Mechanism of lysophosphatidylcholine accumulation in the ischemic canine heart

The metabolism of lysophosphatidylcholine (LPC) in non-ischemic and ischemic canine heart was investigated byin vitro enzyme analysis. Selected subcellular fractions were assayed for the LPC-producing enzyme phospholipase A and the LPC-eliminating enzymes LPC:acyl-CoA acyltransferase, LPC:LPC transacylase and lysophospholipase. The canine heart was found to contain all enzymes differing, however, in subcellular distribution and specific activity. Phospholipase A activity did not change significantly in any of the fractions prepared from the ischemic tissue of hearts rendered ischemic for 1, 3 or 5 hr when compared to non-ischemic tissue. Changes in the activity of the microsomal LPC:acyl-CoA acyltransferase over the course of 5 hr of ischemia were observed. Significant decreases in the activity of the cytosolic and microsomal lysophospholipases were detected especially after 3 and 5 hr of ischemia. Similarly, a decrease in the activity of the microsomal LPC:LPC transacylase was noted after 3 and 5 hr of ischemia. Our results suggest that impaired catabolism of LPC rather than an enhanced production of LPC is the principal mechanism for the increase in LPC levels in the ischemic canine heart.     

Alterations of phospholipids in ischemic canine myocardium during acute arrhythmia

Myocardial ischemia was produced in the left ventricle of the canine heart by a Harris two-stage occlusion of the left anterior descending coronary artery. The lipid content in the ischemic myocardium was analyzed and compared with the control tissue. No significant change in total phospholipid and cholesterol was detected. A 2-fold elevation in the levels of the major lysophospholipids was observed during acute ventricular arrhythmias at 24hr after the onset of ischemia. Such increases were not caused by preferential hydrolysis of phospholipid plasmalogens from the parent phospholipids.     

Enrichment of Lysophosphatidylcholine in Canola Lysolecithin

Lysophosphatidylcholine (LPC) possesses excellent oil‐in‐water emulsifying properties and health benefits. The objective of this study was to produce an LPC‐enriched fraction from lysolecithin generated during enzymatic degumming of crude canola oil. Three alcohols (methanol, ethanol and isopropanol) were evaluated for their effectiveness at enriching LPC. A 3 × 3 full factorial design was employed to study the effects of two processing parameters (temperature and alcohol/lysolecithin ratio) on three responses (yield and LPC concentration of alcohol soluble fraction, and LPC recovery) with the most effective alcohol. Ethanol was found to be the best solvent to enrich LPC in lysolecithin. An ethanol soluble fraction with more than 50 % LPC was produced. Quadratic models with R² > 0.9 were developed to describe the relationship between the processing parameters and the responses in the 3 × 3 full factorial experiment. Both ethanol soluble fraction yield and LPC recovery increased with increasing temperature and ethanol/lysolecithin ratio. LPC concentration in the ethanol soluble fraction was enhanced with decreasing temperature and ethanol/lysolecithin ratio. According to the analysis, ethanol soluble fractions with LPC concentration higher than 66 % could be obtained at temperatures of 0–40 °C and an ethanol/lysolecithin ratio of 2:1 (v/w).     

Organ-Specific Distributions of Lysophosphatidylcholine and Triacylglycerol in Mouse Embryo

Imaging mass spectrometry (IMS) has been developed as a method for determining and visualizing the distribution of proteins and lipids across sections of dissected tissue. Although lipids play an important role in mammal development, their detailed distributions have not been analyzed by conventional methods. In this study, we tried to determine and visualize lysophosphatidylcholine (LysoPtdCho) and triacylglycerol (TAG) in a mouse embryo by matrix-assisted laser desorption/ionization (MALDI) hybrid quadrupole time-of-flight (TOF) mass spectrometer. Many peaks were detected from a raster scan of the whole embryonic sections. The peaks at m/z 496.33, 524.36, 879.72, 881.74, and 921.74 were identified by MS/MS analyses as [LysoPtdCho (16:0) + H]⁺, [LysoPtdCho (18:0) + H]⁺, [TAG (16:0/18:2/18:1) + Na]⁺, [TAG (16:0/18:1/18:1) + Na]⁺, and [TAG (16:0/20:3/18:1) + K]⁺, respectively. The ion images constructed from the peaks revealed that LysoPtdCho were distributed throughout the body and TAGs were distributed around the brown adipose tissue and in the liver at embryo day 17.5. Thus, IMS system based on MALDI hybrid quadrupole TOF MS revealed the distribution of LysoPtdCho and, more importantly, the organ-specific distribution of TAGs in the embryonic stages of mammals for the first time. We can conclude that this technique enables us to analyze the roles of various lipids during embryogenesis and gives insight for lipid research.     

Substrate Preferences of a Lysophosphatidylcholine Acyltransferase Highlight Its Role in Phospholipid Remodeling

An important enzyme involved in phospholipid turnover is the acyl-CoA: lysophosphatidylcholine acyltransferase (LPCAT). Here, we report characterization of a newly discovered human LPCAT (LPCAT3), which has distinct substrate preferences strikingly consistent with a role in phosphatidylcholine (PtdCho) remodeling and modulating fatty acid composition of PtdCho. LPCAT3 prefers lysophosphatidylcholine (lysoPtdCho) with saturated fatty acid at the sn-1 position and exhibits acyl donor preference towards linoleoyl-CoA and arachidonoyl-CoA. Furthermore, LPCAT3 is active in mediating 1-O-alkyl-sn-glycero-3-phosphocholine acylation with long chain fatty acyl-CoAs to generate 1-O-alkyl-phosphatidylcholine, another very important constitute of mammalian membrane systems. These properties are precisely the known attributes of LPCAT previously ascribed to the isoform involved in Lands' cycle, and thus strongly suggest that LPCAT3 is involved in phospholipids remodeling to achieve appropriate membrane lipid fatty acid composition.     

Phospholipidomic Analysis Reveals Changes in Sphingomyelin and Lysophosphatidylcholine Profiles in Plasma from Patients with Neuroborreliosis

In recent years, the number of patients suffering from Lyme Disease (LD) has significantly increased. The most dangerous manifestation of LD is neuroborreliosis associated with invasion of the central nervous system by Borrelia burgdorferi. Phospholipids (PL) and their metabolites are involved in inflammation, which plays a dominant, but still unclear, role in the pathogenesis of neuroborreliosis. We analyzed the plasma PL profiles of neuroborreliosis patients (n = 8) and healthy volunteers (n = 8) using a lipidomic approach. Significant increases in the lysophosphatidylcholines LysoPtdCho 16:0 and LysoPtdCho 18:2 were observed. The plasma of neuroborreliosis patients appeared to have an increased relative abundance of sphingomyelin CerPCho d18:1/24:1 and a decrease in CerPCho d18:0/18:0. Principal components analysis of the relative abundances of all PL class species distinguished between neuroborreliosis patients and healthy subjects. This is the first report comparing PL classes and their molecular species in neuroborreliosis patients and healthy subjects.     

Lysophosphatidylcholine Exhibits Selective Cytotoxicity,Accompanied by ROS Formation,in RAW 264.7 Macrophages

Lysophosphatidylcholine (lysoPtdCho) is a component of oxidized low density lipoprotein, and is involved in the pathogenesis of atherosclerosis and inflammation. We studied the effects of lysoPtdCho on cytotoxicity, reactive oxygen species (ROS) production, activation of the extracellular signal-regulated kinase (ERK), mitogen-activated protein kinases and pro-inflammatory gene expression in RAW 264.7 murine macrophage cells. When cells were exposed to lysoPtdCho with various acyl chains in a culture medium containing 10% fetal bovine serum, only 1-linoleoyl (C18:2) lysoPtdCho showed a remarkable cytotoxicity, reaching the highest level at 24 h, and elicited ROS production, suggesting that oxidative stress might be implicated in the cytotoxicity of 1-linoleoyl (C18:2) lysoPtdCho. Presumably in support of this, antioxidants such as magnolol or trolox prevented 1-linoleoyl (C18:2) lysoPtdCho-induced cytotoxicity as well as ROS production, although only partially. Furthermore, the phosphorylation of ERK 1/2 and the expression of pro-inflammatory cytokines such as IL-1β, CCL2 and CCL5 were augmented by 1-linoleoyl (C18:2) lysoPtdCho. Meanwhile, there was no structural importance of the acyl chain for the cytotoxic action of lysoPtdCho during 10 min incubation in serum-free media. Taken together, it is suggested that in a serum-containing medium, 1-linoleoyl (C18:2) lysoPtdCho can cause a significant cytotoxicity through ROS production, probably accompanied by activation of ERK and induction of related inflammatory cytokines, in RAW 264.7 cells.     

Low erucic acid canola oil does not induce heart triglyceride accumulation in neonatal pigs fed formula

Canola oil is not approved for use in infant formula largely because of concerns over possible accumulation of triglyceride in heart as a result of the small amounts of erucic acid (22∶1n−9) in the oil. Therefore, the concentration and composition of heart triglyceride were determined in piglets fed from birth for 10 (n=4–6) or 18 (n=6) d with formula containing about 50% energy fat as 100% canola oil (0.5% 22∶1n−9) or 100% soybean oil, or 26% canola oil or soy oil (blend) with palm, high-oleic sunflower and coconut oil, providing amounts of 16∶0 and 18∶1 closer to milk, or a mix of soy, high-oleic sunflower and flaxseed oils with C₁₆ and C₁₈ fatty acids similar to canola oil but without 22∶1. Biochemical analysis found no differences in heart triglyceride concentrations among the groups at 10 or 18 d. Assessment of heart triglycerides using Oil Red O staining in select treatments confirmed no differences between 10-d-old piglets fed formula with 100% canola oil (n=4), 100% soy oil (n=4), or the soy oil blend (n=2). Levels of 22∶1n−9 in heart triglyceride and phospholipid, however, were higher (P<0.01) in piglets fed 100% canola oil or the canola oil blend, with higher levels found in triglycerides compared with phospholipids. The modest accumulation of 22∶1n−9 associated with feeding canola oil was not associated with biochemical evidence of heart triglyceride accumulation at 10 and 18 d.     

Molecular Characterization of a Lysophosphatidylcholine Acyltransferase Gene Belonging to the MBOAT Family in Ricinus communis L.

Acyl-CoA:lysophosphatidylcholine acyltransferase (LPCAT, EC 2.3.1.23) catalyzes acylation of lysophosphatidylcholine (lysoPtdCho) to produce phosphatidylcholine (PtdCho), the main phospholipid in cellular membranes. This reaction is a key component of the acyl-editing process, involving recycling of the fatty acids (FA) mainly at the sn-2 position of PtdCho. Growing evidences indicate that the LPCAT reaction controls the direct entry of newly synthesized FA into PtdCho and, at least in some plant species, it has an important impact on the synthesis and composition of triacylglycerols. Here we describe the molecular characterization of the single LPCAT gene found in the genome of Ricinus communis (RcLPCAT) that is homologous to LPCAT genes of the MBOAT family previously described in Arabidopsis and Brassica. RcLPCAT is ubiquitously expressed in all organs of the castor plant. Biochemical properties have been studied by heterologous expression of RcLPCAT in the ale1 yeast mutant, defective in lysophospholipid acyltransferase activity. RcLPCAT preferentially acylates lysoPtdCho against other lysophospholipids (lysoPL) and does not discriminates the acyl chain in the acceptor, displaying a strong activity with alkyl lysoPL. Regarding the acyl-CoA donor, RcLPCAT uses monounsaturated fatty acid thioesters, such as oleoyl-CoA (18:1-CoA), as preferred donors, while it has a low activity with saturated fatty acids and shows a poor utilization of ricinoleoyl-CoA (18:1-OH-CoA). These characteristics are discussed in terms of a possible role of RcLPCAT in regulating the entry of FA into PtdCho and the exclusion from the membranes of the hydroxylated FA.     

Lysophosphatidylcholine Acyltransferase 3 Is the Key Enzyme for Incorporating Arachidonic Acid into Glycerophospholipids during Adipocyte Differentiation

Cellular membranes contain glycerophospholipids, which have important structural and functional roles in cells. Glycerophospholipids are first formed in the de novo pathway (Kennedy pathway) and are matured in the remodeling pathway (Lands’ cycle). Recently, lysophospholipid acyltransferases functioning in Lands’ cycle were identified and characterized. Several enzymes involved in glycerophospholipid biosynthesis have been reported to have important roles in adipocytes. However, the role of Lands’ cycle in adipogenesis has not yet been reported. Using C3H10T1/2, a cell line capable of differentiating to adipocyte-like cells in vitro, changes of lysophospholipid acyltransferase activities were investigated. Lysophosphatidylcholine acyltransferase (LPCAT), lysophosphatidylethanolamine acyltransferase (LPEAT) and lysophosphatidylserine acyltransferase (LPSAT) activities were enhanced, especially with 18:2-CoA and 20:4-CoA as donors. Correspondingly, mRNA expression of LPCAT3, which possesses LPCAT, LPEAT and LPSAT activities with high specificity for 18:2- and 20:4-CoA, was upregulated during adipogenesis. Analysis of acyl-chain compositions of phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) showed a change in their profiles between preadipocytes and adipocytes, including an increase in the percentage of arachidonic acid-containing phospholipids. These changes are consistent with the activities of LPCAT3. Therefore, it is possible that enhanced phospholipid remodeling by LPCAT3 may be associated with adipocyte differentiation.     

木里坳陷油气成藏条件与成藏模式

利用钻井、露头分析化验资料和地震资料,研究了木里坳陷烃源岩地球化学特征、储层特征、构造演化史和油气成藏模式。结果表明,木里坳陷的石炭系、上三叠统尕勒得寺组和侏罗系发育有利烃源岩,其中,钻井揭示了上三叠统尕勒得寺组和侏罗系两套烃源岩;木里坳陷的储层物性差,以致密储层为主,储层微裂缝发育,裂缝为主要储集空间;木里坳陷经历三个构造演化阶段,发育继承性断裂;断裂与岩性共同控制着油气成藏类型,油气成藏类型多样。     

A MALDI MS Investigation of the Lysophosphatidylcholine/Phosphatidylcholine Ratio in Human Spermatozoa and Erythrocytes as a Useful Fertility Marker

The human spermatozoa membrane is characterized by a unique fatty acyl composition with significant amounts of highly unsaturated fatty acids, particularly docosahexaenoic acid (22:6), whereby phosphatidylcholine (PtdCho) (16:0/22:6) is the most abundant glycerophospholipid. The large amount of highly unsaturated fatty acyl residues is crucial for the fluidity of the membrane and, therefore, the successful fertilization process. Consequently, however, the spermatozoa are very sensitive to reactive oxygen species (ROS) that are generated under conditions of “oxidative stress” and key players in many pathological conditions. Lipid oxidation of the sperm membrane is accompanied by the loss of the oxidatively modified unsaturated residue (normally in the sn-2 position) and the generation of saturated lysophosphatidylcholine (LysoPtdCho). Although other lysolipids are also generated, LysoPtdCho is the “marker” lipid of choice due to the high abundance of PtdCho. In particular, obesity (body mass index >30 kg/m²) is characterized by increased ROS generation and negatively affects the reproductive potential. We will show here that the LysoPtdCho/PtdCho ratio can be easily determined by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). The data found do correlate with clinical markers of sperm quality. A very interesting aspect is that the LysoPtdCho/PtdCho ratios determined in the spermatozoa extracts correlate with the LysoPtdCho/PtdCho values determined in the organic extracts of erythrocytes. Thus, there is no absolute need for a sperm investigation, but an estimation of the fertilizing ability of the corresponding male could be also made directly from the blood which is more readily available than the spermatozoa.     

Lysophosphatidylcholine acyltransferase activity in Saccharomyces cerevisiae: Regulation by a high-affinity Zn2+ binding site

Saccharomyces cerevisiae cells were demonstrated to contain lysophosphatidylcholine (lysoPtdCho) acyltransferase (E.C. 2.3.1.23) activity. The enzyme displayed K _m(app) of 69 μM for lysoPtdCho and 152 μM for oleoyl CoA. Enzyme activity was not affected by the addition of 1 mM Mg²⁺, Mn²⁺, Ca²⁻, or 200 mM EDTA. However, Zn²⁺ inhibited lysoPtdCho acyltransferase activity to 33% control values at 0.1 mM and to 7% at 1.0 mM Zn²⁺. To further explore the possibility that lysoPtdCho acyltransferase may contain a high-affinity Zn²⁺ binding site, we tested the strong Zn²⁺ chelator o-phenanthroline for its ability to inhibit enzyme activity. LysoptdCho acyltransferase activity was inhibited to 18 and 27%, respectively, those of control values in the presence of 2 and 1 mM o-phenanthroline, implying that a high-affinity Zn²⁺ binding site exists in lysoPtdCho acyltransferase or in an accessory protein that is essential for protein stability and/or activity. Saccharomyces cerevisiae lysoPtdCho acyltransferase activity displayed a broad lysoPtdCho fatty acyl chain substrate specificity utilizing lysoPtdCho molecules ranging in length from C₁₀−C₂₀ (the entire range tested). In addition, the enzyme was capable of using the ether-linked analog of lysoPtdCho, 1-O-alkyl-2-hydroxy-sn-3-glycerophosphocholine, as a substrate. The ability of S. cerevisiae to incorporate radiolabeled 1-O-alkyl-2-hydroxy-sn-3-glycerophosphocholine into phosphatidylcholine in vitro was exploited to demonstrate a direct precursor-product relationship between lysoPtdCho molecules and their incorportation into phosphatidylcholine in vivo. Identical labeling results were obtained in S. cerevisiae cells disrupted for their major transacylase activity, PLB1, demonstrating that the incorporation of lysolipid was via acyltransferase, and not transacylase, activity.     

Water accumulation in the alcohol extraction of cottonseed

The critical moisture content of cottonseed flakes extracted with an aqueous alcohol solvent can be defined as that flake moisture level at which the flakes lose no moisture during extraction. This study shows that the critical moisture content for aqueous ethanol (92%, w/w) is 3%. For aqueous isopropanol (88%, w/w) this value is 6%. If the moisture contents of the flakes are above these levels, then the solvents pick up moisture. For moisture contents below this level, the flakes adsorb moisture and actually dry the alcohol. It is proposed that this latter capability can be used as a basis for a method to control water accumulation in aqueous alcohol solvent extractions.     

Protective Effects of EPA and Deleterious Effects of DHA on eNOS Activity in Ea hy 926 Cultured with Lysophosphatidylcholine

Oxidized low density lipoprotein (Ox-LDL) is a well-established risk factor in atherosclerosis and lysophosphatidylcholine (LysoPtdCho) is considered to be one of the major atherogenic component of Ox-LDL. The purpose of this work was to investigate the effects of two membrane n-3 long chain polyunsaturated fatty acids (n-3 PUFAs), EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) compared to n-6 PUFA, ARA (arachidonic acid), on the activation of endothelial NO synthase (eNOS) by histamine in Ea hy 926 endothelial cells incubated during 24 h in the presence or the absence of LysoPtdCho. DHA (50 μM) produced a ROS induction in cells and aggravated the LysoPtdCho-induced oxidative stress. It did not modify the basal eNOS activity but impaired the stimulation of eNOS induced by histamine and was unable to correct the deleterious effect of LysoPtdCho on histamine-stimulated eNOS activity or phosphorylation of Ser 1177. In contrast, EPA (90 μM) did not modify the ROS level produced in the presence or absence of LysoPtdCho or basal eNOS activity and the stimulating effect of histamine on eNOS. However, it diminished the deleterious effect of LysoPtdCho as well as on the histamine-stimulated eNOS activity on the phosphorylation on Ser 1177 of eNOS. The beneficial effect of EPA but not DHA on endothelial eNOS activity in Ea hy 926 could be also partially due to a slight decrease in membrane DHA content in EPA-treated cells. Consequently, the equilibrium between NO generated by eNOS and ROS due to oxidative stress could explain, in part, the beneficial effect of EPA on the development of cardiovascular diseases. By contrast ARA an n-6 PUFA was devoid of any effect on ROS generation or eNOS activity in the basal state or after histamine-induced stimulation. In vivo experiments should be undertaken to confirm these results.     

试论现代陶艺中的历史积淀

在陶艺发展的历史当中,宗教、政权、文化对其产生了非常深远的影响。由于长期封建政权的统治,解放后相当长的一段时间内工艺美术事业又不受重视,导致我国现代陶艺的发展比较滞后,准确地说从二十世纪九十年代才开始发展,这与西方一百余年前传统陶艺向现代陶艺就已开始转型不同。     

Differential utilization of long chain fatty acids during triacylglycerol depletion. I. Rat heart after ischemic perfusion

Rat hearts were perfused with Krebs-Henseleit buffer for 90 min according to the Langendorff procedure. Normoxic perfusion for 90 min resulted in minor changes in fatty acid composition and a decrease in residual heart triacylglycerol to 60% of preperfusion values. When the protocol included 30 min of slow perfusion-induced ischemia, the hearts were observed to be depleted of 89% of their initial triacylglycerol content. The triacylglycerol fatty acid composition (mg %) remained similar after compared to before perfusion except for a 121 mg % increase in stearic acid and a 225 mg % increase in arachidonic acid. The percentage composition of both fatty acids was significantly inversely correlated with the amount of triacylglycerol remaining in the heart after perfusion. Postperfusion, arachidonic acid and stearic acids were present at nearly 1∶1 in the residual heart triacylglycerol, suggesting that a common mechanism may be involved in the selective retention of these fatty acids by the heart. This paper was presented in part at the annual meeting of the Canadian Federation of Biological Societies, Guelph, Ontario, June 16–22, 1986. S.C.C. was the recipient of an Industrial Research Fellowship from the National Science and Engineering Research Council of Canada (1982–1986).     

Biosynthesis of brain sphingolipids and myelin accumulation in the mouse

Microsomal fractions were prepared from the brains of mice sacrificed at 13 are points between 5 and 48 days of age. Several enzymatic activities implicated in sphingolipid biosynthesis were assayed. The developmental pattern for the terminal step in galactosylceramide synthesis, transfer of galactose from UDP-galactose to ceramide, peaked sharply at 17–19 days of age. Thus maximal activity for biosynthesis of this relatively myelin specific lipid appears slightly before the time period of maximal rate of accumulation of myelin (21–23 days). These latter data were obtained by isolating myelin from mice at 10 age points from 9 to 45 days of age. A control enzymatic activity, transfer of glucose from UDP-glucose to ceramide to form glucosylceramide, was high at all age points with a broad peak between 20 and 35 days of age. Condensation of palmitoyl-CoA and serine to form ketodihydrosphingosine, a common precursor to both glucosyl- and galactosylceramide also followed a developmental pattern of high activity at all age points, but peaked slightly at ca. 10–12 days of age.     

Iron accumulation in oil during the deep-fat frying of meat

Iron accumulation in oil is a potential problem when frying food containing substantial amounts of iron. Selected meat products (skinless chicken breast, beef liver, and lean beef) were ground and fried (ca. 2-cm spheres, ca. 10 g/sphere) in partially hydrogenated soybean oil (PHSBO). Samples (450 g) of ground meat were fried 3 times/h for 8 h/d for 3 d. Oil samples were collected for analysis for iron (every 8 h) and oil degradation (every 4 h) and replaced with fresh oil. The iron contents of oil samples after 3 d of frying were approximately 0.11, 0.48, and 4.01 mg of iron/kg of PHSBO for the oil used to fry chicken, beef, and liver, respectively. There was a notable darkening in color and an increased tendency to foam for the beef liver oil sample compared with the other samples. After frying, the acid values were 0.9, 1.1, and 1.4 for the oil samples for chicken, beef, and liver, respectively. After frying, the p-anisidine values were 11.5, 12.8, and 32.6 for the oil samples for chicken, beef, and liver, respectively; the food oil sensor values were 0.96, 0.96, and 0.83 for the oil samples for chicken, beef, and liver, respectively.