bluuebunny/crossref_metadata_2025 huggingface dataset:
Stearoyl‐coenzyme a desaturase activity in the mammary gland and liver of lactating rats
Authors: Calabro Michael A. , Prasad M. Renuka , Wakil Salih J. , Joshi Vasudev C.
Published: December 2006

Stearoyl‐CoA desaturase activity in microsomes from lactating rat mammary gland is very low (0.05–0.15 nmol/min/mg of protein) regardless of lactating time. In such microsomes, reductase activities and content of cytochrome b5 are several‐fold lower than in normal rat liver microsomes. Preincubation of the mammary microsomes with purified terminal desaturase gives a 55‐fold stimulation of stearoyl‐CoA desaturase activity, whereas preincubation with cytochrome b5 has no effect. However, preincubation of mammary microsomes with both cytochrome b5 and terminal desaturase results in a 200‐fold stimulation of overall desaturation. These observations suggest that negligible stearoyl‐CoA desaturase activity in lactating rat mammary microsomes is due to a low cytochrome b5 content and the absence of terminal enzyme. The hepatic stearoyl‐CoA desaturase activity increases 9‐fold during lactation. There is little or no change in the NADH‐cytochrome c reductase activity or in the concentration of cytochrome b5 during this period, but the activity of the terminal desaturase increases with the increase of overall desaturation. These results suggest that liver is one of the more important sources of oleic acid for milk triglycerides.
Autoxidation of phosphatidylcholine liposomes
Authors: Wu Guey‐Shuang , Stein Robert A. , Mead James F.
Published: December 2006

Autoxidation of pure soybean phosphatidylcholine liposomes at 40 C was found to proceed without an observed induction period, but otherwise, the rates of disappearance of the linoleic acid (70% of total) and linolenic acid (6% of total) followed typical autocatalytic kinetics. Incorporation of 0.05 mol % of tocopherol into the liposomes produced an induction period of about 7 hr under the condition used for the incubation. The produts formed from the autoxidation of pure soybean phosphatidylcholine liposomes were mostly 9‐ and 13‐hydroperoxyoctadecadienoates (isolated as hydroxy esters). The yield of hydroperoxides withcis,trans configuration was about the same as those withtrans,trans configuration throughout incubation period. After extensive autoxidation, a large quantity of trihy droxyoctadecenoate was also produced. When a large quantity of dipalmitoyl phosphatidylcholine was incorporated into soybean phosphatidylcholine liposomes, the rate of autoxidation decreased and was found to conform to apparent first‐order kinetics. In this system, the yield oftrans, trans hydroperoxides was much greater than that ofcis,trans isomers at all stages of autoxidation. Late in the autoxidation of the mixed liposomes, both trihydroxyoctadecenoate and hydroxyepoxyoctadecenoate were produced in substantial quantities.
Development of the diurnal rhythm of chick 3‐hydroxy‐3‐methylglutaryl‐CoA reductase
Authors: Ramirez H. , Alejandre M. J. , Garcia‐Peregrin E.
Published: December 2006

Chick liver and intestine 3‐hydroxy‐3‐methylglutaryl‐CoA reductase did not show diurnal rhythm at hatching. Differences in activity between light and dark periods appeared during the first week and remained more or less constant between 10–14 days after hatching. Hepatic and intestinal reductase activities were maximal during the light period and minimal during the dark period. Amplitude of the rhythm was practically similar in both tissues (about 3‐fold) although specific activities and differences between peak and nadir values were always higher in liver. Chick brain reductase did not show significant diurnal variations in the age range assayed.
Positional distribution of fatty acids in triglycerides from milk of several species of mammals
Authors: Parodi Peter W.
Published: December 2006

Milk triglycerides from the echidna, koala, Tammar wallaby, guinea pig, dog, cat, Weddell seal, horse, pig and cow were subjected to fatty acid and stereospecific analysis to determine the positional distribution of the fatty acids in the triglycerides. The samples presented a wide range of fatty acids, most of which varied in content among species. The compositions of the acids at the 3 positions also varied among species, reflecting the content of these acids in the triglycerides. However, there was a general similarity in fatty acid positional distribution patterns for all the species with the exception of the echidna. The echidna exhibited a completely different fatty acid positional distribution pattern. The saturated acids were preferentially esterified at thesn‐1‐position whereas the unsaturated acids were selectively esterified at thesn‐2‐position. The triglyceride carbon number distribution of milk from the above species (with the exception of the Weddell seal) was determined by gas liquid chromatography and compared to that predicted by the 1‐random‐2‐random‐3‐random fatty acid distribution hypothesis. Agreement was excellent between observed and predicted composition for echidna, koala, Tammar wallaby, guinea pig and pig milk, and agreement was reasonable for dog, cat, horse and cow milk. Results are discussed in relation to biochemical mechanisms.
Digitonide precipitable sterols: A reevaluation with special attention to lanosterol
Authors: Cenedella Richard J.
Published: December 2006

The ability of digitonin to precipitate lanosterol from prepared mixtures and biological sources was evaluated. Commercially available lanosterol was determined to be composed of about 60% lanosterol and 40% dihydrolanosterol. Both sterols were only partially precipitated by digitonin under all conditions examined. The presence of cholesterol increased the precipitation of lanosterol, but never to completion. About 40% of the lanosterols from saponified sheep's‐wool fat was not precipitated by digitonin. Also14C‐labeled lanosterol recovered from rat brain following intracerebral injection of 2‐[14C] mevalonate was only 70% precipitated by digitonin. Steric hinderance by the methyl groups at carbon −4 is suggested to explain the poor precipitability of this sterol. In conclusion, lanosterol can not be considered to be a digitonide‐precipitable sterol equivalent to cholesterol. Caution should be exercised in situations where digitonin‐precipitable sterols are being prepared from sources containing significant concentrations of lanosterol (i.e., mass and/or radiolabel).
Determination of cholesteryl esters and of cholesteryl and epicholesteryl silyl ethers by capillary gas chromatography
Authors: Smith Norman B.
Published: December 2006

The capillary gas chromatography of cholesteryl esters after splitless injection into a 25‐m, OV‐1‐coated, fused silica WCOT column and a 7‐m Silar 10C‐coated glass WCOT column is reported. The nonpolar OV‐1 column separated the cholesteryl esters principally on the basis of carbon number, but separation of the saturated esters from the unsaturated esters was also achieved. The polar Silar 10C column separated the esters mainly according to the degree of unsaturation. Thus, the 2 column types complement each other in the analysis of nanogram quantities of cholesteryl esters from small samples, such as those from plasma or single arterial atherosclerosis lesions. This technique therefore obviates some of the difficulties of analyzing such cholesteryl ester samples in the form of methyl esters (incomplete transmethylation, and contamination by solvent impurities and/or plasticizer esters). Both columns were also found to be useful for the separation and quantitaiton of thet‐BDMS ethers of cholesterol and epicholesterol in mixtures containing various proportions of these epimers.
Saturated fatty acids >C20 are not activated by acid:CoA ligase in rat brain or liver?
Authors: Murphy Mary G. , Spence Matthew W.
Published: December 2006

The formation of long‐chain saturated acyl‐[3H]CoA and [1‐14C] acyl‐[3H]CoA by rat brain microsomes and rat liver was examined. Acyl‐CoA formation was markedly decreased as fatty‐acid chain length increased from C16 to C20. No biosynthesis of behenyl‐[3H] CoA or [1‐14C] lignoceryl‐[3H] CoA was observed. The results suggest that long‐chain saturated fatty acids >20 carbons in length are not activated by acid:CoA ligase to form acyl‐CoA.
ω‐ and (ω‐1)‐hydroxylation of 1‐dodecanol by frog liver microsomes
Authors: Miura Yoshiro
Published: December 2006

Frog liver microsomes catalyzed the hydroxylation of 1‐dodecanol into the corresponding ω‐ and (ω‐1)‐hydroxy derivatives. The hydroxylation rate for 1‐dodecanol was much lower than that for lauric acid. Both NADPH and O2 were required for hydroxylation activity. NADH had no effect on the hydroxylation. The hydroxylating system was inhibited 49% by CO at a CO∶O2 ratio of 4.0. The formation of ω‐hydroxydodecanol was more sharply inhibited by CO than was the formation of (ω‐1)‐hydroxydodecanol, implying that more than one cytochrome P‐450 was involved in the hydroxylation of 1‐dodecanol and that CO has a higher affinity for the P‐450 catalyzing the ω‐hydroxylation. The formation of laurate during the incubation of 1‐dodecanol with frog liver microsomes suggests that a fatty alcohol oxidation system is also present in the microsomes. NAD+ was the most effective cofactor for the oxidation of 1‐dodecanol and NADP+ had a little effect. Pyrazole (an inhibitor of alcohol dehydrogenase) had a slight inhibitory effect on the oxidation and sodium azide (an inhibitor of catalase) had no effect.
Desaturation of endogenous and exogenous palmitate in lung tissue in vitro
Authors: Balint John A. , Kyriakides Emilios C. , Beeler Donald A.
Published: December 2006

Lung slices from rats fed a fat‐free diet supplemented with safflower oil (control) or tripalmitoyl‐glycerol (essential fatty acid [EFA]‐deficient) were incubated with [14C] acetate, [14C] palmitate, or [14C] stearate. Of the14C recovered in phospholipids after incubation with [14C] acetate, more than 87% was in 16‐carbon fatty acids. Desaturation, as assayed by the percentage of radioactivity in monoenoates in phospholipid fatty acids, was generally double in EFA‐deficient slices compared to control slices, regardless of substrate. Desaturation was significantly greater in slices incubated with acetate or octanoate compared to palmitate, indicating that endogenously synthesized palmitate was desaturated more actively than that derived from an exogenous source.
Zinc deficiency increases the rate of Δ6 desaturation of linoleic acid in rat mammary tissue
Authors: Cunnane S. C. , Wahle K. W. J.
Published: December 2006

The effect of zinc deficiency on the Δ6‐desaturation of [1‐14C] linoleic acid was studied in mammary tissue microsomes from lactating rats. The rats were maintained on zinc‐adequate (20 ppm zinc) or zinc‐deficient (10 ppm zinc changing to 0.5 ppm zinc during last trimester) diets throughout gestation and for the first 3 days of lactation. Mammary tissue microsomes were incubated with [1‐14C] linoleic acid and other samples of mammary tissue, mammary milk and the milk in the stomachs of the pups were analyzed for total fatty acid composition. In mammary microsomes from zinc‐deficient rats, Δ6‐desaturation of linoleic acid was 3.4 times greater than in microsomes from zinc‐adequate rats. This change in metabolism of linoleic acid was reflected by comparable changes in the relative tissue and milk composition of linoleic and arachidonic acids and in the ratios of palmitic to palmitoleic acid, stearic to oleic acid and linoleic and arachidonic acid.
Anatomical distribution of sterols in oysters (Crassostrea gigas)
Authors: Gordon Dennis T. , Collins Nancy
Published: December 2006

Oysters (Crassostrea gigas) contain at least 8 predominant sterols as determined by gas liquid chromatography and a modified Liebermann‐Burchard reaction. These sterols and the average amount found in mg/100 are: C26‐sterol (22‐trans‐24‐norcholesta‐5, 22‐diene‐3β‐ol), 19.1; 22‐dehydrocholesterol, 15.1; cholesterol, 46.8; brassicasterol, 27.2; Δ5,7‐sterols (i.e., 7‐dehydrocholesterol) 22.5; 24‐methylenecholesterol 29.1; 24‐ethylcholesta‐5,22‐diene‐3β‐ol, 1.2; and 24‐ethylcholesta‐5‐en‐3β‐ol, 12.7. The distribution of these sterols appears uniform (r2=0.938) between 5 major organs of the oyster. The percent body mass vs percent total sterols in these 5 organs are: mantle 44.1–41.4; visceral mass 30.3–36.7; gills 13.2–11.7; adductor muscle 8.3–3.7; and labial palps 4.2–6.5. The possible sources of these sterols are discussed.
Phospholipid studies of marine organisms: III. New phospholipid fatty acids fromPetrosia ficiformis
Authors: Ayanoglu Eser , Walkup Robert D. , Sica Donato , Djerassi Carl
Published: December 2006

The fatty acyl components of the phospholipids from the spongePetrosia ficiformis consisted predominantly of branched, especially iso and anteiso acids. The two major components of the complex mixture are the hitherto unknown Z,Z‐25‐methyl‐5,9‐hexacosadienoic and Z,Z‐24‐methyl‐5,9‐hexacosadienoic acids. Other unknown acids are: 7,13,16‐docosatrienoic acid, 15‐methyldocosanoic acid, 15‐methyltricosanoic acid and 24‐methyl‐5,9‐pentacosadienoic acid. Short branched‐chain fatty acids, presumably of bacterial origin, are considered to be the possible bioprecursors of these novel phospholipid constituents. The major phospholipids were PE, PC, PG, PS and PI. The distribution of fatty acids among the phospholipid classes was also studied.
Isolation and determination of cholesterol glucuronide in human liver
Authors: Hara Atsushi , Taketomi Tamotsu
Published: December 2006

Separation of the acidic lipid fraction from human liver led to the identification of cholesterol‐β‐glucuronide for the first time from this organ. Cholesterol glucuronide was purified by DEAE‐Sephadex column chromatography and preparative silica gel thin‐layer chromatography. The content in normal human liver was about 33 nmol/g wet tissue. It must be emphasized that cholesterol glucuronide cannot be distinguished readily from ganglioside GM4 by thin‐layer chromatography.
Uptake and metabolism of free fatty acids by the morris 7777 hepatoma and host rat liver
Authors: Morton Richard E. , Waite Moseley , Lynn King V. , Morris Harold P.
Published: December 2006

The relative capacity of Morris 7777 hepatomas and livers of tumor‐bearing rats to take up and subsequently metabolize intravenously injected radiolabeled free fatty acids was investigated. The objective was to determine differences in lipid metabolism which may affect the lipid composition previously observed in this tumor. Both tissues demonstrated comparable selectivity in the uptake of palmitate, linoleate and arachidonate from blood, although the hepatoma took up one‐tenth as much free fatty acid per g wet wt as liver. A much greater percentage of fatty acid taken up by the hepatoma was converted to aqueous soluble radioactivity, perhaps the result of oxidation. In the hepatoma, palmitate was incorporated into phospholipid molecular species in a pattern similar to that observed for diglyceride, which suggested that phospholipid synthesis occurred predominantly de novo. On the other hand, in liver, a large percentage of palmitate was incorporated into polyunsaturated phospholipid molecular species that were not present in the diglyceride pool, which suggested significant incorporation by the acylation of monoacyl phosphoglycerides. These studies indicate that the specificity for the uptake of fatty acids was not different in the two tissues; however, the subsequent metabolic processes are markedly different.
13C nuclear magnetic resonance spectroscopic analysis of seed oils containing conjugated unsaturated acids
Authors: Tulloch A. P.
Published: December 2006

13C Nuclear magnetic resonance spectroscopy has been used in a nondestructive investigation of conjugated unsaturated acids in seed oil triacylglycerols. Spectra of seven seed oils, fromPunica granatum, Cucurbita palmata, Jacaranda mimosifolia, Centranthus ruber, Catalpa bignonioides, Chilopsis linearis andCalendula officinalis, containing among them six isomeric trienoic acids,cis,trans,cis‐ andtrans,trans,cis‐8,10,12‐,cis,trans,cis‐, cis,trans,trans‐, trans,trans,cis‐ andtrans,trans,trans‐9,11,13‐octadecatrienoic acids, and of the oil ofImpatiens balsamina containingcis,trans,trans,cis‐9,11,13,15‐octadecatetraenoic acid, have been examined. Structures of component acids were derived from shifts of double bond carbons and of carbons close to the double bond systems. Compositions of the oils were obtained from signal intensities. Results were similar to those obtained by older methods. Only oil ofCentranthus ruber contained more than one major conjugated acid; bothcis,trans,trans‐ andtrans,trans,trans‐9,11,13‐octadecatrienoic acids were found. The latter acid is now thought to occur naturally.
Enzymatic hydrolysis of fractionated products from oils thermally oxidized in the laboratory
Authors: Yoshida Hiromi , Alexander J. C.
Published: December 2006

Enzymatic hydrolysis of the acylglycerol products obtained from thermally oxidized vegetable oils was studied. Corn, sunflower and soybean oils were heated in the laboratory at 180 C for 50, 70 and 100 hr with aeration and directly fractionated by silicic acid column chromatography. By successive elution with 20%, then 60% isopropyl ether inn‐hexane, and diethyl ether, the thermally oxidized oils were separated into three fractions: the nonpolar fraction (monomeric compounds), slightly polar fraction (dimeric compounds), and polar fraction comprising oligomeric compounds. Enzymatic hydrolysis with pancreatic lipase showed that the monomers were hydrolyzed as rapidly as the corresponding unheated oils, the dimers much more slowly, and the oligomeric compounds barely at all. Overall, the hydrolysis of the dimers was less than 23% of that for the monomers, with small differences among the oils. Longer heating periods resulted in greater reductions in hydrolysis of the dimeric compounds. These results suggest that the degree of enzymatic hydrolysis of the fractionated acylglycerol compounds is related to differences in the thermal oxidative deterioration, and amounts of polar compounds in the products.
Metabolism of sterols by anaerobicSaccharomyces cerevisiae
Authors: Sekula Bernard C. , Nes William R.
Published: December 2006

Anaerobically grownSaccharomyces cerevisiae retained the ability to transfer a C1‐group to the C‐24 position of a Δ24(25)‐sterol and to reduce the Δ24(28)‐bond of a 24‐methylenesterol. Both desmosterol and 24‐methylenecholesterol yielded 24β‐methylcholesterol. However, when the substituent at C‐24 was enlarged to a 24‐ethylidene group (fucosterol), reduction of the Δ24(28)‐bond did not occur. In no cases was a Δ7 a Δ22‐bond introduced. Because the Δ24(28)‐bond was, reduced in the absence of the Δ22‐bond the Δ22 is not an obligatory requirement for reduction.
Suppression of hepatocyte fatty acid synthesis by albumin‐bound linoleate involves depolymerization of acetyl‐CoA carboxylase filaments
Authors: Clarke Steven D. , Hillard Bruce L.
Published: December 2006

Digitonin treatment of chick liver cells in monolayer culture results in plasma membrane perforations due to digitonin removal of membrane cholesterol. The amount and rate of acetyl‐CoA carboxylase activity that escapes from the hepatocyte during digitonin treatment is positively related to the amount of protomeric carboxylase in the cells. Incubation of chick liver cells in culture with albuminbound linoleate (60 min) caused a 3‐fold increase in the amount of carboxylase activity released during exposure of cells to digitonin. Concomitant with the enhanced release of carboxylase activity was an 85% reduction in fatty acid synthesis induced by linoleate. Apparently, acute suppression of hepatocyte fatty acid synthesis by media free fatty acids resulted, in part, from a change in carboxylase conformation from the active polymeric state to the inactive protomeric form.
Interrelationship between the dietary regulation of fatty acid synthesis and the fatty acyl‐CoA desaturases
Authors: Jeffcoat R. , James A. T.
Published: December 2006

In this paper we present further evidence for the close control of fatty acid synthetase and stearoyl‐CoA desaturase. Furthermore, we have established that whereas dietary palmitic acid may influence the activity of this desaturase but not of fatty acid synthetase, dietary linoleic acid appears to control both these enzymes. Finally, we have studied the influence of dietary fat and carbohydrate on the activities of the Δ6 and Δ5 desaturases. The former is only slightly affected by these dietary components. The Δ5 desaturase activity is stimulated as the dietary fat content rises but is un‐affected by dietary carbohydrate. The control of these enzymes is therefore independent of the control of fatty acid synthetase and stearoyl‐CoA desaturase. From the data presented, the magnitude of the controlling effect of polyunsaturated fatty acids on fatty acid synthetase and stearoyl‐CoA desaturase activity is determined and its relevance to lipogenesis in man based on daily intake of carbohydrate and linoleic acid is discussed.
Analysis of oleate and linoleate hydroperoxides in oxidized ester mixtures
Authors: Wong Wing‐sum Dominic , Hammond E. G.
Published: December 2006

The hydroperoxides in oxidized mixtures of methyl oleate and linoleate were reduced to the corresponding hydroxyesters, which were separated from unoxidized esters by thin layer chromatography on silica gel. The hydroxyesters from oleate and linoleate were converted to trimethylsilyl ethers and separated by gas chromatography on OV 225. The results suggest that methyl linoleate oxidizes about ten times faster than methyl oleate, but oleate hydroperoxides are formed in appreciable amounts, even in mixtures containing 87% methyl linoleate.
Studies on the inhibition of the desaturases by cyclopropenoid fatty acids
Authors: Jeffcoat R. , Pollard M. R.
Published: December 2006

Unwashed rat liver microsomes were used to study the inhibition of the Δ6 and Δ9 desaturases by cyclopropenoid fatty acids with the ring structure about the 9,10 or 6,7 carbon atoms. The 9,10 cyclopropenoid acid (sterculic acid) is shown to be an effective inhibitor of only Δ9 desaturase and then only in the presence of MgCl2 and coenzyme A (prepresence of MgCl2 and coenzyme A (presumably due to the formation of sterculoyl‐CoA). Two 6,7 cyclopropenoid acids of different chain lengths showed no marked inhibition of either the Δ6 or Δ9 desaturase. By the use of [3H]‐sterculic acid, it has been shown that under conditions of high inhibition of the Δ9 desaturase the inhibitor is not covalently attached to the enzyme at any point. This disproves older ideas on the mechanism of inhibition that assumed reaction between the cyclopropenoid ring and sulphydryl groups on the enzymes.
The effect of various dietary factors on the size distribution of lymph fat particles in rat
Authors: Boquillon Micheline , Paris Roger , Clement Jacqueline
Published: December 2006

By means of cellulose acetate electrophoresis and measurement of radioactivity, lipoproteins (d≤1,006) of lymph collected from rats fed a diet containing fats added to labeled fatty acids for 20–24 hr, have been separated into two kinds differing in their size. Fats with different saturated and unsaturated fatty acid content were tested: corn oil, lard, mutton tallow, tripalmitin, corn oil‐lard mixture, and randomized palmitic‐linoleic triglycerides. Factors studied were: (a) increased amounts of these fats given alone or included in a test meal; (b) added amounts of nutrients (other than fats) in the test meal; (c) adaptation to a diet containing 20% fat for 10 days. The major part of the labeled lymph lipid was always transported by the smaller particles. Size distribution of lymph fat particles was influenced by some of the factors studied. Generally, unsaturated fats produced higher amounts of larger particles.
Thiobarbituric acid reaction of methyl arachidonate monohydroperoxide isomers
Authors: Terao J. , Matsushita S.
Published: December 2006

Methyl ester of monohydroperoxy eicosatetraenoic acid (MeHPETE) was prepared from methylene blue sensitized photooxidation products of methyl arachidonate. The thiobarbituric acid (TBA) value of MeHPETE was increased by adding ferrous sulfate to the reaction mixture. A linear relationship existed betweent he TBA value and the concentration of MeHPETE when ferrous sulfate was added. By using high performance liquid chromatography, MeHPETE was separated into 5 fractions whose isomeric compositions were determined by gas chromatography‐mass spectrometry. The results of the TBA test for each fraction suggest that all of the MeHPETE isomers are positive to the TBA test. It is concluded that each isomer of HPETE formed by peroxidation of arachidonic acid in a biological system can yield TBA‐reacting materials during the test reaction.
The effect of different proportions of casein in semipurified diets on the concentration of serum cholesterol and the lipoprotein composition in rabbits
Authors: Terpstra A. H. M. , Harkes L. , van der Veen F. H.
Published: December 2006

The effect of different proportions of casein in semipurified diets on the concentation of serum cholesterol and the lipoprotein composition was studied in rabbits. Low‐casein diets (10% w/w) resulted in serum cholesterol levels and growth rates that were lower than high‐casein diets (40%). An intermediate proportion of casein (20%) produced intermediate concentrations ofserum cholesterol, but only minor differences in food intake and weight gain, compared with the high‐casein group. In the animals with the highest values of total serum cholesterol (the 40% casein group), most of the serum cholesterol was transported in the very low density lipoproteins, whereas with moderate hypercholesterolemia (the 20% casein group), the low density lipoproteins were the main carriers of cholesterol. Elevation in lipoprotein cholesterol was associated in all groups with an increased ratio of cholesterol to protein, suggesting the formation of particles relatively rich in cholesterol. When the rabbits on the diet containing 10% casein were subsequently transferred to the 40% casein diet, a steep increase in the level of serum cholesterol occurred. Conversely, switching the rabbits on the 40% casein diet to the 10% casein diet resulted in a decrease in the level of serum cholesterol.
A lysosomal enzyme involved in diphosphatidylglycerol degradation
Authors: Werchola George Michael , Mellors Alan
Published: December 2006

A soluble lysosomal phosphodiesterase in rat liver that hydrolyzes monoacyglycerophosphoryl‐glycerophosphorylglycerol (AGPGPGase) was shown to be distinct from a lysosomal acid phosphodiesterase IV (PDase IV) which catalyzes the hydrolysis of bis(p‐nitrophenyl) phosphate. The criteria used to distinguish lysosomal AGPGPGase from PDase IV were: separation on ion exchange celluloses, dissimilar inhibition patterns and different rates of inactivation on concentration. The lysosomal PDase IV activity was competitively inhibited by inorganic phosphate with a Ki value of 0.33 mM phosphate and was inhibited by a number of organophosphoryl compounds including AGPGPG, phosphatidylcholine, phosphatidylinositol, ATP and 4‐methylum belliferylpyrophosphate.
Stereospecific analysis of fatty acid esters of chloropropanediol isolated from fresh goat milk
Authors: Myher J. J. , Kuksis A. , Marai L. , Cerbulis J.
Published: December 2006

The fatty acid esters of chloropropanediol isolated from goat milk fat in small quantities were subjected to a stereospecific analysis via phospholipase C and phosphocholine esters as intermediates. Synthetic rac‐1‐chloro‐2,3‐dioleoyl‐propanediol was prepared by standard methods and was used as a control. The stereospecific analyses were performed following a release of the fatty acids from the primary positions of each chloropropanediol diester with pancreatic lipase. The resulting X‐1‐chloro‐2‐acylpropanediols were then converted into the corresponding phosphocholine derivatives by a stepwise reaction with phosphorus oxychloride and choline chloride. The X‐1‐chloro‐2‐acyl‐3‐phosphocholinepropanediols were subjected to hydrolysis with phospholipase C (C. perfringens), which hydrolyzed 50% of the phosphatide within two min and the rest of it in two hr. From previous experience with glycerol esters, it was assumed that the more rapidly hydrolyzed molecules were the sn‐1‐chloro‐2‐acyl‐propanediol derivatives and the more slowly hydrolyzed ones the sn‐2‐acyl‐3‐chloropropanediol derivatives. A hydrolysis with phospholipase A2 (Crotalus adamanteus) released 50% of the total fatty acid along with the corresponding lyso compound within 10 min, after which there was no further reaction. The hydrolysis products were assayed directly by gas liquid chromatography (GLC) or were isolated by thin layer chromatography (TLC) prior to quantitation by GLC. Both naturally occurring and synthetic chloropropanediol diesters behaved similarly on stereospecific analysis and were therefore concluded to be racemic.
Influence of dietary fiber on lipids and aortic composition of vervet monkeys
Authors: Kritchevsky David , Davison Larry M. , Goodman Gordon T. , Tepper Shirley A. , Mendelsohn Dennis
Published: December 2006

A semipurified, cholesterol‐free diet containing 40% carbohydrate can produce aortic sudanophilia or aortic atherosclerosis in vervet monkeys (Ceroopithecus aethiops pygerethrus) depending on the particular carbohydrate fed. Four groups of vervet monkeys (three males and three females per group) were fed semipurified diets containing lactose. Two of the groups were also fed 15% cellulose (C) or 15% cellulose plus 0.1% cholesterol (CC); the two other groups were fed 15% pectin (P) or 15% pectin plus 0.1% cholesterol (PC). The average serum total cholesterol and low density lipoprotein cholesterol levels over the entire feeding period (mg/dl±SEM) were, for C, 156±14 and 95±5; for P, 173±15 and 112±8; for CC, 187±27 and 122±21; and for PC, 155±11 and 108±7. Cholesterol levels at autopsy (mg/dl±SEM) were, for C, 103±6; for P, 108±16; for CC, 92±9; and for PC, 106±7. Aortic sudanophilia (percentage of area) was, for C, 5.9±2.7; for P, 13.5±9.4; for CC, 5.3±2.1; and for PC, 21.6±10.3. Dietary pectin led to more severe sudanophilia (increased by 129% in the absence of cholesterol and by 308% in its presence) than did cellulose. Analysis of aortic glycosaminoglycans (GAG) revealed that dermatan sulfate levels fell in both cholesterol‐fed groups, and chondroitin sulfate fell in aortas of group CC. Heparan sulfate levels were unaffected by cholesterol feeding. Hexuronic acid, galactosamine and hexosamine levels were elevated in the pectin‐fed monkeys, but levels were unaffected by dietary cholesterol. Pectin may contribute galactosamine and glucuronic acid towards aortic GAG.
Lipid content of swine influenza and other vaccines
Authors: Leskawa Kenneth C. , Hogan Edward L. , Dasgupta Somsankar , Chien Jaw‐Long , Erwin Robert E. , Brostoff Steven W.
Published: December 2006

An analysis of the lipids in swine influenza vaccines was performed, comparing six different lots of swine influenza, other influenza and noninfluenza vaccines. Cholesterol content and phospholipid content varied greatly, but there were no major differences between the types of vaccines. Appreciable amounts of phosphatidylethanolamine were found in only one swine influenza vaccine. The major phospholipids of influenza vaccines were phosphatidylcholine, sphingomyelin and phosphatidic acid. A detectable amount of phosphatidylserine was not found in any swine influenza vaccine, but was present in two of three nonswine influenza vaccines. Only two of six swine influenza vaccines showed trace amounts (less than 0.5 μg/ml) of ganglioside (GM3). However, larger quantities of galactocerebroside were found (2.24–6.43 μg/ml) in all influenza vaccines examined, including swine influenza vaccines.
Quantitation of dolichyl phosphate and dolichol in major organs of the rat as a function of age
Authors: Kennedy Keller R. , Nellis Steven W.
Published: December 2006

Previous studies in mice and humans have shown age‐related increases in the levels of dolichol in all organs investigated. In the present study, the levels of dolichyl phosphate, the physiologically active form of dolichol, as well as dolichol and cholesterol were determined in five major organs of the rat from 4 to 14 wk of age. As observed for mice and humans, the levels of dolichol increased in all tissues examined, especially testis where an eightfold increase was found. Cholesterol levels remained relatively constant in all tissues examined except brain, where a threefold increase was observed. Hepatic dolichyl phosphate levels decreased slightly during growth while nonhepatic tissues showed moderate (1.2–1.7‐fold) increases. It is proposed that steady‐state levels of hepatic dolichyl phosphate are maintained in the face of constant de novo synthesis by a combination of two pathways: export, either via the circulation or the previously demonstrated fecal route (Connelly and Keller [1984]bioscience Reports 4, 771–776) and conversion to dolichol with subsequent accumulation.
Dietary lipid modulation of immune responsiveness
Authors: Erickson Kent L. , Adams Dorothy A. , McNeill Carla J.
Published: December 2006

The influence of dietary fat concentration and saturation on blastogenesis, cytotoxicity, antibody response and fatty acid composition of murine splenic lymphocytes was studied. Blastogenesis of lymphocytes from dietarily manipulated mice in response to alloantigens from control mice was significantly greater for those mice fed a diet containing minimal essential fatty acids (EFA) as the only fat source (EFA control) than those fed an EFA‐deficient diet. When the dietary fat concentration was increased, blastogenic responses decreased compared to the EFA control diet. Lymphocyte‐mediated cytotoxicity against allogeneic melanoma cells was greater for mice receiving diets with EFA only than for those deficient in EFA. However, cytotoxicity responses of mice fed additional polyunsaturated fat (PUF) decreased as concentration increased, whereas responses of mice fed the saturated fat (SF) diets decreased only when the dietary fat concentration was greater than 8%. As compared to diets with EFA control, direct plaqueforming cell (PFC) response was decreased for mice fed high levels of PUF and increased for mice fed high levels of SF; however, no difference in the percentage of IgM‐positive cells was observed. These changes in PFC response were inversely related to the levels of linoleic acid in the lymphocyte. Thus, high levels of dietary fat, and particularly PUF, suppress lymphocyte functions when EFA requirements are met, whereas low levels (EFA control) intensify these responses. EFA deficiency, however, suppresses some lymphocyte responses. Thus, dietary lipids differentially modulate the levels of T‐ and B‐cell responsiveness.
Intralipid alters macrophage membrane fatty acid composition and inhibits complement (C2) synthesis
Authors: Strunk R. C. , Kunke K. S. , Kolski G. B. , Revsin B. K.
Published: December 2006

Intralipid (IL) is a soybean oil emulsion commonly used as a parenteral nutrient. IL is taken up by macrophages. These cells are a site of synthesis of several of the proteins in the complement system, a major mediator of the humoral system. These studies were undertaken to determine whether IL has an effect on the production of the second (C2) and the fourth (C4) components of complement by guinea pig and human macrophages in vitro. Guinea pig macrophages incubated with IL, in concentrations from 5 to 40 mg/dl, produced significantly decreased amounts of C2 and C4 when compared with controls (decreases from 40% at 5 mg/dl to 60% at 40 mg/dl). Human macrophages incubated in IL, 19 or 38 mg/dl, also produced significantly decreased amounts of C2 when compared to controls (decreases were 45 and 50% at 19 and 38 mg/dl, respectively). The maximum concentration of IL used in these studies did not significantly affect cell viability, or the production of lysozyme or β‐glucosaminidase. For human macrophages, which were studied more thoroughly, the inhibition of C2 production was reversible. C2 levels returned to normal after removal of IL. Cells stimulated with opsonized zymosan produced levels of C2 comparable to stimulated control cells, despite the continued presence of IL within the cells. Human macrophages incubated with arachidonic acid, in addition to IL, produced C2 as well as control cells did. Thus, IL appears to have a selective, reversible effect on C2 production. It is possible that a general increase in fat metabolism, in response to the ingestion of IL, nonspecifically consumed arachidonic acid, decreasing its availability as a substrate for a cell product important in production of C2. Since the effects on C2 production were seen with concentrations of IL commonly seen in plasma of infants receiving IL intravenously, these studies have implications for the clinical use of oil emulsions in parenteral nutrition.
Stearoyl‐CoA desaturase activity in adipose tissue and liver of the cardiomyopathic hamster
Authors: Barakat Hisham A. , Brown William E. , Debnath Sadhana
Published: December 2006

Stearoyl‐CoA desaturase activity and the fatty acid composition of lipids of adipose tissue and liver were determined in 35‐ and 180‐day‐old cardiomyopathic hamsters and age‐matched normal controls. Enzyme activity was unchanged in the adipose tissue of 35‐day‐old animals but was significantly depressed in the 180‐day‐old cardiomyopathic hamsters. In the liver, stearoyl‐CoA desaturase activity was significantly lower in the 35‐day‐old disease animals but was unchanged in the 180‐day‐old animals. The analysis of the fatty acid composition of the lipids isolated from adipose tissue showed an increase in the relative percentage of saturated fatty acids accompanied by a decrease in the relative percentage of unsaturated fatty acids in both age groups of the cardiomyopathic hamsters. However, linoleic acid content was increased in the diseased animals. Similar changes in fatty acid composition of lipids from the livers of 35‐day‐old cardiomyopathic hamsters were observed, but no significant differences in the fatty acid composition between 180‐day‐old cardiomyopathic hamsters and normal controls were observed. The changes in the fatty acid composition appear to be related to the observed changes in desaturase activity. In is concluded that such changes in desaturase activity and fatty acid composition could affect the normal structure and functions of membranes and membrane‐related processes.
Gas chromatographic separations of di‐ and monoacylglycerols based on the degree of unsaturation and positional placement of acyl groups
Authors: Itabashi Yutaka , Takagi Toru
Published: December 2006

Gas liquid chromatographic analysis of diacylglycerols (DGs) and monoacylglycrols (MGs) prepared by Grignard degradation of the triacylglycerols of plant and fish oils was examined as acetate and trimethylsilyl (TMS) ether derivatives on several polar cyanosiloxanes. Satisfactory separations of mixtures of DGs or MGs from simple plant oils based on carbon number and degree of unsaturation, as either acetates or TMS ethers, were obtained on SILAR 10C. In addition, the TMS ethers were effectively separated on the basis of the positional distribution of fatty acid in the acylglycerol molecule, but the acetates of the positional isomers overlapped. The equivalent chain lengths (ECLs) of DGs with 28–42 total acyl carbons and 0–6 double bonds, and MGs with 14–22 acyl carbons and 0–6 double bonds, are presented for both derivatives. The influence of column temperature on the ECLs is discussed.
Effect of dietary taurine on bile acid metabolism in guinea pigs
Authors: Kibe Akihiro , Wake Chieko , Kuramoto Taiju , Hoshita Takahiko
Published: December 2006

The effect of oral administration of taurine (200–300 mg daily) on the metabolism of bile acids was studied in male guinea pigs which have predominantly glycine conjugated bile acids. The results were summarized as follows: (a) oral administration of taurine for 10 days increased taurine‐conjugated bile acids and the ratio of glycine‐to taurine‐conjugated bile acids (G:T ratio) shifted from 3.95 to 0.19; (b) in taurine fed guinea pigs, the half‐life of chenodeoxycholic acid (CDC) was about 40% shorter than that in controls and the fractional turnover rate increased by 70%; (c) the synthetic rate (mg/day/500 g body weight) of bile acids increased from 4.28 to 7.27 by taurine feeding; (d) hepatic cholesterol 7α‐hydroxylase activity was increased 2.4‐fold by taurine feeding; (e) the total pool size of bile acids did not change significantly but the amount of lithocholic acid in the caecum and large intestine increased by about 40%; (f) neither free cholesterol nor cholesterol ester levels in liver and serum changed significantly. Results of this study suggest that changing the G:T ratio in the bile acid conjugation pattern may influence the rate of hepatic bile acid synthesis.
Effects of diet and high density lipoprotein subfractions on the removal of cellular cholesterol
Authors: Jackson Richard L. , Glueck Charles J. , Mathur Satya N. , Spector Arthur A.
Published: December 2006

The effects of isocaloric substitutions of dietary polyunsaturated and saturated fat on the composition and function of plasma high density lipoproteins (HDLs) were studied in 3 normal subjects who were fed saturate‐rich and polyunsaturate‐rich diet programs. Compared to the saturated diets (P/S=0.4), polyunsaturated fat diets (P/S=4 or 2) reduced both plasma cholesterol and triglyceride levels. In 2 of the subjects, HDL cholesterol concentrations increased with polyunsaturated fat caused a reduction in HDL fatty acyl content of oleate and an increase in linoleate. To determine whether the altered composition affected the removal of cell membrane cholesterol, HDL and their subfractions, HDL2 and HDL3, which were isolated from each of the diets, were incubated with Ehrlich ascites cells in vitro. The cells were prelabeled with [3H] cholesterol, and the release of labeled cholesterol from the cells into the medium containing the various HDL fractions was determined. HDL, irrespective of the type of dietary fat, caused a release of [3H] cholesterol from the cells into the medium. The amount of [3H] cholesterol recovered in the medium was dependent on the absolute concentration of HDL cholesterol added to the cells and was independent of the type of diet. These results indicate that HDL facilitates the removal of cholesterol from cells, but that the amount and rate of removal are independent of the changes in HDL composition that can be obtained by dietary perturbations.
Erucic acid‐induced alteration of cardiac triglyceride hydrolysis
Authors: Stam Hans , Geelhoed‐Mieras Tiny , Hülsmann Willem C.
Published: December 2006

Male Wistar rats were fed for 3 or 10 days with high erucic acid rapeseed oil (HEAR) or trierucate (TE). These diets produced increased myocardial triglyceride (TG) levels. Cardiac lipid accumulation was related to basal‐and hormone‐ (glucagon, norepinephrine) stimulated lipolysis, determined as glycerol release, which proved to be enhanced in isolated, perfused hearts from HEAR‐ and TE‐fed rats. Endogenous TG levels in isolated hearts from rats fed the stock and the sunflowerseed oil (SSO) diet were low and probably rate‐limiting for tissue lipolytic activities. HEAR feeding of rats did not modify the rate of erucic acid (22∶1) oxidation in heart. Prolonged HEAR and TE feeding led to a decrease in the endogenous TG level, a process in which the increased rate of TG hydrolysis might play an important role. The enhanced breakdown of tissue TG in hearts from TE‐and HEAR‐fed rats was accompanied by an increased release of fatty acids into the coronary effluent. Erucic acid was a major constituent of the perfusate fatty acids. Evidence is presented that the site of the intracellular TG breakdown is associated with lysosomes, since a subcellular fraction enriched in acid lipase, N‐acetyl‐β‐glucosaminidase and TG could be isolated from heart homogenates of TE‐fed rats. Fatty acids seemed to be an important regulator of tissue lipase activity: palmitate inhibited glucagon‐stimulated lipolysis, which suggests the tissue lipase is subject to product inhibition by fatty acids.
Lipids of myelin, white matter and gray matter in a case of generalized deficiency of cytochrome b5 reductase in congenital methemoglobinemia with mental retardation
Authors: Hirono H.
Published: December 2006

The lipid classes and fatty acid compositions of myelin, white matter and gray matter were analyzed in a case of generalized deficiency of cytochrome b5 reductase in congenital methemoglobinemia with mental retardation. When compared with normal data, the percentage of 24∶1 was considerably decreased and diminished unsaturation was observed in cerebrosides, whereas the sum of 24∶0 and 24∶1 was the same as in normals. The ratio of hydroxy fatty acids to total fatty acids in cerebrosides was low. The contents of cholesterol and phospholipids in white matter were reduced to 80% of the normal, whereas cerebroside was reduced to 48% of the normal.
Phospholipid composition of liver in rats fed high levels of 13‐cis retinoic acid
Authors: Alam Bassima S. , Alam Syed Q.
Published: December 2006

The composition of liver phospholipids was studied in rats fed for 4 weeks diets containing 0, 100 or 300 mg 13‐cis retinoic acid per kg diet. There was a significant decrease in phosphatidylcholine content, whereas the levels of phosphatidylethanolamine were slightly increased in liver phospholipids of rats fed 13‐cis retinoic acid. The fatty acid composition of total phospholipids, PC, PE, and PI+PS fractions revealed a general increase in the levels of 18∶2 and 20∶3ω6, whereas the levels of 20∶4ω6 and C22 fatty acids were reduced in most of the hepatic phospholipids isolated from rats fed 13‐cis retinoic acid containing diets. A decrease in the double‐bond index of fatty acids was also observed in phospholipids of rats fed 13‐cis retinoic acid. The data suggest that high levels of 13‐cis retinoic acid may possibly be influencing the activities of microsomal desaturating and chain‐elongating enzymes in the liver.
Effect of dietary vitamin E on sulfolipid synthesis in rat submandibular salivary gland
Authors: Pritchard E. T. , Chan A. C.
Published: December 2006

The effect of feeding diets containing various levels of vitamin E for 6 months on the in vitro synthesis of sulfolipids in rat submandibular salivary glands (SMG) was elucidated. The incorporation of [35S]sulfate into sulfolipid of SMG from rats on deficient or “normal” vitamin E diets was quite similar, however, the uptake was significantly increased in glands from rats on diets high in vitamin E. Whereas, in many instances, antioxidants can mimic the effect of vitamin E, in the present study, the antioxidant N,N′‐diphenyl‐ρ‐phenylene diamine (DPPD) was actually found significantly to depress sulfolipid‐labeling below that noted in SMG from all other diets. The results suggest that in the synthesis of SMG sulfolipid the action of vitamin E may be more than that of a simple antioxidant.