Fully Crystalline Faceted Fe-Au Core-Shell Nanoparticles.

Fe-Au core-shell nanoparticles displaying an original polyhedral morphology have been successfully synthesized through a physical route. Analyses using transmission electron microscopy show that the Au shell forms truncated pyramids epitaxially grown on the (100) facets of the iron cubic core. The evolution of the elastic energy and strain field in the nanoparticles as a function of their geometry and composition is calculated using the finite-element method. The stability of the remarkable centered core-shell morphology experimentally observed is attributed to the weak elastic energy resulting from the low misfit at the Fe/Au (100) interface compared to the surface energy contribution.

Elementary mechanisms of shear-coupled grain boundary migration.

A detailed theoretical study of the elementary mechanisms occurring during the shear-coupled grain boundary (GB) migration at low temperature is performed focusing on both the energetic and structural characteristics. The migration of a Σ13(320) GB in a copper bicrystal in response to external shear displacements is simulated using a semiempirical potential. The minimum energy path of the shear-coupled GB migration is computed using the nudge elastic band method. The GB migration occurs through the nucleation and motion of GB steps identified as disconnections. Energy barriers for the GB and disconnection migrations are evaluated.

Preferential incorporation of dietary cis-9,cis-12,trans-15 18:3 acid into rat cardiolipins.

Cardiolipins from mitochondria of different rat organs (heart; liver and kidney) appear to be privileged targets for the incorporation of cis-9,cis-12,trans-15 18:3 acid, a compound commonly found in deodorized edible linolenic acid-containing oils. When this acid (together with other linolenic acid geometrical isomers (LAGI)) is fed at high load to rats that had been reared on a fat-free diet since weaned for a few days, it replaces the endogenously synthesized monoenoic acids that had accumulated in cardiolipin during fat deficiency. Although there is no discrimination in deposition of any LAGI in adipose tissue triacylglycerols, a high selectivity of incorporation of the cis-9,cis-12,trans-15 18:3 acid over other isomers (including the all-cis 18:3(n-3) acid) is observed either in diradylphospholipids or in cardiolipins. However, cis-9,cis-12,trans-15 18:3 acid accumulates in cardiolipins at a considerably higher level than in other phospholipids (11 times in liver, 5-7 times in heart and kidney). It reaches 22-24% of total fatty acids in cardiolipins from heart and liver, and 13-14% in kidney. The cis-9,cis-12,trans-15 18:3 acid is esterified to both the 1(1")- and 2(2")-positions of liver mitochondria cardiolipin, with a well-marked selectivity for positions 1(1"). Its 1(1")/2(2") selectivity ratio is about the same as that of 18:2(n-6) acid: 2.1 vs 2.2. It is concluded that the trans-15 ethylenic bond is probably perceived as a single bond by enzymic systems that ensure acylation of cardiolipins. The cis-9,cis-12,trans-15 isomer is able to reverse the fatty acid modifications induced in cardiolipins by a diet devoid of essential fatty acids, in a way similar to that of 18:2(n-6) acid supplementation.

Changing shapes in the nanoworld

What are the mechanisms leading to the shape relaxation of three-dimensional crystallites? Kinetic Monte Carlo simulations of fcc clusters show that the usual theories of equilibration, via atomic surface diffusion driven by curvature, are verified only at high temperatures. Below the roughening temperature, the relaxation is much slower, kinetics being governed by the nucleation of a critical germ on a facet. We show that the energy barrier for this step linearly increases with the size of the crystallite, leading to an exponential dependence of the relaxation time.

Effects of preterm infant formula supplementation with alpha-linolenic acid with a linoleate/alpha-linolenate ratio of 6: a multicentric study.

OBJECTIVE: To investigate the effects of a milk formula supplemented with a alpha-linolenic acid (ALA) (18:2 n-6/18:3 n-3 ratio near 6/1) on plasma and red blood cell (RBC) fatty acids (FAs) in premature infants and compare with a non supplemented formula (18:2 n-6/18:3 n-3 = 22/1). DESIGN AND SUBJECTS: Infants of mothers who elected not to breast-feed were randomly assigned to either a high alpha linolenic formula (HLF: n = 31) group or a low alpha-linolenic formula (LLF: n = 32) control group. Infants fed human milk (HM: n = 25) were enrolled concurrently as a reference group. Anthropometric and biological measurements were made after two days (D2) and 15 d (D15) of enteral feeding and at the 37th week (W37) of postconceptual age. In HLF, the 18:3 n-3 content was 1.95% of total FAs (0.77% of total energy) and the 18:2 n-6/18:3 n-3 ratio was near 6/1. In LLF, the 18:3 n-3 content was 0.55% of total FAs (0.22% of total energy) and the 18:2 n-6/18:3 n-3 ratio was 22/1. RESULTS: ALA supplementation had minimal effect on the n-6 series, did not alter the anthropometric data and confirmed the conversion of ALA into docosahexaenoic acid (DHA). Throughout the study, it maintained, the RBC membrane DHA values within the confidence interval of those obtained in the HM group. Such was not the case with LLF CONCLUSION: alpha-linolenic acid supplementation (from Rapeseed oil and in a 18:2 n-6/18:3 n-3 ratio = 6) in premature infant formula can contribute efficiently to the maintenance of the n-3 status in the premature newborns.

Positional distribution of fatty acids in cardiolipin of mitochondria from 21-day-old rats.

Pure cardiolipins (1,3-diphosphatidylglycerol) were prepared from mitochondria of heart, liver and kidney from 21-day-old male Wistar rats and submitted to Naja naja venom phospholipase A2 (EC 3.1.1.4) action. Incubation conditions were controlled carefully, and a complete hydrolysis of cardiolipin to lysocardiolipin (di [1 (1'') acyl sn-glycero-3-phosphoryl] 1',3'-sn-glycerol) and fatty acids from positions 2(2'') was obtained in less than two hr practically without side reactions. Cardiolipins from the three organs contained low levels of saturated fatty acids; stearic acid accounted for 0.4-0.7% and palmitic acid for 1.4-3.5% of total fatty acids. These percentages apparently depended on the organ. In all three cases, linoleic acid was the major component, but its percentage varied from 62-78% of total fatty acids. Acyl chains linked to positions 1 (1'') of all three cardiolipin preparations exhibited a similar pattern: they were composed of linoleic acid for 85-89%. This fatty acid also was the main component esterified at position 2 (2''), but its percentage was much more variable: from 39.8% in heart to 51.2% in kidney and 67.8% in liver mitochondria. The remaining acids comprised octadecenoic and polyunsaturated fatty acids with more than 18 carbon atoms in different proportions. As opposed to other phospholipids, cis-vaccenic acid, and not oleic acid, was the main octadecenoic acid present in cardiolipins. Octadecenoic acids were nine- to 10-fold more concentrated at positions 2 (2'') than at positions 1 (1''). The percentage of cis-vaccenic acid was four- to five-fold higher than that of oleic acid at positions 2 (2''), whereas oleic acid dominated at positions 1 (1'').(ABSTRACT TRUNCATED AT 250 WORDS)

Incorporation of alpha-tocopherol in marine lipid-based liposomes: in vitro and in vivo studies.

Liposomes made from a natural marine lipid extract and containing a high polyunsaturated n-3 fatty lipid ratio were envisaged as oral route vectors and a potential alpha-tocopherol supplement. The behavior of vesicles obtained by simple filtration and of giant vesicles prepared by electroformation was investigated in gastrointestinal-like conditions. The influence of alpha-tocopherol incorporation into liposomes was studied on both physical and chemical membrane stability. Propanal, as an oxidation product of n-3 polyunsaturated fatty acids, was quantified by static headspace gas chromatography when alpha-tocopherol incorporation into liposome ratios ranged from 0.01 to 12 mol%. Best oxidative stability was obtained for liposomes that contained 5 mol% alpha-tocopherol. Compared to the other formulas, propanal formation was reduced, and time of the oxidation induction phase was longer. Moreover, alpha-tocopherol induced both liposome structural modifications, evidenced by turbidity, and phospholipid chemical hydrolysis, quantified as the amount of lysophospholipids. This physicochemical liposome instability was even more pronounced in acid storage conditions, i.e., alpha-tocopherol incorporation into liposome membranes accelerated the structural rearrangements and increased the rate of phospholipid hydrolysis. In particular, giant vesicles incubated at pH 1.5 underwent complex irreversible shape transformations including invaginations. In parallel, the absorption rate of alpha-tocopherol was measured in lymph-cannulated rats when alpha-tocopherol was administrated, as liposome suspension or added to sardine oil, through a gastrostomy tube. Alpha-tocopherol recovery in lymph was increased by almost threefold, following liposome administration. This may be related to phospholipids that should favor alpha-tocopherol solubilization and to liposome instability in the case of a high amount of alpha-tocopherol in the membranes. A need to correlate results obtained from in vitro liposome behavior with in vivo lipid absorption was demonstrated by this study.

Modification of alkenyl chain profile in plasmalogens of rat heart mitochondria by dietary trielaidin.

Effects of dietary trielaidin upon the alkenyl chain profile of plasmalogens were studied using heart mitochondria of rats fed a semi-purified diet containing 10% of fat supplement in which elaidic acid accounted for 69% of total fatty acids. Alkyl substituted dioxane (ASD) derivatives of the alkenyl groups of plasmalogens were prepared and analyzed by silver nitrate TLC and by GLC on different phases (BDS and OV-275). After two months of feeding the experimental diet, 40% of the ASD contained a trans-octadecenyl chain, suggesting that dietary elaidic acid was reduced in vivo to the corresponding alcohol and incorporated into plasmalogens. There was a simultaneous decrease in the percentage of ASD containing saturated chains, but the percentage of ASD substituted with cis-octadecenyl chains was not significantly affected. These observations suggested that elaidic acid may compete with saturated fatty acids, but not with cis-octadecenoic acids during the plasmalogen biosynthesis. Feeding trielaidin did not seem to have any significant influence on the relative proportions of plasmalogens, which accounted for 11-12%, on a phosphorus basis, of total heart mitochondria phospholipids.

Lymphatic absorption of nonvolatile oxidation products of heated oils in the rat.

The lymphatic absorption of nonvolatile oxidation products (NVOP) formed during heating of fats was studied. Heated colza or soybean oils or synthetic triglycerides containing a definite aromatic or alicyclic fatty acid were fed to thoracic duct-cannulated rats. Tritium-labeled triolein was added to each dietary fat, as an internal standard, in order to calculate the percentage of lymphatic absorption of the ingested NVOP. Results show that 4% of the total polymeric acids, 53% of the total oxidized monomeric acids and 96% of the total cyclic monomeric acids were recovered in the lymphatic lipids. Gas liquid and quantitative thin layer chromatography of these 3 classes indicated that, within a NVOP class, the various constituents did not present the same absorption rate. The lymphatic absorptions of individual oxidized monomers were between 25 and 93%. Concerning the polymer fraction, the lymphatic recoveries were 1% (nonpolar dimers), 6.8% (polar dimers) and 12% (polar oligomers). Aromatic acids were absorbed to a lesser degree (50-60%) than cyclohexenic acids (91-98%).

Follow-up of the delta4 to delta16 trans-18:1 isomer profile and content in French processed foods containing partially hydrogenated vegetable oils during the period 1995-1999. Analytical and nutritional implications.

A survey of the total content of trans-18:1 acids and their detailed profile in French food lipids was conducted in 1995-1996, and 1999. For this purpose, 37 food items were chosen from their label indicating the presence of partially hydrogenated vegetable oils (PHVO) in their ingredients. The content as well as the detailed profile of these isomers was established by a combination of argentation thin-layer chromatography and gas liquid chromatography (GLC) on long polar capillary columns. With regard to the mean trans-18:1 acid contents of extracted PHVO, a significant decrease was observed between the two periods, i.e., from 26.9 to 11.8% of total fatty acids. However, only minor differences were noted in the mean relative distribution profiles of individual trans-18:1 isomers with ethylenic bonds between positions delta4 and delta16 for the two periods. The predominant isomer was delta9-18:1 (elaidic) acid, in the wide range 15.2-46.1% (mean, 27.9+/-7.2%) of total trans-18:1 acids, with the delta10 isomer ranked second, with a mean of 21.3% (range, 11.6 to 27.4%). The content of the unresolved delta6 to delta8 isomer group was higher than the delta11 isomer (vaccenic acid), representing on average 17.5 and 13.3%, respectively. Other isomers delta4, delta5, delta12, delta13/delta14, delta15, and delta16, were less than 10% each: 1.0, 1.6, 7.4, 7.1, 1.8, and 1.0%, respectively. However, considering individual food items, it was noted that none of the extracted PHVO were identical to one another, indicating a considerable diversity of such fats available to the food industry. A comparison of data for French foods with similar data recently established for Germany indicates that no gross differences occur in PHVO used by food industries in both countries. Estimates for the absolute mean consumption of individual isomers from ruminant fats and PHVO are made for the French population and compared to similarly reconstructed hypothetical profiles for Germany and North America. Differences occur in the total intake of trans-18:1 acids, but most important, in individual trans-18:1 isomer intake, with a particular increase of the delta6-delta8 to delta10 isomers with increasing consumption of PHVO. It is inferred from the present and earlier data that direct GLC of fatty acids is a faulty procedure that results (i) in variable underestimates of total trans-18:1 acids, (ii) in a loss of information as regards the assessment of individual isomeric trans-18:1 acids, and (iii) in the impossibility of comparing data obtained from human tissues if the relative contribution of dietary PHVO and ruminant fats is not known.

Trans fatty acids in adipose tissue of French women in relation to their dietary sources.

This study reports the fatty acid composition of subcutaneous adipose tissue in French women with special emphasis on the content of trans fatty acids originating from two main dietary sources, ruminant fats and partially hydrogenated vegetable oils (PHVO). Adipose tissue trans fatty acid levels from 71 women, recruited between 1997 and 1998, were determined using a combination of capillary gas chromatography and silver nitrate thin-layer chromatography. Results indicate that on average cis monounsaturates accounted for 47.9% of total fatty acids, saturates for 32.2%, and linoleic acid for 14.4%. Cis n-3 polyunsaturates represented only 0.7%. Total content of trans fatty acids was 2.32 +/- 0.50%, consisting of trans 18:1 (1.97 +/- 0.49%), trans 18:2 (0.28 +/- 0.08%), and trans 16:1 (0.06 +/- 0.03%). Trans 18:3 isomers were not detectable. The level of trans fatty acids found in adipose tissue of French women was lower than those reported for Canada, the United States, and Northern European countries but higher than that determined in Spain. Therefore, trans fatty acid consumption in France appears to be intermediate between that of the United States or North Europe and that of Spain. Based on the equation of Enig et al., we estimated the mean daily trans 18:1 acid intake of French women at 1.9 g per person. The major trans 18:1 isomer in adipose tissue was delta11 trans, as in ruminant fats. Estimates of relative contribution of trans fatty acid intake were 55% from ruminant fats and 45% from PHVO. This pattern contrasts sharply with those established for Canada and the United States where PHVO is reported to be the major dietary source of trans fatty acids.

Differential impact of milk fatty acid profiles on cardiovascular risk biomarkers in healthy men and women.

BACKGROUND/OBJECTIVES: The objective of this study was to evaluate the impact of three specific ruminant (R) milk fats resulting from modification of the cow's diet on cardiovascular risk factors in healthy volunteers. R-milk fats were characterized by increased content in total trans fatty acids (R-TFAs) and parallel decrease in saturated fatty acids (SFAs). SUBJECTS/METHODS: A total of 111 healthy, normolipemic men and women have been recruited for a monocentric, randomized, double-blind and parallel intervention, 4-week controlled study. Volunteers consumed three experimental products (butter, dessert cream and cookies) made with one of the three specific milk fats (55 g fat per day). During the first week (run-in period), the subjects consumed on a daily basis dairy products containing 72% SFA/2.85% R-TFA (called 'L0'). For the next 3 weeks of the study (intervention period), the first group continued to consume L0 products. The second group received dairy products containing 63.3% SFA/4.06% R-TFA (called 'L4'), and the third group received dairy products containing 56.6% SFA/12.16% R-TFA (called 'L9'). RESULTS: Plasma concentrations of high-density lipoprotein (HDL)-cholesterol were not significantly altered by either diet (P=0.38). Compared to L0 diet, L4 diet contributed to reduce low-density lipoprotein (LDL)-cholesterol (-0.14+/-0.38 mmol/l, P=0.04), total cholesterol (-0.13+/-0.50 mmol/l, P=0.04), LDL-cholesterol/HDL-cholesterol (-0.14+/-0.36, P=0.03) and total cholesterol/HDL-cholesterol (-0.18+/-0.44, P=0.02). CONCLUSIONS: Different milk fat profiles can change cardiovascular plasma parameters in human healthy volunteers. A limited increase of the R-TFA/SFA ratio in dairy products is associated with an improvement in some cardiovascular risk factors. However, a further increase in R-TFA/SFA ratio has no additional benefit.

[Implications of the incorporation of transisomers of unsaturated fatty acids into cell membranes]. / Implications de l'incorporation d'isomeres trans d'acides gras insaturés au niveau des membranes cellulaires.

The incorporation of dietary trans fatty acids is shown into intestinal brush border and heart mitochondrial membranes obtained from rats fed with either partially hydrogenated soybean oil or with a synthetic triglyceride containing elaidic or linelaidic acid. The distribution of dietary linelaidate in the major phospholipid classes from inner membranes of mitochondria is determined. Heart mitochondria from normal rats and linelaidic acid fed rats are compared with respect to their swelling rate and their oxidative phosphorylation. The influence of dietary linelaidate on the activity of some brush border-associated enzymes is also studied. On the basis of the authors' observations and those made by others with microorganism cels or models of biological membranes (liposomes and monomolecular films), the possible implications of trans fatty acids incorporation on membrane functions are reviewed.

[Time-course changes in the alkenyl and acyl chain composition of plasmalogens from the heart and kidneys of rats ingesting trielaidin]. / Evolution au cours du temps de la composition en chaînes alkényles et acyles des plasmalogènes de mitochondries de coeur et de reins chez des rats ingérant de la triélaïdine.

Weaned rats were fed for 7 or 32 days a semi-purified diet containing 10% of fat supplement in which elaidic acid accounted for 64.5% of total fatty acids. Alkenyl groups from plasmalogens of kidney and heart mitochondria were analysed as their alkyl-substituted dioxane derivatives by gas liquid chromatography (GLC). Acyl chains of total and individual phospholipids (phosphatidylcholine: PC; phosphatidylethanolamine: PE, diacyl and alkenyl-acyl forms; phosphatidylinositol: PI; cardiolipin: CL) were also analysed by GLC. Maximum level of elaidic acid incorporation was attained after only one week on the experimental diet in either total or individual phospholipids. Heart mitochondria phospholipids contained about 40% more trans-monounsaturated acids (20.9%) than kidney mitochondria phospholipids (12.5%) after one month. trans-Monounsaturated acids (t-18: 1 plus t-16: 1 acids) were incorporated in individual phospholipids from both organs in decreasing order: PI greater than PE (total) greater than PC much greater than CL. The order of incorporation of elaidic acid seemed to be related to the content of stearic acid in these phospholipids when the diet was devoid of elaidic acid (PI greater than PE greater than PC much greater than CL). The content of elaidic acid in alkenyl-acyl-glycerophosphoethanolamine (alkenyl-acyl-GPE) was the same (6% of total fatty acids) in both organs. The time-course incorporation of trans-monounsaturated alkenyl chains was different. After one week on the elaidic acid-enriched diet, they represented only 65% (kidney) or 43% (heart) of the values reached after one month. At the end of the feeding period, the trans-monounsaturated alkenyl chains were also about 40% less in total plasmalogens from kidney mitochondria (27.8%) than from heart mitochondria (46%). trans-Monounsaturated acyl chains were incorporated at a higher rate in the 2-position of alkenyl-acyl-GPE than trans-monounsaturated alkenyl chains in their 1-position. Our results confirm the unique observation of Kramer et al. (1985) who noticed that the fatty acid composition of phospholipids was much more rapidly equilibrated than the alkenyl chain composition of plasmalogens (1 week vs 2-3 weeks) from heart of rats fed diets supplemented with different oils.

Effects on cholesterol balance and LDL cholesterol in the rat of a soft-ripened cheese containing vegetable oils.

OBJECTIVE: The purpose of this study was to examine effects of a modified soft-ripened cheese containing vegetable oils on cholesterol status, using the rat as the experimental model and the traditional soft-ripened cheese as the control. METHODS: Adult male Wistar rats (approximately 370 g) were divided into two dietary groups (20 rats/group) and fed either the standard diet (STD, containing traditional cheeses made from whole milk) or the experimental diet (EXP, containing modified cheeses made from the combination of skim milk with the following fat mixture: milk fat/oleic acid-enriched sunflower oil/soybean oil mixture). Lipids of the diets came solely from cheeses (14 g/100 g diet); the EXP diet contained (3-fold) less saturated fat, (2-fold) less cholesterol, and (15-fold) more phytosterols than the STD diet. RESULTS: Although serum triglyceride and total cholesterol concentrations were not affected by the type of diet, the EXP diet resulted in a significant reduction of LDL-cholesterol (31%, p < 0.001) and a significant increase of HDL-cholesterol (11%, p < 0.05), compared to the STD diet. Thus, a marked reduction (39%) of serum LDL/HDL cholesterol ratio was observed in the EXP group (p < 0.001). In addition, the two quantitative balances (excreted/ingested) of cholesterol and total neutral sterols (for which phytosterols were excluded) were significantly higher by 183% and 174%, respectively for the EXP group, compared to the STD group (p < 0.05). On another hand, rats fed the EXP diet excreted more cholesterol than they ingested dietary cholesterol (cholesterol balance > 1), indicating that those animals eliminated some endogenous cholesterol in their feces, while the opposite was true for rats fed the STD diet (cholesterol balance < 1). Finally, fecal bile salt concentration was not significantly different between the two dietary groups. CONCLUSIONS: The partial substitution of milk fat by vegetable oils in soft-ripened cheese resulted in a decreased blood LDL/HDL cholesterol ratio and an increased fecal excretion of endogenous cholesterol and neutral sterols and, thus, markedly improved its nutritional qualities. Therefore, the consumption of the described modified cheese may meet the demand of subjects who wish to lower their risk for atherosclerosis and cardiovascular disease.

Longitudinal multicentric study of plasma and red blood cell fatty acids and lipids in preterm newborns fed human milk.

The present multicentric study (three centers) deals with the values of plasma and red blood cell fatty acids obtained in a group of 18 preterm newborns after 2 days (D2), 15 days (D15) and 5 weeks (37th week postconception: 37th wk) of human milk feeding. Analytical methods were randomized between the three centers and quality control was evaluated by repeated analysis of reference samples. 20:4 n-6 varied from 10.71 +/- 1.58% to 9.51 +/- 1.65 and 10.10 +/- 1.42% in plasma phospholipids and from 16.59 +/- 3.30% to 14.68 +/- 3.14 and 18.24 +/- 4.09% in red blood cell phosphatidylethanolamine (RBC-PE) at D2, D15 and 37th wk, respectively, contrasting with the important rise of the precursor (18:2 n-6) in all the fractions studied. In RBC-PE, 22:6 n-3 significantly declined from 3.52 +/- 1. 03% at D2 to 2.56 +/- 0.83% at D15 (p < 0.02) and recovered its initial level at 37th wk (4.08 +/- 1.94%). The recovery of long chain polyunsaturated fatty acid homeostasis at that time was also confirmed by the decline of 16:1 n-7 in cholesterol esters (10.69 +/- 3.92 to 4.32 +/- 2.38%).