bluuebunny/crossref_metadata_2025_split huggingface dataset:
Esterification of palmitic acid in swine aortic homogenates
Authors: Huang William Y. , Kumerow Fred A. 
Published: November 2006

AbstractThe incorporation of [1‐14C] palmitic acid into tissue lipids of the medial and intimal layers of swine aortic homogenates was investigated. The homogenates obtained were metabolically active as indicated by their ready incorporation of labeled palmitic acid into phospholipids, diglycerides and triglycerides in the presence of α‐glycerophosphate in the incubation medium. Predominantly, labeling of phospholipids and especially of phosphatidylcholine was found when α‐glycerophosphate or lysolecithin served as the fatty acid acceptor. Glycerol and monoolein did not serve as fatty acid acceptors. More than 98% of the radioactivity was recovered as the phosphatidylcholine fraction at the level of 0.64 μmoles/ml of lysolecithin in the incubation medium.
Effects of essential fatty acid deficiency on prostaglandin synthesis and fatty acid composition in rat renal medulla
Authors: Dunham E. W. , Balasingam M. , Privett O. S. , Nickell E. C. 
Published: November 2006

AbstractStudies are reported on the capacity of isolated rat renal papilla (inner medulla) to synthesize and release prostaglandin (PG) E from endogenous and exogenous precursor(s) during development of an essential fatty acid (EFA) deficiency in the rat. Weanling (21‐day‐old) male Sprague‐Dawley rats were fed a fat‐free diet supplemented with either 5% hydrogenated coconut oil (HCO) or 5% safflower oil (SO). At approximately 3, 6 and 7 weeks (6, 9 and 10 weeks of age), groups of animals fed each diet were killed for studies of PGE synthesis in the renal papillae. Differences in the fatty acid composition of the papillae lipids of the animals of each group were also determined. The in vitro production of PGE from endogenous precursor(s) was significantly reduced in the papillae from the 6‐week‐old rats fed the HCO diet compared to the control (SO) rats, and appeared to be near maximally depressed in the 10‐week‐old animals compared to that of animals fed an EFA deficient diet for over a year in an accessory experiment. Analyses of the fatty acids of the papillae lipids of the HCO groups showed that the levels of 18∶2 and 20∶4 were markedly reduced, and those of 16∶1, 18∶1 and 20∶3 were elevated compared to the controls even in the 6‐week‐old animals, typical of an EFA deficiency. The papillae lipids of the animals fed the HCO diet were also depleted of their stores of 22∶4ω6. A fatty acid believed to be derived by chain elongation of 20∶3ω9, 22∶3, was found in large concentrations in the papillae triglycerides of the EFA deficient rats. Incubations of exogenous arachidonic acid (20∶4) in homogenates and tissue slices of the papillae of the HCO dietary groups showed that the PG synthetase was not impaired by an EFA deficiency. The rate of PGE synthesis in the papillae of the EFA deficient animals was generally enhanced when exogenous 20∶4 was added, indicating that the concentration of available precursor(s) is a primary factor in the control of PGE synthesis in the papilla of the rat.
Availability of lysophosphatidylcholine in single bilayer vesicles for hydrolysis by lysophospholipase
Authors: de Oliveira Filgueiras O. M. , van den Besselaar A. M. H. P. , van den Bosch H. 
Published: November 2006

AbstractSingle bilayer vesicles were prepared from total rat liver microsomal lipids to which 5 mol% lysophosphatidylcholine had been added. The availability of lysophosphatidylcholine for enzymatic hydrolysis by lysophospholipase (EC 3.1.1.5) was found to be higher in vesicles prepared by the cholate dispersion technique when compared with sonicated vesicles. Sepharose 4 B chromatography showed that the vesicles prepared by the cholate technique were smaller than those prepared by sonication. This is in contrast to previous observations for egg phosphatidylcholine vesicles. Total rat liver microsomal extracts were found to contain proteolipid, which could be removed by ether precipitation. Cholate vesicles prepared from proteolipid‐free extracts were still smaller than sonicated vesicles from this extract. Experiments with [14C] dextran entrapped in the vesicles indicate that there is no loss of the permeability barrier of the vesicles for high molecular weight solutes during vesicle treatment with lysophospholipase. The high availability of lysophosphatidylcholine in cholate vesicles of total rat liver microsomal lipids is discussed in terms of a highly asymmetric distribution of lysophosphatidylcholine over the inner and outer monolayer of the bilayer.
Study of the two pathways for arachidonate oxygenation in blood platelets
Authors: Dutilh C. E. , Haddeman E. , Jouvenaz G. H. , Ten Hoor F. , Nugteren D. H. 
Published: November 2006

AbstractDuring collagen‐induced blood platelet aggregation, arachidonic acid is set free from membrane phospholipids and subsequently converted into 12‐hydroxyeicosatetraenoic acid by arachidonate lipoxygenase and into thromboxane A2, 12‐hydroxyheptadecatrienoic acid (HETE) and malondialdehyde by cyclooxygenase and thromboxane synthase. Lipoxygenase and cyclooxygenase have optimal activity at neutral to basic pH, while the thromboxane synthase is pH‐independent between 5 and 9. These enzymes are membrane‐bound. The cyclooxygenase is rapidly inactivated upon membrane disruption by nonionic detergents or phospholipid degradation with phospholipase A2. It was found that platelet phospholipase A2 preferentially splits off fatty acid with four double bonds. Eicosatetraynoic acid was used to investigate the physiological function of the arachidonate lipoxygenase during collagen‐induced aggregation of rat blood platelets. This fatty acid is a more efficient inhibitor of lipoxygenase than of cyclooxygenase. At an inhibitor concentration of 0.6 μg/ml, platelet aggreation, 12‐hydroxyeicosatetraenoic acid production as well as 15‐hydroxytryptamine release are completely inhibited, while there is an apparent stimulation of the cyclooxygenase. These results indicate that arachidonate lipoxygenase is essential for irreversible blood platelet aggregation.
Different metabolism of saturated and unsaturated long chain plasma free fatty acids by intestinal mucosa of rats
Authors: Gangl A. , Kornauth W. , Mlczoch J. , Sulm O. , Klose B. 
Published: November 2006

AbstractDuring fat absorption, unsaturated long chain fatty acids are esterified at a higher rate than saturated fatty acids of similar chain length. This phenomenon has been attributed to differences in the binding affinity of fatty acids to a cytosolic fatty acid‐binding protein. As intestinal mucosa utilizes plasma free fatty acids as well, we investigated whether long chainplasma free fatty acids of different degree of saturation are metabolized also at different rates.3H‐Palmitic and14C‐linoleic acid complexed to rat serum were injected rapidly into a tail vein of fasting rats. One, 2 and 4 min later there was no difference between3H and14C‐radioactivity in intestinal mucosa, suggesting equal initial uptake of the two labeled fatty acids from plasma. Despite their equal uptake, the incorporation of the isotopes into ester lipids was significantly different, however: at 2 min, 53.1±3.9% of3H and 73.8±4.6% of14C were recovered in ester lipids. Phospholipids and triglycerides accounted for most of the mucosal3H and14C. At 4 min, a similar distribution of isotopes in intestinal mucosal metabolites was found. These data show that despite equal initial uptake by intestinal mucosa unsaturated long chain fatty acids taken up from plasma are esterified to a higher and oxidized to a lower extent than saturated plasma free fatty acids. Unsaturated plasma free fatty acids, therefore, may provide a more important source of fatty acids for endogenous intestinal lipoprotein lipids than saturated plasma free fatty acids. It is speculated that the fatty acid binding protein might be operative not only in the intracellular transport and metabolism of luminal fatty acids but of plasma free fatty acids as well.
Biosynthesis of cholic acid in rat liver: Formation of cholic acid from 3α, 7α, 12α‐trihydroxy‐ and 3α, 7α, 12α, 24‐tetrahydroxy‐5β‐cholestanoic acids
Authors: Gustafsson Jan 
Published: November 2006

AbstractConversion of 3α,7α,12α‐trihydroxy‐5β‐cholestanoic acid into 3α,7α,12α24‐tetrahydroxy‐5β‐cholestanoic and cholic acids was catalyzed either by the mitochondrial fraction fortified with coenzyme A, ATP, MgCl2 and NAD or by the combination of microsomal fraction and 100,000 x g supernatant fluid fortified with coenzyme A, ATP and NAD. 24‐Hydroxylation and formation of cholic acid occurred at similar rates with the 25R‐ and the 25S‐forms of 3α,7α,12α‐trihydroxy‐5β‐cholestanoic acid. The 25R‐ and 25S‐forms of 3α,7α,12α‐trihydroxy‐and 3α,7α,12α,24‐tetrahydroxy‐5β‐cholestanoic acids were administered to bile fistula rats. Labeled cholic acid was isolated from the bile. The initial specific radioactivity of cholic acid was higher and the disappearance of radioactivity more rapid after administration of 3α,7α,12α‐trihydroxy‐5β‐cholestanoic acid than of 3α,7α,12α,24‐tetrahydroxy‐5β‐cholestanoic acid. The findings are discussed in relation to the assumed pathway for side chain cleavage in cholic acid biosynthesis.
Substrate specificity of flax hydroperoxide isomerase
Authors: Feng Paul , Zimmerman Don C. 
Published: November 2006

AbstractIncubations of the 13‐ and 9‐hydroperoxides of linolenic acid with a flax acetone powder extract containing hydroperoxide isomerase resulted in the formation of 13‐hydroxy‐12‐oxo‐cis‐9,15‐octadecadienoic acid and 9‐hydroxy‐10‐oxo‐cis‐12,15‐octadecadienoic acid, respectively. The rate of formation of product from 13‐hydroperoxy linolenic acid was 36 times that from 9‐hydroperoxy linolenic acid. Analogous results were obtained with the 13‐ and 9‐hydroperoxides of linoleic acid. The results demonstrated the substrate specificity of flax hydroperoxide isomerase.
Antioxidant stoichiometry and the oxidative fate of vitamin E in peroxyl radical scavenging reactions
Authors: Liebler Daniel C. , Burr Jeanne A. 
Published: November 2006

AbstractOxidation ofR,R,R‐α‐tocopherol (vitamin E; TH) by peroxyl radicals generated from the azo initiator azobis(2,4‐dimethylvaleronitrile) in acetonitrile, hexane, or in phospholipid liposomes yields 8a‐(alkyldioxy)tocopherone adducts, 8a‐(hydroxy)tocopherone, and their hydrolysis product α‐tocopherolquinone TH oxidation also yields 4a,5‐epoxy‐ and 7,8‐epoxy‐8a‐(hydroperoxy)tocopherones and their respective hydrolysis products 2,3‐epoxy‐α‐tocopherolquinone and 5,6‐epoxy‐α‐tocopherolquinone. Previous work indicates that the distribution of TH oxidation products varies with reaction environment. We investigated the dependence of antioxidant stoichiometry on TH oxidation product distribution for reactions in hexane, acetonitrile, and in phosphatidylcholine liposomes. Yields of 8a‐substituted tocopherones were highest in hexane and lowest in phosphatidylcholine liposomes. In contrast, yields of epoxide products were highest in the liposome system and lowest in hexane. Yields of α‐tocopherolquinone were similar in all three systems. Antioxidant stoichiometry, measured by the inhibited autoxidation method, was approximately 2.0 peroxyl radicals trapped per TH consumed in acetonitrile and in liposomes. In hexane, a slightly larger stoichiometric factor of approximately 2.5 was measured. This may, in part, reflect the generation of more reactive alkoxyl radicals in hexane. The reaction environment thus markedly affects the balance between competing TH oxidation pathways but produces comparatively little effect on antioxidant stoichiometry. These results imply that competing reaction pathways contribute similarly to the antioxidant chemistry of TH.
Monohydroperoxides of linoleic acid in endoplasmic lipids of rats exposed to tetrachloromethane
Authors: Frank Hartmut , Wiegand Manfred , Strecker Manfred , Thiel Dietmar 
Published: November 2006

AbstractAn accurate method for the quantitative determination of hydroperoxy and hydroxy fatty acids in liver microsomes is presented which involves the use of18O‐labeled internal standards. The method is employed for the determination of hydroperoxides in rat liver microsomes after aerobic incubation with Fe2+/ADP and in microsomes from animals exposed to 75 mg tetrachloromethane/kg body weight. The amounts found after artificial microsomal “lipid peroxidation” are almost two orders of magnitude larger than those in microsomes from tetrachloromethaneexposed animals.
The differential effect of polymyxin B1 on guinea pig lung mitochondrial and microsomal glycerophosphate acyltransferase
Authors: Das Salil K. , Haldar Dipak 
Published: November 2006

AbstractThe activities of guinea pig lung mitochondrial and microsomal glycerophosphate acyltransferase differed in sensitivity to polymyxin B1. At an antibiotic concentration of 1 mg/ml, the mitochondrial enzyme activity was stimulated twofold, but the microsomal enzyme activity was completely inhibited. Furthermore, the mitochondrial enzyme activity was stimulated by polymyxin B1 without the addition of exogenous acyl‐CoA. Additional experiments ruled out the possibility of polymyxin B1 acting as a substrate for the mitochondrial acyltransferase. These results suggest either that the polymyxin B1 sensitivity of mitochondrial and microsomal glycerophosphate acyltransferase is different or that their accessibility to substrates is different because the two isoenzymes are located differently in the different phospholipid microenvironment of the membranes.
Effect of feeding protected lipids on fatty acid synthesis in ovine tissues
Authors: Hood R. L. , Cook L. J. , Mills S. C. , Scott T. W. 
Published: November 2006

AbstractThe effects of including protected lipid supplements in the sheep diet have been studied by measuring the incorporation of [1‐14C] acetate into tissue fatty acids in vivo and in vitro. Supplementing the diet with protected lipid significantly (P<0.05) depressed lipogenesis in adipose tissue both in vivo and in vitro. However, when protected lipids of different fatty acid composition were given to lambs, the protected safflower oil supplement containing high levels of linoleic acid was the only treatment to cause a significant (P<0.05) depression in fatty acid synthesis in adipose tissue, the major site of lipogenesis in the sheep. Larger adipose cells in the lipid‐supplemented sheep indicate that these sheep were fatter than those receiving the basal diet. Therefore, supplemented wethers deposited more fat than sheep receiving the basal diet and this fat was derived from the supplement rather than from de novo synthesis.
Effect of different fatty acids on triacylglycerol secretion in isolated rat hepatocytes
Authors: Åkesson B. 
Published: November 2006

AbstractLipoprotein triacylglycerol secretion was studied in isolated rat hepatocytes incubated with different albumin‐bound fatty acids and labeled glycerol. The release of labeled triacylglycerol was stimulated more by unsaturated fatty acids than by saturated ones. When lipoprotein secretion was related to cell triacylglycerol synthesis, an effect of unsaturation was no longer observed. Instead the secretion rate, expressed in this manner, increased with increasing fatty acid chain length. For the first time, the secretion of molecular species of triacylglycerol has been studied. The distribution of labeled glycerol among different species was the same in the cells and in the secreted product, indicating that different triacylglycerols were secreted without selectivity. It is concluded that the fatty acid structure influences lipoprotein triacylglycerol secretion and it is emphasized that the effects observed depend on the method of quantitation of the secretion rate.
Horse erythrocyte gangliosides: Preparation of the major hematoside NeuNG1‐Lac‐Cer
Authors: Maget‐Dana R. , Michalski J. C. 
Published: November 2006

AbstractA simple method for the isolation of hematoside NeuNG1‐Lac‐Cer from horse erythrocytes is described. An aliquot of the crude ganglioside fraction was labeled by tritiated sodium borohydride after mild periodate oxidation. The compounds obtained were used as radioactive tracers in column chromatography. Gangliosides were applied onto a silicic acid column and eluted stepwise by solvents of steadily increasing polarity. The major ganglioside, NeuNG1‐Lac‐Cer, was eluted in a high yield by the solvent mixture chloroform/methanol/water (60∶35∶8, v/v/v).
Regulation of lung surfactant cholesterol metabolism by serum lipoproteins
Authors: Hass Michael A. , Longmore William J. 
Published: November 2006

AbstractThe isolated perfused rat lung was used as an experimental model in the study of the lipoprotein regulation of surfactant cholesterol metabolism. Addition of low density lipoproteins (LDL) to the perfusion medium at a cholesterol concentration of 0.5 mM had no inhibitory effect on [1‐14C]‐acetate incorporation into cholesterol of either the surfactant or residual fractions. Increasing the concentration of cholesterol in the medium to 2.5 mM resulted in significant inhibition of incorporation into cholesterol of both fractions. A similar inhibition resulted when lungs were perfused with 2.5 mM cholesterol in the form of high density lipoproteins (HDL). No inhibition of fatty acid synthesis, measured as incorporation into cholesteryl esters, was observed. The rate of uptake by perfused lung of cholesterol from both high and low density lipoproteins was similar. Competitive binding studies with125I‐labeled lipoproteins indicated the existence of lung receptors for both classes of lipoprotein. The rate of uptake of the apoprotein moiety of low density lipoproteins was significantly greater than that of high density lipoproteins. These data suggest that lung cholesterol metabolism may be subject to regulation by both low and high density serum lipoproteins.
Cyclopropene fatty acids in some Malaysian edible seeds and nuts: I. Durian (Durio zibethinus, Murr.)
Authors: Berry Shiv K. 
Published: November 2006

AbstractThe aril and seeds of the fruit Durian (Durio zibethinus, Murr.) were examined for their protein content and fatty acid composition by gas liquid chromatography (GLC). The values (area percentage) for fatty acids as methyl esters were: aril=14∶0 (0.91%); 16∶0 (34.13%); 16∶1 (7.10%); 18∶0 (1.21%); 18∶1 (42.14%); 18∶2 (7.85%) and 18∶3 plus 20∶0 (5.69%), Seeds=14∶0 (0.12%); 16∶0 (12.20%); 16∶1 (1.15%); 18∶0 (1.42%); 18∶1 (8.42%); 18∶2 (6.50%); dihydrosterculic acid (2.52%); 18∶3 plus 20∶0 (11.30%); malvalic acid (15.72%); sterculic acid (38.53%) and 22∶0 (1.21%). The germ oil contained the highest amount of sterculic acid. The cooking temperatures employed reduced the malvalic and sterculic acid contents in seeds only by ca. 22% and 19%, respectively.
Product specificity of rice germ lipoxygenase
Authors: Yamamoto A. , Fujii Y. , Yasumoto K. , Mitsuda H. 
Published: November 2006

AbstractIncubation of linoleic acid with partially purified lipoxygenase from rice germ yielded a ratio of 9‐to 13‐hydroperoxides of linoleic acid of 97∶3 as measured by high performance liquid chromatography. Under similar conditions, hematin gave the 9‐ to 13‐hydroperoxides at a ratio of 51∶49, and soybean lipoxygenase‐a at 9∶91. Infrared spectral analysis revealedcis‐trans configuration to predominate in the reaction products with the rice germ enzyme as was with the soybean enzyme.
Interaction of porcine pancreatic colipase with a nonionic detergent, triton X‐100: Spectrophotometric studies
Authors: Canioni Paul , Julien Robert , Rathelot Joëlle , Sarda Louis 
Published: November 2006

AbstractStrong perturbation of the ultraviolet spectrum of the tyrosines of porcine pancreatic colipase A is observed in the presence of Triton X‐100 at concentration above the critical micellar concentration. Spectrophotometric titration of the phenolic groups of the protein shows that the apparent pKa value for two tyrosines is about 10.3, while the third tyrosine has a higher pKa value above 11.6. This residue is still protonated at pH 13 in the presence of Triton X‐100. All perturbations induced by the nonionic detergent can be interpreted as resulting from interactions between colipase and Triton X‐100 molecules at a hydrophobic site of the protein that includes the tyrosine residues. Results obtained in studies with Triton X‐100 are similar to those already reported by Sari et al. (Eur. J. Biochem. 58∶561 (1975) on the interaction of colipase with taurodeoxycholate. It is likely that the binding of both types of detergent occurs at the same specific site on the protein molecule. Data presented in this communication give further support to the hypothesis that a hydrophobic domain (residues 49–57), including all three tyrosines of the colipase molecule, participate to the well characterized interaction of the lipase cofactor with triglycerides at lipid‐water interfaces.
Occurrence of 24(E)‐ethylidene sterols in two solanaceae seed oils and rice bran oil
Authors: Itoh Toshihiro , Sakurai Suguru , Tamura Toshitake , Matsumoto Taro 
Published: November 2006

AbstractThe occurrence of two 24 (E)‐ethylidene sterols, fucosterol and 28‐isocitrostadienol, in the unsaponifiable matters of two Solanaceae seed oils fromDatura stramonium andCapsicum annuum, and rice bran oil from the seeds ofOryza sativa (Gramineae) was demonstrated by their isolation or by gas liquid chromatography. AlthoughZ‐isomers of the above two 24‐ethylidene sterols, 28‐isofucosterol and citrostadienol, are a frequent occurrence in higher plant materials including some Solanaceae seed oils and rice bran oil, the report might be the second instance of the unambiguous demonstration of the occurrence of the 24(E)‐ethylidene sterols in higher plants.
Desaturation of isomericcis 18∶1 acids
Authors: Mahfouz M. , Holman R. T. 
Published: November 2006

AbstractThe desaturation of positionalcis 18∶1 isomers (Δ4 through Δ11) was studied, using essential fatty acid deficient rat liver microsomes. Thecis Δ4, Δ5, Δ6 and Δ7 isomers were not desaturated. Thecis Δ10 and Δ11 isomers were desaturated at a very low rate. The maximum desaturation was obtained for Δ8 and Δ9 isomers. Thecis Δ8 and Δ11 isomers were desaturated by Δ5 desaturase; thecis Δ9 isomer was desaturated by Δ6 desaturase; and thecis Δ10 isomer was desaturated to Δ7,10 and 5,10–18∶2 acids.
Relationship between lipids in plasma and skin secretions of neonatal calf with particular reference to linoleic acid
Authors: Noble R. C. , Crouchman M. L. , Jenkinson D. Mcewan , Moore J. H. 
Published: November 2006

AbstractA study has been made on the lipid composition of the skin secretions and plasma of the neonatal calf. A significant proportion of the skin surface lipids was comprised of triglycerides. Saturated fatty acids comprised the major proportion of the fatty acids of the skin surface triglycerides at birth. Immediately after birth, the pooportion of the saturated fatty acids decreased, and there was a concomittant increase in the proportion of 18∶1. Some 3–4 weeks after birth, the proportion of 18∶2 Δcis‐9, cis‐12 in the skin surface triglycerides increased to ca. 14%, and there was a decrease in the proportion of 18∶1. The 18∶2 was shown to be confined almost entirely to the 2 position of the triglycerides. During the first 5 weeks after birth, the concentrations of the cholesteryl esters and phospholipids in the plasma increased markedly and were accompanied by a rapid increase in the proportion of 18∶2 within these 2 fractions. The results are discussed in relation to the known role of 18∶2 in the metabolism of biological systems.