Kinetic cell growth

Stable protein Intracellular protein Non-toxic protein Known infection kinetics/cell growth rate Only low-titer/limited virus stocks available Bioreactor operation at high infection cell densities at or beyond 1-2x10 cells mL (fed-batch processes) Unstable protein Secreted protein Toxic/growth-retarding protein Unknown infection kinetics/cell growth rate Concentrated virus stocks available Bioreactor operation at medium to low cell densities (batch processes)... 

Product formation kinetics in mammalian cells has been studied extensively for hybridomas. Most monoclonal antibodies are produced at an enhanced rate during the Gq phase of the cell cycle (8—10). A model for antibody production based on this cell cycle dependence and traditional Monod kinetics for cell growth has been proposed (11). However, it is not clear if this cell cycle dependence carries over to recombinant CHO cells. In fact it has been reported that dihydrofolate reductase, the gene for which is co-amplified with the gene for the recombinant protein in CHO cells, synthesis is associated with the S phase of the cell cycle (12). Hence it is possible that the product formation kinetics in recombinant CHO cells is different from that of hybridomas. 

Monod kinetics Kinetics of microbial cell growth as a function of substrate concentration proposed by Jacques Monod and widely used to understand growth-substrate relationships. 

For type 3 processes, growth and metabolic activity reach a maximum early in the batch process cycle (Figure 3.1) and it is not until a later stage, when oxidative activity is low, that maximum desired product formation occurs. The stoichiometric descriptions for both type 3 and 4 processes depend upon the particular substrates and products involved. In the main, product formation in these processes is completely uncoupled from cell growth and dictated by kinetic regulation and activity of cells. 

Table 3.1 shows the kinetic parameters for cell growth, rate models with or without inhibition and mass transfer coefficient calculation at various acetate concentrations in the culture media. The Monod constant value, KM, in the liquid phase depends on some parameters such as temperature, initial concentration of the carbon source, presence of trace metals, vitamin B solution, light intensity and agitation speeds. The initial acetate concentrations in the liquid phase reflected the value of the Monod constants, Kp and Kp. The average value for maximum specific growth rate (/xm) was 0.01 h. The value... 

The kinetic of cell growth for prediction of growth rate is projected by the net growth rate, which is ... 

The parameters of the Monod cell growth model are needed i.e. the maximum specific growth rate and the Michaelis-Menten constant are required for a suitable rate equation. Based on the data presented in Tables 10.1 and 10.2, obtain kinetic parameters for... 

A limiting case of Monod kinetics has Ks = 0 so that cell growth is zero order with respect to substrate concentration. Rework Example 12.7 for this situation, but do remember to stop cell growth when S = 0. Compare your results for X and p with those of Example 12.7. Make the comparison at the end of the exponential phase. 

Effect of Temperature on Insect Cell Growth Kinetics... 

A very versatile piece of equipment that is affordable for individual laboratories is the microplate reader. This allows multiple samples to be analyzed at once, commonly in a 96-well format, although 384- and 1536-well formats are available. Typical measurements that can be performed include UV-Vis absorbance, fluorescence, or luminescence, allowing a range of assays to be performed, such as cell growth, enzyme kinetics, enzyme stability, or enzyme-linked immunosorbent assay [60-62]. Functionality can be increased by the use of liquid dispensing systems or automatic plate handling. 

The kinetics of cell growth/death under free and/or immobilized states assume a relevant role in the assessment of the amount of biophase present in the reactor. Obviously, the kinetics depends strongly on the carbon/energy source available in wastewaters or purposely added. With the exception of consortia collected from anaerobic digesters, single strain cultures used in azo-dye conversion are characterized by hindered growth under anaerobic conditions [26, 29, 41], For these biosystems, the duration of the anaerobic stage must be carefully monitored to preserve cell viability. 

Ennaoui, A. Weber, M. Saad, M. Harneit, W. Lux-Steiner, M. Ch. Karg, F. 2000. Chemical bath deposited Zn(Se,OH)x on Cu(In,Ga)(S,Se)2 for high efficiency thin film solar cells Growth kinetics, electronic properties, device performance and loss analysis. Thin Solid Films 361-362 450 153. 

The subject of biochemical reactions is very broad, covering both cellular and enzymatic processes. While there are some similarities between enzyme kinetics and the kinetics of cell growth, cell-growth kinetics tend to be much more complex, and are subject to regulation by a wide variety of external agents. The enzymatic production of a species via enzymes in cells is inherently a complex, coupled process, affected by the activity of the enzyme, the quantity of the enzyme, and the quantity and viability of the available cells. In this chapter, we focus solely on the kinetics of enzyme reactions, without considering the source of the enzyme or other cellular processes. For our purpose, we consider the enzyme to be readily available in a relatively pure form, off the shelf, as many enzymes are. 

The growth rate of cells is taken proportional to the cell concentration, x, and to an empirical form of the dependence on the concentration, p, of the nutrient. That empirical form was assumed by Monod (1942) to be the same as in the Michaelis-Mewnten model for enzyme kinetics. This makes the rate of cell growth,... 

Here rx is the rate of cell growth (kg cell m 3 s 1), X is the cell concentration (kg cell m 3) and k is a kinetic growth constant (s 1). For a batch system, this is equivalent to... 

Many other kinetic forms have been proposed and have been used in the past however, they have all been forgotten since Monod came out with his expression. Its simplicity won the day. So we will use this type of expression throughout to relate the rate of cell growth to substrate concentration. 

The most reasonable approach for addressing this dilemma is to exploit differences in cell growth kinetics between cancer cells and host cells. A hallmark of cancerous cell growth is the rapidity of its cellular proliferation. At any given time, a malignant tumor should have more cells undergoing mitosis and replication than other tissues in the host. 

The kinetics of cell growth was discussed in Chapter 4. By combining Equations 4.2 and 4.6, we obtain ... 

Understanding the growth kinetics of microbial, animal, or plant cells is important for the design and operation of fermentation systems employing them. Cell kinetics deals with the rate of cell growth and how it is affected by various chemical and physical conditions. 

While the Monod equation is an oversimplification of the complicated mechanism of cell growth, it often adequately describes fermentation kinetics when the concentrations of those components which inhibit the cell growth are low. 

Table 6.1 shows the ACSL program and Figure 6.6 shows the results. Comparison of Figure 6.6 with Figure 6.1 shows that Monod kinetics can predict the cell growth from the start of the exponential growth phase to the stationary phase. 

A strong similarity is found for the present blends with a PPE/PS ratio of 50/50, as reflected by a similar bimodal cell size distribution for all SAN contents. Small differences can be related to the distinct foaming kinetics of the PPE/PS blend phase. Compared to the PPE/PS 75/25 blend phase, the higher content of PS in the PPE/PS 50/50 phase leads to a cell nucleation and growth kinetics close to the SAN phase. Nevertheless, the PPE/PS phase still appears to restrict the cell growth and expansion in the SAN phase to some extent, and smaller cells are found within the cell walls. Independent of the SAN content, cell growth within the dispersed SAN phase proceeds under the constraints of the continuous, higher Tg PPE/PS phase. 

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