PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “FATTY ACIDS, RADIOACTIVE”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed1997

Trypanosoma cruzi: nitrogenous-base-containing phosphatides in trypomastigote forms--isolation and chemical analysis.

In trypanosomatids, little is known about the biosynthetic pathways involved in the metabolism of ethanolamine. In an attempt to clarify this point, an exhaustive analysis of the chloroform:methanol extract of T. cruzi trypomastigotes metabolically labeled with [14C]ethanolamine, in comparison with the lipids from [3H]palmitic acid-incorporated parasites, was performed. In both cases, phosphatidylethanolamine and lysophosphatidylethanolamine were detected, while phosphatidylcholine and lysophosphatidylcholine were only labeled with the fatty acid precursor. However, dimethylphosphatidylethanolamine was isolated from parasites labeled with the base precursor, indicating the ability of trypanosomes to methylate phosphatidylethanolamine to dimethylphosphatidylethanolamine. Fatty acids of the labeled phospholipids were analyzed by reverse-phase thin-layer chromatography and fluorography. Interestingly, phospholipids from the trypomastigote stage show palmitic acid (C16:0) and stearic acid (C18:0) as the only labeled components. The same saturated fatty acids were found free and as components of the radioactive triglycerides. No unsaturated fatty acids were detected, in accordance with the results obtained with inositolphospholipids. Conversely, when the fatty acids of phospholipids purified from nonlabeled parasites were analyzed by gas-liquid chromatography and gas-liquid chromatography-mass spectrometry, C18:1 was also detected. A striking finding was the presence of a considerable amount of free lignoceric acid (C24:0). Also, the C24:0 fatty acid was identified in the triglyceride fraction and as a component of phosphatidylcholine. The limited capacity of trypomastigote forms to elongate fatty acids was determined. In contrast with the results reported for other noninfective forms of the parasite, the absence of unsaturated fatty acids due to a low activity of desaturases was observed.

Animals↗
PubMed1979

[Effect of the streptozotocin diabetes upon the in vivo conversion of [I-14C] gamma-linolenic and dihomo-gamma-linolenic acids into arachidonic acid in rats (author's transl)].

Streptozotocin diabetic rats were administered the same tracer dose of either [1 14C] gamma-linolenic or [1 14C] dihomo-gamma-linolenic acid by stomach tube seven days after streptozotocin injection. They were killed 48 hours later and the radioactivity in individual fatty acids of the liver determined by radio-gas chromatography. Results were compared to those obtained in non diabetic rats similarly prepared. With either radioactive precursor, 14C radioactivity recovered in hepatic dihomo-gamma-linolenic acid was not significantly affected by the diabetic state. On the other hand, 14C radioactivity incorporated into arachidonic acid was considerably decreased in diabetic rats, compared with normal rats, when the weights of hepatic arachidonic acid were the same in the two groups of animals. These results suggest that streptozotocin diabetes causes a partial inhibition of the 5-desaturation of dihomo-gamma-linolenic acid in rat liver in vivo.

8,11,14-Eicosatrienoic Acid↗
PubMed1987

The release of radioactive arachidonate from lipids of red blood cells during prolonged incubations in vitro.

Red blood cells were isolated from rat blood and incubated in the presence of [3H]arachidonate. A sizeable quantity (18%) of the radioactivity was incorporated into red cell lipids, of which phosphatidylcholine was the most highly labelled. Radioactive arachidonate was found at position 2 of this phospholipid. Free fatty acids were removed by washing the cells in solutions containing fatty-acid-free bovine serum albumin. The labelled red cells were then incubated for up to 16 h at 37 degrees C. After 16 h of incubation in saline-buffer-glucose or rat serum, 20 and 26%, respectively, of the total radioactivity was found in free fatty acids, and there were corresponding declines in the percentage radioactivities found in phosphatidylcholine. In the presence of serum, there was a more rapid release of radioactive fatty acid over the 2- to 16-h time course. There was not a significant drop in the phosphate levels of the total red cell phospholipids or phosphatidylcholine after 16 h of incubation and, as a result, there were large declines in the specific radioactivities of phosphatidylcholine. Diacylglycerols were not highly labelled and the action of phospholipase A2 on labelled phosphatidylcholine was indicated. When white blood cells were added to labelled red cells, there was little evidence of white cell involvement in the release of radioactive fatty acid, suggesting that the red cells themselves may be involved in arachidonate release. Red cells may serve as sources of arachidonate, released following hemorrhage in brain and metabolized to form various biologically active eicosanoids.

Animals↗
PubMed2000

Effect of sex and bezafibrate on incorporation of blood borne palmitate into lipids of rat liver nuclei.

The aim of the present study was to investigate whether lipid metabolism in the nuclei is affected by changes in the metabolism of free fatty acids in the liver. The experiments were carried out on 3 groups of rats: 1 - control-male, 2 - female, and 3 - male, treated with bezafibrate (a peroxisome proliferator). The rats received 14C-palmitic acid intravenously. Thirty min later liver samples and blood from the abdominal aorta were taken. The liver nuclei were isolated in sucrose gradient. Lipids were extracted from the nuclei and the liver homogenate and subsequently separated into the following fractions: phospholipids, mono, di- and triacylglycerols, free fatty acids, cholesterol and cholesterol esters. The radioactivity of each fraction was counted. Furthermore, the content of free fatty acids and the fatty acid binding proteins was measured. It was found that radioactivity was present in each lipid fraction obtained from the liver homogenate and from the nuclei. In the female group, the total radioactivity of lipids in the liver homogenate was lower, whereas in the nuclei it was higher in comparison to the male group. The reduction in the radioactivity in the liver was mostly accounted for by decreased radioactivity in the fraction oftriacylglycerols and phospholipids. In the nuclei, the radioactivity of the fraction of phospholipids, free fatty acids and diacylglycerols was elevated. Bezafibrate did not affect the total radioactivity of lipids in the liver and reduced it in the nuclei. In the liver, the drug increased radioactivity mostly in the fraction of phospholipids and reduced it mainly in the fraction of triacylglycerols. In the nuclei, the radioactivity of each lipid fraction examined was reduced. The content of the fraction of free fatty acids in the liver and in the nuclei in the female and in the bezafibrate-treated groups did not differ from the respective value in the control group. The content of fatty acid binding proteins in the nuclei of the female and bezafibrate-treated groups increased in parallel to the elevation in their content in the cytosol. It is concluded that the female sex hormones and bezafibrate influence the transport of selected lipids into the nuclei. The effects seem to be a consequence of the action of these factors directly on the nucleus.

Active Transport, Cell Nucleus↗
PubMed1985

[Effect of streptozotocin diabetes on the in vivo conversion of gamma-linolenic and dihomo-gamma-linolenic 14C acids to arachidonic acid in the rat kidney and in the rat body].

Streptozotocin diabetic rats were administered the same tracer dose of either [1 14C] gamma-linolenic acid or [2 14C] dihomo-gamma-linolenic acid by stomach tube seven days after streptozotocin injection. They were killed 48 hours later and the radioactivity in individual fatty acids of the kidneys and the whole animal determined by radio-gas chromatography. Results were compared to those obtained in non diabetic rats similarly prepared. With either radioactive precursor, 14C radioactivity incorporated into arachidonic acid, only as specific radioactivity of this acid, were considerably decreased in diabetic rats compared with normal rats, while the weights of renal and whole rat arachidonic acid were the same in the two groups of animals. These results suggest that, in vivo, streptozotocin diabetes causes a partial inhibition of the delta 5-desaturation of dihomo-gamma-linolenic acid, considered as a secondary step in linoleic acid metabolism, both in the kidneys and the whole rat as in the liver.

8,11,14-Eicosatrienoic Acid↗
PubMed1986

Desaturation of fatty acids in Trypanosoma cruzi.

Uptake and metabolism of saturated (16:0, 18:0) and unsaturated [18:1(n-9), 18:2(n-6), 18:3(n-3)] fatty acids by cultured epimastigotes of Trypanosoma cruzi were studied. Between 17.5 and 33.5% of the total radioactivity of [1-14C]labeled fatty acids initially added to the culture medium was incorporated into the lipids of T. cruzi and mostly choline and ethanolamine phospholipids. As demonstrated by argentation thin layer chromatography, gas liquid chromatography and ozonolysis of the fatty acids synthesized, exogenous palmitic acid was elongated to stearic acid, and the latter was desaturated to oleic acid and 18:2 fatty acid. The 18:2 fatty acid was tentatively identified as linoleic acid with the first bond in the delta 9 position and the second bond toward the terminal methyl end. Exogenous stearic acid was also desaturated to oleic and 18:2 fatty acid, while oleic acid was only converted into 18:2. All of the saturated and unsaturated fatty acids investigated were also converted to a small extent (2-4%) into polyunsaturated fatty acids. No radioactive aldehyde methyl ester fragments of less than nine carbon atoms were detected after ozonolysis of any of the fatty acids studied. These results demonstrate the existence of delta 9 and either delta 12 or delta 15 desaturases, or both, in T. cruzi and suggest that delta 6 desaturase or other desaturases of the animal type are likely absent in cultured forms of this organism.

Animals↗
PubMedDate not supplied

Expression of a functionally active cardiac fatty acid-binding protein in the yeast, Saccharomyces cerevisiae.

The unicellular eukaryotic microorganism, Saccharomyces cerevisiae, transformed with a plasmid containing a cDNA fragment encoding bovine heart fatty acid-binding protein (H-FABP) under the control of the inducible yeast GAL10 promoter, expressed FABP during growth on galactose. The maximum level of immunoreactive FABP, identical in size to native protein as judged from SDS-polyacrylamide gel electrophoresis, was reached after approximately 16 hours of induction. Analysis of particulate and soluble subcellular fractions showed that FABP was exclusively associated with the cytosol. FABP expressed in yeast cells was functional as was demonstrated by its capacity to bind 14C-oleic acid in an in vitro assay. Growth of the transformants on galactose as the carbon source was significantly retarded at 37 degrees C. Whereas the fatty acid pattern of total lipids was not altered in transformed cells, desaturation of exogenously added 14C-palmitic acid was significantly reduced both at 30 and 37 degrees C. The lowest percentage of radioactively labeled unsaturated fatty acids was found in the phospholipid fraction.

Carbon Radioisotopes↗
PubMed1979

New experiments of biotin enzymes.

The objects of structural studies on biotin-enzymes were acetyl CoA-carboxylase and pyruvate carboxylase of Saccharomyces cerevisiae and beta-methylcrotonyl CoA-carboxylase and acetyl CoA-carboxylase of Achromobacter IV S. It was found that these enzymes can be arranged in three groups. In the first group, as represented by acetyl CoA-carboxylase of Achromobacter, the active enzyme could be resolved in three types of functional components: (1) the biotin-carboxyl carrier protein, (2) the biotin carboxylase, and (3) the carboxyl transferase. In the second group, as represented by beta-methylcrotonyl CoA-carboxylase from Achromobacter only two types of polypeptides are present. The one carries the biotin carboxylase activity together with the biotin-carboxyl-carrier protein, the other one carries the carboxyl transferase activity. In this third group, as represented by the two enzymes of yeast, all three catalytic functions are incorporated in one multifunctional polypeptide chain. The evolution of the different enzymes is discussed. The animal tissues acetyl CoA-carboxylase is under metabolic control, as known from previous studies. It thus has to be expected that the levels of malonyl CoA in livers of rats in all states of depressed fatty acid synthesis are much lower than under normal conditions because the carboxylation of acetyl CoA is strongly reduced and cannot keep pace with the consumption of malonyl CoA by fatty acid synthetase. A new highly sensitive assay method for malonyl CoA was developed which uses tritiated NADPH and measures the incorporation of radioactivity into the fatty acids formed from malonyl CoA in the presence of purified fatty acid synthetase. The application of this method to liver extracts showed that the level of malonyl CoA which amounts to about 7 nmoles per gram of wet liver drops to less than 10% within a starvation period of 24 hr and even further if the starvation period is extended to 48 hr. A low malonyl CoA concentration is also found in the alloxan diabetic animals and in animals being fed a fatty diet after starvation. On the other hand, feeding a carbohydrate rich diet leads to malonyl CoA levels surpassing the levels found after feeding a balanced diet. These observations reconfirm the concept that fatty acid synthesis is principally regulated by the carboxylation of acetyl CoA.

Acetyl-CoA Carboxylase↗
PubMed1984

Phospholipids as acyl donors to membrane proteins of Mycoplasma capricolum.

Mycoplasma capricolum, a procaryotic sterol and fatty acid auxotroph, contains a large number of membrane proteins covalently modified by both saturated and unsaturated fatty acids (Dahl, C.E., Dahl, J.S., and Bloch, K. (1983) J. Biol. Chem. 258, 11814-11818). Pulse-chase experiments show that the radioactivity in the fatty acid moieties of the acyl proteins increases rather than decreases during a 4.5-h incubation period suggesting that a large intracellular pool of metabolites such as phospholipid serves as the donor for protein acylation. We find that cells incubated for 4 h in a growth medium containing [3H]palmitate-labeled phosphatidylglycerol or 2-[3H]palmitoyl dipalmitoylphosphatidylcholine show the same labeling pattern as cells incubated for 4 h in a complete growth medium with [3H]palmitate. Exogenously added phospholipids are not hydrolyzed to free fatty acid during the labeling period. Acylation of proteins is inhibited in cells treated with chloramphenicol showing that there is no pool of proacyl protein in the cell. Labeling of membrane proteins also occurs with [3H]glycerol. Glycerol is incorporated primarily into the same proteins as oleate suggesting that acylation by unsaturated fatty acid may involve a protein bound diglyceride moiety. Palmitate, on the other hand, appears to bind to other sites along the polypeptide chain in addition to the diglyceride moiety.

Acylation↗
PubMed1982

Phospholipid biosynthesis in human platelets. Formation of phosphatidylcholine from 1-acyl lysophosphatidylcholine by acyl-CoA:1-acyl-sn-glycero-3-phosphocholine acyltransferase.

Arachidonic acid and other fatty acids are taken up by human platelets from plasma and incorporated into membrane phospholipids. However, little is known about the mechanism and specificity of the various steps of fatty acid insertion into phospholipid. Previous findings from this laboratory have shown that the incorporation of radioactive C20-unsaturated fatty acids (arachidonic, 8,11,14-eicosatrienoic, and 5,8,11,14,17-eicosapentaenoic) into the phospholipids of "resting"p platelets is more rapid than that of the radioactive C16- and C18-saturated and unsaturated fatty acids. We now provide evidence that human platelet microsomes contain acyl-CoA:1-acyl-sn-glycero-3-phosphocholine acyltransferase. The enzyme preparation has a pH optimum of 7.0. Activity is insensitive to 1 mM EDTA and is inhibited 37% by 1 mM Ca2+ and 20% by 1 mM Mg2+. Maximal activity is observed at 100 microM 1-acyl lysophosphatidylcholine at several concentrations of fatty acyl-CoA esters. Apparent Km values from 1.05 to 5.70 microM were obtained for saturated and unsaturated fatty acyl group donors in the presence of 100 microM 1-acyl lysophosphatidylcholine as fatty acyl group acceptor. Comparison of the apparent Vmax values showed that unsaturated CoA esters were transferred more rapidly to 1-acyl lysophosphatidylcholine than saturated CoA esters. Oleate, linoleate, and arachidonate, the major unsaturated fatty acids in platelet phosphatidylcholine, were transferred at similar rates. 8,11,14-eicosatrienoate was transferred about two times faster than these three fatty acyl groups. The data indicate that the incorporation of unsaturated fatty acids into phosphatidylcholine by human platelets occurs via reacylation of 1-acyl lysophosphatidylcholine.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1976

Biosynthesis of fatty acids by the carp, Cyprinus carpio L., in relation to environmental temperature.

Incorporation in vivo of sodium 1-14C-acetate into different lipid classes and fatty acids of total lipids and phospholipids of warm adapted and cold adapted carp livers was studied at 5 C and 22 C, respectively. The fatty acid composition of total lipids and phospholipids was also determined. The level of long chain polyunsaturated fatty acids in both total lipid and phospholipid fraction was higher in cold adapted fish than in warm adapted ones. The distribution of radioactivity among different lipid classes depended only on the actual incorporation of the temperature history of the animals. Livers of fish incorporated a higher percentage of radioactivity into long chain polyunsaturated fatty acids of total lipids and phospholipids in 5 C than in 22 C. The distribution of radioactivity among different fatty acids was dependent on the experimental temperature rather than on the temperature to which the fish were adapted. The results suggest that fish are able to adjust the pattern of the biosynthesis of fatty acids very rapidly to the prevailing temperature and to assure by this way the proper physicochemical properties of their membranes. The possible mechanisms involved in this rapid response are discussed.

Acclimatization↗
PubMed1976

Galactolipid Synthesis in Vicia faba Leaves: II. Formation and Desaturation of Long Chain Fatty Acids in Phosphatidylcholine, Phosphatidylglycerol, and the Galactolipids.

The labeling kinetics of the fatty acids of phosphatidylcholine (PC), phosphatidylglycerol (PG), monogalactosyldiglyceride (MGDG), and digalactosyldiglyceride (DGDG) were examined after (14)CO(2) feeding and incubation of leaf discs of Vicia faba over 72 hours in continuous light. The results indicate a rapid accumulation and turnover of radioactivity into PC and PG fatty acids (oleic acid in PC and oleic and palmitic acids in PG). Radioactivity accumulates in MGDG and DGDG fatty acids much more slowly and continuously over 72 hours. Most of this activity is found in linoleic and linolenic acids; very little activity is found in the more saturated fatty acids. Little or no desaturation occurs in situ in conjunction with the galactolipids. The results suggest that PC and PG may act as "carriers" for MGDG and DGDG fatty acid synthesis. Analyses of the labeling patterns of the molecular species of MGDG after (14)CO(2) and (14)C-acetate feeding confirm that MGDG is formed by galactosylation of a preformed diglyceride containing predominantly unsaturated fatty acids.

Journal Article↗
PubMed1998

Oxidative metabolism of [1-14C] mono-trans isomers of linoleic and alpha-linolenic acids in the rat.

Trans polyunsaturated fatty acids are formed during processing of vegetable oils such as deodorization and frying. The oxidative metabolism of linoleic and alpha-linolenic acids and of their mono-trans isomers (9cis,12trans-18:2, 9trans,12cis-18:2 and 9cis, 12cis,15trans-18:3, 9trans,12cis,15cis-18:3, respectively) was studied in fasting rats. A single dose of 18.5 MBq of each [1-14C] labelled fatty acid (260 microg) was orally given to the animals. The 14CO2 expired was monitored during 24 h. Radioactive countings of the CO2-trapping agent were performed at regular intervals up to 24 h after oral administration of the radiolabelled fatty acid. Radioactive countings were also performed on several tissues (liver, heart, brain, kidneys, sus-epidydimal fat, gastrocnemian muscle, gastrointestinal tract and carcass). The 14CO2 production 24 h after oral administration of the fatty acid ranged from 55.5% to 68.7% of the radioactivity administered for the C18:2 isomers and from 69.7% to 73.5% for the C18:3 fatty acids. From 6 to 24 h, 14CO2 recovery was significantly higher after oral administration of 9cis, 12trans-18:2 than after giving both other octadecadienoic isomers. 14C retention per gram of tissue in the liver and in the heart was significantly lower after feeding 9cis,12trans-18:2 than after administration of both other C18:2 isomers. 14C retention per gram of tissue in the muscle was significantly lower after administration of both trans C18:2 isomers compared to linoleic acid. Neither 14CO2 recoveries nor 14C retentions were significantly different after administration of the three octadecatrienoic acids. The difference observed in 14CO2 recovery within the dienes was probably not due to a higher specificity of the enzymes involved in the beta-oxidation sequence for the Delta12trans double bond, as previously reported. Indeed, due to the labelling of the fatty acids on the carboxyl end, 14C values recorded in the CO2-trapping agent were only due to the first cycle of beta-oxidation.

Administration, Oral↗
PubMed1983

Formation of diacylglycerol and degradation of phosphatidylinositol induced in rat lymphocytes by non-esterified oleic or linoleic acid.

Rat spleen lymphocytes were incubated for 3 h with [14C]arachidonic acid in foetal calf serum. It was found that arachidonic acid distributed into phospholipids in the order phosphatidylcholine greater than phosphatidylethanolamine greater than phosphatidylinositol. After labelling with arachidonic acid the lymphocytes were washed, and incubated for up to 2 h with non-radioactive palmitic, oleic or linoleic acid dissolved in ethanol. The presence of ethanol or palmitic acid during a 2 h post-incubation had little effect on the amount of radioactivity found in different lipid fractions. Both oleic acid and linoleic acid, however, brought about an accumulation (up to 8-fold) of radioactivity in the diacylglycerol fraction. These fatty acids also brought about a change of radioactivity in several phospholipids, notably in phosphatidylinositol, which lost more than 50% of its counts during the 2 h incubation. Although maximum effects were seen at 2 h, diacylglycerol radioactivity was increased by 100% within 5 min after adding the fatty acids. The minimum concentration of fatty acids used (50 microM) gave an almost maximum response. The results indicate that unsaturated fatty acids may activate phosphatidylinositol phosphodiesterase in lymphocytes, as they do in brain. The possibility that a phospholipase A is activated is discussed. Possible implications for any experiments in which cells are incubated with fatty acids are pointed out.

Animals↗