By studying the relaxation behavior of water 17O nuclei, the complicating effects of cross-relaxation and hydrogen exchange were avoided, and they postulate that the origin of the water 17O relaxation dispersion of BPTI solutions can be explained by a small number of interior water molecules exchanging with bulk water on the submicrosecond time-scale.
Calcium deposition was visualized by fixing cells for 20 min in 4% PFA followed by staining with 0.5% Alizarin Red (Sigma-Aldrich, St.Louis, MO) for 5 min. Following staining with dyes slides were thoroughly washed with water, and nuclei were counterstained using haematoxylin (Pioneer, Essex).
Sections were rinsed in deionised water, cell nuclei were counterstained blue by Mayer's Haemalum and the sections were mounted in Eukitt (Bio-Optica).
To produce image contrast, conventional MRI utilizes the fact that water 1H nuclei of different tissue types have different T1 and T2 relaxation times.
After the final washing with water, the nuclei of the cells were stained using 4′,6-diamidino-2-phenylindole (DAPI, Sigma, USA).
While conventional MRI primarily detects water 1H nuclei, MRS detects proton signals from other molecules such as amino acids (e.g. glutamate), lipids, lactate, N-acetylaspartate (NAA), choline, creatine, and, when present, ethanol.
Thereafter, the sections were stained with Weigert Hematoxylin (Sigma-Aldrich, The Woodlands, TX) for 10 min and washed with distilled water for cell nuclei staining.
High signal intensity of T2 weighted MR imaging reflects the amount of water in the nucleus pulposus.
The cortex has the highest percentage of free water, whereas the nucleus consists of a low amount of free water and a high amount of protein-bound water [ 22].
