bluuebunny/crossref_metadata_2025_split huggingface dataset:
PI‐3K/Akt signal pathway plays a crucial role in arsenite‐induced cell proliferation of human keratinocytes through induction of cyclin D1
Authors: Ouyang Weiming , Li Jingxia , Zhang Dongyun , Jiang Bing‐Hua , Huang Dr Chuanshu 
Published: March 2007

AbstractExposure of arsenite can induce hyperproliferation of skin cells, which is believed to play important roles in arsenite‐induced carcinogenesis by affecting both promotion and progression stages. However, the signal pathways and target genes activated by arsenite exposure responsible for the proliferation remain to be defined. In the present study, we found that: (1) exposure of human keratinocytic HaCat cells to arsenite caused an increase in cell proliferation, which was significantly inhibited by pretreatment of wortmannin, a specific chemical inhibitor of PI‐3K/Akt signal pathway; (2) arsenite exposure was also able to activate PI‐3K/Akt signal pathway, which thereby induced the elevation of cyclin D1 expression level in both HaCat cells and human primary keratinocytes based on that inhibition of PI‐3K/Akt pathway by either pretreatment of wortmannin or the transfection of their dominant mutants, significantly inhibited cyclin D1 expression upon arsenite exposure; (3) PI‐3K/Akt pathway is implicated in arsenite‐induced proliferation of HaCat cells through the induction of cyclin D1 because either knockdown of cyclin D1 by its siRNA or inhibition of PI‐3K/Akt signal pathway by their dominant mutants markedly impaired the proliferation of HaCat cells induced by arsenite exposure. Taken together, we provide the direct evidence that PI‐3K/Akt pathway plays a role in the regulation of cell proliferation through the induction of cyclin D1 in human keratinocytes upon arsenite treatment. Given the importance of aberrant cell proliferation in cell transformation, we propose that the activation of PI‐3K/Akt pathway and cyclin D1 induction may be the important mediators of human skin carcinogenic effect of arsenite. J. Cell. Biochem. 101: 969–978, 2007. © 2007 Wiley‐Liss, Inc.
Ear mesenchymal stem cells (EMSC) can differentiate into spontaneously contracting muscle cells
Authors: Gawronska‐Kozak Barbara , Manuel Jessica A. , Prpic Veronica 
Published: March 2007

AbstractWe have previously shown that cells isolated from the outer ears of adult mice are a source of mesenchymal stem cells that can be induced to differentiate into adipo‐, osteo‐, and chondrocytes. In this study, we demonstrate that ear mesenchymal stem cells (EMSC) express stromal cell‐associated markers (CD44, CD73) and stem cell marker Sca‐1 and can be differentiated into spontaneously contracting muscle cells. Treatment of cells with epidermal growth factor (EGF) change their morphology from fibroblast shapes into stick‐like structures that show repeated spontaneous contractions. Under conditions that promote myogenic differentiation, EMSC expressed mRNA for myoD and ventricular specific myosin light chain (MLC‐2v) and protein for connexin 43, sarcomeric α‐actinin, myocyte enhancer factor 2c (MEF2c), myosin heavy chain (MyHC), myogenin, and sarco‐endoplasmic reticulum Ca2+ATPase (SERCA) 1. However, the cells were negative for Nkx2.5, GATA4, and ANP. Intracellular Ca2+ transients in spontaneously beating EMSC, visualized by Fluo‐3AM, showed a frequency of Ca2+ oscillations ranging over 28–59/min (mean 41.17 ± SEM 1.54). We also demonstrated that small pieces of ear tissues (ear punches) collected from live mice provide sufficient numbers of EMSC to isolate, culture and differentiate them into myocytes. Due to the ease of acquiring an expanding repertoire of differentiated EMSC cell types by a noninvasive surgical procedure, we conclude that the ear may prove to be a potential source of autologous cells for regenerative medicine, as supported by the fact that ears are one of the best sources of cells for somatic cell nuclear transfer (SCNT). J. Cell. Biochem. 102: 122–135, 2007. © 2007 Wiley‐Liss, Inc.
Improving access to reproductive and child health services in developing countries: are competitive voucher schemes an option?
Authors: Bhatia M. R. , Gorter A. C. 
Published: March 2007

AbstractReducing maternal and child mortality is an important goal of the Millennium declaration and a major concern for policy makers in developing countries. One of the important barriers to reducing maternal mortality is the low utilisation of maternal health services provided by the public health system through it supply side mechanisms.Demand side financing is increasingly being proposed as one of the options to increase access to reproductive and child health services and is generating great interest in a number of developing countries. Demand side financing not only promotes equity through improved access and better targeting of subsidies, but also provides incentives for efficiency and provider choice by involving the private sector. This paper discusses the concept of demand side financing, and analyses its strengths and limitations. Copyright © 2007 John Wiley & Sons, Ltd.
Multilocular cystic nephroma: MR imaging appearance with current techniques, including gadolinium enhancement
Authors: Kettritz Ute , Semelka Richard C. , Siegelman Evan S. , Shoenut J. Patrick , Mitchell Donald G. 
Published: March 2007

AbstractThe purpose of the study was to define the MRI appearance of multilocular cystic nephroma (MLCN), using current MR techniques, including gadolinium (Gd)‐enhanced sequences. Seven patients with MLCN underwent MR imaging with the following sequences: T1‐weighted spin echo with fat suppression (TIFS, five patients), T1‐weighted spoiled gradient echo (SGE, seven patients), T2‐weighted fast spin echo (two patients), and Gd‐enhanced TIFS (seven patients) and SGE (seven patients). MLCN was histologically proven by resection of the mass in six patients and by observation of typical imaging features with stability in appearance over a 6‐month period in one patient. Lesion morphology and signal intensity (SI) features were retrospectively evaluated. MRI features of MLCN included a solitary cystic lesion with thin internal septations in six patients and a cluster of closely grouped cysts similar in size in one patient. Individual cystic spaces demonstrated SI, varying from low to high on T1‐weighted images in three patients and demonstrated low‐to‐intermediate SI in four patients. Herniation of the lesions into the renal collecting system and thin enhancing septa were demonstrated in all patients. A complex cystic renal lesion with enhancing septa and herniation into the renal collecting system are the characteristic MR findings of MLCN. The direct multiplanar capability of MR may optimally show the relationship of MLCN to the renal pelvis and, thus, facilitate correct diagnosis.
Gd‐DOTA tubular transit asymmetry induced by angiotensin‐converting enzyme inhibitor in experimental renovascular hypertension
Authors: Trillaud Hervé , Roques François , Degrèze Philippe , Combe Christian , Grenier Nicolas 
Published: March 2007

AbstractIn stenosis of a renal artery, angiotensin‐converting enzyme inhibitor (ACEI) can induce a decrease in ipsilateral glomerular filtration. Dynamic MR imaging with gadolinium chelate enhancement was tested to detect this glomerular filtration reduction in experimental renovascular hypertension in the rat. Thirteen rats, with surgically induced left renal artery stenosis, developed hypertension and were studied before and after intravenous injection of ACEI with sequential Gd‐DOTA‐enhanced MR imaging. The time to onset of the tubular phase, the time of the maximal drop of signal, and the medullary signal‐time curves of both kidneys were compared. Before ACEI, tubular phases were symmetric in 11 rats and slightly asymmetric in 2. Twelve rats showed ACEI‐induced changes (positive test): absence of tubular phase on the left side (n=8) or delay (n=4) with significant differences (P<.01). Tubular phases remained symmetric in one (negative test). Dynamic MR imaging can identify ACEI‐induced Gd‐DOTA tubular transit asymmetry, indicative of functionally significant renal artery stenoses, in rats.
Design of gradient coils for permanent magnets
Authors: Wang Jingguo , Abele Manlio G. , Rusinek Henry 
Published: March 2007

AbstractDesigning gradient coils for permanent magnets requires modeling the interaction between the currents and the ferromagnetic material. We have developed and tested an iterative design approach based on the boundary element method. The power dissipated by the gradient coil is treated as a constraint of the minimization problem. The technique is illustrated on a magnet with a rectangular prismatic cavity and two ferromagnetic plates adjacent to the coil. The procedure improved the linearity of the field from 10.5% to 3.4% and reduced the power dissipation to 63% of the power of the unoptimized coil. The optimized distribution of currents has been transformed to variable locations of coil windings without loss of gradient uniformity. The new approach significantly reduces computation time and memory storage and yields practical designs of gradient coils for permanent magnets.
Interaction between paramagnetic metal complexes and intracellular water of single cells
Authors: Päuser Sabine , Zschunke Adolf , Keller Konrad 
Published: March 2007

AbstractOocytes from Xenopus laevis were used as a well‐established model to investigate spatially resolved changes in relaxation time (T1) within a cell during exposure to copper complexes by means of 'H‐NMR‐microscopy. T1 relaxation of intracellular water was shortened in dependence on the complex concentration, the water content, and the water mobility in various cell compartments. A relatively constant T1 decrease was observed in the cytoplasm of the vegetal pole, irrespective of the type and concentration of the permeable complexes used. Since the lowest content of free mobile water molecules was detected at the vegetal pole, we concluded that this quantity was as important for the relaxation time decrease as that of the chelated paramagnetic ions. Experiments using 14C‐labeled inulin demonstrated that the paramagnetic metal complexes entered the oocytes without gross injury to their plasma membranes.
Safety of gadodiamide injection in two different age groups
Authors: Högström Barry , Kristoffersen Doris T. , Lundby Bjørg , Svaland Marit G. 
Published: March 2007

AbstractA meta‐analyses was performed to evaluate the safety of gadodiamide injection (OMNISCAN®) for magnetic resonance imaging in two different age groups (< 65 years; ≥ 65 years). Data on vital signs, clinical laboratory parameters, and subjectively experienced adverse events were reviewed for 734 patients included in 19 European Phase II and III trials with gadodiamide injection (0.1 mmol/kg body weight or 0.3 mmol/kg body weight) used in magnetic resonance imaging. One hundred sixty‐four patients were 65 years of age or older. No statistically significant differences were shown between this population and the population younger than 65 years of age with respect to vital signs or clinical laboratory parameters. A total of 48 adverse events, discomfort excluded, were reported, with no significant difference in frequency between the two age groups. Injection‐associated discomfort was significantly (P=.0025) more frequent in the younger (9.2%) than in the older group (2.5%). Gadodiamide injection is in conclusion a safe contrast medium in older as well as in younger patients.
Feasibility of overhauser‐enhanced MR imaging with nitroxide free radicals
Authors: Lee James N. 
Published: March 2007

AbstractOverhauser enhancement can increase the signal available in low‐field imaging systems. If the signal is enhanced by a factor of 40, low‐field Overhauser‐enhanced imaging may produce contrast equivalent to that achieved in subtraction MR mammography performed at 1.5 T. This article describes experiments in which Overhauser enhancement is performed with nitroxide free radicals at field strengths near 100 G. The enhanced signal is much less than 40, and less than the equilibrium signal at 0.25 T, in spite of absorbed power levels greater than 100 W/kg. Although the signal enhancement for nitroxides is disappointing, it is likely that other free radical contrast agents will be developed that offer higher Overhauser enhancement.
MR arterial portography with gadolinium‐DOTA: Analysis of nontumoral perfusion abnormalities
Authors: Soyer Philippe , Laissy Jean‐Pierre 
Published: March 2007

AbstractThe purpose of this article was to determine the frequency and imaging characteristics of nontumoral perfusion abnormalities observed on magnetic resonance imaging (MRI) obtained during arterial portography (MRAP). MRAP examinations done in 23 consecutive patients with malignant hepatic tumors were retrospectively and blindly reviewed by two readers for the presence of nontumoral perfusion abnormalities. MR images were assessed for the presence, location, shape, and type of nontumoral perfusion abnormalities, and correlated with intraoperative findings or follow‐up imaging studies. Fourteen nontumoral perfusion abnormalities were found in 10 patients (43%). Nontumoral perfusion abnormalities were categorized into these five types: triangular nontumoral perfusion defects not associated with a more proximal tumor (n = 6), triangular nontumoral perfusion abnormalities distal to a tumor (n = 2), hypoperfusion involving 1 or >1 segment (n = 2), hyperenhancement of the posterior part of the right hemiliver (n = 2), and gravity‐effect‐related perfusion abnormality (n = 2). Nontumoral perfusion abnormalities are seen frequently on MRAP examination. Recognition of these abnormalities remains crucial to avoid misdiagnosis.
Use of magnetization transfer contrast to improve single breath‐hold three‐dimensional MR‐portography with bolus injection of gadopentetate dimeglumine: A preliminary report
Authors: Suto Yuji , Kato Takashi , Kimura Toshihiko , Takizawa Osamu 
Published: March 2007

AbstractWe investigated whether better visualization of the intrahepatic portal system could be obtained by adding magnetization transfer contrast (MTC) to three‐dimensional MR portography (3D‐MRP). In 15 healthy volunteers, 3D fast low‐angle shot images combined with an off‐resonance pulse were obtained after bolus injection of gadopentetate dimeglumine during one period of breath‐holding. Within 1 week after injection, MR images without MTC were obtained using the same scanning condition. MRPs with and without the MTC pulse were compared quantitatively and qualitatively. The contrast‐to‐noise ratio of the portal vein–liver was significantly higher in the group imaged with the addition of MTC. Qualitatively, the use of MTC improved peripheral portal branch depiction on maximum‐intensity projection images. Even when the MTC pulse was added to the conventional method of 3D data collection, it was possible to obtain images within one period of breath‐holding. In conclusion, the use of MTC can substantially enhance the quality of 3D‐MRPs.
Dialysis and transplantation affect cerebral abnormalities of end‐stage renal disease
Authors: Michaelis Thomas , Videen John S. , Linsey Michael S. , Ross Brian D. 
Published: March 2007

AbstractLocalized short echo time proton magnetic resonance spectroscopy was performed to determine whether chronic and end‐stage renal failure, hemodialysis, continuous ambulatory peritoneal dialysis, or renal transplantation result in alterations of cerebral water and metabolites in humans. Hemodialysis patients show an increased cerebral concentration of myo‐inositol (+ 14%; P < .05). Increased metabolite ratios are found for myo‐inositol/creatine (+ 14%; P < .01) and choline‐containing compounds choline/creatine (+ 10%; P < .01) and are more marked in gray than in white matter. N‐acetylaspartate and total creatine concentrations are unaffected. Compared to hemodialysis, continuous ambulatory peritoneal dialysis patients show a larger increase in choline and less elevated myo‐inositol. Acutely, hemodialysis significantly decreases the cerebrospinal fluid content of the examined brain regions, but metabolite changes are small compared to the persistent alterations in patients receiving hemodialysis or continuous ambulatory peritoneal dialysis. Undialyzed patients with chronic renal failure do not differ from patients on hemodialysis, but cerebral metabolite changes are completely reversed by transplantation.Cerebral metabolic effects of end‐stage renal disease differ from Alzheimer's disease, which is associated with markedly reduced N‐acetylaspartate, increased myo‐inositol, and normal choline concentrations. The small but significant cerebral metabolic disorders associated with renal failure and dialysis may be a consequence of osmotic dysregulation.
T1‐Weighted MR imaging of the brain using a fast inversion recovery pulse sequence
Authors: Rydberg John N. , Hammond Charlotte A. , Iii John Huston , Jack Clifford R. , Grimm Roger C. , Riederer Stephen J. 
Published: March 2007

AbstractThe purpose of this paper was to develop and evaluate a fast inversion recovery (FIR) technique for T1‐weighted MR imaging of contrast‐enhancing brain pathology. The FIR technique was developed, capable of imaging 24 sections in approximately 7 minutes using two echoes per repetition and an alternating echo phase encoding assignment. Resulting images were compared with conventional T1‐weighted spin echo (T1SE) images in 18 consecutive patients. Compared with corresponding T1SE images, FIR images were quantitatively comparable or superior for lesion‐to‐background contrast and contrast‐to‐noise ratio (CNR). Gray‐to‐white matter and cerebrospinal fluid (CSF)‐to‐white matter contrast and CNR were statistically superior in FIR images. Qualitatively, the FIR technique provided comparable lesion detection, improved lesion conspicuity, and superior image contrast compared with T1SE images. Although FIR images had greater amounts of image artifacts, there was not a statistically increased amount of interpretation‐interfering image artifact. FIR provides T1‐weighted images that are superior to T1SE images for a number of image quality criteria.
Magnetic resonance imaging of the brain: Blood partition coefficient for water: Application to spin‐tagging measurement of perfusion
Authors: Roberts David A. , Rizi Rahim , Lenkinski Robert E. , Leigh John S. 
Published: March 2007

AbstractWe describe the use of relative proton density imaging to obtain spatially resolved measurements of the brain:blood partition coefficient for water. Values of relative proton density and apparent‐T1 were calculated by performing a multidimensional nonlinear least squares fit of progressive saturation image data. Correction for magnetic field inhomogeneity was included. The partition coefficient was calculated by dividing the relative proton density of brain by the relative proton density of blood water. Results obtained from healthy volunteers demonstrate significant spatial variation in the partition coefficient in brain. Direct measurement of this parameter eliminates a source of error in the calculation of regional perfusion using arterial spin‐tagging techniques.
Line scan imaging of brain metabolites with CPMG sequences at 1.5 tesla
Authors: Mulkern Robert V. , Meng Jiqun , Oshio Koichi , Tzika A. Aria 
Published: March 2007

AbstractA line scan Carr‐Purcell‐Meiboom‐Gill (CPMG) spectroscopic imaging sequence has been implemented on a standard 1.5 T clinical scanner to map metabolite signals at multiple echo times from voxels along selected tissue columns through the brain. The CPMG multi‐echo spectroscopic image data sets are used to estimate brain metabolite T2 decay parameters in a group of healthy volunteers and in one tumor patient. Inherent trade‐offs between T2 decay, spectral resolution, and echo spacing prove to be important limiting factors. In particular, separate quantitation of choline and creatine resonances at 1.5 T was not achieved in the present implementation. However, the ability to collect data sets suitable for T2 decay analyses of combined choline and creatine resonances and N‐acetyl aspartate resonances in under 10 minutes may prove of clinical utility in the study of brain pathology.
Effects of intravoxel velocity distributions on the complex difference method of phase‐contrast MR angiography
Authors: Hamilton Craig A. 
Published: March 2007

AbstractThe complex difference method of phase‐contrast MR angiography is affected not only by the degree of velocity encoding applied during the scan but also by the variance of the intravoxel velocity distribution. The reconstructed intensities of voxels with the same average flow rate but different variances of the velocity distribution can differ significantly. Mathematical analysis and scanner phantom experiments confirm this conclusion.
Magnetic resonance imaging of the brain with gadopentetate dimeglumine‐DTPA: Comparison of T1‐weighted spin‐echo and 3D gradient‐echo sequences
Authors: Li Debiao , Haacke E. Mark , Tarr Robert W. , Venkatesan Ramesh , Lin Weili , Wielopolski Piotr 
Published: March 2007

AbstractShort TR, short TE, high resolution, 3D gradient‐recalled echo (GRE) imaging was evaluated for lesion detection in the brain. High resolution 3D GRE data acquisition was used to reduce partial volume effects and flow artifacts, to better visualize smaller structures, to minimize signal losses caused by field inhomogeneities, and to allow better image reformatting. Spin‐echo (SE) and 3D GRE approaches were compared for lesion detection after the administration of an MR contrast agent, gadopentetate dimeglumine. Preliminary clinical studies demonstrated that the signal‐to‐noise ratio (SNR) in each slice of the GRE scan was worse than that of the SE scan because of the much thicker slices acquired with the SE technique. However, by averaging two adjacent 3D slices, the SNR of the two methods was essentially equivalent. In the averaged GRE slices, large lesions were seen just as well as in the SE images. More importantly, small lesions were better visualized in the thin 3D GRE images than in the thick SE images for the lesions studied in this work and the protocols used. These observations were confirmed by theoretical simulations.
Classification of 1H MR spectra of human brain neoplasms: The influence of preprocessing and computerized consensus diagnosis on classification accuracy
Authors: Somorjai Ray L. , Dolenko Brion , Nikulin Alexander K. , Pizzi Nicolino , Scarth Gordon , Zhilkin Peter , Halliday William , Fewer Derek , Hill Norman , Ross Ian , West Michael , Smith Ian C. P. , Donnelly S. Maureen , Kuesel Annette C. , Brière Kathleen M. 
Published: March 2007

AbstractWe study how classification accuracy can be improved when both different data preprocessing methods and computerized consensus diagnosis (CCD) are applied to 1H magnetic resonance (MR) spectra of astrocytomas, meningiomas, and epileptic brain tissue. The MR spectra (360 MHz, 37°C) of tissue specimens (biopsies) from subjects with meningiomas (95; 26 cases), astrocytomas (74; 26 cases), and epilepsy (37; 8 cases) were preprocessed by several methods. Each data set was partitioned into training and validation sets. Robust classification was carried out via linear discriminant analysis (LDA), artificial neural nets (NN), and CCD, and the results were compared with histopathological diagnosis of the MR specimens. Normalization of the relevant spectral regions affects classification accuracy significantly. The spectra‐based average three‐class classification accuracies of LDA and NN increased from 81.7% (unnormalized data sets) to 89.9% (normalized). CCD increased the classification accuracy of the normalized sets to an average of 91.8%. CCD invariably decreases the fraction of unclassifiable spectra. The same trends prevail, with improved results, for casebased classification. Preprocessing the 1H MR spectra is essential for accurate and reliable classification of astrocytomas, meningiomas, and nontumorous epileptic brain tissue. CCD improves classification accuracy, with an attendant decrease in the fraction of unclassifiable spectra or cases.