bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of the Iatroscan TH‐10 analyzer to quantify total lipids in a variety of sample types and lipid classes in human gallbladder bile
Authors: Harvey H. Rodger , Rigler Mark W. , Patton John S. 
Published: November 2006

AbstractTwo methods for the measurement of total lipid weight in biological and geological samples and the major lipid classes in human gallbladder bile using the Iatroscan TH‐10 analyzer are described. Total lipid determination involves the application of small (5 μl) volumes to Chromarods, focusing of the sample into one band by partial development in chloroform‐methanol (1∶1), and quantification by flame ionization detection (FID). The response variation between different sample types did not affect the linearity of response, allowing a reproducibility of ±10% of the mean or better for samples ranging from 0.5 to 32 μg. Total lipid determinations in 10 samples could be performed in 30 min. The three major components of human gallbladder bile (cholesterol, phospholipids and bile acids) also were quantified with the Iatroscan. Samples focused on Chromarods were separated using a double development scheme in two solvent systems. All three components exhibited a linear response over the range of 0.25 to 8 μg. The repeated scanning of rods required at concentrations greater than 3 μg did not affect linearity of response. Samples from 10 patients could be processed in less than one hr. Several techniques are discussed to increase reproducibility when performing quantitative lipid analysis with the Iatroscan.
Quantitative determination of lipids and their constituents by the Chromarod TLC‐FID system
Authors: Itoh Toshihiro , Tanaka Masamichi , Kaneko Hiroshi 
Published: November 2006

AbstractThe methanolysis products of neutral sphingolipid and archaebacterial neutral glycolipid were separated on Chromarods S‐II (silica gel) with a double developing system. The lipid constituents separated on the rods were scanned automatically with a hydrogen flame ionization detector (Iatroscan). The molar ratios of the constituents determined by this system were very close to the theoretical values of the lipid.
Quantitative analyses of methyl esters of fatty acid geometrical isomers, and of triglycerides differing in unsaturation, by the Iatroscan TLC/FID technique using AgNO3 impregnated rods
Authors: Sebedio J. L. , Farquharson T. E. , Ackman R. G. 
Published: November 2006

AbstractThe relative FID responses for Iatroscan analyses ofcis andtrans isomers of methyl esters of 18∶1†6, 18∶1†9 and 18∶1†11 on Chromarods‐S impregnated with AgNO3 were studied at load levels ranging from 0.5 to 20 μg, using methyl stearate as internal standard. The FID response correction factors were greater for thecis than for thetrans isomers. The correction factors were relatively constant in the 10–20 μg interval, but increased in the range 0.5–5 μg.Separation of tristearin, triolein, trilinolein and trilinolenin also was obtained on Chromarods‐S impregnated with AgNO3 using a mixture of benzene: chloroform: acetic acid (90∶8∶2) as the solvent system. The relative FID responses for the triolein, trilinolein and trilinolenin were determined at load levels ranging from 0.5 to 14.3 μg using tristearin as an internal standard. The FID response correction factors of these three triglycerides differed significantly for load levels of 1.0, 2.5 and 5.0 μg. However, the factors could be considered as being equal in the range 10 to 14.3 μg.Correction factors were not affected by repeated re‐use of the same set of Chromarods. Several hundred separations and scans appeared feasible.
Effect of high fat/high erucic acid diet on phosphatidate synthesis and phosphatidate phosphatase in the subcellular fractions of rat heart and liver
Authors: Kako K. J. , Peckett S. D. 
Published: November 2006

AbstractRats of weaning age were fed for a period of 1,3 or 6 weeks either a control diet (laboratory stock diet) or a semisynthetic diet containing 20% by weight of either mustard seed oil (1/3 of the total fatty acids were comprised of erucic acid) or corn oil (2/3 of the total fatty acids consisted of linoleic acid). Mitochondrial and microsomal fractions were isolated from the hearts and livers of these rats, and the rate of acylation ofsn‐[U‐14C] glycerol 3‐phosphate (P) was examined using palmitoyl‐CoA or erucoyl‐CoA as the acyl donor. In addition, activities of phosphatidate phosphatase of the mitochondrial, microsomal and soluble fractions were assayed. Studies on the acylation of glycerol 3‐P with palmitoyl‐CoA demonstrated that feeding of the high fat/high erucic acid diet for 1,3 or 6 weeks significantly increased the rate of formation of monoacylglycerol 3‐P by the cardiac subcellular fractions as compared to the control. The rate of formation of diacylglycerol 3‐P also increased but to a lesser degree. Feeding the high fat/high linoleic acid diet tended to increase acylation of glycerol 3‐P by cardiac subcellular fractions. However, neither high fat diet influenced acyltransferase activities of the hepatic subcellular fractions or phosphatase activities of the cardiac and hepatic fractions. Studies on the acylation of glycerol 3‐P with erucoyl‐CoA demonstrated that the rate of acylation was ca. 1/10 that measured using palmitoyl‐CoA in all experiments; in particular, the formation of diacylglycerol 3‐P was extremely slow, suggesting that erucoyl‐CoA is an unsuitable substrate for the position‐2 of the monoacylglycerol 3‐P. The rate of acylation by the cardiac and hepatic subcellular fractions was not influenced by the feeding of the high‐fat diets. The rate of glycerol 3‐P acylation by both cardiac and hepatic mitochondrial fraction was ca. 2/3 of the rate of acylation by the respective microsomal fraction. In addition, the ratio of monoacyl‐to diacylglycerol 3‐P synthesized by the mitochondrial fraction was smaller than that by the microsomal fraction. These results suggest that acylation of glycerol 3‐P by the mitochondrial cannot be attributed to the action of the contaminating microsomal enzymes.
The metabolism of 18∶0 and 18∶2(n−6) by the ovine placenta at 120 and 150 days of gestation
Authors: Shand J. H. , Noble R. C. 
Published: November 2006

AbstractThe effects of the approach of parturition in the, sheep on the incorporation of 18∶0 and 18∶2(n−6) into the placental lipids and on the activities of the Δ9‐ and Δ6‐desaturase enzymes of placental tissue have been studied in vitro. The incorporation of 18∶0 into the esterified lipids of placental tissue between the 120th and 150th days of gestation declined markedly; the high level of incorporation of 18∶2(n−6) into the esterified lipids of the placenta (some 2‐fold higher than18∶0) remained constant over the gestational period. While placental Δ9‐desaturase activity was the same at 150 days as at 120 days of gestation, the activity of the Δ6‐desaturase enzyme increased significantly. These results are discussed in relation to the fetal demand for fatty acids near term and the differences that exist between the mechanisms of maternal‐fetal transfer of 18∶0 and 18∶2(n−6) in the sheep.
Phase transition of an unnatural analog of phosphatidylcholine: Phosphatidyl‐N‐isopropylethanolamine
Authors: Lee Ten‐Ching , Snyder Fred 
Published: November 2006

AbstractThe phase‐transition temperature, of an aqueous dispersion of dipalmitoyl phosphatidyl‐N‐isopropylethanolamine was determined was determined usingtrans‐parinaric acid as a fluorescent probe. Phosphatidyl‐N‐isopropylethanolamine has a phase‐transition temperature that is 3–4 C higher than the corresponding natural analog of dipalmitoyl phosphatidylcholine.
Increased proportion of medium chain fatty acids in nystatin‐resistant yeast mutants
Authors: Nagai J. , Yokoe S. , Tanaka M. , Hibasami H. , Ikeda T. 
Published: November 2006

AbstractFatty acid composition of phospholipids and steryl esters from four nystatin‐resistant mutants ofSaccharomyces cerevisiae was compared to that from the wild strain. All the mutant strains which produce several ergosterol intermediates incorporated two‐to three‐fold as much medium chain fatty acids, especially 14:0 and 14:1 in phospholipids, and 12:0, 14:0 and 14:1 in steryl esters as the wild strain did. The increase in the relative amount of medium chain fatty acids in these mutants was found at all the growth temperatures and the growth phases examined, and in all the phospholipid species.
Alteration of cholesterol metabolism by 4‐0‐methylascochlorin in rats
Authors: Hosokawa Tomoyoshi , Sawada Mikio , Ando Kunio , Tamura Gakuzo 
Published: November 2006

AbstractThe effect of 4‐0‐methylascochlorin (MAC), an experimental hypocholesterolemic agent, on cholesterol metabolism was investigated in rats in two separate experiments. The administration of MAC for 2 and 6 consecutive weeks at daily doses of 100–135 mg/kg resulted in reduction in serum cholesterol levels of 16% after 2 weeks of treatment in the first experiment, and 13% after 6 weeks in the second experiment in comparison to the corresponding controls. MAC administered at a daily dose of 100 mg/kg for 2 weeks showed a significant increase in the biliary excretion of bile acids and cholesterol in bile‐duct cannulated rats with or without the administration of taurocholate. In the second experiment, MAC treatment for 6 weeks produced a marked increase in the fecal output of acidic sterols during a 2 to 6‐week period. MAC treatment also further enhanced hepatic cholesterol 7α‐hydroxylase in the rats. Therefore, it appears that the mechanism of serum cholesterol lowering due to MAC is related to the enhancement of hepatic bile acid synthesis and the increase in biliary and fecal excretion of bile acids.
High pressure liquid chromatography of autoxidized lipids: II. Hydroperoxy‐cyclic peroxides and other secondary products from methyl linolenate
Authors: Neff W. E. , Frankel E. N. , Weisleder D. 
Published: November 2006

AbstractA previous study of autoxidation products by high pressure liquid chromatography (HPLC) of methyl oleate and linoleate was extended to methyl linolenate. Autoxidized methyl linolenate was fractionated by HPLC either after reduction to allylic alcohols on a reverse phase system, or directly on a micro silica column. Isolated oxidation products were characterized by thin layer and gas liquid chromatography and by ultraviolet, infrared, nuclear magnetic resonance and mass spectrometry. Secondary products from the autoxidation mixtures (containing 3.5–8.5% monohydroperoxides) included epoxy unsaturated compounds (0.2–0.3%), hydroxy or hydroperoxy‐cyclic peroxides (3.8–7.7%), epoxy‐hydroxy dienes (<0.1%), dihydroxy or dihydroperoxides with conjugated diene‐triene and conjugated triene systems (0.9–2.9%). Cyclization of the 12‐ and 13‐hydroperoxides of linolenate would account for their lower relative concentration than the 9‐ and 16‐hydroperoxides. Dihydroperoxides may be derived from the 9‐ and 16‐linolenate hydroperoxides. Cyclic peroxides and dihydroperoxides are suggested as important flavor precursors in oxidized fats.
Zinc deficiency‐induced changes in the composition of microsomal membranes and in the enzymatic regulation of glycerolipid synthesis
Authors: Clejan Sanda , Maddaiah V. T. , Castro‐Magana M. , Collipp P. J. 
Published: November 2006

AbstractThe effects of zinc deficiency and/or castration on the lipid composition of microsomal membranes of liver, small intestine and testes were studied in rats. The results showed that feeding a zinc‐deficient diet to castrated rats decreased phospholipid content and consequently increased the cholesterol‐to‐phospholipid ratio in liver microsomes. An increase in cholesterol‐to‐phospholipid ratio occurred also in small intestine and testes microsomes from rats fed the zinc‐deficient diet. It is postulated, therefore, that zinc deficiency alters the lipid composition and fluidity of microsomal membranes. Zinc deficiency also affected the activities of the enzymes involved in the formation of triglycerides and phospholipids. There was a large increase in total and specific activity of phosphatidate phosphatase and the changes in the total activity of choline phosphotransferase correlated well with the changes observed in serum or liver triglycerides and phospholipids. Stearoyl CoA desaturase, which is a control enzyme for hepatic lipogenesis, was also increased by more than 200% in zinc‐deficient states, as was the diglyceride content of hepatic microsomes. These results indicate that the increased synthesis of triglycerides and phospholipids in zinc deficiency may be due to the increased availability of substrates as well as to increased activities of the enzymes involved in these processes.
Inhibition of hepatic cholesterol biosynthesis by chloroquine
Authors: Beynen Anton C. , Van Der Molen Ate J. , Geelen Math J. H. 
Published: November 2006

AbstractChloroquine is shown to be a potent inhibitor of cholesterol biosynthesis by isolated rat hepatocytes. Half‐maximal inhibition of cholesterogenesis occurs at ca. 10μM chloroquine. Chloroquine does not affect fatty acid synthesis by isolated hepatocytes. This suggests that chloroquine acts on the cholesterol biosynthetic pathway beyond the cytosolic acetyl‐CoA branchpoint of cholesterol and fatty acid synthesis.
Obesity: Can some fat cells enlarge while others are shrinking?
Authors: Aswell Margaret , Meade C. J. 
Published: November 2006

AbstractCBA mice were made obese by injection with gold thioglucose (GTG). After receiving transplants of “lean” and “GTG‐obese” fat under separate kidney capsules, the host mice were fed a restricted diet for three weeks. Over this period, the fat cells in the lean grafts enlarged whereas the fat cells in the GTG‐obese grafts shrank. Concurrent fat loss and fat gain can therefore take place.
Metabolism of epoxidized phosphatidylcholine by phospholipase A2 and epoxide hydrolase
Authors: Sevanian Alex , Stein Robert A. , Mead James F. 
Published: November 2006

AbstractThe isolation and measurement of phospholipid epoxides as major peroxidation products in biomembrane preparations prompted an investigation of enzymatic mechanisms which may be responsible for their elimination. Analysis of microsomal epoxide hydrolase and phospholipase A2 activity against a phospholipid epoxide commonly encountered in tissues indicated it to be a poor substrate for epoxide hydrolase, but rapidly hydrolyzed by phospholipase A2. Microsomal and purified phospholipase A2 preparations hydrolyzed the phospholipid epoxide at rates 2‐fold greater than were observed with a monoenoic phospholipid from which the epoxide would be derived. The product fatty acid epoxide,cis‐9,10‐epoxystearic acid, was rapidly hydrated by microsomal and cytosolic epoxide hydrolase. On the basis of earlier reports demonstrating increased phospholipase activity against oxidized phospholipids, and on the results of the present study, a model for the metabolism of oxidized membrane phospholipids is proposed.
Phase behavior of triolein and tripalmitin detected by differential scanning calorimetry
Authors: Hale John E. , Schroeder Friedhelm 
Published: November 2006

AbstractThe thermotropic behavior of triolein, tripalmitin and their mixtues was determined by differential scanning calorimetry. Polymorphic behavior was noted for the triglycerides but the triglycerides were converted to a single form after 4 to 5 successive heating scans. Melting points for each triglyceride were determined for the pure samples and mixtures, and plotted as a phase diagram. The phase diagrams indicate that a phase separation of triglycerides occurred at all concentrations of triolein and tripalmitin. However, the melting peak onset temperature of tripalmitin was shifted by triolein from 56 C at 100 mol % tripalmitin to 37 C at 15 mol % tripalmitin. Similarly, the peak onset temperature of triolein was shifted by tripalmitin from −2.5 C at 100% triolein to −4 C at 95% triolein. Enthalpies were also determined for pure samples and mixtures. These data indicated that when either triolein or tripalmitin were present as the minor component of the mixture, the enthalpy of the minor component was reduced whereas that of the major component was not greatly altered.
Inhibition of LCAT in plasma from man and experimental animals by chlorpromazine
Authors: Bell Frank P. , Hubert Edna V. 
Published: November 2006

AbstractChlorpromazine (CPZ), a major tranquilizer, was found to be a potent inhibitor of lecithin:cholesterol acyltransferase (LCAT, EC 2.3.1.43) in the plasma of normal man, rat, rabbit and dog in vitro. The inhibitory effect of CPZ reached 35–50% at 0.5 mM depending on species; dog plasma LCAT appeared to be somewhat more sensitive than that of the other species. In rats fed CPZ or lidocaine for 14 days (0.05% in the diet), there was no statistically significant change in total plasma cholesterol levels or the size of the plasma‐free (unesterified) cholesterol pool. However, 5 hr after an intracardial injection of [14C] cholesterol, the percentage of plasma [14C] cholesterol that was esterified was significantly lower (ca. 6%, p<0.05) in the CPZ‐treated group, suggesting that CPZ may also inhibit LCAT to some extent in vivo. The percentage of plasma [14C] cholesterol esterified in the lidocainetreated group was similar to control values and did not reflect its ability to inhibit LCAT in vitro.
Influence of lipid peroxidation on lipoprotein secretion by isolated hepatocytes
Authors: Dianzani M. U. , Poli G. , Gravela E. , Chiarpotto E. , Albano E. 
Published: November 2006

AbstractIsolated rat liver cells have been exposed to 3 different lipid peroxidation‐inducing agents, CCl4, FeCl3 and cumene hydroperoxide, and the rates of malonaldehyde production and of lipoprotein secretion have been compared. Results indicate that it is possible to induce a high degree of lipid peroxidation without inducing strong changes in lipoprotein secretion. Only in CCl4‐poisoned hepatocytes is lipoprotein secretion strongly impaired. In this experimental condition, the effect of free radical scavengers, or inhibitors of lipid peroxidation, has been studied; the degree of covalent binding of CCl4 metabolites to hepatocyte proteins, as well as the behavior of both lipid peroxidation and lipoprotein secretion, have been evaluated. Promethazine and propyl gallate prevented malonaldehyde production, but neither agent reduced covalent binding nor improved secretion. Menadione, on the contrary, besides inhibiting malonaldehyde production, decreased covalent binding and protected against the impairment of secretion. These data lead to the conclusion that covalent binding of CCl4 metabolites, rather than lipid peroxidation products, accounts for the derangement of lipoprotein secretion in CCl4‐poisoned liver cells.
Age‐related changes in biological parameters in Zucker rats
Authors: Bach André , Schirardin Henri , Bauer Marthe , Schaeffer Adrien , Weryha André 
Published: November 2006

AbstractChanges in a number of morphological and biochemical parameters were observed in genetically obese Zucker rats and in lean controls between 3 and 58 weeks of age. By 3 weeks, the genetically obese rats had higher proportional (wt/100 g body wt) and absolute amounts of adipose tissue, hyperlipemia affecting all the lipid fractions, and hyperproteinemia compared to lean controls. Obesity, hepatomegaly, high concentrations of hepatic lipids and hyperinsulinemia did not appear until the fifth week. In obese animals, liver lipid concentration reached a maximum at 17 weeks of age and then declined. During this time, the triacylglycerol concentrations in the serum remained stable, whereas the cholesterol and phospholipid concentrations continued to increase. The glycogen concentration in obese animals increased, both absolutely and compared to lean controls, between the 12th and 43rd week of age. From weaning, the Zucker rats, compared to lean controls, exhibited characteristics of obesity (accumulation of adipose tissue, hyperlipemia and hyperproteinemia), which persisted to the age of 58 weeks.
Essential fatty acid supplemented diet increases renal excretion of prostaglandin E2 and water in essential fatty acid deficient rats
Authors: Hansen Harald S. 
Published: November 2006

AbstractWeanling male rats were fed an essential fatty acid (EFA)‐deficient diet for 25 weeks and then switched to an EFA‐supplemented diet for 3 weeks. Control rats received the EFA‐supplemented diet for 25 weeks and then the EFA‐deficient diet for 3 weeks. Throughout the last 19 weeks, the rats were housed in metabolic cages once a week for a 24‐hr period. Urinary excretion of prostaglandin E2 (PGE2) was estimated by radioimmunoassay. Throughout a period of 12 weeks (weeks 13–24) water consumption increased ca. 60%, and urine output and PGE2 excretion decreased ca. 45% and 70%, respectively, in the EFA‐deficient rats. Feeding EFA‐supplemented diet to the EFA‐deficient rats for 3 weeks decreased the water consumption and raised the urine output to that observed in the controls. However, the urine output was corrected within 1 day whereas the water consumption was not corrected until the second measurement 8 days after the dietary change. The PGE2 excretion increased more than 9‐fold (from 18±8 ng/24 hr to 165±51 ng/24 hr) 1 day after EFA‐supplementation, followed by a decrease to 86±29 ng/24 hr over the following 2 weeks. On the basis of the present data, it is suggested that EFA deficiency in rats causes diminished PGE2 excretion, which can be normalized by EFA supplementation. The normalization of the urine flow may, in part, be caused by the concomitant considerable increase in endogenous PGE2 synthesis.
Separation of molecular species of ceramides as benzoyl andp‐nitrobenzoyl derivatives by high performance liquid chromatography
Authors: Do Un Hoi , Pei P. T. , Minard Robert D. 
Published: November 2006

AbstractCeramides were subjected to direct separation and structural analysis by high performance liquid chromatography after derivatization with benzoyl andp‐nitrobenzoyl chloride. The structures of benzoyl andp‐nitrobenzoyl derivatives of a representative ceramide, N‐heptadecanoyl D‐sphingosine, were fully characterized by mass spectrometry. Excellent separation of molecular species of ceramides was achieved with a 10‐μ LiChrosorb RP18 column by isocratic elution. Both the acyl group and the long‐chain base moiety were separated on this reverse‐phase column. The method has been used to determine quantitatively molecular species of nonhydroxy ceramides derived from bovine brain and egg yolk. Comparison of gas liquid chromatographic and high performance liquid chromatographic assays of intact ceramides was made.
Major hydrocarbons of the post‐pharyngeal glands of mated queens of the red imported fire antSolenopsis invicta
Authors: Thompson Malcolm J. , Glancey B. M. , Robbins William E. , Lofgren Clifford S. , Dutky Samson R. , Kochansky Jan , Vandermeer Robert K. , Glover Adrienne R. 
Published: November 2006

AbstractThin layer and column chromatographic analyses showed that hydrocarbons were the major lipoidal components of post‐pharyngeal glands of mated queens of the red imported fire ant,Solenopsis invicta. Gas liquid chromatographic analyses on an OV‐17 column showed four major hydrocarbons which have been identified and confirmed by synthesis and comparative mass spectral analyses as 13‐methylheptacosane, 13,15‐dimethylheptacosane, 3‐methylheptacosane, and 3,9‐dimethylheptacosane. When microgram quantitites of the natural alkanes on filter paper were placed in colonies of ants, the ants clustered on the paper about the sample and proceeded to masticate the paper in the area containing the alkanes.