In vivo electroporation of skeletal muscle: threshold, efficacy and relation to electric field distribution.

In vivo electroporation is increasingly being used to deliver small molecules as well as DNA to tissues. The aim of this study was to quantitatively investigate in vivo electroporation of skeletal muscle, and to determine the threshold for permeabilization. We designed a quantitative method to study in vivo electroporation, by measuring uptake of (51)Cr-EDTA. As electrode configuration influences electric field (E-field) distribution, we developed a method to calculate this. Electroporation of mouse muscle tissue was investigated using either external plate electrodes or internal needle electrodes placed 4 mm apart, and eight pulses of 99 micros duration at a frequency of 1 Hz. The applied voltage to electrode distance ratio was varied from 0 to 2.0 kV/cm. We found that: (1) the threshold for permeabilization of skeletal muscle tissue using short duration pulses was at an applied voltage to electrode distance ratio of 0.53 kV/cm (+/-0.03 kV/cm), corresponding to an E-field of 0.45 kV/cm; (2) there were two phases in the uptake of (51)Cr-EDTA, the first indicating increasing permeabilization and the second indicating beginning irreversible membrane damage; and (3) the calculated E-field distribution was more homogeneous for plate than for needle electrodes, which was reflected in the experimental results.

[Scalding injuries in children]. / Skoldingsskader hos barn.

During the years 1989-91, 88 children were hospitalized in the Burn Unit. 60 children, of whom 57 were under five years of age, suffered from scalds. All of the injuries happened at home and nearly 60% of the children received immediate treatment with cold water. The causes of the scalds were hot tap water, tea, coffee or boiling water. Half of the children did not need surgery and stayed in the unit from one to 61 days. Information on burns and scalds prevention and first aid must be given to parents at the Health Care Centres, on radio and TV, and in the newspapers. In order to reduce scalds from hot tap water, legislation should be considered which would limit the temperature of such water to maximum 60 degrees C. Health personnel who meet these problems should present the above information to the politicians.