Citrate-theophylline-adenine-dipyridamol buffer is preferable to citrate buffer as an anticoagulant for flow cytometric measurement of platelet activation.

for the 3238G3A variant, which was amplified from fresh breast tumor tissue. As far as we know, we report here for the first time the use of DGGE to detect selective retention of deleterious BRCA1 alleles in tumor DNA extracted from either paraffin-embedded or fresh tissues. DNA extracted from paraffin-embedded tissue can be a poor PCR template because it very often is severely damaged, and DGGE primers add difficulties to the PCR reaction because of the long 40to 50-bp GC-clamps used to improve melting profiles (18 ). Nonetheless, the method reported here has been applied successfully to the analysis of different BRCA1 exons amplified from several distinct paraffinembedded tissues. The present method takes advantage of the fact that BRCA1 is a highly polymorphic gene and that nearly all screened individuals are heterozygous for one of the well-known more common polymorphic sequences (19 ). The method can be an advantageous alternative to microsatellite studies when analyzing BRCA1 LOH, especially for laboratories that use a DGGE method for screening BRCA1 mutations. However, a comparative study with the standard microsatellite-based LOH assays should be performed. Analysis of selective allele tumor retention performed in common polymorphic BRCA1 sequences and mutant exons can be a powerful method of defining BRCA1 mutation-associated haplotypes. This method can also be applied to the identification of sporadic breast/ovarian tumor development in women already identified as harboring a germ-line BRCA1 mutation. We also believe that this approach can be applied to the detection of tumorselective retention of deleterious mutant alleles of tumor suppressor genes other than BRCA1.