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Rao X, Hussain G, Huang Q, Chu WJ, Li N, Zhao X, Dun Z, Choi ES, Asaba T, Chen L, Li L, Yue XY, Wang NN, Cheng JG, Gao YH, Shen Y, Zhao J, Chen G, Zhou HD, Sun XF. Survival of itinerant excitations and quantum spin state transitions in YbMgGaO 4 with chemical disorder. Nat Commun 2021; 12:4949. [PMID: 34400621 PMCID: PMC8367942 DOI: 10.1038/s41467-021-25247-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [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: 09/02/2020] [Accepted: 07/01/2021] [Indexed: 11/16/2022] Open
Abstract
A recent focus of quantum spin liquid (QSL) studies is how disorder/randomness in a QSL candidate affects its true magnetic ground state. The ultimate question is whether the QSL survives disorder or the disorder leads to a “spin-liquid-like” state, such as the proposed random-singlet (RS) state. Since disorder is a standard feature of most QSL candidates, this question represents a major challenge for QSL candidates. YbMgGaO4, a triangular lattice antiferromagnet with effective spin-1/2 Yb3+ions, is an ideal system to address this question, since it shows no long-range magnetic ordering with Mg/Ga site disorder. Despite the intensive study, it remains unresolved as to whether YbMgGaO4 is a QSL or in the RS state. Here, through ultralow-temperature thermal conductivity and magnetic torque measurements, plus specific heat and DC magnetization data, we observed a residual κ0/T term and series of quantum spin state transitions in the zero temperature limit for YbMgGaO4. These observations strongly suggest that a QSL state with itinerant excitations and quantum spin fluctuations survives disorder in YbMgGaO4. It remains an open question as to whether the quantum spin liquid state survives material disorder, or is replaced by some spin-liquid like state. Here, Rao et al succeed in resolving a resolving a κ0/T residual in the thermal conductivity of YbMgGaO4 strongly suggesting the survival of the quantum spin liquid state.
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Affiliation(s)
- X Rao
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - G Hussain
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
| | - W J Chu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - N Li
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - X Zhao
- School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China
| | - Z Dun
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, USA
| | - T Asaba
- Department of Physics, University of Michigan, Ann Arbor, MI, USA
| | - L Chen
- Department of Physics, University of Michigan, Ann Arbor, MI, USA
| | - L Li
- Department of Physics, University of Michigan, Ann Arbor, MI, USA
| | - X Y Yue
- Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, People's Republic of China
| | - N N Wang
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - J-G Cheng
- Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China
| | - Y H Gao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China
| | - Y Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China
| | - J Zhao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China
| | - G Chen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, People's Republic of China. .,Department of Physics and HKU-UCAS Joint Institute for Theoretical and Computational Physics at Hong Kong, The University of Hong Kong, Hong Kong, China.
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA.
| | - X F Sun
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, Hefei, Anhui, People's Republic of China. .,Institute of Physical Science and Information Technology, Anhui University, Hefei, Anhui, People's Republic of China.
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Li N, Huang Q, Yue XY, Chu WJ, Chen Q, Choi ES, Zhao X, Zhou HD, Sun XF. Possible itinerant excitations and quantum spin state transitions in the effective spin-1/2 triangular-lattice antiferromagnet Na 2BaCo(PO 4) 2. Nat Commun 2020; 11:4216. [PMID: 32839456 PMCID: PMC7445251 DOI: 10.1038/s41467-020-18041-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [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: 12/01/2019] [Accepted: 08/03/2020] [Indexed: 11/09/2022] Open
Abstract
The most fascinating feature of certain two-dimensional (2D) gapless quantum spin liquid (QSL) is that their spinon excitations behave like the fermionic carriers of a paramagnetic metal. The spinon Fermi surface is then expected to produce a linear increase of the thermal conductivity with temperature that should manifest via a residual value (κ0/T) in the zero-temperature limit. However, this linear in T behavior has been reported for very few QSL candidates. Here, we studied the ultralow-temperature thermal conductivity of an effective spin-1/2 triangular QSL candidate Na2BaCo(PO4)2, which has an antiferromagnetic order at very low temperature (TN ~ 148 mK), and observed a finite κ0/T extrapolated from the data above TN. Moreover, while approaching zero temperature, it exhibits series of quantum spin state transitions with applied field along the c axis. These observations indicate that Na2BaCo(PO4)2 possibly behaves as a gapless QSL with itinerant spin excitations above TN and its strong quantum spin fluctuations persist below TN.
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Affiliation(s)
- N Li
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Q Huang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA
| | - X Y Yue
- Institute of Physical Science and Information Technology, Anhui University, 230601, Hefei, Anhui, People's Republic of China
| | - W J Chu
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - Q Chen
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA
| | - E S Choi
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310-3706, USA
| | - X Zhao
- School of Physical Sciences, University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China
| | - H D Zhou
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996-1200, USA.
| | - X F Sun
- Hefei National Laboratory for Physical Sciences at Microscale, Department of Physics, and Key Laboratory of Strongly-Coupled Quantum Matter Physics (CAS), University of Science and Technology of China, 230026, Hefei, Anhui, People's Republic of China. .,Institute of Physical Science and Information Technology, Anhui University, 230601, Hefei, Anhui, People's Republic of China.
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Chen HH, Tsai SL, You WR, Chen CJ, Chen PC, Lin MC, Chu WJ, Huang YT. Current status and outlook on the development of traditional Chinese medicine in Taiwan. J Formos Med Assoc 2018; 117:544-546. [PMID: 29625845 DOI: 10.1016/j.jfma.2018.03.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2017] [Revised: 03/20/2018] [Accepted: 03/21/2018] [Indexed: 06/08/2023] Open
Affiliation(s)
- Hui-Hsin Chen
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Su-Lin Tsai
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Wan-Ru You
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Chao-Jung Chen
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Ping-Chi Chen
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Mei-Chih Lin
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Wen-Jye Chu
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC
| | - Yi-Tsau Huang
- Department of Chinese Medicine and Pharmacy, Ministry of Health and Welfare, Taiwan, ROC; Institute of Traditional Medicine, School of Medicine, National Yang-Ming University, Taiwan, ROC.
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Chen WG, Shan H, Ye JM, Zhang PW, Jin KL, Lin K, Chu WJ. [Impact of carbon dioxide pneumoperitoneum in operating rooms on the health of medical staffs]. Zhonghua Lao Dong Wei Sheng Zhi Ye Bing Za Zhi 2017; 35:193-195. [PMID: 28511304 DOI: 10.3760/cma.j.issn.1001-9391.2017.03.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Objective: To evaluate the impact of CO(2) pneumoperitoneum in operating rooms on the health of medical staffs. Methods: In June 2016, the thirty-three medical staffs in operating rooms were chosen as the object of the research.Seventeen people who took part in the pneumoperitoneum operation were selected as a exposure group and sixteen people who took part in the laparotomy operation were selected as a control group.Vital signs and arterial blood gases of medical staffs in the two groups were both measured in pre-operation and post-operation. Occupational Health Questionnaires were conducted to collect information on age, weight and postoperative symptoms. The level of CO(2) in operating room was determined by a portable infrared CO(2) analyzer. Results: Compared with the control group, the concentration of CO(2) in the exposed group was higherat T(1), T(2) and T(3) (t=22.227, 13.583, 17.408, P<0.05) . Heart rates and PaCO(2) in the exposure group raised greatly (t=2.132, 2.129, P<0.05) , while pH decreased (t=-3.015, P<0.05) . The differences between the two groups were statistically significant. Conclusion: The increase of mild acidosis and thesense of job burnout in medical staffs could be caused by CO(2) pollution in the operating rooms.
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Affiliation(s)
- W G Chen
- Zhejiang Hospital, Hangzhou 310000, China
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Dodd CH, Hsu HC, Chu WJ, Yang P, Zhang HG, Mountz JD, Zinn K, Forder J, Josephson L, Weissleder R, Mountz JM, Mountz JD. Normal T-cell response and in vivo magnetic resonance imaging of T cells loaded with HIV transactivator-peptide-derived superparamagnetic nanoparticles. J Immunol Methods 2001; 256:89-105. [PMID: 11516758 DOI: 10.1016/s0022-1759(01)00433-1] [Citation(s) in RCA: 188] [Impact Index Per Article: 8.2] [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: 02/07/2023]
Abstract
The present study analyzed the feasibility of using magnetic resonance imaging (MRI) to monitor T-cell homing in vivo after loading T cells with superparamagnetic iron oxide (CLIO) nanoparticles derivatized with a peptide sequence from the transactivator protein (Tat) of HIV-1. T cells were isolated from C57BL/6 (B6) mice and loaded with 0, 400, 800, 1600, or 8000 ng/ml of FITC conjugated CLIO-Tat (FITC-CLIO-Tat). There was a dose-dependent uptake of FITC-CLIO-Tat by T cells. Stimulation of FITC-CLIO-Tat loaded T cells with anti-CD3 (0.1 microg/ml) plus IL-2 (5 ng/ml) elicited normal activation and activation-induced cell death (AICD) responses, and normal upregulation of CD69, ICAM-1 (CD54), L-selectin (CD62L), and Fas. The FITC-CLIO-Tat loaded T cells (3 x 10(7)) were transferred intravenously (i.v.) into B6 mice and the in vivo MRI of mice was acquired using a spin-echo pulse sequence at 4.7 T with a Bruker Biospec system. Homing of T cells into the spleen was observed by a decrease in MRI signal intensity within 1 h after the transfer, which remained decreased for 2-24 h after transfer. These homing data were confirmed by FACS analysis and biodistribution analysis using 125I-CLIO-Tat. Thus, T cells can be efficiently loaded with FITC-CLIO-Tat without interfering with their normal activation and AICD, or homing to the spleen, and the biodistribution of FITC-CLIO-Tat loaded T cells can be monitored in vivo over time by MRI.
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Affiliation(s)
- C H Dodd
- Division of Clinical Immunology and Rheumatology, Department of Medicine, The University of Alabama at Birmingham, 35294, USA
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Patton HK, Chu WJ, Hetherington HP, den Hollander J, Stewart KE, Raper JL, Shelton BJ, Benveniste EN, Benos DJ. Alkaline pH changes in the cerebellum of asymptomatic HIV-infected individuals. NMR Biomed 2001; 14:12-18. [PMID: 11252036 DOI: 10.1002/nbm.677] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Human immunodeficiency virus (HIV) infection of the brain causes a complex cascade of cellular events involving several different cell types that eventually leads to neuronal cell death and the manifestation of the AIDS-associated dementia complex (ADC). Upon autopsy HIV-infected individuals show lesions within subcortical regions of the brain, including the cerebellum. Previously we have demonstrated, in primary and cell culture models of rat and human astrocytes, a change in intracellular pH (pH(i)) due to increased Na(+)/H(+) exchange following exposure to inactivated virus or gp120, the major HIV envelope glycoprotein. To further investigate whether any such in vivo pH(i) changes occur in human brains subsequent to HIV infection, we measured the pH(i) of the cerebellum in eight HIV-positive individuals and nine healthy volunteers using (31)P magnetic resonance spectroscopy imaging (MRSI) at high field strength (4.1 T). The results showed a significant difference between the age-adjusted mean pH(i) in the cerebellum in control group and patient groups (7.11 +/- 0.03 vs 7.16 +/- 0.04), and further HIV-infected individuals displayed a significant increase in the number of cerebellar volume elements that were alkaline. We hypothesize that this propensity towards alterations in cerebellar pH(i) may portend later neurological involvement resulting from HIV infection.
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Affiliation(s)
- H K Patton
- Department of Physiology and Biophysics, University of Alabama at Birmingham, 1918 University Boulevard, Birmingham, AL 35294-0005, USA
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Chu WJ, Kuzniecky RI, Hugg JW, Abou-Khalil B, Gilliam F, Faught E, Hetherington HP. Statistically driven identification of focal metabolic abnormalities in temporal lobe epilepsy with corrections for tissue heterogeneity using 1H spectroscopic imaging. Magn Reson Med 2000; 43:359-67. [PMID: 10725878 DOI: 10.1002/(sici)1522-2594(200003)43:3<359::aid-mrm7>3.0.co;2-c] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [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: 11/09/2022]
Abstract
1H spectroscopic imaging of N-acetyl-aspartate, creatine, and choline has proven to be a sensitive indicator for the lateralization of seizure foci in temporal lobe epilepsy. Previous studies have used right-left comparisons to identify the epileptogenic tissue assuming that alterations due to the disease process outweigh the effects of tissue heterogeneity. To evaluate the effectiveness of tissue heterogeneity corrected analyses, we evaluated three criteria for lateralization of the seizure focus: 1) a statistically driven method adjusted for tissue composition, 2) a single valued threshold, and 3) a single global index of the hippocampus. The statistically driven analysis lateralized all eight patients correctly, whereas the single threshold method incorrectly lateralized one case and the global index failed to identify a significant difference in two cases. These findings indicate that increased accuracy and sensitivity can be obtained by correcting for tissue heterogeneity when analyzing spectroscopy studies of temporal lobe epilepsy.
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Affiliation(s)
- W J Chu
- Center for Nuclear Imaging Research, University of Alabama at Birmingham, USA
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Mason GF, Pan JW, Chu WJ, Newcomer BR, Zhang Y, Orr R, Hetherington HP. Measurement of the tricarboxylic acid cycle rate in human grey and white matter in vivo by 1H-[13C] magnetic resonance spectroscopy at 4.1T. J Cereb Blood Flow Metab 1999; 19:1179-88. [PMID: 10566964 DOI: 10.1097/00004647-199911000-00002] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
13C isotopic labeling data were obtained by 1H-observed/13C-edited magnetic resonance spectroscopy in the human brain in vivo and analyzed using a mathematical model to determine metabolic rates in human grey matter and white matter. 22.5-cc and 56-cc voxels were examined for grey matter and white matter, respectively. When partial volume effects were ignored, the measured tricarboxylic acid cycle rate was 0.72+/-0.22 (mean +/- SD) and 0.29+/-0.09 micromol min(-1) g(-1) (mean +/- SD) in voxels of approximately 70% grey and approximately 70% white matter, respectively. After correction for partial volume effects using a model with two tissue compartments, the tricarboxylic acid cycle rate in pure grey matter was higher (0.80+/-0.10 mol min(-1) g(-1); mean +/- SD) and in white matter was significantly lower (0.17+/-0.01 micromol min(-1) g(-1); mean +/- SD). In 1H-observed/13C-edited magnetic resonance spectroscopy labeling studies, the larger concentrations of labeled metabolites and faster metabolic rates in grey matter biased the measurements heavily toward grey matter, with labeling time courses in 70% grey matter appearing nearly identical to labeling in pure grey matter.
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Affiliation(s)
- G F Mason
- Department of Psychiatry, Yale University, New Haven, Connecticut, USA
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Abstract
PURPOSE To determine whether changes in the high-energy phosphates occur with use of the ketogenic diet in patients with intractable epilepsy. METHODS 31P magnetic resonance spectroscopic imaging studies were performed at 4.1 T in seven patients with intractable epilepsy (four Lennox-Gastaut syndrome, one absence, one primary generalized tonic-clonic, and one partial complex) before and after institution of the ketogenic diet. Coronal 1H anatomic imaging also was performed to provide correlation to the 31P data. RESULTS Taking the patients as a group, the ratio of phosphocreatine (PC)/gamma-adenosine triphosphate (ATP) measured at baseline (regular diet) compared with that measured after the ketogenic diet showed a small but significant increase from 0.61+/-0.08 to 0.69+/-0.08 (p < 0.05). Comparing the ratio of PCr inorganic phosphorus (Pi) measured at baseline with the postketogenic diet, there was a significant increase from 2.45+/-0.27 to 2.99+/-0.44 (p < 0.05). CONCLUSIONS As a group, improvement of energy metabolism occurs with use of the ketogenic diet. This is in agreement with the chronic ketosis studies performed earlier in rodents.
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Affiliation(s)
- J W Pan
- Medical Department, Brookhaven National Laboratory, Upton, New York 11793, USA
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Chu WJ, Hetherington HP, Kuzniecky RI, Simor T, Mason GF, Elgavish GA. Lateralization of human temporal lobe epilepsy by 31P NMR spectroscopic imaging at 4.1 T. Neurology 1998; 51:472-9. [PMID: 9710021 DOI: 10.1212/wnl.51.2.472] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [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: 11/15/2022] Open
Abstract
OBJECTIVE To compare the phosphorous metabolite ratios in the mesial temporal lobe of healthy volunteers (n = 20) with the corresponding ratios in patients with temporal lobe epilepsy (n = 30) using 31P NMR spectroscopic imaging and to lateralize the seizure focus in temporal lobe epilepsy patients using various phosphorous metabolite ratios-phosphocreatine to inorganic phosphate (PCr/Pi), PCr to adenosine triphosphate (PCr/gamma-ATP), and (gamma-ATP/Pi)--and to compare with clinical lateralization results. METHODS All 31P NMR spectroscopic imaging studies were performed on a high-field, 4.1 T, whole-body NMR spectroscopic imaging system using a 31P/1H double-tuned volume coil. RESULTS We found an average reduction of 15% in the PCr/Pi and gamma-ATP/Pi ratios compared with the corresponding ratios in healthy volunteers in the entire mesial temporal lobe, and more than a 30% reduction in these two ratios in the anterior region of the epileptogenic mesial temporal lobe. These ratios were also reduced significantly in the ipsilateral lobe when compared with their corresponding values in the contralateral lobe. In patients we lateralized the seizure focus, based on these 31P NMR data, and compared the results with the clinical lateralization. The lateralization based on either the PCr/Pi or the gamma-ATP/Pi ratio yielded a correspondence of 70 to 73% with the final clinical lateralization. In the subgroup of patients (n = 9) that needed intracranial EEG for the presurgical lateralization because of inconclusive results from the noninvasive methods, a 78% correspondence was found with the 31P NMR-based lateralization, whereas MRI provided a correspondence of only 33%, and scalp EEG provided a correspondence of only 56%. CONCLUSIONS These results suggest the utility of adding the 31P NMR method to the group of noninvasive modalities used for presurgical decision making in temporal lobe epilepsy patients.
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Affiliation(s)
- W J Chu
- Center for NMR Research and Development, University of Alabama at Birmingham, 35294-0006, USA
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Mason GF, Chu WJ, Vaughan JT, Ponder SL, Twieg DB, Adams D, Hetherington HP. Evaluation of 31P metabolite differences in human cerebral gray and white matter. Magn Reson Med 1998; 39:346-53. [PMID: 9498589 DOI: 10.1002/mrm.1910390303] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [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: 11/07/2022]
Abstract
31P NMR is commonly used to study brain energetics in health and disease. Due to sensitivity constraints, the NMR measurements are typically made in volumes that do not contain pure gray or white matter. For accurate evaluation of abnormalities in brain metabolite levels, it is necessary to consider the differences in normal levels of 31P metabolites in gray and white matter. In this study, voxels from a three-dimensional spectroscopic image acquisition were analyzed for their dependence on tissue type to assess differences in metabolite levels between gray and white matter. Specifically, gray matter was found to have significantly higher ratios of phosphocreatine (PCr) to gamma-ATP and PCr to the total 31P metabolite signal, whereas pH and the ratio of PCr to inorganic phosphate (Pi) were found to differ insignificantly between gray and white matter. Thus, tissue type can be an important factor to consider for alterations in bioenergetics by 31P NMR spectroscopic studies of the brain.
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Affiliation(s)
- G F Mason
- Department of Medicine, Center for Nuclear Imaging Research, University of Alabama at Birmingham, USA
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Abstract
The advantages of performing spectroscopic studies at higher field strengths include increased SNR, improved spectral resolution for J-coupled resonances, and improvements in the selectivity of spectral editing schemes. By using pulse sequences that minimize the required echo time, refocus J-evolution, employ low peak B1 requiring pulses and take advantage of spectroscopic imaging methods, these advantages can also be utilized in clinical applications of spectroscopy at high field. In addition to the static measurements measurements of N-acetyl aspartate (NAA), creatine (CR) and choline (CH) which can be performed at 1.5 T, high resolution measurements of glutamate, glutamine, GABA and the incorporation of 13C labeled glucose into glutamate are possible with improved spatial and spectral resolution. These methods have been utilized in patients with seizure disorders and multiple sclerosis to identify, characterize and map the metabolic changes associated with these diseases and their treatment.
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Affiliation(s)
- H P Hetherington
- Department of Medicine, University of Alabama at Birmingham, AL 35294-4470, USA
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Mason GF, Chu WJ, Hetherington HP. A general approach to error estimation and optimized experiment design, applied to multislice imaging of T1 in human brain at 4.1 T. J Magn Reson 1997; 126:18-29. [PMID: 9177795 DOI: 10.1006/jmre.1997.1143] [Citation(s) in RCA: 23] [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] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In this report, a procedure to optimize inversion-recovery times, in order to minimize the uncertainty in the measured T1 from 2-point multislice images of the human brain at 4.1 T, is discussed. The 2-point, 40-slice measurement employed inversion-recovery delays chosen based on the minimization of noise-based uncertainties. For comparison of the measured T1 values and uncertainties, 10-point, 3-slice measurements were also acquired. The measured T1 values using the 2-point method were 814, 1361, and 3386 ms for white matter, gray matter, and cerebral spinal fluid, respectively, in agreement with the respective T1 values of 817, 1329, and 3320 ms obtained using the 10-point measurement. The 2-point, 40-slice method was used to determine the T1 in the cortical gray matter, cerebellar gray matter, caudate nucleus, cerebral peduncle, globus pallidus, colliculus, lenticular nucleus, base of the pons, substantia nigra, thalamus, white matter, corpus callosum, and internal capsule.
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Affiliation(s)
- G F Mason
- Department of Medicine, University of Alabama at Birmingham 35294-4470, USA
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Chu WJ, Simor T, Elgavish GA. In vivo characterization of Gd(BME-DTTA), a myocardial MRI contrast agent: tissue distribution of its MRI intensity enhancement, and its effect on heart function. NMR Biomed 1997; 10:87-92. [PMID: 9267866 DOI: 10.1002/(sici)1099-1492(199704)10:2<87::aid-nbm438>3.0.co;2-t] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
We have determined an LD50 of 0.56 +/- 0.05 mmol/kg for liposomal Gd(BME-DTTA) in mice and also shown that liposomal Gd(BME-DTTA) has no deleterious effects on heart rate, blood pressure, left ventricular force and AV conductance in ferret hearts in vivo at the magnetic resonance imaging (MRI)-effective dose of 0.05 mmol/kg body weight. In MRI images, a 1H signal intensity enhancement is observed in the following organs in decreasing order of the effect: heart approximately spleen > kidney > liver. This enhancement is stable for over 3 h in all organs. The results of 1H MRI and electron micrographs indicate that the lipophilic fatty acyl groups in the ligand BME structure and the particle sizes of liposomal Gd(BME-DTTA) are two important factors for tissue specificity of liposomal Gd(BME-DTTA) in the intensity enhancement. In vitro relaxivity of a liposomal Gd(BME-DTTA) sample, stored at 4 degrees C, remained stable for over 4 months of observation, but a significant decrease in relaxivity was observed in a sample stored at room temperature, most likely reflecting some deterioration in liposome chemistry.
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Affiliation(s)
- W J Chu
- Department of Medicine, University of Alabama at Birmingham 35294, USA
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Pan JW, Mason GF, Vaughan JT, Chu WJ, Zhang Y, Hetherington HP. 13C editing of glutamate in human brain using J-refocused coherence transfer spectroscopy at 4.1 T. Magn Reson Med 1997; 37:355-8. [PMID: 9055224 DOI: 10.1002/mrm.1910370308] [Citation(s) in RCA: 25] [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: 02/03/2023]
Abstract
The method of single quantum 13C editing is analyzed and implemented with water suppressed J-refocused coherence transfer spectroscopy. Analysis of the 13C inversion pulse demonstrates that it is optimally placed into the second echo of the J-refocused sequence. We have used this method to acquire 13C-edited spectra of glutamate from phantoms and in vivo. The turnover of 13C4-labeled glutamate in human brain in vivo was observed in parasagittal gray matter using a volume head coil at 4.1 T with a time resolution of 5.3 min.
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Affiliation(s)
- J W Pan
- Department of Neurology, University of Alabama at Birmingham 35294, USA
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Chu WJ, Hetherington HP, Kuzniecky RJ, Vaughan JT, Twieg DB, Faught RE, Gilliam FG, Hugg JW, Elgavish GA. Is the intracellular pH different from normal in the epileptic focus of patients with temporal lobe epilepsy? A 31P NMR study. Neurology 1996; 47:756-60. [PMID: 8797475 DOI: 10.1212/wnl.47.3.756] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [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: 02/02/2023] Open
Abstract
We performed in vivo 31P NMR spectroscopic studies of human brain on a 4.1 T whole-body NMR system. Based on a control group of 20 healthy volunteers, the normal pHi was 7.05 (SD, 0.06; SEM, 0.01) in the left temporal lobe and 7.04 (SD, 0.04; SEM, 0.01) in the right temporal lobe. We also studied a patient group consisting of 13 individuals with unilateral temporal lobe epilepsy. The mean pHi was 7.02 (SD, 0.04; SEM, 0.01) in the ipsilateral lobe and 7.02 (SD, 0.05; SEM, 0.01) in the contralateral lobe. These results clearly show that no statistically significant difference in pHi is observed between the two lobes, either in normal controls or in patients. Also, no significant pHi difference exists between the control group and the patient group. Lateralization in each of the 13 patients with unilateral epilepsy, based on their individual pHi difference between the ipsilateral lobe and contralateral lobe (delta pHi), showed that three patients were nondiagnostic cases because their delta pHis were not significantly different from zero (< or = 0.02), five patients showed small delta pHis consistent with their clinical lateralization, whereas the remaining five patients showed delta pHi-based lateralization opposite to the clinical findings. These results seem to indicate an essentially random distribution around delta pHi = 0 within a very small experimental error of +/-0.02 pH units. pHi obtained from eight different areas in each of the 13 unilateral patients also did not show any significantly nonzero delta pHi values. These results led to the conclusion that even at the excellent spectral resolution and reproducibility of the 4.1 T machine (typical SD of 0.05 pH units), no significant pHi effect, induced by temporal lobe epilepsy, could be detected. Therefore, in this study, delta pHi does not appear to be a clinically useful tool for the lateralization of epileptic foci in patients with temporal lobe epilepsy.
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Affiliation(s)
- W J Chu
- Department of Medicine, UAB Epilepsy Center, USA
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Simor T, Chu WJ, Johnson L, Safranko A, Doyle M, Pohost GM, Elgavish GA. In vivo MRI visualization of acute myocardial ischemia and reperfusion in ferrets by the persistent action of the contrast agent Gd (BME-DTTA). Circulation 1995; 92:3549-59. [PMID: 8521578 DOI: 10.1161/01.cir.92.12.3549] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [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: 01/31/2023]
Abstract
BACKGROUND Contrast agent-enhanced magnetic resonance imaging (MRI) has the potential to visualize myocardial ischemia. To date, however, no agent has been found that has a sustained effect that allows MRI detection for the entire duration of ischemia and reperfusion and thus is useful in conjunction with stress test MRI. In this article, we introduce the gadolinium complex of N3,N6-bis(2'-myrisotyloxyethyl)-1,8-dioxo-triethylene- tetraamine-N,N,N1,N1-tetraacetic acid [Gd(BME-DTTA)], an agent potentially useful for such a purpose. METHODS AND RESULTS Four protocols were carried out. ECG-triggered, partially T1-weighted, spin-echo MRI was used in protocols A through C. In protocol A, in nonischemic ferrets, 50 mumol/kg Gd(BME-DTTA) induced a 70 +/- 5% intensity enhancement lasting 3 hours. In protocol B, the left anterior descending coronary artery was occluded, and a 99mTc-sestamibi-induced autoradiographic contrast verified (r = .87, P < .01) a Gd(BME-DTTA)-induced (n = 5) or Gd(DTPA)-induced (n = 4) MRI contrast. In the Gd(BME-DTTA) group a sustained contrast and in the Gd(DTPA) group a short-lived contrast were observed. In protocol C (n = 11), during ischemia, a 31 +/- 3.3% (P < .02) contrast was evident between the ischemic and nonischemic myocardial regions. Upon reperfusion, a contrast of 19 +/- 3% (P < .05) and 13 +/- 4.5% (P < .05) persisted for 5 and 15 minutes, respectively. Beyond 15 minutes, the contrast continued to diminish gradually. Nonradioactive microspheres verified (r = .87, P < .05) ischemia and reperfusion in this model. In protocol D (n = 4), blood delta R1 data showed that the blood pool retained Gd(BME-DTTA) for the entire time frame of the experiment at high enough concentration to provide an appropriate wash-in effect during the initial contrast enhancement and during reperfusion. CONCLUSIONS This study demonstrates that Gd(BME-DTTA) induces a sustained MRI contrast between regions of normal versus ischemic myocardium, showing the potential of this agent for the diagnosis of ischemic heart disease in conjunction with stress tests.
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Affiliation(s)
- T Simor
- Department of Medicine, University of Alabama at Birmingham 35294-0006, USA
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Chu WJ, Elgavish GA. Gadolinium and dysprosium chelates of DTPA-amide-dextran: synthesis, 1H NMR relaxivity, and induced 23Na NMR shift. NMR Biomed 1995; 8:159-163. [PMID: 8771090 DOI: 10.1002/nbm.1940080404] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
In this study the conjugated macromolecular ligand, diethylenetriaminepentaacetic acid (DTPA)-amide-dextran, was synthesized by attaching DTPA to the dextran macromolecule (M(r) approximately 6000) by a covalent amide bond. Subsequently, DTPA-amide-dextran was complexed with either of the two lanthanide metal ions dysprosium (Dy) or gadolinium (Gd). The paramagnetic 23Na NMR shift induced by Dy(DTPA-amide-dextran) and the relaxivity (rho 1) induced by Gd(DTPA-amide-dextran) were characterized. Dy(DTPA-amide-dextran) induced a 25% larger 23Na NMR shift than that induced by Dy(DTPA). Neither the shift induced by Dy(DTPA-amide-dextran) nor the shift induced by Dy(DTPA) was affected by increasing levels of calcium ions in the solution. offDTPA-amide-dextran) exhibited an in vitro rho 1 of 8.4 (mM s)-1 at a 0.23 T magnetic field and 9.3 (mM s)-1 at a 0.47 T magnetic field, thus indicating a positive magnetic field dependence.
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Affiliation(s)
- W J Chu
- Department of Medicine, University of Alabama at Birmingham 35294, USA
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Simor T, Kim SK, Chu WJ, Pohost GM, Elgavish GA. A selective inversion recovery method for the improvement of 23Na NMR spectral resolution in isolated perfused rat hearts. NMR Biomed 1993; 6:201-208. [PMID: 8347454 DOI: 10.1002/nbm.1940060306] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Shift-reagent-aided 23Na NMR spectroscopy allows differentiation of the intracellular (Na(i)) and extracellular sodium (Na(o)) signals. The goal of the present study has been to develop a 23Na NMR spectroscopic method to minimize the intensity of the shift-reagent-shifted Na(o) signal and thus increase Na(i) resolution. This is achieved by a selective inversion recovery (SIR) method which enhances the resolution between the Na(i) and Na(o) peaks in shift-reagent-aided 23Na NMR spectroscopy. The application of SIR with Dy(TTHA), Tm(DOTP), or with low concentrations of Dy(PPP)2 results in both good spectral resolution and physiologically acceptable contractile function in the isolated, perfused rat heart model.
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Affiliation(s)
- T Simor
- Department of Medicine, University of Alabama, Birmingham 35294-0006
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Miller SK, Chu WJ, Pohost GM, Elgavish GA. Improvement of spectral resolution in shift-reagent-aided 23Na NMR spectroscopy in the isolated perfused rat heart system. Magn Reson Med 1991; 20:184-95. [PMID: 1775046 DOI: 10.1002/mrm.1910200203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [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: 12/28/2022]
Abstract
The level of intracellular sodium (Nai) is maintained at approximately 14 mM in healthy myocytes. When myocytes are damaged, Nai increases and therefore the level of Nai may be a means of evaluating myocardial cell integrity. A particularly useful method to monitor Nai levels is 23Na NMR spectroscopy. However, because of the isochronous nature of the extracellular sodium (Nao) and Nai NMR signals, paramagnetic lanthanide shift reagents (LSR), such as dysprosium triphosphate, Dy(PPP)7-(2), have been used to shift the Nao signal. This reveals the unshifted Nai signal and allows the NMR monitoring of Nai in isolated perfused hearts and other systems. A major shortcoming of this method (the "shift-only" method) is in the need to minimize the Nao signal by not submerging the perfused hearts in Na(+)-containing buffer. An equally undesirable alternative is the utilization of relatively high concentrations of LSR to shift a large Nao signal sufficiently to enable reasonable resolution and quantitation of Nai. We present here a method, the "shift-relaxation" method, which is a combination of using a mixture of Dy(PPP)7-(2), a shift reagent, and gadolinium triphosphate, Gd(PPP)7-(2), a relaxation agent, with data acquisition using an inversion-recovery (IR) pulse sequence. This combination allows differentiation between Nao and Nai by the difference in their respective T1 values in addition to the shift between them. With this technique we can selectively minimize the extracellular signal and therefore minimize the need for a large Dy-induced shift, as well as allow data acquisition on a heart submerged in Na(+)-containing perfusate. The resulting improved discrimination between Nai and Nao at relatively low levels of LSR should be helpful for ultimate in vivo applications and potential clinical applications, where a lower dose of LSR also means a decreased possibility of physiologically deleterious effects. Also included in this paper is a method for the quick determination of an accurate 180 degrees pulse which is required for the optimization of the IR method.
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Affiliation(s)
- S K Miller
- Department of Medicine, University of Alabama, Birmingham 35294
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