Cells wash-out

Yabannavar et al. [89] employed Eq. (11) to calculate the maximum perfusion flow rate attainable before cell wash-out, which occurs when cell growth is compensated by cell passage through the spin-filter or, according to Eq. (12), when Fapp = 0- Under these conditions ... 

The maximum operational perfusion rate Dmax is thus just marginally lower than that which results in cell wash-out. Therefore, when working with Dmax, the cell loss in the perfusate is totally compensated by the cell growth. In this situation, the apparent specific cell growth rate Pap is zero. Hence, from Equation (21) ... 

Tracer preloaded in the endothelial cells washes out rapidly because... 

Laser Repetition Rate and Cell Wash-Out Time The pulse mixing and signal tailing that are induced during the aerosol transport is a common limitation of LA-ICP-MS in terms of depth profiling resolution. In order to avoid any mixing of information... 

As the dilution rate increases, the concentration level of final substrate will linearly increase with D, and D approaches p.m lx. The result of a high dilution rate would cause the cell density to drop. When D = p.max, X = 0. This phenomenon is known as wash out. 

Neai the wash out, the reactor is very sensitive to variations of dilution rate D. A small change in D gives a relatively large shift in X and S. The rate of cell production per unit volume of reactor is DX. These quantities are shown in Figure 6.5, where there is a sharp maximum in the curve of DX. We can compute maximal cell rate by taking the derivative of DX with respect to D, then solving the equation. The derivative of DX with respect to D is defined as ... 

There is an interior optimum. For this particular numerical example, it occurs when 40% of the reactor volume is in the initial CSTR and 60% is in the downstream PFR. The model reaction is chemically unrealistic but illustrates behavior that can arise with real reactions. An excellent process for the bulk polymerization of styrene consists of a CSTR followed by a tubular post-reactor. The model reaction also demonstrates a phenomenon known as washout which is important in continuous cell culture. If kt is too small, a steady-state reaction cannot be sustained even with initial spiking of component B. A continuous fermentation process will have a maximum flow rate beyond which the initial inoculum of cells will be washed out of the system. At lower flow rates, the cells reproduce fast enough to achieve and hold a steady state. 

After each series of experiments with beams of various intensity the section plate would be removed from the cell and disassembled, with radioactive silver washed out by nitric acid. Radioactivity of the solutions obtained was measured by a multichannel spectrometric scintillation y-counter with sensitivity of up to 10 G, i. e. around 10 of atoms which, according to calculations, is 10 times lower than sensitivity of ZnO sensor 10 G or 10 of Ag atoms respectively [28]. This difference in sensitivity lead to great inconveniences when exposing of targets was used in above methods. Only a few seconds were sufficient to expose the sensor compared to several hours of exposure of the scintillation counter in order to let it accumulate the overall radioactivity. It is quite evident that due to insufficient stability during a long period of exposure time an error piled up. 

Step 2. Instrumental isolation out of liquid culture media of individual cells. Step 3. Automated cell washing and cell suspension normalization to standard... 

Aerobic phase. Technical air and liquid medium were continuously fed to the airlift during the aerobic phase. Gas flow rate was set at 5 nL/h corresponding to 0.64 vvm. The feeding rate of the phenol-bearing (200 mg/L) stream was set at 20 mL/h, that is D 0.15 h The dilution rate was set at a value larger than the maximum grow rate (wash-out conditions with respect to free cells), 0.14 h"1 [60]. 

Taylor The experimental observation from which this comes is as follows. First, we pretreat the permeabilized cells in our superfusion apparatus with 100 /rM Ca2+ for about a second, to drive the cells to the state where they can no longer respond to InsP3 (even at heroic concentrations). Next, we wash out the Ca2+ to a low cytosolic level of 200 nM. Then we look for how long it takes for the normal response to a maximal concentration of InsP3 to recover. That takes a long time. 

Mitochondria are distinct organelles with two membranes. The outer membrane limits the organelle and the inner membrane is thrown into folds or shelves that project inward and are called cristae mitochondriales. The uptake of most mitochondrion-selective dyes is dependent on the mitochondrial membrane potential. Conventional fluorescent stains for mitochondria, such as rhodamine and tetramethylrosamine, are readily sequestered by functioning mitochondria. They are, however, subsequently washed out of the cells once the mitochondrion s membrane potential is lost. This characteristic limits their use in experiments in which cells must be treated with aldehyde-based fixatives or other agents that affect the energetic state of the mitochondria. To overcome this limitation, the research... 

Therefore now the most perspective for cryopreservation of cord blood NCs is the designing of freeze-thawing methods with no washing-out using cryoprotectants, non-penetrating into a cell. 

As a result of performed by us fundamental studies there was developed a new cryopreservation method with no washing-out for cord blood NCs, it is based on use of non-penetrating PEO-1500 cryoprotectant in combination with cold treatment of cells before freezing and special own two-step freezing program. 

Developed method with no washing-out allows the preserving after thawing (Fig. 2) more than 75% of CD 45 - cells and up to 85% CD 34 -cells. 

Once a series of samples is placed on the carousel, the analysis proceeds automatically with a cycle of approximately 3 minutes (including complete wash-out of the previous samples). When a representative sample flUs the two detector cells, the flow is stopped and the measurements are collected from the instruments. When stable readings are obtained, they are compared with the data on file for the sample type and then presented to the analyst for acceptance. Measurements for colour are also possible with suitable changes in the design. Figure 7.2 shows the communication hnes required and the protocols necessary to consolidate and operate the system. Such a system has been in operation on a routine basis for several years in a major fragrance and flavour company in the UK. 

When the system which was to be linked to the autosampler system was purchased, it was found that the conductivity cell was excessively large and primarily designed to be fitted to a A" pipehne for analytical purposes this was clearly too large. However, the pH cell provided an Ingold standard electrode system with dimensions which allowed it to be placed within the conductivity sensor, as shown in Fig. 7.21. It is therefore possible to configure a flow cell in which the conductivity sensor houses the pH electrode. The latter also serves to take up most of the cell volume so that the wash-out requirements are not too excessive. The cell is filled by taking a sample from the autosampler with pump 1 hquid fills the cell and overflows via the weir arrangement and the top of the cell. 

The way in which the active microzone is retained also depends on its relationship to the detector (Fig. 2.6) and the type of interaction with the analyte or its reaction product. If the microzone is an integral part of the probe, an additional support (usually a membrane) is often required, so contact with the sample is hindered to some extent. On the other hand, a microzone located in a flow-cell can be retained in various ways. Thus, if the microzone consists of a porous solid or particle, the flow-cell is simply packed with two filters in order to avoid washing out (e.g. see [21]). Too finely divided solids (viz. particle sizes below 30-40 pm) should be avoided as they require pressures above atmospheric level, which complicates system design and precludes use of microzones with a high specific surface. Placing a separation membrane in a flow-cell is... 

Cell cytometry is a technique to determine the populations of cells in particular parts of their metabolic cycles. One places the cells in a medium containing nutrient molecules that have been tagged with fluorescent dyes. The nutrient is then washed out and fluid containing the cells is passed through a capillary, where UV light is used to make the dye molecules within the cells fluoresce. The capillary has a valve downstream that switches to allow the fluorescing cells to be collected in another flask to concentrate them. 

Hansen et al. [76] used a siliconized modified 300 mb Erlenmeyer flask as an external settling device, with its undersize at 45° to the vertical. The flask was isolated to maintain the temperature at 37°C. The low separation capacity of this adapted flask limited the perfusion rate to a maximum of 1.0 d otherwise the cells would be washed out. 

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