Twelvefold Functionalization of an Icosahedral Surface by Total Esterification of [B12(OH)12]2-: 12(12)-Closomers

No Abstract     

CYTOKINE RELEASE BY PERIPHERAL BLOOD MONONUCLEAR CELLS IS AFFECTED BY 8-METHOXYPSORALEN PLUS UV-A

Psoralen plus UV-A (PUVA) is an effective therapy for psoriasis but also for other inflammatory dermatoses. The precise mechanisms of action, however, are not absolutely clear. Therefore, the effect of PUVA on the release of the proinflammatory cytokines interleukin (IL)-1, IL-6, IL-8 and tumor necrosis factor alpha (TNFα) was studied. Peripheral blood mononuclear cells (PBMC) obtained from humans were incubated with 8-methoxypsoralen (8-MOP) and exposed to UV-A (20 kJ/m²). This treatment resulted in a significant reduction of IL-6 and IL-8 amounts in the supernatants. In addition, an inhibition of IL-1β and TNFα production by lipopolysaccharide (LPS)-stimulated PBMC was observed upon PUVA treatment. Accordingly, northern blot analysis showed decreased levels of mRNA encoding for IL-1β, IL-6, IL-8 and TNFα in PUVA-treated PBMC. Finally PBMC were obtained from psoriatics undergoing oral photochemotherapy before the beginning and after completion of treatment. The PBMC collected after PUVA spontaneously produced significantly less IL-6 and IL-8 in comparison to the respective samples obtained before therapy. A similar suppression of IL-1β and TNFα by in vivo PUVA was found in LPS-stimulated PBMC. The present data demonstrate that PUVA both in vitro and in vivo suppresses the production of the proinflammatory cytokines IL-1β, IL-6, IL-8 and TNFα by PBMC. Because these cytokines are important in the mediation of inflammatory reactions, one may speculate that the inhibitory effects could contribute to the antiinflammatory activity of PUVA.     

CONCERNING THE ORIGIN OF CHARGE AT THE POLYSTYRENE PARTICLE/WATER INTERFACE

The electrophoretic mobility behavior of well-characterized polystyrene latex particles, carrying one type of surface functional endgroups, has been studied as a function of pH. At low pH, the interaction of protons with the functional endgroups increased in the order: Hydroxyl > carboxyl > sulfate; at high pH the order of interaction was reversed; and at intermediate pH no interactions were observed. The particles of the polystyrene latexes in their different forms at the intermediate pH range, dispersed in deionized water, all exhibited the same mobility irrespective of the functional endgroup. The origin of charge in these systems is explained as being the result of either the preferential adsorption of hydroxyl ions or an electron - injection mechanism due to the overlap of local intrinsic molecular - ion states in polystyrene and water. At low concentrations of functional endgroups, the surface properties of the polystyrene latexes are largely dependent upon the hydrophobic nature of the surface.