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B Kocsis

Publications and source records attributed to B Kocsis.

At least 19 recordsLinked to original sources
PubMed2006

Debye screening of dislocations.

Debye-like screening by edge dislocations of some externally given stress is studied by means of a variational approach to coarse grained field theory. Explicitly given are the force field and the induced geometrically necessary dislocation (GND) distribution, in the special case of a single glide axis in 2D, for (i) a single edge dislocation and (ii) a dislocation wall. Numerical simulation demonstrates that the correlation in relaxed dislocation configurations is in good agreement with the induced GND in case (i). Furthermore, the result (ii) well predicts the experimentally observed decay length for the GND developing close to grain boundaries.

Journal Article↗
PubMed2006

Human astroviruses in raw sewage samples in Hungary.

AIMS: Routine procedures for monitoring viruses in water samples have not been drawn up for the water-microbiology screening panel. Enteric viruses, including astroviruses, are able to persist under environmental conditions and may cause public health problems by contaminating natural and drinking water resources. The aim of this study was to detect human astroviruses (HAstVs) from raw wastewater samples. METHODS AND RESULTS: To obtain data on whether human astroviruses are shed in the environment, 35 raw sewage samples from 22 sewage plants in different regions of Baranya County, Hungary were tested for astrovirus using a polyethylene glycol method for concentration and a guanidinium thiocyanate-silica procedure for extraction of viral RNA. Reverse transcription-polymerase chain reaction (RT-PCR) with HAstV-specific primer pairs was used for amplification and the specificity of amplicons was confirmed by nucleotide sequencing and phylogenetic analysis. Among the 35 raw sewage samples, 15 (43%) contained HAstV and by sequence analysis, 10 genotype HAstV-1 and one genotype HAstV-2 were identified. CONCLUSIONS: The high detection rate of astroviruses we encountered in this study provide convincing evidence that HAstVs circulate at a relatively high frequency in the Hungarian population. No correlation between the standard indicators of faecal pollution and the presence of HAstVs was found. SIGNIFICANCE AND IMPACT OF THE STUDY: Our study is the first report on detection of HAstV in sewage in Hungary and suggests that HAstV might be potent indicators of viral pollution in environmental specimens.

Environmental Monitoring↗
PubMed2006

Activation of alpha7 acetylcholine receptors augments stimulation-induced hippocampal theta oscillation.

In the septohippocampal formation alpha7 nicotinic receptors (alpha7 nAChRs) are predominantly expressed by neurons well positioned to modulate hippocampal theta oscillation, such as GABAergic interneurons in the hippocampus, and by both GABAergic and cholinergic septal neurons. In the present experiments, we evaluated the efficacy of the recently developed selective alpha7 nAChR agonist PNU-282987 on hippocampal theta oscillation in anaesthetized rats. This compound shows high affinity for the rat alpha7 nAChRs (Ki = 26 nM) but a negligible activity at other nAChRs. Systemic administration of PNU-282987 significantly enhanced the power (by 40%) of hippocampal theta oscillation induced by electrical stimulation of the brainstem reticular formation. In contrast, the amnesic and muscarinic receptor antagonist scopolamine significantly decreased the power (by 68%) of the stimulation-induced theta oscillation. Given the connection between hippocampal theta oscillation and cognitive processes, it is proposed that precognitive actions of alpha7 nAChR agonists could be mediated, at least in part, by modulation of hippocampal oscillatory activity.

Animals↗
PubMed2003

Electrophysiological evidence for convergence of inputs from the medial prefrontal cortex and lateral habenula on single neurons in the dorsal raphe nucleus.

Neuronal projections to the dorsal raphe nucleus (DRN) from the medial prefrontal cortex (mPFC) and lateral habenula nucleus (LHb) provide the two key routes by which information processed by mood regulatory, cortico-limbic-striatal circuits input into the 5-HT system. These two projections may converge as it appears that both activate local GABAergic neurons to inhibit 5-HT neurons in the DRN. Here we have tested this hypothesis by measuring the effect of stimulation of the mPFC and LHb on the activity of 5-HT and non-5-HT, putative gamma-amino butyric acid (GABA) neurons in the DRN using extracellular recordings in anaesthetized rats. A total of 119 5-HT neurons (regular, slow firing, broad spike width) and 21 non-5-HT, putative GABA neurons (fast-firing, narrow spike width) were tested. Electrical stimulation of the mPFC or LHb caused a poststimulus inhibition (30 ms latency) of 101/119 5-HT neurons, of which 61 (60%) were inhibited by both the mPFC and LHb. Electrical stimulation of the mPFC or LHb also caused a short latency (12-20 ms) poststimulus facilitation of 10/21 non-5-HT neurons, of which 5 (50%) were activated by both the mPFC and LHb. These data indicate that a significant number of 5-HT neurons and non-5-HT neurons in the DRN are influenced by both the mPFC and LHb. Moreover, the data are compatible with the hypothesis and that there is a convergence of mPFC and LHb inputs on local circuit GABAergic neurons in the DRN which in turn inhibit the activity of 5-HT neurons.

Animals↗
PubMed2002

GABA(B) receptors in the median raphe nucleus: distribution and role in the serotonergic control of hippocampal activity.

Previous studies have shown that serotonergic neurons of the median raphe nucleus have a suppressive effect on theta synchronization in the hippocampus. Median raphe lesion, suppression of 5-HT neuronal activity by administration of GABA(A) receptor antagonist or by glutamate blockade or depletion produced long-lasting non-interrupted hippocampal theta in freely behaving rats independent of behavior and in rats anesthetized with urethane. Serotonergic neurons show a characteristic sleep-wake pattern of activity and there is evidence that GABAergic mechanisms play an important role in their regulation. In this study we analyzed the distribution and subcellular localization of GABA(B) receptors in the midbrain raphe complex using combined 5-HT/GABA(B) receptor immunohistochemistry at the light and electron microscopic levels and studied the effects of their pharmacological manipulation on hippocampal electroencephalographic activity in urethane-anesthetized rats. We found that sustained infusion of the GABA(B) receptor agonist baclofen into the median raphe nucleus, using the microdialysis technique, elicited lasting theta activity in the hippocampus. The effect was antagonized by selective GABA(B) receptor antagonists. The predominant localization of GABA(B) receptors in the median, as well as in dorsal raphe was found on serotonergic neurons which strongly indicates that the increase in theta occurrence after baclofen injection resulted from suppression of the serotonergic output originating from the median raphe. On the electron microscopic level, we found GABA(B) receptors located extrasynaptically indicating that these receptors are preferentially activated by strong inputs, i.e. when GABA released from the synaptic terminals is sufficient to spill over from the synaptic cleft. Such conditions might be satisfied during rapid eye movement sleep when GABAergic neurons in the raphe are firing at their highest rate and in rhythmic synchronized bursts. Our data indicate that midbrain raphe GABA(B) mechanisms play an important role in behavioral state control and in hippocampal activity, in particular.

Action Potentials↗
PubMed2002

Possible glutamatergic/aspartatergic projections to the supramammillary nucleus and their origins in the rat studied by selective [(3)H]D-aspartate labelling and immunocytochemistry.

The supramammillary neurons projecting directly to the hippocampus or indirectly via the septum participate in the regulation of hippocampal theta activity. Inputs to the supramammillary nucleus are only partly specified neurochemically. Glutamate appears to be an excitatory transmitter in this cell group, however, the origin of the glutamatergic afferents is unknown. The present investigations were devoted to study this question. The transmitter-selective [(3)H]D-aspartate retrograde transport method was used injecting the tracer into the lateral subregion of the nucleus. The radioactive tracer was visualized by autoradiography. Non-selective retrograde tracing experiments were also performed for reference injecting wheat germ agglutinin-conjugated colloidal gold into the same supramammillary region. Retrogradely radiolabelled neurons in various numbers were detected in several brain regions including medial septum-diagonal band complex, lateral septum, rostral part of medial and lateral preoptic areas, lateral habenula, ventral premammillary nucleus, apical subregion of interpeduncular nucleus, laterodorsal tegmental nucleus, and dorsal and median raphe nuclei. Radiolabelled neurons in the mentioned raphe nuclei were serotonin-immunonegative. In the non-selective retrograde tracing experiments combined with immunocytochemistry, about 50% of the retrogradely labelled neurons in the raphe nuclei was serotonin-immunonegative, showing that not only serotonergic raphe neurons project to the supramammillary nucleus. The findings indicate that a significant part of the afferents from telencephalic, diencephalic and brainstem regions to the supramammillary nucleus may contain glutamate/aspartate as neurotransmitter. The most important functional implications of these observations concern the role of the supramammillary nucleus in controlling the electrical activity of the hippocampus, and in particular the generation and maintenance of the theta rhythm.

Animals↗
PubMed2001

Synthesis and antibacterial study of unsaturated Mannich ketones.

Several Mannich ketones of 2-arylmethylenecycloalkanones were synthesised using the classical acid-catalysed Mannich reaction. Antibacterial activity of these new water-soluble compounds was reported against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus saprophyticus, Micrococcus luteus and Bacillus subtilis standard strains. Human cell line cytotoxicity of our new compounds was evaluated against HeLa cell lines. Some compounds showed low cytotoxicity (41.52 nM mL(-1) for 14 and 46.60 nM mL(-1) for 18) and proved to be efficient antibacterial agents against the Gram-positive strains. Minimum inhibitory concentrations varied from 1.56 to 100 microg mL(-1). The mechanism of action was examined, too.

Bacillus subtilis↗
PubMed2001

[Radiotherapy of childhood brain stem tumours]

STUDY OBJECTIVE: Description and evaluation of radiotherapy of inoperable brain stem tumours. Possibilities of improving therapeutic results. MATERIALS AND METHODS: Between 1987 and 2000 43 patients (23 boys and 20 girls, mean age 8.5+/-4.4 years) with brain stem tumours were treated with 6 MV and 9 MV X-ray. The doses administered ranged from 30 to 66 Gy; mean 50.41+/-7.67 Gy. Treatment in each case was performed according to CT- and /or MR-based radiotherapy plan. Since 2000 3D conformal radiotherapy plans have been prepared by using image fusion. RESULTS: All patients were followed. The mean follow-up period was 19.4 months (range: 1 to 112 months). For survival statistics the 2 to 3-year overall and symptom-free survivals were taken into account, the former ones in the function of tumour localisations. The gender of children did not affect the survival (p>0.74). No significant difference was found as to survival in the function of tumour localisation either (p>0.87). CONCLUSION: According to the literature data the results expected were not achieved by hyperfractionation and by delivering an overall focal dose of 72 to 78 Gy. Results can be improved by precise patient fixation and the routine application of 3D conformal radiotherapy plans prepared by CT- and MR-based image fusion. These together can result the correctly reproducible patient fixation, the homogenous radiation delivery in the target volume and the reduction of injury in the surrounding tissues. Irradiation should be performed also in histologically not verified tumours since a 24.6 month transitory improvement could be achieved in 60.5% of our patients.

Journal Article↗
PubMed2001

Theta synchronization in the limbic system: the role of Gudden's tegmental nuclei.

Theta rhythm is most prominent in the hippocampus but has also been recorded in other cortical and limbic structures and can play an important role in functional coupling of widely separated structures responsible for different components of the memory building process. Here we demonstrate in the rat that neuronal activity exhibiting strong state-dependent synchrony with rhythmic hippocampal electroencephalogram is present also at the brainstem level, specifically in the relatively small tegmental nuclei of Gudden intimately connected with the limbic forebrain. We found that during theta states, either occurring spontaneously or triggered by sensory stimulation in the urethane anaesthetized rat, all neurons in the anterior and ventral tegmental nuclei exhibited a consistent switch from irregular discharges to rhythmic bursts. The switch between these patterns closely matched the analogous transformations in the hippocampal EEG, but the level of synchrony between the two signals varied depending on the level of theta activation. During sensory stimulation, when theta is faster and more regular, the rhythmic bursts in the tegmentum showed extremely high coherence (up to 0.96) with hippocampal field potentials. During spontaneous theta, the average coherence was lower but still highly significant (0.62). Gudden's nuclei are reciprocally connected to the mammillary body complex (MB) occupying a strategic position at the gateway of hippocampofugal connections organized in the Papez circuit. Thus, coupling between the MB-Gudden circuit and the hippocampus and consequently the neuronal traffic through the Papez circuit and hence the assembly of limbic structures connected to the hippocampus may vary according to the activity in these specific brainstem nuclei.

Animals↗
PubMed2001

[Significant change in the number of appendectomies performed in Hungary during the last four decades].

The number of appendectomies carried out annually in Hungary diminished significantly during the last four decades till middle of nineties. From 1995 the annually number of appendectomies is hardly higher than a quarter of the number of operations in 1961. The reasons of this situation may be the improvement of diagnostic of appendicitis, as well as the rarer occurrence of this disease. In the changes of incidence of appendicitis the anti-bacterial treatments carried out in different reasons may be important factors. These treatments can change in composition of normal bowel bacterial flora. At the same time, when the number of appendectomies is diminishing the number of chronic bowel inflammations (e.g. Crohn disease, colitis ulcerosa) is increasing, this situation may be different sides of the same process.

Appendectomy↗
PubMed2001

Postoperative radiotherapy of childhood medulloblastomas.

The purpose of this work is to review the result of radiotherapy in the treatment of medulloblastoma in pediatric patients. Between 1986 and 1998, 66 children (45 boys and 21 girls) received postoperative irradiation in our institute. Their mean age was 8.29 years. Irradiation was performed by linear accelerator, 36 Gy were applied in the high risk group (partial tumor resection, tumor cell positivity in the liquor, metastases within the central nervous system) and 30 Gy in the low risk group (total tumor resection, negative liquor cytology, no metastases within the central nervous system) on the entire cerebrum and spinal cord. This was followed in both groups by the application of 20-20 Gy boost irradiation on the posterior scala. Studying the survival it has been found that the surgical radicality did not significantly influence the survival chances of patients, however, with the increase in the tumor size the survival chance significantly decreases (p = 0.03). When predicting life expectancy, however, the stage of tumor, the age of patients, the risk group and the M stage yielded essential information. At the age of 8 years and less, the rate of survivors is 67.6%, for those over 8 years is 75.9% (p = 0.21), however the younger age was not significant. The appearance of metastases considerably deteriorates the chances of survival (from 81.5% to 66.7%, p = 0.02). In the low risk group of patients the 5-year survival is 80%, while in the high risk group it is significantly lower, 67.4% (p = 0.04).

Adolescent↗
PubMed2000

Lateral tegmental field neurons with activity correlated to the 10-Hz rhythm in sympathetic nerve discharge.

Neurons in the lateral tegmental field (FTL) has been previously reported to have activity only minimally correlated (< 1% of neurons tested) with the 10-Hz rhythm of the slow wave of the sympathetic nerve discharge. We report here that 10% of the neurons recently tested in the FTL could be shown to correlate with the 10-Hz rhythm. The neuron-to-nerve coherence is weaker than in other medullary areas, but is nonetheless significant.

Animals↗
PubMed2000

Capillary electrophoretic analysis of wild type and mutant Proteus penneri outer membrane proteins.

In this study the virulence factors, outer membrane proteins (OMP), lipopolysaccharides (LPS), hemolysin, and the in vivo and in vitro virulence of wild-type Proteus penneri 357 and its two isogenic mutant variants--a transposon and a spontaneous mutant--were examined. The OMPs of these variants were analyzed by a new and fast technique, "dynamic sieving" capillary electrophoresis (CE). The OMP profiles were dominated by two peaks (39 and 43 kDa). In the P. penneri clone examined, both the transposon and the spontaneous mutations induced significant changes in the OMP patterns (in the relative percentage of the dominant proteins). CE was suitable for the comparative analysis of bacterial protein patterns in the genetic variants of this strain, and provided valuable results in connection with the bacteriological virulence. The LPS composition of the genetic variants also showed alterations. The wild type of P. penneri 357 showed a typical ladder pattern, an "S" form, and the mutants possessed "R" LPS patterns (only few bands) in the gels. In the bacteriological virulence tests the wild type of P. penneri 357 was virulent in the in vivo, and toxic in the in vitro assays, while both mutants showed neither toxicity nor pathogenicity.

Bacterial Outer Membrane Proteins↗
PubMed2000

Comparison of blocking agents for an ELISA for LPS.

ELISA is a sensitive, specific, reproducible and fast method for detection of antigen-antibody reactions. In case of non-protein antigens as LPS, problems exist, such as poor proportion of coating to microplates, non-specific binding of antibodies to the plastic wells. These problems were resolved partially by Takahashi and co-workers using poly-L-lysine for coating of LPS antigens. To reduce non-specific binding, blocking agent, such as bovine serum albumin (BSA) or casein is commonly used. We have to choose the blocking agent carefully because LPS can bind proteins non-specifically. This process can inhibit binding of LPS-specific antibody to LPS and decrease the sensitivity of method. In this paper we describe an ELISA test for LPS in which normal goat serum is used for blocking. This modification increases the sensitivity of ELISA. This method is useful for detection of LPS (S, R form) and anti-LPS antibody reaction in serological cross-reaction studies.

Blood Proteins↗
PubMed2000

[Local antibiotic treatment of chronic thoracic empyema].

The authors present their indications, aims and method for the local antibiotic treatment of chronic empyema thoracis. They analyse the sensitivity and resistant conditions of the most often occurring bacteria, Pseudomonas spp., in an open window treatment of empyema thoracis. 338 patients were treated for intrathoracic suppuration between January 1, 1987 and December 31, 1998. The youngest patient was 13, the oldest one was 90 (the average age was 53.2. Of these 11 died, representing a mortality rate of 3.2%. Of these 11 patients, 7 suffered from chronic intrathoracal suppuration. 82 patients had chronic empyema. 44 patients (13%) were treated by the open window procedure, 6 females and 38 males. The average age was 62.1. Of them 7 died, the mortality rate of chronic empyema thoracis was 8.5% in our department. Of 164 pus samples taken from suppurative pleura cavity bacteria, Pseudomonas spp., were bred in 148 cases during bacteriological examinations. Their bacteriological examinations confirm that local and aimed treatment by Polimyxin, Amikacin, Meronpenem, Ceftadizim, Imipenem, Tobramycin, Ciprofloxacin and Piperacillin proved to be the better medicine against Pseudomonas infection.

Administration, Topical↗