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High-resolution Magic Angle Spinning (high-resolution + magic_angle_spinning)
Selected AbstractsNeonatal Alcohol-Induced Region-Dependent Changes in Rat Brain Neurochemistry Measured by High-Resolution Magnetic Resonance SpectroscopyALCOHOLISM, Issue 10 2008Shonagh K. O'Leary-Moore Background:, Maternal drinking during pregnancy can lead to a range of deleterious outcomes in the developing offspring that have been collectively termed fetal alcohol spectrum disorders (FASDs). There is interest and recognized value in using non-invasive neuroimaging techniques such as magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) to characterize, respectively, structural and biochemical alterations in individuals with FASDs. To date, however, results with MRS have been inconsistent regarding the degree and/or nature of abnormalities. Methods:, High-resolution magic angle spinning (HR-MAS) proton (1H) MRS is an ex vivo neuroimaging technique that can acquire spectra in small punches of intact tissue, providing clinically relevant neurochemical information about discrete brain regions. In this study, HR-MAS 1H MRS was used to examine regional neurochemistry in frontal cortex, striatum, hippocampus, and cerebellum of young rats previously exposed to ethanol as neonates. Key neurochemicals of interest included N-acetyl-aspartate (NAA), glutamate, GABA, glutamine, creatine, choline and myo -inositol. Results:, Daily neonatal alcohol exposure from postnatal day 4 (PN4) through PN9 significantly reduced levels of NAA and taurine in the cerebellum and striatum, and induced sex-dependent reductions in cerebellar glutamate when measured on PN16. In addition, myo -inositol was significantly increased in cerebellum. The frontal cortex and hippocampus were virtually unaffected by this neonatal alcohol exposure. Conclusion:, Results of this research may have implications for understanding the underlying neurobiology associated with FASDs and aid in testing treatments in the future. Ongoing studies are assessing the developmental persistence of and/or maturational recovery from these changes. [source] 1H-HRMAS NMR study of smoked Atlantic salmon (Salmo salar)MAGNETIC RESONANCE IN CHEMISTRY, Issue 9 2010David Castejón Abstract High-resolution magic angle spinning (HRMAS) NMR spectroscopic data of smoked Atlantic salmon (Salmo salar) were fully assigned by combination of one- and two-dimensional-HRMAS experiments. Complete representative spectra, obtained after few minutes of analysis time, revealed a large number of minor and major compounds in the sample. The methodology is limited by the low sensitivity of NMR, and therefore HRMAS only enables the determination of the most relevant components. These were fatty acids (FAs), carbohydrates, nucleoside derivatives, osmolytes, amino acids, dipeptides and organic acids. For the first time, spectra were resolved sufficiently to allow semiquantitative determination in intact muscle of the highly polyunsaturated FA 22:6 ,-3. Additionally, the feasibility of 1H-HRMAS NMR metabolite profiling was tested to identify some bioactive compounds during storage. This profiling was carried out by the non-destructive and direct analysis (i.e. without requiring sample preparation and multiple step procedures) of intact salmon muscle. The proposed procedure can be applied to a large number of samples with high throughput due to the short time of analysis and quick evaluation of the data. Copyright © 2010 John Wiley & Sons, Ltd. [source] An investigation of human brain tumour lipids by high-resolution magic angle spinning 1H MRS and histological analysisNMR IN BIOMEDICINE, Issue 7 2008Kirstie S. Opstad Abstract NMR-visible lipid signals detected in vivo by 1H MRS are associated with tumour aggression and believed to arise from cytoplasmic lipid droplets. High-resolution magic angle spinning (HRMAS) 1H MRS and Nile Red staining were performed on human brain tumour biopsy specimens to investigate how NMR-visible lipid signals relate to viable cells and levels of necrosis across different grades of glioma. Presaturation spectra were acquired from 24 adult human astrocytoma biopsy samples of grades II (8), III (2) and IV (14) using HRMAS 1H MRS and quantified using LCModel to determine lipid concentrations. Each biopsy sample was then refrozen, cryostat sectioned, and stained with Nile Red, to determine the number of lipid droplets and droplet size distribution, and with Haematoxylin and Eosin, to determine cell density and percentage necrosis. A strong correlation (R,=,0.92, P,<,0.0001) was found between the number of Nile Red-stained droplets and the ,1.3,ppm lipid proton concentration by 1H MRS. Droplet sizes ranged from 1 to 10,µm in diameter, and the size distribution was constant independent of tumour grade. In the non-necrotic biopsy samples, the number of lipid droplets correlated with cell density, whereas in the necrotic samples, there were greater numbers of droplets that showed a positive correlation with percentage necrosis. The correlation between 1H MRS lipid signals and number of Nile Red-stained droplets, and the presence of lipid droplets in the non-necrotic biopsy specimens provide good evidence that the in vivo NMR-visible lipid signals are cytoplasmic in origin and that formation of lipid droplets precedes necrosis. Copyright © 2008 John Wiley & Sons, Ltd. [source] High-resolution magic angle spinning MRS of breast cancer tissueNMR IN BIOMEDICINE, Issue 5 2002Beathe Sitter Abstract High-resolution magic angle spinning (HR MAS) may develop into a new diagnostic tool for studying intact tissue samples, and several types of cancer have been investigated with promising results. In this study HR MAS spectra of breast cancer tissue from 10 patients have been compared to conventional high-resolution spectra of perchloric acid extracts of the same tissue type. The HR MAS spectra show resolution comparable to spectra of extracts, and two-dimensional techniques lead to identification of a majority of the constituents. More than 30 different metabolites have been detected and assigned. To our knowledge this is the most detailed assignment of biochemical components in intact human breast tissue. The spectra of intact breast cancer tissue differ from perchloric acid extracts by the presence of lipids and fewer signals in the low field region. HR MAS analysis of intact breast tissue specimens is a rapid method, providing spectra with resolution where relative quantification of the majority of the detected metabolites is possible. Copyright © 2002 John Wiley & Sons, Ltd. [source] HIGH-RESOLUTION MAGIC ANGLE SPINNING NMR ANALYSIS OF WHOLE CELLS OF CHAETOCEROS MUELLERI (BACILLARIOPHYCEAE) AND COMPARISON WITH 13C-NMR AND DISTORTIONLESS ENHANCEMENT BY POLARIZATION TRANSFER 13C-NMR ANALYSIS OF LIPOPHILIC EXTRACTS,JOURNAL OF PHYCOLOGY, Issue 3 2004Matilde S. Chauton Lipid composition in extracted samples of Chaetoceros muelleri Lemmermann was studied with 13C-NMR and distortionless enhancement by polarization transfer (DEPT) 13C-NMR, resulting in well-resolved 13C-NMR spectra with characteristic resonance signals from carboxylic, olefinic, glyceryl, methylene, and methyl groups. The application of a DEPT pulse sequence aided in the assignment of methylene and methine groups. Resonance signals were compared with literature references, and signal assignment included important unsaturated fatty acids such as eicosapentaenoic and docosahexaenoic and also phospholipids and glycerols. Results from the extracted samples were used to assign resonance signals in a high-resolution magic angle spinning (HR MAS) DEPT 13C spectrum from whole cells of C. muelleri. The NMR analysis on whole cells yielded equally good information on fatty acids and also revealed signals from carbohydrates and amino acids. Broad resonance signals and peak overlapping can be a problem in whole cell analysis, but we found that application of HR MAS gave a well-resolved spectrum. The chemical shift of metabolites in an NMR spectrum depends on the actual environment of nuclei during analysis, and some differences could therefore be expected between extracted and whole cell samples. The shift differences were small, and assignment from analysis of lipophilic extract could be used to identify peaks in the whole cell spectrum. HR MAS 13C-NMR therefore offers a possibility for broad-range metabolic profiling directly on whole cells, simultaneously detecting metabolites that are otherwise not detected in the same analytical set up and avoiding tedious extraction procedures. [source] Cerebral activation by fasting induces lactate accumulation in the hypothalamusMAGNETIC RESONANCE IN MEDICINE, Issue 2 2009Inęs R. Violante Abstract Carbon-13 (13C) high-resolution magic angle spinning (HR-MAS) spectroscopy was used to investigate the neuroglial coupling mechanisms underlying appetite regulation in the brain of C57BL/6J mice metabolizing [1- 13C]glucose. Control fed or overnight fasted mice received [1- 13C]glucose (20 ,mol/g intraperitoneally [i.p.]), 15 min prior to brain fixation by focused microwaves. The hypothalamic region was dissected from the rest of the brain and 13C HR-MAS spectra were obtained from both biopsies. Fasting resulted in a significant increase in hypothalamic [3- 13C]lactate and [2- 13C],-aminobutyric acid (GABA) relative to the remaining brain. Administration of the orexigenic peptide ghrelin (0.3 nmol/g i.p.) did not increase hypothalamic [3- 13C]lactate or [2- 13C]GABA, suggesting that ghrelin signaling is not sufficient to elicit all the metabolic consequences of hypothalamic activation by fasting. Our results indicate that the hypothalamic regulation of appetite involves, in addition to the well-known neuropeptide signaling, increased neuroglial lactate shuttling and augmented GABA concentrations. Magn Reson Med, 2009. © 2009 Wiley-Liss, Inc. [source] Evaluation of lactate and alanine as metabolic biomarkers of prostate cancer using 1H HR-MAS spectroscopy of biopsy tissuesMAGNETIC RESONANCE IN MEDICINE, Issue 3 2008May-Britt Tessem Abstract The goal of this study was to investigate the use of lactate and alanine as metabolic biomarkers of prostate cancer using 1H high-resolution magic angle spinning (HR-MAS) spectroscopy of snap-frozen transrectal ultrasound (TRUS)-guided prostate biopsy tissues. A long-echo-time rotor-synchronized Carr-Purcell-Meiboom-Gill (CPMG) sequence including an electronic reference to access in vivo concentrations (ERETIC) standard was used to determine the concentrations of lactate and alanine in 82 benign and 16 malignant biopsies (mean 26.5% ± 17.2% of core). Low concentrations of lactate (0.61 ± 0.28 mmol/kg) and alanine (0.14 ± 0.06 mmol/kg) were observed in benign prostate biopsies, and there was no significant difference between benign predominantly glandular (N = 54) and stromal (N = 28) biopsies between patients with (N = 38) and without (N = 44) a positive clinical biopsy. In biopsies containing prostate cancer there was a highly significant (P < 0.0001) increase in lactate (1.59 ± 0.61 mmol/kg) and alanine (0.26 ± 0.07 mmol/kg), and minimal overlap with lactate concentrations in benign biopsies. This study demonstrates for the first time very low concentrations of lactate and alanine in benign prostate biopsy tissues. The significant increase in the concentration of both lactate and alanine in biopsy tissue containing as little as 5% cancer could be exploited in hyperpolarized 13C spectroscopic imaging (SI) studies of prostate cancer patients. Magn Reson Med 60:510,516, 2008. © 2008 Wiley-Liss, Inc. [source] High-resolution magic angle spinning proton NMR analysis of human prostate tissue with slow spinning ratesMAGNETIC RESONANCE IN MEDICINE, Issue 3 2003Jennifer L. Taylor Abstract The development of high-resolution magic angle spinning (HR-MAS) NMR spectroscopy for intact tissue analysis and the correlations between the measured tissue metabolites and disease pathologies have inspired investigations of slow-spinning methodologies to maximize the protection of tissue pathology structures from HR-MAS centrifuging damage. Spinning sidebands produced by slow-rate spinning must be suppressed to prevent their complicating the spectral region of metabolites. Twenty-two human prostatectomy samples were analyzed on a 14.1T spectrometer, with HR-MAS spinning rates of 600 Hz, 700 Hz, and 3.0 kHz, a repetition time of 5 sec, and employing various rotor-synchronized suppression methods, including DANTE, WATERGATE, TOSS, and PASS pulse sequences. Among them, DANTE, as the simplest scheme, has shown the most potential in suppression of tissue water signals and spinning sidebands, as well as in quantifying metabolic concentrations. Magn Reson Med 50:627,632, 2003. © 2003 Wiley-Liss, Inc. [source] Investigation of metabolite changes in the transition from pre-invasive to invasive cervical cancer measured using 1H and 31P magic angle spinning MRS of intact tissueNMR IN BIOMEDICINE, Issue 2 2009Sonali S. De Silva Abstract The aim of this study was to determine the metabolic changes in the transition from pre-invasive to invasive cervical cancer using high-resolution magic angle spinning (HR-MAS) MRS. Biopsy specimens were obtained from women with histologically normal cervix (n,=,5), cervical intraepithelial neoplasia (CIN; mild, n,=,5; moderate/severe, n,=,40), and invasive cancer (n,=,23). 1H HR-MAS MRS data were acquired using a Bruker Avance 11.74,T spectrometer (Carr,Purcell,Meiboom,Gill sequence; TR,=,4.8,s; TE,=,135,ms; 512 scans; 41,min acquisition). 31P HR-MAS spectra were obtained from the normal subjects and cancer patients only (as acetic acid applied before tissue sampling in patients with CIN impaired spectral quality) using a 1H-decoupled pulse-acquire sequence (TR,=,2.82,s; 2048 scans; 96,min acquisition). Peak assignments were based on values reported in the literature. Peak areas were measured using the AMARES algorithm. Estimated metabolite concentrations were compared between patient diagnostic categories and tissue histology using independent samples t tests. Comparisons based on patient category at diagnosis showed significantly higher estimated concentrations of choline (P,=,0.0001) and phosphocholine (P,=,0.002) in tissue from patients with cancer than from patients with high-grade dyskaryosis, but no differences between non-cancer groups. Division by histology of the sample also showed increases in choline (P,=,0.002) and phosphocholine (P,=,0.002) in cancer compared with high-grade CIN tissue. Phosphoethanolamine was increased in cancer compared with normal tissue (P,=,0.0001). Estimated concentrations of alanine (P,=,0.01) and creatine (P,=,0.008) were significantly reduced in normal tissue from cancer patients compared with normal tissue from non-cancer patients. The estimated concentration of choline was significantly increased in CIN tissue from cancer patients compared with CIN tissue from non-cancer patients (P,=,0.0001). Estimated concentrations of choline-containing metabolites increased from pre-invasive to invasive cervical cancer. Concurrent metabolite depletion occurs in normal tissue adjacent to cancer tissue. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||