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PubMed1996

Pilot study on plasma fatty acids in poorly controlled non insulin dependent diabetic Melanesians.

Different data have been reported with respect to the distribution of plasma and tissue fatty acids in patients with diabetes mellitus and some studies have suggested that severe diabetes is required to produce the fatty acid abnormalities observed in the diabetic rat. We studied the plasma fatty acid profile with particular attention to the omega 3 and 6 fatty acids in 14 non insulin dependent (NIDDM) diabetic Melanesians, majority of whom were poorly controlled (mean glycosylated haemoglobin levels of 12.8%), their mean age was 43.0 +/- 6.3 with disease duration of 5.2 +/- 4.8 years. Plasma fatty acids were estimated by gas chromatography (GC) using a flame ionisation detector (FID). Each diabetic was age and sex matched with a non diabetic, healthy control. Though the plasma concentrations of arachidonic (20:4, omega-6), eicosapentanoic (20:5 omega-3) and docosahaxaenoic (22:6 omega-3) acids were lower than in control subjects, these values were of no significant difference. Similarly, no significant differences were observed between the total plasma saturated fatty acids (palmitic and stearic acids) of diabetic and control subjects. The results of this pilot study suggest that poor metabolic control may not be associated with plasma fatty acid abnormalities in NIDDM patients.

Adult↗
PubMed1996

A pilot study on plasma fatty acids in poorly controlled non insulin dependent (type 2) Melanesian diabetics.

Different data have been reported with respect to the distribution of plasma and tissue fatty acids in patients with Diabetes mellitus and some studies have suggested that severe diabetes is required to produce the fatty acid abnormalities observed in the diabetic rat. We studied the plasma fatty acid profile with particular attention to the omega three and six fatty acids in 14 non insulin dependent (NIDDM) Melanesian diabetics the majority of whom were poorly controlled (mean glycosylated haemoglobin levels of 12.89pc), their mean ages were 43.0 + 6.3 with a duration of 5.2 + 4.8 years. Plasma fatty acids were estimated by gas chromatography (GC) using a flame ionization detector (FID). Each diabetic was age and sex matched with a non diabetic healthy control. Through the plasma concentrations of arachidonic (20:4, w-6), eicosapentanoic (20:5, w-3) and docosahaxaenoic (22:6, w-3) acids were lower than in control subjects, these values were of no significant difference. Similarly, no significant differences were observed between the total plasma saturated fatty acids (palmitic and stearic acids) of diabetic and control subjects. The results of this pilot study suggest that poor metabolic control may not be associated with plasma fatty acids abnormalities in NIDDM patients.

Adult↗
PubMed1978

Spin-label study of the relation between enzymatic activity and lipid-protein organization in reconstituted cytochrome c oxidase.

Lipid-depleted cytochrome c oxidase (EC 1.9.3.1) containing less than 20 microgram lipids per milligram protein was reconstituted with pure phospholipids of well-defined chemical structure and fatty acid composition without using detergents and (or) sonication. For the maximal restoration of electron transport activity, lipid-depleted cytochrome c oxidase required acidic phospholipds such as phosphatidylglycerol or phosphatidylserine or lysophospholipids such as lysophosphatidylcholine or lysophosphatidic acid, but no specific phospholipid fatty acid composition was necessary. The organization of the lipid environment of the reconstituted cytochrome c oxidase, having a well-defined lipid composition, morphology, and a high specific activity, was examined by electron spin resonance spectroscopy using 2-(14-carboxytetradecyl)-2-ethyl-4,4-dimethyl-3-oxazolidinyloxyl (16-doxyl stearic acid) and 16-doxyl stearic acid - containing phosphatidylglycerol. The presence of boundary lipid was established in both lamellar and micellar organizations of reconstituted cytochrome c oxidase and was not necessarily related to the enzymatic activity of the complex. Our results have established that aside from structural considerations, the boundary lipid, at least in the reconstituted cytochrome c oxidase, is a necessary but not sufficient condition for the enzymatic expression of cytochrome c oxidase.

Animals↗
PubMed1989

Influence of glycolipid oligosaccharide and long-chain base composition on the thermotropic properties of dipalmitoylphosphatidylcholine large unilamellar vesicles containing gangliosides.

The thermotropic behavior of dipalmitoylphosphatidylcholine large unilamellar vesicles containing gangliosides has been studied by high-sensitivity heating and cooling differential scanning calorimetry. These studies have been directed to identify and evaluate the influence of both the ganglioside lipidic portion and oligosaccharide moiety on the physical properties of phospholipid bilayers containing gangliosides. The influence of the ganglioside lipidic portion has been evaluated by studying the behavior of vesicles containing different GD1a molecular species carrying homogeneous lipid moieties (C20 or C18 sphingosine or sphinganine and stearic acid). The influence of the ganglioside saccharide portion was evaluated by investigating the thermotropic behavior of vesicles containing different gangliosides (GM1, Fuc-GM1, GD1a, GT1b) carrying the same homogeneous long-chain base moiety (C20 sphingosine and stearic acid). These studies, in conjunction with previous studies using homogeneous lipidic portion ganglioside GM1 and phosphatidylcholines of various chain lengths [Masserini, M., & Freire, E. (1986) Biochemistry 25, 1043-1049], indicate that, for a given oligosaccharide composition, gangliosides exhibit lateral phase separation in an extent dependent upon the length and unsaturation difference between the ganglioside long-chain base and phosphatidylcholine acyl chains. For a given ganglioside lipidic composition the extent of phase separation is dependent upon the number of sugar units present in the glycolipid. The addition of Ca2+ induces or enhances phase separation in a manner dependent on the long-chain base and oligosaccharide composition. Cooling differential scanning calorimetry experiments showed that the ganglioside property to form aggregates within the membrane is independent of the initial physical state of the bilayer.(ABSTRACT TRUNCATED AT 250 WORDS)

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

Transport of heptafluorostearate across model membranes. Membrane transport of long-chain fatty acid anions I.

Heptafluorostearic acid, an isogeometric derivative of stearic acid, has a pK(a) value of about 0.5. To evaluate the suitability of heptafluorostearate as model compound for anions of long-chain fatty acids in membrane transport, monolayer and liposome studies were performed with lipid mixtures containing phospholipids;-cholesterol-heptafluorostearate or stearate (100:40:20 molar ratios). Transfer of heptafluorostearate and stearate from liposomes to bovine serum albumin (BSA) was followed by measuring the intrinsic fluorescence of BSA. The percentage of heptafluorostearate, equivalent to the amount placed in their outer monolayer, transferred from liposomes (120;-130 nm diameter) to BSA was 55.7 +/- 3.7% within 10 min at 25 degrees C and 55 +/- 2% within 5 min at 37 degrees C. Slow transfer of 22.7 +/- 2.5% of heptafluorostearate at 25 degrees C followed with a half-life of 2.3 +/- 0.4 h and of 20 +/- 4% at 37 degrees C with a half-life of 0.9 +/- 0.1 h until the final equilibrium distributions between BSA and liposomes were reached, 79 +/- 6% to 21 +/- 5% at 25 degrees C and 75 +/- 5% to 25 +/- 4% at 37 degrees C. The pseudounimolecular rate constants for flip-flop of heptafluorostearate equal k(FF,25) = 0.24 +/- 0.05 h(-) and k(FF,37) = 0.6 +/- 0.1 h(-), respectively. By comparison, transfer of stearate required only 3 min to reach equilibrium distribution. The difference between heptafluorostearate and stearate may be explained by a rapid flip-flop movement of the un-ionized fatty acids which exist in different concentrations in accordance with their pK(a) values. Half-life of flip-flop of heptafluorostearate makes it suitable to study mediated membrane transport of long-chain fatty acid anions.

Animals↗
PubMed1976

Anthroyl stearate as a fluorescent probe of chloroplast membranes.

1. A reversible light-induced enhancement of the fluorescence of a "hydrophobic fluorophore", 12-(9-anthroyl)-stearic acid (anthroyl stearate), is observed with chloroplasts supporting phenazine methosulfate, cyclic or 1,1'-ethylene-2,2'-dipyridylium dibromide (Diquat) pseudo-cyclic electron flow; no fluorescence change is observed when methyl viologen or ferricyanide are used as electron acceptors. The stearic acid moiety of anthroyl stearate is important for its localization and fluorescence response in the thylakoid membrane, since structural analogs of anthroyl stearate lacking this group do not show the same response. 2. This effect is decreased under phosphorylating conditions (presence of ADP, Pi, Mg2+), and completely inhibited by the uncoupler of phosphorylation NH4Cl(5-10mM), as well as the ionophores nigericin and gramicidin-D (both at 5 - 10(-8)M). The MgCl2 concentration dependence of the anthroyl stearate enhancement effect is identical to that previously observed for cyclic photophosphorylation, as well as for the formation of a "high energy intermediate". The anthroyl stearate fluorescence enhancement is inhibited by increasing concentrations of ionophores in parallel with the decrease in ATP synthesis, but is essentially unaffected by specific inhibitors (Dio-9 and phlorizin) of photophosphorylation; thus, it appears that anthroyl stearate monitors a component of the "high energy state" of the thylakoid membrane rather than a terminal phosphorylation step. 3. The light-induced anthroyl stearate fluorescence enhancement is suggested to monitor a proton gradient in the energized chloroplast because (a) similar enhancement can be produced by sudden injection of hydrogen ions in a solution of anthroyl stearate; (b) when the proton gradient is dissipated by gramicidin or nigericin light-induced anthroyl stearate fllorescence is eliminated; (c) when the proton gradient is dissipated by tetraphenylboron, light-induced anthroyl stearate fluorescence decreases, and (d) light-induced anthroyl stearate fluorescence change as a function of pH is qualitatively similar to that observed with other probes for a proton gradient (e.g. 9-aminoacridine). Furthermore, anthroyl stearate does not monitor H+ uptake per se because (a) the pH dependence of H+ transport is different from that of the anthroyl stearate fluorescence change, and (b) tetraphenylboron, which does not inhibit H+ uptake, reduces anthroyl stearate fluorescence. Thus, anthroyl stearate appears to be a useful probe of a proton gradient supported by phenazine methosulfate of Diquat catalyzed electron flow and is the first "non-amine" fluorescence probe utilized for this purpose in chloroplasts.

Anthracenes↗
PubMed2004

Compositional and moisture content effects on the biodegradability of zein/ethylcellulose films.

The effect of moisture content and film composition on biodegradability is the focus of this study. Flexible films were first characterized for the effect on water sorption isotherms of relative humidity, temperature, zein content, and the addition of the plasticizers stearic acid, poly(ethylene glycol), or etoxylated ricine oil. Zein/ethylcellulose (EC) mixture films had a behavior between that for pure zein and EC films, which had the lowest water sorption. For films with plasticizer, the lowest water sorption at 25 degrees C was observed for those with stearic acid. Biodegradability of zein/EC films, evaluated using bacterial cultures selected for their zein proteolytic activity and isolated from a local solid waste landfill and a lagoon, showed no plasticizer effect even though its effect on moisture content was significant. Large differences were observed at different film zein concentration with the highest biodegradability for 100% zein. However, biodegradability did not mimic the water sorption behavior of zein/EC mixture films.

Biodegradation, Environmental↗
PubMedDate not supplied

[Cerebrosides and sulfocerebrosides in the brain of the macaque Macaca fascicularis].

The content of cerebrosides and sulfocerebrosides has been determined in the whole brain, in the gray and white matter of the cerebral hemispheres of the macaque. Fatty acid composition and long chain bases of these sphingolipids in the whole brain were also investigated. The species studied belongs to the order of higher primates, the family of lower Old World monkeys. In the whole brain, rather high content of both sphingolipids was found, the cerebral white matter being the richer. Cerebrosides with hydroxy acids predominate in the whole brain, in the white and gray matter. Cerebrosides of the whole brain contain mainly palmitic and stearic acids and relatively small amounts of C24 normal fatty acids. In sulfocerebrosides, the proportion of palmitic and stearic acids is lower and that of C24 normal fatty acids--larger, as compared to cerebrosides. In both sphingolipids, the content of saturated hydroxy acids, mainly cerebronic acid, is rather high. Among the long chain bases, only sphingenine and sphinganine were detected the former being predominant. Sphingolipids from the brain of the macaque were compared to these from the human brain.

Animals↗
PubMed1994

Peroxisomal beta-oxidation of branched chain fatty acids in rat liver. Evidence that carnitine palmitoyltransferase I prevents transport of branched chain fatty acids into mitochondria.

Fatty acid beta-oxidation was investigated in highly purified mitochondrial and peroxisomal preparations from rat liver. Under isotonic conditions, pristanic and homophytanic acid beta-oxidation in purified peroxisomes was severalfold greater compared to the oxidation in purified mitochondria. Branched chain fatty acid beta-oxidation in purified mitochondria was very low, and the oxidation was not stimulated by exogenous L-carnitine or L-malate. In contrast, stearic acid beta-oxidation by purified mitochondria depended upon exogenous L-carnitine, and the oxidation was stimulated by L-malate. Both mitochondrial and peroxisomal beta-oxidation of branched chain fatty acids was strongly inhibited by fatty acid-free bovine serum albumin, whereas stearic acid oxidation was either unaffected or slightly inhibited by bovine serum albumin. The results presented clearly indicate that branched chain fatty acids are mainly degraded in peroxisomes in rat liver. Branched chain fatty acids were efficiently converted to coenzyme A thioesters by purified mitochondria, peroxisomes, and microsomes. Although pristanic and phytanic acids were rapidly converted to pristanoyl-CoA and phytanoyl-CoA, respectively, they were not converted to carnitine esters by mitochondrial outer membranes. The results indicate that acyl-CoA synthetase and carnitine acyltransferase located at the mitochondrial outer membranes regulate entry of branched chain fatty acids into mitochondria. Mitochondrial carnitine acyltransferase I appears to be highly specific for straight chain fatty acids and restricts entry of branched chain fatty acids into mitochondria. Thus, branched chain fatty acids which cannot be transported across the mitochondrial membranes via the carnitine acyltransferase system are directed to peroxisomes for beta-oxidation. The results reported indicate that phytanic acid, the fatty acid which can be initially degraded by alpha-oxidation due to the presence of a beta-methyl group in the molecule, cannot be transported across the mitochondrial membranes. The data presented strongly suggest that phytanic acid alpha-oxidation occurs in organelles other than mitochondria and possibly in peroxisomes.

Acyl Coenzyme A↗
PubMed2004

Integrated circuits protection with the Langmuir-Blodgett Films.

Integrated circuits (ICs) can be protected from the environment with the encapsulating polymer layer. Protection properties of such a polymer barrier-layer depend strongly from the structure of thin region where polymer stays in direct contact with the IC surface. One of the interesting questions is how thick should this interphase film be to assure good environmental protection to the IC conductor lines, preventing from their corrosion and failure. In order to answer this question a set of electronic testers with Al conductor lines were modified with 1, 20, 50 multilayers of stearic acid molecules deposited in the Langmuir-Blodgett (LB) transfer method. Next, the electronic testers were subjected to the highly accelerated aging conditions (100% relative humidity (RH), 100 degrees C) for a period of up to 800 h and conductor lines resistivity changes were monitored. Electronic testers modified with 20 multilayers of stearic acid were better protected from the accelerated aging conditions than the testers modified with 1 monolayer or 50 multilayers. Obtained results suggest that the thickness of the interphase region separating IC surface and polymeric film should be in the range of 10 nm.

Electric Impedance↗
PubMed1999

Growth mechanisms in melt agglomeration with a low viscosity binder.

Lactose monohydrate was melt agglomerated in an 8-l high shear mixer using stearic acid as meltable binder. The impeller speed was varied at six levels, and the temperature of the heating jacket was varied at three levels. The agglomerate growth mechanisms were found to be different from those observed in previous melt agglomeration experiments. This is attributed to the low viscosity of the molten stearic acid. A higher impeller speed and a higher jacket temperature resulted in an agglomerate growth that was markedly affected by comminution and accordingly gave rise to agglomerates of a wider size distribution and a higher porosity. A lower impeller speed and a lower jacket temperature resulted in smoother and more spherical agglomerates.

Chemistry, Pharmaceutical↗
PubMed1975

Distribution of fatty acids during germination of cottonseeds.

Gas chromatographic determination of the fatty acids in the seeds of cottonseed (Gossypium sp.) showed linoleic, palmitic, oleic, and stearic acids, with linoleic acid being the major component. Changes in the composition of fatty acids during various stages of germination were measured in the cotyledons and in the roots. A decrease in the content of all the fatty acids and an 8-fold increase in the moisture content of the cotyledons were observed during the 10 days of germination. There were no significant changes in the fatty acid contents of the roots with the exception of those in linoleic acid which increased by 50 percent during 4-10 days of germination. The possible significance of these changes is discussed.

Cell Division↗
PubMed1982

Deposition and maturation of eggs of Schistosoma mansoni in vitro: importance of fatty acids in serum-free media.

A serum-free medium which supports miracidial development in some eggs deposited by adult Schistosoma mansoni in vitro is described. Derivation of the medium involved examination of the supportiveness of nine chemically defined media, selection of one promoting the highest degree of worm oviposition, and supplementation of the latter with various serum fractions. The serum fraction supporting egg maturation was nondialyzable, and precipitated at 50-60% ammonium sulfate saturation. This fraction could be replaced by bovine serum albumin; however, the supportive activity disappeared if this material was delipidated. Addition of soybean lecithin, or stearic acid, to fatty-acid-free, albumin-supplemented media yielded intermediate results, while similar addition of other nonesterified fatty acids proved non stimulatory. A fatty acid mixture, rich in stearic acid, was then developed which, when added to delipidated-albumin supplemented media, supported a degree of egg development comparable to that obtained with media supplemented with 8% newborn calf serum.

Animals↗
PubMed1988

Fluorescence study of the membrane-perturbing action of sodium caprylate as related to promotion of drug absorption.

The medium-chain fatty acid sodium caprylate released 6-carboxyfluorescein (CF), a model compound of water-soluble drugs, from the rat small intestinal brush border membrane (BBM) vesicles and liposomes containing CF. Caprylate caused a decrease in the fluorescence polarization of dansyl chloride, fluorescein isothiocyanate, and eosin maleimide covalently labeled to BBM. This indicates a perturbation of the BBM. However, no change in the fluorescence polarization of lipid-soluble fluorescent probes (2-(9-anthroyloxy) stearic acid, 12-(9-anthroyloxy) stearic acid, and 1,6-diphenyl-1,3,5-hexatriene) labeled to BBM was produced by caprylate. These findings indicate that caprylate can increase the permeability of the plasma membranes through the perturbation of the membranes. These actions of caprylate on membranes are considered one possible mechanism by which it promotes the absorption of water-soluble and poorly absorbed drugs.

Animals↗
PubMed1998

Effects of hydrolysis of milk glycerides on the antimutagenicity of a hexane extract of milk.

Reconstituted nonfat dry milk was treated with different amounts of lipase from Pseudomonas fluorescens. Hexane extracts of treated milks were dissolved in dimethylsulfoxide and assayed for antimutagenicity using the Ames test (Salmonella typhimurium TA 100) against N-methyl, N'-nitro, N-nitrosoguanidine. Anti-N-methyl, N'-nitro, N-nitrosoguanidine activity increased significantly as the amount of added lipase increased. At the highest lipase concentration tested, activity increased 5-fold, suggesting that liberated fatty acids contributed to the increased antimutagenicity. The activities of mixtures of pure fatty acids on antimutagenesis were examined using the Ames test. At the lowest concentrations tested, mixtures of palmitic and stearic acids and mixtures of palmitic and isopalmitic acids exhibited greater activity than did the individual acids. At all doses tested, mixtures of the monoacylglycerides of palmitic and stearic acids exhibited the same activity as the individual components. Quantification of fatty acids in milk and yogurt by gas chromatography indicated a 2 to 20-fold greater content of free fatty acids in yogurt. The increase in free fatty acids may contribute to the increase in antimutagenicity of yogurt relative to that of milk.

Animals↗
PubMed1985

Reduction in the stearic to oleic acid ratio in human malignant liver neoplasms.

Total lipid extracts of liver tissue from 14 patients with primary and secondary liver tumours were analysed for relative values of saturation of 18 carbon chain length fatty acids (C18FA). The saturation indices (ratio C18S:C18u) of the tumour areas were significantly and consistently lower than the corresponding values in the non-tumour areas (P less than 0.001). It is proposed that the relative increase in unsaturated C18FA (oleic acid) could prove to be a chemical marker reflecting deficient cellular control of the desaturation of stearic acid.

Adult↗
PubMed2004

Effect of drug solubility and different excipients on floating behaviour and release from glyceryl monooleate matrices.

Glycerol monooleate (GMO) matrix was found to be a gastro-retentive carrier system suitable for both polar and as well as non-polar drugs. Chlorpheniramine maleate (CPM) and diazepam (DZP) were used as model drugs. Effect of PEG 4000, PEG 10000, and stearic acid on floatability and release profile was studied. Water uptake increased with increase in the loading of polar drug (CPM) and decreased with non-polar drug (DZP). Similar effect was found to occur in case of drug release. PEGs increased the release up to certain concentration and decreased thereafter. Drug release decreased linearly with concentration of stearic acid. The type and extent of mesophases formed were significantly affected by the nature of drug, excipients and their concentration. Thus the selection of suitable excipients depending on polarity of drug, could help to modulate the floatability and release profile from GMO matrices.

Chemistry, Pharmaceutical↗
PubMed1981

Ice crystals specifically decorate hydrophilic sites on freeze-fractured models membranes.

Experiments with yeast plasmalemma fracture faces, produced at -196 degrees C and exposed to pure water vapor before replication, showed a "specific decoration" with ice crystals of those pits in the extraplasmatic face where the matching particles of the plasmatic face had been removed (H. Gross et al., J. Cell Biol. 79 (1978) 646). THe preferred growth of cubic ice crystals on the small depressions of the extraplasmatic face could be caused by the cavity-like character of the surface relief or by physicochemical surface properties which differ from those of the surrounding lipid fractures face. The following results suggest that not geometric or topographic but physicochemical surface properties are responsible for the trapping of water molecules in the regions of the depressions. Freeze-fractured multilamellar stearic-acid crystals and cardiolipin liposomes exhibit after fracturing hydrophobic faces and hydrophilic steps (bimolecular steps with two polar head groups in half of the step height) which act as preferential nucleation sites and lead to the formation of discrete ice crystals mainly along the steps. Multilamellar crystals of the paraffin n-octatriacontane (C38H78) exhibit after freeze-fracturing hydrophobic faces and geometrically identical, but hydrophobic steps. In contrast to stearic acid these steps do not act as preferential nucleation sites.

Alkanes↗