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PubMed1990

Priming of the respiratory burst in human eosinophils is accompanied by changes in signal transduction.

Addition of platelet-activating factor (PAF) to human eosinophils leads to the modulation of eosinophil responses. The respiratory burst, induced by opsonized particles, consists of an initiation and a propagation phase and is greatly enhanced ("primed") after pretreatment with PAF. This priming event induces the following changes in signal transduction between the opsonin receptors (in particular the CR3 receptor) and activation of the respiratory burst: 1) an enhanced activation of protein kinase C (PK-C): the initiation of the respiratory burst in untreated eosinophils is not sensitive to PK-C inhibition (via staurosporine) and is not accompanied by accumulation of diglycerides and changes in [Ca2+]i. After pretreatment with PAF, the initiation of the response is partly sensitive to inhibition of PK-C (via staurosporine) and is accompanied by accumulation of diglycerides and a fast and sustained increase in [Ca2+]i; and 2) an enhancement of a PK-C-independent initiation of the respiratory burst. The propagation phase in both primed and unprimed cells is sensitive for inhibition by staurosporine. Our results indicate that in eosinophils the phospholipase(s) responsible for the accumulation of the diglycerides and changes in [Ca2+]i during the initiation phase of the serum-treated zymosan response seem(s) to become associated with the signal transduction route only after priming with PAF. This results in the occurrence of two signal transduction routes that can act independently of each other.

Alkaloids↗
PubMed1988

Phospholipase A2 activation in human neutrophils. Differential actions of diacylglycerols and alkylacylglycerols in priming cells for stimulation by N-formyl-Met-Leu-Phe.

Both 1,2-diacyl- and 1-O-alkyl-2-acylglycerols are formed during stimulation of human neutrophils (PMN), and both can prime respiratory burst responses for stimulation by the chemotactic peptide, N-formyl-Met-Leu-Phe (fMLP); however, mechanisms of priming are unknown. Arachidonic acid (AA) release through phospholipase A2 activation and metabolism by 5-lipoxygenase are important activities of PMN during inflammation and could be involved in the process of primed stimulation. Therefore, we have examined the ability of diacyl- and alkylacylglycerols to act as priming agents for AA release and metabolism in human neutrophils. After prelabeling PMN phospholipids with [3H]AA, priming was tested by incubating human PMN with the diacylglycerol, 1-oleoyl-2-acetylglycerol (OAG), or its alkylacyl analog, 1-O-delta 9-octadecenyl-2-acetylglycerol (EAG) before stimulating with fMLP. fMLP (1 microM), OAG (20 microM), or EAG (20 microM) individually caused little or no release of labeled AA. However, after priming PMN with the same concentrations of either OAG or EAG, stimulation with 1 microM fMLP caused rapid (peak after 1 min) release of 6-8% of [3H]AA from cellular phospholipids; total release was similar with either diglyceride. Priming cells with OAG also enhanced conversion of released AA to leukotriene B4 (LTB4) and 5-hydroxyeicosatetraenoic acid (5-HETE) upon subsequent fMLP stimulation, but AA metabolites were not increased in EAG-primed PMN. If fMLP was replaced with the calcium ionophore A23187 (which directly causes release of AA and production of LTB4 and 5-HETE), priming by both diglycerides again enhanced release of [3H]AA, but only OAG priming increased lipoxygenase activity. Indeed, EAG pretreatment markedly reduced LTB4 and 5-HETE production. Thus, both diglycerides prime release of AA from membrane phospholipids but have opposite actions on the subsequent metabolism of AA.

Arachidonic Acid↗
PubMed1978

CTP-phosphatidic acid cytidyltransferase from Saccharomyces cerevisiae. Partial purification, characterization, and kinetic behavior.

CTP-phosphatidic acid cytidyltransferase catalyzes the formation of CDP-diglyceride from CTP and phosphatidic acid. The enzyme was solubilized from crude mitochondrial membrane by treatment with digitonin and was further purified by chromatography on DEAE-Sephadex, quaternary aminoethyl (QAE) Sephadex, and Sepharose 6B columns. At this stage the enzyme, enriched 550-fold over crude cell homogenate, still remains associated with phospholipid and has an estimated approximate molecular weight of 400,000 on the basis of gel filtration chromatography. Sodium dodecyl sulfate polyacrylamide gel electrophoresis of the 550-fold enriched enzyme yielded two major protein bands having molecular weights of 45,000 and 19,000. The enzyme exhibits an absolute dependence on Triton X-100, a sharp Mg2+ dependence with an optimum at 20 mM, and a pH optimum of 6.5 for activity. The product of the CTP-phosphatidic acid cytidyl-transferase reaction has been isolated and identified as CDP-diglyceride, both for the crude enzyme preparation as well as for the 550-fold enriched enzyme. CTP-phosphatidic acid cytidyltransferase is capable of catalyzing the reverse reaction in the presence of pyrophosphate, utilizing CDP-diglyceride as substrate. The product of the reverse reaction was identified as CTP. Kinetic analysis of the behavior of CTP-phosphatidic acid cytidyltransferase was performed at three different stages of its purification. Initial analysis of the data yielded biphasic behavior in double reciprocal plots with respect to both substrates. Hill plots of the data indicated the presence of negative cooperativity. A detailed analysis of the kinetic behavior was performed on the enzyme purified 550-fold. The data suggest a mechanism involving two distinct cycles of catalysis, responsive to homotropic modification, with different affinities for both substrates. Further analysis of the kinetic behavior in the presence of inhibitors (dCTP and PPi) yielded a reaction order for the entrance of substrates and departure of products from the reaction cycles. The high affinity site catalyzes the reaction via a double displacement mechanism and is the predominant form at low concentrations of substrates. At high concentrations of substrates the low affinity site starts contributing significantly to the reaction velocity with an ordered single displacement mechanism. In each case CTP is the first substrate to attach and PPi is the first product released.

Cytidine Diphosphate Diglycerides↗
PubMed1980

An improved procedure for the synthesis of 14C-labeled phosphatidylserine from cerebral phosphatidic acid.

A complete procedure to prepare a highly labeled phosphatidyl-L-[U-14C]serine possessing the same fatty acid composition of brain phospholipids is reported. CDP-diglyceride was synthesized by reaction between phosphatidic acid and CMP-morpholidate as the dicyclohexylcarboxamidium salt. The reaction between CDP-diglyceride and L-[U-14C]serine to produce the labeled phosphatidylserine was catalyzed by the CDP-diglyceride: L-serine phosphatidyl transferase (EC 2.7.8.8) from E. coli. A selective inhibition of phosphatidylserine decarboxylase activity, present as contaminant in the enzyme extract, was introduced in order to avoid a low yield of product. Traces of phosphatidylethanolamine (about 1%) were easily removed by preparative thin-layer chromatography. The yield of the labeled product was as high as 87% and it specific radioactivity was 170 mCi/mmol.

Animals↗
PubMed1983

Ca2+.Calmodulin-dependent release of arachidonic acid for renal medullary prostaglandin synthesis. Evidence for involvement of phospholipases A2 and C.

The present study examined (a) the source of arachidonic acid for Ca2+-stimulated renal inner medullary prostaglandin synthesis, (b) the Ca2+-dependence of enzymes of the phospholipase A2 and C pathways, and (c) the role of calmodulin in these Ca2+ actions. Ca2+ plus the ionophore A23187 stimulated (2-4-fold) release of labeled arachidonate, diglyceride, prostaglandin E2 or F2 alpha from inner medullary slices with a concomitant fall in labeled phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine. The calmodulin antagonist N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide hydrochloride (W-7) (10-100 microM) abolished or suppressed Ca++-stimulated immunoreactive prostaglandin E, labeled arachidonate and prostaglandin release, and the fall in labeled phospholipids but did not suppress labeled diglyceride or inositol accumulation. Studies in subcellular fractions demonstrated a particulate phospholipase A2 activity and a phosphatidylinositol-specific phospholipase C activity which was predominantly soluble (80%). W-7 or trifluoperazine (25 microM) abolished Ca2+-stimulated phospholipase A2 activity and particulate phospholipase C activity but were without effect on soluble phospholipase C. W-7 (100 microM) was without effect on Ca2+-stimulated diglyceride lipase and phosphatidic acid-specific phospholipase A2 activities. Hypertonic urea at concentrations that pertain in the inner medulla of hydropenic rats in vivo inhibited Ca2+-induced increases in labeled arachidonate release and immunoreactive prostaglandin E in slice incubates and Ca2+-responsive phospholipase C and A2. The results are consistent with the involvement of phospholipase A2, C, or both in the Ca2+ (+A23187)-stimulated release of free arachidonate for prostaglandin synthesis and support a role for calmodulin in Ca2+ activation of phospholipase A2 and particulate phospholipase C.

Animals↗
PubMed1996

Sustained activation of phospholipase D via adenosine A3 receptors is associated with enhancement of antigen- and Ca(2+)-ionophore-induced secretion in a rat mast cell line.

The adenosine analog, N-ethylcarboxamidoadenosine (NECA), causes transient activation of phospholipase C and an enhancement of antigen-induced secretion in a rat mast cell (RBL-2H3) line via adenosine A3-receptors (Ramkumar et al., J. Biol. Chem. 268:16887, 1993) by a mechanism that is inhibited by bacterial toxins and potentiated by dexamethasone (Ali et al., J. Biol. Chem. 265:745-753, 1990). Here we show that NECA synergizes the secretory response to Ca(2+)-ionophore as well as to antigen. The ability of NECA to synergize the secretory responses persisted for 10 to 20 min, long after the early phospholipase C-mediated reactions to NECA had subsided. NECA caused, however, a dose-dependent sustained activation of phospholipase D, as indicated by the formation of [3H]phosphatidic acid, or in the presence of 0.3% ethanol, [3H]phosphatidylethanol. This activation was associated with a sustained increase in diglycerides, in protein kinase C activity and in the phosphorylation of myosin light chains by protein kinase C. The generation of diglycerides was enhanced in dexamethasone-treated cells and suppressed in cells that had been treated with cholera toxin or pertussis toxin. Collectively, the studies suggested that the generation of diglycerides via phospholipase D and the associated activation of protein kinase C were, by themselves, insufficient signals for secretion in RBL-2H3 cells, but that these reactions synergized responses to stimulants such as antigen or A23187 that caused substantial increases in [Ca2+]i.

Adenosine↗
PubMed1988

[3H]arachidonic acid metabolism in rat brain minces: effects of nucleotide triphosphates, CDPcholine and CMP.

Rat brain minces were used to investigate the effects of nucleotides on the metabolism of arachidonic acid in nerve tissue. Brain free fatty acids, neutral lipids and phospholipids, were radiolabeled in vivo following intracerebral injection of [3H]arachidonic acid. Minces were prepared from the radiolabeled cerebra and were incubated in a modified Krebs-Ringer buffer with and without various nucleotides. The incubation-induced accumulation of unesterified [3H]arachidonate was reduced in the presence of CDPcholine, ATP, CTP, GTP, and UTP. These nucleotides inhibited choline and inositol glycerophospholipid hydrolysis. They also reduced the amount of labeled diglycerides. However, CDPethanolamine had no effect on arachidonic acid metabolism in the mince preparation and CMP appeared to stimulate further hydrolysis of choline glycerophopholipids, resulting in increased accumulation of [3H]arachidonic acid and labeled diglycerides. We suggest that the production of unesterified [3H]arachidonate and labeled diglycerides is due to the involvement of more than one catabolic reaction, since the high energy nucleotides had similar effects on fatty acid accumulation, but different effects on phospholipid labeling.

Animals↗
PubMed1975

Hepatoma, host liver, and normal rat liver phospholipids as affected by diet.

Individual phospholipid classes derived from hepatoma, host liver, and normal liver of rats maintained on chow and fat free diets were examined in detail and the sphingomyelin and phosphoglyceride structures compared. The concentration of hepatoma spingomyelin was higher while phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and diphosphatidylglycerol were only one-fourth to one-half normal liver concentrations, irrespective of diet. Hepatoma phosphatidylcholine, phosphatidylethanolamine, phosphatidyl-serine, and phosphatidylinositol contained higher percentages of 18:1 and, except phosphatidylinositol, much lower percentages of most polyunsaturated fatty acids than liver. The 1-position of host liver phosphatidylcholine and phosphatidylethanolamine, normal liver phosphatidylcholine and phosphatidylethanolamine, and hepatoma phosphatidylcholine from animals on both diets had the same approximate fatty acid composition, but the percentage of 16:0 in hepatoma phosphatidylethanolamine was reduced dramatically. The low percentage of 16:0 at the 1-position of both phosphatidylethanolamine and triglycerides suggests that the 1-position fatty acids of these two classes may have a similar origin. The fat free diet reduced the percentage of 18:2 in liver diphosphatidylglycerol 3-fold and the decrease was offset by increased percentages of 16:1 and 18:1; whereas the very low percentage of 18:2 in hepatoma diphosphatidylglycerol was offset by increased percentages of 18:0 and 16:0. Liver phosphatidylinositol and phosphatidylcholine from the animals fed the fat free diet contained the highest percentage of 20:3, which replaced 20:4. Hepatoma sphingomyelin contained a much higher concentration of 24:0 and 24:1 than liver. The hepatoma sphingomyelin also contained a C-24 dienoic acid, which was not detected in host and normal liver. Host liver contained a higher percentage of 22:6 than normal liver. The diglycerides derived from host liver PC contained a significantly higher percentage of carbon number 38 than normal liver. Diglycerides derived from hepatoma phosphatidylcholine and phosphatidylethanolamine exhibited a 1-random-2-random distribution of fatty acids, whereas diglycerides from liver phosphatidylcholine and phosphatidylethanolamine showed pairing of specific fatty acids.

Animals↗
PubMed1975

Effect of acute dietary alteration upon intestinal lipid synthesis.

The specific activities of three enzymes engaged in complex lipid synthesis, diglyceride acyltransferase, cholinephosphotransferase, and lysolecithin acyltransferase were studied in intestinal mucosa of hamsters fed either saline, hydrolyzed casein, or corn oil for 9 1/2 hr. In the most proximal intestine, saline feeding was associated with a reduced specific activity in villous tips with all three enzymes studied when compared with the two caloric supplemented groups. In the most distal intestine, oil feeding increased the activity of lysolecithin acyltransferase and choline phosphotransferase twofold as compared to casein fed hamsters; diglyceride acyltransferase was increased one- and one-half-fold. The response of lysolecithin acyltransferase and diglyceride acyltransferase to fat feeding was incomplete when compared to hamsters fed a fat supplemented diet for 7 days, suggesting that their pattern of response to dietary substrate was similar to the disaccharidases. By contrast, the response of cholinephosphotransferase to fat feeding was complete at 24 hr, suggesting that it responds in a manner similar to the glycolytic enzymes.

Acyltransferases↗
PubMed1988

Separation of neutral lipid, free fatty acid and phospholipid classes by normal phase HPLC.

Normal phase high performance liquid chromatography methods are described for the separation of neutral lipid, fatty acid and five phospholipid classes using spectrophotometric detection at 206 nm. Separations were accomplished in less than 10 min for each lipid class. A mobile phase consisting of hexane/methyltertiarybutylether/acetic acid (100:5:0.02) proved effective in separating cholesteryl ester and triglyceride with recoveries of 100% for radiolabeled cholesteryl oleate and 98% for radiolabeled triolein. Free fatty acid and cholesterol were separated by two different mobile phases. The first, hexane/methyltertiarybutylether/acetic acid (70:30:0.02) effectively separated free fatty acids and cholesterol, but did not separate cholesterol from 1,2-diglyceride. A mobile phase consisting of hexane/isopropanol/acetic acid (100:2:0.02) effectively separated free fatty acid, cholesterol, 1,2-diglyceride and 1,3-diglyceride. Recoveries of oleic acid and cholesterol were 100% and 97%, respectively. Five phospholipid classes were separated using methyltertiarybutylether/methanol/aqueous ammonium acetate (pH 8.6) (5:8:2) as the mobile phase. The recoveries of phosphatidylinositol, phosphatidylethanolamine, phosphatidylcholine, sphingomyelin and lysophosphatidylcholine were each greater than 96%.

Animals↗
PubMed2006

Human adipose triglyceride lipase (PNPLA2) is not regulated by obesity and exhibits low in vitro triglyceride hydrolase activity.

AIMS/HYPOTHESIS: The recent identification of murine adipose triglyceride lipase (ATGL, now known as patatin-like phospholipase domain containing 2 [PNPLA2]), gene product of Pnpla2, has questioned the unique role of hormone sensitive lipase (HSL, now known as LIPE), gene product of Lipe, in fat cell lipolysis. Here, we investigated human ATGL and HSL adipose tissue gene expression and in vitro lipase activity. SUBJECTS, MATERIALS AND METHODS: Levels of mRNA in adipose tissue from healthy obese and non-obese subjects were measured and lipase activity and adipocyte lipolytic capacity determined. HSL and ATGL cDNAs were transfected into Cos-7 cells and the relative tri- and diglyceride hydrolase activities were measured. RESULTS: Obesity was associated with a decreased subcutaneous and increased omental adipose tissue level of HSL mRNA. Subcutaneous HSL mRNA content was normalised upon weight reduction. In contrast, ATGL mRNA levels were unaffected by obesity and weight reduction. A high adipose tissue lipase activity was associated with increased maximal lipolysis and increased HSL, but not with ATGL mRNA levels. The in vitro triglyceride hydrolase activity of HSL was markedly higher than that of ATGL and contrary to HSL, ATGL was devoid of diglyceride hydrolase activity. The use of a selective HSL-inhibitor resulted in complete inhibition of HSL-mediated tri- and diglyceride hydrolase activity. The pH profile of human white adipose tissue triolein hydrolase activity was identical to that of HSL but differed from the ATGL profile. CONCLUSIONS/INTERPRETATION: HSL, but not ATGL gene expression shows a regulation according to obesity status and is associated with increased adipose tissue lipase activity. Moreover, HSL has a higher capacity than ATGL to hydrolyse triglycerides in vitro.

Adult↗
PubMed1983

Characterization of rat kidney proximal tubule brush border membrane-associated phosphatidylinositol phosphodiesterase.

Isolated rat kidney proximal tubule brush border membrane vesicles exhibit an increase in diacylglycerol levels (20- to 30-fold) and a concomitant decrease in phosphatidylinositol when incubated with [3H]arachidonate-labeled lipids, Ca2+, and deoxycholate. Levels of free arachidonate, triglyceride, and noninositol phospholipids are not altered. These results suggest phosphatidylinositol phosphodiesterase activity is associated with rat proximal tubule brush border membrane. Presence of both deoxycholate and certain divalent cations was necessary to demonstrate enzyme activity. Optimum pH ranged from 7.0 to 8.5. Ca2+, Mg2+, and Mn2+ stimulated diglyceride production while Ba2+, Zn2+, Hg2+, and K+ were ineffective. HgCl2 inhibited Ca2+-stimulated phosphatidylinositol phosphodiesterase. Mg2+ and deoxycholate-dependent enzyme activity was shown to be phosphatidylinositol specific. Sodium lauryl sulfate, tetradecyltrimethylammonium bromide, and Triton X-100 did not activate phosphatidylinositol phosphodiesterase in the presence of Ca2+. In combination with deoxycholate, diglyceride formation was not affected by sodium lauryl sulfate, partially inhibited by Triton X-100, and completely abolished by tetradecyltrimethylammonium bromide. Diglyceride kinase activity was not found associated with brush border membrane phosphatidylinositol phosphodiesterase. ATP (1-5 mM) inhibited Ca2+- or Mg2+-stimulated, deoxycholate-dependent phosphatidylinositol hydrolysis by chelating the required divalent cation.

Adenosine Triphosphate↗
PubMed1978

Identification of the sulfolipids in the non-photosynthetic diatom Nitzschia alba.

The four major sulfolipids in the non-photosynthetic marine diatom, Nitzschia alba, were isolated in pure form and their structures were established spectrometrically and by identification of their hydrolysis products as (a) 24-methylene cholesterol sulfate, (b) 1-deoxyceramide-1-sulfonate, (c) phosphatidyl sulfocholine (a sulfonium analogue of phosphatidylcholine) and (d) sulfoquinovosyl diglyceride. The major characteristic fatty acids of the sulfolipids were: for the deoxyceramide sulfonate, 16 : 0 (26%) and 16 : 1-delta3-trans (64%); for the sulfonium analogue, 14 : 0 (30%), 18 : 1 (12%), 18 : 2 (8%), 20 : 5 (27%) and 22 : 6 (4%); and for the sulfoquinovosyl diglyceride (two species, respectively), 14 : 0 (9%, 22%), 16 : 0 (16%, 28%), 18 : 1 (8%, 22%), 20 : 5 (42%, 23%) and 22 : 6 (14%, 2%). Traces of lyso-derivatives of sulfoquinovosyl diglyceride and phosphatidyl sulfocholine were also detected. The deoxyceramide sulfonate and the phosphatidyl sulfocholine represent novel membrane lipid components not previously detected in other organisms. They may however have a widespread distribution in marine diatoms and perhaps in marine organisms generally.

Ceramides↗
PubMed1975

Lipids in plant tissue cultures. IV. The characteristic patterns of lipid classes in callus cultures and suspension cultures.

Lipids from callus cultures and suspension cultures of higher plants constitute 5 to 8% of the dry tissue's weight. The predominant lipid classes are the sterols, steryl esters, steryl glycosides and esterified steryl glycosides. Considerable amounts of a variety of sterylglycolipids, whose structures are not completely elucidated, are also present. Triglycerides and phospholipids occur in small proportions, whereas monogalactosyl diglycerides, digalactosyl diglycerides and sulfoquinovosyl diglycerides are present only in traces, if at all. Beta-Sitosterol is the predominant constituent sterol, stigmasterol and campesterol as well as a variety of as yet unidentified sterols occur in smaller proportions. The major constituent fatty acids are palmitic, oleic, linoleic and linolenic acids. Saturated very long-chain fatty acids are found in smaller proportions. Unusual fatty acids, such as epoxy acids, which occur in the seed lipids of certain plants, are not found in tissue cultures derived from these plants. Clucose and traces of galactose are the only sugars obtained by acid hydrolysis of the glycolipids occurring in plant tissue cultures.

Cell Division↗
PubMed1978

The fatty acid composition of various lipid fractions isolated from erythrocytes and blood plasma of patients with Duchenne and congenital myotonic muscular dystrophy.

Ten lipid fractions, both neutral and phospholipids, were isolateed from erythrocytes of patients with Duchenne and congenital myotonic dystrophy. These fractions were: phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, sphingomyelin, lysophosphatidylcholine, phosphatidic acid, glycosphingolipids, triglycerides, diglycerides and one unknown. The fatty acid compositions were compared with control values. The major deviation was a decreased level of palmitoleic acid (16 : 1omega7) in three neutral lipid fractions. It was lowered from 9.1 to 1.3% in diglycerides and from 10.6 to 2.6% in triglycerides in myotonic dystrophy. In Duchenne muscular dystrophy this percentage was decreased from 9.1 to 4.0 in diglycerides. From blood plasma were isolated phosphatidylcholine, lysophosphatidylcholine, sphingomyelin and phosphatidylethanolamine. The myristic acid (14 : 0) content was raised in lysophosphatidylcholine (from 4.4 to 8.6%) and in sphingomyelin (from 3.3 to 5.0%) in myotonic dystrophy, In the latter phospholipid the stearic acid level was decreased from 18.6 to 12.8%. In phosphatidylcholine from plasma in myotonic dystrophy the level of eicosatrienoic acid (20 : 3omega6) was lowered from 3.1 to 2.0%. Plasma fractions from Duchenne dystrophy showed no deviation. The results do not constitute an explanation for the various biochemical abnormalities found in dystrophic erythrocytes. Neither do they point to a defect in a major pathway in lipid metabolism. However, an aberration in the de novo synthesis of lipids in immature red blood cells cannot be excluded.

Adolescent↗
PubMed1983

Effect of chlorpromazine on lipid metabolism in aortas from cholesterol-fed rabbits and normal rats, in vitro: inhibition of sterol esterification and modification of phospholipid synthesis.

Chlorpromazine (CPZ), a major tranquilizer, was found to be a potent inhibitor of acylCoA:cholesterol acyltransferase (ACAT, EC 2.3.1.26) in isolated arterial microsomes and in intact arterial tissue from the rat and cholesterol-fed rabbit in vitro. In isolated rabbit arterial microsomes, CPZ resulted in a concentration-dependent inhibition of ACAT with 50% inhibition of [1-14C]oleoylCoA incorporation into [14C]cholesteryl esters occurring at 0.1 mM CPZ. CPZ also effectively inhibited the incorporation of [14C]oleate into triglycerides without affecting incorporation into diglycerides. Additionally, CPZ altered the pattern of arterial phospholipids synthesized from [1-14C]oleate. Incorporation into phosphatidylcholine was depressed while incorporation into phosphatidylinositol was increased. Since diglyceride synthesis appeared to be unaffected by CPZ, a redirection of phosphatidic acid into the CDP-diglyceride pathway of glycerolipid synthesis does not adequately account for the effect of CPZ on arterial phospholipid and triglyceride synthesis in these experiments.

Animals↗
PubMed1969

Ueber die galactolipide und fettsäuren in normalen und glucosestimulierten kulturen von Spirodela oligorrhiza.

The levels of galactosyl diglycerides and the composition of fatty acids of Spirodela oligorrhiza (Lemnaceae) plants cultivated on a nutrient containing 1% glucose were studied. Controls were grown on a medium without glucose. Between the 10(th) and the 25(th) day of growth the ether-soluble lipids of glucose-stimulated plants contained less monogalactosyl diglyceride (MG) but more digalactosyl diglyceride (DG) than controls. In the same time a marked decrease of the relative amount of C(18:3) acid and an increase of that of C(18:2) and C(16:0) acids was observed. These changes of the lipid composition might be one reason for the structural changes in the chloroplast fine structure of glucose-stimulated Spirodela plants.

Journal Article↗
PubMed1994

Determination of neutral lipids from subcutaneous fat of cured ham by capillary gas chromatography and liquid chromatography.

The determination of neutral lipids in fat of cured ham is reported. Fat samples were extracted with chloroform-methanol (2:1) and neutral lipids and free fatty acids were separated on an aminopropyl minicolumn, the first fraction with chloroform-2-propanol (neutral lipids) and the second fraction with 2% acetic acid in diethyl ether (free fatty acids). Neutral lipids were fractionated with minicolumns, with aminopropyl and silica stationary phases. Two fractions were obtained with the first column: (A) triglyceride and cholesteryl esters and (B) cholesterol and mono- and diglycerides. Fraction A was applied to the silica column to obtain two new fractions: (C) cholesteryl esters and (D) triglycerides. Fractions B and C were analysed by capillary gas chromatography (cGC) and fraction D by cGC and HPLC. The R.S.D.s obtained were below 5% except for the monoglycerides (8%). Cholesteryl esters were determined by cGC in 5 min with R.S.D. 5%. The main triglycerides identified were PPO, POS, POO, POL and OOO (P = palmitic acid, O = oleic acid, L = linoleic acid; S = stearic). Monoglyceride and diglycerides having 18, 34 and 36 carbon atoms were the most abundant. The determination of triglycerides by HPLC was more difficult than by cGC because the linearity with HPLC was concentration dependent. The procedure allowed the determination of neutral lipid classes without derivatization of mono- and diglycerides.

Adipose Tissue↗