[Comparison of low voltage amplitude electrochemotherapy with 1 Hz and 5 kHz frequency in volume reduction of mouse mammary tumor in Balb/c Mice]

Electrochemotherapy [ECT] is an efficient technique that high intensity electric pulses in combination with chemotherapeutic drugs are applied to tumor cells. The most important unpleasant sensation of electrochemotherapy is muscle contraction. To resolve this problem, there are two solutions: first, increasing the repetition frequency of electric pulses above the tetanic frequency; and, second, reducing the voltage amplitude. ECT using 1 Hz or 5 kHz frequency at high amplitude examined and no difference response of the tumor treatment was observed. But the role of frequency in low amplitude ECT not examined. Therefore, the present study compared the anti-tumor effectiveness of electrochemotherapyusing electric pulses with frequencies of 1 Hz and 5 kHz at 70 v/cm amplitude. ECT of spontaneous mouse mammary tumor [SMMT] transplanted in Balb/c was performed with intratumoral injection of bleomycine and applied four different electric pulse protocols: 1- a train of 8 pulses with duration 50 ms, 1 Hz frequency and 70 v/cm amplitude, 2- a train of 4000 pulses with duration 100 micros, 5k Hz frequency and 70 v/cm amplitude,3- a train of 8 pulses with duration 100 micro s, 1 Hz frequency and 1000 v/cm amplitude,4- a train of 8 pulses with duration 100 micros, 5 kHz frequency and 1000 v/cm amplitude. Our data demonstrate significant differences in tumor volumes between mice treated by 70 V/cm and 5 kHz frequency compared to1 Hz frequency but inhibited tumor growth in high amplitude with 1 Hz and 5 kHz is comparable. Based on these results, the pulses with 70 v/cm and 5 kHz frequency are most effective. On the basis of these results the frequency effect of electric pulses is important in low amplitude ECT.

Antitumor efficiency of electrochemotherapy by high and low frequencies and repetitive therapy in the treatment of invasive ductal carcinoma in Balb/c Mice

In electrochemotherapy [ECT], there is an unpleasant sensation of muscle contraction when using a low frequency [1 Hz]. Therefore, by increasing the pulse frequency above the tetanic frequency this painful sensation can be reduced. The aim of the present study is to compare the treatment efficiencies of low and high frequency ECT, and estimate the effect of its repeated sessions. We transplanted invasive ductal carcinoma into the flanks of female Balb/c mice. ECT was performed on the mice by the use of 8 pulses, 1000 v/cm, of 100 micro s duration at 1 Hz and 5 kHz repetition frequencies along with intra-tumoral injections of bleomycin. We also used this ECT protocol for the second therapy session six days after tumour regrowth. The effect of treatment was measured by calculating the tumor volumes for 24 days following treatment. Statistical analysis was performed with ANOVA. ECT at 1 Hz and 5 kHz pulse frequencies demonstrated significant inhibition of tumor growth, but after the first treatment the tumours began to regrow. Repetitive ECT sessions increased the curability of tumors up to 40% in the group treated by 1 Hz frequency and 60% in the group treated with 5 kHz frequency. Our results demonstrate that the effects of 1 Hz and 5 kHz pulse repetition frequencies are comparable for inhibited tumour growth. Repetitive treatment can improve the effectiveness of ECT

[EEG changes during exposure to extremely low frequency magnetic field on a small area of brain]

Effects of extremely low frequency magnetic fields [ELF-MF] with different intensities and frequencies has been investigated by several researchers. In most of these studies, the applied magnetic field has uniformly encountered whole brain and it has shown that changing intensity and frequency causes anomaly changes in electroencephalograms. The aim of current study was to investigate the effect of local exposure to ELF-MF with different intensities on EEG signals. Magnetic field with frequency of 10 Hz and intensity of 100, 120, 160, 200, 240, 280, 320 and 360 micro T was applied to F3 zone in 10-20 system of 3 men locally. Finally, relative power spectrum in 5 points of head in conventional frequency bands was assessed. An increase in alpha band in regions under exposure such as F3 and O1 in intensities of 100 and 360 micro T was observed. No changes in other bands such as theta band were found. It should be noted that none of the above effects was observed in closed-eye position. Regular effects due to increasing intensity of magnetic field was not observed and changing potential of EEG signals from magnetic field with intensity of 100 and 360 micro T is more than other intensities. Changing pattern of alpha band in F4, Cz, O2 and O1 was similar to exposed F3 zone and no resonance effect was observed at 10 Hz magnetic field