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Shear reduction of collisional transport: Experiments and theory : Review,Tutorial and Invited Papers from the 43rd Annual Meeting of the APS Division of Plasma Physics (2002)

Driscoll, C. F. ; Anderegg, F. ; Dubin, D. H. E. ; [et al.]

[S.l.] : American Institute of Physics (AIP)

Physics of Plasmas 9 (2002), S. 1905-1914

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ISSN: 1089-7674

Source: AIP Digital Archive

Topics: Physics

Notes: Experiments and theory on collisional diffusion and viscosity in quiescent single-species plasmas demonstrate enhanced transport in the two-dimensional (2D) bounce-averaged regime, limited by shear in the plasma rotation. For long plasma columns, the measured diffusion agrees quantitatively with recent theories of three-dimensional long-range E×B drift collisions, and is substantially larger than predicted for classical velocity-scattering collisions. For short plasmas, diffusion is observed to be enhanced by Nb, the number of times a thermal particle bounces axially before being separated by shear. Equivalently, recent theory in the 2D bounce-averaged regime shows how diffusion decreases with increasing shear, generalizing the zero-shear perspective which gives Bohm diffusion. Viscosity is similarly enhanced in the 2D regime, but there is presently only qualitative agreement with theory. These results apply to both non-neutral and neutral plasmas, and provide the first rigorous analysis of shear reduction of transport in a paradigmatic system. © 2002 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1454998

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Cytokine Genes are Down-Regulated When Attachment of Entamoeba histolytica to HT-29 Colon Epithelial Cells is Prevented (1997)

KIM, J. M. ; JUNG, H. C. ; JIN, D. Z. ; [et al.]

Oxford, UK : Blackwell Science Ltd

Scandinavian journal of immunology 45 (1997), S. 0

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ISSN: 1365-3083

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Medicine

Notes: Entamoeba histolytica can cause invasive disease by disruption of the intestinal barriers and subsequent lysis of the intestinal cells. Adherence to and contact dependent killing of host cells requires the galactose inhibitable lectin. To elucidate the mechanism whereby E. histolytica influences host defence, the authors assessed the change of proinflammatory cytokine genes expressed by colon epithelial cells in response to co-culture with E. histolytica trophozoites and carbohydrates, including galactose, N-acetyl-galactosamine or N-acetyl-lactosamine, which prevented E. histolytica from attaching to epithelial cells. After HT-29 human colon epithelial cells were co-cultured with E. histolytica trophozoites in the presence or absence of carbohydrates (0.1–100 mm), RNA was extracted from the epithelial cells by an acid guanidinium thiocyanate–phenol–chloroform method. Cytokine gene expression was assessed by quantitative RT-PCR using a synthetic internal standard, and proteins were determined by ELISA. IL-8 mRNA expressed by HT-29 cells in response to E. histolytica trophozoites was downregulated in the presence of galactose, N-acetyl-galactosamine or N-acetyl-lactosamine (0.1–100 mm), and this was paralleled by decreased IL-8 protein secretion. GM-CSF and IL-1α/β mRNAs were also downregulated in those cells in the presence of these agents. These results suggest that the expression of proinflammatory cytokine genes could be inhibited by preventing E. histolytica from attaching to the host's colon epithelial cells.