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At least 865 records · Page 48Linked to original sources
PubMed1977

Lipid metabolism of the yellow clam, Mesodesma mactroides: 3-saturated fatty acids and acetate metabolism.

The fate of labeled palmitate, stearate, and acetate administered to the yellow clam, Mesodesma mactroides, was investigated. 1(-14)C palmitic and 1(-14)C stearic acids were oxidized to CO2 to a limited extent. They were mainly incorporated in diacylglycerols and triacylglycerols and were converted to higher homologs. After administration, palmitic acid was converted to stearic and oleic acids, whereas administered stearic acid was converted to 18:1, 18:2, 20:1, and 20:2 acids. Labeled acetate was readily included by the clam in 12:0, 14:0, 14:1, 15:0, 16:1, 16:1, 16:2, 18:2, 18:1, 18:2, 20:1, 20:2, and 20:3 acids.

Acetates↗
PubMed1981

Effect of phagocytosis and ionophores on release and metabolism of arachidonic acid from human neutrophils.

Challenge of human neutrophils prelabeled with [3H] arachidonate and [14C] palmitate or [14C]-stearate with opsonized zymosan or the Ca2+ ionophores A23187 or Ionomycin caused the release of [3H], but not [14C], fatty acid. With the ionophores, but not zymosan, considerable conversion of the [3H] arachidonate to hydroxyeicosatetraenoates occurred. Although various isomers were recovered, the 5-hydroxyeicosatetraenoate appeared to be the major product. In these experiments, no [14C] products were detected such as lysophospholipid, diglyceride or monoglyceride. Although no definite statement can be made about the mechanism of release of arachidonate, our data are most easily interpreted as the result of the action of a phospholipase A2.

Anti-Bacterial Agents↗
PubMed1998

Long-chain fatty acid uptake by skeletal myocytes: a confocal laser scanning microscopy study.

Studies of regulation of free fatty acid (FFA) utilization by skeletal muscles have focused on plasma FFA delivery and on intracellular factors affecting FFA metabolism. The present study was conducted to directly analyse the uptake process of fatty acids into single myocytes. Cells were isolated from the rat flexor digitorum brevis muscle. Confocal laser scanning microscopy was utilized to analyse the uptake of the fluorescent fatty acid derivative 12-NBD-stearate, which is not metabolized by muscle tissue. Uptake represented a saturable function of the unbound fatty acid concentration in the medium (K(m) 366 +/- 118 nM, Vmax 2.1 +/- 0.3 AU/s) and depended on the medium sodium concentration. Reduced buffer pH increased initial uptake rates, whereas lactate (10 mM) had no effect. Membrane hyper- and depolarization decreased uptake rates. This study demonstrates for the first time kinetic data from isolated myocytes with evidence for a carrier-mediated transport mechanism for long-chain fatty acids.

4-Chloro-7-nitrobenzofurazan↗
PubMed2005

An infrared spectroscopic method for quantitative analysis of fatty alcohols and fatty acid esters in machinery oils.

A new infrared spectroscopic method suitable for determining total fatty alcohol and fatty acid ester concentrations in industrial oils has been developed. Oil samples were diluted with toluene (1:3 w/w), the toxicity and volatility of which are relatively low compared with more commonly used IR solvents, like carbon tetrachloride or carbon disulfide. Mixture standards were prepared from dodecanol, tetradecanol, octadecanol, methyl stearate and methyl palmitate. Some analytical and statistical tests were performed on the developed method. The recoveries and the repeatability of the method proved to be sufficient for the quantitative determination of fatty alcohol and fatty acid ester additives in industrial oils. Reproducibility testing in another laboratory also produced satisfactory results. The developed method also proved to be relatively quick and simple. This method was developed to satisfy industry's need to determine the concentrations of these oil additives, and it has already been applied successfully in machinery oil analysis.

Carbon Disulfide↗
PubMed1998

Prevention of intestinal adhesions after laparotomy in a rat model--a randomized prospective study.

We prospectively studied the effect of a foam composite containing glycerin, propylene glycol, polyol, stearine, stearate and silicone oil, which is known to form a temporary barrier layer when applied to epithelial surface, on adhesion prevention in rats. The small intestine abrasion model was used for creation of adhesions. Sixty male Sabra rats of a mean weight of 295 +/- 23 g were randomly assigned into four groups: group 1 (n = 20) underwent laparotomy and abrasion; group 2 (n = 20) underwent laparotomy, abrasion and intraperitoneal instillation of the foam composite; group 3 (n = 10) underwent laparotomy with abrasion and a second laparotomy with adhesiolysis 2 weeks later; and group 4 (n = 10), was treated in the same way as group 3 but during the second laparotomy the foam composite was instilled intraperitoneally. All animals were relaparotomized 2 weeks (groups 1 and 2) and 4 weeks (groups 3 and 4) after the initial laparotomy for adhesion scoring performed by a blinded independent investigator using the standard 0-3 adhesion grading score. Representative specimens of small intestine and liver from animals in groups 2 and 4 were analyzed. A significantly lower mean adhesion score was noted in group 2 (1.15 +/- 0.3) compared with that of group 1 (2.65 +/- 0.1) or group 3 (2.60 +/- 0.1) (P < 0.01). Group 4 had a significantly lower score (1.4 +/- 0.3) than group 3 or group 1 (P < 0.05). There was no significant difference in the mean adhesion score between groups 1 and 3. Histological examination revealed no evidence of residual foam composite or adverse reaction to its use in the intestine and liver. The foam composite tested may reduce the severity of intestinal adhesions after laparotomy and may also reduce the severity of recurrent adhesions after adhesiolysis. Intraperitoneal use of this composite is safe in rats. The exact mechanism of action is unclear but may be related to the formation of a temporary microlayer that coats the injured surface of the intestine and facilitates healing without adhesion formation. Further investigation is needed to evaluate its full potential.

Animals↗
PubMed1978

Intralysosomal hydrolysis of cholesterol esters of varying fatty acid composition in cultured human skin fibroblasts.

Intralysosomal accumulation of low density lipoprotein-cholesterol ester was achieved during incubation of cultured human skin fibroblasts in the presence of chloroquine and the subsequent hydrolysis of the cholesterol ester was studied after removal of chloroquine. The fall in the ratio of cholesterol linoleate to cholesterol oleate during recovery from chloroquine inhibition suggested preferential hydrolysis of cholesterol linoleate. To verify this assumption, low density lipoprotein (labeled with [3H] cholesterol linoleate, oleate, palmitate or stearate) was sequestered in the lysosomes as described above. The rate of hydrolysis of the different cholesterol esters was determined 24 and 48 h after removal of chloroquine from the medium and was found to be similar for the four cholesterol esters studied. These findings indicate that enrichment in cholesterol oleate in atheromatous lesions does not result from preferential hydrolysis of intralysosomal cholesterol linoleate, but rather could be due to preferential utilization of oleic acid for the esterification in the cytoplasm of free cholesterol released from the lysosomal compartment.

Cells, Cultured↗
PubMed1982

The relative deacylation of different molecular species of endogenous phosphatidylethanolamine in rat liver microsomes by phospholipase activity.

The relative deacylation of the 1-palmitoyl and 1-stearoyl homologues of different molecular species of endogenous phosphatidylethanolamine in rat liver microsomes via phospholipase activity was studied. For this purpose, the various molecular species of microsomal phosphatidylethanolamine were labelled specifically in the 1-position by incubation of rat liver microsomes with [14C]palmitoyl-CoA or [14C]stearoyl-CoA plus 2-acyl-sn-glycero-3-phosphorylethanolamine containing 18:1, 18:2, 20:4, 22:6, etc. followed by resuspension of the microsomal pellet. The loss of radioactivity from the total 1-[14C]palmitoyl and 1-[14C]stearoyl homologues of phosphatidylethanolamine amounted to 31 and 29%, respectively, when these microsomal preparations were incubated for 1 h in 50 mM Tris-HCl buffer (pH 8.5) containing 10 mM Ca2+. Regardless of whether palmitate or stearate resided in the 1-position, the susceptibility of the phosphatidylethanolamines to deacylation was not influenced significantly by the nature of the unsaturated fatty acid in the 2-position, as judged by selectivity indices for the relative disappearance of radioactivity from the individual classes (monoenoic, dienoic, trienoic, tetraenoic, pentaenoic and hexaenoic). A moderate discrimination against 1-stearoyl 2-saturated species was indicated. The findings indicate that fatty acid selectivity in the microsomal deacylation of phosphatidylethanolamine cannot account for the unique fatty acid and molecular species composition of this phospholipid in rat liver.

Animals↗
PubMed1990

The preparation and some physical properties of ten methyl dithiastearate isomers.

Ten methyl dithiastearate isomers, containing 0-4 methylene groups between the two sulfur atoms in each of the molecules, were synthesized using a one-pot synthesis approach. The preparation of the tetra-methylene (3,4), tri-methylene (5,6) and di-methylene (7,8) interrupted methyl dithiastearate isomers involved the asymmetric coupling of n-bromoalkanes, alkanedithiols and omega-bromoalkanoic acids. The mono-methylene interrupted isomers (9,10) were prepared from dibromethane, which was allowed to couple with n-alkanethiols and omega-mercaptoalkanoic acids. For the non-methylene interrupted isomers (11,12), n-alkanethiols were initially converted to the sulfenyl bromide and reacted with omega-mercaptoalkanoic acids. These sulfur-containing fatty ester analogues were found to be more polar and with longer retention times than methyl stearate when analyzed by TLC (silica) and GC (SE-30) respectively. In the 1H-NMR analysis the shifts of the protons of CH2 groups adjacent to the sulfur atoms in 3-6 appeared at 2.50-2.60 (t) delta, while the tri-methylene interrupted isomers (5,6) furnished an additional characteristic signal at 1.84 (quintet) delta arising from the protons of the beta-positioned CH2 between the sulfur atoms. Compounds 7-8 gave a singlet at 2.70 delta, while 9,10 also gave a singlet at 3.64-3.65 delta for the protons of the CH2 group situated between the sulfur atoms. In compounds 11,12 the shift of the protons of the CH2 adjacent to the sulfur atom appeared at 2.68 (t) delta.(ABSTRACT TRUNCATED AT 250 WORDS)

Chromatography, Gas↗
PubMed1994

Further studies on the adjuvanticity of stearyl tyrosine and amide analogues.

Stearly tyrosine has been described in the literature as a candidate adjuvant for human vaccines. More recently, other stearyl esters have been reported to be adjuvant-active. This preliminary study assesses the adjuvanticity of stearyl amides, including the amide analogue of stearyl tyrosine: tyrosyl stearylamine. This study indicates that phenylalanylethanolamine O-stearate induces a significant antibody response and a favourable isotype distribution.

Adjuvants, Immunologic↗
PubMed1984

Transfer of additives from plastics materials into foodstuffs and into food simulants--a comparison.

The transfer of stearyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate from high- and low-density polyethylenes and polypropylene as well as that of n-butyl stearate from high-impact polystyrene into several foodstuffs and into different food simulants under normal storage conditions was determined radioanalytically. Additionally, the transfer of these additives into the food simulants under the standard conditions usually requested by the authorities was determined. From these figures 'correction factors' were calculated, relating the amounts of additives transferred from the plastics materials into the foodstuffs under normal conditions of storage to the transfer of these additives from the test specimens into food simulants (e.g. olive oil and HB 307) under the standard test condition of exposure at 40 degrees C for 10 days.

Butylated Hydroxytoluene↗
PubMed1991

Ethanol-induced fatty acid ethyl ester formation in vivo and in vitro in rat lung.

Fatty acid ethyl esters (FAEE) are the end products of a non-oxidative pathway for ethanol metabolism in a variety of human, rabbit, rat and murine tissues. Our objective was to determine the significance of this pathway in the metabolism of ethanol by the rat lung. In vitro, 14C-labeled ethyl oleate formation was assayed in the lung and compared with the pancreas, liver, heart and brain. Lipids were extracted with acetone, and 14C-labeled ethyl oleate was isolated and quantified by thin layer chromatography (TLC) and scintillation spectrometry. FAEE synthetic activity in the lungs (in vitro) was found to be intermediate among the organs examined. In vivo, male rats received 10% ethanol in their drinking water with or without daily i.p. injections of 4-methylpyrazole (1 mmol/kg body wt) for 15 days. Another group of male rats received 4 g/kg body wt ethanol as a 50% (v/v) solution by gavage every 12 h for 2 days. FAEE from the three organs with the highest in vitro activity for FAEE synthesis (pancreas, liver and lung) were extracted with acetone, isolated from normal lipids by TLC and separated by gas chromatography. The lung had lower FAEE-forming activity than the pancreas or the liver in the 15-day studies. However, in the 2-day study, the lung had higher activity than the liver but lower activity than the pancreas. Ethyl oleate, ethyl stearate and ethyl palmitate were the predominant FAEE formed in the intact organism. Ethanol-induced FAEE may play a role in the development of alcohol-related injuries to the lung.

Animals↗
PubMed1995

Peroxisomal beta-oxidation activity and catalase activity during development and aging in mouse liver.

Liver peroxisomal beta-oxidation activity on stearate, oleate, linoleate and alpha-linolenate was investigated as a function of age in two mouse strains. Each fatty acid showed a similar beta-oxidation activity pattern with age characterized by a rapid increase (200%) from day 2 to 20 followed by a dramatic weaning-related decrease (70%) from day 20 to 22. There was a new increase (260%) from day 22 to 75, then a plateau up to day 300 days, and finally an age-related decrease (70%) from day 300 to 540. Oleic, linoleic and alpha-linolenic acids were respectively 5-, 7.5- and 9-fold more degraded than stearic acid. Catalase specific activity showed the same age-related pattern as fatty acid beta-oxidation. Both mouse strains showed the age-related decreases. The longer-lived strain exhibited higher activity for both peroxisomal beta-oxidation and catalase and the rate of decrease of these two activities during aging was the same for both strains. The catalase/alpha-linolenic acid beta-oxidation ratio was constant during adulthood and aging. These results suggest that peroxisomal beta-oxidation and catalase activities are closely related throughout and implications for long-chain and very long-chain fatty acid metabolism, maintenance of membrane fatty acid composition and anti-oxidant status during aging are discussed.

Age Factors↗
PubMed1995

The composition of individual molecular species of plasma phosphatidylcholine in human pregnancy.

The molecular species composition of plasma phosphatidylcholine (PC) was measured in sequential blood samples from 13 pregnant women from 16 weeks of gestation to delivery at term. The increased total plasma PC concentration at term was due solely to increased concentrations of individual species containing palmitate (16:0) rather than stearate (18:0) at the sn-1 position. The specific increase of PC16:0/22:6 concentration in mid-gestation suggests that adaptations to maternal hepatic PC metabolism may provide a mechanism to ensure adequate supply of 22:6(n-3) to the fetus. While cord plasma PC was comparable to liver PC composition from three stillborn term infants, the compositions of these tissues differed from maternal plasma PC, which contained significantly more PC16:0/18:2 and PC18:0/18:2. These results suggest that, although fetal acquisition of polyunsaturated fatty acids (PUFA) is dependent on the maternal lipid supply, the detailed composition of fetal plasma PC may be regulated largely by intrinsic fetal mechanisms such as placental and liver PC metabolism. Similarly, the specific alterations to maternal plasma PC composition in pregnancy, which we postulate are associated with the supply of PUFA to the fetus, were substantially independent of variations in maternal dietary lipid nutrition.

Chromatography, High Pressure Liquid↗
PubMed1991

Estradiol esters can replace 17 beta-estradiol in the stimulation of DNA and esterase synthesis by MCF-7 cells: a possible role for the estrogen-sensitive MCF-7 cell esterase.

In this communication we extend our earlier observations on estrogen-sensitive carboxyl esterases in MCF-7 human breast cancer cells able to hydrolyze esters of estradiol. Using either estradiol acetate or p-nitrophenyl hexanoate as substrates, esterase activity was found to increase 2-3-fold in MCF-7 cells maintained in the presence of 10(-8) M estradiol. Following sucrose density centrifugation, over 85% of total esterase activity was found in the cytoplasmic fraction. No esterase activity was found in spent media from growing cells. By size exclusion chromatography, estradiol acetate esterase activity exhibited a mol. wt of 45-50 kDa. Attempts to demonstrate incorporation of [3H]estradiol into estradiol fatty acid esters by the above MCF-7 cell line (203P) were unsuccessful, although, such incorporation could be demonstrated in two other MCF-7 cell sublines. Incubation of the 203P cells with 10 nM [3H]estradiol in the presence of 0.5 mM radioinert estradiol acetate resulted in the incorporation of 35 +/- 12% of the label into the estradiol acetate in 10 min. In the absence of radioinert estradiol acetate, no incorporation was observed. When MCF-7 cells were incubated with [3H]estradiol in the presence of a large excess of radioinert estradiol valerate, label was found only in estradiol valerate. Similarly, when the incubation was carried out in the presence of a mixture of radioinert estradiol acetate and valerate, label was incorporated into both esters. We conclude that the apparent formation of radiolabeled estradiol esters by MCF-7 cells incubated under the above conditions, results at least in part, from an esterase-catalyzed exchange reaction. Under conditions where no ester hydrolysis could be detected in the absence of cells, valerate and stearate esters of estradiol were found to be as effective as unesterified estradiol in stimulating esterase synthesis and the incorporation of [3H]thymidine into DNA. These results are consistent with a model in which an intracellular esterase in MCF-7 cells can generate estradiol from an exogenous lipoidal steroid and elicit an estrogen response.

Acetates↗
PubMed2005

Langmuir monolayer approaches to protein recognition through molecular imprinting.

Surface plasmon resonance (SPR) spectroscopy and atomic force microscopy (AFM) have been employed to investigate ferritin adsorption to binary surfactant monolayers of cationic dioctadecyldimethylammonium bromide (DOMA) and non-ionic methyl stearate (SME). Surfactant molar ratios, miscibility, and lateral mobility were controlled to define the number, size, and distribution of "binding sites" for ferritin, which under the low ionic strength conditions investigated, adsorbed to the monolayers predominantly through electrostatic interactions. Successive adsorption/desorption cycles revealed that fluid monolayers, capable of laterally restructuring during the initial protein adsorption event, bound up to 60% more ferritin (dependent on SME:DOMA ratios) as compared to monolayers that were immobilized on a hydrophobic support during this first adsorption step. The enhanced binding of ferritin to fluid monolayers was accentuated in films having non-ionic SME as the principal component. These findings support the premise that the surfactants reorganize to form favorable interactions with an adsorbing protein, leading to protein specific charge patterns, or templates, in the films. Template assessment, however, was complicated by the presence of an irreversibly bound protein fraction, which AFM revealed to be locally ordered protein clusters.

Adsorption↗
PubMed2003

Effects of Aroclor 1242 and different fish-based diets on vitamins A1 (retinol) and A2 (3,4-didehydroretinol), and their fatty acyl esters in mink plasma.

The effects of a 21-week exposure to Aroclor 1242 (1mg per day in feed) on plasma concentrations of vitamins A(1) (retinol) and A(2) (3,4-didehydroretinol) and their principal fatty acyl esters (A(1)-16:0, A(2)-16:0 (palmitates), A(1)-18:1n-9; A(2)-18:1n-9 (oleates), and A(1)-18:0; A(2)-18:0 (stearates)) were studied in young female mink (Mustela vison) fed a diet based on freshwater smelt. These vitamin levels were also examined in mink fed diets containing Baltic herring or fatty marine fish. In the Aroclor-exposed smelt-fed mink, the plasma concentrations of A(1) and A(2) esters were significantly lower than the levels in controls fed the uncontaminated smelt diet. In addition, the A(2) esters reacted more sensitively to the polychlorinated biphenyls than did A(1) esters. In contrast, in the plasma of the exposed mink the level of alcoholic A(1) was normal, and transport of thyroxine (T(4)) and nonspecific lipoprotein transport of major lipids were not impaired. Despite the large dietary supply of vitamin A(2) and high levels of plasma A(2) esters, the mink fed freshwater smelt had only trace amounts of alcoholic vitamin A(2) in their plasma. The concentrations of A(1) and A(2) esters in the plasma of all the mink studied correlated with the hepatic total concentrations of the vitamins. Thus, in carnivores that have nonspecific lipoprotein transport of vitamin A esters, determination of plasma levels of the esterified vitamins may be a useful nondestructive way to estimate stores of the vitamin A analogs in the body and to assess the organochlorine-induced decrease in the vitamin stores.

Administration, Oral↗
PubMed1989

Saturation of fat and cholecystokinin release: implications for pancreatic carcinogenesis.

In a study to determine the effect of saturation of fats on their ability to stimulate cholecystokinin (CCK) release six normal volunteers ate five test meals containing different fats with intervals of 1 week. Plasma CCK levels were measured by a specific radioimmunoassay and the gallbladder volume was calculated from ultrasound measurements. The sodium salt of the monounsaturated fatty acid oleic acid (3.5 g) produced a significantly greater integrated CCK response than that of the saturated fatty acid stearic acid (mean [SEM] 103 [41] vs 8[41] pmol.l-1.min). The gallbladder contracted to 42 (3)% of its initial volume after oleate but remained at 89 (8)% of its initial volume after stearate. Integrated CCK responses to dietary triglycerides (30 g) also differed significantly according to the degree of saturation--277 (58) pmol.l-1.min after corn oil (predominantly diunsaturated), 143 (14) pmol.l-1.min after olive oil (predominantly monounsaturated), and 44 (12) pmol.l-1.min after suet (predominantly saturated). The finding that unsaturated fats are stronger stimulants of CCK release than saturated fats may explain the promotion of pancreatic carcinogenesis in rats by unsaturated but not saturated fats and may support the role of CCK in this effect.

Adult↗
PubMed2003

Effect of hair care and hair cosmetics on the concentrations of fatty acid ethyl esters in hair as markers of chronically elevated alcohol consumption.

Fatty acid ethyl esters (FAEE) can be used as alcohol markers in hair. It was investigated in this study whether this diagnostic method is disturbed by hair care and hair cosmetics. Traces of ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate were detected in all of 49 frequently applied hair care products by headspace solid phase microextraction (HS-SPME) and gas chromatography-mass spectrometry (GC-MS). The highest concentration was 0.003% in a hair wax. From experiments with separated hair samples of alcoholics as well as from the evaluation of the FAEE concentrations and the data about hair care of 75 volunteers (alcoholics, social drinkers and teetotalers) follows that usual shampooing, permanent wave, dyeing, bleaching or shading are of minor importance as compared to the drinking amount and other individual features. However, false positive results were found after daily treatment with a hair lotion containing 62.5% ethanol, with a deodorant and with a hair spray. As an explanation, it is assumed that FAEE are formed in the sebum glands also after regular topical application of products with a higher ethanol content.

Alcohol Drinking↗