bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on alkaloids binding to GC‐rich human survivin promoter DNA using positive and negative ion electrospray ionization mass spectrometry
Authors: Wang Zhaofu , Guo Xinhua , Liu Zhiqiang , Cui Meng , Song Fengrui , Liu Shuying 
Published: October 2007

AbstractElectrospray ionization mass spectrometry (ESI‐MS) was used to investigate the binding of 13 alkaloids to two GC‐rich DNA duplexes which are critical sequences in human survivin promoter. Negative ion ESI‐MS was first applied to screen the binding of the alkaloids to the duplexes. Six alkaloids (including berberine, jatrorrhizine, palmatine, reserpine, berbamine, and tetrandrine) show complexation with the target DNA sequences. Relative binding affinities were estimated from the negative ion ESI data, and the alkaloids show a binding preference to the duplex with higher GC content. Positive ion ESI mass spectra of the complexes were also recorded and compared with those obtained in negative ion mode. Only the 1 : 1 complex with berbamine was observed with lower abundance in the positive ion mass spectrum while complexes with the other alkaloids were absolutely absent. Collision‐induced dissociation (CID) experiments indicate that the complexes with the protoberberine alkaloids (berberine, jatrorrhizine, and palmatine) dissociate via base loss and covalent cleavage. In contrast, product ion spectra of the complexes with the alkaloids reserpine, berbamine, and tetrandrine show the predominant loss of a neutral alkaloid molecule, accompanied by base loss and covalent cleavage to a lesser extent. A comparison of the gas‐phase behaviors of complexes with the alkaloids to those with the traditional DNA binders has suggested an intercalative binding mode of these alkaloids to the target DNA duplexes. Copyright © 2007 John Wiley & Sons, Ltd.
Deletion of the STOP gene, a microtubule stabilizing factor, leads only to discrete cerebral metabolic changes in mice
Authors: Hanaya Ryosuke , Koning Estelle , Ferrandon Arielle , Schweitzer Annie , Andrieux Annie , Nehlig Astrid 
Published: October 2007

AbstractIn mice, deletion of the STOP protein leads to subtle anatomic changes and induces depleted synaptic vesicle pools, impaired synaptic plasticity, hyperdopaminergy, and major behavioral disorders alleviated by neuroleptics, hence leading to a schizophrenic‐like phenotype. In this study, we applied the quantitative autoradiographic [14C]2‐deoxyglucose technique to study to what extent the basal rate of cerebral glucose utilization in STOP‐knockout (STOP‐KO) mice occurs in regions where metabolic changes have been reported in schizophrenic patients. Studies were performed on wild‐type, heterozygous, and homozygous STOP‐KO mice (7–8 per group). Mice were implanted with femoral artery and vein catheters, and cerebral glucose utilization was quantified over 45 min. Compared with that in wild‐type mice, glucose utilization in STOP‐KO mice was significantly increased in the olfactory cortex, ventromedial and anterolateral hypothalamus, ventral tegmental area, and substantia nigra pars compacta. Nonsignificant increases, ranging between 9% and 19%, were recorded in the whole auditory system, CA1 pyramidal cell layer, and dorsal raphe. Glucose utilization was also significantly increased in heterozygous mice compared with that in wild‐type mice in olfactory cortex. These data might reflect hyperdopaminergic activity, olfactory deficits, and sleep disturbances in STOP‐KO mice that have also been reported in schizophrenic patients. © 2007 Wiley‐Liss, Inc.
Discoidin domain receptor 1 mediates collagen‐induced inflammatory activation of microglia in culture
Authors: Seo Min‐Chul , Kim Sangseop , Kim Sang‐Hyun , Zheng Long Tai , Park Eui Kyun , Lee Won‐Ha , Suk Kyoungho 
Published: October 2007

AbstractDiscoidin domain receptor 1 (DDR1) is a nonintegrin collagen receptor tyrosine kinase with an extracellular domain homologous to discoidin 1 of a soil‐living amoeba Dictyostelium discoideum. We have previously demonstrated that DDR1 mediates collagen‐induced nitric oxide production in J774A.1 murine macrophages. Because collagen is one of the main components of extracellular matrix in the central nervous system, we hypothesized that collagen also induces inflammatory activation of brain microglia, and DDR1 may mediate collagen‐induced microglial activation. Using BV‐2 mouse microglial cells and mouse primary microglial cultures, we have demonstrated that (1) collagen induces inflammatory activation of microglia as evidenced by production of nitric oxide, expression of inducible nitric oxide synthase, COX‐2, CD40, and matrix metalloproteinase–9; (2) DDR1 is expressed in microglia and is phosphorylated by collagen treatment; and (3) collagen‐induced microglial activation is abrogated by DDR1 blockade but not by integrin neutralization. We have further shown that p38 MAPK, c‐Jun N‐terminal kinase, and nuclear factor–kappa B are involved in the collagen‐DDR1‐induced microglial activation. Our results suggest that collagen can induce inflammatory activation of brain microglia and that DDR1 mediates this effect of collagen in an integrin‐independent manner. © 2007 Wiley‐Liss, Inc.
Calcium‐enriched goat milk, in comparison with similarly enriched cow milk, favours magnesium bioavailability in rats with nutritional ferropenic anaemia
Authors: Nestares Teresa , Díaz‐Castro Javier , Alférez María JM , López‐Aliaga Inmaculada , Barrionuevo Mercedes , Campos Margarita S 
Published: October 2007

AbstractBACKGROUND: The effects of dietary consumption of goat or cow milk, normal or enriched with calcium (Ca), on magnesium (Mg) bioavailability was evaluated in rats with nutritional ferropenic anaemia. Control and iron‐deficient rats were fed for 14 days with iron‐normal diets containing either normal (5000 mg kg−1 diet) or high (10 000 mg kg−1 diet) Ca content.RESULTS: The results shown that the goat milk diet gave the best results for digestive and metabolic utilization of Mg, both among the anaemic and the control group, with respect to the cow milk and standard diets. The most noteworthy result of Ca enrichment on the nutritive utilization of Mg is that it is less prejudicial in this respect when supplemented via goat milk than with cow milk or the standard diet.CONCLUSION: The results demonstrate the beneficial effects of the goat milk, normal or with double Ca, on the nutritional utilization of Mg; therefore the consumption of this type of milk for people with nutritional ferropenic anaemia can be recommended. Copyright © 2007 Society of Chemical Industry
Hyperpolarized C‐13 spectroscopic imaging of the TRAMP mouse at 3T—Initial experience
Authors: Chen Albert P. , Albers Mark J. , Cunningham Charles H. , Kohler Susan J. , Yen Yi‐Fen , Hurd Ralph E. , Tropp James , Bok Robert , Pauly John M. , Nelson Sarah J. , Kurhanewicz John , Vigneron Daniel B. 
Published: October 2007

AbstractThe transgenic adenocarcinoma of mouse prostate (TRAMP) mouse is a well‐studied murine model of prostate cancer with histopathology and disease progression that mimic the human disease. To investigate differences in cellular bioenergetics between normal prostate epithelial cells and prostate tumor cells, in vivo MR spectroscopic (MRS) studies with non‐proton nuclei, such as 13C, in the TRAMP model would be extremely useful. The recent development of a method for retaining dynamic nuclear polarization (DNP) in solution permits high signal‐to‐noise ratio (SNR) 13C MRI or MRSI data to be obtained following injection of a hyperpolarized 13C agent. In this transgenic mouse study, this method was applied using a double spin‐echo (DSE) pulse sequence with a small‐tip‐angle excitation RF pulse, hyperbolic‐secant refocusing pulses, and a flyback echo‐planar readout trajectory for fast (10–14 s) MRSI of 13C pyruvate (pyr) and its metabolic products at 0.135 cm3 nominal spatial resolution. Elevated 13C lactate (lac) was observed in both primary and metastatic tumors, demonstrating the feasibility of studying cellular bioenergetics in vivo with DNP hyperpolarized 13C MRSI. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Obtaining blood oxygenation levels from MR signal behavior in the presence of single venous vessels
Authors: Sedlacik Jan , Rauscher Alexander , Reichenbach Jürgen R. 
Published: October 2007

AbstractThe MR signal decay in gradient echo sequences includes signal loss due to spin dephasing caused by static magnetic field inhomogeneities. This decay can be calculated for different geometries of the susceptibility distribution, such as spheres, cylinders, or cylinder networks. In particular, the model of an infinitely long cylinder is a good approximation for single straight blood vessels. Blood oxygenation and blood volume fraction are important parameters, which influence the signal in a characteristic way. In this work the signal decays for a single cylindrical vessel were investigated and evaluated in simulations, phantom measurements as well as in vivo measurements of small single veins in the human brain by using a 3D multiecho gradient echo sequence. Good agreement between simulations and phantom experiments was obtained for different experimental settings. Based on the simulations, physiologically consistent values of venous blood oxygenation level, Y, were extracted from the in vivo measurements of different veins and volunteers (Y = 0.55 ± 0.02). The methods ability to measure changes in venous blood oxygenation induced by carbogen breathing was demonstrated in one volunteer, where an increase from Y ≈ 0.5 to Y ≈ 0.7 was observed. Magn Reson Med 58:1035–1044, 2007. © 2007 Wiley‐Liss, Inc.
SENSE phase‐constrained magnitude reconstruction with iterative phase refinement
Authors: Lew Calvin , Pineda Angel R. , Clayton David , Spielman Dan , Chan Frandics , Bammer Roland 
Published: October 2007

AbstractConventional sensitivity encoding (SENSE) reconstruction is based on equations in the complex domain. However, for many MRI applications only the magnitude is relevant. If there exists an estimate of the underlying phase information, a magnitude‐only phase‐constrained reconstruction can help to improve the conditioning of the SENSE reconstruction problem. Consequently, this reduces g‐factor‐related noise enhancement. In previous attempts at phase‐constrained SENSE reconstruction, image quality was hampered by strong aliasing artifacts resulting from inadequate phase estimates and high sensitivity to phase errors. If a full‐resolution phase image is used, a significant reduction in aliasing errors and better noise properties compared to SENSE can be obtained. An iterative scheme that improves the phase estimate to better approximate the phase is presented. The mathematical framework of the new approach is provided together with comparisons of conventional SENSE, phase‐constrained SENSE, and the new phase‐refinement method. Both theory and experimental verification demonstrate significantly better noise performance at high reduction factors, i.e., close to the theoretical limit. For applications that need only magnitude data, an iterative phase‐constrained SENSE reconstruction can provide substantial SNR improvement over SENSE reconstruction and less artifacts than phase‐constrained SENSE. Magn Reson Med 58:910–921, 2007. © 2007 Wiley‐Liss, Inc.
k‐t2BLAST: Exploiting spatiotemporal structure in simultaneously cardiac and respiratory time‐resolved volumetric imaging
Authors: Sigfridsson Andreas , Wigström Lars , Kvitting John‐Peder Escobar , Knutsson Hans 
Published: October 2007

AbstractMultidimensional imaging resolving both the cardiac and respiratory cycles simultaneously has the potential to describe important physiological interdependences between the heart and pulmonary processes. A fully five‐dimensional acquisition with three spatial and two temporal dimensions is hampered, however, by the long acquisition time and low spatial resolution. A technique is proposed to reduce the scan time substantially by extending thek‐tBLAST framework to two temporal dimensions. By sampling thek‐tspace sparsely in a lattice grid, the signal in the transform domain,x‐fspace, can be densely packed, exploiting the fact that large regions in the field of view have low temporal bandwidth. A volumetric online prospective triggering approach with full cardiac and respiratory cycle coverage was implemented. Retrospective temporal interpolation was used to refine the timing estimates for the center ofk‐space, which is sampled for all cardiac and respiratory time frames. This resulted in reduced reconstruction error compared with conventionalk‐tBLAST reconstruction. Thek‐t2BLAST technique was evaluated by decimating a fully sampled five‐dimensional data set, and feasibility was further demonstrated by performing sparsely sampled acquisitions. Compared to the fully sampled data, a fourfold improvement in spatial resolution was accomplished in approximately half the scan time. Magn Reson Med 58:922–930, 2007. © 2007 Wiley‐Liss, Inc.
Wideband SSFP: Alternating repetition time balanced steady state free precession with increased band spacing
Authors: Nayak Krishna S. , Lee Hsu‐Lei , Hargreaves Brian A. , Hu Bob S. 
Published: October 2007

AbstractBalanced steady‐state free precession (SSFP) imaging is limited by off‐resonance banding artifacts, which occur with periodicity 1/TR in the frequency spectrum. A novel balanced SSFP technique for widening the band spacing in the frequency response is described. This method, called wideband SSFP, utilizes two alternating repetition times with alternating RF phase, and maintains high SNR and T2/T1 contrast. For a fixed band spacing, this method can enable improvements in spatial resolution compared to conventional SSFP. Alternatively, for a fixed readout duration this method can widen the band spacing, and potentially avoid the banding artifacts in conventional SSFP. The method is analyzed using simulations and phantom experiments, and is applied to the reduction of banding artifacts in cine cardiac imaging and high‐resolution knee imaging at 3T. Magn Reson Med 58:931–938, 2007. © 2007 Wiley‐Liss, Inc.
3He MRI in mouse models of asthma
Authors: Driehuys Bastiaan , Walker Julia , Pollaro Jim , Cofer Gary P. , Mistry Nilesh , Schwartz David , Johnson G. Allan 
Published: October 2007

AbstractIn the study of asthma, a vital role is played by mouse models, because knockout or transgenic methods can be used to alter disease pathways and identify therapeutic targets that affect lung function. Assessment of lung function in rodents by available methods is insensitive because these techniques lack regional specificity. A more sensitive method for evaluating lung function in human asthma patients uses hyperpolarized (HP) 3He MRI before and after bronchoconstriction induced by methacholine (MCh). We now report the ability to perform such 3He imaging of MCh response in mice, where voxels must be ∼3000 times smaller than in humans and 3He diffusion becomes an impediment to resolving the airways. We show three‐dimensional (3D) images that reveal airway structure down to the fifth branching and visualize ventilation at a resolution of 125 × 125 × 1000 μm3. Images of ovalbumin (OVA)‐sensitized mice acquired after MCh show both airway closure and ventilation loss. To also observe the MCh response in naive mice, we developed a non‐slice‐selective 2D protocol with 187 × 187 μm2 resolution that was fast enough to record the MCh response and recovery with 12‐s temporal resolution. The extension of 3He MRI to mouse models should make it a valuable translational tool in asthma research. Magn Reson Med 58:893–900, 2007. © 2007 Wiley‐Liss, Inc.
Axonal damage in the spinal cord of multiple sclerosis patients detected by magnetic resonance spectroscopy
Authors: Blamire Andrew M. , Cader Sarah , Lee Martin , Palace Jackie , Matthews Paul M. 
Published: October 2007

AbstractAxonal damage is a major factor contributing to permanent disability in patients with multiple sclerosis (MS); it has been extensively investigated in the brain using magnetic resonance spectroscopy (MRS). In this study, MRS was used to investigate the degree of neuronal damage in the cervical spinal cord in MS. Spectra were acquired from spinal cord and brain in 11 patients with MS (expanded disability status score [EDSS], range 2.5–7.0) and 11 controls. Brain lesion volume and spinal cord cross‐sectional area were measured. Concentration of the neuronal metabolite N‐acetyl‐aspartate ([NAA]) was reduced in the spinal cord in MS patients relative to controls (reduced by 32%, P < 0.05), indicating significant neuronal damage. Additionally, the spinal cord was significantly atrophied in MS patients (15%, P < 0.001). No significant reduction in brain [NAA] was seen in the MS group. There were no correlations between clinical measures and cord atrophy or brain lesion volume on MRI; however, spinal cord [NAA] correlated with the cerebellar subscore of the neurological assessment (P < 0.005), while brain [NAA] correlated with disease duration (P < 0.05). MRS demonstrated cellular damage within the cord over and above the tissue atrophy seen by MRI. Combining MRI and MRS may therefore give a more complete picture of neurodegeneration in the spinal cord. Magn Reson Med 58:880–885, 2007. © 2007 Wiley‐Liss, Inc.
Optimized T1‐weighted contrast for single‐slab 3D turbo spin‐echo imaging with long echo trains: Application to whole‐brain imaging
Authors: Park Jaeseok , Mugler John P. , Horger Wilhelm , Kiefer Berthold 
Published: October 2007

AbstractT1‐weighted contrast is conventionally obtained using multislice two‐dimensional (2D) spin‐echo (SE) imaging. Achieving isotropic, high spatial resolution is problematic with conventional methods due to a long acquisition time, imperfect slice profiles, or high‐energy deposition. Single‐slab 3D SE imaging was recently developed employing long echo trains with variable low flip angles to address these problems. However, long echo trains may yield suboptimal T1‐weighted contrast, since T2 weighting of the signals tends to develop along the echo train. Image blurring may also occur if high spatial frequency signals are acquired with low signal intensity. The purpose of this work was to develop an optimized T1‐weighted version of single‐slab 3D SE imaging with long echo trains. Refocusing flip angles were calculated based on a tissue‐specific prescribed signal evolution. Spatially nonselective excitation was used, followed by half‐Fourier acquisition in the in‐plane phase encoding (PE) direction. Restore radio frequency (RF) pulses were applied at the end of the echo train to optimize T1‐weighted contrast. Imaging parameters were optimized by using Bloch equation simulation, and imaging studies of healthy subjects were performed to investigate the feasibility of whole‐brain imaging with isotropic, high spatial resolution. The proposed technique permitted highly‐efficient T1‐weighted 3D SE imaging of the brain. Magn Reson Med 58:982–992, 2007. © 2007 Wiley‐Liss, Inc.
Tracer kinetic model–driven registration for dynamic contrast‐enhanced MRI time‐series data
Authors: Buonaccorsi Giovanni A. , O'Connor James P.B. , Caunce Angela , Roberts Caleb , Cheung Sue , Watson Yvonne , Davies Karen , Hope Lynn , Jackson Alan , Jayson Gordon C. , Parker Geoffrey J.M. 
Published: October 2007

AbstractDynamic contrast‐enhanced MRI (DCE‐MRI) time series data are subject to unavoidable physiological motion during acquisition (e.g., due to breathing) and this motion causes significant errors when fitting tracer kinetic models to the data, particularly with voxel‐by‐voxel fitting approaches. Motion correction is problematic, as contrast enhancement introduces new features into postcontrast images and conventional registration similarity measures cannot fully account for the increased image information content. A methodology is presented for tracer kinetic model–driven registration that addresses these problems by explicitly including a model of contrast enhancement in the registration process. The iterative registration procedure is focused on a tumor volume of interest (VOI), employing a three‐dimensional (3D) translational transformation that follows only tumor motion. The implementation accurately removes motion corruption in a DCE‐MRI software phantom and it is able to reduce model fitting errors and improve localization in 3D parameter maps in patient data sets that were selected for significant motion problems. Sufficient improvement was observed in the modeling results to salvage clinical trial DCE‐MRI data sets that would otherwise have to be rejected due to motion corruption. Magn Reson Med 58:1010–1019, 2007. © 2007 Wiley‐Liss, Inc.
Refining the sensory and motor ratunculus of the rat upper extremity using fMRI and direct nerve stimulation
Authors: Cho Younghoon R. , Pawela Christopher P. , Li Rupeng , Kao Dennis , Schulte Marie L. , Runquist Matthew L. , Yan Ji‐Geng , Matloub Hani S. , Jaradeh Safwan S. , Hudetz Anthony G. , Hyde James S. 
Published: October 2007

AbstractIt is well understood that the different regions of the body have cortical representations in proportion to the degree of innervation. Our current understanding of the rat upper extremity has been enhanced using functional MRI (fMRI), but these studies are often limited to the rat forepaw. The purpose of this study is to describe a new technique that allows us to refine the sensory and motor representations in the cerebral cortex by surgically implanting electrodes on the major nerves of the rat upper extremity and providing direct electrical nerve stimulation while acquiring fMRI images. This technique was used to stimulate the ulnar, median, radial, and musculocutaneous nerves in the rat upper extremity using four different stimulation sequences that varied in frequency (5 Hz vs. 10 Hz) and current (0.5 mA vs. 1.0 mA). A distinct pattern of cortical activation was found for each nerve. The higher stimulation current resulted in a dramatic increase in the level of cortical activation. The higher stimulation frequency resulted in both increases and attenuation of cortical activation in different regions of the brain, depending on which nerve was stimulated. Magn Reson Med 58:901–909, 2007. © 2007 Wiley‐Liss, Inc.
Three‐dimensional J‐resolved H‐1 magnetic resonance spectroscopic imaging of volunteers and patients with brain tumors at 3T
Authors: Li Yan , Chen Albert P. , Crane Jason C. , Chang Susan M. , Vigneron Daniel B. , Nelson Sarah J. 
Published: October 2007

AbstractA method that combines two‐dimensional (2D) J‐resolved spectroscopy with three spatial dimension magnetic resonance spectroscopic imaging (MRSI) is introduced to measure J‐coupled metabolites of glutamate (Glu), glutamine (Gln), myo‐Inositol (mI), and lactate (Lac) in the brain and to simultaneously obtain T2 values of choline (Cho), creatine (Cr), and N‐acetyl aspartate (NAA). Relatively few points in the t1 dimension (six echo times) and a flyback echo‐planar trajectory were incorporated in the acquisition to speed up the total acquisition time so that it was within a clinically feasible range (23 min). Data obtained using GAMMA software simulations and from phantoms have shown that the 4CH2 resonances of Glu can be separated from Gln at 2.35 ppm in TE‐averaged spectra. Results from phantoms, six normal volunteers, and four patients demonstrated good signal‐to‐noise ratio (SNR). The J cross‐peaks from the methyl group of Lac were visualized in the 2D spectra from the phantom and the glioma patient, and could be quantified from the spectra at J = ±4.17 Hz. This technique also enables the evaluation of the changes in metabolite T2. Compared with the values in normal white matter, the T2 values of Cho and Cr were statistically significantly increased in regions of glioma. Magn Reson Med 58:886–892, 2007. © 2007 Wiley‐Liss, Inc.