Androlog Mail:
Tammie K. Schalue:
"...suggestions for performing QC on the hypoosmotic swelling (HOS) test"
While we do not perform the HOS test we do have a lot of experience
in establishing a QC/QA and positive / negative controls for the
Optimized SPA. Since both tests are bioassays you might try the
approach we use; freezing aliquots of single semen specimens
(not pooled) from known high and low scoring individuals. We all
recognize that any bonafide system used to monitor assay quality must
subject the same test material to identical and parallel processing.
The only way of achieving this, in this case, is to preserve semen
aliquots in liquid nitrogen. I appreciate that you values will be greatly
diminished after a freeze/thaw. However, your ultimate goal is to
demonstrate acceptable inter-assay reproducibility on a negative
and a positive specimen. The only problem is those values will
obviously be in a lower range as their corresponding fresh HOS values.
One big benefit of this method is that by micro-sizing the aliquots you
could easily harvest 200 control aliquots from a single specimen.
This means you could use the Westgard Rules to monitor
assay compliance (these rules are valid after establishing a pattern of
the first 20 independent control run values). Another consideration is to
perform a swim-up (not density gradient) on a high HOS sample and
customize your freeze protocol to *pre-load* your positive control such
that the resulting freeze/thaw scores are consistent with the positive
*fresh* scores. Warning: be very consistent with the thaw procedure
and the exact timing of the test run since frozen/thaw sperm are much more
sensitive to alterations in processing and incubation times than fresh
sperm. QC for any bioassay using live motile cells is very difficult but
it can be done. It has helped us confidently compare SPA results on
patients that were tested years apart. Good luck!
Johnson A.R., Bassham B., Lipshultz L.I. and Lamb D.J.: A Quality
Control System for the Optimized Sperm Penetration Assay. Fertility &
Sterility, Vol. 64 No. 4, pg. 832, 1995.
Westgard J.O., et. al.,: A Multi-Rule Shewhart Chart for Quality
Control in Clinical Chemistry. Clinical Chemistry, 27, pg. 493, 1981.
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Aron Johnson, T.S. Research Facilitator
Andrology/Embryology Laboratory
Oregon Health Sciences University, Portland, OR
www.ihr.com/oregon
(503) 418-3136
johnsoar@ohsu.edu
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