bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

AbstractGlutathione 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

AbstractWhen 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

AbstractDocosahexaenoic 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

AbstractThe 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

AbstractChemical 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

AbstractThe 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

AbstractBranched 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

AbstractThe 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

AbstractThe 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

AbstractA 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

AbstractA 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

AbstractThe 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

AbstractPeritoneal 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

AbstractMyxoviruses (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

AbstractThe 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

AbstractThree 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

AbstractSterol 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

AbstractThe 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

AbstractFluorescent 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

AbstractEssential 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

AbstractBromination 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

AbstractThe 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

AbstractThe 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.