bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of dietary fat on the fatty acid composition of lipids secreted in rats' milk
Authors: Brandorff Nanna Philipson 
Published: December 2006

AbstractDuring pregnancy and lactation, female rats were fed diets containing either 28% partially hydrogenated marine oil (28MO), 2% arachis oil (2AO), or no fat (FF). Milk lipid composition was examined by gas chromatographic analysis of the gastric content of 10‐day‐old suckling pups. An increase to 45% in the milk content of long chain monoenoic acids, 18∶1, 20∶1 and 22∶1, reflects the fatty acid composition of the marine oil. Milk fatty acids of medium chain length comprised 6%, 31% and 24% of total fatty acids in the (28MO), (2AO) and (FF) groups, respectively, suggesting that a high‐fat diet (28MO) inhibits the lipid synthetic activity of mammary glands. The amount of dienoic C18‐acids (6%) in the group fed (28MO) containing no essential fatty acids (EFA) was similar to the amount of 18∶2 in the group receiving a low‐fat, EFA‐rich diet (2AO). However, only half the dienoic acid from the milk of the (28MO)‐fed animals was linoleic acid, which was most likely mobilized from fat depots.
Complex formation in sonicated mixtures of β‐lactoglobulin and phosphatidylcholine
Authors: Brown Eleanor M. , Carroll Robert J. , Pfeffer Philip E. , Sampugna Joseph 
Published: December 2006

Abstractβ‐Lactoglobulin, the major whey protein of bovine milk, is secreted via the endomembrane system of the mammary gland. The primary structure of β‐lactoglobulin shares certain characteristics with membrane proteins, although the soluble protein assumes a globular conformation. We have prepared complexes of β‐lactoglobulin and phosphatidylcholines by dissolving both in a helix‐forming solvent (chloroform methanol). The complex is stable when transferred to aqueous solutions and sonicated to form vesicles. Both ionic and hydrophobic interactions appear to be involved in complex formation. We have used spectroscopy (circular dichroism, fluorescence, and nuclear magnetic resonance) and electron microscopy to study these complexes. At pH 3.7, the small, single bilayer vesicles produced by sonication are protected against aggregation by the presence of the protein. As determined by circular dichroism, the proportion of α‐helix in β‐lactoglobulin is increased by complexation with phosphatidylcholine. Circular dichroism and fluorescence spectra show the involvement of at least 1 tryptophan residue in the conformational change. At pH 7.2, β‐lactoglobulin‐phosphatidylcholine vesicles form aggregates as observed by electron microscopy and31P nuclear magnetic resonance spectroscopy. These aggregated vesicles could be resuspended by raising the pH. The ability of the partially unfolded β‐lactoglobulin to interact with lipids is believed to be important to its transport through the endomembrane system.
The influence of chenodeoxycholic acid on cholesterol and bile acid turnover in humans with cholelithiasis
Authors: Quarfordt S. H. , Jain R. , Greefield M. R. 
Published: December 2006

AbstractThe in vivo dynamics of cholesterol were determined in 8 individuals who were part of a national double‐blind study testing the efficacy of chenodeoxycholic acid ingestion on the dissolution of gallstones. Despite the ingestion of this bile acid in amounts in excess of its normal endogenous flux, the conversion of neutral sterol to chenodeoxycholic acid continued. The flux of neutral sterol to endogenous chenode‐oxycholate was lower for the patients ingesting bile acid than for one of the patients on placebo, but was similar to that of the other control and similar to previously published chenodeoxycholate flux in patients with cholesterol cholelithiasis. The remaining flux was on the basis of the very efficiently absorbed dietary chenodeoxycholate. The total cholesterol fractional catabolic rate and flux were not appreciably diminished by the administration of either high or low dose chenodeoxycholate to these individuals with cholesterol cholelithiasis.
The influence of linoleic acid intake on the kinetics of adenine nucleotide translocase
Authors: Mak I. T. , Shrago E. , Elson C. E. 
Published: December 2006

AbstractDietary enrichment of mitochondrial polyenoic fatty acid content was associated with increased respiratory activity (Abuirmeileh and Elson). The influence of the membrane lipid composition on the adenine nucleotide translocase (AdNT) was studied in rats that were fed diets formulated with beef tallow (BT) to provide low or safflower oil (SO) to provide high contents of linoleic acid. The phosphatidylcholine/phosphatidylethanolamine ratio was 40% higher in the SO mitochondria due primarily to an increase in phosphatidylcholine. SO mitochondria exhibited 25% higher state 3 respiration, 50% higher state 4 respiration and 13% higher net ADP‐dependent respiration than did the BT mitochondria. The relative RCR and ADP/O values of the SO mitochondria were slightly but significantly (p<0.01) lower. The kinetics of the AdNT were determined by the back exchange method (Pfaff and Klingenberg). At all assay temperatures, SO mitochondria exhibited a higher Km for ADP. However, addition of 5 mM carnitine to the assay mixture increased the affinity of the SO‐AdNT giving Km values similar to that of the BT‐AdNT. Washing the mitochondria with fat‐free BSA had a similar, but lesser, effect. At 25 C and 37 C, the Vmax of the SO‐AdNT were increased by 11–15% (p<0.05) which was independent of either BSA‐wash or the presence of carnitine. According to Dixon plot studies, the SO‐AdNT had a comparable Ki for atractylate but a slightly lower Ki for palmitoyl‐CoA inhibition. The accumulation of acyl‐CoA esters in the SO mitochondria was not ruled out. The overall results suggest that changes in mitochondrial membrane lipids accommodated an increased Vmax of the SO‐AdNT, which in turn accounted for that part of the increased state 3 respiration dependent on ADP translocation.
Effects of site‐directed mutagenesis on the serine residues of human lecithin: Cholesterol acyltransferase
Authors: Qu Shi‐Jing , Fan Hui‐Zhen , Blanco‐Vaca Francisco , Pownall Henry J. 
Published: December 2006

AbstractLecithin:cholesterol acyltransferase (LCAT) is a serine protease‐type enzyme that esterifies cholesterol in human plasma and is activated by apolipoprotein A‐I in high‐density lipoproteins. LCAT contains 22 serine residues, including Ser 181, which is thought to be part of the catalytic site. In order to determine the importance of these serine residues in LCAT, we prepared six LCAT mutants: LCAT (Ser19→Ala), LCAT (Ser181→Gly), LCAT (Ser208→Ala), LCAT (Ser216→Ala), LCAT (Ser225→Ala) and LCAT (Ser383→Ala). We also replaced the adjacent asparagine residues in two additional mutants, LCAT (Ser19→Ala, Asn20→Thr) and LCAT (Ser383→Ala, Asn384→Thr), in order to ascertain the effect of the serines onN‐glycosylation. The mutant complementary DNA (cDNA) were subcloned into a eukaryotic expression vector (pSG5) and expressed in COS‐6 cells. By polymerase chain reaction analysis, LCAT‐specific messenger RNA (mRNA) was found in all mutant and wild‐type transfectants. Western blot analysis revealed LCAT‐specific bands in media and lysates of the transfected cells. With two exceptions, the amounts of LCAT mass secreted by the transfectants were similar to that of the wild type (mean, 90% mass of wild type; range, 34–138%). Except for LCAT (Ser181→Gly), which was inactive, the specific activities of the remainder of the mutant enzymes were also similar (mean, 95% activity of wild type; range, 65–169%). These results indicate that Ser181 is part of the catalytic site and that stereoconservative substitutions for serines have minor effects on the synthesis, secretion and specific activities of human LCAT.
Interactions of MDL 29,311 and probucol metabolites with cholesteryl esters
Authors: McLean Larry R. , Brake Nick , Hagaman Karen A. 
Published: December 2006

AbstractThe hypothesis that the efficacy of hydrophobic antioxidants in animal models of atherogenesis may, in part, be related to physical effects on cholesteryl esters in cells was probed with analogs and metabolites of probucol. The interactions of an effectivebis‐thiomethane analog (MDL 29,311) and selected metabolites of probucol with cholesteryl oleate were examined by differential scanning calorimetry and polarized light microscopy. Like probucol, MDL 29,311 and the bisphenol metabolite decrease the liquid‐crystalline phase transition enthalpy of cholesteryl oleate with increasing concentrations. At 20 mol%, no transition is detectable. By contrast, the spiroquinone metabolite of probucol and the diphenoquinone metabolite common to both molecules have minimal effects on the liquid‐crystalline transitions of cholesteryl oleate. At 20 mol%, neither compound has as great an effect as 1 mol% MDL 29,311. Consistent with their effects on dry cholesteryl oleate, MDL 29,311 and the bisphenol metabolite convert lipid inclusions in cells supplemented with cholesterol to an isotropic physical state similar to that observed with probucol. The number of anisotropic inclusions in the cells decreases with increasing concentration in the medium in the range of 50 to 250 μg/mL. In cells fed with the spiroquinone or diphenoquinone metabolites, the lipid inclusions are liquid‐crystalline and resemble those observed with cholesterol‐fed controls. These data are interpreted in terms of a model in which hydrophobic antioxidants closely related to probucol disrupt the packing of cellular cholesteryl esters.
The n−3 polyunsaturated fatty acid levels in rat tissue lipids increase in response to dietary olive oil relative to sunflower oil
Authors: Navarro Maria D. , Periago José L. , Pita Maria L. , Hortelano Paloma 
Published: December 2006

AbstractIn the present study, changes in phospholipid compositions of liver microsomes, erythrocyte membranes, platelets, aorta, cardiac muscle and brain of rats fed olive oil were compared with those of rats fed sunflower oil. Four groups of rats starting at weaning were fed for four weeks a basal diet containing 5 or 25% olive oil or sunflower oil. We found that oleic acid was higher and linoleic acid was lower in membrane phospholipids of olive oil fed rats compared to sunflower oil fed rats. Polyunsaturated fatty acids of the n−3 series were markedly elevated in all tissues of rats on the olive oil diets relative to those on the sunflower oil diets. The results are consistent with a lower linoleic/linolenic acid ratio induced by the olive oil diets, suggesting a positive correlation between olive oil ingestion and n−3 polyunsaturated fatty acid levels in cell and tissue lipids. The study suggests that an adequate intake of olive oil may enhance the conversion of n−3 fatty acids.
Hematological and lipid changes in newborn piglets fed milk replacer diets containing vegetable oils with different levels of n−3 fatty acids
Authors: Kramer John K. G. , Sauer Frank D. , Farnworth Edward R. , Wolynetz Mark S. , Jones Gwynn , Rock Gail A. 
Published: December 2006

AbstractTo test if linolenic acid (18∶3n−3) from vegetable oils would affect bleeding times and platelet counts in new‐borns, piglets were used as a model fed milk replacer diets containing 25% (by wt) vegetable oils or oil mixtures for 28 d and compared to sow‐reared piglets. The oils tested included soybean, canola, olive, high oleic sunflower (HOAS), a canola/coconut mixture and a mixture of oils mimicking canola in fatty acid composition. All piglets fed the milk replacer diets showed normal growth. Bleeding times increased after birth from 4–6 min to 7–10 min by week 4 (P<0.001), and were higher in pigs fed diets containing 18∶3n−3, as well as in sowreared piglets receiving n−3 polyunsaturated fatty acids (PUFA) in the milk, as compared to diets low in 18∶3n−3. Platelet numbers increased within the first week in newborn piglets from 300 to 550×109/L, and remained high thereafter. Milk replacer diets, containing vegetable oils, generally showed a transient delay in the rise of platelet numbers, which was partially associated with an increased platelet volume. The oils showed differences in the length of delay, but by the third week of age, all platelet counts were >500×109/L. The delay in rise in platelet counts appeared to be related to the fatty acid composition of the oil, as the effect was reproduced by a mixture of oils with a certain fatty acid profile, and disappeared upon the addition of saturated fatty acids to the vegetable oil. There were no alterations in the coagulation factors due to the dietary oils. Blood plasma, platelets and red blood cell membranes showed increased levels of 18∶3n−3 and long‐chain n−3 PUFA in response to dietary 18∶3n−3. The level of saturated fatty acids in blood lipids was generally lower in canola and HOAS oil‐fed piglets as compared to piglets fed soybean oil or reared with the sow. The results suggest that consumption of milk replacer diets containing vegetable oils rich in 18∶3n−3 does not represent a bleeding risk, and that the transient lower platelet count can be counterbalanced by the addition of saturated fatty acids to the vegetable oils.
Rapid determination of double bond configuration and position along the hydrocarbon chain in cyclic fatty acid monomers
Authors: Mossoba M. M. , Yurawecz M. P. , Roach J. A. G. , Lin H. S. , McDonald R. E. , Flickinger B. D. , Perkins E. G. 
Published: December 2006

AbstractThis study reports the structural elucidation of diunsaturated 5‐ or 6‐membered ring cyclic fatty acid monomers (CFAM) isolated from heated flaxseed oil by complementary gas chromatography (GC)‐mass spectrometry (MS) and GC‐matrix isolation‐Fourier transform infrared spectroscopy (MI‐FTIR). Infrared measurements of CFAM were carried out on methyl ester derivatives as well‐resolved chromatograms were obtained on a polar 100% cyanopropyl polysiloxane capillary GC column. By contrast, electron ionization MS of methyl ester derivatives was of limited value because of double bond migration during the ionization process in the mass spectrometer. This communication reports definitive MS fragmentation patterns that can confirm ring position and double bond position along the fatty acid chain in 1,2‐disubstituted CFAM determined as 2‐alkenyl‐4,4‐dimethyloxazoline derivatives. Double bond configuration (cis, trans, or conjugatedcis,cis) in CFAM was confirmed by GC‐MI‐FTIR. The presence of CFAM, degradation products found in used frying oils, is a potential source of dietary toxicity.
UV Spectrophotometry of autoxidized lipid monolayers while on silica gel
Authors: Porter W. L. , Levasseur L. A. , Jeffers J. I. , Henick A. S. 
Published: December 2006

AbstractAutoxidation reactions of linoleic acid and tocopherol and of mixtures of the two have been monitored in the dry monolayer state while adsorbed on silica gel, by means of silica slurry spectrophotometry and oxygen uptake measurements. The UV absorbance of the products of linoleic acid alone is similar to that of previously characterized compounds, but that from tocopherol is not referable to any oxidation products known to the authors, regardless of whether the determination is made while adsorbed on silica or on the extracted products. Two compounds, designated A and B, having absorbance in ethanol at 2610–2670 and 3000 A, respectively, are the major products of tocopherol oxidation detectable by UV above 2200 A. They are a tocopheryl quinone without a hydroxyl group and an adduct of linoleic acid and oxidized tocopherol. The product distribution suggests that tocopherol may have a restricted migration in this system.
Diet and the fatty acids in the plasma of lambs during the first eight days after birth
Authors: Noble R. C. , Steele W. , Moore J. H. 
Published: December 2006

AbstractThis study reports the plasma lipid changes in lambs receiving either ewes' milk or a reconstituted low fat milk powder during the first eight days after birth. The liveweight gains of the lambs on the artificial diet was less than half that observed in the lambs on the natural diet. The plasma lipid levels in the lambs on the natural diet increased considerably after birth due to large increases in the concentrations of the cholesteryl ester, triglyceride and phospholipid fractions. For the lambs on the artificial diet these fractions remained similar to those observed at birth. In both groups unesterified fatty acid fractions decreased after birth. The main difference between the two groups of lambs was the large increase in C18 polyunsaturated fatty acids observed after birth in the lambs on the natural diet. The triene‐tetraene ratio of the fatty acids in the lambs on the natural diet decreased from 1.0 at birth to 0.08 after eight days whereas in the lambs on the artificial diet the ratio increased to 2.9. These composition changes are discussed in relationship to the metabolism of essential fatty acids in monogastric animals.
Determination of plasma tocopherols by gas liquid chromatography
Authors: Lehmann Joanna , Slover Hal T. 
Published: December 2006

AbstractA method is described for the separation and determination of plasma tocopherols by gas liquid chromatography (GLC). Proteins in 0.1 g samples of plasma were precipitated with ethanol containing a known amount of 5,7‐dimethyltocol which served as an internal standard. Tocopherols were extracted into petroleum ether, purified by thin layer chromatography and analyzed as trimethylsilyl ethers by gas liquid chromatography (GLC) on 0.5% Apiezon L. Recoveries of α‐ and γ‐tocopherols averaged 100% and 93%, respectively. The mean total tocopherol content of eight human plasma samples was 8.5 μg/g by GLC and 9.9 μg/g by a ferric chloride‐α,α′‐dipyridyl method. The α‐ and γ‐tocopherol contents of 16 human plasma samples ranged from 4.0 to 12.3 μg/g and 0.6 to 2.1 μg/g, respectively.
Mycobacterial sulfolipids: Spontaneous desulfation
Authors: Goren Mayer B. 
Published: December 2006

AbstractA glycolipid sulfate elaborated in abundance by surface‐grown cultures ofMycobacterium tuberculosis has been characterized in earlier studies as a complex 2,3,6,6′‐tetraacyl α, α′ trehalose 2′‐sulfate. The purified ammonium salt undergoes rapid quantitative desulfation on mere dissolution in reagent grade anhydrous ether. The same reaction is observed in sulfolipids recovered from a number of human strains and one bovine strain. Experimental observations on the normal and acid‐catalyzed rates of the reaction and on the influence of other solvents and other cationic forms support a proposed mechanism, which is detailed. Structural criteria which may influence the proclivity for spontaneous desulfation are discussed.
Lipolysis in castor seeds: A reinvestigation of the neutral lipase
Authors: Ory Robert L. , Angelo Allen J. St. 
Published: December 2006

AbstractAttempts to study the neutral lipase reported in germinating castor seeds and to compare this enzyme to the acid lipase of dormant seeds were unsuccessful because of the inability to repeat the work described earlier (1). Activity of the proposed neutral lipase could not be detected, nor could appearance of the enzyme be hastened or affected by treating the germinating seeds with gibberellic acid or Actinomycin‐D. Possible explanations for the discrepancy between these findings and the early report are presented.
The relationship of milk phospholipids to membranes of the secretory cell
Authors: Patton Stuart , Keenan T. W. 
Published: December 2006

AbstractForty‐two per cent of the lipid phosphorus in milk was found in skim milk lipoprotein; the other 58% occurs in the milk fat globule membrane (MFGM). Investigation of these two sources of lipid phosphorus revealed that they involve the same individual phospholipids, in essentially the same proportions with similar fatty acid compositions. Both contain sphingomyelin and cerebrosides in levels characteristic of those found in plasma membranes. Other points of resemblance between MFGM and skim milk lipoprotein, have been shown previously. Infusion of (14C) palmitate into the mammary gland of a lactating goat produced more extensive labeling of all the phospholipid classes in the skim milk lipoproteins than in those in the MFGM during the following 24 hr. When (14C) palmitate was infused into the jugular vein of a lactating goat, a precusor‐product‐type relationship was observed between specific activities of the skim milk and MFGM polar lipids. These results render the MFGM an unlikely origin of the skim milk lipoprotein. Other possible sources of this latter lipoprotein are Golgi vesicle membranes or plasma membrane of the lactating cell.
Lipid composition and de novo lipid biosynthesis of human palmar fat in Dupuytren's disease
Authors: Rabinowitz Joseph L. , Ostermann Lee , Bora F. W. , Staeffen Jean 
Published: December 2006

AbstractSeventy‐two surgically obtained Dupuytren's disease palmar‐fat (DDPF) specimens and 18 location‐matched speciments from patients not suffering from this disease (controls) were studied for their total lipid composition and de novo lipogenic activity. Incubation of “DDPF” with 1‐[14C]acetate in oxygen produced [14C]palmitate and [14C]stearate in approximately equal yields as those obtained from “controls”. No [14C]octanate was formed in any of the palmar‐fat preparations. The lipids and fatty acid analysis revealed differences; (a) DDPF specimens were richer in free fatty acids, methyl esters of fatty acids and freecholesterol than specimens of controls (b) DDPF specimens contained less phospholipids. (c) DDPF specimens showed a significantly higher content of octanoate and other short‐chain fatty acids than specimens of controls. The above findings are not incompatible with the results expected if some mild hypoxia occurred in DDPF; this has been suggested in the statistical correlations observed for this disease and alcoholism with liver involvement.
The synthesis and biological activity of thiolcarnitine and its thiolesters
Authors: Duhr Edward F. , Mauro J. Matthew , Clennan Edward L. , Barden Roland E. 
Published: December 2006

AbstractAcetyl‐D,L‐thiolcarnitine was synthesized by the acid‐catalyzed addition of thiolacetic acid to 4‐trimethylammonio‐2‐butenoic acid. Acetyl‐D,L‐thiolcarnitine was the precursor of D,L‐thilcarnitine, which was prepared by base hydrolysis. Thiolcarnitine significantly enriched in the L‐isomer was prepared from acetyl‐D,L‐thiolcarnitine using carnitine acetyltransferase as the resolving agent. The C2, C8 and C16 carnitine thiolesters were obtained by acylating thiolcarnitine with the corresponding N‐hydroxysuccinimide esters. As a substrate for carnitine acetyltransferase, acetylthiolcarnitine gave the same kinetic constants as did acetylcarnitine; on the other hand, thiolcarnitine and carnitine gave the same Km but the Vmax with thiolcarnitine was less than 5% of the value obtained with carnitine. With thiolcarnitine and acetylthiolcarnitine as reactants, the measured Keq, at 30 C and pH 7.0, for the reaction catalyzed by carnitine acetyltransferase (see below) was 4.6±.1. acetylthiolcarnitine+CoA—acetyl‐CoA+thiolcarnitine
Preparation of tritium‐labeled sterols and the synthesis of labeled‐24‐azacholesterol
Authors: Thompson Malcolm J. , Berngruber Otto W. , Klein Peter D. 
Published: December 2006

AbstractA method is presented for the preparation of 2,4‐3H‐sterols (stigmasterol, β‐sitosterol, campesterol, fucosterol and 7‐dehydrocholesterol) via the technique of exchange‐labeling of keto steroids and their subsequent conversion to sterols. The preparation of tritium‐labeled 3β‐hydroxy‐24‐norchol‐5‐en‐23‐oic acid and the synthesis of 2,4‐3H‐24‐azacholesterol are reported. Some advantages of the exchange‐labeling method over the conventional catalytic exchange method are discussed.