bluuebunny/crossref_metadata_2025_split huggingface dataset:
Development of a mouse aortic transplant model of chronic rejection
Authors: Koulack Joshua , McAlister Vivian C. , Giacomantonio Carman A. , Bitter‐Suermann Hinrich , McAdonald Allan S. , Lee Timothy D. G. 
Published: March 2007

AbstractChronic rejection is the most common cause of late graft failure after solid organ transplantation. A model of chronic rejection, the rat aortic allograft, has histologic features that parallel those in the vessels of human transplanted organs. However, the molecular tools required to dissect the immunology of chronic rejection are unavailable in the rat. We developed aortic transplantation in the mouse as a new model of chronic rejection. This will allow the use of the diversity of recombinant cytokines and monoclonal antibodies available for the mouse and its well‐defined genetics to investigate chronic rejection in greater detail. We describe the perioperative care and surgical technique for the model in which a 1 cm segment of donor thoracic aorta was used to replace a section of recipient abdominal aorta below the renal arteries and above the aortic bifurcation. Mortality rates were initially high (70%) due to thrombosis and shock. Changes in technique and operator facility resulted in a high rate of success (75%). After 192 operations, the current success rate is >80%. Mice free from complications at 12 hrs postop had indefinite survival, and after 2 months the typical vascular lesion of chronic rejection was present. This new model of chronic rejection will be a valuable tool to study the molecular immunology and genetics of chronic rejection. © 1995 Wiley‐Liss, Inc.
Clinical use of microvascular PTFE grafts
Authors: Lanzetta Marco 
Published: March 2007

AbstractThis paper reports on the first clinical case where a polytetrafluoroethylene (PTFE) graft of less than 3 mm in diameter was implanted in the arterial system of a patient to bridge a vascular defect. A 1.5 cm long, 1.5 mm diameter prosthesis was interposed in the superficial palmar arch of a man who sustained a laceration of the palm of his dominant hand. The graft was implanted by means of the 3M Precise Microvascular Anastomotic System on one end, and by conventional microsurgical technique on the other end. There were no postoperative complications. The patient resumed his preinjury activities 9 weeks after trauma. Serial Doppler ultrasound examinations showed normal blood flow and complete patency of the graft. An angiogram performed 12 weeks postoperatively confirmed the patency of the prosthesis. Twelve months post‐operatively the patient is free from complications. The use of small diameter PTFE prostheses may be considered when planning grafting procedures for microvascular defects. © 1995 Wiley‐Liss, Inc.
Comparison of nylon and polypropylene sutures in a microvenous thrombosis model
Authors: Üstüner Tuncay E. , Zhang Feng , Lineaweaver William C. 
Published: March 2007

AbstractThrombosis rates of femoral end‐to‐end microvenous anastomoses with nylon and polypropylene sutures (9–0 suture, 70 μ needle) were compared in a microvenous thrombosis model. The vessel injuries were produced during anastomosis by using a suture with a knot 1 cm from the needle. Anastomotic thrombosis rates were assessed by visual inspection and strip test at 24 hr postoperatively. Low thrombosis rates (0% and 20%, respectively) of anastomoses with both unknotted nylon and unknotted polypropylene sutures were obtained. Anastomoses with knotted nylon and polypropylene sutures resulted in 65% and 45% thrombosis rates, respectively. Statistical analyses showed that there were no significant differences between thrombosis rates, both in anastomosis performance with unknotted nylon and polypropylene sutures (P > 0.05) and with knotted nylon and polypropylene sutures (P > 0.05), while there were significant differences between the thrombosis rate using unknotted sutures and knotted sutures (P<0.01). It was concluded that vascular injury, not suture material, is the main factor leading to thrombosis in this model. © 1995 Wiley‐Liss, Inc.
Application of sciatic functional index in nerve functional assessment
Authors: Shen Ninjiang , Zhu Jiakai 
Published: March 2007

AbstractIn order to confirm the reliability of the sciatic functional index (SFI) in the rat, SFI, muscle strength, electrophysiological, and morphometric assessments were carried out from the 10th day to the sixth month after nerve injury or repair. The results showed that the SFI has a positive correlation with all tested indices of muscle strength, electrophysiology and morphology (r = 0.925–0.996, P<0.01 or P<0.001). These results indicate that the SFI is a reliable index for evaluating rat sciatic nerve regeneration and can be widely used. © 1995 Wiley‐Liss, Inc.
Comparison of the telescoping anastomotic technique with the end‐to‐end technique utilizing vein grafts for venous defects: Short‐ and long‐term results
Authors: Saitoh Satoru , Kitagawa Eiji , Nakatsuchi Yukio 
Published: March 2007

AbstractThe telescoping anastomotic technique was used for both anastomoses of vein grafts placed in the rat left epigastric vein in an effort to make the anastomosis easier and faster. Vein grafting in the right epigastric vein was completed using the conventional technique. The 20 rats with 20 left and 13 right vein grafts, which were patent at 3 weeks, were seen again 3 months postoperatively to compare the two techniques with regard to long‐term stenosis and histological changes. Patency of the grafts 2 hr postoperatively was also compared between the two techniques in another 25 rats to eliminate the influence of recanalization on patency. All the vein grafts, which had been patent 3 weeks postoperatively, remained patent after 3 months and no statistically significant difference was found between the telescoping and conventional technique in the degree of stenosis. The vein grafts 2 hr postoperatively were all patent in both groups. © 1995 Wiley‐Liss, Inc.
Effects of the flavonoid biochanin A on gene expression in primary human hepatocytes and human intestinal cells
Authors: Moon Young Jin , Zhang Shuzhong , Brazeau Daniel A. , Morris Marilyn E. 
Published: March 2007

AbstractBiochanin A (BCA), a phytoestrogen present in plant food and herbal products, has been reported to have cancer‐preventive effects that may be mediated, in part, through effects on carcinogen metabolism. Our objective was to examine the effect of BCA on gene expression for drug‐metabolizing enzymes and transporters in human hepatocytes. Cells were exposed to 20 μM of BCA for 5 days. Gene expression was assessed by a 96‐gene human drug metabolism enzyme microarray. There were seven genes that were significantly up‐regulated, namely cytochrome P‐450 (CYP) 2A6, CYP2B6, CYP2C9, CYP2F1, multidrug resistance gene (MDR1), thromboxane A synthase 1 (TBXAS1), and SULT1A2 (sulfotransferase). Up‐regulation of MDR1, which encodes for P‐glycoprotein, was confirmed using real‐time RT‐PCR and Western analysis in hepatocytes as well as in human colon adenocarcinoma cell line (LS‐180) and the induction was dose‐dependent. BCA treatment up‐regulated genes mainly in the CYP2 family. This induction can influence the metabolism of xenobiotics, producing effects of pharmacological and toxicological importance.
Signal to Noise in Derived NMR Images
Authors: Ortendahl Douglas A. , Hylton Nola M. , Kaufman Leon , Crooks Lawrence E. 
Published: March 2007

AbstractThe NMR image is dependent on multiple tissue parameters: hydrogen density, relaxation times T1 and T2, and flow. From the acquired intensity images, T1, T2, and hydrogen images may be produced. The signal/noise of these derived images is critically dependent on the choice of acquisition parameters. Using the calculated T1, T2, and hydrogen images, intensity images may be calculated at arbitrary values of TE and TR, some of which (for example, short TE or TR) may be physically unacquirable.
Quadrature detection in the laboratory frame
Authors: Hoult D. I. , Chen C.‐N. , Sank V. J. 
Published: March 2007

AbstractA theory of quadrature detection in the laboratory frame is developed. It is shown that the geometry of the two orthogonal coil systems needed for quadrature detection is radically different from that used with saddle‐shaped coils, and that the homogeneity of the B1 field produced upon transmission is marginally better. The opposing quadrature phase shifts needed for transmission and reception are emphasized, and the use of a quadrature hybrid is advocated as a simple and inexpensive means of interfacing the transmitter, probes, and preamplifier. Experimental results are presented which confirm the theoretical predictions, and show that up to a 40% improvement in sensitivity and a twofold reduction in transmitter power are possible, particularly in those instances where the sample is conductive—namely, imaging of humans and in vivo spectroscopy.
Magnetic field dependence of solvent proton relaxation induced by Gd3+ and Mn2+ complexes
Authors: Koenig Seymour H. , Baglin Coral , Brown Rodney D. , Fred Brewer C. 
Published: March 2007

AbstractThe effect of solute paramagnetic ions on the longitudinal magnetic relaxation rate 1/T1 of solvent water protons depends on magnetic field strength and on the chemical environment of the ions. The variation of 1/T1 with field has been measured for solutions of Gd3+ and Mn2+ ions in three grossly different environments near physiological pH: the hydrated aquoion; chelated by EDTA (ethylenediaminetetraacetic acid) and DTPA (diethylenetriaminepentaacetic acid); and bound to the protein concanavalin A. It is demonstrated that over the field range at which NMR imaging is currently being done, the chemical environment can alter 1/T1 of solvent protons by more than an order of magnitude. The relevance of these results to the potential utility of these ions as agents for enhancement of contrast in NMR images is discussed.
Application of linear prediction and singular value decomposition (LPSVD) to determine NMR frequencies and intensities from the FID
Authors: Barkhuijsen H. , De Beer R. , Bovee W. M. M. J. , Creyghton J. H. N. , Van Ormondt D. 
Published: March 2007

AbstractA parametric spectral analysis based on linear prediction and singular value decomposition has been applied to the 31P FID of a tumor implanted in a mouse. It is found that a number of complications that may arise in in vivo FFT NMR can be circumvented. The new method yields all parameters of the spectral components, i. e., the frequency, amplitude, damping constant, and phase.
Fast fourier imaging
Authors: Uijen C. M. J. Van , Boef J. H. Den , Verschuren F. J. J. 
Published: March 2007

AbstractA new NMR imaging technique, aiming at a reduction of the data acquisition time, is described in detail. The method is applicable in all multidimensional imaging situations where at least one spatial coordinate is resolved. Discussed at some length are the point‐spread function, the requird bandwidth of the NMR spectrometer, and the sampling strategy used to diminish the loss in signal‐to‐noise ratio. Experiments reveal that a reduction of the data acquisition time by at least a factor of four is attainable in practice.
31P Spin‐Lattice Relaxation Times and Resonance Linewidths of Rat Tissue in Vivo: Dependence upon the Static Magnetic Field Strength
Authors: Evelhoch Jeffrey L. , Ewy Coleen S. , Siegfried Barry A. , Ackerman Joseph J. H. , Rice David W. , Briggs Richard W. 
Published: March 2007

AbstractPhosphorus‐31 NMR spin‐lattice relaxation times and resonance linewidths of rat leg muscle, brain, and liver metabolites in vivo have been examined at 1.9‐, 4.7‐, and 8.5‐ T static magnetic field strengths. The resonance linewidths expressed in ppm that have been measured are independent of field strength. The spin‐lattice relaxation times of muscle and brain phosphorus metabolites decrease linearly with increasing field strength while those of liver are constant over the range of static fields examined.
Chemical‐Shift Magnetic Resonance Imaging of Two‐Line Spectra by Gradient Reversal
Authors: Axel Leon , Glover Gary , Pelc Norbert 
Published: March 2007

AbstractA method of chemical‐shift imaging is described using the invariance of chemical shifts to changes in magnetic field gradients used for frequency encoding of position in imaging. This enables separation of the effects on the observed signal of chemical shift from the effects of different positions along the imaging gradient when the signal is observed with different gradients. A simple implementation for a two‐line spectrum is presented using signals observed with normal and reversed imaging gradients. This is used to create “fat” and “water” images of the thigh.© 1985 Academic Press,Inc.
Chemical‐Shift Imaging
Authors: Guilfoyle D. N. , Mansfield P. 
Published: March 2007

AbstractThe echo‐planar shift mapping (EPSM) technique, a variant of echo‐planar imaging (EPI), is evaluated with theoretical studies using computer simulations and with experimental studies using fluorine resonances in phantoms. In situations where the signal‐to‐noise ratio permits, it is shown that EPSM can produce in a few seconds chemical‐shift spectra at all points in a specified spin‐density image corresponding to a selected slice. Applications of this technique are likely to be for proton and fluorine chemical‐shift measurements and rapid studies of magnetic field inhomogeneities produced by magnet nonalignment and field shifts around magnetic materials.© 1985 Academic Press,Inc.© 1985 Academic Press,Inc.
An Improved Saddle Coil for MR Imaging in Resistive Magnet Systems
Authors: Doornbos Johannes , Booijen Paul E. , Grimbergen Harry A. A. , Falke Theo H. M. 
Published: March 2007

AbstractThe design of a two‐turn radiofrequency coil for MR imaging at 0.15 T is presented. The use of well‐isolated copper tube (instead of the usual wire) as conductor material resulted in an open, patient friendly construction. Furthermore, the Q value and signalto‐noise ratio of the tube‐type coil were increased as compared to the corresponding values in the case of a geometrically similar wire‐type coil.© 1985 Academic Press,Inc.
Phase Alterations of Spin Echoes by Motion along Magnetic Field Gradients
Authors: Wendt III Richard E. , Murphy Paul H. , Ford Joseph J. , Bryan R. Nick , Burdine John A. 
Published: March 2007

AbstractUsing a Taylor series expansion of the phase shift of a moving isochromatic spin group in the presence of a magnetic field gradient, the refocusing effects of the Carr‐Purcell‐Meiboom‐Gill pulse sequence on stationary nuclei and those with constant, rectilinear velocity are readily demonstrated. Continuing the analysis to higher orders of motion reveals that nuclei with a constant, rectilinear acceleration have a phase shift at the spin echoes which increases linearly with echo number. Constant, rectilinear jerk (the time rate of change of acceleration) leads to an increase in phase shift from echo to echo which is quadratic in nature with an overlying reduction of the odd‐numbered echoes by a constant amount. Motion parameters may be measured by parameter identification techniques. These principles may be applied to phase‐sensitive NMR imaging.© 1985 Academic Press,Inc.
Magnetic Resonance Imaging the Velocity Vector Components of Fluid Flow
Authors: Feinberg David A. , Crooks Lawrence E. , Sheldon Phillip , Iii John Hoenninger , Watts Jeffrey , Arakawa Mitsuaki 
Published: March 2007

AbstractEncoding the Precession phase angle of proton nuclei for Fourier analysis has produced accurate measurement of fluid velocity vector components by MRI. A Pair of identical gradient pulses separated in time by exactly ½ TE, are used to linearly encode the phase of flow velocity vector components without changing the phase of stationary nuclei, Two‐dimensional Fourier transformation of signals gave velocity density images of laminar flow in angled tubes which were in agreement with the laws of vector addition. These Velocity profile images provide a quantitative method for the investigation of fluid dynamics and hemodynamics.© 1985 Academic Press,Inc.
Hepatic gluconeogenesis from alanine: 13C nuclear magnetic resonance methodology for in vivo studies
Authors: Stromski M. E. , Arias‐Mendoza F. , Alger J. R. , Shulman R. G. 
Published: March 2007

AbstractThis paper describes an experimental protocol designed to optimize 13C NMR spectra from the liver of the living anesthetized rat at 1.9 T. The protocol involves the use of a Helmholtz NMR coil which is positioned around the liver after surgical exposure. 1H decoupling is facilitated by double tuning this coil to both the 1H and the 13C frequencies. The protocol was shown to be suitable for studying the hepatic metabolism of 13C‐labeled substrates in vivo by investigating the metabolism of [3‐13C] alanine. Labeled glucose, glutamate, glutamine, and aspartate were formed and detected by 13C NMR in vivo in this experiment. The labeling patterns in these metabolites provided evidence that the major flow of alanine carbon into the Krebs cycle is via the pyruvate carboxylase reaction rather than through pyruvate dehydrogenase. © 1986 Academic Press, Inc.
Suppression of water and other noncoupled spins by homonuclear polarization transfer in magnetic resonance imaging
Authors: Dumoulin Charles L. 
Published: March 2007

AbstractThe water component of an NMR image is suppressed by selectively detecting only those protons which are coupled to other protons. Selectivity is obtained by polarization transfer between the coupled spins. Since spin‐spin coupling is independent of magnetic field strength, the suppression obtainable by polarization transfer is independent of chemical shift. Consequently, this technique does not require extremely homogeneous magnetic field for the separation of water and lipid signals. In addition, water suppression by this technique is independent of T1 and T2. Suppression of the water signal intensity has been observed experimentally to be as high as a factor of 100. Suppression is limited only by instrumental imperfections. © 1986 Academic Press, Inc.
Quadrature‐multiplexed rf excitation for information doubling in NMR imaging
Authors: Ra J. B. , Hilal S. K. , Cho Z. H. , Park H. W. , Cho M. H. 
Published: March 2007

AbstractA quadrature multiplexed pulse sequence to double the data information in a given acquisition time is proposed for NMR tomography. This technique takes advantage of the Hermitian property of the Fourier transform operation in NMR imaging. The proposed technique uses two rf pulses with 90° phase difference simultaneously applied for the excitation of the spins in two different slices. The method results in truly simulaneous data acquisition coming from two different anatomical slices which can be separated into the real and imaginary parts of the image domain. This technique, therefore, also allows us either to reduce the experiment time by half or double the number of slices in the same examination time, depending on the applied imaging scheme. As a preliminary study, simultancous dual‐slice imaging of a human head using a conventional single‐slice imaging scheme was performed. © 1986 Academic Press, Inc.
A modified saturation‐recovery approximation for multiple spin‐echo pulse sequences
Authors: Lee James N. , Riederer Stephen J. 
Published: March 2007

AbstractIn equations describing multiple spin‐echo pulse sequences, the T1 dependence is often approximated by a saturation‐recovery expression, which is valid only when the repetition time TR is much greater than the time required for the echoes. A slight modification of this approximation greatly increases its accuracy for small TR values. © 1986 Academic Press, Inc.
Spin‐lattice relaxation (T1) times of cerebral white matter in multiple sclerosis
Authors: Lacomis David , Osbakken Mary , Gross George 
Published: March 2007

AbstractMagnetic resonance imaging was used to evaluate the cerebral white matter of three subject groups: (1) 22 patients with known multiple sclerosis (MS) (11 with disease of shorter duration (0–5 years) and 11 with disease of longer duration (>5 years)); (2) 9 patients with suspected MS; and (3) 12 normal volunteers. Transverse spin‐echo (SE) 30/ 500 and 120/1000 radiofrequency pulse sequences were used for anatomic localization and plaque identification, respectively, while combined spin echo‐inversion recovery was used for T1 determination. T1 values were calculated for grossly normal cerebral white matter in the frontal, parietal, and occipital lobes of normal volunteers and MS patients, and for plaques in MS patients. When compared with normals, the T1 values of plaquefree areas from definite MS patients (shorter and longer duration disease groups combined) were significantly longer in the frontal lobe (MS = 374 ± 34 ms, Normal = 352 ± 39 ms, P < 0.05) and in the occipital lobe (MS = 414 ± 37, Normal = 378 ± 40, P < 0.02). Although the T1 values of the shorter duration MS group were longer than those of normals, the difference was not statistically significant. Thus, the significant difference between the definite MS group (both shorter and longer duration) is more heavily weighted by the longer duration MS group. T1 values in patients with suspected MS without plaques were not significantly different from those of normals. In diagnosed MS patients, T1 values of plaques were significantly longer than T1 values of corresponding normal areas (P < 0.05). In conclusion, plaque‐free white matter in patients with clinically diagnosed MS has longer T1 values than white matter in normals, suggesting the presence of biophysical abnormalities which are not seen on other routine imaging modalities. These differences may be accentuated as the disease progresses. Thus, it may be possible in the future to evaluate MS disease activity based on T1 characteristics of normal appearing white matter. © 1986 Academic Press, Inc.
Monoclonal antibodies labeled with polymeric paramagnetic ion chelates
Authors: Shreve Paul , Aisen Alex M. 
Published: March 2007

AbstractPolymeric paramagnetic ion chelate molecules were synthesized and covalently linked to monoclonal antibodies. The labeled antibodies retained their antigen binding capacity in vitro while carrying up to an average of 50 paramagnetic ion chelates, enabling specifically bound antibody concentrations less than 2.0 μM to significantly reduce proton longitudinal relaxation times. © 1986 Academic Press, Inc.
A computer simulation of nuclear magnetic resonance imaging
Authors: Summers Ronald M. , Axel Leon , Israel Solomon 
Published: March 2007

AbstractA modular, user‐friendly computer simulation of NMR imaging was created for the DEC VAX computer. This simulation is novel in that complex imaging phenomena, such as chemical shifts and flow, may be easily studied. Other features include spin warp and backprojection imaging, movie generation, and simulation of image contrast, composite pulse sequences, motion artifacts, aliasing, selective excitation, field inhomogeneity, noise and signal averaging. The simulation incorporates fast Fourier transform and graphics modules for processing and display of one‐and two‐dimensional images. Examples which illustrate features of the program are shown. The simulation is a useful tool for both the sophisticated and the beginning user of NMR imaging. It serves as a drawing board for studying MRI phenomena and a teaching program for demonstrating basic techniques. © 1986 Academic Press, Inc.