bluuebunny/crossref_metadata_2025_split huggingface dataset:
Time course of dolichol and dolichyl phosphate in regenerating rat liver
Authors: Yamada Kouji , Murakami Manabu , Katayama Kouichi , Sato Tadashi 
Published: November 2006

AbstractBy using novel high performance liquid chromatographic methods, the time course of dolichol and dolichyl phosphate in regenerating rat liver was investigated and compared with that for cholesterol. The cholesterol level in the liver increased more rapidly than the level of dolichyl phosphate (Dol‐P). HMG‐CoA reductase activity correlated well with cholesterol concentration. The level of Dol‐P at day 1 was lower than that in normal liver, but was increased at three to five days after hepatectomy, which correlates well with mannosyl transferase activity. Dolichol decreased for three days, and thereafter increased until 11 days after hepatectomy. The compositions of dolichol and Dol‐P homologues did not change during the experimental period. The results indicate that the cholesterol content in regenerating rat liver increased first, followed by Dol‐P, and finally dolichol.
Free fatty acid inhibition of the insulin induction of glucose‐6‐phosphate dehydrogenase in rat hepatocyte monolayers
Authors: Salati Lisa M. , Adkins‐Finke Bonnie , Clarke Steven D. 
Published: November 2006

AbstractRat hepatocytes in monolayer culture were utilized to determine if the decrease in glucose‐6‐phosphate dehydrogenase (G6PD) activity resulting from the ingestion of fat can be mimicked by the addition of fatty acids to a chemically, hormonally defined medium. G6PD activity in cultured hepatocytes was induced several‐fold by insulin. Dexamethasone or T3 did not amplify the insulin induction of G6PD. Glucose alone increased G6PD activity in cultured hepatocytes from fasted donors by nearly 500%. Insulin in combination with glucose induced G6PD an additional two‐fold. The increase in G6PD activity caused by glucose was greater in hepatocytes isolated from 72 hr‐fasted rats as compared to fed donor rats. Such a response was reminiscent of the “overshoot” phenomenon in which G6PD activity is induced well above the normal level by fasting‐refeeding rats a high glucose diet. Addition of linoleate to the medium resulted in a significant suppression of insulin’s ability to induce G6PD, but linoleate had no effect on the induction of G6PD activity by glucose alone. A shift to the right in the insulin‐response curve for the induction of G6PD also was detected for the induction of malic enzyme and acetyl‐CoA carboxylase. Arachidonate (0.25 mM) was a significantly more effective inhibitor of the insulin action than linoleate was. Apparently rat hepatocytes in monolayer culture can be utilized as a model to investigate the molecular mechanism by which fatty acids inhibit the production of lipogenic enzymes. In part, this mechanism of fatty acid inhibition involves desensitization of hepatocytes to the lipogenic action of insulin.
Metabolism of sitosteryl β‐D‐glucoside and its nutritional effects in rats
Authors: Weber Nikolaus 
Published: November 2006

Abstract[4‐14C]Sitosteryl β‐D‐glucoside, intragastrically administered to rats, was not absorbed by the intestinal mucosa. At three hr after the application, radioactivity was concentrated almost exclusively in the digesta of stomach, small intestine as well as cecum and colon, whereas only low proportions of radioactively labeled compounds were found in the various tissues of the gastrointestinal tract. Minor proportions of labeled metabolites of [4‐14C]sitosteryl β‐D‐glucoside, such as sitosterol and sitosteryl esters, were formed in the small intestine in vivo and in slices of small intestine in vitro. In the tissues of cecum and colon as well as the digesta derived from them, high proportions of labeled coprositostanol, i.e. 24α‐ethyl‐5β‐cholestan‐3β‐ol, that obviously had been formed by bacterial degradation of the substrate were detected.The feeding of sitosteryl β‐D‐glucoside (0.5 g/kg body weight×day) over a period of four weeks did not alter significantly body weights or organ weights of rats. Analyses of steryl lipids of the various organs and tissues confirmed the findings obtained with the radioactive substrate: neither sitosteryl β‐D‐glucoside nor sitosterol or sitosteryl esters derived therefrom had been transported in appreciable amounts to organs and tissues outside the alimentary canal during the feeding period. Minor proportions of unmetabolized sitosteryl β‐D‐glucoside were detected in the tissues of stomach and intestine, whereas large proportions of the substrate were found in feces of rats that had received the sitosteryl β‐D‐glucoside‐containing diet; coprositostanol was found in feces of these animals in high proportions as well. Thus, the use of sitosteryl β‐D‐glucoside as emulsifier or preservative in food and feed does not appear to involve any risk.
Regulation of squalene epoxidase activity by membrane fatty acid composition in yeast
Authors: Buttke T. M. , Brint S. L. , Lowe M. R. 
Published: November 2006

AbstractDeprivingSaccharomyces cerevisiae strain GL7 of exogenous unsaturated fatty acid supplements causes this sterol biosynthetic mutant to accumulate squalene at the expense of squalene epoxide and squalene diepoxide. To further characterize the apparent relationship between squalene epoxidase activity and membrane fatty acid composition, a variety of unsaturated fatty acids differing in their chain lengths and in the positions and orientation (cis ortrans) of their double bonds were tested for their ability to promote turnover of endogenous squalene in cells previously deprived of olefinic supplements. All of the unsaturated fatty acids tested were found to restore squalene epoxidase activity but there were marked differences in their efficacies that best were correlated with the extent to which they reduced the medium chain (C‐10+C‐12) saturated fatty acid content of cellular phospholipids. Additional studies demonstrated that de novo protein synthesis was required for the restoration of squalene epoxidase activity in unsaturated fatty aciddeprived cells.
Effects of cholestanol feeding and cholestyramine treatment on the tissue sterols in the rabbit
Authors: Buchmann Marie S. , Clausen Ole P. 
Published: November 2006

AbstractRabbits were fed diets enriched with cholestanol or cholestereol (3.5 g/wk) for 4–12 weeks. During cholestanol feeding, the concentration of cholestanol in blood serum, liver, heart and aorta increased 15–30 times. In serum and liver, the concentration of cholesterol also increased. Cholestanol‐fed rabbits developed inflammatory changes in the liver, with proliferation of small bile ducts. Liver tests were only slightly abnormal. Morphological atherosclerosis of the aorta was only occasionally seen in rabbits receiving cholestanol for eight weeks or less.During cholesterol feeding, the amounts of cholesterol in different tissues increased dramatically, most in the aorta. Morphological atherosclerosis in the aorta was found in all rabbits fed cholesterol‐enriched diets for more than four weeks. Brain cholestanol was doubled in rabbits fed cholestanol for eight weeks, whereas brain sterols did not change significantly during cholesterol feeding. After an additional regression period with cholestyramine for eight weeks, the increased content of cholestanol in the brain was unchanged in cholestanol‐fed rabbits. These observations are discussed in relation to the cholestanolosis of the brain that develops in the rare inherited human disease cerebrotendinous xanthomatosis.
Dominance of Δ7‐sterols in the family caryophyllaceaein the family caryophyllaceae
Authors: Salt Thomas A. , Adler John H. 
Published: November 2006

AbstractThe predominant 4‐desmethylsterols from the leaves of 12 species in 11 genera of the family Caryophyllaceae are 24‐ethyl‐Δ7‐sterols. In eight species,Scleranthus annus L.,Paronychia virginica Spreng.,Lychnis alba Mill.,Silene cucubalus Wibel,Dianthus armeria L.,Gypsophilia paniculata L.,Saponaria officinales L. andMyosoton aquaticum (L.) Moench, the major sterols are spinasterol (24α‐ethylcholesta‐7,22E‐dien‐3β‐ol) and 22‐dihydrospinasterol (24α‐ethylcholest‐7‐en‐3β‐ol), with spinasterol at more than 60% of the desmethylsterol in the latter six species. Both 24α‐and 24β‐ethyl‐Δ7‐sterols are present in two species,Minuartia caroliniana Walt. andSpergula arvensis L., which possess 24β‐ethylcholesta‐7,25(27)‐dien‐3β‐ol and 24β‐ethylcholesta‐7,22E,25(27)‐trien‐3β‐ol as well as spinasterol and 22‐dihydrospinasterol.Cerastium arvense L.,C. vulgatum L. andArenaria serpyllifolia L. possess 24‐alkyl‐Δ5 and Δ7‐sterols. These three species synthesize sitosterol (24α‐ethylcholest‐5‐en‐3β‐ol), 24ζ‐methylcholest‐5‐en‐3β‐ol, spinasterol, 22‐dihydrospinasterol and the stanols, sitostanol (24α‐ethyl‐5α‐cholestan‐3β‐ol) and 24ζ‐methyl‐5α‐cholestan‐3β‐ol. Avenasterol (24‐ethylcholesta‐7,24(28)Z‐dien‐3β‐ol) was also isolated from five species. Sterol biosynthetic capability may be a useful characteristic in examining the taxonomic relatedness of plants in the Caryophyllaceae.
Spectroscopic investigations of the water pool in lecithin reverse micelles
Authors: Kumar V. V. , Raghunathan P. 
Published: November 2006

AbstractThe nature of the water pool formed in the reverse micellar system, lecithin/nonpolar solvent/water, has been investigated by means of near infrared, ultraviolet, fluorescence emission and visible spectroscopic techniques. The three nonpolar solvents chosen in this study were benzene, carbon tetrachloride and cyclohexane. Near infrared spectroscopic studies revealed that the amount of water present in the bulk organic phase is negligible at all water concentrations studied in all three solvents. The results of the polarity probe and 8‐anilinonaphthalene sulfonic acid (ANSA) fluorescence emission maxima studies indicate that the polarity of the water pool is much lower than that of bulk water. The difference in polarity between the water pool and bulk water decreases with increasing water concentration in benzene and carbon tetrachloride systems. However, in the cyclohexane system, at a water content of 6 moles of water per mole of lecithin, where the system is known to change from isotropic reverse micelle to anisotropic liquid crystalline state, the polarity of the water pool is found to decrease.
Specific induction of lauric acid ω‐hydroxylase by clofibrate, diethylhexyl‐phthalate and 2,4‐dichlorophenoxyacetic acid in higher plants
Authors: Salaün Jean‐Pierre , Simon Annick , Durst Francis 
Published: November 2006

AbstractRecently, we have found in plant microsomes two laurate hydroxylases that catalyze the terminal hydroxylation or the in‐chain hydroxylation of the fatty acid. These two hydroxylases, which are both cytochrome P‐450 enzymes, are never found in the same plant. This study shows that the hypolipidemic drug clofibrate induces the lauric acid ω‐hydroxylase activity inVicia and soybean seedlings. The marked increase in activity (>20‐fold) produced by clofibrate was dose‐dependent but was not paralleled by an enhancement of bulk cytochrome P‐450 or cinnamic acid 4‐hydroxylase. Compounds related to clofibrate by structure (2,4‐dichlorophenoxyacetic acid) or effects (diethylhexyl‐phthalate) also stimulated the ω‐hydroxylating system in these plants. In contrast, the lauric acid in‐chain hydroxylase from Jerusalem artichoke tubers was induced less than cinnamic acid 4‐hydroxylase activity and bulk cytochrome P‐450 in tissues incubated in clofibrate solution. This suggests that clofibrate induces preferentially the laurate ω‐hydroxylating isozyme in plants.
A phospholipase C with a high specificity for platelet‐activating factor in rabbit liver light mitochondria
Authors: Nishihira Jun , Ishibashi Teruo 
Published: November 2006

AbstractThe light mitochondrial fraction from rabbit liver was found to catalyze the hydrolysis of platelet‐activating factor (PAF, 1‐O‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine) by the phospholipase C reaction to form 1‐O‐alkyl‐2‐acetyl‐glycerol and phosphocholine. The highest specific phospholipase C activity occurred in the liver and kidney. A subcellular survey showed that the enzyme was of lysosomal origin. The enzyme was solubilized with 2% Triton X‐100 from rabbit liver light mitochondria and purified ca. 600‐ to 700‐fold with a 17% yield using procedures that included hydroxyapatite, Sepharose 4B and isoelectric focusing column chromatography followed by fast protein liquid chromatography. The enzyme consists of two forms having a pl of 4.7 and 5.8. Each form was purified to a homogeneous state as judged by sodium dodecyl sulfate‐polyacrylamide disc gel electrophoresis. The enzyme migrated to positions corresponding to apparent molecular weights of 33,000 and 75,000, respectively. The purified enzymes of pl 4.7 and 5.8 had pH optima of 8.2 and 8.5 and apparent Km values of 55.6 and 45.5 μM for PAF, respectively. Furthermore, their phospholipase C activity was significantly inhibited by the addition of 1 mM EDTA. EDTA‐inactivated enzyme, however, recovered completely upon addition of Ca2+ to the original level. p‐Chloromercuribenzoate markedly inhibited enzyme activity, suggesting that phospholipase C is a—SH enzyme. The physiological role of the enzyme should be evaluated, considering its specificity for a highly potent, biologically active ether‐phospholipid.
Influence of dietary vitamin E, selenium and age on regional distribution of α‐tocopherol in the rat brain
Authors: Meydani Mohsen , Macauley John B. , Blumberg Jeffrey B. 
Published: November 2006

AbstractConcentrations of α‐tocopherol (α‐T) in plasma, cerebrum, cerebellum, midbrain and brain stem and activity of selenium (Se)‐dependent glutathione peroxidase (GSH‐Px) in plasma were measured in 1‐ and 15‐month‐old male F344 rats fed diets containing vitamin E (E, IU/kg) and Se (ppm) in the following combinations: 30 E, 0.1 Se (control diet, minimum requirements); 200E, 0.2 Se; 0.0 E, 0.2 Se; 200 E, 0.0 Se; 0.0 E, 0.0 Se for 8 or 20 weeks. α‐T and GSH‐Px levels in plasma were reflective of dietary treatment in young rats in which an interaction of the two nutrients was noted. A longer period of dietary vitamin E deficiency was necessary to deplete plasma α‐T and depress GSP‐Px activity significantly in the old rats. Among the brain regions of all ages, cerebrum and midbrain had the highest concentrations of α‐T while cerebellum showed the lowest. However, cerebellum of young rats and cerebellum and brain stem of old rats had a greater α‐T accumulation with doubly supplemented diets, whereas only cerebellum of young and old rats showed a marked increased of α‐T with vitamin E supplementation. In old rats, vitamin E deficiency resulted in greater depletion of α‐T in cerebellum and brain stem than cerebrum and midbrain regions. Se deficiency in brain stem of young and old rats significantly decreased α‐T accumulation by vitamin E supplementation. Se supplementation marginally alleviates vitamin E depletion in brain. Cerebellum and brain stem of old rats fed the minimum requirements of vitamin E and Se for 20 weeks showed a significant decline in α‐T. Therefore, cerebellum and brain stem appear, to have a higher turnover of α‐T than cerebrum and midbrain, and older rats may require a higher level, of vitamin E in the diet to maintain steady state levels of α‐T in these regions.
A highly active soluble diacylglycerol synthesizing system from developing rapeseed,Brassica napusL.
Authors: Murphy Denis J. 
Published: November 2006

AbstractThe subcellular distribution of the enzymes of triacylglycerol biosynthesis has been studied in developing oilseed rape. All in vitro enzymatic activities from oleoyl‐CoA to triacylglycerol were sufficient to account for the known rate of oleate deposition in triacylglycerol in vivo. The enzymatic activities from oleoyl‐CoA to diacylglycerol preferentially were localized in a 150,000 g supernatant fraction, while the diacylglycerol acyl‐transferase mostly was associated with the microsomal (20,000 g pellet and 150,000 g pellet) and oil‐body fractions. The soluble (150,000 g supernantant) fraction rapidly incorporated oleate from [1‐14C]oleoyl‐CoA into diacylglycerol with rates of 40 nm min−1g−1FW at 20 μM oleoyl‐CoA. The pH optimum was 7.5–9.0, and normal saturation kinetics were seen with oleoyl‐CoA; the S0.5was about 32 μM. Exogenous acyl acceptors, such as glycerol 3‐phosphate, lysophosphatidic acid and lysophosphatidylcholine stimulated oleate incorporation into diacylglycerol. The detergents Triton X‐100 and sodium cholate inhibited diacylglycerol formation at concentrations in the region of their critical micellar concentration, while n‐octyl‐β,D‐glyco‐pyranoside had no effect, even at high concentration. The significance of these findings for the mechanism of oil‐body formation in developing oilseeds is discussed.
Linoleic acid requirement of rats fedtrans fatty acids
Authors: Zevenbergen J. L. , Houtsmuller U. M. T. , Gottenbos J. J. 
Published: November 2006

AbstractThe amount of linoleic acid required to prevent undesirable effects of C18trans fatty acids was investigated. In a first experiment, six groups of rats were fed diets with a high content oftrans fatty acids (20% of energy [en%]), and increasing amounts of linoleic acid (0.4 to 7.1 en%). In a second experiment, four groups of rats were fed diets designed to comparetrans fatty acids with saturated andcis‐monounsaturated fatty acids of the same chain length at the 2 en% linoleic acid level. After 9–14 weeks, the oxygen uptake, lipid composition and ATP synthesis of heart and liver mitochondria were determined.The phospholipid composition of the mitochondria did not change, but the fatty acid compositions of the two main mitochondrial phospholipids were influenced by the dietary fats.Trans fatty acids were incorporated in all phospholipids investigated. The linoleic acid level in the phospholipids, irrespective of the dietary content of linoleic acid, increased on incorporation oftrans fatty acids. The arachidonic acid level had decreased in most phospholipids in animals fed diets containing 2 en% linoleic acid. At higher linoleic acid intakes, the effect oftrans fatty acids on the phospholipid arachidonic acid level diminished. However, in heart mitochondrial phosphatidylethanolamine,trans fatty acids significantly increased the arachidonic acid level. Despite these changes in composition, neither the amount of dietary linoleic acid nor the addition oftrans fatty acids influenced the mitochondrial function. For rats, a level of 2 en% of linoleic acid is sufficient to prevent undesirable effects of high amounts of dietary C18trans fatty acids on the mitochondrial function.
Human placenta gangliosides
Authors: Taki Takao , Matsuo Ken‐ichi , Yamamoto Kaname , Matsubara Toshiko , Hayashi Akira , Abe Tadayuki , Matsumoto Makoto 
Published: November 2006

AbstractGangliosides extracted from human placenta were composed of four major components (G1–G4), which were purified by silica beads column chromatography. The structures of these gangliosides were analyzed by exoglycosidase treatments, 400 MHz proton magnetic resonance spectroscopy and gas chromatography‐mass spectrometry and were concluded to be as follows:
image Gangliosides containing more than 10 sugar residues were observed in addition to the above four major components. But ganglio‐series gngliosides were undetectable in the placenta.
Butter‐enriched diets reduce arterial prostacyclin production in rats
Authors: O'Dea Kerin , Steel Merryn , Naughton Joan , Sinclair Andrew , Hopkins Grant , Angus James , He Guo‐Wei , Niall Margaret , Martin T. J. 
Published: November 2006

AbstractRats were fed diets containing 10%, 30% or 50% energy as fat derived predominantly from butter or lard. The protein content of the diets was maintained at 20%. After three weeks on the diets, the rats were killed and the following parameters measured: prostacyclin production in vitro from abdominal aorta and mesenteric artery; platelet aggregation to ADP and thrombin; fatty acid composition of the phospholipids in plasma, thoracic aorta and liver; smooth muscle reactivity and release of endothelial derived relaxing factor (EDRF) from aortic endothelium stimulated by acetylcholine. There was no significant effect of increasing fat content of the diets (neither lard nor butter) on platelet aggregation. In contrast, prostacyclin production in both the mesenteric artery and the abdominal aorta fell in a concentration‐dependent manner in the butter‐supplemented rats. However, no effect on prostacyclin production was detected in arteries from the lard‐supplemented animals. The effects of the diets on prostacyclin (PGI2) production correlated very well with the changes in plasma, aortic and liver phospholipid arachidonic acid (AA) and eicosapentaenoic acid (EPA) contents. AA decreased in a concentration‐dependent manner in the rats fed the butter‐enriched diets but did not change in those fed the lard‐enriched diets, whereas EPA rose in a concentration‐dependent manner in the butter‐fed rats and was unchanged in the lard‐fed animals. The clear‐cut effects of the butter‐enriched diets on aortic phospholipid fatty acid composition and aortic PGI2 production were accompanied by a significant reduction in smooth muscle relaxation to EDRF. These results indicate that in the rat, enrichment of the diet with butter can reduce the concentration of AA and increase that of EPA in plasma and tissue phospholipids with a parallel reduction in arterial PGI2 production and EDRF.
Effects of cyclopropenoid fatty acids on fungal growth and lipid composition
Authors: Schmid Katherine M. , Patterson Glenn W. 
Published: November 2006

AbstractCyclopropenoid fatty acids (CPE) isolated fromSterculia foetida oil by urea clathration and reverse phase high performance liquid chromatography (HPLC) were introduced into fungal cultures. Stearate levels in phospholipids and triacylglycerols fromUstilago maydis sporidia rose considerably in response to 30 μM CPE. In addition, CPE themselves were incorporated into glycerolipid fractions. Sterol composition was unaffected. Changes in lipid composition were accompanied by inhibition of dry weight accumulation and sporidial number. Treated sporidia showed irregular wall deposition and a branched morphology. Oleate alleviated CPE effects on growth and morphology. Hyphal extension byRhizoctonia solani was inhibited somewhat by 30 μM sterculate, whileFusarium oxysporum showed no appreciable response. Although CPE appeared to inhibit fatty acid desaturation byF. oxysporum, gross increases in the proportion of stearate were limited to the triacylglycerol fraction during 30 μM treatments. The possibility that the CPE synthesized by plants serve as antifungal agents is discussed.
Long‐chain alkanediols: Biological markers for cyanobacterial contributions to sediments
Authors: Morris R. J. , Brassell S. C. 
Published: November 2006

AbstractOne significant family of sedimentary lipids of widespread occurrence are series of C28–C32 alkanediols and hydroxyketones. The recognition of the same series of alkanediols as major lipid components of a field population of the cyanobacteriumAphanizomenon flos‐aquae leads us to propose that these lipids are markers for cyanobacterial inputs to sediments. The frequency of occurrence of the alkanediols in sedimentary environments supports the recent finding that cyanobacteria are major contributors to the aquatic biomass.