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Many pointed out that one can interpolate from the begin and end of
acquisition times which are recorded on the 310. A problem with this
pointed out by some is that unless the sample is continuously stirred
during acquisition, sedimentation of cells will change the event rate.
Hence, event number is not linearly related to time. When time is recorded
on newer cytometers, a histogram of time often shows fewer events at late
times due to sedimentation.
We've done some Ab-binding kinetics studies on the 310 in which we recorded
the live-display of event rate vs. stopwatch readings during acquisition.
We then fitted time vs. events to a 4th degree polynomial, allowing us to
calculate the actual time for each slice of the file. The resulting data
gave a good fit to the 1-site Michaelis-Menten binding equation, so it
can be done.
A version of MFI soon (?) to be released (release will be announced here)
will plot any parameter vs. event number (for cytometers which can't record
time), either as a dot plot or a line plot. It will also do line plots
vs. time when it is recorded as a parameter, as well as dot plots. The
presently available version, of course, will already do time-slicing,
giving slice medians and means. (Get MFI by anonymous ftp from
flowcyt.bio.umass.edu in /pub/flowcyt/mfi. Be sure to get the tutorial
with sample data files MFITUTOR.EXE as well as MFI.EXE.)
/*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Eric Martz, Professor of Immunology emartz@microbio.umass.edu
Dept Microbiology Voice: 413-545-2325 FAX: 413-545-1578
Morrill IVN 203, Box 35720, Univ Massachusetts, Amherst MA 01003-5720
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