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PubMed1975

[Qualitative and quantitative studies on the metabolism of fatty acids, in particular on that of linoleic acid in calves].

24 calves of the breed "Deutsche Schwarzbunte Rasse" were used for qualitative and quantitative investigations on the metabolism of fatty acids, particularly that of linoleic acid. The trial comprised 6 calves in 4 groups. The experimental rations consisted of powdered skim milk, oat meal, milk sugar, coco fat and varying proportions of linoleic acid (1.0%, 1.5%, 2.5%). The control group received the basal ration without supplements of linoleic acid. After a short period of adjustment the metabolic trial was started with 9 periods each lasting 7 days. The composition of fatty acids in the faecal lipids was analysed by gas chromatography. The studies led to the conclusion that the fatty acids contained in the faecal fat were not immediately derived from the dietary fat. The results of the trial also showed that the major proportion of all the fatty acids present in the faecal lipids consisted of only 4 fatty acids, viz. oleic acid, palmitic acid, lauric acid and myristic acid. Changes observed for the content of linoleic acid in faecal lipids were negligible so that the assumption may be made that all of the linoleic acid added was completely digested.

Animal Feed↗
PubMed1975

Enterotoxigenic intestinal bacteria in tropical sprue. IV. Effect of linoleic acid on growth interrelationships of Lactobacillus acidophilus and Klebsiella pneumoniae.

The factors responsible for colonization of the small intestine by enterotoxigenic coliform bacteria in Puerto Ricans with tropical sprue are unknown, but epidemiological observations have suggested that they may be related to an increased dietary intake of long-chain unsaturated fatty acids, particularly linoleic acid, which is known to exert an inhibitory effect on the growth of gram-positive organisms that normally comprise the flora of the small intestine. We have examined, by using a glucose-limited continuous-culture system, what effect this fatty acid exerts on the growth relationships of enteric gram-positive and coliform bacteria. In this system, colonization by an invading strain of Klebsiella pneumoniae was prevented by the presence of an established culture of Lactobacillus acidophilus, principally by virtue of a lowered pH of the medium that was incompatible with Klebsiella growth. However, when the population density of L. acidophilus was reduced by the presence of a sufficient concentration of linoleic acid, the invading K. pneumoniae successfully colonized the system and, once established, suppressed the growth of L. acidophilus. These observations indicate that, under the conditions of our chemostat, gram-positive enteric bacteria suppress coliform growth and that this effect is reversible by the presence of linoleic acid. It remains to be established, however, what pertinence these in vitro observations have to conditions within the intestinal tract of persons living in the tropics.

Enterotoxins↗
PubMed1975

Substitution reactions of linoleic acid hydroperoxide isomerase.

Linoleic acid hydroperoxide isomerase was extracted from corn germ and partially purified by differential centrifugation. This enzyme catalyzed the isomerization of linoleic acid hydroperoxide.(see article) Isomerase also catalyzed the substitution of various reagents at the carbon bearing the hydroperoxide group. These fatty acid products had the following functional groupings: (see article) where X is either oleoyloxy, ethylthio, or methoxy resulting from the presence of oleic acid, ethanethiol, or methanol, respectively. A crude wheat germ extract containing both lipoxygenase and isomerase enzymes reacted with linoleic acid to yield alpha-ketols, gamma-ketols, and a substitution product, the linoleoyloxy ester of alpha-ketol. Characterization of these products from wheat germ enzymes showed that the substitution reaction was not unique to corn germ. Because anions of the reagents tested are typical nucleophiles, the substitution reactions may proceed by a nucleophilic mechanism as mediated by the isomerase enzyme.

Isomerases↗
PubMed1976

Comparative effect of glucagon, dibutyryl cyclic AMP, and epinephrine on the desaturation and elongation of linoleic acid by rat liver microsomes.

The effect of glucagon, dibutyryl cyclic adenosine 3',5'-monophosphate, and epinephrine on the biosynthesis of polyunsaturated fatty acids of the linoleic acid family was studied. The incubations were performed with rat liver microsomes and labeled linoleic acid under desaturating and elongating conditions. Under desaturating conditions linoleic acid was converted to gamma-linolenic acid, whereas under elongating conditions it was converted to 20:2omega6. Glucagon, dibutyryl cyclic AMP, and epinephrine decreased the oxidative desaturation of linoleic acid to gamma-linolenic acid while the elongating reaction was not modified in the experimental conditions tested. Consequently, the results support the hypothesis that the oxidative desaturation of linoleic acid to gamma-linolenic acid is the main controllable step in the biosynthesis of polyunsaturated fatty acids of the linoleic acid family in the microsomes.

Animals↗
PubMed1977

Biohydrogenation and availability of linoleic acid in lactating cows.

Linoleic acid biohydrogenation, absorption and availability for maintenance and milk production in dairy cows fed high grain (60--85% of dry matter) diets were quantitatively estimated by isotope dilution, using two methods of dosing. [1-14C]Linoleic acid-labeled chylomicra and very low density lipoproteins (VLDL) were obtained from lymph of a calf fed [1-14C]linoleic acid and fitted with a thoracic duct-venous shunt. Labeled chylomicra were injected intravenously into two cows: a Jersey (trial 1), and a Holstein (trial 2). Labeled VLDL was injected intravenously into a Holstein cow (trial 3). In trials 4 and 5 the [1-14C]linoleic acid was placed into the omasal canal of two rumen-fistulated Holstein cows. Linoleic acid biohydrogenation (%), absorption (g/day), and availability above requirements for milk production (mg/kg body wt 3/4) were: 68.1 +/- 2.28, 52.1 +/- 2.92, and 244 +/- 19.4 (mean +/- SE), respectively. The biohydrogenation data indicate that both methods of dosing the cows were equally dependable. The estimates of linoleic acid biohydrogenation are consistent with limited data previously reported, indicating that the isotope dilution technique used is a reliable method to estimate linoleic acid absorption in lactating cows. Linoleic acid available to the lactating cow above milk production requirements was more than double the requirement of weanling female rats, when compared on the basis of metabolis body size.

Animal Feed↗
PubMed1978

Tumor promoting phorbol diesters stimulate release of radioactivity from [3H]-arachidonic acid labeled- but not [14C]linoleic acid labeled-cells. Indomethacin inhibits the stimulated release from [3H] arachidonate labeled cells.

The tumor promoting phorbol diester, 12-O-tetradecanoyl-phorbol-13-acetate, stimulates MDCK cells to deacylate cellular phospholipids and to produce prostaglandins when measured as the release of arachidonic acid and its metabolites into the culture fluid. Indomethacin, at levels of 2.8 x 10(-8) to 2.8 x 10(-6) M, inhibits the release of radioactivity from [3H]arachidonate labeled cells stimulated by 12-O-tetradecanoyl-phorbol-13-acetate treatment in a concentration dependent manner. At these concentrations, the conversion of released [3H]arachidonic acid into prostaglandins E2 and F2alpha and the production of PGE2 measured serologically also is suppressed in a concentration dependent manner. Indomethacin, at these levels, has no effect on the acylation of [3H]arachidonic acid into cellular lipids. The tumor promoting phorbol diester does not stimulate the release of radioactive materials from MDCK cells labeled with [14C]linoleic acid, although prostaglandin production by these cells is stimulated.

Animals↗
PubMed1992

Effect of feeding palmitic, oleic, and linoleic acids to Japanese quail hens (Coturnix coturnix japonica). 2. Maternal diets and stage of incubation on the lipid metabolism of quail embryos.

An experiment was conducted to evaluate the effects of diets containing 3% of either palmitic acid (Diet PA), oleic acid (Diet OA), or linoleic acid (Diet LA) and three stages of development (Days 11, 13, and 15 of incubation) on 1) weights of yolk plus yolk sac membrane (TY), yolk sac membrane (YSM), yolk, liver, and extrahepatic tissue (ET); and 2) the fatty acid composition of phospholipid, triglyceride, and cholesterol ester fractions of YSM and ET of quail embryos. Embryos from birds fed Diet LA had the highest (P less than .05) weights of TY and yolk followed by those from birds fed Diet OA and Diet PA. The weight of ET was highest (P less than .05) in embryos from birds fed Diet PA followed by those from birds fed Diet LA and Diet OA. The weights of YSM and liver were not affected by the maternal diet (P greater than .05). The weight of TY decreased whereas the weights of liver and ET increased as incubation progressed (P less than .05). The weight of YSM was maximum at Day 13 of incubation. In the phospholipid, triglyceride, and cholesterol ester fractions of both YSM and ET of embryos, the fatty acid present at the highest level, except palmitic acid, was the one added to the maternal diet. In phospholipids of both YSM and ET the oleic acid content decreased and linoleic acid increased as incubation progressed. In triglycerides and cholesterol esters of both YSM and ET, the levels of palmitic acid increased, but oleic and linoleic acids decreased, with advancing embryonic development. The results of the present study indicate that embryos from birds fed Diet PA mobilize more yolk material and produce heavier ET than embryos from birds fed Diet OA and Diet LA. The fatty acid profiles of phospholipid, triglyceride, and cholesterol esters of embryonic tissues are consistently influenced by dietary fatty acid and the stage of development.

Animals↗
PubMed1979

A dual, concentration-dependent absorption mechanism of linoleic acid by rat jejunum in vitro.

Linoleic acid absorption was studied using everted rat jejunal sacs. At low concentrations (42-1260 microM), the relationship between linoleic acid concentration and its absorption rate fitted best to a rectangular hyperbola. At high concentrations (2.5-4.2 mM) the relationship between the two parameters was linear. The separate additions of 2,4-dinitrophenol, cyanide, or azide, or decrease in the incubation temperature from 37 to 20 degrees C did not change the absorption rate of linoleic acid. Absorption rate of linoleic acid at low concentrations increased as the hydrogen ion and taurocholate concentrations were increased or as the unstirred water layer thickness was decreased. Linoleic acid absorption rate was decreased after the additions of lecithin, oleic, linolenic, and arachidonic acids or the substitution of taurocholate with the nonionic surfactant Pluronic F 68. These observations indicate that a concentration-dependent, dual mechanism of transport is operative in linoleic acid absorption. Facilitated diffusion is the predominant mechanism of absorption at low concentrations, while at high concentrations, simple diffusion is predominant. At low concentrations, the absorption rate of linoleic acid is influenced by the pH, surfactant type and concentration, the simultaneous presence of other polyunsaturated fatty acids, and the thickness of the unstirred water layer.

Animals↗
PubMed1979

Rat testis lipoxygenase-like enzyme. Characterization of products from linoleic acid.

The linoleate oxidation products of the affinity chromatography-purified lipoxygenase-like enzyme isolated from rat testes microsomes were characterized. Three types of reaction products separated by thin-layer chromatography were generally present: polar byproducts (A and B) and hydroperoxides. The methyl hydroxystearates obtained from the enzymically produced hydroperoxides were analysed by gas-liquid chromatography and showed a ratio of 67% 13-hydroxy isomer to 33% 9-hydroxy isomer. The major polar byproduct was analysed by infrared spectra, nuclear magnetic resonance and mass spectrometry (of the toluene-p-sulphonyl derivative) and its structure was established as 13-hydroxy-12-oxo-octadec-cis-9-enoic acid. The possibility of the existence of a linoleate hydroperoxide isomerase in the affinity-purified preparation is discussed.

Animals↗
PubMed1992

A linoleic acid (8R)-dioxygenase and hydroperoxide isomerase of the fungus Gaeumannomyces graminis. Biosynthesis of (8R)-hydroxylinoleic acid and (7S,8S)-dihydroxylinoleic acid from (8R)-hydroperoxylinoleic acid.

The fungus Gaeumannomyces graminis metabolized linoleic acid extensively to (8R)-hydroperoxylinoleic acid, (8R)-hydroxylinoleic acid, and threo-(7S,8S)-dihydroxylinoleic acid. When G. graminis was incubated with linoleic acid under an atmosphere of oxygen-18, the isotope was incorporated into (8R)-hydroxylinoleic acid and 7,8-dihydroxylinoleic acid. The two hydroxyls of the latter contained either two oxygen-18 or two oxygen-16 atoms, whereas a molecular species that contained both oxygen isotopes was formed in negligible amounts. Glutathione peroxidase inhibited the biosynthesis of 7,8-dihydroxylinoleic acid. These findings demonstrated that the diol was formed from (8R)-hydroperoxylinoleic acid by intramolecular hydroxylation at carbon 7, catalyzed by a hydroperoxide isomerase. The (8R)-dioxygenase appeared to metabolize substrates with a saturated carboxylic side chain and a 9Z-double bond. G. graminis also formed omega 2- and omega 3-hydroxy metabolites of the fatty acids. In addition, linoleic acid was converted to small amounts of nearly (65% R) racemic 10-hydroxy-8,12-octadecadienoic acid by incorporation of atmospheric oxygen. An unstable metabolite, 11-hydroxylinoleic acid, could also be isolated as well as (13R,13S)-hydroxy-(9E,9Z), (11E)-octadecadienoic acids and (9R,9S)-hydroxy-(10E), (12E,12Z)-octadecadienoic acids. In summary, G. graminis contains a prominent linoleic acid (8R)-dioxygenase, which differs from the lipoxygenase family of dioxygenases by catalyzing the formation of a hydroperoxide without affecting the double bonds of the substrate.

Ascomycota↗
PubMed1977

Human essential fatty acid deficiency: treatment by topical application of linoleic acid.

An essential fatty acid (EFA) deficiency developed in a 19-year-old man who was being maintained on a long-term regimen of fat-free, intravenous hyperalimentation fluids. The EFA deficiency was reversed after 21 days by daily, topical application of linoleic acid to the patient's skin. The ratio of eicosatrienoic acid (20:3, n-9) to eicosatetraenoic acid (20:4, n-6) decreased to normal levels in the skin and serum with clinical improvement of the EFA deficiency syndrome. The cutaneous manifestations (scalp dermatitis, alopecia, and depigmentation of hair) were reversed with continued, topical application of safflower oil, which contains 60% to 70% linoleic acid.

Administration, Topical↗
PubMed1979

Mechanism of the inhibitory action of linoleic acid on the growth of Staphylococcus aureus.

Linoleic acid, but not stearic acid, inhibited the growth of Staphylococcus aureus NCTC 8325. Growth inhibition was associated with an increase in the permeability of the bacterial membrane. The presence of a plasmid conferring resistance to penicillin (PC plasmid, e.g. pI258blaI-) increased the growth inhibitory and membrane permeability effects of linoleic acid. Under growth inhibitory conditions, linoleic acid was incorporated into the lipid of both PC plasmid-containing and PC plasmid-negative bacteria and there was little difference between these cultures in the uptake or fate of linoleic acid. Experiments using a glycerol auxotroph of S. aureus suggested that free linoleic acid, rather than lipid containing this acid, inhibits growth. Linoleic acid probably inhibits growth by increasing the permeability of the bacterial membrane as a result of its surfactant action, and the presence of the PC plasmid increases these effects.

Bacterial Proteins↗
PubMed1976

In vivo metabolism of labeled oleic and linoleic acids by the laying hen.

Radioactive oleic and linoleic acids, labeled with 3H in the chain and 14C in the carbonyl group, were administered to white leghorn laying hens. Mixtures fed in separate experiments included: (1) 3H- and 14C-labeled oleic acid, (2) 3H- and 14C-labeled linoleic acid and (3) [3H]oleic aicd and [14C] linoleic acid. The 3H/14C ratios of both the neutral lipid and phospholipid fractions from the egg yolk and of the isolated acids from these lipid fractions were compared to that in the administered mixture. Agreement in the 3H/14C ratios for the neutral lipid fraction from each of the feeding experiments indicated that neither the 3H- and 14C labeled acids nor the oleic or linoleic acids were distinguishable during synthesis of the neutral lipid. Analysis of the phospholipid fractions showed that when dual-labeled mixtures of oleic acid were administered, 3H/14C ratios were elevated and, therefore, there was selective elimination of the 14C label. When dual-labeled mixtures of linoleic acid were administered, the 3H/14C ratios were in agreement; and when the two acids were administered simultaneously as a dual-labeled mixture, there was selective incorporation of linoleic acid. These findings indicate separate metabolic pathways for synthesis of neutral lipid and phospholipid in egg yolk as expected, as well as preferential use of the essential fatty acid in the phospholipid by the hen.

Animals↗
PubMed1978

Regulation of hepatic drug metabolism by elaidic and linoleic acids in rats.

Elaidic and linoleic acids were administered at doses of 40 and 200 mg/kg i.p. every second day for 4 weeks to rats fed a fat-free diet. The fatty acids had only a slight effect on the weight gain of the animals. The amount of microsomal protein was slightly decreased with the higher dose of linoleic acid. The higher dose level of both fatty acids decreased the microsomal phospholipid content. The relative amounts of microsomal phospholipid fatty acids were also altered due to fatty acid administration. The activity of microsomal NADPH cytochrome c reductase and microsomal cytochrome P-450 contents were decreased by the higher dose of linoleic acid. The hepatic aryl hydrocarbon hydroxylase and p-nitroanisole O-demethylase activities decreased in fatty acid-treated rats. The UDP-glucuronosyltransferase activity was also lowered after the fatty acid administration. The results suggest that fatty acid-induced changes in the activities of drug-metabolizing enzymes may be due to the microenvironmental changes of membrane-bound enzymes.

Animals↗
PubMed1979

Fetal to maternal transfer of palmitic and linoleic acids across the sheep placenta.

Maternal and fetal blood samples were obtained at 2.5, 10 and 20 min after the injection of 3H-palmitic acid and 14C-linoleic acid into the fetal circulation of pregnant ewes. 3H-palmitic acid was easily detected in the maternal circulation within 2.5 min after its injection into the fetus resulting in an appreciable accumulation in the maternal plasma by the 20th min after injection. In contrast the presence of 14C-linoleic acid in the maternal circulation was barely detectable over the 20-min sampling period. The concentrations of total lipid and unesterified fatty acids within the fetal plasma were considerably lower than in the maternal plasma thereby providing an adverse concentration gradient for the passage of fatty acids between fetus and mother. The differential permeability of the placenta to the passage of the 3H-palmitic acid and 14C-linoleic acid is discussed in relation to their passage from fetus to mother in non-ruminant species and the adverse essential fatty acid status known to exist in the developing ruminant fetus.

Animals↗
PubMed1978

Influence of linoleic acid content of the diet on arterial pressure of salt loaded rats. I. Effects on prostaglandin metabolism and sympathetic nervous system.

1. Compared with linoleic acid rich and pellet diet linoleic acid free diet causes an increase in blood pressure in salt loaded rats. The blood pressure increasing effect of linoleic acid poor diet could not be augmented by linoleic acid free diet. 2. The blood pressure was increased by indomethacin in linoleic acid rich and pellet fed rats. In linoleic acid free fed animals indomethacin shows only a brief augmentation of blood pressure. 3. Prostaglandin (PG) biosynthesis was decreased in isolated kidneys and aorta but increased in the kidney medulla homogenate after a four-week linoleic acid free diet. 4.. Chemical sympathectomy by intracerebroventricular injections of 6-hydroxydopamine abolished the blood pressure increasing effect of linoleic acid free diet. We postulate that changes in the PG metabolism and in the activity of sympathetic nervous system are causes for the elevated blood pressure of linoleic acid free fed salt loaded rats and we conclude that the function of the cardiovascular system is influenced favourably by a linoleic acid rich diet.

Animals↗
PubMed1992

Volatile compound content and fatty acid composition of pork as influenced by linoleic acid content of the diet.

Eighty pigs (average weight of 60 kg) were allotted by weight and sex to pens and treatments. There were four dietary treatments, five pens per treatment, and four pigs per pen. Diets consisted of a typical corn-soybean mix containing 9% total fat, 3% from the corn-soybean mix and 6% added. The four dietary treatments included 1) 6% safflower oil, 2) 4% safflower oil and 2% tallow, 3) 2% safflower oil and 4% tallow, and 4) 6% tallow, resulting in 6.1, 4.6, 3.2, and 1.76% linoleic acid, respectively, in the diet. Pigs were slaughtered at an average weight of 100 kg. Proximate composition, tristimulus color coordinates (L, a, and b values), pH, and flavor difference of the longissimus muscle (LM) were evaluated. Fatty acid content (milligrams per 100 grams of tissue) of the subcutaneous fat and LM and headspace volatile content of the LM were determined by capillary gas liquid chromatography. Proximate composition, color, pH, and flavor of the LM were not influenced by diet. Fatty acid content of the subcutaneous fat and LM and volatile content of the LM were influenced by diet. Increased levels of safflower oil in the diet resulted in less C16:0 and C18:1 and more C18:2, C20:2, and C20:3 in the subcutaneous fat. The LM contained more C18:2 and less C18:3 and C24:0 due to increased levels of safflower oil in the diet. Compared with the 6% tallow diet, LM from pigs fed the 4 or 6% safflower diets contained more pentanal, hexanal, 2-heptanone, trans-2-heptenal, 2-pentyl furan, 2-ethyl-1-hexanol, decanal, and undecanal.(ABSTRACT TRUNCATED AT 250 WORDS)

Adipose Tissue↗