bluuebunny/crossref_metadata_2025_split huggingface dataset:
The purification and specificity of a lipase fromVernonia anthelmintica seed
Authors: Olney C. E. , Jensen R. G. , Sampugna J. , Quinn J. G. 
Published: November 2006

AbstractAcetone powders prepared fromVernonia anthelmintica seed catalyzed the release of 6.4 to 9.6 μ‐moles of free fatty acids per milligram of protein when blended with olive oil and phosphate buffer and shaken for 20 min at 43 C. A 20 fold purification was achieved by differential centrifugation of an ammonium hydroxide extract of the acetone powder. Results from Sephadex G‐200 chromatography and polyacrylamide gel electrophoresis suggested that the lipase activity was associated with a molecule of molecular weight greater than 200,000. Free fatty acids, 1,2‐ and 1,3‐diglycerides, monoglycerides and glycerol were found in the digestion products. With most substrates the 1,2‐to 1,3‐diglyceride ratio was approximately 2∶1 and monoglycerides tended to accumulate. Analysis of the digestion products from synthetic triglycerides of known structure indicated that both primary and secondary ester positions of the triglyceride molecule were hydrolyzed and that considerable isomerization of 1,2‐diglyceride to 1,3‐diglyceride occurred. The monoglyceride was consistently lower than the 1,2‐diglyceride and in the majority of cases also lower than the 1,3‐diglyceride in the fatty acid originally present in the 2 position of the triglyceride. No fatty acid preference was observed.
The effect of antioxidant deficiency on tissue lipid composition in the rat. III. Testes
Authors: Witting L. A. , Likhite V. N. , Horwitt M. K. 
Published: November 2006

AbstractProduction of testicular degeneration in the antioxidant‐deficient rat resembles encephalomalacia in the chick in its dependence on essential (ω6) fatty acids and is distinct from the generalized response to all polyunsaturated fatty acids seen in nutritional muscular dystrophy in the rat. The nonessential (ω3) polyunsaturated fatty acids, however, lower the essential fatty acid content of the testicular lipids only slightly, are not themselves incorporated into this tissue to any appreciable degree and thus do not show the inhibitory effect on production of the antioxidant‐deficiency sign noted in the studies on encephalomalacia. A direct relationship between the essential fatty acid content of the testes and the rate of testicular degeneration was found, but no effects of biologically available selenium and sulfur amino acids were evident. As the liver and muscle, onset of antioxidant‐deficiency is characterized by a decrease in the most highly unsaturated fatty acid in the tissue (22∶5–ω6 in this case) and a net increase in arachidonate.
The effect of antioxidant deficiency on tissue lipid composition in the rat. IV. Peroxidation and interconversion of polyunsaturated fatty acids in muscle phospholipids
Authors: Witting L. A. 
Published: November 2006

AbstractIt has been suggested that the net changes which take place in the composition of the muscle phospholipid fatty acids of the antioxidant‐deficient rat represent the balance of two opposing processes. To compensate for (A) the preferential peroxidative destruction of the most highly polyunsaturated fatty acids in the tissue there occurs (B) an increase in the conversion of available precursors to the higher polyunsaturated fatty acids. Analysis of the data in terms of peroxidation kinetics indicated that the onset of creatinuria in one group after 3 weeks and in a second group after 7 weeks on an antioxidant‐deficient diet occurred in both cases concomitant with the peroxidative “disappearance” of approximately 125 μg of phospholipid polyunsaturated fatty acid per gram wet weight of tissue or 2% of the total muscle phospholipid fatty acids.
Mechanism of suckling‐rat hypercholesteremia. II. Cholesterol biosynthesis and cholic acid turnover studies
Authors: Harris R. A. , Rivera E. R. , Villemez C. L. , Quackenbush F. W. 
Published: November 2006

AbstractCholesterol biosynthesis from acetate‐2‐14C by the livers of suckling rats, which is known to be relatively slow, was increased 2–3‐fold within 24 hours after severing the bile duct. Cholesterol synthesis by sham‐operated litter mates showed no change under similar treatment. Mevalonate biosynthesis from acetate‐2‐14C in vitro by recombined liver microsomal supernatant (105,000×g) fractions from suckling rats also was only 10% of that of comparable recombined fractions from normal controls (young adult rats which were consuming colony diet). Activity was not improved by combining either the microsomal or supernatant fraction from suckling rat livers with the complementary fraction from normal adult livers. On the other hand, activity was restored to 100% when microsomes from livers of duct‐served suckling rats were combined with the supernatant fraction from normal controls. Likewise, recombined liver fractions prepared from adult rats fed synthetic diets exhibited low activity for mevalonate biosynthesis. Activity was restored by bile duct cannulation, but inhibited when cholic acid was infused into the cannulated animal. Therefore, surgical procedures which interrupt the enterohepatic recirculation of bile components lead to a restoration of cholesterol biosynthesis and, at least in the adult animal where cannulation studies are practicable, this effect can be reversed readily by bile acid infusion.A slow rate of fecal excretion of14C‐cholic acid was observed in suckling rats and rats fed synthetic diets, apparently reflecting an efficient enterohepatic recirculation of bile salts. The data suggest that under these dietary conditions bile salt retention either directly or indirectly influences hepatic synthesis of cholesterol.
Metabolism of unsaturated fatty acids in the intestine
Authors: Bottino Nestor R. 
Published: November 2006

AbstractRats fed a fat‐free diet from weaning were contined on that diet alone or supplemented with methyl linoleate, methyl linoleate plus a mixture of antibiotics, or methyl arachidonate.Dietary linoleate and arachidonate reduced the concentration of octadecenoic acid and increased that of stearic acid in the mucosa and luminal lipids. This effect was prevented in the mucosa but not in the intestinal contents by antibiotic supplementation of the linoleate diet.Evidence for the conversion of linoleic into eicosatetraenoic acid was found in both mucosa and luminal lipids. The conversion was impaired by the addition of antibiotics to the diet.Linoleate feeding combined with antibiotic addition provided evidence for the intestinal hydrogenation of dietary linoleic into either octadecenoic or stearic acids by separate routes, the latter being impaired by antibiotic ingestion.The ingestion of methyl linoleate or arachidonate modified only slightly the fecal fatty acid pattern of rats previously on a fat‐free diet.
Dietary fat effect on incorporation and release of lipids and cholesterol by rat intestinal slices
Authors: Pawar Sitaram S. , Tidwell Herbert C. 
Published: November 2006

AbstractThe effect of saturated and unsaturated fats on in vitro formation and release of lipids and cholesterol from14C acetate by rat intestinal tissue was investigated. The rats were fed a basal diet enriched with either 25% corn oil or lard and then sacrificed after a 10‐ or 25‐day feeding period. It was observed that a similar14C lipid content but a greater14C cholesterol content was found in the intestinal tissue of rats fed corn oil than in rats fed lard for 10 days. After a longer period of feeding of 25 days, the intestinal tissue14C cholesterol level was decreased in the corn oil fed rats without any significant effect on other lipids. These data suggest that corn oil in some way influences cholesterol biosynthesis depending upon its degree of unsaturation and the period of time for which it is fed. The decrease at the later time might involve some mechanism which aids in getting rid of accumulated tissue cholesterol. Less14C lipid and14C cholesterol were released by the intestinal tissue of rats fed the unsaturated fat as compared with those fed the saturated fat, suggesting a possible role in vivo in reducing blood lipids and blood cholesterol levels.
In vitro incorporation of acetate‐1‐14C into the phospholipids of rabbit and human endometria
Authors: Morin Robert J. , Carrion Maria 
Published: November 2006

AbstractEndometria from nonpregnant and 6‐day pregnant rabbits and from humans in the proliferative and secretory phases were incubated with 1‐14C‐acetate.14CO2 was collected, and subsequently the amounts, specific radioactivities, and in some cases the fatty acid compositions of the isolated phospholipids were determined. Phosphatidyl choline was the phospholipid present in highest amount in endometria from both nonpregnant and pregnant rabbits, and in human endometria; this phospholipid also showed the highest degree of incorporation of14C‐acetate. Pregnancy in the rabbit seemed to decrease the incorporation of14C‐acetate into most of the endometrial phospholipid classes. In humans, the incorporation of acetate into phosphatidyl choline and phosphatidyl ethanolamine was lower in the secretory than the proliferative endometria.Of the fatty acids, linoleic acid in phosphatidyl choline and phosphatidyl ethanolamine of the rabbit endometria showed a significant relative increase during pregnancy and palmitoleic acid showed a decrease.
The in vivo incorporation of labeled linoleic acid, α‐linolenic acid and arachidonic acid into rat liver lipids
Authors: De Tomas Maria Elena , Mercuri Osvaldo 
Published: November 2006

AbstractThe incorporation of 1‐14C‐linoleic acid, 1‐14C‐α‐linolenic acid and 1‐14C‐arachidonic acid into rat liver lipids was measured and the per cent distribution of radioactivity into the different lipid fractions determined. Normal rats were injected into the portal vein with the labeled solutions during a one minute period. Livers were quickly frozen, pulverized, and the lipids extracted and fractioned by thin layer chromatography. No significant differences were observed in the amounts of labeled fatty acids incorporated per gram of rat liver. While 1‐14C‐linoleic acid and 1‐14C‐α‐linolenic acid were found in appreciable amounts in the 1,2 diacylglycerol fraction, about one fifth as much 1‐14C‐arachidonic acid was esterified in this fraction. 1‐14C‐arachidonic acid was the leading acid esterified in the phospholipid fractions.
Response of rat adrenal cholesteryl esters to cold stress
Authors: Walker Brian L. , Carney James A. 
Published: November 2006

AbstractMale rats were maintained on diets containing corn oil or hydrogenated coconut oil. The compositions of the adrenal cholesteryl esters were determined in control animals and in those subjected to cold stress (4 C for 30 min). Total sterol ester content was lower in the stressed rats. In those receiving corn oil there were selective decreases in 16∶1, 18∶2 and 20∶4(n−6) esters but not in 22∶4(n−6). In the coconut oil fed, essential fatty acid (EFA) deficient animals, the decreases in 20∶4(n−6) and 22∶4(n−6) were quite selective, but the concentrations of the cholesteryl esters of 20∶3(n−9) and 22∶3(n−9) were also selectively reduced in the stressed animals. Olive oil and corn oilethyl erucate were employed as dietary fats in a second experiment. Plasma corticosterone was lower in animal fed ethyl erucate and subjected to cold stress. Cholesteryl erucate was the major adrenal ester in animals receiving dietary erucate but it was not well utilized in animals subjected to stress. The cholesteryl esters of linoleate and arachidonate were preferentially utilized in both of these dietary groups. Cholesteryl arachidonate was selectively utilized in all four dietary groups studied and may constitute the preferred substrate for rat adrenal cholesteryl ester hydrolase.
A comparison of triglyceride, monoglyceride, and phospholipid substrates for post‐heparin lipolytic activities from normal and hypertriglyceridemic subjects
Authors: Vogel William C. , Brunzell John D. , Bierman Edwin L. 
Published: November 2006

AbstractEvidence for heterogeneity of postheparin lipolytic activities in plasma was explored. After low or high doses of heparin, activities were measured in assays with phospholipid or monoglyceride substrate and with triglyceride substrate in assays using either calcium or albumin as the fatty acid acceptor. An excellent correlation between all assays was obtained in normals after both low and high doses of heparin over a wide range of individual response. In selected subjects with hypertriglyceridemia known to be deficient in response to heparin, all responses measured with phospholipid or triglyceride were below the lower limit of normal response. Some responses with monoglyceride substrate were within the normal range, pathophysiological evidence of a separate monoglyceridase. There was no evidence in either group of separate triglyceride lipase and phospholipase activities. The closest correlation between assays in normals was between triglyceride substrate with calcium as the fatty acid acceptor and the assay with monoglyceride. No differential effect upon lipolytic activities was found (1) after preincubation of the plasma, (2) with inhibitors in the assay, or (3) with preincubation of plasma and inhibitors prior to the assay.
Isolation and identification of cholesterol α‐oxide and other minor sterols in human serum
Authors: Gray M. F. , Lawrie T. D. V. , Brooks C. J. W. 
Published: November 2006

AbstractThe isolation and identification of cholesterol α‐oxide, coprostanol, β‐sitosterol, cholest‐4‐en‐3‐one and cholesta‐4, 6‐dien‐3‐one from human serum are reported. Compounds were isolated by thin layer chromatography and were identified by gas liquid chromatography and gas chromatography‐mass spectrometry (GC‐MS). Data for standard sterols are also reported. The possible origins of these minor components and the significance of their presence are discussed.
Metabolism of phospholipid in mammary gland: I. The supply of phospholipid for milk synthesis in the rat and goat
Authors: Easter D. J. , Patton S. , McCarthy R. D. 
Published: November 2006

AbstractData presented in this study demonstrate that under normal physiological conditions milk phospholipids in the rat and the goat originate predominantly, if not totally, by de novo synthesis within the mammary gland. Evidence to support this has been obtained for the goat by measurement of P32‐phosphate incorporation into milk phospholipids, and in the rat by measurement of P32‐phosphate incorporation and by feeding radioactive phospholipid to measure the incorporation of serum phospholipids into milk. The latter experiment showed that the fatty acid portion of the dietary phospholipid can readily be utilized by the mammary gland for triglyceride synthesis, but that the contribution of the serum phospholipid “backbone” to milk phospholipid is minimal.
On the origin of oil droplets in maturing castor bean seeds,Ricinus communis
Authors: Harwood J. L. , Sodja Ann , Stumpf P. K. , Spurr A. R. 
Published: November 2006

AbstractFat droplets isolated from maturing castor bean seeds contain high concentrations of fatty acid synthetase and triglyceride synthesizing enzymes. These activities are not due to contamination by other organelles and account for at least 80% of the total lipid synthesis. Electron microscopy of the isolated oil droplets and the seed tissue in vivo revealed particulate containing vacuole‐like inclusions which, it is suggested, are the site of lipid synthesis and which form the original locus of the droplet.
Early steps on the in vivo incorporation of 1‐14C‐linoleic acid into liver lipids from normal and essential fatty acid deficient rats
Authors: Mercuri Osvaldo , De Tomas Maria Elena 
Published: November 2006

AbstractEssential fatty acid (EFA) deficient rats were injected intraportally with a solution of 1‐14C‐linoleic acid during a 1 min period. Livers were quickly frozen, pulverized, and the lipids extracted and fractioned by thin layer chromatography. The incorporation of 1‐14C‐linoleic acid into liver lipids was measured. The results were compared with those previously obtained from normal rats. No significant differences were observed in the total radioactivity recovered from lipid extracts. While the distribution of radioactivity into the 1–2 diacylglycerol fraction remained unchanged in both groups of rats, in the EFA deficient rats the 1‐14C‐linoleic acid incorporation was actually directed to the phospholipid fractions instead of to the triacylglycerol fractions as was observed in the normal rats.
Reactions of biological antioxidants: II. Fe(III)‐catalyzed reactions of methyl linoleate hydroperoxides with derivatives of coenzymes Q and vitamin E
Authors: Gruger E. H. , Tappel A. L. 
Published: November 2006

AbstractLipid free‐radical oxidations of ubiquinol‐6, ubichromenol‐6, ubichromenol‐10, and α‐tocopherol hydroquinone were kinetically examined in the presence of Fe(III)‐catalyzed dissociations of preformed methyl linoleate hydroperoxides. The rates of oxidation of the chromenols increased more than those of the hydroquinones as reaction acidity was increased. Differences in thermal effects upon rates were influenced by the levels of water in the reactions. The hydroquinones exhibited faster rates relative to α‐tocopherol than the ubichromenols, while the rates for the latter varied markedly depending on the nature of the solvent.
Determination of specific activity of isotopic materials by thin layer chromatography
Authors: Wortmann Wil , Kasparow Maria , Touchstone Joseph C. 
Published: November 2006

AbstractA modified method for determination of specific activity by thin layer chromatography (TLC) is described. Based on in situ spectrodensitometry after separation by TLC, the method is rapid and requires amounts of reference material in the microgram range.
Phospholipid reactivation of plasmalogen metabolism
Authors: Ellingson John S. , Lands William E. M. 
Published: November 2006

AbstractThis report is concerned mainly with the properties of an enzyme from rat liver microsomes which hydrolyzes the alkenyl ether bond of 1‐(1′‐alk‐1′‐enyl)‐glycero‐3‐phosphoryl‐choline (alkenyl‐GPC hydrolase).Destruction of the normal environment of the microsomes by treatment with phospholipases A or C caused inactivation of the alkenyl‐GPC hydrolase, which was then partially reactivated by the addition of exogenous phospholipids. Both sphingomyelin and diacyl‐GPC were efficient in restoring activity; diacyl‐GPE was less effective; and monoacyl‐GPC and monoacyl‐GPE were ineffective. The presence of two long hydrocarbon chains in the lipid activator is apparently required for reactivation, suggesting that interaction of hydrophobic areas of the enzyme with the phospholipid is necessary for maximal activity. High concentrations of sucrose mimicked the effect of phospholipids, and because the sucrose and diacyl‐GPC did not show an additive effect, they may reactivate the enzyme in a similar manner.Disrupting the enzyme's environment by freezing and thawing the preparation also resulted in a loss of enzymatic activity, which was restored by added exogenous phospholipids.The alkenyl‐GPC hydrolase was inhibited by imidazole and some of its derivatives. Histidine and N‐acetyl histidine did not inhibit the enzyme, presumably due to the presence of a negative charge on the carboxyl group rather than the steric bulk of that group, since histidine methyl ester did inhibit the enzyme. Kinetic evidence showed imidazole to be a competitive inhibitor. The enzymatic activity of imidazole‐treated microsomes also increased following addition of exogenous phospholipids. Imidazole inhibition differed from the phospholipase A‐inactivation in that it was partially reversed by KCl, but not by sucrose. Imidazole did not inhibit other microsomal enzymes tested, indicating that it is not a general inhibitor of membrane‐associated enzymes.
Quantitative determination of alk‐1‐enyl‐ and alkyl‐glyceryl ethers in neutral lipids and phospholipids
Authors: Wood Randall , Snyder Fred 
Published: November 2006

AbstractA quantitative method for the simultaneous determination of alk‐l‐enyl‐ and alkyl‐glyceryl ethers is described. Complete hydrogenolysis of carboxylate and phosphate esters of neutral lipids and phospholipids was achieved with lithium aluminum hydride. The hydrogenolysis products of the glyceryl ether containing lipids, alk‐l‐enyl‐ and alkyl‐glyceryl ethers and alcohols, were identified by thin‐layer chromatography (TLC), gas‐liquid chromatography (GLC), and infrared spectroscopy. The alk‐l‐enyl‐ and alkyl‐glyceryl ethers were quantitated by TLC photodensitometry. The specificity of this method can also be extended when used in conjunction with GLC, ion‐complexing TLC, zonal scanning, and autoradiography to study composition, isomeric form, and the biosynthesis of glyceryl ethers in neutral and phospholipids.The percentage of alk‐l‐enyl‐ and alkyl‐glyceryl ethers in bothtthe neutral lipids and phospholipids of various rat tissues was determined by the described method. Glyceryl ether glycerides represent 0.3–1.2% of the total neutral lipids whereas the glyceryl ether phosphatides of brain, heart, marrow, muscle, and spleen represent 4.5–12.0% of their total phospholipids. Higher concentrations of glyceryl alkyl than of alk‐l‐enyl ethers were found in the neutral lipids whereas the glyceryl alk‐l‐enyl ethers were found to predominate in the phospholipids.
The effect of a polyunsaturated diet upon adipose‐tissue fatty acids in young coronary males. A five‐year cohort study
Authors: Fleischman Alan I. , Hayton Thomas , Bierenbaum Marvin L. , Watson Portia 
Published: November 2006

AbstractThe fatty acid composition in the adipose tissue of 38 electrocardiographycally confirmed coronary males, mean age 43.7 years, at ideal weight on a 30%‐of‐calories controlled‐fat diet, containing approximately 11.4% of calories as linoleic acid, was studied. The initial linoleic acid concentration in the adipose tissue was approximately 11 mole % of total fatty acids; for approximately the first 12 months it rose slightly and then rapidly increased to about 20% after 24 months. The overall response is sigmoidal in form and fits the equation: 1/y=0.025+0.066 (0.975)x in which y represents the adipose tissue linoleate as mole percentage of total adipose tissue fatty acids and x is the time in months.The relative increase in linoleic acid is not attributable to a decrease in any specific fatty acid.
Metabolism of lipids in rat testes: Interconversions and incorporation of linoleic acid into lipid classes
Authors: Nakamura Masami , Privett O. S. 
Published: November 2006

AbstractStudies are reported on the mode of incorporation of linoleic acid into lipid classes of testicular lipids. 1‐14C‐linoleic acid was injected into the testes of adult rats of the Sprague‐Dawley strain. Groups of animals were killed at 1, 3, 6, 12, 24 and 48 hr after injections of the radioactive linoleic acid. The testes of each animal and livers of some animals were excised. Fatty acid and lipid class comkposition of the extracted lipids of the testes of each animal were determined as well as the distribution of radioactvity in these compounds. Radioactive linoleic acid and fatty acids derived from it by interconversion and catabolism were incorporated into all the lipid classes. Incorporation of linoleic acid into the lipid classes was much faster than its interconversion or catabolism to other fatty acids. The importance of the fatty acid pool in the mode of incorporation of the fatty acids into the lipid classes is demonstrated.