摘要：Proliferating cell nuclear antigen (PCNA), an endogenous nuclear protein, has recently been used to identify replicating cells. PCNA was compared to tritiated thymidine ([3H]-TdR), a reliable and accurate exogenous labeling agent, to ascertain if PCNA gives comparable results for quantitative cell proliferation. Male F344 rats were treated with a single dose of 500 mg/kg 4-acetylaminofluorene (4-AAF), a known liver mitogen. Rats (n = 5) were euthanized and necropsied at 6, 12, 18, 24, 36, 48, 96, or 192 hr after treatment. Two hours before necropsy, rats were pulsed-dosed with [3H]-TdR (2 mCi/kg body weight). Livers were sectioned, autoradiography performed, and labeling indexes (LI), a measurement of the percentage of S-phase hepatocytes, determined. One and a half years after the completion of this study, the archival paraffin blocks of the liver tissue were sectioned and stained for PCNA by an immunohistochemical procedure. Immunocytochemical staining patterns of proliferating cell nuclear antigen antigen expression permitted the recognition of G1, S, G2, M, and quiescent cells. PCNA LI, generated by scoring only cells exhibiting S-phase staining patterns, was compared to the pulse [3H]-TdR LI for each animal. Similar periportal staining patterns of S-phase nuclei were detected by both markers. The [3H]-TdR LI and the PCNA LI exhibited a peak at 24 hr of approximately the same magnitude. However, while the [3H]-TdR LI had returned to near baseline at the 48-hr time point, the PCNA LI remained elevated until the 96-hr time point. This sustained elevation of the PCNA index cannot be explained at this time.(ABSTRACT TRUNCATED AT 250 WORDS) Full text Full text is available as a scanned copy of the original print version. Get a printable copy (PDF file) of the complete article (2.0M), or click on a page image below to browse page by page. Links to PubMed are also available for Selected References . 199 200 201 202 203 204 205
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