Supervised exercise training reduces oxidative stress and cardiometabolic risk in adults with type 2 diabetes: a randomized controlled trial

To evaluate the effects of supervised exercise training (SET) on cardiometabolic risk, cardiorespiratory fitness and oxidative stress status in 2 diabetes mellitus (T2DM), twenty male subjects with T2DM were randomly assigned to an intervention group, which performed SET in a hospital-based setting, and to a control group. SET consisted of a 12-month supervised aerobic, resistance and flexibility training. A reference group of ten healthy male subjects was also recruited for baseline evaluation only. Participants underwent medical examination, biochemical analyses and cardiopulmonary exercise testing. Oxidative stress markers (1-palmitoyl-2-[5-oxovaleroyl]-sn-glycero-3-phosphorylcholine [POVPC]; 1-palmitoyl-2-glutaroyl-sn-glycero-3-phosphorylcholine [PGPC]) were measured in plasma and in peripheral blood mononuclear cells. All investigations were carried out at baseline and after 12 months. SET yielded a significant modification (p < 0.05) in the following parameters: V'O₂max (+14.4%), gas exchange threshold (+23.4%), waist circumference (-1.4%), total cholesterol (-14.6%), LDL cholesterol (-20.2%), fasting insulinemia (-48.5%), HOMA-IR (-52.5%), plasma POVPC (-27.9%) and PGPC (-31.6%). After 12 months, the control group presented a V'O₂max and a gas exchange threshold significantly lower than the intervention group. Plasma POVC and PGPC were significantly different from healthy subjects before the intervention, but not after. In conclusion, SET was effective in improving cardiorespiratory fitness, cardiometabolic risk and oxidative stress status in T2DM.

Structural distinction of diacyl-, alkylacyl, and alk-1-enylacyl glycerophosphocholines as [M - 15]⁻ ions by multiple-stage linear ion-trap mass spectrometry with electrospray ionization

We describe a linear ion-trap (LIT) multiple-stage (MS(n)) mass spectrometric approach towards differentiation of alkylacyl, alk-1-enylacyl- and diacyl-glycerophoscholines (PCs) as the [M - 15]⁻ ions desorbed by electrospray ionization (ESI) in the negative-ion mode. The MS⁴ mass spectra of the [M - 15 - R²'CH = CO]⁻ ions originated from the three PC subfamilies are readily distinguishable, resulting in unambiguous distinction of the lipid classes. This method is applied to two alkyl ether rich PC mixtures isolated from murine bone marrow neutrophils and kidney, respectively, to explore its utility in the characterization of complex PC mixture of biological origin, resulting in the realization of the detailed structures of the PC species, including various classes and many minor isobaric isomers.

Supercritical fluid extraction of bacterial and archaeal lipid biomarkers from anaerobically digested sludge

Supercritical fluid extraction (SFE) was used in the analysis of bacterial respiratory quinone (RQ), bacterial phospholipid fatty acid (PLFA), and archaeal phospholipid ether lipid (PLEL) from anaerobically digested sludge. Bacterial RQ were determined using ultra performance liquid chromatography (UPLC). Determination of bacterial PLFA and archaeal PLEL was simultaneously performed using gas chromatography-mass spectrometry (GC-MS). The effects of pressure, temperature, and modifier concentration on the total amounts of RQ, PLFA, and PLEL were investigated by 23 experiments with five settings chosen for each variable. The optimal extraction conditions that were obtained through a multiple-response optimization included a pressure of 23.6 MPa, temperature of 77.6 °C, and 10.6% (v/v) of methanol as the modifier. Thirty nine components of microbial lipid biomarkers were identified in the anaerobically digested sludge. Overall, the SFE method proved to be more effective, rapid, and quantitative for simultaneously extracting bacterial and archaeal lipid biomarkers, compared to conventional organic solvent extraction. This work shows the potential application of SFE as a routine method for the comprehensive analysis of microbial community structures in environmental assessments using the lipid biomarkers profile.

Oxidized phosphatidylcholine is a marker for neuroinflammation in multiple sclerosis brain

Multiple sclerosis (MS) is a common autoimmune neurodegenerative disease of unknown cause, which results in inflammation and plaques of demyelination in brain and eventual axonal degeneration. We report the novel presence of oxidized phosphatidylcholine [1-palmitoyl-2-(5'-oxo)valeryl-sn-glycero-3-phosphorylcholine (POVPC)], a lipid associated with inflammatory diseases such as atherosclerosis and lung disease, in the brain of MS patients. The OxPC epitope was detected by Western blotting with the E06 monoclonal antibody. E06-positive lipid was present in the highest amounts in MS plaques, which also showed evidence of low-molecular-weight (15-kDa) OxPC-modified protein. E06 reactivity did not change with post-mortem interval, and E06-positive lipids were largely absent from control tissue. We then used a second monoclonal antibody (AB1-2, which recognizes the E06/T15 idiotype and therefore detects the presence of antibody to OxPC) to show that MS brain samples were strongly positive for the 50-kDa antibody heavy chain. We also showed that isoelectric focussing of the oligoclonal IgG characteristic of MS revealed some immunoglobulin bands that Western blotted with the AB1-2 antibody. Spinal cords from mice induced to undergo experimental allergic encephalomyelitis (EAE) also showed strong AB1-2 reactivity by both immunocytochemistry and Western blot analysis. We therefore conclude that we can detect both OxPC and 15-kDa protein modified by OxPC and the antibody to the antibody to OxPC (antiidiotype) in pathological tissue and suggest that this could play a role in the progression of MS.

Methane fluxes in permafrost habitats of the Lena Delta: effects of microbial community structure and organic matter quality

For the understanding and assessment of recent and future carbon dynamics of arctic permafrost soils the processes of CH(4) production and oxidation, the community structure and the quality of dissolved organic matter (DOM) were studied in two soils of a polygonal tundra. Activities of methanogens and methanotrophs differed significantly in their rates and distribution patterns among the two investigated profiles. Community structure analysis showed similarities between both soils for ester-linked phospholipid fatty acids (PLFAs) and differences in the fraction of unsaponifiable PLFAs and phospholipid ether lipids. Furthermore, a shift of the overall composition of the microbiota with depth at both sites was indicated by an increasing portion of iso- and anteiso-branched fatty acids related to the amount of straight-chain fatty acids. Although permafrost soils represent a large carbon pool, it was shown that the reduced quality of organic matter leads to a substrate limitation of the microbial metabolism. It can be concluded from our and previous findings first that microbial communities in the active layer of an Arctic polygon tundra are composed by members of all three domains of life, with a total biomass comparable to temperate soil ecosystems, and second that these microorganisms are well adapted to the extreme temperature gradient of their environment.

Dietary gangliosides increase the content and molecular percentage of ether phospholipids containing 20:4n-6 and 22:6n-3 in weanling rat intestine

This study was conducted to determine whether dietary ganglioside (GG) increases the content of ether phospholipids (EPL) in intestinal mucosa. Weanling Sprague-Dawley rats were fed a semipurified diet consisting of 20% fat as a control diet. Two experimental diets were formulated by adding either 0.1% (w/w fat) GGs (GG diet) or 1.0% (w/w fat) sphingomyelin (SM diet) to the control diet. Fatty acid methyl esters from the alkenylacyl, alkylacyl and diacyl subclasses of phospholipids were measured to determine total and molecular percentage of EPL comprising the choline phosphoglyceride (CPG) and ethanolamine phosphoglyceride (EPG) fraction. Animals fed the GG diet significantly increased total EPL content both in CPG (by 36%) and in EPG (by 66%), and the molecular percentage of EPL in CPG (by 76%) and in EPG (by 59%) compared to animals fed the control diet. Dietary GG-induced increase in EPL resulted in a higher level of polyunsaturated fatty acids (PUFA) specifically in 20:4n-6 and 22:6n-3 compared to control animals, leading to a decrease in the ratio of saturated fatty acids (SFA) to PUFA both in CPG and in EPG. Feeding animals the SM diet showed a higher level of EPL than control animals with a concomitant increase in 22:6n-3 in EPL. The present data demonstrate that dietary GG increases the content and composition of EPL containing PUFA in the weanling rat intestine.

Structure of a lactic acid ether-containing and glycerol phosphate-containing O-polysaccharide from Proteus mirabilis O40

An O-polysaccharide was isolated by mild acid hydrolysis from the lipopolysaccharide of Proteus mirabilis O40 and studied by NMR spectroscopy, including 2D 1H, 1H COSY, TOCSY, ROESY, and 1H, 13C HMQC experiments, along with chemical methods. The polysaccharide was found to contain an ether of GlcNAc with lactic acid and glycerol phosphate in the main chain and to have the following structure: --> 3)-beta-D-GlcpNAc4(R-Lac)-(1 --> 3)-alpha-D-Galp-(1 --> 3)-D-Gro-1-P-(O --> 3)-beta-D-GlcpNAc-(1 --> where D-GlcpNAc4(R-Lac) stands for 2-acetamido-4-O-[(R)-1-carboxyethyl]-2-deoxy-D-glucose. This structure is unique among the known structures of the Proteus O-polysaccharides, which is in agreement with the classification of the strain studied into a separate O-serogroup. A serological relatedness of P. mirabilis O40 with some other Proteus strains was revealed and discussed in view of the O-polysaccharide structures.

Phospholipid containing mixed micelles

Mixed micelles of l,2-diheptanoyl-sn-grycero-3-phosphocholine (DHPC) with ionic detergents were prepared to develop well characterized substrates for the study of lipolytic enzymes. The aggregates that formed on mixing DHPC with the anionic surfactant sodium dodecyl sulfate (SDS) and with the positively charged dodecyl trimethylammonium bromide (DTAB) were investigated using time-resolved fluorescence quenching (TRFQ) to determine the aggregation numbers and bimolecular collision rates, and electron spin resonance (ESR) to measure the hydration index and microviscosity of the micelles at the micelle-water interface. Mixed micelles between the phospholipid and each of the detergents formed in all compositions, yielding interfaces with varying charge, hydration, and microviscosity. Both series of micelles were found to be globular up to 0.7 mole fraction of DHPC, while the aggregation numbers varied within the same concentration range of the components less than 15%. Addition of the zwitterionic phospholipid component increased the degree of counterion dissociation as measured by the quenching of the fluorescence of pyrene by the bromide ions bound to DHPC/DTAB micelles, showing that at 0.6 mole fraction of DHPC 80% of the bromide ions are dissociated from the micelles. The interface water concentration decreased significantly on addition of DHPC to each detergent. For combined phospholipid and detergent concentration of 50 mM the interface water concentration decreased, as measured by ESR of the spin-probes, from 38.5 M/L of interface volume in SDS alone to 9 M/L when the phospholipid was present at 0.7 mole fraction. Similar addition of DHPC to DTAB decreased the interfacial water concentration from 27 M/L to 11 M/L. Determination of the physicochemical parameters of the phospholipid containing mixed micelles here presented are likely to provide important insight into the design of assay systems for kinetic studies of phospholipid metabolizing enzymes.

Reinvestigation by phosphorus NMR of lipid distribution in bicelles

Mixtures of dimyristoyl-phosphatidylcholine (DMPC) and dihexanoyl-phosphatidylcholine (DHPC) in water form disks also called bicelles and different bilayer organizations when the mol ratio of the two lipids and the temperature are varied. The spontaneous alignment in a magnetic field of these bilayers above the transition temperature T(m) of DMPC is an attractive property that was successfully used to investigate protein structure by NMR. In this article, we have attempted to give an overview of all structural transformations of DMPC/DHPC mixtures that can be inferred from broad band (31)P-NMR spectroscopy between 5 and 60 degrees C. We show that above a critical temperature, T(v), perforated vesicles progressively replace alignable structures. The holes in these vesicles disappear above a new temperature threshold, T(h). The driving force for these temperature-dependent transformations that has been overlooked in previous studies is the increase of DHPC miscibility in the bilayer domain above T(m). Accordingly, we propose a new model (the "mixed bicelle" model) that emphasizes the consequence of the mixing. This investigation shows that the various structures of DMPC in the presence of increasing mol ratios of the short-chain DHPC is reminiscent of the observation put forward by several laboratories investigating solubilization and reconstitution of biological membranes.

Quantitative determination of the antitumor alkyl ether phospholipid edelfosine by reversed-phase liquid chromatography–electrospray mass spectrometry: application to cell uptake studies and characterization of drug delivery systems

Edelfosine is a synthetic alkyl ether phospholipid that represents a promising class of antitumor agents. However, analytical methods to measure these type compounds are scarce. The lack of a reliable methodology to quantify edelfosine is a major problem in ongoing and scheduled preclinical and clinical trials with this drug. We evaluated the applicability of high-performance liquid chromatography-mass spectrometry to determine edelfosine in biological samples and polymeric delivery systems. Sample pre-treatment involved polymer precipitation or cell lysis with methanol. HPLC separation was performed on an Alltima RPC(18) narrow-bore column and edelfosine quantification was done by electrospray ionization mass spectrometry (ESI-MS) using positive ion mode and selected ion monitoring. Assays were linear in the tested range of 0.3-10 microg/ml. The limit of quantification was 0.3 ng/sample in both matrices, namely biological samples and polymeric delivery systems. The interassay precision ranging from 0.79 to 1.49%, with relative errors of -6.7 and 12.8%. Mean extraction recovery was 95.6%. HPLC-ESI-MS is a reliable system for edelfosine analysis and quantification in samples from different sources, combining advantages of full automation (rapidity, ease of use, no need of extensive extraction procedures) with high analytical performance and throughput.

Ether phospholipids and glycosylinositolphospholipids are not required for amastigote virulence or for inhibition of macrophage activation by Leishmania major

Ether phospholipids are major components of the membranes of humans and Leishmania. In protozoan parasites they occur separately or as part of the glycosylphosphatidylinositol (GPI) anchor of molecules implicated in virulence, such as lipophosphoglycan (LPG), smaller glycosylinositolphospholipids (GIPLs), and GPI-anchored proteins. We generated null mutants of the Leishmania major alkyldihydroxyacetonephosphate synthase (ADS), the first committed step of ether lipid synthesis. Enzymatic analysis and comprehensive mass spectrometric analysis showed that ads1- knock-outs lacked all ether phospholipids, including plasmalogens, LPG, and GIPLs. Leishmania ads1- thus represents the first ether lipid-synthesizing eukaryote for which a completely null mutant could be obtained. Remarkably ads1- grew well and maintained lipid rafts (detergent-resistant membranes). In virulence tests it closely resembled LPG-deficient L. major, including sensitivity to complement and an inability to survive the initial phase of macrophage infection. Likewise it retained the ability to inhibit host cell signaling and to form infectious amastigotes from the few parasites surviving the establishment defect. These findings counter current proposals that GIPLs are required for amastigote survival in the mammalian host or that parasite lyso-alkyl or alkylacyl-GPI anchors are solely responsible for inhibition of macrophage activation.

Biomass measurement of methane forming bacteria in environmental samples

Methane-forming bacteria contain unusual phytanylglycerol ether phospholipids which can be extracted from the bacteria in sediments and assayed quantitatively by high performance liquid chromatography (HPLC). In this procedure the lipids were extracted, the phospholipids recovered, hydrolyzed, purified by thin layer chromatography, derivatized and assayed by HPLC. Ether lipids were recovered quantitatively from Methanobacterium thermoautotrophicum and sediments at levels as low as 8 x 10(-14) moles. In freshwater and marine sediments the flux of methane to the atmosphere and the methane levels in the pore water reflects the recovery of the phytanyl glycerol ether lipid 'signature'. The proportion of the ether phospholipid to the total recoverable phospholipid was highest in anaerobic digester sewage sludge and deeper subsurface freshwater sediment horizons.

Bioactive products of phospholipid oxidation: isolation, identification, measurement and activities

There is considerable evidence to suggest that oxidation of LDL plays an important role in atherogenesis. Polyunsaturated fatty acids, a major oxidative target, are present as phospholipids in the outer core of the lipoprotein particle. Studies from several laboratories have shown an increase in the levels of phospholipid oxidation products in atherosclerotic lesions and of antibodies to oxidized phospholipids in mice and humans with lesions. Significantly, phospholipid oxidation products have been demonstrated (in vitro) to selectively activate processes in vascular wall cells that may contribute to atherogenesis. This review discusses activities, methods for isolation, identification and measurement of bioactive phospholipids. Past studies suggest that defined and relatively simple current technologies allow identification of bioactive phospholipid oxidation products and measurement of their levels in tissue.

Identification and pharmacological characterization of platelet-activating factor and related 1-palmitoyl species in human inflammatory blistering diseases

Through its pro-inflammatory effects on leukocytes, endothelial cells, and keratinocytes, the lipid mediator platelet-activating factor (PAF) has been implicated in cutaneous inflammation. Although the 1-alkyl PAF species has been considered historically the most abundant and important ligand for the PAF receptor (PAF-R), other putative ligands for this receptor have been described including 1-acyl analogs of sn-2 acetyl glycerophosphocholines. Previous bioassays have demonstrated a PAF-like activity in lesions of the autoimmune blistering disease bullous pemphigoid. To assess the actual sn-2 acetyl glycerophosphocholine species that result in this PAF agonistic activity, we measured PAF and related sn-2 acetyl GPCs in fresh blister fluid samples from bullous pemphigoid and noninflammatory (suction-induced) bullae by mass spectrometry. We report the presence of 1-hexadecyl as well as the 1-acyl PAF analog 1-palmitoyl-2-acetyl glycerophosphocholine (PAPC) in inflammatory blister fluid samples. Because PAPC is the most abundant sn-2 acetyl glycerophosphocholine species found in all samples examined, the pharmacological effects of this species with respect to the PAF-R were determined using a model system created by transduction of a PAF-R-negative epidermoid cell line with the PAF-R. Radioligand binding and intracellular calcium mobilization studies indicated that PAPC is approximately 100x less potent than PAF. Though a weak agonist, PAPC could induce PAF biosynthesis and PAF-R desensitization. Finally, intradermal injections of PAF and PAPC into the ventral ears of rats demonstrated that PAPC was 100x less potent in vivo. These studies suggest possible involvement of PAF and related species in inflammatory bullous diseases.

Determination of 1-O-acyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, platelet-activating factor and related phospholipids in biological samples by high-performance liquid chromatography--tandem mass spectrometry

Combining normal-phase HPLC separation and tandem mass spectrometric detection, using an ion-spray HPLC-MS interface, a quantitative method for acyl-platelet activating factor (acyl-PAF), platelet-activating factor (PAF) and related phospholipids was developed. Mass spectra, positive ions, showed intense [M+H]+ ions; collision-induced dissociation of protonated molecular ions gave characteristic daughter ions corresponding to the polar head. Detection limits of 0.1-0.3 ng injected were obtained by multiple reaction monitoring. Samples of human endothelial cells treated with compounds modulating the levels of acyl-PAF and PAF have been analyzed by the present technique, proving that this approach is suitable for biochemical studies.

Measurement of phospholipase A2 and 1-alkylglycerophosphocholine acetyltransferase activities in stimulated alveolar macrophages by HPLC analysis of NBD-labeled ether lipids

The importance of phospholipases in cellular signaling and 1-alkylglycerophosphocholine acetyltransferase in the formation of platelet-activating factor (PAF) has stimulated demand for methods to measure these enzyme activities in inflammatory cells. Most of the assays currently used rely on radiolabeled substrates. We have synthesized NBD-labeled ether lipids as substrates for measuring enzyme activities of the PAF cycle and of lysosomal phospholipase A2 (PLA2). The fluorescent lipids were incubated with homogenates of stimulated bovine alveolar macrophages. The generated products were separated from the substrates by HPLC on a normal phase and monitored with a fluorescence detector. NBD-lyso-PAF was well accepted by acetyl- and acyltransferases of the cell-free preparations, which metabolized the substrate into NBD-PAF and NBD-alkyl-acylglycerophosphocholines. Homogenates of stimulated cells showed an enhanced production of NBD-PAF. The increased formation of the biological mediator was dependent on the nature of the stimuli and the time of stimulation. Lysosomal PLA2 was measured with 1-O-(12-NBD-aminododecyl)-2-acyl-sn-glycero-3-phosphocholine as substrate. By varying the pH and the calcium concentration, it was possible to distinguish between the cytosolic PLA2 and the lysosomal PLA2 activity. Optimal conditions for the determination of the lysosomal PLA2 were obtained at pH 4.5 and in the presence of EDTA. Stimulation with particulate agonists induced an enhancement of the lysosomal PLA2 activity in macrophages.

Capillary gas chromatography of hexadecylphosphocholine in Caco-2T cells and cell culture media

The gas-chromatographic determination of hexadecylphosphocholine (HePC), an experimental antitumor agent of the alkyllysophospholipid group, in Caco-2T cell culture and cell culture media is described. The Caco-2T cells were treated with HePC at a concentration of 40 micrograms/ml (9.8 microM) and the uptake of the drug into the cells (calculated per milligram protein) was measured after 48 h culture (37 degrees C, 10% CO2). Also, a reversibility test for another 48 h was carried out in which the retention of the drug was measured. The toxicity of HePC on Caco-2T cells in viability assays was determined. Before the capillary gas-chromatographic determination, sample cleanup was performed by solid-phase extraction (SPE) on a weak cation-exchange column of the CBA (carboxylic acid) type. For quantitation, racemic 1-O-octadecyl-2-O-methylglycero-3-phosphorylcholine (ET-18-OMe) was added as internal standard, followed by derivatization with trimethylsilylbromide. The results showed that HePC taken up by the cells during 48 h of treatment was still detectable 48 h after removal of the drug from the medium.

Isoprenoid-mediated changes in the glycerophospholipid molecular species of the sterol auxotrophic fungus Lagenidium giganteum

The mosquito pathogenic fungus Lagenidium giganteum (Oomycetes: Lagenidiales) is a sterol auxotroph that can grow vegetatively in the absence of these compounds, but requires an exogenous source of sterols to enter its sexual and asexual reproductive cycles. Electrospray mass spectrometry (MS) and electrospray MS/MS were used to examine three major glycerophospholipid molecular species--glycerophosphocholine (GPC), glycerophosphoethanolamine (GPE) and glycerophosphoinositol (GPI)--from fungal mycelium and nuclei grown in defined medium with and without isoprenoids which induce (cholesterol and ergosterol) or do not induce (squalene, cholestane) reproduction. Testosterone supplementation of defined media inhibited growth of L. giganteum, so the effect of this steroid on phospholipid metabolism could not be assessed. Mycelium grown in defined media supplemented with these isoprenoids produced significantly different quantities of total phospholipid relative to unsupplemented media and to each other, ranging from a mean of 292 micrograms phosphate per g wet weight for cholesterol-supplemented media to 56 micrograms phosphate per g wet weight for mycelium grown in the presence of squalene. A very large percentage of the GPC (69-80 mol%) and GPI (74-79 mol%) molecular species from mycelia and nuclei contained ether linkages. GPE molecular species had 13-20 mol% ether-containing moieties. The elevated levels of ether lipids may be related to the sterol auxotrophic nature of the fungus. Isoprenoid supplementation of defined growth media resulted in many significant changes in molecular species for all three lipid classes. Significant differences (P < 0.05) in the percentage of total cell ether lipids in GPC and GPE were generated by isoprenoid supplements to culture media. Mycelium grown in the presence of the two sterols which induce asexual and sexual reproduction in L. giganteum, cholesterol and ergosterol, had a significantly greater percentage of ether-containing GPE moieties. The glycerolipid species from nuclei isolated from cultures grown with cholesterol and ergosterol were similar to the composition of nuclei isolated from fungus cultured in defined medium without any supplement or supplemented with squalene. The nuclear membrane from mycelia grown in cholestane-supplemented media, however, had a very different glycerophospholipid composition relative to either whole cells or nuclei from cells grown on other media. It appears that one of the reasons that cyclic isoprenoids such as cholestane do not induce fungal reproduction is that they drastically alter the nuclear membrane glycerophospholipid composition.

Two new phospholipids, hydroxyarchaetidylglycerol and hydroxyarchaetidylethanolamine, from the Archaea Methanosarcina barkeri

The structures of two new ether phospholipids of the methanogenic Archaea, Methanosarcina barkeri, were determined as hydroxyarchaetidylglycerol and hydroxyarchaetidylethanolamine by means of chemical, chromatographic and enzymatic analyses, and fast atom bombardment-mass spectrometry. These lipids are hydroxy diether analogs of phosphatidylglycerol and phosphatidylethanolamine, respectively, with beta-hydroxyarachaeol (2-O-(3'-hydroxy)phytanyl-3-O-phytanyl-sn-glycerol) as a core lipid. In addition, two other ether phospholipids, usual archaetidylglycerol and archaetidylethanolamine, were also identified in the organism. The stereochemical structure of the unalkylated glycerophosphate of hydroxyarchaetidylglycerol and archaetidylglycerol was determined as sn-glycerol-3-phosphate by use of sn-glycerol-3-phosphate dehydrogenase. The stereochemical configuration of the glycerophosphoglycerol backbone of these lipids was a mirror image of that of diacylphosphatidylglycerol from the organisms of the domains Bacteria and Eucarya, and it was shared with extremely halophilic Archaea. These four phospholipids, in addition to five lipids that had already been reported, accounted for 88% of the total polar lipids of this organism.

Gas chromatographic determination of alkyl lysophospholipids after solid-phase extraction from cell culture media

The gas chromatographic determination of 1-O-octadecyl-2-O-methyl-DL-glycero-3-phosphorylcholine (Et-18-OMe), an anti-invasive alkyl lysophospholipid, in cell culture media is described. Sample clean-up was performed by solid-phase extraction on a weak cation-exchange column of the CBA type (carboxylic acid). For quantitation, the structural analogue Et-16-OMe as the internal standard was used after derivatization with trimethylsilyl bromide. The described method was free of interferences in cell culture media. The overall precision for twenty determinations was 14.99%.

Diphytanyl glycerol ether distributions in sediments of the Orca Basin

Archaebacterially produced diphytanyl glycerol ether (DPGE) was examined in core sediments from the Orca Basin, an anoxic hypersaline basin in the northwestern Gulf of Mexico, to observe its spatial variability and potential origin. A differential extraction protocol was employed to quantify the isopranyl glycerol ethers associated with unbound, intermediate-bound, and kerogen-bound lipid fractions. Archaebacterial lipids were evident at all depths for the unbound and intermediate-bound fractions. Concentrations of DPGE ranged from 0.51 to 2.91 micrograms/g dry sediment at the surface and showed secondary maxima deeper in basin sediments. Intermediate-bound DPGE concentrations exhibited an inverse relationship to unbound DPGE concentrations. Kerogen-bound DPGE concentrations were normally below detection limits. Earlier studies describing the general homogeneity of lipid components within the overlying brine and at the brine/seawater interface suggest that the large-scale sedimentary DPGE variations observed in this study result from spatial and temporal variations in in situ production by methanogenic or extremely halophilic archaebacteria.

Distribution of alkyl and alkenyl ether-linked phospholipids and platelet-activating factor-like lipid in various species of invertebrates

The levels of alkenylacyl, alkylacyl and diacyl subclasses of choline glycerophospholipid (CGP) and ethanolamine glycerophospholipid (EGP) fractions in 28 species of various invertebrates were studied. We found that only small amounts of either 1-alkyl-2-acyl-sn-glycero-3-phosphocholine (alkylacyl-GPC) or 1-alkenyl-2-acyl-sn-glycero-3-phosphoethanolamine (alkenylacyl-GPE) are present in most species of insects. On the other hand, almost all species examined in various phyla other than Arthropoda were shown to contain large amounts of both alkylacyl-GPC and alkenylacyl-GPE. The highest proportion of alkylacyl subclass in CGP was noted in sponge, Halichondria japonica (81.8% of CGP) and the highest proportion of alkenylacyl subclass in EGP was found in clam worm, Marphysa sanguinea (88.7% of EGP). We next surveyed the presence of platelet-activating factor (PAF)-like lipid in 45 species of invertebrates. PAF-like lipid was widely distributed among various lower animals. The highest value was obtained for sea cucumber, Stichopus japonicus, in which PAF-like lipid was present throughout the body. We also confirmed the presence of acetyltransferase activity in several lower animals. These results suggest that alkyl and alkenyl ether-linked phospholipids including PAF are physiologically important molecules particularly for invertebrates belonging to lower phyla.

Ether-linked phosphoglyceride content of human leukemia cells

The glycerolipids of most cells are characterized by a specific proportion of ether linkages at the sn-1 position of the glycerol backbone. A number of tumors are known to have altered concentrations of ether-linked lipids compared to normal tissues. However, no through examination of the ether-lipid content of human leukemia cells has been reported despite the importance of these lipids in normal leukocyte function. In the present study samples were obtained from adults with acute myelogenous leukemia (AML), chronic granulocytic leukemia in blast crisis, and acute lymphocytic leukemia and from healthy human donors. The cellular lipids were extracted, the individual phospholipid classes were isolated, lipid phosphorus content was determined, and the lipids were converted to diglyceride benzoate derivatives for separation and quantitation of the subclasses by high performance liquid chromatography. The data indicate that all the leukemic cells analyzed have an altered phospholipid composition compared to their respective normal leukocytes. Furthermore, among the AML patients both the percentage of the choline-containing phosphoglyceride fraction (PC) which is alkyl linked and the nmoles alkyl-PC/10(6) cells differ significantly by FAB subtype. A positive correlation between the levels of alkyl-PC and the degree of cellular differentiation is observed. Although no differences are observed between chronic granulocytic leukemia in blast crisis and AML lipids, the leukemic cells contain dramatically lower levels of alkyl-linked PC than do normal polymorphonuclear leukocytes. In contrast, no differences are observed between the alkyl-PC content of normal and leukemic lymphocytes. In light of the relations among ether-lipids, protein kinase C, and cell differentiation, these data suggest the ether-linked lipids are important in myeloid cell function and differentiation.

Composition of mouse peritoneal macrophage phospholipid molecular species

The individual molecular species composition of diacyl, alkylacyl and alkenylacyl glycerophospholipids was determined in mouse peritoneal macrophages. A marked heterogeneity in the relative composition (mol%) of macrophage ether and ester phospholipid individual species was noted. High concentrations of 16:0-20:4 were found in ether phospholipids such as alkenylacyl glycerophosphoethanolamine (GPE; 27.5 mol%) and alkylacyl glycerophosphocholine (GPC; 16.6%) as compared to mol% levels of 16:0-20:4 in diacyl GPE (5.7%) and diacyl GPC (8.1%), respectively. Interestingly, alkenylacyl GPE was highly enriched in 1-ether (16:0) relative to alkylacyl GPC. The predominant diacyl molecular species in glycerophosphoinositol (GPI) and glycerophosphoserine (GPS) were 18:0-20:4 (59.1%) and 16:0-18:1 (41.1%), respectively. It is noteworthy that the level of 18:0-20:4 was several times higher in diacyl GPI (59.1%) than in diacyl GPS (11.1%), diacyl GPE (25.7%), and diacyl GPC (3.7%). The most abundant molecular species in diacyl GPC and diacyl GPE were 16:0-18:1 (29.9%) and 18:0-20:4 (25.7%), respectively. The abundance of 20:4 in ether phospholipids, specifically 16:0-20:4 and 18:0-20:4, in alkylacyl GPC is significant in view of the role these antecedents play in the biosynthesis of platelet-activating factor (PAF) and 20:4-derived eicosanoids in stimulated macrophages. The unique molecular species composition of the peritoneal macrophage distinguishes this cell type from others.

Simple method for the analysis of glycerol enol ethers derived from plasmalogens in complex lipid mixtures and subsequent determination of the aldehydic components by gas chromatography-mass spectrometry

Glycerol enol ethers, obtained by the reduction of plasmalogens with lithium aluminum hydride, can be converted into glycerol alk-(1)-enyl ether bismethyl ethers with diazomethane in the presence of silica gel. Their mass spectra allow the position of the enol ether group in glycerol unit to be deduced. Branches in the aldehydic components of the glycerol alk-(1)-enyl ether bismethyl ethers can be identified unequivocally by preparation of the 2-alkyl-1,3-dithiolanes, desulphurization with Raney nickel and deuterium to hydrocarbons and subsequent analysis by gas chromatography-mass spectrometry.

Determination of a platelet activating factor antagonist (CV-3988): methodology and clinical application

A high-performance liquid chromatographic method was developed for determination of the platelet activating factor antagonist CV-3988 in human plasma and urine. After development of a column extraction procedure without an internal standard, a more satisfactory organic extraction procedure was set up with amiodarone as internal standard. Linearity of the calibration curves was found in the range 0.0625-10 micrograms/ml CV-3988. Reproducibility was higher than 10% for the column extraction and lower than 10% for the organic extraction procedure. Recovery of CV-3988 from plasma averaged 81.7% for the column procedure and 40% for the organic extraction. Urine samples could be extracted only by the organic extraction procedure. The organic extraction procedure was applied to the determination of CV-3988 in plasma and urine samples after intravenous administration to normal volunteers.

Nonelectrolyte permeability of liposomes of hydroxyfatty acid-containing phosphatidylcholines

Two phosphatidylcholines containing hydroxylated fatty acids, 1-palmitoyl-2-[5-hydroxy-6,8,11,14-eicosatetraenoyl]-sn-glycero-3- phosphocholine (1-palm-2-5HETE PC) and 1-palmitoyl-2-[15(S)-hydroxy-5,8,11,13- eicosatetraenoyl]-sn-glycero-3-phosphocholine (1-palm-2-15HETE PC), and one phosphatidylcholine containing nonhydroxylated fatty acids, 1-palmitoyl-2-arachidonyl-sn-glycero-3-phosphocholine (1-palm-2-arach PC) were synthesized. Permeation of small nonelectrolytes (glycerol, 1,2-propanediol, urea, methylurea, propionamide and dimethylformamide) was assessed in multilamellar liposomes containing these synthetic PCs plus egg yolk phosphatidycholine (EPC) in the presence and absence of cholesterol. In liposomes containing 23% cholesterol, 69.3% EPC and 7.7% of either 1-palm-2-5HETE PC or 1-palm-2-15HETE PC the permeability to small nonelectrolytes was 60 to 400% greater than in liposomes containing 23% cholesterol and 77% EPC. The HETE-containing PCs also increased permeability in liposomes without cholesterol but the effects were less striking. Addition of the synthetic PCs did not affect the energy of activation of permeation.

Correlation of ether lipid content of human leukemia cell lines and their susceptibility to 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine

A number of synthetic ether-linked phospholipids are selectively cytotoxic to neoplastic cells. However, the mechanisms underlying this selective cytotoxicity are not known. We have investigated the ether-lipid content of HL-60 and K562 human leukemia cells in relation to their sensitivity to 1-O-alkyl-2-O-methyl-rac-glycero-3-phosphocholine (ET-18-OCH3). HL-60 cells are much more sensitive than K562 cells to the cytotoxic effects of ET-18-OCH3 and, at the same time, they contain nearly twice as much ether lipid as the more resistant K562 cells. These observations suggested a relation between the cellular ether-lipid content and sensitivity to ET-18-OCH3. Further evidence linking these properties was obtained when the ether-lipid content of K562 cells was increased by incubating them in medium containing 1-O-hexadecyl-sn-glycerol. This supplementation not only increased the ether-lipid content of the cells but also increased their sensitivity to ET-18-OCH3. The 50% inhibitory concentration for ET-18-OCH3 decreased from 18.4 microM in the control cells to 9.83 microM in the supplemented cells.

Di-O-alkylglycerol, mono-O-alkylglycerol and ceramide inositol phosphates of Leishmania mexicana mexicana promastigotes

Three acidic unsaponifiable lipid fractions were isolated by chromatographic methods from sandfly vector stages (promastigotes) of a protozoan parasite of man, Leishmania mexicana mexicana, cultured in vitro. Fast atom bombardment mass spectrometry, fast atom bombardment collision induced tandem mass spectrometry and metabolic labeling were used to characterize these lipids as di-O-alkylphosphatidyl-inositols, lyso-1-O-alkylphosphatidylinositols and inositol phosphosphingolipids. Molecular species of the dialkyl forms, new to natural product biochemistry, had a 20:0 substituent and either 17:1 or 18:1. The monoalkyl forms had either 17:0 or 18:0. The predominant ceramide had the 16:1 base and the lesser component the 16:0 base. In both, the N-acyl group was 18:0.

Evidence that the endogenous heat-stable glucocorticoid receptor stabilizing factor is a metal component of the untransformed receptor complex

Boiled cytosols prepared from a wide variety of sources contain a low Mr factor that inhibits glucocorticoid receptor transformation to the DNA-binding state (Leach, K.L., Grippo, J.F., Housley, P.R., Dahmer, M.K., Salive, M.E., and Pratt, W.B. (1982) J. Biol. Chem. 257, 381-388). In this work, we show that this endogenous factor, which is partially purified from rat liver, produces all of the effects of the group VI-A transition metal oxyanions molybdate and vanadate on the structure and function of glucocorticoid receptors in cytosol preparations. Like molybdate, the endogenous factor behaves as a strong anion with an apparent Mr of 340 on Bio-Gel P-2, and it binds to both hydroxylapatite and Chelex 100 resins. The receptor stabilizing activity of the factor is completely stable to heating at 320 degrees C for 1 h. The small size, profound heat stability, and absorption by a metal chelating resin strongly suggest that the factor is an endogenous metal anion. As reduction of the concentration of the factor in cytosol promotes generation of the DNA-binding form of the receptor, we suggest that this endogenous metal anion interacts with the receptor to stabilize the 9 S complex and maintain the receptor in its untransformed, non-DNA-binding state. We propose that molybdate and vanadate may exert their effects on the untransformed receptor by interacting with the binding site for the endogenous metal anion.

Quantitative conversion of diether or tetraether phospholipids to glycerophosphoesters by dealkylation with boron trichloride: a tool for structural analysis of archaebacterial lipids

A method for preparing glycerophosphoesters from ether phospholipids by dealkylation with boron trichloride (BCl3) is described. Treatment of ether phospholipids in chloroform with BCl3 for 30 min at room temperature yielded almost quantitatively the corresponding glycerophosphoesters retaining the intact polar head group of the ether phospholipids. Thus, glycerophosphocholine, glycerophosphoinositol, glycerophosphoglycerol, glycerophosphoserine, glycerophosphate, and glycerophosphoethanolamine were prepared from the diether analogs of phosphatidylcholine, phosphatidylinositol, phosphatidylglycerol, phosphatidylserine, and phosphatidic acid, and the tetraether analog of phosphatidylethanolamine, respectively. BCl3 also cleaved diacyl, alkyl-acyl, and alk-1-enyl-acyl forms of phospholipids to yield corresponding glycerophosphoesters. The glycerophosphoesters were separated more rapidly by cellulose thin-layer chromatography with the same solvent system as in paper chromatography. This method is of great use for structure determination of glycerophosphoester backbones of ether phospholipids, analogous to the mild alkaline methanolysis of diacyl form of phospholipids, as well as for the analysis of alkyl chains. It is, however, not applicable to glycolipids because of cleavage of glycosidic bonds by BCl3.