Selective C-3 lithiation of 2,3-dibromo- and 2,3-diiodo-1-methylindoles

Reaction of 2,3-dibromo-1-methylindole with tert-butyllithium at −78 °C followed by treatment with tropylium ion gave 2-bromo-3-cycloheptatrienyl-1-methylindole in a moderate yield, indicating that 2-bromo-3-lithio-1-methylindole would be involved as an intermediate instead of 3-bromo-2-lithio-1-methylindole. The structure of 2-bromo-3-cycloheptatrienyl-1-methylindole was unequivocally determined by a single X-ray analysis. 2,3-Diiodo-1-methylindole also gave a 3-lithio derivative exclusively.     

Effect of Inorganic Components on Thermal Stability of Methylsiloxane-Based Inorganic/Orgnaic Hybrids

The thermal decomposition behavior of methylsiloxane-based inorganic/organic hybrids containing an inorganic component derived from metal alkoxides such as Si(OCH₃)₄, Al(O^sC₄H₉)₃, Ti(OⁱC₃H₇)₄ and Nb(OC₂H₅)₅ was investigated by means of thermogravimetric and differential thermal analysis (TG-DTA), Fourier transform infrared (FT-IR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The decomposition temperature of methyl groups in methylsiloxane-based inorganic/organic hybrids containing an inorganic component derived from metal alkoxides was higher than that in the methylsiloxane-based inorganic/organic hybrid prepared from only CH₃Si(OC₂H₅)₃. In particular, when incorporating Nb and Ti inorganic components, methyl groups in methylsiloxane-based inorganic/organic hybrids decomposed at about 100 and 200^∘C higher temperatures, respectively, than those in the methylsiloxane-based inorganic/organic hybrid prepared from only CH₃Si(OC₂H₅)₃. The incorporation of an inorganic component other than siloxane into methylsiloxane-based inorganic/organic hybrids was found to thermally stabilize the methyl groups of methylsiloxane networks.     

Theoretical studies on water–tetracaine interaction

The action of local anesthetics (LA) is controversial. There is experimental evidence that the unprotonated form of LA penetrates the axon, while the charged form acts in the intracellular phase. To obtain some insight on the structure of the local anesthetics tetracaine and its pharmacological action, we made calculations using the density functional theory (DFT) method. After those calculations, we performed molecular dynamics (MD) simulations in a p, N, T ensemble, in an aqueous environment, on both unprotonated and protonated forms of the molecule. The radial distribution function was used to study water solvent effects, through the characterization of the affinity of tetracaine to water. The results indicate that the molecule has regions with different degree of hydrophobicity, and the N‐terminal of the anesthetic was primarily affected by changes in the protonation state of the anesthetic. The pH‐dependent activity of TTC should then be analyzed in view of local changes in different regions of the molecule, rather than in terms of general effects on the hydrophobicity of the molecule as a whole. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006     

The Effect of Cold Stress on UVB Injury in Mouse Skin and Cultured Keratinocytes

Abstract— The effect of cold stress on skin damage caused by UVB irradiation was investigated both in vivo and in vitro. Ear skin of mice that had been exposed to cold stress at 0°C for 20 min and at 5°C for 24 h was exposed to UVB radiation. Sunburn cell production was less in mice exposed to the lower temperature. In addition, the effect of cold stress on the survival rate of UVB-irradiated rat keratinocytes was examined in a cytotoxicity test, with the results showing that keratinocytes exposed to cold stress of 0°C had a higher survival rate than control cells. To pursue a promising clue for explaining the result, we examined metallothionein (MT) production in rat keratinocytes that had been exposed to cold stress at 0°C. Microfluorometric quantification showed a positive correlation between the time course and the intensity of immunofluorescence for MT, indicating that the molecule is inducible by exposure to cold stress in our experimental system. These results suggest that epidermal cells that have been exposed to cold stress maintain a higher resistance to UV radiation than nonexposed controls in vivo and in vitro , and that MT with radical-scavenging activity might contribute, at least in part, to photoprotection against UVB-induced oxidative damage in mammalian skin.     

The correlation of serum parathyroid hormones among patients with dementia of vascular type, hemodialysis, and bone-joint disorders

PTH levels were analysed in sera of patients receiving maintenance hemodialysis, with the vascular type of dementia and orthopedic patients with bone-joint disorders, using PTH assay kits. There were significant interrelationship among all kinds of PTH levels in the hemodialysis patients, but not in patients with the vascular type of dementia and the bone-joint disorders. Renal functions might be responsible for fragmentation of PTH in blood stream. These results suggested that the measurement of PTH levels is needed to examine various kinds of amino-sequence of PTH levels in keeping normal function of kidney.     

Mechanical properties of Nafion and titania/Nafion composite membranes for polymer electrolyte membrane fuel cells

Measurements of the mechanical and electrical properties of Nafion and Nafion/titania composite membranes in constrained environments are reported. The elastic and plastic deformation of Nafion‐based materials decreases with both the temperature and water content. Nafion/titania composites have slightly higher elastic moduli. Thecomposite membranes exhibit less strain hardening than Nafion. Composite membranes also show a reduction in the long‐time creep of ～40% in comparison with Nafion. Water uptake is faster in Nafion membranes recast from solution in comparison with extruded Nafion. The addition of 3–20 wt % titania particles has minimal effect on the rate of water uptake. Water sorption by Nafion membranes generates a swelling pressure of ～0.55 MPa in 125‐μm membranes. The resistivity of Nafion increases when the membrane is placed under a load. At 23 °C and 100% relative humidity, the resistivity of Nafion increases by ～15% under an applied stress of 7.5 MPa. There is a substantial hysteresis in the membrane resistivity as a function of the applied stress depending on whether the pressure is increasing or decreasing. The results demonstrate how the dynamics of water uptake and loss from membranes are dependent on physical constraints, and these constraints can impact fuel cell performance. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 2327–2345, 2006