bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phospholipid oxidation in emulsions
Authors: Corliss G. A. , Dugan L. R. 
Published: November 2006

AbstractThe autoxidation of purified phosphatidyl ethanolamine (PE) and phosphatidyl choline (PC), extracted from egg and soybean lipids, was followed by oxygen uptake measurements in emulsified systems. All emulsified phospholipid fractions had comparable activation energies. Measurement by various physico‐chemical tests was made of specific changes in the phospholipid molecule during autoxidation. PE oxidized more rapidly and absorbed more oxygen than PC. Higher 2‐thiobarbituric acid test and diene and triene conjugation absorbance values were observed for PE than for PC. Of the two major polyunsaturated fatty acids in egg phospholipids, arachidonic acid disappeared at a more rapid rate during oxidation while the concentration of linoleic acid decreased to a level that was relatively constant. Although typical unsaturated fatty acid oxidation appeared to occur in all phospholipid fractions, oxidation in aqueous emulsions was only partly a function of fatty acid composition. The nitrogen moieties, ethanolamine and choline influenced the induction period for the oxidation of PE and PC respectively.
In vitro studies on cholesterol metabolism in the blood flukeSchistosoma mansoni
Authors: Smith Thomas M. , Brooks Thomas J. , Lockard Virginia G. 
Published: November 2006

AbstractAdultSchistosoma mansoni were axenically maintained in NCTC 109 culture media containing14C labeled acetate or mevalonate. Dibromide derivatives prepared from purified blood fluke cholesterol exhibited a lack of significant radioactivity on examination by liquid scintillation spectrometry. Autoradiographic electron microscopy of tissues from flukes maintained in the presence and absence of labeled acetate and especially fixed to retain cholesterol revealed a similar random distribution of nonspecific grains. However, when particulate labeled cholesterol was supplied, a count of 6,832 dpm was found in the dibromide derivative. Under the above maintenance conditionsS. mansoni adults do not synthesize cholesterol from acetate or mevalonate but most probably obtain this sterol from the host animal.
Uptake and release of fatty acids by rat adipose tissue: Last in—First out?
Authors: Ekstedt Bertil , Olivecrona Thomas 
Published: November 2006

AbstractFatty acid labeled chyle was administered iv to ad lib fed rats. At intervals from 1 hr to 50 days later rats were killed and pieces of their parametrial adipose tissue were incubated in vitro with norepinephrine. The specific radioactivity of the mobilized free fatty acids was compared to that of tissue glycerides and that of tissue free fatty acids. The results indicate that fatty acids taken up by the adipose tissue do not mix immediately with the bulk of tissue lipids and that the mobilized free fatty acids do not pass through the tissue free fatty acid pool.
Agents affecting lipid metabolism. XXVI. Specificity of some inhibitors of the late stages of cholesterol biosynthesis
Authors: Kraml M. , Dubuc J. , Dvornik D. 
Published: November 2006

AbstractThe capacity of 22,25‐DAC, AY‐9944 and triparanol to inhibit cholesterol biosynthesis from three precursors, mevalonate, 7‐dehydrocholesterol and desmosterol, has been studied in rat liver homogenates.Evidence is presented that, in vitro, 22,25‐DAC, a potent inhibitor of the sterol Δ24‐reductase, also inhibits the 7‐dehydrocholesterol‐Δ7‐reductase system.
The nature of the stimulatory role of the supernatant fraction on triglyceride synthesis by the α‐Glycerophosphate pathway
Authors: Johnston John M. , Rao G. Ananda , Lowe Patricia A. , Schwarz Barry E. 
Published: November 2006

AbstractEvidence is presented as to the nature and mechanism of the stimulatory effect of the supernatant fraction on the biosynthesis of triglycerides via the α‐glycerophosphate pathway in the intestinal mucosa. When microsomes are employed as the enzyme source, the major lipid formed from either labeled palmitic acid orl‐α‐glycerophosphate is phosphatidic acid and only a limited amount of triglyceride is synthesized. The addition of the supernatant fraction to microsomes results in a stimulation of triglyceride biosynthesis at the expense of phosphatidic acid. Employing the same microsomal fraction, the reaction sequence was followed step by step and the intermediates were isolated. The results suggest that the stimulatory role of the supernatant fraction can be attributed to the presence ofl‐α‐phosphatidate phosphohydrolase (EC 3.1.3.4). The hydrolysis of the biosynthesized microsomal phosphatidic acid by the supernatant enzyme occurs at a faster rate than the hydrolysis of added phosphatidic acid prepared from egg lecithin. The initial acylation steps in the biosynthesis of triglycerides or phosphatidic acid via the glycerophosphate pathway occur only in the presence of fatty acid and the cofactors necessary for its activation. Under these conditions, fatty acyl‐CoA will not substitute for the fatty acid activation system.
Interaction of calcium ions with lecithin and sphingomyelin monolayers
Authors: Shah Dinesh O. , Schulman Jack H. 
Published: November 2006

AbstractDipalmitoyl lecithin and sphingomyelin monolayers have similar limiting areas, whereas their surface potentials are strikingly different. The double bond at the 4–5 position in sphingomyelin acts as an induced dipole in relation to the surface potentials. This was confirmed by the surface potential of hydrogenated sphingomyelin. The binding of calcium to lecithin and sphingomyelin monllayers resulted in an increase in surface potential. This increase was greater for the dipalmitoyl lecithin monolayer as compared to that for sphingomyelin. It is concluded that the binding of calcium ions to springomyelin monolayers is significantly reduced by the presence of the hydroxyl group at the 3‐carbon position of the molecule.
Mechanism of lipoxidase reaction. I. Specificity of hydroperoxidation of linoleic acid
Authors: Dolev Ami , Rohwedder W. K. , Dutton H. J. 
Published: November 2006

AbstractLinoleate hydroperoxides from autoxidation of methyl linoleate and from lipoxidase oxidation of linoleic acid are compared. Data indicate an equal amount of methyl 9‐ and 13‐hydroperoxyoctadecadienoate produced by autoxidation of methyl linoleate, and the exclusive formation of 13‐hydroperoxyoctadeca‐9,11‐dienoic acid from the incubation of lipoxidase with linoleic acid. As a result of these findings, a specific mechanism for the reaction of lipoxidase with linoleic acid is postulated.
Mechanism of lipoxidase reaction. II. Origin of the oxygen incorporated into linoleate hydroperoxide
Authors: Dolev Ami , Rohwedder W. K. , Mounts T. L. , Dutton H. J. 
Published: November 2006

AbstractTwo different series of experiments were performed to establish the origin of the oxygen molecule incorporated into hydroperoxide during the incubation of lipoxidase with linoleic acid. These showed, as previously assumed but never demonstrated, that the oxygen introduced into the hydroperoxide molecules comes from the gaseous phase and not from the aqueous phase. Furthermore, soybean lipoxidase does not catalyze the exchange between gaseous oxygen and water oxygen. Possibly, lipoxidase may be involved in the biosynthesis of hydroxytrans,cis conjugated octadecadienoates present in various seeds.
Quantitative analysis of brain and spinach leaf lipids employing silicic acid column chromatography and acetone for elution of glycolipids
Authors: Rouser George , Kritchevsky Gene , Simon Gerald , Nelson Gary J. 
Published: November 2006

AbstractsQuantitative elution of acidic and neutral glycolipids of brain and spinach leaves from silicic acid columns with acetone was demonstrated. Cerebrosides and sulfatides of brain and sulfolipid and glycosyl diglycerides of spinach leaves were eluted quantitatively with acetone while prospholipids remained on the column. The observations provide the basis for an analytical procedure employing column and quantitative thin‐layer chromatography (TLC). Sephadex column chromatography is utilized for separation of lipids from nonlipids; silicic acid column chromatography for separation into neutral lipid, glycolipid and phospholipid fractions; and quantitative TLC for analysis of lipid classes of each column fraction.
Chemical composition of subcellular particles from cultured cells of human tissue
Authors: Tsao Shuang‐Shine , Cornatzer W. E. 
Published: November 2006

AbstractChemical composition of subcellular components of HeLa, KB, human heart and liver tissue‐culture cell lines have been studied.The concentration of RNA, protein and phospholipid (μg/μg of DNA) of total subcellular particles was similar for all four cell lines studied. The greatest RNA concentration and lowest protein concentration is found in the microsomes as compared to the other subcellular fractions of HeLa and KB cells.The lipid P/Protein N ratio of mitochondria was greater than the other subcellular fractions from tissue‐culture cell lines studied. Phosphatidyl choline and phosphatidyl ethanolamine are the major phospholipids with the former more predominant in all of the subcellular fractions of tissue‐culture cells studied. Phosphatidyl inositol, phosphatidyl serine, sphingomyelin and polyglycerol phosphatide were shown to be present. Phosphatidyl choline composition (per cent of total lipid‐P) is greatest in the microsomes when compared with the other subcellular fractions obtained from all of the cell lines studied except the nuclear fraction of human liver cells. Correspondingly, the mitochondrial fraction for all of the tissue culture cell lines contains the greatest composition of phosphatidyl ethanolamine except for the human liver and heart cells. The mitochondrial fraction contains the lowest amount of phosphatidyl inositol. Polyglycerol phosphatide is mainly present in the mitochondrial fraction of the tissue‐culture cells.
Isolation of a trimer of α‐tocopherol from mammalian liver
Authors: Draper H. H. , Csallany A. S. , Chiu Mei 
Published: November 2006

AbstractEvidence is presented for the formation in mammalian liver of a trimeric metabolite of α‐tocopherol. This compound has been shown to be identical to a trimer produced by oxidation of α‐tocopherol with alkaline K3Fe(CN)6. In addition, confirmation was obtained for the occurrence in vivo of a dimeric metabolite reported previously. These compounds, together with tocopheryl‐p‐quinone, are postulated to arise from reactions with lipid‐free radicals or peroxides in the course of the antioxidant action of vitamin E.
Phospholipids of the sea anemone: Quantitative distribution; absence of carbon‐phosphorus linkages in glycerol phospholipids; structural elucidation of ceramide aminoethylphosphonate
Authors: Simon Gerald , Rouser George 
Published: November 2006

AbstractThe phospholipid composition of the sea anemone (Anthopleura elegantissima) was determined by quantitative thin‐layer chromatography (TLC). Phosphonic acids were not detected in phosphatidyl choline, phosphatidyl ethanolamine, or phosphatidyl serine following isolation and hydrolysis. The structure of ceramide aminoethylphosphonate, a phosphonolipid, was elucidated by hydrolysis and oxidative degradation followed by characterization of the products by TLC and gas‐liquid chromatography. The long‐chain base was shown to be sphingosine with the 2‐aminoethylphosphonic acid group attached through the primary hydroxyl group at carbon one. Ceramide aminoethylphosphonate is therefore 1‐(O‐phosphonoethylamine)‐N‐acyl sphingosine.
Separation of cholesterol‐desmosterol acetates by thin‐layer and column chromatography on silica gel G‐silver nitrate
Authors: Galli Giovanni , Paoletti Enrica Grossi 
Published: November 2006

AbstractA chromatographic method, using columns packed with Celite‐Silica Gel G impregnated with silver nitrate, has been developed for the separation of cholesterol from desmosterol (24‐dehydrocholesterol).The system employed allows a complete separation of the two sterols as acetates, as determined by gas‐liquid chromatography and thin‐layer chromatography.The recovery of pure cholesterol and desmosterol is quantitative.
DDT absorption and chylomicron transport in rat
Authors: Pocock Dorothy M. E. , Vost Alan 
Published: November 2006

AbstractMale rats were fed 100 nM dichlorodiphenyltrichloroethane‐14C in oil by gastric tube. Recovery of dichlorodiphenyltrichloroethane‐14C in thoracic duct lymph was 60% in 12 hr. Lymph dichlorodiphenyltrichloroethane‐14C (97%) occurred in lipoproteins of d<1.006, designated chylomicrons. Mechanical separation of chylomicron triglyceride core (labeled with triglyceride‐3H) from chylomicron membrane (labeled with phospholipid‐32P) showed that 97% dichlorodiphenyltrichloroethane‐14C was present in triglyceride core. To investigate possible association of plasma clearance of the two core lipids, rats were pulse injected with chylomicrons, doubly labeled with triglyceride‐3H and dichlorodiphenyltrichloroethane‐14C. The decay of dichlorodiphenyltrichloroethane‐14C in sequential serum samples was rapid (T1/2=2 min) and was independent of triglyceride‐3H decay. In tissues removed 14 min after injection of chylomicrons, 30% administered dichlorodiphenyltrichloroethane‐14C was found in liver but only 1% in adipose tissue. In hepatectomized (eviscerated) rats, the decay of serum dichlorodiphenyltrichloroethane‐14C (T1/2=10 min) was also independent of and more rapid than triglyceride‐3H decay. With sucrose density gradients, it was shown that chylomicron dichlorodiphenyltrichloroethane‐14C transferred to higher density serum proteins in vitro and in vivo and to bovine albumin in vitro. Thus, dichlorodiphenyltrichloroethane was transported from intestine largely in the triglyderide phase of chylomicrons; disappearance of chylomicron‐dichlorodiphenyltrichloroethane from the systemic circulation was rapid and partly independent of the presence of the liver and of triglyceride hydrolysis; some dichlorodiphenyltrichloroethane was transported from serum chylomicrons to albumin or other plasma proteins before tissue uptake.
Prostaglandins of rat testis
Authors: Carpenter Mary P. 
Published: November 2006

AbstractThe purpose of the study was to determine whether prostaglandins were present in mammalian testis, a tissue that has a large concentration of polyenoic fatty acids that are potential precursors of prostaglandins. Acid‐soluble lipids of rat testis were extracted, purified, and fractionated by thin layer and column chromatographies.3H‐Prostaglandins were added as internal reference standards to monitor recoveries and facilitate identification. Initial identification of prostaglandin species was done by chromatography. Further identification was done by elution of the prostaglandin zones followed by rechromatographies (both thin layer and column), measurements of UV absorption spectra, and by gas liquid chromatography. The results of these analyses indicate that prostaglandin E1, 11α,15(S)‐dihydroxy‐9‐oxo‐β‐trans‐prostenoic acid; prostaglandin E2, 11α‐15(S)‐dihydroxy‐9‐oxo‐5‐cis‐13‐trans‐prostadienoic acid; and prostaglandin F1, 9α,11α,15(S)‐trihydroxy‐13‐trans‐prostenoic acid occur in rat testicular tissue and that prostaglandin F2α, 9α, 11α, 15(S)‐trihydroxy‐5‐cis‐13‐trans‐prostadienoic acid and prostaglandin E2, 11α,15(S)‐dihydroxy‐9‐oxo‐5‐cis‐13‐trans‐prostadienoic acid may be the primary species of this tissue. Prostaglandin B1, 15(S)‐hydroxy‐9‐oxo‐8(12),13‐trans‐prostadienoic acid and prostaglandin B2, 15(S)‐hydroxy‐9‐oxo‐5‐cis,8(12),13‐trans‐prostatrienoic acid also were detected, and some evidence was obtained for the presence of prostaglandin metabolites.
Bile acid metabolism in mammals: VI. Effect of ethionine upon bile acids of rat bile
Authors: Yousef I. M. , Kakis G. , Fisher M. M. 
Published: November 2006

AbstractSex differences in the effect of ethionine upon rat liver metabolism prompted our investigation into possible sex differences in the effect of ethionine upon bile acid metabolism. The bile ducts of 24 rats, 12 male and 12 female, were cannulated. After 1 hr of bile collection, 6 rats of each sex were given ethionine, 1 mg/g body wt, by feeding tube. The bile acid composition of the bile collected during the subsequent 4 hr was analyzed by combined thin layer and gas chromatography. Ethionine induced a reduction in bile flow (3rd and 4th hr) and in bile acid concentration (4th hr) in female rats. The amino acid had no effect upon bile flow but did increase biliary secretion of bile acids (1st and 2nd hr) in male rats. Cholic acid accounted for the bulk of the reduction in total bile acid secretion in the female studies. The increase in total bile acid secretion in the male studies involved all bile acids. The effects of ethionine upon bile acid secretion were delayed in the female studies, immediate in the male. The changes in bile acid secretion involved only the taurine conjugates in the female studies, both taurine and glycine conjugates in the male. There are substantial sex differences in the effect of ethionine upon bile acid metabolism in the rat.
Mass determination of lipids with automated thermogravimetric analytical procedure
Authors: Leerkamp J. , Siakotos A. N. 
Published: November 2006

AbstractAn automated thermogravimetric system for the microdetermination of lipids is described. A study of the analytical variability experienced with this method revealed that samples can be assayed with considerable accuracy (±3%) down to 100–200 μg, while samples less than this range exhibit variations of ±7–10%. In the absence of other more sensitive methods, even this experimental error is acceptable. In addition, multiple applications of very dilute samples to achieve a lipid mass with an acceptable coefficient of variation is possible. No significant variations were observed with samples assayed on the same day and on different days, indicating a high degree of control of nonoperator errors. A careful application of the method to different lipid classes revealed no significant weighing losses under the experimental conditions of this study, except for cholesterol; however, application of the method to mixtures of lipids containing significant amounts of cholesterol did not reveal abnormal errors.
In vivo and in vitro biosynthesis of free fatty alcohols inEscherichia Coli K‐12
Authors: Naccarato William F. , Gilbertson John R. , Gelman Rose A. 
Published: November 2006

AbstractIn vivo studies have indicated that exogenous free fatty acids may serve as precursors of the free fatty alcohols ofEscherichia coli K‐12. Following disruption of the cells, the enzymatic activity capable of catalyzing the reduction of long chain fatty aldehydes to fatty alcohols was localized in the 100,000 x g supernatant fraction. Nicotinamide adenine dinucleotide phosphate, reduced form, was the required cofactor. The product of the reaction was characterized rigorously as 1‐hexadecanol when hexadecanal was the substrate. Three independent, but complementary, assay methods were developed to assay the aldehyde reductase activity. By employing these methods, an equivalence between nicotinamide adenine dinucleotide phosphate, reduced form, oxidation and 1‐hexadecanol synthesis was established. Two protein fractions catalyzing the reduction of fatty aldehydes to fatty alcohols were detected in the 100,000 x g supernatant fraction following ammonium sulfate fractionation and diethylaminoethyl‐cellulose chromatography. Enzymatic activity (70%) applied to the diethylamino‐ethyl‐cellulose column was eluted at a phosphate concentration of 0.115 M. The remaining 30% was eluted at a concentration of 0.23 M. Following sephadex chromatography, it was observed that the enzyme eluting at 0.115 M phosphate had an apparent mol wt of 250,000 Daltons while that eluting at 0.23 M had an apparent mol wt of 62,000 Daltons. The enzymes were similar with respect to substrate specificity, pH optima, ionic strength optima, and stability with respect to thiol inhibitors, suggesting different sized aggregates of similar subunits.
Embryonic vs tumor lipids: II. Changes in phospholipids of developing chick brain, heart, and liver
Authors: Wood Randall 
Published: November 2006

AbstractBrain, heart, and liver tissues were excised from embryos and chicks 10, 13, 16, 19, 22, 27, and 53 days after incubation was initiated and the lipids extracted. The quantitative distribution of the phospholipids and the fatty acid composition of the individual phosphatides were determined for each time period. Each tissue exhibited a distinct phospholipid composition that differed from the composition of egg. Elevated concentrations of particular phosphoglycerides that characterize certain mature tissues were observed at the earliest time period. As development progressed, some phospholipid classes in all tissues showed dramatic change, while others remained relatively constant. Brain showed the most stable composition, while the phosphatides of liver were the most dynamic. Each phospholipid class exhibited a characteristic fatty acid profile that was unique for each tissue. All of the phospholipid classes showed a change in fatty acid composition as development progressed, and, in some tissue, the change was dramatic. The fatty acid composition of brain phosphoglycerides showed the least change, while liver showed the greatest fluctuation. Docosahexaenoic acid and, in most cases, arachidonic acid decreased in the phosphoglycerides with increased development. The decrease in docosahexaenoic acid correlated well with the decreasing mitotic indices of heart and liver cells as development progressed. Comparison of observed abnormal lipid patterns between mature and neoplastic tissue with embryonic tissue lipid profiles suggest that some of the observed abnormalities of neoplasms probably are due to changes in lipid metabolism associated with rapidly proliferating cells, whereas other abnormalities appear to be associated with neoplasia.
Effect of phospholipase a upon brain cholesterol ester formation
Authors: Ramsey Robert B. , Davison A. N. 
Published: November 2006

AbstractOn addition of snake venom phospholipase A to homogenates of rat brain we have been able to show increased ester formation. Within certain limits, the amount of ester formed was dependent upon the amount of phospholipase added. The fatty acid patterns of free fatty acid released and of cholesteryl ester fatty acid formed during 18 hr incubation were compared. Although fatty acid patterns were different, the data were still consistent with the hypothesis that, in demyelination, a neural phospholipase A may play a role in cholesteryl ester deposition.