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PubMed1997

Accumulation of arachidonic acid in ischemic/reperfused cardiac tissue: possible causes and consequences.

Under physiological conditions, the content of unesterified arachidonic acid in cardiac tissue is very low. The bulk of arachidonic acid is present in the membrane phospholipid pool. Incorporation of arachidonic acid into phospholipids (reacylation) and liberation of this fatty acid from the phospholipid pool (deacylation) are controlled by a set of finely tuned enzymes, including lysophospholipid acyltransferase and phospholipase A2. At present, at least three subtypes of phospholipase A2 have been identified in cardiac structures, i.e., a low molecular mass group II phospholipase A2, a cytoplasmic high molecular mass phospholipase A2 and a plasmalogen-specific phospholipase A2. Cessation of flow to the heart (ischemia) gives rise to net degradation of membrane phospholipids accompanied by accumulation of fatty acids, including (unesterified) arachidonic acid. Restoration of flow to the previously ischemic cells results in a continued accumulation of fatty acids. The mechanism(s) underlying net phospholipid degradation in ischemic/reperfused myocardial tissue is (are) incompletely understood. Impaired reacylation, enhanced hydrolysis of phospholipids, or a combination of both may be responsible for the phenomena observed. Elevated tissue levels of arachidonic acid may exert both direct and indirect effects on the affected myocardium and healthy cardiac cells adjacent to the injured cardiomyocytes. Indirect effects might be evoked by arachidonic acid metabolites, i.e., eicosanoids. Arachidonic acid may directly influence ion channel activity, substrate metabolism and signal transduction, thereby affecting the functional characteristics of the ischemic/reperfused myocardium.

Acylation↗
PubMed2000

High dietary levels of a conjugated linoleic acid mixture alter hepatic glycerophospholipid class profile and cholesterol-carrying serum lipoproteins of rats.

To investigate the body composition, hepatic lipids, and serum lipoproteins in response to graded levels of a conjugated linoleic acid (CLA) mixture added to a high linoleate diet, adult male Sprague-Dawley rats were randomly assigned into four dietary groups of 10 rats each and fed for 5 weeks controlled amounts of diets containing 0%, 1%, 3%, or 5% of a CLA mixture in exchange for sunflower oil. The various dietary lipid treatments did not significantly influence growth and body partitioning, although there was a trend toward decreased contents of extractable lipids in carcass (whole bled body without liver and gut) with increasing CLA. When carcass lipids of CLA-treated rats were extracted, a distinct accumulation of total CLA was observed. A dietary level of 1% CLA mixture exhibited only weak effects on hepatic glycerophospholipid levels. CLA levels of 3% and 5% caused distinct changes in phospholipid subclass distribution. These changes were reduced levels of lysophosphatidylethanolamine (LPE) and ethanolamine plasmalogen (EPL) and increased levels of phosphatidylcholine (PC). Further, a 5% level of CLA increased the hepatic concentration of phosphatidylserine (PS) compared with the other treatments. The incorporation of total CLA into individual phospholipids followed a dose-responsive manner. The extent of incorporation of CLA was not the same among the glycerophospholipid species analyzed, the order being cardiolipin > phosphatidylethanolamine and PC > LPE/EPL > phosphatidylinositol > PS. Further, CLA increased the proportions of n-3 fatty acids in the individual glycerophospholipids. High CLA diets containing 3% and 5% of a CLA mixture were associated with increased activity of catalase in the peroxisome-enriched cell fraction of liver and exhibited marked reductions of cholesterol in the low and high density lipoproteins relative to rats receiving no CLA.

Journal Article↗
PubMed1989

Lipid metabolism in Trichuris globulosa (Nematoda).

Adult males and females of Trichuris globulosa, an intestinal nematode parasite of goats, were studied for their lipid composition, capability of incorporation of (Na)-1-14C-acetate into different lipid classes and the activity of certain key enzymes of lipid metabolism. The parasite possesses a large variety of lipids including certain complex lipids. These are phosphatidylcholine (PC), diphosphatidylglycerol (cardiolipin), lysophosphatidylcholine (LPC), lysophosphatidylethanolamine (LPE), phosphatidylserine (PS), phosphatidylinositol (PI), plasmalogens (choline + ethanolamine), mono-, di- and triacylglycerols, free and esterified cholesterol, non-esterified fatty acids (NEFA), gangliosides, cerebrosides (glycosyl ceramide) and sulphuric acid esters of cerebrosides (sulphatides). The females contain more lipids than males, particularly the acylglycerols and phospholipids, possibly to meet the energy requirement and structural entities for the daily production of large numbers of eggs. Incorporation studies of labelled substrate, sodium-1-14C acetate demonstrate that the adult female has extremely active mechanisms for biosynthesizing these lipids. Most of the labels are found in PC, PE, SM, acylglycerols, NEFA, gangliosides, cerebrosides and sulphatides. Cholesterol, although a minor component of the parasitic lipids, incorporates large amount of label and also undergoes fast turnover. Kinetic analysis of the incorporation by measuring the rate constant (k) and half life (t1/2) reveals that gangliosides are the fastest biosynthesizing and turning over lipids, although they constitute only 0.1% of the total lipids. The presence of important enzymes of lipid biosynthesis, glucose-6-phosphate dehydrogenase, malate dehydrogenase and hydroxymethyl glutaryl-CoA reductase and an enzyme of lipid ester hydrolysis, triacylglycerol lipase, is also established in T. globulosa. Michaelis-Menten kinetic characteristics of the parasitic enzymes (Km, Vmax, v and the first order rate constant, k) are comparable with those of rat liver homogenates.

Animals↗
PubMed1990

Dipolar solvent relaxation on a nanosecond time scale in ether phospholipid membranes as determined by multifrequency phase and modulation fluorometry.

The present study reports on the observation of dipolar solvent relaxation in phospholipid membranes using multifrequency phase and modulation fluorometry. We measured the time-resolved emission spectra of 6-propionyl-2-(dimethylamino)naphthalene (PRODAN) in artificial bilayer membranes of chemically defined acyl-, alkyl-, and alkenyl-substituted phospholipids at 15 degrees C. 1-Palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine, 3-O-hexadecyl-2-oleoyl-sn-glycero-1-phosphocholine, or 1-O-hexadec-1'-enyl-2-oleoyl-sn-glycero-3-phosphocholine (plasmalogen) were used as matrix lipids. The chemical structures of these lipids differ only with respect to the type of linkage (carboxyl ester, ether, or enol ether bond) between glycerol and the hydrophobic chain linked to the primary hydroxyl of glycerol. At 15 degrees C, all the lipids are in the liquid crystalline state. PRODAN probably localizes at the hydrophobic-hydrophilic interface of the phospholipid bilayer [Chong, P. L. (1988) Biochemistry 27, 399-404]. We found faster solvent relaxation of PRODAN in membranes composed of the ether lipid compared to that in the ester lipid membranes. On the other hand, the fluorescence anisotropies of the label were very similar, showing that the motion of the label itself is similar in ether and carboxyl ester lipids. We conclude that the spectral differences observed for PRODAN in ether and ester lipids could be due to different dipolar relaxation of the immediate surroundings of the label, i.e., reorientation of lipid dipoles in the glycerol region and of water molecules residing therein.

Kinetics↗
PubMed1981

Phase behavior of ether lipids from Clostridium butyricum.

Ether lipids have been isolated from the phospholipid fraction of Clostridium butyricum IFO 3852 cells which had been grown in media devoid of biotin with added elaidic acid or oleic acid. The plasmalogen form of phosphatidylethanolamine (plasmenylethanolamine) from elaidate-grown cells was highly enriched with 18:1 in both the alk-1-enyl and acyl chains. A transition from the gel to liquid-crystalline state, with a peak maximum (Tm) at 33 degrees C and enthalpy delta H = 5.7 kcal/mol, was observed by differential scanning calorimetry. With the fluorescent probes cis- and trans-parinaric acids, transitions were observed at 33 degrees C on heating and at 29 degrees C on cooling. These transition temperatures are 5-6 degrees C lower than those reported for the corresponding diacyl lipid, dielaidoylphosphatidylethanolamine. A similar study of the phase behavior of both the elaidate-enriched and oleate-enriched glycerol acetal derivative of plasmenylethanolamine from C. butyricum revealed a large hysteresis of 12.5-16 degrees C. Hysteresis in the polar head group motion was also observed by 31P nuclear magnetic resonance. The elaidate-enriched lipid, which melted between 28 and 33 degrees C, appears to undergo supercooling prior to the transition to the gel state at about 18-13 degrees C, depending on the scanning rate. The formation of a more ordered gel state relative to plasmenylethanolamine was indicated by a 2-fold increase in delta H. Electron microscopy revealed a marked reorganization from typical multilamellar liposomes above Tm to large needle-like structures below Tm. The oleate-enriched glycerol acetal lipid formed the gel phase at -4 degrees C, which is 10 degrees C above the transition temperature reported for dioleoylphosphatidylethanolamine. Stabilization of oleate-enriched glycerol acetal lipid bilayers may result from hydrogen bonding between polar head groups. The relationship of the phase behavior of the ether lipids to the lipid composition and phase behavior of C. butyricum membranes is discussed.

Calorimetry, Differential Scanning↗
PubMed1998

Generalized peroxisomal disorder in male twins: fatty acid composition of serum lipids and response to n-3 fatty acids.

Male, identical twins presented with hypotonia, hypoglycaemia, dysmorphic facies, feeding problems, discoloured stools, hepatomegaly, and nephrolithiasis. Elevated blood levels of very long-chain fatty acids and bile acids suggested a peroxisomal disorder. Plasmalogen biosynthesis in cultured fibroblasts was reduced. Morphologically distinct peroxisomes were undetectable in liver. Twin 1 suffered from nephrocalcinosis and severe infection, and died at 18 months of age. Twin 2 was blind and physically severely retarded with epilepsy, but survived up to the age of 5 years. Studies of the fatty acid composition of serum lipids showed barely detectable values of eicosapentaenoic (EPA) and docosahexaenoic acid (DHA). During long-term treatment with these n-3 fatty acids, started at age 10 months, the fatty acid profile of the serum lipids was improved or normalized. Since n-3 fatty acids are essential elements in normal development, notably of the nervous system, we suggest that treatment with EPA and DHA should be started as early as possible in general peroxisomal disorders.

Diseases in Twins↗
PubMed2001

Brain membrane phospholipid alterations in Alzheimer's disease.

Studies have demonstrated alterations in brain membrane phospholipid metabolite levels in Alzheimer's disease (AD). The changes in phospholipid metabolite levels correlate with neuropathological hallmarks of the disease and measures of cognitive decline. This 31P nuclear magnetic resonance (NMR) study of Folch extracts of autopsy material reveals significant reductions in AD brain levels of phosphatidylethanolamine (PtdEtn) and phosphatidylinositol (PtdIns), and elevations in sphingomyelin (SPH) and the plasmalogen derivative of PtdEtn. In the superior temporal gyrus, there were additional reductions in the levels of diphosphatidylglycerol (DPG) and phosphatidic acid (PtdA). The findings are present in 3/3 as well as 3/4 and 4/4 apolipoprotein E (apoE) genotypes. The AD findings do not appear to reflect non-specific neurodegeneration or the presence of gliosis. The present findings could possibly contribute to an abnormal membrane repair in AD brains which ultimately results in synaptic loss and the aggregation of A beta peptide.

Aged↗
PubMed1999

Rhizomelic chondrodysplasia punctata, a peroxisomal biogenesis disorder caused by defects in Pex7p, a peroxisomal protein import receptor: a minireview.

Rhizomelic chondrodysplasia punctata (RCDP) is a lethal autosomal recessive disease corresponding to complementation group 11 (CG11), the second most common of the thirteen CGs of peroxisomal biogenesis disorders (PBDs). RCDP is characterized by proximal limb shortening, severely disturbed endochondrial bone formation, and mental retardation, but there is an absence of the neuronal migration defect found in the other PBDs. Plasmalogen biosynthesis and phytanic acid oxidation are deficient, but very long chain fatty acid (VLCFA) oxidation is normal. At the cellular level, RCDP is unique in that the biogenesis of most peroxisomal proteins is normal, but a specific subset of at least four, and maybe more, peroxisomal matrix proteins fail to be imported from the cytosol. In this review, we discuss recent advances in understanding RCDP, most prominently the cloning of the affected gene, PEX7, and identification of PEX7 mutations in RCDP patients. Human PEX7 was identified by virtue of its sequence similarity to its Saccharomyces cerevisiae ortholog, which had previously been shown to encode Pex7p, an import receptor for type 2 peroxisomal targeting sequences (PTS2). Normal human PEX7 expression rescues the cellular defects in cultured RCDP cells, and cDNA sequence analysis has identified a variety of PEX7 mutations in RCDP patients, including a deletion of 100 nucleotides, probably due to a splice site mutation, and a prevalent nonsense mutation which results in loss of the carboxyterminal 32 amino acids. Identification of RCDP as a PTS2 import disorder explains the observation that several, but not all, peroxisomal matrix proteins are mistargeted in this disease; three of the four proteins deficient in RCDP have now been shown to be PTS2-targeted.

Animals↗
PubMed2003

Effect of hypo- and hyperthyroid states on phospholipid composition in developing rat heart.

The aim of this study was to examine the effect of hypo- and hyperthyroidism on the phospholipid composition in developing rat heart. The hypothyroid state (PTU) was induced by 0.05% 6-n-propyl-2-thiouracil in drinking water given to nursing mothers from the postnatal day 2-21. The hyperthyroidism (T3) was made by daily injection of 3,3',5-triiodo-L-thyronine (10 microg/100 g body wt) to newborns in the same time period. Age matched intact littermates were taken as euthyroid controls. PTU decreased the concentration of total phospholipids (PL), choline phosphoglycerides (PC), ethanolamine phosphoglycerides (PE) and diphosphatidylglycerol (DPG) and increased the proportion of plasmalogen component of PE (PLPE). T3 increased the concentration of PL, PC, PE, DPG and decreased PLPE in comparison with euthyroid controls. The ratio of saturated/unsaturated fatty acids (FA) in PE was decreased in PTU and increased in T3 group. The ratio of n-6/n-3 polyunsaturated FA in PC, PE and phosphatidylinositol (PI) was increased in PTU due to increase of 18:2n-6 and decrease of 22:6n-3 proportion. T3 decreased this ratio because of decline in 20:4n-6 and rise in 22:6n-3 proportion. Both hypo- and hyperthyroidism decreased the ratio of 20:4n-6/18:2n-6 in the majority of phospholipids. PTU decreased the unsaturation index in PC, PI and phosphatidylserine. It is concluded that thyroid state plays an essential role in the development of membrane phospholipid components in cardiac membranes during the early postnatal period.

Animals↗
PubMed1991

31P magnetic resonance phospholipid profiles of neoplastic human breast tissues.

Phospholipids from malignant, benign and noninvolved human breast tissues were extracted by chloroform-methanol (2:1) and analysed by 31P MR spectroscopy at 202.4 MHz. Thirteen phospholipids were identified as constituents of the profiles obtained among the 55 tissue specimens analysed. Observed patterns in phospholipid tissues profiles were distinct, allowing qualitative characterisation of the three tissue groups. Multivariate analysis of lysophosphatidylcholine (LPC) and an uncharacterised phospholipid were shown to be independently significant in predicting benign tissue histology as either fibrocystic disease or fibroadenoma in 92% of cases. Univariate analysis of relative mole-percentage of phosphorus concentrations of individual phospholipids using the Scheffé comparison procedure revealed that in malignant tissues, phosphatidylethanolamine was significantly elevated compared to benign (+ 32%) and noninvolved tissues (+ 22%). Phosphatidylinositol (+ 33%) and phosphatidylcholine plasmalogen (PC plas) (+ 25%) were increased in malignant compared to benign and LPC was decreased (-44%) in malignant compared to noninvolved. LPC was significantly depressed (-39%) in benign tissue compared to normal. Phospholipid indices computed to further characterise the three tissue groups showed PC plas/PC elevated in malignant tissue compared to benign and PE plas/PE depressed in malignant tissue compared to noninvolved. These findings support previous investigations reporting that the alkyl-phospholipid analogues of phosphatidylcholine are released by malignant tissues and that levels of ethanolamine are elevated in malignant tissues. Indices describing the choline-containing phospholipids showed that these lipids are depressed significantly in malignant tissue relative to healthy tissue.

Breast↗
PubMed2004

Involvement of MAPK pathway in hypoxia-induced up-regulation of urokinase plasminogen activator receptor in a human prostatic cancer cell line, PC3MLN4.

Clinical studies have shown that tumor hypoxia is associated with invasive growth and metastasis and may be an important prognostic factor adversely influencing survival in patients with tumors. To investigate the mechanisms involved in hypoxia-induced invasive growth and metastasis, hypoxia-mediated urokinase plasmalogen activator receptor (uPAR) expression, cellular invasiveness, and mitogen activated protein kinase (MAPK) activation were measured in a prostate cancer cell line, PC3MLN4. The levels of uPAR expression and cellular invasiveness were increased in hypoxic cells. Hypoxia-induced cellular invasiveness was blocked by an anti-uPAR monoclonal antibody. Phosphorylations of ERK and p38 kinases were also more extensive in hypoxic cells than in normoxic cells. Hypoxia-induced uPAR up-regulation was inhibited by pre-treatments with a specific inhibitor of MEK, PD98059 and a specific inhibitor of p38 MAP kinase, SB203580. Cell growth also increased in hypoxic cells. From these results, hypoxia increased tumor cell invasion by up-regulating uPAR expression, which might be mediated through ERK and p38 kinase signaling pathways in PC3MLN4 prostate cancer cell line.

Animals↗
PubMed2001

Prenatal and postnatal development of peroxisomal lipid-metabolizing pathways in the mouse.

The ontogeny of the following peroxisomal metabolic pathways was evaluated in mouse liver and brain: alpha-oxidation, beta-oxidation and ether phospholipid synthesis. In mouse embryos lacking functional peroxisomes (PEX5(-/-) knock-out), a deficiency of plasmalogens and an accumulation of the very-long-chain fatty acid C(26:0) was observed in comparison with control littermates, indicating that ether phospholipid synthesis and beta-oxidation are already active at mid-gestation in the mouse. Northern analysis revealed that the enzymes required for the beta-oxidation of straight-chain substrates are present in liver and brain during embryonic development but that those responsible for the degradation of branched-chain substrates are present only in liver from late gestation onwards. The expression pattern of transcripts encoding enzymes of the alpha-oxidation pathway suggested that alpha-oxidation is initiated in the liver around birth and is not active in brain throughout development. Remarkably, a strong induction of the mRNA levels of enzymes involved in alpha-oxidation and beta-oxidation was observed around birth in the liver. In contrast, enzyme transcripts that were expressed in brain were present at rather constant levels throughout prenatal and postnatal development. These results suggest that the defective ether phospholipid synthesis and/or peroxisomal beta-oxidation of straight-chain fatty acids might be involved in the pathogenesis of the prenatal organ defects in peroxisome-deficient mice and men.

Animals↗
PubMed1966

Changes in lipid composition of the maturing rat testis.

1. The lipids and fatty acids of the lipids of testes of rats aged 4 weeks to 6 months were separated and analysed. 2. A decrease in concentration of triglyceride was noted, but there was no significant change in the concentration of phospholipids, plasmalogen or cholesterol during this time. 3. There were no significant differences in the total lipid concentration of palmitic acid, stearic acid, linoleic acid, arachidonic acid and docosatetraenoic acid between the various age groups. 4. A decrease in the concentration of oleic acid in the phosphatide and triglyceride fractions and an increase in the concentration of docosapentaenoic acid (characterized as the Delta4,7,10,13,16-isomer) in phosphatides but not in triglyceride were observed during the maturation period. 5. Histological studies indicated that the lipid changes occurred at the same time as the appearance and maturation of the spermatids.

Animals↗
PubMed1966

The polyphosphoinositides and other lipids of peripheral nerves.

1. A detailed lipid analysis of the peripheral nerves of the crab (claw, leg), lobster (claw, leg), cow (splenic), hen, rabbit, sheep and monkey (sciatic) is presented. 2. The so-called ;myelinic lipids', cholesterol, sphingomyelin, ethanolamine plasmalogen and phosphatidylserine, occurred in the highest proportion in the lipids of vertebrate myelinated nerves, whereas the percentage of lecithin was greatest in the lipids of non-myelinated nerve fibres of both vertebrates and invertebrates. 3. Triphosphoinositide was found in all nerves examined and its concentration in the extracted lipids supports the concept that it is predominantly localized in the myelin sheath. 4. In crustacean nerve 12-14% of the phospholipids was in the form of alkyl ether phospholipids, which in the lobster were approximately half choline-containing and half ethanolamine-containing.

Animals↗
PubMed1966

The lipids of mammalian pancreas.

1. The total lipids of ox and guinea-pig pancreas were fractionated on silicic acid columns. 2. The high lipid content of both tissues was due to triglyceride. The major fatty acids of this triglyceride were stearic acid, palmitic acid and oleic acid. 3. The pattern of individual phospholipids resembled that of liver, though pancreas contained more plasmalogen.

Animals↗
PubMed1967

Lipids of the adrenal medulla. Lysolecithin, a characteristic constituent of chromaffin granules.

1. The lipid composition of microsomes, mitochondria and chromaffin granules, obtained from homogenates of bovine adrenal medulla, has been investigated. 2. The three types of particle showed characteristic differences of phospholipid and cholesterol content. The lipid composition of microsomes and mitochondria resembled that of corresponding particles from other tissues. The chromaffin granules contained 19% of the cholesterol and 14% of the phospholipids of the low-speed supernatant. 3. Thin-layer chromatography indicated the presence of these phospholipids in extracts from each particle: lecithin, lysolecithin, phosphatidylethanolamine (partly plasmalogen), phosphatidylserine, phosphatidylinositol and sphingomyelin. 4. On quantitative analysis of the phospholipids, chromaffin granules were found to contain a high concentration of lysolecithin (17% of the lipid phosphorus). Mitochondria and microsomes, on the other hand, contained very little lysolecithin (less than 2% of the lipid phosphorus).

Adrenal Medulla↗
PubMed1968

Metabolism of phospholipids by spermatozoa and seminal plasma.

1. The hydrolysis of added (32)P-labelled phospholipids by whole ram and bull semen and the separated spermatozoal and plasma components was examined. 2. The ethanolamine phosphoglycerides were rapidly attacked by washed spermatozoa, forming predominantly glycerylphosphorylethanolamine, but with whole semen and seminal plasma a lysophosphatidylethanolamine was also detected. 3. The hydrolysis of lecithin by spermatozoa and plasma was very slow, and glycerylphosphorylcholine was the sole product detected. 4. Ram testicular spermatozoa were comparatively inactive in metabolizing both phospholipids, but ampulla contents showed the same activity as ejaculated semen. 5. Phosphatidylinositol was metabolized by spermatozoa obtained from any portion of the ram reproductive tract and also by seminal plasma. With testicular components, ampulla contents and washed ejaculated spermatozoa, inositol monophosphate, an unidentified phosphate ester and inorganic phosphate were the main products. In contrast, with whole semen and seminal plasma, glycerylphosphorylinositol was the predominant water-soluble phosphate ester. 6. Accessory-gland secretion obtained from vasectomized rams showed a pronounced phospholipase A activity towards ethanolamine phosphoglyceride. 7. On aerobic incubation of whole ram semen there was a decrease in the concentration of all phospholipid classes, although cardiolipin showed the greatest percentage decrease. In the choline phosphoglyceride fraction, this loss was confined to the plasmalogen component. This breakdown of phospholipids was decreased considerably when the spermatozoa were washed, and was not observed when whole bull semen was incubated under similar conditions.

Animals↗