bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantitation of vitamin K in human milk
Authors: Canfield Louise M. , Hopkinson Judy M. , Lima Anne F. , Martin Gail S. , Sugimoto Kyoto , Burr Jeanne , Clark Larry , McGee Daniel L. 
Published: November 2006

AbstractA quantitative method was developed for the assay of vitamin K in human colostrum and milk. The procedure combines preparative and analytical chromatography on silica gel in a nitrogen atmosphere followed by reversed phase high performance liquid chromatography (HPLC). Two HPLC steps were used: gradient separation with ultraviolet (UV) detection followed by isocratic separation detected electrochemically. Due to co‐migrating impurities, UV detection alone is insufficient for identification of vitamin K. Exogenous vitamin K was shown to equilibrate with endogenous vitamin K in the samples. A statistical method was incorporated to control for experimental variability. Vitamin K1 was analyzed in 16 pooled milk samples from 7 donors and in individual samples from 15 donors at 1 month post‐partrum. Vitamin K1 was present at 2.94±1.94 and 3.15±2.87 ng/mL in pools and in individuals, respectively. Menaquinones, the bacterial form of the vitamin, were not detected. The significance of experimental variation to studies of vitamin K in individuals is discussed.
A simple device for the optimized isolation of fat cells
Authors: Meignen J. M. , Desnuelle C. , Boyer J. 
Published: November 2006

AbstractWe describe a simple cell isolation device that allows the separation and sequential collection of fat cells as they are released from adipose tissue fragments exposed to a collagenase preparation. This is done without interrupting the digestion process. Use of the device allows for appreciable lowering of the degree of cell damage and the extent to which larger cells are ruptured during the isolation process. Fat cells isolated by this technique elicit a higher level of metabolic activity as reflected by their improved response to the lipolytic action of epinephrine.
Lipids in gap junction assembly and function
Authors: Malewicz Barbara , Kumar V. V. , Johnson Ross G. , Baumann Wolfgang J. 
Published: November 2006

AbstractGap junctions (GJ) are important regulators of cellular function. They provide channels for the direct movement of small molecules between cells and thus control cell‐to‐cell transfer of metabolites and the transmission of various stimuli. Gap junctions have been shown to be involved in a multitude of cellular processes ranging from cell synchronization and neuronal function to cell differentiation and carcinogenesis. Much knowledge has been gained in recent years concerning the structure and molecular organization of GJ proteins; yet, the mechanisms that control and modulate gap junction assembly and function are still not well understood. Although it is quite apparent that the GJ proteins assemble in the lipid milieu of the plasma membrane, and that the cluster of proteins assembled in the junction do function in a lipid environment, there is a general paucity of information on the role of lipids in the gap junction assembly process and in the function of gap junctions.The present review is a comprehensive account of current knowledge on gap junction lipids. We also discuss what is known to date on the involvement of lipids in gap junction formation. Special emphasis is being placed on the potential role of membrane cholesterol in gap junction assembly and function.
Effect of temperature on the incorporation into phospholipid classes and metabolismvia desaturation and elongation of n−3 and n−6 polyunsaturated fatty acids in fish cells in culture
Authors: Tocher Douglas R. , Sargent John R. 
Published: November 2006

AbstractThe incorporation of 18∶2n−6, 18∶3n−3, 20∶4n−6 and 20∶5n−3 was greater at 10°C than at 22°C in Atlantic salmon (AS), rainbow trout (RTG‐2) and turbot (TF) cells. However, there were generally no significant differences between the amount of incorporation of all four polyunsaturated fatty acids (PUFA) into total lipid within a cell type at either 22°C or 10°C. The distributions of the PUFA between individual phospholipid classes at 22°C was essentially the same in AS and TF cells—with the C18 PUFA the order of incorporation in these cells was phosphatidylcholine (PC) > phosphatidylethanolamine (PE) > phosphatidic acid/cardiolipin (PA/CL); with 20∶4n−6 the order was PE and phosphatidylinositol (PI)>PC; with 20∶5n−3, PE>PC. In RTG‐2 cells at 22°C the distributions of the C18 PUFA were similar to the other cell lines, but with 20∶4n−6 the order was PC>PI>PE, and with 20∶5n−3 it was PC>PE. At 10°C the incorporation of C18 PUFA into PC increased and into PE and PA/CL decreased, in general, in all cell lines. Incorporation of 20∶5n−3 into PC and PE was increased and decreased at 10°C, respectively, in AS and TF cells, whereas in RTG‐2 cells the changes at 10°C were opposite i.e., increased in PE and decreased in PC. With 20∶4n−6, incorporation into PC at 10°C was increased in all cell lines with decreased incorporation into PI in AS and RTG‐2 cells and into PE in AS and TF cells, whereas incorporation of 20∶4n−6 into PE increased in RTG‐2 cells. The metabolismvia desaturation and elongation of the n−3 PUFA was greater than that of the equivalent n−6 PUFA in all cell lines, irrespective of temperature. There was less conversion of the C18 PUFA at 10°C than at 22°C in RTG‐2 and TF cells, but the conversion of 18∶3n−3 by AS cells was increased at 10°C. Temperature had no effect on the conversion of the C20 PUFA.
Phospholipid and fatty acid composition of frog (Rana esculenta) liver—a circannual study
Authors: Scapin S. , Baldini P. , Luly P. 
Published: November 2006

AbstractLiver lipid composition of the frogRana esculenta was examined on a circannual basis. In particular, phospholipid and cholesterol content, relative phospholipid distribution, and fatty acid patterns have been studied. Seasonal acclimatization is associated with significant modifications of phospholipid content and of the relative proportion of phospholipid classes, while cholesterol level is unchanged throughout the year. In regard to the fatty acid composition of total phospholipids as well as of the four major phospholipid classes—phosphatidylcholine (PC); phosphatidylethanolamine (PE); sphingomyelin (SM); phosphatidylserine (PS)—it appears that the liver of “summer animals” is characterized by a higher unsaturation index due to a decrease of saturated fatty acids and to an increased content of n−3 and n−6 polyunsaturated fatty acids. The results suggest that relevant compositional changes occur mainly in spring and autumn: these changes could be interpreted as being the result of both a nutritionally‐ and thermally‐induced seasonal adaptation directed toward the preservation of membrane‐associated physiological activities that are linked to the transition from the active to the inactive state of the animal.
The association of lysophosphatidylcholine with isolated cardiac myocytes
Authors: Man Ricky Y. K. , Kinnaird Anne A. A. , Bihler Ivan , Choy Patrick C. 
Published: November 2006

AbstractThe ability of exogenous lysophosphatidylcholine to produce electrophysiological derangements and cardiac arrhythmias in the heart has been documented. The action of lysophosphatidylcholine is thought to be mediated via its association with the membrane. The present study examined the nature of the association of lysophosphatidylcholine with isolated rat myocyte membrane. The association was studied by incubating myocytes in a lysophosphatidylcholine‐containing medium. The association of lysophosphatidylcholine with the myocyte sarcolemma was not affected by palmitic acid and glycerophosphocholine but was reduced by platelet‐activating factor (PAF). The addition of albumin (5 mg/mL) at the end of the incubation period effectively removed the lysophosphatidylcholine from the myocytes. Our results suggest that most of the lysophosphatidylcholine in isolated myocytes was associated preferentially with the outer leaflet of the myocyte sarcolemma. This type of association might be responsible for the lysophosphatidylcholine‐induced electrophysiological alterations in the heart.
Influence of dietary linoleic acid andtrans fatty acids on the fatty acid profile of cardiolipins in rats
Authors: Høy Carl‐Erik , Hølmer Gunhild 
Published: November 2006

AbstractCardiolipins (CL) have unique fatty acid profiles with generally high levels of polyunsaturated fatty acids, primarily 18∶2n−6, and low levels of saturated fatty acids. In order to study the effect of dietary fatty acid isomers on the fatty acid composition of cardiolipins, rats were fed partially hydrogenated marine oils (HMO), rich in 16∶1, 18∶1, 20∶1, and 22∶1 isomeric fatty acids, supplemented with linoleic acid at levels ranging from 1.9% to 14.5% of total fat. Although the dietary fats contained 33%trans fatty acids, the levels oftrans fatty acids in CL were below 2.5% in all organs. The fatty acid profiles of cardiolipins of liver, heart, kidney and testes showed different responses to dietary linoleic acid level. In liver, the contents of 18∶2 reflected the dietary levels. In heart and kidney, the levels of 18∶2 also parallelled increasing dietary levels, but in all groups fed HMO, levels of 18∶2 were considerably higher than in the reference group fed palm oil. In testes, the 18∶2 levels were unaffected by the dietary level of 18∶2 and HMO.
Phospholipid fatty acid composition of various mouse tissues after feeding α‐linolenate (18∶3n−3) or eicosatrienoate (20∶3n−3)
Authors: Berger Alvin , German J. Bruce 
Published: November 2006

AbstractThe selective incorporation of dietary α‐linolenate (18∶3n−3) and its elongation product, eicosatrienoate (20∶3n−3), into various phospholipids (PL) of mouse liver, spleen, kidney, and heart, was examined in a two‐week feeding trial by assessing mol % changes in associated fatty acids. Mice were fed fat‐free AIN 76A diets modified with either 2 wt% safflower oil (control); 1% safflower and 1% linolenate; or 1% safflower and 1% eicosatrienoate. After linolenate or eicosatrienoate feeding, 20∶4n−6 was reduced by 36–50% in liver phosphatidylcholine (PC) and in liver and spleen phosphatidylethanolamine (PE). Linolenate was minimally incorporated into PL, but was desaturated and elongated to 20∶5n−3, 22∶5n−3, and 22∶6n−3, with notable differences in the quantity of these n−3 derivatives associated with different tissues and PL. Eicosatrientoate was uniquely incorporated into the cardiolipin (CL) pool of all organs. There was also considerable retroconversion of 20∶3n−3 to 18∶3n−3 (PC, PE). Dietary eicosatrienoate may therefore affect metabolism in diverse ways—20∶3n−3, which is retroconverted to 18∶3n−3, may provide substrate for 20∶5n−3 and 22∶6n−3 syntheses, whereas intact 20∶3n−3 may be incorporated into the CL pool. Acyl modifications of CL are known to affect the activity of key innermitochondrial enzymes, such as cytochrome c oxidase.
Synthesis and characterization of cytochrome P‐450 epoxygenase metabolites of eicosapentaenoic acid
Authors: VanRollins Mike 
Published: November 2006

AbstractEicosapentaenoic acid, a major component of fish oil extracts, was recently shown to be metabolized to vicinal diol regioisomers by renal and hepatic cytochrome P‐450 epoxygenases. The diol products were also found in the urine of people ingesting fish oil. In the present report, we developed a chemical method of making milligram amounts of the epoxide intermediates and their diol products. Eicosapentaenoic acid was reacted with 0.1 eq.m‐chloroperoxybenzoic acid for 15 min. After normal‐ and reverse‐phase high performance liquid chromatography plus capillary gas chromatography and electron impact mass spectrometry, the products were identified as 17,18‐cis‐epoxyeicosa‐5,8,11,14‐tetraenoic, 14,15‐cis‐epoxy‐eicosa‐5,8,11,17‐tetraenoic, 11,12‐cis‐epoxy‐eicosa‐5,8,14,17‐tetraenoic, 8,9‐cis‐epoxy‐eicosa‐5,11,14,17‐tetraenoic and 5,6‐cis‐epoxy‐eicosa‐8,11,14,17‐tetraenoic acids. The total epoxide yield from eicosapentaenoate was 10% per incubation. By reincubating (cycling) the unused substrate 10–20 times, the total epoxide yield could be increased to 66–88%. Epoxide regioisomers were not produced in equal amounts; epoxygenation was facilitated as the distance between the target double bond and carbomethoxy group increased. Upon hydrolyzing the epoxides, the gas‐chromatographic retention times and mass spectra of the diol products were found to match those of biological metabolites. In addition, each of these standards was rapidly and quantitatively synthesized in an amount (milligram) adequate for biological tests.
Nuclear magnetic resonance spectroscopic analysis of homoallylic andbis homoallylic substituted methyl fatty ester derivatives
Authors: Lie Ken Jie Marcel S. F. , Cheng K. L. 
Published: November 2006

AbstractUsing a combination of selective irradiation1H nuclear magnetic resonance experiments and two‐dimensional1H−13C correlation spectroscopy spectral analysis of homoallylic andbis homoallylic substituted (azido, acetoxy, chloro and oxo) fatty ester derivatives, the carbon shifts of the ethylenic carbon atoms were determined. In the case of methyl 12‐azido‐9Z‐octadecenoate (homoallylic), the carbon chemical shifts of the ethylenic C‐9 and C‐10 carbon nuclei are 133.092 and 124.596 ppm, respectively. In methyl 9‐azido‐12Z‐octadecenoate (bis homoallylic), the carbon chemical shift of the ethylenic C‐12 and C‐13 carbon nuclei are 128.118 and 131.243 ppm, respectively.
Analysis of lipoxygenase kinetics by high‐performance liquid chromatography with a polymer column
Authors: Nuñez Alberto , Piazza George J. 
Published: November 2006

AbstractSoybean lipoxygenase (LOX; EC 1.12.11.12) catalyzes the oxygenation of polyunsaturated fatty acids, acylglycerols and phosphoglycerols, producing a regio‐and enantiospecific hydroperoxide product. The goal of this work was to measure the relative rate of LOX‐catalyzed oxidation of mixtures of lipids containing linoleate, using high‐performance liquid chromatography (HPLC) and a light‐scattering detector (LSD). Previous literature sugested that reversed‐phase HPLC with silicabased columns could be used for the separation of individual fatty acids, acylglycerols, phosphoglycerides and their oxidation products. However, these columns produced ineffective separations of phosphoglycerides unless choline chloride and a strong base, such as KOH, are present in the mobile phase. Such modifiers precluded the use of the LSD. It was found that a reversed‐phase column based upon an organic polymer support, rather than on silica, was able to separate these mixtures with a ternary solvent gradient of methanol/water/acetonitrile without the need for the addition of modifiers. The oxidation time course of a mixture of linoleic acid, trilinolein and 1‐linoleoyl‐2‐stearoyl‐sn‐glycero‐3‐phosphocholine was followed using the developed HPLC method. The results showed that trilinolein and phosphatidylcholine reacted at one‐tenth the rate of linoleic acid. The diacylglycerol, 1,3‐dilinolein, was oxidized at a rate that was approximately 40% that of linoleic acid, with the formation of mono‐and dihydroperoxides as well as other unidentified products.
Effect ofd‐α‐tocopherol analogues on lipoxygenase‐dependent peroxidation of phospholipid‐bile salt micelles
Authors: Arai Hirofumi , Nagao Akihiko , Terao Junji , Suzuki Tetsuya , Takama Kozo 
Published: November 2006

AbstractIn order to know whether or not vitamin E acts as an effective antioxidant in lipoxygenase‐dependent peroxidation of phospholipids, the effect of vitamin E and vitamin E analogues, 2,2,5,7,8‐pentamethyl‐6‐hydrohychroman (PMC) and 6‐hydroxy‐2,5,7,8‐tetramethylchroman‐2‐carboxylic acid (Trolox C), was investigated in enzymatic lipid peroxidation of bile salt micelles of pig liver phosphatidylcholine (PC) using soybean lipoxygenase. 15‐Hydroperoxy‐5,8,11,13‐eicosatetraenoic acid was exlusively produced by the reaction with the PC molecular species containing arachidonic acid moiety, indicating that the hydroperoxidation of pig liver PC entirely progresses through the enzymatic reaction. PMC suppressed the accumulation of PC‐hydroperoxides (PC‐OOH) more efficiently than eitherd‐α‐tocopherol (α‐Toc) or Trolox C, and 50% inhibition concentration by PMC was close to that of quercetin, a known lipoxygenase inhibitor from natural origin. The antioxidant activity of PMC was also superior to that of either α‐Toc or Trolox C in ferrous ion‐induced nonenzymatic oxidation of PC micelles in the presence of a trace amount of PC‐OOH, although the radical‐scavenging activities of these compounds in solution were similar or comparable to one another. In conclusion, PMC is more effective than α‐Toc as an inhibitor of lipoxygenase reaction with phospholipids and of autoxidation in phospholipids. The phytyl chain of α‐Toc seems to be unfavorable for exerting an inhibitory effect on lipoxygenase reaction with phospholipid‐bile salt micelles.
Protective effect of estrogens and catecholestrogens against peroxidative membrane damagein vitro
Authors: Lacort Mercedes , Leal Ana M. , Liza Mariana , Martín César , Martínez Rosa , Ruiz‐Larrea M. Begoña 
Published: November 2006

AbstractThe antioxidant effects of natural estrogens (estrone E1; 17β‐estradiol), synthetic estrogens (17α‐ethynylestradiol, EE2; mestranol, MES; diethylstilbestrol, DES) and catechle‐strogens (2‐hydroxyestradiol; 4‐hydroxyestradiol 4‐OHE2) on lipid peroxidation induced by different means in rat liver microsomes were investigated. The extent of lipid peroxidation was determined by measuring thiobarbituric acid reactive substances. Prooxidants included Fe3+/ADP/reduced NADPH, Fe2+/ascorbate,tert‐butyl hydroperoxide (t‐BOOH) and 2,2′‐azobis (2‐amidinopropane) (AAPH). Estrogens and catecholestrogens decreased lipid peroxidation in all four systems tested. In the iron/ascorbate model it was shown that (i)‐OHE2 and DES had analogous patterns of inhibition, irrespective of the presence of NADPH or the functional integrity of the microsómes, and (ii) the antioxidant activities of E1, EE2 and MES were dependent on the assay conditions with the activity being markedley higher when estrogen metabolism was favored. When peroxidation was initiated by the peroxyl radical generator AAPH, the inhibitory effects observed were least pronounced. Our data also showed that, in each of the systems, all inhibitors displayed the same order of inhibitory potency with DES and catecholestrogens being the most potent antioxidants under all experimental conditions used. The present results confirm earlier findings and point toward a link between estrogen metabolism and estrogen antioxidant activity. The data also indicate that estrogens and catecholestrogens interact with the peroxidative process at different levels with their interactions with iron or the metal‐derived species being the most important modes of inhibition.
Effect of reproductive states on lipid mobilization and linoleic acid metabolism in mammary glands
Authors: Bandyopadhyay Gautam K. , Lee Le‐Young , Guzman Raphael C. , Nandi Satyabrata 
Published: November 2006

AbstractEffects of pregnancy and lactation on lipid metabolism in mouse mammary fat pads and nonmammary adipose tissues have been studied. In order to address the question whether the influence of hormonal milieu on lipid metabolism in mammary epithelial cells during pregnancy and lactation is the same as in fat cells, we have studied the mobilization of lipids and metabolism of fatty acids in the intact mammary glands, parenchyma‐free mammary fat pads and in the perimetrial fat tissues of virgin, pregnant and lactating mice. Compared to parenchyma‐free mammary fat pads, the perimetrial adipose tissues accumulated 5‐fold higher levels of triglycerides during pregnancy. Mammary fat cells maintained overall lipid levels during pregnancy and lactation (16–20 μg/fat pad). In contrast, lactation depleted total lipid stores from 108 ± 5 to 24 ± 4.5 μg/fat pad in perimetrial fat pads. Results of comparative analysis of fatty acid composition of mammary fat pads, with and without epithelial tissue, from virgin and lactating mice showed stimulation of 18∶2ω6 metabolism leading to 130% increase in the ratio 20∶4ω6 to 18∶2ω6 in the epithelial compartment. Pregnancy and lactation resulted in the elevation of 20∶4ω6 levels probably due to a 4‐fold increase in Δ5 desaturase activity and a decrease in oxidative degradation of 18∶2ω6. These results suggest that, unlike other adipose tissues, the metabolic pathways in mammary fat cells are not dedicated to sequestration and accumulation of dietary lipids during pregnancy. Lactation favors mammary epithelial cell‐stimulated production of precursors of eicosanoids which are known to have agonist‐like effect on mammary epithelial cells.
1‐O‐alkyl‐2,3‐diacylglycerols in the skin surface lipids of the hairless mouse
Authors: Oku Hirosuke , Shudo Jyutaro , Mimura Kunio , Haratake Akinori , Nagata Junichi , Chinen Isao 
Published: November 2006

AbstractA neutral lipid class was isolated by thin‐layer chromatography from the skin surface lipids of the hairless mouse. The fraction migrated faster than triglycerides and had a migration rate similar to that of diacyl alkanediols (diester wax). Upon deacylation, however, the long‐chain diols were identified as 1‐alkylglycerol ethers based on their chromatographic properties and on the mass spectra of their nicotinylidene derivatives. Thus, the skin lipid fraction was identified as 1‐O‐alkyl‐diacylglycerol. The alkyl moieties were all saturated and even‐numbered and ranged in chainlength from C16 to C22 with 1‐O‐hexadecylglycerol amounting to 34% of the total glycerol ether moieties. The fatty acids derived from this lipid fraction were mostly monoenoic with chainlengths ranging from C16 to C24. The major acyl component was eicosenoic acid (20∶1) representing 61% of the total fatty acids.
Analysis of triglycerides using atmospheric pressure chemical ionization mass spectrometry
Authors: Byrdwell Wm. Craig , Emken Edward A. 
Published: November 2006

AbstractAtmospheric pressure chemical ionization (APCI) mass spectrometry was investigated as a new method for analysis of a mixture of triglycerides separated by reverse‐phase high‐performance liquid chromatography. A mixture of homogeneous (monoacid) triglyceride standards containing fatty acids with zero to three double bonds was analyzed to demonstrate the quality of mass spectra obtained by using the APCI interface. The mass spectra showed that minimal fragmentation occurs, resulting primarily in diglyceride [M−RCOO]+ ions and [M+1]+ protonated molecular ions. The degree of unsaturation within the acyl chains had a marked effect on the proportion of diglyceride ions vs. the [M+1]+ ions formed in the APCI source. The mass spectra of triglycerides containing fatty acids with two or three double bonds showed predominantly protonated triglyceride ions, with diglyceride peaks representing 13 to 25% of the base peak. The triglycerides containing singly unsaturated fatty acids gave diglyceride ions as the base peak, and [M+1]+ ions with an intensity 20 to 28% that of the base peak. Only diglyceride ions were observable in the spectra of triglycerides containing saturated fatty acids.