Search Results

You are looking at 1 - 10 of 17 items for

  • Author or Editor: M. Papp x
  • All content x
Clear All Modify Search

In 1992 a 120 km long section of the Danube river, part of the border line between Hungary and Slovakia, was diverted into a new riverbed to put into operation the Gabčikovo (Bős-Nagymaros) Hydropower Plant. To follow up the environmental changes a monitoring system in the Szigetköz region, seriously affected by the diversion of the river, was established by the Hungarian Academy of Sciences. Results of the bryological monitoring work, conducted in the river branches are presented in this article. Today, the species composition of the aquatic-riparian bryophyte vegetation living in the various sections of the Szigetköz branch-system is different from that of 1991–1992. The abundance-frequency values of aquatic species have decreased, while the proportions of mesophilous long-lived species and short-lived bryophytes have increased. The changes of water requirement spectra of bryophyte vegetation and the growing importance of certain species groups indicate that the ecological conditions became drier. Apparently, the water supply system operated from 1995 provides insufficient amount of water and is inadequate to stop (and even less so to reverse) the environmental changes that took place in the branch-systems.

Restricted access
Acta Microbiologica et Immunologica Hungarica
Authors: Ildikó Nyilasi, T. Papp, M. Takó, Erzsébet Nagy, and Cs. Vágvölgyi

Iron is an essential nutrient for most organisms because it serves as a catalytic cofactor in oxidation-reduction reactions. Iron is rather unavailable because it occurs in its insoluble ferric form in oxides and hydroxides, while in serum of mammalian hosts is highly bound to carrier proteins such as transferrin, so the free iron concentration is extremely low insufficient for microbial growth. Therefore, many organisms have developed different iron-scavenging systems for solubilizing ferric iron and transporting it into cells across the fungal membrane. There are three major mechanisms by which fungi can obtain iron from the host: (a) utilization of a high affinity iron permease to transport iron intracellularly, (b) production and secretion of low molecular weight iron-specific chelators (siderophores), (c) utilization of a hem oxygenase to acquire iron from hemin. Patients with elevated levels of available serum iron treated with iron chelator, deferoxamine to remedy iron overload conditions have an increased susceptibility of invasive zygomycosis. Presumably deferoxamine predisposes patients to Zygomycetes infections by acting as a siderophore. The frequency of zygomycosis is increasing in recent years and these infections respond very poorly to currently available antifungal agents, so new approaches to develop strategies to prevent and treat zygomycosis are urgently needed. Siderophores and iron-transport proteins have been suggested to function as virulence factors because the acquisition of iron is a crucial pathogenetic event. Biosynthesis and uptake of siderophores represent possible targets for antifungal therapy.

Restricted access

The mortality rates of fungal infections that affect the central nervous system are high in consequence of the absence of effective antifungal drugs with good penetration across the blood-brain barrier and the blood-cerebrospinal fluid barrier. In the present work in vitro antifungal activities of three good penetrating non-antifungal drugs (amantadine hydrochloride, R-(-)-deprenyl hydrochloride, valproic acid sodium salt) and their combinations with three antifungal agents (amphotericin B, itraconazole, terbinafine) were tested with broth microdilution method against eight fungal isolates belonging to Zygomycetes (Lichtheimia corymbifera, Rhizomucor miehei, Rhizopus microsporus var. rhizopodiformis, Saksenaea vasiformis) and Aspergillus genus (A. flavus, A. fumigatus, A. nidulans, A. terreus). These are known to be possible agents of central nervous fungal infections (CNFI). When used alone, the investigated nonantifungal drugs exerted slight antifungal effects. In their combinations with antifungal agents they acted antagonistically, additively and synergistically against zygomyceteous isolates. Primarily antagonistic interactions were revealed between the investigated drugs in case of Aspergilli, but additive and synergistic interactions were also observed. The additive and synergistic combinations allowed the usage of reduced concentrations of antifungal agents to inhibit the fungal growth in our study. These combinations would be a basis of an effective, less toxic therapy for treatment of CNFI.

Restricted access

Intensification of land use in the last few decades resulted in an increased rate of fragmentation of natural forest habitats. With decreased patch size but increased total borderline length the influence of the surroundings also increased. The extent of influence is especially crucial where the forest stands are adjacent to agricultural lands. We studied the vegetation (cover) and seed bank (soil samples, seedling emergence) along adjacent stands of an abandoned vineyard and edge and interior of an oak forest community (Quercetum petraeae-cerris) widespread in Central-Europe, using five transects (16 m2 plots along each transect). We asked the following questions: (i) How do vegetation and seed bank composition differ between the vineyard and forest interior and (ii) which weeds are able to penetrate into the forest herbaceous understorey vegetation and seed banks from the vineyard? In total, 15 phanaerophytes and 147 herbs were detected. Negatively associated with canopy shading, herb cover proved the lowest in the forest inferior. Few weeds and other ruderals recorded in vineyard penetrated into the forest interior. Mean seed density decreased one order of magnitude from the vineyard to the forest interior (from 20,831 to 2,159 seed/m2). The seed banks of the abandoned vineyard and edge and forest interior were dominated by ruderals, but decreasing proportion of weeds was detected from the vineyard to the forest interior. Characteristic forest herbs possessed at most sparse seed banks. Our results suggest that high canopy cover mitigates the negative impact of surrounding weedy vegetation on the forest herb layer. Therefore, the effect of surroundings is detectable mostly in the seed banks. We can assume that the formation of an increased ruderal herb cover can be foreseen if canopy opens, because the local propagule sources of forest species are missing from vegetation and soil seed banks.

Restricted access
Journal of Thermal Analysis and Calorimetry
Authors: S. Papp, L. Kőrösi, B. Gool, T. Dederichs, P. Mela, M. Möller, and I. Dékány

Abstract  

Gold nanoparticles (Au NPs) were prepared by the reduction of HAuCl4 acid incorporated into the polar core of poly(styrene)-block-poly(2-vinylpyridine) (PS-b-P2VP) copolymer micelles dissolved in toluene. The formation of Au NPs was controlled using three reducing agents with different strengths: hydrazine (HA), triethylsilane (TES), and potassium triethylborohydride (PTB). The formation of Au NPs was followed by transmission electron microscopy, UV–Vis spectroscopy, isothermal titration calorimetry (ITC), and dynamic light scattering (DLS). It was found that the strength of the reducing agent determined both the size and the rate of formation of the Au NPs. The average diameters of the Au NPs prepared by reduction with HA, TES, and PTB were 1.7, 2.6, and 8 nm, respectively. The reduction of Au(III) was rapid with HA and PTB. TES proved to be a mild reducing agent for the synthesis of Au NPs. DLS measurements demonstrated swelling of the PS-b-P2VP micelles due to the incorporation of HAuCl4 and the reducing agents. The original micellar structure rearranged during the reduction with PTB. ITC measurements revealed that some chemical reactions besides Au NPs formation also occurred in the course of the reduction process. The enthalpy of formation of Au NPs in PS-b-P2VP micelles reduced by HA was determined.

Restricted access

A total of 126 bryophyte taxa (12 liverworts and 114 mosses) were collected in the Ibar gorge and its surroundings. The climate of the gorge receives Mediterranean influence, hence almost one fourth part of the species found are Mediterranean, sub-Mediterranean, or sub-Atlantic elements. Several rare species in Serbia and in the Balkans can be found in the territory (e.g. Bryum gemmiferum, Dialytrichia mucronata, Didymodon nicholsonii, Grimmia lisae, Gymnostomum viridulum, Hygroamblystegium humile, Orthotrichum obtusifolium, Syntrichia latifolia). One species (Buxbaumia viridis) is included in the Bern Convention and the European Union Habitats and Species Directives. The Ibar gorge maintains a unique bryophyte assemblage due to the serpentine bedrock and continental, Mediterranean climatic influence, which are the main characteristics of the region.

Restricted access
Acta Alimentaria
Authors: S. Balogh, F. Hajnal, B. Belec, M. Kómár, R. Papp, L. Nagymajtényi, and E. Paulik

Several risk factors of diet-related diseases are present in the nutrition of the Hungarian population. The aim of the study was to investigate the health status and the association of the daily consumption of fruits and vegetables as indicators of healthy diet with sociodemographic factors, health behaviours in the south-eastern part of Hungary. In 2002, a cross-sectional study based on interviewer-administered questionnaires was conducted in the south-eastern part of Hungary. The sample comprised of 3419 people, aged between 15 and 75, with about 40 persons from each practice. The results demonstrated that fruit and vegetable consumption of the studied population were determined by certain demographical, economical and lifestyle factors, and were also associated with self-assessed health and health status.  Altering the habits of nutrition is an integral part of health intervention programs. Success rate may, however, be largely reduced by the social and economic background of the habits in question.

Restricted access
Acta Alimentaria
Authors: M. Aloudat, A. Papp, N. Magyar, L. Simon Sarkadi, and A. Lugasi

The purpose of this study was to compare the energy content and macronutrients of forty main popular traditional and modern meals in both Jordan and Hungary with the national and international recommendations. The calculation of energy content and macronutrients were done on traditional and modern recipes by two different softwares (ESHA and NutriComp). Neither Jordanian nor Hungarian foods met the recommended energy content (35% of daily energy intake, 8400 kJ for energy intake). The recipes of both nations are characterised by higher protein, fat, and salt contents than WHO recommendation, a lower fibre content, and sugar content within the recommended limits. The fat energy ratio and saturated fatty acid content of Hungarian recipes are significantly higher than WHO recommendation. In general, Jordanian meals were more likely to meet the inclusion criteria. In conclusion, neither Jordanian nor Hungarian traditional and popular meals meet the international nutritional recommendations for a healthy diet, however, the composition of the real dishes may differ significantly from the recipes depending on the available ingredients and chosen kitchen technology.

Open access
Acta Biologica Hungarica
Authors: E. Horváth, G. Papp, Z. Gazdag, J. Belágyi, Á. Blaskó, J. Deli, Cs. Vágvölgyi, and M. Pesti

A carotenoid-less Phaffia rhodozyma mutant (MCP 325) exhibited significantly higher resistance to oxidative stressors such as menadione, H2O2 and K2Cr2O7 than its astaxanthin-producing parental strain (MCP 324). The absence of carotenoids in the mutant did not explain this phenomenon. The cause of the decreased superoxide, hydroxyl radical and glutathione contents, the increased peroxide concentration and the elevated specific activity of catalase under uninduced conditions may be a second mutation. Peroxide treatment induced specific catalase activity in the mutant but not in the parental strain. Regulation of these processes led to the result that, in spite of the mutations, the two strains exhibited the same multiplication rate and generation time.

Restricted access