الفهرس 
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Abstract
Cancer is one of the most serious challenges of this time. It is not only can lead to the patient death but also it can make the patient and his family suffer physiologically and pschycologically.
There are many ways for cancer treatment such as surgery, chemotherapy, radiotherapy and hormontherapy. Chemothaerapy is the most widely used treatment for cancer.
Cancerous cells are so weak and can be killed easily if the cytotoxic drug enters inside the cell, but the problem of chemotherapy is all the cytotoxic drugs are hyDROPhilic (water-soluble) and the tumor cell membrane consists from lipid bilayer, so the cytotoxic drug can’t penetrate the tumor cell membrane barrier.
Oncologists give chemotherapy systemically ( injected to circulate with the blood) to allow cytotoxic drug to reach to the tumor cells with the blood, but this way kill the normal cells of the patient as well as the tumor cells which cause serious side effects. The side effects of the chemotherapy can cause toxicity in the blood in some cases and sometimes the doctors have to stop the treatment to keep the patient life.
So, if the cytotoxic drug can be given intra-tumoral, no side effects will happen. To make that; the cell membrane barrier should be overcome. Many researches tried to find a way to give chemotherapy intra-tumoral, they found that any molecule should send an electrical pulse to the cell membrane of the tumor, and if the tumor recognizes this molecule as safe material then the pores of the cell membrane are opened for this molecule.
In this work; electrical unbalance for the cell membrane was done during the time of injection of the cytotoxic drug intra-tumoral, to prevent the tumor from the good recognition of the injected molecules. This unbalance was made by using electric fields. It was agreed between the researchers that the combination of electric field with chemotherapy can be named as electrochemotherapy.
In this study; Ehrlich tumor was used as the tumor model because it is solid tumor, subcutaneous, so it can be measured and noticed easily, as well as the application of the electric field to it is easy. Bleomycin was used as cytotoxic drug model because it has strong effect of the cells DNA and can break it in few seconds when it enters the cell.
The aim of this work was to study the effect of two different electric fields (pulsed sine waves and direct current) combined with bleomycin on Ehrlich tumor, as well as the optimization of all the electrical parameters that lead to the best response for the treatment protocol.
In order to make this; two circuits were home made; one to produce pulsed sine waves, and the other to produce DC currents. Both circuits’ electrical outcomes were examined using oscilloscope.
The delivering of these electrical fields was done by using stainless steel needle electrodes. Because of the importance of the electrical field distribution to cover the whole tumor tissue in homogenous way, three electrodes configurations were home made to select the configuration that gives electrical field homogeneity. These configurations were: two simple electrodes (one anode and one cathode), four electrodes (three anodes in a form of equal sided triangle and one cathode at the center of the triangle), six electrodes (five anodes in a form the circumference of a circle and one cathode at the center of the circle).
In order to select the optimum electrode configuration, theoretical and practical examination for each configuration was done.
The theoretical calculation was took place by two ways: the first was the analytical analysis of each electrode configuration using equations derivative of Laplace equation, the second way was the numerical analysis for each configuration using JAVA software analysis.
The practical measurements were performed for each electrode configuration in a home made tissue phantom with electrical characters similar to the biological tissues.
To optimize the potential difference of the pulsed sine waves that should be given with bleomycin; a pilot study was done using different potential differences (3.6, 7.1, 12.5, 17.9, 26.8, 35.7, and 71.1 V/cm) on seven mice-bearing groups, each of 5 mice, to select the voltage that give the best tumor cure response with minimum side effects.
To optimize the DC current that should be given with bleomycin, another pilot study was performed using different current intensities (0.15, 1.6, 3.2 and 5.13 mA/cm2) on four mice-bearing tumor, each of five mice, to select the optimum current that give the best tumor prognosis with minimum side effects.
In both pilot studies, one group injected with bleomycin only, and one group injected with saline only served as controls.
The resistance of the tumor was measured using LCR meter (high internal impedance device) at the surface (≈0.25mm from the surface) and at the depth of the tumor (at 5mm inside the tumor).
After all the parameters were optimized the treatment protocol was applied that: six mice-bearing tumors each of 30 mice were classified as; GІ exposed to pulsed sine waves (PEF) combined with bleomycin, GІІ exposed to PEF waves only, GІІІ exposed to DC current combined with bleomycin, GІV exposed to DC currents only, GV exposed to bleomycin only and G0 injected with saline only and served as control.
5 mice from each group were sacrificed in time intervals: just before the treatment, two, nine and eighteen days after the treatment, and tumor size, tumor weight, spleen weight to total body weight, DNA fragmentation, as well as histological and ultrastructural examinations were performed.
The results of this work revealed that; six electrodes configuration gives the best electrical field distribution homogeneity. The data of analytical, numerical and the practical measurements agreed together in that. So six electrodes configuration was used in the treatment protocol.
The pilot studies data stated that the optimum potential difference of the pulsed sine waves that should be applied is 3.6 V/cm, and the best current intensity for DC is 0.15 mA /cm2). So the treatment protocol was done using these optimum conditions.
The data of the tumor resistance indicate that the resistance of the tumor surface highly increases as the tumor size increases, on contrast the resistance of the tumor internal part decreases as the tumor size increases. So, it is better to use needle electrodes to deliver the electricity in the lower resistance part of the tumor.
The treatment protocol results reveled that the using of DC currents combined with bleomycin gives very good prognosis to the tumor and complete disappearance of the tumor in some mice of this group, the average tumor size, weight are highly decreased at the end of the experiment as well as the high percent of the fragmented DNA stating that there was high damage in the tumor tissue, and the spleen weight started to regain its normal weight revealing that the immune system stimulation return to the basal state and no need to high immunity stimulation.
All these data are confirmed with histology and ultrastructural micrographs that show high damage in the tumor tissue and complete disappearance of the tumor in some mice .The survival time of this group was high and 40% from them stay alive and in good health to the end of the four months follow up, without any tumor growth
This new combination between DC and bleomycin gives many folds better results than the old ways of treatment either by using bleomycin only or DC only. Although the groups exposed to DC currents only or that exposed to pulsed sine waves showed good prognosis at the first days after the treatment, the tumor started to grow again at the end of the experiment.
These results can be explained as; DC currents cause high electrochemical reactions that lead to high unbalance in the cell membrane during the time of exposure so the bleomycin can enter into the cells and kill them, and after the end of the exposure the formed free radicals complete the tumor destruction and prevent its growth again.
During pulsed sine waves exposure, the bleomycin enters into the cells probably by induced-endocytosis and kill them, but the effect doesn’t expand after the exposure so many doses should be applied.
Using of DC only takes the advantages of the electrochemical reaction only, so it is so limited to the time of the exposure.
from these results, a conclusion can be stated that the using of DC currents with bleomycin can be an optimum way for tumor treatment specially in the solid tumors, and because the treatment can be only one dose, the patient will not suffer from this technique. On the other hand the using of DC only or pulsed sine waves combined with bleomycin may need many doses at different time intervals to ensure the complete death of the tumor.