[Overton Subtraction] - here is the weblink

J. Paul Robinson jpr at flowcyt.cyto.purdue.edu
Thu Jun 21 21:44:28 EDT 2007


You should all know that Wiley Have made all back issues of Cytometry 
freely available on the internet - this includes way back to the first 
volume. I generally gain access at this address but this may be related 
to my institutional link...of course, all ISAC members have access to 
either the hard copy or electronic versions of Cytometry Part A:

I think that you should be able to get the paper here


With Kind regards
Paul Robinson

W. Roy Overton wrote:
> Christine,
> The 1% positive gating method works well when the positive cells are
> brightly stained, giving a good separation between the positives and
> negatives.  In those samples, the 1% method and Overton Subtraction will
> give the same results.	However, if the sample has dim positives, the 1%
> method becomes less reliable and less meaningful, because there may be
> positive cells that are dimmer than the 1% cutoff.  The Overton Subtraction
> method finds the maximum difference between the test and control samples and
> defines that difference as the percentage positive.  Standard histogram
> subtraction does the same thing, except that it can give false positives due
> to random channel to channel variations in the data, which are eliminated by
> Overton Subtraction.	Note that if the sample has both dim and bright
> positive cells and you only want to know the percentage of bright cells, all
> of these methods may give you the wrong answer.  In those cases, cytometry
> becomes an art and you must select the appropriate analysis region manually.
> A more detailed explanation can be found in the original publication of the
> method:
>    Modified histogram subtraction technique for analysis of flow cytometry
> data
>    Cytometry, Volume 9, Issue 6, Date: November 1988, Pages: 619-626
> If you don't have access to that ancient issue of Cytometry, I think I still
> have a few dusty reprints left.
> Best regards,
> Roy
> ****************************************************************
> W. Roy Overton, Ph.D.
> GCAT, Inc.
> Tel: 856-478-0019		
> Fax: 856-478-9531
> overton at gcatinc.com
> http://www.gcatinc.com/
> **************************************************************** 
> -----Original Message-----
> From: Christine Dahl [mailto:CHRISTINE.DAHL at KI.AU.DK] 
> Sent: Tuesday, June 19, 2007 5:27 AM
> To: cyto-inbox
> Subject: [Overton Subtraction]
> Dear All!
> I need help in explaning and understanding the difference between 1%
> positive gating and Overton subtraction of histograms.
> Thank you in advance and for alle the good answers we can find here!
> Sincerley
> Christine Dahl
> Skejby University Hospital
> Dep. of Pediatrics
> Denmark

J. Paul Robinson
SVM Professor of Cytomics
Professor of Immunopharmacology & Biomedical Engineering
Director, Purdue University Cytometry Laboratories
President, International Society for Analytical Cytology

Purdue University Cytometry Laboratories
Bindley Bioscience Center
1203 West State Street
Discovery Park, Purdue University
West Lafayette, IN 47907-2057
Ph (765) 494 0757; Fax (765) 494 0517
email: jpr at flowcyt.cyto.purdue.edu

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