Salmonella typhimurium SH5014 porins induce the release of tumor necrosis factor alpha (TNF-), interleukin lee (IL-la), and IL-6 by human monocytes and of gamma interferon (IFN-y) and ILH4 by human lymphocytes. Porins at 1 ,ug/ml induce the greatest release of TNF-a, IL-let, and IL-6 by monocytes and of I]LA by lymphocytes, while porins at 5 ,ug/ml induce the greatest release of IFN-y by lymphocytes. The R form of lipopolysaccharide (LPS-R) induces the greatest release of TNF-a and IL-lee by monocytes when used at a low concentration (1 jLg/mI). At higher concentrations (5 and 10 ,ug/ml, respectively), LPS-R induces the maximal release of IL-6 from monocytes and the maximal release of IL-4 from lymphocytes. The S form of LPS (LPS-S) induces the greatest release of TNF-e, IL-le, and IL-6 by monocytes and that of IL-4 by lymphocytes when used at a concentration of 1 ;ag/ml. After stimulation with LPS-S, the largest quantity of TNF-a and IL-let released was less than that obtained after stimulation with LPS-R at the same concentration, while the quantity of IL-6 released was found to be slightly higher than that obtained after stimulation with porins or LPS-R. LPS-S (1 ,ug/ml) induces IFN-y release from lymphocytes in notably smaller quantities than that obtained with LPS-R and slightly larger quantities than that obtained with porins. The preparation of porins used was found to be contaminated with 10 pg of LPS per 10 jLg of porins, a quantity which was found to have no biological effect; furthermore, porin preparations with the addition of polymyxin B gave the same results. Many of the pathophysiologic mechanisms of gram-negative bacterial infections are due to endotoxins acting on tissue directly or via mediators such as cytokines (40). Mediators of these reactions include tumor necrosis factor (TNF), interleukin la (IL-la), and IL-6 (2, 8, 9) released by monocytes. In addition, endotoxins appear to potentiate antigen-specific proliferation of T helper cell lines (4); among the different mediators released by lymphocytes, IL-4 and gamma interferon (IFN-y) are of particular interest. There
The conditions of adenovirus aggregations are analyzed. Adenovirus type 2 was propagated on Hep2 cells; virion aggregation analysis was performed by sedimentation velocity on sucrose gradients. The results show that aggregation depends on: 1) Ionic strength: aggregate formation was verified between 0.005 M and 0.05 M NaCl; 2) pH: at pH 7.1 virus particles are dispersed, 90 per cent of particles are aggregated at pH 4--5; at pH lower than 4 aggregation is not reversible; 3) Particle concentration: the dilution of a stock containing 5 X 10(11) particles/ml decrease rate of aggregate formation until all aggregation is inhibited; 4) Temperature: the degree of aggregation in the 25 to 37 degrees C range is constant but decreases when the temperature falls below 20 degrees, at +4 C there is no aggregation. The aggregation reaction presents a positive deltaH of 17.9 Kcal/mol and a deltaG of --1.32 Kcal/mol.
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