An MRI study of solute transport in the intervertebral disc

Objective Quantitative magnetic resonance imaging was used to determine partition coefficients and characteristic time constants for diffusion of MRI contrast agents in disc tissue. Materials and methods Twenty-two excised equine intervertebral discs were exposed to a range of contrast agents: six to manganese chloride, eight to Magnevist (gadopentetate dimeglumine) and eight to Gadovist (gadobutrol), and uptake into the disc was quantified in T1-weighted images. Results Diffusion for all contrast agents was approximately 25% faster in the nucleus than in the outer annulus; disc-average time constants ranged from (2.28 ± 0.23) × 104 s for Gadovist (uncharged, molecular mass 605 g/mol) to (5.07 ± 0.75) × 104 s for the manganese cation (charge + 2). Disc-average partition coefficients ranged from 0.77 ± 0.04 for the anion in Magnevist (charge − 2, molecular mass 548 g/mol) to 5.14 ± 0.43 for the manganese cation. Conclusion The MRI technique provides high-quality quantitative data which correspond well to theoretical predictions, allowing values for partition coefficient and time constant to be readily determined. These measurements provide information to underpin similar studies in vivo and may be used as a model for the transport of nutrients and pharmaceutical agents in the disc.

Crystal structure of bis(4-acetylpyridine-κN)bis(ethanol-κO)bis(thiocyanato-κN)manganese(II)

In the crystal structure of the title compound, [Mn(NCS)2(C7H7NO)2(C2H5OH)2], the MnIIatom is coordinated by twoN-bonded thiocyanate anions, two 4-acetylpyridine ligands, and two ethanol molecules within a slightly distorted octahedron. The asymmetric unit consits of one manganese cation, located on a centre of inversion, one thiocyanate anion, one 4-acetylpyridine ligand and one ethanol molecule in general positions. The discrete complexes are connected by intermolecular O—H...O hydrogen bonds between the alcohol OH group and the carbonyl O atom into chains parallel to [011].

Crystal structure of poly[[(2,2′-bipyridine)manganese(II)]-di-μ-thiocyanato]

In the crystal structure of the polymeric title compound, [Mn(NCS)2(C10H8N2)]n, the MnIIcations are coordinated by one chelating 2,2′-bipyridine ligand and four thiocyanate anions (twoN- and twoS-coordinating), forming a distorted [MnN4S2] octahedron. The asymmetric unit consists of one manganese cation located on a twofold rotation axis and half of a 2,2′-bipyridine ligand, the other half being generated by the same twofold rotation axis, as well as one thiocyanate anion in a general position. The MnIIcations are linked by two pairs of μ1,3-bridging thiocyanate ligands into chains along thecaxis; because the N atoms of the 2,2′-bipyridine ligands, as well as the N and the S atoms of the thiocyanate anions, are eachcis-coordinating, these chains show a zigzag arrangement.