[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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Hydrogenation alternatives: effects of trans fatty acids and stearic acid versus linoleic acid on serum lipids and lipoproteins in humans.
The objective of this study was to compare the effects of linoleic acid (cis,cis-C18:2(n-6)) and its hydrogenation products elaidic (trans-C18:1(n-9)) and stearic acid (C18:0) on serum lipoprotein levels in humans. Twenty-six men and 30 women, all normolipemic and apparently healthy, completed the trial. Three experimental diets were supplied to every subject for 3 weeks each, in random order (multiple cross-over). The Linoleate-diet provided 12.0% of total energy intake as linoleic acid, 2.8% as stearic acid, and 0.1% as trans fatty acids. The Stearate-diet supplied 3.9 energy % as linoleic acid, 11.8% stearic acid, and 0.3% trans fatty acids. The Trans-diet provided 3.8 energy % as linoleic acid, 3.0% stearic acid, and 7.7% as monounsaturated trans fatty acids, largely elaidic acid (trans-C18:1(n-9)). Other nutrients were constant. Fasting blood was sampled at the end of each dietary period. Mean (+/- SD) serum LDL cholesterol was 109 +/- 24 mg/dl (2.83 +/- 0.63 mmol/l) on the Linoleate-diet. It rose to 116 +/- 27 mg/dl (3.00 +/- 0.71 mmol/l) on the Stearate-diet (change, 7 mg/dl or 0.17 mmol/l, P = 0.0008) and to 119 +/- 25 mg/dl (3.07 +/- 0.65 mmol/l) on the Trans-diet (change, 9 mg/dl or 0.24 mmol/l, P less than 0.0001). High density lipoprotein (HDL) cholesterol decreased by 2 mg/dl (0.06 mmol/l, P less than 0.0001) on the Stearate-diet and by 4 mg/dl (0.10 mmol/l, P less than 0.0001) on the Trans-diet, both relative to linoleic acid. Our findings show that 7.7% of energy (mean, 24 g/day) of trans fatty acids in the diet significantly lowered HDL cholesterol and raised LDL cholesterol relative to linoleic acid. Combination with earlier results (Mensink, R. P., and M. B. Katan. 1990. N. Engl. J. Med. 323: 439-445) suggests a linear dose-response relation. Replacement of linoleic acid by stearic acid also caused somewhat lower HDL cholesterol and higher LDL cholesterol levels. Hydrogenation of linoleic acid to either stearic or trans fatty acids produces fatty acids that may increase LDL and decrease HDL cholesterol relative to linoleic acid itself.
Adolescent↗
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↗
Metabolic effects of dietary stearic acid in mice: changes in the fatty acid composition of triglycerides and phospholipids in various tissues.
The fatty acid patterns of triglycerides and phospholipids extracted from adipose tissue, liver, heart, kidney, spleen, and lung of 3 groups of C57BL/6 mice were determined after feeding diets rich in palmitic acid (16:0) (high palmitic: 16:0 = 45.1% of total fatty acids), stearic acid (18:0) (high stearic: 18:0 = 42.9% of total fatty acids) and oleic acid (18:1) (high oleic: 18:1 = 79.7% of total fatty acids) for 9 months. Triglyceride content of adipose, liver, heart, kidney, lung and spleen tissues was significantly enriched in palmitic acid in mice fed the high palmitic diet (range among all tissues: 19.9% +/- 0.2% to 29.0% +/- 1.9% of total fatty acids) and in oleic acid in mice fed the high oleic diet (range 56.0% +/- 1.9% to 71.6% +/- 1.2%). The stearic acid content of organ triglycerides in mice fed the high stearic diet ranged from 3.7% +/- 0.3% to 10.8% +/- 1.2%; however, the content of oleic acid on this diet (range: 57.0% +/- 1.8% to 71.4% +/- 1.7%) was similar to the one observed in mice fed the high oleic diet. In all organs, phospholipids had a significantly higher percentage of stearic acid (range: 23.5% +/- 0.9% to 51.5% +/- 6.6%) than triglycerides, regardless of diet. To evaluate the production of oleate from stearate and palmitate, 2 groups of mice were fed the high palmitic and the high stearic diets for 1 week and then injected intravenously with [1-14C]palmitate and [1-14C]stearate and the amount of labelled oleate in liver triglycerides was measured.(ABSTRACT TRUNCATED AT 250 WORDS)
Adipose Tissue↗
What is the metabolic fate of dietary long-chain fatty acids (especially stearic acid) in normal physiological states, and how might this relate to thrombosis?
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Cholesterol↗
The metabolism of tetradecylthiopropionic acid, a 4-thia stearic acid, in the rat. In vivo and in vitro studies.
The metabolism of [1-14C]tetradecylthiopropionic acid (TTP), a 4-thia stearic acid, and its sulphoxide, [1-14C]texadecylsulphoxypropionic acid (TTP-SO), has been studied in intact rats, in isolated rat hepatocytes, and in rat liver mitochondria. Two pathways of oxidation (beta-oxidation and omega-oxidation) have been demonstrated. TTP is incorporated, in vivo, into tissue triacylglycerol and phospholipids, it is oxidized to CO2, and it is excreted in urine, mainly as carboxypropylsulphoxypropionic acid and a little as carboxymethylsulphoxypropionic acid. TTP-SO is metabolized, in vivo, more rapidly to the same two omega-oxidation products. In hepatocytes TTP is incorporated into triacylglycerol and phospholipids even more rapidly than stearic acid. It is recovered mainly in the 1-position of phosphatidylcholine. Some is oxidized to CO2 and acid-soluble products. TTP-SO is mainly omega-oxidized to the same metabolites as are found in urine. A small fraction is incorporated into phospholipids or oxidized to CO2. In isolated mitochondria [1-14C]TTP is converted into 14CO2, radioactive malonic semialdehyde, and addition products of malonic semialdehyde. In the presence of phenylhydrazine, malonic semialdehyde phenylhydrazone is the dominating product. In soluble extracts of mitochondria [1-14C]malonic semialdehyde is oxidized directly to 14CO2 in the presence of CoA and NAD+, probably by the (methyl)malonic acid semialdehyde dehydrogenase (EC 1.2.1.27).
Animals↗
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↗
Effects of stearic acid and beef tallow on iron utilization by the rat.
Two experiments were done in which anemic rats were fed diets containing safflower oil or stearic acid and low (10 ppm) or adequate (39-42 ppm) iron. Diets were 24% fat by weight. In the stearic acid diets, 2% (Experiment 1) or 4% (Experiment 2) of the fat was supplied by safflower oil to satisfy essential fatty acid requirements. Repletion of hemoglobin, hematocrit, and liver iron was assessed. Compared with safflower oil in both experiments, stearic acid had a significant positive effect (P less than 0.0001) on repletion of hemoglobin (Hb), hematocrit (Hct), and liver iron concentration; the effect on Hb and Hct was most pronounced when dietary iron was low. When expressed as g Hb/mg Fe intake, Hb repletion was affected by a significant interaction between fat and Fe (P less than 0.002) and was greatest in rats fed low iron stearic acid diets. In a third experiment, rats were fed low dietary iron and 24% safflower oil, 20% stearic acid + 4% safflower oil, 3.2% stearic acid + 20.8% safflower oil, or 20% beef tallow + 4% safflower oil. The 20% beef tallow provided 3.2% stearic acid in the total diet. The response of Hb and Hct were similar to those in the first two experiments for rats fed safflower oil or stearic acid. Rats fed beef tallow had significantly greater (P less than 0.05) Hb and Hct repletion than did rats fed safflower oil, although the degree of repletion was less than that observed in rats fed 20% stearic acid. There was no difference in iron repletion of rats fed 3.2% stearic acid and rats fed beef tallow. We conclude that stearic acid enhances iron utilization by rats.
Animals↗
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↗
Prognostic significance of tumor phosphatidylcholine stearic acid level in breast carcinoma.
The involvement of lipid enzymes in the action of oncogenes at the cell membrane level has suggested that membrane lipids could play a role in modulating the growth of tumors. We previously found that breast cancer patients with a low level of polyunsaturated fatty acids in their primary tumor's phosphatidylethanolamine had a high risk of early occurrence of visceral metastasis. In the present study, we prospectively examined whether fatty acid composition of tumor membrane phosphatidylcholine had a prognostic significance in a series of 63 patients with a localized presentation of breast cancer. Membrane phospholipids were extracted from the carcinoma tissue obtained at the time of surgery, phosphatidylcholine was purified, and its fatty acids were analyzed by capillary gas chromatography. During the follow-up period, 20 patients developed metastasis. In these patients, the proportion of stearic acid containing phosphatidylcholine was significantly lower than it was in the tumors of the 43 patients who remained metastasis-free. Multivariate analysis according to Cox showed that low stearic acid level in tumor phosphatidylcholine and high mitotic index were independently predictive of subsequent metastasis. The predictive value of stearic acid level on metastasis risk was higher in node-positive patients than in node-negative patients, allowing individualization of a subgroup of low stearic acid level, node-positive patients with very poor prognosis. We concluded that stearic acid level in tumor membrane phosphatidylcholine is an independent intra-tumor marker of breast cancer prognosis. This finding is new evidence that tumor's structural lipids are linked to the growth of breast cancer.
Adult↗
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↗
The metabolism of (1-14C) stearic acid in rat testicular tissue.
(1) The metabolism of stearic acid was studied in vivo following intratesticular injection of [1-14C] stearate. Soon after injection 14C activity was found mainly in the free fatty acid pool. This was followed at later time periods by transfer of label primarily to the phosphatide pool. During each time period significant amounts of label were recovered at 14CO2. (2) Analysis of 14C-labeled fatty acids from the injected testes demonstrated an initial rapid rate of oxidation and desaturation of [1-14C] stearate followed by a slower steady state rate. It was concluded that the initial rate was due to the rapid turnover of the highly labeled free fatty acid pool followed by a much slower rate as [14C] stearate was esterified to the more metabolically stable phospholipids. Elongation of the labeled stearic or its desaturated derivative was not observed. (3) The rate of desaturation in vitro of stearic acid was measured in microsomal preparations from rat testes and found to be 12.0 +/- 0.5 pmol/min/mg compared to the estimated in vivo value of 22 pmol/min/mg and the value of 390 pmol/min/mg for hepatic microsomal desaturase.
Animals↗
Incorporation into liver microsomal lipids of linoleic and stearic acids and of their respective products of delta 6 and delta 9 desaturation, gamma-linolenic and oleic acids: effect of age and of blackcurrant seed oil.
The incorporation of [1-14C]linoleic and [1-14C]stearic acid and of their delta 6 and delta 9 desaturation products (gamma-linolenic and oleic acids, respectively) into different classes of lipids was studied in liver microsomes of rats in function of the diet (blackcurrant seed oil diet, containing gamma-linolenic acid, versus control diet) and in function of age (3, 6 and 9 months). After delta 6 desaturation, total radioactivity was distributed between phospholipids, especially phosphatidylcholine, and neutral lipids. The desaturation product, gamma-linolenic acid, was totally recovered in the phospholipid fraction. Blackcurrant seed oil, which decreased the rate of delta 6 desaturation in 6- and 9-month-old rats, also decreased the incorporation of radioactivity in total phospholipids, especially in phosphatidylcholine. At 6 months of age, after delta 9 desaturation, the majority of radioactivity was recovered in neutral lipids principally as oleic acid, the desaturation product. The precursor, stearic acid, was highly incorporated into phospholipids, especially in rats on a diet of blackcurrant seed oil.
Aging↗