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Molecular dynamics simulations of two model water/alkane interfaces are used to sort out the effect of molecular shape on the structure and dynamics of the neat interfaces and the orientational dynamics of a solute adsorbed at the interface. The two 1iquidAiquid interfaces are the watednonane interface and the one between water and a single atom representation of the nonane molecule whose potential energy function is selected to give properties close to that of nonane. We find that although the thermodynamic properties and relevant structural properties of the two interfaces are very similar, the reorientation dynamics of the solute probe are faster by about a factor of 2 in the water/"spherical"-nonane system due to different molecular packing and shape.

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These results support the concept of a genetic predisposition in pemphigus. The non-complement-fixing PV-IgG4 and at least one complement-fixing PV-IgG subclass appear to be involved in the pathogenesis of the disease. The absence of PV-IgG4 among relatives who were PV-IgG carriers seems to be linked to the fact that they do not develop pemphigus. The exact nature of this linkage is still unclear.

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Considerable indirect evidence suggests that T lymphocytes have a role in the pathogenesis of psoriasis. The goal of this study was to directly test the ability of T cells to maintain psoriasis pathology. Psoriatic skin was transplanted onto SCID mice, which were then injected with autologous T cells. T cells were cultured from either psoriatic skin lesions or peripheral blood and injected intradermally or intravenously. Control SCID mice transplanted with psoriasis grafts were not injected with T cells. After 10 wk, control psoriatic skin grafts not injected with T cells lost many of the features of psoriasis. Injection of peripheral blood T cells was not able to maintain these psoriatic features. In contrast, the injection of T cells derived from psoriatic skin was able to maintain the psoriatic phenotype. Psoriatic features that were maintained included epidermal thickness and labeling index and expression of HLA-DR, involucrin, and ICAM-1, as well as loss of expression of filaggrin. Injection of skin infiltrating T cells into skin of normal donors on SCID mice did not induce changes of psoriasis. The ability of T cells from lesional skin, but not peripheral blood, to maintain psoriasis suggests that psoriasis is mediated by an autoantigen reactive T cell, which is present at a higher frequency in the psoriatic lesion.

The solvent dynamic response to electronic transitions at several liquid/liquid interfaces is studied using molecular dynamics computer simulations. The interfaces examined are between water and one of four different organic liquids. The electronic transitions involve a change in the permanent dipole of a dipolar solute located at the interface. Two locations of the solute relative to the interface are studied and are compared with the same process in each of the bulk liquids. The different organic liquids are 1-octanol, 1,2-dichloroethane, n-nonane, and carbon tetrachloride. They are selected to give a range of polarity and of interface structure. The solvent dynamic response at the interface is much more complex than in the bulk. The total relaxation involves multiple time scales corresponding to contributions from both solvents and from the unique structural and dynamic properties of the interface. In particular, interfacial water relaxation may contain a slow component not present in the bulk nor at the water liquid/vapor interface.

Background. Four epidemiologic types of Kaposi sarcoma (KS) are known: classic KS, endemic African KS, epidemic or acquired immunodeficiency syndrome–related KS, and KS associated with immunosuppressive therapy. In most of the latter patients, KS was reported to have developed after organ transplantation, particularly renal transplantation. Thirty‐nine patients who have not had a transplant have been reported to have KS associated with corticosteroid therapy. Methods. The authors studied 10 patients with the appearance of KS during corticosteroid therapy (6 men, 4 women; age range, 42–79 years) who were treated with corticosteroids for autoimmune disorders (5 patients), lymphoproliferative disorders (2 patients), and diseases unrelated to the immune system (3 patients). Results. Genetically programmed susceptibility to corticosteroid‐related KS was suggested by the descent of the study patients as well as most of those reported previously. The prognosis was guarded in all the study patients. Conclusions. Corticosteroids should be withdrawn to achieve clinical remission.