bluuebunny/crossref_metadata_2025_split huggingface dataset:
Assessment of solvent residues accessibility using three Sulfo‐NHS‐biotin reagents in parallel: application to footprint changes of a methyltransferase upon binding its substrate
Authors: Gabant Guillaume , Augier Julie , Armengaud Jean 
Published: October 2007

AbstractNHS‐biotin modification as a specific lysine probe coupled to mass spectrometry detection is increasingly used over the past years for assessing amino acid accessibility of proteins or complexes as an alternative when well‐established methods are challenged. We present a strategy based on usage in parallel of three commercially available reagents (Sulfo‐NHS‐biotin, Sulfo‐NHS‐LC‐biotin, and Sulfo‐NHS‐LC‐LC‐biotin) to efficiently assess the solvent accessibility of amino acids using MALDI‐TOF mass spectrometry. The same qualitative pattern of reactivity was observed for these three reagents on the THUMPα protein at four reagent/polypeptide molar ratios (2 : 1, 6 : 1, 13 : 1, and 26 : 1). Peptide assignment of the detected ions gains in accuracy because of the triple redundancy due to specific increments of monoisotopic mass. These reagents are a good alternative to isotope labeling when using only a single MALDI‐TOF mass spectrometer. We observed that hydroxyl groups of serine and tyrosine residues were also modified by these Sulfo‐NHS‐biotin reagents. The low amount of protein required and the method's simplicity make this procedure accessible and affordable in order to obtain topological information on proteins difficult to purify. This method was used to identify two lysine residues of the TrmG10 methyltransferase from Pyrococcus abyssi that were differentially reactive, modified in the protein but not in the tRNA–protein complex. Copyright © 2007 John Wiley & Sons, Ltd.
Astrocytes stimulate interleukin‐17 and interferon‐γ production in vitro
Authors: Miljkovic Djordje , Momcilovic Miljana , Stojanovic Ivana , Stosic‐Grujicic Stanislava , Ramic Zorica , Mostarica‐Stojkovic Marija 
Published: October 2007

AbstractAstrocytes play important roles in the complex and as yet not very well understood net of interactions among resident and infiltrating cells during central nervous system (CNS) inflammation. In such an intricate network, cytokines represent an essential means for intercellular communication, and astrocytes are able to affect their generation and/or release. Among various cytokines produced by infiltrating cells, interferon (IFN)‐γ and interleukin (IL)‐17 are the focus of this research, because they are pivotal cytokines of helper T‐cell type 1 (Th1) and helper T‐cell type 17 (Th17), respectively. Importantly, both Th1 and Th17 cells, as well as their cytokines, have been shown to be of importance for the pathogenesis of experimental autoimmune encephalomyelitis (EAE), an animal model of a prototypical CNS disease with inflammatory pathogenesis, multiple sclerosis. Therefore, the influence of astrocytes on the generation of IFN‐γ and IL‐17 in concanavalin A‐ and myelin basic protein‐stimulated lymph node cells of healthy rats and rats with developing EAE, respectively, was investigated in vitro. Astrocytes up‐regulated IL‐17 and IFN‐γ gene expression and protein synthesis in T cells, which coincided with astrocytes' ability to express IL‐23 subunit p19 and common IL‐12/IL‐23 subunit p40 but not IL‐12 subunit p35 in the cocultivations. These results suggest one more way in which astrocytes could contribute to the complex interactions during CNS inflammation. © 2007 Wiley‐Liss, Inc.
Lubrication performance of multialkylatedcyclopentane oils for sliding friction of steel under vacuum condition
Authors: Masuko Masabumi , Mizuno Hideaki , Suzuki Akihito , Obara Shingo , Sasaki Akira 
Published: October 2007

AbstractSliding friction experiments under vacuum lubricated with additive‐free multialkylatedcyclopentane (MAC) were carried out using a ball‐on‐disc tribometer with 440C stainless steel as the material of the specimen. Antiwear characteristics of additive‐free MAC during the steady friction region under vacuum were shown to be better than those of perfluoropolyether (PFPE). However, it was found that the friction coefficient lubricated with the additive‐free MAC under vacuum showed an initial seizure‐like high friction of approximately 0.2 at the beginning of the test, followed by a steady low friction of approximately 0.1. It was also found in contrast that PFPE did not show the initial seizure‐like high friction but maintained a lower friction coefficient than 0.1 throughout the experiment. The initial high wear volume lubricated with the additive‐free MAC was found to be related to the initial seizure‐like high friction. The tricresylphosphate formulation prevented the initial seizure‐like high friction. Copyright © 2007 John Wiley & Sons, Ltd.
Novel Amphiphilic Styrene‐Based Block Copolymers for Induced Surface Reconstruction
Authors: Funk Lutz , Brehmer Martin , Zentel Rudolf , Kang Huiman , Char Kookheon 
Published: October 2007

AbstractThis paper describes the synthesis of amphiphilic block copolymers by living radical polymerization (NMP) of new styrene‐like monomers. The polar monomers (ethylene oxide side chains and free hydroxyl‐ or amino‐groups after deprotection) were polymerized in a “protected form” to adjust the solubility of the monomers. In this way high molar mass polymers with a narrow polydispersity (around or below 1.2) were accessible. In the bulk state hydrophobic and hydrophilic domains demix. By exposing thin films of these polymers to vacuum (air) or alternatively to water or a hydrophilic surface it becomes possible to switch the surface polarity reversibly between contact angles of about 105° and 83° as a result of surface reconstruction. Through side chains of different length and with different functionalities, it was possible to adjust the glass transition temperatures to values between −2 °C to 140 °C for the hydrophilic blocks and −30 °C to 100 °C for the hydrophobic block. The wide range of the glass temperatures allowed it to find a block copolymer system with a slow kinetic concerning the surface reconstruction process, so that a mechanistic examination of the process by AFM was possible. It got, thereby, possible to detect the break‐up of the hydrophobic surface lamella and the upfold of the hydrophilic lamella in contact with water.magnified image
Flexural Creep Behavior of Unidirectional and Cross‐Ply All‐Poly(propylene) (PURE®) Composites
Authors: Banik Kaushik , Abraham Thomas N. , Karger‐Kocsis József 
Published: October 2007

AbstractThe long‐term viscoelastic behavior of reinforced all‐poly(propylene) composites was studied by flexural creep tests. Both unidirectional and cross‐ply laminates were prepared from PURE® coextruded tapes by vacuum bag molding in an autoclave. The specimens were subjected to isothermal creep tests at different temperatures ranging from 20 to 80 °C under an applied load. The time‐temperature superposition principle was verified for the creep data. An Arrhenius type relationship was found to better describe the shift data obtained from the creep tests. The activation energies relating to the different reinforcement architecture and different relaxation process were calculated.magnified image
SSFP and GRE phase contrast imaging using a three‐echo readout
Authors: Nielsen Jon‐Fredrik , Nayak Krishna S. 
Published: October 2007

AbstractA technique for rapid in‐plane phase‐contrast imaging with high signal‐to‐noise ratio (SNR) is described. Velocity‐encoding is achieved by oscillating the readout gradient, such that each 2DFT phase‐encode is acquired three times following a single RF slice‐selective excitation. Three images are reconstructed, from which both flow velocity and local resonance offset are calculated. This technique is compatible with both gradient‐recalled echo (GRE) and balanced steady‐state free precession (SSFP) imaging using a single steady‐state. The proposed technique enables 1D velocity mapping with 40% higher temporal resolution and 80% higher SNR, compared to conventional PC‐MRI using bipolar velocity‐encoding gradient pulses. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Temporal ΔB0 and relaxation in the rat heart
Authors: Dortch Richard D. , Does Mark D. 
Published: October 2007

AbstractField maps of the induced main magnetic field offset (ΔB0) were measured in the rat heart at various points in the cardiac cycle for the purpose of identifying their effects on relaxation measurements. The mean ΔB0 of the left ventricle averaged across rats was found to be 0.11 ± 0.35 ppm and 0.19 ± 0.39 ppm at the onset of systole and diastole, respectively. The root mean square (RMS) variation in resonant frequency of the left ventricle averaged across rats was found to be 0.09 ± 0.05 ppm and 0.06 ± 0.04 ppm during systole and diastole, respectively. Temporal variations in ΔB0 could substantially affect quantitative MRI measurements. To assess this, transverse relaxation rates (R2 and R) were measured at different points in the cardiac cycle, and the effects of ΔB0 were estimated using measured field map data. For a given region of the left ventricle, ΔB0 induced a mean error across rats of ≤3.9% for R2 and ≤9.6% for R. For R measurements, the static component of the field inhomogeneity was found to be responsible for most of the error induced. Magn Reson Med 58:939–946, 2007. © 2007 Wiley‐Liss, Inc.
Accelerated 3D echo‐planar spectroscopic imaging at 4 Tesla using modified blipped phase‐encoding
Authors: Ebel Andreas , Schuff Norbert 
Published: October 2007

AbstractWhole‐brain echo‐planar spectroscopic imaging (EPSI) often substantially lengthens MRI/MRSI (magnetic resonance spectroscopic imaging) protocols. To halve acquisition time, application of a blipped phase‐encoding (PE) gradient during the EPSI readout (RO) was previously suggested by PE of the even RO echoes in k‐space at an interstitial location along kPE, separated from the odd RO echoes, effectively reducing the number of PEs by a factor of 2. However, the approach is very susceptible to phase inconsistencies between even and odd RO echoes in the presence of B0 inhomogeneities and gradient imbalance, leading to ghosting in the PE direction. In this work, the blipped PE gradient is placed in between pairs of even/odd RO gradient lobes to avoid these problems. This approach is demonstrated in a phantom and in normal human brain in vivo at 4T. While the proposed method allows substantial reduction in metabolite ghosting, it may be limited by the presence of a relatively large spurious signal at the Nyquist frequency. Magn Reson Med 58:1061–1066, 2007. © 2007 Wiley‐Liss, Inc.
Viral capsids as MRI contrast agents
Authors: Liepold Lars , Anderson Stasia , Willits Deborah , Oltrogge Luke , Frank Joseph A. , Douglas Trevor , Young Mark 
Published: October 2007

AbstractViral capsids have the potential for combined cell/tissue targeting, drug delivery, and imaging. Described here is the development of a viral capsid as an efficient and potentially relevant MRI contrast agent. Two approaches are outlined to fuse high affinity Gd3+ chelating moieties to the surface of the cowpea chlorotic mottle virus (CCMV) capsid. In the first approach, a metal binding peptide has been genetically engineered into the subunit of CCMV. In a second approach gadolinium‐tetraazacyclododecane tetraacetic acid (GdDOTA) was attached to CCMV by reactions with endogenous lysine residues on the surface of the viral capsid. T1 and T2 ionic relaxivity rates for the genetic fusion particle were R1 = 210 and R2 = 402 mM−1s−1 (R2 at 56 MHz) and for CCMV functionalized with GdDOTA were R1 = 46 and R2 = 142 mM−1s−1 at 61 MHz. The relaxivities per intact capsid for the genetic fusion were R1 = 36,120 and R2 = 69,144 mM−1s−1 (R2 at 56 MHz) and for the GdDOTA CCMV construct were R1 = 2,806 and R2 = 8,662 mM−1s−1 at 61 MHz. The combination of high relaxivity, stable Gd3+ binding, and large Gd3+ payloads indicates the potential of viral capsids as high‐performance contrast agents. Magn Reson Med 58:871–879, 2007. © 2007 Wiley‐Liss, Inc.
Parallel imaging reconstruction for arbitrary trajectories using k‐space sparse matrices (kSPA)
Authors: Liu Chunlei , Bammer Roland , Moseley Michael E. 
Published: October 2007

AbstractAlthough the concept of receiving MR signal using multiple coils simultaneously has been known for over two decades, the technique has only recently become clinically available as a result of the development of several effective parallel imaging reconstruction algorithms. Despite the success of these algorithms, it remains a challenge in many applications to rapidly and reliably reconstruct an image from partially‐acquired general non‐Cartesian k‐space data. Such applications include, for example, three‐dimensional (3D) imaging, functional MRI (fMRI), perfusion‐weighted imaging, and diffusion tensor imaging (DTI), in which a large number of images have to be reconstructed. In this work, a systematic k‐space–based reconstruction algorithm based on k‐space sparse matrices (kSPA) is introduced. This algorithm formulates the image reconstruction problem as a system of sparse linear equations in k‐space. The inversion of this system of equations is achieved by computing a sparse approximate inverse matrix. The algorithm is demonstrated using both simulated and in vivo data, and the resulting image quality is comparable to that of the iterative sensitivity encoding (SENSE) algorithm. The kSPA algorithm is noniterative and the computed sparse approximate inverse can be applied repetitively to reconstruct all subsequent images. This algorithm, therefore, is particularly suitable for the aforementioned applications. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
In vivo MR spectroscopic imaging of polyunsaturated fatty acids (PUFA) in healthy and cancerous breast tissues by selective multiple‐quantum coherence transfer (Sel‐MQC): A preliminary study
Authors: He Qiuhong , Shkarin Pavel , Hooley Regina J. , Lannin Donald R. , Weinreb Jeffrey C. , Bossuyt Veerle Ilse Julie 
Published: October 2007

AbstractThe spatial distribution of polyunsaturated fatty acids (PUFA) in healthy and cancerous human breast tissues was measured in vivo with a selective multiple‐quantum coherence transfer (Sel‐MQC) technique. This method selectively detected the olefinic methylene protons (‐CH = CH‐) of PUFA at 5.3 ppm that were coupled with allylic methylene protons (‐CH2‐CH2‐CH=) of unsaturated acyl chain at 2.8 ppm. Unwanted lipid coherences and tissue water signal were dephased in a single scan. Breast PUFA were mapped at 1 cm3 voxel resolution in sagittal slices of nine breasts in six healthy female volunteers that were compared to invasive ductal carcinoma (IDC) in one breast cancer patient. The healthy breast tissue displayed continuous PUFA distribution. In some individuals, PUFA appeared throughout the breast tissue; in others they were only located in the central breast area. Decreased PUFA levels were detected in the IDC of the breast cancer patient. The magnetic resonance spectroscopic imaging (MRSI) measurement was consistent with the histological findings, ultrasound, and mammography images. PUFA patterns are sensitive to abnormal breast tissue changes including malignant transformations, and thus may serve as a biomarker for early diagnosis and therapeutic monitoring of breast disease. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
4D radial contrast‐enhanced MR angiography with sliding subtraction
Authors: Cashen Ty A. , Jeong Hyun , Shah Maulin K. , Bhatt Hem M. , Shin Wanyong , Carr James C. , Walker Matthew T. , Batjer H. Hunt , Carroll Timothy J. 
Published: October 2007

AbstractA method is presented for high spatial and temporal resolution 3D contrast‐enhanced magnetic resonance angiography. The overall technique involves a set of interrelated components suited to high‐frame‐rate angiography, including 3D cylindrical k‐space sampling, angular undersampling, asymmetric sampling, sliding window reconstruction, pseudorandom view ordering, and a sliding subtraction mask. Computer simulations and volunteer studies demonstrated the utility of each component of the technique. Angiograms of one hemisphere of the intracranial vasculature were acquired with a pixel size of 1.1 × 1.1 × 2.8 mm and a frame rate of 0.35 sec based on a temporal resolution of 3.5 sec. Such a 3D time‐resolved, or “4D,” technique has the potential to noninvasively acquire diagnostic quality images of certain anatomic regions with a frame rate fast enough to not only ensure the capture of an uncontaminated arterial phase, but even demonstrate contrast bolus flow dynamics. Clinical applications include noninvasive imaging of arteriovenous shunting, which is demonstrated with a patient study. Magn Reson Med 58:962–972, 2007. © 2007 Wiley‐Liss, Inc.
Apparent transverse relaxation rate in human brain varies linearly with tissue iron concentration at 4.7 T
Authors: Mitsumori Fumiyuki , Watanabe Hidehiro , Takaya Nobuhiro , Garwood Michael 
Published: October 2007

AbstractMultiple pairs of adiabatic passage pulses were implemented in a spin‐echo sequence to achieve accurate measurements of the apparent transverse relaxation time (T) in a short scan time. In experiments on agarose gel phantoms with T2 values ranging from 30 to 105 ms, the measured T values were in good agreement with transverse relaxation times measured with a nonselective Carr‐Purcell‐Meiboom‐Gill sequence. In experiments on normal human brain at 4.7 T, T values in five different gray matter regions were found to range from 38 ± 2 ms (globus pallidus) to 64 ± 2 ms (frontal cortex). The apparent relaxation rate (1/T) in these five regions showed strong correlation (r = 0.97) with published levels of iron (Fe) in those regions. The linear coefficient relating 1/T and [Fe] at 4.7 T was measured to be 0.551 (s · mg Fe/100 g f.w.)−1. When compared with the values obtained in a previous report for six different static fields (B0) up to 1.5 T, the current measurement confirms the linear dependence of the linear coefficient on B0 up to 4.7 T (r = 0.99). These results suggest that the T value in the human brain is predominantly affected by the nonhemin iron distribution. The strong correlation between the obtained T values and the regional iron concentrations suggests a role for this pulse sequence in quantifying in vivo brain iron at high magnetic field. Magn Reson Med 58:1054–1060, 2007. © 2007 Wiley‐Liss, Inc.
Spatial effects in the detection of γ‐aminobutyric acid: Improved sensitivity at high fields using inner volume saturation
Authors: Edden Richard A.E. , Barker Peter B. 
Published: October 2007

AbstractThe MEGA‐PRESS‐IVS method has been developed, which combines MEGA (a frequency‐selective editing technique) editing with the point‐resolved spectroscopy sequence (PRESS) and inner volume saturation (IVS) localization, reducing the deleterious effects of spatial variation in coupling evolution. The IVS method has been previously described for improved efficiency of lactate detection. The current study demonstrates that the combination of MEGA‐PRESS with IVS results in increased sensitivity for edited single‐voxel measurements of glutamate and γ‐aminobutyric acid (GABA). A four‐compartment model of coupling evolution is investigated through simple product operators and full spin‐system simulations and the predicted pattern of signal evolution is demonstrated through MEGA‐PRESS‐MRSI. MEGA‐PRESS‐IVS is then compared to MEGA‐PRESS in a phantom and an average signal increase of 24% is demonstrated in five healthy volunteers. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
q‐space diffusion of myelin‐deficient spinal cords
Authors: Biton I.E. , Duncan I.D. , Cohen Y. 
Published: October 2007

AbstractThe apparent water diffusion anisotropy in white matter (WM) of excised spinal cords of myelin‐deficient (md) rats and their age‐matched controls was studied by high‐b‐value q‐space diffusion MRS and MRI at different diffusion times. Non‐monoexponential signal decay was observed at long diffusion times. The mean displacements in the md spinal cords were found to be higher than those of the controls. The apparent anisotropy (AA) of the fast‐diffusing component was found to decrease more dramatically with the increase in diffusion time for the md spinal cords as compared with controls, whereas the AA of the slow‐diffusing component in the controls was found to increase with the increase in diffusion time while that of the md cords decreased with the increase in diffusion time. When diffusion MRI was performed, similar diffusion anisotropy was extracted for the md and control spinal cords at diffusion times of 22 and 50 ms. Only at a diffusion time of about 200 ms was a significant difference obtained in the AA of the two groups. This originates from the much smaller increase in the mean displacement perpendicular to the fiber direction in the control group vs. the md group when the diffusion time was increased. Magn Reson Med 58:993–1000, 2007. © 2007 Wiley‐Liss, Inc.
Ultrashort echo time spectroscopic imaging (UTESI) of cortical bone
Authors: Du Jiang , Hamilton Gavin , Takahashi Atsushi , Bydder Mark , Chung Christine B. 
Published: October 2007

AbstractCortical bone in the mature skeleton has a short T2* and produces no detectable signal with conventional MR sequences. A two‐dimensional ultrashort echo time (UTE) sequence employing half radio frequency (RF) pulse excitations and radial ramp sampling reduces the effective TE to 8 μs and is capable of detecting signals from cortical bone. We propose a time‐efficient UTE spectroscopic imaging (UTESI) technique based on an interleaved variable TE acquisition, preceded by long T2* signal suppression using either a 90° pulse and gradient dephasing or an inversion pulse and nulling. The projections were divided into multiple groups with the data for each group being collected with progressively increasing TE and interleaved projection angles. The undersampled projections within each group sparsely covered k‐space. A view sharing and sliding window reconstruction algorithm was implemented to reconstruct images at each TE, followed by Fourier transformation in the time domain to generate spectroscopic images. T2* was quantified through either exponential fitting of the time domain images or line fitting of the magnitude spectrum. Relative water content and the resonance frequency shift due to bulk susceptibility were also evaluated. The feasibility of this technique was demonstrated with phantom and volunteer studies on a clinical 3T scanner. Magn Reson Med 58:1001–1009, 2007. © 2007 Wiley‐Liss, Inc.
Sodium renal imaging in mice at high magnetic fields
Authors: Neuberger Thomas , Gulani Vikas , Webb Andrew 
Published: October 2007

AbstractThis work presents the first sodium MRI functional renal study on a mouse model. The tissue sodium concentration was monitored during induced diuresis with furosemide. By using density‐weighted chemical shift imaging (DWCSI) at high field strength a temporal resolution of less than 5 min for three dimensional (3D) data sets with high spatial resolution was achieved. A maximum increase of 20% in the cortex and a decrease of 45% of the original signal strength in the medulla were observed. These findings correspond well with experiments conducted on much larger rodent models. Magn Reson Med 58:1067–1071, 2007. © 2007 Wiley‐Liss, Inc.