PIV EXPERIMENT ON THE GAS-SOLID MULTIPHASE FLOW RELEVANT TO WIND- BLOWN SAND : COMPARISON OF VELOCITY FIELDS OF SAND PARTICLES AND AIR FLOW BY SIMULTANEOUS MEASUREMENT

ABSTRACT We measured simultaneously the air flow velocity and the suspended sand-particles velocity in the turbulent boundary layer, using particle image velocimetry (PIV), to study the wind-blown sand transport. It is important, in the context of the environmental issues, to elucidate the mechanism of the windblown sand, which gives rise to serious problems in arid/desert areas, such as the dust storm and the yellow sand. It is also necessary to understand quantitatively the interaction between the gas phase (air) and the solid phase (sand grains) in the multiphase flow. We found that the momentum exchange between the streamwise and the wall-normal velocities might be inhibited by sand grains and that the streamwise velocity of the gas phase in the multiphase flow was decreased by the momentum exchange between the air and the sand grains. It was observed that gas-phase flow was biased by a cluster of sand grains near a wall

NKG2D⁺ IFN-γ⁺ CD8⁺ T Cells Are Responsible for Palladium Allergy

<div><p>Nickel, cobalt, and chromium are well known to be causal agents of allergic contact dermatitis. Palladium (Pd) can also cause allergic disease and exposure results from wide use of this metal in dental restorations and jewelry. Metal allergy is categorized as a delayed-type hypersensitivity, and metal-responsive T cell clones have been isolated from allergic patients. However, compared to nickel, little is known about the pathology of allergic disease mediated by Pd, and pathogenic T cells are poorly understood. To identify the pathogenic T cells that are responsible for onset of Pd allergy, we enriched metal-responsive lymphocytes by sequential adoptive transfer of involved lymph node cells. Here we show that sequential adoptive transfer gradually increased the incidence and the intensity of Pd allergy, and CD8⁺ T cells are responsible for the disease as CD8⁺ T cell-depleted mice and β2-microglobulin-deficient mice did not develop Pd allergy. In addition, we found that draining lymph node cells skewed toward CD8⁺ T cells in response to Pd challenge in 8th adoptive transferred recipient mice. The CD8⁺ T cells expressed NKG2D, a costimulatory molecule involved in the production of IFN-γ. NKG2D ligand was also induced in Pd-injected tissues. Furthermore, both NKG2D ligand-transgenic mice, where NKG2D is downmodulated, and IFN-γ-deficient mice showed impaired Pd allergy. Taken together, these results indicate that IFN-γ-producing NKG2D⁺ CD8⁺ T cells are responsible for Pd allergy and suggest that NKG2D is a potential therapeutic target for treatment of metal allergy.</p></div

Pd allergy is induced by hapten-specific responseand transferable through pathogenic T cell transfer.

<p>(A) Ear thickness was measured before challenge and at the indicated time point after challenge. CHS reaction was elicited in Pd plus LPS-sensitized mice (left panel) or DNFB-sensitized mice (right panel), as described. As negative controls (open circles), mice were i.p. injected with PBS (left panel) or vehicle alone (AOO) was applied (right panel) followed by challenge with Pd or DNFB. Data represent means ± SD of 10 ear samples and similar results were observed in two independent experiments. Asterisks (11) indicates statistical significance (<i>P</i><0.01) between Pd-challenged mice and DNFB-challenged mice. Lower panel shows combination of sensitization and challenge. (B) BALB/c nude mice were adoptively transferred with naïve SLN cells (open circle) or 8th Pd-SLN cells (filled square) as described. Seven days after the transfer, recipient mice (n = 5–8) were challenged with 10 nmol of Pd. The ear swelling was measured as described in(A). Data are represented as the mean ± SD. Asterisks (11) indicates statistical significance (<i>P</i><0.01). (C) Ear swelling at 24 hours after Pd challenge was compared between 1st, 4th, and 8th adoptive transfer of Pd-SLN cells. Data are represented as the mean ± SD. Asterisks (11) indicates statistical significance (<i>P</i><0.01).</p

Increase in disease development by repeat adoptive transfer of lymphocytes from disease-bearing mice.

*<p>SLN cells from naïve BALB/c mice were adoptively transferred into naïve nude mice.</p