Mathematical description of combined action of ultrasound and hyperthermia on yeast cells.

The inactivation of diploid yeast cells of Saccharomyces cerevisiae was studied after simultaneous treatment of ultrasound and hyperthermia. The existence of a definite temperature range was proved within which a synergistic interaction was determined. An optimal temperature that maximized the synergy could be identified. A simple mathematical model of synergistic interaction of damages produced by ultrasound and high temperature has been proposed. The model suggests that synergism is expected from the additional lethal damage arising from the interaction of sub-lesions induced by both agents. The model allows quantitative analysis of the combined action of two agents used to be performed, and predicts the greatest value of the synergistic effect and conditions under which it can be achieved.

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