bluuebunny/crossref_metadata_2025 huggingface dataset:
Dietary fiber supplements: Effects on serum and liver lipids and on liver phospholipid composition in rats
Authors: Kritchevskya David , Tepper Shirley A. , Satchithanandam Subramanian , Cassidy Marie M. , Vahouny George V.
Published: November 2006

Rats (6 per group) were fed semipurified diets containing either particulate fibers (alfalfa, 10%; cellulose, 10%; bran, 10%), a soluble ionic fiber (pectin 5%), soluble, nonionic fibers (guar gum, 5%; Metamucil, 10%), a mixed fiber preparation (Fibyrax, 10%, or an insoluble, ionic bile acid‐binding resin (cholestyramine, 2%). The control group was fed the unsupplemented diet. The feeding period, during which diet and water were provided ad libitum, was 28 days.

Compared with the control group, serum total cholesterol levels were increased by more than 10% in rats fed alfalfa and decreased by more than 10% in rats fed cellulose, guar gum, Fibyrax and cholestyramine. There were no significant differences in percentage of plasma HDL cholesterol. Serum triglycerides were elevated in the groups fed alfalfa, pectin, guar gum or Fibyrax and reduced in the group fed Metamucil. Plasma phospholipids were elevated in rats fed alfalfa or bran, unaffected in rats fed pectin or Metamucil and reduced in the other groups. Liver total cholesterol was elevated in all groups but those fed wheat bran and cholestyramine. The percentage of liver cholesterol present as ester was elevated in every group except that fed cholestyramine. Liver triglycerides were reduced in rats fed guar gum or Metamucil and elevated in those fed alfalfa. Liver phospho‐lipids were lowered in the group fed cellulose.

Liver phospholipids were fractionated by thin layer chromatography to give phosphatidylcholine (PC), phosphatidylethanolamine (PE), sphingomyelin (Sph), lysophosphatidylcholine (LPC) and phosphatidylinositol plus phosphatidylserine (PI+PS). PC was elevated in all test groups (7–25%); PE levels ranged from 14% below to 0.3% above controls; Sph levels were sharply lower (20–53%) in all groups. LPC and PI+PS levels were close to the control value in all test groups.

The results demonstrate that different dietary fibers can affect liver phospholipid composition. In view of the critical roles of phospholipids in many biological reactions, it will be interesting to survey the influence of dietary fiber on phospholipid spectra of other tissues.
Changes in plasma lipids, lipoproteins, triglyceride secretion and removal in chicks with estrogen implants
Authors: Park Jeong R. , Cho B. H. Simon
Published: November 2006

Estradiol implants in chicks resulted in marked elevation of all major plasma lipids with greatest increase in triglyceride (TG) followed by phospholipid (PL) and cholesterol (C). During the two‐wk period, plasma TG level in estrogen (E)‐treated chicks increased to about 45 times that of controls (139.6 vs 6,368.3 mg/dl). The level of cholesterol also increased steadily during the same period, attaining nearly a six‐fold increase in comparison with the control (150.7 vs 871.8 mg/dl), and the level of PL was markedly elevated from 209 to 2,861 mg/dl. Besides the induction of hyperlipidemia, E treatment also resulted in a notable alteration in the fatty acid composition of plasma lipids; there was an increase in oleic acid concomitant with a decrease in polyunsaturated fatty acids, particularly, linoleic acid. One day after implantation, the percentage of oleic acid in TG fraction increased from 39.2 to 43.7%, reaching 55.4% of the total fatty acids at day 14. In contrast, the levels of linoleic and arachidonic acid decreased significantly from 16.1 to 8.3% and 4.3 to 0.6%, respectively, during the same period. In cholesteryl ester (CE) and PL, the oleic acid level also increased from 25.2 to 47.3% in the former and from 11.9 to 29.6% in the latter, reflecting enhanced hepatic lipogenesis. Analysis of plasma lipoproteins in E‐treated chicks revealed dramatic alterations in the concentrations of lipids and protein in individual lipoprotein fractions, especially very low density lipoprotein (VLDL) fraction. The respective levels of TG, C and PL in the VLDL fractions were 10.0, 0.6 and 1.0 mg/dl in the control, and 3,904.4, 530.3 and 1,365.2 mg/dl in chicks implanted with estrogen for seven days. The concentrations of TG, C and PL also were markedly increased in the low density lipoprotein (LDL) fraction in these birds. However, the cholesterol content of the high density lipoprotein (HDL) fraction was decreased dramatically in E‐treated chicks (47.1) relative to the control (121.5 mg/dl). The protein level in the VLDL fraction from E‐treated chicks was profoundly elevated to a level 300‐fold greater than controls. TG secretion rates were measured in vivo following the administration of Triton WR‐1339. In control chicks, plasma TG secretion rate was 2.29 mg/min; whereas, chicks treated with E for one and three days showed significantly higher TG secretion rates of 3.18 and 5.27 mg/min, respectively. TG removal rates were measured in vivo after administration of a 10% fat emulsion. Although plasma TG concentrations were different between control and E‐treated birds, no significant differences were found in TG removal rates in those birds, indicating no impairment of TG clearance in E‐treated chicks.
Phospholipid profile and production of prostanoids by murine colonic epithelium: Effect of dietary fat
Authors: Robblee N. M. , Farnworth E. R. , Bird R. P.
Published: November 2006

Dietary fat and abnormal production of various prostanoids have been linked to various disease states of the large bowel, including cancer of the colon. Studies were conducted to determine the effect of dietary fat (beef tallow or corn oil) on the lipid composition and prostanoid production of the murine colon.

Female C57BL/6J mice were fed high‐fat (HF) diets (47% of calories as fat) or low‐fat (LF) diets (10% of calories as fat). After four wk of dietary treatment, the mucosa was scraped, and lipids were extracted from the mucosal and muscle layers. The fat content of the diets did not significantly alter the amount of phospholipid (PL) or neutral lipid in the colonic tissue. However, the HF affected the PL profile of the colonic mucosa. For example, the ratio of phosphatidylcholine (PC) to phosphatidylethanolamine (PE) was significantly higher for both the HF groups compared with that of the two LF groups (0.76±0.15 and 0.80±0.13 vs 0.31±0.20 and 0.34±0.18). Production of 13,14‐dihydro‐15‐keto‐PGE2 (measured as bicyclic PGE2) and TXB2 (a stable metabolite of TXA2) and PGF1α (a stable metabolite of PGI2) was unaffected by the dietary treatments. The muscle had a different PL profile (PC:PE is 2.6±0.1) than the mucosa and contributed a larger proportion of the prostanoids formed. This study demonstrates that the phospholipid polar head group composition of normal colonic mucosa is altered by dietary fat, but the ability of the mucosa to synthesize metabolites of PGE2, TXA2 and PGI2 is not affected.
Characterization of HETEs and related conjugated dienes by UV spectroscopy
Authors: Ingram Christiana D. , Brash Alan R.
Published: November 2006

Three distinct pairs of HETEs can be distinguished on the basis of their UV spectra. We used hydroxy‐linoleates (hydroxy‐octadeca‐cis‐trans‐dienoates) as a base for comparisons; both the 9‐ and 13‐hydroxy isomers have identical chromophores with λmax near 234 nm. The presence of a double bond three carbons removed from the conjugated diene (the chromophore of 9‐ and 11‐HETE) causes a shift in the observed λmax to near 235 nm. A double bond β to the chromophore (5‐ and 15‐HETE) gives a further shift of 1.5 nm, giving a λmax between 236–236.5 nm. With double bonds in both these positions (8‐ and 12‐HETE), the λmax is observed near 237 nm. It is apparent that the exact λmax of thecis‐trans diene chromophore is influenced in a consistent way by the adjacent methylene interruptedcis double bonds.
A new quantitative method for the analysis of monoacylglycerol isomers using13C nuclear magnetic resonance spectroscopy
Authors: Dawe R. D. , Wright J. J. C.
Published: November 2006

Current methods for determining the regiochemistry of monoacylglycerols are lengthy, tedious and aggravated by the ready isomerization of 2‐acyl‐sn‐glycerols. A new method employs a very rapid adsorption chromatography step in which isomerization is kept to a minimum, followed by formation of the isopropylidene derivatives using mild procedures. These cyclic derivatives of 1‐ and 3‐acyl‐sn‐glycerols and 2‐acyl‐sn‐glycerols are stable thermally and display certain characteristic13C NMR resonances. Integration of these resonances yields directly the proportion of monoacylglycerol isomers in the mixture. The method was applied to the analysis of monoacylglycerols produced by enzymatic hydrolysis of synthetic and naturally occurring triacylglycerols.
Differential utilization of long chain fatty acids during triacylglycerol depletion. II. Rat liver after starvation
Authors: Cunnane S. C.
Published: November 2006

Rats starved for 96 hr were shown to have a 94% reduction in liver triacylglycerol. Among the long chain fatty acids in liver triacylglycerol, only stearic acid and arachidonic acid were proportionally increased (2.5 and 6 times, respectively); palmitic and linoleic acids were unchanged, and palmitoleic and oleic acids were proportionally decreased. Stearic and arachidonic acids (mg%) were correlated positively within the triacylglycerol fraction, and both fatty acids varied inversely with total triacylglycerol (mg/g) in fed and starved rats. The utilization of long chain fatty acids from liver triacylglycerol during starvation resulted in selective retention of arachidonic acid and stearic acid and suggests that differential hydrolysis of liver triacylglycerol by hepatic lipase may occur or selective reacylation of these specific fatty acids may occur during starvation.
Thermodynamic characterization of the pretrasition of unilamellar dipalmitoyl‐phosphatidylcholine vesicles
Authors: Lichtenberg Dov , Menashe Moshe , Donaldson Steve , Biltonen Rodney L.
Published: November 2006

High‐sensitivity differential scanning calorimetry of small unilamellar vesicles (SUV) made by sonication of dipalmitoylphosphatidylcholine (DPPC) reveals that the gel‐liquid crystalline transition at 37 C is preceded by a pretransition at 28 C that is relatively slow (t 1/2≃2–4 min) and has an enthalpy change of ca. 0.2 kcal/mol. On incubation at 4 C, these SUV fuse spontaneously into large unilamellar vesicles (LUV). LUV also exhibit both a pretransition and a main‐phase transition. The temperature of the main transition (Tm) and the enthalpy change of both the pretransition and main transition of these fused vesicles are similar to those of large multilamellar vesicles (MLV). The enthalpy change associated with the transition at 28 C decreases in SUV in a manner directly correlated to the decrease in the apparent enthalpy change of the 37 C main transition, indicating that the smaller (low temperature) transition is indeed a pretransition that is an inherent property of SUV. Therefore, unilamellar vesicles of DPPC appear to exhibit a pretransition at a temperature that varies from 28 C for the small vesicles to 35 C for the much larger vesicles.
Hepatic origin of triglycerides in fatty livers produced by the continuous intragastric infusion of an ethanol diet
Authors: Tsukamoto Hidekazu , Lew Gail , Larkin Edward C. , Largman Corey , Ananda Rao G.
Published: November 2006

Male Wistar rats were maintained for 30 days on an independent and continuous intragastric infusion of ethanol and nutritionally defined liquid diet containing only a small amount of corn oil (CO‐4.9% calories). Ethanol intake was progressively increased from 32% to 40.4% of the total calories to maintain a high degree of intoxication during this period. Rats in the control group were infused with an isocaloric diet in which alcohol was replaced by dextrose. The liver triglyceride (TG) content of rats given alcohol (61.5±16.4 mg/g) was ca. 10‐fold greater than that of controls (5.9±2.1 mg/g) and similar to that observed previously in rats fed an ethanol diet containing high levels of fat (35% and 43% calories). In TG of fatty liver, the level of 18∶2 was small (3%), even though CO in the diet contained a high level of this acid. Furthermore, 16∶1 and 16∶0 contents were markedly elevated (16% and 40%, respectively) despite the fact that CO did not contain 16∶1 and had only a small amount of 16∶0. Liver TG having a fatty acid (FA) composition markedly different from that of CO and the presence of high levels of 16∶1 and 16∶0 indicate that the TG accumulated in the fatty liver originated from hepatic lipogenesis rather than from dietary fat.
Composition and metabolism of fatty acids in phospholipids of density‐separated red cells of rats
Authors: Kunimoto Manabu , Kaya Kunimitsu , Miura Takashi
Published: November 2006

Fatty acid compositions of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) and the rates of fatty acid esterification to these phospholipids (PL) were measured in intact rat red cell populations of different ages separated by density gradient centrifugation in order to clarify changes in membrane lipids of red blood cells during in vivo aging. Fatty acid compositions of PC and PE altered progressively as red cells became denser. Changes in unsaturated fatty acids occurred predominantly at the 2‐position of PC and PE and those in saturated fatty acids at both positions. The esterification rates of 5 major fatty acids decreased as red cells became denser and those of oleic acid, linoleic acid and arachidonic acid to both PC and PE of fraction I cells (oldest cells) were 37–51% those of fraction IV cells (youngest cells). Reduction in the rates of fatty acid esterification appeared to occur in the course of red cell maturation because reticulocyte‐enriched cell fractions showed 4.5–14.5 times higher rates of linoleic acid and arachidonic acid esterifications to PC and PE.
Effects of triarimol, tridermorph and triparanol on sterol biosynthesis in carrot, tobacco and soybean suspension cultures
Authors: Hosokawa Glenn , Patterson Glenn W. , Lusby William R.
Published: November 2006

The effects of triarimol, tridemorph and triparanol on sterol biosynthesis in carrot, tobacco and soybean suspension cultures were studied. The 3 plant species normally contain campesterol, stigmasterol and sitosterol as major sterols. Triarimol inhibited demethylation at C 14 and the second alkylation of the side chain in all 3 species. The primary effects of tridemorph were the inhibition of the opening of the 9β,19‐cyclopropane ring and the second alkylation of the side chain. Triparanol treatments resulted in the accumulation of 14α‐methyl sterols, and the inhibition of second alkylation in the side chain in carrot and tobacco cultures. Cyclopropyl sterols also accumulated in carrot and tobacco cultures treated with triparanol. Triparanol did not alter the sterol composition of soybean cultures except for decreasing concentrations of campesterol and stigmasterol and increasing amounts of sitosterol.
A lack of correlation between linoleate and arachidonate in human breast milk
Authors: Gibson R. A. , Kneebone G. M.
Published: November 2006

The levels of arachidonic acid and linoleic acid found in the lipid fraction of human milk samples were compared. No correlation was found between the level of precursor linoleate and product arachidonate in 80 samples of colostrum (day 3–5) or 60 samples of mature breast milk. We attempted to test the hypothesis that the absence of a precursor‐product relationship was caused by a constant level of arachidonate being secreted in the phospholipids (PL) of breast milk cells. Examination of the fatty acid (FA) composition of the PL and triglyceride fractions revealed arachidonate in high concentration in PL but that most of the total arachidonate existed in triglycerides.
The very long chain fatty acids of the green alga,Chlorella kessleri
Authors: Řezanka Tomáš , Podojil Miloslav
Published: November 2006

Fatty acids of the fresh‐water green alga,Chlorella kessleri (heterotrophically cultivated), were fractionated (as methyl esters) using high performance liquid chromatography (HPLC). A fraction of fatty acids with chain lengths longer than 28 carbon atoms was analyzed by gas chromatography‐mass spectrometry (GC‐MS). The very long chain fatty acids, ranging from 31 to 36 carbon atoms, were found for the first time in a green alga.
Preparation and characterization of glucosylated aminoglycerophospholipids
Authors: Ravandi A. , Kuksis A. , Myher J. J.
Published: November 2006

Natural aminophospholipids were isolated from egg yolk and from human red blood cells. Glucosylated ethanolamine and serine phosphatides were prepared by exposing synthetic and natural aminophospholipids to glucose for 3–18 h at pH 7.4. The glucosylation products were resolved from parent phospholipids by normal‐phase high‐performance liquid chromatography and were identified by on‐line mass spectrometry with an electrospray interface. The soft ionization method allowed us to detect the glucosylation products as molecular ions of the Schiff bases. The Schiff bases could be stabilized by sodium cyanoborohydride reduction. The molecular species of the ethanolamine and serine phosphatides reacted in proportion to their molar concentration in the mixtures. The yields of the glucosylation products varied with time of reaction and the concentration of glucose in the medium. At 50 mM glucose and 0.6 mg/mL phosphatidylethanolamine, 20% of the aminophospholipid was glycated in 18 h at 37°C.
Structural importance of thecis‐5 ethylenic bond in the endogenous desaturation product of dietary elaidic acid,cis‐5,trans‐9 18∶2 acid, for the acylation of rat mitochondria phosphatidylinositol
Authors: Wolff Robert L.
Published: November 2006

When rats were fed elaidic (trans‐9 18∶1) acid at a high load in diets that were otherwise marginally or almost completely deficient in linoleic (cis‐9,cis‐12 18∶2) acid, elaidic acid was desaturated tocis‐5,trans‐9 18∶2 acid. This polymethylene‐interrupted acid was then incorporated into most phospholipids from rat mitochondria, cardiolipin being an exception. Its level of esterification in phospholipids followed the increasing order: phosphatidylethanolamine <phosphatidylcholine < phosphatidylinositol (PI). The content ofci‐5,trans‐9 18∶2 acid decreased in organs in the order liver > kidney > heart. The levels ofcis‐5,trans‐9 18∶2 acid increased in mitochondria phospholipids as the level of linoleic acid was lowered in the diet. In liver mitochondria PI, it reached 16% of total fatty acids. After hydrolysis of liver mitochondria PI withNaja naja phospholipase A2, we observed that elaidic acid was essentially esterified to position 1 at the expense of saturated acids, whereascis‐5,trans‐9 18∶2 acid was exclusively esterified to position 2, along with 20∶3n−9 and 20∶4n−6 acids. As a consequence, the sums of saturated andtrans‐9 18∶1 acids on the one hand, and of 20∶3n−9, 20∶4n−6, andcis‐5,trans‐9 18:2 acids on the other hand, remained fairly constant in liver mitochondria PI (ca. 55 and 30%, respectively). Becausetrans‐9 18∶1 andcis‐5,trans‐9 18∶2 acids differ only by thecis‐5 ethylenic bond, which is also present in 20∶3n−9 and 20∶4n−6 acids, this distribution pattern indicates that thecis‐5 double bond, rather than any other ethylenic bond, may be of major structural importance for channeling fatty acids to position 2 of PI.
A temperature‐sensitive strain ofHistoplasma capsulatum has an altered Δ9‐fatty acid desaturase geneacid desaturase gene
Authors: Gargano Silvana , Di Lallo Gustavo , Kobayashi George S. , Maresca Bruno
Published: November 2006

We have isolated and characterized the Δ9‐desaturase gene (Ole1), which codes for a key enzyme involved in regulating membrane fluidity in animal cells and microorganisms, from two strains ofHistoplasma capsulatum, one that is temperature‐tolerant (G217B) and the other temperature‐susceptible (downs). These pathogenic fungi are dimorphic in that they undergo a morphologic transition from the mycelial to yeast‐like form when the temperature of incubation is switched from 25 to 37°C or when they infect a susceptible host. The coding sequences of the two genes, both containing an intron of 93 nucleotides, arevirtually identical and analogous to the Δ9‐desaturase gene ofSaccharomyces cerevisiae and those of the rat, mouse and human.Ole1 transcription of the thermotolerant G217B and thermosensitive Downs strains is similar in yeast phase cells and during the temperature shift down from 34, 37, or 40 to 25°C (yeast‐to‐mycelia transition). Nevertheless, Δ9‐desaturase gene is transcriptionally inactive in mycelia of G217B at 25°C while it is actively transcribed in the Downs strain at the same temperature. These results are in agreement with the finding that membranes of the Downs strain have a higher level of oleic acid. The differential expression of Δ9‐desaturase genes is discussed in relationship to differences in thermosensitivity in the fungal isolates and in regulating the level of expression of heat shock genes.
Intestinal and liver fatty acid binding proteins differentially affect fatty acid uptake and esterification in L‐cells
Authors: Prows Daniel R. , Murphy Eric J. , Schroeder Friedhelm
Published: November 2006

Differential effects of intestinal (I‐FABP) or liver (L‐FABP) fatty acid binding proteins on fatty acid uptake and esterification were examined using transfected mouse L‐cell fibroblasts. L‐FABP, but not I‐FABP, expression increased the initial rate and extent ofcis‐parinaric acid uptake by 50 and 29%, respectively, compared to control cells. I‐FABP and L‐FABP expression preferentially increased [3H]‐oleic acid incorporation into triacylglycerols by 5.5‐fold and 3.8‐fold, respectively. While both L‐FABP and I‐FABP increasedesterification of [3H]‐oleic acid into ethanolamine glycerophospholipids, these proteins had opposite effect on esterification into choline glycerophospholipids. These data show for the first time that distinct FABP differentially affect both fatty acid uptake and intracellular esterification.
Effects of randomization of partially hydrogenated corn oil on fatty acid and cholesterol absorption, and tissue lipid levels in rats
Authors: Koga Tamiho , Yamato Takako , Ikeda Ikuo , Sugano Michihiro
Published: November 2006

Randomization of partially hydrogenated corn oil containing approximately 45% oftrans octadecenoic acid only slightly, but not significantly, increased the lymphatic fatty acid absorption in rats. No effect of randomization was observed on cholesterol absorption. When rats were fed these fats at the 8.8% level (with 1.2% safflower oil) for three weeks, the concentrations of serum cholesterol, and serum and liver phospholipid were significantly higher in randomized fat than in control fat, which was composed of 9% high‐oleic safflower oil and 1% palm oil. Liver cholesterol tended to be higher in randomized fat. In contrast, nonrandomized fat was not hyperlipidemic compared to control fat. Although the fatty acid composition of liver phospholipids suggested a possible interference oftrans fatty acid with the metabolism of linoleic acid to arachidonic acid, there was no effect of randomization. In the two hydrogenated fat groups,trans octadecenoic acid was incorporated and distributed similarly in adipose tissue triacylglycerol. These observations indicated that randomization of partially hydrogenated fat is not beneficial to various lipid parameters in rats.
Erythrocyte fatty acids of term infants fed either breast milk, standard formula, or formula supplemented with long‐chain polyunsaturates
Authors: Makrides Maria , Neumann Mark A. , Simmer Karen , Gibson Robert A.
Published: November 2006

The purpose of our study was to assess whether a supplement of fish oil (FO) and evening primrose oil (EPO) for formula‐fed infants was capable of avoiding reductions in erythrocyte docosahexaenoic acid (DHA, 22∶6n−3) and arachidonic acid (AA, 20∶4n−6) associated with standard formula feeding. Healthy, term infants, whose mothers chose to formula feed, were randomized to either a placebo or supplemented formula for their first 30 wk of life. A reference group of beast‐fed infants also was enrolled. Erythrocyte fatty acids were measured by capillary gas chromatography on day 5 and in weeks 6, 16, and 30. Supplementation of formula with 0.36% of total fatty acids as DHA resulted in erythrocyte DHA being maintained at or above breast‐fed levels for the entire 30‐wk study period, and breast feeding (0.21% DHA) resulted in a modest fall in erythrocyte DHA relative to baseline (day 5) values. The level of erythrocyte DHA in placebo formula‐fed infants was halved by week 16. AA levels decreased in all infants in the first six weeks, but the levels in breast‐ and placebo formula‐fed infants increased with age and returned to approximate baseline (day 5) values by 16 and 30 wk of age, respectively. Erythrocyte AA in FO+EPO‐supplemented infants remained low and below breast‐ and placebo formula‐fed levels. Our data suggest that dietary supplementation with DHA at 0.36% total fatty acids results in erythrocyte DHA levels above those found in breast‐fed infants. EPO supplementation was not effective at maintaining erythrocyte AA when given with FO.
Differences in fatty acid composition of immature and mature articular cartilage in humans and sheep
Authors: Cleland Katherine A. , James Michael J. , Neumann Mark A. , Gibson Robert A. , Cleland Leslie G.
Published: November 2006

Chondrocytes are imbedded in an avascular, highly charged extracellular matrix which could form a barrier to the transfer of dietary essential fatty acids (EFA) to chondrocytes. A study was designed to assess the composition of immature and mature joint cartilage with respect to essential and nonessential fatty acids relevant to EFA deficiency. Cartilage and muscle samples were obtained from human fetus, infant and adult cadavers, and from fetal and mature sheep. Lipid extracts were prepared and the fatty acid composition determined. In human and sheep joint cartilage, linoleic acid (LA; 18∶2n−6) content was lower, and n−9 eicosatrienoic acid (ETrA; 20∶3n−9) and arachidonic acid (AA; 20∶4n−6) were higher in fetuses compared to mature subjects. An intermediate pattern was seen in infant cartilage. n−3 Fatty acids tended to be higher in fetal than in mature cartilage in humans and in sheep. In human muscle (and in other noncartilaginous comparison tissues), similar differences between fetuses and adults were seen in LA and AA, but not in ETrA. In fetal sheep muscle, very low LA, reduced AA and raised ETrA levels compared to mature sheep muscle were seen. However, although the pattern is characteristic of EFA deficiency, the abundance of n−6 EFA in liver and spleen of human fetuses and of n−3 EFA in liver and spleen of fetal sheep suggests that placental transfer of EFA is not likely to be limiting. During fetal development, the metabolism of fatty acids is distinctive and differs between the species. ETrA appears to be a readily measurable component of some tissues at certain stages of development when its presence in tissues does not indicate EFA deficiency.
Modulation by sphingosine of substrate phosphorylation by protein kinase C in bovine mammary gland
Authors: Katoh Norio
Published: November 2006

The effect of sphingosine on the phosphorylation of endogenous proteins by protein kinase C (PKC) was investigated in bovine mammary gland. Several proteins were shown to be substrates for PKC in both cytosolic and total particulate fractions by phosphorylation in the absence or presence of 1‐oleoy‐2‐acetyl‐sn‐glycerol, phosphatidylserine (PS) and Ca2+. At concentrations of 83 μM or less, sphingosine inhibited phosphorylation of several substrates for PKC in both fractions. Phosphorylation of cytosolic 36 kDa, 21 kDa and particulate 36 kDa proteins was particularly sensitive to sphingosine. Cytosolic 97 kDa phosphorylation (which was enhanced by Ca2+ alone) was also sensitive to sphingosine. The inhibition was reversed by excess addition of lipid cofactors, particularly PS, but not by Ca2+. At higher concentrations (167 and 417 μM), in addition to the inhibition seen at lower concentrations, sphingosine stimulated phosphorylation of several proteins, including cytosolic 19 kDa and particulate 53 kDa, which were not detected in the absence of sphingosine. The sphingosine‐induced phosphorylation disappeared with excess addition of PS, but not with addition of Ca2+. The results point toward the importance of the interaction of sphingosine with membrane phospholipids in the signal transduction pathway mediated by PKC‐dependent phosphorylation in bovine mammary gland.
Intravenous injection of tridihomo‐γ‐linolenoyl‐glycerol into mice and its effects on delayed‐type hypersensitivity
Authors: Taki Hirofumi , Nakamura Norio , Hamazaki Tomohito , Kobayashi Masashi
Published: November 2006

Highly purified tridihomo‐γ‐linolenoyl‐glycerol (DGLA‐TG) was emulsified with egg yolk lecithin as a 10% (wt/vol) DGLA‐TG emulsion. We injected 0.05 or 0.5 mL of the emulsion into mice through the tail vein and investigated its effects on the fatty acid composition of spleen cells and on delayed‐type hypersensitivity (DTH) response. At 1 h after the injection, dihomo‐γ‐linolenic acid (DGLA) concentrations were increased significantly in the total phospholipid fraction of spleen cells from 1.21±0.13 mol% to 2.09 ±0.74 mol% (P<0.02) and 7.95±1.25 mol% (P<0.001) in the 0.05‐mL and 0.05‐mL groups respectively. Mice, which had already been immunized with sheep red blood cells (SRBC), were challenged by the injection of SRBC into the right‐hind footpad. Intravenous injection into mice with 0.5 mL of the emulsion immediately before the challenge almost completely suppressed DTH response measured by the swelling of the right‐hind footpads 24 h thereafter. This inhibitory effect on the DTH response was significant with as little as 0.05 mL of the emulsion, whereas a soybean oil emulsion was not effective at all. In conclusion, intravenous injection of a DGLA emulsion increased DGLA concentrations in immune cells within 1 h and suppressed the DTH reaction.
pH‐dissociation characteristics of cardiolipin and its 2′‐deoxy analogue
Authors: Kates Morris , Syz Jing‐Yi , Gosser David , Haines Thomas H.
Published: November 2006

Cardiolipin (CL) is found in inner mitochondrial membranes and the plasma membrane of aerobic prokaryotes. CL is tightly bound to those transmembrane enzymes associated with oxidative phosphorylation. CL has earlier been reported to have a single pK at low pH. We have titrated CL in aqueous suspension (bilayers) and in solution in methanol/water (1∶1, vol/vol) and found it to display two different pK values, pK1 at 2.8 and pK2 initially at 7.5 but shifting upwards to 9.5 as the titration proceeds. The unusually high pK2 might be explained by the formation of a unique hydrogen bond in which the free hydroxyl on the central glycerol forms a cyclic intramolecular hydrogen‐bonded structure with one protonated phosphate (P‐OH group). We have therefore chemically synthesized the 2′‐deoxycardiolipin analogue, which lacks the central free hydroxyl group, and measured its pH‐dissociation behavior by potentiometric titration, under the same conditions as those for CL. The absence of the hydroxyl group changes the titration dramatically so that the deoxy analogue displays two closely spaced low pK values (pK1=1.8; pK2=4.0). The anomalous titration behavior of the second dissociation constant of CL may be attributed to the participation of the central glycerol OH group in stabilizing the formation of a cyclic hydrogen‐bonded monoprotonated form of CL, which may function as a reservoir of protons at relatively high pH. This function may have an important bearing on proton pumping in biological membranes.
Modulating effects of bile salt hydrophobicity on bile secretion of the major protein of the bile lipoprotein complex
Authors: Domingo Nicole , Chanussot Françoise , Botta Danielle , Reynier Marie‐Odile , Crotte Christian , Hauton Jacques , Lafont Huguette
Published: November 2006

Bile lipids are secreted in association with a newly identified major apoprotein called anionic polypeptide fraction‐calcium binding protein (APF‐CBP), which is synthesized in the hepatocytes and has been detected in both bile and plasma and characterized. The secretion of the lipids in bile depends both on the concentration and the hydrophobicity of the bile salts (BS) secreted. The present study was undertaken to determine whether the synthesis and the secretion of APF‐CBP are similarly regulated by BS, using two methods. The synthesis and secretion of labelled, newly synthesized APF‐CBP by isolated rat hepatocytes were monitored by solid‐phase immunoassay. For this purpose, hepatocytes were incubated with either glycodeoxycholate (GDC) or taurocholate (TC). The synthesis and secretion of labelled, newly synthesized APF‐CBP by perfused rat liver were measured by immunological enzyme‐linked assay (ELISA) upon perfusing the liver with either GDC or TC. We found that (i) the synthesis and the secretion of APF‐CBP were increased during either TC or GDC perfusion, but the increase was more pronounced with TC; (ii) in GDC perfusion the APF‐CBP levels measured were more closely related to the levels of bile salts and not to phospholipid levels, (iii) when the two bile salts were perfused in reverse order,i.e., first GDC and then TC, the secretion of APF‐CBP in bile decreased when GDC was perfused, but increased when TC was perfused. Similar results were obtained in experiments with isolated hepatocytes. The data suggest that the hydrophobicity of the BS used in the infusion modulates the synthesis and secretion of APF‐CBP. In the liver, the pool of APF‐CBP can be modified by BS and responds rapidly to BS stimulation.
On the syntheses of branched saturated fatty acids
Authors: Gronowitz Salo , Klingstedt Tomas , Svensson Leif , Hansson Ulf
Published: November 2006

In order to investigate the relation between the structure of mono‐branched saturated fatty acids and their physical properties, a three‐factor central composite design was constructed. For this purpose sixteen different fatty acids were prepared. The synthetic strategy was to use if possible, a few common starting materials for the preparation of most of the acids. Thus alkylation and hydrolysis of oxazolines were used for the preparation of 2‐butylhexanoic acid, 2‐methyloctadecanoic acid, 2‐hexadecyloctadecanoic acid and 2‐pentyloctadecanoic acid. A number of acids were prepared from thiophene derivatives followed by desulfurization with Raney‐Nickel alloy under alkaline conditions. Thus, starting from 3‐ethylthiophene, 4‐ethyl‐2‐thiophenecarboxylic acid and 4‐ethyl‐2‐methyl‐5‐thiophenecarboxylic acid were prepared, which upon desulfurization gave the desired 4‐methylhexanoic acid. From 3‐bromo‐2‐methylthiophene, 3‐ethyl‐2‐methyl‐5‐thiophenecarboxylic acid was preparedvia 3‐acetyl‐2‐methylthiophene and 3‐ethyl‐2‐methylthiophene. Desulfurization gave 4‐ethylhexanoic acid. Another approach started with 2‐acylthiophenes, which were reacted with Grignard reagent to yield the appropriate olefins. By metalation and reaction with carbon dioxide, these were transformed to the corresponding 2‐thiophenecarboxylic acids. Upon desulfurization, the desired fatty acids were obtained. In this way 6‐propyldecanoic acid, 6‐hexyldodecanoic acid, 6‐methyldodecanoic acid and 6‐pentylpentadecanoic acid were prepared. The remaining four acids were prepared from some of the branched acids described above through Kolbe reactions of dioic acids. Thus 16‐methyloctadecanoic acid and 10‐methyl‐dodecanoic acid were obtained from 4‐methylhexanoic acid, 16‐ethyloctadecanoic acid from 4‐ethylhexanoic acid and 9‐pentyloctadecanoic acid from 6‐pentylpentadecanoic acid.
Effect of lipid content of diet on cholesterol content and cholesterogenic enzymes of European eel liver
Authors: Burgos C. , Zafra M. F. , Castillo M. , Garcia‐Peregrin E.
Published: November 2006

The effect of dietary lipid levels on the levels of cholesterol and the activities of the major cholesterogenic enzymes of the liver has been studied in the European eel. An increase in hepatic total cholesterol was observed when the dietary lipid levels increased from 12 to 20%, while protein levels were maintained at 30%. This change paralleled an increase in mevalonate 5‐pyrophosphate decarboxylase activity, while 3‐hydroxy‐3‐methylglutaryl‐CoA reductase, mevalonate kinase and mevalonate 5‐phosphate kinase were not affected by changes in diet composition. These results suggest that the decarboxylase may be a rate‐limiting enzyme in cholesterogenesis in eel liver.
Cholesterol and 25‐hydroxycholesterol retention in specimens of liver and aorta prepared for electron microscopy. I. Standard fixation methods and metabolism of the labeled sterols
Authors: Fornas E. , Renau‐Piqueras J. , Fortea A. , Mayordomo F. , Alborch E.
Published: November 2006

In the present work, several preparatory procedures commonly used for electron microscopy (EM) were evaluated as to their ability to preserve cholesterol (CHO) and CHO derivatives in tissue. We also determined in several rat tissues to what extent the sterols used as tracers are metabolized. Sprague‐Dawley rats were injected intraperitoneally with [1α,2α(n)‐3H]cholesterol ([3H]CHO) and 25‐hydroxy‐[26,27‐3H]cholesterol ([3H]25‐OH−CHO). Lipids of the liver, aorta and brain were extracted one and five days after injection, and the distribution of the labeled lipids was followed by thin‐layer chromatography. When labeled CHO was injected as tracer, most of the radioactivity remained associated with the CHO fraction. When 25‐hydroxycholesterol (25‐OH−CHO) was used, we found that it was mostly metabolized to yield more polar compounds. Our results show that the loss of CHO and CHO derivatives from tissues depends not only on the preparatory procedure used for EM, but also on the type of tissue studied.
The effect of lyophilization on the solvent extraction of lipid classes, fatty acids and sterols from the oysterCrassostrea gigas
Authors: Dunstan Graeme A. , Volkman John K. , Barrett Stephanie M.
Published: November 2006

The lipid class compositions of adult Pacific oysters [Crassostrea gigas (Thunberg)] were examined using latroscan thin‐layer chromatography/flame‐ionization detection (TLC/FID), and fatty acid compositions determined by capillary gas chromatography and gas chromatography/mass spectrometry (GC/MS). The fatty acid methyl esters were separated using argentation TLC and also analyzed as their 4,4‐dimethyloxazoline derivatives using GC/MS. Major esterified fatty acids inC. gigas were 16∶0, 20∶5n−3, and 22∶6n−3. C20 and C22 nonmethylene interrupted (NMI) fatty acids comprised 4.5 to 5.9% of the total fatty acids. The NMI trienoic fatty acid 22∶3(7,13,16) was also identified. Very little difference was found in the proportions of the various lipid classes, fatty acids or sterols between samples of adult oysters of two different sizes. However, significant differences in some of the lipid components were evident according to the method of sample preparation used prior to lipid extraction with solvents. Lyophilization (freeze drying) of samples led to a significant reduction in the amounts of triacylglycerols (TG) extracted by solvents in two separate experiments (7.0 and 52.5% extracted). Extracts from lyophilized samples had less 16∶0, C18 unsaturated fatty acids, and 24‐ethylcholest‐5‐en‐3β‐ol, while C20 and C22 unsaturated fatty acids comprised a higher proportion of the total fatty acids. There was no significant change in the amounts of polar lipids, total sterols, free fatty acids or hydrocarbons observed in extracts from lyophilized samples relative to extracts from nonlyophilized samples. Addition of water to the freezedried samples prior to lipid extraction greatly improved lipid yields and resulted in most of the TG being extracted.
A micro enzymic method for determination of choline‐containing phospholipids in serum and high density lipoproteins
Authors: Nie Ying , He Jin Lin , Hsia S. L.
Published: November 2006

A micro method is described for the assay of choline‐containing phospholipids in serum and high density lipoproteins (HDL) using an automated microtiter plate reader. The method is adapted from the enzymic method of Takayama, Itoh, Nagasaki, and Tanimuzu (Clin. Chim. Acta 79, 93–98, 1977) using phospholipase D, choline oxidase, and peroxidase coupled with the color generating system phenol and 4‐amino‐antipyrine. The micro method requires 5 μL of serum or HDL sample, and 42 samples can be assayed in duplicate in one run using a 96‐well flat‐bottom microtiter plate. The reaction is linear up to 400 mg/dL and the lower limit of detection is 0.25 mg of choline‐containing phospholipids per assay. The coefficient of variation within an assay is 0.86–0.79%, and day‐to‐day variation is 0.9–1.5%. Results obtained by the micro method are in excellent agreement with those obtained by the procedure of Takayamaet al. (r=0.997). The supernatant left after removal of low density lipoproteins and very low density lipoproteins from serum and precipitation with heparin/manganese chloride reagent can thus be conveniently used for the micro assay of choline phospholipids in HDL.
Peroxisomes in mice fed a diet supplemented with low doses of fish oil
Authors: Van den Branden C. , De Craemer D. , Pauwels M. , Vamecq J.
Published: November 2006

The influence of low dietary doses (0.1 and 0.8% w/w) of a commercial fish oil preparation on peroxisomes in normal mice was studied and compared to the known strong inductive effects of high (10%) fish oil diets. Low fish oil doses were chosen to supply the mice with a concentration of docosahexaenoic acid, which was beneficial to patients with a peroxisomal disease. Peroxisomes were evaluated by cytochemical, morphometric, and enzymological techniques. The 0.1% fish oil diet had no effect on peroxisomes in liver, heart, and kidney even after prolonged treatment. The 0.8% diet did not change the peroxisomal number nor the catalase (EC 1.11.1.6) activity in the liver. Hepatic peroxisomal β‐oxidation, however, was increased by 50% after 14 d. This was accompanied by reduced peroxisomal size. The 0.8% diet also caused a small increase (+25%) in myocardial catalase activity. No effect was observed in kidneys. Our results indicate that in mice a low (<0.8%) dietary fish oil dose has no or only a slight effect on hepatic peroxisomal β‐oxidation. This may be of particular interest to patients with a peroxisomal fatty acid β‐oxidation defect and who display a severe deficiency of docosahexaenoic acid—diets supplemented with low fish oil doses will improve the docosahexaenoic acid level without adding a strong load to the disturbed fatty acid metabolism.
Phospholipid molecular species composition of developing fetal guinea pig brain
Authors: Burdge Graham C. , Postle Anthony D.
Published: November 2006

Adequate accumulation of polyunsaturated essential fatty acids, in particular docosahexaenoic acid (22∶6n−3), into membrane phospholipids is critical for optimal fetal brain development. This process is maximal during the period of rapid neurite outgrowth, neuritogenesis, which precedes the major growth phase, myelination. There is no information about differential changes during gestation to individual brain phospholipid molecular species which contain 22∶6n−3. Such details of brain development would be concealed by total fatty acid analysis of isolated phospholipid classes. We have detailed phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecular species compositions in developing fetal guinea pig brain. Total brain PC concentration increased substantially between 40 and 68 (term) d of gestation, corresponding to myelination, while PE increased in a biphasic manner between 25–35 d, which was coincident with onset of neuritogenesis, and 40–68 d. Fetal brain development was accompanied by complex changes in the concentration of individual phospholipid molecular species. During early gestation (25–40 d) 22∶6n−3 was enriched in both PC and PEsn−1 16∶0 molecular species. However, between 40 d and term there was no further increase in brain PC 22∶6n−3 content, while brain PE was significantly enriched in both PE 18∶1/22∶6 and PE18∶0/22∶6. We hypothesize that accumulation of 22∶6n−3 intosn−1 18∶1 and 18∶0 species represents establishment of a 22∶6n−3‐containing membrane PE pool which may be turned over more slowly thansn−1 16∶0 species. Identification of specific changes in membrane phospholipids which are associated with defined events in brain development may provide a basis for assigning functional roles to individual molecular species.
Cucumber cotyledon lipoxygenase oxygenizes trilinolein at the lipid/water interface
Authors: Matsui K. , Kajiwara T.
Published: November 2006

The reactivity of cucumber cotyledon lipoxygenase with trilinolein was examined. The activity of the enzyme against linoleic acid rapidly decreased with increasing pH of the assay solution, and essentially no activity could be detected above pH 8.5. The rapid decrease in activity was not the result of an inactiveness of the enzyme at alkaline pH, because with trilinolein, the enzyme showed a broad pH‐activity profile, and substantial activity could be detected even at pH 9.0. Rather, the decrease in activity was due to the dissociation of the linoleic acid emulsion into acid‐soap aggregates and/or the monomeric form, depending on the ionization of the terminal carboxylic group. This suggests that cucumber cotyledon lipoxygenase acts only on an insoluble substrate at the lipid/water interface but not on a soluble one. High‐performance liquid chromatography analyses of the products formed from trilinolein revealed that the enzyme inserted oxygen into the acyl moiety of trilinolein without hydrolysis of the ester bonds. Preincubation of the enzyme with triolein emulsions effectively abolished its activity against trilinolein added afterward. Furthermore, the enzyme was adsorbed on the trilinolein or triolein emulsion droplets in an essentially irreversible manner. A reaction velocity curve of the enzyme with trilinolein showed saturation kinetics. This is thought to be due to a regional substrate deficiency as the reaction proceeds. These lines of evidence indicate that the enzyme, once bound to the lipid/water interface, is unable to break free and bind to other emulsions.
Inhibition of neutral cholesteryl ester hydrolase by the glycolytic enzyme enolase. Is this a secondary function of enolase?
Authors: Shand John H. , West David W.
Published: November 2006

There is an accumulation of the glycolytic enzyme enolase and of cholesteryl esters in macrophages that have been converted into “foam” cells. In this study, we questioned whether enolase could be involved in this accumulation of cholesteryl esters by inhibiting the activity of neutral cholesteryl ester hydrolases. Enolase from both yeast and rabbit muscle were incubated with three different cholesteryl ester hydrolases and were shown to inhibit the hydrolysis of cholesteryl esters. Inhibition was dependent on the concentration of enolase and appeared to occur through binding of the enolase to the cholesteryl ester. Nevertheless, the yeast and rabbit muscle enolases differed in their efficiency of inhibition and in their mechanism of action. Purification of commercial enolase preparations by gel‐filtration yielded single proteins with the same inhibitory activities as the originals, indicating that the inhibition was not due to the presence of an impurity. Partially purified αα‐and γγ‐isoforms of the enzyme from rat brain also appear to have inhibitory effects on cholesteryl ester hydrolysis. Negative control of the hydrolytic phase of the cholesterol/cholesteryl ester cycle may be a secondary function of enolases which correlates with the accumulation of cholesteryl esters in a number of neuro‐degenerative and demyelinating diseases.