Phosphorus-31 Spectra Research Articles

High-resolution NMR correlation spectra of disordered solids.

We show how high-resolution NMR spectra can be obtained for solids for which the spectra are normally broadened due to structural disorder. The method relies on correlations in the chemical shifts between pairs of coupled spins. It is found experimentally that there are strong correlations in the chemical shifts between neighboring spins in both phosphorus-31 and carbon-13 spectra. These correlations can be exploited not only to provide resolution in two-dimensional spectra, but also to yield "chains" of correlated chemical shifts, constituting a valuable new source of structural information for disordered materials.

Improved preservation solutions for organ storage: a dynamic study of hepatic metabolism.

Organ cold storage times may be extended by modifications to organ preservation solutions. Three preservation solutions were investigated for their ability to maintain viable hepatic bioenergetics in stored pig livers: modified University of Wisconsin (mUW); mUW+adenosine (1.34 g/L), and mUW+ iloprost (10(-8)mol/L), a prostacyclin analogue. Using human liver retrieval and storage techniques, pig livers were stored on ice for either 2 or 16 hr, after which phosphorus-31 spectra were collected every 2 min during the period of cold ischemia and hypothermic reperfusion (HtR). During HtR, metabolite concentration changes associated with phosphomonoesters, inorganic phosphate, gamma-nucleotide triphosphate (NTP), and beta-NTP were measured for all solutions. After a 2-hr storage, beta-NTP regeneration in mUW+iloprost produced +57.7% (P<0.01) more beta-NTP, at a faster initial rate of +66.3% (P<0.001), compared with mUW, and mUW+adenosine regenerated +35.6% (P<0.05) more beta-NTP, compared with mUW. Storage for 16 hr did not slow the rates of regeneration, and the total NTP produced during the course of the experiment remained unchanged for the respective preservation solutions. Cessation of HtR invoked a net accumulation of nucleotide diphosphate, indicating differential kinetics of adenine nucleotide hydrolysis. This large animal model study suggests significant improvements to human organ preservation solutions using prostacyclin analogues and adenosine with respect to hepatic bioenergetics.

Evaluation of altered myocardial high energy phosphate metabolism in patients on maintenance dialysis using phosphorus-31 magnetic resonance spectroscopy.

Assessment of left ventricular metabolism and function is important in patients on maintenance dialysis because congestive heart failure occurs quite frequently and has a poor prognosis. The purpose of this study was to evaluate the changes of myocardial high energy metabolism in dialysis patients by using phosphorus-31 (31P) magnetic resonance (MR) spectroscopy. Phosphorus-31 spectra were obtained from anteroseptal wall of the heart in six normal subjects (mean age, 24 +/- 1 years) and 14 dialysis patients (mean age, 52 +/- 11 years), using a 1.5-tesla clinical MR system. Four patients had previous history of heart failure. Echocardiography was performed in all patients to evaluate left ventricular (LV) hypertrophy and LV function. The averaged ratio of phosphocreatine (PCr)/beta-adenosine triphosphate (beta-ATP) in dialysis patients (1.15 +/- 0.25 mean +/- standard deviation), was significantly lower than that in healthy subjects (1.63 +/- 0.21; P < 0.01). There was no significant difference in PCr/beta-ATP ratios between the non-LV hypertrophy group (1.21 +/- 0.24; n = 7) and the LV hypertrophy group (1.09 +/- 0.24; n = 7). The averaged PCr/beta-ATP ratio in four patients with history of heart failure (0.96 +/- 0.18) was significantly lower than that of the 10 patients without history of heart failure (1.22 +/- 0.23; P < 0.05). These results indicate that patients on maintenance dialysis have decreased PCr/beta-ATP ratio and 31P MR spectroscopy can provide noninvasive assessment of altered high energy phosphate metabolism.

The phosphorus-31 spectra of dielectrophoretically reoriented tubules in the H II phase of DOPE

31P electric field nuclear magnetic resonance measurements are described which assess the effect of electric field on the orientation of tubules comprising the H II phase of dioeleoylphosphatidylethanolamine. A model, based on dielectrophoretic effects, was used to predict that a field of 4 MV/m would change the orientation of the lipid tubules in a H II phase. The excitation pulse was biphasic to help discriminate electric field interactions with free ions or permanent dipoles from interactions with induced dipoles, as well as to control the problems of ohmic heating, electrolysis and polarisation associated with do or unbalanced ac excitation voltages. Spectra consistent with irreversible electrorotation and with reversible and transient electrorotation were observed. No response to the electric field was seen in certain cases. The conditions for irreversible and reversible electrorotation and failure to rotate have been tabulated and are discussed. Finally, some simple models are considered, in order to calculate the energies involved, if the observed NMR spectra are interpreted as arising from lipid H II phase reorientations.

The effect of pulsed electric fields on the phosphorus-31 spectra of lipid bilayers

A technique is described for measuring the effect of electric fields on the conformation of lipid bilayer membranes by solid state nuclear magnetic resonance. An apparatus was devised to obtain spectra from samples of aligned phospholipid dispersions at varying electric field strengths up to 100 MV/m. Measurements were carried out on membranes made from dioleoylphosphatidylethanolamine and dioleoylphosphatidylcholine, which resulted in electric field induced phase changes. Calibration experiments were performed using bilayers formed from dimyristoylphosphatidylcholine with glycerol and with a nematic liquid crystal. An electric field induced change, from L α to H II, was also seen in a dimyristoylphosphatidylcholine/alamethicin bilayer.

MR imaging as a potential diagnostic test for metabolic myopathies: importance of variations in the T2 of muscle with exercise.

Most metabolic myopathies (like glycogenoses and mitochondrial myopathies) are related to inborn errors of muscle energy metabolism and often present clinically as exercise intolerance (inability to sustain normal exercise). We investigated whether the previously observed absence of normal exercise-induced variation in the T2 of muscle in McArdle's disease (a metabolic myopathy caused by muscle phosphorylase deficiency) was specific for this disease and whether the variations in T2 could be used for screening patients suspected of having metabolic myopathy. Exercise-induced variations in proton MR signal and in intracellular pH were studied in the forearm flexor muscles of nine healthy subjects and 49 patients with exercise intolerance due to muscle pain, suggesting a metabolic myopathy. The relative increase in T2, delta T2/T2, was measured from MR spin-echo images before and after exercise. Phosphocreatine (used as a control of the degree of exercise) and intracellular pH were measured from phosphorus-31 spectra before and during exercise. The progressive 4.5-min handgrip exercise reached maximal exertion capability at the end of exercise and decreased phosphocreatine to less than 50% of its rest value. Variations in T2 and end-exercise pH were correlated. The nine healthy subjects showed a delta T2/T2 ranging from +19% to +44% (but little T1 variation). Ten patients with McArdle's disease showed only slight delta T2/T2 (0-10%). There was no overlap with values for healthy subjects, but there was some with values for other patients. Of the 21 subjects with a delta T2/T2 less than 19%, 19 had a metabolic myopathy. The other two had a congenital neuromuscular disorder (one central core disease, one nemaline myopathy) with type I fiber predominance (type I muscle fibers are characterized by a high oxidative metabolism and a low lactic acid production). The altered increase in T2 was sensitive but not specific for McArdle's disease. However, as variations in T2 reflect variations in pH, they seem to be specific for myopathies in which there is little exercise-induced decrease in pH (some metabolic myopathies and congenital neuromuscular disorders with type I fiber predominance) among patients in whom exercise intolerance is the main symptom. Our results suggest that MR imaging might be useful as a screening test for these diseases.

Physical training improves skeletal muscle metabolism in patients with chronic heart failure

Objectives. This study investigated the effects of physical training on skeletal muscle metabolism in patients with chronic heart failure.Background. Skeletal muscle metabolic abnormalities in patients with chronic heart failure have been associated with exercise intolerance. Muscle deconditioning is a possible mechanism for the intrinsic skeletal muscle metabolic changes seen in chronic heart failure.Methods. We used phosphorus-31 nuclear magnetic resonance spectroscopy to study muscle metabolism during exercise in 12 patients with stable ischemic chronic heart failure undergoing 8 weeks of home-based bicycle exercise training in a randomized crossover controlled trial. Changes in muscle pH and concentrations of phosphocreatine and adenosine diphosphate (ADP) were measured in phosphorus-31 spectra of calf muscle obtained at rest, throughout incremental work load plantar flexion until exhaustion and during recovery from exercise. Results were compared with those in 15 age-matched control subjects who performed a single study only.Results. Before training, phosphocreatine depletion, muscle acidification and the increase in ADP during the 1st 4 min of plantar flexion exercise were all increased (p < 0.04) compared with values in control subjects. Training produced an increase (p < 0.002) in incremental plantar flexion exercise tolerance. After training, phosphocreatine depletion and the increase in ADP during exercise were reduced significantly (p < 0.003) at all matched submaximal work loads and at peak exercise, although there was no significant change in the response of muscle pH to exercise. After training, changes in ADP were not significantly different from those in control subjects, although phosphocreatine depletion was still greater (p < 0.05) in trained patients than in control subjects. The phosphocreatine recovery half-time was significantly (p < 0.05) shorter after training, althrough there was no significant change in the half-time of adenosine diphosphate recovery. In untrained subjects, the initial rate of phosphocreatine resynthesis after exercise (a measure of the rate of oxidative adenosine triphosphate [ATP]synthesis) and the inferred maximal rate of mitochondrial ATP synthesis were reduced compared with rates in control subjects (p < 0.003) and both were significantly increased (p < 0.05) by training, so that they were not significantly different from values in control subjects.Conclusions. The reduction in phosphocreatine depletion and in the increase in ADP during exercise, and the enhanced rate of phosphocreatine resynthesis in recovery (which is independent of muscle mass) indicate that a substantial correction of the impaired oxidative capacity of skeletal muscle in chronic heart failure can be achieved by exercise training.

Quantitative P-31 MR spectroscopy of the liver in alcoholic cirrhosis.

To determine the cause of reduced urea synthesis in cirrhosis, absolute concentrations of phosphorus metabolites in the human liver have been measured in vivo with magnetic resonance (MR) spectroscopy. One-dimensional chemical shift imaging was used to obtain phosphorus-31 spectra from five healthy volunteers and five patients with alcoholic cirrhosis. A reference standard included in all studies enabled the calculation of absolute concentrations. In contrast to hepatic metabolite ratios, absolute concentrations reveal that in the cirrhotic patients, concentrations of adenosine triphosphate (ATP) were significantly reduced and concentrations of phosphomonoesters slightly reduced. Intracellular pH was unchanged. Histologic evidence suggests that the amount of ATP per cell was unchanged and could not account for the reduced urea production. Instead, urea synthesis depends on the functional liver cell mass, which was reduced by 31% in alcoholic cirrhosis. Quantitative in vivo P-31 MR spectroscopy of liver has potential clinical applications and can supplement the more generally used P-31 metabolite ratios.

Dynamic relation between myocardial contractility and energy metabolism during and following brief coronary occlusion in the pig.

Changes in high-energy phosphate metabolism may be important in the regulation of myocardial contractile function during ischemia. This study sought to determine the dynamic relation between myocardial contractile function and high-energy phosphate metabolism during and following brief (24-second) coronary occlusion, when large and rapid changes in both parameters occur. Eight anesthetized, open-chest pigs were instrumented with a Doppler flow probe and occluder on the anterior descending coronary artery, segment length crystals in the anterior left ventricular wall, and a surface coil for phosphorus-31 nuclear magnetic resonance spectroscopy. Phosphorus-31 spectra were reconstructed with a 4.8-second time resolution by summing corresponding short blocks of data from multiple occlusions. Metabolic and functional parameters were unchanged during the first 4.8 seconds of occlusion. During the remainder of occlusion, phosphocreatine progressively declined to 66 +/- 3% of control, inorganic phosphate rose to 170 +/- 8% of control, and segment shortening fell to 25 +/- 9% of control. A strong linear correlation was found between dynamic changes in segment shortening and phosphocreatine (r2 = 0.97), inorganic phosphate (r2 = 0.96), and the ratio of phosphocreatine to inorganic phosphate (r2 = 0.98) during occlusion. At any level of the ratio between phosphocreatine and inorganic phosphate, segment shortening was greater during reflow than during occlusion. The close, dynamic relation between segment shortening and phosphorus metabolites supports the regulation of contractility by changes in energy metabolism or its by-products during ischemia. During reactive hyperemia, the high coronary flow rate may be an independent factor modulating contractility.

PH standardization for phosphorus‐31 magnetic resonance heart spectroscopy at different temperatures

Intracellular pH typically is measured by NMR using the calibrated chemical shift of the inorganic phosphate peak in phosphorus-31 spectra. Heart spectroscopy experiments often require measurements of intracellular pH at temperatures from 5 to 37 degrees C. This paper provides NMR pH calibrations for this range of temperatures, a summary of calibration data reported to date, and a discussion of the factors influencing pH standardization.

Phosphorus-31, nitrogen-15, and nitrogen-14 nuclear magnetic resonance spectra of α-tetraphosphorus trisulphide isothiocyanates

Phosphorus-31 n.m.r. spectra of α-P4S3(NCS)2(1), α-P4S3(NCS)Cl (2), and α-P4S3(NCS)I (3) have been measured both for natural-abundance 14N isotopomers [(1a), (2a), and (3a)] and completely 15N-containing isotopomers [(1b), (2b), and (3b)] over a range of temperatures. Assignment and computer fitting of spectra of the 15N compounds has yielded accurate values of 31P–31P and 31P–15N coupling constants, and has allowed their variation with temperature to be studied. Measurement of 15N n.m.r. spectra [compounds (1b) and (3b)] has allowed the signs of the31P–15N couplings to be confirmed. A 14N T1 relaxation study of α-P4S3(14NCS)2(1a) showed a normal relaxation rate, and abnormal broadening in the 31P n.m.r. spectra of the 14N compounds was ascribed instead to the influence of abnormally large 1JPN coupling constants in the scalar coupling relaxation mechanism. Large 31P–15N coupling constants are reported for phosphorus(III) isothiocyanates, and for α-P4S3 derivatives. Similarly, large values of 1J(31P–13C) for α-P4S3(13CN)(12CN), and of the secondary isotope shifts 1Δ[31P(37/35Cl)] for α-P4S3(15NCS)Cl (2b) and α-P4S3Cl2, are reported.

Cardiovascular applications of nuclear magnetic resonance spectroscopy

Nuclear magnetic resonance spectroscopy has great potential for defining noninvasively the metabolic status of the heart and skeletal muscle. This technique uses the spin properties of certain nuclei (such as phosphorus-31, hydrogen-1 and carbon-13) to measure high energy phosphates, intracellular pH, lactate and glycogen. Animal studies have formed the basis for human investigations and have demonstrated well-defined changes in high energy phosphates during myocardial ischemia and reperfusion, as well as in cardiomyopathies. Human studies have been limited by issues of sensitivity and localization, although techniques such as rotating frame, depth-resolved surface coil spectroscopy, image-selected in vivo spectroscopy and spectroscopic imaging have been used to acquire phosphorus-31 spectra from the human heart. The few human studies of patients with disease have demonstrated elevated inorganic phosphate peaks after myocardial infarction and abnormal phosphodiester peaks in patients with hypertrophic cardiomyopathy. Studies of patients with heart failure have shown that these patients acidify their peripheral muscles with exercise more easily than do control subjects. Clinical application of nuclear magnetic resonance spectroscopy will depend on technical advances and the demonstration of sensitivity of metabolic changes with disease.

A cylindrical-window NMR probe with extended tuning range for studies of the developing heart

Three matched cylindrical-window NMR probes were designed and constructed in graduated sizes (16, 25, and 30 mm) for neonatal, immature, and adult heart spectroscopy. The cylindrical probes were made of copper foil and had two symmetrical cylindrical conductive blades separated by openings subtending 90° arcs. The tuning range included both sodium-23 (52.9 MHz) and phosphorus-31 (81.0 MHz). The ability to tune to sodium-23 expedited shimming for phosphorus-31 experimental measurements. Standardization of phosphorus-31 spectra was achieved with an MDPA-filled capillary tube placed outside the cylindrical window. The finite element method was used to derive the electrical potential, magnetic field, and current densities. B 1 field mappings showed uniformity throughout the usable areas, an attribute facilitating comparisons of spectra from hearts of different sizes. We summarize the current designs for low-inductance NMR probes of this type.

Gated cardiac MR imaging and P-31 MR spectroscopy in humans at 1.5 T. Work in progress.

The authors describe a technique to acquire gated cardiac proton magnetic resonance images and localized hydrogen-1 and phosphorus-31 spectra with a doubly tuned surface coil probe. The probe reduces study time because the need to exchange imaging and spectroscopy coils is eliminated, while at the same time the sensitivity of singly tuned coils is retained. In addition, the probe enhances the ability of the investigator to localize cardiac spectra spatially and temporally during the cardiac cycle. Spectra were acquired from the left ventricular myocardium in five volunteers, and systolic and diastolic gated P-31 spectra were shown.

Nuclear magnetic resonance imaging-guided phosphorus-31 spectroscopy of the human heart

Phosphorus-31 nuclear magnetic resonance spectroscopy can determine the status of high energy phosphates in vivo. However, its application to human cardiac studies requires precise spatial localization without significant contamination from other tissues. Using image-selected in-vivo spectroscopy (ISIS), a technique that allows three-dimensional localization of the volume of interest, 12 subjects were studied to determine the feasibility and reproducibility of phosphorus-31 spectroscopy of the human heart. Nuclear magnetic resonance imaging was performed using a commercial 1.5 tesla system to define the volume of interest. Phosphorus-31 spectra were obtained from the septum and anteroapical region of the left ventricle in 10 studies. Relative peak heights and areas were determined for high energy phosphates. The mean phosphocreatine to adenosine triphosphate ratio was 1.33 +/- 0.19 by height analysis and 1.23 +/- 0.27 by area analysis. Duplicate measurements in four subjects showed a reproducibility of less than or equal to 10% in three of the subjects. All spectra showed significant signal contribution from the 2,3 diphosphoglycerate in chamber red cells without evidence of skeletal muscle contamination. These results demonstrate the feasibility of image-guided phosphorus-31 spectroscopy for human cardiac studies and indicate the potential of this technique to study metabolic disturbances in human myocardial disease.

Indirect two-dimensional heteronuclear NMR spectroscopy. Phosphorus-31 and iron-57 spectra of organoiron complexes

The indirect heteronuclear two-dimensional (2D) triple-resonance (S,I)-(/sup 1/H) NMR spectroscopy is introduced for measuring the chemical shift and scalar spin-spin coupling constants of an insensitive nucleus I via its scalar coupling J(S,I) by detection of the nucleus S of higher sensitivity. The versatility of this approach is demonstrated by extracting delta(/sup 57/Fe) and J(Fe,X) from (/sup 31/P,/sup 57/Fe)-(/sup 1/H) spectra of various dissolved ((/eta//sup 5/-Cp)(L/sub 2/(R)))Fe, ((/eta//sup 3/-allyl)(/eta//sup 5/-Cp)(L))Fe, and ((/eta//sup 1/,/eta//sup 2/-alkenyl)(/eta//sup 5/-Cp)(L))Fe complexes (R = alkyl, hydride; L = PR/sub 3/). In practice the sensitivity of 2D (/sup 31/P,/sup 57/Fe) spectra was found to be higher than that of the direct observation scheme by at least a factor (..gamma../sub P//..gamma../sub Fe/)/sup 5/2/. Due to the intrinsically higher resolving power of a two-dimensional experiment, small scalar couplings like /sup 2J/(Fe,F) and /sup 1/J(Fe,H) were readily obtained from indirect two-dimensional spectra. Combinations of (/sup 1/H,/sup 57/Fe) and (/sup 31/P,/sup 57/Fe) spectra yielded the relative signs of the J(Fe,X) couplings: /sup 1/J(Fe,P) is positive and increases with increasing ..pi..-acceptor power of the phosphorus ligand L from 55 (L = PMe/sub 3/, R = H) to 149 Hz (L = PF/sub 3/). /sup 1/J(Fe,H) is around +9 Hz (R = H), whereasmore » /sup 2/J(P,H) in these complexes was found to be negative. In all of the allyl complexes investigated, /sup 2J/(Fe,F) (L = PF/sub 3/) is positive and around 3 Hz. In the quasi-tetragonal and -trigonal iron complexes, delta(/sup 57/Fe) varies by about 4000 ppM. This can be rationalized qualitatively by the electronegativity of the atoms directly bonded to iron and the higher oxidation potential in the presence of more basic ligands L via the paramagnetic shielding term. 52 references, 5 figures, 5 tables.« less

Line narrowing in phosphorus-31 spectra of solids using a combination of high-power decoupling, cross-polarization, magic-angle spinning, and 31P multiple-pulse operation

Line narrowing in phosphorus-31 spectra of solids using a combination of high-power decoupling, cross-polarization, magic-angle spinning, and 31P multiple-pulse operation

Phosphorus-31 magnetic resonance spectroscopy of experimentally induced arthritis in rats.

Phosphorus-31 magnetic resonance spectroscopy (MRS) of the hind paws of rats was performed at 1.5 Tesla before and during the course of an experimentally-induced inflammatory arthritis. Arthritis was induced by daily subcutaneous administration of 6-sulfanilamidoindazole, an antibacterial sulfa known to produce an acute, self-limited arthritis and periarthritis in the hind paws of rats. Phosphorus-31 spectra obtained after the development of clinical arthritis showed a significant (p less than 0.01) increase in the intensity of a group of resonances occurring downfield from phosphocreatine as compared to spectra obtained before treatment. In all rats, this increase correlated well with histological evidence of inflammation as well as with the degree of inflammation judged clinically (r = 0.89, p less than 0.001), and was present before roentgenographic evidence of bony involvement. The use of 31P MRS may permit evaluation of the severity of an inflammatory arthritis with greater accuracy than the bony changes definable by plain roentgenograms.

The study of human organs by phosphorus-31 topical magnetic resonance spectroscopy.

The potential clinical use of topical magnetic resonance spectroscopy (volume selection by static magnetic field gradients) was tested in 50 studies in volunteers. Topical magnetic resonance spectroscopy (MRS) was shown to be a straightforward method for localising 31P spectra of brain and liver. However, the spherical shape and fixed position of the selected volume posed serious limitations to the study of heart and transplanted kidney by topical MRS. Phosphorus-31 spectra of approximately 30 cm-3 of brain or liver could be obtained in 8 min. Ratios of metabolite concentrations could be determined with a coefficient of variation ranging from 10% to 30%. The ratios of phosphocreatine/ATP and inorganic phosphate/ATP in brain were 1.8 and 0.3, respectively. The ratio of inorganic phosphate/ATP in liver was 0.9. Intracellular pH was 7.03 in brain and 7.24 in liver. The T1 relaxation times of phosphocreatine, inorganic phosphate and gamma-ATP in brain were 4.8 s, 2.5 s and 1.0 s, respectively.

A general procedure for assigning the phosphorus-31 spectra of nucleic acids

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTA general procedure for assigning the phosphorus-31 spectra of nucleic acidsAndrew P. Joseph and Philip H. BoltonCite this: J. Am. Chem. Soc. 1984, 106, 2, 437–439Publication Date (Print):January 1, 1984Publication History Published online1 May 2002Published inissue 1 January 1984https://doi.org/10.1021/ja00314a039RIGHTS & PERMISSIONSArticle Views25Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (435 KB) Get e-Alerts Get e-Alerts