Effects of an interleukin-15 antagonist on systemic and skeletal alterations in mice with DSS-induced colitis.

Inflammatory bowel diseases are commonly complicated by weight and bone loss. We hypothesized that IL-15, a pro-inflammatory cytokine expressed in colitis and an osteoclastogenic factor, could play a central role in systemic and skeletal complications of inflammatory bowel diseases. We evaluated the effects of an IL-15 antagonist, CRB-15, in mice with chronic colitis induced by oral 2% dextran sulfate sodium for 1 week, followed by another 1% for 2 weeks. During the last 2 weeks, mice were treated daily with CRB-15 or an IgG2a control antibody. Intestinal inflammation, disease severity, and bone parameters were evaluated at days 14 and 21. CRB-15 improved survival, early weight loss, and colitis clinical score, although colon damage and inflammation were prevented in only half the survivors. CRB-15 also delayed loss of femur bone mineral density and trabecular microarchitecture. Bone loss was characterized by decreased bone formation, but increased bone marrow osteoclast progenitors and osteoclast numbers on bone surfaces. CRB-15 prevented the suppression of osteoblastic markers of bone formation, and reduced osteoclast progenitors at day 14, but not later. However, by day 21, CRB-15 decreased tumor necrosis factor α and increased IL-10 expression in bone, paralleling a reduction of osteoclasts. These results delineate the role of IL-15 on the systemic and skeletal manifestations of chronic colitis and provide a proof-of-concept for future therapeutic developments.

Borcherds products and arithmetic intersection theory on Hilbert modular surfaces

We prove an arithmetic version of a theorem of Hirzebruch and Zagier saying that Hirzebruch-Zagier divisors on a Hilbert modular surface are the coefficients of an elliptic modular form of weight 2. Moreover, we determine the arithmetic selfintersection number of the line bundle of modular forms equipped with its Petersson metric on a regular model of a Hilbert modular surface, and we study Faltings heights of arithmetic Hirzebruch-Zagier divisors.

In vitro production of cattle blastocysts in chemically defined medium with or without insulin supplementation

Selostus: Insuliinin vaikutus naudan blastokystien tuottamiseen in vitro kemiallisesti tunnetussa liuoksessa

Nucleation and growth of GaN nanorods on Si (111) surfaces by plasma-assisted molecular beam epitaxy - The influence of Si- and Mg-doping

The self-assembled growth of GaN nanorods on Si (111) substrates by plasma-assisted molecular beam epitaxy under nitrogen-rich conditions is investigated. An amorphous silicon nitride layer is formed in the initial stage of growth that prevents the formation of a GaN wetting layer. The nucleation time was found to be strongly influenced by the substrate temperature and was more than 30 min for the applied growth conditions. The observed tapering and reduced length of silicon-doped nanorods is explained by enhanced nucleation on nonpolar facets and proves Ga-adatom diffusion on nanorod sidewalls as one contribution to the axial growth. The presence of Mg leads to an increased radial growth rate with a simultaneous decrease of the nanorod length and reduces the nucleation time for high Mg concentrations.

Model for the emission of Si+ ions during oxygen bombardment of Si(100) surfaces

The variation in the emission of Si+ ions from ion-beam-induced oxidized silicon surfaces has been studied. The stoichiometry and the electronic structure of the altered layer has been characterized using x-ray photoelectron spectroscopy (XPS). The XPS analysis of the Si 2p core level indicates the strong presence of suboxide chemical states when bombarding at angles of incidence larger than 30 °. Since the surface stoichiometry or degree of oxidation varies with the angle of incidence, the corresponding valence-band structures also differ among each other. A comparison between experimental measurements and theoretically calculated Si and SiO2 valence bands indicates that the valence bands for the altered layers are formed by a combination of those two. Since Si-Si bonds are present in the suboxide molecules, the top of the respective new valence bands are formed by the corresponding 3p-3p Si-like subbands, which extend up to the Si Fermi level. The changes in stoichiometry and electronic structure have been correlated with the emission of Si+ ions from these surfaces. From the results a general model for the Si+ ion emission is proposed combining the resonant tunneling and local-bond-breaking models.

Innate sensors for Gram-positive bacteria.

More than half of invasive bacterial infections are Gram-positive in origin. This class of bacteria has neither endotoxins nor an outer membrane, yet it generates some of the most powerful inflammatory responses known in medicine. Some recent seminal studies go a long way toward settling the controversies that surround the process by which Gram-positive bacterial surfaces trigger the human immune system. Although the components of the cell wall are now chemically defined in exquisite detail and the interaction with the toll-like receptor 2 pathway has been discovered, it is only very recently that definitive studies combining these advanced biochemical and cell biological tools have been carried out. It is these breakthrough studies that have finally confirmed the paradigm of innate sensors for Gram-positive bacteria.

Sorting on periodic surfaces

Particles moving on crystalline surfaces and driven by external forces or flow fields can acquire velocities along directions that deviate from that of the external force. This effect depends upon the characteristics of the particles, most notably particle size or particle index of refraction, and can therefore be (and has been) used to sort different particles. We introduce a simple model for particles subject to thermal fluctuations and moving in appropriate potential landscapes. Numerical results are compared to recent experiments on landscapes produced with holographic optical tweezers and microfabricated technology. Our approach clarifies the relevance of different parameters, the direction and magnitude of the external force, particle size, and temperature.

From subdiffusion to superdiffusion of particles on solid surfaces

We present a numerical and partially analytical study of classical particles obeying a Langevin equation that describes diffusion on a surface modeled by a two-dimensional potential. The potential may be either periodic or random. Depending on the potential and the damping, we observe superdiffusion, large-step diffusion, diffusion, and subdiffusion. Superdiffusive behavior is associated with low damping and is in most cases transient, albeit often long. Subdiffusive behavior is associated with highly damped particles in random potentials. In some cases subdiffusive behavior persists over our entire simulation and may be characterized as metastable. In any case, we stress that this rich variety of behaviors emerges naturally from an ordinary Langevin equation for a system described by ordinary canonical Maxwell-Boltzmann statistics.

An analytical approach to sorting in periodic and random potentials

There has been a recent revolution in the ability to manipulate micrometer-sized objects on surfaces patterned by traps or obstacles of controllable configurations and shapes. One application of this technology is to separate particles driven across such a surface by an external force according to some particle characteristic such as size or index of refraction. The surface features cause the trajectories of particles driven across the surface to deviate from the direction of the force by an amount that depends on the particular characteristic, thus leading to sorting. While models of this behavior have provided a good understanding of these observations, the solutions have so far been primarily numerical. In this paper we provide analytic predictions for the dependence of the angle between the direction of motion and the external force on a number of model parameters for periodic as well as random surfaces. We test these predictions against exact numerical simulations.

Characterizing emission and breathing-zone concentrations following exposure cases to fluororesin-based waterproofing spray mists.

Measurements and simulations were performed to assess workers' exposure to solvent vapors and aerosols during the waterproofing of a tiled surface. This investigation followed two recent incidents in the same company where workers experienced acute respiratory illness after spraying a stain-repellent resin containing fluorinated polymers on stone-tiled walls and floors. Because the waterproofing activity had been done for years at the tile company without encountering any exposure problems prior to these cases, it was strongly suspected that the incidents were linked to a recent change in the composition of the coating mixture. Experimental measurements and simulations indicated that the emission rate of particles smaller than 10 microm may be estimated at 0.66 mg/sec (SD 0.10) for the old resin and at 0.37 mg/sec (SD 0.04) for the new one. The measurement of the solvent emission rate from surfaces coated with the two resins indicated that shortly after spraying, the emission was in the range of 18 to 20 mg/sec x m2 and was similar for both products. Solvent and overspray emission rates were introduced in a two-zone compartment model. The results obtained in the near-field indicate significant exposure to overspray mist (7 and 34 mg/m3 for new resin) and solvent vapors (80 to 350 ppm for the new resin). It was also shown that the introduction of the new resin tended to significantly decrease the levels of solvents and particulates in the workers' breathing zone. These results strongly suggest that cases of acute respiratory illness are related to the specific toxicity of the fluorinated polymer itself. The fact that the same polymer is used in various commercial products raises concern regarding other possible occupational and domestic exposures.

Magnetoresistance at artificial interfaces in the itinerant SrRuO3 ferromagnet

The magnetoresistance across interfaces in the itinerant ferromagnetic oxide SrRuO3 have been studied. To define appropriately the interfaces, epitaxial thin films have been grown on bicrystalline and laser-patterned SrTiO3 substrates. Comparison is made with results obtained on similar experiments using the double-exchange ferromagnetic oxide La2/3Sr1/3MnO3. It is found that in SrRuO3, interfaces induce a substantial negative magnetoresistance, although no traces of the low-field spin tunneling magnetoresistance are found. We discuss these results on the basis of the distinct degree of spin polarization in ruthenates and manganites and the different nature of the surface magnetic layer formed at interfaces.

Magneto-optical Kerr effect in laser-patterned La2/3Sr1/3MnO3 epitaxial thin films

In this study, we have performed magneto-optical Kerr effect (MOKE) measurement on epitaxial La2/3Sr1/3MnO3 thin films containing artificial interfaces created by laser-patterning the SrTiO3 substrate. The observed increase of the resistivity and of the high-field magnetoresistance when measuring the films across the interface arrays are related to the reduction of the magnetization of the interfaces with respect to the rest of the film. As observed by the local MOKE probe, the structural disorder in the manganite film induced by the underlying patterned substrate leads to a large spin disorder responsible for a strong high-field susceptibility of the resistance.