julilili42/papers huggingface dataset:
Asteroseismological constraints on the coolest GW Virginis variable star (PG 1159-type) PG 0122+200
2007-09-24

\\n Aims.We present an asteroseismological study of\\n<ext-link ext-link-type="aoi">PG 0122+200</ext-link>, the coolest known pulsating PG 1159 (GW Vir)\\nstar. Our results are based on an augmented set of the full PG 1159\\nevolutionary models recently presented by Miller Bertolami &amp; Althaus\\n(2006).\\n Methods.We perform extensive computations of adiabatic g-mode\\npulsation periods on PG 1159 evolutionary models with stellar masses\\nranging from 0.530 to 0.741 . These models take into\\naccount the complete evolution of progenitor stars, through the\\nthermally pulsing asymptotic giant branch phase and born-again episode. \\nWe constrain the stellar mass of <ext-link ext-link-type="aoi">PG 0122+200</ext-link> by comparing the observed period spacing with the\\nasymptotic period spacing and with the average of the computed period\\nspacings. We also employ the individual observed periods to find a\\nrepresentative seismological model for <ext-link ext-link-type="aoi">PG 0122+200</ext-link>.\\n Results.We derive a stellar mass of 0.626 from a comparison between the observed period\\nspacing and the computed asymptotic period spacing, and a stellar mass\\nof 0.567 by comparing the observed period spacing with the\\naverage of the computed period spacing. We also find, on the basis of\\na period-fit procedure, an asteroseismological model representative of\\n<ext-link ext-link-type="aoi">PG 0122+200</ext-link> that is able to reproduce the observed period pattern with an\\naverage of the period differences of = 0.88 s and a root-mean-square residual of = 1.27 s. The model has an effective temperature = 81 500 K, a stellar mass = 0.556 , a surface\\ngravity log g = 7.65, a stellar luminosity and radius of\\n = 1.14 and = -1.73,\\nrespectively, and a He-rich envelope thickness of Menv = 1.9 10-2 . We derive a seismic distance d ~ 614 pc and a parallax π ~ 1.6 mas. The results of the period-fit analysis carried out in this work suggest that the asteroseismological\\nmass of <ext-link ext-link-type="aoi">PG 0122+200</ext-link> could be ~6-20% lower than hitherto thought, and\\nin closer agreement (to within ~5%) with the spectroscopic\\nmass. This result suggests that a reasonable consistency between the\\nstellar mass values obtained from spectroscopy and asteroseismology\\ncan be expected when detailed PG 1159 evolutionary models are\\nconsidered.\\n
RGMa inhibits neurite outgrowth of neuronal progenitors from murine enteric nervous system via the neogenin receptor in vitro
2007-09-24

Abstract The enteric nervous system (ENS) in vertebrate embryos is formed by neural crest‐derived cells. During development, these cells undergo extensive migration from the vagal and sacral regions to colonize the entire gut, where they differentiate into neurons and glial cells. Guidance molecules like netrins, semaphorins, slits, and ephrins are known to be involved in neuronal migration and axon guidance. In the CNS, the repulsive guidance molecule (RGMa) has been implicated in neuronal differentiation, migration, and apoptosis. Recently, we described the expression of the subtypes RGMa and RGMb and their receptor neogenin during murine gut development. In the present study, we investigated the influence of RGMa on neurosphere cultures derived from fetal ENS. In functional in vitro assays, RGMa strongly inhibited neurite outgrowth of differentiating progenitors via the receptor neogenin. The repulsive effect of RGMa on processes of differentiated enteric neural progenitors could be demonstrated by collapse assay. The influence of the RGM receptor on ENS was also analyzed in neogenin knockout mice. In the adult large intestine of mutants we observed disturbed ganglia formation in the myenteric plexus. Our data indicate that RGMa may be involved in differentiation processes of enteric neurons in the murine gut.
The classical fields : structural features of the real and rational numbers
2007-09-24

The classical fields are the real, rational, complex and p-adic numbers. Each of these fields comprises several intimately interwoven algebraical and topological structures. This comprehensive volume analyzes the interaction and interdependencies of these different aspects. The real and rational numbers are examined additionally with respect to their orderings, and these fields are compared to their non-standard counterparts. Typical substructures and quotients, relevant automorphism groups and many counterexamples are described. Also discussed are completion procedures of chains and of ordered and topological groups, with applications to classical fields. The p-adic numbers are placed in the context of general topological fields: absolute values, valuations and the corresponding topologies are studied, and the classification of all locally compact fields and skew fields is presented. Exercises are provided with hints and solutions at the end of the book. An appendix reviews ordinals and cardinals, duality theory of locally compact Abelian groups and various constructions of fields
THE EVOLUTION OF DIOECY, HETERODICHOGAMY, AND LABILE SEX EXPRESSION IN ACER
2007-09-25

The northern hemisphere tree genus Acer comprises 124 species, most of them monoecious, but 13 dioecious. The monoecious species flower dichogamously, duodichogamously (male, female, male), or in some species heterodichogamously (two morphs that each produce male and female flowers but at reciprocal times). Dioecious species cannot engage in these temporal strategies. Using a phylogeny for 66 species and subspecies obtained from 6600 nucleotides of chloroplast introns, spacers, and a protein-coding gene, we address the hypothesis (Pannell and Verdú, Evolution 60: 660-673. 2006) that dioecy evolved from heterodichogamy. This hypothesis was based on phylogenetic analyses (Gleiser and Verdú, New Phytol. 165: 633-640. 2005) that included 29-39 species of Acer coded for five sexual strategies (duodichogamous monoecy, heterodichogamous androdioecy, heterodichogamous trioecy, dichogamous subdioecy, and dioecy) treated as ordered states or as a single continuous variable. When reviewing the basis for these scorings, we found errors that together with the small taxon sample, cast doubt on the earlier inferences. Based on published studies, we coded 56 species of Acer for four sexual strategies, dioecy, monoecy with dichogamous or duodichogamous flowering, monoecy with heterodichogamous flowering, or labile sex expression, in which individuals reverse their sex allocation depending on environment-phenotype interactions. Using Bayesian character mapping, we infer an average of 15 transformations, a third of them involving changes from monoecy-cum-duodichogamy to dioecy; less frequent were changes from this strategy to heterodichogamy; dioecy rarely reverts to other sexual systems. Contra the earlier inferences, we found no switches between heterodichogamy and dioecy. Unexpectedly, most of the species with labile sex expression are grouped together, suggesting that phenotypic plasticity in Acer may be a heritable sexual strategy. Because of the complex flowering phenologies, however, a concern remains that monoecy in Acer might not always be distinguishable from labile sex expression, which needs to be addressed by long-term monitoring of monoecious trees. The 13 dioecious species occur in phylogenetically disparate clades that date back to the Late Eocene and Oligocene, judging from a fossil-calibrated relaxed molecular clock.
MR‐guided radiofrequency ablation in a 0.2‐T open MR system: Technical success and technique effectiveness in 100 liver tumors
2007-09-25

Abstract Purpose To evaluate the feasibility and technique effectiveness of magnetic resonance (MR)‐guided radiofrequency (RF) ablation of hepatic malignancies. Materials and Methods In 64 patients, 100 primary ( N = 19) or secondary ( N = 81) liver tumors (mean diameter = 24.7 mm; range = 4–60 mm) were treated with 87 sessions of MR‐guided RF ablation. The entire ablation procedure was carried out at an 0.2‐T open MR system by using MR‐compatible internally cooled electrodes. T2‐weighted turbo spin echo sequences (TR/TE = 3500 msec/110 msec) were used to monitor thermally induced coagulation. Technique effectiveness was assessed four months after the last RF ablation by dynamic MR imaging at 1.5‐T. Results MR‐guided RF ablation procedures were technical successful in 85 of 87 (97.7%) assessed at the end of each session. Complete coagulation was intended in 99 of 100 tumors. Technique effectiveness was observed in 92 of 99 (92.9%) of these tumors. To achieve complete coagulation 82 of 92 (89.1%) tumors required a single session. T2‐weighted sequences were accurate to monitor the extent of coagulation and were supportive to guide overlapping ablation. There were two of 87 (2.3%) major and seven of 87 (8.0%) minor complications. Conclusion MR‐guided RF ablation is a safe and effective therapy in the treatment of hepatic malignancies. MR imaging offers an accurate monitoring of thermally‐induced coagulation, thus enabling complete tumor coagulation in a single session. J. Magn. Reson. Imaging 2007;26:1043–1052. © 2007 Wiley‐Liss, Inc.
Emergence of increasing linezolid-resistance in enterococci in a post-outbreak situation with vancomycin-resistantEnterococcus faecium
2007-09-25

SUMMARY During 2004 and at the start of 2005 a university hospital in Southwest Germany was affected by an extensive outbreak of vancomycin-resistant Enterococcus faecium (VRE). Although the outbreak was contained, linezolid-resistant enterococci emerged during and after the outbreak as the usage of linezolid became more common. Linezolid resistance was no longer limited to VRE. Nosocomial spread of linezolid-resistant but vancomycin-susceptible E. faecium was detected and these strains also emerged in patients without prior drug exposure. Linezolid should therefore be used with caution and the susceptibility of isolates monitored over time. Isolation precautions and screening of contacts should be considered to avoid spread of resistant isolates.
From registry to quality management: the German Cystic Fibrosis Quality Assessment project 1995–2006
2007-09-26

Since 1995, the German Cystic Fibrosis Quality Assessment project has collected demographic data and outcome parameters. It aims to develop tools for quality management. The basic data of 6,835 patients has been collected annually by 93 centres. Weight for height and body mass index (BMI) indicated nutritional status, and forced expiratory volume in one second (FEV 1 ) served as the central respiratory parameter. Data on mortality and survival were calculated. The mean age of all patients has increased from 13.9 yrs in 1995 to 17.7 yrs in 2005, and the percentage of adult patients has increased from 28.4 to 43.4%. Benchmarking diagrams and centre reports indicated considerable differences between the centres. The achievement of basic aims at the age of 6, 12 and 18 yrs indicated a positive development in 1995 to 2005. In 2005, median age at death was 23.7 yrs and the median cumulative survival was 37.4 yrs. Mortality correlated with a BMI &lt;19 kg·m −2 and an FEV 1 &lt;80%. No sex gap in mortality was detected. “Learning from the best” is now possible. Further improvements in the system of cystic fibrosis care are required, such as: defining alarm signals for early treatment; involvement of patients and their families in quality management; auditing; benchmarking; and in-house training.
The ’t Hooft loop in the Hamiltonian approach to Yang-Mills theory in Coulomb gauge
2007-09-26

The spatial 't Hooft loop, which is a disorder parameter dual to the temporal Wilson loop, is calculated using the nonperturbative Yang-Mills vacuum wave functional determined previously by a variational solution of the Yang-Mills Schroedinger equation in Coulomb gauge. It is shown, that this wave functional yields indeed a perimeter law for large spatial 't Hooft loops signaling confinement.
Flame spray pyrolysis based nano-structured functional metal oxide layers for gas sensing applications
2007-09-26

The contribution presents the results obtained in the last years by applying an established aerosol based production technology for metal oxide nanoparticles mainly used in catalysis and filler materials, the so called flame spray pyrolysis (FSP), to gas sensor fabrication. The final achievement of this technology is a fast and clean single step process to fabricate fully functionalized multilayer sensors. This is a substantial progress as it merges the two fundamental processes of producing the sensing material and fabricating the sensing element.
2-(6-Methoxy-7H-purin-7-yl)-1-phenylethanone monohydrate
2007-09-26

The crystal structure of the title compound, C14H12N4O2·H2O, was determined in the course of our studies of the synthesis and optimization of 7-aryl-7H-purines as inhibitors of the vascular endothelial growth factor receptor (VEGF-R), c-Jun NH2-terminal protein kinase 3 (JNK3) and the p38α mitogen-activated protein kinase (MAPK). In the title compound, two molecules are associated with each other through O—H⋯N hydrogen bonds to different N atoms in the purine ring system. The compound was prepared via a regioselective synthesis using the methyl(aqua)cobaloxime complex, CH3Co(DH)2OH2, as a temporary auxiliary. The X-ray crystallographic results confirmed the regioselective N-7 alkylation of this molecule.
Hunting the active species in gas sensing processes: operando studies on tin dioxide-based sensors
2007-09-26

The understanding of the gas sensing mechanism at a fundamental level implies the knowledge of the state of preadsorbed surface species. Some question marks on the commonly accepted ideas were raised by the recorded higher sensitivity of sensors to CO in nitrogen and by the fact that the combustion of CO was observed in air and in humid nitrogen. These facts question the monopoly of oxygen ions as the reaction partners for CO and they were the driving force for thereby presented investigations. DRIFT Spectroscopy and resistance measurements have been simultaneously applied to discriminate between the species that are actively taking part in the sensing processes and spectators. The comparison between the different sensors has been focused on verifying whether the observed phenomena are general or whether they depend on the technology. It was observed that for SnO<sub>2</sub> sensors, the reaction of oxygen, with water results in the formation of terminal hydroxyls and the release of an electron to the conduction band. It indicates that water compete with reducing gases for the oxygen ions. This phenomenon was independent of the technology and thus it could be SnO<sub>2</sub> characteristic. It was shown that CO reacts preferentially with ionosorbed oxygen at the surface of tin dioxide. In the case of lack of oxygen different scenarios are possibly dependent on hydration state of the surface.
Identification of CD46 Binding Sites within the Adenovirus Serotype 35 Fiber Knob
2007-09-27

ABSTRACT Species B human adenoviruses (Ads) are often associated with fatal illnesses in immunocompromised individuals. Recently, species B Ads, most of which use the ubiquitously expressed complement regulatory protein CD46 as a primary attachment receptor, have gained interest for use as gene therapy vectors. In this study, we focused on species B Ad serotype 35 (Ad35), whose trimeric fiber knob domain binds to three CD46 molecules with a K D (equilibrium dissociation constant) of 15.5 nM. To study the Ad35 knob-CD46 interaction, we generated an expression library of Ad35 knobs with random mutations and screened it for CD46 binding. We identified four critical residues (Phe242, Arg279, Ser282, and Glu302) which, when mutated, ablated Ad35 knob binding to CD46 without affecting knob trimerization. The functional importance of the identified residues was validated in surface plasmon resonance and competition binding studies. To model the Ad35 knob-CD46 interaction, we resolved the Ad35 knob structure at 2-Å resolution by X-ray crystallography and overlaid it onto the existing structure for Ad11-CD46 interaction. According to our model, all identified Ad35 residues are in regions that interact with CD46, whereby one CD46 molecule binds between two knob monomers. This mode of interaction might have potential consequences for CD46 signaling and intracellular trafficking of Ad35. Our findings are also fundamental for better characterization of species B Ads and design of antiviral drugs, as well as for application of species B Ads as in vivo and in vitro gene transfer vectors.
Are MAP Kinases Drug Targets? Yes, but Difficult Ones
2007-09-27

Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
A 7-dimethylallyltryptophan synthase from Aspergillus fumigatus: overproduction, purification and biochemical characterization
2007-09-28

A putative prenyltransferase gene, Afu3g12930, was identified in the genome sequence of Aspergillus fumigatus. EAL92290, encoded by Afu3g12930, consists of 472 aa, with a molecular mass of about 53 kDa. The coding sequence of Afu3g12930 was cloned in pQE60, and overexpressed in Escherichia coli. The soluble His(6)-fusion protein was purified to apparent homogeneity, and characterized biochemically. The enzyme was found to catalyse the prenylation of Trp at the C-7 position of the indole moiety, in the presence of dimethylallyl diphosphate (DMAPP); therefore, it functions as a 7-dimethylallyltryptophan synthase (7-DMATS). The structure of the enzymic product was elucidated by NMR and MS analysis. K(m) values were 67 microM for DMAPP, and 137 microM for l-Trp. Geranyl diphosphate was not accepted as prenyl donor, while Trp-containing dipeptides were found to be aromatic substrates of 7-DMATS. 7-DMATS did not need divalent metal ions for its enzymic reaction, although Ca(2+) enhanced the reaction velocity slightly. The enzyme is the second dimethylallyltryptophan synthase identified in A. fumigatus. Interestingly, it shares a sequence identity of only 31 % at the amino acid level with another known dimethylallyltryptophan synthase, FgaPT2, from the same fungus; FgaPT2 prenylates l-Trp at the C-4 position of the indole ring. Afu3g12930 belongs to a putative biosynthetic gene cluster consisting of eight genes. Orthologous clusters were also identified in the genome sequences of Neosartorya fischeri and Aspergillus terreus. The putative roles of the genes in the cluster are discussed.
Rescue of cGMP Kinase I Knockout Mice by Smooth Muscle–Specific Expression of Either Isozyme
2007-09-28

Smooth muscle expresses the Iα and the Iβ isoforms of cGMP-dependent protein kinase I (cGKI). Inactivation of the murine cGKI gene prkg1 leads to multiple phenotypes and premature death at ≈6 weeks. We reconstituted mice with the cGKIα or -Iβ isozyme to test which isozyme was needed to support basic smooth muscle functions. Mice were generated by gene targeting. The cGKIα or the -Iβ coding sequences were placed under the control of the SM22α promoter to express either isoform selectively in smooth muscle cells (SM-Iα or SM-Iβ transgene). To generate smooth muscle–specific cGKIα or cGKIβ rescue mice, the SM-Iα or SM-Iβ transgenes were crossed on a cGKI −/− genetic background. The levels of cGKIα or -Iβ expression were comparable to endogenous cGKI expression in wild-type aortic and intestinal smooth muscles. In cGKIα or -Iβ rescue mice, expression of the isozymes was not detectable in non–smooth muscle tissues and cells. Median survival time of the Iα and Iβ rescue mice was 52 weeks. Both isozymes mediated the 8-bromo-cGMP–induced relaxation of precontracted jejunum and aorta muscle strips. Activation of both isozymes reduced hormone- or K + -induced [Ca 2+ ] i levels. The cGKIα and cGKIβ rescue mice did not show a significant difference in intestinal passage time of BaSO 4 in comparison with wild-type animals. Telemetric blood pressure measurements in conscious freely moving animals did not show differences between rescues and control mice in basal blood pressure and its regulation by DETA-NO, sodium nitroprusside, carbachol, or Y-27632. These results show that cGKI in smooth muscle is essential and that either cGKI isozyme alone can rescue basic vascular and intestinal smooth muscle functions.
The Replicon Initiation Burst Released by Reoxygenation of Hypoxic T24 Cells is Accompanied by Changes of MCM2 and Cdc7
2007-09-30

Although MCM2 is obviously important for the initiation of eukaryotic DNA replication, its role in O2 dependent regulation of replicon initiation is poorly understood. In this report, I analysed the changes of MCM2 during the transition from hypoxically suppressed replicon initiation to the burst of initiation triggered by reoxygenation in T24 cells. A high level of chromatin bound and nucleosolic MCM2 was found under the hypoxic replicon arrest. In contrast low cytosolic MCM2 was noticed. Recovery of O2 induced phosphorylation and diminution of chromatin bound MCM2, whereas cytosolic MCM2 increased. The level of chromatin bound Cdc7 did not change significantly upon reoxygenation. However, after reoxygenation, significant phosphorylation of Cdc7 and an increase of coimmunoprecipitation with its substrate (MCM2) were observed. This provides a hint that reoxygenation may promote the kinase activity of Cdc7. These changes might be the critical factors in O2 dependent regulation of replicon initiation. Moreover, phosphorylation of Cdc7 by Cdk2 can be observed in vitro, but seems to fail to regulate the level of chromatin bound Cdc7 as well as the changes of MCM2 in response to reoxygenation of hypoxically suppressed cells.
Mechanisms and Significance of Cell Volume Regulation
2007-10-01

Survival of human and animal cells requires avoidance of excessive alterations of cell volume. The osmolarity amassed by cellular accumulation of organic substances must be compensated by lowering cytosolic ion concentrations. The Na+/K+ ATPase extrudes Na+ in exchange for K+, which can permeate the cell membrane through K+ channels. K+ exit generates a cell-negative potential difference across the cell membrane, driving the exit of anions such as Cl-. The low cytosolic Cl- concentrations counterbalance the excess cellular osmolarity by organic substances. Cell volume regulation following cell swelling involves releasing ions through activation of K+ channels and/or anion channels, KCl-cotransport, or parallel activation of K+/H+ exchange and Cl-/HCO3- exchange. Cell volume regulation following cell shrinkage involves accumulation of ions through activation of Na+,K+,2Cl- cotransport, Na+/H+ exchange in parallel to Cl-/HCO3- exchange, or Na+ channels. The Na+ taken up is extruded by the Na+/K+ ATPase in exchange for K+. Shrunken cells further accumulate organic osmolytes such as sorbitol and glycerophosphorylcholine, and monomeric amino acids by altered metabolism and myoinositol (inositol), betaine, taurine, and amino acids by Na+ coupled transport. They release osmolytes during cell swelling. Challenges of cell volume homeostasis include transport, hormones, transmitters, and drugs. Moreover, alterations of cell volume participate in the machinery regulating cell proliferation and apoptotic cell death. Deranged cell volume regulation significantly contributes to the pathophysiology of several disorders such as liver insufficiency, diabetic ketoacidosis, hypercatabolism, fibrosing disease, sickle cell anemia, and infection.