bluuebunny/crossref_metadata_2025_split huggingface dataset:
Water‐suppressed volume‐selected 1H NMR spectroscopy in viva: Application to study tumor metabolism
Authors: Haseler Luke J. , Galloway Graham J. , Field James , Irving Michael G. , Doddrell David M. 
Published: March 2007

AbstractVolume selection using SPACE has been combined with water suppression techniques to provide high‐resolution 1H NMR spectra from aqueous solutions. The technique developed was used to obtain spectra from a tumor growing on the hind leg of a rat. Water suppression factors of between 1000 and 2000 were achieved simultaneously with excellent volume selection.
Mobile phospholipid signals in NMR spectra of cultured human adenocarcinoma cells
Authors: Guidoni L. , Mariutti G. , Rampelli G. M. , Rosi A. , Viti V. 
Published: March 2007

AbstractAn intense peak is visible in the phosphodiester region of the 31P NMR spectra of human colon adenocarcinoma HCT‐8R cells. A signal at the same frequency, partially deriving from mobile phospholipids, is also observable in the spectra of total membranes and of perchloric acid extracts prepared from the same cells. The phosphodiester signals of glycerophosphorylcholine, glycerophosphorylethanolamine, and glycerophosphorylserine resonate at lower fields with respect to this broader peak and appear only in aged samples. Enzymatic treatments of the extracts would indicate that ribonucleic acid also contributes to the broad phosphodiester signal. Moreover, 1H NMR spectra show the presence of lipid structures, characterized by high mobility, in the cell and in the membrane samples, similar to what was already observed in other tumor cells and tissues. © Academic Press, Inc.
Acquisition order and motional artifact reduction in spin warp images
Authors: Dixon W. Thomas , Brummer Marijn E. , Malko John A. 
Published: March 2007

AbstractMultiple averaging can be a powerful tool against motional artifacts if significant motion occurs between the redundant acquisitions taken at a given gradient strength. However, if the time delay between these redundant measurements is too short, data or images depicting the patient is exactly the same position will be combined. Pooling such identical data has no effect on motional artifacts. This problem can be solved by increasing TR, increasing the number of redundant acquisitions, or changing the order in which acquisitions are taken. Usually all acquisitions at a particular value of the warp gradient are taken before proceeding to the next gradient value. This order minimizes motion between redundant acquisitions and so maximizes artifacts. The effect of other acquisition orders on both periodic and nonrepetitive motion is discussed. Human images for breathing and phantom results for Single‐Occurrence motions are presented. © 1988 Academic Press, Inc.
Accurate quantification of in vivo31P NMR signals using the variable projection method and prior knowledge
Authors: van der Veen J. W. C. , de Beer R. , Luyten P. R. , van Ormondt D. 
Published: March 2007

AbstractFree induction decay signals are analyzed by fitting a model function directly in the time domain. No starting values are needed for linear model parameters, and omission of corrupted data points poses no problems. A significant gain of accuracy is achieved by imposing prior knowledge about the model parameters. © 1988 Academic Press, Inc.
Multiline chemical‐shift (MULCH) imaging
Authors: Johnson G. , Tofts P. S. 
Published: March 2007

AbstractA fast chemical‐shift imaging technique is presented. The method involves saturating all spins outside a plane, selectively exciting individual lines, phase encoding along each line, sampling the FID without gradients, and interleaving interrogation of multiple lines. A 64 × 64 array of spectra with 5 Hz resolution can be obtained in 17 min. © 1988 Academic Press, Inc.
Non‐Brownian water self‐diffusion in lung tissue
Authors: Kveder M. , Lahajnar G. , Blinc R. , Zupančič I. 
Published: March 2007

AbstractPulsed field gradient NMR measurements of rat lung tissue have shown that the apparent water self‐diffusion coefficient is nearly an order of magnitude smaller than that of free water and moreover is not constant but vanes as the inverse square root of the diffusion time. The mean square displacement of water molecules is similarly proportional to the square root of the diffusion time. Possible origins of this non‐Brownian behavior are discussed. © 1988 Academic Press, Inc.
Determinants of water proton T1 in blood serum
Authors: Raeymaekers H. H. , Borghys D. , Eisendrath H. 
Published: March 2007

AbstractWater proton T1 (10.7 MHz; 7°C) and albumin and globulin contents were measured in the blood serum of 30 normal volunteers. The T1 relaxivity of serum albumin and globulin (i.e., the change of water relaxation rate l/T1 per concentration unit) was determined in pure albumin and globulin solutions. It is shown that more than 90% of the serum relaxation rate 1/Tl is due to the proteins, making T1 a nonspecific blood parameter. In addition five pathological serum samples were examined, explaining clearly why serum T1is not a clinically useful measurement. © 1988 Academic Press, Inc.
Sodium NMR imaging of lung water in rats
Authors: Kundel Harold L. , Shetty Anil , Joseph Peter M. , Summers Ronald M. , Kassab Eleanor A. , Moore Bethanne 
Published: March 2007

AbstractCoronal proton and sodium images of control rats and rats with either increased permeability edema produced by intravenous alloxan (300 mg/kg) or increased pressure edema produced by saline infusion (2 ml/min) were obtained. Axial chest CT images were used to monitor the development of pulmonary edema. Immediately after the imaging session compartmental lung water was measured gravimetrically. The sodium and proton imaging were done sequentially in a 31‐cm‐bore 1.9‐T magnet without moving the animal. The anatomical boundaries of the lung on the proton images were transferred to the sodium images for calculation of the average sodium signal intensity which was determined by extrapolating the mean values from five echoes to time zero. The sodium signal intensity was correlated (r = 0.7) with the total water fraction. There was poor correlation (r = 0.56) with the extravascular water due to confounding by the sodium vascular signal. © 1988 Academic Press, Inc.
Effect of phase‐encoding direction upon magnetic resonance image quality of the heart
Authors: Thickman David , Rubinstein Ronald , Askenase Alan , Cabellero‐Saez Annette 
Published: March 2007

AbstractIn order to optimize overall cardiac image quality on MR images experienced observers were asked to rank and rate MR images of the heart. The effect of phase‐encoding direction and use of cardiac triggering with and without respiratory gating was examined in three orthogonal imaging planes. Results indicate that use of both respiratory and cardiac gating yields the best images. Adequate images of the heart can be obtained without respiratory gating. The quality of images of the heart can be optimized by proper selection of the direction of the phase‐encoding gradient. These are improved by using horizontal phase encoding in the sagittal plane and vertical phase encoding in transverse and coronal planes. © 1988 Academic Press, Inc.
Magnetic field shimming by fourier analysis
Authors: Brateman Libby , Bowman Thomas T. , Dønstrup Sune , Scott Katherine N. 
Published: March 2007

AbstractThe homogeneity of the magnetic field of an Oxford 85/310HR magnet was optimized with the use of passive shims (i.e., pieces of steel) and room‐temperature electronic shims. Both the characteristics of the passive shims and the current settings for the room‐temperature electronic shims were calculated with the goal of minimizing field inhomogeneities as assessed by Fourier analysis of data from circular field plots. The measurement techniques, the methods of data analysis, and the techniques employed in correcting the magnetic field are presented. Difficulties and constructive approaches are suggested in these descriptions. The final results show a field of excellent homogeneity over a 10‐cm‐diameter spherical volume, with a peak‐to‐peak variation of 3.2 ppm, which is better than the manufacturer's expected specification of 5 ppm. A water‐filled sphere of 10 cm diameter gave a half‐height linewidth of 0.14 ppm after a small amount of additional touch‐up shimming. The field homogeneity as corrected is much improved over its original state, allowing the acquisition of improved spectra from samples of a size several centimeters in each linear dimension. Thus the field homogeneity is more useful for in vivo spectroscopy, the purpose for which the magnet was intended. © 1988 Academic Press, Inc.
In vivo magnetic resonance imaging of sodium in the human body
Authors: Ra J. B. , Hilal S. K. , Oh C. H. , Mun I. K. 
Published: March 2007

AbstractSodium magnetic resonance imaging of the human body in vivo has been tried and its clinical application is considered. A short T2 imaging algorithm with total volume excitation and a specialized RF coil focused to the region of interest have been adopted to improve the signal‐to‐noise ratio. Using a 1.5‐T human body imaging system, several important organs including heart, liver, gallbladder, kidney, and spine have been examined to demonstrate their sodium concentration in vivo. © 1988 Academic Press, Inc.
Very rapid lactate measurement in ischemic perfused hearts using 1H MRS continuous negative echo acquisition during steady‐state frequency selective excitation
Authors: Keller Andrew M. , Sorce Dennis J. , Sciacca Robert R. , Barr Mark L. , Cannon Paul J. 
Published: March 2007

AbstractUsing 1H MRS continuous negative echo acquisition during steady‐state frequency selective excitation (CASTLE) myocardial lactate accumulation was followed in a globally ischemic perfused rat heart model. 1H MRS CASTLE derived lactate determinations were verified biochemically and were measured during ischemia and reperfusion (both in the absence and in the presence of a known inhibitor of glycolysis). In addition, using the Bloch equations modified for the effect of diffusion in the presence of a magnetic field gradient the theoretical dependency of measurements made with CASTLE upon T1 T2 and the flip angle α were demonstrated. It was found that 1H MRS CASTLE allowed for rapid identification of the lactate ‐CH3 resonance in an isolated perfused heart with little shimming required, and excellent water and lipid suppression. Measurements of lactate using this technique reflected a true difference in myocardial lactate as evidenced by biochemical analysis and the expected changes in tissue lactate that accompanied reperfusion and ischemia in the presence of a glycolytic inhibitor. Theoretical calculations demonstrated that the dependency of the relative signal intensity obtained with 1H MRS CASTLE was a complex function of T1 T2, and α These calculations also demonstrated the theoretical feasibility of applying 1H MRS CASTLE to localized spectroscopy using a surface coil. © 1988 Academic Press, Inc.
The application of depth‐pulse localized 31P NMR spectroscopy to monitor tumor metabolism and response to chemotherapy in the rat kidney
Authors: Stewart C. A. , Hanstock C. C. , Allen P. S. 
Published: March 2007

AbstractTo illustrate the spatial variations in metabolism within tumors, 31P spectral data are presented from a predefined, depth‐pulse localized region of a rat kidney impregnated with Walker sarcoma cells. These data display the changes in energy metabolism during infiltration of the kidney by the tumor and during treatment of the tumor with cyclophosphamide. © 1988 Academic Press, Inc.
31P NMR relaxation time studies of 2,3‐diphosphoglycerate in solution and intact erythrocytes
Authors: Christensen Marianne , Jacobsen Jens Peter 
Published: March 2007

AbstractThe 31P T1 spin‐lattice relaxation times and nuclear Overhauser effects of 3‐P and 2‐P in 2,3‐diphosphoglycerate (2,3‐DPG) have been measured in pure water solutions and in suspensions of intact erythrocytes. It was found that extremely careful purification of the water solutions from paramagnetic impurities was necessary in order to obtain reproducible results. The dominant relaxation mechanism in purified samples was shown to be the dipole‐dipole interaction. Contributions from the chemical‐shift anisotropy mechanism were demonstrated to be important at higher magnetic field strengths. Based upon the measurements in water solutions and intact erythrocyte suspensions it was concluded that there could be observed no significant influence of the oxygenation state of hemoglobin on the 31P T1 values of 2,3‐DPG. © 1988 Academic Press, Inc.
NMR measurement of the degree of oil/water partition of paramagnetic contrast media
Authors: Hall Laurance D. , Hogan Patrick G. 
Published: March 2007

AbstractMagnetic resonance imaging techniques have been used to evaluate the oil/water partition of a series of stable nitroxide free radicals. The degree of partition, K, closely parallels the order of chemical polarity and lipophilicity of these compounds. This method also provides insight into both their nuclear magnetic resonance relaxation characteristics and pharmacokinetics. © 1988 Academic Press, Inc.
Paramagnetic contrast enhancement at 0.02 T: An experimental study using Gd‐DOTA in normal and hydronephrotic kidneys
Authors: Niemi Pekka , Paajanen Hannu , Määttänen Heli , Komu Markku , Erkintalo Minna , Alanen Anu , Dean Peter B. , Kormano Martti 
Published: March 2007

AbstractBoth normal and experimentally hydronephrotic rabbits were imaged at 0.02 T using partial saturation (PS 160/30) and inversion recovery (IR 1000/200/40) sequences. The signal intensity of normal renal medulla and cortex markedly increased after the injection of 0.1 mmol/kg of Gd‐DOTA. In the unilateral total hydronephrosis the dilated renal pelvis did not contrast enhance after 15 and 35 min of Gd‐DOTA injection. The enhancement pattern was similar in 1‐ and 3‐week‐old hydronephrosis. The effect of Gd‐DOTA on renal T1 times at 0.02 T was studied using rats. Fifteen minutes after the Gd‐DOTA injection (0.1 mmol/kg) the TI times of excised rat kidneys decreased from 311 to 90 ms. The authors conclude that the enhancement of the MR signal of the kidney by Gd‐DOTA at an ultralow magnetic field (0.02 T) is similar to its enhancement at higher fieldss (>0.15 T). © 1988 Academic Press, Inc.
31P FLASH NMR Imaging
Authors: Haase A. , Leibfritz D. , Werk W. 
Published: March 2007

AbstractA method of 31P FLASH NMR imaging is described using a low flip angle excitation pulse and three‐dimensional Fourier transform spectroscopic imaging (3DlT). In vivo high‐resolution 31P NMR spectra are obtained for each of 32 × 32 image elements using a minimum measuring time of 1.5 min. 31P FLASH images of a rat showing the spatial distribution of phosphocreatine, α‐, β‐, and γ‐ATP have been measured in a 4.7‐T magnet with a spatial resolution of 6 mm. © 1988 Academic Press, Inc.
Differentiation of human tumors from nonmalignant tissue by natural‐abundance 13C NMR spectroscopy
Authors: Halliday Karen R. , Fenoglio‐Preiser Cecllla , Sillerud Laurel O. 
Published: March 2007

AbstractHigh‐quality, high‐resolution, proton‐decoupled natural‐abundance 13C NMR spectra have been obtained in vitro at 100.6 MHz from unprocessed human pathology specimens of tumors and adjacent nonneoplastic control tissues from lung, colon, and prostate. In these preliminary studies, specific molecular parameters were identified from the spectra that distinguished neoplastic from nonneoplastic tissue of a given organ in all sites studied. The NMR results were congruent with data derived from histochemical and biochemical examinations of the tissues and with previous studies using non‐NMR methods. In particular, a comparison of the spectra of prostatic adenocarcinoma with that of adjacent hyperplastic tissue revealed the following differences: The tumors contained (1) larger amounts of triacylglycerols, (2) smaller amounts of citrate, and (3) acidic mucins. These transformation‐associated deviations from the normally high amounts of citrate and low amounts of lipids in the prostate are consistent with an alteration in either the concentration or the activity of ATP‐citrate lyase in the tumors. The 13C NMR spectra of colonic adenocarcinoma tissue showed that this tumor type contained (1) smaller signals from triacylglycerols, (2) larger signals from phospholipids and lactate, and (3) decreased lipid fatty acyl chain saturation, when compared to spectra from adjacent normal colon. Colloid carcinoma, another variant of colonic carcinoma, showed prominent 13C resonances from glycoproteins, which were absent from the spectra of normal colon, and from spectra from the more common pattern of colonic adenocarcinoma. Smaller 13C NMR signals from mucins and other proteins, and the presence of triacylglycerol signals distinguished poorly differentiated lung carcinoma and from nonmalignant lung tissue. These results indicate that natural‐abundance 13C NMR spectroscopy may constitute a unique, nondestructive method, for the simultaneous measurement of a large number of tissue metabolites and structural components of significance to the study and diagnosis of a wide range of human tumors. © 1988 Academic Press, Inc.
Analysis by the Carr–Purcell–Meiboom–Gill sequence of the influence of P388 leukemia and of cis‐diamminedichloroplatinum(II) nephrotoxicity on water compartmentalization in kidneys and spleens of mice
Authors: François A. , Van Gerven L. , Atassi G. , Eisendrath H. , Gielen M. , Willem R. 
Published: March 2007

AbstractThe multiexponential behavior of the decay curves obtained in vitro by a Carr‐Purcell‐Meiboom‐Gill (CPMG) sequence from spleens and kidneys of mice is analyzed. The mice were inoculated with the acute lymphocytic P388 leukemic cells and treated with the anticancer drug cis‐diamminedichloroplatinum(II), cis‐Pt. Kidneys and spleens of control animals display four relaxation components. The two longest ones were assigned, in the kidneys, in decreasing order of their relaxation time value, to intracellular and extracellular water, respectively. In spleens, the reversed assignment resulted. The two shortest ones are assigned to different tightly bound hydration water compartments, the fastest relaxing one being more greatly influenced by the unobservable crystalline water. No significant systemic effect on the intra‐ and extracellular water relaxation times could be observed in the kidneys under P388 leukemia inoculation, despite an apparent increase in the intracellular water content. In contrast, drug administration results in the apparent decrease in or even disappearance of the extracellular water component, with an increase in both relaxation time and apparent fraction of the intracellular water. These effects correlate well with changes in the usual nephrotoxicity parameters and are explained in terms of the well‐known cell damage in kidneys under cis‐platinum administration. A systemic effect under P388 leukemia disease is observed for the spleen, resulting again in the disappearance of the extracellular water component. The latter is related to splenomegaly due to invasion of the organ by leukemic cells during disease development. © 1988 Academic Press, Inc.
Relaxometry of calf lens homogenates, including cross‐relaxation by crystallin NH groups
Authors: Beaulieu Christopher F. , Clark John I. , Brown Rodney D. , Spiller Marga , Koenig Seymour H. 
Published: March 2007

AbstractWe studied the magnetic field dependence of the longitudinal relaxation rates of water protons (1/T1 nuclear magnetic relaxation dispersion (NMRD) profiles) in transparent homogenates of calf lens. The samples included nuclear homogenates with total (heterogeneous) crystallin contents between 34% (v/v) (native) and 14% (diluted) as well as cortical homogenate, 21% (native) and 34% (concentrated). The NMRD profiles had two components: a monotonic dispersive component (analogous to that of both globular protein solutions and diamagnetic tissue) and “14N quadrupolar peaks.” 14N peaks have never been reported for protein solutions, only for tissues and dehydrated proteins. These peaks occur between 0.5 and 5 MHz proton Larmor frequency and arise from interactions of solvent water protons with NH moieties of proteins. The 14N peaks in lens cytoplasm are very large and may correlate with the crystallin structure and interactions required to maintain short‐range order and lens transparency. The monotonic and 14N quadrupolar components were largest in concentrated samples, but with different concentration dependencies. The dispersive components of samples above ≈ 19% protein concentration had a fixed functional form, the amplitude of which vaned with protein volume fraction, f, by the multiplicative factor f/(1 ‐ f), suggesting spatial organization and dynamics of the solute proteins that are relatively independent of water content. In contrast, at concentrations less than 19%, the NMRD profiles are concentration dependent, indicating a dependence of the orientational relaxation time of the proteins on protein‐protein interactions seen previously in other globular proteins at these concentrations. The 14N peaks are not resolved below ≈ 19% protein and increase linearly with incremental volume fraction at protein concentrations above 19%. In addition, the 14N peaks in nuclear homogenates are 50–100% larger than those ofcortical homogenates at the same concentrations. Partial substitution of solvent D2O for H2O decreases the peak heights, indicating that an exchangeable proton mediates the interaction between solvent protons and protein 14N nuclei. © 1988 Academic Press, Inc.
Number of inner‐sphere water molecules in Gd3+ and Eu3+ complexes of DTPA‐amide and ‐ester conjugates
Authors: Geraldes Carlos F. G. C. , Sherry A. Dean , Cacheris William P. , Kuan Kah‐Tiong , Brown Rodney D. , Koenic Seymour H. , Spillers Marga 
Published: March 2007

AbstractThe inner‐sphere water coordination number for Eu3+ and Gd3+ complexed with five DTPA analogs, in which one or two terminal carboxylate groups are functionalized as propyl amides or propyl esters, have been studied using phosphorescence lifetime and nuclear magnetic relaxation dispersion (NMRD) measurements. Both methods show that the water coordination number does not increase above that observed for the analogous DTPA complexes. The phosphorescence lifetime results indicate that all five Eu3+ complexes have one inner‐sphere water molecule at 25°C. The NMRD profiles for three of the Gd3+ complexes at 25°C are also consistent with one inner‐sphere water molecule, whereas two complexes have profiles consistent only with a mixture of complexes, 50% containing a single water molecule and 50% with none. Lowering the temperature alters the population of these species such that all five Gd3+ complexes have significantly less bound water on average at 5°C. These results explain the anomalous temperature dependencies of the NMRD curves reported previously for the Gd(DTPA)–protein conjugates. We suggest that the Gd(DTPA)–conjugate systems have a fluxional coordination sphere whereby the amount of inner‐sphere coordinated water vanes from near zero at 5°C to a high Of two near 37°C. © 1988 Academic Press, Inc.
In Vivo13C NMR Spectroscopy of the Human Prostate
Authors: Sillerud Laurel O. , Halliday Karen R. , Griffey Richard H. , Fenoglio‐Preiser Cecilia , Sheppardy Scott 
Published: March 2007

AbstractThe metabolism of the normal and hyperplastic human and rat prostate differs from that of other tissues in that this organ supports and secretes high concentrations of citrate. During the dedifferentiation process that is characteristic of neoplasia, the ability of the prostate to maintain these high citrate levels is markedly diminished. We undertook a natural abundance 13C NMR study of the human and rat prostate in vitro and the human organ in vivo in order to determine whether the amounts of citrate in the nonmalignant prostate were sufficiently high to be detected. We report here our success at detecting citrate via 13C NMR in all three of these systems. © 1988 Academic Press, Inc.