Cells cell viability

For purposes of quality control, any cell preparation used in the screen (see below) needs to have a definitive or consensus diagnosis and grading determined by histological examination. Furthermore, tumor cell preparations must be at least 80% tumor cells (as determined by cytopathological examination), whereas normal cell preparations must be devoid of any tumor cells. Cell viability, determined by trypan-blue exclusion, must be a minimum of 70%, and the signal-to-noise ratios for a predetermined cell cluster concentration must be at least threefold. 

The methods and technology used for quality control and the quantity of parameters checked can vary, depending on the cell type preparation and the final use of the cells. Cell viability, morphology, and proliferative capacity are common, easily tested parameters. Immunofluorescence studies with panels of antibodies raised against specific markers of the isolated cell type are commonly employed to provide proof of the identity and health of the cells. Additional tests, for example, specific enzymatic activity or expression levels of particular genes, can be also performed as routine quality control parameters when they are crucial to the subsequent use of the cells. 

Compounds Cells Cell viability % (concentration of the compounds) References... 

The most important function of electroporation is transfection, i.e., inserting the biological nanosamples into the living cell. Cell viability and transfection rate are the two most important indicators to evaluate the functionality of these microfluidic electroporatiOTi devices. The applied electric pulse must be ctuitroUed carefully. While the nanosample insertitHi should be as successful as possible, the viability of the cell may not be affected by applied external electric pulse. Compared with the cell lysis, the cell transfection usually performs by q)plying lower external electric field. 

Figure 15.4 shows the linear model for (15.6.3), the loss of cell viability at various temperatures. As the temperature increases from 105 to 121 °C, the value for the slope of the line increases. This means that the number of viable cells at a fixed time of sterilisation will drastically decrease as the temperature increases by 16 °C. 

In contrast to the DNA damage checkpoint, the mitotic spindle checkpoint is essential for cell viability. Dierefore, targeting kinases of the spindle checkpoint including Bubl, BubRl, and Mpsl might be a valid strategy for anticancer treatment. 

Constitutive exocytosis/secretion takes place in all eukaryotic cells and is essential for cell viability and growth. Trafficking vesicles destined for constitutive exocytosis originate from the trans-Golgi-network and contain secretory macromolecules derived from the... 

In order to assess the effect of the corn cob xylan on the cell viability and proliferation rate, xylan solutions at concentrations of 0.1, 0.25, 0.50, 0.75, and 1 mg/ml were placed in contact with human cervical adenocarcinoma cells (HeLa cells) for 24 and 72 h. Finally, the cell viability was determined by the MTT assay. It was observed that regardless of the xylan concentration, the samples tested did not affect the viability of HeLa cells after incubation for 24 h (Figure 13) (Unpublished data). 

Besides, the statistical analysis of the results obtained confirmed that the xylan samples did not present a significant effect on the cell viability and cell proliferation rate when in direct contact with HeLa cells at the concentrations used in this study and compared to the control. 

The biological impact of starch capped copper nanoparticles on mouse embryonic fibroblast (3T3L1) cells in vitro) was also evaluated by various parameters. More than 85 % of the 3T3Llcells were found to be viable, even after 20 hours time exposure which implies minimum impact on cell viability and morphology. The study demonstrates dose dependent cytotoxic potential of SCuNPs, that is non cytotoxic in the nanogram dose and moderately cytotoxic in the microgram doses (Fig. 10). Comparison of SCuNPs with Cu ions and uncapped copper nanoparticles (UCuNPs) revealed that, ions are more cytotoxic than SCuNPs. This observation supports the theory of slow release of ions from starch coated nanoparticles. 

Fig. 10. Effect of starch capped copper nanoparticles on cell viability (MTT assay) in case of mouse embryonic fibroblast (3T3L1).

Table 3. Effect of AR concentration ICHM on the saving of E.coU recA y.lux cell viability and relative index of SOS-system induction at UV exposion (3.64 J/m ). - P<0.05 - P<0.01.

So this research reveals new mechanisms of bacterial autoregulation under extreme conditions, controlled by low weight molecules - alkyiresorcinols. It applied aspects are defined by developing of methods for DNA protection in vitro and elongators of bacterial cells viability at UV exposure. 

Drought is perhaps one of the most complex examples to choose but it illustrates well the possibilities of, and pitfalls to, progress. Drought affects almost every facet of plant function and we are faced with the paradox that yield and evapotranspiration are intimately linked. In general, increases in yield when water supply is limiting are likely to result from characteristics which increase the available water supply, increase water use efficiency or increase biomass allocation to the economically useful plant parts (Pass-ioura, 1986). Additionally, features which maintain cell viability and protect metabolism in water-stressed tissue and allow rapid recovery after dry periods will contribute yield under some circumstances. 

Cationic aPNAs are taken up into living cells in a dose-dependant manner without affecting cell viability. (4) We have shown that aPNAs are stable to the nucleases present in human semm for up to 6 h. 

Fig. 15. Effects of turbulent shear stress level and exposure time on cell viability measured by trypan blue staining. Cells were sheared in a concentric cylinder viscometer [1]...

Models based on Eqs. (47)-(50) have been used in the past to describe the disruption of unicellular micro-organisms and mammalian (hybridoma) cells [62]. The extent of cell disruption was measured in terms of loss of cell viability and was found to be dependent on both the level of stress (deformation) and the time of exposure (Fig. 25). All of the experiments were carried out in a cone and plate viscometer under laminar flow conditions by adding dextran to the solution. A critical condition for the rupture of the walls was defined in terms of shear deformation given by Eq. (44). Using micromanipulation techniques data were provided for the critical forces necessary to burst the cells (see Fig. 4)... 

The influence of mechanical forces on cell viability is of great importance when growing the cells in agitated systems. By far the greatest amount of work reported in the literature has been done on suspension cells but adherent cells also experience shear forces not only in bioreactors also in vivo. Therefore, most research has be done on endothelial cells but studies exists done on non-endothelial cells. The influence of shear forces on cell growth, morphology and productivity will be discussed as well as possibilities of making the cells more resistant. 

The main reasons for the damage to cells in a reactor are the apparent shear forces and the collision of microcarriers with themselves and with turbulent eddies. In the literature studies are mainly focused on suspension cells and there again on hybridoma cells. The work reported in the hterature can be divided into two fields studies dealing with the influence of various stirrer speeds on cell viability and those investigating the influence of defined shear forces on cells with a viscosimeter. 

A dual isotope labeling technique [85] has been used to measure membrane permeability in plant cells, based on the selective permeabiHty of the membranes of living cells to tritiated water and carbon-14 labeled mannitol. Kieran [29] showed that the results of the dual isotope labeling and Evan s Blue staining methods correlated well as indicators of cell viability however, the latter was preferable in terms of reagent cost and ease of analysis. 

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