pectations for a second-row transition-metal complex.29 Finally, our pellet spectrum of Cs2 [ 2( 04)4] •2 20 showed a very intense absorption maximum at 250 nm. We consider it most unlikely that intense charge-transfer transitions involving the bridging phosphate or axial water ligands would occur at this low an energy and thus tentatively suggest that this band be assigned to the 123( -»• *)( 2) transition. Comparable UV data for the (29) An alternative assignment for the 670-nm band is '( ( 2) -* <5-(Mo2)) (%. *-'Alg; dipole-forbidden); recent photoelectron spectroscopic studies of other triply metal-metal bonded complexes indicate that the and molecular orbitals of these species are nearly degenerate (Kober, E. M.;Lichtenberger, D. L. J. Ant. Chem. Soc. 1985, 107, 7199-7201).analogous sulfate complexes, however, have not yet been reported.Acknowledgment. We thank W. H. Woodruff and W. P. Schaefer for assistance with the Raman spectroscopy and X-ray photography, respectively, and A. Bino for helpful discussions regarding the preparation of Mo2(HP04)42~. M.D.H. acknowledges the Sun Co. and Standard Oil Co. (Ohio) for graduate fellowships. This work was supported by National Science Foundation Grant CHE84-19828 (H.B.G.) and the Caltech President's Fund (V.M.M.).Registry No. (pyH)3[Mo2(HP04)4]Cl, 71597-13-2; Cs2[Mo2(HP-04)4]•2 20, Mo2(S04)44', Mo2(HP04)42',

AimsAmong people with diabetes, 10–25% will experience a foot ulcer. Research has shown that supplementation with arginine, glutamine and β-hydroxy-β-methylbutyrate may improve wound repair. This study tested whether such supplementation would improve healing of foot ulcers in persons with diabetes.MethodsAlong with standard of care, 270 subjects received, in a double-blinded fashion, (twice per day) either arginine, glutamine and β-hydroxy-β-methylbutyrate or a control drink for 16 weeks. The proportion of subjects with total wound closure and time to complete healing was assessed. In a post-hoc analysis, the interaction of serum albumin or limb perfusion, as measured by ankle–brachial index, and supplementation on healing was investigated.ResultsOverall, there were no group differences in wound closure or time to wound healing at week 16. However, in subjects with an albumin level of ≤ 40 g/l and/or an ankle–brachial index of < 1.0, a significantly greater proportion of subjects in the arginine, glutamine and β-hydroxy-β-methylbutyrate group healed at week 16 compared with control subjects (P = 0.03 and 0.008, respectively). Those with low albumin or decreased limb perfusion in the supplementation group were 1.70 (95% CI 1.04–2.79) and 1.66 (95% CI 1.15–2.38) times more likely to heal.ConclusionsWhile no differences in healing were identified with supplementation in non-ischaemic patients or those with normal albumin, addition of arginine, glutamine and β-hydroxy-β-methylbutyrate as an adjunct to standard of care may improve healing of diabetic foot ulcers in patients with risk of poor limb perfusion and/or low albumin levels. Further investigation involving arginine, glutamine and β-hydroxy-β-methylbutyrate in these high-risk subgroups might prove clinically valuable.

A stable ternary complex formed with vesicle-associated membrane protein 2 (VAMP2) and plasma membrane proteins syntaxin 1A and synaptosome-associated protein of 25 kDa (SNAP-25) is proposed to function in synaptic vesicle exocytosis. To analyze the structural characteristics of this synaptic protein complex, recombinant binary (syntaxin 1A⅐SNAP-25), recombinant ternary, and native ternary complexes were subjected to limited trypsin proteolysis. The protected fragments, defined by amino-terminal sequencing and mass spectrometry, included a carboxyl-terminal region of syntaxin 1A, the cytoplasmic domain of VAMP2, and aminoand carboxyl-terminal regions of SNAP-25. Furthermore, separate amino-and carboxyl-terminal fragments of SNAP-25, when combined with VAMP2 and syntaxin 1A, were sufficient for stable complex assembly. Analysis of ternary complexes formed with full-length proteins revealed that the carboxyl-terminal transmembrane anchors of both syntaxin 1A and VAMP2 were protected from trypsin digestion. Moreover, the stability of ternary complexes was increased by inclusion of these transmembrane domains. These results suggest that the transmembrane domains of VAMP2 and syntaxin 1A contribute to complex assembly and stability and that amino-and carboxyl-terminal regions of SNAP-25 may function as independent domains.Neurotransmitter release represents a specialized form of regulated secretion wherein neurotransmitter-containing synaptic vesicles selectively dock and fuse with the plasma membrane. This process constitutes an essential step in chemical synaptic transmission and is a likely target for regulatory reactions that modulate the strength of synaptic signaling. The identification and biochemical characterization of numerous synaptic vesicle and presynaptic plasma membrane proteins have provided fundamental insight into the molecular mechanisms underlying neurotransmitter release (for reviews see Refs 1 and 2).Among the important findings that have emerged from molecular studies of neurotransmitter release is the central role of a protein complex composed of two presynaptic plasma membrane proteins, syntaxin 1 and synaptosome-associated protein of 25 kDa (SNAP-25), 1 along with one synaptic vesicle protein, vesicle-associated membrane protein 2 (VAMP2; also known as synaptobrevin). Several lines of evidence suggest a primary role for syntaxin 1, SNAP-25, and VAMP2 in synaptic vesicle exocytosis. First, each represents a substrate for cleavage by distinct clostridial neurotoxins, toxins that irreversibly inhibit neurotransmitter release in vivo (3, 4). Furthermore, genetic studies in Drosophila have shown that loss of syntaxin 1 or VAMP2 prevents Ca 2ϩ -dependent exocytosis (5). Finally, the ternary complex formed by all three proteins acts as a receptor for soluble N-ethylmaleimide-sensitive factor (NSF) attachment proteins (SNAPs), cytosolic proteins required in multiple membrane trafficking events (6). Consequently, the syntaxin 1⅐SNAP-25⅐VAMP2 ternary complex is commonly referred to as the synaptic SNA...

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