bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microfilament and microtubule assembly is required for the propagation of inositol trisphosphate receptor‐induced Ca2+ waves in bovine aortic endothelial cells
Authors: Béliveau Éric , Guillemette Gaétan 
Published: December 2008

AbstractCa2+ is a highly versatile second messenger that plays a key role in the regulation of numerous cell processes. One‐way cells ensure the specificity and reliability of Ca2+ signals is by organizing them spatially in the form of waves that propagate throughout the cell or within a specific subcellular region. In non‐excitable cells, the inositol 1,4,5‐trisphosphate receptor (IP3R) is responsible for the release of Ca2+ from the endoplasmic reticulum. The spatial aspect of the Ca2+ signal depends on the organization of various elements of the Ca2+ signaling toolkit and varies from tissue to tissue. Ca2+ is implicated in many of endothelium functions that thus depend on the versatility of Ca2+ signaling. In the present study, we showed that the disruption of caveolae microdomains in bovine aortic endothelial cells (BAEC) with methyl‐ß‐cyclodextrin was not sufficient to disorganize the propagation of Ca2+ waves when the cells were stimulated with ATP or bradykinin. However, disorganizing microfilaments with latrunculin B and microtubules with colchicine both prevented the formation of Ca2+ waves. These results suggest that the organization of the Ca2+ waves mediated by IP3R channels does not depend on the integrity of caveolae in BAEC, but that microtubule and microfilament cytoskeleton assembly is crucial. J. Cell. Biochem. 106: 344–352, 2009. © 2008 Wiley‐Liss, Inc.
The polyamine analogue N1,N11‐diethylnorspermine can induce chondrocyte apoptosis independently of its ability to alter metabolism and levels of natural polyamines
Authors: Stanic' Ivana , Facchini Annalisa , Borzì Rosa Maria , Stefanelli Claudio , Flamigni Flavio 
Published: December 2008

AbstractWe have been investigating the effects of natural polyamines and polyamine analogues on the survival and apoptosis of chondrocytes, which are cells critical for cartilage integrity. Treatment of human C‐28/I2 chondrocytes with N1,N11‐diethylnorspermine (DENSPM), a polyamine analogue with clinical relevance as an experimental anticancer agent, rapidly induced spermidine/spermine N1‐acetyltransferase (SSAT) and spermine oxidase (SMO), key enzymes of polyamine catabolism and down‐regulated ornithine decarboxylase, the first enzyme of polyamine biosynthesis, thus depleting all main polyamines within 24 h. The treatment with DENSPM did not provoke cell death and caspase activation when given alone for 24 h, but caused a caspase‐3 and ‐9 dependent apoptosis in chondrocytes further exposed to cycloheximide (CHX). In other cellular models, enhanced polyamine catabolism or polyamine depletion has been implicated as mechanisms involved in DENSPM‐related apoptosis. However, the simultaneous addition of DENSPM and CHX rapidly increased caspase activity in C‐28/I2 cells in the absence of SSAT and SMO induction or significant reduction of polyamine levels. Moreover, caspase activation induced by DENSPM plus CHX was not prevented by a N1‐acetylpolyamine oxidase (PAO)/SMO inhibitor, and depletion of all polyamines obtained by specific inhibitors of polyamine biosynthesis did not reproduce DENSPM effects in the presence of CHX. DENSPM/CHX‐induced apoptosis was associated with changes in the amount or activation of signalling kinases, Akt and MAPKs, and increased uptake of DENSPM. In conclusion, the results suggest that DENSPM can favour apoptosis in chondrocytes independently of its effects on polyamine metabolism and levels. J. Cell. Physiol. 219: 109–116, 2009. © 2008 Wiley‐Liss, Inc.
Computational and experimental optimization of a double‐tuned 1H/31P four‐ring birdcage head coil for MRS at 3T
Authors: Duan Yunsuo , Peterson Bradley S. , Liu Feng , Brown Truman R. , Ibrahim Tamer S. , Kangarlu Alayar 
Published: December 2008

AbstractPurposeTo optimize the homogeneity and efficiency of the B1 magnetic field of a four‐ring birdcage head coil that is double‐tuned at the Larmor frequencies of both 31P and 1H and optimized to acquire magnetic resonance spectroscopy (MRS) data at 3T for the study of infants.Materials and MethodsWe developed a finite difference time domain (FDTD) tool in‐house to iteratively compute and seek the range of geometric and electromagnetic parameters of a dual‐tuned, four‐ring birdcage coil that would produce the desired resonance patterns, optimize homogeneity of the B1‐field, and maximize efficiency of the coil. To demonstrate the validity of our computational results, we constructed three RF coils: one dual‐tuned coil that was based on the calculated optimized parameters and two single‐tuned coils that had dimensions similar to those of the dual‐tuned coil, but tuned at the Larmor frequencies of both 31P and 1H, respectively. We then tested and compared the performances of the dual‐tuned coil and single‐tuned coils at both of these frequencies.ResultsWe found that a dual‐tuned, four‐ring birdcage coil with a diameter of 180 mm, an inner birdcage length of 100–300 mm, and an outer birdcage length of 25–100 mm produces the desired resonance patterns. For the use of this coil with human infants, optimization of the homogeneity of the B1 field, combined with improved coil efficiency, yielded a dual‐tuned birdcage coil with diameter of 180mm, an inner birdcage length of 150 mm, an outer birdcage length of 25 mm, and corresponding inner and outer capacitances of 17.2 pF and 7.6 pF, respectively. The experimental results from a constructed coil having the sameparameters with the modeled coil agreed well with the computational results from the modeled coil. This optimized design overcame the deficiencies of existing dual‐tuned, four‐ring birdcage coils.ConclusionThe homogeneity and efficiency of the B1 field for 31P/1H dual‐tuned, four‐ring birdcage coils can be optimized well using our FDTD tool, especially at high static magnetic fields (B0). J. Magn. Reson. Imaging 2009;29:13–22. © 2008 Wiley‐Liss, Inc.
Diffusion measurements and diffusion tensor imaging with noisy magnitude data
Authors: Kristoffersen Anders 
Published: December 2008

AbstractPurposeTo compare an unbiased method for estimation of the diffusion coefficient to the quick, but biased, log‐linear (LL) method in the presence of noisy magnitude data.Materials and MethodsThe magnitude operation changes the signal distribution in magnetic resonance (MR) images from Gaussian to Rician. If not properly taken into account, this will introduce a bias in the estimated diffusion coefficient. We compare two methods by means of Monte Carlo simulations. The first one applies least‐squares fitting of the measured signal to the median (MD) value of the probability density function. The second method is uncorrected LL estimation. We also perform a high‐resolution diffusion tensor experiment.ResultsThe uncorrected LL estimator is heavily biased at low signal‐to‐noise ratios. The bias has a significant effect on image quality. The MD estimator is accurate and produces images with excellent contrast.ConclusionIn the presence of noisy magnitude data, unbiased estimation is essential in diffusion measurements and diffusion tensor imaging. J. Magn. Reson. Imaging 2009;29:237–241. © 2008 Wiley‐Liss, Inc.
New coil positioning method for interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) and its validation in a motor cortex study
Authors: Moisa Marius , Pohmann Rolf , Ewald Lars , Thielscher Axel 
Published: December 2008

AbstractPurposeTo develop and test a novel method for coil placement in interleaved transcranial magnetic stimulation (TMS)/functional MRI (fMRI) studies.Materials and MethodsInitially, a desired TMS coil position at the subject's head is recorded using a neuronavigation system. Subsequently, a custom‐made holding device is used for coil placement inside the MR scanner. The parameters of the device corresponding to the prerecorded position are automatically determined from a fast structural image acquired directly before the experiment. The spatial accuracy of our method was verified on a phantom. Finally, in a study on five subjects, the coil was placed above the cortical representation of a hand muscle in M1 and the blood oxygenation level‐dependent (BOLD) responses to short repetitive TMS (rTMS) trains were assessed using echo‐planar imaging (EPI) recordings.ResultsThe spatial accuracy of our method is in the range of 2.9 ± 1.3 (SD) mm. Motor cortex stimulation resulted in robust BOLD activations in motor‐ and auditoryrelated brain areas, with the activation in M1 being localized in the hand knob.ConclusionWe present a user‐friendly method for TMS coil positioning in the MR scanner that exhibits good spatial accuracy and speeds up the setup of the experiment. The motor‐cortex study proves the viability of the approach and validates our interleaved TMS/fMRI setup. J. Magn. Reson. Imaging 2009;29:189–197. © 2008 Wiley‐Liss, Inc.
Diagnostic utility of diffusion‐weighted MR imaging and apparent diffusion coefficient value for the diagnosis of adrenal tumors
Authors: Tsushima Yoshito , Takahashi‐Taketomi Ayako , Endo Keigo 
Published: December 2008

AbstractPurposeTo determine the utility of diffusion‐weighted MR imaging (DWI) for the diagnosis of adrenal tumors.Materials and MethodsForty‐two patients (24 men and 18 women; age, 61.5 ± 12.7 years old; range, 34–86 years) with 43 adrenal tumors (11 functioning cortical adenomas, 20 nonfunctioning cortical adenomas, 7 metastatic tumors, and 5 pheochromocytomas) were retrospectively investigated. DWIs were obtained by single‐shot spin‐echo type echo‐planar imaging sequence (1.5 Tesla [T]; TR = 8000 ms, TE = 72, b‐factor = 0 and 1000 s/mm2), and apparent diffusion coefficient (ADC) value was calculated. Chemical shift images were obtained by gradient echo sequence (TR = 161, TE = 2.38 [out‐of‐phase, OP] and 4.76 [in‐phase, IP], FA = 60), and the signal intensity index (SII; [IP‐OP]/IP *100%) was calculated.ResultsThere was no difference in ADC values between adenomas (1.09 ± 0.29*10−3 mm2/s; range, 0.52–1.64) and metastatic tumors (0.85 ± 0.26*10−3; 0.51–1.23; p = 0.14). Pheochromocytomas showed the higher mean ADC value (1.59 ± 0.34*10−3; 1.04–1.96) compared with those of adenomas or metastatic tumors (P < 0.05 and P < 0.005, respectively). The mean SII of adenomas (62.1 ± 17.9%; 14.5–88.4) was significantly higher than those of pheochromocytomas (4.0 ± 10.0%; −19.6–3.3; P < 0.005) or metastatic tumors (−1.5 ± 11.7%; −18.3–8.2; P < 0.01). There was no correlation between ADC values and SII.ConclusionAlthough pheochromocytomas showed higher ADC values, we did not find that ADC value had diagnostic utility for differentiating adenomas and metastatic tumors. J. Magn. Reson. Imaging 2009;29:112–117. © 2008 Wiley‐Liss, Inc.
Increased SNR and reduced distortions by averaging multiple gradient echo signals in 3D FLASH imaging of the human brain at 3T
Authors: Helms Gunther , Dechent Peter 
Published: December 2008

AbstractPurposeTo demonstrate how averaging of multiple gradient echoes can improve high‐resolution FLASH (fast low angle shot) magnetic resonance imaging (MRI) of the human brain.Materials and Methods3D‐FLASH with multiple bipolar echoes was studied by simulation and in three experiments on human brain at 3T. First, the repetition time (TR) was increased by the square of the flip angle to maintain contrast as derived by theory. Then the number of echoes was increased at constant TR with bandwidths between 110 and 1370 Hz/pixel. Finally, signals of a 12‐echo acquisition train (echo times 4.9–59 msec) were averaged consecutively to study the increase in SNR.ResultsAt unchanged contrast, the signal increased proportionally with flip angle and sqrt(TR). Increasing the bandwidth improved delineation of the basal cortex and vessels, while most of the loss in the signal‐to‐noise ratio (SNR) was recovered by averaging. Consecutive averaging increased the SNR to reach maximum efficiency at an echo train length corresponding roughly to T.ConclusionSNR is gained efficiently by acquiring additional echoes and increasing TR (and flip angle accordingly to maintain contrast) until the associated T loss in the averaged signal consumes the sqrt(TR) increase in the steady state. A bandwidth of 350 Hz/pixel or higher and echo trains shorter than T are recommended. J. Magn. Reson. Imaging 2009;29:198–204. © 2008 Wiley‐Liss, Inc.
Aflatoxin occurrence in milk and supplied concentrates of goat farms of north‐eastern Italy
Authors: Saccà Elena , Boscolo Daria , Vallati Alberto , Ventura Walter , Bigaran Federico , Piasentier Edi 
Published: December 2008

AbstractBACKGROUND:There is little information about the occurrence of aflatoxin M1in goat milk. A survey involving 17 dairy goat farms of north‐eastern Italy was completed during 2005 and 2006, in order to evaluate the prevalence of milk contamination and its relationship with type and level of concentrate supplied.RESULTS:132 concentrate and 85 milk samples were collected during five farm visits and analysed for aflatoxins. Aflatoxin B1(AFB1) was > 0.1 µg kg−1in two‐thirds of the feeds and > 5 µg kg−1in nine. Contamination was higher in maize than in other pure feeds (median: 0.8versus0.1 µg kg−1); complementary feeds showed intermediate values. Aflatoxin M1(AFM1) was > 3 ng kg−1in one‐third of milks and > 25 ng kg−1in three. All the milk samples were below EU statutory limits. The farm ranks for milk AFM1level and the peak of concentrate AFB1contamination were significantly correlated (0.642).CONCLUSIONS:Risk to human health was generally found to be absent, with only a few cases involving feed contamination to be monitored. The main aflatoxin risk for goat milk could arise from maize and maize‐based concentrates in the more intensive breeding conditions. Copyright © 2008 Society of Chemical Industry
Risk of acute myocardial infarction in patients treated with thiazolidinediones or other antidiabetic medications
Authors: Stockl Karen M. , Le Lisa , Zhang Shaoang , Harada Ann S.M. 
Published: December 2008

AbstractPurposeControversy surrounds the question whether thiazolidinediones (TZDs) increase the risk of acute myocardial infarction (AMI). This study examined risk of AMI in patients with type 2 diabetes mellitus (T2DM) who were taking TZDs or other antidiabetic medications.MethodsUsing a nested case‐control design, a cohort of patients aged 18–84 years with T2DM and use of an oral antidiabetic medication or exenatide between January 2002 and June 2006 was identified. Cases of AMI were matched with up to four controls based on age, gender, health plan, geography, and diabetes therapy regimen. Over the 1‐year pre‐index period, TZD exposure was compared with no TZD exposure, after adjustment for potential confounders.ResultsOverall, 1681 cases were identified and matched with 6653 controls. Compared with no TZD exposure, an increased risk of AMI was not observed among TZD exposed patients (adjusted OR 1.01; 95%CI, 0.85–1.20; adjusted p = 0.98). When exposure proximity to the event was examined, the risk of AMI was significantly increased with recent rosiglitazone exposure between 1 and 60 days prior to the case date (adjusted OR 1.69; 95%CI, 1.18–2.44; adjusted p = 0.045) and was not significantly increased with current or remote rosiglitazone exposure or current, recent, or remote pioglitazone exposure.ConclusionTZD exposure did not increase the risk of AMI when exposure proximity was not considered. However, when evaluating exposure proximity to the event, the risk of AMI was increased with recent rosiglitazone exposure between 1 and 60 days prior to the case date. Copyright © 2008 John Wiley & Sons, Ltd.
The results of performance measurements of field‐aged crystalline silicon photovoltaic modules
Authors: Skoczek Artur , Sample Tony , Dunlop Ewan D. 
Published: December 2008

AbstractThis paper presents the results of electrical performance measurements of 204 crystalline silicon‐wafer based photovoltaic modules following long‐term continuous outdoor exposure. The modules comprise a set of 53 module types originating from 20 different producers, all of which were originally characterized at the European Solar Test Installation (ESTI), over the period 1982–1986. The modules represent diverse generations of PV technologies, different encapsulation and substrate materials. The modules electrical performance was determined according to the standards IEC 60891 and the IEC 60904 series, electrical insulation tests were performed according to the recent IEC 61215 edition 2. Many manufacturers currently give a double power warranty for their products, typically 90% of the initial maximum power after 10 years and 80% of the original maximum power after 25 years. Applying the same criteria (taking into account modules electrical performance only and assuming 2·5% measurement uncertainty of a testing lab) only 17·6% of modules failed (35 modules out of 204 tested). Remarkably even if we consider the initial warranty period i.e. 10% of Pmaxafter 10 years, more than 65·7% of modules exposed for 20 years exceed this criteria. The definition of life time is a difficult task as there does not yet appear to be a fixed catastrophic failure point in module ageing but more of a gradual degradation. Therefore, if a system continues to produce energy which satisfies the user need it has not yet reached its end of life. If we consider this level arbitrarily to be the 80% of initial power then all indications from the measurements and observations made in this paper are that the useful lifetime of solar modules is not limited to the commonly assumed 20 year. Copyright © 2008 John Wiley & Sons, Ltd.
Performance of a mesoscale liquid fuel‐film combustion‐driven TPV power system
Authors: Li Yueh‐Heng , Lien Yung‐Sheng , Chao Yei‐Chin , Dunn‐Rankin Derek 
Published: December 2008

AbstractCombustion‐driven thermophotovoltaic (TPV) systems have obtained increasing attention in recent decades, but most studies have focused on developing narrowband photovoltaic cells and selective emitters. In terms of the heat source, conventional combustion configurations and light gaseous fuels are extensively utilized in macro‐ or meso‐scale TPV power systems to simplify thermal management and mechanical fabrication. As far as miniaturization is concerned, however, fuelling these systems with liquid hydrocarbons would provide inherent advantages of high energy density and low volatility. Liquid fuels also promise easy and safe fuel recharging for small‐scale power systems. In this paper, a central porous‐medium combustor was employed in a small scale TPV power system. The combustor incorporated an emitting chamber wall and a heat recuperator. The radiant efficiency and overall efficiency were compared using different liquid hydrocarbon fuels in the system. The electric output characteristics of the combustion driven TPV system have been investigated to demonstrate the feasibility of a GaSb cell‐based TPV power system and to provide design guidance for mesoscale liquid‐burning TPV systems. Copyright © 2008 John Wiley & Sons, Ltd.
Approach to peptide decorated micelles via RAFT polymerization
Authors: Liu Jingquan , Liu Huiyun , Boyer Cyrille , Bulmus Volga , Davis Thomas P. 
Published: December 2008

AbstractPyridyldisulfide (PDS) functionalized telechelic polymers of oligo(ethyleneglycol) acrylate (PEG‐A) and their amphiphilic triblock copolymers with styrene (St) were synthesized directly by reversible addition‐fragmentation chain transfer (RAFT) polymerization using a new bifunctional RAFT agent, S,S‐bis[α,α′‐dimethyl‐α″‐(2‐pyridyl disulfide) ethyl acetate] trithiocarbonate (BDPET). The homopolymerization of PEG‐A was found to be well controlled using BDPET (PDI < 1.2). The ABA triblock copolymers poly(PEG‐A)‐b‐poly(St)‐b‐poly(PEG‐A) with narrow molecular weight distribution (PDI < 1.25) were synthesized using poly(PEG‐A) as a macro‐RAFT agent. UV‐vis spectroscopic analysis revealed that 85 mol % of poly(PEG‐A) and 78 mol % of poly(PEG‐A)‐b‐poly(St)‐b‐poly(PEG‐A) retained PDS end group functionality. Micelles were observed to form from poly(PEG‐A)‐b‐poly(St)‐b‐poly(PEG‐A). The presence of PDS groups within the micelle corona was evidenced by UV‐vis spectroscopy and fluorescence spectroscopy. The PDS groups within the corona were then used to functionalize the micelles with a thiol group bearing model peptide, reduced glutathione, and a thiol modified fluorophore, rhodamine B, under mild reaction conditions. UV‐vis and fluorescence spectrocopies revealed that approximately 80% PDS groups from the amphiphilic copolymer were tethered within the micelle coronas and accessible to glutathione and fluorophore attachment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 899–912, 2009
Homogeneous graft copolymerization and characterization of novel artificial glycoprotein: Chitosan‐poly(L‐tryptophan) copolymers with secondary structural side chains
Authors: Xiang Yan , Si Jiangju , Zhang Qi , Liu Yang , Guo Hong 
Published: December 2008

AbstractA novel series of artificial glycoprotein, peptide‐chitosan copolymers with secondary structural side chain have been synthesized by ring‐opening polymerization of L‐tryptophan N‐carboxyanhydride under homogeneous conditions. Their chemical structures and polymerization degree (DP) were characterized by IR, 13C NMR, and XRD spectra. Distinctly secondary protein structure has been found in the poly‐L‐tryptophan side chains of copolymers and with the lengthening of side chain (i.e., the increase of DP at the same time), its conformations could transfer from β‐sheet to α‐helix. The content of α‐helix reaches about 41% when DP of polytryptophan is 22. The solubility of graft copolymers in polar solvent strongly depends on the length of poly‐L‐tryptophan side chains. Unique fluorescence emission at 360 nm has been observed in the glycopolymers and the intensity shows the positive‐correlation with the increasing of DP of polytryptophan. Importantly, the fluorescence effect can be quenched easily by the coordination with copper ions which provides the possibility on the biosensor design. In comparison with chitosan, glycopolymers also present impressively enhanced compressive strength and elastic modules when it is blended with epoxy E 44 to form epoxy‐copolymer hybrid resin. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 925–934, 2009