bluuebunny/crossref_metadata_2025 huggingface dataset:
Reversible or irreversible modification of [3H]PAF binding on rabbit platelet membranes differentiates various PAF receptor antagonists
Authors: Domingo M. T. , Piro F. , Broquet C. , Auclair E. , Chabrier P. E. , Braquet P.
Published: November 2006

[3H]Platelet‐activating factor (PAF) binding to rabbit platelet membranes was examined before and after 20 min preincubation at 25°C in the presence of PAF, lysoPAF, or of five different PAF receptor antagonists (L 652731, BN 52021, WEB 2086, BN 52111 and BN 52115). When platelet membranes were not washed after preincubation with PAF or PAF antagonists, no significant specific binding of [3H]PAF was observed, which suggests full occupancy of the binding sites. When membranes were extensively washed, full recovery of specific [3H]PAF binding was attained with L 652731 and partial recoveries (60%, 55% and 30%) were reached with BN52021, WEB 2086 and PAF, respectively; no recovery was seen with the dioxolanes BN 52111 and BN 52115. Scatchard analysis of the binding data indicated that no significant change in the dissociation constant (Kd) and maximum number of binding sites (Bmax) occurred after preincubation of platelet membrane with L 652731, whereas a reduction of Bmax was observed when PAF and BN 52021 were measured. When platelet membranes were preincubated with WEB 2086, Bmax and Kd significantly increased. The data suggest differing binding properties for PAF and the PAF antagonists. Some of the PAF antagonists may tightly bind to the PAF receptor site(s) and/or irreversibly modify or downregulate PAF recognition sites. Our results also suggest that the interaction of PAF receptor antagonists with PAF receptor can be divided into at least two components, namely a reversible component and an irreversible one.
The origin of palmitic acid in brain of the developing rat
Authors: Marbois B. Noelle , Ajie Henry O. , Korsak Rose A. , Sensharma Dilip K. , Edmond John
Published: November 2006

A rat milk substitute containing lower amounts of palmitic and oleic acid in the triacylglycerols in comparison to natural rat milk was fed to artificially reared rat pups from day 7 after birth to day 14. Pups reared by their mother served as controls. Free trideuterated (D3) palmitic acid [(C2H3)(CH2)14COOH, 98 atom % D] and free perdeuterated (D31) palmitic acid [C152H31COOH, 99 atom % D] in equal quantity were mixed into the triacylglycerols of the milk substitute in an amount equal to 100% of the palmitic acid in the triacylglycerols. A control milk substitute contained unlabeled free palmitic acid in an amount equal to 100% of the palmitic acid in the triacylglycerols of the milk substitute. The objective was to determine if palmitic acid in the diet contributed significantly to the palmitic acid content of developing brain and other organs. The methyl esters of the fatty acids were analyzed by gas chromatography and the palmitic acid methyl ester was examined by fast atom bombardment mass spectrometry. The proportion of deuterated methyl palmitate as a percentage of total palmitate was determined; 32% of the palmitic acid in liver and 12% of the palmitic acid in lung were trideuterated and perdeuterated palmitic acid in approximately equal amounts. The brain, by contrast, did not contain the deuterated palmitic acid moiety. Quantitation of palmitic acid and total fatty acids revealed a significant accumulation in organs in the interval from 7 to 14 days of age. Under our experimental conditions, labeled palmitic acid does not enter the brain. Consequently, we conclude that the developing brain produces all required palmitic acid byde novo synthesis.
Arachidonic acid biosynthesis in non‐stimulated and adrenocorticotropin‐stimulated sertoli and leydig cells
Authors: Hurtado de Catalfo Graciela E. , Mandon Elisabet C. , de Gómez Dumm Irma N. T.
Published: November 2006

The biosynthesis of arachidonic acid in Sertoli and Leydig cells isolated from the testes of mature rats has been investigated. Both types of cells incorporated [2‐14C]eicosatrienoic acid from the incubation medium and transformed it into arachidonic acid. The administration of adrenocorticotropin (ACTH) to the rats decreased the Δ5 desaturating activity in the isolated testicular cells, while ACTH produced no changes in the uptake of the substrate. Similar results were obtained when ACTH was added to the incubation medium of cells isolated from non‐hormone treated rats. The total fatty acid composition of the Sertoli cells isolated from ACTH‐treated rats showed a significant increase in the relative percentage of 18∶2n−6 and a decrease in the C20 and C22 polyenes. This may indicate that ACTH exerts an inhibitory effect on Δ6, Δ5 and Δ4 desaturase activities. Addition of corticosterone to the incubation medium also produced a significant decrease in arachidonic acid biosynthesis. Because ACTH is known to stimulate the release of corticosteronein vivo, both hormones may act cumulatively in the regulation of arachidonic acid metabolism in Sertoli and Leydig cells.
Effects of various dietary fats on cardiolipin acyl composition during ontogeny of mice
Authors: Berger Alvin , Gershwin M. E. , German J. Bruce
Published: November 2006

Cardiolipin (CL) is a unique mitochondrial phospholipid, containing up to 85 wt% 18∶2n−6 in mammals. The influence of maternal dietary fatty acids on the acyl composition of offspring CL has not been examined previously. Adult female mice were thus fed diets rich in 18∶1n−9 (olive oil), 18∶2n−6 (safflower oil), 18∶3n−3 (linseed oil) or 20∶5n−3 and 22∶6n−3 (fish oil/safflower, 9∶1, w/w), for a five month period, encompassing two breeding cycles. Offspring from the second breeding cycle were then fed these diets. The acyl composition of CL, phosphatidylcholine and phosphatidylethanolamine from liver and heart was evaluated from mice killed 3, 18 and 42 days after parturition. The primary nutrient sources at these three time points were transplacental nutrients, breast milk and the diet, respectively. Maternal diet was found to influence the acyl composition of CLvia both placental transfer of fatty acids and breast milk. Fish oil feeding resulted in replacement of a substantial portion of 18∶2n−6 with 22∶6n−3; after 42 days, the area% of 18∶2n−6 in heart CL was reduced from 62% in safflower oil fed mice to 12%. In comparison to fish oil feeding, linseed oil feeding resulted in a much lower accumulation of 22∶6n−3. Olive oil feeding resulted in substantial replacement of 18∶2n−6 with 18∶1n−9 (18∶2n−6 was reduced from 62% to 31%). Physiologically, these findings are relevant because changes in CL acyl composition may influence the activity of associated inner mitochondrial membrane enzymes.
Surface components of chylomicrons from rats fed glyceryl or alkyl esters of fatty acids: Minor components
Authors: Yang L. Y. , Kuksis A. , Myher J. J. , Pang H.
Published: November 2006

The lipid class, fatty acid and molecular species composition of the minor polar surface components of rat lymph chylomicrons were determined during absorption of menhaden oil and corn oil or of the corresponding fatty acid ethyl esters. In addition to the previously reported minor polar lipids (sphingomyelin, phosphatidylserine, phosphatidylinositol, phosphatidic acid and lysophosphatidylcholine), we identified phosphatidylglycerol, dimethyl‐phosphatidylethanolamine, ceramide and cholesteryl sulfate in the chylomicrons from both oil and ester feeding. The dietary fatty acids were found to be incorporated to a variable extent into the different phospholipid classes, the proportions of which remained the same during both types of feeding. No evidence was obtained for the presence of the minor glycerophospholipids characteristic of the lysosomal membranes (e.g., bis‐phosphatidic, lysobisphosphatidic and semilysobis‐phosphatidic acids), although special efforts were made to identify them. These results indicate that the chylomicrons arising from the monoacylglycerol and phosphatidic acid pathways of triacylglycerol biosynthesis become enveloped in closely similar monolayers of phospholipids. Hence, all triacylglycerols may be secreted from the villus cellsvia a common mechanism as suggested by the previously demonstrated convergence (at the 2‐monoacylglycerol stage) of the monoacylglycerol and the phosphatidic acid pathways of mucosal triacylglycerol formation [Yang, Y.L., and Kuksis, A. (1991)J. Lipid Res. 32, 1173–1186].
Effects of dietary saturated fat on erucic acid induced myocardial lipidosis in rats
Authors: Kramer J. K. G. , Sauer F. D. , Wolynetz M. S. , Farnworth E. R. , Johnston K. M.
Published: November 2006

Male Sprague‐Dawley rats were fed for one week diets containing 20% by weight fat/oil mixtures with different levels of erucic acid (22∶1n−9) (∼2.5 or 9%) and total saturated fatty acids (∼8 or 35%). Corn oil and high erucic acid rapeseed (HEAR) oil were fed as controls. The same hearts were evaluated histologically using oil red O staining and chemically for cardiac triacylglycerol (TAG) and 22∶1n−9 content in cardiac TAG to compare the three methods for assessing lipid accumulation in rat hearts. Rats fed corn oil showed trace myocardial lipidosis by staining, and a cardiac TAG content of 3.6 mg/g wet weight in the absence of dietary 22∶1n−9. An increase in dietary 22∶1n−9 resulted in significantly increased myocardial lipidosis as assessed histologically and by an accumulation of 22∶1n−9 in heart lipids; there was no increase in cardiac TAG except when HEAR oil was fed. An increase in saturated fatty acids showed no changes in myocardial lipid content assessed histologically, the content of cardiac TAG or the 22∶1n−9 content of TAG at either 2.5 or 9% dietary 22∶1n−9. The histological staining method was more significantly correlated to 22∶1n−9 in cardiac TAG (r=0.49;P<0.001) than to total cardiac TAG (r=0.40;P<0.05). The 22∶1n−9 content was highest in cardiac TAG and free fatty acids. Among the cardiac phospholipids, the highest incorporation was observed into phosphatidylserine, followed by sphingomyelin. With the addition of saturated fat, the fatty acid composition showed decreased accumulation of 22∶1n−9 and increased levels of arachidonic and docosahexaenoic acids in most cardiac phospholipids, despite decreased dietary concentrations of their precursor fatty acids, linoleic and linolenic acids.
Comparison of sulfoquinovosyl diacylglycerol from spinach and the purple bacteriumRhodobacter sphaeroides by fast atom bombardment tandem mass spectrometry
Authors: Gage Douglas A. , Huang Zhi‐Heng , Benning Christoph
Published: November 2006

Isolated sulfoquinovosyl‐diacylglycerol (SQD) from spinach and the purple bacteriumRhodobacter sphaeroides provide two sources of very different molecular species of SQD. We were able to demonstrate by fast atom bombardment‐collisionally activated dissociation tandem mass spectrometry in the negative ion mode that the sulfoquinovosyl head group of the plant and bacterial lipids can be characterized by the common fragmentation pattern found in the spectra of both samples. Differences in the acyl functions from the two sources were also identified by this technique. SQD specific fragments are found atm/z 299, 283, 241, 225, 165 and 80 which indicate the presence of the sulfoquinovosyl moiety. The two predominant molecular species found in spinach contain palmitic and linolenic ([M−H]− atm/z 815) or two linolenic acids ([M−H]− atm/z 837) in thesn−1 andsn−2 positions, while the two major species of the bacterial lipid contain palmitic and 18∶1 (vaccenic) cids ([M−H]− atm/z 819) or stearic and 18∶1 (vaccenic) acids, ([M−H]− atm/z 847), respectively.
The fatty acids of the spongeDysidea fragilis from the black sea
Authors: Christie W. W. , Brechany Elizabeth Y. , Stefanov K. , Popov S.
Published: November 2006

The fatty acid composition of the sponge,Dysidea fragilis, from the Black Sea has been determined by analytical gas chromatography, silver ion high‐performance liquid chromatography and gas chromatography/mass spectrometry. More than a hundred different fatty acids were identified, of which many were similar to those in sponges from tropical seas. On the other hand, some of the fatty acids identified have not been found previously in sponges or other marine sources and perhaps are new to science. These include 13‐methyl‐tetradec‐4‐enoic and 14‐methyl‐hexadec‐6‐enoic acids, together with demospongic acids,i.e. 5,9,17‐tetracosatrienoic, 5,9,17‐pentacosatrienoic and 5,9,19‐pentacosatrienoic acids. From the elution behavior on silver nitrate chromatography, all the double bonds were of thecis‐configuration.
Linoleic acid metabolism in the red algaLithothamnion corallioides: Biosynthesis of 11(R)‐hydroxy‐9(Z),12(Z)‐octadecadienoic acid
Authors: Hámberg Mats , Gerwick William H. , Åsen Per Arvid
Published: November 2006

Incubation of [1‐14C]linoleic acid with an enzyme preparation obtained from the red algaLithothamnion corallioidesCrouan resulted in the formation of 11‐hydroxy‐9(Z),12(Z)‐octadecadienoic acid as well as smaller amounts of 9‐hydroxy‐10(E),12(Z)‐octadecadienoic acid, 13‐hydroxy‐9(Z),11(E)‐octadecadienoic acid and 11‐keto‐9(Z),12(Z)‐octadecadienoic acid. Steric analysis showed that the 11‐hydroxyoctadecadienoic acid had the (R) configuration. The 9‐ and 13‐hydroxyoctadecadienoic acids were not optically pure, but were due to mixtures of 75% (R) and 25% (S) enantiomers (9‐hydroxyoctadecadienoate), and 24% (R) and 76% (S) enantiomers (13‐hydroxy‐octadecadienoate). 11‐Hydroxyoctadecadienoic acid was unstable at acidic pH. In acidified water, equal parts of 9(R,S)‐hydroxy‐10(E),12(Z)‐octadecadienoate and 13(R,S)‐hydroxy‐9(Z),11(E)‐octadecadienoate, plus smaller amounts of the corresponding (E),(E) isomers were produced. In aprotic solvents, acid treatment resulted in dehydration and in the formation of equal amounts of 8,10,12‐ and 9,11,13‐octadecatrienoates. The enzymatic conversion of linoleic acid into the hydroxyoctadecadienoic acids and the ketooctadecadienoic acid was oxygen‐dependent; however, inhibitor experiments indicated that neither lipoxygenase nor cytochrome P‐450 were involved in the conversion. This conclusion was supported by experiments with18O2 and H218O, which demonstrated that the hydroxyl oxygen of the hydroxy‐octadecadienoic acids and the keto oxygen of the 11‐ketooctadecadienoic acid were derived from water and not from molecular oxygen.
Metabolism of [1‐14C]docosahexaenoate (22∶6n−3), [1‐14C]eicosapentaenoate (20∶5n−3) and [1‐14C]linolenate (18∶3n−3) in brain cells from juvenile turbotScophthalmus maximus
Authors: Tocher Douglas R. , Mourente Gabriel , Sargent John R.
Published: November 2006

The incorporation of [1‐14C]18∶3n−3, (LNA) and [1‐14C]‐22∶6n−3 (DHA), and the metabolismvia the desaturase/elongase pathways of [1‐14C]LNA, and [1‐14C]20∶5n−3 (EPA) were studied in brain cells from newly‐weaned (1‐month‐old) and 4‐month‐old turbot. The rank order of the extent of net incorporation of both LNA and DHA into glycerophospholipids was total diradyl glycerophosphocholines (CPL)> total diradyl glycerophosphoethanolamines (EPL)> phosphatidylserine (PS) and phosphatidylinositol (PI) and was independent of the polyunsaturated fatty acid added, the age of the fish and the time of incubation. However, the rate of incorporation of LNA into total lipid, CPL, EPL and PS was significantly greater than the rate of incorporation of DHA, and there was a significantly greater amount of DHA incorporated into EPL than LNA. There was no significant difference between the amounts of LNA and DHA incorporated into total lipid, CPL, PS and PI. Therefore, little preferential uptake and incorporation of DHA into brain cells was apparent. In 24‐h incubations, on average 1.1% and 8.5% of radioactivity from [1‐14C]LNA and [1‐14C]EPA, respectively, were recovered in the DHA fraction. Therefore, LNA cannot contribute significantly to brain DHA levels in the turbot but EPA can. There were no significant differences between the amounts of radioactivity from either [1‐14C]LNA or [1‐14C]EPA recovered in the individual products/intermediates of the desaturase pathways in brain cells from 30‐day‐old and 120‐day‐old turbot.
Phospholipid fatty acyl distribution of three fungi indicates positional specificity for n‐6vs. n‐3 fatty acids
Authors: Kendrick Andrew , Ratledge Collin
Published: November 2006

Phospholipids of the fungiConidobolus nanodes, Entomophthora exitalis andSaprolegnia parasitica were extracted and analyzed. The phospholipid content was the same (2.4%) for the three species and was independent of the total lipid content. Phospholipase A2 degradation of individual phospholipid classes showed an asymmetrical distribution of polyunsaturated fatty acids (PUFA) between the two fatty acyl positions of glycerol. There was a predominance of n‐6 PUFA at position 2 and a predominance of n‐3 PUFA at position 1. WithC. nanodes andE. exitalis, 20∶5n−3 is derived from 18∶3n−3 and is located predominantly at position 1. InS. parasitica 20∶5n−3 is synthesized from 18∶3n−6via 20∶4n−6 and is located predominantly at position 2. It is suggested that the asymmetrical distribution of PUFA between positions 1 and 2 of glycerol Points towards different sites of synthesis of the two classes of PUFA, and that cross‐over between PUFA of the different types is prevented by thesn‐1 orsn‐2 positional specificity of the desaturases.
Nonesterified fatty acids in normal and diabetic rat sciatic nerve
Authors: Chattopadhyay Jyotiprakas , Thompson Ed W. , Schmid Harald H. O.
Published: November 2006

Alloxan‐induced diabetes in rats results in elevated levels of nonesterified fatty acids (NEFA) in whole sciatic nerve and its endoneurium. Increases in NEFA levels are more pronounced in whole diabetic nerve (40% over control) than in its endoneurial portion (20–30%). Alterations in the composition of phospholipid fatty acids are observed as well, including an increase in linoleate (18∶2n−6) in endoneurial phosphatidylethanolamine and a decrease in arachidonate (20∶4n−6) in both phosphatidylethanolamine and phosphatidylinositol of diabetic nerve.
Changes in fatty acid composition of plasma and oviduct lipids during sexual maturation of Japanese quail
Authors: Pageaux Jean François , Joulain Catherine , Fayard Jean Michel , Lagarde Michel , Laugier Christian
Published: November 2006

The fatty acid (FA) compositions of plasma and oviduct phospholipids (PL) and triglycerides (TG) were studied throughout the natural sexual development of the Japanese quail. In the oviduct, PL concentration increased rapidly during the period of active oviduct cell proliferation and then remained at a constant level during the phase of cellular hypertrophy. Oviduct and plasma TG concentrations were 2‐ and 10‐fold higher, respectively, in fully developed animals than in immature ones. During natural sexual maturation of the quail, the FA compositions of PL and TG were markedly modified both in plasma and in oviduct. These qualitative changes occurred predominantly during the period of intense cellular proliferation of oviduct cells, and also were observed in immature animals injected with physiological doses of estradiol. In oviduct PL, the proportions of 20∶4n−6 and 22∶4n−6 decreased significantly (from 20 to 10% and 3.5 to 0.7%, respectively) whereas those of 18∶2n−6 increased (from 8.5 to 21%). In contrast, the plasma PL proportions of 20∶4n−6, 22∶4n−6 and 18∶2n−6 were decreased significantly and the percentage of 18∶1n−9 doubled, suggesting that the oviduct is able to utilize certain plasma FA to a greater extent than others. Changes in plasma and oviduct lipid composition occurring in the quail during sexual development may be attributed to estradiol, which stimulates hepatic Δ9 desaturase and inhibits the oviduct Δ6 desaturase. The changes in FA composition observed in oviduct phospholipids are discussed in relation to eicosanoid production and cellular proliferation.
The effect of beta blocking drugs on lipid peroxidation in rat heartin vitro
Authors: Jenkins R. R. , Del Signore C. M. , Sauer P. , Skelly C.
Published: November 2006

Beta‐adrenergic receptor blocking drugs include a structurally related class of drugs that are employed clinically to treat a variety of cardiovascular disorders. Since these drugs exert additional nonspecific effects including membrane stabilization, representative samples including atenolol, dilevolol, labetolol, metoprolol and propranolol were studied to determine their influence on lipid peroxidation. Homogenates or liposomes of adult rat hearts were incubated in the presence of various concentrations of propranolol or equivalent concentrations of dilevolol, labetolol, metoprolol or atenolol. Lipid peroxidation was stimulated with 50 μM FeSO4, 5 μMt‐butyl hydroperoxide (homogenates) or 0.2 mM citrate FeSO4 (liposomes) plus O2. Lipid peroxidation, as assessed by both the thiobarbituric acid reaction and chemiluminescence, was reduced in a dose‐dependent manner as the propranolol concentration was increased from 1 to 10 mM. The five beta‐adrenergic receptor blocking drugs reduced lipid peroxidation both in crude homogenates and in liposomes; their effectiveness was related to their lipophilicity. Dilevolol, propranolol, labetolol and metoprolol at a concentration of 20 mM reduced lipid peroxidation by 45%, 37%, 35% and 28%, respectively. The hydrophilic blocker atenolol was ineffective in reducing lipid peroxidation event at elevated concentrations. Lipophilic beta‐blocking drugs apparently are capable of exerting an antioxidant effect in protecting membrane lipids against peroxidation.
Ascorbate and phenolic antioxidant interactions in prevention of liposomal oxidation
Authors: Thomas Craig E. , McLean Larry R. , Parker Roger A. , Ohlweiler David F.
Published: November 2006

Efficient prevention of membrane lipid peroxidation by vitamin E (α‐tocopherol) may involve its regeneration by vitamin C (ascorbate). Conceivably, the efficacy of antioxidants designed as therapeutic agents could be enhanced if a similar regeneration were favorable; thus, a model membrane system was developed which allowed assessment of interaction of phenolic antioxidants with ascorbate and ascorbyl‐6‐palmitate. Ascorbate alone (50–200 μM) potentiated oxidation of soybean phosphatidylcholine liposomes by Fe2+/histidine‐Fe3+, an effect which was temporally related to reduction of Fe3+ generated during oxidation. Addition of 200 μM ascorbate to α‐tocopherol‐containing liposomes (0.1 mol%) resulted in marked, synergistic protection. Accordingly, in the presence but not absence of ascorbate, α‐tocopherol levels were maintained relatively constant during Fe2+/histidine‐Fe3+ exposure. Probucol (4,4′‐[(1‐methylethylidine)bis(thio)]bis[2,6‐bis(1,1‐dimethylethyl)]phenol), and antioxidant which prevents oxidation of low density lipoproteins, and its analogues MDL 27,968 (4,4′‐[(1‐methylethylidene)bis(thio)]‐bis[2,6‐dimethyl]phenol) and MDL 28,881 (2,6‐bis(1,1‐dimethylethyl)‐4‐[(3,7,11‐trimethyldodecyl)thio]phenol) prevented oxidation but exhibited no synergy with ascorbate. Ascorbyl‐6‐palmitate itself was an effective antioxidant but did not interact synergistically with any of the phenolic antioxidants. Differential scanning calorimetry revealed significant differences among the antioxidants in their effect on the liquid‐crystalline phase transition of dipalmitoyl phosphatidylcholine (DPPC) liposomes. Both α‐tocopherol and MDL 27,968 significantly reduced the phase transition temperature and the enthalpy of the transition. MDL 28,881 had no effect while probucol was intermediate. The potential for ascorbate or its analogues to interact with phenolic antioxidants to provide a more effective antioxidant system appears to be dictated by structural features and by the location of the antioxidants in the membrane.
The determination of tissue ethanolamine levels by reverse‐phase high‐performance liquid chromatography
Authors: McMaster Christopher R. , Choy Patrick C.
Published: November 2006

A rapid and sensitive procedure for the determination of ethanolamine levels in mammalian tissues is reported. Ethanolamine was extracted from the tissue with a chloroform/methanol mixture, followed by phase separation. The aqueous phase was subjected to charcoal chromatography and the lluant was derivatized with phenylisothiocyanate. The amount of phenylthiocarbamyl (PTC) ethanolamine in the tissue extract was determined by reverse‐phase high‐performance liquid chromatography. Quantitation of PTC ethanolamine was linear between 0.1–10 nmol. The pool sizes of ethanolamine in hamster heart, liver and kidney were found to be 1.07, 0.92 and 1.11 μmol/g wet weight, respectively. The sensitivity of the method would allow the determination of ethanolamine in very small tissue samples.
Catalytic deuteration of alkynols and their tetrahydropyranyl ethers
Authors: Rakoff Henry , Rohwedder William K.
Published: November 2006

To ascertain the effect of a replaceable hydrogen on deuterium incorporation, 2‐pentynol, 2‐hexynol, 3‐hexynol, their tetrahydropyranyl (THP) ethers, and the mono‐ and di‐THP ethers of 3‐hexyne‐1,6‐diol were deuterated catalytically with deuterium gas. The differences in percentd4 (using Wilkinson's catalyst,tris(triphenylphosphine)‐chlororhodium) or percentd2 (using Lindlar's catalyst, Pd on CaCO3 poisoned with a lead salt) measured for the alcohols and their THP ethers were, in general, less than 4% with either catalyst. Noticeable exceptions occurred during the deuteration over Wilkinson's catalyst of 2‐pentynol and 2‐hexynol; extensive scatter resulted in a substantial decrease in percentd4. This scatter was not observed with the corresponding THP ethers.
Effect of dietary fish oil on the rate of very low density lipoprotein triacylglycerol formation and on the metabolism of chylomicrons
Authors: Lottenberg Ana Maria P. , Oliveira Helena C. F. , Nakandakare Edna R. , Quintão Eder C. R.
Published: November 2006

The mechanism by which ω3 fatty acids lower plasma triacylglycerol levels was investigated. Rats were fed fish oil, olive oil (10% fat by weight) or a nonpurified diet 4% fat by weight) for 15 days. Lipoprotein lipase was inhibited by intra‐arterial administration of Triton WR 1339 to estimate hepatic triacylglycerol output. Rats fed the olive oil diet showed a higher rate of triacylglycerol formation than rats fed the ω3 fatty acid diet or the low‐fat diet. All three groups showed identical rates of removal from plasma of intraarterially administered artificial chylomicrons that had simultaneously been labeled with cholesteryl [1‐14C]oleate and [9,10(n)‐3H]triolein. Liver radioactivity and total fat content were lowest in rats fed the fish oil diet, indicating that ω3 fatty acids were preferentially metabolized in liver. Chylomicrons obtained from donor rats fed either fish oil containg [14C]cholesterol or olive oil containing [3H]cholesterol were removed at similar rates when infused together intraarterially into recipient animals. A slower formation of plasma very low density lipoprotein triacylglycerols in rats fed fish oil is probably due to a faster rate of oxidation of the fatty acid chains in the liver resulting in decreased plasma triacylglycerol concentrations.
Effect of dietary fats on some membrane‐bound enzyme activities, membrane lipid composition and fatty acid profiles of rat heart sarcolemma
Authors: Vajreswari A. , Narayanareddy K.
Published: November 2006

The effect of various dietary fats on membrane lipid composition, fatty acid profiles and membrane‐bound enzyme activities of rat cardiac sarcolemma was assessed. Four groups of male weanling Charles Foster Young rats were fed diets containing 20% of groundnut, coconut, safflower or mustard oil for 16 weeks. Cardiac sarcolemma was prepared from each group and the activities of Na+,K+‐ATPase, 5′‐nucleotidase, Ca2+‐ATPase and acetylcholinesterase were examined. ATPase activities were similar in all groups except the one fed coconut oil, which had the highest activities. Acetylcholinesterase activity was also similar in all the groups, however, it was significantly higher in the group fed mustard oil. No significant changes were observed among the groups in 5′‐nucleotidase activity, in the cholesterol‐to‐phospholipid molar ratio and in sialic acid content. The coconut, safflower and mustard oil diets significantly increased cholesterol and phospholipid contents and the lipid‐to‐protein ratio of cardiac sarcolemma as compared to feeding the groundnut oil diet. The fatty acid composition of membrane lipids was quite different among the various groups, reflecting the type of dietary fat given. The total unsaturated‐to‐saturated fatty acid ratio was not different among the various groups; however, the levels of some major fatty acids such as palmitic (16∶0), oleic (18∶1) and linoleic (18∶2) acids were significantly different. Cardiac sarcolemma of the group fed safflower oil had the highest polyunsaturated fatty acid content. The results suggest that dietary fats induce changes not only in the fatty acid composition of the component lipids but also in the activities of sarcolemmal enzymes involved in the regulation of cardiac function.
Lipid composition and mitochondrial respiration in warm‐ and cold‐adapted sea bass
Authors: Trigari Gianni , Pirini Maurizio , Ventrella Vittoria , Pagliarani Alessandra , Trombetti Fabiana , Borgatti Anna Rosa
Published: November 2006

The response to cold of liver and heart membrane lipid composition and mitochondrial respiration in reared sea bass (Dicentrarchus labrax L.) was investigated. Fish acclimation was followed during the natural seasonal cycle from August to March. The data on the fatty acid composition of liver and heart polar lipids and on total lipids of liver mitochondria and microsomes did not indicate any increase in unsaturation in response to cold. The enzyme complexes of the liver and heart mitochondrial respiratory chain showed a repeated negative compensation for cold acclimation. The constancy of the break in the Arrhenius plot of liver cytochrome oxidase (EC 1.9.3.1) was consistent with the lack of homeoviscous adaptation of membrane lipids. A thermoadaptive strategy based on the reduction of sea bass metabolic activity is suggested.
Improved resolution of31P nuclear magnetic resonance spectra of phospholipids from brain
Authors: Capuani G. , Aureli T. , Miccheli A. , Di Cocco M. E. , Ramacci M. T. , Delfini M.
Published: November 2006

A method is described wherein the resolution of31P nuclear magnetic resonance spectra of the lipophilic fraction from a Bligh‐Dyer extract of rat brain can be enhanced. The lipids are dispersed as micelles in aqueous solution with sodium deoxycholate, and spectral resolution is further optimized by adjusting the pH and by removing ions from the solution. The application of the method to the study of aging in rat brain serves as an example.
One‐step synthesis of radioactive acyl‐CoA and acylcarnitines using rat liver mitochondrial outer membrane as enzyme source
Authors: Jalaluddin Bhuiyan A. K. M. , Pande S. V.
Published: November 2006

Rat liver mitochondrial outer membrane enriched preparations have proven to be a convenient enzyme source for synthesizing coenzyme A (CoA) and carnitine esters of radioactive fatty acids. These membranes are simple to isolate and they retain acyl‐CoA ligase and carnitine palmitoyltransferase activities well upon storage. Enzyme purification is not required. A novel aspect of the present procedure is that the same enzymatic incubation step allows both the acyl‐CoA and the acylcarnitine esters to be obtained simulataneously when carnitine is present, but produces acyl‐CoA ester only when carnitine is not included. Under the conditions described, the conversion of [1‐14C]octanoic acid to the respective esters was about 95%; the corresponding figure for [1‐14C]palmitic acids was over 70%. The procedure seems suitable for synthesizing the labeled CoA and carnitine esters from a variety of radioactive fatty acids.
Adenosine triphosphate (ATP) and other nucleotides stimulate the hydrolysis of phosphatidylethanolamine in intact fibroblasts
Authors: Kiss Zoltan , Crilly Karan S.
Published: November 2006

Addition of adenosine triphosphate (ATP) to [14C]ethanolamine‐prelabeled NIH 3T3 fibroblasts resulted in rapid formation of [14C]ethanolamine from the prelabeled cellular phosphatidylethanolamine (PtdEtn) pool. After 2‐min exposure, 10 μM ATP had near maximal effects on PtdEtn hydrolysis. Several other nucleotides, including UTP, ITP, and the stable ATP analog adenosine 5′‐O‐(3‐thiotriphosphate) (ATPγS), also had stimulatory effects on PtdEtn hydrolysis with a potency comparable to that observed with ATP. The same nucleotides which acted on PtdEtn hydrolysis also had similar stimulatory effects on the hydrolysis of phosphatidylcholine (PtdCho) in [14C]choline‐labeled cells. In isolated membranes, Mg2+ greatly enhanced the stimulatory effects of ATP and ATPγS, but not of other nucleotides, on the hydrolysis of PtdEtn and PtdCho. Results indicate that in isolated membranes, both ATP and ATPγS stimulate phospholipid hydrolysis by two different mechanisms, but in intact cells only one of these mechanisms appears to be responsive to externally added nucleotides.
Hypothyroidism and thyroxin substitution affect the n−3 fatty acid composition of rat liver mitochondria
Authors: Raederstorff D. , Meier C. A. , Moser U. , Walter P.
Published: November 2006

The effects of hypothyroidism and of daily treatment for up to 21 days with thyroxin (T4, 0.5 μg/100 g body weight) on the fatty acid composition of total lipid, phosphatidylethanolamine, and phosphatidylcholine of rat liver mitochondria were studied. The fatty acid compositions of hypothyroid and euthyroid (control) rats of similar age were compared. The n−6 and n−3 polyunsaturated fatty acids (PUFA) were affected differently by the hypothyroid state. The levels of linoleic (18∶2n−6), γ‐linolenic (18∶3n−6) and dihomo‐γ‐linolenic acids (20∶3n−6) were higher in hypothyroid rats than in controls, while the level of arachidonic acid (20∶4n−6) was lower, which suggests an impairment of the elongase and desaturase activities. The n−3 polyunsaturated fatty acids, eicosapentaenoic (EPA, 20∶5n−3) and docosapentaenoic (22∶5n−3) acids, were higher in hypothyroid rats, whereas the linolenic acid (18∶3n−3) content remained constant. The level of docosahexaenoic acid (DHA, 22∶6n−3) was dramatically decreased in hypothyroid rats, while the levels of C22n−6 fatty acids were unchanged. The differences were probably due to the competition between n−3 and n−6 PUFA for desaturases, elongases and acyltransferases. When hypothyroid rats were treated with thyroxin, the changes induced by hypothyroidism in the proportions of n−6 fatty acids were rapidly reversed, while the changes in the n−3 fatty acids were only partially reversed. After 21 days of thyroxin treatments, the DHA content was only half as high in hypothyroid rats than in euthyroid rats. These results suggest that the conversion of 18∶2n−6 to 20∶4n−6 is suppressed in the hypothyroid state which favors the transformation of 18∶3n−3 to 20∶5n−3. The marked decrease in DHA content indicates an impairment of the enzymes involved in the DHA metabolism, possibly the n−3 Δ4 desaturase or the acyltransferases. The increased levels of EPA and 22∶5n−3 is consistent with the inhibition of the n−3 pathway at the Δ4 desaturase step. Observed modifications in the fatty acid composition may significantly alter eicosanoid synthesis and membrane functions in hypothyroidism.
Incorporation of n−3 fatty acids into WB‐F344 cell phospholipids inhibits gap junctional intercellular communication
Authors: Hasler Clare M. , Trosko James E. , Bennink Maurice R.
Published: November 2006

In this investigation, we demonstrate that rat liver epithelial (WB‐F344) cells grown in medium supplemented with n−3 fatty acids (FA) results in the inhibition of gap junctional intercellular communication (GJIC). Cells incubated for 48 hr in medium containing 50 μM α‐linolenate (18∶3n−3) resulted in a 60% inhibition of GJIC, compared to control cells, while treatment with γ‐linolenate (18∶3n−6) had no effect. Supplementation with octadecatetraenoate (18∶4n−3), eicosapentaenoate (20∶5n−3), and docosahexaenoate (22∶6n−3), inhibited GJIC by 42%, 28%, and 18%, respectively. Incubation with each of the n−3 FA markedly increased the total n−3 FA content of cellular phospholipids (PL). Growing cells in medium containing 50 μM arachidonate (20∶4n−6) plus 50 μM 18∶3n−3 partially attenuated the inhibition of GJIC induced by 18∶3n−3. The mechanism by which n−3 FA inhibit GJIC remains to be determined.
Rapid three‐step purification of a hepatic neutral cholesteryl ester hydrolase which is not the pancreatic enzyme
Authors: Ghosh Shobha , Grogan W. McLean
Published: November 2006

A rat liver cytosolic cholesteryl ester hydrolase (CEH) was purified 12,600‐fold by ammonium sulfate precipitation, cation exchange chromatography and gel permeation high‐performance liquid chromatography, with an overall yield of 20%. Its properties are compared to those of pancreatic CEH, with which it has sometimes been identified. Liver CEH exhibited a single silver stained band following SDS‐polyacrylamide gel electrophoresis (Mr=66 kDa), was activated by 0.5–10 mM taurocholate but was strongly inhibited by higher levels of taurocholate, which activate pancreatic CEH. Whereas bile salts are known to induce formation of a hexamer of pancreatic CEH, in the current study, 0.5 mM taurocholate dissociated a multimeric form of liver CEH to monomer. Liver CEH did not coelute with pancreatic CEH from cation exchange and chromatofocusing columns, exhibited no immunoreactivity with anti‐rat pancreatic CEH IgG in Western blots, was not inhibited by anti‐rat pancreatic CEH IgG and had a different amino acid composition from pancreatic CEH. In contrast to liver CEH, which is known to be activated by protein kinases A and C, pancreatic CEH was unaffected by cofactors for protein kinase A and was inhibited by cofactors for protein kinase C.
Effect of chylomicron remnants on cholesterol metabolism in cultured rabbit hepatocytes: Very low density lipoprotein and bile acid production
Authors: Kosykh Vladimir A. , Novikov Dmitri K. , Trakht Iliya N. , Podrez Eugeni A. , Victorov Alexander V. , Repin Vadim S. , Smirnov Viadimir N.
Published: November 2006

The interrelationship between very low density lipoprotein (VLDL) secretion and bile acid production was studied in primary culture of rabbit hepatocytes. Chylomicron remnants (CR) were added to the cultures to study their effect on VLDL secretion and bile acid production. After 24 hr preincubation of cells with CR (10–50 μg protein/mL), intercellular neutral lipid content was increased 1.5–4‐fold in a dose‐dependent manner. Neutral lipid accumulation was accompanied by a 70–90% reduction of [14C]acetate incorporation into cholesterol, while no stimulation of [14C]oleate incorporation into cholesteryl esters was observed. Incubation of cells with CR increased secretion of free cholesterol, triacylglycerol and apoproteins B and E in VLDL. Stimulation of VLDL cholesterol secretion was accompanied by a reduction of taurocholic acid synthesis. These data demonstrate the existence of an inverse relationship between secretion of VLDL cholesterol and bile acid production under conditions of effective uptake of triacylglycerol‐rich CR by hepatocytes.
Similarities in surface lipids of chylomicrons from glyceryl and alkyl ester feeding: Major components
Authors: Yang Lu‐Ying , Kuksis Arnis , Myher John J.
Published: November 2006

This study tests the hypothesis that the rat chylomicrons are assembled and released into lymph similarly regardless of the site (rough or smooth endoplasmic reticulum) or pathway (phosphatidic acid or monoacylglycerol) of triacylglycerol biosynthesis. For this purpose we determined the lipid class, fatty acid and molecular species composition of the choline, ethanolamine, inositol and serine phospholipids of lymph chylomicrons during absorption of menhaden, mustard‐seed and corn oil (monoacylglycerol pathway) or the corresponding fatty acid methyl or ethyl esters (phosphatidic acid pathway). The dietary fatty acids were found to be incorporated to various extents into different phospholipid classes, the proportions of which were not affected by the nature of the dietary fat. The chylomicron phospholipids contained 80–82% choline, 8% ethanolamine and 2.5% inositol glycerophospholipids, and much smaller amounts of serine and other minor phospholipids. Administration of a meal of each dietary fat resulted in a retention of approximately 50% endogenous fatty acids in the major glycerophospholipids of the chylomicrons. A minimum of 50% of the molecular species of the choline and ethanolamine glycerophospholipids contained at least one exogenous fatty acid. No significant discrepancies were found in the fatty acid and molecular species composition of the glycerophospholipids between chylomicrons from the oil and corresponding ester feeding. It is concluded that the chylomicrons arising from the monoacylglycerol (oil feeding) and the phosphatidic acid (ester feeding) pathways of triacylglycerol biosynthesis become enveloped in surfactant monolayers containing qualitatively and quantitatively identical classes and molecular species of phospholipids.
Compositional changes and apoprotein A‐I metabolism of plasma high density lipoprotein in estrogenized chicks
Authors: Cho B. H. Simon , Park Jeong R.
Published: November 2006

The effect of estrogen on compositional changes, apolipoprotein (apo) A‐I metabolism and the morphology of plasma high density lipoprotein (HDL) were investigated in chicks. The administration of 17β‐estradiol (25 mg/kg body weight) to growing male chicks (8‐week‐old) markedly reduced the concentrations of plasma HDL components, except for triglyceride (TG). At the same time, levels of TG, total cholesterol (TC) and phospholipid (PL) in plasma were greatly elevated. The respective values for TG, TC, PL and protein in HDL were 13.9, 89.3, 154.1 and 231.7 (mg/dL) in the control, and 39.0, 35.1, 113.8 and 160.0 (mg/dL) in chicks upon estrogen treatment for one day.In vivo kinetic studies showed that the fractional catabolic rate of HDL apo A‐I was significantly higher (p<0.05) in estrogen‐treated chicks than in control birds, indicating an increased efficiency of HDL removal in the former. The production rate of HDL apo A‐I also was significantly lower (p<0.05) in estrogen‐treated chicks. Sodium dodecyl sulfate‐acrylamide gel electrophoresis followed by laser scanning densitometry of HDL apolipoproteins in estrogen‐treated chicks revealed a reduction of apo A‐I and the occurrence of new apolipoproteins which had been absent in HDL of untreated birds. The HDL particles showed that the mean particle size of HDL became larger upon estrogen treatment. Particles with diameters between 70 and 123 Å were predominant in HDL of control chicks, while particles with diameters between 97 and 143 Å were most abundant in HDL of estrogen‐treated chicks.
In vivo determination of triglyceride secretion using radioactive glycerol in rats fed different dietary saturated fats
Authors: Lai Hui‐Chuan , Lasekan John B. , Yang Huan , Clayton Murray K. , Ney Denise M.
Published: November 2006

Our objective was to determine the relative rates ofin vivo triglyceride (TG) secretion and the composition of very low density lipoproteins (VLDL) in rats fed different dietary saturated fats. Male Sprague‐Dawley rats (150–200 g) were fed diets containing 16% corn oil, or 14% butterfat, 14% beef tallow, 14% olive oil, or 14% coconut oil plus 2% corn oil for 5 wk. Changes in plasma TG specific radioactivity were determined in individual, unanesthetized fasted rats after injection of 100 μCi [2‐3H]glycerol. Nonlinear regression analysis using a 2‐compartment model was used to determine the fractional rate constant for TG turnover in plasma. The plasma TG pool was 33–40% larger with beef tallow than with corn, olive or coconut oil feeding (p<0.05), and 20% larger with beef tallow than with butterfat feeding. The rate of TG secretion into plasma (mg/min/100 g body weight) was 60% higher in animals fed beef tallow than corn or coconut oil (p<0.05) and 26–33% higher in animals fed beef tallow than olive oil or butterfat. Differences in VLDL composition (% wt) were also noted. Our data suggest that greater TG secretion is the primary factor contributing to the larger TG pool with ingestion of beef tallow relative to butterfat, corn or coconut oil. These results suggest that different dietary saturated fats have unique effects on TG metabolism in rats.
Further oxidation products of 2,2,5,7,8‐pentamethyl‐6‐chromanol
Authors: Suarna Cacang , Baca Manuel , Craig Donald C. , Scudder Marcia , Southwell‐Keely Peter T.
Published: November 2006

In order to undertake a quantitative study by high‐performance liquid chromatography of the rate of oxidation of 2,2,5,7,8‐pentamethyl‐6‐chromanol (1), the model compound of α‐tocopherol, a number of potential products were required as standards. Among these compounds were 2,2,7,8‐tetramethylchroman‐5,6‐dione (10) and 2,2,7‐trimethyl‐6‐hydroxychroman‐5,8‐dione (17), the model compounds of tocored and tocopurple, respectively. Attempts to synthesize 10 and 17 led to the isolation of 8‐hydroxymethyl‐2,2,7‐trimethylchroman‐5,6‐dione (14) and 1,2‐bis(2,2,7‐trimethylchroman‐5,6‐dione‐8‐)ethane (19) a dimer of 10. Purification by thin‐layer chromatography of the spirodimer (20) of 1 resulted in an acid‐catalyzed decomposition to 1‐(2,2,7,8‐tetramethyl‐6‐chromanol‐5‐)2‐[2‐(3‐methyl‐3‐hydroxybutyl)‐5,6‐dimethyl‐1,4‐benzoquinone‐3‐]ethane (23), a new chromanol‐quinone dimer.
Lipid hydroperoxide measurement by oxidation of Fe2+ in the presence of xylenol orange. Comparison with the TBA assay and an iodometric method
Authors: Jiang Zhen‐Yue , Woollard Alison C. S. , Wolff Simon P.
Published: November 2006

Study of the role of hydroperoxides and lipid peroxidation in disease requires simple and sensitive methods for direct hydroperoxide measurement. We report on a technique for measuring hydroperoxide which relies upon the rapid hydroperoxide‐mediated oxidation of Fe2+ under acidic conditions. Fe3+ forms a chromophore with xylenol orange which absorbs strongly at 560 nm, yielding an apparent E560 (for H2O2, butyl hydroperoxide and cumene hydroperoxide) of 4.3×104 M−1 cm−1. The assay was validated in a study of liposomal lipid peroxidation and shown to give results comparable with those obtained by an iodometric method or by measuring conjugated dienes. The assay involving thiobarbituric acid, by comparison, underestimates lipid peroxidation and does not measure hydroperoxideper se.
Effects of perfluorodecanoic acid onde novo fatty acid and cholesterol synthesis in the rat
Authors: Davis John W. , Vanden Heuvel John P. , Peterson Richard E.
Published: November 2006

Perfluorodecanoic acid (PFDA) is a peroxisome proliferator that causes a dose‐dependent (20–80 mg/kg) increase in hepatic triacylglycerol and cholesteryl ester levels in the rat. We hypothesized that PFDA may cause an increase in thede novo synthesis of fatty acids and cholesterol in this species, which would explain observed effects. The incorporation of3H2O into tissue lipids was examined 7 days after rats received vehicle or 20 or 80 mg/kg of PFDA. PFDA treatment decreased the rate of synthesis of cholesterol and fatty acids in the liver and in epididymal fat pad. At a PFDA dose (20 mg/kg) that decreasedde novo synthesis of fatty acids and cholesterol, there was no effect on the concentration of fatty acids and cholesterol in the liver, epididymal fat pads, and plasma. We conclude that PFDA induced fatty liver is due to either a decrease in the oxidation of fatty acids in the liver, or an impairment of triacylglycerol catabolism and/or export from the liver, and is not the result of an increase inde novo synthesis of fatty acids and cholesterol.