Effects of solvent molecules on hemi-bonded (CH3SH)2+: infrared absorption of [(CH3SH)2-X]+ with X = H2O, (CH3)2CO, or NH3 and (CH3SH)n+ (n = 3-6).

Three-electron two-center (3e-2c) hemi-bonds play important roles in the oxidation and electron transport of proteins and are implicated to be involved in some neurodegenerative diseases. Our previous investigations on infrared (IR) spectra of (CH3SH)2+ using vacuum-ultraviolet photoionization, infrared dissociation, and time-of-flight detection have shown that (CH3SH)2+ is (3e-2c)-bonded. To investigate the influence of the solvent molecules on the (3e-2c)-bonded (CH3SH)2+ in a supersonic jet, we added H2O or (CH3)2CO or NH3 or (CH3SH)n (n = 1-4) to (CH3SH)2+ and investigated their IR action spectra. The (3e-2c)-bonded (CH3SH)2+ ion core was maintained when a molecule of H2O or (CH3)2CO or CH3SH binds, indicating that the ion core is more stable than the hydrogen bond, whereas the (3e-2c)-bond became broken by a NH3 molecule because the proton transfer led to a more stable hydrogen-bonded structure. The spectral features of the SH-stretching modes of (CH3SH)n+ (n = 3-6) indicate that the (3e-2c)-bonded (CH3SH)2+ ion core is maintained and the first two additional CH3SH are H-bonded to the free SH groups of the ion core. For larger clusters with n = 5 and 6, the additional solvent molecules likely bind to the first solvation shell. These results show also that the (3e-2c)-bonded S∴S structure is more stable than the S∴O and S∴N structures in [(CH3SH)2-X]+ with X = H2O or (CH3)2CO or CH3SH or NH3.

Spectral Evidence of Bevel-Gear-Type Rotation of Benzene around Br in Solid p-H2: Infrared Spectrum of the C6H6Br Radical.

Whether the structure of C6H6X (X = halogen), an intermediate in the halogenation of benzene, is an open or a bridged form has been debated. We produced Br to react with C6H6 upon photolysis in situ of a Br2/C6H6/p-H2 matrix at 3.2 K. In contrast to the C6H6Cl σ-complex reported previously, the observed infrared spectrum indicates that C6H6Br is an open-form π-complex. Furthermore, lines of the two CH out-of-plane bending modes associated mainly with even- and odd-numbered carbons, predicted near 672 and 719 cm-1, merged into a broad line at 697.3 cm-1, indicating that these modes become nearly equivalent as Br migrates from one carbon atom to another. Quantum-chemical calculations support that the benzene ring performs a bevel-gear-type rotation with respect to Br. Observation of only trans-ortho- and trans-para-C6H6Br2 suggests that this gear-type motion allows the additional Br atom to attack C6H6Br only from the opposite side of the Br atom in C6H6Br.

Immunosuppressive therapies attenuate paraquat-induced renal dysfunction by suppressing inflammatory responses and lipid peroxidation.

Although paraquat (PQ) induces oxidative damage and inflammatory responses in the lungs, the mechanism underlying PQ-induced acute kidney injury in patients is unclear. Immunosuppressive therapy with glucocorticoids and the immunosuppressant cyclophosphamide (CP) has been employed to treat patients with PQ poisoning. This study examined whether PQ could concurrently cause renal injury, inflammatory responses, and oxidative damage in the kidneys, and whether CP and dexamethasone (DEX) could suppress PQ-induced alterations. Mice were assigned to eight groups: Control, PQ, DEX, PQ plus DEX, CP, PQ plus CP, DEX plus CP, and PQ plus DEX with CP. DEX, CP, and DEX plus CP reversed PQ-induced renal injury, as indicated by urinary albumin-to-creatinine ratios and urea nitrogen levels in serum. The treatments also attenuated PQ-induced renal infiltration of leukocytes and macrophages and induction of the Il6, Tnf, Icam, Cxcl2, Tlr4, and Tlr9 genes encoding the inflammatory mediators in the kidneys. However, DEX only partially suppressed the macrophage infiltration, whereas DEX plus CP provided stronger protection than DEX or CP alone for the induction of Il6 and Cxcl2. Moreover, through the detection of F2-isoprostanes (F2-IsoPs) and isofurans in the kidneys and lungs and F2-IsoPs in the plasma and urine, the therapies were found to suppress PQ-induced lipid peroxidation, although DEX was less effective. Finally, PQ decreased ubiquinol-9:ubiquinone-9 ratios in the kidneys. This effect of PQ was not found under CP treatment, but the ratio was lower than that of the control group. Our findings suggest that the suppression of PQ-induced inflammatory responses by DEX and CP in the kidneys can mitigate oxidative damage and acute kidney injury.

A comparative study of gold nanocubes, octahedra, and rhombic dodecahedra as highly sensitive SERS substrates.

Gold nanocubes, octahedra, and rhombic dodecahedra with roughly two sets of particle sizes have been successfully synthesized via a seed-mediated growth approach. All six samples were analyzed for comparative surface-enhanced Raman scattering (SERS) activity. All of these Au nanostructures were found to yield strong enhancement at a thiophenol concentration of 10(-7) M and are excellent SERS substrates. Rhombic dodecahedra with a rhombus edge length of 32 nm showed significantly better enhancement than the other samples and can reach a detection limit of 10(-8) M. Simulations of the binding energies of thiophenol on the different faces of gold and electric near-field intensities of these nanocrystals have been performed to evaluate the experimental results. Superior SERS activity of these nanocrystals can be expected toward the detection of many other molecules.

Oral antibiotics attenuate bowel segment reversal-induced systemic inflammatory response and body weight loss in massively bowel-resected rats.

BACKGROUND: Using a massively bowel-resected rat model, our previous study demonstrated that small bowel segment reversal stimulates jejunal hyperplasia but may also increase the possibility of bacterial translocation and the elevation of circulating white blood cells and serum interleukin-6 that may reduce the whole-body anabolism. The aim of this study is to investigate whether oral antibiotics might attenuate the inflammatory responses and might therefore facilitate the beneficial effects of bowel segment reversal. METHODS: Male Wistar rats (approximately 270 g) underwent a 70% small bowel resection with (REV group) or without (CON group) a 3-cm small bowel segment reversal, or underwent a sham operation (SHAM group). After surgeries, half of the animals in the REV group were given oral clindamycin plus amoxicillin (50 plus 50 mg/kg/d, ANT group) for 3 weeks. RESULTS: Oral antibiotics administration significantly attenuated the decreases in feeding efficiency (g of body weight/100 kcal diet) and increases in the circulation of white blood cells, serum nitric oxide, and interleukin-6 (1-way ANOVA, p < .05), which are associated with bowel segment reversal. In addition, antibiotics significantly increased serum concentrations of insulin-like growth factor-I, significantly decreased the total numbers of bacteria in the intestine, and tended to reduce the extent of jejunal hyperplasia in rats with bowel segment reversal. CONCLUSIONS: Our results suggest that oral antibiotics may be used as an adjuvant to attenuate the inflammatory responses and to enhance the anabolic responses in massively bowel-resected patients with bowel segment reversal.