Uptake of [14C] choline and incorporation into lung phospholipid by the isolated perfused rat lung

We have used the isolated perfused lung (IPL) preparation from the rat to determine whether uptake of choline from the vascular compartment could limit the rate of synthesis of phosphatidylcholine (PC). The uptake of choline was rapid and did not saturate at a concentration of 10 mM. The rate of incorporation of choline into phospholipid was saturated above 0.1 mM choline. Whereas, uptake and incorporation were depressed at 4 C, uptake was neither dependent on the extracellular sodium concentration nor inhibited by equimolar concentrations of hemicholinium-3 (HC-3). We could find no evidence that uptake might limit synthesis of lung lecithin and conclude that uptake is either by free diffusion, or by a carrier-mediated process with a very high Km.     

Biosynthesis of sex pheromone components and glycerolipid precursors from sodium [1-14C]acetate in redbanded leafroller moth

Sodium [1-¹⁴C]acetate in water-dimethyl sulfoxide (11) was applied topically to sex pheromone glands ofArgyrolaenia velutinana. Radiolabel was incorporated into the pheromone components (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate, and also into triacylglycerols, diacylglycerols, ethanolamine phosphatides, and choline phosphatides. In the triacylglycerols, radiolabel appeared in (Z)-11-tetradecenoate, (E)-11-tetradecenoate, tetradecanoate, hexadecanoate, and octadecanoate. In the choline phosphatides, the same acyl moieties incorporated radiolabel but at lower levels. In the diacylglycerols and ethanolamine phosphatides, only the radiolabel in hexadecanoate and octadecanoate was above the limit of detection. At different times following application of sodium [1-¹⁴C]acetate, the relative proportions of labeled (Z)-11-tetradecenyl acetate and (E)-11-tetradecenyl acetate changed very little, but the relative proportions of labeled fatty acyl moieties in the triacylglycerols and choline phosphatides changed markedly. After 8 min, triacylglycerols had incorporated about equal amounts of radiolabel into (Z)-11-tetradecenoate, (E)-11-tetradecenoate, and tetradecanoate. As the incubation time was increased, triacylglycerols accumulated proportionately more radiolabeled (E)-11-tetradecenoate than (Z)-11-tetradecenoate, and accumulated proportionately less radiolabeled tetradecanoate. In the choline phosphatides, at all times of incubation the amount of radiolabel incorporated into (Z)-11-tetradecenoate was small but above the limit of detection, and the amounts of radiolabel in (E)-11-tetradecenoate and tetradecanoate were smaller and often below the limit of detection. In both the triacylglycerols and the choline phosphatides, the relative proportion of radiolabeled hexadecanoate decreased with time, and that of octadecanoate increased.     

In vitro incorporation of acetate-1-14C into the phospholipids of rabbit and human endometria

Endometria from nonpregnant and 6-day pregnant rabbits and from humans in the proliferative and secretory phases were incubated with 1-¹⁴C-acetate.¹⁴CO₂ was collected, and subsequently the amounts, specific radioactivities, and in some cases the fatty acid compositions of the isolated phospholipids were determined. Phosphatidyl choline was the phospholipid present in highest amount in endometria from both nonpregnant and pregnant rabbits, and in human endometria; this phospholipid also showed the highest degree of incorporation of¹⁴C-acetate. Pregnancy in the rabbit seemed to decrease the incorporation of¹⁴C-acetate into most of the endometrial phospholipid classes. In humans, the incorporation of acetate into phosphatidyl choline and phosphatidyl ethanolamine was lower in the secretory than the proliferative endometria. Of the fatty acids, linoleic acid in phosphatidyl choline and phosphatidyl ethanolamine of the rabbit endometria showed a significant relative increase during pregnancy and palmitoleic acid showed a decrease. This investigation was supported by a grant from the Ford Foundation.     

Methylating activity of (Methyl-14C)-S-adenosylmethionine by microsomes of the insectCeratitis capitata

The methylating activity of (methyl-14C)-S-adenosylmethionine by microsomes from different stages of development of the insect Ceratitis capitata was studied in a series of in vitro experiments. Larval and pharate adult microsomal preparations were used in the in vitro conditions, and the utilization of the methyl group of the S-adenosylmethionine for the synthesis of phospholipids was evaluated. Incorporation of radioactivity in lipids by pharate adult microsomes was significantly higher than that by larval preparations. In both cases, phosphatidyl ethanolamine showed the highest levels of radioactivity incorporation. Free bases from total lipid hydrolysates were resolved by paper chromatography, and the labeling was investigated by radioactivity scanning of paper chromatograms. Larval and pharate adult preparations showed clearly the presence of dimethylethanolamine and choline. The presence in the incubation media of phosphatidyldimethylethanolamine and deoxycholate enhanced the radioactivity incorporation into choline, whereas, the first stages of methylation were inhibited. These findings confirmed previous results using insect homogenates.     

Synthesis and property of hydrogel membranes consisting of fumaramate with phosphorylcholine group

Fumaramate bearing a phosphoryl choline group, isopropyl‐2‐[2′‐(trimethylammonium) ethyl phosphoryl] ethyl fumaramate (IPTPFA), was radically copolymerized with 2‐hydroxyethylmethacrylate (HEMA) in the presence of various crosslinking agents, water, and 2,2′‐azobis(isobutyronitrile) to obtain hydrogel membranes. The obtained hydrogel membranes adsorbed bovine serum albumin (BSA) much less than those of poly(HEMA), and the values of water content (H) were higher than those of poly(HEMA). The values of tensile strength and tensile elongation of the hydrogel were 68.4 g/mm² and 239%, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 2552–2557, 2004     

Effect of chlorphentermine on incorporation of [14C]choline in the rat lung phospholipids

The effect of chlorphentermine (CP) treatment (50 mg/kg/ day, per os [po]) on the incorporation of [¹⁴C]choline into rat lung phospholipid was studied.Total phospholipid content was increased 2.0-fold and 1.7-fold after seven and 14 days, respectively, compared with the pair-fed rats. The incorporation of [¹⁴C]choline into phosphatidylcholine (PC) was significantly inhibited by either seven or 14 days of CP treatment. Nevertheless, the PC content was significantly increased by day 7 and stayed elevated at day 14 of CP treatment. Choline and phosphorylcholine contents were significantly decreased by the CP treatment. These results suggest that the higher accumulation of PC is due to inhibition of enzymes involved in the hydrolysis of phospholipids rather than to a stimulation of the phospholipid synthesis. Presented in part at the SOT Meeting, Atlanta, GA, March 1984 (abstracted inThe Toxicologist 4[1], 64).     

Metabolism of 1-14C linolenic acid in developing brain: II. Incorporation of radioactivity from 1-14C linolenate into brain lipids

Metabolism of 1-¹⁴C linolenic acid was studied in growing animals by injecting the tracer intraperitoneally into 12–13 day old suckling rats and following up the results by sacrificing groups of animals at 8 hr, 48 hr, 15 day, and 45 day intervals. In the first 15 days, there was a greater decrease in radioactivity of brain total lipids compared to the later period, although the earlier age period is characterized by lipid deposition rather than breakdown. Since the 18∶3 ω3 family of fatty acids occurs largely in the brain total phosphatidyl ethanolamine fraction, we expected that, in the initial period, total phosphatidyl ethanolamine would be the most highly radioactive component. However, results showed that 8 hr after the tracer phosphatidyl choline had the highest specific radioactivity. When the total phosphatidyl ethanolamine fraction was resolved into diacyl and alk-1-enyl species, it was found that radioactivity was not distributed evenly between the two species. There was a progressive increase in radioactivity of the alkenyl and a decrease in the diacyl species. Forty-eight hr after the tracer, however, the radioactivity of phosphatidyl ethanolamine increased and at 45 days remained slightly higher than phosphatidyl choline. Radioactivity of cholesterol, a result of synthesis from acetate undoubtedly derived from the breakdown of tracer linolenate, was also high 48 hr after tracer and remained high until 45 days.     

Differential trypsin effect upon (1-14C) acetate incorporation into choline and ethanolamine glycerophosphatides of rat brain and liver

Preincubation of rat brain and liver slices in a medium (5% glucose, 5% fructose, 1% albumin, 1% trypsin, 10 mM phosphate buffer pH 6.0) used to pretreat brain tissue for the separation of cell types was found to uncouple the incorporation of (1-¹⁴C) acetate into ethanolamine phosphoglycerides from that of the choline phosphoglycerides. Incorporation into ethanolamine phosphoglycerides was stimulated in both brain (330%) and liver (780%) slices, while the incorporation of (1-¹⁴C) acetate into choline phosphoglycerides was reduced for both brain (71%) and liver (63%) slices, compared to control values from nonpreincubated material. With (1-¹⁴C) linolenic acid as a precursor, no significant differences were found in incorporation into ethanolamine phosphoglycerides and choline phosphoglycerides.     

Synthesis, characterization and cytotoxicity of phosphoryl choline-grafted water-soluble carbon nanotubes

Carbon nanotubes (CNTs) were rendered water-soluble by grafting on phosphoryl choline (PC). The modified CNTs were characterized utilizing Fourier transform infrared spectra, X-ray photoelectron spectra, thermogravimetric analysis, nuclear magnetic resonance, transmission electron microscopy, ultraviolet/visible absorbance spectra and dynamic laser light-scattering. The results show that the target products are easily dispersed in water and remain dispersed for at least three months. This study showed that both CNTs and CNT-PC induce no cytotoxicity on clonal pheochromocytoma cells (PC12) and human colon carcinoma cell lines (Caco-2). The grafted PC group confers water solubility and keeps the cell-compatibility of CNTs.     

Alternate pathways of cerebroside catabolism

A search was made for new degradative pathways for glucosyl and galactosyl ceramides in an effort to explain the failure of these lipids to accumulate in the brains of children with Krabbe's or Gaucher's disease. Using various buffers and incubation conditions, we tested brain homogenates from 12 day old rats with the stearate-labeled and galactose-labeled lipids. No evidence for direct deacylation (and formation of psychosines) could be obtained, nor was there any evidence for transacylation of sphingocyl phosphoryl choline or oxidation of the 6 position of the galactose moiety. Two new derivatives of galactosyl ceramide were observed, possibly fatty acid esters of unknown polar compounds. It is tentatively proposed that the etiology of infantile Krabbe's and Gaucher's diseases involves, not an accumulation of galactosyl and glucosyl ceramides, with consequent formation of toxic products, but rather malfunction of some other role of the corresponding glycosidases.     

Synthesis and characterization of TiO2 nanoparticles chemically coated with zwitterionic polymer brushes

This study introduces a synthetic method to graft zwitterionic poly (2-methacryroyloxyethyl phosphoryl choline) brushes onto TiO₂ nanoparticles with thickness of a few nanometers. The grafting of zwitterionic polymer brushes was characterized by electron microscope measurements, zeta-potential analysis, and thermo-gravimetric analysis. The technique we employed to synthesize those hybrid nanoparticles was a modified seeded emulsion polymerization in which the polymerization loci were changed in the stage of radical initiation and chain propagation. We have found that the polymerization loci should be on the surface for achieving the effective grafting of polymer brushes. From the suspension rheology studies, we have observed that the suspension of our hybrid nanoparticles was dominated by the attractive force as well as by packing volume effect. This unique rheological behavior is expected to be useful for understanding the inter-particle interactions in complex formulations.     

Lipids of cultured hepatoma cells: VI. Glycerolipid and monoenoic fatty acid biosynthesis in minimal deviation hepatoma 7288C

1-14C-Acetic, 1-14C-palmitic, or 1-14C-stearic acid was incubated with minimal deviation hepatoma 7288C cells grown in culture to assess: de novo fatty acid synthesis, oxidation, desaturation, and elongation of saturated fatty acids, as well as the ability of media fatty acids to serve as precursors of cellular glycerolipids. Distribution of radioactivity in the individual lipid classes and the various fatty acids of triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine was determined. The radioactivity among the monoenoic acid isomers derived from triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine was analyzed by reductive ozonolysis. Only small amounts of the labeled substrates were oxidized to carbon dioxide. Except for labeled stearic acid, which also was incorporated heavily into phosphatidyl inositol and phosphatidyl serine, most radioactivity was recovered in triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine. Synthesis of cholesterol and long chain fatty acids from labeled acetic acid demonstrated that these cells can perform de novo synthesis of fatty acids and cholesterol. Both labeled palmitic and stearic acids were desaturated to the corresponding delta9 monoenes, and palmitic and palmitoleic acids were elongated. The nexadecenoic acid fraction isolated from triglyceride, phosphatidyl choline, and phosphatidyl ethanolamine, when acetic or palmitic acid was the labeled substrate, showed that greater than 70 percent of the labeled acids were the delta9 isomer. Radioactivity of the octadecenoic acid fraction derived from labeled acetic or palmitic acids was nearly equally divided between the delta9 isomer, oleic acid, and the delta11 isomer, vaccenic acid. Desaturation of labeled stearic acid produced only oleic acid. These data demonstrate that the biosynthesis of vaccenic acid in these cultured neoplastic cells proceeds via the elongation of palmitoleic acid. The relatively high level of vaccenic acid synthesis in these cells suggests that the reported elevation of "oleic acid" in many neoplasms may result from increased concentration of vaccenic acid.     

Labeling of liver and plasma lecithins after injection of 1–2-14C-2-dimethylaminoethanol and14C-L-methionine-methyl to choline deficient rats

Groups of rats were fed a choline-deficient (CD) or a choline-supplemented (CS) diet for 15 hr. Labeling of liver and plasma cephalins and lecithins was followed with time after injection of¹⁴C-L-methionine-methyl or 1–2-¹⁴C-2-dimethylaminoethanol, either alone or together with³H-S-adenosyl-L-methionine-methyl. A reduced concentration of liver and plasma lecithins was found in CD rats. In the same animals, labeling of the phospholipid fractions was considerably greater and faster than in CS rats. Administration of choline to rats previously fed the CD diet resulted in both an increased concentration of liver and plasma lecithins and a reduction in the labeling of liver and plasma lecithins to levels seen in control rats. These results suggest that in CD rats, while the overall synthesis of lecithins may be reduced due to insufficient availability of choline, the synthesis of lecithins via stepwise methylation of cephalins may be increased.     

一种新型无卤阻燃剂的合成研究

通过三氯氧磷与对苯二胺在～50℃反应,合成了新型的膨胀型阻燃剂磷酰三（4-氨基苯基）胺,产率95％,熔点198．8—200．6℃。阻燃对比试验表明,该产物具有较为理想的阻燃效果,经改进后可望成为有实用价值的新型膨胀型阻燃剂。     

Lipid labeling with32P-orthophosphate and14C-acetate in marine copepods

Freshly collectedCalanus pacificus were maintained in sea water containing 25 μCi/ml [³²P]orthophosphate or 1 μCi/ml [¹⁴C]acetate at 10 C for 24 hr. The animals took up label from the environment and incorporated it into various lipid fractions. After incubation with [¹⁴C]acetate the order of specific activity of the different lipid classes was: phospholipids > free fatty acids > wax esters > triglycerides. Argentation thin layer chromatography of the fatty acid methyl esters showed that ca. 50% of the activity was in saturated fatty acids and 34% in polyunsaturated acids. When the animals were exposed to [³²P]orthophosphate, lysophosphatidyl choline became most heavily labeled, followed by lysophosphatidyl ethanolamine, sphingomyelin, phosphatidyl ethanolamine, and phosphatidyl choline. Comparison of the data obtained with those available for decapods and mammals revealed striking similarities between these phylogenetically distant groups. It is believed that labeling the lipids of marine and freshwater planktonic crustaceans in this way will provide much information about the metabolism of lipids in these organisms.     

乙氧羰基烯丙基取代的肟醚类化合物的研究

采用"一锅法"来研究这一反应。由酮肟1与氢化钠作用产生酮肟阴离子2,酮肟阴离子再与α-乙氧羰基乙烯基膦酸二乙酯3作用产生膦酸酯取代的碳负离子4,该碳负离子进一步与醛作用得到α-乙氧羰基烯丙基肟醚化合物,产率在73%～79%。     

Intravenously injected [1-14C]arachidonic acid targets phospholipids, and [1-14C]palmitic acid targets neutral lipids in hearts of awake rats

The differential uptake and targeting of intravenously infused [1-¹⁴C]palmitic ([1-¹⁴C] 16∶0) and [1-¹⁴C]arachidonic ([1-¹⁴C]20∶4n−6) acids into heart lipid pools were determined in awake adult male rats. The fatty acid tracers were infused (170 μCi/kg) through the femoral vein at a constant rate of 0.4 mL/min over 5 min. At 10 min postinfusion, the rats were killed using pentobarbital. The hearts were rapidly removed, washed free of exogenous blood, and frozen in dry ice. Arterial blood was withdrawn over the course of the experiment to determine plasma radiotracer levels. Lipids were extracted from heart tissue using a two-phase system, and total radioactivity was measured in the nonvolatile aqueous and organic fractions. Both fatty acid tracers had similar plasma curves, but were differentially distributed into heart lipid compartments. The extent of [1-¹⁴C]20∶4n−6 esterification into heart phospholipids, primarily choline glycerophospholipids, was elevated 3.5-fold compared to [1-¹⁴C]16∶0. The unilateral incorporation coefficient, k ^*, which represents tissue radioactivity divided by the integrated plasma radioactivity for heart phospholipid, was sevenfold greater for [1-¹⁴C]20∶4n−6 than for [1-¹⁴C]16∶0. In contrast, [1-¹⁴C]16∶0 was esterified mainly into heart neutral lipids, primarily triacylglycerols (TG), and was also found in the nonvolatile aqueous compartment. Thus, in rat heart, [1-¹⁴C]20∶4n−6 was primarily targeted for esterification into phospholipids, while [1-¹⁴C]16∶0 was targeted for esterification into TG or metabolized into nonvolatile aqueous components.     

Phospholipid synthesis in mammary tissue. Choline and ethanolamine kinases: Kinetic evidence for two discrete active sites

Choline and ethanolamine kinases are located in the high speed supernatant of lactating bovine mammary gland. Maximum activities of choline and ethanolamine kinases were observed at pH 9.2 and 8.0, respectively, with the rate of ethanolamine phosphorylation being 1/15 that of choline phosphorylation. Activation energies of 29 joules (Q₁₀-1.5) and 31 joules (Q₁₀=1.5) were calculated between 3.4 and 31.3C for choline kinase and ethanolamine kinase, respectively. Above 31.3 C, the Arrhenius plot deviated from linearity for both enzymes, suggesting that denaturation was occurring. An apparent Km of 0.25 mM for choline was obtained for choline kinase activity. The apparent Km of ethanolamine kinase for ethanolamine was unusually high (17 mM), and activity was not linear with increasing protein concentration. Activity was tripled and the Km decreased to 2.5 mM when the enzyme preparation was washed with butanol: benzene mixture, suggesting the presence of an endogenous competitive inhibitor(s), with respect to ethanolamine. Choline kinase was not affected by the solvent wash. Substrate competition studies revealed that choline kinase was slightly inhibited competitively by ethanolamine (apparent Ki=19–21 mM), whereas choline was a potent competitive inhibitor of ethanolamine kinase (apparent Ki=0.33–0.50 mM). The results indicated that these two kinase activities were mediated by two distinct active sites, possibly on a single protein. The significance of choline in the regulation of phosphatidylethanolamine synthesis is discussed.     

Turnover of label from [1-14C] linolenic acid in phospholipids of coho salmon,Oncorhynchus kisutch

Juvenile coho salmon were injected intraperitoneally with [1-¹⁴C] linolenic acid, and sampled at 24, 120, and 240 hr. Liver, heart, and gill lipids were extracted, analyzed, and halflives of individual liver glycerophospholipids and n-3 fatty acids determined from rates of loss of radioactivity. Incorporation of label into gill was much less than into either heart or liver. Total acyl halflife was shorter for the choline phospholipids than for the ethanolamine phospholipids, as were the halflives of all individual n-3 fatty acids. Eicosapentaenoic acid (20∶5n-3) had the shortest halflife in both phospholipids (50–60 hr), while docosapentaenoic acid (22∶5n-3) and docosahexaenoic acid (22∶6n-3) had much longer halflives. Specific activities of the shorter chain n-3 fatty acids were much greater than the longer, more unsaturated homologs at all times, suggesting possible differences in their mechanisms of incorporation into phospholipids. Diacylglycerol analysis indicated that de novo synthesis could be responsible for the incorporation of only a small portion of the labeled long chain fatty acids found in phospholipids. The fatty acid halflives reported here for salmon are in general agreement with those found previously in mammals. Technical Paper No. 5238, Oregon Agricultural Experiment Station, Oregon State University, Corvallis, Oregon 97331. This material is taken in part from a thesis submitted in partial fulfillment of the requirements for the MS degree in 1978.     

三氯化铝催化C_(13)～C_(14)烯烃齐聚反应

使用三氯化铝作催化剂,对C_(13)～C_(14)内烯烃齐聚反应进行了研究,考察三氯化铝用量、反应温度和反应时间等工艺条件对聚内烯烃合成油收率的影响,确定了最佳工艺条件:三氯化铝用量为原料总质量的3%,反应温度160℃,反应时间4 h。在此条件下,以C_(13)～C_(14)内烯烃与1-十四碳烯的混合物为反应原料合成了聚烯烃合成油,并研究了其物化性能。结果表明,采用质量分数各为50%的1-十四碳烯与C_(13)～C_(14)内烯烃混合物,可以合成100℃黏度为6.10 mm~2·s~(-1)、黏度指数147和凝点-40℃的聚烯烃合成油,收率为78%,具有黏度低、凝点低和黏度指数高的特点,是高质量的聚烯烃合成油。