Neutrophil phosphatidylcholine (PC) composition in cystic fibrosis (CF).
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Adult↗
Biomedical subjects
A D Postle
Publications and source records attributed to A D Postle.
Is gastric surfactant related to lung surfactant.
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1,2-Dipalmitoylphosphatidylcholine↗
Conductive airway surfactant: surface-tension function, biochemical composition, and possible alveolar origin.
Alveolar surfactant is well known for its ability to reduce minimal surface tension at the alveolar air-liquid interface to values below 5 mN/m. In addition, it has been suggested that an analogous conductive airway surfactant is also present in the airways. To elucidate the composition, possible origin, and surface activity of conductive airway phospholipids (PL), we compared in adult porcine lungs the PL classes and phosphatidylcholine (PC) molecular species of nonpurified tracheal aspirate samples with those of bronchoalveolar lavage fluid (BAL), tracheobronchial epithelium, and lung parenchyma. We also analyzed PL and PC composition, protein content, and surface activity of surfactant isolated from tracheal aspirates (SurfTrachAsp), BAL (SurfBAL), and the 27,000 x g pellet of BAL (SurfP27000) by density-gradient centrifugation. Although PL composition revealed contributions of the airways to tracheal aspirates, the composition of PC molecular species of tracheal aspirates was similar to that of BAL and lung parenchyma, but differed considerably from that of airway epithelium. SurfTrachAsp had the same PL and PC composition as SurfBAL and SurfP27000, indicating that this fraction of tracheal aspirates may have originated from the alveoli. Nevertheless, minimal and maximal surface tensions were higher in SurfTrachAsp than in SurfBAL and SurfP27000. Analysis of surfactant proteins A, B, and C (SP-A, SP-B, and SP-C) revealed that SP-A was decreased and SP-B and SP-C were absent, whereas total protein was increased in SurfTrachAsp. We conclude that as compared with alveolar surfactant, PL of SurfTrachAsp show the same composition, but that surface-tension function is impaired and the concentration of surfactant proteins is decreased in SurfTrachAsp.
Analysis of Variance↗
Phospholipid composition of neonatal guinea pig liver and plasma: effect of postnatal food restriction.
Preterm guinea pigs were delivered on day 65 of gestation (term = 68 d) and were allowed either free or restricted access to food for the subsequent 48 h. Plasma phosphatidylcholine (PC) concentration increased postnatally from 190 (range 144-307) to 751 (426-1039) and 883 (758-977) microM for fed and starved pups, respectively. Plasma PC composition in both groups of pups was characterized by selective and equivalent relative increases to individual molecular species containing 18:0 at the sn-1 position. Hepatic PC concentration increased from 6.75 (5.41-8.20) to 8.65 (6.54-10.63) and 9.23 (8.18-10.17) mumol/g for fed and starved pups, respectively, and, under all conditions, hepatic PC molecular composition closely mirrored that of plasma PC. These results support the hypothesis that the molecular species composition of plasma PC for the guinea pig in the immediate postnatal period is determined largely by the composition of the hepatic PC pool destined for lipoprotein secretion. Hepatic PC composition and concentration of the starved neonatal guinea pig were maintained independently of any dietary nutrient intake, at the expense of mobilization of extra hepatic lipid reserves. While this adaptive mechanism has inherent limited survival potential in neonatal starvation, it has implications for studies measuring plasma phospholipid fatty acid compositions as biochemical markers of dietary fat intake in preterm infants.
Aging↗
Rat gastric hydrophobic barrier: modulation of phosphatidylcholine molecular species by dietary lipids.
Phospholipids protect the gastric mucosa by forming a proton-repellent hydrophobic layer on its luminal surface. We have recently shown that two molecular species of phosphatidylcholine (PC), PC16:0/18:1, and PC16:0/18:2, but not PC16:0/16:0, are predominantly released into gastric mucus. We investigated whether these molecular species in mucus are modified by dietary fat. Rats were fed (for three weeks) a diet supplemented with either 10% cod liver, palm, or sunflower oil, or 10% corn starch as a control. In tissue, cod liver oil decreased PC16:0/20:4 and PC18:0/20:4. Cod liver oil and palm oil increased PC16:0/18:1, whereas sunflower oil decreased PC16:0/18:1. Palm oil additionally decreased PC16:0/18:2, whereas the other diets had no effect on PC16:0/18:2. In mucus, however, PC16:0/18:1 and PC16:0/18:2 were not significantly altered by any diet. They were increased over tissue values and comprised 37.6 +/- 3.3 and 33.1 +/- 1.4 mol% in controls. PC16:0/16:0 was lower in mucus than in mucosa and even decreased by cod liver oil (1.2 +/- 0.2 vs. 2.7 +/- 0.3 mol%; P < 0.01). We conclude that PC16:0/18:1 and PC16:0/18:2 are modified by dietary fat in tissue. In gastric secretions, however, PC16:0/18:1 and PC16:0/18:2 are kept constant and together comprise 70 mol% of the released PC species, whereas PC16:0/16:0 does not play a role for the gastric hydrophobic barrier under any dietary treatment. Additionally, cod liver oil decreases the content of PC16:0/20:4 and PC18:0/20:4 in gastric mucosa, thereby possibly decreasing the formation of eicosanoids.
Animals↗
Steroids, surfactant and lung disease.
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Dexamethasone↗
Ontogeny of circulating leucocytes in the fetal guinea pig.
The ontogeny of leucocytes in the fetal guinea pig was investigated. The total leucocyte concentration increased between days 40 and 56, but thereafter was unchanged at term (day 68). T and B lymphocytes were detected on day 56 and at term, and while T cell concentrations remained constant between day 56 and term, the concentration of B cells decreased. The ratio of CD4+ to CD8+ T cells increased from 0.9 on day 56 to 3.0 at term. All fetal cell concentrations were significantly lower as compared with adult animals. The fetal peripheral blood mononuclear cell proliferative responses to mitogenic stimulation increased from day 40 to 56, but tended to decrease between day 56 and term. The fetal proliferative responses were significantly lower as compared with adults. Comparison of these data with previous analyses of the pattern of human fetal lymphocyte development indicated that, although there were similarities, such as the timing of the first appearance of circulating lymphocytes, there were also differences, for example the changes which occur between birth and adulthood, between the two species. This suggests that the guinea pig may have a limited use as a model of some aspects of the ontogeny of the human immune system.
Animals↗
The composition of individual molecular species of plasma phosphatidylcholine in human pregnancy.
The molecular species composition of plasma phosphatidylcholine (PC) was measured in sequential blood samples from 13 pregnant women from 16 weeks of gestation to delivery at term. The increased total plasma PC concentration at term was due solely to increased concentrations of individual species containing palmitate (16:0) rather than stearate (18:0) at the sn-1 position. The specific increase of PC16:0/22:6 concentration in mid-gestation suggests that adaptations to maternal hepatic PC metabolism may provide a mechanism to ensure adequate supply of 22:6(n-3) to the fetus. While cord plasma PC was comparable to liver PC composition from three stillborn term infants, the compositions of these tissues differed from maternal plasma PC, which contained significantly more PC16:0/18:2 and PC18:0/18:2. These results suggest that, although fetal acquisition of polyunsaturated fatty acids (PUFA) is dependent on the maternal lipid supply, the detailed composition of fetal plasma PC may be regulated largely by intrinsic fetal mechanisms such as placental and liver PC metabolism. Similarly, the specific alterations to maternal plasma PC composition in pregnancy, which we postulate are associated with the supply of PUFA to the fetus, were substantially independent of variations in maternal dietary lipid nutrition.
Chromatography, High Pressure Liquid↗
Effect of maternal ethanol consumption during pregnancy on the phospholipid molecular species composition of fetal guinea-pig brain, liver and plasma.
The effect of maternal ethanol consumption during pregnancy upon accumulation of docosahexaenoic acid (22:6(n - 3)) into developing brain phospholipids was determined in a guinea-pig model of fetal alcohol syndrome. Feeding adult guinea-pigs 6 g/kg per day ethanol both before and throughout pregnancy was associated with decreased 22:6(n - 3) concentration in both fetal brain phosphatidylcholine (PC) and phosphatidylethanolamine (PE) at 40/68 days gestation and at term. Since adequate assimilation of 22:6(n - 3) into fetal brain is critical for optimal neuronal development, reduced accumulation of 22:6(n - 3) into phospholipids may be one important mechanism for ethanol-induced brain damage. Liver from ethanol-exposed fetuses contained significantly lower concentrations of both PC and PE 22:6(n - 3)-containing molecular species. However, there was no difference in plasma PC polyunsaturated fatty acid content in ethanol-exposed fetuses compared with controls. One possible explanation for impaired 22:6(n - 3) accumulation into ethanol-exposed fetal brain phospholipids may be the result of the action of inappropriate mechanisms which counteract ethanol-induced increased membrane fluidity by reducing the polyunsaturated fatty acid content of brain phospholipids.
Alcohol Drinking↗
The molecular selectivity of phospholipase D in HL60 granulocytes.
The molecular selectivity of PLD in PMA-stimulated HL60 granulocytes was determined by HPLC analysis of [3H]butanol incorporation into phosphatidyl[3H]butanol (Ptd[3H]But) molecular species. Comparison with phospholipid compositions confirmed that PLD acted primarily on phosphatidylcholine (PtdCho). Apparent enzyme selectivity was suggested by negligible formation of PB16:0/16:0 and preferential synthesis of Ptd[3H]But species containing sn-1 18:0. Culture with exogenous 18:2n-6 or 20:4n-6 readily modified both PtdCho and Ptd[3H]But compositions, and accentuated the apparent selectivity of stimulated PLD for sn-1 18:0 species of PtdCho. Such modifications to PLD-based signalling mechanisms may contribute to the modulatory effects of altered dietary lipid intakes on cellular functions.
Butanols↗
Composition of phospholipid classes and phosphatidylcholine molecular species of gastric mucosa and mucus.
Phospholipids have been proposed to protect the gastric mucosa by forming a proton-repellant hydrophobic layer on the gastric luminal surface, acting as a so-called gastric surfactant. The composition of this hydrophobic phospholipid layer has not previously been analysed in detail. Therefore, we measured the composition of phospholipid classes and phosphatidylcholine (PC) molecular species in gastric mucosa and mucus of rats and pigs using high resolution HPLC techniques. The predominant phospholipids of both mucosa and mucus were PC and phosphatidylethanolamine (PE). Little phosphatidylglycerol was present. The most abundant PC species of rat mucosa were PC16:0/18:1, PC16:0/18:2, PC16:0/20:4 and PC18:0/20:4. Pig mucosa also contained PC16:0/18:1, PC16:0/18:2, and PC18:0/20:4, but was poor in PC16:0/20:4. Dipalmitoyl-PC (PC16:0/16:0), the surface-active component of pulmonary surfactant, comprised only 6.42 +/- 0.33% of total PC in rat mucosa and only 5.50 +/- 1.46% of total PC in pig mucosa. Gastric mucus, isolated from both rat and pig, contained largely PC16:0/18:1 and PC16:0/18:2. The content of PC16:0/16:0 was even lower in mucus than in mucosal PC (rat 2.86 +/- 0.40%, P < 0.01; pig 1.92 +/- 0.55%, P < 0.05). We conclude that, in contrast to pulmonary surfactant, any surfactant function of the hydrophobic barrier of the stomach is unlikely to be mediated by PC16:0/16:0.
Animals↗
Phospholipid molecular species composition of developing fetal guinea pig brain.
Adequate accumulation of polyunsaturated essential fatty acids, in particular docosahexaenoic acid (22:6n-3), into membrane phospholipids is critical for optimal fetal brain development. This process is maximal during the period of rapid neurite outgrowth, neuritogenesis, which precedes the major growth phase, myelination. There is no information about differential changes during gestation to individual brain phospholipid molecular species which contain 22:6n-3. Such details of brain development would be concealed by total fatty acid analysis of isolated phospholipid classes. We have detailed phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecular species compositions in developing fetal guinea pig brain. Total brain PC concentration increased substantially between 40 and 68 (term) d of gestation, corresponding to myelination, while PE increased in a biphasic manner between 25-35 d, which was coincident with onset of neuritogenesis, and 40-68 d. Fetal brain development was accompanied by complex changes in the concentration of individual phospholipid molecular species. During early gestation (25-40 d) 22:6n-3 was enriched in both PC and PE sn-1 16:0 molecular species. However, between 40 d and term there was no further increase in brain PC 22:6n-3 content, while brain PE was significantly enriched in both PE18:1/22:6 and PE18:0/22:6. We hypothesize that accumulation of 22:6n-3 into sn-1 18:1 and 18:0 species represents establishment of a 22:6n-3-containing membrane PE pool which may be turned over more slowly than sn-1 16:0 species. Identification of specific changes in membrane phospholipids which are associated with defined events in brain development may provide a basis for assigning functional roles to individual molecular species.
Animals↗
Mammalian secreted and cytosolic phospholipase A2 show different specificities for phospholipid molecular species.
Previous studies using phospholipid vesicles containing single molecular species have shown cytosolic phospholipase (85 kDa) (PL) A2 to possess a marked preference for arachidonic acid (20:4n-6)-containing species, while secreted PLA2 (14 kDa) exhibited little acyl chain selectivity. In this study, we have defined the molecular specificity of cytosolic PLA2 using phospholipid vesicles derived from rat liver which contain complex mixtures of molecular species. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were isolated from rat liver by chloroform and methanol extraction, and solid-phase separation. PC and PE vesicles were hydrolysed by either human recombinant cytosolic or porcine pancreatic PLA2. Molecular species compositions were determined by reverse phase high performance liquid chromatography (HPLC) with post-column fluorescence derivitisation. HPLC analysis after limited hydrolysis demonstrated that the secreted phospholipase A2 showed no significant acyl chain specificity using these phospholipid mixtures. However, the cytosolic enzyme demonstrated a high degree of preference for arachidonic acid-containing species such that there was no hydrolysis of other molecular species. The extent of hydrolysis of PC16:0/20:4 was 1.4-fold greater (P < 0.05, n = 3) than PC18:0/20:4, while PE16:0/20:4 and PE18:0/20:4 were hydrolysed to a similar degree. Under these assay conditions, the cytosolic enzyme showed a preference for PE as compared with PC. This study confirms that cytosolic PLA2 is highly selective for sn-2 20:4n-6-containing phospholipid molecular species even when presented with a complex natural species mixture. This specificity is consistent with the cytosolic enzyme having a primary role in the process of arachidonic release within cells.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Synthesis of phosphatidyl[3H]butanol molecular species by phospholipase D in HL60 granulocytes.
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Animals↗
Substrate selectivity of phospholipase D in HL60 granulocytes: effects of fatty acid supplementation.
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Butanols↗
Mechanisms of hepatic phosphatidylcholine synthesis in adult rat: effects of pregnancy.
Late pregnancy in the rat (gestational ages 16-21 days) was accompanied by a specific increase in hepatic phosphatidylcholine (PC) and phosphatidylethanolamine (PE) molecular species containing C16:0 at the sn-1 position and polyunsaturated essential fatty acids (PUFA), in particular C22:6(n-3), at the sn-2 position. Incorporation of either CDP:[Me-14C]choline or CDP:[1,2-14C]-ethanolamine into hepatic microsomal sn-1 C16:0 PC or PE molecular species in vitro was greater at term than in non-pregnant animals, suggesting modifications to the composition of specific diacylglycerol (DAG) pools destined for synthesis of either PC or PE. Also, incorporation of [Me-14C]choline or [Me-14C]methionine into hepatic PC in vivo over 6 h in term pregnant rats was consistent with decreased phospholipase A1-dependent acyl remodelling of sn-1 C16:0 to sn-1 C18:0 molecular species. There was, however, no evidence to support any change to the specificity of acyl remodelling. The rate of PC synthesis by the de novo pathway in vivo was increased in term liver compared with non-pregnant animals, accompanied by increased choline-phosphotransferase activity in vitro in d21 liver microsomes. The rate of PC synthesis by PE N-methylation did not appear to change during pregnancy. Changes in composition of plasma PC species at term reflected those of newly synthesized hepatic PC. Our data suggest supply of PUFA to the developing fetal rat is the result of specific adaptations to maternal hepatic phospholipid biosynthesis rather than passive transfer from the maternal diet.
Animals↗
High-performance liquid chromatographic analysis of phospholipids from different sources with combined fluorescence and ultraviolet detection.
An isocratic high-performance liquid chromatographic (HPLC) system was developed for the separation of major phospholipid classes, i.e., phosphatidylcholine, sphingomyelin, lysophosphatidylcholine, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol, and phosphatidylserine. Phospholipids were detected with ultraviolet absorption at 205 nm and subsequent fluorescence detection. Fluorescence of the phospholipids (excitation, 340 nm; emission, 460 nm) was achieved by postcolumn formation of mixed micelles with 1,6-diphenyl-1,3,5-hexatriene. For ultraviolet absorption there were great differences depending on the saturation of phospholipid fatty acids but for fluorescence the sensitivity was almost identical for all phospholipids except phosphatidylinositol and lysophosphatidylcholine. Dipalmitoylphosphatidylcholine showed nearly no ultraviolet but good fluorescence response. Ultraviolet to fluorescence ratio was characteristic for different phospholipids and for identical phospholipids from different sources. Quantification of phosphatidylcholine and phosphatidylethanolamine with HPLC using N-monomethylphosphatidylethanolamine (dioleoyl) as an internal standard gave the same results as phospholipid phosphorus quantification after thin-layer chromatography.
Chromatography, High Pressure Liquid↗