[Palmitic acid-stearic acid ratio with reference to the fatty tissue properties in the human species].
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Adipose Tissue↗
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Comparison of linoleic acid and stearic acid absorption by the gallbladder.
The absorption of [14C]linoleic acid and [14C]stearic acid in guinea pig bile by the in situ guinea pig gallbladder was compared. Linoleic acid was adsorbed at a faster rate than was stearic acid. Differences were also observed in the incorporation of these two fatty acids into complex lipids of the gallbladder mucosa. A greater portion of adsorbed linoleic acid was incorporated into triacylglycerol whereas a greater portion of stearic acid was incorporated into sphingomyelin. The significance of these findings in relation to the fatty acid composition of bile is discussed.
Animals↗
[The relationship between palmitic acid and stearic acid on the pharyngeal secretions of the newborn (author's transl)].
The authors report on their study of the ratio of palmitic acid to stearic acid (P/S) in the pharyngeal secretions of the newborn before the sixth hour of life. Four groups of infants were studied: 78 infants used as controls who hac no respiratory distress, 36 with hyaline membrane disease, 16 with transitory respiratory distress and 5 with perinatal asphyxia. The aetiological diagnosis of the respiratory distress was based on clinical as well as radiological and biological criteria. The P/S ratio is always less than 3 with hyaline membrane disease and above 3 in asphyxias. In the control group and the group with transitory respiratory distress the ratio ranged between 1.3 and 14 which was evidence of false negative results, probably attributable to treatment with cortisone given to the mother in premature labour in a certain number of cases. Study of the P/S ratio in amniotic fluid and in the pharyngeal secretions of 27 children born by Caesarean operation embodies a contradiction in the results the newborns in whom the ratio in the amniotic fluid was greater than 3 never had respiratory distress although the ratio studied at the same time in the pharyngeal secretions was low and sometimes less than 3.
Amniotic Fluid↗
Mouse brain uptake and metabolism of stearic acid.
After injection, labelled stearic acid is transported directly into the brain and incorporated into brain lipids without prior oxydation to acetate and resynthesis of fatty acids. Contamination by blood can be excluded. (The preparation contains all subcellular fraction except cytosol). The labelled stearic acid taken up is partly metabolized in the brain either by elongation or by degradation and in situ resynthesis of fatty acids. The activity in oleic acid and mono-unsaturated chains is hardly detectable. The labelled acids are incorporated into lipids or subcellular particles following characteristic kinetics, which show a diminution by 24 hours. When analysing the evolution of each lipid, it is shown that this profile is followed by phospholipids, but not by cerebrosides and free fatty acids. The formers are still increasing up to 50 hours, the latters are stable (suggesting a physical binding between membranes and free fatty acids). Thus nutrition is an important parameter for the synthesis of brain membranes as far as exogenous saturated fatty acids are needed.
Animals↗
Raman studies of the C-H and C-D stretching regions in stearic acid and some specifically deuterated derivatives.
Raman spectra of polycrystalline stearic acid-do, stearic acid-d35, 16:16-d2-18:18:18-d3-stearic acid, 18:18:18-d3-stearic acid, 17:17-d2-stearic acid, 17-d1-stearic acid, 16:16-d2-stearic acid, 12:12-d2-stearic acid and 12-d1-stearic acid have been obtained for the region containing the C-D and C-H stretching vibrations. Assignments of the methyl, methyl-d3, methylene, methylene-d2 and methylene-d1 stretching vibrations are discussed.
Deuterium↗
The binding isotherms for the interaction of 5-doxyl stearic acid with bovine and human albumin.
Binding isotherms for the interaction of 5-doxyl stearic acid with bovine and human albumin are reported. The critical micelle concentration (CMC) and the limiting solubility of 5-doxyl stearic acid were determined using the electron spin resonance (ESR)-spin label method. The CMC and the limiting solubility of this spin-label stearic acid in saline-phosphate buffer are 3.5 x 10(-5) M and 2 x 10(-4) M, respectively. We found no ESR line width evidence for pre-association of the spin-label stearate below the CMC. Maximum binding of the spin-label stearate to both bovine and human albumin occurs before micelle formation. The binding isotherm for spin-label stearic acid interaction with bovine albumin is in agreement with data obtained by others using [1-(14)C]stearic acid. For human albumin, comparison is difficult since previous data obtained with [1-(14)C]stearic acid vary widely. Comparison of the ESR 2T(||) values (the splitting between low and high field extremes, a measure of the degree of immobilization of protein-bound spin-label stearate) for bovine and human albumin indicates a greater immobilization of the spin-label molecules bound to human albumin. The binding data indicate that complexes are formed with bound spin-label stearate/albumin ratios of at least 18. The computed equilibrium constants for both bovine and human albumin indicate that the first seven spin-label molecules are tightly bound, log K > 5.0. The species predicted to form in solution by these equilibrium constants are reported.
Electron Spin Resonance Spectroscopy↗
Effect of petroselinic and stearic acids on the alkyl diacyl glycerides of Novikoff hepatoma cells.
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Carcinoma, Hepatocellular↗
Incorporation of stearic acid into brain lipids in the developing brain: blood-brain relationships during development.
The blood-brain relationship for stearic acid varies during development. Subcutaneously injected [1-14C]-stearic acid is taken up by brain. Age-related changes in the metabolism of stearic acid have been determined in mouse brain from birth to maturity. Total lipid radioactivity reaches a maximum at 18 days of age and decreases afterwards until adulthood. However, specific radioactivity presents the highest value at 1 day of age and declines from then on. At any age, the injected acid is taken up and partly metabolized in the brain, either by elongation or by degradation in situ and resynthesis of new fatty acids; it is also desaturated, and the oleic acid thus formed is eventually elongated. The labeled stearic acid is incorporated into brain lipids with a different pattern according to the age of the injected animal.
Age Factors↗
Model membrane studies of spin-label probes. Part 1. Mixed monolayers of 12-nitroxide stearic acid and myristic acid.
Pure and mixed monomolecular films of a cell membrane spin label probe, 12-nitroxide stearic acid have been studied where myristic acid was selected as the host lipid. The behavior of 12-nitroxide stearic acid at the air water interface is understood in terms of two molecular configurations: erect (with only the carboxyl group in the interface) and bent (with both the carboxyl group and the oxazolidine ring in the interface). In mixed films both of these conformations play a role at high surface pressures. At low probe concentrations, 12-nitroxide stearic acid is primarily in an erect conformation, while at high probe concentrations the reverse is true. This particular host lipid appears capable of erecting the probe molecule with only small concentrations of myristic acid. In a condensed host lipid, the probe is partially immiscible, and segregates to form a heterogeneous film from which it is readily collapsed. The probe is seen to perturb the molecular packing in this mixed system and the perturbation to be dependent on both the molecular shape and nature of the probe.
Binding Sites↗
In vivo incorporation of exogenous [1-14C]stearic acid into neurons and astrocytes.
Exogenous stearic acid is needed to synthesize the membranes of neurons and astrocytes. Subcutaneously injected [1-14C]acid is taken up through the 'blood brain barrier' and incorporated into lipids of both cell types, the specific radioactivity being higher in astrocytes as compared to neurons (2200 and 800 cpm/mg proteins, respectively), 20 h after injection. Phospholipids contain high amount of radioactivity (80% in astrocytes, 65% in neurons); glycosphingolipids contain low quantities of label in the two cell types. The injected acid is partly metabolized in the brain by elongation and desaturation (thus providing very long chains, saturated mono-unsaturated and poly-unsaturated); it is also partly degraded into acetate units (utilized for synthesis of palmitic acid).
Animals↗
[Study of the passage of stearic acid through blood-brain barrier and its incorporation in cerebral membranes (especially in myelin)].
Subcutaneously injected stearic acid is uptaken by brain and is further incorporated into membrane lipids (especially myelin). The uptake increases regularly up to 20 hrs. in total membranes as in myelin. In total membranes, there is a decrease between 20 and 24 hrs. followed by a recovery of the previous maximal activity. Moreover, the myelin activity increases up to 3 days, so far. Cerebrosides, isolated from both types of preparations, present an activity regularly increasing; but free fatty acids have a stable specific activity and a decreasing relative activity. The injected labelled stearic acid is directly incorporated into membrane lipids or is metabolized inside brain in longer chains (thus providing arachidic behenic and lignoceric acids) or in acetate units (utilized for synthesis of medium chain fatty acids such as palmitic acid).
Animals↗
The use of 8-anilino-1-naphthalenesulfonic acid as a reporter group molecule for circular dichroism and fluorescence measurements. The effect of stearic acid and sodium dodecylsulfate on the conformation of bovine and human serum albumin.
The fluorescence probe ANS(8-anilino-1-naphthalenesulfonic acid) was employed as a reporter group molecule for circular dichroism and fluorescence measurements in order to investigate the effects of stearic acid and sodium dodecylsulfate on the conformation of bovine and human serum albumin. Stearate as well as dodecylsulfate displaces ANS from the binding to both albumins. Besides this displacement, stearate and dodecylsulfate influence the fluorescence properties and the extrinsic Cotton effects on ANS bound to both albumins. It is suggested that the origin of these effects is a microdisorganization of the albumin structure, provoked by the binding of stearate and sodium dodecylsulfate. Each of the four extrinsic CD bands of bound ANS was influenced in a different manner by the addition of stearate and dodecylsulfate. Using the data of the fluorescence measurements and of the circular dichroism measurements it was possible to differentiate the effects of one ligand on both albumins and of both ligands on one albumin more efficiently than would have been possible using one of the two methods alone. It is suggested that the use of ANS as a reporter group molecule for fluorescence and circular dichroism measurements is a very good tool to detect small changes in the environment of ligand binding sites on protein molecules.
Anilino Naphthalenesulfonates↗
Identification of isomeric doxyl stearic acids by gas-liquid chromatography and mass spectrometry.
Direct probe and GC/MS spectra were determined for the isomeric 4- to 16-doxyl stearic acids and their methyl and silyl esters in pure form and in mixture with natural fatty acids and their esters. The base peak for all free and esterified doxyl stearic acids was at m/e 281. The methyl esters of all isomers gave nearly identical fragments in the high mass regions having M+ at m/e 398 with intensities of 2-3%. The isomers were identified on the basis of the fragments retaining the doxyl group, which had positive charge and were different for each compound. It was shown that the fragment m/e 281 may be used to identify and quantitate the stearate derivatives in presence of natural fatty acids. The silyl esters of the doxyl stearates gave complex mass spectra. The isomeric doxyl stearates were resolved by GLC on 3 ft. glass columns containing 1% SE-30 packing as methyl esters.
Electron Spin Resonance Spectroscopy↗
Oxidative desaturation of alpha-linoleic, linoleic, and stearic acids by human liver microsomes.
The desaturation of stearic, linoleic, and alpha-linolenic acids by human liver microsomes were studied. The microsomes were isolated from liver biopsies obtained during operation. It was shown that human liver microsomes are able to desaturate 1-14-C-alpha-linoleic acid to octadeca-6,9,12,15,-telraenoic acid: 1-15-C-linoleic acid to gammalinolenic acid; and 1-14-C-stearic acid to oleic acid in the same system described in the rat. However, the desaturation activity obtained was low compared to other mammals. This effect was attributed to fasting, pre-medication, or the anaesthesia.
Adult↗
Desaturation of stearic acid by liver and adipose tissue from obese-hyperglycaemic mice (ob/ob).
Stearic acid desaturase activity was assayed in preparations from perigenital adipose tissue and liver from lean and genetically obese female mice (ob/ob). The total activity in the perigenital adipose tissue from obese mice was threefold greater than in the tissue from lean mice, but per g of adipose tissue the activity was twofold greater in tissue from lean mice. In liver, the activity in obese mice was elevated at 8 weeks of age, remained elevated up to 24 weeks and then decreased by half at 48 weeks, but at all ages was higher than that in lean mice. The decrease in desaturase activity of liver from obese mice at 48 weeks corresponded to a change in the fatty acid composition of liver lipids toward that found in lean mice. Whereas in adipose tissue much of the increased enzyme activity may be due to tissue hyperplasia, in liver it is mainly an increased activity per cell.
Adipose Tissue↗
An ESR study of the anchoring of spin-labeled stearic acid in lecithin multilayers.
In egg lecithin-water lamellar phases, spin-labeled stearic acid gives two superimposed ESR spectra which are only well resolved when the temperature is greater than 30 degrees C. These two spectral components are attributed to the dissociated and non-dissociated forms of the fatty acid carboxylic group, anchored at two different positions in the polar interface constituted by the hydrated lipid polar heads. Results on such interactions of other functional groups (spin-labeled fatty ester and fatty alcohol) are also presented.
Binding Sites↗
12-(9-Anthroyl)stearic acid, a fluorescent probe for the ubiquinone region of the mitochondrial membrane.
1. 12-(9-Anthroyl)stearic acid can be incorporated into mitochondrial membranes. 2. The fluorescence properties of the membrane-bound probe are different from those of the free molecule. 3. The intensity of emission and fluorescence life-time of the probe is enhanced when, in the presence of substrate, the electron-transport chain is reduced. 4. This change in intensity has been demonstrated to be a result of collisional quenching by oxidised ubiquinone in the oxidised membrane but not when the respiratory chain is in the reduced state. 5. In pulsing anaerobic mitochondria with oxygen the rate of the fluorescence change is found to be slower than the rate of ubiquinone oxidation, suggesting that the probe detects a structural transition in the mitochondrial inner membrane. 6. This transition results in a constraint on ubiquinone motion in the reduced system. Model experiments, using lipid dispersions, have been carried out to test some of the interpretations.
Animals↗
beta-Oxidation of the coenzyme A esters of elaidic, oleic, and stearic acids and their full-cycle intermediates by rat heart mitochondria.
beta-Oxidation rates for the CoA esters of elaidic, oleic and stearic acids and their full-cycle beta-oxidation intermediates and for the carnitine esters of oleic and elaidic acids were compared over a wide range of substrate and albumin concentrations in rat heart mitochondria. The esters of elaidic acid were oxidized at about half the rate of the oleic acid esters, while stearoyl-CoA was oxidized equally as rapid as oleoyl-CoA. The full-cycle beta-oxidation intermediates of elaidoyl-CoA (trans-16 : 1 delta 7, -14 : 1 delta 5, and -12 : 1 delta 3) were found to be oxidized at rates nearly equal to those for the corresponding intermediates of oleoyl-CoA. Therefore, after the first cycle of beta-oxidation, oleoyl-CoA and elaidoyl-CoA are oxidized at nearly equal rates. The activity of fatty acyl-CoA dehydrogenase was higher with elaidoyl-CoA and its full-cycle intermediates as substrates than with the corresponding cisisomers. It was concluded that the slower oxidation rate of elaidic acid is not due to slower oxidation of any of its full-cycle beta-oxidation intermediates, nor to slower activity of fatty acyl-CoA dehydrogenase, nor to outer mitochondrial carnitine acyltransferase. Possible explanations to account for the slower oxidation rate of elaidic acid are discussed.
Acyl Coenzyme A↗