bluuebunny/crossref_metadata_2025 huggingface dataset:
Relationships between the fatty acid composition of muscle and erythrocyte membrane phospholipid in young children and the effect of type of infant feeding
Authors: Baur Louise A. , O’Connor Janice , Pan David A. , Wu Ben J. , O’Connor Marcus J. , Storlien Leonard H.
Published: November 2006

Muscle membrane fatty acid (FA) composition is linked to insulin action. The aims of this study were to compare the FA composition of muscle and erythrocyte membrane phospholipid in young children; to investigate the effect of diet on these lipid compositions; and to investigate differential incorporation of FA into muscle, erythrocyte and adipose tissue membrane phospholipid, and adipose tissue triglyceride. Skeletal muscle biopsies and fasting blood samples were taken from 61 normally nourished children (15 males and 16 females), less than 2 yr old (means ±SE, 0.80±0.06 yr), undergoing elective surgery. Adipose tissue samples were taken from 15 children. There were significant positive correlations between muscle and erythrocyte docosahexaenoic acid (DHA) (r=0.44, P<0.0001), total n−3 polyunsaturated fatty acids (PUFA) (r=0.39, P=0.002), and the n−6/n−3 PUFA ratio (r=0.39, P=0.002). Adipose tissue triglyceride had lower levels of long‐chain PUFA, especially DHA, than muscle and erythrocytes (0.46±0.18% vs. 2.44±0.26% and 3.17±0.27%). Breast‐fed infants had higher levels of DHA than an age‐matched group of formulafed infants in both muscle (3.91±0.21% vs. 1.94±0.18%) and erythrocytes (3.81±0.10% vs. 2.65±0.23%). The results of this study show that (i) erythrocyte FA composition is a reasonable index of muscle DHA, total n−3 PUFA, and the n−6/n−3 PUFA ratio; (ii) breast feeding has a potent effect on the FA composition of all these tissues; and (iii) there is a wide range in long‐chain PUFA levels in muscle, erythrocytes, and adipose tissue.
Effects of conjugated linoleic acid isomers on lipid‐metabolizing enzymes in male rats
Authors: Martin Jean‐Charles , Grégoire Stéphane , Siess Marie‐Hélène , Genty Martine , Chardigny Jean‐Michel , Berdeaux Olivier , Juaneda Pierre , Sébédio Jean‐Louis
Published: November 2006

Male weanling Wistar rats (n=15), weighing 200–220 g, were allocated for 6 wk to diets containing 1% (by weight) of conjugated linoleic acid (CLA), either as the 9c,11t‐isomer, the 10t,12c‐isomer, or as a mixture containing 45% of each of these isomers. The five rats of the control group received 1% of oleic acid instead. Selected enzyme activities were determined in different tissues after cellular subfractionation. None of the CLA‐diet induced a hepatic peroxisome‐proliferation response, as evidenced by a lack of change in the activity of some characteristic enzymes [i.e., acyl‐CoA oxidase, CYP4A1, but also carnitine palmitoyltransferase‐I (CPT‐I)] or enzyme affected by peroxisome‐proliferators (glutathione S‐transferase). In addition to the liver, the activity of the rate‐limiting β‐oxidation enzyme in mitochondria, CPT‐I, did not change either in skeletal muscle or in heart. Conversely, its activity increased more than 30% in the control value in epididymal adipose tissue of the animals fed the CLA‐diets containing the 10t,12c‐isomer. Conversely, the activity of phosphatidate phosphohydrolase, a rate‐limiting enzyme in glycerolipid neosynthesis, remained unchanged in adipose tissue. Kinetic studies conducted on hepatic CPT‐I and peroxisomal acyl‐CoA oxidase with CoA derivatives predicted a different channeling of CLA isomers through the mitochondrial or the peroxisomal oxidation pathways. In conclusion, the 10t,12c‐CLA isomer seems to be more efficiently utilized by the cells than its 9c,11t homolog, though the Wistar rat species appeared to be poorly responsive to CLA diets for the effects measured.
Apolipoprotein E polymorphism: Automated determination of apolipoprotein E2, E3, and E4 isoforms
Authors: Wiebe Claudia , Holzem Guido , Wielckens Klaus , Klingler Karl Rolf
Published: November 2006

Apolipoprotein E (apo E) plays an essential role in lipoprotein metabolism, where it is involved in the clearance of chylomicrons and very low density lipoproteins. Apart from some rate variants, apo E exists in three common isoforms (E2, E3, and E4). The different isoforms have not only been associated with different plasma lipid levels but have also been correlated with certain pathological conditions, such as lipid disorders (dysbetalipoproteinemia, hypercholesterolemia), cardiovascular diseases, and Alzheimer's disease. Here we describe a rapid, automated test for the determination of the most frequent polymorphisms (E2, E3, and E4). This polymerase chain reaction‐based test allows the reliable discrimination of all six genotypes. The assay has been developed especially for the nonspecialized routine clinical laboratory by employing an analyzer and chemistry often present in this type of laboratory. Because of its low costs and easy handling, the assay can be performed on a daily basis.
Cloning and characterization of the Dictyostelium discoideum cycloartenol synthase cDNA
Authors: Godzina Sharotka M. , Lovato Martha A. , Meyer Michelle M. , Foster Kimberly A. , Wilson William K. , Gu Wei , de Hostos Eugenio L. , Matsuda Seiichi P. T.
Published: November 2006

Cycloartenol synthase converts oxidosqualene to cycloartenol, the first carbocyclic intermediate en route to sterols in plants and many protists. Presented here is the first cycloartenol synthase gene identified from a protist, the cellular slime mold Dictyostelium discoideum. The cDNA encodes an 81‐kDa predicted protein 50–52% identical to known higher plant cycloartenol synthases and 40–49% identical to known lanosterol synthases from fungi and mammals. The encoded protein expressed in transgenic Saccharomyces cerevisiae converted synthetic oxidosqualene to cycloartenol in vitro. This product was characterized by 1H and 13C nuclear magnetic resonance and gas chromatography‐mass spectrometry. The predicted protein sequence diverges sufficiently from the known cycloartenol synthase sequences to dramatically reduce the number of residues that are candidates for the catalytic difference between cycloartenol and lanosterol formation.
Cloning and sequencing of the Candida albicans C‐4 sterol methyl oxidase gene (ERG25) and expression of an ERG25 conditional lethal mutation in Saccharomyces cerevisiae
Authors: Kennedy Matthew A. , Johnson Theresa A. , Lees N. Douglas , Barbuch Robert , Eckstein James A. , Bard Martin
Published: November 2006

The ERG25 gene encoding the Candida albicans C‐4 sterol methyl oxidase was cloned and sequenced by complementing a Saccharomyces cerevisiae erg25 mutant with a C. albicans genomic library. The Erg25p is comprised of 308 amino acids and shows 65 and 38% homology to the enzymes from S. cerevisiae and Homo sapiens, respectively. The protein contains three histidine clusters common to nonheme iron‐binding enzymes and an endoplasmic reticulum retrieval signal as do the proteins from S. cerevisiae and humans. A temperature‐sensitive (ts) conditional lethal mutation of the C. albicans ERG25 was isolated and expressed in S. cerevisiae. Sequence analysis of the ts mutant indicated an amino acid substitution within the region of the protein encompassed by the histidine clusters involved in iron binding. Results indicate that plasmid‐borne conditional lethal mutants of target genes have potential use in the rescue of Candida mutations in genes that are essential for viability.
Plant sterol‐C24‐methyl transferases: Different profiles of tobacco transformed with SMT1 or SMT2
Authors: Schaeffer Aurélie , Bouvier‐Navé Pierrette , Benveniste Pierre , Schaller Hubert
Published: November 2006

Higher plant cells contain a mixture of 24‐desmethyl, 24‐methyl(ene), and 24‐ethyl(idene) sterols in given proportions according to species but also to cell type. As a first step to investigate the function of such sterol compositions in the physiology of a plant, we have illustrated in the present work the coexistence of two distinct (S)‐adenosyl‐l‐methionine sterol‐C24‐methyltransferases (SMT) in transgenic Nicotiana tabacum L. Indeed, modulation of the expression of the tobacco gene SMT1‐1, which encodes a cycloartenol‐C24‐methyltransferase, results in variations of the proportion of cycloartenol and a concomitant effect on the proportion of 24‐ethyl sterols. Overexpression in tobacco of the Arabidopsis thaliana (L.) Heynh. gene SMT2‐1 which encodes a 24‐methylene lophenol‐C241‐methyltransferase, results in a dramatic modification of the ratio of 24‐methyl cholesterol to sitosterol associated with a reduced growth, a topic discussed in the present work.
Biosynthesis of sterols and ecdysteroids in Ajuga hairy roots
Authors: Fujimoto Yoshinori , Ohyama Kiyoshi , Nomura Keiko , Hyodo Ryo , Takahashi Kyoko , Yamada Junko , Morisaki Masuo
Published: November 2006

Hairy roots of Ajuga reptans var. atropurpurea produce clerosterol, 22‐dehydroclerosterol, and cholesterol as sterol constituents, and 20‐hydroxyecdysone, cyasterone, isocyasterone, and 29‐norcyasterone as ecdysteroid constituents. To better understand the biosynthesis of these steroidal compounds, we carried out feeding studies of variously 2H‐ and 13C‐labeled sterol substrates with Ajuga hairy roots. In this article, we review our studies in this field. Feeding of labeled desmosterols, 24‐methylenecholesterol, and 13C2‐acetate established the mechanism of the biosynthesis of the two C29‐sterols and a newly accumulated codisterol, including the metabolic correlation of C‐26 and C‐27 methyl groups. In Ajuga hairy roots, 3α‐, 4α‐, and 4β‐hydrogens of cholesterol were all retained at their original positions after conversion into 20‐hydroxyecdysone, in contrast to the observations in a fern and an insect. Furthermore, the origin of 5β‐H of 20‐hydroxyecdysone was found to be C‐6 hydrogen of cholesterol exclusively, which is inconsistent with the results in the fern and the insect. These data strongly support the intermediacy of 7‐dehydrocholesterol 5α,6α‐epoxide. Moreover, 7‐dehydrocholesterol, 3β‐hydroxy‐5β‐cholest‐7‐en‐6‐one (5β‐ketol), and 3β,14α‐dihydroxy‐5β‐cholest‐7‐en‐6‐one (5β‐ketodiol) were converted into 20‐hydroxyecdysone. Thus, the pathway cholesterol→7‐dehydrocholesterol→7‐dehydrocholesterol 5α,6α‐epoxide→5β‐ketol→5β‐ketodiol is proposed for the early stages of 20‐hydroxyecdysone biosynthesis. 3β‐Hydroxy‐5β‐cholestan‐6‐one was also incorporated into 20‐hydroxyecdysone, suggesting that the introduction of a 7‐ene function is not necessarily next to cholesterol. C‐25 Hydroxylation during 20‐hydroxyecdysone biosynthesis was found to proceed with ca. 70% retention and 30% inversion. Finally, clerosterol was shown to be a precursor of cyasterone and isocyasterone.
The effects of dehydroepiandrosterone on carcinogenesis, obesity, the immune system, and aging
Authors: Williams John R.
Published: November 2006

With the passage of the U.S. Dietary Supplement Health and Education Act of 1994, dehydroepiandrosterone (DHEA, 5‐androsten‐3β‐ol‐17‐one) has become widely available, and a large and growing market has developed for this “fountain of youth”. DHEA has been shown to have significant beneficial effects in animals, which may lead to clinical uses in man. Historically, the U.S. Food and Drug Administration removed DHEA from the over‐the‐counter market in 1985 because there was no support for the health claims that were made for this product. Almost all of the biological data was on animals and there was a lack of demonstrated efficacy in humans. Recently there have been a number of small clinical trials in humans but the results have not been as positive as in the animal tests. This review will be restricted to the effects of DHEA on carcinogenesis, obesity, the immune system, and aging. Four hypotheses have been proposed to explain the underlying biochemical mechanism(s) by which DHEA exerts its beneficial properties. The first is based on the inhibitory effect of DHEA on mammalian glucose‐6‐phosphate dehydrogenase. This mechanism can explain the antiinitiation and antipromotion steps in some cases of carcinogenesis. The second biochemical mechanism involves the induction of peroxisomes and peroxisome‐associated enzymes. The third explanation is that DHEA works in a similar fashion to the known anticarcinogenic action of food restriction. An antiglucocorticoid mechanism has also been suggested. A hypothesis for the increase followed by the decrease in the levels of DHEA with age is proposed. A number of new synthetic DHEA analogs have been synthesized and tested. They offer the best hope for the development of a clinically useful drug based on the properties of DHEA.
Alterations in 3‐hydroxy‐3‐methylglutaryl‐CoA reductase mRNA concentration in cultured chick aortic smooth muscle cells
Authors: Carazo Angel , Alejandre M José , Suarez M Dolores , Linares Ana
Published: November 2006

We observed and compared alterations in 3‐hydroxy‐3‐methylglutaryl (HMG)‐CoA reductase at the transcriptional level in unsynchronized, three‐passage cultures of smooth‐muscle cells from the aorta of chicks fed on a control diet (C‐SMC) and those of chicks fed on a similar diet plus cholesterol (Ch‐SMC). Alterations in reductase mRNA concentrations in senescent cultures were much lower. We used a modification of the competitive (c) reverse transcription polymerase chain reaction method, using a Thermus thermophilus DNA polymerase (Tth pol) to quantify the very scarce species of HMG‐CoA reductase mRNA in samples of cytoplasmic SMC mRNA. We cloned and sequenced a 199 bp cDNA fragment of chicken HMG‐CoA reductase, which encoded a region of 66 amino acids belonging to the catalytic domain of the enzyme. HMG‐CoA reductase mRNA concentrations from young C‐SMC cultures rose 3.89‐fold 4 h after the change of medium and returned to base levels between 8 to 12 h afterward. Concentrations in Ch‐SMC cultures increased less (2.36‐fold) 8 h after the change to fresh medium. Increases in reductase mRNA in senescent cultures of Ch‐SMC and C‐SMC measured under similar conditions were only 1.28‐ and 1.39‐fold, respectively.
Cholesterol vehicle in experimental atherosclerosis. 23. Effects of specific synthetic triglycerides
Authors: Kritchevsky David , Tepper Shirley A. , Chen Shirley C. , Meijer Gert W. , Krauss Ronald M.
Published: November 2006

Earlier work has shown that increasing concentration of palmitic acid at the sn‐2 position of a fat enhances the atherogenic properties of that fat. This effect has been observed with lard, tallow, cottonseed oil, and palm oil. In the experiment reported here, we have studied the atherogenic effects of four synthetic fats fed to rabbits as 58% (w/w) of the total fat (15%) (w/w) of a semipurified diet containing 0.05% cholesterol. The fats being tested were: 1,3‐stearoyl‐2‐oleoylglycerol (SOS); 1,2‐stearoyl‐3‐oleoylglycerol (SSO); 1,3‐palmitoyl‐2‐oleoylglycerol (POP); and 1,2‐palmitoyl‐3‐oleoylglycerol (PPO). After 20 wk on diet there were no differences among the groups in weight gain, liver weight, serum, or liver lipids. These data are consistent with our previous findings. There were significant differences in atherosclerosis. The most severe atherosclerosis was observed in group PPO and the least in groups SSO and POP. Severity of atherosclerosis was graded visually on a 0–4 scale. The average atherosclerosis [(aortic arch and thoracic aorta)÷2] was: SOS‐1.35; SSO‐0.97; POP‐0.83; and PPO‐1.80. Fecal fat excretion (an indicator of fat absorption) was higher in the two groups fed the stearic acid‐rich fats and lower in groups fed the palmitic acid‐rich fats. There were no differences in low density lipoprotein particle size. The results confirm previous findings concerning the increased atherogenicity of fats bearing palmitic acid at the sn‐2 position. The mechanism underlying these observations is moot but may, in part, reflect greater absorption of the atherogenic fat.
l‐Carnitine effects on chemical composition of plasma lipoproteins of rabbits fed with normal and high cholesterol diets
Authors: Diaz Maritza , Lopez Flor , Hernandez Frank , Urbina Julio A.
Published: November 2006

l‐Carnitine plays an important role in the mitochondrial uptake of long‐chain fatty acids in mammals. It has recently been shown that this compound has a marked hypo‐cholesterolemic effect when used in conjunction with lipid‐rich diets. The aim of this study was to investigate the effects of l‐carnitine on the fatty acid composition of plasma lipoproteins in rabbits fed with different diets. Four different groups were investigated: group I (standard diet), group II (standard diet supplemented with l‐carnitine at 80 mg/kg), group III (standard diet supplemented with 0.5% cholesterol), and group IV (standard diet supplemented with 0.5% cholesterol plus l‐carnitine at 80 mg/kg). The feeding period was 126 d. Total plasma cholesterol was indistinguishable in groups I and II, but increased nearly 40‐fold in group III. This increment was reduced by 50% in group IV. Correspondingly, total cholesterol content in lipoprotein fractions [very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL) separated by agarose gel chromatography was the same for groups I and II, while for animals fed a cholesterol‐rich diet (III) total cholesterol in VLDL+LDL increased nearly 100‐fold when compared with groups I and II but, again, the increment was reduced by 50% in group IV. In contrast, total cholesterol in HDL increased only fivefold for both groups III and IV when compared with groups I and II, indicating no effects of l‐carnitine on this parameter. The reduction of total cholesterol in VLDL+LDL particles in animals fed a cholesterol‐rich diet plus l‐carnitine was associated with a marked decrease in the ratio of cholesteryl ester to free cholesterol and a dramatic increase in their phospholipid content; opposite effects were observed for HDL. l‐Carnitine induced a marked decrease in the saturated to unsaturated C16+C18 fatty acid ratio in cholesteryl esters associated with VLDL and LDL from animals fed with both normal and cholesterol‐rich diets. The opposite effect (a large increase in the saturated to unsaturated fatty acid ratio) was observed for both cholesteryl esters and phospholipids associated with HDL in animals fed with both diets. The results suggested that the hypocholesterolemic effects of l‐carnitine could be associated with increased systemic breakdown of cholesteryl esters, a probable increase in reverse cholesterol transport, and the stabilization of a phospholipid‐based structure of VLDL+LDL particles.
Lipid metabolism and tissue composition in Atlantic salmon (Salmo salar L.)—Effects of capelin oil, palm oil, and oleic acid‐enriched sunflower oil as dietary lipid sources
Authors: Torstensen Bente E. , Lie Øyvind , Frøyland Livar
Published: November 2006

Triplicate groups of Atlantic salmon (Salmo salar L.) were fed four diets containing different oils as the sole lipid source, i.e., capelin oil, oleic acid‐enriched sunflower oil, a 1∶1 (w/w) mixture of capelin oil and oleic acid‐enriched sunflower oil, and palm oil (PO). The β‐oxidation capacity, protein utilization, digestibility of dietary fatty acids and fatty acid composition of lipoproteins, plasma, liver, belly flap, red and white muscle were measured. Further, the lipid class and protein levels in the lipoproteins were analyzed. The different dietary fatty acid compositions did not significantly affect protein utilization or β‐oxidation capacity in red muscle. The levels of total cholesterol, triacylglycerols, and protein in very low density lipoprotein (VLDL), low density lipoprotein (LDL), high density lipoprotein (HDL), and plasma were not significantly affected by the dietary fatty acids. VLDL, LDL, and HDL fatty acid compositions were decreasingly affected by dietary fatty acid composition. Dietary fatty acid composition significantly affected both the relative fatty acid composition and the amount of fatty acids (mg fatty acid per g tissue, wet weight) in belly flap, liver, red and white muscle. Apparent digestibility of the fatty acids measured by adding yttrium oxide as inert marker, was significantly lower in fish fed the PO diet compared to the other three diets.
Preparation of functional liposomes with peptide ligands and their binding to cell membranes
Authors: Yagi Nobuhiro , Ogawa Yoshikatsu , Kodaka Masato , Okada Tomoko , Tomohiro Takenori , Konakahara Takeo , Okuno Hiroaki
Published: November 2006

Two novel lipopeptides, which have the peptide ligands [α‐melanocyte stimulating hormone (α‐MSH)] sequence and repeated [Gly‐Arg‐Gly‐Asp‐Se (GRGDS) sequence[, are designed, synthesized by the solid‐phase method, and introduced into liposome membranes by the freeze‐thaw method. These liposomes bearing the peptide ligands on their surface are expected to bind to cell membranes. We have confirmed that the lipopeptides are introduced into liposome membranes almost quantitatively, while such a high degree of incorporation has not been accomplished in conventional methods. In this respect, the present method is superior to prepare surface‐modified liposomes that are applicable to drug carriers and so on. We have also confirmed by using immunoelectron microscopy that the peptide ligands are actually located in an aqueous phase. It has been shown by flow cytometry that the liposome bearing α‐MSH peptide ligand binds to B16 cells and the liposome bearing the repeated GRGDS sequence binds to NIH3T3 cells.
Quantitative analysis of long‐chain trans‐monoenes originating from hydrogenated marine oil
Authors: Wilson Robert , Lyall Karin , Payne J. Anne , Riemersma Rudolph A.
Published: November 2006

Gas chromatography (GC) is used for the analysis of trans‐fatty acids in partially hydrogenated vegetable oils. Although trans‐isomers of C18 carbon length predominate in partially hydrogenated vegetable oils, trans‐isomers of C20 and C22 carbon length occur in partially hydrogenated fish oil. We report a simple silver ion chromatographic combined with capillary GC technique for quantitative analysis of trans‐monoenes derived from partially hydrogenated fish oil. Silver nitrate thinlayer chromatographic (TLC) plates are developed in toluene/hexane (50∶50, vol/vol). Fatty acid methyl esters are separated into saturates (Rf 0.79), trans‐monoenes (Rf 0.49), cis‐monoenes (Rf, 0.27), dienes (Rf, 0.10), and polyunsaturated fatty acids with three or more double bonds remaining at the origin. The isolated trans‐monoenes are quantitatively analyzed by capillary GC. The technique of argentation TLC with GC analysis of isolated methyl esters is highly reproducible with 4.8% variation (i.e., coefficient of variation, CV%) in Rf values and 4.3 and 6.9% CV% in quantification within batch and between batch, respectively. Furthermore, the combined technique revealed that direct GC analysis underestimated the trans‐content of margarines by at least 30%. In this study, C20 and C22trans‐monoenes were found in relatively large quantities; 13.9% (range 10.3–19.6%) and 7.5% (range 5.3–11.5%), respectively, in margarine purchased in 1995, but these C20 and C22trans‐monoenes were much reduced (0.1%) in a fresh selection of margarine purchased in 1998. Compositional data from labels underestimated the trans‐content of margarines, especially those dervied from hydrogenated marine oil. Low levels of C20trans‐monoenes (range 0.1–0.3%) and C22trans‐monoenes (range 0.0–0.1%) were identified in adipose tissue obtained from healthy volunteers in 1995, presumably indicating consumption of partially hydrogenated fish oil.
Evaluation of brain long‐chain acylcarnitines during cerebral ischemia
Authors: Deutsch J. , Kalderon B. , Purdon A. D. , Rapoport S. I.
Published: November 2006

Concentration and distribution of long‐chain acylcarnitines in control microwaved and ischemic (decapitated) rat brain were measured by electrospray ionization tandem mass spectrometry. The total acylcarnitine concentration from control rat brains equaled 7–8 nmol/g wet weight brain, about one‐fourth the total concentration of long‐chain acyl‐CoA, indicating a small role in buffering the total acyl‐CoA pool concentration. Furthermore, acylcarnitine did not differ between ischemic and control rat brain with regard to total concentration or concentrations of molecular species of acylcarnitine. Therefore, the size of the acylcarnitine pool in brain is not affected by the dramatic increase in unesterified fatty acids (∼4×) that occurs in ischemia.
Follow‐up of the Δ4 to Δ16 trans‐18∶1 isomer profile and content in French processed foods containing partially hydrogenated vegetable oils during the period 1995–1999. Analytical and nutritional implications
Authors: Wolff Robert L. , Combe Nicole A. , Destaillats Frédéric , Boué Carole , Precht Dietz , Molkentin Joachim , Entressangles Bernard
Published: November 2006

A survey of the total content of trans‐18∶1 acids and their detailed profile in French food lipids was conducted in 1995–1996, and 1999. For this purpose, 37 food items were chosen from their label indicating the presence of partially hydrogenated vegetable oils (PHVO) in their ingredients. The content as well as the detailed profile of these isomers was established by a combination of argentation thin‐layer chromatography and gas‐liquid chromatography (GLC) on long polar capillary columns. With regard to the mean trans‐18∶1 acid contents of extracted PHVO, a significant decrease was observed between the two periods, i.e., from 26.9 to 11.8% of total fatty acids. However, only minor differences were noted in the mean relative distribution profiles of individual trans‐18∶1 isomers with ethylenic bonds between positions Δ4 and Δ16 for the two periods. The predominant isomer was Δ9–18∶1 (elaidic) acid, in the wide range 15.2–46.1% (mean, 27.9±7.2%) of total trans‐18∶1 acids, with the Δ10 isomer ranked second, with a mean of 21.3% (range, 11.6 to 27.4%). The content of the unresolved Δ6 to Δ8 isomer group was higher than the Δ11 isomer (vaccenic acid), representing on average 17.5 and 13.3%, respectively. Other isomers Δ4, Δ5, Δ12, Δ13/Δ14, Δ15, and Δ16, were less than 10% each: 1.0, 1.6, 7.4, 7.1, 1.8, and 1.0%, respectively. However, considering individual food items, it was noted that none of the extracted PHVO were identical to one another, indicating a considerable diversity of such fats available to the food industry. A comparison of data for French foods with similar data recently established for Germany indicates that no gross differences occur in PHVO used by food industries in both countries. Estimates for the absolute mean consumption of individual isomers from ruminant fats and PHVO are made for the French population and compared to similarly reconstructed hypothetical profiles for Germany and North America. Differences occur in the total intake of trans‐18∶1 acids, but most important, in individual trans‐18∶1 isomer intake, with a particular increase of the Δ6–Δ8 to Δ10 isomers with increasing consumption of PHVO. It is inferred from the present and earlier data that direct GLC of fatty acids is a faulty procedure that results (i) in variable underestimates of total trans‐18∶1 acids, (ii) in a loss of information as regards the assessment of individual isomeric trans‐18∶1 acids, and (iii) in the impossibility of comparing data obtained from human tissues if the relative contribution of dietary PHVO and ruminant fats is not known.
Variablity of the intestinal uptake of lipids is genetically determined in mice
Authors: Keelan M. , Hui D. Y. , Wild G. , Clandinin M. T. , Thomson A. B. R.
Published: November 2006

The response of the plasma cholesterol concentration to changes in dietary lipids varies widely in humans and animals. There are variations in the in vivo absorption of cholesterol between different strains of mice. This study was undertaken in three strains of inbred mice to test the hypotheses that: (i) there are strain differences in the in vitro uptake of fatty acids and cholesterol and (ii) the adaptability of the intestine to respond to variations in dietary lipids is genetically determined. An in vitro intestinal ring technique was used to assess the uptake of medium‐ and long‐chain fatty acids and cholesterol into jejunum and ileum of adult DBA/2, C57BL6, and C57L/J mice. The jejunal uptake of cholesterol was similar in C57L/J, DBA/2, or C57BL6 fed ad libitum a low‐fat (5.7% fat, no cholesterol) chow diet. This is in contrast to a previous demonstration that in vivo cholesterol absorption was lower in C57L/J than in the other murine strains. The jejunal uptake of several long‐chain fatty acids was greater in DBA/2 fed for 4 wk the high‐fat (15.8% fat and 1.25% cholesterol) as compared with the low‐fat diet. Furthermore, on the high‐fat diet, the uptake of many long‐chain fatty acids was higher in DBA/2 than in C57BL6 or C57L/J. The differences in cholesterol and fatty acid uptake were not explained by variations in food uptake, body weight gain, or the weight of the intestine. In summary: (i) there are strain differences in the in vitro intestinal uptake of fatty acids but not of cholesterol; (ii) a high‐fat diet enhances the uptake of long‐chain fatty acids in only one of the three strains examined in this study; and (iii) the pattern of strain‐ and diet‐associated alterations in the in vivo absorption of cholesterol differs from the pattern of changes observed in vitro. We speculate that genetic differences in cholesterol and fatty acid uptake are explained by variations in the expression of protein‐mediated components of lipid uptake.
Response of urinary lipophilic aldehydes and related carbonyl compounds to factors that stimulate lipid peroxidation in vivo
Authors: Csallany A. Saari , Kim Song‐Suk , Gallaher Daniel D.
Published: November 2006

Peroxidation of lipids results in the formation of a number of aldehydic and other carbonyl‐containing secondary degradation products. The effect of peroxidative stimuli mediated by vitamin E deficiency, a diet high in polyunsaturated fatty acids (containing cod liver oil), and carbon tetrachloride administration on urinary excretion of a number of lipophilic aldehydes and related carbonyl compounds was examined in rats. These secondary lipid peroxidation products were measured as 2,4‐dinitrophenylhydrazine derivatives. All three treatments increased urinary excretion of secondary lipid peroxidation products, although the pattern of excretion of these products varied somewhat among the treatments. Significant increases were found in butanal, hexanal, octanal. butan‐2‐one, pentan‐2‐one, hex‐2‐enal, hepta‐2,4‐dienal, 4‐hydroxyhex‐2‐enal, 4‐hydroxyoct‐2‐enal, 4‐hydroxynon‐2‐enal, and a number of unidentified carbonyl compounds. These results suggest that urinary excretion of these lipophilic secondary lipid peroxidation products is a useful and noninvasive marker of whole‐body lipid peroxidation.
n−3 Fatty acid deficiency decreases phosphatidylserine accumulation selectively in neuronal tissues
Authors: Hamilton Jillonne , Greiner Rebecca , Salem Norman , Kim Hee‐Yong
Published: November 2006

We have previously shown that the docosahexaenoate (22∶6n−3) status in membrane phospholipids influences the biosynthesis and accumulation of phosphatidylserine (PS) in brain microsomes and C6 glioma cells. In the present study, we investigated whether the observed effect of membrane docosahexaenoic acid status on PS accumulation is universal or occurs specifically in neuronal tissues. We observed that rat brain cortex, brain mitochondria, and olfactory bulb, where 22∶6n−3 is highly concentrated, contain significantly higher levels of PS in comparison to liver and adrenal, where 22∶6n−3 is a rather minor component. Phospholipid molecular species analysis revealed that in brain cortex, mitochondria, and olfactory bulb 18∶0,22∶6n−3 was the most abundant species representing 45–65% of total PS. In nonneuronal tissues such as liver and adrenal, 18∶0,20∶4n−6 was the major PS species. Dietary depletion of n−3 fatty acids during prenatal and postnatal developmental periods decreased the brain 22∶6n−3 content by more than 80%, with a concomitant increase in 22∶5n−6 in all tissues. Under these conditions, an approximately 30–35% reduction in total PS in rat brain cortex, brain mitochondria, and olfactory bulb was observed, while PS levels in liver and adrenal were unchanged. The observed reduction of PS content in neuronal membranes appears to be due to a dramatic reduction of 18∶0,22∶6n−3‐PS without complete replacement by 18∶0,22∶5n−6‐PS. These results establish that variations in membrane 22∶6n−3 fatty acid composition have a profound influence on PS accumulation in neuronal tissues where 22∶6n−3 is abundant. These data have implications in neuronal signaling events where PS is believed to play an important role.
The questionable role of a microsomal °8 acyl‐CoA‐dependent desaturase in the biosynthesis of polyunsaturated fatty acids
Authors: Chen Qi , Yin Feng Qin , Sprecher Howard
Published: November 2006

Several experimental approaches were used to determine whether rat liver and testes express an acyl‐CoA‐dependent δ8 desaturase. When [1‐14C]5, 11, 14‐eicosatrienoic acid was injected via the tail vein, or directly into testes, it was incorporated into liver and testes phospholipids, but it was not metabolized to other labeled fatty acids. When [1‐14C]11, 14‐eicosadienoic acid was injected, via the tail vein or directly into testes, or incubated with microsomes from both tissues, it was only metabolized to 5,11, 14‐eicosatrienoic acid. When ethyl 5,5,11,11,14,14‐d6‐5,11,14‐eicosatrienoate was fed to rats maintained on a diet devoid of fat, it primarily replaced esteri‐fied 5,8,11‐eicosatrienoic acid, but not arachidonic acid. No labeled linoleate or arachidonate were detected. Dietary ethyl linoleate and ethyl 19,19,20,20‐d4‐1,2‐13C‐11,14‐eicosadienoate were about equally effective as precursors of esterified arachidonate. The doubly labeled 11,14‐eicosadienoate was metabolized primarily by conversion to 17,17,18,18‐d4‐9,12‐ocatdeca‐dienoic acid, followed by its conversion to yield esterified arachidonate, with a mass four units greater than endogenous arachidonate. In addition, the doubly labeled substrate gave rise to a small amount of arachidonate, six mass units greater than endogenous arachidonate. No evidence was obtained, with the radiolabeled substrates, for the presence of a δ8 desaturase. However, the presence of an ion, six mass units greater than endogenous arachidonate when doubly labeled 11, 14‐eicosa‐dienoate was fed, suggests that a small amount of the substrate may have been metabolized by the sequential use of δ8 and δ5 desaturases.
Conjugated linoleic acid suppresses triglyceride accumulation and induces apoptosis in 3T3‐L1 preadipocytes
Authors: Evans M. , Geigerman C. , Cook J. , Curtis L. , Kuebler B. , McIntosh M.
Published: November 2006

Four sets of experiments were conducted to examine the influence of conjugated linoleic acid (CLA) isomers during proliferation and differentiation of cultures of 3T3‐L1 preadipocytes using physiological culturing conditions. Cultures treated with either albumin [bovine serum albumin (BSA) vehicle] or linoleic acid (LA) served as controls. For the proliferation study (Expt. 1), cells were cultured in media containing a crude mixture of CLA isomers or pure LA at 0, 10, 50, or 200 μM for 4 d. Preadipocyte proliferation (cell number, 3H‐thymidine incorporation into DNA) decreased as the level of CLA increased in the cultures. In contrast, LA had no impact on DNA synthesis. In Experiment 2a, postconfluent cultures were grown in media containing a crude mixture of CLA isomers or LA at 0, 10, 50, or 200 μM for the next 6 d. Postconfluent cultures supplemented with 50–200 μM CLA had less triglyceride (TG) and were smaller in size than cultures supplemented with similar amounts of LA. In Experiment 2b, postconfluent cultures supplemented with 200 μM of a crude mixture of CLA isomers or LA were harvested on days 1, 3, 6, or 9. Differences in TG content of cultures supplemented with 200 μM CLA compared to control and LA‐supplemented cultures became apparent after 3 d of culture. Experiments 3a and 3b examined whether the fatty acid vehicle (BSA vs. ethanol) or the vitamin E status (±0.2 mM α‐tocopherol) of the cultures altered CLA's impact on preadipocyte TG content. In Experiment 3a, ethanol‐treated cultures had more TG than non‐ethanol‐treated cultures regardless of the fatty acid treatment. In Experiment 3b, cultures treated with 100 μM of either a crude mixture of CLA or the trans‐10, cis‐12 CLA isomer without supplemental vitamin E for 6 d had less TG than CLA‐treated cultures containing vitamin E. In Experiment 4, postconfluent cultures were grown in media containing 100 μM LA or either a crude mixture of CLA isomers or the trans‐10, cis‐12 CLA isomer for 24–96 h to assess CLA's influence on the cell cycle and indices of apoptosis. Cultures treated with 100 μM CLA for 24–96 h had more apoptotic cells than BSA‐ or LA‐treated cultures. Furthermore, cultures treated for 48 h with CLA had fewer cells in the S‐phase than control cultures. The effects of the trans‐10,cis‐12 CLA isomer were more pronounced than those of the crude mixture of CLA isomers. These data suggest that CLA may exert its antiobesity effects by inhibiting proliferation, attenuating TG content, and/or inducing apoptosis in (pre)adipocytes.
Kinetic properties of Penicillium cyclopium lipases studied with vinyl esters
Authors: Chahinian Henri , Nini Lylia , Boitard Elisabeth , Dubès Jean‐Paul , Sarda Louis , Comeau Louis‐Claude
Published: November 2006

Penicillium cyclopium produces two lipases with different substrate specificities. Lipase I is predominantly active on triacylglycerols whereas lipase II hydrolyzes mono‐ and diacylglycerols but not triacylglycerols. In this study, we compared the kinetic properties of P. cyclopium lipases and human pancreatic lipase, a classical triacylglycerol lipase, by using vinyl esters as substrates. Results indicate that P. cyclopium lipases I and II and human pancreatic lipase hydrolyze solutions of vinyl propionate or vinyl butyrate at high relative rates compared with emulsions of the same esters, although, in all cases, maximal activity is reached in the presence of emulsified particles, at substrate concentrations above the solubility limit. It appears that partially water‐soluble short‐chain vinyl esters are suitable substrates for comparing the activity of lipolytic enzymes of different origin and specificity toward esters in solution and in emulsion.
Current methods for the identification and quantitation of ceramides: An overview
Authors: Cremesti Aida E. , Fischl Anthony S.
Published: November 2006

Ceramides are key compounds in the metabolism of sphingolipids and are emerging as important second messengers for various cellular processes including cell cycle arrest, differentiation, senescence, apoptosis, and others. Because of their important biological functions, exact analysis of their molecular species and concentrations is crucial for elucidating their function and metabolism. Toward this goal, several methods have been developed for the identification and quantitation of cellular ceramide levels. Methods have been developed utilizing thin‐layer or high‐performance liquid chromatography. Mass spectrometry also has become increasingly utilized. The Escherichia coli diacylglycerol kinase assay is one of the most frequently used techniques for ceramide quantitation. This review presents a current summary of methods used for the identification and quantitation of ceramides.
Autoxidation of methyl linoleate: Identification of the bis‐allylic 11‐hydroperoxide
Authors: Brash Alan R.
Published: November 2006

Based on the understanding of lipid peroxidation as a free radical chain reaction, over 50 yr ago the three primary products of linoleic acid autoxidation were predicted to be the 9‐, 11‐, and 13‐hydroperoxides. The 9‐ and 13‐hydroperoxides were found at the time, but formation of 11‐hydroperoxylinoleate or any other bis‐allylic fatty acid hydroperoxide has not been reported hetetofore as a product of lipid peroxidation reactions. In vitamin E‐controlled autoxidation of methyl linoleate, the 11‐hydroperoxy derivative was identified as the next most prominent primary peroxidation product after the 9‐and 13‐hydroperoxides. It was present in approximately 5–10% of the abundance of the 9‐ or 13‐hydroperoxide. The structures of 11‐hydroperoxylinoleate and its 11‐hydroxy derivative were established by high‐pressure liquid chromatography, ultraviolet spectroscopy, gas chromatography‐mass spectroscopy, and 1H nuclear magnetic resonance spectroscopy. The 11‐hydroperoxide was not detectable in the absence of α‐tocopherol, indicating that efficient trapping of the 11‐peroxyl radical as the hydroperoxide is critical to permitting its accumulation.
Formation of 8‐oxo‐2′‐deoxyguanosine in the DNA of human diploid fibroblasts by treatment with linoleic acid hydroperoxide and ferric ion
Authors: Kaneko Takao , Tahara Shoichi
Published: November 2006

Lipid peroxides are suggested to be related to the occurrence of a variety of diseases including cancer and atherosclerosis. We examined whether lipid peroxides cause oxidative damage to DNA in intact cells. Linoleic acid hydroperoxide (LOOH) and ferric chloride were used at concentrations at which separate treatment had no effect on the formation of 8‐oxo‐2′‐deoxyguanosine (8‐oxodG) in DNA or the survival rate of cultured human diploid fibroblasts, TIG‐7. The amount of 8‐oxodG in the cellular DNA increased significantly when TIG‐7 cells were treated concurrently with LOOH and ferric chloride. In a LOOH concentration‐dependent manner 8‐oxodG was formed. However, no significant induction of the activities of superoxide dismutases, catalase, or glutathione peroxidase was observed under these conditions. The formation of 8‐oxodG by lipid hydroperoxides seems to be due to the generation of reactive species other than superoxide radicals and hydrogen peroxide. These results indicate that some species formed during the reaction of lipid hydroperoxides with ferric ion can cause oxidative damage to DNA.
Lipid peroxidation as determined by plasma isoprostanes is related to disease severity in mild asthma
Authors: Wood Lisa G. , Fitzgerald Dominic A. , Gibson Peter C. , Cooper David M. , Garg Manohar L.
Published: November 2006

Oxidative stress is believed to play an important role in the pathophysiology of asthma. Recently discovered F2‐isoprostanes, of which 8‐iso‐PGF2αis the most well‐known isomer, have emerged as the most reliable marker ofin vivooxidative stress. The aim of this study was to examine 8‐iso‐PGF2αas a biomarker of oxidative stress in mild asthma in relation to endogenous and dietary antioxidant protection. Total (free and esterified) plasma 8‐iso‐PGF2α, plasma dietary antioxidants (vitamins E and C,β‐carotene, Zn, and Se), and erythrocyte antioxidant enzyme activities (glutathione peroxidase and superoxide dismutase) were measured in 15 mild asthmatics and 15 age‐and sex‐matched controls. Total plasma 8‐iso‐PGF2αlevels [median (quartile 1‐quartile 3)] were significantly increased in the sthmatics [213 pg/mL (122–455) vs. 139 pg/mL (109–174),P=0.042]. The 8‐iso‐PGF2αlevels were found to be associated with clinical asthma severity (P=0.044) and inhaled corticosteroid use (P=0.027) in asthmatics. No differences were observed in the plasma dietary antioxidant vitamins. The asthmatics had significantly lower plasma levels of Zn (P=0.027) and Se (P=0.006). Plasma Se correlated negatively with 8‐iso‐PGF2α(r=−0.725,P=0.002). No differences between the groups were observed for glutathione peroxidase or superoxide dismutase, however, superoxide dismutase activity was negatively associated with asthma severity (P=0.042). In conclusion, oxidative stress is increased in mild asthmatics, as reflected by increased plasma levels of 8‐iso‐PGF2αand a deficiency in plasma Zn and Se. The isoprostane 8‐iso‐PGF2αmay provide a useful tool in intervention studies aimed at improving clinical status in asthma.
Calcium deficiency modifies polyunsaturated fatty acid metabolism in growing rats
Authors: Marra Carlos A. , de Alaniz María J. T.
Published: November 2006

Fatty acid desaturase activities were determined in liver microsomes from calcium‐deficient rats and compared to calcium‐sufficient ones. The calcium‐deprived diet (0.5 g/kg) administered for 60 d caused a 30% inhibition in the Δ5 desaturase activity and a 45–55% decrease in Δ6 and Δ9, respectively, facts that cannot be attributed to a reduction in food intake. In vitro addition of calcium, ethyleneglycol‐bis(β‐aminoethyl ether)N,N‐tetraacetic acid, and/or cytosol fractions from control or calcium‐deficient rats to microsomes from both groups of animals indicates that the reduced desaturase capacities would be the consequence of an indirect effect of calcium deprivation. The present work shows that the reduced unsaturated fatty acid biosynthesis might be the result of modifications in the physicochemical properties of microsomal membranes. Such changes could also be derived from the inhibition of phospholipase A2 activity induced by calcium deficiency.
The effect of low α‐linolenic acid diet on glycerophospholipid molecular species in guinea pig brain
Authors: Kurvinen J. ‐P. , Kuksis A. , Sinclair A. J. , Abedin L. , Kallio H.
Published: November 2006

The changes in guinea pig brain (cerebrum) glycerophospholipid molecular species resulting from a low α‐linolenic acid (ALA) diet are described. Two groups of six guinea pigs were raised from birth to 16 wk of age on either an n‐3 deficient diet containing 0.01 g ALA/100 g diet or n‐3 sufficient diet containing 0.71 g AlA/100 g diet. Molecular species of diradyl glycerophosphoethanolamine. (GroPEtn), glycerophosphocholine, glycerophosphoserine, and glycerophosphoinositol were analyzed by high‐performance liquid chromatography with on‐line electrospray ionization mass spectrometry (HPLC/ESI/MS). Alkenylacyl GroPEtn species were determined by comparing spectra before and after mild acid treatment while diacyl‐ and alkylacyl species were distinguished by HPLC/ ESI/MS. The proportions of phospholipid classes and of the diradyl GroPEtn subclasses were not altered by diet changes. The main polyunsaturated molecular species of diradyl GroPEtn subclasses and of phosphatidylcholine and phosphatidylserine (PtdSer) contained 16∶0, 18∶0, or 18∶1 in combination with docosahexaenoic acid (DHA, 22∶6n‐3), docosapentaenoic (DPA, 22∶5n‐6), or arachidonic acid (ARA, 20∶4n‐6). A significant proportion of DPA containing species were present in both diet groups, but in n‐3 fatty acid deficiency, the proportion of DPA increased and DHA was primarily replaced by DPA. The combined value of main DHA and DPA containing species in the n‐3 deficient group ranged from 91‐111% when compared with the n‐3 sufficient group, indicating a nearly quantitative replacement. The n‐3 fatty acid deficiency did not lower the content of ARA containing molecular species of PtdSer of the guinea pig brain as reported previously for the rat brain. The molecular species of phosphatidylinositol were not altered by n‐3 fatty acid deficiency. The present data show that the main consequence of a low ALA diet is the preferential replacement of DHA‐containing molecular species by DPA‐containing molecular species in alkenylacyl‐ and diacyl GroPEtn and PtdSer of guinea pig brain.