bluuebunny/crossref_metadata_2025 huggingface dataset:
Arachidonic acid and eicosapentaenoic acid stimulate type II pneumocyte surfactant secretion
Authors: Baybutt Richard Carleton , Smith John Edgar , Gillespie Mark N. , Newcomb Terry G. , Yeh Yu‐Yan
Published: November 2006

Arachidonic acid and its leukotriene metabolites have been shown to stimulate surfactant secretion by alveolar type II cells. The present study was undertaken to determine the effects of various unsaturated fatty acids, including eicosapentaenoic acid, on surfactant secretion. Surfactant secretion was expressed as the percent of [3H]choline‐derived phospholipids released into culture medium by type II pneumocytes of adult rats. Consistent with the earlier findings, arachidonic acid stimulated secretion in a concentration‐dependent fashion (3.5–21 μM), doubling baseline secretion at 21 μM. Eicosapentaenoic acid was found to be equally effective as arachidonic acid in stimulating secretion. A comparison with palmitic, oleic and linoleic acids revealed that highly unsaturated fatty acids stimulated secretion to the greatest extent. This was supported by a positive correlation between degree of unsaturation (i.e., 0, 1, 2, 4 and 5 double bonds) and stimulation of surfactant secretion. In the present study, exogenous leukotriene E4 (10−13–10−6) did not stimulate surfactant secretion. Neither nordihydroguaiaretic acid (0.1μM) nor indomethacin (0.1μM) affected arachidonic acid‐stimulated secretion. The stimulatory effects of arachidonic acid and eicosapentaenoic acid on surfactant secretion were related to the highly unsaturated nature of the fatty acids and were not mediated by increased levels of cyclic adenosine monophosphate or calcium.
The lipid composition of selected tissues from a Mediterranean monk seal,Monachus monachus
Authors: Henderson R. James , Kalogeropoulos Nick , Alexis Maria N.
Published: November 2006

The lipid composition of blubber, brain, muscle and heart from a Mediterranean monk sealMonachus monachus (an endangered species) were examined to allow comparisons with more common species of seals. Only neutral lipids (mainly triacylglycerols) were detectable in the blubber lipids, whereas polar lipids predominated in the heart and in the brain. Neutral and polar lipids comprised almost equal proportions in both liver and muscle. Choline glycerophospholipids (CGP) were the major polar lipids, followed by ethanolamine glycerophospholipids (EGP) in the liver, heart and muscle. Cerebrosides accounted for 28.8% of the brain lipids. All lipid classes of the liver contained high levels (31–47%) of polyunsaturated fatty acids (PUFA), with the exception of phosphatidylserine. The total proportion of n−6 PUFA exceeded that of n−3 PUFA in all lipid classes of the liver, due mainly to the high levels of 20∶4n−6. The highest level of 20∶4n−6 occurred in phosphatidylinositol, where it comprised 32.4% of the total fatty acids. The CGP and EGP of the brain contained lower levels of PUFA than those of the liver, muscle and heart. Alkenyl ethers accounted for 35.8% of the total long‐chain moieties in brain EGP. The fatty acid composition of blubber triacylglycerols differed from those of the lipid classes from other tissues in that it had a very low ratio of n−6 to n−3 PUFA (0.3) as a result of a lower content of 20∶4n−6.
Comparison of the metabolism of α‐linolenic acid and its Δ6 desaturation product, stearidonic acid, in cultured NIH‐3T3 cells
Authors: Cantrill Richard C. , Huang Yung‐Sheng , Ells Gregory W. , Horrobin David F.
Published: November 2006

The incorporation and metabolism of α‐linolenic acid (18∶3n−3) and its Δ6 desaturase product, stearidonic acid (18∶4n−3), were compared by NIH‐3T3 cells. In the presence of fetal calf serum, cells accumulated exogenously added 18∶3n−3 and 18∶4n−3 apparently at the expense of oleic acid (18∶1n−9). Both 18∶3n−3 and 18∶4n−3 were elongated and desaturated to eicosatetraenoic acid (20∶4n−3), eicosapentaenoic acid (20∶5n−3) and docosapentaenoic acid (22∶5n−3), but not to docosahexaenoic acid (22∶6n−3), and were incorporated into phospholipids and triacylglycerols. Over a 4−d period, the growth of NIH‐3T3 cells was slightly stimulated in the presence of 18∶3n−3 (20 μg/mL) but was strongly inhibited in the presence of 18∶4n−3 at the same concentration. This inhibition may be caused by enhanced lipid peroxidation as a result of the high levels of 18∶4n−3 present.
The effect of culture medium composition on ether lipid cytotoxic activity
Authors: Diomede Luisa , Piovani Bianca , Modest Edward J. , Salmona Mario
Published: November 2006

The effect of a serum‐free medium (TNB‐100), compared to RPMI 1640 containing 10% fetal bovine serum (FBS), on the lipid composition of HL60 and K562 leukemic cells was investigated. The 10% FBS RPMI medium contained approximately three times more phospholipids (PL), about three times more protein and eight times more cholesterol (CHOL) than did the TNB‐100 medium. Cells cultured in TNB‐100 medium, referred to as HL60‐TNB and K562‐TNB cells, were significantly lower in PL and CHOL than 10% FBS RPMI cells, with about a threefold higher PL‐to‐CHOL ratio; however, these cells were significantly higher in protein content. Cells grown in TNB‐100 were also significantly more fluid than 10% FBS RPMI cells and were more sensitive to the fluidizing action of the ether lipid 1‐O‐octadecyl‐2‐O‐methyl‐rac‐glycero‐3‐phosphocholine. The 50% inhibitory dose of the drug was about 50% lower in TNB‐grown cells than in 10% FBS RPMI cells.
Synthesis of methyl 11,14,17‐eicosatrienoate‐3,3,4,4,8,8,9,9‐d8
Authors: Rakoff Henry
Published: November 2006

For use in metabolic studies, methyl 11,14,17‐eicosatrienoate‐3,3,4,4,8,8,9,9‐d8 was prepared by Wittig coupling of 3,6‐nonadienyltriphenylphosphonium iodide with methyl 11‐oxoundecanoate‐3,3,4,4,8,8,9,9‐d8 in the presence of butyl lithium. Theall cis isomer was separated by high‐pressure liquid chromatography using a reverse‐phase column. An unexpected by‐product, methyl 10,13,16‐nonadecatrienoate‐2,2,3,3,7,7,8,8‐d8, was also isolated. The structures and the configurations of the compounds were confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry.
Rapid purification of rabbit reticulocyte lipoxygenase for electron paramagnetic spectroscopy characterization of the non‐heme iron
Authors: Carroll Richard T. , Muller Jessica , Grimm Jennifer , Dunham William R. , Sands Richard H. , Funk Max O.
Published: November 2006

An efficient three‐step purification technique has been developed for the reticulocyte 15‐lipoxygenase from rabbit. Ammonium sulfate fractionated reticulocyte lysate was purified by size exclusion chromatography and preparative scale isoelectric focusing. The entire procedure was complete in less than eight hours and was carried out in batches which typically yielded 10 mg of purified enzyme. The identity and purity of the enzyme were evaluated byN‐terminal sequencing, sodium dodecylsulfate polyacrylamide gel electrophoresis and specific activity determinations. The enzyme contained approximately one g‐atom iron per mole of protein. The iron was present in an electron paramagnetic spectroscopy (EPR) silent, presumably high spin iron(II), form in the isolated enzyme. Treatment with one equivalent of 13‐hydroperoxy‐9(Z),11(E)‐octadecadienoic acid resulted in the appearance of an EPR signal around g6.
A thermospray mass spectrometric assay for Fe‐induced 4‐hydroxynonenal in tissues
Authors: Blanchflower W. John , Walsh Dominic M. , Kennedy Seamus , Kennedy D. Glenn
Published: November 2006

A method is presented for the determination of 4‐hydroxy‐nonenal (HNE) in tissue homogenates followingin vitro lipid peroxidation induced by iron (Fe++). NHE is measured as the pentafluorobenzyl oxime derivative using liquid chromatography thermospray mass spectrometry.In vitro metabolism of HNEvia the glutathione/glutathione‐S‐transferase pathway was inhibited using iodoacetic and iodobenzoic acids. The assay has been used as an indicator of the peroxidizability of tissue samples from animals both adequate in and depleted of α‐tocopherol. The concentrations of HNE produced in tissues taken from animals depleted of α‐tocopherol were found to be up to 8 times higher than those taken from animals supplemented with α‐tocopherol.
The effects of clofibrate and bezafibrate on cholesterol metabolism in the liver of the male rat
Authors: Shand J. H. , West D. W.
Published: November 2006

Fibric acid derivatives are used to treat hyperlipidemia and have wide ranging effects on lipid metabolism. The action of these compounds on cholesterol esterification, catalyzed by acyl‐coenzyme A:cholesterol acyltransferase (ACAT), has been quite widely studied, but their effect on cholesteryl ester hydrolysis and the enzyme neutral cholesteryl ester hydrolase (nCEH) has been largely ignored. Male rats were therefore fed for 10 d on a standard chow diet supplemented with either clofibrate or bezafibrate, to study their effects on plasma lipid levels and hepatic cholesterol metabolism. Plasma triacyglycerols were not significantly altered by these diets, but bezafibrate significantly lowered plasma cholesterol levels (29.7%,P<0.01). When expressed per unit weight of DNA, both fibrates reduced the hepatic content of triacylglycerol, cholesterol and cholesteryl esters (40, 18.7, 16.5 and 66.7, 28.6, 34.2% for clofibrate and bezafibrate, respectively). ACAT activity was significantly reduced by both drugs, but clofibrate (65% inhibition) was more effective than bezafibrate (35% inhibition). The most dramatic effect of the diets was a marked increase in the activity of both the microsomal and the cytosolic nCEH. When expressed on a whole liver basis, the effect of bezafibrate on the cytosolic enzyme (13.6‐fold increase in activity) was much greater than that of clofibrate (4.8‐fold increase). Increases in the activity of a cytosolic protein that inhibits the activity of nCEH were also noted, but these changes were relatively small. The results suggest that the activation of nCEH, in combination with the inhibition in ACAT activity, contributes to a decrease in the cholesteryl ester content of the liver which may influence the secretion of very low density lipoprotein.
Absorption of isomeric, palmitic acid‐containing triacylglycerols resembling human milk fat in the adult rat
Authors: de Fouw Nanneke J. , Kivits Gerard A. A. , Quinlan Paul T. , van Nielen Wim G. L.
Published: November 2006

The effect of the positional distribution of palmitic acid (16∶0) in triacylglycerols (TAG) on 16∶0 apparent absorption in adult rats was investigated. The rats were fed two diets which contained 30 energy % as fat with identical total fatty acid compositions, both containing 30% 16∶0. The Betapol diet contained TAG with 73% of total 16∶0 in thesn‐2 position, the control diet contained TAG with 6% of total 16∶0 in thesn‐2 position. After six weeks on these diets, the rats were killed two or six hours after the last meal, and the small intestine was removed, cut into 10‐cm segments, and the fatty acid composition of the segment's contents was determined. At both time points the amount of 16∶0 in the intestinal segments starting at 40 cm from the stomach was much lower in the animals fed Betapol than in the animals fed the control diet. Overall absorption of 16∶0 and stearic acid was significantly greater in the Betapol group. Absorption of oleic and linoleic acid from the small intestine was similar in both groups, although the overall absorption was significantly greater in the animals fed Betapol. Total fat absorption was significantly higher in the Betapol‐fed rats than in the control‐fed rats. No effect on calcium and nitrogen absorption, on plasma total cholesterol and TAG levels, and on bodyweights (growth) was seen. The data demonstrate that the positional distribution of the fatty acids in the TAG molecule affects the site of absorption in the small intestine and particularly the net absorption of saturated fatty acids.
Effects of low casein and fish oil on hyperlipidemia and proteinuria in nephritic rats
Authors: Fujisawa Kiyohito , Yagasaki Kazumi , Funabiki Ryuhei
Published: November 2006

The effects of amino acid‐fortified low casein and fish oil (FO) diets on hyperlipidemia and proteinuria were studied in rats with nephrotoxic serum nephritis. After an antiserum injection, rats were maintained for 14 d on four different experimental diets: a 20% casein diet containing corn oil (CO) or FO, or an 8% casein diet supplemented with cystine plus threonine containing CO or FO. The 8% casein diets reduced urinary protein excretion in nephritic rats without inducing severe growth retardation or fatty liver compared with the basal 20% casein diets. Both the 8% casein diet and the FO diet decreased serum cholesterol, triglyceride and phospholipid levels in nephritic rats, and nonesterified fatty acid levels were decreased by FO feeding. In nephritic animals, hepatic cholesterol synthesis was decreased by the 8% casein diets compared with the 20% casein diets, and tended to be reduced by FO feeding between groups at the same casein levels. No effect of diet was observed on fatty acid synthesis among the nephritic rats. FO administration to the nephritic animals suppressed fecal steroid excretion. While lipoprotein lipase activity was unchanged among the nephritic rats, hepatic triglyceride lipase activity was reduced by either the 8% casein or FO diet. The results suggest that the hypolipidemic action of low casein diets may, at least in part, be due to reduced hepatic cholesterol synthesis and suppressed triglyceride secretion from the liver. They also suggest that the hypolipidemic action of FO may, at least in part, be due to reduced hepatic cholesterol synthesis and decreased fatty acid mobilization from peripheral adipose tissue.
Structural and functional role of lipids in yeast and mycelial forms ofCandida albicans
Authors: Goyal Sawraj , Khuller G. K.
Published: November 2006

The levels of total lipids, sterols and phospholipids were found to be significantly higher in the mycelial form (log phase) ofCandida albicans than in the yeast form. Increased phospholipid levels in the mycelial form were due to higher levels of phosphatidylcholine, phosphatidylserine and phosphatidylinositol. Analyses of fatty acid composition also revealed higher levels of myristic acid (40%) in the yeast form, resulting in higher levels of saturated lipids than in the mycelial form. The changes in the lipid composition were also manifested in altered thermotropic phase behavior as gel‐to‐liquid crystalline phase transitions were observed at 36 and 27°C for the lipids of the yeast and mycelial forms, respectively. These changes coincided with higher uptake rate, i.e., Km and Vmax values, for the transport of L‐proline and with a higher sensitivity of the mycelial form against antifungal drugs.
Kinetic study of quenching reactions of singlet oxygen and scavenging reactions of free radicals by α‐, β‐, λ‐ and σ‐tocopheramines in ethanol solution and micellar dispersion
Authors: Itoh Shingo , Nagaoka Shin‐ichi , Mukai Kazuo , Ikesu Satoru , Kaneko Yutaka
Published: November 2006

Quenching reactions of singlet oxygen and scavenging reactions of free radicals by α‐, β‐, λ‐ and σ‐tocopheramines (Toc‐amines) were investigated spectrophotometrically in ethanol and Triton X‐100 micellar dispersions. The rate constants of quenching of singlet oxygen (kQ) by α‐, β‐, λ‐ and σ‐Toc‐amines increased as the total electron donating capacity of the methyl groups at the aromatic ring increased. A plot of logkQ vs. peak oxidation potential (Ep) was found to be linear and the slope was negative. Similar results were obtained for scavenging of a phenoxyl radical (PhO.). The results suggest that charge transfer plays an important role in these reactions. ThekQ values were found to be 1.30–2.57 times as large askQ for α‐tocopherol (α‐Toc). Although α‐Toc has the highest antioxidant activity among natural tocopherols and related phenols, Toc‐amines also can serve as antioxidants.
The reaction of low levels of nitrogen dioxide with methyl linoleate in the presence and absence of oxygen
Authors: Gallon Aris A. , Pryor William A.
Published: November 2006

The reaction of methyl linoleate with low levels of nitrogen dioxide in a carrier gas, such as helium or air, at nitrogen dioxide concentrations ranging from 2 to 228 ppm was studied and the products formed were monitored. In both aerobic and anaerobic conditions, low concentrations of nitrogen dioxide reacted with methyl linoleate predominately to form allylic products. When a 1∶1 mixture of methyl palmitate/methyl linoleate was layered over an aqueous buffer and a nitrogen dioxide stream was passed from underneath, so that the stream passed through the aqueous layer before contacting the organic layer, allylic products again predominated. In the absence of air, the allylic products consisted of allylic nitro and nitrite derivatives of linoleate, whereas in the presence of air, allylic hydroperoxides were the principal products. The findings suggest that fatty acids with doubly allylic hydrogen atoms react preferentially by a hydrogen atom abstraction reaction rather than by the addition of nitrogen dioxide to a double bond.
A31P nuclear magnetic resonance investigation of acyl group transfer from phosphatidylcholine to yield lysophosphatidylcholine in human plasma
Authors: Nouri‐Sorkhabi M. Hossein , Sullivan David R. , Roberts David C. , Kuchel Philip W.
Published: November 2006

31P nuclear magnetic resonance (NMR) spectroscopy was used to measure the rate of acyl transfer from phosphatidylcholine (lecithin, PC) in whole plasma and in high density lipoprotein (HDL). Spectral deconvolution was used to resolve overlapping resonances in the31P NMR spectra of the phospholipids. Mean values of the acyl group transfer rates from PC in plasma and HDL were 36 μmol L−1h−1 and 19 μmol L−1h−1, respectively. The reciprocal nature of the decrease in the spectral peak intensities of PC, compared to the increase in the intensities of the lysolecithin (lysoPC) peaks, suggested a substrate/product relationship consistent with the action of lecithin:cholesterol acyltransferase (LCAT), the enzyme responsible for the esterification of free cholesterol in plasma. LCAT involvement was confirmed by measuring the cholesterol esterification rate based on the13C NMR spectra obtained on lipid extracts from plasma that had been incubated at 37°C. Within experimental error, the rate of lysoPC formation in plasma was shown to be equal to that of cholesteryl ester formation.
Garlic reduces plasma lipids by inhibiting hepatic cholesterol and triacylglycerol synthesis
Authors: Yeh Yu‐Yan , Yeh Shaw‐Mei
Published: November 2006

Prompted by the reported hypolipidemic activity of garlic, the present study was undertaken to elucidate the mechanism(s) underlying the cholesterol‐lowering effects of garlic. Rat hepatocytes in primary culture were used to determine the short‐term effects of garlic preparations on [1‐14C]acetate and [2‐3H]glycerol incorporation into cholesterol, fatty acids and glycerol lipids. When compared with the control group, cells treated with a high concentration of garlic extracts [i.e., petroleum ether‐ (PEF), methanol‐ (MEF) and water‐extractable (WEF) fractions from fresh garlic] showed decreased rates of [1‐14C]acetate incorporation into cholesterol (by 37–64%) and into fatty acids (by 28–64%). Kyolic containingS‐allyl cysteine and organosulfur compounds inhibited cholesterogenesis in a concentration dependent manner with a maximum inhibition of 87% at 0.4 mM. At this concentration, Kyolic decreased [1‐14C]acetate incorporation into fatty acids by 67%.S‐allyl cysteine at 2.0 and 4.0 mM inhibited cholesterogenesis by 20–25%. PEF, MEF and WEF depressed the rates of [2‐3H]glycerol incorporation into triacylglycerol, diacylglycerol and phospholipids in the presence of acetate, but not in the presence of oleate. The results suggest that the hypocholesterolemic effect of garlic stems, in part, from decreased hepatic cholesterogenesis, whereas the triacylglycerol‐lowering effect appears to be due to inhibition of fatty acid synthesis. Primary hepatocyte cultures as used in the present study have been proven useful as tools for screening the anticholesterogenic properties of garlic principles.
Effect of fish oil on cancer cachexia and host liver metabolism in rats with prostate tumors
Authors: Dagnelie Pieter C. , Bell Jimmy D. , Williams Steve C. R. , Bates Timothy E. , Abel Paul D. , Foster Christopher S.
Published: November 2006

The aim of this study was to investigate whether tumor‐induced cachexia and aberrations in host liver metabolism, induced by the MAT‐LyLu variant of the Dunning prostate tumor, could be prevented by ω3 fatty acids from fish oil. On day 0, adult Copenhagen‐Fisher rats fed normal chowad libitum were inoculated with 106 MAT‐LyLu cells (n=14) or saline (n=9). On day 7, when tumors were palpable, four tumor‐bearing (TB) and four nontumorbearing (NTB) rats were put on isocaloric diets with 50% of total energy as fish oil. The introduction of fish oil‐enriched diets caused a reduction in energy intake to less than half of the energy intake by animals fed normal diets during days 7–14 (difference by dietary group: NTB,P<0.001; TB,P<0.001). During days 14–21, energy intake in fish oil‐fed animals returned to approximately 75% of energy intake by animals fed normal diets (difference by dietary group: NTB,P<0.003; TB,P=0.001). Carcass weight of animals on day 21, when the study was terminated, was significantly related to initial weight (P=0.05) and mean food intake during the study (P=0.01). When data were adjusted for these variables using analysis of covariance, with NTB animals on normal diets being the reference group, significant loss of carcass weight was observed in TB animals on normal diets only (mean ±SEM 58±10 g loss,P<0.001), but not in TB animals on fish oil diets (8±18 g loss,P=0.67). This positive effect of fish oil diets on carcass weight in TB animals was statistically significant (50±19 g,P<0.02), implicating that the fish oil enriched diet inhibited tumor‐induced weight loss by more than 85%. No effect of fish oil diets on tumor growth was detected. In all TB animals, regardless of diet, hepatic [Pi]/adenosine triphosphate] ratios measured by31P magnetic resonance spectroscopy (MRS)in vivo andin vitro were elevated, and absolute concentrations of phosphocholine, glycerophosphocho‐line, glycerophosphoethanolamine and glucose‐6‐phosphate as determined by31P MRSin vitro were reduced. Ultrastructural studies of liver tissue revealed increased numbers of mitochondria and increased amounts of endoplasmic reticulum in the host liver of TB animals, without differences between dietary group. In conclusion, fish oil supplementation partially inhibited MAT‐LyLu tumor‐induced cachexia, but did not prevent the majority of31P MRS‐detectable alterations in host liver metabolism.
Synthesis ofE,E‐diene hydroperoxides via photoisomerization of protected hydroperoxides
Authors: Dussault P. H. , Lee I. Q. , Eary C. T.
Published: November 2006

A general approach toE,E‐diene hydroperoxides is described based upon photoisomerization of readily availableZ,E‐diene monoperoxyketals. Protection of aZ,E‐diene hydroperoxide as the 2‐methoxypropyl peroxyketal is followed by iodine‐mediated photoisomerization to produce a mixture enriched in theE,E isomer. After chromatographic purification, deprotection of the peroxyketal with mild acid furnishes theE,E‐diene hydroperoxide.
Effect of peroxyl radicals on lecithin/cholesterol acyltransferase activity in human plasma
Authors: Chen Chen , Loo George
Published: November 2006

The objective of this study was to determine whether subjecting human plasma to oxidant stress reduces the activity of lecithin/cholesterol acyltransferase (LCAT, EC 2.3.1.43). Plasma was incubated for 4h with 2.25–45 mM of 2,2′‐azobis(2‐amidinopropane)HCl (AAPH), a source of peroxyl radicals. A time‐ and concentration‐dependent reduction of LCAT activity occurred, relative to control samples incubated in the absence of AAPH. Reduction of LCAT activity was disproportionate to elevation of thiobarbituric acid‐reactive substances (TBARS) in the plasma. Added ascorbate was able to significantly prevent reduction of LCAT activity, but this effect was unrelated to blockage of TBARS formation by the antioxidant. The results suggest that LCAT activity can be down‐modulated by oxidant stress, but not necessarily by lipid peroxidation.
Kinetic analysis of cardiolipin synthase: A membrane enzyme with two glycerophospholipid substrates
Authors: Schlame Michael , Zhao Ming , Rua Diego , Haldar Dipak , Greenberg Miriam L.
Published: November 2006

Mitochondrial cardiolipin synthase catalyzes the transfer of a phosphatidyl moiety from phosphatidyl‐CMP PtdCMP) to phosphatidylglycerol (PtdGro) in the presence of specific divalent cations. The synthase was solubilized fromSaccharomyces cerevisiae mitochondria and purified about 300‐fold. The partially purified enzyme was part of a medium‐size, mixed micelle which had to bind to a foreign substrate/detergent micelle before catalysis could occur. The kinetics of cardiolipin synthase were studied by changing the molar fraction of substrate in the micelles. The enzyme obeyed Michaelis‐Menten kinetics in relation to PtdCMP with aKm of 0.03 mol%. PtdGro caused sigmoidal kinetics with a low apparent affinity. it is speculated that it was involved in docking the enzyme to the substrate/detergent micelle. Cardiolipin synthase did not catalyze isotope exchange between [14C]CMP and PtdCMP, virtually excluding a ping‐pong catalytic mechanism. Mg2+stimulated the activity by increasing the turnover number rather than the substrate affinity, a mechanism which was also found for the Co2+‐activation of rat liver cardiolipin synthase. It is concluded that a direct association of the metal ion and the enzyme forms the active cardiolipin synthase which has a very high affinity for PtdCMP and a lower affinity for PtdGro.
Synergistic induction of phospholipid metabolism by granulocyte‐macrophage colony stimulating factor and steel factor in human growth factor‐dependent cell line, M07e
Authors: Mantel C. , Luo Z. , Broxmeyer H. E.
Published: November 2006

Steel factor (SLF), the ligand for the c‐kit protooncogene tyrosine kinase receptor, synergizes with several hematopoietic growth factors to produce greatly enhanced proliferation of normal human hematopoietic progenitor cells as well as that of the human growth factor‐dependent myeloid cell line, M07e. The mechanisms of this phenomenon remain unknown. In an attempt to understand the cellular processes relevant to this phenomenon, we examined the effects of SLF and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) on induced lipid metabolism in M07e cells. We find that both GM‐CSF and SLF induced increased phosphatidylcholine (PC) turnover rates (biosynthesis and degradation) as measured by increased [3H]‐choline labelling, with SLF being more potent stimulation. The labelling of aqueous intermediates of PC metabolism was also increased by cytokine stimulation, most notably phosphocholine. Simultaneous stimulation with GM‐CSF plus SLF resulted in a true synergistic induction of PC, lysoPC, and phosphocholine labelling. GM‐CSF and SLF each induced asymmetric labelling of various phospholipid classes as measured by incorporation of different [3H]‐fatty acids. [3H]‐myristic acid labelling of phosphatidylserine was most prominently induced (approximately 12‐fold). Cytosolic choline kinase activity was also upregulated more than twofold over control by SLF, which might contribute to the increased phosphocholine labelling. These effects may have relevance to the intracellular mechanisms of the synergistic proliferative stimulation of SLF plus GM‐CSF on M07e cells.
Plasma fatty acids and lipids in two separate, but genetically comparable, icelandic populations
Authors: Skúladóttir Gudrún V. , Gudmundsdóttir Sigrún , Ólafsson Gunnlaugur B. , Sigurdsson Stefán B. , Sigfússon Nikulás , Axelsson Jóhann
Published: November 2006

Levels of serum lipids and lipoproteins, and the fatty acid composition of plasma phospholipids, were measured in two genetically comparable, but widely separated, populations. The 1975 mortality rates for ischemic heart disease were significantly higher in one of these populations, the Manitoban residents of pure Icelandic descent, than in the other, a rural population from Northeastern Iceland. Two study populations, Icelanders and Icelandic‐Canadians, were drawn from these larger populations. The study populations were matched for age and sex and divided into three age groups, 20–39, 40–59, and 60–69 years. In comparison to the Icelandic‐Canadians, the Icelanders exhibited significantly higher levels of total cholesterol, low‐density lipoprotein cholesterol, and high‐density lipoprotein cholesterol, but lower triglyceride levels. Their plasma phospholipids contained significantly lower levels of saturated fatty acids (SFA), monounsaturated fatty acids, and n−6 polyunsaturated fatty acids (PUFA); but their n−3 PUFA levels were three times as high. It was additionally found that fatty acid composition of plasma phospholipids differed among Icelanders of different ages. SFA levels were significantly lower, and n−6 PUFA levels significantly higher, in the 20–39 year group than in the 60–69 year group, possibly due to different dietary fat consumption patterns between generations. No corresponding age‐related difference in the fatty acid composition of plasma phospholipids was found in the Icelandic‐Canadian study population. As the Icelandic and Icelandic‐Canadian groups are assumed to be genetically similar, the biochemical differences between them are evidently due to environmental, probably dietary, differences. The findings indicate that n−3 PUFA may be cardioprotective in the context of an otherwise atherogenic diet.
Determination of lysine modification product ε‐N‐pyrrolylnorleucine in hydrolyzed proteins and trout muscle microsomes by micellar electrokinetic capillary chromatography
Authors: Zamora Rosario , Navarro José L. , Hidalgo Francisco J.
Published: November 2006

ε‐N‐Pyrrolylnorleucine (Pnl) is a product of the reaction between the lipid peroxidation product 4,5(E)‐epoxy‐2(E)‐heptenal (EH) and the ε‐amino group of lysine. Because Pnl might also be produced in proteins, a specific method to determine this compound in protein hydrolysates has been developed. Homoarginine, added as the internal standard, and Pnl are derivatized with diethyl ethoxymethylenemalonate and analyzed by micellar electrokinetic capillary chromatography. The method also analyzes lysine and arginine, and these analyses were useful in determining losses of these amino acids after treatment with EH. The lowest concentration of Pnl detected with acceptable reproductibility is 5 nmol/mL, and the coefficient of variation was determined from four standard curves assayed on separate days. Detector response was linear for samples containing 1.6 to 74 nmol/mL of Pnl. The assay was applied in investigations of Pnl production in bovine serum albumin (BSA) and trout muscle microsomes treated with EH. When BSA was incubated overnight with 30 mM EH, 76% of lysine residues were modified, and a part of these residues were detected as Pnl (12%). Pnl formation was also detected when trout muscle microsomes were incubated for three hours with 1 or 10 mM EH. These results show that Pnl is producedin vitro in proteins treated with the lipid peroxidation product EH, and suggest that Pnl might also be constituent ofin vivo damaged proteins by their reaction with oxidized lipids.
Plasma and lipoprotein lipid peroxidation in humans on sunflower and rapessed oil diets
Authors: Turpeinen Anu M. , Alfthan Georg , Valsta Liisa , Hietanen Eino , Salonen Jukka T. , Schunk Hanna , Nyyssönen Kristiina , Mutanen Marja
Published: November 2006

The effects of natural mixed diets on lipid peroxidation were investigated in humans. In the first study, 59 subjects were fed a rapeseed oil‐based diet rich in monounsaturated fatty acids (MUFA) and a sunflower oil‐based diet rich in polyunsaturated fatty acids (PUFA) in a cross‐over manner for three and a half weeks. The lipid peroxidation products in plasma were determined by measuring conjugated dienes and malondialdehyde (MDA). In a second study, plasma thiobarbituric acid reactive substances (TBARS), lipid hydroperoxides, and the susceptibility of very low density lipoprotein + low‐density lipoprotein (LDL) toin vitro oxidation were measured from subjects fed similar MUFA and PUFA diets for six week diets. No significant differences in plasma MDA or conjugated diene concentrations were found after the rapeseed oil diet or the sunflower oil diet in Study 1. In the second study, a small but significant decrease (P<0.05) in both lipid hydroperoxides and TBARS was observed in the LDL fraction after the sunflower oil diet. Thein vitro oxidation gave opposite results, showing increased oxidation after the sunflower oil diet. Despite a high intake of α‐tocopherol during the oil peroids, no increase in plasma α‐tocopherol was noticed in either study. The results suggest that moderate changes in the fatty acid composition in the Western‐type diet may be adequate to affect lipoprotein susceptibility to oxidationin vitro, but there is considerable disparity with some indices ofin vivo lipid peroxidation.
Annexin I in female rabbit reproductive organs: Varying levels in relation to maturity and pregnancy
Authors: Tsao Francis H. C. , Chen Xiaoru , Chen Xiaoming , Ts'ao Chung‐hsin
Published: November 2006

The level of annexin I, a 36 kDa calcium‐dependent phospholipid‐binding protein (36 kDa PLBP) in the reproductive organs of young, mature, and pregnant rabbits was determined immunologically with antibodies raised against purified rabbit lung annexin I. In the cytosolic fractions of the ovary, fallopian tube, uterus, and placenta, annexin I was the only major immunoreactive protein. The reproductive organs appeared to have higher annexin I levels than most nonreproductive organ tissues, except the lung and the spleen which were also rich in annexin I. A small amount of annexin I and a nearly equal amount of its hydrolytic product, a 33 kDa polypeptide, were detected in the amniotic fluid between 21 and 27 days gestation. Structural similarity of annexin I in the reproductive organs and in the lung was suggested by their identical isoelectric point values. Annexin I in the ovary of adult rabbits was 70% higher than that in the respective organ of immature rabbits. The uterus of pregnant rabbits had about 84% higher annexin I contents than that of the nonpregnant rabbits., The placenta had more annexin I per mg cytosolic protein than either the ovary or the uterus during pregnancy. The high concentration of annexin I in the reproductive organs may reflect specific functions of these organs in the reproductive years and during the reproductive cycle.
Changes in ether‐linked phospholipids in rat kidney by dietary α‐linolenic acidin vivo
Authors: Park Jin H. , Park Eek J. , Kim Kye S. , Yeo Young K.
Published: November 2006

We investigated the effects of perilla oil containing a high level of α‐linolenic acid onin vivo phospholipid metabolism, particularly three subclasses of choline glycerophospholipids (CGP) and ethanolamine glycerophospholipids (EGP), in rat kidney. After three weeks of feeding, a significantly lower proportion (by 35%) of the alkylacyl subclass of CGP was found in the perilla oil, as compared to corn oil‐fed animals. The alkylacyl species of EGP was also higher in the perilla oil than in the corn oil‐fed animals. These alterations were accompanied by a remarkably lower proportion of arachidonic acid and a higher level of eicosapentaenoic acid (EPA) in all six subclasses of CGP and EGP in the perilla oil‐fed animals. The levels of linoleic acid were even higher in the diacyl subclasses of CGP and EGP in the perilla oil group, suggesting that desaturase and elongase enzymes prefer n−3 to n−6 fatty acids as substrates for diacyl species. These data are useful in defining the effects of α‐linolenic acid on the biosynthesis of renal phospholipids and on the replacement of n−6 with n−3 fatty acids in the six CGP and EGP subclasses.
Effects of dietary oil related to the toxic oil syndrome on the lipids of guinea pig liver microsomes
Authors: de la Casa E. , Pérez‐González N. , Sánchez‐Bernal C. , Llanillo M.
Published: November 2006

The potential effects of oil specimens related to cases of toxic oil syndrome (TOS) on the liver microsomal lipid composition from guinea pigs were investigated. For four weeks, animals were fed diets supplemented with either “case oil” (oil related to cases of TOS) or “control oil” (oil unrelated to cases of TOS), either previously heated or not. Results were compared with those from guinea pigs fed the same diet with no oil. The administration of case oil produced changes in liver microsomal lipid composition. Statistically significant differences were also found between heated case and heated control oils. The cholesterol/phospholipid molar ratios and the major phospholipid class distribution were unaffected under these diet conditions. However, increases in the relative contents of linoleic and arachidonic acids and, simultaneously, a reduction in palmitic and palmitoleic acid levels were observed by diet effects. Heated oil administration decreased the saturated/unsaturated ratios in all cases. Our data suggest that changes observed in the fatty acid composition are attributable to the free fatty acid contents of administered oils. The toxic constituents of case oil seem to be able to alter the liver microsomal lipid composition.
High‐performance liquid chromatography with light‐scattering detection and desorption chemical‐ionization tandem mass spectrometry of milk fat triacylglycerols
Authors: Spanos George A. , Schwartz Steven J. , van Breemen Richard B. , Huang Chien‐Hua
Published: November 2006

The utility of reverse‐phase high‐performance liquid chromatography (HPLC), desorption chemical‐ionization mass spectrometry (DCI‐MS) and tandem mass spectrometry (MS/MS) for the characterization of triacylglycerols in complex mixtures has been further explored. Triacylglycerols of anhydrous bovine milk fat were separated by using two reversephase C18 HPLC columns, and eluents were monitored with an evaporative light‐scattering detector. Fifty‐eight fractions were resolved and analyzed by positive ion isobutane DCI‐MS. The formation of protonated molecules and of major fragments corresponding to the random loss of any one of the constituent fatty acids readily identified acyl carbon numbers and the number of double bonds within each fatty acid. MS/MS was only required when the original mass spectra indicated the presence of more than one triacylglycerol or of impurities in a fraction. Protonated molecules produced by DCI were fragmented using high energy collisional activation, and the resulting ions were detected by MS/MS. Odd‐chain triacylglycerols were also readily distinguished using this methodology. The positive ion DCI and MS/MS techniques described here demonstrate the usefulness of this approach for the characterization of triacylglycerols in complex mixtures.
Nonmembrane associated dolichol in rat liver
Authors: Löw P. , Peterson E. , Edlund C. , Brunk U. , Appelkvist E. L.
Published: November 2006

The distribution of dolichol in rat liver was studied. Upon high‐speed centrifugation, 9% of the total tissue dolichol was recovered in the supernatant. Dolichol was enclosed in vesicles and in lipidic particles which were isolated by gel filtration and density gradient centrifugation. The particles had a diameter of 20 nm and contained dolichol, ubiquinone, cholesterol, phospholipid and some protein. Similar particles were recovered upon incubation of isolated hepatocytes with liposomes containing dolichol. From the lysosomal lumen, lipid particles containing dolichol, ubiquinone, cholesterol and phospholipid, but no protein, were isolated. The diameter of the particles was 20–40 nm with a molecular weight of 130 kDa. Puromycin treatment inhibited protein synthesis, but did not affect dolichol transfer from the endoplasmic reticulum to lysosomes, suggesting that the transfer is not mediated by newly synthesized apoprotein. The results indicate that a sizeable portion of the total cellular dolichol is present in cytoplasm and in lysosomal lumen. Furthermore, dolichol probably participates in the translocation process.
Compartmental study of rat renal phospholipid metabolism
Authors: Sterin‐Speziale Norma , Kahane Veronica L. , Setton Clara Patricia , Fernandez Maria del Carmen , Speziale Emir H.
Published: November 2006

Phospholipid content and metabolism were studied in rat renal papillary, medullary and cortical slices. The highest concentration of phospholipids was found in cortex and the lowest in papilla samples (ratio cortex/medulla, 1.3; cortex/papilla, 3.7). The profile of the various phospholipids was different depending on the zone. The most important difference was the relative concentrations of sphingomyelin (CerPCho) and phosphatidylinositol (PtdIns) with ratios for PtdIns/CerPCho of 5.0, 3.3 and 2.5 in papilla, medulla, and cortex, respectively. In the three zones, PtdIns showed the highest specific activity for [2‐14C]glycerol and [1‐14C]arachidonic acid incorporation. By contrast, a higher amount of [1‐14C]palmitic acid was incorporated into phosphatidylcholine than into any other phospholipid. The various radioactive precursors were only poorly incorporated into phosphatidylethanolamine. No radioactivity was associated with phosphatidylserine. The papilla possesses the most active phospholipid metabolism of all the pathways studied.
Effect of human mammary MX‐1 tumor on plasma free fatty acids in fasted and fasted‐refed nude mice
Authors: Lin Chu , Blank Edward W. , Ceriani Roberto L. , Baker Nome
Published: November 2006

We hypothesized that tumor‐bearing (TB) nude mice, because they are reported to have no detectable, circulating tumor necrosis factor (TNF)/cachectin, would regulate their plasma free fatty acid (FFA) levels normally when fasted and refed. We compared levels of individual plasma FFA in response to fasting (24 hr) and to refeeding (for 20 hr after fasting) a fat‐free, 65% sucrose diet in control, nude mice and in mice bearing 1.3±0.4 g MX‐1 tumors. Total plasma FFA levels were typically high in 24‐hr fasted mice [mean concentrations in μM±SE (n); controls 515±63 (6); TB, 625±63 (6)]. FFA levels were reduced by 65% in each group in response to refeeding. Each major plasma FFA species fell in response to refeeding, except arachidonate, which did not change significantly (fastedvs. fasted‐refed concentrations) in either controls or TB mice. In refed mice, the molar FFA ratio of oleate to linoleate rose; however, that of oleate to arachidonate fell markedly. TB nude mice had normal appetites. We conclude that all species of FFA were mobilized from adipose tissue in a normal manner in TB nude mice; therefore, regulation of adipose triacylglycerol fatty acid mobilization (as plasma FFA) by dietary sugar is probably not affected by MX‐1 tumor growth in these mice. Our findings are consistent with the hypothesis that nude mice may be unable to secrete TNF/cachectin in response to tumor growth, but they do not establish whether or not endogenous, circulating TNF/cachectin increases FFA mobilization in any TB animal.
Glutathione and antioxidants protect microsomes against lipid peroxidation and enzyme inactivation
Authors: Hu Miao‐Lin , Tappel Al L.
Published: November 2006

The study investigated the relationship between lipid peroxidation and enzyme inactivation in rat hepatic microsomes and whether prior inactivation of aldehyde dehydrogenase (ALDH) exacerbated inactivation of other enzymes. In microsomes incubated with 2.5 μM iron as ferric sulfate and 50 μM ascorbate, ALDH, glucose‐6‐phosphate (G6Pase) and cytochrome P450 (Cyt‐P450) levels decreased rapidly and concurrently with increased levels of thiobarbituric acid‐reactive substances. Microsomal glutathioneS‐transferase and nicotinamide adenine dinucleotide phosphate‐cytochromec reductase were little affected during 1 hr of incubation. Addition of reduced glutathione partially protected, andN,N′‐diphenyl‐p‐phenylenediamine and butylated hydroxytoluene completely protected microsomes against inactivation of ALDH, G6Pase and Cyt‐P450, as well as lipid peroxidation induced by iron and ascorbate. ALDH was more susceptible than G6Pase to inactivation by iron and ascorbate, and was thus an excellent marker for oxidative stress. Inhibition of ALDH by cyanamide injection of rats exacerbated the inactivation of G6Pase in microsomes incubated with 0.1 mM, but not 25 μM 4‐hydroxynonenal (4‐HN). 4‐HN did not stimulate lipid peroxidation. Thus, 4‐HN may play a minor role in microsomal enzyme inactivation. In contrast, lipid, peroxyl radicals play an important role in microsomal enzyme inactivation, as evidenced by the prevention of both lipid peroxidation and enzyme inactivation by chain‐breaking antioxidants.
Formation of formaldehyde and malonaldehyde by photooxidation of squalene
Authors: Yeo H. C. H. , Shibamoto T.
Published: November 2006

Formaldehyde and malonaldehyde were identified upon exposure of squalene to ultraviolet (UV) irradiation at 300 nm. Formaldehyde was derivatized by reaction with cysteamine to form thiazolidine; malonaldehyde was derivatized by reaction withN‐methylhdyrazine to produceN‐methylpyrazole. The derivatives were subsequently analyzed with a gas chromatography equipped with a fused silica capillary column and a nitrogen/phosphorus detector. The levels of formaldehyde and malonaldehyde produced increased with irradiation time. The amount of formaldehyde produced reached a maximum of 3.40 nmol/mg squalene after 7 hr irradiation; the maximum amount of malonaldehyde generated, 0.92 nmol/mg, was found after 5 hr of irradiation. Prior to this study, formaldehyde had not been reported as a photoproduct of squalene. Acetaldehyde and acetone were also detected in the irradiated squalen,, which may be formedvia a 6‐methyl‐5‐hepten‐2‐one intermediate. 6‐Methyl‐5‐hepten‐2‐one can also undergo breakdown to form malonaldehyde.
Acute toxicity oftrans‐5‐hydroxy‐2‐nonenal in fisher 344 rats
Authors: Nishikawa Akiyoshi , Sodum Rama , Chung Fung‐Lung
Published: November 2006

The potential toxicity oftrans‐4‐hydroxy‐2‐nonenal (HNE), a product formedin vivo during lipid peroxidation, which is also present in foods, was investigated in Fisher 344 rats. Five groups of five male rats each were given by gavage 1000, 300, 100, 30 or 10 mg/kg body weight HNE dissolved in 0.5 mL corn oil. The sixth group, the control, received corn oil alone. Two rats died 6 and 8 hr after being treated with 1000 mg/kg HNE. These two rats showed extensive acute tubular necrosis of the kidney, but had very little liver damage. Diffuse liver cell necrosis was observed in a dose dependent manner in all the rats killed 14 days after treatment, whereas renal change was mild. Interestingly, body weight of the lowest dosage group was significantly higher than that of the control group at termination of the experiment. The results of this study show that HNE has almost the same toxicity as other enals, such astrans‐2‐heptenal, and that kidney and liver are the main organs affected by toxicity of HNE. Although animals may have efficient defense systems, such as glutathione, to detoxify low to moderate dosages of HNE, at high doses of HNE this defense system is overwhelmed, resulting in serious renal and hepatic damage.