Generation and esterification of electrophilic fatty acid nitroalkenes in triacylglycerides

Electrophilic fatty acid nitroalkenes (NO₂-FA) are products of nitric oxide and nitrite-mediated unsaturated fatty acid nitration. These electrophilic products induce pleiotropic signaling actions that modulate metabolic and inflammatory responses in cell and animal models. The metabolism of NO₂-FA includes reduction of the vinyl nitro moiety by prostaglandin reductase-1, mitochondrial β-oxidation, and Michael addition with low molecular weight nucleophilic amino acids. Complex lipid reactions of fatty acid nitroalkenes are not well defined. Herein we report the detection and characterization of NO₂-FA-containing triacylglycerides (NO₂-FA-TAG) via mass spectrometry-based methods. In this regard, unsaturated fatty acids of dietary triacylglycerides are targets for nitration reactions during gastric acidification, where NO₂-FA-TAG can be detected in rat plasma after oral administration of nitro-oleic acid (NO₂-OA). Furthermore, the characterization and profiling of these species, including the generation of beta oxidation and dehydrogenation products, could be detected in NO₂-OA-supplemented adipocytes. These data revealed that NO₂-FA-TAG, formed by either the direct nitration of esterified unsaturated fatty acids or the incorporation of nitrated free fatty acids into triacylglycerides, contribute to the systemic distribution of these reactive electrophilic mediators and may serve as a depot for subsequent mobilization by lipases to in turn impact adipocyte homeostasis and tissue signaling events.     

Effects of oleic acid and its congeners,elaidic and stearic acids,on the structural properties of phosphatidylethanolamine membranes

Fatty acid derivatives are abundant in biological membranes, mainly as components of phospholipids and cholesterol esters. Their presence, free or bound to phospholipids, modulates the lipid membrane behavior. The present study shows the differential influence of the C-18 fatty acids (FAs), oleic, elaidic, and stearic acids on the structural properties of phosphatidylethanolamine (PE). X-ray diffraction of PE-FA systems demonstrated that oleic acid (OA) produced important concentration-dependent alterations of the lipid membrane structure: it induced reductions of up to 20-23 degrees C in the lamellar-to-hexagonal transition temperature of 1-palmitoyl-2-oleoyl PE and dielaidoyl PE and regulated the dimensions of the hexagonal lattice. In contrast, elaidic and stearic acids did not markedly alter the phospholipid mesomorphism. The above effects were attributed to the different "molecular shape" of OA (with a kink at the middle of the molecule) with respect to their congeners, elaidic and stearic acids. The effects of free fatty acids (FFAs) on membrane structure are relevant for several reasons: i) some biological membranes contain very high levels of FFAs. ii) Mediterranean diets with high OA intake have been shown to exert protective effects against tumoral and hypertensive pathologies. iii) FFA derivatives have been developed as antitumoral and antihypertensive drugs.     

Long-term effects of cis and trans monounsaturated (18:1) and saturated (16:0) fatty acids on the synthesis and secretion of apolipoprotein A-I- and apolipoprotein B-containing lipoproteins in HepG2 cells

The objective of this study was to compare the long-term effects of oleic (cis 18:1), elaidic (trans 18:1), and palmitic (16:0) acids on hepatic lipoprotein production, using HepG2 cells as an experimental model. The net accumulation in the medium of apolipoprotein A-I (apoA-I) was not significantly altered by fatty acids, whereas that of apoB was increased with oleic and elaidic acids. Oleic acid, and to a lesser extent elaidic and palmitic acids, increased the mass of triglycerides in the medium and the incorporation of [(3)H]glycerol into secreted triglycerides. The incorporation of [(14)C]acetate into cellular and secreted total cholesterol was stimulated by 96% and 83%, respectively, with elaidic acid but was not significantly modified by oleic or palmitic acid. Relative to oleic acid, the secretion of (14)C-labeled phospholipids and triglycerides was decreased 28% to 31% with elaidic and palmitic acids whereas that of free cholesterol and cholesteryl esters was enhanced 93% and 73%, respectively, with elaidic acid but remained unchanged with palmitic acid. Compared with oleic acid, elaidic acid stimulated the secretion of very low density lipoprotein cholesterol (VLDL-Chol), low density lipoprotein cholesterol (LDL-Chol), and high density lipoprotein cholesterol (HDL-Chol) by 43%, 70%, and 34%, respectively, whereas palmitic acid decreased VLDL-Chol but had no significant effect on LDL-Chol and HDL-Chol. The ratios of total cholesterol to HDL-Chol were 3.17, 3.60, and 3.25 with oleic, elaidic, and palmitic acids, respectively; the corresponding ratios of LDL-Chol to HDL-Chol were 0.87, 1.10, and 0.93, respectively. Compared with oleic and palmitic acids, the LDL and HDL particles secreted in the presence of elaidic acid contained higher levels of free cholesterol and cholesteryl esters and a lower content of phospholipids. The phospholipid-to-total cholesterol ratios of HDL were 1.05, 0.40, and 0.76 with oleic, elaidic, and palmitic acids, respectively.Our results indicate that in comparison with cis monounsaturated and saturated fatty acids, trans fatty acids have more adverse effects on the concentration and composition of lipoproteins secreted by HepG2 cells.     

Differential effects of cis and trans fatty acid isomers, oleic and elaidic acids, on the cholesteryl ester transfer protein activity.

In a previous publication (Lagrost, L. and Barter, P.J. (1991) Biochim. Biophys. Acta 1085, 209-216), saturated and cis unsaturated non-esterified fatty acids have been shown to modulate the rate at which cholesteryl esters are transferred from high-density lipoproteins (HDL) to low-density lipoproteins (LDL) in the presence of the human cholesteryl ester transfer protein (CETP). In the present report, the effects of cis (oleic acid) and trans (elaidic acid) monounsaturated isomers on the CETP-mediated transfer of cholesteryl esters between HDL and LDL were compared. Mixtures of human LDL and HDL3, containing or not radiolabelled cholesteryl esters, were incubated at 37 degrees C with CETP in the presence or in the absence of either stearic (18:0), oleic (18:1 cis) or elaidic (18:1 trans) acids. It was observed that oleic acid and elaidic acid had different effects on the CETP-mediated redistribution of radiolabelled cholesteryl esters as well as on the net mass transfer of cholesterol from HDL3 to LDL. In particular, at high non-esterified fatty acid/lipoprotein ratio, the transfer of cholesteryl esters was significantly inhibited by the cis isomer and increased by the trans isomer.     

Modulation of Opioid Receptor Binding by Cis and Trans Fatty Acids

In synaptosomal brain membranes, the addition of oleic acid (cis), elaidic acid (trans), and the cis and trans isomers of vaccenic acid, at a concentration of 0.87 mumol of lipid/mg of protein, strongly reduced the Bmax and, to a lesser degree, the binding affinity of the mu-selective opioid [3H]Tyr-D-Ala-Gly-(Me)Phe-Gly-ol ([3H]DAMGO). At comparable membrane content, the cis isomers of the fatty acids were more potent than their trans counterparts in inhibiting ligand binding and in decreasing membrane microviscosity, both at the membrane surface and in the core. However, trans-vacenic acid affected opioid receptor binding in spite of just marginally altering membrane microviscosity. If the receptors were uncoupled from guanine nucleotide regulatory protein, an altered inhibition profile was obtained: the impairment of KD by the fatty acids was enhanced and that of Bmax reduced. Receptor interaction of the delta-opioid [3H](D-Pen2,D-Pen5)enkephalin was modulated by lipids to a greater extent than that of [3H]DAMGO: saturable binding was abolished by both oleic and elaidic acids. The binding of [3H]naltrexone was less susceptible to inhibition by the fatty acids, particularly in the presence of sodium. In the absence of this cation, however, cis-vaccenic acid abolished the low-affinity binding component of [3H]naltrexone. These findings support the membrane model of opioid receptor sequestration depicting different ionic environments for the mu- and delta-binding sites. The results of this work show distinct modulation of different types and molecular states of opioid receptor by fatty acids through mechanisms involving membrane fluidity and specific interactions with membrane constituents.     

Antioxidants eliminate stereomutation and thioether formation during lipase-catalyzed thioesterification and transthioesterification for the preparation of uniform cis- and trans-unsaturated thioesters

The lipase-catalyzed preparation of acyl thioesters from unsaturated fatty acids and alkanethiols is accompanied by the formation of geometrical isomers via stereomutation and of thioether derivatives via addition at the olefinic bond, both induced by thiyl radicals. Therefore, a method was developed in order to inhibit radical generation by the addition of antioxidants and thus prevent the formation of geometrical isomers and thioether derivatives during the lipase-catalyzed preparation of unsaturated acyl thioesters. In the presence of antioxidants such as 2,6-di-t-butyl-4-methylphenol (BHT) and octyl gallate thioesterification of oleic and elaidic acids with 1-tetradecanethiol as well as transthioesterification of methyl linoleate with 1-tetradecanethiol led to the corresponding geometrically uniform thioesters without radical-induced side reactions. In the absence of antioxidants rapid stereomutation of unsaturated acyl moieties as well as formation of high proportions of thiyl radical-induced addition products such as isomeric 9(10)-S-tetradecyl stearic acids and 9(10)-S-tetradecyl stearic acid tetradecyl thioesters were observed.     

Isomerization of stable isotopically labeled elaidic acid to cis and trans monoenes by ruminal microbes

A previous study showed that oleic acid was converted by mixed ruminal microbes to stearic acid and also converted to a multitude of trans octadecenoic acid isomers. This study traced the metabolism of one of these trans C18:1 isomers upon its incubation with mixed ruminal microbes. Unlabeled and labeled (18-[13C]trans-9 C18:1) elaidic acid were each added to four in vitro batch cultures with three cultures inoculated with mixed ruminal bacteria and one uninoculated culture. Samples were taken at 0, 12, 24, and 48 h and analyzed for 13C enrichment in component fatty acids by gas chromatography-mass spectrometry. At 0 h of incubation, enrichment was detected only in elaidic acid. By 48 h of incubation, 13C enrichment was 18% (P < 0.01) for stearic acid, 7% to 30% (P < 0.01) for all trans C18:1 isomers having double bonds between carbons six through 16, and 5% to 10% for cis-9 and cis-11 monoenes. After 48 h, 13C enrichment in the uninoculated cultures was only detected in the added elaidic acid. This study shows trans fatty acids exposed to active ruminal cultures are converted to stearic acid but also undergo enzymic isomerization yielding a multitude of positional and geometric isomers.     

Plasma lipoprotein lipid and Lp[a] changes with substitution of elaidic acid for oleic acid in the diet.

The effect of additional dietary trans fatty acids (7% energy) on plasma lipids was assessed in a double-blind comparison of four separate diets: 1, enriched with butter fat (lauric-myristic-palmitic); 2, oleic acid-rich; 3, elaidic acid-rich; 4, palmitic acid-rich. The total dietary period was 11 weeks and comprised normal foods plus specific fat supplements. In 27 mildly hypercholesterolemic men, total and LDL cholesterol were significantly lower during the 3-week oleic acid-rich diet, and were similar during the other three diets. For the four diets LDL cholesterol levels were in mg/dl: 1, 163; 2, 151; 3, 165; 4, 161. HDL cholesterol was significantly higher with the palmitic acid-rich diet, 42 mg/dl, compared with elaidic acid, 38 mg/dl, which in turn was not lower than with oleic acid, 38 mg/dl. Plasma elaidic acid concentration rose seven-fold with the trans fatty acid diet but did not increase the vulnerability of LDL to oxidative change. The elaidic acid-rich diet led to significant elevations in the level of Lp[a] compared to all the other test diets. The Lp[a] level increased to 296 +/- 220 U/l in the elaidic acid-rich period from 235 +/- 182 (mean +/- SD) in the first ("butter") period (P less than 0.001) compared with 249 +/- 204 in the palmitic acid period (P less than 0.001) and 236 +/- 201 in the oleic acid period (NS).(ABSTRACT TRUNCATED AT 250 WORDS)     

Saturated Fatty Acid Requirer of Neurospora crassa

Dietary saturated fatty acids containing 12- to 18-carbon atoms satisfy growth requirements of Neurospora crassa mutant cel (previously named ol; Perkins et al., reference 11); unsaturated fatty acids are synthesized by direct desaturation when an appropriate saturate is available. Odd-chain saturates, 15 carbons and 17 carbons long, satisfy the requirement, and elaidic acid (18:1 Delta(9)trans) results in slow growth. Oleic acid and other cis-unsaturated fatty acids do not satisfy growth requirements; however, oleic acid plus elaidic acid result in growth at a faster rate than elaidate alone. The use of a spin-label fatty acid reveals that hyphae produced by cel during a slow basal level of growth have lipids that reflect a relatively rigid state of viscosity compared to wild type. cel Supplemented with fatty acids and wild type supplemented in the same way have lipids of the same viscosities as reflected by electron spin resonance.     

Temperature-dependent specificity of cis-trans isomeric fatty acid interaction with the erythrocyte membrane

Stabilization of red cells against hypotonic haemolysis by cis-trans isomeric free C18 fatty acids occurs with pronounced specificity which is strongly temperature-dependent, but in a distinctly different manner for the two configurational isomers. Oleic acid (cis-18:1) stabilizes very efficiently at 0 degrees C, even at the highest concentrations. Elaidic acid (trans-18:1) causes neither stabilization nor haemolysis at this temperature. At room temperature (23 degrees C), elaidic acid acquires the ability to protect, without turning haemolytic at high concentrations. At 37 degrees C elaidic acid also becomes haemolytic. The protecting effect of oleic acid at 0 degrees C is the result of a rapid reaction. The characteristic, temperature-dependent specificity of cis-trans isomeric C18 fatty acid interaction with the red cell membrane appears to be a general phenomenon, since it was observed alike with erythrocytes of different species.     

Effect of fatty acid supplementation on the lipid composition of Mycobacterium smegmatis ATCC 607, grown at 27° and 37°C

Mycobacterium smegmatis ATCC 607 was grown at 27 and 37°C, with and without exogenous unsaturated fatty acids, viz. elaidic, oleic and palmitoleic acids, added to the growth medium. The total lipid content of M. smegmatis ATCC 607 was lower at 27°C, and with added oleic acid, when compared with the controls, but higher in presence of palmitoleic acid. At 37°C no significant differences were noted in the total lipid content. In general, the total lipid content was lower with all of the fatty acid supplementations at both 27 and 37°C. The phosphatidylethanolamine content was slightly higher at 27°C in the presence of elaidic or palmitoleic acid, but was markedly lower with oleic acid supplementation at 37°C. The cardiolipin content was lower in the presence of any of the fatty acids at 27°C, and higher in the medium supplemented with elaidic or oleic acid at 37°C. The unsaturated to saturated fatty acids ratio was higher with palmitoleic acid supplementation at 27°C, but remained unchanged in cells grown at 37°C. The modifications in mycobacterial lipids are a reflection of the organism's ability to adapt to changing growth conditions.     

Analysis of lipids by gas-liquid chromatography and complementary methods in four strains of Aedes aegypti mosquitoes

Fatty acid composition of total lipids, neutral lipids and phospholipids of strains of Aedes aegypti were determined. The fatty acid composition of the strains differed quantitatively with regard to the relative percentage of commonly occurring fatty acids. Gas-liquid chromatography of fatty acid methyl esters showed 18:1 (oleic or elaidic) to be the predominant fatty acid. The fatty acid was identified as oleic by argentation thin-layer chromatography. A modified colorimetric method was used to determine tissue-free fatty acids. The lipids were predominantly triacylglycerol with lesser amounts of free fatty acids and decreasing amount of sterol ester, sterol, monoacylglycerol, diacylglycerol and hydrocarbons. The data show considerable lipid differences between the Caribbean strains (Les Cayes, Haiti, and San Juan, Puerto Rico) and the Jakarta (Indonesia) strain. The Shimba Hills (Kenya) strain was more similar to Jakarta than to the Caribbean strains. The results obtained with the different strains are discussed in relation to the established oral susceptibility to Dengue 1 and Dengue 2, yellow fever, and genetic analysis by isoenzyme studies.     

Liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry of ω- and (ω-1)-hydroxylated metabolites of elaidic and oleic acids in human and rat liver microsomes

In order to characterize the nature of the active site of cytochrome P450 2E1, the metabolism of various fatty acids with cis/trans geometric configurations has been investigated. A system coupling atmospheric pressure chemical ionization-mass spectrometry detection with HPLC separation was developed as an alternative method for the characterization of hydroxylated metabolites of oleic and elaidic acids in rat and human liver microsomes. Oxidation of oleic and elaidic acids led to the formation of two main metabolites which were identified by LC–MS and GC–MS as ω and (ω-1)-hydroxylated (or 17-OH and 18-OH) fatty acids, on the basis of their pseudo-molecular mass and their fragmentation. The assay was accurate and reproducible, with a detection limit of 25 ng per injection, a linear range from 25 to 1128 ng per injection, no recorded interference, intra-day and inter-day precision with variation coefficients <14%. This LC–MS method was validated with oleic acid by using both radiometric and mass spectrometric detections. A significant correlation was found between the two methods in human (r=0.86 and 0.94 with P<0.05 and 0.01) and rat liver microsomes (r =0.90 and 0.85 with P<0.01 and 0.05) for 17-OH and 18-OH metabolites, respectively. HPLC coupled to mass spectrometry for the analysis of hydroxylated metabolites of elaidic acid offers considerable advantages since the method does not require use of a radioactive molecule, completely separates the two hydroxymetabolites, confirms the identification of each metabolite, and is as sensitive as the radiometric analysis method. This method allowed the comparative study of oleic and elaidic acid hydroxylations by both human and rat liver microsomal preparations.     

Replacement of the aliphatic chains of Clostridium acetobutylicum by exogenous fatty acids: regulation of phospholipid and glycolipid composition.

The membrane lipid aliphatic chains of Clostridium acetobutylicum ATCC 4259 have been extensively modified by growth in biotin-free medium containing vitamin-free casein hydrolysate supplemented with either elaidic acid, oleic acid, or mixtures of palmitic and oleic acids. Growth with elaidic acid resulted in polar lipids containing 88.6% 18:1 acyl chains and 94.5% 18:1 ether-linked chains. Growth with oleic acid resulted in comparable levels of enrichment of the lipids with 18:1 chains and C19 chains containing cyclopropane rings. When cells were grown with mixtures of palmitic and oleic acids, the ether-linked chains of the plasmalogens were greater than or equal to 64% 18:1 plus C19 chains containing cyclopropane rings at all ratios of oleic to palmitic acid in the medium. The acyl chains reflected the palmitic acid content of the medium more closely. Marked changes were observed in both phospholipid and glycosyldiglyceride compositions as the lipid acyl and ether-linked chains became more enriched with unsaturated and cyclopropane chains. The ratio of the glycerol acetal of plasmenylethanolamine to phosphatidylethanolamine increased, the ratio of cardiolipin to phosphatidylglycerol decreased, and the ratio of diglycosyldiglyceride to monoglycosyldiglyceride increased. However, the monoglycosyldiglyceride/diglycosyldiglyceride ratio was lower for cells grown on 100% oleic acid than for cells grown on 60 or 80% oleic acid. In the membranes of cells grown on 100% oleic acid, the ratio of glycolipids to phospholipids was lower than that found in cells grown on 60% oleic acid. These results indicate that C. acetobutylicum regulates its polar lipid composition in a complex manner involving phospholipids and glycosyldiglycerides. These changes can affect the equilibria between those lipids that form bilayers and those lipids that tend to form nonlamellar phases when enriched with unsaturated aliphatic chains. Phosphoglycolipids of unknown structure were also observed in cells grown either with biotin or with fatty acids. The content of the most abundant phosphoglycolipid also varied with the degree of unsaturation of the cellular lipids.     

Unsaturated fatty acid isomers: effects on the circadian rhythm of a fatty-acid-deficient Neurospora crassa mutant

The fatty acids oleic, linoleic, and linolenic, each of which has a cis double bond at the delta 9 position, are known to lengthen the circadian period of conidiation (spore formation) of strains of Neurospora crassa carrying the cel mutation. cel confers a partial fatty acid requirement on the organism and has been used to promote incorporation of exogenous fatty acids. To test whether a physical effect imparted by the cis double bonds, such as increased membrane fluidity, is critical for the perturbation of the rhythm, various isomers of these fatty acids were supplemented to the bd csp cel strain. Positional isomers of oleic acid, such as petroselinic (delta 6) and vaccenic (delta 11) acids, and longer-chain isomers, such as eicosenoic (delta 11) and erucic (delta 13) acids, did not lengthen the rhythm. The shorter-chain palmitoleic (delta 9) acid did not give a consistent lengthening of the rhythm; it may be elongated to vaccenic acid. In contrast, gamma-linolenic acid (delta 6,9,12) dramatically lengthened the period. Linoelaidic acid (the trans,trans isomer of linoleic acid) lengthened the period at 22 degrees C, but elaidic acid (the trans isomer of oleic acid) did not. Elaidic acid was shown to exert a lengthening effect, but only at lower temperatures. The data do not support a direct physical action as the source of the fatty acids' "chronobiotic" ability.     

Cis and trans conformational changes of bacterial fatty acids in comparison with analogs of animal and vegetable origin

The conditions of the formations of trans isomers of fatty acids, depending on the method of processing and storage of the raw material of microbial, plant and animal origin, were investigated. In the composition of lipids, except for the main trans-isomer elaidic acid, nonsignificant amounts of trans -2-hexen-4-ynal, trans-2-formlcyclopro-panecarboxylate, methyl octadeca-9-yn-l1-trans-enoate, trans-2, 2-dimethyl-3-(2-propenyl)-ethyl ester, trans-9-octadecenoic acid, and trans-1,5-heptadiene, and mixed isomers of methyloctadeca-9-yn-11-trans-enoate,-methyl-9-cis, 11-trans-octadecadienoate, l-[trans-4-(2-iodo-ethyl) cyclohexyl]-trans-4-pentylcyclo-hexane and cis-9, and trans 11-octadecenoic acid. The major trans elaidic acid component was detected in natural objects of different origin in quantities not exceeding 0.05–0.11%. The combination of thermal processing with other parameters, especially enzymatic treatment, led to an increased proportion of trans isomers. The content of trans isomers is usually proportional to the time of storage of materials.     

Action of long-chain fatty acids in vitro on Ca2+-stimulatable, Mg2+-dependent ATPase activity in human red cell membranes.

Human red cell membrane Ca2+-stimulatable, Mg2+-dependent adenosine triphosphatase (Ca2+-ATPase) activity and its response to thyroid hormone have been studied following exposure of membranes in vitro to specific long-chain fatty acids. Basal enzyme activity (no added thyroid hormone) was significantly decreased by additions of 10(-9)-10(-4) M-stearic (18:0) and oleic (18:1 cis-9) acids. Methyl oleate and elaidic (18:1 trans-9), palmitic (16:0) and lauric (12:0) acids at 10(-6) and 10(-4) M were not inhibitory, nor were arachidonic (20:4) and linolenic (18:3) acids. Myristic acid (14:0) was inhibitory only at 10(-4) M. Thus, chain length of 18 carbon atoms and anionic charge were the principal determinants of inhibitory activity. Introduction of a cis-9 double bond (oleic acid) did not alter the inhibitory activity of the 18-carbon moiety (stearic acid), but the trans-9 elaidic acid did not cause enzyme inhibition. While the predominant effect of fatty acids on erythrocyte Ca2+-ATPase in situ is inhibition of basal activity, elaidic, linoleic (18:2) and palmitoleic (16:1) acids at 10(-6) and 10(-4) M stimulated the enzyme. Methyl elaidate was not stimulatory. These structure-activity relationships differ from those described for fatty acids and purified red cell Ca2+-ATPase reconstituted in liposomes. Thyroid hormone stimulation of Ca2+-ATPase was significantly decreased by stearic and oleic acids (10(-9)-10(-4) M), but also by elaidic, linoleic, palmitoleic and myristic acids. Arachidonic, palmitic and lauric acids were ineffective, as were the methyl esters of oleic and elaidic acids. Thus, inhibition of the iodothyronine effect on Ca2+-ATPase by fatty acids has similar, but not identical, structure-activity relationships to those for basal enzyme activity. To examine mechanisms for these fatty acid effects, we studied the action of oleic and stearic acids on responsiveness of the enzyme to purified calmodulin, the Ca2+-binding activator protein for Ca2+-ATPase. Oleic and stearic acids (10(-9)-10(-4) M) progressively inhibited, but did not abolish, enzyme stimulation by calmodulin (10(-9) M). Double-reciprocal analysis of the effect of oleic acid on calmodulin stimulation indicated noncompetitive inhibition. Addition of calmodulin to membranes in the presence of equimolar oleic acid restored basal enzyme activity. Oleic acid also reduced 125I-calmodulin binding to membranes, but had no effect on the binding of [125I]T4 by ghosts. The mechanism of the decrease by long chain fatty acids of Ca2+-ATPase activity in situ in human red cell ghosts thus is calmodulin-dependent and involves reduction in membrane binding of calmodulin.     

Oxidation of oleic and elaidic acids in rat and human heart homogenates

Parallel incubations with uniformly 14C-labeled oleic and elaidic acids were conducted to compare oxidation rates in tissue homogenates prepared from rat and human hearts. Radioactivity in 14CO2 and 14C-labeled chain-shortened acid-soluble products was used to measure the extent of oxidation. Oxidation rates (pmol/min per mg heart protein) determined on 14C-labeled acid-soluble products suggest that oleic acid was oxidized 35-40% faster than elaidic acid by both male and female rat heart homogenates, whereas human heart homogenates oxidized these fatty acids at equal rates. Rates for female heart homogenates were somewhat higher than those for males in rats and humans. Rates of formation of 14CO2 were the same for each acid in rat and human heart tissue. Comparative rates of formation of oxidation products expressed as oleic/elaidic ratios from parallel incubations confirm that preferential oxidation of oleic acid occurred with rat heart homogenates, but not with the human heart homogenates. These data suggest that the presence of the trans double bond in elaidic acid does not impair its utilization for energy by human heart muscle.     

Trans fatty acids promote the growth of some Lactobacillus strains

Five Lactobacillus strains (2 L. gasseri, 2 L. plantarum and 1 L. reuteri) were cultured in modified MRS medium containing fatty acids (FAs) instead of Tween 80 for 24 h at 37 degrees C, to learn the effect of saturated and unsaturated FAs on the Lactobacillus growth. Free FAs included palmitic (16:0), palmitoleic (c9-16:1), stearic (18:0), oleic (c9-18:1), elaidic (t9-18:1), cis-vaccenic (c11-18:1), vaccenic (t11-18:1), linoleic (c9, c12-18:2), conjugated linoleic (c9, t11- and t10, c12-18:2), alpha-linolenic (c9, c12, c15-18:3), alpha-eleostearic (c9, t11, t13-18:3), eicosapentaenoic (20:5), and docosahexaenoic (22:6) acids. Among free FAs, oleic acid stimulated the growth of all Lactobacillus strains, whereas palmitoleic acid had almost no affect on the Lactobacillus growth. Saturated FAs such as stearic and palmitic acids inhibited or did not affect the Lactobacillus growth. Polyunsaturated FAs such as alpha-linolenic, eicosapentaenoic and docosahexaenoic acids strongly inhibited the Lactobacillus growth at 7.6 x 10(-4) m. Octadecenoic acids such as oleic, elaidic, cis-vaccenic and vaccenic acids remarkably promoted the growth of L. gasseri, regardless of the different double bond positions and configurations. When oleic or cis-vaccenic acid was incubated with L. gasseri, the FAs was transformed to cyclopropane FAs (methyleneoctadecanoic acids) after incorporation into the cells. On the other hand, trans FAs such as elaidic and vaccenic acids incorporated into the cells were not converted to another FAs. Conjugated linoleic and alpha-eleostearic acids having a trans double bond promoted the Lactobacillus growth. The growth of L. gasseri was also stimulated by trans-rich free FAs from hydrogenated canola and fish oils. These results showed that octadecenoic acid and trans FAs had strong promotion activities for the Lactobacillus growth due to their incorporation into membrane lipids.