1
|
Platt T, Ladd ME, Paech D. 7 Tesla and Beyond: Advanced Methods and Clinical Applications in Magnetic Resonance Imaging. Invest Radiol 2021; 56:705-725. [PMID: 34510098 PMCID: PMC8505159 DOI: 10.1097/rli.0000000000000820] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Revised: 08/07/2021] [Accepted: 08/07/2021] [Indexed: 12/15/2022]
Abstract
ABSTRACT Ultrahigh magnetic fields offer significantly higher signal-to-noise ratio, and several magnetic resonance applications additionally benefit from a higher contrast-to-noise ratio, with static magnetic field strengths of B0 ≥ 7 T currently being referred to as ultrahigh fields (UHFs). The advantages of UHF can be used to resolve structures more precisely or to visualize physiological/pathophysiological effects that would be difficult or even impossible to detect at lower field strengths. However, with these advantages also come challenges, such as inhomogeneities applying standard radiofrequency excitation techniques, higher energy deposition in the human body, and enhanced B0 field inhomogeneities. The advantages but also the challenges of UHF as well as promising advanced methodological developments and clinical applications that particularly benefit from UHF are discussed in this review article.
Collapse
Affiliation(s)
- Tanja Platt
- From the Medical Physics in Radiology, German Cancer Research Center (DKFZ)
| | - Mark E. Ladd
- From the Medical Physics in Radiology, German Cancer Research Center (DKFZ)
- Faculty of Physics and Astronomy
- Faculty of Medicine, University of Heidelberg, Heidelberg
- Erwin L. Hahn Institute for MRI, University of Duisburg-Essen, Essen
| | - Daniel Paech
- Division of Radiology, German Cancer Research Center (DKFZ), Heidelberg
- Clinic for Neuroradiology, University of Bonn, Bonn, Germany
| |
Collapse
|
2
|
Peeters TH, van Uden MJ, Rijpma A, Scheenen TW, Heerschap A. 3D 31 P MR spectroscopic imaging of the human brain at 3 T with a 31 P receive array: An assessment of 1 H decoupling, T 1 relaxation times, 1 H- 31 P nuclear Overhauser effects and NAD . NMR Biomed 2021; 34:e4169. [PMID: 31518036 PMCID: PMC8244063 DOI: 10.1002/nbm.4169] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2019] [Revised: 07/12/2019] [Accepted: 07/29/2019] [Indexed: 05/02/2023]
Abstract
31 P MR spectroscopic imaging (MRSI) is a versatile technique to study phospholipid precursors and energy metabolism in the healthy and diseased human brain. However, mainly due to its low sensitivity, 31 P MRSI is currently limited to research purposes. To obtain 3D 31 P MRSI spectra with improved signal-to-noise ratio on clinical 3 T MR systems, we used a coil combination consisting of a dual-tuned birdcage transmit coil and a 31 P eight-channel phased-array receive insert. To further increase resolution and sensitivity we applied WALTZ4 1 H decoupling and continuous wave nuclear Overhauser effect (NOE) enhancement and acquired high-quality MRSI spectra with nominal voxel volumes of ~ 17.6 cm3 (effective voxel volume ~ 51 cm3 ) in a clinically relevant measurement time of ~ 13 minutes, without exceeding SAR limits. Steady-state NOE enhancements ranged from 15 ± 9% (γ-ATP) and 33 ± 3% (phosphocreatine) to 48 ± 11% (phosphoethanolamine). Because of these improvements, we resolved and detected all 31 P signals of metabolites that have also been reported for ultrahigh field strengths, including resonances for NAD+ , NADH and extracellular inorganic phosphate. T1 times of extracellular inorganic phosphate were longer than for intracellular inorganic phosphate (3.8 ± 1.4s vs 1.8 ± 0.65 seconds). A comparison of measured T1 relaxation times and NOE enhancements at 3 T with published values between 1.5 and 9.4 T indicates that T1 relaxation of 31 P metabolite spins in the human brain is dominated by dipolar relaxation for this field strength range. Even although intrinsic sensitivity is higher at ultrahigh fields, we demonstrate that at a clinical field strength of 3 T, similar 31 P MRSI information content can be obtained using a sophisticated coil design combined with 1 H decoupling and NOE enhancement.
Collapse
Affiliation(s)
- Tom H. Peeters
- Department of Radiology and Nuclear MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Mark J. van Uden
- Department of Radiology and Nuclear MedicineRadboud University Medical CenterNijmegenThe Netherlands
| | - Anne Rijpma
- Department of Geriatric MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Radboudumc Alzheimer Center, Donders Institute for Brain, Cognition and BehaviourRadboud University Medical CenterNijmegenThe Netherlands
| | - Tom W.J. Scheenen
- Department of Radiology and Nuclear MedicineRadboud University Medical CenterNijmegenThe Netherlands
- Erwin L. Hahn InstituteUniversity Hospital Duisburg‐EssenEssenGermany
| | - Arend Heerschap
- Department of Radiology and Nuclear MedicineRadboud University Medical CenterNijmegenThe Netherlands
| |
Collapse
|
3
|
Benabou S, Ruckebusch C, Sliwa M, Aviñó A, Eritja R, Gargallo R, de Juan A. Study of conformational transitions of i-motif DNA using time-resolved fluorescence and multivariate analysis methods. Nucleic Acids Res 2020; 47:6590-6605. [PMID: 31199873 PMCID: PMC6649798 DOI: 10.1093/nar/gkz522] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 05/24/2019] [Accepted: 06/03/2019] [Indexed: 12/27/2022] Open
Abstract
Recently, the presence of i-motif structures at C-rich sequences in human cells and their regulatory functions have been demonstrated. Despite numerous steady-state studies on i-motif at neutral and slightly acidic pH, the number and nature of conformation of this biological structure are still controversial. In this work, the fluorescence lifetime of labelled molecular beacon i-motif-forming DNA sequences at different pH values is studied. The influence of the nature of bases at the lateral loops and the presence of a Watson–Crick-stabilized hairpin are studied by means of time-correlated single-photon counting technique. This allows characterizing the existence of several conformers for which the fluorophore has lifetimes ranging from picosecond to nanosecond. The information on the existence of different i-motif structures at different pH values has been obtained by the combination of classical global decay fitting of fluorescence traces, which provides lifetimes associated with the events defined by the decay of each sequence and multivariate analysis, such as principal component analysis or multivariate curve resolution based on alternating least squares. Multivariate analysis, which is seldom used for this kind of data, was crucial to explore similarities and differences of behaviour amongst the different DNA sequences and to model the presence and identity of the conformations involved in the pH range of interest. The results point that, for i-motif, the intrachain contact formation and its dissociation show lifetimes ten times faster than for the open form of DNA sequences. They also highlight that the presence of more than one i-motif species for certain DNA sequences according to the length of the sequence and the composition of the bases in the lateral loop.
Collapse
Affiliation(s)
- Sanae Benabou
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
| | - Cyril Ruckebusch
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Michel Sliwa
- Univ. Lille, CNRS, UMR 8516 - LASIR - Laboratoire de Spectrochimie Infrarouge et Raman, F-59000 Lille, France
| | - Anna Aviñó
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Jordi Girona 18-26, E-08034 Barcelona, Spain
| | - Ramon Eritja
- Institute for Advanced Chemistry of Catalonia (IQAC), CSIC, Networking Center on Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Jordi Girona 18-26, E-08034 Barcelona, Spain
| | - Raimundo Gargallo
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
| | - Anna de Juan
- Department of Chemical Engineering and Analytical Chemistry, University of Barcelona, Martí i Franquès 1-11, E-08028 Barcelona, Spain
| |
Collapse
|
4
|
van Uden MJ, Peeters TH, Rijpma A, Rodgers CT, Heerschap A, Scheenen TWJ. An 8-channel receive array for improved 31 P MRSI of the whole brain at 3T. Magn Reson Med 2019; 82:825-832. [PMID: 30900352 PMCID: PMC6520216 DOI: 10.1002/mrm.27736] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2018] [Revised: 02/21/2019] [Accepted: 02/21/2019] [Indexed: 12/26/2022]
Abstract
PURPOSE To demonstrate a 1 H/31 P whole human brain volume coil configuration for 3 Tesla with separate 31 P transmit and receive components that maintains 1 H MRS performance and delivers optimal 31 P MRSI with 1 H decoupling. METHODS We developed an 8-channel 31 P receive array coil covering the head to be used as an insert for a commercial double-tuned 1 H/31 P birdcage transmit-receive coil. This retains the possibility of using low-power rectangular pulses for 1 H-decoupled 3D 31 P MRSI (nominal resolution 17.6 cm3 ; acquisition duration 13 min) but increases the SNR with the receive sensitivity of 31 P surface coils. The performance of the combined coil setup was evaluated by measuring 1 H and 31 P SNR with and without the 31 P receive array and by assessing the effect of the receive array on the transmit efficiencies of the birdcage coil. RESULTS Compared to the birdcage coil alone, the 31 P insert in combination with the birdcage achieved an average 31 P SNR gain of 1.4 ± 0.4 in a center partition of the brain. The insert did not cause losses in 1 H MRS performance and transmit efficiency, whereas for 31 P approximately 20% more power was needed to achieve the same γB1. CONCLUSION The new coil configuration allows 1 H MRSI and optimal 1 H-decoupled 3D 31 P MRSI, with increased SNR of the human brain without patient repositioning, for clinical and research purposes at 3 Tesla.
Collapse
Affiliation(s)
- Mark J van Uden
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Tom H Peeters
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Anne Rijpma
- Department of Geriatric Medicine, Radboud university medical center, Nijmegen, The Netherlands.,Radboudumc Alzheimer Center, Donders Institute for Brain, Cognition and Behaviour, Radboud university medical center, Nijmegen, The Netherlands
| | | | - Arend Heerschap
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands
| | - Tom W J Scheenen
- Department of Radiology and Nuclear Medicine, Radboud university medical center, Nijmegen, The Netherlands.,Erwin L. Hahn Institute, University Hospital Duisburg-Essen, Essen, Germany
| |
Collapse
|
5
|
Zamiri B, Mirceta M, Abu-Ghazalah R, Wold MS, Pearson CE, Macgregor RB. Stress-induced acidification may contribute to formation of unusual structures in C9orf72-repeats. Biochim Biophys Acta Gen Subj 2018; 1862:1482-1491. [PMID: 29550431 DOI: 10.1016/j.bbagen.2018.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Revised: 02/22/2018] [Accepted: 03/04/2018] [Indexed: 12/12/2022]
Abstract
BACKGROUND Expansion of the C9orf72 hexanucleotide repeat (GGGGCC)n·(GGCCCC)n is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Both strands of the C9orf72 repeat have been shown to form unusual DNA and RNA structures that are thought to be involved in mutagenesis and/or pathogenesis. We previously showed that the C-rich DNA strands from the C9orf72 repeat can form four-stranded quadruplexes at neutral pH. The cytosine residues become protonated under slightly acidic pH (pH 4.5-6.2), facilitating the formation of intercalated i-motif structures. METHODS Using CD spectroscopy, UV melting, and gel electrophoresis, we demonstrate a pH-induced structural transition of the C-rich DNA strand of the C9orf72 repeat at pHs reported to exist in living cells under stress, including during neurodegeneration and cancer. RESULTS We show that the repeats with lengths of 4, 6, and 8 units, form intercalated quadruplex i-motifs at low pH (pH < 5) and monomolecular hairpins and monomolecular quadruplexes under neutral-basic conditions (pH ≥ 8). Furthermore, we show that the human replication protein A (RPA) binds to the G-rich and C-rich DNA strands under acidic conditions, suggesting that it can bind to i-motif structures. CONCLUSIONS In the proper sequence context, i-motif structures can form at pH values found in some cells in vivo. GENERAL SIGNIFICANCE DNA conformational plasticity exists over broad range of solution conditions.
Collapse
Affiliation(s)
- Bita Zamiri
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada
| | - Mila Mirceta
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada; Program of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A1, Canada
| | - Rashid Abu-Ghazalah
- W. Booth School of Engineering Technology Practice and Technology, McMaster University, Hamilton, Ontario L8S 0A3, Canada
| | - Marc S Wold
- Department of Biochemistry, Carver College of Medicine, University of Iowa, Iowa City, IA 52242, USA
| | - Christopher E Pearson
- Program of Genetics & Genome Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1L7, Canada; Program of Molecular Genetics, University of Toronto, Toronto, Ontario M5S 1A1, Canada
| | - Robert B Macgregor
- Graduate Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario M5S 3M2, Canada.
| |
Collapse
|
6
|
Park EJ, Otaduy MCG, Lyra KPD, Andrade CS, Castro LHM, Passarelli V, Valerio RMF, Jorge CL, Tsunemi MH, Leite CDC. Extratemporal abnormalities in phosphorus magnetic resonance spectroscopy of patients with mesial temporal sclerosis. Arq Neuro-Psiquiatr 2016; 74:93-8. [DOI: 10.1590/0004-282x20160005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Accepted: 10/26/2015] [Indexed: 11/22/2022]
Abstract
ABSTRACT Objective We evaluated extratemporal metabolic changes with phosphorus magnetic resonance spectroscopy (31P-MRS) in patients with unilateral mesial temporal sclerosis (MTS). Method 31P-MRS of 33 patients with unilateral MTS was compared with 31 controls. The voxels were selected in the anterior, posterior insula-basal ganglia (AIBG, PIBG) and frontal lobes (FL). Relative values of phosphodiesters- PDE, phosphomonoesters-PME, inorganic phosphate - Pi, phosphocreatine- PCr, total adenosine triphosphate [ATPt = γ- + a- + b-ATP] and the ratios PCr/ATPt, PCr/γ-ATP, PCr/Pi and PME/PDE were obtained. Results We found energetic abnormalities in the MTS patients compared to the controls with Pi reduction bilaterally in the AIBG and ipsilaterally in the PIBG and the contralateral FL; there was also decreased PCr/γ-ATP in the ipsilateral AIBG and PIBG. Increased ATPT in the contralateral AIBG and increased γ-ATP in the ipsilateral PIBG were detected. Conclusion Widespread energy dysfunction was detected in patients with unilateral MTS.
Collapse
|
7
|
Cichocka M, Kozub J, Urbanik A. PH Measurements of the Brain Using Phosphorus Magnetic Resonance Spectroscopy ((31)PMRS) in Healthy Men - Comparison of Two Analysis Methods. Pol J Radiol 2015; 80:509-14. [PMID: 26692912 PMCID: PMC4659444 DOI: 10.12659/pjr.895178] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Accepted: 07/21/2015] [Indexed: 11/29/2022] Open
Abstract
Background Intracellular pH provides information on homeostatic mechanisms in neurons and glial cells. The aim of this study was to define pH of the brain of male volunteers using phosphorus magnetic resonance spectroscopy (31PMRS) and to compare two methods of calculating this value. Material/Methods In this study, 35 healthy, young, male volunteers (mean age: 25 years) were examined by 31PMRS in 1.5 T MR system (Signa Excite, GE). The FID CSI (Free Induction Decay Chemical Shift Imaging) sequence was used with the following parameters: TR=4000 ms, FA=90°, NEX=2. Volume of interest (VOI) was selected depending on the size of the volunteers’ brain (11–14 cm3, mean 11.53 cm3). Raw data were analyzed using SAGE (GE) software. Results Based on the chemical shift of peaks in the 31PMRS spectrum, intracellular pH was calculated using two equations. In both methods the mean pH was slightly alkaline (7.07 and 7.08). Results were compared with a t-test. Significant difference (p<0.05) was found between these two methods. Conclusions The 31PMRS method enables non-invasive in vivo measurements of pH. The choice of the calculation method is crucial for computing this value. Comparing the results obtained by different teams can be done in a fully credible way only if the calculations were performed using the same formula.
Collapse
Affiliation(s)
- Monika Cichocka
- Department of Radiology, Collegium Medicum, Jagiellonian University, Cracow, Poland
| | - Justyna Kozub
- Department of Radiology, Collegium Medicum, Jagiellonian University, Cracow, Poland
| | - Andrzej Urbanik
- Department of Radiology, Collegium Medicum, Jagiellonian University, Cracow, Poland
| |
Collapse
|
8
|
|
9
|
Chaumeil MM, Valette J, Baligand C, Brouillet E, Hantraye P, Bloch G, Gaura V, Rialland A, Krystkowiak P, Verny C, Damier P, Remy P, Bachoud-Levi AC, Carlier P, Lebon V. pH as a biomarker of neurodegeneration in Huntington's disease: a translational rodent-human MRS study. J Cereb Blood Flow Metab 2012; 32:771-9. [PMID: 22373643 PMCID: PMC3345921 DOI: 10.1038/jcbfm.2012.15] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Early diagnosis and follow-up of neurodegenerative diseases are often hampered by the lack of reliable biomarkers. Neuroimaging techniques like magnetic resonance spectroscopy (MRS) offer promising tools to detect biochemical alterations at early stages of degeneration. Intracellular pH, which can be measured noninvasively by (31)P-MRS, has shown variations in several brain diseases. Our purpose has been to evaluate the potential of MRS-measured pH as a relevant biomarker of early degeneration in Huntington's disease (HD). We used a translational approach starting with a preclinical validation of our hypothesis before adapting the method to HD patients. (31)P-MRS-derived cerebral pH was first measured in rodents during chronic intoxication with 3-nitropropionic acid (3NP). A significant pH increase was observed early into the intoxication protocol (pH=7.17±0.02 after 3 days) as compared with preintoxication (pH=7.08±0.03). Furthermore, pH changes correlated with the 3NP-induced inhibition of succinate dehydrogenase and preceded striatum lesions. Using a similar MRS approach implemented on a clinical MRI, we then showed that cerebral pH was significantly higher in HD patients (n=7) than in healthy controls (n=6) (7.05±0.03 versus 7.02±0.01, respectively, P=0.026). Altogether, both preclinical and human data strongly argue in favor of MRS-measured pH being a promising biomarker for diagnosis and follow-up of HD.
Collapse
Affiliation(s)
- Myriam M Chaumeil
- 1] Commissariat à l'Energie Atomique, Institut d'Imagerie Biomédicale, Molecular Imaging Research Center, Centre National de la Recherche Scientifique, Unité de Recherche Associée, Fontenay-aux-Roses Cedex, France [2] Institut de Myologie, Laboratoire de RMN, Paris, France
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Andrade CS, Otaduy MCG, Valente KDR, Maia DF, Park EJ, Valério RMF, Tsunemi MH, Leite CC. Phosphorus magnetic resonance spectroscopy in malformations of cortical development. Epilepsia 2011; 52:2276-84. [PMID: 21973076 DOI: 10.1111/j.1528-1167.2011.03281.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
PURPOSE The aim of this study was to evaluate phospholipid metabolism in patients with malformations of cortical development (MCDs). METHODS Thirty-seven patients with MCDs and 31 control subjects were studied using three-dimensional phosphorus magnetic resonance spectroscopy ((31)P-MRS) at 3.0 T. The voxels in the lesions and in the frontoparietal cortex of the control subjects were compared (the effective volumes were 12.5 cm(3)). Robust quantification methods were applied to fit the time-domain data to the following resonances: phosphoethanolamine (PE); phosphocholine (PC); inorganic phosphate (Pi); glycerophosphoethanolamine (GPE); glycerophosphocholine (GPC); phosphocreatine (PCr); and α-, β-, and γ-adenosine triphosphate (ATP). We also estimated the total ATP (ATP(t) = α-+β-+γ-ATP), phosphodiesters (PDE = GPC+GPE), phosphomonoesters (PME = PE+PC), and the PME/PDE, PCr/ATP(t) and PCr/Pi ratios. The magnesium (Mg(2+)) levels and pH values were calculated based on PCr, Pi, and β-ATP chemical shifts. KEY FINDINGS Compared to controls and assuming that a p-value < 0.05 indicates statistical significance, the patients with MCDs exhibited significantly lower pH values and higher Mg(2+) levels. In addition, the patients with MCDs had lower GPC and PDE and an increased PME/PDE ratio. SIGNIFICANCE Mg(2+) and pH are important in the regulation of bioenergetics and are involved in many electrical activity pathways in the brain. Our data support the idea that neurometabolic impairments occur during seizure onset and propagation. The GPC, PDE, and PME/PDE abnormalities also demonstrate that there are membrane turnover disturbances in patients with MCDs.
Collapse
Affiliation(s)
- Celi S Andrade
- Department of Radiology, Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.
| | | | | | | | | | | | | | | |
Collapse
|
11
|
Bonnet U, Bingmann D, Wiltfang J, Scherbaum N, Wiemann M. Modulatory effects of neuropsychopharmaca on intracellular pH of hippocampal neurones in vitro. Br J Pharmacol 2009; 159:474-83. [PMID: 20015293 DOI: 10.1111/j.1476-5381.2009.00540.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
BACKGROUND AND PURPOSE The intracellular pH (pHi) of neurones is tightly regulated by, for example, membrane-bound acid-exchangers and loaders. Nevertheless, excessive bioelectric activity lowers steady-state pHi. In turn, even a moderate acidification can inhibit neuronal activity, a process believed to be part of a negative feedback loop controlling neuronal excitation. As moclobemide, an antidepressant, and also some antiepileptic drugs can reduce neuronal pHi in hippocampus slices in vitro, we screened a panel of currently used neuropsychopharmaca for comparable effects. EXPERIMENTAL APPROACH BCECF-AM loaded hippocampal slices were superfused with 16 different neuroleptics, antidepressants and antiepileptics under bicarbonate-buffered conditions. Changes in steady-state pHi of CA3 neurones were measured fluorometrically. KEY RESULTS The antipsychotics haloperidol, clozapine, ziprasidone, and the antidepressants amitriptyline, doxepin, trimipramine, citalopram, mirtazapine, as well as the anticonvulsive drug tiagabine reversibly reduced the steady-state pHi by up to 0.35 pH-units in concentrations of 5-50 microM. In contrast, venlafaxine, the anticonvulsants carbamazepine, clonazepam, gabapentin, lamotrigine, zonisamide, and the mood stabilizer lithium had no effect on neuronal pHi. CONCLUSION AND IMPLICATIONS These data substantiate the view that clinically relevant concentrations of neuroleptics and antidepressants can mediate changes in neuronal pHi, which may contribute to their pharmacological mode of action. Effects on pHi should be taken into account when therapeutic or even harmful effects of these drugs are evaluated.
Collapse
Affiliation(s)
- Udo Bonnet
- Department of Psychiatry and Psychotherapy, LVR-Hospital of Essen, University of Duisburg/Essen, Essen, Germany.
| | | | | | | | | |
Collapse
|
12
|
Gomes WA, Lado FA, de Lanerolle NC, Takahashi K, Pan C, Hetherington HP. Spectroscopic imaging of the pilocarpine model of human epilepsy suggests that early NAA reduction predicts epilepsy. Magn Reson Med 2007; 58:230-5. [PMID: 17654595 DOI: 10.1002/mrm.21310] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Reduced hippocampal N-acetyl aspartate (NAA) is commonly observed in patients with advanced, chronic temporal lobe epilepsy (TLE). It is unclear, however, whether an NAA deficit is also present during the clinically quiescent latent period that characterizes early TLE. This question has important implications for the use of MR spectroscopic imaging (MRSI) in the early identification of patients at risk for TLE. To determine whether NAA is diminished during the latent period, we obtained high-resolution (1)H spectroscopic imaging during the latent period of the rat pilocarpine model of human TLE. We used actively detuneable surface reception and volume transmission coils to enhance sensitivity and a semiautomated voxel shifting method to accurately position voxels within the hippocampi. During the latent period, 2 and 7 d following pilocarpine treatment, hippocampal NAA was significantly reduced by 27.5 +/- 6.9% (P < 0.001) and 17.3 +/- 6.9% (P < 0.001) at 2 and 7 d, respectively. Quantitative estimates of neuronal loss at 7 d (2.3 +/- 7.7% reduction; P = 0.58, not significant) demonstrate that the NAA deficit is not due to neuron loss and therefore likely represents metabolic impairment of hippocampal neurons during the latent phase. Therefore, spectroscopic imaging provides an early marker for metabolic dysfunction in this model of TLE.
Collapse
Affiliation(s)
- W A Gomes
- Department of Radiology, Montefiore Medical Center, Bronx, New York 10467, USA.
| | | | | | | | | | | |
Collapse
|
13
|
Abstract
Apoptosis plays an important role in cancer. Mechanisms hindering its action are implicated in a number of malignancies. Also, the induction of apoptosis plays a pivotal role in non-surgical cancer treatment regimes such as irradiation, chemotherapy, or hormones. Recent advanced in imaging science have made it now possible for us to detect and visualize previously inaccessible and even unrecognized biological phenomena in cells and tissue undergoing apoptosis in vivo. Not only are these imaging techniques painting an intriguing picture of the spatiotemporal characteristics and metabolic and biophysical of apoptosis in situ, but they are expected to have an ever increasing impact in preclinical testing and design of new anticancer agents as well. Rapid and accurate visualization of apoptotic response in the clinical settings can also be of significant diagnostic and prognostic worth. With the advent of molecular medicine and patient-tailored treatment options and therapeutic agents, such monitoring techniques are becoming paramount.
Collapse
Affiliation(s)
- Juhana M Hakumäki
- Cellular and Molecular Imaging Group, Department of Biomedical NMR, A.I. Virtanen Institute for Molecular Sciences, University of Kuopio, PO Box 1627, FI-70211 Kuopio, Finland.
| | | |
Collapse
|
14
|
Abstract
OBJECTIVES There is increasing evidence for a dysfunctional metabolic network in human mesial temporal lobe epilepsy (MTLE). To further describe this, we evaluated the bioenergetic status in unilateral MTLE inter-regionally and in relation to neuropathology. MATERIALS AND METHODS We used whole brain high field (4 T) 31P MR spectroscopic imaging to determine in vivo PCr and ATP, studying n=22 patients (all candidates for hippocampal resection) and n=14 control volunteers. The degree of bioenergetic impairment was assessed by calculating the ratio of PCr to ATP. RESULTS Compared to controls, patients demonstrated significant decreases in PCr/ATP from the ipsilateral amygdala and pes (0.84 +/- 0.14, 0.87 +/- 0.10, respectively, patients vs 0.97 +/- 0.15, 0.98 +/- 0.16, controls). In patients, the ipsilateral thalamic energetics positively correlated with contralateral hippocampal energetics. In addition, the ipsilateral thalamic and striatal energetics negatively correlated with hippocampal total glial counts. CONCLUSIONS These data are consistent with a view that in MTLE, the bilateral hippocampi, ipsilateral thalamus and striatum are linked in their energetic depression, possibly reflecting the propagation of seizures throughout the brain.
Collapse
Affiliation(s)
- J W Pan
- Department of Neurology, Albert Einstein College of Medicine, Bronx, NY 10461, USA.
| | | | | | | | | | | |
Collapse
|
15
|
Abstract
1H and 31P spectroscopy detects relevant metabolite changes in patients with TLE. Numerous studies confirm reduction in NAA and in the ratio of PCr/Pi. In his 1999 review, Kuzniecky concluded that proton MRS, using single-voxel or chemical shift imaging, lateralizes temporal lobe epilepsy in 65% to 96% of cases, with bilateral changes seen in 35% to 45% of cases, whereas phosphorus MRS shows a lateralizing PCr/Pi ratio in 65% to 75% of the TLE patients. There are indications that these changes are reversible with seizure treatment. Improvements in MRS technology, such as the ability to calculate absolute concentrations, to account for differences be-tween gray and white matter and to achieve better spectral resolution by use of a higher magnetic field strength, will now allow more extensive use of this technique for patients with epilepsy.
Collapse
Affiliation(s)
- Ruben Kuzniecky
- NYU Comprehensive Epilepsy Center, New York University School of Medicine, 403 East 34th Street, New York, NY 10016, USA.
| |
Collapse
|
16
|
Obata T, Someya Y, Suhara T, Ota Y, Hirakawa K, Ikehira H, Tanada S, Okubo Y. Neural damage due to temporal lobe epilepsy: dual-nuclei (proton and phosphorus) magnetic resonance spectroscopy study. Psychiatry Clin Neurosci 2004; 58:48-53. [PMID: 14678457 DOI: 10.1111/j.1440-1819.2004.01192.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aim of this study was to evaluate the usefulness of proton and phosphorus (1H and 31P) magnetic resonance spectroscopy (MRS) for temporal lobe epilepsy (TLE) patients, and to evaluate neural damage and metabolite dysfunction in the TLE patient brain. We performed 1H and 31P MRS of medial temporal lobes (MTL) in the same TLE patients (n = 14) with a relatively wide range of severity from almost seizure-free to intractable, and calculated the ratio of N-acetylasparate to choline-containing compounds and creatine + phosphocreatine (NAA/Cho + Cr) in 1H MRS and inorganic phosphate to all main peaks (%Pi) in 31P MRS. There was no significant correlation between NAA/(Cho + Cr) and %Pi in each side (ipsilateral, r = -0.20; contralateral, r =-0.19). The values of NAA/(Cho + Cr) showed a significant difference between ipsilateral and contralateral MTLs to the focus of TLE patients (P < 0.01, paired t-test). Although %Pi also had a tendency to show the laterality of TLE, there was no significance. Ipsilateral (r = -0.90, P < 0.0001) and contralateral (r = -0.70, P < 0.005) NAA/(Cho + Cr) decreases and contralateral %Pi increase (r = 0.81, P < 0.001) had significant correlation with seizure frequency. 1H MRS provides more important information concerning neuronal dysfunction in MTL of TLE patients than 31P MRS.
Collapse
Affiliation(s)
- Takayuki Obata
- Department of Medical Imaging, National Institute of Radiological Sciences, Chiba, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Vermathen P, Laxer KD, Schuff N, Matson GB, Weiner MW. Evidence of neuronal injury outside the medial temporal lobe in temporal lobe epilepsy: N-acetylaspartate concentration reductions detected with multisection proton MR spectroscopic imaging--initial experience. Radiology 2003; 226:195-202. [PMID: 12511690 PMCID: PMC2753262 DOI: 10.1148/radiol.2261011668] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To determine whether magnetic resonance (MR) spectroscopic imaging reveals metabolic changes, especially decreased N-acetylaspartate (NAA) concentrations outside the medial temporal lobe in patients with mesial temporal lobe epilepsy (TLE), consistent with neuropathologic findings of extratemporal neuronal impairment. MATERIALS AND METHODS Eleven patients with mesial TLE and 13 control subjects were examined with multisection MR spectroscopic imaging. Three MR spectroscopic imaging sections were acquired. Thirteen brain regions in each hemisphere and the midbrain were analyzed in each patient, and the NAA to creatine-phosphocreatine (Cr) plus choline-containing compounds (Ch) (NAA/[Cr + Ch]) ratios were determined. In addition, hemispheric and whole-brain values were calculated and statistically analyzed. RESULTS The NAA/(Cr + Ch) ratio in the ipsilateral hippocampus was significantly reduced, compared with that in the contralateral hippocampus (P <.002) and compared with that in control subjects (P <.03), confirming findings in previous studies. In patients, whole-brain NAA/(Cr + Ch) ratio outside the hippocampus was significantly lower than that in control subjects (P <.002). For the ipsilateral hemisphere in patients, NAA/(Cr + Ch) ratio was significantly lower than that in control subjects (P <.0002). Comparisons between individual brain regions revealed trends toward lower NAA/(Cr + Ch) ratios in many areas of the ipsilateral and, to a lesser extent, the contralateral hemisphere outside the hippocampus and temporal lobe, suggesting diffuse impairment. CONCLUSION Results suggest that repeated seizure activity damages neurons outside of the seizure focus.
Collapse
Affiliation(s)
- Peter Vermathen
- MR Unit, Department of Veterans Affairs Medical Center, University of California, San Francisco, USA.
| | | | | | | | | |
Collapse
|
18
|
Braun CMJ, Boulanger Y, Labelle M, Khiat A, Dumont M, Mailloux C. Brain metabolic differences as a function of hemisphere, writing hand preference, and gender. Laterality 2002; 7:97-113. [PMID: 15513191 DOI: 10.1080/13576500143000212] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
A total of 35 university-educated normal men (24 right handwriters and 11 left handwriters) and 36 age- and education-matched women (25 right handwriters and 11 left handwriters) underwent a proton magnetic resonance spectroscopy examination in seven 8 cm(3) voxels including the right and left frontal lobe tips, the right and left mid-temporal lobes, the right and left thalami, and the hypothalamus. Dependent measures were N-acetylaspartate (NAA), choline-containing compounds (Cho) and creatine/phosphocreatine (Cr) metabolite peak area ratios relative to total H(2)O. As expected, thalamic grey matter contained higher NAA ratios than telencephalic voxels (containing white and grey matter) (p < .001). The thalamic Cr/ H(2)O ratio was higher on the right, but the opposite asymmetry was observed for the temporal lobe (p < .05). Women had a higher left frontal NAA/ H(2)O ratio than men, but men had a higher hypothalamic NAA/ H(2)O ratio than women. Right-handers had a higher temporal lobe NAA/H(2)O ratio than left-handers, particularly in the left hemisphere. In addition, several significant 2- and 3-way interactions between writing hand preference, gender, and hemisphere were observed, but only in the frontal lobe.
Collapse
Affiliation(s)
- C M J Braun
- Centre de Neurosciences Cognitives, UQAM, Montréal, Québec, Canada.
| | | | | | | | | | | |
Collapse
|
19
|
Bonnet U, Leniger T, Wiemann M. Alteration of intracellular pH and activity of CA3-pyramidal cells in guinea pig hippocampal slices by inhibition of transmembrane acid extrusion. Brain Res 2000; 872:116-24. [PMID: 10924683 DOI: 10.1016/s0006-8993(00)02350-7] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Transmembrane acid extruders, such as electroneutral operating Na(+)/H(+)-exchangers (NHE) and Na(+)-dependent Cl(-)/HCO(3)(-)-exchangers (NCHE) are essential for the maintenance and regulation of cell volume and intracellular pH (pH(i)). Both of them are hypothesised to be closely linked to the control of excitability. To get further information about the relation of neuronal pH(i) and activity of cortical neurones we investigated the effect of NHE- and/or NCHE-inhibition on (i) spontaneous action potentials and epileptiform burst-activity (induced by bicuculline-methiodide, caffeine or 4-aminopyridine) and (ii) on pH(i) of CA3-neurones. NHE-inhibition by amiloride (0.25-0.5 mM) or its more potent derivative dimethylamiloride (50 microM) and NCHE-inhibition by 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS, 0.25-0.5 mM) induced a biphasic alteration of neuronal activity: an initial, up to 30 min lasting, increase in frequency of action potentials and bursts preceded a growing and partially reversible suppression of neuronal activity. In BCECF-loaded neurones the pH(i), however, continuously decreased during either amiloride- or DIDS-treatment and reached its steady-state (DeltapH(i) up to 0.3 pH-units) when the neuronal activity was markedly suppressed. Combined treatment with amiloride (0.5 mM) and DIDS (0.5 mM) or treatment with harmaline alone (0.25-0.5 mM), which also continuously acidified neurones via inhibition of an amiloride-insensitive NHE-subtype, induced a monophasic and partially reversible suppression of neuronal activity. As an initial excitatory period failed to occur during combined NHE/NCHE-inhibition we speculate that its occurrence during amiloride- or DIDS-treatment resulted rather from disturbances in volume- than in pH(i)-regulation. The powerful inhibitory and anticonvulsive properties of NHE- and NCHE-inhibitors, however, very likely based upon intracellular acidification - as derived from our previous findings that a moderate increase in intracellular free protons is sufficient to reduce membrane excitability of CA3-neurones.
Collapse
Affiliation(s)
- U Bonnet
- Rheinische Kliniken, Universitätsklinik für Psychiatrie und Psychotherapie, Universität-GH Essen, Virchowstr. 174, D-45147, Essen, Germany.
| | | | | |
Collapse
|