Tony & everyone;
Do you have any reference/literature support for this( formaldehyde story)?
Could you forward? Has anyone looked at the this in a comprehensive fashion?
Does anyone have a running list of antibodies that are susceptible to
oxidation/degredation over time? I believe what would be more important would be
to generate a list of markers that are susceptible.   I have a few that I think
do degrade but have not really had the time to study it well.  Anyone have any
thoughts on this?

Tony Henwood wrote:

> Since Formalin fixation is a clockwork reaction ( It gets in, binds to
> proteins then cross links with other bound formalin molecules - simply
> speaking), it has been proposed that the crosslinking reaction can
> actually continue while the tissue is in the wax block. Some suggest that
> the high temperature of wax infiltration actually aids the reaction of
> formalin with nucleic acids, which require higher temperatures for the
> reaction with formalin to occur.
>
> >>> David Taylor Manager <DTMan@KINGMOWER.COM.AU>
> 10/April/2001 02:54pm >>>
> Dear Tony, I am curious to hear by what mechanism fixation continues in
> formalin fixed, paraffin embedded blocks of tissue. I thought a well
> processed piece of tissue embedded in paraffin wax was stable.
>  I understand that cut sections stored for an extended period don't stain
> as
> well as fresh cut sections when using certain Ab's due to (I think)
> oxidation and I have heard some Ab's simply won't work unless a
> section is
> cut fresh from the paraffin block. David.
>
> This might be due to antigens not reacting at all with the formalin,
> remember not every molecule in a cell will react with formalin. Possibly
> denaturing of epitopes in sections, though I have not found this to occur
> in my hands, probably don't use the same antibodies.
>
> David Taylor
> Laboratory Manager
> Drs King & Mower
> Adelaide, Australia
>
> -----Original Message-----
> From: Tony Henwood [mailto:AnthonyH@chw.edu.au]
> Sent: Monday, 9 April 2001 16:56
> To: CGerorge@Elliot-HS.org; KoellingR@immunex.com;
> histonet@pathology.swmed.edu
> Subject: RE: storing controls -Reply
>
> Cheryl,
> One thought is that since formalin fixation continues in the wax block (ie
> cross-linking), it might be possible that these archived blocks may need
> prolonged antigen retrieval, longer than sections cut from recently
> processed blocks.
>
> Any thoughts???
>
> Tony Henwood JP, BappSc, GradDipSysAnalys, CT(ASC)
> Laboratory Manager
> The Children's Hospital at  Westmead,
> Locked Bag 4001, Westmead, 2145, AUSTRALIA.
> Tel: (02) 9845 3306
> Fax: (02) 9845 3318
>
> >>> "George, Cheryl" <CGerorge@Elliot-HS.org> 6/April/2001 11:14pm
> >>>
> Hi Ray,
>     Currently we don't keep the patient blocks in the refridgerator but I
> have been giving it some serious thought lately; for a subgroup of cases
> (not enough space given our volume!).  Although I have never done a
> formal
> study for the loss of antigenicity by antibody, I have noticed a significant
> loss in breast stained for ER and PR when trying to find new controls
> using
> old patient cases. I will pull old known positive slides that are 4+ at
> initial staining and when the ER and PR are tested again, they tend to
> decrease to 2+ and in some cases even more.  These are the only two
> that I
> have noticed a problem with and so I am looking into the feasibility of
> storing those blocks in the fridge.
>
>     Has anyone else noticed this type of decrease with those antibodies?
>
> Cheryl
>
> > ----------
> > From:         KoellingR@immunex.com[SMTP:KoellingR@immunex.com]
> > Sent:         Thursday, April 05, 2001 3:22 PM
> > To:   George, Cheryl
> > Cc:   histonet@pathology.swmed.edu; 'Michelle Peiffer'
> > Subject:      RE: storing controls
> >
> > Cheryl,
> > Do you keep test (or patient blocks) in refrigerator?  Just curious about
> > your thoughts regarding having a control  block/section nicely positive
> > for
> > "X" from the refrigerator stained next to a test section/block for "X"
> > that
> > has been stored at room temp and is negative.  Would it truly be so?
> >
> > Thanks,
> > Ray
> > Seattle, WA
> >
> >
> >
> >
> >                     "George,
> >
> >                     Cheryl"               To:
> > histonet@pathology.swmed.edu, 'Michelle
> >                     <CGerorge@Elli        Peiffer' <mlk101@psu.edu>
> >
> >                     ot-HS.org>            cc:
> >
> >                                           Subject:     RE: storing
> > controls
> >                     04/05/01 09:36
> >
> >                     AM
> >
> >
> >
> >
> >
> >
> >
> >
> > Michelle,
> >
> > We store all of our control blocks and slides in the refridgerator.
> >
> > Cheryl
> >
> > > ----------
> > > From:         Michelle Peiffer[SMTP:mlk101@psu.edu]
> > > Sent:         Thursday, April 05, 2001 10:28 AM
> > > To:           histonet@pathology.swmed.edu
> > > Subject:           storing controls
> > >
> > > Thanks to all who responded about my IHC decreased staining post.
> > >
> > > Several people have mentioned storage of the controls.  Some are
> > purchased
> > > slides, so obviously they are precut and they are stored in the
> > > refrigerator.  But most are freshly cut from blocks which are stored
> at
> > > room temperature.  I was under the impression most people store
> blocks
> > at
> > > room temperature, is this correct?  How long can controls last?  We
> just
> > > started doing histology so our oldest blocks are only 6 months old.
> > >
> > >
> > > Michelle
> > >
> > >
> > > Michelle Peiffer
> > > *************************************************************
> > > Electron Microscope Facility for the Life Sciences
> > > Penn State University Biotechnology Institute
> > > 001 South Frear Lab
> > > University Park PA 16802
> > >
> > > phone: 814-865-0212
> > > email:  mlk101@psu.edu
> > > **************************************************************
>
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--
Luis Chiriboga Ph.D, H.T. (ASCP) QIHC
New York University School of Medicine
Department Of Pathology 4W27, Bellevue Hospital
27st & First Avenue
New York, NY 10016