[Histonet] Microwave Processing

Wed Apr 21 10:51:33 CDT 2004

Geez, tetchy begger aren't you. I'll answer when I've thunk about it and
give you an answer that is both lucid and structured.

<grumbles> this used to be fun; why are some people so......

Mr Kemlo Rogerson MSc DMS MIBiol CBiol FIBMS
Tel: 0208 970 8414
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Mobile E-Mail kemlorogerson <@t> 3mail.com                     
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-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Marshall
Terry Dr,Consultant Histopathologist
Sent: 21 April 2004 15:51
To: Kemlo Rogerson; Steven E. Slap; kevin williams;
histonet <@t> pathology.swmed.edu
Subject: RE: [Histonet] Microwave Processing

Kemlo asks:

"Am I talking a load of..........."

Inevitably:-)

Kemlo,

You talk as if formalin was the only fixative. What about the group
called, oddly enough, coagulative fixatives? 
Now .... I wonder how they work. Let me see ......
Furthermore, you flit between the several different subjects in an
unstructured way.

When you say :
"Its job is also that of preventing putrefaction both by endogenous and
exogenous means
(lysosomes and bugs)."

You are wrong on 2 counts.
Its effect may be to prevent putrefaction, but hardly its job. (I
realise that some books list this, but a dehydrated specimen in wax is
more at risk from mice than bacteria).
Furthermore, the action you refer to, attributed to lysosomes, is
autolysis, not putrefaction.

Furtherfurthermore, a fixed egg will only elude putrefaction by virtue
of the retained/residual fixative fixing any bacteria with ungodly
thoughts toward the egg, wouldn't it?
That is to say, "resistance to putrefaction" will be a property that
resides in the fixative not in the fixed egg.

Yours lovingly, 

Confused from Rotherham

Dr Terry L Marshall, B.A.(Law), M.B.,Ch.B.,F.R.C.Path
 Consultant Pathologist
 Rotherham General Hospital
 South Yorkshire
 England
        terry.marshall <@t> rothgen.nhs.uk

-----Original Message-----
From: Kemlo Rogerson [mailto:kemlo <@t> tiscali.co.uk]
Sent: 21 April 2004 15:16
To: Marshall Terry Dr, Consultant Histopathologist; 'Steven E. Slap';
'kevin williams'; histonet <@t> pathology.swmed.edu
Subject: RE: [Histonet] Microwave Processing

Um....... A boiled egg is stabilized but not fixed; does that help? A
fixative is designed not only to stabilize proteins by coagulation, but
in most cases it links chemically to the proteins. Its job is also that
of preventing putrefaction both by endogenous and exogenous means
(lysosomes and bugs). A boiled egg will rot by putrefaction, but if you
fixed it, then it wouldn't; would it? Heat stabilizes by coagulating
protein doesn't it, formalin forms links between reactive sites on the
proteins, doesn't it? 

Mr Kemlo Rogerson MSc DMS MIBiol CBiol FIBMS
Tel: 0208 970 8414
Mob: 07830 196072 
Mobile E-Mail kemlorogerson <@t> 3mail.com                     
FAX & Answer Phone 0871 242 8094
E-mail Accounts:  
             kemlo <@t> tiscali.co.uk or 
             kemlo1 <@t> btinternet.com 
Disclaimer: The information contained in this message and/or any
attachments(s) may be of a private and confidential nature, and is
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deleted from your system. Unauthorised usage, copying, disclosure or
alteration of this message and/or attachment(s) is strictly prohibited.
Barking, Havering and Redbridge Hospitals NHS Trust will not be held
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resulting from the transmission of a virus.

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Marshall
Terry Dr,Consultant Histopathologist
Sent: 21 April 2004 12:48
To: Steven E. Slap; kevin williams; histonet <@t> pathology.swmed.edu
Subject: RE: [Histonet] Microwave Processing

My confusion has not been dispelled.

Steven writes:

"The saline will not work 
alone as a fixation step, except in the case of 
very small biopsies (as written up in an article 
by Tony Leong)- ..." 

In the next post, we get:

"Yes, in the Leong method for biopsies, the specimens are heat 
stabilized in the microwave in saline, and not really chemically 
fixed.  They get fixed in the ethanol in a traditional processor ..."

These statements are mutually incompatible.

Moreover, what is the difference between "stabilisation" and "fixation".

A further muddle is introduced by:

"not really chemically fixed."

Well, hell, are they fixed or no? Heat fixation is fixation - who cares
whether chemically fixed?

Of course, the major problem is that mechanisms of fixation are varied
(with the fixative) and not well understood.
(Speak for yourself do I hear someone say?)

Dr Terry L Marshall, B.A.(Law), M.B.,Ch.B.,F.R.C.Path
 Consultant Pathologist
 Rotherham General Hospital
 South Yorkshire
 England
        terry.marshall <@t> rothgen.nhs.uk

-----Original Message-----
From: Steven E. Slap [mailto:siksik03 <@t> comcast.net]
Sent: 17 April 2004 22:54
To: Marshall Terry Dr, Consultant Histopathologist; kevin williams;
histonet <@t> pathology.swmed.edu
Subject: RE: [Histonet] Microwave Processing

Hi Terry & HistoNetters

I have done lots of successful large organ 
stabilization in saline at 65°C for 20-35 minutes 
(depending on the size of the organ.  However, it 
is important to emphasize that the purpose of 
this step usually is to firm up the tissue so 
that it can be subsequently cut up into thinner 
pieces for processing, which must include a 
fixation step, either in the microwave or on a 
conventional processor, in formalin or some 
non-formalin fixative.  The saline will not work 
alone as a fixation step, except in the case of 
very small biopsies (as written up in an article 
by Tony Leong)-  a procedure I have not tried 
myself.

best regards,
Steven Slap
Microwave Consultant

At 3:58 PM +0100 4/16/04, Marshall Terry Dr,
	Consultant Histopathologist wrote:
>Sorry to but in - but on a related question - 
>does anyone do microwave fixation in saline as 
>described by for instance the Melbourne group, 
>which involves bringing up to 65C in saline?
>Have tried it this week and the sections are even crummier than usual.
>When I was in Tasmania, a local private lab. did 
>it and their sections were fine.

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