title: Minimization of spectral pattern changes during HRMAS experiments at 37 degrees celsius by prior focused microwave irradiation.
abstract: OBJECTIVE
  High-resolution magic angle spinning (HRMAS) magnetic resonance spectroscopy provides detailed metabolomic information from intact tissue. However, long acquisition times and high rotation speed may lead to timedependent spectral pattern changes, which may affect proper interpretation of results. We report a strategy to minimize those changes, even at physiological recording temperature.
  
  
  METHODS
  Glioblastoma(Gbm) tumours were induced in 12 mice by stereotactic injection of GL261 cells. Animals were sacrificed and tumours were removed and stored in liquid N2. Half of the samples were exposed to focused microwave (FMW) irradiation prior to HRMAS while the other half was not. Time-course experiments (374 min at 37°C, 9.4T, 3,000 Hz spinning rate) were carried out to monitor spectral pattern changes. Differences were assessed with Unianova test while post-HRMAS histopathology analysis was performed to assess tissue integrity.
  
  
  RESULTS
  Significant changes (up to 1.7 fold) were observed in samples without FMW irradiation in several spectral regions e.g. mobile lipids/lactate (0.90-1.30 ppm), acetate (1.90 ppm), N-acetyl aspartate (2.00 ppm), and Choline-containing compounds (3.19-3.25 ppm). No significant changes in the spectral pattern of FMW-irradiated samples were recorded.
  
  
  CONCLUSIONS
  We describe here a successful strategy to minimize spectral pattern changes in mouse Gbm samples using a FMW irradiation system.
authors.affiliation: Departament de Bioquímica i Biologia Molecular, Unitat de Bioquímica de Biociències, Edifici Cs, Universitat Autònoma de Barcelona, 08193 Cerdanyola del Valle`s, Spain.
authors.forename: Myriam
authors.initials: M
authors.lastname: Davila
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Candiota
authors.forename: Martí
authors.initials: M
authors.lastname: Pumarola
authors.forename: Carles
authors.initials: C
authors.lastname: Arus
mesh_terms: D000818:Animals; D001921:Brain / Q000473:pathology*; D001932:Brain Neoplasms / Q000473:pathology*; D045744:Cell Line, Tumor; D002794:Choline / Q000737:chemistry; D005909:Glioblastoma / Q000473:pathology*; D006801:Humans; D008055:Lipids / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D055432:Metabolomics / Q000379:methods; D051379:Mice; D008810:Mice, Inbred C57BL; D008872:Microwaves; D015233:Models, Statistical; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000473:pathology; D013696:Temperature; D013997:Time Factors
chemical_list: D008055:Lipids; D002794:Choline