title: Visibility of lipid resonances in HR-MAS spectra of brain biopsies subject to spinning rate variation.
abstract: Lipid resonances from mobile lipids can be observed by ¹H NMR spectroscopy in multiple tissues and have also been associated with malignancy. In order to use lipid resonances as a marker for disease, a reference standard from a healthy tissue has to be established taking the influence of variable factors like the spinning rate into account. The purpose of our study was to investigate the effect of spinning rate variation on the HR-MAS pattern of lipid resonances in non-neoplastic brain biopsies from different regions and visualize polar and non-polar lipids by fluorescence microscopy using Nile Red staining. ¹H HR-MAS NMR spectroscopy demonstrated higher lipid peak intensities in normal sheep brain pure white matter biopsies compared to mixed white and gray matter biopsies and pure gray matter biopsies. High spinning rates increased the visibility particularly of the methyl resonances at 1.3 and the methylene resonance at 0.89 ppm in white matter biopsies stronger compared to thalamus and brainstem biopsies, and gray matter biopsies. The absence of lipid droplets and presence of a large number of myelin sheaths observed in white matter by Nile Red fluorescence microscopy suggest that the observed lipid resonances originate from the macromolecular pool of lipid protons of the myelin sheath's plasma membranes. When using lipid contents as a marker for disease, the variable behavior of lipid resonances in different neuroanatomical regions of the brain and at variable spinning rates should be considered. The findings may open up interesting possibilities for investigating lipids in myelin sheaths.
authors.affiliation: Dept. of Clinical Veterinary Medicine, University of Bern, Switzerland. Electronic address: christina.precht@vetsuisse.unibe.ch.
authors.forename: C
authors.initials: C
authors.lastname: Precht
authors.affiliation: Dept. of Clinical Research and Radiology, University of Bern, Switzerland.
authors.forename: G
authors.initials: G
authors.lastname: Diserens
authors.affiliation: Dept. of Clinical Research and Veterinary Public Health, University of Bern, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Oevermann
authors.affiliation: Dept. of Chemistry & Biochemistry, University of Bern, Switzerland.
authors.forename: M
authors.initials: M
authors.lastname: Vermathen
authors.affiliation: Dept. of Clinical Veterinary Medicine, University of Bern, Switzerland.
authors.forename: J
authors.initials: J
authors.lastname: Lang
authors.affiliation: Dept. of Clinical Research and Radiology, University of Bern, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Boesch
authors.affiliation: Dept. of Clinical Research and Radiology, University of Bern, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Vermathen
mesh_terms: D000818:Animals; D001706:Biopsy; D066128:Gray Matter / Q000378:metabolism* / Q000473:pathology; D000069544:Infectious Encephalitis / Q000378:metabolism* / Q000382:microbiology / Q000473:pathology; D050356:Lipid Metabolism; D008089:Listeria monocytogenes; D008088:Listeriosis / Q000378:metabolism* / Q000473:pathology; D009682:Magnetic Resonance Spectroscopy; D009186:Myelin Sheath / Q000378:metabolism* / Q000473:pathology; D012756:Sheep
keywords: Gray matter; Lipid; NMR spectroscopy; Nile Red; White matter