bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phosphatidylcholine as the choline donor in sphingomyelin synthesis
Authors: Eppler C. Mark , Malewicz Barbara , Jenkin Howard M. , Baumann Wolfgang J. 
Published: November 2006

AbstractSphingomyelin synthesis was studied in cultured Novikoff rat hepatoma cells by following transfer of [14C]choline label into sphingomyelin (SPH). The study was facilitated by the fact that prelabeling of the cells with [Methyl‐14C]choline resulted in rapid accumulation of essentially all the label (≈95%) in phosphatidylcholine (PC). The redistribution of PC label during a 15‐hr chase was dependent upon the extracellular choline concentration. Under conditions of free choline diffusion (500 μM choline), loss of lable from PC was most pronounced, and the percentage of total radioactivity that became trapped in the extracellular water‐soluble choline pool was an order of magnitude greater than in low choline medium (27 μM choline). Despite the significant loss of water‐soluble label from the cells in high choline medium, SPH labeling proceeded at essentially the same rate at either choline concentration. During the label chase in 500 μM choline, the specific radioactivity of PC decreased, but the specific radioactivity of SPH continued to increase for 9–12 hr until it reached the specific radioactivity of PC. In the presence of 300 μM neophenoxine (NPO), transfer of label from PC into SPH was stimulated. NPO also decreased the specific radioactivity of PC to about the same extent as that of SPH was increased. Because transfer of choline label from PC to SPH was not affected by loss or dilution of water‐soluble precursors, and because the specific radioactivity of PC and SPH, in the absence or presence of NPO, responded in a characteristic precursor product fashion, we conclude that sphingomyelin synthesis in Novikoff cells circumvents the water‐soluble choline pool and that phosphatidylcholine serves as the immediate choline source. All our data support the phosphatidylcholine:ceramide cholinephosphotransferase pathway of sphingomyelin synthesis.
Characteristics of phospholipids in human lung carcinoma
Authors: Nakamura Mitsushige , Onodera Tsugutami , Akino Toyoaki 
Published: November 2006

AbstractHuman lung carcinoma tissues with histological types of adenocarcinoma, squamous cell and small cell carcinoma were investigated for phospholipids. There were marked differences in the phospholipids between these lung carcinoma and normal lung tissue. A marked decrease in saturated phosphatidylcholine (PC), predominantly the dipalmitoyl species, was noted in the carcinoma, although they still contained 17–20% of the saturated classes. The lung carcinoma contained less phosphatidylglycerol (PG) and lyso‐bis‐phosphatidic acid and more cardiolipin and phosphatidylinositol (PI) than the normal lung tissue. These alterations observed in the lung carcinoma apppeared to show that they lose the characteristic feature of phospholipids in the lung tissue. The differences in the lipid composition among different cell types of lung carcinoma were also noted. The squamous cell and small cell carcinoma contained more triacylglycerol and relatively higher dienes I (monoenoic‐monoenoic) and lower dienes II (saturated‐dienoic) of PG, respectively, as compared to adenocarcinoma.
Comparative studies on composition of cardiac phospholipids in rats fed different vegetable oils
Authors: Kramer J. K. G. 
Published: November 2006

AbstractMale Sprague‐Dawley rats were fed diets for 1 or 16 weeks, containing 20% by weight vegetable oils differing widely in their oleic, linoleic and linolenic acid content. No significant changes were observed in the level of the cardiac lipid classes. The fatty acid composition of the 2 major phospholipids, phosphatidylcholine and phosphatidylethanolamine, showed a remarkable similarity between diets in the concentration of total saturated, C22 polyunsaturated and arachidonic acids. Monounsaturated acids were incorporated depending on their dietary concentration, but the increases were moderate. Dietary linolenic acid rapidly substituted C22 polyunsaturated fatty acids of the linoleic acid family (n−6) with those from the linolenic acid family (n−3). The results suggest that dietary linolenic acid of less than 15% does not inhibit the conversion of linoleic to arachidonic acid but the subsequent conversion of arachidonic acid to the C22 polyunsaturates was greatly reduced. Significant amounts of dietary monounsaturated fatty acids were incorporated into cardiac cardiolipin accompanied by increases in polyunsaturated fatty acids, apparently to maintain an average of 2 double bonds/molecule. The cardiac sphingomyelins also accumulated monounsaturated fatty acids depending on the dietary concentration. It is quite evident from the results of this study that the incorporation of oleic acid and the substitution of linolenic for linoleic acid‐derived C22 polyunsaturated fatty acids into cardiac phospholipids was related to the dietary concentration of these fatty acids and was not peculiar to any specific oil. Even though it is impossible to estimate the effect of such changes in cardiac phospholipids on membrane structure and function, results are discussed which suggest that the resultant membrane in the Sprague‐Dawley male rat is more fragile, leading to greater cellular breakdown and focal necrosis.
Dinosterol in model membranes: Fluorescence polarization studies
Authors: Harel Zvi , Djerassi Carl 
Published: November 2006

AbstractThe interaction between the phospholipids ofCrypthecodinium cohnii, a heterotropic marine dinoflagellate, and its major sterol dinosterol was studied using a fluorescence polarization technique. Compared to cholesterol, dinosterol is less soluble in model membranes and as effective in increasing the microviscosity. These results indicate that the unique side chain of dinosterol does not play a special role in terms of complementary interaction with the phospholipids of this organism.
Selective reactions in the analysis and characterization of steroids by gas chromatography‐mass spectrometry
Authors: Brooks C. J. W. , Cole W. J. , McIntyre H. B. , Smith A. G. 
Published: November 2006

AbstractGas chromatography‐mass spectrometry (GC‐MS) is a technique especially suitable for the analysis and characterization of steroids, and its power has been extensively demonstrated. The efficacy of GC‐MS is limited, nevertheless, by the fact that steroid mixtures—whether of natural origin only, or augmented by synthetic analogs—often contain similar components that are poorly distinguished. The fortuitous overlap of gas chromatographic peaks from disparate compounds also impairs the definition of retention data. Controlled modification of the sample by means of selective reactions is therefore a valuable adjunct to the application of GC‐MS. Two examples are discussed: (a) the enzyme cholesterol oxidase, isolated from various microorganisms, catalyzes the oxidation of many 3β‐hydroxy‐5‐enes (with concomitant isomerization) to 4‐en‐3‐ones; 3β‐hydroxy‐5α‐steroids are also oxidized to the corresponding 3‐ones, but other steroids (3α‐hydroxy‐ or 5β‐isomers, etc.) are unaffected. The mild conditions required (pH 7, 30 C) are advantageous for the analysis of sensitive steroids, and the retention index increments, as well as the mass spectra of the ketones, are characteristic. The enzyme accepts as substrates a wide range of 3β‐hydroxysteroids, tolerating oxygenation in ring B and even catalyzing the oxidation of 2‐oxacholesterol to the expected lactone; and (b) steroids possessing 1,2‐diol or 1,3‐diol groupings include estriols, 2‐hydroxyestrone, 20,22‐dihydroxycholesterols, ecdysones, brassinolide and many corticosteroids. The selective formation of cyclic derivatives can provide several analytically useful features, such as convenient retention times, moderate mass increments (24 amu for a methaneboronate), distinctive mass spectra and usually abundant molecular ions. These are exemplified for 5‐pregnene‐3β‐20,21‐triols and for 20,22‐dihydroxycholesterol as well as its enzymic oxidation product.
Abnormal suppression of 3‐hydroxy‐3‐methylglutaryl‐CoA reductase activity in cultured human fibroblasts by hypertriglyceridemic very low density lipoprotein subclasses
Authors: Gianturco Sandra H. , Packard Christopher J. , Shepherd James , Smith Louis C. , Catapano Alberico L. , Sybers Harley D. , Gotto Antonio M. 
Published: November 2006

AbstractOur previous studies showed that hypertriglyceridemic very low density lipoproteins (HTG VLDL) are functionally abnormal. HTG VLDL, but not normal VLDL, suppress HMG‐CoA reductase in cultured normal human fibroblasts. To determine if the suppression by HTG VLDL resulted from a subpopulation of smaller suppressive particles, more homogeneous subclasses of VLDL‐VLDL1 (Sf 100–400), VLDL2 (Sf 60–100), and VLDL3 (Sf 20–60) were obtained from the d<1.006 (g°ml−1) fraction of normal and hypertriglyceridemic plasma by flotation through a discontinuous salt gradient and tested for suppression in normal human fibroblasts. VLDL1 and VLDL2 from each of the 12 normolipemic subjects tested failed to suppress HMG‐CoA reductase activity in normal fibroblasts. Eleven out of 12 preparations of normal VLDL3 suppressed HMG‐CoA reductase, but only one‐third as effectively as LDL. By contrast, the VLDL1, VLDL2 and VLDL3 from 15 out of 17 hypertriglyceridemic patients (hyperlipoproteinemia Types IIb, III, IV and V) were highly effective in suppression, with half‐maximal suppression at 0.1–2.0 μg VLDL protein/ml. The VLDL abnormality is apparently associated with hypertriglyceridemia and not hypercholesterolemia, since VLDL from a homozygous familial hypercholesterolemia patient with a Type IIa pattern did not suppress whereas each of the VLDL subclasses from a Type IIb patient suppressed. Suppression by HTG VLDL in normal cells is apparently a consequence of interaction of the protein portion of the VLDL with the specific LDL cell surface receptor since HTG VLDL1 treated with 0.1 M 1,2‐cyclohexanedione to block arginyl residues failed to suppress the enzyme. Moreover, hypertriglyceridemic Sf 60–400 VLDL failed to suppress HMG‐CoA reductase activity in LDL receptor‐negative fibroblasts. There were no consistent major compositional differences between comparable normal and hypertriglyceridemic VLDL subclasses which could account for differences in suppression. All VLDL subclasses from Type III subjects were enriched in cholesteryl esters and depleted in triglyceride, relative to the corresponding normal VLDL subclasses. However, Type IV and Type V VLDL subclasses were normal in this repect. We conclude from these studies that small particle diameter is not required for suppression, since HTG VLDL1 and VLDL2 which contained few, if any, small particles were effective in suppression.
Formation of 12‐[18O]Oxo‐cis‐10,cis‐15‐phytodienoic acid from 13‐[18O]hydroperoxylinolenic acid by hydroperoxide cyclase
Authors: Vick Brady A. , Feng Paul , Zimmerman Don C. 
Published: November 2006

Abstract13‐[18O] Hydroperoxylinolenic acid was permitted to react with an extract of flaxseed acetone powder containing hydroperoxide cyclase activity. The resulting product, 12‐oxo‐cis‐10,cis‐15‐phytodienoic acid (12‐oxo‐PDA), contained18O in the carbonyl oxygen at carbon 12, suggesting that an epoxide was an intermediate in the hyderoperoxide cyclase reaction. A substrate specificity study showed that acis double bond β,γ to the conjugated hydroperoxide group was essential for the substrate to be converted to a cyclic product by hydroperoxide cyclase.
A simple chromatographic method for purification of egg lecithin
Authors: Riis Nielsen Jørn 
Published: November 2006

AbstractEgg lecithin was purified from the CdCl2‐lecithin complex by column chromatography on Alumina. The yield from 5 eggs was 2.8 g. The purified lecithin had correct chemical values for pure lecithin and a fatty acid composition similar to lecithin prepared by other methods. The method probably can be adapted for purification of other lipids containing the phosphocholine moiety and for purification of synthetic lecithin.
Sterol and fatty acid composition of the clam,Codakia orbicularis, with chemoautotrophic symbionts
Authors: Berg Carl J. , Krzynowek Judith , Alatalo Philip , Wiggin Kate 
Published: November 2006

AbstractCodakia orbicularis may obtain nutrients from chemoautolithotrophic bacteria. The chemical composition of theC. orbicularis was investigated because of this unusual source of nutrition, and because it is a human food source in the Caribbean. The lipid fraction of these molluscs is discussed in detail. Polyunsaturated fatty acids account for only 11–15% of the total fatty acids, and non‐methylene interrupted dienes are present as high as 9.5%. Cholesterol represents about 45% of the total sterols present.
Tocopherol‐phospholipid liposomes: Maximum content and stability to serum proteins
Authors: Halks‐Miller Meredith , Guo Luke S. S. , Hamilton Robert L. 
Published: November 2006

AbstractThis study addresses two questions: 1) what is the maximum amount of tocopherol that can be contained in egg phosphatidylcholine liposomes, and 2) what is the stability of these vesicles in the presence of serum proteins? These liposomes, made with a French pressure cell, can contain no more than 33 mol % of tocopherol. Tocopherol changes liposomes in a manner similar to cholesterol, making them larger, less permeable to aqueous dyes and highly resistant to protein‐induced disruption. The suppression of protein‐induced disruption is more pronounced with tocopherol than with cholesterol, even at lower molar ratios. Thus, liposomes containing alpha tocopherol (15 to 30 mol%) may be useful for delivering physiological quantities of this vitamin to cells in culture or to tissues in vivo.
High performance liquid chromatographic separation of diacylglycerol acetates to quantitate disaturated species of lung phosphatidylcholine
Authors: Itoh Kiyoharu , Suzuki Akira , Kuroki Yoshio , Akino Toyoaki 
Published: November 2006

AbstractA high‐performance liquid chromatographic (HPLC) separation of diacylglycerol acetates to quantitatite disaturated species of lung phosphatidylcholine (PC) was studied. The diacylglycerol acetates were applied on a reversed phase column, eluted by an isocratic solvent, acetonitrile/isopropanol/water (35:15:1, v/v/v) at a flow rate of 1 ml/min, and detected by differential refractometry (RI). This isocratic HPLC method was useful to separate disaturated species from the others of lung PC.The quantitative analysis of the molecular species separated by HPLC was studied by RI detection. Chroamtograms obtained by RI detection and radioactivity determination of diacylglycerol [3H]acetates prepared by [3H]acetic anhydride were almost identical. The RI detector responsed in the same degree for different, authentic standards of diacylglycerol acetates. The detection limit with RI detection was about 30 nmoles. Molecular species of PCs from human lung and carcinoma tissues were analyzed by this HPLC method. The contents of disaturated species were very similar to those reported previously. These results indicate that RI detection is very useful in the nmole range for the quantitative analysis among the molecular species containing disaturated species.
Modification of epoxidized soybean oil for lubricant formulations with improved oxidative stability and low pour point
Authors: Hwang Hong‐Sik , Erhan Sevim Z. 
Published: November 2006

AbstractTo produce soybean oil‐based lubricants with good oxidative stability and low pour point, epoxidized soybean oil (SBO) was chemically modified. Epoxidized SBO was reacted with various alcohols in the presence of sulfuric acid as a catalyst to give a ring‐opened intermediate product. In this step, the epoxy group was transformed to the functional group of‐CH(OR1)CH(OH)‐(where the R1=methyl, 1‐butyl, 2‐butyl, 1‐hexyl, cyclohexyl, 2,2‐dimethyl‐1‐propyl, or 1‐decyl). The 1H nuclear magnetic resonance spectra of the products indicated that transesterification was accompanied by the ringopening reaction except when the bulky 2,2‐dimethyl‐1‐propanol was used. Acid anhydride was used to esterify the hydroxy groups in the ring‐opened product. This resulted in a fluid that is a lubricant candidate with the functional group of −CH(OR1)CH(OCOR2)−. Pour point studies of the resulting products showed that the pour points varied with the substituents, R1 and R2. Products with R1=CH3(CH2)5− and R2=CH3(CH2)2−, (CH3)2CH−, or CH3(CH2)4‐showed the lowest pour points (−39, −39, and −45°C, respectively) when 1% of pour point depressant was added. For the oxidative stability test, two products, in which R1, R2=CH3(CH2)5−, (CH3)2CH− and R1, R2=CH3(CH2)5−, CH3(CH2)4−, were chosen for a modified Penn State micro‐oxidation test. In the oxidative stability test, the products gave 69–71% of oxidative evaporation and 10–17% of tetrahydrofuran‐insoluble deposits in 3 h at 175°C. The amounts of deposits were much lower than those of soybean oil (96%) and epoxidized SBO (83%) and even less than those of most petroleum‐based lubricant basestocks (3–93%).
Characterization of dihydroxystearic acid from palm oleic acid
Authors: Awang R. , Ahmad S. , Kang Y. B. , Ismail R. 
Published: November 2006

AbstractDihydroxystearic acid (DHSA) was prepared from palm oleic acid and characterized by chromatographic and spectroscopic methods (gas chromatography, thin‐layer chromatography, Fourier transform infrared and nuclear magnetic resonance spectroscopy) as well as wet chemistry. The crude product has a melting point of 62°C, acid value of 179, saponification value of 178, and hydroxyl value of 196. The yield was about 90% based on unsaturation. The product obtained was found to contain DHSA, saturated fatty acids, and unknown products. DHSA is soluble in alcohol, and its solubility decreased by increasing the alcohol chain length. An irritancy test of DHSA indicated that purified DHSA is nonirritating.
Simultaneous determination of lipophilic aldehydes by high‐performance liquid chromatography in vegetable oil
Authors: Seppanen C. M. , Csallany A. Saari 
Published: November 2006

AbstractA very sensitive high‐performance liquid chromatography (HPLC) method was developed for the simultaneous separation and measurement of nonpolar and polar lipophilic secondary lipid peroxidation products in vegetable oil. Seventeen nonpolar and 13 polar lipophilic aldehydes and related carbonyl compounds, derived from thermally oxidized soybean oil as 2,4‐dinitrophenyl hydrazones, were separated simultaneously by reversed‐phase HPLC. Detection limit for the individual compounds is 1 ng. Thirteen of the nonpolar carbonyl compounds were identified as: butanal, 2‐butanone, pentanal, 2‐pentanone, hexenal, hexanal, 2,4‐heptadienal, 2‐heptenal, octanal, 2‐nonenal, 2,4‐decadienal, decanal, and undecanal. Three of the polar carbonyl compounds were identified as: 4‐hydroxy‐2‐hexenal, 4‐hydroxy‐2‐octenal, and 4‐hydroxy‐2‐nonenal. The detection of the toxic 4‐hydroxy‐2‐nonenal, a major compound, and 4‐hydroxy‐2‐hexenal, a minor compound, in heated soybean oil is of particular importance because these toxic compounds have been shown to be absorbed from the diet.
Trans, saturated, and unsaturated fat in foods in the united states prior to mandatory trans‐fat labeling
Authors: Satchithanandam Subramaniam , Oles Carolyn J. , Spease Carol J. , Brandt Mary M. , Yurawecz Martin P. , Rader Jeanne I. 
Published: November 2006

AbstractOn July 11, 2003, the U.S. Food and Drug Administration published a final rule amending its food‐labeling regulations to require that trans FA be declared in the nutrition label of conventional foods and dietary supplements. The effective date of this final rule is January 1, 2006. This places some urgency on increasing the number and types of currently available foods for which there are trans‐fat data. Compositional databases on trans fat content of food are currently limited. The purpose of this study was to determine the trans‐fat content of a wide range of foods prior to the effective date of the new regulation. AOAC Official Method of Analysis 996.01 was modified for the analysis of trans fat in noncereal products. Food products for analysis were selected on the basis of market share and data from the USDA's 1994–1996 Continuing Survey of Food Intake by Individuals. Foods were purchased from local supermarkets, weighed, hydrolyzed, converted to FAME, and analyzed by GC. The results showed that trans fat (g/100 g fat) ranged from 0.0 to 48.8 in bread, cake, and related products; from 14.9 to 27.7 in margarines; from 7.7 to 35.3 in cookies and crackers; from 24.7 to 38.2 in frozen potatoes; from 0.0 to 17.1 in salty snacks; from 0.0 to 13.2 in vegetable oils and shortenings; from 0.0 to 2.2 in salad dressings and mayonnaises; and from 0.0 to 2.0 in dry breakfast cereals. Serving sizes for the foods included in this survey ranged from 12 to 161 g, and trans‐fat levels ranged from 0.0 to 7.2 g/serving. The significant differences in trans‐fat content in products within each food category are due to differences in the type of fats and oils used in the manufacturing processes.
Validation of a single‐isotope‐labeled cholesterol tracer approach for measuring human cholesterol absorption
Authors: Wang Yanwen , Vanstone Catherine A. , Parsons William D. , Jones Peter J. H. 
Published: November 2006

AbstractCholesterol absorption is frequently determined using the plasma dual stable‐isotope ratio method (PDSIRM). However, this method involves intravenous injection of stableisotope‐labeled cholesterol with simultaneous oral administration of differently labeled cholesterol, which results in high study costs and involves additional ethical considerations. The objective of the present study was to validate a simpler singleisotope method for determining cholesterol absorption against PDSIRM by using data from two previous studies. Enrichments of carbon‐13 (13C) and deuterium in red blood cells were analyzed by using differential isotope ratio MS. The area under the curve of 13C‐enrichment in the plasma free‐cholesterol pool was found to be significantly correlated with cholesterol absorption measured by using PDSIRM for study 1 (r=0.85, P<0.0001) and study 2 (r=0.81, P<0.0001). Average 13C‐enrichment correlated with the area under the curve of 13C‐enrichment in the plasma free cholesterol for both study 1 (r=0.98, P<0.0001) and study 2 (r=1.00, P<0.0001). Study 1 examined the efficacy and mechanisms of unesterified plant sterols and stanols on lipid profiles in hypercholesterolemic men and women, while study 2 investigated the effects of phytosterol vs. phytostanol esters on plasma lipid levels and cholesterol kinetics in hyperlipidemic men. Experimental approaches to determine cholesterol absorption were identical between the two studies. Consequently, in both studies, correlations (r=0.88, P<0.0001 for study 1, and r=0.82, P<0.0001 for study 2) were found between the average 13C‐enrichment of plasma free cholesterol and cholesterol absorption measured by PDSIRM. These results suggest that a single‐isotope‐labeled cholesterol tracer approach can be used as a reliable noninvasive method to replace PDSIRM for examining changes in cholesterol absorption.