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PubMed1999

Maternal plasma phospholipid polyunsaturated fatty acids in pregnancy with and without gestational diabetes mellitus: relations with maternal factors.

BACKGROUND: The fatty acids arachidonic acid (AA; 20:4n-6) and docosahexaenoic acid (DHA; 22:6n-3) are essential for fetal growth and development, but their metabolism may be altered in insulin resistance. OBJECTIVES: The objectives were to determine maternal plasma phospholipid polyunsaturated fatty acid concentrations in pregnant women receiving dietary therapy for gestational diabetes mellitus (GDM) and to identify maternal factors associated with plasma phospholipid AA and DHA concentrations in the third trimester. DESIGN: Fasting plasma phospholipid fatty acids were determined in women with GDM (n = 15) receiving dietary therapy only and in healthy, pregnant women without GDM (control group, n = 15) at 27-30, 33-35, and 36-39 wk gestation. RESULTS: Maternal plasma phospholipid (as % by wt of total fatty acids and mg/L) linoleic acid (18:2n-6), AA, and 22:5n-6 concentrations did not differ significantly between women with GDM and control subjects. The other n-6 long-chain polyunsaturated fatty acids (% by wt) were lower in GDM subjects than in control subjects. Plasma phospholipid (expressed as % by wt and mg/L) linolenic acid (18:3n-3) and summed precursors of DHA were lower and DHA (% by wt and mg/L), adjusted for dietary DHA intake, was 13% higher in GDM subjects than in control subjects. Maternal blood hemoglobin A1C was inversely related to plasma phospholipid AA (% by wt) (r = -0.56, P = 0.03) in control subjects and positively associated with plasma phospholipid AA (% by wt) in women with GDM (r = 0.76, P = 0.001). Pregravid body mass index was negatively associated with plasma phospholipid DHA (% by wt) in control subjects (r = -0.55, P = 0.04) and in women with GDM with a body mass index (in kg/m2) <30 (r = -0.76, P = 0.007). CONCLUSIONS: This is the first report documenting alterations in maternal plasma phospholipid PUFAs in pregnant women receiving dietary therapy for GDM. In pregnant woman, both with and without GDM, maternal glycemic control and pregravid BMI appear to be significant predictors of plasma phospholipid AA and DHA, respectively, during the third trimester. Additionally, dietary DHA significantly affects phospholipid DHA concentrations.

Arachidonic Acid↗
PubMed2004

Emerging roles for phospholipid transfer protein in lipid and lipoprotein metabolism.

PURPOSE OF REVIEW: This review highlights the recent key advances in our understanding of the role of phospholipid transfer protein in lipid and lipoprotein metabolism. RECENT FINDINGS: The overexpression of human phospholipid transfer protein in mice is associated with an increase in atherosclerosis. This is consistent with earlier studies using mouse models suggesting that phospholipid transfer protein was pro-atherogenic. The presence of phospholipid transfer protein in macrophages and atherosclerotic lesions suggests that it could be either anti-atherogenic by facilitating lipid efflux or pro-atherogenic by facilitating lipid retention. Phospholipid transfer protein may also be a key player in reverse cholesterol transport, as it interacts with the adenosine triphosphate-binding cassette transporter A1 and facilitates lipid efflux from peripheral cells. Both the release of chymase, a neutral protease, from mast cells and the oxidation of HDL by hypochlorous acid can impair the function of phospholipid transfer protein in reverse cholesterol transport. Studies of phospholipid transfer protein-mediated phospholipid transfer activity in humans support a role for phospholipid transfer protein in hypertriglyceridemia, obesity, diabetes, inflammation and coronary artery disease, and in the modulation of LDL particle density and size. Furthermore, recent evidence suggests that phospholipid transfer protein may play a role in reproductive processes, in lipid and lipoprotein metabolism in the central nervous system, and in neurodegenerative disease. SUMMARY: Phospholipid transfer protein is emerging as a multifaceted and multifunctional player in lipid and lipoprotein metabolism, but much additional work will be required to understand the significance of these recent findings for clinical practice.

Animals↗
PubMed1990

Phospholipid specificity of bovine heart bc1 complex.

Bovine heart bc1 complex was reversibly inactivated by a new simple and effective chromatographic delipidation method. Upon phospholipid replenishment, catalytic activity increased from values near zero to values 2-6-times higher than those of the original preparation. Compared to original preparations maximally activated by additional phospholipid, the degree of reactivation was up to 100%. By this delipidation method, the 6.4-kDa protein subunit was removed with the phospholipid. The loss of this protein neither diminished electron transport activity nor abolished proton translocation. Two requirements were necessary to obtain quantitative data: (a) only bc1 complexes, homogeneously dissolved before and after relipidation had to be used and (b) the phospholipid bound to the complex had to be determined. The correlation of catalytic activity to bound phospholipid was studied in the range of low phospholipid/protein ratios, which had previously been insufficiently resolved. Catalytic activity increased linearly with added phospholipid up to a molar ratio of 80-100 lipid molecules/dimeric complex. This corresponds to the number of phospholipid molecules that complete a single bilayer annulus. The activating effect of phospholipid is not merely due to a hydrophobic phase effect, since it strongly depends on the nature of the polar head group of the added phospholipid. Of the three major phospholipids bound to the bc1 complex, only phosphatidylethanolamine and phosphatidylcholine activated when added as sole phospholipid. Tightly bound diphosphatidylglycerol was needed for preservation of the native complex structure.

Animals↗
PubMed1979

Metabolic fate of chylomicron phospholipids and apoproteins in the rat.

To study the metabolic fate of chylomicron phospholipid and apoproteins, 15 mg of doubly labeled ([(3)H]leu, [(32)P]phospholipid) rat mesenteric lymph chylomicrons were injected as an intravenous bolus into conscious rats. The specific radioactivity, composition, pool size, and morphology of the plasma lipoproteins were determined after 2-60 min. After injection of chylomicrons, there was a rapid transfer of radioactivity into high density lipoproteins (HDL). At peak specific activity in HDL (2-5 min), 35% of injected apoprotein and 25% of phospholipid radioactivity were recovered in HDL (d 1.063-1.21 g/ml), with smaller recoveries in other lipoproteins and liver. There was an initial rapid rise of (32)P specific activity in HDL and d 1.02-1.063 lipoproteins (low density lipoproteins [LDL]), but whereas LDL specific activity subsequently converged with that of d < 1.02 lipoproteins, HDL specific activity decayed more rapidly than LDL or d < 1.02 lipoproteins. Lipolysis of chylomicrons was associated with a transfer of phospholipid mass into LDL and HDL. At 5 min, 80% of injected triglyceride had been lipolyzed and there was a significant increase in phospholipid mass in LDL and a smaller increase in HDL. At 10 min, the mass of phospholipid in LDL had returned towards control values, and there was a further increase in phospholipid mass in HDL, which suggested phospholipid transfer from LDL to HDL. In donor lymph chylomicrons (3)H-radioactivity was present in apoprotein (apo)B, apoA-I, and apoA-IV, but only radioactivity of apoA-I and apoA-IV were transferred to HDL. Transfer of radioactivity was associated with loss of mass of apoA-I and apoA-IV from the fraction that contained the chylomicron remnants (d < 1.02). With injection of 15 mg chylomicron, there was a small but insignificant increase in the relatively large pool of HDL apoA-I. However, 60 min after injection of 250 mg of human or rat intestinal chylomicrons into the rat, there was a significant increase in HDL apoA-I that resulted from acquisition of a major fraction of the chylomicron apoA-I. After injection of chylomicrons, phospholipid vesicles were observed by negative stain electron microscopy in the LDL and HDL ultracentrifugal fractions, especially in the LDL. Upon addition of an osmotically active compound, cellobiose, vesicles were observed as flattened particles with a double lipid bilayer thickness ( congruent with 100 A). To validate further the identity of these particles, chylomicrons were injected into rats with [(3)H]glucose, and the recipient rats' plasma was fractionated by chromatography on 6% agarose. Trapping of [(3)H]glucose occurred in the void and LDL regions of the column, and vesicular particles were identified in these column fractions by negative stain electron microscopy. Catabolism of chylomicrons is associated with a rapid transfer of phospholipid, apoA-I, and possibly apoA-IV into HDL. Chylomicron phospholipid appears to give rise to vesicles which are probably incorporated into preexisting HDL. Chylomicron surface components may be an important source of plasma HDL.

Animals↗
PubMed1995

Interspecies comparisons of lens phospholipids.

The purpose of this study was to compare and contrast quantitative crystalline lens phospholipid profiles among human, pig, rabbit, rat mouse, dog, lamb, guinea pig, beef, calf, chinook salmon, and golden roach. Lenses were extracted using chloroform-methanol. The extracts were prepared for phospholipid 31P NMR quantitative analysis using an NMR analytical reagent specifically designed for this purpose. Lens phospholipid profiles vary among vertebrate species. Thirteen different phospholipids [phosphatidylglycerol, lysophosphatidylethanolamine, phosphatidic acid, diphosphatidylglycerol, the ethanolamine plasmalogen (EPLAS), phosphatidylethanolamine (PE), phosphatidylserine (PS), sphingomyelin (SM), lysophosphatidylcholine, phosphatidylcholine (PC), including four uncharacterized (unknown) phospholipids at 1.31 ppm (human), 1.20 ppm (human, rabbit, dog, lamb, beef, calf), 0.13 ppm (all except rat), and -0.17 ppm (rat, beef) were detected. EPLAS, PE, PS, SM, and PC are the major lens phospholipids in all species except the human, where the major phospholipid is the unknown at 0.13 ppm. The lens content of this major unknown in mole percentage of the total detected phospholipid profile is: human 43.7; pig 6.7; rabbit, 6.1; rat (not detected); mouse, 3.2; dog, 5.0; guinea pig, 2.0; lamb, 7.0; beef, 7.7; calf, 5.6; chinook salmon, 6.7; and golden roach, 1.6. Large qualitative and quantitative differences were observed among lens species, indicating the necessity for prudent selection of appropriate animal models. The most striking finding is that no other species except the human species exhibits such a profound amount of the unknown phospholipid at 0.13 ppm. In the human lens, this phospholipid is the major phospholipid.

Animals↗
PubMed1993

The effect of various phospholipids on plasma lipoproteins and liver lipids in hypercholesterolemic rats.

Rats were fed a hypercholesterolemic diet (5% lard, 0.5% cholesterol, and 0.25% sodium cholate) containing 5% of dietary phospholipid as safflower phospholipid (SAP), soybean phospholipid (SOP), or egg yolk phospholipid (EGP), or 5% of soybean oil (SO) as a control for 4 weeks. The concentrations of plasma cholesterol were significantly higher in rats fed the EGP diet than those of the other diets. Similarly, the concentrations of chylomicron plus very low density lipoprotein (VLDL) cholesterol were higher in rats fed the EGP diet. The phospholipid diets induced a significant increase of high density lipoprotein (HDL) cholesterol in comparison with the SO diet. The concentrations of liver cholesterol were significantly lower in rats fed the phospholipid diets than those of the SO diet. Among phospholipid-fed rats, the SAP and SOP diets decreased the concentrations of liver cholesterol compared with the EGP diet. The activity of plasma lecithin-cholesterol acyltransferase (LCAT) was significantly increased in rats fed the phospholipid diets. The phospholipid diets caused an enhanced excretion of neutral steroids into feces. Among phospholipid-fed rats, the SAP and SOP diets increased the excretion of fecal neutral steroids compared with the EGP diet. The fatty acid composition of HDL phospholipid was slightly reflected by the major dietary fat source. These results suggest that SAP and SOP inhibit markedly the absorption of dietary cholesterol in the small intestine of hypercholesterolemic rats and that the effect of SAP and SOP on plasma cholesterol metabolism may be different from that of EGP.

Animals↗
PubMedDate not supplied

[Biological properties of the mechanism of "marine" phospholipids containing omega-3 fatty acids].

The Laboratory mainly deals with the development of biologic technologies for producing physiologically active lipid-protein-nature compounds from marine organisms containing omega-3 fatty acids (that are membrane components) with further evaluation of their action both in the normal state and in some simulated pathologic states as well as with creation of new preparations for application in medicine and agriculture on their basis. As a result of the experiments performed, a technology for producing two biologic preparations, namely, surface active compounds (phospholipids) and a nucleopeptid-lipid complex, exhibiting a specific action, was developed. The phospholipid complex, being surface-active in composition, was characterized as a complex possessing some surfactant-type properties and displaying an antioxidant and a membrane-stabilizing effect. On the basis of the complex including marine phospholipids with omega-3 fatty acids, the preparation "Phylomek", which is the concentrate of essential marine phospholipids, and the preparation "Morephyl", which is a marine agent with surfactant-type effect, intended for animals and poultry, were created. The ingredients of the nucleopeptid-lipid complex were identified, and its effect on the increase of testosterone levels in the blood of old and sick animals was determined. A stimulating agent of genital hormones secretion was recommended for application in the geriatrics in the case of genital function disturbance and presenilation. A fraction similar in chemical content and specific activity, found in the velvet antlers, was used as the base of the biologic preparation "Pantheron". The natural complexes of marine phospholipids were shown to be able to change the composition of lipids of membranes, but the intensity of these changes differed in cells differing in function. In the study of the biochemical mechanism of correction of disturbances in the cell membranes under an oxidative stress, the interrelation between the composition of lipids of membranes, their oxidation, and the content of natural antioxidants was determined. The reparative effect of marine phospholipids on the cell membranes under progressing pathology, caused by the restoration of the composition of phospholipids, by increases in the activities of antioxidant enzymes (SOD, catalase), and by a decrease of the accumulation of LPO products, was established. Under interaction of marine phospholipids and alpha-tocopherol, synergism was noticed, the antioxidant potential of the investigated substances and their membrane-stabilizing effect increased. The phospholipids with various residues of PUFA in the molecule were found to affect the inhibition and oxidation processes, as well as the modelling of lipid membranes. This is especially true for arachidonic and docosahexaenoic acids, the ratio of which changes under the oxidative stress. At administration of phospholipids omega-3, their ratio decreases due a decrease in the level of unetherificated PUFA. The main changes of the PUFA were found to occur in phosphatidylethanolamine isolated from microsomes. The particular role of phosphatidylethanolamine and arachidonic acid in the reparation of membranes under the action of phospholipids PUFA omega-3 and alpha-tocopherol was noted.

Animals↗
PubMed1994

Effect of dietary magnesium deficiency with/without cholesterol supplementation on phospholipid content in liver, plasma and erythrocytes of rabbits.

The effect of magnesium deficiency with/without supplementary cholesterol on phospholipid content in liver, plasma and erythrocytes was investigated in New Zealand White male rabbits. After the rabbits had been fed a low magnesium and/or high cholesterol diet for seven weeks, the phospholipid content in liver, plasma and erythrocytes was measured. Dietary magnesium deficiency produced a marked elevation of total phospholipid and certain individual phospholipids in the rabbit liver. The elevation was accentuated by cholesterol supplementation. In the plasma, a low magnesium intake enhanced plasma phosphatidylcholine, phosphatidic acid, phosphatidylinositol, and sphingomyelin, but an activated conversion from phosphatidylethanolamine to phosphatidylcholine made the increase in phospholipid insignificant. On the other hand, a low magnesium intake restricted the increase in magnitude of phospholipid caused by cholesterol supplementation. In the erythrocytes, total phospholipid, phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine were decreased by a low magnesium and/or a high cholesterol intake. We suggest that the increased contents of total phospholipid and/or certain individual phospholipids in the livers and plasma resulted from the enhanced synthesis of phospholipid in the liver by low magnesium intake. A decreased utilization of food by low magnesium diet limited the magnitude of plasma phospholipid increase produced by cholesterol supplementation.

Animals↗
PubMed2002

A new role for apolipoprotein E: modulating transport of polyunsaturated phospholipid molecular species in synaptic plasma membranes.

Phospholipids and their acyl group composition are important in providing the proper membrane environment for membrane protein structure and function. In particular, the highly unsaturated phospholipids in synaptic plasma membranes in the CNS are known to play an important role in modulating receptor function and neurotransmitter release processes. Apolipoprotein E (apoE) is a major apolipoprotein in the CNS, mediating the transport of cholesterol, phospholipids and their fatty acids, particularly in reparative mechanisms during neuronal injury. This study was performed to determine whether deficiency in the apoE gene contributes to an alteration of the phospholipids in synaptic plasma membranes. Phospholipid molecular species were identified and quantitated by HPLC/electrospray ionization-mass spectrometry. Analysis of the different phospholipid classes in membranes of apoE-deficient and C57BL/6 J mice indicated no obvious differences in the distribution of different phospholipid classes but substantial differences in composition of phospholipid molecular species. Of special interest was the prevalence of phospholipids (phosphatidylcholine, diacyl-phosphatidylethanolamine, and phosphatidylserine) with 22:6n-3 in both the sn-1 and sn-2 positions of SPM and these phospholipid species were significantly higher in apoE-deficient mice as compared to control mice. Since polyunsaturated fatty acids in neurons are mainly supplied by astrocytes, these results revealed a new role for apoE in regulating polyunsaturated phospholipid molecular species in neuronal membranes.

Alzheimer Disease↗
PubMed1996

Metabolism of hydroperoxy-phospholipids in human hepatoma HepG2 cells.

Two enzymatic mechanisms have been proposed for the metabolism of hydroperoxy-phospholipids: i) the combined action of phospholipase A2 and glutathione peroxidase, and/or ii) direct enzymatic reduction. The latter reaction may be catalyzed by selenium-dependent phospholipid hydroperoxide glutathione peroxidase and/or by glutathione S-transferase alpha. To study the pathway of this reaction, we used human hepatoma HepG2 cells into which was incorporated labeled, hydroperoxy-phospholipids. The major product of incorporated l-palmitoyl-2-(13-hydroperoxy-cis-9, trans-11-octadecadienoyl)-L-3-phosphatidylcholine was the corresponding hydroxy-phospholipid with no hydroxy- or hydroperoxy-fatty acids. The contributions to reduction of hydroperoxy-phospholipids in HepG2 cells from glutathione S-transferase Al and phospholipid hydroperoxide glutathione peroxidase were calculated to be 0.5% and 99.5%, respectively. Increasing selenium in the cell culture medium led to increases in selenium-dependent phospholipid hydroperoxide glutathione peroxidase activity but not in glutathione S-transferase alpha. This increase in the selenium-dependent enzyme was paralleled by a concomitant increase in the extent of reduction of the incorporated hydroperoxy-phospholipid. We conclude that the main metabolic fate of hydroperoxy-phospholipids in HepG2 cells is by direct reduction to hydroxy-phospholipids by phospholipid hydroperoxide glutathione peroxidase but also by glutathione S-transferase alpha, and that phospholipase A2/selenium-dependent glutathione peroxidase does not play a significant role in the reduction.

Carcinoma, Hepatocellular↗
PubMed1997

Changes in cellular and plasma membrane phospholipid composition after lipopolysaccharide stimulation of human neutrophils, studied by 31P NMR.

Lipopolysaccharide (endotoxin, LPS) exerts potent proinflammatory effects on neutrophils which may involve membrane phospholipid metabolism. The cellular and plasma membrane phospholipid composition of resting neutrophils and those stimulated with 50 microg ml(-1) LPS were studied by 31P NMR and chemical analysis. A rapid new method for plasma membrane purification was employed, involving the direct lysis of cytoplasts. Chemical analyses showed that, although total cellular phospholipid content did not change with LPS stimulation, there was twice the amount of phospholipid present in plasma membranes isolated from stimulated cells, resulting in a lowered cholesterol/phospholipid ratio. Since internal membranes have lower cholesterol content this result is consistent with an origin from insertion of these membranes (most probably from the endoplasmic reticulum) into the plasma membrane, thereby increasing its fluidity. The individual phospholipid classes of both cells and membranes were quantified by 31P-NMR spectroscopy after dissolution in sodium cholate without prior extraction of lipids, allowing partial resolution of the major phospholipid classes and ether-linked phospholipids. Ether-linked lipids were distinguished from diacyl phospholipids by hydrolysis of lipid extracts with HCl and phospholipase A1, There was a significant increase in phosphatidylserine in both cells and plasma membranes after stimulation, with a decrease in the phosphatidylethanolamine (diacyl and plasmalogen) content in the cells. Plasma membranes from stimulated cells exhibited a significant decrease in a phospholipid tentatively identified as 2-arachidonoyl-1-alkyl-sn-glycero-3-phosphocholine, a precursor of the lipid inflammatory mediator, platelet-activating factor. This report is the first to elaborate the changes in phospholipid composition in human neutrophils as a whole, and in plasma membranes separated from them, before and after stimulation by the physiological activator, LPS.

Cell Compartmentation↗
PubMed2004

Phospholipid transfer protein activity in two cholestatic patients.

CONTEXT: Plasma phospholipid transfer protein mediates the transfer of phospholipids from triglyceride-rich lipoproteins, very low density lipoproteins and low density lipoproteins to high density lipoproteins, a process that is also efficient between high density lipoprotein particles. It promotes a net movement of phospholipids, thereby generating small lipid-poor apolipoprotein AI that contains particles and subfractions that are good acceptors for cell cholesterol efflux. CASE REPORT: We measured the activity of plasma phospholipid transfer protein in two cholestatic patients, assuming that changes in activity would occur in serum that was positive for lipoprotein X. Both patients presented severe hypercholesterolemia, high levels of low density lipoprotein cholesterol and, in one case, low levels of high density lipoprotein cholesterol and high levels of phospholipid serum. The phospholipid transfer activity was close to the lower limit of the reference interval. To our knowledge, this is the first time such results have been presented. We propose that phospholipid transfer protein activity becomes reduced under cholestasis conditions because of changes in the chemical composition of high density lipoproteins, such as an increase in phospholipids content. Also, lipoprotein X, which is rich in phospholipids, could compete with high density lipoproteins as a substrate for phospholipid transfer protein.

Adult↗
PubMed1985

Phospholipid and Ca++ dependency of phorbol ester receptors.

The phospholipid and Ca++ dependency of a partially purified phorbol ester apo-receptor from the soluble fraction of mouse brain homogenates was studied. This apo-receptor is believed to be identical with the Ca++ and phospholipid-dependent protein kinase C. Binding of phorbol esters to the receptor/kinase C was shown to be entirely dependent on phospholipids. The negatively charged phospholipids phosphatidylserine, phosphatidylinositol, and phosphatidic acid all fully reconstituted binding. The neutral phospholipids were inactive. Among active phospholipids and mixtures of phospholipids, substantial differences (greater than 100-fold) were observed in the amounts required to achieve reconstitution. Although Ca++ was not required for reconstitution of binding activity, it dramatically (up to 100-fold) increased the potency of phospholipids for reconstitution. The phospholipids not only permitted reconstitution of the apo-receptor but also played a major role in determining the binding characteristics of the complex. The KD values of [3H]phorbol 12,13-dibutyrate were in the range of 0.8 nM for the complex with phosphatidylserine to 30 nM for the complex with dioleoyl-phosphatidic acid. Like the binding affinity, the stimulation of protein kinase C activity by phorbol esters was dependent on the phospholipid into which the receptor/kinase C was reconstituted. The importance of the lipid domain for controlling the receptor/kinase C activity and for modulation of cellular sensitivity to phorbol esters is discussed.

Animals↗
PubMed2001

Influence of obesity and insulin sensitivity on phospholipid transfer protein activity.

AIMS/HYPOTHESIS: Phospholipid transfer protein plays a key role in lipoprotein metabolism by catalysing the transfer of phospholipids from triglyceride-rich lipoproteins to high-density lipoproteins and, also, within the high-density lipoprotein family, from particle to particle. This transfer results in a change of HDL particle size and the generation of pre-beta-high-density lipoproteins which function as initial lipid acceptors in the process of reverse cholesterol transport. Because adipose tissue is a source of phospholipid transfer protein we investigated the influence of obesity and insulin sensitivity on phospholipid transfer protein activity. METHODS: Using an exogenous substrate assay phospholipid transfer protein activity was measured in plasma specimens of 190 normolipidaemic, non-diabetic subjects with BMI ranging from 19 to 43 kg/m2. Insulin sensitivity was measured by the short insulin tolerance test. RESULTS: Phospholipid transfer protein activity was associated with BMI (r = 0.46, p < 0.01), body fat mass (r = 0.39, p < 0.01), subcutaneous fat area (r = 0.32, p < 0.01) and plasma leptin concentration (r = 0.24, p < 0.01) but not with insulin sensitivity expressed as the k(s) of the insulin tolerance test (kITT value) (r = -0.14, p = 0.40). Accordingly, phospholipid transfer protein activity was higher in obese than in nonobese subjects. As determined by linear regression analysis, BMI was the sole predictor of phospholipid transfer protein activity in plasma explaining 22.2% of the activity (p< 0.01). CONCLUSIONS/INTERPRETATIONS: This data suggests that increased phospholipid transfer protein activity in obese subjects is a consequence of obesity itself without the contribution of insulin resistance and can be explained by increased synthesis of phospholipid transfer protein from the enlarged mass of adipose tissue.

Adipose Tissue↗
PubMed1999

n-3 and n-6 fatty acid enrichment by dietary fish oil and phospholipid sources in brain cortical areas and nonneural tissues of formula-fed piglets.

Sufficient availability of both n-3 and n-6 long-chain polyunsaturated fatty acids (LCPUFA) is required for optimal structural and functional development in infancy. The question has been raised as to whether infant formulae would benefit from enrichment with 20 and 22 carbon fatty acids. To address this issue, we determined the effect of fish oil and phospholipid (LCPUFA) sources on the fatty acid composition of brain cortical areas and nonneural tissues of newborn piglets fed artificially for 2 wk. They were fed sow milk, a control formula, or the formula enriched with n-3 fatty acids from a low-20:5n-3 fish oil added at a high or a low concentration, or the formula enriched with n-3 and n-6 fatty acids from either egg yolk- or pig brain-phospholipids. Both the fish oil- and the phospholipid-enriched formula produced significantly higher plasma phospholipid 22:6n-3 concentrations than did the control formula. The 22:6n-3 levels in the brain, hepatic, and intestinal phospholipids were significantly correlated with plasma values, whereas cardiac 22:6n-3 content appeared to follow a saturable dose-response. Feeding sow milk resulted in a much higher 20:4n-6 content in nonneural tissues than did feeding formula. Supplementation with egg phospholipid increased the 20:4n-6 content in the heart, red blood cells, plasma, and intestine in comparison to the control formula, while pig brain phospholipids exerted this effect in the heart only. The addition of 4.5% fish oil in the formula was associated with a decline in 20:4n-6 in the cortex, cerebellum, heart, liver, and plasma phospholipids, whereas using this source at 1.5% limited the decline to the cerebellum, liver, and plasma. Whatever the dietary treatment, the phosphatidylethanolamine 20:4n-6 level was 10-20% higher in the brain temporal lobe than in the parietal, frontal, and occipital lobes in the temporal lobe by administering the formula enriched with egg or brain phospholipids. In conclusion, feeding egg phospholipids to neonatal pigs increased both the 22:6n-3 content in the brain and the 20:4n-6 content in the temporal lobe cortex. This source also increased the 22:6n-3 levels in nonneural tissues with only minor alterations of 20:4n-6. These data support the notion that infant formulae should be supplemented with both 22:6n-3 and 20:4n-6 rather than with 22:6n-3 alone.

Animals↗
PubMed1989

Quantitative determination of phospholipids using the dyes Victoria blue R and B.

Different phospholipids, except the choline-containing phospholipids phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin, formed complexes with the dye Victoria blue R, which selectively partitioned into the chloroform phase of chloroform/ethylene glycol/glycerol biphasic solvent system, and were quantitatively estimated at 590 nm. Considerable amounts of water, alcohols, nonlipid phosphates, neutral lipids, free fatty acids, and some detergents did not interfere with the formation of phospholipid-dye complexes. This special advantage of the method described allowed combined phospholipid extraction and estimation procedures in one test tube. Because of its high sensitivity (about 24.00 OD units/mumol of phosphatidic acid and about 10.25 OD units/mumol of other phospholipids), specificity, and simplicity, the proposed phospholipid assay appears to be very useful for rapid analyses of lipid extracts as well as TLC spots or suspensions of biological materials, as demonstrated for membranes and cells of Micrococcus lysodeikticus. The applicability of the dye Victoria blue B to the quantitative determination of phospholipids, except phosphatidylcholine, lysophosphatidylcholine, and sphingomyelin, at 605 nm using chloroform/ethylene glycol/glycerol/water and pentane (hexane)/ethyl acetate/isopropanol/water biphasic solvent systems with similar sensitivities and of sodium dodecyl sulfate in the pentane-containing system with high sensitivity (22.96 OD units/mumol) is also shown. The adaptation of this phospholipid assay to the determination of phospholipases C and D and to the differential quantitation of choline-containing phospholipids using additional phospholipid estimation techniques is discussed.

Chloroform↗
PubMed1990

A methodology for determination of phospholipids.

A simple method for the determination of phospholipids in an aqueous dispersion and in amniotic fluid was developed. The procedure is based on the observation that dispersed phospholipids promoted the solubilization of an insoluble dye--detergent complex. The solubilization of the complex between the negatively charged dye, Coomassie brilliant blue (CBB), and a positively charged detergent, cetyltrimethylammonium bromide (CTAB), produced a blue solution having a visible absorbance maximum above 600 nm. A linear increase in absorbance intensity occurs with an increase in phospholipid concentration. An assay using the CBB-CTAB reagent adsorbed on 3-mm glass beads is used to estimate total dispersed phospholipids between 2 and 25 micrograms/ml. Thereby, a two-phase water-methanol-chloroform system is formed. The products of zwitterionic phospholipids (such as phosphatidylcholine and phosphatidylethanolamine) partition to the organic phase while the dye complex solubilized in anionic phospholipids (such as phosphatidylglycerol and phosphatidylinositol) partitions to the aqueous phase. This procedure results in a convenient, sensitive, and rapid method for the simultaneous determination of the total phospholipid, zwitterionic phospholipid, and anionic phospholipid concentrations. Application of the new assay for determination of phospholipids in amniotic fluid is described.

Amniotic Fluid↗
PubMed1985

Phospholipid and detergent effects on (Ca2+ + Mg2+)ATPase purified from human erythrocytes.

(Ca2+ + Mg2+)ATPase (EC 3.6.1.3) was solubilized from human erythrocyte membranes by detergent extraction with Triton N-101 (0.5 mg/mg membrane protein) and purified by calmodulin affinity chromatography. ATPase activity was assayed in mixtures of Triton N-101 and phospholipid, without reconstitution into bilayer vesicles. At low levels of phospholipid (5 micrograms/ml), the ATPase activity was highly sensitive to the detergent concentration, with maximal activity occurring at or near the critical micelle concentration of the detergent. With increased amounts of phospholipid (50 micrograms/ml), detergent concentrations greater than the critical micelle concentration were required for maximal activity. Detergent alone did not support ATPase activity. Sonicated phospholipid in the form of vesicles was equally ineffective. Activity seemed to be dependent on the presence of detergent/phospholipid mixed micelles. The acidic phospholipids, phosphatidylserine and phosphatidylinositol, as well as the commercial phospholipid preparation, Asolectin, gave activities five to eight times greater than the same amount of phosphatidylcholine. Mixtures of phosphatidylserine and phosphatidylcholine produced intermediate ATPase activities, with the maximal value dependent on the phosphatidylserine concentration. Addition of phosphatidylcholine to fixed concentrations of phosphatidylserine caused a rise in activity that was independent of the ratio of the two phospholipids or the total phospholipid concentration. Phosphatidylcholine may therefore be irreplaceable for some aspect of ATPase function. The number of phospholipid molecules present in mixed micelles at maximal ATPase activity was calculated to be near 50. This value implied that the hydrophobic surface of the ATPase molecule must be completely coated by a single layer of phospholipid molecules for maximum activity to occur.

Ca(2+) Mg(2+)-ATPase↗