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A Tóth

Publications and source records attributed to A Tóth.

At least 19 recordsLinked to original sources
PubMed2006

Periodic heterogeneity-driven resonance amplification in density fingering.

Periodic heterogeneity is introduced in experiments with thin solution layers where downward propagating planar autocatalytic fronts are hydrodynamically unstable and cellular patterns develop. The evolution of fingers is greatly affected by the spatial heterogeneity when the wave number associated with it falls in the vicinity of the most unstable mode of the reference system with uniform thickness. The imposed heterogeneity will drive the instability by amplifying the modes with the matching wave numbers as indicated by the experimentally constructed dispersion curves.

Journal Article↗
PubMed2005

Fatal suicide cases from 1991 to 2000 in Szeged, Hungary.

The aim of this study is to analyze the fatalities due to suicide in the period of 1991-2000. The autopsy reports of 719 suicide cases during that period of the Department of Forensic Medicine, University of Szeged were reviewed retrospectively. The victim's age, sex, way of commitment, place of death, the presence of alcohol and drug influence and survival time were recorded. Five hundred and one of the (69.6%) total 719 suicide fatalities were men and 218 (30.4%) were women. The largest age groups were 41-50 in men, in women we experienced a 'double-peak' of age groups 41-50 and 71-80. The most frequent way of committal was hanging (46%). The results revealed that 38.8% of the 474 victims whose blood and/or urine alcohol concentration measurement were carried out consumed alcohol prior to the act. The presence of licit drugs in 12% of not drug-related cases were experienced.

Adolescent↗
PubMed2005

Occurrence and regional distribution of SHV-type extended-spectrum beta-lactamases in Hungary.

In order to determine the presence and geographical distribution of SHV-type extended-spectrum beta-lactamase genes among Enterobacteriaceae strains in Hungary, isolates from 25 microbiology laboratories throughout the country were collected between January 2002 and August 2003 and examined. Sequencing of the genes showed that SHV-5 and SHV-2a are the dominant SHV-types in extended-spectrum beta-lactamase-producing Enterobacteriaceae strains in this country. The SHV-2 gene, which is prevalent in many European countries, was not detected, but one isolate carried the SHV-12 gene. The results show that these genes are circulating among Enterobacteriaceae strains in Hungary and indicate that strict infection control measures are warranted in order to prevent their spread.

Cross Infection↗
PubMed2003

Density fingering of an exothermic autocatalytic reaction.

Density fingering of exothermic autocatalytic fronts in vertically oriented porous media and Hele-Shaw cells is studied theoretically for chemical reactions where the solutal and thermal contribution to density changes have opposite signs. The competition between these two effects leads to thermal plumes for ascending fronts. The descending fronts behave strikingly differently as they can feature, for some values of the parameters, fingers of constant amplitude and wavelength. The differences between up and down going fronts are discussed in terms of dispersion curves and nonlinear dynamics. The theoretically predicted dispersion curves are experimentally evidenced with the chlorite-tetrathionate reaction.

Journal Article↗
PubMed2003

De novo tumors after kidney transplantation: the Budapest experience.

In a retrospective study we analyzed the incidence and characteristics of de novo tumors developing in renal transplant recipients treated in our center. The 5% incidence de novo tumors developing among patients treated with azathioprine and prednisolone (n = 241) was similar to the 5.4% incidence of de novo tumors developing among patients treated with calcineurin-based immunosuppression (n = 1918). The most common malignancies among our patients were basal cell (21.7%) and squamous cell (13.9%) carcinomas of the skin, followed by urogenital (10.4%) and lung malformations (9.6%). A high incidence of Kaposi's sarcoma (9.6%; half cutaneous and half visceral) and a lower than expected incidence of posttransplant lymphoproliferative disorder (PTLD; 3.5%) was found. Among patients developing de novo tumors, the incidence of death with a functioning graft was higher than among recipients without tumors. Moreover, the incidence of tumor-related death was high among the de novo tumor recipients. Among our recipients, the most aggressive tumors were Kaposi's sarcoma, lung tumors, lymphomas, and gastrointestinal tumors, which occurred relatively early after transplantation and were the cause of death in most cases. Compared to tumor registry data, we found an inverse basal-to-squamous cell carcinoma ratio, a lower incidence of PTLD, and a higher incidence of Kaposi's sarcoma.

Azathioprine↗
PubMed2002

Changes in brain activation caused by caloric stimulation in the case of cochleovestibular denervation--PET study.

There are a number of well-known stimulation methods for the investigation of the central projection of the vestibular system. In addition to optokinetic, galvanic and neck vibration tests, the most widespread method is caloric stimulation. These listed methods cause not only vestibular, but also other effects on the central nervous system (CNS) (acoustic, tactile and nociceptive). In this paper, positron emission tomography (PET) was used to investigate whether caloric stimulation contains a non-vestibular (extravestibular) component, which would cause a distortion in the cortical activity and therefore in the vestibular effect on the CNS. Caloric stimulation was carried out in six patients who had been operated on due to cerebello-pontine angle tumour. These patients suffered post-operatively from a complete lesion of the vestibular system and anacusis on the operated side. Ipsilaterally activated areas were the inferior pole of the post-central gyrus and temporoparietal junction, caudal part of the post-central gyrus (SI, SII), inferior parietal lobule and medial frontal gyrus. Contralaterally activated areas were the anterior cingulate gyrus, medial frontal gyrus, posterior part of the insula, post-central gyrus and temporoparietal junction (SII). Ipsilaterally deactivated areas were the caudal and cranial part of the medial occipital gyrus (V2, V3, V4, V5). Contralaterally deactivated areas were the lingual gyrus, inferior occipital gyrus (V2, V3) and fusiform gyrus. On the basis of these data, it was postulated that, during caloric stimulation, extravestibular reaction also occurs, which corresponds to the subjective feeling of heat and pain. The deactivation of the occipital cortex due to an extravestibular effect was demonstrated. This is the first observation to suggest the possibility of nociceptivevisual interaction.

Adult↗
PubMed2001

The application of cross-point switch arrays as input selector switch devices for multi-channel electrophysiological experiments.

Integrated circuits (ICs) containing cross-point switch arrays were applied to create analog input selector switch devices for multi-channel electrophysiological experiments. The described analog input selector switch devices make it possible to connect to the main amplifier's inputs those microelectrode and preamplifier output wires that yield unit discharges of acceptable shape and amplitude, or yield other kind of acceptable electrophysiological signals (EEG, EP). This kind of selector allows to use higher number of preamplifier channels and to ignore the input channels without adequate signals or the channels with noisy inputs. No manual switching is required, as the work is done by computer controlled switches. The switch positions can be saved and reloaded at the next experimental session through an I/O port (e.g. the parallel port) of the computer.

Amplifiers, Electronic↗
PubMed2001

Identification and structural analysis of synthetic oligosaccharides of Shigella sonnei using MALDI-TOF MS.

MALDI-TOF mass spectroscopy was used for the molecular weight determination of protected synthetic oligosaccharides related to a cell surface bacterial polysaccharide. By-products containing chlorinated protecting groups caused isotopic patterns characteristic of the natural isotopic distribution of chlorine, were identified on the basis of isotopic distribution. 2,4,6-Trihydroxyacetophenone (THAP) as a matrix was better than 2,5-dihydroxybenzoic acid (DHB) for compounds containing chlorine, since monoisotopic resolution and no fragmentation were observed. In the post source decay (PSD) mode the identification of the oligosaccharide sequence through cleavage of the interglycosidic linkages was also possible, thus providing a sensitive and accurate tool for the structural verification of synthetic oligosaccharide intermediates.

Carbohydrate Conformation↗
PubMed2001

Path finding by tube morphogenesis in an amoeboid organism.

We have studied how the plasmodium of Physarum polycephalum, a large amoeboid cell, is able to track the shortest path between two selected points in a labyrinth. When nutrients are supplied at these points to a sheet-like plasmodium extended fully in a maze, the organism forms a single tube which connects the two sites via the shortest route. During the path finding, plasmodial parts in dead ends of the maze shrink and finally the tube with the minimum-length is selected from the existing possibilities. A simple cellular mechanism based on interacting cellular rhythms may describe the experimental observations.

Animals↗
PubMed2001

A screen for genes required for meiosis and spore formation based on whole-genome expression.

BACKGROUND: Meiosis is the process by which gametes are generated with half the ploidy of somatic cells. This reduction is achieved by three major differences in chromosome behavior during meiosis as compared to mitosis: the production of chiasmata by recombination, the protection of centromere-proximal sister chromatid cohesion, and the monoorientation of sister kinetochores during meiosis I. Mistakes in any of these processes lead to chromosome missegregation. RESULTS: To identify genes involved in meiotic chromosome behavior in Saccharomyces cerevisiae, we deleted 301 open reading frames (ORFs) which are preferentially expressed in meiotic cells according to microarray gene expression data. To facilitate the detection of chromosome missegregation mutants, chromosome V of the parental strain was marked by GFP. Thirty-three ORFs were required for the formation of wild-type asci, eight of which were needed for proper chromosome segregation. One of these (MAM1) is essential for the monoorientation of sister kinetochores during meiosis I. Two genes (MND1 and MND2) are implicated in the recombination process and another two (SMA1 and SMA2) in prospore membrane formation. CONCLUSIONS: Reverse genetics using gene expression data is an effective method for identifying new genes involved in specific cellular processes.

Cell Nucleus↗
PubMed2001

[Qualitative and quantitative detection of hepatitis C virus RNA by PCR technique. Monitoring of viral copies after liver transplantation].

The authors demonstrate the HCV nucleic acid amplification method is not wide-spread in Hungary yet. The HCV-RNA is usually detectable 2-4 weeks after infection independently the immunostate of the patients. The authors help to select the adequate measurement(s) in logical order when HCV infection is suspected. The benefit of the PCR method is emphasized. Monitoring of the HCV-RNA titer of the liver transplanted patients promotes to establish the fluctuation of HCV-RNA copies and the effectivity of therapy following transplantation. The detection of HCV-RNA by PCR method is a proof of an acute or chronic infection and rules out past infection. The quantitative PCR measurement is useful for determination of indication and control of efficacy of antiviral therapy.

Adult↗
PubMed2001

[Rapid diagnostic method for detecting Down syndrome in newborns].

The authors analysed the applicability of FISH on buccal and peripheral blood smears to detect Down syndrome among newborn infants. 11 children with previous cytogenetic result and 15 neonates examined prospectively were included in the study. All FISH results were in accordance with the cytogenetic diagnosis. In the prospective group the status of Down syndrome was confirmed in 12 cases, while 3 neonates turned to be healthy. Based on their preliminary results the authors emphasize the technique is extremely useful for a quick diagnosis especially when using blood smears. The method described here can be of a great help when there is no access to classical cytogenetic analysis, or it might fail to give result. Sample preparation is easy, microscopic slides with the specimen can be transported via regular post to cytogenetic laboratories.

Child, Preschool↗
PubMed2001

pH-sensitive inwardly rectifying chloride current in cultured rat cortical astrocytes.

The effect of pH(o) on plasma membrane chloride current of cultured rat cortical astrocytes was investigated using the whole-cell patch-clamp technique. In the presence of intra- and extracellular solutions with symmetrical high Cl(-) content and K(+) channel inhibitors, the cells exhibited an inwardly rectifying current. The current activated slowly at potentials negative to -40 mV and did not display time-dependent inactivation. The current was inhibited by 0.1 mM Cd(2+), 0.1 mM Zn(2+), 1 mM 9-anthracene-carboxylic acid, and 0.2 mM 5-nitro-2-(3-phenylpropylamino)benzoic acid, but not by 10 mM Ba(2+) or 3 mM Cs(+). Reversal potential of the current followed the chloride equilibrium potential and was not influenced by changes in K(+) or Na(+) concentration. The inwardly rectifying chloride current was augmented by extracellular acidosis and reduced by alkalosis. The pH sensitivity was most pronounced in the physiologically relevant pH(o) range of 6.9--7.9. Lowering pH to 6.4 induced no additional increase in steady-state current amplitude compared with pH(o) 6.9, but it substantially slowed the activation kinetics. According to its kinetic and pharmacological properties this chloride current is similar to that found in cultured rat astrocytes after long-term treatment with dibutyryl-cAMP, however, in our cultures it was consistently expressed without any treatment with the drug. Considering that astrocytes possess carbonic anhydrase and Cl(-)/HCO3(-) antiporter, this current may participate in the regulation of the interstitial and astrocyte pH.

Animals↗
PubMed2001

AZFc deletion detected in a newborn with prenatally diagnosed Yq deletion.

A case of prenatally diagnosed Yq deletion is described. Fluorescence in situ hybridisation (FISH) was used to identify the abnormal chromosome and to exclude mosaicism. Based on the cytogenetic result and the ultrasound investigation the pregnancy was continued. A newborn with normal male genitalia was delivered. Microdeletion analysis of the Yq showed the absence of the AZFc region. This type of deletion has been described as being associated with azoospermia or oligozoospermia with a progressive decrease of sperm number over time. Long-term andrological follow-up of the newborn will be necessary with eventual cryoconservation of sperm at early adulthood. The present report proposes that AZF analysis combined with FISH has an important role in accurate genetic counselling in sex chromosome anomalies.

Adult↗
PubMed2001

[Processing vestibular impulses in the central nervous system. Study based on positron emission tomography].

BACKGROUND AND OBJECTIVE: Functional imaging methods have opened new perspectives for vestibular research. Many authors have investigated the central connections of the system, but the differences between the reports leave further questions open. We investigated the cerebral projection of the vestibular system, using positron emission tomography in right-handed subjects. PATIENTS AND METHODS: Bilateral caloric stimulation was used in every volunteer (n = 6). This can be considered a standard method, which will make it possible to compare the results from different laboratories in the future. A detailed map of activated and deactivated brain regions is included. RESULTS: Changes caused by vestibular stimulation are portrayed. The activated regions partially correspond with previous results in the literature. We would like to point out the Brodmann 6 region as the cortical manifestation of involuntary isometric tightening of muscles. We have found many, previously unidentified regions showing decreased regional cerebral blood flow. CONCLUSIONS: We are the first to point out the functional connection between the hippocampus and the vestibular system in this report.

Adult↗