bluuebunny/crossref_metadata_2025_split huggingface dataset:
The inhibitory guanine nucleotide‐binding protein Gi2α induces and potentiates adipocyte differentiation
Authors: Høvik Kjerstin E. , Wu Pengfei , Gordeladze Jan O. 
Published: November 2006

AbstractThe 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

AbstractAlthough 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

AbstractDuring 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

AbstractRecently 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

AbstractWe 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

AbstractGonadal 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

AbstractThe 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

AbstractThe 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

AbstractThe 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

AbstractHuman 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

AbstractOur 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

AbstractThe 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

AbstractThe 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

AbstractTwo 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.