bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dietary fish oil and cytochrome P‐450 monooxygenase activity in rat liver and kidney
Authors: Valdes Eleva , Vega Patricio , Avalos Nicolas , Orellana Myriam 
Published: November 2006

AbstractLauric acid hydroxylation and aminopyrineN‐demethylation were studied in kidney and liver microsomes from rats treated with fish oil. Different doses of fish oil containing 20% eicosapentaenoic acid and 10% docosahexaenoic acid were provided daily to the rats for seven days. In all the groups studied, the lauric acid metabolism was higher in kidney microsomes and the aminopyrine metabolism in the liver microsomes. Although no effect on the renal cytochrome P‐450 concentration was detectable, all four fish oil doses increased the hepatic concentration of cytochrome P‐450 by a mean 27%. The higher fish oil doses used increased the renal and hepatic microsomal metabolism of aminopyrine. The lauric acid metabolism was increased by fish oil only in the liver. Fish oil, a known inducer of fatty acid peroxisomal β‐oxidation, also induced microsomal activity. These results show that liver and kidney respond in different ways to dietary factors such as fish oil. In addition, our study would suggest that fish oil increased the activity of two different families of liver cytochrome P‐450. The activity of kidney lauric acid 11‐ and 12‐hydroxylation, however, was not modulated by fish oil.
Effects of peroxidative stress and age on the concentration of a deoxyguanosine‐malondialdehyde adduct in rat DNA
Authors: Draper Harold H. , Agarwal Sanjiv , Voparil Nelson Dagmar E. , Wee Jae Joon , Ghoshal A. K. , Farber Emmanual 
Published: November 2006

AbstractThe effect of age and peroxidative stress on the concentration of a deoxyguanosine malondialdehyde adduct (dG‐MDA) in rat tissues was investigated. Vitamin E deficiency had not effect on the dG‐MDA content of liver DNA in rats fed a diet containing 10% corn oil. When 2% cod liver oil was added to this diet, the dG‐MDA content of liver DNA doubled in the positive controls fed a high level of vitamin E (100 ppm dl‐α‐tocopherol), and there was a further increase when vitamin E was deleted. Neither iron nitrilotriacetate administration nor choline deficiency had any effect on the dG‐MDA content of liver DNA. Carbon tetrachloride had a lowering effect. The failure of iron or carbon tetrachloride administration and of vitamin E deficiency to increase liver dG‐MDA is consistent with their failure in previous experiments to affect the urinary excretion of dG‐MDA. In contrast, these forms of peroxidative stress produce large increments in the urinary excretion of MDA adducts with lysine, reflecting increased formation and degradation of MDA‐modified proteins. DNA appears to be protected from modification by MDA produced at extranuclear sites. The frequency of dG‐MDA in different tissues of 4‐month‐old rats varied markedly: brain ≫ liver > kidneys and testes. Higher concentrations of dG‐MDA were found in the liver and kidneys, but not the testes, of 25‐month‐old rats. The determinants of the concentration of dG‐MDA in DNA merit further investigation.
The relationship between the structure of monoalkyl branched saturated fatty acids and some physical properties
Authors: Svensson Leif , Hansson Ulf , Gronowitz Salo , Klingstedt Tomas 
Published: November 2006

AbstractThe gel point and the refractive index of monoalkyl branched saturated fatty acids were determined and related to the structure of the acids. A three‐factor central composite face‐centered design was constructed where the three variables were the length of the main chain, the branching position and the length of the side chain. Second‐order models were calculated in which the two properties were related to the structure. In order to confirm the validity of the models, two additional fatty acids were analyzed. The gel point was found to be proportional to the length of the main chain and the square of the branching position whereas the refractive index was proportional to the length of both the main and the side chain and also to the square of the main chain.
3‐carboxy‐4‐nitrophenyl‐dithio‐1,1′,2‐trisnorsqualene: A site‐directed inactivator of yeast oxidosqualene cyclase
Authors: Balliano Gianni , Grosa Giorgio , Milla Paola , Viola Franca , Cattel Luigi 
Published: November 2006

AbstractThe role and location of essential thiol groups in 2,3‐oxidosqualene cyclase fromSaccharomyces cerevisiae was examined (i) by comparing inactivation properties of two known thiol reagents, 5,5′‐dithiobis(2‐nitrobenzoic acid) (DTNB) and 2‐nitro‐5‐thiocyanobenzoic acid (NTCB), with 3‐carboxy‐4‐nitrophenyl‐dithio‐1,1′,2‐trisnorsqualene (CNDT‐squalene), a new thiol reagent designed as a sitedirected inactivator of oxidosqualene cyclase and (ii) by testing the ability of the substrate to protect the enzyme against inactivation by the reagents. All reagents gave a time‐dependent inactivation following pseudo‐first order kinetics. DTNB and CNDT‐squalene showed comparable inactivation ability (Ki=0.67 and 1.21 mM), whereas NTCB was less effective (Ki=15.6 mM). Strong differences between the two most active inhibitors, DTNB and CNDT‐squalene, were observed when the enzyme was saturated with substrate prior to incubation with the thiol reagent. While substrate did not protect the enzyme against the inactivation caused by DTNB, a reduction in the inactivation ability of CNDT‐squalene was observed under protection conditions. The data suggest that the squalene‐like inactivator modifies a thiol group located at the active site of the enzyme.
General resistance to sterol biosynthesis inhibitors inSaccharomyces cerevisiae
Authors: Ladevèze Véronique , Marcireau Christophe , Delourme Didier , Karst Francis 
Published: November 2006

AbstractScreening for resistance to fenpropimorph was undertaken in order to isolate yeast mutants affected in the regulation of the ergosterol pathway. Among the mutants isolated, one bearing the recessivefen1‐1 mutation was characterized by a 1.5‐fold increase in the ergosterol level and a general resistance to sterol biosynthesis inhibitors. Thefen1‐1 mutation was linked toMAT locus on chromosome III. The measurement of enzyme activities involved in the ergosterol pathway revealed that isopentenyl diphosphate (IPP) isomerase activity was specifically increased 1.5‐fold as compared to the wild type strain. However, overexpression of IPP isomerase in the wild type strain was not by itself sufficient to lead to sterol increase or resistance to sterol biosynthesis inhibitors, showing that IPP isomerase is not a limiting step in the pathway. Thefen1‐1 mutation permits viability in aerobiosis of yeast disrupted for sterol‐14 reductase in absence of exogenous ergosterol supplementation, whereas the corresponding strain bearing the wild typeFEN1 allele grows only in anaerobiosis. This result shows that ignosterol is able to efficiently replace ergosterol as bulk membrane component and that thefen1‐1 mutation eliminates the specific ergosterol requirement in yeast.
Parameters influencing cholesterol oxidation
Authors: Kim S. K. , Nawar W. W. 
Published: November 2006

AbstractThe purpose of this study was to investigate the effects of temperature, oxidation time, presence of water, pH, type of buffer and form of substrate used on cholesterol oxidation. Microcrystalline cholesterol films, both solid and melted, and aqueous suspensions of film fragments were used as substrates. Use of dispersing agents was avoided. Quantitative analysis of the unaltered substrate and the products of its autoxidation was carried out by gas chromatography over the course of oxidation. Solid cholesterol films were found to be resistant to autoxidation in the dry state. However, when heated at 125°C, a sudden increase in oxidation rate occurred at a point coinciding with the visible melting followed by a plateau of the oxidation rate. All of the autoxidation products formed underwent further decomposition. Film fragments of cholesterol oxidized at a faster rate in aqueous suspensions than when oxidized in the dry state. In aqueous suspensions, the differences in the resistance of cholesterol to oxidation were not significant within the pH range 6.0–7.4, except for the early stages of oxidation. The 7‐ketocholesterol/7‐hydroxycholesterol ratio dropped significantly with increasing pH. However, at all pH levels tested, this ratio remained relatively constant during the 6 h of heating. While the 7β‐hydroxycholesterol/7α‐hydroxycholesterol ratio was not affected by pH in the range of 6.0–7.4, at pH 7.4 a high preference was observed for the cholesterol β‐epoxide over its α‐isomer. The β/α‐epoxide ratio decreased with time of heating and with decreasing pH. The data show that the physical state of the substrate exerts a major influence on the oxidative behavior of cholesterol.
Cholesterol and 25‐hydroxycholesterol retention in specimens of liver and aorta prepared for electron microscopy. II. Effect of filipin, osmium, digitonin and saponin
Authors: Fornas E. , Renau‐Piqueras J. , Fortea A. , Mayordomo F. , Alborch E. 
Published: November 2006

AbstractSprague‐Dawley rats were injected intraperitoneally with [1α,2α(n)‐3H]cholesterol or 25‐hydroxy‐[26,27‐3H]cholesterol, and one and five days later liver and aortic tissues were fixed. The extent to which these sterols were lost from the tissues during preparation for electron microscopy (EM) was examined utilizing different fixation procedures and various protective agents. Radioactive tracers, scintillation counting and standard EM techniques were used. Although most of the procedures examined caused major lipid losses, useful fixation procedures that allow retention of cholesterol or 25‐hydroxycholesterol in liver and aortic tissues were found and are described here.
Microwave‐mediated methanolysis of lipids and activation of thin‐layer chromatographic plates
Authors: Khan Mobashsher U. , Williams John P. 
Published: November 2006

AbstractA technique is described for the methanolysis of fatty acids from acylglycerols with HCl/CH3OH or NaOH/CH3OH using a microwave oven. The esterification is rapid and complete and does not result in significant degradation of polyunsaturated fatty acids, even in the presence of oxygen. The fatty acid compositions of intact tissues were also determined using this technique. The microwave oven has also been used to condition normal silica gel and argentation thin‐layer chromatographic plates in a fraction of the time normally required.
Enteral feeding a structured lipid emulsion containing fish oil prevents the fatty liver of sepsis
Authors: Lanza‐Jacoby Susan , Phetteplace Hope , Tripp Robert 
Published: November 2006

AbstractFish oils (FO) have been shown to reduce plasma triglycerides (TG). In this study we evaluated whether enteral feeding with a structured lipid emulsion (SLE) containing FO and medium‐chain triglycerides (MCT) would prevent the hypertriglyceridemia and fatty infiltration of the liver that develops during sepsis. For five days, male Lewis rats (275–300 g) were fed intragastrically a nutritionally complete diet containing a SLE or a similar diet with a soybean oil emulsion (SOE) in place of the SLE. On the fifth day, sepsis was induced by intravenously injecting 8×107 liveEscherichia coli colonies/100 g b.w.; 24 h later the control SLE, septic SLE, control SOE, and septic SOE rats were sacrificed. Diet, but not treatment, had a significant effect on serum TG and free fatty acids (FFA). Feeding the SLE reduced the plasma FFA of the control and septic rats by more than 50% in comparison to both control and septic rats fed the SOE. Soleus muscle activity of lipoprotein lipase from the septic SLE rats was 44% higher than the control SLE rats. Soleus muscle from the septic SLE rats also had a twofold greater activity of lipoprotein lipase than the septic SOE rats. TG did not accumulate in the livers of the septic rats fed SLE when compared to the control SLE rats and the rats fed the SOE. Livers from the septic rats fed the SLE had a third of the TG that were present in the livers from the septic rats fed the SOE. The rate of incorporation of [14C]oleate into liver lipids was significantly lower in septic rats fed SLE than in those fed the SOE. TG esterification was 70% lower in the septic rats fed SLE rather than the SOE. Our findings suggest that the SLE with FO and MCT has a role in the prevention of the sepsis‐associated fatty liver by reducing the biosynthesis of liver TG.
Effect of tumor necrosis factor‐α on triglyceride and phospholipid content and fatty acid composition of liver and carcass in rats
Authors: Raina Nilima , Matsui Junichi , Cunnane Stephen C. , Jeejeebhoy Khursheed N. 
Published: November 2006

AbstractWe have previously shown that a continuous infusion of tumor necrosis factor‐α (TNF‐α) in rats results in an increase in plasma triglyceride (TG), liver protein and DNA, and at the same time a reduction in muscle protein. However, there is no information on the associated effects of TNF‐α on liver and muscle lipids. The present study, therefore, determined the effect of TNF‐α on the TG and phospholipid (PL) content and their fatty acid composition, in the liver and carcass of rats and correlated with the plasma levels of insulin, corticosterone, and catecholamaines. Total parenteral nutrition that met the daily nutrient requirements was continuously infused for 10 d through a central vein catheter in two groups of rats, one receiving infused TNF‐α (100 μg/kg/d) and a control group. Hepatic TG and PL, expressed either as mg/g dry weight or total organ content, were significantly increased in the TNF‐α‐infused group compared with controls. Livers of TNF‐α infused rats contained significantly less saturated and monounsaturated fatty acids and significantly more polyunsaturated fatty acids (PUFA) of the ω3 and ω6 series than controls. The carcass, on the other hand, contained significantly more monounsaturated and significantly less polyunsaturated fatty acids of the ω6 series than controls. There were no changes in corticosterone level. Although plasma glucose levels were comparable between control and TNF‐α infused rats, the latter had a marked increase in insulin levels, demonstrating insulin resistance. In addition TNF‐α infused rats had raised norepinephrine levels. The fall in carcass and rise in liver TG and PL are consistent with the presence of insulin resistance and raised norepinephrine levels. However, the increase in PUFA content of the liver, especially the increase in 20∶4ω6 levels in liver PL and TG, is likely to be the effect of TNF‐α and suggests increased activity of Δ5‐desaturase.
Critical analysis of phospholipid hydrolyzing activities in ripening tomato fruits. Study by spectrofluorimetry and high‐performance liquid chromatography
Authors: Rouet‐Mayer Marie‐Aude , Valentova Olga , Simond‐Côte Elizabeth , Daussant Jean , Thévenot Claudine 
Published: November 2006

AbstractUsing the spectrofluorimetric method described by Wittenaueret al. [Wittenauer, L.A., Shirai, K., Jackson, R.L., and Johnson, J.D. (1984)Biochem. Biophys. Res. Commun. 118, 894–901] for phospholipase A2 (PLA2) measurement, we have detected a phospholipase activity in Ailsa Craig and in mutantrin tomatoes at their normal harvest time (mature green stage). This activity in Ailsa Craig tomatoes increased at the beginning of fruit ripening (green‐orange stage) and then decreased slowly. The decrease in activity, however, was greater when ripening occurred after tomato picking at normal harvest time than when ripening occurred on tomato plants. This phospholipase activity was always higher inrin tomatoes than in normal ones. Thin‐layer chromatography of compounds obtained after incubation of tomato extract demonstrated a decrease in the substrate 1‐acyl‐2‐{6[(7‐nitro‐2,1,3, benzoxadiazol‐4‐yl)amino]‐caproyl}‐sn‐glycero‐3‐phosphocholine (C6‐NBD‐PC), and an increase in one product (NBD‐aminohexanoic acid), but failed to detect the second product (1‐acyl‐sn‐glycero‐3‐phosphocholine). We, therefore, developed a new one‐step method for separation and quantification of a mixture of phospholipids and other lipids, using straight‐phase‐high‐performance liquid chromatography with light‐scattering detection. This method detected another fatty acid‐releasing activity in enzyme extract from green‐orange tomatoes. This lipolytic enzyme (or family of enzymes) slowly produced free fatty acids when 1‐oleoyl‐sn‐glycero‐3‐phosphocholine was added as substrate. The production of fatty acids was stoichiometric and more rapid when 1‐oleoyl‐sn‐glycero‐3‐phosphate and 1‐oleoyl‐sn‐glycerol were used as substrates. On the other hand, the same tomato extract was unable to hydrolyze 1,2‐dioleoyl‐sn‐glycero‐3‐phosphate and 1,2‐dioleoyl‐sn‐glycerol. Crude tomato extract exhibited lipid acyl hydrolase activity according to the definition of Galliard [Galliard, T. (1979), inAdvances in the Biochemistry and Physiology of Plant Lipids (Appelqvist, L.A., and Liljenberg, C. eds.), pp. 121–132, Elsevier, Amsterdam]. But in order to demonstrate whether tomato extract contains PLA2 activity and/or lysophospholipase activity, further work on purified tomato extract will be necessary.
Substrate specificity of the lipase fromCandida parapsilosis
Authors: Briand Delphine , Dubreucq Eric , Grimaud Jean , Galzy Pierre 
Published: November 2006

AbstractSubstrate specificity of the acyltransferase activity of the lipase (EC 3.1.1.3) fromCandida parapsilosis CBS 604 was studied in aqueous media. The specificity toward both acid and alcohol parts of a large number of acylglycerols and aliphatic esters was investigated. This lipase showed a high activity in the presence of esters with long‐chain fatty acids and particularly unsaturated fatty acids with acis‐Δ9 double bond. It was observed that the activity profile depended not only on the alcohol part of the acyl ester, but also on the temperature of the reactant medium. The best lipid substrates had their melting point between −40 to +20°C, 14 to 18 carbon atoms in the acyl group and 1 to 4 carbon atoms in the alkyl group. The enzyme, defined as an acyltransferase in a previous paper, showed a high affinity for primary and secondary alcohols with a short carbon chain (1 to 5 carbon atoms) as acyl acceptors. The influence of free alcohols in the reactant medium on the hydrolysis and alcoholysis activities of the enzyme is discussed. Two phenomena seem to be involved, depending on the alcohol: competition with water for the acyltransfer reaction and lipid substrate dilution when the alcohol places at the oil/water interface.
Octadecatrienoic acids as the substrates for the key enzymes in glycerolipid biosynthesis and fatty acid oxidation in rat liver
Authors: Ide Takashi , Murata Masakazu , Sugano Michihiro 
Published: November 2006

AbstractThe activities of key enzymes in glycerolipid biosynthesis and fatty acid oxidation were compared using CoA esters of naturally occurring positional isomers of octadecatrienoic acids (18∶3) as the substrates. The trienoic acids employed were 9,12,15–18∶3 (α‐18∶3), 6,9,12–18∶3 (γ‐18∶3), and 5,9,12–18∶3 (pinolenic acid which is a fatty acid contained in pine seed oil, po‐18∶3). The activities of microsomal glycerol 3‐phosphate acyltransferase obtained with various 18∶3 were only slightly lower than or comparable with those obtained with palmitic (16∶0), oleic (18∶1), and linoleic (18∶2) acids. Mitochondrial glycerol 3‐phosphate acyltransferase was exclusively specific for saturated fatty acyl‐CoA. The activities of microsomal diacylglycerol acyltransferase measured with various polyunsaturated fatty acyl‐CoAs were significantly lower than those obtained with 16∶0‐ and 18∶1‐CoAs. Among the polyunsaturated fatty acids, γ‐18∶3 gave the distinctly low activity. The Vmax values of the mitochondrial carnitine palmitoyltransferase I were significantly higher with α‐18∶3 and po‐18∶3 but not γ‐18∶3, than with 16∶0 and 18∶2, while the apparent Km values were the same irrespective of the types of acyl‐CoA used except for the distinctly low value obtained with γ‐18∶3. The response to an inhibitor of the acyltransferase reaction, malonyl‐CoA, was appreciably exaggerated with 18∶2, α‐18∶3, and po‐18∶3 more than with 16∶0 and 18∶1. However, the response with γ‐18∶3 was the same as with 16∶0. Thus, some of glycerolipid biosynthesis and fatty acid oxidation enzymes could discriminate not only the differences in the degree of unsaturation of fatty acids but also the positional distribution of double bond among the naturally occurring 18∶3 acids.
Inhibition of cholesterol esterification in macrophages and vascular smooth muscle foam cells: Evaluation of E5324, an Acyl‐CoA cholesterol acyltransferase inhibitor
Authors: Nicholson Andrew C. , Pomerantz Kenneth B. , Fujimori Tohru , Hajjar David P. 
Published: November 2006

AbstractCholesteryl esters (CE) comprise the principal lipid class that accumulates within macrophages and smooth muscle cells of the atherosclerotic lesion. Acyl‐CoA cholesterol acyl‐transferase (ACAT) is the major enzyme responsible for esterification of intracellular cholesterol. We evaluated the ability of E5324 (n‐butyl‐N″‐[‐2‐[3‐(5‐ethyl‐4‐phenyl‐1H‐imidazol‐1‐yl)propoxyl]‐6‐methyl‐phenyllurea), a novel, orally absorbable ACAT inhibitor, to inhibit esterification of fatty acids to cholesterol and CE accumulation in macrophages and in smooth muscle cells. E5324 significantly inhibited cholesterol esterification in rat aortic smooth muscle cells and in macrophages. In addition, E5324 reduced the cellular mass of CE, the significant measure of the efficacy of drugs designed to modulate cholesterol metabolism. E5324 treatment of macrophages exposed to acetylated low‐density lipoprotein reduced CE mass by 97%, and treatment of lipid‐loaded smooth muscle cells reduced CE mass by 29%. Although free cholesterol increased approximately twofold, this free cholesterol would presumably be accessible to the membrane for effluxin vivo (reverse cholesterol transport). These results demonstrate that E5324 can inhibit cholesterol esterification and CE mass in atherosclerotic foam cells, derived from either macrophages or arterial smooth muscle cells.
Synthesis of linoleate and α‐linolenate by chain elongation in the rat
Authors: Cunnane Stephen C. , Ryan Mary Ann , Craig Kerr S. , Brookes Steven , Koletzko Berthold , Demmelmair Hans , Singer Janet , Kyle David J. 
Published: November 2006

AbstractThe objective was to determine whether rats could synthesize longer chain polyunsaturates from hexadecadienoate (16∶2n−6) and hexadecatrienoate (16∶3n−3). Rats were gavaged with uniformly13C‐labelled hexadecadienoate or hexadecatrienoate, euthanized 24 h later, and total lipids were extracted from liver and carcass. Gas chromatogrpahy/combustion/isotope ratio mass spectrometry was used to measure13C levels in individual liver, carcass, and whole body fatty acids.13C Enrichment was present in desaturated and chain‐elongated polyunsaturates, including linoleate, arachidonate, α‐linolenate, and docosahexaenoate at 12–13% of the dose of tracer given.13C Enrichment from hexadecatrienoate was highest in carcass and liver α‐linolenate, representing 3.5 and 17.9% of the total α‐linolenate pool, respectively. For linoleate, arachidonate, or docosahexaenoate, the contribution of13C did not exceed 0.2% of the total body pool. Green leafy vegetables common in the human diet were shown to contain up to 1.2% of total fatty acids as hexadecadienoate and 11.6% as hexadecatrienoate. Hence, humans consuming green vegetables probably synthesize a small proportion of their total body content of linoleate and α‐linolenate.