bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitation of differential renal blood flow and renal function using dynamic contrast‐enhanced MRI in rats
Authors: Pedersen Michael , Shi Yimin , Anderson Peter , Stødkilde‐Jørgensen Hans , Christian Djurhuus Jens , Gordon Isky , Frøkiær Jørgen
Published: February 2004

A first‐pass upslope approach was used to estimate differential renal blood flow (DRBF) and a Patlak‐Rutland approach was used to estimate differential renal function (DRF) using Gd‐DTPA‐BMA‐enhanced MRI. DRBF and DRF were estimated in rat kidneys under three different experimental conditions: 1) transient renal artery occlusion (TRAO); 2) partial unilateral ureteric obstruction (PUO); and 3) sham‐operated control rats (SHAM). A bolus of Gd‐DTPA‐BMA was given intravenously during a dynamic single slice T1‐weighted gradient echo sequence, which allowed calculation of concentration from signal intensity values. Calculations based on the raw signal intensity showed that DRBF was decreased in both PUO (44 ± 1%; P < 0.05) and in TRAO (38 ± 1%; P < 0.05) compared with SHAM (52 ± 1%). Converting the signal intensity into a measure of Gd‐DTPA‐BMA concentration did not substantially alter these findings (PUO: 40 ± 3%, P < 0.05; TRAO: 35 ± 2%, P < 0.05; SHAM 49 ± 1%). Likewise, DRF decreased in both PUO (43 ± 4%; P < 0.05) and TRAO (39 ± 3%; P < 0.05) compared with SHAM (48 ± 2%). Converting the signal intensity into measurements of Gd‐DTPA‐BMA concentration revealed similar findings (PUO: 41 ± 5%, P < 0.05; TRAO: 34 ± 5%, P < 0.05; SHAM: 49 ± 2%). Our results suggest that renal damage in rats may be demonstrated by an observed reduction of DRBF and DRF as estimated from single‐slice Gd‐DTPA‐BMA enhanced signal intensity using time–activity curves with and without quantitation of Gd‐concentration. Magn Reson Med 51:510–517, 2004. © 2004 Wiley‐Liss, Inc.
Parallel imaging reconstruction using automatic regularization
Authors: Lin Fa‐Hsuan , Kwong Kenneth K. , Belliveau John W. , Wald Lawrence L.
Published: February 2004

Increased spatiotemporal resolution in MRI can be achieved by the use of parallel acquisition strategies, which simultaneously sample reduced k‐space data using the information from multiple receivers to reconstruct full‐FOV images. The price for the increased spatiotemporal resolution in parallel MRI is the degradation of the signal‐to‐noise ratio (SNR) in the final reconstructed images. Part of the SNR reduction results when the spatially correlated nature of the information from the multiple receivers destabilizes the matrix inversion used in the reconstruction of the full‐FOV image. In this work, a reconstruction algorithm based on Tikhonov regularization is presented that reduces the SNR loss due to geometric correlations in the spatial information from the array coil elements. Reference scans are utilized as a priori information about the final reconstructed image to provide regularized estimates for the reconstruction using the L‐curve technique. This automatic regularization method reduces the average g‐factors in phantom images from a two‐channel array from 1.47 to 0.80 in twofold sensitivity encoding (SENSE) acceleration. In vivo anatomical images from an eight‐channel system show an averaged g‐factor reduction of 1.22 to 0.84 in 2.67‐fold acceleration. Magn Reson Med 51:559–567, 2004. © 2004 Wiley‐Liss, Inc.
Cortical depth‐dependent gradient‐echo and spin‐echo BOLD fMRI at 9.4T
Authors: Zhao Fuqiang , Wang Ping , Kim Seong‐Gi
Published: February 2004

To examine cortical depth‐related spatial specificity and signal changes in gradient‐echo (GE) and spin‐echo (SE) blood oxygenation level‐dependent (BOLD) fMRI signals, a well‐established cat visual stimulation model was used at 9.4T. The GE BOLD signal percent change is the highest at the surface of the cortex containing pial vessels, and decreases as cortical depth increases. In contrast, the SE BOLD signal is more specific to parenchyma, showing the highest signal change in the middle cortical areas. The stimulation‐induced ΔR to ΔR2 ratio is dependent on the vessel size, which is related to basal susceptibility effects. The averaged ratio of ΔR to ΔR2 in all active regions, including large vessels, is 3.3 ± 0.5 (N = 6). The averaged ratio of ΔR to ΔR2 is 8.8 ± 1.7 (N = 4) on the surface of the cortex with large pial draining vessels, and decreases to 1.9 ± 0.1 on the middle cortical areas with parenchymal microvessels. ΔR/ΔR2 is closely related to basal susceptibility effects and can be used to differentiate tissue from vessel regions. Magn Reson Med 51:518–524, 2004. © 2004 Wiley‐Liss, Inc.
Reference‐scan‐free method for automated correction of nyquist ghost artifacts in echoplanar brain images
Authors: Zhang Yan , Wehrli Felix W.
Published: February 2004

One of the most common artifacts for echo‐planar imaging is the Nyquist ghost, typically overcome with the aid of a reference scan preceding the actual image acquisition. In this work, a nonlinear phase correction obviating the need for a reference scan is proposed. The method is based on computing the second moments of the even and odd subdomains of the phase‐encoding k‐space data to retrieve the phase disparities between even and odd echoes. The method's underlying assumption is that the images are dominated by their low frequency and symmetric part. In vivo data demonstrate the effectiveness of the algorithm showing ghost suppression comparable to that achievable with the reference‐scan method. Magn Reson Med 51:621–624, 2004. © 2004 Wiley‐Liss, Inc.
Noninvasive in vivo determination of intracerebral oxygen concentration in rats by a longitudinally detected ESR (LODESR) technique
Authors: Yokoyama Hidekatsu , Sato Toshiyuki , Fukui Kouichi , Itoh Osamu , Ohya Hiroaki , Akatsuka Takao
Published: February 2004

We have developed a noninvasive method to determine oxygen concentration in the brain tissue of rats in vivo. The method is based upon measuring the fundamental harmonic‐to‐secondary harmonic ratio (FSR) of longitudinal magnetization changes of a blood–brain barrier (BBB)‐permeable nitroxide radical, 3‐hydroxymethyl‐2,2,5,5‐tetramethylpyrrolidine‐1‐oxyl (hydroxymethyl‐PROXYL), by employing a longitudinally detected ESR (LODESR) spectrometer operating at an ESR frequency of 280 MHz. FSRs of phantoms, including a hydroxymethyl‐PROXYL solution and various concentrations of oxygen, were measured. We found that the FSRs of the phantom increased as the oxygen concentration increased. In vivo FSRs in the brains of rats that had received a hydroxymethyl‐PROXYL injection were measured without the use of any surgical procedures. It was found that when the rats breathed 100% oxygen, rather than normal air, the FSR was significantly greater. Magn Reson Med 51:595–601, 2004. © 2004 Wiley‐Liss, Inc.
Novel system for determining contrast agent concentration in mouse blood in vivo
Authors: Pathak Arvind P. , Artemov Dmitri , Bhujwalla Zaver M.
Published: February 2004

A method for measuring contrast agent concentration in blood was developed using a switchable RF tail coil to obtain MR signal from the mouse tail vein. The switchable RF coil was used to obtain quantitative high‐resolution T1 maps of the tail in combination with a second coil used to obtain images from regions of interest in a mouse tumor model. The effect of flow rates on the T1 measurements was validated using a flow‐phantom. Reliable estimates of blood T1 were obtained for flow rates up to 0.5 cm/sec in SCID mice. There was no significant difference between the in vivo tail coil measurements and in vitro blood sample relaxation rates of blood. The ability to measure the concentration of contrast agents in mouse blood in vivo is useful for several applications, such as obtaining quantitative values of tumor vascular volume and permeability, determining the effectiveness of drug delivery to tumors, or for detecting lymphatic drain. Magn Reson Med 51:612–615, 2004. © 2004 Wiley‐Liss, Inc.
Detection of amyloid plaques in mouse models of Alzheimer's disease by magnetic resonance imaging
Authors: Zhang Jiangyang , Yarowsky Paul , Gordon Marcia N. , Di Carlo Giovanni , Munireddy Sanjay , van Zijl Peter C.M. , Mori Susumu
Published: February 2004

We performed three‐dimensional, high‐resolution magnetic resonance imaging (MRI) of fixed mouse brains to determine whether MRI can detect amyloid plaques in transgenic mouse models of Alzheimer's disease. Plaque‐like structures in the cortex and hippocampus could be clearly identified in T2‐weighted images with an image resolution of 46 μm × 72 μm × 72 μm. The locations of plaques were confirmed in coregistration studies comparing MR images with Congo red‐stained histological results. This technique is quantitative, less labor‐intensive compared to histology, and is free from artifacts related to sectioning process (deformation and missing tissues). It enabled us to study the distribution of plaques in the entire brain in 3D. The results of this study suggest that this method may be useful for assessing treatment efficacy in mouse models of Alzheimer's disease (AD). Magn Reson Med 51:452–457, 2004. © 2004 Wiley‐Liss, Inc.
Quantification of tumor tissue populations by multispectral analysis
Authors: Carano Richard A.D. , Ross Adrienne L. , Ross Jed , Williams Simon P. , Koeppen Hartmut , Schwall Ralph H. , Van Bruggen Nicholas
Published: February 2004

Tumor heterogeneity complicates the quantification of a therapeutic response by MRI. To address this issue, a novel approach has been developed that combines MR diffusion imaging with multispectral (MS) analysis to quantify tumor tissue populations. K‐means (KM) clustering of the apparent diffusion coefficient (ADC), T2, and proton density (M0) was employed to estimate the volumes of viable tumor tissue, necrosis, and neighboring subcutaneous adipose tissue in a human colorectal tumor xenograft mouse model. In a second set of experiments, the temporal evolution of the MS tissue classes in response to therapeutic intervention Apo2L/TRAIL and CPT‐11 was observed. The multiple parameters played complementary roles in identifying the various tissues. The ADC was the dominant parameter for identifying regions of necrosis, whereas T2 identified two necrotic subpopulations, and M0 contributed to the differentiation of viable tumor from subcutaneous adipose tissue. MS viable tumor estimates (mean volume = 275 ± 147 mm3) were highly correlated (r = 0.81, P < 0.01) with histological estimates (117 ± 51 mm3). In the treatment study, MS viable tumor volume (at day 10) was 77 ± 67 mm3 for the Apo2L/TRAIL+CPT‐11 group, and was significantly reduced relative to the control group (292 ± 127 mm3, P < 0.01). This method shows promise as a means of detecting an early therapeutic response in vivo. Magn Reson Med 51:542–551, 2004. © 2004 Wiley‐Liss, Inc.
A pneumatic vibrotactile stimulation device for fMRI
Authors: Briggs Richard W. , Dy‐Liacco Iona , Malcolm Matthew P. , Lee Hyunsook , Peck Kyung K. , Gopinath Kaundinya S. , Himes Nathan C. , Soltysik David A. , Browne Paul , Tran‐Son‐Tay Roger
Published: February 2004

Mapping the functional response of the somatosensory cortex is useful both for characterizing normal brain activity and for determining the functional integrity of damaged cortex compromised by stroke or other neurological insults. A variety of stimulators have been used to produce somatosensory cortex activation in functional brain imaging, including brushes and swabs operated manually, pneumatically and mechanically powered mechanical vibrators, air puffs, and vibrating ceramic piezoelectric wafers and benders. A closed‐system, pneumatically driven rubber diaphragm is reported that overcomes many of the limitations of existing vibrotactile devices and produces robust sensory cortex activation in an fMRI experiment. Magn Reson Med 51:640–643, 2004. © 2004 Wiley‐Liss, Inc.
Fast, pseudo‐continuous arterial spin labeling for functional imaging using a two‐coil system
Authors: Hernandez‐Garcia Luis , Lee Gregory R. , Vazquez Alberto L. , Noll Douglas C.
Published: February 2004

A fast, two‐coil, pseudo‐continuous labeling scheme is presented. This new scheme permits the collection of a multislice subtraction pair in <3 s, depending on the subject's arterial transit times. The method consists of acquiring both control and tag images immediately after a labeling period that matches the arterial transit time. The theoretical basis of the technique, and simulations of the signal during changes in both transit time and perfusion are presented. Experimental data from functional imaging experiments were collected to demonstrate the technique and its characteristics. Magn Reson Med 51:577–585, 2004. © 2004 Wiley‐Liss, Inc.
Optimized precision of inversion‐recovery T1 measurements for constrained scan time
Authors: Ogg Robert J. , Kingsley Peter B.
Published: February 2004

Optimization of inversion‐recovery (IR) measurements of T1 relaxation times has focused on the efficiency of T1 estimation (precision per unit time), without explicit consideration of the total experimental time. With the modified fast IR method, the repetition time (TR) is constant and each inversion time (TI) must be less than TR. For a fixed total experimental time in the absence of signal averaging, TR and the longest TI time must decrease as more TI times are added. This article investigates the number of TI times and their values to optimize the precision of T1 measurements when time constraints preclude signal averaging and limit the largest TI that can be acquired. If the longest TI is less than approximately three times the longest T1 of interest, then precision is optimum with only four TI times. Suggestions are given for selecting the optimum TI times for 1–16‐fold ranges of T1 times relative to a given maximum T1. Magn Reson Med 51:625–630, 2004. © 2004 Wiley‐Liss, Inc.
Mimicking liver iron overload using liposomal ferritin preparations
Authors: Wood John C. , Fassler Joe D. , Meade Tom
Published: February 2004

Close monitoring of liver iron content is necessary to prevent iron overload in transfusion‐dependent anemias. Liver biopsy remains the gold standard; however, MRI potentially offers a noninvasive alternative. Iron metabolism and storage is complicated and tissue/disease‐specific. This report demonstrates that iron distribution may be more important than iron speciation with respect to MRI signal changes. Simple synthetic analogs of hepatic lysosomes were constructed from noncovalent attachment of horse‐spleen ferritin to 0.4 μm diameter phospholipid liposomes suspended in agarose. Graded iron loading was achieved by varying ferritin burden per liposome as well as liposomal volume fraction. T1 and T2 relaxation times were measured on a 60 MHz NMR spectrometer and compared to simple ferritin‐gel combinations. Liposomal‐ferritin had 6‐fold stronger T2 relaxivity than unaggregated ferritin but identical T1 relaxivity. Liposomal‐ferritin T2 relaxivity also more closely matched published results from hemosiderotic marmoset liver, suggesting a potential role as an iron‐calibration phantom. Magn Reson Med 51:607–611, 2004. © 2004 Wiley‐Liss, Inc.
New model for analysis of dynamic contrast‐enhanced MRI data distinguishes metastatic from nonmetastatic transplanted rodent prostate tumors
Authors: Fan Xiaobing , Medved Milica , River Jonathan N. , Zamora Marta , Corot Claire , Robert Philippe , Bourrinet Philippe , Lipton Martin , Culp Rita M. , Karczmar Gregory S.
Published: February 2004

Dynamic contrast‐enhanced MRI (DCEMRI) data were acquired from metastatic and nonmetastatic tumors in rodents to follow the uptake and washout of a low‐molecular‐weight contrast agent (Gd‐DTPA) and a contrast agent with higher molecular weight (P792). The concentration vs. time curves calculated for the tumor rims and centers were analyzed using the two‐compartment model (TCM) and a newly developed empirical mathematical model (EMM). The EMM provided improved fits to the experimental data compared to the TCM. Parameters derived from the empirical model showed that the contrast agent washout rate was significantly slower in metastatic tumors than in nonmetastatic tumors for both Gd‐DTPA (P < 0.03) and P792 (P < 0.04). The effects of the tumor on blood flow in “normal” tissue immediately adjacent to the tumors were evident: Gd‐DTPA uptake and washout rates were much lower in muscle near the tumor (P < 0.05) than normal muscle farther from the tumor. The results suggest that accurate fits of DCEMRI data provide kinetic parameters that distinguish between metastatic and relatively benign cancers. In addition, a comparison of the dynamics of Gd‐DTPA and P792 provides information regarding the microenvironment of tumors. Magn Reson Med 51:487–494, 2004. © 2004 Wiley‐Liss, Inc.
Single TrAjectory Radial (STAR) imaging
Authors: Sarty Gordon E.
Published: February 2004

The number of MRI applications that use radial k‐space data acquisition have been increasing because of their inherent robustness to motion‐induced reconstruction image artifacts relative to Cartesian acquisition methods. However, images reconstructed from radial data are more prone to image degrading effects due to magnetic field inhomogeneities than images made from Cartesian data. Presented here is a method for acquiring several radial k‐space data lines in one trajectory, the Single TrAjectory Radial, or STAR method, that is a variation of radial EPI. The STAR method allows for angular oversampling without the increase in imaging time that occurs with angularly oversampled single line imaging. It is shown that such oversampling potentially reduces the image degrading effect of magnetic field inhomogeneities so that the motion robust features of radial imaging may be realized in a segmented EPI approach. Magn Reson Med 51:445–451, 2004. © 2004 Wiley‐Liss, Inc.
Spiral readout gradients for the reduction of motion artifacts in chemical shift imaging
Authors: Kim Dong‐Hyun , Adalsteinsson Elfar , Spielman Daniel M.
Published: February 2004

A motion artifact reduction method for proton chemical shift imaging (CSI) is presented. The method uses spiral‐based readout gradients for data acquisition. A characteristic of spiral‐based readout gradients is that data are repeatedly sampled at the kxy origin. These data points are used to estimate and correct for motion‐induced phase variations. Both phantom and in vivo spectra reconstructed using the new motion artifact reduction algorithm showed significant signal‐to‐noise ratio (SNR) improvements as compared to uncorrected data. Magn Reson Med 51:458–463, 2004. © 2004 Wiley‐Liss, Inc.
Removing the effect of SVD algorithmic artifacts present in quantitative MR perfusion studies
Authors: Smith M.R. , Lu H. , Trochet S. , Frayne R.
Published: February 2004

Quantitative cerebral blood flow (CBF) values can be obtained from dynamic susceptibility contrast (DSC) MR perfusion studies using the standard singular value decomposition (sSVD) deconvolution algorithm. Reports in the literature from simulation and in vivo studies suggest that CBF estimates obtained using sSVD deconvolution depend on the arterial‐tissue delay (ATD). By contrast, Fourier transform (FT) deconvolution produces CBF estimates that are independent of ATD. The diagnostic reliability of quantitative CBF measurements to define areas of normal tissue flow and tissue at risk is brought into doubt by such gross sensitivity to the specifics of the deconvolution approach. This variation of CBF values with ATD is shown to be an artifact associated with the current implementation of the sSVD deconvolution algorithm. A reformulated version of the SVD deconvolution algorithm (rSVD) is presented and compared to the standard SVD algorithm through simulation and patient case studies. Magn Reson Med 51:631–634, 2004. © 2004 Wiley‐Liss, Inc.
Measurement of brain glutamate using TE‐averaged PRESS at 3T
Authors: Hurd Ralph , Sailasuta Napapon , Srinivasan Radhika , Vigneron Daniel B. , Pelletier Daniel , Nelson Sarah J.
Published: February 2004

A method is introduced that provides improved in vivo spectroscopic measurements of glutamate (Glu), glutamine (Gln), choline (Cho), creatine (Cre), N‐acetyl compounds (NAtot, NAA + NAAG), and the inositols (mI and sI). It was found that at 3T, TE averaging, the f1 = 0 slice of a 2D J‐resolved spectrum, yielded unobstructed signals for Glu, Glu + Gln (Glx), mI, NAtot, Cre, and Cho. The C4 protons of Glu at 2.35 ppm, and the C2 protons of Glx at 3.75 ppm were well resolved and yielded reliable measures of Glu/Gln stasis. Apparent T1/T2 values were obtained from the raw data, and metabolite tissue levels were determined relative to a readily available standard. A repeatibility error of <5%, and a coefficient of variation (CV) of <10% were observed for brain Glu levels in a study of six normal volunteers. Magn Reson Med 51:435–440, 2004. © 2004 Wiley‐Liss, Inc.
Decreased cerebral perfusion correlates with increased BOLD hyperoxia response in transgenic mouse models of sickle cell disease
Authors: Kennan Richard P. , Suzuka Sandra M. , Nagel Ronald L. , Fabry Mary E.
Published: February 2004

Neurological complications such as stroke are known consequences of sickle cell disease (SCD). In order to improve methods for the evaluation of stroke risk in SCD, MRI was used to evaluate cerebrovascular function in transgenic mouse models of human SCD. It is hypothesized that oxygen‐sensitive imaging in the brain will reveal areas of excess deoxygenation that are either at risk of or the result of vaso‐occlusion. Arterial spin labeling (ASL) perfusion was performed in order to correlate BOLD results with microvascular cerebral blood flow. Upon comparison with control animals, there was a relative increase in BOLD hyperoxia response of 42–67% (P < 0.001) in the transgenic mice while cerebral blood flow during normoxia was reduced by 30–40% (P < 0.02). Hyperoxia caused cerebral blood flow to decrease in control mice, whereas blood flow increased in the sickle transgenic mice. These results indicate impairment in brain autoregulation in the sickle cell transgenic mice leading to increased cerebral deoxyhemoglobin. Increased deoxyhemoglobin coupled with reduced perfusion may further increase the risk of vaso‐occlusion and stroke. This may reflect polymer reduction or reduced cell adhesion during hyperoxia. The MRI protocol is noninvasive and thus directly applicable to a clinical population. Magn Reson Med 51:525–532, 2004. © 2004 Wiley‐Liss, Inc.
In vivo assessment of tumoral angiogenesis
Authors: Troprès I. , Lamalle L. , Péoc'h M. , Farion R. , Usson Y. , Décorps M. , Rémy C.
Published: February 2004

Vessel size imaging (VSI) for brain tumor characterization was evaluated and the vessel size index measured by MRI (VSIMRI) was correlated with VSI obtained by histology (VSIhisto). Blood volume (BV) and VSI maps were obtained on 12 rats by simultaneous measurements of R2* and R2, before and after the injection of a macromolecular contrast agent, AMI‐227. Immunostaining of collagen IV in vessels was performed. An expression was derived for evaluating VSI from stereologic measurements on histology data (VSIhisto). On BV and VSI images obtained from large‐size tumors (n = 9), three regions could be distinguished and correlated well with histological sections: a high BV region surrounding the tumor, a necrotic area where BV is very low, and a viable tumor tissue region showing lower BV but higher VSI than the normal rat cortex, with the presence of larger vessels. The quantitative analysis showed a good correlation (Spearman rank's rho = 0.74) between VSIhisto and VSIMRI with a linear regression coefficient of 1.17. The good correlation coefficient supports VSI imaging as a quantitative method for tumor vasculature characterization. Magn Reson Med 51:533–541, 2004. © 2004 Wiley‐Liss, Inc.
Accentuation of high susceptibility of hypertrophied myocardium to ischemia: Complementary assessment of Gadophrin‐enhancement and left ventricular function with MRI
Authors: Schalla Simon , Wendland Michael F. , Higgins Charles B. , Ebert Wolfgang , Saeed Maythem
Published: February 2004

The aim of the study was to compare infarction size and left ventricular (LV) function in normal and hypertrophied hearts after brief ischemia using Gadophrin‐enhancement and functional assessment by MRI. Rats (n = 20) were assigned to aortic banding to induce LV hypertrophy or control. Eight weeks later, rats were subjected to 25 min of regional myocardial ischemia followed by 3 hr of reperfusion. The necrosis‐specific agent Gadophrin‐3 was injected to delineate infarcted myocardium on MRI. Effects of aortic banding and ischemia on LV mass and function were determined. At postmortem, areas at risk and infarction were measured. Close correlation was found between LV mass measured with MRI and at postmortem (r = 0.98). LV mass measured with MRI was significantly greater (0.81 ± 0.02 g) in animals with aortic banding compared to control (0.62 ± 0.02 g; P < 0.001). Infarction size was larger in hypertrophied hearts (19.0 ± 1.4% / 18.3 ± 1.5%) than in control (9.8 ± 1.7% / 9.2 ± 2.0%) on Gadophrin‐enhanced MRI and at postmortem, respectively. Similarly, greater impairment in ejection fraction was observed in hypertrophied hearts with MRI (39 ± 4% vs. 49 ± 2%; P = 0.02). Gadophrin‐3 provides accurate estimation of infarct size in hypertrophied hearts. Hypertrophied hearts are more sensitive to ischemia than nonhypertrophied hearts. The complementary assessment of Gadophrin‐enhancement and LV function with MRI provides unique information about myocardium sensitivity to ischemia. Magn Reson Med 51:552–558, 2004. © 2004 Wiley‐Liss, Inc.
Chemical shift and magnetic susceptibility contributions to the separation of intracellular and supernatant resonances in variable angle spinning NMR spectra of erythrocyte suspensions
Authors: Philp David J. , Bubb William A. , Kuchel Philip W.
Published: February 2004

Factors contributing to the observation of two separate water resonance arising from erythrocyte suspensions under magic‐ and variable‐angle spinning conditions were examined. By observing the 1H NMR spectra of different chemical species in erythrocytes at different spinning angles, two major effects of comparable magnitude were shown to contribute to the separation: 1) an isotropic chemical shift difference, and 2) a susceptibility difference between the intracellular and supernatant compartments. When the sample was spun at the magic angle, the susceptibility difference did not contribute to the separation. Use of different angles between the spinning axis and the main magnetic field provided a method for quantifiying the isotropic chemical shift and susceptibility differences between the compartments. Magn Reson Med 51:441–444, 2004. © 2004 Wiley‐Liss, Inc.
Accelerated masonry construction review and future prospects
Authors: Ramamurthy K , Kunhanandan Nambiar E K
Published: February 2004

The limitations of conventional masonry cited quite often with respect to constructional, structural and functional performances are summarized, along with attempts to overcome these limitations through different methods of accelerating masonry construction (increasing size of masonry units, elimination of bedding mortar through adoption of: (i) conventional blocks using surface bonding or partial grouting; and (ii) interlocking blocks using dry‐stacking, or surface bonding) developed and proof‐tested or adopted in practice. The accelerated mortarless masonry constructions developed or being used in different countries and by various researchers vary in material, geometry and interlocking mechanism. A classification of interlocking block masonry systems is made, along with a review on the behaviour of some of these systems. The issues to be addressed by researchers in order to achieve a ‘High‐performance masonry’ are highlighted.
Vibration characteristics of steel–concrete composite floor systems
Authors: Hicks Stephen
Published: February 2004

Trends towards long‐span, lightweight floors in steel–concrete composite construction are resulting in structures possessing low natural frequencies, and potentially susceptible to vibration problems. The most common source of vibrations is caused by human activities on the floor, however, in some instances, mechanically induced vibrations from air conditioning plant, etc. may also be problematic. In this paper the serviceability assessment of floor vibration occasioned by walking activities is considered.

Over 30 years ago concerns were raised regarding vibrations induced by walking on steel–concrete composite floors that satisfied traditional deflection criteria. In response to these concerns, design criteria based on a simple impulsive loading function from a person rising onto the balls of the feet, and suddenly dropping onto the heels has been used as a measure of floor acceptability. More recently, design procedures have been developed that more realistically consider the excitation of the floor from walking activities.

In the first part of this paper a historical review of acceptability criteria for floor vibrations will be made. Following this, the current design methodologies for steel–concrete composite floors will be reviewed prior to the presentation of results from a series of in situ vibration tests on a wide variety of floor types. After comparing the test results with current guidance, design recommendations and suggestions for future research will be given.
US–Japan cooperative earthquake research program on CFT structures: achievements on the Japanese side
Authors: Nishiyama Isao , Morino Shosuke
Published: February 2004

The US–Japan Cooperative Earthquake Research Program began in 1979, following the recommendations as outlined in the final report of the US–Japan Planning Group for the Program. The first four phases of the Program have been implemented on: (1) reinforced concrete; (2) structural steel; (3) masonry, and (4) precast/prestressed concrete. Phase 5, on composite and hybrid structures, was carried out from the fiscal year 1993 over 5‐years. In this phase, the following four research topics were executed: (1) new materials, elements and systems; (2) concrete‐filled structural steel tube column systems; (3) reinforced concrete column and structural steel beam systems; and (4) reinforced concrete and steel‐reinforced concrete wall systems.

In this paper, the technical research conducted on the Japanese side related to the research topic of the concrete‐filled structural steel tube column system is overviewed and summarized. It includes experimental results (columns, beam–columns and beam–and‐column subassemblages), proposed design recommendations and a design implication study.
Structural damage in steel construction: regulatory aspects
Authors: Mirambell Enrique
Published: February 2004

This article reviews the damage found more or less systematically in the construction of carbon steel structures. The types of damage that occur and their causes are reviewed from a general standpoint, taking into account steel construction in buildings and public works. Classification of this damage and its analysis are made on the basis of the construction process, with particular emphasis on aspects linked to the design stage. We also look at certain regulatory considerations.
Function and technology of historic cross vaults
Authors: Theodossopoulos D , Sinha B P
Published: February 2004

This paper presents an outline of the technology of historic masonry cross vaults. The development of construction techniques for this roofing system has been highly dependent upon understanding the crucial role played by ribs in Gothic architecture in which a wide variety of forms was produced during the evolution of the structural scheme of buildings. Many of these technical issues were examined during the construction of a 1/4‐scale model cross vault, as part of an experimental project to assess the degree of safety of these structures. The model represents the remaining aisle vaults of the partially collapsed Holyrood Abbey church in Edinburgh, and was tested to failure by movement of abutments. Cross vaults are an integral part of the structure of many historic buildings, and knowledge of their technology and safety can significantly enhance the effectiveness of a conservation project.
Why educate “little scientists?” Examining the potential of practice‐based scientific literacy
Authors: Kevin O'Neill D. , Polman Joseph L.
Published: February 2004

In recent years, a number of curriculum reform projects have championed the notion of having students do science in ways that move beyond hands‐on work with authentic materials and methods, or developing a conceptual grasp of current theories. These reformers have argued that students should come to an understanding of science through doing the discipline and taking a high degree of agency over investigations from start to finish. This stance has occasionally been mocked by its critics as an attempt to create “little scientists”—a mission, it is implied, that is either romantic or without purpose. Here, we make the strong case for a practice‐based scientific literacy, arguing through three related empirical studies that taking the notion of “little scientists” seriously might be more productive in achieving current standards for scientific literacy than continuing to refine ideas and techniques based on the coverage of conceptual content. Study 1 is a classroom case study that illustrates how project‐based instruction can be carried out when teachers develop guidance and support strategies to bootstrap students' participation in forms of inquiry they are still in the process of mastering. Study 2 shows how sustained on‐line work with volunteer scientists appears to influence students' success in formulating credible scientific arguments in written project reports following an authentic genre. Study 3, using data from three suburban high school classes, suggests that involving students in the formulation of research questions and data analysis strategies results in better spontaneous use of empirical data collection and analysis strategies on a transfer task. The study also suggests that failing to involve students in the formulation of research can result in a loss of agency. The implications of these findings for future research and practice are discussed. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 234–266, 2004
Implementation variation and fidelity in an inquiry science program: Analysis of GLOBE data reporting patterns
Authors: Penuel William R. , Means Barbara
Published: February 2004

This article examines variations in patterns in the enactment of a large‐scale kindergarten through Grade 12 science inquiry program. Student data reports in the GLOBE program provide a useful measure of implementation because key design elements in the program are student collection and reporting of local environmental data. We examined associations among teachers' responses to survey items to patterns in GLOBE data reporting to develop hypotheses about important contextual factors related to program implementation. Implications for the study of science inquiry programs are discussed. © 2004 Wiley Periodicals, Inc. J Res Sci Teach 41: 294–315, 2004
An overview of the KIN1/PAR‐1/MARK kinase family
Authors: Tassan Jean‐Pierre , Le Goff Xavier
Published: February 2004

Summry— Members of the KIN1/PAR‐1/MARK kinase family are conserved from yeast to humans and share a similar primary structural organization. Several kinases of this family appear to be at the crossroads of various biological functions including cell polarity, cell cycle control, intracellular signalisation, microtubules stability and protein stability. Here we present an overview of known roles of KIN1/PAR‐1/MARK kinases including pEg3 a newly identified member which is regulated during the cell cycle and is a potential regulator of the cell cycle progression. Some common modes of action can be deciphered for this protein kinase family.
The mitotic spindle and actin tails
Authors: Karsenti Eric , Nédélec François
Published: February 2004

Summry— To segregate their chromosomes, eukaryotic cells rely on a dynamic structure made of microtubules: the mitotic spindle. This structure can form in cells lacking centrosomes, because their chromosomes also nucleate microtubules. This second assembly pathway is observed even in some cells that naturally have centrosomes, for example when the centrosomes are ablated by laser surgery. Recent results have started to address the complementary question of whether centrosome‐nucleated microtubules alone could sustain the formation of a functional mitotic spindle. We wonder in this respect whether lower eukaryotes such as yeasts are different from higher eukaryotes such as vertebrates.
Effects of the combined continuous administration of morphine and the high‐efficacy 5‐HT1A agonist, F 13640 in a rat model of trigeminal neuropathic pain
Authors: Deseure Kristof R. , Adriaensen Hugo F. , Colpaert Francis C.
Published: February 2004

F 13640 is a recently discovered high‐efficacy 5‐HT1A receptor agonist that has demonstrated robust anti‐allodynic efficacy in a rat model of trigeminal neuropathic pain upon acute and continuous administration. In this model, continuous morphine infusion (5 mg/day) was shown to be effective during the first week of its administration but became almost completely ineffective by the end of the second week; F 13640's effectiveness (0.63 mg/day) remained unchanged during two weeks. Here, we examined the effects of combining F 13640 infusion with that of morphine. During the first week, the combination of the two agents produced a magnitude of effect that was similar to that of morphine when given alone and larger than that of F 13640 alone. During the second week, the combination produced an effect that was similar to that of F 13640 alone, and more effective than that of morphine alone. The latter data suggest that the 5‐HT1A agonist, F 13640, inhibits the development of tolerance to morphine in this model. However, it is also possible that little, if any, interaction occurred between the different mechanisms initiated by opioid and 5‐HT1A receptor activation, and that the anti‐allodynic effect that remained by the end of the two‐week treatment period is due solely to 5‐HT1A receptor activation. The stable effects of F 13640 during the second week of treatment surpassed those of morphine and were not improved by the addition of morphine to F 13640.
Modification of attentional biases in chronic pain patients: a preliminary study
Authors: Dehghani M. , Sharpe L. , Nicholas M.K.
Published: February 2004

Research suggests that chronic pain patients demonstrate cognitive biases towards pain‐related information and that such biases predict patient functioning. This study examined the degree to which a successful cognitive‐behavioural program was able to reduce the observed attentional bias towards sensory pain words. Forty‐two patients with chronic pain conditions for more than three months were recruited prior to commencing a cognitive‐behavioural pain management program. Participants were assessed before the program, after the program and at one‐month follow‐up. Results confirmed that chronic pain patients exhibited biased attention towards sensory pain‐related words at pre‐treatment. These biases were still evident at post‐treatment, but were no longer statistically significant at follow‐up. Multiple regression analyses indicated that the changes in attentional bias towards sensory words between post‐treatment and follow‐up were predicted by pre‐ to post‐treatment changes in fear of movement (Tampa Scale for Kinesiophobia) but not other relevant variables, such fear of pain or anxiety sensitivity. These results demonstrate that successful cognitive‐behavioural treatments can reduce selective attention, thought to be indicative of hypervigilance towards pain. Moreover, these biases appear to be changed by reducing the fear associated with movement. Theoretically, these results provide support for the fear of (re)injury model of pain. Clinically, this study supports the contention that fear of (re)injury and movement is an appropriate target of pain management and that reducing these fears causes patients to attend less to pain‐related stimuli.
Clinical predictors of admission status in first episode schizophrenia
Authors: Kelly B.D. , Clarke M. , Browne S. , McTigue O. , Kamali M. , Gervin M. , Kinsella A. , Lane A. , Larkin C. , O’Callaghan E.
Published: February 2004

Having a diagnosis of schizophrenia is a risk factor for involuntary admission to psychiatric inpatient care, but we have a limited understanding of why some patients and not others require involuntary admission. We aimed to identify the predictors of involuntary admission in first episode schizophrenia. We used validated instruments to assess clinical and socio-demographic variables in all patients (n = 78) with first episode schizophrenia from a defined geographical area admitted to a Dublin psychiatric hospital over a 4-year period. Involuntary patients (n = 17) could not be distinguished from voluntary patients (n = 61) on the basis of age, gender, living status, marital status, drug abuse or duration of untreated psychosis. Neither positive nor negative symptoms were useful predictors of admission status. Lack of insight was a strong predictor of involuntary status.
Transforming growth factor‐β1 induced alteration of skeletal morphogenesis in vivo
Authors: Ferguson Cristin M. , Schwarz Edward M. , Puzas J. Edward , Zuscik Michael J. , Drissi Hicham , O'Keefe Regis J.
Published: February 2004

Transforming growth factor beta (TGF‐β) is expressed in the growth plate and is an important regulator of chondrocyte maturation. Loss of function results in premature chondrocyte maturation both in vitro and in vivo. While TGF‐β inhibits chondrocyte maturation in cell cultures, the effect of increased TGF‐β has not been well characterized in an in vivo development model. Addition of Affi‐gel agarose beads loaded with TGF‐β1 (10 ng/μl) to developing stage 24–25 chick limb buds resulted in limb shortening and altered morphology. In situ hybridization studies showed down regulation of Indian hedgehog (ihh), bone morphogenetic protein 6 (bmp6), and collagen type X (colX) expression, markers of chondrocyte maturation, in TGF‐β1 treated limbs. TGF‐β1 also decreased chondrocyte proliferation in the developing anlage. The findings confirm a critical role for TGF‐β during skeletal development. A more complete understanding of the role of TGF‐β and its down‐stream signals will lead to improved understanding and treatment of cartilage diseases. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
On the estimation of stock‐market reaction to corporate layoff announcements
Authors: Hahn TeWhan , Reyes Mario G.
Published: February 2004

This study investigates the stock‐market reaction to layoff announcements where more than 1000 workers are affected. We employ a dummy variable regression (DVR) version of the market model and compare the results obtained using ordinary least squares (OLS) versus exponential GARCH (EGARCH), and value‐weighted (VW) versus equally weighted (EW) market index. We find that the stock market responds negatively to layoffs attributed to low demand. We also find that contrary to prior research, the market reacts positively to restructuring‐related layoffs on the announcement date. This pattern of market reaction is observed regardless of the market index used or the parameter estimation methods employed, although the empirical results indicate that using EGARCH/VW market index tends to generate fewer statistically significant test results and smaller (in the absolute size of the cumulative) abnormal returns (ARs). Taken together, our study provides additional support for the claim that studies of stock‐market reaction to corporate events must account for the time variation in return volatility. Ignoring these could result in erroneous inferences.
Specific isomyosin proportions in hyperexcitable and physiologically denervated mouse muscle
Authors: Agbulut Onnik , Noirez Philippe , Butler-Browne Gillian , Jockusch Harald
Published: February 2004

We show here, by high resolution sodium dodecyl sulfate gel electrophoresis, that the proportions of myosin heavy chain (MyHC) isoforms of mouse muscles are specifically shifted by hereditary neuromuscular diseases. In wild‐type and dystrophic MDX anterior tibial muscle (TA) about 60% of the MyHC is IIB, 30% IIX, at most 10% IIA and <2% type I (slow). In myotonic fast muscles, hyperexcitability leads to a drastic reduction of MyHC IIB which is compensated by IIA. Slow muscles, like soleus and diaphragm, were only marginally changed by myotonia. The MyHC pattern of TA of spinal muscular atrophy (SMA) ‘wobbler’ mice is shifted to a faster phenotype, with nearly 90% IIB. In the SMA mutant ‘muscle deficient’, all four adult isomyosins are expressed in the TA. These findings may be relevant for the future diagnosis of neurological disorders both in mouse disease models and in human patients.
Probing the depths
Authors: CLARKE ANDREW
Published: February 2004

When scientists from HMS Challenger dredged animals from over 5km depth, they finally laid to

rest the azoic hypothesis of Edward Forbes, that life could not exist in cold dark depths of the
ocean, and thereby opened the doors to true deep-sea biology. The past decade has witnessed a further
sea change in our view of marine diversity, if I may be permitted the pun, a change driven to a large
extent by improved knowledge from Antarctica. For many years we viewed the tropics as the engines
of diversity; species arose in warm clear seas, especially those associated with coral reefs, and spread
slowly to populate the harsher high latitudes. Early studies of the isopod fauna had also suggested that
at least some organisms living on the continental shelf of Antarctica may have originated in the deep
sea. After a period of intense work, much of it under the auspices of the SCAR EASIZ (Ecology of the
Antarctic Sea Ice Zone) and more recently the EVOLANTA(Evolution in Antarctica) programmes, we
can now modify both hypotheses, with powerful implications for our understanding of global marine
diversity. The marine invertebrate fauna of the Antarctic continental shelf is now better described than
might be thought, and the total fauna may well exceed 17000 taxa. Interestingly, there are very few
places in the world with comparable data, but we can say that the fauna has had a long history of
evolution in situ and is not simply a last refuge for taxa that originated elsewhere.
How many macrozoobenthic species might inhabit the Antarctic shelf?
Authors: GUTT JULIAN , SIRENKO BORIS I. , SMIRNOV IGOR S. , ARNTZ WOLF E.
Published: February 2004

Based on data from the Weddell Sea in the Atlantic sector of the Southern Ocean, the total number of macrozoobenthic species was estimated for the entire Antarctic shelf using species-accumulation methods, jack-knife estimators, and Incidence-based Coverage Estimators of species richness. Ranging between 11 000 and 17 000 expected species, Antarctica seems to have an intermediate species richness when compared to other selected tropical, temperate or Arctic habitats.