[Histonet] PAS vs CAS

[Lee & Peggy Wenk]

I think what Bryan suggested would work. 

For our GMS, we usually use 10% chromic acid for 10 minutes at room temp,
and they look great. However, when I tried the 10%/10 min for the CAS, only
about half the fungi stained. When I reduced the time to 5 minutes, more
stained, and brighter pink. So I think the fungi were being over oxidized. 

So 5% at room temp for 10 minutes sounds like it should improve the
staining.

Let us know.

Peggy Wenk, HTL(ASCP)SLS
William Beaumont Hospital
Royal Oak, MI 48073

-----Original Message-----
From: histonet-bounces <@t> lists.utsouthwestern.edu
[mailto:histonet-bounces <@t> lists.utsouthwestern.edu] On Behalf Of Bryan
Llewellyn
Sent: Tuesday, October 18, 2005 4:14 PM
To: Histonet
Subject: Re: [Histonet] PAS vs CAS

In my haste I didn't note the 42C temperature.  Try it at room temperature.

Bryan Llewellyn


----- Original Message -----
From: "Bryan Llewellyn" <llewllew <@t> shaw.ca>
To: "Histonet" <histonet <@t> lists.utsouthwestern.edu>
Sent: Tuesday, October 18, 2005 1:05 PM
Subject: Re: [Histonet] PAS vs CAS


> Try oxidising in the 5% chromic acid for about an hour.  That was Bauer's 
> original recommendation (4% for 40-60 minutes).  Alternatively, many have 
> found a 10% solution for 10 minutes satisfactory.  You could also do a 
> double oxidation with periodic acid.  That is oxidise in 1% periodic acid 
> for 15 minutes, block aldehyde with aniline-acetic for 30 minutes, then 
> re-oxidise for 15 minutes.  This also reduces background positive PAS 
> staining.
>
> Bryan Llewellyn
>
> Bryan Llewellyn
> ----- Original Message ----- 
> From: "Cindy DuBois" <dpahisto <@t> yahoo.com>
> To: "Histonet" <histonet <@t> lists.utsouthwestern.edu>
> Sent: Tuesday, October 18, 2005 10:46 AM
> Subject: [Histonet] PAS vs CAS
>
>
>> My lab manager recently read the article by Vinnie Della Speranza et. al.

>> on fungus staining.  He wanted us to try the Chromic Acid Schiff's (CAS) 
>> procedure and compare it to our PAS procedure.
>>
>> Although I get some staining with the CAS, only about half of the fungus 
>> is staining and it is very light.
>>
>>  I used the following procedure:
>> 1.  Clear & Hydrate slides (standard protocol).
>> 2.  Incubate slides in 5% Chromic acid in water bath (temp approx. 42C) 
>> for 10minutes.
>>          Solution was pre-heated for 10 minutes.
>> 3.  Rinse and incubate in Schiff's solution for 10 minutes.
>> 4.  Rinse in hot water.
>> (Our tap water has a lot of sulfur in it and therefore we do not normally

>> do the sulfuric acid rinse).
>> 5.  Counterstain in Working Light Green, dehydrate and coverslip.
>>
>> If any one is using this procedure for their fungus stain would you 
>> please send me your procedure?
>>
>> Cindy DuBois, HT ASCP
>> Integrated Pathology Associates
>> Stockton CA
>>
>>
>>
>>
>>
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>
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