Biomedical subjects

B Kocsis

Publications and source records attributed to B Kocsis.

At least 37 records · Page 2Linked to original sources

PubMed1999

2-Substituted indazoles. Synthesis and antimicrobial activity.

2-Isothiocarbamoyl substituted fused pyrazolines and their S-alkyl derivatives were prepared as potentially antimicrobial agents. Conventional methods were used to synthesize the novel derivatives starting from cyclic unsaturated ketones and thiosemicarbazide under acidic catalyst. These cyclizations yielded only one diastereoisomer of 3-H, 3a-H cis. The alkylations were performed applying alkyl halides. The structures of the new compounds, including configurations and conformations, were elucidated by NMR spectroscopy, also making use of 2D-HSC, DEPT and DNOE measurements. The S-alkyl derivatives were evaluated for activity against Gram-negative and Gram-positive bacteria and their in vitro toxicity was determined on HeLa cells. The structure-activity relationship was also studied.

Journal Article↗

PubMed1999

Interdependence of multiple theta generators in the hippocampus: a partial coherence analysis.

The extracellularly recorded theta oscillation reflects a dynamic interaction of various synaptic and cellular mechanisms. Because the spatially overlapping dipoles responsible for the generation of theta field oscillation may represent different mechanisms, their separation might provide clues with regard to their origin and significance. We used a novel approach, partial coherence analysis, to reveal the various components of the theta rhythm and the relationship among its generators. Hippocampal field activity was recorded by a 16-site silicon probe in the CA1-dentate gyrus axis of the awake rat. Field patterns, recorded from various intrahippocampal or entorhinal cortex sites, were used to remove activity caused by a common source by the partialization procedure. The findings revealed highly coherent coupling between theta signals recorded (1) from the hippocampal fissure and stratum (str.) oriens of the CA1 region and (2) between CA1 stratum radiatum and the dentate molecular layer. The results of partial coherence analysis indicated that rhythmic input from the entorhinal cortex explained theta coherence between signals recorded from the hippocampal fissure and str. oriens but not the coherence between signals derived from str. radiatum and the dentate molecular layer. After bilateral lesions of the entorhinal cortex, all signals recorded from both below and above the CA1 hippocampal pyramidal cell layer became highly coherent. These observations indicate the presence of two, relatively independent, theta generators in the hippocampus, which are mediated by the entorhinal cortex and the CA3-mossy cell recurrent circuitry, respectively. The CA3-mossy cell theta generator is partially suppressed by the dentate gyrus interneuronal output in the intact brain. We suggest that timing of the action potentials of pyramidal cells during the theta cycle is determined by the cooperation between the active CA3 neurons and the entorhinal input.

Action Potentials↗

PubMed1999

Medium-frequency oscillations dominate the inspiratory nerve discharge of anesthetized newborn rats.

In this study we examined the synchronization of the discharge of phrenic and recurrent laryngeal motoneurons in anesthetized rat pups 14 to 36 days of age and kittens, 14-15 days old. We found that the inspiratory nerve activity consisted of synchronized bursts separated by 20-35 ms, corresponding to medium-frequency oscillations (MFO). Accordingly, the autospectra of the neurograms had two peaks, one at the respiratory rate and the other between 22. 8-43.0 Hz. No significant coherence was found between MFOs in the discharges of different nerves. High-frequency oscillations (HFO) characteristic for the adult inspiratory nerve activity were not present in the newborn rats. These findings demonstrate that phrenic nerve discharge of rat pups, like that of kittens and piglets, is in the MFO range, and suggest that MFO activity is an index of an early developmental stage of the respiratory system.

Adjuvants, Anesthesia↗

PubMed1999

Cardiac- and noncardiac-related coherence between sympathetic drives to muscles of different human limbs.

Partial coherence analysis was used to evaluate the extent to which coherence between resting muscle sympathetic activity (MSA) in different pairs of limbs in humans is explained by the common baroreceptor input and by other noncardiac-related factors. Multiunit MSA in two or three nerves, arterial blood pressure, and electrocardiogram were recorded simultaneously. Correlated MSA consisted of a sharp periodic component at the heart rate and a wideband component of relatively low power distributed between 0 and 2-2.5 Hz. Quantitative analysis revealed stronger coupling between MSAs in close limbs than in distant limbs (peak coherence leg-leg, 0. 94 +/- 0.03; arm-leg, 0.76 +/- 0.11). Furthermore, the wideband component, unaffected by partialization with circulatory signals, was significantly stronger between leg-leg (0.67 +/- 0.10) than between arm-leg pairs (0.29 +/- 0.10), i.e., noncardiac-related components explained 71% of leg-leg and 38% of arm-leg coherences at the frequency of the heart. Our results indicate that nonuniform relationship exists between resting sympathetic outflow to muscles in close and distant extremities which is, however, partially masked by the effect of the common rhythmic baroreceptor input.

Adult↗

PubMed1999

Heart rate surges during REM sleep are associated with theta rhythm and PGO activity in cats.

Rapid eye movement (REM) sleep is characterized by periods of profound cardiac autonomic activation evident in heart rate surges in humans and canines. Our goals were to determine whether or not the heart rate surge phenomenon occurs in cats and to characterize concurrent central nervous system activity. Cortical and hippocampal electroencephalogram, electromyogram, electrooculogram, pontogeniculooccipital (PGO) waves, subcutaneous electrocardiogram, and respiration were recorded. Bouts of sinus tachycardia lasting >/=3.5 s achieved a rate of 210 beats/min and were present predominantly during REM sleep. Heart rate during the surges rose an average of 26.4% from 132.5 +/- 2.0 beats/min before the surge to 167.5 +/- 2.6 beats/min (P < 0.001) and returned to 130.7 +/- 2.6 beats/min (P < 0.001). The heart rate surges were invariably accompanied by increased incidence and frequency of hippocampal theta waves and increased PGO wave frequency and incidence of PGO wave clusters and eye movement clusters. The occurrence of surges was dramatically reduced from 0.11 +/- 0.03 to 0.01 +/- 0.01/15 s of REM sleep (P = 0.02) by atenolol (0.6 mg/kg iv), indicating that the phenomenon is beta(1)-adrenergically mediated. These findings suggest a coupling between central activation of cardiac sympathetic nerves and the generation of hippocampal theta waves and PGO activity.

Animals↗

PubMed1998

Spinal cord segments mediating tonic sympathetic nerve discharge to the kidney in the anesthetized cat.

According to anatomical data, preganglionic neurons projecting to the kidney via sympathetic ganglia occupy a wide range of adjacent segments in the thoracolumbar spinal cord, from Th7 to L2. Since, however, the majority of preganglionic neurons is silent at resting states, the active segments indeed transmitting sympathetic activity, at rest, may be different. In the present experiments, the spontaneous sympathetic activity was recorded before and after the sympathetic trunk and white rami (WR) Th8-L3 were cut in a sequential manner. The step-by-step changes in the power of renal nerve discharge were estimated and used for mapping tonic renal outflow to the spinal cord. We found that powerful activity comprising 70-95% of the power of control recordings remained after eliminating the input from Th1-Th12, indicating that thoracic spinal cord including segments that contain the largest number of cells projecting to renal postganglionic neurons contributes relatively weakly to tonic renal nerve activity. It appeared that resting sympathetic nerve discharge was predominantly maintained by the caudalmost division of the renal preganglionic neuron population since the largest decrease in nerve power occurred after severing WR Th13, L1, and L2. These findings suggest that the 'active segmental map' of preganglionic neurons controlling a certain organ at rest does not necessarily match the distribution of the total population of neurons projecting to the same effector.

Animals↗

PubMed1998

[Recurrent significant bacteriuria and progression of IgA nephropathy].

Tubulointerstitial changes seems to be of decisive importance among factors influencing the prognosis of IgA nephropathy. In consequence of decreased protection ability of mucous membranes, in some cases masked urinary tract infections may stand in the background of the tubulointerstitial changes. In this study the connection between urinary tract infections, significant bacteriurias and the progression of IgA nephropathy was retrospectively investigated. The data and the progress of the disease of 19 IgA nephropathy patients with significant bacteriuria (microbiologically identified) were compared to 19 IgA nephropathy patients of similar age, sex and the time of follow-up without bacteriuria. During the follow-up (on the average 8.5 years), the renal function (values of serum creatinine) decreased significantly (p < 0.05) in both groups, but there was no significant difference between the two groups. Neither at start, nor at the end of the follow-up no significant difference was found in the two groups in the prevalence of proteinuria, haematuria, hypertension and between the values of serum parameters. On the basis of these data we assume, that with the help of frequent medical check up and adequate antibiotic treatment the unfavourable effects of urinary tract infections (chronic tubulointerstitial changes) can probably be fended off.

Adult↗

PubMed1998

Protein profile characterization of bacterial lysates by capillary electrophoresis.

A fast and reproducible method was developed to characterize cell lysates by their electrophoretic profiles using capillary electrophoresis (CE). Characteristic and reproducible patterns were recorded for each bacterial strains when "dynamic sieving" CE, using a polymer solution in the capillary, was applied to distinguish four strains of the Enterobacteriaceae family. The electropherograms showed distinct differences when comparing them to the sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) protein profiles. This is certainly a result of the differences in the separation principles and in the detection methods of the two techniques.

Bacterial Proteins↗

PubMed1998

Changes in outer membrane protein profiles of bacteria after meropenem-induced postantibiotic effect studied by capillary electrophoresis.

Persistent inhibition of bacterial growth, called postantibiotic effect (PAE), after a short exposure to a new carbapenem, meropenem, was determined in different strains of the Enterobacteriaceae family. Capillary electrophoresis (CE), as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to study the outer membrane protein (OMP) profiles before and after meropenem treatment. CE proved to be suitable for the characterization of the OMP profiles of bacteria. Significant changes in the electrophoretic patterns were observed, showing the consequential effect of meropenem on bacteria.

Bacterial Outer Membrane Proteins↗

PubMed1998

Induction of release of tumor necrosis factor and IL-6 from human mononuclear cells by Bacteroides strains.

The role of anaerobic Gram-negative bacteria in inducing cytokines during mixed infections involving aerobic and anaerobic bacteria is relatively poorly defined. The purpose of this study was to establish whether or not intact Bacteroides fragilis and related species, isolated from severe infections and from the faeces of healthy persons are capable of releasing tumor necrosis factor (TNF) and IL-6 from human mononuclear cells and whole blood. The purified lipopolysaccharides of Bacteroides fragilis strain (No. 7), extracted by the aqueous phenol method from BHI cultures and from BHI culture supplemented with 5% horse serum, were also tested. TNF release was detected by the WEHI 164-dependent bioassay and IL-6 production by the B-9 cell-dependent bioassay. Heat-inactivated Bacteroides strains belonging to different species were able to induce TNF (1x10(1)-5x10(2) U/mL) and IL-6 (1x10(1)-5x10(5) pg/mL) release from human mononuclear cells. When whole blood was used, the production of TNF and IL-6 was more pronounced (very probably because of the presence of certain serum factors). The culturing conditions (the presence of 5% horse serum in the BHI broth) influenced the inducing activity of almost all strains tested. The isolated lipopolysaccharide of Bacteroides fragilis strain No. 7 proved to have a rough profile on PAGE. There were no differences in TNF and IL-6 induction when the lipopolysaccharides of the strain was cultured in BHI or in BHI supplemented with 5% horse serum. Bacteroides strains often outnumber Enterobacteriaceae in the faeces and in mixed infections, and their role in inducing and/or modulating the host response in septic shock should not be overlooked.

Journal Article↗

PubMed1998

Contiguous pattern spreading in patients with Hodgkin's disease.

BACKGROUND: In 1966, Rosenberg and Kaplan hypothesized that Hodgkin's disease (HD) arises at a discrete primary site and subsequently spreads in a predictable manner via functionally contiguous lymph nodes. However, their results were not statistically evident. It was our aim to describe the spreading in the lymphatic system more precisely and to confirm their postulate. METHODS: Between 1971 and 1992, 297 patients underwent pathological staging for HD. Our subsequent evaluation was restricted to the 236 cases with cervical involvement (65 bilateral, 80 dextral and 91 sinistral), those with lymph nodes on the right side (65 + 80 = 145) being analyzed separately from those with tumours on the left (65 + 91 = 156). Spreading via the lymphatic system was assessed by scoring of the number of involved and uninvolved nodes in six regions, which are functionally contiguous in the lymph system but not necessarily anatomically neighboured. The number of 'gaps' (i.e. missed nodes) observed according to a systematic spreading model was compared with that expected (probability model) if a random course had been followed. RESULTS: Of the 156 patients with left cervical HD, 117 (75%) had para-aortic or spleen involvement, 90 (58%) had mediastinal involvement, 65 (42%) had right cervical involvement, 50 (32%) had axillary involvement and 23 (15%) had inguinal involvement. Of the 145 patients with right cervical HD, 112 (77%) had mediastinal involvement, 89 (61%) had para-aortic or spleen involvement, 65 (44%) had left cervical involvement, 44 (30%) had axillary involvement and 16 (11%) had inguinal involvement. In patients with left or right cervical lymph nodes, the proportions observed with gaps in the spreading were 37 and 27% (SE 7%), respectively, whereas the corresponding values of gaps expected in a probability model if a random course of spreading had been followed would have been 84 and 73% (P = 0.0001 and 0.0001, respectively). CONCLUSION: Our data support the concept that HD spreads in a predictable manner via functionally contiguous lymph nodes. In patients with right cervical lymph nodes, HD spreads via the upper mediastinum and pulmonary hila to the upper abdominal nodes and the spleen. In those with left cervical tumours, HD spreads directly to the abdomen (bypassing the mediastinum), then upward again via the pulmonary hila and upper mediastinum to the neck region (bilateral involvement) and from here it proceeds to the axillary nodes. Finally the inguinal nodes are involved.

Adult↗

PubMed1998

Reduction of the extracellular level of glutamate in the median raphe nucleus associated with hippocampal theta activity in the anaesthetized rat.

The relationship between hippocampal activity and the extracellular level of excitatory amino acids in the median raphe nucleus has been studied in urethane anaesthetized rats, using the in vivo microdialysis technique. Dialysates were collected from the median raphe nucleus during two to eight sampling periods of equal length (20 min) and hippocampal electroencephalogram was continuously monitored. For each observation period, the average glutamate level in the median raphe nucleus was determined and the percentage of theta and non-theta segments in the hippocampal recordings was calculated. Theta synchronization, in these experiments, either developed spontaneously or it was elicited by injection of anticholinesterase (Physostigmine or Sintostigmine, i.p.) or by a series of short tail pinches. The relationship between hippocampal activity and glutamate release in the median raphe nucleus was characterized by comparison of the direction of changes in these two parameters in consecutive sampling periods. We found that as long as theta/non-theta ratio changed spontaneously or under the effect of anticholinesterase (n = 7), the extracellular level of glutamate in the median raphe nucleus was elevated during periods dominated by desynchronized hippocampal activity as compared with those mostly containing long and/or frequently occurring theta segments. Such relationship was not observed in the adjacent reticular formation (n = 4) and in the median raphe nucleus during sensory stimulation (n = 2). The present data complete those found earlier indicating that the desynchronizing serotonergic influence originating from the brainstem is maintained by a tonic excitatory input to the median raphe nucleus. Since the majority of glutamatergic afferents to the median raphe nucleus originates from the lateral habenula and the interpeduncular nucleus, known to connect limbic forebrain to the brainstem, theta associated changes in median raphe nucleus glutamate levels might reflect descending forebrain influences, suggesting therefore a feedback regulation of the hippocampal activity involving brainstem structures.

Animals↗

PubMed1998

Spinal segments communicating resting sympathetic activity to postganglionic nerves of the stellate ganglion.

It has been shown earlier using sympathetic reflexes and anatomic techniques that preganglionic neurons controlling different effectors occupy wide and overlapping ranges of adjacent segments in the spinal cord (cardiac: T1-T7, vertebral: T2-T8). Because, however, the majority of preganglionic neurons are silent at resting states, the present study was designed to estimate the segmental map of subsets of these neurons including only those active at rest using simultaneous recordings from the inferior cardiac and vertebral nerves, under chloralose-urethan or urethan anesthesia. In 22 cats, thoracic white rami T1-T8 were cut in a sequential manner. Three-minute-long data segments were recorded between sectionings and analyzed in the frequency domain using the fast Fourier transform. We found that cardiac and vertebral active maps involved segments T3-T5 and T4-T8, respectively. In individual experiments, however, most of the power of rhythmic activity originated from only one or two segments and the dominant segments for the two nerves never overlapped. Moreover, the separation between dominant segments generating cardiac and vertebral nerve discharges was wider and the distribution of tonically active preganglionic neurons projecting to each nerve was narrower under urethan than chloralose-urethan anesthesia. We conclude that the proportion of active to quiescent preganglionic neurons regulating cardiac and vertebral nerve discharges varies from spinal segment to segment and that active neurons projecting to these nerves are nonoverlapping.

Animals↗

PubMed1998

Serologic examinations in acute appendicitis.

Authors studied the formation of endotoxic antibody level in healthy adults and in patients with appendicitis with a technique (indirect haemagglutination) not used till now. They found the antibody level against endotoxin to be increased in 91% of their patients in the postoperative period. Decrease in the antibody level against endotoxin was observed in two patients with gangrenous appendicitis and two patients with perforated appendicitis. Summarizing their results, authors consider mixed (aerobic, anaerobic) infection to be of decisive importance in the development of acute appendicitis, contributing to the weakened immune response of the host.

Acute Disease↗

PubMed1997

Neurons of the rostral para-ambiguual field have activity correlated to the 10-Hz rhythm in sympathetic nerve discharge of urethane-anesthetized cat.

Using the techniques of time domain correlation (mid-signal spike-triggered averaging) and frequency domain correlation (neuron-to-nerve coherence), 24% (54) of a sample of 229 neurons of the rostral para-ambiguual field have shown to have activity correlated to the 8- to 13-Hz rhythm in the inferior cardiac sympathetic nerve discharge (SND) of urethane-anesthetized cat. This correlation existed in both baroreceptor-innervated and -denervated animals. Of the correlated neurons, 37% (20) were non-rhythmically firing and displayed flat autospectra, while 63% (34) fired rhythmically and contained well-defined peaks in their autospectra. The group firing rate of these neurons was 4.3 +/- 0.4 spikes/s, indicating that they are not pacemaker neurons for the 10-Hz SND rhythm. The group time of firing of these neurons to the next peak of the SND slow wave was 52 +/- 4 ms. Correlation of the activity of medullary neurons with the 8-13-Hz rhythm of the SND was previously claimed only for rostral ventrolateral medulla, caudal raphe, and rostral caudal ventrolateral medulla. This present finding suggests that this behavior may be more widely spread throughout the medulla.

Anesthetics, Intravenous↗

PubMed1997

Power spectral analysis of inspiratory nerve activity in the anesthetized rat: uncorrelated fast oscillations in different inspiratory nerves.

The spectral composition of the inspiratory nerve discharge was studied in spontaneously breathing Sprague-Dawley rats under urethane (n = 7) or barbiturate (n = 10). Left phrenic nerve activity was recorded simultaneously with right phrenic or left recurrent laryngeal nerves. We found that all neurograms showed prominent fast oscillators at common frequencies in the high frequency (HFO) range. Concurrent medium frequency oscillations (MFO) were present in inspiratory nerve discharges of four rats anesthetized with Nembutal. Significant coherences between nerves were uncommon (n = 2) and were only found between HFOs. Thus although nerve autospectra were dominated by HFO, weak correlations indicated a relatively weak system HFO in th central pattern generator, in the anesthetized rat.

Anesthesia↗

PubMed1997

Phase relations of rhythmic neuronal firing in the supramammillary nucleus and mammillary body to the hippocampal theta activity in urethane anesthetized rats.

Structures in the caudal diencephalon including the posterior hypothalamic nucleus, the supramammillary nucleus (SUM) and the nuclei of the mammillary body (MB) occupy a strategic position in the crossroads of ascending and descending traffic between the brainstem and the limbic forebrain (septum/hippocampus). In this study we analyzed the phase relations of rhythmically discharging SUM/MB cells to hippocampal theta rhythm in urethane anesthetized rats with a dual aim of separating different functional types of SUM and MB neurons and characterizing their coupling to septohippocampal theta oscillators. We found that rhythmically firing neurons in the SUM/MB represent a functionally heterogenous population of cells that are coupled with forebrain theta oscillators at different preferred phases. Based on their phase relations to hippocampal theta four groups of rhythmic SUM/MB cells were identified. Neurons of the first and second groups fired out-of-phase relative to each other and synchronously with the positive (8 degrees +/- 7) or negative peaks (-177 degrees +/- 7) of theta field activity in the hippocampus, recorded above the CA1 pyramidal layer. Cells of the other two groups, also forming out-of-phase counter-parts, fired on the rising (97 degrees +/- 9) or falling segments (-97 degrees +/- 6) of CA1 theta waves. The peaks in the phase distribution histogram were well separated, and the empty zones between them were wider (40-70 degrees) than those comprising the phase data for different groups. The variations of phase values for individual neurons, when tested during several theta epochs, did not exceed the range of a single group. Theta field potentials were also recorded in the SUM/MB and were advanced by one quarter of the cycle (79 degrees +/- 9, range 56-99 degrees) relative to CA1 theta oscillations. The present results indicate that, similar to other theta-generating structures, rhythmically firing neurons can be classified on the basis of their phase relations in the SUM/MB as well. Different classes of SUM/MB neurons might play different roles in generating and/or transmitting theta rhythmic activity of the limbic system.

Anesthetics, Intravenous↗

PubMed1997

Brainstem-diencephalo-septohippocampal systems controlling the theta rhythm of the hippocampus.

We present a new model for the generation of theta rhythm of the hippocampus. We propose that theta at CA1 involves extracellular current fluxes produced by alternating depolarizing and hyperpolarizing membrane potential fluctuations of large populations of hippocampal pyramidal cells. Pyramidal cells are, in turn, controlled by rhythmically bursting cholinergic and GABAergic cells of the medial septum/vertical limb of the diagonal band. We postulate that septal cholinergic and GABAergic rhythmically bursting cells fire in relative synchrony; their coordinated burst discharge (burst mode) drives the positive-going phase of intracellular theta and associated firing of pyramidal cells; their synchronized pauses (interburst mode) give rise to the negative-going phase of intracellular theta and an inhibition of pyramidal cells. We further demonstrate that the theta rhythm is controlled by a network of cells extending from the brainstem to the septum/hippocampus. During theta, tonically discharging cells of the nucleus reticularis pontis oralis activate neurons of the supramammillary nucleus; the supramammillary nucleus, in turn, converts this steady barrage into a rhythmical pattern of discharge which is relayed to GABAergic/ cholinergic rhythmically bursting cells of the medial septum. The septal rhythmically bursting cells modulate subsets of hippocampal interneurons and principal cells in the generation of the theta rhythm. We review evidence showing that the serotonin-containing neurons of the median raphe nucleus desynchronize the hippocampal electroencephalogram, presumably by disrupting the rhythmical discharge of septal cholinergic and GABAergic neurons. Finally, we summarize recent work indicating that the theta rhythm is critically involved in memory functions of the hippocampus and that its disruption (electroencephalographic desynchronization) may block or temporarily suspend mnemonic processes of the hippocampus.

Animals↗