Solid-State NMR Adiabatic TOBSY Provides Enhanced Sensitivity for Multidimensional High-Resolution Magic- Angle-Spinning H1 MR Spectroscopy in Burn Trauma

Burns are lesions often due to direct transfer of energy from any source of heat to the body. The thermal injury may determine severe metabolic alterations due to the liberation of inflammatory mediators and hormonal disturbances induced by stress. Burn trauma in skeletal muscle has both local and systematic effects, as functionally debilitating changes are seen to occur at local and distant site, especially when burn size exceeds 30% of total body surface area. Nuclear magnetic resonance Spectroscopy HRMAS has been used to explore lipidic accumulation after burn trauma. On these bases we perform a solid-state NMR method that maximizes the advantages of high-resolution magic-angle-spinning (HRMAS) 1H MRS applied to intact burn tissue biopsies when compared to more conventional liquid-state NMR approaches. Numerical si ulations and experimental results of an optimized adiabatic TOBSY (Total through Bond correlation SpectroscopY) solidstate NMR pulse sequence for two-dimensional 1H-1H homonuclear scalar-coupling mixing indicate that a significant SNR gain (>100% theoretically and 20-50% experimentally) relative to its liquid-state analogue TOCSY (TOtal Correlation SpectroscopY) sequence is attainable. Multidimensional 1H-MRS is crucial for unambiguous assignment and quantification of overlapping 1H spectra of tissues. Hence, ensuring the best sensitivity is highly desirable. Here we present experiments using our novel 2D TOBSY HRMAS 1H MRS, which aim to suggest its use as a sensitive MR sequence to investigate burn metabolic injury

Glycine as a Biomarker in Brain Tumors

Glycine is a major inhibitory neurotransmitter in the mammalian central nervous system. High levels of glycine have been detected in the brain of patients with hyperglycinemia and in brain tumors in particular glioblastoma multiforme (GBM). Given its significance, an accurate measure of brain glycine is desirable; this is hindered by the fact that its resonance overlaps with the resonances of myo-inositol. Because of myo-inositol\u2019s short TE, glycine can be detected in long TE and when editing, TE-averaged point resolved spectroscopy (PRESS) or 2D J-PRESS are used. Here we employed HRMAS 1H MRS to quantify glycine (Gly) in brain tumor biopsies using the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence. We show that reliable detection of Gly in brain tumor biopsies is feasible using HRMAS 1H MRS at TE of 50 ms with CPMG. With respect to the choice of TE, this is a TE at which the amplitude of the Myo resonance is sufficiently reduced to allow for Gly detection. The Gly resonance, being a singlet at 3.55 ppm that is overlapped by the more intense Myo resonances, cannot be directly edited, but requires approaches that minimize the signal contribution from Myo. Our results show that we can differentiate brain tumor types based on the amount of Gly they contain and are in agreement with prior observations. Especially the distinction between high-grade tumors (i.e., GBM) and metastasis is of clinical significance because it is a distinction not made adequately at present. Here, it is the reduced Myo and high glycine that distinguish GBM from MT, which exhibit both Myo and Gly resonances. We propose Gly as a useful biomarker in brain tumors

Molecular characterization and quantification using state of the art solid-state adiabatic TOBSY NMR in burn trauma

We describe a novel solid-state nuclear magnetic resonance (NMR) method that maximizes the advantages of high-resolution magic-angle-spinning (HRMAS), relative conventional liquid-state NMR approaches, when applied to intact biopsies of skeletal muscle specimens collected from burn trauma patients. This novel method, termed optimized adiabatic TOtal through Bond correlation SpectroscopY (TOBSY) solid-state NMR pulse sequence for two-dimensional (2D) 1H-1H homonuclear scalar-coupling longitudinal isotropic mixing, was demonstrated to provide a 40-60% improvement in signal-to-noise ratio (SNR) relative to its liquid-state analogue TOCSY (TOtal Correlation SpectroscopY). Using 1- and 2-dimensional HRMAS NMR experiments, we identified several metabolites in burned tissues. Quantification of metabolites in burned tissues showed increased levels of lipid compounds, intracellular metabolites (e.g., taurine and phosphocreatine) and substantially decreased water-soluble metabolites (e.g., glutathione, carnosine, glucose, glutamine/ glutamate and alanine). These findings demonstrate that HRMAS NMR Spectroscopy using TOBSY is a feasible technique that reveals new insights into the pathophysiology of burn trauma. Moreover, this method has applications that facilitate the development of novel therapeutic strategies

High-resolution magic angle spinning magnetic resonance spectroscopy detects glycine as a biomarker in brain tumors

The non-essential amino acid neurotransmitter glycine (Gly) may serve as a biomarker for brain tumors. Using 36 biopsies from patients with brain tumors [12 glioblastoma multiforme (GBM); 10 low-grade (LG), including 7 schwannoma and 3 pylocytic astrocytoma; 7 meningioma (MN); 7 brain metastases (MT), including 3 adenocarcinoma and 4 breast cancer] and 9 control biopsies from patients undergoing surgery for epilepsy, we tested the hypothesis that the presence of glycine may distinguish among these brain tumor types. Using high-resolution magic angle spinning (HRMAS) 1H magnetic resonance spectroscopy (MRS), we determined a theoretically optimum echo time (TE) of 50 ms for distinguishing Gly signals from overlapping myo-inositol (Myo) signals and tested our methodology in phantom and biopsy specimens. Quantitative analysis revealed higher levels of Gly in tumor biopsies (all combined) relative to controls; Gly levels were significantly elevated in LG, MT and GBM biopsies (P 640.05). Residual Myo levels were elevated in LG and MT and reduced in MN and GBM (P<0.05 vs. control levels). We observed higher levels of Gly in GBM as compared to LG tumors (P=0.05). Meanwhile, although Gly levels in GBM and MT did not differ significantly from each other, the Gly:Myo ratio did distinguish GBM from MT (P<0.003) and from all other groups, a distinction that has not been adequately made previously. We conclude from these findings that Gly can serve as a biomarker for brain tumors and that the Gly:Myo ratio may be a useful index for brain tumor classification

Microarray analysis suggests that burn injury results in mitochondial dysfunction in human skeletal muscle

Burn injuries to extensive areas of the body are complicated by muscle catabolism. Elucidating the molecular mechanisms that mediate this catabolism may facilitate the development of a medical intervention. Here, we assessed the functional classification of genes that were differentially expressed in skeletal muscle following burn injury in 19 children (5.2±4.0 years of age), (64±15% total burn surface area, TBSA) relative to 13 healthy controls (11.9±6.0 years of age). Microarray analysis of samples taken within 10 days of burn injury revealed altered expression of a variety of genes, including some involved in cell and organelle organization and biogenesis, stress response, wound response, external stimulus response, regulation of apoptosis and intracellular signaling. The genes that encode peroxisome proliferator-activated receptors (PPARs; 3 isotypes PPARα, PPARγ and PPARδ also known as PPARβ or PPARβ/ δ), which may serve as transcriptional nodal points and therapeutic targets for metabolic syndromes, were among those affected. In particular, expression of the main mitochondrial biogenesis factor PPARγ-1β (or PGC-1β) was downregulated (P<0.0001), while the expression of PPARδ was upregulated (P<0.001). Expression of PGC-1α, the closest homolog of PGC-1β was upregulated (P=0.0037), and expression of the gene encoding mitochodrial uncoupling protein 2 (UCP2) was also upregulated (P=0.008). These results suggest that altered PPAR and mitochondrial gene expression soon after burn injury may lead to metabolic and mitochondrial dysfunction in human skeletal muscle.link_to_subscribed_fulltex

In-Vivo High-Resolution Magic Angle Spinning Proton MR Spectroscopy of Drosophila Melanogaster Flies as a Model System to Investigate Trauma, Innate Immunity and Aging

Burns are lesions often due to direct transfer of energy from any source of heat to the body. The thermal injury may determine severe metabolic alterations due to the liberation of inflammatory mediators and hormonal disturbances induced by stress. Burn trauma in skeletal muscle has both local and systematic effects, as functionally debilitating changes are seen to occur at local and distant site, especially when burn size exceeds 30% of total body surface area. Nuclear magnetic resonance Spectroscopy HRMAS has been used to explore lipidic accumulation after burn trauma. On these bases we perform a solid-state NMR method that maximizes the advantages of high-resolution magic-angle-spinning (HRMAS) 1H MRS applied to intact burn tissue biopsies when compared to more conventional liquid-state NMR approaches. Numerical simulations and experimental results of an optimized adiabatic TOBSY (Total through Bond correlation SpectroscopY) solidstate NMR pulse sequence for two-dimensional 1H-1H homonuclear scalar-coupling mixing indicate that a significant SNR gain (>100% theoretically and 20-50% experimentally) relative to its liquid-state analogue TOCSY (TOtal Correlation SpectroscopY) sequence is attainable. Multidimensional 1H-MRS is crucial for unambiguous assignment and quantification of overlapping 1H spectra of tissues. Hence, ensuring the best sensitivity is highly desirable. Here we present experiments using our novel 2D TOBSY HRMAS 1H MRS, which aim to suggest its use as a sensitive MR sequence to investigate burn metabolic injury