Showing papers by "Jagiellonian University published in 1999"
TL;DR: In this paper, the authors present X-ray/γ-ray spectra of Cyg X-1 observed during the transition from the hard to the soft state and in the soft states by ASCA, RXTE and CGRO/OSSE in 1996 May and June.
Abstract: We present X-ray/γ-ray spectra of Cyg X-1 observed during the transition from the hard to the soft state and in the soft state by ASCA, RXTE and CGRO/OSSE in 1996 May and June. The spectra consist of a dominant soft component below ∼2 keV and a power-law-like continuum extending to at least ∼800 keV. We interpret them as emission from an optically thick, cold accretion disc and from an optically thin, non-thermal corona above the disc. A fraction f≳0.5 of total available power is dissipated in the corona.
We model the soft component by multicolour blackbody disc emission taking into account the torque-free inner-boundary condition. If the disc extends down to the minimum stable orbit, the ASCARXTE data yield the most probable black hole mass of MX≈10 M⊙ and an accretion rate, , locating Cyg X-1 in the soft state in the upper part of the stable, gas-pressure-dominated, accretion-disc solution branch.
The spectrum of the corona is well modelled by repeated Compton scattering of seed photons from the disc off electrons with a hybrid, thermal/non-thermal distribution. The electron distribution can be characterized by a Maxwellian with an equilibrium temperature of kTe∼30–50 keV, a Thomson optical depth of τ∼0.3 and a quasi-power-law tail. The compactness of the corona is 2≲lh≲7, and a presence of a significant population of electron–positron pairs is ruled out.
We find strong signatures of Compton reflection from a cold and ionized medium, presumably an accretion disc, with an apparent reflector solid angle, Ω/2π∼0.5–0.7. The reflected continuum is accompanied by a broad iron Kα line.
486 citations
TL;DR: In male subjects with EH, endogenous systemic NO formation appears depressed, which is unrelated to accompanying insulin resistance or dyslipidemia, and circulating methylated analogs of L-arginine levels are increased in uncomplicated EH which may be of potential relevance.
Abstract: Summary:Our aim was to investigate systemic nitric oxide (NO) production and its potential determinants such as insulin resistance, dyslipidemia, and circulating methylated analogs of L-arginine in uncomplicated essential hypertension (EH). Nineteen newly diagnosed, untreated male subjects with mild
433 citations
TL;DR: It is proposed that PAD, acting in concert with arginine-specific proteinases from P. gingivalis, promotes the growth of the pathogen in the periodontal pocket, initially by enhancing its survivability and then by assisting the organism in its circumvention of host humoral defenses.
Abstract: The initiation and progression of adult-onset periodontitis has been associated with infection of the gingival sulcus by Porphyromonas gingivalis. This organism utilizes a multitude of virulence factors to evade host defenses as it establishes itself as one of the predominant pathogens in periodontal pockets. A feature common to many other oral pathogens is the production of ammonia due to its protective effect during acidic cleansing cycles in the mouth. Additionally, ammonia production by P. gingivalis has been proposed as a virulence factor due to its negative effects on neutrophil function. In this study, we describe the first purification of a peptidylarginine deiminase (PAD) from a prokaryote. PAD exhibits biochemical characteristics and properties that suggest that it may be a virulence agent. PAD deiminates the guanidino group of carboxyl-terminal arginine residues on a variety of peptides, including the vasoregulatory peptide-hormone bradykinin, to yield ammonia and a citrulline residue. The soluble protein has an apparent mass of 46 kDa, while the DNA sequence predicts a full-length protein of 61.7 kDa. PAD is optimally active at 55 degrees C, stable at low pH, and shows the greatest activity above pH 9.0. Interestingly, in the presence of stabilizing factors, PAD is resistant to limited proteolysis and retains significant activity after short-term boiling. We propose that PAD, acting in concert with arginine-specific proteinases from P. gingivalis, promotes the growth of the pathogen in the periodontal pocket, initially by enhancing its survivability and then by assisting the organism in its circumvention of host humoral defenses.
363 citations
TL;DR: The study of the interaction of two synthetic melanins with a wide range of oxidising and reducing free radicals using the pulse radiolysis technique suggests that the free radical scavenging properties of melanin may be important in the protection of melanotic cells against free radical damage.
300 citations
TL;DR: A lot of work is now focused on this specific area in order to clarify the role of oestrogens in the reproductive tract of the male as well as to elucidate the regulation of aromatase gene expression.
Abstract: The cytochrome P450 aromatase (P450arom) is the terminal enzyme responsible for the irreversible transformation of androgens into oestrogens and is present in the endoplasmic reticulum of various tissues throughout at least the phylum of vertebrates. The CYP 19 gene is unique and its expression is regulated in a tissue and more precisely in a cell-specific fashion via the alternative use of several promoters located in the first exons. The P450arom has been immunolocalized in germ cells of the mouse, brown bear and rooster. According to age, aromatase activity has been measured in immature and mature rat Leydig cells as well as in Sertoli cells, whereas in the pig, ram and human aromatase is mainly present in Leydig cells. In the adult rat testis, four complementary approaches (RTPCR, in situ hybridization, immunocytochemistry and the tritiated water assay) demonstrate that not only somatic cells but also mature germ cells represent a source of oestrogen synthesis. Taking into account the widespread distribution of oestrogen receptors (ER alpha & ER beta) in testicular cells and the genital tract of the male on the one hand, and the cross-talk between sex steroids and growth factors, and between membrane receptors and nuclear receptors for steroids on the other hand, it is anticipated that understanding of the pathophysiological roles of these 'female' hormones in the male will advance understanding of the hormonal regulation of male reproductive function. One of the future goals is to define oestrogen-targeted genes in the male gonad and indeed, a lot of work is now focused on this specific area in order to clarify the role of oestrogens in the reproductive tract of the male as well as to elucidate the regulation of aromatase gene expression.
206 citations
01 Jan 1999
TL;DR: A critical examination of the literature reveals that HMs react with the photosynthetic apparatus at various levels of organization and architecture i.e. accumulation of metals in leaf, partitioning in leaf tissues like stomata, mesophyll and bundle sheath, metal interaction with cytosolic enzymes and organics, alteration of the functions of chloroplast membranes; supramolecular level action, particularly on PS II, PS I, membrane acyl lipids, and carrier proteins in vascular tissues; molecular level interactions, particularly with photosyntynthetic carbon reduction cycle enzymes, x
Abstract: Use of phytotoxicity of metallic compounds dates back to 1896, when the French farmers applied Bordeaux mixture (copper sulphate, lime and water) to control fungal pests (Martin and Woodcock 1983). Currently, global heavy metal (HM) pollution is a serious environmental concern. Photosynthetic functions have been invariably affected either directly or indirectly by HMs (Baszynski and Tukendorf 1984; Clijsters and Van Assche 1985; Baszytniski 1986; Sheoran et al. 1990; Greger and Ogren 1991; Krupa and Baszynski 1985, 1995; Prasad 1995a, 1997). A critical examination of the literature reveals that HMs react with the photosynthetic apparatus at various levels of organization and architecture i.e. accumulation of metals in leaf (main photosynthetic organ); partitioning in leaf tissues like stomata, mesophyll and bundle sheath; metal interaction with cytosolic enzymes and organics; alteration of the functions of chloroplast membranes; supramolecular level action, particularly on PS II, PS I, membrane acyl lipids, and carrier proteins in vascular tissues; molecular level interactions, particularly with photosynthetic carbon reduction cycle enzymes, xanthophyll cycle and adenylates.
204 citations
TL;DR: It is shown that relatively stable charge associations (charge pairs) are formed between the positively and negatively charged groups of two DMPC molecules.
201 citations
University of Mainz1, GSI Helmholtz Centre for Heavy Ion Research2, Michigan State University3, Kurchatov Institute4, Chalmers University of Technology5, Spanish National Research Council6, Technische Universität Darmstadt7, Goethe University Frankfurt8, University of Basel9, University of Silesia in Katowice10, Jagiellonian University11, Aarhus University12
TL;DR: Aumann et al. as discussed by the authors used PACS number(s): 27.20.Gc, 25.60.De, 29.1n,25.70.Hs
Abstract: T. Aumann et al. ; 11 pags.; 6 figs.; 2 tabs. ; PACS number(s): 27.20.1n, 25.60.Gc, 25.70.De, 29.30.Hs
201 citations
TL;DR: In this paper, the changes in the structure of wool fiber keratin were studied by means of Fourier-transform Infrared and Raman Spectroscopy, and the attempt of interruption of this process in the presence of siliceous compounds was made.
189 citations
TL;DR: The binding mode of an arginine‐containing inhibitor in the active‐site is shown, thus identifying major interaction sites defining a suitable pharmacophor.
Abstract: Gingipains are cysteine proteinases acting as key virulence factors of the bacterium Porphyromonas gingivalis, the major pathogen in periodontal disease. The 1.5 and 2.0 A crystal structures of free and D-Phe-Phe-Arg-chloromethylketone-inhibited gingipain R reveal a 435-residue, single-polypeptide chain organized into a catalytic and an immunoglobulin-like domain. The catalytic domain is subdivided into two subdomains comprising four- and six-stranded beta-sheets sandwiched by alpha-helices. Each subdomain bears topological similarities to the p20-p10 heterodimer of caspase-1. The second subdomain harbours the Cys-His catalytic diad and a nearby Glu arranged around the S1 specificity pocket, which carries an Asp residue to enforce preference for Arg-P1 residues. This gingipain R structure is an excellent template for the rational design of drugs with a potential to cure and prevent periodontitis. Here we show the binding mode of an arginine-containing inhibitor in the active-site, thus identifying major interaction sites defining a suitable pharmacophor.
170 citations
TL;DR: Different approaches used to characterize molecular interaction in mixed monolayers, formed either by adsorption or by spreading at the air/water interface, are reviewed in this paper, where the authors present a review of these approaches.
TL;DR: Using data obtained from a magnetoelastic ribbon experiment, it is shown how a topological approach that allows for experimental error and bounded noise can be used to obtain a description of the dynamics in terms of subshift dynamics on a finite set of symbols.
Abstract: Symbolic dynamics play a central role in the description of the evolution of nonlinear systems. Yet there are few methods for determining symbolic dynamics of chaotic data. One difficulty is that the data contains random fluctuations associated with the experimental process. Using data obtained from a magnetoelastic ribbon experiment we show how a topological approach that allows for experimental error and bounded noise can be used to obtain a description of the dynamics in terms of subshift dynamics on a finite set of symbols.
TL;DR: In this article, the authors measured the spectral slopes of the production cross sections of mesons at beam energies per nucleon below and near the nucleon-nucleon threshold.
Abstract: Production cross sections of ${K}^{+}$ and ${K}^{\ensuremath{-}}$ mesons have been measured in $\mathrm{C}+\mathrm{C}$ collisions at beam energies per nucleon below and near the nucleon-nucleon threshold. At a given beam energy, the spectral slopes of the ${K}^{\ensuremath{-}}$ mesons are significantly steeper than the ones of the ${K}^{+}$ mesons. The excitation functions for ${K}^{+}$ and ${K}^{\ensuremath{-}}$ mesons nearly coincide when correcting for the threshold energy. In contrast, the ${K}^{+}$ yield exceeds the ${K}^{\ensuremath{-}}$ yield by a factor of about 100 in proton-proton collisions at beam energies near the respective nucleon-nucleon thresholds.
TL;DR: Wheel running is, at the genetic level, a largely independent axis of behaviour, and the genetic architecture of overall wheel running and its components seem conducive to increasing total distance moved without unduly increasing energy or time-related costs.
TL;DR: In this article, the IR spectra of bulk Nb2O5·nH2O and niobia supported on SiO2, Al2O3, ZrO2 and TiO2 were recorded in the fundamental and overtone NbO regions, as well as in the hydroxyl region.
Abstract: The IR spectra of bulk Nb2O5·nH2O and niobia supported on SiO2, Al2O3, ZrO2, and TiO2 were recorded in the fundamental and overtone NbO regions, as well as in the hydroxyl region, to develop a better understanding of the structural models of surface NbOx species. The coincidence of the IR and Raman fundamental NbO frequency in Nb2O5/Al2O3, Nb2O5/ZrO2, and Nb2O5/TiO2 provides the strongest evidence that the NbOx surface species (NbO fundamental at 980 cm-1) is present as a mono-oxo moiety. The IR and Raman band positions would not be coincident for a di-oxo species. This conclusion is further supported by the presence of only a single overtone at ∼1960 cm-1 (2 × 980 cm-1) in Nb2O5/ZrO2 and Nb2O5/TiO2 and the presence of the most intense overtone at 1966 cm-1 in Nb2O5/Al2O3. Lower frequency IR fundamentals at 880 cm-1 (low loading) and 935 cm-1 (high loading) are also seen in Nb2O5/ZrO2, and the IR overtone region of Nb2O5/Al2O3 exhibited weak bands at ∼1870 cm-1 (935 cm-1 overtone) and 1914 cm-1 (935 + 980...
TL;DR: In men with hypercholesterolemia, lowering serum cholesterol level by a three-month simvastatin treatment is accompanied by a marked reduction of thrombin generation both at basal conditions in venous blood and after activation of hemostasis by microvascular injury.
TL;DR: There is strong evidence that oxidative stress occurs as an early phenomenon in pancreatic tissue in the course of caerulein-induced acute pancreatitis, and results of well-designed clinical trials should finally evaluate the importance of oxidative stress-oriented treatment in acute Pancreatitis in humans.
TL;DR: The association between ambient pollutants and poorer gain of pulmonary volumes in children living in more polluted areas suggests that air pollution in the residence area may be a part of the causal chain of reactions leading to retardation in pulmonary function growth during the preadolescent years.
Abstract: The main purpose of our study was to assess the effect of low concentrations of ambient air pollution on lung function growth in preadolescent children. We accounted for height velocity over the follow-up period and also for other possible confounders such as baseline anthropometric and physiologic characteristics of children. In addition to outdoor air pollution, we considered the possible effects of social class and exposure to indoor pollutants such as gas stove fumes or environmental tobacco smoke. The cohort prospective study was carried out in 1,001 preadolescent children from two areas of Krakow, Poland, that differed in ambient air pollutants. In the city center (higher pollution area), the mean annual level [+/- standard deviation (SD)] of suspended particulate matter was 52.6 +/- 53.98 microg/m(3) and that of SO(2) was 43.87 +/- 32.69 microg/m(3); the corresponding values in the control area were 33.23 +/- 35.99 microg/m(3) and 31.77 +/- 21.93 microg/m(3). Mean lung function growth rate adjusted to height velocity and lung function level at the study entry was significantly lower in boys and girls living in the more polluted areas. Also, the proportion of children with the slower lung function growth (SLFG) was higher in the children from the more polluted area of the city. The analysis completed in the group of children after the exclusion of asthmatic subjects and those with asthmalike symptoms confirmed that, in boys, odds ratios (ORs) for SLFG [forced vital capacity (FVC)] and air pollution after adjustment to baseline FVC, height, and growth rate was significant [OR = 2.15; 95% confidence interval (CI), 1.25-3. 69)]. The analysis also confirmed that for SLFG(FEV(1)) the OR was 1. 90 (CI, 1.12-3.25). The corresponding OR values in girls were insignificant (OR = 1.50; CI, 0.84-2.68 and OR = 1.39; CI, 0.78-2. 44). The association between ambient pollutants and poorer gain of pulmonary volumes in children living in more polluted areas suggests that air pollution in the residence area may be a part of the causal chain of reactions leading to retardation in pulmonary function growth during the preadolescent years.
TL;DR: In this paper, the authors characterize testing sets for properness of polynomial mappings and study the set of points at which such mappings are not proper and give a proof of the complementary conjecture of McKay and Wang.
Abstract: In this paper we characterize testing sets for properness of polynomial mappings \(f:\mathbb{C}^n\rightarrow\mathbb{C}^m\). We also study the set of points at which such mappings are not proper. As the first application we give a proof of the Complementary Conjecture of McKay and Wang (Conjecture 12 in [16]). The second application is an answer to the problem of Kraft- Russell about a characterization of \(\mathbb{C}^n.\) The third application is (given in [13]) a solution of the Problem of Van den Essen and Shpilrain about endomorphism of the ring \(\mathbb{C}[x_1,...,x_n].\) The fourth application is a theorem about extensions of affine varieties.
TL;DR: In this article, the Coulomb dissociation of a proton at 254 MeV/nucleon using a large-acceptance focusing spectrometer was measured and the astrophysical 0.25-2.78-factor was derived.
Abstract: We have measured the Coulomb dissociation of ${}^{8}\mathrm{B}$ into ${}^{7}\mathrm{Be}$ and a proton at 254 MeV/nucleon using a large-acceptance focusing spectrometer. The astrophysical ${S}_{17}$-factor for the ${}^{7}\mathrm{Be}(p,\ensuremath{\gamma}{)}^{8}\mathrm{B}$ reaction at ${E}_{\mathrm{c}.\mathrm{m}.}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0.25--2.78\mathrm{MeV}$ is deduced yielding ${S}_{17}(0)\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}20.6\ifmmode\pm\else\textpm\fi{}1.2$ (expt) $\ifmmode\pm\else\textpm\fi{}1.0(\mathrm{theor})\phantom{\rule{0ex}{0ex}}\mathrm{eV}\mathrm{b}$. This result agrees with the presently adopted zero-energy ${S}_{17}$-factor obtained in direct-reaction measurements and with the results of other Coulomb-dissociation studies performed at 46.5 and 51.2 MeV/nucleon.
TL;DR: It is concluded that prostaglandins generated by both cyclooxygenase-1 and cyclo oxygenogenase-2 contribute to the healing of gastric lesions induced by ischemia-reperfusion.
TL;DR: The need for clear distinctions between individual variation, skewness, asymmetric competition and monopolization of resources is discussed in this paper, since these concepts are fundamental to understanding population stability.
Journal Article•
TL;DR: It is found that, after maturation, it is optimal to grow either over several years (if the animals age in the sense that their mortality increases with age) or asymptotically (if there is no ageing).
Abstract: Optimal allocation of energy to growth and reproduction was studied with a dynamic optimization method for long-lived animals inhabiting a seasonal environment. We found that, after maturation, it is optimal to grow either over several years (if the animals age in the sense that their mortality increases with age) or asymptotically (if there is no ageing). Asymptotic growth can be well approximated with BertalanVy’s equation, even if the animals are able to grow to inWnity. This is because it is optimal to allocate an increasing proportion of surplus energy to reproduction year after year following maturation. Age at Wrst reproduction depends on mortality in both favourable and unfavourable seasons, and also depends on the favourable season length ‐ it is optimal to mature early when mortality is high in either season or the season is short. Size at maturity depends additionally on the parameters of the equation describing the size-dependence of the production rate. When mortality in the unfavourable season is high compared to mortality in the favourable season, a large part of growth is realized after maturation. The model qualitatively explains growth patterns and life histories in Wsh, reptiles, amphibians and some long-lived invertebrates which grow after maturation. To understand better the diversity of life histories, Weld biologists working on such animals should focus on diVerences in the ageing rate, favourable season length, mortality rates in both seasons and the size-dependence of production rate. Optimization models based on the allocation principle are promising tools to integrate these kinds of data.
TL;DR: The production of prolyl tripeptidyl peptidase may contribute to the pathogenesis of periodontal tissue destruction through the mutual interaction of this enzyme, host and bacterial collagenases, and dipeptido peptidases in the degradation of collagen during the course of infection.
TL;DR: These different antidepressant therapies induced an elevation of the hippocampal zinc concentration, which indicates a significant role of zinc in the mechanism of antidepressant therapy.
Abstract: We have studied the effect of chronic treatment with imipramine, citalopram and electroconvulsive shock (ECS) on serum and brain zinc levels in rats. Chronic treatment with citalopram (but not with imipramine or ECS) significantly (approx 20%) increased the serum zinc level. Chronic treatment with both drugs slightly (by approx 10%) increase the zinc level in the hippocampus and slightly decreased it in the cortex, cerebellum and basal forebrain. Calculation of the ratio hippocampus/brain region within each group demonstrated a significantly (approx 20%) higher value after treatment with either imipramine or citalopram. Moreover, chronic ECS induced a significant increase (by 30%) in the zinc level in the hippocampus and also a slight increase (by 11–15%) in the other brain regions. Thus, these different antidepressant therapies induced an elevation of the hippocampal zinc concentration, which indicates a significant role of zinc in the mechanism of antidepressant therapy.
TL;DR: Deregulation of the cytokine network is an important adaptation of pathogenic bacteria to modulate and evade a host immune response and degradation of IL-6 by gingipains may represent an additional mechanism which influences the balance between pro- and anti-inflammatory reactions at distal versus proximal sites from the periodontal plaque.
TL;DR: Exogenous leptin or that released endogenously by CCK or meal exerts a potent gastroprotective action depending upon vagal activity, and involving hyperemia probably mediated by NO and sensory nerves but unrelated to endogenous prostaglandins.
TL;DR: In this paper, the authors show that the density of topological defects is drastically suppressed as the velocity with which the quench propagates becomes smaller than the speed at which the front of the broken symmetry phase spreads.
Abstract: We show that, in second-order phase transformations induced by an inhomogeneous quench, the density of topological defects is drastically suppressed as the velocity with which the quench propagates becomes smaller than the speed at which the front of the broken symmetry phase spreads. The velocity of the broken symmetry phase front is approximately given by the ratio of the healing length to relaxation time at freeze-out, that is at the instant when the critical slowing down results in a transition from the adiabatic to the impulse behavior in the order parameter. Experimental implications are briefly discussed.
TL;DR: Although the concept of biomagnification, an increase in the concentration of anthropogenic pollutants along trophic chains, has been applied to many chemicals more recent studies have shown that it does not hold true as a general rule at least for metals.
Abstract: Although the concept of biomagnification, that is, an increase in the concentration of anthropogenic pollutants along trophic chains, has been applied to many chemicals (e.g., Gilles et al., 1973; Price et al, 1974) more recent studies have shown that it does not hold true as a general rule at least for metals (e.g., Beyer, 1986; van Straalen and van Wensem, 1986; Laskowski, 1991). A number of authors have suggested that for metals species-specific differences in assimilation and excretion efficiencies are more important than trophic position (Beyer, 1986; van Straalen and van Wensem, 1986; Grodzinska et al., 1987; Laskowski and Maryanski, 1993). Among terrestrial invertebrates, ground beetles are a particularly good example. Being in most cases second-order consumers they are at least potentially exposed to increased concentrations of metals in their diet, yet at the same time as a group of invertebrates with the lowest metal concentrations (Butovsky, 1997). This may be due to efficient decontamination processes such as removal of whole degenerated cells, exocytosis, and extrusion of metal-containing vesicles into the lumen of the digestive tract (Hopkin, 1989). In fact, Janssen (1991) showed that a carabid, Notiophilus biguttatus exhibits low accumulation rate and high excretion rate of cadmium.