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Structural deformations of lipid hybrid bilayer membranes induced by signal peptideless (SPL) proteins have been studied for the first time using the inherently surface specific nonlinear optical technique of sum frequency generation vibrational spectroscopy. Specifically, deformations of 1,2-distearoylphosphatidylglycerol (DSPG) membranes induced by interaction with FGF-1, a SPL protein which is released as a function of cellular stress through a nonclassical pathway, have been investigated. FGF-1 was found to induce lipid alkyl chain deformations in previously highly ordered DSPG membranes at the extremely low concentration of 1 nM at 60 °C. The deformation process was shown to exhibit a degree of reversibility upon removal of the protein by rinsing with buffer solution.

The swelling behavior of alkanethiol-terminated poly(ethylene glycol) with an average molecular weight of 2180 Da (i.e., ~45 ethylene glycol, EG, units) in contact with water was investigated by neutron reflectometry as a function of the morphology of the PEG-SH layer. Amorphous films at a low grafting density show significant swelling with an increase of the film thickness from ~25 Å in the dry state to ~70 Å in contact with D2O, which corresponds to a total water uptake of ~38 mass %. In contrast, quasi-crystalline monolayers exhibit only a small amount of water penetrating into the film (~8 mass %) with a corresponding change of the layer thickness from ~110 to ~125 Å. The water uptake per EG unit corresponds to the literature value of 1.5 for the amorphous layer and to only 0.25 in the case of the quasi-crystalline film.

We report the synthesis, film formation, protein resistance, and specific antigen binding capability of a carboxy-functionalized poly(ethylene glycol) alkanethiol [HOOC−CH2−(OCH2−CH2)n−O−(CH2)11−SH, n = 22−45]. Despite its polymeric character, the molecule is found to form a densely packed self-assembled monolayer on polycrystalline gold, if adsorbed from dimethylformamide solution. Due to its chain length distribution, the carboxy tailgroups are expected to be partially buried within the film and, thus, do not affect the protein repulsive characteristics of the ethylene glycol moieties when exposed to fibrinogen and immunoglobulin G (IgG). However, if activated by N-hydroxysuccinimide and N-(3-dimethylaminopropyl)-N-ethylcarbodiimide hydrochloride, antibodies can be covalently coupled to the monolayer. While resistance to nonspecific fibrinogen and IgG adsorption is maintained for this biologically active layer, it exhibits high specific antigen binding capacity. The performance of this highly selective surface is compared to that of antibody films prepared by standard aminosilane chemistry.

Optically active thin films in the system Y2Ti2O7-Er2Ti2O7(YETO) have been deposited using the Aerosol-gel process. Depending on the heat-treatment temperature, amorphous or crystalline films could be prepared in the range 600–950°C. The study shows that dilution of erbium ions within a Y2Ti2O7(YTO) matrix allows to prevent short range distance interactions between those ions and to promote good photoluminescence properties of YETO films. These properties are discussed and compared with those of sol-gel derived silica films doped with erbium.

Iron-sulphur ([Fe-S]) clusters are simple inorganic prosthetic groups that are contained in a variety of proteins having functions related to electron transfer, gene regulation, environmental sensing and substrate activation. In spite of their simple structures, biological [Fe-S] clusters are not formed spontaneously. Rather, a consortium of highly conserved proteins is required for both the formation of [Fe-S] clusters and their insertion into various protein partners. Among the [Fe-S] cluster biosynthetic proteins are included a pyridoxal phosphate-dependent enzyme (NifS) that is involved in the activation of sulphur from L-cysteine, and a molecular scaffold protein (NifU) upon which [Fe-S] cluster precursors are formed. The formation or transfer of [Fe-S] clusters appears to require an electron-transfer step. Another complexity is that molecular chaperones homologous to DnaJ and DnaK are involved in some aspect of the maturation of [Fe-S]-cluster-containing proteins. It appears that the basic biochemical features of [Fe-S] cluster formation are strongly conserved in Nature, since organisms from all three life Kingdoms contain the same consortium of homologous proteins required for [Fe-S] cluster formation that were discovered in the eubacteria.

Abstract Erbium-doped germano-silicate thin films of good optical quality were produced by the sol-gel technique. High refractive index changes of up to 0.018 were obtained by sodium-silver ion exchange. Monomode optical waveguides with Gaussian mode profile were fabricated by this technique. It is shown that, if the ion exchange process parameters are well chosen, the influence of the waveguide fabrication on the active properties of the material is negligible.

Thin silica and silica-titania films doped with sulfide nanocrystals of controlled size were fabricated by a method based on the preparation of colloidal particles and their introduction into a glassy matrix through the sol-gel method. Colloidal sols of composition HgxCd1-xS and PbxCd1-xS (with xranging from 0 to 1) were prepared and used to dope alkoxide solutions for the deposition of thin silica and silica-titania films. Optical absorption spectra were taken on both precursor colloidal sols and derived doped films. X-ray diffraction characterization gave structural information on the nature and size of particles in powders obtained by precipitation from colloidal sols and in doped films. The advantages and limits of the investigated systems are discussed in light of possible applications. The nonlinear properties of the most interesting PbS-doped planar waveguides have been investigated in the near-infrared, at 1.064 μm. A reversible nonlinear effect was measured, with n2values ranging from -5 to -20×10-9cm2/kW.

Thin silica and silica-titania films containing CdS and PbS quantum size particles were obtained by separate preparation of the matrix and the colloidal sols and successive mixing. Sulfide particles were obtained by reaction of metal acetates with thioacetamide and control of particle size was achieved by surface capping agents. Powders and thin films deposited on soda-lime slides were prepared and characterized by XRD. Absorption spectra were recorded on films. The nonlinear refractive index was measured by an m-line technique on a CdS-doped sample. The nonlinear effect was found to be reversible and a n2value of -3 10-9cm2/kW was measured.

Herpes simplex virus thymidine kinase (HSV-tk)/ganciclovir (GCV) viral-directed enzyme prodrug gene therapy causes potent, tumor-selective cytotoxicity in animal models in which HSV-tk gene transduction is limited to a minority of tumor cells. The passage of toxic molecules from HSV-tk+ cells to neighboring HSV-tk- cells during GCV therapy is one mechanism that may account for this "bystander" cytotoxicity. To investigate whether gap junction-mediated intercellular coupling could mediate this bystander effect, we used a flow cytometry assay to quantitate the extent of heterocellular coupling between HSV-tk+ murine fibroblasts and both rodent and human tumor cell lines. Bystander tumor cytotoxicity during GCV treatment in a coculture assay was highly correlated (P < 0.001) with the extent of gap junction-mediated coupling. These findings show that gap junction-mediated intercellular coupling contributes to the in vitro bystander effect during HSV-tk/GCV therapy and that retroviral transduction of tumor cells is not required for bystander cytotoxicity.

Thin silica and silica-titania films containing CdS and PbS quantum size particles were obtained by separate preparation of the matrix and the colloidal sols and successive mixing. Sulfide particles were obtained by reaction of metal acetates with thioacetamide and control of particle size was achieved by surface capping agents. Powders and thin films deposited on soda-lime slides were prepared and characterized by XRD. Absorption spectra were recorded on films. The nonlinear refractive index was measured by anm-line technique on a CdS-doped sample. The nonlinear effect was found to be reversible and an2value of −3 10−9cm2/kW was measured.

A planar silica-titania waveguide doped with CdS nanocrystallites has been fabricated on a silicon substrate. A passive nanoporous host layer and a pure silica buffer layer, of thickness 2.2 and 7.5 µm, respectively, were deposited by the sol-gel technique. Crystallites were then precipitated in the porous matrix by soaking in a CdF2 solution followed by reaction in H2S gas, and a sputtered layer of silica was used to seal the structure. The absorption spectrum of an equivalent film indicates crystallites with radii up to ~26 Å, while energy dispersion spectroscopy indicates a dopant concentration of ~0.5 volume %. The third order optical nonlinearity (Kerr effect) was measured using an m-line technique, yielding a value of –5 × 10-9 cm2/kW.

The excitation process of short optical pulses in waveguides by use of prism couplers is studied with a fully dynamic model. A good coupling efficiency is obtained even for short pulses. Fast nonlinear behavior such as power limiting and optical switching is predicted with a response time much shorter than the buildup time of the waveguide coupler. This new result is due to the group-velocity matching between the guided and the pump fields.

We report the case of a young child with Glycogen Storage Disease (GSD) type-Ia who developed echogenic kidneys, medullary calcium deposition and disturbance of renal function. These severe renal abnormalities are seen in young adults whose GSD-I has been ineffectively treated. Renal disease can be considered a major problem in GSD-I.

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