bluuebunny/crossref_metadata_2025_split huggingface dataset:
NMDA receptor–dependent signaling pathways that underlie amyloid β‐protein disruption of LTP in the hippocampus
Authors: Yamin Ghiam 
Published: January 2009

AbstractAlzheimer's disease (AD), the most common neurodegenerative disease in the elderly population, is characterized by the hippocampal deposition of fibrils formed by amyloid β‐protein (Aβ), a 40‐ to 42‐amino‐acid peptide. The folding of Aβ into neurotoxic oligomeric, protofibrillar, and fibrillar assemblies is believed to mediate the key pathologic event in AD. The hippocampus is especially susceptible in AD and early degenerative symptoms include significant deficits in the performance of hippocampal‐dependent cognitive abilities such as spatial learning and memory. Transgenic mouse models of AD that express C‐terminal segments or mutant variants of amyloid precursor protein, the protein from which Aβ is derived, exhibit age‐dependent spatial memory impairment and attenuated long‐term potentiation (LTP) in the hippocampal CA1 and dentate gyrus (DG) regions. Recent experimental evidence suggests that Aβ disturbs N‐methyl‐D‐aspartic acid (NMDA) receptor–dependent LTP induction in the CA1 and DG both in vivo and in vitro. Furthermore, these studies suggest that Aβ specifically interferes with several major signaling pathways downstream of the NMDA receptor, including the Ca2+‐dependent protein phosphatase calcineurin, Ca2+/calmodulin‐dependent protein kinase II (CaMKII), protein phosphatase 1, and cAMP response element–binding protein (CREB). The influence of Aβ on each of these downstream effectors of the NMDA receptor is reviewed in this article. Additionally, other mechanisms of LTP modulation, such as Aβ attenuation of α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazolepropionic acid (AMPA) receptor currents, are briefly discussed. © 2009 Wiley‐Liss, Inc.
Disposition of axonal caspr with respect to glial cell membranes: Implications for the process of myelination
Authors: Pedraza Liliana , Huang Jeffrey K. , Colman David 
Published: January 2009

AbstractNeurofascin‐155 (NF155) and caspr are transmembrane proteins found at discrete locations early during development of the nervous system. NF155 is present in the oligodendrocyte cell body and processes, whereas caspr is on the axonal surface. In mature nerves, these proteins are clustered at paranodes, flanking the node of Ranvier. To understand how NF155 and caspr become localized to the paranodal regions of myelinated nerves, we have studied their distribution over time in myelinating cultures. Our observations indicate that these two proteins are recruited to the cell surface at the contact zone between axons and oligodendrocytes, where they trans‐interact. This association explains the early pattern of caspr distribution, a helical coil that winds around the axon, resembling the turns of the myelin sheath. Caspr, an axonal membrane protein, therefore seems to move in register with the overlying myelinating cell via its interactions with myelin proteins. We suggest that NF155 is the glial cell membrane protein responsible for caspr distribution. The pair act as interacting partners on either side of the axoglial contact area. Most likely, there are other proteins on the axonal surface whose distribution is equally influenced by interaction with the nascent myelin sheath. The fact that caspr follows the movement of the spiraling membrane has a direct affect on the interpretation of the way in which myelin is formed. © 2009 Wiley‐Liss, Inc.
The SNARE protein SNAP‐29 interacts with the GTPase Rab3A: Implications for membrane trafficking in myelinating glia
Authors: Schardt Anke , Brinkmann Bastian G. , Mitkovski Miso , Sereda Michael W. , Werner Hauke B. , Nave Klaus‐Armin 
Published: January 2009

AbstractDuring myelin formation, vast amounts of specialized membrane proteins and lipids are trafficked toward the growing sheath in cell surface‐directed transport vesicles. Soluble N‐ethylmaleimide‐sensitive factor (NSF) attachment proteins (SNAPs) are important components of molecular complexes required for membrane fusion. We have analyzed the expression profile and molecular interactions of SNAP‐29 in the nervous system. In addition to its known enrichment in neuronal synapses, SNAP‐29 is abundant in oligodendrocytes during myelination and in noncompact myelin of the peripheral nervous system. By yeast two‐hybrid screen and coimmunoprecipitation, we found that the GTPases Rab3A, Rab24, and septin 4 bind to the N‐terminal domain of SNAP‐29. The interaction with Rab24 or septin 4 was GTP independent. In contrast, interaction between SNAP‐29 and Rab3A was GTP dependent, and colocalization was extensive both in synapses and in myelinating glia. In HEK293 cells, cytoplasmic SNAP‐29 pools were redistributed upon coexpression with Rab3A, and surface‐directed trafficking of myelin proteolipid protein was enhanced by overexpression of SNAP‐29 and Rab3A. Interestingly, the abundance of SNAP‐29 in sciatic nerves was increased during remyelination and in a rat model of Charcot‐Marie‐Tooth disease, two pathological situations with increased myelin membrane biogenesis. We suggest that Rab3A may regulate SNAP‐29‐mediated membrane fusion during myelination. © 2009 Wiley‐Liss, Inc.
Deprivation‐induced dendritic shrinkage might be oppositely affected by the expression of wild‐type and mutated human amyloid precursor protein
Authors: Alpár Alán , Naumann Nicole , Ueberham Uwe , Arendt Thomas , Gärtner Ulrich 
Published: January 2009

AbstractThe physiological role of the amyloid precursor protein (APP) and its proteolytic fragments in the brain is associated with neuronal survival, neurite outgrowth, synaptic formation, and neuronal plasticity. However, malregulation of APP processing leads to disordered balance of fragments, which may results in opposite, degenerative neuronal effects. In the present study, we analyzed in vivo effects of the expression of wild‐type or mutated human APP on afferent deprivation‐induced changes of dendritic morphology. After vibrissectomy, expression of wild‐type human APP prevented diameter shrinkage of dendritic segments as well as dendritic rarefaction of apical arbors. In contrast, mutant human APP expression exacerbated degenerative changes of deprived barrel neurons. Degradation of apical arbors was especially pronounced. Results demonstrate for the first time opposite effects of the expression of wild‐type and mutated human APP on deprivation‐induced dendritic restructuring in vivo. © 2009 Wiley‐Liss, Inc.
Multilevel lateral extra‐cavitary corpectomy and reconstruction for non‐contiguous metastatic lesions to the spine: Case report and literature review
Authors: Keshavarzi Sassan , Aryan Henry E. 
Published: January 2009

AbstractIn patients with metastatic disease to their spine and compromise of neurologic function, the challenge is to accomplish decompression of the neural elements and maintain mechanical stability but limit the risk and morbidity to the patient. In this case report the lateral extracavitary approach is employed to accomplish these tasks through a single approach in a patient with multiple non‐contiguous sites of dorsal as well as ventral cord compression. J. Surg. Oncol. 2009;99:314–317. © 2009 Wiley‐Liss, Inc.
Neurotrophic receptor, tropomyosin‐related kinase B as an independent prognostic marker in gastric cancer patients
Authors: Tanaka Koji , Mohri Yasuhiko , Nishioka Junji , Kobayashi Minako , Ohi Masaki , Miki Chikao , Tonouchi Hitoshi , Nobori Tsutomu , Kusunoki Masato 
Published: January 2009

AbstractBackground and ObjectivesNeurotrophic receptor tyrosine kinase TrkB has been associated with clinical outcome and chemotherapy resistance in neuroblastoma and certain human malignancies. Recent studies have focused on the association between metastatic potential and TrkB expression in tumor cells.MethodsTo determine the role of TrkB in gastric cancer, we analyzed TrkB mRNA levels by real‐time reverse transcription polymerase chain reaction in 90 patients with gastric cancer. TrkB levels were correlated with clinicopathological variables. The association between TrkB and overall survival was evaluated by univariate and multivariate analyses.ResultsThe mean TrkB level in gastric cancer tissue was 2.96 (range, 0–27.1). Thirty‐eight (42%) of 90 patients showed detectable TrkB levels, whereas the remainder had no detectable TrkB. There was no significant association between clinicopathological variables and TrkB positivity. TrkB level was significantly associated with extent of lymph node metastasis in node positive patients (P = 0.03). TrkB positivity (n = 38) was significantly correlated with worse patient survival (P = 0.03). Multivariate analysis showed TrkB to be an independent prognostic parameter for overall survival (P = 0.04).ConclusionsTrkB is an independent prognostic marker in patients with gastric cancer and appears to be associated with metastatic potential. J. Surg. Oncol. 2009;99:307–310. © 2009 Wiley‐Liss, Inc.
Identification and expression profiling of microRNAs during bovine oocyte maturation using heterologous approach
Authors: Tesfaye Dawit , Worku Dagnachew , Rings Franca , Phatsara Chirawath , Tholen Ernst , Schellander Karl , Hoelker Michael 
Published: January 2009

AbstractThe accumulation of maternal mRNA and protein during oogenesis for supporting oocyte maturation and the newly fertilised zygote marks the beginning of developmental process in mammals. MicroRNAs (∼18–22 nt long) which are known for post‐transcriptional gene regulation are evidenced for their essential role during animal development. We, therefore, aimed to investigate the expression of miRNAs in immature and in vitro matured bovine oocytes, using heterologous miRNA array platform. To attain this, we used a mercury™ locked nucleic acids (LNA) array (Exiqon, Vedbaek, Denmark) microarray that consist of 454 capture probes for human, mouse and rat miRNAs as registered and annotated in the miRBase release 8.0 at The Wellcome Trust Sanger Institute. Our result revealed the differential expression of 59 miRNAs, of which 31 and 28 miRNAs were found to be preferentially expressed in immature and matured oocytes, respectively. Here, we also report the identification of 32 orthologous miRNAs using a heterologous approach. Expression profiling of selected miRNAs during preimplantation stage embryos showed a distinct temporal expression pattern. After target prediction for selected candidate miRNAs high ranking target mRNA were quantified in immature and matured oocytes and showed a reciprocal expression pattern between the miRNA and the predicted targets suggesting a cause and effect relationship. Mol. Reprod. Dev. 76: 665–677, 2009. © 2009 Wiley‐Liss, Inc.
Magnetic field correlation as a measure of iron‐generated magnetic field inhomogeneities in the brain
Authors: Jensen Jens H. , Szulc Kamila , Hu Caixia , Ramani Anita , Lu Hanzhang , Xuan Liang , Falangola Maria F. , Chandra Ramesh , Knopp Edmond A. , Schenck John , Zimmerman Earl A. , Helpern Joseph A. 
Published: January 2009

AbstractThe magnetic field correlation (MFC) at an applied field level of 3 Tesla was estimated by means of MRI in several brain regions for 21 healthy human adults and 1 subject with aceruloplasminemia. For healthy subjects, highly elevated MFC values compared with surrounding tissues were found within the basal ganglia. These are argued as being primarily the result of microscopic magnetic field inhomogeneities generated by nonheme brain iron. The MFC in the aceruloplasminemia subject was significantly higher than for healthy adults in the globus pallidus, thalamus and frontal white matter, consistent with the known increased brain iron concentration associated with this disease. Magn Reson Med 61:481–485, 2009. © 2009 Wiley‐Liss, Inc.
Gradient moment compensated magnetic resonance spectroscopic imaging
Authors: Kim Dong‐Hyun , Gu Meng , Spielman Daniel M. 
Published: January 2009

AbstractSpectroscopic imaging applications outside of the brain can suffer from artifacts due to inherent long scan times and susceptibility to motion. A fast spectroscopic imaging sequence has been devised with reduced sensitivity to motion. The sequence uses oscillating readout gradients and acquires k‐space data in a spiral out–in fashion, which allows fast k‐space coverage. We show that a spiral out–in readout acquisition is characterized by small gradient moments, reducing sensitivity to motion‐induced artifacts. Data are acquired comparing the sequence to normal phase encoded spectroscopic imaging and conventional spiral spectroscopic imaging protocols. In addition, in vivo data are acquired from the liver, demonstrating potential usage as a multivoxel fat/water spectroscopic imaging tool. Results indicate that in the presence of motion, ghosting effects are reduced while metabolite signal increases of approximately 10% can be achieved. Magn Reson Med 61:457–461, 2009. © 2009 Wiley‐Liss, Inc.
Broadband slab selection with B mitigation at 7T via parallel spectral‐spatial excitation
Authors: Setsompop Kawin , Alagappan Vijayanand , Gagoski Borjan A. , Potthast Andreas , Hebrank Franz , Fontius Ulrich , Schmitt Franz , Wald L.L. , Adalsteinsson E. 
Published: January 2009

AbstractChemical shift imaging benefits from signal‐to‐noise ratio (SNR) and chemical shift dispersion increases at stronger main field such as 7 Tesla, but the associated shorter radiofrequency (RF) wavelengths encountered require B mitigation over both the spatial field of view (FOV) and a specified spectral bandwidth. The bandwidth constraint presents a challenge for previously proposed spatially tailored B mitigation methods, which are based on a type of echovolumnar trajectory referred to as “spokes” or “fast‐kz”. Although such pulses, in conjunction with parallel excitation methodology, can efficiently mitigate large B inhomogeneities and achieve relatively short pulse durations with slice‐selective excitations, they exhibit a narrow‐band off‐resonance response and may not be suitable for applications that require B mitigation over a large spectral bandwidth. This work outlines a design method for a general parallel spectral‐spatial excitation that achieves a target‐error minimization simultaneously over a bandwidth of frequencies and a specified spatial‐domain. The technique is demonstrated for slab‐selective excitation with in‐plane B mitigation over a 600‐Hz bandwidth. The pulse design method is validated in a water phantom at 7T using an eight‐channel transmit array system. The results show significant increases in the pulse's spectral bandwidth, with no additional pulse duration penalty and only a minor tradeoff in spatial B mitigation compared to the standard spoke‐based parallel RF design. Magn Reson Med 61:493–500, 2009. © 2009 Wiley‐Liss, Inc.
Parallel spectroscopic imaging reconstruction with arbitrary trajectories using k‐space sparse matrices
Authors: Gu Meng , Liu Chunlei , Spielman Daniel M. 
Published: January 2009

AbstractParallel imaging reconstruction has been successfully applied to magnetic resonance spectroscopic imaging (MRSI) to reduce scan times. For undersampled k‐space data on a Cartesian grid, the reconstruction can be achieved in image domain using a sensitivity encoding (SENSE) algorithm for each spectral data point. Alternative methods for reconstruction with undersampled Cartesian k‐space data are the SMASH and GRAPPA algorithms that do the reconstruction in the k‐space domain. To reconstruct undersampled MRSI data with arbitrary k‐space trajectories, image‐domain‐based iterative SENSE algorithm has been applied at the cost of long computing times. In this paper, a new k‐space domain‐based parallel spectroscopic imaging reconstruction with arbitrary k‐space trajectories using k‐space sparse matrices is applied to MRSI with spiral k‐space trajectories. The algorithm achieves MRSI reconstruction with reduced memory requirements and computing times. The results are demonstrated in both phantom and in vivo studies. Spectroscopic images very similar to that reconstructed with fully sampled spiral k‐space data are obtained at different reduction factors. Magn Reson Med 61:267–272, 2009. © 2009 Wiley‐Liss, Inc.
Nonlinear ΔR effects in perfusion quantification using bolus‐tracking MRI
Authors: Calamante Fernando , Connelly Alan , van Osch Matthias J.P. 
Published: January 2009

AbstractDynamic susceptibility contrast MRI involves injection of a contrast agent, whose concentration is estimated from ΔR changes. However, measurement of contrast‐agent concentration is prone to various sources of error; in particular, the commonly assumed linear relationship between contrast agent concentration and ΔR in arterial blood is known to be invalid. In this study, we characterized the associated perfusion errors. Large errors were found when the linear assumption is used; these errors were highly dependent on the choice of tissue relaxivity. The errors were greatly reduced when using the quadratic model, and were further reduced when quantifying perfusion as a relative measure. This study suggests the linear assumption should be abandoned in favor of the quadratic model. Thus, the errors are minimized leading to improved quantification that will enable perfusion MRI to continue to play an important role in quantifying perfusion in brain diseases (e.g., acute stroke). Magn Reson Med 61:486–492, 2009. © 2009 Wiley‐Liss, Inc.
Lung morphology assessment using MRI: A robust ultra‐short TR/TE 2D steady state free precession sequence used in cystic fibrosis patients
Authors: Failo Riccarda , Wielopolski Piotr A. , Tiddens Harm A.W.M. , Hop Wim C.J. , Pozzi Mucelli Roberto , Lequin Maarten H. 
Published: January 2009

AbstractTo evaluate feasibility and diagnostic quality of ultra‐short TR/TE two‐dimensional (2D) steady state free precession (SSFP) MRI for cystic fibrosis (CF) patients. We performed lung MRI at 1.5 Tesla in 20 CF‐patients (6–17 years, 12 males). Axial, coronal, and sagittal sections were acquired in inspiration and expiration with maximum breath‐hold time 10 s. MR and CT images were scored using a modified Brody scoring system to assess bronchiectasis, mucous plugging, atelectasis/consolidations, and air trapping. All images were scored by two experienced observers. A complete MR investigation took maximally 15 min. Maximal breath‐holds were only 10 s and well tolerated. MRI identified major bronchiectasis, mucous plugging and atelectasis. End‐expiratory scans showed patches of parenchyma with reduced signal intensity that may corresponded to areas of trapped air on expiratory CT scans. This MRI protocol based on ultra‐short TR/TE 2D SSFP is quick and well tolerated and provides highly relevant imaging features as seen on CT in CF patients. Most importantly, the SNR of the expiratory scans enables to visualize air trapping. The preliminary results of this study suggest MRI as a noteworthy additional imaging tool for routine monitoring of CF patients. Magn Reson Med 61:299–306, 2009. © 2009 Wiley‐Liss, Inc.
Quantitative magnetization transfer measured pool‐size ratio reflects optic nerve myelin content in ex vivo mice
Authors: Ou Xiawei , Sun Shu‐Wei , Liang Hsiao‐Fang , Song Sheng‐Kwei , Gochberg Daniel F. 
Published: January 2009

AbstractOptic nerves from mice that have undergone retinal ischemia were examined using a newly implemented quantitative magnetization transfer (qMT) technique. Previously published results indicate that the optic nerve from retinal ischemia mice suffered significant axon degeneration without detectable myelin injury at 3 days after reperfusion. At this time point, we acquired ex vivo qMT parameters from both shiverer mice (which have nearly no myelin) and control mice that have undergone retinal ischemia, and these qMT measures were compared with diffusion tensor imaging (DTI) results. Our findings suggests that the qMT estimated ratio of the pool sizes of the macromolecular and free water protons reflected the different myelin contents in the optic nerves between the shiverer and control mice. This pool size ratio was specific to myelin content only and was not significantly affected by the presence of axon injury in mouse optic nerve 3 days after retinal ischemia. Magn Reson Med 61:364–371, 2009. © 2009 Wiley‐Liss, Inc.
Human whole blood T2 relaxometry at 3 Tesla
Authors: Chen Jean J. , Pike G. Bruce 
Published: January 2009

AbstractA precise understanding of human blood spin–spin relaxation is of major importance for numerous applications, particularly functional magnetic resonance imaging (fMRI), which is increasingly performed at 3 Tesla. It is well known that T2 measured from partially deoxygenated blood depends on the Carr–Purcell Meiboom–Gill (CPMG) refocusing interval (τ180) and on blood oxygenation (Y), yet debate remains over the quantification of this phenomenon, primarily with respect to the accuracy of its characterization by the diffusion and fast two‐site exchange models. In this study, a detailed characterization of the deoxygenation‐induced T2 reduction in human whole blood, as well as a comprehensive assessment of the role of τ180, were performed at 3 T. The diffusion model was found to better fit the observed T2 behavior as compared with the exchange model. The estimated diffusion‐model parameters suggest the T2 decay enhancement at 3 T is due to a linear increase in the magnitude of deoxygenation‐induced field inhomogeneities with field strength. These findings also confirm the potential of τ180 manipulation in measuring changes in venous blood volume. Magn Reson Med 61:249–254, 2009. © 2009 Wiley‐Liss, Inc.
Phase‐contrast magnetic resonance imaging measurements in intracranial aneurysms in vivo of flow patterns, velocity fields, and wall shear stress: Comparison with computational fluid dynamics
Authors: Boussel Loic , Rayz Vitaliy , Martin Alastair , Acevedo‐Bolton Gabriel , Lawton Michael T. , Higashida Randall , Smith Wade S. , Young William L. , Saloner David 
Published: January 2009

AbstractEvolution of intracranial aneurysms is known to be related to hemodynamic forces such as wall shear stress (WSS) and maximum shear stress (MSS). Estimation of these parameters can be performed using numerical simulations with computational fluid dynamics (CFD), but can also be directly measured with magnetic resonance imaging (MRI) using a time‐dependent 3D phase‐contrast sequence with encoding of each of the three components of the velocity vectors (7D‐MRV). To study the accuracy of 7D‐MRV in estimating these parameters in vivo, in comparison with CFD, 7D‐MRV and patient‐specific CFD modeling was performed for 3 patients who had intracranial aneurysms. Visual and quantitative analyses of the flow pattern and distribution of velocities, MSS, and WSS were performed using the two techniques. Spearman's coefficients of correlation between the two techniques were 0.56 for the velocity field, 0.48 for MSS, and 0.59 for WSS. Visual analysis and Bland–Altman plots showed good agreement for flow pattern and velocities but large discrepancies for MSS and WSS. These results indicate that 7D‐MRV can be used in vivo to measure velocity flow fields and for estimating MSS and WSS. Currently, however, this method cannot accurately quantify the latter two parameters. Magn Reson Med 61:409–417, 2009. © 2009 Wiley‐Liss, Inc.