bluuebunny/crossref_metadata_2025_split huggingface dataset:
CDPcholine:1,2‐diacylglycerol cholinephosphotransferase from rat liver microsomes. I. Solubilization and characterization of the partially purified enzyme and the possible existence of an endogenous inhibitor
Authors: Ishidate Kozo , Matsuo Ritsuko , Nakazawa Yasuo 
Published: November 2006

AbstractThe solubilization and partial purification of cholinephosphotransferase (CDPcholine:1,2‐diacylglycerol cholinephosphotransferase, EC 2.7.8.2) from rat liver microsomes were examined in the presence of ionic (sodium deoxycholate), nonionic (Triton X‐100,n‐octylglycoside), or zwitter ionic (CHAPS) detergents. Among the four detergents tested, only sodium deoxycholate was found to be an efficient solubilizer of cholinephosphotransferase activity from microsomal membranes, whereas the other three detergents caused irreversible inactivation of the enzyme at the solubilization step. Addition of phospholipids at the solubilization step, or after solubilization of the membrane proteins, could not preserve or reconstitute activity to any extent. The sodium deoxycholate‐solubilized activity was partially purified by gel permeation chromatography (Superose 12HR). The partially purified preparation appeared to consist of a large aggregate containing phospholipids; further dissociation of the protein‐phospholipid complex caused complete inactivation of the enzyme. The partially purified cholinephosphotransferase showed a specific activity of 100–130 nmol/min/mg protein, which is the highest activity reported to date from any tissue source; this amounts to a 4‐fold enrichment of cholinephosphotransferase activity from the original KCl‐washed rat liver microsomes. Ethanolaminephosphotransferase (CDPethanolamine:1,2‐diacylglycerol ethanolaminephosphotransferase, EC 2.7.8.1) activity was copurified and 6‐fold enriched with a total recovery of 60%. During the purification of cholinephosphotransferase activity, a putative endogenous inhibitor of cholinephosphotransferase was also solubilized and was isolated from the microsomal membranes. This heat‐labile, nondialyzable inhibitor was shown to act specifically on cholinephosphotransferase and not on ethanolaminephosphotransferase. Further characterization of the inhibitory activity revealed that it may act at the binding step of the cholinephosphotransferase to its lipid substrate, diacylglycerol.
Hypertension in rats does not potentiate hypercholesterolemia and aortic cholesterol deposition induced by a hypercholesterolemic diet
Authors: Mori Hiromi , Ishiguro Kyohko , Okuyama Harumi 
Published: November 2006

AbstractThe effect of a hypercholesterolemic diet (HCD) on hyperlipemia and atherogenesis was investigated using normotensive Wistar/Kyoto rats (WKY), spontaneously hypertensive rats (SHR) and stroke‐prone SHR (SHRSP), with systolic blood pressures increasing in that order. Feeding an HCD diet containing cholesterol, cholate and suet induced hypercholesterolemia in all the strains examined as compared with a normal diet. The plasma cholesterol levels were significantly higher in WKY than in SHR and SHRSP fed the HCD diet. The HCD diet also induced hepatic fat deposition, particularly deposition of cholesteryl esters, a slight increase in aortic cholesterol deposition, and elevation of both monoenoic/saturated fatty acid ratios and linoleate/arachidonate ratios in tissue lipids. The changes induced in the three strains by the HCD diet were not positively correlated with blood pressures. The HCD diet affected hepatic acyl‐CoA:cholesterol acyltransferase and plasma lecithin:cholesterol acyltransferase activities differently in WKY and SHR which, in addition to the induction of Δ9 desaturase, may partly account for the difference in the diet‐induced changes in the fatty acid compositions of plasma cholesteryl esters. The results indicate that hypertensionper se does not stimulate the development of hypercholesterolemia and arterial cholesterol deposition induced by an HCD diet, suggesting that other factors are involved.
The relationship between fatty acid peroxidation and α‐tocopherol consumption in isolated normal and transformed hepatocytes
Authors: Cogrel Pascale , Morel Isabelle , Lescoat Gerard , Chevanne Martine , Brissot Pierre , Cillard Pierre , Cillard Josiane 
Published: November 2006

AbstractThe response of normal and transformed rat hepatocytes to oxidative stress was investigated. Isolated normal rat hepatocytes and differentiated hepatoma cells (the Fao cell line was derived from the Reuber H 35 rat hepatoma) in suspension were incubated with the ADP/Fe3+ chelate for 30 min at 37°C. Membrane lipid oxidation was assessed by measuring (i) free malondialdehyde (MDA) production by a high‐performance liquid chromatography (HPLC) procedure, (ii) membrane fatty acid disappearance as judged by capillary gas chromatography, and (iii) α‐tocopherol oxidation as determined by HPLC and electrochemical detection. The addition of iron led to increased MDA production in normal as well as in transformed cells, and to simultaneous consumption of polyunsaturated fatty acids (PUFA) and α‐tocopherol. In addition, in Fao cells more α‐tocopherol was consumed during lipid peroxidation while less PUFA was oxidized. Lipid peroxidation was lower in tumoral hepatocytes than in normal cells. This could be due to a difference in membrane lipid composition because of a lower PUFA content and a higher α‐tocopherol level in Fao cells. During oxidation, Fao cells produced 1.5 to 2 times less MDA than normal cells, while in the tumoral cells the amount of oxidized PUFA having 3 or more double bonds was 7 to 8 times lower. Therefore, measuring MDA alone as an index of lipid peroxidation did not allow for proper comparison of the membrane lipid oxidizability of transformed cellsvs. the membrane lipid oxidizability of normal cells.
Determination of 4‐hydroxynonenal by high‐performance liquid chromatography with electrochemical detection
Authors: Goldring Christopher , Casini Alessandro F. , Maellaro Emilia , Del Bello Barbara , Comporti Mario 
Published: November 2006

Abstract4‐Hydroxy‐trans‐2‐nonenal (HNE) is a highly reactive product of lipid peroxidation originating from the breakdown of phospholipid‐bound polyunsaturated fatty acids of cellular membranes. Despite its biological relevance, this aldehyde is only occasionally determined due to the complexity of previously described procedures. Here we present a simple and very sensitive method for the detection of HNE in biological samples. The method is based on the measurement of the 2,4‐dinitrophenylhydrazone (DNPH) of the aldehyde by electrochemical detection after separation by reverse‐phase high‐performance liquid chromatography (HPLC). The greater sensitivity of this procedure as compared to the ultraviolet detection method commonly employed to measure DNPH derivatives of aldehydes after HPLC will allow the detection of HNE below the pmol level. The detection of HNE is highly reproducible even in normal tissues and cells. Increased amounts of HNE were detected in the livers of animals intoxicated with prooxidant agents such as carbon tetrachloride, bromotrichloromethane or bromobenzene. An exponential increase in HNE (and in malondialdehyde) was measured in peroxidizing liver microsomes (in the NADPH/Fe‐dependent system). The method is also suitable for the study of very small samples, since HNE could be detected in approximately 1 million cultured cells (polyoma virus‐transformed baby hamster kidney fibroblasts); the level rose after exposure of the cells to a Fe3+/ADP prooxidant system.
Microplate methods for determination of serum cholesterol, high density lipoprotein cholesterol, triglyceride and apolipoproteins
Authors: Shireman Rachel B. , Durieux Janine 
Published: November 2006

AbstractMicrotiter plate methods were developed for the enzymatic determination of serum total cholesterol (TC), high density lipoprotein cholesterol (HDL‐C) and triglyceride (TG), and for the turbidometric determination of apolipoproteins. The micromethods resulted in accurate, precise values that were in good agreement with the conventional spectrophotometric assays. The coefficient of variation for TC determinations was 4.5% or less and bias was 5% or less. The lipid micromethod assays are sensitive to 10 mg/dL or less, and the apolipoprotein assay to 1 mg/dL. Less than 100 μL of serum suffices for TC, TG and apoprotein assays; HDL‐C requires an additional 100 μL of serum. Advantages of the micromethods include reductions in assay time and in the amount of reagents required.
A lack of correlation among fatty acids associated with different lipid classes in human milk
Authors: Clark Richard M. , Hundrieser Kenneth E. 
Published: November 2006

AbstractThe fatty acids associated with triacylglycerol, cholesteryl ester, phosphatidylethanolamine, phosphatidylcholine and sphingomyelin in human milk were compared. Ten milk samples were selected for lipid class analysis based on their total lipid polyunsaturated/saturated fatty acid ratio (P/S ratio). The P/S ratio of the selected milk samples ranged from 0.3 to 0.8. Linoleic acid was the predominant fatty acid in milk to affect the P/S ratio. The percentage of linoleic acid in milk triacylglycerol was correlated (r=0.84,P<0.05) with the total milk lipid P/S ratio. Linoleic acid esterified to cholesterol was not correlated with total milk lipid P/S ratio but was correlated (r=−0.66,P<0.05) with the quantity of lipid in the milk. Linoleic acid in the phospholipid classes did not correlate with shift in P/S ratio of the total milk lipid or linoleic acid content of other lipid classes.
Docosahexaenoic acid in developing brain and retina of piglets fed high or low α‐linolenate formula with and without fish oil
Authors: Arbuckle L. Dianne , Innis Sheila M. 
Published: November 2006

AbstractDocosahexaenoic acid (22∶6n−3) can be synthesized in the liver and/or brain from α‐linolenic acid (18∶3n−3) and is required in large amounts in structural membranes of developing brain and retina. The adequacy and efficacy of formulas containing 18∶3n−3 and/or fish oil in providing 22∶6n−3 for deposition was investigated in piglets fed formula from birth to 15 days. The test formulas contained high (HL) or low (LL) 18∶3n−3 (3.9 or 0.7% of the total formula fatty acids, respectively), or low 18∶3n−3 plus fish oil (LL+FO) to provide C20 and C22 n−3 polyunsaturated fatty acids (0.8% of total fatty acids). Fatty acid analyses of synaptic plasma membrane and retina ethanolamine phospholipids (EPL), which are especially enriched in 22∶6n−3, were compared to those of 15‐day‐old piglets fed sow milk (SM). Feeding LL resulted in lower 22∶6n−3 in synaptic plasma membrane. Fatty acid levels in HL and LL+FO piglets were equivalent to SM, with the exception of lower 22∶5n−3 in the synaptic plasma membrane of LL+FO and in the retina of HL and LL+FO‐fed piglets. Levels of 22∶4n−6 were also lower in the retina of the LL+FO group. The results suggest formula 18∶3n−3 is at least 24% as effective as C20 and C22 n−3 fatty acids as a source of membrane 22∶6n−3. This study shows dietary 18∶3n−3, as the only n−3 fatty acid, can support deposition of comparable percentage of 22∶6n−3 to natural milk. Fish oil also supported tissue levels of 22∶6n−3 similar to natural milk; however, lower 22∶4n−6 may indicate possible inhibitory effects on n−6 metabolism.
Does a threshold for the effect of dietary omega‐3 fatty acids on the fatty acid composition of nuclear envelope phospholipids exist?
Authors: Venkatraman J. T. , Toohey T. , Clandinin M. T. 
Published: November 2006

AbstractExistence of a dietary maximal level or threshold for incorporation of ω3 fatty acids into membrane phospholipids is of interest as it may further define understanding of the dietary requirement for ω3 fatty acids. To test whether feeding increasing levels of dietary ω3 fatty acids continues to increase membrane ω3 fatty acid content, weanling rats were fed a nutritionally adequate semipurified diet which provided increasing amounts of C20 and C22 ω3 fatty acids, such as 20∶5ω3 and 22∶6ω3. Dietary 20∶5ω3 and 22∶6ω3 were provided by substituting a purified shark oil concentrate of high 22∶6ω3 content for safflower oil high in 18∶2ω6. After four weeks of feeding, nuclear envelopes from four animals in each diet group were prepared, lipid was extracted and phospholipids separated. Arachidonic acid content in membrane phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol and phosphatidylserine was significantly reduced by feeding increased dietary levels of ω3 fatty acids. Decline of 20∶4ω6 level in phospholipid tended to stabilize when the dietary content of total ω3 fatty acids reached 4–5% of total fatty acids. Above this level, dietary ω3 fatty acids did not result in a further decrease in membrane content of 20∶4nω6. Increase in membrane phospholipid content of 20∶5ω3 occurred as the dietary intake of ω3 fatty acids increased from 1.1% to 5% of total fatty acids. A dietary ω3 fatty acid level of 2.2–3% was sufficient to result in maximum incorporation of 22∶6ω3 into membrane phosphatidylcholine and phosphatidylethanolamine, but not into phosphatidylinositol or phosphatidylserine.
Esterification of fatty acids by bovine intramuscular and subcutaneous adipose tissues
Authors: Lin Kuen‐Chiun , Cross H. Russell , Smith Stephen B. 
Published: November 2006

AbstractExogenous fatty acid esterification in intramuscular and subcutaneous adipose tissues from 72‐hr fasted orad libitum fed Angus cattle was investigated. Intramuscular (interfascicular) and subcutaneous adipose tissue snips were obtained from the longissimus dorsi muscle and were incubated with radioisotopically labeled fatty acids (palmitate, stearate, oleate, linoleate or linolenate) at three different concentrations (0.3 mM, 0.6 mM and 2.0 mM) to assess rates of fatty acid incorporation into glycerolipids. Rates of fatty acid esterificationin vitro increased with fatty acid concentration in both intramuscular and subcutaneous adipose tissues. For all of the fatty acids investigated, triglycerides were the predominant products (60–85%). Subcutaneous adipose tissue had larger adipocytes and more actively (P<0.05) esterified fatty acids, with the exception of palmitate, than intramuscular adipose tissue. The rate of palmitate esterification was not different between tissues, although intramuscular adipose tissue esterified a greater proportion (P<0.10) of palmitate as triglyceride (85%) than did subcutaneous adipose tissue (75%). Relative rates of incorporation of fatty acids into lipids in intramuscular and subcutaneous adipose tissues were: palmitate > linolenate > linoleate > stearate. In general, 72‐hr fasting did not significantly reduce the rates of fatty acid incorporation in bovine adipose tissues. Results of this study revealed that: i) rates of exogenous fatty acid incorporation into adipose tissue lipids were dependent on the medium fatty acid concentration and adipose tissue depot; and ii) the relative esterification rates of the various fatty acidsin vitro did not necessarily reflect the proportion of these fatty acids in bovine adipose tissues.
Separation and spectral data of the six isomeric ozonides from methyl oleate
Authors: Wu Mingdan , Church Daniel F. , Mahier Thomas J. , Barker Steven A. , Pryor William A. 
Published: November 2006

AbstractThe structures of the products obtained on ozonation of methyl oleate have been re‐examined. The assignments for the six isomeric ozonides of methyl oleate have been made by1H and13C nuclear magnetic resonance (NMR), which were consistent with the retention times observed in high‐performance liquid chromatography; the assignments were confirmed by mass and infrared spectroscopy. Two triplets for the ozonide ring protons of thecis andtrans isomers in the normal (MOO1) and the two cross ozonides (MOO1 and MOO3) can be resolved by 400 MHz NMR. For MOO1 and MOO3, where the two ring carbons are equivalent, two peaks for the ring carbons of each cross ozonides are resolved in the13C NMR spectra, one for thecis and one for thetrans isomer. For MOO2, four peaks for the ring carbons are resolved in the13C NMR spectra, two for thecis and two for thetrans isomer.
Lipids of the earthwormLumbricus terrestris
Authors: Albro Phillip W. , Schroeder Joanna L. , Corbett Jean T. 
Published: November 2006

AbstractThe lipid composition of the earthwormLumbricus terrestris has been reexamined under conditions intended to avoid enzymatic and chemical alterations during storage, extraction, and fractionation procedures. The simple lipids included aliphatic hydrocarbons, steryl esters, glycerides, and at least nine different sterols, all though to be derived from the diet. Free fatty acids, previously considered to be major components of worm lipids, comprised only 0.3% of the total lipid weight. Phospholipids included (in order of relative abundance) phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, and phosphatidylinositol, as well as sphingomyelin. Glycolipids included cerebrosides and sulfatides containing both glucose and galactose, and gangliosides containing glucosamine and sialic acid. The fatty acid compositions of these lipid classes appeared to be a mixture of what are considered typical plant, bacterial, and animal acids. Several fatty acids found in the worms, includingcis‐vaccenic and eicosapentaenoic acids, were essentially absent from the dietary components, and it is concluded that these acids were synthesized in the worms. The earthworm derives much of its lipid adventitiously, but exerts at least some control over its tissue lipid composition.
Changes in fatty acid composition of phospholipids from liver microsomes and nuclei in rats fed a choline‐free diet
Authors: Kapoor Randhir , Ghoshal Amiya K. , Farber Emmanuel 
Published: November 2006

AbstractMale F‐344 rats were fed a choline‐free (CF) diet, and changes in phospholipid content, phospholipid fatty acids and phospholipase A2 activity in liver nuclei and microsomes were examined during the first 72 hr. Both nuclei and microsomes showed a decrease in phosphatidylcholine (PC) content. Microsomes showed an increase in PC arachidonate while nuclei showed a decrease. Also, microsomes showed increased activity of phospholipase A2 (PLA2) while nuclei did not. These observations are consistent with the hypothesis that the absence of diene conjugates in liver microsomes in the rats on the CF diet may reflect the increased rate of removal of peroxidized fatty acids by phospholipase A2.
Levels of thiobarbituric acid reactive substances and the cytocidal potential of gammalinolenic and docosahexaenoic acids on ZR‐75‐1 and CV‐1 cells
Authors: Bégin M. E. , Ells G. 
Published: November 2006

AbstractTo clarify the mechanism by which gammalinolenic acid (GLA) is more tumoricidal than docosahexaenoic acid (DHA), we have compared the incorporation of the respective exogenously added ethyl esters GLAe and DHAe into the phospholipids of tumorigenic ZR‐75‐1 and nontumorigenic CV‐1 cells relative to the ability of the cells to survive and to accumulate thiobarbituric acid reactive substances (TBARS). GLA and DHA were incorporated in the phospholipids to the same extent, but GLA disappeared more rapidly than DHA in both cell lines. GLAe induced about twice as much intracellular TBARS as DHAe in both cell lines, but killed ZR‐75‐1 cells four times more effectively than DHAe. DHAe induced 11–15 fmoles malondialdehyde‐equivalents (MDA‐eq)/cell in both ZR‐75‐1 and CV‐1 cells, whereas GLAe induced 5–6 times more TBARS in ZR‐75‐1 cells (26–30 fmoles MDA‐eq/cell) than in CV‐1 cells (5–6 fmoles MDA‐eq/cell). The results show that there is no difference in GLA and DHA incorporation into phospholipids, but that their metabolism differs in the two cell types. The data also suggest that the cytocidal potential is related to TBARS levels in a nonlinear fashion. The relationship between excess prostaglandin production and excessive cell death due to GLA is discussed.
Phospholipid composition of cultured human endothelial cells
Authors: Murphy Eric J. , Joseph Laurie , Stephens Ralph , Horrocks Lloyd A. 
Published: November 2006

AbstractDetailed analyses of the phospholipid compositions of cultured human endothelial cells are reported here. No significant differences were found between the phospholipid compositions of cells from human artery, saphenous and umbilical vein. However, due to the small sample sizes, relatively large standard deviations for some of the phospholipid classes were observed. A representative composition of endothelial cells is: phosphatidylcholine 36.6%, choline plasmalogen 3.7%, phosphatidylethanolamine 10.2%, ethanolamine plasmalogen 7.6%, sphingomyelin 10.8%, phosphatidylserine 7.1%, lysophosphatidylcholine 7.5%, phosphatidylinositol 3.1%, lysophosphatidylethanolamine 3.6%, phosphatidylinositol 4,5‐bisphosphate 1.8%, phosphatidic acid 1.9%, phosphatidylinositol 4‐phosphate 1.5%, and cardiolipin 1.9%. The cells possess high choline plasmalogen and lysophosphatidylethanolamine contents. The other phospholipids are within the normal biological ranges expected. Phospholipids were separated by high‐performance liquid chromatography and quantified by lipid phosphorus assay.
Unusual tetraene sterols in some phytoplankton
Authors: Patterson G. W. , Gladu P. K. , Wikfors G. H. , Lusby W. R. 
Published: November 2006

AbstractSterols were analyzed from four phytoplankton strains which are under investigation as possible sources of food for oysters in culture. One strain ofPyramimonas contained only 24‐methylenecholesterol as a major sterol component.Pyramimonas grossii, Chlorella autotrophica andDunaliella tertiolecta each contained a complex mixture of C28 and C29 sterols with Δ7, Δ5,7 and Δ5,7,9(11) nuclear double bond systems. Sterols were found both with and without the C‐22 side chain double bond. Ergosterol and 7‐dehydroporiferasterol were the principal sterols in each of the latter three species, which also contained the rare tetraene sterols, 24‐methylcholesta‐5,7,9(11),22‐tetraen‐3β‐ol and 24‐ethylcholesta‐5,7,9(11),22‐tetraen‐3β‐ol.
Comparison of the effect of the amount and degree of unsaturation of dietary fat on plasma low density lipoproteins in vervet monkeys
Authors: Kruger M. , Smuts C. M. , Benadé A. J. S. , Fincham J. E. , Lombard C. J. , Albertse E. A. , van der Merwe K. J. 
Published: November 2006

AbstractThe effects of the degree of unsaturation and of the amount of dietary fat on low density lipoprotein (LDL) concentration and composition were determined in vervet monkeys. Diets with fat contents of 41, 31 and 18% energy, each with a low and a high polyunsaturated to saturated fatty acid ratio (P/S; 0.27–0.38 and 1.13–1.47) were fed to six female vervet monkeys for two months. Another six females were given a low fat, high P/S diet for the same period of time, to serve as a reference. The cholesterol contents of the diets were low (21–33 mg per day) and relatively constant. LDL cholesterol concentrations decreased significantly (P≤0.01) when the dietary fat content decreased from 31 to 18% of energy. The dietary P/S ratio only affected LDL cholesterol concentrations during moderate (31% of energy) fat intake, where LDL cholesterol increased (P≤0.01) with a decrease in dietary P/S. Substantial individual variations were observed in LDL cholesterol concentration responses to dietary fat changes. The changes in LDL cholesterol concentrations were the result of changes in the concentration of LDL particles, as the molecular composition did not differ significantly between dietary periods. The high density lipoprotein choelsterol and the plasma triacylglycerol concentrations were not influenced by the dietary fat changes. During the high P/S diets, the percentage of 18∶2 (linoleic acid) increased (P≤0.01) and that of 18∶1 (oleic acid) decreased (P≤0.01) in LDL esterified cholesterol, as compared to the low P/S diets. In adipose tissue triacylglycerol the percentage of 18∶2 was three times higher (P≤0.01) during the high P/S diets than during the low P/S diets. A decrease in the amount of dietary fat (from 31 to 18% of energy) was associated with an increase in the percentage of 18∶1 in LDL esterified cholesterol.