Lipid composition of morris hepatoma 5123c,and of livers and blood plasma from host and normal rats

The lipid composition of Morris hepatoma 5123c was analyzed together with that of liver and blood plasma from both normal and tumor-bearing rats. The results showed that the liver of tumor-bearing rats contained higher amounts of glycerides, cholesteryl esters, free fatty acids and phospholipids than the liver of normal rats. In the blood plasma of tumor-bearing rats, there was an increase of free cholesterol and triglycerides; this latter difference, however, was not statistically significant. Acyl chain changes in the liver of tumor-bearing rats consisted of an increase of palmitic and oleic acids and a decrease of stearic and arachidonic acids in phosphatidylinositol. Morris hepatoma 5123c contained a lower amount of triglycerides than the livers (both host and normal) and showed a significant decrease of total phospholipids when compared to the host liver. The major acyl chain changes found in Morris hepatoma 5123c compared with both normal and host rat livers were: a) a higher percentage of arachidonic acid together with a lower proportion of palmitic acid in cholesteryl esters; b) an increase of stearic and arachidonic acids and a decrease of palmitic acid in triglycerides; and c) a higher level of palmitic and oleic acids associated with a lower percentage of stearic and C₂₂ polyunsaturated acids in phosphatidylcholine.     

Lipid profiles of plasma lipoproteins of fasted and fed normal and choline-deficient rats

Three major density classes of lipoproteins and a residual protein (d>1.21) were isolated by ultracentrifugation from plasma of fasted, fed normal, and choline-deficient rats. Lipid extracts were obtained from total plasma and the various density classes of lipoproteins, and each extract was examined in detail by thin layer and gas chromatographies. The results indicated essentially identical compositions of molecular species of phosphatidyl choline, which suggested their rapid equilibration among the different plasma lipoprotein classes. In contrast, the molecular species of the triacylglycerols and cholesteryl esters showed significant differences among the chylomicrons, very low and low, and high density lipoproteins, which excluded the possibility of their ready equilibration in vivo. Omission of choline from diet resulted in a sharp and statistically significant decrease in all lipid components of the very low and low density lipoproteins within 2 days. After 10 days of choline deficiency, the lipid levels of chylomicrons and very low and low density lipoproteins were ca. one-half the levels found in the choline supplemented animals, and there were discernible distortions in their lipid composition. Reintroduction of choline led to a prompt return to normal levels and lipid composition of both chylomicron and very low and low density lipoprotein fractions. The lack of equilibration of the triacylglycerols among the lipoprotein classes under normal conditions and in choline deficiency demonstrates an as yet unrecognized source of compartmentation of plasma lipids.     

Lipid composition of normal and hypertrophic bovine thyroids

The phospholipid content of bovine thyroid tissue amounts to 70% of total lipid. Triglycerides and cholesterol are the main neutral lipids. Only trace amounts of free fatty acid and esterified cholesterol are found, while two not yet identified components also are present. The distribution of lipid phosphorus in the different phospholipid classes is as follows: phosphatidyl choline, 43.0%; phosphatidyl ethanolamine, 25.2%; phosphatidyl serine, 5.6%; phosphatidyl inositol, 6.5%; sphingomyelin, 14.0%; cardiolipin, 2.8%; lysophosphatidyl choline, <1%; and phosphatidic acid, <1%. The phosphatidyl ethanolamines are rich in plasmalogens. The fatty acid patterns in the different lipid classes are reported. The essential differences between normal and hypertrophic bovine thyroid tissue are higher water content and lower triglyceride and sphingomyelin values for hypertrophic tissue.     

Lipid composition of normal male rat islets

Lipid composition was studied in fresh isolated isolets from normal male rats. Extractable lipids represent 1856 μg per mg islet protein. In such extracts, phospholipids and neutral lipids reprsent 13.5% and 86.5%, respectively. Phosphatidylcholine (45.8%) and phosphatidyl-ethanolamine (20.6%) were the major components of the phospholipid fraction, and phosphatidylinositol (8.9%) was the minor component. Esterified cholesterol (38.5%), cholesterol (25.5%) and free fatty acids (24.4%) were the major components of the neutral lipid fraction. Fatty major components of the neutral lipid fraction. Fatty acids esterified to phospholipids account for 619.7 pmol/islet, and, 2710 pmol/islet were esterified to neutral lipids. In the phospholipid fraction, saturated and unsaturated fatty acids were in a similar proportion. Conversely, in the neutral lipids, two-thirds of the fatty acids were unsaturated. The ω6 family was the main component of the phospholipid unsaturated fatty acids. In the ω6 and ω3 families, the long-chain fatty acids represent the main components. In the neutral lipid fraction, a different percentage of each family was found: ω3>ω6>ω9. The long-chain polyunsaturated fatty acids were also predominant species in the ω6 and ω3 families. Further studies on the lipid composition of islets, obtained from rats with normal and altered islet functions, could provide new insights into the knowledge of the mechanism of insulin secretion.     

Lipid composition of hepatocyte plasma membranes from geese overfed with corn

Twelve-week-old Landes male geese were overfed with corn for 21 d in order to induce liver steatosis (fatty liver). Lipid composition of hepatocyte plasma membranes from fatty livers was compared to that of lean livers obtained from geese fed a normal diet. The ratio cholesterol/phospholipids was higher in fatty hepatocyte plasma membranes (0.63 vs. 0.47), whereas the phospholipid/protein ratio was less than half. Overfeeding induced changes in fatty acid composition of hepatocyte plasma membranes, including a greater than twofold increase in the percentage of oleic acid (29.7 vs. 13.8%) and a somewhat lesser increase in lauric, palmitic, and palmitoleic acid contents of plasma membrane lipids of fatty livers. A concomitant reduction in the proportion of stearic acid (18.4 vs. 25.1%) was also observed. In fatty livers, the increased ratio of saturated to polyunsaturated fatty acids (PUFA) (1.5 vs. 1.0) was related to a significant decrease in PUFA content. Among all the PUFA, only the eicosatrienoic acid (20∶3n−9) percentage was increased by liver steatosis. Overfeeding with corn appeared to induce competition between de novo synthesized and dietary fatty acids incorporated in hepatocyte plasma membranes. This resulted in an accumulation of de novo synthesized monounsaturated and derived fatty acids in plasma membranes from overfed birds. A defect in the incorporation of linoleic acid and linoleic- and linolenic-derived PUFA was observed despite the high proportion of these essential fatty acids in the diet. It was conclued that in overfed palmipeds, de novo hepatic lipogenesis prevails over dietary lipid intake to modulate lipid composition of the fatty liver plasma membrane.     

Lipid binding in mitochondria from testes of normal and essential fatty acid deficient rats

Essential fatty acid (EFA) deficiency in rat causes severe degeneration of spermatogenic tissue. Previously it was shown that the distribution of lipid classes changes very little during tissue degeneration. However it is well known that the fatty acid spectrum in lipids from testicular tissue is altered drastically during EFA deficiency. The molecular binding of lipids in membrane structures might be altered when a larger amount of ω9-acids is present in the various lipid classes in testes of EFA-deficient rats. In the present studies comparison was made of the binding of lipids in testicular mitochondrial membranes from rats fed a fat-free diet or a diet containing 6% peanut oil for 26 weeks. Isolated mitochondria were coated on glass beads, then dried and packed into a column, whereafter the membrane lipids were eluted with solvents with increasing dielectric constants. The differences between the binding of lipid classes in supplemented and EFA-deficient rats were not pronounced, but a tendency to a weaker binding in the EFA-deficient rats was observed. However for both groups the various extracts showed marked differences in the distribution of lipid classes concurrent with the change of the eluent. This indicates a different kind of binding in the membrane, not only for different lipid classes, but also within a special lipid class. Thus both phosphatidylcholines (PC) and phosphatidylethanolamines (PE) were found in extracts with quite different dielectric constants. The fatty acid composition of PC and PE in the major fractions eluted with chloroform and ethanol, respectively, was essentially the same. This indicates that the successive release of phospholipids (PL) in these two fractions was not based on fatty acid solubility properties but on variable binding in the membrane structure. The introduction of ω9-polyenoic fatty acids instead of ω6-polyenoic fatty acids in the PL of mitochondria membranes from EFA-deficient rats seems to be the only deviation in the lipid pattern of EFA-supplemented and EFA-deficient animals, and might therefore be responsible for the symptons of EFA deficiency. Presented in part at the AOCS-ISF World Congress, Chicago, September, 1970.     

Lipid composition of liver mitochondria and microsomes in hyperthyroid rats

Triiodothyronine-induced alteration of the lipid pattern in rat-liver mitochondria and microsomes has been investigated. In mitochondria, a 25% total cholesterol decrease and a 14% phospholipid increase have been detected. In these hyperthyroid rat liver organelles, a strong decrease in the total cholesterol/phospholipid molar ratio occurs. On the contrary, in microsomes from the same animals, a decrease of about 23% has been measured for both total cholesterol and phospholipids; hence, in this fraction, the total cholesterol/phospholipid molar ratio is unaffected by hyperthyroidism. The liver mitochondrial phospholipid composition, unlike the microsomal composition, is altered significantly in hyperthyroid rats; a 7.4% phosphatidylcholine decrease is accompanied by a similar additive percentage increase of both phosphatidylethanolamine and cardiolipin. In regard to total phospholipid fatty acid composition in liver microsomes from hyperthyroid rats, no variation has been observed compared with the control rats, whereas in mitochondria from the same animals, a meaningful linoleic acid decrease with a similar arachidonic acid increase has been found. In addition to fatty acid alteration, the separated mitochondrial phospholipid classes also exhibit some increase in stearic acid. Among phospholipids, cardiolipin changes the most of the esterified fatty acids in hyperthyroid rat liver. In this compound, a strong increase in the percentage of both palmitic and stearic acid and a 32.4% decrease of linoleic acid have been found.     

Stereospecific analysis of hepatoma,host liver,and normal rat liver triglycerides from animals on chow and fat free diets

Triglycerides from normal liver, host liver, and hepatoma of rats maintained on chow and fat-free diets were subjected to stereospecific analysis. Normal and host liver triglycerides from animals on the same diet did not exhibit significant differences. Fat-free diet reduced polyunsaturated fatty acids in normal and host liver triglycerides, but had no effect upon hepatoma triglycerides. Each position of hepatoma and liver triglyceride glycerol exhibited a characteristic fatty acid composition. Palmitate concentrations were reduced dramatically and stearate levels were increased significantly at the 1 position of hepatoma triglycerides, relative to the corresponding position of liver triglycerides which were affected little by diet or tumor. Except for higher percentages of C-20 and higher fatty acids, common to all three positions, the composition of hepatoma triglycerides at the 2 position appeared normal. The 3 position of hepatoma triglycerides contained significantly higher percentages of stearate than liver. Data obtained previously for Ehrlich ascites cell triglycerides were in good agreement with this hepatoma. Data from these two neoplasms suggest that the metabolic system that regulates or controls the fatty acid composition at the 1 and 3 positions of normal tissue triglycerides does not function normally in neoplasms.     

Postnatal changes in the phospholipid composition of livers from young lambs

The total lipids were extracted from the livers of newborn lambs, from the livers of lambs during the first week after birth and from the livers of adult sheep. After separation from the nonphospholipids on columns of silicic acid the phospholipids were analyzed by thin layer chromatography and quantitative gas liquid chromatography. In all samples phosphatidyl choline and phosphatidyl ethanolamine together accounted for about 80% of the total liver phospholipids. The phosphatidyl choline-phosphatidyl ethanolamine ratio in the livers of the newborn lambs was markedly less than the ratio in the livers of the adult sheep. Moreover there was a pronounced increase in the phosphatidyl cholinephosphatidyl ethanolamine ratio in the livers of the lambs during the first week after birth. In the liver phospholipids of the lambs the concentration of phosphatidyl inositol was lower and the concentrations of phosphatidyl serine and sphingomyelin were greater than the corresponding concentrations in the liver phospholipids of the adult sheep. It is proposed that the change in the phosphatidyl choline-phosphatidyl ethanolamine ratio in the livers of the lambs during the first week after birth is due, at least in part, to the marked change that occurs in the linoleic acid-arachidonic acid ratio in the tissues of the lamb during this period.     

Differences in the long chain (sphingoid) base composition of sphingomyelin from rats bearing Morris hepatoma 7777

The long chain bases of sphingomyelin from Morris hepatoma 7777 and host and control livers were analyzed by capillary gas liquid chromatography. Sphingosine (18∶1) was the major long chain base of control livers (66.5%) and hepatomas (65.6%), but hepatomas also had a high percentage (9.3 vs 4.4) of the 16∶1 homolog. Host liver had the most unusual long chain base composition, with ca. equal 16∶1 (24.4%) and 18∶1 (21.4%) and high amounts of 20-carbon bases (9.2% 20∶0 and 15.3% 20∶1). These differences may be related to the aberrant fatty acid metabolism known to occur in tumor-bearing animals. Such large perturbations in the long chain base composition of hepatic sphingomyelin are unprecedented and could have a major impact on the properties of host membranes.     

Lipid composition of subcellular membranes from larvae and prepupae ofDrosophila melanogaster

Subcellular membranes were analyzed for their lipid composition and protein content at two developmental points representing the third instar wandering larvae and prepupal stages ofDrosophila. At both stages, phosphatidylethanolamine (PE) and phosphatidylcholine (PC) were the major constituents with phosphatidylinositol (PI), phosphatidylserine (PS), diphosphatidylglycerol (DPG) and phosphatidic acid (PA) being relatively minor components. In total homogenates and in the nuclear-enriched fraction there was no significant difference in the phospholipid composition of the wandering larvae and prepupae. In mitochondria only a significant increase in the minor component PS was observed in the prepupae. In lysosomal membranes on the other hand, the relative abundance of the major components PE and PC increased in the prepupae although the molar ratios of the two lipids remained almost constant. The fatty acid composition of the phospholipids remained virtually unchanged in all of the fractions examined, including the lysosomes, and there was no evidence of lipid peroxidation. With regard to cellular degeneration and the involvement of lysosomes, we conclude that mechanisms other than gross modification of the lipid and/or lipid/protein ratio of their membranes are involved in the liberation of the acid phosphatase contents.     

Lipid and fatty acid composition is altered in plaque tissue from multiple sclerosis brain compared with normal brain white matter

Plaques and white matter from brains of multiple sclerosis (MS) patients were analyzed for lipid content, class composition, and fatty acid composition of total lipid, together with the fatty acid composition of plaque glycerophospholipids, and the results were compared with white matter from normal brain. Plaques contained less than 30% of the lipid present in normal white matter. Plaque lipid was characterized by significantly increased proportions of glycerophospholipids and decreased cerebrosides and sulfatides. In addition, a subacute plaque contained approximately 10 times the proportion of steryl esters observed in chronic plaques or normal white matter. Total lipid from all the MS plaques showed significantly increased percentages of saturated fatty acids, n−6, n−3 and total polyunsaturated fatty acids and decreased percentages of monoenes and alk-1-enyl ethers in comparison with normal brains. These results were consistent with increased cellularity and astrogliosis associated with MS plaques. However, analysis of plaque glycerophospholipids showed that the fatty acid changes observed in total lipid were not simply due to the increased proportion of glycerophospholipids and decreased myelin lipids, but that the fatty acid composition of the individual glycerophospholipids was different.     

Volume-dependent transfer of free fatty acids from ehrlich ascites carcinoma to host tissues

The recovery of [9.10-³H] palmitate complexed to mouse serum albumin was studied 5 sec after ip injection into mice bearing Ehrlich ascites carcinomas. Only about 55% of the injected radioactivity remained in the tumor cells, tumor extracellular fluid and peritoneal washings in mice having ca. 5 ml of the ascites tumor (cells plus extracellular fluid). However the recoveries were nearly quantitative from tumors of larger volume (≥8 ml). A model is proposed to account for the volume-dependent transfer of palmitate from tumor to host in these cancerous mice. P.M. was the recipient of a fellowship from the Fonds National Suisse de la Recherche Scientifique during this study.     

Lipid composition of ten edible seed species from North Vietnam

The lipid composition and oil content of ten edible seed species from North Vietnam(Cassia tora, Ipomoea aquatica, Raphanus sativus, Citrullus lanatus, Cucumis melo, Cucurbita pepo, Luffa cylindrica, Phaseolus vulgaris, Vigna aurea, Sesamum orientale) have been investigated. The contents of hydrocarbon, triacylglycerol, free fatty acid, sterol, di- and monoglycerol, and polar lipid fractions have been determined with a thin-layer chromatography (TLC)/flame-ionization detection analyzer. Molecular species of hydrogenated triacylglycerols and the fatty acid composition of total lipids also have been analyzed by capillary gas-liquid chromatography. The quantities of major phospholipid classes of four seed species(C. tora, I. aquatica, R. sativus, V. aurea) have been determined by two-dimensional TLC and the spectrophotometrical phosphorus analysis. The fatty acid compositions of nonpolar and polar lipid fractions of these four species also have been analyzed.     

Lipid composition of the placenta of rats with protein restriction and deficiency of essential fatty acids

The influence of diet restriction and EFA deficiency during pregnancy in the rat on the lipid and phospholipids composition of the placenta was investigated. Female virgin albino Wistar rats weighing 130 +/- 4 g, were assigned to three equivalent groups. Prior mating and during pregnancy each group of rats received the following regimen: Animals in the Control Group (C) were fed a 25% casein diet in ad libitum quantities; the dietary Restricted Group (D) received the same control diet in amounts calculated to approximate 50% (g/100 g rat) of the intake of group C; the Deficient and Restricted Group (DD) rats were fed a restricted amount of EFA deficient diet. On the 21st day of gestation pregnant animals were sacrificed. The foetuses and placentae obtained by caesarium section were isolated and weighed. A 50% food restriction before and during pregnancy resulted in a significant decrease in phospholipid contents (p less than 0.05); severe EFA deficiency superimposed to 50% food restriction, moreover induced significant changes in the fatty acid pattern of phospholipids, decreasing n3 and n6 fatty acids and increasing eicosatrienoic acid. There was an accumulation of triglycerides in the placenta of rats fed on the EFA deficient diet. In the two restricted groups fetal weight was reduced, but although in the DD group, placental weight was not affected, litter size was dramatically reduced.     

Lipid composition of the sponge Verongia aerophoba from the Canary Islands

The fatty acid composition of the lipids from the sponge Verongia aerophoba was investigated and 60 acids were identified. Two of them were new and their structures were elucidated by gas chromatography‐mass spectrometry. These acids were identified as 20‐methylhexacosanoic and Δ5, 9, 22‐nonacosatrienoic. Only 13 sterols were present, and aplysterol predominated. In the volatile fraction 13 compounds were identified, mainly fatty acids, their esters and hydrocarbons, while in the n‐butanol fraction we found mainly free fatty acids and free amino acids.     

Reduction in medium chain acids and monoenoic acids in livers and plasma of rats fed eicosa-5,8,11,14-tetraynoic acid

Male Sprague-Dawley rats were fed for 8 weeks a corn oil (CO) diet or a hydrogenated coconut oil (HCNO) diet. These diets were fed in the absence or presence of eicosa-5,8,11,14-tetraynoic acid (TYA). The inclusion of TYA in the HCNO diet reduced the levels of 12∶0 and 14∶0 in the total fatty acids of livers and plasma. With either diet, the presence of TYA caused an alteration in the fatty acid composition of these tissues so as to reduce the values of the ratios: 16∶1/16∶0, 18∶1/18∶0, and 20∶4/18∶2. These results suggest that dietary TYA can influence the hepatic metabolism of medium chain fatty acids and that it may inhibit the desaturase enzyme involved in the synthesis of not only 20∶4 but also of monoenoic fatty acids.     

The effect of elaidic acid incorporation upon the lipid composition of ehrlich ascites tumor cells and of the host’s liver

The incorporation of elaidic acid into Ehrlich ascites tumor cells (EATC) upon feeding the host an elaidic acid-rich diet has been investigated in the present study. The EATC lipids contained only one-half the concentration of elaidic acid found in the lipids of either the host livers or of livers from normal mice. On the other hand, elaidic acid incorporation into tumor cells was close to that of ascites fluid. This incorporation was mainly into phospholipids; the highest into choline phospholipids and ethanolamine phospholipids. Some changes in the EATC fatty acid composition were noted due to this incorporation. EATC phospholipids had reduced polyunsaturated fatty acids as compared with oleic acid-grown cells. The same was true with respect to ascites fluid phospholipids, but neutral lipids were not altered. Tumor development was accompanied by an increase in elaidic acid of the host’s liver. Elaidic acid incorporation into tumor cells resulted in a reduction in the amount of all major lipids in the tumor. In contrast, elaidic acid had no effect on lipid composition of livers from normal mice and-tumor bearing mice, and also had no effect upon the lipids of the ascites fluid that bathes the tumor cells. The incorporation of elaidic acid into the lipids of EATC, normal liver and host liver did not affect the relative composition of phospholipids in these tissues. The development of the tumor did result in decreases in triacylglycerols and esterified cholesterol, and increases in phospholipids and free cholesterol in the livers of host animals.     

Lipid and fatty acid composition of different fractions from rat urinary transitional epithelium

The phospholipid composition of rat urinary transitional epithelium (TE) and the fatty acid composition of microsomal, mitochondrial, cytosolic, and plasma membrane (PM) subcellular fractions were investigated. PM marker enzymes and electron microscopy analysis were used to characterize the PM fraction, which showed a distinctive lipid composition compared to the general profile of PM from different sources. The levels of cholesterol and sphingomyelin were not enriched in the PM fraction; on the other hand, the increased amounts of glycosphingolipids and phosphatidylserine, and the decreased level of phosphatidylcholine followed the general features of a PM profile. This differential PM lipid composition may reflect the unique morphology of this mammal TE, consisting of concave plaques with an asymmetrical membrane unit. The distribution of the double bond across the PM indicated a higher unsaturation of the inner relative to the outer part of the PM hemileaflet. In addition, the presence of 20∶3n−9 nonessential fatty acid in a normal TE may represent a characteristic fatty acid metabolism of this epithelium. The authors wish to dedicate this work to the memory of the late Professors Benito Monis, who participated in the generation of this research and whose working hypothesis remains a source of fruitful inspiration.     

Lipid composition and biosynthesis of human omental tissue

Two groups of five males each were selected for total lipid analyses of their omental tissue. One of these groups had been subjected to a severe caloric restriction and had undergone total weight reduction of about 20%. The other group served as control. Both of these groups of patients required elective surgical procedures during which it was possible to obtain small samples of omental tissue, adipose pad, and/or mesenteric tissue. Total lipid analyses were performed on all of the materials. A distinctive positional distribution of the acyl groups was maintained in the triglycerides of omental tissue for all the patients regardless of dietary state. Patients under caloric restriction showed a reduction in their total triglyceride content, a reduction in their content of unsaturated fatty acyl groups, and a relative increase in phospholipid content. The de novo lipid biosynthetic capacity of omental tissues, as determined by 1-[¹⁴C]-acetate incorporation, showed an inverse proportionality to the lipid content of the samples. Omental tissue is biosynthetically a very versatile material capable of yielding rapidly many types of fatty acids. This ability, among others, could account for the usefulness of omental tissue as a supporting base in many types of restorative surgery.