Proton flux across artificial vesicle bilayers

The study of proton conductance across artificial membranes has revealed a surprisingly high permeability for H+, (Pnet H+). A high Pnet H+ is difficult to reconcile with the biological requirement for the maintenance of pH gradients across the plasma membranes of cells, organellar study was undertaken to examine the role played by cholesterol and phospholipid fatty acid side chain composition in determining how well a membrane will function as a barrier to acid. The effects of counter-ion movement on acidification rates were examined in order to interpret the data obtained from variations in membrane composition. In phosphate buffered saline solutions, vesicle membranes composed of unsaturated fatty acid phosphatidylcholines proved to be poorer barriers to acid than membranes composed of saturated fatty acids. The barrier properties of these membranes could be ranked in the following order: DPL, (palmitic) $>$ Egg PC, (mixed chains) $>$ DLL, (linoleic), with DPL being the most effective in maintaining a one pH unit gradient near neutrality. Cholesterol decreased acidification rates of membranes made from the unsaturated phosphatidylcholines Egg PC and DLL, but enhanced acidification rates in vesicle membranes composed of the saturated phospholipid DPL. The cholesterol and fatty acid side chain effects were mediated by changes in membrane fluidity, with more rigid bilayers forming better barriers to acid. Experimental evidence was obtained which confirmed the Pnet H+ is very high relative to the permeabilities of other ions. Counter-ion controlled acidification rates depended on the size and charge of the ion which was moving in order to maintain electroneutrality. The biological relevance of a high intrinsic Pnet H+ and the possible role of counter-ion controlled acidification were discussed. ^

The effects of omega -3 fatty acid -enriched fish on C -reactive protein levels in postmenopausal women

Coronary heart disease (CHD) is the leading cause of death in women and rates markedly increase among women after 65 years of age. C-reactive protein (CRP) is a new clinical indicator of atherosclerotic-related inflammation with a direct pathogenic role. Studies show lifestyle factors can modulate CRP. Omega-3 fatty acids have anti-inflammatory properties and studies suggest that eating fish high in omega-3 fatty acids may lower CHD risk in women. This study sought to assess the possible role of omega-3 fatty acids in the reduction of CHD-related inflammation by investigating the effect of fish consumption on CRP levels. Methods. Twenty-four healthy postmenopausal women were randomly assigned to a fish group (usual diet plus two servings per week of enriched fish) or control group (usual diet with no fatty fish) for eight weeks. Omega-3 fatty acid-enriched fish developed by the West Virginia University Aquaculture Division was used. Serum CRP, serum interleukin-6 (IL-6), and the fatty acid content of red blood cells (RBC) were measured before and after the study. Women also completed food records. RESULTS: Baseline levels of CRP were low (85% of the fish group had normal levels) and few changes in CRP risk category were observed. Mean IL-6 levels were reduced by 27% and 35% in the fish and control groups, respectively (p for between-group difference = 0.60). Changes in RBC fatty acid composition were not statistically significant. Compared to control women, women in the fish group had greater reductions in mean triglycerides (p = 0.08), total cholesterol (P = 0.04), and LDL cholesterol levels (p = 0.06). Baseline dietary intake of total and monounsaturated fatty acids tended to be positively associated with baseline CRP, while vitamin E intake was inversely related. Saturated fat intake tended to have a positive association with IL-6. Conclusions. Findings regarding the effect of two servings of fish on CRP and IL-6 levels are inconclusive due to low baseline levels of CRP and IL-6. However, results indicate two servings of fatty fish have favorable effects on blood lipids. The relationship of dietary components with CRP and IL-6 is complex and further research is needed to determine the varying roles of diet on the inflammatory process. ^