Measurement of electrical oscillations and mechanical vibrations of yeast cells membrane around 1 kHz.

Fröhlich postulated coherent polar oscillations as a fundamental biophysical property of biological systems. Recently, Pelling et al. (2004, 2005) detected mechanical vibrations of yeast cell membrane with atomic force microscope (AFM) and analyzed by Fourier analysis in the frequency range 0.5-2 kHz with amplitudes of the order of 1 nm. This article describes the measurement of electric activity of yeast cells in the acoustic frequency range and of mechanical vibrations of cell membrane. Spectrum analyzer and electrically and electromagnetically screened box with point sensor and amplifiers fed by batteries were used for measurement of synchronized and non synchronized tubulin mutants of yeast cells. We show that the electric activity of synchronized cells in the M phase is greater that of non synchronized cells. That corresponds to the findings of Pohl et al. (1981). Obtained results of measurement of cell electric activity are in good agreement with AFM findings.

Radioprotective effects of amifostine (WR-2721) or cystamine on radiation damage and its repair in rats whole body exposed to fission neutrons.

Sulphur containing radioprotective drugs amifostine (gammaphos, WR-2721) or cystamine (disulfide of meracaptoethylamine) of Czechoslovak production were examined in whole body fission neutrons irradiated rats in the thermal column of reactor VVR-S. Using the split-dose technic the first sublethal neutron dose in the range 1-2 Gy was followed by second lethal exposures in the two time intervals (3 or 6 days) using whole body fission neutrons irradiations (3 days interval) or whole body gamma-irradiations (6 days interval) for LD50/30 evaluation within next 30 days survival observation. In other experiments the mean survival time (MST) in days was estimated in different rats group, when animals were whole body fission neutrons irradiated twice with 3-days interval using the total lethal doses of 4 or 5 Gy. Protected rats received amifostine (160 mg.kg(-1) i.p. and 200 mg.kg(-1) i.m.) or cystamine (40 mg.kg(-1) i.p. and 50 mg.kg(-1) i.m.), control rats obtained saline 20 min before beginning of irradiation in the amount of 0.5 ml.100 g(-1) of the rat's body weight. Non-significant DRF value 1.13 for WR-2721 i.p. was calculated in survival studies in rats twice neutron irradiated with 3 days interval (DRF 1.04 for cystamine). Chemical protectors were administered before each neutron exposure. MST of twice neutron lethal iradiated rats was prolonged not regularly by radioprotectors tested. WR-2721 and cystamine i.m. were not able to increase 6 days reparation processes after sublethal 2 Gy fission neutrons whole body irradiated rats.