Product yields measured by high-performance liquid chromatography from chemical trapping of Cl -, Br -, and H2O by an aggregate-bound arenediazonium ion in cetyltrialkylammonium halide {(CTRA)X, R ) Me, Et, n-Pr, and n-Bu; X ) Cl, Br}, micelles are used to estimate, simultaneously, interfacial counterion, Xm, and water, H2Om, concentrations as a function of [(CTRA)X] and tetramethylammonium halide concentrations, [(TMA)X]. The results are interpreted by using a two-site pseudophase model. Values of Xm and H2Om are estimated by assuming that when the product yields from reaction of a long-tail aggregatebound arenediazonium ion in micelles are the same as the product yields from reaction of its short chain analogue in an aqueous quaternary ammonium ion salt solution, then Xm ) [Xw] and H2Om ) [H2Ow] in those solutions. The results show that Xm and H2Om are functions of headgroup size, surfactant concentration, and aqueous counterion concentration and type. Plots of Xm against [(CTRA)X] at a series of salt concentrations fall on separate curves. Xm increases gradually with added (CTRA)X and almost incrementally with added (TMA)X. However, plots of Xm and H2Om are essentially continuous functions of the aqueous counterion concentration, [Xw], at constant degree of micelle ionization, R. Three factors affect the shapes of these profiles. (a) An initial rapid increase in Xm is attributed to a salt-induced contraction of the micellar interfacial volume. (b) Above ca. 0.1 M [Xw], an incremental (slope of 1) increase in Xm with added counterion for (CTEA)Br, (CTPA)Br, and (CTBA)Br micelles is attributed to free movement counterions and co-ions between the interfacial region of the micelles (up to the micellar core) and the aqueous pseudophase. (c) Xm increases markedly for (CTMA)Br and (CTMA)Cl at their respective sphere-to-rod transitions ca. 0.1 M [Brw] and ca. 1.2 M [Clw]. The increases in Xm are accompanied by concomitant decreases in H2Om. Specific salt-induced rod formation is attributed to dehydration (partial) and tight ion pair formation between surfactant headgroups and counterions. Phase separation of (CTBA)Br micelles in 0.5 M (TMA)Br occurs when the interfacial water concentration is too low to maintain micelle stability. The dependence of Xm on [Xw] contradicts assumptions in the original pseudophase ion exchange model for aggregate effects on chemical reactivity that can be corrected, in part, by setting Xm equal to the sum the aqueous and interfacial counterion concentrations.

Uncoupling proteins (UCPs) are membrane proteins that mediate purine nucleotide-sensitive free fatty acid-activated H(+) flux through the inner mitochondrial membrane. After the discovery of UCP in higher plants in 1995, it was acknowledged that these proteins are widely distributed in eukaryotic organisms. The widespread presence of UCPs in eukaryotes implies that these proteins may have functions other than thermogenesis. In this review, we describe the current knowledge of plant UCPs, including their discovery, biochemical properties, distribution, gene family, gene expression profiles, regulation of gene expression, and evolutionary aspects. Expression analyses and functional studies on the plant UCPs under normal and stressful conditions suggest that UCPs regulate energy metabolism in the cellular responses to stress through regulation of the electrochemical proton potential (Deltamu(H)+) and production of reactive oxygen species.

Purpose: High-risk human papillomavirus (HPV) is the main etiologic factor for cervical cancer.The severity of HPV-associated cervical lesions has been correlated to the number of infiltrating macrophages. The objective of this work is to characterize the role of tumor-associated macrophages (TAM) on the immune cellular response against the tumor. Experimental Design: We used the HPV16 E6-and E7-expressingTC-1mouse tumor model to study the effect ofTAM onT-cell function in vitro, and depletedTAM, using clodronate-containing liposomes, to characterize its role in vivo. Results: TAM, characterized by the positive expression of CD45, F4/80, and CD11b, formed the major population of infiltrating tumor cells. TAM displayed high basal Arginase I activity, producing interleukin-10 (IL-10); they were resistant to iNOSII activity induction, therefore reversion to M1 phenotype, when stimulated in vitro with lipopolysaccharide/IFNg, indicating an M2 phentoype. In cultures of isolated TAM, TAM induced regulatory phenotype, characterized by IL-10 and Foxp3 expression, and inhibited proliferation of CD8 lymphocytes. In vivo, depletion of TAM inhibited tumor growth and stimulated the infiltration of tumors by HPV16 E7 49-57 -specific CD8 lymphocytes, whereas depletion of Gr1 + tumor-associated cells had no effect. Conclusions: M2-like macrophages infiltrate HPV16-associated tumors causing suppression of antitumorT-cell response, thus facilitating tumor growth. Depletion or phenotype alteration of this population should be considered in immunotherapy strategies.

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The cecropin-melittin hybrid antimicrobial peptide BP100 (H-KKLFKKILKYL-NH2) is selective for Gram-negative bacteria, negatively charged membranes, and weakly hemolytic. We studied BP100 conformational and functional properties upon interaction with large unilamellar vesicles, LUVs, and giant unilamellar vesicles, GUVs, containing variable proportions of phosphatidylcholine (PC) and negatively charged phosphatidylglycerol (PG). CD and NMR spectra showed that upon binding to PG-containing LUVs BP100 acquires α-helical conformation, the helix spanning residues 3-11. Theoretical analyses indicated that the helix is amphipathic and surface-seeking. CD and dynamic light scattering data evinced peptide and/or vesicle aggregation, modulated by peptide:lipid ratio and PG content. BP100 decreased the absolute value of the zeta potential (ζ) of LUVs with low PG contents; for higher PG, binding was analyzed as an ion-exchange process. At high salt, BP100-induced LUVS leakage requires higher peptide concentration, indicating that both electrostatic and hydrophobic interactions contribute to peptide binding. While a gradual release took place at low peptide:lipid ratios, instantaneous loss occurred at high ratios, suggesting vesicle disruption. Optical microscopy of GUVs confirmed BP100-promoted disruption of negatively charged membranes. The mechanism of action of BP100 is determined by both peptide:lipid ratio and negatively charged lipid content. While gradual release results from membrane perturbation by a small number of peptide molecules giving rise to changes in acyl chain packing, lipid clustering (leading to membrane defects), and/or membrane thinning, membrane disruption results from a sequence of events - large-scale peptide and lipid clustering, giving rise to peptide-lipid patches that eventually would leave the membrane in a carpet-like mechanism.