When I worked in cell cycle project, I needed a formula to calculate the cell cycle duration from time of doubling the number of cells, if some of the cells was in G0 (exit from cell cycle), I did not find this formula in the literature, and then got it myself: T = td / log 2 [(2 - y) / (1 - y)] (Uzbekov et al., 1999; Uzbekov, 2004) td – time of cell quantity duplication, T – cell cycle duration, y – part cells in G0 phase. (in "log2" - "2" is index)
Maybe someone has seen this formula before 1999?
The simplest approach is to subtract the number of the G0 cells from your data and then commute the growth rate of the dividing cells from the data. For example, if you count the number of cells at times t = [t1, t2, ... tn] and find counts c = [c1, c2, .. cn], the number of non-dividing cells should be a constant that you can subtract from the counts of all cells, i.e., cc = c - number_of_non-dividing_cells. Then you can compute the growth rate simply by regressing log(cc) on the time t and from the growth rate the doubling time as td = log(2) / growth_rate.
The real situation with the balance between the cells in the cycle and in the G0 phase is very compex. The proportion of cells in the G0 increases with spending growth factors from cell culture medium, due to the increasing of contact inhibition, and so on. Some of these factors, I examined in my papers in 1999-2004. My question was not about different methods of calculation, but about is my formula really original, or someone else has used it before me.
Counting cells in a certain area periodically in the microscope is very simple method, as simple to determine the proportion of cells in the G0 from inclusion of BrDU (long incubation). Thus this formula can be useful for analyzing the duration of the cell cycle after different experimental treatments (separately from Go part increasing).
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