bluuebunny/crossref_metadata_2025_split huggingface dataset:
Linoleic acid metabolism in the spontaneously diabetic rat: Δ6‐desaturase activity vs. product/precursor ratios
Authors: Brown J. E. , Lindsay R. M. , Riemersma R. A. 
Published: November 2006

AbstractThe activity of Δ6‐desaturase of linoleic acid, a rate‐limiting step in the formation of arachidonic acid, is decreased in animal models of severe, uncontrolled diabetes. The aim of the study was to measure the activity of liver microsomal Δ6‐desaturase of spontaneously diabetic BioBreeding/Edinburgh rats receiving subcutaneous insulin daily and of genetically related nondiabetic animals. The activity of Δ6‐desaturase was then compared with indices of activity (plasma lipid fatty acid product/precursor ratios) frequently used in human studies. Diabetic rats treated with insulin had 75±8% of the activity of microsomal Δ6‐desaturase of nondiabetic controls (P<0.05). Insulin withdrawal tended to reduce the activity further (61% of control), although the activity did not differ from insulin‐treated diabetic rats. The ratio of plasma phospholipid or cholesteryl ester γ‐linolenic over linoleic acid was not decreased in insulin‐treated diabetic rats. By contrast, the ratio of γ‐linolenic over linoleic acid of microsomes was almost three‐fold higher in insulin‐treated diabetic rats (P<0.05). The γ‐linolenic over linoleic acid ratio as an index of activity gave inconsistent results in insulin‐deprived rats. The ratio of γ‐linolenic over linoleic acid of cholesteryl esters did not differ between control and diabetic rats, nor did it correlate with microsomal Δ6‐desaturase activity. Furthermore, the index of Δ6‐desaturase activity, derived from the fatty acid composition of microsomal phospholipids, did not correlate with microsomal Δ6‐desaturase activity. Diabetes, even when controlled by regular insulin injections, reduces the metabolism of linoleic acid, but the effect is less than previously published. The fatty acid compositions of plasma and liver microsomal lipids are not reliable indices of Δ6‐desaturase activity in diabetes.
Purification, characterization, and molecular cloning of group I phospholipases A2 from the gills of the red sea bream, Pagrus major
Authors: Iijima Noriaki , Uchiyama Satoshi , Fujikawa Yukichi , Esaka Muneharu 
Published: November 2006

AbstractPhospholipase A2 (PLA2) activity was investigated in various tissues of male and female red sea bream. In both male and female fishes, the specific activity of PLA2 in the gills was 70 times higher than that in other tissues, such as the adipose tissue, intestine, and hepatopancreas. Therefore, we tried to purify PLA2 from the gill filaments of red sea bream to near homogeneity by sequential chromatography on Q‐Sepharose Fast Flow, Butyl‐Cellulofine, and DEAE‐Sepharose Fast Flow columns, and by reversed‐phase high‐performance liquid chromatography. Two minor and one major PLA2, tentatively named G‐1, G‐2 and G‐3 PLA2, were purified, and all showed a single band with an apparent molecular mass of approximately 15 kDa by sodium dodecylsulfate‐polyacrylamide gel electrophoresis. The exact molecular mass values of G‐1, G‐2, and G‐3 PLA2 were 14,040, 14,040 and 14,005 Da, respectively. G‐1, G‐2, and G‐3 PLA2 had a Cys 11 and were all identical in N‐terminal amino acid sequences from Ala‐1 to Glu‐56. A full‐length cDNA encoding G‐3 PLA2 was cloned by reverse transcriptase‐polymerase chain reaction and rapid amplification of cDNA ends methods, and G‐3 PLA2 was found to be classified to group IB PLA2 from the deduced amino acid sequence. G‐1, G‐2, and G‐3 PLA2 had a pH optimum in an alkaline region at around pH 9–10 and required Ca2+ essentially for enzyme activity, using a mixed‐micellar phosphatidylcholine substrate with sodium cholate. These results demonstrate that three group 1 PLA2, G‐1, G‐2, and G‐3 PLA2, are expressed in the gill filaments of red sea bream.
Electron microscopy may reveal structure of docosahexaenoic acid‐rich oil withinSchizochytriumsp
Authors: Ashford A. , Barclay W. R. , Weaver C. A. , Giddings T. H. , Zeller S. 
Published: November 2006

AbstractSchizochytriumsp. is an algae‐like microorganism utilized for commercial production of docosahexaenoic acid (DHA)‐rich oil and dried microalgae for use as a source of DHA in foods, feeds, and nutritional supplements. Electron microscopic analysis of whole cells ofSchizochytriumsp. employing sample preparation by high‐pressure freeze substitution suggests the presence of secondary and tertiary semicrystalline structures of triacylglycerols within the oil bodies inSchizochytriumsp. A fine secondary structure consisting of alternating light‐and darkstaining bands was observed inside the oil bodies. Dark bands were 29±1 Å in width, and light bands were 22±1 Å in width. The tertiary (three‐dimensional) structure may be a multilayered ribbon‐like structure which appears coiled and interlaced within the oil body. In freeze‐fracture photomicrographs,Schizochytriumoil bodies exhibited fracture planes with terraces averaging 52±7 Å in height which could correspond to the combined width of two halves of two light bands and one dark band observed in the high‐pressure freeze substitution photomicrographs. The results suggest that triacyglycerols withinSchizochytriumsp. oil bodies may be organized in a triple chainlength structure. High‐pressure freeze substitution electron micrographs of two other highly unsaturated oil‐producing species of microalgae,Thraustochytriumsp. andIsochrysis galbana, also revealed this fine structure, whereas microalgae containing a higher proportion of saturated oil did not. The results suggest that the staining pattern is not an artifact of preparation and that the triple chain‐length conformation of triacylglycerols inSchizochytriumsp. oil bodies may be caused by the unique fatty acid composition of the triacylglycerols.
Properties of a fluorescent bezafibrate derivative (DNS‐X). A new tool to study peroxisome proliferation and fatty acid β‐oxidation
Authors: Berlot Jean‐Pierre , Lutz Thomas , Malki Mutaspha Cherkaoui , Nicolas‐Frances Val rie , Jannin Brigitte , Latruffe Norbert 
Published: November 2006

AbstractThe first peroxisome proliferator‐activated receptor (PPAR) was cloned in 1990 by Issemann and Green. Many studies have reported the importance of this receptor in the control of gene expression of enzymes involved in lipid metabolic pathways including mitochondrial and peroxisomal fatty acid β‐oxidation, lipoprotein structure [apolipoprotein (apo) A2, apo Clll], and fatty acid synthase. By using radiolabeled molecules, it was shown that peroxisome proliferators bind and activate PPAR. As an alternative method, we developed a fluorescent dansyl (1‐dimethyl‐aminonaphthalene‐5‐sulfonyl) derivative peroxisome proliferator from bezafibrate (DNS‐X), a hypolipidemic agent that exhibits an in vitro peroxisome proliferative activity on rat Fao‐hepatic derived cultured cells. However, until now, the effect of this new compound on the liver of animals and subcellular localization was unknown. In addition to in vivo rat studies, we present a more efficient large‐scale technique of DNS‐X purification. Treating rats (DNS‐X in the diet at 0.3% w/w) for 6 d leads to a hepatomegaly and a marked increase in liver peroxisomal palmitoyl‐CoA oxidase activity. We also developed a method to localize and quantify DNS‐X in tissues or cell compartment organelles. The primarily cytosolic distribution of DNS‐X was confirmed by direct visualization using fluorescence microscopy of cultured Fao cells. Finally, transfection assay demonstrated that DNS‐X enhanced the PPARα activity as well as other peroxisome proliferators do.
Protective effect of phytic acid hydrolysis products on iron‐induced lipid peroxidation of liposomal membranes
Authors: Miyamoto Sayuri , Kuwata Goro , Imai Masatake , Nagao Akihiko , Terao Junji 
Published: November 2006

AbstractBeneficial effects of dietary phytic acid (myo‐inositol hexaphosphate; IP6) have often been explained by its strong iron ion‐chelating ability, which possibly suppresses iron ion‐induced oxidative damage in the gastrointestinal tract. Because phytic acid is hydrolyzed during digestion, this work aimed to know whether its hydrolysis products (IP2′ IP3′, IP4′ and IP5) could still prevent iron ion‐induced lipid peroxidation. Studies using liposomal membranes demonstrated that hydrolysis products containing three or more phosphate groups are able to inhibit iron ion‐induced lipid peroxidation although their effectiveness decreased with dephosphorylation. Similarly, they also prevented iron ion‐induced decomposition of phosphatidylcholine hydroperoxide. These results demonstrate that intermediate products of phytic acid hydrolysis still possess iron ion‐chelating ability, and thus they can probably prevent iron ion‐induced lipid peroxidation in biological systems.
New cyclopentenone fatty acids formed from linoleic and linolenic acids in potato
Authors: Hamberg Mats 
Published: November 2006

Abstract[1‐14C]Linoleic acid was incubated with a whole homogenate preparation from potato stolons. The reaction product contained four major labeled compounds, i.e., the α‐ketol 9‐hydroxy‐10‐oxo‐12(Z)‐octadecenoic acid (59%), the epoxy alcohol 10(S),11(S)‐epoxy‐9(S)‐hydroxy‐12(Z)‐octadecenoic acid (19%), the divinyl ether colneleic acid (3%), and a new cyclopentenone (13%). The structure of the last‐mentioned compound was determined by chemical and spectral methods to be 2‐oxo‐5‐pentyl‐3‐cyclopentene‐1‐octanoic acid (trivial name, 10‐oxo‐11‐phytoenoic acid). Steric analysis demonstrated that the relative configuration of the two side chains attached to the five‐membered ring was cis, and that the compound was a racemate comprising equal parts of the 9(R), 13(R) and 9(S), 13(S) enantiomers. Experiments in which specific trapping products of the two intermediates 9(S)‐hydroperoxy‐10(E), 12(Z)‐octadecadienoic acid and 9(S), 10‐epoxy‐10, 12(Z)‐octadecadienoic acid were isolated and characterized demonstrated the presence of 9‐lipoxygenase and allene oxide synthase activities in the tissue preparation used. The allene oxide generated from linoleic acid by action of these enzymes was further converted into the cyclopentenone and α‐ketol products by cyclization and hydrolysis, respectively. Incubation of [1‐14C]linolenic acid with the preparation of potato stolons afforded 2‐oxo‐5‐[2′(Z)‐pentenyl]‐3‐cyclopentene‐1‐octanoic acid (trivial name, 10‐oxo‐11, 15(Z)‐phytodienoic acid), i.e., an isomer of the jasmonate precursor 12‐oxo‐10, 15(Z)‐phytodienoic acid. Quantitative determination of 10‐oxo‐11‐phytoenoic acid in linoleic acid‐supplied homogenates of different parts of the potato plant showed high levels in roots and stolons, lower levels in developing tubers, and no detectable levels in leaves.
Biased distribution of the branched‐chain fatty acids in ceramides of vernix caseosa
Authors: Oku Hirosuke , Mimura Kunio , Tokitsu Yumi , Onaga Kyoko , Iwasaki Hironori , Chinen Isao 
Published: November 2006

AbstractThe compositions of ester‐ and amide‐linked fatty acids from ceramides of human vernix caseosa were described with emphasis on the distribution of the branched‐chain fatty acid (BCFA). Two novel ceramides were isolated from vernix caseosa in the course of this study: the acylated type of esterified α‐OH‐hydroxyacid/sphingosine ceramide (Cer[EAS]) and nonacylated type of non‐OH fatty acid/hydroxysphingosine ceramide (Cer[NH]). Their chemical structures were identified by nuclear magnetic resonance and chemical procedure. The Cer[EAS] was an acylceramide and consisted of the highest concentrations of ester‐ and amide‐linked BCFA (62 and 67%, respectively). The iso‐ or anteiso‐branching structures of the aliphatic chains were confirmed by the mass spectra of their picolinyl or pyrrolidide derivatives. As a whole, amide‐linked fatty acids of ceramides 1–7 and Cer[NH] were normal types of straight‐chain fatty acids with or without α‐ or ω‐hydroxylation. The BCFA concentrations of amide‐linked fatty acids in these ceramides (ceramides 1–7 and Cer[NH]) were low and less than 10%. The BCFA thus occurred exclusively in a novel acylceramide of Cer[EAS] in the vernix caseosa.
High dietary 18∶3n−3 increases the 18∶3n−3 but not the 22∶6n−3 content in the whole body, brain, skin, epididymal fat pads, and muscles of suckling rat pups
Authors: Bowen Raffick A. R. , Clandinin Michael T. 
Published: November 2006

AbstractThe objective of this study was to test the hypothesis that increasing maternal dietary 18∶3n−3 by decreasing the 18∶2n−6/18∶3n−3 ratio will increase the 18∶3n−3 and 22∶6n−3 content of the whole body, liver, skin (epidermis, dermis, and subcutaneous tissue), epididymal fat pads, and muscles (arms and legs) of 2‐wk‐old rat pups. Sprague‐Dawley dams at parturition were fed semipurified diets containing either a low (18∶2n−6 to 18∶3n−3 ratio of 24.7∶1) or a high (18∶2n−6 to 18∶3n−3 ratio of 1.0∶1) 18∶3n−3 fatty acid content. During the first 2 wk of life, rat pups received only their dams' milk. Fatty acid composition of the pups' stomach contents (dams' milk), whole body, brain, liver, skin, epididymal fat pads, and muscles was determined. The stomach fatty acid composition of 18∶3n−3 reflected the dams' diet. The content of 18∶3n−3 in whole body, brain, liver, skin, epididymal fat pads, and muscles was significantly (P<0.05) greater in rat pups fed the high compared with the low 18∶3n−3 fatty acid diet. The 22∶6n−3 content of the whole body, brain, skin, epididymal fat pads, and muscles was not quantitatively different in rat pups fed either the low or high 18∶3n−3 fatty acid diet. The 20∶5n−3 and 22∶5n−3 content of the whole body, skin, and epididymal fat pads was significantly increased in rat pups fed the high compared with the low 18∶3n−3 fatty acid diet. High content of 18∶3n−3 was found in the skin of rat pups fed either a low or high 18∶3n−3 fatty acid diet. These findings demonstrate that high maternal dietary 18∶3n−3 significantly increases the 18∶3n−3 but not the 22∶6n−3 content of the whole body, brain, skin, epididymal fat pads, and muscles with approximately 39 and 41% of the whole body 18∶3n−3 content being deposited in the skin of suckling rat pups fed either the low or high 18∶3n−3 diet, respectively.
Influence of sources of dietary oils on the life span of stroke‐prone spontaneously hypertensive rats
Authors: Ratnayake W. M. N. , Plouffe L. , Hollywood R. , L'Abbé M. R. , Hidiroglou N. , Sarwar G. , Mueller R. 
Published: November 2006

AbstractIn recent studies, the life span of stroke‐prone spontaneously hypertensive (SHRSP) rats was altered by a variety of dietary fats. It was relatively shorter in rats fed canola oil as the sole source of fat. The present study was performed to find out whether the fatty acid profile and the high content of sulfur compounds in canola oil could modulate the life span of SHRSP rats. SHRSP rats (47 d old, n=23/group) were matched by body weight and systolic blood pressure and fed semipurified diets containing 10% canola oil, high‐palmitic canola oil, low‐sulfur canola oil, soybean oil, high‐oleic safflower oil, a fat blend that mimicked the fatty acid composition of canola oil, or a fat blend high in saturated fatty acids. A 1% sodium chloride solution was used as drinking water to induce hypertension. After consuming the diets for 37 d, five rats from each dietary group were killed for collection of blood and tissue samples for biochemical analysis. The 18 remaining animals from each group were used for determining their life span. The mean survival time of SHRSP rats fed canola oil (87.4±4.0 d) was not significantly different (P>0.05) from those fed low‐sulfur canola oil (89.7±8.5 d), suggesting that content of sulfur in canola oil has no effect on the life span of SHRSP rats. The SHRSP rats fed the noncanola oil‐based diets lived longer (mean survival time difference was 6–13 d, P<0.05) than those fed canola and low‐sulfur canola oils. No marked differences in the survival times were observed among the noncanola oil‐based groups. The fatty acid composition of the dietary oils and of red blood cells and liver of SHRSP rats killed after 37 d of treatment showed no relationship with the survival times. These results suggest that the fatty acid profile of vegetable oils plays no important role on the life span of SHRSP rat. However, phytosterols in the dietary oils and in liver and brain were inversely correlated with the mean survival times, indicating that the differential effects of vegetable oils might be ascribed, at least partly, to their different phytosterol contents.
Dietary fat‐induced suppression of lipogenic enzymes in B/B rats during the development of diabetes
Authors: Cheema S. K. , Clandinin M. Thomas 
Published: November 2006

AbstractThis study was designed to determine the level of inhibition of gene transcription by the reduction in insulin levels upon the onset of diabetes in spontaneously diabetic B/B rats and if reducing the level of polyunsaturated fatty acids (PUFA) in the diet will increase lipogenic enzyme activity. Control (eight animals per group) and spontaneously diabetic B/B male weanling rats (25 animals per group) were fed semipurified diets containing 20% (w/w) fat of either low (0.25) or high (1.0) polyunsaturated to saturated (P/S) fatty acid ratio. Rats were killed at the onset of diabetes [blood glucose level of ≅100 mg/dL (5.55 mM)] and as they became highly diabetic [blood glucose level of ≅400 mg/dL (22.22 mM)]. Total RNA was extracted from liver, and the relative amount of mRNA coding for fatty acid synthase (FAS), acetyl‐CoA carboxylase, malic enzyme, pyruvate kinase, and phosphoenolpyruvate carboxykinase was determined. Liver enzyme activities were also measured. The mRNA levels for FAS, acetyl‐CoA carboxylase, and malic enzyme decreased compared to control animals. The mRNA level for pyruvate kinase decreased at the onset of diabetes as compared to control animals. Feeding animals the low P/S diet treatment elevated the level of mRNA and lipogenic enzyme activity compared to animals fed the high P/S diet treatment, suggesting that the effect of PUFA on lipogenic enzymes is through a direct effect on gene expression.
Lipid composition of erythrocytes and thrombocytes of a subantarctic seabird, the king penguin
Authors: Fayolle Christine , Leray Claude , Ohlmann Philippe , Gutbier Geneviève , Cazenave Jean‐Pierre , Gachet Christian , Groscolas René 
Published: November 2006

AbstractPhospholipid (PL) compositions and fatty acid (FA) patterns of PL were determined in the erythrocytes and blood thrombocytes of a seabird, the king penguin, living in the subantarctic area and feeding on prey rich in n−3 polyunsaturated FA. Results were compared between birds in three different physiological states (breeding and molting adults, chicks) to those reported for other birds. In erythrocytes, the ratios of cholesterol to PL and of sphingomyelin to phosphatidylcholine (PC) were lower than in other birds. The PL distribution was similar to those previously reported in the hen and pigeon. In contrast to other birds, cardiolipin levels were unexpectedly high (4%). Very long chain n−3 FA were abundant (13–27%) in phosphatidylethanolamine (PE), phosphatidylserine and PC, probably in relation to the natural diet of these birds. Among n−3 FA, 22∶6n−3 was the most abundant in all PL (2−20%), whereas the highest levels of arachidonic acid were observed in PE (14%). In thrombocytes, the PL distribution and FA composition of the main PL (PC, PE) differed from those of erythrocytes, and in particular, levels of n−3 FA (9–12%) were 1.5–2 times lower. The highest levels of arachidonic acid were found in phosphatidylinositol (24%). The lipid profile of penguin erythrocytes could contribute to the efficiency of blood circulation and oxygen delivery in microvascular beds, thus favoring diving capacity of these animals. Our observations do not support the hypothesis of a common origin of avian thrombocytes and erythrocytes.
Metabolism of 1‐acyl‐2‐oleoyl‐sn‐glycero‐3‐phosphoethanolamine in castor oil biosynthesis
Authors: Lin Jiann‐Tsyh , Lew Karen M. , Chen Jennifer M. , Iwasaki Yugo , McKeon Thomas A. 
Published: November 2006

AbstractWe have examined the role of 2‐oleoyl‐PE (phosphatidylethanolamine) in the biosynthesis of triacylglycerols (TAG) by castor microsomes. In castor microsomal incubation, the label from 14C‐oleate of 1‐palmitoyl‐2‐[1‐14C]oleoyl‐sn‐glycero‐3‐phosphoethanolamine is incorporated into TAG containing ricinoleate. The enzyme characteristics, such as optimal pH, and the effect of incubation components of the oleoyl‐12‐hydroxylase using 2‐oleoyl‐PE as incubation substrate are similar to those for 2‐oleoyl‐PC (phosphatidylcholine). However, compared to 2‐oleoyl‐PC, 2‐oleoyl‐PE is a less efficient incubation substrate of oleoyl‐12‐hydroxylase in castor microsomes. Unlike 2‐oleoyl‐PC, 2‐oleoyl‐PE is not hydroxylated to 2‐ricinoleoyl‐PE by oleoyl‐12‐hydroxylase and is not desaturated to 2‐linoleoyl‐PE by oleoyl‐12‐desaturase. We have demonstrated the conversion of 2‐oleoyl‐PE to 2‐oleoyl‐PC and vice versa. The incorporation of label from 2‐[14C]oleoyl‐PE into TAG occurs after its conversion to 2‐oleoyl‐PC, which can then be hydroxylated or desaturated. We detected neither PE‐N‐monomethyl nor PE‐N,N‐dimethyl, the intermediates from PE to PC by N‐methylation. The conversion of 2‐oleoyl‐PE to 2‐oleoyl‐PC likely occurs via hydrolysis to 1,2‐diacyl‐sn‐glycerol by phospholipase C and then by cholinephosphotransferase. This conversion does not appear to play a key role in driving ricinoleate into TAG.
Effects of passive smoking on the regulation of rat aortic cholesteryl ester hydrolases by signal transduction
Authors: Maehira Fusako , Zaha Fusako , Miyagi Ikuko , Tanahara Asami , Noho Ayano 
Published: November 2006

AbstractThe effects of exogenous oxidative stress due to passive smoking on cholesteryl ester (CE)‐metabolizing enzymes and their regulatory kinases were examined by exposing rats to cigarette smoke (CS) for a 1‐h period twice a day for 8, 12, or 20 wk. An oxidatively modified low density lipoprotein (Ox‐LDL) with a high lipid peroxide was identified in three CS groups after all three exposure periods. The rat aortic acid and neutral CE hydrolases (ACEH and NCEH) were activated to similar extents by both cAMP‐dependent protein kinase (PKA) and protein kinase C (PKC) in the presence of their respective cofactors. The aortic PKC activity in the three CS groups exhibited significant reductions of 72, 84, and 75% as compared with the respective controls, which coincided with the reductions in the ACEH activities (86, 71, and 80%, respectively), whereas the PKA activities increased to 121, 197, and 252% in the three CS groups, respectively. Reflecting the increase of the PKA activity, the NCEH activity exhibited increases of 112% at 8 wk and 140% until 12 wk of exposure and decreased by 50% of the control value at 20 wk of exposure, suggesting inactivation of NCEH itself. The activation of acyl‐CoA:cholesterol O‐acyl‐transferase activity was associated with an increase of free cholesterol in aorta. The vitamin E diet prevented the formation of Ox‐LDL and the oxidative inactivation of most enzymes, especially PKC, until 12 wk, but was less effective by 20 wk. The oxidative inactivation of PKC, particularly its activated form that translocated to the membrane fraction, was confirmed in the in vitro exposure to active oxygen generators at an optimal concentration; this inactivation was prevented by catalase and superoxide dismutase. These results suggested that the formation of Ox‐LDL and alterations in CE‐metabolizing enzymes caused by passive smoking could contribute to a twofold increase in the aortic CE content, thereby contributing to one of the mechanisms for atherosclerosis associated with smoking.