DNA Ploidy Measurements Research Articles

Hemangiopericytoma of the orbit: Nuclear DNA patterns studied by flow cytometry

The biological behavior of orbital hemangiopericytoma cannot be determined with certainty microscopically. Because of this lack of correlation between the histopathologic features and clinical outcome, extracted nuclei from 12 hemangiopericytomas of the orbit were studied with flow cytometry in an attempt to determine whether such a study could be used to determine prognosis. Paraffin-embedded blocks were used to perform the nuclear DNA ploidy studies after preparation with the Hedley technique and the Vindeløv method of staining. the clinical records were reviewed with specific attention to surgical details, recurrence, and tumor-related deaths. the flow cytometric DNA ploidy measurements of isolated nuclei showed a diploid pattern in the 12 tumors studied. Thus, this investigation failed to provide prognostic information. Complete surgical removal of the tumor remains an important factor governing the prediction of clinical behavior.

Cell cycle distributions, growth characteristics, and variation in prolactin and growth hormone production in cultured rat pituitary cells

Clonal strains of rat pituitary tumour cells (GH3 cells) spontaneously produce and secrete prolactin and growth hormone. Chromosome analysis and DNA ploidy measurements revealed that the GH3 cells in the present study were triploid and had a decreased chromosome number compared to the parent strain. Monolayer cultures of these cells grow exponentially for 6-7 days with a mean doubling time of 54 h. Cell cycle distributions and phase durations were determined by micro-flow fluorometric measurements of cellular DNA content combined with computer calculations. During exponential growth the cell cycle distribution did not change (65.4% cells with a G1 phase DNA content, 24.9% with an S phase DNA content, and 9.7% with a (G2 + M) phase DNA content). Counting of mitoses gave 1.4% cells in M phase. The 3H-Tdr labeling indices were determined by autoradiography, and the results were in good agreement with the number of cells in S phase as calculated by micro-flow fluorometry. The phase durations were: Ts=15.9 h, TG2=6.2 h, TM=1.1 h, and TG1=30.9 h. TS and TM calculated from 3H-Tdr labeled and Colcemid treated cultures gave corresponding results. In plateau phase cultures the number of cells with a G1 DNA content increased to 80% and the number of cells with an S phase DNA content decreased to between 5% and 10%. The specific production of prolactin and growth hormone determined by radioimmunoassay showed two and four-fold increases respectively, during exponential growth. The hormone values decreased to initial or subinitial values (day 2 values) when approaching plateau phase. We conclude: that changes in the cell cycle distribution of the cell population cannot be responsible for the spontaneous alterations in hormone production during growth and that most of the hormone-producing cells must be in the G1 phase.