Lung surfactant phospholipids in different animal species

A comparative study of adult mammalian lung surfactants was undertaken to determine which animal species might serve as appropriate models for surfactant alterations in human lung diseases. Phosphatidylcholine (PC) comprised 80–87% of the phospholipid and contained more than 65% palmitic acid in all species studied. Phosphatidylglycerol (PG) was found to vary significantly in fatty acid composition among the species. Rabbit, dog and rat surfactant PG contained 50–60% palmitic acid, while human and cat surfactant contained much lower levels of saturated fatty acids. Both the PC and PG of all species contained 2 positional isomers of fatty acids with 16 carbons and one double bond, but the relative amounts of the unusual isomer, 16∶1Δ7, and palmitoleic, acid, 16∶1Δ9, varied among the different animal species. Only cat and dog surfactant phospholipids contained 18∶1Δ5. Cat surfactant phospholipids also differed by the absence of 20∶4 and the presence of small amounts of several 20- and 22-carbon fatty acids. These results explain some discrepancies found in the literature concerning surfactant composition and delineate limiting factors in extrapolating results from animal studies for the evaluation of maturation and pathological alterations in human surfactant.     

Accumulation of acidic phospholipids in a case of hyperlipidemia with hepatosplenomegaly

The results of studies made on an adult patient with hepatosplenomegaly, hyperlipidemia and accumulation of acidic phospholipids in the liver are presented. Storage of a lipoid substance was demonstrated histologically in lymph nodes, the liver and the bone marrow. Lipid analysis of the biopsy specimen from the liver revealed marked elevations of free cholesterol and two classes of acidic phospholipids: phosphatidyl inositol and another one which was tentatively identified as lysobisphosphatidic acid. Electron microscopic examination showed cytoplasmic inclusions with concentrically laminated structure.     

Fluorescent products of phospholipids during lipid peroxidation

During peroxidation, phosphatidyl ethanolamine and phosphatidyl serine formed fluorescent chromophores with maximum emission at 435 nm and maximum excitation at 365 nm. The development of fluorescence was related to formation of thiobarbituric acid reactive substance during lipid peroxidation. This relationship was studied by reacting dipalmityl phosphatidyl ethanolamine with the oxidation products of the methyl esters of arachidonic, linolenic and linoleic fatty acids. Reaction parameters affecting the development of lipid-extractable fluorescent chromophores are: the production of peroxidation products, especially malonaldehyde, from autoxidation of polyunsaturated fatty acids; the length of time these products react; and the availability of reactive amino groups on the phospholipids.     

蒸馏一色谱法测定煤焦油中甲基萘含量

建立了蒸馏．色谱法测定煤焦油中甲基萘含量的分析方法。以乙醇为溶剂,将煤焦油蒸馏后馏分采用HP-5毛细管柱分离,氢火焰离子化检测器检测,外标法对甲基萘中β-甲基萘和α-甲基萘进行定性定量分析。该方法分离效果好,所测定的结果具有良好的准确度和精密度,样品的回收率在97．8％～103．5％。     

Accumulation of eicosapentaenoic acid in plasma phospholipids of subjects fed canola oil

The metabolism of α-linolenic acid from canola oil was studied in eight normolipidemic men. The 42-day study was divided into three periods: a 6-day pre-experimental and two 18-day experimental. Approximately 75% of the dietary fat (28% of total energy) was provided by a mixture of fats during the pre-experimental period and either canola oil (CO) or sunflower oil (SO) during the experimental periods. The CO and SO diets were fed in a cross-over design. The ratios of linoleic to linolenic acid were 2.6∶1 and 73.9∶1 in the CO and SO diets, respectively. Dietary fat source had an effect on plasma phospholipid fatty acids: 18∶1n−9, 18∶3n−3 and 20∶5n−3 were higher (p<0.05), and 18∶2n−6 was lower in the phosphatidylcholine fraction; 18∶1n−9 was higher and 20∶4n−6 lower in the phosphatidyl-ethanolamine fraction; and 18∶1n−9 and 20∶5n−3 were higher and 20∶4n−6 and 22∶6n−3 were lower in the alkenylacyl-ethanolamine phospholipid fraction on the CO diet as compared to the SO diet. Consumption of the canola oil diet resulted in higher n−3 fatty acid levels and lower n−6 fatty acid levels in plasma phospholipids than consumption of the sunflower oil diet.     

气相色谱法测定洗油中甲基萘的含量

建立了洗油中甲基萘含量的毛细管气相色谱测定方法。该法以甲苯为溶剂,采用HP-5毛细管柱分离,氢火焰离子化检测器检测,外标法对甲基萘中1-甲基萘和2-甲基萘定量分析。该方法分离效果好,具有很好的准确度和精密度,整个试样分析时间不超过15 min,样品的回收率在97.7%～101.0%。     

The composition of cardiac phospholipids in rats fed different lipid supplements

Changes in dietary lipid intake are known to alter the fatty acid composition of cardiac muscle of various animals. Because changes in cardiac muscle membrane structure and function may be involved in the pathogenesis of arrythmia and ischemia, we have examined the effects of dietary lipid supplements on the phospholipid distribution and fatty acid composition of rat atria and ventricle following 20 weeks feeding of diets supplemented with either 12% sunflower-seed oil or sheep fat. Neither lipid supplement produced significant changes in the proportions of cholesterol, total phospholipids or phosphatidylcholine, phosphatidylethanolamine or diphosphatidylglycerol,—the phospholipid classes that together account for more than 90% of the total phospholipids of rat cardiac muscle. Significant changes were found in the profiles of the unsaturated fatty acids of all 3 phospholipid components of both atria and ventricle. Although similar, the changes between these tissues were not identical. However, in general, feeding a linoleic acid-rich sunflower seed oil supplement resulted in an increase in the ω-6 family of fatty acids, whereas feeding the relatively linoleic acid-poor sheep fat supplement decreased the level of ω-6 fatty acids but increased the levels of the ω-3 family, resulting in major shifts in the proportions of these families of acids. In particular, the ratio of arachidonic acid: docosahexaenoic acid (20∶4, ω-6/22∶6, ω-3), which is higher in all phospholipids of atria than ventricle, is increased by feeding linoleic acid, primarily by increasing the level of arachidonic acid in the muscle membranes. As dosahexaenoic acid does not occur in the diet, the increase in this acid which occurs after feeding animal fat, presumably arises from increased conversion of the small amounts of linolenic acid in all diets when the amount of linoleic acid present is reduced.     

Source of lung surfactant phospholipids: Comparison of palmitate and acetate as precursors

The phospholipids and the fatty acid compositions of major phospholipids in rat lung parenchyma, microsomes, lamellar bodies and alveolar wash were quantified. Adult rats were injected simultaneously with [³H] palmitate and [¹⁴C] acetate into the femoral vein. The appearance of labeled phosphatidylcholine (PC), disaturated phosphatidylcholine (DSPC) and phosphatidylglycerol (PG) in each lung fraction was measured during short periods of time (5 min to 2 hr) after isotope administration. Relatively more PC, DSPC and PG labeled with acetate radioactivity in lung microsomes entered lamellar body and alveolar wash fractions than those labeled with palmitate radioactivity. However, there was no difference between palmitate and acetate labeled phospholipids in the transport from microsomes to lamellar bodies by phospholipid exchange proteins. On the other hand, prior injection of colchicine resulted in decrease in the transport of PC from microsomes to alveolar space to a relatively greater extent in the acetate radioactivity than in the palmitate radioactivity.     

Ether lipid content and fatty acid distribution in rabbit polymorphonuclear neutrophil phospholipids

This study was undertaken to determine if rabbit neutrophils contain sufficient ether-linked precursor for the synthesis of 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine (platelet activatin factor) by a deacylation-reacylation pathway. The phospholipids from rabbit peritoneal polymorphonuclear neutrophils were purified and quantitated, and the choline-containing and ethanolamine-containing phosphoglycerides were analyzed for ether lipid content. Choline-containing phosphoglycerides (37%), ethanolamine-containing phosphoglycerides (30%), and sphingomyelin (28%) were the predominant phospholipid classes, with smaller amounts of phosphatidylserine (5%) and phosphatidylinositol (<1%). The choline-linked fraction contained high amounts of 1-O-alkyl-2-acyl-(46%) and 1,2-diacyl-sn-glycero-3-phosphocholine (54%), with a trace of the 1-O-alk-1′-enyl-2-acyl species. The ethanolamine-linked fraction contained high amounts of 1-O-alk-1′-enyl-2-acyl-(63%) and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (34%), and a low quantity of the 1-O-alkyl-2-acyl species (3%). The predominant 1-O-alkyl ether chains found in thesn-1 position of the choline-linked fraction were 16∶0 (35%), 18∶0 (14%), 18∶1 (26%), 20∶0 (16%), and 22∶0 (9%). The major 1-O-alk-1′-enyl ether chains found in thesn-1 position of the ethanolamine-linked fraction were 14∶0 (13%), 16∶0 (44%), 18∶0 (27%), 18∶1 (12%) and 18∶2 (3%). The major acyl groups in thesn-1 position of 1,2-diacyl-sn-glycero-3-phosphocholine and 1,2-diacyl-sn-glycero-3-phosphoethanolamine were 16∶0, 18∶0 and 18∶1. The most abundant acyl group in thesn-2 position of all classes of choline- and ethanolamine-linked phosphoglycerides was 18⩺2. Although this work does not define the biosynthetic pathway for platelet activating factor, it does show that there is ample precursor present to support its synthesis by a deacylation-reacylation pathway.     

Accumulation of (n−9)-eicosatrienoic and docosatrienoic acids in human fibroblast phospholipids

An essential fatty acid (EFA) deficiency-like profile of fatty acids has been observed in HF-1 human skin fibro-blasts cultured at clonal densities in MCDB 110 and 0.4% fetal bovine serum (FBS). The profile was characterized by an accumulation of 16∶1n−7, 18∶1n−9, 20∶3n−9 and 22∶3n−9, a reduction of n−6 fatty acids and a reduction in total polyunsaturated fatty acids (PUFA). The fatty acid composition of sphingomyelin (SPH), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylinositol (PI) and phosphatidylethanolamine (PE) was determined and, except for SPH, each displayed an EFA deficiency-like profile. The triene to tetraene ratio (20∶3n−9/20∶4n−6) ranged from 5.3 in PI to 0.9 in PE. In addition, the highest percentage of 20∶3n−9 was present in the PI and the highest percentage of 22∶3n−9, in PE. Other human fibroblasts (normal, transformed and at different population doubling number levels [PDL] were grown under the same conditions and were found to display triene to tetraene ratios (20∶3n−9/20∶4n−6) in total cellular lipids ranging from 0.7 to 4.5. The accumulation of 20∶3n−9 and 22∶3n−9 is due primarily to the existence of a basal nutrient medium (MCDB 110) that allows for the rapid clonal growth of human fibroblasts at reduced serum levels (0.4%). This culture procedure can be exploited to further elucidate various aspects of lipid metabolism in human fibroblasts. Fatty acids are abbreviated as number of carbon atoms: number of double bonds, followed by an n-number to designate the position of the first double bond with respect to the methyl carbon. Thus, Mead acid is 20∶3n−9 and its elongation product is 22∶3n−9.     

Effects of phospholipids on lipid oxidation of a salmon oil model system

Total lipid (TL), neutral lipid (NL), and phospholipid (PL) fractions were extracted from bluefish (Pomatomus saltatrix) white and dark muscle with skin. The effects of each fraction on the oxidative stability of a refined salmon oil model system was measured by monitoring changes in the 2-thiobarbituric acid assay and decreases in the ratio of docosahexaenoic acid (DHA) to palmitic acid (C22:6/C16:0) following incubation at 55°C or 180°C. Phospholipid fractions at 2.5% and 5.0% (wt/wt) of oil improved the oxidative stability of oils incubated at both temperatures compared to controls, TL- and NL-supplemented oils at similar concentrations. Phospholipid fractions exhibiting antioxidant properties contained an average of 34% DHA as compared to only 15% in the NL and TL fractions.     

Role of lipid structure in the activation of phospholipase A2 by peroxidized phospholipids

The time course of hydrolysis of a mixed phospholipid substrate containing bovine liver 1,2-diacyl-sn-glycero-3-phosphocholine (PC) and 1,2-diacyl-sn-glycero-3-phosphoethanolamine (PE) catalyzed byCrotalus adamanteus phospholipase A₂ was measured before and after peroxidation of the lipid substrate. The rate of hydrolysis was increased after peroxidation by an iron/adenosine diphosphate (ADP) system; the presence of iron/ADP in the assay had a minimal inhibitory effect. The rate of lipid hydrolysis was also increased after the substrate was peroxidized by heat and O₂. Similarly, peroxidation increased the rate of hydrolysis of soy PC liposomes that did not contain PE. In order to minimize interfacial factors that may result in an increase in rate, the lipids were solubilized in Triton X-100. In mixtures of Triton with soy PC in the absence of PE, peroxidation dramatically increased the rate of lipid hydrolysis. In addition, the rate of hydrolysis of the unoxidizable lipid 1-palmitoyl-2-[1-¹⁴C]oleoyl PC incorporated into PC/PE liposomes was unaffected by peroxidation of the host lipid. These data are consistent with the notions that the increase in rate of hydrolysis of peroxidized PC substrates catalyzed by phospholipase A₂ is due largely to a preference for peroxidized phospholipid molecules as substrates and that peroxidation of host lipid does not significantly increase the rate of hydrolysis of nonoxidized lipids.     

Fatty acid composition of lung,macrophage and surfactant phospholipids after short-term enteral feeding with n−3 lipids

Utilization of enteral feeding modalities may prove clinically relevant for rapid modulation of lung phospholipid polyunsaturated fatty acids (PUFA) that serve as substrates for the formation of vasoactive dienoic eicosanoids. We compared the effects of short-term enteral feeding with formulations enriched with either fish (n−3) or corn (n−6) oil PUFA on the fatty acid composition of rat lung, alveolar macrophage and surfactant phospholipids. The diets were infused continuously for 72 h through a surgically placed gastroduodenal feeding catheter by a syringe pump. The n−3 PUFA derived from the fish oil enriched diet were readily incorporated into the phospholipid membranes of the alveolar macrophages, lung tissue and pulmonary surfactant. The relative percentages of the n−3 PUFA were significantly higher and individual and total n−6 PUFA significantly lower in the macrophage, lung and surfactant phospholipids from the n−3-supplemented rats in comparison with those present in the rats infused enterally with the n−6 diet or untreated, chow-fed rats (baseline). In contrast, there was a significant increase in linoleic acid (18∶2n−6) without modification of arachidonic acid (20∶4n−6) in the alveolar macrophages, lung tissue and surfactant from rats enterally receiving the n−6 diet relative to levels measured in the rats at baseline. The results suggest that short-term continuous delivery of n−3-enriched enteral preparations can foster rapid modification of membrane phospholipid PUFA composition of lung tissue, alveolar macrophages and lung surfactant. Utilization of similar infusion modalities to deliver n−3-enriched enteral formulations may prove beneficial to critically ill or postoperative patients with persistent lung inflammation secondary to uncontrolled formation of vasoactive eicosanoids derived from arachidonic acid.     

Accumulation of phospholipids and glycolipids in seed kernels of different sunflower mutants (Helianthus annuus)

Phospholipids are essential components of the oil bodies present in seeds, and they are also the main components of the commercial seed lecithins used in many food formulas. In the present study, we analyzed the characteristics of the polar lipid fraction of seeds from different sunflower FA mutants. In sunflower seeds the accumulation of polar lipids reaches a maximum 25 d after anthesis before diminishing during the final stages of maturation and desiccation. We have developed an HPLC method, using ELSD, that produces optimal separation of all polar seed lipids. This method improves the results that could be obtained with previous HPLC methods and hence, we have used it to analyze the polar lipid fraction of sunflower seeds. We show that this fraction comprises phospholipids and glycolipids, of which PC is the most abundant species. Moreover, we found that the relative polar lipid content in control and mutant seeds is similar, suggesting that the mutant traits do not affect polar lipid synthesis. The degradation of polar lipids in isolated seeds was also examined and we found that the PC and PE present in developing sunflower seed kernels were rapidly degraded owing to the activity of D-type phospholipases.     

Human placental lipid metabolism. III. Synthesis and hydrolysis of phospholipids

Both diacyl GPC (glycerylphosphorylcholine) and diacyl GPE (glycerylphosphorylethanolamine) are synthesized in human placental tissue from their respective monoacyl precursors. The origin of the monacyl phosphatides is apparently not the result of placental phosphatide acyl-hydrolase activity. The most likely source is maternal serum. The declining level of 1-acyl GPC in maternal serum is not attributable to lysophosphatide acylhydrolase activity and is probably explained by placental utilization for the synthesis of diacyl GPC.     

Enhancement of conversion and selectivity by temperature-swing unsteady-state reaction method in shape-selective methylation of methylnaphthalene with ZSM-5

In order to enhance the conversion of shape-selective methylation of 2-methylnaphthalene with HZSM-5 for producing 2,6-dimethylnaphthalene, an important precursor of high performance polyester, effect of reaction method was investigated. It was found that an unsteady-state reaction method with adsorption at a low temperature and subsequent flush at somewhat elevated temperature was very effective for enhancing the conversion drastically. This new reaction method, named low temperature adsorption and flush (LTAF) method, made it possible to increase the conversion up to more than 70% without losing shape-selectivity, whereas, by the conventional steady-state reaction method, the conversion remained at 10-20% level due to restricted diffusion of naphthalene-ring compounds in the HZSM-5 pore which was essential for the shape-selectivity. By LTAF method, the methylation can be performed in the range of temperature lower than that required for steady-state reaction, and the methanol conversion as a side reaction was effectively suppressed.     

The effects of dietary fish oil on alveolar type II cell fatty acids and lung surfactant phospholipids

The purpose of this study was to determine the responsiveness of alveolar type II cells to dietary fish oil and the consequent effects on alveolar and lung surfactant. Rats were fed a corn oil or a fish oil diet for four weeks. Dietary n−3 fatty acids were readily incorporated into the type II cell phospholipids as indicated by higher levels of eicosapentaenoic acid (2.77±0.10%) and docosahexaenoic acid (1.63±0.10%) in the group receiving the fish oil diet. The elevated levels of n−3 fatty acids were accompanied by concomitant reduction in arachidonic acid and linoleic acid. Neither eicosapentaenoic acid nor docosahexaenoic acid was incorporated into type II cell triacylglycerols. Feeding a fish oil containing diet increased surfactant phospholipids, particularly 1,2-disaturated acyl phosphatidylcholines in whole lung compared to a corn oil diet. However, the amount of surfactant found in the alveolus was not different between the two diet treatment groups. The results suggest that dietary n−3 fatty acids stimulate synthesis and/or inhibit degradation of lung surfactant without altering surfactant secretion in alveoli.     

Detergent induced changes in serum lipid composition in rats

The influence ofin vivo administration of detergents on serum lipid composition was studied in rats. Male Wistar rats received 50 mg Emulgen 913 (polyoxyethylene nonylphenylether, a nonionic detergent) or SDS (sodium dodecylsulfate, an anionic detergent) per kg of body weight intraperitoneally for 3 consecutive days. Emulgen 913 and SDS administration increased the level of cholesterol esters and phospholipids, respectively. But Emulgen 913 administration reduced the level of triglycerides in the Serum, and SDS administration reduced also the levels of triglycerides and cholesterol esters. In spite of the changes in serum lipid composition, the administration of these detergents did not affect the amount of total lipids in rat serum. The proportion of palmitic, oleic, and docosahexaenoic acids in phospholipids was decreased by the administration of Emulgen 913 while the level of arachidonic acid was raised. However, the level SDS administration had no effect on the fatty acid composition of the serum phospholipids. On the other hand, both Emulgen 913 and SDS administration showed an effect on the fatty acid composition of triglycerides. It is postulated that liver damage due to administration of detergents is responsible for the changes in serum lipid and fatty acid composition in detergent-treated rats.