Electronic cell counting

Fig. 11. Synchronization with eight shocks. Population increases were followed by electronic cell counting. Log cells/ml are plotted against time after EH to two separate experiments, A and B. Untreated controls (I). Methotrexate + uridine from shock 2, thymidine at EH — 55 minutes (II A) or at EH + 30 minutes (II B). Methotrexate + uridine from shock 2, no thymidine (III). (From Zeuthen. 1970. Exp. Cell Res.. 61 311 -325.)...

Fig. 21. Free-running synchrony by four heat shocks (upper continuous curve) and restricted repetitive synchrony by four to five heat shocks (upper continuous curve extended by dashed curve). Results of electronic cell counts and of chemical analyses refer to the restricted system at the end of shock 5 (7.2 x 10 cells/ml) DNA 12.5 RNA 344 protein 3,330 ju/ig/cell. Tetrahymena cells synchronized repetitively and under restricted conditions are of almost the same size as are normally growing cells. This will be apparent from comparison of the figures just presented with those in the legend accompanying Figure 11 in the review by Zeuthen Rasmussen, 1971.

Particles with a diameter of =1 pm are difficult to count in a standard counting chamber and may require the aid of an electronic cell counter, such as the Coulter Counter (model ZBI). 

Cell concentration in suspension can be determined through an optical microscope employing a hemocytometer for manual cell counting, or in a semi-automatic way using an electronic particle counter (such as a Coulter counter), as described in detail by Freshney (2005). Through dye exclusion (such as trypan blue), it is possible to determine viable cell concentration, that is the number of cells in a known sample volume capable of proliferating in favorable culture conditions. 

Fig. 3.8. L929 cells were seeded in 100 ml GMEM with 10% calf serum at 3 cells per microcarrier bead onto 5 x10s Cl-(Cytodex 1), P(Biosilon) or G (Bioglas) beads. The cell number was estimated by releasing the cells with trypsin, briefly allowing the beads to settle and counting the cells with a Coulter counter. Difficulty was encountered releasing the cells from Cytodex, but cells attached only weakly to the glass and particularly to the plastic beads and many cells were free in suspension. The use of electronic cell counters is not recommended for counting cells released from microcarriers as the orifice occasionally becomes blocked by small microcarriers in the...

Fig. 7.2. Diagrammatic representation of an electronic cell counter. When the upper tap is open the vacuum pump draws the mercury into the position shown in black (lower position). On closing the tap the mercury slowly returns to its equilibrium (upper) position and while so doing it draws cell suspension through the small orifice. As a cell passes through the orifice it interrupts the current flowing between the two electrodes and each cell is registered on an oscilloscope and is counted. The count is recorded as the mercury sweeps out the volume between the switches (usually 0.5 ml).

The electronic cell counter is, however, more reproducible. As many thousand cells are counted, machine sampling errors are very small and errors of less than 5% are easily achieved. The main source... 

Resuspend the cells in F/20 medium, 4 mL/femur and count the nucleated cells in a hemocytometer after staining with methylene blue, or count the cells on an electronic cell counter after first lysing the red cells with Zapoglobin. Each femur will yield 10-15 x 106cells. 

Automation of cell counting (total cells) is possible with electronic counters, especially for non-clumping single suspension cells. A method that is widely used for total cell numbers is counting cell nuclei after dissolving the cytoplasm. This is particularly useful for large clumps of cells, where cells are inaccessible (e.g. in matrices) or where cells are difficult to trypsinize off substrates (e.g. microcarriers). If determination of viability is the prime consideration, then the most accurate method is to count the cells that have the ability to divide by the mitotic index method. 

Depending upon the test organism, between 2 X 104 and 5 X 104 cells are used to inoculate the test vessel and the concentration of cells is determined daily. Cell counts are made daily by using a hemocytometer or an electronic particle counter such as the Coulter Counter. Chlorophyll can be measured spectrophotometrically or fluorometrically. The fluorometric determinations are more accurate at low concentrations of test organism. Other measurements that have been used include DNA content, ATP charge, and 14C assimilation. 

Hemoglobin was determined by the absorbance at 540 a of a 1 200 dilution of blood with 0.4% ammonium hydroxide. An electronic counter (Coulter) was used to determine the red cell counts In different parts of this work, the liver iron was determined spectrographically, with the ferrozine method (2) or with the use of 2,4,6-tripyridyl-l,3,5-triazine (10). Further experimental details, including identity of cereals involved, can be found in the initial reports (1, 3, 5 y 6, T). 

There is an evolving concern about the use of some particular organophosphates such as tricresyl phosphate, tri-n-butyl phosphate, and triphenyl phosphate [94,108-110]. Animal studies have shown that these phosphate esters can cause allergies, learning problems, and deterioration in sperm production and can influence the white and red blood cell counts of humans [109]. In a recent publication [110], levels of flame retardants in indoor air at electronics scrap recycling plant and other work environments were considered 15 brominated FRs and 9 organophosphorus compounds were analyzed. Although the measured concentrations found in all... 

With large battery arrays, something as seemingly simple as the connection sequence of the cells to the electronics system can be destructive. In lower cell-count systems, the cell connection sequence can be easily controlled during the assembly process connect the lowest cell negative first, then the positive, then the next most positive cell, etc.—on up to the top of the cell-stack. This is simple for cell arrangements up to 10 or 20 cells in series, but may be excessively costly during assembly of a cell pack of hundreds of cells. 

P. Crosland Taylor, J.W.Stewart, G.Haggis, An electronic blood cell counting machine, the American society of hematology. 2021 L St, NW, Suite 900, Washington DC. 

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