Biomedical subjects

B Tóth

Publications and source records attributed to B Tóth.

At least 19 recordsLinked to original sources

PubMed2006

Investigation of long-term stress induced by several stressors by determination of the concentration of different blood plasma components in a model of Prussian carp (Carassius auratus gibelio BLOCH, 1783) and Common carp (Cyprinus carpio L., 1758).

Several compounds (carbohydrates, proteins, hormones, etc.) were used in fish to quantify the level of stress. Our investigations focused on two parameters of the blood plasma: plasma glucose and serum/plasma fructosamine (SeFa) that has not been tested on fish as yet. Experiments were conducted on two fish species. The concentrations of these components were investigated on Common carp (Cyprinus carpio L., 1758) and on Prussian carp (Carassius auratus gibelio BLOCH, 1783) from the Gödöllö-Isaszeg pond system by creating conditions different from ideal. Stress effects caused a fluctuating tendency in blood plasma glucose levels each week for both Common carp and Prussian carp, thus, there was no steady growth. However, SeFa concentrations exactly followed stress effects, moreover, it tolerated short-term negative effects (handling of fish, blood sampling) and did not cause alterations at individuals blood samplings. This experimental method can offer assistance to farmers in the daily routine (e.g. in fish transport) and in the technology of propagation.

Animals↗

PubMed2005

Nonlinear adsorption isotherm as a tool for understanding and characterizing molecularly imprinted polymers.

Molecularly imprinted polymers (MIPs) have frequently been characterized by quantities which are easily determined from experiments but have no theoretical foundation. This makes it difficult to compare different MIP preparations or to transfer MIP based methods to different experimental conditions. Since the adsorption isotherms of MIPs are markedly nonlinear, one can build a better characterization strategy on isotherms as shown by examples in this paper.

Adsorption↗

PubMed2005

Chromatographic behavior of silica-polymer composite molecularly imprinted materials.

Molecularly imprinted polymers (MIP) have recently been prepared inside the pores of silica based HPLC packing materials. Detailed physical and chromatographic characterization of such a silica-MIP composite material is presented. The chromatographic peak shape obtained with the uniformly sized spherical silica-MIP composite is mainly determined by the nonlinear adsorption isotherm. Comparison of the composite with the conventional sieved and grinded bulk MIP is therefore based on the nonlinear isotherm and not on retention factors and plate numbers.

Chromatography, High Pressure Liquid↗

PubMed2005

Ischemia reperfusion injury of the skeletal muscle after selective deafferentation.

The present study analyzes the effect of selective deafferentation on the reperfusion injury of the skeletal muscle when nociceptive sensory fibers of the left sciatic nerve are selectively damaged by capsaicin pretreatment in a rat model following tourniquet ischemia (ISC) applied for 30 min, 1 h, and 2 h on the left hind limb. The isometric tetanic contractile force of the extensor digitorum longus (EDL) muscle was measured after 1 h, and 1, 3, or 7 days of reperfusion. Contractile force of the damaged muscle was compared to the intact contralateral muscle. In another group, ISC was used without capsaicin pre-treatment. After 30 min of ISC, there was no difference between deafferented and non-pretreated groups. Following 1 h ISC, with the exception of 1 h reperfusion, the non-pretreated group produced stronger contractions than the deafferented group. After 2 h ISC, the contractile force of the deafferented muscle was significantly stronger compared to the non-deafferented muscle force at all reperfusion times. In conclusions, it was found that the absence of peptidergic sensory fibers after long-lasting (2 h) ischemia is beneficial in reperfusion injury, whereas the absence of vasodilator peptides has unfavorable effects if tissue damage is milder (after 1 h ischemia).

Animals↗

PubMed2003

Two loci on chromosome 5H determine low-temperature tolerance in a 'Nure' (winter) x 'Tremois' (spring) barley map.

Barley ( Hordeum vulgare subsp. vulgare) is an economically important diploid model for the Triticeae; and a better understanding of low-temperature tolerance mechanisms could significantly improve the yield of fall-sown cereals. We developed a new resource for genetic analysis of winter hardiness-related traits, the 'Nure' x 'Tremois' linkage map, based on a doubled-haploid population that is segregating for low-temperature tolerance and vernalization requirement. Three measures of low-temperature tolerance and one measure of vernalization requirement were used and, for all traits, QTLs were mapped on chromosome 5H. The vernalization response QTL coincides with previous reports at the Vrn-1/Fr1 region of the Triticeae. We also found coincident QTLs at this position for all measures of low-temperature tolerance. Using Composite Interval Mapping, a second proximal set, of coincident QTLs for low-temperature tolerance, and the accumulation of two different COR proteins (COR14b and TMC-Ap3) was identified. The HvCBF4 locus, or another member of the CBF loci clustered in this region, is the candidate gene underlying this QTL. There is a CRT/DRE recognition site in the promoter of cor14b with which a CBF protein could interact. These results support the hypothesis that highly conserved regulatory factors, such as members of the CBF gene family, may regulate the stress responses of a wide range of plant species.

Acclimatization↗

PubMed2003

Mapping genes affecting flowering time and frost resistance on chromosome 5B of wheat.

Two populations of single chromosome recombinant lines were used to map genes controlling flowering time on chromosome 5B of wheat, and one of the populations was also used to map a new frost resistance gene. Genetic maps were developed, mainly using microsatellite markers, and QTL analysis was applied to phenotypic data on the performance of each population collected from growth-room tests of flowering time and frost tolerance. Using a recombinant substitution-line mapping population derived from a cross between the substitution-line 'Chinese Spring' ('Cheyenne' 5B) and 'Chinese Spring' (CS), the gene Vrn-B1, affecting vernalization response, an earliness per se locus, Eps-5BL1, and a gene, Fr-B1, affecting frost resistance, were mapped. Using a 'Hobbit Sib' ('Chinese Spring' 5BL) x 'Hobbit Sib' recombinant substitution line mapping population, an earliness per se locus, Eps-5BL2 was mapped. The Vrn-B1 locus was mapped on the distal portion of the long arm of chromosome 5B, to a region syntenous with the segments of chromosomes 5A and 5D containing Vrn-A1 and Vrn-D1 loci, respectively. The two Eps-5BL loci were mapped close to the centromere with a 16-cM distance from each other, one in agreement with the position of a homoeologous locus previously mapped on chromosome 5H of barley, and suggested by the response of 'Chinese Spring' deletion lines. The Fr-B1 gene was mapped on the long arm of chromosome 5B, 40 cM from the centromeric marker. Previous comparative mapping data with rice chromosome 9 would suggest that this gene could be orthologous to the other Fr genes mapped previously by us on chromosomes 5A or 5D of wheat, although in a more proximal position. This study completes the mapping of these homoeoallelic series of vernalization requirement genes and frost resistance genes on the chromosomes of the homoeologous group 5 in wheat.

Acclimatization↗

PubMed2001

Synthesis of and a comparative study on the inhibition of muscle and liver glycogen phosphorylases by epimeric pairs of d-gluco- and d-xylopyranosylidene-spiro-(thio)hydantoins and N-(d-glucopyranosyl) amides.

D-Gluco- and D-xylopyranosylidene-spiro-hydantoins and -thiohydantoins were prepared from the parent sugars in a six-step, highly chemo-, regio-, and stereoselective procedure. In the key step of the syntheses C-(1-bromo-1-deoxy-beta-D-glycopyranosyl)formamides were reacted with cyanate ion to give spiro-hydantoins with a retained configuration at the anomeric center as the major products. On the other hand, thiocyanate ions gave spiro-thiohydantoins with an inverted anomeric carbon as the only products. On the basis of radical inhibition studies, a mechanistic rationale was proposed to explain this unique stereoselectivity and the formation of C-(1-hydroxy-beta-D-glycopyranosyl)formamides as byproducts. Enzyme assays with a and b forms of muscle and liver glycogen phosphorylases showed spiro-hydantoin 12 and spiro-thiohydantoin 14 to be the best and equipotent inhibitors with K(i) values in the low micromolar range. The study of epimeric pairs of D-gluco and D-xylo configurated spiro-hydantoins and N-(D-glucopyranosyl)amides corroborated the role of specific hydrogen bridges in binding the inhibitors to the enzyme.

Amides↗

PubMed2001

Molecular targets for pharmacological cytoprotection.

Cell death is common to many pathological conditions. In the past two decades, research into the mechanism of cell death has characterized the cardinal features of apoptosis and necrosis, the two distinct forms of cell death. Studies using in vivo disease models have provided evidence that apoptosis is induced by an array of pathological stimuli. Thus, molecular components of the machinery of apoptosis are potential pharmacological targets. The mechanism of apoptosis can be dissected into: (i) the initiation and signaling phase, (ii) the signal amplification phase, and (iii) the execution phase. Reflecting on the diversity of apoptotic stimuli, the initiation and signaling phase utilizes a variety of molecules: free radicals, ions, plasma membrane receptors, members of the signaling kinase cascades, transcription factors, and signaling caspases. In most of the apoptotic scenarios, impairment of mitochondrial function is an early event. Dysfunctioning mitochondria release more free radicals and hydrolytic enzymes (proteases and nucleases), amplifying the primary death signal. In the final phase of apoptosis, executioner caspases are activated. Substrates of the executioner caspases include nucleases, members of the cellular repair apparatus, and cytoskeletal proteins. Partial proteolysis of these substrates leads to distinctive morphological and biochemical changes, the hallmarks of apoptosis. The first steps toward pharmacological utilization of specific modifiers of apoptosis have been promising. However, since the potential molecular targets of cytoprotective therapy play important roles in the maintenance of cellular homeostasis, specificity (diseased versus healthy tissue) of pharmacological modulation is the key to success.

Animals↗

PubMed2001

Glutathione reductase activity and chilling tolerance are induced by a hydroxylamine derivative BRX-156 in maize and soybean.

The possible contribution of antioxidants in the improvement of stress tolerance induced by the hydroxylamine derivative BRX-156 was studied in two thermophilic crops, soybean (Glycine max (L.) Merr.) and maize (Zea mays L.) both during germination and at the seedling stage. The most effective concentration of BRX-156 for an increase in stress tolerance was determined by the complex stressing vigour test (CSVT), in which seeds were germinated under simultaneous anoxia and chilling (5 degrees C) stresses. Under CSVT conditions the activity of glutathione reductase (GR, EC 1.6.4.2), was increased by BRX-156 by up to 200 and 150% in soybean and maize, respectively. Treatment with BRX-156 only resulted in a significantly greater activity of glutathione S-transferase (GST, EC 2.5.1.18) in maize. When young seedlings were chilled at 5 degrees C for a week, the increase in recovery induced by BRX-156 was accompanied by increased GR activity. The GSH synthesis was not affected by BRX-156 under these conditions. Induction of GR activity contributes to the improvement of abiotic stress tolerance by BRX-156 in maize and soybean.

Journal Article↗

PubMed2001

Double-stranded rna elements and virus-like particles in Aspergilli.

Mycoviruses with double-stranded RNA (dsRNA) genomes are frequently encountered in Aspergillus isolates. A detailed study of such dsRNA elements in black Aspergillus isolates collected worldwide was carried out, and the data were analysed. The results indicate that about 10% of black Aspergilli are infected. However, the geographic distribution of infected isolates exhibits large variations; 3-13% of the isolates collected from different continents were found to carry dsRNA elements. Hybridization experiments indicated that electrophoretic banding patterns are not reliable tools for estimating the diversity of these mycovirus genomes. Among strains representing other Aspergillus sections, dsRNA segments indicative of mycovirus infection were observed for the first time in 4 species (A. leporis, A. petrakii, A. fumigatus and A. primulinus). The latter species is able to reproduce sexually. This is the second report on the detection of naturally-occurring dsRNAs in sexually reproducing Aspergillus species. The presence of virus-like particles in these and other Aspergilli was also examined by electron microscopy. Most infected Aspergillus isolates examined were found to carry virus-like particles in the size range 36-40 nm.

Aspergillus↗

PubMed2001

[Pancreatic injury in blunt abdominal trauma: early versus late diagnosis and surgical management].

Pancreatic trauma is relatively uncommon, but it has high morbidity and mortality rates, especially when the diagnosis is delayed or inappropriate surgery is attempted. We analysed the management of 11 patients in a university teaching hospital treated with distal pancreatic transsection without (grade II--according AAST score) and with main pancreatic duct (MPD) injury (grade III) caused by blunt abdominal trauma. The average age of the 10 male and 1 female patients was 24.9 years (5-56). Five patients had isolated pancreatic trauma, other 6 patients had 2.3 associated intraabdominal and 0.8 associated extraabdominal injuries. Six patients were diagnosed and operated within the first 24 hours. Five of them had transsection of the gland with main pancreatic duct injury, distal pancreatectomy with (2) or without (1) splenectomy, distal pancreatogastrostomy (1), and (due to associated duodenal laceration) pylorus-preserving pancreatoduodenectomy (1) were performed. In one case (grade II) only external drainage was necessary. All patients in this group who were operated on early survived. Only one patient needed reoperation due to haemorrhage after pancreatoduodenectomy. From the other five patients four were referred after initial treatment in a primary centre (all of them underwent some kind of external drainage), and in one patient the diagnosis of pancreatic injury was missed at the initial operation in our hospital. Three of them had undetected MPD injury, in two patients parenchymal lesions were underestimated or missed. Every patients needed subsequent resection (1), internal drainage due to fistula (2), or drainage of developed abscess (2). Three of them had severe septic and pulmonary complications; one patient with MPD injury died. Patients who require delayed surgery after an unsuccessful period of conservative treatment or a subsequent operation due to undetected MPD injury demonstrated higher pancreas-specific mortality and morbidity rate.

Abdominal Injuries↗

PubMed2000

Phylogenetic analysis of Aspergillus section Circumdati based on sequences of the internal transcribed spacer regions and the 5.8 S rRNA gene.

Phenotypic features and sequences of the internal transcribed spacer (ITS) regions and the 5.8 S rRNA gene of type or neotype strains and other isolates of the 17 species currently assigned to Aspergillus section Circumdati and some potentially related species were analyzed. Parsimony analysis of sequence data indicated that Aspergillus section Circumdati is paraphyletic. Aspergillus campestris, A. lanosus, and A. dimorphicus with A. sepultus were found to be more closely related to Aspergillus sections Candidi, Flavi, and Cremei, respectively. These results were also supported by phenotypic data. A. robustus and A. ochraceoroseus were found not to be related to any of the species examined. Species of the proposed revised Aspergillus section Circumdati formed two main clades, which could also be distinguished based on phenotypic methods. Phylogenetic analysis of sequence data of other isolates assigned to species of the revised section indicates that either some of these isolates were misidentified or species concepts of A. ochraceus, A. melleus, and A. petrakii should be reconsidered.

Aspergillus↗

PubMed2000

Genetic variability within the Aspergillus viridinutans species.

The intraspecific variability of the Aspergillus viridinutans species was examined using various techniques including morphological examinations, carbon-source-utilization tests, restriction-enzyme analysis of the mitochondrial and nuclear DNA, and sequence analysis of part of the beta-tubulin gene. Although the genetic distances between the isolates were higher than between, e.g., A. fumigatus and Neosartorya fischeri, most A. viridinutans isolates, together with N. aureola and N. udagawae strains, were found to belong to a single cluster based on sequence data. Strain FRR 1266, which was earlier classified as a highly divergent A. fumigatus isolate, was found to belong to the A. viridinutans species. The ochratoxin A producing A. viridinutans strain IMI 306135 was most closely related to an asexual isolate. These two latter strains were more closely related to A. fumigatus and N. fischeri than to any A. viridinutans strains, and possibly represent a new species in the Aspergillus section Fumigati. The dendrogram based on carbon source utilization data and results of restriction analysis of the mitochondrial and nuclear DNA of the strains supported most of the evolutionary relationships observed on the basis of sequence data. The results indicate that the presence or absence of nodding conidial heads is not an unequivocal morphological character for the identification of species within the Aspergillus section Fumigati.

Animals↗

PubMed2000

Analysis of genetic variability within the genus Petromyces.

Phenotypic and genotypic features of three teleomorphic species, Petromyces alliaceus, P. albertensis and P. muricartus and some related anamorphic Aspergillus species were compared. The dendrogram based on carbon source utilisation data revealed a close relationship between P. muricarus and the A. ochraceus strains examined. P. alliaceus and P. albertensis strains were very closely related to each other. A dendrogram with similar topology was obtained by analysing sequences of the intergenic transcribed spacer regions of representatives of these species. P. alliaceus and P. albertensis strains could only be distinguished by the random amplified polymorphic DNA technique. These strains possibly represent a single species closely related to Aspergillus section Flavi, while the anamorph of P. turicatus is a member of Aspergillus section Circumdati. Our results indicate that Aspergillus section Circumdati is in need of taxonomic revision.

Ascomycota↗

PubMed2000

Phylogenetic analysis of newly described Neosartorya species.

Isolates representing newly described Neosartorya species, and isolates with abnormal morphologies from Aspergillus section Fumigati were examined by phylogenetic analysis of sequences of part of their beta-tubulin gene. Phylogenetic analyses supported the earlier suggestions that heterothallism is a derived character, and that sexuality was lost several times during the evolution of Aspergillus section Fumigati. The heterothallic N. fennelliae and N. udagawae strains were found to be closely related to the homothallic Neosartorya sp. NRRL 4179 and N. aureola, respectively. Aspergillus sp. FRR 1266, which was earlier described as a variant of A. fumigatus, was found to be closely related to A. viridinutans. Another abnormal asexual isolate was found to be closely related to A. fumigatus and N. fischeri. Phylogenetic relationships among newly described Neosartorya species and other taxa were successfully established based on phylogenetic analysis of beta-tubulin sequences.

DNA, Fungal↗

PubMed2000

beta-amyloid neurotoxicity is mediated by a glutamate-triggered excitotoxic cascade in rat nucleus basalis.

Whereas a cardinal role for beta-amyloid protein (Abeta) has been postulated as a major trigger of neuronal injury in Alzheimer's disease, the pathogenic mechanism by which Abeta deranges nerve cells remains largely elusive. Here we report correlative in vitro and in vivo evidence that an excitotoxic cascade mediates Abeta neurotoxicity in the rat magnocellular nucleus basalis (MBN). In vitro application of Abeta to astrocytes elicits rapid depolarization of astroglial membranes with a concomitant inhibition of glutamate uptake. In vivo Abeta infusion by way of microdialysis in the MBN revealed peak extracellular concentrations of excitatory amino acid neurotransmitters within 20-30 min. Abeta-triggered extracellular elevation of excitatory amino acids coincided with a significantly enhanced intracellular accumulation of Ca2+ in the Abeta injection area, as was demonstrated by 45Ca2+ autoradiography. In consequence of these acute processes delayed cell death in the MBN and persistent loss of cholinergic fibre projections to the neocortex appear as early as 3 days following the Abeta-induced toxic insult. Such a sequence of Abeta toxicity was effectively antagonized by the N-methyl-D-aspartate (NMDA) receptor ligand dizocilpine maleate (MK-801). Moreover, Abeta toxicity in the MBN decreases with advancing age that may be associated with the age-related loss of NMDA receptor expression in rats. In summary, the present results indicate that Abeta compromises neurons of the rat MBN via an excitotoxic pathway including astroglial depolarization, extracellular glutamate accumulation, NMDA receptor activation and an intracellular Ca2+ overload leading to cell death.

Alzheimer Disease↗

PubMed2000

Molecular analysis of variability within the toxigenic Aspergillus ochraceus species.

Genetic variability of Aspergillus ochraceus was examined at the DNA level. Based on the HaeIII-Bg/II generated mitochondrial DNA restriction profiles, most isolates could be classified into two distinct groups. These two groups could also be distinguished by the random amplified polymorphic DNA technique, and with telomeric PCR amplifications. Phylogenetic analysis of sequences of the intergenic transcribed spacer region of some of the strains resulted in a dendrogram with the same topology as that based on mitochondrial DNA and amplified DNA data. None of the isolates with type 2 mtDNA profiles produce ochratoxins. Some strains (e.g., A. ochraceus ICMP 939) displayed strain-specific mitochondrial DNA patterns, and their amplified DNA profiles were also different from all other A. ochraceus strains examined.

Aspergillus↗

PubMed2000

Pathological and immunological study of an in ovo complex vaccine against infectious bursal disease.

The appearance of very virulent strains of infectious bursal disease (IBD) virus at the end of the 1980s made it necessary to develop more effective immunization procedures. To facilitate this, the immunogenicity and the immunosuppressive effect of a mild (G-87), an intermediate (LIBD) and an intermediate-plus (IBDV 2512) IBDV strain were tested after the in ovo inoculation of 18-day-old SPF and broiler chicken embryos. It was established that no noteworthy difference existed between the immunized and the control embryos in hatching rate and hatching weight. The higher the virulence of the vaccine virus strain, the more severe damage it caused to the lymphocytes of the bursa of Fabricius. In SPF chickens, the haemagglutination inhibition (HI) titres induced by a Newcastle disease (ND) vaccine administered at day old decreased in inverse ratio to the virulence of the IBD vaccine strain, while in broiler chickens this was not observed. Despite the decrease of the HI titre, the level of protection did not decline, or did so only after the use of the 'hot' strain. SPF chickens immunized in ovo with a complex vaccine prepared from strain IBDV 2512 and IBD antibody showed the same protection against Newcastle disease as the broilers. In broiler chicken embryos immunized in ovo, only strain IBDV 2512 induced antibody production, and such chickens were protected against IBD at 3 weeks of age. The complex vaccine administered in ovo has been used successfully at farm hatcheries as well.

Animals↗