bluuebunny/crossref_metadata_2025 huggingface dataset:
Accumulation of neutral lipids by human skin fibroblasts: Differential effects of saturated and unsaturated fatty acids
Authors: Rosenthal Miriam D.
Published: December 2006

The accumulation of neutral lipids by human skin fibroblasts grown in medium supplemented with fatty acids has been investigated. GM‐10 cells incorporated exogenous fatty acids into both phospholipids and neutral lipids. More [14C] oleate, linoleate, or linolenate was incorporated into triacylglycerol than was [14C] palmitate or stearate. Supplementation of medium containing delipidized serum with unsaturated fatty acids resulted in far more stimulation of [14C] glycerol incorporation into triacylglycerol than did supplementation with saturated fatty acids. Palmitate‐ and stearate‐fed cells incorporated sizable amounts of [14C] fatty acids and [14C] glycerol into diacylglycerol as well as triacylglycerol, especially at higher fatty acid concentrations. Increased oleate supplementation from 10–300 μM resulted in increased triacylglycerol synthesis and accumulation of discrete cytoplasmic lipid droplets; palmitate concentrations above 70 μm were toxic. Micrographs of the palmitate‐fed cells showed electron translucent slits, suggesting solid depositions of saturated fat, rather than the discrete osmiophilic droplets found in oleate‐fed cells. Although GM‐10 cells can synthesize fully saturated triacylglycerols, these data suggest that in cells fed saturated fatty acids, solid depositions of neutral lipids may sequester diacylglycerols and thus limit triacylglycerol synthesis.
Effect of fat and microflora on hepatic, small intestinal and colonic HMG CoA reductase, cytochrome P450 and cytochrome B5
Authors: Smith‐Barbaro Peggy , Hanson Debra , Reddy Bandaru S.
Published: December 2006

High levels of dietary fat caused a significant reduction in HMG CoA reductase activity in the liver of germ‐free rats whereas significantly elevated small intestinal enzyme activity was observed. Dietary fat had no significant effect on HMG CoA reductase activity in any tissue studied in the conventional rat. No significant change in colonic HMG CoA reductase activity was observed between any of the experimental groups. Rats fed a high‐fat diet tended to exhibit higher cytochrome P450 levels in all tissues studied, regardless of the presence of intestinal microflora.
Alteration of liver microsomal proteins from rainbow trout (Salmo gairdneri) fed cyclopropenoid fatty acids
Authors: Selivonchick Daniel P. , Williams Janet L. , Schaup Henry W.
Published: December 2006

Rainbow trout were fed diets containing cyclopropenoid fatty acids (CPFA) at 50 and 300 ppm with appropriate controls fed CPFA‐free diets. Treatment with CPFA altered the overall microsomal protein composition in a manner suggesting a reduction of high molecular weight components. One protein found in low concentration in controls appeared dominant in experimental animals, with the effect more pronounced as dietary levels of CPFA increased. The estimated molecular weight of this component was 41,500 daltons. Membrane fractions from CPFA‐fed fish separated on a Bio‐Gel P‐150 column revealed a significant number of small molecular weight components that suggest degradation of microsomal proteins. These data suggest an alteration by CPFA of membrane protein composition.
Influence of elaidate and erucate on heart mitochondria
Authors: Lee Hsu Chi Ming , Kummerow Fred A.
Published: December 2006

Male, weanling rats were fed, for up to six weeks, corn oil (CO), rapeseed oil (RSO), partially hydrogenated fat (HF), or a mixture of partially hydrogenated fat and corn oil (HF+CO). The respiratory activity of their isolated heart mitochondria, their hormone‐sensitive lipase activity, and the fatty acid compositions of the phospholipids of the mitochondria were determined. The results indicated that heart mitochondria isolated from rats which had been fed corn oil (CO) had a higher rate of oxygen uptake, showed higher respiratory control ratios, higher ADP/0 ratios and a higher rate of ATP synthesis than the heart mitochondria isolated from those fed rapeseed oil or hydrogenated fats. The oxygen uptake rates of the rat heart mitochondria isolated from each dietary group of rats was in order: oleyl carnitine ≫ erucyl carnitine > elaidyl carnitine. The decreased capacity to oxidize substrate by heart mitochondria which had been isolated from the hearts of rats fed rapeseed or hydrogenated soybean oil as compared with those fed corn oil as a sole source of dietary fat seemed related to the mitochondria lipid composition. The type of dietary fat fed had a pronounced influence on the mitochondrial fatty acid compositions of phosphatidylcholine, phosphatidylethanolamine, and cardiolipin. The lipase activity of the RSO‐fed group did not show any increment with either epinephrine or supplemental ATP treatment. The substrate preference for lipase activity in myocardium was corn oil‐triglycerides > trierucin > trielaidin > tripalmitin. However, cardiac lipid accumulation did not seem related to lipase activity in the myocardium.
Effect of dietary lipids on fatty acid composition of body lipid in rainbow trout (Salmo gairdneri)
Authors: Yu T. C. , Sinnhuber R. O. , Putnam G. B.
Published: December 2006

Three isocaloric diets were prepared. Diet 1 (Control) contained 22% herring oil. In diets 2 and 3, a third and a half of the herring oil was replaced, respectively, by an animal fat (lard) which contained a high percentage of saturated fatty acids. Each diet was fed to duplicate groups of rainbow trout for 14 wk. The results of the feeding trial indicated that the concentration of the saturated fatty acids in trout body lipid did not increase despite the high concentration of these fatty acids in Diets 2 and 3. Fish growth, feed efficiency, mortality and the level of fatty acid deposited in fish body lipid and phospholipids are discussed.
Age‐strain interrelations in lipid metabolism of rats
Authors: Story Jon A. , Gomolinski Eva , Czarnecki Susanne K. , Tepper Shirley A. , Kritchevsky David
Published: December 2006

Various aspects of lipid metabolism were compared in Fisher 344 (F) and Sprague‐Dawley (SD) rats aged 2, 6, 12, 18 and 24 months. The analyses included free and total cholesterol of serum and liver, LCAT, hepatic HMG‐CoA reductase, cholesterol 7α‐hydroxylase, fatty acid synthetase, acetyl CoA carboxylase and cholesterol synthesis from acetate or mevalonate. The body weight of SD rats increases with age whereas that of F rats plateaus at 9–12 months. Liver and aorta cholesterol levels were comparable for the 2 strains. Serum cholesterol varied but was usually lower in F rats. HMG‐CoA reductase and cholesterol 7α‐hydroxylase activities were not significantly different. Cholesterol synthesis from acetate was significantly higher only in 2‐month‐old F rats; synthesis from mevalonate was similar at each level. Acetyl CoA carboxylase and fatty acid synthetase activity were generally higher in F rats at every age level. The major difference between F and SD rats is in their pattern of weight gain with age. Differences in lipid metabolism are most marked between the young (2‐month) rats.
Diet and high density lipoproteins
Authors: Oster P. , Schlierf G. , Heuck C. C. , Hahn S. , Szymanski H. , Schellenberg B.
Published: December 2006

The acute and subacute effects of different diets on serum high density lipoprotein (HDL) cholesterol concentration and/or HDL composition are described. In obese normolipemic, hypercholesterolemic (type II) and hypertriglyceridemic (type IV) patients, low HDL cholesterol values remained low during total starvation for 2 weeks. Prudent diets in patients with type II and IV hyperlipoproteinemia had no significant effects on HDL cholesterol within 3 weeks, whereas in normal individuals, a high carbohydrate diet given for 10 days caused significant decreases in HDL cholesterol with concomitant increases in HDL triglycerides as compared to a high‐fat diet. The HDL triglyceride fatty acid composition changed in healthy volunteers during the day, depending on the type of ingested fat. The data demonstrate the possibility of acute manipulations of HDL in normal patients and the difficulties of normalizing low HDL cholesterol levels in patients by dietary means. Additional information on the function of HDL is desirable before the therapeutic manipulation of HDL cholesterol or other constituents of HDL can be evaluated regarding their effectiveness in the prevention of ischemic vascular disease.
Incorporation ofcis‐octadecenoic acids into the rat liver mitochondrial membrane phospholipids and adipose tissue triglycerides
Authors: Høy C. ‐E. , Hølmer G.
Published: December 2006

The incorporation of the dietarycis 18∶1 (n−12) andcis 18∶1 (n−10) into liver mitochondrial membrane phospholipids and adipose tissue trigly cerides was studied in 4 groups of rats fed diets containing 10 weight percent (wt%) of fat with the following contents of octadecenoic acids: 50%cis 18∶1(n−12) +9%cis 18∶1 (n−9); 25%cis 18∶1 (n−12)+32%cis 18∶1 (n−9); 50%cis 18∶1 (n−10)+10%cis 18∶1 (n−9); or 54%cis 18∶1 (n−9). Dietary linoleic acid was 3 wt% in all 4 groups. In the mitochondrial membranes, the isomeric octadecenoic acids were primarily incorporated into the 1‐position of phosphatidylcholines and phosphatidylethanolamines at the expense of saturated fatty acids. The maximal incorporations observed in the 1‐position of phosphatidylethanolamines were 4.8% 18∶1 (n−12) and 8.9% 18∶1 (n−10). No effects on the contents of polyunsaturated fatty acids in the phospholipids were seen. In the adipose tissue, the isomeric octadecenoic acids were incorporated at a level of 13%cis 18∶1 (n−12) or 23%cis 18∶1 (n−10), paralleled by a reduction in the content of oleic acid.
Effect of phagocytosis and lonophores on release and metabolism of arachidonic acid from human neutrophils
Authors: Walsh Christopher E. , Dechatelet Lawrence R. , Thomas Michael J. , O'Flaherty Joseph T. , Waite Moseley
Published: December 2006

Challenge of human neutrophils prelabeled with [3H]arachidonate and [14C] palmitate or [14C]‐stearate with opsonized zymosan or the Ca2+ ionophores A23187 or Ionomycin caused the release of [3H], but not [14C], fatty acid. With the ionophores, but not zymosan, considerable conversion of the [3H] arachidonate to hydroxyeicosatetraenoates occurred. Although various isomers were recovered, the 5‐hydroxyeicosatetraenoate appeared to be the major product. In these experiments, no [14C] products were detected such as lysophospholipid, diglyceride or monoglyceride. Although no definitive statement can be made about the mechanism of release of arachidonate, our data are most easily interpreted as the result of the action of a phospholipase A2.
The sterols and fatty acids from purified flagella ofChlamydomonas reinhardi
Authors: Gealt Michael A. , Adler John H. , Nes William R.
Published: December 2006

Purified flagella of the eukaryotic algaChlamydomonas reinhardi have a sterol composition (55% ergosterol [24β‐methylcholesta‐5,7,22‐trans‐trien‐3β‐ol] and 45% 7‐dehydroporiferasterol [24β‐ethylcholesta‐5,7,22‐trans‐trien‐3β‐ol]) identical of that of the whole algal cell. Fatty acids isolated fromC. reinhardi flagella were identified as 16∶0, 18∶0, 18∶1, 18∶2 and 18∶3. Whole cell fatty acids included 14∶0, 16∶2 and 16∶3 in addition to those found in the flagella. Triunsaturates comprised 22.9% of the flagellar fatty acids and 76.4% of those from the whole cell.
Subcellular distribution of the cytochrome P‐450 complex and glutathione peroxidase activity in vitamin E and essential fatty acid deficiency
Authors: Jensen Gunde Egeskov , Clausen Jørgen
Published: December 2006

Glutathione peroxidase (EC 1.11.1.9) (GSHPx) and P‐450 activity were measured in hepatic mitochondrial and microsomal fractions from rats deficient in vitamin E and/or essential fatty acids (EFA). The data were compared to corresponding normal values. GSHPx was significantly decreased in the mitochondrial matrix from animals in all 3 deficiency states. In vitamin E deficiency, a nonsignificant decreased GSHPx activity was found in mitochondrial membranes. Opposite to these findings, GSHPx was significantly increased in mitochondrial membranes of EFA‐deficient animals. In combined EFA and vitamin E deficiency, the mitochondrial membrane GSHPx activity was only insignificantly increased. The P‐450 complex activity was not detectable in the mitochondrial matrix. In mitochondrial membranes and microsomes, the P‐450 complex activity changed parallel to the GSHPx activity.
Differential metabolism of cholesterol and sitosterol byPhytophthora cactorum
Authors: Elliott C. G. , Knights B. A.
Published: December 2006

When cultures ofPhytophthora cactorum grown on sterol‐free medium were supplemented with a mixture of cholesterol and sitosterol, the sitosterol was initially taken up more rapidly than the cholesterol. Cholesterol was preferentially incorporated into the free sterol fraction and sitosterol into esters. More polar material was formed from sitosterol. Sitosterol is more active than cholesterol in promoting reproduction; this is attributed to the greater amount of polar metabolites formed from it.
Acylation of docosahexaenoic acid into phospholipids by intact human neutrophils
Authors: Tou Jen‐sie
Published: December 2006

Docosahexaenoic acid was not only acylated into phospholipids but also into triacylglycerols by intact human neutrophils. The distribution of radiolabeled docosahexaenoic acid among individual phospholipids was dependent on the incubation time. [1‐14C]Docosahexaenoic acid at all concentrations (1 to 8 μM) was acylated mainly into phosphatidic acid after 1–2 min incubation, and the radioactivity of phosphatidic acid started to decline after a longer period of incubation, suggesting the participation of docosahexaenoyl‐phosphatidic acid in the synthesis of other glycerolipids. It was acylated primarily into phosphatidylcholine (PC) and phosphatidylethanolamine (PE) after a 2‐hr incubation. The labeled phosphatidic acid may be rapidly deacylated and the 22∶6(n−3) moiety is then reacylated into other lysophospholipids. The low levels of [14C]22∶6(n−3) in 1,2‐diacylglycerol suggest that the deacylation‐reacylation cycle may be a major pathway in the formation of [14C]22∶6(n−3)‐PC and‐PE in intact neutrophils. This n−3 fatty acid was a relatively poor substrate for acylation into phosphatidyl‐inositol as compared to arachidonic acid and eicosapentaenoic acid. However, the patterns of distribution of all three polyunsaturated fatty acids among the diacyl‐and ether‐linked class compositions of PC and PE were similar. These data suggest the potential of increasing the content of docosahexaenoic acid of membrane lipids in neutrophils by dietary supplement of this fatty acid.
Change of substrate specificity of rat liver microsomal fatty acyl‐CoA synthetase activity by triton X‐100
Authors: Nagamatsu Kunisuke , Soeda Shinji , Kishimoto Yasuo
Published: December 2006

The effect of Triton X‐100 on the activities and apparent molecular size of fatty acyl‐CoA synthetase, solubilized and partially purified from rat liver microsomes, was studied. In the presence of Triton X‐100, the activity for lignoceroyl‐CoA synthesis was decreased, but activity was restored when the detergent was removed. The appearance and disappearance of lignoceroyl‐CoA synthesis appeared related to the size, of the aggregated from of the enzyme. On the other hand, activity for palmitoyl‐CoA synthesis was not significantly affected by the detergent. Because available evidence suggests that both fatty acids are converted to CoA esters by the same enzyme, it seems likely that the substrate specificity of the enzyme is influenced by changes in the aggregation state branes may determine the substrate specificity of acyl‐CoA synthetase.
Chemical lonization‐mass spectrometry of secondary oxidation products from methyl linoleate and linolenate
Authors: Frankel E. N. , Neff W. E. , Plattner R. D.
Published: December 2006

Chemical ionization‐mass spectrometry (CI‐MS) with a direct exposure probe was used to analyze a series of hydroperoxy cyclic peroxides and dihydroperoxides obtained from methyl linoleate and linolenate by either autoxidation or photosensitized oxidation. The mass spectra obtained with isobutane and ammonia as reacting gases showed fragmentation patterns similar to those ditions of gas chromatography (GC)‐electron impact (EI)‐MS. Because the fragmentation patterns obtained under either CI‐MS with a direct exposure probe or GC‐(EI)‐MS conditions are sufficiently predictable, these techniques are powerful analytical tools for the structural characterization of lipid oxidation products. These techniques are also useful to elucidate the cleavage pathways to volatile lipid oxidation products of flavor and biological significance.
Quantitative analysis of polyenoic phospholipid molecular species by high performance liquid chromatography
Authors: Takamura Hitoshi , Narita Hiroshi , Urade Reiko , Kito Makoto
Published: December 2006

The quantitative analysis of phospholipid molecular species containing polyenoic fatty acids is described. Dinitrobenzoyl derivatives of diacylglycerols prepared from phospholipids were separated into individual molecular species by reversed‐phase high performance liquid chromatography (HPLC) using a combination of two solvent systems and were quantified at 254 nm. Thirty‐six molecular species were resolved from the phosphatidylcholines of rat hearts, human platelets and Chinese hamster V79‐R cells. The derivatives of alkenylacyl molecular species from platelet phosphatidylethanolamine were resolved concomitantly with diacyl molecular species.
Fast atom bombardment and tandem mass spectrometry for determing iso‐ and anteiso‐fatty acids
Authors: Jensen Nancy J. , Gross Michael L.
Published: December 2006

Branched fatty acids can be distinguished from isomeric straight chain fatty acids by collisionally activating the (M‐H)− ions desorbed by using fast atom bombardment (FAB) mass spectrometry (MS). In particular, an acid with iso‐ fatty branching can be readily distinguished from one containing anteiso‐ branching; the latter undergoes loss of the elements of CH4 and C2H6 but not C3H8. These decompositions are another example of remote charge site fragmentation. Mixtures of homologs and isomers can be investigated by using the combination of FAB and tandem mass spectrometry (MS‐MS).
Stimulation of fatty acid synthesis by 4β‐phorbol‐12‐myristate‐13‐acetate in isolated rat hepatocytes
Authors: Nomura Takahide , Tachibana Masakatsu , Nomura Hiroko , Hagino Yasumichi
Published: December 2006

The tumor‐promoting agent 4β‐phorbol‐12‐myristate‐13‐acetate (TPA) is shown to be a potent stimulator of fatty acid synthesis in isolated rat hepatocytes. The maximal effect of TPA is seen at 10−6 M, and the concentration for half‐maximal effect is ca. 10−8 M. Stimulation of fatty acid synthesis by TPA is shown not to require the presence of extracellular Ca++. TPA produces a significant increase in lactate and pyruvate accumulation. The possible involvement of protein kinase C in short‐term regulation of fatty acid synthesis in the liver is discussed.
Effects of triarimol and tridemorph on sterol biosynthesis inSaprolegnia ferax
Authors: Berg Linda R. , Patterson Glenn W. , Lusby William R.
Published: December 2006

The effects of two fungicides, triarimol and tridemorph, on sterol biosynthesis inSaprolegnia ferax were examined. Cultures grown in the presence of triarimol accumulated lanosterol. Tridemorph‐treated cultures accumulated Δ8‐sterols including zymosterol, fecosterol and stigmasta‐8‐24(28)‐dienol. The latter is a new sterol. A proposed scheme is given for sterol biosynthesis inS. ferax showing points of inhibition of triarimol and tridemorph. Results point to the intermediacy of lanosterol but not cycloartenol in sterol synthesis inSaprolegnia.
Systematic protocol for the accumulation of fatty acid data from multiple tissue samples: Tissue handling, lipid extraction and class separation, and capillary gas chromatographic analysis
Authors: Maxwell Robert J. , Marmer William N.
Published: December 2006

A systematic procedure was developed for detailed fatty acid profiling of both neutral and polar lipid fractions isolated from hundreds of related bovine muscle and adipose tissue samples. A regimen was established for a nonbiased handling of tissue samples, which included their handling in a predetermined random order. Lipid class separation was accomplished concomitantly during the extraction of the tissues by a selective dry column method, which allowed a detailed analysis of minor but important polyunsaturated fatty acids associated with the polar fraction. Neutral lipids were derivatized to fatty acid methyl esters (FAME) by a literature procedure. However, to protect against lysis of plasmalogens in the polar fraction, a modified nonacidic esterification procedure was developed. FAME profiles were obtained on a program‐mable high resolution capillary gas chromatograph (GC). Run programs for unattended GC operation and data storage are described. By this overall procedure, the quantitation and peak identification were obtained for major and minor fatty acid constituents from bovine tissue in a manner that prepares for valid statistical interpretation of the resulting data.
Systematic management and analysis of fatty acid data from multiple tissue samples
Authors: Marmer William N. , Maxwell Robert J. , Phillips John G.
Published: December 2006

A systematic approach has been developed for the collection and analysis of gas chromatographic (GC) data from multiple fatty acid profiles. The approach was applied to a series of polar and nonpolar tissue lipids generated in animal feeding studies to allow a comparison of mean fatty acid profiles as a function of either dietary regimen or tissue location. The magnitude of the studies, sufficiently large to minimize error from animal variabilities, mandated the use of computer assistance. Nevertheless, manual input was essential due to the complexity of the GC patterns, and was invoked for peak assignment and report editing. The approach discussed here allowed for the consolidation and statistical analysis of data from over 30,000 GC peaks, and generated results in both tabular and graphic formats. It should be extendable to other chromatographic studies of lipid components.
Role of membrane lipids in the immunological killing of tumor cells: I. Target cell lipids
Authors: Schlager Seymour I. , Ohanian Sarkis H.
Published: December 2006

The metabolic and physical properties of tumor cells that are associated with their ability to resist or escape from immune attack have been investigated. The susceptibility of P815 murine‐mastocytoma cells to immune killing can be modulated. Culturing the cells with adriamicin or with hydrocortisone increases or decreases, respectively, the sensitivity of the cells to killing by antibody (Ab) plus complement (C); in addition, culturing the cells with mitomycin C or hydrocortisone increases or decreases, respectively, the sensitivity of the cells to killing by cytotoxic T lymphocytes (CTL). The susceptibility of the cells to Ab‐C killing correlates with the ability of the cells to synthesize complex cellular lipids, but not DNA, RNA, protein, or carbohydrate. Further, tumor cells rendered sensitive to Ab‐C killing by adriamycin are decreased in total lipid content and in their cholesterol/phospholipid mole ratio; hydrocortisone‐treated resistant cells showed the opposite effects. The ability of tumor cells to resist CTL killing did not correlate with their total cellular lipid synthesis, but did correlate with the synthesis and composition of specific cellular phospholipids. In addition, tumor cells increased in sensitivity to Ab‐C killing exhibited an increase in cell surface membrane fluidity, whereas cells increased in suceptibility to CTL attack showed an increase in their net negative cell surface charge density. These data show certain unique chemical and physical properties of tumor cells to be of fundamental importance for their ability to resist either humoral or cell‐mediated immunologic attack; modulation of one or another of these cellular properties results in a change in the cells' susceptibility to immune killing by antibody plus C or by cytotoxic T lymphocytes.
Role of membrane lipids in the immunological killing of tumor cells: II. Effector cell lipids
Authors: Schlager Seymour I. , Meltzer Monte S. , Madden Lawrence D.
Published: December 2006

Peritoneal macrophages (MØ) from mice become cytotoxic after incubation in lymphokine (LK)‐rich supernatants of antigen‐stimulated spleen cell cultures. Tumoricidal activity is evident with MØ treated with LK for 4 hr, becomes maximal after 8–12 hr incubation and decreases to control levels by 24–36 hr. To gain insight into LK‐induced functional changes, the lipid composition of MØ cultured with LK for 0–36 hr was analyzed by high pressure liquid chromatography. LK induced marked changes in MØ lipid composition: cellular content of cholesterol (CHOL) and polyunsaturated fatty acids increased 2‐ to 3‐fold after 8 hr when the cells showed maximal tumoricidal activity. Cellular lipid and fatty acid content returned to control levels by 24 hr when the MØ had lost tumoricidal activity. These changes were not observed with equal numbers of MØ cultured in control supernatants. To analyze further the role of CHOL and unsaturated fatty acids in MØ tumor cytotoxicity, MØ were enriched in CHOL or linolenic acid (18∶3) and tested for their ability to kill 1023 tumor cells. Within 1 hr of culture, MØ showed a 3‐ to 4‐fold increase in CHOL or 18∶3 content. 18∶3‐enriched cells were markedly tumoricidal, whereas controls cultured in delipidized medium alone or enriched with saturated fatty acid were not cytotoxic. CHOL‐enriched MØ were not tumoricidal; indeed, these cells were inhibited in their killing after treatment with LK compared to MØ cultured in delipidized medium with LK alone. These results suggest that UFA aids, whereas CHOL negates, expression of MØ tumor cytotoxicity.
The role of neutral glycolipids and phospholipids in myxovirus‐induced membrane fusion
Authors: Huang Richard T. C.
Published: December 2006

Myxoviruses (influenza virus and paramyxovirus) enter host cells by two successive steps consisting of attachment and fusion between viral and cellular membranes. The initial attachment is known to occur through specific binding of the viruses with the neuraminic acid‐containing receptors of cellular membranes. Evidence is presented here that, in the following step of membrane fusion, neutral glycolipids terminating in galactose and certain phospholipids (primarily lecithin and sphingomyelin) interact with the viral envelopes and that this interaction may be fundamental to the fusion process.
Isolation and characterization of the monounsaturated long chain fatty acids ofMycobacterium tuberculosis
Authors: Takayama Kuni , Quereshi Nilofer , Schnoes Heinrich K.
Published: December 2006

The positions of double bond in the monounsaturated C15−C32 fatty acids ofMycobacterium tuberculosis H37Ra were established by gas chromatography/mass spectrometry of the ozonized esters and their pyrrolidide derivatives. The monounsaturated C15−C21 fatty acids had the double bond primarily at the Δ9 position while the monounsaturated longer chain fatty acids (C22−C32) had the double bond in several positions. Many of the latter acids, especially the odd‐numbered series, were very complex isomeric mixtures. Quantitation showed the most abundant even‐numbered long chain fatty acid isomers to be as follow: C22, Δ4; C24, Δ5; C26, Δ7 and Δ9; C28, Δ9; C30, Δ11 and Δ13; C32, Δ13 and Δ15.
Models for lipid organization in cholesterol‐phospholipid bilayers including cholesterol dimer formation
Authors: Martin R. Bruce , Yeagle Philip L.
Published: December 2006

Three new structural models, which account for abrupt changes in physical properties observed at several molar concentrations of cholesterol in phospholipid bilayers, are described. Cholesterol monomers, each surrounded by its own envelope of unshared acyl hydrocarbon chains of the phospholipid, can accommodate 22% cholesterol. Cholesterol dimers, each surrounded by its own envelope of unshared acyl hydrocarbon chains, can accommodate 31% cholesterol. When surrounded by shared acyl hydrocarbon chains, cholesterol dimers can accommodate about 47% cholesterol. At greater concentrations, cholesterol aggregation occurs, the system is unstable, and cholesterol forms a separate phase.
Sterol metabolism studies in rats: Effects of taurodeoxycholic acid feeding on sterol metabolism
Authors: Franklin Raicht Robert , Cohen Bertram Ira , Eliav Bess , Heinz Mosbach Erwin
Published: December 2006

Sterol metabolism studies using isotopic and chromatographic techniques were carried out in: (a) control rats fed stock chow +0.1% cholesterol (control group), and (b) rats fed stock chow +0.1% cholesterol and supplemented with 0.5% sodium taurodeoxycholate (taurodeoxycholate group). Feeding the bile acid enriched diet led to decreased acidic steroid synthesis, decreased cholesterol turnover, and cholesterol balance compared to nonsupplemented controls. There were no significant differences in fecal neutral sterol output, endogenous neutral sterol output, or cholesterol absorption between bile acid fed animals and controls. Tissue cholesterol levels (liver, plasma, and bile) in the two groups were also similar.
The influence of purines on plasma lecithin: Cholesterol acyltransferase activity in the rat
Authors: Solera M. L. , Dousset N. , Valdiguie P. , Douste‐Blazy L.
Published: December 2006

The activity of plasma lecithin: cholesterol acyltransferase (LCAT) in the rat is significantly inhibited in vitro by guanine, xanthine, and hypoxanthine. LCAT activity decreases with increase in xanthine concentration. The other two purines, adenine and uric acid, had no significant effect.
Isolation and analysis of age‐related fluorescent substances in rat testes
Authors: Shimasaki Hiroyuki , Ueta Nobuo , Privett O. S.
Published: December 2006

Fluorescent substances were extracted from rat testicular tissue with 2,2‐dimethoxypropane (DMP) and analyzed by 2‐dimensional thin layer chromatography (TLC). One substance that accumulated with increasing age of the animals was isolated and analyzed quantitatively by spectrophotofluorometry using quinine sulfate as a standard. This substance, which was designated as an age‐related fluorescent substance (ARFS), exhibited an excitation maximum at 355 nm and an emission maximum at 490 nm. Its fluorescence was quenched by metal chelators and at alkaline pH, indicating it contained a conjugated Schiff base structure. Quantitative analysis of this substance in the testes of rats 1, 2, 11 and 20 months of age showed that it increased linearly with age. The relation of this substance to aging also was indicated by its detection in animals of different ages fed diets of both low and high unsaturation.
Essential fatty acid restriction inhibits vitamin D‐dependent calcium absorption
Authors: Hay A. W. M. , Hassam A. G. , Crawford M. A. , Stevens P. A. , Mawer E. B. , Jones F. Sutherland
Published: December 2006

Essential fatty acid (EFA) restriction has been found to inhibit the action of vitamin D on the active transport of calcium in the intestine. This inhibition suggests EFAs are involved in facilitating the active transport of calcium across the mucosal membrane.
Mitochondrial metabolism of (D,L)‐threo‐9, 10‐dibromo palmitic acid
Authors: Mohamed H. F. , Andreone T. L. , Dryer R. L.
Published: December 2006

Bromination of palmitoleic or palmitelaidic acid proceeds bytrans addition and yields dibrominated products which cannot undergo β‐oxidation when incubated with mitochondria isolated from hamster brown adipose tissue. These mitochondria were selected because they have a high capacity for oxidation of C16 fatty acids and because they are readily uncoupled by an excess of free fatty acids of this chain length. The only metabolites which could be recovered from the incubation mixtures were dibromopalmitoylcarnitine and dibromopalmitoyl CoA. Free fatty acid was also recovered. Addition of synthetic carnitine or CoA esters of brominated fatty acids did not interfere with subsequent oxidation of palmitoylcarnitine. Addition of the free brominated fatty acids did significantly increase the rate of oxidation of subsequent additions of palmitoylcarnitine, as did other known synthetic uncouplers. These results are consistent with observations by others that feeding brominated oils leads to brominated fatty acid incorporation into tissue lipids, and indicate why this is so. They also provide a possible explanation for the hepatic damage noted in feeding experiments.
Effect of ethanol administration on fatty acid desaturation
Authors: Nervi Anibal Mario , Peluffo Raul Omar , Brenner Rodolfo R. , Leikin Alicia Isabel
Published: December 2006

The effect of ethanol on the fatty acid desaturation by rat liver has been studied using liquid diets of different composition. Acute ethanol administration increased triacylglycerols of total liver lipids, but did not modify significantly the lipidic composition of microsomes. The Δ6 and Δ5 desaturases were inhibited by ethanol whereas the Δ9 desaturase and fatty acid synthetase were apparently modified only by diet composition. NADH‐cytochrome (cyt.) c reductase was partially inhibited, whereas NADH‐cyt. b5 reductase remained practically unaltered and NADPH‐cyt. c reductase activity was enhanced. Decreased electrons supplied by the microsomal cyt. b5 electron transport chain would not be the reason for the inhibition of Δ6 and Δ5 desaturases by ethanol.
A single‐step method for determination of the specific radioactivity of lipids
Authors: Noble R. C. , Shand J. H.
Published: December 2006

The use of a liquid scintillation counter to measure both the mass and the radioactivity content of charred14C‐labeled lipid bands from thin layer chromatoplates has been evaluated. Following lipid mass determination from a measurement of the external standard channels ratio, a suitable choice of counting parameters enabled a reproducible and efficient14C count to be obtained over virtually the whole range of lipid concentrations tested. Although the charring procedure resulted in some loss of radioactivity, the efficiency of counting remained high enough for accurate dpm measurements.
The effect of dietary fat on the fatty acid composition of lipids secreted in rats' milk
Authors: Brandorff Nanna Philipson
Published: December 2006

During pregnancy and lactation, female rats were fed diets containing either 28% partially hydrogenated marine oil (28MO), 2% arachis oil (2AO), or no fat (FF). Milk lipid composition was examined by gas chromatographic analysis of the gastric content of 10‐day‐old suckling pups. An increase to 45% in the milk content of long chain monoenoic acids, 18∶1, 20∶1 and 22∶1, reflects the fatty acid composition of the marine oil. Milk fatty acids of medium chain length comprised 6%, 31% and 24% of total fatty acids in the (28MO), (2AO) and (FF) groups, respectively, suggesting that a high‐fat diet (28MO) inhibits the lipid synthetic activity of mammary glands. The amount of dienoic C18‐acids (6%) in the group fed (28MO) containing no essential fatty acids (EFA) was similar to the amount of 18∶2 in the group receiving a low‐fat, EFA‐rich diet (2AO). However, only half the dienoic acid from the milk of the (28MO)‐fed animals was linoleic acid, which was most likely mobilized from fat depots.
Complex formation in sonicated mixtures of β‐lactoglobulin and phosphatidylcholine
Authors: Brown Eleanor M. , Carroll Robert J. , Pfeffer Philip E. , Sampugna Joseph
Published: December 2006

β‐Lactoglobulin, the major whey protein of bovine milk, is secreted via the endomembrane system of the mammary gland. The primary structure of β‐lactoglobulin shares certain characteristics with membrane proteins, although the soluble protein assumes a globular conformation. We have prepared complexes of β‐lactoglobulin and phosphatidylcholines by dissolving both in a helix‐forming solvent (chloroform methanol). The complex is stable when transferred to aqueous solutions and sonicated to form vesicles. Both ionic and hydrophobic interactions appear to be involved in complex formation. We have used spectroscopy (circular dichroism, fluorescence, and nuclear magnetic resonance) and electron microscopy to study these complexes. At pH 3.7, the small, single bilayer vesicles produced by sonication are protected against aggregation by the presence of the protein. As determined by circular dichroism, the proportion of α‐helix in β‐lactoglobulin is increased by complexation with phosphatidylcholine. Circular dichroism and fluorescence spectra show the involvement of at least 1 tryptophan residue in the conformational change. At pH 7.2, β‐lactoglobulin‐phosphatidylcholine vesicles form aggregates as observed by electron microscopy and31P nuclear magnetic resonance spectroscopy. These aggregated vesicles could be resuspended by raising the pH. The ability of the partially unfolded β‐lactoglobulin to interact with lipids is believed to be important to its transport through the endomembrane system.
The influence of chenodeoxycholic acid on cholesterol and bile acid turnover in humans with cholelithiasis
Authors: Quarfordt S. H. , Jain R. , Greefield M. R.
Published: December 2006

The in vivo dynamics of cholesterol were determined in 8 individuals who were part of a national double‐blind study testing the efficacy of chenodeoxycholic acid ingestion on the dissolution of gallstones. Despite the ingestion of this bile acid in amounts in excess of its normal endogenous flux, the conversion of neutral sterol to chenodeoxycholic acid continued. The flux of neutral sterol to endogenous chenode‐oxycholate was lower for the patients ingesting bile acid than for one of the patients on placebo, but was similar to that of the other control and similar to previously published chenodeoxycholate flux in patients with cholesterol cholelithiasis. The remaining flux was on the basis of the very efficiently absorbed dietary chenodeoxycholate. The total cholesterol fractional catabolic rate and flux were not appreciably diminished by the administration of either high or low dose chenodeoxycholate to these individuals with cholesterol cholelithiasis.
The influence of linoleic acid intake on the kinetics of adenine nucleotide translocase
Authors: Mak I. T. , Shrago E. , Elson C. E.
Published: December 2006

Dietary enrichment of mitochondrial polyenoic fatty acid content was associated with increased respiratory activity (Abuirmeileh and Elson). The influence of the membrane lipid composition on the adenine nucleotide translocase (AdNT) was studied in rats that were fed diets formulated with beef tallow (BT) to provide low or safflower oil (SO) to provide high contents of linoleic acid. The phosphatidylcholine/phosphatidylethanolamine ratio was 40% higher in the SO mitochondria due primarily to an increase in phosphatidylcholine. SO mitochondria exhibited 25% higher state 3 respiration, 50% higher state 4 respiration and 13% higher net ADP‐dependent respiration than did the BT mitochondria. The relative RCR and ADP/O values of the SO mitochondria were slightly but significantly (p<0.01) lower. The kinetics of the AdNT were determined by the back exchange method (Pfaff and Klingenberg). At all assay temperatures, SO mitochondria exhibited a higher Km for ADP. However, addition of 5 mM carnitine to the assay mixture increased the affinity of the SO‐AdNT giving Km values similar to that of the BT‐AdNT. Washing the mitochondria with fat‐free BSA had a similar, but lesser, effect. At 25 C and 37 C, the Vmax of the SO‐AdNT were increased by 11–15% (p<0.05) which was independent of either BSA‐wash or the presence of carnitine. According to Dixon plot studies, the SO‐AdNT had a comparable Ki for atractylate but a slightly lower Ki for palmitoyl‐CoA inhibition. The accumulation of acyl‐CoA esters in the SO mitochondria was not ruled out. The overall results suggest that changes in mitochondrial membrane lipids accommodated an increased Vmax of the SO‐AdNT, which in turn accounted for that part of the increased state 3 respiration dependent on ADP translocation.
Effects of site‐directed mutagenesis on the serine residues of human lecithin: Cholesterol acyltransferase
Authors: Qu Shi‐Jing , Fan Hui‐Zhen , Blanco‐Vaca Francisco , Pownall Henry J.
Published: December 2006

Lecithin:cholesterol acyltransferase (LCAT) is a serine protease‐type enzyme that esterifies cholesterol in human plasma and is activated by apolipoprotein A‐I in high‐density lipoproteins. LCAT contains 22 serine residues, including Ser 181, which is thought to be part of the catalytic site. In order to determine the importance of these serine residues in LCAT, we prepared six LCAT mutants: LCAT (Ser19→Ala), LCAT (Ser181→Gly), LCAT (Ser208→Ala), LCAT (Ser216→Ala), LCAT (Ser225→Ala) and LCAT (Ser383→Ala). We also replaced the adjacent asparagine residues in two additional mutants, LCAT (Ser19→Ala, Asn20→Thr) and LCAT (Ser383→Ala, Asn384→Thr), in order to ascertain the effect of the serines onN‐glycosylation. The mutant complementary DNA (cDNA) were subcloned into a eukaryotic expression vector (pSG5) and expressed in COS‐6 cells. By polymerase chain reaction analysis, LCAT‐specific messenger RNA (mRNA) was found in all mutant and wild‐type transfectants. Western blot analysis revealed LCAT‐specific bands in media and lysates of the transfected cells. With two exceptions, the amounts of LCAT mass secreted by the transfectants were similar to that of the wild type (mean, 90% mass of wild type; range, 34–138%). Except for LCAT (Ser181→Gly), which was inactive, the specific activities of the remainder of the mutant enzymes were also similar (mean, 95% activity of wild type; range, 65–169%). These results indicate that Ser181 is part of the catalytic site and that stereoconservative substitutions for serines have minor effects on the synthesis, secretion and specific activities of human LCAT.
Interactions of MDL 29,311 and probucol metabolites with cholesteryl esters
Authors: McLean Larry R. , Brake Nick , Hagaman Karen A.
Published: December 2006

The hypothesis that the efficacy of hydrophobic antioxidants in animal models of atherogenesis may, in part, be related to physical effects on cholesteryl esters in cells was probed with analogs and metabolites of probucol. The interactions of an effectivebis‐thiomethane analog (MDL 29,311) and selected metabolites of probucol with cholesteryl oleate were examined by differential scanning calorimetry and polarized light microscopy. Like probucol, MDL 29,311 and the bisphenol metabolite decrease the liquid‐crystalline phase transition enthalpy of cholesteryl oleate with increasing concentrations. At 20 mol%, no transition is detectable. By contrast, the spiroquinone metabolite of probucol and the diphenoquinone metabolite common to both molecules have minimal effects on the liquid‐crystalline transitions of cholesteryl oleate. At 20 mol%, neither compound has as great an effect as 1 mol% MDL 29,311. Consistent with their effects on dry cholesteryl oleate, MDL 29,311 and the bisphenol metabolite convert lipid inclusions in cells supplemented with cholesterol to an isotropic physical state similar to that observed with probucol. The number of anisotropic inclusions in the cells decreases with increasing concentration in the medium in the range of 50 to 250 μg/mL. In cells fed with the spiroquinone or diphenoquinone metabolites, the lipid inclusions are liquid‐crystalline and resemble those observed with cholesterol‐fed controls. These data are interpreted in terms of a model in which hydrophobic antioxidants closely related to probucol disrupt the packing of cellular cholesteryl esters.
The n−3 polyunsaturated fatty acid levels in rat tissue lipids increase in response to dietary olive oil relative to sunflower oil
Authors: Navarro Maria D. , Periago José L. , Pita Maria L. , Hortelano Paloma
Published: December 2006

In the present study, changes in phospholipid compositions of liver microsomes, erythrocyte membranes, platelets, aorta, cardiac muscle and brain of rats fed olive oil were compared with those of rats fed sunflower oil. Four groups of rats starting at weaning were fed for four weeks a basal diet containing 5 or 25% olive oil or sunflower oil. We found that oleic acid was higher and linoleic acid was lower in membrane phospholipids of olive oil fed rats compared to sunflower oil fed rats. Polyunsaturated fatty acids of the n−3 series were markedly elevated in all tissues of rats on the olive oil diets relative to those on the sunflower oil diets. The results are consistent with a lower linoleic/linolenic acid ratio induced by the olive oil diets, suggesting a positive correlation between olive oil ingestion and n−3 polyunsaturated fatty acid levels in cell and tissue lipids. The study suggests that an adequate intake of olive oil may enhance the conversion of n−3 fatty acids.
Hematological and lipid changes in newborn piglets fed milk replacer diets containing vegetable oils with different levels of n−3 fatty acids
Authors: Kramer John K. G. , Sauer Frank D. , Farnworth Edward R. , Wolynetz Mark S. , Jones Gwynn , Rock Gail A.
Published: December 2006

To test if linolenic acid (18∶3n−3) from vegetable oils would affect bleeding times and platelet counts in new‐borns, piglets were used as a model fed milk replacer diets containing 25% (by wt) vegetable oils or oil mixtures for 28 d and compared to sow‐reared piglets. The oils tested included soybean, canola, olive, high oleic sunflower (HOAS), a canola/coconut mixture and a mixture of oils mimicking canola in fatty acid composition. All piglets fed the milk replacer diets showed normal growth. Bleeding times increased after birth from 4–6 min to 7–10 min by week 4 (P<0.001), and were higher in pigs fed diets containing 18∶3n−3, as well as in sowreared piglets receiving n−3 polyunsaturated fatty acids (PUFA) in the milk, as compared to diets low in 18∶3n−3. Platelet numbers increased within the first week in newborn piglets from 300 to 550×109/L, and remained high thereafter. Milk replacer diets, containing vegetable oils, generally showed a transient delay in the rise of platelet numbers, which was partially associated with an increased platelet volume. The oils showed differences in the length of delay, but by the third week of age, all platelet counts were >500×109/L. The delay in rise in platelet counts appeared to be related to the fatty acid composition of the oil, as the effect was reproduced by a mixture of oils with a certain fatty acid profile, and disappeared upon the addition of saturated fatty acids to the vegetable oil. There were no alterations in the coagulation factors due to the dietary oils. Blood plasma, platelets and red blood cell membranes showed increased levels of 18∶3n−3 and long‐chain n−3 PUFA in response to dietary 18∶3n−3. The level of saturated fatty acids in blood lipids was generally lower in canola and HOAS oil‐fed piglets as compared to piglets fed soybean oil or reared with the sow. The results suggest that consumption of milk replacer diets containing vegetable oils rich in 18∶3n−3 does not represent a bleeding risk, and that the transient lower platelet count can be counterbalanced by the addition of saturated fatty acids to the vegetable oils.