bluuebunny/crossref_metadata_2025_split huggingface dataset:
In vivo19F nuclear magnetic resonance spectroscopy of trifluorinated neuroleptics in the rat
Authors: Albert K. , Rembold H. , Kruppa G. , Bayer E. , Bartels M. , Schmalzing G. 
Published: March 2007

AbstractIn vivo 19F NMR measurements of trifluorinated neuroleptics in the rat brain were made using a 13 × 18 mm surface coil at 4.7 T. The signal of fluphenazine was obtained within 8–15 min from brains of living rats treated chronically with drug doses of 5–30 mg/kg. Following the intravenous injection of a single dose of trifluoperazine (30 mg/kg), brain levels could be monitored with a time resolution of 30 min. The data demonstrate the possibility of obtaining in vivo pharmacokinetics of fluorinated agents in the rat brain. 19F NMR is expected to become an important tool in neurochemical research.
Spatially‐localized NMR spectroscopy employing an inhomogeneous surface‐spoiling magnetic field gradient 1. Phase coherence spoiling theory and gradient coil design
Authors: Chen Wei , Ackerman Joseph J. H. 
Published: March 2007

AbstractThe use of a current‐generated, inhomogeneous, surface‐spoiling magnetic field gradient for enhancing magnetic resonance spatial localization, by rapidly inducing spin phase incoherence in surface lying regions of a sample is examined theoretically. A geometrically simple surface‐spoiling magnetic field gradient coil design is presented and its gradient field characterized via computer simulations. Mathematical expressions describing the time dependence of net sample spin phase coherence under influence of the spoiling gradient are developed for application with homogeneous (B1) volume coils. The dependence of spoiling efficiency on the magnetogyric ratio of the nuclide under investigation and on the current driving the gradient field is described. Spoiling periods of ca 1–2 ms with driving currents of ca 0.5–1.0 A are predicted to be adequate for surface‐spoiling experiments with rat, e.g., for noninvasive monitoring of liver. A companion article W. Chen and J. J. H. Ackerman, NMR Biomed., 3, 158–165 (1990)) describes implementation of the surface‐spoiling technique with multicompartment models (phantoms) and with rat in vivo.
Spatially‐localized NMR spectroscopy employing an inhomogeneous surface‐spoiling magnetic field gradient 2. Surface coil experiments with multicompartment phantom and rat in vivo
Authors: Chen Wei , Ackerman Joseph J. H. 
Published: March 2007

AbstractThe use of inhomogeneous surface‐spoiling magnetic field gradients for elimination of signal from surface lying regions of a sample was theoretically examined in the companion article (W. Chen and J. J. H. Ackerman, NMR Biomed. 3, 147–157 (1990)). Using the spoiling gradient coil design described therein, this article presents experimental verification of the feasibility of such an approach to enhanced spatial localization. Single coil mode 31P NMR surface coil interrogation of both a two compartment phantom and rat in vivo are shown to provide excellent suppression of surface lying regions with minimal degradation of signal from the deep lying region of interest. Both pulse‐and‐collect and spin echo sequences were highly efficient in concert with spoiling gradient periods of 0.5–2 ms and driving currents of 0.5–2 A. The use of a current‐generated surface spoiling gradient offers a robust means to remove surface tissue signal contributions and can be implemented with a wide range of localizing pulse sequences and imaging protocols.
Proton and phosphorus magnetic resonance spectroscopy of human astrocytomas in vivo. Preliminary observations on tumor grading
Authors: Arnold D. L. , Shoubridge E. A. , Villemure J.‐G. , Feindel W. 
Published: March 2007

AbstractWe have obtained localized, water‐suppressed proton magnetic resonance spectra from eleven astrocytomas in vivo. Localized phosphorus spectra were also obtained from three of these tumors. All tumors were examined prior to surgery, radiotherapy or chemotherapy. Examinations were performed with a commercially available 1.5 Tesla combined imaging and spectroscopy system using a stimulated echo pulse sequence for protons and an ISIS pulse sequence for phosphorus. A relatively high lactate resonance intensity correlated with a more malignant histological tumor grade and more aggressive behaviour. The resonance intensity of N‐acetylaspartate/creatine was decreased and choline/creatine was increased, but these did not reliably discriminate between tumor grades. Other unidentified resonances not present in spectra of normal brain were sometimes seen. Proton magnetic resonance spectroscopy provides a new method for determining the metabolic behaviour of astrocytomas that may be useful in the clinical assessment of patients with these tumors.
31P chemical shift imaging of the regionally ischemic perfused heart
Authors: Chatham John C. , Blackband Stephen J. 
Published: March 2007

AbstractThe application of one‐dimensional 31P chemical shift imaging to the study of the isolated perfused rat heart is described. Its applicability for the examination of regional ischemia in the isolated perfused rat heart is demonstrated. The data sets show clearly the localization to the ischemic and nonischemic regions of the heart. Such studies will permit the correlation of cardiac metabolism and function in a controlled manner that is not possible in the application of these techniques to the intact animal. In particular, the time resolution of the experiments will enable spatially localized metabolic studies to be performed during the onset of ischemia and during reperfusion.
A system for viably maintaining a stirred suspension of multicellular spheroids during NMR spectroscopy
Authors: Freyer James P. , Fink Nancy H. , Schor Patricia L. , Coulter James R. , Neeman Michal , Sillerud Laurel O. 
Published: March 2007

AbstractWe have developed a system for the perfusion of a stirred suspension of multicellular spheroids during nuclear magnetic resonance spectroscopy. Measurement of the medium temperature, pH, oxygen tension, and glucose and lactate concentrations demonstrated that the macroenvironmental conditions around the spheroids during perfusion matched those in standard spinner culture flasks. Spheroids cultured in the NMR perfusion chamber for up to 48 h were virtually identical to spheroids cultured under standard conditions in terms of volume and cell number growth, the extent of central necrosis, cellular clonogenicity, and proliferative status. To avoid problems in interpreting the NMR spectra, we have used a medium containing 10% of the normal inorganic phosphate concentration; comparative growth and NMR studies showed that this medium had no effect on the results reported. 31P NMR spectroscopic analysis demonstrated that the mean pH, nucleotide triphosphate (NTP) to inorganic phosphate (Pi) ratio, the total amount of NTP, and the total energy charge were essentially constant over 8 h of analysis. Stopping the stirring of the spheroid culture during analysis resulted in depletion of the nucleotide phosphate pool in 30 min, with an accumulation of Pi and a shift to a more acid intracellular pH. This effect could be reversed if stirring was resumed within 30 min. Stopping the perfusion while maintaining stirring resulted in a deterioration of the 31P spectra until no high energy phosphates remained at 120 min and the pH fell to ≈6. This effect was also partially reversible after 30 min of reperfusion, with recovery to a normal 31P spectrum requiring 10 h. The combination of the spheroid model system with 31P NMR spectroscopic analysis will provide a powerful tool for investigating basic questions about the regulation of tumor cell energy metabolism and viability.
Stoichiometry of phosphocreatine and inorganic phosphate changes in rat skeletal muscle
Authors: Meyer Ronald A. , Adams Gregory R. 
Published: March 2007

AbstractThe apparent T1's of phosphate metabolites were measured during and after series of twitch contractions in gastrocnemius muscles of pentobarbital‐anesthetized rats by steady‐state progressive saturation using spatially‐selective composite pulses. There was no significant change in apparent T1's of inorganic phosphate (Pi), phosphocreatine (PCr), or the three phosphates of ATP. There was a 5‐10% decrease in the sum of Pi and PCr integrals, and in the sum of the γ‐ and β‐ phosphates of ATP during stimulation, but no significant change in the ratio (Pi + PCr)/(γ‐ATP + β‐ATP). The results indicate that there is no selective decrease in NMR observable Pi during or after a series of muscle contractions.
Differences in metabolite content between intact pancreases and their perchloric acid extracts. A 2D 1H/31P correlation NMR study
Authors: Askenasy Nadir , Kushnir Tammar , Navon Gil , Kaplan Ofer 
Published: March 2007

AbstractPerchloric and hydrochloric acid extracts of intact pancreases from healthy rats and from rats with experimental acute pancreatitis were analysed using 2D 1H/31P correlation NMR spectroscopy. Major differences were found in the 2D maps between the extracts and the intact tissues. In the case of the intact diseased pancreas the prominent 31P signal at the phosphodiester region has been assigned in our previous work as lecithin/taurocholate complex. However, the signal found in the same chemical shift region in extracts of diseased pancreases as well as healthy ones, is identified here as the phosphodiester residue of oligoribonucleotides. In these extracts additional 31P signals were found and assigned as phosphomonoester and phosphodiester hydrolysis products of RNA. The amounts of these compounds, as a function of the acid concentrations were determined, and conditions for their minimization were defined.
Metabolic heterogeneity in RIF‐1 tumours detected in vivo by 31P NMR spectroscopy
Authors: Bhujwalla Z. M. , Blackband S. J. , Wehrle J. P. , Grossman S. , Eller S. , Glickson J. D. 
Published: March 2007

AbstractThe spatial distribution of phosphate metabolites and pH within subcutaneously implanted RIF‐1 tumours was determined by 1‐dimensional phosphorus chemical shift imaging. 31P spectra from two to three 4 mm thick cross‐sectional slices were obtained for each tumour. Quantitative morphometry was used to estimate the amount of necrosis within those slices. A spatially heterogeneous distribution of phosphate metabolites and pH was detected in most of the tumours. Levels of necrosis ranged from 0–24% for the tumours in this study. There was no significant correlation between the extent of necrosis over this range and levels of metabolites or pH, suggesting that factors besides necrosis can contribute to spectral heterogeneity.
Metabolic heterogeneity in brain tissue during incomplete ischemia and reperfusion
Authors: Nioka Shoko , Smith D. , Chance B. , Lockard S. 
Published: March 2007

AbstractTwo metabolically distinct cell populations were detected when two peaks of inorganic phosphate (Pi), corresponding to two pHi values, were recorded by Phosphorus Magnetic Resonance Spectroscopy (31P MRS). One cell population, having intracellular pH (pHi) values less than 6.3, was thought to contain neither PCr (phosphocreatine) nor ATP and was thus considered metabolically unstable or inactive. The second cell population, having normal or near normal pHi, was considered metabolically active with adequate values of ATP and PCr. We can therefore further analyze the bioenergetics in this cell population.The results were based upon studies of 14 ischemic dogs that were anesthetized with 2% isoflurane and ventilated. The amount of Pi associated with the acidic cell population (low pHi) was used to calculate the fraction of metaboliacally inactive brain tissues. This value correlated well with the ATP depletion of the total cell population. This suggests that in the acidic cell population, PCr and ATP supplies were depleted by dephosphorylation during ischemia, leading to an accumulation of acidic Pi. In addition, ATP synthesis in this population may be inhibited by the low intracellular pH. On the other hand, the bioenergetic state of the metabolically stable cell population having a nearly neutral pHi changed markedly during ischemia. The PCr/Pi dropped to 0.8 and the phosphorylation potential (PP) dropped to 10 mM−1 from 40 mM−1. With reperfusion, two distinct patterns of responses were observed. One group showed the restoration of ATP (recovery group) whereas the second group did not (non‐recovery group). After 3 h of reperfusion, the ATP restored group showed complete recovery of PCr. The non‐recovery group showed no restoration of PCr or phosphorylation potential and no reduction in Pi.
1H NMR Spin‐echo Spectroscopy of Human Erythrocytes. Transformation of Exogenous Compounds
Authors: Skibsted Ulrik , Hansen Poul Erik 
Published: March 2007

Abstract1H NMR spin‐echo spectroscopy has been used to study the metabolism of exogeneous compounds in human erythrocytes. The non‐invasive nature of the technique and the continuous monitoring makes it ideal to investigate both the conversion of substrates and the occurrence and the nature of the products. Hydrolysis rates may be determined and the hydrolysis of alkyl, vinyl, and aryl acetates are shown to be due to A‐esterase activity. The conversion products are normally observed, but in the case of dimethyl phthalate and methyl acetate only part of the methanol is found. An interesting case is the hydrolysis of vinyl acetate and the consecutive conversion of the vinyl alcohol to acetaldehyde (hydrate). Coupling of glutathione to a variety of vinyl derivatives is also observed. Oxidation of acetaldehyde can also be followed. Styrene and 5‐chloro‐2‐methylaniline are slowly converted in what is believed to be oxidation reactions. Changes in 1H chemical shifts are observed for a number of compounds upon uptake into human erythrocytes, a shift that is suggested to be due to binding to haemoglobin.
A method for rapid evaluation of saturation factors in in vivo surface coil NMR spectroscopy using B1‐insensitive pulse cycles
Authors: Gruetter Rolf , Boesch Chris , Martin Ernst , Wüthrich Kurt 
Published: March 2007

AbstractFor a rapid determination of saturation factors in surface coil NMR spectroscopy, the recently published (90°–τ–180°–τ–90°–τ–) SUFIR sequence was modified with adiabatic pulse cycles. Signals were acquired after each of the two 90° pulses and they were stored in different memory blocks. The deleterious offset‐dependent saturation effects inherent in adiabatic 90° excitation pulses were minimized by suitable combinations of adiabatic pulses that sweep from either side of the spectrum onto resonance, and by setting the carrier frequency in the middle of the spectrum. The practical use of the proposed method is illustrated with the determination of 31P NMR saturation factors in human calf muscle.
Evaluation of 31P NMR spectroscopy as an indicator of chemically induced hepatic toxicity in the rat: Comparison with serum enzyme levels and pathology
Authors: Sandhu G. S. , Gonnella N. C. , Kapeghian J. C. , Plocinski A. F. , Plutchok J. , Schlosser M. J. 
Published: March 2007

AbstractThe progression of carbon tetrachloride‐induced liver damage, determined by 31P NMR spectroscopy, was compared with selected serum enzyme and histological changes in rats. ATP levels declined as early as 8 h post‐CCI4 administration, with partial recovery observed at 168 h. The results show that ATP reduction correlates with necrosis. In addition, early decline in ATP occurring prior to significant hepatocellular necrosis indicates abnormal energy metabolism.
Chronic cardiotoxicity of adriamycin studied in a rat model by 31P NMR
Authors: Dekker T. , van Echteld C. J. A. , Kirkels J. H. , Ruigrok T. J. C. , van Hoesel Q. G. C. M. , de Jong W. H. , Schornagel J. H. 
Published: March 2007

AbstractAdriamycin induced cardiotoxicity is, among other factors, characterized by an impairment of mitochondrial function and altered energy metabolism. The possible merits of 31P NMR in timely detection of this cardiotoxicity were studied in perfused hearts of chronically treated rats after cumulative doses of 6,8,10,12 and 13 mg adriamycin/kg body wt and compared to histological evaluation. After high cumulative doses the Phosphocreatine (PCr)/ATP ratio was significantly decreased in the hearts of treated animals, compared to the control animals (1.65±0.13 vs. 2.47±0.36 (p < 0.001) at 12 mg/kg and 1.92 ± 0.22 vs. 2.37±0.15 (p < 0.01) at 13 mg/kg adriamycin, respectively). This decrease coincides with a sudden increase in the histological score from 2.0 at 10 mg/kg to 8.0 at 12 mg/kg adriamycin on a scale of 10.0. The Pi/PCr ratio, coronary flow and rate pressure product (RPP) of the isolated hearts of treated animals were not significantly different from controls. When heart rates were increased, parallel changes in PCr/ATP ratio, Pi/PCr ratio, RPP and coronary flow were observed in both control and treated groups, except for the 12 mg/kg adriamycin group in which pacing failed to increase RPP. In addition, in this group the Pi/PCr ratio at higher heart rates was significantly increased (p < 0.001) compared to controls. At 13 mg/kg similar effects were observed but less pronounced. The decreased PCr/ATP ratio may indicate an increased ADP concentration and altered regulation of energy metabolism. Differences between control and treated groups in RPP and Pi/PCr ratio during pacing may also be related to cardiotoxicity. The results of this study show that changes in energy metabolism in the heart during chronic adriamycin treatment may well be observed by 31P NMR. Furthermore, they indicate that clinical 31P NMR may be a suitable tool for monitoring the development of adriamycin induced cardiotoxicity, thereby avoiding the disadvantages of invasive procedures.
Effect of anaerobic metabolic changes on the creatine kinase reaction in frog muscle studied by 31P saturation transfer NMR
Authors: Yoshizaki Kazuo , Nishikawa Hiroyasu , Naruse Shoji 
Published: March 2007

AbstractThe effect of anaerobic metabolic changes on the flux of the creatine kinase reaction in bullfrog skeletal muscle was evaluated by 31P saturation transfer NMR. During an anaerobic time course the reduction ratio (M+/M0) of the phosphocreatine signal and the spin‐lattice relaxation time measured in the presence of saturating irradiation at the ATP γ‐phosphate resonance were decreased; however, the intrinsic spin‐lattice relaxation time of phosphocreatine was constant (4 s). The pseudo‐first‐order rate constant for the forward reaction of creatine kinase (i.e., phosphocreatine to ATP) was increased during the time course, accompanied by a decrease in phosphocreatine concentration and an intracellular acidification. However, the flux was constant (4 mmol . kg−1 wet wt . s−1) over the anaerobic time course. The fluxes analysed in several locations along the fibers, which were simultaneously measured by means of the one‐dimensional chemical shift imaging technique, were almost the same along the entire length of the fibers. These results indicate that the creatine kinase reaction is at equilibrium along the entire length of the frog muscle fibers.
The use of In vivo proton NMR to study the effects of hyperammonemia in the rat cerebral cortex
Authors: de Graaf A. A. , Deutz N. E. P. , Bosman D. K. , Chamuleau R. A. F. M. , de Haan J. G. , Bovee W. M. M. J. 
Published: March 2007

AbstractUsing in vivo 1H NMR spectroscopy (1H MRS) and biochemical analysis, the effects of hyperammonemia on cerebral function were studied in three rat models: acute liver ischemia (LIS), administration of urease (UREASE) and administration of methionine sulfoximine (MSO). By means of localization in three dimensions signals were obtained exclusively from the cerebral cortex. Specially developed lineshape correction and fitting methods were used to quantitate the MRS signals. The following concentration changes were observed; a decrease in glutamate and (phospho) choline for all the models; an increase in glutamine in the LIS and UREASE model but a decrease in the MSO model; a marked increase in lactate in the LIS and UREASE group; a tendency to a decrease in N‐acetylaspartate in all the models. These changes agree well with the changes in the post‐mortem biochemically determined cerebral cortex glutamine and glutamate concentrations. Estimated absolute 1H MRS metabolite concentrations agree well with those obtained by other techniques; cerebral cortex glutamate, however, is underestimated by about 35% by NMR. The present data support the hypothesis that hyperammonemia is associated with a decreased availability of glutamate for neurotransmission.
31P and 3‐fluoro‐3‐deoxy‐D‐glucose 19F In vivo NMR spectroscopy of aged rat brain
Authors: Kwee Ingrid L. , Nakada Tsutomu , Suzuki Nobuyuki 
Published: March 2007

Abstract31P and 3‐fluoro‐3‐deoxy‐D‐glucose (3‐FDG) 19F nuclear magnetic resonance (NMR) spectroscopic investigations were performed on aged rat brain in vivo. Phosphodiester (PDE) was found to be significantly higher (p < 0.05) in aged brain (18 months, n = 10) than adult controls (6 months, n = 10) suggesting accelerated phospholipid catabolism in aged brain. Inorganic phosphate (P,) levels were significantly lower (p < 0.05) in aged brain (n = 5) than in normal adult controls (5 = 5). The sorbitol index, a measure of aldose reductase activities in vivo, determined by the 3‐FDG 19F NMR method, revealed that aldose reductase activities were significantly higher (p < 0.05) in aged brain.
Impairment of muscular metabolism in chronic respiratory failure. A human 31P MRS study
Authors: Payen J.‐F. , Wuyam B. , Reutenauer H. , Laurent D. , Levy P. , Le Bas J.‐F. , Benabid A. L. 
Published: March 2007

AbstractThe calf muscle metabolism of 7 patients with stable chronic respiratory failure (PaO2 below 65 Torr) was studied using 31P NMR spectroscopy. NMR spectra were acquired at rest, during the course of 360 pedal movements at 20, 35 and 50% of the maximal voluntary contraction (MVC) and during recovery. Eight normal aged‐matched subjects served as a control group. In resting muscle, no significant differences were observed between both groups as regards intracellular pH, inorganic phosphate/phosphocreatine (Pi/PCr) and β‐ATP/PCr + Pi + phosphomonoester (PME) ratios. Although effective power outputs were similar for both groups at each work level, patients exhibited a higher Pi/PCr ratio than healthy controls (3.19 ± 1.01 vs 0.49 ± 0.05 at 50% MVC; p < 0.01) and a lower pHi (6.65 ± 0.11 vs 7.06 ± 0.02 at 50% MVC; p < 0.01). Moreover, PCr resynthesis during recovery was slower in patients than in control subjects (t1/2 PCr = 1.26 ± 0.30 vs 0.47 ± 0.05 min; p = 0.01). These results suggest impairment of aerobic capacity in a non‐ventilatory working muscle, probably due to hypoxemia in patients with chronic respiratory failure.
A review of chemical issues in 1H NMR spectroscopy: N‐acetyl‐l‐aspartate, creatine and choline
Authors: Miller Bruce L. 
Published: March 2007

AbstractThe structure and function of the chemicals contributing to the three main peaks seen with 1H NMR spectroscopy, N‐acetyl‐L‐aspartate (NAA), creatine/phosphocreatine (Cr), and choline‐containing compounds (Cho) is reviewed and the changes seen with these compounds in various disease states are briefly outlined. NAA is present within neurons although its biological function is largely unknown. NAA is elevated in several degenerative neurological conditions including amyotrophic lateral sclerosis and canavan disease, and in high concentrations it may behave like a neurotoxin. The creatine peak seen with 1H NMR spectroscopy consists of creatine and phosphocreatine which serve as a reserve for high‐energy phosphates in the cytosol of muscle and neurons. They also buffer cellular ATP/ADP. The Cho peak seen with 1H NMR consists of a complex mixture of Cho‐containing compounds. Cho is a precursor for the neurotransmitter acetylcholine and for the membrane constituent phosphatidylcholine. Future studies of changes seen in the Cho peak with stroke, degenerative dementia, drug intake, and infectious and neoplastic brain masses will be of great interest.