Cancer cell biology / edited by Takeo Nagayo, Wataru Mori.

Date:
[1980]
Catalogue details

Licence: Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)

Credit: Cancer cell biology / edited by Takeo Nagayo, Wataru Mori. Source: Wellcome Collection.

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    COMPUTER ANALYSIS OF DECYCLING PROCESSES Manabu Takahashi and Michiyoshi Masuda Department of Pathology, Yamaguchi University School of Medicine* An automatic method for the analysis of decycling processes was developed to calculate decycling rate, cell loss rate, cell loss factor, birth rate or cell production rate (growth rate in no-loss condition), virtual growth rate (growth rate in non-decycling condition) and other parame ters of the cell loss process using data on the fraction of labeled mitoses (FLM), labeling index (LI), and actual growth rate (E). The basis for this analysis is the compartment model that was introduced by D. G. Kendall (10) for the multiple phase birth process. The calculation pro ceeds in conjunction with the automatic FLM curve analysis, the pro gram for which was modified from that reported previously (23). Since the cell loss rate equals the difference between the actual growth rate and the birth rate, the central problem was how to calculate the latter. A sample calculation using experimental data was presented to show that the results change appreciably depending upon the assumption as to the location of the decycling point within the cell cycle. Cell loss analysis has been an important subject of investigation for more than a decade and has added much to the knowledge of tumor growth. Of the methods now available, the one that was introduced by Steel and Bensted (20) and further refined by Steel (19) for the measurement of the cell loss factor is the most powerful tool. It involves a technique of cell labeling with tritiated thymidine, but unlike the stath- mokinetic method ( 8, 76), it uses no mitotic inhibitor which may interfere with the progression of cells through interphase or may fail to block mitoses completely. In this respect, his method seems to be advantageous over the others. However, in order that his method be applicable, the cell population must satisfy the requirements that: (1) There is no variability in phase transit time; (2) a cell leaves the cycle only at the post mitotic boundary; and (3) the specific cell loss rates in proliferative and quiescent cell compartments (P and Q compartments) are identical. Despite an increasing number of cell loss experiments there exist only a few theoretical works (4, 6, 15, 17, 19). The present report is to propose an automatic method of calculating the cell loss rate and other related parameters. The model is based on the multiple-phase birth-and-death process (22) which was developed from the model introduced by D. G. Kendall (10). The experimental data to be used are the same as in Steel's method but the way in which the data are processed is different. Because a cell loss rate equals the difference between birth rate and growth rate, our attention will be focused upon how to estimate the rate of cell flow across the mitotic boundary from the fraction of labeled mitoses (FLM) curve and the observed growth * Kogushi 1144, übe 755, Japan ¥> dfèESìtft)- 67