bluuebunny/crossref_metadata_2025_split huggingface dataset:
Glucagon and N6,O2′‐dibutyryl adenosine 3′∶5′‐monophosphate inhibition of lipogenesis and phosphofructokinase activity of hepatocytes from meal‐fed rats
Authors: Ochs Raymond S. , Harris Robert A. 
Published: December 2006

AbstractGlucagon and N6,O2′‐dibutyryl adenosine 3′∶5′‐monophosphate (dibutyryl cyclic AMP) inhibit net glucose utilization, lactate plus pyruvate accumulation and fatty acid synthesis by isolated hepatocytes prepared from meal‐fed rats. A crossover in the metabolite profile of the glycolytic intermediates occurs between fructose‐6‐phosphate and fructose‐1,6‐bisphosphate, suggesting either inhibition of phosphofructokinase or activation of fructose diphosphatase, or both. Direct assay of the enzymes in cell‐free extracts of the hepatocytes indicates that dibutyryl cyclic AMP inhibits phosphofructokinase but has no effect upon fructose diphosphatase. The assay for phosphofructokinase was modified by the use of ITP in place of ATP for the phosphate donor as the ATP‐linked assay is complicated by an apparent time‐dependent activation of the enzyme. These findings strongly suggest that cyclic AMP inhibition of phosphofructokinase explains in part cyclic AMP inhibition of aerobic glycolysis and lipogenesis by rat liver hepatocytes.
Effect of dietary fatty acid composition on the biosynthesis of unsaturated fatty acids in rat liver microsomes
Authors: Kurata Norimasa , Privett O. S. 
Published: December 2006

AbstractA study was made of the influence of semisynthetic diets of low and high unsaturation on the fatty acid composition and desaturation‐chain elongation enzymatic activity of the liver microsomal fractions of male Sprague‐Dawley rats of different ages. Groups of rats were fed 5 or 20% coconut oil (CO), or a 5 or 20% mixture of corn and menhaden oils (3∶7) (CME) from weaning to 100 wk of age. Growth rate and food consumption were measured during this period in which animals were sacrificed at 36, 57, 77 and 100 wk of age. Both the level and composition of the dietary fat supplements produced marked effects on the fatty acid composition of the liver microsomal lipids. In general, the fatty acid composition of the microsomal fractions reflected that of the dietary fat and was more unsaturated with the higher level of fat fed. The rate of conversion of linoleic to arachidonic acid in assays performed in vitro with liver microsomal preparations from animals of the different groups also showed marked differences. The 6‐desaturase‐chain elongation activity was higher in the 5% than 20% group and corresponded to the essential fatty acid (EFA) status of the animals in these groups as represented by the triene‐tetraene ratio of the microsomal lipid. The relationship of the 6‐desaturase activity to fatty acid composition of the microsomal lipid indicated that if varied directly with the level of 20∶3ω9, 18∶1 and 16∶1 and was inhibited by arachidonic acid. The activity of the 6‐desaturase enzyme system was lowest in the liver microsomal fraction obtained from the animals fed the CME diets and appeared to be suppressed by the high levels of 20∶5 and 22∶6 that accumulated in the microsomal lipid. Accordingly, the levels of arachidonic acid were lower in the microsomal lipid of these groups than those of the corresponding CO groups in spite of a greater abundance of linoleic acid in the diet. The data suggest that the activity of the 6‐desaturase‐chain elongation system is regulated by the fatty acid composition of the microsomal lipid as influenced by the composition of the dietary fat.
Lipids of myocardial membranes: Susceptibility of a fraction enriched in sarcolemma to hydrolysis by an exogenous mammalian phospholipase A2
Authors: Owens K. , Pang D. C. , Franson R. C. , Weglicki W. B. 
Published: December 2006

AbstractA myocardial membrane fraction enriched in sarcolemma was used to determine the susceptibility of the lipids to hydrolysis by a phospholipase A2 from granulocytes. After incubation (37 C, pH 7.0, 5 mM Ca2+) with the phospholipase A2 for 30 min, a more than 3‐fold increase in unesterified fatty acids was found (up to 47 nmol/mg protein; P<0.001) relative to a control incubated without phospholipase A2 or Ca2+. This included a 10‐fold increase in the arachidonic acid content (up to 42 mol %) and at least a 7‐fold increase in lysophosphatidylethanolamine (up to 7.4 mol% total phospholipid‐P). However, the exogenous phospholipase did not augment the quantity of lysophosphatidylcholine produced by endogenous phospholipases in the presence of Ca2+ (5 mM). These results demonstrate the in vitro susceptibility of phospholipids of myocardial membranes, particularly phosphatidylethanolamine, to the neutral‐active, Ca2+‐dependent phospholipase A2 from granulocytes. This work may be relevant to myocardial inflammation and tissue damage during ischemia, where heterolytic injury of the myocardium may occur subsequent to the accumulation of granulocytes.
Comparison of pyrrolidides with other amides for mass spectral determination of structure of unsaturated fatty acids
Authors: Andersson B. Å. , Heimermann W. H. , Holman R. T. 
Published: December 2006

AbstractAmides of unsaturated fatty acids give mass spectra which indicate the locations of the double bonds. A survey of several amides of oleic acid was made to evaluate which amide might be most suitable for routine use in elucidation of structure. Methods of preparation of several amides of oleic acid are presented with mass spectral and gas chromatographic data. Tertiary amides have most easily interpretable mass psectra which indicate the position of the double bond in the fatty acid chain. The pyrrolidide is advantageous for fatty acid gas liquid chromatography and mass spectrometry analyses because it can be prepared easily in high yield on a microscale, it is volatile enough for gas liquid chromatographic separations, and it has a simple and easily interpretable mass spectrum which indicates the structure.
Induction of essential fatty acid deficiency in mouse brain: Effects of fat deficient diet upon acyl group composition of myelin and synaptosome‐rich fractions during development and maturation
Authors: Sun G. Y. , Go J. , Sun A. Y. 
Published: December 2006

AbstractA fat‐deficient diet was initiated in mice before birth and at different ages during development and maturation. The induction of an essential fatty acid deficiency in brain was most effective when the deficient diet was initiated prenatally. With increasing time on the deficient diet, there was an increase in 20∶3(n−9) and a decrease in 20∶4(n−6) in the phosphoglycerides of subcellular brain fractions. The highest ratio of 20∶3(n−9) to 20∶4(n−6) observed was 1.5 for both diacyl and alkenylacyl glycerophosphorylethanolamines in the synaptosome‐rich fraction from mice on the deficient diet from before birth to 7 months of age. The acyl groups of brain ethanolamine plasmalogens are quite susceptible to alteration by the fat‐deficient diet. Elongated products of 20∶3(n−9), tentatively identified as 22∶3(n−9) and 22∶5(n−9), also were present in brain during essential fatty acid deficiency. These fatty acids were preferentially linked to the alkenylacyl glycerophosphorylethanolamines. It further was observed that, even when the deficient diet was initiated after maturation, similar changes in fatty acid composition occurred in both myelin and synaptosomerich fractions, but at a slower rate. For mice on the deficient diet from 12–18 months of age, the highest ratio of 20∶3(n−9) to 20∶4(n−6) was 0.6 for the alkenylacyl glycerophosphorylethanolamines from the myelin.
Characterization of two steroidal olefins in nonfat dry milk
Authors: Flanagan Vincent P. , Ferretti Aldo , Ruth John M. 
Published: December 2006

AbstractTwo steroidal olefins were isolated from the hydrocarbon fraction of a n‐hexane extract of nonfat dry milk. They were characterized as 24‐methyl‐Δ2‐cholestene (Δ2‐campestene) and 24‐ethyl‐Δ2‐cholestene (Δ2‐sitostene) by gas chromatography, mass spectrometry, and synthesis.
Brain cholesterol: XVI. Incorporation of different precursors into baboon tissue sterol
Authors: Kabara Jon J. 
Published: December 2006

AbstractThe relative order of incorporation of 1‐C14‐acetate and 2‐3H‐acetate into tissue cholesterol was similar. Short term fasting tended to decrease incorporation of acetate into liver and adrenal sterol. Other tissues, particularly neural, had the same or showed an increased incorporation. This relative order of incorporation found for acetate was different when U‐14C‐glucose was used. Cholesterol values from neural tissue after glucose were greater than non‐neural sterol values.
The structures of the principal glycerolipids of pig liver
Authors: Hunter M. L. , Christie W. W. , Moore J. H. 
Published: December 2006

AbstractThe lipid composition of pig liver has been determined. The principal glycerolipids, i.e., triglycerides, phosphatdyl choline, phosphatidyl ethanolamine and phosphatidyl inositol, were isolated and the positional distribution of fatty acids in each determined by stereospecific analysis procedures. Previous results for the triglycerides were confirmed, while the phospholipids were similar in structure to those found in most other animal livers. The triglycerides were separated into simpler molecular species by combinations of silver nitrate thin layer chromatography and high temperature gas liquid chromatography, but the proportions found did not agree well with those calculated assuming a 1‐random, 2‐random, 3‐random arrangement. The phospholipids were hydrolyzed with phospholipase C and converted to diglyceride acetates that were fractionated into simpler molecular species by the same procedures as were used with triglycerides. Highly specific fatty acid combinations were found in molecular species, and these specificities were very similar to those reported in similar lipids from the livers of such disparate species as the rat and chicken.
Identification of 18‐oxo‐9,10‐epoxystearic acid, a novel compound in the cutin of young apple fruits
Authors: Kolattukudy P. E. 
Published: December 2006

Abstract18‐Oxo‐9,10‐epoxystearic acid was identified in the cutin of young apple fruits by hydrogenolysis with LiAlH4, deuterolysis with LiAlD4, CrO3 oxidation of deuterated product followed by reduction with LiAlH4 and mass spectrometry of the products.
Characterization of plasma lipoproteins in swine with different propensities for obesity
Authors: Etherton Terry D. , Kris‐Etherton P. M. 
Published: December 2006

AbstractYorkshire (lean) and Ossabaw (obese) swine ca. one year of age were used to characterize the quantity and composition of plasma lipoproteins in animals with markedly different adiposity. While lean swine weighed more (175 vs 88 kg for obese), they had less backfat than obese swine (2.64 vs 5.97 cm; P<0.05). Fasting plasma triacylglycerol (Tg) and cholesterol (CH) levels were elevated in obese swine. Swine plasma lipoproteins were fractionated into very low density lipoprotein (VLDL; d<1.006), low density lipoprotein1 (LDL1; d=1.019–1.063), low density lipoprotein2 (LDL2; d=1.063–1.09), and high density lipoprotein (HDL; d=1.09–1.21) by density ultracentrifugation. Obese VLDL‐Tg, CH and protein (Pr) were elevated more than 2‐fold. VLDL from obese swine were 2‐fold larger than VLDL from lean swine. No alterations in LDL1 or LDL2 composition were observed. HDL‐Tg, CH, Pr and phospholipid levels were significantly higher in obese swine. Plasma and VLDL‐Tg levels were highly correlated with backfat thickness (r=0.67 and r=0.73, respectively). These was a positive correlation between adiposity and HDL‐CH as well as VLDL‐Tg and HDL‐CH. These data indicate that (a) there are marked alterations in swine plasma lipoprotein composition between lean and obese swine; (b) that swine plasma lipoprotein levels may be useful parameters in estimating body composition; and (c) that HDL‐CH is positively correlated with adiposity in swine.
Selectivity in incorporation, utilization and retention of oleic and linoleic acids by human skin fibroblasts
Authors: Rosenthal Miriam D. 
Published: December 2006

AbstractFetal human fibroblasts were grown in culture medium containing 10% fetal bovine serum supplemented with [1‐14C] linoleate or [1‐14C] oleate. At all concentrations of exogenous fatty acids, the incorporation of oleate was greater than that of linoleate. With increased medium fatty acid concentrations, linoleate in triacylglycerol (TAG) could be increased from 13 to 75% of the total incorporated; at each concentration, relatively more linoleate than oleate was in TAG. When the cells were exposed to exogenous oleate/linoleate mixtures, the composition of the mixture determined the extent of incorporation of both fatty acids. When the mixture was primarily linoleate, scarce oleate was used preferentially for phospholipids (PL); no such specificity for scarce linoleate was observed. Addition of exogenous fatty acids resulted in a shift of previously incorporated14C fatty acids from phospholipid into TAG; retention of oleate in PL was greater than that of linoleate. Incorporation of oleate into phospholipids was also higher than that of linoleate from exogenous fatty acid mixtures which were 80% saturated. It is suggested that normal human fibroblasts have adapted to the low levels of exogenous polyunsaturated fatty acids in culture media by increased use of oleate in phospholipid. Even when the cells aresupplemented with linoleate, the preferential use of oleate in phospholipid groups is retained.
Origins of the cholesterol in milk
Authors: Long Carol A. , Patton Stuart , McCarthy Robert D. 
Published: December 2006

AbstractStudies were conducted to investigate the origin of milk cholesterol in the ruminant. In the first experiment, [1‐14C] sodium acetate was infused into one side of the udder of a lactating goat via the teat canal whereas in the second, [1,2‐3H] cholesterol was injected intravenously and concurrently with a [14C] acetate intrammamary infusion. In both experiments, blood and milk samples were collected at intervals for 6 days postinjection. Maximum unesterified cholesterol specific activity (sp act) in whole milk appeared at 78 hr after intravenous injections of3H cholesterol and within 3–7 hr after infusion of [14C]acetate. Virtually all the tritium in milk was associated with unesterified cholesterol. The sp act of14C‐labeled cholesterol was only 20% of gland‐synthesized decanoic acid. Decanoic acid is known to be completely synthesized in the mammary gland, and, like cholesterol, acetate is its precursor. The results indicate that, although some milk cholesterol is synthesized in the mammary gland, it is derived principally from serum cholesterol. The data show also that serum cholesterol equilibrates with membrane cholesterol of the lactating cell prior to its secretion in milk.
Distribution of deuterium‐labeledcis‐andtrans‐12‐octadecenoic acids in human plasma and lipoprotein lipids
Authors: Emken E. A. , Dutton H. J. , Rohwedder W. K. , Rakoff Henry , Adlof R. O. , Gulley R. M. , Canary J. J. 
Published: December 2006

AbstractTriglycerides containingcis‐ andtrans‐12‐octadecenoic acid (12c‐18∶1 and 12t‐18∶1) andcis‐9‐octadecenoic acid (9c‐18∶1) labeled with deuterium were fed to 2 young adult male subjects. These fatty isomers each contained a different number of deuterium labels, which allowed mass spectrometric analysis to distinguish among them after they were fed as a mixture. This approach results in a direct comparison of the absorption and distribution of these 3 monoenoic acids into blood plasma and lipoprotein lipids. Plasma lipid data indicated that all phospholipid fractions selectively incorporate 12c‐18∶1 and 12t‐18∶1 in preference to 9c‐18∶1. Discrimination against 12c‐18∶1 and 12t‐18∶1 compared to 9c‐18∶1 was found in the plasma neutral lipids, with a strong discrimination against 12t‐18∶1 incorporation into the cholesteryl ester fraction. Considerable reduction in the percentage of linoleic and arachidonic acid was observed when 12–18∶1 isomers were incorporated in plasma triglyceride, phosphatidylcholine and sphingomyelin samples. Chylomicron lipid analyses indicated that all isomers were well absorbed. Variation was observed in the relative distribution of 12c‐18∶1, 12t‐18∶1 and 9c‐18∶1 between the very low density, low density and high density lipoprotein lipid classes. No desaturation of 12c‐18∶1 to linoleic acid was detected.
Incorporation of fatty acids into phospholipids in L cells stimulated by antibody
Authors: Shearer William T. , Ulrich Robert G. 
Published: December 2006

AbstractBinding antibodies to surface membranes stimulated incorporation of fatty acids (FA) into phospholipids of L cells. Antibodies stimulated at least a 3.4‐fold greater incorporation of arachidonic acid into phosphatidylinositol than into any other class of phospholipid when compared on a molar basis (p<0.003). This enhanced incorpoation was selective, depending on the character of the FA, because antibodies stimulated the incorporation of arachidonic acid at least 2.4‐fold more than oleic acid, palmitic acid or stearic acid (p<0.001). Surprisingly, an antibody‐stimulated incorporation of palmitic acid into sphingomyelin (SM) was at least 2.2‐fold greater than that into any other class of phospholipid (p<0.001) and the antibody‐stimulated incorporation of palmitic acid into SM was at least 60‐fold greater than that of arachidonic acid, stearic or oleic acid (p<0.001). Nontoxic doses of ethylenediamine tetraacetic acid (EDTA), dexamethasone, 4‐bromophenacylbromide and indomethacin inhibited the antibody‐stimulated incorporation of arachidonic acid into cellular phospholipids, principally phosphatidylinositol (PI), and similarly inhibited the antibody stimulation of DNA synthesis. We conclude that when antibody binds to surface antigens on L cells, a rapid and selective incorporation of fatty acids into certain cellular phospholipids occurs, possibly mediated by calcium‐dependent phospholipases. Degradation products of arachidonic acid, i.e., prostaglandins, may be important in these antibody stimulation events, as well. These early changes in phospholipid metabolism may serve as an important signal or mechanism for the subsequent stimulation of DNA synthesis in L cells.
Linoleate hydroperoxides are cleaved heterolytically into aldehydes by a Lewis acid in aprotic solvent
Authors: Gardner H. W. , Plattner R. D. 
Published: December 2006

AbstractTreatment of isomeric methyl linoleate hydroperoxides with a Lewis acid, BF3, in anhydrous ether led to a carbon‐to‐oxygen rearrangement that caused cleavage into shorter‐chain aldehydes. Methyl (9Z,11E)‐13‐hydroperoxy‐9,11‐octadecadienoate afforded mainly hexanal and methyl (E)‐12‐oxo‐10‐dodecenoate, whereas methyl (10E,12Z)‐9‐hydroperoxy‐10,12‐octadecadienoate cleaved into 2‐nonenal and methyl 9‐oxononanoate. The 2 aldehydes obtained from each hydroperoxide isomer were uncharacteristic of the complex volatile profile usually obtained by β‐scission of oxy radicals derived from homolysis of the hydroperoxide group. Rather, the reaction resembled the one catalyzed by the plant enzyme, hydroperoxide lyase.
Urinary prostaglandin E2 and vasopressin excretion in essential fatty acid‐deficient rats: Effect of linolenic acid supplementation
Authors: Hansen Harald S. , Jensen Benny 
Published: December 2006

AbstractThree groups of weanling male rats were fed on a fat‐free diet for 13 weeks. One group received only the fat‐free diet (FF rats), the other 2 groups received the fat‐free diet and a daily supplement of 2 energy% ethyl linoleate ([n−6] rats), or 2 energy% ethyl linolenate ([n−3] rats). Urinary excretion of prostaglandin E2 (PGE2), immunoreactive arginine vasopressin (iA VP), and kallikrein were determined. PGE2 was quantitated with a radioimmunoassay having 4.9% cross‐reactivity with prostaglandin E3 (PGE3). After 4 weeks on the diet, water consumption and urinary iAVP excretion increased significantly in the FF rats and the (n−3) rats compared with the (n−6) rats. Urinary PGE2 excretion was the same for all 3 groups during the first 10 weeks; thereafter it decreased in FF rats and (n−3) rats compared with the (n−6) rats. There was no difference in urinary PGE2 excretion between the FF rats and the (n−3) rats, even though large differences were found in the percentage of arachidonic acid (20∶4[n−6]), icosapentaenoic acid (20∶5[n−3]), and icosatrienoic acid (20∶3[n−9]) of total kidney fatty acids as well as of kidney phosphatidylinositol fatty acids. Fractionation of urine extracts on high performance liquid chromatography with radioimmunoassay detection indicated that (n−3) rats excreted very little PGE3, if any. Urine output followed the same pattern, as did urinary PGE2 excretion. Urinary kallikrein was estimated at week 12 only. It was found to be significantly lower in FF rats and (n−3) rats. Increased water consumption and increased urinary iAVP excretion seem to be early symptoms (after 4 weeks) of EFA deficiency, whereas decreased urine output and decreased urinary PGE2 excretion occur much later (after 10 weeks). Two energy% linolenate supplementation to a fat‐free diet did not change the appearance of any of the measured EFA‐deficiency symptoms except for a slightly improved growth rate. There was no evidence of a significant urinary PGE3 excretion in spite of an extreme enrichment of kidney lipids with 20∶5(n−3). It is suggested that urinary PGE2 is derived from precursors delivered from an arachidonic acid pool, which is rather resistant to restriction in dietary linoleate.
Changes in renal phospholipid fatty acids in diabetes mellitus: Correlation with changes in adenylate cyclase activity
Authors: Clark Daniel L. , Hamel F. G. , Queener Sherry F. 
Published: December 2006

AbstractMale Sprague‐Dawley rats made diabetic with alloxan (37.5 mg/kg) or streptozotocin (65 mg/kg) were killed after 3–6 weeks of disease; renal tissues were studied for phospholipid content and for fatty acid composition of the phospholipids. No consistent change was noted in total phospholipid content nor in the proportion of various phospholipids in diabetics. However, diabetic animals showed a consistent reduction of arachidonic acid content in phosphatidylcholine (PC) and phosphatidylethanolamine in whole renal cortex, plasma membranes purified from renal cortex, and in isolated glomeruli. Associated with the fall in arachidonic acid was a rise in linoleic acid in the samples studied. Insulin therapy returned the fatty acid profiles to normal. These results are similar to patterns observed in other diabetic tissues and suggest that diabetes is associated with generalized changes in cell membranes. That these structural changes may have functional significance is suggested by demonstrated alterations in the temperature‐dependence of adenylate cyclase in renal plasma membranes of diabetic animals. Adenylate cyclase is thought to be intimately associated with PC in plasma membranes, a phospholipid showing significant changes in fatty acid content in diabetes (unsaturation index 165±2 for normals, 147±5 for diabetics). Na+,K au+‐ATPase which is thought to be primarily associated in vivo with phosphatidylinositol (PI), shows no change in apparent energy of activation in diabetes. The fatty acid content of PI is minimally altered in diabetes, and the unsaturation index is unchanged.