Stereological analysis of thyroid mast cells in rats after exposure to extremely low frequency electromagnetic field and the following "off" field period.

Influence of extremely low frequency electromagnetic field (ELF-EMF) on thyroid gland mast cells was investigated on male Mill Hill rats. Animals were exposed to EMF (50 Hz, 50 microT to 500 microT, 10 V/m) from 24 hours after birth, 7 hours/day, 5 days/week for three months when a part of animals (group I) was sacrificed, while the rest of them were subjected to recovery evaluation and sacrificed after one (group II), two (group II) and three (group IV) weeks following the exposure. Stereological analysis on toluidine blue-stained paraffin sections showed increased volume density of degranulated mast cells in all groups and, except in group III, and numerical density as well, implicating the sensitivity of thyroidal mast cells to power frequency EMFs. Since in our previous investigations, morphofunctional alterations of thyroid gland in rats exposed to ELF-EMF were found the contribution of released mast cell mediators to these changes could be presumed.

Evaluation of rat thyroid gland morphophysiological status after three months exposure to 50 Hz electromagnetic field.

Objective of our study was to use morphophysiological criteria in order to determine the sensitivity of male rat thyroid gland to an extremely low frequency electromagnetic field (ELF-EMF) influence and the ability of the gland to repair after period of exposure. Animals were exposed to 50Hz, 50-500 microT ELF-EMF for 3 months when a part of them (group I) were sacrificed, while the rest of animals were subjected to recovery evaluation of the gland and sacrificed after 1 (group II), 2 (group III) and 3 (group IV) weeks. Histological and stereological analyses were performed on paraffin and semifine thyroid gland sections. Serum T3 and T4 were also determined. Histological and stereological analyses showed that the volume density of follicular epithelium and thyroid activation index decreased, while the volume density of colloid and capillary network increased in group I, II and III. The values of all these parameters in group IV were similar to corresponding controls. Serum T3 and T4 concentrations were significantly lower in all exposed animals, except in group I. Results of this study demonstrate that after significant morphophysiological changes caused by ELF-EMF exposure thyroid gland recovered morphologically, but not physiologically, during the investigated repair period.

Morphophysiological status of rat thyroid gland after subchronic exposure to low frequency electromagnetic field.

The objective of this study was to examine the impact of low-frequency electromagnetic field on male rat thyroid gland of Mill Hill strain. Animals were exposed to 50 Hz frequency, of decaying intensity from 500 microT to 50 microT and 10 V/m field, beginning 24 hours after birth, 7 hours a day, 5 days a week during three months. Results of histological and stereological analysis showed increased volume density of thyroid follicles, decreased thickness of the follicular epithelium, intrafollicular colloid content in lumen, decreased thyroid activation index, increased volume density of parafollicular cells, decreased volume of interfollicular connective tissue and increased number of degranulated mast cells in exposed animals in regard to control animals. Radioimmunologic assays were used to examine thyroid hormone concentrations in the blood serum revealing decrease of the total T4 as well as of total T3 in animals exposed to electromagnetic field in regard to controls. The obtained results show that a three month-exposition of animals to low frequency electromagnetic field led to morphofunctional alterations of the thyroid gland that can be referred to as reduced activity of the gland.

[100 years since the birth of Academician Petr Kuzmic Anohin]. / Sto godina od rodenja akademika Petra Kuzmica Anohina.

This paper provides a brief biography of an outstanding physiologist and academician Petr Kuzmich Anokhin. With his functional system theory, academician P. K. Anokhin was the first to introduce a systematic approach to discussing functioning of an organism. Principles of functional systems have been applied in technical systems as well.

[Magnetography--a potential diagnostic method in the 21st century]. / Magnetografija--potencijalna dijagnosticka metoda 21. veka.

Electric currents in human body are generated by variations in membrane and action potentials. These bioelectric currents cause magnetic field which could be detected both inside and outside human body, on a certain distance. Measurements of biomagnetic fields are still at an experimental stage, but soon, with improvements in technology, they will become very important diagnostic tools, like registrations of surface electric potentials already are. Registration of magnetogram is performed without a direct contact of the probe and the surface, which enables measurements on the top of clothes, bandages and casts. Magnetic field probe can be easily moved from one part of the body to another, enabling so tracing of the observed signal. Similar mobility is not possible in electrography.

[Mechanisms of epileptogenesis and antiepileptic drugs]. / Mehanizmi epileptogeneze i antiepilepticki lekovi.

Contemporary data about the mechanisms of epileptogenesis are reviewed. The role of the neuronal membrane and synapsis in the neurons changed by epilepsy is particularly pointed out. The concept of "the paroxysmal depolarizational shift" is defined. Role of some neurotransmitters in the mechanisms of epileptogenesis and their classifications into excitatory and inhibitory ones are also presented. It is pointed to a great variety of receptors for neurotransmitters as well as the role of calcium ions in mechanisms of epileptogenesis. A review of "classical" and new antiepileptic drugs is created and possible mechanisms of their effect are stated. The same antiepileptic medicaments are listed in a special table depending on the type of epilepsy in which they have effect. It is certain that during the last two decades electrophysiologic, biochemic and pharmacologic researchers have significantly improved the knowledge of the main occurrences responsible for epileptogenesis. However, a lot of facts are still doubtful.

[The effect of low-frequency electromagnetic fields on the neuroendocrine system]. / Uticaj niskofrekventnih elektromagnetskih polja na neuroendokrini sistem.

This paper presents literature data about effects of low-intensity variable electromagnetic fields on the neuroendocrine system of experimental animals. We mostly paid attention to electromagnetic fields frequently found in our environment, in technological processes, even in our everyday life. This study shows that the regulatory systems (nervous and endocrine) are extremely sensitive to effects of electromagnetic fields. In regard to structures of the central nervous system hypothalamus shows particularly high sensitivity whereas we can consider a hypothesis that effects of this physical factor may be expected in other systems too. It has been emphasized that the effects of electromagnetic fields on regulatory mechanisms may be connected with primary disturbances on the cellular and subcellular (mitochondrial) level.

The influence of low intensity 50 Hz electromagnetic field exposure on blood Na, K and Cl concentrations in humans.

In this work we investigated the long term exposure effects (average 9 years, 7 hours a day, 5 days a week) to a 50 Hz low level (1-30 microT electromagnetic field. The concentrations of sodium (Na), potassium (K) and chlorine (Cl) in blood plasma and erythrocytes of female factory workers were monitored as quantitative parameters.

[Participation of brain-specific S-100-group proteins in the neurophysiological mechanisms of habituation]. / Uchastie mozgospetsificheskikh belkov gruppy S-100 v neirofiziologicheskikh mekhanizmakh privykaniia.

The possible role of S-100 brain specific proteins and their participation in the neuronal mechanisms of habituation were studied on identified neurons of the snail Helix pomatia. Extracellular application and intracellular injection of antibodies to S-100 proteins caused a rapid and significant decrease of neuronal responses to repeated stimulation in comparison with the control. During the action of antibodies a significant decrease of the evoked EPSP amplitude, increase of the action prepotential latency and a decrease in discharge frequency were observed. At the same time the membrane potential, membrane input impedance, pacemaker potentials did not change. The obtained effect is supposed to be caused by interruption of the synaptic transmission. Possible involvement of S-100 protein in the functioning of synaptic structures as one of the integrating apparatus of the neuron is discussed.