Electromagnetic energy transfer in plasmon wires consisting of chains of closely spaced metal nanoparticles can occur below the diffraction limit by means of coupled plasmon modes. Coherent propagation with group velocities that exceed 0.1 c is possible in straight wires and around sharp corners ͑bending radius much less than wavelength of visible light͒. Energy transmission through chain networks is possible at high efficiencies and is a strong function of the frequency and polarization direction of the plasmon mode. Although these structures exhibit transmission losses due to heating of about 3 dB/500 nm, they have optical functionality that cannot be obtained in other ways at a length scale Ӷ1 m.The fundamental physical properties of nanometer-size metal particles have been intensively researched for the last hundred years. 1,2 Until recently, most effort has focused on statistically large numbers of particles in disordered arrays. From this work it is well established that at the surface plasmon frequency light strongly interacts with metal particles and excites a collective electron motion, or plasmon. 2 These frequencies are typically in the visible and near-infrared part of the spectrum. 3 In nanometer size particles ͑much smaller than the wavelength of the exciting light, ͒ plasmon excitations produce an oscillating dipole field.Recent developments in particle synthesis and physical characterization of nanostructures have enabled the investigation of the optical properties of single nanoparticles 4 and ordered arrays of closely spaced nanoparticles. In such arrays collective effects and interparticle interactions play an important role. For example, it has been demonstrated that arrays of particles under broad-beam excitation show collective behavior. 5 Furthermore, numerical simulations have shown that electromagnetic ͑EM͒ energy can be transported below the diffraction limit along linear chains of closely spaced metal nanoparticles. 6 This finding could have important consequences for integrated optics which faces the fundamental limitation that, for the guiding, modulation, and amplification of light, structures are needed that have dimensions comparable to the wavelength of light. 7 The EM energy transport along chains of metal nanoparticles relies on the near-field electrodynamic interaction between metal particles that sets up coupled dipole or plasmon modes. 8 This type of coupling is analogous to the process of resonant energy transfer, which is observed in systems that contain closely spaced optically excited atoms, molecules, or semiconductor nanocrystals. [9][10][11][12] In this paper, the dispersion relation for coupled plasmon modes is developed for a linear chain of equally spaced metal particles using an analytical model that describes the near-field EM interaction between the particles in the dipole limit. The model provides estimates for the group velocity v g and the attenuation coefficient ␣ of the allowed coupled plasmon waves. Furthermore, the transport of EM energy through corners a...

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Adenoviral-mediated gene transfer to the caudate nucleus of Macaca mulatta was accomplished using stereotactic injection of two distinct recombinant Ad5 vectors containing the gene for Escherichia coli beta-galactosidase and the cDNA for rat hypoxanthine-guanine phosphoribosylphosphotransferase (HPRT), respectively. Multiple analyses (including immunohistochemistry, histochemistry, transmission electron microscopy, RNA in situ hybridization, nucleotide pool analysis, and enzyme assay) confirmed efficient expression of beta-galactosidase and rat HPRT. Transgene expression was evident in both neurons and glia. Clinically, no evidence of meningitis or cerebritis was observed and no focal neurological deficits were detected in the animal. These preliminary studies indicate that recombinant adenovirus is capable of mediating high level transgene expression to the brains of higher order mammals.

In this report, we present data showing that a recombinant adenoviral vector (Ad.RSVIL-1ra) containing the cDNA for human interleukin-1 receptor antagonist protein (IL-1ra) can genetically modify synoviocytes both in vitro and in vivo. Human synoviocytes infected with Ad.RSVIL-1ra in vitro expressed and secreted high levels of human IL-1ra that were detected by ELISA of tissue culture supernatants. New Zealand White rabbits that received intra-articular injections of Ad.RSVIL-1ra expressed transgenic IL-1ra in synoviocytes, and secretion was detected for at least 4 weeks post-infection. Further, biological activity of the transgenic IL-1ra was demonstrated by its ability to inhibit IL-1-induced prostaglandin E2 (PGE2) synthesis in vitro and IL-1-induced glycosaminoglycan (GAG) degradation in vivo. These data demonstrate that recombinant adenoviral vectors can mediate the intra-articular expression of anti-inflammatory proteins and may be a reasonable method to deliver therapeutically relevant proteins for the regional treatment of synovial inflammation.