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PubMed1979

Cellular lipids of the Legionnaires' disease bacterium.

We qualitatively and quantitatively analyzed the simple and complex lipids of 10 Legionnaires' disease bacteria. The phospholipids in decreasing order of concentration were phosphatidylcholine, phosphatidylethanolamine, cardiolipin, phosphatidylmonomethylethanolamine, phosphatidylglycerol, and phosphatidyldimethylethanolamine. The total phospholipids averaged 96 micromoles per gram dry cell weight. Phospholipid fatty acids were solely branched-chain fatty acids and were, in decreasing order of concentration, iso-C16:0, anteiso-C15:0, anteiso-C17:0, iso-C14:0, iso-C16:1, and an unidentified fatty acid. Neutral lipids identified were free fatty acid, ubiquinone, triglyceride, diglyceride, monoglyceride, and wax ester. Neutral lipid fatty acids consisted predominately of branched-chain fatty acids, normal fatty acids, and a minor unidentified fatty acid. Analysis of the cellular lipids of 10 Legionnaires' disease bacteria revealed an unusual and novel microorganism.

Bacteria↗
PubMed1999

Apolipoprotein A-I charge and conformation regulate the clearance of reconstituted high density lipoprotein in vivo.

While low apolipoprotein A-I (apoA-I) levels are primarily associated with increased high density lipoprotein (HDL) fractional catabolic rate (FCR), the factors that regulate the clearance of HDL from the plasma are unclear. In this study, the effect of lipid composition of reconstituted HDL particles (LpA-I) on their rate of clearance from rabbit plasma has been investigated. Sonicated LpA-I containing 1 to 2 molecules of purified human apoA-I and 5 to 120 molecules of palmitoyl-oleoyl phosphatidylcholine (POPC) exhibit similar charge and plasma FCR to that for lipid free apoA-I, 2.8 pools/day. Inclusion of 1 molecule of apoA-II to an LpA-I complex increases the FCR to 3.5 pools/day, a value similar to that observed for exchanged-labeled HDL3. In contrast, addition of 40 molecules of triglyceride, diglyceride, or cholesteryl ester to a sonicated LpA-I containing 120 moles of POPC and 2 molecules of apoA-I increases the negative charge of the particle and reduces the FCR to 1.8 pools/day. Discoidal LpA-I are the most positively charged lipoprotein particles and also have the fastest clearance rates, 4.5 pools/day. Immunochemical characterization of the different LpA-I particles shows that the exposure of an epitope at residues 98 to 121 of the apoA-I molecule is associated with an increased negative particle charge and a slower clearance from the plasma. We conclude that the charge and conformation of apoA-I are sensitive to the lipid composition of LpA-I and play a central role in regulating the clearance of these lipoproteins from plasma. conformation regulate the clearance of reconstituted high density lipoprotein in vivo.

Apolipoprotein A-I↗
PubMedDate not supplied

[Lipid parameters of the skin, cerebellum, and medulla oblongata during immersion stress in rats].

The influence of short-form water immersion stress of rats on lipids in the skin, the cerebellum and the medulla oblongata was studied. The level of total lipids and absolute and relative contents of the main lipid fractions (phospholipids, nonesterified cholesterol, free fatty acids, triglycerides, and cholesterol esters) were measured. Stress induced delayed changes of the lipid component of the skin. The first significant changes of lipid fractions were only observed 20 h later after the stress procedure. These changes were retained (being at nearly constant levels) till the end of the second day. The decrease in contents of total lipids and esterified cholesterol was revealed in the cerebellum of stressed rats (in comparison to these levels in control rats). These results suggest the involvement of cholesterol metabolic system in the stress reaction. The content of total lipids decreased also in the medulla oblongata. However, levels of the main lipid fractions changed differently. The content of diglycerides increased and the content of cholesterol decreased. The data obtained suggest that degradation of triglycerides is the principle pathway of metabolic conversions of lipids. Free fatty acids formed during these processes are probably involved in the synthesis of phospholipids and cholesterol esters. The data indicate absolutely different mechanisms of interrelations between individual lipid fractions in the brain regions studied. Various roles of the brain structures in the stress response of the body may account for the differences revealed.

Animals↗
PubMed2000

Structural and functional aspects of nuclear lipids in normal and tumor cells.

This review summarizes available data on the structural and functional role of neutral lipids and phospholipids in normal and tumor eukaryotic cells. The role of acidic phospholipids (cardiolipin, phosphatidylinositol, and phosphatidylglycerol) in regulation of activities of DNA- and RNA-polymerases, DNA-topoisomerases I and II, DNA-methylases, and replication initiation proteins (dnaA and T-antigen) is discussed. The role of sphingolipids is emphasized considering, on one hand, the involvement of sphingosines in signal transduction, chromatin association-dissociation, and regulation of DNA and RNA synthesis and protein kinase C and, on the other hand, participation of ceramides and dihydroceramides in apoptosis. The possible role of sphingomyelin, sphingosine, cardiolipin, and diglycerides in the contacts of DNA loops with nuclear matrix is analyzed. Lipid hormones indirectly influence supercoiled DNA conformation; the effect of hormones on metabolism of phospholipids and neutral lipids in chromatin and nuclear matrix is reviewed. Characteristics of lipid composition in chromatin and nuclear matrix of the tumor cells are discussed.

Cell Nucleus↗
PubMed1975

Reactivation of the lipid-depleted pyruvate oxidase system from Escherichia coli with cell envelope neutral lipids.

The pyruvate oxidase system of Escherichia coli is composed of a soluble flavoprotein, pyruvate oxidase (EC 1.2.2.2, pyruvate:ferricytochrome b1 oxidoreductase), and an electron transport system associated with the cell envelope-membrane fraction. The membrane particles contain 15% lipid by weight. Fractionation of the lipids revealed that abut one-third are neutral lipids and two-thirds are phospholipids. The relative ratio of ubiquinone to menaquinone within the neutral lipid fraction is 15:1 on a molar basis. Removal of the lipids from the membrane particles by extraction with aqueous acetone or hydrolysis of the phospholipids by treatment with Bacillus cereus phospholipase C results in a complete loss of electron transport activity. Analysis of the particles extracted with aqueous acetone revealed that practically all the neutral lipids and 65% of the phospholipids are removed by this treatment. Phospholipase treatment results in a loss of 75% of the membrane phospholipid phosphorus; however, the diglycerides and the neutral lipids produced by phospholipase hydrolysis remain associated with the particles. Addition of neutral lipid and a detergent, hepta-DL-alanyl dodecylamide to the acetone-extracted material results in a restoration of 37% of the original particle activity. Addition of neutral lipid and hepta-DL-alanyl dodecylamide to phospholipase-treated particles completely restores the original electron transport activity. Furthermore, addition of ubiquinone from either yeast (UQ6) or E. coli (UQ8) will restore pyruvate oxidase activity when the quinones are supplemented with photoinactivated neutral lipid. No restoration of activity to phospholipase-treated particles is noted upon the addition of either menaquinone 6 or menaquinone 8 to the reconstitution system. In fact, these compounds appear to suppress restoration of activity when they are added to reaction mixtures containing neutral lipid and phospholipase-treated particles.

Cell Membrane↗
PubMed2001

Chromatin-bound cardiolipin: the phospholipid of proliferation.

Chromatin-bound lipids, cardiolipin (CL), diglycerides, cholesterol, and cholesterol esters, together with nonhistone proteins, play a key role in structural and functional organization of the chromatin genome during various stages of evolution. There are two pools of chromatin lipids, namely loosely- and tightly-bound lipids. The entire chromatin cardiolipin is bound to DNA. The CL molecule has a common 'interphosphate' structural motive with DNA, i.e. DNA and CL phosphate moieties separated from each other with six chemical bonds and equidistant, which is important for CL functional role, the regulation of gene expression. The CL dominates in the DNA of the active genome but not in the DNA of the repressed genome. The amount of CL in the DNA from the repressed genome of pigeon erythrocytes (one CL molecule per 20 nucleosomes) is 20 times less than in the DNA from the active genome of rat thymus and liver and in the DNA of transformed cells. Cardiolipin provides A-form DNA in the complex with RNA-polymerase, which is necessary for transcription. The biological and structural function of cardiolipin can be realised only when unsaturated fatty acyl residues are present in its structure.

Animals↗
PubMed2001

[The effect of acute hypobaric hypoxia on the autolytic changes in lipids of the gray and white substance of white rats].

Effects of acute hypobaric hypoxia (1:30 hrs. at 190-200 mm Hg) on the autolytic changes in lipids of the gray and white substance of the brain were evaluated in an experiment with white rats. Total lipids (TL) in the autolysing segments of the brain of rats sacrificed immediately following the end of hypoxia were noticed to undulate downward starting from minute 10 of incubation, whereas in the gray substance an insignificant TL loss occurred no earlier than in 4 hrs. with return to baseline values by the end of the observation (in 24 hrs.). Hypobaric hypoxia materially reduces phospholipids (PL) in these sections of the brain typically following 24 hrs. of autolysis with concomitant buildup of diglycerides (DG) and free fatty acids (FFA), and triglycerides (TG) in the white substance. There was also evidence of cholesterol (Ch) reduction both in the gray and white substances paralleled by buildup of cholesterol ethers (ChE) in the gray substance. However, after 24-hr incubation in the autolysing brain structures the total cholesterol displayed a strong trend upward. It is presumed that pre-exposure to hypobaric hypoxia enhances not only the hydrolytic PL degradation in the course of autolysis but also activates the transacylation-type rearrangements within the PL-DG-TG and PL-Ch-ChE in the white and gray substance of rat's brain.

Acute Disease↗
PubMed2001

Postnatal changes in the brain lipids, glycolipids and gangliosides of rats exposed to arrack/ethanol during gestation and lactation.

Effects of exposure of an alcoholic beverage (arrack and its equivalent quantity of alcohol throughout pregnancy and lactation on brain lipids were investigated. Female rats were exposed to arrack (12.00 ml/kg body weigh/day) and ethanol (4.00 g/kg body weight day) before conception and throughout gestation and lactation. For 21 days pups were nursed by their own mothers, afterwards they were fed normal laboratory feed. We found that the level of cholesterol, phospholipids, triacylglycerols, free fatty acids, cerebrosides, ceramide dihexosides, ceramide polyhexosides, sulfatids,, mono and diglycosyl diglycerides and gangliosides were increased in the brain of 21st and 45th day pups. The alterations in the glycolipid profile of the brain persisted even when pups were not directly exposed to alcohol. These alterations in the glycolipid and ganglioside metabolism may be associated with the developmental abnormalities of the brain seen in FAS. The elevation produced in the glycolipid profile of arrack administered pups were more than that caused by its equivalent quantity of ethanol. This suggested an interaction of congeners in the arrack with the alcohol.

Animals↗
PubMed2002

Lipid content and fatty acid composition in lemon wax.

Lipids were extracted from lemon wax and fractionated into four classes on a silicic acid glass packed column by thin-layer chromatography (TLC). The free fatty acids, the fatty acid composition and the amount of each separated lipids were determined by capillary column gas chromatography (GC). Total lipids (TL) were 60 mg per 100 g raw weight and the ratio of nonpolar lipids (NPLs): glycolipids (GLs): phospholipids (PLs) was about 47:2:2. The main free fatty acids in lemon wax were hexadecanoic acid, cis-9-octadecenoic acid and cis,cis-9,12-octadecadienoic acid, while in the lipid fractions the main fatty acids were hexadecanoic acid in all the fractions, cis-cis-9,12-octadecadienoic and decanoic acids in triglyceride (TG) fraction, dodecanoic and cis-9-octadecenoic acids in diglyceride (DG) fraction and tetradecanoic, octadecanoic and cis-9-octadecenoic acids in GL and PL fractions. The ratio of unsaturated to saturated fatty acids showed a remarkable difference among these four lipid fractions. In PL and GL fractions this ratio was similar, 47.7% and 47.1% respectively, and in TG fraction it was 42.4% while in DG fraction this value was 23.5%.

Chromatography, Gas↗
PubMedDate not supplied

[Composition of lipids of Actinomyces olivaceus--synthesis of vitamin B 12].

Total cellular lipids of the synthetic of vitamin B12 Act. olivaceus involve predominantly phospholipids (about 70%). Lipid phosphates consist of phosphatidyl ethanol amine and phosphatidyl-2,3-butandiol (over 40 and 30%, respectively) and lower quantities of phosphatidyl inositol olmonomanoside and cardiolipin. The neutral fraction includes the predominating fraction of triglycerides (over 20%) as well as mono- and diglycerides, free fatty acids, hydrocarbons and three fractions similar to waxes, sterines and sterine esters in their Rf values.

Actinomyces↗
PubMed1975

The relationship between the bovine heart mitochondrial adenosine triphosphatase, lipophilic compounds, and oligomycin.

The lipid-free particulate preparations of the mitochondrial ATPase require phospholipid for activity and can be inhibited by oligomycin, as has been demonstrated previously. In this communication a steady state analysis of the activation of a particulate preparation of the ATPase by phospholipids and its subsequent inhibition by oligomycin has been carried out. The relative affinity of the ATPase for purified phospholipids has been determined by measuring the Km for activation (Ka) for several phospholipids. The Ka values varied from 30 to 100 mum. The Vmax in the presence of phosphatides varies from 0.29 to 1.11 mumol ATP hydrolyzed/min/mg of protein; no correlation is noted between the relative affinity of the enzyme for a phospholipid and the V max value. Higher V max values are noted with the more acidic phospholipids, however. Sodium dodecyl sulfate and monoolein also activate with Ka values of 25 and 800 mum, respectively. Diglycerides, however, do not activate. With all lipids the ATPase activity stimulated is oligomycin-sensitive. The Ki values for oligomycin range from 0.1 to 0.6 mum. Oligomycin is a competitive inhibitor with respect to all the phospholipids tested except phosphatidylethanolamine and phosphatidyglycerol. It is also competitive with respect to sodium dodecyl sulfate (k-i equals 0.94 mum). In reciprocal plots of activity versus ATP concentration, with and without oligomycin, an intercept consistent with either mixed or partial noncompetitive inhibition kinetics is noted. Comparable K-i values for oligomycin are obtained when calculated assuming either mixed or partial noncompetitive inhibition. The Km for ATP is the same in the unactivated and the lipid activated particulate ATPase; the value obtained is slightly lower than the Km for ATP in the solubilized, purified ATPase. Using a spectrophotometric assay the time required for activation with phospholipid and inhibition with oligomycin has also been determined. This investigation suggests the possibility that activation of the ATPase is due a position to interact with the water-soluble substrate. Consistent with the above suggestion is the supposition that the lipids do not necessarily confer inhibitor sensitivity to the ATPase, but rather allow an oligomycin-sensitive activity to be expressed.

Adenosine Triphosphatases↗
PubMed2002

[Discrepancies in the measurement of serum pancreatic lipase activities by non-enzymatic and enzymatic assays, and relationships to pseudohyperlipasemia].

I have observed discrepancies in the measurement of serum pancreatic lipase(LIP, Triacylglycerol acylhydrolase, EC 3.1.1.3) activities by non-enzymatic and enzymatic methods using diglyceride(1,2-dilinoleoyl-2-palmitoyl-glycerol, DLPG) as a substrate. The greatest discrepancies were seen in the post-heparin sera of patients with acute coronary syndrome(ACS). It is well-known that serum levels of lipoprotein lipase(LPL, EC 3.1.1.34) and hepatic triglyceride lipase(HTL, EC 3.1.1.3) show a significant increase after the administration of heparin in hemodialysis patients, and even larger quantities of heparin are administered before cardioangiography for ACS. Moreover, inhibitors of LPL and HTL induce almost complete reduction of increased LIP activity in post-heparin serum as measured by enzymatic assays. Pseudohyperlipasemia and positive interference from post-heparin serum LIP activity in enzymatic assays are considered to largely reflect LPL and HTL activities. Therefore, enzymatic reagent kits need improvement.

Acute Disease↗
PubMed1975

[The importance of phosphatidylcholine in the binding of anti-D to human erythrocyte ghost membrane (author's transl)].

Incubation of Rh positive ghosts with phospholipase A2 and C abolished the adsorption of Rh antibodies on the ghosts; incubation with phospholipase D, however, did not affect their adsorption and none of these phospholipases affected the adsorption of antibodies of the ABO system. The impairment of antigen-antibody-reaction in Rh positive ghosts treated with phospholipase corresponds to the absence of the antigen-antibody reaction with the membrane protein associated with Rh characteristics in the Schultz-Dale-Test. The chromatogram of the phospholipids extracted from those stromata treated with various phospholipases and those not treated showed different patterns. After incubation with phospholipase-A2 the lecithin and cephalin streaks were reduced and in addition lysophosphatide and fatty acid streaks were detected. In the case of phospholipase C the lecithin and cephalin streaks were further reduced while diglyceride streaks made their appearance. The phospholipid extracts from those stromata treated with phospholipase D and those not treated were identical. Phospholipase C reduced the values of lipid phosphorus more than did phospholipase A2, while phospholipase D did not reduce them at all. This study supports the results of other investigators who have postulated that the Rh antigens are located in a lipoprotein on the membrane of the human erythrocyte. The antigen-antibody-reaction seems to require a precise protein-phospholipid interaction.

Binding Sites, Antibody↗
PubMed1992

Triglyceride metabolism in 3T3-L1 cells. An in vivo 13C NMR study.

13C nuclear magnetic resonance spectroscopy has been used to study triglyceride metabolism in 3T3-L1 cells incubated with [1-13/14C] acetate, myristate, palmitate, stearate, or oleate. Labeled cells embedded in agarose filaments were perfused in a specially fitted NMR tube within the spectrometer magnet. Incubation of 3T3-L1 cells with a specific fatty acid enriched the cellular triglycerides with that fatty acid; the NMR signal observed in the carbonyl region of the cell spectrum was due in large part to that fatty acid. NMR data demonstrated that cellular enzymes preferentially esterified saturated fatty acids at the glyceride sn-1,3 position and unsaturated fatty acids at the sn-2 position. cellular triglyceride hydrolysis by hormone-sensitive lipase was monitored by measuring the decrease in the integrated intensities of resonances arising from fatty acyl carbonyls esterified at glycerol carbons sn-1,3 and sn-2. Under basal conditions, the time courses were first-order, and the average rates were 0.14% of signal/min at both carbonyl positions. Under isoproterenol stimulated conditions, these rates were still first-order and increased 6.4-fold at the sn-1,3 position and 2.4-fold at the sn-2 position. The observation that the hydrolysis time courses were first-order suggested that only a small amount of cellular triglyceride was available to hormone-sensitive lipase, supporting the view that lipolytic enzymes operate at lipid surfaces where only small amounts of neutral lipid may be soluble. Attempts to correlate the measured rates with the rates of hydrolysis at the sn-1,3 and sn-2 positions were hindered by the fact that the chemical shifts of the carbonyl carbons of the diglyceride hydrolysis product did not overlie those of the triglyceride. Analysis of hydrolysis kinetics revealed that hormone-sensitive lipase exhibited little preference for a particular esterified fatty acid under basal conditions; however, under stimulated conditions, the enzyme exhibited a preference for certain triglyceride species.

3T3 Cells↗
PubMed1992

Inhibition of Acanthamoeba myosin I heavy chain kinase by Ca(2+)-calmodulin.

The actin-activated Mg(2+)-ATPase activity of Acanthamoeba myosins I depends on phosphorylation of their single heavy chains by myosin I heavy chain kinase. Kinase activity is enhanced > 50-fold by autophosphorylation at multiple sites. The rate of kinase autophosphorylation is increased approximately 20-fold by acidic phospholipids independent of the presence of Ca2+ and diglycerides. We show in this paper that Ca(2+)-calmodulin inhibits phospholipid-stimulated autophosphorylation of myosin I heavy chain kinase and hence also inhibits the catalytic activity of unphosphorylated kinase in the presence of phospholipid. Ca(2+)-calmodulin does not inhibit kinase activity in the absence of phospholipid. Micromolar Ca(2+)-calmodulin also inhibits binding of myosin I heavy chain kinase to phospholipid vesicles and purified plasma membranes. Proteolytic removal of a 7-kDa NH2-terminal segment from the 97-kDa kinase prevents binding of both calmodulin and phospholipid; therefore, we propose that they bind to the same or overlapping sites. These data provide a mechanism by which Ca2+ could inhibit the actin-activated Mg(2+)-ATPase activity of the myosin I isozymes in vivo and thus regulate myosin I-dependent motile activities.

Acanthamoeba↗
PubMed1992

Platelet-activating factor stimulates arachidonic acid release and enhances thromboxane B2 production in intact fetal rat brain ex vivo.

The ability of brain preparations from 20-day-old rat fetuses to synthesize eicosanoids in the presence of platelet activating factor (PAF) was investigated. A rise (49%) in thromboxane B2 (TxB2; the stable thromboxane A2 metabolite) was observed after 30 min in the presence of 0.6 microM PAF. Repetitive administration of PAF did not rise TxB2 production above a certain level, suggesting desensitization. 1-O-alkyl, sn-glycero-3-phosphocholine (lyso-PAF) at 0.6 microM had no effect, whereas selective PAF antagonists, i.e., BN52021, BN50739 and BN50727, or indomethacin, a general cyclooxygenase inhibitor, blocked completely TxB2 synthesis. The calcium ionophore A23187 (10 microM) stimulated production of TxB2, prostaglandin E2 and 6-keto-prostaglandin F1 alpha eicosanoids, whereas extracellular calcium deprivation did not impair eicosanoid release. The effects of PAF and A23187 on TxB2 synthesis were not additive and were not dependent on extracellular calcium. Chelation of intracellular Ca++ by Fluo-3/AM reduced production of TxB2 and prostaglandin E2 eicosanoids. Fluo-3/AM also blocked effectively PAF-dependent TxB2 release, indicating that production of TxB2 was almost entirely dependent on free intracellular calcium levels. PAF-dependent changes in brain phospholipids, prelabeled with [3H]arachidonic acid, were examined. One hour after in vivo injection of the isotope, fetal brains were removed and incubated in vitro for 30 min with carbamyl-PAF. Radioactivity in arachidonic acid and diglyceride fractions increased (35% and 30%, respectively), whereas radioactivity in phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol decreased. BN50726 antagonist abolished the effect of PAF. The radioactivity in poly-phosphoinositides was diminished (30-40% decrease) after PAF addition.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Lipiduria in the nephrotic syndrome].

A study was made of urine lipids and their fractions in chronic glomerulonephritis (CGN) and renal amyloidosis with nephrotic syndrome (NS). 91 patients suffering from NS were examined. 2 subgroups were distinguished among these patients: with CGN of the nephrotic type and with the nephrotic stage of renal amyloidosis. The reference groups were made up of patients with latent CGN and healthy subjects. Measurements were made in the blood and urine of total lipids (TL) and their fractions--phospholipids (LP), free cholesterol (FC), mono- and diglycerides, triglycerides (TG), and cholesterol esters (CE). The presence of the NS was attended by a rise in the blood of TL concentration, relative content of FC, TG and by a decline of RL and CE, with the decrease of the relative content being more manifest in amyloidosis. Nephrotic lipiduria was largely characterized by an increase of the concentration of TL and of the relative content of PL, with the changes of the latter parameter being mostly characteristic of CGN patients. Thus, NS was associated with a high excretion of lipids with urine which is likely to reflect their elevated filtration under nephrotic hyperlipidemia. Still, in nephropathies whose pathogenesis is determined by an important role of inflammatory and membrane-destructive processes, of definite role is also the local (renal) formation of PL.

Adolescent↗
PubMed1978

[Metabolism of (1-14C)-palmitic acid in the cat's brain].

Following injection into the cerebral ventricles of conscious cats, (1-14C) palmitic acid was rapidly taken up and incorporated into a variety of brain lipids. The peak of uptake of (1-14C) palmitic acid, about 50% of injected radioactive material, into the brain tissue was obtained within the first 24 h following its administration. Thereafter, the radioactivity slowly decreased reaching the least value by the end of the second week. The most heavily labelled lipids were the phospholipids, while the free fatty acids were appreciably labelled. Small percentage of the radioactive material was found in monoglycerides, diglycerides and triglycerides. The least incorporation was into cholesterol esters.

Animals↗