bluuebunny/crossref_metadata_2025_split huggingface dataset:
Preparation and characterization of glucosylated aminoglycerophospholipids
Authors: Ravandi A. , Kuksis A. , Myher J. J. 
Published: November 2006

AbstractNatural aminophospholipids were isolated from egg yolk and from human red blood cells. Glucosylated ethanolamine and serine phosphatides were prepared by exposing synthetic and natural aminophospholipids to glucose for 3–18 h at pH 7.4. The glucosylation products were resolved from parent phospholipids by normal‐phase high‐performance liquid chromatography and were identified by on‐line mass spectrometry with an electrospray interface. The soft ionization method allowed us to detect the glucosylation products as molecular ions of the Schiff bases. The Schiff bases could be stabilized by sodium cyanoborohydride reduction. The molecular species of the ethanolamine and serine phosphatides reacted in proportion to their molar concentration in the mixtures. The yields of the glucosylation products varied with time of reaction and the concentration of glucose in the medium. At 50 mM glucose and 0.6 mg/mL phosphatidylethanolamine, 20% of the aminophospholipid was glycated in 18 h at 37°C.
Structural importance of thecis‐5 ethylenic bond in the endogenous desaturation product of dietary elaidic acid,cis‐5,trans‐9 18∶2 acid, for the acylation of rat mitochondria phosphatidylinositol
Authors: Wolff Robert L. 
Published: November 2006

AbstractWhen rats were fed elaidic (trans‐9 18∶1) acid at a high load in diets that were otherwise marginally or almost completely deficient in linoleic (cis‐9,cis‐12 18∶2) acid, elaidic acid was desaturated tocis‐5,trans‐9 18∶2 acid. This polymethylene‐interrupted acid was then incorporated into most phospholipids from rat mitochondria, cardiolipin being an exception. Its level of esterification in phospholipids followed the increasing order: phosphatidylethanolamine <phosphatidylcholine < phosphatidylinositol (PI). The content ofci‐5,trans‐9 18∶2 acid decreased in organs in the order liver > kidney > heart. The levels ofcis‐5,trans‐9 18∶2 acid increased in mitochondria phospholipids as the level of linoleic acid was lowered in the diet. In liver mitochondria PI, it reached 16% of total fatty acids. After hydrolysis of liver mitochondria PI withNaja naja phospholipase A2, we observed that elaidic acid was essentially esterified to position 1 at the expense of saturated acids, whereascis‐5,trans‐9 18∶2 acid was exclusively esterified to position 2, along with 20∶3n−9 and 20∶4n−6 acids. As a consequence, the sums of saturated andtrans‐9 18∶1 acids on the one hand, and of 20∶3n−9, 20∶4n−6, andcis‐5,trans‐9 18:2 acids on the other hand, remained fairly constant in liver mitochondria PI (ca. 55 and 30%, respectively). Becausetrans‐9 18∶1 andcis‐5,trans‐9 18∶2 acids differ only by thecis‐5 ethylenic bond, which is also present in 20∶3n−9 and 20∶4n−6 acids, this distribution pattern indicates that thecis‐5 double bond, rather than any other ethylenic bond, may be of major structural importance for channeling fatty acids to position 2 of PI.
A temperature‐sensitive strain ofHistoplasma capsulatum has an altered Δ9‐fatty acid desaturase geneacid desaturase gene
Authors: Gargano Silvana , Di Lallo Gustavo , Kobayashi George S. , Maresca Bruno 
Published: November 2006

AbstractWe have isolated and characterized the Δ9‐desaturase gene (Ole1), which codes for a key enzyme involved in regulating membrane fluidity in animal cells and microorganisms, from two strains ofHistoplasma capsulatum, one that is temperature‐tolerant (G217B) and the other temperature‐susceptible (downs). These pathogenic fungi are dimorphic in that they undergo a morphologic transition from the mycelial to yeast‐like form when the temperature of incubation is switched from 25 to 37°C or when they infect a susceptible host. The coding sequences of the two genes, both containing an intron of 93 nucleotides, arevirtually identical and analogous to the Δ9‐desaturase gene ofSaccharomyces cerevisiae and those of the rat, mouse and human.Ole1 transcription of the thermotolerant G217B and thermosensitive Downs strains is similar in yeast phase cells and during the temperature shift down from 34, 37, or 40 to 25°C (yeast‐to‐mycelia transition). Nevertheless, Δ9‐desaturase gene is transcriptionally inactive in mycelia of G217B at 25°C while it is actively transcribed in the Downs strain at the same temperature. These results are in agreement with the finding that membranes of the Downs strain have a higher level of oleic acid. The differential expression of Δ9‐desaturase genes is discussed in relationship to differences in thermosensitivity in the fungal isolates and in regulating the level of expression of heat shock genes.
Intestinal and liver fatty acid binding proteins differentially affect fatty acid uptake and esterification in L‐cells
Authors: Prows Daniel R. , Murphy Eric J. , Schroeder Friedhelm 
Published: November 2006

AbstractDifferential effects of intestinal (I‐FABP) or liver (L‐FABP) fatty acid binding proteins on fatty acid uptake and esterification were examined using transfected mouse L‐cell fibroblasts. L‐FABP, but not I‐FABP, expression increased the initial rate and extent ofcis‐parinaric acid uptake by 50 and 29%, respectively, compared to control cells. I‐FABP and L‐FABP expression preferentially increased [3H]‐oleic acid incorporation into triacylglycerols by 5.5‐fold and 3.8‐fold, respectively. While both L‐FABP and I‐FABP increasedesterification of [3H]‐oleic acid into ethanolamine glycerophospholipids, these proteins had opposite effect on esterification into choline glycerophospholipids. These data show for the first time that distinct FABP differentially affect both fatty acid uptake and intracellular esterification.
Effects of randomization of partially hydrogenated corn oil on fatty acid and cholesterol absorption, and tissue lipid levels in rats
Authors: Koga Tamiho , Yamato Takako , Ikeda Ikuo , Sugano Michihiro 
Published: November 2006

AbstractRandomization of partially hydrogenated corn oil containing approximately 45% oftrans octadecenoic acid only slightly, but not significantly, increased the lymphatic fatty acid absorption in rats. No effect of randomization was observed on cholesterol absorption. When rats were fed these fats at the 8.8% level (with 1.2% safflower oil) for three weeks, the concentrations of serum cholesterol, and serum and liver phospholipid were significantly higher in randomized fat than in control fat, which was composed of 9% high‐oleic safflower oil and 1% palm oil. Liver cholesterol tended to be higher in randomized fat. In contrast, nonrandomized fat was not hyperlipidemic compared to control fat. Although the fatty acid composition of liver phospholipids suggested a possible interference oftrans fatty acid with the metabolism of linoleic acid to arachidonic acid, there was no effect of randomization. In the two hydrogenated fat groups,trans octadecenoic acid was incorporated and distributed similarly in adipose tissue triacylglycerol. These observations indicated that randomization of partially hydrogenated fat is not beneficial to various lipid parameters in rats.
Erythrocyte fatty acids of term infants fed either breast milk, standard formula, or formula supplemented with long‐chain polyunsaturates
Authors: Makrides Maria , Neumann Mark A. , Simmer Karen , Gibson Robert A. 
Published: November 2006

AbstractThe purpose of our study was to assess whether a supplement of fish oil (FO) and evening primrose oil (EPO) for formula‐fed infants was capable of avoiding reductions in erythrocyte docosahexaenoic acid (DHA, 22∶6n−3) and arachidonic acid (AA, 20∶4n−6) associated with standard formula feeding. Healthy, term infants, whose mothers chose to formula feed, were randomized to either a placebo or supplemented formula for their first 30 wk of life. A reference group of beast‐fed infants also was enrolled. Erythrocyte fatty acids were measured by capillary gas chromatography on day 5 and in weeks 6, 16, and 30. Supplementation of formula with 0.36% of total fatty acids as DHA resulted in erythrocyte DHA being maintained at or above breast‐fed levels for the entire 30‐wk study period, and breast feeding (0.21% DHA) resulted in a modest fall in erythrocyte DHA relative to baseline (day 5) values. The level of erythrocyte DHA in placebo formula‐fed infants was halved by week 16. AA levels decreased in all infants in the first six weeks, but the levels in breast‐ and placebo formula‐fed infants increased with age and returned to approximate baseline (day 5) values by 16 and 30 wk of age, respectively. Erythrocyte AA in FO+EPO‐supplemented infants remained low and below breast‐ and placebo formula‐fed levels. Our data suggest that dietary supplementation with DHA at 0.36% total fatty acids results in erythrocyte DHA levels above those found in breast‐fed infants. EPO supplementation was not effective at maintaining erythrocyte AA when given with FO.
Differences in fatty acid composition of immature and mature articular cartilage in humans and sheep
Authors: Cleland Katherine A. , James Michael J. , Neumann Mark A. , Gibson Robert A. , Cleland Leslie G. 
Published: November 2006

AbstractChondrocytes are imbedded in an avascular, highly charged extracellular matrix which could form a barrier to the transfer of dietary essential fatty acids (EFA) to chondrocytes. A study was designed to assess the composition of immature and mature joint cartilage with respect to essential and nonessential fatty acids relevant to EFA deficiency. Cartilage and muscle samples were obtained from human fetus, infant and adult cadavers, and from fetal and mature sheep. Lipid extracts were prepared and the fatty acid composition determined. In human and sheep joint cartilage, linoleic acid (LA; 18∶2n−6) content was lower, and n−9 eicosatrienoic acid (ETrA; 20∶3n−9) and arachidonic acid (AA; 20∶4n−6) were higher in fetuses compared to mature subjects. An intermediate pattern was seen in infant cartilage. n−3 Fatty acids tended to be higher in fetal than in mature cartilage in humans and in sheep. In human muscle (and in other noncartilaginous comparison tissues), similar differences between fetuses and adults were seen in LA and AA, but not in ETrA. In fetal sheep muscle, very low LA, reduced AA and raised ETrA levels compared to mature sheep muscle were seen. However, although the pattern is characteristic of EFA deficiency, the abundance of n−6 EFA in liver and spleen of human fetuses and of n−3 EFA in liver and spleen of fetal sheep suggests that placental transfer of EFA is not likely to be limiting. During fetal development, the metabolism of fatty acids is distinctive and differs between the species. ETrA appears to be a readily measurable component of some tissues at certain stages of development when its presence in tissues does not indicate EFA deficiency.
Modulation by sphingosine of substrate phosphorylation by protein kinase C in bovine mammary gland
Authors: Katoh Norio 
Published: November 2006

AbstractThe effect of sphingosine on the phosphorylation of endogenous proteins by protein kinase C (PKC) was investigated in bovine mammary gland. Several proteins were shown to be substrates for PKC in both cytosolic and total particulate fractions by phosphorylation in the absence or presence of 1‐oleoy‐2‐acetyl‐sn‐glycerol, phosphatidylserine (PS) and Ca2+. At concentrations of 83 μM or less, sphingosine inhibited phosphorylation of several substrates for PKC in both fractions. Phosphorylation of cytosolic 36 kDa, 21 kDa and particulate 36 kDa proteins was particularly sensitive to sphingosine. Cytosolic 97 kDa phosphorylation (which was enhanced by Ca2+ alone) was also sensitive to sphingosine. The inhibition was reversed by excess addition of lipid cofactors, particularly PS, but not by Ca2+. At higher concentrations (167 and 417 μM), in addition to the inhibition seen at lower concentrations, sphingosine stimulated phosphorylation of several proteins, including cytosolic 19 kDa and particulate 53 kDa, which were not detected in the absence of sphingosine. The sphingosine‐induced phosphorylation disappeared with excess addition of PS, but not with addition of Ca2+. The results point toward the importance of the interaction of sphingosine with membrane phospholipids in the signal transduction pathway mediated by PKC‐dependent phosphorylation in bovine mammary gland.
Intravenous injection of tridihomo‐γ‐linolenoyl‐glycerol into mice and its effects on delayed‐type hypersensitivity
Authors: Taki Hirofumi , Nakamura Norio , Hamazaki Tomohito , Kobayashi Masashi 
Published: November 2006

AbstractHighly purified tridihomo‐γ‐linolenoyl‐glycerol (DGLA‐TG) was emulsified with egg yolk lecithin as a 10% (wt/vol) DGLA‐TG emulsion. We injected 0.05 or 0.5 mL of the emulsion into mice through the tail vein and investigated its effects on the fatty acid composition of spleen cells and on delayed‐type hypersensitivity (DTH) response. At 1 h after the injection, dihomo‐γ‐linolenic acid (DGLA) concentrations were increased significantly in the total phospholipid fraction of spleen cells from 1.21±0.13 mol% to 2.09 ±0.74 mol% (P<0.02) and 7.95±1.25 mol% (P<0.001) in the 0.05‐mL and 0.05‐mL groups respectively. Mice, which had already been immunized with sheep red blood cells (SRBC), were challenged by the injection of SRBC into the right‐hind footpad. Intravenous injection into mice with 0.5 mL of the emulsion immediately before the challenge almost completely suppressed DTH response measured by the swelling of the right‐hind footpads 24 h thereafter. This inhibitory effect on the DTH response was significant with as little as 0.05 mL of the emulsion, whereas a soybean oil emulsion was not effective at all. In conclusion, intravenous injection of a DGLA emulsion increased DGLA concentrations in immune cells within 1 h and suppressed the DTH reaction.
pH‐dissociation characteristics of cardiolipin and its 2′‐deoxy analogue
Authors: Kates Morris , Syz Jing‐Yi , Gosser David , Haines Thomas H. 
Published: November 2006

AbstractCardiolipin (CL) is found in inner mitochondrial membranes and the plasma membrane of aerobic prokaryotes. CL is tightly bound to those transmembrane enzymes associated with oxidative phosphorylation. CL has earlier been reported to have a single pK at low pH. We have titrated CL in aqueous suspension (bilayers) and in solution in methanol/water (1∶1, vol/vol) and found it to display two different pK values, pK1 at 2.8 and pK2 initially at 7.5 but shifting upwards to 9.5 as the titration proceeds. The unusually high pK2 might be explained by the formation of a unique hydrogen bond in which the free hydroxyl on the central glycerol forms a cyclic intramolecular hydrogen‐bonded structure with one protonated phosphate (P‐OH group). We have therefore chemically synthesized the 2′‐deoxycardiolipin analogue, which lacks the central free hydroxyl group, and measured its pH‐dissociation behavior by potentiometric titration, under the same conditions as those for CL. The absence of the hydroxyl group changes the titration dramatically so that the deoxy analogue displays two closely spaced low pK values (pK1=1.8; pK2=4.0). The anomalous titration behavior of the second dissociation constant of CL may be attributed to the participation of the central glycerol OH group in stabilizing the formation of a cyclic hydrogen‐bonded monoprotonated form of CL, which may function as a reservoir of protons at relatively high pH. This function may have an important bearing on proton pumping in biological membranes.
Modulating effects of bile salt hydrophobicity on bile secretion of the major protein of the bile lipoprotein complex
Authors: Domingo Nicole , Chanussot Françoise , Botta Danielle , Reynier Marie‐Odile , Crotte Christian , Hauton Jacques , Lafont Huguette 
Published: November 2006

AbstractBile lipids are secreted in association with a newly identified major apoprotein called anionic polypeptide fraction‐calcium binding protein (APF‐CBP), which is synthesized in the hepatocytes and has been detected in both bile and plasma and characterized. The secretion of the lipids in bile depends both on the concentration and the hydrophobicity of the bile salts (BS) secreted. The present study was undertaken to determine whether the synthesis and the secretion of APF‐CBP are similarly regulated by BS, using two methods. The synthesis and secretion of labelled, newly synthesized APF‐CBP by isolated rat hepatocytes were monitored by solid‐phase immunoassay. For this purpose, hepatocytes were incubated with either glycodeoxycholate (GDC) or taurocholate (TC). The synthesis and secretion of labelled, newly synthesized APF‐CBP by perfused rat liver were measured by immunological enzyme‐linked assay (ELISA) upon perfusing the liver with either GDC or TC. We found that (i) the synthesis and the secretion of APF‐CBP were increased during either TC or GDC perfusion, but the increase was more pronounced with TC; (ii) in GDC perfusion the APF‐CBP levels measured were more closely related to the levels of bile salts and not to phospholipid levels, (iii) when the two bile salts were perfused in reverse order,i.e., first GDC and then TC, the secretion of APF‐CBP in bile decreased when GDC was perfused, but increased when TC was perfused. Similar results were obtained in experiments with isolated hepatocytes. The data suggest that the hydrophobicity of the BS used in the infusion modulates the synthesis and secretion of APF‐CBP. In the liver, the pool of APF‐CBP can be modified by BS and responds rapidly to BS stimulation.
On the syntheses of branched saturated fatty acids
Authors: Gronowitz Salo , Klingstedt Tomas , Svensson Leif , Hansson Ulf 
Published: November 2006

AbstractIn order to investigate the relation between the structure of mono‐branched saturated fatty acids and their physical properties, a three‐factor central composite design was constructed. For this purpose sixteen different fatty acids were prepared. The synthetic strategy was to use if possible, a few common starting materials for the preparation of most of the acids. Thus alkylation and hydrolysis of oxazolines were used for the preparation of 2‐butylhexanoic acid, 2‐methyloctadecanoic acid, 2‐hexadecyloctadecanoic acid and 2‐pentyloctadecanoic acid. A number of acids were prepared from thiophene derivatives followed by desulfurization with Raney‐Nickel alloy under alkaline conditions. Thus, starting from 3‐ethylthiophene, 4‐ethyl‐2‐thiophenecarboxylic acid and 4‐ethyl‐2‐methyl‐5‐thiophenecarboxylic acid were prepared, which upon desulfurization gave the desired 4‐methylhexanoic acid. From 3‐bromo‐2‐methylthiophene, 3‐ethyl‐2‐methyl‐5‐thiophenecarboxylic acid was preparedvia 3‐acetyl‐2‐methylthiophene and 3‐ethyl‐2‐methylthiophene. Desulfurization gave 4‐ethylhexanoic acid. Another approach started with 2‐acylthiophenes, which were reacted with Grignard reagent to yield the appropriate olefins. By metalation and reaction with carbon dioxide, these were transformed to the corresponding 2‐thiophenecarboxylic acids. Upon desulfurization, the desired fatty acids were obtained. In this way 6‐propyldecanoic acid, 6‐hexyldodecanoic acid, 6‐methyldodecanoic acid and 6‐pentylpentadecanoic acid were prepared. The remaining four acids were prepared from some of the branched acids described above through Kolbe reactions of dioic acids. Thus 16‐methyloctadecanoic acid and 10‐methyl‐dodecanoic acid were obtained from 4‐methylhexanoic acid, 16‐ethyloctadecanoic acid from 4‐ethylhexanoic acid and 9‐pentyloctadecanoic acid from 6‐pentylpentadecanoic acid.
Effect of lipid content of diet on cholesterol content and cholesterogenic enzymes of European eel liver
Authors: Burgos C. , Zafra M. F. , Castillo M. , Garcia‐Peregrin E. 
Published: November 2006

AbstractThe effect of dietary lipid levels on the levels of cholesterol and the activities of the major cholesterogenic enzymes of the liver has been studied in the European eel. An increase in hepatic total cholesterol was observed when the dietary lipid levels increased from 12 to 20%, while protein levels were maintained at 30%. This change paralleled an increase in mevalonate 5‐pyrophosphate decarboxylase activity, while 3‐hydroxy‐3‐methylglutaryl‐CoA reductase, mevalonate kinase and mevalonate 5‐phosphate kinase were not affected by changes in diet composition. These results suggest that the decarboxylase may be a rate‐limiting enzyme in cholesterogenesis in eel liver.
Cholesterol and 25‐hydroxycholesterol retention in specimens of liver and aorta prepared for electron microscopy. I. Standard fixation methods and metabolism of the labeled sterols
Authors: Fornas E. , Renau‐Piqueras J. , Fortea A. , Mayordomo F. , Alborch E. 
Published: November 2006

AbstractIn the present work, several preparatory procedures commonly used for electron microscopy (EM) were evaluated as to their ability to preserve cholesterol (CHO) and CHO derivatives in tissue. We also determined in several rat tissues to what extent the sterols used as tracers are metabolized. Sprague‐Dawley rats were injected intraperitoneally with [1α,2α(n)‐3H]cholesterol ([3H]CHO) and 25‐hydroxy‐[26,27‐3H]cholesterol ([3H]25‐OH−CHO). Lipids of the liver, aorta and brain were extracted one and five days after injection, and the distribution of the labeled lipids was followed by thin‐layer chromatography. When labeled CHO was injected as tracer, most of the radioactivity remained associated with the CHO fraction. When 25‐hydroxycholesterol (25‐OH−CHO) was used, we found that it was mostly metabolized to yield more polar compounds. Our results show that the loss of CHO and CHO derivatives from tissues depends not only on the preparatory procedure used for EM, but also on the type of tissue studied.
The effect of lyophilization on the solvent extraction of lipid classes, fatty acids and sterols from the oysterCrassostrea gigas
Authors: Dunstan Graeme A. , Volkman John K. , Barrett Stephanie M. 
Published: November 2006

AbstractThe lipid class compositions of adult Pacific oysters [Crassostrea gigas (Thunberg)] were examined using latroscan thin‐layer chromatography/flame‐ionization detection (TLC/FID), and fatty acid compositions determined by capillary gas chromatography and gas chromatography/mass spectrometry (GC/MS). The fatty acid methyl esters were separated using argentation TLC and also analyzed as their 4,4‐dimethyloxazoline derivatives using GC/MS. Major esterified fatty acids inC. gigas were 16∶0, 20∶5n−3, and 22∶6n−3. C20 and C22 nonmethylene interrupted (NMI) fatty acids comprised 4.5 to 5.9% of the total fatty acids. The NMI trienoic fatty acid 22∶3(7,13,16) was also identified. Very little difference was found in the proportions of the various lipid classes, fatty acids or sterols between samples of adult oysters of two different sizes. However, significant differences in some of the lipid components were evident according to the method of sample preparation used prior to lipid extraction with solvents. Lyophilization (freeze drying) of samples led to a significant reduction in the amounts of triacylglycerols (TG) extracted by solvents in two separate experiments (7.0 and 52.5% extracted). Extracts from lyophilized samples had less 16∶0, C18 unsaturated fatty acids, and 24‐ethylcholest‐5‐en‐3β‐ol, while C20 and C22 unsaturated fatty acids comprised a higher proportion of the total fatty acids. There was no significant change in the amounts of polar lipids, total sterols, free fatty acids or hydrocarbons observed in extracts from lyophilized samples relative to extracts from nonlyophilized samples. Addition of water to the freezedried samples prior to lipid extraction greatly improved lipid yields and resulted in most of the TG being extracted.