bluuebunny/crossref_metadata_2025 huggingface dataset:
Species difference of liver cytosolic fatty acid‐binding protein in rat, mouse and guinea pig
Authors: Kawashima Yoichi , Tachibana Yuka , Nakagawa Sayuri , Kozuka Hiroshi
Published: November 2006

Binding properties of liver cytosolic protein for oleic acid, palmitoyl‐CoA and bromosulphophthalein (BSP) were compared for rat, mouse and guinea pig. Hepatic cytosol of rat, mouse and guinea pig contained proteins with a molecular weight of ca. 12,000 and had an affinity for [1‐14C]‐oleic acid. The concentration of fatty acid‐binding protein (FABP) was almost the same in livers of the animals of the 3 species and was ca. 50 μg/mg cytosolic protein. Electrophoretic studies revealed that FABP from hepatic cytosol of rat, mouse and guinea pig, purified with affinity chromatography, are distinct from one another in terms of their charge. FABP of rat liver was capable of binding any 3 ligands‐oleic acid, palmitoyl‐CoA and BSP—at relatively high binding capacity. FABP of mouse liver also bound oleic acid and palmitoyl‐CoA to a great extent, but its binding capacity for BSP was only one‐third that of rat liver. FABP of guinea pig liver bound less oleic acid and palmitoyl‐CoA than rat liver, whereas it had almost the same binding capacity for BSP as rat liver.
Analysis of the stearoyl‐CoA desaturase system in the Morris hepatoma 7288C and 7288CTC
Authors: Zoeller Raphael A. , Wood Randall
Published: November 2006

The microsomal stearoyl‐CoA desaturase system was examined in both the Morris hepatoma 7288CTC, maintained in the host Buffalo strain rat, and the Morris hepatoma 7288C, maintained in tissue culture. In vitro examination shows the stearoyl‐CoA desaturase system to be similar in the 2 tissues. Both show extremely low overall stearoyl‐CoA desaturase activity, having 4% and 8% of normal liver values respectively. Examination of the electron transport system showed both tissues have decreased electron transport components cytochrome b5 and cytochrome b5 reductase. Particularly noticeable were the extremely low levels of cytochrome b5 (2% compared with normal liver). Microsomes from both tissues showed a decreased ability to reduce an artificial electron acceptor, cytochrome c. With the low levels of cytochrome b5 observed in these tissues, the low levels of overall desaturase activity may be caused by lack of terminal enzyme, lack of sufficient cytochrome b5, or both. Analysis of the stearoyl‐CoA desaturase system in cultured hepatoma cells suggests that these cells are similar to the host‐grown tumor in this respect and may be used as a model in further examinations of the stearoyl‐CoA desaturase system.
Effects of bile acid oxazolines on gallstone formation in prairie dogs
Authors: Cohen Bertram I. , Singhal Anil K. , Stenger Richard J. , May‐Donath Patricia , Finver‐Sadowsky Judith , McSherry Charles K. , Mosbach Erwin H.
Published: November 2006

The effects of 2 bile acid analogs, chenodeoxy‐oxazoline [2‐(3α,7α‐dihydroxy‐24‐nor‐5β‐cholanyl)‐4,4‐dimethyl‐2‐oxazoline] and ursodeoxy‐oxazoline [2‐(3α, 7β‐dihydroxy‐24‐nor‐5β‐cholanyl)‐4,4‐dimethyl‐2‐oxazoline] were examined in the prairie dog model of cholesterol cholelithiasis. Gallstones and biliary cholesterol crystals were induced in 5 out of 6 male prairie dogs fed a semisynthetic diet containing 0.4% cholesterol for 8 weeks. Six animals maintained on a low cholesterol control diet (0.08% cholesterol) exhibited neither gallstones nor biliary cholesterol crystals. The addition of 0.06% chenodeoxy‐oxazoline to the lithogenic diet did not prevent induced cholelithiasis or the appearance of cholesterol crystals in bile. In contrast, 0.06% dietary ursodeoxy‐oxazoline prevented gallstones in 5 out of 6 prairie dogs (but cholesterol crystals were present in the bile of 4 of these animals). Histologically, most of the livers from the prairie dogs fed the cholesterol‐supplemented semisynthetic diet showed bile duct proliferation, inflammatory infiltration and fibrosis along the portal tracts. These pathologic changes were generally not ameliorated by adding chenodeoxy‐oxazoline or chenodeoxy‐oxazoline plus chenodeoxycholic acid to the diet. Portal tract pathology was markedly reduced in most animals by adding ursodeoxy‐oxazoline to the cholesterol‐supplemented diet. The pathologic changes overall could best be correlated with the presence of gallstones, but not with the incidence of biliary cholesterol crystals.
Effects of cyclopropene fatty acids on the lipid composition of the Morris hepatoma 7288C
Authors: Zoeller Raphael A. , Wood Randall
Published: November 2006

Fatty acids ofSterculia foetida were added to the medium used to maintain the Morris hepatoma 7288C in culture. The effect of this supplement on the lipid composition was examined. Overall, monoene levels were decreased with 18∶1 levels reduced by 40%. Saturated fatty acid levels were increased, with stearate (18∶0) levels 220% of control values. No effect occurred on the level of polyunsaturates (18∶2, 20∶4, 22∶5, 22∶6). These changes in fatty acid makeup were observed in both neutral and phospholipid fractions, and all lipid classes were affected. Triglycerides were most affected with a 66% decrease in 18∶1. There appeared to be little specificity of effect in the phospholipids with 18∶1 levels decreased 40–60% in all classes. All classes were therefore dependent on an endogenous supply of 18∶1. Examination of the distribution of geometrical isomers of 18∶1 reveals that in all lipid classes, except diphosphatidylglycerol (DPG), the ratio of Δ11 to Δ9 isomer decreased toward the isomeric distribution displayed by total medium lipids. In DPG, although 18∶1 levels were lowered, the isomeric distribution increased. DPG, synthesized and found in the mitochondria, may use a separate pool of 18∶1 during synthesis. Cyclopropene fatty acids (sterculic and malvalic) were incorporated into both neutral and phospholipid fractions with preferential incorporation into triglycerides. Cyclopropene fatty acids were not selectively incorporated into any phospholipid species. Sphingomyelin did not incorporate cyclopropene fatty acids, indicating that a different class of acyltransferase is used in the formation of this phospholipid class.
Side‐chain structural requirements for sterol‐induced regulation ofPhytophthora cactorum physiology
Authors: Nes W. David , Stafford Allan E.
Published: November 2006

The influence of cholesterol. (E)‐17(20)‐dehydrocholesterol, sitosterol, (Z)‐17(20)‐dehydrocholesterol and 20‐isocholesterol on growth and sexual morphogenesis inPhytophthora cactorum has been examined. Optimal growth‐response and production of oospores occurred with the 3 former sterols, which posseesed “right‐handed” side chains (C22trans‐oriented to C13). Abnormal hyphae and aborted oospores were evident in mycelia cultured with sterols having side chains with “left‐handed” structures, i.e., 20‐isocholesterol and (Z)‐17(20)‐dehydrocholesterol. The induction of the sexual cycle lacked a selectivity for stereochemistry in the side chain. The results are interpreted to imply that fungal recognition of the sterol molecule in the reproductive phase of the life cycle is of 2 types: one involves discrimination of stereochemical features of the sterol side chain (oospore production); in the other, no functional significance can be attributed to conformation or configuration of side chain moieties (sexual structure induction). Growth response to dietary sterol seeems to fall into the former category.
Determination of the composition of mixed micelles of bile salts by kinetic dialysis
Authors: Lake M. , Organisciak D. T.
Published: November 2006

A kinetic dialysis method for determining the critical micelle concentration and the composition of mixed micelles has been adapted to study a binary system of bile acids. Using kinetic dialysis, the critical micelle concentrations of taurocholate, deoxycholate and taurodeoxycholate were determined. Monomer analysis was performed by colorimetric and radioactive tracer techniques on aliquots of the dialysates. Similarly, the composition of mixed micelles made from various molar fractions of deoxycholate and taurocholate containing tritium and14C tracers were determined by this method. The results suggest that, for these bile acids, mixed micelle composition is largely predicted by the molar composition of the binary system. Kinetic dialysis has proven to be a rapid procedure and to yield results that agree with critical micelle concentration values previously reported.
Behavior of sugar derivatives in procedure for ganglioside isolation
Authors: Yates Allan J. , Warner Jean K.
Published: November 2006

A common method of studying ganglioside metabolism is to measure the amounts of radioactivity incorporated into ganglioside from a radiolabeled precursor. This requires that radioactive nonganglioside material be completely removed from the ganglioside fraction. Nucleotide sugars and aminosugars comprise an important source of such contaminants. Therefore, we have studied their behaviors in several procedures currently employed to isolate gangliosides. Over 50% of the radioactivity associated with several nucleotide sugars added to a brain homogenate is extracted with chloroform/methanol (2∶1, v/v), and most of this is recovered in the upper phase of a Folch partition. Dialysis against water removes almost all of the free aminosugar but only 70% of nucleotide sugar. Treatment with alkaline phosphatase, phosphodiesterase and alkaline methanol followed by dialysis removes almost all of the nucleotide diphosphate sugars but only 88% of cytidine 5′‐monophosphate sialic acid (CMP‐NeuAc). Nucleotide sugars cannot be separated from gangliosides by Unisil or latrobead chromatography, but nucleotide diphosphate sugars and gangliosides are resolved with Sephadex LH‐20 chromatography following treatment with phosphodiesterase and alkaline phosphatase. CMP‐NeuAc was not satisfactorily separated from gangliosides using any of the procedures.
Increased lysolecithin acyltransferase activity in the plasma of type II hyperlipoproteinenic patients
Authors: Subbaiah Papasani V. , Ogilvie James T.
Published: November 2006

Lecithin‐cholesterol acyltransferase (LCAT) in human plasma has been shown to acylate lysolecethin to lecithin in presence of low density lipoprotein (LDL). To determine the physological importance of LDL in activating lysolecithin acyltransferase (LAT) activity, we assayed the LAT activity in 18 hypercholesterolemic (Type II) patients and 15 control subjects. The enzyme activity was about 60% higher in the patients compared with the controls. On the other hand, the LCAT activity, measured by 2 different procedures, as well as enzyme mass, determined by radioimmuno assay, were comparable in the controls and hypercholesterolemics. The LAT activity was highly correlated with LDL levels in the plasma, but the LCAT activity and the enzyme mass had no correlation with the LDL levels. These results show that the plasma LDL is the rate‐limiting activator of the enzyme, and pathological conditions, resulting in higher LDL levels, also cause higher LAT activities.
Cholesterol binding capacity of fiber from tropical fruits and vegetables
Authors: Lund Eric D.
Published: November 2006

The cholesterol binding capacity of 28 fiber samples from a variety of the more common tropical fruits and vegetables was determined. The binding capacity of cholestyramine, cellulose, lignin, guar gum and citrus pectin were also determined. Capacities were evaluated by an in vitro method that simulates the effect of the human digestive system on fiber using a series of enzymatic treatments before the binding was determined. Binding values varied from 3% for a soluble fraction of cassava to 84% for cholestyramine. Values for most fruit and vegetable fiber samples were less than or ca. equal to cellulose or lignin (20% and 16%, respectively). Apart from cholestyramine, sweet potato was the most effective binder (30%). Citrus pectin, at 8%, was a relatively poor binder. The capacity of guar gum (17%) was slightly less than cellulose. These data do not support the conclusion from in vivo studies that the hypocholesteremic effects observed for citrus pectin and guar gum are the result of the direct binding of cholesterol or bile acids in the large intestine.
Pathways of acetyl CoA production for lipogenesis from acetoacetate, β‐hydroxybutyrate, pyruvate and glucose in neonatal rat lung
Authors: Sheehan Patricia M. , Yeh Yu‐Yan
Published: November 2006

The rate of fatty acid synthesis from acetoacetate (AcAc) is 2–3 times greater than from glucose in developing rat lung. To determine the reason for this difference, we investigated the pathways of lipogenesis from [3‐14C] AcAc, [3‐14C]β‐hydroxybutyrate (βOHB), [U‐14C] glucose or [2‐14C] pyruvate in minced lung tissue of 3‐ to 4‐day‐old rats. The addition of (−)hydroxycitrate, an inhibitor of ATP‐citrate lyase, inhibited fatty acid synthesis from glucose, pyruvate, and βOHB by 88%, 70% and 60%, respectively, but had no effect on that from AcAc. Benzene 1,2,3‐tricarboxylate, an inhibitor of tricarboxylate translocase, inhibited fatty acid synthesis from all substrates by at least 50%. Incubation with aminooxyacetate, an inhibitor of aspartate aminotransferase, has no effect on lipid synthesis from glucose, pyruvate or AcAc, but increased lipid synthesis from βOHB. Results indicate that for lipid synthesis in the neonatal lung, acetyl CoA from AcAc is derived predominantly from a cytoplasmic pathway involving AcAcCoA synthetase and AcAcCoA thiolase, whereas citrate is the major route of acetyl group transfer from glucose. Lipogenesis from βOHB involves both the cytoplasmic and citrate pathways.
Effects of different levels of dietarytrans‐octadecenoate on steroid metabolism in rats
Authors: Watanabe Midori , Cho Young‐J. , Ide Takashi , Sugano Michihiro
Published: November 2006

Rats were fed semipurified diets containing olive oil or partially hydrogenated corn oil at the 5 or 20% level for ca. 30 days. These fat diets contained the same amount of octadecenoate but differed in the geometry with respect to each fat level. Contents oft‐18∶1 were 26% and 41% of total fatty acids, respectively. The linoleic acid content was also made equivalent (3.8 energy %). After feeding on cholesterol‐free diets, rats ontrans fat, compared to those oncis fat, showed: (a) no changes in serum cholesterol and apolipoprotein levels, (b) no effects on the bile flow and concentrations of biliary cholesterol or bile acids, (c) a trend toward increased fecal excretion of neutral and acidic steroids, (d) a lesser extent of transformation of cholesterol to coprostanol in the gut, and (e) no changes in the composition of biliary and fecal bile acids. Observations (c) and (d) were more marked with a hightrans fat regimen. These observations, except for serum apolipoproteins and fecal steroid excretion, were practically reproducible even when rats were fed cholesterol‐enriched diets.
Subcellular localization of triacylglycerol synthesis in spinach leaves
Authors: Martin B. A. , Wilson R. F.
Published: November 2006

The subcellular location of diacylglycerol acyltransferase (EC 2.3.1.20) in spinach leaves (Spinacia oleracea L. cv. Longstanding Bloomsdale) was determined after sucrose‐gradient centrifugation of tissue homogenates. Enzyme activity was associated primarily with gradient fractions containing oil bodies and intact chloroplasts. Gradient fractions enriched with the endoplasmic reticulum contained insignificant levels of diacylglycerol acyltransferase activity. On the basis of chlorophyll, diacylglycerol acyltransferase activity in crude homogenates was not significantly different from that in intact chloroplasts after Percoll density‐gradient centrifugation. Among membrane fractions isolated from hypotonically treated chloroplasts, envelopes contained the greatest diacylglycerol acyltransferase and galactosyltransferase activity. These data demonstrated that chloroplasts were a subcellular site for triacylglycerol biosynthesis in spinach leaves.
Effect of antioxidants on lipid peroxidation in iron‐loaded rats
Authors: Dillard Cora J. , Downey Jeanne E. , Tappel Al. L.
Published: November 2006

Indirect evidence has suggested that lipid peroxidation is associated with iron overload in vivo. As a measure of lipid peroxidation, pentane expired in the breath of rats loaded with an accumulated dose of either 100 mg or 186–200 mg of iron injected intraperitoneally as iron dextran was measured over a 7 to 8 week period, and the effect on pentane production of feeding antioxidant‐supplemented diets was determined. By the seventh week of feeding the diets, rats fed 0.3% L‐ascorbic acid produced 17% less (P=0.03) pentane than did rats fed the basal antioxidant‐deficient diet, whereas rats fed 0.004% dl‐α‐tocopherol acetate produced 92% less (P<0.001). After being fed the basal diet for 7 weeks, iron‐loaded rats produced 76±9 pmol pentane/100 g body wt/min. When synthetic antioxidants were added to the diet at a concentration of 0.25%, the order of effectiveness in decreasing pentane production after 1 week was: N,N′‐diphenyl‐p‐phenylenediamine > ethoxyquin > butylated hydroxyanisole > butylated hydroxytoluene > propyl gallate ∼ no antioxidant. After removal of either ethoxyquin or N,N′‐diphenyl‐p‐phenylenediamine from the diets for 1 week, pentane production increased to a high level. The total amount of lipid soluble fluorophores in individual spleens of rats fed N,N′‐diphenyl‐p‐phenylenediamine, ethoxyquin, dl‐α‐tocopherol acetate, ascorbic acid and no antioxidant were correlated significantly with the corresponding total integrated amount of pentane produced by the individual rats over the 7 to 8 week period. This study has provided some of the most direct evidence to date that lipid peroxidation is associated with iron overload in vivo.
Analysis of triglyceride species by high‐performance liquid chromatography via a flame lonization detector
Authors: Phillips F. C. , Erdahl W. L. , Nadenicek J. D. , Nutter L. J. , Schmit J. A. , Privett O. S.
Published: November 2006

The analysis of triglyceride species by high performance liquid chromatography (HPLC) with a flame ionization detector (FID) and reversed‐phase chromatography using chemically bonded octadecyl silane (ODS) Zorbax columns and gradient or isocratic solvent elution with methylene chloride/acetonitrile is described. Triglycerides containing acyl groups of critical pairs,trans and positional isomers, as well as mixtures of even and odd chain lengths are separated. Identification of triglycerides is made on the basis of retention times compared with equivalent and theoretical carbon numbers, and comparison with chromatograms of reference triglyceride mixtures. The methodology is demonstrated by fractionizing the triglycerides of olive oil under different chromatographic conditions using single and coupled conventional 250×4.6 mm columns and a short 80×6.2 mm column for fast separations.
Polyunsaturated fatty acids and neutral lipids in developing larvae of the oyster,Crassostrea virginica
Authors: Chu Fu‐Lin E. , Webb Kenneth L.
Published: November 2006

The fatty acid composition of oyster larvae at various stages, as well as of the algal diet, were determined by gas liquid chromatography (GC). Saturated fatty acids are the major fatty acid components in all larval stages and account for 34–62%, 30–35% and 35–81% of the neutral, polar and total lipids of algal‐fed larvae respectively. Weight percentage of saturated fatty acid in “starved” larvae was consistently higher (63–81%) during the whole period. The total polyunsaturated fatty acids were higher in the polar lipids than in the neutral lipids. The concentration of the ω3 fatty acids also was comparatively higher in the polar lipids than in the neutral lipids. In the total and neutral lipid fractions, the weight percentage of polyunsaturated and ω3 fatty acids was higher in the eyed than in the pre‐eyed (pediveliger) larvae. Eicosapentaenoic acid (20∶5ω3) and 22∶6ω3 were not detected in lipids of “starved” and young larvae. There was an accumulation of 20∶5ω3, 22∶6ω3, and total ω3 fatty acids in the older larvae. Lipid classes were separated by thin layer chromatography (TLC). There was no qualitative change in lipid composition during larval development, but a marked increased of triacylglycerol in larvae up to the stage of maturation in algae‐fed larvae.
Inhibition of fatty acid synthesis in isolated adipocytes by 5‐(tetradecyloxy)‐2‐furoic acid
Authors: Halvorson David L. , McCune Sylvia A.
Published: November 2006

The compound 5‐(tetradecyloxy)‐2‐furoic acid (TOFA), a hypolipidemic agent, inhibits fatty acid synthesis, lactate and pyruvate accumulation and CO2 release in isolated at adipocytes. TOFA stimulates the accumulation of citrate. ATP levels are not lowered by TOFA. In comparison with the natural fatty acid, oleate, TOFA exhibited a much greater inhibitory effect on lipogenesis. TOFyl‐CoA formation within intact adipocytes was demonstrated. Although not inhibited by TOFA, acetyl‐CoA carboxylase is inhibited by TOFyl‐CoA. It is proposed that many of the metabolic effects of TOFA in isolated adipocytes can be explained by TOFyl‐CoA inhibition of acetyl‐CoA carboxylase. TOFA inhibits glycolysis as a secondary event with the primary event of inhibition of fatty acid synthesis causing an accumulation of citrate which is an inhibitor of phosphofructokinase.
Quantitative analysis of triglyceride species of vegetable oils by high performance liquid chromatography via a flame lonization detector
Authors: Phillips F. C. , Erdahl W. L. , Schmit J. A. , Privett O. S.
Published: November 2006

A method for the quantitative analysis of triglyceride species composition of vegetable oils by reversed‐phase high performance liquid chromatography (RP‐HPLC) via a flame ionization detector (FID) is described. Triglycerides are separated into molecular species via Zorbax chemically bonded octadecylsilane (ODS) columns using gradient elution with methylene chloride in acetonitrile. Identification of species is made by matching the retention times of the peaks in the chromatogram with the order of elution of all of the species that could be present in the sample on the basis of a random distribution of the fatty acids and comparision of experimental and calculated theoretical carbon numbers (TCN). Quantitative analysis is based on a direct proportionality of peak areas. Differences in the response of individual species were small and did not dictate the use of response factors. The method is applied to cocoa butter before and after randomization, soybean oil and pure olive oil.
Heterogeneous labeling of adipocytes during in vivo‐in vitro incubation of epididymal fat pads of aging mice with [1‐14C] palmitate
Authors: Hill V. , Baker N.
Published: November 2006

We have hypothesized that the in vivo‐in vitro technique of Stein and Stein for studying free fatty acid incorporation into adipose tissue triglycerides and phospholipids may introduce artifacts due to diffusion barriers such as collagenous membranes, especially in fat pads of old animals. By using this technique in young and old mice and peeling the external cells, either physically or by collagenase treatment, we were able to show that the outer adipocytes are preferentially labeled. However, this pattern of heterogenous labeling occurred in fat pads of both young (10–14 weeks) and old (80 weeks) mice. Fat pads are known to develop thicker, collagenous outer membranes during aging. Therefore, it seems likely to us that the marked decrease in free fatty acid esterification in fat pads of old mice, using the in vivo‐in vitro method that we have described previously and confirmed here, could have been due to greater diffusion barriers in the tissues of the older mice.
Hypolipidemic effects of clofibrate and selected chroman analogs in fasted rats: II. High sucrose‐fed animals
Authors: Mukhopadhyay A. , Patel S. T. , O'Brien M. , Kokrady S. S. , Newman H. A. I. , Witiak D. T. , Lanese R. R. , Rice J. C. , Feller D. R.
Published: November 2006

The hypolipidemic properties of ethyl 6‐chlorochroman‐2‐carboxylate (II), 6‐phenylchroman‐2‐carboxylate (III) and 6‐cyclohexylchroman‐2‐carboxylate (IV) were compared to clofibrate (I) in sucrose‐fed fasted male Sprague‐Dawley rats. All compounds were administered at doses of 0.2 and 0.4 mmol/kg, orally, twice daily for 7 consecutive days. In this model, II was a more effective hypocholesterolemic drug than clofibrate, whereas III and IV were inactive. Chlorochroman II, like clofibrate, decreased serum α‐lipoprotein cholesterol and pre‐β‐lipoprotein triglyceride concentrations and concomitantly increased serum β‐lipoprotein triglyceride concentrations. In clofibrate‐treated rats, serum free cholesterol concentrations increased concurrent with a reduction in serum lecithin: cholesterol acyltransferase activity, but no such correlation was observed for II. Only II lowered liver cholesterol levels and increased liver triglyceride levels. No consistent inhibition of liver microsomal 3‐hydroxy‐3‐methylglutaryl‐CoA reductase activity was observed with these analogs. The observed changes in triglyceride and cholesterol concentrations among serum lipoproteins were of a greater magnitude after chlorochroman II and clofibrate administration to sucrose‐fed rats than in our previous studies using chow‐fed fasted rats. These data suggest that chloro‐substitution at the 6‐position of the phenylchroman ring is important for hypolipidemic activity of these cyclic clofibrate analogs.
Reversed‐phase thin layer chromatography of some common sterols
Authors: Domnas Aristotle J. , Warner Steven A. , Johnson Susan L.
Published: November 2006

The chromatographic mobilities of 17 sterols and squalene on reversed‐phase thin layer plates with four nonaqueous solvent systems is described. A degree of separation adequate to identify several of the sterols was obtained. It was possible to separate the pairs: cholestanol, epicholestanol; coprostanol, epicoprostanol; 5β‐cholestan‐3α and 3β‐ol and lanosterol, dihydrolanosterol.
Fatty acid composition ofIxiolaena brevicompta F. Muell. Seed Oil
Authors: Ford Glenn L. , Whitfield Frank B. , Walker Keith H.
Published: November 2006

The seeds ofIxiolaena brevicompta F. Muell. (family Compositae) contained an oil (12%) in which the major fatty acids present are palmitic (7%), stearic (5%), oleic (8%), linoleic (51%) and crepenynic ical and physical methods. The bioactivity of crepenynic acid is discussed with respect to extensive mortalities of sheep grazing on mature seededI. brevicompta.
Pulmonary surfactant lipid synthesis from ketone bodies, lactate and glucose in newborn rats
Authors: Sheehan Patricia M. , Yeh Yu‐Yan
Published: November 2006

The contribution of acetoacetate (AcAc), β‐hydroxybutyrate (βOHB), lactate and glucose to pulmonary surfactant lipid synthesis in three‐to five‐day‐old rats was measured. Minced lung tissue was incubated with3H2O and [3‐14C]AcAc, [3‐14C]βOHB, [U‐14C]lactate or [U‐14C]glucose, and the radioactivity incorporated into surfactant lipids was measured. When expressed as nmol of substrate incorporated/g lung tissue per four hr, lactate was incorporated more rapidly than other substrates into total surfactant lipids and phosphatidylcholine (PC). There was no difference in the rates of incorporation of lactate, AcAc or glucose into disaturated PC (DSPC). Substrates other than glucose were incorporated almost exclusively into fatty acids, whereas 60–80% of glucose incorporated into surfactant phospholipids was found in fatty acids, with the remaining in glyceride‐glycerol. When expressed as nmol acetyl units incorporated/g lung tissue per four hr, the rates of AcAc, lactate and glucose incorporation into total surfactant fatty acids were comparable. Glucose incorporation into DSPC and PC was greater than that of AcAc and lactate. When glucose was the only exogenous substrate added to the incubation medium, it contributed 37% of total surfactant fatty acids synthesized de novo. In the presence of other substrates, the contribution of glucose to de novo fatty acid synthesis dropped to 14–20%. In the presence of unlabeled glucose,14C‐labeled AcAc, lactate and βOHB contributed 52%, 40% and 19%, respectively, of the total fatty acids synthesized de novo. The rate of βOHB incorporation into surfactant lipids was only about 50% that of other substrates and was accompanied by low activity of β‐hydroxybutyrate dehydrogenase measured for newborn lung. These results demonstrate that AcAc and lactate are important precursors for surfactant lipids in neonatal rat lung.
Suppression by dexamethasone of isoproterenol‐mediated changes in fatty acyl‐CoA desaturase activity of Tetrahymena microsomes
Authors: Umeki Shigenobu , Nozawa Yoshinori
Published: November 2006

Preincubation ofTetrahymena pyriformis cells with dexamethasone inhibited the microsomal fatty acyl‐CoA desaturase activities of isoproterenol‐induced modulation; that is, an increase in Δ9‐desaturase activity accompanied by a decrease in Δ12‐desaturase activity. Although isoproterenol caused an increase in Δ12‐terminal component activity with decreased Δ12‐terminal component activity, dexamethasone reduced these isoproterenol‐mediated activity changes. In cells treated with dexamethasone prior to isoproterenol administration, stimulation of cyclic AMP accumulation by isoproterenol was inhibited. These results suggest that dexamethasone may repress isoproterenol modulation of the activity of terminal components (cyanide‐sensitive factor) in the fatty acyl‐CoA desaturase system by reducing the cyclic AMP level.
Raman studies of structural rearrangements induced in human plasma lipoprotein carotenoids by malondialdehyde
Authors: Verma Surendra P. , Philippot Jean R. , Bonnet Bernard , Sainte‐Marie Josette , Moschetto Yves , Wallach Donald F. H.
Published: November 2006

Raman and resonance Raman spectra of plasma lipoproteins ± malondialdehyde were studied at concentrations which block the normal receptor‐mediated uptake by cells. The strong resonance Raman bands at about 1010, 1162 and 1530 cm−1, due to the presence of carotenoids in the lipoproteins, are envisaged as structural probes. High resolution resonance Raman spectra of the 1500–1600 cm−1 region reveal multiple features suggesting the coexistence of several structural populations of β‐carotene whose precise assignment is complex. When plasma lipoproteins are reacted with malondialdehyde, a complex change occurs in the resonance Raman banding of β‐carotene in the 1500–1600 cm−1 region. Malonaldehyde (MDA) also modifies the acoustical region (70–200 cm−1 of low density lipoprotein (LDL) lipids. We suggest that malondialdehyde association with plasma lipoproteins alters the lipid structure via apoprotein or apoprotein/lipid associations.
Influence of hypo‐ and hyperthyroidism on rat liver glycerophospholipid metabolism
Authors: Dang An Q. , Faas Fred H. , Carter William J.
Published: November 2006

The effects of hyper‐ and hypothyroidism on enzyme activities involved in phospholipid metabolism in the rat liver were studied. Hyperthyroidism significantly decreases activities of both microsomal acyl‐CoA:glycero‐3‐phosphate acyltransferase (GPAT) (34%, p<0.01) and microsomal acyl‐CoA:1‐acylglycero‐3‐phosphocholine acyltransferase (GPCAT) (28–33%, p<0.01). This may contribute to the decreased proportions of certain unsaturated fatty acids found in microsomal phosphoglycerides in hyperthyroidism. Mitochondrial GPAT, phospholipase A2 and cytosol lysophospholipase are unaffected by hyperthyroidism. In contrast, hypothyroidism stimulates mitochondrial GPAT (38%, p<0.01) and microsomal GPCAT (14–19%) activities but decreases both mitochondrial phospholipase A2 (36%, p<0.01) and cytosol lysophospholipase (56%, p<0.01) activities. The increased GPCAT activity may contribute to the increased proportions of certain unsaturated fatty acids found in microsomal phosphoglycerides in hypothyroidism. Triiodothyronine (T3) treatment of the hypothyroid rat (25 μg/100 g body weight/day for four days) corrected phospholipase A2 and lysophospholipase activities to the level of the control rat, but failed to correct the increased mitochondrial GPAT activity and not only corrected but lowered GPCAT activity to the level of the hyperthyroid rat.
Thiobarbituric acid reaction of aldehydes and oxidized lipids in glacial acetic acid
Authors: Kosugi Hiroko , Kikugawa Kiyomi
Published: November 2006

Thiobarbituric acid (TBA) reaction of several aldehydes and oxidized lipids in glacial acetic acid was performed. All the samples were freely soluble in the solvent used. Saturated aldehydes produced a stable yellow pigment with an absorption maximum at 455 nm, a red pigment derived from malonaldehyde at 532 nm, and an orange pigment due to dienals at 495 nm. The absorbance maximum was 7–9 per μmol for saturated aldehydes, 27.5 per μmol for malonaldehyde and about 2 per μmol for dienals. Autoxidation of unoxidized lipids increased progressively in glacial acetic acid. When the TBA test was performed under nitrogen, autoxidation of unoxidized lipids was inhibited completely. While saturated aldehydes produced no yellow pigment under nitrogen, oxidized lipids produced a considerable amount of stable yellow pigment. The value for absorbance at 455 nm as a function of autoxidation time paralleled those of peroxide values. The absorbance of most oxidized lipids at 455 nm was higher than at 532 nm. Yellow pigment formation in the TBA test under nitrogen could not be ascribed to free saturated aldehydes but rather to unspecified closely related substances. The stable yellow pigment was found to be an excellent indicator of lipid oxidation.
Separation of isomeric lysophospholipids by reverse phase HPLC
Authors: Creer Michael H. , Gross Richard W.
Published: November 2006

A reverse‐phase high performance liquid chromatography (HPLC) method was developed which resolved isomers of lysophosphatidylcholine (LPC) differing in the location of the aliphatic chain (sn‐1 orsn‐2 position) and the position (Δ6 or Δ9) or geometric configuration (cis ortrans) of the olefin group in monounsaturated species. LPC isomers containing an acyl substituent at thesn‐2 position eluted before their 1‐acyl‐sn‐glycero‐3‐phosphocholine (1‐acyl LPC) counterparts. The retention times of both thesn‐1 andsn‐2 isomers of monounsaturated species increased in the order Δ9‐cis < Δ9‐trans < Δ6‐cis. The integrated ultraviolet absorbance (203 nm) in binary mixtures of the Δ9‐cis and Δ6‐cis 2‐acyl lysophospholipid isomers correlated with the lipid phosphorus content of corresponding column eluates (r‐0.994). Thus, the present method will facilitate synthesis of isomerically pure diradylphospholipids by providing homogeneous lysophospholipid precursors and help simplify the quantitative analysis of unsaturated lysophospholipid species.
Highly saturated lipid composition of ctenophore cilia: Possible indication of low membrane permeability
Authors: Morris Robert J. , Bone Q.
Published: November 2006

The lipids of ciliary membranes in two species of ctenophore are found to be distinguished by phospholipids containing short chain saturated fatty acids and by saturated sterols. Such a composition is expected to result in a much lower permeability of cilia membranes to water and other ions than the general body membranes. We suggest that this is related to the large surface area of the cilia and is a requirement, on the part of the ctenophore, to control water and ionic fluxes across its surface membranes.
Lipid composition of liver mitochondria and microsomes in hyperthyroid rats
Authors: Ruggiero F. M. , Landriscina C. , Gnoni G. V. , Quagliariello E.
Published: November 2006

Triiodothyronine‐induced alteration of the lipid pattern in rat‐liver mitochondria and microsomes has been investigated. In mitochondria, a 25% total cholesterol decrease and a 14% phospholipid increase have been detected. In these hyperthyroid rat liver organelles, a strong decrease in the total cholesterol/phospholipid molar ratio occurs. On the contrary, in microsomes from the same animals, a decrease of about 23% has been measured for both total cholesterol and phospholipids; hence, in this fraction, the total cholesterol/phospholipid molar ratio is unaffected by hyperthyroidism. The liver mitochondrial phospholipid composition, unlike the microsomal composition, is altered significantly in hyperthyroid rats; a 7.4% phosphatidylcholine decrease is accompanied by a similar additive percentage increase of both phosphatidylethanolamine and cardiolipin. In regard to total phospholipid fatty acid composition in liver microsomes from hyperthyroid rats, no variation has been observed compared with the control rats, whereas in mitochondria from the same animals, a meaningful linoleic acid decrease with a similar arachidonic acid increase has been found. In addition to fatty acid alteration, the separated mitochondrial phospholipid classes also exhibit some increase in stearic acid. Among phospholipids, cardiolipin changes the most of the esterified fatty acids in hyperthyroid rat liver. In this compound, a strong increase in the percentage of both palmitic and stearic acid and a 32.4% decrease of linoleic acid have been found.
Total gangliosides, ganglioside species and the activity of neuraminidase in different brain regions and spinal cord of normal and undernourished rats
Authors: Bhargava P. , Rao P. S. , Vajreshwari A. , Shankar R.
Published: November 2006

Total gangliosides, their concentrations and the distribution of individual ganglioside species were determined in the spinal cord, pons‐medulla, midbrain, cerebellum, hypothalamus, cerebral cortex, olfactory lobes and the rest of the forebrain, of 18‐ and 33‐day‐old normal and food‐restricted and rehabilitated rats. The activity of neuraminidase in the different regions of the brain and spinal cord was determined. Differences in total gangliosides as well as individual species in different regions of the brain were observed. Among brain regions, while total ganglioside content was significantly reduced in the case of the cerebellum, the hypothalamus was the most affected in the distribution of ganglioside species and the activity of neuraminidase was decreased. The significance of the distribution of ganglioside species in different brain regions in relation to the activity of neuraminidase is discussed.
Diurnal variation of plasma methyl sterols and cholesterol in the rat: Relation to hepatic cholesterol synthesis
Authors: Strandberg T. E. , Tilvis R. S. , Miettinen T. A.
Published: November 2006

Free cholesterol of plasma low density lipoproteins (LDL) and high density lipoproteins (HDL) of the rat was high and that of plasma very low density lipoproteins (VLDL) was low during the dark period of the diurnal cycle. Variations in the esterified plasma sterols were inconsistent. Free methyl sterols were high in all lipoproteins during the dark phase. Simultaneously, the incorporation of14C‐acetate into nonsaponifiable sterols and the concentrations of free methyl sterols and cholesterol in the liver were elevated.
Effect of dietary fats on desaturase activities and the biosynthesis of fatty acids in rat‐liver microsomes
Authors: Mahfouz M. M. , Smith T. L. , Kummerow F. A.
Published: November 2006

Four groups of rats were fed diets containing 15% (w/w) high‐oleic safflower oil (SFO, rich incis‐18∶1 acids), a mixture of 80% partially hydrogenated soybean oil plus 20% corn oil (H+CO, rich intrans‐18∶1 acids), lard (L, rich in saturated fatty acids) and corn oil (Co, rich in 18∶2ω6). Fatty acid composition of liver microsomes and activities of the Δ5, Δ6 and Δ9 desaturases were determined. Microsomal Δ6 desaturase activity and arachidonic acid were lower in the H+CO group compared with SFO of L. No difference was found in the Δ5 or Δ6 desaturase activity of CO and SFO groups. Thus, the oleic‐acid level of the SFO diet had no effect on the metabolism of 18∶2ω6. Fluorescent polarization studies, usingtrans‐parinaric acid as a probe, showed no differences between the physical states of phospholipid vesicles made from lipids isolated from each group. We concluded that thetrans‐18∶1 acids in partially hydrogenated soybean oil have a more inhibitory effect than saturated acids on EFA metabolism, even in the presence of adequate amounts of essential fatty acid.
Response ofDrosophila tocis‐ andtrans‐22‐dehydrocholesterol II. Ability of sterols other than cholesterol to overcome the toxicity of thetrans isomer
Authors: Kircher Henry W. , Rosenstein Fumiko U. , Fogleman James C.
Published: November 2006

Four species ofDrosophila were tested, for two generations, for viability on media containing 13 different C27, C28 and C29 sterols with and withouttrans‐22‐dehydrocholesterol. Only cholesterol was effective for overcoming the toxic effect of therans derivative for all 4 species. The species varied in their ability to use the 13 sterols for growth, maturation and reproduction for 2 generations. The most tolerant species.D. pseudoobscura, could use 11 of the 13 sterols for structural and hormonal functions, whereas the most sensitive species,D. mettleri, could survive adequately on only 4 and less than adequately on another 3 of the 13 compounds. Desmosterol could not be used by any species, even for 1 generation.
Selective uptake and lack of dealkylation of phytosterols by cactophilic species ofDrosophila
Authors: Kircher Henry W. , Rosenstein Fumiko U. , Fogleman James C.
Published: November 2006

The selective absorption of cholesterol and campesterol and discrimination against sitosterol was demonstrated withDrosophila mojavensis andDrosophila nigrospiracula, using a synthetic medium and 2 natural host cacti. Preferential absorption of trace amounts of phytosterols from a large quantity of other lipids occurred whenD. arizonensis andD. mojavensis were reared from agria cactus. The absence of dealkylation of sitosterol to cholesterol was demonstrated withD. mojavensis andD. mettleri, reared on a sterol‐deficient medium supplemented with sitosterol.
Phospholipid requirement of alkylglycerol monooxygenase from rat liver microsomes
Authors: Ishibashi Teruo , Seyama Kuniaki
Published: November 2006

The alkylglycerol monooxygenase catalyzing the cleavage of the ether bond in alkylglycerol resides in rat liver microsomes. The enzyme preparation was freed of phospholipids by sodium deoxycholate treatment followed by gel filtration in the presence of deoxycholate. The removal of phospholipids markedly decreased the alkylglycerol monooxygenase activity. The activity of the delipidated enzyme, however, could be completely restored by the addition of phospholipid vesicles without detergent. When individual phospholipids were added, anionic phospholipids such as phosphatidylglycerol and diphosphatidyl‐glycerol were the most effective. These findings, along with our previous observation of a similar effect of liposomes on the purified enzyme, indicate that the amphipathic nature of the protein is responsible for the lipid dependence of enzymatic activity.
Effects of dietary triolein and sunflower oil on insulin release and lipid metabolism in zucker rats
Authors: Weekes T. E. C. , Wahle K. W. J. , Lebaijuri M. B.
Published: November 2006

Obese and lean male Zucker rats were fed ad libitum on diets containing either 50 (L) or 200 (H) g/kg diet of either triolein (T) or sunflowerseed oil (S). The specific activity of the hepatic microsomal Δ9 desaturase enzyme was depressed in both lean and obese rats fed the HS diet compared with the other three diets. The fatty acid composition of liver and subcutaneous white adipose tissue lipids were consistent with a lower Δ9 desaturation activity in rats fed the H diets, particularly for the HS diet. In both genotypes, microsomal Δ9 desaturase activity and the ratio of 16∶1/(16∶0+16∶1) fatty acids in liver lipids were inversely related to the proportion of 18∶2 in liver lipid. Plasma insulin concentrations and rates of glucose‐stimulated insulin release in vivo were higher in obese rats compared with lean rats, and plasma insulin levels were higher in rats fed S compared with T. There was no relationship between Δ9 desaturase activity and either plasma insulin concentration or rates of insulin release in vitro. These findings suggest that hepatic Δ9 desaturase activity of Zucker rats is responsive to changes in the proportion of 18∶2 in liver lipids but is not affected by changes in insulin secretion.
Effect of chlorphentermine on incorporation of [14C]choline in the rat lung phospholipids
Authors: Gonmori Kunio , Morita Tomoaki , Mehendale Harihara M.
Published: November 2006

The effect of chlorphentermine (CP) treatment (50 mg/kg/ day, per os [po]) on the incorporation of [14C]choline into rat lung phospholipid was studied.Total phospholipid content was increased 2.0‐fold and 1.7‐fold after seven and 14 days, respectively, compared with the pair‐fed rats. The incorporation of [14C]choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless, the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis.
Determination of the phospholipid composition of trout gill by latroscan TLC/FID: Effect of thermal acclimation
Authors: Hazel Jeffrey R.
Published: November 2006

The phospholipid composition of gill tissue from thermally acclimated rainbow trout,Salmo gairdneri, was determined by Iatroscan analysis following an initial development of the chromarods in a non‐polar solvent to remove neutral lipids. Standard curves for all phospholipids, although linear through most of the concentration range tested (1–40 μg), extrapolated to negative intercepts on the ordinate, indicating a decline in sensitivity at low phospholipid levels. In addition, the concentration dependence of the Iatroscan response varied by nearly 6‐fold among phospholipids. Of the major phospholipids, only lysophosphatidylcholine could not be quantitated accurately because of the presence of an interfering peak. Quantitation by Iatroscan yielded results which, in general, agreed well (within 5%) with results obtained by an independent phosphate analysis. Only in the case of phosphatidylinositol (PI) did the two analytical methods differ significantly; proportions of PI were 55% higher when determined by Iatroscan as opposed to phosphate analysis. Gill tissue from 5 C‐acclimated trout possessed higher proportions of phosphatidylethanolamine than tissue from 20 C‐acclimated trout. The Iatroscan provided a rapid and reliable means of quantitating the proportions of all the major phospholipids of trout gill, although there are some limitations to the general applicability of the technique.