bluuebunny/crossref_metadata_2025 huggingface dataset:
Generation of phospholipid artefacts during extraction of developing soybean seeds with methanolic solvents
Authors: Roughan P. G. , Slack C. R. , Holland R.
Published: November 2006

The major phospholipids of soybean cotyledons during development were phosphatidylcholine (45–55%), phosphatidylethanolamine (24–28%), and phosphatidylinositol (15–18%) when the tissue was steam‐killed prior to extraction of the lipids. The only other phospholipids of any significance (4–6%) was identified as phosphatidylglycerol. Phosphatidic acid was a minor constituent (<1%), and neither N‐acyl phosphatidylethanolamine norbis‐phosphatidic acid were detected in appreciable (>0.1% of the total lipid phosphorus) quantities. When fresh cotyledons were rapidly homogenized in mixtures of chloroform and methanol or in methanol alone, phosphatidylmethanol was formed in variable amounts (0–20% of the total phospholipid), and when cotyledons were soaked in methanol prior to homogenizing, phosphatidylmethanol became the major phospholipid, accounting for up to 75% of the total lipid phosphorus. Phosphatidylmethanol was formed by the phospholipase D‐catalyzed transphosphatidylation of phosphatidylcholine and phosphatidylethanolamine during extraction.
13C Nuclear magnetic resonance spectroscopy of cyanolipids and cyanolipid‐containing seed oils
Authors: Mikolajczak K. L. , Weisleder D.
Published: November 2006

13C nuclear magnetic resonance (NMR) signals of all carbon atoms of the hydroxynitrile moieties on which cyanolipids are based have been assigned. The four known types of cyanolipids can be conveniently distinguished and identified by13C‐NMR whether they are in pure form or in unfractionated seed oils from which they are derived.
The effect of dietary fats on the plasma lipid composition of sheep
Authors: Noble R. C. , Vernon R. G. , Christie W. W. , Moore J. H. , Evans A. J.
Published: November 2006

This study reports on the plasma lipid compositions of sheep fed either a control diet (C), a control diet supplemented with tallow (A) or polyunsaturated fatty acid (B) that had been protected against hydrolysis and hydrogenation in the rumen, or a control diet supplemented with maize oil (D). Diet B considerably increased the 18∶2 content of all the major plasma lipid fractions. Although the feeding of diet D also resulted in an increase in the 18∶2 contents within the cholesteryl ester, unesterified fatty acid, and phospholipid fractions the increases were considerably less than those observed with diet B; the levels of 18∶2 within the triglyceride fraction remained similar to that for the sheep which received the control diet. The effect of feeding diet A was confined solely to the triglyceride fraction where the concentrations of 16∶0 and 18∶1 were increased. The lipoproteins of the plasma were separated into very low density lipoproteins (d<1.006), low density lipoproteins (1.006<d<1.063), and high density lipoproteins (1.063<d<1.21), and the distribution of the major lipids between these lipoprotein fractions was investigated. Diet B increased considerably the proportion of triglyceride found in association with the very low density fraction and the concentrations of 18∶2 within all the lipoprotein fractions; these increases in the concentrations of 18∶2 were not confined to any particular lipid fraction of the lipoproteins. In contrast, the increases in the concentrations of 18∶2 produced as a result of feeding diet D were confined to the low and high density lipoproteins. The effect of feeding diet A was confined to fatty acid changes within the triglycerides of the low and very low density lipoproteins.
Sterol mutants ofSaccharomyces cerevisiae: Chromatographic analyses
Authors: Bard M. , Woods R. A. , Barton D. H. R. , Corrie J. E. T. , Widdowson D. A.
Published: November 2006

The sterols accumulated by ergosterol deficient mutants of the geneserg6, erg2, erg3, anderg5 (formerlypo11, po12, po13, andpo15) have been analyzed by gas liquid chromatography. Together with pure sterols obtained from the mutants, they were characterized on SE‐30, OV‐17, and OV‐225. The effects of molecular structure on the retention characteristics of a range of C28 ergostane sterols have been studied. The double mutants obtained by crossing the single mutants were also analyzed and their sterols identified where possible. The effects of theerg mutations on the control of sterol biosynthesis in yeast are discussed.
Metabolism of arachidonate and stearate injected simultaneously into the mouse brain
Authors: Sun Grace Y.
Published: November 2006

The metabolism of a polyunsaturated and a saturated fatty acid in brain membrane phosphoglycerides was examined by injecting simultaneously a mixture of14C‐arachidonate and3H‐stearate into the mouse brain and isolating the microsomal and synaptosomal fractions at 1–40 min after injections. Both types of labeled fatty acids were utilized more readily in the microsomal than the synaptosomal fractions in brain. However, labeled arachidonate was incorporated more rapidly into membrane phosphoglycerides than was stearate. In both subcellular fractions, the relative specific radioactivity (3H and14C) of diacyl‐glycerophosphorylinositol (diacyl‐GPI) was higher than other types of phosphoglycerides such as diacyl‐glycerophosphorylcholine (diacyl‐GPC) and diacyl‐glycerophosphorylethanolamine (diacyl‐GPE). Furthermore, the apparent rates of incorporation of radioactivity into diacyl‐GPI was more rapid for the14C‐arachidonate than for the3H‐stearate. Results of the experiment have demonstrated obvious differences in metabolism between stearate and arachidonate in brain. The more rapid transfer of arachidonate to diacyl‐GPI is probably due to the presence of an acyl transferase system specially active for the transfer of arachidonyl groups to diacyl‐GPI.
cis‐Enediyne chromophore of isano oil
Authors: Miller Roger W. , Weisleder David , Plattner Ronald D. , Smith C. R.
Published: November 2006

The nonpolar fatty acids from isano oil have been reinvestigated to determine the source of the UV absorption long attributed to conjugatedcis‐enediyne groupings. Proton magnetic resonance and mass spectra of certain fractions supported the occurrence of such structures, but discrete compounds with this grouping were not isolated. Part of this ubiquituous UV absorption ascribed to enediyne was found to be due instead to the same conjugated diynones identified previously in the oxygenated acid fraction of isano oil. The structures of methyl octadeca‐9,11‐diynoate and methyl isanate were correlated with their proton magnetic resonance, (PMR), carbon‐13 magnetic resonance, and mass spectra.
Effects of cyanide on peanut lipoxygenase
Authors: St. Angelo Allen J. , Kuck James C.
Published: November 2006

Acidic and alkaline lipoxygenase isozymes were separated and assayed for activity while incubated in the presence of various concentrations of cyanide. Inhibition due to cyanide per se was not found. Instead, cyanide caused an increase in pH, which decreased the activity of the acidic isozyme to a rate corresponding to the same pH on the activity curve for the cyanide‐free reaction.
Trans fatty acids: Positional specificity in brain lecithin
Authors: Karney Rona I. , Dhopeshwarkar Govind A.
Published: November 2006

Fifteen‐day‐old rats were divided into three groups: one group received an intracerebral injection of 5 μ Ci of 9‐trans, 12‐trans [1‐14C] octadecadienoic acid; the second group was given 5 μCi of the same compound plus an equal wt of nonradioactive allcis arachidonic acid; the third group was given 5 μCi of 9‐trans [1‐14C] octadecenoic acid. All animals were sacrificed 8 hr after injection. Glycerophosphocholine (GPC) was isolated and partically deacylated with phospholipase A2 fromCrotalus Adamanteus venom. The results of this study were as follows: 1) aftert [1‐14C] 18∶1 injection, there was twice as much radioactivity in the 1‐position as in the 2‐position; 2) whentt [1‐14C] 18∶2 was injected, more than 90% of the total radioactivity was found in the 2‐position; 3) followingtt[1‐14C]‐18∶2 +nonradioactive arachidonate injection, ca. 75% of the total radioactivity still remained in the 2‐position; and 4) all of the injected [1‐14C]‐tracers showed evidence of undergoing β‐oxidation to form acetyl‐CoA, which was converted to radioactive palmitate. The possibility is discussed that the observed distribution pattern of the injected radioactive tracers may be attributed to tissue metabolic specificity. Ramifications of the deposition of dietarytrans fatty acids in the brain during the developmental stage of the central nervous system are also discussed.
A comparative study of the lipid composition of isolated rat sertoli and germinal cells
Authors: Beckman J. K. , Coniglio J. G.
Published: November 2006

The lipid composition of enriched preparations of sertoli cells and of germinal cells, isolated from the testes of mature rats, has been investigated. Sertoli cells contained a much lower content of phospholipids (in particular, much less phosphatidylcholine and phosphatidylethanolamine) and a higher content of triacylglycerols than did germinal cells. In addition, the Sertoli cells had a higher ratio of esterified to unesterified cholesterol than did germinal cells. Total lipids of Sertoli cells contained considerably lower levels of palmitic and docosa‐4,7,10,13,16‐pentaenoic acids and higher levels of stearic and oleic acids than did the total lipids of germinal less palmitic and docosa‐4,7,10,13,16‐pentaenoic acids, more stearic and oleic acids and also more arachidonic acid than did the corresponding lipid classes of the germinal cells. Minor differences between cell types were also noted for the content of palmitoleic, linoleic, docosa‐7,10,13,16‐tetraenoic, docosa‐4,7,10,13,16,19‐hexaenoic and tetracosa‐9,12,15,18‐tetraenoic acids.
Sterols and fatty acids ofEpifagus virginiana, a nonphotosynthetic angiosperm
Authors: Nes W. David , Patterson Glenn W. , Southall M. Anne , Stanley June L.
Published: November 2006

The sterol and fatty acid compositions ofEpifagus virginiana, which is a nonphotosynthetic flowering plant, have been examined by combined gas liquid chromatography‐mass spectrometry (GLC‐MS) and nuclear magnetic resonance (NMR). The organism exhibited a typical higher plant Δ5‐sterol profile with the C‐24 alkyl group oriented “α” for the major sterol Trace amounts of 24‐methylenecycloartanol and cycloeucalenol established connection with the first cyclic intermediate (cycloartenol) in photosynthetic plant sterol biosynthesis. In a separate in vitro experiment, excised root and stem tissue were incubated with two labeled triterpenoid precursors, [2‐3H] lanosterol and [2‐3H]cycloartenol. Both the radioactive compounds were converted to labeled [3H]sitosterol indicating the presence of an active biosynthetic pathway inEpifagus. Characteristic photosynthetic higher plant fatty acids were also present, and the polyenic acid was identified as α‐linolenic acid.
Metabolism of naphthenic hydrocarbons. Utilization of a monocyclic paraffin, dodecylcyclohexane, by rat
Authors: Tulliez Jacques E. , Bories Georges F.
Published: November 2006

3H‐Dodecylcyclohexane was incorporated in rat diet in order to study the metabolic utilization by mammals of a monocycloparaffin chosen as a typical naphthenic constituent of mineral oils. Dodecylcyclohexane was largely absorbed. No elimination of the hydrocabon was observed in urine while an extended excretion of3H occurred via this route. About 7% of absorbed dodecylcyclohexane was stored in the carcass, while the rest was ω‐oxidized to cyclohexyldodecanoic acid, which incorporated into neutral lipids and phospholipids. The aliphatic chain of this unusual fatty acid underwent the normal fatty acid degradation pathways, leading to even fatty acids, squalene, cholesterol and nonlipid resynthesis, while the cyclohexyl ring was eliminated as urinary metabolites. Incorporation of ω‐cyclohexyl fatty acids in phospholipids may raise a point of toxicological significance which is to be investigated.
Distribution of hydrocarbons in bovine tissues
Authors: Lintas C. , Balduzzi A. M. , Bernardini M. P. , Di Muccio A.
Published: November 2006

Liver, heart, kidneys, muscle and adipose (perirenal and subcutaneous) tissues were collected from six animals for analysis of their hydrocarbon composition. Qualitative and quantitative determinations were carried out by gas chromatography and combined gas chromatography‐mass spectrometry. Although differing in the proportions, a homologous series of n‐alkanes ranging from n‐C12 to n‐C31 was found in all the samples examined. The isoprenoid hydrocarbons phytane and phytene (phyt‐1‐ene and phyt‐2‐ene) were also identified.
Reaction of thiobarbituric acid with saturated aldehydes
Authors: Kosugi Hiroko , Kikugawa Kiyomi
Published: November 2006

The reaction of thiobarbituric acid (TBA) with saturated aldehydes, i.e., 1‐butanal, 1‐hexanal and 1‐heptanal, produced a 455‐nm yellow and a 532‐nm red pigment. Formation of the pigments depended on the reaction conditions. The yellow pigment was unstable in the presence of excess amounts of the saturated aldehydes. The red pigment was formed only when the reaction was performed at a TBA/aldehyde ratio of 1∶1 in aqueous acetic acid. Formation of the yellow and red pigments required molecular oxygen. The colorless adducts, intermediates for the yellow and the red pigments, were isolated from the reaction mixtures. Aldol condensation and dehydration of 2 mol of the saturated aldehydes initially gave the α,β‐unsaturated aldehydes, which in turn reacted with TBA to form the colorless adducts, pyranopyrimidine derivatives. The adducts were then converted into the yellow and red pigments under aerobic conditions.
Absorption and distribution of deuterium‐labeledtrans‐ andcis‐11‐octadecenoic acid in human plasma and lipoprotein lipids
Authors: Emken E. A. , Rohwedder W. K. , Adlof R. O. , DeJarlais W. J. , Gulley R. M.
Published: November 2006

Triglycerides of deuterium‐labeledtrans‐11‐,trans‐11‐cis‐11‐ andcis‐9‐octadecenoic acid (11t‐18∶1‐2H, 11c‐18∶1‐2H) were simultaneously fed to two young adult male subjects. Plasma lipids from blood samples collected periodically for 48 hr were analyzed by gas chromatography‐mass spectroscopy. The results indicate (i) the Δ11‐18∶1‐2H acids and 9c‐18∶1‐2H were equally well absorbed; (ii) relative turnover rates were higher for the Δ11‐18‐1‐2H acids in plasma triglycerides; (iii) incorporation of the Δ11‐18∶1‐2H acids into plasma phosphatidylcholine was similar to 9c‐18∶1‐2H, but distribution at the 1‐and 2‐acyl positions was substantially different; (iv) esterification of cholesterol with 11t‐18∶1 was extremely low; (v) chain shortening of the Δ11‐18∶1‐2H acids was 2–3 times greater than for 9c‐18∶1‐2H; (vi) no evidence for desaturation or elongation of the 18∶1‐2H acids was detected; and (vii) a 40% isotopic dilution of the 18∶1‐2H acids in the chylomicron triglyceride fraction indicated the presence of a substantial intestinal triglyceride pool. Based on our present knowledge, these metabolic results for Δ11‐18∶1 acids present in hydrogenated oils and animal fats indicate that the Δ11 isomers are no more likely than 9c‐18∶1 to contribute to dietary fat‐related health problems.
Correlation between skeletal muscle free fatty acid extraction and vascular decompensation during hemorrhagic hypotension
Authors: Bond Robert F. , Zepp Andrew , Peissner Lorraine C. , Manning Eva S.
Published: November 2006

The objective of this study was to determine whether or not a relationship exists between free fatty acid (FFA) extraction by skeletal muscle and onset of irreversible shock. Hind limb skeletal muscle vasculature of anesthetized dogs was surgically isolated from cutaneous tissue and subjected to a modified Wigger's hemorrhage shock protocol which was divided into five stages (I−V). Since the first signs of irreversibility began in Stage II, this stage of hypovolemic hypotension was subdivided into IIa, IIb and IIc. Arterial and venous blood samples were taken during each stage for subsequent blood gas and FFA analysis. The data indicated that the onset of severe tissue ischemia and metabolic acidosis occurs concurrently with increased uptake of FFA and skeletal muscle vasodilation (decomposition). A possible physiological explanation for these observations could be related to an increased synthesis and release of PGE1. This agent has been shown by others to inhibit adrenergic neurotransmitter release causing loss of vascular tone.
Membrane lipids in bromodeoxyuridine‐differentiated astroglial cells in culture
Authors: Robert J. , Mandel P. , Rebel G.
Published: November 2006

Embryonic hamster astroblasts (NN strain) grown in continuous line were cultivated in the presence of bromodeoxyuridine (BrdU). A decrease in the growth rate of the cells and striking changes in their morphology were observed, the morphology of the cells resembling that of mature astrocytes. Membrane lipids of BrdU‐differentiated and standard cells were compared. No modification of the lipid/protein ratio was observed. Phospholipids and cholesterol were increased in the same proprotions in the cells, and no modification of the phospholipid distribution was observed. Ganglioside sialic acid remained at the same level, but the ganglioside distribution was highly modified. Complex gangliosides appeared (GM1 and GD1a), while the proportion of simple gangliosides (GM3 and GD3) decreased. However, neither GT1 nor GQ1 were detected in differentiated cells. The distribution of phosphoglyceride acyl groups was highly modified, the proportion of arachidonic and docosapentaenoic acids being 2 to 3 times higher in BrdU‐treated cells than in proliferating ones. These results were compared to those obtained with another clonal line of glial cells (C6) which exhibited no morphological differentiation in the presence of BrdU; the lipids of these cells were not modified by such a treatment.
Composition of wax esters and triacylglycerols in the melon and blubber fats of a young Sowerby's whaleMesoplodon bidens
Authors: Lok C. M. , Folkersma B.
Published: November 2006

The blubber fat of a yearling Sowerby's Whale,Mesoplodon bidens, stranded on the Dutch coast, contained 59% triacylglycerols. This is quite unexpected because low levels (0–6%) of triacylglycerols are characteristic ofZiphiidae whales. In addition, the chain lengths of the fatty acids of the melon were longer than those of previously studied related species. As young Sowerby's Whales undergo a change in diet from mainly triacylglycerols in milk to wax ester containing food during their development from infancy to independence, these findings could reflect the age of the animal.
Composition of plasma and nascent very low density lipoprotein from perfused livers of hypercholesterolemic squirrel monkeys
Authors: Nicolosi R. J. , Hayes K. C.
Published: November 2006

The composition of circulating very low density lipoprotein (VLDL) was compared with the composition and secretion of nascent VLDL from perfused livers of squirrel monkeys that were fed unsaturated or saturated fat diets to elicit different degrees of plasma hypercholesterolemia. All squirrel monkeys studied had cholesteryl ester‐rich plasma VLDL, although greater enrichment occurred in hypercholesterolemic animals fed saturated fat. Livers from hypercholesterolemic animals were capable of secreting VLDL particles enriched in cholesteryl ester, suggesting hepatic origin for a portion of this circulating lipid moiety. Total VLDL lipid, but not protein output by perfused livers of hypercholesterolemic monkeys, was greater than that by livers from hypocholesterolemic animals. These results indicate that saturated fat‐induced hypercholesterolemia is associated with changes in the composition of hepatic VLDL in the squirrel monkey.
Inhibition of rat hepatic sterol formation from squalene by plasma lipoproteins
Authors: Srikantaiah M. V. , Lew D. W. , Morin R. J.
Published: November 2006

The conversion of3H‐squalene to sterols by rat liver microsomes and cytosol was inhibited by individual rat and human plasma lipoproteins at various concentrations. This inhibition was also observed with added human high density apolipoprotein, but triglycerides, cholesterol or cholesteryl esters had no inhibitory effects. Lipoproteins and apo high density lipoprotein (HDL) were demonstrated to bind3H‐squalene in vitro. The binding of3H‐squalene by apo HDL could be reversed by increasing concentration of liver cytosol containing sterol carrier protein.
The use of 13‐methyltetradecanoic acid as an indicator of adipose tissue turnover
Authors: Klein Roger A. , Halliday David , Pittet Philippe G.
Published: November 2006

We show in this paper that 13‐methyltetradecanoic acid (13‐MTD) can be used as a structurally labeled marker for investigating the mobility of fatty acyl chains in adipose tissue in the rat. The presence of an ω‐1 methyl group allows easy quantitation by gas liquid chromatography (GLC) and permits an assessment to be made of any oxidation and chain elongation reactions with reincorporation of the label into the adipose tissue, since the iso‐acyl chain is well resolved from odd or even‐numbered homologous fatty acids with straight chains. The kinetics of uptake and loss of the structural label were different for adipose tissue taken from the various sites which were sampled, namely post abdominal, mesenteric, perirenal, pericardiac and subcutaneous adipose tissue as well as the epidydimal fat pads. We also report preliminary results in man which confirm that the method is applicable to human clinical studies and that 13‐MTD kinetics differ for adipose tissue taken from the 3 different subcutaneous sites‐waist, arm and thigh.
Quantitative analyses of hydroxystearate isomers from hydroperoxides by high pressure liquid chromatography of autoxidized and photosensitized‐oxidized fatty esters
Authors: Neff W. E. , Frankel E. N.
Published: November 2006

A high pressure liquid chromatography (HPLC) method is described for the determination of the isomeric hydroxysterates from hydroperoxides of oxidized fatty esters. The samples are hydrogenated and the mixtures of hydroxystearates are concentrated by partial removal of unoxidized esters and complete removal of polar materials. Isomeric hydroxystearates are then separated on a porous microparticulate adsorption (10 μ) column and elution with 0.25% isopropyl alcohol inn‐hexane is monitored at 212 nm. The 8‐OH, 9‐OH, 10‐OH, 11‐OH and 16‐OH isomers were completely separated, but the 12‐OH, 13‐OH and 15‐OH were only partly resolved by HPLC. The relative percentages of isomeric hydroxy esters were analyzed quantitatively by a computer integration method. Accuracy of the method was checked with known mixtures of synthetic hydroxystearates. The isomeric hydroperoxide composition of oxidized methyl oleate, linoleate, linolenate and soybean methyl esters determined by HPLC were in good agreement with previous analyses by gas chromatography‐mass spectrometry.
Species variation in serum levels of prostaglandins and their precursor acids
Authors: Hwang D. W. , Godke R. A. , Rings R. W.
Published: November 2006

Levels of prostaglandin (PG) precursor acids, and PGE2, PGF2α and TXB2 in sera of adult animals (5/species) were determined by gas chromatography and radioimmunoassay, respectively. The level of arachidonic acid in horse serum lipids was the lowest (0.61±0.03%), and that in dog serum lipids was the highest (18.1±1.8%). Bovine serum lipids contained considerable amounts of 20∶3ω6 (precursor of monoene PG) and 20∶5ω3 (precursor of triene PG) in addition to arachidonic acid. Thromboxane B2 was not the major species of endoperoxide metabolite synthesized by platelets from arachidonic acid in male ruminants and pig. The concentration of TXB2 in the serum of the lactating cow was more than 50 times greater than that of ovariectomized cows or of bulls. Although TXB2 was the major species of endoperoxide metabolite synthesized by human platelets, its serum concentration was much lower than that of nonruminant animals except the pig. These results showed that there were considerable variations in levels of PG and their precursors among various species of animals. The species variation in PG and TXB2 concentrations was not simply attributed to the differences in platelet concentration blood.
Effects of different dietary intake of essential fatty acids on C20∶3ω6 and C20∶4ω6 serum levels in human adults
Authors: Lasserre M. , Mendy F. , Spielmann D. , Jacotot B.
Published: November 2006

Four diets which differed in fatty acid composition were provided for five months each to a group of 24 healthy nun volunteers. The diets contained 54% carbohydrates, 16% proteins and 30% lipids. One‐third of the lipid part remained unchanged during the whole study, and two‐thirds were modified during each period. For this latter portion, one of the following dietary fats was used: sunflower oil, peanut oil, low erucic acid rapeseed (LEAR) oil or milk fats. This procedure allowed an evaluation of the effects of various amounts of dietary linoleic acid (C18∶2ω6) and alpha‐linolenic acid (C18∶3ω3) on the serum level of their metabolites. A diet providing a large amount of linoleic acid (14% of the total caloric intake) resulted in low levels of dihomo‐gamma‐linolenic acid (C20∶3ω6) and arachidonic acid (C20∶4ω6) in serum phospholipids and cholesteryl esters. A diet providing a small amount of linoleic acid (0.6% to 1.3% of the total caloric intake) induced high levels of ω6 fatty acid derivatives. Intermediate serum levels of C20∶3ω6 and C20∶4ω6 were found with a linoleic acid supply of about 6.5% of the total caloric intake. Serum levels of ω6 metabolites were not different after two diets providing a similar supply of C18∶2ω6 (4.5% to 6.5% of the total caloric intake), although in one of them the supply of C18∶3ω3 was higher (1.5% for LEAR oil versus 0.13% for peanut oil).

Under our experimental conditions (healthy human adults fed on a normo‐caloric diet with 30% lipids), we tried to determine PUFA (linoleic and linolenic acid) allowances which should be recommended for adults. The aim of the study was to obtain a hypocholesterolemic or normocholesterolemic effect while keeping normal 20∶3ω6 and 20∶4ω6 serum levels which would evidence a normal linoleic acid metabolism. The amounts recommended are: linoleic acid 5 to 6% of the total calories; alpha‐linolenic acid 0.5 to 1% of the total calories.
Hydrolysis of 4‐methylumbelliferyl butyrate: A convenient and sensitive fluorescent assay for lipase activity
Authors: Roberts Ingram M.
Published: November 2006

A rapid, sensitive and convenient fluorescent assay was developed to screen for lipase activity. The non‐fluorescent substrate, 4‐methylumbelliferyl butyrate (4‐MUB), solubilized in either liposomal dispersions or bile salt/lecithin mixed micelles, is hydrolyzed to butyric acid and the highly fluorescent compound, 4‐methylumbelliferone (4‐MU). Assays are run at 37 C for 10 min, terminated, and the changes in fluorescence quantitated with a Turner III fluorometer. Both lingual and pancreatic lipases exhibit activity against this artificial substrate. The assay has several advantages: nmoles 4 MU/ml/hr are measured allowing the detection of very low lipolytic activity; multiple samples may be simultaneously assayed, and only a brief incubation period is required.
Pulmonary lipid peroxides and fatty acids of rats fed different lipids and exposed to oxygen at hyperbaric pressure
Authors: Alam Syed Q. , Alam Bassima S.
Published: November 2006

Semipurified diets containing different lipids were fed to rat dams during lactation and subsequently to their pups for 33 weeks post‐weaning. Some rats within each group were exposed to oxygen at hyperbaric pressure (OHP). Lipid peroxide levels were lower in lungs of rats fed 7% hydrogenated coconut oil or 10% butter as compared with their controls, fed 7% corn oil or 10% safflower oil, respectively. Exposure to OHP increased lung peroxide levels. This increase varied with the type of fat in the diet. Studies of the fatty acid composition indicate that lipid peroxide levels generally increased with an increase in the levels of 18∶2 in lung total lipids. The results suggest that the type of dietary lipid may alter the susceptibility of the animal to pulmonary oxygen toxicity.
Increases in serum sphingomyelin by 17β‐estradiol
Authors: Merrill Alfred H. , Wang Elaine , Innis Wendy S. A. , Mullins Richard
Published: November 2006

The effects of estrogens on plasma sphingomyelin and the hepatic activity of the initial enzyme of sphingomyelin synthesis were examined using immature chicks. After three days of 17β‐estradiol administration, serum sphingomyelin, total phospholipids, and cholesterol doubled, and triacylglycerol levels increased 7.5 fold. The sphingomyelin content and percentage of total phospholipids of liver were unaffected by estrogen treatment. The specific activity of serine palmitoyltransferase (EC 2.3.1.50) was unchanged, but the total activity appeared slightly higher due to increased liver weights. The higher spingomyelin may, therefore, be due less to increased levels of biosynthetic enzymes than to factors such as the substrate (i.e., fatty acid) supply or decreased clearance of plasma sphingomyelin. These results are similar to earlier findings with key enzymes of cholesterol and glycerolipid biosynthesis and suggest that the three lipid pathways may be coordinated during estrogen treatment and enhanced very‐low density lipoprotein (VLDL) synthesis.
Stimulation of a neutral triacylglycerol hydrolase from rat heart by phosphatidylethanolamine and lysophosphatidylethanolamine
Authors: Severson David L. , Hurley Brenda
Published: November 2006

Triacylglycerol hydrolase activity measured at pH 7.5 in a pH 5.2 precipitate fraction from rat heart was increased two‐to three‐fold by the presence of phosphatidylethanolamine (PE) or lysophosphatidylethanolamine (LPE). This stimulatory effect also could be obtained in assays with particulate and soluble subcellular fractions and was observed with two different methods of preparing triolein substrate emulsions. Ethanolamine and glycerophosphorylethanolamine had no effect on hydrolase activity, whereas phosphatidylcholine (PC) and acidic phospholipids such as cardiolipin were inhibitory. Palmitic acid, palmityl CoA and palmityl carnitine inhibited PE‐stimulated hydrolase activity, but ethyl esters of palmitate had no effect. The preparation of acetone‐ether powders resulted in a marked reduction of triacylglycerol hydrolase activity, but PE and LPE now stimulated hydrolase activity by ten‐fold or greater, suggesting that these phospholipids may have an obligatory role in modulating triacylglycerol hydrolase activity. Triton X‐100 also stimulated hydrolase activity in acetone‐ether powders.
Altered arachidonic acid content in polymorphonuclear and mononuclear cells from patients with allergic rhinitis and/or asthma
Authors: Rocklin Ross E. , Thistle Lori , Gallant Leo , Manku M. S. , Horrobin David
Published: November 2006

We previously have found that monocytes from patients with allergic rhinitis and/or asthma produce less PGE2 than cells from normal subjects in response to a histamine‐induced lymphokine. In order to investigate this observation further, we measured the fatty acid content in the total phospholipids derived from the plasma, red cells, buffy coat cells, neutrophils, monocytes and lymphocytes of 27 allergic patients and 21 normal controls. There were no substantial differences between atopics and normals in the fatty acid analyses carried out for plasma and red cells. However, linoleic acid (18∶2n−6) levels were elevated significantly in the buffy coat fraction, while arachidonic acid (20∶4n−6) levels were reduced. Measurement of fatty acid levels after fractionation of the buffy coat population into neutrophils and monocytes yielded similar elevations in 18∶2n−6 and reduced 20∶4n−6. In contrast, lymphocytes appeared to have the reverse pattern, i.e., significantly reduced 18∶2n−6 and elevated 20∶4n−6 levels. These data suggest that atopic leukocytes may have altered essential fatty acid metabolism.
Measurement of the incorporation of orally administered arachidonic acid into tissue lipids
Authors: Kulmacz Richard J. , Sivarajan Muthumalayan , Lands William E. M.
Published: November 2006

The applicability of a stable isotope method to monitor the mixing of dietary arachidonic acid with endogenous arachidonic acid in tissue lipids was evaluated. Rats were fed octadeuterated arachidonic acid during a 20‐day period, and the entry of the dietary acid into lipid esters of various tissues was examined by gas chromatographymass spectrometric (GC‐MS) analysis of their fatty acids. The rats were maintained on a fat‐free diet from weaning until 63 days old to enhance the ratio of the dietary acid to endogenous arachidonate. Three separate forms of eicosatetraenoic acid in the tissue lipids could be distinguished by GC‐MS: octadeuterated arachidonic acid (recent dietary origin), unlabeled arachidonic acid (maternal origin) and unlabeled, 4,7,10,13‐eicosatetraenoic acid (originating from palmitoleic acid).

The total eicosatetraenoic acid in the tissue lipids contained about 90% arachidonate from recent dietary origin in lung, kidney, heart and fat, 70% in muscle and liver and 27% in brain. The n−7 isomer of eicosatetraenoic acid was estimated to make up 6% or less of the total eicosatetraenoic acid in lung, kidney, brain, muscle and heart tissue lipids, but it comprised around 15% of the total eicosatetraenoic acid in liver. The unlabeled arachidonic acid of maternal origin thus comprised only about 10% of the eicosatetraenoic acid in all tissues examined except muscle and brain, where it was 24% and 70% of the eicosatetraenoic acid, respectively.

The relative amounts of the three forms of eicosatetraenoic acid are consistent with a limited access of dietary arachidonate to the brain tissue and with a competition between the dietary n−6 isomer and the endogenous n−7 isomer for esterification in the liver. Because most muscle mass would have formed after weaning, the high proportion of maternal arachidonate in the muscle lipids suggested that maternal arachidonate may have been displaced from other tissues to muscle, from which it equilibrated slowly with dietary arachidonate acid. The combination of deuterated arachidonic acid and GC‐MS analysis thus furnished more detailed information about the composition and origin of eicosatetraenoic, acid in tissue lipid esters than that previously available from radiotracer studies or GC‐MS analyses alone.
Oxysterols: Chemical synthesis, biosynthesis and biological activities
Authors: Parish Edward J. , Nanduri Venkata B. B. , Kohl Herbert H. , Taylor Frederick R.
Published: November 2006

As a class of compounds, oxysterols have demonstrated a wide variety of biological properties. Due to the general interest in these compounds, new methods of chemical synthesis have been developed to provide them for biological investigation. The specific inhibition by oxysterols of cholesterol biosynthesis in mammalian cells has been shown to result primarily from a decrease in cellular levels of 3‐hydroxy‐3‐methylglutaryl coenzyme A (HMG‐CoA) reductase activity. Recent evidence suggests these cellular responses may be mediated by an oxysterol binding protein found in the cytosol of many lines of cultured cells. In certain instances, oxysterols have been shown to be produced in biological systems. These results support the supposition that oxysterols may regulate sterol biosynthesis at the cellular level. Included herein are the inhibitory effects of 9α, 11α‐epoxycholest‐7‐en‐3β‐ol cholest‐8‐en‐3β‐ol‐7‐one and cholest‐8‐en‐3β‐ol‐11‐one on HMG‐CoA reductase activity and their relative affinities for a cytosolic binding protein.
Sterol composition during the life cycle of the soybean and the squash
Authors: Fenner Gregory P. , Patterson Glenn W. , Koines Penelope M.
Published: November 2006

Sterol analyses were performed on soybeans and squash at intervals throughout the life cycle from seed to mature seed‐bearing plant. The sterols of the soybean (24‐methyl‐cholesterol, stigmasterol and sitosterol) increased in quantity from that in the seed in each stage examined except for a pause or decrease prior to flowering and a decrease at senescence. Individual sterols remained in the same proportion to each other and changes in content were similar in roots and shoots. In the squash a much more complicated sterol mixture was found, composed primarily of C‐7 unsaturated sterols characteristic of Cucurbitaceae. Sterol composition also increased during the life cycle except for approximately two wk in the preflowering to early flowering period. The data indicate low synthesis or high turnover of sterols (or both) in these plants in the weeks at or just prior to flowering.
Sterol composition and biosynthesis in sorghum: Importance to developmental regulation
Authors: Heupel Rick C. , Sauvaire Y. , Le Phu H. , Parish Edward J. , Nes W. David
Published: November 2006

Sterol composition and biosynthesis have been examined in seeds, germinating seeds and blades from fally matured leaves ofSorghum bicolor in various stages of development’from seedlings (seven‐day plants) to flowering (66‐day) plants. The profile of the dominant free sterols of seeds was similar to that of leaf blades; both contained cholesterol, 24α‐methylcholesterol (campesterol), 24β‐methylcholesterol (dihydrobrassicasterol), 24α‐ethylcholesterol (sitosterol) and 24α‐ethylcholesta‐5,22‐dienol (stigmasterol). Sufficient sterol intermediates were identified in the plant to indicate separate post‐cycloartenol pathways to sterolic end products. The total free sterol content of the seed (μg/seed) increased somewhat during the 20 hr germination period. However, as the plant developed (seven to 48 days), there was a logarithmic increase in the leaf blade sterol content (μg/leaf blade) which plateaued at the onset of floral differentiation (ca. day 41). Over the next 18 days (48 to 66 days—period of inflorescense development), the sterol content rapidly decreased. In the early stages of plant development, the leaf blade pentacyclic triterpenoid (PT) content was negligible. With the onset of floral differentiation, PT content increased logarithmically, reaching a plateau level that surpassed the sterol content as flowering progressed. These results imply that a critical mass of sterol is associated with sorghum for floral induction. Sterol loss from the leaves of the flowering plants presumably was compensated for by the diversion of 2,3‐oxidosqualene (SO) from sterol synthesis to PT production. Additional feeding and trapping experiments with [2‐14C]mevalonic acid, [2‐3H]cycloartenol, [24‐3H]lanosterol [4‐14C]sitosterol and [4‐14C]cholesterol fed to germinating seeds and leaves from flowering plants demonstrated that sorghum possessed a cycloartenolbased pathway; germinating seeds synthesized 24‐alkylsterols but not cholesterol, although cholesterol was identified in both dry and germinating seeds by gas chromatography‐mass spectroscopy (GC‐MS); and mature leaves synthesized cholesterol and 24α‐alkylsterols but not 24β‐methylcholesterol.
The fate of radiolabeled steroids in ovaries and eggs of the tobacco hornworm,Manduca sexta
Authors: Thompson Malcolm J. , Svoboda James A. , Feldlaufer Mark F. , Lozano Ruben
Published: November 2006

To determine the precursors and the fate of 26‐hydroxyecdysone in eggs, the fate of labeled putative ecdysteroid precursors was examined in the tobacco hornworm,Manduca sexta. Following injection of [14C]cholesterol, 22,25[14C]dideoxyecdysome or [3H]ecdysone into female pupae (day 16), only [14C]cholesterol was incorporated and metabolized. It was converted to labeled nonecdysteroid and ecdysteroid conjugates, of which the latter in ovaries and 48‐ to 64‐hr‐old eggs is mainly 26‐hydroxyecdysone 26‐phosphate (>85% in ovaries). Quantitation of the ecdysteroid conjugate by reversed‐phase high performance liquid chromatography (RP‐HPLC) showed that the levels of 26‐hydroxyecdysone 26‐phosphate were 31 μg/g of ovaries from 4‐day‐old females and 25 μg/g and 17 μg/g of 48‐ to 64‐hr‐old and 72‐ to 88‐hr‐old eggs, respectively. The RP‐HPLC of the conjugate fraction of 48‐ to 64‐hr‐old eggs showed an additional peak of radioactive material eluting about three min before the 26‐hydroxyecdysone 26‐phosphate. The quantity of this material increased in the 72‐to 88‐hr‐old eggs, though it was not detected in the analyses of the conjugate fraction from ovaries. Additional peaks of radioactive material eluting before the 26‐hydroxyecdysone 26‐phosphate peak were observed in the chromatogram of the conjugates of 72‐ to 88‐hr‐old eggs. These radioactive materials need to be identified to determine the ultimate fate of ecdysteroids in the developing embryos of the tobacco hornworm. No radioactive free ecdysteroids were detected in either egg age group.
Hydroxymethylglutaryl‐CoA reductase, a key enzyme in phytosterol synthesis?
Authors: Bach Thomas J.
Published: November 2006

Hydroxymethylglutaryl‐CoA reductase (HMGR) regulates the synthesis of mevalonic acid (MVA), the precursor of the myriad of isoprenoid compounds functional in plant cells, with phytosterols representing one class of major importance. Recently, it has shown possible to solubilize and purify the membrane‐bound enzyme from a heavy membrane fraction (P 16,000×g) isolated from a cell‐free homogenate of etiolated radish seedlings. What is presently known about the molecular and kinetic properties of radish HMGR is reported.

Mevinolin, a highly specific competitive inhibitor of HMGR, has been valuable as a research tool in studying the regulatory role of HMGR activity for the growth and development of intact seedlings and cell cultures. The results obtained indicate a primary effect of mevinolin on phytosterol accumulation, whereas other endproducts of the multibranched isoprenoid pathway, such as ubiquinone in the mitochondria or chlorophylls and carotenoids in the plastids, are less or not at all affected. This and other data can be interpreted to mean that the organelles are autonomous in their capacity to synthesize MVA. Since the mevinolin‐induced drop in free sterol accumulation is paralleled by significant plant growth retardation, a rate‐limiting role of HMGR activity for phytosterol synthesis and normal development of plants is suggested.
An essential fungal growth factor derived from ergosterol: A new end product of sterol biosynthesis in fungi?
Authors: Parks Leo W. , Rodriguez Russell J. , Low Christopher
Published: November 2006

Concentrations of ergosterol as low as 1.2 mM are effective in satisfying the essential high specificity microrequirement for C5,6 unsaturated sterol in yeast. In a sterol auxotroph supplemented with saturated sterol (cholestanol), aqueous extracts of yeast provide a growth factor that eliminates the ergosterol microrequirement. The factor is easily differentiated from ergosterol by solubility, thermostability, and thin layer and liquid chromatography and is functional at levels equivalent to those of vitamins, hormones and pheromones.
Sterol analysis of the inner and outer mitochondrial membranes in yeast
Authors: Bottema C. K. , Parks L. W.
Published: November 2006

The membranes of yeast mitochondria were separated and analyzed for lipid content. The sterolto‐phospholipid molar ratio was found to be very similar between the inner and outer membranes (1∶30). These observed ratios could be substantially altered by using a crude mitochondrial pellet contaminated with a “floating lipid layer”. In this case, the sterol‐to‐phospholipid molar ratios were 1∶8 to 1∶26 for the outer and inner mitochondrial membranes, respectively.
Influence of lecithin on the chromatography of steroidal glucosiduronates in chloroform/formamide
Authors: Mattox Vernon R. , Litwiller Robert D.
Published: November 2006

The interaction between lecithin and steroidal glucosiduronates was investigated by use of partition chromatography in chloroform/formamide and infrared spectroscopy. It was observed that lecithin increases the solubility of both glucosiduronic acids and esters in chloroform and concluded that this phenomenon occurs because of the formation of hydrogen bonds between the phosphodiester group of lecithin and hydroxyl groups of the steroid conjugates.
Cholesteryl ester hydrolase activity in human symptomatic atherosclerosis
Authors: Yatsu F. M. , Hagemenas F. C. , Manaugh L. C. , Galambos T.
Published: November 2006

Acid cholesteryl ester hydrolase (CEH) activity was assayed in mononuclear cells of patients with symptomatic atherosclerosis (transient ischemic attacks, TIA) and in age‐matched controls showing no evidence of atherosclerosis. The acid CEH level of TIA patients was significantly lower than that of controls (1074±128 vs 2113±255 pmol/mg P/hr, mean±SE). Neither mononuclear cell nor plasma cholesterol and cholesteryl ester concentrations differed significantly between atherosclerotic and control groups. TIA women had lower mononuclear cell concentrations of free sholesterol than men.
Effect of epinephrine and dibutyryl cyclic AMP on Δ5‐desaturation activity of rat liver microsomes
Authors: de Gomez Dumm I. N. T. , de Alaniz M. J. T. , Brenner R. R.
Published: November 2006

The effect of epinephrine and dibutyryl cyclic AMP on the oxidative desaturation of [1‐14C]‐eicosatrienoic acid to arachidonic acid of rat liver microsomes has been studied. Epinephrine, at a dose of 1 mg/kg/body weight, produced a significant decrease on Δ5‐desaturation activity 3 hr after the injection. This effect was maintained up to 12 hr and reached the control values 48 hr after the hormone administration. Dibutyryl cyclic AMP treatment for 24 hr (5 mg/8 hr/100 g body weight) also produced a significant decrease of the conversion of eicosatrienoic acid to arachidonic acid in rat liver microsomes. The effect of epinephrine on Δ5‐desaturation activity was postulated to be evoked through an increase of the intracellular concentration of cyclic AMP.
Esterified lipids of the freshwater dinoflagellatePeridinium lomnickii
Authors: Cranwell P. A. , Robinson N. , Eglinton G.
Published: November 2006

Steryl esters, phytyl esters and triacylglycerols of a naturally occurring freshwater dinoflagellate,Peridinium lomnickii, were identified using capillary gas chromatography‐mass spectrometry (GC‐MS). Steryl esters differing in degree of unsaturation were separated, prior to analysis, by argentation thin layer chromatography. 5α(H)‐Cholestanol was more dominant, relative to 4α‐methylstanols, in steryl esters than in the free sterols, but the same sterol moieties occurred in both fractions. Monoenoic fatty acids were enriched in the steryl esters relative to the free fatty acids. Major acyl groups in steryl esters were 16∶0 or 20∶1, with smaller amounts of 14∶0 and 18∶1. In triacylglycerols the acyl moieties were 14∶0, 16∶0, 18∶1, 16∶1 and 12∶0, in order of decreasing abundance. Phytyl esters, previously inferred to occur in a marine dinoflagellate only by analysis of transesterified products, were identified by GC‐MS comparison with authentic compounds. Direct analysis of these esterified lipids has not been reported for freshwater phytoplankton. The 4α‐methylstanyl esters, 5α(H)‐cholestan‐3β‐yl esters and phytyl esters occurring inP. lomnickii are further features in common with marine dinoflagellates, additional to the 4α‐methylsterols reported previously.