bluuebunny/crossref_metadata_2025_split huggingface dataset:
Functional hepatocyte cation compartmentation demonstrated with 133Cs NMR
Authors: Wellard R.M. , Adam W.R. 
Published: November 2002

AbstractThis study utilized the large intrinsic chemical shift range of 133Cs, a potassium congener, in an NMR study of intracellular cation distribution. It demonstrates two distinct intracellular environments in isolated perfused hepatocytes from cesium‐fed rats, evident as compartments with different 133Cs chemical shifts and containing different proportions of total detected cesium. The chemical shifts of the two intracellular compartments were 2.44 ± 0.07 and 1.21 ± 0.18 ppm, relative to the cesium signal from the perfusate. The observation of two distinct intracellular cesium signals suggests slow exchange on an NMR chemical shift time‐scale (k exchange > 0.02 s). The area of the high‐frequency component represented 62 ± 10% (N = 12) of the total intracellular cesium signal. Manipulation of the intracellular environment using anoxia with aglycemia or digitonin produced changes in the distribution between the two intracellular compartments, showing their dynamic nature. Changes measured in association with metabolic manipulation suggest cytoplasm and mitochondria as the origin of the high and low‐frequency intracellular peaks, respectively. Magn Reson Med 48:810–818, 2002. © 2002 Wiley‐Liss, Inc.
Method to correct for the effects of limited spatial resolution in phase‐contrast flow MRI measurements
Authors: Lagerstrand K.M , Lehmann H. , Starck G. , Vikhoff‐Baaz B. , Ekholm S. , Forssell‐Aronsson E. 
Published: November 2002

AbstractPhase‐contrast (PC) magnetic resonance imaging (MRI) flow measurements suffer from the effect of the point spread function (PSF) due to the limited sampling of k‐space. The PSF, which in this case is a sinc function, deforms the flow profile and forms a ringing pattern around the vessel. In this work, an empirical method is presented that corrects for errors due to the deformation of the flow profile. The ringing pattern is used to obtain a well‐defined vessel segmentation, which after correction provides more accurate vessel radius and volume flow rate (VFR). The correction method was developed from phantom measurements at constant flow and applied on phantom measurements at moderately pulsatile flow. After correction, the error of the estimated tube radius and the VFR was less than 10% and 5%, respectively. Corresponding errors without correction overestimated the radius by 60% and the VFR by 35%. Preliminary results indicate that the method is also valid in vivo. The variation in the estimated radius and VFR for different spatial resolution decreased when the method was applied. The presented method gives a more accurate estimation of the radius and VFR in vessels of the size of a few pixels without prior knowledge about the true vessel radius. Magn Reson Med 48:883–889, 2002. © 2002 Wiley‐Liss, Inc.
Myocardial viability imaging using Gd‐DTPA: Physiological modeling of infarcted myocardium, and impact on injection strategy and imaging time
Authors: Moran G.R. , Thornhill R.E. , Sykes J. , Prato F.S. 
Published: November 2002

AbstractResults of simulations are shown which illustrate how the concentration‐time curves of an extravascular extracellular (EVEC) contrast agent, such as Gd‐DTPA, vary in myocardial tissue. The simulations show that the variable permeability of dead myocytes within a recent myocardial infarction will significantly alter delayed enhancement patterns following a bolus injection, invariably reducing the sensitivity of this technique for the detection of permanently damaged tissue. It is further predicted that if the bolus injection is followed by a suitably selected constant infusion, the infarct size and infarct volume of distribution may be more accurately determined, even though the degree of enhancement of an infarcted region (with normal flow) above normal tissue is slightly higher for the bolus technique within the first 30 min following the injection. The degree of enhancement of an infarcted region (with normal flow) above normal tissue was comparable between the two techniques at the point in the constant infusion at which the volume of contrast injected was the same as in the bolus case, i.e., at approximately 30 min after the bolus injection. The constant infusion approach became superior thereafter as overall tissue concentrations became greater in both normal and infarcted tissue, and these concentrations remained more stable with the constant infusion approach. Preliminary experimental results in a canine model of infarction/reperfusion illustrated a delayed wash‐in of contrast agent in infarcted tissue, which may be explained by a physiological model in which dead myocytes in infarcted myocardium have non‐infinite permeability. Magn Reson Med 48:791–800, 2002. © 2002 Wiley‐Liss, Inc.
MR angiography with a new rapid‐clearance blood pool agent: Initial experience in rabbits
Authors: Ruehm Stefan G. , Christina Heidi , Violas Xavier , Corot Claire , Debatin Jörg F. 
Published: November 2002

AbstractThe purpose of this study was to assess a new Gd‐based macromolecular intravascular contrast agent (P792, Vistarem®; Laboratoire Guerbet, Aulnay sous Bois, France) for MR angiography (MRA). P792 is a macrocyclic gadolinium compound based on a gadoterate meglumine structure substituted by hydrophilic arms. In vitro imaging of phantoms containing varying concentrations of P792 and gadoterate meglumine (Gd‐DOTA) was performed. In rabbits (N = 5), arterial concentrations for P792 and Gd‐DOTA were determined, and in vivo 3D MRA was performed. For gadolinium concentrations ranging from 200 to 3000 μmol/l, in vitro imaging showed higher SNR values for P792 compared to Gd‐DOTA. Determination of arterial Gd concentration showed comparable bolus phase curves for P792 and Gd‐DOTA. With P792, higher concentrations were obtained due to a restricted diffusion into the interstitial space. P792 allowed acquisition of high‐quality MR angiograms. Image quality was rated as superior for P792 in the post‐bolus phase images. In conclusion, P792 appears to be well suited for high‐quality first‐pass and equilibrium‐phase MRA. The intravascular properties lead to an excellent signal in the vasculature, with limited background enhancement. Since the agent is rapidly renally excreted, it should be well suited for perfusion and permeability imaging. Magn Reson Med 48:844–851, 2002. © 2002 Wiley‐Liss, Inc.
T1‐insensitive flow suppression using quadruple inversion‐recovery
Authors: Yarnykh Vasily L. , Yuan Chun 
Published: November 2002

AbstractA new flow suppression method has been proposed for the acquisition of blood‐suppressed (black‐blood) images in combination with administration of a positive contrast agent. The technique employs the quadruple inversion‐recovery (QIR) preparative pulse sequence, which consists of two double‐inversion modules followed by two delays. Within each double inversion, a nonselective RF pulse is immediately followed by a slice‐selective one. The time intervals of the sequence can be calculated using an algorithm based on minimization of the variation of a signal equation over an entire range of T1 occurring in blood before and after contrast administration. QIR is highly insensitive to variations of T1, providing efficient suppression of a flow signal with T1 in a range of 200–1200 ms. The technique utilizes identical scan parameters for pre‐ and postcontrast acquisition, and thus allows reliable quantitative interpretation of contrast enhancement (CE). The clinical application of QIR was demonstrated in high‐resolution, contrast‐enhanced, black‐blood imaging of atherosclerotic plzzaque. Magn Reson Med 48:899–905, 2002. © 2002 Wiley‐Liss, Inc.
Observation and identification of metabolites emerging during postmortem decomposition of brain tissue by means of in situ1H‐magnetic resonance spectroscopy
Authors: Ith Michael , Bigler Peter , Scheurer Eva , Kreis Roland , Hofmann Lucie , Dirnhofer Richard , Boesch Chris 
Published: November 2002

AbstractPostmortem decomposition of brain tissue was investigated by1H‐magnetic resonance spectroscopy (MRS) in a sheep head model and selected human cases. Aiming at the eventual estimation of postmortem intervals in forensic medicine, this study focuses on the characterization and identification of newly observed metabolites. In situ single‐voxel1H‐MRS at 1.5 T was complemented by multidimensional homo‐ and heteronuclear high‐resolution NMR spectroscopy of an extract of sheep brain tissue. The inclusion of spectra of model solutions in the program LC Model confirmed the assignments in situ. The first postmortem phase was characterized mainly by changes in the concentrations of metabolites usually observed in vivo and by the appearance of previously reported decay products. About 3 days postmortem, new metabolites, including free trimethylammonium, propionate, butyrate, and iso‐butyrate, started to appear in situ. Since the observed metabolites and the time course is comparable in sheep and human brain tissue, the model system seems to be appropriate. Magn Reson Med 48:915–920, 2002. © 2002 Wiley‐Liss, Inc.
Real‐time changes in 1H and 31P NMR spectra of malignant human mammary epithelial cells during treatment with the anti‐inflammatory agent indomethacin
Authors: Glunde Kristine , Ackerstaff Ellen , Natarajan Kshama , Artemov Dmitri , Bhujwalla Zaver M. 
Published: November 2002

AbstractCholine metabolites in malignant human mammary epithelial cells (HMECs) are significantly altered compared to normal HMECs. 1H NMR studies of cell extracts have shown that treatment of malignant HMECs with a nonsteroidal anti‐inflammatory agent, indomethacin, results in a distribution of choline compounds more typical of nonmalignant HMECs. To follow the time course of these changes, in this study real‐time monitoring of choline compounds of malignant MDA‐MB‐231 cells was performed during treatment with indomethacin. The contribution of changes in intra‐ and extracellular pH to changes in choline compounds was also examined. Changes in water‐soluble choline phospholipid metabolites, such as phosphocholine (PC), glycerophosphocholine (GPC), and total choline, as well as intracellular pH, were monitored by 31P and diffusion‐weighted 1H NMR spectroscopy of living cells using an NMR‐compatible perfusion system. An accumulation of GPC and a decrease of PC, resulting in an increased [GPC]/[PC] ratio, were detected within 2 hr of treatment with 200 μM indomethacin. Since a decreased [GPC]/[PC] ratio is associated with increased malignancy, these data demonstrate that nonspecific cyclooxygenase inhibition by indomethacin alters the choline metabolite profile of malignant cells towards a less malignant phenotype. These changes were not related to alterations of intra‐ or extracellular pH. Magn Reson Med 48:819–825, 2002. © 2002 Wiley‐Liss, Inc.
Separating changes in the intra‐ and extracellular water apparent diffusion coefficient following focal cerebral ischemia in the rat brain
Authors: Silva Matthew D. , Omae Tsuyoshi , Helmer Karl G. , Li Fuhai , Fisher Marc , Sotak Christopher H. 
Published: November 2002

AbstractSelective intracellular (IC) and extracellular (EC) brain water apparent diffusion coefficient (ADC) values were measured in normal and ischemic rat brain. Selective T1‐relaxation enhancement of the EC water, using intracerebroventricular (ICV) infusion of an NMR contrast reagent (CR), was used to separate the IC and EC signal contributions. In the CR‐infused, normal brain (n = 4), T1 = 235 ± 10 ms and T2 = 46 ± 2 ms for IC water (85%) and T1 = 48 ± 8 ms and T2 = 6 ± 2 ms for EC water (15%). Volume‐localized ADCz (z‐gradient axis) values were 0.90 ± 0.02 (EC+IC), 0.81 ± 0.05 (IC), 0.51 ± 0.02 (EC+IC), and 0.53 ± 0.07 (IC), for normal, CR‐infused, ischemic, and ischemic/CR‐infused groups, respectively (ADC values are ×10‐3 mm2/s; n = 5 for each group). Imaging ADCz values were 0.81 ± 0.03 (EC+IC), 0.75 ± 0.05 (IC), 0.51 ± 0.04 (EC+IC), and 0.52 ± 0.05 (IC), respectively, for the same groups. Imaging ADCav (average diffusivity) values for the same groups were 0.70 ± 0.05 (EC+IC), 0.69 ± 0.06 (IC), 0.45 ± 0.06 (EC+IC), and 0.44 ± 0.06 (IC), respectively. These results suggest that the IC water ADC determines the overall water ADC value in normal and ischemic rat brain. Magn Reson Med 48:826–837, 2002. © 2002 Wiley‐Liss, Inc.
Optimization of static field homogeneity in human brain using diamagnetic passive shims
Authors: Wilson James L. , Jenkinson Mark , Jezzard Peter 
Published: November 2002

AbstractThese preliminary studies demonstrate that static field inhomogeneity in the human inferior frontal cortex (IFC) is significantly diminished through placement of a small amount of strongly diamagnetic material in the roof of the mouth. As a result, susceptibility‐related image artifacts in this region, as observed in blood oxygen level dependent (BOLD) functional MRI (fMRI), are considerably decreased without compromising the spatial or temporal resolution of the study. Simulations of the static field utilizing perturbation theory are shown, which support the experimental results. The limitations and possible future developments of the technique are described. The application of diamagnetic passive shimming on other regions of the brain is also discussed. Routine use of the proposed method within fMRI studies is practicable through subject‐specific optimization of the technique utilizing the simulation algorithm. Magn Reson Med 48:906–914, 2002. © 2002 Wiley‐Liss, Inc.
Evidence that both fast and slow water ADC components arise from intracellular space
Authors: Sehy Jonathan V. , Ackerman Joseph J.H. , Neil Jeffrey J. 
Published: November 2002

AbstractEvaluation of water diffusion in the brain has revealed both fast‐ and slow‐diffusing water populations. It has been suggested that these populations represent extra‐ and intracellular water, respectively. We have identified and characterized both populations in the intracellular space of the Xenopus oocyte. We have also determined their T1 and T2 relaxation properties. The fast and slow intracellular populations have diffusion coefficients of 1.06 ± 0.05 μm2/ms and 0.16 ± 0.02 μm2/ms, respectively, with the fast fraction representing 89% ± 1% of the total water signal. These values are quite similar to those for total water in brain and are observed in the absence of signal from the perfusate (extracellular) water population. Volumetric swelling (16% ± 4%) of the oocyte in hypoosmotic media increased the diffusion coefficients of both intracellular populations (fast = 1.27 ± 0.03 μm2/ms, slow = 0.22 ± 0.02 μm2/ms), but did not change their relative signal fractions. This phenomenon runs counter to the effects observed in brain injury, following which the apparent diffusion coefficient (ADC) decreases 30–50%. The results presented herein suggest that this ADC decrease in brain occurs despite cell swelling, which by itself would be expected to induce an increase in intracellular diffusion coefficients. Magn Reson Med 48:765–770, 2002. © 2002 Wiley‐Liss, Inc.
A load cluster management system using SNMP and web
Authors: Kim Myung‐Sup , Choi Mi‐Joung , Hong James W. 
Published: November 2002

AbstractClustered servers for Internet service is a popular solution to cope with the explosive increase in client requests. The high probability of service failure in cluster servers make the cluster management system necessary to provide high availability and convenient administrator control. In this paper, we present the design and implementation of a load cluster management system (LCMS) based on SNMP and Web technology. Our LCMS implementation has been deployed on a commercial ultra‐dense server. Copyright © 2002 John Wiley & Sons, Ltd.
Transparent bridging support for Bluetooth–IP service interworking
Authors: Chen Jiann‐Liang , Yen Ka‐Chin 
Published: November 2002

AbstractA PC‐based transparent gateway for interconnecting Bluetooth Piconets and IP local area networks (LAN) was designed in our research. The essential function of this designed Bluetooth‐IP gateway is to achieve a seamless integration among home appliances, networking elements and multi‐systems using the address resolution protocol (ARP) and connection management scheme. The key techniques developed, as well as the performance analysis in terms of queue length, loss rate, throughput and transmission delay are explored in this research. The results allow us to determine the value of the optimal command and infer the maximum queue length requirements such that the service quality is kept at an acceptance level. Copyright © 2002 John Wiley & Sons, Ltd.
Construct validity of the adjustment scales for children and adolescents and the preschool and kindergarten behavior scales: Convergent and divergent evidence
Authors: Canivez Gary L. , Rains Jaime D. 
Published: November 2002

AbstractConstruct validity (convergent and divergent) of the Adjustment Scales for Children and Adolescents (ASCA; McDermott, Marston, & Stott, 1993) and the Preschool and Kindergarten Behavior Scales (PKBS; Merrell, 1994a) is presented. Regular classroom teachers (n = 38) randomly selected 5‐ and 6‐year‐old children (N = 123) and rated them on the ASCA and PKBS in counterbalanced order. Convergent evidence of construct validity was observed for the PKBS Externalizing Problems scale and the ASCA Overactivity syndrome. Divergent evidence of construct validity was provided for the PKBS Externalizing Problems scale and ASCA Underactivity syndrome. Convergent and divergent evidence of construct validity for the PKBS Internalizing Problems scale and ASCA Overactivity and Underactivity syndromes was mixed. Results were identical to those of Canivez and Bordenkircher (2002). © 2002 Wiley Periodicals, Inc. Psychol Schs 39: 621–633, 2002.
Modularity, strategic flexibility, and firm performance: a study of the home appliance industry
Authors: Worren Nicolay , Moore Karl , Cardona Pablo 
Published: November 2002

AbstractRecent theorizing has proposed that modular product and process architectures are key enablers of strategic flexibility. We formulated an integrative conceptual model encompassing antecedents, contributing factors, and outcomes of modularity. We then tested this model on data from managers in U.S. and U.K. home appliance companies using structural equations modeling. The results indicate a positive relationship between modular product architectures and performance, with product model variety as a mediating variable. The results also highlight linkages between perceptions of market context and the use of modular products architectures, and between complementary organizational capabilities and firm performance. Copyright © 2002 John Wiley & Sons, Ltd.
Return predictability in African stock markets
Authors: Appiah‐Kusi Joe , Menyah Kojo 
Published: November 2002

AbstractThis paper models weekly index returns adjusted for thin trading as a nonlinear autoregressive process with conditional heteroscedasticity to investigate the weak‐form pricing efficiency of 11 African stock markets. Specifically, the use of the EGARCH‐M model allows us to capture how conditional volatility affects the pricing process without imposing undue restrictions on the parameters of the conditional variance equation. On the basis of such a robust model, we are able to reject the evidence in prior studies that the Nigerian stock market is weak‐form efficient. On the other hand, we confirm extant results that the markets in Egypt, Kenya, and Zimbabwe are efficient while that of South Africa is not weak‐form efficient. We also generate new results, which point to the efficiency of the stock markets in Mauritius and Morocco, while the markets in Botswana, Ghana, Ivory Coast, and Swaziland are not consistent with weak‐form efficiency.
Increased frequency of cytochrome P450 2D6 poor metabolizers among patients with metoprolol‐associated adverse effects
Authors: Wuttke Henrike , Rau Thomas , Heide Roland , Bergmann Klaus , Böhm Michael , Weil Joachim , Werner Dierk , Eschenhagen Thomas 
Published: November 2002

ObjectiveThe CYP2D6 genotype is a major determinant of interindividual differences in metoprolol plasma clearance. Cytochrome P450 2D6 (CYP2D6) poor metabolizers exhibit 3‐ to 10‐fold higher plasma concentrations after administration of metoprolol than extensive metabolizers. However, the impact of the CYP2D6 genotype on the occurrence of adverse effects of metoprolol remains controversial. This study addressed whether the incidence of poor metabolizers was higher in patients with metoprolol‐associated adverse effects than in the German population at large.MethodsApproximately 1200 German physicians were asked to report on patients who had experienced pronounced adverse effects in association with administration of metoprolol. CYP2D6 genotypes were determined with a combination of allele‐specific polymerase chain reaction and polymerase chain reaction‐restriction fragment length polymorphism. The adverse effects, consisting of symptoms related to β‐adrenergic receptor blockade and nonspecific symptoms, were recorded by use of a standardized questionnaire.ResultsTwenty‐four patients were included in the study. Nine patients had 2 null alleles (poor metabolizer genotype; 38%); the remaining 15 had either 1 null allele (n = 7) or no null alleles (n = 8). Therefore the occurrences of poor metabolizer genotypes in the study population were 4.9‐ and 5.2‐fold more frequent, respectively, than that found in unselected members of the German population in two large studies (P < .0001; χ2 test).ConclusionsThese data showed that CYP2D6 poor metabolizers had a 5‐fold higher risk for development of adverse effects during metoprolol treatment than patients who were not poor metabolizers. Because the absolute risk of adverse effects of metoprolol is unknown, the clinical relevance of the CYP2D6 genotype for metoprolol therapy has to be determined in a prospective manner.Clinical Pharmacology & Therapeutics (2002) 72, 429–437; doi: 10.1067/mcp.2002.127111