Showing papers by "Per E. Schwarze published in 1988"

The polyploidizing growth pattern of normal rat liver is replaced by divisional, diploid growth in hepatocellular nodules and carcinomas

Abstract: DNA content was measured by flow cytometry in isolated nuclei from 71 neoplastic nodules and 15 hepatocellular carcinomas isolated from rat liver at various times after treatment with an initiation--promotion regimen employing diethylnitrosamine and 2-acetylaminofluorene. Nodules and carcinomas contained mostly diploid nuclei as compared with both surrounding and normal hepatocytes which were predominantly polyploid. There appears to be a positive correlation between the degree of diploidy in nodules and their rate of proliferation. No aneuploid populations were identified in any neoplasm despite good peak resolution. These results show that an alteration in proliferation pattern from normal polyploidizing growth to diploid--diploid divisional growth is a consistent characteristic throughout the carcinogenic process in our experimental model.

Shift from polyploidizing to nonpolyploidizing growth in carcinogen-treated rat liver.

Abstract: Liver growth patterns in normal and carcinogen-treated young Wistar Kyoto rats were analyzed in terms of absolute hepatocyte numbers and ploidy distributions, calculated from DNA measurements made by flow cytometry and microscope counts of binucleated cells Polyploidizing growth was observed during normal liver development, dominated by progressive polyploidization and a decrease in the number of diploid cells Nonpolyploidizing growth was seen during liver regeneration and after treatment with 2-acetylaminofluorene (AAF) This mode of growth was characterized by an increase in all mononucleated ploidy classes in the absence of net polyploidization (no increase in binucleated cells) Additional diploid proliferation was detected after initiation with diethylnitrosamine followed by promotion with AAF This selectively expanding diploid hepatocyte population, which persisted after AAF withdrawal, could represent the AAF-promoted progeny of diethylnitrosamine-altered cells with constitutive nonpolyploidizing growth properties

2-Acetylaminofluorene promotion of liver carcinogenesis by a non-cytotoxic mechanism.

Abstract: 2-Acetylaminofluorene (AAF), given in the diet at 0.02% for 4 weeks, is an effective promoter of liver carcinogenesis initiated by partial hepatectomy (PH) plus diethylnitrosamine (DEN) in the inbred rat strain Wistar Kyoto. AAF promotes the early (6 week) appearance of phenotypically altered (gamma-glutamyltranspeptidase-positive) cells as well as the later appearance of neoplastic nodules (2-4 months) and hepatocarcinomas (4-8 months). Promotion does not seem to involve selective cytotoxicity (selection of AAF-resistant hepatocytes), since neither AAF alone nor DEN + AAF has any inhibitory effect on overall liver growth.