A DMPA Langmuir monolayer study: from gas to solid phase. An atomistic description by molecular dynamics Simulation.

In this work, a DMPA Langmuir monolayer at the air/water interface was studied by molecular dynamics simulations. Thus, an atomistic picture of a Langmuir monolayer was drawn from its expanded gas phase to its final solid condensed one. In this sense, some properties of monolayers that were traditionally poorly or even not reproduced in computer simulations, such as lipid domain formation or pressure-area per lipid isotherm, were properly reproduced in this work. Thus, the physical laws that control the lipid domain formation in the gas phase and the structure of lipid monolayers from the gas to solid condensed phase were studied. Thanks to the atomistic information provided by the molecular dynamics simulations, we were able to add valuable information to the experimental description of these processes and to access experimental data related to the lipid monolayers in their expanded phase, which is difficult or inaccessible to study by experimental techniques. In this sense, properties such as lipids head hydration and lipid structure were studied.

Antithrombotic potential of olive oil administration in rabbits with elevated cholesterol.

Olive oil is the main source of dietary fatty acids in the Mediterranean region. The objective of this study was to evaluate the effect of dietary supplementation with virgin olive oil in an experimental model with rabbits fed an atherogenic diet (saturated fat 48% of total fat). Four different groups of 10 animals each were studied: (1) normolipemic diet (NLD), (2) atherogenic diet or saturated fatty acid-enriched diet (SFAED), (3) NLD with 15% olive oil (NLD+OLIV), and (4) SFAED with 15% virgin olive oil (SFAED+OLIV). The animals were fed the experimental diets for 6 weeks, after which we determined serum lipid profile (total cholesterol, HDL-cholesterol, and triglycerides), platelet aggregation, platelet thromboxane B(2), aortic prostacyclin, and platelet and vascular lipid peroxidation. Scanning electron microscopic images of the vascular endothelium were studied, as were morphometric parameters in the arterial wall and thrombogenicity of the subendothelium (annular perfusion chamber). Animals fed the SFAED showed platelet hyperactivity and increased subendothelial thrombogenicity. Animals fed the SFAED+OLIV showed, compared with the SFAED group, an improved lipid profile with decreased platelet hyperactivity and subendothelial thrombogenicity and less severe morphological lesions of the endothelium and vascular wall. We conclude that supplementation of the SFAED with 15% olive oil reduced vascular thrombogenicity and platelet activation in rabbits. Although the percentage of olive oil in the diet was higher than the amount in the human diet, these results may be helpful in determining the effect of olive oil in the human thrombogenic system.

Effect of dietary supplementation with evening primrose oil on vascular thrombogenesis in hyperlipemic rabbits.

The dietary intake of saturated fatty acids affects arteriosclerosis. We studied the effect of supplementation (15% wt/wt) of a hyperlipemic diet (1.3% cholesterol) with evening primrose oil (Oenothera biennis) in four groups of 10 rabbits each. After 6 weeks the aortic endothelium was analyzed morphologically with scanning electron microscopy, and the arterial wall was studied with morphometric techniques and cell nucleus counts. Endothelial functioning was analyzed by measuring prostacyclin synthesis, and thrombogenicity of the subendothelium was studied by perfusion in a Baumgartner annular chamber. Evening primrose oil reduced hypercholesterolemia (from 29 +/- 3 to 12 +/- 2 nmol/l), increased HDL-cholesterol (from 0.5 +/- 0.06 to 0.8 +/- 0.09 nmol/l) and doubled prostacyclin synthesis (from 2.7 +/- 2 to 6.2 +/- 0.7 ng/mg aorta) in rabbits on the hyperlipemic diet, reduced subendothelial surface occupied by platelets (from 6.9 +/- 0.4 to 4.8 +/- 0.3%), and reduced human platelet adhesion on the subendothelium (from 53.3 +/- 6% to 38 +/- 8%, respect to total occupation). Morphological analyses showed that evening primrose oil diminished endothelial lesions caused by the atherogenic diet, reducing area of the arterial wall (from 6.9 +/- 0.2 to 4.7 +/- 0.2 microm2 x 10(6)) and the degree of neointimal proliferation (from 0.6 +/- 0.02 to 0.4 +/- 0.09 microm2 x 10(6)). We conclude that in our experimental model, this dietary supplement enhanced the antithrombotic capacity of the endothelium, reduced subendothelial thrombogenicity, and diminished the extent of vascular wall lesions caused by the hyperlipemic diet.

Effect of evening primrose oil on platelet aggregation in rabbits fed an atherogenic diet.

Evening primrose oil (Oenothera biennis) is a rich source of omega-6 series fatty acids. We report here the effects of dietary supplementation with evening primrose oil (EPO) on platelet aggregation as the main factor in arterial thrombus formation in an experimental model of atherogenesis in rabbits. A total of 40 male white New Zealand rabbits were divided into four groups (n = 10 animals/group): 1: normal diet, 2: atherogenic diet (ATD), 3: normal diet enriched with 15% EPO, 4: ATD + EPO. Each group was kept on the diet for 6 weeks. We determined serum lipid profile, platelet aggregation in whole blood, platelet thromboxane B2 production and platelet lipid peroxides. The atherogenic diet increased platelet aggregation (135% when ADP was used, and 185% when collagen was used as the inducer). Evening primrose oil reduced hyperaggregation to the values obtained in rabbits fed with the normal diet. Thromboxane synthesis was increased from 0.18 to 2.28 nmol/10(9) platelets); EPO reduced this value to 1.38 nmol/10(9) platelets. Lipid peroxides were increased by ATD from 0.27 to 0.81 nmol/10(8) platelets; EPO prevented this increase (0.35 nmol/10(8) platelets). In conclusion, EPO reduced platelet hyperaggregability in rabbits fed an atherogenic diet.