bluuebunny/crossref_metadata_2025 huggingface dataset:
Modulation of platelet thromboxane and malonaldehyde by dietary vitamin E and linoleate
Authors: Hamelin Suzanne S. ‐J. , Chan Alvin C.
Published: December 2006

Thromboxane (TXB2) and malonaldehyde (MDA) production by thrombin‐stimulated washed platelet were evaluated in rats fed 6 combinations of dietary vitamin E (0, 100, 1000 ppm) and linoleate (6.5 and 17.0 en%) for 23 weeks. The molar ratio of MDA:TXB2 was consistently near 3 in all groups studied. In animals receiving the lower linoleate diets, TXB2 and MDA synthesis were inversely related to the dietary vitamin E concentrations and the levels of MDA and TXB2 were positively correlated (r=0.99) with decreasing vitamin E in the diet. High dietary linoleate (17.0 en%), independent of vitamin E status, reduces TXB2 and MDA synthesis. The importance of dietary antioxidant on platelet prostanoid synthesis is discussed.
Temperature effects on in vitro lipid accumulation in asexual embryos ofTheobroma cacao L.
Authors: Wright Daniel C. , Janick Jules , Hasegawa Paul M.
Published: December 2006

Asexual embryos of cacao were grown for 40–50 days in a modified Murashige and Skoog liquid medium with sucrose concentration increased stepwise from 3 to 27% at temperatures of 10, 17, 20, 23, 26, 29, 32 or 35 C. Temperature influenced overall embryo growth as well as lipid accumulation and composition. Maximum growth occurred at 29 C, whereas maximum lipid and fatty acid accumulation occurred at 26 C. The proportion of individual fatty acids as total fatty acids accumulated per asexual embryo was constant at each temperature but varied with temperature from 10 to 35 C. The fatty acid composition of asexual embryos grown at 26 C was the most similar to that of cocoa butter, the lipid from mature zygotic embryos produced in vivo.
Elevated levels of arachidonic acid in fish from northern Australian coastal waters
Authors: Sinclair Andrew J. , O'Dea Kerin , Naughton Joan M.
Published: December 2006

The fatty acid composition of 10 species of fish caught off the northwest coast of Australia (latitude 17°S) was examined. All species contained high levels of ω6 fatty acids (9.6–23.1% of total fatty acids) with arachidonic acid being the major ω6 fatty acid (5.9–14.8% of fatty acids). Docosatetraenoic and docosapentaenoic acids of the ω6 series accounted for 3–8% of the total fatty acids. The ratio of ω6 to ω3 fatty acids in these fish varied from 0.38 to 0.93, compared with an average ratio of 0.16 for fish from the northern hemisphere (latitude >30°N). The present data and figures from the literature indicate that the marine food chain in the southern hemisphere contains significant quantities of ω6 fatty acids.
A simple synthesis of 5,8,11‐eicosatrienoic acid
Authors: Parish Harlie A. , Gilliom Richard D. , Purcell William P.
Published: December 2006

A straighforward synthesis of Z,Z,Z‐5,8,11‐eicosatrienoic acid is described that gives a pure product without chromatography. The C20‐polyacetylenic acid is purified by recrystallization and then reduced by a Lindlar catalyst in an aprotic solvent with a trace quantity of quinoline.
Hydroxylation of secondary bile acids in the perfused prairie dog liver
Authors: Cohen Bertram I. , Singhal Anil K. , Mongelli Joseph , Rothschild Marcus A. , McSherry Charles K. , Mosbach Erwin H.
Published: December 2006

Taurolithocholic acid and deoxycholic acid were perfused into isolated prairie dog livers. Taurolithocholic acid was 7α‐hydroxylated to form taurochenodeoxycholic acid, whereas deoxycholic acid was conjugated and 7α‐hydroxylated to form taurocholic acid. The low concentrations of secondary bile acids observed in prairie dog bile are due, at least in part, to active bile acid 7α‐hydroxylase(s) in the liver of these animals.
Tissue culture of cocoa bean (Theobroma cacao L.): Incorporation of fatty acids into lipids of cultured cells
Authors: Tsai C. H. , Kinsella J. E.
Published: December 2006

Suspension cell cultures of cocoa bean rapidly incorporated palmitic, stearic, oleic and linoleic acids into cellular lipids. Thus, 75 and 20% of [1‐14C] palmitic acid was incorporated into polar lipids and triglycerides, respectively, after 48 hr. When [1‐14C] oleic and [1‐14C] linoleic acid were added separately, polar lipids consistently contained most of the radioactive fatty acids. Ca. 60% of the stearic acid accumulated as unesterified fatty acid in the cells. Palmitic and stearic acid were not desaturated, but oleic acid and linoleic acid were further desaturated. The kinetics of conversion of oleic acid and linoleic acid suggested a sequential desaturation pathway of 18∶1→18∶2→18∶3 in cocoa bean cell suspensions.
Identification of 27‐nor‐(24R)‐24‐methylcholesta‐5,22‐dien‐3β‐ol and brassicasterol as the major sterols of the marine dinoflagellateGymnodinium simplex
Authors: Goad L. John , Withers Nancy
Published: December 2006

The major 4α‐monomethyl sterol of the dinoflagellateGymnodinium simplex was identified as (24S)‐4α,24‐ dimethylcholestan‐3β‐ol. The major 4‐demethyl sterols were characterized as (24R)‐24‐methylcholesta‐5,22‐dien‐3β‐ol (brassicasterol) and 27‐nor‐(24R)‐24‐methylcholesta‐5,22‐dien‐3β‐ol. The latter sterol has the opposite configuration at C‐24 to that assigned to occelasterol, which has the same basic structure and has previously been reported as a constituent of the sterols of a marine worm. 24‐Nor‐cholesta‐5,22‐dien‐3β‐ol was also identified along with several other trace sterols. The co‐occurrence of 27‐nor‐(24R)‐cholesta‐5,22‐dien‐3β‐ol together with 24‐nor‐cholesta‐5,22‐dien‐3β‐ol and brassicasterol provides new evidence for the biosynthetic origins of the two former nor‐sterols. It is suggested that they may be produced de novo by a route involving nor‐isoprenoid pyrophosphates and nor‐squalene as intermediates, rather than as bacterial degradation products of brassicasterol (or related sterols) as previously suggested in the literature.
Effect of inhibitors on ω‐and (ω‐1)‐hydroxylation of lauric acid by frog liver microsomes
Authors: Miura Yoshiro
Published: December 2006

To investigate the involvement of different cytochrome P‐450 monooxygenases in fatty acid hydroxylation in frog liver microsomes, the effect of various inhibitors of cytochrome P‐450 monooxygenases on the ω‐ and (ω‐1)‐hydroxylation of laurate was examined. The ω/ω‐1‐hydroxylation ratios were changed significantly by various levels of carbon monooxide (CO) inhibition; the formation of ω‐hydroxylaurate was more sharply inhibited by various levels of CO than was the formation of (ω‐1)‐hydroxylaurate. On the contrary, metyrapone inhibited only the formation of (ω‐1)‐hydroxylaurate and stimulated the formation of ω‐hydroxylaurate. 7,8‐Benzoflavone as well as CO was more inhibitory to the ω‐hydroxylation of laurate. At low concentrations of KCN (0.2 and 0.1 mM), the (ω‐1)‐hydroxylase activity was stimulated, but both the ω‐ and (ω‐1)‐hydroxylase activities were inhibited at the higher concentrations (5–10 mM). The effect of drugs and hydroxylaurate isomers on the ω‐ and (ω‐1)‐hydroxylation was also examined. Aminopyrine showed a stimulative effect on ω‐hydroxylase activity and no effect on the (ω‐1)‐hydroxylase activity, whilep‐nitroanisole inhibited the (ω‐1)‐hydroxylase activity and showed almost no effect on the ω‐hydroxylase activity. 12‐Hydroxylaurate inhibited both the ω‐ and (ω‐1)‐hydroxylase activities, but the ω‐hydroxylase activity was inhibited to a much greater extent. 11‐Hydroxylaurate had no effect on either hydroxylation. These findings strongly support the hypothesis that different cytochrome P‐450 species are involved in the hepatic microsomal hydroxylation of laurate at ω‐ and (ω‐1)‐positions in the frog.
Source of lung surfactant phospholipids: Comparison of palmitate and acetate as precursors
Authors: Sato Tadahiro , Akino Toyoaki
Published: December 2006

The phospholipids and the fatty acid compositions of major phospholipids in rat lung parenchyma, microsomes, lamellar bodies and alveolar wash were quantified. Adult rats were injected simultaneously with [3H] palmitate and [14C] acetate into the femoral vein. The appearance of labeled phosphatidylcholine (PC), disaturated phosphatidylcholine (DSPC) and phosphatidylglycerol (PG) in each lung fraction was measured during short periods of time (5 min to 2 hr) after isotope administration. Relatively more PC, DSPC and PG labeled with acetate radioactivity in lung microsomes entered lamellar body and alveolar wash fractions than those labeled with palmitate radioactivity. However, there was no difference between palmitate and acetate labeled phospholipids in the transport from microsomes to lamellar bodies by phospholipid exchange proteins. On the other hand, prior injection of colchicine resulted in decrease in the transport of PC from microsomes to alveolar space to a relatively greater extent in the acetate radioactivity than in the palmitate radioactivity.
Stimulation of hepatic squalene and triglyceride synthesis by dimethylsulfoxide, in vitro
Authors: Bell Frank P. , Hubert Edna V.
Published: December 2006

The incorporation of [14C] mevalonate and [14C] acetate into squalene by rat liver slices was increased over 7‐fold by the presence of 5% dimethylsulfoxide (DMSO) in the incubation medium. The stimulation of squalene synthesis was dose‐related over the concentration range of 1–5% DMSO and did not affect the incorporation of [14C] mevalonate, into the C27‐sterol fraction (cholesterol) but did increase (about 50%) incorporation into C30‐sterol (lanosterol) at a level, of 5% DMSO. The stimulation of squalene synthesis was observed under both anaerobic (N2 atmosphere) and aerobic (ambient air or 95% O2/5% CO2) conditions and may represent a direct effect of DMSO on squalene synthetase. At a level of 5%, DMSO also stimulated 7‐fold the incorporation of [14C] acetate into triglycerides by liver slices; this occurred without changes in incorporation into the phospholipid or free fatty acid fractions. The disproportionate increase in lipid labeling from [14C] acetate suggests that the effects of DMSO are not simply a matter of increasing [14C] acetate entry into the tissue.
Effects of cereals and culture filtrate ofTrichoderma viride on lipid metabolism of swine
Authors: Qureshi Asaf A. , Burger Warren C. , Elson Charles E. , Benevenga Norlin J.
Published: December 2006

Swine were fed corn‐or barley‐based diets with, or without, culture filtrate (CF) ofTrichoderma viride for 21 days. Weight gains were nonsignificantly but slightly increased by CF. The activities of β‐hydroxy‐β‐methylglutaryl coenzyme A (HMG‐CoA) reductase, cholesterol 7α‐hydroxylase, acetyl‐CoA carboxylase (ACX), fatty acid synthetase (FAS) and other lipogenic enzymes in several tissues were determined. Significant decreases in the activities of HMG‐CoA reductase and cholesterol 7α‐hydroxylase in all tissues of swine fed the CF‐diets were observed. The major site for the regulation of cholesterol biosynthesis was adipose tissue followed by the intestine, liver, lung and muscle in order of activity The concentrations of cholesterol in serum and muscle were decreased 27% and 23%, respectively, by CF. ACX and FAS activities increased ca. 2‐fold when CF was fed with either of the cereal‐based diets. The major sites for fatty acid synthesis was the adipose tissue and, to a lesser extent, the liver. Very low rates of synthesis were detected in intestine, lung and muscle. Similar distributions of activities were found for related lipogenic enzymes.
Lipid profiles of taste and non‐taste epithelial tissues from steer tongues
Authors: Rabinowitz Joseph L. , Brand Joseph G. , Bayley Douglas L.
Published: December 2006

Some hypotheses on taste reception have implicated lipids of taste cells as major receptor constitutents. This study reports detailed lipid profiles of the taste bud‐containing epidermis from circumvallate papillae and fungiform papillae as well as profiles from two non‐taste bud tissues: circumvallate papillae dermis and epidermis from the lateral posterior of the tongue. Differences in levels of triglycerides and phosphatidylcholines were observed but these were not directly related to the presence of taste buds. At this level of analysis, it is evident that there are no unusual distributions of phospholipid classes in the taste bud epidermis when compared with the non‐taste bud lingual epidermis.
Partial purification and characterization of a Ca2+‐stimulated lipoxygenase from soybean seeds
Authors: Dreesen Thomas D. , Dickens Martha , Koch Robert B.
Published: December 2006

A highly purified Ca2+‐stimulated lipoxygenase was isolated from the Hill variety of soybean seeds. Separation of Ca2+‐stimulated lipoxygenase from lipoxygenase active in the absence of Ca2+ (lipoxygenase‐1) was readily obtained using a DEAE‐cellulose column. Sample size applied to the ion exchange column was found to be critical. Both enzymes were bound to the column, although some highly active Ca2+‐stimulated lipoxygenase eluted with buffer in the presence of bound lipoxygenase‐1. Ca2+‐stimulated lipoxygenase bound to DAAE‐cellulose required the use of a NaCl gradient for elution. Ca2+‐stimulated lipoxygenase showed an apparent isoelectric point at pH 5.90 and optimum activity at pH 7.5 and at 1.1 mM calcium. Lipoxygenase‐1 was inhibited over 95% in the presence of 60 μM methyl mercuric chloride, while Ca2+‐stimulated lipoxygenase showed a maximum of only 20% inhibition under the same conditions.
Temperature sensitivity of cholesteryl ester hydrolases in the rat testis
Authors: Durham Lucian A. , Grogan W. McLean
Published: December 2006

Cholesteryl ester hydrolase (CEH) (EC 3.1.1.13) activity was assayed in the 104,000×g supernatant (S104) of rat and mouse testes and livers at various temperatures between 27 C and 44 C. The CEH activity in the testis dropped from 44 pmol [4‐14C] cholesteryl oleate hydrolyzed/hr/mg protein to 14 pmol hydrolyzed/hr/mg protein (a 68% decrease) between testicular and abdominal temperatures (32 C and 37 C, respectively) in the rat. This decrease in activity is essentially a reversible phenomenon. CEH from the testis S104 was stabilized in 10 mM EDTA and was purified by HPLC size exclusion. These steps did not alter the temperature effect previously noted. The temperature effect on the testicular CEH was demonstrated in vivo by assaying the enzyme following unilateral cryptorchidism. The HPLC purification yielded 3 peaks of CEH activity from the testicular S104. The 28,000 MW peak was found to be temperature insensitive while the 70,000 and 420,000 MW peaks were temperature labile. The liver CEH of both species remained relatively constant over the range 32—37 C. CEH is a potential regulator of both steroidogenesis and membrane composition in the testis and its temperature lability may suggest a unique regulatory mechanism responsible for impaired spermatogenesis seen with elevated testicular temperatures.
Distribution of methylene and nonmethylene‐interrupted dienoic fatty acids in polar lipids and triacylglycerols of selected tissues of the hardshell clam (Mercenaria mercenaria)
Authors: Klingensmith J. Scott
Published: December 2006

Fatty acid profiles of polar lipids and triacylglycerols were determined for 6 tissues of the hardshell clam (Mercenaria mercenaria), namely, mantle, gill, mouth, foot, digestive tract/gonadal tissue and adductor muscle. The largest concentrations of nonmethylene‐interrupted dienoic (NMID) fatty acids were found in the gill, mantle, and foot. Structural analyses were undertaken to determine the double bond configurations of the various NMID isomers. The major 22C NMID species were Δ7,13‐ and Δ7,15‐docosadienoic acid. The major 20C NMID species were Δ7,11‐ and Δ7,13‐eicosadienoic acid and Δ5,11‐eicosadienoic acid.
A high‐yield saponification of galactosylceramide I3‐sulfate
Authors: Koshy K. M. , Boggs J. M.
Published: December 2006

A method for the deacylation of galactosylceramide I3‐sulphate using aqueous methanolic KOH is described. The combination of a relatively low concentration of the alkali (0.3 M) and a moderate reaction temperature (reflux point of 90% methanol) results in the formation of galactosylsphingosine I3‐sulphate in consistently high yields (61%) with a minimum of side reactions. The product was purified by column chromatography and its identity established by thin layer chromatography, infrared spectroscopy, determination of galactose content and organic sulphate assay using established methods or their modifications.
The absorption and transport of dietary cholesterol in the presence of peanut oil or randomized peanut oil
Authors: Tso Patrick , Pinkston Gene , Klurfeld David M. , Kritchevsky David
Published: December 2006

Peanut oil has been shown to be unexpectedly atherogenic for cholesterol‐fed rats, rabbits and rhesus monkeys. However, randomization (rearrangement of fatty acids to random distribution) of peanut oil significantly reduced its atherogenicity for rabbits and monkeys. This study was conducted to investigate whether the absorption and transport of dietary cholesterol was altered in the presence of peanut oil or randomized peanut oil, thereby accounting for the difference in the atherogenicity of the two diets. Intestinal lymph fistula rats were infused intraduodenally with a lipid emulsion at a rate of 3 ml/hr. The lipid emulsion contained either peanut oil (control) or randomized peanut oil (experimental) (10 mM),14C‐cholesterol (1.3 mM) and sodium taurocholate (19 mM) in phosphate‐buffered saline, pH 6.4. Lymph triglyceride, cholesterol and phospholipid outputs were similar in both groups of rats during fasting and subsequently during lipid infusion. Comparable recovery of14C‐cholesterol from the intestinal lumen and the intestinal mucosa of the control and the experimental rats showed that the absorotion and transport of dietary cholesterol were similar in both groups of rats. Analyses of thefatty acid of both lymph and intestinal mucosal lipid again failed to reveal a difference between the 2 groups of rats. It is concluded that the difference in the atherogenicity between the peanut oil and the randomized peanut oil is probably caused by events subsequent to the release of cholesterol containing chylomicrons and very low density lipoproteins by the small intestinal epithelial cells.
The role of calcium in the regulation of prostacyclin synthesis by porcine aortic endothelial cells
Authors: Whorton A. R. , Willis C. E. , Kent R. S. , Young S. L.
Published: December 2006

Both bradykinin (EC50=8 ng/ml) and the ionophore A23187 (EC50=3×10−7 M) potently stimulated arachidonate release and prostaglandin synthesis in porcine aortic endothelial cells. The response to each was completely dependent on extracellular Ca2+ (EC50=3×10−7 M); no role for intracellular Ca2+ was noted. The rapid Ca2+ influx prompted by either activator was consistent with the time course for arachidonate release. Whereas the arachidonate released in response to bradykinin was trasient, that released in response to A23187 was more prolonged, and paralleled a continued influx of Ca2+. Ca2+ entry elicited by bradykinin was mediated by channels which could not be blocked by verapamil. When Mn2+ was substituted for Ca2+, no stimulation of prostacyclin synthesis was seen in response to A23187; however, the bradykinin response was unaffected. The mechanism of these effects was studied using doses of bradykinin or A23187 which resulted in increases in Ca2+ influx and prostacyclin synthesis of similar magnitude for each agonist. Under these conditions, trifluoperazine blocked elevated prostacyclin synthesis (ID50=5–6×10−6 M for each agonist). Trifluoperazine sulfoxide, however, was much less active. Pimozide inhibited bradykinin‐stimulated prostacyclin synthesis at low doses (ID50=3×10−6 M). Trifluoperazine was much less effective against high doses of A23187 (4×10−6 M). These data suggest that arachidonate release and prostacyclin synthesis are dependent on influx of extracellular calcium and subsequent activation of a Ca2+‐dependent phospholipase by a calmodulin‐mediated mechanism.
A unique lipid pattern associated with the gall bladder bile of the chick embryo
Authors: Noble R. C. , Connor K.
Published: December 2006

A study has been made of the lipid and fatty acid composition of the gall bladder bile of the chick embryo during the last week of incubation. The lipids and their fatty acid composition showed a unique pattern when compared to other animal species. Of the total lipid present, phospholipid accounted for less than half, and there were substantial proportions of both cholesteryl ester and triglyceride. In the cholesteryl ester, the proportion of which increased significantly over the last week of incubation, there was a very high level of oleic acid. The phospholipid contained a high level of arachidonic acid. The results are discussed in relation to observations on the biliary lipids of other animal species and the major features of the lipid metabolism of the chick embryo during the last week of incubation.
A nuclear magnetic resonance spectroscopic investigation of the headgroup motions of lysophospholipids in bilayers
Authors: Wu W. , Stephenson' F. A. , Mason J. T. , Huang C.
Published: December 2006

Fully hydrated lysophospholipids in both the gel and the liquid crystalline states have been shown to exhibit negative phosphorus chemical shift anisotropies (Δσ) by31P nuclear magnetic resonance (NMR). The magnitude of Δσ for monoacyl lysophospholipids is found to be smaller than that of the corresponding diacyl phosphospholipids in bilayers by about a factor of two. We present evidence to suggest that the reduction in Δσ can be attributed primarily to an additional motional averaging of the lysophospholipid headgroup, and the additional motion can best be explained by rapid rotational motions of the headgroup about the C(1)‐C(2) glycerol bond.
Australian fish—An excellent source of both arachidonic acid and ω‐3 polyunsaturated fatty acids
Authors: Gibson R. A.
Published: December 2006

The fatty acid methyl esters obtained by the esterification of total lipids extracted from 24 species of fin fish and 4 species of invertebrates caught in the rivers and coastal waters of southern Australia were analyzed by gas chromatography. The lipids of most species contained significant levels of arachidonic acid (0.7–15.8%) as well as the more common marine polyunsaturate, eicosapentaenoic acid (0.7–15.9%). The major ω6 fatty acid present in most species was 20∶4; however, other fatty acids of this series, including 18∶2, 22∶4 and 22∶5, were present. The level of total ω6 fatty acids ranged from 3.9 to 22.3% of the total lipid. In general, the level of total ω3 polyunsaturates was higher than the total ω6 fatty acids with levels of ω3 fatty acids ranging from 9.6 to 48.2%. Only 2 fish (barramundi and gurnard perch) had ω6/ω3 ratios greater than 1.0. Most of the Australian species examined contained low levels of fat (0.5–7.8% of fresh weight). Two species examined, callop (freshwater) and blue groper (marine) contained sufficient quantities of both fat (7.7 and 7.8%) and arachidonic acid (4.8 and 9.3%) to warrant consideration for commercial exploitation.
Acyl group distributions in tissue lipids of rats fed evening primrose oil (λ‐linolenic plus linoleic acid) or soybean oil (α‐linolenic plus linoleic acid)
Authors: Høy C. ‐E. , Hølmer G. , Kaur N. , Byrjalsen I. , Kirstein D.
Published: December 2006

Three groups of rats were fed diets with either 10 weight percent (wt%) of evening primrose oil, safflower oil or soybean oil for 11 weeks. Diets contained 7.1 wt% linoleic acid +0.8 wt% γ‐linolenic acid, 7.6 wt% linoleic acid, or 5.3 wt% linoleic acid +0.7 wt% α‐linolenic acid, respectively. In liver mitochondria as well as in heart, dietary γ‐linolenic acid did not affect the fatty acid profiles of phosphatidylcholnes (PC), phosphatidylethanolamines (PE) or cardiolipins (CL), whereas dietary α‐linolenic acid caused an increased formation of (n−3) polyunsaturated fatty acids (PUFA). The liver Δ6− and Δ5‐desaturase activities determined in vitro were not affected by the dietary fats. In brain PE, which are rich in C22− and C20‐(n−3) PUFA, as well as in testes PC and PE, which are rich in (n−6) PUFA, no effects were found from a partial replacement of dietary linoleic acid with γ‐linolenic acid or α‐linolenic acid. In kidney PC, PE, phosphatidylinositol (PI) and CL, 20∶3(n−6) was moderately elevated to ca. 1% following intake of γ‐linolenic acid, whereas partial replacement of linoleic acid with α‐linolenic acid was followed by increased deposition of 22∶6(n−3) in PC and PE of testes and kidney. Thus, no general effect of evening primrose oil on the content of (n−6) PUFA in rat tissue phospholipids was observed, wheras a significant incorporation of γ‐linolenic acid into liver and adipose tissue triglycerides was found.
Oleic acid transfer from microsomes to egg lecithin liposomes: Participation of fatty acid binding protein
Authors: Catala Angel , Avanzati Beatriz
Published: December 2006

Oleic acid transfer from microsomes or mitochondria to egg lecithin liposomes was stimulated by fatty acid binding protein. By gel filtration, it could be demonstrated that this protein incorporates oleic acid into liposomes. Fatty acid binding protein transfer activity was higher using microsomes rather than mitochondria, which suggests a selective interaction with different kinds of membranes. Transfer of oleic acid by this soluble protein is greater than that of stearic acid. The results indicate that fatty acid binding protein may participate in the intracellular transport of fatty acids.
1‐O‐alkyl‐linked phosphoglycerides of human platelets: Distribution of arachidonate and other acyl residues in the ether‐linked and diacyl species
Authors: Mueller Howard W. , Purdon A. David , Smith J. Bryan , Wykle Robert L.
Published: December 2006

In this study, the 1‐O‐alkyl‐2‐acyl‐sn‐glycero‐3‐phosphocholine content of human platelets was determined. The distribution of arachidonate among the 1,2‐diacyl, 1‐O‐alkyl‐2‐acyl, and 1‐O‐alk‐l′‐enyl‐2‐acyl classes of choline‐ and ethanolamine‐containing phosphoglycerides was also assessed. The major platelet phospholipids were choline‐containing phosphoglycerides (38%), ethanolamine‐containing phosphoglycerides (25%) and sphingomyelin (18%), with smaller amounts of phosphatidylserine (11%) and phosphatidylinositol (4%). In addition to the diacyl class, the choline‐linked fraction was found to contain both 1‐O‐alkyl‐2‐acyl (10%) and 1‐O‐alk‐l′‐enyl‐2‐acyl (9%) species. The ethanolamine‐linked fraction, on the other hand, had an elevated level of the 1‐O‐alk‐l′‐enyl‐2‐acyl (60%) species and a small amount of the 1‐O‐alkyl‐2‐acyl component (4%). The major fatty acyl residues found in all classes of the choline and ethanolamine phospholipids were 16∶0, 18∶0, (Δ9), 18∶2(n−6) and 20∶4(n−6). The 1‐O‐alk‐l and 1‐O‐alk‐l′‐enyl fraction of the ethanolamine‐linked phospholipids also contained substantial amounts of 22∶4(n−6), 22∶5(n−3) and 22∶6(n−3) acyl chains. Arachidonate comprised 44% of the acyl residues in thesn‐2 position of 1‐O‐alkyl‐2‐acyl‐sn‐glycero‐3‐phosphocholine. Corresponding values for the diacyl and 1‐O‐alk‐l′‐enyl‐2‐acyl species were 23% and 25%, respectively, based on all 20∶4(n−6) being linked to thesn‐2 position of all classes. In the ethanolamine‐linked phosphoglycerides, arachidonate constituted 60%, 20% and 68% of the acyl groups in thesn‐2 position of the 1,2‐diacyl, 1‐O‐alkyl‐2‐acyl and 1‐O‐alk‐l′‐enyl‐2‐acyl classes, respectively. The content of 1‐O‐alkyl‐2‐acyl‐sn‐glycero‐3‐phosphocholine appears sufficient to support the synthesis of platelet activating factor by a deacylation‐reacylation pathway in platelets. Our findings also demonstrate that human platelets contain a significant amount of 1‐O‐alkyl‐2‐arachidonyl‐sn‐glycero‐3‐phosphocholine that could possibly serve as a precursor of both platelet activating factor and bioactive arachidonate metabolites.
A comparison of the positional distribution of fatty acids in milk triglycerides of the extant monotremes platypus (Ornithorhynchus anatinus) and echidna (Tachyglossus aculeatus)
Authors: Parodi Peter W. , Griffiths Mervyn
Published: December 2006

Milk triglycerides from the platypus were subjected to fatty acid and stereospecific analysis to determine the positional distribution of fatty acids in the triglycerides. Of the major fatty acids, 12∶0 was preferentially esterified at thesn‐3 position, 14∶0 and 16∶0 were selectively associated with thesn‐2 position, and 18∶0 was located predominantly at thesn‐1 position. The unsaturated fatty acids, 14∶1, 16∶1, 18∶1, 18∶2 and 18∶3, were preferentially esterified at thesn‐3 position. The fatty acid distribution pattern of the platypus, a monotreme, is similar to that of marsupials and eutherians but is in contrast to the only other extant monotreme, the echidna.
Biphasic action of platelet‐activating factor on isolated guinea‐pig ileum
Authors: Tokumura A. , Harada K. , Fukuzawa K. , Tsukatani H.
Published: December 2006

1‐0‐Hexadecyl‐2‐0‐acetyl‐sn‐glycero‐3‐phosphocholine (platelet‐activating factor) at 10−10‐10−9 M induced slow contraction of isolated guinea‐pig ilcal muscles and the contraction persisted for a long time. At a higher concentration of 10−7 M, this phospholipid induced more rapid, but not greater, contraction. At higher concentrations (10−6‐10−5 M), this phospholipid induced a biphasic response: rapid contraction followed by relaxation. At high concentrations, this compound inhibited acetylcholine‐induced contractions. The stimulatory effect of this phospholipid was ca. 300 times that of 1‐palmitoyl‐2‐0‐acetyl‐sn‐glycero‐3‐phosphocholine, while its inhibitory potency on induced contraction was similar to those of 1‐palmitoyl‐2‐0‐acetyl‐sn‐glycero‐3‐phosphocholine and its lyso derivative. It was suggested that the differences in effects on contraction of different concentrations of 1‐0‐hexadecyl‐ and 1‐palmitoyl‐2‐0‐acetyl‐sn‐glycero‐3‐phosphocholine were due to the dual effects of these compounds on the ileum: a strong stimulatory effect and a moderate inhibitory effect on contraction.
Effect of chlorpromazine on rat arterial lipid synthesis, in vitro
Authors: Bell Frank P. , Hubert Edna V.
Published: December 2006

The effect of chlorpromazine, a major tranquilizer, on arterial lipid metabolism was studied in vitro in rat aortas incubated with [14C] acetate and [14C] mevalonate as lipid precursors. Chlorpromazine at a level of 0.25 mM in the incubation medium significantly reduced the incorporation of [14C] acetate into free fatty acids (p<0.01) and total phospholipids (p<0.001) but not triglycerides. Chlorpromazine also altered the pattern of arterial phospholipids synthesized from [14C] acetate by significantly increasing the relative proportion of phosphatidylinositol plus phosphatidylserine (p<0.02) and reducing the relative proportion of sphingomyelin (p<0.001). [14C] Acetate incorporation into the combined fractions of steryl esters plus hydrocarbons and sterols plus diglycerides was also significantly reduced (p<0.001) by 0.25 mM chlorpromazine. Studies with [14C] mevalonate showed that chlorpromazine is also an inhibitor of sterol biosynthesis in arterial tissues as evidenced by 35–40% reductions (p<0.05) in the formation of14C‐labeled squalene and C27 sterols.
The effects of phosphate on the biosynthesis of cholesterol in rat liver homogenates
Authors: Hotta S. Steven
Published: December 2006

The biosyntheses of cholesterol from acetate and mevalonate were determined in rat liver homogenates that were prepared and incubated in buffers containing varying concentrations of phosphate. Relatively little acetate or mevalonate was incorporated into cholesterol in the absence of added phosphate. When phosphate was added, there was an increase in incorporation of both substrates. The addition of phosphate resulted in an increase in the incorporation of mevalonate to a maximum, whereas phosphate appeared to increase the incorporation of acetate at low phosphate levels and decrease the incorporation at higher phosphate levels. The results appear to be consistent with the possibility that, at low phosphate levels, the biosynthesis of cholesterol is limited by some phosphaterequiring reaction(s) in the pathway after mevalonate, and at higher phosphate levels, the biosynthesis is limited by the 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase‐catalyzed step.
Effect of vitamin E on pentane exhaled by rats treated with methyl ethyl ketone peroxide
Authors: Herschberger L. A. , Tappel Al L.
Published: December 2006

One useful method to monitor in vivo lipid peroxidation is the measurement of volatile hydrocarbons, mainly pentane and ethane, that derive from unsaturated fatty acid hydroperoxides. Vitamin E, the biological antioxidant, inhibits lipid peroxidation and the production of pentane and ethane. The rates of pentane production by male Sprague‐Dawley rats fed a diet that contained 10% vitamin E‐stripped corn oil and 0, 1, 3, 5 or 10 IU dl‐α‐tocopherol acetate/kg were monitored over a 12‐wk period. During the eleventh and twelfth weeks, the rats were injected intraperitoneally with 3.3 and 13 mg of methyl ethyl ketone peroxide (MEKP)/kg body wt, respectively. Pentane production was then measured at intervals over a 50‐min period, and the total amount of pentane produced over this time interval was estimated. An asymptotic function was found to describe the relationship between exhaled pentane and the low levels of dietary vitamin E that were fed to the rats. As measured by pentane production, rats had a higher minimal vitamin E requirement after they were treated with the potent peroxidation initiator MEKP than they did prior to treatment. The level of pentane exhaled by rats injected with 13 mg MEKP/kg body wt was significantly correlated with kidney and spleen tocopherol levels.
Hydrolysis of triglycerides in the isolated perfused rat lung
Authors: Compton Suzanne K. , Hamosh Margit , Hamosh Paul
Published: December 2006

The purpose of this study was to investigate the hydrolysis of saturated and unsaturated triglycerides by lung lipoprotein lipase and to measure the incorporation of triglyceride fatty acids into lung tissue lipids. Lipolytic activity was studied in the isolated ventilated rat lung, perfused for 100 min in a recycling system with Krebs Ringer bicarbonate containing bovine serum albumin, 5.6 mM glucose, and 1.5 or 10 mM triglyceride. Saturated triglycerides were hydrolyzed at significantly (p<0.05) lower rates than unsaturated triglycerides; tricaprylin, trimyristin and tripalmitin were hydrolyzed at 8.1+1.8, 5.4+1.5 and 9.5+1.8 μmol free fatty acids/g dry wt/100 min, respectively, whereas triolein and trilinolein were hydrolyzed at 20.2+1.8 and 20.6+0.3 μmol free fatty acids/g dry wt/100 min, respectively. The polyunsaturated triglycerides, trilinolein and triarachidonin were hydrolyzed at even higher rates (44.3+3.0 and 50.9+5.4 μmol free fatty acids/g dry wt/100 min, respectively). Intralipid infused at a concentration of 10 mM triglyceride was hydrolyzed at a significantly higher rate than at 1.5 mM triglyceride (58+6.3 μmol free fatty acids/g dry wt/100 min vs 16.6+1.7 μmol free fatty acids/g dry wt/100 min, respectively). Labeled unsaturated triglycerides were broken down at significantly higher rates than labeled saturated triglycerides. Incorporation of triglyceride‐fatty acid into lung lipid was greater into neutral lipids than into phospholipids. The data suggest that (a) the factors that appear to affect lung lipoprotein lipase activity are composition and concentration of circulating triglyceride, (b) uptake of fatty acids into the tissue was proportional to the rate of hydrolysis of the emulsion, and (c) triglyceride‐fatty acids could therefore be used by the lung for metabolic needs.
cis‐5‐olefinic unusual fatty acids in seed lipids of gymnospermae and their distribution in triacylglycerols
Authors: Takagi Toru , Itabashi Yutaka
Published: December 2006

Open‐tubular gas chromatographic analysis of fatty acids in the lipids from the seeds of 20 species of Gymnospermae showed that they all contained nonmethylene‐interrupted polyenoic (NMIP) acids as minor components and palmitic, oleic, linoleic and α‐linolenic acids as major components. The NMIP acids have an additional 5,6‐ethylenic bond in ordinary plant unsaturated fatty acids and the following C2 elongation acids:cis‐5,cis‐9‐octadecadienoic acid (5,9–18∶2) (I); 5,9,12–18∶3 (II); 5,9,12,15–18∶4, 5,11–20∶2, 5,11,14–20∶3 (III); and 5,11,14,17–20∶4 (IV). The main NMIP acids found in neutral lipids are I in two species ofTaxus, II in seven species of Pinaceae, III in two species of Podocarpaceae,Torreya nucifera, Cycas revoluta, andGinkgo biloba, and III and IV in each of three species of Taxodiaceae, and Cupressaceae. The polar lipids constitute the minor fraction of seed lipids in general. The content and composition of NMIP acids in these lipids differe considerably from those in neutral lipids. Analysis of the partial cleavage products of triacylglycerols showed that the NMIP acids distribute mainly in the 1,3‐position.
Preferential oxidation of linolenic acid compared to linoleic acid in the liver of catfish (Heteropneustes fossilis andClarias batrachus)
Authors: Bandyopadhyay Gautam K. , Dutta Jyotirmoy , Ghosh Sudhamoy
Published: December 2006

The fate of [1‐14C] linoleic acid and [1‐14C] linolenic acid in the liver slices and also in the liver tissues of live carnivorous catfish,Heteropneustes fossilis andClarias batrachus, was studied. Incorporation of the fatty acids into different lipid classes in the live fish differed greatly from the tissue slices, indicating certain physiological control operative in vivo. The extent of desaturation and chain elongation of linoleic and linolenic acids into long‐chain polyunsaturated fatty acids was low. Linolenic acid was oxidized (thus labeling the saturated fatty acid with liberated14C‐acetyl‐CoA) in preference to linoleic acid, and this oxidation also seemed to be under physiological control since both of the fatty acids were poorly oxidized in the tissue slices and in the killed fish. These fish can therefore recognize the difference in the acyl chain structures of linoleate and linolenate. The higher oxidation of liolenic acid and poor capacity for its conversion to longer chain, highly unsaturated derivatives indicates a higher demand for the dietary supply of these essential fatty acids in these two species.
Differential uptake of cholesterol and plant sterols by rat erythrocytes in vitro
Authors: Child P. , Kuksis A.
Published: December 2006

The in vitro uptake of radioactively labeled cholesterol and the plant sterol β‐sitosterol has been examined in rat erythrocytes. From mixed micellar solutions containing egg yolk phospholipid and sodium taurocholate, the erythrocytes showed a nonlinear uptake of the two sterols. The uptake leveled off after about 45 min with the attainment of a 1∶1 total sterol‐to‐phospholipid ratio within the cell membrane, as determined on a mass basis. From soltuions containing egg yolk phospholipid, or purified egg yolk phosphatidylcholine, a preference for cholesterol over the plant sterol was observed, increasing with time from a cholesterol/β‐sitosterol uptake ratio of unity (the media ratio) to a maximum of 2 after a 60‐min incubation. Correction of the data for nonspecifically bound sterol increased the ratio to a maximum of 5 at the 30‐min time point. The increase in the cholesterol/β‐sitosterol uptake ratio with time, following an initial nonspecific association, showed that penetration of the plasma membrane by the sterol was required for the selectivity to be expressed. The presence of lysophosphatidylcholine or bovine serum albumin did not exert any noticeable influence over the extent of selectivity of absorption. Replacement of the egg yolk phospholipid with synthetic dipalmitoyl‐phosphatidylcholine led to a loss of the sterol selectivity. No evidence was found to support a selective extraction of sterol from the erythrocyte membrane to account for the observed effects, nor was there any sign of a mass accumulation of phospholipid during the incubation. It is suggested that the media phospholipid influences the membrane permeability toward cholesterol and β‐sitosterol.
Phospholipids ofRhizobium meliloti andAgrobacterium tumefaciens: Lack of effect of Ti plasmid
Authors: Thompson Emily A. , Kaufman Allan E. , Johnston Norah C. , Goldfine Howard
Published: December 2006

We have studied the phospholipid composition ofRhizobium meliloti strains which do or do not contain the large, tumor‐inducing (Ti) plasmid ofAgrobacterium tumefaciens. The major phospholipids of stationary phase cells were phosphatidylethanolamine (PE) (22%), phosphatidyl‐N‐methylethanolamine (22%), phosphatidylcholine (PC) (27%), phosphatidylglycerol (11.4%), and cardiolipin (11%); as average percent of lipid phosphorus. Phosphatidyl‐N,N‐dimethylethanolamine (3.7%) was also present. The proportions of PE were higher, and PC lower, in logarithmic phase cells. No significant differences were seen in the proportions of phospholipids in strains with or without the Ti plasmid. Qualitative examination of the phospholipids ofA. tumefaciens with or without the Ti plasmid similarly revealed no differences.
Biosynthesis of the novel fatty acid, 17‐methyl‐cis‐9,10‐methyleneoctadecanoic acid, by the parasitic protozoan,Herpetomonas megaseliae
Authors: Holz G. G. , Beach D. H. , Singh B. N. , Fish W. R.
Published: December 2006

Herpetomonas megaseliae, a flagellate protozoan parasite of the gut of a dipteran,Megaselia scalaris, is shown by chromatographic, spectrometric and radiotracer methods to synthesize de novo aniso‐branched chain cyclopropane fatty acid, 17‐methyl‐cis‐9,10‐methyleneoctadecanoic acid.
A comparison of the oleaginous yeast,Candida curvata, grown on different carbon sources in continuous and batch culture
Authors: Evans Christopher T. , Ratledge Colin
Published: December 2006

The oleaginous yeast,Candida curvata D, was grown in both batch and continuous culture on 5 different carbon sources to compare the efficiency of fat production from the various substrates. Maximum lipid accumulation occurred in batch culture with xylose as the carbon source on nitrogenlimited medium reaching a level of 49% (w/w) of the biomass, but this was reduced to 37% at the optimum dilution rate (D=0.05/hr) in a chemostat. Both the highest biomass and lipid yields were attained in continuous culture with lactose as the sole carbon source at a dilution rate of D=0.04/hr, giving an efficiency of substrate conversion of 60 g of biomass and 18.6 g lipid per 100 g lactose utilized. The relative proportions of the major fatty acids (16∶0, 18∶0, 18∶1, 18∶2) in the lipid were found to vary considerably in batch culture and in continuous culture under carbon‐limited conditions. However, on nitrogen‐limited media in the chemostat, the fatty acid composition remained relatively constant over the whole range of dilution rates employed. Lipid from xylose‐grown cells contained the greatest percentage of stearic acid (18∶0) 15% and the lowest linoleic acid (18∶2) 4%, whereas lipid from ethanol‐grown cells contained elevated levels of oleic acid (18∶1) 51% and decreased palmitic acid (16∶0) 25%.
Biochemical activities during lipid accumulation inCandida curvata
Authors: Evans Christopher T. , Ratledge Colin
Published: December 2006

Intracellular and extracellular concentrations of citrate and the specific activities of ten different enzymes inCandida curvata D were examined in relation to lipid biosynthesis in batch and continuous culture. Citrate was found to accumulate prior to lipid production and declined markedly as lipid accumulated in batch culture. The cells excreted citrate as the culture became nitrogen‐limiting after 30 hr of growth, but little more was expelled after 40 hr when lipid accumulation was more marked. In continuous culture, only low levels of citrate were detected at the lower dilution rates and citrate was completely absent from both the cells and medium above a dilution rate of 0.1/hr. The activity of malic enzyme, malate dehydrogenase and ATP:citrate lyase increased in batch culture on lipid accumulated, and, in continuous culture, both malic enzyme and ATP: citrate lyase varied in parallel with the specific rate of lipid synthesis which increased with increasing dilution rate. Activity of malate dehydrogenase, citrate synthase and glucose‐6‐phosphate dehydrogenase decrease with increasing dilution rate. The regulatory significance of these enzymes in lipid accumulation byC. curvata is discussed.
Effect of age on plasma bile acids and lipid components in the rat
Authors: Suzuki Hiramitsu , Hayakawa Seiichi , Tajima Makoto
Published: December 2006

With increasing age, total plasma bile acid contents increased in rats over a period of 11 months, and also total plasma cholesterol and carcass fat contents increased in the same manner. Plasma showing high bile acid levels at 11 months was found by means of high performance liquid chromatography to contain cholic acid as one of the major components, chenodeoxycholic acid and trace deoxycholic acid. These results suggest that there are close relationships between the plasma bile acids and age‐dependent changes of lipid components in the rat.
Lung lipid synthesis from acetoacetate and glucose in developing rats in vitro
Authors: Sheehan Patricia M. , Yeh Yu‐Yan
Published: December 2006

Acetoacetate (AcAc) and glucose were compared as energy sources and as precursors for lipid synthesis in the lungs of developing rats. Minced lung tissue was incubated with [3‐14C]AcAc or [U‐14C]glucose and the oxidation of each substrate to CO2 or its incorporation into tissue lipids was quantified. The highest rates of oxidation were obtained during the first 5 days for AcAc and the first 2 days of life for glucose and oxidation of AcAc was 3–4 times greater than that of glucose at all ages. Throughout postnatal development, the rates of nonsaponifiable lipid, fatty acid and hence total lipid (chloroform/methanol extractable) synthesis from AcAc were 2–3 times those of glucose. The highest rates of total lipid synthesis from AcAc and glucose were observed at birth. Glucose was utilized for glyceride‐glycerol synthesis at a higher rate than AcAc. Similar patterns of incorporation of AcAc and glucose into various lipid classes were noted. Of the total lipids synthesized from AcAc and glucose, respectively, phospholipid plus monoglyceride accounted for 64% and 77%, triglyceride 13% and 13%, diglyceride plus cholesterol 11% and 4% fatty acids 9% and 4%, and cholesteryl esters 3% and 1%. At birth, the specific activities of all lipids except triglyceride derived from AcAc were greater than those from glucose. Rates of synthesis of all complex lipids declined with age. The results of these experiments demonstrate that AcAc is utilized more readily than glucose for energy production and lipid synthesis in developing rat lungs.
Asymmetric distribution of decanoate in triacylglycerol synthesized in vitro by mammary glands of lactating mice
Authors: Rao G. Ananda , Abraham S.
Published: December 2006

Slices, prepared from the mammary glands of lactating mice, were incubated with either [1‐14C]acetate, [U‐14C]glucose, or [1‐14C]decanoate. From all 3 substrates, radioactivity in the synthesized lipids was found mainly in triacylglycerols (TG). When acetate or glucose served as substrate, decanoate (C10) accounted for 24% of the fatty acids in TG. Hydrolysis of the TG by pancreatic lipase yielded [14C] fatty acids which had relatively more C10 (38%) than did either of the other hydrolysis products mono‐ or diacylglycerol (14–17%). However, when TG produced by slices from C10 were hydrolyzed, the acid was found to be esterified equally at the C‐1, C‐2 and C‐3 of glycerol. Thus, when fatty acids are synthesized de novo and are converted to TG by gland slices, C10 is predominantly located in the C‐3 position, a finding in accord with the situation in milk TG, although such preferential incorporation does not occur when the free acid is presented to the tissue slices.