Authors:Sz. Nagy, A. Kovács, T. Zubor, Z. Zomborszky, J. Tóth, and P. Horn
A simultaneous live/dead and acrosome staining, originally described for domestic mammals, was successfully applied on red deer (Cervus elaphus) and fallow deer (Dama dama) spermatozoa collected from the cauda epididymidis and vas deferens of shot stags. The staining is simple enough for routine application. Seven classes of spermatozoa were distinguished in the smears of frozen/thawed semen samples. Morphology, including cytoplasmic droplets, was evaluated as well. Percentage of live cells with intact acrosomes and with no other morphological aberrations might be a practical index of semen quality.
Authors:Marcell Clemens, E. Nagy-Baló, Cs. Herczku, Zs. Karányi, I. Édes, and Z. Csanádi
Aims: We investigated the influence of body mass index (BMI) on the prevalence of responder status in chronic heart failure patients after cardiac resynchronization therapy (CRT).
Methods: Data on 169 patients with resynchronization therapy were analyzed. Patients were categorized on the basis of the BMI measured at device implantation according to the WHO classification, as normal (BMI: 18.5–24.9 kg/m2), overweight (BMI: 25–29.9 kg/m2) or obese (BMI:≥30 kg/m2). Patients were considered responders if left ventricular ejection fraction was increased by at least 5% at 6-month follow-up.
Results: The mean age in the study population was 60.9±10.86 years (females 29%). The BMI subgroups did not exhibit any significant differences in baseline characteristics (age, gender, left ventricular ejection fraction or NYHA class). Elevated BMIs were associated with higher prevalence of responder status (overweight: 71.4%, obese: 63.0%) relative to subjects with a normal BMI (44.7%) (p=0.015).
Conclusions: In this CRT population, overweight status was associated with a more favorable response to CRT, indicating that the response may possibly be influenced by factors other than those directly related to the heart status or the technical details of the CRT.
Authors:Sz. Czóbel, O. Szirmai, J. Nagy, J. Balogh, Zs. Ürmös, E. Péli, and Z. Tuba
Grassland ecosystems in the Carpathian Basin may be particularly vulnerable to current and predicted changes in precipitation, and ecosystem responses to potential effects of water are not well understood. To examine how water addition can affect the species composition and structure, and CO
-flux of a Central European natural steppe plant community, grassland monoliths were irrigated for three consecutive years at Gödöllő, from 2002 through 2004. The loess grassland studied by
is a characteristic plant association of Hungary and similar vegetation can be found in other temperate regions. The treatment consisted of spray irrigation during night-time only in the growing season as well as aboveground biomass removal twice per year. Interannual and intraannual dynamics of species richness, Shannon Diversity, percentage cover, and different functional groups (monocots/dicots; plant life forms; social behaviour types; C
plants), and Net Ecosystem CO
Exchange in treated and untreated permanent plots, were studied simultaneously. To measure NEE and water vapour at stand level a self-developed, portable, non-destructive open chamber system (d=60cm) was used. The majority of the examined parameters varied considerably among years at both irrigated and control, but concerning carbon fluxes water addition effects were evident in dry periods only. At the treated plots, in general species richness, Shannon Diversity, the number of plant life forms and social behaviour types, the ratio of dicots and C
plants declined with addition of water. Our study proved that decline in species richness and Shannon diversity is not necessarily followed by the reduction of stand physiological (synphysiological) processes.
Authors:Z. Kemencei, R. Farkas, B. Páll-Gergely, F. Vilisics, A. Nagy, E. Hornung, and P. Sólymos
We determined microhabitat associations for 39 land snail species based on multimodel inference and generalized linear mixed models using a comprehensive and micro-scale data set from the Aggtelek Karst Area, Hungary. Patterns of microhabitat associations were highly nested among microhabitat types (litter, live trees, dead wood, rock) with high number of specialist species in dead wood and in rock microhabitats. Species composition was highly predictable in these microhabitats as opposed to live tree and litter faunas. Species richness was affected by microhabitat, topographic factors and local moisture conditions. Species richness in dead wood and rock microhabitats remained high irrespective of the topographic effects as opposed to litter and live tree microhabitats, where richness decreased with drier microhabitat conditions due to topography. Our results imply that consideration of topographic factors and microhabitat quality as part of coarse filter conservation measures could be beneficial to local land snail populations in the face of changing climate and disturbance regimes.
Authors:Á. Nagy, J. Bogáncs, J. Gyulai, A. Csőke, V. Nazarov, Z. Seres, A. Szabo, and Yu. Yazvitsky
A measuring technique based on the alpha particles being released from the10B(n, α) nuclear reaction and using the time-of-flight technique at a periodically pulsing reactor was developed. Non-destructive
determination for the range distribution of boron impurities in ion-implanted silicon have been performed. Projected ranges
obtained in the energy region 20–80 keV are compared to calculated results and to other experiments. Examples are shown for
some typical boron distributions before and after annealing the sample.
Authors:B Nagy, I Szabó, G Takács, B Csetényi, E Hormay, and Z Karádi
The mediodorsal prefrontal cortex (mdPFC) is a key structure of the central glucose-monitoring (GM) neural network. Previous studies indicate that intracerebral streptozotocin (STZ) microinjection-induced destruction of local chemosensory neurons results in feeding and metabolic alterations. The present experiments aimed to examine whether STZ microinjection into the mdPFC causes metabolic deficits. To do so, glucose tolerance test (GTT) and measurements of plasma metabolites were performed in STZ-treated or control rats. Intraperitoneal D-glucose load was delivered 20 min or 4 weeks following the intracerebral microinjection of STZ or saline (acute or subacute GTT, respectively). The STZ-treated rats displayed acute glucose intolerance: at the 120th min of the test, blood glucose level of these rats was significantly higher than that of the ones in the control group. When determining the plasma level of various metabolites, 30 min following the intracerebral STZ or saline microinjection, the triglyceride concentration of the STZ-treated rats was found to be reduced compared with that of the control rats. The GM neurons of the mdPFC are suggested to be involved in the organization of complex metabolic processes by which these chemosensory cells contribute to adaptive control mechanisms of the maintenance of homeostasis.
Authors:Gábor Takács, Cs. Szalay, B. Nagy, I. Szabó, D. Simon, T. Berki, and Z. Karádi
The nucleus accumbens (NAcc), an important basal forebrain structure, has a central integratory function in the control of feeding and metabolism. The primary cytokine interleukin-1β (IL-1β) exerts its neuromodulatory effects on the endocrine functions both centrally and peripherally. The present study was designed to elucidate the possible consequences of direct administration of IL-1β into the NAcc on the endocrine regulation of metabolism. Plasma concentrations of insulin and leptin, two key hormones in the homeostatic control were determined 15 minutes after a single bilateral microinjection of IL-1β into the NAcc of adult male Wistar rats, and the effects were compared with those found in vehicle treated control animals. Insulin plasma levels of the cytokine treated animals were significantly higher than those parameters of the control rats. No differences were found in leptin plasma concentrations between the two groups. Our findings show that IL-1β mediated processes in the NAcc have important roles in the central neuroendocrine control.
Authors:Ama Szmolka, Barbara Lestár, Judit Pászti, Péter Z. Fekete, and Béla Nagy
Enterotoxigenic E. coli (ETEC) bacteria frequently cause watery diarrhoea in newborn and weaned pigs. Plasmids carrying genes of different enterotoxins and fimbrial adhesins, as well as plasmids conferring antimicrobial resistance are of prime importance in the epidemiology and pathogenesis of ETEC. Recent studies have revealed the significance of the porcine ETEC plasmid pTC, carrying tetracycline resistance gene tet(B) with enterotoxin genes. In contrast, the role of tet(A) plasmids in transferring resistance of porcine ETEC is less understood. The objective of the present study was to provide a comparative analysis of antimicrobial resistance and virulence gene profiles of porcine post-weaning ETEC strains representing pork-producing areas in Central Europe and in the USA, with special attention to plasmids carrying the tet(A) gene. Antimicrobial resistance phenotypes and genotypes of 87 porcine ETEC strains isolated from cases of post-weaning diarrhoea in Austria, the Czech Republic, Hungary and the Midwest USA was determined by disk diffusion and by PCR. Central European strains carrying tet(A) or tet(B) were further subjected to molecular characterisation of their tet plasmids. Results indicated that > 90% of the ETEC strains shared a common multidrug resistant (MDR) pattern of sulphamethoxazole (91%), tetracycline (84%) and streptomycin (80%) resistance. Tetracycline resistance was most frequently determined by the tet(B) gene (38%), while tet(A) was identified in 26% of all isolates with wide ranges for both tet gene types between some countries and with class 1 integrons and resistance genes co-transferred by conjugation. The virulence gene profiles included enterotoxin genes (lt, sta and/or stb), as well as adhesin genes (k88/f4, f18). Characterisation of two representative tet(A) plasmids of porcine F18+ ETEC from Central Europe revealed that the IncF plasmid (pES11732) of the Czech strain (~120 kb) carried tet(A) in association with catA1 for chloramphenicol resistance. The IncI1 plasmid (pES2172) of the Hungarian strain (~138 kb) carried tet(A) gene and a class 1 integron with an unusual variable region of 2,735 bp composed by two gene cassettes: estX-aadA1 encoding for streptothricin-spectinomycin/streptomycin resistance exemplifying simultaneous recruitment, assembly and transfer of multidrug resistance genes by the tet(A) plasmid of porcine ETEC. By this we provide the first description of IncF and IncI1 type plasmids of F18+ porcine enterotoxigenic E. coli responsible for cotransfer of the tet(A) gene with multidrug resistance. Additionally, the unusual determinant estX, encoding for streptothricin resistance, is first reported here in porcine enterotoxigenic E. coli.
Authors:A. Szabo, A. Fonseca, L. P. Biro, Z. Konya, I. Kiricsi, A. Volodin, C. Van Hasendonck, and J. B.Nagy
Some recent results on
the synthesis of coiled carbon nanotubes (CNTs) are summarized. Several
supported catalysts can lead to the formation of coiled CNTs. Interestingly,
certain domains of the coil pitch and coil diameter are favoured, and two
“stability islands”are found in the 3D representation of the number of coiled
CNTs as a function of both coil pitch and coil diameter. It is emphasized that
these nanotubes are formed either by introducing pairs of five-membered ring -
seven-membered ring or by forming haeckelite structures. The coiled CNTs could
be used in nanocomposite reinforcement as well as special sensors based on
their remarkable mechanical and electrical properties.
Authors:J. B.Nagy, J. N. Coleman, A. Fonseca, A. Destrée, Z. Mekhalif, N. Moreau, L. Vast, and J. Delhalle
Organic polymers -
carbon nanotubes nanocomposites are synthesized either by mechanical mixing of
the two components or by covalently linking the nanotubes to the matrix. The
various procedures will be overviewed and the determining factors will be
identified for the best mechanical properties of the composites. On the other
hand, it will be shown that for highest electrical conductivity much smaller
amounts of carbon nanotubes are needed if the nanotubes can be aligned. The
thermal conductivity of the nanocomposites will also be overviewed. Finally,
together with nanoclay particles, nanotubes are inducing remarkable flame
retardant properties in the nanocomposites materials.