Dopamine D4 Receptor Agonist Drastically Increases Delta Activity in the Thalamic Nucleus Reuniens: Potential Role in Communication between Prefrontal Cortex and Hippocampus

Network oscillations are essential for all cognitive functions. Oscillatory deficits are well established in psychiatric diseases and are recapitulated in animal models. They are significantly and specifically affected by pharmacological interventions using psychoactive compounds. Dopamine D4 receptor (D4R) activation was shown to enhance gamma rhythm in freely moving rats and to specifically affect slow delta and theta oscillations in the urethane-anesthetized rat model. The goal of this study was to test the effect of D4R activation on slow network oscillations at delta and theta frequencies during wake states, potentially supporting enhanced functional connectivity during dopamine-induced attention and cognitive processing. Network activity was recorded in the prefrontal cortex (PFC), hippocampus (HC) and nucleus reuniens (RE) in control conditions and after injecting the D4R agonist A-412997 (3 and 5 mg/kg; systemic administration). We found that A-412997 elicited a lasting (~40 min) wake state and drastically enhanced narrow-band delta oscillations in the PFC and RE in a dose-dependent manner. It also preferentially enhanced delta synchrony over theta coupling within the PFC-RE-HC circuit, strongly strengthening PFC-RE coupling. Thus, our findings indicate that the D4R may contribute to cognitive processes, at least in part, through acting on wake delta oscillations and that the RE, providing an essential link between the PFC and HC, plays a prominent role in this mechanism.

Hierarchical Black Hole Mergers in Active Galactic Nuclei

The origins of the stellar-mass black hole mergers discovered by LIGO/Virgo are still unknown. Here we show that if migration traps develop in the accretion disks of active galactic nuclei (AGNs) and promote the mergers of their captive black holes, the majority of black holes within disks will undergo hierarchical mergers-with one of the black holes being the remnant of a previous merger. 40% of AGN-assisted mergers detected by LIGO/Virgo will include a black hole with mass ≳50M_{⊙}, the mass limit from stellar core collapse. Hierarchical mergers at traps in AGNs will exhibit black hole spins (anti)aligned with the binary's orbital axis, a distinct property from other hierarchical channels. Our results suggest, although not definitively (with odds ratio of ∼1), that LIGO's heaviest merger so far, GW170729, could have originated from this channel.

Zabofloxacin for chronic bronchitis

Treatment of lower respiratory tract infection poses as an ongoing challenge among respiratory tract diseases. Bacterial infections are causes of acute exacerbations in chronic bronchitis and indications for antibacterial therapy. Several antibiotics were applied to treat bacterial infections in chronic bronchitis, among them fluoroquinolones are considered potent, broad-spectrum agents with excellent tissue penetration. This monograph focuses on zabofloxacin, a novel fluoroquinolone agent recently approved and launched in South Korea, and summarizes the drug's antibacterial efficacy, pharmacokinetic properties and toxicity. Recent advances concerning fluoroquinolones in chronic bronchitis will be discussed, along with a comparison between zabofloxacin and moxifloxacin. Zabofloxacin has proved to be noninferior to moxifloxacin against major community-acquired Gram-positive and Gram-negative respiratory tract pathogens and found to be well tolerated in both oral and parenteral administrations. These features can make it a potential antimicrobial agent in therapy of chronic bronchitis and other lower respiratory tract infections.

Theta-rhythmic drive between medial septum and hippocampus in slow-wave sleep and microarousal: a Granger causality analysis

Medial septum (MS) plays a critical role in controlling the electrical activity of the hippocampus (HIPP). In particular, theta-rhythmic burst firing of MS neurons is thought to drive lasting HIPP theta oscillations in rats during waking motor activity and REM sleep. Less is known about MS-HIPP interactions in nontheta states such as non-REM sleep, in which HIPP theta oscillations are absent but theta-rhythmic burst firing in subsets of MS neurons is preserved. The present study used Granger causality (GC) to examine the interaction patterns between MS and HIPP in slow-wave sleep (SWS, a nontheta state) and during its short interruptions called microarousals (a transient theta state). We found that during SWS, while GC revealed a unidirectional MS→HIPP influence over a wide frequency band (2-12 Hz, maximum: ∼8 Hz), there was no theta peak in the hippocampal power spectra, indicating a lack of theta activity in HIPP. In contrast, during microarousals, theta peaks were seen in both MS and HIPP power spectra and were accompanied by bidirectional GC with MS→HIPP and HIPP→MS theta drives being of equal magnitude. Thus GC in a nontheta state (SWS) vs. a theta state (microarousal) primarily differed in the level of HIPP→MS. The present findings suggest a modification of our understanding of the role of MS as the theta generator in two regards. First, a MS→HIPP theta drive does not necessarily induce theta field oscillations in the hippocampus, as found in SWS. Second, HIPP theta oscillations entail bidirectional theta-rhythmic interactions between MS and HIPP.

Prevalence of plasmid-mediated quinolone resistance determinants in Enterobacteriaceae strains isolated in North-East Italy

We investigated the prevalence of plasmid-mediated quinolone resistance genes in 756 clinical isolates of Enterobacteriaceae originating from Microbiology Diagnostic Laboratories of North-East Italy. Five point zero two percent of isolates carried a qnr determinant while the aac(6')-Ib-cr determinant was detected in 9·25% of isolates. We also investigated the association between the plasmid-mediated quinolone resistance and the beta-lactamase genes, and characterized the plasmids carrying these determinants of resistance.

Interaction of concanavalin a with bacterial lipopolysaccharides in agarose gel

Binding of fluorescein isothiocyanate-labeled concanavalin A to a series of molecular species of lipopolysaccharide (LPS), purified from pathogenic bacteria, was studied via agarose gel precipitation experiments and the results were compared with available structural data.The LPS species could be divided into ConA-reactive and non-reactive ones. Reactivity resided in the O-specific chain of LPS, and binding to the lipid A or core moieties of LPS could not be demonstrated by the present methods. The α-D-glucose or α-D-mannose residues of the repeating O-specific oligosaccharide units appeared to be recognized by ConA, except when blocked by steric hindrance. Specificity of the reaction was verified by inhibition with 2% D-glucose. Binding by bacterium-specific sugar-residues could not be demonstrated.For precipitation to occur, polyvalency was required both for LPS and ConA, and the resulting precipitation appeared to be promoted by hydrophobic interactions between the lipid A moieties of LPS molecules. The LPS species were differently retained by the agarose gel, which can be explained by differences in their micellar structure in aqueous solution. E. coli O83 LPS did not readily diffused in 1% agarose gel, but its precipitation with ConA could be demonstrated either at elevated temperature or mixing it previously with molten agarose (Mancini's arrangement).

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

All-sky LIGO search for periodic gravitational waves in the early fifth-science-run data

We report on an all-sky search with the LIGO detectors for periodic gravitational waves in the frequency range 50-1100 Hz and with the frequency's time derivative in the range -5 x 10{-9}-0 Hz s{-1}. Data from the first eight months of the fifth LIGO science run (S5) have been used in this search, which is based on a semicoherent method (PowerFlux) of summing strain power. Observing no evidence of periodic gravitational radiation, we report 95% confidence-level upper limits on radiation emitted by any unknown isolated rotating neutron stars within the search range. Strain limits below 10{-24} are obtained over a 200-Hz band, and the sensitivity improvement over previous searches increases the spatial volume sampled by an average factor of about 100 over the entire search band. For a neutron star with nominal equatorial ellipticity of 10{-6}, the search is sensitive to distances as great as 500 pc.

Modulation of hippocampal theta oscillation by histamine H3 receptors

Preclinical findings demonstrate procognitive actions of histamine 3 (H3) receptor antagonists/inverse agonists. Since a prominent role of neuronal network oscillations of the hippocampus, such as theta band oscillation, has been recognized in numerous cognitive functions, in the present study, the potential involvement of H3 receptors in modulation of hippocampal theta activity has been investigated using various recording paradigms. Systemic administration of the selective H3 receptor antagonists/inverse agonists, thioperamide and ciproxifan (0.1 mg/kg to 1 mg/kg i.v.), dose dependently increased hippocampal theta power, similarly to methylphenidate (0.1-1 mg/kg i.v.), in chloral hydrate anesthetized rats. When hippocampal theta oscillation was elicited by electrical brainstem (nucleus pontis oralis) stimulation, ciproxifan (1 mg/kg i.v.) augmented the power of stimulation-induced theta. In contrast, systemic administration of methylphenidate (1 mg/kg i.v.) did not modify elicited theta. To analyze the role of H3 receptors on stage- and behavior-dependent hippocampal theta activity, polysomnographic recordings were carried out together with field potential recordings at the hippocampal fissure in freely moving rats for 8 h during the light phase of the circadian cycle. Systemic administration of ciproxifan (3.0 mg/kg, i.p.) promoted wakefulness with a concomitant reduction in cortical delta power and augmented novelty-induced hippocampal theta activity. These findings provide evidence that H3 receptors play an important role in regulation of hippocampal theta oscillation, representing one of the probable mechanisms involved in histamine-induced modulation of higher brain functions, such as attention and learning.

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.

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.

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.

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.

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.

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.

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).

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.

[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.

[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.

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.

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.

[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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

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.

Induction of Release of Tumor Necrosis Factor and IL-6from Human Mononuclear Cells byBacteroidesstrains

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.

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.