bluuebunny/crossref_metadata_2025 huggingface dataset:
The occurrence of long chain α,ω‐diols in the lipids of steer and human meibomian glands
Authors: Nicolaides N. , Santos Evelyn C. , Papadakis Konstantine , Ruth Edward C. , Müller Luciano
Published: November 2006

A group of long chain α,ω‐diols (C29 to C34) has been identified in the lipids of steer and human meibomian gland excreta (meibum). These new lipids were isolated from the steer meibum unsaponifiables. Proof of structure was provided by 1) the column chromatographic behavior and TLC of the diols and their diacetates; 2) GLC on glass capillary columns; 3) fragmentation patterns in GC‐MS; 4) NMR data, and 5) ozonolysis studies of the unsaturates. Chain types for the steer sample were 51% straight monoenes, 8.5% straight saturates, 39% iso and anteiso saturates and 1.5% iso and anteiso unsaturates. GC for the human sample gave straight monoenes 83%, straight saturates 8%, and iso plus anteiso saturates 9%. Close correspondence of the α,ω‐diol chain lengths and types with meibum ω‐hydroxy fatty acids suggests a biochemical precursor relationship.
Metabolism of sterols of varying ring unsaturation and methylation byCaenorhabditis elegans
Authors: Lozano Ruben , Salt Thomas A. , Chitwood David J. , Lusby William R. , Thompson Malcolm J.
Published: November 2006

The metabolism of three dietary 4,4‐desmethylsterols and two 4α‐methylsterols was investigated in the free‐living nematodeCaenorhabditis elegans. Dietary cholestanol was converted mostly to lathosterol. Dietary lathosterol, 7‐dehydrocholesterol, 4α‐methylcholest‐7‐enol and 4α‐methylcholest‐8(14)‐enol each remained largely unchanged. An absolute requirement for a substantial quantity of 7‐dehydrocholesterol inC. elegans did not exist.C. elegans was unable to remove a 4α‐methyl group or introduce a double bond at C‐5 and also demonstrated the lack of a Δ7‐reductase. Its nutritional sterol requirement was satisfied by cholestanol, lathosterol or 7‐dehydrocholesterol; growth was comparable to that obtained previously in media containing Δ5‐sterols. However, the two 4α‐methylsterols appeared to be unsatisfactory sterol nutrients. The possible physiological importance of 4α‐methylsterols is discussed briefly.
Measurement of free and bound malondialdehyde in vitamin E‐deficient and‐supplemented rat liver tissues
Authors: Lee Hye‐Sung , Saari Csallany A.
Published: November 2006

The quantity of free malondialdehyde (MDA) in liver tissues of rats fed vitamin E‐deficient or‐supplemented diets for 43 wk was measured by a newly developed high performance liquid chromatographic (HPLC) method. Bound MDA was quantified by the same HPLC method after alkaline hydrolysis of tissue homogenates. Tissues from vitamin E‐deficient animals showed levels of free MDA about 15 times higher but levels of bound MDA less than 2 times higher than the vitamin E‐supplemented animals. Free MDA is the major form in vitamin E‐deficient tissues, but bound MDA is predominant in vitamin E‐supplemented tissues. Conventional thiobarbituric acid (TBA) test results revealed that the content of TBA‐reactive substances expressed in MDA equivalents was much higher than the actual free MDA levels in all groups. Results indicate that free MDA level measured by HPLC is a more sensitive index than the TBA value for lipid peroxidation. Some other TBA‐reactive substances seem to exist in liver tissue regardless of the dietary treatment.
Cholesteryl esterase activities in ventricles, isolated heart cells and aorta of the rat
Authors: Stam Hans , Broekhoven‐Schokker Sietske , Schoonderwoerd Kees , Hülsmann Willem C.
Published: November 2006

Cholesteryl esterase activities were determined in homogenates of rat heart (ventricles), isolated, calcium‐tolerant, cardiac myocytes and aortic tissue and were compared with acid and neutral triglyceride lipase activities in these fractions.

Using cholesteryl oleate/phosphatidylcholine/taurocholate emulsions and digitonin pretreatment of the enzyme fractions, acid and neutral cholesteryl esterase activities were measured in all tissue preparations. In contrast to the acid and neutral triglyceridase and acid cholesteryl esterase activity, the neutral cholesteryl esterase activity was subject to substrate inhibition. Upon isolation of cardiac myocytes, and in contrast with the recovery of neutral triglyceride lipase activity, only a small portion of the neutral cholesteryl esterase (6%) was recovered, suggesting that nonmyocyte neutral cholesteryl esterase activity markedly contributes to the relatively high activity detectable in whole ventricular homogenates. The recovery of large amounts of neutral cholesteryl esterase activity in the supernatant of collagenase‐digested heart tissue, obtained during the isolation of myocytes, which is also markedly enriched in activities of two endothelial marker enzymes (5′‐nucleotidase and angiotesine‐converting enzyme) may indicate the predominant contribution of neutral cholesteryl esterase activity from coronary endothelial cells to this activity detectable in ventricular homogenates. Relative to the activity in ventricular and myocyte homogenates, aorta homogenates possessed the highest specific neutral cholesteryl esterase activity. We propose that in addition to coronary endothelium, smooth muscle cells also contribute to the neutral cholesteryl esterase activity in ventricular homogenates. Pretreatment of rats with carrageenan an agent toxic to macrophages, lymphocytes and fibroblasts, induced a significant drop in myocardial neutral cholesteryl esterase and triglyceride lipase activity, suggesting that interstitially trapped macrophages may also contribute to lipolytic activities present in whole ventricular homogenates. Our data indicate that caution has to be taken upon extrapolation of experimental findings in heart homogenates to myocardial muscle cells.
Resolution of radiolabeled molecular species of phospholipid in human platelets: Effect of thrombin
Authors: Purdon A. David , Patelunas D. , Smith J. Bryan
Published: November 2006

Resolution of individual molecular species of human platelet 1,2‐diradyl‐sn‐glycero‐3‐phosphocholines and 1,2‐diradyl‐sn‐glycero‐3‐phosphoethanolamines by reverse phase high pressure liquid chromatography (HPLC) allowed a thorough analysis of those phospholipids labeled with [3H]arachidonic acid. Approximately 54% and 16% of the total incorporated radiolabel was found in choline glycerophospholipids and ethanolamine glycerophospholipids, respectively, with ca. 90% of this being found in the 1,2‐diacyl molecular species. Eighty percent of [3H]‐arachidonic acid incorporated into 1‐acyl‐2‐arachidonoyl‐sn‐glycero‐3‐phosphocholine in resting platelets was equally distributed between 1‐palmitoyl‐2‐arachidonoyl and 2‐stearoyl‐2‐arachidonoyl‐sn‐glycero‐3‐phosphocholine, while 70% of the radiolabel in 1‐acyl‐2‐arachidonoyl‐sn‐glycero‐3‐phosphoethanolamine was found in 1‐stearoyl‐2‐arachidonoyl‐sn‐glycero‐3‐phosphoethanolamine. Thrombin stimulation (5 U/ml for 5 min) resulted in deacylation of all 1‐acyl‐2‐[3H]arachidonoyl molecular species of 1‐acyl‐2‐arachidonoyl‐sn‐glycero‐3‐phosphocholine and 1‐acyl‐2‐arachidonoyl‐sn‐glycero‐3‐ethanolamine. There was also a slight increase in 1‐O‐alkyl‐2‐[3H]arachidonoyl‐sn‐glycero‐3‐phosphocholine and a significant increase in 1‐O‐alk‐1′‐enyl‐2‐[3H]arachidonoyl‐sn‐glycero‐3‐phosphoethanolamine molecular species of over 300%. Thus, HPLC methodology indicates that arachidonoyl‐containing molecular species of phosphatidylcholine and phosphatidylethanolamine are the major source of arachidonic acid in thrombin‐stimulated human platelets, while certain ether phospholipid molecular species become enriched in arachidonate.
Electrochemical detection of phospholipid hydroperoxides in reverse‐phase high performance liquid chromatography
Authors: Yamada K. , Terao J. , Matsushita S.
Published: November 2006

Hydroperoxy derivatives of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) can be separated from their respective phospholipids by reverse‐phase high performance liquid chromatography (HPLC). However, ultraviolet absorption due to conjugated diene cannot detect the hydroperoxy group. In this work, an electrochemical (EC) detector was first applied to the analysis of hydroperoxy phospholipids. Both the PC and PE hydroperoxides from rat liver were reduced quantitatively by the glassy carbon electrode at −300 mV vs Ag/AgCl. Since neither the hydroxy derivatives nor unoxidized phospholipids showed any response, it would seem this technique can be used to distinguish phospholipid hydroperoxides from their hydroxy derivatives. Thus, the reverse phase HPLC‐EC detection method is proposed for the specific analysis of hydroperoxy phospholipids in biological tissues.
The major gangliosides of the bovine pineal body
Authors: Whalen Margaret M. , Wild Gaynor C.
Published: November 2006

Acetone powders of fresh‐frozen pineals were extracted with chloroform/methanol mixtures. By column chromatography on silicic acid, mild alkaline methanolysis, ion‐exchange high performance liquid chromatography and a final thin layer chromatography on silicic acid, the major glycosphingolipids were purified from the extracts of a total of 300 bovine pineal bodies. Chromatographically purified fractions were characterized by gas chromatographic analysis. The most prominent glycosphingolipid appeared to be cerebroside. In addition, five different gangliosides were found in detectable levels. The two major gangliosides have the chromatographic and component characteristics of GD3 and GM3, with disialoganglioside predominating. Gangliosides indistinguishable from purchased standards of GM1 and GD1a were third and fourth, respectively, in amount. The fatty acid profiles of the two lactosyl gangliosides are similar and significantly different from those of the two gangliotetraose gangliosides. The fifth most prominent ganglioside, present at a level of 1.09% of total recovered ganglioside sialic acid, appears to be a novel trisialoganglioside, called GTx. This new molecule has a component ratio of gal:glc:sialic acid:amino sugar of approximately 1∶2∶3∶1. Similarities between bovine pineal and rod outer segments are discussed.
Onset and persistence of changes in intestinal transport following dietary fat manipulation
Authors: Thomson A. B. R. , Keelan M. , Clandinin M. T.
Published: November 2006

In this study we determined the time‐course for the onset and the loss of the effect of short‐term feeding rats isocaloric semisynthetic diets containing a high content of saturated (HS) or polyunsaturated (HP) fatty acids on the jejunal and ileal uptake of medium‐ and long chain fatty acids, cholesterol and glucose. Animals were fed HP or HS for 3, 7 or 14 days; then the diet was switched to standard Purina® rat chow for a further 3, 7 or 14 days. The uptake of medium chain fatty acids was unchanged. The differences between HP and HS in glucose uptake occurred within 3 days, but persisted for 14 days, whereas there were qualitative as well as quantitative changes in the pattern of lipid uptake: differences in uptake of stearic, oleic, linoleic and linolenic acids and cholesterol occurred after 7 days of feeding HP or HS. Jejunal uptake of linoleic acid was greater in HP than HS on day 7, but HS was greater than HP on day 14. The effect of diet on lipid uptake was similar in the jejunum and ileum. The altered uptake of stearic and oleic acids persisted after the rats were switched back to chow, whereas the uptake of the other nutrients became similar. Thus, (i) changes in dietary content of saturated and polyunsaturated fatty acids have early effects on intestinal transport function; (ii) some of these changes persist even when animals are returned to feeding on chow; and (iii) glucose transport is rapidly altered by dietary changes, whereas lipid uptake changes only after 7 days. We conclude that the transport function of the intestine is responsive to changes in dietary fatty acids.
Intestinal cholesterol and oleic acid uptake from solutions supersaturated with lipids
Authors: Reynier M. O. , Crotte C. , Montet J. C. , Sauve P. , Gerolami A.
Published: November 2006

To test the role of nonmicellar phases in lipid absorption, intestinal uptake of fatty acids and cholesterol has been studied in vitro from supersaturated and micellar solutions. The micellar solubility limit at equilibrium was established for cholesterol and oleate/monoolein (2∶1) at pH 6.7 with 10 mM taurocholate. Uptake by rat intestinal everted sacs was measured during incubation of 5 min. Cholesterol uptake increased linearly with the cholesterol content of micellar or supersaturated solutions up to a supersaturation of 150%. Oleate uptake, by contrast, remained essentially the same from either saturated or supersaturated (130–280%) mixtures. The difference between cholesterol and oleate uptake rates is explained by their distinct effects on micellar size, which is unchanged by cholesterol supersaturation but is increased by oleate. Solutions largely supersaturated (280%) with oleatemonoolein are polydisperse and contain viscous isotropic and paracrystalline phases similar to those observed during lipid absorption. These results suggest that, in the presence of such solutions, uptake occurs from both the micellar saturated and nonmicellar supersaturated phases.
Intestinal absorption of ester and ether glycerophospholipids in guinea pig. Role of a phospholipase A2from brush border membrane
Authors: Diagne A. , Mitjavila S. , Fauvel J. , Chap H. , Douste‐Blazy L.
Published: November 2006

In vivo intestinal perfusion was used to follow the absorption of three different choline glycerophospholipids (CGP) in guinea pig. These included 1‐[3H]palmitoyl‐2‐acyl‐sn‐glycero‐3‐phosphocholine (diacyl‐GPC), 1‐[3H]‐O‐hexadecyl‐2‐acyl‐sn‐glycero‐3‐phosphocholine (alkylacyl‐GPC) and 1,2‐di‐O‐hexadecyl‐sn‐glycero‐3‐phospho‐[3H]‐choline (dialkyl‐GPC). About 80% of diacyl‐GPC was absorbed within 4 hr, compared to 60% of alkylacyl‐GPC and 30% of dialkyl‐GPC. The radioactivity disappearing from the perfusion fluid was recovered in intestinal lipids, mostly triacylglycerol, free fatty acid and CGP from diacyl‐GPC, CGP from alkylacyl‐GPC and dialkyl‐GPC. These results indicated that the nonhydrolyzable substrate dialkyl‐GPC was much less absorbed, whereas diacyl‐GPC, which released over 80% of [3H]palmitic acid in the perfusion fluid, displayed the highest absorption rate. The intermediate picture observed for alkylacyl‐GPC suggested the possible involvement of a phospholipase A2, which was detected in the entire intestinal tract. This enzyme was further found to concentrate in villus cells, where it is localized in the brush border membrane, as shown using two different subcellular fractionation procedures. These data suggest a possible role of this new enzyme in the digestion of alimentary phospholipids.
Lipids fromPlasmodium vinckei‐infected erythrocytes and their susceptibility to oxidative damage
Authors: Stocker Roland , Cowden William B. , Tellam Ross L. , Weidemann Maurice J. , Hunt Nicholas H.
Published: November 2006

The constituent lipids of plasma and red blood cells (RBC) from mice late in infection with the malarial parasitePlasmodium vinckei were analyzed and compared with those obtained from uninfected animals. On a dry weight basis, the total extractable lipids of RBC increased three‐fold during infection, while those of the plasma did not change significantly. In general, changes in individual plasma lipid constituents paralleled those found in RBC of infected mice but were of smaller magnitude. While the increase in the total lipids of parasitized RBC was largely attributable to an increase of more than fourfold in total phospholipids, a significant increase in neutral lipids was also observed. Phosphatidylcholine and phosphatidylethanolamine were the major phospholipids present within RBC, and their total and relative concentrations increased as a result of the infection. A parallel increase occurred in the ratio of unsaturated to saturated fatty acids in the parasitized RBC phospholipids. Infection was also associated with decreases in the relative amount of cholesterol present in RBC and in the ratio of cholesterol to phospholipid. Consistent with this, the fluorescence polarization of 1[4‐(trimethylamino)phenyl]‐6‐phenylhexa‐1,3,5‐triene within parasitized RBC plasma membranes was decreased in comparison with its value in noninfected RBC, indicating that malarial infection decreases the “order” of membrane lipids. These modifications, in conjunction with the increased levels of vitamin E and malonyldialdehyde reported elsewhere, are important determinants of the susceptibility of the different membrane compartments within infected RBC to peroxidative damage.
Improved enzymatic hydrolysis of conjugated bile acids
Authors: Highsmith W. Edward , Hyde Paul M.
Published: November 2006

The hydrolysis of conjugated bile acids by cholylglycine hydrolase (EC 3.5.1.24) using the standard procedure for a commercial enzyme preparation was found to be incomplete, as judged by the use of 24‐14C‐taurocholic acid as a tracer. A method is proposed that incorporates the nonionic detergent Triton X‐100 into the reaction mixture to achieve almost complete hydrolysis. It is proposed that the observed enhancement of enzyme activity is due to the formation of micelles by the detergent.
Serum lipid abnormalities in a chemical/viral mouse model for Reye's syndrome
Authors: Murphy M. G. , Archambault‐Schertzer L. , Ackman R. G. , Crocker J. F. S.
Published: November 2006

Neonatal mice given nontoxic dermal applications of an industrial surfactant, Toximul MP8 (Tox), and subsequently infected with sublethal doses of mouse‐adapted human Influenza B (Lee) virus (FluB) develop many of the biochemical features of Reye's Syndrome (RS). To determine whether these also include abnormal circulating lipid, we examined serum lipid profiles in the mouse model throughout the treatment course using Iatroscan‐TH10. Following 10 days of exposure to surfactant, serum phospholipid and cholesterol levels were significantly reduced relative to control animals. These reductions were transient; however, four days following virus administration, significant differences in serum lipid were again evident. These abnormalities coincided and correlated with increased animal mortality. Animals that received combined Tox + virus treatment had significant decreases in serum total lipids relative to control animals, a reflection of a reduction in all lipid classes, including phospholipid, cholesterol, neutral glycerides (triglycerides plus diglycerides) and free fatty acids. Phospholipid (specifically phosphatidylcholine and lysophosphatidylcholine) and free fatty acid levels in the Tox + virus group were also significantly lower than those in animals that received virus alone. This study has demonstrated that suckling mice given chemical/viral treatment have the serum hypopanlipidemia but not the freefattyacidemia that are characteristic of RS.
Autoxidation of cholesterol in tallows heated under deep frying conditions: Evaluation of oxysterols by GLC and TLC‐FID
Authors: Bascoul J. , Domergue N. , Olle M. , de Paulet A. Crastes
Published: November 2006

The products of cholesterol autoxidation (oxysterols) in heated animal food fat were determined qualitatively and quantitatively to evaluate their toxicity and those of the foods in which they occur. Samples of beef tallow were taken from deep‐fat fryers while they were in use. The oxysterols were identified and assayed by gas liquid chromatography and thin layer chromatography on Chromarods with flame ionization detection (TLC‐FID). The two methods were compared and the TLC‐FID method was found more convenient for a rapid estimation of autoxidation. Of the original cholesterol, 25% was destroyed during cooking and partly transformed into 3β‐5‐6β‐trihydroxy‐5α‐cholestane, 7α‐hydroxy‐, 7β‐hydroxy‐, 7‐oxo‐cholesterol, 7‐oxo‐cholesta‐3‐5‐diene and cholesterol epoxides. Certain other oxysterols were present in smaller quantities.
Mechanism of anesthesia: The potency of four derivatives of octane corresponds to their hydrogen bonding capacity
Authors: Brockerhoff Hans , Brockerhoff Susan , Box Lynda L.
Published: November 2006

The anesthetic potency of four derivatives of n‐octane was measured by tadpole righting reflex and expressed as effective millimolar concentration of drug in membrane, ED50M. Potency diminished (ED50 increased) in this order: 1‐octanol, ED50M=5.5; 1‐(2‐methoxyethoxy)octane, ED50M=28; 1‐methoxyoctane, ED50M=61; and 1‐cholorooctane, ED50M>100. Since the aliphatic chain length was kept constant it is concluded that the differences in anesthetic potency are a consequence of the differences in head group structure. This results is predicted by a theory (Lipids 17, 1001–1003 [1982]) which holds that anesthesia is the result of a drug‐induced restructuring of the hydrogen belts, those strata of the membrane that contain the hydrogen bond receiving and donating CO and OH group of the membrane lipids and the adjoining proteins. The Meyer‐Overton rule for anesthetics should be modified: chemical induce anesthesia at equimolar in‐membrane concentration provided their hydrogen‐bonding parts are identical.
Effect of pyridoxine deficiency on phospholipid methylation in rat liver microsomes
Authors: Loo George , Smith John T.
Published: November 2006

The effect of altered methionine metabolism during pyridoxine deficiency on the activity of phosphatidyl‐ethanolamine methyltransferase (EC 2.1.1.17) and the levels of phosphatidylethanolamine (PE) and phosphatidylcholine (PC) has been evaluated in rat liver microsomes. Animals fed a pyridoxine‐deficient diet for 7 wk displayed a fivefold increase in the hepatic tissue level of S‐adenosylhomocysteine when compared to either control or pair‐fed animal counterparts. When PE methyltransferase was assayed in vitro, a significant increase in specific activity was observed using enzyme preparations from either pair‐fed or pyridoxine‐deficient rats. On the other hand, phospholipid levels did not conform to the measured enzyme activity. The level of PC in microsomes from either pyridoxine‐deficient or pair‐fed animal groups was significantly lower than that determined for the control group of rodents. However, the level of PC was noticeably lower in microsomes from pyridoxine‐deficient animals than that from pair‐fed animals, which received 45% of the feed intake of the control animals. In addition, the level of PE in microsomes from pair‐fed and pyridoxine‐deficient animals was significantly higher than that analyzed from the control animals, further confirming decreased methylation of substrate to product. It is concluded that pyridoxine deficiency may alter the methylation of phospholipid in the endoplasmic reticulum above and beyond that produced by feed restriction alone.
Plasma membrane lipids of bovine adrenal chromaffin cells
Authors: Malviya A. N. , Gabellec M. M. , Rebel G.
Published: November 2006

The lipid composition of plasma membranes isolated from bovine adrenal chromaffin cells has been determined. Choline and ethanolamine phosphatides were predominant; the level of lyso compounds was very low. The amount of cholesterol and the cholesterol/phospholipid molar ratio was low compared to those of the other subcellular fractions of chromaffin cells. A complex pattern of neutral glycolipids was observed in contrast to that of gangliosides.
Diurnal rhythm of HMG CoA reductase activity in canine intestine is independent of luminal contents
Authors: Gebhard Roger L. , Sievert Chester E. , Prigge William F.
Published: November 2006

Activity of the enzyme 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase (EC 1.1.1.34) measured in isolated segments of canine intestinal mucosa showed a distinct diurnal rhythm. Total activity changed over a twofold range with a peak occurring during midday, shortly after feeding. Since the isolated segments had no contact with luminal contents, the rhythm was not directly related to food components or bile salts. Humoral or neural influences must mediate the rhythm. The diurnal rhythm persisted for at least 3–5 mo, but was lost by 10 mo following formation of the isolated segment, possibly because of mucosal involution.
Age‐related changes in the lipid compositions of rat and human tissues
Authors: Kalén Anders , Appelkvist Eeva‐Liisa , Dallner Gustav
Published: November 2006

The levels of cholesterol, ubiquinone, dolichol, dolichyl‐P, and total phospholipids in human lung, heart, spleen, liver, kidney, pancreas, and adrenal from individuals from one‐day‐old to 81 years of age were investigated and compared with the corresponding organs from 2 to 300 day‐old rats. The amount of cholesterol in human tissues did not change significantly during aging, but the level of this lipid in the rat was moderately elevated in the organs of the oldest animals. In human pancreas and adrenal the ubiquinone content was highest at one year of age, whereas in other organs the corresponding peak value was at 20 years of age, and was followed by a continuous decrease upon further aging. A similar pattern was observed in the rats, with the highest concentration of ubiquinone being observed at 30 days of age. Dolichol levels in human tissues increase with aging, but they increase to very different extents. In the lungs this increase is seven‐fold, and in the pancreas it is 150‐fold. The elevation in the dolichol contents of rat tissues ranges from 20 to 30‐fold in our material. In contrast, the levels of the phosphorylated derivative of dolichol increased to a more limited extent, i.e., 2 to 6‐fold in human tissues and even less in the rat. These results demonstrate that the levels of a number of lipids in human and rat organs are modified in a characteristic manner during the life‐span. This is in contrast to phospholipids, which constitute the bulk of the cellular lipid mass.
Molecular species analysis of phosphoglycerides from the ripe roes of cod (Gadus morhua)
Authors: Bell M. V.
Published: November 2006

Molecular species of the 3,5‐dinitrobenzoyl derivatives of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI) were quantitated by UV detection at 254 nm after reversed‐phase HPLC using solvent systems modified from Takamuraet al. (Lipids 21, 356–361, 1986). Three isocratic solvent systems were used and a total of 39 different molecular species detected. Four species, 16∶0/20∶5, 18∶1/20∶5, 16∶0/22∶6 and 18∶1/22∶6 contributed 67.2% and 61.8% of PC and PE respectively but only 23.0% of PI. In PI the most important species was 18∶0/20∶4 at 36.7% but this species only constituted 0.7% in each of PC and PE. Small amounts of dipolyunsaturated species were also found in PC and PE.
The suppression of eicosanoid synthesis by peritoneal macrophages is influenced by the ratio of dietary docosahexaenoic acid to linoleic acid
Authors: Lokesh Belur R. , Black J. Mark , Kinsella John E.
Published: November 2006

The efficacy of docosahexaenoic acid (DHA) in suppressing eicosanoic synthesis by peritoneal macrophagesin vivo was influenced by the relative amount of dietary DHA when linoleic acid (LA) was held constant. Increasing DHA from 0 to 37% of the fatty acids in diets containing 10 weight % fat (of which LA was 40%) caused an eleven‐fold increase in the DHA content of macrophages. Limited retroconversion of DHA to eicosapentaenoic acid was observed. Macrophages in animals consuming DHA synthesized significantly lower amounts of leukotriene E4, prostaglandin E2 and 6‐keto prostaglandin F1αin vivo upon stimulation with zymosan. The maximum inhibition of eicosanoid synthesis was observed when the dietary DHA/LA ratio was 0.16 and no further inhibition occurred when the ratio was increased up to 0.81.
Effects of omega‐3 fatty acids on vascular smooth muscle cells: Reduction in arachidonic acid incorporation into inositol phospholipids
Authors: Yerram Nagender R. , Spector Arthur A.
Published: November 2006

A rapid increase in arachidonic acid incorporation into phosphatidylinositol (PI) occurred following exposure of cultured porcine pulmonary artery smooth muscle cells to calcium ionophore A23187. This response was specific for PI and phosphatidic acid; none of the other phosphoglycerides showed any increase in arachidonic acid incorporation. The incorporation of [3H]inositol also was increased, indicating that complete synthesis of PI rather than only fatty acylation occurred in response to the ionophore. The presence of omega‐3 fatty acids, especially eicosapentaenoic acid (EPA), reduced arachidonic acid but not inositol incorporation into PI. Stimulated incorporation of EPA also occurred under these conditions, suggesting that EPA replaces arachidonic acid in the newly synthesized pool of PI. Although much less arachidonic acid was incorporated into the polyphosphoinositides following exposure to the ionophore, arachidonic acid incorporation into these phosphorylated derivatives also decreased when EPA was present. These findings suggest that when omega‐3 fatty acids are available, less arachidonic acid is channeled into the inositol phospholipids of activated smooth muscle cells because of replacement by EPA. This may represent a mechanism whereby omega‐3 fatty acids, especially EPA, can accumulate in the metabolically active pools of inositol phospholipids and thereby possibly influence the properties or responsiveness of vascular smooth muscle.
Autoxidation of methyl linoleate initiated by the ozonide of allylbenzene
Authors: Ewing James C. , Cosgrove John P. , Giamalva David H. , Church Daniel F. , Pryor William A.
Published: November 2006

Allylbenzene ozonide (ABO), a model for polyunsaturated fatty acid (PUFA) ozonides, initiates the autoxidation of methyl linoleate (18∶2 ME) at 37°C under 760 torr of oxygen. This process is inhibited by d‐α‐tocopherol (α‐T) and 2,6‐di‐ert‐butyl‐4‐methylphenol (BHT). The autoxidation was followed by the appearance of conjugated diene (CD), as well as by oxygen‐uptake. The rates of autoxidation are proportional to the square root of ABO concentration, implying that the usual free radical autoxidation rate law is obeyed. Activation parameters for the thermal decomposition of ABO were determined under N2 in the presence of radical scavengers and found to be Ea=28.2 ±0.3 kcal mol−1 and log A=13.6±0.2; kd (37°C) is calculated to be (5.1±0.3)×10−7 sec−1. Autoxidation data are also reported for ozonides of 18∶2 ME and methyl oleate (18∶1 ME).
Gas chromatographic analysis of intact steryl esters in wild typeSaccharomyces cerevisiae and in an ester accumulating mutant
Authors: Fenner Gregeory P. , Parks Leo W.
Published: November 2006

The steryl ester faction from wild type and mutant strains of the yeastSaccharomyces cerevisiae was analyzed without saponification by a non‐polar capillary gas chromatographic column. When expressed as μg ester/mg dry wt, the total ester fraction remained constant or declined slightly from log to stationary phase in the wild type. In the mutant the decrease was more dramatic. No individual ergosteryl ester species was dominant throughout the culture cycle in the wild type. A compound tentatively identified as zymosteryl palmitate was the most prevalent ester in wild type log phase cells, ergosta‐5,7‐dienyl palmitate and ergosta‐5,7‐dienyl palmitoleate were the major esters in stationary cells. In the mutant strain, ergosteryl esters of palmitate, palmitoleate, oleate, and stearate were the major ester components throughout the culture cycle. Like the wild type, however, the mutant showed an increase in the proportion of ergosta‐5,7‐dienyl esters in the stationary phase of the culture cycle. The data did not indicate a sterol/fatty acid specificity during the culture cycle.
Novel branched‐chain fatty acids in certain fish oils
Authors: Ratnayake W. M. N. , Olsson B. , Ackman R. G.
Published: November 2006

Methyl‐branched fatty acids, which are usually minor components (≤0.1%) in fish oils, were concentrated in the non‐urea‐complexing fraction along with polyunsaturated fatty acids during the enrichment of omega‐3 fatty acids from certain fish oils via the urea complexation process. The methyl‐branched fatty acids in the omega‐3 polyunsaturated fatty acid concentrates, which were prepared from three fish body oils, were characterized by gas chromatography and gas chromatography/mass spectrometry. Among the major branched‐chain fatty acids expected and identified were the known isoprenoid acids—mainly 4,8,12‐trimethyltridecanoic, pristanic, and phytanic—and the well‐known iso and anteiso structures. Two novel phytol‐derived multimethyl‐branched fatty acids, 2,2,6,10,14‐pentamethylpentadecanoic and 2,3,7,11,15‐pentamethylhexadecanoic, were identified in redfish (Sebastes sp.) oil. These two fatty acids were absent in oils from menhaden (Brevoortia tyrannus) and Pacific salmon (mixed, but mostly from sockeye,Oncorhynchus nerka). The major branched‐chain fatty acid in the salmon oil, 7‐methyl‐7‐hexadecenoic acid, was also present to a moderate extent in menhaden oil. A novel vicinal dimethyl‐branched fatty acid, 7,8‐dimethyl‐7‐hexadecenoic was detected in all of the fish oils examined, but was most important in the salmon oil. Three monomethyl‐branched fatty acids, 11‐methyltetradecanoic acid, and 11‐ and 13‐methylhexadecanoic, hitherto undescribed in fish lipids, were also detected in salmon, redfish and menhaden oils.
HPLC method for quantitation of cholesterol and four of its major oxidation products in muscle and liver tissues
Authors: Csallany A. Saari , Kindom S. E. , Addis P. B. , Lee Joo‐Hee
Published: November 2006

A fast, sensitive, high performance liquid chromatographic method was developed for the quantitation of cholesterol and four of its major oxidation products: 3β‐hydroxycholest‐5‐en‐7‐one (7‐ketocholesterol), cholest‐5‐ene‐3β, 7α‐diol (7α‐hydroxycholesterol), cholest‐5‐ene‐3β,7β‐diol (7β‐hydroxycholesterol), and cholest‐5‐ene‐3β,25‐diol (25‐hydroxycholesterol). In this procedure 2∶1 chloroform:methanol (v/v) extracts of tissue homogenate were combined, dried over anhydrous Na2SO4, filtered, evaporated to dryness under N2 and dissolved with a mobile phase of either 97∶3 or 93∶7 hexane:isopropanol (v/v). After membrane filtration and without further purification, aliquots were directly injected onto a 10‐μm pore size, 30×0.39 cm μ‐Porasil normal phase column. The separation of cholesterol and its oxidation products was monitored by a UV detector at 206 and 233 nm. This method was successfully applied to pork muscle as well as mouse liver tissues and was able to detect cholesterol oxidation products (COP) in the ppm range. The identity of the COP was confirmed by mass spectroscopy.
HPLC analysis of desmosterol, 7‐dehydrocholesterol, and cholesterol
Authors: Goh Edward H. , Colles Scott M. , Otte Kimberly D.
Published: November 2006

A simple and sensitive method to analyzed mixtures of desmosterol, 7‐dehydrocholesterol and cholesterol is described. The method involves the oxidative conversion of the sterols with cholesterol oxidase, followed by high performance liquid chromatographic (HPLC) analysis. A C18 reversed phase column (3 μm, 75×4.6 mm) and a mixture of methanol and acetonitrile (1∶1, v/v) at a rate of 1 ml/min are used to separate the sterols. The eluted sterols are quantified by measuring UV absoprtion at 240 nm. As little as 10 pmoles of sterol can be quantified under these conditions.
Identification of cholesta‐7,24‐dien‐3β‐ol and desmosterol in hamster cauda epididymal spermatozoa
Authors: Awano M. , Kawaguchi A. , Morisaki M. , Mohri H.
Published: November 2006

The sterol composition of hamster cauda epididymal spermatozoa was remarkably different from that of several other mammalian spermatozoa. Desmosterol and cholesta‐7,24‐dien‐3β‐ol account for as much as 90% of the total sterols. Cholesterol and desmosterol are the major components of mouse cauda epididymal spermatozoa, and rabbit, boar and bull ejaculated spermatozoa. Cholesta‐7,24‐dien‐3β‐ol was not detected. Furthermore, cholesterol was the main sterol in hamster caput epididymal spermatozoa, while only a trace amount of desmosterol was detected and cholesta‐7,24‐dien‐3β‐ol was hardly detected at all. The sterol content of cauda and caput epididymal spermatozoa was 0.17±0.05 μmol/108 spermatozoa. During maturation, the desmosterol and cholesta‐7,24‐dien‐3β‐ol levels increase and the cholesterol level decreases. Cholesta‐7,24‐dien‐3β‐ol appears as a sterol in mature spermatozoa and seems to be a characteristic sterol of hamster cauda epididymal spermatozoa.
Interaction of potentially toxic bile acids with human plasma proteins: Binding of lithocholic (3α‐hydroxy‐5β‐cholan‐24‐oic) acid to lipoproteins and albumin
Authors: Malavolti Mauro , Fromm Hans , Ceryak Susan , Shehan Kathleen L.
Published: November 2006

The binding of lithocholic acid to different plasma fractions was studied. When whole plasma was incubated for 8 hr, approximately 25% of the incubated [14C]lithocholic acid was bound to the lipoprotein and lipoprotein‐free, albumin‐rich fractions. An average of 87.6% of the bound‐lithocholic acid was present in the lipoprotein‐free, albumin‐rich fraction, 7.2% in high density lipoproteins, 2.2% in low density lipoproteins, 1.0% in intermediate density lipoproteins and 2.0% in very low density lipoproteins. Expressed as binding per μg protein, considerably less [14C]lithocholic acid was bound to the lipoprotein‐free, albumin‐rich fraction, than to the lipoproteins. The binding of [14C]lithocholic acid after the incubation of the isolated plasma fractions was similar to that found after the incubation of whole plasma. The highest transfer of [14C]lithocholic acid occurred from the lipoprotein‐free, albumin‐rich fraction to the lipoprotein fractions. The studies indicate, that, although the largest amount of lithocholic acid is bound to the lipoprotein‐free, albumin‐rich fraction, per μg protein, the binding of lithocholic acid to lipoporteins is more pronounced and stable than that bound to the lipoprotein‐free, albumin‐rich fraction. Since lipoproteins, in contrast to albumin, are internalized by most tissues, they may be important carriers into cells of lithocholic acid and other potentially toxic or tumorigenic bile acids.
New phospholipid fatty acids from the Caribbean spongeEctyoplasia ferox
Authors: Carbelleira Néstor M. , Maldonado Marie E.
Published: November 2006

The phospholipid fatty acids from the Caribbean spongeEctyoplasia ferox were studied. The novel fatty acids 25‐methyl‐5,9‐heptacosadienoic (1) and 26‐methyl‐5,9‐heptacosadienoic (2) were identified in 3.4 and 2.0% abundance, respectively, representing the longest set of Δ5,9iso andanteiso acids yet isolated from a marine sponge. The new acid 10,13‐dimethyltetradecanoic (3), the unusual acid 15‐methyl‐11‐hexadecenoic (4) and the also novel acid 9‐methyl‐11‐hexadecenoic (5) were also identified inE. ferox. The principal sterols isolated fromE. ferox were 24‐ethylcholest‐5‐en‐3β‐ol (46%) and 24(R)‐methylcholesta‐5,22‐dien‐3β‐ol (14%).
Effect of pH on the affinity of phospholipids for cholesterol
Authors: Jacobsohn Myra K. , Bazilian Linda S. , Hardiman Janice , Jacobsohn Gert M.
Published: November 2006

The ability of multilamellar vesicles of phosphatidylcholine and phosphatidylethanolamine in aqueous phase to prevent access to cholesterol by a nonpolar solvent was examined. Phosphatidylethanolamine vesicles retained less sterol than phosphatidylcholine vesicles. In mixed vesicles, cholesterol was retained in proportion to the amount of phosphatidylcholine. To alter the charge and hydration of head groups, pH was adjusted from 1.2 to 12.5. Above pH 8, both phosphatidylethanolamine and phosphatidylcholine retained sterol in a 1∶1 molar ratio of phospholipid to cholesterol, regardless of acyl side chain composition. Between pH 2.0 and pH 8.0, sterol retention varied with type of head group and side chain. Lipids with 16‐carbon saturated side chains retained more sterol than 18‐carbon unsaturated or 12‐carbon saturated side chains. Between pH 1.1 and 2.0, none of the phosphatidylethanolamines retained sterol, but long chain phosphatidylcholines, saturated or unsaturated, retained sterol in a 1∶1 molar ratio of phospholipid to sterol. Short chain phosphatidylethanolamines and phosphatidylcholines retained 0 to 20% at the low‐ to mid‐pH range. Size of multilamellar vesicles, measured by Doppler effect light scattering analysis, had no bearing on sterol retention. Sonication of vesicles, which increases surface curvature, increases the retention of sterol. Fluorescence polarization indicated that cholesterol does not interact with DPPC or DLPC side chains. The observations can be interpreted in terms of space requirements of head groups, including charge repulsion and hydration. Other factors, such as monovalent cation replacement by protons, juxtaposition of charged groups on vesicle surfaces and length and unsaturation of acyl side chains affect the affinity of phospholipids for cholesterol.
Δ6 and Δ5 desaturase activities in liver from obese zucker rats at different ages
Authors: Blond Jean‐Paul , Henchiri Cherifa , Bézard Jean
Published: November 2006

Δ6 Desaturation of linoleic acid (18∶2 n−6) and Δ5 desaturation of dihomo‐γ‐linolenic acid (20∶3 n−6) were measured in liver microsomes from genetically obese Zucker rats (fa/fa) and from their lean littermates (Fa/−). Both groups were fed a balanced commercial diet. The rats were 6, 9 and 12 weeks old, which corresponded to stages in their active growth period. The content of total fatty acids and n−6 polyunsaturated fatty acids in whole liver and liver microsomes was also determined in order to ascertain how the desaturase activities measuredin vitro reflected regulation of essential fatty acid metabolismin vivo. Contrary to values obtained for Δ6 desaturation, Δ5 desaturation at nonsaturating substrate levels were lower in obese rats than in lean controls. In contrast, at saturating substrate level, the maximal Δ5 desaturase activities were the same in both phenotypes and they increased with age. Study of Δ5 desaturation kinetics (1/V vs 1/S) showed that Vm did not differ between 12‐week‐old obese and lean rats, whereas KM in obese rats was much lower than in controls, expressing the very low affinity of the enzyme for the substrate in obese animals. The fatty acid composition of liver lipids reflected the results of desaturase activitiesin vitro. In particular, the ratios 20∶4 n−6/20∶3 n−6 were lower in obese rats than in lean rats, which can be explained by the lower conversion of 20∶3 n−6 into 20∶4 n−6 by Δ5 desaturation. However, the total amount of 20∶4 n−6 in the whole liver did not differ between phenotypes, whatever their age. This work presents evidence for a relationship between the changes in fatty acid compositional data in hepatic total lipids, total lipids of liver microsomes and modifications of fatty acid desaturase activities in the genetically obese Zucker rat.
Molecular species of glycerophospholipids and sphingomyelins of human plasma: Comparison to red blood cells
Authors: Myher J. J. , Kuksis A. , Pind S.
Published: November 2006

In addition to diacyl glycerophosphocholine and sphingomyelin, human plasma also contains small amounts of other glycerophospholipids, which may have special metabolic function. The structure and origin of these minor plasma lipids has not been determined. Knowledge of the detailed composition of the phospholipids of red blood cells (Myheret al., Lipids 24, 1989) permits evaluation of one of the possible sources. This study reports the detailed analyses of plasma glycerophospholipids made in parallel to those of the erythrocyte lipids obtained from the same blood using HPLC and GLC methods. The proportions of the major phospholipid classes in the plasma and erythrocytes were similar to published values, including the essential absence of diradyl glycerophosphoserine from plasma. Plasma diradyl glycerophosphocholine contained 93.0% diacyl, 3.4% alkylkacyl and 3.6% alkenylacyl, whereas the diradyl glycerophosphoethanolamine consisted of 71.8% alkenylacyl, 19.9% diacyl and 8.3% alkylacyl subclasses. The diradyl glycerophosphoinositol was 100% diacyl. The content of the minor subclasses of plasma diradyl glycerophosphocholine is similar to that of the red cells, but the ether content of the diradyl glycerophosphoethanolamine is higher in plasma than in cells. The lipid ether subclasses of plasma glycerophospholipids also contained a higher proportion of the C20, C22 and C24 alkyl and alkenyl chains than those of the cells. Furthermore, the C16 and C18‐containing species in diradyl glycerophosphoethanolamine subclasses varied with the nature of the polyunsaturated acid, whereas in diradyl glycerophosphocholine subclasses the polyunsaturated acids were combined with the C16 and C18 acids in equal proportions. The significant differences in the molecular species of glycerophospholipids and sphingomyelin between plasma and red cells would appear to limit any direct transfer or equilibration of their lipid components.
Modulating influence of dietary lipid intake on the prostaglandin system in adult men
Authors: Ferretti Aldo , Judd Joseph T. , Taylor Philip R. , Schatzkin Arthur , Brown C.
Published: November 2006

We evaluated the effect of moderate dietary changes on the prostaglandin system by measuring the urinary excretion of 7α‐hydroxy‐5,11‐dioxo‐tetranorprostane‐1,16‐dioic acid (PGE‐M). In a crossover design, twenty‐four free‐living male subjects in good health (24 to 54 years of age) were fed two diets: (i) Regular (R) diet, 41% energy (en%) from fat, P/S 0.59, M/S 0.96; (ii) Experimental (E) diet, 19 en% from fat, P/S 1.31, M/S 1.48. Diet R contained 13.9 g/day of neutral detergent fiber (NDF) and about 600 mg/day of cholesterol per 3200 kcal; Diet E contained 35.5 g/day NDF and about 280 mg/day cholesterol. Each controlled‐diet period lasted ten weeks. The menu cycle was 7 days, and all diets were calculated to provide adequate amounts of essential nutrients. The PGE‐M excretion rates were determined in 24‐hr urine by stable‐isotope dilution gas chromatography‐mass spectrometry in the selected ion‐monitoring mode. Low‐fat Diet E, with an intake of 6.6 en% from polyunsaturates, was associated with an average 14.2% reduction in PGE‐M daily output, compared to high‐fat Diet R with a 9.3 en% from polyunsaturates (P=0.046). These results support the view that dietary lipid changes can significantly alter thein vivo production of E‐series prostaglandins. We cannot conclude, however, if this apparent diet effect was brought about by the change in linoleate intake alone or was the result of complex biochemical interactions among individual fatty acids, both saturated and unsaturated.
Synthesis and lipase catalyzed hydrolysis of thiolesters of 2‐, 3‐ and 4‐methyl octanoic acids
Authors: Sonnet Philip E. , Baillargeon Mary Welch
Published: November 2006

Racemic 2‐, 3‐ and 4‐methyloctanoic acids were synthesized. The 2‐mercaptoethanol S‐esters of these branched acids, and of octanoic acid, were exposed to lipases of the fungiCandida rugosa andAspergillus niger. Reactions were followed spectrophotometrically using Ellman's Reagent. Branching at the 3‐position retards lipolysis more severely than at either the 2‐ or 4‐positions. Features of the assay method are discussed with reference to titrimetry.