bluuebunny/crossref_metadata_2025_split huggingface dataset:
Urinary malondialdehyde as an indicator of lipid peroxidation in the diet and in the tissues
Authors: Draper H. H. , Polensek L. , Hadley M. , McGirr L. G. 
Published: November 2006

AbstractAlthough malondialdehyde (MDA) is extensively metabolized to CO2, small amounts are nevertheless excreted in an acid‐hydrolyzable form in rat urine. In this study, urinary MDA was evaluated as an indicator of lipid peroxidation in the diet and in the tissues. MDA was released from its bound form(s) in urine by acid treatment and determined as the TBA‐MA derivative by HPLC. MDA excretion by the rat was found to be responsive to oral administration of the Na enol salt and to peroxidation of dietary lipids. Urinary MDA also increased in response to the increased lipid peroxidation in vivo produced by vitamin E deficiency and by administration of iron nitrilotriacetate. Chronic feeding of a diet containing cod liver oil led to increases in MDA excretion which were not completely eliminated by fasting or feeding a peroxide‐free diet, indicating that there was increased lipid peroxidation in vivo. MDA excretion was not responsive to Se deficiency or CCl4 administration. DPPD, a biologically active antioxidant, but not BHA, a non‐biologically active antioxidant, prevented the increase in MDA excretion in vitamin E deficient animals. The results indicate that MDA excretion can serve as an indicator of the extent of lipid peroxidation in the diet and, under conditions which preclude a dietary effect, as an index of lipid peroxidation in vivo.
The influence of protein and carbohydrate type on serum and liver lipids and lipoprotein cholesterol in rabbits
Authors: Bauer John E. , Covert Steven J. 
Published: November 2006

AbstractThe non‐lipid portions of semi‐synthetic diets appear to be important determinants of hypercholesterolemia and atherosclerosis in the rabbit. Serum and liver lipid concentrations were determined in rabbits which had been pair‐fed various protein (casein or soy protein isolate) and carbohydrate (sucrose or dextrose) sources as part of low fat, low cholesterol, semi‐synthetic diets. It was verified that caseincontaining diets render rabbits hypercholesterolemic, while soy protein caused a degree of hypocholesterolemia. Additionally, sucrose, when fed in conjunction with casein, appears to augment this hypercholesterolemic effect. The distribution of total cholesterol among lipoprotein subclasses was increased in both the intermediate density lipoprotein (IDL) (1.006–1.019 g/ml) and low density lipoprotein (LDL) (1.019–1.063 g/ml) fractions and decreased in the high density lipoprotein (HDL) (1.063–1.21 g/ml) fraction when casein is fed. Soy protein feeding caused relatively more cholesterol to appear only in the IDL fraction when compared with commercial chow fed rabbits. Reasons for these differences may involve the saturation or suppression of endogenous lipoprotein hepatic receptors.
Lung surfactant phospholipids in different animal species
Authors: Shelley Sue A. , Paciga June E. , Balis John U. 
Published: November 2006

AbstractA comparative study of adult mammalian lung surfactants was undertaken to determine which animal species might serve as appropriate models for surfactant alterations in human lung diseases. Phosphatidylcholine (PC) comprised 80–87% of the phospholipid and contained more than 65% palmitic acid in all species studied. Phosphatidylglycerol (PG) was found to vary significantly in fatty acid composition among the species. Rabbit, dog and rat surfactant PG contained 50–60% palmitic acid, while human and cat surfactant contained much lower levels of saturated fatty acids. Both the PC and PG of all species contained 2 positional isomers of fatty acids with 16 carbons and one double bond, but the relative amounts of the unusual isomer, 16∶1Δ7, and palmitoleic, acid, 16∶1Δ9, varied among the different animal species. Only cat and dog surfactant phospholipids contained 18∶1Δ5. Cat surfactant phospholipids also differed by the absence of 20∶4 and the presence of small amounts of several 20‐ and 22‐carbon fatty acids. These results explain some discrepancies found in the literature concerning surfactant composition and delineate limiting factors in extrapolating results from animal studies for the evaluation of maturation and pathological alterations in human surfactant.
Peroxidation of free and esterified fatty acids by horseradish peroxidase
Authors: Garner Charles W. 
Published: November 2006

AbstractLinoleic and arachidonic acids and unsaturated esterified fatty acids of soybean lecithin liposomes were oxidized by horseradish peroxidase in the presence of hydrogen peroxide. The major products formed in the presence of oxygen were fatty acid hydroperoxides. In the absence of oxygen, other unidentified products were formed. Diene conjugation was about 5 times faster in oxygen than in nitrogen. Malondialdehyde was formed only in the presence of oxygen. Superoxide, singlet oxygen and hydroxyl radical may have been involved in the free fatty acid oxidation system but not in the liposome system. Replacement of hydrogen peroxide with the hydrogen peroxide (and superoxide) generators xanthine oxidase or galactose oxidase caused a more efficient oxidation in the presence of peroxidase than in its absence, suggesting that the in vivo toxicity of hydrogen peroxide and superoxide may be greatly increased in the presence of peroxidase.
Intestinal metabolism of plasma free fatty acids in streptozotocin diabetic rats
Authors: Renner F. , Schernthaner G. , Gangl A. 
Published: November 2006

AbstractModerate insulin deficiency was reported to be accompanied by an increased production of intestinal very low density lipoprotein (VLDL) triglyceride in the rat. Because plasma free fatty acids (FFA) are incorporated into triglyceride by intestinal mucosa of rats and humans and plasma FFA are increased in insulin‐deficient diabetes mellitus, we investigated several aspects of the intestinal metabolism of plasma FFA in diabetic rats. All experiments were performed on the third day following the i.v. injection of streptozotocin (45 mg/kg body weight) or buffer alone. A (14C)palmitic acid‐rat serum complex was rapidly injected intravenously and its initial uptake by small bowel mucosa, the intracellular incorporation into lipids and water soluble metabolites and the specific radioactivity of triglycerides of mucosal homogenates was determined. No significant differences could be found between diabetic and control rats at 2 and 5 min after14C‐palmitate i.v., suggesting that neither the influx of plasma free fatty acids into intestinal mucosal cells nor their initial intracellular metabolic pathways are significantly altered in moderately diabetic rats. A pronounced decrease in intestinal mucosal triglyceride at 10 min after14C‐palmitate i.v. might be interpreted as indirect evidence for an enhanced triglyceride efflux from intestinal mucosa into mesenteric lymph in diabetic rats.
Analysis of sterol esters by capillary gas chromatography‐electron impact and chemical lonization‐mass spectrometry
Authors: Lusby William R. , Thompson Malcolm J. , Kochansky Jan 
Published: November 2006

AbstractSynthetic mixtures of C40 to C47 sterol esters in groups of 7 esters were effectively separated and analyzed by capillary gas chromatography‐mass spectrometry. Ammonia chemical ionization of all 20 sterol esters analyzed at a source block temperature of 120 C yielded (M+NH4)+ and (M+H‐RCO2H)+ ions of high abundance or as base peak, thereby indirectly indicating the molecular weights of the ester and the sterol and acid moieties. Ammonia CI spectra of all esters containing a Δ5‐sterol moiety exhibited in addition to the above 2 ions an M+NH4‐RCO2 H fragment. At a source block temperature of 150 C, M+H‐RCO2 H fragment was the base peak for all esters, and there was little or no indication of an (M+NH4)+ adduct ion. Protonated molecules were not observed for any esters analyzed by methane or isobutane CI. Molecular ions of 3–14% intensity were obtained for only 3 of the esters analyzed by electron impact; they contained a Δ7‐bond in the sterol nucleus, and the acid moiety was either saturated normal or branched chain or contained a single double bond. The base peak was a function of both the acid and sterol moieties of the sterol ester. The esters containing both saturated straight chain acid and saturated sterol moieties exhibited a base peak at m/z 215. The Δ5‐sterol esters with saturated branched or straight chain acid moieties exhibited base peaks at M‐RCO2 H. Other ions also were of diagnostic value.
Properties of diacylglycerol acyltransferase from spinach leaves
Authors: Martin B. A. , Wilson R. F. 
Published: November 2006

AbstractDiacylglycerol‐acyltransferase (EC 2.3.1.20) was partially purified and characterized from spinach leaves. The enzyme had a pH optimum of 8.0 and activity was stimulated 2‐fold by the addition of 20 mM Mn2+ or Mg2+. Diolein and dipalmitin were examined assn‐1,2‐diacylglycerol substrates. Only diolein gave detectable triacylglycerol synthesis. In addition, the saturation kinetics of the enzyme with 16∶0‐CoA, 18∶0‐CoA and 18∶1‐CoA were examined. The highest apparent, Km was observed with 18∶1‐CoA, the lowest with 16∶0‐CoA. Endogenous spinach leaf glycerolipids were extracted and analyzed. The leaves contained 70 nmol triacylglycerol (g fresh weight)−.
Effect of environmental temperature changes on rat liver fatty acid desaturases
Authors: Gonzalez Susana , Nervi Anibal M. , Peluffo Raúl O. , Brenner Rodolfo R. 
Published: November 2006

AbstractFemale rats warm‐adapted at 30–32 C for 20–25 days and then shifted to 13–15 C for 12, 24, 48, 72 and 120 hr showed that Δ9 desaturase and fatty acid synthetase activity decay after 24 hr of cold exposure, while Δ6 and Δ5 desaturases were increased after this period of time. These results were confirmed by an increase of arachidonic acid of heart and liver microsomes phosphatidylcholine and a decrease of oleic acid. Neither NADH‐cyt b5 reductase nor NADH‐cyt c reductase activity of liver microsomes were significantly affected. Male rats warm‐adapted under the same conditions and then shifted to 13–15 C for 120 hr did not show significant changes in fatty acid synthetase, Δ9 and Δ6 desaturases and enzymes of the microsomal electron transport chain. Therefore, the desaturase response to environmental temperature changes could be plausibly linked to female hormones.
Cholesterol esterifying capacity of various organs in cholesterol‐fed guinea pigs
Authors: Heller F. R. 
Published: November 2006

AbstractIn guinea pigs fed a diet enriched with 1% cholesterol, the liver, adrenals, spleen, and small intestine accumulated cholesterol much more than the lungs and kidneys. The cholesterol content of the aorta, stomach and colon was not increased by the diet. Cholesteryl ester was the predominant form of cholesterol deposited in the organs richest in this sterol and the total cholesterol content of a tissue tended to increase with the proportion of cholesteryl ester. Cholesterol esterifying activity (ACAT) was found in most tissues and paralleled the cholesteryl ester content of these tissues, being highest in the adrenals, liver, spleen and the proximal part of the small intestine. ACAT activity was enhanced by the cholesterol diet and its elevation was fairly well correlated with the increase in the cholesterol content of the organs. However, the liver and adrenals tended to accumulate more cholesterol than anticipated from their cholesteryl ester content and their ACAT activity. Cholesterol esterification may play a major role in the ability of organs to accumulate cholesterol.
Dietary squalene increases tissue sterols and fecal bile acids in the rat
Authors: Tilvis Reijo S. , Miettinen Tatu A. 
Published: November 2006

AbstractFeeding 1% squalene increased markedly the concentrations of squalene and methyl sterols in each serum lipoprotein class, intestinal mucosa, liver and also in adipose tissue. It also increased cholesterol concentration of the liver and serum VLDL, and esterified cholesterol in serum LDL as well as fecal bile acids. The results suggest that absorbed dietary squalene contributes to some extent to the squalene content of adipose tissue, effectively increases the overall cholesterol synthesis and enhances cholesterol elimination preferentially as fecal bile acids.
Peroxidative formation of C3‐hydrocarbons from an ω‐4 polyunsaturated fatty acid(16∶3ω4) in the algaBumilleriopsis
Authors: Sandmann Gerhard , Böger Peter 
Published: November 2006

AbstractUnder peroxidative conditions (i.e., illumination in the presence of Cu2+ or ap‐nitro diphenylether herbicide), the xanthophycean microalga,Bumilleriopsis filiformis, evolves C2 and C5 hydrocarbons besides substantial amounts of propane and propene. Fatty acids were separated as methyl esters by argentation and reversed‐phase thin layer chromatography and the fractions subsequently peroxidized by illuminated and copper‐supplementedAnacystis thylakoids. These membranes do not contain polyunsaturated fatty acids and are, therefore, unable to evolve volatile hydrocarbons by itself. The C2 and C5 hydrocarbons formed by the fractions added match with their content of ω‐3 and ω‐6 fattyacid species having 2–4 double bonds. The fractions yielding C3 hydrocarbons contain a fatty acid hitherto unknown forBumilleriopsis, which was isolated and identified as 16∶3ω4.
Unsaturated fatty acids in the postnatally developing rat lung
Authors: Kehrer James P. , Autor Anne P. 
Published: November 2006

AbstractFatty acid desaturase activity specific for the C‐9 position is present in lung microsomes prepared from rats of all ages. This activity is significantly lower in neonatal rat lung compared with adult lung. A rapid increase in C‐9 fatty acid desaturase activity seen at the approximate time of weaning may be related to a decrease in the polyunsaturated fatty acid (PUFA) content of the diet as the rat begins to consume laboratory chow instead of mother's milk. The 900×g supernatant fraction of rat lung parenchymal cell homogenates is capable of incorporating linoleate, linolenate, and arachidonate into both triacylglycerols and phospholipids. Lung tissue from rats less than 20 days old incorporates these PUFA into phospholipids at a greater rate than lung, tissue from adult rats. The incorporation of these PUFA into phospholipids in neonatal lung tissue occured at a greater rate than their incorporation into triacylglycerols. In contrast, lung tissue from adult rats incorporated PUFA into triacylglycerols at a greater rate than into phospholipids. These data show that PUFA, known to be elevated in neonatal rat lungs, are used primarily for phospholipid biosynthesis in neonatal lung tissue whereas in adult lung tissue they are preferentially esterified to glycerol.
Fatty acid composition of polar lipids in goats' milk
Authors: Cerbulis J. , Parks O. W. , Farrell H. M. 
Published: November 2006

AbstractSilicic acid column chromatography was used to separate the polar lipids of goats' milk into glycolipid, phosphatidylethanolamine, phosphatidylserine plus phosphatidylinositol, phosphatidylcholine, and sphingomyelin fractions. Each fraction was purified by column chromatography and its fatty acid profile determined by gas liquid chromatography and mass spectrometry. The glycerophospholipids each contained 18∶1 as the predominant fatty acid (∼45%). The sphingolipids contained a high percentage of long‐chain saturated fatty acids (C22 to C24>45%); the glycolipid fraction also contained ca. 2% 2‐hydroxy fatty acids. The data represent a comprehensive cross‐sectional study of the major polar lipids found in goats' milks.
Chemical lonization mass spectrometry of wax esters
Authors: Plattner R. D. , Spencer G. F. 
Published: November 2006

AbstractChemical ionization (CI) mass spectra of long‐chain saturated, monenoic and dienoic wax ester analogues, using isobutane and methane as reagent gases, are reported and compared. Because less fragmentation occurs, CI spectra are simpler than the electron impact spectra. The quasi molecular ion (M+1) is the base peak in the spectra. Saturated, monenoic and dienoic wax ester mixtures have been analyzed by this technique.
Complexities in lipid quantitation using thin layer chromatography for separation and flame lonization for detection
Authors: Crane R. Thomas , Goheen Steven C. , Larkin Edward C. , Rao G. Ananda 
Published: November 2006

AbstractThe use of thin layer chromatography (TLC) for separation (using silica gel coated quartz rods) and subsequent flame ionization for detection (FID) was examined to determine whether this method could be used for the quantitation of lipids. However, response factors (RF) for various lipids were different and depended upon several variables including the amount of material analyzed. For example, RF were 3‐fold greater when 10 μg of tripalmitin was analyzed as compared to 1 μg of the same material. The amount of lipid detected by FID was also dependent upon the rate at which it passed through the flame. During analysis of methylpentadecanoate, detector response increased with scan speed, while at all speeds it was completely removed from the rod. On the other hand, depending upon the amount of cholesterol or phospholipid analyzed, the response either increased, remained unchanged or decreased with scan speed. During a fast scan, detector response was reduced because some material remained on the rod. Thus, the detector response is influenced by sample volatility. In conclusion, there appears to be a complex relationship between detector response and the amount of heat available per microgram of sample. Since we could not find a direct correlation between detector response and sample quantity, it would be difficult to use TLC‐FID as a tool for quantitating the components of a lipid mixture.
Electron spin resonance spectra of the chromanoxyl radicals derived from tocopherols (vitamin E) and their related compounds
Authors: Matsuo Mitsuyoshi , Matsumoto Shigenobu 
Published: November 2006

AbstractThe well resolved electron spin resonance (ESR) of the tocopheroxyl and chromanoxyl radicals derived from α‐, β‐, γ‐ and δ‐tocopherols (vitamin E), 5,7‐dimethyltocol, tocol and their model compounds in degassed toluene by treatment with 2,2‐diphenyl‐1‐picrylhydrazyl were recorded. Their hyperfine coupling constants were determined and assigned using spectrum simulation. Their g‐factors were also measured. On the basis of these parameters, the α‐tocopheroxyl radical is similar to the 2,2,5,7,8‐pentamethylchroman‐6‐oxyl, 5,7‐dimethyltocoxyl and 2,2,5,7‐tetramethylchroman‐6‐oxyl radicals. This suggests that the presence of methyl groups at C‐5 and C‐7 in tocopherols and chroman‐6‐ols is of great importance to their antioxidant action. The ESR parameters obtained here are very useful for the identification and quantification of a variety of tocopheroxyl radicals.
Analysis of conjugated bile acids by high performance liquid chromatography and mass spectrometry
Authors: Mingrone G. , Greco A. V. , Boniforti L. , Passi S. 
Published: November 2006

AbstractBecause of the known advantages of coupling high performance liquid chromatography with mass spectrometry (HPLC‐MS) in biological fluids, studies on the reversed‐phase HPLC‐MS system for direct analysis of conjugated bile acids in human bile samples are described. Ten samples of gallbladder bile of apparently healthy subjects were examined. The amounts of each tauro‐ and glycoconjugated bile acid as trifluoracetate were determined by mass fragmentography. Quantitation of at least 1 ng of each bile acid was possible.
Alteration in membrane permeability by diacylglycerol and phosphatidylcholine containing arachidonic acid
Authors: Yorio Thomas , Torres Susana , Tarapoom Nimnan 
Published: November 2006

AbstractThe phospholipid metabolites, stearoylarachidonylglycerol and diarachidonylglycerol, stimulate transepithelial sodium transport in frog skin epithelium. The increase in Na transport is due to an increase in the unidirectional influx of sodium, is amiloride sensitive and is prevented with pretreatment with indomethacin, mefanamic acid and phospholipase inhibitor, mepacrine. The data suggest a possible role of phospholipid metabolism and prostaglandin biosynthesis in the regulation of transepithelial ion transport.
Sterol composition of two freshwater molluscs of genusDiplodom
Authors: Pollero Ricardo J. , Gros Eduardo G. , Brenner Rodolfo R. 
Published: November 2006

AbstractThe sterol composition of two taxonomically related freshwater species,Diplodom patagonicus andDiplodom variabilis, respectively, from Lake Nahuel Huapi and the Río de la Plata river were studied by gas liquid chromatography and mass spectrometry. Cholesterol was the main sterol in both species and it was followed by 24‐methylcholesta‐5, 22‐dien‐3β‐ol, 24‐methylcholest‐5‐en‐3β‐ol, 24‐ethylcholesta‐5,22‐dien‐3β‐ol and 24‐ethylcholest‐5‐en‐3β‐ol. The river species collected within the proximity of marine influence showed less cholesterol and more 24‐methylcholesta‐5,22‐dienol, 24‐methylcholest‐5‐enol and 24‐ethylcholesta‐5,22‐dienol than the lake species.
Lipid composition and prostaglandin synthesis in mouse lung microsomes: Alterations following the ingestion of menhaden oil
Authors: Lokesh B. R. , Kinsella J. E. 
Published: November 2006

AbstractThree groups of male mice were fed a normal diet or a semisynthetic diet containing either 10% hydrogenated coconut oil (CO group) or 10% menhaden oil (MO group) for two wk. The synthetic diet altered the fatty acid composition of lung microsomal lipids. Mice ingesting menhaden oil contained greater amounts of eicosapentaenoic acid (20∶5 n−3), docosapentaenoic acid (22∶5 n−3) and docosahexaenoic acids (22∶6 n−3) and decreased amounts of n−6 fatty acids such as arachidonic and adrenic. Synthesis of prostaglandin E2 and prostaglandin F2α from exogenous arachidonic acid was significantly depressed in n−3 fatty acid‐enriched lung microsomes. These studies indicated that dietary fish oil not only alters the fatty acid composition of lung microsomes but also lowers the capacity of lungs to synthesize prostaglandins from arachidonic acid.
Fluorescent pigments by covalent binding of lipid peroxidation by‐products to protein and amino acids
Authors: Fukuzawa Kenji , Kishikawa Katsuya , Tokumura Akira , Tsukatani Hiroaki , Shibuya Masayuki 
Published: November 2006

AbstractThe fluorescent products formed on reaction of 12‐oxo‐cis‐9‐octadecenoic acid (12‐keto‐oleic acid) with about 20 different amino acids, polylysine and bovine serum albumin (BSA) were studied. Besides glycine, only the basic amino acids histidine, lysine and arginine gave products with strong fluorescence. N‐Acetylation of amino acids greatly reduced the fluorescence of their reaction products. The formation of fluorescent products was inhibited strongly by SH‐amino acids such as N‐acetyl‐cysteine and glutathione. Polyacrylamide gel electrophoresis showed that BSA treated with 12‐keto‐oleic acid was more acidic than untreated or ricinoleic acid‐treated BSA, indicating that basic amino acid residues in BSA were modified by reaction with the keto fatty acid. None of the structural analogs of 12‐keto‐oleic acid tested–12‐oxo‐trans‐10‐octadecenoic acid, 12‐oxo‐octadecanoic acid, 12‐hydroxy‐cis‐9‐octadecenoic acid (ricinoleic acid),cis‐9‐octadecenoic acid (oleic acid) and linoleic acid—reacted with glycine to give a fluorescent product. The fluorescent products formed on reaction of 12‐keto‐oleic acid methyl ester with benzyl amine and glycine methyl ester were shown to be 8‐(N‐substituted‐4,5‐dihydro‐4‐oxo‐5‐hexyl‐5‐hydroxy‐2‐pyrrolyl) octanoic acid methyl esters. The fluorescence properties of these compounds were attributed to the chromophobic system NC=CC=O which contains 6π electrons. This investigation contributes to insight of the mechanism of formation of fluorescent pigments, probably by a similar reaction of other compounds of the β,γ‐unsaturated carbonyl type.