bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ph and compartmentation of isolated perfused rat liver studied by 31p and 19f nmr
Authors: Thoma William J. , Uurbil Kǎmil 
Published: March 2007

AbstractThe phosphorus NMR spectra of isolated perfused rat liver displays a prominent inorganic phosphate peak at 2.76 ± 0.05 ppm relative to liver glycerolphosphocholine at 0.49 ppm. From titration curves of phosphorus‐containing compounds this corresponds to a pH of 7.4. The spectra also display a shoulder on the prominent inorganic phosphate peak at 2.22 ± 0.55 ppm corresponding to a pH of 7.0. Fructose is phosphorylated in the C1 position by the liver and the resulting fructose‐1‐phosphate is located in the cytosol. From the titration curves, this compound was at pH 7.0. When inorganic phosphate was added to the perfusate, 13 of 25 livers showed two inorganic phosphate peaks resolved in the difference spectra, one originating from the perfusate, the other at pH 7.0. When large (50 mM) fructose doses were administered to the liver, the prominent peak decreased allowing two peaks to be resolved. FCCP treatment of the liver caused the two peaks to coalesce with the final pH of both the fructose‐1‐phosphate and inorganic phosphate being the same. 19F NMR of difluoromethylalanine gave an intracellular pH of 7.4 for the isolated perfused liver. The data presented do not lend themselves to satisfactory interpretation, and call into question the correctness of the traditional assignment of liver inorganic phosphate being cytosolic in origin.
In vivo31P NMR spectroscopy of the rat cerebral cortex during acute hepatic encephalopathy
Authors: Deutz N. E. P. , Chamuleau R. A. F. M. , De Graaf A. A. , Bovée W. M. M. J. , De Beer R. 
Published: March 2007

AbstractDuring the development of acute hepatic encephalopathy, induced by acute liver ischemia, changes in brain 31P NMR spectra and EEG spectra were studied over 8:45 h in eight rats. At the end of this period the brain amino acid concentrations were determined. The results were compared with the same measurements in four normal and three portacaval shunted rats. Signs of acute HE, as judged by the EEG left index, started 5 h after the induction of acute liver ischemia. No accompanying significant changes in the cortical relative phosphocreatine and ATP concentration and intracellular pH were observed. The cortical relative Pi concentration had only slightly increased at t = 8 h. The concentrations of almost all measured brain amino acids, especially glutamine had increased at t = 8:45 h. At t = 8 h, rats with very severe HE had a small, but significant decrease of brain ATP concentrations. Their brain amino acid concentrations were more disturbed than in rats with less severe HE. It is concluded that a change in the cortical cerebral energy rich phosphate concentration is not an important pathophysiological mechanism during the development of acute HE. The observed changes in brain amino acids concentrations could be either part of a multifactorial pathogenesis or could be epiphenomena.
Improvement of the rotating frame experiment by detection of residual z magnetization: a 31P MRS study of metabolite levels in a meth‐a sarcoma
Authors: Karczmar G. S. , Shine N. , Lawry T. J. , Weiner M. W. , Matson G. B. 
Published: March 2007

AbstractThe radio frequency field (B1) gradient of a surface coil can be used to obtain spectra from a series of sample regions which experience different B1 field strengths. We previously reported that the sensitivity of this method, known as the surface coil rotating frame experiment (SCRFE), can be enhanced by applying a composite pulse immediately after signal acquisition to sample residual Z magnetization which is normally undetected. Initially this modified SCRFE was used to obtain spatially resolved spectra across a B1 gradient of a factor of 2.5. Here we demonstrate the extension of this method to map phosphorylated metabolites across a B1 gradient of a factor of close to 5. Computer simulations were used to evaluate the performance of the composite pulse, and to assist in analyzing the data. The method was used to obtain 31P spectra in vivo from various tissue layers within and beneath a murine Meth‐A tumor. The spectra differentiated between metabolite levels in tumor tissue and underlying skeletal muscle. Metabolic heterogeneity within the tumor itself was also evident.
A 13C NMR study on fluxes into the krebs cycle of rabbit renal proximal tubular cells
Authors: Jans Arnold W. H. , Leibfritz Dieter 
Published: March 2007

AbstractSuspensions of rabbit renal proximal tubular (PCT) cells were incubated with [2‐13C] and [3‐13C]pyruvate. The perchloric acid extracts of the cell pellets were examined by 13C NMR. All experiments showed that enriched lactate, alanine, glutamate, and glutamine were the main metabolic intermediates, and that enrichment to a minor extent was found in the glutamate residue of glutathione (GSH). From these experiments, it could be deduced that PCT cells show a highly glycolytic activity, whereas enrichment of glucose exhibits gluconeogenesis. The estimation by 13C NMR of the ratio of the flux into the Krebs cycle via pyruvate carboxylase to the flux via pyruvate dehydrogenase is discussed. From incubations with 10 mM 13C‐labelled pyruvate, we calculated from the relative enrichments of the glutamate carbon atoms that the ratio of pyruvate carboxylase to pyruvate dehydrogenase is 1.44 ± 0.04 in rabbit renal proximal tubules.
Broadband proton decoupling in human 31p NMR spectroscopy
Authors: Luyten Peter R. , Bruntink Gerard , Sloff Frenk M. , Vermeulen Jan W. A. H. , Van Der Heijden Jan I. , Den Hollander Jan A. , Heerschap Arend 
Published: March 2007

AbstractThe limited chemical shift dispersion of in vivo 31P NMR spectra obtained at the relatively low field strengths used for human applications is the cause of poor spectral resolution. This makes it difficult to obtain accurate quantitative information from overlapping resonances, and interesting resonances may be obscured. At 1.5 T unresolved 1H–31P couplings contribute significantly to the linewidth of in vivo 31P NMR resonances. Therefore, proton decoupling can improve spectral resolution substantially, resulting in better resolved resonances and more reliable quantitative information. In this work it is shown that well resolved resonances of glycerophosphocholine, glycerophosphoethanolamine and phosphoethanolamine are obtained in 1H decoupled 31P NMR spectra of human muscle, brain, and liver. In spectra of the human heart it has been possible to resolve the myocardial Pi signal from the signals of 2,3‐diphosphoglycerate from blood. With surface coils it is difficult to achieve broadband decoupling over the entire sensitive region of the coil by using conventional decoupling sequences. This problem has been overcome by applying a train of frequency modulated inversion pulses to achieve proper decoupling despite B2 inhomogeneity. Broadband 1H decoupling of 31P NMR spectra was possible without exceeding specific absorption rate guidelines.
Image localized 31P magnetic resonance spectroscopy of the human liver
Authors: Glazer Gary M. , Smith Stephen R. , Chenevert Thomas L. , Martin Peter A. , Stevens Anthony N. , Edwards Richard H. T. 
Published: March 2007

AbstractImage localized 31P magnetic resonance (MR) spectroscopy of the liver was performed in twelve normal volunteers and seven patients with hepatic tumours. The tumours which were clearly imaged by proton MR could also be distinguished from normal tissue because of spectral differences. The malignant tumours had significantly elevated phosphomonoester/inorganic phosphate and phosphomonoester/b̃‐adenosine triphosphate ratios, probably due to elevated tumour concentrations of phosphocholine and phosphoethanolamine, which are intermediates in the synthesis of membrane phospholipids. The pH values of the malignant tumours were elevated compared to normal hepatic parenchyma. Liver spectra in two patients with the commonest benign hepatic neoplasm, cavernous haemangioma, differed from both normal tissue and the malignant tumours in having a very low signal/noise ratio but apparently normal relative levels of phosphomonoester.
31P magnetic resonance spectroscopy of the normal human brain: approaches using four dimensional chemical shift imaging and phase mapping techniques
Authors: Coutts Glyn A. , Bryant David J. , Collins Alan G. , Jane Cox I. , Sargentoni Janet , Gadian David G. 
Published: March 2007

AbstractThe use of four‐dimensional chemical shift imaging to monitor phosphorus metabolites within the human brain is illustrated. Saturation effects are described, and acquisition conditions are discussed in relation to quantification and sensitivity. The effects of magnetic field variations on spectral parameters are assessed and the use of a field mapping technique is illustrated.
An NMR Assessment of the Rheological Properties of Blood and Its Constituents: A Review
Authors: Berling C. , Hall L. D. 
Published: March 2007

AbstractThis review assesses the progress of NMR in the field of hemorheology, i.e., the assessment of the mechanical and physical characteristics of flowing blood. The review deals with the intrinsic rheological properties of the red cell and its constituents (membrane, cytoplasm), which are dominant in the microcirculation, and a section concerns the investigation of the cell/cell interaction phenomenon, known to give rise to the complicated non‐Newtonian behavior of blood under most of the flow conditions encountered in the blood circulation using NMR.
Injury and Recovery of the Liver from Preservation Assessed by 31P NMR Spectroscopy: The Contrast between Preservation with Collins' Solution and Ringer's Lactate Solutiond̊
Authors: Vine William , Link John , Thoma William J. , Uǧurbil Kâmil 
Published: March 2007

AbstractThe biochemistry of hepatic injury and recovery from preservation for transplantation was studied in rat liver perfused in vitro with erythrocytes. ATP and its metabolites, inorganic phosphate (P1) and pH were quantitated as often as every 2.5 min by 31P NMR spectroscopy during preservation and recovery. Release of the hepatocellular enzymes, lactate dehydrogenase V (LDV) and aspartate aminotransferase (AST) were also measured. The duration of preservation with Collins' solution, the standard clinical preservative, affected the rate of recovery of ATP and monophosphate esters (MP), which include AMP + IMP, and the final recovery of Pi, but not of ATP. The difference between Collins' and Ringer's lactate solution, a poor preservative, became more apparent as preservation time increased. The differences included (1) pH at the end of preservative infusion; (2) pH between 0 and 2.5 min of reperfusion; (3) the MP increase (AMP + IMP) at the end of 13 h of preservation; (4) rate of recovery of ATP after preservation; (5) final ATP recovery during reperfusion; (6) LDV after 13 h of preservation. These biochemical differences between good and poor preservation form a rational basis for prediction of liver failure after transplantation and for tests of the quality of new preservatives.
Limits of tumour treatment follow up by surface coil 31P magnetic resonance spectroscopy. The case of sarcosinamide‐CNU treated ependymoblastoma
Authors: Le Moyecd̊ L. , Le Rumeur E. , Darcel F. , Chatel M. , De Certaines J. D. , Remy C. , François A. , Lotito S. , Benabib A. L. 
Published: March 2007

AbstractEpendymoblastoma tumour bearing mice were treated with sarcosinamide‐CNU and compared with untreated mice with regard to tumour growth, pathological examinations and levels of phosphorylated metabolites measured by in vivo nuclear magnetic resonance spectroscopy. The response to the drug was demonstrated by its effect on tumour growth and with pathological examinations. Spectra evolution was different from controls for only four treated tumours out of eight.
A Selective excitation/B0 gradient technique for high‐resolution 1H NMR studies of metabolites via zero‐quantum coherence and polarization transfer
Authors: Doddrell David M. , Brereton Ian M. 
Published: March 2007

AbstractA new method for selective observation of scalar coupled metabolites by either zero‐quantum coherence transfer or polarization transfer with concurrent water suppression in a single acquisition was developed. Gaussian shaped RF pulses were used to selectively generate multiple‐quantum and zero‐quantum coherence in the metabolite of interest, single quantum (including water) and double quantum coherences were then dephased under the influence of a B0 field gradient and the surviving zero‐quantum coherence was converted to observable metabolite signal. The duration of the gradient application and the frequency and angle of the final selective read pulse determined whether a polarization transfer or a coherence transfer signal was observed.Water suppression factors of around 8000 were achieved which allowed operation of the receiver at high gain levels resulting in greatly improved signal to noise in the metabolite spectra. The CH3 and CH resonances of lactate in a mouse brain homogenate were selectively edited and the method was also applied to selective editing of ethanol.
In vivo pharmacokinetics of aldose reductase inhibitors: 3‐fluoro‐3‐deoxy‐D‐glucose NMR studies in rat brains
Authors: Kwee Ingrid L. , Nakada Tsutomu 
Published: March 2007

AbstractDirect quantification of the inhibitory effects of orally administered drugs (sorbinil, cyclandelate and sulindac) on aldose reductase activities in rat brains was performed non‐invasively using the 3‐fluoro‐3‐deoxy‐D‐glucose (3‐FDG) 19F NMR spectroscopic technique. Quantitative data obtained directly from the target organ (brain) allowed for unprecedentedly accurate analysis of drug effects in the brain in vivo. Sorbinil, a potent aldose reductase inhibitor, exhibited a classic monophasic organ response, whereas cyclandelate and sulindac showed biphasic suppression patterns. The latter indicate that there are metabolites of these drugs which possess aldose reductase inhibitory activities. The estimated potency of aldose reductase inhibition for each of the three drugs in this study was significantly discrepant from the in vitro studies indicating the complicated nature of the bioavailability of a pharmaceutical agent in vivo, especially where pharmacologically active metabolites of a given drug are involved. Our method allows for a direct quantitative assay and hence the most reliable technique for evaluating aldose reductase inhibitory activities in the target organ.
Rubidium transport in human erythrocyte suspensions monitored by 87rb NMR with aqueous chemical shift reagents
Authors: Helpern J. A. , Welch K. M. A. , Halvorson Herbert R. 
Published: March 2007

AbstractDysprosium(III) triethylenetraamine‐N,N,N′,N″,N‴,N‴‐hexaacetic acid (DyTTHA3–) was used as an aqueous chemical shift reagent in conjunction with high‐resolution nuclear magnetic resonance (NMR) spectroscopy to monitor 87‐rubidium (87Rb+) transport in human erythrocyte suspensions. NMR spectra demonstrated two resonances which were assigned to the intra‐ and extracellular compartments of the erythrocyte suspension. Uptake of 87Rb+ was shown to proceed via the [Na,K]‐ATPase dependent pump as evidenced by the inhibition of uptake in the presence of ouabain. The steady state intra‐ to extracellular concentration ratio of 87Rb was 3.00 and 1.13 in the absence and presence of ouabain, respectively. The rate of uptake of 87Rb+ in the absence and presence of ouabain was found to be 1.3 and 0.5 mmol Rb+/L erythrocytes/h at 18 mM Rb+, respectively. Data are also presented which indicate that the intracellular component of 18Rb is less than 100% NMR visible.
Maternal and cord blood plasma. Comparative analyses by 1H NMR spectroscopy
Authors: Bell Jimmy D. , Brown Judith C. C. , Sadler Peter J. , Garvie Dorothy , Macleod Andrew F. , Lowy Clara 
Published: March 2007

AbstractNormal and ‘Hahn’ spin‐echo 500 MHz 1H NMR spectra of 21 pairs of plasma from mother and cord taken at the time of delivery are reported. The concentrations of ‘NMR‐visible’ lactate, alanine, and valine in the cord plasma significantly exceed those in the maternal plasma. In both maternal and cord plasma, measured lactate levels appear to increase with the length of the second stage of labour. Ethanol was unexpectedly detected in five samples of cord plasma. Lipoprotein —CH3 and —(CH2)n— resonances are more intense in the spectra of maternal plasma compared to cord plasma, and are unusual in composition. The intensities of N‐acetyl signals from ‘acute‐phase’ plasma glycoproteins are greater in spin‐echo spectra of maternal plasma compared to those of cord plasma (mean ratio 2.1 (SD 0.8)). These results suggest that high resolution NMR spectroscopy may provide a useful new insight into the comparative biochemistry of maternal and cord plasma.
31P magnetic resonance spectroscopy of chronic cerebral infarction in rats
Authors: Houkin Kiyohiro , Nakada Tsutomu , Suzuki Nobuyuki , Kwee Ingrid L. 
Published: March 2007

AbstractThe chronological changes in the pattern of 31P magnetic resonance spectroscopy (MRS) associated with cerebral infarction were studied in rats. 31P MRS of chronic infarction (1 month after induction of infarction) clearly showed a pattern distinct from that of normal brain. In chronic infarction, the relative phosphomonoester (PME) level was found to be significantly higher and relative phosphocreatine (PCr) level significantly lower compared to normal brain. The intracellular pH and the relative inorganic phosphate (Pi) level did not show any significant differences. Histological examination indicated that the 31P MRS pattern of chronic infarction reflects gliosis.
Non‐Invasive determination of cerebral blood flow changes by 19f NMR spectroscopy
Authors: Rudin Markus , Sauter Andre 
Published: March 2007

AbstractThe build‐up and clearance of halothane in rat brain have been measured non‐invasively by 19F NMR spectroscopy using a surface coil placed on the intact scalp. When the halothane supply (3% in O2/N2O, 33/66%) was turned off, the 19F signal decreased exponentially to approximately 50% of the initial value, with a time constant, in normal rats, of 8.6 ± 0.7 min (mean ± SEM, n = 16), followed by a decay slower by at least one order of magnitude. The time constant of the rapid decay (r), which was found to be specific for brain, was reduced in hypoxic/hypercapnic (5% O2/5% CO2) rats to 2.9 ± 0.2 min (p = 0.001, n = 4), in rats infused with physostigmine (20 m̈/kg/min i.v.) to 5.7 ± 0.3 min (p = 0.005, n = 6) and increased in rats injected with pentothal (40 mg/kg i.p.) to 10.7 ± 1.6 min (p = 0.2, n = 5). Based on the theory of exchange of inert gas at the lungs and tissues developed by Kety, the rapid exponential decay of the 19F signal was used to calculate relative cerebral blood flow (CBF). Assuming the cortical CBF in a normal rat to be about 130 mL min–1 100 g–1, the following CBF values (means ± SEM) were obtained: controls 130 ± 10, hypoxia/hypercapnia 390 ± 59, hypercapnia 220 ± 25, physostigmine 195 ± 26, pentothal 105 ± 23 mL min–1 100 g–1. These values are in good agreement with published values obtained with established methods. The rate of halothane elimination in the lungs does not significantly influence the relative CBF values, since hypercapnia (pCO2 = 77–87) had the same effect on r in both mechanically ventilated and spontaneously breathing rats. It can be concluded that it is possible, using 19F NMR spectroscopy, to determine relative tissue perfusion rates accurately and non‐invasively, averaged over time and volume, in live animals by measuring the exponential disappearance of a 19F labelled inert gas, such as halothane.
NMR study on [1‐13C]glucose metabolism in the rat brain during hypoxia
Authors: Fujiwara Naoshi , Shimoji Koki , Yuasa Tatsuhiko , Igarashi Hironaka , Miyatake Tadashi 
Published: March 2007

AbstractThe metabolism of [1‐13C]glucose in the rat brain during hypoxia was investigated by 13C NMR spectroscopy. Male Wistar rats, weighing 100–120 g, were anesthetized with ketamine (50 ˜ 75 mg/kg i.p.) and ventilated mechanically with a mixture of 30% oxygen, 69.5% nitrogen and 0.5% halothane. [1‐13C]glucose (250 mg/kg) was infused twice, at 10 minute intervals, through the femoral vein. For the control group (n = 4), the oxygen concentration of the inspiratory gas was maintained at 30% by vol throughout the experiments. For the hypoxia group (n = 6), the oxygen concentration in the inspiratory gas was reduced to 6–7% (93–94% nitrogen) and maintained for 30 min following [1‐13C]glucose infusion. 13C NMR spectra were measured by a gated proton‐decoupling method without a nuclear Overhauser effect. The [1‐13C]glucose infusion gave apparent signals of the C1 carbon in the α‐ and β‐anomers of [1‐13C]glucose at 92.7 and 96.7 ppm, respectively. Signals of the C2, C3 and C4 carbon atoms in glutamate and/or glutamine (glx) also appeared at 55, 27 and 34 ppm, respectively. The intensity of glx‐C2 and glx‐C3 signals increased later than that of glx‐C4. The time lag between the different glx signals may reflect the turnover rate of the TCA cycle. Under the hypoxic condition, the signal of C3 carbon in lactate appeared at 21 ppm and increased. The α‐glucose signal diminished during hypoxia, whereas the β‐glucose signal kept its intensity. The difference in changes of the signal intensity between α‐ and β‐glucose suggests that α‐glucose is consumed more than β‐glucose in the hypoxic brain.
Broad resonance‐edited 31P spectra obtained with a single radiofrequency channel
Authors: Thoma William J. , Snyder John A. , Pearson Gerald A. 
Published: March 2007

AbstractThe broad phosphorus resonance of isolated perfused liver can be removed by selective presaturation with a DANTE pulse train. The use of the DANTE pulse allows the broad resonance to be removed without the use of multiple RF channels or the ability to switch the observation channel from low to high power.
Biochemical consequences of reflushing hypothermically‐stored liver with fresh cold perfusate. studies on rat liver using 31p NMR spectroscopy
Authors: Busza A. L. , Proctor E. , Fuller B. J. 
Published: March 2007

AbstractThe metabolic response of the rat liver to flushing and reflushing with Marshall's solution at pH 7.2 or pH 7.8 has been studied by 31P nuclear magnetic resonance spectroscopy. The changes in intracellular pH, inorganic phosphate, ATP and phosphomonoesters have been determined from the 31P spectra. We show that the intracellular pH at any stage of the flushing protocol is largely independent of the pH of the medium when using these solutions. However, we demonstrate that there are differences between the efficiency of the two solutions in respect of the rates of hydrolysis of ATP and accumulation of phosphomonoesters. There were also differences in the response of the livers upon reflushing—those livers reflushed at pH 7.2 resynthesized ATP from a lower initial concentration to achieve ATP concentrations similar to those restored in livers reflushed at pH 7.8. These trends were mirrored in the responses of the phosphomonoester peaks (which contain a contribution from AMP). We conclude that short‐term control of liver metabolism during hypothermia is possible by use of solutions of different pH, but that for longer‐term storage, other approaches may be necessary to maintain metabolic integrity.
Linear drive birdcage coil for 23Na human head studies at 1.5 T
Authors: Lim Kelvin O. , Wolff Steven , Balaban Robert S. 
Published: March 2007

AbstractProgress in the development of non‐proton NMR applications in medical research has been hampered by the generally low sensitivity of these nuclides as well as the lack of instrumentation readily available for studying these spins. For example, custom head coils suitable for sodium imaging of the human head are either not available or very expensive, making research startup costs high or impossible. Herein the detailed design and construction of a research 23Na head coil for MRI imaging is presented. 23Na NMR images collected with the coil are presented as well as a discussion of design modifications for other nuclides.