julilili42/papers huggingface dataset:
Diffusion tensor imaging of the lower leg musculature during exercise
2007-03-08

Echoplanar diffusion tensor imaging of musculature was performed using an adapted sequence with stimulated echo preparation and eddy current compensation. Reliable diffusion tensor data were obtained in short measuring time of 2 minutes. Image distortion problems due to eddy currents arising from long lasting diffusion sensitizing gradients could be overcome by insertion of additional gradient pulses in the TM interval of the stimulated echo preparation. In addition, a T<sub>2</sub>-weighted multi-contrast spin-echo sequence with seven echoes was applied for assessment of changes in T2 during exercise. The diffusion tensor and T2 in the musculature of the lower leg was investigated in 4 healthy subjects and maps of the trace and the three eigenvalues of the diffusion tensor, fractional anisotropy maps, and angle maps were calculated from examinations before and after 90 seconds of exhausting tiptoe exercises. For both fractional anisotropy and muscle fibre orientation obvious differences for the miscellaneous muscle groups could be observed, whereas the eigenvalues of the diffusion tensor were found rather homogenous in the whole calf musculature. All eigenvalues of the diffusion tensor of loaded muscles were significantly increased by 7-17% immediately after the exercise. Maximum increase (14-17%) was found in the smallest eigenvalue in gastrocnemius lateralis and soleus muscle.
Optimization of a single-shot EPI sequence for diffusion imaging of the human spinal cord
2007-03-08

Diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) are established techniques of magnetic resonance widely used for the characterization of the cerebral tissue. Despite the successful application in the brain, diffusion-weighted single-shot echo-planar-imaging (EPI) of the spinal cord is hindered by the need for highly-resolved spatial encoding in an area of strong magnetic field inhomogeneities, and the shortness of transverse relaxation time. The major aim of this study was the optimization of a reliable single-shot EPI sequence for DTI of the spinal cord at 1.5T. Ten healthy volunteers participated in the study (mean age=28.4±3.1). A single-shot EPI sequence with double spinecho diffusion preparation and nominal in-plane resolution of 0.9x0.9mm<sup>2</sup> was optimized with regard to cerebrospinal fluid artifacts, and contrast-to-noise ratio between gray matter (GM) and white matter (WM). The effective sequence resolution was evaluated on a phantom. A cardiac-pulse gated sequence with optimal matrix size (read x phase=64x32) and b-value (700s/mm<sup>2</sup>) allowed for the acquisition of highly-resolved images of the spinal cord (effective in-plane resolution=1.1mm). Preliminary results on two healthy volunteers showed that the butterfly-shaped GM is clearly recognizable in the reconstructed fractional anisotropy (FA) maps. Measured WM FA values were 0.698±0.076 and 0.756±0.046. No significant differences were found in the mean diffusivity computed in the WM as compared to the GM areas. Optimized spinal cord diffusion imaging provided promising preliminary results on healthy volunteers. The application of the proposed protocol in the assessment of neurological disorders may allow for improved characterization of healthy and impaired WM and GM.
Trehalose turnover during abiotic stress in arbuscular mycorrhizal fungi
2007-03-12

Trehalose is a common reserve carbohydrate in fungi, whose role has been recently extended to other cellular functions, such as stress tolerance, glycolysis control, sporulation and infectivity of some pathogenic strains. To gain some insight into the role of trehalose during abiotic stress in arbuscular mycorrhizal (AM) fungi, we assessed trehalose content as well as transcriptional regulation and enzyme activity of neutral trehalase and trehalose-6-phosphate phosphatase in Glomus intraradices in response to heat shock, chemical or osmotic stress. Prolonged or intensive exposure to heat or chemical stress, but not osmotic stress, caused an increase of trehalose in the cell. We found this associated with transient up-regulation of the trehalose-6-P phosphatase (GiTPS2) transcript that coincided with moderate increases in enzyme activity. By contrast, there were no changes in neutral trehalase (GiNTH1) RNA accumulation in response to stress treatments, while they promoted, in most cases, an increase in activity. After stress had ceased, trehalose returned to basal concentrations, pointing to a role of neutral trehalase activity in heat shock recovery. A yeast complementation assay confirmed the role of neutral trehalase in thermotolerance. Taken together, these results indicate that trehalose could play a role in AM fungi during the recovery from certain stresses such as heat shock and chemical treatment.
Direct WIMP detection in directional experiments
2007-03-12

The recent WMAP data have confirmed that exotic dark matter together with the vacuum energy (cosmological constant) dominate in the flat Universe. Thus the direct dark matter search, consisting of detecting the recoiling nucleus, is central to particle physics and cosmology. Modern particle theories naturally provide viable cold dark matter candidates with masses in the GeV-TeV region. Supersymmetry provides the lightest supersymmetric particle (LSP), theories in extra dimensions the lightest Kaluza-Klein particle (LKP) etc. In such theories the expected rates are much lower than the present experimental goals. So one should exploit characteristic signatures of the reaction, such as the modulation effect and, in directional experiments, the correlation of the event rates with the sun's motion. In standard non directional experiments the modulation is small, less than two per cent and the location of the maximum depends on the unknown particle's mass. In directional experiments, in addition to the forward-backward asymmetry due to the sun's motion, one expects a larger modulation, which depends on the direction of observation. We study such effects both in the case of a light and a heavy target. Furthermore, since it now appears that the planned experiments will be partly directional, in the sense that they can only detect the line of the recoiling nucleus, but not the sense of direction on it, we study which of the above mentioned interesting features, if any, will persist in these less ambitious experiments.
Optical Fourier Transform Spectroscopy of Single‐Walled Carbon Nanotubes and Single Molecules
2007-03-12

Abstract We use two‐beam interferometry in combination with confocal microscopy for Raman and fluorescence studies of spatially isolated single‐walled carbon nanotubes and single dye molecules. We investigate the potential of optical Fourier transform spectroscopy for the spectral characterization of single molecules and molecular nanostructures. We demonstrate that it is possible to obtain the temporal coherence characteristics as well as reliable spectroscopic data of the single photon fluorescence emission of an isolated molecule from one measured interferogram, even though the molecule exhibits intensity fluctuations and spectral jumps.
Radicular and nonradicular back pain in Parkinson's disease: A controlled study
2007-03-13

Abstract Postural abnormalities and increased muscle tone in Parkinson's disease (PD) may cause back pain. In this controlled study, we analyzed features of back pain in PD patients. The prevalence of back pain was 74% in PD patients (n = 101) when compared with 27% in control patients (n = 132; P &lt; 0.0001, fisher's exact test), but did not correlate with disease severity or duration. The mean back pain intensity (visual analog scale of 0–10) was 4.3 for PD patients, and 1.3 for controls. Both radicular and nonradicular types of back pain were more frequent, and back pain caused more impairment in PD patients. However, it is noteworthy that the PD patients in our study did not receive more pain medication than control patients. This suggests that back pain in PD patients is often neglected and insufficiently treated. Our results argue for the routine evaluation of back pain in every patient suffering from PD. © 2007 Movement Disorder Society
Detection of extended very-high-energy γ-ray emission towards the young stellar cluster Westerlund 2
2007-03-13

Aims. Results from γ-ray observations by the HESS telescope array in the direction of the young stellar cluster Westerlund 2 are presented. Methods. Stereoscopic imaging of Cherenkov light emission of γ-ray induced showers in the atmosphere is used to study the celestial region around the massive Wolf-Rayet (WR) binary WR 20a. Spectral and positional analysis is performed using standard event reconstruction techniques and parameter cuts. Results. The detection of a new γ-ray source is reported from HESS observations in 2006. HESS J1023-575 is found to be coincident with the young stellar cluster Westerlund 2 in the well-known HII complex RCW 49. The source is detected with a statistical significance of more than 9σ, and shows extension beyond a point-like object within the HESS point-spread function. The differential γ-ray spectrum of the emission region is measured over approximately two orders of magnitude in flux. Conclusions.The spatial coincidence between HESS J1023-575 and the young open cluster Westerlund 2, hosting e.g. the massive WR binary WR 20a, requires one to look into a variety of potential models to account for the observed very-high-energy (VHE) γ-ray emission. Considered emission scenarios include emission from the colliding wind zone of WR 20a, collective stellar winds from the extraordinary ensemble of hot and massive stars in the stellar cluster Westerlund 2, diffusive shock acceleration in the wind-blown bubble itself, and supersonic winds breaking out into the interstellar medium (ISM). The observed source extension argues against a single star origin of the observed VHE emission.
Computer-based Studies of Diffusion through Stomata of Different Architecture
2007-03-13

Variation of stomatal structure may, with unchanged pore size and depth, profoundly affect gas exchange and the pathways of liquid water inside the leaf. Equations for calculation of stomatal conductance which are solely based on stomatal density and pore depth and size can significantly overestimate stomatal conductance.
Biosynthesis of Wdr16, a marker protein for kinocilia‐bearing cells, starts at the time of kinocilia formation in rat, andwdr16gene knockdown causes hydrocephalus in zebrafish1
2007-03-13

Abstract The rat ortholog of the WD40 repeat protein Wdr16 is abundantly expressed in testis and cultured ependymal cells. Low levels are found in lung and brain, respectively, while it is absent from kinocilia‐free tissues. In testis and ependymal primary cultures, Wdr16 messenger RNA appears concomitantly with the messages for sperm‐associated antigen 6, a kinocilia marker, and for hydin, a protein linked to ciliary function and hydrocephalus. In testis, ependyma and respiratory epithelium, the Wdr16 protein is up‐regulated together with kinocilia formation. The wdr16 gene is restricted to genera in possession of kinocilia, and it is strongly conserved during evolution. The human and zebrafish proteins are identical in 62% of their aligned amino acids. On the message level, the zebrafish Wdr16 ortholog was found exclusively in kinocilia‐bearing tissues by in situ hybridisation. Gene knockdown in zebrafish embryos by antisense morpholino injection resulted in severe hydrocephalus formation with unaltered ependymal morphology or ciliary beat. Wdr16 can be considered a differentiation marker of kinocilia‐bearing cells. In the brain, it appears to be functionally related to water homeostasis or osmoregulation.
70‐kDa heat shock proteins: Specific interactions with HLA‐DR molecules and their peptide fragments
2007-03-13

Abstract Heat shock protein 70 (HSP70):peptide complexes are involved in MHC class I and class II‐restricted antigen presentation enabling enhanced activation of antigen‐specific T cells. Here, we investigated the potential of bacterial and mammalian HSP70 molecules to interact with peptide fragments from HLA‐DR and the corresponding complete HLA‐DR molecules. Peptide fragments were found to interact with DnaK, the HSP70 homologue from E. coli , but less with stress‐inducible human Hsp70. Only a peptide sequence exclusively found in rheumatoid arthritis‐protective HLA‐DR molecules did not interact with DnaK. Subsequently, we investigated the interaction of complete HLA‐DR molecules with HSP70 and detected a specific HSP70:HLA‐DR interaction, with highest affinity for human stress‐inducible Hsp70. In contrast to the peptide fragments, no allele‐specific differences in Hsp70 affinity were detected with complete HLA‐DR molecules. Interaction with HLA‐DR molecules was increased at lowered pH values, whereas HSP70‐chaperoned peptides were released at acidic pH, thus HSP70 could serve as scanner and carrier for antigenic peptides of self or foreign origin and transfer chaperoned peptides onto MHC class II molecules in acidic late endosomal compartments. Our findings indicate that direct interaction between mammalian HSP70 and HLA‐DR molecules could be involved in the HSP70‐mediated enhancement of MHC class II‐restricted peptide presentation and CD4 + T cell activation.
Global molecular phylogeography reveals persistent Arctic circumpolar isolation in a marine planktonic protist
2007-03-14

The high-latitude planktonic foraminifera have proved to be particularly useful model organisms for the study of global patterns of vicariance and gene flow in the oceans. Such studies demonstrate that gene flow can occur over enormous distances in the pelagic marine environment leading to cosmopolitanism but also that there are ecological and geographical barriers to gene flow producing biogeographic structure. Here, we have undertaken a comprehensive global study of genetic diversity within a marine protist species, the high-latitude planktonic foraminiferan Neogloboquadrina pachyderma . We present extensive new data sets from the North Pacific and Arctic Oceans that, in combination with our earlier data from the North Atlantic and Southern Oceans, allow us to determine the global phylogeography of this species. The new genetic data reveal a pattern of Arctic circumpolar isolation and bipolar asymmetry between the Atlantic and Pacific Oceans. We show that the ancestry of North Pacific N. pachyderma is relatively recent. It lies within the upwelling systems and subpolar waters of the Southern Hemisphere and remarkably not within the neighboring Arctic Ocean. Instead, the Arctic Ocean population forms a genetic continuum with the North Atlantic population, which became isolated from the southern populations much earlier, after the onset of Northern hemisphere glaciation. Data from the planktonic foraminiferal morphospecies Globigerina bulloides is also introduced to highlight the isolation and endemism found within the subpolar North Pacific gyre. These data provide perspective for interpretation and discussion of global gene flow and speciation patterns in the plankton.
Cancer immunoediting by GITR (glucocorticoid‐induced TNF‐related protein) ligand in humans: NK cell/tumor cell interactions
2007-03-14

ABSTRACT Glucocorticoid‐induced TNF‐related protein (GITR) has been shown to stimulate T cell‐mediated antitumor immunity in mice. However, the functional relevance of GITR and its ligand (GITRL) for non‐T cells has yet to be fully explored. In addition, recent evidence suggests that GITR plays different roles in mice and humans. We studied the role of GITR‐GITRL interaction in human tumor immunology and report for the first time that primary gastrointestinal cancers and tumor cell lines of different histological origin express substantial levels of GITRL. Signaling through GITRL down‐regulated the expression of the immunostimulatory molecules CD40 and CD54 and the adhesion molecule EpCAM, and induced production of the immunosuppressive cytokine TGF‐β by tumor cells. On NK cells, GITR is constitutively expressed and up‐regulated following activation. Blocking GITR‐GITRL interaction in cocultures of tumor cells and NK cells substantially increased cytotoxicity and IFN‐γ production of NK cells demonstrating that constitutive expression of GITRL by tumor cells diminishes NK cell antitumor immunity. GITRL‐Ig fusion protein or cell surface‐expressed GITRL did not induce apoptosis in NK cells, but diminished nuclear localized c‐Rel and RelB, indicating that GITR might negatively modulate NK cell NF‐κB activity. Taken together, our data indicate that tumor‐expressed GITRL mediates immunosubversion in humans.—Baltz, K. M., Krusch, M., Bringmann, A., Brossart, P., Mayer, F., Kloss, M., Baessler, T., Kumbier, I., Peterfi, A., Kupka, S., Kroeber, S., Menzel, D., Radsak, M. P., Rammensee, H.‐G., Salih, H. R. Cancer immu‐noediting by GITR (glucocorticoid‐induced TNF‐related protein) ligand in humans: NK cell/tumor cell interactions. FASEB J. 21, 2442–2454 (2007)
Maillard reaction products enriched food extract reduce the expression of myofibroblast phenotype markers
2007-03-14

Abstract Advanced glycation end products (AGE) are associated with a wide range of degenerative diseases. The present investigation aimed at analysing the influence of AGE containing nutritional extracts on cardiac fibroblasts (CFs) as the major cell type responsible for cardiac fibrosis. Mice CFs were treated with bread crust extract (BCE) which contained significant amounts of a variety of AGE modifications. BCE treatment with up to 30 mg/mL did not impair cell viability. Furthermore, BCE induced a moderate elevation of reactive oxygen species (ROS) production and activation of redox sensitive pathways like the p42/44 MAPK , p38 MAPK and NF‐κB but did not alter Akt kinase phosphorylation. Expression of smooth muscle α‐actin and tropomyosin‐1, which represent markers for myofibroblast differentiation, was reduced after bread crust treatment. These data suggest a putative antifibrotic effect of melanoidin‐rich food.
Effect of fluorination on the electronic structure and optical excitations of π-conjugated molecules
2007-03-15

Fluorination of π-conjugated organic molecules is a strategy to obtain possible n-type conducting and air-stable materials due to the lowering of the frontier molecular orbitals (MOs) by the high electronegativity of fluorine. Nevertheless, the resulting optical gaps may be widened or narrowed, depending on the molecular backbone and/or the number and position of the fluorine atoms. The authors have performed time-dependent density functional theory calculations to address the subtle influence of fluorine substitution on the absolute MO energies and the subsequent impact on the optical transitions in homologous conjugated oligomers based on thiophene and acene units.
Efficient Mapping and Functional Verification of Parallel Algorithms on a MultiüContext Reconfigurable Architecture
2007-03-15

Parallel multiucontext reconfigurable architectures provide very attractive platforms with respect to computational performance and reconfigurable features. Today?s challenge is the exploitation of this reconfigurable and computational potential to ascertain efficient solution for mapping applications onto these architectures. The demand for appropriate tools is evident. In this paper we provide a combination and a mutual adaption of two separate tools to create a continuous design flow for parallel multiucontext reconfigurable architectures. Especially we present the interaction of a parameterized mapping tool for mapping compute intensive algorithms on processor arrays and a subsequent verification of the mapping results using the Configurable Reconfigurable Core (CRC) architecture model. The SystemC implementation of the CRC model leads to a cycle accurate functional simulation of the realization. Using this continuous design flow we derive an efficient realization of the edge detection algorithm (EDA) on a parallel multiucontext reconfigurable architecture. We describe in detail how the parallel realization of the EDA has to be translated in a specification for programming the CRC model.
Methanesulfonic Acid
2007-03-15

[75-75-2] CH4O3S (MW 96.12) InChI = 1S/CH4O3S/c1-5(2,3)4/h1H3,(H,2,3,4) InChIKey = AFVFQIVMOAPDHO-UHFFFAOYSA-N (cyclocondensation reagent; precursor for methanesulfonyl chloride and anhydride; catalyst for polymerization, alkylation, and esterification reactions) Alternate Name: MsOH. Physical Data: mp 20 °C; bp 167 °C/10 mmHg, 122 °C/1 mmHg; d 1.481 g cm−3; nD20 1.3210. Solubility: sol water, ethanol, ether; insol hexane; very sparingly sol benzene, toluene. Form Supplied in: technical quality is 95% pure containing 2% water. Analysis of Reagent Purity: 17O NMR.1 Preparative Method: by oxidation of Dimethyl Sulfide with Dimethyl Sulfoxide in the presence of water and a catalytic amount of Hydrogen Bromide.17 Purification: stir with P2O5 (20 g for 500 mL of the acid) at 100 °C for 0.5 h and then distill under vacuum. Handling, Storage, and Precautions: irritant and highly corrosive liquid; should be stored in glass containers. Use in a fume hood.
Propylene Oxide
2007-03-15

[75-56-9] C3H6O (MW 58.09) InChI = 1S/C3H6O/c1-3-2-4-3/h3H,2H2,1H3 InChIKey = GOOHAUXETOMSMM-UHFFFAOYSA-N (monomer for polymerization; electrophile; chiral building block) Alternate Names: 1,2-epoxypropane; methyloxirane. Physical Data: mp −112 °C; bp 34 °C; d 0.859 g cm−3; [α]D20 +14.6° for the (R)-enantiomer, corrected to 100% ee. Solubility: sol H2O (405 g L−1); miscible with organic solvents. Form Supplied in: colorless liquid; commercially available as a racemic mixture and as the enantiomers. Drying: distillation from calcium hydride or calcium. Upon cooling, a hydrate C3H6O·(H2O)16 of mp −3 °C is precipitated from the moist oxirane as white crystals.2 Analysis of Reagent Purity: 13C NMR (CDCl3): δ 47.1, 46.8 (C-1, C-2), 17.2 (C-3) ppm; determination of ee by complexation gas chromatography on nickel(II) bis[3-heptafluorobutanoyl-(1R)-camphorate] in squalane, separation factor α 1.24 at 50 °C;3 other suitable chiral stationary phases are nickel(II) bis[2-heptafluorobutanoyl-(S)-4-methylthujan-3-onate] and manganese(II) bis[3-heptafluorobutanoyl-(1R)-camphorate].4 Preparative Methods: (R)-propylene oxide is prepared (eq 1) in three steps: diazotization of (S)-alanine with Sodium Nitrite in hydrochloric acid; to give (S)-2-chloropropanoic acid; reduction to 2-chloropropan-1-ol with Lithium Aluminum Hydride; and cyclization by distillation from Potassium Hydroxide pellets.4, 5 (1) The (S)-enantiomer is prepared from (S)‐Ethyl Lactate via (S)-propane-1,2-diol, and cyclization of a mixture of (S)-2-acetoxy-1-bromopropane and (R)-2-bromo-1-acetoxypropane (eq 2).6, 7 (2) Alternatively, conversion of (S)-ethyl lactate into the mesylate is followed by reduction of the ester group with Aluminum Hydride/THF and ring closure with aqueous KOH.8 Another route to (S)-propylene oxide involves protection of the (secondary) hydroxyl group of (S)-ethyl lactate with Ethyl Vinyl Ether, followed by reduction of the ester group with LiAlH4, conversion of the primary hydroxyl group into the tosylate, acidic deprotection of the secondary hydroxyl group, and cyclization with aqueous KOH.9 By means of a combined microbial/chemical synthesis, (R)-propylene oxide is obtained from glucose with ee >99%.10 Metal-mediated access to both enantiomers is provided by either chromatographic or kinetic resolution of racemic propylene oxide, and also by asymmetric epoxidation of propylene.11 Handling, Storage, and Precautions: a suspected carcinogen for humans; it is inflammable and explosive; because of its high volatility, cooling to 0 °C before use is recommended. Use in a fume hood.