bluuebunny/crossref_metadata_2025_split huggingface dataset:
Molecular characterization of a human cation‐Cl− cotransporter (SLC12A8A, CCC9A) that promotes polyamine and amino acid transport
Authors: Daigle Nikolas D. , Carpentier Gabriel A. , Frenette‐Cotton Rachelle , Simard Michael G. , Lefoll Marie‐Hélène , Noël Micheline , Caron Luc , Noël Josette , Isenring Paul 
Published: May 2009

AbstractCation‐Cl− cotransporters (CCCs) belong to a large family of proteins that includes 9 isoforms, two of which have still not been ascribed a transport function (CCC8 and CCC9) while the others are all known to promote Cl−‐coupled Na+ and/or K+ movement at the cell surface. The CCCs are also included in a larger family termed amino acid‐polyamine‐organocation carriers (APCs). In contrast to the CCCs, however, polyamine (PA) transporters have thus far been isolated from unicellular species exclusively and do not all belong to the APC family. In this work, we have found that a splice variant of CCC9 (CCC9a) promotes PA‐amino acid transport at the surface of HEK‐293 cells. We have also found that the influx of PAs in CCC9a‐expressing cells is inhibited by pentamidine as well as furosemide, and that it increases further in the presence of specific amino acids but not of Na+, K+, or Cl−. Hence, a group of substrates that are directly transported by CCC9 and the molecular identity of a PA transport system in animal cells may have been uncovered for the first time. These findings are of special interest given that intracellular PAs play a key role in cell proliferation. J. Cell. Physiol. 220: 680–689, 2009. © 2009 Wiley‐Liss, Inc.
Environmental regulation of notochordal gene expression in nucleus pulposus cells
Authors: Rastogi Anshu , Thakore Pratiksha , Leung Aileen , Benavides Magda , Machado Monica , Morschauser Michael A. , Hsieh Adam H. 
Published: May 2009

AbstractCells of the nucleus pulposus (NP) in the intervertebral disc are derived directly from the embryonic notochord. In humans, a shift in NP cell population coincides with the beginning of age‐related changes in the extracellular matrix that can lead to spinal disorders. To begin identifying the bases of these changes, the manner by which relevant environmental factors impact cell function must be understood. This study investigated the roles of biochemical, nutritional, and physical factors in regulating immature NP cells. Specifically, we examined cell morphology, attachment, proliferation, and expression of genes associated with the notochord and immature NP (Sox9, CD24, and type IIA procollagen). Primary cells isolated from rat caudal discs were exposed to different media formulations and physical culture configurations either in 21% (ambient) or 2% (hypoxic) O2. As expected, cells in alginate beads retained a vacuolated morphology similar to chordocytes, with little change in gene expression. Interestingly, NP tissues not enzymatically digested were more profoundly influenced by oxygen. In monolayer, α‐MEM preserved vacuolated morphology, produced the highest efficiency of attachment, and best maintained gene expression. DMEM and Opti‐MEM cultures resulted in high levels of proliferation, but these appeared to involve small non‐vacuolated cells. Gene expression patterns for cells in DMEM monolayer cultures were consistent with chondrocyte de‐differentiation, with the response being delayed by hypoxia. Overall, results indicate that certain environmental conditions induce cellular changes that compromise the notochordal phenotype in immature NP. These results form the foundation on which the mechanisms of such changes can be elucidated. J. Cell. Physiol. 220: 698–705, 2009. © 2009 Wiley‐Liss, Inc.
Role of Rac 1 and cAMP in endothelial barrier stabilization and thrombin‐induced barrier breakdown
Authors: Baumer Y. , Spindler V. , Werthmann R.C. , Bünemann M. , Waschke J. 
Published: May 2009

AbstractBarrier stabilizing effects of cAMP as well as of the small GTPase Rac 1 are well established. Moreover, it is generally believed that permeability‐increasing mediators such as thrombin disrupt endothelial barrier functions primarily via activation of Rho A. In this study, we provide evidence that decrease of both cAMP levels and of Rac 1 activity contribute to thrombin‐mediated barrier breakdown. Treatment of human dermal microvascular endothelial cells (HDMEC) with Rac 1‐inhibitor NSC‐23766 decreased transendothelial electrical resistance (TER) and caused intercellular gap formation. These effects were reversed by addition of forskolin/rolipram (F/R) to increase intracellular cAMP but not by the cAMP analogue 8‐pCPT‐2′‐O‐Methyl‐cAMP (O‐Me‐cAMP) which primarily stimulates protein kinase A (PKA)‐independent signaling via Epac/Rap 1. However, both F/R and O‐Me‐cAMP did not increase TER above control levels in the presence of NSC‐23766 in contrast to experiments without Rac 1 inhibition. Because Rac 1 was required for maintenance of barrier functions as well as for cAMP‐mediated barrier stabilization, we tested the role of Rac 1 and cAMP in thrombin‐induced barrier breakdown. Thrombin‐induced drop of TER and intercellular gap formation were paralleled by a rapid decrease of cAMP as revealed by fluorescence resonance energy transfer (FRET). The efficacy of F/R or O‐Me‐cAMP to block barrier‐destabilizing effects of thrombin was comparable to Y27632‐induced inhibition of Rho kinase but was blunted when Rac 1 was inactivated by NSC‐23766. Taken together, these data indicate that decrease of cAMP and Rac 1 activity may be an important step in inflammatory barrier disruption. J. Cell. Physiol. 220: 716–726, 2009. © 2009 Wiley‐Liss, Inc.
Diffusion‐weighted echo‐planar magnetic resonance imaging for the assessment of tumor cellularity in patients with soft‐tissue sarcomas
Authors: Schnapauff Dirk , Zeile Martin , Niederhagen Manuel Ben , Fleige Barbara , Tunn Per‐Ulf , Hamm Bernd , Dudeck Oliver 
Published: May 2009

AbstractPurposeTo investigate the eligibility of diffusion‐weighted imaging (DWI) for the evaluation of tumor cellularity in patients with soft‐tissue sarcomas.Materials and MethodsThirty consecutive patients with a total of 31 histologically‐proven soft‐tissue sarcomas prospectively underwent magnetic resonance imaging (MRI) including DWI with echo‐planar imaging (EPI) technique immediately before open biopsy (N = 1) or tumor resection (N = 30). Fourteen patients had no previous anticancer treatment, 16 had received neoadjuvant therapy. Tumor cellularity as determined from histological sections was compared with minimum apparent diffusion coefficient (ADC).ResultsTumor cellularity correlated well with minimum ADC in a linear fashion, with a Pearson correlation coefficient of –0.88 (95% confidence interval [CI]: –0.75 to –0.96). This relationship was not influenced by prior anticancer treatment. There was only a tendency toward lower ADC in tumor with higher grading but no significant dependency (P = 0.08).ConclusionDWI has proven useful for the assessment of tumor cellularity in soft‐tissue sarcomas. In result, DWI may be used as a powerful noninvasive tool to monitor responses of cytotoxic treatment as reflected by changes in tumor cellularity. J. Magn. Reson. Imaging 2009. © 2009 Wiley‐Liss, Inc.
Optimized high‐resolution mapping of magnetization transfer (MT) at 3 Tesla for direct visualization of substructures of the human thalamus in clinically feasible measurement time
Authors: Gringel Tabea , Schulz‐Schaeffer Walter , Elolf Erck , Frölich Andreas , Dechent Peter , Helms Gunther 
Published: May 2009

AbstractPurposeTo optimize contrast‐to‐noise and spatial resolution of a FLASH‐based magnetization transfer (MT) protocol for visualization of substructures in human thalamus.Materials and MethodsHealthy adults were examined at 3 Tesla with a three‐dimensional (3D) spoiled gradient‐echo sequence. The signal‐to‐noise ratio (SNR) was increased by averaging eight bipolar echo acquisitions (mean echo time = 12.3 ms; bandwidth = 370 Hz/pixel). Three isotropic datasets with different weighting (proton density: flip angle/repetition time = 7°/30 ms; T1: 20°/30 ms and MT: 10°/48 ms, Gaussian MT prepulse) yielded maps of T1, signal amplitude, MT ratio and MT saturation for comparison to MP‐RAGE images. Measuring time was 23 min using partial k‐space acquisition. First, the SNR of MT saturation maps in thalamus was optimized by means of the excitation flip angle. Then, noise and partial volume effects were traded off by means of the resolution. Finally, the contrast within the thalamus and to adjacent structures was compared between different maps.ResultsThe optimized MT saturation maps at 0.95 mm isotropic resolution provided the highest contrast. It was most prominent between structures of high axonal content (internal medullary lamina, ventral nuclei) and those containing predominantly neuronal somata (pulvinar, mediodorsal thalamus, geniculate bodies).ConclusionSemiquantitative MT saturation maps provide an enhanced intra‐thalamic contrast. The borders and nuclear groups of the thalamus are reliably delineated; individual assignment of singular nuclei seems feasible. J. Magn. Reson. Imaging 2009;29:1285–1292. © 2009 Wiley‐Liss, Inc.
Rosette spectroscopic imaging: Optimal parameters for alias‐free, high sensitivity spectroscopic imaging
Authors: Schirda Claudiu V. , Tanase Costin , Boada Fernando E. 
Published: May 2009

AbstractPurposeTo optimize the Rosette trajectories for fast, high sensitivity spectroscopic imaging experiments and to compare this acquisition technique with other chemical shift imaging (CSI) methods.Materials and MethodsA framework for comparing the sensitivity of the Rosette Spectroscopic Imaging (RSI) acquisition to other spectroscopic imaging experiments is outlined. Accounting for hardware constraints, trajectory parameters that provide for optimal sampling and minimal artifact production are found. Along with an analytical expression for the number of excitations to be used in an RSI experiment that is provided, the theoretical precompensation weights used for optimal image reconstruction are derived.ResultsThe spectral response function for RSI is shown to be approximately the same as the point spread function of standard Fourier reconstructions. While the signal‐to‐noise ratio (SNR) for an RSI experiment is reduced by the inherent nonuniform sampling of these trajectories, their circular k‐space support and speed of spatial encoding leads to greater SNR efficiency and improvements in the total data acquisition time relative to the gold standard CSI approach with square k‐space support and to similar efficiency to spiral CSI acquisitions. Numerical simulations and in vivo experimental data are presented to demonstrate the properties of this data acquisition technique.ConclusionThis work demonstrates the use of Rosette trajectories and how to achieve improved efficiency for these trajectories in a two‐dimensional spectroscopic imaging experiment. J. Magn. Reson. Imaging 2009;29:1375–1385. © 2009 Wiley‐Liss, Inc.
Evaluation of performance metrics for bias field correction in MR brain images
Authors: Chua Zin Yan , Zheng Weili , Chee Michael W.L. , Zagorodnov Vitali 
Published: May 2009

AbstractPurposeTo investigate inconsistencies between common performance measures for bias field correction reported in several recent studies and propose a solution.Materials and MethodsA set of synthetic images of a normal brain from the Montréal Simulated Brain Database (SBD) was processed using two bias field correction algorithms. The parameters of these algorithms were varied and the resulting outputs were assessed using several performance measures. Validity was estimated using Spearman rank correlation coefficient between “indirect” performance measures and the L2 norm of the difference between true and estimated bias fields. The “indirect” performance measures tested were: coefficients of variation of white matter (WM) and gray matter (GM), coefficient of joint variation. These measures were tested on bias field‐corrected images that were permuted in terms of quality of WM/GM segmentation as well as the presence or absence of light smoothing.ResultsExisting indirect performance measures yielded poor validity scores, explaining the inconsistencies reported in the literature. Image noise and inappropriate inclusion of partial volume voxels and neighboring tissues were found to be contributory. Combining conservative segmentation and smoothing significantly improved validity.ConclusionThe use of indirect performance measures in the conventional manner to guide bias field correction is unreliable. Using these metrics on lightly smoothed images with conservatively segmented tissues proved more reliable for guiding the selecting of parameters for nonuniformity correction ultimately contributing to more accurate brain segmentation. J. Magn. Reson. Imaging 2009;29:1271–1279. © 2009 Wiley‐Liss, Inc.
Predicting survival and early clinical response to primary chemotherapy for patients with locally advanced breast cancer using DCE‐MRI
Authors: Johansen Roar , Jensen Line R. , Rydland Jana , Goa Pål E. , Kvistad Kjell A. , Bathen Tone F. , Axelson David E. , Lundgren Steinar , Gribbestad Ingrid S. 
Published: May 2009

AbstractPurposeTo evaluate dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) as a tool for early prediction of response to neoadjuvant chemotherapy (NAC) and 5‐year survival in patients with locally advanced breast cancer.Materials and MethodsDCE‐MRI was performed in patients scheduled for NAC (n = 24) before and after the first treatment cycle. Clinical response was evaluated after completed NAC. Relative signal intensity (RSI) and area under the curve (AUC) were calculated from the DCE‐curves and compared to clinical treatment response. Kohonen and probabilistic neural network (KNN and PNN) analysis were used to predict 5‐year survival.ResultsRSI and AUC were reduced after only one cycle of NAC in patients with clinical treatment response (P = 0.02 and P = 0.08). The mean and 10th percentile RSI values before NAC were significantly lower in patients surviving more than 5 years compared to nonsurvivors (P = 0.05 and 0.02). This relationship was confirmed using KNN, which demonstrated that patients who remained alive clustered in separate regions from those that died. Calibration of contrast enhancement curves by PNN for patient survival at 5 years yielded sensitivity and specificity for training and testing ranging from 80%–92%.ConclusionDCE‐MRI in locally advanced breast cancer has the potential to predict 5‐year survival in a small patient cohort. In addition, changes in tumor vascularization after one cycle of NAC can be assessed. J. Magn. Reson. Imaging 2009;29:1300–1307. © 2009 Wiley‐Liss, Inc.
Improved time‐of‐flight magnetic resonance angiography with IDEAL water‐fat separation
Authors: Grayev Allison , Shimakawa Ann , Cousins Joseph , Turski Patrick , Brittain Jean , Reeder Scott 
Published: May 2009

AbstractPurposeTo implement IDEAL (iterative decomposition of water and fat using echo asymmetry and least squares estimation) water‐fat separation with 3D time‐of‐flight (TOF) magnetic resonance angiography (MRA) of intracranial vessels for improved background suppression by providing uniform and robust separation of fat signal that appears bright on conventional TOF‐MRA.Materials and MethodsIDEAL TOF‐MRA and conventional TOF‐MRA were performed in volunteers and patients undergoing routine brain MRI/MRA on a 3T magnet. Images were reviewed by two radiologists and graded based on vessel visibility and image quality.ResultsIDEAL TOF‐MRA demonstrated statistically significant improvement in vessel visibility when compared to conventional TOF‐MRA in both volunteer and clinical patients using an image quality grading system. Overall image quality was 3.87 (out of 4) for IDEAL versus 3.55 for conventional TOF imaging (P = 0.02). Visualization of the ophthalmic artery was 3.53 for IDEAL versus 1.97 for conventional TOF imaging (P < 0.00005) and visualization of the superficial temporal artery was 3.92 for IDEAL imaging versus 1.97 for conventional TOF imaging (P < 0.00005).ConclusionBy providing uniform suppression of fat, IDEAL TOF‐MRA provides improved background suppression with improved image quality when compared to conventional TOF‐MRA methods. J. Magn. Reson. Imaging 2009;29:1367–1374. © 2009 Wiley‐Liss, Inc.
Spectral resolution amelioration by deconvolution (SPREAD) in MR spectroscopic imaging
Authors: Dong Zhengchao , Peterson Bradley S. 
Published: May 2009

AbstractPurposeTo develop, implement, and evaluate a novel postprocessing method for enhancing the spectral resolution of in vivo MR spectroscopic imaging (MRSI) data.Materials and MethodsMagnetic field inhomogeneity across the imaging volume was determined by acquiring MRI datasets with two differing echo times. The lineshapes of the MRSI spectra were derived from these field maps by simulating an MRSI scan of a virtual sample whose resonance frequencies varied according to the observed variations in the magnetic field. By deconvolving the lineshapes from the measured MRSI spectra, the linebroadening effects of the field inhomogeneities were reduced significantly.ResultsBoth phantom and in vivo proton MRSI spectra exhibited significantly enhanced spectral resolutions and improved spectral lineshapes following application of our method. Quantitative studies on a phantom show that, on average, the full width at half maximum of water peaks was reduced 42%, the full width at tenth maximum was reduced 38%, and the asymmetries of the peaks were reduced 86%.ConclusionOur method reduces the linebroadening and lineshape distortions caused by magnetic field inhomogeneities. It substantially improves the spectral resolution and lineshape of MRSI data. J. Magn. Reson. Imaging 2009;29:1395–1405. © 2009 Wiley‐Liss, Inc.
Whole heart magnetization‐prepared steady‐state free precession coronary vein MRI
Authors: Stoeck Christian T. , Han Yuchi , Peters Dana C. , Hu Peng , Yeon Susan B. , Kissinger Kraig V. , Goddu Beth , Goepfert Lois , Manning Warren J. , Kozerke Sebastian , Nezafat Reza 
Published: May 2009

AbstractPurposeTo compare two coronary vein imaging techniques using whole‐heart balanced steady‐state free precession (SSFP) and a targeted double‐oblique spoiled gradient‐echo (GRE) sequences in combination with magnetization transfer (MT) preparation sequence for tissue contrast improvement.Materials and MethodsNine healthy subjects were imaged with the proposed technique. The results are compared with optimized targeted MT prepared GRE acquisitions. Both quantitative and qualitative analyses were performed to evaluate each imaging method.ResultsWhole‐heart images were successfully acquired with no visible image artifact in the vicinity of the coronary veins. The anatomical features and visual grading of both techniques were comparable. However, the targeted small slab acquisition of the left ventricular lateral wall was superior to whole‐heart acquisition for visualization of relevant information for cardiac resynchronization therapy (CRT) lead implantation.ConclusionWe demonstrated the feasibility of whole‐heart coronary vein MRI using a 3D MT‐SSFP imaging sequence. A targeted acquisition along the lateral left ventricular wall is preferred for visualization of branches commonly used in CRT lead implantation. J. Magn. Reson. Imaging 2009;29:1293–1299. © 2009 Wiley‐Liss, Inc.
Aging effects on human calf muscle properties assessed by MRI at 3 Tesla
Authors: Schwenzer Nina F. , Martirosian Petros , Machann Jürgen , Schraml Christina , Steidle Günter , Claussen Claus D. , Schick Fritz 
Published: May 2009

AbstractPurposeTo determine age‐related changes in MR properties as T2 and T2* relaxation times, fat content, and magnetization transfer in the human calf, and comparison of these effects in different muscle groups.Materials and MethodsStudies were performed on 12 “younger” (mean, 31.2 ± 6.1 years) and 11 “older” healthy adult individuals (mean, 66.1 ± 7.8 years). The tibialis anterior muscle, the soleus muscle and the gastrocnemius muscle were examined at rest in a 3 Tesla whole‐body MR unit. T2 and T2*, muscular fat content and magnetization transfer ratios (MTR) were determined. Results of the two age groups were compared, and differences between the muscle groups were investigated.ResultsIncrease of T2 and muscular fat was detected with age with significant difference between the age groups. The extent of fatty infiltration was much more variable for the “older” group. For both age groups, the tibialis anterior muscle showed the lowest fat content with 1.2 ± 0.4% in the “young” group and 2.3 ± 0.7% in the “older” group. A strong correlation between fat content and T2 was found, while the groups did not significantly differ regarding T2*. Decrease in the MTR could only be shown for the tibialis anterior muscle with age.ConclusionAge‐related changes in healthy human calf musculature were found. Further studies might show possible correlations of age‐dependent changes with physical efficiency and susceptibility to diseases like type 2 diabetes. J. Magn. Reson. Imaging 2009;29:1346–1354. © 2009 Wiley‐Liss, Inc.
Diffusion‐weighted imaging of prostate cancer: Correlation between apparent diffusion coefficient values and tumor proliferation
Authors: Wang Xi Zhen , Wang Bin , Gao Zhi Qin , Liu Jin Gang , Liu Zuo Qin , Niu Qing Liang , Sun Zhen Kui , Yuan Yu Xiao 
Published: May 2009

AbstractPurposeTo investigate whether the apparent diffusion coefficient (ADC) values of prostate cancer (PCa) are able to reflect tumor proliferation.Materials and MethodsThe clinical and pathological information for 38 patients with PCa and 33 patients with benign prostate hyperplasia (BPH) were studied. Examination of the patients was performed using a 1.5 T superconducting magnetic scanner equipped with a pelvic phased‐array multicoil. Diffusion‐weighted images (DWIs) were acquired using an echo‐planar imaging sequence. The ADC values of PCa, BPH, and peripheral zone (PZ) were calculated. The cellularity of PCa was recorded based on hematoxylin and eosin staining. The proliferating cell nuclear antigen (PCNA) was detected using an immunohistochemical technique.ResultsThe ADC values of PCa, BPH, and PZ were 49.32 ± 12.68 × 10−5 mm2/s, 86.73 ± 26.75 × 10−5 mm2/s, and 126.25 ± 27.21 × 10−5 mm2/s, respectively. The ADC values of PCa were lower than those of BPH and PZ (P < 0.05). The cellularity and PCNA labeling index (LI) of PCa were higher than those of BPH (P < 0.05). The ADC values of PCa were negatively correlated with those of cellularity and PCNA LI (r = −0.646 and −0.446, respectively; P < 0.05).ConclusionThe ADC values of PCa can reveal the differences in proliferative activity between PCa and BPH. These values are therefore able to predict the proliferative rate of variously differentiated prostate cancers. J. Magn. Reson. Imaging 2009;29:1360–1366. © 2009 Wiley‐Liss, Inc.