bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo 13C saturation transfer effect of the lactate dehydrogenase reaction
Authors: Xu Su , Yang Jehoon , Shen Jun 
Published: January 2007

AbstractLactate dehydrogenase (LDH, EC 1.1.1.27) catalyzes an exchange reaction between pyruvate and lactate. It is demonstrated here that this reaction is sufficiently fast to cause a significant magnetization (saturation) transfer effect when the 13C resonance of pyruvate is saturated by a continuous‐wave (CW) RF pulse. Infusion of [2‐13C]glucose was used to allow labeling of pyruvate C2 at 207.9 ppm to determine the pseudo first‐order rate constant of the unidirectional lactate → pyruvate flux in vivo. During systemic administration of GABAA receptor antagonist bicuculline, this pseudo first‐order rate constant was determined to be 0.08 ± 0.01 s−1 (mean ± SD, N = 4) in halothane‐anesthetized adult rat brains. In 9L and C6 rat glioma models, the 13C saturation transfer effect of the LDH reaction was also detected in vivo. Our results demonstrate that the 13C magnetization transfer effect of the LDH reaction may be useful as a novel marker for utilizing noninvasive in vivo MRS to study many physiological and pathological conditions, such as cancer. Magn Reson Med 57:258–264, 2007. © 2007 Wiley‐Liss, Inc.
Frequency stabilization using infinite impulse response filtering for SSFP fMRI at 3T
Authors: Wu Ming‐Long , Wu Pei‐Hsin , Huang Teng‐Yi , Shih Yi‐Yu , Chou Ming‐Chung , Liu Hua‐Shan , Chung Hsiao‐Wen , Chen Cheng‐Yu 
Published: January 2007

AbstractThe steady‐state free precession (SSFP) method has been shown to exhibit strong potential for distortion‐free functional magnetic resonance imaging (fMRI). One major challenge of SSFP fMRI is that the frequency band corresponding to the highest functional sensitivity is extremely narrow, leading to substantial loss of functional contrast in the presence of magnetic field drifts. In this study we propose a frequency stabilization scheme whereby an RF pulse with small flip angle is applied before each image scan, and the initial phase of the free induction decay (FID) signals is extracted to reflect temporal field drifts. A simple infinite impulse response (IIR) filter is further employed to obtain a low‐pass‐filtered estimate of the central reference frequency for the upcoming scan. Experimental results suggest that the proposed scheme can stabilize the frequency settings in accordance with field drifts, with oscillation amplitudes of <0.5 Hz. Phantom studies showed that both slow drifts and fast fluctuations were prominently reduced, resulting in less than 5% signal variations. Visual fMRI at submillimeter in‐plane resolution further demonstrated 15% activation signals that were nicely registered in the microvessels within the sulci. It is concluded that the IIR‐filtered frequency stabilization is an effective technique for achieving reliable SSFP fMR images at high field strengths. Magn Reson Med 57:369–379, 2007. © 2007 Wiley‐Liss, Inc.
Optimizing the precision‐per‐unit‐time of quantitative MR metrics: Examples forT1,T2, and DTI
Authors: Fleysher Lazar , Fleysher Roman , Liu Songtao , Zaaraoui Wafaa , Gonen Oded 
Published: January 2007

AbstractQuantitative MR metrics (e.g.,T1,T2, diffusion coefficients, and magnetization transfer ratios (MTRs etc)) are often derived from two images collected with one acquisition parameter changed between them (the “two‐point” method). Since a low signal‐to‐noise‐ratio (SNR) adversely affects the precision of these metrics, averaging is frequently used, although improvement accrues slowly—in proportion to the square root of imaging time. Fortunately, the relationship between the images' SNRs and the metric's precision can be exploited to our advantage. Using error propagation rules, we show that for a given sequence, specifying the total imaging time uniquely determines the optimal acquisition protocol. Specifically, instead of changing only one acquisition parameter and repeating the imaging pair until all available time is spent, we propose to adjustallof the parameters and the number of averages at each point according to their contribution to the sought metric's precision. The tactic is shown to increase the precision of the well‐known two‐pointT1,T2, and diffusion coefficients estimation by 13–90% for the same sample, sequence, hardware, and duration. It is also shown that under this general framework, precision accrues faster than the square root of time. Tables of optimal parameters are provided for various experimental scenarios. Magn Reson Med 57:380–387, 2007. © 2007 Wiley‐Liss, Inc.
Theoretical MRI contrast model for exogenous T2 agents
Authors: Mills Parker H. , Ahrens Eric T. 
Published: January 2007

AbstractThe rational development of new generations of MRI contrast agents (CAs) requires a scheme for predicting contrast enhancement. Previous contrast predictions have been based largely on empirical results in specific systems. Here we present a general theoretical model for evaluating the minimum concentration of T2 CA required for satisfactory image contrast. This analytic contrast model is applicable to a wide range of T2‐type agents and delivery scenarios, and requires only a few readily evaluated parameters. We demonstrated the model by predicting contrast produced by superparamagnetic ferumoxide and the iron storage protein, ferritin. We then experimentally verified the predictions using suspensions of Feridex® and ferritin in phantoms. The model was also used to compare the contrast efficacy of the metal ions in two clinically approved T1‐ and T2‐type CAs. In the Appendix we present a numerical formalism that is useful for relating image contrast and agent concentration when gradient‐echo (GRE) T‐weighted (TW) pulse sequences are used. Magn Reson Med 57:442–447, 2007. © 2007 Wiley‐Liss, Inc.
Fractional encoding of harmonic motions in MR elastography
Authors: Rump Jens , Klatt Dieter , Braun Jürgen , Warmuth Carsten , Sack Ingolf 
Published: January 2007

AbstractIn MR elastography (MRE) shear waves are magnetically encoded by bipolar gradients that usually oscillate with the same frequency fv as the mechanical vibration. As a result, both the repetition time (TR) and echo time (TE) of such an MRE sequence are greater than the vibration period 1/fv. This causes long acquisition times and considerable signal dephasing in tissue with short transverse relaxation times. Here we propose a reverse concept with TR ≤ 1/fv which we call “fractional” MRE, i.e., only a fraction of one vibration cycle per TR, can be used for motion sensitization. The benefit of fractional MRE is twofold: 1) acquisition times in seconds can be achieved for a single‐phase difference wave image, and 2) materials that combine low elasticity, high viscosity, and short T relaxation times show an increased phase‐to‐noise ratio (PNR). A twofold increase of the phase signal is predicted for liver‐like materials. Volunteer studies performed in liver and biceps show the benefit of fractional MRE. Furthermore, we demonstrate the feasibility of the technique for in vivo myocardial MRE by visualizing transverse wave propagation in the interventricular septum (IVS). Magn Reson Med 57:388–395, 2007. © 2007 Wiley‐Liss, Inc.
Short‐term efficacy of group pelvic floor training under intensive supervision versus unsupervised home training for female stress urinary incontinence: A randomized pilot study
Authors: Konstantinidou Eleni , Apostolidis Apostolos , Kondelidis Nikolaos , Tsimtsiou Zoi , Hatzichristou Dimitrios , Ioannides Evangelos 
Published: January 2007

AbstractAimsCurrent management guidelines propose pelvic floor muscle training (PFMT) as first line treatment for female stress urinary incontinence (SUI). The aim of this study is to compare the efficacy of group PFMT under intensive supervision to that of individual home therapy in women with SUI.Material and MethodsThirty women with clinical and urodynamic diagnosis of SUI were randomized in two equal‐number groups. Following a common demonstration course, Group A women received a detailed schedule for home training, while Group B in addition attended a weekly hospital group visit. At 12 weeks both groups were assessed for changes in subjective and objective outcomes.ResultsTwenty‐two women, (10 Group A, 12 Group B) with a mean age of 47.3 years completed the study. Although significant (P < 0.05) improvements were noted in both groups in quality of life scores, number of incontinence episodes/week, 24‐hr frequency, and endurance, repetitions and fast contractions upon vaginal assessment of the PFMs, comparative analysis at the end of the study demonstrated significantly better results for women in Group B, who also improved in daily pad usage, underwear wetting, modified Oxford grading of the PFMs and hold with cough. Consequently, significantly more women in Group B reported improvement in their continence (100% vs. 20% in Group A).ConclusionsGroup PFMT under intensive supervision produced significantly better improvements in primary and secondary outcomes in the short‐term compared to individual, unsupervised home application of PFMT. Neurourol. Urodynam. 26:486–491, 2007. © 2007 Wiley‐Liss, Inc.
Just keep it simple: a field experiment on fundraising letters
Authors: Bekkers René , Crutzen Olaf 
Published: January 2007

Abstract

This paper studies how the use of a colour picture in fundraising letters affect response rates and the amount donated in a fundraising campaign. Envelopes, with a full colour picture were tested against envelopes, without a picture in a controlled field experiment at a national religious charity in the Netherlands. Letters (89 937) were sent out to planned as well as incidental donors in four experimental groups. Results show that packages with more graphics yield lower donations, because both response rates are lower and the amount donated per letter is lower. We interpret this finding from donor aversion against high fundraising costs.
Copyright © 2007 John Wiley & Sons, Ltd.
Influence of hyperbranched against linear architecture on crystallization behavior of poly(ε‐caprolactone)s in binary blends with poly(vinyl chloride)
Authors: Choi Jeongsoo , Chun Sang‐Wook , Kwak Seung‐Yeop 
Published: January 2007

AbstractNonisothermal and isothermal crystallization behaviors of the hyperbranched poly(ε‐caprolactone) (HPCL)/poly(vinyl chloride) (PVC) and linear poly(ε‐caprolactone) (LPCL)/(PVC) blends were characterized with various blend composition such as 100/0, 95/5, 90/10, and 80/20, respectively. HPCL was synthesized through polycondensation of AB2 macromonomer while LPCL and PVC were commercially purchased. The architectural characterization performed on 1H NMR spectra revealed that HPCL consisted of about 3 AB2 units and the linear segments consisted of 25 ε‐CL units. Through the nonisothermal crystallization analyses by modified Avrami approach with DSC crystallization exotherms, it was found that the crystallization rate was retarded by the increase in the noncrystallizable component (PVC) in the blends. This is in good agreement with the results of the isothermal crystallization analyses where time resolved small angle light scattering (SALS) and polarized optical microscopy (POM) were used. The effect of molecular architectural difference between HPCL and LPCL on the crystallization of their binary blends with PVC was elucidated by comparing the crystallization kinetic parameters. Both the nonisothermal and isothermal crystallization analyses showed that the crystallization rates of HPCL/PVC blends was faster than LPCL/PVC blends at given blend compositions. The faster crystallization of the HPCL/PVC blends is ascribed to the two specific architectural characteristics of HPCL; the branched structure and the incorporated long linear segments. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 577–589, 2007
Tests of walking ability at different speeds in patients with knee osteoarthritis
Authors: Börjesson Margareta , Weidenhielm Lars , Elfving Britt , Olsson Elisabeth 
Published: January 2007

AbstractBackground and Purpose. Measurements of walking speeds are commonly used as an objective measure of functional performance in patients with knee osteoarthritis (OA) and are easily performed in a clinical setting. However, the choice in which the walking speed evaluation should be performed is controversial. The aim of this study was to identify the most discriminating walking speed after surgical interventions in patients with knee osteoarthritis, and to compare the responsiveness of the different gait speeds. Method. A prospective clinical one‐year follow‐up study involving 54 patients with knee osteoarthritis (63 (±5) years of age) who were operated with either a unicompartmental knee arthroplasty or a high tibial osteotomy was undertaken. Thirty‐nine patients had unilateral knee OA and 15 patients had bilateral knee OA or other symptoms from the lower extremities that could influence walking. The patients were examined at a gait laboratory before surgery, and one year after surgery. The patients were instructed to walk at slow, normal and fast walking speed. Results. All patients (n =54) walked faster one year after the surgical intervention compared to before surgery (p =0.001) at slow (+15%), normal (+8%) and fast (+7%) walking speed. This increase was similar for the three walking speeds (p =0.171). Patients with unilateral knee OA (n =39) reached an average change of+0.12 m/s, which was considered clinically important, while patients with bilateral knee OA (n =15) did not increase their walking speed>0.12 m/s. Effect size was moderate for slow walking speed and small for normal and fast walking speeds, respectively. Conclusions. The different walking speeds were equally good in detecting changes one year after surgical interventions. In this study, responsiveness favoured slow walking speed, however, the advantages of normal walking speed are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
Interaction of spatially separated oxygen–vacancy centers in CaF2 crystals due to an excitation‐induced short‐time molecular bond
Authors: Pologrudov V. V. , Penzina E. E. , Kheder K. K. 
Published: January 2007

AbstractElectro‐physical and optical methods have been used to investigate oxygen–vacancy centers in CaF2:O2– crystals. The study revealed a new luminescence excitation band peaking at 4.27 eV. The excitation with the light from the region of this band is accompanied by electron transfer. It is found that the decay of luminescence is not exponential and is described by Becquerel's empirical law. New evidence has been obtained for thermostimulated depolarization associated with both ionic and electronic phenomena within the crystal. Activation energies for thermostimulated processes have been estimated. The results can be interpreted as providing evidence for the excitation‐induced short‐time molecular bond between spatially separated oxygen–vacancy defects. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Impedance characteristics of Pb(Fe2/3W1/3)O3–BiFeO3 composites
Authors: Choudhary R. N. P. , Pradhan Dillip K. , Tirado C. M. , Bonilla G. E. , Katiyar R. S. 
Published: January 2007

AbstractA single phase formation of PFW (Pb(Fe2/3W1/3)O3)–BFO (BiFeO3) composites prepared by mechanical activation, followed by mixed oxide method was checked by an X‐ray diffraction technique. Detailed studies of the impedance parameters suggest that addition of small amount of multiferroic BFO (10%) in PFW matrix produces a low frequency dielectric dispersion (i.e., relaxor characteristics) in the composite phase. Non‐Debye type of relaxation phenomena has been observed in the PFW‐BFO composites. The higher value of ε ′ at the lower frequency is explained on the basis of the Maxwell–Wagner (MW) polarization model. Complex impedance analysis enable us to separate grain and grain boundary contributions of materials, and it is found that grain boundary resistance is greater than grain resistance irrespective of composition at higher temperatures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Establishing experiences to develop a wisdom of professional practice
Authors: Walker Joan M. T. , Brophy Sean P. , Hodge Lynn Liao , Bransford John D. 
Published: January 2007

AbstractThis study evaluated students' perceptions of two types of instructional materials focused on engineering professionalism: a passage of advice about professionalism and the same passage with a video enacting the advice. The role of experience in learning about professionalism is discussed, with particular emphasis on how educational materials might be tailored to meet the needs of first‐year and advanced undergraduates.
Learning content using complex data in project‐based science: An example from high school biology in urban classrooms
Authors: Kanter David E. , Schreck Melissa 
Published: January 2007

AbstractThis chapter explores the extent to which project‐based science (PBS) curricula designed with supports for students' inquiry into complex scientific data can help urban students make sense of such data and promote their deep understanding of standards‐based content. We review qualitative and quantitative data from classroom enactments of a PBS high school biology curriculum called Disease Detectives.
Transient bilateral ovarian enlargement associated with large retroperitoneal lymphoma
Authors: Dalloul M. , Sherer D. M. , Gorelick C. , Serur E. , Zinn H. , Sanmugarajah J. , Zigalo A. , Abulafia O. 
Published: January 2007

AbstractBilateral ovarian enlargement may reflect benign or malignant processes of the ovary. Benign causes of ovarian enlargement include luteomas, tumors such as mature cystic teratomas, fibrothecomas, cystadenomas and rare conditions including capillary hemangioma and massive edema of the ovaries. Ovarian malignancies include epithelial, stromal and germ‐cell tumors. Primary malignancies that may exhibit metastases to the ovaries include gastrointestinal, breast and soft tissue tumors such as lymphoma. We present an unusual case in which a patient presenting with weakness and mild lower abdominal and pelvic pain was noted at sonography to have bilaterally enlarged ovaries with features similar to those of massive ovarian edema as described previously, which has been associated with venous and lymphatic obstruction. Subsequent computerized tomography (CT) imaging depicted a large retroperitoneal tumor, CT‐guided biopsy of which revealed diffuse large B cell lymphoma. The patient responded well to chemotherapy with significant shrinkage of the tumor, and reappearance of normal findings on ovarian sonography. This case demonstrates that bilaterally enlarged ovaries may be the first clinical evidence of a large retroperitoneal tumor and that in such cases CT imaging may be warranted. Copyright © 2007 ISUOG. Published by John Wiley & Sons, Ltd.
Beyond access and supply: Youth‐led strategies to captivate young people's interest in and demand for youth programs and opportunities
Authors: Saito Rebecca N. 
Published: January 2007

AbstractWorking on supply and access are necessary but not sufficient for the task of increasing young people's engagement in positive youth programs, activities, and informal opportunities. Youth become the marketing experts in this endeavor to increase participation in youth programs, particularly by those who typically do not participate.
Reaction of γ‐Tocopherol with Hypochlorous Acid
Authors: Nguyen Quyen , Southwell‐Keely Peter T. 
Published: January 2007

AbstractIn addition to being a very good antioxidant, γ‐tocopherol is also an excellent electrophile trap. This is a study of the reactivity of γ‐tocopherol with hypochlorous acid/hypochlorite, a potential biological foe that is both an oxidant and an electrophile. Aqueous sodium hypochlorite (1.72 mmol; pH 7.4) was stirred with γ‐tocopherol (0.12 mmol) in hexane for 2 min at room temperature. The following products were isolated: γ‐tocopheryl quinone (0.6%), tocored (10%), 3‐chloro‐γ‐tocopheryl quinone (14%), an ether dimer of 3‐chloro‐γ‐tocopheryl quinone (0.4%), two isomers of 5‐(5‐γ‐tocopheryl)‐γ‐tocopherol (3 and 2% respectively), 5‐chloro‐γ‐tocopherol (14%) and two chlorinated dimers (14 and 24% respectively) which were identified as diastereomers of (3R,10R)‐11a‐chloro‐2,3,9,10‐tetrahydro‐3,5,6,10,12,13‐hexamethyl‐3,10‐bis[(4R,8R)‐4,8,12‐trimethyltridecyl]‐1H‐pyrano(3,2a)‐8H‐pyrano(3,2g)‐dibenzofuran‐14(7aH)(14aH)‐one. The chlorinated dimers, 5‐chloro‐γ‐tocopherol, 3‐chloro‐γ‐tocopheryl quinone and its ether dimer are new compounds.
Butters Varying in trans 18:1 and cis‐9,trans‐11 Conjugated Linoleic Acid Modify Plasma Lipoproteins in the Hypercholesterolemic Rabbit
Authors: Bauchart Dominique , Roy Alexandre , Lorenz Stephanie , Chardigny Jean‐Michel , Ferlay Anne , Gruffat Dominique , Sébédio Jean‐Louis , Chilliard Yves , Durand Denys 
Published: January 2007

AbstractThe experiment was designed to study the effects of butters differing in conjugated linoleic acid (CLA) and trans 18:1 contents on lipoproteins associated with the risk of atherogenesis. New Zealand White male rabbits (9.6 weeks; 2.1 kg) were assigned for 6 or 12 weeks to three diets (n = 6 per diet) made of conventional pellets with 0.2% cholesterol and with 12% fat provided from a butter poor in trans‐10 and trans‐11 18:1 and in CLA (standard group), or rich in trans‐10 18:1 (trans‐10 18:1 group) or rich in trans‐11 18:1 and in cis‐9,trans‐11 CLA (trans‐11 18:1/CLA group). Blood samples were collected at the end of dietary treatments. Lipoproteins were separated by gradient‐density ultracentrifugation. Lipid classes were determined enzymatically and apolipoproteins A‐I and B by radial immunodiffusion. Mainly in the 12‐week rabbits, higher plasma triglycerides and apolipoprotein B levels shown in the standard and trans‐10 18:1 groups compared with those in the trans‐11 18:1/CLA group are associated with higher plasma levels of very low density lipoproteins (VLDL) and low density lipoproteins (LDL) also shown in these two groups. In the 12‐week rabbits, a shift towards denser LDL, considered as more atherogenic, was shown only in the trans‐10 18:1 group. In these animals, the VLDL + LDL to HDL ratio was 1.7–2.3 times higher in the trans‐10 18:1 group than in the other groups (P = 0.076). These results suggest a rather neutral effect of trans‐11 18:1/CLA butter towards the risk of atherogenesis, whereas trans‐10 18:1 butter would tend to be detrimental.