An inorganic functional group approach to the systematic synthesis and reactivity studies of binuclear Mo/S and Mo/S/O complexes

A number of general reactions, based on molybdenum-coordinated sulphido or polysulphido ligands, can account for the synthesis of many members of the [Mo2V(S)n(S2)6-n]2-, [Mo2V(O)(S)n(S2)5-n]2- and [Mo2V(O)2(S)n(S2)4-n]2- homologous series. These reactions include: (a) sulphur addition and sulphur abstraction reactions; (b) oxidative removal of the Sx2- ligands and their replacement by substitutionally labile ligands; (c) oxidation of coodinated RS- ligands by Sx0 fragments, and in situ generation of Sx2- ligands; (d) oxidative dimerization reactions of molybdenum(IV) complexes; and (e) reductive elimination of Sx0 fragments. The synthesis of the new [(Cp)MoV(O)([mu]-S)2MoV(O)S4]- and [(Cp)MoV(O)([mu]-S)2MoV(O)S2]- anions has alowed the use of 1H NMR spectroscopy to monitor the solution behaviour and reactivity of the MoV(O)S2 group. The existence of the MoV(O)S2+S2aiMoV(O)S4 equilibrium has been unequivocally established. The [(Cp)MoV(O)([mu]-S)2MoV(O)S2]- complex gives a vinyl disulphide derivative by insertion of dicarbomethoxyacetylene, DMA, into the Mo-[eta]2-S2 group. Upon prolonged heating to 70[deg]C the vinyl disulphide ligand is converted quantitatively to a dithiolene ligand. The same conversion takes place swiftly at ambient temperatures when catalytic amounts of S8 are present in the reaction medium. Reaction pathways for both the thermal and catalytic conversions have been suggested by 1H NMR studies. Preliminary studies of the utility of the (Et4N)[Mo2O2S8Cl], [Ni(DMF)6][Mo2O2S8Cl]2, (Et4N)2[Mo4O4S18] and (Ph4P)2[Mo2S6] complexes as catalysts for the hydrodesulphurization of thiophene are reported. The Ni/Mo catalyst obtained from [Ni(DMF)6][Mo2O2S8Cl]2 is at least 10 times more effective than a commercial Co/Mo catalyst.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28247/1/0000700.pd

Age Dependence of Systemic Bone Loss and Recovery Following Femur Fracture in Mice

AbstractThe most reliable predictor of future fracture risk is a previous fracture of any kind. The etiology of this increased fracture risk is not fully known, but it is possible that fracture initiates systemic bone loss leading to greater fracture risk at all skeletal sites. In this study we investigated systemic bone loss and recovery following femoral fracture in young (3 month old) and middle-aged (12 month old) mice. Transverse femur fractures were created using a controlled impact, and whole-body bone mineral density (BMD), trabecular and cortical microstructure, bone mechanical properties, bone formation and resorption rates, mouse voluntary movement, and systemic inflammation were quantified at multiple time points post-fracture. We found that fracture led to decreased whole-body BMD in both young and middle-aged mice 2 weeks post-fracture; this bone loss was recovered by 6 weeks in young, but not middle-aged mice. Similarly, trabecular bone volume fraction (BV/TV) of the L5 vertebral body was significantly reduced in fractured mice relative to control mice 2 weeks post-fracture (−11% for young mice, −18% for middle-aged mice); this bone loss was fully recovered by 6 weeks post-fracture in young mice. At 3 days post-fracture we observed significant increases in serum levels of interleukin-6 and significant decreases in voluntary movement in fractured mice compared to control mice, with considerably greater changes in middle-aged mice than in young mice. At this time point we also observed increased osteoclast number on L5 vertebral body trabecular bone of fractured mice compared to control mice. These data show that systemic bone loss occurs after fracture in both young and middle-aged mice, and recovery from this bone loss may vary with age. This systemic response could contribute to increased future fracture risk following fracture, and these data may inform clinical treatment of fractures with respect to improving long-term skeletal health.</jats:p

Cell-based Therapies for Tendon and Ligament Injuries

Tendon and ligament injuries have proved difficult to treat effectively. Cell-based therapies offer the potential to harness the complex protein synthetic machinery of the cell to induce a regenerative response rather than fibrous scarring. This article reviews the current state of play with respect to the clinically used cell preparations for the treatment of tendon and ligaments overstrain injuries