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The combination of chemotherapy drugs and high electric field treatment in local cancer is named electrochemotherapy. The European Standard Operation Procedure of Electrochemotherapy (ESOPE) provides guidelines for treatment of cutaneous and subcutaneous tumors. The electrochemotherapy of numerous tumors varying in sizes is more convenient using needle electrodes. However, ESOPE recommends that needle electrodes are applied to deeper tumors. The application of needle electrodes to treatment of superficial small tumors seems to be practical in electrochemotherapy. Plate electrodes and gel improve the electrochemotherapy efficacy. This technique provides electric field homogeneity in irregularly shaped tissue structures (bulk tumors). We propose an investigation of needle electrode and gel in electrochemotherapy of superficial tumors. In vivo experiment with squamous cell carcinoma (SCC) spontaneous nodules in dog was used to validate the mathematical tissue model. The numerical model considers the tissue conductivity dependent on local electric field. Our studies demonstrated that conductive gel is important for effective treatment of superficial tumors with needle electrodes. The needle electrodes and gel presented reduction of medium current, increased the tumor-free margin, and improved the practical application in relation to plate electrode., (Copyright © 2015 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

Electrochemotherapy is a combination of high electric field and anticancer drugs. The treatment basis is electroporation or electropermeabilization of the cell membrane. Electroporation is a threshold phenomenon and, for efficient treatment, an adequate local distribution of electric field within the treated tissue is important. When this local electric field is not enough, there is a regrown tumor cell; however, if it is stronger than necessary, permanent damage to the tissue occurs. In the treatment of dogs, electrochemotherapy is not yet an established treatment for mast cell tumor in veterinary medicine, although there are studies showing evidence of its effectiveness. In this study, we examined electrochemotherapy of dog mast cell tumor with numerical simulation of local electric field distribution. The experimental result was used to validate the numerical models. The effect of tumor position and tissue thickness (tumor in different parts of dog body) was investigated using plate electrodes. Our results demonstrated that the electrochemotherapy is efficient and flexible, and even when the tumor extends into the subcutis, the treatment with plate electrode eliminated the tumor cells. This result suggests that electrochemotherapy is a suitable method to treat mast cell tumors in dog., (Copyright © 2014 International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.)

Conductivity measurements in suspensions of biological cells have been used since many years for electroporation effectiveness evaluation. However, conductivity modeling by means of instantaneous values of current and voltage during pulse application does not take into account the effects of the sample reactance and the dielectric dispersion of the medium. This can lead to misinterpretation in the electroporation analysis. The electrical modeling and characterization of electroporation using sinusoidal signal analysis at 10 kHz proposed in this paper allows us to avoid distortions due to reactive effects of the sample. A simple equation establishes the relation between suspension conductivity and membrane conductance. This model was used in experiments with suspensions of yeast cells and applied electric fields of up to 450 kV/m for 1 ms. The analysis using the proposed model resulted in membrane conductance values of up to 8000 S/m (2) and allowed estimating the distribution profile of conductance on the cell membrane.

There are several models of decomposition of the electrocardiogram (ECG). Some of these models are intended to describe the ECG signal, and others are more specific to extract the relevant information relating to individual waveform which contributes to explain the P-QRS complex. The latter approach may be particularly suitable for a portion where a morphological analysis of the ECG is of particular interest, as the cardiac repolarization segment or T-wave. This study aims: to model and detect useful patterns in the evaluation of T wave morphology, which explains the different changes in ventricular repolarization during inhalation of Salbutamol.

An intense electric field can be applied to increase the membrane conductance G(m) and consequently, the conductivity of cell suspension. This phenomenon is called electroporation. This mechanism is used in a wide range of medical applications, genetic engineering, and therapies. Conductivity measurements of cell suspensions were carried out during application of electric fields from 40 to 165 kV/m. Experimental results were analyzed with two electroporation models: the asymptotic electroporation model was used to estimate G(m) at the beginning and at the end of electric field pulse, and the extended Kinosita electroporation model to increase G(m) linearly in time. The maximum G(m) was 1-7 × 10(4) S/m(2), and the critical angle (when the G(m) is insignificant) was 50°-65°. In addition, the sensitivity of electroporated membrane conductance to extracellular and cytoplasmatic conductivity and cell radius has been studied. This study showed that external conductivity and cell radius are important parameters affecting the pore-opening phenomenon. However, if the cell radius is larger than 7 μm in low conductivity medium, the cell dimensions are not so important.

The application of electric pulses in cells increases membrane permeability. This phenomenon is called electroporation. Current electroporation models do not explain all experimental findings: part of this problem is due to the limitations of numerical methods. The Equivalent Circuit Method (ECM) was developed in an attempt to solve electromagnetic problems in inhomogeneous and anisotropic media. ECM is based on modeling of the electrical transport properties of the medium by lumped circuit elements as capacitance, conductance, and current sources, representing the displacement, drift, and diffusion current, respectively. The purpose of the present study was to implement a 2-D cell Model Development Environment (MDE) of ionic transport process, local anisotropy around cell membranes, biological interfaces, and the dispersive behaviour of tissues. We present simulations of a single cell, skeletal muscle, and polygonal cell arrangement. Simulation of polygonal form indicates that the potential distribution depends on the geometrical form of cell. The results demonstrate the importance of the potential distributions in biological cells to provide strong evidences for the understanding of electroporation.

The spatial distribution of electrical potential and current in a suspension of spherical cells under an applied electric field was numerically obtained using the equivalent circuit method (ECM). The effect of the proximity of the cells was studied in a set of simulations where the volumetric fraction varied from 0.24 to 0.66. The results show that the transmembrane potential for cells in the suspension is lower than the theoretically predicted value for a single dielectric membrane under a uniform electric field. It was also observed that as the volumetric fraction is increased, the transmembrane potential on the pole of the cells decreases linearly. Furthermore, the conductivity of the suspension was also observed to be a function of the volumetric fraction and this result is in a good agreement with the Maxwell's model for spherical particles suspended in a volume conductor.

This article presents a numerical study of the electroporation process of spherical cells suspended in an electrolyte solution, using the equivalent circuit method (ECM) for field calculation proposed by Ramos et al. A model for the electric conductance of the cell membrane derived from the analytical and experimental results obtained by Glaser et al. for planar lipidic membranes was applied. The influence of the cell concentration and membrane properties (described in the model) on the membrane current, membrane potential, and dependence of the electrolyte conductivity on the applied electric field was studied. These results clarify the electric events connected with the pore opening process and allow the planning of experimental approaches to study reversible membrane rupture in real cells.