bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fecal bile acid excretion and composition in response to changes in dietary wheat bran, fat and calcium in the rat
Authors: Borum Marie L. , Shehan Kathleen L. , Fromm Hans , Jahangeer Saleem , Floor Marianne K. , Alabaster Oliver 
Published: November 2006

AbstractThe effect and possible interactive influence of different dietary amounts of wheat bran, fat and calcium on the fecal excretion, concentration and composition of bile acids was studied in Fischer‐344 rats. The fecal bile acids were analyzed using gas‐liquid chromatography. Dietary wheat bran increased both total bile acid excretion and fecal weight without changes in fecal bile acid concentration. The proportion of fecal hyodeoxycholic acid decreased with increasing dietary fiber, whereas that of lithocholic and deoxycholic acids increased significantly with fiber intake. The percent content of fecal chenodeoxycholic acid did not change. Increasing dietary fat led to an increase in bile acid excretion without changes in either fecal weight or bile acid concentration. In contrast, the level of dietary calcium did not affect the total excretion of bile acids. However, since calcium increased the fecal weight, it consequently diluted bile acids and decreased their fecal concentration. Dietary fat and calcium had no influence on fecal bile acid composition. There were no interactive effects of wheat bran, fat and calcium on fecal bile acids. The finding in this study that dietary fiber, fat and calcium induce significant changes in fecal bile acids may be of relevance to the potential of bile acids to promote carcinogenesis.
Reduction in triacylglycerol levels by fish oil correlates with free fatty acid levels inad libitum fed rats
Authors: Otto David A. , Baltzell Janet K. , Wooten Joseph T. 
Published: November 2006

AbstractRats were fed (for 2 or 6 wk) purified diets containing lard (LD) or menhaden oil (MO) at two levels of dietary fat,i.e., at 11.5 and 20.8% of energy in the low fat (LF) and the medium fat (MF) diets, respectively. Following the diet period, rats were sacrificed after either an overnight fast or after uninterruptedad libitum feeding. The studies were designed to investigate the dependence of our previously reported effects of MO,i.e. the reduction of plasma free fatty acid (FFA) levels and accumulation of hepatic triacylglycerols, on the dietary fat concentration and the nutritional state of the animal at the time of sacrifice. Reductions in plasma triacylglycerol and cholesterol levels in MO‐fed relative to LD‐fed rats were observed under all conditions. FFA levels were consistently reduced by MO‐feeding at both dietary fat concentrations, but only when blood was sampled fromad libitum fed rats. Under these conditions there was a significant positive relationship between plasma FFA and triacylglycerol concentrations. Reduction in plasma FFA levels may be an additional mechanism associated with the triacylglycerol‐lowering effect of fish oil (FO). The LF and MF MO diets caused a rise in plasma glucose levels with no significant change in insulin concentration, indicating that the reduction of FFA by MO was not related to changes in insulin concentration or insulin sensitivity. The MO diets had no effect on skeletal muscle or epididymal adipose tissue lipoprotein lipase activity, demonstrating that catabolism of triacylglycerol‐rich lipoproteins contributes little, if any, to the MO‐dependent reductions of plasma triacylglycerol and FFA. The previously reported accumulation of hepatic triacylglycerols after high fat (HF; 30% of energy) MO‐feeding was not observed with the LF or MF MO diets, suggesting that the apparent direct inhibition of triacylglycerol secretion by FO imposes a rate‐limitation only when feeding HF diets.
Borage or primrose oil added to standardized diets are equivalent sources for γ‐linolenic acid in rats
Authors: Raederstorff D. , Moser U. 
Published: November 2006

AbstractThe aim of this study was to evaluate the effect of different doses and sources of dietary γ‐linolenic acid (GLA) on the tissue phospholipid fatty acid composition. Rats fed four different levels of GLA (2.3, 4.6, 6.4 and 16.2 g of GLA/kg diet) in the form of either borage oil or evening primrose oil during 6 wk were compared with animals fed corn oil. The levels of dihomo‐γ‐linolenic acid (DHLA) and GLA showed a significant dose‐related increase in liver, erythrocyte and aorta phospholipids. Moreover, the arachidonic acid/DHLA ratios in tissues decreased with increasing intake of dietary GLA. There was no significant difference in tissue GLA and DHLA levels within groups given equal amounts of dietary GLA either as borage oil or evening primrose oil. The amount of dietary GLA administered did not significantly influence prostaglandin E2 production in stimulated aortic rings and thromboxane B2 levels in serum; however, an increase in prostaglandin E1 derived from DHLA was observed in the supernatants of stimulated aorta.
Effects of 17β‐estradiol and starvation on trout plasma lipoproteins
Authors: Wallaert Charlotte , Babin Patrick J. 
Published: November 2006

AbstractAdministering 17β‐estradiol (E2) to juvenile trout results in plasma hyperlipidemia and hyperlipoproteinemia associated with significant increases in the concentrations of triglycerides (TG), free cholesterol, phospholipids, free fatty acids and proteins, both postprandial and during starvation. TG undergo the greatest increase (9 times control level 96 h after feeding). The concentration differences between E2‐treated and control trout increase during starvation, primarily by progressive decreases in the concentrations of various lipids in controls. E2‐induced hypertriglyceridemia is mainly caused by an increase in the concentration of very low density lipoproteins (VLDL) during both the postprandial period (6 times control level at 24 h) and during starvation (15 times control level at 96 h); hyperlipoproteinemia lasts up to at least 7 d after the last feeding. E2 treatment does not change the concentration of high density lipoproteins, but does increase plasma concentrations of a very high density lipoprotein, vitellogenin (VTG). In E2‐treated VLDL, cholesteryl esters are depleted while proteins are enriched. During the postprandial phase, the apolipoprotein (apo) profile of VLDL (d< 1.015 g/mL) is comparable in E2‐treated and control trout. Starvation of E2‐treated trout is accompanied by an enrichment in apo B240, A‐I and A‐II. The secretion levels of TG and VLDL‐TG, as determinedin vivo, by injecting Triton WR‐1339 to starving animals, are significantly higher in E2‐treated trout than in controls. In trout, as in chicks, E2 administration significantly increases the concentration and hepatic secretion of plasma VLDL independent of the nutritional status and the appearance of VTG in the plasma. This suggests the existence of similar mechanisms for the regulation of lipoprotein metabolism by estrogens in oviparous vertebrates.
A method for determination of the absolute stereochemistry of α,β‐epoxy alcohols derived from fatty acid hydroperoxides
Authors: Hamberg Mats 
Published: November 2006

AbstractA method for the determination of the absolute configuration of the alcohol group of fatty acid α,β‐epoxy alcohols was developed. The method consists of:(i) deoxygenation of the saturated epoxy alcohol to an allylic alcohol by treatment with triphenylphosphine selenide and trifluoroacetic acid; (ii) oxidative ozonolysis of the (−)‐menthoxycarbonyl derivative of the allylic alcohol; and (iii) steric analysis of the resulting 2‐hydroxy acid (methyl ester, (−)‐menthoxycarbonyl derivative) by gas‐liquid chromatography using appropriate reference compounds. The result obtained, coupled with knowledge of the relative configuration of the epoxy alcohol (erythro/threo) and of the geometrical configuration of the epoxide group (cis/trans), permitted assignment of the absolute configuration of all three asymmetric carbons of the α,β‐epoxy alcohol. The method was applied to the determination of the absolute stereochemistry of two hepoxilins recently isolated from the red algaMurrayella perilados.
Headspace gas chromatography to determine human low density lipoprotein oxidation
Authors: Frankel E. N. , German J. Bruce , Davis Paul A. 
Published: November 2006

AbstractWe previously described a rapid headspace gas chromatographic method for the determination of hexanal, an important decomposition product of n−6 polyunsaturated fatty acid (PUFA) peroxidation in rat liver samples and human red blood cell membranes. This method was applied to the measurement of Cu2+ catalyzed‐oxidation of freshly prepared human low density lipoproteins (LDL) from 10 healthy adult volunteers. A twofold variation in oxidative susceptibility was found by this assay for hexanal and other volatiles. Hexanal values correlated significantly (P<0.05) with total polyunsaturated fatty acid (PUFA), 18∶2 and n−6 PUFA contents of LDL; but poorly with 20∶4 and with vitamin E. Therefore, in addition to α‐tocopherol, other endogenous antioxidants and factors may contribute, to LDL's resistance to oxidation. This simple, rapid and sensitive method for oxidative susceptibility provides a useful component in the analysis of the prooxidant/antioxidant status of biological samples. The method is used routinely in our laboratories to determine specific peroxidation products of n−6 and n−3 PUFA.
Fluorescence assay of glucosylceramide glucosidase using NBD‐Cerebroside
Authors: Abe Akira , Shayman James A. , Radin Norman S. 
Published: November 2006

AbstractA sensitive fluorometric assay for glucocerebroside β‐glucosidase [Dinur, T., Grabowski, G.A., Desnick, R.J., and Gatt, S. (1984)Anal. Biochem. 136, 223–234] has been reexamined. It was found that the lipids containing the NBD moiety (12‐[N‐methyl‐N‐(7‐nitrobenz‐2‐oxa‐1,3‐diazol‐4‐yl)] used for standardization of the assay are light‐sensitive and that the yield of fluorescent light is very sensitive to the composition of the solvent used in the fluorometric measurement. Some protection against fading could be obtained by adding a free‐radical trapping agent, Slow Fade. The fading of the free NBD‐acid, when used for standardization, could be prevented by adding ethanol to the solvent, but this reduced the fluorescence yield. It is recommended that some of the fluorescent substrate be enzymatically hydrolyzed completely to NBD‐ceramide, which can be utilized as the standard without the need to add ethanol. A warning about enzyme reaction rate stability with time is given, with a suggestion for ensuring constancy of activity.
Heterogeneity of molecular weight and apolipoproteins in low density lipoproteins of healthy human males
Authors: Kahlon Talwinder S. , Shore Virgie G. , Lindgren Frank T. 
Published: November 2006

AbstractThe molecular weights of five low density lipoprotein (LDL) subfractions from four normal healthy males were determined by analytic ultracentrifuge sedimentation equilibria. Protein content of each subfraction was determined by elemental CHN analysis, and weights of apoprotein peptides were calculated. Molecular weights in subfractions of increasing density were 2.92±0.26, 2.94±0.12, 2.68±0.09, 2.68±0,28 and 2.23 ±0,22 million Da, and protein weight percentages were 21.05, 21.04, 22.05, 23.10 and 29.10, in subfractions, 1,2,3,4 and 5, respectively. Total mean apoprotein weights for respective subfractions were 614±53,621±45, 588±9,637±83 and 645 ±62 KDa. In addition to a single apoprotein B‐100 (apo B‐100) peptide with a mean carbohydrate content of 7.1% and a molecular weight of 550 KDa per LDL particle, there may be one or more apoprotein E peptides of 34 KDa and/or apoprotein C‐III of 9 KDa. In addition, subfractions 4 and 5 may contain 3–7% apolipoprotein (a). There is considerable heterogeneity among LDL subfractions as well as within the same fraction from different individuals. This heterogeneity may relate to differences in origin, metabolism and/or atherogenicity as a result of their content of apoproteins other than apo B‐100.
Effects of a platelet‐activating factor antagonist, CV‐6209, on Gastric mucosal lesions induced by ischemia‐reperfusion
Authors: Yoshikawa Toshikazu , Takahashi Shuji , Naito Yuji , Ueda Shigenobu , Tanigawa Toru , Yoshida Norimasa , Kondo Motoharu 
Published: November 2006

AbstractRecent research was shown that oxygen‐derived free radicals are involved in the pathogenesis of various diseases, including ischemia‐reperfusion injury. We have also reported that oxygen‐derived free radicals and lipid peroxidation may play an important role in gastric mucosal injury induced by ischemia‐reperfusion. The hypoxanthinexanthine oxidase system and neutrophils are considered important sources of oxygen‐derived free radicals in this process. In recent years, it also has been shown that serum platelet‐activating factor (PAF) levels increased during ischemia‐reperfusion, and that induction of superoxide generation by neutrophils is one of the important biological effects of PAF. In the present study, we examined the effect of CV‐6209, a specific PAF receptor antagonist, on gastric mucosal injury induced by ischemia‐reperfusion, to shed some light on the possible involvement of PAF in such lesions. CV‐6209 significantly attenuated the gastric mucosal injury induced by ischemia‐reperfusion, and inhibited both an increase of thiobarbituric acid reactive substances and a decrease of α‐tocopherol in gastric mucosa after ischemia‐reperfusion. However, CV‐6209 had no effect on gastric mucosal blood flow during ischemiano effect on gastric mucosal blood flow during ischemia‐reperfusion. These results suggest that endogenous PAF may play an important role in gastric mucosal injury induced by ischemia‐reperfusion, and that CV‐6209 exerts its beneficial effect mainly by inhibiting neutrophil superoxide production induced by PAF.
Absolute configuration of 12‐Oxo‐10,15(Z)‐phytodienoic acid
Authors: Hamberg Mats , Miersch Otto , Sembdner Gunther 
Published: November 2006

Abstract12‐Oxo‐10,15(Z)‐phytodienoic acid biosynthesized from 13(S)‐hydroperoxy‐9(Z),11(E),15(Z)‐octadecatrienoic acid using a preparation of corn (Zea mays L) hydroperoxide dehydrase recently was found to be a mixture of enantiomers in a ratio of 82∶18 (Hamberg, M., and Hughes, M.A. (1988)Lipids 23, 469–475). In this work, 12‐oxophytodienoic acid and (+)‐7‐iso‐jasmonic acid were converted into a common derivative, methyl 3‐hydroxy‐2‐pentyl‐cyclopentane‐1‐octanoate. From gas liquid chromatographic analysis of the (−)‐menthoxycarbonyl derivative of methyl 3‐hydroxy‐2‐pentyl‐cyclopentane‐1‐octanoates prepared from 12‐oxophytodienoic acid and (+)‐7‐iso‐jasmonic acid, it could be deduced that the major enantiomer of 12‐oxophytodienoic acid had the 9(S),13(S) configuration. Therefore, in the major enantiomer of 12‐oxophytodienoic acid, the configurations of the side chainbearing carbons are identical to the configurations of the corresponding carbons of (+)‐7‐iso‐jasmonic acid, thus giving support to previous studies indicating that 12‐oxophytodienoic acid serves as the precursor of (+)‐7‐iso‐jasmonic acid in plant tissue.
Geraniol interferes with membrane functions in strains ofCandida andSaccharomyces
Authors: Bard Martin , Albrecht Mark R. , Gupta Navyash , Guynn Cynthia J. , Stillwell William 
Published: November 2006

AbstractGeraniol, an olefinic terpene, was found to inhibit growth ofCandida albicans andSaccharomyces cerevisiae strains. Geraniol was shown to enhance the rate of potassium leakage out of whole cells and also was shown by fluorescence polarization to increaseC. albicans membrane fluidity. Biophysical studies using differential scanning calorimetry, fluorescence polarization and osmotic swelling of phospholipid vesicles demonstrated that geraniol decreased the phase‐transition temperature of dipalmitoylphosphatidylcholine vesicles, affected fluidity throughout the bilayer, particularly the central portion of the bilayers, and caused an increase in bilayer permeability to erythritol. Geraniol may have potential use as an antifungal agent.
Polyunsaturated fatty acids of serum lipids in myocardial infarction
Authors: Croffs John W. , Ogburn Paul L. , Johnson Susan B. , Holman Ralph T. 
Published: November 2006

AbstractTwo groups of volunteers had blood drawn for serum analysis of fatty acids. The first group was comprised of patients admitted to the hospital with possible myocardial infarction (MI). Blood was drawn at admission and at 12, 24 and 48 hr. These patients were subsequently divided into three groups, those with MI, those without (No MI) and those taking prostaglandin inhibitors (PGI), on the basis of the cardiac enzymes, electrocardiograms and clinical history. A fourth group of Normal nonstressed people was also drawn at 0, 12, 24 and 48 hr for comparison. Fatty acid composition of phospholipids (PL), nonesterified fatty acids (NEFA), triglycerides (TG) and cholesteryl esters (CE) was determined by capillary gas chromatography (GC), and comparison were made between the MI, No MI, PGI and Normal groups. Total NEFA were significantly elevated in patients admitted for possible MI compared with Normals. Those patients with MI had marginally higher levels of NEFA than the No MI group at each sampling time, but this difference was not statistically significant. The MI, No MI and PGI groups had significantly different fatty acid patterns in NEFA with reduced percentages of arachidonic acid (AA) than controls. The fatty acid patterns in the four lipid classes showed few significant differences comparing the MI, No MI and PGI groups. The regular use of prostaglandin inhibitors before hospitalization for chest pain was associated with a reduced frequency of MI (p<0.002). NEFA levels, nonesterified AA levels and fatty acid patterns in this group did not differ from those patients not taking prostaglandin inhibitors.
Microsomal desaturation‐elongation of linoleic acid following parenteral feeding with lipid emulsions in the rat
Authors: Innis Sheila M. , Yuen Doris E. 
Published: November 2006

AbstractThe effect of total parenteral nutrition (TPN) with lipid emulsion to supply either 27.5% or 2% total calories on in vitro desaturation‐elongation of 18∶2(n−6) by liver microsomes was studied in the rat. The emulsion lipid contained ca. 50% 18∶2(n−6) plus 8% 18∶3(n−3) or 77% 18∶2(n−6) plus 0.5% 18∶3(n−3). The reaction rate was influenced by the in vitro substrate concentration and inhibited above 50 μmol 18∶2(n−6)/mg microsomal protein. At maximum rates of desaturation‐elongation, the formation of triene and tetraene (n−6) fatty acids was reduced in rats given either of the two emulsions. The rate of (n−6) pentaene formation was increased in rats given the emulsion with low 18∶3(n−3) but not in rats given the emulsion with 8% 18∶3(n−3). Analyses of the microsomal lipid indicated increased free cholesterol in all rats that received TPN. Esterified cholesterol was increased only in rats given 27.5% TPN calories as lipid. Microsomal total phospholipids and phospholipid class distributions were not altered by TPN. The data are consistent with reports of reduced levels of long‐chain desaturation‐elongation metabolites of 18∶2(n−6) in tissue phospholipids following infusion of parenteral lipid. The data suggest that the mechanism may include alterations in other metabolic pathways such as cholesterol, in addition to desaturase enzyme activities, and may be influenced by both the quantity and fatty acid composition of the lipid infused.
Fenton reactions in lipid phases
Authors: Schaich K. M. , Borg D. C. 
Published: November 2006

AbstractMetal catalysis of membrane lipid oxidation has been thought to occur only at cell surfaces. However, conflicting observations of the pro‐oxidant activity of ferric (Fe3+) vs ferrous (Fe2+) forms of various chelates have raised questions regarding this dogma. This paper suggests that the solubilities of iron complexes in lipid phases and the corresponding abilities to initiate lipid oxidation there, either directly or via Fenton‐like production of reactive hydroxyl radicals, are critical determinants of initial catalytic effectiveness.Partitioning of Fe3+ and Fe2+ complexes and chelates into bulk phases of purified lipids was quantified by atomic absorption spectroscopy. mM solutions of iron salts partitioned into oleic acid at levels of about micromolar. Ethylenediamine tetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) chelates were somewhat less soluble, while adenosine diphosphate (ADP) chelates, and ferrioxamine were soluble as chelates at greater than 10−5 M. Solubilities of all iron compounds in methyl linoleate were 10‐ to 100‐fold lower.To determine whether Fenton‐like reactions occur in lipid phases, H2O2 and either Fe2+ or Fe3+ and a reducing agent were partitioned into the lipid along with the spintrap 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO), and free radical adducts were recorded by electron paramagnetic resonance (EPR). Hydroxyl radicals (OH.) adducts were observed in oleic acid, but in lipid esters secondary peroxyl radicals predominated, and the presence of OH. adducts was uncertain.
Ascorbate‐enhanced lipid peroxidation in photooxidized cell membranes: Cholesterol product analysis as a probe of reaction mechanism
Authors: Bachowski Gary J. , Thomas James P. , Girotti Albert W. 
Published: November 2006

AbstractCholesterol was used as an in situ probe for studying mechanisms of lipid peroxidation in isolated erythrocyte membranes subjected to different prooxidant conditions. The membranes were labeled with [14C]cholesterol by exchange with prelabeled unilamellar liposomes and photosensitized with hematoporphyrin derivative. Irradiation with a dose of blue light resulted in thiobarbituric acid‐detectable lipid peroxidation that was increased markedly by subsequent dark incubation with 0.5–1.0 mM ascorbate (AH−). Ascorbate‐stimulated lipid peroxidation was inhibited by EDTA, desferrioxamine (DOX) and butylated hydroxytoluene (BHT), suggesting that the process is free radical in nature and catalyzed by membrane‐bound iron. Thin layer chromatography and radiometric scanning of extracted lipids from photooxidized membranes revealed that the major oxidation product of cholesterol was the 5α‐hydroperoxide (5α‐OOH), a singlet oxygen adduct. Post‐irradiation treatment with AH−/Fe(III) resulted in an almost‐total disappearance of 5α‐OOH and the preponderance of free radical oxidation products, e.g. 7‐ketocholesterol, the epimeric 7α‐/7β‐hydroperoxides (7α‐/7β‐OOH) and their respective alcohols (7α‐/7β‐OH). EDTA, DOX and BHT inhibited the formation of these products, while catalase and superoxide dismutase had no effect. These results are consistent with a mechanism involving 1‐electron reduction of photogenerated hydroperoxides to oxyl radical, which trigger bursts of free radical lipid peroxidation. Though generated in this system, partially reduced oxygen species, viz. superoxide, hydrogen peroxide and hydroxyl radical, appear to be relatively unimportant in the autoxidation process.