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Zahr NM, Alt C, Mayer D, Rohlfing T, Manning-Bog A, Luong R, Sullivan EV, Pfefferbaum A. Associations between in vivo neuroimaging and postmortem brain cytokine markers in a rodent model of Wernicke's encephalopathy. Exp Neurol 2014; 261:109-19. [PMID: 24973622 PMCID: PMC4194214 DOI: 10.1016/j.expneurol.2014.06.015] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Revised: 06/13/2014] [Accepted: 06/17/2014] [Indexed: 02/03/2023]
Abstract
Thiamine (vitamin B1) deficiency, associated with a variety of conditions, including chronic alcoholism and bariatric surgery for morbid obesity, can result in the neurological disorder Wernicke's encephalopathy (WE). Recent work building upon early observations in animal models of thiamine deficiency has demonstrated an inflammatory component to the neuropathology observed in thiamine deficiency. The present, multilevel study including in vivo magnetic resonance imaging (MRI) and spectroscopy (MRS) and postmortem quantification of chemokine and cytokine proteins sought to determine whether a combination of these in vivo neuroimaging tools could be used to characterize an in vivo MR signature for neuroinflammation. Thiamine deficiency for 12days was used to model neuroinflammation; glucose loading in thiamine deficiency was used to accelerate neurodegeneration. Among 38 animals with regional brain tissue assayed postmortem for cytokine/chemokine protein levels, three groups of rats (controls+glucose, n=6; pyrithiamine+saline, n=5; pyrithiamine+glucose, n=13) underwent MRI/MRS at baseline (time 1), after 12days of treatment (time 2), and 3h after challenge (glucose or saline, time 3). In the thalamus of glucose-challenged, thiamine deficient animals, correlations between in vivo measures of pathology (lower levels of N-acetyle aspartate and higher levels of lactate) and postmortem levels of monocyte chemotactic protein-1 (MCP-1, also known as chemokine ligand 2, CCL2) support a role for this chemokine in thiamine deficiency-related neurodegeneration, but do not provide a unique in vivo signature for neuroinflammation.
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Affiliation(s)
- Natalie M Zahr
- Psychiatry & Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305, USA; Neuroscience Program, SRI International, Menlo Park, CA 94025, USA.
| | - Carsten Alt
- Immunology Program, SRI International, Menlo Park, CA 94025, USA; Palo Alto Institute for Research and Education, Palo Alto, CA 94304, USA
| | - Dirk Mayer
- Psychiatry & Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305, USA; Diagnostic Radiology and Nuclear Medicine, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA
| | - Torsten Rohlfing
- Neuroscience Program, SRI International, Menlo Park, CA 94025, USA
| | - Amy Manning-Bog
- Neuroscience Program, SRI International, Menlo Park, CA 94025, USA
| | - Richard Luong
- Department of Comparative Medicine, Stanford University School of Medicine, 300 Pasteur Drive, Edwards R321, Stanford, CA 94305, USA
| | - Edith V Sullivan
- Psychiatry & Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305, USA
| | - Adolf Pfefferbaum
- Psychiatry & Behavioral Sciences, Stanford University School of Medicine, 401 Quarry Rd., Stanford, CA 94305, USA; Neuroscience Program, SRI International, Menlo Park, CA 94025, USA
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Griffin JL, Salek RM. Metabolomic applications to neuroscience: more challenges than chances? Expert Rev Proteomics 2014; 4:435-7. [PMID: 17705699 DOI: 10.1586/14789450.4.4.435] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Julian L Griffin
- University of Cambridge, Department of Biochemistry, Cambridge, UK.
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3
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Gu M, Zahr NM, Spielman DM, Sullivan EV, Pfefferbaum A, Mayer D. Quantification of glutamate and glutamine using constant-time point-resolved spectroscopy at 3 T. NMR IN BIOMEDICINE 2013; 26:164-72. [PMID: 22761057 PMCID: PMC3742105 DOI: 10.1002/nbm.2831] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 05/30/2012] [Accepted: 05/30/2012] [Indexed: 05/30/2023]
Abstract
Separate quantification of glutamate (Glu) and glutamine (Gln) using conventional MRS on clinical scanners is challenging. In previous work, constant-time point-resolved spectroscopy (CT-PRESS) was optimized at 3 T to detect Glu, but did not resolve Gln. To quantify Glu and Gln, a time-domain basis set was constructed taking into account metabolite T(2) relaxation times and dephasing from B(0) inhomogeneity. Metabolite concentrations were estimated by fitting the basis one-dimensional CT-PRESS diagonal magnitude spectra to the measured spectrum. This method was first validated using seven custom-built phantoms containing variable metabolite concentrations, and then applied to in vivo data acquired in rats exposed to vaporized ethanol and controls. Separate metabolite quantification revealed increased Gln after 16 weeks and increased Glu after 24 weeks of vaporized ethanol exposure in ethanol-treated compared with control rats. Without separate quantification, the signal from the combined resonances of Glu and Gln (Glx) showed an increase at both 16 and 24 weeks in ethanol-exposed rats, precluding the determination of the independent and differential contribution of each metabolite at each time.
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Affiliation(s)
- Meng Gu
- Department of Radiology, Stanford University, Stanford, CA 94305, USA.
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4
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Opstad KS, Bell BA, Griffiths JR, Howe FA. An assessment of the effects of sample ischaemia and spinning time on the metabolic profile of brain tumour biopsy specimens as determined by high-resolution magic angle spinning (1)H NMR. NMR IN BIOMEDICINE 2008; 21:1138-47. [PMID: 18666093 DOI: 10.1002/nbm.1296] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
High-resolution magic angle spinning (HRMAS) (1)H NMR of biopsy tissue provides a biochemical profile that has potential diagnostic and prognostic value, and can aid interpretation of the lower-resolution (1)H-NMR spectra obtained in vivo. However, the biochemical profile obtained may be affected by experimental factors such as a period of ischaemia before snap-freezing of the biopsy tissue for subsequent analysis and the mechanical stress of the spinning procedure of HRMAS itself. We have used normal rat brain cortex as a 'gold standard', either funnel-frozen or deliberately allowed to become ischaemic for set periods of time before snap-freezing, to quantitatively investigate these two effects. In addition, we have compared biochemical changes that occur in normal rat brain during HRMAS (spun continuously at 5 kHz for 4 h at 4 degrees C as could be required for a two-dimensional acquisition) with those that occur in biopsy samples from low-grade and high-grade adult human astrocytomas, during the same HRMAS procedure. Significant changes due to delayed initial sample freezing were noted in metabolites associated with glycolysis (alanine, glucose and lactate), as expected. However, for the funnel-frozen rat tissue at 4 degrees C, there were even more significant changes, which appear to be the result of extended spinning at 5 kHz. In particular, the 18% total creatine increase observed is unlikely to be de novo synthesis of creatine. More likely, the asymptotic exponential increase in creatine suggests an exponential release of an NMR-invisible bound creatine store as a result of tissue damage from mechanical stress of sample spinning. Overall, it appears that tissue ischaemia during biopsy excision and delays in snap-freezing may have less significant effects on metabolite profile than the prolonged spinning times required for two-dimensional HRMAS, and this must be accounted for when results are being interpreted.
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Affiliation(s)
- Kirstie S Opstad
- Division of Basic Medical Sciences, St George's, University of London, UK.
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Iltis I, Marjańska M, Du F, Koski DM, Zhu XH, Ugurbil K, Chen W, Henry PG. (1)H MRS in the rat brain under pentobarbital anesthesia: accurate quantification of in vivo spectra in the presence of propylene glycol. Magn Reson Med 2008; 59:631-5. [PMID: 18224694 DOI: 10.1002/mrm.21502] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Commercial solutions for pentobarbital anesthesia typically contain water H spectra. The purpose of the present study was to measure the concentration of metabolites in the rat brain in vivo under pentobarbital anesthesia using 1H MRS. Resonances of PG, but not ethanol, were observed in the rat brain. Chemical shifts and J-coupling constants for PG were measured at 37 degrees C and pH 7.1 and used for spectral simulation. Inclusion of the simulated PG spectrum in the basis set for LCModel analysis enabled accurate fitting of in vivo spectra. This work demonstrates that concentration of brain metabolites can be reliably measured using 1H spectroscopy under pentobarbital anesthesia. The chemical shifts and J-coupling values reported here can be used to simulate the spectrum of PG at any field strength, with various pulse sequences.
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Affiliation(s)
- Isabelle Iltis
- Center for Magnetic Resonance Research and Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455, USA.
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Scheurer E, Ith M, Dietrich D, Kreis R, Hüsler J, Dirnhofer R, Boesch C. Statistical evaluation of time-dependent metabolite concentrations: estimation of post-mortem intervals based on in situ 1H-MRS of the brain. NMR IN BIOMEDICINE 2005; 18:163-172. [PMID: 15578674 DOI: 10.1002/nbm.934] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Knowledge of the time interval from death (post-mortem interval, PMI) has an enormous legal, criminological and psychological impact. Aiming to find an objective method for the determination of PMIs in forensic medicine, 1H-MR spectroscopy (1H-MRS) was used in a sheep head model to follow changes in brain metabolite concentrations after death. Following the characterization of newly observed metabolites (Ith et al., Magn. Reson. Med. 2002; 5: 915-920), the full set of acquired spectra was analyzed statistically to provide a quantitative estimation of PMIs with their respective confidence limits. In a first step, analytical mathematical functions are proposed to describe the time courses of 10 metabolites in the decomposing brain up to 3 weeks post-mortem. Subsequently, the inverted functions are used to predict PMIs based on the measured metabolite concentrations. Individual PMIs calculated from five different metabolites are then pooled, being weighted by their inverse variances. The predicted PMIs from all individual examinations in the sheep model are compared with known true times. In addition, four human cases with forensically estimated PMIs are compared with predictions based on single in situ MRS measurements. Interpretation of the individual sheep examinations gave a good correlation up to 250 h post-mortem, demonstrating that the predicted PMIs are consistent with the data used to generate the model. Comparison of the estimated PMIs with the forensically determined PMIs in the four human cases shows an adequate correlation. Current PMI estimations based on forensic methods typically suffer from uncertainties in the order of days to weeks without mathematically defined confidence information. In turn, a single 1H-MRS measurement of brain tissue in situ results in PMIs with defined and favorable confidence intervals in the range of hours, thus offering a quantitative and objective method for the determination of PMIs.
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Affiliation(s)
- Eva Scheurer
- Institute of Forensic Medicine, University of Bern, Bern, Switzerland
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Schwarcz A, Natt O, Watanabe T, Boretius S, Frahm J, Michaelis T. Localized proton MRS of cerebral metabolite profiles in different mouse strains. Magn Reson Med 2003; 49:822-7. [PMID: 12704764 DOI: 10.1002/mrm.10445] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Localized proton MR spectroscopy (MRS) was used to quantify cerebral metabolite concentrations in NMRI (n = 8), BALB/c (n = 7), and C57BL/6 (n = 8) mice in vivo and 1 hr after global irreversible ischemia (2.35 T, STEAM, TR/TE/TM = 6000/20/10 ms, 4 x 3 x 4 mm(3) volume, corrections for cerebrospinal fluid). Anatomical MRI and proton MRS revealed significant differences of the C57BL/6 strain in comparison with both BALB/c and NMRI mice. While MRI volumetry yielded larger ventricular spaces of the C57BL/6 strain, proton MRS resulted in elevated concentrations of N-acetylaspartate (tNAA), creatine and phosphocreatine (tCr), choline-containing compounds (Cho), glucose (Glc), and lactate (Lac) relative to BALB/c mice and elevated Glc relative to NMRI mice. Apart from the expected decrease of Glc and increase of Lac 1 hr post mortem, C57BL/6 mice presented with significant reductions of tNAA, tCr, and Cho, whereas these metabolites remained unchanged in BALB/c and NMRI mice. The results support the hypothesis that the more pronounced vulnerability of C57BL/6 mice to brain ischemia is linked to strain-dependent differences of the cerebral energy metabolism.
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Affiliation(s)
- Attila Schwarcz
- Biomedizinische NMR Forschungs GmbH am Max-Planck-Institut für biophysikalische Chemie, Göttingen, Germany
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Battistuta J, Bjartmar C, Trapp BD. Postmortem degradation of N-acetyl aspartate and N-acetyl aspartylglutamate: an HPLC analysis of different rat CNS regions. Neurochem Res 2001; 26:695-702. [PMID: 11519729 DOI: 10.1023/a:1010947605921] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
N-acetyl aspartate (NAA), a putative marker of neuronal injury, can be measured non-invasively in patients by magnetic resonance spectroscopy (MRS). Interpretation of in vivo MRS data, however, requires neuropathological correlates to NAA alterations using autopsy or biopsy material. Since detailed hydrolysis data is lacking, NAA and the related dipeptide N-acetyl aspartylglutamate (NAAG) were quantified by high performance liquid chromatography (HPLC) in different rat CNS regions over 24 h postmortem. Both molecules decreased rapidly 1-4 h postmortem, and subsequently slower with time. The average reduction at 24 h was 46% and 38% for NAA and NAAG respectively. The NAA reduction was proportionally smaller in cortical areas (34-37%) compared to more caudal regions (54-58%). An exception was the optic nerve, a pure white matter tract, where NAA and NAAG hydrolysis was slower. The NAA/NAAG ratio remained relatively constant, but exhibited marked regional differences. The data show a significant postmortem degradation of NAA and NAAG that needs to be considered when these compounds are studied ex-vivo.
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Affiliation(s)
- J Battistuta
- Department of Chemistry, Cleveland State University, Ohio, USA
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Abstract
Localized in vivo proton magnetic resonance spectroscopy at 4.7 T was used to examine the brains of rats that were given the antipsychotic drugs haloperidol, clozapine, or olanzapine for 1 week. Spectra were collected before and during treatment. The ratios of N-acetylaspartate (NAA) to creatine (Cr) and choline to Cr were determined from the spectra. No significant differences in these ratios were seen among the rats given the various antipsychotic medications or between the control rats and the treated rats. No significant time-dependent changes were seen in most cases, except for a small reduction of NAA/Cr after 7 days of olanzapine administration. These results suggest that differences in brain metabolite ratios in vivo in schizophrenics relative to controls, at least for short-term treatment, arise from the disease, and not as a metabolic effect of the medication.
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Affiliation(s)
- D M Lindquist
- Department of Applied Science, University of Arkansas at Little Rock, USA
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10
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Dreher W, Leibfritz D. Improved proton spectroscopic U-FLARE imaging for the detection of coupled resonances in the rat brain in vivo. Magn Reson Imaging 1999; 17:611-21. [PMID: 10231188 DOI: 10.1016/s0730-725x(98)00198-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Modifications of the pulse sequence for spectroscopic U-FLARE imaging are discussed to detect not only the predominant singlet signals of N-acetylaspartate, total creatine, and choline containing compounds or the doublet signal of lactate, but also the coupled resonances of glutamate, glutamine, taurine and myo-inositol. Effective homonuclear decoupling is achieved by use of constant time chemical shift encoding. A maximum signal-to-noise ratio (SNR) can be obtained for a certain coupled resonance of interest by optimizing the evolution period t(c) of the J modulated spin echo. Good reproducibility and a high SNR were achieved by combining several methods for water suppression and by using the displaced variant of U-FLARE. Measurements of a 3 mm slice of the rat brain were performed in vivo within 4 min, giving a nominal voxel size of 1.5 x 1.5 x 3.0 mm3 or 1.5 x 0.75 x 3.0 mm3. Thus, optimized spectroscopic U-FLARE is a powerful tool for proton spectroscopic imaging with high spectral, spatial and temporal resolution.
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Affiliation(s)
- W Dreher
- Universität Bremen, Fachbereich 2 (Biologie/Chemie), Bremen, Germany.
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Dijkhuizen RM, de Graaf RA, Garwood M, Tulleken KA, Nicolay K. Spatial assessment of the dynamics of lactate formation in focal ischemic rat brain. J Cereb Blood Flow Metab 1999; 19:376-9. [PMID: 10197507 DOI: 10.1097/00004647-199904000-00003] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Early identification of the potentially salvageable penumbra is critical for the determination of therapeutic intervention strategies in acute focal cerebral ischemia. This study differentiates the ischemic penumbra from the core on the basis of the dynamics of lactate formation. This was tested in a rat model of focal cerebral ischemia by infusion of [1-13C]-glucose, using lactate-edited magnetic resonance spectroscopic imaging techniques. The authors detected essentially no enrichment of lactate with 13C-label from the infused 13C-glucose in the ischemic core. However, in borderzone areas, 13C was incorporated into lactate, which could point toward compromised but potentially viable tissue. The authors' findings suggest that this combination of 13C-glucose infusion with the proposed magnetic resonance methods may aid in differentiating the penumbra from the core in cerebral ischemia.
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Affiliation(s)
- R M Dijkhuizen
- Department of Neurosurgery, University Hospital Utrecht, The Netherlands
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Dreher W, Kühn B, Gyngell ML, Busch E, Niendorf T, Hossmann KA, Leibfritz D. Temporal and regional changes during focal ischemia in rat brain studied by proton spectroscopic imaging and quantitative diffusion NMR imaging. Magn Reson Med 1998; 39:878-88. [PMID: 9621911 DOI: 10.1002/mrm.1910390605] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The early development of focal ischemia after permanent occlusion of the right middle cerebral artery (MCA) was studied in six rats using interleaved measurements by diffusion-weighted NMR imaging (DWI) of water and two variants of proton spectroscopic imaging (SI), multiecho SI (TE: 136, 272, 408 ms) and short TE SI (TE: 20 ms). Measurements on a 4.7-T NMR imaging system were performed between the control phase and approximately 6 h postocclusion. In the center of the ischemic lesion of all rats, the apparent diffusion coefficient (ADC) decreased rapidly to 84.4 +/- 4.2% (mean +/- SD) of the control values approximately 2 min postocclusion. Approximately 6 h postocclusion, the ADC was reduced to 67.1 +/- 5.9%. In contrast, large differences between the animals were observed for the temporal increase of lactate (Lac) in the ipsilateral hemisphere. The maximum Lac signal was reached in four rats after 0.5-1.5 h, and in two rats was not reached even after 6 h postocclusion. Six h postocclusion, SI spectra measured at a TE of 136 ms revealed a decrease in the CH3 signal of N-acetylaspartate (NAA) to 67 +/- 13% of the control values. Differences were observed between the spatial regions of decreased NAA and increased Lac. In the lesions, a T2 relaxation time of Lac of 292 +/- 40 ms, considering a J-coupling constant of 6.9 Hz, was measured. Furthermore, a prolongation of the T2 of the CH3 signal of creatine/phosphocreatine (Cr/PCr) was observed in the lesion, from 163 +/- 22 ms during control to 211 +/- 41 ms approximately 6 h postocclusion. The experiments proved that DWI and proton SI are valuable tools to provide complementary information on processes associated with brain infarcts.
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van der Toorn A, Syková E, Dijkhuizen RM, Vorísek I, Vargová L, Skobisová E, van Lookeren Campagne M, Reese T, Nicolay K. Dynamic changes in water ADC, energy metabolism, extracellular space volume, and tortuosity in neonatal rat brain during global ischemia. Magn Reson Med 1996; 36:52-60. [PMID: 8795020 DOI: 10.1002/mrm.1910360110] [Citation(s) in RCA: 211] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
To obtain a better understanding of the mechanisms underlying early changes in the brain water apparent diffusion coefficient (ADC) observed in cerebral ischemia, dynamic changes in the ADC of water and in the energy status were measured at postnatal day 8 or 9 in neonatal rat brains after cardiac arrest using 1H MRS/MRI and 31P MRS, respectively. The time courses of the MR parameters were compared with changes in the extracellular space (ECS) volume fraction (alpha) and tortuosity (lambda), determined from concentration-time profiles of tetramethylammonium applied by iontophoresis. The data show a decrease of the ADC of tissue water after induction of global ischemia of which the time course strongly correlates with the time course of the decrease in the ECS volume fraction and the increase in ECS tortuosity. This indicates that cell swelling is an important cause for the ADC decrease of water.
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Affiliation(s)
- A van der Toorn
- Department of in vivo NMR, Bijvoet Center for Biomolecular Research, Utrecht University, The Netherlands
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14
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Higuchi T, Fernandez EJ, Maudsley AA, Shimizu H, Weiner MW, Weinstein PR. Mapping of lactate and N-acetyl-L-aspartate predicts infarction during acute focal ischemia: in vivo 1H magnetic resonance spectroscopy in rats. Neurosurgery 1996; 38:121-9; discussion 129-30. [PMID: 8747960 DOI: 10.1097/00006123-199601000-00030] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The time course, anatomic distribution, and extent of changes in cerebral lactate, N-acetyl-L-aspartate (NAA), and other metabolite levels determined by three-dimensional in vivo 1H magnetic resonance spectroscopy and single-voxel spectral analysis after middle cerebral artery occlusion in rats. Increased lactate was detected in the central ischemic region within 1.3 hours after the onset of permanent occlusion (n = 22) or 0.5 hour after the onset of 1 hour of temporary occlusion and then reperfusion (n = 8). Permanent occlusion resulted in persistent lactate elevation and a 25.4 +/- 4.1% reduction in the NAA peak after 1.3 hours; NAA was almost completely depleted after 24 hours. Results also demonstrated delayed depletion of all other magnetic resonance spectroscopy-visible 1H metabolites, including creatine, choline, and glutamate, after permanent occlusion. After 1 hour of temporary focal ischemia, lactate returned to nearly normal levels within 0.4 hour after the onset of reperfusion; at 72 hours, a recurrent increase in lactate and a new decrease in NAA were observed, suggesting delayed tissue injury. Histological analysis, performed in 10 rats, demonstrated infarcts that corresponded in distribution to regions of NAA depletion at 72 hours. These findings indicate that lactate elevation is a sensitive early marker of ischemia; however, temporary recovery of lactate accumulation after reperfusion did not predict sustained metabolic recovery. In contrast, NAA depletion within 1.3 hours after the onset of ischemia identified central ischemic regions that were destined for infarction. Potential clinical applications include selection and monitoring of therapeutic intervention, as well as prediction of outcome, in patients with acute stroke.
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Affiliation(s)
- T Higuchi
- Magnetic Resonance Unit, Department of Veterans Affairs Medical Center, San Francisco, California, USA
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15
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Gyngell ML, Busch E, Schmitz B, Kohno K, Back T, Hoehn-Berlage M, Hossmann KA. Evolution of acute focal cerebral ischaemia in rats observed by localized 1H MRS, diffusion-weighted MRI, and electrophysiological monitoring. NMR IN BIOMEDICINE 1995; 8:206-214. [PMID: 8664106 DOI: 10.1002/nbm.1940080505] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Focal cerebral ischaemia was produced in 11 rats by permanent occlusion of the right middle cerebral artery (MCA) using a suture model modified to enable manipulation with the animals in situ in an NMR spectrometer. The development of the ischaemic insults and the resultant infarcts were observed for up to 6 h by localized 1H MRS and diffusion-weighted MRI while performing continuous monitoring of electroencephalogram and extracellular DC potential. The ischaemic areas were depicted as regions of hyperintensity in the diffusion-weighted images. Signals due to lactate became visible in the 1H spectra after MCA occlusion indicating the onset of anaerobic glycolysis. A depletion of N-acetylaspartate was seen in all animals post-occlusion. Transient or stepwise increases of lactate were observed to occur coincidentally with the events of spontaneous transient peri-infarct depolarization detected by the electrophysiological measurements. Expansion of the ischaemic area delineated in the diffusion-weighted images also accompanied peri-infarct depolarizations. These observations are consistent with transient peri-infarct depolarization playing a role in the growth of infarcts.
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Affiliation(s)
- M L Gyngell
- Max-Planck-Institut für neurologische Forschung, Abteilung für experimentelle Neurologie, Köln, Federal Republic of Germany
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