bluuebunny/crossref_metadata_2025 huggingface dataset:
Radiation stimulates HGF receptor/c‐Met expression that leads to amplifying cellular response to HGF stimulation via upregulated receptor tyrosine phosphorylation and MAP kinase activity in pancreatic cancer cells
Authors: Qian Li‐Wu , Mizumoto Kazuhiro , Inadome Naoki , Nagai Eishi , Sato Norihiro , Matsumoto Kunio , Nakamura Toshikazu , Tanaka Masao
Published: February 2003

Hepatocyte growth factor (HGF) is a stromal‐derived cytokine that plays a crucial role in invasion and metastasis of tumor cells through the interaction with HGF receptor, c‐Met, which is frequently overexpressed in pancreatic cancer. The present study was designed to investigate the change in HGF receptor and HGF‐mediated signaling after irradiation in pancreatic cancer cells. Six cell lines from human pancreatic cancer were included in the study. Gamma‐radiation was used for irradiation treatment. The changes in expression levels of c‐Met were evaluated by immunoblot and confirmed morphologically by indirect immunofluorescence staining. Whether the resultant alteration in c‐Met would cascade as biologically usable signals upon HGF ligation was traced by receptor tyrosine phosphorylation analysis and mitogen activated protein kinase (MAP kinase or MAPK) activity assay. The various biological responses to HGF (including cell proliferation, cell scattering, migration and invasion) were evaluated as well. We also used a 4‐kringle antagonist of HGF, NK4, to block the HGF/c‐Met signaling pathway. Both immunoblot and immunofluorescent analysis showed moderate increased expression of c‐Met in 3 of 6 pancreatic cancer cell lines after irradiation. The actions seemed to be dose‐responsible, which began at 3 hr and reached its peak value at 24 hr following irradiation. The radiation‐increased expression of c‐Met could transform into magnifying receptor tyrosine phosphorylation reaction and MAP kinase activity once the ligand was added, fairly corresponding with alteration in the receptor. Sequentially, the cellular responses to HGF, including scattering and invasion but not proliferation, were enhanced. Also, in the presence of HGF, the elevated receptor could help to recover the radiation‐compromised cell migration. A recombinant HGF antagonist, NK4 could effectively block these aberrant effects activated by irradiation both in molecular and cellular levels, thus suggesting the deep involvement of the c‐Met/HGF pathway in the enhanced malignant potential after irradiation. These results suggest that radiation may promote HGF‐induced malignant biological behaviors of certain pancreatic cancer cells through the up‐regulated HGF/c‐Met signal pathway. Selectively targeted blockade of the HGF/c‐Met pathway could help to abolish the enforced malignant behavior of tumor cells by irradiation and therefore may improve the efficacy of radiotherapy for pancreatic cancer. © 2003 Wiley‐Liss, Inc.
Susceptibility of multidrug resistance tumor cells to apoptosis induction by histone deacetylase inhibitors
Authors: Castro‐Galache Maria D. , Ferragut Jose A. , Barbera Victor M. , Martín‐Orozco Elena , Gonzalez‐Ros Jose M. , Garcia‐Morales Pilar , Saceda Miguel
Published: February 2003

The main goal of our study has been to analyze the efficiency of new anticancer drugs, specifically histone deacetylase inhibitors, in tumor cells bearing a multidrug resistance phenotype. We report that the histone deacetylase inhibitors, Trichostatin A and Suberoylanilide Hydroxamic Acid (SAHA), dramatically reduce cell viability and promote apoptosis in different drug‐resistant cells, affecting in a much lesser extent to their parental drug‐sensitive counterparts. The differential effects induced by Trichostatin A and SAHA between drug‐sensitive and drug‐resistant cells are reflected on the main characteristics of the resistant phenotype. Thus, reverse transcription‐PCR and Western immunoblots confirm that both histone deacetylase inhibitors promote endogenous down‐regulation of P‐glycoprotein, which is overexpressed in the drug‐resistant cells. Transfection of drug‐sensitive cells with the P‐glycoprotein cDNA ruled out the a priori possible association between apoptosis and down‐regulation of P‐glycoprotein induced by the histone deacetylase inhibitors. The results suggest a therapeutic potential of histone deacetylase inhibitors in the treatment of cancers with acquired resistance. © 2003 Wiley‐Liss, Inc.
Expression of the free β‐subunit of human chorionic gonadotropin in renal cell carcinoma: Prognostic study on tissue and serum
Authors: Hotakainen Kristina , Ljungberg Börge , Haglund Caj , Nordling Stig , Paju Annukka , Stenman Ulf‐Hakan
Published: February 2003

Expression of the free β‐subunit of human chorionic gonadotropin (hCGβ) in malignant tumors is frequently associated with aggressive disease. We have shown previously that the pretreatment serum concentration of hCGβ is an independent prognostic variable in patients with renal cell carcinoma (RCC). We now compare the serum levels with the expression of hCGβ antigen and mRNA in tumor tissue and studied whether these are associated with the clinical outcome. Serum samples were collected before surgery from patients with RCC (n = 256) and from 84 apparently healthy controls. HCGβ in serum was measured by a time‐resolved immunofluorometric assay. Tissue expression was detected by immunohistochemical staining of a tissue microarray (TMA) comprising 229 samples, and in selected cases by reverse transcription polymerase chain reaction (RT‐PCR) of hCGβ mRNA (n = 20) from tumor tissue. The prognostic value of hCGβ in serum and tissue and the association with usual clinicopathological variables was analyzed by the Kaplan‐Meier method, the log‐rank test, Cox multiple hazard regression, Mann‐Whitney U‐test or Kruskal‐Wallis test. The serum concentrations of hCGβ were increased in 27% of the RCC patients and patients with increased hCGβ levels had significantly shorter survival time than those with levels below the median (cut‐off 1.2 pmol l−1, p = 0.0044). HCGβ antigen was detected in 15% (35 of 229) of the tumors by immunohistochemistry, and hCGβ mRNA in 8 of 20 samples (40%) by RT‐PCR. Tissue positivity for hCGβ antigen was not associated significantly with mRNA expression, serum concentrations of hCGβ or survival. In multivariate analysis tumor stage, grade, size and serum hCGβ were independent prognostic variables. The serum concentration of hCGβ is an independent prognostic variable in RCC. Tissue expression of hCGβ detected by immunohistochemistry occurs in 15% of RCCs but it is not significantly associated with prognosis. Expression at the mRNA level seems to be associated with other predictors of adverse outcome. © 2003 Wiley‐Liss, Inc.
Chemical information from the source function
Authors: Gatti Carlo , Cargnoni Fausto , Bertini Luca
Published: February 2003

The source function, which enables one to equate the value of the electron density at any point within a molecule to a sum of atomic contributions, has been applied to a number of cases. The source function is a model‐independent, quantitative measure of the relative importance of an atom's or group's contribution to the density at any point in a system, and it represents a potentially interesting tool to provide chemical information. It is shown that the source contribution from H to the electron density ρbat the bond critical point in HX diatomics decreases with increasing X's electronegativity, and that this decrease is a result of significant changes in the Laplacian distribution within the H‐basin. It is also demonstrated that the source function from Li to ρbin LiX diatomics is a more sensitive index of atomic transferability than it is the lithium atomic energy or population. The observed changes are such as to ensure a constant percentage source contribution from Li to ρbthroughout the LiX series, rather than a constant source as one would expect in the limit of perfect atomic transferability. Application of the source function to planar lithium clusters has revealed that the source function clearly discriminates between a nonnuclear electron density maximum and a maximum associated to a nucleus, on the basis of the relative weight of the source contributions from the basin associated to the maximum and from the remaining basins in the cluster. The source function has also allowed for a classification of hydrogen bonds in terms of characteristic source contributions to the density at the H‐bond critical point from the H involved in the H‐bond, the H‐donor D, and the H‐acceptor A. The source contribution from the H appears as the most distinctive marker of the H‐bond strength, being highly negative for isolated H‐bonds, slightly negative for polarized assisted H‐bonds, close to zero for resonance‐assisted H‐bonds, and largely positive for charge‐assisted H‐bonds. The contributions from atoms other than H, D, and A strongly increase with decreasing H‐bond strength, consistently with the parallel increased electrostatic character of the interaction. The correspondence between the classification provided by the Electron Localization Function topologic approach and by the source function has been highlighted. It is concluded that the source function represents a practical tool to disclose the local and nonlocal character of the electron density distributions and to quantify such a locality and nonlocality in terms of a physically sound and appealing chemical partitioning. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 422–436, 2003
Electrostatic potentials and covalent radii
Authors: Politzer Peter , Murray Jane S. , Lane Pat
Published: February 2003

We begin with a brief overview of the electrostatic potentialV(r) as a fundamental determinant of the properties of systems of electrons and nuclei. The minimum ofV(r) along the internuclear axis between two bonded atoms is a natural and physically meaningful boundary point, at which the electrostatic forces of the two nuclei upon an element of charge exactly cancel. We propose that the distances from nuclei toV(r) bond minima provide the basis for a well‐defined set of covalent radii. Density functional calculations at the B3PW91/6‐311+G** level were carried out for 59 molecules to locate theV(r) minima in 95 bonds and use these as the basis for determining single‐ and multiple‐bond covalent radii for eight first‐ and second‐row atoms plus hydrogen. It was found to be unrealistic to assign a single covalent radius to each atom; different values are needed for bonds to first‐ and second‐row atoms, as well as to hydrogen. Using these results, we are able to predict the bond lengths of 33 single and multiple bonds with average errors of less than 0.04 Å relative to experimental data. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 505–511, 2003
Pasteurella multocida tenosynovitis of the hand: Sonographic findings
Authors: Triana Montserrat García , Echevarria María Antonia Fernández , Alvaro Rosa Landeras , Sagredo Pablo Sadaba , Blanco Jose Antonio Parra
Published: February 2003

Pasteurella multocida is a common cause of infection in humans subsequent to bites or scratches by dogs and, particularly, cats. This infection usually results in superficial skin and soft tissue infections. Sonography can be used for diagnosing inflammatory conditions affecting tendons, including acute and chronic tenosynovitis. P. multocida teno‐ synovitis is rare, and the diagnosis can be missed if adequate tests are not performed. We report 2 cases of P. multocida tenosynovitis of the hand and wrist in which sonography played a valuable role in assessing the affected tissues and guiding fine‐needle aspiration of fluid accumulations in the involved tendon sheaths. The diagnosis was confirmed microbiologically in each case. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:159–162, 2003
Spontaneous nontraumatic intrasplenic pseudoaneurysm: Causes, sonographic diagnosis, and prognosis
Authors: Görg Christian , Cölle Julia , Wied Mathias , Schwerk Wolf B. , Zugmaier Gerhard
Published: February 2003

Purpose

The aim of this study was to describe the incidence, causes, sonographic features, therapy, and prognosis of nontraumatic intrasplenic pseudoaneurysms (NTISPs), a rare complication of splenic infarction or infiltration by malignant systemic disorders or infectious diseases.

Methods

We retrospectively reviewed the medical and sonographic records of all patients seen at our clinic from July 1985 through December 2000 to identify patients with a sonographic diagnosis of spontaneous nontraumatic splenic rupture. We then examined the features of the resulting cases to identify patients in whom NTISPs were revealed by color Doppler sonography.

Results

In total, 41 patients were identified. Among those patients, 5 (12%) had NTISPs. Three of those 5 patients had an underlying malignant disorder (1 case of non‐Hodgkin's lymphoma and 2 cases of chronic myelogenous leukemia), and the other 2 had an inflammatory disease (1 case of endocarditis and 1 case of pancreatitis). Three of the patients also had splenic infarctions. Three patients underwent splenectomy; in 2 of them, secondary delayed splenic rupture occurred before or during splenectomy. In 2 other patients, spontaneous thrombosis of the aneurysms occurred (after 16 hours in 1 and 15 days in the other).

Conclusions

NTISPs may occur in about 12% of patients with sonographically detected nontraumatic spontaneous splenic rupture. NTISPs appear to be associated with an increased risk of secondary delayed splenic rupture, although spontaneous thrombosis may occur. Short‐term follow‐up sonographic examinations, particularly with color Doppler imaging, are recommended for early recognition of progression of NTISPs, which can guide treatment decisions. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:129–134, 2003
Sliding appendiceal inguinal hernia: Preoperative sonographic diagnosis
Authors: Çelik Ahmet , Ergün Orkan , Özbek S. Süreyya , Dökümcü Zafer , Balık Erol
Published: February 2003

We report the case of a 3‐month‐old boy with a right‐sided sliding appendiceal inguinal hernia that was diagnosed preoperatively with sonography. Surgery was performed, and intraoperative and histopathologic evaluations also revealed changes in the appendix that could have led to complications if left untreated. The infant's recovery was uneventful, and he was discharged on the second day after surgery. This condition is usually diagnosed intraoperatively, and to the best of our knowledge, this is only the second report in the English‐language medical literature in which such a case was correctly diagnosed preoperatively with sonography. In our case, the early sonographic diagnosis led to early intervention and the avoidance of potential complications. © 2003 Wiley Periodicals, Inc. J Clin Ultrasound 31:156–158, 2003
Accuracy and reproducibility of manual and semiautomated quantification of MS lesions by MRI
Authors: Ashton Edward A. , Takahashi Chihiro , Berg Michel J. , Goodman Andrew , Totterman Saara , Ekholm Sven
Published: February 2003

Purpose

To evaluate the accuracy, reproducibility, and speed of two semiautomated methods for quantifying total white matter lesion burden in multiple sclerosis (MS) patients with respect to manual tracing and to other methods presented in recent literature.

Materials and Methods

Two methods involving the use of MRI for semiautomated quantification of total lesion burden in MS patients were examined. The first method, geometrically constrained region growth (GEORG), requires user specification of lesion location. The second technique, directed multispectral segmentation (DMSS), requires only the location of a single exemplar lesion. Test data sets included both clinical MS data and MS brain phantoms.

Results

The mean processing times were 60 minutes for manual tracing, 10 minutes for region growth, and 3 minutes for directed segmentation. Intra‐ and interoperator coefficients of variation (CVs) were 5.1% and 16.5% for manual tracing, 1.4% and 2.3% for region growth, and 1.5% and 5.2% for directed segmentation. The average deviations from manual tracing were 9% for region growth and 5.7% for directed segmentation.

Conclusion

Both semiautomated methods were shown to have a significant advantage over manual tracing in terms of speed and precision. The accuracy of both methods was acceptable, given the high variability of the manual results. J. Magn. Reson. Imaging 2003;17:300–308. © 2003 Wiley‐Liss, Inc.
Breast cancer detection in gadolinium‐enhanced MR images by static region descriptors and neural networks
Authors: Tzacheva Angelina A. , Najarian Kayvan , Brockway John P.
Published: February 2003

Purpose

To automate the diagnosis of malignancy by classifying breast tissues as negative or positive for malignancy in gadolinium‐enhanced dynamic magnetic resonance (MR) images, using static region descriptors and a neural network classifier.

Materials and Methods

We propose a novel approach whereby the classifier evaluates a number of parameters that identify important tumor characteristics, as obtained by digital image processing techniques. These parameters include static signal intensity (SI) after contrast enhancement, mass margin descriptors, evaluation of mass shape by calculation of eccentricity, mass size, and mass granularity by texture analysis. Datasets for 14 patients were obtained by use of the 1.5T PMRTOW Clinical Imager.

Results

Statistical performance evaluation of the neural networks indicated 90%–100% sensitivity, 91%–100% specificity, and 91%–100% accuracy.

Conclusion

Although this work is preliminary, it may reduce overall health‐care time and costs, and enable higher accuracy in automated breast cancer detection systems. J. Magn. Reson. Imaging 2003;17:337–342. © 2003 Wiley‐Liss, Inc.
T2 quantitation of articular cartilage at 1.5 T
Authors: Maier Cynthia F. , Tan Steve G. , Hariharan Hari , Potter Hollis G.
Published: February 2003

Purpose

To evaluate sources of error when using a multiecho sequence for quantitative T2 mapping of articular cartilage at 1.5 T.

Materials and Methods

Phantom measurements were used to assess the contribution of stimulated echoes to inaccuracy of T2 measurements in cartilage using a multiecho sequence. Five volunteer studies compared in vivo single‐echo spin echo results to multiecho, single‐slice and multiecho, multislice acquisitions for assessment of both the stimulated echo and magnetization transfer contrast (MTC) contributions to T2 measurement inaccuracy.

Results

Phantom experiments demonstrated that substantial inaccuracy (10%–13% longer T2 values) is introduced from stimulated echoes with a multiecho sequence with slice‐selective refocusing pulses. The in vivo volunteer studies also demonstrated increases in measured T2 by up to 48% with a multiecho sequence. Use of the multiecho sequence in the multislice mode resulted in T2 values closer to the single‐echo standards for the volunteer studies. However, this apparent increased accuracy should be regarded as circumstantial, as it only occurs because the error due to MTC has the opposite sign compared to the error due to the stimulated echo contribution.

Conclusion

Use of a multiecho, multislice sequence for cartilage T2 measurements should be undertaken with the caution that substantial inaccuracy is introduced from stimulated echoes and MTC. J. Magn. Reson. Imaging 2003;17:358–364. © 2003 Wiley‐Liss, Inc.
Comparison of MR and PET imaging for the evaluation of liver metastases
Authors: Yang Ming , Martin Diego R. , Karabulut Nevzat , Frick Mathis P.
Published: February 2003

Purpose

To compare the accuracy of fluoro‐18‐deoxyglucose positron emission tomography (FDG‐PET) and dynamic‐enhanced magnetic resonance imaging (MRI) scans in the diagnosis of liver metastatic lesions from colon and other sources.

Materials and Methods

Thirty consecutive patients with known or suspected metastatic lesions were scanned by both MRI and PET. Histopathology and/or clinical outcome, including cross‐sectional imaging follow up, were used as a gold standard.

Results

Of 30 patients, 16 were positive by pathology and/or clinical outcome and 14 were negative for liver metastases. The sensitivity, specificity, and positive and negative predictive values on MRI were 85.7%, 100%, 100%, and 89%, respectively, compared to 71%, 93.7%, 90.9%, and 79% on FDG‐PET. The difference between the two methods was not significant (X2 = 0.2, P > 0.05).

Conclusion

Our study showed no significant difference in detection of liver metastases using MRI or FDG‐PET. However, MRI has advantages in spatial resolution and lesion characterization. J. Magn. Reson. Imaging 2003;17:343–349. © 2003 Wiley‐Liss, Inc.
Counternormative impression management, likeability, and performance ratings: the use of intimidation in an organizational setting
Authors: Bolino Mark C. , Turnley William H.
Published: February 2003

Social‐role theory suggests that women are likely to be penalized for acting assertively (or in other ways that are counter to stereotypical expectations). Using a sample of 76 supervisor–subordinate dyads, this research investigates the reactions of supervisors to the use of intimidation strategies by men and women working in a law enforcement agency. The findings suggest that, among female employees, the use of intimidation tactics of impression management is negatively related to supervisor ratings of likeability. In contrast, among males, the use of intimidation is unrelated to supervisor ratings of likeability. In addition, for females, the use of intimidation is unrelated to performance ratings; among male employees, though, the relationship between intimidation and performance evaluations is positive. The implications of this study for management practice and future research are also discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Proton transverse relaxation rate (R2) images of iron‐loaded liver tissuepping local tissue iron concentrations with MRI
Authors: Clark Paul R. , Chua‐anusorn Wanida , St. Pierre Timothy G.
Published: February 2003

Proton transverse relaxation rate (R2) imaging measurements were made on post mortem iron‐loaded human liver tissue samples (both intact and dissected into approximately 1‐cm cubes) from a single subject. Iron concentrations for the dissected samples as measured by atomic absorption spectrometry varied from 10.8 to 23.3 mg Fe.g−1 dry tissue. A significant linear correlation between the mean R2 and iron concentration of each sample was found (r = 0.95). In addition, regions of liver tissue with micronodular cirrhosis exhibited lower R2 values, corresponding to the displacement of iron by fibrotic septa. The cirrhotic tissue was clearly identified as a separate peak in the R2 distribution of the tissue. The relaxivity of the iron did not appear to depend on the microarchitecture of the tissue. Magn Reson Med 49:572–575, 2003. © 2003 Wiley‐Liss, Inc.
Multiecho sequences with variable refocusing flip angles: Optimization of signal behavior using smooth transitions between pseudo steady states (TRAPS)
Authors: Hennig Juergen , Weigel Matthias , Scheffler Klaus
Published: February 2003

A variation of the rapid acquisition with relaxation enhancement (RARE) sequence (also called turbo spin‐echo (TSE) or fast spin‐echo (FSE)) is presented. This technique uses variable flip angles along the echo train such that magnetization is initially prepared into the static pseudo steady state (PSS) for a low refocusing flip angle (α < 180°). It is shown that after such a preparation, magnetization will always stay very close to the static PSS even after significant variation of the subsequent refocusing flip angles. This allows the design of TSE sequences in which high refocusing flip angles yielding 100% of the attainable signal are applied only for the important echoes encoding for the center of k‐space. It is demonstrated that a reduction of the RF power (RFP) by a factor of 2.5–6 can be achieved without any loss in signal intensity. The contribution of stimulated‐echo pathways leads to a reduction of the effective TE by a factor ft, which for typical implementations is on the order of 0.5–0.8. This allows the use of longer echo readout times, and thus longer echo trains, for acquiring images with a given T2 contrast. Magn Reson Med 49:527–535, 2003. © 2003 Wiley‐Liss, Inc.
Mapping fiber orientation in human muscle by proton MR spectroscopic imaging
Authors: Vermathen Peter , Boesch Chris , Kreis Roland
Published: February 2003

Proton magnetic resonance spectroscopic imaging (1H‐MRSI) was used to determine muscle fiber orientations in human calf muscles. The method is based on the fact that some resonances show orientation‐dependent dipolar splitting, caused by incomplete motional averaging. This leads to proton spectra that depend strongly on the angle between muscle fibers and the magnetic field B0. The orientation‐dependent dipolar splittings were mapped using a fit with a basis set of predefined coupling patterns reflecting the fiber orientation. The fitted coupling patterns were displayed as images and assigned to different muscles based on segmented MR images. They showed gross differences in fiber orientation between some muscles, including m. soleus and m. tibialis anterior, for all subjects. In addition, smaller but significant differences between subjects were detected, which could be due to localization differences or real interindividual differences. Since dipolar splitting affects metabolite intensities, it is important to take this effect into account when calculating metabolite concentrations from MR spectra in muscle tissue. Spatial maps of the MR signals of trimethyl‐ammonium groups and creatine/ phosphocreatine revealed significant differences in intensity between muscles. Magn Reson Med 49:424–432, 2003. © 2003 Wiley‐Liss, Inc.
In vivo multiple‐mouse imaging at 1.5 T
Authors: Xu S. , Gade T.P.F. , Matei C. , Zakian K. , Alfieri A.A. , Hu X. , Holland E.C. , Soghomonian S. , Tjuvajev J. , Ballon D. , Koutcher J.A.
Published: February 2003

A multiple‐mouse solenoidal MR coil was developed for in vivo imaging of up to 13 mice simultaneously to screen for tumors on a 1.5 T clinical scanner. For the coil to be effective as a screening tool, it should permit acquisition of MRIs in which orthotopic tumors with diameters >2 mm are detectable in a reasonable period of time (<1 hr magnet time) and their sizes accurately measured. Using a spin echo sequence, we demonstrated that this coil provides sufficient sensitivity for moderately high resolution images (156–176 μm in plane‐resolution, 1.5 mm slice thickness). This spatial resolution permitted detection of primary brain tumors in transgenic/knockout mice and orthotopic xenografts. Brain tumor size as measured by MRI was correlated with size measured by histopathology (P < 0.001). Metastatic tumors in the mouse lung were also successfully imaged in a screening setting. The multiple mouse coil is simple in construction and may be implemented without any significant modification to the hardware or software on a clinical scanner. Magn Reson Med 49:551–557, 2003. © 2003 Wiley‐Liss, Inc.
Indirect 17O‐magnetic resonance imaging of cerebral blood flow in the rat
Authors: Tailor Dharmesh R. , Roy Arijit , Regatte Ravinder R. , Charagundla Sridhar R. , McLaughlin Alan C. , Leigh John S. , Reddy Ravinder
Published: February 2003

Proton T1ρ‐dispersion MRI is demonstrated for indirect, in vivo detection of 17O in the brain. This technique, which may be readily implemented on any clinical MRI scanner, is applied towards high‐resolution, quantitative mapping of cerebral blood flow (CBF) in the rat by monitoring the clearance of 17O‐enriched water. Strategies are derived and employed for 1) quantitation of absolute H217O tracer concentration from a ratio of high‐ and low‐frequency spin‐locked T1ρ images, and 2) mapping CBF without having to transform the T1ρ signal to H217O tracer concentration. Absolute regional blood flow was mapped in a single 3‐mm brain slice at an in‐plane resolution of 0.4 × 0.8 mm within a 5‐min tracer washout time; these data are consistent with the less localized CBF measurements reported in the literature. T1ρ‐weighted imaging yields excellent signal‐to‐noise ratios, spatiotemporal resolution, and anatomical contrast for mapping CBF. Magn Reson Med 49:479–487, 2003. © 2003 Wiley‐Liss, Inc.
Dynamic shim updating (DSU) for multislice signal acquisition
Authors: de Graaf Robin A. , Brown Peter B. , McIntyre Scott , Rothman Douglas L. , Nixon Terence W.
Published: February 2003

Dynamic shim updating (DSU) is a technique for achieving optimal magnetic field homogeneity over extended volumes by dynamically updating an optimal shim setting for each individual slice in a multislice acquisition protocol. Here the practical implementation of DSU using all first‐ and second‐order shims is described. In particular, the hardware modifications and software requirements are demonstrated. Furthermore, the temporal effects of dynamically switching shim currents are investigated and a Z2‐to‐Z0 compensation unit is described and implemented to counteract the temporal Z0 variations following a change in the Z2 shim current. The optimal shim settings for all slices are determined with a quantitative and user‐independent, multislice phase‐mapping sequence. The performance of DSU is evaluated from multislice phase maps and spectroscopic images acquired on rat brain in vivo. DSU improved the magnetic field homogeneity over all spatial slices, with a more pronounced effect on the slices positioned away from the magnet isocenter, thereby making the magnetic field homogeneity highly uniform over an extended volume. Magn Reson Med 49:409–416, 2003. © 2003 Wiley‐Liss, Inc.
MR molecular imaging of the Her‐2/neu receptor in breast cancer cells using targeted iron oxide nanoparticles
Authors: Artemov Dmitri , Mori Noriko , Okollie Baasil , Bhujwalla Zaver M.
Published: February 2003

MR molecular imaging is an exciting new frontier in the biomedical applications of MR. One of the clinically relevant targets is the tyrosine kinase Her‐2/neu receptor, which has a significant role in staging and treating breast cancer. In this study Her‐2/neu receptors were imaged in a panel of breast cancer cells expressing different numbers of the receptors on the cell membrane. Commercially available streptavidin‐conjugated superparamagnetic nanoparticles were used as targeted MR contrast agent. The nanoparticles were directed to receptors prelabeled with a biotinylated monoclonal antibody and generated strong T2 MR contrast in Her‐2/neu‐expressing cells. The contrast observed in MR images was proportional to the expression level of Her‐2/neu receptors determined independently with FACS analysis. In these experiments, iron oxide nanoparticles were attached to the cell surface and were not internalized into the cells, which is a major advantage for in vivo applications of the method. Magn Reson Med 49:403–408, 2003. © 2003 Wiley‐Liss, Inc.
Analysis of nets with hexagonal mesh using triangular elements
Authors: Priour Daniel
Published: February 2003

The calculation of net shapes is achieved using the finite element method. A triangular element is developed for the modelling of the net. The main hypotheses are that the strain in each triangular element is constant, that the hexagonal meshes have three directions of twine, and that the twines are elastic.

The forces due to the tension in twines are described and calculated by a direct method. The results of the model based on such triangular elements are provided. The comparison with a model where each twine is described as an elastic bar, is quite good. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of static response of structures using convex models and interval analysis method
Authors: Qiu Zhiping
Published: February 2003

In this paper, by combining the finite element analysis and non‐probabilistic convex models, we present the numerical algorithm of non‐probabilistic convex models and interval analysis method for the static displacement of structures with uncertain‐but‐bounded parameters. Under the condition of the box or interval vector determined from the ellipsoid of the uncertain‐but‐bounded structural parameter vector, by comparing the numerical algorithm of non‐probabilistic convex models and the interval analysis method in the mathematical proof and the numerical example, we can see that the width of the maximum or upper and minimum or lower bounds on the static displacement yielded by the numerical algorithm of non‐probabilistic convex models is tighter than those produced by the interval analysis method. Copyright © 2003 John Wiley & Sons, Ltd.
Recursive second order convergence method for natural frequencies and modes when using dynamic stiffness matrices
Authors: Yuan Si , Ye Kangsheng , Williams Fred W. , Kennedy David
Published: February 2003

When exact dynamic stiffness matrices are used to compute natural frequencies and vibration modes for skeletal and certain other structures, a challenging transcendental eigenvalue problem results. The present paper presents a newly developed, mathematically elegant and computationally efficient method for accurate and reliable computation of both natural frequencies and vibration modes. The method can also be applied to buckling problems. The transcendental eigenvalue problem is first reduced to a generalized linear eigenvalue problem by using Newton's method in the vicinity of an exact natural frequency identified by the Wittrick–Williams algorithm. Then the generalized linear eigenvalue problem is effectively solved by using a standard inverse iteration or subspace iteration method. The recursive use of the Newton method employing the Wittrick–Williams algorithm to guide and guard each Newton correction gives secure second order convergence on both natural frequencies and mode vectors. The second order mode accuracy is a major advantage over earlier transcendental eigenvalue solution methods, which typically give modes of much lower accuracy than that of the natural frequencies. The excellent performance of the method is demonstrated by numerical examples, including some demanding problems, e.g. with coincident natural frequencies, with rigid body motions and large‐scale structures. Copyright © 2003 John Wiley & Sons, Ltd.
A Theoretical Review of Management and Information Systems Using a Critical Communications Theory
Authors: Varey Richard J. , Wood-Harper Trevor , Wood Bob
Published: February 2003

This paper reflects on the managerialistic orthodoxy of knowledge management in order to show that a critical communications theory is required for addressing real political and ethical shortcomings. This produces an alternative methodological perspective through an intentional synthesis of established methodological views. The paper's allies in this critical quest include Jürgen Habermas, Werner Ulrich, Stanley Deetz, Geoffrey Vickers, Peter Checkland and their mentors. Information systems and knowledge systems architects and engineers and their manager clients conveniently ignore fundamental issues, including politics, power, knowledge and communication. Yet, today the more substantive issues are not technical but ethical. In raising questions about the rhetoric of knowledge management reflections on the instrumentality of much of what is said and done about management and information systems are outlined. The departure point is critical scepticism. This is motivated by concerns for the ethical status of the commercially valuable outcome of (at least) two conjoined simplistic and fundamentally dominatory conventional wisdoms. These stem from two fields that are managerialistically biased and which share a common basis in a false rationality.
The Political Lacuna in Participatory Systems Design
Authors: Saravanamuthu Kala
Published: February 2003

This paper critiques three prominent information systems (IS) contributions to the development of social (work) systems, namely ETHICS, UTOPIA and Multiple Perspectives. They are based on the socio-technical Quality of Working Life and generally rely on systems design for improving working conditions by allowing employees to appreciate a holistic work experience, instead of being treated as a cog in the profit-making machinery of capitalism. However, this paper argues that ETHICS and Multiple Perspectives in fact shy away from the ideo-political differences that cause workplace conflict in the first place. Their pluralist means of resolving workplace conflicts through discussion and negotiation fail to problematize the colonizing or hegemonic influence of economic rationalism in obscuring the feasibility of alternative modes of workplace relations. They play down the asymmetrical power relations that perpetuate the exploitation of weaker stakeholders in real-life employment negotiations. Hence, political quietism in social IS approaches fail to acknowledge the ideological causes of conflict, that is the pursuit of profit at any cost, as opposed to a more sustainable and ethical approach to workplace relations. This paper presents a study of an organizational accounting IS system and uses it for illustrating the ideological roots of differences in employee–employer needs and priorities and revealing how reflexive decision makers are alienated when they attempt to distance themselves from the myopic ethos of economic rationalism. Despite these criticisms, the paper concludes on a relatively positive note. It argues that, since the Brundtland Commission report Our Common Future was released in 1987, there has been increased awareness that organizations cannot continue to exploit our resources (and ourselves) blatantly in the name of profit maximization. This process of redefinition opens the door for more realistic and politically challenging systems approaches.
The Rationality Framework for a Critical Study of Information Systems
Authors: Cecez-Kecmanovic Dubravka , Janson Marius , Brown Ann
Published: February 2003

This paper situates the social implications of information systems (IS) within the broader context of progressive rationalization in modern organizations. Specifically, it examines the roles IS play in the rationalization of organizational processes and its social implications. The paper proposes a rationality framework that synthesizes different approaches to reason and rationality and provides a conceptual model for critical analysis of social and organizational consequences of rationalization in organizations that are enabled and supported by IS. By drawing on a field study the paper interprets three IS cases in order to demonstrate how the rationality framework helps explain different IS-organization relationships in the light of increasing levels of rationality that entail both substantial benefits and considerable risks.
Justifying Enterprise Resource Planning Adoption
Authors: Oliver Dave , Romm Celia
Published: February 2003

This paper presents a critical approach to the way organizations justify adopting enterprise resource planning (ERP) systems. An earlier critical theory provides a framework for exploring the themes of communication, rationality and domination. Technology, process and organization are forms of domination that may appear in the context of ERP adoption. The literature on the formal and informal (qualitative) justification of information technology investment is reviewed and assessed. The significance of ERP systems is examined and also motives for their adoption. The data used for the study are electronically mediated justifications of ERP adoption that were presented by universities. A content analysis is applied to these data. The paper concludes that, despite reservations about the sensitivity of domination and emancipation to identification and measurement, there is some evidence to suggest people are considered to occupy a subservient role to technology, process and organization.
The Impact of Reader Skill on Phonological processing in visual Word Recognition
Authors: Unsworth Sara J. , Pexman Penny M.
Published: February 2003

There has been much debate about the role of phonology in reading. This debate has been fuelled, in part, by mixed findings for phonological effects in lexical decision tasks. In the present research we investigated the impact of reader skill on three phonological effects (homophone, homograph, and regularity effects) in a lexical decision task and in a phonological lexical decision task. In both tasks, the more skilled readers showed different patterns of phonological effects from those of the less skilled readers; in particular, less skilled readers showed regularity effects in both tasks whereas more skilled readers did not. We concluded that more skilled readers activate phonology in these tasks but do so more efficiently, with less spurious phonological activation.
The use of Control Groups in Artificial Grammar Learning
Authors: Reber Rolf , Perruchet Pierre
Published: February 2003

Experimenters assume that participants of an experimental group have learned an artificial grammar if they classify test items with significantly higher accuracy than does a control group without training. The validity of such a comparison, however, depends on an additivity assumption: Learning is superimposed on the action of non-specific variables—for example, repetitions of letters, which modulate the performance of the experimental group and the control group to the same extent. In two experiments we were able to show that this additivity assumption does not hold. Grammaticality classifications in control groups without training (Experiments 1 and 2) depended on non-specific features. There were no such biases in the experimental groups. Control groups with training on randomized strings (Experiment 2) showed fewer biases than did control groups without training. Furthermore, we reanalysed published research and demonstrated that earlier experiments using control groups without training had produced similar biases in control group performances, bolstering the finding that using control groups without training is methodologically unsound.
Automatic Activation of Multiplication Facts: Evidence from the Nodes Adjacent to the Product
Authors: Galfano Giovanni , Rusconi Elena , Umiltà Carlo
Published: February 2003

Adult observers are widely assumed to be equipped with a specific memory store containing arithmetic facts. The present study was aimed at exploring the possibility of obtaining an automatic activation of multiplication facts by using the number-matching paradigm (LeFevre, Bisanz, & Mrkonjic, 1988), in which mental arithmetic is task irrelevant. In particular, we were interested in exploring whether the nodes that precede or follow the product node in the multiplication table can also be automatically activated as a consequence of the mere presentation of two numbers. In Experiments 1 and 2, we showed that participants were slower in responding “no“ to probes that were numbers adjacent to the product in the table related to the first operand of the initial pair than to probes that were unrelated to the initial pair. In Experiments 3 and 4, we showed a similar pattern for probes that were numbers adjacent to the product in the table related to the second operand of the initial pair. Experiments 5 and 6 ruled out alternative accounts and confirmed the results of the previous experiments. Taken together the present findings suggest that multiplication facts are stored in a highly related network in which activation spreads from the product node to adjacent nodes.
The Effect of Orthographic Uniqueness and Deviation Points on Lexical Decisions: Evidence from Unilateral and Bilateral-Redundant Presentations
Authors: Lindell Annukka K. , Nicholls Michael E.R. , Castles Anne E.
Published: February 2003

Words with an early or late orthographic uniqueness point and nonwords with an early or late orthographic deviation point were presented to the left, right, or both visual fields simultaneously. In Experiment 1, 20 participants made lexical decision judgements to horizontal stimulus presentations. In Experiment 2, a further 20 participants completed the task using vertical presentations to control for attentional biases. Consistent with previous research, words with earlier orthographic uniqueness points prompted faster responses across visual fields, regardless of stimulus orientation. Although research has suggested that the left hemisphere's superiority for language processing stems from a comparatively parallel processing strategy, with the right hemisphere reliant upon a serial mechanism, left and right visual field presentations were not differentially affected by orthographic uniqueness point. This suggests that differential sequential effects previously reported result during processes other than retrieval from the lexicon. The overall right visual field advantage observed using horizontal presentations disappeared when stimuli were presented vertically. Contrary to expectations, there was a facilitatory effect of late orthographic deviation point for horizontal nonword presentations. Overall, the results were interpreted as being consistent with predictions of a cohort model of word recognition, and they highlighted the effect of stimulus orientation on left and right hemisphere word recognition.
Semantic Effects in Word Naming: Evidence from English and Japanese Kanji
Authors: Shibahara Naoki , Zorzi Marco , Hill Martin P. , Wydell Taeko , Butterworth Brian
Published: February 2003

Three experiments investigated whether reading aloud is affected by a semantic variable, imageability. The first two experiments used English, and the third experiment used Japanese Kanji as a way of testing the generality of the findings across orthographies. The results replicated the earlier findings that readers were slower and more error prone in reading low-frequency exception words when they were low in imageability than when they were high in imageability (Strain, Patterson, & Seidenberg, 1995). This result held for both English and Kanji even when age of acquisition was taken into account as a possible confounding variable, and the imageability effect was stronger in Kanji compared to English.
Learning about Cues in their Absence: Evidence from Flavour Preferences and Aversions
Authors: Dwyer D. M.
Published: February 2003

A simple behavioural task may involve the presentation of two or more stimuli. Any learning that takes place in such a situation may be analysed in terms of the formation of an association between the central representations of those stimuli. Presumably performance based on this learning can occur because presentation of one stimulus will then activate the representations of other stimuli that were previously presented with it. To examine the role that these representations play in learning in and of themselves requires that the stimuli themselves are absent. A review of a number of flavour preference and aversion studies indicates that an associatively activated stimulus representation can support learning that is both similar to and the opposite of that maintained by the presentation of the stimulus itself. Which occurs is dependent upon the nature of the reinforcer and the temporal relationships between the training events. Although this pattern of results appears suggestive of separate learning rules, a reanalysis raises the possibility of an explanation in terms of a single associative system.
Acquisition of Knowledge about Spatial Location: Assessing the Generality of the Mechanism of Learning
Authors: Chamizo V. D.
Published: February 2003

A selection of studies in the last 20 years is reviewed. These studies show basic Pavlovian phenomena in the spatial domain (like blocking, overshadowing, latent inhibition, and perceptual learning) with nonhuman subjects, specifically with rats, both in the radial maze and in the circular pool. The generality of these phenomena with respect to other species and to other spatial preparations is also discussed. The conclusion is that the mechanism responsible for the acquisition of knowledge about spatial location seems to be associative in nature.