bluuebunny/crossref_metadata_2025_split huggingface dataset:
Plasma membrane phospholipid, cholesterol and fatty acyl composition of differentiated and undifferentiated L6 myoblasts
Authors: Perkins Roger G. , Scott Robert E. 
Published: November 2006

AbstractThe lipid composition of plasma membranes isolated from differentialted and undifferentiated L6 myoblasts has been compared. In general, the plasma membranes of differentiated L6 myoblasts have a higher cholesterol to phospholipid molar ratio than plasma membranes of undifferentiated cells. Differentiated L6 myoblasts have increased relative amounts of phosphatidylethanolamine and phosphatidylcholine in their plasma membrane and a decreased relative amount of sphingomyelin when compared with the plasma membranes of undifferentiated myoblasts. In addition, preliminary results show that differentiated L6 myoblasts plasma membrane phospholipid shows differences in the fatty acyl composition, specifically there appears to be relatively more 17∶0 and 24∶1 and less 16∶1 and 18∶1 than in plasma membrane phospholipids of undifferentiated L6 myoblasts. These observations indicate that significant changes in plasma membrane lipid composition occur during myoblast differentiation. The role that changes in lipid composition play in control of cellular differentiation, however, remains to be elucidated.
Differences in the phospholipid, cholesterol, and fatty acyl composition of 3T3 and SV3T3 plasma membranes
Authors: Perkins Roger G. , Scott Robert E. 
Published: November 2006

AbstractAn analysis of the phospholipid, cholesterol, and phospholipid fatty acyl composition of isolated plasma membranes of 3T3 and SV3T3 mouse embryo cells has been performed. The results show that the plasma membrane of SV3T3 cells contain relatively less phosphatidylethanolamine and sphingomyelin and more cholesterol than 3T3 plasma membranes. The fatty acyl composition of individual phospholipid classes as determined by gas liquid chromatography also showed differences between 3T3 and SV3T3 plasma membranes. The plasma membranes of SV40 transformed 3T3 cells contain: (a) a higher percentage of 18∶1 and less 20∶3 and 20∶4 in phosphatidylethanolamine; (b) a higher percentage of 18∶1 in phosphatidylserine; and (c) a higher percentage of 18∶2 and 20∶4 in phosphatidylinositol.
The interaction of 1,25‐dihydroxyvitamin D3 with its intestinal mucosa receptor: Kinetic parameters and structural requirements
Authors: Putkey John A. , Wecksler Wayne R. , Norman Anthony W. 
Published: November 2006

AbstractVitamin D3 and its metabolites comprise an endocrine system which plays a critical role in calcium homeostasis. The active form of vitamin D3 is 1,25‐dihydroxyvitamin D3 [1,25(OH)2D3]. Chromatin localization of 1,25(OH)2D3 and sucrose density gradient centrifutation have demonstrated the presence of an intestinal mucosa cytosol receptor which specifically binds 1,25(OH)2D3. The kinetic parameters of 1,25(OH)2D3 binding to its receptor have been determined by hydroxylapatite and reconstituted chromatin cytosol assays. Utilization of these assays has also permitted a determination of the precise structural requirements of the vitamin D ligand for the intestinal receptor. Furthermore, it has been possible to propose two receptor‐ligand models which are capable of accommodating the conformationaly modile A ring of the vitamin D seco‐steroids.
Brain mitochondrial incorporation of elongated fatty acids into phospholipids
Authors: Moss S. A. , Yatsu F. M. 
Published: November 2006

AbstractThe characteristics patterns and asymmetric distribution of phospholipid fatty acids suggest precise control mechanisms. Our investigations were designed to assess mitochondrial fatty acid elongation and their pattern of incorporation into complex lipids. Fatty acid chain elongation in the total lipid fraction occurred primarily with the more abundant fatty acids present. Elongation patterns in free fatty acids were similar to the total lipid fraction except C20:4 and C22:4 were formed to slightly greater extent. Choline glycerophosphatide and ethanolamine glycerophosphatide displayed different patterns of elongation. Choline glycerophosphatide contained more elongated longer chain polyunsaturated fatty acids, while ethanolamine glycerophosphatide contained greater amounts of elongated shorter chain saturated and monounsaturated fatty acids. These results suggest that fatty acid elongation may play a specific role in fulfilling mitochondrial phospholipid fatty acid requirements.
Lipids of cultured hepatoma cells: V. Distribution of isomeric monoene fatty acids in individual lipid classes
Authors: Wood Randall , Falch John , Wiegand Rex D. 
Published: November 2006

AbstractMonoenoic acid fractions were isolated from phosphatidylcholines, phosphatidylethanolamines, triglycerides, and cholesterol esters derived from minimal deviation hepatoma 7288C cells cultured on 11 media containing varying levels of serums and lipids. Hexadecenoate (16∶1), octadecenoate (18∶1), and eicosenoate (20∶1) fractions were subjected to ozonolysis and the isomeric composition of the monoene fractions determined quantitatively by gas liquid chromatography. The 16∶1 fractions consisted of palmitoleic acid, the Δ9 isomer (85–90%), and the Δ11 isomer (10–15%) in most of the cases; growth media and lipid class origin had little effect upon composition. The predominate acids of the 20∶1 fraction were the Δ13 and Δ11 isomers. Generally, the Δ13 isomer was present in the highest concentration, and this isomer was higher in phosphatidylcholines than the other classes. Vaccenic acid represented 33–66% of the 18∶1 fraction, and the balance was oleic acid. Oleic acid concentrations decreased, and vaccenic acid levels increased as the growth medium serum and lipid levels decreased. Lipid classes did not exhibit any distinct preference for either isomer. These data represent the first quantitative isomeric analysis of monoenoic acids derived from individual lipid classes and are the first to show the occurrence of high levels of vaccenic acid in neoplastic cells. This study suggests that the elevated levels of oleic acid, one of the most frequently observed changes in tumor lipids, may, in fact, represent elevated levels of vaccenic acid.
Changes in phospholipid composition in hibernating ground squirrel,Citellis lateralis, and their relationships to membrane function at reduced temperatures
Authors: Aloia Roland C. , Pengelley Eric T. , Bolen James L. , Rouser George 
Published: November 2006

AbstractThe hearts of hibernating mammals have the capacity to function at reduced temperatures of 1 C in contrast to hearts of nonhibernating mammals which undergo ventricular fibrillation during deep hypothermia. Thus, all vital membrane functions continue in hibernators. This suggests that there may be special features of their lipid and protein composition. Analysis of the hearts of the hibernating ground squirrel,Citellus lateralis, in the active (37 C) and hibernating state (1–4 C) reveals differences in the percent composition of the phospholipid classes. There is a decrease in the percentage of diacyl choline, ethanolamine, serine phosphoglycerides, and diphosphatidyl glycerol and an increase in the percentage of lysophosphatidyl choline, lysophosphatidyl ethanolamine, lysodiphosphatidyl glycerol, and phosphatidic acid in the hibernating state. There is also an increase in the molar amount of phosphorus/100 g fresh wt of tissue during hibernation. The most striking difference in phospholipid composition between active and hibernating heart tissue is the 3.5‐fold increase in lysoglycerophosphatides. These compounds are implicated as contributing factors controlling membrane fluidity during hibernation and upon which the physiological state of hibernation may be contingent.
New series of fatty acids in Northern Pike (Esox lucius)
Authors: Glass R. L. , Krick Thomas P. , Eckhardt Allen E. 
Published: November 2006

AbstractThe presence in Northern Pike (Esox locius) liver and testes lipids of a group of eight homologous fatty acids of as yet unknown structure is reported. They occur esterified to cholesterol and to glycerol as triglycerides but are absent from the phospholipids. They contain three oxygens and are characterized further by being more resistant to hydrogenation than normal unsaturated fatty acids and by an inability to form urea inclusion compounds. They also have been found to be major constituents of the liver fatty acids of four additional species of fish.
Metabolism of 2,4‐3H‐14α‐methyl‐5α‐ergost‐8‐enol and 2,4‐3H‐5α‐ergosta‐8,14‐dienol inChlorella ellipsoidea
Authors: Tsai L. B. , Patterson G. W. , Cohen C. F. , Klein P. D. 
Published: November 2006

Abstract5α‐Ergosta‐8,14‐dienol and 14α‐methyl‐5α‐ergost‐8‐enol were synthesized chemically from ergosterol and labeled with tritium at the C‐2 and C‐4 positions. Both labeled sterols, when incubated with growing cultures ofChlorella ellipsoidea, were converted to ergost‐5‐enol but not to C‐27 or C‐29 sterols.Chlorella ellipsoidea, thus, has the capability of removing the C‐14 methyl group and converting the 8(9) and 8,14 double bond systems to the 5(6) position. Brassicasterol produced by this organism is not labeled in these experiments, indicating that it is not derived from a saturated side chain precusor.
Transport of diacylalkylglycerols in chylomicrons and very low density lipoproteins of rat intestinal lymph following intragastric administration of 1,3‐dioctadecenoyl‐2‐hexadecylglycerol
Authors: Pitas R. E. , Hagerty M. M. , Jensen R. G. 
Published: November 2006

AbstractThe triacylglycerol (TG) analog 1,3‐dioctadecenoyl‐2‐hexadecyl glycerol was used in the study of the transport of dietary lipids by lipoprotein fractions of rat intestinal lymph. 1,3‐Diacyl‐2‐alkyl glycerols (DAG) are hydrolyzed by pancreatic lipase to form 2‐alkyl glycerols and free fatty acids. These hydrolysis products are then absorbed, and DAG are resynthesized within the intestinal mucosa. Intestinal lymph of rats was collected following intragastric administration of 1,3‐dioctadecenoyl‐2‐hexadecyl glycerol. The DAG to TG ratios in very low density lipoprotein (VLDL) and chylomicron fractions were determined as a measure of the incorporation of lipid of dietary origin. The ratio of DAG to TG in the VLDL‐2 (Sf 12–100) fraction ranged from0.06 to 0.56 indicating a significant amount of DAG transported relative to TG. The glyceryl ether to TG ratio increased with mean lipoprotein volume from the VLDL‐2 fraction to the chylomicron (Sf>400) fraction. The correlation between glyceryl ether to TG ratio and average volume and between the amount of DAG per ml of original lymph and average volume within the chylomicron fraction was 0.99. Thus, the amount of dietary fat transported was correlated with the size of the chylomicrons produced. The glyceryl ether to TG ratio was positively correlated with the average volume of the lipoprotein fractions isolated (chylomicrons, chylomicron rich (Sf>100), VLDL‐1 (Sf 100–400) and VLDL‐2) (r=0.87). These results suggest that the size of the lipoproteins produced by the intestine is determined by the amount of fat available for transport and that particles of larger diameter are formed by the addition of lipid of dietary origin to existing VLDL.
Distinctive medium chain wax esters, triglycerides, and diacyl glyceryl ethers in the head fats of the pacific beaked whale,Berardius bairdi
Authors: Litchfield Carter , Greenberg Anne J. , Ackman R. G. , Eaton C. A. 
Published: November 2006

AbstractLipids were extracted from the mandibular fat body (jaw), the fatty forehead (melon), and the dorsal blubber of a Pacific beaked whale (Berardius bairdi) and separated into lipid classes by preparative thin layer chromatography. The head fats were mixtures of wax esters and triglycerides with a very small amount of diacyl glyceryl ether. The blubber fat contained 97% was ester and 3% triglyceride. Gas liquid chromatography (GLC) of the intact lipid classes indicated an unusually low C26–C30 range for most of the jaw and melon wax esters compared to the more normal C32–C40 molecules found in the blubber. Distinctive lower molecular weight C24–C40 triglycerides occurred in the head fats vs. the usual C44–C58 range in the blubber. Most diacyl glyceryl ethers were in the C35–C46 range, below the molecular weight of hexadecyldipalmitoyl glyceryl ether (C48). GLC of the derived fatty acid methyl esters showed that the lower molecular weight neutral lipids in the head fats were due to high levels of iso‐10∶0, n−10∶0, iso‐11∶0, iso‐12∶0, n−12∶0, and iso‐13∶0 acids. The wax ester fatty alcohols and the alkoxy chains of the glyceryl ethers were mostly the C14–C20 chain lengths commonly observed in marine organisms. The distinctive medium chain neutral lipids in the jaw and melon fats of this whale may be related to the postulated acoustical role of these tissues in echolocation.
Selective effects of fatty acids upon cell growth and metabolic regulation
Authors: Lands William E. M. , Sacks Roger W. , Sauter John , Gunstone Frank 
Published: November 2006

AbstractPositional isomers ofcis‐methyleneoctadecanoic acid differed greatly in their efficiency for growth of an unsaturated fatty acid auxotroph ofEscherichia coli upon glucose as a carbon source. The 8, 9, and 11 isomers were more efficient in producing cells (60–70 cells/fmole) than the others (0–7 cells/fmole), although all isomers were found esterified to a similar extent into cellular lipid. WithSaccharomyces cerevisiae mutants, all isomers between 6 and 12 supported some growth of the eukaryotic cells, and the 7 and 9 isomers were slightly more efficient than the 8‐isomer. WhenE. coli were grown with glycerol, all isomers from 5 to 14 supported growth, and those with the substituent near the center of the acyl chain had the greatest efficiency (70 cells/fmole). With the glycerol medium, the pattern of efficiencies for the variouscis‐methylene acyl chains resembled the broad selectivity reported earlier for thecis‐ethylenic isomers in glucose medium, which agreed closely with predictions based upon the physical property of their phospholipid derivatives. Thus, metabolism of glycerol appeared to allow the cyclopropane acyl chains to support cell functions to the limits expected for bulk phase chain‐chain fluidity considerations. This broad specificity was also obtained when cells were grown on glucose with cyclic AMP added to the culture. Therefore, the selective inadequacies of the 5, 6, 7, 10, 12 and 13 isomers in supporting cell growth on glucose may occur through an interaction modified by cAMP and dependent upon reduced cellular levels of cyclic AMP. The highly selective pattern of efficiency of thecis‐methylene acids forE. coli growth on glucose resembles that with the acetylenic acids, but was shifted one carbon atom toward the methyl terminus. This observed selectivity pattern seems due to interactions of the individual acyl chains with cellular protein(s) rather than to chain‐chain interactions in a bulk phase. The ability of certain positional isomers to support cell function equally well in both nutrient conditions suggests that the role of those acyl chain isomers may be independent of metabolite flux or cyclic nucleotide contents of the cell, whereas the actions of other isomeric fatty acids seem closely related to the metabolic status of the cell. A highly selective role for different fatty acids in modulating cellular function seems possible on the basis of the current evidence.
The evidence for the antiatherogenicity of high density lipoprotein in man
Authors: Miller N. E. 
Published: November 2006

AbstractIt has long been recognized that patients with clinical coronary heart disease (CHD) have, on average, higher concentrations of plasma very low density and low density lipoproteins than do healthy subjects. The same, studies clearly demonstrated that coronary victims tend also to have low plasma concentrations of high density lipoprotein (HDL). It is only recently, however, that the possible significance of this second observation has been examined. Direct evidence for an inverse relationship between HDL cholesterol concentration and the prevalence of clinical CHD, independent of other plasma lipoproteins, has been provided by the Honolulu Heart and Cooperative Lipoprotein Phenotyping Studies. The Tromsø Heart and Framingham Studies subsequently demonstrated that this relationship precedes the clinical manifestation of coronary disease. More recently, angiographic studies have confirmed that the severity of existing coronary atherosclerosis is inversely related to HDL cholesterol concentration. Other investigations have shown that coronary victims also have low mean concentrations of apolipoproteins AI and AII (the major protein components of HDL), although the reduction of apoAI concentration may be less marked than that of HDL cholesterol, and preliminary findings from Tromsø have suggested that apolipoprotein AI may be less powerful than HDL cholesterol as a predictor of CHD. Such observations have supported the proposal that HDL may exert a protective effect against coronary atherosclerosis. Final confirmation (or otherwise) of this hypothesis, however, must await the results of carefully controlled animal experiments and of regression studies in patients with angiographically defined atherosclerosis.
Ultrastructure of serum high density lipoproteins: Facts and models
Authors: Scanu Angelo M. 
Published: November 2006

AbstractThe complexity of the structure of plasma high density lipoproteins (HDL) has invited numerous approaches which have been directed at the study of the intact particles, their apolipoproteins and reassembled complexes. Parameters such as flotation and sedimentation coefficients, size and molecular weight have been determined and in addition, through scattering techniques, an understanding has been obtained on the long range organization between core (cholesteryl esters and triglycerides) and surface components (unesterified cholesterol, phospholipids and apoproteins). In the case of the apolipoproteins, the knowledge of their primary structure has facilitated the study of their physicochemical properties in solution and at the air‐water interface and has also permitted realistic predictions of the two dimensional organization, not only of their α‐helical segments but also of the β‐pleated sheets, random coil and β‐turns, all of which have amphipathic properties. When all of the information from the physical and chemical studies is put together, the various HDL can be described as spherical structures having a liquid core of radius, r—20.2 Å, surrounded by a monolayer of cholesterol and phospholipids with closely packed hydrophobic ends on the surface of the core. The organization of the apoproteins at the lipoprotein interface is comparatively less understood. However, reasonable predictions can be made on secondary structure considerations and on their behavior at the air‐water interface. The emerging overall structural information can be translated into a space‐filling model that not only provides a useful visual representation of HDL, but, more importantly, a basis for planning future studies on the elucidation of the structure of these particles on a molecular level.
Quantitation of high density lipoproteins
Authors: Albers John J. , Warnick G. Russell , Chenng Marian C. 
Published: November 2006

AbstractThe demand for high density lipoprotein (HDL) quantitation has dramatically increased with the renewed awareness of the importance of HDL as a negative risk factor for coronary heart disease. HDL is usually estimated by specific precipitation of the non‐HDL apoB‐containing lipoproteins by polyanions and divalent cations followed by measurement of cholesterol in the supernatant. A common procedure involves precipitation with sodium heparin at 1.3 mg/ml and MnCl2 at 0.046 M (final concentrations). This method is appropriate for serum but less than ideal for plasma because of incomplete precipitation and sedimentation of the apoB‐containing lipoproteins. A two‐fold increase in Mn2+ to 0.096 M improves precipitation of the apoB‐associated lipoproteins from plasma without excessive precipitation of HDL. This modified heparin‐Mn2+ procedure gives results nearly identical to the results with the ultracentrifugal reference method (cholesterol in the d>1.063 fraction corrected for losses and the presence of apoB‐associated cholesterol). The dextran sulfate 500‐Mg2+ and the sodium phosphotungstate‐Mg2+ procedures give results consistently 2–4 mg/dl lower than does the reference method. In contrast, a heparin‐Ca2+ method gives results 5–8 mg/dl higher than does the reference method. Immunochemical analysis of apoA‐I in the precipitate and apoB in the supernatant indicates that lower values for the phosphotungstate‐Mg2+ procedure is due to partial precipitation of the A‐I‐containing lipoproteins, while higher values by the heparin‐Ca2+ method are due to incomplete precipitation of the apoB‐containing lipoproteins. Quantitation of the principal apoproteins of HDL, A‐I and A‐II, represent an important additional index of HDL concentrations and composition. Quantitation of plasma A‐I and A‐II concentrations by radial immunodiffusion indicates that women generally have higher HDL concentrations than men (women, A‐I, 135±25, A‐II, 36±6; men, A‐I, 120±20, A‐II, 33±5; mean±S.D., in mg/dl). A‐I and A‐II do not increase with age in men but show a slight increase with age in women. Estrogen increases HDL cholesterol and protein and may in part account for the higher HDL in women. The lighter density HDL subclass has a higher A‐I/A‐II ratio than the denser HDL subclass, with women generally having significantly more of the lighter HDL subclass. Density‐gradient ultracentrifugation in CsCl2 gradients indicates that HDL contains subpopulations of differing hydrated density which vary in the A‐I/A=II ratio. Immunoassay of A‐I and A‐II when used in combination with HDL cholesterol analysis is a powerful tool for studies of HDL structure, epidemiology and metabolism.
Fatty acid biosynthesis in the developing endosperm ofCocos nucifera
Authors: Oo K. C. , Stumpf P. K. 
Published: November 2006

AbstractEndosperm tissue of developing coconut endosperm incorporated [14C] acetate and [14C]‐malonate into [14C]C8‐C18 fatty acids. The distribution of [14C] label into the various fatty acids mimicked the distribution of endogenous fatty acids at early and middle stages of endosperm development. Although [14C] C8‐C18 fatty acids were taken up rapidly by endosperm tissue slices, no elongation occurred; [14C] stearic acid was not desaturated to oleic. Cell free preparations have also been obtained from this tissue that readily incorporated [14C] malonyl‐CoA into a range of [14C] fatty acids in the presence of ACP and NADH at pH 7.0. Employing this system, a number of experiments were designed to determine the mechanism of chain length termination. In contrast to intact tissue slice experiments, cell‐free extracts yielded as principal products palmitic and stearic acid, although up to 20% were shorter chain acids. A number of possible mechanisms for chain length termination were proposed and tested.
Composition of lipids bound to pure cytochrome P‐450 of cholesterol side‐chain cleavage enzyme from bovine adrenocortical mitochondria
Authors: Hall P. F. , Watanuk M. , Degroot J. , Rouser G. 
Published: November 2006

AbstractPhospholipids bound to highly purified cytochrome P‐450 from bovine adrenocortical mitochondria, part of the enzyme complex responsible for catalyzing the conversion of cholesterol to pregnenolone, have been examined for comparison with the bulk phospholipids of the mitochondria from the same tissue. In both cases, the major phospholipids are phosphatidylcholine (PC) (37%) and phosphatidylethanolamine (PE) (56%), as well as smaller amounts of sphingomyelin and diphosphatidylglycerol. The fatty acid compositions of the four classes of phospholipids and of the neutral lipids bound to the pure enzyme are indistinguishable from those of the respective mitochondrial lipids. They are also similar to those of mitochondria from other organs except for high levels of arachidonate and low levels of diphosphatidylglycerol.