New DNA research study results from University of Pittsburgh described.

"DNA repair, a fundamental function of cellular metabolism, has long been presumed to be constitutive and equivalent in all cells. However, we have previously shown that normal levels of nucleotide excision repair (NER) can vary by 20-fold in a tissue-specific pattern," scientists in the United States report (see also DNA Research).

"We have now successfully established primary cultures of normal ovarian tissue from seven women by using a novel culture system originally developed for breast epithelial cells. Epithelial cells in these cultures aggregated to form three-dimensional structures called ''attached ovarian epispheres''. The availability of these actively proliferating cell cultures allowed us to measure NER functionally and quantitatively by the unscheduled DNA synthesis (UDS) assay, a clinical test used to diagnose constitutive deficiencies in NER capacity. We determined that ovarian epithelial cells manifested an intermediate level of NER capacity in humans, viz., only 25% of that of foreskin fibroblasts, but still 2.5-fold higher than that of peripheral blood lymphocytes. This level of DNA repair capacity was indistinguishable from that of normal breast epithelial cells, suggesting that it might be characteristic of the epithelial cell type. Similar levels of NER activity were observed in cultures established from a disease-free known carrier of a BRCA1 truncation ...