Connolly, Brett M" 
> In the June 2008 issue of CAP Today, I ran across a fixative additive
> called PhosphoGuard from Targeted Molecular Technologies. 
> They claim it prevents degradation of phosphorylated and activated
> proteins allowing for better IHC detection (stronger/more abundant
> signal) by better inactivation of phosphatases compared to plain 10%
> NBF.  Apparently you just add some to your formalin. 
> You can check it out further on their website.
> Just wondering if any of you have tried it?
> Brett
> Brett M. Connolly, Ph.D.
> Research Fellow, Imaging Research
> Merck & Co., Inc.
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