bluuebunny/crossref_metadata_2025_split 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

AbstractMuscle 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

AbstractMale 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

AbstractApolipoprotein 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

AbstractCycloartenol 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

AbstractThe 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

AbstractHigher 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

AbstractHairy 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

AbstractWith 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

AbstractWe 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

AbstractEarlier 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

Abstractl‐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

AbstractTriplicate 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

AbstractTwo 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

AbstractGas 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.