bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dependence of apparent diffusion coefficients on axonal spacing, membrane permeability, and diffusion time in spinal cord white matter
Authors: Ford J. Chetley , Hackney David B. , Lavi Ehud , Phillips Micheal , Patel Upen 
Published: March 2007

AbstractWe used a numerical simulation of water self‐diffusion among permeable cylinders to predict the dependence of MR‐based apparent diffusion coefficients in white matter on axonal separation, barrier permeability, and diffusion time (T). The transverse apparent diffusion coefficient (tADC), calculated with simulated diffusion‐sensitizing gradients perpendicular to the axon fibers, remains a function of T down to diffusion times as short as .1 μsec for a range of diffusion barrier permeability. As the diffusion time lengthens, the response of tADC depends on axon diameter, with decreases in tADC occurring earliest, and most dramatically, for the smallest fiber diameter simulated (2 μm). For a given axonal separation, asymptotic values of ADC are determined by permeability alone and are the same for 2‐μm and 11‐μm fibers of equal membrane permeability. The effect of increased relative intracellular volume is manifested primarily in a decrease in tADC at short T. Increases in interaxonal spacing increase the tADC at asymptotically long diffusion times and reduce the dependence on permeability. However, at the widest plausible axonal separations, permeability remains an important determinant of tADC. These simulations may enhance interpretation of measured tADC in the context of the underlying physiologic and structural changes at the cellular level that accompany white‐matter disease.
Fast fluid‐attenuated inversion‐recovery (FLAIR) MRI in the assessment of intraaxial brain tumors
Authors: Essig Macro , Hawighorst Hans , Schoenberg Stefan O. , Engenhart‐Cabillic Rita , Fuss Martin , Debus Juergen , Zuna Ivan , Knopp Michael V. , van Kaick Gerhard 
Published: March 2007

AbstractThis study demonstrates the value of a fast fluid‐attenuated inversion‐recovery (FLAIR) technique in the assessment of primary intraaxial brain tumors. Twenty‐one patients with primary intraaxial brain tumors were examined by T2‐weighted, proton‐density‐weighted fast spin echo, fast FLAIR, and contrast‐enhanced T1‐weighted spin echo using identical slice parameters. The images were evaluated using quantitative and qualitative criteria. Quantitative criteria were tumor‐to‐background and tumor‐to‐cerebrospinal fluid (CSF) contrast and contrast‐to‐noise ratio (CNR). The qualitative evaluation was performed as a multi‐reader analysis concerning lesion detection, lesion delineation, and image artifacts. In the qualitative evaluation, all readers found the fast FLAIR to be superior to fast spin echo in the exact delineation of intraaxial brain tumors (P < .001) and the delineation of enhancing and nonenhancing tumor parts. Fast FLAIR was superior in the delineation of cortically located and small lesions but was limited in lesions adjacent to the ventricles. Fast FLAIR provided a significantly better tumor‐to‐CSF contrast and tumor‐to‐CSF CNR (P < .001). The tumor‐to‐background contrast and tumor‐to‐background CNR of the fast FLAIR images were lower than those of T2‐weighted spin‐echo images but higher than those of proton‐density‐weighted spin‐echo images. FLAIR images had more image artifacts influencing the image interpretation in only two patients. Signal hyperintensities at the ventricular border were present in 92% of the patients. They are common findings in fast FLAIR and should be included into the image interpretation.
In vivo validation of tissue segmentation based on a 3D feature map using both a hamster brain tumor model and stereotactically guided biopsy of brain tumors in man
Authors: Vinitski Simon , Gonzalez Carlos , Andrews David , Knobler Robert , Curtis Mark , Mohamed Feroze , Gordon Jennifer , Khalili Kamel 
Published: March 2007

AbstractThe purpose of this study was to validate our MR tissue segmentation technique using a hamster brain tumor model and malignant brain tumors in man. We used a multispectral tissue segmentation analysis. Three sets of MRI data were included: proton density, T2‐weighted fast spin echo, and T1‐weighted spin echo, as inputs. Three image preprocessing steps included correcting image nonuniformity, application of an anisotropic diffusion type filter, and data point selection by a qualified observer. We used the k‐Nearest Neighbor segmentation algorithm, which does not require prior knowledge of the sample distribution. This choice allowed us to optimize the different tissue clusters present in three‐dimensional (3D) feature space. In vivo validation of the technique was performed in hamsters harboring tumors induced with JC virus‐transformed HJC‐15 cells, as compared to three control animals. Human brain tumors obtained by stereotactically guided biopsy in six patients were also included in the study. Finally, brain tumors were removed from two patients who underwent conventional craniotomy using segmentation‐derived images as a guide. In the hamsters, 10 tissues were correctly identified by segmentation and were confirmed histologically (P < .02). In the patients, there was also a strong correlation between our segmentation results and the tissue obtained by stereotactic biopsy (P < .01). In one of the two patients who underwent open craniotomy, segmentation images were useful in revealing tumor spread into vital areas of the brain (motor area). In conclusion, the results of segmentation correlate well with the tissues in vivo and thus warrant further clinical utilization and evaluation.
Interleaved gradient echo planar (IGEPI) and phase contrast CINE‐PC flow measurements in the renal artery
Authors: Bock Michael , Schoenberg Stefan O. , Schad Lothar R. , Knopp Michael V. , Essig Marco , van Kaick Gerhard 
Published: March 2007

AbstractECG‐gated phase contrast (CINE‐PC) flow measurements in the renal artery help to differentiate between low‐ and high‐grade stenoses. Because conventional CINE‐PC acquisitions with high temporal resolution require acquisition times of several minutes, respiratory motion results in a systematic overestimation of renal artery flow. With the use of an interleaved gradient echo‐planar technique (IGEPI), total measurement times can be shortened to about 30 seconds, while a high spatial and temporal resolution is maintained. In this study, an IGEPI CINE‐PC flow measurement pulse sequence with 16 gradient echoes was compared with a non‐breathheld conventional CINE‐PC technique. Flow‐time curves were measured in volunteers and in patients with suspected renal artery stenosis. With IGEPI CINE‐PC, mean flow velocity, vessel cross‐sectional area, and mean blood flow were substantially lower by 9% to 25%. Contrast‐enhanced 3D MR angiography was used to compare stenosis grading based on flow‐time curve patterns with morphologic grading. With IGEPI CINE‐PC, all high‐grade stenoses (n = 5) were detected, whereas only 66% (n = 3) were found with conventional CINE‐PC.
Assessment of coronary artery patency after stent placement using magnetic resonance angiography
Authors: Duerinckx André J. , Atkinson Dennis , Hurwitz Robert 
Published: March 2007

AbstractThe ability to noninvasively assess the patency of coronary stents would represent a significant advance. We evaluated the safety and ability of two‐dimensional coronary MR angiography In imaging stents and suggesting patency. Coronary MR angiography of 26 coronary stents (Palmaz‐Schatz) was performed in 16 patients 39 to 73 years of age. Studies were performed between 2 and 4 months after stent placement. All patients were symptom free at the time of imaging. Coronary MR angiography was performed with a commercial 1.5‐T MR imager using an electrocardio‐graphically gated pulse sequence with breath‐holding. Images were obtained in mid‐diastole with and without fat suppression. Image artifacts caused by the metal in the stents were clearly visualized in all 26 stents (100% sensitivity for stent detection). Arterial flow signal was seen in the coronary artery or graft distal to the stent in 25 of 26 cases (96%). All patients, except for the one in which distal flow could not be seen, remained symptom free for >2 years. The distribution of stent locations was as follows: 10 in the right coronary artery (RCA), 10 in the left anterior descending coronary artery (LAD), 2 in the left circumflex coronary artery, and 4 in saphenous vein grafts (SVGs) to RCA. One patient had 2 RCA and 2 LAD stents, one had 3 RCA and 1 LAD stents, one had 3 SVG stents, and two had double RCA stents. Coronary MR angiography is safe for noninvasive imaging of coronary stents, and in the proper clinical setting, it can be used to help suggest patency.
Characterization of novel myelin components 3‐O‐acetyl‐sphingosine galactosylceramides by electrospray ionization Q‐TOF MS and MS/CID‐MS of Li+ adducts
Authors: Bennion Beau , Dasgupta Somsankar , Hogan Edward L. , Levery Steven B. 
Published: March 2007

AbstractGlycosphingolipids with Rf values higher than those of monoglycosylceramides (MGCs) in normal phase HPTLC appear to be normal components of myelin. A series of such low polarity components, referred to as ‘fast moving cerebrosides’ (FMCs), have been isolated from rat brain, and two of these fractions (FMC‐1 and FMC‐2) were found to be novel derivatives of galactosylceramide (GalCer) exhibiting O‐acetylation at the 3‐hydroxy group of the sphingoid moiety, and incorporating either non‐hydroxy or 2‐hydroxy fatty‐N‐acylation (Dasgupta S, Levery SB, Hogan EL. J. Lipid Res. 2002; 43: 751–761). Similar to the parent compounds, the 3‐O‐acetyl‐sphingoid derivatives exhibit considerable diversity with respect to fatty‐N‐acyl chain length, manifested by heterogeneous molecular ion (Li+ adduct) profiles. However, a detailed analysis of the individual molecular variants (‘lipoforms’), e.g. by tandem MS/CID‐MS analysis, was not carried out. In addition, several other FMCs distinguished by even lower polarity (higher HPTLC Rf values) were isolated but have remained uncharacterized. For this study, analysis of both the known and unknown FMC components was carried out by positive ion ESI‐MS and MS/CID‐MS of their Li+ adducts on a Q‐TOF mass spectrometer. Since a Q‐TOF instrument has not yet been applied to MS of lithiated cerebrosides and FMCs, MS/CID‐MS spectra of bovine brain GalCer (both types) and the previously characterized rat brain FMCs (FMC‐1 and FMC‐2), having 3‐O‐acetylation of the sphingoid, were systematically acquired and their fragmentation behavior compared. This was followed by systematic analysis of previously uncharacterized FMC fractions (FMC‐3 through FMC‐5/6/7). The GalCer and FMC components proved to be amenable to analysis by this technique, and the data confirm that the latter are all related 3‐O‐acetyl‐sphingoid derivatives, with the higher Rf components carrying additional O‐acetyl modifications on the galactosyl residue, which further reduce their polarity. The utility of the technique, the structures of unknown FMCs, and their characteristic fragmentation patterns are described. Copyright © 2007 John Wiley & Sons, Ltd.
Dissipation of charge on MALDI‐TOF polymeric chips using an electron‐acceptor: analysis of proteins
Authors: Ibáñez Alfredo J. , Muck Alexander , Svatoš Aleš 
Published: March 2007

AbstractDisposable polymeric devices used for direct sample pretreatment/signal enhancement and MALDI‐MS analyses of biomolecules suffer from the accumulation of electric charge and related positive mass shifts due to photoelectric effects on non‐conductive surfaces after irradiation with lasers. The effects of surface charging on the mass shift of protein spectra during MALDI‐TOF/MS measurements on copolymeric sample array chips were studied. Methyl viologen is used to monitor the development of charge and is demonstrated to be an effective electron scavenger. The use of such reducible species leads to increased accuracy, signal homogeneity, and resolution for mass spectral measurements of proteins in mixtures with sinapinic and 2,5‐dihydroxybenzoic (DHB) acids. This approach can be used on a wide range of nonconductive support materials. Copyright © 2007 John Wiley & Sons, Ltd.
Early Indicators of Prognosis in Fulminant Hepatic Failure
Authors: Dhiman Radha K. , Jain Sanjay , Maheshwari Uma , Bhalla Ashish , Sharma Navneet , Ahluwalia Jasmina , Duseja Ajay , Chawla Yogesh 
Published: March 2007

Abstract
While King's Hospital Criteria (KCH) criteria are used worldwide, the Model for End-Stage Liver Disease (MELD) is a more recently developed scoring system that has been validated as an independent predictor of patient survival in conditions for liver transplantation (LT). The aim of the present study was to compare MELD and KCH criteria with other early clinical prognostic indicators (CPI) in a cohort of patients with fulminant hepatic failure (FHF). A total of 144 patients (mean age 31.7 ± 14.7 yr; range 12–82 yr; 62 males) with FHF due to acute viral hepatitis were included into the study. Variables found significant on univariate analysis were entered into a multivariate logistic regression analysis. A total of 52 (36.1%) patients survived, the remaining 92 (63.9%) died. Univariate analysis showed that age, duration of jaundice, jaundice-encephalopathy interval (JEI), grade of encephalopathy, presence of cerebral edema, bilirubin, prothrombin time, creatinine, and MELD score were significantly different between survivors and nonsurvivors. Multivariate logistic regression identified 6 independent CPI of adverse outcome on admission: age ≥50 yr, JEI >7 days, grade 3 or 4 encephalopathy, presence of cerebral edema, prothrombin time ≥35 seconds, and creatinine ≥1.5 mg/dL. Presence of any 3 of 6 CPI was optimum in identifying survivors and nonsurvivors. A MELD score of ≥33 was found to be best discriminant between survivors and nonsurvivors by the construction of receiver operating characteristic (ROC) curves. Any 3 CPI were superior to MELD and KCH criteria in predicting the outcome (c-statistic [95% confidence interval]: CPI 0.802 [0.726–0.878], MELD 0.717 [0.636–0.789], and KCH criteria 0.676 (0.588–0.764); P values: CPI vs. MELD 0.045, CPI vs. KCH criteria 0.019, and MELD vs. KCH criteria 0.472). In conclusion, MELD and KCH criteria are not as useful as a combination of other early CPI in predicting adverse outcome in patients with FHF due to acute viral hepatitis. Liver Transpl, 2007. © 2007 AASLD.
Cirrhosis After Orthotopic Liver Transplantation in the Absence of Primary Disease Recurrence
Authors: Seyam Moataz , Neuberger James M. , Gunson Bridget K. , Hübscher Stefan G. 
Published: March 2007

Abstract
Liver allograft cirrhosis is a relatively uncommon complication of liver transplantation. Most cases can be attributed to disease recurrence, particularly recurrent hepatitis C. Little is known about the frequency, etiology, and natural history of liver allograft cirrhosis occurring without evidence of recurrent disease. The aim of the present study was to review the clinicopathological features in this group of patients. We retrospectively reviewed data from all adult patients who were transplanted between 1982 and 2002 and survived >12 months after orthotopic liver transplantation (n = 1,287). Cases of histologically proven cirrhosis were identified from histopathological data entered into the Liver Unit Database. A total of 48 patients (3.7%) developed cirrhosis. In 29 of them, cirrhosis could be attributed to recurrent disease (hepatitis C, 11; hepatitis B, 4; autoimmune hepatitis, 4; primary biliary cirrhosis, 2; primary sclerosing cholangitis, 3; nonalcoholic steatohepatitis, 4; alcoholic liver disease, 1). In 9 of the 19 patients without evidence of disease recurrence, another cause of cirrhosis could be identified (de novo autoimmune hepatitis, 4; biliary complications, 4; acquired hepatitis B, 1). In the remaining 10 cases, the cause of cirrhosis remained unknown; their previous biopsies had shown features of chronic hepatitis of uncertain etiology. Three patients in this group died, and the remaining 7 are alive with good graft function 3–12 years after cirrhosis was first diagnosed. The prevalence of “cryptogenic” posttransplant cirrhosis was significantly higher in patients initially transplanted for fulminant seronegative hepatitis (6%) than in those transplanted for other diseases (0.3%). In conclusion, posttransplant cirrhosis without disease recurrence is uncommon, but it is more frequent in patients transplanted for fulminant seronegative hepatitis. Chronic hepatitis is the most frequent underlying pathological process in cases where the cause of cirrhosis remains uncertain. Liver Transpl, 2007. © 2007 AASLD.
Acute Liver Failure in Spain
Authors: Escorsell Àngels , Mas Antoni , de la Mata Manuel 
Published: March 2007

Abstract

The cause of acute liver failure (ALF) is a major determinant of its outcome. Acetaminophen (paracetamol) overdose is a leading cause of ALF in some developed countries, whereas in others, such as Spain, it is extremely rare. To analyze the etiology, characteristics, and outcome of ALF in Spain, we performed a retrospective analysis of 267 patients whom we observed from 1992 to 2000. Seventeen tertiary-care hospitals with active liver transplantation (LT) programs contributed data. Causes of ALF were viral hepatitis in 98 (37%; hepatitis B virus in 75 patients), unknown in 86 (32%), drug or toxic reactions in 52 (19.5%; acetaminophen overdose in 6), and miscellaneous in 31 (11.6%). Overall survival was 58%. LT was performed in 150 patients, with a survival of 69%. Despite fulfilling criteria, 51 patients were not transplanted because of contraindications; their survival was only 7.8%. Forty-seven (85.5%) of 55 patients without transplant criteria survived. Hepatitis B virus is the most common cause of ALF in Spain, although the origin of 30% of cases remains undetermined. Acetaminophen overdose represents a very rare cause of ALF. LT was performed in >50% of cases. Patients without transplant criteria had a very good prognosis; those who fulfilled these criteria but who had contraindications for transplantation had a high mortality rate. Liver Transpl, 2007. © 2007 AASLD.
Effect of Polycarboxylate Blocks on the Amidase Activity of Trypsin through Complexation with PEG/Polycarboxylate Block Ionomers
Authors: Harada Atsushi , Yoshioka Yuriko , Kawamura Akifumi , Kojima Chie , Kono Kenji 
Published: March 2007

AbstractThe amidase reaction of trypsin, which is a member of the serine proteinase family, is accelerated by its complexation with block ionomers containing a polycarboxylate block, such as PEG‐PAA, PEG‐PGA, or PEG‐PMA. PEG‐PAA and PEG‐PGA had similar effects, causing an increase in the kcat value and a shift in the pH profile to a lower pH region. On the other hand, PEG‐PMA showed not only an increase in the kcat value, but also a decrease in the activation energy; however, there was no shift in the pH dependence of the initial reaction rate. Such differences might be induced by the difference in pKa values of the polycarboxylate block in block ionomers.magnified image
Modification of Gelatin by Reaction with 1,6‐Diisocyanatohexane
Authors: Bertoldo Monica , Bronco Simona , Gragnoli Tania , Ciardelli Francesco 
Published: March 2007

Abstract1,6‐Diisocyanatohexane and dimethyl sulfoxide were exploited as crosslinking agent and reaction solvent, respectively, for gelatin modification. Crosslinked samples were fractionated and analyzed by thermogravimetric analysis, infrared spectroscopy, acid and base titrations, and swelling measurements. The yield of crosslinking was found to increase with increasing diisocyanate and gelatin concentrations and the amount of bound crosslinker was evaluated. The chemical analysis of the reaction products allowed the process parameters to be related to the properties of the textile/gelatin composites. For this purpose poly(propylene)‐, poly(ethylene terephthalate)‐, and cotton‐based textiles were treated to prepare soft and dimensionally stable supported materials with a gel phase composed of gelatin.magnified image
Oligosaccharide‐Modified Poly(propyleneimine) Dendrimers: Synthesis, Structure Determination, and CuII Complexation
Authors: Appelhans Dietmar , Zhong Yong , Komber Hartmut , Friedel Peter , Oertel Ulrich , Scheler Ulrich , Morgner Nina , Kuckling Dirk , Richter Sven , Seidel Jürgen , Brutschy Bernhard , Voit Brigitte 
Published: March 2007

AbstractThe multiple application of reductive amination on primary amino groups of first and second generation poly(propyleneimine) dendrimers is used as a one‐pot approach to introduce twice the amount of the oligosaccharide units as surface groups, compared to initially present amino groups in the first and second generation dendrimers. This was proven by 1H NMR, MALDI‐TOF‐MS, and LILBID‐MS analysis. The size of these dendrimers was determined by the hydrodynamic radius using pulsed field gradient NMR and dynamic light scattering. Molecular modeling confirmed the presence of dense‐shell dendrimers. These dendrimers exhibit a generation dependent CuII/dendrimer ratio in an aqueous environment, highlighting these materials as possible metal‐carrier systems with a well‐defined oligosaccharide protection shell for application in a biological environment.magnified image
Interval scheduling: A survey
Authors: Kolen Antoon W.J. , Lenstra Jan Karel , Papadimitriou Christos H. , Spieksma Frits C.R. 
Published: March 2007

AbstractIn interval scheduling, not only the processing times of the jobs but also their starting times are given. This article surveys the area of interval scheduling and presents proofs of results that have been known within the community for some time. We first review the complexity and approximability of different variants of interval scheduling problems. Next, we motivate the relevance of interval scheduling problems by providing an overview of applications that have appeared in literature. Finally, we focus on algorithmic results for two important variants of interval scheduling problems. In one variant we deal with nonidentical machines: instead of each machine being continuously available, there is a given interval for each machine in which it is available. In another variant, the machines are continuously available but they are ordered, and each job has a given “maximal” machine on which it can be processed. We investigate the complexity of these problems and describe algorithms for their solution. © 2007 Wiley Periodicals, Inc. Naval Research Logistics, 2007
A saturated discrete particle model and characteristic‐based SPH method in granular materials
Authors: Li Xikui , Chu Xihua , Sheng D. C. 
Published: March 2007

AbstractBased on the discrete particle model for solid‐phase deformation of granular materials consisting of dry particulate assemblages, a discrete particle–continuum model for modelling the coupled hydro‐mechanical behaviour in saturated granular materials is developed. The motion of the interstitial fluid is described by two parallel continuum schemes governed by the averaged incompressible N–S equations and Darcy's law, respectively, where the latter one can be regarded as a degraded case of the former.Owing to the merits in both Lagrangian and mesh‐free characters, the characteristic‐based smoothed particle hydrodynamics (SPH) method is proposed in this paper for modelling pore fluid flows relative to the deformed solid phase that is modelled as packed assemblages of interacting discrete particles. It is assumed that the formulation is Lagrangian with the co‐ordinate system transferring with the movement of the solid particles. The assumed continuous fluid field is discretized into a finite set of Lagrangian (material) points with their number equal to that of solid particles situated in the computational domain. An explicit meshless scheme for granular materials with interstitial water is formulated. Numerical results illustrate the capability and performance of the present model in modelling the fluid–solid interaction and deformation in granular materials saturated with water. Copyright © 2007 John Wiley & Sons, Ltd.