bluuebunny/crossref_metadata_2025 huggingface dataset:
Changes in body composition in mice during feeding and withdrawal of conjugated linoleic acid
Authors: Park Yeonhwa , Albright Karen J. , Storkson Jayne M. , Liu Wei , Cook Mark E. , Pariza Michael W.
Published: November 2006

Two experiments were conducted. In Experiment 1, 8‐wk‐old mice were fed control diet or diet supplemented with 0.5% conjugated linoleic acid (CLA) to study the effect of CLA on body composition (CLA: 40.8–41.1% c‐9,t‐11 isomer, 43.5–44.9% t‐10,c‐12 isomer). The data for CLA‐fed mice vs. controls described parallel but significantly distinct responses for both absolute and relative changes in body fat mass (reduced in CLA‐fed mice) and for relative changes in whole body protein and whole body water (both of which were increased in CLA‐fed mice). In the CLA‐fed mice, the effect on whole body protein appeared to precede the reduction in body fat mass. In Experiment 2, weanling mice were fed control diet or diet supplemented with 0.5% CLA for 4 wk (test group), at which time all mice were fed control diet devoid of added CLA. The test group exhibited significantly reduced body fat and significantly enhanced whole body water relative to controls at the time of diet change. Time trends for changes in relative body composition were described by parallel lines where the test group exhibited significantly less body fat but significantly more whole body protein, whole body water, and whole body ash than controls. Tissue CLA levels declined following the withdrawal of CLA from the diet. In skeletal muscle of mice fed CLA‐supplemented diet, the t‐10,c‐12 isomer was cleared significantly faster than the c‐9,t‐11 CLA isomer.
Activation of acyl‐CoA cholesterol acyltransferase: Redistribution in microsomal fragments of cholesterol and its facilitated movement by methyl‐β‐cyclodextrin
Authors: Cheng Donghui , Tipton Carl L.
Published: November 2006

Acyl‐CoA cholesterol acyltransferase (ACAT) (EC 2,3,1.26) in the yolk sac membrane of chicken eggs plays an important role in the transport of lipids, which serve as both structural components and as an energy source during embryogenesis. ACAT from the yolk sac membrane of chicken eggs 16 d after fertilization has higher activity and better stability than its mammalian liver counterpart. During our study of the avian enzyme, ACAI was found to be activated up to twofold during storage at 4°C. The activation was investigated, and data suggest that redistribution of cholesterol within microsomal vesicles leads to the increase. Methyl‐β‐cyclodextrin (MβCD) increases activation an additional twofold, possibly by facilitating the movement of cholesterol within microsomal fragments and allowing redistribution of cholesterol in lipid bilayers to a greater extent. Treatment of microsomes with MβCD removes cholesterol from the membranes. Controlled amounts of cholesterol can be restored to the membranes by mixing them with cholesterol‐phosphatidylcholine liposomes in the presence of MβCD. Under these conditions, the plot of ACAT vs. cholesterol mole fraction in the liposomes is sigmoidal. The finding that MβCD can enhance cholesterol transfer between liposomes and microsomes and reduce the limitation of slow movement et nonpolar molecules in aqueous media should make cyclodextrins more useful in in vitro studies of apolar molecule transport between membrane vesicles.
Transformation of bile acids and sterols by clostridia (fusiform bacteria) in Wistar rats
Authors: Uchida Kiyohisa , Satoh Takashi , Narushima Seiko , Itoh Kikuji , Takase Haruto , Kuruma Kazuo , Nakao Hiroyuki , Yamaga Nobuo , Yamada Kazuo
Published: November 2006

The effects on bile acid and sterol transformation of clostridia (fusiform bacteria), the dominant intestinal bacteria in rodents (ca. 1010 counts per g wet feces) were examined in Wistar rats. After inoculation of clostridia into germ‐free rats and into rats previously inoculated solely with Escherichia coli, most of the endogenous bile acids were deconjugated, and cholic acid and chenodeoxycholic acid were 7α‐dehydroxylated to deoxycholic acid and lithocholic acid, respectively. Tauro‐β‐muricholic acid, another major bile acid in rats, was deconjugated, but only part of it (ca. 30%) was transformed into hyodeoxycholic acid. Cholesterol and sitosterol were also reduced to coprostanol and sitostanol, respectively. Escherichia coli transformed neither bile acids nor sterols. These data suggest that clostridia play an imporant role in the formation of secondary bile acids and coprostanol in rats.
White adipose tissue fatty acids of alpine marmots during their yearly cycle
Authors: Cochet Nathalie , Georges Bruno , Meister Roger , Florant Gregory L. , Barré Hervé
Published: November 2006

Alpine marmots (Marmota marmota) were maintained on a laboratory diet, and the fatty acid composition of gonadal and subcutaneous whilte adipose tissues (WAT) was studied during a yearly cycle. Fatty acids (FA) released from isolated adipocytes were also identified after stimulation of in vitro lipolysis. Analysis of the FA composition of WAT depots showed that marmot WAT mainly contained monounsaturated FA(65%, mostly oleic, acid, 18:1n‐9) although laboratory food contained 45% of linoleic acid (18:2n‐6) and only 21% of 18:1n‐9. During stimulated lipolysis, saturated FA were preferentially released from isolated adipocytes whereas unsaturated FAs were retained. Despite this selective release of FA from isolated WAT cells in vitro, and despite the FA composition of the food, marmots maintained a constant FA composition in both WAT depots throughout the year. Six months of hibernation and fasting as well as an intense feeding period did not affect this composition. The potential adaptive benefit of such regulation of WAT composition, based on a high level of monounsaturated FA, might be to maintain fat with appropriate physical properties allowing animals to accommodate to and survive the wide range of body temperatures experienced during hibernation.
Fatty acid composition of 19 species of fish from the black sea and the Marmara Sea
Authors: Tanakol Refik , Yazici Zeliha , Şener Erdal , Sencer Ergin
Published: November 2006

Evidence suggests that differences in fatty acid composition among various fish species may be due to differences in diet or to environmental factors such as temperature, salinity, and depth at which the fish are caught. The beneficial effects of a diet containing fish on cardiovascular or other diseases have been associated with their high content of eicosapentaenoic (20∶5n‐3) and docosahexaenoic (22∶6n‐3) acids. In this study we analyzed the fatty acid composition of the flesh of 18 different species of marine fish and of cultured rainbow trout. The fish were obtained from the Black and the Marmara Seas, both of which have unique biological and ecological systems as well as eutrophication and pollution. The contents of 20∶5n‐3 and 22∶6n‐3 in the marine fish ranged from 4.2 to 13.3 wt% of total fatty acids, and from 6.6 to 40.8 wt%, respectively. The most important differences from other studies on oceanic fish were the tendencies toward higher percentages of 16∶0 and 22∶6n‐3. The n‐3 series of polyunsaturated fatty acids were present as 32.4±1.9% of the total fatty acids. The present study suggests that mature and immature Pomatomus saltator, as well as Engraulis encrasicolus, Mullus surmuletus, Sardina pilchardus, Mugil cephalus, and Sarda sarda may be preferred for the Turkish diet as a result of their high 20∶5 n‐3 and 22∶6 n‐3 contents. The cultured rainbow trout Oncorhynchus mykiss is not as good a source of n‐3 fatty acids as are the marine fish.
Synthetic routes to lipidic diamines and amino alcohols: A class of potential antiinflammatory agents
Authors: Kokotos George , Constantinou‐Kokotou Violetta , Noula Caterina , Hadjipavlou‐Litina Dimitra
Published: November 2006

Simple and efficient methods for the synthesis of lipidic amino alcohols and diamines are described in this paper. Lipidic 2‐amino alcohols and 1,3‐diamines can be synthesized starting from synthetic lipidic α‐amino acids. Alternatively, commercially available lipidic 1,2‐diols may be used as starting material for the synthesis of 2‐amino alcohols. Initial experiments on the in vivo antiinflammatory activity of the compounds synthesized gave promising results.
Docosahexaenoic acid ingestion inhibits natural killer cell activity and production of inflammatory mediators in young healthy men
Authors: Kelley D. S. , Taylor P. C. , Nelson G. J. , Schmidt Perla C. , Ferretti Aldo , Erickson Kent L. , Yu Rina , Chandra Ranjit K. , Mackey B. E.
Published: November 2006

The purpose of this study was to examine the effects of feeding docosahexaenoic acid (DHA) as triacylglycerol on the fatty acid composition, eicosanoid production, and select activities of human peripheral blood mononuclear cells (PBMNC). A 120‐d study with 11 healthy men was conducted at the Metabolic Research Unit of Western Human Nutrition Reach Center. Four subjects (control group) were fed the stabilization diet throughout the study; the remaining seven subjects were fed the basal diet for the first 30 d, followed by 6 g DHA/d for the next 90 d. DHA replaced an equivalent amount of linoleic acid; the two diets were comparable in their total fat and all other nutrients. Both diets were supplemented with 20 mg d α‐tocopherol acetate per day. PBMNC fatty acid composition and eicosanoid production were examined on day 30 and 113; immune cell functions were tested on day 22, 30, 78, 85, 106, and 113. DHA feeding increased its concentration from 2.3 to 7.4 wt% in the PBMNC total lipids, and decreased arachidonic acid concentration from 19.8 to 10.7 wt%. It also lowered prostaglandin E2 (PGE2) and leukotriene B4 (LTB4) production, in response to lipopolysaccharide, by 60–75%. Natural killer cell activity and in vitro secretion of interleukin‐1β and tumor necrosis factor α were significantly reduced by DHA feeding. These parameters remained unchanged in the subjects fed the control diet. B‐cell functions as reported here and T‐cell functions that we reported previously were not altered by DHA feeding. Our results show that inhibitory effects of DHA on immune cell functions varied with the cell type, and that the inhibitory effects are not mediated through increased production of PGE2 and LTB4.
Fatty acid profile of buccal cheek cell phospholipids as an index for dietary intake of docosahexaenoic acid in preterm infants
Authors: Hoffman Dennis R. , Birch Eileen E. , Birch David G. , Uauy Ricardo
Published: November 2006

Cheek cells (buccal epithelia) were utilized as a noninvasive index of fatty acid status in a study of the effects of n−3 long chain polyunsaturated fatty acid supplementation on visual function in preterm infants. The fatty acid profile of cheek cell phospholipids was directly correlated with the dietary docosahexenoic acid (DHA) intake of infants receiving: (i) primarily human milk; (ii) n−3 fatty acid‐deficient, corn oil‐based, commercial formula (CO); (iii) α‐linolenic acid‐enriched, soy oilbased, commercial formula; or (iv) experimental formula enriched with soy and marine oils providing a DHA level equivalent to that in human milk. In a subset of infants with complete cheek cell fatty acid profiles and visual function assessments, preterm infants at both 36 wk (n=63) and 57 wk (n=45) postconceptional age had significantly (P<0.0005) reduced cheek cell phospholipid DHA levels in the n−3‐dificient, CO‐fed group compared to the other diet groups. The DHA content in cheek cell phospholipids was highly correlated (P<0.0005) with that of both red blood cell lipids and plasma phospholipids at the 36‐and 57‐wk time points. The DHA content in cheek cell lipids of infants at 36 wk was significantly correlated with electroretinographic responses (r=−0.29; P<0.03) and visual acuity (r=−0.31; P<0.02) as measured by visual‐evoked potentials (VEP). Cheek cell DHA was highly correlated (r=−0.57; P<0.0005) with VEP acuity at the 57‐wk time point. These results suggest that the fatty acid profile of cheek cells is a valid index of essential fatty acid status, can be monitored frequently, and is associated with functional parameters in infants.
Acyl‐CoA synthetase activity in liver microsomes from calcium‐deficient rats
Authors: Marra Carlos A. , de Alaniz María J. T.
Published: November 2006

A study on the kinetic properties of the nonspecific acyl‐coenzyme A (CoA) synthetase activity in liver microsomal vesicles from both normal and calcium‐deficient Wistar rats was carried out. After a 65‐d treatment, the calcium‐deficient diet reflected a 75% increase in the synthetase activity with respect to control animals. The apparent Vm was significantly enhanced, while the Km remained unchanged. We also provided experimental evidence about various fatty acids of different carbon length and unsaturation which depressed the biosynthesis of palmitoyl‐CoA following different behaviors in control or calcium‐deprived liver microsomes. In addition, we studied in detail the inhibition reflected by stearic, α‐linolenic, or arachidonic acids, in the biosynthesis of palmitoyl‐CoA in microsomal suspensions either from control or hypocalcemic rats. In control microsomes, stearic acid produced a pure competitive effect, while the other fatty acids followed a mixed‐type inhibition. The competitive effect of stearic acid was not observed in calcium‐deprived microsomes. At the same time, a mixed‐type inhibition produced by either α‐linolenic or arachidonic acid was diminished in deprived microsomes due to an increase in the noncompetitive component (αKi). These changes observed in apparent kinetic constants (Km, Vm, Ki, and αKi), as determined by Lineweaver‐Burks and Dixon plots, were attributed to the important alterations in the physicochemical properties of the endoplasmic reticulum membranes induced by the calcium‐deficient diet. The solubilization of the enzyme activity from both types of microsomes demonstrated that the kinetic behavior of the enzyme depends on the microenvironment in the membrane, and that the calcium ion plays a crucial role in determining the alterations observed.
The inhibitory guanine nucleotide‐binding protein Gi2α induces and potentiates adipocyte differentiation
Authors: Høvik Kjerstin E. , Wu Pengfei , Gordeladze Jan O.
Published: November 2006

The present study further elucidates the involvement of the α‐subunit of the GTP‐binding protein Gi2 in the differentiation of murine 313‐L1 cells. Control and vector‐transfected cells attained a fully differentiated adipocyte phenotype showing ample lipid droplets. Cells expressing wild type (WT)‐Gi2α or the constitutively active R179E‐Gi2α, however, became enlarged, less confluent, and produced large amounts of lipids. Differentiation consistently increased the triglyceride (TAG) content in control cells. In both WT‐Gi2α and R179E‐Gi2α clones, a marked increase in TAG could be detected even prior to insulin/dexamethasone/isobutyl methylxanthine exposure. The activity of palmitoyl‐CoA synthetase (PCS) and glycerophosphate acyltransferase (GPAT) also increased upon differentiation. WT‐Gi2α and R179E‐Gi2α overexpression also enhanced PCS and GPAT activities even before differentiation medium was added. The total amount of phospholipids (PL) generally increased upon differentiation; however, pre‐ and postdifferentiation values were insignificantly different in cells expressing WT‐Gi2α and R179E‐Gi2α. Differentiation altered the PL profile with a relative shift from phosphatidylcholine and phosphatidylethanolamine to phosphatidylinositol (PI) in differentiated cells. Finally, differentiation yielded a general increase in the activity of basal PI‐phospholipase‐C activity. Again, cells expressing WT‐Gi2α and R179E‐Gi2α demonstrated elevated enzyme activity and enhanced second messenger accumulation subsequent to differentiation. In summary, cells with the R179E‐mutants of Gi2α exhibited stimulated lipid turnover and accumulation in both undifferentiated and differentiated cells.
Isolation and identification of a mouse brain protein recognized by antisera to heart fatty acid‐binding protein
Authors: Pu Lixia , Annan Roland S. , Carr Steven A. , Frolov Andrey , Wood W. Gibson , Spener Friedrich , Schroeder Friedhelm
Published: November 2006

Although a novel brain‐specific fatty acid‐binding protein (B‐FABP) was recently cloned, the identity of a second fatty acid‐binding protein detected with antibodies to the heart (H‐FABP) has not been clearly resolved. The present investigation, using matrix‐assisted laser desorption mass spectrometry, showed that this protein was a form of H‐FABP whose N‐terminal amino acid was neither methionine nor was it acetylated. Furthermore, isoelectric focusing revealed two major isoforms, a major band pl 7.4 and a minor band pl 6.4, in a distribution pattern opposite to that observed for H‐FABP in the heart. Tryptic peptide mass maps of the in‐gel digested SDS polyacrylamide gel electrophoresis protein bands showed that the two isoforms differed only in a single peptide corresponding to residues 97–106 of the heart H‐FABP sequence. This peptide had an [M+H]+ ion of either 1205.62 (pl 7.4) or 1206.53 (pl 6.4), consistent with a single amino acid substitution, Asp98 or Asn98. Whereas it is well established that both H‐FABP and B‐FABP interact with polyunsaturated fatty acids, we showed that they also significantly alter plasma membrane cholesterol dynamics in a manner opposite to that of another brain lipidbinding protein, sterol carrier protein‐2. In summary, the data demonstrated for the first time that the H‐FABP from brain, while nearly identical to H‐FABP from heart, differed significantly in isoform distribution and in amino terminal structure from heart H‐FABP. This suggests that the brain and heart H‐FABP may not necessarily function identically in these tissues.
Metabolic profile of linoleic acid in stored apples: Formation of 13(R)‐hydroxy‐9(Z),11(E)‐octadecadienoic acid
Authors: Beuerle Till , Schwab Wilfried
Published: November 2006

During our ongoing project on the biosynthesis of R‐(+)‐octane‐1,3‐diol the metabolism of linoleic acid was investigated in stored apples after injection of [1‐14C]‐, [9,10,12,13‐3H]‐, 13C18‐ and unlabeled substrates. After different incubation periods the products were analyzed by gas chromatography‐mass spectroscopy (MS), high‐performance liquid chromatography‐MS/MS, and HPLC‐radiodetection. Water‐soluble compounds and CO2 were the major products whereas 13(R)‐hydroxy‐ and 13‐keto‐9(Z),11(E)‐octadecadienoic acid, 9(S)‐hydroxy‐and 9‐keto‐10(E),12(Z)‐octadecadienoic acid, and the stereoisomers of the 9,10,13‐ and 9,12,13‐trihydroxyoctadecenoic acids were identified as the major metabolites found in the diethyl ether extracts. Hydroperoxides were not detected. The ratio of 9/13‐hydroxy‐ and 9/13‐keto‐octadecadienoic acid was 1∶4 and 1∶10, respectively. Chiral phase HPLC of the methyl ester derivatives showed enantiomeric excesses of 75% (R) and 65% (S) for 13‐hydroxy‐9(Z),11(E)‐octadecadienoic acid and 9‐hydroxy‐10(E),12(Z)‐octadecadienoic acid, respectively. Enzymatically active homogenates from apples were able to convert unlabeled linoleic acid into the metabolites. Radiotracer experiments showed that the transformation products of linoleic acid were converted into (R)‐octane‐1,3‐diol. 13(R)‐Hydroxy‐9(Z), 11(E)‐octadecadienoic acid is probably formed in stored apples from 13‐hydroperoxy‐9(Z),11(E)‐octadecadienoic acid. It is possible that the S‐enantiomer of the hydroperoxide is primarily degraded by enzymatic side reactions, resulting in an enrichment of the R‐enantiomer and thus leading to the formation of 13(R)‐hydroxy‐9(Z),11(E)‐octadecadienoic acid.
Anomalous enantioselectivity in the sharpless asymmetric dihydroxylation reaction of 24‐nor‐5β‐cholest‐23‐ene‐3α,7α,12α‐triol: Synthesis of substrates for studies of cholesterol side‐chain oxidation
Authors: Ertel Norman H. , Dayal Bishambar , Rao Kashav , Salen Gerald
Published: November 2006

Recently we described a block in bile acid synthesis in cerebrotendinous xanthomatosis (CTX), a lipid storage disease related to an inborn error of bile acid metabolism. In this disease a defect in hepatic microsomal (24S) hydroxylation blocks the transformation of 5β‐cholestane‐3α,7α,12α,25‐tetrol into (24S) 5β‐cholestane‐3α,7α,12α,24,25‐pentol and cholic acid. Mitochondrial cholesterol 27‐hydroxylation has also been reported to be abnormal in CTX subjects, but the relative importance of the enzymatic defect in this alternative microsomal pathway (namely, the 24S hydroxylation of 5β‐cholestane‐3α,7α,12α,25‐tetrol relative to the abnormality in mitochondrial 27‐hydroxylase) has not been established in CTX. To delineate the sequence of side‐chain hydroxylations and the enzymatic block in bile acid synthesis, we synthesized the (23 R and 23 S) 24‐nor‐5β‐cholestane‐3α,7α,12α,23,25‐pentols utilizing a modified Sharpless asymmetric dihydroxylation reaction on 24‐nor‐5β‐cholest‐23‐ene‐3α,7α,12α‐triol, a C26 analog of the naturally occurring C27 bile alcohol, 5β‐cholest‐24‐ene‐3α,7α,12α‐triol. Stereospecific conversion of the unsaturated 24‐nor triol to the corresponding chiral compounds (23R and 23S), 24‐nor‐5β‐cholestane‐3α,7α,12α,23,25‐pentols, was quantitative. However, conversion of the unsaturated 24‐nor triol to the chiral nor‐pentols had absolute stereochemistry opposite to the products predicted by the Sharpless steric model. The absolute configurations and enantiomeric excess of the C26 nor‐pentols and the C27 pentols (synthesized from 5β‐cholest‐24‐ene‐3α,7α,12α‐triol for comparison) were confirmed by nuclear magnetic resonance and lanthanide‐induced circular dichroism Cotton effect measurements. These results may contribute to a better understanding of the role of the 24S‐hydroxylation vs. 27‐hydroxylation step in cholic acid biosynthesis.
Simultaneous determination of RRR‐ and SRR‐α‐tocopherols and their quinones in rat plasma and tissues by using chiral high‐performance liquid chromatography
Authors: Kiyose Chikako , Kaneko Kazuyo , Muramatsu Riho , Ueda Tadahiko , Igarashi Osamu
Published: November 2006

We established a method to simultaneously determine RRR‐ and SRR‐α‐tocopherol (α‐Toc) and their quinones in biological samples by chiral‐phase high‐performance liquid chromatography (HPLC). α‐Toc had a shorter retention time than α‐tocopherylquinones (α‐TQ), and 2‐ambo‐α‐Toc was completely separated into two peaks; the first peak was RRR‐α‐Toc and the second SRR‐isomer by chiral HPLC connected Chiralcel OD‐H column and Sumichiral OA4100 column. In contrast, of the two peaks of α‐TQ, the first was the SRR‐isomer. We also investigated differences in the distribution of RRR‐ and SRR‐α‐TQ in rat tissues after oral administration of 2‐ambo‐α‐Toc by the above HPLC method. Rats deficient in vitamin E were divided into two groups, control and experimental, and tissues were collected at 3, 6, and 24 h after oral 2‐ambo‐α‐Toc administration. The concentrations of RRR‐ and SRR‐α‐Toc and their quinones in plasma and each tissue were determined. The concentration of SRR‐α‐TQ in plasma and adrenal glands was not significantly different from RRR‐α‐TQ. However, the concentration of SRR‐α‐TQ in liver up to 6 h after oral administration was higher than that of RRR‐α‐TQ, and SRR‐ and RRR‐α‐TQ levels were similar at 24 h after oral administration. Therefore, we may assume that the formation of α‐TQ in vivo was not different between RRR‐ and SRR‐isomer and that it was not affected by the presence of α‐Toc stereoisomers.
The occurrence and possible significance of diacylglyceryl ether lipids in abalone
Authors: Nelson Matthew M. , Nichols Peter D. , Leighton David L.
Published: November 2006

Gonadal and foot tissues of the green abalone, Haliotis fulgens, raised on artificial diets, were analyzed for lipids using thin‐layer chromatography/flame‐ionization detection and gas chromatography‐mass spectrometry (GC‐MS). Diacylglyceryl ether (DAGE) was 0.7% of total lipids in the gonad. The major alkyl constituents of the glyceryl ether diols in the gonad (as % of total diols) were 16∶0 (38%) and 18∶1 (36%). While levels of DAGE in the abalone foot were below flameionization detection limits, glyceryl ether diols from them were detected using the more sensitive GC‐MS procedure. The major diol components in the foot were 18∶0 (39%) and 18∶1 (32%). To our knowledge, this is the first report of DAGE in abalone tissues. Although the precise role of DAGE in abalone remains to be determined, a possible structural role may exist.
3‐thia fatty acid treatment, in contrast to eicosapentaenoic acid and starvation, induces gene expression of carnitine palmitoyltransferase‐II in rat liver
Authors: Madsen Lise , Berge Rolf K.
Published: November 2006

The aim of the present study was to investigate the hepatic regulation and β‐oxidation of long‐chain fatty acids in peroxisomes and mitochondria, after 3‐thia‐ tetradecylthioacetic acid (C14‐S‐acetic acid) treatment. When palmitoyl‐CoA and palmitoyl‐l‐carnitine were used as substrates, hepatic formation of acid‐soluble products was significantly increased in C14‐S‐acetic acid treated rats. Administration of C14‐S‐acetic acid resulted in increased enzyme activity and mRNA levels of hepatic mitochondrial carnitine palmitoyltransferase (CPT)‐II. CPT‐II activity correlated with both palmitoyl‐CoA and palmitoyl‐l‐carnitine oxidation in rats treated with different chain‐length 3‐thia fatty acids. CPT‐I activity and mRNA levels were, however, marginally affected. The hepatic CPT‐II activity was mainly localized in the mitochondrial fraction, whereas the CPT‐I activity was enriched in the mitochondrial, peroxisomal, and microsomal fractions. In C14‐S‐acetic acid‐treated rats, the specific activity of peroxisomal and microsomal CPT‐I increased, whereas the mitochondrial activity tended to decrease. C14‐S‐Acetyl‐CoA inhibited CPT‐I activity in vitro. The sensitivity of CPT‐I to malonyl‐CoA was unchanged, and the hepatic malonyl‐CoA concentration increased after C14‐S‐acetic acid treatment. The mRNA levels of acetyl‐CoA carboxylase increased. In hepatocytes cultured from palmitic acid‐ and C14‐S‐acetic acid‐treated rats, the CPT‐I inhibitor etomoxir inhibited the formation of acid‐soluble products 91 and 21%, respectively. In contrast to 3‐thia fatty acid treatment, eicosapentaenoic acid treatment and starvation increased the mitochondrial CPT‐I activity and reduced its malonyl‐CoA sensitivity. Palmitoyl‐l‐carnitine oxidation and CPT‐II activity were, however, unchanged after either EPA treatment or starvation. The results from this study open the possibility that the rate control of mitochondrial β‐oxidation under mitochondrion and peroxisome proliferation is distributed between an enzyme or enzymes of the pathway beyond the CPT‐I site after 3‐thia fatty acid treatment. It is suggested that fatty acids are partly oxidized in the peroxisomes before entering the mitochondria as acylcarnitines for further oxidation.
Cellular uptake and retention measurements of alkylphosphocholines in the SK‐BR‐3 breast cancer and molt‐4 leukemia cell line using capillary gas chromatography
Authors: Brochez V. , Van Heuverswyn D. , Diniz J. A. De B. N. F. , De Potter C. R. , Van den Eeckhout E. G.
Published: November 2006

The determination of cellular content of octadecylphosphocholine (D‐19391) and hexadecylphosphocholine (HePC, D‐18506), two anticancer agents of the alkylphosphocholine group, using capillary gas chromatography is described. The compounds' cytotoxicity was first determined by the MTI [3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyltetrazolium] assay, being indicative for the concentration used in the uptake and retention measurements. D‐19391 was added to the SK‐BR‐3 breast cancer cell line and HePC to the Molt‐4 leukemia cell line in concentrations of, respectively, 18.6 and 15.0 μM, during a 36‐h incubation period at 37°C, 5% CO2. HePC uptake in the leukemia cells was followed by a 24‐h reversibility test in drug‐free medium. Subsequently, sample clean‐up was performed on a weak cation‐exchange column. For the quantitative analysis, HePC was used as internal standard for the D‐19391 measurements and vice versa. Derivatization of the samples with trimethylsilylbromide was followed by capillary gas chromatographic analysis. From these data we conclude that our uptake results are quite similar with those of a previous study of HePC cellular uptake in the more resistant Coco‐2T colon cancer cell line. Without having investigated the mechanism that underlies the cellular uptake results obtained, our study points to no direct correlation between the compounds' cellular uptake and their cytotoxic effects.
Metabolism of individual fatty acids during infusion of a triacylglycerol emulsion
Authors: Fielding Barbara A. , Samra Jaswinder S. , Ravell Cate L. , Frayn Keith N.
Published: November 2006

The triacylglycerol emulsion Intralipid was infused into six normal subjects to investigate the metabolism of individual fatty acids in subcutaneous adipose tissue and forearm muscle’ by measurement of arteriovenous differences. The composition of plasma nonesterified fatty acids changed steadily after passage through adipose tissue and became similar to that of the emulsion’ reflecting hydrolysis of the Intralipid‐triacylglycerol by lipoprotein lipase’ since endogenous lipolysis (hormone‐sensitive lipase activity plus lipoprotein lipase hydrolysis of verylow density lipoprotein triacylglycerol) was decreased. There was no significant net release of total or individual fatty acids from forearm muscle although there was a tendency for the composition of the fatty acids in forearm venous plasma to change during passage through the tissue to reflect the composition of the emulsion. This may reflect hydrolysis of emulsion particles by lipoprotein lipase situated in capillaries which drain into the forearm vein. The behavior of stearic acid in the plasma nonesterified fatty acid pool was consistently aberrant’ with arterialized concentrations considerably higher than predicted from adipose tissue release’ both before and during Intralipid infusion. We conclude that there are no significant differences in the metabolism of specific fatty acids’ with the exception of stearic acid.
Cholesterol‐derived hydroperoxides in alcoholic liver disease
Authors: Asano Migiwa , Adachi Junko , Ueno Yasuhiro
Published: November 2006

Human liver samples from 33 patients were collected at autopsy (controls’ n=9; fatty liver’ n=12; liver cirrhosis’ n=12)’ and samples homogenized. Lipids extracted with chloroform and methanol were injected into the octyl column of a high‐performance liquid chromatograph with post‐column chemiluminescence. Liquid chromatography‐mass spectrometry was developed to identify 7‐hydroperoxycholest‐5‐en‐3β‐ol (7‐OOH). We found that two cholesterol‐derived hydroperoxides’ 7α‐hydroperoxycholest‐5‐en‐3β‐ol (7α‐OOH) and 7β‐hydroperoxycholest‐5‐en‐3β‐ol (7β‐OOH)’ are present in significantly elevated amounts (12.4 and 25.0 nmol/g tissue’ respectively) in lipid extracts from alcoholic fatty liver’ but not in extracts from alcoholic cirrhotic liver. 7α‐OOH and 7β‐OOH are early intermediates produced during free radical‐mediated cholesterol oxidation and can serve as molecular indicators of chain peroxidative damage in cell membranes. This is the first demonstration of 7α‐OOH and 7β‐OOH accumulations in human liver’ and it is presumed to reflect greater oxidative stress pathology in alcoholic fatty liver.
Regulation of HepG2 cell apolipoprotein B metabolism by the citrus flavanones hesperetin and naringenin
Authors: Borradaile Nica M. , Carroll Kenneth K. , Kurowska Elzbieta M.
Published: November 2006

Our previous studies showed that replacing the drinking water of rabbits fed a casein‐containing diet with either orange juice or grapefruit juice reduced serum low density lipoprotein cholesterol and hepatic cholesteryl ester concentrations. To determine whether the changes observed in rabbits were due to flavonoids present in the juices acting directly on the liver’ the effects of hesperetin and naringenin on net apolipoprotein B (apoB) secretion by HepG2 cells were investigated. These flavanones dose‐dependently reduced net apoB secretion by up to 81% after a 24 h incubation’ while doses of 60 μg/mL reduced net apoB secretion by 50% after 4 h. Coincubation with the proteasome inhibitor’ MG‐132’ did not alter the ability of the flavonoids to reduce net apoB secretion over 4 h’ suggesting that the flavonoid‐induced changes in apoB metabolism were not due to a direct increase in proteasomal activity. However’ the flavonoids were unable to reduce net apoB secretion after 4 h in the presence of oleate’ suggesting that these compounds may interfere with the availability of neutral lipids for lipoprotein assembly. Furthermore’ our 14C‐acetatelabeling studies showed a 50% reduction in cholesteryl ester synthesis in the presence of either flavonoid’ which could account for the reduction in net apoB secretion caused by incubation with these compounds. These in vitro studies suggest that hesperetin and naringenin may’ in part’ reduce net apoB secretion by HepG2 cells by inhibiting cholesteryl ester synthesis and that these compounds are good candidates for further in vivo studies to determine whether they are responsible for the cholesterol‐lowering properties of dietary citrus juices.
Biosynthesis of R‐(+)‐octane‐1’3‐diol. Crucial role of β‐oxidation in the enantioselective generation of 1’3‐diols in stored apples
Authors: Beuerle Till , Schwab Wilfried
Published: November 2006

The biosynthesis of R‐octane‐1’3‐diol and R‐5(Z)‐octene‐1’3‐diol’ two natural antimicrobial agents in apples and pears’ was investigated in stored apples after application of [9’10’12’13‐3H]linoleic acid’ [9’10’12’13’15’16‐3H]linolenic acid’ [1‐14C]linoleic acid’ [U‐14C]oleic acid’ lipoxygenase‐derived metabolites of [9’10’12’13‐3H]linoleic acid’ 13C18‐labeled linoleic acid hydroperoxides’ and 2H‐labeled octanol derivatives. Analysis of the products and quantification of incorporation and labeling pattern were achieved by high‐performance liquid chromatography‐radiodetection’ capillary gas chromatography (GC)‐isotope ratio mass spectrometry’ and GC‐mass spectrometry analysis. Almost all the applied precursors were partly transformed into R‐octane‐1’3‐diol. Linoleic acid derivatives’ still containing the 12’13 cis double bond’ and octanol derivatives oxy‐functionalized at carbon 3 were the most efficient precursors of the 1’3‐diol. The data imply that R‐octane‐1’3‐diol is generated in stored apples in the course of the β‐oxidation from R‐3‐hydroxy‐octanoyl‐SCoA originating from 2‐cis‐octenoyl‐SCoA by enoyl‐CoA hydratase. In an analogous fashion’ R‐5(Z)‐octene‐1’3‐diol is formed from the unsaturated intermediate.
Excess vitamin E decreases canthaxanthin absorption in the rat
Authors: Hageman Susan H. , She Li , Furr Harold C. , Clark Richard M.
Published: November 2006

The recent attention given to the possible role of α‐tocopherol (α‐Toc) and carotenoids in the prevention and treatment of a variety of illnesses resulted in segments of the population increasing their consumption of these nutrient/antioxidants. Once consumed’ α‐Toc and carotenoids are thought to follow the same absorptive pathway and may influence each other's absorption’ particularly when taken in large doses. The purpose of this study was to determine if α‐Toc and the carotenoid’ canthaxanthin (CTX)’ interact during absorption. Rats were intraduodenally infused with corn oil emulsions containing combinations of α‐Toc (0 or 300 pmol/L) and CTX (5’ 10’ 15’ 20 pmol/L) in a 2×4 factorial arrangement. Absorption was determined by measuring recovery of CTX and α‐Toc in the mesenteric lymph. The amount of CTX in the lymph increased significantly with the amount infused into the duodenum. The overall efficiency of CTX absorption from emulsions without α‐Toc averaged 12% with individual animals having a range of 8 to 18%. Efficiency of absorption was not related to concentration of CTX infused. When α‐Toc (300 μmol/L) was added to the oil emulsion’ the absorption of CTX was decreased by at least 50%. Recovery of α‐Toc in the lymph averaged ca. 10% and was not affected by CTX. These results suggest that concurrent consumption of a large dose of α‐Toc may influence carotenoid bioavailability.
Cloning of Δ12‐ and Δ6‐desaturases from Mortierella alpina and recombinant production of γ‐linolenic acid in Saccharomyces cerevisiae
Authors: Huang Yung‐Sheng , Chaudhary Sunita , Thurmond Jennifer M. , Bobik Emil G. , Yuan Ling , Chan George M. , Kirchner Stephen J. , Mukerji Pradip , Knutzon Deborah S.
Published: November 2006

Two cDNA clones with homology to known desaturase genes were isolated from the fungus Mortierella alpina. The open reading frame in one clone encoded 399 amino acids and exhibited Δ12‐desaturase activity when expressed in Saccharomyces cerevisiae in the presence of endogenous fatty acid substrate oleic acid. The insert in another clone contained an open reading frame encoding 457 amino acids and exhibited Δ6‐desaturase activity in S. cerevisiae in the presence of exogenous fatty acid substrate linoleic acid. Expression of the Δ12‐desaturase gene under appropriate media and temperature conditions led to the production of linoleic acid at levels up to 25% of the total fatty acids in yeast. When linoleic acid was provided as an exogenous substrate to the yeast cultures expressing the Δ6‐desaturase activity, the level of γ‐linolenic acid reached 10% of the total yeast fatty acids. Co‐expression of both the Δ6‐ and Δ12‐desaturase cDNA resulted in the endogenous production of γ‐linolenic acid. The yields of γ‐linolenic acid reached as high as 8% of total fatty acids in yeast.
Intermediates and products formed during fatty acid α‐oxidation in cucumber (Cucumis sativus)
Authors: Andersen Borge Grethe I. , Vogt Gjermund , Nilsson Astrid
Published: November 2006

Fatty acid α‐oxidation is an essential metabolic pathway both in plants and in mammals which is still not completely understood. We previously described and purified an α‐oxidation enzyme in cucumber which has been used in the present investigation of the α‐oxidation reaction mechanism. Free fatty acids, and not the CoA thioesters, were found to undergo α‐oxidation in cucumber. 2‐Hydroxy‐ and 2‐oxopalmitic acids were identified as palmitic acid α‐oxidation intermediates by high‐performance liquid chromatography and gas chromatography—mass spectrometry analysis in cucumber subcellular 150,000×gmax pellets obtained by differential centrifugation. Incubation of purified α‐oxidation enzyme with [1‐14C]palmitic acid resulted in the formation of both the above‐described intermediates and the Cn−1 product, pentadecanal, and 14CO2. Besides 14CO2, 14C‐formate was identified as an α‐oxidation product from [1‐14C]palmitic acid in cucumber subcellular fractions. Fe2+ stimulated the 14CO2 and 14C‐formate production, and the addition of ascorbate and 2‐oxoglutarate together with Fe2+ resulted in optimal α‐oxidation activities, suggesting a dioxygenase reaction mechanism, as previously shown in mammals. NADPH and, to a lesser extent, NADH stimulated the total 14C‐formate plus 14CO2 production but had only slight or no effects on 14CO2 production. H2O2 showed concentration‐dependent inhibitory effects, while FAD had neither effect on 14CO2 nor 14CO2 plus 14C‐formate production. The results in the present study demonstrate that an α‐oxidation enzyme in cucumber is capable of oxidizing palmitic acid via 2‐hydroxy‐ and 2‐oxopalmitic acid to produce pentadecanal and CO2. In contrast to the subcellular 150,000×gmax fraction, the purified α‐oxidation enzyme could neither produce formate nor convert 14C‐formate into 14CO2, indicating two possible α‐oxidation routes in cucumber.
Proportion of geometrical hydroperoxide isomers generated by radical oxidation of methyl linoleate in homogeneous solution and in aqueous emulsion
Authors: Wang Xing‐Hua , Ohshima Toshiaki , Ushio Hideki , Koizumi Chiaki
Published: November 2006

The proportion of geometrical hydroperoxide isomers generated by aerobic oxidation of methyl linoleate (18∶2 Me) in either aqueous emulsion consisting of Tris‐HCl buffer (pH 7.4) or in a homogeneous dichloromethane solution was determined to understand the mechanism of lipid oxidation in different reaction systems. Four geometrical isomers were generated after oxidation of 18∶2 Me in dichloromethane: methyl 13‐hydroperoxy‐cis‐9,trans‐11‐octadecadienoate, methyl 13‐hydroperoxy‐trans‐9,trans‐11‐octadecadienoate, methyl 9‐hydroperoxy‐trans‐10,cis‐12‐octadecadienoate, and methyl 9‐hydroperoxy‐trans‐10,trans‐12‐octadecadienoate in the ratios of 1∶4∶1∶4, respectively. The ratios between each isomer did not change until the peroxide value (PV) increased to 58 meq/kg. Oxidation of 18∶2 Me in aqueous emulsion yielded the same geometrical isomers of hydroperoxide. However, the ratios were different: 3∶2∶3∶2 until the PV increased to 110 meq/kg. Predominant (60%) formation of trans,trans hydroperoxide isomers was obtained in the oxidation of a mixture of 18∶2 Me and methyl laurate (12∶0 Me). These results are interpreted to reflect the importance of the concentration of hydrogen atom‐donating equivalents to the kinetic preference for different products. The high effective concentration of hydrogen donors in the oxidation of 18∶2 Me in emulsions favored the formation of the less stable cis,trans isomers. The lower concentration of hydrogen donor in the dichloromethane solution effectively slowed hydrogen donation and led to the strong preference for the more stable trans,trans isomers. This interpretation was further tested by preparing emulsions of 18∶2 Me and 12∶0 Me to dilute concentration of hydrogen‐donating species using the nonhydrogen‐donating 12∶0 Me. Consistent with the proposed hypothesis, the proportion of trans,trans isomers increased as a result of 12∶0 Me addition.
19‐Azasqualene‐2,3‐epoxide and its N‐oxide: Metabolic fate and inhibitory effect on sterol biosynthesis in Saccharomyces cerevisiae
Authors: Milla Paola , Viola Franca , Ceruti Maurizio , Rocco Flavio , Cattel Luigi , Balliano Gianni
Published: November 2006

19‐Azasqualene‐2,3‐epoxide was more inhibitory than the corresponding N‐oxide against 2,3‐oxidosqualene cyclase (OSC) solubilized from Saccharomyces cerevisiae (IC50 7±2 and 25±5 μM, respectively). Both compounds showed a reversible, noncompetitive‐type inhibition on solubilized OSC. Different inhibitory properties between the compounds were especially evident when measuring [14C]acetate incorporation into nonsaponifiable lipids extracted from treated cells. In cells treated with 19‐azasqualene‐2,3‐epoxide at 30 μM, the radioactivity associated with the oxidosqualene fraction, which was negligible in the controls, rose to over 40% of the nonsaponifiable lipids, whereas it remained at a slightly appreciable level in cells treated with the N‐oxide derivative under the same conditions. 19‐Azasqualene‐2,3‐epoxide was also more effective than the N‐oxide as a cell growth inhibitor (minimal concentration of compound needed to inhibit yeast growth: 45 and >100 μM, respectively). The two inhibitors underwent different metabolic fates in the yeast: while 19‐azasqualene‐2,3‐epoxide did not undergo any transformation, its N‐oxide was actively reduced to the corresponding amine in whole and in “ultrasonically stimulated” cells. The N‐oxide reductases responsible for this transformation appear to be largely confined within the microsomal fractions and require NADPH for their activity. A possible relationship between the inhibitory properties of the two compounds and their metabolic fates is discussed.
C2‐ceramide attenuates phenylephrine‐induced vasoconstriction and elevation in [Ca2+]i in rat aortic smooth muscle
Authors: Zheng Tao , Li Wenyan , Wang Jun , Altura Bella T. , Altura Burton M.
Published: November 2006

In the present study, we examined the effects of cell‐permeable C2‐ceramide on contraction of aortic smooth muscle and intracellular free Ca2+ ([Ca2+]i). C2‐ceramide (10−7 to 10−4M) alone did not elicit any significant changes in either basal tension or resting levels of [Ca2+]i in rat aortic smooth muscle. However, C2‐ceramide (10−7 to 10−4 M) attenuated phenylephrine‐induced contractions in isolated rat aortic rings in a concentration‐related manner, and inhibited elevations in [Ca2+]i in cultured rat aortic smooth muscle cells induced by phenylephrine. C2‐ceramide‐induced relaxation was found to be only slightly endothelium‐dependent. However, nitric oxide inhibitors (l‐NNA, l‐NMMA), an inhibitor of prostanoid synthesis (indomethacin), an inhibitor of opiate actions, and several inhibitors of the pharmacologic actions of various vasoactive amines all failed to interfere with the vasorelaxant responses of C2‐ceramide. Three different inhibitors of protein kinase C, when used in a wide concentration range, also failed to interfere with the ceramide‐induced relaxations. Our results suggest that the sphingomyelin‐signaling pathway may play an important regulatory role in arterial wall tone.
The effects of a dietary oxidized oil on lipid metabolism in rats
Authors: Eder Klaus
Published: November 2006

This study was carried out to investigate the effects of a dietary oxidized oil on lipid metabolism in rats, particularly the desaturation of fatty acids. Two groups of rats were fed initially for a period of 35 d diets containing 10% of either fresh oil or thermally treated oil (150°C, 6d). The dietary fats used were markedly different for lipid peroxidation products (peroxide value: 94.5 vs. 3.1 meq O2/kg; thiobarbituric acid‐reactive substances: 230 vs. 7 μmol/kg) but were equalized for their fatty acid composition by using different mixtures of lard and safflower oil and for tocopherol concentrations by individual supplementation with dl‐α‐tocopherol acetate. In the second period which lasted 16 d, the same diets were supplemented with 10% linseed oil to study the effect of the oxidized oil on the desaturation of α‐linolenic acid. During the whole period, all the rats were fed identical quantities of diet by a restrictive feeding system in order to avoid a reduced food intake in the rats fed the oxidized oil. Body weight gains and food conversion rates were only slightly lower in the rats fed the oxidized oil compared to the rats fed the fresh oil. Hence, the effects of lipid peroxidation products could be studied without a distortion by a marked reduced food intake and growth. To assess the rate of fatty acid desaturation, the fatty acid composition of liver and heart total lipids and phospholipids was determined and ratios between product and precursor of individual desaturation reactions were calculated. Rats fed the oxidized oil had reduced ratios of 20∶4n−6/18∶2n−6, 20∶5n−3/18∶3n−3, 20∶4n−6/20∶3n−6, and 22∶6n−3/22∶5n−3 in liver phospholipids and reduced ratios of 20∶4n−6/18∶2n−6, 22∶5n−3/18∶3n−3, and 22∶6n−3/18∶3n−3 in heart phospholipids. Those results suggest a reduced rate of desaturation of linoleic acid and α‐linolenic acid by microsomal Δ4‐, Δ5‐, and Δ6‐desaturases. Furthermore, liver total lipids of rats fed the oxidized oil exhibited a reduced ratio between total monounsaturated fatty acids and total saturated fatty acids, suggesting a reduced Δ9‐desaturation. Besides those effects, the study observed a slightly increased liver weight, markedly reduced tocopherol concentrations in liver and plasma, reduced lipid concentrations in plasma, and an increased ratio between phospholipids and cholesterol in the liver. Thus, the study demonstrates that feeding an oxidized oil causes several alterations of lipid and fatty acid metabolism which might be of great physiologic relevance.