Electronic cell counter

The principle of this method is that as a cell passes through an orifice it interrupts an electric current and this interruption is picked 

The more complex machines (e.g. Coulter counter model ZM) have variable upper and lower thresholds and will measure cell number with automatic coincidence correction if required and average cell diameter or volume. When coupled with the Channelizer 256 

Coulter counter model B fitted with a model J plotter. ------------, 0 h (Go cells)  

with the publisher s permission.) These models have now been replaced with the Coulter counter model ZM with the C256 Channelyzer. 

The orifice through which the cells pass can vary in size but for animal cells the most suitable is 100 jum in diameter and 75 ju,m long and is manufactured from a ruby. The orifice tube is therefore fragile and expensive. 

---

Hematology. Hemacytometers or electronic cell counters can be used to assess the numbers of lymphocytes, neutrophils, monocytes, basophils, and eosinophils in the peripheral blood, while changes in relative ratios of the various cell types can be assessed by microscopic differential evaluation. Similar evaluations can be... 

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). 

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... 

This is considered in more detail in 10.7.5. It is a method which involves a modified electronic cell counter, i.e. a Coulter counter linked to a pulse height analyser and an electronic cell sorter. It is capable of separating cells at a rate of about 50,000/min into a... 

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. 

A miniaturized version of the conventional flask method with S. capricomutum has been developed by Blaise et al [136]. In this assay the algae are exposed to the toxicant in 96-well microplates for a period of 96 hours, after which the cell density is determined using a hemocytometer or electronic particle counter. ATP content measurements [136] or chlorophyll fluorescence [141,142] have also been proposed as test criteria. Compared to the flask method, the main advantages of the microplate assay are (a) the small sample volumes and reduced... 

Coulter WH (1956). High speed automatic blood cell counter and size analyzer. Proc. Natl. Electronics Conf. 12 1034-1040. 

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. 

We already know that the potential measured by the voltmeter is equal to the difference in the electrochemical potential of electrons in the two copper wires, marked as Cu and Cu" (cf. Eqs. 18B and 20B). What are all the potential differences that make up this measured quantity Going around the cell counter clockwise, we have... 

Electronic Zooplankton Counter. The electronic zooplankton counter (prototype) mounted on Batfish operates on a principle similar to the Coulter counter where an insulating particle, such as a zooplankter, displaces seawater in a tubular cell and causes a change of electrical con-... 

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. 

Testkits ALGALTOXKIT F (MicroBioTests Inc., Nazareth, Belgium). Specific equipment device for determination of cell concentration (e.g. electronic particle counter, microscope with counting chamber, fluorimeter, spectrophotometer, colorimeter). 

Figure 16.1 Simple dry cell battery. Electrons are conducted along the external circuit (4), which physically connects the active (2) and noble (1) materials. An equivalent ionic counter-current is conducted through the electrolyte (3), thereby completing the circuit.

---