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Regarding your recent question to the Cytometry Mailing list:
>>>
We have been trying to determine percentage of apoptotic cells using PI
staining and analysis of DNA histograms with Modfit LT. The program works
very nicely, but occasionally we get a histogram in which a substantial number
of cells appearing in the G0/G1 and the S peaks are considered by Modfit as
apoptotic cells. Verity does not provide any "explanation" or suggestions
regarding how to get around that. Did anyone out there encounter this same
problem and how was it resolved? Thanx for any info.
<<<
I apologize for not jumping in and responding to your question sooner. I've been
on vacation.
Let me take a shot at what's happening to you. I'm going to assume that you are
using Auto Analysis. When the Apoptosis option is turned on (menu item
checked), Auto Analysis assumes the apoptotic population to be the first peak it
finds in the sample. Tthe peaks the program finds are indicated by arrows under
each one. On occasion, ModFit LT can miss an apoptotic peak because its CV is
too large or its area to small to pass the test for "is this a real peak". In
this case, LT will place the apoptotic range over the wrong peak, probably the
DNA Diploid G0-G1. To correct the problem, you need to select the "Range"
button and manually position the "APOP" range over the apoptotic population, and
each of the other ranges over their respective populations. After adjusting the
ranges, choose the "Fit" button to re-analyze the sample.
I was unable to tell from your message whether you tried to get help from us and
we failed to assist. If this is this the case, please let me know so that I can
determine how we can improve our support services. You can call me at 207 729
6767 and I or anyone else here would be happy to assist you in solving your
problem.
I hope this solves your problem. Please let me know if I can be of any further
assistance.
Sincerely,
Ben Hunsberger
General Manager
Verity Software House
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