bluuebunny/crossref_metadata_2025 huggingface dataset:
The role of gastric lipolysis on fat absorption and bile acid metabolism in the rat
Authors: Roy C. C. , Roulet M. , Lefebvre D. , Chartrand L. , Lepage G. , Fournier L. A.
Published: November 2006

In vivo studies were carried out in young Sprague‐Dawley rats to examine the role of gastric lipolysis on fat absorption and bile acid metabolism. When fed by gastric perfusion 5 times (corn oil, 4 g/day) their usual dietary intake of fat, rats deprived of lingual lipase by the creation of an esophageal fistula had a significant degree of fat and bile acid malabsorption as well as a shortened bile acid halflife when compared to animals with a gastrostomy. The % fat absorption, bile acid loss and bile acid pool were normal in 2 groups of esophageal fistula rats fed the same quantity of corn oil or twice (8 g/day) that amount as a fine emulsion. In view of a negligible gastric lipase activity in animals with an esophageal fistula and of decreased hydrolysis of a triglyceride test meal, these data suggest that gastric lipolysis is of physiological importance in situations where lipolytic mechanisms are stressed by a large fat intake. Its principal role is to potentiate intestinal lipolysis by facilitating the emulsification of dietary lipids through its formed products and, therefore, the contact of pancreatic lipase with its substrates.
Synthesis of saturated, unsaturated, spin‐labeled, and fluorescent cholesteryl esters: Acylation of cholesterol using fatty acid anhydride and 4‐pyrrolidinopyridine
Authors: Patel K. M. , Sklar L. A. , Currie R. , Pownall H. J. , Morrisett J. D. , Sparrow J. T.
Published: November 2006

A rapid, high yield method for the preparation of cholesteryl esters is described. The method is a modification of the catalytic procedure previously applied to the acylation of sn‐glycero‐3‐phosphoryl‐choline (Patel, K.M., J.D. Morrisett, and J.T. Sparrow, J. Lipid Res., 20:676 (1979). Cholesteryl esters are formed in excellent yield by acylating cholesterol with fatty acid anhydride or fatty acid and dicyclohexylcarbodiimide in methylene chloride containing 4‐pyrrolidinopyridine. The versatility of the method is demonstrated by the preparation of the cholesteryl esters of saturated, unsaturated, spinlabeled, and labile fluorescent fatty acids.
Incorporation of label from [9, 10‐methylene‐14C] sterculic acid in rainbow trout,Salmo gairdneri
Authors: Eisele T. A. , Parker R. S. , Yoss J. K. , Nixon J. E. , Pawlowski N. E. , Sinnhuber R. O.
Published: November 2006

The distribution of radioactivity from sterculic acid, labeled on the 9,10‐methylene carbon of the cyclopropene ring, was investigated in trout,Salmo gairdneri. Fifty percent of the administered dose was excreted in feces and urine by 168 hr, but less than 1% of the dose was expired as carbon dioxide during the same time period. Incorporation of radioactivity into most organs peaked at 119 hr, and the majority of the label in the liver was in the fatty acid portion of the lipid fraction. Total lipid radioactivity in liver was higher in trout conditioned to cyclopropene lipids, and a substantial amount of label was found in phosphatidylcholine and ethanolamine phospholipids as well as neutral lipid. The data demonstrate that rainbow trout readily absorb, transport and incorporate sterculic acid into tissue lipid, including membrane lipid, but cannot oxidize the methylene carbon of the cyclopropene ring to carbon dioxide.
Reproduction and survival of rainbow trout (Salmo gairdneri) fed linolenic acid as the only source of essential fatty acids
Authors: Yu T. C. , Sinnhuber R. O. , Hendricks J. D.
Published: November 2006

A semipurified test diet containing 1% linolenate as the sole dietary essential fatty acid was fed to a group of rainbow trout (Salmo gairdneri) for 34 months. The fish matured and the eggs produced were hatched. The second generation fry were fed our laboratory diet for 3 months. The growth of these fry was normal. Histologic examinations revealed no abnormality in liver, heart and kidney tissues of the fry during the three month period.
Argentation chromatography on silver sulfamate‐impregnated silica gel layers
Authors: Ilinov Peter P.
Published: November 2006

Silver sulfamate was used in place of silver nitrate as argentation and charring reagent in thin layer chromatography (TLC). This reagent permits thin layer chromatographic separations of fatty acid esters with differing degrees of unsaturation as well as ofcis/trans isomeric fatty acids, and allows for direct charring of fractions. Examples given for separations on silica gel plates impregnated with silver sulfamate include cholesterol esters and fatty acid methyl esters.
Desaturation of positional and geometric isomers of monoenoic fatty acids by microsomal preparations from rat liver
Authors: Pollard Michael R. , Gunstone Frank D. , James Anthony T. , Morris Lindsay J.
Published: November 2006

A range ofcis‐ andtrans‐monoenoic fatty acids was tested as substrates for desaturation in microsomal preparations from rat liver.Trans‐monoenoic acids were generally desaturated in the Δ9 position to the same extent as stearic acid. Acids with Δ7‐trans‐ and Δ11‐trans‐olefinic unsaturation produced Δ7‐trans,9‐cis‐ and Δ9‐cis,11‐trans‐conjugated dienoic acids, respectively, but the Δ8‐trans‐ and Δ10‐trans‐monoenoic acids did not give Δ8,9‐ or Δ9,10‐allenes. Of thecis‐monoenoic acids examined, only those with double bonds at or beyond the Δ14 position gave any measurable Δ9 desaturation. When Δ9 desaturation of long chain saturated acids was inhibited by adding sterculic acid, these saturated acids were desaturated at the Δ5 and Δ6 positions. Many of the monoenoic acids tested were also desaturated at the Δ5 and/or Δ6 positions, although the percentage conversions were always low. Δ9‐cis,11‐trans‐, Δ9‐cis,12‐trans‐ and Δ9‐cis,13‐trans‐dienoic acids, produced in situ by Δ9 desaturation of the corresponding monoenoic acids, were extensively desaturated in the Δ6 position. These results are discussed in terms of: (a) the various models proposed to explain the substrate specificities of the desaturases, and (b) the metabolism of unnatural fatty acids ingested from dietary sources.
The fatty acid composition of three unicellular algal species used as food sources for larvae of the American oyster (Crassostrea virginica)
Authors: Chu Fu‐Lin E. , Dupuy John L.
Published: November 2006

The total lipid and fatty acid content of 3 algal species,Pyramimonas virginica, Pseudoisochrysis paradoxa andChlorella sp., which have been successful as food sources for rearing larvae of the American oyster,Crassostrea virginica, was determined. Of the fatty acids of ω6 and ω3 families which have been shown to be essential fatty acids for normal growth in many animals, only the ω6 fatty acids were found to be higher in these 3 species of algae than in the traditional oyster larvae diet which consists of the algaeMonochrysis lutheri andIsochrysis galbana. The major fatty acid constituents of the total lipids of the 3 species were the C12, C14, C16 and C18 saturated fatty acids and the C16 and C18 mono‐ and polyunsaturated acids. These components constituted 70–93% of the total lipid in cultures of all ages. There were modest amounts of C20 and C22 polyunsaturated acids; some of these existed only in trace amounts. InP. virginica andChlorella sp., hexadecanoic acid was dominant (23–39%). The presence of large quantities of tetradecanoic acid (22–26%) and oleic acid (17–21%) was characteristic ofP. paradoxa. Chlorella sp. had the highest proportion of octadecatrienoic acid (18∶3ω3) which accounted for up to 17% of the total lipids. γ‐Linolenic acid (18∶3ω6) was found only inChlorella sp., but in the 5th‐day culture only. The lowest proportion of total polyethylenic acid was inP. paradoxa; however, lipid analyses showed this alga had the most lipid/individual cell. Some variations were observed in the fatty acid composition with age of the culture.
Separation and purification of lecithins by high pressure liquid chromatography
Authors: Porter N. A. , Wolf R. A. , Nixon J. R.
Published: November 2006

Ten different synthetic lecithins have been analyzed by reverse‐phase high pressure liquid chromatography. An empirical lecithin “carbon number” that depends on the total number of carbons and double bonds in the fatty acyl chains in a useful index in predicting retention volumes of lecithins on a nonpolar octadecyl fatty acid column. Commercial egg lecithin is separated into its components by this technique.
1,25‐dihydroxyvitamin D3 increases the activity of the intestinal phosphatidylcholine deacylation‐reacylation cycle
Authors: O'Doherty P. J. A.
Published: November 2006

The activity of the intestinal phosphatidylcholine deacylation‐reacylation cycle has been found to be stimulated by 1,25‐dihydroxy‐vitamin D3. The stimulation of this cycle thus provides a possible mechanism for the reported retailoring of the fatty acid composition of phosphatidylcholine in intestinal cell membranes by 1,25‐dihydroxy‐vitamin D3 and its analogue, 1α‐hydroxyvitamin D3.
Determination of the absolute configuration at C‐20 and C‐24 of ergosterol in ascomycetes and basidiomycetes by proton magnetic resonance spectroscopy
Authors: Adler John H. , Young Michael , Nes William R.
Published: November 2006

Samples of ergosterol isolated fromSaccharomyces cerevisiae, Neurospora crassa, andAgaricus sp., and commercial ergosterol all displayed identical proton magnetic resonance (PMR) spectra at 220 MHz. From the effects produced on the doublet for C‐21 by epimerization at C‐20 and C‐24 in sterols of known configuration, the absolute configurations at these positions in ergosterol were determined. The data demonstrate that ergosterol from both Ascomycetes and Basidiomycetes is the same and that at C‐20 and C‐24, the two H‐atoms are on the α‐side of the asymmetric carbon atoms and that C‐22 istrans‐oriented with respect to C‐13 about the 17(20)‐bond.
Influence of fasting‐refeeding and dietary linoleate on liver glucose‐6‐phosphate dehydrogenase and phospholipid fatty acid composition in rats adapted to a purified diet
Authors: Williams M. A. , Tinoco J. , Ojakian M. A. , Clark L.
Published: November 2006

Responses to refeeding after fasting were studied in male rats fed a purified casein‐sucrose diet containing 5% safflower oil. After a 48 hr fast, the rats were fed either the same diet or the same diet minus oil (fat‐free diet). These experiments were designed to distinguish changes due to fasting and refeeding alone without a change of diet from those changes caused by refeeding a diet of different composition. In the first experiment, rats were refed for 3 or 7 days. In rats refed either diet, liver glucose‐6‐phosphate dehydrogenase (G6PD) activity was elevated above refasting levels, but after 7 days, activity in rats refed the 5% safflower oil diet was significantly lower than in those refed the fatfree diet. The amount of liver arachidonate in rats refed the safflower oil diet was the same during refeeding as before fasting. In the second experiment, rats were refed the fat‐free diet for 1, 2, 3, or 7 days. Liver G6PD and fatty acid synthetase were measured, as well as fatty acids in liver total lipids and phospholipids. G6PD activity increased above prefasting levels after one day refeeding and continued to increase, for 7 days. Fatty acid synthetase activity increased for the first 3 days of refeeding, with no additional increase after 7 days. In all rats refed the fat‐free diet, the proportions of arachidonate and linoleate in liver phospholipids diminished with time, and eicosatrienoate appeared. These results show that (a) maintenance of liver phospholipid arachidonate did not prevent increased G6PD activity in early refeeding, but the elevated G6PD activity later declined when phospholipid arachidonate was maintained by feeding a source of linoleate; (b) the metabolic state of fastedrefed rats had not returned to prefasting conditions even after 7 days of refeeding a linoleate‐rich diet to which the rats were adapted before fasting.
Pancreatic and microbial lipases: A comparison of the interaction of pancreatic colipase with lipases of various origins
Authors: Canioni P. , Julien R. , Rathelot J. , Sarda L.
Published: November 2006

Conjugated bile salts inhibit the hydrolysis of triglycerides (TG) by the lipases fromRhizopus arrhizus andGeotrichum candidum. This occurs for detergent concentrations similar to those which suppress the action of mammalian pancreatic lipases upon the same substrates. However, in opposition with what is observed with the latter enzymes, the activity is not restored by the addition of pancreatic colipase. Both pancreatic andR. arrhizus lipases are inactivated at tributyrin/water interface, but only the first enzyme is protected against this surface denaturation by the pancreatic cofactor. These observations suggest that colipases synthesized in mammalian pancreas display specific interaction towards the lipases made by the same organ.
Effects of dietary vitamin E, selenium, and polyunsaturated fats on in vivo lipid peroxidation in the rat as measured by pentane production
Authors: Dillard Cora J. , Litov Richard E. , Tappel Al L.
Published: November 2006

Starting at 21 days of age, groups of six rats each were fed a basal Torula yeast diet supplemented with 0,4% L‐methionine and varying amounts of vitamin E as dl‐alpha tocopherol acetate, selenium as sodium selenite, and with either 10% stripped corn oil, stripped lard, or coconut oil. By 7 wk, pentane production by rats fed a corn oil diet deficient in both vitamin E and selenium was twice that by rats fed 0.1 or 1 mg of selenium per kg of the same basal diet. Blood glutathione peroxidase activity after 7 wk was proportional to the logarithm of dietary selenium. Groups of rats fed the vitamin E‐ and selenium‐deficient diets with lard or coconut oil had one‐half the pentane production of rats fed the vitamin E‐ and selenium‐deficient corn oil diets. The plasma level of linoleic plus arachidonic acid was 1.8 times greater on a wt % basis in rats fed corn oil than in rats fed lard or coconut oil as the fat source. Pentane production by rats fed 40 i.u. dl‐alpha tocopherol acetate per kg of the selenium‐deficient corn oil diet was one‐sixth of that by rats fed the same diet without vitamin E; the plasma of the rats fed the vitamin E‐supplemented corn oil diet had a level of vitamin E that was about six times greater than that of the rats fed the vitamin E‐deficient corn oil diet.
Neural factors in experimental degenerative arteriopathy
Authors: Gutstein William H. , Parl Fritz
Published: November 2006

Intermittent electrical stimulation of the lateral hypothalamus of rats performed for 30 min to 6 hr, results in hyperlipidemia and endothelial cell damage of the aorta and coronary arteries. Hyperlipidemia is related to transient biliary obstruction elicited by hypothalamic stimulation and is characterized by elevation of the cholesterol, phospholipid, and triglyceride fractions. Endothelial cell damage is observed ultrastructurally as plasma membrane degeneration with detachment and the formation of large spaces (“vacuoles”). Thus, neural factors may be implicated in inducing conditions associated with early atherogenesis. Stimulation carried out for longer time intervals would be expected to produce more advanced lesions. However, the role of neural transmission per se (i.e., without hyperlipidemia) in producing arteriopathy is not clearly defined from these experiments. In rats, the lesser splanchnic nerve forms the major innervation of the abdominal aorta. In animals fed normal diets, chronic intermittent stimulation of this nerve (up to 3 weeks) resulted in advanced arteriosclerotic changes with intimal fibrosis and calcification. On histologic examination, lipid deposits appeared to be absent from these lesions. Animals stimulated for shorter periods of time exhibited earlier changes associated with atherogenesis, such as endothelial damage, elastic reduplication, and adherent microthrombi. Thus, direct neural transmission, especially if excessive, plays a role in producing arteriopathy. Hyperlipidemia, if persistent, could modify these lesions so that they would accumulate plasma lipids. Experiments to test this hypothesis are currently in progress.
Ecdysone metabolism: Ecdysone dehydrogenase‐isomerase
Authors: Nigg H. N. , Svoboda J. A. , Thompson M. J. , Kaplanis J. N. , Dutky S. R. , Robbins W. E.
Published: November 2006

An enzyme system that converts α‐ecdysone to its hormonally less active 3α‐epimer was detected only in the midgut of the tobacco hornworm,Manduca sexta (L.). This system appears to be specific for the ecdysones and may represent a metabolic control point for regulating molting hormone activity.
Effect of dietary bile acids, cholesterol, and β‐sitosterol upon formation of coprostanol and 7‐dehydroxylation of bile acids by rat
Authors: Cohen B. I. , Raicht R. F. , Mosbach E. H.
Published: November 2006

During studies of sterol metabolism in the rat, the fecal neutral sterol fraction was analyzed by a combination of thin layer chromatography and gas liquid chromatography. On a stock diet of rat chow supplemented with 5% corn oil, the rats excreted 14.5 mg/day of total neutral sterols. Coprostanol comprised 35% (5 mg/day) of this fraction. When the diet was supplemented with 0.5% sodium taurochenodeoxycholate, the amount of coprostanol in the feces remained the same as in the controls (3.2 mg/day, 32%). The addition of 0.5% sodium taurocholate to the diet resulted in a fivefold reduction of coprostanol formation (0.6 mg/day, 8%). When 1.2% cholesterol was added to the stock diet, the amount of coprostanol present in the feces decreased to an average of 11% compared to controls, but the absolute amount formed was greater (35 mg/day). On a diet enriched with 0.8% β‐sitosterol, the rats, on the average, converted 23% of the cholesterol to coprostanol. Feeding diets enriched with sodium taurochenodeoxycholate and sodium taurocholate reduced the 7‐dehydroxylation of primary bile acids in the feces by 28% and 42%, respectively. The conversion of primary bile acids to secondary bile acids in the feces of control, cholesterol, and β‐sitosterol fed rats was the same (64%).
Rapid transmethylation of microgram amounts of phosphatidylcholine on potassium methoxide/celite columns
Authors: Marmer William N.
Published: November 2006

A rapid and convenient method for the determination of acyl groups in phosphatidylcholine (PC) has been developed. Transmethylation reactions were carried out on potassium methoxideimpregnated Celite microcolumns that were readily prepared from Pasteur pipettes. The methods were tested on microgram amounts of synthetic L‐α‐phosphatidylcholines (di‐14∶0; di‐18∶2; α‐16∶0‐β‐14∶0) and on egg yolk lecithin, in methylene chloride or hexane solution. Transmethylation of these lipids occurred rapidly at room temperature. Gas liquid chromatographic (GLC) analysis of the product methyl esters demonstrated that the reaction was neither selective for one acyl position of PC over the other, nor sensitive to the amount of unsaturation within the acyl group. The results of the acyl group analysis of natural egg yolk lecithin compared favorably with the results from an established procedure.
Bile acids LVII. Bile acids and colorectal cancer
Authors: Davis J. Wendell , Elliott William H.
Published: November 2006

Significant correlations have been reported by epidemiologists between the mortality from colorectal cancer in various populations and the consumption of meat or lipids by these populations. These have directed considerable attention to possible relationships between diet and the occurrence of this neoplasm. We have carried out studies of the composition of bile from rats as influenced by diets of varying lipid content. Two cannulas were surgically implanted to form an externalized bile duct through which bile was drained from the common duct and returned to the duodenum. Small aliquots were analyzed for total bile acids by enzymatic assay and for individual bile acids by high‐pressure liquid chromatography, gas chromatography and gas chromatography‐mass spectrometry. Animals consuming diets highest in lipid content provided bile with the greatest amounts of bile acids. The primary bile acids, taurocholic, taurochenodeoxycholic, and tauro α‐ and β‐muricholic acids made up more than 99% of the 3α‐hydroxy bile acids and were found in approximate molar ratio of 2∶1∶1. Either complete drainage of bile without return to the duodenum, or biliary tract obstruction had pronounced influence on the rate of secretion of bile and its composition.
Leucine as an in vitro precursor to lipids in rat sciatic nerve
Authors: Stillway Lewis W. , Weigand Dorothy A. , Buse Maria G.
Published: November 2006

The in vitro incorporation of leucine, isoleucine and pyruvate into lipids was compared and the possibility that leucine might serve as anin situ precursor to the correspondingiso fatty acids in the rat sciatic nerve was studied. The relative incorporation of14C from leucine into lipids vs. nonlipids was 20%, and the incorporation of label into total lipids from leucine was one‐half that from pyruvate. The incorporation of label from leucine and pyruvate into sterols was nearly equivalent, but the incorporation of label into all other lipid classes from leucine was less than that from pyruvate, and the incorporation of label from isoleucine into lipids was much less in all cases. No detectable label from leucine was incorporated into brached chain fatty acids. It is concluded that leucine may be a substantial in vitro precursor to all major lipids in peripheral nerve, especially sterols. The possibility and significance of a leucine catabolic pathway in the cytosol in relation to availability of 3‐hydroxy‐3‐methylglutaryl CoA for sterol biosynthesis is discussed.
Interaction of human plasma high density lipoprotein HDL2 with synthetic saturated phosphatidylcholines
Authors: Gong Elaine L. , Nichols Alex V.
Published: November 2006

The interaction of human plasma high density lipoprotein HDL2 (d 1.063–1.125 g/ml) with sonicated dispersions of synthetic saturated phosphatidylcholines, dipalmitoyl‐ (diC16PC), dimyristoyl‐ (diC14PC), didodecanoyl‐ (diC12PC), didecanoyl‐ (diC10PC), and dioctanoyl‐ (diC8PC) L‐alpha phosphatidylcholine, was investigated. Incubation (4.5 hr, 37 C) of HDL2 with diC14PC, diC12PC, diC10PC and diC8PC followed by gradient gel electrophoresis or preparative ultracentrifugation resulted in a redistribution of apolipoprotein A‐I (apoA‐I). The extent of redistribution depended on the molar ratio of the phospholipid to HDL2 in the incubation mixture. Redistributed apoA‐I occurred as lipid‐free apoA‐I and/or as complexes of apoA‐I with phosphatidylcholine. Increasing the length of time of ultracentrifugation of the interaction mixtures did not increase the extent of redistribution. No redistribution of apoA‐I was detected following incubation and gradient gel electrophoresis or preparative ultracentrifugation of mixtures of HDL2 with dispersions of diC16PC.
Incorporation ofcis‐ andtrans‐octadecenoic acids into the membranes of rat liver mitochondria
Authors: Høy C. ‐E. , Hølmer G.
Published: November 2006

The incorporation of dietary isomeric fatty acids into the membranes of liver mitochondria was investigated. Three groups of rats were fed diets containing 3% sunflower seed oil plus 15%, 20%, or 25% partially hydrogenated arachis oil. A fourth group was fed 25% partially hydrogenated arachis oil, but no sunflower seed oil. All diets were given for 3, 6, or 10 weeks. After 10 weeks, the content oftrans fatty acids in the lipids of the mitochondrial membranes was 15–19% of the total fatty acids. The composition of thetrans‐ and thecis‐octadecenoic acids in the lipids of the mitochondrial membranes was similar for all groups supplemented with sunflower seed oil (SO), irrespective of time and dietary level of partially hydrogenated arachis oil (HAO). Thecis 18∶1 (n−8), which was a major isomer of the partially hydrogenated arachis oil, was almost excluded from the mitochondrial fatty acids. Likewise, the content oftrans 18∶1 (n−8) was considerably lower in the mitochondrial lipids than in the diet. On the contrary, the content oftrans 18∶1 (n−6) was higher in the mitochondrial lipids than in the diet. In the group fed without sunflower seed oil, isomers of linoleic acid and arachidonic acid were observed in the lipids of mitochondrial membranes.
Hydrophilic bile acids: Prevention and dissolution experiments in two animal models of cholesterol cholelithiasis
Authors: Cohen Bertram I. , Mikami Takahiro , Ayyad Nariman , Ohshima Akira , Infante R. , Mosbach Erwin H.
Published: November 2006

The effects of β‐muricholic acid and hyocholic acid on cholesterol cholelithiasis were examined in two animal models. The following experiments were carried out: A) In a gallstone prevention study, prairie dogs were fed the lithogenic diet with or without 0.1% β‐muricholic or 0.1% hyocholic acid for eight weeks. B) In a second prevention study, hamsters were fed the lithogenic diet with or without 0.1% β‐muricholic acid or 0.1% hyocholic acid for six weeks. C) In a gallstone dissolution study, hamsters were fed the lithogenic diet for six weeks to induce stones; stone dissolution was examined during administration of a cholesterol‐free purified diet with or without 0.1% β‐muricholic acid or 0.1% hyocholic acid. In the prevention study in prairie dogs (A), both bile acids failed to prevent stone formation, the cholesterol saturation index of bile was 0.89 in the lithogenic controls, remained unchanged with hyocholic acid and increased to 1.52 in the β‐muricholic acid group. In the prevention study in hamsters (B), β‐muricholic acid completely inhibited the cholesterol cholelithiasis (0% stone incidence); the cholesterol saturation index of bile was 1.78 (compared to lithogenic controls, 1.37). Hyocholic acid reduced stone incidence to 16% with a cholesterol saturation index of 0.98. In the dissolution study in hamsters (C), preexisting cholesterol gallstones were not dissolved by either hydrophilic bile acid after feeding these bile acids for an additional six weeks; at the end of the experiment, the cholesterol saturation indices were below unity. These studies suggest that, in the hamster animal model, hydrophilic bile acids may be useful for the prevention of gallstones but not dissolution of preestablished cholesterol gallstones.
Cyclic fatty esters: Hydroperoxides from autoxidation of methyl 9‐(6‐propyl‐3‐cyclohexenyl)‐(Z)8‐nonenoate
Authors: Awl Richard A. , Frankel Edwin N. , Weisleder David
Published: November 2006

Autoxidation of the cyclic fatty acid ester, methyl 9‐(6‐propyl‐3‐cyclohexenyl)‐(Z)8‐nonenoate (I) was investigated to characterize the hydroperoxide isomers formed and to provide basic information on their chemistry, detection and effect on the quality of polyunsaturated cooking oils. Oxidation at 60 C with 1% hydroperoxide initiator produced a monohydroperoxide fraction containing five positional isomers (7‐, 11‐, 12‐, 13‐ and 14‐OOH), resolved by high performance liquid chromatography, as their allylic hydroxy esters. Their structures were established by1H‐ and13C‐NMR spectroscopy and by capillary gas chromatography‐mass spectrometry (GC‐MS) as trimethylsilyl ether derivatives. Two additional isomers (8‐ and 9‐OOH) were detected by GC‐MS in only trace (<1%) quantities. Capillary GC resolved some geometric and stereoisomers, as well as positional isomers. Compared to photosensitized oxidation, two additional positional isomers (11‐ and 14‐OOH) were produced by autoxidation. More stereoisomers were formed, and oxidation of the ring double bond was favored 8∶1 over that of the side chain. This selectivity may be attributed to greater steric hindrance for oxygen attack at the side‐chain double bond. A free radical mechanism is proposed to explain the greater isomeric complexity of the hydroperoxide products compared to photosensitized oxidation.
Interferon α/β induces changes in the metabolism of polyenoic phospholipids and diacylglycerols in the livers of suckling mice
Authors: Zwingelstein Georges , Brichon Gerard , Meister Roger , Maury Chantal , Gresser Ion
Published: November 2006

Suckling mice were injected daily from birth for 10 days with potent preparations of mouse interferon α/β. Interferon treatment resulted in a markedly lower concentration of polyunsaturated fatty acids (20∶4ω6 and 22∶6ω3) in the two principal liver phospholipids, phosphatidylcholine and phosphatidylethanolamine, than in livers of control‐treated mice. This effect appeared to correlate with a low level of synthesis of polyunsaturated phospholipids in the livers of interferon‐treated mice. Thus, in control mice, synthesis of species of polyunsaturated phospholipids increased markedly in the first 10 days of life, whereas in 10‐day‐old interferontreated mice, the level of synthesis of species of polyunsaturated phospholipids was comparable to that in newborn mice. In parallel, a marked increase in the diacylglycerol content without change of its renewal was observed in the livers of interferon‐treated mice. We suggest that interferon treatment results in an inhibition of one of the processes that leads to activation of the enzymatic systems responsible for the synthesis of species of polyunsaturated phosphatidylcholine and phosphatidylethanolamine in the liver of suckling mice. It seems likely that these results are related to the inhibition of liver cell maturation and the marked cell necrosis that are observed in interferon‐treated suckling mice.
Rapid isolation of microsomes for studies of lipid peroxidation
Authors: Albro Phillip W. , Corbett Jean T. , Schroeder Joanna L.
Published: November 2006

Conventional isolation of microsomes by high‐speed centrifugation from isotonic sucrose requires exposure to air for several hours, leading to the formation of low levels of lipid peroxidation products. Sucrose interferes in protein and malondialdehyde assays and provides no protection against lipid peroxidation during workup. A new procedure for the purification of microsomes from rat liver substitutes mannitol (a hydroxyl radical scavenger) for sucrose and takes advantage of the properties of morpholinopropane sulfonic acid (MOPS) buffer and triethylenetetramine to provide protection against lipid peroxidation during the rapid (less than one hour) workup and subsequent low‐temperature storage. The microsomal fractions prepared by the proposed method are free of detectable mitochondrial contamination and at least as pure overall as those prepared by the conventional method, but they have higher glucose‐6‐phosphatase and laurate hydroxylase activities and significantly less malondialdehyde than conventional microsomes at the time isolation is complete. Laurate hydroxylase activity is more stable during frozen storage in mannitol medium. The kinetics of lipid peroxidation in vitro are quite different for microsomes prepared by the two methods.
A facile synthesis and carbon‐13 nuclear magnetic resonance spectral properties of 7‐ketocholesteryl benzoate
Authors: Parish Edward J. , Wei Tsao‐Yi , Livant Peter
Published: November 2006

This paper presents a modified method of the selective allylic oxidation of cholesteryl benzoate. Pyridinium chlorochromate, in refluxing benzene, has been found to be an effective and convenient reagent for the efficient oxidation of cholesteryl benzoate to 7‐ketocholesteryl benzoate in high yield. Also included herein are the carbon‐13 nuclear magnetic resonance spectral properties of 7‐ketocholesteryl benzoate and cholesteryl benzoate.
Fate of 7,12‐dimethylbenz(a)anthracene absorbed from the rat intestine and transported in chylomicrons
Authors: Lindstrom Mats B. , Barrowman James A. , Borgstrom Bengt
Published: November 2006

Chylomicrons obtained from the thoracic duct of rats fed [3H]7,12‐dimethylbenz(a)anthracene (DMBA), a polycyclic aromatic hydrocarbon, were infused intravenously into rats with bile fistulas. Over 17 hr, 55.9±3.2% (mean ±SEM) of the radioactivity was recovered in bile and 6.7±0.5% in urine. Minor amounts were deposited in liver, kidneys and epididymal fat pads. Injection of DMBA in ethanolic solution gave a similar pattern, while biliary DMBA metabolites resulted in higher recovery in urine and lower recovery in fat. In conclusion, the major part of chylomicron DMBA is rapidly excreted via the biliary route, while a fraction is probably retained in adipose tissue.
Net lipid transfer between lipoproteins in fish‐eye disease plasma supplemented with normal high density lipoproteins
Authors: Holmquist Leif , Carlson Lars A.
Published: November 2006

Native fish‐eye disease plasma, which is deficient of both high density lipoproteins (HDL) and lecithin‐cholesterol acyltransferase activity (α‐LCAT), processing the free cholesterol of these lipoproteins, has been supplemented with normal isolated HDL2 or HDL3 and incubated in vitro at 37 C. After incubation for 0,7.5 and 24 hr the very low density (VLDL) and low density (LDL) lipoproteins as well as HDL were isolated, and their contents of triglycerides, phospholipids and free, esterified and total cholesterol were quantified. The resulting net mass transfer of the different lipids revealed a functioning transfer of cholesteryl esters and all other analyzed lipids between the lipoproteins, although no de novo esterification of the HDL cholesterol by LCAT in this plasma occurred. In accordance with previous findings there was a functioning esterification process of the free cholesterol of the combined VLDL and LDL of fish‐eye disease plasma. The present results make it reasonable to conclude that the lack of HDL cholesterol esterification in this disease is not a result of a deficiency of cholesteryl ester transfer or lipid transfer activities.
Efficacy of linoleic acid administered rectally as monoglyceride
Authors: Christophe Armand , Hill Eidon G. , Holman Ralph T.
Published: November 2006

The potential of the rectal route for administration of essential fatty acids (EFA) as monoglyceride (MG) was investigated. EFA‐deficient rats were supplemented with 14 mg linoleic acid/day for 3 days. Supplementation was either by oral administration as corn oil, orally as corn oil‐derived MG or rectally as MG. The patterns of polyunsaturated fatty acids (PUFA) in liver and serum lipids, characteristic of EFA deficiency, were altered in the direction of normalcy in similar magnitude by all modes of supplementation, indicating that the rectal route may be useful for administration of EFA. The amounts of phospholipids (PL) and free fatty acids (FFA) in liver changed by all modes of administration. The magnitude of change of total PL and of FFA in liver depended upon the chemical form in which linoleic acid was administered and the route of administration, indicating that these factors affect lipid metabolism.
The influence of dietary fat on the lipogenic activity and fatty acid composition of rat white adipose tissue
Authors: Nelson Gary J. , Kelley Darshan S. , Schmidt Perla C. , Serrato Claire M.
Published: November 2006

The in vivo fatty acid synthesis rate, selected enzyme activities and fatty acid composition of rat white adipose tissue from animals fed semisynthetic diets of differing fat type and content were studied. All animals were starved for 48 hr and then refed a fat‐free (FF) diet for 48 hr. They were then divided into three groups. One group was continued on the FF diet for 48 hr. Another group was fed a diet containing 44% of calories from corn oil (CO). The final group was fed a diet containing 44% of calories from completely hydrogenated soybean oil (HSO). The animals on the FF diet had a marked increase in adipose tissue fatty acid synthesis during the 96‐hr feeding peroid (as measured by3H incorporation into adipose fatty acids). Addition of either CO or HSO to the diets did not significantly inhibit fatty acid synthesis in dorsal or epididymal adipose tissue. The activities of the enzymes' fatty acid synthetase, ATP‐citrate lyase and glucose‐6‐phosphate dehydrogenase increased on the FF diet and generally were not inhibited significantly by the addition of either fat to the diets. Linoleic acid was the major polyunsaturated fatty acid (ca. 22%) in adipose tissue. Monounsaturated fatty acids (palmitoleic, oleic,cis‐vaccenic) made up ca 38% of the total adipose fatty acids, while saturated fatty acids accounted for about 32% (myristic, palmitic and stearic). White adipose tissue in mature male rats was a major depot for n−3 fatty acids. There were differences in the fatty acid composition of epididymal and dorsal adipose tissue, particularly in their content of long chain, polyunsaturated fatty acids with epididymal tissue containing more of these compounds than dorsal fat. The fatty acid composition of the white adipose tissue did not change significantly during fasting or 96 hr of refeeding the FF diets. The addition of HSO to the diet for 48 hr had little influence on the adipose tissue fatty acid composition, but the addition of CO to the diet caused a 7% increase in the dorsal adipose tissue linoleate content (as percentage of total dorsal adipose tissue fatty acids) within 48 hr compared to animals fed the stock diet and those starved for 48 hr. The fatty acid synthesis data indicated that adipose tissue in the rat can continue to be a source of de novo fatty acid synthesis in animals consuming high‐fat diets.
Hepatic Δ9 and Δ6 desaturase activities during the recovery period following carbon tetrachloride poisoningdesaturase activities during the recovery period following carbon tetrachloride poisoning
Authors: Carreau Jean‐Paul , Frommel Dominique , Nguyen Thi Thé , Mazliak Paul
Published: November 2006

The liver microsomal Δ9 and Δ6 desaturase activities have been studied in rats with carbon tetrachloride‐induced hepatitis. Immediately after poisoning, significant decreases were observed for both types of desaturase activity. However, recovery kinetics were slower for the Δ6 desaturase than for the Δ9 desaturase. The activities of NADH‐ferricyanide and NADH‐cytochrome C reductases, proteins involved in the electron transfers associated with microsomal desaturation, were also measured. There was a fall in both activities after poisoning, but this decrease was less than that of the desaturase activities.
Analysis of autoxidized fats by gas chromatography‐mass spectrometry: VI. Methyl 9,15‐ and 12,15‐octadecadienoate
Authors: Frankel E. N. , Dufek E. J. , Neff W. E.
Published: November 2006

The gas chromatography‐mass spectrometry (GC‐MS) method developed in preceding papers was extended to the structural analysis of autoxidation products of methylcis‐9,cis‐15‐octadecadienoate and of an 87% concentrate ofcis‐12,cis‐15‐octadecadienoate. Eight isomeric hydroxydienes with one allylic and one isolated double bond were identified from oxidized 9,15‐diene and 2 conjugated hydroxydienes from oxidized 12,15‐diene, after reduction of the hydroperoxides. The proportions of 16‐(15%) and 17‐hydroperoxides (22%) from 9,15‐diene were significantly higher than that of the other isomers (8–12% each: 8‐, 9‐, 10‐, 11‐, 14‐ and 15‐OOH). Similarly, the amount of 16‐hydroperoxide from 12,15‐diene was larger (42%) than the 12‐hydroperoxide (31%). Substantial amounts of dihydroxy esters with one OH substituent on carbons‐8,‐9,‐10 or‐11 and the other OH on carbons‐14,‐16 or‐17, were identified after hydrogenation in highly oxidized 9,15‐diene. The implications of these hydroperoxide analyses are discussed in relationship to the precursors of flavor deterioration of oils and partially hydrogenated oils containing an ω‐3 double bond.
Preparation of radiolabeled tetracosa mono‐ and dienoic acid methyl esters from rat erythrocyte lipids by thin layer chromatography
Authors: Rao G. Ananda , Kilpatrick Robert L. , Goheen Steven C. , Larkin Edward C.
Published: November 2006

An easy method of obtaining pure fatty acid methyl esters (FAME) of tetracosa mono‐ and dienoic acids (24∶1, 24∶2) using thin layer chromatography (TLC) is described. The total lipids isolated from rat erythrocytes were treated with methanolic‐NaOH. Sphingomyelin was unaffected by this treatment and was separated from FAME of glycerolipids and cholesterol by TLC. FAME of sphingomyelin were then prepared by acid methanolysis. These esters migrated into 2 distinct bands on TLC. The slow moving band contained FAME of 16∶0, 16∶1, 18∶0, 18∶1, 19∶0 and 20∶0 whereas the fast moving band contained FAME of 22∶0, 23∶0, 24∶0, 24∶1 and 24∶2. After AgNO3‐TLC, the FAME of the fast moving band separated into 3 species; esters of saturated acids, 24∶1 and 24∶2, respectively. With erythrocyte lipids of rats fed a fat‐free diet and injected with14C‐18∶1, this method yielded14C‐24∶1. From rats injected with14C‐18∶2 and maintained on a corn oil diet,14C‐24∶2 was obtained.
The Δ5 and Δ6 desaturation of fatty acids of varying chain length by rat liver: A preliminary report
Authors: Pollard Michael R. , Gunstone Frank D. , Morris Lindsay J. , James Anthony T.
Published: November 2006

The Δ6 desaturase of rat liver can accommodate substrates with a wide range of chain lengths. Δ9‐cis,12‐cis‐Dienoic acids of chain lengths 14–22 carbon atoms were all desaturated at the Δ6 position by microsomal preparations from rat liver. By contrast, the Δ5 desaturase appeared much more chain‐length sensitive. The percentage Δ5 desaturation of a series of Δ8‐cis‐ and Δ9‐trans‐monoenoic acids increased with increasing chain length (from C16 to C20).
Techniques for the isolation and identification of steroids in insects and algae
Authors: Thompson Malcolm J. , Patterson Glen W. , Dutky Samson R. , Svoboda James A. , Kaplanis John N.
Published: November 2006

Analytical techniques, methods and instrumentation employed for the extraction, isolation separation, purification and identification of steroids from algae and insects are presented. The techniques include adsorption and argentation column chromatography and counter‐current distribution for separating the individual steroids, and thin layer chromatography and gas liquid chromatography for monitoring the purification process. Double bond, steric and alkyl substituent separation factors and relative retention times are reported for a large number of sterols on 4 different column systems. Their use permits the tentative structural assignment of sterols. Ultraviolet, infrared, nuclear magnetic resonance (NMR) and mass spectral analyses are discussed in light of their significance in the isolation and identification of steroids from insects and algae. Numerous examples are presented, including the use of 220 MHz NMR spectrometry, which permits the differentiation and characterization of C‐24 epimetric sterols and allows for a semiquantitative estimate of the 24α‐ and 24β‐epimers present in a mixture.
Identification of sterols and bile acids by computerized gas chromatography‐mass spectrometry
Authors: Elliott William H.
Published: November 2006

In mass spectrometry, sterols and bile acids form fragment ions characteristic of certain steroid structures. After separation of derivatized sterols or bile acids by the gas chromatograph and fragmentation in the mass spectrometer, data collected by the computer can be collated to provide a reconstructed gas chromatogram and a series of fragment ion current chromatograms in which the relative abundances of characteristic fragment ions are plotted vs time or scan number. Intensities of these fragment ions will be greatest and hence coincide with peak elution of unidentified sterols or bile acids. The use of known amounts of labeled appropriate sterols or bile acids permits quantitation of the identified sterol or bile acid.
Determination of molecular formula and stereoconfiguration of unique steroids by X‐ray diffraction analysis
Authors: Karle Jerome
Published: November 2006

X‐Ray diffraction analyses can determine chemical composition, molecular formula and stereoconfiguration and can provide geometric parameters with uncertainties for bond distances of the order of 0.01 Å and for bond angles of the order of 1°. These analyses are especially useful when the substance analyzed is present only in very small quantities and is of uncertain composition or molecular formula. Only one suitable crystal is required for the analysis to proceed. There are many instances in which such circumstances have prevailed in the diffraction analysis of steroids. Among the examples given here is a new type of natural plant hormone with profound growth‐stimulating capabilities when applied in nanogram quantities per plant. The structure determination of this substance has greatly facilitated attempts to synthesize it and thereby to derive sufficient quantities for widespread testing.
Effect of diet on choline phosphotransferase, phosphatidylethanolamine methyltransferase and phosphatidyldimethylethanolamine methyltransferase in liver microsomes
Authors: Hoffman Dennis R. , Uthus Eric O. , Cornatzer W. E.
Published: November 2006

Phosphatidylcholine (PC) biosynthesis has been investigated in female rats fed a liquid amino acid, choline‐methionine‐free diet by assaying in liver microsomes the specific and total activities of choline phosphotransferase, phosphatidyldimethylethanolamine methyltransferase and phosphatidylethanolamine methyltransferase. There was a significant decrease in the specific activity (sp act) of choline phosphotransferase in the liver of rats fed a choline‐methionine‐free diet. The dietary omission of methionine for 2 wk resulted in a significant decrease in the sp act of choline phosphotransferase. The dietary omission of choline, methionine, B12, folic acid and the addition of a methyl group acceptor, guanidoacetic acid, decreased further the sp act of choline phosphotransferase. The phosphatidyl‐ethanolamine methyltransferase sp act increased with the dietary omission of choline and methionine. The dietary omission of choline, methionine, B12, folic acid and the addition of a methyl group acceptor, guanidoacetic acid, resulted in a decrease in the sp act of phosphatidyldimethylethanolamine methyltransferase and an increase in phosphatidylethanolamine methyltransferase. The dietary omission of choline, methionine, B12, folic acid and the addition of a methylation inhibitor, 2‐amino‐2‐methyl‐1‐propanol, did not result in a significant decrease in the sp act of choline phosphotransferase; however, it did significantly decrease the sp act of phosphatidylethanolamine methyltransferase. The addition of dietary methionine with the inhibitor resulted in a significant decrease in the sp act of the choline phosphotransferase and phosphatidylethanolamine methyltransferase when compared to control and/or when compared to deficient with or without inhibitor. The dietary supply of methionine, as a source of choline, did affect the activity of the enzymes that synthesize PC. The ratio of the substrate, S‐adenosylmethionine, and the inhibitory product, S‐adenosylhomocysteine, affected the enzymatic activity of phosphatidylethanolamine methyltransferase. It is suggested that the concentrations of these 2 compounds may be important in regulating the methylation of phosphatidylethanolamine in the liver cell.
Synthesis of α‐hydroxy stearyl coenzyme A
Authors: Chauhan M. S. , Dakshinamurti K.
Published: November 2006

Synthesis of α‐hydroxy stearyl CoA from N‐hydroxysuccinimide ester of a α‐hydroxy stearic acid and coenzyme A is reported. The CoA derivative has been isolated, purified and characterized from its spectral data and chemical properties.