bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mechanism of DNA depurination by carcinogens in relation to cancer initiation
Authors: Cavalieri Ercole , Saeed Muhammad , Zahid Muhammad , Cassada David , Snow Daniel , Miljkovic Momcilo , Rogan Eleanor 
Published: December 2011

AbstractDepurinating DNA adducts formed by aromatic hydrocarbons and catechol estrogen quinones play a major role in cancer initiation. Most of these adducts depurinate instantaneously, but some guanine adducts depurinate from DNA with half‐lives of hours. We report here, that after 10 h at 37 °C, reaction of estradiol‐3,4‐quinone (E2‐3,4‐Q) with ds‐DNA to yield N7Gua and N3Ade adducts was complete and more efficient than with ss‐DNA. When E2‐3,4‐Q reacted with t‐RNA, no adducts were detected after 10 h, and the level of N3Ade and N7Gua adducts after 10 days was less than half that with ss‐DNA after 10 h. Reaction of E2‐3,4‐Q and dG yielded 4‐OHE2‐1‐N7dG, which spontaneously depurinated to yield 4‐OHE2‐1‐N7Gua. To investigate the mechanism of depurination, E2‐3,4‐Q was reacted with carbocyclicdeoxyguanosine, in which the ring oxygen of the deoxyribose moiety is substituted with CH2, and depurination was observed. The results from this experiment demonstrate that the oxocarbenium ion mechanism plays the major role in depurination and provides the first experimental evidence for this mechanism. A newly discovered β‐elimination mechanism also plays a minor role in depurination. Understanding why the depurinating estrogen‐DNA adducts come from DNA, and not from RNA, underscores the critical role that these adducts play in initiating cancer. © 2011 IUBMB IUBMB Life, 2011.
Pacific coral oxygen isotope and the tropospheric temperature gradient over the Asian monsoon region: a tool to reconstruct past Indian summer monsoon rainfall
Authors: Chakraborty Supriyo , Goswami Bhupendra N. , Dutta Koushik 
Published: December 2011

AbstractHaving recognized that it is the tropospheric temperature (TT) gradient rather than the land–ocean surface temperature gradient that drives the Indian monsoon, a new mechanism of El Niño/Southern Oscillation (ENSO) monsoon teleconnection has been unveiled in which the ENSO influences the Indian monsoon by modifying the TT gradient over the region. Here we show that equatorial Pacific coralline oxygen isotopes reflect TT gradient variability over the Indian monsoon region and are strongly correlated to monsoon precipitation as well as to the length of the rainy season. Using these relationships we have been able to reconstruct past Indian monsoon rainfall variability of the first half of the 20th century in agreement with the instrumental record. Additionally, an older coral oxygen isotope record has been used to reconstruct seasonally resolved summer monsoon rainfall variability of the latter half of the 17th century, indicating that the average annual rainfall during this period was similar to that during the 20th century. Copyright © 2011 John Wiley & Sons, Ltd.
Tropical cyclone activity and western North Atlantic stratification over the last millennium: a comparative review with viable connections
Authors: Woodruff Jonathan D. , Sriver Ryan L. , Lund David C. 
Published: December 2011

AbstractTropical cyclones (TC) are recognized to modify the thermal structure of the upper ocean through the process of vertical mixing. Assessing the role this mixing plays in the overall stratification of the upper ocean is difficult, due to the relatively short and incomplete instrumental record. Proxy records for both TC landfalls and oceanographic stratification are preserved within the geological record and provide insight for how past changes in TC‐induced mixing have potentially affected water column structure prior to the instrumental record. Here we provide the first comparison between previously published paleo‐reconstructions of vertical ocean density and tropical cyclone activity from the western North Atlantic. A prominent lull in TC activity has been observed prior to approximately 1700 CE that extends back several centuries. This interval of low TC activity is shown to be concurrent with the timing of increased ocean stratification near Great Bahama Bank, potentially due in part to reduced TC‐induced mixing. To test whether this relationship is feasible, we present numerical results from a coarse‐resolution ocean general circulation model experiment isolating the effect of TC surface wind forcing on the upper ocean. An anomaly of roughly 0.12 kg m−3 in vertical stratification occurs above and below the mixed layer for model runs with and without TC mixing. This anomaly is roughly 25% of the entire paleo‐density signal observed just prior to 1700 CE. These results suggest that TC mixing alone cannot completely explain the density anomaly observed prior to 1700 CE, but support TC variability as an important contributor to enhancing oceanic stratification during this interval. Copyright © 2011 John Wiley & Sons, Ltd.
An assessment of the utility of regional diatom‐based tidal‐level transfer functions
Authors: Wilson Graham P. , Lamb Angela L. 
Published: December 2011

AbstractIn order to understand natural sea‐level variability, and to enhance future predictions, accurate and precise estimates of Holocene tidal levels are required. Although the application of diatom‐based transfer functions can yield such data, these work best when underpinned by local training sets. Urbanized estuaries offer little prospect of obtaining local training sets and, instead, the reliability of regional transfer functions has to be assessed. The performance of a published regional (UK) diatom‐based tidal‐level transfer function applied to fossil assemblages from two contrasting core sites in the Mersey Estuary, UK, is assessed using modern analogue techniques and sediment isotope data. We find that, although estimated tidal levels coincide with changes in organic matter source, the frequent lack of modern analogues mean that palaeotide estimates are without basis. This is likely a consequence of the site‐specific nature of diatom assemblages in higher intertidal and supratidal areas in particular, where local factors are expected to exert a greater control on their ecology. This situation may be partly resolved by constructing and applying much larger regional training sets from multiple higher intertidal and supratidal sites (where intact). Otherwise the application of alternative techniques, such as regional foraminiferal tidal‐level transfer functions, may be more appropriate. Copyright © 2011 John Wiley & Sons, Ltd.
Selective separation of magnolol using molecularly imprinted membranes
Authors: Zhu Xing‐Yi , Zheng Zhang‐Juan , Xie Jie , Wang Ping 
Published: December 2011

AbstractMolecularly imprinted membranes (MIMs) for selective separation of magnolol were prepared by thermal polymerization using magnolol as the template, ethylene glycol dimethacrylate (EGDMA) as the cross‐linker, 2,2‐azobisisobutyronitrile (AIBN) as the initiator, organic solvent as the porogen, methacrylamide (MAM) and acrylic acid (AA) as the functional monomers and cellulose acetate as the agglutinant. Commercial filter paper was used as the supporting material. The effects of different porogens and the ratio of functional monomers on the binding and recognition capacity of MIMs were investigated, and the morphology of the membranes was examined by scanning electron microscopy (SEM). The results showed that the MIMs have the highest selectivity to magnolol when the ratio of MAM/AA was 1:4 and tetrahydrofuran (THF) with dimethyl sulfoxide (DMSO) was used as the porogen. The morphology of the imprinted membranes after template extracting is much rougher with big cavities than that of the non‐imprinted membranes (NIMs) and the imprinted membranes before template extracting. The MIMs can selectively separate the magnolol.
Perampanel, an AMPA antagonist, found to have no benefit in reducing “off” time in Parkinson's disease
Authors: Lees Andrew , Fahn Stanley , Eggert Karla M. , Jankovic Joseph , Lang Anthony , Micheli Federico , Maral Mouradian M. , Oertel Wolfgang H. , Olanow C. Warren , Poewe Werner , Rascol Olivier , Tolosa Eduardo , Squillacote David , Kumar Dinesh 
Published: December 2011

AbstractBackground:Perampanel is a selective, noncompetitive α‐amino‐3‐hydroxy‐5‐methyl‐4‐isoxazole‐propionic acid receptor antagonist. Two multicenter randomized, double‐blind, placebo‐controlled, parallel‐group phase III studies assessed the efficacy and safety of adjunctive perampanel in patients with Parkinson's disease and motor fluctuations.Methods:In both phase III studies (301 and 302), levodopa‐treated patients were randomized and treated with once‐daily oral placebo (n = 504), perampanel 2 mg (n = 509), or perampanel 4 mg (n = 501). The primary end point was change in daily “off” time from baseline. The treatment period was 30 weeks in study 301 and 20 weeks in study 302.Results:For any efficacy end point, perampanel 2 or 4 mg was not superior to placebo. Perampanel was well tolerated up to 4 mg/day.Conclusions:Perampanel failed to significantly improve motor symptoms versus placebo. There was also no effect on the duration or disability of levodopa‐induced dyskinesia. © 2011 Movement Disorder Society
Clinical validation of movement disorder society–recommended diagnostic criteria for Parkinson's disease with dementia
Authors: Barton Brandon , Grabli David , Bernard Bryan , Czernecki Virginie , Goldman Jennifer G. , Stebbins Glenn , Dubois Bruno , Goetz Christopher G. 
Published: December 2011

AbstractThe objective of this work was to evaluate the Movement Disorders Society (MDS) Task Force–proposed screening checklist for detecting Parkinson's disease dementia (PD‐D) in relation to full neuropsychological testing. An MDS Task Force has proposed diagnostic procedures for PD‐D, which have not been fully validated against more extensive neuropsychological testing. PD subjects were recruited from 2 specialty centers. A neuropsychologist evaluated them for dementia as part of routine clinical care. Independent clinical neurologists administered the MDS PD‐D screening checklist. Diagnosis of PD‐D by the 2 methods was compared. Ninety‐one PD subjects had a mean age of 66.3 (SD = 9.7) years and a mean PD duration of 8.8 (SD = 6.1) years. Seven subjects (7.7%) met all 8 screening checklist criteria from the MDS PD‐D screening tool and were classified as probable PD‐D. Fifteen (16.5%) subjects were classified as PD‐D by full neuropsychological assessment. The screening checklist showed 100% specificity, but only 46.7% sensitivity, for diagnosing PD‐D compared to the full neuropsychological assessment. PD‐D cases missed by the PD‐D screening tool were largely due to 2 checklist items that were not endorsed (absence of depression and Mini‐Mental State Examination [MMSE] scores <26). There was moderate agreement between these 2 methods for determination of PD‐D (kappa = 0.59, P < .001). The MDS‐PD‐D screening checklist is highly accurate for detecting PD‐D if all items are endorsed. However, for cases that do not meet these criteria, full neuropsychological testing is needed to differentiate PD‐D from milder cognitive impairment. Revision of the checklist by altering or eliminating the 2 problematic checklist items may improve sensitivity. © 2011 Movement Disorder Society
The postprandial inflammatory response after ingestion of heated oils in obese persons is reduced by the presence of phenol compounds
Authors: Perez‐Herrera A. , Delgado‐Lista J. , Torres‐Sanchez L. A. , Rangel‐Zuñiga O. A. , Camargo A. , Moreno‐Navarrete J. M. , Garcia‐Olid B. , Quintana‐Navarro G. M. , Alcala‐Diaz J. F. , Muñoz‐Lopez C. , Lopez‐Segura F. , Fernandez‐Real J. M. , Luque de Castro M. D. , Lopez‐Miranda J. , Perez‐Jimenez F. 
Published: December 2011

AbstractScope Heating during the process of cooking alters the chemical properties of foods and may affect subsequent postprandial inflammation. We tested the effects of four meals rich in different oils subjected to heating on the postprandial inflammatory metabolism of peripheral blood mononuclear cells (PBMCs).Methods and results Twenty obese participants received four breakfasts following a randomized crossover design, consisting of milk and muffins made with different oils (virgin olive oil (VOO), sunflower oil (SFO), and a mixture of seeds oil (SFO/canola oil) with added either dimethylpolysiloxane (SOD), or natural antioxidants from olive mill wastewater alperujo (phenols; SOP)), previously subjected to 20 heating cycles. Postprandial inflammatory status in PBMCs was assessed by the activation of nuclear NF‐κB, the concentration in cytoplasm of the NF‐κB inhibitor (IκB‐α), the mRNA levels of NF‐κB subunits and activators (p65, IKKβ, and IKKα) and other inflammatory molecules (TNF‐α, IL‐1β, IL‐6, MIF, and JNK), and lipopolysaccharide (LPS) levels. VOO and SOP breakfasts reduced NF‐κB activation, increased IκB‐α, and decreased LPS plasma concentration. SFO increased IKKα, IKKβ, p65, IL‐1b, IL‐6, MIF, and JNK mRNA levels, and plasma LPSConclusion Oils rich in phenols, whether natural (VOO) or artificially added (SOP), reduce postprandial inflammation, compared with seed oil (sunflower).
A Kinetic Model for Non‐Oxidative Thermal Degradation of Nylon 66
Authors: Karimi Hadiseh , Schaffer Mark A. , McAuley Kim B. 
Published: December 2011

AbstractA model is developed to predict rates of undesirable reactions in the low‐moisture, high‐temperature finishing stage of nylon 66 production. The model contains 56 unknown parameters and initial conditions, which are ranked based on their influence on model predictions, correlation with other parameters and uncertainty in their initial guesses. A mean‐square‐error criterion is used to determine that 43 of 56 parameters should be estimated. The proposed model, which describes the effect of melt‐phase water concentration on degradation, matches the data well with typical errors of 6.1 and 2.9%, respectively, for amine ends (A) and carboxyl ends (C) and 4.3, 27.2, and 29.4%, respectively, for evolution rates of CO2, NH3, and cyclopentanone (CPK).magnified image
Shared velocity encoding: A method to improve the temporal resolution of phase‐contrast velocity measurements
Authors: Lin Hung‐Yu , Bender Jacob A. , Ding Yu , Chung Yiu‐Cho , Hinton Alice M. , Pennell Michael L. , Whitehead Kevin K. , Raman Subha V. , Simonetti Orlando P. 
Published: December 2011

AbstractPhase‐contrast magnetic resonance imaging (PC‐MRI) is used routinely to measure fluid and tissue velocity with a variety of clinical applications. Phase‐contrast magnetic resonance imaging methods require acquisition of additional data to enable phase difference reconstruction, making real‐time imaging problematic. Shared Velocity Encoding (SVE), a method devised to improve the effective temporal resolution of phase‐contrast magnetic resonance imaging, was implemented in a real‐time pulse sequence with segmented echo planar readout. The effect of SVE on peak velocity measurement was investigated in computer simulation, and peak velocities and total flow were measured in a flow phantom and in volunteers and compared with a conventional ECG‐triggered, segmented k‐space phase‐contrast sequence as a reference standard. Computer simulation showed a 36% reduction in peak velocity error from 8.8 to 5.6% with SVE. A similar reduction of 40% in peak velocity error was shown in a pulsatile flow phantom. In the phantom and volunteers, volume flow did not differ significantly when measured with or without SVE. Peak velocity measurements made in the volunteers using SVE showed a higher concordance correlation (0.96) with the reference standard than non‐SVE (0.87). The improvement in effective temporal resolution with SVE reconstruction has a positive impact on the precision and accuracy of real‐time phase‐contrast magnetic resonance imaging peak velocity measurements. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.
Preserving the accuracy and resolution of the sodium bioscale from quantitative sodium MRI during intrasubject alignment across longitudinal studies
Authors: Atkinson Ian C. , Lu Aiming , Thulborn Keith R. 
Published: December 2011

AbstractEmerging applications of sodium bioscales derived from quantitative sodium magnetic resonance imaging assess temporal changes in regional sodium concentration over intervals that vary from hours (monitoring tissue viability in stroke) to weeks (monitoring brain tumor treatment during radiation therapy) or even years (monitoring progression of neurodegenerative disease). Accurate interpretation of such quantitative data requires precise registration between magnetic resonance imaging sessions to avoid session‐to‐session changes in partial volume effects between normal tissue (∼38 mM sodium concentration), lesions (variable sodium concentration), and cerebrospinal fluid (∼144 mM sodium concentration). The existing Automated Image Registration algorithm is shown to be suitable for rapid, accurate, and precise determination of the transform that aligns sodium magnetic resonance images. Implementation of this transform during image reconstruction from thek‐space data is shown to produce smaller errors than conventional image‐domain interpolation. Experimental results at 9.4 T and 3.0 T demonstrating this registration approach to sodium data illustrate preservation of quantification accuracy during alignment of sodium magnetic resonance images acquired from the same subject during different imaging sessions. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Biexponential diffusion decay in formalin‐fixed prostate tissue: Preliminary findings
Authors: Bourne Roger M. , Kurniawan Nyoman , Cowin Gary , Stait‐Gardner Timothy , Sved Paul , Watson Geoffrey , Chowdhury Supriya , Price William S. 
Published: December 2011

AbstractMagnetic resonance microimaging was used to measure diffusion decay over an extended b‐factor range in a formalin‐fixed normal prostate sample and a Gleason pattern 3+4 cancer tissue sample. The coefficients of biexponential fits to diffusion decay data from 1600 voxels of dimension 160 × 160 × 160 μm3 in each sample were correlated with underlying epithelial and stromal compartment partial volumes estimated from high‐resolution apparent diffusion coefficient (ADC) data (40 × 40 × 40 μm3 voxels) from the same tissue. In the normal tissue sample, the signal fractions of the low and high ADC components of the biexponential fits correlated linearly with partial volumes of epithelial tissue (R2 = 0.6) and stromal tissue (R2 = 0.5), respectively. Similar but weaker correlations were observed in the cancer sample. Epithelium‐containing high spatial resolution voxels appeared to be composed of ∼60% low ADC and ∼40% high ADC component. Stromal voxels appeared to be composed of ∼20% low ADC and ∼80% high ADC component. This preliminary report suggests that distinctly different diffusion properties in microscopically adjacent cell types contribute to the multiexponential diffusion decay phenomenon in prostate tissue. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Somatotopic arrangement of thermal sensory regions in the healthy human spinal cord determined by means of spinal cord functional MRI
Authors: Stroman Patrick W. , Bosma Rachael L. , Tsyben Anastasia 
Published: December 2011

AbstractPrevious functional MRI studies of normal sensory function in the human spinal cord, including right‐to‐left symmetry of activity, have been influenced by order effects between repeated studies. In this study, we apply thermal sensory stimulation to four dermatomes within each functional MRI time‐series acquisition. Each of the four dermatomes receives a unique stimulation paradigm, such that the four paradigms form a linearly independent set, enabling detection of each individual stimulus response. Functional MRI data are shown spanning the cervical spinal cord and brainstem in 10 healthy volunteers. Results of general linear model analysis demonstrate consistent patterns of activity within the spinal cord segments corresponding to each dermatome, and a high degree of symmetry between right‐side and left‐side stimulation. Connectivity analyses also demonstrate consistent areas of activity and connectivity between spinal cord and brainstem regions corresponding to known anatomy. However, right‐side and left‐side responses are not at precisely the same rostral–caudal positions, but are offset by several millimeters, with left‐side responses consistently more caudal than right‐side responses. The results confirm that distinct responses to multiple interleaved sensory stimuli can be distinguished, enabling studies of sensory responses within the spinal cord without the confounding effects of comparing sequential studies. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Prospective self‐gating for swallowing motion: A feasibility study in carotid artery wall MRI using three‐dimensional variable‐flip‐angle turbo spin‐echo
Authors: Fan Zhaoyang , Zuehlsdorff Sven , Liu Xin , Li Debiao 
Published: December 2011

AbstractThree‐dimensional black‐blood MRI is a promising noninvasive imaging technique for the assessment of atherosclerotic carotid artery disease. However, this technique is inherently susceptible to motion. In particular, swallowing can result in considerable wall motion at the carotid bifurcations, which may induce drastic image degradation or substantial overestimation of wall thickness. Self‐gating techniques have previously been shown to be capable of resolving and compensating for cardiac or respiratory motion during MRI. This work presents a self‐gating‐based prospective motion gating scheme that is combined with a three‐dimensional variable‐flip‐angle turbo spin‐echo sequence (SPACE) for detecting swallowing motion. Self‐gating signal readouts along the superior–inferior direction during each repetition time period are used to derive the projection profiles of the imaging volume. Based on cross‐correlation analysis between the projection profiles and the corresponding reference profiles, swallowing motion can be detected and the motion‐contaminated data will subsequently be discarded and reacquired in the next repetition time. The self‐gated SPACE sequence was validated on eight healthy volunteers and two patients and, when compared with the conventional SPACE sequence, proved to be more resistant to swallowing motion and significantly improved image quality as well as the sharpness of carotid artery wall boundaries. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.
Influence of dense‐array EEG cap on fMRI signal
Authors: Luo Qingfei , Glover Gary H. 
Published: December 2011

AbstractDense‐array (>64 channel) electroencephalography (EEG) systems are increasingly being used in simultaneous EEG–functional magnetic resonance imaging (fMRI) studies. However, with increasing channel count, dense‐array EEG caps can induce more severe signal dropout in the MRI images than conventional systems due to the radiofrequency shielding effect of the denser wire bundle. This study investigates the influence of a 256‐channel EEG cap on MRI image quality and detection sensitivity of blood oxygen level dependent fMRI signal. A theoretical model is first established to describe the impact of the EEG cap on anatomic signal, noise, signal‐to‐noise ratio, and contrast‐to‐noise ratio of blood oxygen level dependent signal. Seven subjects were scanned to measure and compare the T2*‐weighted image quality and fMRI detection sensitivity with and without the EEG cap using an auditory/visual/sensorimotor task. The results show that the dense‐array EEG cap can substantially reduce the anatomic signal in the brain areas (visual cortex) near the conducting wires (average percent decrease ≈ 38%). However, the image signal‐to‐noise ratio with and without the EEG cap was comparable (percent decrease < 8%, not statistically significant), and there was no statistically significant difference in the extent of blood oxygen level dependent activation. This suggests that the ability to detect fMRI signal is nearly unaffected by dense‐array EEG caps in simultaneous EEG–fMRI experiments. Magn Reson Med, 2012. © 2011 Wiley Periodicals, Inc.