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Effects of diets rich in monounsaturated fatty acids on plasma lipoproteins--the Jerusalem Nutrition Study. II. Monounsaturated fatty acids vs carbohydrates.

Seventeen male Yeshiva students were randomly allocated to a crossover study with two 12-wk dietary periods of monounsaturated fatty acids (MUFAs) vs a carbohydrate (CHO)-rich diet while concentrations of saturated (SFAs) and polyunsaturated (PUFAs) fatty acids were kept similar. Total plasma cholesterol (TC) decreased significantly by approximately 7.7% and low-density-lipoprotein cholesterol (LDL-C) by 14.4% on the MUFA diet, whereas on the CHO diet no significant change in cholesterol concentrations occurred, in contrast to that predicted by the equations of Keys and Hegsted. Concentrations of high-density-lipoprotein cholesterol (HDL-C) did not change significantly on either diet. On the MUFA diet there was a significantly lower proneness to peroxidation of plasma and LDL lipids and less extensive metabolism of conditioned LDL by peritoneal macrophages. We conclude that dietary MUFAs lower TC and LDL-C concentrations, independently of other dietary fatty acids and in addition may reduce the susceptibility of LDL to oxidative stress.

Adult↗

Conjugated linoleic acid and other beneficial fatty acids in milk fat from cows fed soybean meal, fish meal, or both.

Twelve multiparous Holstein cows at 48 +/- 8 DIM were used in a 4 x 4 Latin square with 21-d periods to determine the effect of replacing soybean meal with fish meal on feed intake, milk yield, and milk composition. Fish meal substituted for soybean meal on an isonitrogenous basis at 0, 25, 50, and 100% of supplemental protein. Total mixed diets were (DM basis) 25% corn silage, 25% alfalfa hay, and 50% concentrate mix. Intake of DM (27.9, 27.8, 26.1, and 25.8 kg/d for diets 1 to 4, respectively) was similar for all diets. Milk yield (37.5, 37.8, 37.2, and 37.7 kg/d) was not affected by diets. Milk protein percentages (3.23, 3.24, 3.31, and 3.35) increased with 100% fish meal supplementation and tended to be higher with 50% fish meal supplementation compared with 100% soybean meal diet. Milk fat percentages (3.18, 2.99, 3.04, and 2.87) and yield were lower with the 100% fish meal than with the 100% soybean meal diet. Concentration of n-3 fatty acids in milk fat (0.54, 0.56, 0.63, and 0.72 g/100 g fatty acids) increased as the proportion of fish meal in the diet increased. Concentrations of c9,t11 conjugated linoleic acid (CLA; 0.39, 0.44, 0.46, and 0.72 g/100 g fatty acids) and transvaccenic acid (TVA; 1.09, 1.19, 1.28, and 1.54 g/100 g of fatty acids) were higher with the 100% fish meal diet than with the 100% soybean meal diet. A total replacement of soybean meal with fish meal in the diet of lactating cows increased milk protein percentages and the beneficial fatty acids (CLA, TVA, and n-3 FA) in milk fat.

Animal Feed↗

Postprandial responses of individual fatty acids in subjects homozygous for the threonine- or alanine-encoding allele in codon 54 of the intestinal fatty acid binding protein 2 gene.

BACKGROUND: The affinity of intestinal fatty acid binding protein (FABP) for fatty acids is regulated by the polymorphism at codon 54 of the FABP2 gene (alanine-to-threonine shift). We found earlier that the threonine-encoding allele (Thr54) is associated with an increased postprandial lipemic response. OBJECTIVE: We studied the postprandial responses of individual fatty acids in subjects homozygous for the Thr54 or alanine-encoding allele (Ala54). DESIGN: Oral-fat-loading tests were performed in 8 subjects homozygous for Thr54 and in 7 subjects homozygous for Ala54. RESULTS: The postprandial responses of most of the 14-18-carbon fatty acids in chylomicron and VLDL triacylglycerols were significantly elevated in the Thr54 homozygotes whereas the relative increases in these fatty acids were not significantly different in both groups. The amounts of 20- and 22-carbon polyunsaturated fatty acids started to increase later than the amounts of shorter ones after the test meal, and the differences between the groups were mostly insignificant. The responses of chylomicron fatty acids correlated positively with postprandial insulin response in the Thr54 homozygotes and inversely in the Ala54 homozygotes. VLDL fatty acid responses correlated with fasting triacylglycerol concentrations in the Ala54 homozygotes but not in the Thr54 homozygotes. CONCLUSION: The threonine-encoding allele of the FABP2 gene is associated with an increased postprandial response of 14-18-carbon fatty acids but not with changes in the relative amounts of individual fatty acids introduced to chylomicron triacylglycerols.

Aged↗

Mass spectrometry of derivatives of cyclopropene fatty acids.

Diketo fatty acids prepared by ozonization of cyclopropene fatty acids have been separated and purified by chromatographic techniques. Mass spectra of esters of these compounds and of methanethiol adducts of cyclopropene acid esters are reported and interpreted. Location of the ring from examination of mass spectra of these derivatives appears to be a straightforward matter.

Chromatography↗

Effects of arachidonic acid and other unsaturated fatty acids on mitogenesis in human lymphocytes.

The effect of fatty acids and other lipids on mitogenic responses in cultured human peripheral blood lymphocytes was studied. Several-fold enhancement of tritiated thymidine incorporation was observed at 0.1 to 5.0 micrograms/ml concentrations of arachidonic acid. Other unsaturated fatty acids produced less marked changes. Increased responsiveness was demonstrable in a variety of media including RPMI 1640 supplemented with 10% fetal calf serum. Changes were also observed in uridine incorporation, total cell number, and blast transformation, indicating that the effect was not on thymidine transport or pool size per se. Arachidonic acid failed to affect PHA binding, indicating that the lectin-cell interaction was not altered. Higher concentrations of fatty acids were inhibitory.

Arachidonic Acids↗

Inhibition of adenylyl cyclase activity in brain membrane fractions by arachidonic acid and related unsaturated fatty acids.

Pretreatment of mouse brain membranes with arachidonic acid (AA) and related unsaturated fatty acids at 30 degrees C for 10 min decreased basal activity and isoproterenol/guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S)- and forskolin-stimulated activities of adenylyl cyclase to a level less than 5% of control. The presence of the carboxyl group on the fatty acids was essential for the inhibition, because no such inhibition was found with ethyl arachidonate or AA attached to diacylglycerols and phospholipids. The AA-mediated inhibition was observed when the activity was measured in the presence of Mn2+ or forskolin and was insensitive to pertussis toxin or guanosine 5'-O-(2-thiodiphosphate) (GDPbetaS), indicating a mechanism independent of GTP-binding proteins. In addition, the fact that stimulators of the adenylyl cyclase catalytic unit, ATP, GTP gamma S and forskolin, when present during pretreatment, attenuate the inhibitory effect of AA may suggest that the catalytic unit is a target of AA. Bovine serum albumin suppressed the inhibition when present in the mixtures for pretreatment, but could not restore the adenylyl cyclase activity that had been reduced by AA, indicating an irreversible inhibition by AA. The effect of AA was found to be additive to P-site-mediated inhibition. The present study suggests the existence of another mechanism of regulation of adenylyl cyclase by unsaturated fatty acids.

Adenosine Triphosphate↗

Lipid metabolism and liver inflammation. II. Fatty liver disease and fatty acid oxidation.

Fatty liver disease (FLD), whether it is alcoholic FLD (AFLD) or nonalcoholic FLD (NAFLD), encompasses a morphological spectrum consisting of hepatic steatosis (fatty liver) and steatohepatitis. FLD has the inherent propensity to progress toward the development of cirrhosis and hepatocellular carcinoma. It is generally difficult to distinguish AFLD from NAFLD on morphological grounds alone despite the distinctions implied by these etiological designations. The indistinguishable spectrum of histological features of both AFLD and NAFLD suggests a possible convergence of pathogenetic mechanisms at some critical juncture that enables the progression of steatohepatitis toward cirrhosis and liver cancer. From a pathogenetic perspective, FLD may be considered a single disease with multiple etiologies. Excess energy consumption and reduced energy combustion appear to be critical events that culminate in lipid storage in the liver. Energy combustion in the liver is controlled by peroxisome proliferator-activated receptor (PPAR)-alpha-regulated mitochondrial and peroxisomal fatty acid beta-oxidation systems and the microsomal omega-oxidation system. PPAR-alpha, a receptor for peroxisome proliferators, functions as a sensor for fatty acids (lipid sensor), and ineffective PPAR-alpha sensing can lead to reduced energy burning resulting in hepatic steatosis and steatohepatitis. Delineation of the pathogenetic aspects of FLD is necessary for developing novel therapeutic strategies for this disease.

Fatty Acids↗

Synthesis of gallic acid based naphthophenone fatty acid amides as cathepsin D inhibitors.

Gallic acid, one of the most abundant plant phenolic acids, has been modified to cathepsin D protease inhibitors. The strategy of modification was proposed basing on some previously reported structure and activity relationship (SAR) studies. The synthesized naphthophenone fatty acid amide derivatives have been evaluated for in vitro cathepsin D inhibition activity. Two of them have shown significant inhibition activity with IC(50) values of 0.06 and 0.14 microM, respectively, as compared against pepstatin (0.0023 microM), the most potent inhibitor known so far. The study revealed that such attempts on gallic acid based pharmacophores might result in potent inhibitors of cathepsin D.

Amides↗

Fatty acid transport in adipocytes monitored by imaging intracellular free fatty acid levels.

Transport of free fatty acids (FFA) across the adipocyte plasma membrane is critical for maintaining homeostasis. To determine the membrane's role in regulating transport we describe here the first measurements of the intracellular (unbound) FFA concentration ([FFA(i)]) and their use in monitoring transport of FFA across 3T3F442A adipocytes. [FFA(i)] was measured by microinjecting cells with ADIFAB, a fluorescently labeled fatty acid-binding protein that is used to measure unbound FFA levels. We used ratio fluorescence microscopy of intracellular ADIFAB to image unbound FFA levels and determined the time course of [FFA(i)] in response to changing the extracellular unbound FFA concentration ([FFA(o)]). [FFA(o)] was clamped at defined levels using complexes of FFA and bovine serum albumin. We show that FFA influx is slow, requiring about 300 s to reach steady state (rate constant approximately 0.02 s(-1)) and saturable (K(o) approximately 200 nm). Efflux is twice as fast as influx, for zero [FFA(o)], but decreases with increasing [FFA(o)]. Surprisingly, at steady state [FFA(i)] is 2-5-fold (average 2-fold) greater than [FFA(o)] and this [FFA(i)]/[FFA(o)] gradient is abolished by depleting cellular ATP. Our results indicate that FFA transport across adipocyte membranes is highly regulated, involving an ATP-driven pump and a mechanism for gating efflux that is sensitive to [FFA(o)]. These characteristics are well described by a membrane carrier model but are not consistent with FFA transport across the membrane's lipid phase. We suggest that these characteristics are important in regulating circulating FFA levels by the adipocyte.

Adipocytes↗

Muscle-specific overexpression of FAT/CD36 enhances fatty acid oxidation by contracting muscle, reduces plasma triglycerides and fatty acids, and increases plasma glucose and insulin.

Increasing evidence has implicated the membrane protein CD36 (FAT) in binding and transport of long chain fatty acids (FA). To determine the physiological role of CD36, we examined effects of its overexpression in muscle, a tissue that depends on FA for its energy needs and is responsible for clearing a major fraction of circulating FA. Mice with CD36 overexpression in muscle were generated using the promoter of the muscle creatine kinase gene (MCK). Transgenic (MCK-CD36) mice had a slightly lower body weight than control litter mates. This reflected a leaner body mass with less overall adipose tissue, as evidenced by magnetic resonance spectroscopy. Soleus muscles from transgenic animals exhibited a greatly enhanced ability to oxidize fatty acids in response to stimulation/contraction. This increased oxidative ability was not associated with significant alterations in histological appearance of muscle fibers. Transgenic mice had lower blood levels of triglycerides and fatty acids and a reduced triglyceride content of very low density lipoproteins. Blood cholesterol levels were slightly lower, but no significant decrease in the cholesterol content of major lipoprotein fractions was measured. Blood glucose was significantly increased, while insulin levels were similar in the fed state and higher in the fasted state. However, glucose tolerance curves, determined at 20 weeks of age, were similar in control and transgenic mice. In summary, the study documented, in vivo, the role of CD36 to facilitate cellular FA uptake. It also illustrated importance of the uptake process in muscle to overall FA metabolism and glucose utilization.

Adipose Tissue↗

Site-specific differences in the fatty acid composition of abdominal adipose tissue in an obese population from a Mediterranean area: relation with dietary fatty acids, plasma lipid profile, serum insulin, and central obesity.

BACKGROUND: Abdominal obesity is associated with coronary risk, although causality is not well established. OBJECTIVE: In an obese Mediterranean population, we measured the fatty acid composition of adipose tissue, its relation with dietary fatty acids and central fat deposition, and its influence on plasma lipids and insulin. DESIGN: Adipose tissue samples were obtained from 84 obese patients (29 men, 55 women) aged 30-70 y (body mass index, in kg/m(2): 27-35). We measured concentrations of insulin and lipids in plasma and fatty acids in subcutaneous, omental, and perivisceral fat. Dietary fatty acid intake was assessed with a 7-d diet record. RESULTS: The population studied was normolipidemic and normoinsulinemic. There were important differences in fatty acid composition between tissue sites: saturated fatty acids were higher and monounsaturated fatty acids were lower in perivisceral than in subcutaneous fat (P < 0.05). Significant correlations were found for oleic, linoleic, alpha-linolenic, and total n-6 polyunsaturated fatty acids between the subject's habitual diet and adipose tissue composition. Oleic and n-3 fatty acids from adipose regions were negatively correlated with apolipoprotein B and triacylglycerols; adipose tissue 22:1n-9, 20:2n-6, stearic acid, and eicosapentaenoic acid were positively correlated with HDL and apolipoprotein A; and adipose tissue myristic acid was negatively correlated with apolipoprotein A (P < 0.05). Central obesity was positively associated with n-6 polyunsaturated fatty acids and inversely associated with monounsaturated fatty acids and n-3 polyunsaturated fatty acids in adipose tissue (P < 0.05). CONCLUSION: The differences found in the composition and metabolism of perivisceral, omental, and subcutaneous fats may indicate that their atherogenic capacities also differ.

Abdomen↗

Regulatory role of E-NTPase/NTPDase in fat/CD36-mediated fatty acid uptake.

Fatty acid translocase (FAT)/CD36-mediated long-chain fatty acid uptake in human umbilical vessel endothelial cells is associated with as yet uncharacterized translocase activity. The molecular mechanism of its function is not yet understood. Numerous attempts to purify rat cardiac sarcolemmal E-NTPase (an integral membrane protein also referred to as ecto-Ca(2+)/Mg(2+)ATPase) have revealed a complete amino acid sequence identity for FAT/CD36 protein. The most striking observation is that purified CD36 from human platelets shows significant E-NTPase activity. In view of recent progress in understanding CD36 functional properties, an attempt is made in this article to illustrate the point that association of E-NTPase (possibly extracellular Ca(2+)/Mg(2+)nucleotide triphosphate diphosphohydrolase) activity with CD36 may be of potential functional significance.

Acid Anhydride Hydrolases↗

Inhibition by arachidonic acid and other fatty acids of dopamine uptake at the human dopamine transporter.

It is known that arachidonic acid, in addition to promoting release of dopamine, can inhibit its transport. The present study provides preliminary information on structure-activity relationships for uptake inhibition by rotating disk voltammetry in human embryonic kidney-293 cells expressing the human dopamine transporter. Except for anandamide, all other fatty acids studied at a pretreatment concentration of 80 microM caused significant reductions in Vmax but not Km. Increasing saturation of the hydrocarbon tails (partial saturation: oleic acid, linoleic acid; full saturation: arachidic acid, stearic acid, stearic acid ethyl ester) removed inhibitory activity incrementally, suggesting a role for cis-unsaturation (folding/bending of hydrocarbon tails). The relative lack of effect of 5,8,11,14-eicosatetraynoic acid also supports the idea that less linear structures are less inhibitory on dopamine uptake. Esterification of the free carboxylic group (arachidonic acid ethyl ester) prevented most of the inhibitory activity, arguing against mere membrane lipid disruption. Finally, the endogenous cannabinoid anandamide greatly reduced uptake Vmax accompanied by a small decrease in Km, a potentially important effect on dopaminergic neurotransmission.

Arachidonic Acid↗

Suppression of fatty acids synthesis in brown adipose tissue of mice fed diets rich in long chain fatty acids.

The influence of dietary lipid on fatty acid synthesis in brown adipose tissue has been investigated by feeding different high-fat diets to cold-acclimated mice for a period of 2 weeks. Fatty acid synthesis was measured in vivo with 3H2O, and the fats used in the study were maize oil, beef tallow and medium chain triacylglycerol oil. In the mice fed the maize oil and the beef tallow diets fatty acids synthesis was inhibited in all tissue examined--interscapular brown adipose tissue, epididymal white adipose tissue, the liver and the carcass. Synthesis was more inhibited, however, in brown adipose tissue than in other tissues, and the inhibition was greater on the maize oil diet than on the beef tallow. The medium chain triacylglycerol oil had no inhibitory effect on fatty acid synthesis in any tissue, and hepatic synthesis was even elevated on this diet. It is concluded that fatty acid synthesis in brown adipose tissue, as in other lipogenic tissues, is subject to strong suppression by dietary long chain fatty acids, and particularly by linoleic acid.

Acclimatization↗

Short communication: Diurnal profiles of conjugated linoleic acids and trans fatty acids in ruminal fluid from cows fed a high concentrate diet supplemented with fish oil, linseed oil, or sunflower oil.

Trans-18:1 and 18:2 isomer composition in ruminal fluid during the daily feeding cycle was examined in 3 cows fed a high concentrate diet (35:65) with 5% (DM basis) sunflower oil (SO), 5% linseed oil (LO), or 2.5% fish oil (FO) in a 3 x 3 Latin square with 3 4-wk periods. Grass hay and concentrate mixtures were fed at 0900, 1300, and 1700 h daily. Ruminal fluid was collected at 0900, 1100, 1300, 1500, 1700, 2000, and 0000 h. Feeding SO resulted in the greatest mean concentrations (% of total fatty acids) of trans10,cis12-18:2 and cis9,trans11-18:2. In particular, trans10,cis12-18:2 with SO was greater at 1500 (0.29%), 2000 (0.34%), and 0000 h (0.25%) relative to 0900 h (0.07%). Cis9,trans11-18:2 concentration increased from 0.47% at 0900 h to a peak of 2.06% at 1100 h; it remained greater than the percentage determined at 0900 h at 1300 (1.4%) through 0000 h (1.1%). Concentration of trans11,cis15-18:2 was greatest with LO, ranging from 3.3% (0900 h) to a peak of 11.4% at 2000 h. Mean trans10-18:1 concentration ranked by diet was SO > FO > LO. Peak trans10-18:1 with SO was observed at 1700 h (14.9%) compared with 0900 h (5.1%). Trans11-18:1 did not differ with diet or time. Stearic acid decreased over time with all diets reaching minimum concentrations at 1700 to 2000 h relative to 0900 h. Feeding FO, however, decreased mean 18:0 concentration 4-fold compared with LO or SO. The moderate effect on concentration of trans-18:1 coupled with accumulation of 18:2 intermediates and the decrease of 18:0 over time suggest that oils reduced the biohydrogenation of 18:2 isomers to trans-18:1.

Animals↗