Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “STEARIC ACID”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,459 records · Page 81Linked to original sources
PubMed1977

Uptake and metabolism of fatty acids by soybean suspension cells.

Soybean suspension cultures very rapidly take up C16 and C18 fatty acids by a nonspecific, nonenzymic binding of exogeneously added fatty acids to cell walls and by a subsequent transfer into the cell where they are rapidly incorporated into triacylglycerols, phosphatidylcholines, and phosphatidylethanolamines. 14C-Palmitic and 14C-stearic acids follow this sequence but are not desaturated, wherease 14C-oleic and 14C-linoleic acids are transferred more rapidly than the saturated fatty acids and are then further modified. All the data fit a sequence of events by which free oleic acid is first activated to a CoA thioester, and then desaturated to linoleyl-CoA; both thioesters are then transferred to triacylglycerols, phosphatidylcholine, and phosphatidylethanolamine.

Acetates↗
PubMed2006

Dynamic behavior of fatty acid spin labels within a binding site of soybean lipoxygenase-1.

The putative substrate-binding site in lipoxygenases is long and internal. There is little direct evidence about how the unsaturated fatty acid substrates enter and move within the cavity to position themselves correctly for electron transfer reactions with the catalytic non-heme iron. An EPR spectroscopy approach, with spin-labeled fatty acids, is taken here to investigate dynamic behavior of fatty acids bound to soybean lipoxygenase-1. The probes are labeled on C5, C8, C10, C12, and C16 of stearic acid. The EPR-determined affinity for the enzyme increases as the length of the alkyl end of the probe increases, with a DeltaDeltaG of -190 cal/methylene. The probes in the series exhibit similar enhanced paramagnetic relaxation by the iron center. These results indicate that the members of the series have a common binding site. All of the bound probes undergo considerable local mobility. The stearate spin-labeled at C5 has the highest affinity for the lipoxygenase, and it is a competitive inhibitor, with a K(i) of 9 muM. Surprisingly, this stearate labeled near the carboxyl end undergoes more local motion than those labeled in the middle of the chain, when it is bound. This shows that the carboxyl end of the fatty-acid spin label is not rigidly docked on the protein. During catalysis, repositioning of the substrate carboxyl on the protein surface may be coupled to motion of portions of the chain undergoing reaction.

Catalytic Domain↗
PubMed1975

Distribution of newly formed palmitate and stearate among molecular species of choline and ethanolamine phosphatides.

The choline and ethanolamine phosphatides derived from isolated rat livers during perfusion with 75 percent deuterated water (Kuksis, A., Myher, J.J., Marai L., Yeung, S.K.F., Steiman, I. & Mookerjea, S. (1975) Can. J. Biochem. 53, 509-518) were resolved into molecular species by argentation thin-layer chromatography. The time course of percentage replacement of the newly synthesized fatty acids in each molecular species was determined by gas chromatography with mass spectrometry. The results confirmed the earlier postulated differential utilization of palmitic and stearic acids in glycerolipid biosynthesis as well as supported the hypothesis of a precursor-product relationship between the oligoenoic and tetranoic species of both phosphatides. Calculations of half-lives gave values of 14-19 h for palmitoyl oligoenes, 40-50 h for palmitoyl tetraenes, and 22-28 h for palmitoyl hexaenes of both choline and ethanolamine phosphatides. The corresponding stearoyl species had half-lives which ranged from 89 to 200 h. Evidence was obtained for a metabolic heterogeneity among subsets of molecular species recognized on the basis of combinations of new and old glycerol and fatty acids in the same glycerolipid molecule.

Animals↗
PubMed1985

Phospholipid (diacyl, alkylacyl, alkenylacyl) and fatty acyl chain composition in murine mastocytoma cells.

The phospholipids from murine mastocytoma FMA3 and P-815 clone cells were quantitatively analyzed, and the major glycerophospholipids were examined for their fatty acyl chain distribution. In these cells, the content of histamine was less than 1/100 of normal mouse mast cells, and FMA3 cells had 1.5-fold as much histamine content as P-815 cells. The predominant phospholipid species of both mastocytoma FMA3 and P-815 were choline-containing glycerophospholipids (48%) and ethanolamine-containing glycerophospholipids (29%). The remaining minor constituents were sphingomyelin (6%, 7%), phosphatidylinositol (7%, 5%), phosphatidylserine (2%, 5%), cardiolipin (4%, 3%), and phosphatidic acid (2%, 1% for FMA3 and P-815, respectively). The choline-containing glycerophospholipids consisted of high amounts of 1-O-alkyl-2-acyl type (31%, 25%) and 1,2-diacyl type (63%, 66%) and a smaller amount of 1-O-alk-1'-enyl-2-acyl type (7%, 8%). In contrast, ethanolamine-containing glycerophospholipids were characterized by high contents of 1-O-alk-1'-enyl-2-acyl type (36%, 31%) and 1,2-diacyl type (55%, 58%), and a lower level of 1-O-alkyl-2-acyl type (12% and 11% for FMA3 and P-815, respectively). Unlike choline-containing glycerophospholipids and sphingomyelin that were rich in palmitic acid, ethanolamine-containing glycerophospholipids, phosphatidylserine and phosphatidylinositol showed a high proportion of stearic acid in the overall fatty acid composition. The content of arachidonic acid was highest in phosphatidylinositol. Sphingomyelin had a large amount of long chain and polyunsaturated fatty acids. In both choline- and ethanolamine-containing glycerophospholipids, the predominant fatty acids in the sn-1-position were palmitic, stearic, and oleic acid.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗
PubMed1964

CELLULAR LIPIDS OF A NOCARDIA GROWN ON PROPANE AND N-BUTANE.

Lipid fractions of propane- and n-butane-grown nocardial cells each contain a chloroform-soluble, ether-insoluble polymer not observed previously in liquid n-alkane-grown cells. The polymer in propane-grown cells is poly-beta-hydroxybutyrate. The polymer in n-butane-grown cells apparently contains unsaturation in the molecule, and is identified tentatively as a co-polymer of beta-hydroxybutyric and beta-hydroxybutenoic (specifically 3-hydroxy 2-butenoic) acids. The other major component of the lipid fraction consists of triglycerides containing principally palmitic and stearic acids. There seems to be little qualitative distinction in the glycerides of propane- or n-butane-grown cells. Oxidative assimilation of n-butane is described.

Butanes↗
PubMed1991

Supplemental fatty acids alter lipid peroxidation and oxidant injury in endothelial cells.

The purpose of this study was to determine the effects of supplemental fatty acids on oxidant injury in cultured endothelial cells. Porcine pulmonary artery endothelial cells (PAEC) in monolayer culture were incubated in culture medium supplemented with 0.1 mM fatty acid or with fatty acid vehicle alone for 3 h. Monolayers were then exposed to oxidant stress (100 microM H2O2 in buffer) or to control conditions (buffer alone) for 30 min. Supplementation with stearic acid (18:0) or oleic acid [18:1(n-9)] reduced H2O2-induced PAEC injury measured as release of intracellular lactate dehydrogenase (LDH). In contrast, supplementation with linolenic acid [18:3(n-6)] or eicosatrienoic acid [20:3(n-3)] enhanced H2O2-induced injury to PAEC. Both supplemental cis-vaccenic acid [18:1(n-7)] and 18:1(n-9) reduced the production of lipid peroxidation products in oxidant-stressed PAEC, whereas supplementation with 18:3(n-6) enhanced lipid peroxidation. Supplementation with 18:1(n-9) protected PAEC from H2O2 as long as 72 h after supplementation despite the intracellular redistribution of [18:1(n-9)] from triglycerides to phospholipids. Saturated and monounsaturated supplemental fatty acids protected PAEC from oxidant injury, but polyunsaturated fatty acids enhanced oxidant injury. These results support the hypothesis that supplemental fatty acids replace resident fatty acids, alter the oxidant reactivity of the cellular lipids, and thereby modify the oxidant susceptibility of PAEC.

Animals↗
PubMed1984

Rumen fermentation in vitro as influenced by long chain fatty acids.

Responses of rumen microbes to fatty acids were evaluated by production of total volatile fatty acid and ratio of acetate to propionate. Fermentations were under carbon dioxide for 20 h in 50-ml Erlenmeyer flasks in a Dubnoff metabolic shaking incubator. Flasks contained 20 ml medium, 1 ml reducing solution, 750 mg substrate (450 mg hay plus 300 mg grain), and varying amounts of long-chain fatty acids supplied as free acids, as calcium salts, or as triglycerides. They were inoculated with 5 ml rumen fluid obtained from a cow fed 3.6 kg grass hay, 2.3 kg grain, and .2 kg tallow daily. Volatile fatty acid production was decreased by long-chain fatty acids that contained less than 18 carbon atoms and by unsaturated long-chain fatty acids with 18 carbon atoms. Lauric acid decreased volatile fatty acid production by 69% and induced unusual acetate/propionate ratio (40:1). Stearic acid, however, did not affect volatile fatty acid production or acetate/propionate ratio. Within two series of long chain fatty acids (myristic, palmitic, stearic, arachidic; stearic, oleic, linolenic), melting point accounted for 93 to 95% of the variation of volatile fatty acid production and acetate/propionate. As calcium salts, long chain fatty acids caused small changes of fermentation. Our data support the proposition that hard fats and calcium salts of long-chain fatty acids do not interfere with ruminal fermentation.

Acetates↗
PubMed1989

Mitochondrial and peroxisomal beta-oxidation of stearic and lignoceric acids by rat brain.

Crude subcellular fractions were prepared from adult rat brains by differential centrifugation of brain homogenates. Greater than 98% of the cellular mitochondrial marker enzyme activity sedimented in the heavy and light mitochondrial pellets, and less than 1% of the activity sedimented in microsomal pellets. Lysosomal marker enzyme activities mainly (71-78% of cellular activity) sedimented in the heavy and light mitochondrial pellets. Significant amounts of the lysosomal marker enzyme activity also sedimented in the crude microsomal pellets (9-13% of total) and high-speed supernatants (14-16% of total). The specific activities of microsomal and peroxisomal marker enzyme activities were highest in the crude microsomal pellets. Fractionation of the crude microsomal pellets on Nycodenz gradients resulted in the separation of the bulk of the remaining mitochondrial, lysosomal, and microsomal enzyme activities from peroxisomes. Fatty acyl-CoA synthetase activities separated on Nycodenz gradients as two distinct peaks, and the minor peak of the activities was in the peroxisomal enriched fraction. Fatty acid beta-oxidation activities also separated as two distinct peaks, and the activities were highest in the peroxisomal enriched fractions. Mitochondria were purified from the heavy mitochondrial pellets by Percoll density gradients. Fatty acyl-CoA synthetase and fatty acid beta-oxidation activities were present in both the purified mitochondrial and peroxisomal enriched fractions. Stearoyl-CoA synthetase activities were severalfold greater compared to lignoceroyl-CoA synthetase, and stearic acid beta-oxidation was severalfold greater compared to lignoceric acid beta-oxidation in purified mitochondrial and peroxisomal enriched fractions.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Studies on the superoxide releasing site in plasma membranes of neutrophils with ESR spin-labels.

Superoxide (O2-)-generating membranes of pig blood neutrophils were studied by the ESR spin-label method. Neutrophils were spin-labeled with doxylstearic acids, consisting of nitroxide free radicals bonded to the 5, 7, 12, or 16 position of stearic acid (5-, 7-, 12-, or 16-DS), to detect the reduction of their nitroxide radicals at different positions in the membrane. The spin-labeled cells were then stimulated with phorbol myristate acetate (PMA). Stimulation of the labeled cells resulted in a marked decrease in the spin concentration of 5-DS due to the reduction by O2-, but not in those of the other three DS labels. This reduction of 5-DS was completely inhibited by copper salicylate (CS), a hydrophobic and permeable O2(-)-scavenger, but not by superoxide dismutase (SOD). CS was not inhibitory on the respiratory burst, i.e., O2(-)-generating activity of neutrophils. On the contrary, if the spin-labels were present in the extracellular medium, SOD inhibited the reduction of all four DS labels due to O2- released from PMA-stimulated cells. These results suggest that the O2(-)-releasing site is not located at the outer surface of the plasma membrane but in an inner hydrophobic environment a short distance (around 4-5 A) from its outer surface.

Animals↗
PubMed1995

Age-related changes in the percentage of oleate in adipose tissue of male and female Fischer rats.

Fischer 344 rats showed sex difference in the percentage of oleate in lipids of the omental adipose tissue (Thorling, E.B. and Overvad, K. (1994) Nutr. Res. 14, 569-576). The development of this difference was studied with respect to time in rats maintained on laboratory chow, from the age of 3 weeks to 20 weeks. From the age of 3 weeks to 5 weeks the percentage of oleate increased slightly in both sexes. From the age of 5 weeks to 13 weeks the percentage (mean +/- S.D., n = 5) increased further in the female rats from 24.8 +/- 0.6% to 27.6 +/- 0.6%, whereas in the male rats it dropped from 22.9 +/- 0.4% to 20.2 +/- 0.6% at the same time points, respectively. In adult rats, age 20 weeks, the percentage of oleate was 28.6 +/- 0.3% and 19.6 +/- 0.5% for females and males, respectively. Castrated males partly maintained their juvenile level, being 21.1 +/- 1.1% fourteen weeks after castration at the age of 6 weeks. Oestrogen injections twice a week to the castrated rats increased their oleate percentage within the same period to 23.4 +/- 0.3%, partly reflecting the increase observed in the female rats. Stearic acid showed similar but less pronounced changes. The ratio oleic acid/stearic acid was constantly higher in the female than in the male rats, and this difference increased with age. The results of the present study suggest that these changes in percentage of oleate in adipose tissue lipids may partly have been caused by an effect of sex steroids on the delta-9-desaturase.

Adipose Tissue↗
PubMed2006

Differential effect of saturated, monounsaturated, and polyunsaturated fatty acids on alloxan-induced diabetes mellitus.

Earlier, we reported that oils rich in omega-3 eicosapentaenoic acid and docosahexaenoic acid and omega-6 gamma-linolenic acid and arachidonic acid prevented the development of alloxan-induced diabetes mellitus in experimental animals. Here we report the results of our studies with pure saturated stearic acid (SA), monounsaturated oleic acid (OA) and omega-6 arachidonic acid (AA) on alloxan-induced diabetes mellitus in Wistar male rats. Prior oral supplementation with AA prevented alloxan-induced diabetes mellitus, whereas both SA and OA were ineffective. Cyclo-oxygenase (COX) and lipoxygenase (LO) inhibitors did not block this protective action of AA against alloxan-induced diabetes, suggesting that both prostaglandins and leukotrienes are not involved, and that AA by itself is effective. Furthermore, AA restored the anti-oxidant status to normal range in various tissues. These results suggest that AA protects pancreatic beta cells against alloxan-induced diabetes in experimental animals by attenuating oxidant stress.

Alloxan↗
PubMed2000

Lipid chain dynamics in stratum corneum studied by spin label electron paramagnetic resonance.

The lipid chain motions in stratum corneum (SC) membranes have been studied through electron paramagnetic resonance (EPR) spectroscopy of stearic acid spin-labeled at the 5th, 12th and 16th carbon atom positions of the acyl chain. Lipids have been extracted from SC with a series of chloroform/methanol mixtures, in order to compare the molecular dynamics and the thermotropic behavior in intact SC, lipid-depleted SC (containing covalently bound lipids of the corneocyte envelope) and dispersion of extracted SC lipids. The segmental motion of 5- and 12-doxylstearic acid (5- and 12-DSA) and the rotational correlation time of 16-doxylstearic acid (16-DSA) showed that the envelope lipids are more rigid and the extracted lipids are more fluid than the lipids of the intact SC over the range of temperature measured. The lower fluidity observed for the corneocyte envelope, that may be caused mainly due to lipid-protein interactions, suggests a major contribution of this lipid domain to the barrier function of SC. Changes in the activation energy for reorientational diffusion of the 16-DSA spin label showed apparent phase transitions around 54 degrees C, for the three SC samples. Some lipid reorganization may occur in SC above 54 degrees C, in agreement with results reported from studies with several other techniques. This reorganization is sensitive to the presence of the extractable intercellular lipids, being different in the lipid-depleted sample as compared to native SC and lipid dispersion. The results contribute to the understanding of alkyl chain packing and mobility in the SC membranes, which are involved in the mechanisms that control the permeability of different compounds through skin, suggesting an important involvement of the envelope in the skin barrier.

Animals↗
PubMed1992

Controlled antibody delivery systems.

We have developed methods for controlling the release of antibodies (Ab) from biocompatible polymers. Human Ab, human Ab fragments, and mouse monoclonal antibody (mAb) directed against human chorionic gonadotropin (anti-hCG) were incorporated into matrices of poly(ethylene-co-vinyl acetate), which is stable in biological environments. Human Ab and bovine gamma-globulin were also incorporated in biodegradable matrices of a poly-anhydride copolymer composed of a stearic acid dimer and sebacic acid. Abs were slowly released from all the polymeric carriers during 30 days of continuous immersion in buffered saline. The ability of anti-hCG to bind antigen was retained following release from EVAc matrices. Only minor Ab aggregation was observed following release from either polymer. Polymeric delivery systems, similar to those described here, may become an important element in the delivery of mAbs to humans for immunoprotection against infectious diseases or the delivery of mAb-conjugates for immunotherapy against cancer.

Anhydrides↗
PubMed1980

[Evaluation of P/S ratio and surface-tension measurements in amniotic fluid for prediction of pulmonary fetal maturity (author's transl)].

For the prediction of fetal lung maturity the palmitin stearic acid quotient (P/S ratio) was obtained by amniocentesis from 83 amniotic fluid samples of normal pregnancies, between the 28th and 40th week of pregnancy. This ratio was compared with the surface characteristics of the amniotic fluid in the Wilhelmy balance. A significant correlation was established between these two methods (correlation ellipsis r = 0.82, p < 0.01). The P/S ratio curve showed a marked increase during the 32nd and 36th week of pregnancy, indicating lung maturity. The P/S > 3 value usually reached during the 35th week of pregnancy indicates lung maturity. During the same time amniotic fluid samples were also obtained by amniocentesis from 37 complicated pregnancies. The surface tension as well as the P/S ratio were compared with the already established normal curves. A deceleration was found in cases of rhesusincompatibility and diabetes mellitus. In patients with EPH-gestosis and placental insufficiency only a slight acceleration towards the end of pregnancy was observed. Statistical proof of these trends was not feasible due to the limited number of patients in each group. Comparing the two methods regarding the predictability of pulmonary function in infants, the P/S ratio showed a larger number of false positive findings than the surface tension measurement method. Both methods produced an equal number of false negatives. Optimum results can be obtained by combining P/S ratio and surface tension measurements. This procedure is prognostically accurate in more than 96% of all cases.

Amniotic Fluid↗
PubMed1988

Dietary fat in relation to fatty acid composition of red cells and adipose tissue in colorectal cancer.

Fatty acids were determined in erthrocytes in 49 patients with colorectal cancer and compared with age and sex-matched controls. Marginally increased levels of stearic acid (P = 0.057) and oleic acid (P = 0.064) and decreased arachidonic acid (P = 0.043) occurred in cancer patients. There was no difference in the stearic to oleic acid ratio between the two groups. Dietary intake, assessed by dietary recall and adipose tissue analysis was also not different. In control subjects the polyunsaturated:saturated (P:S) fatty acid ratio correlated between diet and adipose tissue (P less than 0.01, at least). In contrast cancer patients showed different correlations; in particular dietary and erythrocyte P:S fatty acid ratios correlated (P less than 0.01). These findings may indicate disturbed fat metabolism in cancer patients. The erythrocyte stearic to oleic acid ratio is of no diagnostic value.

Adenocarcinoma↗
PubMed2002

Immobilization of urease on poly(N-vinyl carbazole)/stearic acid Langmuir-Blodgett films for application to urea biosensor.

Urease was immobilized in mixed monolayers of poly(N-vinyl carbazole) (PNVK) and stearic acid (SA) formed at an air-water interface. The monolayers were transferred onto indium-tin-oxide (ITO) coated glass plates using Langmuir-Blodgett (LB) film deposition technique. Urease immobilized on PNVK/SA LB films, characterized using FTIR and UV-visible spectroscopy, was found to exhibit increased stability over a wide pH (6.5-8.5) and temperature (25-50 degrees C) range. Potentiometric measurements on these urease electrodes were carried out using an ammonium ion analyzer. Two values for K(m)(app) were obtained at lower and higher concentrations of substrate urea.

Biosensing Techniques↗