bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sympathetic blockade of isolated rat hindlimbs by intra‐arterial guanethidine: The effect on blood flow and arterial‐venous shunting
Authors: McCarty Michael E. , Grossi Eugene A. , Cutting Court , Prevel Christopher D. , Elluru Raguram , Eppley Barry L. 
Published: March 2007

AbstractIn order to improve the understanding of the role of sympathetic nerve degeneration in reimplantation failure, the hindlimbs of eight rats (Group I) underwent near‐complete amputation. The soft tissues of the hindlimb were transected at the proximal thigh with the femoral artery, vein and femur left intact. The femoral vessels were clamped and guanethidine was infused into a branch of the femoral artery of the right leg of each animal, while saline was injected into the left leg. The clamps were removed after 15 minutes. A baseline preoperative injection of radiolabeled microspheres was made, and subsequent injections at 6, 12, 18, and 24 hours postoperation. Twelve rats (Group II) were then used to assess the amount of arterial‐venous shunting preoperatively (n = 6) and at 18 hours postoperation (n = 6), by venous sampling. Blood flow to both limbs increased postoperation, but there was significantly more flow in the guanethidine treated limb at 18 and 24 hours postoperation. The amount of shunting was approximately 50% in both limbs at 18 hours, as compared to 10% preoperation. These results highlight the potential benefit of guanethidine and other sympathetic blocking agents in reimplantation to increase blood flow, decrease tissue ischemia and increase anastomotic patency rates. They also suggest that sympathetic nerve degeneration did not affect the volume of arterial‐venous shunting in this model, but the difference in blood flow was likely due to arteriolar vasospasm. Further study is needed to elucidate the clinical significance of sympathetic nerve degeneration in reimplantation failure. © 1995 Wiley‐Liss, Inc.
Modified crush‐avulsion anastomosis model on the rat femoral vein
Authors: Fu Kaiding , Izquierdo Ricardo , Hubbard Thomas , Fareed Jawed 
Published: March 2007

AbstractA crush‐avulsion anastomosis model was established on the rat femoral vein. Saline or heparin was used as a luminal topical agent and was allowed to contact the damaged endothelium for 10 min. Patency and coagulation parameters were investigated for 1 week. The heparin treated group had a patency rate of 93% at 1 hr vs. 13% for the saline treated group (P<0.001). At 7 days, the heparin treated group had an 87% patency vs. 7% for the saline‐treated group (P<0.001). Scanning electron micrography (SEM) provided evidence of the deposition of the components of early thrombosis in the crushed venous wall. In contrast, the SEM of the heparin treated group shows a paucity of any evidence of thrombus. These results indicate that the rat vein crush‐avulsion model is a reliable and reproducible thrombosis model with low patency. The methods used with the topical agent may improve the patency rate in crush avulsion injuries. © 1995 Wiley‐Liss, Inc.
Aneurysms of the digital artery: A review and report of three cases
Authors: Yajima Hiroshi , Tamai Susumu , Ono Hiroshi 
Published: March 2007

AbstractAneurysms of the digital artery are rare. Since 1980, we have treated three traumatic aneurysms of the digital artery. There were two lesions of the common palmar digital artery and one of the ulnar pollicis artery. One case was caused by a traumatic laceration with a kitchen knife, and two cases were caused by repetitive microtrauma. On histologic examination, there were two true aneurysms and one false aneurysm. Two cases were treated by excision only, and one case was treated by excision and reanastomosis. The operating microscope was useful during neurolysis, excision of the aneurysm, and vascular anastomosis. © 1995 Wiley‐Liss, Inc.
Evaluation of the effectiveness of sensory reeducation following digital replantation and revascularization
Authors: Shieh Shyh‐Jou , Chiu Haw‐Yen , Lee Jing‐Wei , Hsu Hsiu‐Yun 
Published: March 2007

AbstractSensory recovery following digital replantation plays an important role in the restoration of hand function. Twelve patients with twenty‐four replanted or revascularized digits were randomly selected to enter a program of sensory reeducation, and another 15 patients with 22 replanted or revascularized digits were selected as controls who did not receive sensory reeducation. A moving two‐point discrimination and a Semmes‐Weinstein pressure threshold test were evaluated for monitoring the sensory recovery. The period of sensory reeducation was 18.83 weeks on average, and the mean follow‐up time was 11.94 months. The group that received sensory reeducation significantly improved to a better degree of moving two‐point discrimination and Semmes‐Weinstein threshold level by both univariate and multiple regression analysis. We suggest that sensory reeducation should be an integral part of the postoperative rehabilitation protocol following digital replantation and revascularization. © 1995 Wiley‐Liss, Inc.
Immunosuppressive effect of monoclonal antibodies to ICAM‐1 and LFA‐1 on peripheral nerve allograft in mice
Authors: Nakao Yasushi , Mackinnon Susan E. , Strasberg Suzanne R. , Hertl M. Catherine , Isobe Mitsuaki , Susskind Brian M. , Mohanakumar T. , Hunter Daniel A. 
Published: March 2007

AbstractThis study evaluated the immunosuppressive effect of monoclonal antibodies against cell surface molecules in a murine peripheral nerve allograft model. After nerve allografting, 18 recipients were treated with both anti‐intercellular adhesion molecule‐1 (ICAM‐1) and anti‐lymphocyte function‐associated molecule‐1 (LFA‐1) monoclonal antibodies in low or high dose. Nerve allografts were harvested at 8 weeks for histologic and morphometric evaluation. Recipients were subsequently challenged with skin grafts at 9 weeks and a cytotoxic assay at 12 weeks. The majority of the antibody‐treated allografts (13 of 18) showed excellent regeneration comparable to the autografts with preservation of the normal nerve architecture and scant cellular infiltrate. All untreated allografts demonstrated severe structural disorganization with cellular infiltrate consistent with acute rejection. In the high dose group, the mean skin graft survival time from nerve donor mice, but not third‐party mice, was significantly prolonged. (17.5 vs. 11.3 days). Similarly, the cytotoxic activity against nerve donor alloantigen was significantly suppressed. These preliminary findings suggest that antibody therapy alone can facilitate nerve regeneration in a murine nerve allograft model. © 1995 Wiley‐Liss, Inc.
Nerve regeneration in different types of grafts: Experimental Study in Rabbits
Authors: Amillo Santiago , Yáñez Roberto , Barrios Raúl H. 
Published: March 2007

AbstractThe nerve regeneration patterns of five different types of grafts were studied in 40 rabbits. Conventional nerve autografts, vascularized nerve autografts, fresh nerve allografts, frozen nerve allografts, and muscle autografts were sutured to a 1.5 cm gap in the sciatic nerve and compared with normal nerves and nerves with a 3 cm gap. Regeneration was evaluated by means of electromyography, light and electron microscopy. Quantitative data from morphometric analysis of axonal diameter and myelination were statistical‐lyanalyzed. Results 5 months after grafting showed no significant differences between the conventional and vascularized nerve autografts. There were no significant differences between frozen nerve allografts and muscle autografts. The best regeneration was achieved with autografts. © 1995 Wiley‐Liss, Inc.
The NMR diagnosis of cerebral tumors
Authors: Bydder G. M. , Pennock J. M. , Steiner R. E. , Orr J. S. , Bailes D. R. , Young I. R. 
Published: March 2007

AbstractThe results of NMR examinations in 52 patients with histological or clinical diagnoses of cerebral tumor are reviewed. An increase in relaxation time was recognized in all tumors but problems were experienced in distinguishing the margin of tumors from surrounding edema. Mass effects were well demonstrated as a result of the high level of gray‐white matter contrast available with inversion‐recovery sequences and the use of coronal and sagittal imaging planes. In general repeated FID sequences were less sensitive in detecting tumors than inversion‐recovery or spin‐echo squences. Periventricular edema was well demonstrated with spin‐echo sequences and was of importance in recognizing acute or subacute hydrocephalus. Radiation therapy was associated with increased relaxation times particularly within white matter. Problems in the recognition of tumor recurrence following treatment are outlined. The opportunities and challenges that NMR imaging is now providing for physicists and radiologists are discussed.Contents. Introduction. Patients and methods. Results Normal appearances. Benign tumors. Malignant tumors. Diagnostic features of tumors. The appearance of the tumor. Peritumoral edema. Mass effects and displacements. Hydrocephalus. The comparative sensitivity of different pulse sequences. Differentiation of tumor types. Differential diagnosis between tumors and other conditions. Effects of treatment. Comparison with X‐ray CT. Discussion. The physical basis for increased relaxation times. Volume scanning. Multislice imaging. Paramagnetic contrast agents. Tissue characterization. Particular aspects of childhood tumors. Epilepsy. Response to therapy and detection of recurrence. Summary.
Magnet field profiling: Analysis and correcting coil design
Authors: Roméo Françoise , Hoult D. I. 
Published: March 2007

AbstractA full mathematical framework for the analysis and production of localized magnetic field profiles is presented. Of primary use in the production of highly homogeneous fields for nuclear magnetic resonance studies, the paper details the analysis of fields in terms of spherical harmonics, describes how field plotting in the appropriate manner may be used to obtain a direct measure of which harmonics are present, and shows how to combine basic “building blocks” to produce the various lower‐order zonal and tesseral harmonics. “Building blocks” described include coils, arcs, and sinusoids of current as well as rings and arcs of steel. The use of shaped magnets is also briefly mentioned. Attention is drawn to the presence, in high‐order designs, of possibly dominant lower orders of harmonics created by errors in fabrication. The goal of the paper is to present a design philosophy, backed by the appropriate mathematics, which is applicable to the variety of situations encountered in magnet design. Practical examples of correcting coils and “shims” are also given.
metabolic recovery after exercise and the assessment of mitochondrial function in Vivo in human skeletal muscle by means of 31P NMR
Authors: Arnold D. L. , Matthews P. M. , Radda G. K. 
Published: March 2007

AbstractIt has been suggested that the rate of phosphocreatine resynthesis after exercise is an index of mitochondrial oxidative metabolism in intact muscle. To investigate this hypothesis, the time courses of metabolite recovery following mild and more severe dynamic exercise of human forearm muscle were compared by means of 31P NMR. Severe exercise resulted in greater net hydrolysis of phosphocreatine and greater intracellular acidosis than light exercise. The rate of phosphocreatine resynthesis was significantly slower during recovery from the more severe exercise. To explain this it was noted that, as a consequence of the high activity of creatine kinase in the sarcoplasm, the [phosphocreatine] at any time is a function of the intracellular pH. Calculations demonstrate that the difference between rates of phosphocreatine recovery after the two exercise protocols was primarily determined by the rates of recovery of the intracellular pH to normal rest values. It is concluded that the calculated rate of recovery of the cytosolic free [ADP] to its pre‐exercise concentration may provide a more specific measure of mitochondrial oxidative activity.
Measurement of Spin‐Lattice Relaxation Times in Double Spin‐Echo Imaging
Authors: Lin Max S. 
Published: March 2007

AbstractCalculation of tissue T1 in double spin‐echo imaging (90°–T‐180°–2T‐180°) using two repetition times (b1 and b2) has entailed an approximation that ignores the two 180° pulses. The theoretical consequence of the simplification is to overestimate T1 with a fractional error that increases with increasing T1 faster than linearly in a manner dependent on the sequence parameters. With b1, b2, and T as parameters, the theory gives a family of curves relating T1 to the predicted ratio of signals acquired at b2 versus b1 intervals. Tissue T1 can be determined from the observed signal ratio with no approximation. Consideration of noise effect on the precision of T1 so determined favors the use, within limits, of higher b2/b1 ratio for the same b1 + b2 time. At constant b2/b1, using longer b1 + b2 permits wider range of T1 to be measurable with a specified minimum precision.
Determinants of Proton Relaxation Rates in Tissue
Authors: Koenig Seymour H. , Brown Rodney D. 
Published: March 2007

AbstractIt is well established that the longitudinal magnetic relaxation rate of solvent water protons, 1/T1, increases markedly in homogeneous protein solutions as the magnetic field is reduced well below the traditional NMR range. For a 5% solution of protein of 105 Da, for example, 1/T1 increases from about 50% above the pure water rate of 20 MHz to five times the water rate at 0.01 MHz. For tissue, including blood, the behavior is similar. Data for blood show that extracellular water has ready access to the hemoglobin inside red blood cells, which causes the enhanced relaxation. The extent to which cell water can sample the spatial structure of soft tissue, and how this structure influences relaxation rates, is as yet unknown. Nonetheless, the relaxation data for tissue can be accommodated within the conceptual framework developed earlier for analyzing homogeneous solutions of diamagnetic proteins. The variation of 1/T1 with field differs among tissues, and its magnitude at a given field can vary by more than a factor of three, far more than does the water content of the tissues. Solute complexes of paramagnetic ions with macromolecules, which increase the relaxation rates of solvent protons, can be introduced intravenously in tissue. They are known to accumulate in specific organs, and therefore have potential utility as contrast‐enhancing agents in NMR imaging. Mn2+ and Gd3+, for example, produce characteristic dependences of 1/T1 on magnetic field that vary with the chemical state of the agent. The possibility exists, therefore, for monitoring the in vivo biochemistry of these agents.
Magnetic field dependence of proton relaxation rates in tissue with added Mn2+: Rabbit liver and kidney
Authors: Koening Seymour H. , Brown Rodney D. , Goldstein Edward J. , Burnett Keith R. , Wolf Gerald L. 
Published: March 2007

AbstractSince contrast in magnetic resonance imaging (MRI) is so sensitive to the magnetic relaxation rates of tissue protons, the use of paramagnetic ions to alter contrast in a tissue‐specific fashion is an alluring prospect. The influence of these ions on the proton relaxation rates in homogeneous solutions is known to vary dramatically according to whether the ions are present as hydrated aquoions, in solute chelate, or immobilized in macromolecules. In tissue, there is the additional complication of access of water to the ions. In the present study, Mn2+ ions were introduced into rabbits both orally and intravenously in various chemical complexes. Accumulation of these ions in rabbit liver is demonstrated here, qualitatively, by MRI. The quantitation of the change in relaxation rates is investigated in excised samples of liver and kidney by study of the magnetic field dependence (dispersion) of the relaxation rates of the protons (NMRD profiles) of tissue water. Results are presented for several sets of experiments, including doseresponse data for weakly chelated Mn2+ and time‐response data for free and complexed Mn2+. The general findings are that, for liver, the response (the increment in the NMRD profile) is relatively rapid (<2 m); that it is relatively independent of how, or in what form, the Mn2+ is introduced; that it persists for several hours (at least); and that it saturates with increasing body load of Mn2+. Moreover, from the form of the NMRD profiles of liver, it is clear that the Mn2+ ions are bound irrotationally, perhaps to cell membrane, and, when introduced in chelated form, can become separated even from strongly associated chelate complexes. For kidney, the results are qualitatively similar, though different in detail.
The use of agar gel as a basic reference material for calibrating relaxation times and imaging parameters
Authors: Vre R.Mathur‐De , Grimee R. , Parmentier F. , Binet J. 
Published: March 2007

AbstractThe relaxation properties of agar gels render it a potentially useful basic reference material for calibrating the NMR equipment. The T1 and T2 values are close to the values observed for most biological tissues; they are stable and can be varied by controlling the concentration of MnCl2. The temperature, concentration, and volume dependence of T1 and T2 were studied.
Sensitive‐volume localization for in vivo NMR using heteronuclear spin‐echo pulse sequences
Authors: Robin Bendall M. , Pegg David T. 
Published: March 2007

AbstractHeteronuclear spin‐echo techniques, which require the application of an inversion pulse on the second heteronucleus, may be applied with inhomogeneous rf coils such as surface coils. There are important applications in vivo including the detection of 13C‐ labeled and 15N‐labeled metabolites in the 1H NMR spectrum. Using a depth pulse scheme for the 1H spin‐echo sequence, and particular single or composite 13C pulses, two sensitive volumes are generated by the 1H and the 13C rf coils and signal is only obtained from the region of overlap between the two sensitive volumes. This method of signal localization for in vivo applications can be extended to 1H homonuclear editing and selective polarization‐transfer techniques. The off‐resonance characteristics of several different composite pulses are explored.
Performance evaluation of whole‐body NMR scanner antenna systems
Authors: Sergiadis George 
Published: March 2007

AbstractWhole‐body NMR imaging antennas (probes) are strongly affected by the inevitable magnetic and controllable dielectric losses. Using a convenient parallelepiped model, the magnetic losses are evaluated. By introducing the “ideal power gain,” the best possible antenna performance is delimited as a function of the frequency and the patient examined. By using a cylindrical model and introducing the “electrostatic quality factor” (EQF), the dielectric loss of any antenna can be estimated. With the help of the wideband field measurer described, a simple experimental arrangement, and the analysis developed, the performance of whole‐body NMR antennas can be compared and/or evaluated. An example is given for the application of this model at 6.4, 21, and 64 MHz for three typical patients.
Identification and characterization of tissues by T2‐selective whole‐body proton NMR imaging
Authors: Gersonde K. , Tolxdorff T. , Felsberg L. 
Published: March 2007

AbstractT2‐selective proton imaging at 10 MHz is based on a Carr‐Purcell‐Meiboom‐Gill pulse sequence with at least 36 echoes and 2τ ≃ 6 ms employing the projection reconstruction technique. The transverse magnetization decay of the volume elements is multiexponential composed of up to three monoexponential T2 components. The T2 values are arranged in T2 histograms which are slice specific. T2 windows are defined in the T2 histogram and used for imaging and for selecting T2 values which are assigned to proton classes and tissues. Tissue characterization is based on the visualization of differences in T2 behavior. The T2 values are transformed into 256 gray levels or, by use of a red‐green‐blue lookup table, into a rainbow code. Two display techniques have been developed and implemented in the RWTH Aachen Magnetic Resonance Software System (RAMSES): (i) for nonselective T2 imaging with secondary T2 selection and encoding of molecular classes on the basis of T2 values; (ii) for T2‐selective imaging by employing combined primary and secondary T2 selection and encoding particular tissues and variations therein. The tissues can be identified by selecting different classes of molecules, like water, lipids, and proteins, when shifting the primary T2 window on the T2 axis of the T2 histogram.
A Magnetic Shield for Large‐Bore, High Field Magnets
Authors: Ewing James R. , Timms Williams , Williams J. E. C. , Welch K. M. A. 
Published: March 2007

AbstractAn effective shield for the de fringing field produced by a large‐bore, high field magnet intended for imaging and in vivo spectroscopy is presented. While limiting the extent of fringe fields, the shield has little effect on the homogeneity of the central field of the magnet. The effect of institutional safety policies as well as the exigencies of patient access in a hospital environment are emphasized as influences on the planning of an in vivo NMR installation.© 1985 Academic Press,Inc.
Nuclear Magnetic Resonance Probes for Investigations of the Virus‐Cell Interactions
Authors: Valensin Gianni , Valensin Pier E. 
Published: March 2007

AbstractMeasuring the NMR relaxation parameters of selectively excited protons within molecules bound to the cell membrane was shown to provide a profitable way of looking at the viruscell interaction. Such approach made it possible to delineate the virus adsorption to human red blood cells by using the NMR features of the cytoskeleton inhibitor colchicine.© 1985 Academic Press,Inc.
A Novel Double‐Surface Coil Approach to Phosphorus‐31 Spectroscopy: A Study of Hemispheric Brain Injury in the Rat
Authors: Chew Wil M. , Moseley Michael E. , Nishimura Merry C. , Hashimoto Takahiro , Pitts Larry H. , James Thomas L. 
Published: March 2007

AbstractAn arrangement of two surface coils was devised to allow phosphours‐31 (31P) NMR spectroscopy of a localized hemispheric brain injury model in the rat. Two elliptical (8×12mm) surface coils are placed parallel to each other (3 mm apart) over each side of the rat head. Spectra are collected from either the normal or the injured side of the head using the appropriate surface coil. A passive detuning method was used to eliminate unwanted coil‐coil interactions. 31P imaging results with the two coils on phantoms show excellent isolation (6% signal overlap) between the two coils. The two‐coil set up was then used to follow a time course of injury from the hemispheric injury model.© 1985 Academic Press,Inc.