bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of catecholamines on the distribution of14C‐cholesterol in dogs
Authors: Gans Joseph H. , Cater Marilyn R. 
Published: November 2006

AbstractFifteen adult male pure bred Beagle dogs were given 4‐14C‐cholesterol and a subsequent 18 day period was permitted to elapse for equilibration of the14C‐cholesterol between blood and tissue compartments. Peanut oil, epinephrine in oil or norepinephrine in oil was administered by daily subcutaneous injections over a period of 63 to 81 days. Epinephrine but not norepinephrine resulted in sustained increases in plasma cholesterol concentrations. The half‐life of14C‐cholesterol in plasma was 19 days in control dogs, 18 days in catecholamine treated dogs. The slope of the decline in the specific radioactivity of plasma cholesterol did not change during epinephrine administration, suggesting an influx into plasma of endogenous cholesterol. Specific radioactivity of thoracic aorta cholesterol was fourfold greater than that of plasma cholesterol in control dogs at the end of the experiment and 1.3‐fold greater than the specific radioactivity of cholesterol in the lower aortic segments. Treatment with epinephrine decreased the specific radioactivity cholesterol in all segments of the aorta and resulted in cholesterol specific radioactivity from thoracic aorta which was less than that of cholesterol from the lower aortic segments. Norepinephrine treatment resulted in decreases in the specific radioactivity of cholesterol from the thoracic and abdominal aortic segments but the changes were smaller than those observed in epinephrine treated dogs.
Desaturation of palmitate and stearate by cell‐free fractions from soybean cotyledons
Authors: Inkpen James A. , Quackenbush Forrest W. 
Published: November 2006

AbstractHomogenates of cotyledons from immature soybean seeds were fractionated by centrifugation. Cell‐free preparations actively desaturated 1‐14C‐palmitate and 1‐14C‐stearate to produce 9,10‐unsaturated acids. The 9‐desaturase activity was present mainly in supernatant fractions (22,000 and 105,000 xg). These fractions also desaturated oleate to linoleate and elongated C14, C16 and C18 acids. In view of this versatility of desaturase systems in the soybean, including the 9‐desaturase(s) for C14, C16 and C18 saturated acids, there would not seem to be further need to consider a separate plant pathway for biosynthesis of unsaturated fatty acids.
Composition and biosynthesis of the major hexose containing sphingolipids of pig leucocytes
Authors: Levis Gabriel M. 
Published: November 2006

AbstractThe oligohexosyl ceramides of two preparations of blood leucocytes taken from large white pigs, weighing 80 kg were analyzed and found to comprise as major constituents trihexosyl ceramide, with glucose‐galactose in a molar ratio of 1∶2, and glucosyl ceramide. The mean value of the two preparations was 4.9% and 1.35% of the total lipids, respectively, for the two glycolipids. Lactosyl ceramide is the major component of human leucocytes, in contrast to the pig leucocytes where it was detected in minor quantities. U‐14C‐glucose, incubated with bone marrow cells of young pigs (20 kg living weight), was mainly incorporated into the carbohydrate moiety of glucosyl ceramide and trihexosyl ceramide. Further analysis of this compound indicated that all three hexoses were labeled with14C and that the glucose attached to the ceramide had the highest specific activity. Time studies showed a decline in the incorporation of14C into glucosyl ceramide as compared to its incorporation into trihexosyl ceramide.
A new criterion in the bioassay of essential fatty acids: the spontaneous swelling of rat liver mitochondria in vitro
Authors: Houtsmuller U. M. T. , Van Der Beek A. , Zaalberg J. 
Published: November 2006

AbstractThe spontaneous swelling in vitro of liver mitochondria from rats deficient in essential fatty acids (EFA) and normal rats is compared using the change in optical density as a criterion. Differences between both groups are observed only if high sucrose concentrations are used for the isolation of the mitochondria. The change in optical density can be described mathematically by the sum of two exponential functions. A correlation is found between the parameters of this function and the dose of sunflower seed oil fed to EFA‐deficient rats, which makes the method useful as a criterion in an EFA bioassay. The EFA activities of several synthetic polyunsaturated fatty acids are compared using either growth rate or mitochondrial swelling as a criterion.
Biosynthesis of fatty acids in cell‐free homogenates of lactating gerbil mammary gland
Authors: Coniglio John G. , Bridges Raymond B. 
Published: November 2006

AbstractCell‐free homogenates of lactating mammary gland of gerbils maintained on a diet of sunflower seed, guinea pig chow and oats (Diet 1) or a diet of guinea pig chow and oats (Diet 2) and of rats maintained on laboratory chow (Diet 3) were incubated with14C‐labeled acetate, acetyl CoA or malonyl CoA aerobically. A large proportion of the14C from14C‐acetate and14C‐acetyl CoA incorporated into fatty acids by homogenates from gerbils on Diet 1 was in unsaturated compounds, particularly in 18‐carbon and 20‐carbon dienoic acids, compared to preparations from animals on Diets 2 or 3. The two radioactive dienoic acids were proven to be Δ9,12 18∶2 and Δ11,14 20∶2, and the latter was shown to be a direct elongation product of Δ9,12 18∶2 by the substrate14C‐acetyl CoA. In all experiments14C from14C‐malonyl CoA was incorporated predominantly into 14∶0 and 16∶0, and very little incorporation occurred into unsaturated fatty acids in homogenates made either from gerbil or rat. Total fatty acids isolated from homogenates and from milk fat (fat floating on the centrifuged homogenates) of gerbils on Diet 1 had a higher proportion of 18∶2 than animals on the other two diets, a reflection of the large dietary intake of linoleic acid by gerbils on Diet 1. Under these conditions the amount of 18∶2 in the mammary gland had a significant effect on the products of the incubation.
Peroxidation of microsomal membrane protein—Lipid complexes
Authors: Victoria Edward J. , Barber Albert A. 
Published: November 2006

AbstractNonenzymatic lipid peroxidation was studied using the TBA test on rat liver microsomal fractions, lipid micelles and structural protein‐lipid micelle complexes. The kinetics, response to divalent cations, and iron‐ascorbate catalysis were alike in the microsomal fraction and in the complex, but different in lipid micelles. The structural protein represented 41% of the total membrane protein, had a S20,obs of 3.5 and was hydrophobic. The binding of lipid micelles by structural protein proceeded in two steps, with an initial fast rate followed by a slower rate. The binding appeared to involve a hyrophobic association between lipid and protein as evidenced by insensitivity to pH, ionic strength and lack of preference for the individual classes of phospholipid micelles. Deoxycholate caused an increase in the initial peroxidation rate in microsomal fractions. Iron and ascorbate catalyzed lipid peroxidation in both the microsomal fraction and in the complex. Iron catalyzed lipid peroxidation but calcium, cobalt and copper inhibited the reaction in the SP‐lipid micelle complex. Lipid peroxidation in microsomal suspensions, therefore, appears to be determined, in part, by the hydrophobic nature of the protein‐lipid association found in membranes.
Species variations in phospholipid class distribution of organs: I. Kidney, liver and spleen
Authors: Rouser George , Simon Gerald , Kritchevsky Gene 
Published: November 2006

AbstractImproved procedures for preparation of lipid extracts and determination of phospholipids by phosphorus analysis of spots separated by thin layer chromatography (TLC) were employed to determine the phospholipid class distributions of vertebrate (human, bovine, rat, mouse, frog) kidney, liver and spleen. The absence of significant changes arising from postmortem enzymatic degradation was demonstrated by analysis of lipids of organs after standing for different times postmortem. Intraspecies variability was evaluated by separate analysis of several rat organs. Accuracy of analytical results was insured by demonstrating the absence of spot overlap by two‐dimensional TLC and low values for standard deviations. The values for kidney and liver demonstrate little or no species variability, whereas values for spleen indicate two groups which differ in cellular composition. The findings for kidney and liver are in keeping with data obtained from heart, skeletal muscle, lung and highly purified subcellular particulates which indicate that, among vertebrates, there is little or no species variability of phospholipid class distribution of organs and most subcellular particulates.
A cyanogenetic lipid fromCordia verbenacea DC. Seed oil
Authors: Mikolajczak K. L. , Seigler D. S. , Smith C. R. , Wolff I. A. , Bates R. B. 
Published: November 2006

AbstractCyanogenetic nonglycerol diesters, which are composed of two fatty acid moieties esterified with an unsaturated five‐carbon dihydroxynitrile, constitute 35% ofCordia verbenacea DC. (Boraginaceae) seed oil.
Oxidation of α‐tocopherol to α‐tocopheryl quinone by carbon tetrachloride‐ethanol solvent
Authors: Seward C. R. , Mitchell G. Vaughan , Argrett L. C. , Hove E. L. 
Published: November 2006

AbstractThe addition of small amounts of CCl4 to ethanolic solutions of α‐tocopherol, vitamin A acetate or β‐carotene caused destruction of these fat‐soluble compounds. The oxidation product of α‐tocopherol was identified as α‐tocopheryl quinone by UV and IR spectral analysis. Maximum conversion to the quinone occurred with a ratio of CCl4 to ethanol of 25∶75 (v/v).
Influence of rabbit milk upon cholesterolaemic response of offspring of rabbits
Authors: Roberts D. C. K. , West C. E. 
Published: November 2006

AbstractThe milk lipids from the dams of two strains of rabbits differing in their cholesterolaemic response, one hyperresponsive and one hyporesponsive to dietary cholesterol, were analyzed. The hyperresponsive dams had significantly higher (P<0.05) cholesterol and phospholipid concentrations than the hyporesponsive dams but similar triglyceride concentrations. Cross fostering experiments with hyporesponsive and hyperresponsive offspring were carried out. Offspring from hyporesponsive parents suckled on hyper‐responsive dams resembled hyperresponsive offspring in their cholesterolaemic response. However, offspring from hyper‐responsive parents responded as hyper‐responsive whether they were raised on their natural dams or on foster hyporesponsive dams. We conclude that the trait for hyperresponder characteristics is un‐influenced by rabbit milk, while the trait for hyporesponder characteristics is dependent upon the cholesterol and phospholipid concentrations in milk.
In vitro incorporation of 1‐14C nonanal‐9‐oic acid into plasma and human red blood cells lipids
Authors: Dousset N. , Douste‐Blazy L. 
Published: November 2006

AbstractNonanal‐9‐oic acid is incorporated principally into plasma phospholipids, whereas oleic acid is incorporated into red cells. This incorporation does not require the presence of adenosine 5′‐triphosphate and Coenzyme A and is carried out in the absence of red cells. the incorporation of nonanal‐9‐oic acid in blood lipids takes place in the first 10 min of incubation.
Dibutyryl cyclic adenosine 3′,5‐monophosphate and brain lipid metabolism
Authors: Weiss Benjamin , Stiller Richard L. 
Published: November 2006

AbstractIt was found that dibutyryl cyclic a denosine 3′,5′‐monophosphate exerted its greatest suppressive effect upon total lipid synthesis in 7–10 day old rat bran slices incubated in the presence of 2‐14C‐acetate, U‐14C‐D‐glucose, and 3‐14C‐DL‐serine. Fractionation of the neutral and polar lipids disclosed that the formation of each of their respective components was reduced to varying extents, thus suggesting that cyclic adenosine 3′,5′‐monophosphate, arising from the hydrolysis of dibutyryl cyclic adenosine 3′,5′‐monophosphate, may control the synthesis of brain lipids by regulating the utilization of acetyl‐coenzyme A.
Cholesteryl ester metabolism in tissue culture cells. I. Accumulation in Fu5AH rat hepatoma cells
Authors: Rothblat George H. 
Published: November 2006

AbstractExposure of Fu5AH rat hepatoma tissue culture cells to hyperlipemic rabbit serum results in the accumulation of cellular cholesteryl esters. Accumulation is not a characteristic of all cells in culture, as evidenced by the lack of response of mouse and human fibroblasts. Fu5AH cells grown for 24 hr on 5% hyperlipemic rabbit serum have an 8‐ to 12‐fold increase of cellular cholesteryl esters, small increases in free cholesterol and triglycerides, and no change in phospholipids, when compared to cells grown in normal rabbit serum. Rapid accumulation of cholesteryl esters occurs during the first 8–12 hr of incubation, and maximum cellular concentration is achieved within 24 hr. The maximum level of cellular cholesteryl esters obtained with individual samples of hyperlipemic rabbit serum is correlated with the cholesterol content of the original sera, even when the incubation medium is adjusted to a constant concentration of cholesterol. Heating hyperlipemic rabbit serum (60 C/30 min) does not destroy activity; however, no cholesteryl ester accumulation occurs in heated cells. The stimulatory activity of hyperlipemic rabbit serum primarily is associated with lipoproteins having densities <1.006. High levels of cellular cholesteryl ester are associated with the appearance of cytoplasmic vacuoles containing cholesteryl esters. The increase in cellular cholesteryl esters is accompanied by a decrease of the cholesteryl esters in the growth medium. Cellular cholesteryl esters are not rapidly hydrolyzed or released upon removal of hyperlipemic rabbit serum.
Fatty acids and phospholipids of adult and newborn rat hearts and of cultured, beating neonatal rat myocardial cells
Authors: Rogers C. G. 
Published: November 2006

AbstractFatty acids and phospholipids of adult and newborn rat hearts and of cultured, neonatal rat heart cells were determined by gas liquid and thin layer chromatographies. In adult heart, the proportion of linoleic acid was higher and that of palmitic acid lower than in newborn hearts or in cultured cells. The relative amounts of linoleic and arachidonic acids in adult heart were affected by the source and amount of dietary fat. In heart cells, after 3 days in culture, the proportion of arachidonic acid resembled that in the newborn and adult rat hearts but showed a gradual and significant decline with age. The gradual shift in fatty acid composition as the cells aged in culture was attributed to outgrowth of mesenchymal cells (fibroblasts and endothelioid cells) characterized by a low relative proportion of arachidonic acid. The amounts of phospholipids in heart cells after 3 days in culture differed from those in the newborn or adult rat hearts. Phosphatidylethanolamine was highest in adult heart (34% of lipid phosphorus) and lowest in cells (26%); lecithin was higher in newborn heart (43%) than in adult heart (37%) or in cells (39%), while sphingomyelin was higher in cells (8%) than in newborn (5%) or adult heart (3%). Phospholipid levels in cultured heart cells were unrelated to those of serum in the growth medium. The absence of a significant change in phospholipid composition after continued incubation of the heart cell cultures for periods up to 3 weeks reflected the major structural role of these lipid components in cell membranes.
Positional specificity of adipose tissue lipoprotein lipase
Authors: Nilsson‐Ehle P. , Garfinkel A. S. , Schotz M. C. 
Published: November 2006

AbstractThe positional specificity of preparations of lipoprotein lipase derived from rat epididymal adipose tissue was investigated. The enzyme preparations were a crude extract of acetone powder of the whole tissue, partially purified lipoprotein lipase fractions a and b separated by gel chromatography from such an extract, and lipoprotein lipase activity eluted from adipose tissue into a medium by incubation with heparin in vitro. The enzyme preparations were incubated with triglyceride substrate labeled with3H in the glycerol moiety and with14C in the fatty acid esterified to the 2 position of the glycerol. The reaction products were separated by thin layer chromatography. All preparations preferentially hydrolyzed the 1(3) ester bonds of the tri‐ and diglycerides, indicating that, like lipoprotein lipase from other sources, the adipose tissue enzyme has a specificity for the 1(3) position.
Lipids of six cultivated barley (Hordeum vulgare L.) varieties
Authors: Price Phil B. , Parsons John G. 
Published: November 2006

AbstractThe lipids of representative varieties of 2‐row spring, 6‐row spring, and 6‐row winter‐type barleys were studied. Total barley lipids were classified by silicic acid gel column chromatography and separated by thin layer chromatography, and the fatty acid composition was determined by gas liquid chromatography. Total lipid content of the 6 barley varieties ranged from 3.12%–3.56% (dry wt basis). The average values for neutral lipids, glycolipids, and phospholipids were 71, 9, and 20%, respectively. The fatty acid composition of barley was rather typical of plant tissue. The neutral lipids and glycolipids from all the varieties contained a higher percent of linoleic and linolenic (C 18∶2 and C 18∶3) acids than the phospholipid fraction.
Free and protein‐bound gangliosides in triton X‐100 extracts from rat brain
Authors: Brunngraber Eric G. , Ziboh Vincent A. 
Published: November 2006

AbstractGangliosides that are extracted from brain tissue samples with Triton X‐100 exist in a free form and as a ganglioside‐protein complex. The two forms can be separated by diethylaminoethyl‐cellulose chromatography. Whole brain tissue yields only ganglioside‐protein complexes. Crude mitochondrial and microsomal fractions and synaptosome‐enriched fractions yield both free and protein‐bound gangliosides. The myelin and mitochondria‐enriched fractions yield only free gangliosides. The isolation of ganglioside‐protein complexes and free gangliosides appears to be dependent upon the nature of the starting material.
Lipids of cultured hepatoma cells: III. Triglyceride and phosphoglyceride biosynthesis in minimal deviation hepatoma 7288C
Authors: Wiegand Rex D. , Wood Randall 
Published: November 2006

AbstractMinimal deviation hepatoma 7288 C cells were cultured on media containing 25% serum to the confluent stage. The growth media was replaced with serumfree media containing 1‐14C‐palmitate, and incubations were continued for 0.75, 1.5, 3, 6, 12, and 24 hr. The distribution of radioactivity among the major neutral lipids and phosphoglycerides was determined for cells and culture media. Radioactivity in individual fatty acids of cellular triglyceride, phosphatidylcholine, and phosphatidylethanolamine also was determined. After 24 hr, more than 95% of the administered radioactivity was recovered in neutral and phosphoglycerides, indicating that only a small amount of the fatty acid was oxidized. At any time period examined, over 80% of the incorporated radioactivity was found in triglyceride, phosphatidylcholine, and phosphatidylethanolamine. Incorporation of the label into cellular triglyceride and phosphatidylcholine plateaued at 12 hr, whereas incorporation of radioactivity into phosphatidylethanolamine still was increasing at 24 hr. In contrast, during the entire incubation period the relative distribution of14C among esterified lipid classes in the culture media remained constant. Elongation of palmitic acid to stearic acid and its subsequent desaturation to oleic acid suggests that these cells possess an active elongation and monoenoic desaturation system. Labeled glycerol ether diesters were not detected in the cells or culture media. Positional distribution of the14C label in the triglyceride and phosphatidylcholine suggests that minimal deviation hepatoma cells do not exhibit diglyceride selectivity in the biosynthesis of these two lipid classes.
Staphylococcal lipases
Authors: Vadehra D. V. 
Published: November 2006

AbstractA lipase rich fraction was isolated from the cell free supernatant of 24 hr broth culture ofStaphylococcus aureus B‐120, grown in trypticase soy broth at 37 C. Lipase from the cell free supernatant was precipitated with equal volumes of absolute ethanol. This fraction was purified further by differential precipitation at pH 8.6 and 4.3. Subsequent purification, using Sephadex G‐200 and BioGel 300, yielded a preparation with 350–450‐fold increase in specific activity. The purified lipase had an optimum pH of 8.5 at 37 C. The electrophoretic mobility was‐7.78×10−5 cm2/volt/sec. The sedimentation coefficient for the two peaks was 2.85 and 8.5, respectively, and the mol wt was 100,000. The purified lipase hydrolyzed a variety of natural oils and fats. The amount of free fatty acids liberated from hydrogenated soybean oil (iodine value<3) was one‐third compared to natural oils and fats. Gas chromatographic analysis of hydrolyzed synthetic triglyceride, with palmitic, stearic, and oleic acids at the rac 1, 2, and 3 positions, respectively, indicated that the enzyme was capable of hydrolyzing the glycerolfatty acid bonds at all three positions. The yield was 40% palmitic, 20% stearic, and 39% oleic acids. Formaldehyde, mercaptoethanol, cysteine, glutathione, and terramycin had inhibitory effects upon lipase activity while hydrogen peroxide, streptomycin, and sodium taurocholate had a stimulatory effect upon the activity.
Some properties of an exocellular lipase fromRhizopus arrhizus
Authors: Benzonana Gilbert 
Published: November 2006

AbstractRhizopus arrhizus, a mold of the mucor family, excretes an active lipase when cultured properly. This lipase has a mol wt of 43,000 and a high carbohydrate content, Upon storage at 4C in aqueous solution, lipase I is slowly converted by proteolysis to a more cationic form, lipase II, which has a lower mol wt (32,000) and no carbohydrate.Rhizopus lipase shows the same positional specificity on long chain triglycerides as pancreatic lipase; it has no preferential side chain specificity against oleic vs. palmitic acid. Like pancreatic lipase,Rhizopus lipase acts on micelles of short chain triglycerides and is inhibited by high concentrations of bile acids; however, in the presence of deoxycholate,Rhizopus lipase does not require added Ca++ for full activity.