bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of the thin layer chromatography/flame ionization detection system with other methods for the quantitative analysis of liver lipid contents in alcohol‐fed rats and controls
Authors: Rao G. Ananda , Riley Diana E. , Larkin Edward C.
Published: November 2006

In this study, we have examined the feasibility of using the Thin Layer Chromatography/Flame Ionization Detection (TLC/FID) system to evaluate the lipid content of alcohol‐induced fatty liver by comparing the results with those from other methods. Various amounts of standards (tripalmitin, phosphatidylcholine and cholesterol) were spotted on Chromarods and scanned either with or without development in a solvent system. The detector responses were significantly greater when the spots were not developed. From the results with developed rods, conversion factors (amount/area) were calculated. These were used for the quantitative analysis of the liver lipids from rats fed a Lieber‐DeCarli ethanol diet or a control diet for four weeks. The triglyceride (TG), phospholipid (PL), cholesterol (CH) and cholesterol ester (CE) contents (65.9, 25.4, 2.9 and 6.8 mg/g, respectively) obtained by the TLC/FID system were similar to those observed by other methods (67.9, 27.6, 3.0 and 8.3 mg/g, respectively). The liver lipid content in control rats also was similar to that obtained by other methods (TG, 19.0 vs 20.6; PL, 24.2 vs 21.8, CH, 2.1 vs 2.1 and CE, 1.8 vs 2.6 mg/g). Thus, the magnitude of changes in liver lipid levels due to chronic alcohol ingestion obtained by alternate methods also was found with TLC/FID. The TLC/FID system provides a convenient method for rapid analysis of the extent of fatty liver in alcohol‐fed animals.
Quantitating heart lipids: Comparison of results obtained using the Iatroscan method with those from phosphorus and gas chromatographic techniques
Authors: Kramer J. K. G. , Farnworth E. R. , Thompson B. K.
Published: November 2006

The precision and accuracy of the Iatroscan method was evaluated by comparing the results obtained with established phosphorus and gas chromatographic techniques. A complete lipid class analysis of rat heart lipids was chosen in order to evaluate the performance of the Iatroscan method for biological samples which contained both neutral lipids and phospholipids. A partial scan and repeat development with chloroform/methanol/water (68.5∶29∶2.5) was introduced to achieve consistently good separations of the phospholipids on the Chromarods in the Iatroscan method. The results showed that the precision of the Iatroscan method for some lipid classes was comparable to that of phosphorus or gas chromatographic techniques, while for other lipid classes it was lower. Compared to the data obtained using the phosphorus method, the Iatroscan data were generally similar, while the gas chromatographic method generally gave lower values. These findings, together with the advantages of time required for analysis, size of sample, and universality of detection, suggest that the Iatroscan is a valuable complementary method for complex lipid analyses.
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

Two 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

The 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

The 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

Rats 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

The 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

The 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

Fatty 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

The 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

A 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

The 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

Chloroquine 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

CBA 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

The 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

The 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

Chlorpromazine (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

Isolated 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

Changes 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

Weanling 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

Ceramides 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

Thin 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.
Effect of diabetes and insulin replacement on the lipid properties of hepatic smooth endoplasmic reticulum
Authors: Holloway Caroline Tobia , Garfield Sanford A.
Published: November 2006

This study is a characterization of the lipid properties of the smooth and rough endoplasmic reticulum (SER, RER) of liver from streptozotocin‐induced diabetic rats. A significant decrease in membrane microviscosity was observed in the SER but not the RER of diabetic rats when compared to that of normal controls. This decrease in SER membrane microviscosity correlated with a decrease in cholesterol/phospholipid ratio of these membranes that could be accounted for solely by a change in the membrane cholesterol content. Changes in phospholipid fatty acyl chain composition were also observed in the SER membranes but these changes were small when compared to the large change in cholesterol content observed. Insulin treatment for only one day did not significantly alter the microviscosity of the SER but after 2, 4 and 6 days of treatment both membrane microviscosity and membrane cholesterol content were restored to values similar to those for normal animals. No significant changes in the RER lipid composition were observed. It is well known that increases in glucose‐6‐Pase (G‐6‐Pase) activity of liver ER membranes are associated with diabetic onset. An increase in the specific activity of G‐6‐Pase was observed in both SER and RER membrane preparations, although the observed increase in the SER membrane is higher. The changes in the G‐6‐Pase activity of the SER membranes were correlated with the alterations in the microviscosity and lipid composition of these membranes. It is postulated that lipid properties of the SER membranes, may contribute to the regulation of G‐6‐Pase activity in that membrane.
Occurrence of mixtures of geometrical isomers of conjugated octadecatrienoic acids in some seed oils: Analysis by open‐tubular gas liquid chromatography and high performance liquid chromatography
Authors: Takagi Toru , Itabashi Yutaka
Published: November 2006

Analytical methods to obtain the detailed compositions of the fatty acids in oils containing more than one conjugated octadecatrienoic acid by open‐tubular gas liquid chromatography (GLC) and by reversed‐phase high performance liquid chromatography (HPLC) were established. Effective GLC separations ofcis,trans,trans‐9,11,13‐octadecatrienoic acid (ctt‐9,11,13–18∶3),ctc‐9,11,13–18∶3,ttc‐9,11,13–18∶3,ttt‐9,11,13–18∶3,ttc‐8,10,12–18∶3, andttt‐8,10,12–18∶3 were obtained with an opentubular column coated with the nonpolar liquid phase OV‐1 using an instrument having all‐glass carrier gas pathways. The HPLC method also gave satisfactory separations for the isomeric conjugated octadecatrienoates on the basis of number of thecis andtrans double bonds. Two or three minor conjugated trienoic acids were found along with the principal conjugated trienoic acid in tung oil, and seed oils of cherry,Prunus sp., Momordica charantia, Trichosanthes anguina, Punica granatum, Catalpa ovata, andCalendula officinalis. The mechanism for the formation of the conjugated trienoic acid mixtures in the seed oils is discussed. TheC. ovata seed oil also containedct andtt‐9,12‐octadecadienoic acids. Thett isomer is presumed to be a precursor ofttc‐9,11,13–18∶3, the main conjugated trienoic acid in this oil.
Molecular packing and stability in the gel phase of curved phosphatidylcholine vesicles
Authors: Lichtenberg D. , Schmidt C. F.
Published: November 2006

The instability of small unilamellar phosphatidylcholine vesicles in the gel phase can be understood as the effect of gel phase structural parameters on the intrinsic packing asymmetry of the vesicles.
Sterols and their biosynthesis in some freshwater bivalves
Authors: Popov S. , Stoilov I. , Marekov N. , Kovachev G. , Andreev St.
Published: November 2006

A number of free sterols and sterol esters of three freshwater mussels was separated and identified. A slow rate of biosynthesisde novo of sterols was demonstrated inAnodonta cygnea. Injected cholesterol was found to undergo esterification, oxidation, Δ22‐dehydrogenation and C‐24 alkylation. Methyl‐[14C]methionine was proved to be incorporated in C‐24 alkylsterols. Abnormally large amounts of cholesterol injected inA. cygnea were metabolized toward restoration of the normal composition of sterols. This was achieved by intensified metabolism of cholesterol, mainly by conjugation, oxidation and Δ22‐dehydrogenation.
Phospholipids and component fatty acids of the pigeon liver
Authors: Desmeth M. , Vandeputte‐Poma J.
Published: November 2006

The phospholipids from the livers of adult pigeons were separated by thin layer chromatography and the component fatty acids analyzed by gas liquid chromatography. They consisted of 53.0% phosphatidylcholine, 26.3% phosphatidylethanolamine, 8.6% sphingomyelin, 6.3% cardiolipin and 4.8% lysophosphatidylcholine. Phosphatidylethanolamine and phosphatidylcholine were characterized by a high concentration of long‐chain polyunsaturated fatty acids with the highest percentages in the phosphatidylethanolamine. Sphingomyelin contained up to 64.5% saturated acids. About 80% of the fatty acids present in the cardiolipin fraction consisted of linoleic acid. The liver phospholipids had the same composition in lactating as in nonlactating pigeons, but differed in many respects from those available in the crop‐milk.
Effects of ethanol diets on cholesterol content and phospholipid acyl composition of rat hepatocytes
Authors: Smith Thomas L. , Vickers Alison E. , Brendel Klaus , Gerhart Mary J.
Published: November 2006

Chronic treatment of adult male rats with ethanol liquid diets resulted in alterations in phospholipid and cholesterol contents as well as the acyl composition of phosphatidylethanolamine (PE), phosphatidylinositol (PI)‐phosphatidylserine (PS) mixture, and phosphatidylcholine (PC) of isolated hepatocytes. The influence of ethanol on these lipids was largely dependent on the proportion of dietary fat. Phospholipid and total cholesterol contents were elevated 23 and 27%, respectively, by ethanol when offered in a low‐fat diet (5% corn oil). Only the percentage of arachidonic acid from PI‐PS was significantly reduced in the low‐fat ethanol group. Exposure to a high‐fat (34% corn oil) diet in the presence of ethanol for 4–5 weeks resulted in a significant decrease in arachidonate/linoleate ratios of hepatic PE, PS‐PI and PC, while total phospholipid content remained constant. In the high‐fat, ethanol‐treated group, hepatic cholesterol content was increased 2‐fold. These results suggest that the level of dietary fat plays an important role in determining the effects of chronic ethanol consumption on hepatic cholesterol content and phospholipid acyl composition.
Absorption and distribution of orally administered jojoba wax in mice
Authors: Yaron A. , Samoiloff V. , Benzioni A.
Published: November 2006

The liquid wax obtained from the seeds of the arid‐land shrub jojoba (Simmondsia chinensis) is finding increasing use in skin treatment preparations. The fate of this wax upon reaching the digestive tract was studied.14C‐Labeled wax was administered intragastrically to mice, and the distribution of the label in the body was determined as a function of time. Most of the wax was excreted, but a small amount was absorbed, as was indicated by the distribution of label in the internal organs and the epididymal fat. The label was incorporated into the body lipids and was found to diminish with time.Lipids 17: 169–171. 1982.
Role of steroids and triterpenoids in the growth and reproduction ofPhytophthora cactorum
Authors: Nes W. David , Saunders Gary A. , Heftmann Erich
Published: November 2006

The life cycle ofPhytophthora cactorum, a fungal pathogen unable to epoxidize squalene, is controlled by certain combinations and concentrations of polycyclic isopentenoids normally found in the host plant. Data that lend support to this view are given. The fungus is capable of discriminating between various types and amounts of steroids and triterpenoids in terms of their uptake, metabolism, and effects on growth and reproduction. While certain sterols as well as triterpenoids stimulate growth, onlysterols induce significant oospore production. Steroidal alkaloids and estradiol are fungistatic and inhibit sterol‐induced oospore production. The primary difference in the metabolism of sterols and triterpenoids is that the sterols are converted to both esters and glycosides, whereas the triterpenoids are only esterified. The results demonstrate the importance of sterols and their products, compared to other polycyclic isopentenoids, as promoters of growth and reproduction and suggest that the preference for sterols may have its origin in the adaptation to host‐parasite interactions.
The quantitative analysis of plant sterols
Authors: Knights B. A.
Published: November 2006

Two methods for the quantitative analysis of plant sterols have been described. In the first, cholesterol is used for control of recovery and gas liquid chromatography (GLC) analysis. When cholesterol is present in the sterol mixture, a radioactive standard (usually cholesterol or sitosterol) is used to control recovery, and coprosterol is used to monitor GLC. The methods are exemplified for nitrogenfixing root nodules and for chloroplasts, respectively.
Response ofDrosophila tocis‐ andtrans‐22‐dehydrocholesterol: I. A survey
Authors: Kircher Henry W. , Phariss Rebecca L. , Rosenstein Fumiko U. , Baldwin David , Fogleman James C.
Published: November 2006

Cis‐ andtrans‐22‐dehydrocholesterol were added to media for 10 species ofDrosophila. Thecis isomer prevented normal maturation of 4 species and thetrans isomer was toxic to 9. These findings were corroborated by tests with 4 representative species on a sterol‐deficient medium under axenic conditions. Addition of cholesterol to the latter overcame the toxicity of thetrans isomer.Trans‐22‐dehydrocholesterol may be acting as a competitive inhibitor in the metabolism of phytosterols to cholesterol or ecdysone by the insects.
Taxonomic implication of sterol composition in the genusChlorella
Authors: Holden Marcia J. , Patterson Glenn W.
Published: November 2006

Thirty‐five isolates of the genusChlorella were grown under standardized conditions and analyzed for sterol composition. Six different sterol synthetic patterns were found. Two patterns were characterized by nuclear unsaturation at C‐5 and one type by nuclear unsaturation at C‐7. The remaining isolates all synthesize sterols with a diunsaturated nucleus (C‐5+C‐7) with various modifications. Subtype 1 synthesizes only C28 sterols, subtype 2 produces C28 and C29 sterols, and subtype 3 (1 isolate) produces C28 sterols with nuclear unsaturation at C‐5+C‐8 in addition to the Δ5,7 C28 sterols seen in the first 2 subtypes. Comparison of the sterol composition of strains shared in common with taxonomic researchers showed good correlation with the taxonomic scheme of Fott and Novakova which has been confirmed by Kessler and coworkers using other biochemical markers.
The role of squalene synthetase in the inhibition of tetrahymanol biosynthesis by cholesterol inTetrahymena pyriformis
Authors: Warburg Colin F. , Wakeel Marwa , Wilton David C.
Published: November 2006

The biosynthesis of the triterpenoid alcohol tetrahymanol byTetrahymena pyriformis is rapidly inhibited by the addition of cholesterol to the growth medium. The primary site of this inhibition by cholesterol has been established to be at the level of the enzyme squalene synthetase. The protein synthesis inhibitor cycloheximide produces an identical decline in squalene synthetase activity to that of cholesterol and the half‐life of the enzyme is about 50 minutes. No direct inhibition of the enzyme is observed and suggests that cholesterol inhibits the actual synthesis of the enzyme squalene synthetase. Farnesol is accumulated during in vitro incubations derived from cells grown in the presence of cholesterol or cycloheximide.
Microsomal enzymes of cholesterol biosynthesis from lanosterol: A progress report
Authors: Trazaskos James M. , Bowen Wayne D. , Fisher Gary J. , Billheimer Jeffrey T. , Gaylor James L.
Published: November 2006

Our principal goal is the complete resolution and reconstitution of the microsomal enzymes of cholesterol biosynthesis. Elucidation of the enzymology has been achieved primarily through dissection of the membrane‐bound, 19‐step multienzymic process. This report describes the dissection approach through both interruption of specific steps and reconstitution of enzymes that catalyze oxidation of the 14α‐methyl group. In earlier work, 4‐demethylation was resolved into 3 component reactions catalyzed by: 4‐methyl sterol oxidase (NAD[P] H‐ and O2‐dependnet); steroid 4α‐carboxylic acid decarboxylase (NAD‐dependent); and 3‐ketosteroid reductase (NADPH‐dependent). The 3‐ketosteroid reductase and decarboxylase have been solubilized with Lubrol WX and deoxycholate, respectively, and characterized. The 4‐methyl sterol oxidase (cytochrome b5‐dependent) recently has been solubilized with Renex 690. This study represents successful elucidation of a microsomal enzyme sequence by interruption of the central 10‐step segment of the multienzymic formation of cholesterol from lanosterol. The initial C‐32 oxidative reaction of 14α‐methyl group elimination is catalyzed by a from of cytochrome P‐450 that is induced by isosafrole. The induced cytochrome P‐450 has been solubilized with Emulgen 913 and purified to homogeneity (17 nmol of cytochrome/mg protein). 24,25‐Dihydrolanosterol is oxidized by combination of cytochrome P‐450 reductase, hematin, NADPH, glutathione, and the purified, isosafrole‐induced cytochrome in an artificial liposome. Oxidation product identification is underway. This study represents successful elucidation of a microsomal multienzymic sequence by solubilization and reconstitution of a segment of the pathway. The remaining enzymes under study are the Δ8→Δ7 isomerase and 3 NADPH‐dependent double bond reductases that catalyze reduction of: Δ7, Δ14‐ Δ24‐sterol double bonds. Purification of these nonoxygenrequiring enzymes is in progress. Resolution of the enzymes has demonstrated unequivocally that cholesterol synthesis via this pathway could not have appeared biologically until membranes containedboth the cytochrome P‐450‐ and cytochrome b5‐electron transport enzymes. Chemically, all enzymic attacks in the formation of cholesterol from lanosterol appear to be initiated on the α‐face of the relatively planar steroids. Thus, considerable genetic pressure must have been needed for the stereospecific clearing of the steroidal α‐face to form the mature membrane component, cholesterol.
Kinetic analysis of plasma VLDL‐TG and VLDL‐remnant‐TG turnover in anesthetized rats
Authors: Bickerstaffe Roy , Lyon Irving , Rostami Hojat , Baker Nome , Elovson John
Published: November 2006

We have estimated the turnover and relative pool sizes of nascent‐VLDL‐TG and VLDL‐remnants‐TG in anesthetized rats. [1‐14C]Palmitoyl‐ and [2‐3H]glyceryl‐labeled “VLDL”‐TG (including nascent VLDL‐TG and VLDL‐remnants‐TG) were prepared by injecting labeled palmitate and glycerol into donor rats. Labeled serum from these rats was then injected intravenously into nembutalized male rats and serial blood samples taken for 30 min. Special care was taken to define any early components in the labeled “VLDL”‐TG disappearance curves. In other experiments, the donors were rendered functionally hepatectomized 30 min after injection of3H‐glycerol and the endogenous labeled VLDL‐TG was allowed to circulate 30–60 min before collection of the TG‐labeled VLDL‐remnants‐containing serum. The latter was injected into 4 recipient nembutalized rats and the remnant‐TG‐turnover measured by serial sampling as above. In two cases,14C‐“VLDL” and3H‐VLDL‐remnants were injected as a single bolus into ether‐anesthetized rats. Despite its complex composition, “VLDL”‐TG in most cases disappeared in a single exponential fashion for 30 min with an average half‐life of 5.9 min in nembutalized and 2.8 in ether‐anesthetized rats. VLDL‐remnants‐TG showed a more complex behavior, but contained a major rapid component with a mean t1/2 of ca. 1.5 min in both groups. The data, analyzed by multicompartmental analysis, were fitted to a simple model in which turnover of a larger nascent VLDL‐TG pool with formation of a more rapidly turning over smaller pool of VLDL‐remnant‐TG is the rate‐limiting step in overall TG removal from the d<1.006 fraction of rat serum. The data are consistent with our theoretical prediction that under these conditions the kinetics of the VLDL‐remnants cannot be resolved from analysis of the total composite “VLDL” (nascent plus remnant) pool.
Lipid and fatty acid composition of the endogenous energy sources of striped bass (Morone saxatilis) eggs
Authors: Eldridge Maxwell B. , Joseph Jeanne D. , Taberski Karen M. , Seaborn Gloria T.
Published: November 2006

The unique physiological flexibility of the early life stages of striped bass is attributed to the calorierich endogenous energy sources of the striped bass egg. Eggs of different aged striped bass from geographically separate populations were examined for lipid and fatty acid compositions and were found to be basically similar. Yolk components of the eggs contained significantly less total lipid than oil globules, were more diverse in lipid class composition and consisted mostly of polar lipids. Oil globules were entirely lipid material consisting predominantly of steryl/wax esters. Fatty acid compositions of yolk and oil globules differed according to their respective lipid compositions. The functional significance of these lipids is discussed in relation to the ecological context of the early life stages.
Bovine pulmonary surfactant: Chemical composition and physical properties
Authors: Yu Sue , Harding Paul G. R. , Smith Norman , Possmayer Fred
Published: November 2006

Bovine pulmonary surfactant was obtained by endotracheal lavage of lungs from newly slaughtered cows followed by differential centrifugation. Lipid extracts of bovine surfactant contained 3% neutral lipid, mainly as cholesterol and diacylglycerol and 97% phospholipid. Phosphatidylcholine (79%) and phosphatidylglycerol (11%) accounted for most of the phospholipids with smaller amounts of phosphatidyl‐ethanolamine, phosphatidylinositol, lyso‐bis‐phosphatidic, acid and sphingomyelin. Fatty acid analysis revealed high levels of palmitate in phosphatidylcholine and to a lesser extent phosphatidylglycerol, but not in the other diacylphospholipids. Phosphatidylcholine was 53% disaturated and phosphatidylglycerol was 23% disaturated. Monoenoic species accounted for the major proportion of the remaining, lipid. The protein content was 10% as estimated by the Lowry procedure and 5% when determined by amino acid analysis. Extraction with chloroform/methanol removed ca. 90% of the protein but had no effect on the surfactant properties as evaluated by a pulsating bubble technique.
Sterol synthesis from biliary squalene in the jejunal mucosa of the rat in vivo
Authors: Strandberg T. E.
Published: November 2006

Because bile contains substantial amounts of cholesterol precursors, e.g., squalene and differnet methyl sterols, the fate of biliary squalene was studied by incubating isolated jejunal loops of the rat in vivo with bile containing3H‐squalene and14C‐cholesterol. After 90 min, no radioactivity was found in plasma lipids. Closer analysis of gut epithelium revealed that both labeled compounds were preferentially taken up by the villous cells. Biliary3H‐squalene was absorbed almost completely and was further cyclized to free and esterified methyl sterols and cholesterol. Whereas squalene not cyclized to sterols stayed in the mucosa, the newly synthesized sterols were transferred to lumen. The lipid patterns of gut lumen and mucosal cells were quite different, suggesting that the transfer of the newly synthesized lipid to intestinal lumen was not due to the desquamation of epithelial cells alone. The results suggest that biliary cholesterol precursors can contribute to the cholesterol production of the jejunal villous cells bypassing the rate‐limiting step of the cholesterol synthesis pathway, and to the “nonexchanging” fecal neutral sterols of the rat.
Glycolipids and thylakoid proteins in chloroplasts and streptomycin‐bleached lamellae ofEuglena
Authors: Skowronski Gloria A. , Garrigan Owen W.
Published: November 2006

Thylakoid proteins from (a) the chloroplasts of greenEuglena gracilis cells and from (b) the corresponding concentric lamellar bodies of streptomycin‐bleachedEuglena have been extracted in aqueous sodium dodecyl sulfate (SDS) and purified. The molecular weights of the proteins, determined by polyacrylamide gel electrophoresis in SDS, were 9 kilodaltons for (a) and 9 and 11.5 kilodaltons for the 2 polypeptide chains of (b). Each of the purified proteins consists of 55% apolar and 45% polar amino acids. The lipids of the green and bleached cells differ in polarity of components. Neutral galactolipids are abundant in green cells but not in streptomycin‐bleached cells. Anionic sulfolipid content is greater in the chlorotic organisms. Polyenoic fatty acids, mainly with 16, 18 and 19 carbon atoms, occur in the green cell galactolipids. Cells grown in the presence of streptomycin are, in contrast, rich in monoenes. The opposite is observed in the sulfolipids: monoenes with 16 and 20 carbons are the main fatty acids in the green cells, while a dienoic fatty acid with 12 carbons is found in large amounts in streptomycin‐bleached cultures.