R Deslauriers

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Accurate quantitation of metabolites in biological samples of irregular shape and inhomogeneous composition is generally acknowledged to be difficult. The difficulties are less pronounced with a probe having excellent B1 field homogeneity, high sensitivity, and a resonant frequency independent of sample size and composition. A prototype probe that aims to(More)
BACKGROUND Antegrade and retrograde cerebral perfusion during hypothermic circulatory arrest (HCA) has been reported to provide better brain protection during operation than hypothermic circulatory arrest alone. However, the efficacy of these techniques remains to be fully determined, especially when used for prolonged periods. We used a pig model to(More)
The aim of this work was to investigate whether 1) Rb uptake is reduced in ischemic myocardium, and 2) 87Rb three-dimensional (3D) imaging can detect the ischemic area. Hearts of domestic pigs (n = 8, 20-30 kg) were perfused retrogradely with Krebs-Henseleit buffer in a 7-T, 40-cm horizontal bore magnet interfaced with Bruker MSLX spectrometer. Control (C)(More)
The aim of the study was to compare and analyze different noninvasive indices of cell damage in the isolated pig heart model of regional ischemia. We used (23)Na and (87)Rb MR imaging to evaluate Na(+)/K(+) balance, (31)P MR spectroscopy to measure energetics, and optical spectroscopy to assess oxymyoglobin (MbO(2)). Hearts were subjected to 120-min(More)
K(+) uptake rates were measured in the anterior (An) and posterior (Pos) LV walls of pig hearts before and after regional ischemia and reperfusion using Rb(+) as a K(+) congener and 3D (87)Rb NMR imaging and spectroscopy as detection methods. The hearts were perfused by the Langendorff method with Krebs-Henseleit (KH) buffer and loaded with Rb(+) (4.7 mM,(More)
A simple method has been developed for phasing 31P spectroscopic images acquired with short echo-time (1-2 ms) spin-echo sequences. The technique is based on reconstructing complete echoes in the time domain by the reversal of the complex conjugate of the data. After Fourier analysis, a magnitude reconstruction is used, which no longer broadens the lines.(More)
Trabeculae isolated from human atrial appendages have been used to study preservation of donor hearts for cardiac transplantation. We have developed a perifusion system equipped with a fiber optic strain gauge to study mechanical performance of human atrial trabeculae (10-20 mg) while simultaneously observing the energetic compounds by 31P NMR spectroscopy.(More)
The phase, height, and width of NMR spectral lines from a constant number of nuclei are frequently dependent upon changes in probe Q factor and tuning, caused by motion of the sample and/or changes in its electrical conductivity and size. Thus quantitation of metabolites in biological samples can be difficult. When probe tuning and matching are rendered(More)
A systematic study was performed to optimize the accuracy of kinetic parameters derived from magnetization transfer measurements. Three techniques were investigated: time-dependent saturation transfer (TDST), saturation recovery (SRS), and inversion recovery (IRS). In the last two methods, one of the resonances undergoing exchange is saturated throughout(More)
This study was designed to assess the effects of simultaneous antegrade/retrograde cardioplegia (SARC) on myocardial perfusion and energy metabolism in the region supported by the occluded left anterior descending artery (LAD) in isolated pig hearts. It was found that injection of Gd-DTPA into the aorta during antegrade cardioplegia (AC) did not result in(More)