bluuebunny/crossref_metadata_2025_split huggingface dataset:
The influence of urea on lipogenesis in renal papillae of rats
Authors: Bojesen Inge N. 
Published: December 2006

AbstractThe osmolality has been determined for the papillary interstitial fluids obtained from the isolated papillae of rats in different states of water balance. Hypertonic buffers for in vitro experiments were prepared by addition of urea to regular Krebs‐Ringer phosphate buffers (340 mosmol/kg H2O) since urea is the most changeable solute of the renal papillary tissue in response to external influences. The effect of such hypertonic buffers on papillary lipogenesis was very pronounced. The fatty acid synthesis from acetate decreased by a factor of 7–9 in response to increased osmolality from 340 to 1370 mosmol/kg H2O. In the physiological range of osmolalities (500–1800 mosmol/kg H2O), the de novo synthesis of papillary glycerolipids from glucose decreased by a factor of ca. 5. A possible specific inhibitory effect of hypertonic buffers on the pentose phosphate cycle was studied with a negative result. It is concluded that the addition of urea causes a decrease of total energy metabolism in the tissue.
Cigarette smoke affects lipolytic activity in isolated rat lungs
Authors: Hartiala Jaakko , Viikari Jorma , Hietanen Eino , Toivonen hannu , Uotila Pekka 
Published: December 2006

AbstractIsolated perfused rat lungs liberated fatty acids at a rate of 15 μmol/hr during perfusion of triglyceride‐rich medium through the pulmonary vascular bed. About 80% of this activity seemed to result from lipoprotein lipase and 20% to hormone‐sensitive lipase. Ventilation of the lungs with cigarette smoke instead of air during the perfusion reduced fatty acid liberation by 23%. Pre‐exposure of rats to cigarette smoke for either 1 or 10 days did not cause significant changes in lung lipolytic activity compared to sham‐exposed controls.
Comparative studies on the fatty acid composition of moderately and extremely thermophilic bacteria
Authors: Oshima Mieko , Miyagawa Akihisa 
Published: December 2006

AbstractThe fatty acids of three strains of extremely thermophilic bacteria and three strains of moderately thermophilic bacteria were examined by gas liquid chromatography. All the thermophiles contained straight, iso, and ante‐iso branched fatty acids. Iso C17∶0 acid was abundant in both the moderately thermophilic strains (10–33%) and the extremely thermophilic strains (50–61%). The pair of fatty acids iso C15∶0 and iso C17∶0 was the predominant pair in both the moderately (34–64%) and extremely (76–87%) thermophilic strains. The pair of fatty acids ante‐iso C15∶0 and ante‐iso C17∶0 was present in larger amount in moderately (25–34%) than in extremely (8.5–15%) thermophilic strains. No hydroxy cyclopropane, or unsaturated fatty acids were found. One extreme thermophile,Flavobacterium thermophilum HB‐8 was grown at 6 different culture temperatures from 49–82 C, and the changes of its fatty acid composition were studied. The ratios of iso C17∶0/iso C15∶0 and ante‐iso C17∶0/ante‐iso C15∶0 were much greater at higher culture temperatures, indicating chain elongation.
Influence of the polar group on interactions between phospholipids and sterols in monolayers. Rapid decomposition of phosphatidylethanolamines and cholesterol in monolayers at pH 11.9
Authors: Ghosh D. , Lyman R. L. , Tinoco J. 
Published: December 2006

AbstractPressure‐area curves were obtained for monolayers of pure lipids or mixtures of lipids in order to investigate the effect of different polar groups upon interactions between molecules of various structures. Cholest‐4‐ene‐3‐one and cholestan‐3‐one were measured alone and in mixtures with di 16∶0‐lecithin, and 16∶0–18∶1‐lecithin, 16∶0–18∶3‐lecithin, and 16∶0–20∶4‐lecithin. All lecithin films were somewhat condensed by the ketones, but much less so than by cholesterol. Cholesterol was measured alone and with either di 16∶0 phosphatidylethanolamine (PE) or rat liver phosphatidylethanolamine at pH 2.0, 5.4 and 11.9. Cholesterol condensed the natural PE at pH 2.0 and 5.4, but not the di 16∶0 PE. At pH 11.9, both cholesterol and PE were chemically unstable in monolayers. The strong interaction of cholesterol with mixed phosphatidylethanolamines in monolayers suggests that cholesterol may also interact strongly with PE in membranes, of which PE are important components.
Fatty acid composition of symbiotic zooxanthellae in relation to their hosts
Authors: Bishop David G. , Kenrick Janette R. 
Published: December 2006

AbstractGymnodinoid dinoflagellate symbionts, commonly referred to as zooxanthellae, are widely distributed among marine invertebrates. It has been assumed that they represent only one species,Gymnodinium microadriaticum. The fatty acid composition of total lipids and galactolipids of zooxanthellae isolated from 8 species of corals, 3 species of clams and a foraminiferan have been analyzed and found to vary according to the host. For example, the content of eicosapentaenoic acid in clam zooxanthellae monogalactosyldiacylglycerol was less than 2%, whereas in the same lipid from coral zooxanthellae, the content ranged from 9 to 22%. Corresponding values for the acid in digalactosyl‐diacylglycerol were 1–8% from clam zooxanthellae and 23–40% from coral zooxanthellae. Coral zooxanthellae monogalactosyldiacylglycerol contain higher levels of octadecatetraenoic acid than are found in digalactosyldiacylglycerol, whereas the reverse is true in clam zooxanthellae. The fatty acid composition of the lipids of an axenic culture of zooxanthellae isolated from the clamTridacna maxima are similar to those of cells freshly isolated from the host. The results suggest either that the host is capable of affecting the fatty acid metabolism of the symbiont or that different strains of zooxanthellae occur in corals and clams.
Bile acids: LXI. Synthesis and properties of conjugates of 5α‐bile acids
Authors: Shaw Roger , Elliott William H. 
Published: December 2006

AbstractAllo bile acids and their taurine‐ and glycine‐conjugates were synthesized by modification of existing procedures. Their chromatographic and spectral properties were investigated and compared with the 5β‐analogs. Some of the naturally occurring 5α‐ and 5β‐conjugates were separable by high performance liquid chromatography via straight‐phase (Corasil II column) or reverse‐phase systems (μBondapak/C18 column), though unsuccessful with thin layer or gas liquid chromatography. Differences between the C‐5 epimers in the infrared and proton magnetic resonance spectra could be attributed to the configurations at the A/B ring junction and the configuration of the 3‐hydroxyl group. The calcium salts of the allo compounds were generally less soluble in water than the 5β‐isomers.
Occurrence of unusual hexadecenoate fatty acids in hepatoma lipids
Authors: Wood Randall , Lee Theresa 
Published: December 2006

AbstractCis‐hexadecenoates isolated from rat liver and hepatoma 7288CTC lipids were analyzed for positional isomers by ozonolysis and capillary gas liquid chromatography. In addition to the Δ6, Δ7, Δ9 and Δ11 isomers found in both tissues, the hepatoma neutral and polar lipids contained relatively high percentages of Δ12 and Δ14 hexadecenoates that were virtually absent from liver. The occurrence of these unusual fatty acids may result from an error in lipid metabolism in the hepatoma.
Temperature‐dependent deacylation of molecular species of phosphatidylcholine by microsomal phospholipase A2 of thermally acclimated rainbow trout,Salmo gairdneri1
Authors: Neas N. P. , Hazel J. R. 
Published: December 2006

AbstractUsing the ratios of kinetic parameters, V/Km, the deacylation of different molecular species of 1‐palmitoyl,2‐acyl phosphatidylcholine via microsomal phospholipase A2 (PLA2) was studied in liver tissue of thermally acclimated rainbow trout (Salmo gairdneri). In general, PLA2 from fish acclimated to cold temperatures showed an order of preference for the acyl moieties of 18∶1>18∶1>18∶2>18∶0. Trout acclimated to warm temperatures generally preferred 18∶0 PC, but the actual order of preference depended on the temperature of the assays and the presence of endogenous lipids in the enzyme preparation. At 5 C, the particulate (microsomal) enzyme preferred 18∶0>18∶2>18∶1, but a lipid‐free preparation of the enzyme preferred 18∶2>18∶0>18∶1. At 20 C, particulate enzyme preferred 18∶1>18∶0>18∶2 but purified enzyme preferred 18∶0>18∶2>18∶1. Thus, assay temperature and the presence of microsomal lipids had a greater effect on PLA2 from fish acclimated to warm temperatures than fish acclimated to cold temperatures. The substrate preference of PLA2 is discussed with reference to the previously observed changes in membrane fatty acid composition that occur with thermal acclimation in rainbow trout.
Double‐bond patterns of fatty acids and alcohols in steer and human meibomian gland lipids
Authors: Nicolaides N. , Santos Evelyn C. , Papadakis Konstantine 
Published: December 2006

AbstractOzonolysis studies of the monoenes of the fatty chain types in lipids of steer meibomian gland excreta (meibum) have confirmed earlier structural assignments based on gas liquid chromatography (GLC) retention data and have assisted in assigning complete structures to a group of recently identified ω‐hydroxy fatty acids. The ω‐hydroxy acids include straight‐chain monoenoic acids (85%), saturated anteiso and iso acids (13%), monoenoic acids of the latter group (1%) and, finally, saturates of the normal monoenoic acids (1%). All the fatty chains of meibum can be biosynthesized by a unified process of chain buildup to primary chain lengths of 12∶0–20∶0 for the straight evens, with 16∶0 predominating, 13∶0–21∶0 for the straight odds with 17∶0 predominating, i16∶0 to i28∶0 for the iso and ai17∶0 to ai29∶0 for the anteiso chain types; then Δ9 desaturation of each of these chain types; and finally chain elongation of 1–10 C2 units. Some chain degradation may also occur. The meibum lipid components involved are unsubstituted fatty acids, α‐OH fatty acids, ω‐OH fatty acids, fatty alcohols and some other lipid components incompletely characterized. The carbon skeletons are straight even, straight odd, iso and anteiso except that the α‐OH fatty acids are only straight even and straight odd and these chains are not elongated. All fatty chains are almost entirely saturated and monoenoic, the polyenes occurring in only trace amounts. Biosynthesis of the fatty chains of human meibum evidently occurs similarly, except that considerably more 18∶0 than 16∶0 fatty acids are built up by the fatty acid synthetase, before desaturation and extension.
Singlet oxygen in copper‐catalyzed lipid peroxidation in erythrocyte membranes
Authors: Ding Ai‐Hao , Chan Phillip C. 
Published: December 2006

AbstractLipid hydroperoxide was generated in human erythrocyte membranes by irradiation with near ultraviolet (UV) light in the presence of a photosensitizer, hematoporphyrin, but no production of 2‐thiobarbituric acid‐reactive materials (malonaldehyde and its precursors) was detected. Incubation of the irradiated membranes with CuSO4 led to increased levels of hydroperoxide and formation of malonaldehyde. Hydroperoxides were essential for initiating the Cu(II)‐catalyzed peroxidation as no significant activity was observed with nonirradiated membranes and Cu(II) unless an organic peroxide, either t‐butyl hydroperoxide or cumene hydroperoxide, was added. Catalytic activity was also found with Fe(II), but not with other metal ions tested. The peroxidation catalyzed with Cu(II) was partially inhibited by several singlet oxygen quenchers but was not affected by superoxide dismutase, catalase or OH• radical scavengers. The possible involvement of singlet oxygen in the Cu(II)‐catalyzed peroxidation reaction was further supported by a 3‐fold enhancement of malonaldehyde production in D2O.
Fatty acid desaturase specificity in tetrahymena
Authors: Conner Robert L. , Burtness Barbara , Ferguson Karen A. 
Published: December 2006

AbstractThe ciliate,Tetrahymena, was provided a supplement of the fatty acid [1‐14C] 18∶2Δ6,9. After a period of growth the cells were claimed, the lipids extracted, the polar lipids recovered and the mild alkali‐labile fatty acid methyl esters generated. The fatty acids were resolved by high pressure liquid chromatography (HPLC), the 18∶3Δ6,9,12 (γ‐linolenic acid) was recovered and its identity verified by high pressure liquid chromatography (HPLC), gas liquid chromatography (GLC), hydrogenation and oxidation. Fifty‐three percent of the cell‐associated label was found in γ‐linolenic acid; thus, a Δ12 fatty acid desaturase converts the 6,9 octadecadienoic acid to the 6,9,12 derivative. No carboxyl or methyl terminus restriction appears on Δ9 monoenoic or dienoic fatty acid desaturation in this cell as is found in higher plants and animals.
Phospholipid synthesizing enzymes of dermatophytes III. Glycerol kinase of dermatophytes
Authors: Kasinathan C. , Khuller G. K. 
Published: December 2006

AbstractGlycerol kinase, the key enzyme for glycerol use in phospholipid synthesis, was identified in cytosolic fractions of 2 dermatophytes,Microsporum gypseum andEpidermophyton floccosum. Ammonium sulfate was observed to activate and stabilize this enzyme in both dermatophytes. Two pH optima, 8.0 and 10.5, were observed for both dermatophyte enzymes. Glycerol kinase fromM. gypseum was purified up to 33‐fold with a 225% recovery by ammonium sulfate precipitation and gel filtration. The molecular weight of the enzyme was ca. 4.5×105. It had 2 pH optima of 8.0 and 10.5. The enzyme had Km values of 0.35 mM and 2.3 mM for glycerol and ATP. Reactivity of the enzyme for various nucleotides was ATP>TTP>GTP>ITP=CTP=UTP. Kinetic studies showed the enzyme to catalyze the reaction by the ping‐pong mechanism. Fructose 1,6‐bisphosphate and glucose‐6‐phosphate inhibited the enzyme competitively, whereas glucose was not inhibitory.
Quantitative determination of Tri‐, Di‐,monooleins and free oleic acid by the thin layer chromatography‐flame lonization detector system using internal standards and boric acid impregnated chromarod
Authors: Tatara Takako , Fujii Tomiko , Kawase Tokuzo , Minagawa Motoi 
Published: December 2006

AbstractThe separation conditions for hydrolysates of triglycerides by lipase and their quantitative determination are discussed for a thin layer chromatography‐flame ionization detector system utilizing internal standards. The complete separation of glyceride hydrolysis mixtures (triolein 1,3‐diolein, 1,2‐diolein, 1‐monoolein and oleic acid) was achieved on a 3% boric acid‐impregnated Chromarod S‐II by development with benzene/chloroform/acetic acid (70∶30∶2, v/v/v) (mobile phase A) or hexane/ ether/acetic acid (70∶30∶1, v/v/v) (mobile phase B). Mobile phase B had an advantage over mobile phase A in terms of free space to add internal standards for simultaneous quantitation and was employed.p‐Hydroxybenzoic acid andp‐carboethoxy benzyl alcohol, which appeared between 1,2‐diolein and 1‐moloolein, were adopted as the internal standards. The calibration curves relating internal standards to each glyceride were all approximated by the equations Y=aXb giving high correlations. The method was applied to hydrolysis of triolein by pancreatic lipase.
The effect of dietary partially hydrogenated marine oils on desaturation of fatty acids in rat liver microsomes
Authors: Svensson Lennart 
Published: December 2006

AbstractThe influence of dietary partially hydrogenated marine oils on distribution of phospholipid fatty acids in rat liver microsomes was studied with particular reference to the metabolism of linoleic acid. Five groups of weanling rats were fed diets containing 20% (w/w) peanut oil (PO), partially hydrogenated peanut oil (HPO), partially hydrogenated Norwegian capelin oil (HCO), partially hydrogenated herring oil (HHO), and rapeseed oil (RSO) for 10 weeks. The partially hydrogenated oils were supplemented with linoleic acid corresponding to 4.6 cal % in the diets. Accumulation of linoleic acid and reduced amount of total linoleic acid metabolites were observed in liver microsomal phospholipids from rats fed partially hydrogenated oils as compared to PO feeding. The most striking effects on the distribution of ω6‐polyunsaturated fatty acids was obtained after feeding HHO, a marine oil with a moderate content oftrans fatty acids in comparison with HPO but rich in isomers of eicosenoic and docosenoic acids. Liver microsomal Δ6‐as well as Δ6‐desaturase activities as measured in vitro were reduced in rats kept on HHO as compared to PO dietary treatment. The results obtained suggest that the dietary influence of partially hydrogenated marine oils on the metabolism of linoleic acid might be better related to the intake of isomeric eicosenoic and docosenoic acids than to the total intake oftrans fatty acids.
Cholinephosphotransferase activity in human platelets
Authors: Gianfrancesco Goracci , Paolo Gresele , Arienti Giuseppe , Porrovecchio Patrizia , Nenci Giuseppe G. , Porcellati Giuseppe 
Published: December 2006

AbstractDisrupted human platelets possess a cholinephosphotransferase activity (EC 2.7.8.2) whose properties have been studied in this work. The labeling of choline glycerophospholipid (CGP) from radioactive cytidine‐5′‐diphosphate choline (CDP‐choline) in vitro shows a maximum at pH 8.0 (using Hepes [4‐(2‐hydroxyethyl)‐piperazine‐1‐ethane‐2‐sulfonic acid] as a buffer) and is stimulated by Mn2+, Mg2+ and diacylglycerol. The enzymic activity is inhibited by Ca2+. The dependence of human platelet choline‐phosphotransferase upon CDP‐choline concentration does not follow the Michaelis‐Menten equation. CMP strongly inhibits the reaction. The functional implications of this newly discovered platelet activity are briefly considered.
Biliary and fecal steroid excretion in rats fed partially hydrogenated soybean oil
Authors: Sugano Michihiro , Ide Takashi , Kohno Mitsuko , Watanabe Midori , Cho Young‐J. , Nagata Yasuo 
Published: December 2006

AbstractMale Wistar rats were fed cholesterol‐free or cholesterol‐enriched diets containing partially hydrogenated soybean oil with different levels oftrans‐fatty acids or unhydrogenated soybean oil at the 10% level. The linoleic acid content of hydrogenated fat diets was adjusted to 3.6% of the total energy. Hydrogenated fat diets contained 29% and 41%trans‐acids, mainly ast‐18∶1.Trans‐fats exerted no untoward effects on growth parameters, but increased liver weight. Dietary hydrogenated fats influenced neither the concentration nor composition of biliary steroids, irrespective of the presence or absence of cholesterol in the diet. In rats fed a cholesterol‐free diet, daily fecal output of neutral and acidic steroids was enhanced by hydrogenated fats and the magnitude of augmentation was proportional to the dietary level oftrans‐fatty acids. The increased fecal steroid excretion corresponded to an increase in total excreta. Hydrogenated fats also tended to enhance bile acid excretion when feeding a cholesterol‐enriched diet. The results suggest that dietarytrans‐fatty acids, in relation tocis‐polyunsaturated fatty acids, provoke demonstrable change in steroid homeodynamics.
Cooccurrence of C‐24 alkylated Δ7‐ and Δ5‐Sterols in the leaves ofBeta vulgarisin the leaves ofBeta vulgaris
Authors: Adler John H. , Salt Thomas A. 
Published: December 2006

AbstractThe 4‐desmethylsterols from the leaves ofBeta vulgaris are a mixture of Δ7‐sterols (71%) and Δ5‐sterols (29%). The Δ7‐sterols isolated are spinasterol (24α‐ethylcholesta‐7,22‐dien‐3β‐ol; 45%), 22‐dihydrospinasterol (24α‐ethylcholest‐7‐en‐3β‐ol; 24%), and avenasterol (24‐ethylcholesta‐7,24(28)‐dien‐3β‐ol; 1.5%). The Δ5‐sterols isolated are sitosterol (24α‐ethylcholest‐5‐en‐3β‐ol; 15%), 24ζ‐ethylcholesta‐5,22‐dien‐3β‐ol (7.5%), and 24ζ‐methylcholest‐5‐en‐3β‐ol (7%).
Determination of lipase specificity
Authors: Jensen Robert G. , DeJong Felice A. , Clark Richard M. 
Published: December 2006

AbstractSpecificity of lipases is controlled by the molecular properties of the enzyme, structure of the substrate and factors affecting binding of the enzyme to the substrate. Types of specificity are as follows. I. Substrate: (a) different rates of lipolysis of TG, DG, and MG by the same enzyme; (b) separate enzymes from the same source for TG, DG and MG. II. Positional: (a) primary esters; (b) secondary esters; and (c) all three esters or nonspecific hydrolysis. III. Fatty acid, preference for similar fatty acids. IV. Stereospecificity: faster hydrolysis of one primarysn ester as compared to the other. V. Combinations of I–IV. Lipases with these specificities are: Ia, pancreatic; Ib, postheparin plasma. IIa, pancreatic; IIb,Geotrichum candidum, for fatty acids withcis‐9‐unsaturation, and IIc,Candida cylindracea. III,G. candidum for unsaturates. IV.sn‐1, postheparin plasma andsn‐3 human and rat lingual lipases. V. Rat lingual lipase. Methods for determination involve digestion of natural fats of known structure and synthetic acylglycerols followed by analysis of the lipolysis products. All of the types of specificity have been detected with use of synthetic acylglycerols. Detection of stereospecificity requires enantiomeric acylglycerols which are difficult to synthesize, so other methods have been developed. These involve the generation of 1,2‐(2,3) DG and resolution of the enantiomers. Trioleoylglycerol or racemic TG can be used as substrates. If the lipase is stereospecific, then either thesn‐1,2‐ or 2,3‐enantiomer will predominate. The relative amounts of the enantiomers can be determined by measurement of specific rotation, and nuclear magnetic resonance spectra. The DG can also be separated by conversion to phospholipids and hydrolysis with phospholipases A‐2 or C. Applications of these procedures are discussed and data on the specificity of various lipases presented.
Enhanced incorporation of exogenous arachidonic acid into phosphatidylinositol and other phospholipids during the early stages of thrombin‐induced aggregation in gerbil platelets
Authors: Agwu D. E. , Johnstone I. , Crane S. , Holub B. J. 
Published: December 2006

AbstractThe degradation of platelet phospholipids via phospholipase activity is known to occur during thrombin‐induced platelet aggregation. Both phosphatidylinositol and phosphatidylcholine are considered to be sources of the released arachidonic acid which becomes a substrate for prostaglandin and thromboxane A2 formation. In this work, the effect of thrombin on the incorporation of exogenous arachidonic acid into platelet membrane phospholipids was studied. Suspensions of gerbil platelets were incubated in aggregometer cuvettes with [14C] arachidonic acid in the absence or presence of thrombin, and product formation was monitored by thin layer chromatography and scintillation counting. Within 30 sec, the entry of arachidonic acid into phosphatidylinositol was increased by 165% in thrombin‐stimulated platelets over controls. Under identical conditions, the incorporation into phosphatidylcholine was increased by only 57%. These results suggest that the incorporation of exogenous arachidonic acid via lysophosphatidylinositol and lysophosphatidylcholine acyltransferase activities may be intimately associated with thrombin‐induced platelet aggregation in the gerbil.
A complete separation of lipids by three‐directional thin layer chromatography
Authors: Kramer J. K. G. , Fouchard R. C. , Farnworth E. R. 
Published: December 2006

AbstractA novel three‐directional thin layer chromatography (TLC) method is reported by which all the polar and neutral lipids are isolated on a single TLC plate. Following resolution of the phospholipids by two‐directional TLC, lipids are visualized by ultraviolet light after spraying with 2′,7′‐dichloro‐fluorescein. A line is drawn across the plate, parallel to the second direction of development, separating the resolved phospholipids and the neutral lipids concentrated along the solvent front. The TLC plate is then chromatographed in the reverse direction of the second development to resolve the neutral lipids. By exposing the lipids to HCl fumes after the first development, the plasmalogen content of the lipids may also be determined. This new technique is rapid and lends itself to qualitative and quantitative analyses of total lipids.