bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of dietary α‐linolenic acid and its ratio to linoleic acid on platelet and plasma fatty acids and thrombogenesis
Authors: Chan Joanna K. , McDonald Bruce E. , Gerrard Jon M. , Bruce Vivian M. , Weaver Bonnie J. , Holub Bruce J.
Published: November 2006

The effect of dietary α‐linolenic acid (18∶3n−3) and its ratio to linoleic acid (18∶2n−6) on platelet and plasma phospholipid (PL) fatty acid patterns and prostanoid production were studied in normolipidemic men. The study consisted of two 42‐d phases. Each was divided into a 6‐d pre‐experimental period, during which a mixed fat diet was fed, and two 18‐d experimental periods, during which a mixture of sunflower and olive oil [low 18∶3n−3 content, high 18∶2/18∶3 ratio (LO‐HI diet)], soybean oil (intermediate 18∶3n−3 content, intermediate 18∶2/18∶3 ratio), canola oil (intermediate 18∶3n−3 content, low 18∶2/18∶3 ratio) and a mixture of sunflower, olive and flax oil [high 18∶3n−3 content, low 18∶2/18∶3 ratio (HI‐LO diet)] provided 77% of the fat (26% of the energy) in the diet. The 18∶3n−3 content and the 18∶2/18∶3 ratio of the experimental diets were: 0.8%, 27.4; 6.5%, 6.9; 6.6%, 3.0; and 13.4%, 2.7, respectively. There were appreciable differences in the fatty acid composition of platelet and plasma PLs. Nevertheless, 18∶1n−9, 18∶2n−6 and 18∶3n−3 levels in PL reflected the fatty acid composition of the diets, although very little 18∶3n−3 was incorporated into PL. Both the level of 18∶3n−3 in the diet and the 18∶2/18∶3 ratio were important in influencing the levels of longer chain n−3 fatty acid, especially 20∶5n−3, in platelet and plasma PL. Production of 6‐keto‐PGF1α was significantly (P<0.05) higher following the HI‐LO diet than the LO‐HI diet although dietary fat source had no effect on bleeding time or thromboxane B2 production. The present study showed that both the level of 18∶3n−3 in the diet and its ratio to 18∶2n−6 were important in influencing long‐chain n−3 fatty acid levels in platelet and plasma PL and that prostanoid production coincided with the diet‐induced differences in PL fatty acid patterns.
Effect of diets rich in linoleic or α‐linolenic acid on phospholipid fatty acid composition and eicosanoid production in atlantic salmon (Salmo salar)
Authors: Gordon Bell J. , Dick James R. , Sargent John R.
Published: November 2006

Atlantic salmon post‐smolts were fed diets rich in linoleic acid (sunflower oil, SO), α‐linolenic acid (linseed oil, LO) or long‐chain polyunsaturated fatty acids (fish oil, FO) for a period of 12 wk. In the liver phospholipids of fish fed SO, the levels of 18∶2n−6, 20∶2n−6, 20∶3n−6 and 20∶4n−6 were significantly elevated compared to both other treatment. In choline phospholipids (CPL), ethanolamine phospholipids (EPL) and phosphatidylserine (PS) the levels of 22∶4n−6 and 22∶5n−6 were significantly elevated in fish fed SO. In liver phospholipids from fish fed LO, 18∶2n−6, 20∶2n−6 and 20∶3n−6 were significantly elevated but 20∶4n−6, 22∶4n−6 and 22∶5n−6 were similar or significantly decreased compared to fish fed FO. Liver phospholipids from fish fed LO had increased 18∶3n−3 and 20∶4n−3 compared to both other treatments while EPL and phosphatidylinositol (PI) also had increased 20∶5n−3. In fish fed LO, 22∶6n−3 was significantly reduced in CPL, PS and PI compared to fish fed FO. Broadly similar changes occurred in gill phospholipids. Production of 12‐lipoxygenase metabolites in isolated gill cells stimulated with the Ca2+‐ionophore A23187 were significantly reduced in fish fed either SO or LO compared to those fed FO. However, the ratio 12‐hydroxy‐5,8,10,14‐eicosatetraenoic acid (12‐HETE)/12‐hydroxy‐5,8,10,14,17‐eicosapentaenoic acid (12‐HEPE) was significantly elevated in stimulated gill cells from SO‐fed fish. Although mean values of thromboxane B2 (TXB2) and prostaglandin E2 (PGE2) were increased in fish fed SO, they were not significantly different from those of the other two treatments.
Dietary fish oil inhibits human breast carcinoma growth: A function of increased lipid peroxidation
Authors: Gonzalez Michael J. , Schemmel Rachel A. , Dugan LeRoy , Gray J. Ian , Welsch Clifford W.
Published: November 2006

Female athymic nude mice were implanted subcutaneously with human breast carcinoma MDA‐MB231. Seven to ten days later, the mice were divided into groups and fed a purified diet containing the following types of fat (% of diet):(i) 20% corn oil (CO); (ii) 15% CO:5% fish (menhaden) oil (FO); (iii) 10% CO:10% FO; (iv) 5% CO:15% FO; (v) 1% CO:19% FO; and (vi) 1% CO:19% FO plus antioxidants (α‐tocopherol acetate, 2000 IU/kg diet and tertiary butyl‐hydroquinone, 2% of the total fat). The linoleic acid levels (% of diet) of the groups were 12.0, 9.1, 6.2, 3.3, 0.9 and 0.9%, respectively. After 6–8 wk, the carcinomas were assessed for tumor volume (cm3) and assayed for thiobarbituric acid reactive substances (TBARS). Human breast carcinoma growth was suppressed in mice consuming FO diets without antioxidants as compared to mice fed CO; the greater the amount of dietary FO fed, the greater the carcinoma growth suppression (P<0.05). The addition of antioxidants to the FO diet significantly (P<0.05) reversed the FO‐induced carcinoma growth suppression. Concentrations of TBARS in the human breast carcinomas were increased in all the FO (without antioxidants) fed mice, compared to mice fed CO; the level of increase in TBARS was directly related to the increase in the level of FO fed (P<0.05). The addition of antioxidants to the FO diet significantly (P<0.05) reduced the concentration of TBARS in the breast carcinomas. Thus, these results provide evidence that dietary FO can significantly suppress growth of human breast carcinoma MDA‐MB231, even in the presence of substantial amounts of linoleic acid (3.3–9.1%). The inhibitory effect of FO on growth of these carcinomas was associated with an increased concentration of TBARS in the tumor tissue. In conclusion, dietary FO induced suppression of human breast carcinoma growth is a function, at least in part, of an accumulation of lipid peroxidation products in the tumor tissues.
Higher levels of plasma cholesterol sulfate in patients with liver cirrhosis and hypercholesterolemia
Authors: Tamasawa Naoki , Tamasawa Atsuko , Takebe Kazuo
Published: November 2006

An analytical method for the determination of cholesterol sulfate (CS) in plasma using gas‐liquid chromatography was developed. We measured plasma CS concentrations in patients with liver cirrhosis and hypercholesterolemia as examples of disorders that involve aberrations in cholesterol metabolism. Patients with liver cirrhosis had plasma CS concentrations that were significantly higher than those of control subjects (444.6±51.7vs. 253.0±24.6 μg/dL, mean ±SE). The levels of other lipids were lower in cirrhotics, although the differences were not significant. There was no correlation between the levels of CS and sulfated bile acids in cirrhotic patients. CS levels in plasma were also higher in subjects with hypercholesterolemia (413.7±44.5 μg/gL) however, the ratio of CS to total cholesterol (TC) clearly differed between cirrhotics and hypercholesterolemic subjects (1.44±0.11×10−3,vs. 3.31 ±0.63×10−3;P<0.05). Both in subjects with hypercholesterolemia and in healthy controls, the CS/TC ratio was similar and CS accounted for roughly 0.14% of the TC concentration.
γ‐linolenic acid inAnemone spp. seed lipids
Authors: Tsevegsüren Nansadyn , Aitzetmüller Kurt
Published: November 2006

γ‐Linolenic acid containing oils have been found in seed lipids of a number of plants, but are restricted to certain genera and families,e.g., the Boraginaceae. Some of these oils have found considerable interest for pharmaceutical and dietary use,e.g., borage oil and evening primrose oil in treatment of essential fatty acid and Δ6 desaturase deficiency. Our investigation of the seed lipids of certain Mongolian and other Ranunculaceae has now shown the presnce of unusual fatty acids, including considerable amounts (up to 20%) ofγ‐linolenic acid in certain species ofAnemone, whereas this acid was found to be absent in other species ofAnemone. A number of other unusual fatty acids are present inA. rivularis but have not yet been identified. The significance of the presence ofγ‐linolenic acid, a Δ6 acid, is discussed in relation to δ5 fatty acids that had been reported to occur in the same plant family.
Synthesis of ethyl arachidonate‐19,19,20,20‐d4 and ethyl dihomo‐γ‐linolenate‐19,19,20,20‐d4
Authors: Luthria Devanand L. , Sprecher Howard
Published: November 2006

Ethyl 5,8,11,14‐eicosatetraenoate‐19,19,20,20‐d4 and ethyl 8,11,14‐eicosatrienoate‐19,19,20,20‐d4 were synthesized by Grignard coupling of the methanesulfonyl ester of 2,5‐undecadiyn‐1‐ol‐10,10,11,11‐d4 with 5,8‐nonadiynoic acid and 8‐nonynoic acid, respectively. The coupled products upon Lindlar reduction, followed by the preparation of their ethyl esters, yielded deuteriated ethyl arachidonate and ethyl dihomo‐γ‐linolenate, which were completely characterized by13C and1H nuclear magnetic resonance and mass spectral analysis.
Low‐fat diets do not lower plasma cholesterol levels in healthy men compared to high‐fat diets with similar fatty acid composition at constant caloric intake
Authors: Nelson Gary J. , Schmidt Perla C. , Kelley Darshan S.
Published: November 2006

In most studies reporting the effects of high‐fat (HF) and low‐fat (LF) diets on human plasma fatty acids (FA) and lipoprotein levels, the design involved adding to the diet an oil that had an FA composition (FAC) very different from the FAC of the control diet. Thus, it is difficult to determine if simply reducing the fat content of the diet without changing the dietary FAC changes the tissue FAC or alters plasma lipid levels. In this study, we fed diets that contained either 22 or 39% of calories from fat, but had no differences in their FAC, for 50 d to a group (n=11) of healthy men (20–35 y). Thus, the polyunsaturated/saturated ratios (1.0) of the diets were identical as were the n−3/n−6 ratio and the monounsaturated‐to‐total fat ratios. The diets contained (wt% of total fat) approximately 28% saturated FA, 33% monounsaturatedcis‐FA, 6% monounsaturatedtrans‐FA, 22% n−6 polyunsaturated FA, and 7% n−3 polyunsaturated FA, and 4% other minor FA. The diets consisted of natural foods and were formulated to contain 16 en% protein, either 45 or 62 en% carbohydrate (CHO) and at least the recommended dailyallowance for all micronutrients. Both diets contained 360 mg of cholesterol per day. All subjects were given the HF diet for 20 d, and then six were placed on the LF and the other five remained on the HF diet for 50 d. The two groups were crossedover for the remaining 50 d of the study. The subjects' baseline total cholesterol level was 173 mg/dl, after 50 d on the HF diet it was 177 mg/dl and after 50 d on the LF diet, 173 mg/dl. The differences were not significant, and there were no significant changes in either the LDL or HDL cholesterol levels with either diet. Triglyceride levels, and consequently very low density lipoprotein levels, rose significantly on the LF, higher CHO diet compared to the levels found in the subjects on the HF diet (91.5 and 66.4 mg/dl respectively,P<0.002). The linoleic acid content of the plasma, platelets, and red blood cells was significantly (P<0.05) reduced in the LF diet compared to HF diet, without any obvious physiological effects. Hence, many earlier observations indicating reductions in plasma lipid levels when people are on LF diets may be due to changes in the FAC of the diet, not the reduction in fat calories.
Changes in linoleic acid metabolism and membrane fatty acids of LLC‐PK cells in culture induced by 5α‐cholestane‐3β, 5, 6β‐triol
Authors: Mahfouz M. , Smith T. , Kummerow F. A.
Published: November 2006

The aim of this study was to investigate the effect of the oxysterol 5α‐cholestane‐3β, 5, 6β‐triol (triol) on the metabolism of linoleic acid (18∶2n−6) to arachidonic acid (20∶4n−6) and on the cell membrane fatty acid composition. Porcine kidney cells were incubated in medium with or without 10 μg/mL of triol for 24 h, then incubated for 1, 6, or 12 h in a medium which contained 50 μM of either [14C]linoleic acid or unlabeled linoleic acid. The cellular uptake of [14C] linoleic acid was significantly higher in the triol‐treated cells than in control cells. After 1‐ and 6‐h incubations despite the increase of [14C]linoleic acid pool size in the triol‐treated cells, neither total n−6 polyunsaturated fatty acids (PUFA) metabolites nor arachidonic acid were increased in the triol‐treated cells as compared to the control cells, but trienoic acids accumulated to a greater extent in the triol‐treated cells. Therefore, the ratios of n−6 PUFA metabolites vs. pool size of linoleic acid and of tetraenoic acids vs. dienoic acids were significantly decreased in triol‐treated cells as compared to the control cells. The cellular fatty acid composition also showed that linoleic acid percentage was significantly increased while arachidonic acid percentage was significantly decreased in the triol‐treated cells, and that the accumulation of trienoic acids (18∶3n−6+20∶3n−6) observed from the [14C]linoleic acid experiment was due solely to increased 20∶3n−6 content. This latter finding indicates that a decrease of elongase activity by triol is unlikely. Our results also showed that the triol‐treated cells had a lower level of free cholesterol but higher levels of phospholipid and triol in their membranes, suggesting that triol displaced free cholesterol from the cell membrane.
Enzymatic hydrolysis of long‐chainN‐heterocyclic fatty esters
Authors: Jie Marcel S. F. Lie Ken , Syed‐Rahmatullah M. S. K.
Published: November 2006

Incubation of a 1‐pyrroline ester [viz. methyl 8‐(5‐hexyl‐1‐pyrroline‐2‐yl)octanoate,1] with bakers' yeast (Saccharomyces cerevisiae) gave the corresponding free fatty acid (1a, 52%). The C=N bond of the 1‐pyrroline was not reduced by the yeast. Complete hydrolysis of compound1 was successful using lipase ofCandida cylindracea (CCL) or Lipolase (Rhizomucor miehei) under stirred or ultrasound condition. Fatty esters containing a pyrrolidine [viz. methyl 8‐(cis/trans‐5‐hexyl‐pyrrolidine‐2‐) octanoate,2] orN‐methyl pyrrolidine [viz. methyl 8‐(cis‐5‐hexyl‐N‐methyl‐pyrrolidine‐2‐)octanoate,3] system in the alkyl chain were not hydrolyzed by either CCL or Lipolase, unless conducted in an ultrasonic bath. The hydrolytic activities of the enzymes appeared to be strongly affected by the stereochemistry of theN‐heterocyclic ring system. Chemical hydrolysis of compounds1–3 gave the corresponding fatty acidN‐HCl salts.
Chemiluminescence detection of mono‐, bis‐, and tris‐hydroperoxy triacylglycerols present in vegetable oils
Authors: Miyazawa Teruo , Kunika Hikoichiro , Fujimoto Kenshiro , Endo Yasushi , Kaneda Takashi
Published: November 2006

A reliable method was needed to analyze molecular species of oxidized vegetable oils. In order to accomplish this goal, mono‐, bis‐, and tris‐hydroperoxides (Mono‐OOH, Bis‐OOH, and Tris‐OOH, respectively) of triacylglycerols formed during autoxidation and photosensitized oxidation of oils were determined by reversed‐phase high‐performance liquid chromatography in combination with chemiluminescence detection (CL‐HPLC). Mono‐OOH was the major species (96% of total hydroperoxides) in trioleoylglycerol [peroxide value (PV) 0.16 meq/kg], and Bis‐OOH and Tris‐OOH showed prolonged accumulation with photooxidation. This profile was confirmed in photooxidation of trilinoleoylglycerol and trilinolenoylglycerol. Soybean oil (PV 6 meq/kg) contained Mono‐OOH oleoyl‐linoleoyl‐linoleoylglycerol as the main peroxidic molecular species (50% of total hydroperoxides). Mono‐OOH trilinoleoylglycerol was the principal species (61% of total hydroperoxides) in safflower oil (PV 5 meq/kg), and Mono‐OOH oleoyl‐oleoyl‐linoleoylglycerol was the representative species (66% of total hydroperoxides) in olive oil (PV 3 meq/kg). The CL‐HPLC method, which is specific for the detection of hydroperoxides, should prove useful in studies of triacylglycerol oxidation in foods and vegetable oils.
Biodiscrimination of α‐tocopherol stereoisomers during intestinal absorption
Authors: Kiyose Chikako , Muramatsu Riho , Fujiyama‐Fujiwara Yoko , Ueda Tadahiko , Igarashi Osamu
Published: November 2006

Synthetic α‐tocopherol (α‐Toc) contains equal amounts of eight different stereoisomers, and the four stereoisomers with the 2R configuration are generally more active than their correspoding 2S‐isomers. We investigated the biodiscrimination of α‐Toc stereoisomers during intestinal absorptionin situ andin vitro. Intestinal absorption of α‐Toc stereoisomers was examinedin situ in vitamin E‐deficient rats with cannulated thoracic ducts. We found that the ratios of α‐Toc stereoisomers in lymph of the all‐rac‐α‐Toc group were the same as the administered α‐Toc stereoisomers, and 2R‐isomers occupied approximately 50% of absorbed α‐Toc. The uptake of α‐Toc stereoisomers also was measured using Caco‐2 cells cultured on filter membranes. The concentration ofRRR‐α‐Toc in Caco‐2 cells was not significnatly different from that ofSRR‐α‐Toc. Therefore, the discrimination of α‐Toc stereoisomers does not occur during absorption in small intestine, suggesting the liver as a source for the biodiscrimination.
Dietary menhaden oil enhances mitomycin C antitumor activity toward human mammary carcinoma MX‐1
Authors: Shao Yu , Pardini Lani , Pardini Ronald S.
Published: November 2006

In the present study, we investigated the effects of high levels of dietary fish oil on the growth of MX‐1 human mammary carcinoma and its response to mitomycin C (MC) treatment in athymic mice. We found that high levels of dietary fish oil (20% menhaden oil+5% corn oil, w/w) compared to a control diet (5% corn oil, w/w) not only lowered the tumor growth rate, but also increased the tumor response to MC treatment. We also found that high levels of dietary fish oil significantly increased the activities of tumor xanthine oxidase and DT‐diaphorase, which are proposed to be involved in the bioreductive activation of MC. Since menhaden oil is highly unsaturated, its intake caused a significant increase in the degree of fatty acid unsaturation in tumor membrane phospholipids. This alteration in tumor membrane phospholipids made the tumor more susceptible to oxidative stress, as indicated by the increased levels of both endogenous lipid peroxidation and protein oxidation after feeding the host animals the menhaden oil diet. In addition, the tumor antioxidant enzyme activities, catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPOx), and glutathione S‐transferase peroxidase (GSTPx), were all significantly enhanced by feeding a diet high in fish oil. MC treatment caused further increases in tumor lipid peroxidation and protein oxidation, as well as in the activities of CAT, SOD, GPOx, and GSTPx, suggesting that MC causes oxidative stress in this tumor model which is exacerbated by feeding a diet high in menhaden oil. Thus, feeding a diet rich in menhaden oil decreased the growth of human mammary carcinoma MX‐1, increased its responsiveness to MC, and increased its susceptibility to endogenous and MC‐induced oxidative stress, and increased the tumor activities of two enzymes proposed to be involved in the bioactivation of MC, that is, DT‐diaphorase and xanthine oxidase. These findings support a role of these two enzymes in the bioactivating of MC and indicate that the type of dietary fat may be important in tumor response to therapy.
Phospholipid profiling of sediments using phosphorus‐31 nuclear magnetic resonance
Authors: Bardygula‐Nonn Lidia G. , Kaster Jerry L. , Glonek Thomas
Published: November 2006

A phosphorus‐31 nuclear magnetic resonance method has been developed for the determination of aquatic sediment phospholipid profiles that may be generally applied to all soils and deposits containing viable cellular material. A method of scrubbing chloroform/methanol extracts with potassium acid phosphate overcomes adverse signal broadening from the mineral component, permitting eleven sediment phospholipids to be determined at the quantitative level.
Inhibition of cholesterol synthesis and hepatic 3‐hydroxy‐3‐methylglutaryl‐CoA reductase in rats by simvastatin and pravastatin
Authors: Del Puppoo M. , Rauli S. , Kienle M. Galli
Published: November 2006

In this communication we attempt to provide one possible explanation for the observed differences regarding kinetics and distribution between simvastatin and pravastatin. Rats treated with simvastatin or pravastatin exhibited a reduction in the incorporation of [2‐14C]acetate into liver cholesterol and displayed lower plasma mevalonate levels as compared to control animals. Moreover, both the total and dephosphorylated 3‐hydroxy‐3‐methylglutaryl‐CoA (HMG‐CoA) reductase (EC 1.1.1.34) activities, particularly 1 h after treatment, were greatly reduced in liver microsomes obtained from simvastatin‐treated as compared to control rats. During the same time frame, these parameters were actually elevated with pravastatin treatment. It is known that HMG‐CoA reductase synthesis and activity increase following their competitive inhibition. Our results suggest that pravastatin, at 1 h following treatment, was no longer bound to the enzyme; however, it had entered the liver because its inhibitory effect on cholesterol synthesis was manifest at early times after administration. These data provide a plausible rationale for the earlier observation that activity of simvastatin persists longer in plasma than does that of pravastatin.
Leukotriene B4 stimulation of an early elevation of phosphatidic acid mass in human neutrophils
Authors: Tou Jen‐sie , Dola Thao
Published: November 2006

The signal transduction pathway of leukotriene B4 involves phospholipase D activation in cytochalsin B‐primed neutrophils, but leukotriene B4 stimulation of increased phosphatidic acid mass in neutrophils has not been demonstrated. Employing the NIH Image program, we have examined the effect of leukotriene B4 on phosphatidic acid mass in human neutrophils incubated with or without cytochalasin B. Our results show that 0.15 μM leukotriene B4 without cytochalasin B was capable of increasing phosphatidic acid mass in neutrophils by 2‐fold after 5 s, 2.5‐fold after 1 min, and 2‐fold after 5 min incubation. Leukotriene B3, leukotriene B4, and leukotriene B5 were equipotent stimuli for phosphatidic acid mass elevation. Leukotriene B4 induced phosphatidylethanol formation at the expense of phosphatidic acid in cells preincubated with 0.25–1% ethanol, indicating phospholipase D activation. Cytochalasin B enhanced leukotriene B4 stimulation of phosphatidic acid mass elevation and phosphatidylethanol formation. There were no measurable changes in 1,2‐diglyceride mass after 5 s, but a 1.7‐fold increase occurred after 1 min and declined thereafter. Leukotriene B4 stimulation of [3H]glycerol incorporation into phosphatidic acid, diglyceride and phosphatidylinositol was detectable after a 1‐min incubation, suggesting increasedde novo synthesis of these lipids. These results suggest that leukotriene B4 stimulation of phospholipase D activity contributes to part of the early increased phosphatidic acid mass and that combined actions of stimulated phospholipases C and D, andde novo phosphatidic acid synthesis contribute to the total increased phosphatidic acid mass.
The effect of two synthetic phospholipids on cell proliferation and phosphatidylcholine biosynthesis in Madin‐Darby canine kidney cells
Authors: Wieder Thomas , Haase Anne , Geilen Christoph C. , Orfanos Constantin E.
Published: November 2006

The concentration‐dependent effects of two different synthetic phospholipids on cell proliferation and phosphatidylcholine biosynthesis were compared in Madin‐Darby canine kidney (MDCK) cells. The alkyllysophospholipid 1‐O‐octadecyl‐2‐O‐methyl‐sn‐glycero‐3‐phosphocholine and the alkylphosphocholine, hexadecylphosphocholine, inhibited cell proliferation with half‐inhibitory concentrations (IC50) of 75 and 135 μmol/L, respectively. The agents also inhibited phosphatidylcholine biosynthesis in confluent and proliferating MDCK cells. The IC50 of 1‐O‐octadecyl‐2‐O‐methyl‐sn‐glycero‐3‐phosphocholine was 40 μmol/L in confluent cells and 20 μmol/L in proliferating cells, whereas the IC50 of hexadecylphosphocholine was higher in both experimental systems (67 μmol/L in confluent cells and 40 μmol/L in proliferating cells). Further experiments revealed that the effect of both agents on phosphatidylcholine biosynthesis was reversible and that the inhibition was mediated by translocation of the rate‐limiting enzyme of this pathway, CTP: phosphocholine cytidylyltransferase (EC 2.7.7.15), from membranes to the cytosol, where it is inactive. The present findings suggest that the inhibition of phosphatidylcholine biosynthesis by both synthetic phospholipids might be related, in part, to their antiproliferative effects.
Oxidized cholesterol modulates age‐related change in lipid metabolism in rats
Authors: Osada Kyoichi , Kodama Takehiro , Noda Satoshi , Yamada Koji , Sugano Michihiro
Published: November 2006

For three weeks, male Sprague‐Dawley rats at either four weeks (young) or eight months (adult) of age were pairfed one of the purified diets free of or containing either 0.2% of oxidized cholesterol mixture (cholesterol oxidation products) or 0.2% of cholesterol. Although the food intake was similar, dietary oxidized cholesterol lowered body weight gain in young rats, but did not increase relative liver weight, in contrast to the enlargement seen with dietary cholesterol. Oxidized cholesterol, compared to cholesterol, tended to reduce the activity of hepatic 3‐hydroxy‐3‐methylglutaryl CoA reductase and cholesterol 7α‐hydroxylase, particularly the latter in aged rats, and prevented the rise in the concentration of liver cholesterol at both ages. It also tended to increase the activity of hepatic δ6 desaturase, particularly in young rats. Moreover, oxidized cholesterol in relation to cholesterol influenced liver and serum lipid concentrations in different ways, and increased lipid peroxidation at both ages. The ratio of splenic CD4+/CD8+ T‐lymphocytes increased with age, but the influence of cholesterol and oxidized cholesterol was comparable. Thus, oxidized cholesterol may specifically disturb growth and age‐related changes in the lipid metabolism in rats.
Evidence that dietary arachidonic acid increases circulating triglycerides
Authors: Whelan Jay , Surette Marc E. , Li‐Stiles Bangyan , Bailey James W.
Published: November 2006

Male Syrian hamsters and male CD‐1 mice were fed diets supplemented with ethyl esters of oleic, linoleic, arachidonic, and eicosapentaenoic acids (1.1–1.5%, w/w) for 3–4 wk. Plasma and serum triglycerides were significantly higher in the arachidonic acid‐supplemented animals compared to those in the other supplementation groups. Changes in serum insulin and glucose levels did not appear to be related to the changes in circulating triglycerides observed in the arachidonic acid‐supplemented group. These data indicate that dietary arachidonic acid elevates circulating triglyceride levels compared to other unsaturated fatty acids in hamsters and mice by unknown mechanisms.
Dietary fish oils and long‐term malaria protection in mice
Authors: Fevang Per , Sääv Hjalmar , Høstmark Arne T.
Published: November 2006

Previous studies indicate a suppressive influence of fish oils on rodent malaria. The present work was carried out to study (i) the dose‐effect relation between dietary fish oils and lethality of primary malaria infection in mice; (iii) the modifying influence of vitamin E; and (iii) the effect of previous fish oil feeding on parasitemia and lethality of a rechallenge infection. For two or four weeks, groups of weanling male mice were fed a standard laboratory diet or one of eight purified diets containing various amounts of fish oil (providing 6–21% of energy). The diets were prepared with and without vitamin E. After the two‐or four‐week feeding period, the mice were injected intraperitoneally withPlasmodium yoelii yoelii‐infected erythrocytes. Six months after the primary infection (four months after discontinuing fish oil feeding), the surviving mice were again injected intraperitoneally with parasitized red blood cells (or even better—erythrocytes, erythrocytes are used elsewhere). Primary malaria infection was lethal in mice fed standard diet alone or with fish oil and vitamin E added. In contrast, feeding a fish oil‐based diet without vitamin E improved survival to at least 70% if the mice had been fed these diets for four weeks. Protection against malaria did not seem to be related to the fish oil dose used. Regardless of the previous fish oil dose, all the mice surviving the primary infection survived the rechallenge infection with low parasitaemias. The results suggest that the prooxidant nature of highly unsaturated fatty acids in fish oils may beneficially influence malaria infection, and may also increase the resistance against reinfection for some time after discontinuing fish oil intake.
Detection of [U‐13C]eicosapentaenoic acid in rat liver lipids using13C nuclear magnetic resonance spectroscopy
Authors: Cunnane S. C. , McDonagh R. J. , Narayan S. , Kyle D. J.
Published: November 2006

Fatty acid carbons are well‐resolved in13C nuclear magnetic resonance (NMR) spectra of lipid extracts, but application of this methodology to the metabolism of13C‐labelled fatty acids has not yet been reported. In the present study,13C NMR was used to monitor the presence of 98% [U‐13C]eicosapentaenoic acid (EPA) in liver and carcass lipids 24 h after it had been injected into the stomach of a rat. Natural abundance13C NMR spectra of liver total fatty acid extracts were obtained from four control rats for comparison. At 24 h post‐injection, quantitative high resolution13C NMR showed13C enrichment in liver fatty acid extracts was present mainly at olefinic and at the n−1 to n−4 carbons, but13C signal intensities for C−1 to C−4 of [U‐13C]EPA were markedly reduced or absent. Small13C resonances, possibly indicative of some13C incorporation into docosahexaenoic acid and saturated or monounsaturated fatty acids, were present in spectra of liver fatty acids. Liver and carcass fatty acid composition was similar in both the controls and the EPA‐injected rat, suggesting little accumulation of the injected [U‐13C]EPA after 24 h. We conclude that the carbon‐specific data provided by13C NMR of lipid extracts may be useful in monitoring the fate of individual carbons during tracer studies using13C‐labelled fatty acids.
Positional distribution on n−3 fatty acids in triacylglycerols from rat adipose tissue during fish oil feeding
Authors: Leray Claude , Raclot Thierry , Groscolas René
Published: November 2006

The present study was designed to investigate the metabolism of the n−3 olyunsaturated fatty acids (PUFA) in adipose tissue and its dependence upon dietary factors. Changes in the positional distribution of the fatty acids in triacylglycerols from retroperitoneal adipose tissue were studied as a function of time on rats fed for 4 wk a diet enriched with fish oil. The stereospecific analysis of triacylglycerols was based on random formation ofrac‐1,2‐diacylglycerols by Grignard degradation. This was followed by synthesis ofrac‐phosphatidic acids and treatment with phospholipase A2. In the triacylglycerols of the fish oil diet, 57% of the total n−3 fatty acids were in position 3,i.e., two‐thirds of 22∶5n−3 and 22∶5n−3 were esterified insn‐3 position, whereas 22∶6n−3 was equally distributed in positions 2 and 3. After 4 wk of feeding fish oil, the fatty acid composition of adipose tissue triacylglycerols reached a steady state. Half of the n−3 fatty acids were found in position 3, namely 75% of 22∶5n−3, 50% of 20∶5n−3 and 18∶4n−3 and 45% of 22∶6n−3, the latter being equally distributed in positions 2 and 3. This pattern of distribution resembled that found in triacylglycerols of the fish oil diet, except for a higher proportion of 20∶5n−3 in adipose tissue in position 1 at the expense of position 3. Throughout the 4‐wk period of fish oil feeding, the distribution pattern of minor n−3 fatty acids (18∶4n−3 and 22∶5n−3) in adipose tissue triacylglycerols remained unchanged. On the other hand, at the onset of fish oil feeding, 20∶5n−3 and 22∶6n−3 became concentrated in position 3, but thereafter 20∶5n−3 was progressively incorporated into position 1 and 22∶6n−3 into position 2. We thus conclude that n−3 fatty acids are differentially esterified in triacylglycerols of white adipose tissue. Despite the complex sequence of hydrolysis and acylation steps involved, the positional distribution of n−3 fatty acids was found to be similar in both the fish oil diet and the stored fat, in contrast to what was observed for nonessential fatty acids.
Effect of Δ9‐tetrahydrocannabinol and merthiolate on acyltransferase activities in guinea pig liver microsomesand merthiolate on acyltransferase activities in guinea pig liver microsomes
Authors: Badiani Ketan , Lu Xiaoli , Arthur Gilbert
Published: November 2006

Δ9‐tetrahydrocannabinol (THC) and merthiolate have been utilized as lysophospholipid acyltransferase inhibitors in metabolic studies. However, their effects on acyltransferases other than lysophosphatidylcholine:acyl‐CoA acyltransferase (LPCAT) are not known. We have therefore investigated the effectiveness of THC and merthiolate in inhibiting the acylation of lysophosphatidylcholine, lysophosphatidylethanolamine, lysophosphatidylserine, lysophosphatidylinositol (LPI) and lysophosphatidic acid (LPA) in guinea pig liver microsomes using oleoyl‐CoA and arachidonoyl‐CoA as acyl donors. THC inhibited LPCAT and lysophosphatidylethanolamine: acyl‐CoA acyltransferase (LPEAT) by 40–50%, but had no effect or only slightly increased the activities of the other acyltransferases when assayed with oleoyl‐CoA as the acyl donor. The results obtained with arachidonoyl‐CoA were similar to those with oleoyl‐CoA, with the exception of a 40% inhibition of lysophosphatidylserine:acyl‐CoA acyltransferase (LPSAT) at concentrations of 50 μM or higher. At similar concentrations, merthiolate was more effective than THC in inhibiting the acyltransferases examined. Selective effects on the acyltransferases were observed at low concentrations of merthiolate (20 μM or less). Thus, LPCAT was most susceptible, followed by LPI acyltransferases, LPSAT, LPEAT and lysophosphatidic acid:acyl‐CoA acyltransferases (LPAAT). The presence of LPA did not affect the inhibition of LPCAT by merthiolate. Thus the resilience of LPAAT to merthiolate inhibition was not due to chelation of the compound by the acidic lysolipid. Thiol reagents includingN‐ethylmaleiamide, 5,5′‐dithio‐bis‐nitrobenzoic acid, iodoacetate, β‐mercaptoethanol and dithiothreitol had little or no effect on the acyltransferases relative to equimolar concentrations of merthiolate. The above results indicate that merthiolate is a much more effective inhibitor of lysophospholipid:acyl‐CoA acyltransferases than is THC, and that the selectivity exhibited by merthiolate may be due to direct and specific interaction with the acyltransferases.
Cholesterol gallstone induction in hamsters reflects strain differences in plasma lipoproteins and bile acid profiles
Authors: Trautwein Eike A. , Liang Jinsheng , Hayes K. C.
Published: November 2006

Because different strains of hamsters vary in their susceptibility to gallstones, the relationship between plasma lipoproteins, hepatic cholesterol, bile lipids and bile acid profile was examined during gallstone induction in strains of male Syrian hamsters from Charles River Lakeview (CHR), Biobreeder F1B (BIO) and Harlan Sprague‐Dawley (HAR). Gallstones were induced by feeding a purified diet containing 0.4 or 0.8% cholesterol for 5 wk. Basal plasma total cholesterol was similar, but the hypercholesterolemia induced by dietary challenge was significantly lower in CHR than in HAR and BIO hamsters. Cholesterol‐fed CHR hamsters transported cholesterol mainly in HDL (47%), whereas VLDL‐C+IDL‐C predominated in BIO and HAR hamsters, and their HDL transported only 28 and 38%, respectively. HAR hamsters accumulated the most hepatic cholesterol, revealed the highest cholate/cheno ratio, the lowest glycine/taurine ratio and hydrophobicity index. HAR also developed the fewest cholesterol gallstones (23%), while 64% of CHR and 58% of BIO hamsters had cholesterol gallstones and 34% of BIO hamsters developed pigment stones. Doubling dietary cholesterol from 0.4 to 0.8% doubled the incidence of cholesterol gallstones but exerted minimal impact on other parameters compared to strain differences. Thus, different strains of hamsters vary considerably with respect to biliary cholesterol, bile acid profile and formation of cholesterol gallstones associated with differences in plasma lipoprotein profiles.
Hydrolysis of fish oils containing polymers of triacylglycerols by pancreatic lipasein vitro
Authors: Henderson R. James , Burkow Ivan C. , Millar Rose Mary
Published: November 2006

Fish oils containing different levels of polymers of triacylglycerols formed during autoxidation were incubated with pancreatic lipase to establish whether these polymers are substrates for lipase hydrolysis. With oils containing low amounts (less than 4%) of triacylglycerol polymers as substrates, both triacylglycerols and polymers of triacylglycerols were almost completely hydrolyzed, and fatty acid monomers and monoacylglycerols were the major lipid products. Under the same incubation conditions, some triacylglycerols remained intact when highly oxidized oils containing 20 or 30% triacylglycerol polymers were the substrate. The fatty acid composition of these residual triacylglycerols was almost identical to that of triacylglycerols present at the start of the assay. When fish oil containing 30% triacylglycerol polymers was incubated with the lipase, the component triacylglycerols and polymers of triacylglycerols were hydrolyzed at similar rates, and fatty acid dimers were detected as a product. It is concluded that the high molecular weight polymers of triacylglycerols present in oxidized fish oils can be hydrolyzed by pancreatic lipasein vitro.
Stearidonic acid, an inhibitor of the 5‐lipoxygenase pathway. A comparison with timnodonic and dihomogammalinolenic acid
Authors: Guichardant Michel , Traitler Helmut , Spielmann Danièle , Sprecher Howard , Finot Paul‐André
Published: November 2006

Leukotrienes have been shown to play an important role as mediators in various disease processes, including asthma and inflammation; thus, their synthesis is tightly regulated. The major precursor of leukotrienes is arachidonic acid (20∶4n−6). Fatty acids which are structurally similar to 20∶4n−6, such as eicosatrienoic acid (20∶3n−6; dihomogammalinolenic acid) and eicosapentaenoic acid (20∶5n−3; timnodonic acid) have been found to inhibit leukotriene biosynthesis. Because of the structural similarity of octadecatetraenoic acid (18∶4n−3; stearidonic acid) with 20∶4n−6, the present study was undertaken to determine whether stearidonic acid also exerts an inhibitory effect on the 5‐lipoxygenase pathway. Human leukocytes were incubated with 18∶4n−3 (20 μM or 10 μM), 20∶5n−3 (20 μM) or 20∶3n−6 (20 μM) and subsequently stimulated with 1 μM ionophore A23187 and 20∶4n−6 (20 μM or 10 μM). The 5‐lipoxygenase products were then measured by high‐performance liquid chromatography. Leukotriene synthesis was reduced by 50% with 20 μM 18∶4n−3 and by 35% with 10 μM 18∶4n−3. Formation of 5S,12S‐di‐hydroxy‐eicosatetraenoic acid and of 5‐hydroxy‐eicosatetraenoic acid was decreased by 25% with 20 μM 18∶4n−3 and by 3% with 10 μM 18∶4n−3. The inhibition observed with 20 μM 18∶4n−3 appeared to be of the same order as that observed with 20 μM 20∶5n−3; the inhibition observed with 18∶4n−3 was shown to be dosedependent. The inhibition produced by 20 μM 20∶3n−6 was greater than that observed with either 20 μM 18∶4n−3 or with 20 μM 20∶5n−3. The results suggest that stearidonic acid, which is found, for example, in blackcurrant seed oil (which also contains the 20∶3n−6 precursor), may play a role in suppressing inflammation.
O‐alkyl diolO‐,S‐ andSe‐phosphoroamidates of DL‐α‐tocopherol and their dimethylaminoalkyl derivatives as diester and triester models of phospholipids
Authors: Stamatov Stephan D. , Gronowitz Salo
Published: November 2006

Hexamethyltriamide of phosphorous acid, activated by addition of iodine at an optimal molar ratio of 1.05∶0.05, was used as a phosphorylating reagent to synthesize 1‐hexadecyloxyethyl‐2‐O‐, 1‐hexadecyloxypropyl‐3‐O‐, and 1‐hexadecyloxybutyl‐4‐O‐(DL‐α‐tocopheryl‐6‐O)‐(N,N‐dimethylamido)selenophosphate,‐thiophosphate and‐phosphate derivatives, and some of their 2‐dimethyl‐aminoethyl‐1‐O‐, and 3‐dimethylaminopropyl‐1‐O‐triester analogues in a “one‐pot procedure” in overall yields of 69–87%. Activation of the reaction with an equimolar mixture of imidazole and carbon disulfide at the triester formation step permits selective phosphorylation at room temperature. The compounds synthesized represent new diester and triester models containing alkyl ether diolphospholipid structures.
Use of acetyl chloride/methanol for assumed selective methylation of plasma nonesterified fatty acids results in significant methylation of esterified fatty acids
Authors: Hallaq Youssef , Becker Thomas C. , Manno Catherine S. , Laposata Michael
Published: November 2006

The albumin‐bound nonesterified fatty acid pool in plasma, which represents a very small percentage of total plasma fatty acids, has previously been quantitated by a variety of methods. In the present study we determined that the nonesterified fatty acid concentrations in the plasma, quantitated by a popular method using acetyl chloride and methanol which is reported to be specific for methylation of nonesterified fatty acids in the presence of esterified fatty acids (i.e., without prior isolation of the plasma non‐esterified fatty acids), were significantly overestimated due to cleavage and methylation of esterified fatty acids. Quantitation of the contaminating fatty acid from the esterified pool demonstrated that the amount of fatty acid cleaved from the esterified pool was enough to exceed the entire mass of nonesterified fatty acids. As an established method for comparison, we isolated nonesterified fatty acids from the plasma by thin‐layer chromatography prior to methylation, using a number of simple precautions to limit oxidation. By performing all thin‐layer chromatography steps in an atmosphere of nitrogen and by including fatty acid standards in the plasma with 0,1, 2 or 4 double bounds, we were able to accurately and reproducibly determine the concentration of nonesterified fatty acids in the plasma, including arachidonate. We demonstrated that no oxidation occurred in the thin‐layer chromatographic isolation of homonesterified fatty acids and that the coefficients of variation for repeat measurements of the same sample were <11% using our reference method. Our data indicate that the use of acetyl chloride and methanol for assumed selective methylation of plasma nonesterified fatty acids results in significant methylation of esterified fatty acids.
Profiling of arachidonic acid metabolites in rabbit platelets by radio gas chromatography
Authors: Akira Kazuki , Nakamura Tatsuji , Shinohara Yoshihiko , Baba Shigeo
Published: November 2006

A method for profiling arachidonic acid metabolites by radio gas chromatography (GC) is described. The incubation mixture of rabbit platelets with [14C]arachidonic acid was purified on a Sep‐Pak C18 cartridge and derivatized with diazomethane,O‐methylhydroxylamine and dimethylisopropylsilylimidazole. The recovery of total14C‐radioactivity was 93.1±7.2%. Loss of radioactivity during derivatization was negligible. Baseline separations for [14C]arachidonic acid and its metabolites were obtained in a single run within 45 min by GC using a synchronized accumulating radioisotope detector (GC/SARD). The recovery of radioactivity from the GC column was virtually 100%. The chemical structures of the metabolites were confirmed by GC/mass spectrometry; peaks of arachidonic acid metabolites were assigned by comparison of the methylene unit values with those of radioactive peaks in GC/SARD analyses. The intra‐assay coefficients of variation in GC/SARD analyses were less than 10%. The method was used to map the profile of arachidonic acid metabolites formed by rabbit platelets in the presence of indomethacin, baicalein or glutathione.
Effect of nonionic detergents on lipoxygenase catalysis
Authors: Schilstra Maria J. , Veldink Gerrit A. , Vliegenthart Johannes F. G.
Published: November 2006

In many studies on lipoxygenase catalysis, nonionic detergents are used to obtain an optically transparent solution of the fatty acid substrate. In order to resolve some controversies that exist with regard to the interpretation of kinetic data obtained with solutions containing nonionic detergents, a systematic investigation was undertaken into the effects of Lubrol, Tween‐20 and Triton X‐100 (0–0.8 g/L) on the kinetics of linoleate (2.5–110 μM) dioxygenation, catalyzed by lipoxygenase‐1 or lipoxygenase‐2 from soybean, at pH 9 or 10, at 25°C. Under most conditions, it was found that the detergents slowed down the reaction. However, at high linoleate concentrations, where substrate inhibition of lipoxygenase is significant, small amounts of detergent increased the dioxygenation rate. In a quantitative analysis of the results, a kinetic model in which the incorporation of linoleate in the detergent micelles is formulated as a simple reversible equilibrium, and in which both lipoxygenase‐1 and‐2 interact with free linoleate, but not with linoleate incorporated in the micelles, appeared to be sufficient to predict experimental results over a wide range of experimental conditions. According to this model, the changes in the dioxygenation kinetics caused by the presence of nonionic detergents are similar (but not equal) to those caused by competitive inhibitors. The conclusions that monomeric, nonmicellar linoleate is the preferred substrate for lipoxygenase and that the observed inhibition and stimulation are solely due to changes in the effective linoleate concentration strongly corroborate the earlier observations by Galpin and Allen [Biochim. Biophys. Acta 488 (1977), 392–401].
Effect of n−3 fatty acid‐rich fish oil supplementation on the oxidation of low density lipoproteins
Authors: Frankel E. N. , Parks E. J. , Xu R. , Schneeman B. O. , Davis P. A. , German J. B.
Published: November 2006

This study was aimed at determining the effect of fish oil supplementation on copper‐catalyzed oxidation of low density lipoproteins (LDL) from nine hypertriglyceridemic human subjects. A rapid headspace gas chromatographic method was used to measure the volatile oxidation products from LDL. Propanal and hexanal were the major volatile products formed in the oxidation of n−3 and n−6 polyunsaturated fatty acids (PUFA), respectively. Fish oil supplementation resulted in a significant increase in propanal formation from 3.7 to 13.4 nmol/mL LDL (P<0.01); it also resulted in small decreases in pentanal formation from 14.7 to 11.4 nmol/mL LDL and in hexanal formation from 138 to 108 nmol/mL LDL (P<0.05). The changes in peroxidation products paralleled the changes in LDL composition, which showed a significant increase in n−3 PUFA from 3.2 to 14.6% (P<0.01) and a decrease in n−6 PUFA from 43.7 to 35.0% (P<0.05). Propanal formation was highly and significantly correlated with n−3 PUFA content (r=0.950,P<0.001). Since total volatiles remained unchanged, this indicated that the two groups of LDL samples did not differ in overall oxidative susceptibility. Although fish oil intake did not alter the oxidative susceptibility of LDL, the chemically modified LDL particles generated a distinct pattern of volatile oxidation products that reflected changes in their fatty acid composition.