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PubMed1993

Photoreactive fatty acid analogues that bind to the rat liver fatty-acid binding protein: 11-(5'-azido-salicylamido)-undecanoic acid derivatives.

Photoreactive probes for the hydrophobic pocket of the liver fatty acid-binding protein, 11-(5'-azido-salicylamido)-undecanoic acid (5' ASU) and its acetyl ester (Ac5' ASU), were synthesized and their interaction with the protein was assessed. Fatty acid-binding proteins are closely related proteins which are abundantly expressed in tissues with active lipid metabolism. A simple model that assumes that the protein possesses a single kind of sites fitted the binding of radioiodinated 5' ASU to L-FABP satisfactorily. The apparent dissociation constant, 1.34 x 10(-7) M, evidenced a slightly higher affinity than that reported for C16-C20 fatty acids. Consistent with the binding curve, 5' ASU effectively competed with palmitic acid for the hydrophobic sites and the effect was nearly complete for concentrations of 1 microM; oleic acid, in turn, displaced the radiolabelled probe. Irradiation at 366 nm of 125I-5' ASU bound to L-FABP caused the covalent cross-linking of the reagent. The amount of radioactivity covalently bound reached a maximum after 2 min thus agreeing with the photo-activation kinetics of the unlabelled compound that evidenced a t1/2 of 31.1 sec. The yield with which probes bound to L-FABP became covalently linked to the protein, appraised after SDS-PAGE of irradiated samples, was estimated as 23 and 26 per cent for 5' ASU and Ac5' ASU respectively. In turn, irradiation of L-FABP incubated with 5' ASU or Ac5' ASU resulted in the irreversible loss of about one fourth its ability to bind palmitic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed2005

Influence of dietary conjugated linoleic acid (CLA) on lipid and fatty acid composition in liver and flesh of Atlantic salmon (Salmo salar).

The aim of the present study was to determine the effects of conjugated linoleic acid (CLA) on lipid and fatty acid metabolism in Atlantic salmon. The overall objective being to test the hypotheses that CLA has beneficial effects in salmon including growth enhancement, improved flesh quality through decreased adiposity and lipid deposition thereby minimising detrimental effects of feeding high fat diets, and increased nutritional quality through increased levels of beneficial fatty acids including n-3 highly unsaturated fatty acids (HUFA) and CLA itself. Salmon smolts were fed diets containing two levels of fish oil (low, approximately 18% and high, approximately 34%) containing three levels of CLA (a 1:1 mixture of 9-cis,trans-11 and trans-10,cis-12. at 0, 1 and 2% of diet) for 3 months and the effects on growth performance, liver and muscle (flesh) lipid contents and class compositions, and fatty acid compositions determined. The diets were also specifically formulated to investigate whether the effects of CLA, if any, were more dependent upon absolute content of CLA in the diet (as percentage of total diet) or the relative level of CLA to other fatty acids. Dietary CLA in salmon smolts had no effect on growth parameters or biometric parameters. However, there was a clear trend of increased total lipid and triacylglycerol contents in both liver and flesh in fish fed CLA, particularly in fish fed the high oil diets. Finally, CLA was incorporated into tissue lipids, with levels in flesh being 2-fold higher than in liver, but importantly, incorporation in liver was at the expense of saturated and monounsaturated fatty acids whereas in flesh it was at the expense of n-3HUFA.

Animals↗
PubMed1988

Regulation of fatty acid degradation in Escherichia coli: fadR superrepressor mutants are unable to utilize fatty acids as the sole carbon source.

Localized mutagenesis of the fadR region of the Escherichia coli chromosome resulted in the isolation of two classes of fadR regulatory mutants. The first class was constitutive for the fatty acid degradative enzymes and presumably defective for fadR function. The second class was rarer and resulted in the inability to utilize fatty acids as a sole carbon source (Fad-). These fadR superrepressor mutants [fadR(S)] had greatly reduced levels of the beta-oxidative enzymes required for growth on fatty acids. The fadR(S) mutants reverted to Fad+ at a high frequency (10(-5], and the resulting Fad+ revertants were constitutive for expression of the fad enzymes (fadR). Merodiploid analysis showed the fadR(S) allele to be dominant to both fadR+ and fadR alleles.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1985

[Studies on rumen fermentation with special reference to the volatile fatty acid production rate in ewes during reproduction. 2. Production rate of volatile fatty acids and rumen volume].

Methods and results of the measuring of the rumen volume and the passage rate as well as the dependence of the production of volatile fatty acids on the parameters mentioned are described. The correlative relations between rumen volume on the one hand and feed passage on the other hand to the production quotas are investigated. Passage rates and rumen volumes were determined with the help of the isotope dilution method. In the course of reproduction rumen volumes of 7.81, 6.41, 8.91, 7.11 in experiment 1 and 5.41, 5.81, 9.51 and 4.71 in experiment 2 were measured in the sequence early stage of gestation, late stage of gestation, lactation and the period between pregnancies. The average total production of volatile fatty acids within 12 hours amounted to 475 mmol, 265 mmol, 313 mmol and 351 mmol in experiment 1 and 155 mmol, 175 mmol, 271 mmol and 144 mmol in experiment 2 in the same sequence. The average passage duration of the feed through the digestive tract of the ewes was 32.4 h in experiment 1 and 33.6 h in experiment 2. The relatively high feed intake of the ewes resulted in a short passage duration and could be a cause of the low production quotas of the volatile fatty acids.

Animals↗
PubMed2001

Fatty acid absorption in preterms on formulas with and without long-chain polyunsaturated fatty acids and in terms on formulas without these added.

BACKGROUND/OBJECTIVE: Long chain polyunsaturated fatty acids have beneficial effects in preterm neurophysiological development and are semi-essential. Their levels and variation in plasma and red cells in term and preterms are better known than their intestinal absorption. In this paper the absorption of supplemented arachidonic acid (AA) and docosahexaenoic acid (DHA) is evaluated in a preterm group. DESIGN: Four newborn randomized groups were studied. Group T comprised 11 terms on regular formula. Preterms: group P (n=9) was on a classic preterm formula. INTERVENTION: groups PA (n=9) and PB (n=13) were on the same formula but PB contained AA and DHA in similar proportion to breast milk. At 20 days a 3 day metabolic balance was taken for Ca, P(i), Mg, total fat and individual fatty acids (C8-C24, saturated unsaturated). RESULTS: Calcium absorption was (mean+/-s.d.) 51+/-13% in terms. In preterms it was respectively 45+/-18, 38+/-11 and 37+/-21%. Total fat absorption was 92.0+/-8.0% in terms, and from 95.0+/-2.0 to 91.0+/-8.0% in preterms. Absorption of 8:0, 10:0 and 12:0 showed a very high and constant rate despite significant intake differences (715-33 mg/kg/day). Linoleic acid and alpha-linolenic acid were absorbed in the three groups at around 94% regardless of a greater LA intake in group P. Details of absorption (mg/kg/day) were: for AA, intake 17+/-7, fecal excretion 5+/-4, net retention 12+/-5 (75.0+/-18%); for DHA, intake 10+/-3, fecal excretion 3+/-2, net retention 6+/-4 (62.3+/-30%). CONCLUSION: Intestinal absorption of fatty acids is high and is comparable in terms and preterms as regards the studied acids. Longer acids were less well absorbed. The supplemented amounts of AA and DHA were less well absorbed and probably not impairing calcium absorption. SPONSORSHIP: University of Alicante, University of Miguel Hernández.

Arachidonic Acid↗
PubMed1996

Modification of fatty acid composition by over- and antisense-expression of a microsomal omega-3 fatty acid desaturase gene in transgenic tobacco.

omega-3 fatty acid desaturases, which catalyse the conversion of linoleic acid (18:2) to linolenic acid (18:3) in lipids, are located in the microsomes and plastid membranes. Transgenic tobacco plants were produced that express the transcripts of a tobacco microsomal omega-3 fatty acid desaturase gene (NtFad3) in antisense and sense orientations under the control of the cauliflower mosaic virus 35S promoter. The antisense construct has the 0.5-kb fragment of the NtFad3 cDNA containing a 3'-flanking region and a part of the coding region in antisense orientation. The antisense-transformant lines showed decreases of the steady-state NtFad3 mRNA level to 30% of the control plants. In these lines, the 18:3 content decreased to about 80% in root tissues and to about 70-80% in leaf tissues when compared with the control plants. The sense construct has the 1.4-kb full-length cDNA of NtFad3. In one of the sense-transformant lines, the NtFad3 mRNA level increased 8 times when compared with that of the control plants. In this line, the 18:3 content increased by about 1.5-fold in root tissues and by about 1.1-fold in leaf tissues. These results indicate that the up- and down-regulation of the transcript level in the microsomal omega-3 fatty acid desaturase gene is useful to modify the 18:3 content in the vegetative tissues of higher plants.

Antisense Elements (Genetics)↗
PubMed1991

The anti-diabetogenic effect of essential fatty acid deficiency in multiple low-dose streptozotocin-treated mice persists if essential fatty acid repletion occurs outside of a brief window of susceptibility.

We have previously shown that essential fatty acid deficiency prevents diabetes mellitus and ameliorates insulitis in multiple low-dose streptozotocin-treated male CD-1 mice and that repletion with 99% pure methyl linoleate 3 days after the last injection causes diabetes. In the present study, we examined whether repletion of low-dose streptozotocin-treated deficient mice will cause diabetes whenever repletion occurs. Essential fatty acid deficiency was induced by dietary manipulation and was confirmed biochemically. Groups of deficient mice were repleted 6 h, 1 week, 2 weeks, 4 weeks and 8 weeks after the last low-dose streptozotocin treatment; the incidence of diabetes (i.e., non-fasting plasma glucose levels greater than 11.2 mmol/l) and group mean plasma glucose levels were 93% (19.4 mmol/l), 37% (14.8 mmol/l), 40% (13.7 mmol/l), 20% (9.0 mmol/l), and 8% (7.8 mmol/l) respectively. The incidence and mean glucose levels for low-dose streptozotocin-induced control chow-fed and non-repleted essential fatty acid deficient CD-1 mice were 100% (30.2 mmol/l) and 0% (4.2 mmol/l). The incidence and severity of insulitis also decreased with increasing repletion intervals. These results demonstrate a brief window of susceptibility of less than 8 weeks duration during which repletion will initiate an autoimmune response directed at low-dose streptozotocin-induced Beta-cell neoantigens in low-dose streptozotocin-treated essential fatty acid deficient mice.

Animals↗
PubMed1975

Effect of human chorionic gonadotropin on blood free fatty acids, glucose and on the release of free fatty acids from subcutaneous adipose tissue in various groups of newborn and adults.

After administration of human chorionic gonadotropin (HCG; 500 IU/kg intramuscularly), the blood concentration of free fatty acids increases within 30 min in 1-day-old full-term, premature and small-for-data newborns. This effect does not appear in 1-day-old newborns of diabetic mothers with insulin-dependent diabetes, in 7-day-old newborns nor in adults. Glucose concentration rises in all groups of newborns, and no effect is observed in adults. In the in vitro study, HCG increases lipolysis in newborns' adipose tissue. This effect was not observed in adults.

Adipose Tissue↗
PubMed1995

Fatty acid oxidation in peripheral blood cells: characterization and use for the diagnosis of defects of fatty acid oxidation.

Disorders of mitochondrial fatty acid oxidation are increasingly recognized as an important group of inborn errors of metabolism that are associated with a significant, but easily preventable, morbidity and mortality in children. However, diagnosis is often delayed because there is no easily applied method that detects all defects. Therefore, we have characterized the acylcarnitine intermediates of fatty acid oxidation in peripheral blood cells from healthy control volunteers and patients with four different defects. After selective permeabilization with histone II AS, a novel permeabilizing agent, the cells were incubated with [U-14C]hexadecanoate and beta-oxidation flux and the acylcarnitine esters formed were measured. Blood cells from the control population produced large amounts of 3-hydroxyacylcarnitines and 2-enoylcarnitine esters, in addition to saturated acylcarnitine esters. This result is different from that found in other tissues (fibroblasts and muscle), where only saturated acylcarnitine esters could be detected. In blood cells from patients with defects of enzymes involved in long-chain fatty acid oxidation, flux was significantly reduced at 15 to 20% of control values (7.1 +/- 2.3 nmol C2 units formed per minute per International Unit of citrate synthase activity). There was a characteristic accumulation of acylcarnitines that was pathognomonic for the site of the defect. Thus, analysis of beta-oxidation intermediates from blood cells allows unequivocal identification of the four most common beta-oxidation defects.

Acylation↗
PubMed1992

Mechanism of free fatty acid transfer from rat heart fatty acid-binding protein to phospholipid membranes. Evidence for a collisional process.

Fatty acid binding proteins (FABP) are a family of low molecular weight proteins found in many tissues that actively utilize free fatty acids (ffa). FABP would be expected to have a particularly important role in the heart, where over 80% of energy requirements are derived from oxidation of long chain fatty acids. The precise physiological function of heart FABP (H-FABP) has not been definitively identified, although it is thought to play a role in intracellular ffa transport. To examine the possible role of H-FABP in cardiac myocyte transfer of ffa, we examined the transfer of fluorescent anthroyloxy ffa (AOffa) from H-FABP to model phospholipid membranes, using a resonance energy transfer assay. In contrast to previous observations of ffa transfer from liver FABP and from membranes, transfer from H-FABP to membranes appears to occur by a different mechanism. AO-palmitate (16:0) transfer was 1.5-fold slower than AO-stearate (18:0) transfer, and mono-unsaturation did not affect the transfer rate. The AOffa transfer rate from H-FABP increased with increasing ionic strength and decreased slightly between pH 7 and 9. These results suggest that the rate of ffa transfer from H-FABP to membranes is independent of the ffa aqueous solubility. Thermodynamic analysis showed that the free energy of activation for the ffa transfer process arises primarily from an enthalpic component, with only a small entropic contribution, again suggesting the lack of an aqueous phase route of ffa delivery. Finally, the ffa transfer rate was found to be directly dependent on the concentration of acceptor membranes. These data therefore suggest that transfer of AOffa from H-FABP to membranes may occur via collisional interactions between the protein and membranes.

Animals↗
PubMed1993

Effects of insulin on fatty acid reesterification in healthy subjects.

The effects of insulin on triacylglycerol/fatty acid cycling (fatty acid reesterification) were studied in 12 normal subjects during euglycemic hyperinsulinemia with the use of stable isotope dilution analysis ([2H5]glycerol and [1-13C]palmitate) in combination with indirect calorimetry. During basal conditions, 5.6 +/- 0.6 mumol.kg-1 x min-1 of fatty acid were released of which approximately 3.3 mumol.kg-1 x min-1 were oxidized and approximately 2.2 mumol.kg-1 x min-1 were reesterified. A minority of the recycled fatty acid, (0.8 +/- 0.4 mumol.kg-1 x min-1) never left the intracellular space before being reesterified (intracellular triacylglycerol/fatty acid cycling), whereas the majority (1.2 +/- 0.4 mumol.kg-1 x min-1) were first released into the extracellular space and then reesterified in various organs (extracellular triacylglycerol/fatty acid cycling). In response to insulin, fatty acid release declined by 71% (from 5.6 +/- 0.6 to 1.6 +/- 0.2 mumol.kg-1 x min-1). Fatty acid oxidation (measured by indirect calorimetry) declined by 55% (from 3.3 +/- 0.3 to 1.5 +/- 0.3 mumol.kg-1 x min-1) and total triacylglycerol/fatty acid cycling was completely suppressed (from 2.2 to 0.0 mumol.kg-1 x min-1). Fatty acid release, oxidation, total and extracellular triacylglycerol/fatty acid cycling all correlated positively with plasma fatty acid concentrations. These data showed that insulin profoundly suppressed fatty acid release, oxidation as well as reesterification of those fatty acids that had entered the extracellular compartment. They suggested that physiological concentrations of insulin suppressed extracellular fatty acid reesterification primarily by inhibiting lipolysis.

Adult↗
PubMed1997

Effect of maternal dietary n-3 fatty acids on the accretion of long-chain polyunsaturated fatty acids in the tissues of developing chick embryo.

The effect of maternal diets on the accretion of n-3 and n-6 polyunsaturated fatty acids in the brain and liver tissue of developing chick embryos was investigated. Hens were fed diets containing high (HLNA) or low levels of 18:3n-3 (LLNA). The HLNA diet increased (p < 0.05) the content of the 18:3n-3, 20:5n-3 and 22:6n-3 in the yolk lipids with a concomitant reduction (p < 0.005) in 20:4n-6. Diet and time significantly (p < 0.05) affected the transfer of 22:6n-3 (docosahexaenoic acid, DHA) and 20:4n-6 acid from the HLNA and LLNA yolk lipid. In the brain of HLNA chick embryos, a diet- and time-associated increase (p < 0.05) in the phospholipid content was observed. In the brain of HLNA and LLNA embryos, DHA levels increased (p < 0.05) from day 15 to the day of hatching, with a concomitant reduction (p < 0.05) in the liver. The accretion of arachidonic acid plateaued on day 15 in the brain of HLNA and LLNA embryos.

Animal Nutritional Physiological Phenomena↗
PubMed2002

Effects of calcium salts of fatty acids and calcium salt of methionine hydroxy analogue on plasma prostaglandin F2alpha metabolite and milk fatty acid profiles in late lactation Holstein-Friesian cows.

Effects of a dietary lipid supplement containing calcium salts of fatty acids and methionine hydroxy analogue on plasma prostaglandin F2alpha (PGF2alpha) metabolite (PGFM) and milk fatty acid profiles were examined in 40 late lactation, nonpregnant, Holstein-Friesian cows for a period of 70 days. Effects on milk production, milk composition, and blood metabolites were also examined. Cows were paired on the basis of lactation number (first lactation, n = 8; second lactation, n = 32) and randomly assigned from within pairs to one of two dietary treatments: unsupplemented control (C) or 400 g per cow per day of the lipid supplement (S). Cows receiving the supplement had higher (P < 0.05) total milk production, total fat production (kg), and total lactose production (kg). Plasma cholesterol was significantly higher (P < 0.01) after 30 days of treatment in cows receiving the supplement. Cows receiving the supplement had lower (P < 0.01) concentrations of short chain milk fatty acids (C4:0 to C14:1) and higher concentrations of long chain fatty acids (C18:1 and C18:2; P < 0.01) than control animals. Oxytocin-induced prostaglandin release on Day 16 postovulation was increased (P < 0.01) in cows receiving the supplement. In conclusion, supplementation with calcium salts of fatty acids and methionine hydroxy analogue significantly increased milk yield and plasma PGFM.

Animals↗
PubMed1990

Fatty acid and enzymatic compositional changes in the pancreas of rats fed dietary n-3 and n-6 polyunsaturated fatty acids.

The influence of n-3 and n-6 PUFA on the fatty acid composition and the enzyme content of zymogen granules of the normal exocrine pancreas was tested on rats. The animals were fed on different diets comprising 5% fish oil (FO), safflower oil (SFO), and evening primrose oil (EPO) used singly or in combination as dietary fats. The results were compared with those from animals fed 5% hydrogenated beef tallow (HBT). The fatty acid composition and digestive enzyme content were analyzed after a 6-wk feeding period. Differences in the pancreatic fatty acid profiles were related to the fatty acid composition of the ingested fats. Equivalent levels of n-3 fatty acids and 20:3n-6 were obtained with either EPO or FO fed singly or in combination. Similar results were observed with SFO/FO. Higher C20:3n-6/C20:4n-6 ratios were obtained with the oil mixtures. An increase in amylase levels, but a decrease in serine protease (Band 21 kdalton) levels, was associated with EPO. An elevation in procarboxypeptidase levels paralleled an increase in 18:0 levels, whereas the proportion of lipase (Band 49 kdalton) varied inversely with the proportion of C20:3n-6. The SFO/FO mixture elevated the proportions of protease II and proelastase. These results suggest that specific fatty acids influence the proportion of specific digestive enzymes in the zymogen granules.

Analysis of Variance↗