| At present,tumor has been one of the dominating murderers of health of human being. The current modalities of cancer treatment include surgery,chemotherapy,radiation therapy,immunotherapy, and their combinations. Now a new biological therapy——the therapy using electric pulse,because of its high efficiency in restraining tumor,being easy in parameter controlling and no remnants toxicity, has gotten considerable interest of many specialists and scholars, and quite great progress in only more than 20 years. It is proved that the steep pulsed electric fields can kill the tumor cell and damaged the tumor in vivo and vitro. In our studies wu use the tumor models in vivo treated by SP in order to discuss the bioeffects of steep pulse,the feasibility,the efficacy and the optimal dosage of steep pulse for treatment of rabbit VX2 liver tumor. PART 1 THE AIM OF THIS PART IS TO OBSERVE THE BIOEFFECTS OF STEEP PULSED ELECTRIC FIELDS ON LIVER OF RABBITS IN VIVOObjective To investigate the role of heat-effect in pulsed electric field through disscuss the temperature increase . To study the Pathological change of tissue damage in cancer tissue induced by Steep Pulse.Material and methods Thirty rabbits bearing VX2 liver tumor were selected to be classify two groups randomly. Every rabbit was exposed to steep pulse electric field with serial voltage dependently, The temperature of the injuring tissues was measured. histological examination were used to observe the injuring effect, and ultrastructural changes were detected.Results The temperature of the injuring tissues was measured . Before the treat,the temperature was 34 . 8±2.07℃average,and after , the temperature was 35.93±2.19℃average,no significant rise was detected(P>0.05).The histomorphological changes were examined and compared between experimental and control group.After treatment, pyknosis, karyoclasis and karyolysis of tumor cells were observed light and electron mircroscope.Serious changes appeared more time later.Conclusion Heat-effect didn't play important rloe in SP therapy. Steep pulsed electric fields can kill the tumor cell and damaged the tumor. PART 2 DOSIMETRY AND THE OPTIMAL DOSAGE OF STEEP PULSE FOR TREATMENT OF RABBIT VX2 LIVER TUMORObjective To investigate the dosimetry and the optimal dosage of steep pulse for treatment of rabbit VX2 liver tumor.Material and methods Rabbits with VX2 liver tumor were divided into four treatment groups (500V/10μs/20Hz, 600V/10μs/20Hz, 700V/10μs/20Hz,800V/10μs/20Hz)and control group . Changes in the tumors volume were observed 3 days after the treatment.Comparison was made between the four treatment groups and control group,and within the treatment groups.Results Tumour tissues exposed to electrical pulse field were observed to be coagulation necrosis by TTC. It was shown as dose- dependence between the dosage of the steep pulse and the tumors necrosis volume,necrosis area increased gradually with the increasing of the electric -field intensity.When the tumor tissue was exposed to electrical pulsed fields of 700 V voltage which was fixed pulse width of 10μs, the frequency of 20 Hz and the time of 10 min,the tumor tissue appeared the necrosis obviously and the liver necrosis area didn't obviously.The dose in group 700 voltage may be considered as the optimal dosage for the treatment of rabbit liver VX2 tumor. Conclusion It was shown as dose-dependence between the dosage of the steep pulse and the tumors necrosis volume. The dose in group 700 voltage ,which was fixed pulse width of 10μs, the frequency of 20 Hz and the time of 10 min,may be considered as the optimal dosage for the treatment of rabbit liver VX2 tumor. |
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