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Huang J, Chen Z, van Zijl PCM, Law LH, Pemmasani Prabakaran RS, Park SW, Xu J, Chan KWY. Effect of inhaled oxygen level on dynamic glucose-enhanced MRI in mouse brain. Magn Reson Med 2024; 92:57-68. [PMID: 38308151 PMCID: PMC11055662 DOI: 10.1002/mrm.30035] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 12/23/2023] [Accepted: 01/15/2024] [Indexed: 02/04/2024]
Abstract
PURPOSE To investigate the effect of inhaled oxygen level on dynamic glucose enhanced (DGE) MRI in mouse brain tissue and CSF at 3 T. METHODS DGE data of brain tissue and CSF from mice under normoxia or hyperoxia were acquired in independent and interleaved experiments using on-resonance variable delay multi-pulse (onVDMP) MRI. A bolus of 0.15 mL filtered 50% D-glucose was injected through the tail vein over 1 min during DGE acquisition. MRS was acquired before and after DGE experiments to confirm the presence of D-glucose. RESULTS A significantly higher DGE effect under normoxia than under hyperoxia was observed in brain tissue (p = 0.0001 and p = 0.0002 for independent and interleaved experiments, respectively), but not in CSF (p > 0.3). This difference is attributed to the increased baseline MR tissue signal under hyperoxia induced by a shortened T1 and an increased BOLD effect. When switching from hyperoxia to normoxia without glucose injection, a signal change of ˜3.0% was found in brain tissue and a signal change of ˜1.5% was found in CSF. CONCLUSIONS DGE signal was significantly lower under hyperoxia than that under normoxia in brain tissue, but not in CSF. The reason is that DGE effect size of brain tissue is affected by the baseline signal, which could be influenced by T1 change and BOLD effect. Therefore, DGE experiments in which the oxygenation level is changed from baseline need to be interpreted carefully.
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Affiliation(s)
- Jianpan Huang
- Department of Diagnostic Radiology, The University of Hong Kong, Hong Kong, China
| | - Zilin Chen
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
| | - Peter CM van Zijl
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lok Hin Law
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
| | - Rohith Saai Pemmasani Prabakaran
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
- Hong Kong Centre for Cerebro-Cardiovascular Health Engineering (COCHE), Hong Kong, China
| | - Se Weon Park
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
- Hong Kong Centre for Cerebro-Cardiovascular Health Engineering (COCHE), Hong Kong, China
| | - Jiadi Xu
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Kannie WY Chan
- Department of Biomedical Engineering, City University of Hong Kong, Hong Kong, China
- Russell H. Morgan Department of Radiology and Radiological Science, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Hong Kong Centre for Cerebro-Cardiovascular Health Engineering (COCHE), Hong Kong, China
- City University of Hong Kong Shenzhen Research Institute, Shenzhen, China
- Tung Biomedical Science Centre, City University of Hong Kong, Hong Kong, China
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Xu W, Borges K. Case for supporting astrocyte energetics in glucose transporter 1 deficiency syndrome. Epilepsia 2024. [PMID: 38767952 DOI: 10.1111/epi.18013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2024] [Revised: 04/30/2024] [Accepted: 05/02/2024] [Indexed: 05/22/2024]
Abstract
In glucose transporter 1 deficiency syndrome (Glut1DS), glucose transport into brain is reduced due to impaired Glut1 function in endothelial cells at the blood-brain barrier. This can lead to shortages of glucose in brain and is thought to contribute to seizures. Ketogenic diets are the first-line treatment and, among many beneficial effects, provide auxiliary fuel in the form of ketone bodies that are largely metabolized by neurons. However, Glut1 is also the main glucose transporter in astrocytes. Here, we review data indicating that glucose shortage may also impact astrocytes in addition to neurons and discuss the expected negative biochemical consequences of compromised astrocytic glucose transport for neurons. Based on these effects, auxiliary fuels are needed for both cell types and adding medium chain triglycerides (MCTs) to ketogenic diets is a biochemically superior treatment for Glut1DS compared to classical ketogenic diets. MCTs provide medium chain fatty acids (MCFAs), which are largely metabolized by astrocytes and not neurons. MCFAs supply energy and contribute carbons for glutamine and γ-aminobutyric acid synthesis, and decanoic acid can also block α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid glutamate receptors. MCTs do not compete with metabolism of ketone bodies mostly occurring in neurons. Triheptanoin, an anaplerotic but also gluconeogenic uneven MCT, may be another potential addition to ketogenic diets, although maintenance of "ketosis" can be difficult. Gene therapy has also targeted both endothelial cells and astrocytes. Other approaches to increase fuel delivery to the brain currently investigated include exchange of Glut1DS erythrocytes with healthy cells, infusion of lactate, and pharmacological improvement of glucose transport. In conclusion, although it remains difficult to assess impaired astrocytic energy metabolism in vivo, astrocytic energy needs are most likely not met by ketogenic diets in Glut1DS. Thus, we propose prospective studies including monitoring of blood MCFA levels to find optimal doses for add-on MCT to ketogenic diets and assessing of short- and long-term outcomes.
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Affiliation(s)
- Weizhi Xu
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland, Australia
| | - Karin Borges
- School of Biomedical Sciences, University of Queensland, St Lucia, Queensland, Australia
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3
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Gunawan F, Matson BC, Coppoli A, Jiang L, Ding Y, Perry R, Sanchez-Rangel E, DeAguiar RB, Behar KL, Rothman DL, Mason GF, Hwang JJ. Deficits in brain glucose transport among younger adults with obesity. Obesity (Silver Spring) 2024. [PMID: 38764181 DOI: 10.1002/oby.24034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2023] [Revised: 03/05/2024] [Accepted: 03/13/2024] [Indexed: 05/21/2024]
Abstract
OBJECTIVE Obesity is associated with alterations in eating behavior and neurocognitive function. In this study, we investigate the effect of obesity on brain energy utilization, including brain glucose transport and metabolism. METHODS A total of 11 lean participants and 7 young healthy participants with obesity (mean age, 27 years) underwent magnetic resonance spectroscopy scanning coupled with a hyperglycemic clamp (target, ~180 mg/dL) using [1-13C] glucose to measure brain glucose uptake and metabolism, as well as peripheral markers of insulin resistance. RESULTS Individuals with obesity demonstrated an ~20% lower ratio of brain glucose uptake to cerebral glucose metabolic rate (Tmax/CMRglucose) than lean participants (2.12 ± 0.51 vs. 2.67 ± 0.51; p = 0.04). The cerebral tricarboxylic acid cycle flux (VTCA) was similar between the two groups (p = 0.64). There was a negative correlation between total nonesterified fatty acids and Tmax/CMRglucose (r = -0.477; p = 0.045). CONCLUSIONS We conclude that CMRglucose is unlikely to differ between groups due to similar VTCA, and, therefore, the glucose transport Tmax is lower in individuals with obesity. These human findings suggest that obesity is associated with reduced cerebral glucose transport capacity even at a young age and in the absence of other cardiometabolic comorbidities, which may have implications for long-term brain function and health.
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Affiliation(s)
- Felona Gunawan
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Brooke C Matson
- Division of Endocrinology and Metabolism, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
| | - Anastasia Coppoli
- Yale Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Lihong Jiang
- Yale Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Yuyan Ding
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Rachel Perry
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Elizabeth Sanchez-Rangel
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Renata Belfort DeAguiar
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Kevin L Behar
- Yale Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
- Department of Psychiatry, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
| | - Douglas L Rothman
- Yale Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Graeme F Mason
- Yale Magnetic Resonance Research Center, Department of Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
- Department of Psychiatry, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Yale University, New Haven, Connecticut, USA
| | - Janice J Hwang
- Section of Endocrinology and Metabolism, Department of Internal Medicine, Yale School of Medicine, Yale University, New Haven, Connecticut, USA
- Division of Endocrinology and Metabolism, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, USA
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4
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Niess F, Strasser B, Hingerl L, Bader V, Frese S, Clarke WT, Duguid A, Niess E, Motyka S, Krššák M, Trattnig S, Scherer T, Lanzenberger R, Bogner W. Whole-brain deuterium metabolic imaging via concentric ring trajectory readout enables assessment of regional variations in neuronal glucose metabolism. Hum Brain Mapp 2024; 45:e26686. [PMID: 38647048 PMCID: PMC11034002 DOI: 10.1002/hbm.26686] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 03/13/2024] [Accepted: 04/04/2024] [Indexed: 04/25/2024] Open
Abstract
Deuterium metabolic imaging (DMI) is an emerging magnetic resonance technique, for non-invasive mapping of human brain glucose metabolism following oral or intravenous administration of deuterium-labeled glucose. Regional differences in glucose metabolism can be observed in various brain pathologies, such as Alzheimer's disease, cancer, epilepsy or schizophrenia, but the achievable spatial resolution of conventional phase-encoded DMI methods is limited due to prolonged acquisition times rendering submilliliter isotropic spatial resolution for dynamic whole brain DMI not feasible. The purpose of this study was to implement non-Cartesian spatial-spectral sampling schemes for whole-brain 2H FID-MR Spectroscopic Imaging to assess time-resolved metabolic maps with sufficient spatial resolution to reliably detect metabolic differences between healthy gray and white matter regions. Results were compared with lower-resolution DMI maps, conventionally acquired within the same session. Six healthy volunteers (4 m/2 f) were scanned for ~90 min after administration of 0.8 g/kg oral [6,6']-2H glucose. Time-resolved whole brain 2H FID-DMI maps of glucose (Glc) and glutamate + glutamine (Glx) were acquired with 0.75 and 2 mL isotropic spatial resolution using density-weighted concentric ring trajectory (CRT) and conventional phase encoding (PE) readout, respectively, at 7 T. To minimize the effect of decreased signal-to-noise ratios associated with smaller voxels, low-rank denoising of the spatiotemporal data was performed during reconstruction. Sixty-three minutes after oral tracer uptake three-dimensional (3D) CRT-DMI maps featured 19% higher (p = .006) deuterium-labeled Glc concentrations in GM (1.98 ± 0.43 mM) compared with WM (1.66 ± 0.36 mM) dominated regions, across all volunteers. Similarly, 48% higher (p = .01) 2H-Glx concentrations were observed in GM (2.21 ± 0.44 mM) compared with WM (1.49 ± 0.20 mM). Low-resolution PE-DMI maps acquired 70 min after tracer uptake featured smaller regional differences between GM- and WM-dominated areas for 2H-Glc concentrations with 2.00 ± 0.35 mM and 1.71 ± 0.31 mM, respectively (+16%; p = .045), while no regional differences were observed for 2H-Glx concentrations. In this study, we successfully implemented 3D FID-MRSI with fast CRT encoding for dynamic whole-brain DMI at 7 T with 2.5-fold increased spatial resolution compared with conventional whole-brain phase encoded (PE) DMI to visualize regional metabolic differences. The faster metabolic activity represented by 48% higher Glx concentrations was observed in GM- compared with WM-dominated regions, which could not be reproduced using whole-brain DMI with the low spatial resolution protocol. Improved assessment of regional pathologic alterations using a fully non-invasive imaging method is of high clinical relevance and could push DMI one step toward clinical applications.
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Affiliation(s)
- Fabian Niess
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Bernhard Strasser
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Lukas Hingerl
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Viola Bader
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Sabina Frese
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - William T. Clarke
- Wellcome Centre for Integrative Neuroimaging, FMRIB, Nuffield Department of Clinical NeurosciencesUniversity of OxfordOxfordUK
| | - Anna Duguid
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
| | - Eva Niess
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for MR Imaging Biomarkers (BIOMAK), Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Stanislav Motyka
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for MR Imaging Biomarkers (BIOMAK), Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
| | - Martin Krššák
- Department of Medicine III, Division of Endocrinology and MetabolismMedical University of ViennaViennaAustria
| | - Siegfried Trattnig
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
- Institute for Clinical Molecular MRIKarl Landsteiner SocietySt. PöltenAustria
| | - Thomas Scherer
- Department of Medicine III, Division of Endocrinology and MetabolismMedical University of ViennaViennaAustria
| | - Rupert Lanzenberger
- Department of Psychiatry and Psychotherapy, Comprehensive Center for Clinical Neurosciences and Mental Health (C3NMH)Medical University of ViennaViennaAustria
| | - Wolfgang Bogner
- High Field MR Center, Department of Biomedical Imaging and Image‐Guided TherapyMedical University of ViennaViennaAustria
- Christian Doppler Laboratory for MR Imaging Biomarkers (BIOMAK), Department of Biomedical Imaging and Image‐guided TherapyMedical University of ViennaViennaAustria
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5
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Kuribayashi H, Urushibata Y, Imai H, Ahn S, Seethamraju RT, Isa T, Okada T. Quantification of Cerebral Glucose Concentrations via Detection of the H1-α-Glucose Peak in 1 H MRS at 7 T. J Magn Reson Imaging 2024; 59:661-672. [PMID: 37259965 DOI: 10.1002/jmri.28834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Revised: 05/14/2023] [Accepted: 05/16/2023] [Indexed: 06/02/2023] Open
Abstract
BACKGROUND Sensitive detection and quantification of cerebral glucose is desired. PURPOSE To quantify cerebral glucose by detecting the H1-α-glucose peak at 5.23 ppm in 1 H magnetic resonance spectroscopy at 7 T. STUDY TYPE Prospective. SUBJECTS Twenty-eight non-fasted healthy subjects (aged 20-28 years). FIELD STRENGTH/SEQUENCE Short echo time stimulated echo acquisition mode (short-TE STEAM) and semi-localized by adiabatic selective refocusing (semi-LASER) at 7 T. ASSESSMENT Single voxel spectra were obtained from the posterior cingulate cortex (27-mL) using a 32-channel head coil. The H1-α-glucose peak in the spectrum with retrospective removal of the residual water peak was fitted using LCModel with a glucose basis set of only the H1-α-glucose peak. Conventional spectral analysis was performed with a glucose basis set of a full spectral pattern of glucose, also. Fitting precision was evaluated with Cramér-Rao lower bounds (CRLBs). The repeatability of glucose quantification via the semi-LASER sequence was tested. STATISTICAL TESTS Paired or Welch's t-test were used for normally distributed values. A P value of <0.05 was considered significant. The repeatability of measures was analyzed using coefficient of variation (CV). RESULTS Removal of the residual water peak improved the flatness and stability of baselines around the H1-α-glucose peak and reduced CRLBs for fitting the H1-α-glucose peak. The semi-LASER sequence was superior to the short-TE STEAM in the higher signal-to-noise ratio of the H1-α-glucose peak (mean ± SD 7.9 ± 2.5, P < 0.001). The conventional analysis overfitted the H1-α-glucose peak. The individual CVs of glucose quantification by detecting the H1-α-glucose peak were smaller than the corresponding CRLBs. DATA CONCLUSION Cerebral glucose concentration is quantitated to be 1.07 mM by detecting the H1-α-glucose peak in the semi-LASER spectra. Despite requiring long scan times, detecting the H1-α-glucose peak allows true glucose quantification free from the influence of overlapping taurine and macromolecule signals. EVIDENCE LEVEL 2 TECHNICAL EFFICACY STAGE: 1.
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Affiliation(s)
| | | | - Hirohiko Imai
- Kyoto University Graduate School of Informatics, Kyoto, Japan
| | - Sinyeob Ahn
- Siemens Medical Solutions, Berkeley, California, USA
| | | | - Tadashi Isa
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Tomohisa Okada
- Human Brain Research Center, Kyoto University Graduate School of Medicine, Kyoto, Japan
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6
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Labadie C, Möller HE. Editorial on "Quantification of Cerebral Glucose Concentrations via Detection of the H1-α-Glucose Peak in 1 H MRS at 7 T". J Magn Reson Imaging 2024; 59:673-674. [PMID: 37285054 DOI: 10.1002/jmri.28833] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2023] [Accepted: 05/09/2023] [Indexed: 06/08/2023] Open
Affiliation(s)
- Christian Labadie
- Methods and Development Group Nuclear Magnetic Resonance, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
| | - Harald E Möller
- Methods and Development Group Nuclear Magnetic Resonance, Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig, Germany
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7
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Tetarbe M, Wisnowski JL, Geyer E, Tamrazi B, Wood T, Mietzsch U, Blüml S, Wu TW. Cerebral Glucose Concentration in Neonatal Hypoxic-Ischemic Encephalopathy during Therapeutic Hypothermia. J Pediatr 2023; 261:113560. [PMID: 37321289 DOI: 10.1016/j.jpeds.2023.113560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Revised: 05/24/2023] [Accepted: 06/12/2023] [Indexed: 06/17/2023]
Abstract
OBJECTIVE To determine cerebral glucose concentration and its relationship with glucose infusion rate (GIR) and blood glucose concentration in neonatal encephalopathy during therapeutic hypothermia (TH). METHODS This was an observational study in which cerebral glucose during TH was quantified by magnetic resonance (MR) spectroscopy and compared with mean blood glucose at the time of scan. Clinical data (gestational age, birth weight, GIR, sedative use) that could affect glucose use were collected. The severity and pattern of brain injury on MR imaging were scored by a neuroradiologist. Student t test, Pearson correlation, repeated measures ANOVA, and multiple regression analysis were performed. RESULTS Three-hundred-sixty blood glucose values and 402 MR spectra from 54 infants (30 female infants; mean gestational age 38.6 ± 1.9 weeks) were analyzed. In total, 41 infants had normal-mild and 13 had moderate-severe injury. Median GIR and blood glucose during TH were 6.0 mg/kg/min (IQR 5-7) and 90 mg/dL (IQR 80-102), respectively. GIR did not correlate with blood or cerebral glucose. Cerebral glucose was significantly greater during than after TH (65.9 ± 22.9 vs 60.0 ± 25.2 mg/dL, P < .01), and there was a significant correlation between blood glucose and cerebral glucose during TH (basal ganglia: r = 0.42, thalamus: r = 0.42, cortical gray matter: r = 0.39, white matter: r = 0.39, all P < .01). There was no significant difference in cerebral glucose concentration in relation to injury severity or pattern. CONCLUSIONS During TH, cerebral glucose concentration is partly dependent on blood glucose concentration. Further studies to understand brain glucose use and optimal glucose concentrations during hypothermic neuroprotection are needed.
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Affiliation(s)
- Manas Tetarbe
- Division of Neonatology, Department of Pediatrics, LAC+USC Medical Center, Keck School of Medicine of USC, Los Angeles, CA
| | - Jessica L Wisnowski
- Division of Neonatology, Department of Pediatrics, Fetal and Neonatal Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA; Department of Radiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Eduardo Geyer
- Department of Pediatrics, Children's Hospital Los Angeles, Los Angeles, CA
| | - Benita Tamrazi
- Department of Radiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Thomas Wood
- Division of Neonatology, Department of Pediatrics, University of Washington School of Medicine, Seattle, WA
| | - Ulrike Mietzsch
- Division of Neonatology, Department of Pediatrics, University of Washington School of Medicine, Seattle, WA; Seattle Children's Hospital, Seattle, WA
| | - Stefan Blüml
- Department of Radiology, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA
| | - Tai-Wei Wu
- Division of Neonatology, Department of Pediatrics, Fetal and Neonatal Institute, Children's Hospital Los Angeles, Keck School of Medicine, University of Southern California, Los Angeles, CA.
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8
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Alnaqbi N, Mohammad MG, Hamoudi R, Mabondzo A, Harati R. Molecular Heterogeneity of the Brain Endothelium. Curr Issues Mol Biol 2023; 45:3462-3478. [PMID: 37185751 PMCID: PMC10136751 DOI: 10.3390/cimb45040227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Revised: 04/08/2023] [Accepted: 04/13/2023] [Indexed: 05/17/2023] Open
Abstract
The blood-brain barrier (BBB) is part of a neurovascular structure located in the brain's micro vessels, that is essential to maintain brain homeostasis, but prevents the brain uptake of most drugs. Because of its importance in neuro-pharmacotherapy, the BBB has been the subject of extensive research since its discovery over 100 years ago. Major advances in understanding the structure and function of the barrier have been made. Drugs are re-designed to cross the BBB. However, despite these efforts, overcoming the BBB efficiently to treat brain diseases safely remains challenging. The majority of BBB research studies focus on the BBB as a homogenous structure throughout the different brain regions. However, this simplification may lead to an inadequate understanding of the BBB function with significant therapeutic consequences. From this perspective, we analyzed the gene and protein expression profiles of the BBB in the micro vessels from the brains of mice that were isolated from two different brain regions, namely the cortex and the hippocampus. The expression profile of the inter-endothelial junctional protein (claudin-5), three ABC transporters (P-glycoprotein, Bcrp and Mrp-1), and three BBB receptors (lrp-1, TRF and GLUT-1) were analyzed. Our gene and protein analysis showed that the brain endothelium in the hippocampus exhibits different expression profiles compared to the brain cortex. Specifically, brain endothelial cells (BECs) of the hippocampus express higher gene levels of abcb1, abcg2, lrp1, and slc2a1 compared to the BECs of the cortex regions with a trend of increase for claudin-5, while BECs of the cortex express higher gene levels of abcc1 and trf compared to the hippocampus. At the protein levels, the P-gp expression was found to be significantly higher in the hippocampus compared to the cortex, while TRF was found to be up-regulated in the cortex. These data suggest that the structure and function of the BBB are not homogeneous, and imply that drugs are not delivered similarly among the different brain regions. Appreciation of the BBB heterogeneity by future research programs is thus critical for efficient drug delivery and the treatment of brain diseases.
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Affiliation(s)
- Nada Alnaqbi
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
- Research Institute for Medical and Health Sciences, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
| | - Mohammad G Mohammad
- Research Institute for Medical and Health Sciences, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
- Department of Medical Laboratories, College of Health Sciences, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
| | - Rifat Hamoudi
- Clinical Sciences Department, College of Medicine, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
- Division of Surgery and Interventional Science, University College London, London W1W 7EJ, UK
| | - Aloïse Mabondzo
- Department of Medicines and Healthcare Technologies, Paris-Saclay University, The French Alternative Energies and Atomic Energy Commission, 91191 Gif-sur-Yvette, France
| | - Rania Harati
- Department of Pharmacy Practice and Pharmacotherapeutics, College of Pharmacy, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
- Research Institute for Medical and Health Sciences, University of Sharjah, Sharjah P.O. Box 27272, United Arab Emirates
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9
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Dickie BR, Jin T, Wang P, Hinz R, Harris W, Boutin H, Parker GJ, Parkes LM, Matthews JC. Quantitative kinetic modelling and mapping of cerebral glucose transport and metabolism using glucoCESL MRI. J Cereb Blood Flow Metab 2022; 42:2066-2079. [PMID: 35748031 PMCID: PMC9580170 DOI: 10.1177/0271678x221108841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Chemical-exchange spin-lock (CESL) MRI can map regional uptake and utilisation of glucose in the brain at high spatial resolution (i.e sub 0.2 mm3 voxels). We propose two quantitative kinetic models to describe glucose-induced changes in tissue R1ρ and apply them to glucoCESL MRI data acquired in tumour-bearing and healthy rats. When assuming glucose transport is saturable, the maximal transport capacity (Tmax) measured in normal tissue was 3.2 ± 0.6 µmol/min/mL, the half saturation constant (Kt) was 8.8 ± 2.2 mM, the metabolic rate of glucose consumption (MRglc) was 0.21 ± 0.13 µmol/min/mL, and the cerebral blood volume (vb) was 0.006 ± 0.005 mL/mL. Values in tumour were: Tmax = 7.1 ± 2.7 µmol/min/mL, Kt = 14 ± 1.7 mM, MRglc = 0.22 ± 0.09 µmol/min/mL, vb = 0.030 ± 0.035 mL/mL. Tmax and Kt were significantly higher in tumour tissue than normal tissue (p = 0.006 and p = 0.011, respectively). When assuming glucose uptake also occurs via free diffusion, the free diffusion rate (kd) was 0.061 ± 0.017 mL/min/mL in normal tissue and 0.12 ± 0.042 mL/min/mL in tumour. These parameter estimates agree well with literature values obtained using other approaches (e.g. NMR spectroscopy).
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Affiliation(s)
- Ben R Dickie
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
| | - Tao Jin
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Ping Wang
- Department of Radiology, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Rainer Hinz
- Division of Informatics, Imaging, and Data Science, Faculty of Biology Medicine and Health, University of Manchester, Manchester, UK
| | - William Harris
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
| | - Hervé Boutin
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
| | - Geoff Jm Parker
- Bioxydyn Limited, Manchester, UK.,Centre for Medical Image Computing, Department of Medical Physics & Biomedical Engineering and Department of Neuroinflammation, University College London, London, UK
| | - Laura M Parkes
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
| | - Julian C Matthews
- Division of Neuroscience and Experimental Psychology, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.,Geoffrey Jefferson Brain Research Centre, Manchester Academic Health Science Centre, Manchester, UK
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Miller CO, Gantert LT, Previs SF, Chen Y, Anderson KD, Thomas JM, Sanacora G, Uslaner JM, Rothman DL, Mason GF. A Novel Biomarker of Neuronal Glutamate Metabolism in Nonhuman Primates Using Localized 1H-Magnetic Resonance Spectroscopy: Development and Effects of BNC375, an α7 Nicotinic Acetylcholine Receptor Positive Allosteric Modulator. BIOLOGICAL PSYCHIATRY. COGNITIVE NEUROSCIENCE AND NEUROIMAGING 2022; 7:598-606. [PMID: 33309567 PMCID: PMC8005500 DOI: 10.1016/j.bpsc.2020.09.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 09/20/2020] [Accepted: 09/21/2020] [Indexed: 06/03/2023]
Abstract
BACKGROUND The development of treatments for cognitive deficits associated with central nervous system disorders is currently a significant medical need. Despite the great need for such therapeutics, a significant challenge in the drug development process is the paucity of robust biomarkers to assess target modulation and guide clinical decisions. We developed a novel, translatable biomarker of neuronal glutamate metabolism, the 13C-glutamate+glutamine (Glx) H3:H4 labeling ratio, in nonhuman primates using localized 1H-magnetic resonance spectroscopy combined with 13C-glucose infusions. METHODS We began with numerical simulations in an established model of brain glutamate metabolism, showing that the 13C-Glx H3:H4 ratio should be a sensitive biomarker of neuronal tricarboxylic acid cycle activity, a key measure of overall neuronal metabolism. We showed that this biomarker can be measured reliably using a standard 1H-magnetic resonance spectroscopy method (point-resolved spectroscopy sequence/echo time = 20 ms), obviating the need for specialized hardware and pulse sequences typically used with 13C-magnetic resonance spectroscopy, thus improving overall clinical translatability. Finally, we used this biomarker in 8 male rhesus macaques before and after administration of the compound BNC375, a positive allosteric modulator of the α7 nicotinic acetylcholine receptor that enhances glutamate signaling ex vivo and elicits procognitive effects in preclinical species. RESULTS The 13C-Glx H3:H4 ratios in the monkeys showed that BNC375 increases neuronal metabolism in nonhuman primates in vivo, detectable on an individual basis. CONCLUSIONS This study demonstrates that the ratio of 13C-Glx H3:H4 labeling is a biomarker that may provide an objective readout of compounds affecting glutamatergic neurotransmission and could improve decision making for the development of therapeutic agents.
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Affiliation(s)
- Corin O Miller
- Department of Translational Imaging Biomarkers, Merck & Co., Kenilworth, New Jersey.
| | - Liza T Gantert
- Department of Translational Imaging Biomarkers, Merck & Co., Kenilworth, New Jersey
| | | | - Ying Chen
- Department of Chemistry, Merck & Co., Kenilworth, New Jersey
| | - Kenneth D Anderson
- Department of Pharmacology, Pharmacokinetics, and Drug Metabolism, Merck & Co., Kenilworth, New Jersey
| | - Justina M Thomas
- Department of Pharmacology, Pharmacokinetics, and Drug Metabolism, Merck & Co., Kenilworth, New Jersey
| | - Gerard Sanacora
- Department of Psychiatry, Yale University School of Medicine, New Haven, Connecticut
| | - Jason M Uslaner
- Department of Neuroscience, Merck & Co., Kenilworth, New Jersey
| | - Douglas L Rothman
- Department of Diagnostic Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut; Department of Biomedical Engineering Yale University School of Medicine, New Haven, Connecticut
| | - Graeme F Mason
- Department of Diagnostic Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, Connecticut
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11
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Sanchez-Rangel E, Gunawan F, Jiang L, Savoye M, Dai F, Coppoli A, Rothman DL, Mason GF, Hwang JJ. Reversibility of brain glucose kinetics in type 2 diabetes mellitus. Diabetologia 2022; 65:895-905. [PMID: 35247067 PMCID: PMC8960594 DOI: 10.1007/s00125-022-05664-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 12/02/2021] [Indexed: 11/20/2022]
Abstract
AIMS/HYPOTHESIS We have previously shown that individuals with uncontrolled type 2 diabetes have a blunted rise in brain glucose levels measured by 1H magnetic resonance spectroscopy. Here, we investigate whether reductions in HbA1c normalise intracerebral glucose levels. METHODS Eight individuals (two men, six women) with poorly controlled type 2 diabetes and mean ± SD age 44.8 ± 8.3 years, BMI 31.4 ± 6.1 kg/m2 and HbA1c 84.1 ± 16.2 mmol/mol (9.8 ± 1.4%) underwent 1H MRS scanning at 4 Tesla during a hyperglycaemic clamp (~12.21 mmol/l) to measure changes in cerebral glucose at baseline and after a 12 week intervention that improved glycaemic control through the use of continuous glucose monitoring, diabetes regimen intensification and frequent visits to an endocrinologist and nutritionist. RESULTS Following the intervention, mean ± SD HbA1c decreased by 24.3 ± 15.3 mmol/mol (2.1 ± 1.5%) (p=0.006), with minimal weight changes (p=0.242). Using a linear mixed-effects regression model to compare glucose time courses during the clamp pre and post intervention, the pre-intervention brain glucose level during the hyperglycaemic clamp was significantly lower than the post-intervention brain glucose (p<0.001) despite plasma glucose levels during the hyperglycaemic clamp being similar (p=0.266). Furthermore, the increases in brain glucose were correlated with the magnitude of improvement in HbA1c (r = 0.71, p=0.048). CONCLUSION/INTERPRETATION These findings highlight the potential reversibility of cerebral glucose transport capacity and metabolism that can occur in individuals with type 2 diabetes following improvement of glycaemic control. Trial registration ClinicalTrials.gov NCT03469492.
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Affiliation(s)
- Elizabeth Sanchez-Rangel
- Department of Internal Medicine/Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Felona Gunawan
- Department of Internal Medicine/Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA
| | - Lihong Jiang
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Mary Savoye
- Department of Pediatric Endocrinology and General Clinical Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Feng Dai
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, CT, USA
| | - Anastasia Coppoli
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT, USA
| | - Graeme F Mason
- Department of Radiology and Biomedical Imaging, Yale University School of Medicine, New Haven, CT, USA
- Department of Biomedical Engineering, Yale University School of Medicine, New Haven, CT, USA
- Department of Psychiatry, Yale University School of Medicine, New Haven, CT, USA
| | - Janice Jin Hwang
- Department of Internal Medicine/Section of Endocrinology, Yale University School of Medicine, New Haven, CT, USA.
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12
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Multiphasic modelling and computation of metastatic lung-cancer cell proliferation and atrophy in brain tissue based on experimental data. Biomech Model Mechanobiol 2021; 21:277-315. [PMID: 34918207 PMCID: PMC8807504 DOI: 10.1007/s10237-021-01535-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 11/23/2021] [Indexed: 02/07/2023]
Abstract
Cancer is one of the most serious diseases for human beings, especially when metastases come into play. In the present article, the example of lung-cancer metastases in the brain is used to discuss the basic problem of cancer growth and atrophy as a result of both nutrients and medication. As the brain itself is a soft tissue that is saturated by blood and interstitial fluid, the biomechanical description of the problem is based on the Theory of Porous Media enhanced by the results of medication tests carried out in in-vitro experiments on cancer-cell cultures. Based on theoretical and experimental results, the consideration of proliferation, necrosis and apoptosis of metastatic cancer cells is included in the description by so-called mass-production terms added to the mass balances of the brain skeleton and the interstitial fluid. Furthermore, the mass interaction of nutrients and medical drugs between the solid and the interstitial fluid and its influence on proliferation, necrosis and apoptosis of cancer cells are considered. As a result, the overall model is appropriate for the description of brain tumour treatment combined with stress and deformation induced by cancer growth in the skull.
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13
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Ruhm L, Avdievich N, Ziegs T, Nagel AM, De Feyter HM, de Graaf RA, Henning A. Deuterium metabolic imaging in the human brain at 9.4 Tesla with high spatial and temporal resolution. Neuroimage 2021; 244:118639. [PMID: 34637905 PMCID: PMC8591372 DOI: 10.1016/j.neuroimage.2021.118639] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 09/10/2021] [Accepted: 10/05/2021] [Indexed: 01/09/2023] Open
Abstract
PURPOSE To present first highly spatially resolved deuterium metabolic imaging (DMI) measurements of the human brain acquired with a dedicated coil design and a fast chemical shift imaging (CSI) sequence at an ultrahigh field strength of B0 = 9.4 T. 2H metabolic measurements with a temporal resolution of 10 min enabled the investigation of the glucose metabolism in healthy human subjects. METHODS The study was performed with a double-tuned coil with 10 TxRx channels for 1H and 8TxRx/2Rx channels for 2H and an Ernst angle 3D CSI sequence with a nominal spatial resolution of 2.97 ml and a temporal resolution of 10 min. RESULTS The metabolism of [6,6'-2H2]-labeled glucose due to the TCA cycle could be made visible in high resolution metabolite images of deuterated water, glucose and Glx over the entire human brain. CONCLUSION X-nuclei MRSI as DMI can highly benefit from ultrahigh field strength enabling higher temporal and spatial resolutions.
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Affiliation(s)
- Loreen Ruhm
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany; IMPRS for Cognitive and Systems Neuroscience, Eberhard-Karls University of Tübingen, Germany.
| | - Nikolai Avdievich
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany
| | - Theresia Ziegs
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany; IMPRS for Cognitive and Systems Neuroscience, Eberhard-Karls University of Tübingen, Germany
| | - Armin M Nagel
- Institute of Radiology, University Hospital Erlangen, Erlangen, Germany; Division of Medical Physics in Radiology, German Cancer Research Center (DKFZ), Heidelberg, Germany
| | - Henk M De Feyter
- Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States
| | - Robin A de Graaf
- Radiology and Biomedical Imaging, Yale University, New Haven, CT, United States
| | - Anke Henning
- High-Field MR Center, Max Planck Institute for Biological Cybernetics, Tübingen, Germany; Advanced Imaging Research Center, UT Southwestern Medical Center, Dallas/Texas, United States
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14
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Xu X, Sehgal AA, Yadav NN, Laterra J, Blair L, Blakeley J, Seidemo A, Coughlin JM, Pomper MG, Knutsson L, van Zijl PCM. d-glucose weighted chemical exchange saturation transfer (glucoCEST)-based dynamic glucose enhanced (DGE) MRI at 3T: early experience in healthy volunteers and brain tumor patients. Magn Reson Med 2020; 84:247-262. [PMID: 31872916 PMCID: PMC7083699 DOI: 10.1002/mrm.28124] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/30/2019] [Accepted: 11/19/2019] [Indexed: 12/11/2022]
Abstract
PURPOSE Dynamic glucose enhanced (DGE) MRI has shown potential for imaging glucose delivery and blood-brain barrier permeability at fields of 7T and higher. Here, we evaluated issues involved with translating d-glucose weighted chemical exchange saturation transfer (glucoCEST) experiments to the clinical field strength of 3T. METHODS Exchange rates of the different hydroxyl proton pools and the field-dependent T2 relaxivity of water in d-glucose solution were used to simulate the water saturation spectra (Z-spectra) and DGE signal differences as a function of static field strength B0 , radiofrequency field strength B1 , and saturation time tsat . Multislice DGE experiments were performed at 3T on 5 healthy volunteers and 3 glioma patients. RESULTS Simulations showed that DGE signal decreases with B0 , because of decreased contributions of glucoCEST and transverse relaxivity, as well as coalescence of the hydroxyl and water proton signals in the Z-spectrum. At 3T, because of this coalescence and increased interference of direct water saturation and magnetization transfer contrast, the DGE effect can be assessed over a broad range of saturation frequencies. Multislice DGE experiments were performed in vivo using a B1 of 1.6 µT and a tsat of 1 second, leading to a small glucoCEST DGE effect at an offset frequency of 2 ppm from the water resonance. Motion correction was essential to detect DGE effects reliably. CONCLUSION Multislice glucoCEST-based DGE experiments can be performed at 3T with sufficient temporal resolution. However, the effects are small and prone to motion influence. Therefore, motion correction should be used when performing DGE experiments at clinical field strengths.
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Affiliation(s)
- Xiang Xu
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - Akansha Ashvani Sehgal
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - Nirbhay N. Yadav
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
| | - John Laterra
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Lindsay Blair
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Jaishri Blakeley
- Department of Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Anina Seidemo
- Department of Medical Radiation Physics, Lund University, Lund, Sweden
| | - Jennifer M. Coughlin
- Department of Psychiatry, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Martin G. Pomper
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Linda Knutsson
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- Department of Medical Radiation Physics, Lund University, Lund, Sweden
| | - Peter C. M. van Zijl
- Russell H. Morgan Department of Radiology and Radiological Science, Johns Hopkins University School of Medicine, Baltimore, MD, USA
- F.M. Kirby Research Center for Functional Brain Imaging, Kennedy Krieger Research Institute, Baltimore, MD, USA
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15
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Lei H, Gruetter R. Metabolic and perfusion responses to acute hypoglycemia in the rat cortex: A non-invasive magnetic resonance approach. J Neurochem 2020; 154:71-83. [PMID: 32306383 DOI: 10.1111/jnc.15028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2019] [Revised: 04/10/2020] [Accepted: 04/14/2020] [Indexed: 11/30/2022]
Abstract
Hypoglycemia is critical condition during diabetic treatment that involves intensive insulin therapy, and it may impair brain function. We aimed to compare cortical responses of three hypoglycemic phases and the restoration of glycemia to control levels after a severe episode in rats using non-invasive perfusion magnetic resonance (MR) imaging and localized 1 H MR spectroscopy. Under light α-chloralose anesthesia, cortical blood flow (cCBF) was 42 ± 3 ml/100 g/min at euglycemia (~ 5 mM plasma glucose), was not altered at mild hypoglycemia I (42 ± 4 ml/100 g/min, 2-3.5 mM), increased to 60 ± 8 ml/100 g/min under moderate hypoglycemia II (1-2 mM) and amplified to 190 ± 35 ml/100 g/min at severe hypoglycemia III (< 1 mM). 1 H MRS revealed metabolic changes at hypoglycemia I without any perfusion alteration. At hypoglycemia III, glutamine and glutamate decreased, whereas aspartate increased. When animals subsequently regained glycemic control, not all metabolites returned to their control levels, for example, glutamine. Meanwhile, ascorbate was increased with amplified hypoglycemic severity, whereas glutathione was reduced; these compounds did not return to normal levels upon the restoration of glycemia. Our study is the first to report cCBF and neurochemical changes in cortex upon five glycemic stages. The cortical responses of different hypoglycemic phases would explain variable neuronal damages after hypoglycemia and might help identify the degrees of hypoglycemic insults and further improve alternative therapies.
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Affiliation(s)
- Hongxia Lei
- Animal Imaging Technology (AIT), Center for Biomedical Imaging Research (CIBM), Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland
| | - Rolf Gruetter
- Animal Imaging Technology (AIT), Center for Biomedical Imaging Research (CIBM), Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland.,Wuhan United Imaging Life Science Instruments Ltd., Wuhan, P.R.China.,Laboratory of Functional and Metabolic Imaging (LIFMET), Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland.,Department of Radiology, University of Geneva, Geneva, Switzerland
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16
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A thermodynamic function of glycogen in brain and muscle. Prog Neurobiol 2020; 189:101787. [PMID: 32151532 DOI: 10.1016/j.pneurobio.2020.101787] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 01/30/2020] [Accepted: 03/03/2020] [Indexed: 11/20/2022]
Abstract
Brain and muscle glycogen are generally thought to function as local glucose reserves, for use during transient mismatches between glucose supply and demand. However, quantitative measures show that glucose supply is likely never rate-limiting for energy metabolism in either brain or muscle under physiological conditions. These tissues nevertheless do utilize glycogen during increased energy demand, despite the availability of free glucose, and despite the ATP cost of cycling glucose through glycogen polymer. This seemingly wasteful process can be explained by considering the effect of glycogenolysis on the amount of energy obtained from ATP (ΔG'ATP). The amount of energy obtained from ATP is reduced by elevations in inorganic phosphate (Pi). Glycogen utilization sequesters Pi in the glycogen phosphorylase reaction and in downstream phosphorylated glycolytic intermediates, thereby buffering Pi elevations and maximizing energy yield at sites of rapid ATP consumption. This thermodynamic effect of glycogen may be particularly important in the narrow, spatially constrained astrocyte processes that ensheath neuronal synapses and in cells such as astrocytes and myocytes that release Pi from phosphocreatine during energy demand. The thermodynamic effect may also explain glycolytic super-compensation in brain when glycogen is not available, and aspects of exercise physiology in muscle glycogen phosphorylase deficiency (McArdle disease).
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17
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Rothman DL, de Graaf RA, Hyder F, Mason GF, Behar KL, De Feyter HM. In vivo 13 C and 1 H-[ 13 C] MRS studies of neuroenergetics and neurotransmitter cycling, applications to neurological and psychiatric disease and brain cancer. NMR IN BIOMEDICINE 2019; 32:e4172. [PMID: 31478594 DOI: 10.1002/nbm.4172] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 04/30/2019] [Accepted: 05/07/2019] [Indexed: 06/10/2023]
Abstract
In the last 25 years 13 C MRS has been established as the only noninvasive method for measuring glutamate neurotransmission and cell specific neuroenergetics. Although technically and experimentally challenging 13 C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, the high energy cost of brain function in the resting state and the role of altered neuroenergetics and neurotransmitter cycling in disease. In this paper we review the metabolic and neurotransmitter pathways that can be measured by 13 C MRS and key findings on the linkage between neuroenergetics, neurotransmitter cycling, and brain function. Applications of 13 C MRS to neurological and psychiatric disease as well as brain cancer are reviewed. Recent technological developments that may help to overcome spatial resolution and brain coverage limitations of 13 C MRS are discussed.
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Affiliation(s)
- Douglas L Rothman
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Departments of Radiology and Biomedical Imaging, and Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, 300 Cedar Street, P.O. Box 208043, New Haven, CT, USA
| | - Robin A de Graaf
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Fahmeed Hyder
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Graeme F Mason
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Kevin L Behar
- Department of Psychiatry, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Henk M De Feyter
- Departments of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
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18
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Villabona-Rueda A, Erice C, Pardo CA, Stins MF. The Evolving Concept of the Blood Brain Barrier (BBB): From a Single Static Barrier to a Heterogeneous and Dynamic Relay Center. Front Cell Neurosci 2019; 13:405. [PMID: 31616251 PMCID: PMC6763697 DOI: 10.3389/fncel.2019.00405] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 08/23/2019] [Indexed: 12/27/2022] Open
Abstract
The blood–brain barrier (BBB) helps maintain a tightly regulated microenvironment for optimal central nervous system (CNS) homeostasis and facilitates communications with the peripheral circulation. The brain endothelial cells, lining the brain’s vasculature, maintain close interactions with surrounding brain cells, e.g., astrocytes, pericytes and perivascular macrophages. This function facilitates critical intercellular crosstalk, giving rise to the concept of the neurovascular unit (NVU). The steady and appropriate communication between all components of the NVU is essential for normal CNS homeostasis and function, and dysregulation of one of its constituents can result in disease. Among the different brain regions, and along the vascular tree, the cellular composition of the NVU varies. Therefore, differential cues from the immediate vascular environment can affect BBB phenotype. To support the fluctuating metabolic and functional needs of the underlying neuropil, a specialized vascular heterogeneity is required. This is achieved by variances in barrier function, expression of transporters, receptors, and adhesion molecules. This mini-review will take you on a journey through evolving concepts surrounding the BBB, the NVU and beyond. Exploring classical experiments leading to new approaches will allow us to understand that the BBB is not merely a static separation between the brain and periphery but a closely regulated and interactive entity. We will discuss shifting paradigms, and ultimately aim to address the importance of BBB endothelial heterogeneity with regard to the function of the BBB within the NVU, and touch on its implications for different neuropathologies.
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Affiliation(s)
- Andres Villabona-Rueda
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Clara Erice
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
| | - Carlos A Pardo
- Department of Neurology, Division of Neuroimmunology and Neuroinfectious Disorders, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Monique F Stins
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Malaria Research Institute, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
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19
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Hwang JJ, Jiang L, Sanchez Rangel E, Fan X, Ding Y, Lam W, Leventhal J, Dai F, Rothman DL, Mason GF, Sherwin RS. Glycemic Variability and Brain Glucose Levels in Type 1 Diabetes. Diabetes 2019; 68:163-171. [PMID: 30327383 PMCID: PMC6302539 DOI: 10.2337/db18-0722] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 10/09/2018] [Indexed: 02/06/2023]
Abstract
The impact of glycemic variability on brain glucose transport kinetics among individuals with type 1 diabetes mellitus (T1DM) remains unclear. Fourteen individuals with T1DM (age 35 ± 4 years; BMI 26.0 ± 1.4 kg/m2; HbA1c 7.6 ± 0.3) and nine healthy control participants (age 32 ± 4; BMI 23.1 ± 0.8; HbA1c 5.0 ± 0.1) wore a continuous glucose monitor (Dexcom) to measure hypoglycemia, hyperglycemia, and glycemic variability for 5 days followed by 1H MRS scanning in the occipital lobe to measure the change in intracerebral glucose levels during a 2-h glucose clamp (target glucose concentration 220 mg/dL). Hyperglycemic clamps were also performed in a rat model of T1DM to assess regional differences in brain glucose transport and metabolism. Despite a similar change in plasma glucose levels during the hyperglycemic clamp, individuals with T1DM had significantly smaller increments in intracerebral glucose levels (P = 0.0002). Moreover, among individuals with T1DM, the change in brain glucose correlated positively with the lability index (r = 0.67, P = 0.006). Consistent with findings in humans, streptozotocin-treated rats had lower brain glucose levels in the cortex, hippocampus, and striatum compared with control rats. These findings that glycemic variability is associated with brain glucose levels highlight the need for future studies to investigate the impact of glycemic variability on brain glucose kinetics.
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Affiliation(s)
- Janice J Hwang
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Lihong Jiang
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
| | | | - Xiaoning Fan
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Yuyan Ding
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | - Wai Lam
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
| | | | - Feng Dai
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, CT
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
| | - Graeme F Mason
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, New Haven, CT
- Department of Psychiatry, Yale School of Medicine, New Haven, CT
| | - Robert S Sherwin
- Section of Endocrinology, Yale School of Medicine, New Haven, CT
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20
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Rothman DL, Dienel GA. Development of a Model to Test Whether Glycogenolysis Can Support Astrocytic Energy Demands of Na +, K +-ATPase and Glutamate-Glutamine Cycling, Sparing an Equivalent Amount of Glucose for Neurons. ADVANCES IN NEUROBIOLOGY 2019; 23:385-433. [PMID: 31667817 DOI: 10.1007/978-3-030-27480-1_14] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent studies of glycogen in brain have suggested a much more important role in brain energy metabolism and function than previously recognized, including findings of much higher than previously recognized concentrations, consumption at substantial rates compared with utilization of blood-borne glucose, and involvement in ion pumping and in neurotransmission and memory. However, it remains unclear how glycogenolysis is coupled to neuronal activity and provides support for neuronal as well as astroglial function. At present, quantitative aspects of glycogenolysis in brain functions are very difficult to assess due to its metabolic lability, heterogeneous distributions within and among cells, and extreme sensitivity to physiological stimuli. To begin to address this problem, the present study develops a model based on pathway fluxes, mass balance, and literature relevant to functions and turnover of pathways that intersect with glycogen mobilization. A series of equations is developed to describe the stoichiometric relationships between net glycogen consumption that is predominantly in astrocytes with the rate of the glutamate-glutamine cycle, rates of astrocytic and neuronal glycolytic and oxidative metabolism, and the energetics of sodium/potassium pumping in astrocytes and neurons during brain activation. Literature supporting the assumptions of the model is discussed in detail. The overall conclusion is that astrocyte glycogen metabolism is primarily coupled to neuronal function via fueling glycolytically pumping of Na+ and K+ and sparing glucose for neuronal oxidation, as opposed to previous proposals of coupling neurotransmission via glutamate transport, lactate shuttling, and neuronal oxidation of lactate.
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Affiliation(s)
- Douglas L Rothman
- Magnetic Resonance Research Center and Department of Radiology, Yale University, New Haven, CT, USA.
| | - Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA.,Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, USA
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21
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Benveniste H, Dienel G, Jacob Z, Lee H, Makaryus R, Gjedde A, Hyder F, Rothman DL. Trajectories of Brain Lactate and Re-visited Oxygen-Glucose Index Calculations Do Not Support Elevated Non-oxidative Metabolism of Glucose Across Childhood. Front Neurosci 2018; 12:631. [PMID: 30254563 PMCID: PMC6141825 DOI: 10.3389/fnins.2018.00631] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Accepted: 08/22/2018] [Indexed: 11/16/2022] Open
Abstract
Brain growth across childhood is a dynamic process associated with specific energy requirements. A disproportionately higher rate of glucose utilization (CMRglucose) compared with oxygen consumption (CMRO2) was documented in children's brain and suggestive of non-oxidative metabolism of glucose. Several candidate metabolic pathways may explain the CMRglucose-CMRO2 mismatch, and lactate production is considered a major contender. The ~33% excess CMRglucose equals 0.18 μmol glucose/g/min and predicts lactate release of 0.36 μmol/g/min. To validate such scenario, we measured the brain lactate concentration ([Lac]) in 65 children to determine if indeed lactate accumulates and is high enough to (1) account for the glucose consumed in excess of oxygen and (2) support a high rate of lactate efflux from the young brain. Across childhood, brain [Lac] was lower than predicted, and below the range for adult brain. In addition, we re-calculated the CMRglucose-CMRO2 mismatch itself by using updated lumped constant values. The calculated cerebral metabolic rate of lactate indicated a net influx of 0.04 μmol/g/min, or in terms of CMRglucose, of 0.02 μmol glucose/g/min. Accumulation of [Lac] and calculated efflux of lactate from brain are not consistent with the increase in non-oxidative metabolism of glucose. In addition, the value for the lumped constant for [18F]fluorodeoxyglucose has a high impact on calculated CMRglucose and use of updated values alters or eliminates the CMRglucose-CMRO2 mismatch in developing brain. We conclude that the presently-accepted notion of non-oxidative metabolism of glucose during childhood must be revisited and deserves further investigations.
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Affiliation(s)
- Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Gerald Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, United States.,Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, United States
| | - Zvi Jacob
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
| | - Hedok Lee
- Department of Anesthesiology, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Rany Makaryus
- Department of Anesthesiology, Stony Brook University, Stony Brook, NY, United States
| | - Albert Gjedde
- Department of Translational Neurobiology, University of Southern Denmark, Odense, Denmark
| | - Fahmeed Hyder
- Department of Biomedical Engineering & Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, CT, United States
| | - Douglas L Rothman
- Department of Biomedical Engineering & Radiology and Biomedical Imaging, Yale School of Medicine, Yale University, New Haven, CT, United States
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22
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Dienel GA. Metabolomic Assays of Postmortem Brain Extracts: Pitfalls in Extrapolation of Concentrations of Glucose and Amino Acids to Metabolic Dysregulation In Vivo in Neurological Diseases. Neurochem Res 2018; 44:2239-2260. [DOI: 10.1007/s11064-018-2611-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2018] [Revised: 08/05/2018] [Accepted: 08/06/2018] [Indexed: 01/03/2023]
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23
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Noumbissi ME, Galasso B, Stins MF. Brain vascular heterogeneity: implications for disease pathogenesis and design of in vitro blood-brain barrier models. Fluids Barriers CNS 2018; 15:12. [PMID: 29688865 PMCID: PMC5911972 DOI: 10.1186/s12987-018-0097-2] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Accepted: 04/13/2018] [Indexed: 12/22/2022] Open
Abstract
The vertebrate blood–brain barrier (BBB) is composed of cerebral microvascular endothelial cells (CEC). The BBB acts as a semi-permeable cellular interface that tightly regulates bidirectional molecular transport between blood and the brain parenchyma in order to maintain cerebral homeostasis. The CEC phenotype is regulated by a variety of factors, including cells in its immediate environment and within functional neurovascular units. The cellular composition of the brain parenchyma surrounding the CEC varies between different brain regions; this difference is clearly visible in grey versus white matter. In this review, we discuss evidence for the existence of brain vascular heterogeneity, focusing on differences between the vessels of the grey and white matter. The region-specific differences in the vasculature of the brain are reflective of specific functions of those particular brain areas. This BBB-endothelial heterogeneity may have implications for the course of pathogenesis of cerebrovascular diseases and neurological disorders involving vascular activation and dysfunction. This heterogeneity should be taken into account when developing BBB-neuro-disease models representative of specific brain areas.
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Affiliation(s)
- Midrelle E Noumbissi
- Malaria Research Institute, Dept. Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, SPH East 4135, Baltimore, MD, 21205, USA
| | - Bianca Galasso
- Malaria Research Institute, Dept. Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, SPH East 4135, Baltimore, MD, 21205, USA
| | - Monique F Stins
- Malaria Research Institute, Dept. Molecular Microbiology and Immunology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, SPH East 4135, Baltimore, MD, 21205, USA.
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24
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Blood-Brain Glucose Transfer in Alzheimer's disease: Effect of GLP-1 Analog Treatment. Sci Rep 2017; 7:17490. [PMID: 29235507 PMCID: PMC5727512 DOI: 10.1038/s41598-017-17718-y] [Citation(s) in RCA: 74] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Accepted: 11/29/2017] [Indexed: 12/12/2022] Open
Abstract
There are fewer than normal glucose transporters at the blood-brain barrier (BBB) in Alzheimer’s disease (AD). When reduced expression of transporters aggravates the symptoms of AD, the transporters become a potential target of therapy. The incretin hormone GLP-1 prevents the decline of cerebral metabolic rate for glucose (CMRglc) in AD, and GLP-1 may serve to raise transporter numbers. We hypothesized that the GLP-1 analog liraglutide would prevent the decline of CMRglc in AD by raising blood-brain glucose transfer, depending on the duration of disease. We randomized 38 patients with AD to treatment with liraglutide (n = 18) or placebo (n = 20) for 6 months, and determined the blood-brain glucose transfer capacity (Tmax) in the two groups and a healthy age matched control group (n = 6). In both AD groups at baseline, Tmax estimates correlated inversely with the duration of AD, as did the estimates of CMRglc that in turn were positively correlated with cognition. The GLP-1 analog treatment, compared to placebo, highly significantly raised the Tmax estimates of cerebral cortex from 0.72 to 1.1 umol/g/min, equal to Tmax estimates in healthy volunteers. The result is consistent with the claim that GLP-1 analog treatment restores glucose transport at the BBB.
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25
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Paech D, Schuenke P, Koehler C, Windschuh J, Mundiyanapurath S, Bickelhaupt S, Bonekamp D, Bäumer P, Bachert P, Ladd ME, Bendszus M, Wick W, Unterberg A, Schlemmer HP, Zaiss M, Radbruch A. T1ρ-weighted Dynamic Glucose-enhanced MR Imaging in the Human Brain. Radiology 2017. [DOI: 10.1148/radiol.2017162351] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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26
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De Feyter HM, Herzog RI, Steensma BR, Klomp DWJ, Brown PB, Mason GF, Rothman DL, de Graaf RA. Selective proton-observed, carbon-edited (selPOCE) MRS method for measurement of glutamate and glutamine 13 C-labeling in the human frontal cortex. Magn Reson Med 2017; 80:11-20. [PMID: 29134686 DOI: 10.1002/mrm.27003] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Revised: 10/02/2017] [Accepted: 10/20/2017] [Indexed: 11/10/2022]
Abstract
PURPOSE 13 C magnetic resonance spectroscopy (MRS) in combination with infusion of 13 C-labeled substrates has led to unique insights into human brain metabolism and neurotransmitter cycling. However, the low sensitivity of direct 13 C MRS and high radiofrequency power requirements has limited 13 C MRS studies to predominantly data acquisition in large volumes of the occipital cortex. The purpose of this study is to develop an MRS technique for localized detection of 13 C-labeling of glutamate and glutamine in the human frontal lobe. METHODS We used an indirect (1 H-[13 C]), proton-observed, carbon-edited MRS sequence (selPOCE) for detection of 13 C-labeled metabolites in relatively small volumes located in the frontal lobe at 4 T. The SelPOCE method allows for selective and separate detection of glutamate and glutamine resonances, which significantly overlap at magnetic field strengths used for clinical MRI. RESULTS Phantom data illustrate how selPOCE can be tuned to selectively detect 13 C labeling in different metabolites. Three-dimensional specific absorption rate simulations of radiofrequency power deposition show that the selPOCE method operates comfortably within the global and local Food and Drug Administration specific absorption rate guidelines. In vivo selPOCE data are presented, which were acquired from a 45-mL volume in the frontal lobe of healthy subjects. The in vivo data show the time-dependent 13 C-labeling of glutamate and glutamine during intravenous infusion of [1-13 C]-glucose. Metrics describing spectral fitting quality of the glutamate and glutamine resonances are reported. CONCLUSIONS The SelPOCE sequence allows the detection of 13 C-labeling in glutamate and glutamine from a relatively small volume in the human frontal lobe at low radiofrequency power requirements. Magn Reson Med 80:11-20, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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Affiliation(s)
- Henk M De Feyter
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Raimund I Herzog
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Bart R Steensma
- Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Dennis W J Klomp
- Department of Radiology, University Medical Center Utrecht, Utrecht, Netherlands
| | - Peter B Brown
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Graeme F Mason
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Robin A de Graaf
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA.,Department of Biomedical Engineering, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA
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27
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Hwang JJ, Jiang L, Hamza M, Sanchez Rangel E, Dai F, Belfort-DeAguiar R, Parikh L, Koo BB, Rothman DL, Mason G, Sherwin RS. Blunted rise in brain glucose levels during hyperglycemia in adults with obesity and T2DM. JCI Insight 2017; 2:95913. [PMID: 29046482 DOI: 10.1172/jci.insight.95913] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Accepted: 09/21/2017] [Indexed: 12/22/2022] Open
Abstract
In rodent models, obesity and hyperglycemia alter cerebral glucose metabolism and glucose transport into the brain, resulting in disordered cerebral function as well as inappropriate responses to homeostatic and hedonic inputs. Whether similar findings are seen in the human brain remains unclear. In this study, 25 participants (9 healthy participants; 10 obese nondiabetic participants; and 6 poorly controlled, insulin- and metformin-treated type 2 diabetes mellitus (T2DM) participants) underwent 1H magnetic resonance spectroscopy scanning in the occipital lobe to measure the change in intracerebral glucose levels during a 2-hour hyperglycemic clamp (glucose ~220 mg/dl). The change in intracerebral glucose was significantly different across groups after controlling for age and sex, despite similar plasma glucose levels at baseline and during hyperglycemia. Compared with lean participants, brain glucose increments were lower in participants with obesity and T2DM. Furthermore, the change in brain glucose correlated inversely with plasma free fatty acid (FFA) levels during hyperglycemia. These data suggest that obesity and poorly controlled T2DM progressively diminish brain glucose responses to hyperglycemia, which has important implications for understanding not only the altered feeding behavior, but also the adverse neurocognitive consequences associated with obesity and T2DM.
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Affiliation(s)
- Janice J Hwang
- Section of Endocrinology, Department of Internal Medicine, and
| | - Lihong Jiang
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
| | - Muhammad Hamza
- Section of Endocrinology, Department of Internal Medicine, and
| | | | - Feng Dai
- Yale Center for Analytical Sciences, Yale School of Public Health, New Haven, Connecticut, USA
| | | | - Lisa Parikh
- Section of Endocrinology, Department of Internal Medicine, and
| | - Brian B Koo
- Department of Neurology, Yale School of Medicine, New Haven, Connecticut, USA
| | - Douglas L Rothman
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
| | - Graeme Mason
- Department of Radiology & Biomedical Imaging, Yale School of Medicine, New Haven, Connecticut, USA
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28
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Seaquist ER, Moheet A, Kumar A, Deelchand DK, Terpstra M, Kubisiak K, Eberly LE, Henry PG, Joers JM, Öz G. Hypothalamic Glucose Transport in Humans During Experimentally Induced Hypoglycemia-Associated Autonomic Failure. J Clin Endocrinol Metab 2017; 102:3571-3580. [PMID: 28911152 PMCID: PMC5587056 DOI: 10.1210/jc.2017-00477] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 07/17/2017] [Indexed: 01/15/2023]
Abstract
CONTEXT Upregulated brain glucose transport in response to recurrent hypoglycemia may contribute to the development of hypoglycemia-associated autonomic failure (HAAF) and impaired awareness of hypoglycemia. Whether recurrent hypoglycemia alters glucose transport in the hypothalamus is unknown. OBJECTIVE To test the hypothesis that hypothalamic glucose transport will increase in healthy volunteers preconditioned with recurrent hypoglycemia to induce HAAF. SETTING University medical center. DESIGN AND PARTICIPANTS Thirteen healthy subjects underwent paired euglycemic and hypoglycemic preconditioning studies separated by at least 1 month. Following preconditioning, hypothalamic glucose transport was measured by magnetic resonance spectroscopy (MRS) in the afternoon on day 2 of each preconditioning protocol. OUTCOME MEASURE The ratio of maximal transport rate to cerebral metabolic rate of glucose (Tmax/CMRglc), obtained from MRS-measured glucose in the hypothalamus as a function of plasma glucose. RESULTS HAAF was successfully induced based on lower epinephrine, glucagon, and cortisol during the third vs first hypoglycemic preconditioning clamp (P ≤ 0.01). Hypothalamic glucose transport was not different following recurrent euglycemia vs hypoglycemia (Tmax/CMRglc 1.62 ± 0.09 after euglycemia preconditioning and 1.75 ± 0.14 after hypoglycemia preconditioning; P was not significant). Hypothalamic glucose concentrations measured by MRS were not different following the two preconditioning protocols. CONCLUSIONS Glucose transport kinetics in the hypothalamus of healthy humans with experimentally induced HAAF were not different from those measured without HAAF. Future studies of patients with diabetes and impaired awareness of hypoglycemia will be necessary to determine if the existence of the diabetes state is required for this adaptation to hypoglycemia to occur.
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Affiliation(s)
- Elizabeth R. Seaquist
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Amir Moheet
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Anjali Kumar
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota 55455
| | - Dinesh K. Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Melissa Terpstra
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Kristine Kubisiak
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455
| | - Lynn E. Eberly
- Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota 55455
| | - Pierre-Gilles Henry
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - James M. Joers
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota 55455
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29
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Ratner V, Gao Y, Lee H, Elkin R, Nedergaard M, Benveniste H, Tannenbaum A. Cerebrospinal and interstitial fluid transport via the glymphatic pathway modeled by optimal mass transport. Neuroimage 2017; 152:530-537. [PMID: 28323163 PMCID: PMC5490081 DOI: 10.1016/j.neuroimage.2017.03.021] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 03/07/2017] [Accepted: 03/10/2017] [Indexed: 11/26/2022] Open
Abstract
The glymphatic pathway is a system which facilitates continuous cerebrospinal fluid (CSF) and interstitial fluid (ISF) exchange and plays a key role in removing waste products from the rodent brain. Dysfunction of the glymphatic pathway may be implicated in the pathophysiology of Alzheimer's disease. Intriguingly, the glymphatic system is most active during deep wave sleep general anesthesia. By using paramagnetic tracers administered into CSF of rodents, we previously showed the utility of MRI in characterizing a macroscopic whole brain view of glymphatic transport but we have yet to define and visualize the specific flow patterns. Here we have applied an alternative mathematical analysis approach to a dynamic time series of MRI images acquired every 4min over ∼3h in anesthetized rats, following administration of a small molecular weight paramagnetic tracer into the CSF reservoir of the cisterna magna. We use Optimal Mass Transport (OMT) to model the glymphatic flow vector field, and then analyze the flow to find the network of CSF-ISF flow channels. We use 3D visualization computational tools to visualize the OMT defined network of CSF-ISF flow channels in relation to anatomical and vascular key landmarks from the live rodent brain. The resulting OMT model of the glymphatic transport network agrees largely with the current understanding of the glymphatic transport patterns defined by dynamic contrast-enhanced MRI revealing key CSF transport pathways along the ventral surface of the brain with a trajectory towards the pineal gland, cerebellum, hypothalamus and olfactory bulb. In addition, the OMT analysis also revealed some interesting previously unnoticed behaviors regarding CSF transport involving parenchymal streamlines moving from ventral reservoirs towards the surface of the brain, olfactory bulb and large central veins.
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Affiliation(s)
- Vadim Ratner
- Department of Computer Science, Stony Brook University, Stony Brook, NY 11790, USA
| | - Yi Gao
- Department of Biomedical Informatics, Stony Brook University, Stony Brook, NY 11790, USA
| | - Hedok Lee
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT 06519, USA
| | - Rena Elkin
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11790, USA
| | | | - Helene Benveniste
- Department of Anesthesiology, Yale School of Medicine, New Haven, CT 06519, USA
| | - Allen Tannenbaum
- Department of Applied Mathematics and Statistics, Stony Brook University, Stony Brook, NY 11790, USA; Department of Computer Science, Stony Brook University, Stony Brook, NY 11790, USA.
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30
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Joers JM, Deelchand DK, Kumar A, Moheet A, Seaquist E, Henry PG, Öz G. Measurement of Hypothalamic Glucose Under Euglycemia and Hyperglycemia by MRI at 3T. J Magn Reson Imaging 2017; 45:681-691. [PMID: 27402249 PMCID: PMC5575789 DOI: 10.1002/jmri.25383] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2016] [Accepted: 06/21/2016] [Indexed: 12/26/2022] Open
Abstract
PURPOSE To evaluate the feasibility of using a clinical magnetic resonance (MR) system and MR spectroscopy (MRS) to measure glucose concentration changes in the human hypothalamus, a structure central to whole-body glucose regulation. SUBJECTS AND METHODS A time series of MR spectra (semi-LASER, TE = 28 msec), localized to the bilateral hypothalamus (∼1.6 ml) were obtained at 3T in six healthy subjects at baseline (euglycemia) and during a ∼65-70-minute-long hyperglycemic clamp in 11-minute blocks with interleaved T1 FLASH images to retrospectively assess head motion, and track changes in cerebrospinal fluid (CSF) partial volume. The LCModel was used to quantify the sum of glucose and taurine concentrations, [Glc+Tau], along with their associated Cramér-Rao lower bounds (CRLB). RESULTS Spectral quality allowed quantification of [Glc+Tau] (sum reported due to high negative correlation between these metabolites) with CRLB <25% in 35/36 timepoints during hyperglycemia. Increased [Glc+Tau] was observed with hyperglycemia in all subjects, but most reliably in those with plasma glucose targets ≥300 mg/dl. For these subjects, [Glc+Tau]baseline (n = 4) was 1.5 (±0.3, SD) mM, and increased to 4.5 (±1.1) mM (n = 16) for timepoints acquired ≥25 minutes after onset of the clamp, with 15/16 timepoints having no overlap of 95% confidence intervals (CIs) between baseline and hyperglycemia. Preliminary analysis revealed a linear (1:5) relationship between hypothalamus-blood glucose concentrations. CONCLUSION It is feasible to measure glucose concentration changes in the human hypothalamus using a standard 3T scanner and a short-echo semi-LASER sequence by utilizing retrospective motion tracking, CSF correction, predetermined quality acceptance criteria, and hyperglycemic blood glucose levels ≥300 mg/dl. LEVEL OF EVIDENCE 2 J. Magn. Reson. Imaging 2017;45:681-691.
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Affiliation(s)
- James M. Joers
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Dinesh K. Deelchand
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Anjali Kumar
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Amir Moheet
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Elizabeth Seaquist
- Division of Diabetes, Endocrinology and Metabolism, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
| | - Pierre-Gilles Henry
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
| | - Gülin Öz
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
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31
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Dienel GA, Rothman DL, Nordström CH. Microdialysate concentration changes do not provide sufficient information to evaluate metabolic effects of lactate supplementation in brain-injured patients. J Cereb Blood Flow Metab 2016; 36:1844-1864. [PMID: 27604313 PMCID: PMC5094313 DOI: 10.1177/0271678x16666552] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Accepted: 08/03/2016] [Indexed: 12/31/2022]
Abstract
Cerebral microdialysis is a widely used clinical tool for monitoring extracellular concentrations of selected metabolites after brain injury and to guide neurocritical care. Extracellular glucose levels and lactate/pyruvate ratios have high diagnostic value because they can detect hypoglycemia and deficits in oxidative metabolism, respectively. In addition, patterns of metabolite concentrations can distinguish between ischemia and mitochondrial dysfunction, and are helpful to choose and evaluate therapy. Increased intracranial pressure can be life-threatening after brain injury, and hypertonic solutions are commonly used for pressure reduction. Recent reports have advocated use of hypertonic sodium lactate, based on claims that it is glucose sparing and provides an oxidative fuel for injured brain. However, changes in extracellular concentrations in microdialysate are not evidence that a rise in extracellular glucose level is beneficial or that lactate is metabolized and improves neuroenergetics. The increase in glucose concentration may reflect inhibition of glycolysis, glycogenolysis, and pentose phosphate shunt pathway fluxes by lactate flooding in patients with mitochondrial dysfunction. In such cases, lactate will not be metabolizable and lactate flooding may be harmful. More rigorous approaches are required to evaluate metabolic and physiological effects of administration of hypertonic sodium lactate to brain-injured patients.
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Affiliation(s)
- Gerald A Dienel
- Department of Neurology, University of Arkansas for Medical Sciences, Little Rock, AR, USA, and Department of Cell Biology and Physiology, University of New Mexico, Albuquerque, NM, USA
| | - Douglas L Rothman
- Department of Radiology and Biomedical Imaging, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT, USA
| | - Carl-Henrik Nordström
- Department of Neurosurgery, Lund University Hospital, Lund, Sweden, and Department of Neurosurgery, Odense University Hospital, Odense, Denmark
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32
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Rooijackers HMM, Wiegers EC, Tack CJ, van der Graaf M, de Galan BE. Brain glucose metabolism during hypoglycemia in type 1 diabetes: insights from functional and metabolic neuroimaging studies. Cell Mol Life Sci 2016; 73:705-22. [PMID: 26521082 PMCID: PMC4735263 DOI: 10.1007/s00018-015-2079-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2015] [Revised: 10/16/2015] [Accepted: 10/20/2015] [Indexed: 12/30/2022]
Abstract
Hypoglycemia is the most frequent complication of insulin therapy in patients with type 1 diabetes. Since the brain is reliant on circulating glucose as its main source of energy, hypoglycemia poses a threat for normal brain function. Paradoxically, although hypoglycemia commonly induces immediate decline in cognitive function, long-lasting changes in brain structure and cognitive function are uncommon in patients with type 1 diabetes. In fact, recurrent hypoglycemia initiates a process of habituation that suppresses hormonal responses to and impairs awareness of subsequent hypoglycemia, which has been attributed to adaptations in the brain. These observations sparked great scientific interest into the brain's handling of glucose during (recurrent) hypoglycemia. Various neuroimaging techniques have been employed to study brain (glucose) metabolism, including PET, fMRI, MRS and ASL. This review discusses what is currently known about cerebral metabolism during hypoglycemia, and how findings obtained by functional and metabolic neuroimaging techniques contributed to this knowledge.
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Affiliation(s)
- Hanne M M Rooijackers
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands.
| | - Evita C Wiegers
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Cees J Tack
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
| | - Marinette van der Graaf
- Department of Radiology and Nuclear Medicine, Radboud University Medical Center, Nijmegen, The Netherlands
- Department of Pediatrics, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Bastiaan E de Galan
- Department of Internal Medicine 463, Radboud University Medical Center, PO Box 9101, 6500 HB, Nijmegen, The Netherlands
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Mapping brain glucose uptake with chemical exchange-sensitive spin-lock magnetic resonance imaging. J Cereb Blood Flow Metab 2014; 34:1402-10. [PMID: 24865996 PMCID: PMC4126103 DOI: 10.1038/jcbfm.2014.97] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 04/08/2014] [Accepted: 05/10/2014] [Indexed: 11/08/2022]
Abstract
Uptake of administered D-glucose (Glc) or 2-deoxy-D-glucose (2DG) has been indirectly mapped through the chemical exchange (CE) between glucose hydroxyl and water protons using CE-dependent saturation transfer (glucoCEST) magnetic resonance imaging (MRI). We propose an alternative technique-on-resonance CE-sensitive spin-lock (CESL) MRI-to enhance responses to glucose changes. Phantom data and simulations suggest higher sensitivity for this 'glucoCESL' technique (versus glucoCEST) in the intermediate CE regime relevant to glucose. Simulations of CESL signals also show insensitivity to B0-fluctuations. Several findings are apparent from in vivo glucoCESL studies of rat brain at 9.4 Tesla with intravenous injections. First, dose-dependent responses are nearly linearly for 0.25-, 0.5-, and 1-g/kg Glc administration (obtained with 12-second temporal resolution), with changes robustly detected for all doses. Second, responses at a matched dose of 1 g/kg are much larger and persist for a longer duration for 2DG versus Glc administration, and are minimal for mannitol as an osmolality control. And third, with similar increases in steady-state blood glucose levels, glucoCESL responses are ∼2.2 times higher for 2DG versus Glc, consistent with their different metabolic properties. Overall, we show that glucoCESL MRI could be a highly sensitive and quantifiable tool for glucose transport and metabolism studies.
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Sinha S, Ekka M, Sharma U, P R, Pandey RM, Jagannathan NR. Assessment of changes in brain metabolites in Indian patients with type-2 diabetes mellitus using proton magnetic resonance spectroscopy. BMC Res Notes 2014; 7:41. [PMID: 24433580 PMCID: PMC3897881 DOI: 10.1186/1756-0500-7-41] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 01/10/2014] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The brain is a target for diabetic end-organ damage, though the pathophysiology of diabetic encephalopathy is still not well understood. The aim of the present study was to investigate the effect of diabetes on the metabolic profile of brain of patients having diabetes in comparison to healthy controls, using in-vivo magnetic resonance spectroscopy to get an insight into the pathophysiology of cerebral damages caused due to diabetes. METHODS Single voxel proton magnetic resonance spectroscopy (1H-MRS) was performed at 1.5 T on right frontal, right parieto-temporal and right parieto-occipital white matter regions of the brain of 10 patients having type-2 diabetes along with 7 healthy controls. Absolute concentration of N-acetylaspartate (NAA), choline (cho), myo-inositol (mI), glutamate (Glu) and glutamine (Gln), creatine (Cr) and glucose were determined using the LC-Model and compared between the two groups. RESULTS The concentration of N-acetylaspartate was significantly lower in the right frontal [4.35 ±0.69 vs. 5.23 ±0.74; p = 0.03] and right parieto-occipital region [5.44 ±0.52 vs.6.08 ±0.25; p = 0.02] of the brain of diabetics as compared to the control group. The concentrations of glutamate and glutamine were found to be significantly higher in the right frontal region of the brain [7.98 ±2.57 vs. 5.32 ±1.43; P = 0.01] in diabetics. Glucose levels were found significantly elevated in all the three regions of the brain in diabetics as compared to the control group. However, no significant changes in levels of choline, myo-inositol and creatine were observed in the three regions of the brain examined among the two groups. CONCLUSIONS 1H-MRS analysis indicates that type-2 diabetes mellitus may cause subtle changes in the metabolic profile of the brain. Decreased concentrations of NAA might be indicative of decreased neuronal viability in diabetics while elevated concentrations of Gln and Glu might be related to the fluid imbalance resulting from disruption of glucose homeostasis.
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Affiliation(s)
- Sanjeev Sinha
- Department of Medicine, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India.
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Bal S, Goyal M, Smith E, Demchuk AM. Central nervous system imaging in diabetic cerebrovascular diseases and white matter hyperintensities. HANDBOOK OF CLINICAL NEUROLOGY 2014; 126:291-315. [PMID: 25410230 DOI: 10.1016/b978-0-444-53480-4.00021-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Diabetes mellitus is an important vascular risk factor for cerebrovascular disease. This occurs through pathophysiologic changes to the microcirculation as arteriolosclerosis and to the macrocirculation as large artery atherosclerosis. Imaging techniques can provide detailed visualization of the cerebrovasculature using CT (computed tomography) angiography and MR (magnetic resonance) angiography. Newer techniques focused on advanced parenchymal imaging include CT perfusion, quantitative MRI, and diffusion tensor imaging; each identifies brain lesion burden due to diabetes mellitus. These imaging approaches have provided insights into the diabetes mellitus brain and cerebral circulation pathophysiology. Imaging has taught us that diabetics develop cerebral atrophy, silent infarcts, and white matter disease more rapidly than other patient populations. Longitudinal studies are needed to quantify the rate and extent of such structural brain and blood vessel changes and how they relate to cognitive decline. Diabetes prevention and treatment strategies will then be possible to slow the development of such changes.
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Affiliation(s)
- Simerpreet Bal
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada
| | - Mayank Goyal
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada
| | - Eric Smith
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada
| | - Andrew M Demchuk
- Department of Clinical Neurosciences and Radiology, Foothills Medical Centre, Calgary, Alberta, Canada.
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Rae CD. A Guide to the Metabolic Pathways and Function of Metabolites Observed in Human Brain 1H Magnetic Resonance Spectra. Neurochem Res 2013; 39:1-36. [PMID: 24258018 DOI: 10.1007/s11064-013-1199-5] [Citation(s) in RCA: 324] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2013] [Revised: 11/08/2013] [Accepted: 11/11/2013] [Indexed: 12/20/2022]
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Cura AJ, Carruthers A. Role of monosaccharide transport proteins in carbohydrate assimilation, distribution, metabolism, and homeostasis. Compr Physiol 2013; 2:863-914. [PMID: 22943001 DOI: 10.1002/cphy.c110024] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The facilitated diffusion of glucose, galactose, fructose, urate, myoinositol, and dehydroascorbicacid in mammals is catalyzed by a family of 14 monosaccharide transport proteins called GLUTs. These transporters may be divided into three classes according to sequence similarity and function/substrate specificity. GLUT1 appears to be highly expressed in glycolytically active cells and has been coopted in vitamin C auxotrophs to maintain the redox state of the blood through transport of dehydroascorbate. Several GLUTs are definitive glucose/galactose transporters, GLUT2 and GLUT5 are physiologically important fructose transporters, GLUT9 appears to be a urate transporter while GLUT13 is a proton/myoinositol cotransporter. The physiologic substrates of some GLUTs remain to be established. The GLUTs are expressed in a tissue specific manner where affinity, specificity, and capacity for substrate transport are paramount for tissue function. Although great strides have been made in characterizing GLUT-catalyzed monosaccharide transport and mapping GLUT membrane topography and determinants of substrate specificity, a unifying model for GLUT structure and function remains elusive. The GLUTs play a major role in carbohydrate homeostasis and the redistribution of sugar-derived carbons among the various organ systems. This is accomplished through a multiplicity of GLUT-dependent glucose sensing and effector mechanisms that regulate monosaccharide ingestion, absorption,distribution, cellular transport and metabolism, and recovery/retention. Glucose transport and metabolism have coevolved in mammals to support cerebral glucose utilization.
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Affiliation(s)
- Anthony J Cura
- Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Lanz B, Gruetter R, Duarte JMN. Metabolic Flux and Compartmentation Analysis in the Brain In vivo. Front Endocrinol (Lausanne) 2013; 4:156. [PMID: 24194729 PMCID: PMC3809570 DOI: 10.3389/fendo.2013.00156] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Accepted: 10/07/2013] [Indexed: 12/16/2022] Open
Abstract
Through significant developments and progresses in the last two decades, in vivo localized nuclear magnetic resonance spectroscopy (MRS) became a method of choice to probe brain metabolic pathways in a non-invasive way. Beside the measurement of the total concentration of more than 20 metabolites, (1)H MRS can be used to quantify the dynamics of substrate transport across the blood-brain barrier by varying the plasma substrate level. On the other hand, (13)C MRS with the infusion of (13)C-enriched substrates enables the characterization of brain oxidative metabolism and neurotransmission by incorporation of (13)C in the different carbon positions of amino acid neurotransmitters. The quantitative determination of the biochemical reactions involved in these processes requires the use of appropriate metabolic models, whose level of details is strongly related to the amount of data accessible with in vivo MRS. In the present work, we present the different steps involved in the elaboration of a mathematical model of a given brain metabolic process and its application to the experimental data in order to extract quantitative brain metabolic rates. We review the recent advances in the localized measurement of brain glucose transport and compartmentalized brain energy metabolism, and how these reveal mechanistic details on glial support to glutamatergic and GABAergic neurons.
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Affiliation(s)
- Bernard Lanz
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Rolf Gruetter
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Radiology, University of Lausanne, Lausanne, Switzerland
- Department of Radiology, University of Geneva, Geneva, Switzerland
| | - João M. N. Duarte
- Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Department of Radiology, University of Lausanne, Lausanne, Switzerland
- *Correspondence: João M. N. Duarte, Laboratory for Functional and Metabolic Imaging, Ecole Polytechnique Fédérale de Lausanne, Bâtiment CH, Station 6, CH-1015 Lausanne, Switzerland e-mail:
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Herzog RI, Jiang L, Herman P, Zhao C, Sanganahalli BG, Mason GF, Hyder F, Rothman DL, Sherwin RS, Behar KL. Lactate preserves neuronal metabolism and function following antecedent recurrent hypoglycemia. J Clin Invest 2013; 123:1988-98. [PMID: 23543056 DOI: 10.1172/jci65105] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Accepted: 01/31/2013] [Indexed: 12/30/2022] Open
Abstract
Hypoglycemia occurs frequently during intensive insulin therapy in patients with both type 1 and type 2 diabetes and remains the single most important obstacle in achieving tight glycemic control. Using a rodent model of hypoglycemia, we demonstrated that exposure to antecedent recurrent hypoglycemia leads to adaptations of brain metabolism so that modest increments in circulating lactate allow the brain to function normally under acute hypoglycemic conditions. We characterized 3 major factors underlying this effect. First, we measured enhanced transport of lactate both into as well as out of the brain that resulted in only a small increase of its contribution to total brain oxidative capacity, suggesting that it was not the major fuel. Second, we observed a doubling of the glucose contribution to brain metabolism under hypoglycemic conditions that restored metabolic activity to levels otherwise only observed at euglycemia. Third, we determined that elevated lactate is critical for maintaining glucose metabolism under hypoglycemia, which preserves neuronal function. These unexpected findings suggest that while lactate uptake was enhanced, it is insufficient to support metabolism as an alternate substrate to replace glucose. Lactate is, however, able to modulate metabolic and neuronal activity, serving as a "metabolic regulator" instead.
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Affiliation(s)
- Raimund I Herzog
- Department of Internal Medicine, Section of Endocrinology, Yale School of Medicine, New Haven, Connecticut 06520-8040, USA.
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40
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Affiliation(s)
- Elizabeth R Seaquist
- Division of Endocrinology and Diabetes, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA.
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41
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van de Ven KC, van der Graaf M, Tack CJ, Heerschap A, de Galan BE. Steady-state brain glucose concentrations during hypoglycemia in healthy humans and patients with type 1 diabetes. Diabetes 2012; 61:1974-7. [PMID: 22688331 PMCID: PMC3402320 DOI: 10.2337/db11-1778] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The objective of this study was to investigate the relationship between plasma and brain glucose levels during euglycemia and hypoglycemia in healthy subjects and patients with type 1 diabetes mellitus (T1DM). Hyperinsulinemic euglycemic (5 mmol/L) and hypoglycemic (3 mmol/L) [1-(13)C]glucose clamps were performed in eight healthy subjects and nine patients with uncomplicated T1DM (HbA(1c) 7.7 ± 1.4%). Brain glucose levels were measured by (13)C magnetic resonance spectroscopy. Linear regression analysis was used to fit the relationship between plasma and brain glucose levels and calculate reversible Michaelis-Menten (MM) kinetic parameters. Brain glucose values during euglycemia (1.1 ± 0.4 μmol/g vs. 1.1 ± 0.3 μmol/g; P = 0.95) and hypoglycemia (0.5 ± 0.2 μmol/g vs. 0.6 ± 0.3 μmol/g; P = 0.52) were comparable between healthy subjects and T1DM patients. MM kinetic parameters of combined data were calculated to be maximum transport rate/cerebral metabolic rate of glucose (T(max)/CMR(glc)) = 2.25 ± 0.32 and substrate concentration at half maximal transport (K(t)) = 1.53 ± 0.88 mmol/L, which is in line with previously published data obtained under hyperglycemic conditions. In conclusion, the linear MM relationship between plasma and brain glucose can be extended to low plasma glucose levels. We found no evidence that the plasma to brain glucose relationship or the kinetics describing glucose transport over the blood-brain barrier differ between healthy subjects and patients with uncomplicated, reasonably well-controlled T1DM.
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Affiliation(s)
- Kim C.C. van de Ven
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - Marinette van der Graaf
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
- Clinical Physics Laboratory, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - Cees J. Tack
- Department of General Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - Arend Heerschap
- Department of Radiology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - Bastiaan E. de Galan
- Department of General Internal Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
- Corresponding author: Bastiaan E. de Galan,
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Abstract
Metabolic signals are used for imaging and spectroscopic studies of brain function and disease and to elucidate the cellular basis of neuroenergetics. The major fuel for activated neurons and the models for neuron–astrocyte interactions have been controversial because discordant results are obtained in different experimental systems, some of which do not correspond to adult brain. In rats, the infrastructure to support the high energetic demands of adult brain is acquired during postnatal development and matures after weaning. The brain's capacity to supply and metabolize glucose and oxygen exceeds demand over a wide range of rates, and the hyperaemic response to functional activation is rapid. Oxidative metabolism provides most ATP, but glycolysis is frequently preferentially up-regulated during activation. Underestimation of glucose utilization rates with labelled glucose arises from increased lactate production, lactate diffusion via transporters and astrocytic gap junctions, and lactate release to blood and perivascular drainage. Increased pentose shunt pathway flux also causes label loss from C1 of glucose. Glucose analogues are used to assay cellular activities, but interpretation of results is uncertain due to insufficient characterization of transport and phosphorylation kinetics. Brain activation in subjects with low blood-lactate levels causes a brain-to-blood lactate gradient, with rapid lactate release. In contrast, lactate flooding of brain during physical activity or infusion provides an opportunistic, supplemental fuel. Available evidence indicates that lactate shuttling coupled to its local oxidation during activation is a small fraction of glucose oxidation. Developmental, experimental, and physiological context is critical for interpretation of metabolic studies in terms of theoretical models.
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43
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Duarte JMN, Gruetter R. Characterization of cerebral glucose dynamics in vivo with a four-state conformational model of transport at the blood-brain barrier. J Neurochem 2012; 121:396-406. [DOI: 10.1111/j.1471-4159.2012.07688.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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44
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Shestov AA, Emir UE, Kumar A, Henry PG, Seaquist ER, Öz G. Simultaneous measurement of glucose transport and utilization in the human brain. Am J Physiol Endocrinol Metab 2011; 301:E1040-9. [PMID: 21791622 PMCID: PMC3213999 DOI: 10.1152/ajpendo.00110.2011] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Glucose is the primary fuel for brain function, and determining the kinetics of cerebral glucose transport and utilization is critical for quantifying cerebral energy metabolism. The kinetic parameters of cerebral glucose transport, K(M)(t) and V(max)(t), in humans have so far been obtained by measuring steady-state brain glucose levels by proton ((1)H) NMR as a function of plasma glucose levels and fitting steady-state models to these data. Extraction of the kinetic parameters for cerebral glucose transport necessitated assuming a constant cerebral metabolic rate of glucose (CMR(glc)) obtained from other tracer studies, such as (13)C NMR. Here we present new methodology to simultaneously obtain kinetic parameters for glucose transport and utilization in the human brain by fitting both dynamic and steady-state (1)H NMR data with a reversible, non-steady-state Michaelis-Menten model. Dynamic data were obtained by measuring brain and plasma glucose time courses during glucose infusions to raise and maintain plasma concentration at ∼17 mmol/l for ∼2 h in five healthy volunteers. Steady-state brain vs. plasma glucose concentrations were taken from literature and the steady-state portions of data from the five volunteers. In addition to providing simultaneous measurements of glucose transport and utilization and obviating assumptions for constant CMR(glc), this methodology does not necessitate infusions of expensive or radioactive tracers. Using this new methodology, we found that the maximum transport capacity for glucose through the blood-brain barrier was nearly twofold higher than maximum cerebral glucose utilization. The glucose transport and utilization parameters were consistent with previously published values for human brain.
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Affiliation(s)
- Alexander A Shestov
- Center for Magnetic Resonance Research, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
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Rothman DL, De Feyter HM, de Graaf RA, Mason GF, Behar KL. 13C MRS studies of neuroenergetics and neurotransmitter cycling in humans. NMR IN BIOMEDICINE 2011; 24:943-57. [PMID: 21882281 PMCID: PMC3651027 DOI: 10.1002/nbm.1772] [Citation(s) in RCA: 187] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 06/09/2011] [Accepted: 06/14/2011] [Indexed: 05/05/2023]
Abstract
In the last 25 years, (13)C MRS has been established as the only noninvasive method for the measurement of glutamate neurotransmission and cell-specific neuroenergetics. Although technically and experimentally challenging, (13)C MRS has already provided important new information on the relationship between neuroenergetics and neuronal function, the energy cost of brain function, the high neuronal activity in the resting brain state and how neuroenergetics and neurotransmitter cycling are altered in neurological and psychiatric disease. In this article, the current state of (13)C MRS as it is applied to the study of neuroenergetics and neurotransmitter cycling in humans is reviewed. The focus is predominantly on recent findings in humans regarding metabolic pathways, applications to clinical research and the technical status of the method. Results from in vivo (13)C MRS studies in animals are discussed from the standpoint of the validation of MRS measurements of neuroenergetics and neurotransmitter cycling, and where they have helped to identify key questions to address in human research. Controversies concerning the relationship between neuroenergetics and neurotransmitter cycling and factors having an impact on the accurate determination of fluxes through mathematical modeling are addressed. We further touch upon different (13)C-labeled substrates used to study brain metabolism, before reviewing a number of human brain diseases investigated using (13)C MRS. Future technological developments are discussed that will help to overcome the limitations of (13)C MRS, with special attention given to recent developments in hyperpolarized (13)C MRS.
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Affiliation(s)
- Douglas L Rothman
- Department of Diagnostic Radiology, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, CT 06520-8043, USA.
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Hackett MJ, McQuillan JA, El-Assaad F, Aitken JB, Levina A, Cohen DD, Siegele R, Carter EA, Grau GE, Hunt NH, Lay PA. Chemical alterations to murine brain tissue induced by formalin fixation: implications for biospectroscopic imaging and mapping studies of disease pathogenesis. Analyst 2011; 136:2941-52. [DOI: 10.1039/c0an00269k] [Citation(s) in RCA: 143] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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The contribution of blood lactate to brain energy metabolism in humans measured by dynamic 13C nuclear magnetic resonance spectroscopy. J Neurosci 2010; 30:13983-91. [PMID: 20962220 DOI: 10.1523/jneurosci.2040-10.2010] [Citation(s) in RCA: 240] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
To determine whether plasma lactate can be a significant fuel for human brain energy metabolism, infusions of [3-(13)C]lactate and (1)H-(13)C polarization transfer spectroscopy were used to detect the entry and utilization of lactate. During the 2 h infusion study, (13)C incorporation in the amino acid pools of glutamate and glutamine were measured with a 5 min time resolution. With a plasma concentration ([Lac](P)) being in the 0.8-2.8 mmol/L range, the tissue lactate concentration ([Lac](B)) was assessed as well as the fractional contribution of lactate to brain energy metabolism (CMRlac). From the measured relationship between unidirectional lactate influx (V(in)) and plasma and brain lactate concentrations, lactate transport constants were calculated using a reversible Michaelis-Menten model. The results show that (1) in the physiological range, plasma lactate unidirectional transport (V(in)) and concentration in tissue increase close to linearly with the lactate concentration in plasma; (2) the maximum potential contribution of plasma lactate to brain metabolism is 10% under basal plasma lactate conditions of ∼1.0 mmol/L and as much as 60% at supraphysiological plasma lactate concentrations when the transporters are saturated; (3) the half-saturation constant K(T) is 5.1 ± 2.7 mmol/L and V(MAX) is 0.40 ± 0.13 μmol · g(-1) · min(-1) (68% confidence interval); and (4) the majority of plasma lactate is metabolized in neurons similar to glucose.
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48
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Patel AB, de Graaf RA, Rothman DL, Behar KL, Mason GF. Evaluation of cerebral acetate transport and metabolic rates in the rat brain in vivo using 1H-[13C]-NMR. J Cereb Blood Flow Metab 2010; 30:1200-13. [PMID: 20125180 PMCID: PMC2879471 DOI: 10.1038/jcbfm.2010.2] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Acetate is a well-known astrocyte-specific substrate that has been used extensively to probe astrocytic function in vitro and in vivo. Analysis of amino acid turnover curves from (13)C-acetate has been limited mainly for estimation of first-order rate constants from exponential fitting or calculation of relative rates from steady-state (13)C enrichments. In this study, we used (1)H-[(13)C]-Nuclear Magnetic Resonance spectroscopy with intravenous infusion of [2-(13)C]acetate-Na(+) in vivo to measure the cerebral kinetics of acetate transport and utilization in anesthetized rats. Kinetics were assessed using a two-compartment (neuron/astrocyte) analysis of the (13)C turnover curves of glutamate-C4 and glutamine-C4 from [2-(13)C]acetate-Na(+), brain acetate levels, and the dependence of steady-state glutamine-C4 enrichment on blood acetate levels. The steady-state enrichment of glutamine-C4 increased with blood acetate concentration until 90% of plateau for plasma acetate of 4 to 5 mmol/L. Analysis assuming reversible, symmetric Michaelis-Menten kinetics for transport yielded 27+/-2 mmol/L and 1.3+/-0.3 micromol/g/min for K(t) and T(max), respectively, and for utilization, 0.17+/-0.24 mmol/L and 0.14+/-0.02 micromol/g/min for K(M_util) and V(max_util), respectively. The distribution space for acetate was only 0.32+/-0.12 mL/g, indicative of a large excluded volume. The astrocytic and neuronal tricarboxylic acid cycle fluxes were 0.37+/-0.03 micromol/g/min and 1.41+/-0.11 micromol/g/min, respectively; astrocytes thus comprised approximately 21%+/-3% of total oxidative metabolism.
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Affiliation(s)
- Anant B Patel
- Department of Diagnostic Radiology, Magnetic Resonance Research Center, Yale University School of Medicine, New Haven, Connecticut, USA.
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49
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Heikkilä O, Lundbom N, Timonen M, Groop PH, Heikkinen S, Mäkimattila S. Evidence for abnormal glucose uptake or metabolism in thalamus during acute hyperglycaemia in type 1 diabetes--a 1H MRS study. Metab Brain Dis 2010; 25:227-34. [PMID: 20424902 DOI: 10.1007/s11011-010-9199-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/25/2009] [Accepted: 01/15/2010] [Indexed: 11/24/2022]
Abstract
Acute hyperglycaemia impairs cognitive function. It is however not known, whether different brain regions are equally exposed to glucose during acute hyperglycemia or whether the brain is able to adjust its glucose uptake or metabolism in response to blood glucose fluctuation. We studied the effect of acute hyperglycaemia on the brain glucose concentration in seven men with type 1 diabetes with daily glucose fluctuations of 11 +/- 3 mmol/l, and in eleven age-matched non-diabetic men. Glucose was quantified with proton magnetic resonance spectroscopy in three different brain regions at baseline (fasting glycaemia) and twice during a 2 h hyperglycaemic clamp with plasma glucose increase of 12 mmol/l. The increase in brain glucose during acute hyperglycaemia in the non-diabetic group was: cortex (2.7 +/- 0.9 mmol/l) > thalamus (2.3 +/- 0.7 mmol/l) > white matter (1.7 +/- 0.7 mmol/l, P = 0.021 vs. cortex) and in the diabetic group: cortex (2.0 +/- 0.7 mmol/l) > white matter (1.3 +/- 0.7 mmol/l) > thalamus (1.1 +/- 0.4 mmol/l, P = 0.010 vs. cortex). In the diabetic group, the glucose increase in the thalamus was attenuated compared to the non-diabetic participants (P = 0.011). In conclusion, the increase of glucose during acute hyperglycaemia seems to be dependent on the brain tissue type. The high exposure of cortex to excess glucose and the altered glucose uptake or metabolism in the thalamus may thus contribute to hyperglycaemia related cognitive dysfunction.
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Affiliation(s)
- Outi Heikkilä
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Haarmaninkatu 8, Helsinki, Finland.
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Lei H, Duarte JMN, Mlynarik V, Python A, Gruetter R. Deep thiopental anesthesia alters steady-state glucose homeostasis but not the neurochemical profile of rat cortex. J Neurosci Res 2010; 88:413-9. [PMID: 19746430 DOI: 10.1002/jnr.22212] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Barbiturates are regularly used as an anesthetic for animal experimentation and clinical procedures and are frequently provided with solubilizing compounds, such as ethanol and propylene glycol, which have been reported to affect brain function and, in the case of (1)H NMR experiments, originate undesired resonances in spectra affecting the quantification. As an alternative, thiopental can be administrated without any solubilizing agents. The aim of the study was to investigate the effect of deep thiopental anesthesia on the neurochemical profile consisting of 19 metabolites and on glucose transport kinetics in vivo in rat cortex compared with alpha-chloralose using localized (1)H NMR spectroscopy. Thiopental was devoid of effects on the neurochemical profile, except for the elevated glucose at a given plasma glucose level resulting from thiopental-induced depression of glucose consumption at isoelectrical condition. Over the entire range of plasma glucose levels, steady-state glucose concentrations were increased on average by 48% +/- 8%, implying that an effect of deep thiopental anesthesia on the transport rate relative to cerebral glucose consumption ratio was increased by 47% +/- 8% compared with light alpha-chloralose-anesthetized rats. We conclude that the thiopental-induced isoelectrical condition in rat cortex significantly affected glucose contents by depressing brain metabolism, which remained substantial at isoelectricity.
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Affiliation(s)
- Hongxia Lei
- Laboratory of functional and metabolic imaging (LIFMET), Institute of the Physics of Biological Systems, Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
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