[Importance of personality disorders in epilepsy]

Epilepsy is one of the most common neurological disorders. Therapeutic success shows high variability between patients, at least 20-30% of the cases are drug-resistant. It can highly affect the social status, interpersonal relationships, mental health and the overall quality of life of those affected.
Although several studies can be found on the psychiatric diseases associated with epilepsy, only a few researches focus on the occurrence of personality disorders accompanying the latter. The aim of this review is to help clinicians to recognize the signs of personality disorders and to investigate their connection and interaction with epilepsy in the light of current experiences.
The researches reviewed in this study confirm that personality disorders and pathological personality traits are common in certain types of epilepsy and they affect many areas of patients’ lives. These studies draw attention to the importance of a multidisciplinary approach to this neurological disorder and to provide suggestions about the available help options. Considering the high frequency of epilepsy-related pathological personality traits that can have a great impact on the therapeutic cooperation and on the patients’ quality of life, it important that the neurologist recognizes early the signs of the patient’s psychological impairment. Thus they can get involved in organizing the support of both the patient and their environment by including psychiatrists, psychologists, social and self-help associations.
As interdisciplinary studies show, epilepsy is a complex disease and besides trying to treat the seizures, it is also important to manage the patient’s psychological and social situation. Cooperation, treatment response and quality of life altogether can be significantly improved if our focus is on guiding the patient through the possibilities of assistance by seeing the complexity and the difficulties of their situation.

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New Approach for Untangling the Role of Uncommon Calcium-Binding Proteins in the Central Nervous System

Although Ca²⁺ ion plays an essential role in cellular physiology, calcium-binding proteins (CaBPs) were long used for mainly as immunohistochemical markers of specific cell types in different regions of the central nervous system. They are a heterogeneous and wide-ranging group of proteins. Their function was studied intensively in the last two decades and a tremendous amount of information was gathered about them. Girard et al. compiled a comprehensive list of the gene-expression profiles of the entire EF-hand gene superfamily in the murine brain. We selected from this database those CaBPs which are related to information processing and/or neuronal signalling, have a Ca²⁺-buffer activity, Ca²⁺-sensor activity, modulator of Ca²⁺-channel activity, or a yet unknown function. In this way we created a gene function-based selection of the CaBPs. We cross-referenced these findings with publicly available, high-quality RNA-sequencing and in situ hybridization databases (Human Protein Atlas (HPA), Brain RNA-seq database and Allen Brain Atlas integrated into the HPA) and created gene expression heat maps of the regional and cell type-specific expression levels of the selected CaBPs. This represents a useful tool to predict and investigate different expression patterns and functions of the less-known CaBPs of the central nervous system.

New Approach for Untangling the Role of Uncommon Calcium-Binding Proteins in the Central Nervous System

Although Ca²⁺ ion plays an essential role in cellular physiology, calcium-binding proteins (CaBPs) were long used for mainly as immunohistochemical markers of specific cell types in different regions of the central nervous system. They are a heterogeneous and wide-ranging group of proteins. Their function was studied intensively in the last two decades and a tremendous amount of information was gathered about them. Girard et al. compiled a comprehensive list of the gene-expression profiles of the entire EF-hand gene superfamily in the murine brain. We selected from this database those CaBPs which are related to information processing and/or neuronal signalling, have a Ca²⁺-buffer activity, Ca²⁺-sensor activity, modulator of Ca²⁺-channel activity, or a yet unknown function. In this way we created a gene function-based selection of the CaBPs. We cross-referenced these findings with publicly available, high-quality RNA-sequencing and in situ hybridization databases (Human Protein Atlas (HPA), Brain RNA-seq database and Allen Brain Atlas integrated into the HPA) and created gene expression heat maps of the regional and cell type-specific expression levels of the selected CaBPs. This represents a useful tool to predict and investigate different expression patterns and functions of the less-known CaBPs of the central nervous system.

Short-Term Amygdala Low-Frequency Stimulation Does not Influence Hippocampal Interneuron Changes Observed in the Pilocarpine Model of Epilepsy

Temporal lobe epilepsy (TLE) is characterized by changes in interneuron numbers in the hippocampus. Deep brain stimulation (DBS) is an emerging tool to treat TLE seizures, although its mechanisms are not fully deciphered. We aimed to depict the effect of amygdala DBS on the density of the most common interneuron types in the CA1 hippocampal subfield in the lithium-pilocarpine model of epilepsy. Status epilepticus was induced in male Wistar rats. Eight weeks later, a stimulation electrode was implanted to the left basolateral amygdala of both pilocarpine-treated (Pilo, n = 14) and age-matched control rats (n = 12). Ten Pilo and 4 control animals received for 10 days 4 daily packages of 50 s 4 Hz regular stimulation trains. At the end of the stimulation period, interneurons were identified by immunolabeling for parvalbumin (PV), neuropeptide Y (NPY), and neuronal nitric oxide synthase (nNOS). Cell density was determined in the CA1 subfield of the hippocampus using confocal microscopy. We found that PV+ cell density was preserved in pilocarpine-treated rats, while the NPY+/nNOS+ cell density decreased significantly. The amygdala DBS did not significantly change the cell density in healthy or in epileptic animals. We conclude that DBS with low frequency applied for 10 days does not influence interneuron cell density changes in the hippocampus of epileptic rats.

Amygdala Low-Frequency Stimulation Reduces Pathological Phase-Amplitude Coupling in the Pilocarpine Model of Epilepsy

Temporal-lobe epilepsy (TLE) is the most common type of drug-resistant epilepsy and warrants the development of new therapies, such as deep-brain stimulation (DBS). DBS was applied to different brain regions for patients with epilepsy; however, the mechanisms of action are not fully understood. Therefore, we tried to characterize the effect of amygdala DBS on hippocampal electrical activity in the lithium-pilocarpine model in male Wistar rats. After status epilepticus (SE) induction, seizure patterns were determined based on continuous video recordings. Recording electrodes were inserted in the left and right hippocampus and a stimulating electrode in the left basolateral amygdala of both Pilo and age-matched control rats 10 weeks after SE. Daily stimulation protocol consisted of 4 × 50 s stimulation trains (4-Hz, regular interpulse interval) for 10 days. The hippocampal electroencephalogram was analyzed offline: interictal epileptiform discharge (IED) frequency, spectral analysis, and phase-amplitude coupling (PAC) between delta band and higher frequencies were measured. We found that the seizure rate and duration decreased (by 23% and 26.5%) and the decrease in seizure rate correlated negatively with the IED frequency. PAC was elevated in epileptic animals and DBS reduced the pathologically increased PAC and increased the average theta power (25.9% ± 1.1 vs. 30.3% ± 1.1; p < 0.01). Increasing theta power and reducing the PAC could be two possible mechanisms by which DBS may exhibit its antiepileptic effect in TLE; moreover, they could be used to monitor effectiveness of stimulation.

Histopathological changes induced by selective inactivation of menin on the thyroid gland in RET÷PTC3 and E7 transgenic mice. A study of 77 cases

Multiple Endocrine Neoplasia Type 1 (MEN1) does not involve the thyroid gland, but animal studies have shown that mice with inactivation of menin could develop thyroid pathologies. The objective was to evaluate if the selective inactivation of menin in murine thyroid glands expressing RET÷PTC3 and E7 oncogenes, might induce an increased index of proliferation and a more rapid development of thyroid hyperplasia and÷or tumors. The thyroid glands of 77 mice aged 4-18 months (31 expressing the E7 oncogene and 25 the RET÷PTC3 oncogene) were analyzed for histological changes and Ki67 proliferation index. Fifty-two mice had selective inactivation of menin in the thyroid gland (16 mice with RET÷PTC3 oncogene and 19 mice with E7 oncogene). As compared to wild type, mice with inactivation of menin presented an increased Ki67 proliferation index. Mice presenting the E7 oncogene showed larger thyroid glands with a pattern of diffuse hyperplasia. Mice expressing the RET÷PTC3 oncogene presented larger thyroid glands compared to the wild type mice but smaller compared to E7 mice. The lesions in the RET÷PTC3 group were "proliferative papillary cystic changes" (60%), "cribriform" (16%), "solid" (8%) and a combination of these patterns in the rest of the thyroid glands. The inactivation of menin in the thyroid gland of young mice does not seem to change the histological pattern, but it influences the proliferation of follicular cells. Further molecular studies especially in aged mice are needed to better understand the correlation between certain oncogenes and the inactive status of menin.

Computer modeling of hippocampal CA1 pyramidal cells - a tool for in silico experiments

Objective. In silico experiments use mathematical models that capture as much as possible from the properties of the biological system under investigation. Our aim was to test the publicly available CA1 pyramidal cell models using the same simulation tasks, to compare them, and provide a systematic overview of their properties in order to improve the usefulness of these models as a tool for in silico experiments.

Methods. Parameters describing the morphology of the cells and the implemented biophysical mechanisms were collected from the Model DB database of Sense Lab Project. This data was analyzed in correlation with the purpose for which each particular model was developed. Multicompartmental simulations were run using the Neuron modeling platform. The properties of the action potentials generated in response to current injection, the firing pattern and the dendritic back-propagation were analyzed.

Results. The studied models were optimized to explore different physiological and pathological properties of the CA1 pyramidal cells. We could identify four broad classes of models focusing on: (i) initiation of the action potential, firing pattern and spike timing, (ii) dendritic backpropagation, (iii) dendritic integration of synaptic inputs and (iv) neuronal network activity. Despite the large variation of the active conductances implemented in the models, the properties of the individual action potentials were quite similar, but even the most complex models could not reproduce all studied biological phenomena.

Conclusions. At the moment the “perfect” pyramidal cell model is not yet available. Our work, hopefully, will help finding the best model for each scientific question under investigation.

The loss of Ivy cells and the hippocampal input modulatory O-LM cells contribute to the emergence of hyperexcitability in the hippocampus

Epilepsy is a frequent neurological disorder that affects directly 0.5-1.5% of the world's population. Despite advances regarding therapy, about 30% of patients cannot be relieved of seizures, mainly because the pathophysiological mechanisms are still not elucidated completely. Basket, axo-axonic, bistratified, oriens-lacunosum moleculare (O-LM) and Ivy cells exert spatially and temporary different inhibition on principal neurons. Our aim was to evaluate the alterations of these interneuron populations during epileptogenesis. We induced status epilepticus in male Wistar rats using intraperitoneal pilocarpine injection, which was followed, after a latency period, by spontaneous recurrent seizures (SRS). Nissl staining was used for the analysis of gross morphological changes, whereas triple immunofluorescent-labeled sections (parvalbumin, somatostatin, neuropeptide-Y) were used for differentiation of the selected interneuron types. Putative interneurons identified by their neurochemical contents were quantified, and the cell density was calculated. Although animals developing SRS showed similar behavior, the degree of hippocampal sclerosis was different. In animals with hippocampal sclerotic cell death pattern the density of perisomatic inhibitory neurons was higher, but not significantly. The dendritic inhibitory bistratified cells were preserved, whereas the number of O-LM cells showed a significant decrease. A substantial loss was observed in the number and density of Ivy cells. We suggest that the loss of hippocampal input modulatory O-LM cells, and overall excitation controlling Ivy cells, has a role in the emergence of hyperexcitability. In the same time, alterations of output controlling interneurons might contribute to the propagation of the pathological synchronization to the cortex.

Dose-dependent pharmacokinetics and brain penetration of rufinamide following intravenous and oral administration to rats

Rufinamide is a third-generation antiepileptic drug, approved recently as an orphan drug for the treatment of Lennox-Gastaut syndrome. Although extensive research was conducted, its pharmacokinetics in rats was not described. This work addresses that area by describing in a rapid pharmacokinetic study the main pharmacokinetic properties of rufinamide at three different doses of 1 mg/kg body weight (bw), 5 mg/kg bw, and 20 mg/kg bw. Furthermore, total brain concentrations of the drug were determined in order to characterize its brain-to-plasma partition coefficient. Adult Wistar male rats, weighing 200-450 g, were administered rufinamide by intravenous and oral routes. Rufinamide concentrations from plasma samples and brain tissue homogenate were determined using a liquid chromatography-mass spectrometric method and pharmacokinetic parameters were calculated. The mean half-life was between 7 and 13 h, depending on route of administration--intravenously administered drug was eliminated faster than orally administered drug. Mean (S.E.M.) total plasma clearance was 84.01 ± 3.80 ml/h/kg for intravenous administration, while the apparent plasma clearance for oral administration was 95.52 ± 39.45 ml/h/kg. The mean (S.E.M.) maximum plasma concentration reached after oral administration of 1 mg/kg bw and 5 mg/kg bw was 0.89 ± 0.09 μg/ml and 3.188 ± 0.71 μg/ml, respectively. The median (range) time to reach maximum plasma concentration (t(max)) was 4 (2-8)h. Mean (S.E.M.) brain-to-plasma concentration ratio of rufinamide was 0.514 ± 0.036, consistent with the brain-to-plasma ratio calculated from the area under curves (AUC(0-t)) of 0.441 ± 0.047. No influence of dose, route of administration, or post-dosing time was observed on brain-to-plasma ratio.

The inner representation of the external world - from conditioned reflexes to high level mental functions in the light of Nobel Prizes

In this paper the seminal results of the 2014 Nobel Prize in Physiology or Medicine Laureates are presented. First, a historical review of the development of our knowledge is provided along with the major paradigm shifts, by looking at the Nobel prizes awarded in the field of neuroscience in the last 110 years. We outline the major discoveries that were necessary for humankind to pass through the road leading to the remarkable understanding of high level mental functions, which led to this year’s Nobel Prize award. Next, the ground breaking discoveries of this year Nobel laureates are presented, which provide insights how neural representations of the environment are formed in the association cortices. These cortical areas are many synapses away from sensory receptors and motor outputs, and their activity do not reflect directly the activation patterns of the receptor population, but depends more strongly on intrinsic cortical computations. We also present how ensembles of specialized cells work together to compute complex cognitive functions and behaviour.

Cortical epileptogenesis of slowly kindled freely moving rats

Objective. Epilepsy is a neurological disorder that can be caused by many underlying pathologies. The epileptic and interictal manifestations that appear during the progression of chronic epilepsy are still not understood completely. One of the most frequent forms of this disease is temporal lobe epilepsy in which is clear involvement of the hippocampal formation. In order to study the electrografic progression of untreated seizures we used amygdala kindling in freely moving rats. Methods. Seven animals were implanted with bilateral hippocampal and prefrontal electrodes. A bipolar electrode, implanted in the lateral nuclei of the left amygdala was used for stimulation. The kindled group of animals was stimulated daily with the minimum current intensity needed to reach the afterdischarge threshold. Behavioral changes during kindling were scored according to the Racine scale. Results. The average seizure severity on the Racine scale was 2.6±0.4 by day 6 and 4.4±0.6 by day 20. The first spontaneous seizures appeared after 31 days of stimulation. During spontaneous seizures the preictal spike full width at half maximum increased gradually from 51±4msec to 110±5msec (p < 0.05) whereas the amplitude of the negative field potential deflection increased by 62% (p < 0.05). Conclusions. Our study showed that the progression of temporal lobe epilepsy, as seen in humans, can be reproduced in the kindling model with high fidelity. This study confirms in vivo the increase in preictal spike duration as well as the increase of the amplitude of negative field potential deflection during the preictal period.

Morphological identification of neuron types in the rat hippocampus

The cerebral cortex ensures an optimal interaction of mammals, including humans, with their environment, by encoding, storing and combining information about the surrounding world and the internal milieu. Probably the simplest and the most popular region for studying the cortical network is the hippocampal CA1 area, because it has the least heterogeneous neuronal population, the somata and dendrites of principal neurons (pyramidal cells) are arranged into well defined layers and the extrinsic and intrinsic inputs are segregated. The relatively homogeneous pyramidal cell population is supported by a very heterogeneous GABAergic interneuron population, which provides not only general inhibition, but also regulates the precise timing of pyramidal cell activity. Interneurons usually innervate distinct domains of the surface of their target cell. The strategic placement of inhibitory synapses, indicate that GABAergic interneurons belonging to different classes serve distinct functions in the hippocampal network. Neuron types are usually defined according to various morphological, molecular and physiological features. Under typical experimental conditions only some of these parameters are available, therefore an important scientific question is: which partial measures are sufficient for correct recognition of a class of cell. By immunohistochemistry it is possible to stain all neurochemically identical neurons in a given brain region, therefore it is the most widely used method for identifying neuron classes. This review presents the neuron types identified so far in the area CA1 of the rat hippocampus with special emphasis on the immunocytochemical characterization of these cells.

Quantitative characterization of regional differences in the GABAA-receptor alpha1-subunit mRNA expression in the rat brain

Inhibition in the central nervous system is largely mediated by local-circuit neurons that release GABA (gamma-amino-butyric acid). GABAA-receptors play a major role in virtually all brain physiological functions and serve as targets for numerous classes of drugs, used both in clinical practice and as research tools. These receptors are heteropentamers, alpha1 being the most widely occurring subunit; therefore it is the best candidate to be studied in pathological conditions where the inhibitory system might be altered (e.g. epilepsy). We compared quantitatively the regional distribution of GABAA-receptor alpha1-subunit (GABAAR-alpha1) expression in three brain areas: neocortex, hippocampus and cerebellum by RT-qPCR. TaqMan probe was used in order to avoid detection of non-specific amplification products and synaptophysin as internal control. This substance was chosen because it has a stable expression restricted to neurons, and contrary to GAPDH, the most commonly used reference gene for expression analysis, synaptophysin expression is not modified in animal models of epilepsy. Expression of synaptophysin was higher than expression of GABAAR-alpha1 in all samples from the central nervous system. The latter was significantly different among the studied brain areas. It was the smallest in the hippocampus, intermediate in the neocortex and the highest in the cerebellum. Interanimal differences were small for any brain region under study. These results indicate that combination of TaqMan real-time PCR method with synaptophysin as internal control can reliably measure the relative expression of GABAAR-alpha1 mRNA, and are suitable for investigating the modifications that appear under pathological conditions and/or diverse experimental paradigms.

Higher cigarette taxes--healthier people, wealthier state: the Hungarian experience

OBJECTIVE

To prove that higher cigarette taxes eventually decrease smoking and do also increase state incomes from tobacco taxes by using Hungarian figures.

METHOD

Collection and analysis of available data on tobacco use, levels of excise and value added taxes on tobacco products and state incomes originating from the tobacco sector.

CONCLUSIONS

In Hungary, regular tobacco tax increases resulted in decreased cigarette consumption and its lower prevalence figures in some population groups. State incomes have increased in spite of regular cigarette tax raises. Therefore, there is on conflict of interest between the health and finance portfolios in supporting further tobacco tax increases. Hungary should use regular, above the inflation tobacco tax raises as means for improving population health. Tobacco control advocates should prevent tobacco companies' attempts aimed at deterring decision makers from supporting such tax policies.

Tobacco industry efforts to erode tobacco advertising controls in Hungary

OBJECTIVE

To review strategies of transnational tobacco companies (TTCs) at creating a favourable advertising environment for their products in Hungary, with special regard to efforts resulting in the liberalisation of tobacco advertising in 1997.

METHOD

Analysis of internal tobacco industry documents relevant to Hungary available on the World Wide Web. Transcripts of speeches of members of the Parliament during the debate of the 1997 advertising act were also reviewed.

CONCLUSIONS

The tobacco companies not only entered the Hungarian market by early participation in the privatisation of the former state tobacco monopoly, but also imported theirsophisticated marketing experiences. Evasion and violation of rules in force, creation of new partnerships, establishment and use of front groups, finding effective ways for influencing decision makers were all parts of a well orchestrated industry effort to avoid a strict marketing regulation for tobacco products.

Effects of variability in anatomical reconstruction techniques on models of synaptic integration by dendrites: a comparison of three Internet archives

The first step in building a realistic computational neuron model is to produce a passive electrical skeleton on to which active conductances can be grafted. For this, anatomically accurate morphological reconstructions of the desired cell type are required. In this study compartmental models were used to compare from a functional perspective three on-line archives of rat hippocampal CA1 pyramidal cell morphologies. The topological organization of cells was found to be similar for all archives, but several morphometric differences were observed. The three-dimensional size of the cells, the diameter and tortuosity of dendrites, and the electrotonic length of the main apical dendrite and of the branches in stratum lacunosum moleculare were dissimilar. The experimentally measured kinetics of somatically recorded inhibitory postsynaptic currents evoked in the stratum lacunosum moleculare (data from the literature) could be reproduced only using the archives that contained cells with an electrotonically short main apical dendrite. In the amplitude attenuation of the simulated postsynaptic currents and the voltage escape from the command potential under voltage clamp conditions, a two- to three-fold difference was observed among archives. Upon activation of a single model synapse on distal branches, cells with low dendritic diameter showed a voltage escape larger than 15 mV. The diameter of the dendrites influenced greatly the results, emphasizing the importance of methods that allow an accurate measurement of this parameter. Our results indicate that there are functionally significant differences in the morphometric data available in different archives even if the cell type, brain region and species are the same.

Tobacco industry efforts to keep cigarettes affordable: a case study from Hungary

OBJECTIVE

To review strategies of multinational tobacco companies aimed at keeping tobacco products affordable to smokers in Hungary and to provide background information on the Hungarian request for the delayed introduction of minimum European Union tobacco excise duty levels.

METHOD

Review of internal tobacco industry documents available on the World Wide Web, downloaded between 26 July 2001 and 31 October 2002.

CONCLUSIONS

Appropriate pricing strategies and lobbying for low tobacco tax policies were used by the tobacco industry in Hungary to keep cigarettes affordable to the public. During the 1990s and in the early 2000s transnational tobacco companies (TTCs) were still able to prevent substantial cigarette price rises, which would have been desirable for more effective control of Hungarian tobacco use. Strategies used by TTCs included the creation of new partnerships, use of supportive MPs, communication around tobacco tax issues and also the successful management of the differences in approaches used by individual companies regarding taxation of tobacco products. These resulted in the adoption of governmental policy aimed at delaying the introduction of the EU directive on the minimum tax levels of retail prices of cigarettes.

Hungry for Hungary: examples of tobacco industry's expansionism

OBJECTIVE

To give an overview of available internal tobacco industry documents on the transnational tobacco companies' (TTCs) efforts to enter the new market of the emerging democracy of Hungary and how it developed allies in its efforts at resisting tobacco control regulations.

METHOD

Internal tobacco industry documents relevant to Hungary, available on the World Wide Web, were searched between 26 July and 30 November 2001. Documents on the identification of Central and Eastern Europe (CEE) as a great market potential have been reviewed; another set of reviewed documents are of particular relevance to Hungary, as they indicate who the main partners of the industry are.

CONCLUSIONS

TTCs not only invaded the markets of the fragile new CEE democracies by making their product widely available, but also introduced sophisticated lobbying and marketing tactics. TTCs will try to shape the country's regulatory framework in a manner to help increase their profits. The fiercer the reaction of TTCs against a planned regulatory measure is, the more impact on the health of the population could be expected from the introduction and enforcement of that measure.

Peer education of tobacco issues in Hungarian communities of Roma and socially disadvantaged children

OBJECTIVE

The aim of this demonstration program was to examine the effectiveness of peer education in disseminating tobacco related information and influencing knowledge, attitudes and beliefs related to smoking in socially disadvantaged youth communities.

METHOD

Peer educators were trained to become messengers of tobacco issues. Intervention sites were selected. Self-administered questionnaires were used to assess the effectiveness of interventions. Recommendations were drawn up on the inclusion of peer conducted health education into the comprehensive program of the Ministry of Health to improve the health situation of Roma (Gypsy) and disadvantaged population groups.

RESULTS

Peer educators were recognised as trustworthy mediators of tobacco related information. Interventions resulted in an improved level of knowledge of and changes in attitudes towards smoking in the targeted youth communities.

CONCLUSIONS

The program demonstrated that peer education is an effective tool to raise awareness on smoking issues in communities of Roma and disadvantaged children, when multiple socio-cultural-environmental factors facilitate the taking up of unhealthy habits. If disseminated, this tool could be effective in helping reduce teenage smoking in these communities.

Effect, number and location of synapses made by single pyramidal cells onto aspiny interneurones of cat visual cortex

1. Dual intracellular recordings were made from synaptically coupled pyramidal cell-to-interneurone pairs (n = 5) of the cat visual cortex in vitro. Pre- and postsynaptic neurones were labelled with biocytin, followed by correlated light and electron microscopic analysis to determine all sites of synaptic interaction. 2. Pyramidal neurones in layers II-III elicited monosynaptic EPSPs in three distinct classes of smooth dendritic local-circuit neurones, namely basket cells (n = 3), a dendrite-targeting cell (n = 1) and a double bouquet cell (n = 1). Unitary EPSPs in basket cells were mediated by one, two, and two synaptic junctions, whereas the pyramid-to-dendrite-targeting cell and pyramid-to-double bouquet cell interaction were mediated by five and seven synaptic junctions, respectively. Recurrent synaptic junctions were found on all somato-dendritic compartments, with a tendency to be clustered close to the soma on the double bouquet and dendrite-targeting cells. The latter interneurones were reciprocally connected with pyramidal cells. 3. Unitary EPSPs had an average peak amplitude of 1005 +/- 518 microV, fast rise times (10-90%; 0.67 +/- 0.25 ms) and were of short duration (at half-amplitude, 4.7 +/- 1.0 ms). Their decay was monoexponential (tau = 7.8 +/- 4.3 ms) at hyperpolarized membrane potentials and appeared to be shaped by passive membrane properties (tau = 9.2 +/- 8.5 ms). All parameters of concomitantly recorded spontaneous EPSPs were remarkably similar (mean amplitude, 981 +/- 433 microV; mean rise time, 0.68 +/- 0.18 ms; mean duration, 4.7 +/- 1.7 ms). 4. In all three pyramidal-to-basket cell pairs, closely timed (10-50 ms) pairs of presynaptic action potentials resulted in statistically significant paired-pulse depression, the mean of the averaged second EPSPs being 80 +/- 11% of the averaged conditioning event. The overall degree of paired-pulse modulation was relatively little affected by either the amplitude of the preceding event or the inter-event interval. 5. The probability density function of the peak amplitudes of the unitary EPSPs could be adequately fitted with a quantal model. Without quantal variance, however, the minimum number of components in the model, excluding the failures, exceeded the number of electron microscopically determined synaptic junctions for all five connections. In contrast, incorporating quantal variance gave a minimum number of components which was compatible with the number of synaptic junctions, and which fitted the data equally well as models incorporating additional components but no quantal variance. For this model with quantal variance with the minimum number of components the estimate of the quantal coefficient of variation ranged between 0.33 and 0.46, and the corresponding quantal sizes ranged between 260 and 657 microV. The peak EPSP amplitudes in two of the four connections with more than one synaptic junction could be adequately described by a uniform binomial model for transmitter release. 6. In conclusion, at least three distinct interneurone classes receive local excitatory pyramidal cell input which they relay to different compartments on their postsynaptic target neurones. The reliability of transmission is high, but the fast time course of the EPSPs constrains their temporal summation. Due to the relatively small amplitude of unitary EPSPs several convergent inputs will therefore be required to elicit suprathreshold responses.

Neuroplastic changes in the hypothalamic arcuate nucleus: the estradiol effect is accompanied by increased exoendocytotic activity of neuronal membranes

1. In the rat hypothalamic arcuate nucleus, estradiol induces coordinated changes in the number of axosomatic synapses, the amount of glial ensheathing, and the ultrastructure of the membrane of neuronal somas. In the present study we used conventional electron microscopy and freeze-fracture to examine cellular mechanisms responsible for the estradiol-induced changes at the membrane level. 2. In freeze-fracture replicas taken 10-60 min and 24 hr after injection of 17 beta-estradiol to adult ovariectomized females, it was found that there was a rapid increase in the number of exoendocytotic images that reached a plateau by 30 min. 3. In thin sections from animals injected 24 hr earlier we demonstrated a significant increase in coated vesicles in the periphery of the neurons and coated pits in the perikaryal membranes and decreased axosomatic synapses. 4. We conclude that these morphological alterations are signaling estrogen-induced transport and/or turnover of perikaryal membrane constituents and extracellular components which may affect interneuronal and neuroglial interactions.

Modulation by thyroid hormones of the development of external plexiform layer in the rat olfactory bulb

Width of the external plexiform layer in olfactory bulbs and mean area of mitral and granule cell dendritic and glial processes were measured of normal, hypo- and hyperthyroid rat pups at the age of 24 days. Hypothyroidism was induced by treating the rats with a reversible goitrogen 6-n-propyl-2-thiouracil dissolved in their drinking water, while the hyperthyroid group was given water containing thyroxine. The 6-n-propyl-2-thiouracil treatment was begun on gestational day 18 and on the day of birth. Thyroxine treatment started on the day of birth. Both treatments were continued till the day of sacrifice. A significant decrease in the width of the external plexiform layer of the olfactory bulb in the prenatally 6-n-propyl-2-thiouracil treated group and a significant increase in the width of the external plexiform layer of the hyperthyroid group was shown by the Student's paired t-test. The areas of neuronal and glial processes were measured at electron microscopic level by using an IBAS image analysing system. A significant decrease was found by the Kruskal-Wallis test and Dunn's range test in the mean area of (1) mitral cell dendrites in the prenatal 6-n-propyl-2-thiouracil treated group, (2) granule cell dendrites in both the postnatally 6-n-propyl-2-thiouracil treated and in the hyperthyroid groups and (3) glial processes in the thyroxine treated group comparing to controls.

Physiological properties of anatomically identified basket and bistratified cells in the CA1 area of the rat hippocampus in vitro

Basket and bistratified cells form two anatomically distinct classes of GABAergic local-circuit neurons in the CA1 region of the rat hippocampus. A physiological comparison was made of intracellularly recorded basket (n = 13) and bistratified neurons (n = 6), all of which had been anatomically defined by their efferent target profile (Halasy et al., 1996). Basket cells had an average resting membrane potential of -64.2 +/- 7.2 vs. -69.2 +/- 4.6 mV in bistratified cells. The latter had considerably higher mean input resistances (60.2 +/- 42.1 vs. 31.3 +/- 10.9 M Ohms) and longer membrane time constants (18.6 +/- 8.1 vs. 9.8 +/- 4.5 ms) than basket cells. Differences were also apparent in the duration of action potentials, those of basket cells being 364 +/- 77 and those of bistratified cells being 527 +/- 138 microseconds at half-amplitude. Action potentials were generally followed by prominent, fast after-hyperpolarizing potentials which in basket cells were 13.5 +/- 6.7 mV in amplitude vs. 10.5 +/- 5.1 in bistratified cells. The differences in membrane time constant, resting membrane potential, and action potential duration reached statistical significance (P < 0.05). Extracellular stimulation of Schaffer collateral/commissural afferents elicited short-latency excitatory postsynaptic potentials (EPSPs) in both cell types. The average 10-90% rise time and duration (at half-amplitude) of subthreshold EPSPs in basket cells were 1.9 +/- 0.5 and 10.7 +/- 5.6 ms, compared to 3.3 +/- 1.3 and 20.1 +/- 9.7 ms in bistratified cells, the difference in EPSP rise times being statistically significant. Basket and bistratified EPSPs were highly sensitive to a bath applied antagonist of non-N-methyl-D-aspartate (NMDA) receptors, whereas the remaining slow-rise EPSP could be abolished by an NMDA receptor antagonist. Increasing stimulation intensity elicited biphasic inhibitory postsynaptic potentials (IPSPs) in both basket and bistratified cells. In conclusion, basket and bistratified cells in the CA1 area show prominent differences in several of their membrane and firing properties. Both cell classes are activated by Schaffer collateral/commissural axons in a feedforward manner and receive inhibitory input from other, as yet unidentified, local-circuit neurons.

Histology and histochemistry of intervertebral discs of rats participated in spaceflight

The qualitative and quantitative histological and histochemical changes in the structure and macromolecular composition of lumbar intervertebral discs of rat during a 12.5-day space flight (Cosmos 1887 biosatellite) were determined using light and polarization microscopy. Semiquantitative histochemical, topo-optical reactions were measured and evaluated by retardation values of birefringence. (a) Lateral expansion and accumulation of the notochordal cells in the nucleus pulposus was observed in contrast with the vivarium control, where the chondroid cells dominated. (b) The cartilage and plate showed a swelling, which consisted mainly of hypertrophied cells sometimes with mild extracellular mineralization. (c) In the external zone of annulus fibrosus and cartilage end plate a mild decrease of orientation of collagen fibers was found. (d) A significant increase of orientation of hyase sensible glycosaminoglycans in the internal zone of annulus fibrosus and nucleus pulposus was observed. (e) In the external and internal zones of annulus fibrosus an increase of orientation of glycoproteids was revealed. The alterations of macromolecular components of intervertebral discs, cartilage end plates, and the osteoporotic changes of the lumbar vertebral bodies producing the looser structure of vertebral column after 12.5 day space flight suggest the necessity of the common evaluation of these structures, and may explain the heavy spinal pains of astronauts.

Effect of short- and long-term spaceflight on the contractile properties of rat skeletal muscles with different functions

In the Cosmos biosputnik 1514, 1667, 1887, 2044 and 1129 the rats 5, 7, 12,5, 15, 18,5 days were in weightlessness state. Due to the adaptation of the skeletal muscles' weightlessness the adaptation was different in various muscles, which depends on the time of participation in antigravitation, the composition of the fibers and from the biometrical characteristics. In different muscles, the changing of the metabolism and the structure of the muscles more than likely in connection with the changing of the myosin subordinate unit compositions. In our experiments we had studied, as to how the muscular atrophy changes, does it increase all the time, or does it balances out after reaching a certain stage.

[Difficulties in recognition and treatment of lethal midline granuloma and otolaryngologic and radiotherapeutic practice]

The authors report on two cases of a "lethal midline granuloma". The first patient was treated by irradiation and chemotherapy. He lives for the last three and a half years in complete remission. The established diabetes did not affect the healing process. In the second case only a palliative irradiation was practicable because of the extreme tumour propagation, but the result was nevertheless good.

Effects of urethan on lymphokine-producing activity of lymphocytes and on some functions of peritoneal macrophages in rats

Effects of urethan on some functions of blood lymphocytes and peritoneal macrophages (PMs) of rats were studied in in vivo and in vitro experiments. The in vitro lymphokine (LK) producing activity of lymphocytes in the presence of specific antigen was depressed by urethan administered 1-5 days before the BCG sensitization. However, the drug injected after the BCG sensitization was not effective on the LK production. Urethan added to the cultures of previously BCG-primed lymphocytes did not influence the LK production. The sensitivity of glycogen-provoked PMs (pPM) to LK-induced activation and, at the same time, the 125I-IgG2a binding capacity as well as the EA rosette formation of the provoked PMs were depressed by urethan administered 1-5 days before the lavage of PMs. These functions of resident PMs (rPM) were not altered by the drug treatment. Urethan added to the cultures of resident or provoked PMs proved to be ineffective. These results led to the conclusions that urethan, after its in vivo metabolic conversion, causes an impairment of the macrophage functions in the inductive phase of the immune response and this event may be the crucial point in the immunosuppressive effect of urethan.

Effects of lymphokines on fibrinolysis and kinin generation in human plasma

Supernatants from Con-A-stimulated human lymphocytes containing leukocyte migration inhibitory factor, skin reactive factor and procoagulant activities were tested for their effect on fibrinolysis and kinin generation. The supernatants of stimulated lymphocytes activated the fibrinolysis and generated kinin in human plasma. These results are discussed from the aspect of cell-mediated (type IV) immune inflammation.

Macrophage disappearance reaction induced by lymphokines

Macrophage disappearance reaction was induced in normal (non-sensitized) guinea pigs by human lymphokines deriving from Con A-stimulated lymphocytes, by ellagic acid (an activator of intrinsic coagulation) and by thromboplastin (an activator of extrinisic coagulation). The results are discussed from the aspect of the pathomechanism of macrophage disappearance reaction.

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.

Local effect of single stranded polyadenylic acid on passive cutaneous anaphylaxis in mice

Single stranded polyadenylic acid (Poly A) administered locally inhibited passive cutaneous anaphylaxis in mice. In experiments performed by equilibrium dialysis Poly A was able to bind histamine. The association constant of the reaction was determined, Ka = 1.3 +/- 0.2 x 10(5) I/M. One Poly A molecule can bind maximally two molecules of histamine dichloride. Poly A inhibited the antigen-induced release of histamine from the peritoneal rat mast cells when it was given together with sensitizing antibodies.

Specificity of bovine thrombin and reptilase for mammalian plasmas

The effect of bovine thrombin and reptilase was investigated on plasmas of ten species of five vertebrate classes. It was established that both enzymes have an expressed specificity for mammalian plasmas, however, their narrower species specificity is different. These comparative coagulation studies, their significance in the laboratory examination also contribute to the analysis of evolution of clotting factors.