Cells doubling times

Tumor Type Percent of Tumors Approximate Cell Doubling Time Sensitivity to Chemotherapy and Radiotherapy Relative Risk of Metastasis... 

The cell doubling times go from less than 8 h to more than 18 h. Cells are also accumulating in G2. This is coincident with the gradual transition of String from a ubiquitously expressed product to a periodically expressed product. This transition can be largely attributed to regulation of String. 

Edgar We have done this experiment, overexpressing Myc or Ras co-expressed with String. This decreases the cell doubling time and reduces the cell size, but the... 

Derenzini M, Sirri V, Trere D, Ochs RL (1995) The quantity of nucleolar proteins nucleolin and protein B23 is related to cell doubling time in human cancer cells. Lab Invest 73 497—502 Derenzini M, Trere D, Pession A, Govoni M, Sirri V, Chieco P (2000) Nucleolar size indicates the rapidity of cell proliferation in cancer tissues. J Pathol 191 181—186 Derenzini M, Trere D, Pession A, Montanaro L, Sirri V, Ochs RL (1998) Nucleolar function and size in cancer cells. Am J Pathol 152 1291-1297... 

ATP EDTA DMSO BHK CHO HEPES mAbs B Brnax MTT PEG RNA t td WHO X adenosine triphosphate ethylenediaminetetraacetic acid Dim ethylsulf oxide baby hamster kidney cell line Chinese hamster ovary cell line N-(2-hydroxyethyl)piperazine-N -(2-ethanesulphonic acid) monoclonal antibodies specific cell growth rate maximum specific cell growth rate (3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H tetrazolium bromide) polyethylene glycol ribonucleic acid cell culture time cell doubling time World Health Organization cell concentration... 

If the cells do not all have the same generation time then the time taken to double the number of cells (TD the cell doubling time) will be slightly shorter than the generation time (7 ). Alternatively, if not all the cells in the population are growing i.e. the growth fraction is less than 1 (see below) then Tu will be longer than T. 

The time taken for the total number of cells to double (cell doubling time) is therefore not equal to the cell cycle or cell generation time. It is important, therefore, when doing cell cycle analyses to carefully distinguish between T and TD and preferably maintain the growth fraction as high as possible. 

The specific growth rate ( x) has units of reciprocal time (hr ) and can be related to the cell-doubling time (Q by the following ... 

The number of cells within each colony depends on the number of cell doublings and can be used as an estimate of the effects, if any, of the drug on the cell doubling time. A clonogenic assay can thus discriminate between cytotoxic (cell kill) and cytostatic (decreased growth rate) effects. Because a cytostatic effect may be lost upon removal of the drug a cytotoxicity assay based on colony formation is also described since this allows continuous drug exposure. 

Derenzini, M., Sirri, V., Trere, D and Ochs, R. L. (1995b). The quantity of nucleolar proteins nucleolin and protein B23 is related to cell doubling time in human cancer ceils. Lab. Invest. 73, 497-502. 

All three human lymphoblastoid cell lines responded to SAB in a similar manner. They were equally sensitive to the cytotoxic effects of SAB (Fig. 1) and to the effects of SAB on cell cycle progression (Fig. 2). Five to 10 mAf concentrations of SAB increased cell doubling times in a dose-dependent manner and decreased the plating efficiencies in the three cell lines. There was no apparent increase sensitivity to SAB in the 6TG or TFT cells. Both 15 and 20 roM SAB blocked cell cycling. In some experiments, 1 mM SAB appeared to increase plating efficiency slightly. SCE induction, measured in TK6 and 6TG cells, increased at a similar rate (Fig. S) in both cell lines. 

Fig. 2. Cell doubling time of TK6 ( ), 6TG (O), and TFT (x) cells exposed to different concentrations of 3AB. Mean of two determinations...

To analyze endogenous ADP-ribosylation, [ Hjadenosine was used as a precursor for (ADP-ribose)j, [6]. Continuous labeling for 16 h, approximately one cell doubling time... 

The inhibition of the repair process is probably not due to a trivial effect of AAB on cellular nucleotide triphosphate levels, however. When CHO-Kl cells were treated with 10 mM AAB for 1 h, there was no effect on the cellular concentration of ribonucleotides. The amounts of the ribonucleotides were 1.31, 0.97, 7.51, and 0.88 ng 10 cells for UTP, CTP, ATP, and GTP for the control cultures, respectively. For the AAB treated cells the values were 1.34, 1.01, 7.99, and 0.96 for UTP, CTP, ATP, and GTP, respectively. Whatever the mechanism, the use of AAB for slowing DNA strand rejoining may offer a novel approach for analyzing the effects of a variety of growth factors, steroids, etc., on DNA strand integrity. AAB use for this purpose may be particularly appropriate since its effects on cell growth are completely reversible for up to one cell doubling time exposure (see Sect. 6). 

CeU Lii DNA Content g/10 cells Protein Content g/10 cells Doubling Time (hr) Sister Chromatid Exchange per Chromosome... 

The effective cell doubling time net doubling time) is determined by the rate of cell production and cell loss (Begg and Steel 2002). Therefore, accelerated repopulation of tumour stem cells during radiotherapy could result from an increased production rate or reduced... 

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