[Interleukin-6 acts in different ways via soluble and membrane-bound receptors]

Interleukin-6 is a multifunctional cytokine participating in the regulation of several immunologic and other cell-physiological phenomena. It acts via a receptor consisting of two components, that besides the ligand-specific chain also contains a second component of 130 kD (gp 130). The soluble form of the ligand-specific component of this receptor was shown to occur physiologically in body fluids and -following the binding of interleukin-6-to be capable of associating with the membrane-bound receptor component and inducing signal-transduction. We studied the possible differences between the effects of interleukin-6 exerted via membrane-bound or soluble receptors on HepG2 human hepatoma and primary rat hepatocyte cultures. We used two methods to study the action of interleukin-6: the mRNA expression of the protooncogene junB as an early marker, and the protein production of fibrinogen as a late one. The effect of interleukin-6 on both cell types examined with both methods used was lower via the soluble than the membrane-bound receptor. In addition, the soluble receptors alone (without interleukin-6) could induce the expression of the junB gene. Considering the wide-spread biological and pathological activities of interleukin-6 these phenomena could have some role in the pathogenesis of some diseases.

Development of competitive mRNA PCR for the quantification of interleukin-6-responsive junB oncogene expression

The transcription factor junB belongs to the jun family of protooncogenes. The appearance of junB mRNA in hepatic cells is an extremely early and sensitive marker of the action of proinflammatory cytokines including interleukin-6. In this study, a competitive reverse transcription (RT)-PCR assay has been developed that is suitable for the quantitative determination of junB mRNA expression. This nonisotopic assay compared to other methods (e.g., Northern blot) is a fast and convenient way to determine the expression of the junB gene and thus the immediate concentration- and time-dependent action of interleukin-6. Because interleukin-6 and interleukin-6-type cytokines play a highly important regulatory role in various pathophysiologically important processes, such as hepatic acute-phase reaction, the quantitative assay of junB mRNA completes the scale of laboratory approaches in inflammation and among other pathological conditions.

Chronic overcrowding decreases cytoplasmic free calcium levels in T lymphocytes of aged CBA/CA mice

Intracellular calcium concentration is a sensitive marker of the homeostasis of living cells, and its increase is an essential step of T lymphocyte activation. Changes in the environment provoke an adaptive stress-response of the organism. In our present work we have investigated the effect of chronic overcrowding on resting and lectin-stimulated cytoplasmic free calcium concentration of splenic T lymphocytes from young and aged CBA/CA mice (50 animals total). The animals were kept under 'normal' (68 cm2/animal) or 'overcrowded' (22 cm2/animal) conditions for 3 months. Young animals showed no change in resting and stimulated calcium after overcrowding. T cells from aged mice, however, displayed significantly smaller levels of both resting and lectin-stimulated intracellular calcium concentration (p < 0.01 each), as compared to those of the non-stressed, aged animals. This inadequate adaptation in the calcium metabolism of T lymphocytes may significantly contribute to the diminished immune response of the aged in stress.

Long-lasting persistence of elevated sister-chromatid exchange frequencies induced by perinatal benzo(a)pyrene treatment in rat bone-marrow cells

In this work the possibility that a mutagenic factor acting in utero or in the perinatal period might lead to elevated mutagenic rates in bone-marrow cells after a considerable period of time was examined. An aromatic hydrocarbon, benzo(a)pyrene was used as the test substance. Benzo(a)pyrene treatments resulted in significantly higher sister-chromatid exchange (SCE)-frequencies in both fetal and neonatal groups in both sexes, even four months after exposure. In a second experiment we examined whether mutagenic exposure suffered in utero could make the individual more susceptible to mutagenic effects in adulthood. Preliminary results indicate that such a possibility could exist.

Are intra- and suprasellar masses detected by CT and MR really tumours?

The difficulties of differential diagnosis between intra- and suprasellar tumours resp. inflammatory processes are discussed, based on three personal cases. In all three computed tomography (CT) and magnetic resonance imaging (MR) had demonstrated a tumour, but the clinical signs with discrepancies between radiological and clinical findings were pointing to an inflammatory process. The correct diagnosis of an inflammation was achieved by co-operation between neurologist, neurosurgeon, otologist and ophthalmologist. An unnecessary neurosurgical operation was avoided and the patients were cured by otological intervention and antibiotic therapy.

Age-dependent modification of aspecific cellular effects of the benzodiazepine flunitrazepam

The experiments presented here demonstrate an aspecific effect of the benzodiazepine derivative flunitrazepam (FNZ). It differs in sites and mechanisms of action, both from benzodiazepine (BZ) specific effects on gamma-aminobutyric acid (GABA) blocking transmission via central BZ receptors and from BZ effects mediated by peripheral BZ receptors. The aspecific effect of FNZ can suitably be examined on isolated and identified neurons of the mollusc Lymnaea stagnalis (pond snail). The physiological sites of action are outside the synaptic zone, on the neuron somatic membrane and affect 'intrinsic' properties of membrane, including calcium, calcium-activated potassium and chloride channels. The aspecific FNZ effect exerts an influence on the metabolism of the cell by decreasing the permeability of the calcium channel, diminishing the excitability of the neuron membrane, and hyperpolarizing the cell, thus potentiating the specific effect of FNZ. The senile alterations of the neuron function intensify the aspecific effects of FNZ to such a degree that it must be taken seriously in consideration in anesthesia of elderly patients.

The effect of epinephrine on the intracellular free calcium of parent and Ki-ras-transfected NIH3T3 cells

Here we describe differences in the formation of the epinephrine-induced Ca2+ transients between parent and Ki-ras-transformed NIH3T3 fibroblasts. These transients proved to be the results of an efflux from both the thapsigargin-sensitive and -insensitive intracellular pools. While the epinephrine-induced detachment of the ras-transformed cells might be due to cytoskeletal and/or cell-matrix alterations.

Age-dependent alteration of neural visual adaptation

Age alterations of neural visual adaptation mechanisms were studied in young, adult and old rats by means of electroretinogram (ERG) registration. The age peculiarities of neural/fast adaptation appear mostly in limit states, partly in the range of low intensity light stimuli about the threshold sensitivity, partly in the range of high intensity light stimuli. In the case of low intensity light stimuli, the increase of light sensitivity in the course of neural dark adaptation was fastest and greatest in adult animals. In the retina of aged animals, no neural adaptation light sensitivity change could be detected about the ERG threshold. In the domain of medium intensity the adaptability of the aged retina is equivalent to that of young and adult ones, whereas its spatial and temporal summation ability gets worse in this domain. High intensity light stimuli rapidly narrow down the functional range of fast neural adaptation mechanism of the aged animal. Receptor cells of aged animals proved to be most vulnerable to glaring illumination and light loading.

Interactions between human and porcine interferons

To investigate the possible interactions between human and porcine interferons (IFNs) in vitro, human transformed (FL) and nontransformed (HEF) cells were treated with either HuIFN alpha and/or gamma and porcine alpha and/or gamma. In both cases the antiproliferative activity was measured to determine the effects of different combinations between human and porcine IFNs on cell proliferation. Combinations of human and porcine IFNs acted mostly antagonistically with exception of IFN combination Hu-alpha/Po-gamma which showed a synergic cooperativity in therms of antiproliferative activity on human transformed cells.

Effect of storage and 60Co irradiation on the antiviral activity and subtype pattern of native human interferon-alpha preparations

The stability of native human leukocyte IFN-alpha was investigated after one year storage at different temperatures, or after sterilization with 60Co-irradiation by determining the total antiviral activity of samples. Inactivation of VSV and Aujeszky virions by 60Co-irradiation was directly related to the radiolysis of samples, indicating the uselessness of this procedure for sterilization of IFN-alpha preparations. The presence and proportion of subtypes in the stored or irradiated preparations (with 50 and 25-70% inactivation, respectively) was analysed by chromatofocusing, comparing their patterns with that of the untreated controls. A logarithmic correlation was found between the pI values and temperature/irradiation sensitivity of subtypes.

Propagation of focal epilepsies and the timing and targeting of surgical interventions. Illustrative case reports

The mirror focus conception assumes propagation of epileptic excitation towards a homotopic area of the contralateral hemisphere inducing secondary focal discharges. Later, independent discharges can be initiated by this new area of epileptogenesis but initiation of seizures of the same or altered symptomatology--and not only interictal discharges--from a mirror focus has yet not been proved. Three cases will be presented where dynamism of the development of temporal lobe mirror focus have been followed. All cases give rise to several questions concerning selection and timing of surgical approach.

gamma-L-glutamyl-taurine (Litoralon) prevents the micronucleus formation induced by mitomycin C

We have examined whether gamma-L-glutamyl-taurine (Litoralon) could prevent the genotoxic action of mitomycin C (MMC) in the rat bone marrow cells using the micronucleus test. Litoralon (0.83 mg/kg) administered concurrently with MMC (0.75 mg/kg) did not exhibit any protective action. Pretreatment with a single dose (0.83 mg/kg) of Litoralon 24 h before the administration of MMC (0.75 mg/kg) prevented the micronucleus-inducing effect of MMC. There was no difference between the efficiencies of a single and multiple Litoralon pretreatments. Since Litoralon is known to exhibit vitamin A-like activity and stimulation of poly-ADP-ribose synthesis, it is presumed that either one of these 2 properties separately, or both in conjunction, can be responsible for the inhibition of micronucleus formation.

Further experiences in the treatment of cystic craniopharyngeomas with yttrium 90 silicate colloid

20 patients suffering from cystic craniopharyngioma were treated with intracavitary irradiation on 25 occasions. The beta emitting radionuclide 90Y silicate colloid was instilled into the cyst or cystic part of the tumour. 17 patients on 22 occasions underwent follow-up CT and ophthalmological examinations 1 to 144 (average: 34) months after the intracavitary radioisotope therapy. An 23 occasions there was an average of 82 to 90% volume decrease of the craniopharyngioma cysts. On two occasions the volume has remained unchanged and the result of the 90Y therapy cannot be evaluated yet. The neuroophthalmological prognosis was good only when a relatively intact optic disc was seen; when the disc was atrophic the visual deterioration proved to be irreversible. Pathologically, it is the fibrotic tissue that is responsible for the shrinkage of the cyst.

Overlapping imprinting of oligopeptides in Chang liver cells. Data on the mechanism of hormone evolution

Imprinting was induced with synthetic oligopeptides in Chang liver cell cultures to test these molecules for signal molecule value. Investigations into imprinting overlaps (cross-imprinting) have shown that all oligopeptides (di-, tetra- and pentapeptides) carrying a terminal proline group were able to imprint the cells for the pentapeptide Tyr-D-Met-Gly-Phe-Pro-NH2, which displayed an outstanding imprinting potential for itself and an extraordinary opioid activity as well. The fact that exclusively the proline-deficient oligopeptide (a tetrapeptide) failed to imprint for the pentapeptide in question, indicates a decisive role of proline in the transformation of molecules to signal carriers (hormones). The pentapeptide in question did imprint for the related molecules (except the dipeptide) but to a much lesser degree than for itself. The marked inferiority of the pentapeptide's cross-imprinting potential to its self-imprinting potential supports the hypothetical implication that a considerable difference between the specific and non-specific binding capacities of a molecule, if not the loss of non-specific binding was an essential prerequisite of transformation to a signal molecule, i.e. of hormone evolution.

Investigation of trigeminal SEP with scalp and deep electrodes

A special technique for stimulating and recording trigeminal somatosensory evoked potential (SEP) is described. Eleven healthy subjects and seven patients with chronically implanted deep electrodes have been investigated. Characteristic polyphasic waves were repeatedly observed. The recording of somatosensory evoked potential following trigeminal stimulation is a more difficult technique. This paper describes data in control subjects with scalp electrodes and data on patients with electrodes in the nucleus ventralis posteromedialis and cortical white matter. Depth recording may provide useful information about the origin, nature, and properties of trigeminal SEP.

The surgery of middle cerebral artery aneurysms

Aneurysms of the middle cerebral bifurcation represent an interesting entity among intracranial saccular aneurysms. Their shape, size, situation, and in particular their relation to the middle cerebral trunk and its branches show wide variations. Topographical analysis of the angiograms offers a great deal of interest in planning surgery. Our experience with 289 patients with middle cerebral artery aneurysms operated on since 1977 are presented. Factors such as number of previous haemorrhages, timing of surgery, preoperative condition, major intraoperative bleeding or brain oedema and delayed postoperative deterioration play a major role in the outcome. Others such as severity of the subarachnoid bleed, age, size of the sac seem to have much less influence.

Computer analysis of some bacteriological, biological and physiochemical parameters of the coastal water of Lake Balaton

Some 61 coastal water samples were taken at four definite points of Balaton Lake. Seventeen parameters of each sample characterizing the quality of the water were studied by means of multiple correlation and regression analysis, one-way variance analysis and by factor analysis with the help of BMD computer program. Uni- and multilateral relationships could be observed among the single parameters. On the basis of the results of factor analysis six factors--phytoplankton system, anthropogenic effect, own bacterial system of the lake, nitrogen circulation, hydrocarbonate and reactive phosphate system and NH+4 circulation--could be separated. Significant qualitative differences could be found along the longitudinal axis of Balaton. It could be also demonstrated that the water of the lake in its present condition is suitable for the proliferation of bacteria. Further and deeper examinations are necessary for a better understanding of the biochemical and biological processes.

Surgical treatment of multiple intracranial aneurysms

Patients with multiple intracranial aneurysms present a great challenge to neurosurgical practice. The presence of one or more additional aneurysms, whether recognized or unrecognized, along with the source of the haemorrhage profoundly changes the outcome. It also alters the timing and strategy of surgery. In this study the experiences gained from 138 cases with a total of 317 aneurysms are discussed. The analysis of the clinical data, our results and the factors influencing the outcome suggest that the risk of clipping all aneurysms simultaneously are less than the risk of a rebleed from an untreated, previously silent sac even in the early postoperative period.

The radiotherapy of cystic craniopharyngioma with intracystic installation of 90Y silicate colloid

The authors describe the intracavital treatment with 90Y silicate colloid in 9 cases of cystic craniopharyngioma. The method has been applied since 1975 in the National Institute of Neurosurgery, Budapest. The intracavital treatment was only one among several applied treatment forms. In all patients a partial removal of the tumour has also been performed. The possibilities of evaluation of the effectiveness of the internal cyst irradiation are therefore limited. In most cases the intracavital treatment resulted in shrinkage of the cyst, or even was followed by its practical disappearence and the condition of the patients shows a decisive improvement. The growth of solid tumour parts is not influenced by this kind of treatment. Therefore the clinical improvement of the patient's condition depends also on the ratio between cyst and solid tumour volume. The optic nerve impairment did not improve in all cases. As a side-effect an oculomotor nerve paresis developed in several patients. Its possible explanations have been discussed, including lasting damage from tumour pressure.

Human interferons alpha and beta have more potent priming activities than interferon gamma

The priming activities of human IFN-alpha, IFN-beta and IFN-gamma were compared on the same antiviral basis using human buffy coat leukocytes stimulated with Sendai virus or concanavalin A (Con A) to produce IFN-alpha or IFN-gamma, respectively. Pretreatment of leukocytes with any type of IFN enhanced their IFN-alpha and IFN-gamma production, but IFN-alpha and IFN-beta had more potent priming activities than IFN-gamma. IFN-alpha and IFN-gamma did not potentiate the priming activity of each other in either the IFN-alpha or the IFN-gamma producing system. Pretreatment of leukocytes with relatively high doses of IFN-alpha or IFN-beta (1000 to 3000 IU/ml) resulted in a 40- to 50-fold increase in the IFN-gamma production of Con A-stimulated leukocytes. This observation will be of use in producing IFN-gamma with a high titre.

Verification of the membrane hypothesis of aging on the identified giant neurons of the snail Lymnaea stagnalis L. (Gastropoda, Pulmonata) by a combined application of intracellular electrophysiology and X-ray microanalysis

The validity of the membrane hypothesis of aging (Zs.-Nagy, 1978) was tested on identified giant neurons of the snail Lymnaea stagnalis L. by using a combination of intracellular microelectrophysiology and X-ray microanalysis of the intracellular water and electrolyte concentrations on the very same cells. The snails were taken from an inbred stock and divided into young, adult and old age groups (3, 12 and 24 mth, respectively). The giant neuron called LPa-2 from the left parietal ganglion was selected for the studies. The resting potential of the cell membrane was recorded by means of intracellular microelectrode technique. The very same cells were then explored by freeze fracture and analyzed by an energy dispersive bulk specimen method of X-ray microanalysis. The resting membrane potential displayed an age-dependent hyperpolarization, the intracellular water content decreased considerably and the intracellular potassium concentration increased almost 90% by old age. The relative passive permeability ratio for potassium (PK) and chloride (PCl) was calculated from the measured data by means of the Goldman-Hodgkin-Katz equation. Such calculations revealed that PK decreases nearly 50% with age causing the increase of the intracellular potassium content, and this is accompanied also by a significant decrease of the PCl. The results support the validity of the membrane hypothesis of aging and are in agreement with the general knowledge regarding the electrophysiological behaviour of the giant neurons of Gastropode snails.

The spread of somatosensory-evoked potentials within the nervous system

Four thalamic and cortical recordings were carried out in 5 patients. The thalamic-evoked potentials were typical and revealed a triphasic complex, but their latencies showed a relatively high standard deviation. They could be divided into two groups according to their latencies, both of which had low SD. These data suggested that there could be two types of latency of thalamic SEP, because the 4 patients' body sizes were very similar. More detailed surface, cortical and depth recordings are needed to resolve these questions.

Different interferon-inducing ability of human adenovirus types in chick embryo cells

Human adenovirus (Ad) types differ in their ability to induce interferon (IFN) in chick cells. Of 12 types investigated, Ad8, Ad12, Ad 18 and Ad 31 proved to be more effective IFN inducers than Ad2, Ad3, Ad4, Ad5, Ad6, Ad7, Ad15 and Ad19. Ultraviolet (UV) irradiation decreased the IFN-inducing ability of the more effective inducers only, indicating that transcription of viral DNA might play a role in IFN induction by these types. DNAs isolated from Ad2, Ad5 and Ad12 alike induced low amounts of IFN in chick cells. The IFN-inducing capacity of phage DNA was similar to that of adenovirus DNA, but induction by non-viral DNA (prokaryotic and eukaryotic) did not result in detectable IFN production. It is assumed that viral DNA and virus particles promote IFN production in different ways. Probably the viral component responsible for IFN induction by the effective Ad types differs from those having lower IFN-inducing ability.

Advantages and drawbacks of some ERG stimulation and data-processing methods

In each group of diseases, electroretinographic (ERG) diagnosis requires optimal stimulation parameters and detection techniques that clearly evidence any deviations from normal values. Television tube light stimulator assemblies and stimulation techniques applying methods of the control theory are very suitable for the dynamic separation of gross ERG components. The advantages and drawbacks of flicker ERG, frequency-characteristic methods and the frequency ranges that provide useful information in data processing are discussed.

The function of the human cerebellum studied by evoked potentials and motor reactions

The authors investigated the cerebellar function of patients with chronic implanted electrodes. The investigations were carried out using elicited compulsion events--evoked potentials and motor reactions--in different functional motor states, i.e., rest and contraction. The compulsion events are the result of motor control processes which eliminate the transient effect of stimuli. In connection with the cerebellum, these motor control processes in some ways mirror the function of the cerebellum. The evoked potentials recorded in the cerebellum have specific features and specific functional dependence as well. On stimulation of the cerebellum, the first effect on motor activity is always inhibitory. Altering the cerebellar function by high frequency stimulation appears to cause cerebellar symptoms such as hypotonia and ataxia.

Multitarget technique in Parkinson surgery

In the past 10 years, experience has been gained with combined VL-thalamotomy, pallidotomy and dentatomy using chronically implanted electrodes in Parkinson's disease. In the vast majority of cases, symptoms ceased surprisingly for 10-14 days just after stereotactic exploration of these motor centers. Clinical neurophysiological investigations (evoked responses, motor effects) show where consecutive lesions will be permanently effective at definitive coagulation. The physiological basis of these findings are discussed and a sophisticated therapeutic protocol is advised.

Evoked responses by physiological sensory inputs in human central motor structures

In human with chronic implanted electrodes physiological evoked responses could be detected from those structures they were thought to be parts mainly of central motor system. Investigating the functional changes of evoked responses to motor states and attention the results have suggested the responses do not sign the centres to treat as directly the sensory inputs i.e. auditory, visual, somatosensory stimuli as motor stimuli.

Frequency resonance investigation of the H reflex

Results of a previous study demostrated transformation of the sustained activity of a muscle into rhythmic, tremor-like activity by stimulation of different motor centres. The optimum for this transformation was in the 4-7 Hz frequency band (resonance band). Sustained rhythmic stimulation with stimuli at 0.1-20 per second caused a normal frequency curve of the H reflex in subjects with intact motor systems. The resonance phenomenon of the frequency curve of the H reflex was in agreement with that found in previous studies stimulating the different motor centres. As this requires connections between spinal and higher motor centres, it is suggested that this investigation is appropriate for a detailed functional study of spinal cord lesions.

The study of recovery and modification of the evoked potentials and motor answers in the motor system

After an electrical stimulus within the motor system there will follow a compulsion, a reflexlike process in functional dependency, naturally in illness (function disturbance) dependency as well. We can detect this process with the evoked potentials at the non-stimulated sites of the motor system and with the motor answers at the periphery. Because the motor system acts as a whole, it is certain that every process at a site has its correlates at the other sites, but the different part of the same process will be in a different grade pronounced (many times in opposite direction) at the different sites. If we want to know something from the basic process and to find the real correlates, we have to compare different evoked potentials within the motor system and motor responses at the periphery, or we have to enhance or depress the whole process or its parts. For the latter the double stimulation technique is suitable, but we have to take into consideration that during this investigation two alternating processes affect each other and therefore the result will not be direct.

Lysosomal enzyme studies after endotoxin administration in normothermia and hypothermia

The LD50 dose of endotoxin results in a considerable increase in the plasma level of acidic phosphatase and beta-glucuronidase. The endotoxin decreases the quantity of gamma-globulin fraction of sera as an effect of neutral lysosomal proteases. In hypothermic rabbits the activity of lysosomal enzymes is increased only slightly after administration of endotoxin and the change in the gamma-globulin level is also more less than in the normothermic animals. The importance of our results in the pathogenesis of inflammation induced by endotoxin is discussed.

Effect of endotoxin and trypsin on the blood pressor response to catecholamines in normo- and hypothermic rabbits

The action of endotoxin, trypsin or hypothermia on the vascular reactivity to catecholamines was investigated in rabbits, and with trypsin in normothermic dogs as well. In rabbits, LD10 of Escherichia coli 0111 endotoxin increased the blood pressor effect of i.v. adrenaline or noradrenaline with maxima at 60-90 min. LD50 endotoxin elicited a vascular hyporeactivity to catecholamines within an hour. 22 hours later, however, a hyperreactivity to catecholamines developed. At this time, repeated administration of LD50 endotoxin did not reduce the increased catecholamine responsiveness. Trypsin (i.v. 1.5 mg/kg) also potentiated the pressor effect of catecholamines in rabbits and dogs with maxima at 5-10 min. Higher trypsin doses induced a hyporeactivity. LD50 endotoxin in a single or a repeated dose after 22 hours did not decrease the blood pressure of cooled rabbits and failed to alter the vascular reactivity to adrenaline or noradrenaline. The blood pressure effect of trypsin differed in character in normo- and hypothermic rabbits, depending on the depth of cooling. Low body temperature eliminated the potentiating effect of trypsin to the blood pressor action of catecholamines. In normothermic rabbits pretreated with amino-pyrine and phenylbutazone, the blood pressure and the catecholamine potentiation effects of endotoxin or trypsin were inhibited or considerably reduced. The results support the significance of altered vascular reactivity to catecholamines under different pathologic conditions where endotoxin and/or proteases may occur.

Effect of osmotic pressure, ionic strength and dibutyryl cyclic adenosine monophosphate on the adhesion of hen erythrocytes

In the presence of lysolecithin at physiological pH it was found that the increase of ionic strength facilitates the adhesion of hen erythrocytes. In this medium, dibutyryl cyclic adenosine monophosphate (DBcAMP) increases the adhesion index of the cells. If the osmotic pressure is elevated without a proper increase of ionic strength, the lysolecithin induced hemolysis and adhesion are found to be lacking.

Functional changes of the aging rat retina in relation to the modifications of the ERG components

the intact eye of Wistar rat was stimulated with continual periodic light signals in the range of 0,001-500 lux and from 0,01 cps. up to the fusionfrequency. Using square-wave light stimuli of the frequency range from 0,01 to 0,1 cps. and intensity diapason of 0,1-1,0 lux the scotopic electroretinogram (ERG) consists of the following waves: b, b-negative, c, d, d-positive, respectively. At the beginning of the light sensitivity range, that is near above the threshold, on one part and over a stimulus intensity of 10 lux, on the other the ERG becomes more simple and looks appr. like a direct current (DC) response. Along with aging the ERG undergoes changing. The light sensitivity of the eye proved to be decreased, especially in the short wave range of the spectrum. Thus the ERG threshold becomes increased. The DC components are less apparent. The fast elements of high amplitudes are also missing. The slope of the frontal and descending part of the wave b gets lower. The fusion-frequency is lower with old animals as well. The spontaneous physiological biopotential noise level is significantly higher and the synchronity of elements participating in generating the ERG wave is less. Additionally a considerable great slowing-down of the adaptation processes were observed. Using light signals of different wave forms, it may be established, that differentiating ability of the retina declines more rapidly as aging advances than that of its light sensitivity.

The motor mechanism of some types of epilepsy

In the types of epilepsy studied if the irritative epileptic activity evokes a motor response this response will be a special type. The epileptic activity is working on a normal motor system and will affect it in space and time at a special point. From this point of view it is possible to compare-during stimulation of the motor system--the evoked potential and the evoked epileptic potential, i.e. the evoked motor activity and the epileptic motor activity. It appears that--in the types of epilepsy studied--the motor resting state promotes the spontaneous and the evoked epileptic activity or the epileptic evoked motor activity. It is very probable that the epileptic activity does not employ the short, phasic motor responses, but the tonic, automatic, reflex motor ones.