bluuebunny/crossref_metadata_2025_split huggingface dataset:
Incorporating contrast agent diffusion into the analysis of DCE‐MRI data
Authors: Pellerin Martin , Yankeelov Thomas E. , Lepage Martin 
Published: October 2007

AbstractStandard two‐compartment pharmacokinetic models that describe the dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) time course of gadolinium diethylenetriamine pentaacetic acid (Gd‐DTPA) concentration in a tissue do not account for the passive diffusion of contrast agent (CA) from a well‐perfused to a less vascularized region. Even when the arterial input function (AIF) is perfectly known, the standard Tofts model returns inaccurate values of Ktrans (mean absolute relative difference [ARD] of 43%) from realistic simulated data where a well‐defined delineation exists between a well‐perfused and a poorly vascularized region. This contribution proposes a diffusion‐perfusion (DP) model in which diffusion of a low molecular weight CA is incorporated in the standard two‐compartment Tofts model. The proposed DP model reliably retrieved the values of Ktrans and ve (mean ARD of 16% and 17%, respectively) from simulated data. On mouse adenocarcinoma xenograft data showing evidence of CA diffusion, the standard model returned unphysical values of ve in the tumor core whereas the proposed DP model found values that were in the physical range (0 < ve < 1) throughout the tissue. In addition, Ktrans distributions from the DP model more closely corresponded to the observed sharp delineation between highly and poorly perfused areas observed in the mouse tumors. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
A theoretical and experimental investigation of the tagging efficiency of pseudocontinuous arterial spin labeling
Authors: Wu Wen‐Chau , Fernández‐Seara María , Detre John A. , Wehrli Felix W. , Wang Jiongjiong 
Published: October 2007

AbstractArterial spin labeling (ASL) is capable of noninvasively measuring blood flow by magnetically tagging the protons in arterial blood, which has been conventionally achieved using instantaneous (PASL) or continuous (CASL) RF pulses. As an intermediate method, pseudocontinuous ASL (pCASL) utilizes a train of discrete RF pulses to mimic continuous tagging that is often unavailable on imagers due to the requirement of continuous RF transmit capabilities. In the present study, we implemented two versions of pCASL (balanced and unbalanced gradient waveforms in tag and control scans) for both transmit/receive coils and array receivers. Experimental data show a 50% ± 4% increase of signal‐to‐noise ratio (SNR) compared with PASL and a higher tagging efficiency than amplitude‐modulated (AM) CASL (80% vs. 68%). Computer simulations predict an optimal tagging efficiency of 85% for flow velocities from 10 to 60 cm/s. It is theoretically and experimentally demonstrated that the tagging efficiency of pCASL is dependent upon the resonance offset and flip angle of the RF pulse train. We conclude that pCASL has the potential of combining the merits of PASL, including less hardware demand and higher tagging efficiency, and CASL, which includes a longer tagging bolus and thus higher SNR. These improvements provide a better balance between tagging efficiency and SNR. Magn Reson Med 58:1020–1027, 2007. © 2007 Wiley‐Liss, Inc.
Radiofrequency heating at 9.4T: In vivo temperature measurement results in swine
Authors: Shrivastava Devashish , Hanson Timothy , Schlentz Robert , Gallaghar William , Snyder Carl , DelaBarre Lance , Prakash Surya , Iaizzo Paul , Vaughan J. Thomas 
Published: October 2007

AbstractIn vivo temperatures were correlated to the whole head average specific absorption rate (SARavg) at 9.4T using 12 anesthetized swine (mean animal weight = 52 kg, standard deviation = 6.7 kg). Correlating the temperatures and SARavg is necessary to ensure safe levels of human heating during ultra‐high field MR exams. The temperatures were measured at three depths inside the brain, in the rectum, and at the head‐skin of swine. A 400 MHz, continuous wave RF power was deposited to the head using a volume coil. The SARavg values were varied between 2.7–5.8 W/kg. The RF power exposure durations were varied between 1.4–3.7 hr. To differentiate the temperature response caused by the RF from that of the anesthesia, the temperatures were recorded in four unheated swine. To study the effect of the spatial distribution of the RF and tissue properties, the temperature probes were placed at two brain locations (n = 4 swine for each location). Results showed that the in vivo brain temperatures correlated to the SARavg in a geometry‐dependent manner. Additionally, 1) the skin temperature change was not the maximum temperature change; 2) the RF heating caused an inhomogeneous brain temperature distribution; and 3) the maximum temperature occurred inside the brain. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Accelerated short‐TE 3D proton echo‐planar spectroscopic imaging using 2D‐SENSE with a 32‐channel array coil
Authors: Otazo Ricardo , Tsai Shang‐Yueh , Lin Fa‐Hsuan , Posse Stefan 
Published: October 2007

AbstractMR spectroscopic imaging (MRSI) with whole brain coverage in clinically feasible acquisition times still remains a major challenge. A combination of MRSI with parallel imaging has shown promise to reduce the long encoding times and 2D acceleration with a large array coil is expected to provide high acceleration capability. In this work a very high‐speed method for 3D‐MRSI based on the combination of proton echo planar spectroscopic imaging (PEPSI) with regularized 2D‐SENSE reconstruction is developed. Regularization was performed by constraining the singular value decomposition of the encoding matrix to reduce the effect of low‐value and overlapped coil sensitivities. The effects of spectral heterogeneity and discontinuities in coil sensitivity across the spectroscopic voxels were minimized by unaliasing the point spread function. As a result the contamination from extracranial lipids was reduced 1.6‐fold on average compared to standard SENSE. We show that the acquisition of short‐TE (15 ms) 3D‐PEPSI at 3 T with a 32 × 32 × 8 spatial matrix using a 32‐channel array coil can be accelerated 8‐fold (R = 4 × 2) along y‐z to achieve a minimum acquisition time of 1 min. Maps of the concentrations of N‐acetyl‐aspartate, creatine, choline, and glutamate were obtained with moderate reduction in spatial‐spectral quality. The short acquisition time makes the method suitable for volumetric metabolite mapping in clinical studies. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
MRI of regular‐shaped cell‐encapsulating polyhedral microcontainers
Authors: Gimi Barjor , Artemov Dmitri , Leong Timothy , Gracias David H. , Bhujwalla Zaver M. 
Published: October 2007

AbstractWe devised cubic and pyramidal microcontainers for cell encapsulation. While the cube is easier to manipulate, the pyramid offers a higher surface area‐to‐volume ratio and may therefore provide the encapsulated cells with increased access to nutrients. To discern the microcontainers' implant location and environment, and to aid in image‐guided therapy, we showed noninvasive detection of microcontainers using MRI. Diamagnetic microcontainers were imaged using the radio frequency (RF) shielding effect, with negative contrast localized to the interior of the microcontainers. For applications in which it is difficult to distinguish the microcontainers from other hypointensities, positive contrast can be used to discern them. We showed positive‐contrast MRI of a diamagnetic microcontainer. To image microcontainers that are smaller than the spatial resolution of MRI, we performed in vivo negative‐contrast MRI of a ferromagnetic microcontainer. As opposed to the diamagnetic microcontainer, the ferromagnetic microcontainer created a region of MRI contrast several times larger than the microcontainer's dimensions. Magn Reson Med, 2007. © 2007 Wiley‐Liss, Inc.
Forecasting vertical ground surface movement from shrinking/swelling soils with artificial neural networks
Authors: Doris Jeffrey J. , Rizzo Donna M. , Dewoolkar Mandar M. 
Published: October 2007

AbstractArtificial neural networks (ANNs) are used to estimate vertical ground surface movement when soils expand and contract due to changes in soil moisture content caused by changing climate conditions. Several counterpropagation ANN test cases were investigated to map climate data (i.e. temperature and rainfall) to vertical ground surface movement at field sites in Texas and Australia. Three of the four ANN test cases use a historical time series of climate data to forecast ground surface elevation relative to a specified datum. The fourth ANN test case predicts the rate of ground surface movement, and requires post‐processing of the predicted rates to calculate ground surface elevation relative to a specified datum. The counterpropagation network has demonstrated a successful mapping of temperature and rainfall data to vertical ground surface movement at a field site when it is trained with a subset of data from the same field site (test cases 1 and 2). The results of training an ANN on one field site and testing it on another field site (test cases 3 and 4) demonstrate the ability of the ANN to capture trends in vertical ground surface movement. When compared with the predictions from a physics‐based method (shrink test‐water content method) that requires measurements/estimates of changes in soil water content, the ANN‐based predictions (based on climatic changes) captured the trends in the field measurements of shrinking–swelling soil surface movements equally well. These findings are promising and merit further investigation with data from additional field sites. Copyright © 2007 John Wiley & Sons, Ltd.
Ionic liquids as catalytic additives for the acceleration of the photopolymerization of poly(ethylene glycol dimethacrylate)s
Authors: Chesnokov Sergey A , Zakharina Marya Yu , Shaplov Alexander S , Chechet Yuriy V , Lozinskaya Elena I , Mel'nik Olga A , Vygodskii Yakov S , Abakumov Gleb A 
Published: October 2007

AbstractBACKGROUND: The fast development of practical applications of photopolymerizable compositions (PPCs) leads to a growing demand for the elaboration of novel monomers and simultaneously for the investigation of three‐dimensional polymerization mechanisms including the possible influence of initiator, additives, etc. The aim of the current study is to explore and clarify the role of ionic liquids (ILs) as environmentally friendly catalytic additives in the photopolymerization of poly(ethylene glycol dimethacrylate)s.RESULTS: The photopolymerization of triethylene glycol dimethacrylate (TEGDM) and poly(ethylene glycol‐400 dimethacrylate) (PEGDM) in the presence of various ILs both imidazolium‐based, i.e. [1‐methyl‐3‐alkylim]+ (CF3SO2)2N− (im = imidazolium; alkyl = C2H5, C4H9, C14H29), and phosphonium‐based, i.e. [P+ (C6H13)3(C14H29)]X− (X− = PF6−, BF4−, (CF3SO2)2N−, Cl−), as catalytic additives was investigated. The influence of the concentration of the ionic salts as well as the nature of the ILs upon the photopolymerization was studied in detail. It was found that imidazolium ILs accelerate TEGDM photopolymerization and suppress the polymerization of PEGDM. In contrast, polymerization of PEGDM with extra small amounts of phosphonium ionic solvents proceeded at a high rate and offered access to new polymers and the utilization of low‐reactivity monomers in PPCs.CONCLUSION: The most striking advantage is that the use of certain ILs permits the control of polymerization rate to achieve maximum oligomer conversion. Copyright © 2007 Society of Chemical Industry
Learning the drug target‐likeness of a protein
Authors: Xu Huan , Xu HangYang , Lin MingZhi , Wang Wei , Li ZiMu , Huang JiaJu , Chen YuZong , Chen Xin 
Published: October 2007

AbstractCurrent drug discovery and development approaches rely extensively on the identification and validation of appropriate targets; for example, those with marketable and robust therapeutics. Wide‐ranging efforts have been directed at this problem and various approaches have been developed to identify disease‐associated genes as candidates. In this work, we show with statistical significance that successful drug targets, in addition to their linkage to disease, share common characteristics that are disease‐independent. For example, marked differences in functional category, tissue specificity, and sequence variability are observed between known targets and average proteins. These results lead to an interesting hypothesis: potentially good drug targets shall have some desired properties, which we refer to as “drug target‐likeness” that are beyond their disease‐associations. Because of the limited availability of comprehensive protein characteristics data, we tried to learn the drug target‐likeness property at the sequence level. Results show that a support vector machine model is able to accurately distinguish targets from nontargets entirely with sequence features. It is our hope that these encouraging results will invite future systematic proteomic scale experiments to gather necessary protein characteristics data for the accurate and predictive definition of “drug target‐likeness”, providing a new perspective toward understanding and pursuing effective therapeutics.
Proteomic analysis of proteins from bronchoalveolar lavage fluid reveals the action mechanism of ultrafine carbon black‐induced lung injury in mice
Authors: Chang Chih‐Ching , Chen Shu‐Hui , Ho Shih‐Hsin , Yang Chun‐Yuh , Wang Hong‐Da , Tsai Mei‐Ling 
Published: October 2007

AbstractPrevious studies have shown that ultrafine carbon black (ufCB) could cause oxidative stress and lung injury, but the mechanisms have not been clearly demonstrated. In this study, 1‐D gel electrophoresis coupled with LC/MS/MS (1‐D geLC/MS/MS) was carried out with bronchoalveolar lavage fluid (BALF) to identify proteins associated with ufCB‐induced lung injury. If required, Western blot was conducted additionally to validate proteins. Thirty‐three proteins were identified, including leukemia inhibitory factor receptor (LIFR) and epidermal growth factor receptor (EGFR). Western blot analysis showed that ufCB exposure caused the increases of LIFR and EGFR in BALF and decreases of both receptors in lung tissues, suggesting the acceleration of epithelial shedding from the lung and increase of cell debris with membrane proteins EGFR and LIFR in BALF. There were strong correlations between vascular endothelial growth factor (VEGF) and albumin (p<0.01) or α2‐macroglobulin (α2M) in BALF (p<0.05). Importantly, antioxidant ceruloplasmin (Cp) was shown to be produced from lung epithelial cells in response to ufCB exposure. This is the first study to apply 1‐D ge LC/MS/MS and experimental studies to reveal the mechanisms involved in the pathogenesis of ufCB‐induced lung injury.
Atopic characteristics of wheezing children and responses to prednisolone
Authors: Jartti Tuomas , Lehtinen Pasi , Vanto Timo , Vuorinen Tytti , Hiekkanen Heikki , Hartiala Jaakko , Mäkelä Mika J , Ruuskanen Olli 
Published: October 2007

AbstractWe wanted to test the hypothesis that the efficacy of systemic corticosteroid is associated with atopic characteristics in wheezing children.A randomized controlled trial comparing oral prednisolone (2 mg/kg/day in 3 divided doses for 3 days) with placebo in hospitalized wheezing children (n = 266, median 1.6 years, range 3 months to 15.2 years) was conducted. In this post‐hoc analysis, we assessed the link between the efficacy of prednisolone and several atopic characteristics, such as atopy, aeroallergen sensitization, total IgE level, number of sensitizations, eczema, atopic eczema, blood or nasal eosinophils, exhaled nitric oxide, positive modified asthma predictive index/asthma, inhaled corticosteroid medication and parental asthma/allergy. Virology was studied comprehensively. Our primary endpoint was the time until ready for discharge, and the most important secondary endpoint was the occurrence of relapses during the following 2 months. For statistics, we used interaction analyses in uni‐ and multivariate regression models.Overall, prednisolone did not decrease any of our predefined clinical endpoints. Neither was the efficacy of prednisolone associated with atopy. However, prednisolone significantly decreased the time until ready for discharge in children with positive modified asthma predictive index/asthma, inhaled corticosteroids, or rhinovirus infection and/or in children without azithromycin treatment. Prednisolone significantly decreased relapses in children with eczema, nasal eosinophilia and rhinovirus infection.The multiple clinical, inflammatory and viral markers associating with the efficacy of prednisolone should be confirmed in prospective trials. It is important that corticosteroid intervention trials have strict design for these potentially confounding factors. Pediatr Pulmonol. 2007; 42:1125–1133. © 2007 Wiley‐Liss, Inc.
Spirometry in 5‐year‐olds—validation of current guidelines and the relation with asthma
Authors: Turner Stephen W. , Craig Leone C.A. , Harbour Paul J. , Forbes Sarah H. , McNeill Geraldine , Seaton Anthony , Devereux Graham , Helms Peter J. 
Published: October 2007

AbstractIntroduction. Spirometry is more frequently measured in younger children. Our primary aim was to validate 2005 ATS‐ERS Task Force standards for spirometry in adults and older children among a population of 5‐year‐old children. Our secondary aim was to relate spirometry to asthma symptoms.MethodsChildren were participants in a longitudinal cohort study where asthma symptoms and spirometry were assessed.ResultsOf the 827 children assessed, spirometry was obtained in 638 (85 with wheeze). A back‐extrapolated volume/FVC ratio of <5% was achieved in 99% of children, the best two FVC were ≤150 ml of each other in 89% and three efforts were obtained within six attempts in 88%. The best two FVC were within 10% of each other in 82% of children. Only 13% achieved a forced expiratory time (FET) of ≥3 sec, whereas 80% had an FET of ≥1 sec. All criteria (including FET ≥1 s and FVC ≤10%) were met in 400 (65%) of the 638 children. Most spirometric indices were reduced in association with current wheeze and a history of asthma; children with current wheeze had a mean reduction of 0.65 FEV1 z score compared to healthy children, P < 0.001. An FEV1 z score of −1.0 had 82% sensitivity but only 50% specificity for current wheeze, the corresponding numbers for an FEF50 z score of −1.0 being 79% and 71%.ConclusionsThe standards for spirometry are mostly achieved in this age group but are not necessarily valid and require revision. Reliable spirometry is feasible in 5‐year‐old children where reduced measurements are associated with asthma symptoms and in whom FEF50 appears to be the most discriminatory variable. Pediatr Pulmonol. 2007; 42:1144–1151. © 2007 Wiley‐Liss, Inc.
Longitudinal monitoring of pediatric cystic fibrosis lung disease using nitrite in exhaled breath condensate
Authors: Horak F. , Moeller A. , Singer F. , Straub D. , Höller B. , Helbich T.H. , Schneider B. , Eichler I. , Wildhaber J.H. , Hall G.L. 
Published: October 2007

AbstractCystic fibrosis (CF) lung disease is characterized by airway inflammation and airway infection. Nitrites in exhaled breath condensate (EBC‐NO) have been shown to be increased in children and adults with CF compared to healthy controls suggesting its use as a measure of airway inflammation. This longitudinal study aimed to evaluate if repeated measurements of EBC‐NO are helpful in monitoring CF lung disease activity in children. Thirty‐two children with mild CF lung disease (age 10.6 ± 3.3 years) were recruited in two study centers. Follow‐up visits occurred every 3 months over a period of 1 year with a total of five visits. Each visit included a clinical assessment incorporating a modified Shwachman–Kulczycki (SK) score, spirometry, an oropharyngeal swab, or sputum sample for bacterial analysis and an EBC sample analyzed for NO using a spectrophotometric assay. Furthermore at the first and the last visit a chest radiograph was done and scored (Chrispin–Norman (CN) score). There was no correlation of EBC‐NO and parameters of spirometry, SK‐score, or CN‐score. Furthermore, increased EBC‐NO levels did not predict subsequent pulmonary exacerbations. We conclude that repeated measurements of EBC‐NO are not helpful in the longitudinal monitoring of mild CF lung disease in children. Pediatr Pulmonol. 2007; 42:1198–1206. © 2007 Wiley‐Liss, Inc.
Lung disease in niemann–pick disease
Authors: Guillemot Nathalie , Troadec Corinne , de Villemeur Thierry Billette , Clément Annick , Fauroux Brigitte 
Published: October 2007

AbstractBackgroundLung involvement in children with Niemann–Pick disease has rarely been studied systematically.ObjectiveTo assess the involvement of the lung and the value of bronchoalveolar lavage in children with Niemann–Pick diseases.DesignRetrospective analysis of patient records.PatientsThirteen patients, with type A (n = 1), type B (n = 10), and type C (n = 2) Niemann–Pick disease, aged 2 months to 9 years at diagnosis, were included in the study.InterventionsLung involvement was assessed by clinical evaluation, chest radiograph, lung computed tomography (CT) scan, pulmonary function tests, and bronchoalveolar lavage fluid analysis.ResultsRespiratory symptoms were present at diagnosis in 10 patients and developed during follow up in the three other patients. All patients showed signs of interstitial lung disease on chest X‐ray and lung CT scan. Bronchoalveolar lavage fluid analysis (n = 7) revealed a marked accumulation of foamy macrophages (Niemann–Pick cells) in all patients. At follow up, one patient died of respiratory failure, five patients required long term oxygen therapy and seven other patients presented a chronic obstructive pulmonary disease (n = 6) or chronic cough (n = 1).ConclusionLung disease was observed in all the patients included in the present study. Bronchoalveolar lavage may be useful in Niemann–Pick diseases by showing the presence of characteristic Niemann–Pick cells. Pediatr Pulmonol. 2007;42:1207–1214. © 2007 Wiley‐Liss, Inc.
Functional 3D photonic films from polymer beads
Authors: Lange Birger , Fleischhaker Friederike , Zentel Rudolf 
Published: October 2007

AbstractThis paper describes synthesis and properties of polymer opals with a special emphasis on functional opals. Polymer opals are formed from monodisperse polymer colloids by self‐assembly. Their potential applications range from coloring pigments, 3D bicontinuous supports for catalysis to photonic materials. This latter application requires especially the controlled creation of defects and the incorporation of fluorescent materials. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Microscopic analysis of the optical and electronic properties of semiconductor photonic‐crystal structures
Authors: Pasenow Bernhard , Reichelt Matthias , Stroucken Tineke , Meier Torsten , Koch Stephan W. 
Published: October 2007

AbstractThe combination of dielectric photonic crystals and semiconductor nanostructures makes it possible to design many important aspects of the optoelectronic system response. A spatially‐varying dielectric environment induces modifications of the transversal and the longitudinal components of the electromagnetic field which have to be included in the self‐consistent microscopic analysis of the optical properties of hybrid semiconductor photonic‐crystal structures. In this paper, the development of a semiclassical microscopic theory is reviewed. Whereas the classical electromagnetic field is described at the level of Maxwell's equations, a full many‐body quantum theory is used for the interacting electronic excitations in the semiconductor material. Relevant examples of the numerical solutions of the resulting Maxwell semiconductor Bloch equations are presented showing, e.g., characteristic modifications of excitonic absorption spectra, the spatio‐temporal dynamics of electronic wave packets, as well as an increase of the optical gain in properly designed device geometries. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)