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PubMed1998

[Modification of basic pancreatic trypsin inhibitor by fatty acid derivatives].

A procedure was developed for the modification of basic pancreatic trypsin inhibitor (BPTI) by N-hydroxysuccinimide esters of oleic and stearic acids in a DMSO-DMF-dioxane-pyridine mixture with a temporary citraconyl protection of the amino group belonging to its active site. The BPTI derivatives containing from one to three acylated amino groups were obtained. It was shown that the hydrophobized BPTI with one amino group modified retained practically the full activity of the native inhibitor. An increase up to three acylated groups resulted in a decrease in the specific activity of the inhibitor to 28% of the initial activity. An increase in hydrophobicity of the modified inhibitors was demonstrated by the spectral method and by the distribution in a water-triton X-114 system.

Acylation↗
PubMed2005

Stearic, oleic, and linoleic acids have comparable effects on markers of thrombotic tendency in healthy human subjects.

Because human studies concerning the effects of stearic acid on thrombotic tendency are inconsistent, we compared the effects of stearic acid with those of its unsaturated derivatives, oleic acid and linoleic acid. In this randomized, crossover study, 45 subjects (27 women and 18 men) consumed, in random order, 3 experimental diets, each for 5 wk. Diets contained approximately 38% of energy as fat. Dietary compositions were the same except for 7% of energy from stearic, oleic, or linoleic acids. At the end of each period, ex vivo and in vitro platelet aggregation, and variables of coagulation, fibrinolysis, and hematology were evaluated. In men, ex vivo platelet aggregation time as measured by filtragometry (P = 0.036 for diet effects) was favorably prolonged during consumption of the linoleic acid diet compared with the stearic acid diet (P = 0.040), but there was no difference with consumption of the oleic acid diet (P = 0.198). In vitro platelet aggregation induced by collagen and ADP, and variables of coagulation (factor VII amidolytic activity and concentrations of fibrinogen and prothrombin fragment 1 and 2) and fibrinolysis [plasminogen activator inhibitor (PAI) activity and concentrations of tissue plasminogen activator (tPA)/PAI-1 complexes] did not differ among the 3 diets. The mean platelet volume of the subjects decreased during consumption of the stearic acid diet by 0.32 fL compared with the oleic acid diet (P < 0.001) and by 0.35 fL compared with the linoleic acid diet (P < 0.001). In conclusion, our results do not suggest that stearic acid is highly thrombogenic compared with oleic and linoleic acids.

Adenosine Diphosphate↗
PubMed1992

Irradiation of Langmuir-Blodgett multilayer preparations of phospholipids and a fatty acid. 2: Effect of X-radiation.

X-irradiation of Langmuir-Blodgett (LB) preparations of stearic acid with doses up to a few thousand Gy produced no change of measured electrical conductance in the direction perpendicular to the stacked monolayers. However, irradiation of LB preparations of phospholipids resulted in increased conductance. The effect depended on dose, but not on dose rate and, unlike the corresponding effect of UV-radiation, did not reverse at room temperature. For doses up to about 2 kGy the increased conductance fell away over some tens of minutes if the temperature was raised above 45 degrees C. For doses between 2 and 60 kGy the conductance increased linearly, but less rapidly than the initial rise and the increase was only partly reversible by heating. The rate of increase of conductance rose again for doses above about 60 kGy and for these doses the increase could not be reversed on heating. It is suggested that X-irradiation left molecules in a damaged but reversible state similar to that found after UV irradiation; and that subsequent excitation and ionization damaged the molecules irreversibly.

Cell Membrane↗
PubMedDate not supplied

Hyperlipidemia in acute lymphoblastic leukemia.

Studies were conducted on lipemic serum obtained from a 26 month old male to determine possible mechanisms for the association of a Type V hyperlipidemic phenotype with advanced lymphoblastic leukemia (ALL). Antibodies to apolipoproteins and endogenous heparin were not detected as previously reported. Fatty acid analysis of the triglyceride esters revealed a high proportion of stearic-acid (18:0) which was associated with a slower in vitro degradation of very low density lipoproteins (VLDL) by human milk lipoprotein lipase (LPL). This suggests that a cause of the hyperlipidemia could be abnormal composition of triglycerides which render the VLDL a poor substrate for lipoprotein lipase. Hyperlipidemia in leukemia may be more prevalent than previously realized since nine other cases of newly diagnosed ALL have been studied who had moderate hypertriglyceridemia associated with elevated ApoB and low ApoA-I levels, but normal triglyceride composition. These findings suggest that the abnormal triglyceride composition is a late feature of the hyperlipidemia in leukemia, as observed in the case studied.

Adult↗
PubMed1975

Vitreous structure, IV. Chemical composition of the insoluble residual protein fraction from the rabbit vitreous.

Analysis of the structural proteins in the rabbit vitreous showed that the hydroxyproline content was 3.1 per cent w/w compared to a value of 10.9 per cent w/w for equivalent samples obtained from cattle. In contrast to the discreet fibers in bovine vitreous, the rabbit constituents occur as an aggregate of fibrils with a diameter of 15 to 20 å. The amino acid and carbohydrate composition was similar to vascular basement membrane and isolated fractions contained significant amounts of palmitic and stearic acids. The data indicate that the variability of vitreous structure in different species is not only quantitative, but also qualitative. It is suggested that in the rabbit the structural proteins may be derived primarily from the atrophied hyaloid system and that little, if any, secondary vitreous formation occurs in this animal.

Amino Acids↗
PubMed1970

Autoxidation of insect lipids: inhibition on the cuticle of the American cockroach.

The major hydrocarbon, cis, cis-6,9-heptacosadiene, of Periplaneta americana cuticles and oothecae solidifies in air by autoxidation. The reaction resembles the autoxidation of other dienes by known free radical mechanisms and yields stearic acid, stearal, hexanoic acid, and hexanal. On the cuticle, autoxidation is inhibited by polyhydric phenols.

Air↗
PubMed2004

The determination of the asymmetrical stereochemical distribution of fatty acids in triacylglycerols.

The fatty acid distribution in triacylglycerols (TAGs) is a factor that contributes to the intrinsic properties of oils from different species variants. Many hypotheses have been proposed to explain the specific distribution of fatty acids in the different naturally occurring oils. Currently, the 1,3-random-2-random theory is more or less accepted, but it has been widely shown that most vegetable oils do not behave randomly in the sn-1 and sn-3 stereochemical positions. For this reason, complex methodologies have been developed to analyze the fatty acid composition of the three stereochemical positions in TAGs. In this article, we propose that by calculating the asymmetric alpha coefficient, the stereochemical asymmetry of fatty acids in TAG molecular species can be defined. This coefficient reflects the relative content of fatty acids at the sn-1 and sn-3 positions and may overcome the problems found mainly with complex sn-1, sn-2, and sn-3 stereochemical analysis of fatty acids in TAG. The alpha coefficient is calculated from the fatty acid, sn-2 fatty acid, and TAG composition of the oil. Indeed, through this coefficient, it has been possible to show that, despite having the same overall content, the stearic acid distribution in the sn-1 and sn-3 positions is not random in some oils.

Dietary Fats↗
PubMed1998

Cell-mediated oxidation of LDL: comparison of different cell types of the atherosclerotic lesion.

The three major cell types of the human atherosclerotic lesion--macrophages (Mø), smooth muscle cells (SMC) and endothelial cells (EC)--were compared for their ability to oxidise low density lipoprotein (LDL) in vitro under identical conditions. Near-confluent cultures were incubated for up to 48 h with 50 microg protein/ml LDL in Ham's F10 medium supplemented with 7 microM Fe2+. All three cell types oxidised LDL readily using our culture conditions. After 24 and 48 h, the degree of LDL oxidation was in the order: Mø > SMC > EC when based on cell growth area and EC > SMC > Mo when based on cellular DNA content. However, LDL oxidation in vitro progressed more slowly between 24 and 48 h, probably due to increasing toxicity to the cells and/or depletion of polyunsaturated fatty acids. We therefore compared the time of onset of LDL oxidation. The earliest increase in LDL oxidation was always apparent with SMC. Gas chromatography revealed that LDL oxidation by all three cell types followed a similar pattern. The polyunsaturated fatty acids linoleic acid (18:2) and arachidonic acid (20:4) were depleted (to 10.3-18.1% and 4.5-24.7% respectively, compared to native LDL), whereas the content of stearic acid (18:0) and oleic acid (18:1) remained unchanged. Cholesterol was depleted (to 54.1-75.6% of native LDL) with a concomitant rise in 7 -hydroxycholesterol (to 60.6-128.1 microg/mg LDL). This corresponds to a conversion of 4.9, 9.5 and 10.4% of LDL cholesterol in EC-, SMC- and Mo-modified LDL respectively. All three cell types showed significant toxicity in the oxidising culture after 24h. The possible relevance to LDL oxidation in atherosclerosis is discussed.

Aorta↗
PubMed1992

Lipid analysis of the major salivary glands in streptozotocin-diabetic rats and the effects of insulin treatment.

Two separate sets of experiments were performed on female Wistar rats made diabetic with streptozotocin: (1) a time-course study where groups of three animals were removed at weekly intervals, up to 4 weeks after induction of diabetes, with an age-matched group of control (normal) animals kept for 4 weeks; (2) six further animals were made diabetic and kept for 7 weeks; three of these were given insulin in the final week. At the required time the animals were anaesthetized and the salivary glands removed and preserved by fixation or freezing. The frozen tissues were later homogenized and the protein and lipid content analysed. Histologically, intracellular lipid droplets had accumulated in the majority of the diabetic salivary glands. In the time-course experiment, the visible amount of intracellular lipid reached a maximum after 2 weeks and then decreased, with a concomitant disappearance of interstitial lipid. The increased lipid content was not attributable to any one class. The fatty acid profiles of the glands showed an increase in the percentages of C18:0 (stearic acid) and C18:2w6 (linoleic acid) and a decrease in the percentages of C18:1w9 (oleic acid) and C20:4w6 (arachidonic acid). After 1 week of insulin treatment the lipid content and the fatty acid profiles returned to normal. Thus the effect of insulin on salivary gland lipid metabolism is rapid both in its occurrence and reversibility. The effects seen in the diabetic rats are considered to be due to a lack of insulin and not to the presence of streptozotocin.

Animals↗
PubMed1993

ATP leakage from ELD cells after exposure to stearic, monochlorostearic, dichlorostearic, and oleic acids.

The capacity of stearic, monochlorostearic, dichlorostearic and oleic acids to cause membrane damage was measured as their ability to induce leakage of adenosine triphosphate (ATP) from mammalian tumour cells in vitro. Chlorinated stearic acids, and oleic acid, caused ATP leakage at lower concentrations than normal stearic acid. The membrane disturbing properties are suggested to be a result of the different molecular geometries of the chlorinated stearic acids, and oleic acid, compared to non-chlorinated stearic acid.

Adenosine Triphosphate↗
PubMed1995

Comparison of solutol HS 15, Cremophor EL and novel ethoxylated fatty acid surfactants as multidrug resistance modification agents.

Some well-known fatty acid ester surfactants, e.g., Cremophor EL and Solutol HS 15, are modulators of multidrug resistance in vitro and in vivo. Because they are polydisperse, and their active component(s) have not been identified, the therapeutic potential of such surfactants is unclear. To better define the active components of Solutol HS 15 and to make more potent surfactant multidrug resistance modulators, highly purified C-18 fatty acids were esterified with ethylene oxide at 5-200 molar ratios. Unexpectedly, ethylene oxide esters of pure 12-hydroxy stearic acid, the major components of Solutol HS 15, displayed negligible resistance modification activity compared with Solutol HS 15 itself or to stearic and oleic acid esters synthesized under identical conditions. Since oleic acid esters appeared to have good activity, a series of these compounds was prepared to determine the optimal ethylene oxide/fatty acid ratio. The optimal ratio was found to be 20 mole ethylene oxide: I mole fatty acid, with a steep decline in activity for products made with ratios above and below the optimum. The most active oleic acid ester, designated CRL 1337, was 8.4-fold as potent as Solutol HS 15 and over 19-fold as potent as Cremophor EL in promoting rhodamine 123 accumulation in multidrug-resistant KB 8-5-11 cells in vitro. Our results show that the structure of the hydrophobic domain (fatty acid) of surfactants as well as its hydrophile-lipophile balance are critical in determining the potency of surfactants as reversing agents.

Antineoplastic Agents↗
PubMed2004

Resonant x-ray reflectivity from a bromine-labeled fatty acid Langmuir monolayer.

Resonant x-ray reflectivity exploits the energy dependence of atomic scattering factors to locate resonant atoms within the electron density distribution of thin films. We apply the technique to a monolayer of bromo-stearic acid at the air/water interface. The data collection protocol employed cycles through several energies in the vicinity of the bromine K absorption edge and verifies that the energy dependencies observed are indeed resonant effects. The analysis specifies the location of the Br atom with sub-angstrom precision and must consider both the real and imaginary parts of the changes in the scattering factor to be consistent with the known structure and stoichiometry of this test case.

Algorithms↗
PubMed1992

Effect of dietary cis and trans fatty acids on serum lipoprotein[a] levels in humans.

Serum lipoprotein[a] (Lp[a]) is a strong risk factor for coronary heart disease. We therefore examined the effect of dietary fatty acid composition on serum Lp[a] levels in three strictly controlled experiments with healthy normocholesterolemic men and women. In Expt. I, 58 subjects consumed a control diet high in saturated fatty acids for 17 days. For the next 36 days, 6.5% of total energy intake from saturated fatty acids was replaced by monounsaturates plus polyunsaturates (monounsaturated fatty acid diet; n = 29) or by polyunsaturates alone (polyunsaturated fatty acid diet; n = 29). Both diets caused a slight, nonsignificant, increase in median Lp[a] levels, with no difference between diets. In Expt. II, 10% of energy from the cholesterol-raising saturated fatty acids (lauric, myristic, and palmitic acid) was replaced by oleic acid or by trans-monounsaturated fatty acids. Each of the 59 participants received each diet for 3 weeks in random order. The median level of Lp[a] was 26 mg/l on the saturated fatty acid diet; it increased to 32 mg/l (P less than 0.020) on the oleic acid diet and to 45 mg/l (P less than 0.001) on the trans-fatty acid diet. The difference in Lp[a] between the trans-fatty acid and the oleic acid diets was also highly significant (P less than 0.001). Expt. III involved 56 subjects; all received 8% of energy from stearic acid, from linoleic acid, or from trans-monounsaturates, for 3 weeks each. All other nutrients were equal.(ABSTRACT TRUNCATED AT 250 WORDS)

Dietary Fats↗
PubMed2004

Lipid binding in rice nonspecific lipid transfer protein-1 complexes from Oryza sativa.

Nonspecific lipid transfer proteins (nsLTPs) facilitate the transfer of phospholipids, glycolipids, fatty acids and steroids between membranes, with wide-ranging binding affinities. Three crystal structures of rice nsLTP1 from Oryza sativa, complexed with myristic (MYR), palmitic (PAL) or stearic acid (STE) were determined. The overall structures of the rice nsLTP1 complexes belong to the four-helix bundle folding with a long C-terminal loop. The nsLTP1-MYR and the nsLTP1-STE complexes bind a single fatty acid while the nsLTP1-PAL complex binds two molecules of fatty acids. The C-terminal loop region is elastic in order to accommodate a diverse range of lipid molecules. The lipid molecules interact with the nsLTP1-binding cavity mainly with hydrophobic interactions. Significant conformational changes were observed in the binding cavity and the C-terminal loop of the rice nsLTP1 upon lipid binding.

Amino Acid Sequence↗
PubMed2002

Regulation of triacylglycerol and phospholipid trafficking by fatty acids in newborn swine enterocytes.

We (Wang H, Berschneider HM, Du J, and Black DD. Am J Physiol Gastrointest Liver Physiol 272: G935-G942, 1997; Wang H, Lu S, Du J, Yao Y, Berschneider HM, and Black DD. Am J Physiol Gastrointest Liver Physiol 280: G1137-G1144, 2001) previously showed that different fatty acids influence synthesis and secretion of triacylglycerol (TG) and phospholipid (PL) in a newborn swine enterocyte cell line (IPEC-1). The most striking effects were produced by stearic acid (SA; 18:0), which modestly affected TG and PL synthesis but reduced TG and PL secretion, and by eicosapentaenoic acid (EPA; 20:5), which reduced TG and PL synthesis and TG secretion relative to oleic acid (OA; 18:1). To define the mechanism of these effects, differentiated IPEC-1 cells were incubated for 24 h with OA, SA, or EPA and [(3)H]glycerol. Endoplasmic reticulum (ER) and Golgi (G) content of labeled lipids and apolipoprotein (apo) B and apoAI protein were measured. Relative to OA, SA did not impair ER TG synthesis, but reduced movement of labeled TG from ER to G. EPA impaired both ER TG synthesis and movement of labeled TG from ER to G. PL followed the same pattern, except ER synthesis of PL was relatively unaffected by EPA. Carbonate treatment demonstrated decreased partitioning of labeled lipid from ER membrane to lumen in EPA-treated cells. Organelle apoB and apoAI content demonstrated opposite patterns after SA and EPA incubation. We conclude that SA and EPA adversely influence immature enterocyte ER to G lipid trafficking, compared with OA. Furthermore, EPA inhibits ER lipid synthesis and transfer of membrane lipid to luminal particles. Regulation of apoAI ER to G trafficking is independent of that of apoB.

Animals↗
PubMed2006

Augmentation of vaccenate production and suppression of vaccenate biohydrogenation in cultures of mixed ruminal microbes.

To increase ruminal outflow of trans-vaccenic acid (t-VA), a new strain of Butyrivibrio fibrisolvens (MDT-10) was isolated that has a great ability to hydrogenate linoleic acid (LA) to t-VA. When strain MDT-10 was added to the batch cultures of mixed ruminal microbes (1% of the total number of viable ruminal bacteria), LA conversion to t-VA increased greatly; after 3 h, t-VA levels were > 4-fold higher than the control. By 10 h, all of the t-VA was hydrogenated to stearic acid. However, when a new strain of Bifidobacterium adolescentis (HF-11), which has a high capacity for incorporation of t-VA, was added in conjunction with MDT-10 (1% of the total number of ruminal bacteria), t-VA levels after 10 h were 6 times higher than with MDT-10 alone. These results suggest that t-VA produced by MDT-10 was incorporated into HF-11 cells, resulting in protection of t-VA from t-VA-hydrogenating microbes. Similar results were obtained in a continuous culture of mixed ruminal microbes in which addition of HF-11 simultaneously with MDT-10 increased the amount of t-VA in the effluent 2.5-fold. Both MDT-10 and HF-11 appeared to grow readily in the presence of mixed ruminal microbes. Sixty-two percent of t-VA incorporated by HF-11 was present in the free form, whereas 19, 15, and 3%, respectively, were incorporated into monoacylglycerol, glycerophospholipid, and diacylglycerol fractions. Because these lipids can be digested in the small intestine, it is likely that most t-VA in HF-11 cells is absorbed. Thus, introduction of MDT-10 and HF-11 simultaneously to the rumen might increase the amount of t-VA absorbed and might consequently increase the conversion of t-VA to conjugated linoleic acid in tissue.

Animals↗
PubMed2005

Identification of lipid binders in old oil paintings by separation of 4-bromomethyl-7-methoxycoumarin derivatives of fatty acids by liquid chromatography with fluorescence detection.

A HPLC-fluorescence method for identification of drying oils from binding media or protective film used in pictorial works of art prior to conservation or restoration is proposed. Fluorescence derivatization of fatty acids released by hydrolysis of structural drying oils is studied. The derivatization reagent was 4-(bromomethyl)-7-methoxycoumarin with 18-crown-6 as catalyst. Mobile phase was programmed from methanol-water (90:10 v/v) to methanol-water (100:0 v/v) in 25 min. The excitation and emission wavelengths were 325 and 395 nm, respectively. Under these chromatographic conditions, coumarin derivatives of myristic, palmitic, oleic and stearic acids were satisfactorily resolved. The method shows good sensitivity, with a detection limit of 6.0 x 10(-8) mmol, and good linearity between 1.0 x 10(-7) and 1.8 x 10(-4) mmol of each analyte. Peak area ratios among fatty acids derivatives, especially the stearic acid/palmitic acid peak area ratio, are useful to identify the drying oils. The proposed method has been successfully applied to artistic samples from items of the cultural heritage of Valencia (Spain).

Chromatography, High Pressure Liquid↗