bluuebunny/crossref_metadata_2025 huggingface dataset:
Test‐retest reproducibility of quantitative CBF measurements using FAIR perfusion MRI and acetazolamide challenge
Authors: Yen Yi‐Fen , Field Aaron S. , Martin Eric M. , Ari Narter , Burdette Jonathan H. , Moody Dixon M. , Takahashi Atsushi M.
Published: August 2002

The reproducibility of quantitative cerebral blood flow (CBF) measurements using MRI with arterial spin labeling and acetazolamide challenge was assessed in 12 normal subjects, each undergoing the identical experimental procedure on two separate days. CBF was measured on a 1.5T scanner using a flow‐sensitive alternating inversion recovery (FAIR) pulse sequence, performed both at baseline and 12 min after intravenous administration of acetazolamide. T1 was measured in conjunction with the FAIR scan in order to calculate quantitative CBF. The CBF maps were segmented to separate gray matter (GM) from white matter (WM) for region‐of‐interest (ROI) analyses. Post‐ acetazolamide CBF values (ml/100 g/min, mean ± SD) of 87.5 ± 12.5 (GM) and 46.1 ± 10.8 (WM) represented percent increases of 37.7% ± 24.4% (GM) and 40.1% ± 24.4% (WM). Day‐to‐day differences in baseline CBF were −1.7 ± 6.9 (GM) and –1.4 ± 4.7 (WM) or, relative to the mean CBF over both days for each subject, −2.5% ± 11.7% (GM) and −3.8% ± 13.6% (WM) Day‐ to‐day differences in absolute post‐ACZ CBF increase were −2.5 ± 6.8 (GM) and 2.7 ± 9.4 (WM) or, relative to the mean CBF increase over both days for each subject, –4.7% ± 13.3% (GM) and 9.1% ± 26.2% (WM). Thus, FAIR‐ based CBF measurements show satisfactory reproducibility from day to day, but with sufficient variation to warrant caution in interpreting longitudinal data. The hemispheric asymmetry of baseline CBF and post‐acetazolamide CBF increases varied within a narrower range and should be sensitive to small changes related to disease or treatment. Magn Reson Med 47:921–928, 2002. © 2002 Wiley‐Liss, Inc.
Neuroimaging at 1.5 T and 3.0 T: Comparison of oxygenation‐sensitive magnetic resonance imaging
Authors: Krüger Gunnar , Kastrup Andreas , Glover Gary H.
Published: August 2002

Noise properties, the signal‐to‐noise ratio (SNR), contrast‐to‐noise ratio (CNR), and signal responses were compared during functional activation of the human brain at 1.5 and 3.0 T. At the higher field spiral gradient‐echo (GRE) brain images revealed an average gain in SNR of 1.7 in fully relaxed and 2.2 in images with a repetition time (TR) of 1.5 sec. The tempered gain at longer TRs reflects the fact that the physiological noise depends on the signal strength and becomes a larger fraction of the total noise at 3.0 T. Activation of the primary motor and visual cortex resulted in a 36% and 44% increase of “activated pixels” at 3.0 T, which reflects a greater sensitivity for the detection of activated gray matter at the higher field. The gain in the CNR exhibited a dependency on the underlying tissue, i.e., an increase of 1.8× in regions of particular high activation‐induced signal changes (presumably venous vessels) and of 2.2× in the average activated areas. These results demonstrate that 3.0 T provides a clear advantage over 1.5 T for neuroimaging of homogeneous brain tissue, although stronger physiological noise contributions, more complicated signal features in the proximity of strong susceptibility gradients, and changes in the intrinsic relaxation times may mediate the enhancement. Magn Reson Med 45:595–604, 2001. © 2001 Wiley‐Liss, Inc.
BISTRO: An outer‐volume suppression method that tolerates RF field inhomogeneity
Authors: Luo Y. , de Graaf R.A. , DelaBarre L. , Tannús A. , Garwood M.
Published: August 2002

A technique is described for performing frequency‐selective signal suppression with a high degree of tolerance to RF field inhomogeneity. The method is called B1‐insensitive train to obliterate signal (BISTRO). BISTRO consists of multiple amplitude‐ and frequency‐modulated (FM) pulses interleaved with spoiler gradients. BISTRO was developed for the purpose of accomplishing band‐selective signal removal, as in water suppression and outer‐volume suppression (OVS), in applications requiring the use of an inhomogeneous RF transmitter, such as a surface coil. In the present work, Bloch simulations were used to illustrate the principles and theoretical performance of BISTRO. Its performance for OVS was evaluated experimentally using MRI and spectroscopic imaging of phantoms and in vivo animal and human brain. By using FM pulses featuring offset‐independent adiabaticity, BISTRO permitted high‐quality, broadband suppression with one (or two) discrete borders demarcating the edge(s) of the suppression band. Simulations and experiments demonstrated the ability to operate BISTRO with reasonably attainable peak RF power levels and with average RF energy deposition similar to other multipulse OVS techniques. Magn Reson Med 45:1095–1102, 2001. © 2001 Wiley‐Liss, Inc.
Microstrip RF surface coil design for extremely high‐field MRI and spectroscopy
Authors: Zhang Xiaoliang , Ugurbil Kamil , Chen Wei
Published: August 2002

A new type of high‐frequency RF surface coil was developed for in vivo proton or other nuclei NMR applications at 7T. This is a purely distributed‐element and transmission line design. The coil consists of a thin strip conductor (copper or silver) and a ground plane separated by a low‐loss dielectric material with a thickness (H). Due to its specific semi‐open transmission line structure, substantial electromagnetic energy is stored in the dielectric material between the thin conductor and the ground plane, which results in a reduced radiation loss and a reduced perturbation of sample loading to the RF coil compared to conventional surface coils. The coil is characterized by a high Q factor, no RF shielding, small physical coil size, lower cost, and easy fabrication. A brief theoretical description of the microstrip RF coil is given that can be used to guide the coil designs. A set of gradient‐recalled echo images were acquired by using the single‐ and two‐turn microstrip RF surface coils from both phantom and human brain at 7T, which show good penetration and sensitivity. The two‐turn coil design significantly improves the B1 symmetry as predicted by the microstrip theory. The optimum H for microstrip surface coils is approximately 7 mm. This coil geometry yields a B1 penetration similar to that of conventional surface coils. SNR comparison was made between the microstrip coil and conventional surface coils with and without RF shielding. The results reveal that the novel surface coil design based on the microstrip concept makes very high‐field MRI/MRS more convenient and efficient in research and future clinics. Magn Reson Med 46:443–450, 2001. © 2001 Wiley‐Liss, Inc.
3D magnetization‐prepared true‐FISP: A new technique for imaging coronary arteries
Authors: Deshpande Vibhas S. , Shea Steven M. , Laub Gerhard , Simonetti Orlando P. , Finn J. Paul , Li Debiao
Published: August 2002

The purpose of this work was to develop an ECG‐triggered, segmented 3D true‐FISP (fast imaging with steady‐state precession) technique to improve the signal‐to‐noise ratio (SNR) and contrast‐to‐noise ratio (CNR) of breath‐hold coronary artery imaging. The major task was to optimize an appropriate magnetization preparation scheme to permit saturation of the epicardial fat signal. An α/2 preparation pulse was used to speed up the approach to steady‐state following a frequency‐selective fat‐saturation pulse in each heartbeat. The application of dummy cycles was found to reduce the oscillation of the magnetization during data acquisition. The fat saturation and magnetization preparation scheme was validated with simulations and phantom studies. Volunteer studies demonstrated substantially increased SNR (55%) and CNR (178%) for coronary arteries compared to FLASH (fast low‐angle shot) with the same imaging time. In conclusion, true‐FISP is a promising technique for coronary artery imaging. Magn Reson Med 46:494–502, 2001. © 2001 Wiley‐Liss, Inc.
Improved analysis of 1H‐MR spectra in the presence of mobile lipids
Authors: Auer Dorothee P. , Gössl Christoff , Schirmer Timo , Czisch Michael
Published: August 2002

Focal brain lesions can be associated with proton magnetic resonance spectra (1H‐MRS)‐detectable mobile lipids, reflecting severe tissue degradation and necrosis. However, advanced fitting procedures, such as the LCModel, fail to adequately fit spectra in the presence of lipid resonances. To overcome this, different approaches to generate lipid model spectra were compared using a phantom, real in vivo data, and simulated data. Twenty‐six in vivo short‐echo time (TE) 1H‐MRS from
21 malignant gliomas, four infections, and one ischemia were analyzed to evaluate the performance of the modified LCModel fit. Adding simulated aliphatic resonances at 1.3 and 0.9 ppm improved the overall fitting quality remarkably and allowed good separation of lactate and alanine. Also, a better differentiation of glioblastomas and anaplastic gliomas was achieved. In conclusion, we propose a simple way to efficiently include lipid resonances in the LCModel, allowing a better fit of in vivo short‐TE 1H‐MRS, and demonstrate the diagnostic potential of quantitative assessment of mobile lipids in brain tumors. Magn Reson Med 46:615–618, 2001. © 2001 Wiley‐Liss, Inc.
Novel liver macromolecular MR contrast agent with a polypropylenimine diaminobutyl dendrimer core: Comparison to the vascular MR contrast agent with the polyamidoamine dendrimer core
Authors: Kobayashi Hisataka , Kawamoto Satomi , Saga Tsuneo , Sato Noriko , Hiraga Akira , Ishimori Takayoshi , Akita Yukio , Mamede Marcelo H. , Konishi Junji , Togashi Kaori , Brechbiel Martin W.
Published: August 2002

As MRI contrast agents, more hydrophobic molecules reportedly accumulate in the liver and thus are potentially useful as liver MRI contrast agents. In this study, a generation‐4 polypropylenimine diaminobutane dendrimer (DAB‐Am64), which is expected to be more hydrophobic than the generation‐4 polyamidoamine dendrimer (PAMAM‐G4D), was used to synthesize a conjugate with 2‐(p‐isothiocyanatobenzyl)‐6‐methyl‐diethylenetriaminepentaacetic acid (1B4M) [DAB‐Am64‐(1B4M‐Gd)64] for complexing Gd(III) ions. This DAB conjugate quickly accumulated in the liver and its characteristics were studied and compared with those of a PAMAM conjugate [PAMAM‐G4D‐(1B4M‐Gd)64], which is known to be a useful vascular MRI contrast agent, in regard to its availability as a liver MRI contrast agent. DAB‐Am64‐(1B4M‐Gd)64 accumulated significantly more in the liver and less in blood than PAMAM‐G4D‐(1B4M‐Gd)64 (P < 0.001). Contrast‐enhanced MRI with DAB‐Am64‐(1B4M‐Gd)64 was able to homogeneously enhance liver parenchyma and visualize both portal and hepatic veins of 0.5 mm diameter in mice. In conclusion, DAB‐Am64‐(1B4M‐Gd)64 is a good candidate for a liver MRI contrast agent. Magn Reson Med 46:795–802, 2001. © 2001 Wiley‐Liss, Inc.
Comparison of quantitative T2 mapping and diffusion‐weighted imaging in the normal and pathologic prostate
Authors: Gibbs Peter , Tozer Daniel J. , Liney Gary P. , Turnbull Lindsay W.
Published: August 2002

In this study, diffusion‐weighted images of the human prostate were successfully obtained, enabling quantification of apparent diffusion coefficients (ADCs) in normal and pathologic regions. A dual acquisition fast spin‐echo sequence was used for accurate T2 calculation. T2 values were significantly higher in the peripheral zone than the central gland (P = 0.015). No significant correlations were found in either normal or pathologic tissue between ADC values and relaxation rates for all three gradient directions and the orientationally averaged water diffusion coefficient. Evidence suggesting that diffusional anisotropy is present in normal prostatic tissue is also detailed, with significant differences noted between the z‐component and both the x‐ and y‐components of the ADC for peripheral zone (P < 0.040) and central gland (P < 0.001). Magn Reson Med 46:1054–1058, 2001. © 2001 Wiley‐Liss, Inc.
Disease progression in amyotrophic lateral sclerosis: Predictors of survival
Authors: Magnus T. , Beck M. , Giess R. , Puls I. , Naumann M. , Toyka K.V.
Published: August 2002

Predicting the rate of disease progression has become important as trials of new medical treatments for amyotrophic lateral sclerosis (ALS) are planned. Bulbar onset, early impairment of forced vital capacity, and older age have all been associated with shorter survival. We performed a retrospective study to compare survival factors with disease progression in a German ALS population. We analyzed disease progression in 155 patients at intervals of 4 months over a period of 3 years. To evaluate disease progression, the ALS functional rating scale (ALS‐FRS), forced vital capacity (FVC%), and a Medical Research Council (MRC) compound score based on a nine‐step modified MRC scale were used. We compared age (<55 years vs. ≥55 years), different sites of disease onset (bulbar vs. limb), and gender to the rate of disease progression and performed survival analyses. No overall significant difference could be detected when analyzing these subgroups with regard to disease progression. By contrast, significantly longer survival was observed in the younger age group (56 months vs. 38 months, P < 0.0001) and in patients with limb‐onset disease (51 months vs. 37 months, P = 0.0002). Using Cox analyses values we found that the declines of ALS‐FRS, FVC%, and MRC compound score were predictive of survival (P < 0.0001, P = 0.002, and P = 0.003, respectively). Future studies are needed to clarify whether nonspecific factors including muscle atrophy, dysphagia, and coexisting diseases influence prediction of survival in ALS patients. A more precise set of predictors may help to better stratify patient subgroups for future treatment trials. © 2002 Wiley Periodicals, Inc. Muscle Nerve 25:000–000, 2002
Laser evoked potentials using the Nd:YAG laser
Authors: Lefaucheur Jean‐Pascal , Debray Sylvain , Jarry Gilbert
Published: August 2002

Pain‐related cortical potentials were evoked by skin stimulation of the face and the limbs with 5‐ns–duration laser pulses delivered by a Q‐switched Nd:YAG laser. Such laser pulses, in the nanosecond range, were able to induce pinprick pain sensations and to evoke reproducible laser evoked potentials (LEPs) without visible skin lesions for an energy density of less than 18 mJ/mm2. Low energy densities, around 10 mJ/mm2, were sufficient to reach the pain threshold and to induce LEP. The mean conduction velocity of the stimulated afferent fibers was close to 20 m/s, consistent with the stimulation of Aδ fibers. The amplitude of LEP correlated with pain perception rather than with energy density. The differences, such as wavelength and stimulus duration, between the Q‐switched Nd:YAG laser we used and the lasers that are currently used in LEP studies (i.e., CO2, argon, or Tm:YAG lasers in the millisecond range) are discussed. Our study opens novel perspectives in the LEP field of research by using a new type of laser with a very short pulse duration. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24:496–501, 2001
Impairment of voluntary control of finger motion following stroke: Role of inappropriate muscle coactivation
Authors: Kamper D.G. , Rymer W.Z.
Published: August 2002

Subjects with chronic hemiplegia following stroke attempted to perform voluntary isometric, isokinetic, and free contractions of the extensor muscles of the metacarpophalangeal (MCP) joints. We recorded torque, metacarpophalangeal joint angle and velocity, and electromyographic (EMG) activity of the extrinsic extensors and flexors and the first dorsal interosseous (FDI). We found that voluntary MCP joint extension in hemiparetic subjects was greatly impaired in comparison with control subjects: only two of the 11 stroke subjects were able to generate even 0.21 N‐m of isometric extension torque, only two could produce positive finger extension with no load, and none could develop an isokinetic concentric extension. Deficits seemed to result from a combination of coactivation of the finger flexor and extensor muscles and decreased voluntary excitation of the extensors, as normalized flexor and FDI EMG activity were greater for stroke than for control subjects (P < 0.001), but normalized extensor activity was reduced (P < 0.001). © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 673–681, 2001
Prosaposin is immunolocalized to muscle and prosaptides promote myoblast fusion and attenuate loss of muscle mass after nerve injury
Authors: Rende Mario , Brizi Emanuela , Donato Rosario , Provenzano Carlo , Bruno Rosalinda , Mizisin Andrew P. , Garrett Robert S. , Calcutt Nigel A. , Campana W. Marie , O'Brien John S.
Published: August 2002

Prosaposin is the precursor of the saposins and has both neurotrophic and myelinotrophic activity in vitro and in vivo. Using an antibody specific for the holoprotein, an immunocytochemical survey demonstrated intense staining of adult rat skeletal, cardiac, and smooth muscle cells. Prosaposin immunoreactivity in muscle appears dependent on innervation, as denervated adult rat skeletal muscles showed decreased immunostaining that returned to normal levels after reinnervation. TX14(A), a peptide derived from the neurotrophic sequence of prosaposin, attenuated the decline in muscle mass loss following nerve injury induced by a constricting ligature. In vitro, both L6 myoblasts and primary chick‐embryo myoblasts showed similar prosaposin immunopositivity, mainly in myotubes. TX14(A) induced a threefold increase in L6 myoblast fusion during early stages of differentiation without affecting cell proliferation. The fusion process was decreased in vitro in a dose‐dependent fashion by addition of a neutralizing anti‐prosaposin antibody. These data suggest that, in addition to neurotrophic and myelinotrophic activities, prosaposin has myotrophic properties. © 2001 John Wiley & Sons, Inc. Muscle Nerve 24: 799–808, 2001
Description of soil anisotropy based on multi‐laminate framework
Authors: Pietruszczak S. , Pande G. N.
Published: August 2002

In this paper, a description of inherent anisotropy of soil, based on multi‐laminate framework, is presented. The problem is formulated by assuming that the conditions at failure are governed by Coulomb criterion in which both the cohesion and the angle of internal friction are functions of the orientation of the sample. The distribution of these parameters is described by employing a set of symmetric second‐order tensors. The formulation of the problem is illustrated by some numerical examples. In particular, the directional dependence of the strength characteristics is examined for samples subjected to both plane strain and triaxial compression. Copyright © 2001 John Wiley & Sons, Ltd.
A new approach to anisotropic, bounding surface plasticity: general formulation and simulations of natural and reconstituted clay behaviour
Authors: Gajo A. , Muir Wood D.
Published: August 2002

It is demonstrated that an efficient framework for the description of a two surface kinematic hardening/bounding surface plasticity model can be devised if the model is conceived in a normalized stress space in which the bounding surface remains of constant size. The hardening of the bounding surface is contained in the transformation laws linking ‘real’ and ‘normalized’ stresses while the geometric rules controlling kinematic hardening are considered only in terms of normalized stresses.

Within the general framework thus constructed, two particular models are developed in outline. Owing to the proposed anisotropic hardening, these models are shown to have the ability to reproduce the observed characteristics of the progressive destructuration of natural cemented clays and of the plastic anisotropy of reconstituted soils. Copyright © 2001 John Wiley & Sons, Ltd.
Urge incontinence and impaired detrusor contractility in the elderly
Authors: Griffiths Derek J. , McCracken Peter N. , Harrison Gloria M. , Ann Gormley E. , Moore Katherine N.
Published: August 2002

Among the elderly, both urge incontinence and elevated residual urine are common. When they occur together, they present a challenging clinical problem, called detrusor hyperactivity with impaired contractile function (DHIC). Impaired detrusor contractility has two aspects: elevated post‐void residual urine volume and reduced detrusor contraction strength. Geriatric urge incontinence, especially in combination with reduced bladder sensation, is associated with specific cortical abnormalities: frontal and global cortical underperfusion and cognitive impairment. We have investigated, in 73 elderly incontinent patients, whether either aspect of impaired contractility is associated with urge incontinence, reduced sensation or these cortical abnormalities. For post‐void residual urine, there are no significant associations. Detrusor contraction strength, however, is significantly increased (not impaired) if there is urge incontinence, reduced bladder sensation, or cortical underperfusion. Thus, DHIC appears to be a coincidental occurrence of two common conditions with different etiological factors. Neurourol. Urodynam. 21:126–131, 2002. © 2002 Wiley‐Liss, Inc.
Bladder response to urethral flow in the awake ewe*
Authors: Robain Gilberte , Combrisson Hélène , Mazières Léonor
Published: August 2002

The flowing of fluid along the urethra can facilitate the bladder micturition contraction, a reflex appropriate to achieve complete bladder emptying. The response has been observed in animals studied in the decerebrate, spinal, or anesthetized intact state but is difficult to demonstrate in awake, healthy humans. The aim of this study was to investigate this reflex in the awake, intact state using urodynamics in the ewe. The animals were fully awake and lay gently restrained on a recording table. The bladder was catheterized, and urethral flows were obtained by slowly injecting saline at the level of the proximal urethra. Bladder and rectal pressure were monitored, and the responses to urethral flow were tested at various bladder volumes. Urethral flows consistently evoked detrusor contractions in all animals. The response started approximately 2 seconds after the beginning of the flow and largely outlasted the stimulus. Its amplitude was similar to that of the bladder‐to‐bladder micturition reflex, and, like the latter, it always required some degree of bladder filling to appear. The reflex was selectively suppressed by local anesthesia of the urethral mucosa, indicating that the effect must originate from urethral receptors. Small urethral flows thus appear to elicit large bladder micturition contractions in awake healthy animals, and the reflex could be quite significant during the normal micturition. That this reflex is found in all studied species further supports the notion that the negative results in normal awake humans are owing to descending inhibitory controls rather than to the lack of appropriate pathways. Neurourol. Urodynam. 20:641–649, 2001. © 2001 Wiley‐Liss, Inc.
Urethral instability: Clinical and urodynamic characteristics*
Authors: McLennan Mary T. , Melick Clifford , Bent Alfred E.
Published: August 2002

Filling cystometry was performed on 397 patients with lower urinary tract complaints. The overall prevalence of urethral instability was 12.6% (50/397). Of these 187 patients had detrusor instability (DI). Within the DI group, clinical and urodynamic characteristics were compared. Patients with an unstable urethra had a shorter functional urethral length (P = 0.005). For those with DI, 28 of 187 (15%) had urethral instability. Forty (21%) women had a decrease in maximal urethral pressure that preceded the detrusor contraction (type II DI). When those with type II DI were excluded, the difference in functional urethral length was not observed. Patients with type II DI experienced an earlier sensation of fullness of 228 mL compared with 283 mL for the other patients with DI (P = 0.001). There was a positive association between urethral instability and type II DI. Four different patterns of urethral pressure changes were observed. Based on these findings, it appears that a urethral abnormality may be the primary disorder in patients with type II DI. The differentiation of the various subtypes of urethral instability and DI might be important for directing therapy. Neurourol. Urodynam. 20:653–660, 2001. © 2001 Wiley‐Liss, Inc.
Bother arising from urinary frequency in women
Authors: FitzGerald M.P. , Butler N. , Shott S. , Brubaker L.
Published: August 2002

Patients commonly express bother with the symptom of frequent urination. The relationship between actual voiding frequency and this symptom is undocumented. We reviewed records of 200 women who had completed 24‐hour frequency‐volume charts, and had indicated their degree of bother with urinary frequency utilizing the short form of the Urogenital Distress Inventory. The degree of bother was correlated with daytime and nighttime voiding frequency, maximum functional capacity, mean voided volume, and demographic variables. Among 200 women, 180 (90%) indicated at least a minor degree of bother with urinary frequency. A voiding frequency of eight or more times in 24 hours was reported by 166 (83%) of women. Among the 34 women voiding fewer than eight times/24 hours, 26 (76%) reported bother with urinary frequency. There was large variation in the degree of bother reported at a given voiding frequency. Postmenopausal women without hormone replacement therapy (HRT) recorded more nighttime voids than those on HRT. Among postmenopausal women without HRT, mean voided volume and maximum functional capacity were inversely related to patient age. Our study suggests that the currently utilized cutoff value of eight daily voids to define urinary frequency, may not be helpful in the management of women in this country. A racially diverse study of the voiding habits of asymptomatic North American women is mandated. Neurourol. Urodynam. 21:36–41, 2002. © 2002 Wiley‐Liss, Inc.
Issues in flow and oxygenation dependent contrast (FLOOD) imaging of tumours
Authors: Howe F. A. , Robinson S. P. , McIntyre D. J. O. , Stubbs M. , Griffiths J. R.
Published: August 2002

The sensitivity of blood oxygenation level dependent (BOLD) contrast techniques to changes to tumour deoxyhaemoglobin concentration is of relevance to many strategies in cancer treatments. In the context of tumour studies, which frequently involve the use of agents to modify blood flow, there are underlying physiological changes different to those of BOLD in the brain. Hence we use the term, flow and oxygenation dependent (FLOOD) contrast, to emphasize this difference and the importance of flow effects. We have measured the R2* changes in a prolactinoma tumour model for a variety of vasoactive challenges [carbogen, 100% oxygen and 100% nitrogen as different breathing gases, and administration of tumour blood flow modifiers such as calcitonin gene related peptide (CGRP), hydralazine and nicotinamide]. In addition we have measured other relevant physiological parameters, such as bioenergetic status from 31P MRS, and blood pH and glucose, that may change during a vasoactive challenge. Here we discuss how they relate to our understanding of FLOOD contrast in tumours. We frequently observe R2* changes that match the expected action of the vascular stimulus: R2* decreases with agents expected to improve tumour oxygenation and blood flow, and increases with agents designed to increase tumour hypoxia. Unlike most normal tissues, tumours have a chaotic and poorly regulated blood supply, and a mix of glycolytic and oxidative metabolism; thus the response to a vasoactive challenge is not predictable. Changes in blood volume can counteract the effect of blood oxygenation changes, and changes in blood pH and glucose levels can alter oxygen extraction. This can lead to R2* changes that are smaller or the reverse of those expected. To properly interpret FLOOD contrast changes these effects must be accounted for. Copyright © 2001 John Wiley & Sons, Ltd.
Non‐invasive measurements of myocardial carbon metabolism using in vivo13C NMR spectroscopy
Authors: Ziegler André , Zaugg Christian E. , Buser Peter T. , Seelig Joachim , Künnecke Basil
Published: August 2002

Despite their prime role in maintaining contractile performance, myocardial substrate uptake, substrate preference and metabolism are difficult to assess non‐invasively. The objective of the present work was to extend the scope of cardiac 13C nuclear magnetic resonance (NMR) spectroscopy to the in vivo situation (‘closed‐chest model’) and to quantitatively appraise myocardial metabolism in vivo. For this purpose, overnight‐fasted Sprague–Dawley rats received intravenous infusions of non‐radioactive 13C‐labeled glucose, 3‐hydroxybutyrate, and acetate as markers for glycolysis, metabolism of ketone bodies and direct incorporation into tricarboxylic acid (TCA) cycle, respectively. In vivo 13C NMR spectra (at 7 T) were acquired from the myocardium with a time resolution of 6 min. At the end of the infusion experiments, tissue extracts were prepared and further analyzed by high‐resolution 13C NMR spectroscopy in order to corroborate the findings obtained in vivo. Accordingly, 3‐hydroxybutyrate and acetate were rapidly extracted by the myocardium and supplied 42 ± 6 and 53 ± 9% of the acetyl‐CoA for TCA cycle operation, whereas glucose, although also well extracted, did not contribute to myocardial oxidative metabolism. Myocardial TCA cycle turnover (VTCA) in vivo was estimated at 1.34 ± 0.07 µmol/min/g wet weight, myocardial oxygen consumption (MVO2) at 2.95 ± 0.16 µmol/min/g wet weight, exchange rate between α‐ketoglutarate and glutamate (V
x) at 1.22 ± 0.08 µmol/min/g wet weight and rate of glutamine synthesis (Vgln) at 0.14 ± 0.02 µmol/min/g wet weight. The substantial synthesis of myocardial glutamine is in contrast to experiments with isolated and saline perfused hearts. In conclusion, it is demonstrated that 13C NMR spectroscopy of the heart in intact rats is feasible and provides new quantitative insight into myocardial substrate uptake, preference and metabolism in vivo. Copyright ­© 2002 John Wiley & Sons, Ltd.
Universally maximum flow with piecewise‐constant capacities
Authors: Fleischer Lisa K.
Published: August 2002

A maximum flow over time generalizes standard maximum flow by introducing a time component. The object is to send as much flow from source to sink in T time units as possible, where capacities are interpreted as an upper bound on the rate of flow entering an arc. A related problem is the universally maximum flow, which is to send a flow from source to sink that maximizes the amount of flow arriving at the sink by time t simultaneously for all t ≤ T. We consider a further generalization of this problem that allows arc and node capacities to change over time. In particular, given a network with m arcs and n nodes, arc and node capacities that are piecewise constant functions of time with at most k breakpoints and a time bound T, we show how to compute a flow that maximizes the amount of flow reaching the sink in all time intervals (0, t] simultaneously for all 0 < t ≤ T, in O(k2mn log (kn2/m)) time. The best previous algorithm requires O(nk) maximum‐flow computations on a network with m + n)k arcs and nk nodes. Our algorithm improves on this by a factor of O(nk). © 2001 John Wiley & Sons, Inc.
Hydroxyurea‐induced partial mushroom body ablation in the honeybee Apis mellifera: Volumetric analysis and quantitative protein determination
Authors: Malun Dagmar , Plath Niels , Giurfa Martin , Moseleit Ariane D. , Müller Uli
Published: August 2002

Hydroxyurea (HU) treatment of first instar honeybee larvae was previously shown to cause mushroom body (MB) ablations. Predominantly, either one or both median MB subunits were ablated. This prompted us to analyze the effects of asymmetrical or symmetrical HU‐induced MB ablation on both the morphology of the brain and on the level of three proteins (synapsin, PKA RII, and PKC), which are considered to play a role in synaptic plasticity, learning, and memory. In brains with one median MB subunit missing the volume of the overall MB calyx neuropil in the lesioned side was diminished by 35%. This strong reduction occurred although the remaining lateral MB calyx of the lesioned brain side was found to be significantly larger than that of the intact side. Accordingly, in brains with both median MB subunits missing the size of the remaining lateral calyces increased. The various types of MB ablation differentially affected the amounts of synapsin, PKA RII, and PKC expressed in the central brain. In animals with bilateral and thus symmetrical MB ablation (both median calyces ablated) the protein amount was found to be similar to that in control animals. However, unilateral MB ablation causes an increase in the amounts of the tested proteins in the intact brain side, while the levels in the ablated side were the same as in control animals. These findings not only show that HU‐induced ablation of MB subunits is accompanied by volume changes and by changes in protein expression, but also suggest that these processes are highly regulated between the brain sides. The latter is of general importance in understanding the potential contribution of the MB subunits to learning and memory and their interaction between the brain sides. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 31–44, 2002
A neuronal inhibitory domain in the N‐terminal half of agrin
Authors: Bixby John L. , Baerwald‐De La Torre Kristine , Wang Cong , Rathjen Fritz G. , Rüegg Markus A.
Published: August 2002

Agrin is required for appropriate pre‐ and postsynaptic differentiation of neuromuscular junctions. While agrin's ability to orchestrate postsynaptic differentiation is well documented, more recent experiments have suggested that agrin is also a “stop signal” for the presynaptic neuron, and that agrin has actions on neurons in the CNS. To elucidate the neuronal activities of agrin and to define the receptor(s) responsible for these functions, we have examined adhesions of neurons and their neurite‐outgrowth responses to purified agrin in vitro. We find that both full‐length agrin and the C‐terminal 95 kDa of agrin (agrin c95), which is sufficient to induce postsynaptic differentiation, are adhesive for chick ciliary ganglion (CG) and forebrain neurons. Consistent with previous findings, our results show that N‐CAM binds to full‐length agrin, and suggest that α‐dystroglycan is a neuronal receptor for agrin c95. In neurite outgrowth assays, full‐length agrin inhibited both laminin‐ and N‐cadherin–induced neurite growth from CG neurons. The N‐terminal 150 kDa fragment of agrin, but not agrin c95, inhibited neurite outgrowth, indicating that domains in the N‐terminal portion of agrin are sufficient for this function. Adhesion assays using protein‐coated beads and agrin‐expressing cells revealed differential interactions of agrin with members of the immunoglobulin superfamily of cell adhesion molecules. However, none of these, including N‐CAM, appeared to be critical for neuronal adhesion. In summary, our results suggest that the N‐terminal half of agrin is involved in agrin's ability to inhibit neurite outgrowth. Our results further suggest that neither α‐dystroglycan nor N‐CAM, two known binding proteins for agrin, mediate this effect. © 2002 Wiley Periodicals, Inc. J Neurobiol 50: 164–179, 2002; DOI 10.1002/neu.10025
L1 mediated homophilic binding and neurite outgrowth are modulated by alternative splicing of exon 2
Authors: Jacob Jeffrey , Haspel Jeffrey , Kane‐Goldsmith Noriko , Grumet Martin
Published: August 2002

The neural cell adhesion molecule (CAM) L1 is a member of the immunoglobulin superfamily that has been implicated in neuronal adhesion, neurite outgrowth, and axon guidance. The clinical importance of L1 is illustrated by pathological mutations that lead to hydrocephalus, mental retardation, motor defects, and early mortality. The L1 gene is composed of 28 exons, including exons 2 and 27 that are spliced alternatively, and mutations in exon 2 are associated with severe neurological abnormalities in humans. To elucidate the role of L1 exon 2, a recombinant Fc fusion protein called Δ2L1 was constructed lacking the second exon in the extracellular domain of L1. When bound to fluorescent beads, L1 exhibited homophilic binding while Δ2L1 did not. However, L1 beads coaggregated with the Δ2L1 beads. Similarly, in cell binding studies, L1 bound to L1 and Δ2L1 did not bind to Δ2L1 but it bound moderately to L1. Given the reduced binding of Δ2L1, we tested its effect on neurons. By comparison to L1, a lower percentage of dissociated neurons extended neurites on Δ2L1, and there was a modest decrease in the length of the neurites that grew. Neurite outgrowth from reaggregated neurons was much less robust on Δ2L1 than on L1. The combined results indicate that Δ2L1 does not bind homophilically but it can interact with L1 containing exon 2. The reduced binding and neurite promoting activity of Δ2L1 provides an explanation for certain pathological mutations in L1 that lead to clinically apparent disease in the absence of the normal form of L1 in the nervous system. © 2002 Wiley Periodicals, Inc. J Neurobiol 51: 237–247, 2002
Transient waves in plates of functionally graded materials
Authors: Han X. , Liu G. R. , Lam K. Y.
Published: August 2002

A numerical method is proposed for analysing transient waves in plates of functionally graded material (FGM) excited by impact loads. The material properties of the FGM plate have a gradient in the thickness direction and are anisotropic in the plane of the plate. In the present method, the FGM plate is divided into layer elements in the thickness direction. For an accurate modelling of the variation of the material property of FGM plates, it is expressed by second‐order polynomials in the thickness direction within an element. This can further reduce the number of elements to obtain more accurate results effectively. The principle of virtual work is used to develop approximate dynamic equilibrium equations. The displacement response is determined by employing the Fourier transformation and the modal analysis. As examples, the displacement response of FGM plates excited by line, point and distributed loads is calculated. The computations have shown the efficiency of the present method. Copyright © 2001 John Wiley & Sons, Ltd.
Microplane finite element analysis of tube‐squash test of concrete with shear angles up to 70°
Authors: Brocca Michele , Bažant Zdeněk P.
Published: August 2002

Finite element analysis of the response of concrete structures to impact events such as missile penetration, explosive driving of anchors, blast, ground shock or seismic loading, requires knowledge of the stress–strain relations for concrete for finite strain at high pressures. A novel type of material test achieving very large shear angles of concrete at very large pressures, called the tube‐squash test, can be used to calibrate a concrete model taking into account plastic deformation at extreme pressures. A finite element analysis of such a test is performed by using a finite strain generalization of microplane models for concrete and steel. The results obtained are in good agreement with those previously obtained with a simplified method of analysis. Thus, they provide a validation of the microplane model, which is shown to be capable of reproducing the response of concrete not only for small strains at small pressures, which is predominantly brittle, but also for high pressures and large finite strains, which is predominantly frictional plastic. Copyright © 2001 John Wiley & Sons, Ltd.
A Framework for Successful E‐Technology Implementation: Understand, Simplify, Automate
Authors: Kapp Karl M.
Published: August 2002

Too many computerized systems are still not designed to best meet the business needs of their end‐users.
Often, the reason is that non‐technology managers do not take an active enough part in the design of those
systems. But those who follow the three‐step process of understanding, simplifying, and only then automating
will work most effectively with their information systems colleagues to design the most appropriate systems.
© 2001 John Wiley & Sons, Inc.
Glutamate neurotoxicity does not modify aminopeptidase activities in mouse brain homogenates
Authors: Ramírez‐Expósito María Jesús , Mayas María Dolores , García María Jesús , Ramírez Manuel , Martínez‐Martos José Manuel
Published: August 2002

Glutamate is the principal excitatory neurotransmitter in the brain, playing an important role in several physiological neuronal activities. When excessive glutamate is released, a cascade of events causes the formation of free radicals. The central nervous system is particularly vulnerable to free radical damage, due to free radicals induce membrane lipids peroxidation. Aminopeptidases are enzymes implicated in the regulation of several biologically active peptides. In the present study, we have investigated if glutamate excitotoxicity, under conditions that induce lipid peroxidation, lead to aminopeptidases misregulation. We conclude that aminopeptidase activities are not altered by the characteristic neurodegeneration and excitotoxicity associated with glutamate.
Healed trauma in an early Bronze Age human skeleton from Buckinghamshire, England
Authors: Anderson T.
Published: August 2002

An adult male from a multiple burial at the centre of an early Bronze Age barrow displays a healed fracture of the tibial condyle. Apparently, this is the first reported evidence for this type of fracture in British archaeological material. It provides evidence for care and compassion in the prehistoric period. Also, it apparently indicates that high social status could be retained by an individual who was suffering from a physical incapacity. Copyright © 2002 John Wiley & Sons, Ltd.
Impact of compulsory competitive tendering on the structure and performance of local government systems in the State of Victoria*
Authors: Alam Quamrul , Pacher John
Published: August 2002

Around the world, the public sector is introducing private sector management practices. Abandoning the binary model of public and private sectors the State Government of Victoria introduced the compulsory competitive tendering system under which local government bodies are required to tender out their services to private sector service providers. The aim was to encourage local government bodies to operate in contestable situations so that they can increase efficiency, decrease operating costs, develop clear programme goals and objectives, become responsive to client goals, and improve the quality of goods and services. The article describes how the practice of the compulsory competitive tendering system has introduced major changes to organizational cultures, attitudes of employees, power and authority structures, sytems of decision making, delegation of financial and managerial authority, and the nature of control and accountability. In addition, the article explains the degree of competitiveness and efficiency that local government bodies have achieved and describes how the corporatized structure has helped to achieve the financial objectives. The article also discusses how the role of the elected councils is diminishing under this new management structure and argues that in the absence of a genuine monitoring system and accountability mechanism the local government bodies find it difficult to assert their role as quality service deliverers. This has forced the councils to comply with the requirements of the competition laws which have reduced direct accountability of government to the public. Copyright © 2000 John Wiley & Sons, Ltd.
A concept for bifocal contact‐ or intraocular lenses: liquid single crystal hydrogels (“LSCH”)
Authors: Amigó‐Melchior Agustín , Finkelmann Heino
Published: August 2002

The synthesis of liquid single crystal hydrogels (“LSCH”) in suitable molds offers an innovative concept to realize bifocal contact‐ or intraocular‐lenses. LSCH combine the properties required for applications as bifocal ophthalmic lenses: the soft and water‐containing hydrogel enables oxygen permeation and exhibits high birefringence due to the liquid crystalline phase structure built up by rigid rod‐like amphiphiles. Via a photo‐initiated crosslinking reaction of aqueous solutions of monomeric lyotropic liquid crystalline amphiphiles in the macroscopically ordered liquid crystalline state, we obtain optically uniaxially ordered and transparent LSCH. The orientation process and the phase structure of the anisotropic hydrogel is analyzed by deuterium NMR‐spectroscopy. Copyright © 2002 John Wiley & Sons, Ltd.
Surface modification of inorganic oxide particles with silane coupling agent and organic dyes
Authors: Lin Jun , Siddiqui Junaid A. , Ottenbrite Raphael M.
Published: August 2002

The silane coupling agent 3‐glycidoxypropyl trimethoxylsilane (GPS) was grafted onto the surface of silica gel, P
2 glass beads and TiO
2 oxide particles. FT‐IR, thermogravimetric and elemental analysis were used to characterize the modified particles. The effects of various factors on the GPS grafting efficiency such as catalyst, GPS concentration, reaction temperature and time were studied. After modification with GPS, the xanthene dye rhodamine B and azo dyes 4‐phenylazophenol and 4‐phenylazoaniline, respectively, were grafted on to the particles, which were then used as pigment fillers. The colors of the pigments were adjusted by changing the kind of dyes, the concentration, the pH and the reaction solvents. Copyright © 2001 John Wiley & Sons, Ltd.
Assessment of a simple, non‐toxic alamar blue cell survival assay to monitor tomato cell viability
Authors: Byth Heather‐Anne , Mchunu Bongani I. , Dubery Ian A. , Bornman Liza
Published: August 2002

The Alamar Blue (AB) assay, which incorporates a redox indicator that changes colour or fluorescence in response to metabolic activity, is commonly used to assess quantitatively the viability and/or proliferation of mammalian cells and micro‐organisms. In this study the AB assay was adapted for the determination of the viability of plant cells. Cell suspension cultures of tomato, Lycopersicon esculentum, L., with differing viabilities, served as the experimental model for a comparison of the AB assay with the conventional 2,3,5‐triphenyltetrazolium chloride (TTC) viability assay. The AB assay showed a sigmoidal relationship between cell viability and AB reduction (as quantified by spectrofluorometry or spectrophotometry), which was similar to that obtained using the TTC assay. Both assays detected a significant reduction in cell viability after 48 h exposure to virulent Ralstonia solanacearum (biovar III), while the TTC assay, in addition, revealed cell proliferation in control cells from 24 to 72 h. The TTC assay detected cell proliferation over a wider range of cell densities, while the AB assay was more rapid and versatile whilst being non‐toxic and thus allowing subsequent cell analysis. Copyright © 2001 John Wiley & Sons, Ltd.
Quantitative determination of cytotoxic­Friedo‐nor‐oleanane derivatives from five morphological types of Maytenus ilicifolia (celastraceae) by reverse‐phase high‐performance liquid chromatography
Authors: Filho Waldemar Buffa , Corsino Joaquim , Bolzani Vanderlan da Silva , Furlan Maysa , Pereira Ana Maria S. , França Suzelei Castro
Published: August 2002

Five different morphological types of Maytenus ilicifolia of the same age and harvested under the same conditions showed distinct accumulations of some friedo‐nor‐oleananes. A rapid, sensitive and reliable reverse‐phase HPLC method (employing an external standard) was used for the determination of the cytotoxic triterpenoids, 20α‐hydroxymaytenin, 22β‐hydroxymaytenin, maytenin, celastrol and pristimerin in each of the five types. Well resolved peaks with good detection response and linearity in the range­1.0–100 µg/mL were obtained. Copyright © 2002 John Wiley & Sons, Ltd.