Linked Life Data

9744539

Source:http://linkedlifedata.com/resource/pubmed/id/9744539

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
8
pubmed:dateCreated
1998-9-24
pubmed:abstractText
2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) is a potent tumor promoter in two-stage initiation-promotion models and induces cell proliferation and development of enzyme-altered hepatic foci. It is believed that increased cell proliferation is a necessary step in carcinogenesis. Therefore, the analysis of the effect of TCDD on cell proliferation in rat liver may aid in the understanding of the mechanism of hepatocarcinogenesis induced by TCDD. The aim of this study was to investigate the time course and reversibility of cell proliferation in non-initiated and diethylnitrosamine-initiated female rats exposed biweekly to a daily averaged dose of 125 ng TCDD/kg/day for up to 60 weeks. In addition we evaluated the suitability of different dose metrics for the evaluation of TCDD-induced changes in cell proliferation and CYP1A1 enzyme induction. Cell proliferation was measured as the incorporation of 5-bromo-2'-deoxyuridine (BrdU) into hepatocytes undergoing replicative DNA synthesis. Mean BrdU labeling indices in TCDD-treated animals were not increased over controls after 14 weeks exposure, but were increased 8- and 2-fold after 30 and 60 weeks' treatment respectively, despite similar liver levels of TCDD at all these times (23-30 p.p.b.). In comparison, CYP1A1 activity, as measured by ethoxyresorufin deethylase activity, was significantly induced at all times points analyzed. Sixteen weeks following cessation of TCDD treatment, labeling indices were still significantly elevated over controls, but after 30 weeks of withdrawal, labeling indices were no different from controls, indicating that TCDD-induced changes in cell proliferation were reversible. Dosimetric analysis indicated that rat liver tissue burden was suitable for prediction of CYP1A1 expression but not cell proliferation and that the area under the curve was unsuitable for prediction of both TCDD-induced changes in CYP1A1 expression and cell proliferation.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Aug
pubmed:issn
0143-3334
pubmed:author
pubmed:issnType
Print
pubmed:volume
19
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1427-35
pubmed:dateRevised
2004-11-17
pubmed:meshHeading
pubmed:year
1998
pubmed:articleTitle
Differences in kinetics of induction and reversibility of TCDD-induced changes in cell proliferation and CYP1A1 expression in female Sprague-Dawley rat liver.
pubmed:affiliation
Laboratory of Computational Biology and Risk Analysis, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, USA. walker3@niehs.nih.gov
pubmed:publicationType
Journal Article