bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reduction of polyunsaturated fatty acid hydroperoxides by human brain glutathione peroxidase
Authors: Kaplan E. , Ansari K. 
Published: November 2006

AbstractGlutathione peroxidase (GSHPx) activity in the normal human brain was investigated using lipid hydroperoxides as substrates. Samples were obtained from autopsied frontal gray matter of 5 normal human males with no known central nervous system (CNS) disease. Aliquots were homogenized in 0.9% NaCl‐0.5% Triton X‐100, and the supernatant solution, obtained after centrifugation at 105,000 × g, was used for GSHPx assay. Glutathione peroxidase was measured by following the oxidation of NADPH at 340 nm. Hydroperoxides of linoleic, linolenic, gamma linolenic, 11,14 eicosodienoic, homo gamma linolenic, arachidonic, docosotetraenoic and docosohexaenoic acids were prepared and used as substrates. All these hydroperoxides were reduced by the brain GSHPx system, but at different rates. Gamma linolenic and docosotetraenoic hydroperoxides were reduced rapidly, whereas the peroxides of docosohexaenoic and 11,14 eicosodienoic were reduced at the lowest rate. Arachidonic hydroperoxide had the highest affinity for the enzyme and linolenic the lowest. Our results suggest that the brain GSHPx system is capable of reducing hydroperoxides of polyunsaturated fatty acids.
Analysis of autoxidized fats by gas chromatography‐mass spectrometry. IX. Homolytic vs. Heterolytic cleavage of primary and secondary oxidation products
Authors: Frankel E. N. , Neff W. E. , Selke E. 
Published: November 2006

AbstractTo elucidate the genesis of volatile lipid oxidation products, thermal homolytic and acid heterolytic decomposition processes were compared. Secondary oxidation products were decomposed thermally (200 C), and the volatiles formed were identified by capillary gas chromatography‐mass spectrometry (GC‐MS). Oxidation products also were decomposed in the presence of HCl‐methanol, and the resulting dimethyl acetals were identified by GC‐MS. The volatile thermal decomposition products were those expected by homolytic β‐scission on both sides of the hydroperoxide group. No dialdehydes were identified under our thermal decomposition conditions. In contrast, the acetals formed by acid decomposition were those expected by selective heterolytic scission between the hydroperoxide group and the allylic double bond. Dialdehydes identified from acid decomposition of cyclic peroxides and dihydroperoxides included malonaldehyde and 2,4‐hexadienedial.
The purification of fatty acid methyl esters by high pressure liquid chromatography
Authors: Bascetta Emanuele , Gunstone Frank D. , Scrimgeour Charles M. 
Published: November 2006

AbstractProcedures are described for the rapid purification of gram quantities of methyl oleate, methyl linoleate, methyl α‐ and γ‐linolenates and methyl ricinoleate from appropriate natural oils by high pressure liquid chromatography (HPLC).
Essential fatty acids in plasma, red blood cells and liver phospholipids in common laboratory animals as compared to humans
Authors: Horrobin David F. , Huang Y. ‐S. , Cunnane S. C. , Manku M. S. 
Published: November 2006

AbstractEssential fatty acids were estimated in plasma, red blood cells and liver total phospholipids in rats, mice, hamsters, guinea pigs, rabbits and humans. There were large species differences, suggesting that different species levels should be borne in mind when choosing an animal for a particular study. The 2 species most susceptible to atheroma, the guinea pig and the rabbit, had very high levels of linoleic acid and low levels of linoleic acid metabolites. n−3 fatty acid levels were low in guinea pigs and rabbits and the ratio of n−3 to n−6 fatty acids also was low in the rat. Mice and hamsters had the highest n−3 levels, suggesting they may be the best species to use for studies on the roles of n−3 essential fatty acids. Mice and hamsters and, in some respect rats, were closest to humans in their fatty acid patterns.
Influence of cholesterol feeding and dietary restriction on cholesterol absorption in rabbits
Authors: Corraze G. , Lacombe C. , Nibbelink M. 
Published: November 2006

AbstractPlasma cholesterol and cholesterol absorption were measured in rabbits given either a standard or cholesterol‐rich diet which were fed either ad libitum or reduced to 50% of the control ration. The results confirmed the aggravating effect of dietary restriction on the plama cholesterol response to cholesterol feeding. Hypercholesterolemia was doubled when cholesterol feeding was associated with reduced dietary intake. The percentage of cholesterol absorbed increased significantly in cholesterolfed rabbits on normal caloric ration, while dietary restriction had no effect on this parameter either with the standard or the cholesterol‐rich diet. These data indicate that the mechanisms by which plasma cholesterol increases in response to cholesterol feeding involve increased cholesterol absorption. Nevertheless the aggravating effect of dietary restriction cannot be attributed to increased cholesterol absorption.
Analyses of lipids and fatty acids in ripe roes of some Northwest European marine fish
Authors: Tocher Douglas R. , Sargent John R. 
Published: November 2006

AbstractLipid class analyses and fatty acid analyses of neutral and polar lipids were carried out on ripe roes of herring, cod, haddock, whiting, saithe, sand eel and capelin. Total lipid was 10–26% of roe dry weight. The species with the highest total lipid, sand eel and capelin, also had the highest percentage of neutral lipid in total lipid, 77% and 49% respectively. In the other species, phospholipids accounted for 62–77% of roe total lipid. Both the neutral lipids, and especially the phospholipids, of all species were very unsaturated because of high concentrations of (n−3) polyunsaturated fatty acids (PUFA), frequently amounting to 50% of the total egg lipid. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) had similar fatty acid compositions in all species, with an average ratio (n−3)/(n−6) of ca. 20∶1. Phosphatidylinositol (PI) consistently had high concentrations of 18∶0 and 20∶4 (n−6) with an average ratio of (n−3)/(n−6) of 1.8∶1. Requirements for high levels of (n−3) PUFA in the embryonic and early larval development stages of marine fish are suggested as is a special role for the 20∶4(n−6) in PI.
Sterol metabolism in the nematodeCaenorhabditis elegans
Authors: Chitwood David J. , Lusby William R. , Lozano Ruben , Thompson Malcolm J. , Svoboda James A. 
Published: November 2006

AbstractThe metabolism of various dietary sterols and the effects of an azasteroid on sitosterol metabolism in the free‐living nematodeCaenorhabditis elegans was investigated. The major unesterified sterols ofC. elegans in media supplemented with sitosterol, cholesterol or desmosterol included 7‐dehydrocholesterol (66.5%, 40.5%, 31.2%, respectively), cholesterol (6.7%, 52.3%, 26.9%), lathosterol (4.4%, 3.6%, 1.7%) and 4α‐methylcholest‐8(14)‐en‐3β‐ol (4.2%, 2.1%, 3.8%). Esterified sterols, representing less than 20% of the total sterols, were somewhat similar except for a significantly higher relative content of 4α‐methylcholest‐8(14)‐en‐3β‐ol (23.3%, 23.4%, 10.6%). ThusC. elegans not only removes the substituent at C24 of dietary sitosterol but possesses the unusual ability to produce significant quantities of 4α‐methylsterols. WhenC. elegans was propagated in medium supplemented with sitosterol plus 5 μg/ml of 25‐azacoprostane hydrochloride, the azasteroid strongly interfered with reproduction and motility ofC. elegans and strongly inhibited the Δ24‐sterol reductase enzyme system; excluding sitosterol, the major free sterols of azacoprostane‐treatedC. elegans were cholesta‐5, 7, 24‐trien‐3β‐ol (47.9%), desmosterol (9.4%), fucosterol (2.1%) and cholesta‐7,24‐dien‐3β‐ol (2.0%). These 4 sterols are likely intermediates in the metabolism of sitosterol inC. elegans.
Preferential metabolism of linoleic acid by five‐day‐old barley shoots
Authors: Nabors Lola A. , Morgan Marjorie S. , Newman David W. , Jaworski Jan G. 
Published: November 2006

AbstractThe degradation of exogenous radioactively labeled fatty acids by 5‐day‐old barley shoots was examined. [1‐14C] Linoleic acid was observed to be degraded 7 times faster than [1‐14C] oleic acid and 5 times faster than [1‐14C] palmitic acid. The pathway of degradation was determined by identifying the water‐soluble products and determined to be β‐oxidation. During a 15 min incubation, the barley shoots took up 0.91 nmol/g fresh wt of linoleic acid, of which 0.16 nmol/g fresh wt was incorporated into glutamic acid, 0.07 nmol/g fresh wt into succinic acid and 0.002 nmol/g fresh wt into carbohydrates. By 30 min, additional TCA cycle intermediates, especially malic acid, were detected. Palmitic acid and oleic acid were broken down to the same products. The rates of uptake and the distribution of label into lipids were determined. The uptake of label by the tissue was similar for all 3 fatty acid substrates. Label from linoleic, oleic and palmitic acids was found to be incorporated into similar lipids, primarily phosphatidylcholine (PC), and the extent of incorporation was comparable. Although all 3 fatty acid substrates were broken down by β‐oxidation, the reason for the more rapid degradation of linoleic acid was not established. It does not appear to be related to uptake of substrate or incorporation of label into lipids.
A possible regulatory role of squalene epoxidase in chinese hamster ovary cells
Authors: Eilenberg Haviva , Shechter Ishaiahu 
Published: November 2006

AbstractGrowth of Chinese Hamster Ovary (CHO) cells in the presence of 20% lipid depleted serum (LDS) for only 2 hr results in an increase in the synthesis of [14C] sterols from [14C] mevalonate and from [14C] squalene compared with cells grown under normal growth conditions in the presence of 10% fetal calf serum (FCS). This enhanced sterol synthesis increases with time of exposure of the cells to LDS. However, exposing these cells for time periods up to 42.5 hr to a growth medium containing 20% LDS did not result in enhanced [14C] sterol synthesis from [14C] 2,3‐oxidosqualene. Incubation of these cells with [14C] mevalonate resulted in the accumulation of [14C] squalene regardless of the presence of either LDS or FCS. These results suggest that squalene epoxidase is a regulatory enzyme in the cholesterol biosynthetic pathway in CHO.
Selective oxidation of steroidal allylic alcohols using pyrazole and pyridinium chlorochoromate
Authors: Parish Edward J. , Chitrakorn Sarawanee , Lowery Susan 
Published: November 2006

AbastractThis paper presents a modified method for the selective oxidation of allylic alchols. Pyrazole, when used with pyridinium chlorochromate, is a mild and useful reagent system for the rapid and selective oxidation of steroidal allylic alcohols to the corresponding α, β‐unsaturated ketones. The reaction of each substrate was carried out by adding the oxidant to a dry methylene chloride solution containing pyrazole and an allylic alchol. This report is the first on the use of pyrazole to augment selective oxidation by a chronium (VI) reagent.
Analytic ultracentrifuge calibration and determination of lipoprotein‐specific refractive increments
Authors: Kahlon Talwinder S. , Adamson Gerald L. , Glines Laura A. , Lindgren Frank T. , Laskaris Marie A. , Shore Virgie G. 
Published: November 2006

AbstractAccurate quantification of the major classes and subfractions of human serum lipoproteins is an important analytical need in the characterization and evaluation of therapy of lipid and lipoprotein abnormalities. For calibrating the analytic ultracentrifuge (AnUC), we routinely use a Beckman calibration wedge cell with parallel scribed lines 1 cm apart. Such a cell gives a rectangular pattern in the schlieren diagram, which determines magnification and also provides an area corresponding to an invariant refractive increment. We have independently validated this wedge calibration cell using a special boundary‐forming cell in which 1.174% sucrose is overlayered with distilled water. Comparing wedge cell area with extrapolated zero time boundary area refractive increment gives agreement to within less than 1%, corresponding to a refractive increment error of ±0.00002 Δn. Complete calibration for AnUC analysis of lipoproteins also requires accurate determination of the specific refractive increments (SRI) of the major lipoprotein classes, namely low density lipoprotein (LDL) and high density lipoprotein (HDL). These are measured in the density in which they are analyzed, i.e., 1.061 g/ml for LDL and 1.200 g/ml for HDL. Five fresh serum samples were fractionated for total LDL and total HDL and their SRI determined. Total lipoprotein mass was determined using precise CHN elemental analysis and compositional analyses. The results yielded corrected SRI of 0.00142 and 0.00135 Δn/g/100 ml for LDL and HDL. Thus, our current values using 0.00154 and 0.00149 Δn/g/100 ml underestimate LDL and HDL by 9% and 11%. Corrections of all previous LDL and HDL AnUC data can be made using appropriate factors of 1.087 and 1.106.
Plasma and lipoprotein lipid responses to four hypolipid drugs
Authors: Hazzard William R. , Wahl Patricia W. , Gagne Claude , Applebaum‐Bowden Deborah , Warnick G. Russell , Albers John J. 
Published: November 2006

AbstractThe responses of 14 hyperlipidemic subjects to 4 hypolipidemic agents were compared by measureing cholesterol and triglyceride in whole plasma, very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) monthly for 2 months before and 3 months during treatment with each of 4 drugs: clofibrate, 2 g/d; colestipol, 20 g/d; para‐aminosalicylic acid‐ascorbate (PAS‐C), 6–8 g/d; and oxandrolone, 7.5 mg/d. Lipid responses proved to be stable by the first monthly evaluation both off and on each drug. Mean adherence was high and similar for all agents (81–92% of the prescribed dose). Clofibrate was associated with significant decreases in mean plasma cholesterol (−16%, p<.01), plasma triglyceride (−51%, p<.005), VLDL‐cholesterol (−61%, p<.005) and VLDL‐triglyceride (−61%, P<.005), while HDL cholesterol increased (+20%, p<.01), and the LDL‐cholesterol/HDL ratio declined (−24%, p<.05). Colestipol was associated with decreases in mean plasma cholesterol (−15%, p<.01) and LDL‐cholesterol (−22%, p<.05), while VLDL‐triglyceride increased (+41%, p<.05), and the LDL‐cholesterol/HDL‐cholesterol ratio declined (−25%, p<.05). PAS‐C was associated with decreases in VLDL‐cholesterol (−30%, p<.05), and VLDL‐triglyceride (−29%, p<.05), while the LDL‐cholesterol/HDL‐cholesterol ratio remained unchanged. Oxandrolone was associated with increases in mean plasma cholesterol (+7%, p<.05), LDL‐cholesterol (+45%, p<.005 [+25% excluding one subject who increased 298%]), and LDL‐triglyceride (+24%, p<.01), while decreases occurred in plasma triglyceride (−31%, p<.05), VLDL‐cholesterol (−26%, p<.05), VLDL‐triglyceride (−42%, p<.005), HDL‐cholesterol (−45%, p<.005), and HDL‐triglyceride (−43%, p<.01). The mean LDL‐cholesterol/HDL‐cholesterol ratio increased by 109% (p<.005), reflecting the reciprocal changes in LDL and HDL. Thus, while both clofibrate and colestipol were associated with significant, equivalent reductions in theoretical atherogenic risk, oxandrolone produced a net effect that was not only adverse but 4 times that magnitude, suggesting caution in its long‐term use, even for the management of hypertriglyceridemia.
Iodothyronines: Oxidative deiodination by hemoglobin and inhibition of lipid peroxidation
Authors: Tseng Yueh‐Chu L. , Latham Keith R. 
Published: November 2006

AbstractPurified rat hemoglobin catalyzes the oxidative degradation of iodothyronines to form iodide and an iodine‐containing intermediate that reacts with protein. Hemoglobin also catalyzes peroxidation of linoleic acid. These observations are consistent with the reported intrinsic peroxidase activity of hemoglobin and other heme‐proteins. However, incubations containing both linoleic acid and an iodothyronine produced a surprising result: deiodination was stimulated rather than competitively inhibited. In contrast, linoleic‐acid peroxidation was inhibited by iodothyronines. Thus, low levels of iodothyronines (2.6×10−7M) are effective inhibitors of linoleic‐acid peroxidation. Thyroxine and reverse T3 were found to be more effective in this antioxidant activity than vitamin E, glutathione, ascorbic acid and DTT. Since linoleic‐acid peroxidation proceeds by a propagating free‐radical mechanism, we have concluded that iodothyronines can effectively terminate the free‐radical chain reaction to become oxidatively deiodinated. Consistent with this antioxidant mechanism, reverse T3 is effective in preserving red cell membranes as measured by the inhibition of erythrocyte hemolysis.
Restriction of maternal food intake inhibits fatty acid activation in developing rat hearts
Authors: Menon Nirmala K. , Dhopeshwarkar Govind A. , Mead James F. 
Published: November 2006

AbstractWe studied the effect of restricting the diet of pregnant and lactating rats on the β‐oxidation of fatty acids by the developing heart in suckling pups. Control pregnant rats were fed a stock diet ad libitum. For the experimental group, food was restricted to half of the control intake on the seventh day of pregnancy and continued through lactation. The pups on the restricted diet were significantly smaller than the controls. At postnatal days 5, 14 and 21, the β‐oxidation of [1‐14C] palmitate by heart homogenates was determined in the presence of ATP, carnitine and CoA. At day 21, the production of14CO2 was 60% lower in the group on the restricted diet. Consequently, the possibility of inhibiting activation or intramitochondrial transport of fatty acids by heart mitochondria was studied in vitro using [1‐14C] palmitate, [1‐14C] palmitoyl CoA and [1‐14C] palmitoyl carnitine. With [1‐14C]‐palmitate, the rate of14CO2 produced was 2464±317 cpm/mg protein/min for the control and 1682±91 for the restricted diet group. With [1‐14C] palmitoyl CoA and [1‐14C] palmitoyl carnitine, the oxidation rate of the experimental group was similar to control values, showing clearly that the inhibition of oxidation was from a problem with activation. A significant decrease in palmitoyl CoA synthetase activity in the heart homogenates and mitochondria of the diet‐restricted pups took place.
Inhibition of the hormone‐sensitive lipase in adipose tissue by long‐chain fatty acyl coenzyme A
Authors: Severson David L. , Hurley Brenda 
Published: November 2006

AbstractThe effects of free fatty acids and fatty acyl esters of coenzyme A and carnitine on the activity of a hormone‐sensitive lipase preparation made from pigeon adipose tissue were determined. Oleic acid (100 μM) resulted in a 40% inhibition of lipase activity A more potent inhibition of lipase activity was seen with long‐chain fatty acyl CoA compounds. The concentration required for half‐maximal inhibition with oleoyl CoA and palmitoyl CoA was 25–40 μM, whereas palmitoyl carnitine stimulated lipase activity. Activated lipase preparations (preincubated with Mg2+, ATP, cyclic AMP and protein kinase) were 4–6 times more sensitive to inhibition by oleoyl CoA than were nonactivated preparations. An increase in cellular levels of fatty acyl coenzyme A could, therefore, contribute to the feedback inhibition of lipolysis in adipose tissue.
Alcohol ingestion and levels of hepatic fatty acid synthetase and stearoyl‐CoA desaturase activities in rats
Authors: Rao G. Ananda , Lew Gail , Larkin Edward C. 
Published: November 2006

AbstractMale Sprague‐Dawley rats were fed, ad libitum for 30 days, a fat‐free (FF) liquid diet containing 34% of the calories as ethanol or a control FF diet in which alcohol was replaced by an isocaloric amount of dextrins. The cytosolic fatty acid synthetase and the microsomal stearoyl‐CoA desaturase activities in the livers of rats fed the alcohol diet were about half of those observed in the livers of control rats. The conclusion is that chronic ethanol consumption depresses the activities of these lipogenic enzymes in the liver.
Lipid, sterol and fatty acid composition of antarctic krill (Euphausia superba Dana)
Authors: Fricke H. , Gercken G. , Schreiber W. , Oehlenschläger J. 
Published: November 2006

AbstractThe lipid classes, fatty acids of total and individual lipids and sterols of Antarctic krill (Euphausia superba Dana) from two areas of the Antarctic Ocean were analyzed by thin layer chromatography (TLC), gas liquid chromatography (GLC) and gas liquid chromatography/mass spectrometry (GLC/MS). Basic differences in the lipid composition of krill from the Scotia Sea (caught in Dec. 1977) and krill from the Gerlache Strait (caught in Mar. 1981) were not observed. The main lipid classes found were: phosphatidylcholine (PC) (33–36%), phosphatidylethanolamine (PE) (5–6%), triacylglycerol (TG) (33–40%), free fatty acids (FFA) (8–16%) and sterols (1.4–1.7%). Wax esters and sterol esters were present only in traces. More than 50 fatty acids could be identified using GLC/MS, the major ones being 14∶0, 16∶0, 16∶1(n−7), 18∶1(n−9), 18∶1(n−7), 20∶5(n−3) and 22∶6(n−3). Phytanic acid was found in a concentration of 3% of total fatty acids. Short, medium‐chain and hydroxy fatty acids (C≤10) were not detectable. The sterol fraction consisted of cholesterol, desmosterol and 22‐dehydrocholesterol.
Comparative study of lipogenic enzymes in several vertebrates
Authors: Iritani Nobuko , Ikeda Yumiko , Fukuda Hitomi , Katsurada Akihiko 
Published: November 2006

AbstractThe liver lipogenic enzymes are compared among rats, chickens, frogs and fish. Although the apparent Km values of glucose‐6‐phosphate dehydrogenase for glucose‐6‐phosphate are not much different among all the species, those of malic enzyme for malate are much higher in chickens and fish than in rats and frogs. Glucose‐6‐phosphate dehydrogenase showed very high activities compared with malic enzyme in fish liver, and malic enzyme showed high activities in chicken liver. Although the apparent Km values of acetyl‐CoA carboxylase and fatty acid synthetase for substrates are in the same range among all the animals, the activity of acetyl‐CoA carboxylase seems to be extremely low in fish and frog livers, and that of fatty acid synthetase is low in frog livers only. In addition, the apparent Km values of α‐glycerophosphate acyltransferase of fish liver are very high, and the enzyme activity appears to be extremely low compared to the others. Therefore, the enzymes at the first steps of both fatty acid and glycerolipid syntheses of poikilothermos animals appear to be very low. On the other hand, the Ouchterlony double‐diffusion patterns showed that the lipogenic enzymes of chickens, frogs and fish are immunologically different from those of rats, with the exception of acetyl‐CoA carboxylase in chickens. Therefore, it is suggested that the fatty acid and glycerolipid forming systems of poikilothermos animals are quite different from those of homoiothermos and the lipogenesis is very low in poikilothermos.