bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of some potassium selective crown ethers on the permeability and structure of a phospholipid membrane
Authors: Szögy M. , Cerhati T. , Tölgyesi F.
Published: November 2006

The effect of some new crown ethers on the cation efflux and phase transition parameters of dipalmitoyl phosphatidylcholine liposomes was studied. The effects were correlated with the lipophilicity of the crown ethers. The results indicate that the presence of two crown ring structures in one crown ether molecule is a prerequisite for the increase of ion permeability of liposomes. The effective crown ethers decrease the temperature, enthalpy and cooperativity of the gel‐to‐liquid crystalline phase transition. The crown ethers increase membrane permeability for potassium and, to a lesser extent, for rubidium and sodium. The ratio of permeability increase for potassium/rubidium significantly correlates with the lipophilicity of the crown ethers.
Continuous monitoring of lipid peroxidation by measuring conjugated diene formation in an aqueous liposome suspension
Authors: Vossen Renée C. R. M. , van Dam‐Mieras Maria C. E. , Hornstra Gerard , Zwaal Robert F. A.
Published: November 2006

A method is described for the direct and continuous monitoring of lipid peroxidation in an aqueous suspension of sonicated liposomes. By means of ultraviolet difference spectroscopy using tandem cuvettes, the formation of conjugated dienes during liposome peroxidation can be followed. Using this technique, the effect of the fatty acid composition of liposomes on lipid peroxidation can be studied. The results show that both the extent and the time scale of lipid peroxidation are influenced by the fatty acid composition of the phospholipid liposomes. This was confirmed also by other methods, such as measurement of the formation of lipid hydroperoxides and measurement of the decrease in polyunsaturated fatty acids. The advantage of the method described is the direct and continuous monitoring of phospholipid peroxidation in an aqueous environment, without subsampling and extraction of peroxidation products into organic solvents. Using this experimental approach based on difference spectra the contributions from changes in liposome, CuSO4 and H2O2 concentrations are canceled, thus improving sensitivity. The method can be employed for measuring the susceptibility to peroxidation of membrane phospholipids from fatty acid modified endothelial cells.
Effects of non‐β‐oxidizable sulfur‐substituted fatty acid analogues on synthesis and secretion of triacylglycerol and cholesterol in cultured rat hapatocytes
Authors: Skorve Jon , Rustan Arild C. , Berge Rolf K.
Published: November 2006

The mechanisms behind the hypolipidemic effect of two sulfur‐substituted fatty acid analogues, 3‐thiadicarboxylic acid and tetradecylthioacetic acid, have been investigated in cultured hepatocytes. There was a dose‐dependent reduction in incorporation of [3H]water into triacylglycerol and diacylglycerol when tetradecylthioacetic acid was added to rat hepatocytes cultured in the presence of 200 μM oleic acid. Tetradecylthioacetic acid also increased the oxidation of [14C]palmitic acid compared to oleic acid, inhibited the incorporation of radiolabeled precursors into diacylglycerol to a greater extent than into triacylglycerol, and reduced the secretion of triacylglycerol more than its synthesis. A stimulation, rather than a reduction, in glycerolipid synthesis and secretion by tetradecylthioacetic acid was observed when oleic acid was omitted from the culture medium. When 3‐thiadicarboxylic acid was added to cultured hepatocytes, the effects on glycerolipid synthesis were generally similar to those observed with tetradecylthioacetic acid, but 3‐thiadicarboxylic acid did not increase the oxidation of [14C]palmitic acid. The two fatty acid analogues also had different effects on the synthesis and secretion of cholesterol and cholesteryl esters—3‐thiadicarboxylic acid reduced the incorporation of [3H]water into synthesized and secreted cholesterol and cholesteryl esters, whereas tetradecylthioacetic acid only reduced the secretion of cholesteryl esters without affecting its synthesis. It is concluded that tetradecylthioacetic acid increases the oxidation of fatty acids and reduces the synthesis and secretion of glycerolipids. 3‐Thiadicarboxylic acid reduces the synthesis and secretion of both glycerolipids and cholesterol to approximately the same extent without a concomitant increase in the oxidation of fatty acids.
The rare caribbean spongeLeucosolenia canariensis: Phospholipid fatty acids and sterols
Authors: Carballeira Néstor M. , Shalabi Fathi
Published: November 2006

The phospholipid fatty acid composition of the Calcarean spongeLeucosolenia canariensis was studied, and no Δ5,9 fatty acids were detected. These results are in contrast to the phospholipids from sponges belonging to the class Demospongiae where Δ5,9 fatty acids are predominant. Odd branched‐chain fatty acids between 17 and 19 carbons accounted for 26% of the total fatty acids ofL. canariensis, while straight‐chain fatty acids between 16 and 22 carbons accounted for 61% of the total fatty acid composition. The sterol composition ofL. canariensis is also reported, and only Δ5,7,22 sterols were observed.
Differential and interactive effects of calcium channel blockers and cholesterol content of the diet on jejunal uptake of lipids in rabbits
Authors: Hyson D. A. , Thomson A. B. R. , Kappagoda C. T.
Published: November 2006

The present study was undertaken to determine the effects of two classes of calcium channel blockers (CCB), nisoldipine (N) and verapamil (V), on the jejunal uptake of lipids in rabbits. The uptake of cholesterol and long‐chain fatty acids into rabbit jejunum was examined after 6 and 36 min of exposure to N or Vin vitro (“acute” studies), and after 3‐wk feeding of N or V (“chronic” studies). Animals were fed either a low (0.08%) cholesterol diet (LCD) or a high (2.8%) cholesterol diet (HCD), with or without N or V added. Acutein vitro exposure of the jejunum to N or V did not affect the uptake of cholesterol or palmitic acid in rabbits fed LCD or HCD. The effect of N or V feeding depended upon the cholesterol content of the diet; adding N or V to LCD increased cholesterol uptake while adding N or V to HCD enhanced or lowered cholesterol uptake, respectively. Both N and V increased the uptake of stearic acid in LCD. N in HCD had no effect on fatty acid uptake, whereas V lowered the uptake of stearic and linoleic acids and increased the uptake of oleic acid. These changes in lipid uptake were not due to variation in the animals' food intake, body weight gain, or intestinal mucosal surface area. The chronic administration of N or V results in an intestinal adaptive process that alters the jejunal uptake of lipids, the direction of which is influenced by the class of CCB, and by the cholesterol content of the diet. The serum lipid‐lowering effect of administering N to rabbits fed HCD demonstrated previously is unlikely to be the result of a decrease in intestinal lipid uptake.
Δ22‐β‐Muricholic acid in monoassociated rats and conventional ratsacid in monoassociated rats and conventional rats
Authors: Kayahara Takayuki , Tamura Toshihide , Amuro Yoshiki , Higashino Kazuya , Igimi Hirotsune , Uchida Kiyoshisa
Published: November 2006

Bile acids were analyzed in the bile, small and large intestines, and feces of germ‐free rats after a single inoculation with one of six intestinal bacteria that had been originally isolated from human feces.Bacteroides vulgatus andBifidobacterium longum preferentially deconjugated tauro‐β‐muricholic acid and taurocholic acid, respectively.Clostridium ramosum, Peptostreptococcus productus andLactobacillus gasseri deconjugated both bile acids, butEscherichia coli did not deconjugate either one. Rats inoculated with bacteria that deconjugated tauro‐β‐muricholic acid produced Δ22‐β‐Muricholic acid in the feces. In contrast, Δ22‐cholic acid could not be detected in rats inoculated with bacteria that deconjugated taurocholic acid.
Autoxidation of polyunsaturated triacylglycerols. IV. Volatile decomposition products from triacylglycerols containing linoleate and linolenate
Authors: Frankel E. N. , Selke E. , Neff W. E. , Miyashita K.
Published: November 2006

Trilinoleoylglycerol (LLL), trilinolenoylglycerol (LnLnLn) and four synthetic triacylglycerols were autoxidized and the volatile products were investigated to determine the effect of fatty acid glyceride position on the mechanism of hydroperoxide decomposition. Capillary gas chromatography provided a sensitive method to follow the volatile oxidation products of mixtures of LLL and LnLnLn and of synthetic triacylglycerols containing linoleate and linolenate in different known positions. The relative amount of linoleate oxidation was determined by analyzing for hexanal, 2‐heptenal and 2,4‐decadienal, and the relative amount of linolenate oxidation by analyzing for 2,4‐heptadienal and 2,4,7‐decatrienal. The volatiles from pure monohydroperoxides of LLL and LnLnLn were compared with those of the corresponding triacylglycerols by capillary gas chromatography. Significant differences in the distribution of volatile products were observed depending on the triacylglycerols precursor. A 1∶1 mixture of LLL and LnLnLn autoxidized at 40°C showed an equal contribution of linolenate and linoleate volatiles at a peroxide value of 34. The synthetic triacylglycerols LLnL and LLLn (L, linoleic; Ln, linolenic acid) formed initially about the same total volatiles, whereas LnLnL formed more volatiles than LnLLn. The ratio Ln to L volatile products was the same for the diL triacylglycerols, and higher for LnLnL than for LnLLn. This new information should permit us to better understand the influence of triacylglycerol structure on the relative oxidative stability of unsaturated triacylglycerols.
Separation of underivatized gangliosides by ion exchange high performance liquid chromatography
Authors: Whalen Marge M. , Wild Gaynor C. , Spall W. Dale , Sebring Robert J.
Published: November 2006

A procedure is described which separates neutral glycolipids from gangliosides, and which separates the gangliosides into classes, based on their number of sialic acid residues. In addition to separation into mono‐, di‐ and trisialoganglioside classes, there is purification of individual disialoganglioside species. The procedure uses a commercially available—NH2 high performance liquid chromatography (HPLC) column, which normally is used as an adsorption column. In this method the column is modified by protonation, to pH 5.4, so that it exhibits ion exchange as well as adsorption properties. Sensitive, nondestructive detection of eluent peaks is accomplished by monitoring continuously at 210 nm, a wavelength near which underivatized glycosphingolipids have absorbance maxima and which also will clearly detect most possible contaminants. An entire run, including re‐equilibration of the column, takes two hours.
Sterol pathway in yeast. Identification and properties of mutant strains defective in mevalonate diphosphate decarboxylase and farnesyl diphosphate synthetase
Authors: Chambon Christophe , Ladeveze Veronique , Servouse Madeleine , Blanchard Laurence , Javelof Catherine , Vladescu Barbu , Karst Francis
Published: November 2006

Yeast mutant strains auxotrophic for ergosterol and blocked in mevalonate diphosphate decarboxylase (erg19) and farnesyl diphosphate (FPP) synthetase (erg20) were isolated. The main feature of the mutants blocked in FPP synthetase is their ability to excrete prenyl alcohols, such as geraniol and farnesol. The isolation of the functionalERG20 gene allowed us to show that farnesyl diphosphate synthetase could be a rate limiting enzyme in ergosterol biosynthesis in yeast.
Effects ofbis homoallylic and homoallylic hydroxyl substitution on the olefinic13C resonance shifts in fatty acid methyl esters
Authors: Pfeffer Philip E. , Sonnet Philip E. , Schwartz Daniel P. , Osman Stanley F. , Weisleder David
Published: November 2006

Substitution of a hydroxyl group at thebis homoallylic position (OH group located three carbons away from the olefinic carbon) in C18 unsaturated fatty acid esters (FAE) induces a 0.73±0.05 ppm upfield and a 0.73±0.06 ppm downfield shift on the δ and ε olefinic13C resonances relative to the unsubstituted FAE, respectively. If the hydroxyl group is located on the carboxyl side of the double bond of thebis homoallylic hydroxy fatty acid esters (BHAHFA), the olefinic resonances are uniformly shifted apart by [|1.46+|Δδdbu‖] where Δδdbu represents the absolute value of the double bond resonance separation in the unsubstituted FAE and 1.46 ppm is the sum of the absolute values of the δ and ε shift parameters. With hydroxyl substitution on the terminal methyl side of the double bond, the olefinic shift separation is equal to [|1.46−|Δδdbu‖]. In homoallylic (OH group located two carbons away from the olefinic carbon) substituted FAE the γ and δ induced hydroxyl shifts for thecis double bond resonances are +3.08 and −4.63 ppm, respectively while thetrans double bond parameters are +4.06 and −4.18 ppm, respectively. The double bond resonance separation in homoallylic hydroxy fatty acid esters (HAHFA) can be calculated from the formula [|7.71−|Δδdbu‖] forcis and [|8.24−|Δδdbu‖] for thetrans case when the OH substitution is on the carboxyl side of the double bond. Conversely, when the OH resides on the terminal methyl side, the double bond shift separations forcis andtrans isomers are [|7.71+|Δδdbu‖] and [|8.24+|Δδdbu‖], respectively. The derived shift parameters can verify the positions of both the double bond and hydroxyl substitution from the olefinic resonance separation in long‐chain fatty acid derivatives, obviating the need for destructive analytical methods.
Effect of 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase inhibition on human gut mucosa
Authors: Gebhard Roger L. , Ewing Stephen L. , Schlasner Linda A. , Hunninghake Donald B. , Prigge William F.
Published: November 2006

Mevalonic acid is an important biochemical intermediate in cholesterol synthesis and other processes involved in cell replication. 3‐Hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase is the enzyme which catalyzes mevalonic acid synthesis. To determine whether a potent competitive inhibitor of this enzyme, the drug simvastatin, may have an adverse effect on enterocyte cell replication and cholesterol metabolism, small intestinal biopsies from nine hypercholesterolemic subjects were obtained before and during treatment with simvastatin as a lipid‐lowering agent. Histologic review of biopsies in a blinded manner detected no change in ratio of villous length to crypt length or in mitotic index which might indicate altered cell replication. Similarly, no significant change in measured activity of HMG‐CoA reductase activity was observed. In spite of the high exposure of jejunal mucosal cells to this potent competitive inhibitor of a key enzyme, no adverse effect on growth could be detected.
The essential oil fromTagetes minuta L. modulates the binding of [3H]flunitrazepam to crude membranes from chick brain
Authors: García Daniel A. , Perillo María A. , Zygadlo Julio A. , Martijena Irene D.
Published: November 2006

The hypothesis that the essential oil fromTagetes minuta L. can interact with biological membranes was investigated by assessing its ability of perturbing the binding of a benzodiazepine [flunitrazepam (FNTZ)] to crude membranes from chick brains. The essential oil fromT. minuta L. inhibited [3H]FNTZ specific binding to chick brain membranes. These values were obtained from the analysis of the saturation curve for the kinetic parameters: dissociation equilibrium constant (Kd)=2.47±0.32 nM, maximal binding (Bmax)=556±5 fmoles/mg protein, and Hill coefficient (n)=1.00±0.07 in the absence, and Kd=6.73±1.4 nM, Bmax=583±69 fmoles/mg protein, and n=1.02±0.08 in the presence of 29 μg/mL of essential oil. The essential oil could self‐aggregate with a critical micellar concentration (CMC) of 60 μg/mL. The marked increase in [3H]FNTZ nonspecific binding starting at 60 μg of essence per mL was due to that phenomenon and revealed the ability of self‐aggregated structures to interact with membranes. [3H]FNTZ specific binding decrement as a function of essence concentration cannot be ascribed merely to oil's micelles ability of trapping the lipophilic radioligand molecules, because the discontinuous behavior that characterizes a monomer‐aggregate phase transition was not shown. Oil's components might behave as competitive inhibitors or allosteric modulators of FNTZ specific binding. However, their ability to increase FNTZ nonspecific binding at concentrations below oil's CMC suggests that this effect may be due to oil's partitioning into the lipid bilayer. This latter phenomenon would induce an increment in membrane fluidity and a change on FNTZ binding site toward a lower affinity conformation. Therefore, the essential oil components can interact with brain membranes either as monomers, by partitioning into the lipid bilayer, or as self‐aggregated structures, through an adsorption to the membrane surface.
Metabolism of long‐chain fatty acids, alcohols and alkylglycerols in the fish parasiteParatenuisentis ambiguus (Acanthocephala)
Authors: Filipponi Christin , Taraschewski Horst , Weber Nikolaus
Published: November 2006

Specific differences between the acyl composition of lipids on the helminthParatenuisentis ambiguus and its host eel, as shown previously, prompted us to study the lipid metabolism in this intestinal fish parasite. Adults and larvae ofP. ambiguus were fed various lipid precursors, e.g., fatty acids, long‐chain alcohols and 1‐O‐alkylglycerols, which may occur as common nutrients of intestinal parasites. Incorporation of [1‐14C]palmitic acid into neutral and polar lipids was found to be similar under aerobic and near‐anaerobic conditions. In adult parasites maintained in culture medium supplemented with glucose, [1‐14C]palmitic acid was incorporated mainly into triacylglycerols and phosphatidylcholines, whereas [1‐14C]oleic acid was incorporated preferentially into triacylglycerols. In fasted adults, as well as in larvae, [1‐14C]oleic acid was mainly transferred to phosphatidylcholines. Lipolytic activity was detected in adult parasites that had been incubated with radioactive trioleoylglycerol. [1‐14C]Hexadecan‐1‐ol was oxidized inP. ambiguus at a high rate to labeled palmitic acid, which was incorporated into various lipid classes ofP. ambiguus. Small but significant proportions of radioactivity from hexadecan‐1‐ol were incorporated into ether glycerolipids of the parasite. A more direct precursor in ether glycerolipid metabolism, i.e.,rac‐1‐O‐[1′‐14C] hexadecylglycerol, was incorporated into alkyl and 1′‐alkenyl moieties of choline and etha‐nolamine etherglycerophospholipids ofP. ambiguus in high yield. High proportions of labeled diacylglycerols, triacylglycerols and steryl esters were detected in surface lipids as well as lipid extracts of the culture media after incubation ofP. ambiguus with [1‐14C]palmitic or [1‐14C]oleic acids. The results suggest that palmitic acid and oleic acid are incorporated into neutral and polar lipids ofP. ambiguus maintained in glucose medium quite differently with oleic acid showing a strong preference for triacylglycerols. However, the incorporation of palmitic acid in glucose‐fed parasites was similar to that of oleic acid in fasted parasites, as well as in larvae. This may be explained by partial fatty acid depletion in fasted worms and rapid cell division in larvae, respectively.
An improved spectrophotometric triiodide assay for lipid hydroperoxides
Authors: Darrow Robert A. , Organisciak Daniel T.
Published: November 2006

A spectrophotometric method is described for the measurement of lipid hydroperoxides, to a lower limit of 0.5 nmoles, based on the formation of triiodide ions measured at the absorbance maximum of 365 nm. The assay mixture, which was modified from an earlier published procedure [El‐Saadani, M., Esterbauer, H., El‐Sayed, M., Goher, M., Nassar, A.Y., and Jürgens, G. (1989)J. Lipid Res. 30, 627–630], contains 18% methanol together with nonionic and cationic detergents, and is designed so that the hydroperoxides to be measured can be added in either water or methanol. By incubating the reaction mixture at 50°C for 30 min, less‐reactive hydroperoxides can be measured with the same fidelity as more‐reactive ones. Under these conditions, the assay can be carried out under ordinary room lighting and without special protection from ambient oxygen with absorbance values being stable up to 15 h. Enzymatic standardizations showed that the triiodide method gave comparable results for H2O2, cumene hydroperoxide, linoleic acid hydroperoxide, phosphatidylcholine hydroperoxide, and a photooxidized tissue extract containing a mixture of hydroperoxides. The triiodide assay is recommended primarily for measuring purified hydroperoxides.
Antagonism of [3H]fatty acid incorporation into vimentin by sodium pyruvate: Pitfalls of protein acylation
Authors: Cenedella Richard J. , Mitchell Jeanne
Published: November 2006

In the course of studying possible fatty acid acylation of vimentin by cultured bovine lens epithelial cells, several potential pitfalls of protein‐fatty acid acylation were recognized. Even exhaustive delipidation of vimentin with organic solvents failed to remove all noncovalently associated [3H]palmitate and [3H]myristate. Hydroxylamine treatment of vimentin, separated by sodium dodecylsulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE), failed to remove either palmitate or myristate derived radiolabel. Hydroxylamine treatment did remove palmitate label from a group of lower molecular weight proteins. The myristate radiolabel associated with vimentin recovered after SDS‐PAGE and subjected to acid hydrolysis was shown due to incorporated [3H]amino acids, mainly glutamic acid, generated from the fatty acid. Adding excess sodium pyruvate to labeling media has been used by others to reduce the metabolic conversion of fatty acids to amino acids; however, no direct evidence in support of this antagonism was presented. We observed that inclusion of sodium pyruvate at between 5 and 20 mM in the labeling medium produced a dramatic decrease in incorporation of myristic acid radiolabel into vimentin. However, inclusion of even 20 mM pyruvate did not completely antagonize the metabolic conversion of fatty acid label to amino acids. Furthermore, the sodium pyruvate antagonism could be totally obscured if the exposure of X‐ray film by fluorography was even slightly prolonged. The results illustrate the danger in assuming that solvent extraction totally delipidates proteins and that adding sodium pyruvate to labeling media prevents the transfer of fatty acid label to amino acids. Caution is necessary to conclude that radiolabel associated with specific proteins following incubation of cells with labeled fatty acid is due to covalent attachment of the fatty acid to the protein.
Alteration in membrane lipid order and composition in metabolically hyperactive fatty rat adipocytes
Authors: Guerre‐Millo Michèle , Guesnet Phillipe , Guichard Colette , Durand Georges , Lavau Marcelle
Published: November 2006

We have previously shown that adipose cells from young genetically obese Zucker rats are characterized by very high metabolic activity together with an increase in a wide range of membrane‐mediated functions. The aim of the present study was to examine whether the physical properties of the membranes and the composition of the membrane lipids were altered in these cells. Plasma membranes and two intracellular membrane fractions were prepared by differential ultracentrifugation from inguinal adipose cells of 30‐day‐old obese (fa/fa) and lean (Fa/fa) littermates. The lipid order as measured by steady‐state fluorescence polarization of diphenylhexatriene used as probe was markedly decreased in the plasma membranes of obese rat adipose cells. Consistent with this, the cholesterol‐to‐phospholipid ratio was significantly decreased, and the degree of unsaturation of the phospholipid fatty acids was significantly increased. In intracellular membranes, none of these parameters were altered by the different genotype. In fat cells from obese rats, both plasma and intracellular membranes exhibited a 2‐fold decrease in the ratios of n−6/n−3 fatty acids mainly due to an enrichment in docosahexaenoic acid (22∶6n−3). The data show that the fatty genotype is a determinant of membrane lipid order and composition in adipose cells. The alterations reported here for young obese Zucker rat adipocytes might be related to the metabolic hyperactivity of these cells.
Synthesis and structural analysis of stereospecific 3,4,5‐trisubstituted γ‐butyrolactone phospholipids
Authors: Li Xun , Rotella David P.
Published: November 2006

The first synthesis of stereospecific 3,4,5‐trisubstituted γ‐butyrolactone phospholipids has been achieved by a ten‐step sequence starting fromN,N‐dimethylacetamide (9). Alkylation of 9 with 1‐bromohexane gaveN,N‐dimethyloctanamide (11), which was subjected to aldol condensation with acrolein and afforded theerythro‐N,N‐dimethyl‐3‐hydroxy‐2‐hexyl‐4‐pentenamide (6) and itsthreo isomer 7, both of which were subsequently converted to the corresponding 3‐oxy(hexanoyl) esters 15 and 16. Stereospecific cyclization of diastereomeric allylic amides (6,7,15 and 16)via iodolactonization gave 3,4,5‐trisubstituted γ‐butyrolactones (19–25) in satisfactory yields (68–89%) and with high stereoselectivity (at least 6∶1), except for thethreo amide 16 (2∶1). Conversion of the 6‐iodo‐group of the major iodolactones 23 and 24 to the corresponding 6‐hydroxy lactones 31 and 32 through a wet Prévost reaction also resulted in 4‐hydroxy lactones 30 and 33, and a mechanism for this reaction is proposed. Further phosphorylation of 4‐ or 6‐hydroxy lactones 30, 31 and 32 with diphenyl chlorophosphate gave the corresponding diphenyl phosphoric acid lactone esters 34, 35 and 36, whereas 33 underwent an elimination reaction under formation of a C(3)−C(4) double bond. Hydrogenolysis of the diphenyl groups of esters 34, 35 and 36 over Adams' catalyst [platinum(IV) oxide] yielded the corresponding phosphoric acid lactone esters 38, 39 and 40, which were finally treated with choline tetraphenylborate to afford the desired lactone phospholipids 41, 42 and 43 in overall yields of 9, 30 and 18%, respectively. The structures of all new compounds were unambiguously assigned by analysis of their1H and13C one‐dimensional and two‐dimensional nuclear magnetic resonance (NMR) spectra obtained on a 300 MHz NMR spectrometer, and the structures were confirmed by low or high resolution mass spectrometry as well as elemental analysis. The stereoisomeric purity of the final products (98.2, 99.0 and 98.5% for 41, 42 and 43, respectively) was determined by high‐performance liquid chromatography.
Comparison of the fatty acids of the tunicateBotryllus schlosseri from the Black Sea with two associated bacterial strains
Authors: Carballeira Néstor M. , Shalabi Fathi , Stefanov Kamen , Dimitrov Krassimir , Popov Simeon , Kujumgiev Athanas , Andreev Stoitze
Published: November 2006

The fatty acid composition of the tunicateBotryllus schlosseri and of two bacterial strains found within the tunicate, namelyVibrio parahaemolyticus and of an associated but previously unreported gram positive cocci were studied. The polyunsaturated fatty acids 6,9,12‐octadecatrienoic acid, 5,8,11,14,17‐eicosapentaenoic acid, and 4,7,10,13,16,19‐docosahexaenoic acid were particularly abundant inB. schlosseri and were not detected in the two bacterial strains found in the tunicate. Theiso/anteiso pair, 13‐methyltetradecanoic acid and 12‐methyltetradecanoic acid, were the principal fatty acids in the gram positive cocci, and the 9‐ and 11‐hexadecenoic acids were particulary abundant inV. parahaemolyticus. The diunsaturated fatty acid 9,12‐octadecadienoic acid was also shown to be present inV. parahaemolyticus. The fatty acid composition of a third bacterial strain, characterized as either aPseudomonas or anAlteromonas species, and shown to be present only in the sea water from the Black Sea and not inB. schlosseri, is also reported. This is the first investigation on fatty acids from Black Sea bacteria.
The glycosylceramides of the nematodeCaenorhabditis elegans contain an unusual, branched‐chain sphingoid base
Authors: Chitwood David J. , Lusby William R. , Thompson Malcolm J. , Kochansky Jan P. , Howarth Oliver W.
Published: November 2006

Caenorhabditis elegans was cultured in semi‐defined medium containing yeast extract, soy peptone, glucose, hemoglobin, Tween 80, and sitosterol. Monoglycosylceramides were chromatographically purified from nematode extracts. Their structures were elucidated with mass spectrometry, nuclear magnetic resonance spectroscopy, and analysis of methanolysis products of the parent cerebrosides. The glycosylceramides were unusual in that the only long‐chain sphingoid base detected was aniso‐branched compound with a C‐4 double bond (i.e., 15‐methyl‐2‐aminohexadec‐4‐en‐1,3‐diol). Glucose was the only sugar moiety detected. The fatty acids consisted of a series of primarily straint‐chain, saturated, 2‐hydroxylated C20–C26 acids; someiso‐branched analogs also occurred. The sphingomyelins ofC. elegans were also hydrolyzed, and the sameiso‐branched C17 compound was the only sphingoid base detected. This is the first structural analysis of a nematode glycosphingolipid and the first report of an organism in which the long‐chain sphingoid bases are entirelyiso‐branched.
Studies on linoleic acid 8R‐dioxygenase and hydroperoxide isomerase of the fungusGaeumannomyces graminis
Authors: Su Chao , Brodowsky Irene D. , Oliw Ernst H.
Published: November 2006

Linoleic acid is sequentially converted to7S,8S‐dihydroxy‐9Z,12Z‐octadecadienoic acid by the 8R‐dioxygenase and hydroperoxide isomerase of the fungusGaeumannomyces graminis, which is a common pathogen of wheat. The objective of this study was to separate and characterize the two enzyme activities. The isomerase activity was found mainly in the microsomal fraction of the mycelia and the 8R‐dioxygenase in the cytosol. The 8R‐dioxygenase could be partially purified by ammonium sulfate precipitation, gel filtration, ion exchange chromatography or isoelectric focusing. The 8R‐dioxygenase was unstable during purification, but it could be stabilized by glutathione, glutathione peroxidase and ethylenediaminetetraacetic acid. Several protease inhibitors reduced the enzyme activity. Gel filtration with Sephacryl S‐300 showed that most 8R‐dioxygenase activity was eluted with the front with little retention. Isoelectric focusing in the presence of ethylene glycol (20%) indicated an isoelectric point of pl 6.1–6.3. The enzyme was retained on strong anion exchange columns at pH 7.4 and could be eluted with 0.3–0.5 M NaCl. Incubation of the enzyme with 0.1 mM linoleic acid led to partial inactivation, which may indicate product inhibition. Paracetamol and the lipoxygenase inhibitor ICI 230,487 at 30 μM inhibited the 8R‐dioxygenase by 44 and 58%, respectively. 8R‐hydroperoxy‐9Z,12Z‐octadecadienoic acid was isolated from incubations of linoleic acid with the partially purified enzyme or with the cytosol in the presence ofp‐hydroxymercuribenzoate. The hydroperoxide was rapidly converted by the hydroperoxide isomerase in the microsomal fractions to7S,8S‐dihydroxy‐9Z,12Z‐octadecadienoic acid. The isomerase was neither inhibited by carbon monoxide nor by ketoconazole (100 μM). The isomerase was active over a broad pH range. It could be separated from the 8R‐dioxygenase by differential centrifugation, by ammonium sulfate precipitation and by gel filtration. We conclude that the linoleic acid 8R‐dioxygenase and the hydroperoxide isomerase are two separate enzymes.
Nitric oxide, an inhibitor of lipid oxidation by lipoxygenase, cyclooxygenase and hemoglobin
Authors: Kanner Joseph , Harel Stela , Granit Rina
Published: November 2006

The present study demonstrated that nitric oxide, which is an important mammalian metabolite, can inhibit oxidation by lipoxygenase, cyclooxygenase and hemoglobin. The inhibition is manifested as a lag‐phase that is reversible. The inhibitory effect of nitric oxide on lipoxygenase and cyclooxygenase seems to derive from i) the capability of ·NO to reduce the ferric enzyme to the ferrous form, which is inactive; ii) competition for the iron site available for exogenous ligands; and iii) the radical scavenging ability of the nitroxide radical. Nitric oxide may act as a modulator of the arachidonic acid cascade and in the generation of oxygen‐active species.
Effect of propylthiouracil‐induced hypothyroidism on membranes of adult rat brain
Authors: Salvati S. , Campeggi L. Malvezzi , Sorcini M. , Olivieri A. , Di Biase A.
Published: November 2006

The effect of hypothyroidism on the lipid composition of myelin and synaptosomes isolated from adult rat brain was investigated. The animals were made hypothyroid by adding 0.05% propyl‐2‐thiouracil to their drinking water for four weeks. This pathological state resulted in a significant increase in the relative percentage of choline glycerophospholipids in synaptosomes with a concomitant decrease in ethanolamine glycerophospholipids as compared to controls. In myelin, hypothyroidism significantly influenced only the relative percentage of sulfatides. The effect of the hypothyroid state on mature brain was also reflected in changes in the membrane fatty acid composition. Myelin and synaptosomes showed an increase in arachidonic (20∶4) and eicosatrienoic (20∶3) acids and an increase in the fatty acid unsaturation index. Furthermore, the 20∶4/20∶3 and 20∶3/18∶2 ratios were lower and higher, respectively, in treated animals. The data indicate that hypothyroidism affects the lipid composition of synaptosomes and myelin even though the effects were less pronounced in myelin. The lipid changes observed in hypothyroidism may be of physiological significance, as it is well known that lipid composition modulates various membrane‐bound enzymes, transporters and receptors.
Action of the new hypolipidemic agent lifibrol (K12.148) on lipid homeostasis in normal rats: Plasma lipids, hepatic sterologenesis, and the fate of injected [14C] acetate
Authors: Bell Frank P. , St. John Lori C.
Published: November 2006

Lifibrol, a new hypocholesterolemic agent with activity in humans, was examined in normal rats for its short‐term and long‐term effects on lipid homeostasis. Cholesterol (Chol) synthesis inhibition by lifibrol was demonstratedin vitro in liver minces from normal rats by following [1‐14C]acetate ([14C]Ac) and DL‐[2‐14C]mevalonate ([14C]‐MVA) incorporation into [14C]Chol. When administered at 50 mg/kg/d, lifibrol reduced plasma total Chol and triglycerides (TG) (P<0.001) within 24 h. The Chol reduction was largely a result of reduction of low density and very low density lipoprotein cholesterol (LDL+VLDL‐chol) and a smaller decrease in high density lipoprotein cholesterol (HDL‐chol). After 10 d, however, a rebound effect emerged, and after 41 d, plasma Chol, LDL+VLDL‐chol, and HDL‐chol were restored. In contrast, plasma TG remained at reduced levels (P<0.01). The rebound is attributed to counter‐regulation of hepatic sterologenesis that was assessed bothex vivo andin vivo. Theex vivo incorporation of [14C]MVA and [14C]octanoate into [14C]Chol and total digitonin‐precipitable [14C]sterols ([14C]DPS) in liver minces was increased 2‐and 6‐fold, respectively, in rats treated 6 d at 50 mg/kg. Similarly,in vivo incorporation of intraperitoneally injected [14C]Ac into hepatic [14C]DPS (2 h post‐injection) was increased 2‐ to 5‐fold at 50 mg/kg, and evidence for increased sterologenesis in nonhepatic tissue was also obtained. The increased hepatic sterologenesis, evident within 48 h, persisted out to 41 d of treatment by which time increases (P<0.002) in hepatic Chol and carcass total sterols were observed. Additionally, incorporation of injected [14C]Ac into hepatic [14C]TG was inhibited 60% by lifibrol (P<0.001), and the appearance of [14C]TG in plasma was reduced. Circulating free [14C]fatty acids ([14C]FFA) were also reduced, but hepatic [14C]FFA synthesis was unaffected, thus suggesting either a lesser release of newly formed FFA from liver or an enhanced removal from plasma.
Leukotriene B4 promotes phospholipid acylation in human neutrophils
Authors: Tou Jen‐sie , Healey Sean
Published: November 2006

The present study was undertaken to test the hypothesis that leukotriene B4 (LTB4) may promote extracellular fatty acid incorporation into neutrophil choline glycerophospholipids (PC) to replenish phospholipids after deacylation. Incubation of human neutrophils with LTB4 (1.5 to 150 nM) for 1 for 5 min resulted in increased fatty acid incorporation into phosphatidylinositol (PI), diacyl‐sn‐glycero‐3‐phosphocholine (diacyl‐GPC) and alkylacyl‐GPC. The magnitude of stimulation (percentage of control) of fatty acid incorporation appears to reflect increased activity of the acyltransferases catalyzing acylation of the respective lysophospholipids. LTB4 stimulation of arachidonic acid incorporation into PI was greater than into PC, whereas the stimulation of palmitic acid but not by arachidonic acid. LTB4 and 1‐O‐alkyl‐2‐N‐methylcarbamyl‐sn‐glycero‐3‐phosphocholine (cPAF) exhibited a similar stimulatory effect on fatty acid incorporation into the PC fraction. Phosphate analysis could not detect changes in the mass of PI or of PC in neutrophils exposed to LTB4 or cPAF. The results suggest that increased fatty acid incorporation into phospholipids in LTB4‐activated neutrophils reflects activation of phospholipase A2 and acyltransferases as well as ofde novo phospholipid synthesis.
Transfer of arachidonate from phosphatidylcholine to phosphatidylethanolamine and triacylglycerol in guinea pig alveolar macrophages
Authors: Nijssen J. G. , Oosting R. S. , Nÿkamp F. P. , van den Bosch H.
Published: November 2006

Guinea pig alveolar macrophages were labeled by incubation with either arachidonate or linoleate. Arachidonate labeled phosphatidylcholine (PC), phosphatidylethanolamine (PE) and triglycerides (TG) equally well, with each lipid containing about 30% of total cellular radioactivity. In comparison to arachidonate, linoleate was recovered significantly less in PE (7%) and more in TG (47%). To investigate whether redistributions of acyl chains among lipid classes took place, the macrophages were incubated with 1‐acyl‐2‐[1‐14C]arachidonoyl PC or 1‐acyl‐2‐[1‐14C]linoleoyl PC. After harvesting, the cells incubated with 1‐acyl‐2‐[1‐14C]linoleoyl PC contained 86% of the recovered cellular radioactivity in PC, with only small amounts of label being transferred to PE and TG (3 and 6%, respectively). More extensive redistributions were observed with arachidonate‐labeled PC. In this case, only 60% of cellular radioactivity was still associated with PC, while 22 and 12%, respectively, had been transferred to PE and TG. Arachidonate transfer from PC to PE was unaffected by an excess of free arachidonate which inhibited this transfer to TG for over 90%, indicating that different mechanisms or arachidonoyl CoA pools were involved in the transfer of arachidonate from PC to PE and TG. Cells prelabeled with 1‐acyl‐2‐[1‐14C]arachidonoyl PC released14C‐label into the medium upon further incubation. This release was slightly stimulated by zymosan and threefold higher in the presence of the Ca2+‐ionophore A23187. Labeling of macrophages with intact phospholipid molecules appears to be a suitable method for studying acyl chain redistribution and release reactions.
Phosphorylation of lipids in rat primary glial cells and immortalized astrocytes (DITNC)
Authors: Tong Wei , Sun Grace Y.
Published: November 2006

Phosphatidylinositol 4,5‐bisphosphate, a substrate in the signal transduction pathway involving phospholipase C, is synthesized in cell membranes by phosphorylation of phosphatidylinositol (PI) and phosphatidylinositol 4‐phosphate (PI‐4‐P). Incubation with [γ‐32P]adenosine triphosphate of membranes isolated from primary glial cells in culture and from an immortalized astrocyte cell line (DITNC) and subsequent separation of the lipids by high‐performance thin‐layer chromatography revealed a number of labeled lipid bands. Further analysis of the deacylated products by high‐performance liquid chromatography indicated the presence of two PI‐4‐P bands and a band corresponding to lysoPIP (PIP, PI phosphate). The two PI‐4‐P bands were more prominent in the samples from astrocyte cell membranes than from synaptic plasma membranes and plasma membranes. Analysis of the fatty acid composition of PI by gas‐liquid chromatography revealed that both 20∶3n−9 and 20∶4n−6 were present in PI of cultured cell membranes, whereas the brain membranes contained exclusively 20∶4n−6. The two PI‐4‐P bands in these membranes can be attributed to the presence of different molecular species of PI. Assignment of the fraction corresponding to lysoPIP was consistent with the observation that an increase in label in this lipid band occurred upon incubation of DITNC cell supernatant with lysoPI (1‐stearoyl PI). This suggests that endogenous lysoPI present in the cell membranes can be phosphorylated to form lysoPIP.
The effect of lidocaine onde novo phospholipid biosynthesis in the isolated hamster heart
Authors: Wong Jason T. , Man Ricky Y. K. , Choy Patric C.
Published: November 2006

Lidocaine is used clinically as an antiarrhythmic agent, but its effect on cardiac phospholipid metabolism has not been defined. In this study, hamster hearts were perfused with [1,3‐3H]glycerol in the presence of 0.5 mg/mL lidocaine. The incorporation of radioactivities into lysophosphatidic acid, phosphatidic acid, phosphatidylethanolamine, cytidine diphosphate diacylglycerol, phosphatidylinositol, phosphatidylserine, diacylglycerol and triacylglycerol were enhanced by lidocaine treatment, whereas the labelling of phosphatidylcholine was reduced. Analyses of enzyme activities in the heart after perfusion with lidocaine revealed that the activities of phosphatidate phosphatase and acyl‐coenzyme A (CoA):1,2‐diacylglycerol acyltransferase were enhanced. The presence of lidocaine in the assay did not directly stimulate these enzymes. However, the activity of acyl‐CoA:glycerol‐3‐phosphate acyltransferase was stimulated by lidocaine whereas the activity of cytidine diphosphocholine:1,2‐diacylglycerol cholinephosphotransferase was inhibited by lidocaine. We conclude that lidocaine affects the regulation of phospholipid biosynthesis in the heart by both direct and indirect modulation of phospholipid biosynthetic enzymes.
High density lipoproteins from bovine plasma and follicular fluid do not possess a high affinity for glycosaminoglycans
Authors: Brantmeier S. A. , Grummer R. R. , Ax R. L.
Published: November 2006

Possible interactions between glycosaminoglycans and high density lipoproteins (HDL) in plasma and follicular fluid were examined. Total lipoproteins (d<1.21 g/ml) were obtained from plasma of five Holstein cows by ultracentrifugation and fractionated by gel filtration. Every other fraction from the HDL peak or fractions corresponding to the base and ascending portion of the HDL peak were composited and applied to a heparin‐Sepharose affinity chromatography column. Elution profiles from both composites showed a peak that did not bind to the column that contained HDL devoid of apolipoprotein‐E as determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and silver staining and immunoblot analysis. Elution of lipoproteins from the ascending portion of the HDL peak resulted in a second minor peak eluting at 0.35 M NaCl, which was low density lipoprotein (LDL) contamination. Lipoproteins (d<1.21g/ml) isolated from follicular fluid obtained from small, medium or large follicles also were subjected to heparin‐Sepharose affinity chromatography. Two peaks were observed, one corresponding to the lipoprotein that did not bind to the column, the other eluted at 0.5M NaCl and accounted for less than 2% of the protein applied. The second peak did not contain apolipoprotein‐E or LDL. Bovine follicular fluid glycosaminoglycans (GAG) were isolated and subjected to HDL‐Sepharose affinity chromatography. Less than 2% of the total GAG bound to the HDL column. Therefore, HDL in bovine specimens did not interact appreciably with heparin or GAG isolated from follicular fluid.
Effects of relative humidity on lipid autoxidation in a model system
Authors: Kahl J. L. , Artz W. E. , Schanus E. G.
Published: November 2006

A new model system was developed for the study of autoxidation of thin films of neat lipid and the effect of relative humidity on the oxidation reaction. In the model system, the surface‐to‐volume ratio of lipid was large and measureable, and the relative humidity (RH) and oxygen partial pressure were controlled. Methyl linoleate, oxidized at six different RH as a thin film in an atmosphere of pure oxygen, exhibited a maximum rate of oxidation at 32% RH and minimum rates at 0% and 100% RH. The rates of oxygen uptake, determined manometrically, were linear and reproducible at all six RH. The maximum rate at 32% RH was attributed to solvation and stabilization of the propagation transition state by water. Increasing the RH beyond 32% resulted in solvation of the peroxy radical, sterically hindering the radical from entering the propagation transition state.
Preparation of methylcis‐9,cis‐12,cis‐15‐octadecatrienoate‐15,16‐d2 and methylcis‐9,cis‐12,cis‐15‐octadecatrienoate‐6,6,7,7‐d4
Authors: Rakoff Henry
Published: November 2006

Methylcis‐9,cis‐12,cis‐15‐octadecatrienoate‐15,16‐d2 was obtained from Wittig coupling of methyl 12‐oxo‐cis‐9‐dodecenoate,18, and 3,4‐dideutero‐cis‐3‐hexenyltriphenylphosphonium bromide,16. Compound18 was obtained by periodic acid oxidation of methyl 12,13‐dihydroxy‐cis‐9‐octadecenoate,17, obtained fromVernonia oil. Compound18 also was synthesized from methyl oleate as the starting material. The deuterated fragment,16, was prepared from 3‐hexynol and using Lindlar's catalyst and deuterium gas to introduce the deuterium atoms.

Methylcis‐9,cis‐12,cis‐15‐octadecatrienoate‐6,6,7,7‐d4 was prepared by Wittig coupling of 3,6‐nonadienyltriphenylphosphonium iodide,5, with methyl 9‐oxononanoate‐6,6,7,7‐d4,11. Deuterium atoms were introduced during the synthesis of11 from 3‐butynol and 5‐bromopentanoic acid with deuterium gas in the presence of [Ph3P]3‐RhCl. For the preparation of5, the 3,6‐nonadiynol intermediate was reduced to 3,6‐nonadienol with P‐2 Nickel and hydrogen.

The final products were separated from isomers formed during the synthetic sequences by silver resin chromatography.
Effect of essential fatty acid deficiency on myelin proteins
Authors: Miller Sheldon L. , Klurfeld David M. , Loftus Bernadette , Kritchevsky David
Published: November 2006

The effect of essential fatty acid (EFA) deficiency on rat‐brain myelin proteins was studied. Rats were maintained on a lipid‐free diet and compared with control rats fed the same diet supplemented with 3% corn oil. At 17 days of age, each pup was injected with [3H]leucine and rats from each group were killed over a period of 163 days. Although a large decrease occurred in the total amount of myelin protein per brain, the proportions of constituent myelin proteins remained relatively unchanged. Metabolic studies showed a decrease in the net turnover of myelin proteins analogous to that previously demonstrated for myelin phospholipid (PL).