bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modulation of prostaglandin H synthase activity by conjugated linoleic acid (CLA) and specific CLA isomers
Authors: Bulgarella Jennifer A. , Patton David , Bull Arthur W. 
Published: November 2006

AbstractConjugated linoleic acid (CLA) has been shown to inhibit tumorigenesis in animal models and is cytostatic to numerous cell lines in vitro. However, the mechanism of action is unknown. In the current study, we determined the effects of CLA and specific isomers of CLA on the rate of oxygenation of arachidonic acid by prostaglandin H synthase (PGHS) in ram seminal vesicle microsomes. The enzyme was incubated with 0.1 to 100 μM CLA or specific isomers of CLA for 2 min prior to the addition of 44 to 176 μM arachidonate. The isomers tested were 9(E),11(E) CLA; 9(Z),11(E) CLA; 9(Z),11(Z) CLA, and 10(E),12(Z) CLA. For a positive inhibitor control, flurbiprofen was used at 0.75 to 2.50 μM. Enzyme activity was assessed by measuring the rate of oxygen consumption. Inclusion of CLA or specific isomers of CLA in the incubation mixtures inhibits PGHS. The efficacy differs for each isomer, with the 9(Z),11(E) CLA isomer being the most effective and the 9(Z),11(Z) CLA isomer being the least effective inhibitor among the four CLA isomers tested. The Ki values obtained by Dixon replots range from 18.7 μM for the most effective isomer, 9(Z),11(Z) CLA, to 105.3 μM for the least effective isomer, 9(Z),11(Z) CLA. The Ki value for flurbiprofen with ram seminal vesicle microsomes was 0.33 μM. As the concentration of arachidonate was increased, the CLA‐dependent inhibition of PGHS decreased, suggesting competitive inhibition. The results of this study demonstrate the potential of CLA and specific isomers of CLA to modulate prostaglandin biosynthesis.
Hen egg yolk and white contain high amounts of lysophosphatidic acids, growth factor‐like lipids: Distinct Molecular species compositions
Authors: Nakane Shinji , Tokumura Akira , Waku Keizo , Sugiura Takayuki 
Published: November 2006

AbstractHen egg yolk and white were found to contain high amounts of lysophosphatidic acid (acyl LPA) in addition to small amounts of lysoplasmanic acid (alkyl LPA). The levels of acyl LPA in hen egg yolk (44.23 nmol/g tissue) and while (8.81 nmol/g tissue) were on the same order as or higher than the levels of acyl LPA known to be required to elicit biological responses in various animal tissues. Noticeably, there is a marked difference between the fatty acid composition of egg yolk acyl LPA and of egg white acyl LPA; egg yolk acyl LPA predominantly contains saturated fatty acids as the acyl moiety, whereas egg white acyl LPA primarily contains polyunsaturated fatty acids. We found that the level of acyl LPA, especially polyun‐saturated fatty acid‐containing acyl LPA, in egg white was augmented markedly during the incubation at 37°C, while there was no change in egg yolk. We confirmed that egg white contains both the substrate, i.e., polyunsaturated fatty acid‐containing lysophosphatidylcholine (LPC), and the enzyme activity catalyzing the hydrolysis of polyunsaturated fatty acid‐containing LPC to the corresponding acyl LPA. Egg yolk LPA and egg white LPA may play separate physiological roles in the development, differentiation, and growth of embryos.
Studies on effects of dietary fatty acids as related to their position on triglycerides
Authors: Hunter J. Edward 
Published: November 2006

AbstractThis article reviews published literature on how the stereospecific structure of dietary triglycerides may affect lipid metabolism in humans. Animal studies have shown enhanced absorption of fatty acids in the sn‐2 position of dietary triglycerides. Increasing the level of the saturated fatty acid palmitic acid in the sn‐2 position (e.g., by interesterification of the fat to randomize the positions of the fatty acids along the glycerol backbone) has been shown in rabbits to increase the atherogenic potential of the fat without impacting levels of blood lipids and lipoproteins. In contrast, enhancing the level of stearic acid in the sn‐2 position has not been found to affect either atherogenic potential or levels of blood lipids and lipoproteins in rabbit. Fatty acids other than palmitic and stearic have not been studied systematically with respect to possible positional effects. A limited number of human studies have shown no significant effects of interesterified fats on blood lipid parameters. However, it is unknown whether modifying the stereospecific structure of dietary triglycerides would affect atherogenicity or other long‐term health conditions in humans. It is possible that incorporation of palmitic acid into the sn‐2 position of milk fat is beneficial to the human infant (as a source of energy for growth and development) but not to human adults. Additional research is needed to determine whether processes like interesterification, which can be used to alter physical parameters of dietary fats (e.g., melting characteristics), may result in favorable or unfavorable long‐term effects in humans.
Fatty acid content of plasma lipids and erythrocyte phospholipids are altered following burn injury
Authors: Pratt Vera C. , Tredget Edward E. , Clandinin M. Thomas , Field Catherine J. 
Published: November 2006

AbstractThe objective of this study was to examine compositional and quantitative changes in fatty acids of plasma components and red blood cell phospholipids (PL) immediately following and during recovery from burn injury. Subjects (n=10) with >10% total body surface area burn had blood drawn at specific timepoints (0 to >50 d) following burn injury. Fatty acid composition of red blood cell PL and plasma PL, cholesteryl esters (CE), and triglycerides was determined using gas‐liquid chromatography after separating each fraction from extracted lipids by thin‐layer chromatography. Total plasma PL and CE in burn patients were lower than in healthy control subjects with reduced 20∶4n−6, n−6, and n−3 fatty acids and higher levels of monounsaturated and saturated fatty acids early after burn. CE levels remained half that of healthy control values up to 50 d post‐burn. Red blood cell PL had decreased 20∶4n−6 content and profiles similar to that of an essential fatty acid deficiency early after burn. These results suggest an impairment in lipoprotein and polyunsaturated fatty acid metabolism in the early post‐burn period. Lower levels of 20∶4n−6 and n−3 fatty acids in every plasma fraction suggest increased use of these fatty acids for wound healing and immune function following burn injury. Further work is needed to determine the ability of burn patients to utilize essential fatty acids in order to design nutritional intervention that promotes wound healing and immunological functions consistent with recovery in these patients.
Regulation of intestinal apolipoprotein A‐I synthesis by dietary phosphatidylcholine in newborn swine
Authors: Wang Heng , Du Jianhui , Lu Song , Yao Ying , Hunter Felicia , Black Dennis D. 
Published: November 2006

AbstractPhospholipid (PL) from both dietary sources and biliary secretions may be important in the regulation of intestinal apolipoprotein (apo) synthesis. We previously demonstrated the up‐regulation of apo A‐I secretion by phosphatidylcholine (PC) in a newborn piglet intestinal epithelial cell line. We hypothesized that dietary PC increases small intestinal apo A‐I synthesis in vivo in the newborn piglet. Two‐day‐old female swine were fed by gavage for 48 h. Diets consisted of a formula containing 51% of calories as triacylglycerol providing 180 kcal/kg/24 h. The experimental group (+PC, n=7) received 1 g/L added soybean PC, and the control group (−PC, n=7) received no added PC. At the end of the study period, jejunal apo A‐I, B, and A‐IV synthesis was measured, and apo A‐I mRNA levels were quantitated. Jejunal mucosal PI content and serum lipids and apo B and A‐I levels were measured. Jejunal apo A‐I synthesis was almost twice as high in the +PC group as compared to the −PC group with no difference in apo A‐I mRNA levels. Jejunal content of PL was higher in the +PC group than in the −PC group. There were no differences in jejunal apo B and A‐IV synthesis or serum levels of lipids and apo‐lipoproteins between the two groups. Dietary PC supplementation in newborn swine up‐regulated jejunal apo A‐I synthesis. Apo A‐IV synthesis, which is sensitive to fatty acid flux, was not significantly increased, which suggests a specific effect of PC on apo A‐I synthesis. Lumenal PC may be important in the regulation of intestinal apo A‐I synthesis in the neonate.
Studies of phospholipid metabolism, proliferation, and secretion of stably transfected insulinoma cells that overexpress group VIA phospholipase A2
Authors: Ma Zhongmin , Bohrer Alan , Wohltmann Mary , Ramanadham Sasanka , Hsu Fong‐Fu , Turk John 
Published: November 2006

AbstractA cytosolic 84 kDa Group VIA phospholipase A2 (iPLA2β) that does not require Ca2+ for catalysis was cloned from Chinese hamster ovary (CHO) cells, murine P388D1 cells, pancreatic islet β‐cells, and other sources. Proposed iPLA2β functions include participation in phosphatidylcholine (PC) homeostasis by degrading excess PC generated in CHO cells that overexpress CTP:phosphocholine cytidylyltransferase (CT), which catalyzes the rate‐limiting step in PC biosynthesis; participation in biosynthesis of arachidonate‐containing PC species in P388D1 cells by generating lysophosphatidylcholine (IPC) acceptors for arachidonate incorporation; and participation in signaling events in insulin secretion from islet β‐cells. To further examine iPLA2β functions in β‐cells, we prepared stably transfected INS‐1 insulinoma cell lines that overexpress iPLA2β activity eightfold compared to parental INS‐1 cells or to INS‐1 cells transfected with an empty retroviral vector that did not contain iPIA2β cDNA. The iPLA2β‐overexpressing cells exhibit a twofold increase in CT activity compared to parental cells but little change in rates of [3H] choline incorporation into or disappearance from PC. Electrospray ionization (ESI) tandem mass spectrometric measurements indicate that iPLA2β‐overexpressing cells have 1.5‐fold higher LPC levels than parental INS‐1 cells but do not exhibit increased rates of [3H]arachidonate incorporation into phospholipids, and incorporation is unaffected by a bromoenol lactone (BEL) suicide substrate inhibitor of iPLA2β. The rate of appearance of arachidonate‐containing phosphatidylethanolamine species visualized by ESI mass spectrometry is also similar in iPLA2β‐overexpressing and parental INS‐1 cells incubated with supplemental arachidonic acid, and this process is unaffected by BEL. Compared to parental INS‐1 cells, iPLA2β‐overexpressing cells proliferate more rapidly and exhibit amplified insulin secretory responses to a protein kinase C‐activating phorbol ester, glucose, and a cAMP analog. These findings suggest that iPLA2β plays a signaling role in β‐cells that differs from housekeeping functions in PC biosynthesis and degradation in P388D1 and CHO cells.
Metabolism of an oxysterol, 7‐ketocholesterol, by sterol 27‐hydroxylase in hepG2 cells
Authors: Lyons Malcolm A. , Brown Andrew J. 
Published: November 2006

Abstract7‐Ketocholesterol (7K) is a quantitatively important oxysterol in both atherosclerotic lesions and macrophage foam cells. We reported recently that radiolabeled 7K delivered to rodents in a modified lipoprotein or chylomicron remnantlike emulsion, both cleared predominantly by the liver, was rapidly excreted into the intestine as water‐soluble products, presumably bile acids. Herein, we aimed to elucidate the early or initial reactions in 7K metabolism. The hypothesis was tested that sterol 27‐hydroxylase, a mitochondrial cytochrome P450 and the first enzyme of the acidic bile acid pathway, is responsible for the initial metabolism of 7K by HepG2 cells, a human hepatoblastoma cell‐line. The 27‐hydroxylated product of 7K (27OH‐7K) was shown to be the initial, lipid‐soluble product of 7K metabolism. It was produced in mitochondrial incubations and whole cells and was readily released into the media from cells. Intact cells generated metabolites of 7K that had undergone conversion from lipid‐soluble precusors to water‐soluble products rapidly and extensively. Their production was ablated with cyclosporin A, a sterol 27‐hydroxylase inhibitor. Furthermore, we demonstrated the effectiveness of two novel selective inhibitors of this enzyme, GW273297X and GI268267X. These inhibitors also ablated the production of water‐soluble products by cells; and the inhibitor of choice, GW273297X, decreased the production of 27OH‐7K in mitochondrial preparations. This is the first study to demonstrate that sterol 27‐hydroxylase plays an important role in the metabolism of oxysterols such as 7K in liver cells.
Modeling of α‐tocopherol loss and oxidation products formed during thermoxidation in triolein and tripalmitin mixtures
Authors: Verleyen T. , Kamal‐Eldin A. , Dobarganes C. , Verhe R. , Dewettinck K. , Huyghebaert A. 
Published: November 2006

AbstractThe degradation of α‐tocopherol and the formation of α‐tocopherol and triacylglycerol oxidation products at high temperatures (150–250°C) over a heating period (0–4h) for a model system ranging between triolein and tripalmitin were modeled by use of an experimental design. The oxidation products of α‐tocopherol formed under these conditions were α‐tocopherolquinone (1.4–7.7%) and epoxy‐α‐tocopherolquinones (4.3–34.8%). The results indicate a very high susceptibility of α‐tocopherol to capture peroxyl radicals upon oxidation, leading to the formation of polar tocopherol oxidation products. Both α‐tocopherolquinone and epoxy‐α‐tocopherolquinones were not stable upon prolonged heating and were further degraded to other unknown oxidation products. The kinetics of α‐tocopherol oxidation were significantly influenced by the triolein/tripalmitin ratio. By increasing the level of triacylglycerol unsaturation the rate of α‐tocopherol recovery after heating increased significantly from 2.2 to 44.2% whereas in the meantime triacylglycerol polymerization increased from 0 to 3.7%.
Positional distribution of highly unsaturated fatty acids in triacyl‐sn‐glycerols of Artemia nauplii enriched with docosahexaenoic acid ethyl ester
Authors: Ando Yasuhiro , Oomi Yoshiaki 
Published: November 2006

AbstractThis paper presents the positional distribution of fatty acids in triacyl‐sn‐glycerols (TAG) of Artemia nauplii used in aquaculture as a live food for marine fish larvae. The nauplii were enriched with docosahexaenoic acid (DHA) ethyl ester (EE) in the form of gelatin‐acacia microcapsules for 4, 18, and 24 h. TAG of the initial, enriched, and unenriched Artemia nauplii were subjected to stereospecific analysis. A remarkable increase of DHA content in the enriched Artemia TAG confirmed the view that DHA‐EE is effectively assimilated and incorporated into the TAG fraction of Artemia nauplii. TAG of the nauplii enriched with 25 mg/L of DHA‐EE contained DHA at concentrations of 5.9–6.8, 4.3–6.0, and 14.3–22.3 mol% in the sn‐1, sn‐2, and sn‐3 positions, respectively. When the nauplii were enriched with 100 mg/L of DHA‐EE, proportions of DHA in the sn‐1, sn‐2, and sn‐3 positions were 5.2–8.6, 3.9–6.0, and 12.2–25.4 mol%, respectively. In all of the enriched Artemia, DHA was preferentially located in the sn‐3 position followed in sequence by the sn‐1 and sn‐2 positions. The lower content of DHA in the sn‐1 and sn‐2 positions was consistent with low content of this acid in 1,2‐diacyl‐sn‐glycerophospholipids. When fish larvae are reared on Artemia nauplii enriched with LL‐type DHA oil, the larvae feed on DHA esterified in TAG with a positional distribution pattern similar to that of marine mammals (sn‐3≫sn‐1>sn‐2) rather than that of fish or marine invertebrates (sn‐2≫sn‐3>sn‐1).
Determination of stereochemical configuration of the glycerol moieties in glycoglycerolipids by chiral phase high‐performance liquid chromatography
Authors: Takahashi Yoshinori , Itabashi Yutaka , Suzuki Minoru , Kuksis Arnis 
Published: November 2006

AbstractThis study reports a simple and sensitive method for determining the absolute configuration of the glycerol moieties in glycoglycerolipids. The method is based on chiral phase high‐performance liquid chromatography (HPLC) separations of enantiomeric di‐ and monoacylglycerols released from glycosyldi‐ and monoacylglycerols, respectively, by periodate oxidation followed by hydrazinolysis. The released di‐ and monoacylglycerols were chromatographed as their 3,5‐dinitrophenylurethane (3,5‐DNPU), and bis(3,5‐DNPU) derivatives, respectively. The derivatives were separated on two chiral phases of opposite configuration, (R)‐and (S)‐1‐(1‐naphthyl)ethylamine polymers for diacylglycerols and N‐(R)‐1‐(1‐naphthyl)ethylaminocarbonyl‐(S)‐valine and N‐(S)‐1‐(1‐naphyl)ethylamino‐carbonyl‐(R)‐valine for monoacylglycerols. Clear enantiomer separations, which permit the assignment of the glycerol configuration, were achieved for sn‐1,2(2,3)‐dicyl‐ and sn‐1(3)‐monoacylglycerols generated from linseed oil triacylglycerols by partial Grignard degradation on all the chiral stationary phases employed. Using the method, we have determined the glycerol configuration in the glycosyl‐diacylglycerols (monogalactosyl‐, digalactosyl‐, and sulfquinovo‐syldiacylglycerols) and glycosylmonoacylglycerols (monogalactosyl‐, digalactosyl‐, and sulfoquinovosylmonoacylglycerols) isolated from spinach leaves and the coralline red alga Corallina pilulifera. The results clearly showed that the glycerol moieties in all the glycoglycerolipids examined have S‐configuration sn‐1,2‐diacyl‐ and sn‐1‐monoacylglycerols). The new method demonstrates that chiral phase HPLC provides unambiguous information on the configuration of the glycerol backbone in natural glycosyldi‐ and monoacylglycerols, and that the two‐step liberation of the free acylglycerols does not compromise glycerol chirality.
Genomic and functional characterization of polyunsaturated fatty acid biosynthesis in Caenorhabditis elegans
Authors: Napier Johnathan A. , Michaelson Louise V. 
Published: November 2006

AbstractThe biosynthetic pathway for polyunsaturated fatty acids in the model animal Caenorhabditis elegans was examined in the context of the completed genome sequence. The genomic organization and location of seven desaturase genes and one elongase activity, all previously identified by functional characterization, were elucidated. A pathway for the biosynthesis of polyunsaturated fatty acids in C. elegans was proposed based on these genes. The role of gene duplication in enzyme evolution and proliferation is discussed.
Conjugated linoleic acid supplementation in humans: Effects on fatty acid and glycerol kinetics
Authors: Zambell Kirsten L. , Horn William F. , Keim Nancy L. 
Published: November 2006

AbstractRecent studies with mouse adipocytes have shown that dietary conjugated linoleic acid (CLA) may reduce body fat by increasing lipolysis. The present study examined the effect of CLA supplementation on fatty acid and glycerol kinetics in six healthy, adult women who were participating in a controlled metabolic ward study. These women were fed six CLA capsules per day (3.9 g/d) for 64 d following a baseline period of 30 d. The subjects were confined to a metabolic suite for the entire 94‐d study, where diet and activity were controlled and held constant. The rate of appearance (Ra) of glycerol, which indicates lipolytic rates, was similar at baseline and after 4 wk of CLA supplementation at rest (1.87±0.21 and 2.00±0.39 μmol/kg/min, respectively) and during exercise (7.12±0.74 and 6.40±0.99 μmol/kg/min, respectively). Likewise, the Ra of free fatty acids (FFA) was not significantly different after 4 wk of dietary CLA at rest (2.72±0.06 and 2.74±0.12 μmol/kg/min, respectively) or during exercise (6.99±0.40 and 5.88±0.29 μmol/kg/min, respectively). CLA supplementation also had no effect on the percentage of FFA released from lipolysis that were re‐esterified. The apparent rate of FFA re‐esterification was 65.2±4.2% at rest and 32.1±3.44% during exercise. Four weeks of CLA supplementation had no significant effect on fatty acid or glycerol metabolism in healthy, weight‐stable, adult women.
Conjugated linoleic acid supplementation in humans—metabolic effects
Authors: Smedman Annika , Vessby Bengt 
Published: November 2006

AbstractSupplementation with conjugated linoleic acid (CLA) induces a number of physiological effects in experimental animals, including reduced body fat content, decreased aortic lipid deposition, and improved serum lipid profile. Controlled trials on the effects of CLA in humans have hitherto been scarce. The aim of this study was to evaluate the effects of supplementation with CLA in healthy humans on anthropometric and metabolic variables and on the fatty acid composition of serum lipids and thrombocytes. Fifty‐three healthy men and women, aged 23–63 yr, were randomly assigned to supplementation with CLA (4.2 g/d) or the same amount of olive oil during 12 wk in a double‐blind fashion. The proportion of body fat decreased (−3.8%, P<0.001) in the CLA‐treated group, with a significant difference from the control group (P=0.050). Body weight, body mass index, and sagittal abdominal diameter were unchanged. There were no major differences between the groups in serum lipoproteins, nonesterified fatty acids, plasma insulin, blood glucose, or plasminogen activator inhibitor 1 (PAI‐1). In the CLA group the proportions of stearic, docosatetraenoic, and docosapentaenoic acids increased in serum lipids and thrombocytes, while proportions of palmitic, oleic, and dihomoγ‐linolenic acids decreased, causing a decrease of the estimated Δ‐6 and Δ‐9 and an increase in the Δ‐5 desaturase activities. These results suggest that supplementation with CLA may reduce the proportion of body fat in humans and that CLA affects fatty acid metabolism. No effects on body weight, serum lipids, glucose metabolism, or PAI‐1 were seen.