bluuebunny/crossref_metadata_2025 huggingface dataset:
Composition and variability of the branched‐chain fatty acid fraction in the milk of goats and cows
Authors: Massart‐Leën A. M. , De Pooter H. , Decloedt M. , Schamp N.
Published: December 2006

Branched‐chain fatty acids of the milk fat of goats were analyzed by high resolution gas chromatography‐mass spectrometry. Iso‐ and anteiso‐acids predominated, but a range of other monomethyl‐branched components, mostly with methyl‐substitution on carbons 4 and 6, was present. Analysis of the milk fat of cows revealed the presence of iso‐ and anteiso‐fatty acid; other mono‐methyl‐substituted fatty acids, as found in the milk fat of the goat, were virtually absent. Only a trace amount of 6‐methylhexadecanoate was detected. The difference between goats and cows in the effectiveness with which these animals metabolize propionyl‐CoA and methylmalonyl‐CoA is discussed.
Phospholipid acyl group composition in normal and tumoral nerve cells in culture
Authors: Montaudon Danièle , Louis Jean‐Claude , Robert Jacques
Published: December 2006

We have studied the fatty acid composition of total phosphoglycerides from various types of nerve cells in culture. Primary cell cultures were compared with tumoral cell strains. Glial cells exhibited no characteristic pattern when compared to neurons. Tumoral cell phosphogly cerides contained much higher levels of octadecenoic acid and lower levels of C‐20 to C‐22 polyunsaturated fatty acids than normal cell phosphoglycerides. This observation seems to be a general feature in tumoral cell membranes. It could be of interest in respect to the membrane fluidity of cancer cells.
Acyl exchange between oleoyl‐CoA and phosphatidylcholine in microsomes of developing soya bean cotyledons and its role in fatty acid desaturation
Authors: Stymne Sten , Glad Gunnar
Published: December 2006

Microsomes of developing soya bean cotyledons transfer oleate from oleoyl‐CoA to phosphatidylcholine (PC) by two different mechanisms: one in which oleate transfer is accompanied by the release of free CoA and another which results in the exchange of oleate from oleoyl‐CoA for unsaturated 18‐carbon fatty acids of PC. The acyl exchange can be demonstrated only when bovine serum albumin is present in the incubation medium. ATP‐dependent acyl‐CoA synthetase is not involved in the exchange process, which apparently does not require any cofactors. In light of this exchange process, the oleate desaturase system was reinvestigated in order to determine what the actual substrate for this system is. Upon incubation of microsomes with high concentrations of [14C] oleoyl‐CoA, bovine serum albumin and NADH, it could be conclusively demonstrated that most oleic acid is desaturated while part of the PC molecule. The amounts of [14C] linoleoyl‐CoA formed could be explained entirely by the acyl exchange. The physiological significance of the acyl exchange system is discussed. A new method for separation of acyl‐CoA from other lipids and free CoA using reversed phase column chromatography also is described.
4‐demethyl‐,4‐monomethyl‐and 4,4‐dimethylsterols in some vegetable oils
Authors: Kornfeldt Anna , Croon Lars‐Börje
Published: December 2006

The content of 4‐demethyl‐, 4‐monomethyl‐ and 4,4‐dimethylsterols in 13 vegetable oils was found to vary between 0.10–1.4%, 0.01–0.08% and 0.02–0.29%, respectively. The largest amount of demethylsterols was found in maize and wheat germ oils, whereas the largest amounts of the dimethylsterols were found in olive and linseed oils. The predominating demethylsterols were sitosterol, campesterol, stigmasterol and Δ5‐avenasterol. Among the 4‐monomethylsterols, obtusifoliol, gramisterol, cycloeucalenol and citrostadienol predominated, but usually more than 10 components were found in this fraction. The composition of the 4,4‐dimethylsterol fraction was also rather complex, with the 9,19‐cyclopropanesterols together with α‐ and β‐amyrin predominating. In most of the oils, characteristically high or low percentages of some sterols were found, and a few specific sterols were also noted. A scheme useful for characterization is presented.
Iodination of docosahexaenoic acid by lactoperoxidase and thyroid gland in vitro: Formation of an lodolactone
Authors: Boeynaems J. M. , Watson J. T. , Oates J. A. , Hubbard W. C.
Published: December 2006

In the presence of iodide, hydrogen peroxide and lactoperoxidase, docosahexaenoic acid (22∶6ω3) was converted into iodinated compounds. The major product was identified as 5‐iodo‐4‐hydroxy‐7, 10,13,16,19‐docosapentaenoic acid, γ‐lactone, on the basis of125I incorporation, mass spectrometry, chemical modifications and proton nuclear magnetic resonance spectroscopy. Iodolactonization of docosahexaenoic acid occurred in the rat thyroid in vitro and was inhibited by the peroxidase inhibitor methimazole. These data indicate that formation of an idolactone constitutes one pathway of docosahexaenoic acid metabolism which could be expressed in tissues containing an iodide peroxidase.
Free radical polymerization and lipid binding of lysozyme reacted with peroxidizing linoleic acid
Authors: Funes Jorge , Karel Marcus
Published: December 2006

Insolubilization and polymerization of proteins exposed to peroxidizing lipids may be due either to cross‐linking with incorporation of fragments of the lipid oxidation products, or to free radical transfer from lipid to protein and subsequent free radical polymerization of protein. The second mechanism which has been proposed was inferred from measurements of electron spin resonance signals in proteins. In this study, uniformly labeled linoleic acid, [14C(U)] LA, was reacted with lysozyme. Volatile oxidation products of LA were also used in some experiments. Incubation was done in the absence of water. Oligomers of lysozyme, as well as the monomer, were isolated after incubation, and the [14C] label incorporated into each fraction was determined. The results show that the dominant mechanism of protein polymerization after exposure to peroxidizing linoleic acid is the transfer of free radical from lipid to protein, and subsequent free radical polymerization.
Eicosa‐5,11,14‐trienoic and octadec‐5‐enoic acids of the reproductive tract of the male house cricket (Acheta domesticus) and field cricket (Gryllus spp.)
Authors: Worthington R. E. , Brady U. Eugene , Hitchcock H. L.
Published: December 2006

The reproductive tracts (testes, seminal vesicles, accessory glands, ejaculatory duct) of male house crickets (Acheta domesticus) and field crickets (Gryllus spp.) contain ca. 6% of eicosa‐5,11,14‐trienoate in total tissue fatty acids. This fatty acid is concentrated primarily in the phosphatidylcholine fraction of phospholipids (12.6%) and occurs in no more than trace amounts (<0.1%) in neutral lipids. The 18∶1 fatty acid fraction of total tissue lipid fatty acids consisted of 2 isomers with unsaturation in the Δ5 and Δ9 positions in proportions of ca. 33 and 67 mol %, respectively.
Lack of specificity in accumulation of sterols byPhytophthora cactorum
Authors: Gonzales Robert A. , Parks Leo W.
Published: December 2006

The kinetics of sterol uptake inPhytophthora cactorum were examined. A Vmax of 4.81×10−5 μmol/min/mg dry wt and an average apparent Km of 18.0 μM were determined for both cholesterol and sitosterol accumulation. Selectivity for specific sterols was not apparent in the accumulation, esterification, or distribution of sterols byPhytophthora cactorum.
Lack of catabolism of brain cholesterol
Authors: Dhopeshwarkar Govind A. , Subramanian Carole
Published: December 2006

Since direct intracranial injections of precursors indicate that cholesterol is synthesized in the brain at all ages, there must be a mode of disposal also. The sterol nucleus itself is not degraded by mammalian systems but the side chain can be metabolized. [26‐14C] Cholesterol was therefore injected directly into the brain of 80 to 19‐day‐old rats which were sacrificed at the end of 24 hr, 1 week and 2 weeks after injection. The results indicate that, irrespective of the interval between injection and sacrifice, all of the radioactivity was found in the free cholesterol or the cholesterol component of the sterol esters. No radioactivity was found in the fatty acids of the phospholipids. We therefore conclude that the side chain of the cholesterol does not get metabolized to propionyl CoA, which in turn, could lead to fatty acid synthesis. Radioactivity in the serum, even after 2 weeks, indicates that there must be a slow but steady exchange between the brain and the blood that would explain the route of exit for brain cholesterol.
Identification of arachidonic acid in gulf of Mexico shrimp and degree of biosynthesis inPenaeus setiferus
Authors: Lilly Martha L. , Bottino Nestor R.
Published: December 2006

An icosatetraenoic fatty acid, though to be allcis‐5,8,11,14‐icosatetraenoic acid (arachidonic acid), was isolated from shrimp total lipid. The acid was subjected to partial reduction with hydrazine hydrate, with subsequent isolation of the monoenoic reaction products which were shown to becis in structure. These were then cleaved by periodate‐permanganate oxidation and the resulting mono‐and dicarboxylic acid were converted to methyl esters. Identification of the resulting mono‐ and dicarboxylic acids indicated that the original icosatetraenoic acid had the allcis‐5,8,11,14 pattern of double bonds, and it was thus identified as arachidonic acid. Experiments were also performed to study the synthesis of arachidonic acid 20∶4(5,8,11,14) from linoleic acid, 18∶2(9,12) in microsomes prepared from shrimp hepatopancreas and tail muscle tissue. Each step of the pathway 18∶2(9,12)→18∶3(6,9,12)→20∶3(8,11,14)→20∶4(5,8,11, 14) was assayed separately, and the level of activity of each enzyme was expressed as percentage conversion of substrate to product. It was found that, in each step of the sequence, the enzyme activity in the shrimp tissue was very low compared to the activity found in rats. These and previous observations seem to indicate that the arachidonic acid in shrimp tissue originates mostly in the diet.
In vitro conversion of saturated to monounsaturated fatty acid by Ehrlich ascites cells
Authors: Mercuri Osvaldo , Tomás María Elena De , de Antueno Roberto J.
Published: December 2006

In this paper, evidence is presented on the capacity of Ehrlich ascites cells to synthesize in vitro monounsaturated fatty acids from radioactive palmitate. Localization of the double bond was determined by ozonolysis and subsequent reduction of the ozonides to aldesters followed by gas liquid chromatography. These results proved that Ehrlich ascites cells have a Δ9 desaturase that catalyzes the biosynthesis of palmitoleic acid from palmitic acid and oleic and vaccenic acid via elongation‐desaturation and desaturation‐elongation, respectively, using palmitic acid as substrate. Furthermore, it is shown that, as in the hepatic cells, Δ9 desaturase enzyme activity of the tumoral cells is associated with the endoplasmic reticulum. The electron transport components involved in the desaturase system, i.e., NADH‐cytochrome bs reductase and NADH‐cytochrome c reductase, were also measured. The activities of these enzymes do not appear to be rate‐limiting in the desaturase activity of these tumoral cells.
The influence oftrans‐acids on desaturation and elongation of fatty acids in developing brain
Authors: Cook Harold W.
Published: December 2006

trans‐Monounsaturated acids account for up to 3% of the total octadecenoic acyl chains of human brain lipids. To investigate the influence oftrans‐acids on desaturation and chain elongation of fatty acids, in vitro and in vivo experiments with rat brain were performed. In the in vitro assays of Δ9 desaturation, Δ6 desaturation and chain elongation,trans,trans‐dienoic acid was inhibitory, particularly to chain elongation. Slight differences between the inhibitory effects oftrans‐monoenoic acids and theircis‐isomers were observed. In an in vivo model, unlabeled fatty acid (stearate, oleate, elaidate, linoleate, linoelaidate, arachidonate, ortrans‐monoene from margarine) was injected simultaneously with [1‐14C] linoleic acid into the brains of suckling rats. Linoelaidate and oleate inhibited desaturation and elongation of linoleate, whereas elaidate, stearate andtrans‐monoene from margarine were stimulatory. While the demonstration of differences betweencis andtrans monoenic isomers required relatively high levels of the test acids, it appears thattrans‐acids can influence desaturation and elongation enzymes that lead to acyl chain modification in the central nervous system.
Enzymatic formation of cholesteryl ester from cholesterol by gallbladder mucosa
Authors: Neiderhiser Dewey H.
Published: December 2006

The formation of cholesteryl ester from cholesterol and acyl CoA catalyzed by the enzyme acyl CoA: cholesterol acyltransferase (EC 2.3.1.26) was studied in guinea pig gallbladder mucosa homogenate and the subcellular fractions. The enzymatic activity was enriched in the microsomal fraction. Highest activity was observed with palmitoyl, stearoyl or oleoyl CoA as substrate. Lowest activity was observed with linoleoyl CoA. These data elucidate one mechanism for the formation of cholesteryl ester from cholesterol by the gallbladder wall.
Effect of buffer constituents on rat liver 3‐hydroxy‐3‐methyl glutaryl coenzyme A reductase
Authors: Srikantaiah M. V. , Noble N. , Orenstein L. , Morin R. J.
Published: December 2006

Rat liver microsomes prepared in Tris buffer exhibited 3 to 10 times higher 3‐hydroxy‐3‐methyl glutaryl CoA reductase specific activity than microsomes prepared with potassium phosphate buffer. This higher activity was observed in rats killed during mid‐light cycle, but microsomes from rats killed during mid‐dark cycle showed no significant difference in enzyme activity between buffers. When microsomes prepared in the 2 different buffers were preincubated with ATP and MG++, enzyme activity was inhibited to the same extent. The cytosol fraction in each of the 2 different buffer preparations possessed similar phosphatase activity. The higher 3‐hydroxy‐3‐methyl reductase activity in Tris buffer, therefore, does not appear to be due to differences in phosphorylation or dephosphorylation activity.
Lipoproteins of fetal and newborn calves and adult steer: A study of developmental changes
Authors: Forte Trudy M. , Bell‐Quint Julia J. , Cheng Fenny
Published: December 2006

Serum lipoproteins in fetal and newborn calves were characterized and compared with those of adult animals. Fetal calf serum contains only low density (LDL) and high density (HDL) lipoproteins; the LDL is the major lipoprotein class. Fetal LDL are ca. 26.0 nm diameter and are morphologically unusual in that particles form linear aggregates or “chains” in which LDL have flattened, parallel sides. These particles contain only apolipoprotein B and are high in polar lipids. Fetal HDL consist of 8.2‐nm, round particles which contain large amounts of chlesteryl ester thus suggesting an active lecithin: cholesterol acyltransferase system in the fetal state. The major protein in fetal HDL is apolipoprotein A−I (80%); however, another component with a molecular weight (MW) of ca. 9,000 is also present. Newborn calves show a 5‐fold increase in HDL concentration. These particles are 9.0 nm spherical particles and they contain mainly apolipoprotein A−I although C‐apolipoproteins are also present; the lipid and apolipoprotein composition of newborn HDL is similar to that of adults. Newborn calves possess very low density (VLDL) lipoproteins which have a mean diameter of 61 nm and are similar in size and composition to those of adult animals; their apolipoprotein composition is principally apolipoprotein B, although C‐apolipoproteins and apolipoprotein A−I are also present. The LDL of neonatal and adult animals are similar in morphology, chemical composition and apolipoprotein content. In both instances, LDL are round particles ca. 19.0 nm diameter which contain less polar lipids than the fetal animal. Apolipoprotein B is the major protein in newborn LDL, but adult LDL additionally contains a protein of 27,000 MW which probably represents apolipoprotein A−I from overlapping α‐migrating particles in this region. The altered morphology and composition of fetal LDL, together with the lack of VLDL, suggest that the LDL particles may be synthesized de novo.
Lactoperoxidase‐catalyzed lodination of arachidonic acid: Formation of macrolides
Authors: Boeynaems J. M. , Reagan D. , Hubbard W. C.
Published: December 2006

In the presence of iodide and hydrogen peroxide, lactoperoxidase catalyzed the conversion of arachidonic acid into several iodinated products; the major one was previously identified as an iodo‐δ‐lactone. Two minor and less polar products have now been characterized as 15‐iodo‐14‐hydroxyeicosatrienoic acid, ω‐lactone and 14‐iodo‐15‐hydroxyeicosatrienoic acid, ω‐lactone, on the basis of125I incorporation, mass spectrometry, proton magnetic resonance spectroscopy and chemical modifications.
Photosensitized oxidation of methyl linoleate: Secondary and volatile thermal decomposition products
Authors: Frankel E. N. , Neff W. E. , Selke E. , Weisleder D.
Published: December 2006

Studies of photosensitized oxidation of methyl linoleate show that the greater relative concentration of 9‐ and 13‐hydroperoxides than 10‐ and 12‐hydroperoxides is characteristic of singlet oxygenation and not due to either simultaneous autoxidation or type 1 photosensitized oxidation. Cyclization of the internal 10‐ and 12‐hydroperoxides accounts for their lower relative concentrations. Secondary products separated by silicic acid and high pressure liquid chromatography were characterized spectrally (IR, UV,1H‐NMR,13C‐NMR, GC‐MS). Major secondary products included diastereomeric pairs of 13‐hydroperoxy‐10,12‐epidioxy‐trans‐8‐octadecenote (I and III) and 9‐hydroperoxy‐10,12‐epidioxy‐trans‐13‐octadecenoate (II and IV); minor secondary products included hydroperoxy oxy genated and epoxy esters. Thermal decomposition of the hydroperoxy cyclic peroxides produced hexanal and methyl 10‐oxo‐8‐decenoate as major volatiles from I and III and methyl 9‐oxo‐nonanoate and 2‐heptenal from II and IV. Hydroperoxy cyclic peroxides may be important sources of volatile decomposition products of photooxidized fats.
The effect of environmental temperature on sebum composition in tropical and temperate breeds of cattle
Authors: O'Kelly J. C. , Reich H. P.
Published: December 2006

This study compared the effect of environmental temperature on sebum composition in 2 breeds of cattle, British (SH) and Brahman (GB), which differ in their abilities to tolerate heat. By long‐term exposure of both breeds to environmental temperatures of 24 C and 32 C and the more heat‐tolerant GB breed to 38 C, it was possible to make breed comparison at (a) different body temperatures, i.e, when all animals were exposed to the same environmental temperature, and (b), at the same body temperature, i.e., when the 2 breeds were exposed to different ambient temperatures. The composition of sebum excreted to saturation level on the skin surface was determined. At the same body temperatures, the amounts of fatty acids in each lipid class were higher in GB than in SH animals except during hyperthermia when the amounts of triglyceride fatty acids were similar in both breeds. The total amounts of individual fatty acids except 14∶1, 16∶1, 20∶0 and 14∶OH were higher in both breeds at 32 C than at 24 C. The GB cattle excreted more essential fatty acids (EFA) than the SH cattle at 24 C and at 32 C. There was a significant genotype by environment interaction in the amounts of EFA partitioned between triglycerides and wax esters; in GB cattle, the amount of EFA excreted in triglycerides decreased whereas the amount excreted in wax esters increased with rising body temperature.
Volatile hydrocarbons from photosynthetic membranes containing different fatty acids
Authors: Sandmann Gerhard , Böger Peter
Published: December 2006

A cell‐free plant system was developed generating short‐chain volatile hydrocarbons as markers of light‐induced copper‐mediated peroxidation of fatty acids present either as endogenous constituents of photosynthetic membranes or added exogenously. Different polyunsaturated fatty acids are present in the blue green algaeAnacystis nidulans, Anabaena variabilis andSpirulina platensis. The first species has no polyunsaturated acids. Thylakoids isolated from these algae produce different short‐chain volatile hydrocarbons. The location of the double bond of dienoic or higher polyunsaturated fatty acids most distant from the carboxyl group determines the chain length of hydrocarbons evolved. Their number of C‐atoms is the same as found beyond this double bond of the fatty‐acid molecule (ω‐1). This pattern of volatile hydrocarbons produced is in contrast to thermolytic cleavage. Malondialdehyde is formed only when at least 3 double bonds are present in the fatty acid. Peroxidation of endogenous thylakoidal and added fatty acids is completed within 24 hr; a maximum of 1% of the carbon skeleton can be recovered as volatile hydrocarbons.
Lung phosphatidylcholine and fasting in male and female rats
Authors: Abe Masao , Endo Makoto , Nagai Hiroshi
Published: December 2006

Lung from male and female rats fasted for 4 days were used. Phospholipid, phosphatidylcholine and its molecular species were analyzed in lungs from these rats and effects of fasting upon the biosynthesis of phosphatidylcholine in lungs from both sexes were determined using radioactive choline. The molecular species of phosphatidylcholine in both male and female rats did not differ with fasting except the monoenoic species. Incorporation of choline into phosphatidylcholine in both male and female rats significantly increased after fasting, but distribution of radioactivity in phosphatidylcholine yielded similar values in each group. These results suggest that the decrease of saturated phosphatidylcholine content after fasting may be not due to specific change in saturated phosphatidylcholine.
Reactivity of key metabolic sterols in standard colorimetric assays for cholesterol
Authors: Sarkar Chitta P. , Cenedella Richard J.
Published: December 2006

The reaction of lanosterol, desmosterol and 7‐dehydrocholesterol, key intermediates in cholesterol biosynthesis, were‐compared with cholesterol in 3 standard colorimetric assays for cholesterol based on formation of chomogens with acetic anhydride, ferric chloride and ferrous sulfate. Marked differences in the reaction of the sterols in the different assays were due both to formation of chomogens with qualitatively similar spectral patterns but with greatly different extinctions and to formation of chromogens with clearly different absorption maxima. For example, in all assays, cholesterol and desmosterol formed chromogens with very similar absorption spectra but with varying extinctions, whereas the lanosterol chromogen in all assays was different from cholesterol's in both absorption maxima and in extinctions. The findings show that attempts to measure tissue sterol levels by colorimetric methods can result in great errors when cholesterol is not the sole sterol. Also, the unique spectral properties of the lanosterol chromogen formed in the Liebermann‐Burchard reaction (a sharp absorption peak at 450 nm) suggests the possible use of this method as a qualitative test for lanosterol.
High performance liquid chromatography and glass capillary gas chromatography of geometric and positional isomers of long chain monounsaturated fatty acids
Authors: Svensson Lennart , Sisfontes Leslie , Nyborg Göran , Blomstrand Rolf
Published: December 2006

Positional and geometrical isomers of monounsaturated long chain fatty acids were analyzed by the combination of high performance liquid chromatography (HPLC) and glass capillary gas chromatography (GC). A preparative group separation ofcis andtrans isomers of the monounsaturated fatty acid methyl esters was achieved according to chain length by reversed‐phase HPLC, and using a highly sensitive interference refractive index detector. After collection of the different fractions containingcis andtrans forms of the monounsaturated fatty acid methyl esters, the fractions were analyzed for their content of positional isomers using glass capillary GC with Silar‐5 CP as stationary phase. The preparative step in the HPLC was also used analytically for the determination of the ratio between thecis andtrans monounsaturated fatty acids. A comparison was made between the results obtained with the HPLC technique and the results of a GLC technique with a packed OV‐275 column. There was a good correlation between the 2 techniques with a tendency to highertrans values with the HPLC technique (4%). It was shown with reference substances that 18∶1ω6‐cis to ω11‐cis and 18∶1ω5‐trans to ω12‐trans, the most common monounsaturated fatty acid isomers in partially hydrogenated vegetable oils, could be almost quantitatively recovered in the HPLC step. Most of the individual positional isomers of monounsaturated fatty acids of varying chain length could be separated and determined in the glass capillary GC step with the exception of those isomers containing the double bond in a relatively high ω‐position. The relative standard deviation of the technique as determined with reference substances was better than 4%. The described technique was applied to the analysis of the isomeric monounsaturated fatty acid content in partially hydrogenated vegetable and marine oils, and about 5 samples a day could be executed.
Chemical synthesis and spectroscopic characteristics of C18 1,2‐disubstituted cyclopentyl fatty acid methyl esters
Authors: Rojo Jose A. , Perkins Edward G.
Published: December 2006

The chemical synthesis of methyl 9‐(2′‐n‐butylcyclopentyl)nonanoate and methyl 10‐(2′‐n‐propylcyclopentyl)‐decanoate was performed using a Wittig reaction between 2‐alkylcyclopentanones and the corresponding ω‐carbomethoxyalkyl triphenylphosphonium bromides. The intermediate alkylcyclopentylidene alkanoate esters were isolated from the reaction mixture, characterized by spectrometric methods, and then catalytically hydrogenated to the desired cyclopentyl esters. Gas chromatographymass spectrometry (GC‐MS) showed that the final products contained a mixture oftrans‐ andcis‐ring isomers with small amounts of other cyclic by‐products. The GC‐retention features, the mass fragmentation pattern, and the spectroscopic characteristics of both the final and the unsaturated intermediate products are discussed.
The effect of a fish oil diet on the fatty acid composition of individual phospholipids and eicosanoid production by rat platelets
Authors: Careaga‐Houck Mónica , Sprecher Howard
Published: December 2006

When rats were fed a diet containing chow or fish oil for six weeks, the platelet phospholipid content and percent distribution were similar. In the fish oil fed animals there was a 54, 40, 41, and 24% reduction, respectively, in the levels of 20∶4(n−6) in the choline‐, ethanolamine‐, inositol‐and serine‐containing glycerophospholipids. Dietary fish oil increased the total (n−3) polyunsaturated fatty acid content in all lipids. This effect was most pronounced in the ethanolamine glycerophospholipids which now contained 26, 11, and 4 nmols of 20∶5(n−3), 22∶5(n−3), and 22∶6(n−3) in 109 cells. Ionophore A23187 stimulation of platelets from the chow fed rats resulted in the synthesis of 7, 64, and 3.5 nmols of 12‐hydroxy‐5,8,10‐heptadecatrienoic acid, 12‐hydroxy‐5,8,10,14‐eicosatetraenoic acid and 12‐hydroxy‐5,8,10,14,17‐eicosapentaenoic acid, respectively, from 1×109 cells. The values from animals fed fish oil were 4, 18, and 27 nmol/109 platelets. It was not possible to detect any lipoxygenase products from 22∶5(n−3) or 22∶6(n−3), even though both acids are readily metabolized by lipoxygenase when added directly to platelets. These findings suggest that 22‐carbon (n−3) fatty acids are not liberated when phospholipases are activated by calcium mobilization.
Cholelithiasis in hamsters: Effects of cholic acid and calcium on gallstone formation
Authors: Cohen Bertram I. , Matoba Naoyuki , Mosbach Erwin H. , Stenger Richard J. , McSherry Charles K.
Published: December 2006

Dietary cholic acid (0.1%) and/or calcium (2.6% as calcium carbonate) were added to a semipurified diet containing cholesterol and ethynyl estradiol to determine whether the incidence of pigment and/or cholesterol gallstones would be changed. Male golden Syrian hamsters were fed the experimental diets for 96 days (Group 1, control; Group 3, cholic acid plus calcium) or only an average of 60 days (Group 2, 0.1% cholic acid). Animals in Group 2 became ill (weight loss, low food intake, diarrhea) possibly due to cholic acid (or deoxycholic acid) toxicity. Cholesterol gallstones and crystals were absent in all experimental groups. The incidence of pigment gallstones was: control, Group 1, 12/16; 0.1% cholic acid, Group 2, 3/13; and 0.1% cholic acid plus calcium, Group 3, 11/22. Cholic acid with or without calcium produced an elevation of both liver and plasma cholesterol: Group 2, 80.1 mg/g and 501 mg/dl; Group 3, 103.7 mg/g and 475 mg/dl vs Group 1, 65 mg/g and 209 mg/dl, respectively. The lithogenic indices of the bile were lower in Groups 2 and 3 compared to Group 1, controls, 0.45 and 0.58 vs 1.16, respectively. The extent of the portal tract pathology could not be correlated with the presence or absence of pigment gallstones or with the levels of lithocholic acid in the hamster bile. In summary, when semipurified diets were supplemented with ethynyl estradiol and cholic acid, with and without calcium supplementation, no cholesterol gallstones formed and the incidence of pigment gallstones was not altered.
Influence of dietary fat composition on intestinal absorption in the rat
Authors: Thomson A. B. R. , Keelan M. , Garg M. L. , Clandinin M. T.
Published: December 2006

Omega‐3 fatty acids influence the function of the intestinal brush border membrane. For example, the omega‐3 fatty acid eicosapentaenoic acid (20∶5ω3) has an antiabsorptive effect on jejunal uptake of glucose. This study was undertaken to determine whether the effect of feeding α‐linolenic acid (18∶3ω3) or EPA plus docosahexaenoic acid (22∶6ω3) on intestinal absorption of nutrients was influenced by the major source of dietary lipid, hydrogenated beef tallow or safflower oil. Thein vitro intestinal uptake of glucose, fatty acids and cholesterol was examined in rats fed isocaloric diets for 2 weeks: beef tallow, beef tallow + linolenic acid, beef tallow + eicosapentaenoic acid/docosahexaenoic acid, safflower oil, safflower oil + linolenic acid, or safflower oil + eicosapentaenic acid/docosahexaenoic acid. Eicosapentaenoic acid/docosahexaenoic acid reduced jejunal uptake of 10 and 20 mM glucose only when fed with beef tallow, and not when fed with safflower oil. Linolenic acid had no effect on glucose uptake, regardless of whether it was fed with beef tallow or safflower oil. The jejunal uptake a long‐chain fatty acids (18∶0, 18∶2ω6, 18∶3ω3, 20∶4ω6, 20∶5ω3 and 22∶6ω3) and cholesterol was lower in salfflower oil than with beef tallow. When eicosapentaenoic acid/docosahexaenoic acid was given with beef tallow (but not with safflower oil), there was lower uptake of 18∶0, 20∶5ω3 and cholesterol. The demonstration of the inhibitory effect of linolenic acid or eicosapentaenoic acid/docosahexaenoic acid on cholesterol uptake required the feeding of a saturated fatty acid diet (beef tallow). These changes in uptake were not explained by differences in the animals’ food intake, body weight gain or intestinal weight. Feeding safflower oil was associated with an approximately 25% increase in the jejunal and ileal mucosal surface area, but this increase was prevented by combining linolenic acid or eicosapentaenoic acid/docosahexaenoic acid with safflower oil. Different inhibitory patterns were observed when mixtures of fatty acids were present together in the incubation medium, rather than in the diet: for example, when 18∶0 was in the incubation medium with 20∶4ω6, the uptake of 20∶4ω6 was reduced, whereas the uptake was unaffected by 18∶2ω6 or 20∶5ω3. Thus, (1) the inhibitory effect of eicosapentaenoic acid/docosahexaenoic acid on jejunal uptake of glucose, fatty acids and cholesterol was influenced by the major dietary lipid, saturated (beef tallow) or polyunsaturated fatty acid (safflower oil); and (2) different omega‐3 fatty acids (linolenic acid versus eicosapentaenoic acid/docosahexaenoic acid) have a variable influence on the intestinal absorption of nutrients.
Influence of omega‐3 and omega‐6 fatty acid sources on prostaglandin levels in mice
Authors: Dan Henderson C. , Black Homer S. , Wolf John E.
Published: December 2006

Studies from this laboratory, employing a hairless mouse model, have indicated that a polyunsaturated fatty acid source rich in omega‐3 (n−3) fatty acid (FA) inhibits ultraviolet (UV)‐carcinogenic expression, when compared to that of diets containing predominantly n−6 fatty acids. Omega‐3 FA is a poor substrate for cyclo‐oxygenase, the rate‐limiting step in prostaglandin (PG) synthesis—the latter, particularly PGE2, are known to influence tumor biology. Based upon this rationale, plasma and cutaneous PGE2 levels were determined from hairless mice fed diets containing either 4% or 12% corn or menhaden oil. After two weeks on the respective diets, plasma PGE2 levels of corn oil‐fed animals were approximately 6‐fold greater than those of the menhaden oil‐fed groups. A similar response was found in the dermis. Although the relationship to carcinogenic expression is unknown, dietary n−3 FA content can have a pronounced effect upon PGE2 levels and possesses the potential for influencing other immunomodulators.
The combined effects of dietary proteins and fish oil on cholesterol metabolism in rats of different ages
Authors: Choi Yong‐Soon , Ikeda Ikuo , Sugano Michihiro
Published: December 2006

Male Sprague‐Dawley rats at the ages of four weeks and nine months were fed purified diets containing 20% proteins either as casein (CAS), milk whey protein (WHY), or soybean protein (SOY) with 5% sardine oil for four weeks. The hypocholesterolemic effect of SOY was not statistically evident as compared to milk proteins at both ages, although serum cholesterol tended to be low in the SOY groups. A significant agedependent increase in serum cholesterol was observed in all dietary groups. Liver cholesterol concentrations were comparable in young rats, whereas in adults they were significantly lower in the SOY than in the CAS or WHY groups. At both ages, the activity of liver 3‐hydroxy‐3‐methylglutaryl coenzyme A reductase tended to be higher in the SOY than in the other groups. Fecal steroid excretion was significantly higher in rats fed SOY than those fed either CAS or WHY, especially in adult rats. Significant age‐ and dietary protein‐effects were observed in fatty acid profiles of liver microsomal phospholipids. Thus, the effects of dietary proteins on various lipid parameters were essentially maintained even when fish oil served as the source of dietary fat.
Fatty acid composition of umbilical arteries and veins: Possible implications for the fetal EFA‐status
Authors: Hornstra G. , van Houwelingen A. C. , Simonis M. , Gerrard J. M.
Published: December 2006

Fatty acid compositions were determined of phospholipids, isolated from umbilical arteries and veins, obtained from Dutch neonates after vaginal delivery, terminating normal pregnancy. The fatty acid profiles of the cord vessels were characterized by the absence of eicosapentaenoic (timnodonic) acid, a low (2–3%) content of linoleic acid and reasonable amounts of arachidonic acid (10–15%) and docosahexaenoic (cervonic) acid (3–5%). Significant amounts of Mead acid (1–4%) and its direct elongation product (0.5–2%) were also observed. In each cord, the efferent blood vessels contained significantly more Mead acid and other fatty acids of the oleic acid (n−9) family and less fatty acids of the linoleic (n−6) and linolenic (n−3) families than the afferent blood vessel. This indicates that the essential fatty acid (EFA) status of ‘downstream’ neonatal tissue may be marginal. No signs of EFA‐deficiency were observed in endothelial and smooth muscle cells in culture, or in blood vessels from adults. In all cords 22∶5(n−6) was significantly higher in the artery compared to the vein, whereas for all other (n−6) fatty acids this difference was negative. Since the synthesis of 22∶5(n−6) is known to be stimulated when the required amount of cervonic acid, 22∶6(n−3), is too low, our observations also suggest that the cervonic acid status of the neonates investigated was not optimal. Further studies are in progress to relate these findings to maternal EFA status and complications of pregnancy.
Application of selective ion monitoring to the analysis of molecular species of vegetable oil triacylglycerols separated by open‐tubular column GLC on a methylphenylsilicone phase at high temperature
Authors: Ohshima Toshiaki , Yoon Hyung‐Sik , Koizumi Chiaki
Published: December 2006

Analyses of the molecular species of authentic triacylglycerols and of soybean triacylglycerols, which were separated on a fused silica open‐tubular column coated with a methylphenylsilicone gum stationary phase, were carried out by selective ion monitoring mass spectrometry. It was determined that peak assignments could be made by selecting certain characteristic ions with the same retention time on the SIM profile, that is, three ions of the type RCO+ corresponding to the fatty acyl residues (R1CO+, R2CO+ and R3CO+) and the corresponding three M‐acyl ions ([M‐OCOR1]+, [M‐OCOR2]+ and [M‐OCOR3]+ instead of the molecular ion. The yield of [RCO‐1]+ and [RCO‐2]+ and relating these to the unsaturated fatty acyl residues is inconvenient for an exact peak assignment. The SIM method was further applied to the peak assignment of the triacylglycerols from palm, cottonseed and safflower oils and certain new fatty acid combinations are proposed.
Sialylation of lacto‐N‐neotetraosyl ceramide by a solubilized sialyltransferase(s) from chicken skeletal muscle: Effect of phosphatidylcholine and sphingomyelin
Authors: Dasgupta Somsankar , Chien Jaw‐Long , Hogan Edward L.
Published: December 2006

The sialytransferase(s) that transfers sialic acid to lacto‐N‐neotetraosylceramide and other glycosphingolipids with a galactose nonreducing terminus has been successfully solubilized from embryonic chicken skeletal muscle. The enzyme can be stored in 50 mM HEPES (pH 6.8), 1% Triton CF‐54, and 20% glycerol at −70°C for as long as six months. Addition of phosphatidylcholine or sphingomyelin (0.167%) readily reactivates the stored inactive enzymes and such activity persists for about two weeks at 0°–4°C with the peak activity occurring at 1 to 2 days. Sphingomyelin from chicken muscle, which contains mainly C16∶0 and C18∶0, is 2.1‐fold more effective than bovine brain sphingomyelin at the same concentration (0.4%).
Lack of effects oftrans fatty acids on eicosanoid biosynthesis with adequate intakes of linoleic acid
Authors: Zevenbergen J. L. , Haddeman E.
Published: December 2006

The minimum requirement of linoleic acid to prevent effects of dietary C18trans fatty acids on eicosanoid biosynthesis in rats was assessed. In a first experiment, six groups of animals were fed diets with a high content oftrans fatty acids [20% of energy (en%)], and increasing amounts of linoleic acid (0.4 to 7.1 en%). In a second experiment, four groups of rats were fed diets designed to comparetrans fatty acids with saturated andcis‐monounsaturated fatty acids of the same chain length at the 2 en% linoleic acid level. After 9–14 weeks the biosynthesis of prostacyclin by pieces of aorta and the biosynthesis of hydroxy‐heptadecatrienoic acid and 12‐hydroxy‐eicosatetraenoic acid by platelets were measured. The fatty acid compositions of aorta phospholipid and platelet lipid were also determined. Both the prostacyclin‐production by aorta pieces and the production of hydroxy‐heptadecatrienoic acid and 12‐hydroxy‐eicosatetraenoic acid by platelets appeared to be a linear function of the arachidonic acid level in aorta phospholipid and platelet lipid, irrespective of thetrans fatty acid content in the diet. This indicates thattrans fatty acids do not directly influence enzymes involved in eicosanoid biosynthesis. In a direct comparison withcis‐monounsaturated or saturated fatty acids with 2 en% linoleic acid in the diet, only a moderate reduction in arachidonic acid level in aorta phospholipids in the group fedtrans fatty acids was observed. The geometry of the double bond did not influence the arachidonic acid level in platelet lipid, although the diet rich in saturated fatty acids increased arachidonic acid levels significantly compared with all other diets. Neither prostacyclin‐production nor hydroxy‐heptadecatrienoic acid or 12‐hydroxy‐eicosatetraenoic acid‐production were significantly affected bytrans fatty acids when 2 en% linoleic acid was present in the diet. Our study indicates that in rats 2 en% linoleic acid is sufficient to prevent effects of dietarytrans fatty acids on eicosanoid synthesis.
On the specificity of a phospholipase A2 purified from the 106,000×g pellet of bovine brain
Authors: Gray N. C. C. , Strickland K. P.
Published: December 2006

Assessment has been made of the specificity of a purified phospholipase A2 from the 106,000×g pellet (microsomal fraction) of bovine grey matter which shows strong activity toward phosphatidylinositol (PI). In the first series of experiments involving the utilization as substrates of PI with different14C‐ or3H‐labeled fatty acids in the 2‐position, the purified phospholipase A2 most readily removed 16∶0 palmitic acid, followed by 18∶0 stearic acid, 18∶1 oleic acid and 20∶4 arachidonic acid. In the second series of experiments, the purified phospholipase A2 showed preferential action toward PI (100%) compared to phosphatidylcholine (PC, 62.5%), phosphatidic acid (PA, 32.6%), phosphatidylethanolamine (PE, 25.1%) and phosphatidylserine (PS, 21.5%), where each phosphoglyceride was labeled in the 2‐position with [1‐14C] oleic acid. In the third series of experiments, fatty acids were shown to cause inhibition of action of the purified phospholipase A2 on 1‐acyl, 2‐[1‐14C] oleoyl PI in the order 20∶4>18∶1>18∶0>16∶0 which is the reverse order to that just noted. In the final series of experiments, the addition of the phosphoglycerides PC, PE, PS and PA in amounts of 5 or 10 μM caused either no inhibition (PE, 2%), slight inhibition (PC, 15%) or reasonably significant inhibition (PA, 20% and PS, 40%) of action of the purified phospholipase A2 on 1‐acyl, 2‐[1‐14C]‐oleoyl PI. The pattern of specificity observed for the purified phospholipase A2 combined with its microsomal location are the expected properties of a phospholipase A2 that might function in a deacylation‐reacylation cycle for modifying the fatty acid distribution in PI.
Gas chromatographic assay of the diastereomeric composition ofall‐rac‐α‐tocopheryl acetate
Authors: Scott Clifford G. , Cohen Noal , Riggio Patrick P. , Weber Giuseppe
Published: December 2006

It has been established by an evaluation of 6 production samples ofall‐rac‐α‐tocopheryl acetate that all 4 racemates (RRS/SSR, RRR/SSS, RSR/SRS and RSS/SRR) are consistently present in equimolar amounts (SD<0.3, RSD<1.2%). An analysis of variance indicated variance due to signal noise to be consistent within a sample run but to vary from day to day. Variance due to area measurement was greater for the first and last eluted racemates than for the second and third. Peak width and asymmetry were found to be extremely sensitive to sample loading and, even within acceptable limits for good quantitation, the distortion was sufficient to give the elution profile the appearance of a sample composed of 4 components in unequal proportions increasing according to the order of elution.
A convenient method for the preparation of asialo‐GM1
Authors: Kasai Noriyuki , Sillerud Laurel O. , Yu Robert K.
Published: December 2006

A convenient and efficient procedure has been devised for the large‐scale preparation of asialo‐GM1 from bovine brain gangliosides. The procedure relies on the complete desialylation of brain ganglio‐sides, consisting primarily of GM1, GD1a, GD1b and GT1b, by mild formic acid hydrolysis (0.1 N, 100 C; 2 hr). Following the hydrolysis step, asialo‐GM1 can be isolated and purified by Folch partitioning and Iatrobeads column chromatography, with an overall yield of more than 50%.
Oral contraceptive and platelet lipid biosynthesis in female rats: Dose‐response relationship
Authors: Ciavatti M. , Davenas E. , Michel G. , Renaud S.
Published: December 2006

Female rats were treated with different doses of an oral contraceptive (ethinyl estradiol + lynestrenol) and lipid biosynthesis was studied in blood platelets by acetate incorporation into different fractions separated by thin layer chromatography. A marked increase in lipid biosynthesis was observed, especially in the sterol fractions (cholesterol and lanosterol‐dihydrolanosterol). It was dose‐dependent, observed after a lag‐phase, maximal in 3 days and normalized in 8 days. Thus, the oral contraceptive studied here appears to modify platelet lipid biosynthesis for the entire life of the platelets.
Comparison of bile acid synthesis determined by isotope dilution versus fecal acidic sterol output in human subjects
Authors: Duane William C. , Holloway David E. , Hutton Scot W. , Corcoran Patricia J. , Haas Nancy A.
Published: December 2006

Fecal acidic sterol output has been found to be much lower than bile acid synthesis determined by isotope dilution (J. Lipid Res. 17: 77, 1976). Because of this confusing discrepancy, we compared these 2 measurements done simultaneously on 13 occasions in 5 normal volunteers. In contrast to previous findings, bile acid synthesis by the Lindstedt isotope dilution method averaged 16.3% lower than synthesis simultaneously determined by fecal acidic sterol output (95% confidence limit for the difference −22.2 to −10.4%). When one‐sample determinations of bile acid pools were substituted for Lindstedt pools, bile acid synthesis by isotope dilution averaged 5.6% higher than synthesis by fecal acidic sterol output (95% confidence limits −4.9 to 16.1%). These data indicate that the 2 methods yield values in reasonably close agreement with one another. If anything, fecal acidic sterol outputs are slightly higher than synthesis by isotope dilution.
Metabolism of malonaldehyde in vivo and in vitro
Authors: Siu G. M. , Draper H. H.
Published: December 2006

The metabolism of malonaldehyde (MA) was investigated in vivo using male Wistar rats and in vitro using rat liver mitochondria. Twelve hr after intubation with [1,3‐14C] MA, 60–70%, 5–15% and 9–17% of administered radioactivity was recovered in expired CO2, feces and urine, respectively. In rats intubated with [1,2‐14C] acetate, the corresponding values were 68–82%, 1–2% and 2–3%.14CO2 evolution was initially slower after14C‐MA administration than after14C‐acetate administration and more radioactivity was excreted in the feces and urine. In vitro experiments using [1,3‐14C] MA showed that MA is metabolized primarily in the mitochondria via reactions involving O2 utilization and14CO2 production. The apparent Km and Vmax were 0.5 mM and 9.3 nmol/min/mg protein for O2 uptake, respectively, and 2.0 mM and 2.4 nmol/min/mg protein for14CO2 production. Addition of malonic acid to mitochondrial incubates at concentrations inhibitory to succinate dehydrogenase did not affect MA‐induced O2 uptake but enhanced14CO2 production from14C‐MA.14C‐Acetate appeared to be the major accumulating metabolite in rat liver mitochondrial preparations following a 120‐min incubation with14C‐MA. A probable biochemical route for MA metabolism involves oxidation of MA by mitochondrial aldehyde dehydrogenase followed by decarboxylation to produce CO2 and acetate.