Lóránd Kellényi

Short GSM mobile phone exposure does not alter human auditory brainstem response

BackgroundThere are about 1.6 billion GSM cellular phones in use throughout the world today. Numerous papers have reported various biological effects in humans exposed to electromagnetic fields emitted by mobile phones. The aim of the present study was to advance our understanding of potential adverse effects of the GSM mobile phones on the human hearing system.MethodsAuditory Brainstem Response (ABR) was recorded with three non-polarizing Ag-AgCl scalp electrodes in thirty young and healthy volunteers (age 18–26 years) with normal hearing. ABR data were collected before, and immediately after a 10 minute exposure to 900 MHz pulsed electromagnetic field (EMF) emitted by a commercial Nokia 6310 mobile phone. Fifteen subjects were exposed to genuine EMF and fifteen to sham EMF in a double blind and counterbalanced order. Possible effects of irradiation was analyzed by comparing the latency of ABR waves I, III and V before and after genuine/sham EMF exposure.ResultsPaired sample t-test was conducted for statistical analysis. Results revealed no significant differences in the latency of ABR waves I, III and V before and after 10 minutes of genuine/sham EMF exposure.ConclusionThe present results suggest that, in our experimental conditions, a single 10 minute exposure of 900 MHz EMF emitted by a commercial mobile phone does not produce measurable immediate effects in the latency of auditory brainstem waves I, III and V.

The corner frequencies of the ECG amplifier for heart rate variability analysis

Heart rate variability (HRV) analysis is considered a popular method both in clinical and research fields. However, several ignored technical artifacts may falsify its measurements. The current study investigates the effects of corner frequencies of the ECG amplifier on the precision of RR-interval detection. Clear or noise-corrupted ECG records with predefined parameters consisting of 21 cycles were generated, played back through analog filters and data-logged on a Pentium-based computer with a DaqBoard2000 data acquisition card. 0.1-10 Hz second-order high pass and 20-100 Hz fourth-order low pass Bessel and Butterworth filters were used. The RR-intervals were measured between seven reference points of the ventricular complexes before and after filtering. High and low pass at every frequency cutoff and with both filter types results in correct RR-intervals within 1 ms error. However, a lower cutoff below 1 Hz is needed to maintain ECG morphology. AC interference or Gaussian random noise can falsify the measured RR-intervals up to 16 or 34 ms, respectively. These errors may be reduced to 1-4 ms with appropriate low pass filters. A frequency range of 0.5-20 Hz for the ECG amplifier can be sufficient for HRV analysis reducing the errors from AC interference or random noise.

Selective induction of ultrastructural (neurofilament) compaction in axons by means of a new head-injury apparatus.

A new weight-drop head-injury apparatus is described that can produce a momentary depression of predetermined depth at a predetermined site of the elastic calvaria of scalped young adult rats. In Wistar rats weighing about 200 g, a 0.75-mm deep calvaria depression immediately caused ultrastructural (neurofilament) compaction in many long axon segments, which were diffusely scattered among non-compacted axons in a well-defined area of cortical layers IV and V under the impact site. Apart from these morphological changes and swollen astrocytic processes in their vicinity, the brain tissue appeared non-impaired. The blood pressure, intracranial pressure, heart rate and respiration rate had returned to the normal range in 1 min. Diffuse axonal swelling caused by impaired axonal transport, ultrastructural compaction in neuronal soma-dendrite domains, impression fracture and subarachnoid or subdural hemorrhages were observed only in rats with a calvaria depression of 1mm or more. All these features create favorable circumstances for study of various problems that are closely related to the ultrastructural (neurofilament) compaction in axons, such as the fate of the affected axons.

Noninvasive Recording of True-to-Form Fetal ECG during the Third Trimester of Pregnancy

Objective. The aim of the study was to develop a complex electrophysiological measurement system (hardware and software) which uses the methods of electrophysiology and provides significant information about the intrauterine status of the fetus, intending to obtain true-to-form, morphologically evaluated fetal ECG from transabdominal maternal lead. Results. The present method contains many novel ideas that allow creating true-to-form noninvasive fetal ECG in the third trimester of the pregnancy in 80% of the cases. Such ideas are the telemetric data collection, the “cleanse” of the real time recording from the maternal ECG, and the use of the cardiotocograph (CTG) that allows identifying the fetal heart events. The advantage of this developed system is that it does not require any qualified staff, because both the extraction of the information from the abdominal recording and the processing of the data are automatic. Discussion. Although the idea of a noninvasive fetal electrocardiography is more than 100 years old still there is no simple, effective, and cheap method available that would enable an extensive use. This developed system can be used in the third trimester of the pregnancy efficiently. It can produce true-to-form fetal ECGs with amplitude less than 10 µV.

The short-term effect of smoking on fetal ECG

Abstract Background: The number of women who smoke during pregnancy is significant even today. The harmful effects of smoking during pregnancy are well known but there are no data on the effects of smoking on fetal electrocardiography (ECG). The lack of data is in connection with the difficulties of recording fetal ECG through the maternal abdomen. Method: Third trimester pregnant women who were not able to give up the harmful passion of smoking despite repeated attempts of persuasion were recruited in the study on voluntary basis. The fetal ECG was recorded non-invasively through the maternal abdomen before, during and after smoking, then the data were processed offline. The electrophysiological measurements were performed by a self developed ECG device, which allowed the examination of the morphological differences in “true-to-form” fetal ECG in addition to studying the variability of fetal heart rate. The study involved nine pregnant women. The observed changes are presented through case studies of those pregnant women who showed the most significant anomalies. Results: Compared with the resting state fetal heart rate was increased during smoking. The short-term variability of fetal heart rate was narrowed, while the mother’s heart rate did not change significantly – which was an indication of direct fetal stress. No explicit ischemic signs were detected in fetal ECG during smoking, however, in the increasing period of the fetal heart rate, the T wave morphology changed slightly, then it returned to normal. Conclusions: Demonstrable by the electrophysiological methods, smoking has a direct effect on fetal cardiac function. The fetal heart rate variability shows a pattern during smoking which is a typical sign of stress conditions among adults. The results may have educational consequences as well. Understanding those, hopefully will help pregnant women give up this harmful addiction.

The assessment of neural injury following open heart surgery by physiological tremor analysis.

Introduction The appearance of post-operative cognitive dysfunction as a result of open heart surgery has been proven by several studies. Focal and/or sporadic neuron damage emerging in the central nervous system may not only appear as cognitive dysfunction, but might strongly influence features of physiological tremor. Material and methods We investigated 110 patients (age: 34-73 years; 76 male, 34 female; 51 coronary artery bypass grafting (CABG), 25 valve replacement, 25 combined open heart surgery, 9 off-pump CABG) before surgery and after open-heart surgery on the 3rd to 5th post-operative day. The assessment of the physiological tremor analysis was performed with our newly developed equipment based on the Analog Devices ADXL 320 JPC integrated accelerometer chip. Recordings were stored on a PC and spectral analysis was performed by fast Fourier transformation (FFT). We compared power integrals in the 1-4 Hz, 4-8 Hz and 8-12 Hz frequency ranges and these were statistically assessed by the Wilcoxon rank correlation test. Results We found significant changes in the power spectrum of physiological tremor. The spectrum in the 8-12 Hz range (neuronal oscillation) decreased and a shift was recognised to the lower spectrum (p < 0.01). The magnitude of the shift was not significantly higher for females than for males (p < 0.157). We found no significant difference between the shift and the cross-clamp or perfusion time (p < 0.6450). Conclusions The assessment of physiological tremor by means of our novel, feasible method may provide a deeper insight into the mechanism of central nervous system damage associated with open heart surgery.