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PubMed1976

Free fatty acid metabolism in the forearm at rest: muscle uptake and adipose tissue release of free fatty acids.

Free fatty acid (FFA) metabolism in forearm skeletal muscle at rest was studied during continuous intrabrachial arterial ininfusion of [1-14C] oleic acid in 14 normal subjects in the postabsorptive state. Total oleic acid uptake by muscle accounted for at least 65% and perhaps as much as 86% of the measured O2 consumption. The respiratory quotient (0.74) indicated predominant oxidation of lipid. Glucose was a minor substrate for oxidation. Concentrations of six individual free fatty acids were measured in arterial (A), deep venous (DV), and superficial venous (SV) plasma in 25 subjects. There were positive A-DV differences, reflecting net muscle uptake, for each FFA. The extraction ratio (A-DV)/A was greatest for oleic acid. Output of each free fatty acid from subcutaneous adipose tissue was proportional to its arterial concentration, except for stearic acid. There was no stearic acid output. Correction of (A-DV)/A to account for contribution of perimuscular adipose tissue to FFA in DV led to the conclusion that oleic acid was preferentially extracted from arterial blood by forearm muscle. It accounted for 51% of the total FFA uptake, although it comprised only 43% of total FFA in arterial plasma. Total FFA uptake by muscle was more than sufficient to account for all of the measured O2 consumption, suggesting that some of the extracted FFA may be stored in muscle for oxidation at a latter time.

Adipose Tissue↗
PubMed1996

A model cell line to study regulation of stearoyl-CoA desaturase gene 1 expression by insulin and polyunsaturated fatty acids.

Insulin and polyunsaturated fatty acids (PUFAs) regulate the expression of SCD1 gene in mouse liver. Accordingly, we examined the insulin and PUFA regulation of SCD1 gene expression in H2.35 cells. The levels of SCD1 mRNA in H2.35 cells increased at the restrictive temperature of 39 degrees C, when the glucose-containing medium was supplemented with insulin. The insulin-stimulated expression of SCD1 mRNA was significantly blunted when the induction medium was supplemented with linolenic acid (18:2n-3) and arachidonic acid (20:4n-6). Stearic acid (18:0n-9) and oleic acid (18:1n-9) were without dramatic effects. The effect of insulin and PUFAs on a transfected SCD1 fusion gene (SCD1.CAT4.3) was also examined in H2.35 cells. Whereas insulin stimulated SCD1.CAT4.3 expression, arachidonic acid significantly decreased SCD1.CAT4.3 activity. These studies suggest that insulin and PUFAs regulate SCD1 gene transcription via regulatory DNA sequences flanking the 5' end of the gene.

Actins↗
PubMed2000

Identification of triacylglycerol species from high-saturated sunflower (Helianthus annuus) mutants.

The triacylglycerol (TAG) composition of oils from new high-saturated sunflower lines has been studied by means of GLC. The TAG profiles have been compared with the TAG reconstruction made after lipase hydrolysis (according to the 2-random 1,3-random theory). New TAG species with asclepic (cis,Delta11-octadecenoic acid, isomer of oleic acid), araquidic, or behenic acids have been synthesized and identified in oils from mutant lines. The TAG molecular species that contain asclepic acid instead of oleic acid have a longer retention time. Because each mutant oil has a specific TAG GLC pattern, this method could be used for a more precise validation of oil type than current fatty acid methyl ester analysis. The comparison of the results obtained by GLC with the reconstruction after pancreatic lipase hydrolysis shows, in general, a good agreement between both methods. However, results shown in this paper show that this is not always the case. TAG species containing two molecules of linoleic acid show a higher presence of palmitic or stearic acid than could be expected from a random distribution. The abundance of SLL increased in proportion to the stearic acid content of the oil, and the amount of TAG species with three unsaturated fatty acids (LLL or OLL) was therefore reduced.

Chromatography, Gas↗
PubMed1983

A double blind cross-over study on the effects of ORG OD14 compared to estradiol valerate and placebo on the fatty acid composition of serum lecithin and cholesterol ester in oophorectomized women.

Twenty-two women, oophorectomized in connection with surgical treatment for cervical carcinoma in clinical stage IB or IIA, were given ORG OD14 [(7 alpha,17 alpha)17-hydroxy-7-methyl-19-norpregn-5-(10)20-yn-3-one; 2.5 mg/day], a placebo, and estradiol valerate (2 mg/day), six weeks each, in a double blind, cross-over study. ORG OD14 is a synthetic steroid for continuous treatment of climacteric symptoms which in traditional bioassays has been shown to have weak estrogenic and progestogenic as well as very weak androgenic-anabolic properties. The aim of this study was to evaluate its effects on serum lecithin as well as on the relative fatty acid composition of serum lecithin and serum cholesterol ester. In serum lecithin, OD14 induced an increase in palmitic acid and a decrease in stearic acid, effects typical of 17-C-alkylated steroids, compared to both placebo and estradiol valerate. Furthermore, there was an increase in linoleic acid and a decrease in both arachidonic and dihomo-gamma-linolenic acid after OD14 administration. This decrease is interpreted as an inhibitory action of the steroid on the mechanisms of elongation and desaturation of linoleic acid and is considered to be an androgenic influence. The relative decrease is further accentuated by the decrease in total serum lecithin induced by OD14. Since these fatty acids are the major precursors for prostaglandin synthesis, these findings might have relevance in that context.

Adult↗
PubMed2001

Menopause-induced changes in lipid fractions and total fatty acids in plasma.

UNLABELLED: The purpose of the present work was to evaluate the changes induced by the menopause in plasma lipids and total fatty acids. METHODS: 35 post-menopausal and 25 non-postmenopausal women were included in the study. Plasma triglycerides (TG), total cholesterol (TC) and HDL-C concentrations were detemined enzymatically. Plasma fatty acids were determined by capillary gas chromatography. RESULTS: Total cholesterol was higher (p < 0.05) in the postmenopausal women (6.18 +/- 0.77 mmol/l vs. 5.21 +/- 0.85 mmol/l). No significant changes were observed, however, in TG, HDL-C or LDL-C. The study of plasma fatty acids showed the post-menopausal women to have raised levels (p < 0.05) of stearic acid (C18:0), oleic acid (C18:1), and decrease of arachidonic acid (C20:4). Also noteworthy was the significant decrease (p < 0.001) of the desaturation index D5 (3.82 +/- 1.75) in the post-menopausal women. The SHBG level was lower (p <0.001) in the post-menopausal women (55.98 +/- 20nmol/l) than in the non-menopausal women (68.36 +/- 30 nmol/l). Multivariate analysis revealed correlation between menopause and SHBG (r = -0.3904, p < 0.05), D5 (r = -0.500, p < 0.001), TC (r = 0.3137, p <0.05), stearic acid (r = 03564, p < 0.05) and oleic acid (r = 0.2954, p < 0.05). CONCLUSION: In post-menopausal women, as well as higher total cholesterol, the alterations in plasma fatty acids may constitute an important risk factor for cardiovascular diseases.

Adult↗
PubMed1995

Isolation, chemical structures and biological activity of the lipo-chitin oligosaccharide nodulation signals from Rhizobium etli.

Rhizobium etli is a microsymbiont of plants of the genus Phaseolus. Using mass spectrometry we have identified the lipo-chitin oligosaccharides (LCOs) that are produced by R. etli strain CE3. They are N-acetylglucosamine pentasaccharides of which the non-reducing residue is N-methylated and N-acylated with cis-vaccenic acid (C18:1) or stearic acid (C18:0) and carries a carbamoyl group at C4. The reducing residue is substituted at the C6 position with O-acetylfucose. Analysis of their biological activity on the host plant Phaseolus vulgaris shows that these LCOs can elicit the formation of nodule primordia which develop to the stage where vascular bundles are formed. The formation of complete nodule structures, including an organized vascular tissue, is never observed. Considering the very close resemblance of the R. etli LCO structures to those of R. loti (I. M. López-Lara, J. D. J. van den Berg, J. E. Thomas Oates, J. Glushka, B. J. J. Lugtenberg, H. P. Spaink, Mol Microbiol 15: 627-638, 1995) we tested the ability of R. etli strains to nodulate various Lotus species and of R. loti to nodulate P. vulgaris. The results show that R. etli is indeed able to nodulate Lotus plants. However, several Lotus species are only nodulated when an additional flavonoid independent transcription activator (FITA) nodD gene is provided. Phaseolus plants can also be nodulated by R. loti bacteria, but only when the bacteria contain a FITA nodD gene. Apparently, the type of nod gene inducers secreted by the plants is the major basis for the separation of Phaseolus and Lotus into different cross inoculation groups.

Acetylglucosamine↗
PubMed2000

Steroid 5alpha-reductase inhibitory activity and hair regrowth effects of an extract from Boehmeria nipononivea.

The acetone extract of Boehmeria nipononivea showed both potent 5alpha-reductase inhibitory activity and hair regrowth promotion effects on mice. 5alpha-Reductase inhibitory activity-guided fractionation led to six active fatty acids: alpha-linolenic, linoleic, palmitic, elaidic, oleic and stearic acids. The extract of B. nipononivea, and alphalinolenic, elaidic and stearic acids exhibited a hair regrowth effect.

5-alpha Reductase Inhibitors↗
PubMed1999

Fatty acid delta9-desaturation in the Triatoma infestans fat body: response to food and trehalose administrations.

The effects of food intake and carbohydrate administration on fatty acid delta9-desaturation were investigated in isolated microsomes from Triatoma infestans fat body. Fifth instar nymphs, which were solely blood-fed just after the molt and then fasted, were used as controls and for determination of optimal assay conditions. Both [1-14C]palmitic and [1-14C]stearic acids in a medium containing ATP, CoA, MgCl2, NADH, NaF, and O2 were tested. For the control group, optimal conditions were a pH of 6.8-7.2, an incubation temperature of 29 degrees C, and an incubation time of 10 min. delta9-Desaturation depended on the presence of reduced pyridine dinucleotides; NADH and NADPH were equally efficient. Stearic acid showed a higher apparent Vmax than palmitic acid, but the apparent Km were very similar. When fifth instar nymphs were blood-fed weekly, a marked increase of delta9-desaturation was observed for both acids. Higher desaturation activity was also induced by injection of the carbohydrate trehalose into the hemolymph of fasted nymphs. These results indicate that insect delta9-desaturation, like the mammalian counterpart, is sensitive to dietary changes and carbohydrate administration.

Animals↗
PubMed1993

Effect of nutrients on plasma corticosteroid concentration in cold-stressed rats.

Little is known about the mechanisms as to how nutrients affect plasma corticosteroids in cold-stressed and starved animals. Therefore, cold-stressed rats (maintained at 7 degrees C) were fasted (control) or fed a balanced diet (casein 20 wt%, fat 5 wt%, starch 70 wt% and vitamin-mineral premix 5 wt%) or the following dietary nutrients for 72 h: casein, lard, starch, glycerol, stearic acid, leucine or glutamic acid. The animals were then killed and plasma corticosteroid concentrations (PCC) were determined. PCC were significantly reduced (p < 0.05) in cold-stressed animals fed a balanced diet (16.95 micrograms/100 ml plasma) compared to the fasted cold-stressed controls (FCSC) (24.16 micrograms/100 ml plasma). Additionally, corticosteroid concentrations (micrograms/100 ml plasma) of animals fed the following specific nutrients were also significantly lower than the FCSC values: starch (15.53), lard (12.01), stearic acid (12.74), glycerol (13.32) and leucine (16.03). Casein and glutamic acid did not significantly alter plasma corticosteroid levels relative to the FCSC concentration. It is concluded that certain specific building blocks of nutrient classes, i.e. stearic acid or glycerol, can alter PCC to the same extent as the parent compound (lard), however the individual components of casein, a complex nutrient, i.e. leucine, a ketogenic amino acid, versus glutamic acid, a glycogenic amino acid, may elicit a different PCC effect.

Adrenal Cortex Hormones↗
PubMed2004

Enhanced remote photocatalytic oxidation on surface-fluorinated TiO2.

The mobile nature of active oxygen species generated on the UV-illuminated TiO2 surface is now well-recognized. Surface oxidants not only migrate two-dimensionally but also desorb from the surface to be air-borne oxidants. The remote photocatalytic oxidation (PCO) of stearic acids over the surface-fluorinated TiO2 (F-TiO2) film was carried out in the ambient air to study the effects of fluorination on the desorption of oxidants from the surface. The F-TiO2 film was faced to a stearic acid-coated glass plate separated by a small gap (typically 30 microm), and the photocatalytic degradation of the stearic acid was monitored by Fourier transform infrared measurement or gas-chromatographic CO2 production analysis. Remote photocatalytic degradation of stearic acids was markedly faster with F-TiO2 than with the pure TiO2 film, which indicates that the generation of air-borne oxidants is enhanced over the F-TiO2 surface. The remote PCO activity was higher with a higher surface fluoride concentration, higher UV intensity, and smaller gap. The remote photocatalytic activity of F-TiO2 was maximal at a relative humidity of 50% and did not show any sign of deactivation with repeated reactions. The production of CO2 that evolved as a result of the remote PCO of stearic acids was enhanced when H2O2 vapor was present but was strongly inhibited in the presence of ammonia gas that should scavenge OH radicals. Judging from various evidences, the air-borne oxidants in remote PCO are most likely OH radicals and the surface fluorination of TiO2 seems to facilitate the desorption of OH radicals.

Journal Article↗
PubMed1996

Acute effect of high-fat meals rich in either stearic or myristic acid on hemostatic factors in healthy young men.

Suggestions have been made that saturated fatty acids with 12-18 carbon atoms, stearic acid (18:0) in particular, are prothrombogenic. These suggestions are based mainly on in vitro measurements. In the present study the effect of dietary fats high in stearic or myristic acid (14:0) on plasma triacylglycerol concentrations and key variables of blood aggregation (in vitro and in vivo), coagulation, and fibrinolysis was studied over 24 h in 10 healthy young men. For each dietary fat, two identical high-fat test meals were served: one in the morning (0 h) and one 8 h later, and blood samples were collected at 0, 2, 4, 6, 8, and 24 h. Both fats decreased platelet aggregation compared with fasting values. Stearic fat resulted in a tendency toward lower activity of plasminogen activator inhibitor 1 (PAI-1) than did myristic fat (P < 0.08). PAI-1 was also lower 24 h after consumption of either fat than initially (P < 0.05). Stearic fat, but not myristic fat, tended to cause some increase in factor VII coagulant activity and beta-thromboglobulin after 4 h. In conclusion, an acute prothrombotic effect of fats high in myristic and stearic acid was not confirmed.

Adult↗
PubMed1996

Identification of two molecular species of rat brain phosphatidylcholine that rapidly incorporate and turn over arachidonic acid in vivo.

In vivo rates of arachidonic acid incorporation and turnover were determined for molecular species of rat brain phosphatidylcholine (PtdCho) and phosphatidylinositol (PtdIns). [3H]Arachidonic acid was infused intravenously in pentobarbital-anesthetized rats at a programmed rate to maintain constant plasma specific activity for 2-10 min. At the end of infusion, animals were killed by microwave irradiation, and brain phospholipids were isolated, converted to diacylglycerobenzoates, and resolved as molecular species by reversed-phase HPLC. Most [3H] arachidonate (> 87%) was incorporated into PtdCho and PtdIns, with arachidonic acid at the sn-2 position and with oleic acid (18:1), palmitic acid (16:0), or stearic acid (18:0) at the sn-1 position. However, 10-15% of labeled brain PtdCho eluted in a small peak containing two molecular species with arachidonic acid at the sn-2 position and palmitoleic acid (16:1) or linoleic acid (18:2) at the sn-1 position. Analysis demonstrated that tracer was present in both the 16:1-20:4 and 18:2-20:4 PtdCho species at specific activities 10-40 times that of the other phospholipids. Based on the measured mass of arachidonate in each phospholipid molecular species, half-lives were calculated for arachidonate of < 10 min in 16:1-20:4 and 18:2-20:4 PtdCho and 1-3 h in 16:0-20:4, 18:1-20:4 PtdCho and PtdIns. The very short half-lives for arachidonate in the 16:1-20:4 and 18:2-20:4 PtdCho molecular species suggest important roles for these molecules in brain phospholipid metabolism and signal transduction.

Animals↗
PubMed1988

Fatty acid chain-shortening activity in the pulmonary type II cell.

Type II cells obtained from fetal rabbit lung tissue in culture were incubated with [14C]palmitic and [14C]stearic acids labeled at either the carboxyl or the terminal methyl groups. Significant chain shortening of [18-14C]stearic acid to radiolabeled palmitic acid was observed, with little chain shortening of palmitic acid to myristic acid. Incorporation of 14C into palmitic acid by beta-oxidation followed by de novo fatty acid biosynthesis was not detectable under the same experimental conditions. The palmitic acid supplied by chain shortening was preferentially incorporated into phosphatidylcholine instead of other lipids. Fatty acid chain-shortening activity in the type II cell appears to be capable of increasing the amount and relative proportion of palmitic acid available for phosphatidylcholine biosynthesis.

Animals↗
PubMed2001

Effect of 6 dietary fatty acids on the postprandial lipid profile, plasma fatty acids, lipoprotein lipase, and cholesterol ester transfer activities in healthy young men.

BACKGROUND: There is increasing evidence that postprandial triacylglycerol-rich lipoproteins may be related to atherogenic risk. OBJECTIVE: The objective was to investigate the effect of individual fatty acid intakes on postprandial plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acids, and preheparin lipoprotein lipase and cholesterol ester transfer protein (CETP) activities. DESIGN: Six test fats high (approximately 43% by wt) in stearic acid, palmitic acid, palmitic + myristic acid, oleic acid, elaidic acid (trans 18:1), and linoleic acid were produced by interesterification. After having fasted for 12 h, 16 healthy young men were served the individual test fats incorporated into meals (1 g fat/kg body wt) in random order on different days separated by washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after the meals. RESULTS: Different responses to the test-fat meals were observed for plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acid concentrations, and lipoprotein lipase and CETP activities (diet x time interaction: 0.001 < P < 0.05). Intake of the long-chain saturated fatty acids stearic and palmitic acids resulted in a relatively lower lipemic response than did intake of the unsaturated fatty acids, probably because the saturated fatty acids were absorbed less and at a lower rate; therefore, the lipemic response took longer to return to postabsorptive values. CONCLUSIONS: Fatty acid chain length and degree of saturation appear to affect the extent and duration of lipemia and affect hepatic output indirectly. These effects may not be mediated via effects on lipoprotein lipase and CETP activities.

Adult↗
PubMed1990

Effect of straight chain fatty acids on seizures induced by picrotoxin and pentylenetetrazole in mice.

The effects of straight chain fatty acids on seizures induced by picrotoxin and pentylenetetrazole were studied in mice. After i.p. injection capric, lauric, myristic, palmitic and stearic acid delayed the onset of picrotoxin-induced clonic convulsion in a dose-dependent manner. The survival time was also prolonged by the pretreatment with lauric, myristic, palmitic and stearic acid. However, the onset of the clonic convulsion induced by pentylenetetrazole was delayed only by lauric acid. The prolongation of the survival time was also observed only in the animals pretreated with capric and lauric acid. These results suggest that the straight chain fatty acids examined in the present study possess anticonvulsant activity in mice.

Animals↗
PubMed1992

The effects of glucose, insulin and metformin on the order parameters of isolated red cell membranes. An electron paramagnetic resonance spectroscopic study.

Human red blood cell (RBC) membranes (RBC ghosts) were treated with glucose, insulin and metformin. The order parameters of RBC membranes were determined by 5- and 16-doxyl-stearic acid spin labels. Metabolic effects were excluded using an isolated system of RBC membranes. The membranes were incubated with glucose in physiological (5 mM), renal threshold (10 mM) and manifested diabetic (20 mM) concentrations for limited times. High concentrations of glucose (10, 20, 100 mM) increase the order parameters of RBC membranes significantly. Insulin by itself has a similar effect which is, however, not strictly concentration-dependent. By contrast, metformin at therapeutic concentrations (0.5 and 5.0 microM) decreases the order parameters. At 50 microM concentration the metformin effect is expressed less and recurs at 100 microM concentration. The effects are significant with 5-doxyl-stearic acid, but are not significant with the 16-doxyl derivative. When RBC membranes are co-incubated with 20 mM glucose and metformin at 0.5 and 5.0 microM concentrations the order parameters as determined by 5-doxyl-stearic acid remain normal (= control values). Higher concentrations of metformin (50 and 100 microM) cause an overshoot to very low order parameters. Insulin at 10, 100 and 200 mU/L does not influence significantly the effects of metformin. Addition of physiological amounts of bovine serum albumin does not abolish the effects of metformin. Metformin, at therapeutic concentrations (0.5 and 5.0 microM), maintains the normal fluidity at the polar interface of isolated RBC membranes by counterbalancing non-enzymatic glycosylation with 20 mM glucose in vitro.

Cyclic N-Oxides↗
PubMed1981

[Extraction of fecal lipids and identification of hydroxystearic acid by gas chromatography-mass spectrometry (GC/MS)].

Fatty acids and hydroxy fatty acids in the intestine are of interest because of their cathartic properties. We describe a method for extraction of lipids from freeze dried homogenized stools and identification of the hydroxy stearic acid in the fecal lipids pattern by GC-MS. Recovery of 90-95 % shows the efficacy of extraction . Quantitative data of fecal hydroxy stearic acid excretion in some normal and chronic diarrhea affected children are reported.

Child↗