Help!

From: sandeep ramalingam (sandeeprk@yahoo.com)
Date: Thu Jan 24 2002 - 14:44:17 EST


Hello,

I am writing this mail requesting some urgent advice.
Please forgive me if this message is long.

I work with a Facscan (with a HP computer).  Today I
was to analyze some samples (estimation of CD4 /CD8/
CCR5/CXCR4 positive cells with the Simulset software).
 When I ran the calibrite beads (with Autocomp), the
PMT voltages could not be set automatically.  The
event rate was very high at around 1500.  I then
realized that even when the machine was in "standby"
mode, there events were visible on the screen (event
rate of around 600).  I was able to stop these events
by increasing the threshold of Forward scatter from 52
to 100 with the machine on standby.

I subsequently ran the samples by manually setting the
PMT voltages, the compensation and increasing the
threshold.  I have two questions.

1.  Am I allowed to manually set these values and
interpret the results (The Differential count of the
samples by the FACScan matches with the differential
by a Coulter GenS system)

2.  What could be the problem?  I have to state that I
did open the panels on the sides of the machine and
the top cover in order to fix a leak in the fluidics
(at the coupling where the tube from the sheath tank
is attached - it takes some time for the engineers to
come to this part of India).  However, I did not touch
the flow cell / laser /lenses/ detectors.

I need this information as the engineers from BD are
unavailable (one person in abroad and the other person
is incommunicado) for the next few days.  Also some
patients have appointments for Tuesday.

I would appreciate a response ASAP.  I will be out of
town from Saturday until Monday and hence tomorrow
(Friday) is the only day I have to fix the problem, if
minor, before I leave.

With regards,

Sandeep.

=====
Dr. Sandeep Ramalingam,
Department of Clinical Virology,
Christian Medical College Hospital,
Vellore-632004, India.
Phone(off): 91-416-222102, ext 2070
Fax: 91-416-232035
Email: sandeeprk@yahoo.com

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