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Purvis LAB, Clarke WT, Valkovič L, Levick C, Pavlides M, Barnes E, Cobbold JF, Robson MD, Rodgers CT. Phosphodiester content measured in human liver by in vivo 31 P MR spectroscopy at 7 tesla. Magn Reson Med 2017; 78:2095-2105. [PMID: 28244131 PMCID: PMC5697655 DOI: 10.1002/mrm.26635] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 01/13/2017] [Accepted: 01/17/2017] [Indexed: 12/19/2022]
Abstract
Purpose Phosphorus (31P) metabolites are emerging liver disease biomarkers. Of particular interest are phosphomonoester and phosphodiester (PDE) “peaks” that comprise multiple overlapping resonances in 31P spectra. This study investigates the effect of improved spectral resolution at 7 Tesla (T) on quantifying hepatic metabolites in cirrhosis. Methods Five volunteers were scanned to determine metabolite T1s. Ten volunteers and 11 patients with liver cirrhosis were scanned at 7T. Liver spectra were acquired in 28 min using a 16‐channel 31P array and 3D chemical shift imaging. Concentrations were calculated using γ‐adenosine‐triphosphate (γ‐ATP) = 2.65 mmol/L wet tissue. Results T1 means ± standard deviations: phosphatidylcholine 1.05 ± 0.28 s, nicotinamide‐adenine‐dinucleotide (NAD+) 2.0 ± 1.0 s, uridine‐diphosphoglucose (UDPG) 3.3 ± 1.4 s. Concentrations in healthy volunteers: α‐ATP 2.74 ± 0.11 mmol/L wet tissue, inorganic phosphate 2.23 ± 0.20 mmol/L wet tissue, glycerophosphocholine 2.34 ± 0.46 mmol/L wet tissue, glycerophosphoethanolamine 1.50 ± 0.28 mmol/L wet tissue, phosphocholine 1.06 ± 0.16 mmol/L wet tissue, phosphoethanolamine 0.77 ± 0.14 mmol/L wet tissue, NAD+ 2.37 ± 0.14 mmol/L wet tissue, UDPG 2.00 ± 0.22 mmol/L wet tissue, phosphatidylcholine 1.38 ± 0.31 mmol/L wet tissue. Inorganic phosphate and phosphatidylcholine concentrations were significantly lower in patients; glycerophosphoethanolamine concentrations were significantly higher (P < 0.05). Conclusion We report human in vivo hepatic T1s for phosphatidylcholine, NAD+, and UDPG for the first time at 7T. Our protocol allows high signal‐to‐noise, repeatable measurement of metabolite concentrations in human liver. The splitting of PDE into its constituent peaks at 7T may allow more insight into changes in metabolism. Magn Reson Med 78:2095–2105, 2017. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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Affiliation(s)
- Lucian A B Purvis
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom
| | - William T Clarke
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom
| | - Ladislav Valkovič
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom.,Department of Imaging Methods, Institute of Measurement Science, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Christina Levick
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom
| | - Michael Pavlides
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom.,Translational Gastroenterology Unit, University of Oxford, United Kingdom
| | - Eleanor Barnes
- Translational Gastroenterology Unit, University of Oxford, United Kingdom
| | - Jeremy F Cobbold
- Translational Gastroenterology Unit, University of Oxford, United Kingdom
| | - Matthew D Robson
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom
| | - Christopher T Rodgers
- Oxford Centre for Clinical Magnetic Resonance Research (OCMR), University of Oxford, Level 0, John Radcliffe Hospital, Oxford, United Kingdom
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van der Kemp WJM, Stehouwer BL, Runge JH, Wijnen JP, Nederveen AJ, Luijten PR, Klomp DWJ. Glycerophosphocholine and Glycerophosphoethanolamine Are Not the Main Sources of the In Vivo (31)P MRS Phosphodiester Signals from Healthy Fibroglandular Breast Tissue at 7 T. Front Oncol 2016; 6:29. [PMID: 26913240 PMCID: PMC4753293 DOI: 10.3389/fonc.2016.00029] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2015] [Accepted: 01/28/2016] [Indexed: 11/13/2022] Open
Abstract
PURPOSE The identification of the phosphodiester (PDE) (31)P MR signals in the healthy human breast at ultra-high field. METHODS In vivo (31)P MRS measurements at 7 T of the PDE signals in the breast were performed investigating the chemical shifts, the transverse- and the longitudinal relaxation times. Chemical shifts and transverse relaxation times were compared with non-ambiguous PDE signals from the liver. RESULTS The chemical shifts of the PDE signals are shifted -0.5 ppm with respect to glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE), and the transverse and longitudinal relaxation times for these signals are a factor 3 to 4 shorter than expected for aqueous GPC and GPE. CONCLUSION The available experimental evidence suggests that GPC and GPE are not the main source of the PDE signals measured in fibroglandular breast tissue at 7 T. These signals may predominantly originate from mobile phospholipids.
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Affiliation(s)
| | | | - Jurgen H Runge
- Radiology, Academic Medical Center , Amsterdam , Netherlands
| | - Jannie P Wijnen
- Radiology, University Medical Center Utrecht , Utrecht , Netherlands
| | | | - Peter R Luijten
- Radiology, University Medical Center Utrecht , Utrecht , Netherlands
| | - Dennis W J Klomp
- Radiology, University Medical Center Utrecht , Utrecht , Netherlands
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Chmelik M, Považan M, Krššák M, Gruber S, Tkačov M, Trattnig S, Bogner W. In vivo (31)P magnetic resonance spectroscopy of the human liver at 7 T: an initial experience. NMR IN BIOMEDICINE 2014; 27:478-85. [PMID: 24615903 DOI: 10.1002/nbm.3084] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2012] [Revised: 12/11/2013] [Accepted: 01/07/2014] [Indexed: 05/12/2023]
Abstract
Phosphorus ((31) P) MRS is a powerful tool for the non-invasive investigation of human liver metabolism. Four in vivo (31) P localization approaches (single voxel image selected in vivo spectroscopy (3D-ISIS), slab selective 1D-ISIS, 2D chemical shift imaging (CSI), and 3D-CSI) with different voxel volumes and acquisition times were demonstrated in nine healthy volunteers. Localization techniques provided comparable signal-to-noise ratios normalized for voxel volume and acquisition time differences, Cramer-Rao lower bounds (8.7 ± 3.3%1D-ISIS , 7.6 ± 2.5%3D-ISIS , 8.6 ± 4.2%2D-CSI , 10.3 ± 2.7%3D-CSI ), and linewidths (50 ± 24 Hz1D-ISIS , 34 ± 10 Hz3D-ISIS , 33 ± 10 Hz2D-CSI , 34 ± 11 Hz3D-CSI ). Longitudinal (T1 ) relaxation times of human liver metabolites at 7 T were assessed by 1D-ISIS inversion recovery in the same volunteers (n = 9). T1 relaxation times of hepatic (31) P metabolites at 7 T were the following: phosphorylethanolamine - 4.41 ± 1.55 s; phosphorylcholine - 3.74 ± 1.31 s; inorganic phosphate - 0.70 ± 0.33 s; glycerol 3-phosphorylethanolamine - 6.19 ± 0.91 s; glycerol 3-phosphorylcholine - 5.94 ± 0.73 s; γ-adenosine triphosphate (ATP) - 0.50 ± 0.08 s; α-ATP - 0.46 ± 0.07 s; β-ATP - 0.56 ± 0.07 s. The improved spectral resolution at 7 T enabled separation of resonances in the phosphomonoester and phosphodiester spectral region as well as nicotinamide adenine dinucleotide and uridine diphosphoglucose signals. An additional resonance at 2.06 ppm previously assigned to phosphoenolpyruvate or phosphatidylcholine is also detectable. These are the first (31) P metabolite relaxation time measurements at 7 T in human liver, and they will help in the exploration of new, exciting questions in metabolic research with 7 T MR.
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Affiliation(s)
- Marek Chmelik
- High Field MR Centre, Department of Biomedical Imaging and Image-Guided Therapy, Medical University of Vienna, Vienna, Austria
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Evaluation of Early Imaging Response After Chemoembolization of Hepatocellular Carcinoma by Phosphorus-31 Magnetic Resonance Spectroscopy—Initial Experience. J Vasc Interv Radiol 2011; 22:1166-73. [DOI: 10.1016/j.jvir.2011.04.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2010] [Revised: 04/04/2011] [Accepted: 04/11/2011] [Indexed: 11/21/2022] Open
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Wong GKC, Yeung DKW, Ahuja AT, King AD, Lam CWK, Chan MTV, Gin T, Poon WS. Intracellular free magnesium of brain and cerebral phosphorus-containing metabolites after subarachnoid hemorrhage and hypermagnesemic treatment: a 31P–magnetic resonance spectroscopy study. J Neurosurg 2010; 113:763-9. [DOI: 10.3171/2009.10.jns09915] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
Disturbance of cerebral phosphorus-containing metabolites occurs in many disease entities and has not been widely studied in patients with subarachnoid hemorrhage (SAH). Pilot studies have indicated that hypermagnesemic treatment may improve outcome in patients with aneurysmal SAH, but the precise mechanism is not known. The authors hypothesized that, by raising intracellular brain free magnesium in aneurysmal SAH, hypermagnesemic treatment would alter the cerebral energy status.
Methods
The authors designed the current study to use 31P-MR spectroscopy (MRS) to investigate intracellular brain free magnesium and cerebral phosphorus-containing metabolites in patients with good-grade aneurysmal SAH, both those receiving and not receiving hypermagnesemic therapy. A total of 37 eligible patients and 23 healthy volunteers were recruited. A total of 81 MRS studies were performed.
Results
Hypermagnesemic treatment after aneurysmal SAH produced a small (mean difference 0.018 ± 0.007 mM [+ 13.0%]) but significant elevation of intracellular free magnesium during the 1st week. Aneurysmal SAH produced a depressed membrane metabolism with lower phosphodiester/total phosphate.
Conclusions
The MRS finding of elevated brain free intracellular magnesium after intravenous magnesium sulfate infusion is novel, and the changes in membrane metabolism provide insight into the metabolic effects of aneurysmal SAH and future pathophysiological studies.
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Affiliation(s)
| | | | - Anil T. Ahuja
- 2Departments of Diagnostic Radiology and Organ Imaging,
| | - Ann D. King
- 2Departments of Diagnostic Radiology and Organ Imaging,
| | - Christopher W. K. Lam
- 4Chemical Pathology, Prince of Wales Hospital, The Chinese University of Hong Kong, China
| | | | - Tony Gin
- 3Anaesthesia and Intensive Care, and
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Corbin IR, Ryner LN, Singh H, Minuk GY. Quantitative hepatic phosphorus-31 magnetic resonance spectroscopy in compensated and decompensated cirrhosis. Am J Physiol Gastrointest Liver Physiol 2004; 287:G379-84. [PMID: 15191882 DOI: 10.1152/ajpgi.00418.2003] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Few studies have examined the physiological/biochemical status of hepatocytes in patients with compensated and decompensated cirrhosis in situ. Phosphorus-31 magnetic resonance spectroscopy ((31)P MRS) is a noninvasive technique that permits direct assessments of tissue bioenergetics and phospholipid metabolism. Quantitative (31)P MRS was employed to document differences in the hepatic metabolite concentrations among patients with compensated and decompensated cirrhosis as well as healthy controls. All MRS examinations were performed on a 1.5-T General Electric Signa whole body scanner. The concentration of hepatic phosphorylated metabolites among patients with compensated cirrhosis (n = 7) was similar to that among healthy controls (n = 8). However, patients with decompensated cirrhosis (n = 6) had significantly lower levels of hepatic ATP compared with patients with compensated cirrhosis and healthy controls (P < 0.02 and P < 0.009, respectively) and a higher phosphomonoester/phosphodiester ratio than controls (P < 0.003). The results of this study indicate that metabolic disturbances in hepatic energy and phospholipid metabolism exist in patients with decompensated cirrhosis that are not present in patients with compensated cirrhosis or healthy controls. These findings provide new insights into the pathophysiology of hepatic decompensation.
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Affiliation(s)
- I R Corbin
- John Buhler Research Centre, 803F-715 McDermot Ave., Winnipeg, Manitoba, Canada.
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Stanley JA. In vivo magnetic resonance spectroscopy and its application to neuropsychiatric disorders. CANADIAN JOURNAL OF PSYCHIATRY. REVUE CANADIENNE DE PSYCHIATRIE 2002; 47:315-26. [PMID: 12025430 DOI: 10.1177/070674370204700402] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In vivo magnetic resonance spectroscopy (MRS) is the only noninvasive imaging technique that can directly assess the living biochemistry in localized brain regions. In the past decade, spectroscopy studies have shown biochemical alterations in various neuropsychiatric disorders. These first-generation studies have, in most cases, been exploratory but have provided insightful biochemical information that has furthered our understanding of different brain disorders. This review provides a brief description of spectroscopy, followed by a literature review of key spectroscopy findings in schizophrenia, affective disorders, and autism. In schizophrenia, phosphorus spectroscopy studies have shown altered metabolism of membrane phospholipids (MPL) during the early course of the illness, which is consistent with a neurodevelopmental abnormality around the critical period of adolescence when the illness typically begins. Children and adolescents who are at increased genetic risk for schizophrenia show similar MPL alterations, suggesting that schizophrenia subjects with a genetic predisposition may have a premorbid neurodevelopmental abnormality. Independent of medication status, bipolar subjects in the depressive state tended to have higher MPL precursor levels and a deficit of high-energy phosphate metabolites, which also is consistent with major depression, though these results varied. Further bipolar studies are needed to investigate alterations at the early stage. Lastly, associations between prefrontal metabolism of high-energy phosphate and MPL and neuropsychological performance and reduced N-acetylaspartate in the temporal and cerebellum regions have been reported in individuals with autism. These findings are consistent with developmental alterations in the temporal lobe and in the cerebellum of persons with autism. This paper discusses recent findings of new functions of N-acetylaspartate.
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Affiliation(s)
- Jeffrey A Stanley
- Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh Medical Center, Pittsburgh, Pennsylvania, USA.
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Stanley JA, Pettegrew JW. Postprocessing method to segregate and quantify the broad components underlying the phosphodiester spectral region of in vivo (31)P brain spectra. Magn Reson Med 2001; 45:390-6. [PMID: 11241695 DOI: 10.1002/1522-2594(200103)45:3<390::aid-mrm1051>3.0.co;2-d] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
In a typical, in vivo (31)P brain spectrum, the phosphomonoester (PME) and phosphodiester (PDE) spectral region not only contains signals from freely mobile PMEs and PDEs (which are anabolic and catabolic products of membrane phospholipids) but also signals of broader underlying lineshapes from less-mobile molecules. In general, either the PME and PDE resonances are quantified as a combined value of freely mobile metabolites plus less-mobile molecules or the broader underlying signal is reduced/eliminated prior to or post data collection. In this study, a postprocessing method that segregates and quantifies the individual contributions of the freely mobile metabolites and the less-mobile molecules is introduced. To demonstrate the precision and accuracy of the method, simulated data and in vivo (31)P brain spectroscopy data of healthy individuals were quantified. The ability to segregate and quantify these various PME and PDE contributions provides additional spectral information and improves the accuracy of the interpretation of (31)P spectroscopy results. Magn Reson Med 45:390-396, 2001.
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Affiliation(s)
- J A Stanley
- Neurophysics Laboratory, Department of Psychiatry, Western Psychiatric Institute and Clinic, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, USA.
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Magee LA, Dixon RM, Kemp GJ, Redman CW, Styles P. 31P magnetic resonance spectroscopy of the liver in HELLP syndrome. BRITISH JOURNAL OF OBSTETRICS AND GYNAECOLOGY 1999; 106:582-8. [PMID: 10426617 DOI: 10.1111/j.1471-0528.1999.tb08328.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
OBJECTIVES Using magnetic resonance spectroscopy (MRS) to measure phosphorus-containing metabolites in the liver, this study aimed to investigate non-invasively whether or not women with haemolysis, elevated liver enzymes and low platelets (HELLP) have detectable abnormalities of hepatic energetics. SETTING John Radcliffe Hospital, Oxford. DESIGN Prospective study. METHODS After giving informed consent, patients with HELLP syndrome (n = 7) and controls with severe pre-eclampsia (n = 3), were studied by 31P MRS of the liver as soon as possible after delivery (range 2-4 days) and compared with normal nonpregnant controls (n = 6). Haematological and biochemical tests were performed serially and on the day of the MRS in all pregnant patients. RESULTS The severity of HELLP varied as follows: peak aspartate aminotransferase (range 129-2574), peak gamma glutamyl transferase (range 28-96), peak lactate dehydrogenase (range 305-2820), nadir platelets (range 25-114), peak international normalised ratio for prothrombin time (before fresh frozen plasma) (range 0.9-1.9). One pregnancy was terminated but all others resulted in live births and all mothers made uneventful, rapid recoveries. MRS-determined relative hepatic concentrations of phosphorus-containing metabolites and absolute concentrations of adenosine triphosphate did not differ significantly between groups. One patient with the most clinically severe HELLP syndrome (by laboratory criteria) exhibited magnetic resonance spectra which showed a relative increase in phosphomonoester and an absolute decrease in hepatic adenosine triphosphate (to 62% of control). CONCLUSIONS Enthusiasm for the conservative management of HELLP syndrome that develops remote from term has been tempered by the inability to identify patients at risk for progression to hepatic necrosis. We found that most patients with HELLP syndrome had normal liver metabolism as assessed by MRS. However, clinically severe HELLP syndrome can be associated with disturbed hepatic metabolism consistent with that seen in hepatic ischaemia and/or granulocytic infiltration of the liver.
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Affiliation(s)
- L A Magee
- Nuffield Department of Obstetrics and Gynaecology, John Radcliffe Hospital, Oxford, UK
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Bruynseels K, Bergans N, Gillis N, van Dorpen F, Van Hecke P, Stalmans W, Vanstapel F. On the inhibition of hepatic glycogenolysis by fructose. A 31P-NMR study in perfused rat liver using the fructose analogue 2,5-anhydro-D-mannitol. NMR IN BIOMEDICINE 1999; 12:145-156. [PMID: 10414949 DOI: 10.1002/(sici)1099-1492(199905)12:3<145::aid-nbm559>3.0.co;2-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Inhibition of hormone-stimulated hepatic glycogenolysis by fructose (Fru) has been attributed to accumulation of the competitive inhibitor Fru1P and/or to the associated depletion of the substrate phosphate (Pi). To evaluate the relative importance of either factor, we used the Fru analogue 2,5-anhydro-D-mannitol (aHMol). This analogue is avidly phosphorylated, traps Pi, and inhibits hormone-stimulated glycogenolysis, but it is not a gluconeogenic substrate, and hence does not confound glycogenolytic glucose production. Livers were continuously perfused with dibutyryl-cAMP (100 microM) to clamp phosphorylase in its fully activated a form. We administered aHMol (3.8 mM), and studied changes in glycogenolysis (glucose, lactate and pyruvate output) and in cytosolic Pi and phosphomonoester (PME), using in situ 31P-NMR spectroscopy (n = 4). Lobes of seven livers perfused outside the magnet were extracted for evaluation, by high-resolution 31P-NMR, of the evolution of aHMol1P and of aHMol(1,6)P2. After addition of aHMol, both glycogenolysis and the NMR Pi signal dropped precipitously, while the PME signal rose continuously and was almost entirely composed of aHMol1P. Inhibition of glycogenolysis in excess of the drop in Pi could be explained by continuing accumulation of aHMol1P. A subsequent block of mitochondrial ATP synthesis by KCN (1 mM) caused a rapid increase of Pi. Despite recovery of Pi to values exceeding control levels, glycogenolysis only recovered partially, attesting to the Pi-dependence of glycogenolysis, but also to inhibition by aHMol phosphorylation products. However, KCN resulted in conversion of the major part of aHMol1P into aHMol(1,6)P2. Residual inhibition of glycogenolysis was due to aHMol1P. Indeed, the subsequent withdrawal of aHMol caused a further gradual decrease in the proportion of aHMol1P (being converted into aHMol(1,6)P2, in the absence of de novo aHMol1P synthesis), and this resulted in a gradual de-inhibition of glycogenolysis, in the absence of marked changes in Pi. Glycogenolytic rates were consistently predicted by a model assuming non-saturated Pi kinetics and competition by aHMol1P exclusively: In conclusion, limited Pi availability and the presence of competitive inhibitors are decisive factors in the control of the in situ catalytic potential of phosphorylase a.
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Affiliation(s)
- K Bruynseels
- Biomedical NMR Unit, Department of Radiology, Leuven, Belgium
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Abstract
Technologic advances in functional brain imaging have provided exciting and informative insights into the functional neuroanatomy and neurochemistry of schizophrenia. Using MR spectroscopy, it has been possible to examine in vivo brain metabolism and to relate observed changes to physiological processes occurring at a cellular level. Positron emission tomography and single photon emission computed tomography have revealed disturbances of cerebral blood flow and glucose metabolism in patients with schizophrenia. More recently, these tools have also proved most useful in studying the relative receptor occupancy of typical and atypical antipsychotic medications.
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Affiliation(s)
- R J McClure
- Department of Psychiatry, University of Pittsburgh Medical Center, Pennsylvania, USA
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Wasser JS, Vogel L, Guthrie SS, Stolowich N, Chari M. 31P-NMR determinations of cytosolic phosphodiesters in turtle hearts. COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART A, PHYSIOLOGY 1997; 118:1193-200. [PMID: 9505428 DOI: 10.1016/s0300-9629(97)00046-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
As part of our ongoing research on cardiac hypoxia tolerance we have conducted 31P nuclear magnetic resonance (NMR) studies of isolated, perfused, working hearts from freshwater turtles, animals that are well known for their ability to tolerate prolonged periods of anoxia. A striking feature of turtle heart spectra is an extremely high concentration of NMR visible phosphodiesters (PDEs). Cardiac spectra from mammals, on the other hand, typically exhibit only a small resonance in the PDE region. Our aim in this study was to compare myocardial PDE profiles between the highly hypoxia tolerant western painted turtle (Chrysemys picta bellii) and the relatively hypoxia sensitive softshelled turtle (Trionyx spinifer) in order to begin to rest the hypothesis that high constitutive levels of cytosolic PDEs may play a role in conferring hypoxia and ischemia tolerance on the myocardium. We also collected 31P-NMR spectra of PCA extracts of tissue from these species and from Kemp's ridley sea turtles (Lepidochelys kempi), as well as spectra from isolated hearts and PCA extracts of red-eared sliders (Trachemys [formerly Pseudemys] scripta]). Total NMR visible phosphodiesters make up 24 +/- 8.6% of the total NMR visible phosphorus in Chrysemys hearts, 20.7 +/- 5.9% in Trachemys hearts, but only 12.2 +/- 5.1% in Trionyx hearts (P < 0.05). We have identified three distinct PDEs in turtle hearts: glycerophosphorylcholine (GPC); glycerophosphorylethanolamine (GPE); and serine ethanolamine phosphodiester (SEP). SEP is the dominant compound in Chrysemys and Trachemys (79.3 +/- 10.2% and 84.7 +/- 3.7% of total PDE, respectively), while GPC is most abundant in Trionyx (74.0 +/- 4.3% of total PDE) and Lepidochelys (not quantitated). The function of this class of compounds is unclear but it has been suggested that cytosolic PDEs may function as lysophospholipase inhibitors, a role that would decrease the rate of membrane phospholipid turnover. Our comparative data suggest that cytosolic PDEs could play a role in phospholipid sparing during anoxic or ischemic stress in turtles but a direct test of this hypothesis awaits future experimentation.
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Affiliation(s)
- J S Wasser
- Department of Veterinary Physiology & Pharmacology, College of Veterinary Medicine, Texas A&M University, College Station 77843-4466, USA.
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Bruynseels K, Gillis N, Van Hecke P, Vanstapel F. Phosphonates as 31P-NMR markers of extra- and intracellular space and pH in perfused rat liver. NMR IN BIOMEDICINE 1997; 10:263-270. [PMID: 9449129 DOI: 10.1002/(sici)1099-1492(199709)10:6<263::aid-nbm472>3.0.co;2-j] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We evaluated phosphonates (Po) as markers of the extra- and intracellular space in perfused rat liver. (i) In- and outwash behaviour of phenylphosphonate (PhePo), 3-amino-propylphosphonate (NProPo) and methyl phosphonate (MePo) was compared with that of creatine phosphate (CrP), a marker of the extracellular space, and of dimethyl methylphosphonate (MePoMe2), a marker of the total water-accessible space. In- and outwash of CrP was accurately predicted by the time constant (approximately 12 s) for the in- and outwash of inulin, a standard marker of the extracellular space. MePoMe2 rapidly distributed over the total liver volume (about three times the CrP accessible space). PhePo, NProPo and MePo washed rapidly into the extracellular space with CrP, and then steadily spilled over into the MePoMe2-accessible space. Upon outwash, Po signals rapidly declined in phase with that of CrP. Residual Po (PhePo >> NProPo approximately equal to MePo) reflected the amount internalized during prolonged (60 min) inwash. Proportional amounts of residual Po were found in extracts of livers harvested after outwash of perfusate and extracellular markers. Consistent with exclusion from the cells, CrP went undetected in these extracts. (ii) The resonance frequency of residual PhePo after outwash of the extracellular fraction corresponded with the pH reported by cytosolic P1 and responded to transient changes of the intracellular pH, induced by perfusion with and withdrawal of 20 mM NH4Cl. (iii) MePoMe2 homogeneously distributed over perfusate, parenchyma and bile, consistent with unrestricted permeability. Other Po were transported transcellularly and excreted in bile. CrP was virtually excluded from the bile, attesting to a minimal role for 'bulk-phase pinocytotic' transcellular transport, or for 'paracellular' leakage. In summary, charged Po can be used as extracellular markers in liver, provided experimental conditions are adjusted to minimize their internalization. Some Po (e.g. PhePo) can reach intracellular concentrations which suffice for the compound to act as a reporter molecule of the cytosolic pH.
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Affiliation(s)
- K Bruynseels
- Department of Radiology, Faculteit Geneeskunde, Katholieke Universiteit Leuven, Belgium
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Bourdel-Marchasson I, Biran M, Thiaudière E, Delalande C, Decamps A, Manciet G, Canioni P. 31P magnetic resonance spectroscopy of human liver in elderly patients: changes according to nutritional status and inflammatory state. Metabolism 1996; 45:1059-61. [PMID: 8781290 DOI: 10.1016/s0026-0495(96)90002-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Magnetic resonance spectroscopy (MRS) was used to determine the phosphorylated metabolite content in the liver of elderly patients in various nutritional states: normal, with protein deprivation, and with acute inflammatory syndrome. 31P-MRS investigations were performed at 1.5 T, and localized liver spectra were recorded using a two-dimensional chemical shift imaging sequence. Comparison to control spectra recorded on 10 healthy volunteers (age, 30.5 +/- 2.1 years) showed that the aging process does not significantly modify 31P-MRS liver spectra. Patients with protein deprivation exhibited a higher value than controls for the phosphomonoesters/nucleoside triphosphates (PME/NTP) ratio (P < .05). This increase was not due to the decrease of NTP, since the ratio of inorganic phosphate to NTP (Pi/NTP) remained constant. A decrease in the phosphodiesters to NTP (PDE/NTP) ratio (P < .04) contributed to the observed increase in the PME/PDE ratio (P < .01). In contrast, no significant difference in 31P-MRS spectra was found between elderly patients with hypoalbuminemia associated with inflammatory syndrome and the control group. We conclude that elderly patients with protein deprivation displayed changes in the level of phosphorylated metabolites in the liver that were not observed in the case of inflammatory syndrome despite lower serum albumin (Alb) concentrations.
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Li CW, Negendank WG, Murphy-Boesch J, Padavic-Shaller K, Brown TR. Molar quantitation of hepatic metabolites in vivo in proton-decoupled, nuclear Overhauser effect enhanced 31P NMR spectra localized by three-dimensional chemical shift imaging. NMR IN BIOMEDICINE 1996; 9:141-155. [PMID: 9015801 DOI: 10.1002/(sici)1099-1492(199606)9:4<141::aid-nbm403>3.0.co;2-p] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Proton decoupling and nuclear Overhauser effect (NOE) enhancement significantly improve the signal-to-noise ratio and enhance resolution of metabolites in in vivo 31P MRS. We obtained proton-decoupled, NOE-enhanced, phospholipid-saturated 31P spectra localized to defined regions within the normal liver using three-dimensional chemical shift imaging. Proton-decoupling resulted in the resolution of two major peaks in the phosphomonoester (PME) region, three peaks in the phosphodiester (PDE) region and a diphosphodiester peak. In order to obtain molar quantitation, we measured the NOE of all hepatic phosphorus resonances, and we corrected for saturation effects by measuring hepatic metabolite T1 using the variable nutation angle method with phase-cycled, B1-independent rotation, adiabatic pulses. After corrections for saturation effects, NOE enhancement, B1 variations and point spread effects, the following mean concentrations (mmol/l of liver) (+/-SD) were obtained: [PME1] = 1.2 +/- 0.4, [PME2 + 2,3-DPG] = 1.1 +/- 0.1, [Pi + 2,3-DPG] = 2.8 +/- 0.5, [GPEth] = 2.8 +/- 0.7, [GPChol] = 3.5 +/- 0.6 and [beta-NTP] = 3.8 +/- 0.3. T1 and NOE enhancement were strongly correlated (r = 90), and indicated that the fractional contribution of 1H-31P dipolar relaxation to total 31P relaxation is minimal for NTPs, moderate for PMEs and high for PDEs in liver. Proton-decoupling and NOE enhancement permit one to obtain more information about in vivo metabolism of liver than previously available and should enhance the utility of 31P MRS for the study of hepatic disorders.
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Affiliation(s)
- C W Li
- Department of Nuclear Magnetic Resonance and Medical Spectroscopy, Fox Chase Cancer Center, Philadelphia, PA 19111, USA
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Menon DK, Harris M, Sargentoni J, Taylor-Robinson SD, Cox IJ, Morgan MY. In vivo hepatic 31P magnetic resonance spectroscopy in chronic alcohol abusers. Gastroenterology 1995; 108:776-88. [PMID: 7875480 DOI: 10.1016/0016-5085(95)90451-4] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
BACKGROUND/AIMS In vivo hepatic 31P magnetic resonance spectroscopy (MRS) can provide information on hepatic energy metabolism, phospholipid substrates, and hepatocyte lipid bilayers. The aim of this study was to ascertain the effects of alcohol ingestion on hepatic 31P spectral variables. METHODS Twenty-six chronic alcohol abusers underwent hepatic 31P MRS 6-12 hours after their last alcoholic drink; studies were repeated in 17 individuals following abstinence from alcohol. The reference population comprised 16 healthy volunteers. Ratios of phosphomonoesters (PME), inorganic phosphate, and phosphodiesters (PDE) relative to beta-adenosine triphosphate (ATP) were measured. RESULTS In patients with minimal liver injury, recent drinking was associated with a significant elevation in the mean PDE/ATP ratio (P < 0.0001) and an increase in mean PME/ATP, which was not significant; abstinence was associated with reductions in both metabolite ratios. In patients with alcoholic cirrhosis, recent drinking was associated with an elevation in mean PME/ATP (P < 0.05) and an increase in mean PDE/ATP, which was not significant; abstinence was associated with no significant change in PME/ATP but with a reduction in PDE/ATP. CONCLUSIONS In the absence of significant liver injury, chronic alcohol abuse is associated with the elevation of PME/ATP, possibly reflecting changes in hepatic redox potential, and of PDE/ATP, most likely reflecting the induction of hepatocyte endoplasmic reticulum. In the presence of cirrhosis, these changes are attenuated and modified.
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Affiliation(s)
- D K Menon
- NMR Unit, Royal Postgraduate Medical School, Hammersmith Hospital, London, England
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Affiliation(s)
- R A Kauppinen
- Department of Biochemistry and Biotechnology, A.I. Virtanen Institute, University of Kuopio, Finland
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McNamara R, Arias-Mendoza F, Brown TR. Investigation of broad resonances in 31P NMR spectra of the human brain in vivo. NMR IN BIOMEDICINE 1994; 7:237-242. [PMID: 7848814 DOI: 10.1002/nbm.1940070507] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Broad resonances that lie underneath the familiar small molecule profile of in vivo 31P NMR spectra can make accurate spectral integration of these mobile phosphates difficult. The two major broad components are the phosphate contained in the hydroxyapatite in cranial bone and the phosphodiester moiety in partially mobile membrane phospholipids. They can be removed with post-acquisition processing but this results in distortion of lineshapes and intensities and interferes with accurate quantitation. We have employed an off-resonance saturation procedure to eliminate the bone resonance and isolate the signal from the membrane phospholipids by subtraction. Selective saturation of the phospholipid resonance increases the clarity of the sharp peaks downfield from the phosphocreatine peak. Selective saturation 3-D chemical shift imaging techniques were used to create a localized phospholipid profile of the entire brain simultaneously. Monitoring localized phospholipid concentration may be important in studying demyelinating diseases.
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Affiliation(s)
- R McNamara
- Department of NMR and Medical Spectroscopy, Fox Chase Cancer Center, Philadelphia, PA 19111
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