76 research outputs found

    Oscillatory Shear Flow-Induced Alignment of Lamellar Melts of Hydrogen-Bonded Comb Copolymer Supramolecules

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    In this work we present the orientational behavior of comb copolymer-like supramolecules P4VP(PDP)1.0, obtained by hydrogen bonding between poly(4-vinylpyridine) and pentadecylphenol, during large-amplitude oscillatory shear flow experiments over a broad range of frequencies (0.001-10 Hz). The alignment diagram, presenting the macroscopic alignment in T/TODT vs Ο‰/Ο‰c, contains three regions of parallel alignment separated by a region of perpendicular alignment. For our material, the order-disorder temperature TODT = 67 Β°C and Ο‰c, the frequency above which the distortion of the chain conformation dominates the materials’ viscoelasticity, is around 0.1 Hz at 61 Β°C. For the first time flipping from a pure transverse alignment via biaxial transverse/perpendicular alignment to a perpendicular alignment as a function of the strain amplitude was found.

    HIV/SIV Infection Primes Monocytes and Dendritic Cells for Apoptosis

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    Subversion or exacerbation of antigen-presenting cells (APC) death modulates host/pathogen equilibrium. We demonstrated during in vitro differentiation of monocyte-derived macrophages and monocyte-derived dendritic cells (DCs) that HIV sensitizes the cells to undergo apoptosis in response to TRAIL and FasL, respectively. In addition, we found that HIV-1 increased the levels of pro-apoptotic Bax and Bak molecules and decreased the levels of anti-apoptotic Mcl-1 and FLIP proteins. To assess the relevance of these observations in the context of an experimental model of HIV infection, we investigated the death of APC during pathogenic SIV-infection in rhesus macaques (RMs). We demonstrated increased apoptosis, during the acute phase, of both peripheral blood DCs and monocytes (CD14+) from SIV+RMs, associated with a dysregulation in the balance of pro- and anti-apoptotic molecules. Caspase-inhibitor and death receptors antagonists prevented apoptosis of APCs from SIV+RMs. Furthermore, increased levels of FasL in the sera of pathogenic SIV+RMs were detected, compared to non-pathogenic SIV infection of African green monkey. We suggest that inappropriate apoptosis of antigen-presenting cells may contribute to dysregulation of cellular immunity early in the process of HIV/SIV infection

    Suppression by serum of immunoreactivity to a common tumour antigen in cancer patients

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    Leucocytes from 4 cancer patients showed cellular reactivity in the leucocyte adherence inhibition (LAI) assay in the presence of the synthetic cncephalitogenic peptide of human myelin basic protein. All patients exhibited reactivity at a peptide concentration of 500 ng/ml. Leucocytes from 4 non-cancer patients failed to react. Suppression of LAI was detected in all 4 cancer patients by adding their serum to reactive mixtures containing peptide and autologous leucocytes. Each serum was subjected to column chromatography on Sephacryl S-200 to determine the molecular weight distribution of suppressive (blocking) factors. The greatest suppression was found in all cases within the range 90-155 kdalton
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