SynopsisThe field-dependent 23Na nuclear relaxation in aqueous DNA solutions has been obtained for a range of temperatures, including the DNA melting region. At least two correlation times are needed to characterize the spectral density function for the 23Na relaxation. For the slow process (with the largest correlation time), the temperature dependence of the coupling constant and the correlation time were determined, and important premelting effects were observed. Possible origins of the slow process are discussed. The last process is shown to be correlated with the properties of the hydration water of DNA as reflected by the *70 relaxation rates in these solutions. The influence of the polyelectrolyte and NaCl concentrations on the 23Na relaxation rate is compared with previous results from solutions of linear flexible polyelectrolytes.

In several skin diseases, both the lipid composition and organization in the stratum corneum (SC) are altered which contributes to the impaired skin barrier function in patients. One of the approaches for skin barrier repair is treatment with topical formulations to normalize SC lipid composition and organization. Vernix caseosa (VC), a white cheesy cream on the skin during gestational delivery, has shown to enhance skin barrier repair. In this study, we examined how a fatty acid (FA) containing formulation mimicking the lipid composition of VC interacts with the lipid matrix in the SC. The formulation was applied on ex vivo human skin after SC removal. Subsequently, the ex vivo human skin generated SC during culture. The effect of FA containing formulations on the lipid organization and composition in the regenerated SC was analysed by Fourier transform infrared (FTIR) spectroscopy and liquid chromatography mass spectroscopy (LC/MS), respectively. FTIR results demonstrate that the FAs are intercalated in the lipid matrix of the regenerated SC and partition in the same lattice with the endogenous SC lipids, thereby enhancing the fraction of lipids forming an orthorhombic (very dense) packing in the SC. LC/MS data show that the topically applied FAs are elongated before intercalation in the lipid matrix and are thus involved in the lipid biosynthesis in the skin.

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Me t by1 cis-9,cis-I 2-octadecadienoate (methyl linoleate; e9,c12) and the corresponding eis, trans and trans, trans geometric isomers (c9,t12 and t9,t12) were hydrogenated at 40 C and atmospheric hydrogen pressure in acetone as solvent, with nonmetallic palladium-on-resin catalyst. These catalysts were prepared by impregnation of cationic exchange resins with an aqueous solution of palladium dichloride. The methyleneinterrupted dienes were hydrogenated to the monoene stage with almost infinite selectivity, especially with c9,c12, whereas t9,t12 was hydrogenated somewhat less selectively. The latter isomer was reduced considerably more slowly than the first, whereas c9,t12 occupied an intermediate position. The hydrogenation proceeded for an important part via a straightforward reduction of one of the double bonds, though conjugation prior to hydrogenation also occurred. The methylene-interrupted dienes isomerized to a high degree geometrically during hydrogenation, but they scarcely isomerized positionally, resulting in small amounts of inactive ethylene-interrupted dienes.