bluuebunny/crossref_metadata_2025_split huggingface dataset:
Encoding and retrieval in a model of the hippocampal CA1 microcircuit
Authors: Cutsuridis Vassilis , Cobb Stuart , Graham Bruce P. 
Published: June 2009

AbstractIt has been proposed that the hippocampal theta rhythm (4–7 Hz) can contribute to memory formation by separating encoding (storage) and retrieval of memories into different functional half‐cycles (Hasselmo et al. (2002) Neural Comput 14:793–817). We investigate, via computer simulations, the biophysical mechanisms by which storage and recall of spatio‐temporal input patterns are achieved by the CA1 microcircuitry. A model of the CA1 microcircuit is presented that uses biophysical representations of the major cell types, including pyramidal (P) cells and four types of inhibitory interneurons: basket (B) cells, axo‐axonic (AA) cells, bistratified (BS) cells and oriens lacunosum‐moleculare (OLM) cells. Inputs to the network come from the entorhinal cortex (EC), the CA3 Schaffer collaterals and medial septum. The EC input provides the sensory information, whereas all other inputs provide context and timing information. Septal input provides timing information for phasing storage and recall. Storage is accomplished via a local STDP mediated hetero‐association of the EC input pattern and the incoming CA3 input pattern on the CA1 pyramidal cell target synapses. The model simulates the timing of firing of different hippocampal cell types relative to the theta rhythm in anesthetized animals and proposes experimentally confirmed functional roles for the different classes of inhibitory interneurons in the storage and recall cycles (Klausberger et al., (2003,2004) Nature 421:844–848, Nat Neurosci 7:41–47). Measures of recall performance of new and previously stored input patterns in the presence or absence of various inhibitory interneurons are employed to quantitatively test the performance of our model. Finally, the mean recall quality of the CA1 microcircuit is tested as the number of stored patterns is increased. © 2009 Wiley‐Liss, Inc.
Repeated measures of serum glucose and insulin in relation to postmenopausal breast cancer
Authors: Kabat Geoffrey C. , Kim Mimi , Caan Bette J. , Chlebowski Rowan T. , Gunter Marc J. , Ho Gloria Y.F. , Rodriguez Beatriz L. , Shikany James M. , Strickler Howard D. , Vitolins Mara Z. , Rohan Thomas E. 
Published: June 2009

AbstractExperimental and epidemiological evidence suggests that circulating glucose and insulin may play a role in breast carcinogenesis. However, few cohort studies have examined breast cancer risk in association with glucose and insulin levels, and studies to date have had only baseline measurements of exposure. We conducted a longitudinal study of postmenopausal breast cancer risk using the 6% random sample of women in the Women's Health Initiative clinical trials whose fasting blood samples, provided at baseline and at years 1, 3 and 6, were analyzed for glucose and insulin. In addition, a 1% sample of women in the observational study, who had glucose and insulin measured in fasting blood samples drawn at baseline and in year 3, were included in the analysis. We used Cox proportional hazards models to estimate hazard ratios and 95% confidence intervals for the association of baseline and follow‐up measurements of serum glucose and insulin with breast cancer risk. All statistical tests were 2‐sided. Among 5,450 women with baseline serum glucose and insulin values, 190 incident cases of breast cancer were ascertained over a median of 8.0 years of follow‐up. The highest tertile of baseline insulin, relative to the lowest, was associated with a 2‐fold increase in risk in the total population (multivariable hazard ratio 2.22, 95% confidence interval 1.39–3.53) and with a 3‐fold increase in risk in women who were not enrolled in the intervention arm of any clinical trial (multivariable hazard ratio 3.15, 95% confidence interval 1.61–6.17). Glucose levels showed no association with risk. Analysis of the repeated measurements supported the results of the baseline analysis. These data suggest that elevated serum insulin levels may be a risk factor for postmenopausal breast cancer. © 2009 UICC
EGFR and KRAS status of primary sarcomatoid carcinomas of the lung: Implications for anti‐EGFR treatment of a rare lung malignancy
Authors: Italiano Antoine , Cortot Alexis B. , Ilie Marius , Martel‐Planche Ghyslaine , Fabas Thibault , Pop Daniel , Mouroux Jérôme , Hofman Veronique , Hofman Paul , Pedeutour Florence 
Published: June 2009

AbstractSarcomatoid carcinomas (SC) of the lung are uncommon malignant tumors composed of carcinomatous and sarcomatous cell components and characterized by a more aggressive outcome than other histological subtypes of nonsmall cell lung cancer (NSCLC). Although epidermal growth factor receptor (EGFR)‐targeted therapies have emerged as a promising therapeutic approach in patients with advanced typical NSCLC such as adenocarcinoma, the potential clinical activity of these drugs in lung SC is still unknown. To investigate this point, we have analyzed the status of 4 EGFR pathways biomarkers in a series of lung SC. EGFR protein expression, EGFR gene copy number, EGFR mutational status and KRAS mutational status were assessed in a series of 22 consecutive cases of primary lung SC. EGFR protein overexpression was observed in all the cases. High level of polysomy (≥4 copies of the gene in >40% of cells) was detected in 5 cases (23%). No EGFR mutation was detected. KRAS mutations were found in 8 patients (38%; Gly12Cys in 6 cases and Gly12Val in 2 cases). The consistent EGFR protein overexpression and the high rate of KRAS mutation may contribute to the poorer outcome of lung SC in comparison with typical NSCLC. The rare incidence of increased EGFR gene copy number, the lack of EGFR mutation and the high rate of KRAS mutation observed in our series also suggest that most patients with lung SC are not likely to benefit from anti‐EGFR therapies. © 2009 UICC
Alcohol consumption and chronic atrophic gastritis: Population‐based study among 9,444 older adults from Germany
Authors: Gao Lei , Weck Melanie N. , Stegmaier Christa , Rothenbacher Dietrich , Brenner Hermann 
Published: June 2009

AbstractModerate alcohol consumption has been suggested to facilitate elimination of Helicobacter pylori infection which is a key risk factor for chronic atrophic gastritis (CAG) and gastric cancer. The aim of our study was to assess the association of alcohol consumption with CAG among older adults from Germany. In the baseline examination of ESTHER, a population‐based study conducted in Saarland, serological measurements of pepsinogen I and II (for CAG definition) and H. pylori antibodies were taken in 9,444 subjects aged 50–74 years. Moderate current (<60 g/week) and lifetime (≤51,376 g, lowest quartile) alcohol consumption were found to be associated with significantly reduced CAG risk compared to alcohol abstinence with adjusted odds ratios of 0.71 (0.55–0.90) and 0.73 (0.55–0.96), respectively. Inverse associations with CAG were observed for moderate alcohol consumption from both beer and wine, and were slightly attenuated after additional adjustment for H. pylori infection. Our results are consistent with the hypothesis that moderate alcohol consumption may be inversely related to CAG, partly through facilitating the elimination of H. pylori. However, the observed patterns suggest that other mechanisms are likely to contribute to the association as well. © 2009 UICC
Implication of groundwater fluctuation on the seasonal salt dynamic in the Harran Plain, south‐eastern Turkey
Authors: Çullu M. A. , Aydemi̇r S. , Qadi̇r M. , Almaca A. , Öztürkmen A. R. , Bi̇lgi̇ç A. , Ağca N. 
Published: June 2009

AbstractInefficient farm‐level water management aggravates groundwater fluctuation and salt accumulation particularly in arid and semi‐arid irrigated agriculture. Inappropriate water management practices in the Harran Plain are a good example. A study was carried out to investigate the effect of groundwater fluctuation on the seasonal salt dynamic in four widespread soil series in the Harran Plain with different natural drainage, south‐eastern Turkey. Four profiles were excavated and soil samples were collected seasonally up to 100 cm depth with 10 cm intervals. Similarly, irrigation and groundwater samples were collected from the fields where soil sampling was carried out. Significant seasonal variations in the salt dynamic were observed with the fluctuation levels of the groundwater. Total salt content at 1 m soil depth remained constant during the year, however salt fluctuation throughout the root zone in the growing season exceeded the threshold values of corn, wheat and cotton, commonly grown crops in the region, of 1.7, 6.0 and 7.7 dS m−1, respectively. However, soils with less water fluctuation showed lower salt accumulation in the root zone from May to October. Results also confirmed that soils can be non‐saline, but groundwater salinity, which may not be point specific, requires special attention. Copyright © 2009 John Wiley & Sons, Ltd.
The pervasive absence of compensating differentials
Authors: Bonhomme Stéphane , Jolivet Grégory 
Published: June 2009

AbstractWe study the relation between individual preferences for job amenities (e.g., type of work, job security) and compensating wage differentials in cross‐section. To this end, we estimate a partial equilibrium job search model on panel data from eight European countries. There are five non‐wage job characteristics and two sources of job‐to‐job mobility: on‐the‐job search and reallocation shocks. We also allow for two types of unobserved heterogeneity. We find strong preferences for amenities, especially job security, yet, these preferences do not translate into significant wage differentials in cross‐section. Counterfactual experiments show that one would need extremely low levels of search frictions for compensating differentials to arise. Lastly, a similar exercise on the distribution of job change outcomes reveals the role of constrained job‐to‐job mobility in the absence of compensating wage differentials. Copyright © 2009 John Wiley & Sons, Ltd.
Agricultural cycle and the prevalence of posttraumatic stress disorder: A longitudinal community study in postwar Mozambique
Authors: Igreja Victor , Kleijn Wim , Dias‐Lambranca Beatrice , Hershey Douglas A. , Calero Clara , Richters Annemiek 
Published: June 2009

AbstractThe influence of physical activity on the prevalence and remission of war‐related mental disturbances has never been systematically evaluated. This study examined the influence of participation in the agricultural cycle on the posttraumatic stress disorder (PTSD) prevalence and correlated symptoms longitudinally in postcivil war Mozambique. Prevalence rates were examined in the end and the outset of the agricultural cycle in a community population (N = 240). The agricultural cycle, which is characterized by fluctuations in physical activities, social connectedness, and the sense of purpose in life influences the PTSD prevalence and correlated symptoms. By studying the influence of the agricultural cycle on PTSD prevalence, severe PTSD cases that fail to respond to the agricultural cycle can be identified, and subsequently evaluated regarding the need for specialized care.
On the need for more precise threshold values for chloride initiated corrosion
Authors: Frederiksen J. M. 
Published: June 2009

AbstractThis paper stresses the need for focussing on a better understanding of the term ‘chloride threshold value’ for initiating reinforcement corrosion in concrete structures. It also focuses on the need for more precise values for modelling chloride ingress and for decision making in repair projects and finally on the need for a reliable internationally accepted test method for measuring the chloride threshold value. As a consequence no test results are presented. A provisional formula for design purposes and a test setup for testing the property are reintroduced.
Detecting critical chloride content in concrete using embedded ion selective electrodes – effect of liquid junction and membrane potentials
Authors: Angst U. , Vennesland Ø. 
Published: June 2009

AbstractWhen studying critical chloride content in reinforced concrete, the amount of chloride dissolved in the pore solution is an important parameter. Ion selective electrodes offer the possibility of measuring the chloride ion concentration (activity) in the concrete pore solution non‐destructively. However, the potentiometric measurement might be disturbed by, amongst others, diffusion potentials (liquid junction potentials and membrane potentials). Laboratory samples designed to find critical chloride contents often involve chloride ingress by capillary suction, diffusion or migration, and thus chloride and pH profiles are usually present. As a result of these concentration gradients, membrane potentials are established, which markedly affect the determination of the chloride concentration. In addition, liquid junction potentials at the interface of the concrete sample and the reference electrode contribute to the measured potential. Experimental observations in the present work illustrate the effect of liquid junction potentials on the application of ion selective electrodes in concrete. Moreover, the influence of internal membrane potentials has been estimated by a theoretical model.
Atmospheric corrosion of carbon steel at marine sites in Saudi Arabia
Authors: Syed S. 
Published: June 2009

AbstractAtmospheric corrosion tests, according to ASTM G50‐76, have been carried out in Saudi Arabia, at eight marine sites representing different environmental conditions. Environmental factors such as average temperature, average relative humidity, and deposition rates of atmospheric pollutants (Cl− and SO2) was investigated. X‐ray diffraction has been used to determine the composition of the corrosion products. Corrosion rates have been determined for each sample at each of the exposure sites via loss of weight. The obtained data were used for the classification of atmospheric aggressivity, according to ISO 9223. The results obeyed well with the empirical kinetics equation of the form C = Ktn, where K and C are the corrosion losses in mg/cm2 after 1 and t years of the exposure respectively, and n is constant. Based on n values, the corrosion mechanism of carbon steel is predicted. The major constituent of the rust formed in marine environment is goethite (α‐FeOOH). Samples also show the presence of a large proportion of lepidocrocite (γ‐FeOOH) and small amounts of ferrihydrite and maghemite (α‐Fe203).
Efficient Grafting of Hyperbranched Polyglycerol from Hydroxyl‐Functionalized Multiwalled Carbon Nanotubes by Surface‐Initiated Anionic Ring‐Opening Polymerization
Authors: Zhou Li , Gao Chao , Xu Weijian 
Published: June 2009

AbstractBiocompatible hyperbranched polyglycerol (HPG) has been covalently grafted from the surfaces of multiwalled carbon nanotubes (MWNTs) by the “grafting from” method based on in situ anionic ring‐opening polymerization. The macroinitiator of hydroxyl‐functionalized MWNTs (MWNT‐OH) with hydroxyl density of 1.39 mmol per gram of nanotubes was prepared by one‐pot nitrene chemistry in N‐methyl‐2‐pyrrolidone (NMP) at 160 °C for 12 h. The amount of HPG grafted from MWNTs can be readily adjusted in a wide range up to 90.8wt.‐% by tuning the feed ratio of glycidol to MWNT‐OH. The resulting HPG‐grafted MWNTs (MWNT‐g‐HPG) nanohybrids were characterized by TGA, FT‐IR, and NMR spectroscopy, HRTEM, and SEM. The as‐prepared nanohybrids show good dispersibility in polar solvents such as water, DMF, DMSO, and methanol. On the basis of numerous functional hydroxyl groups of the HPG grown on MWNTs, fluorescent molecules of rhodamine 6B were conjugated to the surface of MWNT‐g‐HPG by N, N′‐dicyclohexylcarbodiimide (DCC) coupling, affording fluorescent MWNTs. The multifunctional MWNT‐g‐HPG nanohybrids promise potential applications in drug delivery, cell imaging and bioprobing.magnified image
Muscle biopsy substantiates long‐term MRI alterations one year after a single dose of botulinum toxin injected into the lateral gastrocnemius muscle of healthy volunteers
Authors: Schroeder A. Sebastian , Ertl‐Wagner Birgit , Britsch Stefanie , Schröder J. Michael , Nikolin Stefan , Weis Joachim , Müller‐Felber Wolfgang , Koerte Inga , Stehr Maximilian , Berweck Steffen , Borggraefe Ingo , Heinen Florian 
Published: June 2009

AbstractDespite numerous clinical and experimental studies on botulinum toxin type A (BoNT/A), long‐term alterations of muscle texture and fine structure following BoNT/A treatment have thus far not been studied in normal human skeletal muscle. After obtaining institutional review board approval, we performed a prospective, placebo‐controlled, double‐blinded follow‐up study on two healthy adults using magnetic resonance imaging (MRI) and muscle biopsy to visualize long‐term alterations after a single BoNT/A injection into the lateral head of the gastrocnemius muscle. MRI disclosed a high‐signal‐intensity pattern in short tau inversion recovery sequences, and a reduction of the cross‐sectional area in the BoNT/A‐injected, but not in the saline‐injected contralateral control muscle (at 6 to 9 months in volunteer A: 73%, in B: 62%; at 12 months in A: 88%, and in B: 78%). Enzyme histochemistry, 12 months after injection, confirmed neurogenic atrophy of muscle fibers only in the BoNT/A‐injected muscle. Electron microscopy revealed additional degenerative changes at the neuromuscular junction. The data confirm that MRI is a suitable tool to monitor the long‐term effect of BoNT/A on skeletal muscle. Neurogenic muscle atrophy following a single BoNT/A injection should be taken into consideration when repeated BoNT/A injections into the same muscles are proposed. © 2009 Movement Disorder Society
Tremor on smiling
Authors: Schwingenschuh Petra , Cordivari Carla , Czerny Julia , Esposito Marcello , Bhatia Kailash P. 
Published: June 2009

AbstractFacial tremor occurring on smiling is a rare phenomenon and has been described (to the best of our knowledge) in the literature only once. We describe two patients who presented with a bilateral facial tremor that occurred only on smiling and other activation of therisorii muscles and had a high frequency of 9 Hz. One patient additionally suffered from young‐onset Parkinson's disease, whereas the other had no further neurological symptoms or signs apart from this tremor. Anti‐parkinsonian medication was unhelpful for the facial tremor in the patient with Parkinson's disease. Tremor on smiling may be a discrete entity or may be associated in some cases of Parkinson's disease. © 2009 Movement Disorder Society
Quantification of pulmonary blood flow (PBF): Validation of perfusion MRI and nonlinear contrast agent (CA) dose correction with HO positron emission tomography (PET)
Authors: Neeb Daniel , Kunz Rainer Peter , Ley Sebastian , Szábo Gábor , Strauss Ludwig G. , Kauczor Hans‐Ulrich , Kreitner Karl‐Friedrich , Schreiber Laura Maria 
Published: June 2009

AbstractValidation of quantification of pulmonary blood flow (PBF) with dynamic, contrast‐enhanced MRI is still missing. A possible reason certainly lies in difficulties based on the nonlinear dependence of signal intensity (SI) from contrast agent (CA) concentration. Both aspects were addressed in this study. Nine healthy pigs were examined by first‐pass perfusion MRI using gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) and HO positron emission tomography (PET) imaging. Calculations of hemodynamic parameters were based on a one‐compartment model (MR) and a two‐compartment model (PET). Simulations showed a significant error when assuming a linear relation between MR SI and CA dose in the arterial input function (AIF), even at low doses of 0.025 mmol/kg body weight (BW). To correct for nonlinearity, a calibration curve was calculated on the basis of the signal equation. The required accuracy of equation parameters (like longitudinal relaxation time) was evaluated. Error analysis estimates <5% over‐/underestimation of the corrected SI. Comparison of PET and MR flow values yielded a significant correlation (P < 0.001) in dorsal regions where signal‐to‐noise ratio (SNR) was sufficient. Changes in PBF due to the correction method were significant (P < 0.001) and resulted in a better agreement: mean values (standard deviation) in units of ml/min/100 ml lung tissue were 59 (15) for PET, 112 (28) for uncorrected MRI, and 80 (21) for corrected MRI. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
A simulation environment for diffusion weighted MR experiments in complex media
Authors: Balls Gregory T. , Frank Lawrence R. 
Published: June 2009

AbstractSimulations of diffusion in neural tissues have traditionally been limited to analytical solutions, to grid‐based solvers, or to small‐scale Monte Carlo simulations. None of these approaches has had the capability to simulate realistic complex neural tissues on the scale of even a single voxel of reasonable (i.e., clinical) size. An approach is described that combines a Monte Carlo Brownian dynamics simulator capable of simulating diffusion in arbitrarily complex polygonal geometries with a signal integrator flexible enough to handle a variety of pulse sequences. Taken together, this package provides a complete and general simulation environment for diffusion MRI experiments. The simulator is validated against analytical solutions for unbounded diffusion and diffusion between parallel plates. Further results are shown for aligned fibers, varying packing density and permeability, and for crossing straight fibers. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Quantifying endogenous glucose production and contributing source fluxes from a single 2H NMR spectrum
Authors: Nunes Patricia M. , Jones John G. 
Published: June 2009

AbstractEndogenous glucose production (EGP), gluconeogenic and glycogenolytic fluxes by analysis of a single 2H‐NMR spectrum is demonstrated with 6‐hr and 24‐hr fasted rats. Animals were administered [1‐2H, 1‐13C]glucose, a novel tracer of glucose turnover, and 2H2O. Plasma glucose enrichment from both tracers was quantified by 2H‐NMR analysis of monoacetone glucose. The 6‐hr fasted group (n = 7) had EGP rates of 95.6 ± 13.3 μmol/kg/min, where 56.2 ± 7.9 μmol/kg/min were derived from PEP; 12.1 ± 2.1 μmol/kg/min from glycerol, and 32.1 ± 4.9 μmol/kg/min from glycogen. The 24‐hr fasted group (n = 7) had significantly lower EGP rates (52.8 ± 7.2 μmol/kg/min, P = 0.004 vs. 6 hr) mediated by a significantly reduced contribution from glycogen (4.7 ± 5.9 μmol/kg/min, P = 0.02 vs. 6 hr) while PEP and glycerol contributions were not significantly different (39.5 ± 3.9 and 8.5 ± 1.2 μmol/kg/min, respectively). These estimates agree with previous assays of EGP fluxes in fasted rats obtained by multinuclear NMR analyses of plasma glucose enrichment from 2H2O and 13C‐glucose tracers. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.
Rapid 3D radiofrequency field mapping using catalyzed double‐angle method
Authors: Wang Dingxin , Zuehlsdorff Sven , Larson Andrew C. 
Published: June 2009

AbstractA new method is presented for rapid and accurate large volumetric radiofrequency (RF) field (B) mapping. This method is a modification of the double‐angle method (DAM), which accelerates imaging speed and applies 3D acquisition to improve B measurement accuracy. It reduces repetition time and scan time by introducing a catalyzation RF pulse chain at the end of each DAM repetition cycle. The catalyzation pulse chain ensures that, after each TR period, the longitudinal magnetizations reach the same state for both measurements at two flip angles for the DAM so that the long TR requirement (TR ≥ 5 T1) for complete relaxation of longitudinal magnetization of DAM becomes unnecessary. A multi‐echo imaging sequence is additionally incorporated to further improve the efficiency of data acquisition. Simulations demonstrate an excellent flip angle measurement accuracy for catalyzed DAM even with TR << T1. Phantom and in vivo volunteer studies are presented to demonstrate the catalyzation effect upon B mapping and the application of 3D catalyzed DAM for rapid and accurate large volume RF field mapping. Copyright © 2009 John Wiley & Sons, Ltd.