Surface-plasmon-mediated single-molecule fluorescence through a thin metallic film

We demonstrate that fluorescence of single molecules in the nanometric vicinity of a thin gold film can be effectively excited and detected through the film with an epi-illumination scanning confocal microscope. A full theoretical treatment of the fluorescence signal indicates that both excitation and emission are surface-plasmon mediated. Remarkably, the number of photons detectable from chromophores perpendicular to the interface is enhanced by the presence of the metal.

Altered phenotype and function of blood dendritic cells in multiple sclerosis are modulated by IFN-beta and IL-10

Multiple sclerosis (MS) is assumed to result from autoaggressive T cell-mediated immune responses, in which T helper type 1 (Th1) cells producing cytokines, e.g. IFN-gamma and lymphotoxin promote damage of oligodendrocyte-myelin units. Dendritic cells (DCs) as potent antigen presenting cells initiate and orchestrate immune responses. Whether phenotype and function of DCs with respect to Th1 cell promotion are altered in MS, are not known. This study revealed that blood-derived DCs from MS patients expressed low levels of the costimulatory molecule CD86. In addition, production of IFN-gamma by blood mononuclear cells (MNCs) was strongly enhanced by DCs derived from MS patients. IFN-beta and IL-10 inhibited the costimulatory capacity of DCs in mixed lymphocyte reaction (MLR) and showed additive effects on suppression of IL-12 production by DCs. Correspondingly, DCs pretreated with IFN-beta and IL-10 significantly suppressed IFN-gamma production by MNCs. IFN-beta in vitro also upregulated CD80 and, in particular, CD86 expression on DCs. In vitro, anti-CD80 antibody remarkably increased, while anti-CD86 antibody inhibited DC-induced IL-4 production in MLR. We conclude that DC phenotype and function are altered in MS, implying Th1-biased responses with enhanced capacity to induce Th1 cytokine production. In vitro modification of MS patients' DCs by IFN-beta and IL-10 could represent a novel way of immunomodulation and of possible usefulness for future immunotherapy of MS.

Further studies on Nivalin P-induced changes in muscle fiber membrane processes

Nivalin P, composed of Nivalin (galanthamine hydrobromide) and Pymadin (4-aminopyridine hydrochloride), was applied extracellularly to isolated skeletal muscle fibers during prolonged activity (fatiguing) to better understand the effects of the drug on membrane ionic processes. Changes in intracellular action potential (ICAP) and twitch (Tw) parameters were monitored from treated and untreated fibers during uninterrupted activity (endurance time, ET) produced by repetitive stimulation every 200 msec for 3 min. Nivalin P-induced a shortening of the ET, drastic changes in repolarization of the ICAP corresponding to changes in negative afterpotential and falling area and an initial increase of the Tw amplitude and duration. These results suggest that Nivalin P: (i) inhibits the Na+, K(+)-pump due to nonspecific reduction of Na+ influx, stimulates the Na(+)-Ca2+ exchanger and inhibits K+ conductance; (ii) increases Ca2+ release and delays Ca2+ uptake under sufficient depolarization. It was concluded that fatigue develops faster in the presence of Nivalin P.