bluuebunny/crossref_metadata_2025_split huggingface dataset:
Positional distribution of fatty acids in the triglycerides of bovine milk fat with elevated levels of linoleic acid
Authors: Morrison I. M. , Hawke J. C. 
Published: November 2006

AbstractA stereospecific distribution of fatty acids in bovine milk fat containing 15.5% linoleic acid has been compared with the distribution in bovine milk fat containing a normal level (1.8%) of linoleic acid. The positional distribution was obtained by the separate analysis of milk fat triglycerides of high, medium, and low molecular weight. The order of preference for linoleic acid in the high molecular weight triglycerides was position 3>position 2 >position 1. There was an accompanying altered distribution of myristic acid and palmitic acid in favor of position 1 at the expense of position 3. However, the proportions of myristic acid and palmitic acid in position 2, relative to positions 1 and 3 were identifical in the high molecular weight fractions of the two milk fats. The distribution of linoleic acid in the medium molecular weight triglycrides of linoleic‐rich milk fat was position 1=position 2>position 3. This resulted in a change in the distribution of 18 carbon monounsaturated fatty acids in favor of position 2 at the expense of position 1, but the distribution of myristic acid and palmitic acid was virtually unaltered. The distribution of linoleic acid in the low molecular weight triglycerides was position 2>position 1>position 3. The amounts of myristic acid and palmitic acid in position 2 and of palmitic acid in position 1 decreased in the low molecular weight triglycerides of the milk fat containing elevated levels of linoleic acid. Changes in the distribution of fatty acids which were observed in the separate analysis of the high, medium, and low molecular weight triglycerides were not apparent when comparing the distribution in the total milk fats. For example, the distribution of myristic acid and palmitic acid appeared to be unchanged, while the distribution of 18 carbon monounsaturated fatty acids was slightly altered in favor of positions 2 and 3. Moreover, linoleic acid showed an almost equal preference for the three positions of the glycerol moiety in milk fat containing elevated levels of this fatty acid with some concentration at position 2.
The dietary regulation of stearyl coenzyme A desaturase activity and membrane fluidity in the rat aorta
Authors: Holloway Caroline T. , Holloway P. W. 
Published: November 2006

AbstractNumerous studies have demonstrated that alterations in membrane composition or fluidity are often associated with alterations in the properties of membrane‐bound enzymes. In order to obtain membranes of varying fluidity, rats were fed diets that were either fat‐free or supplemented with 15% safflower oil, and two properties associated with aorta and liver microsomal membranes were selected for study: stearyl CoA desaturase activity, and fluidity as monitored by fatty acid composition and microviscosity (measured by fluorescence depolarization). If fluidity directly modulates desaturase activity, one would predict that a low fluidity would stimulate the desaturase activity. Ten times more desaturase activity is present in aorta microsomes from rats on a fat‐free diet than in microsomes from rats on a safflower oil supplemented diet. However, on the fat‐free diet, these aorta microsomes were more fluid than those of rats fed safflower oil supplemented diet. The fluidity of liver microsomal membranes was not altered in response to diet, despite significant changes in desaturase enzyme content. The contrasting evidence presented here suggests that no correlation exists between desaturase enzyme activity and membrane fluidity in the two tissues studies. We have demonstrated that the aorta has appreciable capacity to desaturate stearyl CoA and that dietary manipulation causes significant changes in aorta membrane fluidity that may be of sufficient magnitude to affect the overall metabolism of aorta cells.
Analysis of autoxidized fats by gas chromatography‐mass spectrometry: III. Methyl linolenate
Authors: Frankel E. N. , Neff W. E. , Rohwedder W. K. , Khambay B. P. S. , Garwood R. F. , Weedon B. C. L. 
Published: November 2006

AbstractThe gas chromatography‐mass spectrometry (GC‐MS) method developed in the preceding papers was extended to the analysis of autoxidation products of methyl linolenate. Four isomeric hydroxy allylic trienes with a conjugated diene system were identified after reduction of the linolenate hydroperoxides. All eight geometrictrans,cis‐ andtrans, trans‐conjugated diene isomers of these hydroxy allylic compounds were identified and partially separated by GC of the trimethylsilyl (TMS) ether derivatives. The proportion found of 9‐ and 16‐hydroperoxides was significantly higher (75–81%) than the 12‐ and 13‐hydroperoxides (18–25%). The tendency of the 12‐ and 13‐hydroperoxides to form cyclic peroxides, cyclic peroxidehydroperoxides, and prostaglandin‐like endoperoxides was supported by indirect evidence for the presence of 9,10,12‐ and 13,15,16‐trihydroxyoctadecanoate in hydrogenated derivatives of the highly oxygenated products. The quantitative GC‐MS method was used to determine the relative contribution of linolenate, linoleate, and oleate in mixtures to the formation of hydroperoxides.
Lipids of cultured hepatoma cells: VIII. Utilization of D‐[1‐14C] glucose for lipid biosynthesis
Authors: Welch Charles L. , Wood Randall 
Published: November 2006

AbstractMinimal deviation hepatoma 7288C cells (HTC) were incubated in serum‐supplemented and serum‐free Swim's 77 medium in the presence of D‐[1‐14C] glucose for 1, 2, 4, 8, 12 and 24 hr. Glucose oxidation to CO2, incorporation into total cell mass, and incorporation into cell and medium lipids were determined. The percentage distribution of total cell lipid radioactivity in individual neutral and polar lipid classes was followed as a function of time. Degradation studies of individual lipid classes were performed to ascertain the percentage of radioactivity in acyl and glycerol moieties. The percentage of D‐[1‐14C] glucose oxidized to14CO2, incorporated into cell matter and cell lipids was elevated in cells incubated in serum‐free medium as opposed to serum‐supplemented medium. The percentage distribution of total cell lipid radioactivity into individual neutral lipid classes from both serum‐free and serum‐supplemented cultures was as follows: sterols > triglycerides > free fatty acids > sterol esters. The percentage distribution of total cell lipid radioactivity into individual polar lipid classes of serum‐supplemented cultures was as follows: phosphatidylcholine > phosphatidylinositol > sphingomyelin > phosphatidylethanolamine > phosphatidylserine. The distribution of glucose radiolabel into individual polar lipid classes of serum‐free HTC cells was different from their serum‐supplemented counterparts: sphingomyelin > phosphatidylcholine > phosphatidylinositol > phosphatidylethanolamine > phosphatidylserine. Glycerol from glyceride classes contained a higher percentage of radioactivity than the acyl moieties, with this percentage significantly elevated in serum‐free cultures. The data indicate that, although glucose is a substrate for HTC cell lipids, other precursors present in the culture system also contribute to the lipid constituency of this hepatoma cell line.
The effect of a short term saturated fat diet on the apoprotein composition and radioiodination properties of rat very low density lipoproteins
Authors: Poulis Parissa , Fidge Noel H. 
Published: November 2006

AbstractThe effect of a saturated fat diet on the apoprotein composition and radioiodination properties of plasma very low density lipoprotein (VLDL) was studied in rats. After feeding the diet for 10 days, the proportion of125I attached to VLDL lipid decreased from 50% (control animals) to 8%, the remainder (92%) being bound to the apoportein components. The decreased lipid labelling was associated with proportional changes in the fatty acid composition of serum and VLDL lipids, the most notable change being a reduction in linoleic acid (30–8%) content which occurred in all the major lipid classes of both serum and VLDL. Analysis of VLDL after radioiodination showed that most of the radioactivity incorporated into the lipid moiety was associated with phospholipid. The proportion of125I bound to phospholipid decreased after feeding rats a saturated diet. The proportion of soluble (small molecular weight peptides and arginine rich peptide) to insoluble (B apoprotein) did not alter during the saturated fatty acid dietary regime and no differences in the distribution of soluble proteins were observed. It is concluded that feeding a saturated fat diet to rats for 10 days significantly improved125I labelling of the apoprotein moiety while apparently not inducing changes in apoprotein composition.
Synthesis of a monobrominated analog of dipalmitoyl lecithin
Authors: Reinert J. C. , Lowry R. R. , Wickman H. H. 
Published: November 2006

AbstractThe synthesis of 1‐palmitoyl‐2‐monobromopalmitoyl lecithin, where the β‐chain is brominated in either the 9‐ or 10‐position, is reported, Monobromopalmitic acid was prepared by addition of HBr to palmitoleic acid, and the anhydride of the fatty acid conjugated with 1‐palmitoyl lysolecithin. The resulting lecithin was isolated by preparative thin layer chromatography and its structure confirmed by chemical and enzymatic analysis.
Diester waxes from skin lipids of the feet of biotin depleted and biotin supplemented Turkey poults
Authors: Logani Mahendra K. , Nhari David B. , Forbes P. Donald , Davies Ronald E. 
Published: November 2006

AbstractThe neutral lipids of the skin from the feet of turkey poults fed a biotin supplemented or a biotin deficient diet consist mainly of triacylglycerols, and of mono‐ and diester waxes. Diester waxes from both groups were characterized as fatty acid esters oferythro‐2,3‐alkanediols. A comparison between fatty acid composition of the two groups, however, revealed the following significant differences. Biotin deficient birds showed a fairly high concentration of very long chain fatty acids (C36–C40) which were completely absent in biotin supplemented birds. Further, almost one‐third of the fatty acids of diester waxes in biotin deficient birds were unsaturated while those from biotin supplemented birds were predominantly (96%) saturated.
Equilibrium of taurodeoxycholate between mixed micellar and aqueous phases: Effect of amphiphile
Authors: Borgström B. 
Published: November 2006

AbstractThe equilibration of taurodeoxycholate between mixed micellar and aqueous phases has been studied by equilibrium dialysis. The presence of amphiphiles in the form of lecithin, long chain monoglyceride, and fatty acid in the bile salt solution will greatly decrease the bile salt concentration in the aqueous (intermicellar) phase. At high amphiphile concentration relative to bile salt, the concentration of bile salt in the aqueous phase will be below the critical micellar concentration (CMC) of the pure bile salt solution. Under these conditions, few simple micelles will be present and no binding of bile salts to protein takes place as indicated by experiments with colipase. The lowering of the concentration of bile salt in the aqueous phase by the presence of amphiphile may be a physiological mechanism to regulate bile salt absorption during the digestive phase of fat absorption.
Protective effect of biliary lipids on rat pancreatic lipase and colipase
Authors: Lairon D. , Nalbone G. , Lafont H. , Domingo N. , Hauton J. C. 
Published: November 2006

AbstractThe effect of biliary components on the inactivation of rat pancreatic lipase and colipase was studied. In vitro incubations of these proteins were performed at 37 C in the presence or absence of trypsin, under various conditions. The influences of bile lipoprotein complex, bile salts below or above the critical micellar concentration (CMC), or albumin were investigated. The results showed that albumin and bile salts below the CMC had no protective effect on the inactivation rate of lipase or colipase. Under both denaturating conditions, bile salts above the CMC had a very slight effect, whereas the presence of the bile lipoprotein complex maintained lipase and colipase activity. The magnitude of this effect was related to the biliary phospholipid concentration. By means of gel filtration, the protective effect of bile was found to be due to associations of bile lipoprotein complex with these proteins in presence of bile salts. A correlation between the amount of colipase and the protection of lipase in the presence of biliary phospholipids was observed. Intestinal content of rats with normal and diverted bile secretion was submitted to the same in vitro incubation, and the enzyme was more stable in the segments containing biliary phospholipids. This suggests that the interaction between the bile lipoprotein complex, colipase and lipase in the presence of bile salts could have an important role in the intestinal lumen by retaining the enzyme activity.
Lipid accumulation in cells derived from porcine aorta and grown under anaerobic conditions
Authors: Briggs Robert G. , Glenn Joseph L. 
Published: November 2006

AbstractFibroblast‐like cells, derived from porcine aorta, were cultured under aerobic and anaerobic conditions. Light and electron microscopic examinations, lipid composition measurements, and incorporation of radioactive precursors into lipids of these cells were performed. Anaerobically grown cells accumulated oil red 0 stainable droplets and within 6 hr the triacylglycerol content increased to 4 times the level determined in cells grown under aerobic conditions. This ratio remained constant throughout an additional 12 hr of growth. The fatty acid composition of the triacylglycerols which accumulated under anaerobic conditions differed from the composition of fatty acids in the triacylglycerols present in the growth medium. The cellular unesterified fatty acids of the anaerobically grown cells differed only slightly in composition from the fatty acids in the growth medium, while the unesterified fatty acids of aerobically grown cells differed to a greater extent from those of the growth medium.
Fatty acid metabolism in the calanoid copepodParacalanus parvus: 1. Polyunsaturated fatty acids
Authors: Moreno Victor J. , De Moreno Julia E. A. , Brenner Rodolfo R. 
Published: November 2006

AbstractThe metabolic fate of radioactive linoleate and α‐linolenate administered to the South Atlantic copepodParacalanus parvus was studied. The wild copepod was able to incorporate the labeled acids dissolved in seawater. The radioactive linoleate was elongated to 20∶2ω6 and 22∶2ω6 and desaturated by a Δ6 desaturase to 18∶3ω6. α‐Linolenate was also desaturated by a Δ6 desaturase to 18∶4ω3 and elongated to 20∶3ω3. The copepod was able to convert α‐18∶3 to 20∶5ω3 and 22∶6ω3.
Cholesterol metabolism in the liver and intestine of the chick: Effect of dietary cholesterol, taurocholic acid and cholestyramine
Authors: Sklan D. , Budowski P. 
Published: November 2006

AbstractThe effect of feeding cholesterol, taurocholic acid, or cholestyramine to chicks on cholesterolgenesis from [1‐14C] acetate in liver and intestine was determined in vitro using tissue slices, and in vivo by i.v. injection of [14C] acetate. The conversion of cholesterol to bile acids in liver in vivo was measured in the same treatments after i.v. injection of [3H] cholesterol. Hepatic cholesterogenesis in vitro and in vivo was depressed by dietary cholesterol and taurocholate and enhanced by cholestyramine. Intestinal cholesterogenesis in vivo was depressed only by taurocholate whereas ileal cholesterogenesis in vitro was reduced by dietary cholesterol. Conversion of cholesterol to bile acids was enhanced by dietary cholesterol and cholestyramine and depressed by taurocholate. Hepatic cholesterol metabolism in the chick appears to be regulated by mechanisms similar to those reported for other species.
The effect of exercise on plasma high density lipoproteins
Authors: Wood Peter D. , Haskell William L. 
Published: November 2006

AbstractThe influence of vigorous activity in man on plasma lipids and lipoproteins is reviewed, with particular emphasis on high density lipoproteins. Both cross sectional and longitudinal (or training) studies have been reported, many of them of less than ideal design. Nonetheless, a consistent pattern emerges in which increased exercise levels lead to lower plasma concentrations of triglycerides and very low density lipoproteins, and of low density lipoproteins. High density lipoprotein levels increase. Sometimes, but not uniformly, plasma total cholesterol level falls as the result of these changes. The increase in plasma high density lipoprotein appears to be the result largely of an increase in the less dense HDL2 subfraction. Plasma apolipoprotein A‐I levels (but not apo‐A‐II levels) seem to increase concomitantly. The precise biochemical mechanism responsible for these changes has not been elucidated; but the recent finding of increased lipoprotein lipase activity in adipose tissue and muscle of endurance runners suggests that increased lipolytic rate of trigly ceride‐rich lipoproteins may be an initial step in a sequence of events leading to higher plasma levels of HDL2.
Studies on biosynthesis of waxes by developing jojoba seed. II. the demonstration of wax biosynthesis by cell‐free homogenates
Authors: Pollard Michael R. , McKeon Tom , Gupta Lata M. , Stumpf P. K. 
Published: November 2006

AbstractThe following enzyme activities were demonstrated in cell‐free homogenates from developing jojoba cotyledons: 1) elongation of long chain acyl‐CoAs in the presence of malonyl‐CoA and NADPH (or NADH), 2) NADPH‐dependent reduction of long chain acyl‐CoAs to the corresponding alcohols, 3) esterification of long chain acyl‐CoAs and the alcohols produced from them into wax, 4) elongation of stearoyl‐ACP to eicosanoate and docosanoate as well as reduction to stearyl alcohol, 5) desaturation of stearoyl‐ACP to oleate in the presence of reduced ferredoxin, and 6) incorporation of malonyl‐CoA into long chain fatty acids and alcohols in the presence of added acyl carrier protein. These activities were associated entirely with the floating wax pad after centrifugation of the cell‐free homogenate at 12,000 g for 20 min. The relevance of the above reactions (1–6) to wax biosynthesis in vivo is discussed. Production of oleate from acetate by enzymes utilizing ACP‐thioesters as substrates followed by conversion of oleyl‐ACP to oleoyl‐CoA (via free oleic acid) for subsequent elongation, reduction, and esterification, is presented as the most probable in vivo pathway, for wax biosynthesis. The substrate specificities of the elongation and reduction reactions utilizing acyl‐CoAs as substrates are examined in terms of wax composition.
Studies on cell proliferation in inguinal adipose tissue during early development in the rat
Authors: Gaben‐Cogneville A. M. , Swierczewski E. 
Published: November 2006

Abstract[2‐14C] Thymidine was injected into rats aged 3, 5 and 10 days, and incorporation of the precursor into deoxyribonucleic acid (DNA) of the inguinal fat tissue was measured for short time periods. Using chromatographic procedures to measure the distribution of thymidine and its metabolites in the soluble fraction of the tissue, degradation of the precursor was found to be similar at all ages. The data indicate that thymidine was more rapidly utilized for DNA synthesis in 3‐day‐old rats than in older animals. When14C‐thymidine was injected in vivo and adipocytes and stromal cells were then separated from the inguinal tissue of 3‐and 5‐day‐old rats, the incorporation into DNA was significant in both types of cells already 30 min after pulse labeling. Stromal cells took up twice as much of label as the adipocytes. Furthermore, real incorporation into DNA was found in the adipocytes when incubated in vitro in a culture medium supplemented with14C‐thymidine. The possibility is discussed that early in postnatal life adipocytes might synthesize DNA for further cell division.
Preparation of cupric palmitate membrane, its characterization and evaluation of thermodynamically effective fixed charge density
Authors: Nasim Beg M. , Siddiqi Fasih A. , Husain Akmal , Islam Badrul 
Published: November 2006

AbstractMembrane potentials have been measured across, parchment‐supported cupric palmitate membrane separating various 1∶1 electrolytes at concentrations C1 and C2 such that C2=10 C1. Membrane potential data have been used to calculate transference number of ions, permselectivity and also to derive the thermodynamically effective fixed charge density which is an important characteristic governing the membrane phenomena, by utilizing the generally accepted and most widely used theory of Teorell‐Meyer and Sievers as well as the recent theories for membrane potential of Kobatake et al. and Nagasawa et al. based on the principles of nonequilibrium thermodynamics. The values of charge densities derived from different theories were almost the same, confirming thereby the validity of the recently developed theories of membrane potential.
Biliary cholesterol absorption in normal and L‐thyroxin‐fed rats
Authors: Lutton C. , Brot‐Laroche E. 
Published: November 2006

AbstractInfusion of bile containing labeled cholesterol into bile fistula rats has permitted an in vivo study of the movements and of the absorption of biliary cholesterol in the digestive tract. The specific activities of cholesterol were similar in the micelles and the sediment of the luminal content after a 6 hr infusion, indicating rapid exchange of cholesterol between these fractions. In animals fed a basal diet, the biliary cholesterol absorption was higher (83%) than that of dietary cholesterol (70%). Bile cholesterol is essentially absorbed in the jejunum while the absorption of cholesterol from the diet takes place all along the small intestine but preferentially in its second and third quarters. Both alimentary cholesterol and bile cholesterol enter the top cells of the villi in preference to those of the crypts. In L‐thyroxin‐fed rats, a parallel decrease in biliary and dietary cholesterol absorption was observed. The increase in the intestinal transit of cholesterol and epithelium cell renewal of the jejunum accounted for this observation.
De novo fatty acid synthesis and fatty acid elongation catalyzed by subcellular fractions from hog and human aorta
Authors: Slakey Linda L. , Ferrick Thomas J. , Ness Gene C. , Porter John W. 
Published: November 2006

AbstractDe novo synthesis and mitochondrial elongation of fatty acids have been demonstrated in subcellular fractions from hog and human aorta. Microsomal fatty acid elongation has been shown in hog aorta. The activity catalyzing the formation of fatty acids from acetyl and malonyl CoA was associated with a high molecular weight complex in the 6×106g×min supernatant fraction. The principal product was palmitic acid. Some myristic and stearic acids were also formed. One elongation system was associated with protein which sedimented between 4500 g×min and 150,000 g×min. It used acetyl CoA but not malonyl CoA, and NADH was the preferred reducing agent. Radioactivity from acetyl CoA was incorporated into many fatty acids. In hog aorta a second elongation system was found associated with protein which sedimented at 6×106 g×min. It used malonyl CoA preferentially as substrate and either NADH or NADPH as reducing agent.