Mechanism of low-level microwave radiation effect on nervous system.

The aim of this study is to explain the mechanism of the effect of low-level modulated microwave radiation on brain bioelectrical oscillations. The proposed model of excitation by low-level microwave radiation bases on the influence of water polarization on hydrogen bonding forces between water molecules, caused by this the enhancement of diffusion and consequences on neurotransmitters transit time and neuron resting potential. Modulated microwave radiation causes periodic alteration of the neurophysiologic parameters and parametric excitation of brain bioelectric oscillations. The experiments to detect logical outcome of the mechanism on physiological level were carried out on 15 human volunteers. The 450-MHz microwave radiation modulated at 7, 40 and 1000 Hz frequencies was applied at the field power density of 0.16 mW/cm2. A relative change in the EEG power with and without radiation during 10 cycles was used as a quantitative measure. Experimental data demonstrated that modulated at 40 Hz microwave radiation enhanced EEG power in EEG alpha and beta frequency bands. No significant alterations were detected at 7 and 1000 Hz modulation frequencies. These results are in good agreement with the theory of parametric excitation of the brain bioelectric oscillations caused by the periodic alteration of neurophysiologic parameters and support the proposed mechanism. The proposed theoretical framework has been shown to predict the results of experimental study. The suggested mechanism, free of the restrictions related to field strength or time constant, is the first one providing explanation of low-level microwave radiation effects.

Microwave effect on diffusion: a possible mechanism for non-thermal effect.

In this study, we assume that microwave radiation affects hydrogen bonding between dipolar water molecules and through that diffusion in water at constant temperature. The experimental study was performed on the setup of two identical reservoirs filled with pure water and 0.9% NaCl solution and connected by a thin tube. Alterations of NaCl concentration in the reservoir initially filled with pure water were measured using the resistance of the solution as an indicator. The applied 450 MHz continuous-wave microwave field had the maximal specific absorption rate of 0.4 W/kg on the connecting tube. The standard deviation of water temperature in the setup was 0.02 °C during an experiment. Our experimental data demonstrated that microwave exposure makes faster the process of diffusion in water. The time required for reduction of initial resistance of the solution by 10% was 1.7 times shorter with microwave. This result is consistent with the proposed mechanism of low-level microwave effect: microwave radiation, rotating dipolar water molecules, causes high-frequency alterations of hydrogen bonds between water molecules, thereby affects its viscosity and makes faster diffusion.

Association between ventricular repolarization and main cardiovascular risk factors.

OBJECTIVE: To assess the association between QT interval, QT dispersion and main cardiovascular risk factors in Tallinn women population aged 50-69 years. DESIGN: A random sample of Tallinn population, 302 women underwent 12-lead rest ECG, echocardiography and laboratory tests. Corrected QT interval and QT dispersion were calculated. RESULTS: The significant correlation coefficients for corrected QT interval and dispersion were observed with systolic, diastolic, pulse pressure, blood pressure value grade, heart rate, left ventricular mass index, and total cardiovascular risk grade. According to the data of multiple logistic regression, risk factors independently associated with prolonged QTc and QTD were arterial hypertension: OR 2.69, p < 0.001 and OR 3.29, p < 0.001, pulse pressure ≥ 60 mm Hg: OR 2.62, p < 0.001 and OR 3.04, p < 0.001, age > 65 years: OR 2.44, p < 0.001 and OR 1.91, p < 0.01, family history of cardiovascular disease: OR 2.02, p < 0.01 and OR 2.48, p < 0.001, left ventricular hypertrophy: OR 2.78, p < 0.001 and OR 5.29, p < 0.001. Multivariable linear regression data showed an independent association between corrected QT interval, QT dispersion and systolic blood pressure: ß = 0.32, p < 0.001 and ß = 0.39, p=0.003, pulse pressure: ß = 0.21, p = 0.004 and ß = 0.27, p < 0.001, blood pressure value grade: ß = 0.35, p < 0.001 (for QT dispersion only), heart rate: ß = 0.21, p < 0.001 and ß = -0.19, p = 0.001, left ventricular mass index: ß = 0.23, p < 0.001 and ß = 0.27, p < 0.001. CONCLUSION: In Tallinn women population, electrocardiographic parameters reflecting ventricular repolarization are associated with systolic blood pressure, pulse pressure, blood pressure value grade, heart rate and left ventricular hypertrophy.

QT dispersion in relation to left ventricular geometry and hypertension in a population study.

OBJECTIVE: To study the relationship between QT interval dispersion, arterial hypertension and different left ventricular geometric patterns in the framework of a population study. DESIGN: A random sample of the population of Tallinn, 717 men and women aged 35-59, underwent standard 12-lead ECG at rest and echocardiography. Corrected QT dispersion was considered as prolonged when the duration was > or =70 ms. RESULTS: In hypertensives with concentric and eccentric hypertrophy, the mean values of corrected QT dispersion were significantly higher than in those with normal geometry. In the normotensive group no significant differences of the mean values of corrected QT dispersion were found in relation to left ventricular geometry. Mean values of corrected QT dispersion were higher in hypertensives than in normotensives in each left ventricular geometric pattern. Corrected QT dispersion > or =70 ms was mainly associated with concentric hypertrophy. CONCLUSION: Prolonged corrected QT dispersion is associated with left ventricular geometric abnormalities and arterial hypertension and is mostly related to concentric hypertrophy.

Arterial hypertension, left ventricular geometry and QT dispersion in a middle-aged Estonian female population.

The aim of the present study was to determine the prevalence of Left ventricular hypertrophy (LVH) and different left ventricular (LV) geometric patterns in the middle-aged women population of Tallinn, to assess the relationship between LV geometry, age, blood pressure and LV repolarization duration and inhomogeneity. A random sample of the population, 482 women aged 35-59, was examined in the framework of a cardiovascular risk factors survey for the WHO/CINDI programme years 1999-2000. Patients with valvular pathology, primary cardiomyopathy, atrial fibrillation, bundle branch blocks and flat T wave on electrocardiography (ECG) were excluded; 398 (82.2%) of the participants underwent echocardiography (Echo) and standard 12-lead ECG at rest and were included in the study. LVH was defined if left ventricular mass (LVM), LVM/height and LVM/BSA were >198 g, >121 g/m and > 120 g/m2, respectively. Arterial hypertension was determined in 23.1% of the women. The prevalence of arterial hypertension was three times higher in those aged 50-59 than in those aged 40-49 (37.4% vs 13.2%; p < 0.05). Different geometric patterns were found as follows: concentric hypertrophy in 9.1%; eccentric hypertrophy 33.9%; concentric remodelling 9.5% and normal geometry 47.5% of the participants. Concentric hypertrophy was found exclusively in hypertensive women and increased with age. No age-related eccentric hypertrophy and concentric remodelling differences were found, either in the normotensive or in the hypertensive group. Prolonged QT dispersion--a marker of increased myocardial electrical instability, was associated with LVH and arterial hypertension and was related mostly to concentric hypertrophy in hypertensives.