facs loader

From: Marcia Woda (Marcia.Woda@banyan.ummed.edu)
Date: Thu Jan 29 1998 - 08:52:31 EST


We bought a loader last summer for a calibur for the precisely the reasons 
C.Prussin laments about in a recent post. It has been well worth the 
investment and functions very well for both research and clinical 
applications. We had some initial problems with the tubes not going up or 
down correctly but a lube job on the lifting mechanism of the metal shaft 
that pushes the tubes up fixed that. We also had some concerns about 
contamination between samples and poor sample measurements recorded during 
that time of high flow rate the calibur gives when the sample first goes on 
as there is no option in the s/w to delay acquisition between samples. We 
have not seen any problems in 8 months worth of data that includes a lot of 
triplicate testing and racks of PI stained cells that gave histograms with 
very tight CV's. The only problem I do see is  when one's precious sample is 
resuspended in minimal volume(DCM sleeve on) some of the sample is sucked 
away while the program is frantically looking for a place to store a one 
million event file. I know the electronics exist to build a system that can 
keep track of the total cell count for determining the frequency of a rare 
population while storing a more modest list-mode file of n parameters of the 
cells of interest only. 
 
I can't be sure this is the reason, but it seems harder to maintain the 
timing of the second laser now with the loader present-possibly due to the 
tube being pushed up tight against the cushion/gasket for a good seal moving 
the whole flow cell assembly above it.  Know where the timing screw is.

Loader s/w performance on a Quadra was not very good-greatly improved on a 
power mac. A high speed reliable printer is essential because any printing 
problems can abort the rack-run. HP color printers with the plastic rollers 
are terrible. 

It is hard to get excited by flow after a long time of doing it but I 
remember breaking into a  big smile and being marveled the first time I 
watched the loader-manager s/w control the sample carousel while running 
their Multitest s/w that performs expert gating of lymphocytes and subset 
evaluation in 4 color stained blood samples.  

 We are very satisfied with the loader's performance in a broad range of 
applications, especially the one mentioned, and have had little trouble with 
it. Is is hard getting people to use the Scan which doesn't have one...



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