bluuebunny/crossref_metadata_2025_split huggingface dataset:
Alteration of hepatic phospholipids in rats and mice by feeding di‐(2‐ethylhexyl)adipate and di‐(2‐ethylhexyl)phthalate
Authors: Yanagita Teruyoshi , Satoh Mikinobu , Nomura Hisashi , Enomoto Noriyuki , Sugano Michihiro 
Published: November 2006

AbstractEffects of di‐(2‐ethylhexyl)adipate (DOA) and di‐(2‐ethylhexyl)phthalate (DEHP), plasticizers for polyvinylchloride products, on concentrations and compositions of hepatic phospholipids were studied in rats. When administered to rats at a 2% level for 2 wk, both DOA and DEHP caused a hepatomegaly, an increase in hepatic phospholipids and a decrease in the ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE). In the comparable study with mice, the alkyl moiety of DOA was found to be responsible for these alterations. DOA and DEHP specifically altered fatty acid compositions of PC and PE: there was an increase in oleic and palmitic acids and a decrease in stearic and docosahexaenoic acids in PC and an increase in arachidonic acid at the expense of docosahexaenoic acid in PE. In addition, DOA caused an increase in the trienoic and tetraenoic molecular species in PC and an increase in the 1‐palmitoyl‐2‐arachidonyl (16∶0//20∶4) species in PE. Thus, the effects of DOA on the lipid dynamics resembled those observed with DEHP, although the magnitude was slightly moderated.
Derivatization of keto fatty acids, X: Synthesis of thiazanones
Authors: Khan Amjadullah , Husain S. Rafat , Ahmad F. , Siddiqui M. S. , Pimlott W. 
Published: November 2006

AbstractThe synthesis of alkyl chain‐substituted thiazanones from oxo fatty esters and a long chain aldehyde is reported. Four oxo compounds—methyl 10‐oxoundecanoate, methyl 9‐oxooctadecanoate, methyl 9,10‐dioxooctadecanoate and octadecanal—were allowed to react with β‐mercaptopropionic acid in the presence of ammonium carbonate in benzene to give the corresponding 4‐m‐thiazanones in high yields. The structures of these compounds were confirmed by combustion and spectral data.
Effect of cold environment on hepatic microsomal Δ6 and Δ9 desaturase activity of male rats
Authors: Losada Ana Ves , Peluffo Raul O. 
Published: November 2006

AbstractMale rats maintained at 24 C and then shifted to 5 C for 5 days increased food intake and decreased in growth rate and food conversion. No modification was observed in Δ6 desaturase activity, while Δ9 desaturase activity decreased after this period of time. These results were confirmed by liver microsomal and mitochondrial fatty acid composition. The phospholipid composition of liver microsomes was unaltered, whereas in mitochondria, phosphatidylcholine and sphingomyelin decreased and phosphatidylethanolamine increased due to the cold environment. The influence of food intake and weight changes on fatty acid metabolism was studied using (i) rats maintained at 5 C with restricted food intake to match the food intake of those kept at 24 C with food ad libitum and (ii) rats maintained at 24 C whose food intake was also restricted so that their growth rate would be the same as that of rats maintained at 5 C with food ad libitum, respectively. These results indicate that the negative metabolic balance state of these cold conditions is not an active factor modifier of Δ6 desaturase activity, whereas it decreases Δ9 desaturase activity, reflecting the lipogenic characteristics of the latter enzyme.
Rapid separations of diacyl‐ and dialkylglycerol enantiomers by high performance liquid chromatography on a chiral stationary phase
Authors: Takagi Toru , Itabashi Tutaka 
Published: November 2006

AbstractRapid and practical separations of 1,2‐and 2,3‐diacyl‐and dialkyl‐sn‐glycerol enantimers as their 3,5‐dinitrophenylurethane derivatives were carried out by normal‐phase high performance liquid chromatography on a chiral stationary phase, N‐(R)‐1‐(α‐naphthyl)ethylaminocarbonyl‐(S)‐valine chemically bonded to γ‐aminopropyl silanized silica. Complete separations of the racemates into enantiomers were achieved for both of the diacyl‐and dialkylglycerols within 10 min using a stainless steel column (25 cm long) packed with the 5‐μ particles, an isocratic elution with a mixture of hexane/ethylene dichloride/ethanol as a mobile phase and a UV detector. Thesn‐1,2‐enantiomers were eluted ahead of the correspondingsn‐2,3‐enantiomers. Satisfactory separation of thesn‐1,3‐diacylglycerols from the corresponding enantiomers and the separation of the homologues differing in acyl and alkyl groups were also observed. The formations of hydrogen bonding and charge transfer complex between the urethane derivatives and the stationary phase may contribute to the enantiomer separations.
Effect of hypothyroidism on the lipid composition of rat plasma and erythrocyte membranes
Authors: Ruggiero F. M. , Gnoni G. V. , Quagliariello E. 
Published: November 2006

AbstractThe effect of hydrothyroidism on plasma and erythrocyte membrane lipid components has been investigated. This pathological state is accompanied by a) a cholesterol increase of about 60% in plasma, and at the same time a 22% reduction in erythroycte membranes; b) 44% and 30% phospholipid level decreases in both plasma and red cell membranes, respectively; and c) almost unaffected phospholipid and fatty acid compositions of both plasma and erythrocyte membranes. All changes were corrected by treatment of the hypothyroid rats with triiodothyronine for two days. These findings suggest that in hypothyroid rats a reduced transfer of cholesterol from plasma to erythrocyte membrane probably takes place. This could explain, at least in part, the increased hematic cholesterol level observed in hypothyroid animals. In red cell membranes, the simultaneous decrease in cholesterol and phospholipid levels does not alter the cholesterol/phospholipid molar ratio, thus avoiding their abnormal function.
Role of the lymphatic system in the transport of absorbed 7,12‐dimethylbenzanthracene in the rat
Authors: Laher J. M. , Barrowman J. A. 
Published: November 2006

AbstractTo determine the role of the intestinal lymphatic system in the absorption of a polycyclic aromatic hydrocarbon, 7,12‐dimethylbenzanthracene, a radiolabeled preparation of the compound was given by intraduodenal infusion to rats in doses of 10 μg, 10 mg and 20 mg in olive oil solution. The hydrocarbon appeared to be absorbed from the intestine in a fractional manner, ca. 20% of the administered radioactivity being recovered totally in bile and intestinal lymph in 24 hr at all three dose levels. Biliary radiolabel accounted for 75–82% of combined recovery of radioactivity in bile and lymph with all three doses. The recovery of significant amounts of radiolabel in bile before the appearance of isotope in lymph, together with the fact that the biliary radiolabel greatly exceeded at all times the lymphatic recovery of isotope, suggests that an alternative pathway, presumably the portal venous route, is of major importance in the transport of the absorbed hydrocarbon.
Nonenzymatic hydrolysis of phosphatidylcholine prepared as liposomes and mixed micelles
Authors: Ho Rodney J. Y. , Schmetz Mark , Deamer David W. 
Published: November 2006

AbstractNonenzymatic hydrolysis of phosphatidylcholine was investigated at several pH ranges in liposomes and mixed micelles. Phosphatidylcholine was stable to hydrolysis for 140 hr at pH 4, 7 and 10, but slowly hydrolyzed at pH 1 with a half‐time of 50 hr. We conclude that phosphatidylcholine is not significantly degraded by hydrolysis under conditions typical for liposome preparation methods.
Membrane fatty acid modification in tumor cells: A potential therapeutic adjunct
Authors: Burns C. Patrick , Spector Arthur A. 
Published: November 2006

AbstractThe fatty acid compositions of several tumors have been modified sufficiently to alter some of their properties and functions. These modifications were produced in culture by adding specific fatty acids to the growth medium or by feeding fat‐supplemented diets to tumor‐bearing mice. The phospholipid fatty acid composition of the plasma membrane was modified, but there were no changes in membrane phospholipid or cholesterol content or in phospholipid head group composition. Each of the most abundant membrane phosphoglyceride fractions exhibited some degree of fatty acid modification. Electron spin resonance measurements with nitroxystearate spin probes indicated that the fatty acid modifications were sufficient to alter the physical properties of the plasma membrane. The Km′ for methotrexate uptake was reduced when the L1210 leukemia cells were enriched in linoleic acid. Even when the kinetics of uptake at 37 C were not altered, such as for melphalan and phenylalanine uptake, the temperature transition of transport was modified, indicating that these transport systems also are responsive to the membrane fatty acid modifications. Enrichment with highly polyunsaturated fatty acid did not affect either the growth rate or radiosensitivity of the L1210 leukemia. However, the sensitivity of the L1210 cells to the cytotoxic effects of Adriamycin and hyperthermia was increased. These findings suggest the possibility that fatty acid modification of tumors may be a useful adjunct to certain currently available therapeutic modalities.
Biochemical characterization of acetyl‐CoA:1‐alkyl‐2‐lyso‐sn‐glycero‐3‐phosphocholine acetyltransferase in rat spleen microsomes
Authors: Seyama Kuniaki , Ishibashi Teruo 
Published: November 2006

AbstractAcetyl‐CoA:1‐alkyl‐2‐lyso‐sn‐glycero‐3‐phosphocholine (lyso‐PAF) ultrasonic disruption in the presence of 25% glycerol from rat spleen microsomes. About 26% of the enzymatic activity was recovered in the 225,000×g supernatant by this treatment, although the specific activity was slightly decreased compared with the original microsomes. The solubilized enzyme was remarkably susceptible to various kinds of metal ions. Sulfhydryl reagents such as p‐chloromercuribenzoate and N‐ethyl‐maleimide significantly inhibited the enzyme reaction, suggesting that the enzyme is an SH enzyme. Based on the sedimentation pattern in sucrose density centrifugation, the isoelectric point, the kinetic characteristics and the sensitivity to tryptic digestion of microsomes, it appears that acetyl‐CoA:lyso‐PAF acetyltransferase does not differ from the acetyltransferase responsible for the transfer of acetate from acetyl‐CoA to 1‐acyl‐2‐lyso‐sn‐glycero‐3‐phosphocholine.
Two new icosapentaenoic acids from the temperate red seaweedPtilota filicina J. Agardh
Authors: Lopez Albert , Gerwick William H. 
Published: November 2006

AbstractTwo new fatty acid metabolites, 5(Z),7(E),9(E),14(Z),17(Z)‐icosapentaenoic acid and 5(E),7(E),9(E),14(Z),17(Z)‐icosapentaenoic acid, have been isolated from the temperate red marine alga,Ptilota filicina (Ceramiales, Rhodophyta). The structures of these new compounds, isolated as their methyl ester derivatives, have been deduced from detailed1H nuclear magnetic resonance (NMR),13C NMR and 2D‐NMR analyses as well as comparisons to known compounds.
Measurement of lipid peroxidation in vivo: A comparison of different procedures
Authors: Pompella Alfonso , Maellaro Emilia , Casini Alessandro F. , Ferrali Marco , Ciccoli Lucia , Comporti Mario 
Published: November 2006

AbstractA study was undertaken to investigate whether some of the methods commonly used to detect lipid peroxidation of cellular membranes in vivo correlate with each other. The study was performed with the livers of bromobenzene‐intoxicated mice, in which lipid peroxidation develops when the depletion of glutathione (GSH) reaches a threshold value. The methods tested and compared were the following: i) measurement of the malondialdehyde (MDA) content of the liver; ii) detection of diene conjugation absorption in liver phospholipids; iii) measurement of the loss of polyunsaturated fatty acids in liver phospholipids; and iv) determination of carbonyl functions formed in acyl residues of membrane phospholipids as a result of the peroxidative breakdown of phospholipid fatty acids. Correlations among the values obtained with these methods showed high statistical significances, indicating that the procedures measure lipid peroxidation in vivo with comparable reliability. Analogously, the four methods appeared also to correlate when applied to in vitro microsomal lipid peroxidation.
Alteration of chain length selectivity of aRhizopus delemar lipase through site‐directed mutagenesis
Authors: Joerger Rolf D. , Haas Michael J. 
Published: November 2006

AbstractThe coding sequences of theRhizopus delemar lipase and prolipase were altered by oligonucleotide‐directed mutagenesis to introduce amino acid substitutions. The resulting mutant enzymes, synthesized by the bacterial hostEscherichia coli BL21 (DE3), were tested for their ability to hydrolyze the triglycerides triolein (TO), tricaprylin (TC) and tributyrin (TB). Mutagenesis and lipase gene expression were carried out using plasmid vectors derived from previously described recombinant plasmids [Joerger and Haas (1993)Lipids 28, 81–88] by introduction of the origin of replication of bacteriophage fl. Substitution of threonine 83 (thr83), a residue thought to be involved in oxyanion binding, by alanine essentially eliminated lipolytic activity toward all substrates examined (TB, TO and TC). Replacement of thr83 with serine caused from two‐ to sevenfold reductions in the activity toward these substrates. Introduction of tryptophan (trp) at position 89, where such a residue is found in closely related fungal lipases, reduced the specific activity toward the three triglyceride substrates. For the mutagenesis of residues in the predicted acyl chain binding groove, mutagenic primers were designed to cause the replacement of a specific codon within the prolipase gene with codons for all other amino acids. Phenylalanine 95 (phe95), phe112, valine 206 (val206) and val209, were targeted. A phenotypic screen was successfully employed to identify cells producing prolipase with altered preference for olive oil, TC or TB. In assays involving equimolar mixtures of the three triglycerides, a prolipase with a phe95→asparatate mutation showed an almost twofold increase in the relative activity toward TC. Substitution of trp for phe112 caused an almost threefold decrease in the relative preference for TC, but elevated relative TB hydrolysis. Replacement of val209 with trp resulted in an enzyme with a two‐ and fourfold enhanced perference for TC and TB, respectively.
Effects of soybean lipoxygenase‐1 on phosphatidylcholines containing furan fatty acids
Authors: Batna Andreas , Spiteller Gerhard 
Published: November 2006

AbstractNaturally occurring tetraalkylsubstituted furan fatty acids (F‐acids) were tested as potential substrates for soybean lipoxygenase‐1. For this purpose, F‐acid methyl ester and phosphatidylcholines containing F‐acids at thesn‐2 position of the glycerol residue wer incubated with the enzyme. Oxidation of F‐acids only occurs in the presence of linoleic acid as co‐substrate. Linoleic acid is converted by lipoxygenase to the corresponding hydroperoxide that oxidizes the F‐acid, probably in a radical reaction, to form an unstable dioxoene compound. This intermediate the forms, dependent on pH, unsaturated furanoid acids or isomers with cyclopentenolone structure that can be detected by gas chromatography/mass spectrometry (GC/MS). F‐acids located at thesn‐2 position of a synthetic phosphadidylcholine (PC), containing linoleic acid in thesn‐1 position, are co‐oxidized to a greater extent by incubation with soybean lipoxygenase‐1 than are F‐acids bound to PC with myristic acid in thesn‐1 position when subjected to the enzyme in the presence of a great excess of linoleic acid. The results suggest that F‐acids may play a strategic role in antioxidative processes in plant cells.
Cholesterol secretion from hepatocytes induced by triacylglycerol and apolipoprotein E
Authors: Quarfordt Steven H. , Landis Barry A. , Farouk Marwan O. , Oswald Brian S. 
Published: November 2006

AbstractThe mechanism for the increase in plasma cholesterol levels in cholesterol‐fed rats following chylomicron transport was investigated in intact animals, in isolated perfused liver, and in hepatocytes in monolayer cultures. Intravenous administration of egg phosphatidylcholine in amounts greater than those required to cause a plasma cholesterol response when given as chylomicrons was without effect. This makes it unlikely that increased plasma cholesterol levels resulted from the recruitment of tissue cholesterol by the plasma chylomicron phospholipids that persisted in the plasma after triacylglycerol clearance. The hepatic origin of the increased plasma cholesterol levels was directly confirmed by two hepatic perfusion experiments. When cholesterol‐fed rats received intravenous chylomicrons prior to isolated hepatic perfusion, more cholesterol was secreted by the liver than when the rats were injected intravenously with buffer. Perfusion of apolipoprotein E (apo E)‐rich triacylglycerol emulsions through the livers also enhanced cholesterol secretion. The increase in hepatocyte cholesterol secretion seen with cholesterol‐fed rats was also noted in monolayer cultures following incubation with apo E rich‐triacylglycerol emulsions. The apolipoprotein or the emulsion alone, or apo E‐rich phosphatidylcholine liposomes, had no effect. The data confirm previous indirect observations that the liver is the source of cholesterol that appears in plasma following transport of chylomicrons or following a lipid‐rich meal in cholesterol‐fed rats. The data also re‐emphasize the importance of providing apo E with triacylglycerol emulsions to initiate secretion of lower density lipoproteins by the liver.
A cross‐species comparison of neutral lipid composition of milk fat of prosimian primates
Authors: Myher J. J. , Kuksis A. , Tilden C. , Oftedal O. T. 
Published: November 2006

AbstractThe fatty acid composition of milk fat is known to be affected by dietary and genetic differences, while the milk triacylglycerol structure is believed to be attuned to the needs of the subsequent lipolysis during gastrointestinal passage. The availability of milk samples from eight species of prosimian primates, whose milk triacylglycerol structure had not been analyzed, offered an opportunity to further assess these ideas. The milk samples were collected by manual expression and the lipids extracted with chloroform/methanol (2∶1, vol/vol). The lipid classes were resolved by thin‐layer chromatography, and the neutral lipids subjected to detailed analyses by capillary gas‐liquid chromatography of fatty acids and molecular species of triacylglycerols using nonpolar and polarizable liquid phases. The milk samples were found to differ greatly in total fat content (4–73%) and in the composition of the neutral liqid classes and molecular species. The concentration of triacylglycerols ranged from 88–95%, free fatty acids from 0.5–10%, alkyldiacylglycerols from 0.5–5.0%, and diacylglycerols, monoacylglycerols and free and esterified cholesterol made up the remainder. The fatty acid chain length ranged from C8−C24, with palmitic (16–31%) and oleic (13–40%) acids being the major components in most of the species. In all instances, the molecular association of the fatty acids differed from random distribution by a higher proportion of the monoacid (trioleoyl) and diacid (dipalmitoyloleoyl) glycerols. The phylogenetic influences on neutral milk lipid composition, however, remained unclear, as some of the differences between closely related species were greater than those between more distantly related ones.
Sterol and fatty acid composition of neutral lipids ofParatenuisentis ambiguus and its host eel
Authors: Weber Nikolaus , Vosmann Klaus , Aitzetmüller Kurt , Filipponi Christin , Taraschewski Horst 
Published: November 2006

AbstractThe sterol composition of free sterol and steryl ester fractions of the fish parasiteParatenuisentis ambiguus was determined. In addition, the fatty acid composition of various neutral lipid classes, i.e., wax esters, steryl esters, triacylglycerols and free fatty acids, as well as the composition of the 1‐O‐alkyl moieties of total ether glycerolipids of the parasite, were investigated. The results of these studies were compared with those obtained on the intestinal tract tissue of its host, the eel (Anguilla anguilla). Cholesterol is the major sterol in bothP. ambiguus andA. anguilla. However, the sterols ofP. ambiguus contain high proportions (>20%) of other sterols, such as campesterol and various dehydrosterols. [e.g., 7‐dehydrocholesterol and cholesta‐5,22(E)‐dienol]. The presence of these minor sterols agrees with the known biotransformations of exogenous sterols in various helminths. Considerable differences are found in the fatty acid composition of neutral lipid fractions, as well as the total lipid extract from the endoparasite as compared to the host tissue. In particular, eicosapentaenoic acid (20∶5n−3), other polyunsaturated fatty acids, such as 20∶4n−6, 22∶5n−3 and 22∶6n−3, as well as long‐chain saturated fatty acids, such as 20∶0, are generally enriched in the neutral lipid fractions of the parasite as compared to those of infected eel intestine. The analysis of ether glycerolipids revealed that 1‐O‐hexadecyl (16∶0) and 1‐O‐hexadecenyl (16∶1) moieties were present in similar proportions in the ether lipids of bothP. ambiguus and eel intestine, whereas 1‐O‐octadecyl (18∶0) moieties are more prominent in the parasite and 1‐O‐octadecenyl (18∶1) moieties in the eel. The results of these studies show thatP. ambiguus has specific mechanisms for the regulation of the sterol and fatty acid composition of its neutral lipids.
Identification of a deoxyguanosine‐malondialdehyde adduct in rat and human urine
Authors: Agarwal Sanjiv , Wee Jae Joon , Hadley Mary , Draper Harold H. 
Published: November 2006

AbstractIn an ongoing study, rat and human urine have been examined for the presence of malondialdehyde (MDA) derivatives as indicators of the nature of lipid peroxidative damage caused by this compoundin vivo. MDA in urine was found to be present mainly in the form of two lysine adducts, one acetylated and the other unacetylated, reflectingin vivo reactions with tissue proteins. Two minor metabolites were identified as adducts with the phospholipid bases serine and ethanolamine and a third one as an adduct with the nucleic acid base guanine. The identification of an MDA adduct with deoxyguanosine (dG‐MDA) among the products of hydrolysis of rat liver DNA suggested the possible occurrence of this compound in urine. In the present study dG‐MDA was identified in rat and in human urine, and a high‐performance liquid chromatographic method utilizing fluorescence detection was developed for its estimation. The method is sensitive to 1 pmol of dG‐MDA and requires a minimum of 1 mL of rat urine or 5 mL of human urine. Its rate of excretion by five‐week‐old rats (28.54±2.28 nmol/kg/24 h) (mean±SEM) was higher than that for nine‐week‐old rats (6.29±1.02) and much higher than that for adult humans (0.40±0.05). The results indicate that, as reported for 8‐hydroxy‐deoxyguanosine, dG‐MDA excretion is related to metabolic rate. Excretion of dG‐MDA by the rat, like the excretion of total MDA, declines during growth on a body weight basis at a rate similar to the decrease in resting energy metabolism. In contrast to other MDA derivatives excreted in rat urine, vitamin E deficiency had no effect on the excretion of dG‐MDA. Together with evidence that the dG‐MDA content of rat liver DNA likewise is unaffected by vitamin E depletion or by administration of catalysts ofin vivo lipid peroxidation, these findings indicate that DNA is protected from lipid peroxidative damage, possibly through conservation of the vitamin E associated with the lipids of the nuclear membrane.