{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T21:08:27Z","timestamp":1777928907987,"version":"3.51.4"},"reference-count":0,"publisher":"S. Karger AG","license":[{"start":{"date-parts":[[2009,6,17]],"date-time":"2009-06-17T00:00:00Z","timestamp":1245196800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"},{"start":{"date-parts":[[2009,6,17]],"date-time":"2009-06-17T00:00:00Z","timestamp":1245196800000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/karger.com\/pages\/terms-and-conditions"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Oncology"],"abstract":"<jats:p>The expression of a mouse mammary tumor virus is inducible by hormones, and the virus contains a hormone-responsive element. Viral particles and RNA-directed DNA Polymerase (RDDP, EC 2.7.7.7; reverse transcriptase) are both detectable in human breast tumors but the frequency and significance of these findings are unknown. Breast tumor biopsy specimens (from either the primary site or a metastasis), frozen in liquid nitrogen at the time of surgery, were routinely obtained to determine estrogen receptor (ERP) concentration. A sample of the tissue was pulverized, homogenized and centrifuged at low speed to remove nuclei and mitochondria. The supernate was then centrifuged at 225,000 g to obtain the cytosol fraction for estrogen and progestin receptor (PgR) assays. Partially purified membranes for the RDDP assays were prepared from the high-speed pellet by discontinuous sucrose density gradient centrifugation. The RDDP assay involved measuring primer-dependent poly(dT) synthesis in the presence of poly(A) as template and oligo-(dT)&lt;sub&gt;12\u201318&lt;\/sub&gt; as primer. To date, we have studied biopsy specimens from 46 patients with breast cancer. 27 (59%) had ERP and 23 (50%) were RDDP-positive. There was no significant correlation between ERP concentration and RDDP activity. PgR data were available on 36 of the patients; 17 (47%) were positive. No correlation between RDDP and PgR was apparent. Similarly, there was no correlation between RDDP and clinical stage of the disease.<\/jats:p>","DOI":"10.1159\/000225834","type":"journal-article","created":{"date-parts":[[2009,6,18]],"date-time":"2009-06-18T03:35:18Z","timestamp":1245296118000},"page":"257-263","source":"Crossref","is-referenced-by-count":0,"title":["RNA-Directed DNA Polymerase Activity in Human Breast Cancer Biopsy Specimens"],"prefix":"10.1159","author":[{"given":"Gary B.","family":"Weiss","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Boyd K.","family":"Carr","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Barbara","family":"Rae-Venter-Huff","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"127","published-online":{"date-parts":[[2009,6,17]]},"container-title":["Oncology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.karger.com\/Article\/Pdf\/225834","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/karger.com\/article-pdf\/doi\/10.1159\/000225834","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T23:24:07Z","timestamp":1777677847000},"score":1,"resource":{"primary":{"URL":"https:\/\/karger.com\/article\/doi\/10.1159\/000225834"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2009,6,17]]},"references-count":0,"URL":"https:\/\/doi.org\/10.1159\/000225834","archive":["Portico"],"relation":{},"ISSN":["0030-2414","1423-0232"],"issn-type":[{"value":"0030-2414","type":"print"},{"value":"1423-0232","type":"electronic"}],"subject":[],"published":{"date-parts":[[2009,6,17]]}}}