Specific binding of [3H]ouabain to heart is inhibited by long-chain fatty acids and alcohols

Long-chain fatty acids and alcohols inhibit specific binding of [³H]ouabain to a particulate fraction from dog heart. The magnitude of inhibition increases with chain length, reaching a maximum with lauric acid, myristoleic acid and decanol in a series of saturated fatty acids, unsaturated fatty acids, and alcohols, respectively, followed by a decline with longer chain members of homologous series. Unsaturated fatty acids and alcohols are more inhibitory than their corresponding saturated congeners; in general, inhibitory potency is greater in cis than trans forms and increases with higher degree of unsaturation. Methyl esters of both saturated and unsaturated fatty acids tested were inactive at 10^?3m or lower concentrations. The inhibition of ouabain binding by fatty acids and alcohols was specific and appears to be competitive. This study extends our earlier findings on the inhibitory activity of fatty acid fractions from bovine liver.     

Dietary alpha-cyclodextrin lowers low-density lipoprotein cholesterol and alters plasma fatty acid profile in low-density lipoprotein receptor knockout mice on a high-fat diet

High dietary intake of saturated fat and cholesterol, and elevated low-density lipoprotein cholesterol levels are some of the modifiable risk factors for cardiovascular disease. α-Cyclodextrin (a-CD) when given orally has been shown in rats to increase fecal saturated fat excretion and to reduce blood total cholesterol levels in obese hypertriglyceridemic subjects with type 2 diabetes mellitus. In this study, the effects of dietary a-CD on lipid metabolism in low-density lipoprotein receptor knockout mice were investigated. Low-density lipoprotein receptor knockout mice were fed a “Western diet” (21% milk fat) with or without 2.1% of a-CD (10% of dietary fat content) for 14 weeks. At sacrifice, there was no difference in body weight; but significant decreases were observed in plasma cholesterol (15.3%), free cholesterol (20%), cholesterol esters (14%), and phospholipid (17.5%) levels in mice treated with α-CD compared with control mice. The decrease in total cholesterol was primarily in the proatherogenic apolipoprotein B–containing lipoprotein fractions, with no significant change in the high-density lipoprotein fraction. Furthermore, α-CD improved the blood fatty acid profile, reducing the saturated fatty acids (4.5%) and trans-isomers (11%) while increasing (2.5%) unsaturated fatty acids. In summary, the addition of α-CD improved the lipid profile by lowering proatherogenic lipoproteins and trans-fatty acids and by decreasing the ratio of saturated and trans-fatty acids to polyunsaturated fatty acids (−5.8%), thus suggesting that it may be useful as a dietary supplement for reducing cardiovascular disease.     

The influence of dietary unsaturated cis and trans and saturated fatty acids on tissue lipids of swine

A feeding trial was conducted to evaluate the effects of dietary trans unsaturated fatty acids (trans fat) and of the interplay of dietary saturated fatty acids (saturated fat), cis unsaturated fatty acids, (cis fat) and trans fat on tissue lipids, particularly those effects suggestive of angiotoxicity. Swine were fed for 10 months a diet containing 17% added fat. Seven blends of varying proportions of the 3 fat components provided sufficient sample points to permit an examination of the interplay. Parameters under study included weight gain, serum cholesterol and triglyceride concentrations, lipoprotein lipid profile, total lipid and cholesterol concentrations of liver, heart and aorta, fatty acid composition of liver and aorta lipids and hepatic fatty acid synthesis and cholesterol synthesis and oxidation. Fat blends containing disproportionately high levels of saturated or cis fat generally elicited responses consistent with results reported by others. The notable exception was the serum cholesterol concentration. Throughout the study, the swine were hypercholesterolemic. Swine fed the high saturated fat blend had serum cholesterol levels equal to those swine fed the high cis fat blend. Serum cholesterol levels in the swine fed the other fat blends were more elevated. Another apparent anomaly was the lower concentration of lipid in the aortas of swine fed the high-saturated fat diet. The impact of the trans fat was modulated by the relative proportions of saturated and cis fat in the diet. The impact of trans fat was of greater magnitude for most parameters when the fat blend was low in saturated fat. The sole parameter suggestive of trans fat-mediated angiotoxicity was the distribution of lipids in lipoprotein fractions. Swine fed diets containing trans fat had lower relative proportions of the alpha-lipoprotein lipids. Although hypercholesterolemic, the high fat diets were not overtly angiotoxic except when fed to swine that carried a specific immunogenetically-defined low density lipoprotein.     

Dietary trans fatty acid

Trans fatty acids are unsaturated fatty acids that contain at least one double bond in the trans configuration. In the diet they occur at relatively low levels in meat and dairy products as a by-product of fermentation in ruminant animals or in hydrogenated fats as a consequence of the hydrogenation process. In general, dietary hydrogenated fat/trans fatty acids have been reported to increase LDL cholesterol levels relative to oil in the natural state or cis fatty acids. In contrast, dietary hydrogenated fat/trans fatty acids have been reported have to have little effect or decrease HDL cholesterol levels, the later observation restricted to relatively high intakes of trans fatty acids. These two effects result in higher, therefore less favorable, total or LDL cholesterol/HDL cholesterol ratios. Significant increases in Lp(a) levels have been reported after consumption of diets relatively high in trans fatty acids compared with either unsaturated or saturated fatty acids. However, the magnitude of the change is for the most part small and the physiological significance of this observation has yet to be resolved. Data related to the mechanism by which hydrogenated fat/trans fatty acids alter serum lipid levels and other risk factors for cardiovascular disease are in the nascent stages. At this time it would appear prudent that public health recommendations should be aimed at encouraging the moderate consumption of products low in saturated fat or minimally hydrogenated. Trans fatty acids intake should not be stressed at the expense of saturated fat but should augment it.     

Distinctive roles of unsaturated and saturated fatty acids in hyperlipidemic pancreatitis

AIM: To investigate how the saturated and unsaturated fatty acid composition influences the susceptibility of developing acute pancreatitis.METHODS: Primary pancreatic acinar cells were treated with low and high concentrations of different saturated and unsaturated fatty acids, and changes in the cytosolic Ca²⁺ signal and the expression of protein kinase C (PKC) were measured after treatment.RESULTS: Unsaturated fatty acids at high concentrations, including oleic acid, linoleic acid, palmitoleic acid, docosahexaenoic acid, and arachidonic acid, induced a persistent rise in cytosolic Ca²⁺ concentrations in acinar cells. Unsaturated fatty acids at low concentrations and saturated fatty acids, including palmitic acid, stearic acid, and triglycerides, at low and high concentrations were unable to induce a rise in Ca²⁺ concentrations in acinar cells. Unsaturated fatty acids at high concentrations but not saturated fatty acids induced intra-acinar cell trypsin activation and cell damage and increased PKC expression.CONCLUSION: At sufficiently high concentrations, unsaturated fatty acids were able to induce acinar cells injury and promote the development of pancreatitis. Unsaturated fatty acids may play a distinctive role in the pathogenesis of pancreatitis through the activation of PKC family members.     

Mediterranean-like mix of fatty acids induces cellular protection on lipid-overloaded hepatocytes from western diet fed mice

Introduction and objective. Non-alcoholic fatty liver disease remains as one of the main liver disorders worldwide. It is widely accepted that is the kind of lipid, rather than the amount deposited in the cells that determines cell damage. Cholesterol and saturated free fatty acids are deleterious lipids when accumulated but, in contrast, there are some valuable lipids that could counteract those with harmful properties. Much of this knowledge arises from studies using a single fatty acid, but the effects of a combination of fatty acids, as obtained by diet has been poorly addressed. In the present work, we were focused to figure out the cellular effect of two different mixes of fatty acids, one with high proportion of saturated fatty acids, and another one with high proportion of unsaturated fatty acids (Mediterranean-like) in a cellular model of steatosis. Material and methods. Primary mouse hepatocytes from animals fed with a western diet (high fat and carbohydrates diet), were treated with both mixes of fatty acids for 24 h. Results. Our data clearly show that only the high unsaturated fatty acid mix induced a decrease in triglycerides (47.5%) and cholesterol (59%) content in steatotic hepatocytes mediating cellular protection associated to the decrement of ROS and oxidative damage. The mixture of high saturated fatty acids exhibited no effects, preserving high levels of cholesterol and triglycerides and oxidative damage. In conclusion, our results show that Mediterranean-like mix of fatty acids exerts cellular protection in steatosis by decreasing triglycerides, cholesterol, ROS content and oxidative damage.     

Ern?hrung bei diabetischer Dyslipid?mie

Dyslipidemia in diabetes is characterized by low high-density lipoprotein (HDL) cholesterol, high triglyceride levels and higher concentrations of atherogenic lipoprotein molecules. Various interventions are of importance in the nutritional therapy of dyslipidemia. An increased intake of unsaturated fatty acids from vegetable oils at the expense of saturated fatty acids lowers low-density lipoprotein (LDL) cholesterol. Trans-fatty acids (food sources: fat spreads and foods with partially hydrogenated fat, fried foods, fat-rich baked goods and sweets) cause an even more detrimental lipoprotein profile compared to saturated fatty acids and their intake should be limited. Significant reductions of LDL cholesterol are also achievable by fiber-rich foods and foods enriched with plant sterols and stanols. A reduction of body weight, an increase in physical activity and a limitation of alcohol consumption to moderate amounts are effective interventions to control triglyceride and HDL cholesterol levels. Triglycerides can also be reduced by supplementation with long-chain ??3 fatty acids (fish oil). Higher proportions of dietary carbohydrates cause higher triglyceride levels, therefore, moderation of carbohydrates in favor of unsaturated fatty acids can be an effective dietary strategy and the major focus is to limit the consumption of foods and beverages with added saccharose or fructose.     

Determination of lipid A and endotoxin in serum by mass spectroscopy

A quantitative technique for determining lipid A content of endotoxin added to serum by combined gas chromatography-mass spectrometry is described. This technique uses detection of the β-hydroxymyristic acid content of Salmonella minnesota R595 lipopolysaccharide by selected ion monitoring at atomic mass unit of 315.4 The fatty acids produced on hydrolysis of serum containing lipopolysaccharide were extracted and the methyl esters were made. Silica gel chromatography was used to separate methyl esters of hydroxy fatty acids from other fatty acid methyl esters. Trimethylsilyl ether derivatives of the hydroxy fatty acid methyl ester fraction were quantitated by this technique. As little as 200 fmol of β-hydroxymyristic acid could be detected.     

Metabolic fate of fatty acids in type II cells isolated from adult rat lung

The present study is concerned with the metabolic fate of palmitate, oleate and linoleate in isolated rat lung type II cells. The cells readily oxidize the exogenously supplied fatty acids to CO₂ and incorporate them into lipids. The distribution between the pathways of oxidation and esterification is similar for saturated and unsaturated fatty acids. The majority of the fatty acids taken up by the cells is utilized for lipid synthesis. The fatty acids are incorporated preferentially into phospholipids, particularly into phosphatidylcholine. Addition of unsaturated fatty acids decreases the utilization of palmitate by type II cells. The distribution of palmitate between oxidation and esterification is not altered in the presence of unsaturated fatty acids. Addition of carnitine stimulates the fatty acid oxidation and decreases the esterification of fatty acids.     

Long-chain fatty acids activate calcium channels in ventricular myocytes.

Nonesterified fatty acids accumulate at sites of tissue injury and necrosis. In cardiac tissue the concentrations of oleic acid, arachidonic acid, leukotrienes, and other fatty acids increase greatly during ischemia due to receptor or nonreceptor-mediated activation of phospholipases and/or diminished reacylation. In ischemic myocardium, the time course of increase in fatty acids and tissue calcium closely parallels irreversible cardiac damage. We postulated that fatty acids released from membrane phospholipids may be involved in the increase of intracellular calcium. We report here that low concentrations (3-30 microM) of each long-chain unsaturated (oleic, linoleic, linolenic, and arachidonic) and saturated (palmitic, stearic, and arachidic) fatty acid tested induced multifold increases in voltage-dependent calcium currents (ICa) in cardiac myocytes. In contrast, neither short-chain fatty acids (less than 12 carbons) or fatty acid esters (oleic and palmitic methyl esters) had any effect on ICa, indicating that activation of calcium channels depended on chain length and required a free carboxyl group. Inhibition of protein kinases C and A, G proteins, eicosanoid production, or nonenzymatic oxidation did not block the fatty acid-induced increase in ICa. Thus, long-chain fatty acids appear to directly activate ICa, possibly by acting at some lipid sites near the channels or directly on the channel protein itself. We suggest that the combined effects of fatty acids released during ischemia on ICa may contribute to ischemia-induced pathogenic events on the heart that involve calcium, such as arrhythmias, conduction disturbances, and myocardial damage due to cytotoxic calcium overload.     

Stimulating effect of blood serums from tumor-bearing rats on cholesteryl ester synthesis in normal rat liver cytosol in vitro

Addition of diluted blood serum from tumor-bearing rats stimulated significantly the synthesis of cholesteryl esters from labeled cholesterol and endogenous fatty acids in the cytosol derived from normal rat liver. With both Zajdela and Walker transplantable tumors this effect was found to be associated with the most intensive period of tumor growth. During chemical carcinogenesis induced by a single subcutaneous administration of benzo(a)pyrene the stimulating effect of sera was found to precede several weeks the appearance of palpable tumors and persisted during the period of progressive tumor growth. With all tumors used, sera in ultimate stages of tumor growth failed to show a stimulating effect. The stimulating effect was due to the presence of a yet unidentified lipid. Higher quantities of this substance may appear in the serum of tumor-bearing animals to meet higher requirements for cholesteryl esters during tumor growth. The stimulating effect of the blood serum on cholesteryl esters may be a useful marker of malignant tumors in humans.     

Modifications of proteins by polyunsaturated fatty acid peroxidation products

The ability of unsaturated fatty acid methyl esters to modify amino acid residues in bovine serum albumin (BSA), glutamine synthetase, and insulin in the presence of a metal-catalyzed oxidation system [ascorbate/Fe(III)/O(2)] depends on the degree of unsaturation of the fatty acid. The fatty acid-dependent generation of carbonyl groups and loss of lysine residues increased in the order methyl linoleate < methyl linolenate < methyl arachidonate. The amounts of alkyl hydroperoxides, malondialdehyde, and a number of other aldehydes that accumulated when polyunsaturated fatty acids were oxidized in the presence of BSA were significantly lower than that observed in the absence of BSA. Direct treatment of proteins with various lipid hydroperoxides led to a slight increase in the formation of protein carbonyl derivatives, whereas treatment with the hydroperoxides together with Fe(II) led to a substantial increase in the formation of protein carbonyls. These results are consistent with the proposition that metal-catalyzed oxidation of polyunsaturated fatty acids can contribute to the generation of protein carbonyls by direct interaction of lipid oxidation products (alpha,beta-unsaturated aldehydes) with lysine residues (Michael addition reactions) and also by interactions with alkoxyl radicals obtained by Fe(II) cleavage of lipid hydroperoxides that are formed. In addition, saturated aldehydes derived from the polyunsaturated fatty acids likely react with lysine residues to form Schiff base adducts.     

Dietary fats, fatty acids, and their effects on lipoproteins

All saturated fatty acids, with the notable exception of stearic acid (C18:0), raise low-density lipoprotein (LDL) cholesterol levels. A few less ubiquitous fatty acids also have LDL cholesterol effects. Trans-monounsaturated fatty acids, at equivalent doses of saturated fatty acids, raise LDL cholesterol. Polyunsaturated fatty acids, at three times the dose of saturated fatty acids, lower LDL cholesterol. Higher intakes of most fatty acids raise high-density lipoprotein (HDL) cholesterol, with the notable exception of trans-monounsaturated fatty acids, which lower HDL cholesterol to the same extent as carbohydrate when either is substituted for other dietary fatty acids. Conjugated linoleic acids containing both cis and trans bonds and cis-monounsaturated fatty acids neither raise nor lower cholesterol concentrations of lipoproteins. The omega-3 fatty acids from fish lower triglyceride levels. Although dietary composition remains an important, modifiable predictor of dyslipidemia, overconsumption of any form of dietary energy may replace overconsumption of saturated fat as the primary factor that increases lipid and lipoprotein levels.     

A comparison of the surfactant associated lipids derived from reptilian and mammalian lungs

The lungs of the central netted dragon Ctenophorus nuchalis are bag-like, with most of the gas exchange region located in the anterior third. Although the faveoli are much larger than the mammalian alveoli, the lizard at 37 degrees C has approximately 70 times more surfactant phospholipid per unit area of respiratory surface than does a similar sized mammal. However, when expressed as per wet lung weight, lizards and rats possessed similar amounts of phospholipids. Dipalmitoylphosphatidylcholine was the principal phospholipid in both species. However, major differences existed in the phospholipid, neutral lipid and fatty acid profiles. Whereas the lizard contained neither phosphatidylglycerol nor phosphatidylethanolamine it had more cholesterol, esterified cholesterol, acylglycerides and unsaturated fatty acids. Although the ratio of saturated:unsaturated fatty acids was similar in rats and lizards, palmitic acid predominated in the former. The composition of lizard surfactant suggests that it would adsorb rapidly at reduced body temperature.     

Fatty acid and lipid composition of the monkey retina in diet-induced hypercholesterolemia

We determined the fatty acid composition of the lipids of cynomolgus monkey retina in animals fed commercial chow or a saturated fat, cholesterol-enriched atherogenic diet for 100 days. Dososahesaenoic acid (22 :6) accounted for 25.8% of the ethanolamine phosphoglyceride fatty acids, 17.6% of the serine plus inositol phosphoglyceride fatty acids, 8.4% of the choline phosphoglyceride fatty acids and 5.8% of the neutral lipid fatty acids in the retinas of the chow-fed animals. Therefore, monkey retinas, like those of other mammalian species, ordinarily contain large amounts of 22 : 6. Retinas from the monkeys fed the atherogenic diet contained less 22 : 6 as well as other polyunsaturates in each of the phospholipid classes. The decrease in polyunsaturates was compensated for by increases in palmitic, stearic, and oleic acids. There was no difference in the amount of phospholipid, the distribution of phospholipid classes, or the amount of cholesterol in the retinas of the monkeys fed the atherogenic diet. These results indicate that the single type of lipid alteration produced in the retina by a diet enriched in saturated fat and cholesterol is a decrease in the polyunsaturation of the retinal phospholipids. The reduction in retinal 22 : 6 content might have significance for photoreceptor function.     

In Vitro Synthesis of Triglycerides and Cholesterol in Human Gallbladder Mucosa

Triglyceride and sterol synthesis was investigated in vitro in the gallbladder mucosa from control subjects and patients with acalculous cholesterolosis. The incorporation rate of ¹⁴C-acetate was 1.6 ± 0.2 nmol/g/h into cholesterol (sum of squalene, methyl sterols, and cholesterol) and 5.7 ± 0.8 nmol/g/h into triglycerides. The rates were significantly correlated with each other (r = 0.667). The conversion of ³H-mevalonate into cholesterol (49 ± 10 nmol/g/h) and triglycerides (4.7 ± 1.2 nmol/g/h) indicated a high activity in the postmevalonate cholesterol synthesis and an active shunt pathway of mevalonate metabolism. The synthesis rates of cholesterol, triglycerides, and sterol esters were closely interrelated, were unaltered in cholesterolosis, and were not correlated with the serum, biliary, and mucosal lipid concentrations. Thus, despite marked lipid accumulation the lipid synthesis proceeds effectively in the gallbladder mucosa with cholesterolosis.     

Sterol-dependence of gastric protective activity of unsaturated phospholipids

The major aim of this study was to investigate the gastric protective effect of unsaturated phospholipids and to determine the ability of neutral lipids to enhance this activity. We found that although a liposomal suspension of unsaturated phosphatidylcholine (PC) administered intragastrically failed to protect rats from acid-induced gastric ulcer formation, addition of cholesterol to unsaturated PC induced a dose-dependent protective response with the maximally effective dose, reducing lesion score greater than 70%. This effect also was seen with the plant sterol, beta-sitosterol (reducing lesion score by 81.6 +/- 36%) but was blocked if cholesterol was esterified to fatty acids of varying chain length. Addition of sterols to liposomes of saturated dipalmitoylphosphatidylcholine, in contrast, attenuated the gastric protective action of the saturated PC. It appears that the protective mechanism elicited by sterols and unsaturated PC is not mediated by alterations in gastric emptying rate or prostaglandin biosynthesis, although maintenance of surface hydrophobicity may be involved. These results suggest that the sterol may promote the packing of adjacent unsaturated phospholipid molecules of either the cell membrane or a putative extracellular hydrophobic lining of the gastric epithelium to provide the mucosa with protection against luminal acid.     

Lipid and protein segregation in Escherichia coli membrane: morphological and structural study of different cytoplasmic membrane fractions.

Lipid and protein segregations can be induced in E. coli cytoplasmic membranes by conformational transitions of their lipid hydrocarbon chains from a disordered to an ordered state. For E. coli strain K 1059 (an unsaturated fatty acid auxotroph) supplemented with linolenic acid, the segregation leads to large areas of membrane surfaces having distinctly different morphological characteristics (smooth compared with strongly particulated fracture faces, as visualized by freeze fracture electron microscopy). The different regions are physically separated by osmotic lysis of spheroplasts at temperatures below those of the order-disorder transition of the lipid hydrocarbon chains. The analysis of the different cytoplasmic membrane fractions provides a direct demonstration and allows a direct analysis of the segregation. As compared to the nonfractionated membranes, the membrane regions corresponding to the smooth fracture surfaces are poor in proteins, rich in lipids, and enriched in saturated fatty acids, while the membrane regions corresponding to the strongly particulated fracture surfaces are rich in proteins, poor in lipids, and enriched in unsaturated fatty acids. Quantitative information about the extent of these segregations is obtained from high-angle x-ray diffraction of the different membrane fractions and of the corresponding total lipid extracts.     

The comparative reductions of the plasma lipids and lipoproteins by dietary polyunsaturated fats: Salmon oil versus vegetable oils

The lower plasma lipid levels and lower incidence of atherosclerotic diseases in Greenland Eskimos suggested that the unusual fatty acids present in their diet of seal and fish may be anti-atherogenic. These fatty acids are eicosapentaenoic (C20:5) and docosahexaenoic (C22:6) acids and are of the omega-3 fatty acid family. We have compared a salmon oil diet containing high levels of these unique fatty acids to a control diet high in saturated fat and to a vegetable oil diet high in linoleic acid (C18:2). All diets contained 40% of the total calories as fat and 500 mg of cholesterol; they differed only in fatty acid composition. In 4 wk the salmon oil diet reduced plasma cholesterol levels from 188 to 162 mg/dl (p < 0.001) and triglyceride levels from 77 to 48 mg/dl (p < 0.005). LDL and VLDL cholesterol levels changed from 128 to 108 and 13 to 8 mg/dl (p < 0.005), respectively. HDL cholesterol levels did not change. The vegetable oil diet caused similar decreases in cholesterol levels but did not lower triglyceride levels. The omega-3 fatty acids comprised up to 30% of the total fatty acids in each plasma lipid class after the salmon diet. Fish oils contain fatty acids which may be metabolically unique and potentially useful in the control of both hypercholesterolemia and hypertriglyceridemia.