Absolute quantitation of glutamate, GABA and glutamine using localized 2D constant-time COSY spectroscopy in vivo.

Purpose: We propose an absolute quantitation method for metabolites with strongly coupled spin systems using localized 2-dimensional (2D) constant-time correlation spectroscopy (CT-COSY). We also develop two methods for improving the quality of in vivo CT-COSY spectra.

Methods: We substituted an image selected in vivo spectroscopy (ISIS) pulse for a 180° slice pulse in the CT-COSY module to decrease the slice displacement error caused by the chemical shift difference.

A Post-processing framework for localized 2D MR spectroscopy in vivo.

Purpose: We propose a post-processing framework for localized two-dimensional (2D) magnetic resonance spectroscopy (MRS) in vivo.

Methods: Our framework consists of corrections on eddy current and subject motion along with the framework used in conventional analytical 2D nuclear magnetic resonance (NMR) spectroscopy. In the eddy current correction, the phases of the free induction decays (FIDs) of the metabolite (1)H are corrected along the t₂ direction by the phase of the FID of water (1)H.

Highly resolved two-dimensional ¹H spectroscopy of the human brain using ISIS CT-PRESS with resolution enhancement.

In constant time (CT) point-resolved spectroscopy (PRESS), echo centers shift with the fast decay of short T₂* on two-dimensional (2D) time domain (TD) data under inhomogeneous B₀ field like in vivo conditions. Though ¹H decoupling along the F₁ direction is a feature of this method, the tilted and broadened peak pattern on the F₁-F₂ plane after reconstruction causes the peaks to overlap. To enhance resolution to achieve highly resolved 2D CT-PRESS spectra in the human brain, we propose a 2-part window function that comprises an enhancement part for shifting echoes with fast decay and a conventional part, such as Lorentzian, Gaussian, or sine-bell function.

Toward understanding transverse relaxation in human brain through its field dependence.

Apparent transverse-relaxation rate constants (R₂⁺ = 1/T₂⁺) were measured in various regions of the healthy human brain using a multiecho adiabatic spin-echo sequence at five different magnetic fields, 1.5, 1.9, 3, 4.

Non-uniformity correction of human brain imaging at high field by RF field mapping of B1+ and B1-.

A new method of non-uniform image correction is proposed. Image non-uniformity is originated from the spatial distribution of RF transmission and reception fields, represented as B(1)(+) and B(1)(-), respectively. In our method, B(1)(+) mapping was performed invivo by a phase method.

Estimation of brain iron concentration in vivo using a linear relationship between regional iron and apparent transverse relaxation rate of the tissue water at 4.7T.

Maps of the apparent transverse relaxation time (T(2) were collected on a transaxial plane across the basal ganglia in 54 healthy subjects at 4.7T using a multiecho adiabatic spin-echo (MASE) imaging sequence. We attempted to quantify the nonhemin iron concentration ([Fe]) in various brain regions in vivo based on the linear relationship between the apparent relaxation rate constant (R(2) = 1/T(2) and regional [Fe], as demonstrated previously in 12 subjects.

Visualization of seminiferous tubules in rat testes in normal and diseased conditions by high-resolution MRI.

Rat seminiferous tubules were visualized for the first time using high-spatial-resolution MRI and their MRI features were investigated under normal and various kinds of pathological conditions. All testes images were obtained at 4.7 T with a dedicated quadrature surface coil.

Simultaneous observation of glutamate, gamma-aminobutyric acid, and glutamine in human brain at 4.7 T using localized two-dimensional constant-time correlation spectroscopy.

Localized two-dimensional constant-time correlation spectroscopy (CT-COSY) was used to resolve glutamate (Glu), gamma-aminobutyric acid (GABA), and glutamine (Gln) in the human brain at 4.7 T. In this method, three-dimensional localization was achieved using three radio frequency pulses of the CT-COSY module for slice selection.

Apparent transverse relaxation rate in human brain varies linearly with tissue iron concentration at 4.7 T.

Multiple pairs of adiabatic passage pulses were implemented in a spin-echo sequence to achieve accurate measurements of the apparent transverse relaxation time (T(2)(dagger)) in a short scan time. In experiments on agarose gel phantoms with T(2) values ranging from 30 to 105 ms, the measured T(2)(dagger) values were in good agreement with transverse relaxation times measured with a nonselective Carr-Purcell-Meiboom-Gill sequence. In experiments on normal human brain at 4.

In vivo localized 1H MR spectroscopy of rat testes: stimulated echo acquisition mode (STEAM) combined with short TI inversion recovery (STIR) improves the detection of metabolite signals.

A noninvasive NMR technique for evaluating testicular function was explored in this study. Localized in vivo 1H NMR spectroscopy was performed on rat testes using a stimulated echo acquisition mode (STEAM) sequence with a short echo time (TE). In the 1H spectra, large lipid signals dominated the chemical shift range of 0.

Peliosis hepatis and neoplastic/dysplastic lesions in aged male Long-Evans Cinnamon rats: MR imaging with pathologic correlation.

The Long-Evans Cinnamon (LEC) rat, an animal model of Wilson's disease, abnormally accumulates copper in the liver. There have been a lot of reports on preneoplastic and neoplastic hepatic tumors in LEC rats, but few studies have been focused on other lesions. The aim of this study was to describe the MR findings of the liver of LEC rats with pathologic correlation to characterize the hepatic lesions developed in them.

Optical isometric force transducer for measurement of rat skeletal muscle contraction in the NMR spectrometer.

In order to measure force of contraction of the rat gastrocnemius muscle in the NMR spectrometer with a simultaneous observation of 31P NMR spectra, an optical force transducer was constructed using gratings and optical fibers. Muscle contraction was accurately recorded in the spectrometer without interfering with NMR measurements. The half height width of the phosphocreatine (PCr) peak in the presence or absence of the transducer was 5 Hz.

31P nuclear magnetic resonance study on changes in phosphocreatine and the intracellular pH in rat skeletal muscle during exercise at various inspired oxygen contents.

We measured ATP, phosphocreatine (PCr), inorganic phosphate (Pi), and the intracellular pH in rat hindlimb muscles during submaximal isometric exercise with various O2 deliveries using 31P nuclear magnetic resonance spectroscopy (31P NMR) to evaluate changes in energy metabolism in relation to O2 availability. Delivery of O2 to muscles was altered by controlling the fractional concentration of inspired oxygen (F1O2) at 0.50, 0.

MR imaging of non-cancerous hepatic lesions in Long-Evans cinnamon rats.

We measured MR images of the liver of Long-Evans Cinnamon (LEC) rats with pathologic correlation and assessed the effectiveness of MR imaging (MRI) for diagnosis of noncancerous hepatic lesions. T1- and T2-weighted images of their livers were obtained, and the dynamic and delayed studies after intravenous gadolinium injection were also performed. Cholangiofibrosis showed low signal intensity on T1-weighted images and high signal intensity on T2-weighted images.

31P NMR study of acute toxic effects of cadmium chloride on rat liver.

In this study, acute effects of cadmium ions (Cd2+) on energy metabolism in rat livers were analyzed in vivo after intravenous administration using 31P NMR. Both inorganic phosphate (Pi) and nucleotide triphosphate (NTP) peaks of in vivo Cd-treated livers gradually decreased over a 6-h period. In the extract, NTP peaks in Cd-treated livers were lower, as in the in vivo experiments, but the Pi peak was significantly higher than the control.

Proton magnetic resonance imaging and phosphorus-31 NMR studies on the rat brain intoxicated with methyl mercury.

Model rats of methyl mercury intoxication were made by orally administering 5 mg mercury/kg methyl mercury daily for 12 days. Proton magnetic resonance imaging and phosphorus-31 nuclear magnetic resonance spectroscopy measurements were performed on the brain of these model animals in vivo under anesthesia. Proton images contrasted with the longitudinal or transverse relaxation times of protons on water and lipid molecules exhibited an internal structure of the poisoned brain.

Role of cytoplasmic inorganic phosphate in light-induced activation of H(+)-pumps in the plasma membrane and tonoplast of Chara corallina.

A unique variant strain of Chara corallina, which contains little inorganic phosphate in the vacuole ([Pi]v) was isolated. The level of cytoplasmic inorganic phosphate ([Pi]c) in these cells was the same as that in normal cells. Using these unique cells, we studied the change in [Pi]c and the effect of Pi on the activities of electrogenic H(+)-pumps associated with the plasma membrane and tonoplast.

Phosphorus-31 nuclear magnetic resonance study on the effects of endurance training in rat skeletal muscle.

To evaluate changes in muscle energetics following endurance training, we measured phosphorus-31 nuclear magnetic resonance (31P NMR) spectra on rat muscle in vivo before and after training in the same animals. The endurance training lasted for 3 months. The 31P NMR spectra were obtained serially at rest, during exercise by electrical stimulation, and during recovery.

Changes in sarcoplasmic metabolite concentrations and pH associated with the catch contraction and relaxation of the anterior byssus retractor muscle of Mytilus edulis measured by phosphorus-31 nuclear magnetic resonance.

The sarcoplasmic concentrations of phosphorus metabolites and pH (pHin) were measured in the anterior byssus retractor muscle (ABRM) of Mytilus edulis by 31P nuclear magnetic resonance spectroscopy. During an active contraction induced by 10(-3) acetylcholine, the concentration of arginine phosphate ([Arg-P]in) decreased from the resting value of 7.47 +/- 0.

Identification of metabolites of 2-chlorodibenzofuran in the rat.

The hepatic metabolism of 2-chlorodibenzofuran was investigated in the rat. When 2-chloro[14C]dibenzofuran was intravenously administered to bile duct-cannulated rats, about 90% of radioactivity was excreted in bile and urine within 6 hr, the bile being the preferential route. Another group of rats received oral administration of cold 2-chlorodibenzofuran and bile fluid was collected by surgical bile duct cannulation for qualitative analysis.

Evaluation of exercise muscle energetics by NMR.

Magnetic resonance imaging (MRI) is superior to ultrasonography and X-CT especially in density resolution in soft tissue. 31P NMR provides information on metabolism, which has not been obtained in vivo by conventional methods, such as phosphocreatine (PCr), inorganic phosphate (Pi), ATP, and intracellular pH. We used MRI and 31P NMR spectroscopy to study skeletal muscle metabolism of human and rat.

Metabolic changes during experimental cerebral ischemia in hyperglycemic rats, observed by 31P and 1H magnetic resonance spectroscopy.

Progressive cerebral ischemia was induced in seven anesthetized hyperglycemic rats by carotid artery ligation and hemorrhagic hypotension. Phosphorus metabolites, intracellular pH, and lactate in the brain were monitored by 31P and 1H magnetic resonance spectroscopy. Under conditions in which blood flow was low, phosphocreatine (PCr) concentration and intracellular pH decreased and the concentration of lactate increased.

31P-NMR saturation transfer studies of aerobic Escherichia coli cells.

31P-NMR measurements of saturation transfer have been used to measure the flux between Pi and ATP in Escherichia coli cells respiring on an endogenous carbon source. Measurements were made in the wild type and in cells genetically modified to give a 5-fold higher concentration of the F1F0-ATP synthase. The flux in the two cell types was not significantly different.

Photophosphorylation and oxidative phosphorylation in intact cells and chromatophores of an aerobic photosynthetic bacterium, Erythrobacter sp. strain OCh114.

Light-induced ATP synthesis was studied in intact cells and chromatophores of Erythrobacter sp. strain OCh114. ATP synthesis was measured by both the pH method and the luciferin-luciferase luminescence method.