Cell cycle 324 INDEX

For in vivo incorporation of BrdU in experimental animals, inject 10-100 mg/kg of BrdU in 0.9% saline by the ip route. A concentration of 10 mg/mL is routinely used. The animal is sacrificed after 1 h for labeling index studies or at 1-2 hourly time intervals for cell cycle progression studies In vivo incorporation of BrdU into humans at Mount Vernon Hospital involves iv injection of 200 mg of BrdU in 20 mL of normal saline as a single bolus over 3-5 min... 

R. A. Dwek. Cell Cycles, J. Murdoch Mitchison. Quantum Leaps. The DNA Code. Index. 

Because MIB-1 monoclonal antibody is used extensively to determine the cell proliferation index, its applications are discussed below. This antibody detects the nuclear antigen Ki-67 expressed in proliferating cells but not in resting cells. The antibody reacts with the nuclei of cells in mid-Gj (first gap), S (DNA synthesis), G2 (second gap), and M (mitosis) phases, but not in the G0 or quiescent phases. The use of MIB-1 antibody is one of the simplest and most reliable labeling techniques for assessing the rate of proliferation of a neoplastic cell population. Thus, the antibody can be used to assess the growth fraction (i.e., the number of cells in cell cycle) of normal, reactive, and neoplastic tissues. 

Fig. 10.12. Graphical analysis of cell cycle. 5 cm Petri dish cultures of Aedes albopictus mosquito cells were set up and the number of cells per dish counted regularly to establish the doubling time (taken as the generation time). When it was clear that the cells were growing exponentially [3H]thymidine and colcemid were added and cells processed to establish % cells labelled, mitotic index and tG2. The graph was drawn as described in the text (see 10.7.4.)...

Furthermore, cell cycle analysis by flow cytometry can be improved by using other complementary techniques that provide additional information. This is the case of the mitotic index that informs us about the number of cells undergoing mitosis during the experiment. This measurement was also recorded in our investigation, and the results indicated its excellent complementary information. 

So, these results showed a double effect of BOA on lettuce meristems an increasing significant delay in the cell cycle progression and a decrease in the mitotic index. Flow cytometry analysis showed a weak effect of BOA at cell cycle level in the step from G2 to M. BOA effect appeared to retard the cell cycle progression of treated-root meristems, which was very clear after 10 h BOA exposition (Fig. 12.5), and as an inhibition of the number of cells undergoing cell division. 

The effects exhibited in the flow cytometry analysis are also clearly detected by the mitotic index technique (unpublished data), which appears to be an excellent complementary technique in the cell cycle studies using flow cytometry. The mitotic index (see Fig. 12.5) revealed that the cell cycle progression goes slower in BOA-treated meristems than in control meristems and also that the maximum number of cells undergoing cell division is fewer and later in treated meristems (18% at 6 h BOA exposure time) than in control meristems (36% at 4 h distilled water exposure time). 

We are grateful to Dr. Marina Horjales, Dr. Nieves Redondo, and Alfonso Blanco (Faculty of Sciences, University of Vigo) for their help in the optimization of cell cycle analysis and mitotic index technique applied to lettuce. The authors also want to thank Claudia Carcamo and Oliver Weiss for their continual and valuable help in these experiments. Financial support from Ministry of Science and Technology (Spanish Government) is also acknowledged. 

Cell Cycle is a page in the Cytogenetic Terms Index. Cell cycle is defined with links to descriptions of cell division and the phases of mitosis. 

Immediately after sacrifice, bone marrow cells are collected from femurs or tibias, exposed to hypotonic treatment, fixed, spread on slides, and stained. The slides are then scored visually under the microscope. Structural chromosome aberrations should be analyzed in at least 100 metaphase cells per animal. To this end, for each cell, the number and type of aberrations (chromatid or chromosome breaks and gaps, as well as the different types of chromatid and chromosome rearrangements) should be recorded. The incidence of polyploid cells and of cells with endoreduplicated chromosomes should also be reported because they potentially reflect the induction of numerical chromosome aberrations and/or inhibition of cell cycle progression. In addition, the mitotic index, used as a cytotoxicity parameter, is calculated for 1000 cells per animal. With cytotoxic compounds, the highest dose level should induce at least a 50% reduction in the mitotic index (OECD 1997b Richold et al. 1990 Tice et al. 1994). 

Ki-67 antibodies recognize a nuclear protein involved in the proliferative portion of the cell cycle. They can be used as a measure of the growth fraction by dividing the number of positive cells by all cells present. This index roughly correlates with tumor grade and is important in the differential diagnosis of some tumors (e.g., Burkitt lymphoma). Correlations between Ki-67 index... 

Proliferation markers show nuclear antigens that appear during one or more proliferative phases of the cell cycle. A labeling index (LI), also known as a proliferation index (PI), can be derived from them. i The LI of any of the proliferation antigens is the number of antigen-positive cells divided by the total number of cells in sampled microscopic areas of the tumor. Histologic grading of astrocytomas correlates with LI. ... 

Reguera, B. et al.. Cell cycle patterns and estimates of in situ division rates of dinoflagellates of the genus Dinophysis by a postmitotic index. Mar. Ecol. Prog. Ser, 249, 117, 2003. 

The most enthusiastic reports concern the diterpenoids paclitaxel, Taxol (from Taxus brevifolia) and docetaxel, Taxotere (from Taxus baccata) having unique tri- or tetracyclic 20 carbon skeletons extracted from the bark of yew. This tree was known as a toxic plant for animals and humans for centuries. Monroe E. Wall and Mansukh C. Wani, at the Research Triangle Park (Chapel Hill, USA), identified the active principle of the yew tree in 1971. In 1979, Susan Horwitz of the Department of Molecular Pharmacology, Albert Einstein College of Medicine (New York) suggested that paclitaxel s mechanism of action was different from that of any previously known cytotoxic agent. She observed an increase in the mitotic index of P388 cells and an inhibition of human HeLa and mouse fibroblast cells in the G2 and M phases of the cell cycle. 

It is difficult to relate the effects of GA on division to a direct role of GA in the control of the cell cycle or even to prove that the enhancement of cell division by GA is not an indirect effect arising from enhancement of cell elongation (Jones 1973). GA increases the mitotic index in meristematic cells of the leaf and root of barley and in both cases a simultaneous increase in DNA synthesis occurs (Svarinskaya and Gavrilova 1976). GA may have some selective effect on the cell cycle in the barley root in this case since it reduces the duration of G, G2, and M. GA decreases the cell cycle time in the subapical meristem of dwarf waterm elon seedlings (Liu and Loy 1976) where it decreases time spent in S. The primary effect of GA in apical buds of Rud-... 

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