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In Vitro Surfactant Structure-Toxicity Relationships: Implications for Surfacta...
Inácio, Ângela S.; Mesquita, Katia A.; Baptista, Marta; Ramalho-Santos, João; Vaz, Winchil L. C.; Vieira, Otília V.Background The need for woman-controlled, cheap, safe, effective, easy-to-use and easy-to-store topical applications for prophylaxis against sexually transmitted infections (STIs) makes surfactant-containing formulations an interesting option that requires a more fundamental knowledge concerning surfactant toxicology and structure-activity relationships. Methodology/Principal Findings We report in vitro effect...
In vitro surfactant structure-toxicity relationships: implications for surfacta...
Inácio, Ângela S; Mesquita, Katia A; Jordão, Luísa; Santos, Maria S; Moreno, António J M; Vaz, Winchil L C; Vieira, Otília VSexually transmitted infections (STIs) are a major public-health problem worldwide. According to the World Health Organization there are 340 million new cases of bacterial and protozoal STIs (Gonorrhea, Syphilis, Chlamydia and Trichomoniasis) per year. The direct treatment costs and serious perinatal collateral damage caused by STIs represent hefty financial and social burdens, particularly in developing countr...
Surfactants as microbicides and contraceptive agents: a systematic in vitro study
Vieira, Otilia V.; Hartmann, Diego O.; Cardoso, Carla M. P.; Oberdoerfer, Daniel; Baptista, Marta; Santos, Manuel A. S.; Almeida, LuisBackground: The urgent need for cheap and easy-to-use protection against both unwanted pregnancies and sexually transmitted diseases has stimulated considerable interest in the use of surfactants as microbicides, anti-viral, and contraceptive agents in recent years. In the present study we report a systematic in vitro evaluation of the microbicidal, anti- viral and contraceptive potential of cationic, anionic, ...
Model systems, lipid rafts, and cell membranes
Simons, Kai; Vaz, Winchil L. C.Views of how cell membranes are organized are presently changing. The lipid bilayer that constitutes these membranes is no longer understood to be a homogeneous fluid. Instead, lipid assemblies, termed rafts, have been introduced to provide fluid platforms that segregate membrane components and dynamically compartmentalize membranes. These assemblies are thought to be composed mainly of sphingolipids and choles...
Solubility of amphiphiles in membranes: influence of phase properties and amphi...
Estronca, Luís M. B. B.; João Moreno, Maria; Abreu, Magda S. C.; Melo, Eurico; Vaz, Winchil L. C.http://www.sciencedirect.com/science/article/B6WBK-46H83R0-H/1/cf7e21f8fbce89b98d2bc5c02a37fdbd
Fluorescence Spectroscopic Studies on Phase Heterogeneity in Lipid Bilayer Memb...
Vaz, Winchil L. C.; Melo, EuricoThere is a growing interest in functional membrane heterogeneity on the mesoscopic (several tens to hundreds of molecular dimensions) scale. However, the physical-chemical basis for this sort of heterogeneity in membranes is not entirely clear. Unambiguous methods to demonstrate that the cell plasma membrane and other cellular membranes are in fact heterogeneous on the mesoscopic level are also not generally av...
Effect of short-chain primary alcohols on fluidity and activity of sarcoplasmic...
Almeida, Leonor M.; Vaz, Winchil L. C.; Stuempel, Juergen; Madeira, Vitor M. C.Intramolecular excimer formation with the fluorescent probe 1,3-di( 1 -pyrenyl)propane, differential scanning calorimetry, and X-ray diffraction were used to assess the effect of ethanol, 1-butanol, and 1-hexanol on the bilayer organization in model membranes, sarcoplasmic reticulum (SR) lipids and native SR membranes. These alcohols have fluidizing effects on membranes and lower the main transition temperature...
Modulation of sarcoplasmic reticulum calcium pump activity by membrane fluidity
Almeida, Leonor M.; Vaz, Winchil L. C.; Zachariasse, Klaas A.; Madeira, Vitor M. C.Intramolecular excimerization of 1,3-di- l-pyrenylpropane [Py(3)Py] was used to assess the fluidity of sarcoplasmic reticulum membranes (SR); on the basis of the spectral data, the probe incorporates completely inside the membrane probably somewhere close to the polar head groups of phospholipid molecules, however not in the very hydrophobic core. The excimerization rate is very sensitive to lipid phase transit...
Size dependence of the translational diffusion of large integral membrane prote...
Vaz, Winchil L. C.; Criado, Manuel; Madeira, Vitor M. C.; Schoellmann, Guenther; Jovin, Thomas M.The translational diffusion of bovine rhodopsin, the Caz+-activated adenosinetriphosphatase of rabbit muscle sarcoplasmic reticulum, and the acetylcholine receptor monomer of Torpedo marmorata has been examined at a high dilution (molar ratios of lipid/protein 1 3000/1) in liquidcrystalline phase phospholipid bilayer membranes by using the fluorescence recovery after photobleaching technique. These integral mem...
Fluidity of sarcoplasmic reticulum membranes investigated with dipyrenylpropane...
Almeida, Leonor M.; Vaz, Winchil L. C.; Zachariasse, Klaas A.; Madeira, Vitor M. C.Intramolecular excimer formation with 1,3-di( 1 - pyreny1)propane was used to probe the fluidity of sarcoplasmic reticulum (SR) membranes where the probe could be incorporated (in a probe/lipid molar ratio of 1/2OOO or less) without inducing any detectable damage. The temperature was varied between -1 and 40 'C. The fluidity of the native SR membrane changes from 52 CP at 40 OC to 325 CP at 5 'C. The native SR ...
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