bluuebunny/crossref_metadata_2025 huggingface dataset:
Indomethacin stimulation of lipid peroxidation and chemiluminescense in rat liver microsomes
Authors: Pennington S. N. , Smith C. P.
Published: November 2006

Peroxidation of endogenous lipid by rat liver microsomes, coupled with oxidation of reduced nicotinamide adenine dinucleotide phosphate (NADPH) and measured as thiobarbituric acid reactive materials, is markedly stimulated in the presence of indomethacin [1‐(p‐chlorobenzyl)‐5‐methoxy‐2‐methyl‐3‐indole acetic acid] (0.1–1.0 mM). Concurrently, indomethacin enhances the lipolysis of membrane phospholipid containing arachidonic acid but has no effect on the rate of O2 uptake in these samples. The system generates a rapidly developed chemiluminescense (CL), the intensity and rate of development of which are related to indomethacin concentration. The microsomal CL generated in the presence of indomethacin is distinct from the previously reported CL in that the time required for maximum intensity development is a matter of seconds (20–180) rather than hours. The enhanced CL is believed to be due to an energy transfer reaction whereby a high energy species transfers energy to the indomethacin molecule, which, in turn, decays via chemiluminescense. An enhanced chemiluminescense was also observed when indomethacin was added to a lipoxidase system and superoxide generating system (xanthine oxidase). Based on inhibitor studies, the rapidly developed chemiluminescense of the microsomal system requires cytochrome P‐450 in addition to NADPH and coordinated iron ions. The results indicate that the CL is related to neither hydroxyl free radical nor superoxide anion formation.
The content and composition of sterols and sterol esters in low erucic acid rapeseed (Brassica napus)
Authors: Johansson Anna , Appelqvist Lars‐Åke
Published: November 2006

The low temperature crystallization technique for the enrichment of “minor” components, such as sterols and sterol esters, from vegetable oils was applied to low erucic acid rapeseed oils. The recovery of free sterols and sterol esters was estimated by use of14C‐cholesterol and14C‐cholesterol oleate. 80% of the free sterols and 45% of the sterol esters were recovered in the liquid fraction, while in two studies total recoveries were 95% and 99%, respectively. This technique showed some selectivity toward the sterol bound fatty acids when compared to direct preparative thin layer chromatography (TLC) of the crude oil. Gas liquid chromatography (GLC) analysis of the free and esterified sterols as TMS‐derivatives showed very little selectivity in the enrichment procedure. The fatty acid patterns of the sterol esters demonstrated, however, a preference in the liquid fraction for those sterol esters which have a high linoleic and linolenic acid content. The content of free sterols was 0.3–0.4% and that of sterol esters 0.7–1.2% of the rapeseed oils in both winter and summer types of low erucic acid rapeseed (Brassica napus) when the lipid classes were isolated by direct preparative TLC of the oils. The free sterols in the seven cultivars or breeding lines analyzed were composed of 44–55% sitosterol, 27–36% campesterol, 17–21% brassicasterol, and a trace of cholesterol. The esterified sterols were 47–57% sitosterol, 36–44% campesterol, 6–9% brassicasterol, and traces of cholesterol and Δ5‐avenasterol. The fatty acid patterns of these esters were characterized by ca. 30% oleic acid and ca. 50% linoleic acid, whereas these acids constitute 60% and 20%, respectively, of the total fatty acids in the oil. Little or no variation in sterol and sterol ester patterns with locality within Sweden was observed for the one cultivar of summer rapeseed investigated by the low temperature crystallization technique.
Composition of lipids of bovine optic nerve
Authors: Das S. K. , Steen M. E. , McCullough M. S. , Bhattacharyya D. K.
Published: November 2006

Lipids from bovine optic nerve were analyzed. The total content of 16.5% by weight included 27.2% nonpolar lipids, 26.1% glycolipids, and 46.7% phospholipids by weight. Free cholesterol was the major component of the nonpolar lipid fraction. The cerebrosides, 73.5% of total glycolipids, were separated by thin layer chromatography (TLC) into two bands (upper and lower) that were present in equal proportion. Cerebroside sulfates comprised about 27.5% of total glycolipids. Gangliosides were also detected in the glycolipid fraction. In order of predominance, choline glycerophospholipids, ethanolamine glycerophospholipids, ethanolamine plasmalogens, serine glycerophospholipids, sphingomyelins, and inositol glycerophospholipids were the major phospholipids. Palmitoyl (16∶0), stearoyl (18∶0), and oleoyl (18∶1) groups were the major acyl groups in all neutral and phospholipid classes. However, ethanolamine glycerophospholipids, serine glycerophospholipids, and inositol glycerophospholipids contained a large percentage of 22∶6 (docosahexaenoyl) group. The major alk‐1‐enyl groups of the plasmalogens were 16∶0, 18∶0, and 18∶1. Steroyl (18∶0), lignoceroyl (24∶0), and nervonoyl (24∶1) were the major acyl groups in all sphingolipids. Lower cerebroside band and cerebroside sulfates contained large amount of hydroxylignoceroyl (cerebronoyl) and hydroxynervonoyl groups.
The steric requirements for sterol inhibition of tetrahymanol biosynthesis
Authors: Conner Robert L. , Landrey Josephine R. , Joseph John M. , Nes William R.
Published: November 2006

Many naturally occurring sterols are accumulated and metabolized byTetrahymena pyriformis. In most cases, the sterols are desaturated to giveΔ5,7,22‐derivatives. Compounds with an ethyl, but not with a methyl, substituent at C‐24 are dealkylated. Exposure of the ciliates to the appropriate sterol sharply curtails the synthesis of the native pentacyclic triterpenoid alcohols, tetrahymanol and diplopterol. An analysis with modified sterols has revealed several additional features that are required for desaturation at C‐7,8 and C‐22,23 and for inhibition of tetrahymanol biosynthesis. The presence of atrans‐17(20)‐double bond, which eliminates free rotation at C‐20 and fixes C‐22 to the right of the nucleus, does not interfere with desaturation, while thecis‐ or left‐handed isomer is not metabolized. Thecis‐Δ17(20)‐isomer is, however, an effective inhibitor of tetrahymanol biosynthesis, although less so that thetrans‐counterpart. When a methyl or hydroxyl group at C‐20 protrudes to the front of the molecule in the right‐handed conformation, metabolism is reduced or abolished. Shortening (by one C‐atom) or lengthening of the sterol side chain has little effect on the ability of the compounds to inhibit tetrahymanol biosynthesis or to support growth, as long as the overall length of the side chain does not exceed seven carbons from C‐20. The presence of a 7α‐, 7β‐, 20α‐, 20β‐, or a 25‐hydroxy group in the cholesterol molecule sharply inhibits desaturation and curtails the effectiveness of the compound as an inhibitor of tetrahymanol biosynthesis. The 7‐ or 22‐keto derivatives seem to act in a fashion similar to the hydroxy derivatives, but these compounds show greater inhibition of growth. 20‐Methylcholesterol, however, is a potent inhibitor of synthesis, which suggests that the polarity of the substituent of C‐20 is more important than bulk. Many sterols can effectively replace tetrahymanol in the membranes of these ciliates. However, several of the compounds, which inhibit synthesis, appear to be physiologically inappropriate, and poor growth results. An example of the latter class is 20‐methylcholesterol. Finally, a class of sterols, represented by 20α‐hydroxycholesterol and 7‐ketocholesterol, does not severly inhibit tetrahymanol synthesis but leads to growth inhibition and surface abnormalities. These sterols apparently lead to a disordered membrane, even in the presence of tetrahymanol.
Inhibition of cholesterol synthesis by oxygenated sterols
Authors: Kandutsch Andrew A. , Chen Harry W.
Published: November 2006

Sterols derived from cholesterol by introducing a ketone or hydroxyl function in the 6, 7, 15, 20, 22, 24, or 25 positions are known to be potent inhibitors of sterol synthesis in cell cultures. To gain more information regarding structural requirements for inhibitory activity, inhibitory potencies were determined for a series of 18 C27‐steroids with various combinations of ketone and hydroxyl functions substituted in positions 3, 4, 5, 6, and 7, or with a single ketone or hydroxyl function in one of these positions. The effects of nuclear double bonds upon inhibitory activity were also examined. A ketone or hydroxyl function in position 3 and a second ketone or hydroxyl function in position 6 or 7 was required for inhibitory activity with two kinds of cell culture. A 3β5α6β‐triol was not more inhibitory than a comparable 3β,6β‐diol. Cholestance‐3β 5α‐diol inhibited sterol synthesis in L cells but not in liver cell cultures. The inhibitory activities of 7‐oxygenated sterols were not markedly affected by the presence of a double bond in position 4 or 5. Current knowledge of the mechanism through which the oxygenated sterols suppress cholesterol synthesis is reviewed.
Cyclopamine and related steroidal alkaloid teratogens: Their occurrence, structural relationship, and biologic effects
Authors: Keeler Richard F.
Published: November 2006

A spontaneous congenital deformity is produced in lambs whose dams consumeVeratrum californicum on the 14th day of gestation. The deformity is generally expressed as cyclopia, cebocephaly, anophthalmia, or microphthalmia. This teratogenic effect is produced by certain steroidal alkaloid teratogens from the plant—most notably the compound cyclopamine. Cyclopamine is a C‐nor‐D‐homo steroid with fused furanopiperidine rings E and F at right angles to the plane of the steroid because of spiro attachment at C‐17 of the steroid. Among veratrum alkaloids, only those with an intact furan ring E were teratogenic in sheep, whereas those in which the piperidine ring is not rigidly positioned at right angles to the steroid were not. Many ruminants and laboratory animals are susceptible to the teratogen. It has wide species and tissue specificity and appears to have a direct effect on the embryo, not as a consequence of metabolic alteration of its structure nor as an indirect effect through a maternal influence. Other plant sources, notably potatoes, tomatoes, and eggplant contain related spirosolane steroidal alkaloids. Among naturally occurring spirosolanes, solasodine is teratogenic in hamsters, but neither tomatidine not diosgenin, the non‐nitrogen containing analog of solasodine, is teratogenic. Results of these and other studies suggest that a basic nitrogen positioned α with respect to the steroidal plane and at appropriate distance beyond the D ring confers the teratogenicity on the molecule. Potato sprouts with high alkaloid content are teratogenic in hamsters, but tubers and peels are not.
Metabolism of ether linked glycerolipids in dogfish (Squalus acanthias) serum: Evidence for resistance of ether bond to cleavage in 1‐alkyl‐2,3‐diacylglycerols
Authors: Malins Donald C. , Robisch Paul A.
Published: November 2006

Rac‐[1‐14C]‐palmitylglycerol (chimyl alcohol), rac‐[1‐14C]‐palmityl‐2,3‐dioleoylglycerol, and rac‐palmityl‐2,3‐[9, 10‐3H]‐dioleoylglycerol were incubated with dogfish (Squalus acanthias) serum for periods of up to 15.0 hr. The ether bond of the carbon 14 labeled chimyl alcohol was cleaved readily, and radioactivity was incorporated into free fatty acids and the acyl chains of the major glycerolipids of the serum. In sharp contrast, the ether bond of the corresponding dioleoyl derivative remained virtually intact. However, the tritium from the acyl chains was incorporated into glycerolipids via intermolecular rearrangements of fatty acids. The findings are consistent with previous findings with rat liver microsomes showing that the ether linkages of alkylglycerolipids are resistant to oxidative cleavage when acyl groups are present on the glycerol moiety. However, substantial differences may exist between the conditions required for oxidative cleavage of the ether linkage of alkylglycerols in mammals and primative fish.
Studies of serum lecithin‐cholesterol acyl transferase activity in rat: Effect of vitamin E deficiency, oxidized dietary fat, or intravenous administration of ozondies or hydroperoxides
Authors: Takatori Takehiko , Privett O. S.
Published: November 2006

Serum lecithin‐cholesterol acyl transferase activity in the rat was studied in animals raised on diets devoid of vitamin E or containing oxidized fat and in the serum of normal animals after intravenous administration of hydroperoxides or ozonides. Lecithin‐cholesterol acyl transferase activity was suppressed by a vitamin E deficiency but was elevated in the serum of the animals fed diets containing oxidized fat. The intravenous injection of hydroperoxides or ozonides of linoleate into the tail vein of rats caused an immediate depression of serum lecithin‐cholesterol acyl transferase activity. The effect of hydroperoxides was more severe than the ozonides, but, with sublethal doses of these compounds, the activity of the enzyme became normal within 24 hr. Hydroperoxides and ozonides also suppressed the activity of lecithin‐cholesterol transferase of rat serum of normal animals in vitro. The suppression of lecithin‐cholesterol acyl transferase activity by hydroperoxides of ozonides was only partially restored by the addition to the serum of 2‐mercaptoethanol.
Rapid enzyme‐induced hydrolysis of microgram amounts of phosphatidylcholine on phospholipase A2/celite columns
Authors: Marmer William N. , Pietruszka Kathleen A.
Published: November 2006

A method has been developed to hydrolyze microgram amounts of phosphatidylcholine (PC) regiospecifically. Hydrolysis of thesn‐glycerol 2‐acyl group occurs rapidly on microcolumns of immobilized phospholipase A2 on Celite 545 diatomaceous earth. Close to 90% reaction occurs within the first 5 min. Acyl group analysis then may be accomplished by gas liquid chromatography (GLC) of the resulting fatty acids. Hydrolysis of α‐16∶0‐β‐14∶0 PC demonstrated consistent selectivity for 14∶0 liberation, with small amounts of 16∶0 probably indicative of acyl scrambling during the synthesis of the PC. Hydrolysis of an equal weight mixture of (14∶0)2 PC and (18∶2)2PC demonstrated nonpartiality of the immobilized enzyme for either a saturated or unsaturated substrate. The new methodology offers a convenient and sensitive alternative to the presently used procedures.
The occurrence of a furanoid fatty acid inHevea brasiliensis latex
Authors: Hasma H. , Subramaniam A.
Published: November 2006

Methyl esters from the triglyceride fraction of the neutral lipids of natural rubber latex were found by gas liquid chromatography to contain about 90% of a furanoid acid. Spectroscopic analysis identified the acid as 10,13‐epoxy‐11‐methyloctadeca‐10,12‐dienoic acid.
Separation of sulfated bile acids by high‐performance liquid chromatography
Authors: Goto Junichi , Kato Hiroaki , Nambara Toshio
Published: November 2006

In order to establish a new method for simultaneous determination of sulfated bile acids without deconjugation, separation of 3‐sulfates of unconjugated, glyco‐ and tauroconjugated bile acids by high‐performance liquid chromatography has been undertaken. The preliminary experiment indicated that reversed phase chromatography on an ODS SC‐02 column using ammonium carbonate aqueous solution/acetonitrile as a mobile phase would be promising. The ratio of peak width to retention time was varied depending upon the salt concentration. The content of water in mobile phase exerted an influence on the capacity ratio to a certain extent, but not on the resolution. The use of 0.5% ammonium carbonate/acetonitrile (26∶8 and 20∶8, v/v) was found to be suitable for complete resolution of sulfated cholate, chenodeoxycholate, deoxycholate, lithocholate and their glyco‐ and tauro‐conjugates.
Interaction of plasma high density lipoprotein HDL2b (d 1.063–1.100 g/ml) with single‐bilayer liposomes of dimyristoylphosphatidylcholine
Authors: Nichols Alex V. , Gong Elaine L. , Forte Trudy M. , Blanche Patricia J.
Published: November 2006

Incubation of a major subfraction, HDL2b (d 1.063–1.100 g/ml), of human plasma high density lipoproteins, HDL (d 1.063–1.21 g/ml), with single‐bilayer liposomes of dimyristoylphosphatidylcholine (DMPC) resulted in uptake of DMPC by the HDL2b and dissociation of lipid‐free apolipoprotein A‐I (apoA‐I). In the presence of excess DMPC, the dissociated apoA‐I was also incorporated with DMPC into discoidal complexes. Preliminary studies with model apoA‐I‐DMPC complexes indicated that they also can interact with native HDL2b with the resultant transfer of their DMPC to HDL2b and the concomitant release of their apoA‐I. After interaction of HDL2b with DMPC liposomes, the DMPC‐enriched HDL2b product showed a lower hydrated density and a larger particle size than the control HDL2b. The molecular properties of the lipoprotein product suggest that stabilization of the apoA‐I‐depleted HDL2b probably occurred via substitution of DMPC for the apoA‐I at the HDL2b surface rather than by fusion of the apoA‐I‐depleted HDL2b. The above interactions of HDL2b with single‐bilayer liposomes and discoidal complexes indicate pathways of phospholipid transfer relevant to the possible role of HDL in the metabolism of lipoprotein surface components in vivo.
Biosynthesis of chenodeoxycholic acid: Side‐chain hydroxylation of 5β‐cholestane‐3α,7α‐diol by subcellular fractions of guinea pig liver
Authors: Hoshita N. , Shefer S. , Cheng F. W. , Dayal B. , Batta A. K. , Tint G. S. , Salen G. , Mosbach E. H.
Published: November 2006

Side‐chain hydroxylation of 5β‐cholestane‐3α,7α diol was studied in subcellular fractions of guinea pig liver. The purity of the microsomal and the mitochondrial fractions was determined with marker enzymes, and relatively little cross contamination between the particulate fractions was detected. Methods for the analysis of the incubation mixture by thin‐layer chromatography and gas‐chromatography‐mass spectrometry were developed. Optimal assay conditions were established for the major hydroxylation reactions, namely the mitochondrial 26‐hydroxylation and the microsomal 25‐hydroxylation. It was found that the most active side‐chain hydroxylation in the guinea pig was the microsomal 25‐hydroxylation. The mitochondrial ω‐hydroxylation was stereospecific, in that the rate of formation of (25R)‐5β‐cholestane‐3α,7α,26‐triol was 8 times greater than that of the 25S isomer. The microsomal “26”‐hydroxylation was not stereospecific under the conditions employed. It is concluded that the mitochondrial “26” hydroxylation (leading to the formation of (25R)‐5β‐cholestane‐3α,7α,26‐triol) plays an important role in the biosynthesis of chenodeoxycholic acid. The participation of microsomal 25‐hydroxylation in the formation of chenodeoxycholic acids requires further investigation.
Dietary polyunsaturated fat versus saturated fat in relation to mammary carcinogenesis
Authors: Carroll K. K. , Hopkins G. J.
Published: November 2006

High levels of dietary fat have been shown to promote the development of mammary tumors induced in rats by 7,12‐dimethylbenz(α)anthracene, and polyunsaturated fats were found to be more effective than saturated fats. In further studies it was found that diets containing 3% sunflowerseed oil (polyunsaturated fat) and 17% beef tallow or coconut oil (saturated fats) enhance tumorigenesis as much as a diet containing 20% sunflowerseed oil. Rats on these diets developed at least twice as many tumors as those fed diets containing either 3% sunflowerseed oil or 20% of the saturated fats alone. These results are in accord with human epidemiological data which show that breast cancer mortality in different countries is positively correlated with total fat intake but not with intake of polyunsaturated fat. Total fat intake varies greatly in different countries, but most human diets probably contain levels of polyunsaturated fat at least equivalent to 3% sunflowerseed oil.
Linolenic acid deficiency
Authors: Tinoco J. , Babcock R. , Hincenbergs I. , Medwadowski B. , Miljanich P. , Williams M. A.
Published: November 2006

Linolenic acid deficiency has not been demonstrated clearly in warm blooded animals, yet circumstantial evidence suggests that n−3 fatty acids may have functions in these animals. The fact that several species of fish definitely require dietary n−3 fatty acids indicates that n−3 fatty acids have important and specific functions in these animals and suggests that such functions may also be present in warm blooded animals. It is also true that n−3 fatty acid distribution in tissues of birds and mammals appears to be under strict metabolic control, and that this complex metabolic control mechanism apparently has survived evolutionary pressure for a very long time. So far, attempts to produce linolenic acid deficiency in mammals have not revealed an absolute requirement for n−3 fatty acids. If functions for n−3 fatty acids do exist in warm blooded animals, it seems probable that they may be located in the cerebral cortex or in the retina, because these tissues normally contain high concentrations of n−3 fatty acids.
Polyunsaturated fatty acids, vitamine E, and the proliferation of aortic smooth muscle cells
Authors: Cornwell David G. , Huttner James J. , Milo George E. , Panganamala R. V. , Sharma H. M. , Geer Jack C.
Published: November 2006

Smooth muscle cell cultures were obtained from the aortas of prepubertal guinea pigs. Cell proliferation in these cultures was inhibited by 8,11,14‐eicosatrienoic acid, 5,8,11,14‐eicosatetraenoic acid, and their prostaglandin E derivatives, PGE1 and PGE2. Prostaglandin F derivatives, PGF1α and PGF2α, stimulated cell proliferation. Cell proliferation was also inhibited by 5,8,11‐eicosatrienoic acid and 11,14,17‐eicosatrienoic acid. The monoene and diene precursors of the triene acids, 9‐octadecenoic acid and 9,12‐octadecadienoic acid, did not inhibit cell, proliferation. Indomethacin alone had no effect on cell proliferation, and indomethacin did not suppress the inhibition of cell proliferation with a triene acid. The antioxidant α‐naphthol alone stimulated cell proliferation and suppressed prostaglandin E formation. α‐Naphthol in the presence of either triene or tetraene acids also stimulated cell proliferation and suppressed prostaglandin E formation. The antioxidants butylated hydroxy toluene and 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid either alone or in the presence of triene and tetraene acids stimulated cell proliferation and had no effect on prostaglandin E formation. Vitamin E either alone or in the presence of triene or tetraene acids stimulated cell proliferation and had no effect on prostaglandin E formation. More prostaglandin E was formed from 8,11,14‐eicosatrienoic acid than from 5,8,11,14‐eicosatetraenoic acid in the presence of antioxidants. Vitamin E suppressed the inhibitory effects of both PGE2 and palmitic acid on cell proliferation. The cyclic nucleotide phosphodiesterase inhibitors, caffeine and papaverine, suppressed the stimulatory effect of vitamin E on cell proliferation and enhanced the inhibitory effect of a triene acid on cell proliferation. Substrate and inhibitor specificities are consistent with the oxidative regulation of cell proliferation through the formation of hydroperoxy fatty acids. We propose that hydroperoxy fatty acids may regulate both cyclase and cyclic nucleotide phosphodiesterase enzymes through sulfhydryl‐disulfide interconversions. We suggest that this regulatory mechanism may help to explain the acculation of 5,8,11‐eicosatrienoic acid in essential fatty acid deficiency, the effects of antioxidants on cell proliferation, and one of the several effects of polyunsaturated fatty acids in proliferative disorders such as cancer and atherosclerosis.
The effect of isomerictrans‐18∶1 acids on the desaturation of palmitic, linoleic and eicosa‐8,11,14‐trienoic acids by rat liver microsomes
Authors: Mahfouz M. M. , Johnson S. , Holman R. T.
Published: November 2006

The inhibitory effects of the positional isomers oftrans‐18∶1 acids on the desaturation of palmitic acid to palmitoleic (Δ9‐desaturase), linoleic to γ‐linolenic (Δ6‐desaturase) and eicosa‐8,11,14‐trienoic to arachidonic acid (Δ5‐desaturase) were investigated. Thesetrans‐18∶1 acids were found to be inhibitory for the microsomal Δ6‐, Δ9‐ and Δ5‐desaturases of rat liver. The position of the double bond in thetrans‐18∶1 acids seems to be important in determining the degree of inhibition. At inhibitor/substrate ratio of 3∶1, the Δ6‐desaturase was most strongly inhibited bytrans‐Δ3,‐Δ4,‐Δ7 and‐Δ15‐18∶1 isomers, whereas the Δ9‐desaturase was most strongly inhibited bytrans‐Δ3,‐Δ5,‐Δ7,‐Δ10,‐Δ12,‐Δ13 and‐Δ16 isomers. At inhibitor/substrate ratio of 6∶1, the Δ5‐desaturase was most strongly inhibited by Δ3‐, Δ9‐, Δ13‐ and Δ15‐isomers. When 18∶0 was added to the incubations of 16∶0, 18∶2 and 20∶3 at the same I/S ratios used for thetrans‐18∶1 acids, weak inhibition for Δ9‐desaturase and no inhibition for Δ5‐and Δ6‐desaturases was observed.
Lipoprotein lipid and protein synthesis in experimental nephrosis and plasmapheresis. I: Studies in rat in vivo
Authors: Shafrir Eleazar , Brenner Talma
Published: November 2006

The incorporation of L‐4,5‐[3H]leucine into the ultracentrifugally separated apolipoproteins of very low, low, and high density lipoproteins (VLDL, LDL, HDL) and into serum albumin was found three‐to four‐fold higher in nephrotic than in normal rats one hour after intravenous injection. Incorporation of leucine into the circulating lipids was negligible. Increases of similar magnitude were obtained in the incorporation of simultaneously injected 1,5[14C] citrate into the lipids of VLDL, LDL, and HDL of nephrotic rats. Of the citrate carbons incorporated into serum and liver lipids, the proportion in cholesterol was higher in nephrotic rats when compared to normal rats. The incorporation of both precursors into total proteins and lipids of the liver vs. the incorporation into the lipoproteins was relatively lower in nephrotic than in control rats, indicating a preferential channeling into secretable products. The occurrence of enhanced new lipid synthesis in nephrosis was corroborated by the finding of markedly enhanced synthesis of lipoprotein‐borne fatty acids and cholesterol from3H2O. These results point out that while leucine is not an efficient in vivo precursor of lipoprotein lipids in nephrosis, de novo lipogenesis proceeds from other precursors. Similar trend of changes, though of smaller magnitude, was elicited in rats after double plasmapheresis, 18 hr apart, when measured 3 hr after the second plasma withdrawal. This indicates that the loss of circulating proteins either by direct removal or through kidney lesion stimulates the compensatory hepatic response involving excessive lipoprotein synthesis. Time‐course studies showed that peak incorporation of leucine and citrate into the protein and lipid components of lipoproteins, respectively, as well as into serum albumin, occurred coincidentally 3 hr after the second plasmapheresis, suggesting an interdependence of the enhanced protein and lipid synthesis.
Phospholipid metabolism inNeisseria gonorrhoeae: Phospholipid hydrolysis in nongrowing cells
Authors: Cacciapuoti Anthony F. , Wegener Warner S. , Morse Stephen A.
Published: November 2006

Hydrolysis of cell envelope phospholipids was demonstrated in cells of both autolytic and nonautolytic strains ofNeisseria gonorrhoeae that were labeled during growth in the presence of [3H] acetate. The label incorporated into the cellular phospholipids was located exclusively in the fatty acid acyl side chains. Labeled cells were incubated for 2 hr in N‐2‐hydroxyethylpiperazine‐N′‐2‐ethanesulfonic acid buffer, pH 8.5, containing various additions, and then examined for distribution of3H in lipids. Ca++ selectively stimulated the deacylation of phosphatidylethanolamine (PE), whereas Mn++ stimulated the deacylation of phosphatidylglycerol (PG). Hydrolysis of phosphatidylethanolamine by phospholipase A was accompanied by the accumulation of lysophosphatidylethanolamine (LPE) and free fatty acids in the cells. Free fatty acids accumulated to a greater extent than lysophosphatidylethanolamine, suggesting that the latter was further hydrolyzed to glycerophosphorylethanolamine (GPE) and free fatty acids by a lysophospholipase. Methanol, ethanol, propanol, and isopropanol, added at concentrations which inhibited growth by 50%, stimulated phospholipase A, but not lysophospholipase activity. Differences in heat inactivation, metal ion requirements, and pH optima suggested that phospholipase A activities with phosphatidylethanolamine or phosphatidylglycerol as substrate and lysophospholipase may be separate enzymes.
Thermal alteration of a cyclic fatty acid produced by a flaxseed extract
Authors: Vick Brady A. , Zimmerman Don C. , Weisleder David
Published: November 2006

Methyl 8‐[2‐(cis‐pent‐2′‐enyl)‐3‐oxo‐cis‐cyclopent‐4‐enyl] octanoate (I) is the methyl ester of a cyclic fatty acid synthesized enzymically from an incubation of linolenic acid with an extract of flaxseed (Linum usitatissimum L.). A proposed trivial name for I is methyl 12‐oxo‐cis‐10, 15‐phytodienoate (12‐oxo‐PDA). The evidence presented indicated that compound I has thecis configuration of the carbon chains with respect to the cyclopentenone ring. Treatment with acid, base, or heat isomerized I to a second product (II) that has thetrans configuration of the carbon chains. Prolonged heat treatment of II yielded a third cyclic product, methyl 12‐oxo‐9(13),cis‐15‐phytodienoate (III).
A specific spectrophotometric determination of long chain nitro compounds and its application to NO2‐initiated lipid autoxidation
Authors: Collard Randle S. , Pryor William A.
Published: November 2006

A specific spectrophotometric method is described for the determination of nitro‐β‐hydroperoxides produced during the initiation of lipid autoxidation by ppm NO2; this determination provides a measure of the rate of initiation by addition of NO2 to lipids. The nitro group is reduced to an amine using polymethylhydrosilane (PMHS) and Pd on charcoal, and the amine is then determined spectrophotometrically as a neutral methyl orange salt. Although this method was developed for the determination of micromolar quantities of nitro‐β‐hydroperoxides in lipid samples, it can be used to determine any long chain, nonpolar nitro compound. The method also can be adapted to allow the determination of polar or short chain nitro compounds by using a different amine determination.
Continuous spectrophotometric assay of conjugated bile acid hydrolase
Authors: Kirby Lyndon C. , Klein Robert A. , Coleman James P.
Published: November 2006

Conjugated bile acid hydrolase (CBAH) refers to a class of enzymes which catalyze the cleavage of the amino acid moieties from conjugated bile acids. These enzymes are significant because of their role in providing substrates for further microbial metabolism in the gastrointestinal tract. They also are used in research laboratories for the deconjugation of bile acids prior to structural analyses. A continuous spectrophotometric assay for CBAH activity was developed using a conjugate of cholic acid and the chromophore, 5‐amino‐2‐nitro‐benzoic acid. The free chromophore is detected by virtue of its absorbance at 410 nm. The CBAH fromClostridium perfringens displayed aKm for this substrate of 120 μM. These results demonstrate that this new compound functions as an effective substrate of the enzyme and forms the basis for a convenient and rapid method to monitor CBAH activity.
Use of gas chromatography/isotope ratio‐mass spectrometry to study triglyceride metabolism in humans
Authors: Binnert C. , Laville M. , Pachiaudi C. , Rigalleau V. , Beylot M.
Published: November 2006

The study of triglyceride (TG) metabolism using stable isotope tracers would be facilitated by being able to detect low13C enrichment. To meet this goal, we developed a gas chromatography/isotope ratio‐mass spectrometry technique to measure the enrichment of palmitate in nonesterified fatty acids (NEFA) and TG as its methyl derivative. This method allows accurate and reproducible measurements of enrichment as low as 0.009 mole percent excess (MPE), in a range between 0–0.65 MPE. The usefulness of this method is shown by two studies of lipid metabolism in human beings. First, we studied the metabolic fate of an oral TG load labeled with [1,1,1‐13C3]tripalmitin. Labeled palmitate appeared concurrently in plasma NEFA and TG, and four hours after the load, the labeling was higher in NEFA than in TG (MPE NEFA: 1.53±0.31 vs. MPE TG: 0.78±0.06,P<0.05). In a second study, the hepatic reesterification of NEFA was estimated by measuring the appearance of infused [1‐13C]palmitate in circulating TG. The estimated contribution of plasma NEFA to circulating TG increased to a maximum of 22%. Thus, gas chromatography/isotope ratio‐mass spectrometry appears to be a useful tool for future studies of lipid metabolism in humans.
Microscale synthesis of phosphatidyl‐[3H]choline from 1,2‐diacylglycerol. Assessment of isomerization by reversed‐phase high‐performance liquid chromatography
Authors: Bugaut Maurice , Gresti Joseph , Gagniarre Jerôme
Published: November 2006

The synthesis ofrac‐1‐palmitoyl‐2‐oleoylglycero‐3‐phospho‐[3H]choline of high specific activity was carried out on a microscale by making 7 μmol ofrac‐1‐palmitoyl‐2‐oleoylglycerol react first with an equimolar amount of POCl3 and then of [3H]choline. After purification by thin‐layer chromatography and normal‐phase high‐performance liquid chromatography (HPLC), the yield of the synthesis of [3H]phosphatidylcholine (120 μCi/μmol) was 22%.rac‐1‐Palmitoyl‐2‐oleoylglycerol was purified before use by reversed‐phase HPLC under conditions which were nonisomerizing and allowed the separation of 1,2‐ and 1,3‐isomers of diacylglycerol. Ethanol, but not benzene, was shown to cause isomerization of long‐chain diacylglycerol and, therefore, was not used for drying the substrate before reaction. A rapid and complete separation of 1,2‐ and 1,3‐isomers of long‐chain phosphatidylcholine was obtained by reversed‐phase HPLC using 20 mM choline chloride in methanol/acetonitrile/water (50∶50∶1, by vol) isocratically as the mobile phase. Under these conditions, analysis of the synthetizedrac‐1‐palmitoyl‐2‐oleoylglycero‐3‐phospho‐[3H]choline showed a total absence of 1,3‐isomer.
Lipid composition ofbacillus megaterium spores and spore membranes
Authors: Nikolopoulou M. , Vary J. C.
Published: November 2006

Bacillus megaterium QM B1551 spore lipids were extracted by an improved technique, and the phospholipid and fatty acid compositions were determined. Phospholipids accounted for 65% of the total fatty acids; the neutral lipid fraction contained 15% and the remaining fatty acids were in the interphase, aqueous phase and pellet from the lipid extraction. Each phospholipid had similar fatty acid compositions as did the delipidated pellet. However, the aqueous phase and, to some extent, the interphase had unique fatty acid compositions. Also, fatty acids were found acylated to proteins, which was observed by electrophoresis of delipidated proteins from spores grown in [1‐14C]palmitate. Therefore, spores contain unique non‐phosphatide fatty acid components that can now be analyzed.
Characterization of phospholipase A2 from rabbit lung microsomes
Authors: Filgueiras Octávio M. O. , Possmayer Fred
Published: November 2006

A phospholipase A2 activity associated with the microsomal fraction of rabbit lung homogenates was studied. The enzyme showed specificity for thesn−2 ester bond of phosphatidylcholine, had an alkaline pH optimum and required Ca2+ for activity. Other divalent cations were unable to support hydrolysis. In the absence of detergents, exogenous phosphatidylethanolamine was deacylated at a rate sevenfold higher than phosphatidylcholine. The activity toward both substrates could be enhanced by sodium deoxycholate or, more effectively, by sodium taurodeoxycholate. Phosphatidylethanolamine required higher detergent/phospholipid molar ratios than phosphatidylcholine. Under these conditions, the preference for the former substrate over the latter was nearly abolished. The zwitterionic detergent 3‐[(3‐cholamidopropyl) dimethylammonio]‐1‐propanesulfonate (CHAPS) and the nonionic detergent Triton X‐100 were either ineffective (phosphatidylcholine) or inhibitory (phosphatidylethanolamine). Addition of KCl produced opposite effects on the activity depending on the bile salt used to disperse the substrate. The phospholipase A2 activity was inhibited byp‐bromophenacyl bromide but remained unaffected after treatment with diisopropylfluorophosphate or NaF. N‐Ethylmaleimide, but not other thiol reagents, partially inhibited the activity.
New findings in the fatty acid composition of individual platelet phospholipids in man after dietary fish oil supplementation
Authors: Mori Trevor A. , Codde James P. , Vandongen Robert , Beilin Lawrence J.
Published: November 2006

Nine healthy male volunteers were given 15 Max EPA fish oil capsules providing 2.67 g of eicosapentaenoic acid (EPA, 20∶5ω3) and 1.72 g of docosahexaenoic acid (DHA, 22∶6ω3) daily for 3 wk. Measurements were taken at baseline, at the end of the fish‐oil period, and at 2 and 6 wk postsupplementation. The effect of fish oil on plasma lipids and the fatty acid composition of individual platelet phospholipids was studied. In general, the proportions of 20∶5ω3 and 22∶6ω3 in platelet phosphoglycerides were substantially increased mainly at the expense of arachidonic acid (AA, 20∶4ω6). A large and significant increase in the relative EPA content of phosphatidylcholine (PC) (P<0.001) and phosphatidylethanolamine (PE) (P<0.001) was noted at the end of the 3 wk supplementation. We have also shown for the first time a small but significant (P<0.001) incorporation of EPA in phosphatidylserine (PS). Incorporation of DHA was also detected in PC, PE and PS, whereas the relative AA content of these phospholipids was significantly reduced. Fish oil supplementation led to a significant increase of 22∶5ω3 in PS and decreases of 20∶3ω6 in PC and 22∶4ω6 in PE. Postsupplementation measurements showed a gradual return of all fatty acids to baseline levels. The fatty acid composition of the phosphatidylinositol (PI) fraction remained unchanged throughout the trial period. We conclude that in humans ω3 fatty acids are incorporated into platelet membrane phospholipid subclasses with a high degree of specificity.
Immunocytochemical localization of lingual lipase in serous cells of the developing rat tongue
Authors: Roberts Ingram M. , Nochomovitz Lucien E. , Jaffe Ronald , Hanel Selma I. , Rojas Magaly , Agostini R. A.
Published: November 2006

The ontogeny of the rat lingual serous and mucous glands was explored by light and electron immune microscopy using the peroxidase‐antiperoxidase and streptavidin‐gold techniques. Tissues from fetal and neonatal rats from day 18 of gestation through 4 wk after birth were fixed and embedded in paraffin or Epon for light and transmission electron microscopy, respectively. Electron microscopy revealed that the only cells containing lingual lipase were the developing serous cells; secretory granules containing lingual lipase of varying degrees of maturity were seen. Mucous cells did not show immunospecific staining in rats of any age. The neonatal “mixed” lingual glands secrete lingual lipase from serous components immediately after birth to aid in fat digestion.
Mass spectra of the picolinyl esters of isomeric mono‐ and dienoic fatty acids
Authors: Christie W. W. , Brechany E. Y. , Holman R. T.
Published: November 2006

The picolinyl ester derivatives of the complete series of isomeric octadecenoates, methylene‐interrupted octadecadienoates, and of octadec‐9‐ynoate have been subjected to gas chromatography‐mass spectrometry. A fused‐silica capillary column, coated with a cross‐linked methyl silicone, was used for the separation. Electron impact spectra were determined at 70 eV. Earlier observations with a limited series of model compounds were confirmed, and it was shown that the picolinyl ester derivatives were of almost universal value in the location of double bonds in such isomers. Difficulties of interpretation arose mainly when the double bonds were close to the carboxyl group.
Characterization of feline omentum lipids
Authors: McCluer Robert H. , Evans James E. , Williams Marcia , Griffith Ann L. , Catsimpoolas Nicholas
Published: November 2006

Feline omental lipid extracts, previously reported to be angiogenic in the cornea of rabbits, were fractionated and the major lipid components characterized. Approximately 97% of the chloroform/methanol extract consisted of triglycerides containing primarily 16∶0, 18∶0, 18∶1 and 18∶2 fatty acids. Trace quantities of free fatty acids, cholesterol, di‐ and monoglycerides were also detected. The phospholipid fraction, obtained by solvent partition and Unisil column chromatography and characterized by high performance liquid chromatography (HPLC)‐mass spectrometry, was found to consist of phosphatidylcholine, sphingomyelin, phosphatidylethanolamine and phosphatidylserine. The neutral glycolipids, isolated by solvent partition and Unisil column chromatography and identified by high performance thin layer chromatography and HPLC of their perbenzoylated derivatives, were found to consist of glucosyl‐ and galactosylceramides, galabiosylceramide, lactosylceramide, globotriaosylceramide and globotetraosylceramide. The complex glycolipid fraction, obtained from Folch upper phase solvent partition, was found to consist primarily of Forssman glycolipid and gangliosides GM3 and GD3. Smaller amounts of GM1 and other unidentified gangliosides were also present.
Influence of environmental medium on fatty acid composition of human cells: Leukocytes and fibroblasts
Authors: Delplanque B. , Jacotot B.
Published: November 2006

Fibroblasts in culture and leukocytes have been widely used to study fatty acid and lipoprotein cellular metabolism. The present investigations were designed to study the role of nutritional and environmental factors on lipid metabolism in these two types of cells. Leukocytes freshly isolated from human blood and fibroblasts cultured in media enriched in human serum (HS) have relatively similar fatty acid distributions. However, more important differences are observed in fibroblasts cultured in media enriched with HS or with fetal bovine serum (FBS). It is obvious that the quantity and quality of fatty acids are very different in FBS and HS, but intracellular regulation ensures relative homogeneity of saturated (SFA) and monounsaturated fatty acids (MUFA) in the cells, particularly in phospholipids.

The first modifications induced by different media (FBS or HS) are detected on cellular growth; the differences seem to be due more to the fatty acid (FA) quantitative supply than to the FA quality of each culture medium. The major modifications in FA composition induced by different culture media concern the polyunsaturated fatty acids (PUFA) of phospholipids, especially the n−6 family. The intracellular linoleic acid level depends on the level in the medium, but intracellular n−6 metabolite levels depend both on the level in the medium and on the growth state of the cells. The n−3 family seems to be less affected by the quality of the medium in our experiment, and the cells maintain a stable docosahexaenoic acid (22∶6n−3) level. A higher content of the n−3 family in the medium induces a higher level of eicosa‐or docosapentaenoic acid, rather than docosahexaenoic acid itself.

Finally, the FA quality of the medium influences the cellular PUFA content but, with a low FA quantitative supply, the FA quality of the medium has less influence on the cellular PUFA quality, and apparently has no effect on the SFA content of phospholipids. Modification of the quantitative supply of the medium and of the quality of the cells (strain and growing state) are more important for the distribution of SFA and MUFA in the neutral lipids of the cells.
1‐Acyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine from stimulated human polymorphonuclear leukocytes
Authors: Satouchi Kiyoshi , Oda Makoto , Saito Kunihiko
Published: November 2006

1‐Acyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine (1‐acyl‐2‐acetyl GPC) was found in the fraction of platelet‐activating factor obtained from stimulated human polymorphonuclear leukocytes (PMN). The amount of 1‐acyl‐2‐acetyl GPC obtained from 1×107 PMN stimulated with ionophore A23187 at 37 C for 15 min ranged from 8 to 56 pmol (32±10 pmol, mean±standard error; n=4). The main species was 16∶0 palmitoyl (17±5 pmol), followed by 18∶0 stearoyl (8±3 pmol) and 18∶1 oleoyl (7±3 pmol).

Although the physiological significance is unknown, 1‐acyl‐2‐acetyl GPC was always detected when 1‐alkyl‐2‐acetyl GPC was detected.
Rapid analysis of jojoba wax fatty acids and alcohols after derivatization using Grignard reagents
Authors: Pina M. , Pioch D. , Graille J.
Published: November 2006

This method, based on the action of Grignard reagents, is an original approach to wax derivatization and differs from the methods previously described, which were essentially based on wax alcoholysis. Grignard reagents, especially magnesium ethyl bromide, react on ester functions to turn the wax constituents into primary and tertiary alcohols, the latter being the fatty acid derivatives. The mixture of these alcohols is analyzed by a single gas chromatographic injection. The overall time, about 1.5 hr, makes this method suitable for routine analysis. It could be also considered for analyzing low carbon condensation organic acid esters.
Biosynthesis of hydrocarbons by algae: Decarboxylation of stearic acid to N‐heptadecane inAnacystis nidulans determined by13C‐ and2H‐labeling and13C nuclear magnetic resonance
Authors: McInnes A. Gavin , Walter John A. , Wright Jeffrey L. C.
Published: November 2006

The distribution of isotopic labels inn‐heptadecane enriched from [1,2‐13C] and [2‐13C, 2‐2H3) acetates byAnacystis nidulans has been determined by13C nuclear magnetic resonance (13C NMR). Labeling with [1,2‐13C] acetate is consistent with assembly from13C−13C units derived from an acetate “starter” group and 8 malonate units, as in fatty acid biosynthesis, followed by production of a methyl group through bond cleavage of the terminal13C−13C unit. A comparison of the hydrocarbon with palmitic acid (the only fatty acid produced in sufficient amount for NMR analysis) enriched from [2‐13C,2‐2H3]acetate by the same culture shows that they have retained the same fraction of2H at corresponding sites, and have therefore undergone identical biosynthetic and hydrogen‐deuterium exchange processes, as would be expected ifn‐heptadecane originates from de novo‐synthesized stearic acid.