bluuebunny/crossref_metadata_2025 huggingface dataset:
Fatty acids and fatty alcohols of wax esters in the orange roughy: Specific textures of minor polyunsaturated and branched‐chain components
Authors: Takagi Toru , Itabashi Yutaka , Aso Shingo
Published: November 2006

Open‐tubular gas chromatography was carried out on fatty acids and alcohols obtained from wax esters of the orange roughy,Hoplostethus atlanticus, caught at sea off New Zealand. The major (above 5%) components were 16∶1(n−7), 18∶1(n−9) and (n−7), 20∶1(n−9) and (n−7), and 22∶1(n−11, n−13) as fatty acids, and 16∶0, 18∶0, 18∶1(n−9), 20∶1(n−9) and (n−7), and 22∶1(n−11, n−13) as fatty alcohols. The total percentages of the minor components were 10% in the acids and 26% in the alcohols. The 22∶1/20∶1 ratio of the fatty alcohols obtained in this study was less than 1.0, although the ratio for the Atlantic orange roughy has been reported as being greater than 1.0. The contents of polyenes were as low as 2.48% in the acids and 0.95% in the alcohols, but their compositions showed some specific features. The percentages of the C16−C22 dienes in the total polyenes were remarkably high, 57.7% of these acids and 53.1% of these alcohols. The most important dienes were 18∶2(n−6) in the acids and 20∶2(n−6) in the alcohols.
The monounsaturated acyl‐ and alkyl‐moieties of wax esters and their distribution in commercial orange roughy (Hoplostethus atlanticus) oil
Authors: Body Denis R. , Johnson Cecil B. , Shaw G. John
Published: November 2006

Wax esters were isolated from commercial orange roughy (Hoplostethus atlanticus) oil by column chromatography and fractionated by argentation thin layer chromatography. Following transesterification, the resultant fatty acid methyl esters and fatty alcohols were analyzed by gas chromatography. both acyl‐ and alkyl‐moieties were mainly of the monoene structure within the 16∶1–22∶1 range. After derivatization, the positions of the double bonds of even numbered fatty acid and fatty alcohol isomers were located by chromatography‐mass spectrometry and compared.

Results of these positional analyses indicate that the primary desaturation reactions takes place in the Δ9 position of pre‐existing (C14 to C24) acyl chains. It is proposed that acyl components from 18∶1 are subjected to chain elongation to form a mixture of 24∶1 isomers as the final product. Apart from the 24∶1 acyl moiety of the wax esters, in which the double bond was almost exclusively in the Δ15 position, de novo biosynthetic reactions on acids and alcohols appear to yield related acyl‐ and alkyl‐moieties of resynthesized wax esters.
GSH‐dependent inhibition of lipid peroxidation: Properties of a potent cytosolic system which protects cell membranes
Authors: Gibson Donald D. , Hawrylko Josephine , McCay Paul B.
Published: November 2006

Properties of a heat labile, nondialyzable cytosolic factor which prevents lipid peroxidation in membranous organelles are described. The factor is present in liver and other animal tissues, and its capacity to inhibit lipid peroxidation in membranes subjected to oxidative stress is greatly potentiated by glutathione (GSH), although GSH by itself has no inhibitory effect on lipid peroxidation. The data obtained thus far indicate that one or more sulfhydryl groups associated with the factor is required for the inhibition. The mechanism by which lipid peroxidation is inhibited must involve prevention of initiation of peroxidation in the membranes, presumably by a process requiring one or more sulfhydryl groups associated with the heat labile factor. The latter appears to be protected by GSH while the factor is exerting its inhibitory effect on lipid peroxidation. The factor is not one of the known GSH‐dependent enzymes, and appears to be a potent and ubiquitous system for stabilizing cell membranes against oxidative damage.
An improved assay for cholesterol 7α‐hydroxylase activity using phospholipid liposome solubilized substrate
Authors: Junker Louis H. , Story Jon A.
Published: November 2006

A persistent problem in measurement of cholesterol 7α‐hydroxylase (7α‐OHase) activity by isotope incorporation has been solubilization of cholesterol substrate. Solubilization with Tween 20, for example, resulted in a 75% reduction in 7α‐OHase activity after a 60 min incubation of substrate with microsomes. Incorporation of cholesterol substrate into small, unilamellar phospholipid vesicles (liposomes) prevented this effect, resulting in a 50% increase in activity over the same 60 min incubation at optimal concentrations. Using cholesterol in liposomes as substrate, standard assay conditions were determined to be: preparation of liposomes with 180 μM cholesterol substrate and 0.5 mg phospholipid/assay; incubation of these liposomes with 0.5 mg microsomal protein at 37 C for 60 min; addition of a NADPH generating system to start the reaction, and incubation at 37 C for 30 min before stopping the reaction and determining the amount of 7α‐hydroxycholesterol formed. In addition to preventing the detergent‐related inhibition of the enzyme, liposome‐solubilized substrate also reduced the variation among replicates from a coefficient of 45% with Tween 20 to 4.2% with phospholipid. This method provides a sensitive and reliable alternative to methods which require more sophisticated equipment and allows total control of substrate concentration in a form readily accessible to the enzyme.
Norflurazon—An inhibitor of essential fatty acid desaturation in isolated liver cells
Authors: Hagve Tor‐Arne , Christophersen Bjørn O. , Boger Peter
Published: November 2006

Norflurazon is a herbicide known to inhibit carotene biosynthesis and linolenic acid biosynthesis in plants. In the present work, the effect of norflurazon on the metabolism of essential fatty acids was studied in isolated rat liver cells and in rat liver microsomes, incubated with [1‐14C] labeled linolenic acid (18∶3, n−3), dihomogammalinolenic acid (20∶3, n−6) and eicosapentaenoic acid (20∶5, n−3). Norflurazon (0.1 mM, 1.0 mM) was found to inhibit essential fatty acid desaturation. The Δ6 desaturation is inhibited more efficiently than the Δ5 and Δ4 desaturation. The chain elongation of essential C18 fatty acids to their C20 and C22 homoglogs was not inhibited by norflurazon.
Enhancement of eicosaenoic acid lipoxygenation in human platelets by 12‐hydroperoxy derivative of arachidonic acid
Authors: Croset Martine , Lagarde Michel
Published: November 2006

Human platelet lipoxygenase activity toward several eicosaenoic acids was measured in intact cells as well as in subcellular fractions (cytosol and membranes). In whole platelets, the lipoxygenation of eicosaenoic acids was enhanced greatly by high concentrations of aspirin, which partially inhibit the peroxidase activity associated with the pathway. The lipoxygenation also was increased by arachidonic acid (AA) or its lipoxygenase product, 12‐hydroxyperoxy‐eicosatetraenoic acid (12‐HPETE). Similarly, prostanoid precursors, dihomogammalinolenic (DHLA) and eicosapentaenoic (EPA) acids also were better converted by cyclooxygenase in the presence of AA or 12‐HPETE. Among the eicosaenoic acids tested, EPA oxygenation was affected most.

Using cytosol or membranes as the lipoxygenase source instead of whole cells led to completely different results. AA exerted a competitive inhibition upon the other eicosaenoic acid oxygenation except that of EPA, for which a dual effect of AA was observed. This makes questionable the use of platelet subfractions for investigating lipoxygenase activity.

We conclude that platelet lipoxygenation of eicosaenoic acids appears peroxide‐dependent, especially for apparent poor substrates like EPA. This might be relevant in respect to 12‐HPETE, which is the main hydroperoxy derivative to be produced during platelet activation.
Non‐soluble dietary fiber effects on lipid absorption and blood serum lipid patterns
Authors: Kies Constance
Published: November 2006

Generalized effects of dietary fiber on lipid absorption and blood serum lipid patterns of humans have not been defined and may not even exist. The term dietary fiber covers a wide variety of materials with different chemical and physical characteristics. The ability of pectins and mucilages, often classed as soluble fibers, to lower blood and liver lipids has been demonstrated repeatedly and consistently. However, demonstrated hypolipidemic effects of feeding such non‐soluble fibers as cellulose, hemicellulose and bran are by no means consistent. On the basis of pooled data, it appears that hypolipidemic response or non‐response of humans to inclusion of non‐soluble fibers in diets is in part related to the degree of fecal bulking as a result of in vitro water holding capacity and in part related to pre‐study blood serum lipid levels of the individual subjects.
Effect of moderate to very low fat defined formula diets on serum lipids in healthy subjects
Authors: Snook Jean T. , DeLany James P. , Vivian Virginia M.
Published: November 2006

Serum total cholesterol, high density lipoprotein (HDL) cholesterol, and triglyceride levels were studied in healthy male and female subjects consuming for one‐week periods a diet of conventional food (CF) providing 42% of energy as fat, principally butter fat, and then in random order nutritionally complete, defined formula diets of moderate (32%) to very low (1%) fat content. Compared to CF, the formula with 32% of energy as corn oil lowered serum cholesterol by 25% and the ratio of total to HDL‐cholesterol by 13%. Low (9%) and very low (1–3%) fat formulas reduced HDL‐cholesterol by as much as 40%, raised the total: HDL‐cholesterol ratio by about 20% and raised serum triglyceride levels by as much as 100%. When low and very low fat formulas were ingested for three weeks, these effects persisted although maximal responses occurred during the first week. These results demonstrated that a moderate fat formula diet with a high P/S ratio had a more favorable effect on serum lipid levels than various low fat formulas. Low fat conventional food diets should be studied in long‐term controlled metabolic experiments before such diets are recommended to the general population for coronary heart disease or cancer prevention.
Cutin acids: Synthesis and mass spectrometry of methyl 16‐hydroxy‐7‐oxo‐, 16‐hydroxy‐8‐oxo‐, 16‐hydroxy‐9‐oxo‐, 16‐hydroxy‐10‐oxo‐ and 7,16‐, 8,16‐, 9,16‐ and 10,16‐dihydroxyhexadecanoates
Authors: Tulloch A. P.
Published: November 2006

Methyl esters of 8 16‐carbon acids which occur in cutin of plants have been synthesized from methyl 16,17‐dihydroxy‐7‐oxo‐ and 16,17‐dihydroxy‐9‐oxoheptadecanoates. 16‐Hydroxy‐7‐oxo‐ and 16‐hydroxy‐9‐oxohexadecanoates were prepared by lead tetraacetate cleavage followed by sodium triacetoxyborohydride reduction; 16‐hydroxy‐8‐oxo‐ and 16‐hydroxy‐10‐oxohexadecanoates were prepared by successive ketalization, ester reduction, diol cleavage, acylation, oxidation and methanolysis. Dihydroxy esters were prepared by reduction of oxo esters with sodium borohydride. Mass spectra of TMS ethers of the esters, of pyrrolides and of TMS esters of pyrrolidides have been compared. Mass spectra of mixtures of hydroxyoxo derivatives and of dihydroxy derivatives show that correction factors are required for quantitative analysis, particularly when 7‐substituted isomers are present.
Partition of ketone bodies into cholesterol and fatty acids in vivo in different brain regions of developing rats
Authors: Yeh Yu‐Yan
Published: November 2006

The proportions of labeled ketone bodies and glucose incorporated into cholesterol and fatty acids in different regions of the brain in developing rats were compared. In cerebrums of 15‐ and 18‐day‐old rats, the ratios of dpm cholesterol/dpm fatty acids incorporated from [3‐14C] acetoacetate and [3‐14C] β‐hydroxybutyrate ranged from 0.4 to 0.7, or 50 to 100% higher than values obtained with [U‐14C] glucose. Much higher ratios were obtained with younger animals: from 1 to 12 days of life, the values ranged from 1.0 to 1.3 with [3‐14C] β‐hydroxybutyrate as substrate, and, from 1 to 5 days, with [3‐14C] acetoacetate, they were 1.0 or greater. During the first 12 days of life, the ratios resulting from administration of [U‐14C] glucose were 0.4–0.7. Clearly, a greater proportion of acetoacetate and β‐hydroxybutyrate was incorporated into cholesterol during the first week of life than the remaining suckling period. Like cerebrum, other brain regions (i.e., cerebellum, midbrain, brain stem and thalamus) yielded higher ratios of dpm cholesterol/dpm fatty acids from [3‐14C] β‐hydroxybutyrate during the first 12 days of life than on day 17. Brain stem was the most active region for lipid synthesis, and had the highest dpm cholesterol/dpm fatty acid ratio. Since active synthesis of cholesterol from ketone bodies during the early postnatal period coincides with a period of rapid brain growth, the results indicate that ketone bodies are more important early in the suckling period as sources of cholesterol for brain growth.
Effect of diet composition and fasting on lipogenesis in lean and polygenic obese mice
Authors: Hennig Bernhard , Sutherland Thomas M. , Mathias Melvin M. , Smith Barbara A.
Published: November 2006

A line of mice was developed which exhibited spontaneous obesity when fed commercial laboratory ration low in fat content. Obese mice were compared to a nonobese related line to determine whether energy source in the diet would affect onset of obesity. Experimental diets‐beef tallow (38% of calories as beef fat and 2% as corn oil), corn oil (40% corn oil) or low‐fat (2% corn oil)‐were instituted ad libitum at the time of weaning. When the mice reached 6 months of age, lipogenesis was investigated by injecting intravenously3H2O and glucose‐U‐14C.3H2O and glucose‐U‐14C incorporation into fatty acids of fed mice was greater for obese than for lean mice. Fatty acid synthesis was inhibited by high‐fat diets compared to low‐fat diet in both lines. Of the 2 high‐fat diets, the corn oil diet inhibited fatty acid synthesis about twice as much as beef tallow diet. There was no line effect on tritium incorporation into cholesterol. Cholesterol synthesis from glucose‐U‐14C was greater in obese than lean mice. Diets had no effect on tritium and glucose‐U‐14C incorporation into cholesterol. Fasting reduced fatty acid synthesis in all mice, but total body fatty acid synthesis was not affected by lines or dietary treatment under fasted conditions. These data suggest that degree of lipogenesis, in part, explains obesity. A failure of inhibition of lipogenesis or an enhanced efficiency in fat deposition by feeding beef tallow compared to corn oil diet may explain the fact that lean mice fed the beef tallow diet tended to be more obese that lean mice fed corn oil or low‐fat diets.
Hormonal regulation of medium chain fatty acid synthesis by mouse mammary gland explants
Authors: Borst David W.
Published: November 2006

Explants of pregnant mouse mammary tissue were cultured in media supplemented with various hormones. During the last few hours of culture, explants were labeled with [14C] acetate. Fatty acid synthesis by the tissue was analyzed using reverse phase thin layer chromatography, and incorporation of radioactivity into the medium chain fatty acid (MCFA) fraction was calculated as total MCFA per mg tissue fresh weight and as a percentage of the total fatty acid radioactivity (%MCFA). After 48 hr of culture, explants had an elevated %MCFA synthesis only when exposed to media containing insulin, cortisol and prolactin, confirming previous reports. Increasing doses of prolactin (maximal response at 300 mg/ml) caused a coordinate rise in both %MCFA synthesis and total MCFA synthesis per mg fresh weight. Epithelial cells isolated from explants after culture for 48 hr with insulin, cortisol and prolactin showed an elevated %MCFA synthesis compared to cells from explants cultured with insulin and cortisol alone, indicating that hormonal stimulation of mammary explants causes a change in the chain length of fatty acids synthesized by mammary epithelial cells. The specificity of the explant response to prolactin was tested with other hormones: FSH and calcitonin had no effect, whereas bovine growth hormone showed activity only at high concentration. Progesterone and 17β‐estradiol also had no effect. The analysis of MCFA synthesis provides another means of (a) assessing hormonal action upon mammary tissue, and (b) evaluating the biological activity of prolactin.
The influence of linoleic acid intake on membrane‐bound respiratory activities
Authors: Abuirmeileh N. M. , Elson C. E.
Published: November 2006

The fatty acid composition of subcellular membranes, like that of depot fats, can be altered by dietary manipulation. Most attention has been directed toward the effects of feeding an essentialfatty‐acid‐free diet. We chose to examine some responses generated by the feeding of a dietary fat containing a disproportionately high level of an essential fatty acid. Rats were fed diets formulated with beef tallow (BT) to provide 4% (P/S, 0.2) or safflower oil (SO) to provide 24% (P/S, 7.6) of total energy as linoleic acid. Lipids isolated from hepatic mitochondria of rats fed the SO diet contained, in relative terms, 85% more unsaturated bonds. Mitochondria isolated from livers of rats fed either diet were tightly coupled. When all aspects of oxidative metabolism examined in this report are considered, mitochondria of SO group origin exhibited greater oxidative activities but lower ADP/O ratios than did BT mitochondria. Our hypothesis is that the perturbed state of the membrane‐bound phospholipids initiates a remodeling‐response through which an intramitochondria source of ADP is generated to support state‐3 respiratory activity.
Gangliosides of bovine optic nerve
Authors: Das Salil K. , McCullough Melba S.
Published: November 2006

Gangliosides from bovine optic nerve were analyzed. The optic nerve contained 129, 98, 97, 80, 31 and 12 μg of GM1, GD1a, GD1b, GT1b, GD3 and GQ1 gangliosides, respectively, per g of tissue wet wt. These 6 gangliosides altogether contributed 97% of the total sialic acid. GM3 and GM2 gangliosides contributed the remaining 3% of total sialic acid. Stearoyl (18∶0) was the predominant acyl group (61–76%) in all gangliosides. There was a marked variation in acyl group composition between GT1 and most of the other major gangliosides except GD3. In comparison to the other gangliosides, GT1 contained a lower proportion of the stearoyl group and a higher proportion of the oleoyl, nervonoyl and the long chain acyl groups. Both GT1 and GD3 gangliosides contained proportionately higher levels of long chain acyl groups (20∶0→24∶0) than did other gangliosides. GD3 gangliosides showed 2 bands on thin layer chromatography, and the upper band was more distinct than the lower band.
Nitric‐oxide myoglobin as an inhibitor of lipid oxidation
Authors: Kanner Joseph , Ben‐Gera Itamar , Berman Shura
Published: November 2006

The effect of nitric‐oxide myoglobin (MbNO) on lipid oxidation was studied in linoleate and β‐carotene‐linoleate aqueous model systems and compared with that of metmyoglobin (MMb) and oxymyoglobin (MbO2) in short‐ and long‐term reactions. While MMb and MbO2had a clear prooxidative effect, MbNO, under the same conditions, acted as an antioxidant. The specific antioxidative activity of MbNO was maintained even in the presence of prooxidants such as hemeproteins. The significance of the conversion of MbO2and MMb into an antioxidant during the curing process is discussed.
Fatty acid and sterol composition of ungerminated spores of the vesicular‐arbuscular mycorrhizal fungus,Acaulospora laevis
Authors: Beilby J. P.
Published: November 2006

The fatty acids and sterols of ungerminated chlamydospores of the vesicular‐arbuscular (VA) endophyteAcaulospora laevis were examined by gas chromatography and mass spectrometry. The total lipid content of the spores was 45.5% of the spore dry weight. Predominant fatty acids were palmitoleic (52.5%), palmitic (25.5%) and oleic (7.4%). Minor fatty acids consisted of a range of (n−3) and (n−6) polyunsaturated acids. The occurrence of (n−3) polyunsaturated fatty acids is rare in fungi of the order Mucorales. Three sterols were identified as 24‐ethylcholesterol (79.9%), cholesterol (11.0%) and 24‐methylcholesterol (9.2%). No ergosterol was detected. Lipids of the chlamydospores ofA. laevis are compared with those ofGlomus caledonius.
Altered fatty acid desaturation and microsomal fatty acid composition in the streptozotocin diabetic rat
Authors: Faas Fred H. , Carter William J.
Published: November 2006

Streptozotocin diabetes in the rat diminishes the synthesis of both monounsaturated and polyunsaturated fatty acids. Rat liver microsomal fatty acid composition and fatty acid desaturation were studied in the streptozotocin diabetic rat. The major alterations in fatty acid composition found in the diabetic rat were decreased proportions of palmitoleic, oleic and arachidonic acids and an increased proportion of linoleic and docosahexaeneoic acids. These findings, other than the increased docosahexaeneoic acid, probably result from the diminished liver microscomal δ9 and δ6 desaturase activities found in these animals. These changes are not due to the diminished weight gain of the diabetic animals since restricting food intake of control animals to achieve a similar weight gain failed to reproduce either the changes in fatty acid composition or the decrease in fatty acid desaturation. The increased food intake of the diabetic animal may contribute to the altered proportions of linleic and arachidonic acids since limiting food intake in diabetic animals to that of normal controls diminished the magnitude of these changes. Insulin therapy for 2 days not only reverses and overcorrects the diminished desaturase activities, but likewise reverses and overcorrects the altered fatty acid composition, with the exception of the diminished arachidonic aicd levels which are further decreased following insulin therapy. These findings strongly suggest that most of the changes in fatty acid composition in the diabetic rat are indeed caused by the diminished fatty acid desaturase activities.
Activity of myocardial lipase using natural edible oils as substrates
Authors: Vajreswari A. , Tulpule P. G.
Published: November 2006

Rat heart homogenates were tested for their lipolytic activity toward synthetic and natural substrates such as edible oils. Triolein was hydrolyzed very efficiently by myocardial lipase whereas trierucin was not cleaved by the enzyme. Among the natural substrates, safflower oil, which has the highest degree of unsaturation, was hydrolyzed to a greater extent than the other oils. Mustard oil rich in erucic acid formed a poor substrate for the myocardial lipase.
The identity of the cholesteryl esters in human milk
Authors: Clark R. M. , Ferris A. M. , Fey N. , Hundrieser K. E. , Jensen R. G.
Published: November 2006

Milk samples were collected from 11 mothers who were at least 4 weeks postpartum. The amounts of fat and the fatty acid compositions of cholesteryl esters (CE) and triacylglycerols (TG) in the milk were determined. The mean concentration of total milk lipid was 3.01 gm/100 ml of milk±.42 SD. The major fatty acids esterified with CE and TG were 16∶0,cis 18∶1 and 18∶2. The patterns were similar except for a greater proportion ofcis 18∶1 in the CE. The majortrans fatty acid detected was the 18∶1 isomer which accounted for 4.48% of the TG fatty acids and 2.96% of the CE fatty acids.
Homeostasis of mucosal cholesterol in the small intestine of the rat
Authors: Blumer A. , Watt S. M. , Simmonds W. J.
Published: November 2006

This study was undertaken to investigate the capacity of the intestinal mucosa to maintain a constant cholesterol content under conditions where mucosal uptake or cholesterol transport into the lymph were manipulated. Two series of bile‐diverted unanaesthetised rats were infused intraduodenally with saline, triolein emulsified with Pluronic F68, or taurocholate with or without added tomatine. Pluronic F68 is a nontoxic detergent which promotes mucosal uptake of polar lipids but not cholesterol. Tomatine is a cholesterol‐binding saponin. One series of rats was used for measuring mucosal cholesterol content, DNA and protein after the test infusions. A second series of rats had the thoracic lymph duct cannulated but otherwise remained the same as the first series. The second series was used for measuring the effect of the different infusions on mass cholesterol output into lymph. Mucosal cholesterol content of rats that were not fed decreased with bile‐diversion and was restored with taurocholate infusion. This suggested a contribution of luminal cholesterol to the mucosal cholesterol pool. However, evidence for a contribution from the lumen was provided by only one of two groups of rats given infusions which did not promote mucosal uptake of cholesterol. First, addition of tomatine to the taurocholate infusate prevented both the increase in lymph output of cholesterol and the increased mucosal cholesterol content shown in rats given taurocholate alone. Second, in another group of rats in which mucosal uptake of cholesterol was prevented, i.e. in rats given Pluronic F68‐triolein emulsions, the increased fat absorption was accompanied by a marked increase in cholesterol output into lymph without a concomitant decrease in mucosal cholesterol content. These results would be consistent with increased mucosal synthesis of cholesterol as a possible source of endogenous cholesterol absorbed into lymph.
Serum lipids and fatty acid composition of tissues in rats on total parenteral nutrition (TPN)
Authors: Martins F. M. , Wennberg A. , Meurling S. , Kihlberg R. , Lindmark L.
Published: November 2006

The modulating effect of energy and exogenous triglyceride supply on serum lipids and fatty acid composition of liver, tibialis anterior muscle, subcutaneous and peri‐epididymal fat was assessed in rats using Total Parenteral Nutrition (TPN). Nutrients were infused continuously for 10 days through a central vein catheter. Four levels of fat were tested: No fat, Low fat (6% non‐protein calories), Medium fat (30%) and High fat (60%), at 2 energy levels (270 kcal and 350 kcal/kg·day). An isonitrogenous supply was given to all groups as 0.9 g N/kg·day. At the highest level of fat intake (20.4 g/kg) at the high energy level triglycerides, cholesterol and phospholipids of serum were elevated. Biochemical signs of essential fatty acid (EFA) deficiency were observed as rising levels of eicosatrienoic acid and lowered concentrations of linoleic and arachidonic acid, mostly in the liver and the muscle in the No fat groups. EFA levels were reduced significantly in the No fat and Low fat groups and more pronounced at the high energy level. In conclusion, our study suggests that when energy intake is increased the EFA status becomes more critical. It seems evident that more EFA is required in absolute values when hypercaloric diets are given.
Phospholipid studies of marine organisms: New branched fatty acids fromStrongylophora durissima
Authors: Dasgupta Amitava , Ayanoglu Eser , Djerassi Carl
Published: November 2006

The phospholipids of the spongeStrongylophora durissima were analyzed. The major phospholipids present were phosphatidylethanolamine (PE), phosphatidylcholine (PC), phosphatidylserine (PS), phosphatidylglycerol (PG) and phosphatidylinositol (PI). The major fatty acid components of the phospholipids consisted of short chain (C14−C19) and very long chain (C25−C30) “Demospongic” acids. Three novel branched Δ5 monounsaturated acids,Z‐19‐methyl‐5‐pentacosenoic,Z‐19‐methyl‐5‐hexacosenoic andZ‐19‐methyl‐5‐heptacosenoic acids were encountered in the sponge. The 3‐saturated counterparts of these compounds, 19‐methylpentacosanoic, 19‐methylhexacosanoic and 19‐methylheptacosanoic acids, as well as 19‐methylpentacosanoic and 20‐methyloctacosanoic acids also are hitherto undescribed acids present in the sponge. Trace amounts of 2 very long chain acids also were detected and their structures tentatively assigned as 19,21‐dimethylheptacosanoic and 20,22‐dimethyloctacosanoic acids. The distribution of these fatty acids according to phospholipid head groups also was described.
Reduction of polyunsaturated fatty acid hydroperoxides by human brain glutathione peroxidase
Authors: Kaplan E. , Ansari K.
Published: November 2006

Glutathione peroxidase (GSHPx) activity in the normal human brain was investigated using lipid hydroperoxides as substrates. Samples were obtained from autopsied frontal gray matter of 5 normal human males with no known central nervous system (CNS) disease. Aliquots were homogenized in 0.9% NaCl‐0.5% Triton X‐100, and the supernatant solution, obtained after centrifugation at 105,000 × g, was used for GSHPx assay. Glutathione peroxidase was measured by following the oxidation of NADPH at 340 nm. Hydroperoxides of linoleic, linolenic, gamma linolenic, 11,14 eicosodienoic, homo gamma linolenic, arachidonic, docosotetraenoic and docosohexaenoic acids were prepared and used as substrates. All these hydroperoxides were reduced by the brain GSHPx system, but at different rates. Gamma linolenic and docosotetraenoic hydroperoxides were reduced rapidly, whereas the peroxides of docosohexaenoic and 11,14 eicosodienoic were reduced at the lowest rate. Arachidonic hydroperoxide had the highest affinity for the enzyme and linolenic the lowest. Our results suggest that the brain GSHPx system is capable of reducing hydroperoxides of polyunsaturated fatty acids.
Analysis of autoxidized fats by gas chromatography‐mass spectrometry. IX. Homolytic vs. Heterolytic cleavage of primary and secondary oxidation products
Authors: Frankel E. N. , Neff W. E. , Selke E.
Published: November 2006

To elucidate the genesis of volatile lipid oxidation products, thermal homolytic and acid heterolytic decomposition processes were compared. Secondary oxidation products were decomposed thermally (200 C), and the volatiles formed were identified by capillary gas chromatography‐mass spectrometry (GC‐MS). Oxidation products also were decomposed in the presence of HCl‐methanol, and the resulting dimethyl acetals were identified by GC‐MS. The volatile thermal decomposition products were those expected by homolytic β‐scission on both sides of the hydroperoxide group. No dialdehydes were identified under our thermal decomposition conditions. In contrast, the acetals formed by acid decomposition were those expected by selective heterolytic scission between the hydroperoxide group and the allylic double bond. Dialdehydes identified from acid decomposition of cyclic peroxides and dihydroperoxides included malonaldehyde and 2,4‐hexadienedial.
The purification of fatty acid methyl esters by high pressure liquid chromatography
Authors: Bascetta Emanuele , Gunstone Frank D. , Scrimgeour Charles M.
Published: November 2006

Procedures are described for the rapid purification of gram quantities of methyl oleate, methyl linoleate, methyl α‐ and γ‐linolenates and methyl ricinoleate from appropriate natural oils by high pressure liquid chromatography (HPLC).
Essential fatty acids in plasma, red blood cells and liver phospholipids in common laboratory animals as compared to humans
Authors: Horrobin David F. , Huang Y. ‐S. , Cunnane S. C. , Manku M. S.
Published: November 2006

Essential fatty acids were estimated in plasma, red blood cells and liver total phospholipids in rats, mice, hamsters, guinea pigs, rabbits and humans. There were large species differences, suggesting that different species levels should be borne in mind when choosing an animal for a particular study. The 2 species most susceptible to atheroma, the guinea pig and the rabbit, had very high levels of linoleic acid and low levels of linoleic acid metabolites. n−3 fatty acid levels were low in guinea pigs and rabbits and the ratio of n−3 to n−6 fatty acids also was low in the rat. Mice and hamsters had the highest n−3 levels, suggesting they may be the best species to use for studies on the roles of n−3 essential fatty acids. Mice and hamsters and, in some respect rats, were closest to humans in their fatty acid patterns.
Influence of cholesterol feeding and dietary restriction on cholesterol absorption in rabbits
Authors: Corraze G. , Lacombe C. , Nibbelink M.
Published: November 2006

Plasma cholesterol and cholesterol absorption were measured in rabbits given either a standard or cholesterol‐rich diet which were fed either ad libitum or reduced to 50% of the control ration. The results confirmed the aggravating effect of dietary restriction on the plama cholesterol response to cholesterol feeding. Hypercholesterolemia was doubled when cholesterol feeding was associated with reduced dietary intake. The percentage of cholesterol absorbed increased significantly in cholesterolfed rabbits on normal caloric ration, while dietary restriction had no effect on this parameter either with the standard or the cholesterol‐rich diet. These data indicate that the mechanisms by which plasma cholesterol increases in response to cholesterol feeding involve increased cholesterol absorption. Nevertheless the aggravating effect of dietary restriction cannot be attributed to increased cholesterol absorption.
Analyses of lipids and fatty acids in ripe roes of some Northwest European marine fish
Authors: Tocher Douglas R. , Sargent John R.
Published: November 2006

Lipid class analyses and fatty acid analyses of neutral and polar lipids were carried out on ripe roes of herring, cod, haddock, whiting, saithe, sand eel and capelin. Total lipid was 10–26% of roe dry weight. The species with the highest total lipid, sand eel and capelin, also had the highest percentage of neutral lipid in total lipid, 77% and 49% respectively. In the other species, phospholipids accounted for 62–77% of roe total lipid. Both the neutral lipids, and especially the phospholipids, of all species were very unsaturated because of high concentrations of (n−3) polyunsaturated fatty acids (PUFA), frequently amounting to 50% of the total egg lipid. Phosphatidylcholine (PC) and phosphatidylethanolamine (PE) had similar fatty acid compositions in all species, with an average ratio (n−3)/(n−6) of ca. 20∶1. Phosphatidylinositol (PI) consistently had high concentrations of 18∶0 and 20∶4 (n−6) with an average ratio of (n−3)/(n−6) of 1.8∶1. Requirements for high levels of (n−3) PUFA in the embryonic and early larval development stages of marine fish are suggested as is a special role for the 20∶4(n−6) in PI.
Sterol metabolism in the nematodeCaenorhabditis elegans
Authors: Chitwood David J. , Lusby William R. , Lozano Ruben , Thompson Malcolm J. , Svoboda James A.
Published: November 2006

The metabolism of various dietary sterols and the effects of an azasteroid on sitosterol metabolism in the free‐living nematodeCaenorhabditis elegans was investigated. The major unesterified sterols ofC. elegans in media supplemented with sitosterol, cholesterol or desmosterol included 7‐dehydrocholesterol (66.5%, 40.5%, 31.2%, respectively), cholesterol (6.7%, 52.3%, 26.9%), lathosterol (4.4%, 3.6%, 1.7%) and 4α‐methylcholest‐8(14)‐en‐3β‐ol (4.2%, 2.1%, 3.8%). Esterified sterols, representing less than 20% of the total sterols, were somewhat similar except for a significantly higher relative content of 4α‐methylcholest‐8(14)‐en‐3β‐ol (23.3%, 23.4%, 10.6%). ThusC. elegans not only removes the substituent at C24 of dietary sitosterol but possesses the unusual ability to produce significant quantities of 4α‐methylsterols. WhenC. elegans was propagated in medium supplemented with sitosterol plus 5 μg/ml of 25‐azacoprostane hydrochloride, the azasteroid strongly interfered with reproduction and motility ofC. elegans and strongly inhibited the Δ24‐sterol reductase enzyme system; excluding sitosterol, the major free sterols of azacoprostane‐treatedC. elegans were cholesta‐5, 7, 24‐trien‐3β‐ol (47.9%), desmosterol (9.4%), fucosterol (2.1%) and cholesta‐7,24‐dien‐3β‐ol (2.0%). These 4 sterols are likely intermediates in the metabolism of sitosterol inC. elegans.
Preferential metabolism of linoleic acid by five‐day‐old barley shoots
Authors: Nabors Lola A. , Morgan Marjorie S. , Newman David W. , Jaworski Jan G.
Published: November 2006

The degradation of exogenous radioactively labeled fatty acids by 5‐day‐old barley shoots was examined. [1‐14C] Linoleic acid was observed to be degraded 7 times faster than [1‐14C] oleic acid and 5 times faster than [1‐14C] palmitic acid. The pathway of degradation was determined by identifying the water‐soluble products and determined to be β‐oxidation. During a 15 min incubation, the barley shoots took up 0.91 nmol/g fresh wt of linoleic acid, of which 0.16 nmol/g fresh wt was incorporated into glutamic acid, 0.07 nmol/g fresh wt into succinic acid and 0.002 nmol/g fresh wt into carbohydrates. By 30 min, additional TCA cycle intermediates, especially malic acid, were detected. Palmitic acid and oleic acid were broken down to the same products. The rates of uptake and the distribution of label into lipids were determined. The uptake of label by the tissue was similar for all 3 fatty acid substrates. Label from linoleic, oleic and palmitic acids was found to be incorporated into similar lipids, primarily phosphatidylcholine (PC), and the extent of incorporation was comparable. Although all 3 fatty acid substrates were broken down by β‐oxidation, the reason for the more rapid degradation of linoleic acid was not established. It does not appear to be related to uptake of substrate or incorporation of label into lipids.
A possible regulatory role of squalene epoxidase in chinese hamster ovary cells
Authors: Eilenberg Haviva , Shechter Ishaiahu
Published: November 2006

Growth of Chinese Hamster Ovary (CHO) cells in the presence of 20% lipid depleted serum (LDS) for only 2 hr results in an increase in the synthesis of [14C] sterols from [14C] mevalonate and from [14C] squalene compared with cells grown under normal growth conditions in the presence of 10% fetal calf serum (FCS). This enhanced sterol synthesis increases with time of exposure of the cells to LDS. However, exposing these cells for time periods up to 42.5 hr to a growth medium containing 20% LDS did not result in enhanced [14C] sterol synthesis from [14C] 2,3‐oxidosqualene. Incubation of these cells with [14C] mevalonate resulted in the accumulation of [14C] squalene regardless of the presence of either LDS or FCS. These results suggest that squalene epoxidase is a regulatory enzyme in the cholesterol biosynthetic pathway in CHO.
Selective oxidation of steroidal allylic alcohols using pyrazole and pyridinium chlorochoromate
Authors: Parish Edward J. , Chitrakorn Sarawanee , Lowery Susan
Published: November 2006

Abastract

This paper presents a modified method for the selective oxidation of allylic alchols. Pyrazole, when used with pyridinium chlorochromate, is a mild and useful reagent system for the rapid and selective oxidation of steroidal allylic alcohols to the corresponding α, β‐unsaturated ketones. The reaction of each substrate was carried out by adding the oxidant to a dry methylene chloride solution containing pyrazole and an allylic alchol. This report is the first on the use of pyrazole to augment selective oxidation by a chronium (VI) reagent.
Analytic ultracentrifuge calibration and determination of lipoprotein‐specific refractive increments
Authors: Kahlon Talwinder S. , Adamson Gerald L. , Glines Laura A. , Lindgren Frank T. , Laskaris Marie A. , Shore Virgie G.
Published: November 2006

Accurate quantification of the major classes and subfractions of human serum lipoproteins is an important analytical need in the characterization and evaluation of therapy of lipid and lipoprotein abnormalities. For calibrating the analytic ultracentrifuge (AnUC), we routinely use a Beckman calibration wedge cell with parallel scribed lines 1 cm apart. Such a cell gives a rectangular pattern in the schlieren diagram, which determines magnification and also provides an area corresponding to an invariant refractive increment. We have independently validated this wedge calibration cell using a special boundary‐forming cell in which 1.174% sucrose is overlayered with distilled water. Comparing wedge cell area with extrapolated zero time boundary area refractive increment gives agreement to within less than 1%, corresponding to a refractive increment error of ±0.00002 Δn. Complete calibration for AnUC analysis of lipoproteins also requires accurate determination of the specific refractive increments (SRI) of the major lipoprotein classes, namely low density lipoprotein (LDL) and high density lipoprotein (HDL). These are measured in the density in which they are analyzed, i.e., 1.061 g/ml for LDL and 1.200 g/ml for HDL. Five fresh serum samples were fractionated for total LDL and total HDL and their SRI determined. Total lipoprotein mass was determined using precise CHN elemental analysis and compositional analyses. The results yielded corrected SRI of 0.00142 and 0.00135 Δn/g/100 ml for LDL and HDL. Thus, our current values using 0.00154 and 0.00149 Δn/g/100 ml underestimate LDL and HDL by 9% and 11%. Corrections of all previous LDL and HDL AnUC data can be made using appropriate factors of 1.087 and 1.106.
Plasma and lipoprotein lipid responses to four hypolipid drugs
Authors: Hazzard William R. , Wahl Patricia W. , Gagne Claude , Applebaum‐Bowden Deborah , Warnick G. Russell , Albers John J.
Published: November 2006

The responses of 14 hyperlipidemic subjects to 4 hypolipidemic agents were compared by measureing cholesterol and triglyceride in whole plasma, very low density lipoproteins (VLDL), low density lipoproteins (LDL), and high density lipoproteins (HDL) monthly for 2 months before and 3 months during treatment with each of 4 drugs: clofibrate, 2 g/d; colestipol, 20 g/d; para‐aminosalicylic acid‐ascorbate (PAS‐C), 6–8 g/d; and oxandrolone, 7.5 mg/d. Lipid responses proved to be stable by the first monthly evaluation both off and on each drug. Mean adherence was high and similar for all agents (81–92% of the prescribed dose). Clofibrate was associated with significant decreases in mean plasma cholesterol (−16%, p<.01), plasma triglyceride (−51%, p<.005), VLDL‐cholesterol (−61%, p<.005) and VLDL‐triglyceride (−61%, P<.005), while HDL cholesterol increased (+20%, p<.01), and the LDL‐cholesterol/HDL ratio declined (−24%, p<.05). Colestipol was associated with decreases in mean plasma cholesterol (−15%, p<.01) and LDL‐cholesterol (−22%, p<.05), while VLDL‐triglyceride increased (+41%, p<.05), and the LDL‐cholesterol/HDL‐cholesterol ratio declined (−25%, p<.05). PAS‐C was associated with decreases in VLDL‐cholesterol (−30%, p<.05), and VLDL‐triglyceride (−29%, p<.05), while the LDL‐cholesterol/HDL‐cholesterol ratio remained unchanged. Oxandrolone was associated with increases in mean plasma cholesterol (+7%, p<.05), LDL‐cholesterol (+45%, p<.005 [+25% excluding one subject who increased 298%]), and LDL‐triglyceride (+24%, p<.01), while decreases occurred in plasma triglyceride (−31%, p<.05), VLDL‐cholesterol (−26%, p<.05), VLDL‐triglyceride (−42%, p<.005), HDL‐cholesterol (−45%, p<.005), and HDL‐triglyceride (−43%, p<.01). The mean LDL‐cholesterol/HDL‐cholesterol ratio increased by 109% (p<.005), reflecting the reciprocal changes in LDL and HDL. Thus, while both clofibrate and colestipol were associated with significant, equivalent reductions in theoretical atherogenic risk, oxandrolone produced a net effect that was not only adverse but 4 times that magnitude, suggesting caution in its long‐term use, even for the management of hypertriglyceridemia.
Iodothyronines: Oxidative deiodination by hemoglobin and inhibition of lipid peroxidation
Authors: Tseng Yueh‐Chu L. , Latham Keith R.
Published: November 2006

Purified rat hemoglobin catalyzes the oxidative degradation of iodothyronines to form iodide and an iodine‐containing intermediate that reacts with protein. Hemoglobin also catalyzes peroxidation of linoleic acid. These observations are consistent with the reported intrinsic peroxidase activity of hemoglobin and other heme‐proteins. However, incubations containing both linoleic acid and an iodothyronine produced a surprising result: deiodination was stimulated rather than competitively inhibited. In contrast, linoleic‐acid peroxidation was inhibited by iodothyronines. Thus, low levels of iodothyronines (2.6×10−7M) are effective inhibitors of linoleic‐acid peroxidation. Thyroxine and reverse T3 were found to be more effective in this antioxidant activity than vitamin E, glutathione, ascorbic acid and DTT. Since linoleic‐acid peroxidation proceeds by a propagating free‐radical mechanism, we have concluded that iodothyronines can effectively terminate the free‐radical chain reaction to become oxidatively deiodinated. Consistent with this antioxidant mechanism, reverse T3 is effective in preserving red cell membranes as measured by the inhibition of erythrocyte hemolysis.
Restriction of maternal food intake inhibits fatty acid activation in developing rat hearts
Authors: Menon Nirmala K. , Dhopeshwarkar Govind A. , Mead James F.
Published: November 2006

We studied the effect of restricting the diet of pregnant and lactating rats on the β‐oxidation of fatty acids by the developing heart in suckling pups. Control pregnant rats were fed a stock diet ad libitum. For the experimental group, food was restricted to half of the control intake on the seventh day of pregnancy and continued through lactation. The pups on the restricted diet were significantly smaller than the controls. At postnatal days 5, 14 and 21, the β‐oxidation of [1‐14C] palmitate by heart homogenates was determined in the presence of ATP, carnitine and CoA. At day 21, the production of14CO2 was 60% lower in the group on the restricted diet. Consequently, the possibility of inhibiting activation or intramitochondrial transport of fatty acids by heart mitochondria was studied in vitro using [1‐14C] palmitate, [1‐14C] palmitoyl CoA and [1‐14C] palmitoyl carnitine. With [1‐14C]‐palmitate, the rate of14CO2 produced was 2464±317 cpm/mg protein/min for the control and 1682±91 for the restricted diet group. With [1‐14C] palmitoyl CoA and [1‐14C] palmitoyl carnitine, the oxidation rate of the experimental group was similar to control values, showing clearly that the inhibition of oxidation was from a problem with activation. A significant decrease in palmitoyl CoA synthetase activity in the heart homogenates and mitochondria of the diet‐restricted pups took place.
Inhibition of the hormone‐sensitive lipase in adipose tissue by long‐chain fatty acyl coenzyme A
Authors: Severson David L. , Hurley Brenda
Published: November 2006

The effects of free fatty acids and fatty acyl esters of coenzyme A and carnitine on the activity of a hormone‐sensitive lipase preparation made from pigeon adipose tissue were determined. Oleic acid (100 μM) resulted in a 40% inhibition of lipase activity A more potent inhibition of lipase activity was seen with long‐chain fatty acyl CoA compounds. The concentration required for half‐maximal inhibition with oleoyl CoA and palmitoyl CoA was 25–40 μM, whereas palmitoyl carnitine stimulated lipase activity. Activated lipase preparations (preincubated with Mg2+, ATP, cyclic AMP and protein kinase) were 4–6 times more sensitive to inhibition by oleoyl CoA than were nonactivated preparations. An increase in cellular levels of fatty acyl coenzyme A could, therefore, contribute to the feedback inhibition of lipolysis in adipose tissue.
Alcohol ingestion and levels of hepatic fatty acid synthetase and stearoyl‐CoA desaturase activities in rats
Authors: Rao G. Ananda , Lew Gail , Larkin Edward C.
Published: November 2006

Male Sprague‐Dawley rats were fed, ad libitum for 30 days, a fat‐free (FF) liquid diet containing 34% of the calories as ethanol or a control FF diet in which alcohol was replaced by an isocaloric amount of dextrins. The cytosolic fatty acid synthetase and the microsomal stearoyl‐CoA desaturase activities in the livers of rats fed the alcohol diet were about half of those observed in the livers of control rats. The conclusion is that chronic ethanol consumption depresses the activities of these lipogenic enzymes in the liver.