Cell Number Concentration

Determination of the cell number concentration (cell counting) requires that cells are suspended singly. If this is not the case in the culture, an additional step 

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There are alternatives for this measure, such as total and/or viable cell number concentration this is determined by counting cells in a given culture volume aliquot. Its determination is quite laborious and error-prone. The result is available more rapidly, but this is the only obvious advantage. However, both measures for cells are not equivalent under transient culture conditions. So-called standard cells are cells with a constant individual cell mass but these are the exception rather than the rule, see Rodin et al. [350] and references cited therein, as well as Schuster in this volume. 

Regarding the value of — logT vs. cell mass concentration, X a linear relationship was established. Values of 2T = 0.255 mg dry cell/ml which correspond to —l(>gT=0.5 could be converted via the counting with a hemacytometer to the cell number concentration, N = 4.1 x 10 cells/ml. 

Taking the fact that the cell suspension is dilute enough for granted, a relationship between the suspension turbidity, — logT and the cell number concentration, N is ... 

With the addition of increasing amounts of electrolyte this variance decreases and an approximate linear relationship between internal and external pH exists in a 1 Af electrolyte solution. The cell-0 concentration is dependent on the internal pH, and the rate of reaction of a fiber-reactive dye is a function of cell-0 (6,16). Thus the higher the concentration of cell-0 the more rapid the reaction and the greater the number of potential dye fixation sites. 

Treated rats had 1000 mg/kg FW liver (vs. 4.7 in controls) lowered hemoglobin, hematocrit, and red cell counts mean survival time of 67 days hepatic and renal histopathology Dose-time-dependent increase in copper concentrations in liver, spleen, and lung little accumulation in muscle and skin. Reduced growth at 2.5 and 3.75 mg/kg BW daily reduced survival at 3.75 mg/kg BW. Maximum copper concentrations recorded, in mg/kg FW (vs. saline controls,) were 710 in liver (<5), 212 in kidney (<10), 7 in lung (<1.5), 27 in spleen (<2.0) 6 in bone (<2.0) and 2.2 in testes (<1.6) Increased serum ceruloplasmin and white blood cell number... 

R is the ideal gas constant, T is the Kelvin temperature, n is the number of electrons transferred, F is Faraday s constant, and Q is the activity quotient. The second form, involving the log Q, is the more useful form. If you know the cell reaction, the concentrations of ions, and the E°ell, then you can calculate the actual cell potential. Another useful application of the Nernst equation is in the calculation of the concentration of one of the reactants from cell potential measurements. Knowing the actual cell potential and the E°ell, allows you to calculate Q, the activity quotient. Knowing Q and all but one of the concentrations, allows you to calculate the unknown concentration. Another application of the Nernst equation is concentration cells. A concentration cell is an electrochemical cell in which the same chemical species are used in both cell compartments, but differing in concentration. Because the half reactions are the same, the E°ell = 0.00 V. Then simply substituting the appropriate concentrations into the activity quotient allows calculation of the actual cell potential. 

Place the cursor in the A cell corresponding to the first unknown concentration (A5 in the example in step 1). Click = in upper margin. Type in the above formula for x using the cell number for the instrument readout (y) that corresponds to the A cell highlighted. For the example in step 1, for the first unknown, this would be (B5-E2)/E3. Click OK. The concentration of the unknown is now found in the A cell in which you placed the cursor (A5 for the example). 

Surfactants were tested at concentrations ranging from 0.1 mM to 10 nM dissolved in the culture medium, with the concentration of solvent always maintained below 0.1%. Results are expressed as means SD. In the proliferation yield experiments, each point represents the mean of three counts from the four culture wells. Mean cell numbers were normalised to the control, equal to 1, to correct for differences in the initial plating density. The proliferative effect (PE) was expressed as the ratio between the highest cell yield obtained with each chemical tested and the hormone-free control. Proliferation experiments were repeated at least three times. 

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