julilili42/papers huggingface dataset:
The role of the unaffected hemisphere in motor recovery after stroke
2010-01-20

Abstract The contribution of the ipsilateral (nonaffected) hemisphere to recovery of motor function after stroke is controversial. Under the assumption that functionally relevant areas within the ipsilateral motor system should be tightly coupled to the demand we used fMRI and acoustically paced movements of the right index finger at six different frequencies to define the role of these regions for recovery after stroke. Eight well‐recovered patients with a chronic striatocapsular infarction of the left hemisphere were compared with eight age‐matched participants. As expected the hemodynamic response increased linearly with the frequency of the finger movements at the level of the left supplementary motor cortex (SMA) and the left primary sensorimotor cortex (SMC) in both groups. In contrast, a linear increase of the hemodynamic response with higher tapping frequencies in the right premotor cortex (PMC) and the right SMC was only seen in the patient group. These results support the model of an enhanced bihemispheric recruitment of preexisting motor representations in patients after subcortical stroke. Since all patients had excellent motor recovery contralesional SMC activation appears to be efficient and resembles the widespread, bilateral activation observed in healthy participants performing complex movements, instead of reflecting maladaptive plasticity. Hum Brain Mapp, 2010. © 2010 Wiley‐Liss, Inc.
The Thioesterase Bhp is Involved in the Formation of β‐Hydroxytyrosine during Balhimycin Biosynthesis in Amycolatopsis balhimycina
2010-01-20

Abstract The putative hydrolase gene bhp from the balhimycin biosynthetic gene cluster has been cloned and overexpressed in Escherichia coli . The corresponding enzyme Bhp was purified to homogeneity by nickel‐chelating chromatography and characterized. Although Bhp has sequence similarities to hydrolases with “haloperoxidase”/perhydrolase activity, it did not show any enzymatic activity with standard “haloperoxidase”/perhydrolase substrates (e.g., monochlorodimedone and phenol red), nonspecific esterase substrates (such as p ‐nitrophenyl acetate, p ‐nitrophenyl phosphate and S ‐thiophenyl acetate) or the model lactonase substrate dihydrocoumarin. However, Bhp could be shown to catalyse the hydrolysis of S ‐β‐hydroxytyrosyl‐ N ‐acetyl cysteamine thioester (β‐OH‐Tyr‐SNAC) with 15 times the efficiency of S ‐ L ‐tyrosyl‐ N ‐acetyl cysteamine thioester ( L ‐Tyr‐SNAC). This is in agreement with the suggestion that Bhp is involved in balhimycin biosynthesis, during which it was supposed to catalyse the hydrolysis of β‐OH‐Tyr‐ S ‐PCP (PCP=peptidyl carrier protein) to free β‐hydroxytyrosine (β‐OH‐Tyr) and strongly suggests that Bhp is a thioesterase with high substrate specificity for PCP‐bound β‐OH‐Tyr and not a “haloperoxidase”/perhydrolase or nonspecific esterase.
Electric Field Stimulation of Bipolar Cells in a Degenerated Retina—A Theoretical Study
2010-01-20

Subretinal implants are the subject of clinical investigation for their ability to evoke useful visual sensations in blind individuals via electrical stimulation of the diseased retina. We investigated the spatial characteristic of the retinal polarization obtained by electric field stimulation through a subretinally located monopolar electrode array and bipolar electrode array. By combining electric potential simulation through a boundary element method with a segmented cell model, we computed the membrane voltage at the axon terminal of the bipolar cells as a function of the axon length (50-110 microm) and the electrode diameter. We found that short OFF bipolar cells are predominantly addressed by small bipolar electrodes (diameter between 60 and 100 microm) and by using a short duration ( < 150 micros) of the stimulating voltage pulse. Long ON cells are best addressed by large monopolar electrodes (diameter > 100 microm) and a long pulse duration ( > 150 micros). However, the low selectivity of the electric field stimulation with regard to the cell length does not enable the individual depolarization of long OFF cells and short ON cells. When the stimulation must take place at multiple retinal sites simultaneously, the bipolar electrode arrays allow for higher spatial modulation of the polarization of the axon terminal than the monopolar arrays.
Social Interaction Revealed by Motion: Dynamics of Neuromagnetic Gamma Activity
2010-01-21

Perception of dispositions of others revealed by movement is an essential ingredient of adaptive daily-life social behavior. Brain imaging points to several brain regions involved in visual processing of social interaction represented by motion of geometric shapes. However, temporal interrelations among these regions remain unknown. Keeping in mind that successful visual social perception depends on intact communication throughout the brain, we focus here on analysis of the induced gamma neuromagnetic response to social interaction revealed by motion. A peak of induced gamma activity of 62 Hz was found at 1 s from the stimulus onset over the right parieto-temporal junction. Two further enhancements in gamma response of lower frequency of 44 Hz occurred at 1.4 s over the medial prefrontal and posterior temporal cortices in the right hemisphere. Subsequent boosts of 44 Hz were found at 1.6 s over the left temporal and right posterior temporal cortices. For the first time, the findings identify the cortical network engaged in visual processing of social interaction revealed by motion and help to better understand proper functioning of the social brain circuitry.
Imaging Findings in Immunosuppressed Patients With Epstein Barr Virus–Related B Cell Malignant Lymphoma
2010-01-21

EBV-related malignant lymphoproliferative diseases share common features with other aggressive lymphomas, including a high degree of extranodal involvement, tumor vascularization, and tumor necrosis. Cognizance of the particular underlying diseases and conditions associated with the development of EBV-related lymphoproliferative diseases and associated imaging results should provide more accurate diagnosis.
Spectral evolution of bright NS LMXBs withINTEGRAL: an application of the thermal plus bulk Comptonization model
2010-01-21

Aims: The aim of this work is to investigate in a physical and quantitative way the spectral evolution of bright neutron star low-mass X-ray binaries (NS LMXBs) with special regard to the transient hard X-ray tails.&#13;\\nMethods: We analyzed INTEGRAL data for five sources (GX 5-1, GX 349+2, GX 13+1, GX 3+1, GX 9+1) and built broad-band X-ray spectra from JEM-X1 and IBIS/ISGRI data. For each source, X-ray spectra from different states were fitted with the recently proposed model compTB.&#13;\\nResults: The spectra have been fit with a two-compTB model. In all cases the first compTB describes the dominant part of the spectrum that we interpret as thermal Comptonization of soft seed photons (&lt;1 keV), likely from the accretion disk, by a 3-5 keV corona. In all cases, this component does not evolve much in terms of Comptonization efficiency, with the system converging to thermal equilibrium for an increasing accretion rate. The second compTB varies more dramatically, spanning from bulk plus thermal Comptonization of blackbody seed photons to the blackbody emission alone. These seed photons (R &lt; 12 km, kTs &gt; 1 keV), likely from the neutron star and the innermost part of the system, the transition layer, are Comptonized by matter in a converging flow. The presence and nature of this second compTB component (whether a pure blackbody or Comptonized) are related to the inner local accretion rate which can influence the transient behavior of the hard tail: high values of accretion rates correspond to an efficient bulk Comptonization process (bulk parameter δ≠0), while even higher values of accretion rates suppress the Comptonization, resulting in simple blackbody emission (δ=0).&#13;\\nConclusions: The spectral evolution of the sources has been successfully studied in terms of thermal and bulk Comptonization efficiency in relation to the physical conditions in the transition layer.
Investigation of the Crossreactivity of Mycophenolic Acid Glucuronide Metabolites and of Mycophenolate Mofetil in the Cedia MPA Assay
2010-01-22

The immunosuppressant mycophenolic acid (MPA) used for solid organ transplantation is predominantly metabolized to a pharmacologically inactive phenolic glucuronide (MPAG) and, to a lesser extent, to the pharmacologically active acyl glucuronide (AcMPAG). The recently introduced CEDIA Mycophenolic Acid Assay from Microgenics has been reported to overestimate MPA in clinical samples and crossreactivity with AcMPAG has been suspected. A detailed investigation of the crossreactivity of AcMPAG and the prodrug mycophenolate mofetil (MMF) in the CEDIA assay is presented using pure substances. In addition, MPA concentrations in plasma were compared with a validated high-performance liquid chromatography-ultraviolet method. Plasma samples from kidney (KTx, n = 50), heart (HTx, n = 50), and liver (LTx, n = 50) transplant recipients were analyzed by the CEDIA (MPA) and a high-performance liquid chromatography-ultraviolet method (MMF, MPA, MPAG, AcMPAG). Crossreactivity of MMF (0.93-46.3 mg/L), MPAG (50-1000 mg/L), and AcMPAG (0.5-10 mg/L) was investigated using spiked drug-free plasma. Method comparison was performed using Bland & Altman and Passing & Bablok analysis. The method bias was correlated to AcMPAG concentrations using Spearman's rank correlation. Crossreactivity with AcMPAG and MMF was concentration-dependent and reached 215% and 143%, respectively. There was no crossreactivity with MPAG. The CEDIA assay showed a mean positive bias of 36.3% in patient samples. The mean bias was lowest with HTx samples (15%), 41.7% with KTx samples, and highest with LTx samples (52.3%). There was a positive correlation between the method bias and AcMPAG concentrations (r = 0.829; P < 0.001). No MMF was detected in patient samples. The CEDIA overestimates MPA concentrations on average by 36%. This bias is mainly the result of AcMPAG as previously observed with the EMIT MPA assay. It should be considered that the putative therapeutic range for MPA with the CEDIA assay will be higher than the range using high-performance liquid chromatography.
Quantum-chemical simulation of solid-state NMR spectra: the example of a molecular tweezer host–guest complex
2010-01-22

Abstract\\n A systematic quantum-chemical study of the convergence of proton&#13;\\nNMR shieldings with the size of solid-state fragments is presented&#13;\\nfor a host-guest system.&#13;\\nThe largest system computed at Hartree-Fock and density-functional theory&#13;\\nlevels comprises a full first shell of complexes surrounding&#13;\\na central unit within an X-ray based structure and&#13;\\na total of 1196 atoms and 13260 basis functions.&#13;\\nWhile the influence of methodological aspects can be considered to be converged&#13;\\nwithin the error bars of experiment and theory, the deviation&#13;\\nof one of the protons provides evidence for the possibility&#13;\\nof a dynamic rotation process of the guest within the host complex.
Fluorescence intensity decay shape analysis microscopy (FIDSAM) for quantitative and sensitive live-cell imaging
2010-01-22

Fluorescence microscopy became an invaluable tool in cell biology in the past 20 years. However, the information that lies in these studies is often corrupted by a cellular fluorescence background known as autofluorescence. Since the unspecific background often overlaps with most commonly used labels in terms of fluorescence spectra and fluorescence lifetime, the use of spectral filters in the emission beampath or timegating in fluorescence lifetime imaging (FLIM) is often no appropriate means for distinction between signal and background. Despite the prevalence of fluorescence techniques only little progress has been reported in techniques that specifically suppress autofluorescence or that clearly discriminate autofluorescence from label fluorescence. Fluorescence intensity decay shape analysis microscopy (FIDSAM) is a novel technique which is based on the image acquisition protocol of FLIM. Whereas FLIM spatially resolved maps the average fluorescence lifetime distribution in a heterogeneous sample such as a cell, FIDSAM enhances the dynamic image contrast by determination of the autofluorescence contribution by comparing the fluorescence decay shape to a reference function. The technique therefore makes use of the key difference between label and autofluorescence, i.e. that for label fluorescence only one emitting species contributes to fluorescence intensity decay curves whereas many different species of minor intensity contribute to autofluorescence. That way, we were able to suppress autofluorescence contributions from chloroplasts in Arabidopsis stoma cells and from cell walls in Arabidopsis hypocotyl cells to background level. Furthermore, we could extend the method to more challenging labels such as the cyan fluorescent protein CFP in human fibroblasts.
The fluorescence lifetime of BRI1-GFP as probe for the noninvasive determination of the membrane potential in living cells
2010-01-22

As the excited state lifetime of a fluorescent molecule depends on its environment, it is possible to use it as a probe for physico-chemical parameters of the surrounding medium. Whereas this is well known for many solid guest/host systems, only few reports of quantitative, temporal resolved in vivo studies to monitor the nano-environment for a protein-coupled chromophore such as GFP are known from literature. Here we present a novel approach to determine the membrane potential of living (plant) cells based on the fluorescence lifetime (FLT) analysis of membrane-located GFP. By using confocal sample scanning microscopy (CSSM) combined with fluorescence lifetime imaging microscopy, we recently showed that the phytohormone brassinolide (BL) induces cell wall expansion and a decrease in the FLT of the BRI1-GFP in living cells of Arabidopsis thaliana seedlings. BRI1 is the dominant functional receptor for BL in Arabidopsis and locates to the plasma membrane. Although the dependence of the FLT of GFP on its physico-chemical environment such as pH-value, refractive index and pressure has been reported, the observed FLT decrease of BRI1-GFP in response to BL application could not be explained by these parameters. However, our in vivo FLT and CSSM analyses indicate that the BLinduced change in the FLT of BRI1-GFP is caused by hyperpolarisation of the plasma membrane (Em). Thus, our results indicate that BRI1-GFP serves as sensitive and non-invasive probe for recording the Em of the plasma membrane in living plant cells with high spatio-temporal resolution.
Topography mapping of whole body adipose tissue using A fully automated and standardized procedure
2010-01-23

Abstract Purpose: To obtain quantitative measures of human body fat compartments from whole body MR datasets for the risk estimation in subjects prone to metabolic diseases without the need of any user interaction or expert knowledge. Materials and Methods: Sets of axial T1‐weighted spin‐echo images of the whole body were acquired. The images were segmented using a modified fuzzy c‐means algorithm. A separation of the body into anatomic regions along the body axis was performed to define regions with visceral adipose tissue present, and to standardize the results. In abdominal image slices, the adipose tissue compartments were divided into subcutaneous and visceral compartments using an extended snake algorithm. The slice‐wise areas of different tissues were plotted along the slice position to obtain topographic fat tissue distributions. Results: Results from automatic segmentation were compared with manual segmentation. Relatively low mean deviations were obtained for the class of total tissue (4.48%) and visceral adipose tissue (3.26%). The deviation of total adipose tissue was slightly higher (8.71%). Conclusion: The proposed algorithm enables the reliable and completely automatic creation of adipose tissue distribution profiles of the whole body from multislice MR datasets, reducing whole examination and analysis time to less than half an hour. J. Magn. Reson. Imaging 2010; 31: 430–439. © 2010 Wiley‐Liss, Inc.
Bimodular auxin response controls organogenesis in Arabidopsis
2010-01-25

Like animals, the mature plant body develops via successive sets of instructions that determine cell fate, patterning, and organogenesis. In the coordination of various developmental programs, several plant hormones play decisive roles, among which auxin is the best-documented hormonal signal. Despite the broad range of processes influenced by auxin, how such a single signaling molecule can be translated into a multitude of distinct responses remains unclear. In Arabidopsis thaliana , lateral root development is a classic example of a developmental process that is controlled by auxin at multiple stages. Therefore, we used lateral root formation as a model system to gain insight into the multifunctionality of auxin. We were able to demonstrate the complementary and sequential action of two discrete auxin response modules, the previously described SOLITARY ROOT/INDOLE-3-ACETIC ACID (IAA)14-AUXIN REPONSE FACTOR (ARF)7-ARF19–dependent lateral root initiation module and the successive BODENLOS/IAA12-MONOPTEROS/ARF5–dependent module, both of which are required for proper organogenesis. The genetic framework in which two successive auxin response modules control early steps of a developmental process adds an extra dimension to the complexity of auxin’s action.
Early signaling through the Arabidopsis pattern recognition receptors FLS2 and EFR involves Ca2+-associated opening of plasma membrane anion channels
2010-01-25

The perception of microbes by plants involves highly conserved molecular signatures that are absent from the host and that are collectively referred to as microbe-associated molecular patterns (MAMPs). The Arabidopsis pattern recognition receptors FLAGELLIN-SENSING 2 (FLS2) and EF-Tu receptor (EFR) represent genetically well studied paradigms that mediate defense against bacterial pathogens. Stimulation of these receptors through their cognate ligands, bacterial flagellin or bacterial elongation factor Tu, leads to a defense response and ultimately to increased resistance. However, little is known about the early signaling pathway of these receptors. Here, we characterize this early response in situ, using an electrophysiological approach. In line with a release of negatively charged molecules, voltage recordings of microelectrode-impaled mesophyll cells and root hairs of Col-0 Arabidopsis plants revealed rapid, dose-dependent membrane potential depolarizations in response to either flg22 or elf18. Using ion-selective microelectrodes, pronounced anion currents were recorded upon application of flg22 and elf18, indicating that the signaling cascades initiated by each of the two receptors converge on the same plasma membrane ion channels. Combined calcium imaging and electrophysiological measurements revealed that the depolarization was superimposed by an increase in cytosolic calcium that was indispensable for depolarization. NADPH oxidase mutants were still depolarized upon elicitor stimulation, suggesting a reactive oxygen species-independent membrane potential response. Furthermore, electrical signaling in response to either flg22 or elf 18 critically depends on the activity of the FLS2-associated receptor-like kinase BAK1, suggesting that activation of FLS2 and EFR lead to BAK1-dependent, calcium-associated plasma membrane anion channel opening as an initial step in the pathogen defense pathway.
Quantifiers in "than"-clauses
2010-01-25

The paper reexamines the interpretations that quantifiers in "than"-clauses give rise to. It develops an analysis that combines an interval semantics for the "than"-clause with a standard semantics for the comparative operator. In order to mediate between the two, interpretive mechanisms like maximality and maximal informativity determine selection of a point from an interval. The interval semantics allows local interpretation of the quantifier. Selection predicts which interpretation this leads to. Cases in which the prediction appears not to be met are explained via recourse to independently attested external factors (e.g. the interpretive possibilities of indefinites). The goal of the paper is to achieve coverage of the relevant data while maintaining a simple semantics for the comparative. A secondary objective is to reexamine, restructure and extend the set of data considered in connection with the problem of quantifiers in "than"-clauses. doi:10.3765/sp.3.1 <a href="http://semantics-online.org/sp-bib/beck.bib">BibTeX info</a>
Involvement of CD91 and scavenger receptors in Hsp70‐facilitated activation of human antigen‐specific CD4+ memory T cells
2010-01-25

Abstract Hsp70 plays several roles in the adaptive immune response. Based on the ability to interact with diverse peptides, extracellular Hsp70:peptide complexes exert profound effects both in autoimmunity and in tumor rejection by evoking potent T cell responses to the chaperoned peptide. The interaction with receptors on APC represents the basis for the immunological functions of Hsp70 and a critical point where the immune response can be regulated. Various surface proteins ( e.g. CD91, scavenger receptors (SR)) have been implicated in binding of Hsp70. In this study, antigenic peptides from tetanus toxin and influenza hemagglutinin complexed to human stress‐inducible Hsp70 were found to enhance the proliferation and cytokine production of human antigen‐specific CD4 + T cells. This was demonstrated in proliferation experiments using human monocytes as APC. Proliferated antigen‐specific cells were detected combining HLA‐DRB1 * 0401 or HLA‐DRB1 * 1101 tetramer and CFSE staining. Treating monocytes with CD91 siRNA diminished these effects. Additional blocking of SR by the SR ligand fucoidan completely abolished enhanced proliferation and production of Th1 and Th2 cytokines. Taken together, our data indicate that in the human system, CD91 and members of the SR family efficiently direct Hsp70:peptide complexes into the MHC class II presentation pathway and thus enhance antigen‐specific CD4 + T cell responses.