bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of clofibrate on cholesterol metabolism in rats treated with polychlorinated biphenyls
Authors: Nakagawa M. , Shimokawa T. , Noguchi A. , Ishihara N. , Kojima S. 
Published: November 2006

AbstractSerum and hepatic cholesterol content in rats treated with polychlorinated biphenyls (PCBs, KC‐400) were increased compared to those of control rats. This increase of cholesterol content was reduced to control level by simultaneous administration of ethyl p‐chlorophenoxyisobutyrate (CPIB). Also, when lecithin‐cholesterol acyltransferase (LCAT) (EC. 2.3.1.43) activity was expressed as the net cholesterol esterification, the acyltransferase activity in rats treated with PCBs was elevated, while the elevated acyltransferase activity was brought to control level by simultaneous administration of CPIB. On the other hand, the amount of bile of rats treated with CPIB, PCBs and PCBs‐CPIB was increased, but free and total cholesterol content in bile of these treated rats was decreased to 40–60% of those of control rats. Moreover, cytochrome P‐450 content in liver microsomes of rats treated with CPIB, PCBs and PCBs‐CPIB was increased. At the same time, cholesterol‐metabolizing activity in liver microsomes of rats treated with CPIB, PCBs and PCBs‐CPIB also was elevated. Similar results were obtained for drug metabolizing (aniline hydroxylation and aminopyrine N‐demethylation) activity. In addition, the amount of bile acids excreted from rats treated with CPIB, PCBs and PCBs‐CPIB was increased compared to that of control rats.These results suggest that hypercholesterolemia induced by oral ingestion of PCBs is recovered by CPIB treatment and that this hypocholesterolemic effect of CPIB may be related partly to the elevation of hepatic mixed function oxidase activity for cholesterol catabolism.
Localization of fatty acid double bonds by gas chromatography of intermediate aldehydes as 1,3‐dioxane
Authors: Lakshminarayana Gollamudi , Cornwell David G. 
Published: November 2006

AbstractA semi‐micro quantitative method has been developed for the determination of double bond positions in unsaturated fatty acid methyl esters differing in position, number of double bonds and chain length. This method involves ozonolysis in methylene chloride in the presence of 1,3‐propanediol, reduction of the hydroperoxides with dimethyl sulfide and conversion of aldehyde and aldester fragments to stable dioxanes, followed by gas chromatographic analysis under programmed temperature. Propanediol acts as a proton donor for the generation of hydroperoxides as well as a reactant for the formation of dioxanes. All the steps are carried out in a culture tube without any transfers. The absence of unoxidized ester and unreduced hydroperoxide or ozonide has been shown by thin layer chromatography. The method has been tested with pure esters and their binary mixtures. Experimental values for mole percentage composition in the mixtures agreed with the actual values. This method enabled us to isolate and estimate malondialdehyde for the first time as a stable bis‐dioxane derivative.
Effects of a (n−3) polyunsaturated fatty acid‐deficient diet on profiles of serum vitellogenin and lipoprotein in vitellogenic trout (Salmo gairdneri)
Authors: Frémont L. , Léger C. , Petridou B. , Gozzelino M. T. 
Published: November 2006

AbstractDuring the 6 months of vitellogenesis, 3‐year‐old female trout (Salmo gairdneri) were fed either an enriched (E) or an (n−3) polyunsaturated fatty acid (PUFA)‐deficient (D) diet; serum vitellogenin (VG) and lipoproteins (d<1.21 g/ml) were analyzed at the third month of vitellogenesis (September) and at ovulation (December). The serum content of high density lipoproteins (HDL), the major protein class, maintained a mean value of 1500 mg/dl at both stages and with both diets. On the contrary, very low density lipoproteins (VLDL) were 90% higher during vitellogenesis than at spawning time, whereas excess vitellogenin circulated at this period (6580 mg/dl serum with diet E). The diet deficient in (n−3) lowered serum vitellogenin content by 16% in September and by 26% in December. The degree of (n−3) PUFA incorporation moderately decreased in low density lipoproteins (LDL) and in HDL with the (n−3)‐deficient diet. The effect was more pronounced for 20∶5. On the other hand, essential 22∶6 was incorporated into vitellogenin at the same rate in September as in December with diet E (23% and 25%, respectively), whereas after a 3‐month deficiency, the percentage fell to 12%; this percentage rose again to 19% at spawning time. These findings show that, although stored (n−3) PUFA were not exhausted after a 6‐month dietary deficiency, the incorporation of essential fatty acids (EFA) into vitellogenin during the early stages of oogenesis was low, suggesting changes in egg composition that may influence hatching.
The biosynthesis of n‐[2H7] fatty acids byArthrobacter globiformis from [U‐2H15] octanoic acid
Authors: White Robert H. 
Published: November 2006

AbstractThe principal fatty acids present whenArthrobacter globiformis is grown on a glycine medium free of normal fatty acids were found to be the C15 and C16 anteiso fatty acids; only a small amount of the normal fatty acids (C14 and C16) were present. Cells grown on the same medium but supplemented mented with 0.1 mg/ml [U‐2H15]octanoic acid were found to contain an increased amount of the normal fatty acids and these fatty acids were found to be labeled with 7 deuteriums. I concluded that the octanoic acid is degraded by β‐oxidation in these cells to [U‐2H7] butyryl‐CoA, which then competes with 2‐methylbutyryl‐CoA for the initiation of fatty acid biosynthesis.
Daily variations of the biosynthesis and composition of fatty acids in rats fed on complete and fat‐free diets
Authors: de Gómez Dumm I. N. T. , de Alaniz M. J. T. , Brenner R. R. 
Published: November 2006

AbstractThis report describes the daily changes in fatty acid composition and fatty acid desaturation in rats feeding on a complete diet and a fat‐free diet successively. Rats on a complete diet showed a good homeostasis in the percentage of fatty acid in plasma, with a possible palmitic acid rhythm, but the fat‐free diet initiated an essential fatty acid‐deficient pattern in a few hours. The light‐dark period in animals feeding on a complete diet motivates a feeding rhythm that causes changes in linoleic and arachidonic acids in the whole liver and microsomes that are related to Δ6 and Δ5 desaturase activities. The patterns of Δ6 and Δ5 desaturase changes were different. Linoleic acid intake during the dark periods (complete diet feeding) caused a decrease of Δ6 desaturase activity and the activation of Δ5 desaturation that led to an increase of arachidonic acid biosynthesis. The feeding of a fat‐free diet eliminated the rhythm observed in linoleic and arachidonic acid composition in the liver and changed the desaturase rhythms. The Δ9 desaturase activity in the liver also showed a daily rhythm in the complete‐diet period that disappeared with the change to a fat‐free diet, while the activity increased markedly. A negative correlation existed between the percentage of linoleic acid in the liver and the Δ9 desaturase activity. However, no correlation was found between Δ9 desaturase activity and the percentage of 16∶1 and 18∶1 in the complete‐diet period.
Effect of different amino acid diets on δ5, δ6 and δ9 desaturases
Authors: Peluffo Raul O. , Nervi Anibal M. , Gonzalez Maria S. , Brenner Rodolfo R. 
Published: November 2006

AbstractA high‐protein diet with 45% calories from casein increased δ6 desaturase activity in rat‐liver microsomes. High‐protein diets with 45% calories from a synthetic mixture of amino acids in the same proportion as casein decreased the δ9 desaturase, slightly increased the δ5 desaturase and greatly increased δ6 desaturase activities compared with a high‐carbohydrate diet. The elimination of phenylalanine and tyrosine from the synthetic mixtures of amino acids increased the δ6 desaturase activity. Massive amounts of phenylalanine or tyrosine in the diet inhibited δ6 desaturase activity. Tyrosine and phenylalanine may, by conversion to tyrosine, decrease the activity of the δ6 desaturase.
The effects oftrans fatty acids on fatty acyl Δ5 desaturation by human skin fibroblasts
Authors: Rosenthal Miriam D. , Doloresco Mark A. 
Published: November 2006

AbstractThe effectiveness of different fatty acids as inhibitors of fatty acyl Δ5 desaturation activity in human skin fibroblasts has been investigated. When incubated with 2.25 μM [14C] eicosatrienoate (20∶3ω6) in otherwise lipid‐free medium, these cells rapidly incorporate the radiolabeled fatty acid into cellular glycerolipids and desaturate it to produce both [14C] arachidonate and [14C] docosatetraenoate. The Δ5 desaturation activity can be enhanced by prior growth of the cells without serum lipids. Elaidate (9t–18∶1) is a potent inhibitor of Δ5 desaturation whiletrans‐vaccenate (11t–18∶1) is virtually without effect. Oleate and linoleate are only mildly inhibitory. Linoelaidate (9t, 12t–18∶2) is more inhibitory than linoleate but significantly less effective than elaidate. The effects of elaidate can be readily overcome by increasing the concentration of exogenous eicosatrienoate. Studies with a variety oftrans monounsaturates of differing chain lengths indicate that the ω9trans fatty acids are potent inhibitors of Δ5 desaturation, while ω7trans fatty acids are relatively ineffective. Intact human fibroblasts could thus be important in characterizing novel fatty acids as selective inhibitors of arachidonate synthesis in vivo.
Effect of protein depletion on the VLDL triacylglycerol secretion and apoprotein synthesis by the perfused liver from pregnant rats
Authors: Tournier H. , Yaryour G. , Mercuri O. , De Tomás M. E. 
Published: November 2006

AbstractThe effect of protein depletion in the pregnant rat on the polyunsaturated fatty acid incorporation into very low density lipoproteins (VLDL) has been investigated. The apoprotein pattern of these particles was determined. In in vivo experiments the amounts of serum and liver triacylglycerol were determined. VLDL were isolated and their apo C concentration calculated. In in vitro experiments the radioactivity of [3H] leucine incorporated into VLDL apoproteins was measured. The results show that protein depletion during pregnancy promotes a drastic increase in serum and liver triacylglycerol. The VLDL isolated from these animals show an increase in the triacylglycerol/protein ratio and a decrease in their content of apo C. Meanwhile, a significant reduction in the [3H]leucine incorporation into apo C peptides by the perfused liver of protein depleted rats was detected. On the other hand, protein deprivation did not affect labeled linoleic and arachidonic acid incorporation into triacylglycerol of the newly secreted VLDL. Taking these results together, let us deduce that a defective VLDL is secreted by the liver of the protein depleted pregnant rats. The abnormal composition of these particles may influence its normal metabolism through their effects on lipoprotein lipase and this fact could affect the normal supply of polyunsaturated fatty acids to the fetus.
Occurrence of a 22∶2 nonmethylene interrupted dienoic fatty acid and its seasonal distribution among lipids and tissues of the fresh water bivalveDiplodon delodontus from an isolated environment
Authors: Irazu C. ‐E. , Pollero R. J. , Brenner R. R. 
Published: November 2006

AbstractRealatively high levels of a non‐methylene‐interrupted dienoic fatty acid were detected in the freshwater molluscDiplodon delodontus. The (7,13) 22∶2 NMID fatty acid was separated from total fatty acids by TLC, and its structure was determined by GLC and reductive ozonolysis. Its seasonal distribution was investigated in different tissues and lipids of the mollusc. High concentrations of this acid were found in polar lipids. The absence of the 22∶2 NMID fatty acid in the lipids of plankton and sediment in the same habitat suggests that it may be biosynthesized by themollusc. Possible synthesis and functions of the NMID fatty acids are discussed.
The effects of dietary cholesterol on blood and liver polyunsaturated fatty acids and on plasma cholesterol in rats fed various types of fatty acid diet
Authors: Huang Y. S. , Manku M. S. , Horrobin D. F. 
Published: November 2006

AbstractMale rats were fed on a fat‐free diet for 8 weeks and then switched to diets containing 10% hydrogenated coconut oil (HCO), safflower oil (SFO) or evening primrose oil (EPO). Half of each group was also given 1% of cholesterol in the diet. After 5 further weeks, plama, red cell and liver fatty acids were measured in the various lipid fractions. Plasma and liver cholesterol also were estimated. In almost all fractions and on all three diets, feeding cholesterol led to accumulation of the substrates of desaturation reactions and to deficits of the products of these reactions. The results were consistent with inhibition of Δ‐6, Δ‐5 and Δ‐4 desaturation of n−6 essential fatty acids. Since the diets were deficient in n−3 fatty acids, levels were very low but were also consistent with inhibition of desaturation. In contrast, cholesterol had relatively less consistent effects on 20∶3n−9, suggesting that desaturation of n−9 fatty acids was less inhibited. Plasma cholesterol levels rose sharply in the HCO and SFO groups but not at all in the EPO group. EPO contains the product of Δ‐6 desaturation, 18∶3n−6, suggesting that conversion of linoleic acid to 18∶3n−6 and possibly to further metabolites may be important for the cholesterol‐lowering effect of polyunsaturates.
Lipid and fatty acid characterization and metabolism in the sea anemonePhymactis clematis (Dana)
Authors: Pollero Ricardo J. 
Published: November 2006

AbstractNeutral lipid, phospholipids and fatty acids of the sea anemonePhymactis clematis from the south‐west Atlantic were characterized and quantified in spring and autumn. Neutral lipids predominated over phospholipids in both seasons. Triacylglycerol and diacylglycerol ethers were the major lipids. In spring, an increase of esterified sterols was noted. The major fatty acids found were 22∶5ω3, 20∶5ω3 and 16∶0. The sea anemones were also incubated in vivo with either [1‐14C]linoleate or [1‐14C] α‐linolenate for 2 hr. Isotope incorporation into lipids and their transformations into higher fatty acids were examined. Both precursors were incorporated into the lipids, mainly in triacylglycerols and mono‐acylglycerols, while α‐linolenate was also incorporated into phospholipids. The radioactive linoleate was elongated to 20∶2, 22∶2 and 24∶2 fatty acids, but not desaturated to 18∶3ω6. α‐Linolenate was desaturated by Δ6 desaturase to 18∶4ω3. The specificity of Δ6‐desaturase is discussed.
Effects of purified eicosapentaenoic acid on arachidonic acid metabolism in cultured murine aortic smooth muscle cells, vessel walls and platelets
Authors: Morita I. , Saito Y. , Chang W. C. , Murota S. 
Published: November 2006

AbstractThe effects of highly purified eicosapentaenoic acid (97% pure) on the arachidonic acid cascade in isolated murine vascular cells and platelets were studied. The incorporation of eicosapentaenoic acid was not as active as that of arachidonic acid in platelets. The ratio of incorporation of eicosapentaenoic acid to arachidonic acid into platelet phospholipids was about 0.7. Analysis of the phospholipid fractions of platelets after labeling with14C‐eicosapentaenoic acid and14C‐arachidonic acid revealed that the incorporation of14C‐eicosapentaenoic acid into the phosphatidylinositol fraction is significantly less than that of14C‐arachidonic acid, while the incorporation of both fatty acids into other phospholipid fractions was almost the same. On the other hand, no significant difference between either fatty acid in incorporation rate, kinetics or distribution in cellular phospholipids was found in cultured aortic smooth muscle cells. Following treatment with eicosapentaenoic acid, cells produced less prostacyclin from endogenous arachidonic acid than did control cells. This was not due to the decrease in fatty acid cyclooxygenase activity, but rather, due to the decrease in arachidonic acid content in cellular phospholipids. In addition, eicosapentaenoic acid was neither converted to prostaglandin I3 by the vascular cells nor to thromboxane A3 by platelets. Furthermore, similar results were also obtained by in vivo experiments in which rats were fed with eicosapentaenoic acid enriched diet.
Effects of streptozotocin‐induced diabetes on microsomal long‐chain fatty acyl‐CoA synthetase and hydrolase
Authors: Dang A. Q. , Faas F. H. , Carter W. J. 
Published: November 2006

AbstractStreptozotocin‐induced diabetes significantly decreased rat liver microsomal long‐chain fatty acyl‐CoA (LCA‐CoA) hydrolase. The decrease was observed using either palmitoyl‐CoA (35 per cent, p<0.01) or oleoyl‐CoA (23 per cent, p<0.01) as the substrate for the enzyme. Under the same conditions, diabetes did not significantly alter activity of LCA‐CoA synthetase. Daily subcutaneous injections of protamine zinc insulin (10–12 units/day) into the diabetic rats returned their blood glucose to normal but only partially corrected the LCA‐CoA hydrolase activity and did not effect LCA‐CoA synthetase activity. The decreased LCA‐CoA hydrolase and the unchanged LCA‐CoA synthetase activities in the diabetic rat liver were interpreted as factors that may contribute to elevation of fatty acyl‐CoA levels in the diabetic liver.
Fatty liver caused by chronic alcohol ingestion is prevented by dietary supplementation with pyruvate or glycerol
Authors: Rao G. Ananda , Riley Diana E. , Larkin Edward C. 
Published: November 2006

AbstractEarlier studies showed that the fatty liver, caused by feeding rats the Lieber‐DeCarli alcohol diet for four weeks, was prevented if the diet was supplemented with dihydroxyacetone (22 g/l), pyruvate (22 g/l) and riboflavin (2.2 g/l). In the present study, we observed that fatty liver was prevented if the alcohol diet was supplemented with glycerol and lactate (22 g/l each) and riboflavin (2.2 g/l). Hence, the prevention of alcoholic fatty liver by the dietary supplementation with dihydroxyacetone and pyruvate may not be related to their capacity to serve as hydrogen acceptors and to oxidize NADH produced during ethanol metabolism. When rats were fed the alcohol diet supplemented with either glycerol or pyruvate, the hepatic triglyceride (TG) levels were similar to those in rats pair‐fed a Lieber‐DeCarli control diet in which alcohol was replaced with an isocaloric amount of dextrins. Therefore, the prevention of fatty liver does not require the simultaneous presence of several supplements. Dietary dihydroxyacetone or riboflavin did not reduce alcoholic fatty liver. Supplementation of the ethanol diet with isocaloric amounts of lactate or glucose, instead of pyruvate, did not abolish the development of fatty liver but caused a marked reduction in the hepatic TG levels. Animals fed the alcohol diet consumed only small amounts of carbohydrate for long periods of time. Since the inclusion of glucose or its metabolites in the alcohol diet fed to rats caused a marked decrease in the liver TG content, it is likely that the production or prevention of fatty liver is related to carbohydrate metabolism.
Changes in the structure of soybean triacylglycerols due to heat
Authors: Yoshida Hiromi , Alexander J. C. 
Published: November 2006

AbstractCommercially refined soybean oil was heated at 180 C for 50, 70 or 100 hr with aeration. The triacylglycerol fractions separated from the oils by column chromatography on silica gel were fractionated further by silicic acid thin layer chromatography (TLC), and species compositions were determined by argentation TLC and lipase hydrolysis. There was a decrease in the absolute amounts of the triacylglycerols with longer heating periods, such as 21% for 50 hr and 42% for 100 hr. Relatively large changes occurred in the proportion of the molecular species of the triacylglycerols during heating; there was an increase in the more saturated species, 1–4 double bonds, and a decrease in species containing 5–7 double bonds. Although these changes occurred in the percentage of each triacylglycerol species, the positional distribution of the fatty acids in the 2‐position remained virtually unchanged throughout heating. Oleic and linoleic acids were commonly found in the 2‐position of the acylglycerol moiety, whereas most of the palmitic and stearic acids favored esterification in the 1‐ and 3‐positions. The results indicate that unsaturated fatty acids located in the 2‐position are protected significantly from thermal oxidative decomposition.
The effects of streptozotocin diabetes on tissue specific lipase activities in the rat
Authors: Nomura Takahide , Hagino Yasumichi , Gotoh Minehiro , Iguchi Akihisa , Sakamoto Nobuo 
Published: November 2006

AbstractFasting in normal rats produced a fall in hepatic triglyceride lipase (H‐TGL) activity as well as lipoprotein lipase (LPL) activities of adipose tissue and psoas minor muscle. On the other hand, LPL activities of heart and diaphragm were not decreased by fasting; the former, in fact, was increased significantly. Changes in tissue specific lipase activity caused by withdrawal of insulin from insulin‐treated diabetic animals paralleled in direction the changes induced by starvation of normal rats. Furthermore, it was shown in the present paper that the tissue specific lipase activity of diabetic rats became stuck in the starve phase of the starve‐feed cycle regardless of dietary intake. The changes of the tissue specific lipase activities, especially of liver, adipose tissue and heart, appeared to coincide with those of plasma insulin levels. These results strongly suggest that the tissue specific lipase system is under hormonal regulation by insulin. Streptozotocin diabetes produced hypertriglyceridemia. The possible mechanism of the hypertriglyceridemia in diabetic animals was discussed in connection with the role of the tissue specific lipase system in the serum triglyceride metabolism.
The effects of hypophysectomy and testosterone treatment on the composition and metabolism of testicular lipids
Authors: Marzouki Zohair M. H. , Coniglio John G. 
Published: November 2006

AbstractThe effects of hypophysectomy and of testosterone administration on lipid composition and metabolism of rat testicular tissue have been investigated. Increased concentrations of triacylglycerols and cholesterol were observed in testes of hypophysectomized compared to control (non‐hypophysectomized) rats on the eighth day posthypophysectomy. Administration of testosterone maintained the concentrations of these lipids at about normal levels. The concentration of phospholipids was not affected by the hypophysectomy. Incorporation of14C from 1‐[14C] linoleate into testicular lipids was determined 24 hours after intratesticular injection. In hypophysectomized compared to control rats there was more14C in C 16∶0, C 20∶2 and C 20∶3 and less14C in C 20∶4 and C 22∶4 of both phospholipids and triacylglycerols. After intratesticular injection of 1‐[14C] eicosatrienoate there was more14C in C 16∶0 and C 20∶3 and less14C in C 20∶4 and C 22∶4 of both phospholipids and triacylglycerols of hypophysectomized compared to control rats. Intratesticular injection of 1‐[14C]‐arachidonate resulted in less14C incorporation in C 22∶4 in testes of hypophysectomized than in those of control rats. Treatment with testosterone did not affect the metabolism of any of the14C‐substrates. These results indicate that the testicular desaturation of C 20∶3 to arachidonate, requiring a Δ5 desaturase, is inhibited by hypophysectomy and that testosterone by itself may control the concentrations of some testicular lipid classes but not the metabolism of the polyenoic acids.