julilili42/papers huggingface dataset:
Neural Cell Adhesion Molecule, a New Cytoadhesion Receptor forPlasmodium falciparum-Infected Erythrocytes Capable of Aggregation
2007-05-08

ABSTRACT The cytoadhesion of Plasmodium falciparum -infected erythrocytes (IEs) to the endothelial cells lining the microvasculature, clogging the microvessels of various organs, is a key event in the pathogenesis of certain severe forms of malaria, such as cerebral malaria and pulmonary edema. Studies aiming to identify possible correlations between the severity of clinical cases and the presence of particular cytoadhesion phenotypes have been largely unsuccessful. One of the possible reasons for this failure is that some of the key receptors and/or mechanisms involved have yet to be identified. By combining IE selection, cell transfection, and adhesion inhibition assays, we identified a new cytoadhesion receptor, neural cell adhesion molecule (NCAM). NCAM is a member of the immunoglobulin superfamily and has nonpolysialylated and polysialylated isoforms, the latter being rare in adults. The nonpolysialylated form is present on the surfaces of endothelial cells in the microvessels of various organs in which IE sequestration occurs. We found that multiphenotypic IEs interacted with nonpolysialylated NCAM and with another, as yet unidentified receptor. These IEs also displayed cytoadhesion in flow conditions, presenting the unique ability to form adherent macroaggregates composed of hundreds of IEs. These features may act as virulence factors, increasing the capacity of IEs to clog microvessels via receptor synergy and macroaggregate formation, thereby facilitating the pathogenesis of severe forms of malaria.
Genetic variation within the APPL locus is not associated with metabolic or inflammatory traits in a healthy White population
2007-05-08

Abstract Aims APPL1 (adaptor protein containing PH domain, PTB domain and leucine zipper motif 1) is the first identified cytosolic protein that directly binds to adiponectin receptors and mediates cellular responses to adiponectin. We set out to determine whether genetic variation within the APPL locus (encoding APPL1) contributes to insulin resistance, changes in lipid metabolism or inflammatory parameters in a healthy White population. Methods We genotyped 640 healthy subjects with and without a family history of diabetes for the four single nucleotide polymorphisms (SNPs) rs6774584, rs3087684, rs17791685 and rs528035 and performed correlational analyses with metabolic and inflammatory traits. Results SNPs rs6774584, rs3087684, rs17791685 and rs528035 are representative of the four blocks of high linkage disequilibrium covering a 78‐kb genomic locus that harbours the APPL gene. None of these SNPs correlated with anthropometric data (gender, age, body mass index, body fat, waist–hip ratio) or with family history of diabetes. Furthermore, no correlations were found with parameters of insulin sensitivity or insulin secretion. None of the SNPs was correlated with ectopic lipid content or with plasma lipids (non‐esterified fatty acids, glycerol, triglycerides, total cholesterol, high‐density lipoprotein‐, low‐density lipoprotein‐cholesterol). Moreover, no correlations were detected with leucocyte measures or plasma concentrations of C‐reactive protein, monocyte chemoattractant protein 1, interleukin 6 or tumour necrosis factor‐alpha. Finally, diplotypes derived from these SNPs did not reveal correlations with insulin sensitivity, insulin secretion, lipid measures or inflammatory parameters either. Conclusions We conclude that genetic variation within the APPL locus may not play a major role in the development of prediabetes phenotypes.
Interaction of nitrogen nutrition and salinity in Grey poplar (Populus tremula × alba)
2007-05-09

ABSTRACT Salinity represents an increasing environmental problem in managed ecosystems. Populus spp. is widely used for wood production by short‐rotation forestry in fertilized plantations and can be grown on saline soil. Because N fertilization plays an important role in salt tolerance, we analysed Grey poplar ( Populus tremula × alba , syn. Populus canescens ) grown with either 1 mM nitrate or ammonium subjected to moderate 75 mM NaCl. The impact of N nutrition on amelioration of salt tolerance was analysed on different levels of N metabolism such as N uptake, assimilation and N (total N, proteins and amino compounds) accumulation. Na concentration increased in all tissues over time of salt exposure. The N nutrition‐dependent effects of salt exposure were more intensive in roots than in leaves. Application of salt reduced root increment as well as stem height increase and, at the same time, increased the concentration of total amino compounds more intensively in roots of ammonium‐fed plants. In leaves, salt treatment increased concentrations of total N more intensively in nitrate‐fed plants and concentrations of amino compounds independently of N nutrition. The major changes in N metabolism of Grey poplar exposed to moderate salt concentrations were detected in the significant increase of amino acid concentrations. The present results indicate that N metabolism of Grey poplar exposed to salt performed better when the plants were fed with nitrate instead of ammonium as sole N source. Therefore, nitrate fertilization of poplar plantations grown on saline soil should be preferred.
Quantum top inside a Bose-Einstein-condensate Josephson junction
2007-05-09

We consider an atomic quantum dot confined between two weakly-coupled\\nBose-Einstein condensates, where the dot serves as an additional tunneling\\nchannel. It is shown that the thus-embedded atomic quantum dot is a pseudospin\\nsubject to an external torque, and therefore equivalent to a quantum top. We\\ndemonstrate by numerical analysis of the time-dependent coupled evolution\\nequations that this microscopic quantum top is very sensitive to any deviation\\nfrom linear oscillatory behavior of the condensates. For sufficiently strong\\ndot-condensate coupling, the atomic quantum dot can induce or modify the\\ntunneling between the macroscopic condensates in the two wells.\\n
A Comprehensive Model for the Cellular Uptake of Cationic Cell‐penetrating Peptides
2007-05-10

The plasma membrane represents an impermeable barrier for most macromolecules. Still some proteins and so‐called cell‐penetrating peptides enter cells efficiently. It has been shown that endocytosis contributes to the import of these molecules. However, conflicting results have been obtained concerning the nature of the endocytic process. In addition, there have been new findings for an endocytosis‐independent cellular entry. In this study, we provide evidence that the Antennapedia‐homeodomain‐derived antennapedia (Antp) peptide, nona‐arginine and the HIV‐1 Tat‐protein‐derived Tat peptide simultaneously use three endocytic pathways: macropinocytosis, clathrin‐mediated endocytosis and caveolae/lipid‐raft‐mediated endocytosis. Antennapedia differs from Tat and R9 by the extent by which the different import mechanisms contribute to uptake. Moreover, at higher concentrations, uptake occurs by a mechanism that originates from spatially restricted sites of the plasma membrane and leads to a rapid cytoplasmic distribution of the peptides. Endocytic vesicles could not be detected, suggesting an endocytosis‐independent mode of uptake. Heparinase treatment of cells negatively affects this import, as does the protein kinase C inhibitor rottlerin, expression of dominant‐negative dynamin and chlorpromazine. This mechanism of uptake was observed for a panel of different cell lines. For Antp, significantly higher peptide concentrations and inhibition of endocytosis were required to induce its uptake. The relevance of these findings for import of biologically active cargos is shown.
High-resolution FUSE and HST ultraviolet spectroscopy of the white dwarf central star of Sh 2-216
2007-05-10

LS V +4621 is the DAO-type central star of the planetary nebula Sh 2-216. We perform a comprehensive spectral analysis of high-resolution, high-S/N ultraviolet observations obtained with FUSE and STIS aboard the HST as well as the optical spectrum of LS V +4621 by means of state-of-the-art NLTE model-atmosphere techniques in order to compare its photospheric properties to theoretical predictions from stellar evolution theory as well as from diffusion calculations. From the N IV - NV, O IV - O VI, Si IV - Si V, and Fe V - Fe VII ionization equilibria, we determined an effective temperature of 95 +/- 2 kK with high precision. The surface gravity is log g = 6.9 +/- 0.2. An unexplained discrepancy appears between the spectroscopic distance d = 224 +46/-58 pc and the parallax distance d = 129 +6/-5 pc of LS V +4621. For the first time, we have identified Mg IV and Ar VI absorption lines in the spectrum of a hydrogen-rich central star and determined the Mg and Ar abundances as well as the individual abundances of iron-group elements (Cr, Mn, Fe, Co, and Ni). With the realistic treatment of metal opacities up to the iron group in the model-atmosphere calculations, the so-called Balmer-line problem (found in models that neglect metal-line blanketing) vanishes. Spectral analysis by means of NLTE model atmospheres has presently arrived at a high level of sophistication, which is now hampered largely by the lack of reliable atomic data and accurate line-broadening tables. Strong efforts should be made to improve upon this situation.
Discovery of two candidate pulsar wind nebulae in very-high-energy gamma rays
2007-05-10

We present the discovery of two very-high-energy gamma-ray sources in an\\nongoing systematic search for emission above 100 GeV from pulsar wind nebulae\\nin survey data from the H.E.S.S. telescope array. Imaging Atmospheric Cherenkov\\nTelescopes are ideal tools for searching for extended emission from pulsar wind\\nnebulae in the very-high-energy regime. H.E.S.S., with its large field of view\\nof 5 degrees and high sensitivity, gives new prospects for the search for these\\nobjects. An ongoing systematic search for very-high-energy emission from\\nenergetic pulsars over the region of the Galactic plane between -60 degrees &lt; l\\n&lt; 30 degrees, -2 degrees &lt; b &lt; 2 degrees is performed. For the resulting\\ncandidates, the standard H.E.S.S. analysis was applied and a search for\\nmulti-wavelength counterparts was performed. We present the discovery of two\\nnew candidate gamma-ray pulsar wind nebulae, HESS J1718-385 and HESS J1809-193.\\nH.E.S.S. has proven to be a suitable instrument for pulsar wind nebula\\nsearches.\\n
Temperature-Induced Inversion of the Elution Order of Enantiomers in Gas Chromatography:  N-Ethoxycarbonyl Propylamides and N-Trifluoroacetyl Ethyl Esters of α-Amino Acids on Chirasil-Val-C11 and Chirasil-Dex Stationary Phases
2007-05-10

Inversion of the elution order of enantiomers caused by enthalpy-entropy compensation at the isoenantioselective temperature (Tiso) was experimentally observed by gas chromatography on the diamide-type chiral stationary phase (CSP), Chirasil-L-Val-C11, with N-ethoxycarbonyl propylamide (ECPA) derivatives of a number of alpha-amino acids. For the first time, a clear visual representation of the increase of the apparent enantioseparation factor alpha app from 1.00 to 1.08 as the temperature is raised from 120 to 170 degrees C is presented. The increase of alpha app is accompanied by a concomitant reduction of the retention factors of the enantiomers. The Tiso values were in the range from 110 to 130 degrees C depending on the nature of the alpha-amino acid. On the contrary, the Tiso values of the N(O)-trifluoroacetyl ethyl ester derivatives (TFA-Et) of the same alpha-amino acids were approximately 80 degrees higher than that of ECPA derivatives. The comprehensive thermodynamic investigation of the enantioseparation of ECPA and TFA-Et derivatives of valine and alanine using the retention increment method showed that the Delta L,D(DeltaH) difference between the diastereomeric selector-selectand associates was almost the same for ECPA and TFA-Et derivatives despite a much stronger bonded selector-selectand association taking place for the ECPA derivatives. On the other hand, the Delta L,D(DeltaS) values were found to be more negative in the case of ECPA derivatives, resulting in the unusually low values of Tiso. A temperature-dependent inversion of the elution order of enantiomers was also observed on the cyclodextrin-type CSP, Chirasil-Dex, with TFA-Et derivatives of several alpha-amino acids. The Tiso values were in the range from 20 to 170 degrees C depending on the nature of the alpha-amino acid. The results obtained demonstrate the necessity to conduct temperature-dependent studies in order to optimize the enantiomeric separation of single racemates isothermally or of mixtures of racemates in temperature-programmed runs using enantioselective GC. It is also shown that consideration of the elution order of enantiomers and the value of the apparent enantioseparation factor alpha app alone, without performing temperature-dependent measurements, can easily lead to wrong conclusions regarding the enantiorecognition mechanism.
TECHNICAL NOTES ON CPP: Amygdala cannulation alters expression of cocaine conditioned place preference and locomotion in rats
2007-05-10

ABSTRACT The effect of transient inactivation of the amygdala on expression of cocaine conditioned place preference (CPP) and locomotion was studied. We found that rats with bilateral but not unilateral amygdala cannula placement exhibited increased CPP expression during a vehicle and a cocaine test as well as increased cocaine‐induced hyper‐locomotion. We discuss the observed effects as being caused by the cannulation per se and we conclude that the applied cannulation produced an increased responsiveness of the amygdala by a yet undetermined mechanism.
Heptakis[2,3‐di‐O‐methyl‐6‐O‐(L‐valine‐tert‐butylamide‐Nα‐ylcarbonylmethyl)]‐β‐cyclodextrin: a New Multifunctional Cyclodextrin CSA for the NMR Enantiodiscrimination of Polar and Apolar Substrates
2007-05-10

Abstract Heptakis[2,3‐di‐ O ‐methyl‐6‐ O ‐( L ‐valine‐ tert ‐butylamide‐ N α ‐ylcarbonylmethyl)]‐β‐cyclodextrin with methyl groups on the secondary sites and a diamide chiral selector on the primary ones showed considerable utility as a CSA in the NMR enantiodiscrimination of a wide spectrum of amino acid derivatives, while also allowing trisubstituted allenes to be enantiodiscriminated. Enantiodiscrimination processes were investigated by Diffusion‐Ordered SpectroscopY (DOSY). (© Wiley‐VCH Verlag GmbH &amp; Co. KGaA, 69451 Weinheim, Germany, 2007)
Torsional oscillations of slowly rotating relativistic stars
2007-05-10

We study the effects of rotation on the torsional modes of oscillating relativistic stars with a solid crust. Earlier works in Newtonian theory provided estimates of the rotational corrections for the torsional modes and suggested that they should become Chandrasekhar–Friedman–Schutz unstable, even for quite low rotation rates. In this work, we study the effect of rotation in the context of general relativity using elasticity theory and in the slow-rotation approximation. We find that the Newtonian picture does not change considerably. The inclusion of relativistic effects leads only to quantitative corrections. The degeneracy of modes for different values of m is removed, and modes with l = m are shifted towards zero frequencies and become secularly unstable at stellar rotational frequencies ~20–30 Hz.
H.E.S.S. Observations of the Supernova Remnant RX J0852.0−4622: Shell‐Type Morphology and Spectrum of a Widely Extended Very High Energy Gamma‐Ray Source
2007-05-11

The shell-type supernova remnant RX J0852.0-4622 was observed with the High Energy Stereoscopic System (H.E.S.S.) of atmospheric Cerenkov telescopes between 2004 December and 2005 May for a total observation time of 33 hr, above an average gamma-ray energy threshold of 250 GeV. The angular resolution of ∼0.06° (for events triggering three or four telescopes) and the large field of view of H.E.S.S. (5° diameter) are well adapted to studying the morphology of the object in very high energy gamma rays, which exhibits a remarkably thin shell very similar to the features observed in the radio range and in X-rays. The spectral analysis of the source from 300 GeV to 20 TeV is also presented. Finally, the possible origins of the very high energy gamma-ray emission (inverse Compton scattering by electrons or the decay of neutral pions produced by proton interactions) are discussed, on the basis of morphological and spectral features obtained at different wavelengths. © 2007. The American Astronomical Society. All rights reserved.
Early efforts in modeling the incubation period of infectious diseases with an acute course of illness
2007-05-11

Abstract The incubation period of infectious diseases, the time from infection with a microorganism to onset of disease, is directly relevant to prevention and control. Since explicit models of the incubation period enhance our understanding of the spread of disease, previous classic studies were revisited, focusing on the modeling methods employed and paying particular attention to relatively unknown historical efforts. The earliest study on the incubation period of pandemic influenza was published in 1919, providing estimates of the incubation period of Spanish flu using the daily incidence on ships departing from several ports in Australia. Although the study explicitly dealt with an unknown time of exposure, the assumed periods of exposure, which had an equal probability of infection, were too long, and thus, likely resulted in slight underestimates of the incubation period. After the suggestion that the incubation period follows lognormal distribution, Japanese epidemiologists extended this assumption to estimates of the time of exposure during a point source outbreak. Although the reason why the incubation period of acute infectious diseases tends to reveal a right-skewed distribution has been explored several times, the validity of the lognormal assumption is yet to be fully clarified. At present, various different distributions are assumed, and the lack of validity in assuming lognormal distribution is particularly apparent in the case of slowly progressing diseases. The present paper indicates that (1) analysis using well-defined short periods of exposure with appropriate statistical methods is critical when the exact time of exposure is unknown, and (2) when assuming a specific distribution for the incubation period, comparisons using different distributions are needed in addition to estimations using different datasets, analyses of the determinants of incubation period, and an understanding of the underlying disease mechanisms.
Guilds of mycorrhizal fungi and their relation to trees, ericads, orchids and liverworts in a neotropical mountain rain forest
2007-05-11

Mycorrhizas of vascular plants and mycorrhiza-like associations of liverworts and hornworts are integral parts of terrestrial ecosystems, but have rarely been studied in tropical mountain rain forests. The tropical mountain rain forest area of the Reserva Biológica San Francisco in South Ecuador situated on the eastern slope of the Cordillera El Consuelo is exceptionally rich in tree species, ericads and orchids, but also in liverworts. Previous light and electron microscopical studies revealed that tree roots are well colonized by structurally diverse Glomeromycota, and that epiphytic, pleurothallid orchids form mycorrhizas with members of the Tulasnellales and the Sebacinales (Basidiomycota). Sebacinales also occurred in mycorrhizas of hemiepiphytic ericads and Tulasnellales were found in liverworts belonging to the Aneuraceae. On the basis of these findings, we hypothesized that symbiotic fungi with a broad host range created shared guilds or even fungal networks between different plant species and plant families. To test this hypothesis, molecular phylogenetic studies of the fungi associated with roots and thalli were carried out using sequences of the nuclear rDNA coding for the small subunit rRNA (nucSSU) of Glomeromycota and the large subunit rRNA (nucLSU) of Basidiomycota. Sequence analyses showed that Sebacinales and Tulasnellales were only shared within but not between ericads and orchids or between liverworts and orchids, respectively. Regarding arbuscular-mycorrhiza-forming trees, however, 18 out of 33 Glomus sequence types were shared by two to four tree species belonging to distinct families. Nearly all investigated trees shared one sequence type with another tree individual. Host range and potential shared guilds appeared to be restricted to the plant family level for Basidiomycota, but were covering diverse plant families in case of Glomeromycota. Given that the sequence types as defined here correspond to fungal species, our findings indicate potential fungal networks between trees. © 2007 Gesellschaft f�r �kologie.
Effects of cholesterol and simvastatin treatment in patients with Smith–Lemli–Opitz syndrome (SLOS)
2007-05-11

Summary Smith–Lemli–Opitz syndrome (SLOS) is a malformation syndrome caused by deficiency of 7‐dehydrocholesterol reductase catalysing the last step of cholesterol biosynthesis. This results in an accumulation of 7‐ and 8‐dehydrocholesterol (7+8–DHC) and, in most patients, a deficiency of cholesterol. Current therapy consists of dietary cholesterol supplementation, which raises plasma cholesterol levels, but clinical effects have been reported in only a few patients. Hydroxymethylglutaryl‐coenzyme A (HMG‐CoA) reductase inhibitors were shown to reduce 7+8–DHC levels and increase cholesterol concentrations in two small trials with divergent clinical outcome. This retrolective study evaluates the effects of cholesterol only and of cholesterol plus the HMG‐CoA reductase inhibitor simvastatin on plasma sterols in 39 SLOS patients and on anthropometric measures in 20 SLOS patients. Cholesterol as well as additional simvastatin decreased the plasma (7+8–DHC)/cholesterol ratio. However, the mechanism leading to the decreasing ratio was different. Whereas it was due to an increasing cholesterol concentration in the cholesterol‐only cohort, a decreasing 7+8–DHC concentration was demonstrated in the cohort receiving additional simvastatin. We could not confirm a positive effect of simvastatin treatment on anthropometric measures or behaviour, as previously reported.
Competent Optimization of Water Supply Problems under Uncertainty by Evolution Strategies
2007-05-11

The combined use of models, together with optimisation algorithms (OAs), has evolved as a crucial element in the decision making process for groundwater management. Typically, the OA iteratively runs the model, evaluates the output with respect to an objective function and, finally, identifies an optimal solution. This procedure may afford hundreds to thousands of model runs, particularly for high dimensional, non-linear and non-convex optimisation problems. Our research focuses on tactics to minimize the required number of simulations and thus the computational time, without compromising the performance of the OA. Otherwise CPU demanding models will hardly be applicable within a reasonable timeframe. By utilizing a modern variant of evolutionary algorithms, the so-called evolution strategies with covariance matrix adaptation (CMA-ES), we demonstrated that there is a huge potential to save iterations compared to alternative, more common OAs. In this presentation, we discuss prominent characteristics of problems involving more than one realization of reality, focusing on the stacking approach, a common method to account for descriptive uncertainty. Here, during optimization, multiple realizations are considered simultaneously. A robust managerial solution has to succeed in all or at least most of the realizations. A practical consequence is that the number of realizations multiplies the computational time. Nevertheless, the results of our study are evidence for only a small fraction of the stack (the critical realizations) controlling the identification of the optimal solution. This observation encouraged us to develop a procedure which is based on dynamic stack ordering and to ignore uncritical solutions.