Abstract:
:Diffusion measurements were performed on the N-acetyl aspartate (NAA) signal in in situ brains (in vivo and post-mortem) and on in vitro brain tissue at 37 degrees C using wide ranges of b-values (from 0 up to 4.5 x 10(6) s/cm2 and 35.8 x 10(6) s/cm2 for the in vivo and the in vitro cases, respectively). In vivo and in vitro NAA signals attenuation due to diffusion was measured at fixed diffusion times (tD). In the in vitro cases the effect of tD on the apparent diffusion coefficients (ADCs) of NAA was evaluated. From these experiments the following observations and conclusions were made: (1) NAA signal attenuation both in vivo and in vitro is not mono-exponential and could be fitted by bi-exponential fitting function; (2) analysis of the low b-value range only (up to 0.5 x 10(6) s/cm2) gives a mono-exponential decay (r = 0.999); (3) in both cases the obtained ADCs are sensitive to the diffusion time; (4) the ADCs of the pre- and post-mortem cases are nearly similar; (5) the ADCs obtained from the bi-exponential fitting function decrease when the diffusion time increases; and (6) both the fast and the slow diffusing components of NAA show a considerable restriction by what seems to be a non-permeable barrier from which two compartments were identified, one having a size of 6-8 microns and the other of approximately 1-2 microns in size. It seems conceivable that the two populations identified in the diffusion experiments represent primarily the NAA in the cell body (soma) and in the neurital space (axons and proximal dendrites).
journal_name
NMR Biomedjournal_title
NMR in biomedicineauthors
Assaf Y,Cohen Ydoi
10.1002/(sici)1099-1492(199804)11:2<67::aid-nbm503subject
Has Abstractpub_date
1998-04-01 00:00:00pages
67-74issue
2eissn
0952-3480issn
1099-1492pii
10.1002/(SICI)1099-1492(199804)11:2<67::AID-NBM503journal_volume
11pub_type
杂志文章abstract::In this work we introduce the concept of correlation chemical shift imaging (CCSI). Novel CCSI pulse sequences are demonstrated on clinical scanners for two-dimensional Correlation Spectroscopy (COSY) and Total Correlation Spectroscopy (TOCSY) imaging experiments. To date there has been limited progress reported towar...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1730
更新日期:2012-02-01 00:00:00
abstract::1H NMR spin-echo spectroscopy has been used to study the metabolism of exogenous compounds in human erythrocytes. The non-invasive nature of the technique and the continuous monitoring makes it ideal to investigate both the conversion of substrates and the occurrence and the nature of the products. Hydrolysis rates ma...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1940030603
更新日期:1990-12-01 00:00:00
abstract::The phosphorus NMR spectra of isolated perfused rat liver displays a prominent inorganic phosphate peak at 2.76 +/- 0.05 ppm relative to liver glycerolphosphocholine at 0.49 ppm. From titration curves of phosphorus-containing compounds this corresponds to a pH of 7.4. The spectra also display a shoulder on the promine...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1940010207
更新日期:1988-04-01 00:00:00
abstract::Early imaging or blood biomarkers of tumor response is needed to customize anti-tumor therapy on an individual basis. This study evaluates the sensitivity and relevance of five potential MRI biomarkers. Sixty nude rats were implanted with human glioma cells (U-87 MG) and randomized into three groups: one group receive...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1611
更新日期:2011-06-01 00:00:00
abstract::Hyperglycemia (blood glucose concentration >150 mg/dL) is common in extremely low gestational age newborns (ELGANs; birth at <28 week gestation). Hyperglycemia increases the risk of brain injury in the neonatal period. The long-term effects are not well understood. In adult rats, hyperglycemia alters hippocampal energ...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.3910
更新日期:2018-05-01 00:00:00
abstract::Current functional MRI (fMRI) approaches assess underlying neuronal activity through monitoring the related local variations in cerebral blood oxygenation, blood volume and blood flow. This vascular response is likely to vary across brain regions and across individuals, depending on the composition of the local vascul...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.3282
更新日期:2015-05-01 00:00:00
abstract::Signal of lung parenchymal tissue from the living rat and mouse lung was detected at 4.7 T with a good signal-to-noise ratio and motion-suppressed artifacts using a short TE gradient-echo sequence. Neither cardiac nor respiratory gating were applied, and animals respired freely during data collection. Mean T(2)* relax...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.706
更新日期:2001-08-01 00:00:00
abstract::Under normal conditions, the heart mainly relies on fatty acid oxidation to meet its energy needs. Changes in myocardial fuel preference are noted in the diseased and failing heart. The magnetic resonance signal enhancement provided by spin hyperpolarization allows the metabolism of substrates labeled with carbon-13 t...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.4243
更新日期:2020-03-01 00:00:00
abstract::Two FDA-approved agents, ferumoxides (Feridex), a suspension of superparamagnetic iron oxide (SPIO) nanoparticles and protamine sulfate, a drug used to reverse heparin anticoagulation, can be complexed and used to label cells magnetically ex vivo. Labeling stem cells with ferumoxides-protamine sulfate (FePro) complexe...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.991
更新日期:2005-12-01 00:00:00
abstract::Normal subjects performed voluntary, isometric exercise 1 s contraction, 1 s rest for 10 min) of the first dorsal interosseous (FDI) muscle with a target force of 25, 50 and 100% of the maximal voluntary contraction (MVC) force. 31P NMR spectra were collected continuously before, during and after exercise. Data were a...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1940030504
更新日期:1990-10-01 00:00:00
abstract::The availability of high-field-strength magnetic resonance imaging (MRI) systems has brought about the development of techniques that aim to map myelination via the exploitation of various contrast mechanisms. Myelin mapping techniques have the potential to provide tools for the diagnosis and treatment of diseases, su...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.3877
更新日期:2018-03-01 00:00:00
abstract::d-amino acid oxidase (DAO) is a peroxisomal enzyme that catalyzes the oxidative deamination of several neutral and basic d-amino acids to their corresponding α-keto acids. In most mammalian species studied, high DAO activity is found in the kidney, liver, brain and polymorphonuclear leukocytes, and its main function i...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.4303
更新日期:2020-07-01 00:00:00
abstract::The physiological status of anesthetized rats greatly influences blood oxygenation level dependent (BOLD) functional magnetic resonance imaging (fMRI). Monitoring of physiological parameters, particularly partial pressure of carbon dioxide (pCO(2)) levels in the blood, is therefore an important part in the design and ...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.978
更新日期:2005-11-01 00:00:00
abstract::A short-echo spectroscopic imaging sequence extended with a frequency-selective multiple-quantum- coherence technique (Sel-MQC) is presented. The method enables acquisition of a complete water-suppressed proton spectrum with a short echo time and filtering of the J-coupling metabolite, lactate, from co-resonant lipids...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1284
更新日期:2008-11-01 00:00:00
abstract::Mice are used in many studies to determine the role of genetic and molecular factors in mammalian development and human congenital diseases. MRI has emerged as a major method for analyzing mutant and transgenic phenotypes in developing mice, at both embryonic and neonatal stages. Progress in this area is reviewed, wit...
journal_title:NMR in biomedicine
pub_type: 杂志文章,评审
doi:10.1002/nbm.1146
更新日期:2007-05-01 00:00:00
abstract::The reliability, relation to whole-body maximal oxygen uptake (VO(2max)), and force-level sensitivity of (31)P MRS markers of mitochondrial function were studied in 39 normal-weight women. Following 90 s isometric plantar-flexion exercises at 45, 70 and 100% of maximum voluntary contraction, skeletal muscle mitochondr...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/(sici)1099-1492(200002)13:1<14::aid-nbm605
更新日期:2000-01-01 00:00:00
abstract::Hyperpolarised (HP) (13)C NMR allows enzymatic activity to be probed in real time in live biological systems. The use of in vitro models gives excellent control of the cellular environment, crucial in the understanding of enzyme kinetics. The increased conversion of pyruvate to lactate in cancer cells has been well st...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.3341
更新日期:2015-08-01 00:00:00
abstract::Obesity causes damage to several organs, including the brain. Recent studies have been focusing on understanding the mechanisms through which obesity affects brain structure and function using neuroimaging techniques. A functional biomarker, such as cerebral blood flow (CBF), is a powerful tool that can be used to exp...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.4375
更新日期:2020-10-01 00:00:00
abstract::Brain myelin and iron content are important parameters in neurodegenerative diseases such as multiple sclerosis (MS). Both myelin and iron content influence the brain's R2* relaxation rate. However, their quantification based on R2* maps requires a realistic tissue model that can be fitted to the measured data. In str...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.4092
更新日期:2019-07-01 00:00:00
abstract::The application of diffusion tensor imaging (DTI) to the evaluation of developing brain remains an area of active investigation. This review focuses on the changes in DTI parameters which accompany both brain maturation and injury. The two primary pieces of information available from DTI studies-water apparent diffusi...
journal_title:NMR in biomedicine
pub_type: 杂志文章,评审
doi:10.1002/nbm.784
更新日期:2002-11-01 00:00:00
abstract::Natural abundance proton-decoupled (13)C magnetic resonance spectroscopy was used to establish the in vivo lipid composition of normal adipose tissue and the corresponding effects of altered lipid diets. Experiments were performed on a standard 1.5 T clinical MR scanner using a double-tuned (1)H-(13)C coil. Peaks from...
journal_title:NMR in biomedicine
pub_type: 临床试验,杂志文章
doi:10.1002/nbm.824
更新日期:2003-05-01 00:00:00
abstract::Aminoacylase 1 deficiency is a novel inborn error of metabolism. The clinical significance of the deficiency is under discussion, as well as the possible consequences of the defect for brain metabolism and function. This study includes the five originally published cases as well as three novel ones. NMR spectroscopy o...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1170
更新日期:2008-02-01 00:00:00
abstract::Given the importance of genetically modified mice in studies of mammalian brain development and human congenital brain diseases, MRI has the potential to provide an efficient in vivo approach for analyzing mutant phenotypes in the early postnatal mouse brain. The combination of reduced tissue contrast at the high magn...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.932
更新日期:2004-12-01 00:00:00
abstract::The aim of this work was to identify spectral markers of cell proliferation that could be of use in clinical MRS. Cultured C6 ATCC rat glioma cells were used as models for this purpose and metabolites were extracted with perchloric acid at three different growth curve stages: log, confluence and post-confluence. 1D an...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1024
更新日期:2006-04-01 00:00:00
abstract::Most ovarian tumors are cystic structures containing variable amounts of fluid. Several studies of ovarian cyst fluid focus on one specific metabolite using conventional assay systems. We examined the potential of (1)H-nuclear magnetic resonance spectroscopy in evaluation of the overall metabolic composition of cyst f...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/1099-1492(200008)13:5<297::aid-nbm648>3.0.
更新日期:2000-08-01 00:00:00
abstract:PURPOSE:To investigate the feasibility of using multiple flip angles in dynamic contrast enhanced (DCE) MRI to reduce the uncertainty in estimation of intracellular water lifetime (τi ). METHODS:Numerical simulation studies were conducted to assess the uncertainty in estimation of τi using dynamic contrast enhanced MR...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.4135
更新日期:2019-11-01 00:00:00
abstract::31P NMR spectra were obtained from sera of 22 healthy volunteers and 20 patients with multiple myeloma at the time of diagnosis and repeated up to five times during therapy. All spectra consisted of a Pi peak (used as a reference peak) and two peaks from phospholipids (PL): one peak due to phosphatidylethanolamine and...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1940080308
更新日期:1995-05-01 00:00:00
abstract::The present work aims to show the applicability of an analytical model for the optimisation of the STEAM sequence timing parameters for lactate detection at ultra high-field. The effects of the chemical shift displacement artefact on the J-modulated signal for a weakly-coupled spin system were considered in the three ...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.4440
更新日期:2020-11-02 00:00:00
abstract::A quantitative magnetization transfer (qMT) technique was employed to quantify the ratio of the sizes of the bound and free water proton pools in ex vivo mouse brains. The goal was to determine the pool size ratio sensitivity to myelin. Fixed brains from both shiverer mice and control littermates were imaged. The pool...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1358
更新日期:2009-06-01 00:00:00
abstract::Resolution enhancement for glutamate (Glu), glutamine (Gln) and glutathione (GSH) in the human brain by TE-optimized point-resolved spectroscopy (PRESS) at 7 T is reported. Sub-TE dependences of the multiplets of Glu, Gln, GSH, γ-aminobutyric acid (GABA) and N-acetylaspartate (NAA) at 2.2-2.6 ppm were investigated wit...
journal_title:NMR in biomedicine
pub_type: 杂志文章
doi:10.1002/nbm.1529
更新日期:2010-11-01 00:00:00