Donald N. Rommereim

High‐resolution 1H NMR spectroscopy in organs and tissues using slow magic angle spinning

It is shown that high‐resolution 1H NMR spectra of intact excised tissues and organs can be obtained by rotating the sample slowly about an axis at the magic angle of 54°44′ with the external magnetic field. In this way tissue and cellular damage invoked by standard magic angle spinning (MAS) experiments, where spinning speeds of several kHz are typically employed, are minimized. Special RF pulse sequences, developed originally in solid state NMR, can be used to produce a spinning sideband‐free isotropic spectrum. In this article the first results are shown of the brain, heart, liver, gluteus muscle, and kidney excised from mice using the 2D‐phase‐altered spinning sidebands (PASS) technique and employing MAS spinning speeds of 43–125 Hz. It was found that with slow sample spinning similar, and in some cases even better, spectral resolutions are obtained as compared with fast MAS. Magn Reson Med 46:88–94, 2001. Published 2001 Wiley‐Liss, Inc.

High-resolution 1H NMR spectroscopy in rat liver using magic angle turning at a 1 Hz spinning rate.

It is demonstrated that a high‐resolution 1H NMR spectrum of excised rat liver can be obtained using the technique of magic angle turning (MAT) at a sample spinning rate of 1 Hz. A variant of the phase‐corrected MAT (PHORMAT) pulse sequence that includes a water suppression segment was developed for the investigation. The spectral resolution achieved with PHORMAT approaches that obtained from a standard magic angle spinning (MAS) experiment at a spinning rate of several kHz. With such ultra‐slow spinning, tissue and cell damage associated with the standard MAS experiment is minimized or eliminated. The technique is potentially useful for obtaining high‐resolution 1H spectra in live animals. Magn Reson Med 47:829–836, 2002.

High-resolution 1H NMR spectroscopy in a live mouse subjected to 1.5 Hz magic angle spinning

It is demonstrated that the resolution of the 1H NMR metabolite spectrum in a live mouse can be significantly enhanced by an ultraslow magic angle spinning of the animal combined with a modified phase‐corrected magic angle turning (PHORMAT) pulse sequence. Proton NMR spectra were measured of the torso and the top part of the belly of a female BALBc mouse in a 2 T field while spinning the animal at a speed of 1.5 Hz. It was found that even in this relatively low field, with PHORMAT an isotropic spectrum is obtained with line widths that are a factor of 4.6 smaller than those obtained in a stationary mouse. It is concluded that in vivo PHORMAT has the potential to significantly increase the utility of 1H NMR spectroscopy for biochemical and biomedical animal research. Magn Reson Med 50:1113–1119, 2003.

Metabolomics in lung inflammation:a high-resolution (1)h NMR study of mice exposedto silica dust.

ABSTRACT Here we report the first 1H NMR metabolomics studies on excised lungs and bronchoalveolar lavage fluid (BALF) from mice exposed to crystalline silica. High-resolution 1H NMR metabolic profiling on intact excised lungs was performed using slow magic angle sample spinning (slow-MAS) 1H PASS (phase-altered spinning sidebands) at a sample spinning rate of 80 Hz. Metabolic profiling on BALF was completed using fast magic angle spinning at 2 kHz. Major findings are that the relative concentrations of choline, phosphocholine (PC), and glycerophosphocholine (GPC) were statistically significantly increased in silica-exposed mice compared to sham controls, indicating an altered membrane choline phospholipids metabolism (MCPM). The relative concentrations of glycogen/glucose, lactate, and creatine were also statistically significantly increased in mice exposed to silica dust, suggesting that cellular energy pathways were affected by silica dust. Elevated levels of glycine, lysine, glutamate, proline, and 4-hydroxyproline were also increased in exposed mice, suggesting the activation of a collagen pathway. Furthermore, metabolic profiles in mice exposed to silica dust were found to be spatially heterogeneous, consistent with regional inflammation revealed by in vivo magnetic resonance imaging (MRI).

Developmental Toxicology Evaluation of 60-Hz Horizontal Magnetic Fields in Rats

Abstract Epidemiological and laboratory studies have indicated various biological effects resulting from exposure to extremely low frequency magnetic fields. The possibility of early embryonic loss and fetal malformations arising from such exposures required investigation. A replicate study, using large numbers of animals, was conducted to determine if 60-Hz magnetic fields would produce developmental toxicity in rats. Systems used previously for electric field exposures were retrofitted to provide magnetic field exposures to small laboratory animals. Large coils, separated from the rat cages, were energized by computer-controlled function generators providing a relatively pure, 1000-μT, 60-Hz, horizontal magnetic field for the high exposure group. Leakage fields to a second system provided a second exposure group with average exposures of 0.61 μT. Ambient fields within a third (control) system were 0.09 μT. Field intensities utilized in this study represent a range of exposures encountered by humans; how...

Application of High-Resolution 1H MAS NMR Spectroscopy to the Analysis of Intact Bones from Mice Exposed to Gamma Radiation

Abstract Herein we demonstrate that high-resolution magic angle spinning (MAS) 1H NMR can be used to profile the pathology of bone marrow rapidly and with minimal sample preparation. The spectral resolution obtained allows several metabolites to be analyzed quantitatively. The level of NMR-detectable metabolites in the epiphysis + metaphysis sections of mouse femur were significantly higher than that observed in the diaphysis of the same femur. The major metabolite damage to bone marrow resulting from either 3.0 Gy or 7.8 Gy of whole-body γ radiation 4 days after exposure were (1) decreased total choline content, (2) increased fatty acids in bone marrow, and (3) decreased creatine content. These results suggest that the membrane choline phospholipid metabolism (MCPM) pathway and the fatty acid biosynthesis pathway were altered as a result of radiation exposure. We also found that the metabolic damage induced by radiation in the epiphysis + metaphysis sections of mouse femur was higher than that of the diaphysis of the same femur. Traditional histopathology analysis was also carried out to correlate radiation damage with changes in metabolites. Importantly, the molecular information gleaned from high-resolution MAS 1H NMR complements the pathology data.