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Biomedical subjects

M O Toll

Publications and source records attributed to M O Toll.

4 recordsLinked to original sources

A low cost microprocessor-controlled electrofusion and electroporation system.

An important recent development in the field of biotechnology has been the use of high electric fields to render cell membranes temporarily permeable (electroporation). Cells in this state are receptive to gene transfer or can be induced to fuse with each other (electrofusion) to form hybrid cells containing the combined characteristics of the parent cells. A major reason for fusing cells is to form hybridoma cells which secrete monoclonal antibodies. A problem for research workers has been the high price of some of the electrofusion equipment. This problem has been addressed by designing a device that is inexpensive (less than $800 Canadian) and can be assembled by an electronics technician. The system uses a Radio Shack CoCo III microcomputer which is programmed in BASIC and controls the electroporation voltage pulse amplitude (25-500 V) and duration (2-275 microseconds) to an electrofusion chamber; this yields electric field strengths of 0.25-5 kV cm-1 for a 0.1 cm electrode spacing. The system is capable of delivering pulse currents up to 3 A. This paper provides technical details on how to construct an instrument that has greater flexibility at less cost than comparable commercially available instruments.

Biotechnology

Isometric dynamic response of mammalian heart muscle due to step changes in the calcium concentration of the perfusing medium.

The isometric tension transient response of isolated kitten papillary muscle was found to exhibit direction-dependent dynamics when subjected to step changes in the calcium concentration of the bathing medium. The tension transient curves could be resolved into a minimum of two to three exponential components, which could be considered to indicate different calcium compounds or compartments within the muscle. However, a model relating calcium diffusion across the muscle to the dose-response curve indicates that the exponential components of the tension transient curves are due to the properties of calcium diffusion through the extracellular space, and that the direction-dependent dynamics are caused by the nonlinearity of the dose-response curve.

Animals