bluuebunny/crossref_metadata_2025 huggingface dataset:
Heterogeneity of molecular weight and apolipoproteins in low density lipoproteins of healthy human males
Authors: Kahlon Talwinder S. , Shore Virgie G. , Lindgren Frank T.
Published: November 2006

The molecular weights of five low density lipoprotein (LDL) subfractions from four normal healthy males were determined by analytic ultracentrifuge sedimentation equilibria. Protein content of each subfraction was determined by elemental CHN analysis, and weights of apoprotein peptides were calculated. Molecular weights in subfractions of increasing density were 2.92±0.26, 2.94±0.12, 2.68±0.09, 2.68±0,28 and 2.23 ±0,22 million Da, and protein weight percentages were 21.05, 21.04, 22.05, 23.10 and 29.10, in subfractions, 1,2,3,4 and 5, respectively. Total mean apoprotein weights for respective subfractions were 614±53,621±45, 588±9,637±83 and 645 ±62 KDa. In addition to a single apoprotein B‐100 (apo B‐100) peptide with a mean carbohydrate content of 7.1% and a molecular weight of 550 KDa per LDL particle, there may be one or more apoprotein E peptides of 34 KDa and/or apoprotein C‐III of 9 KDa. In addition, subfractions 4 and 5 may contain 3–7% apolipoprotein (a). There is considerable heterogeneity among LDL subfractions as well as within the same fraction from different individuals. This heterogeneity may relate to differences in origin, metabolism and/or atherogenicity as a result of their content of apoproteins other than apo B‐100.
Effects of a platelet‐activating factor antagonist, CV‐6209, on Gastric mucosal lesions induced by ischemia‐reperfusion
Authors: Yoshikawa Toshikazu , Takahashi Shuji , Naito Yuji , Ueda Shigenobu , Tanigawa Toru , Yoshida Norimasa , Kondo Motoharu
Published: November 2006

Recent research was shown that oxygen‐derived free radicals are involved in the pathogenesis of various diseases, including ischemia‐reperfusion injury. We have also reported that oxygen‐derived free radicals and lipid peroxidation may play an important role in gastric mucosal injury induced by ischemia‐reperfusion. The hypoxanthinexanthine oxidase system and neutrophils are considered important sources of oxygen‐derived free radicals in this process. In recent years, it also has been shown that serum platelet‐activating factor (PAF) levels increased during ischemia‐reperfusion, and that induction of superoxide generation by neutrophils is one of the important biological effects of PAF. In the present study, we examined the effect of CV‐6209, a specific PAF receptor antagonist, on gastric mucosal injury induced by ischemia‐reperfusion, to shed some light on the possible involvement of PAF in such lesions. CV‐6209 significantly attenuated the gastric mucosal injury induced by ischemia‐reperfusion, and inhibited both an increase of thiobarbituric acid reactive substances and a decrease of α‐tocopherol in gastric mucosa after ischemia‐reperfusion. However, CV‐6209 had no effect on gastric mucosal blood flow during ischemiano effect on gastric mucosal blood flow during ischemia‐reperfusion. These results suggest that endogenous PAF may play an important role in gastric mucosal injury induced by ischemia‐reperfusion, and that CV‐6209 exerts its beneficial effect mainly by inhibiting neutrophil superoxide production induced by PAF.
Absolute configuration of 12‐Oxo‐10,15(Z)‐phytodienoic acid
Authors: Hamberg Mats , Miersch Otto , Sembdner Gunther
Published: November 2006

12‐Oxo‐10,15(Z)‐phytodienoic acid biosynthesized from 13(S)‐hydroperoxy‐9(Z),11(E),15(Z)‐octadecatrienoic acid using a preparation of corn (Zea mays L) hydroperoxide dehydrase recently was found to be a mixture of enantiomers in a ratio of 82∶18 (Hamberg, M., and Hughes, M.A. (1988)Lipids 23, 469–475). In this work, 12‐oxophytodienoic acid and (+)‐7‐iso‐jasmonic acid were converted into a common derivative, methyl 3‐hydroxy‐2‐pentyl‐cyclopentane‐1‐octanoate. From gas liquid chromatographic analysis of the (−)‐menthoxycarbonyl derivative of methyl 3‐hydroxy‐2‐pentyl‐cyclopentane‐1‐octanoates prepared from 12‐oxophytodienoic acid and (+)‐7‐iso‐jasmonic acid, it could be deduced that the major enantiomer of 12‐oxophytodienoic acid had the 9(S),13(S) configuration. Therefore, in the major enantiomer of 12‐oxophytodienoic acid, the configurations of the side chainbearing carbons are identical to the configurations of the corresponding carbons of (+)‐7‐iso‐jasmonic acid, thus giving support to previous studies indicating that 12‐oxophytodienoic acid serves as the precursor of (+)‐7‐iso‐jasmonic acid in plant tissue.
Geraniol interferes with membrane functions in strains ofCandida andSaccharomyces
Authors: Bard Martin , Albrecht Mark R. , Gupta Navyash , Guynn Cynthia J. , Stillwell William
Published: November 2006

Geraniol, an olefinic terpene, was found to inhibit growth ofCandida albicans andSaccharomyces cerevisiae strains. Geraniol was shown to enhance the rate of potassium leakage out of whole cells and also was shown by fluorescence polarization to increaseC. albicans membrane fluidity. Biophysical studies using differential scanning calorimetry, fluorescence polarization and osmotic swelling of phospholipid vesicles demonstrated that geraniol decreased the phase‐transition temperature of dipalmitoylphosphatidylcholine vesicles, affected fluidity throughout the bilayer, particularly the central portion of the bilayers, and caused an increase in bilayer permeability to erythritol. Geraniol may have potential use as an antifungal agent.
Polyunsaturated fatty acids of serum lipids in myocardial infarction
Authors: Croffs John W. , Ogburn Paul L. , Johnson Susan B. , Holman Ralph T.
Published: November 2006

Two groups of volunteers had blood drawn for serum analysis of fatty acids. The first group was comprised of patients admitted to the hospital with possible myocardial infarction (MI). Blood was drawn at admission and at 12, 24 and 48 hr. These patients were subsequently divided into three groups, those with MI, those without (No MI) and those taking prostaglandin inhibitors (PGI), on the basis of the cardiac enzymes, electrocardiograms and clinical history. A fourth group of Normal nonstressed people was also drawn at 0, 12, 24 and 48 hr for comparison. Fatty acid composition of phospholipids (PL), nonesterified fatty acids (NEFA), triglycerides (TG) and cholesteryl esters (CE) was determined by capillary gas chromatography (GC), and comparison were made between the MI, No MI, PGI and Normal groups. Total NEFA were significantly elevated in patients admitted for possible MI compared with Normals. Those patients with MI had marginally higher levels of NEFA than the No MI group at each sampling time, but this difference was not statistically significant. The MI, No MI and PGI groups had significantly different fatty acid patterns in NEFA with reduced percentages of arachidonic acid (AA) than controls. The fatty acid patterns in the four lipid classes showed few significant differences comparing the MI, No MI and PGI groups. The regular use of prostaglandin inhibitors before hospitalization for chest pain was associated with a reduced frequency of MI (p<0.002). NEFA levels, nonesterified AA levels and fatty acid patterns in this group did not differ from those patients not taking prostaglandin inhibitors.
Microsomal desaturation‐elongation of linoleic acid following parenteral feeding with lipid emulsions in the rat
Authors: Innis Sheila M. , Yuen Doris E.
Published: November 2006

The effect of total parenteral nutrition (TPN) with lipid emulsion to supply either 27.5% or 2% total calories on in vitro desaturation‐elongation of 18∶2(n−6) by liver microsomes was studied in the rat. The emulsion lipid contained ca. 50% 18∶2(n−6) plus 8% 18∶3(n−3) or 77% 18∶2(n−6) plus 0.5% 18∶3(n−3). The reaction rate was influenced by the in vitro substrate concentration and inhibited above 50 μmol 18∶2(n−6)/mg microsomal protein. At maximum rates of desaturation‐elongation, the formation of triene and tetraene (n−6) fatty acids was reduced in rats given either of the two emulsions. The rate of (n−6) pentaene formation was increased in rats given the emulsion with low 18∶3(n−3) but not in rats given the emulsion with 8% 18∶3(n−3). Analyses of the microsomal lipid indicated increased free cholesterol in all rats that received TPN. Esterified cholesterol was increased only in rats given 27.5% TPN calories as lipid. Microsomal total phospholipids and phospholipid class distributions were not altered by TPN. The data are consistent with reports of reduced levels of long‐chain desaturation‐elongation metabolites of 18∶2(n−6) in tissue phospholipids following infusion of parenteral lipid. The data suggest that the mechanism may include alterations in other metabolic pathways such as cholesterol, in addition to desaturase enzyme activities, and may be influenced by both the quantity and fatty acid composition of the lipid infused.
Fenton reactions in lipid phases
Authors: Schaich K. M. , Borg D. C.
Published: November 2006

Metal catalysis of membrane lipid oxidation has been thought to occur only at cell surfaces. However, conflicting observations of the pro‐oxidant activity of ferric (Fe3+) vs ferrous (Fe2+) forms of various chelates have raised questions regarding this dogma. This paper suggests that the solubilities of iron complexes in lipid phases and the corresponding abilities to initiate lipid oxidation there, either directly or via Fenton‐like production of reactive hydroxyl radicals, are critical determinants of initial catalytic effectiveness.

Partitioning of Fe3+ and Fe2+ complexes and chelates into bulk phases of purified lipids was quantified by atomic absorption spectroscopy. mM solutions of iron salts partitioned into oleic acid at levels of about micromolar. Ethylenediamine tetraacetic acid (EDTA) and diethylenetriaminepentaacetic acid (DTPA) chelates were somewhat less soluble, while adenosine diphosphate (ADP) chelates, and ferrioxamine were soluble as chelates at greater than 10−5 M. Solubilities of all iron compounds in methyl linoleate were 10‐ to 100‐fold lower.

To determine whether Fenton‐like reactions occur in lipid phases, H2O2 and either Fe2+ or Fe3+ and a reducing agent were partitioned into the lipid along with the spintrap 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO), and free radical adducts were recorded by electron paramagnetic resonance (EPR). Hydroxyl radicals (OH.) adducts were observed in oleic acid, but in lipid esters secondary peroxyl radicals predominated, and the presence of OH. adducts was uncertain.
Ascorbate‐enhanced lipid peroxidation in photooxidized cell membranes: Cholesterol product analysis as a probe of reaction mechanism
Authors: Bachowski Gary J. , Thomas James P. , Girotti Albert W.
Published: November 2006

Cholesterol was used as an in situ probe for studying mechanisms of lipid peroxidation in isolated erythrocyte membranes subjected to different prooxidant conditions. The membranes were labeled with [14C]cholesterol by exchange with prelabeled unilamellar liposomes and photosensitized with hematoporphyrin derivative. Irradiation with a dose of blue light resulted in thiobarbituric acid‐detectable lipid peroxidation that was increased markedly by subsequent dark incubation with 0.5–1.0 mM ascorbate (AH−). Ascorbate‐stimulated lipid peroxidation was inhibited by EDTA, desferrioxamine (DOX) and butylated hydroxytoluene (BHT), suggesting that the process is free radical in nature and catalyzed by membrane‐bound iron. Thin layer chromatography and radiometric scanning of extracted lipids from photooxidized membranes revealed that the major oxidation product of cholesterol was the 5α‐hydroperoxide (5α‐OOH), a singlet oxygen adduct. Post‐irradiation treatment with AH−/Fe(III) resulted in an almost‐total disappearance of 5α‐OOH and the preponderance of free radical oxidation products, e.g. 7‐ketocholesterol, the epimeric 7α‐/7β‐hydroperoxides (7α‐/7β‐OOH) and their respective alcohols (7α‐/7β‐OH). EDTA, DOX and BHT inhibited the formation of these products, while catalase and superoxide dismutase had no effect. These results are consistent with a mechanism involving 1‐electron reduction of photogenerated hydroperoxides to oxyl radical, which trigger bursts of free radical lipid peroxidation. Though generated in this system, partially reduced oxygen species, viz. superoxide, hydrogen peroxide and hydroxyl radical, appear to be relatively unimportant in the autoxidation process.
Sunlight, melanogenesis and radicals in the skin
Authors: Chedekel Miles R. , Zeise Lisa
Published: November 2006

Melanocytes are cells of neural crest origin residing at the dermal‐epidermal juncture. They produce specialized organelles called melanosomes within which the biochemical processes of melanization occurs. UV radiation is capable of inducing melanogenesis and, during the biosynthesis of melanins, several of the putative precursors “leak out” of the melanosome and can be detected in the skin, serum and urine of individuals undergoing active melanogenesis. Most notable are the cysteinyldopas (formed by nucleophilic addition of cysteine to dopaquinone) and several dihydroxyindoles (formed by intramolecular cyclization of dopaquinone). These catechols often are methylated in the melanocyte to afford a mixture of the monomethoxy derivatives and, in some cases, the dimethoxy species.

Recent investigations in our laboratories have demonstrated that the cysteinyldopas, dihydroxyindoles, and their various methylated derivatives are photochemically unstable. Irradiation with biologically relevant ultraviolet radiation (i.e. wavelengths >300 nm) results in the rapid destruction of the precursors/metabolites and the production of a variety of free radical species. The photochemistry and potential photobiological significance of melanogenic intermediates is discussed.
Reactive oxygen in the tumor promotion stage of skin carcinogenesis
Authors: Fischer Susan M. , Cameron Gregory S. , Baldwin James K. , Jasheway Daniel W. , Patrick Kelly E.
Published: November 2006

Exposure of isolated SENCAR mouse epidermal cells to the tumor promoter 12‐0‐tetradecanoylphorbol‐13‐acetate (TPA) in vitro resulted in the production of oxidant species detected as chemiluminescence. This oxidant response can be inhibited by superoxide dismutase and copper complexes but not catalase or scavengers of hydroxyl radical or singlet oxygen, suggesting that the oxidant is superoxide anion. Inhibitors of various parts of the arachidonate cascade affect the TPA‐induced oxidant response in a manner that corresponds to their effects on in vivo tumor promotion experiments. Agents that inhibit lipoxygenase activity, i.e. nordihydroguaiaretic acid, benoxaprofen, but not agents that are cyclooxygenase inhibitors, i.e. indomethacin, are effective in suppressing the oxidant response to TPA. Phospholipase C but not phospholipase A2 or D produced an oxidant response kinetically similar to that elicited by TPA. The inhibitors of TPA‐induced oxidants inhibited the phospholipase C response to the same extent, suggsting that TPA and phospholipase C may produce an oxidant species through a common mechanism, via phospholipid turnover‐protein kinase C activation. The relevance of oxidant production to the tumor promotion process is suggested by the ability of exogenous xanthine/xanthine oxidase, a superoxide anion‐generating system, to induce ornithine decarboxylase, a characteristic of TPA‐treated cells. In addition, oxidant production is significantly lower in cells from the TPA‐promotion resistant C57BL/6J mouse. These studies provide further support for a role for reactive oxygens in the tumor promotion process.
Biopsy method for human adipose with vitamin E and lipid measurements
Authors: Handelman Garry J. , Epstein William L. , Machlin Lawrence J. , van Kuijk Frederik J. G. M. , Dratz Edward A.
Published: November 2006

An adaptation of the needle biopsy procedure of Beynen and Katan for human adipose tissue, which yields 2–10 mg adipose samples, is described and evaluated. Micromethods are presented for the analysis of α‐tocopherol, cholesterol and fatty acids in each adipose specimen. The needle biopsy procedure, which uses a Vacutainer to create suction, is compared with a punch biopsy method. The needle biopsy is rapid (6 samples/hr), simple and unobjectionable to the subjects, and provides samples with reproducible ratios of cholesterol and α‐tocopherol. Unlike the punch biopsy, the needle biopsy reliably obtains specimens with a lipid composition typical of adipocytes. The needle biopsy method is adaptable to nutritional studies of tocopherol and fatty acid metabolism in adipose, and to studies of hazardous compounds stored in adipose. The linoleic acid content of adipose from residents of the West Coast was found to be considerably higher than values reported earlier. The adipose fatty acid data indicate an increase in human adipose linoleate when compared with earlier reports and suggest a trend toward increasing linoleic acid in the American diet.
A simplified approach to the analysis of subclasses of phospholipids: Application to human platelets
Authors: Vishnubhatla Indira , Kates Morris , Adams George A.
Published: November 2006

A procedure for the determination of the proportions of diacyl, alkenylacyl and alkylacyl subclasses of glycerolphospholipids was developed. The procedure involves: (1) acid methanolysis of the phospholipid followed by Bligh/Dyer extraction of fatty acid methyl esters (FAME) derived from acyl chain types, dimethylacetals (DMA) derived from alkenyl ether chain types, and lysoalkyl phosphatidic acids (lysoalkyl‐PA) derived from alkyl ether chain types; and (2) subsequent acetolysis to convert the lysoalkyl‐PA to monoalkyl glycerol diacetates (MAGD). GLC analysis and quantitation (using internal standard, 21∶0 FAME) of FAME, DMA and MAGD allowed calculation of the proportions of the three molecular subclasses. The methanolysis/acetolysis procedure gave an overall mean phospholipid recovery of 95±3%. Analysis of the major phospholipids in four separate preparations of fresh resting human platelets by this procedure showed the following range of molecular subclasses: phosphatidylcholine (PC), 86–92 mol % diacyl, 6–10 mol % alkylacyl and 2–3 mol % diacyl, 5–8 mol % alkylacyl and 34–55 mol % alkenylacyl. The results of these subclass analyses were in general agreement with those reported in the literature.
Modification of the fatty acid composition of L1210 leukemia subcellular organelles
Authors: Burns C. Patrick , North James A. , Mossman Craig J. , Ingraham Leah M.
Published: November 2006

We have examined the extent to which it is possible to modify the fatty acid composition of subcellular organelles of L1210 leukemia cells. A polyunsaturated fatty acid, docosahexaenoic acid, or a monounsaturated fatty acid, oleic acid, were added to the culture media. After 48 hr, the cells were ruptured and the subcellular fractions isolated. Fatty acid analysis revealed that nuclei, mitochondria, plasma membranes and microsomes of the cells grown in media supplemented with docosahexaenoic acid contained increased amounts of polyenoic fatty acids, mean number of double bonds and docosahexaenoic acid compared with cells grown in oleic acid. We conclude that it is possible to experimentally modify the lipids of multiple intracellular structures of L1210 cells by the addition of fatty acids to the growth media.
Identification of N‐ε‐(2‐propenal)lysine as a major urinary metabolite of malondialdehyde
Authors: Draper H. H. , Hadley M. , Lissemore L. , Laing N. M. , Cole P. D.
Published: November 2006

N‐ε‐(2‐propenal)lysine (ε‐PL) was identified as one of two major metabolites of malondialdehyde (MDA) excreted in rat and human urine. This compound is derived mainly but not exclusively from the diet, where it arises from a reaction between free MDA generated in the oxidative decomposition of polyunsaturated fatty acids and the ε‐amino of the lysine residues of food proteins. It is released during protein digestion and represents the main form in which MDA is absorbed. It is excreted partially in unchanged form and partially as the acetylated derivative N‐α‐acetyl‐N‐ε‐(2‐propenal)lysine. Its administration to rats did not result in an increase in the excretion of free MDA in the urine. The findings that MDA in foods is absorbed mainly as ε‐PL, and that this compound is not metabolized to free MDA in vivo, mitigate concern over the possible mutagenicity and carcinogenicity of MDA in the diet.
Lipoprotein(a): Nonhuman primate models
Authors: Makino Kazuhiko , Scanu Angelo M.
Published: November 2006

Lipoprotein(a) [Lp(a)] is a low density lipoprotein which has apo(a) disulfide‐linked to apoB100. Apo(a) has recently been shown to have a striking homology with plasminogen, a knowledge that has stimulated a lot of interest in the mechanism of atherogenicity and thrombogenicity of this lipoprotein particle. Several studies have documented the presence of Lp(a) in nonhuman primates with particular reference to the rhesus monkeys and baboons. The Lp(a) of rhesus monkey is structurally very similar to that of humans, except for the absence of kringle V and the amino acid composition of the catalytic region. The Lp(a) of nonhuman primates, like their human counterparts, exhibit a wide range of interindividual plasma levels and also a wide size polymorphism of apo(a). Nonhuman primates appear to represent a good model for the study of the structure and biology of Lp(a).
ApoA‐I secretion by rabbit intestinal mucosa cell cultures
Authors: Carlson Ting L. , Kottke Bruce A.
Published: November 2006

Lipid and apolipoprotein (apo) A‐I concentrations in different density fractions of New Zealand White (NZW) and Watanabe (WHHL) rabbit plasma were studied. Aside from the low plasma apoA‐I and high density lipoprotein (HDL) cholesterol levels in WHHL rabbits, the distribution of apoA‐I was also different between the two rabbits. ApoA‐I was concentrated in both the HDL2 and HDL3 fractions of NZW rabbits but was found primarily in the HDL3 fraction of WHHL rabbits. ApoA‐I secretion in these two rabbits was further studiedin vitro by using intestinal and hepatocyte cell cultures. ApoA‐I secretion was highest from cultures of the duodenum and the proximal end of the jejunum; whereas, cell cultures of the distal end of the small intestine secreted very little apoA‐I into the medium. Intestinal cell cultures from WHHL rabbits secreted less, but significant amounts of, apoA‐I compared to that of NZW rabbits. ApoA‐I was most concentrated in the density range of 1.12–1.21 (HDL3) fraction in medium containing 10% fetal calf serum (FCS). Serum‐free medium promoted apoA‐I secretion by intestinal cell cultures that was mostly found in the d>1.21 (lipoprotein‐deficient) fraction. Hepatocytes isolated from the same rabbits by collagenase perfusion secreted little apoA‐I, and it was found only in the d>1.21 fraction. The addition of oleic acid into the culture medium with 10% FCS decreased the secretion of total apoA‐I and HDL by intestinal cell cultures and increased the secretion of very low density lipoprotein (VLDL) and intermediate density lipoproteins (IDL). The results indicate that intestinal cells, not hepatocytes, are responsible for the secretion of apoA‐I and HDL3 in rabbits, and that the secretion may be regulated under different nutritional conditions.
Characterization of the coronary vascular responses to platelet‐activating factor in the isolated perfused heart
Authors: Hu Weimin , Choy Patrick C. , Man Ricky Y. K.
Published: November 2006

Platelet‐activating factor (PAF) is a potent phospholipid mediator with diversein vivo andin vitro coronary vascular effects. In the present study, the coronary vascular responses to bolus injections of PAF were compared in rat hearts perfused under constant flow and under constant pressure. Low levels of PAF (1 pmol) produced vasodilatation only, while higher PAF concentrations (100 pmol) produced initial vasodilatation which was followed by a vasoconstriction under both experimental conditions. To determine species differences in PAF action, the effect of PAF was tested on perfused guinea pig hearts. Unlike in perfused rat hearts, only a dosedependent vasoconstrictor response was observed in perfused guinea pig hearts following a bolus injection of 1 fmol to 10 pmol of PAF. The results from repeated injections of PAf indicated that depletion of vasoactive mediators induced by PAF or receptor desensitization may explain a failure of a second injection of PAF to initiate a vasoconstrictor response. After PAF injection, the coronary vascular response to leukotriene was not altered, indicating that the reduced vasoconstrictor effect of a second injection of PAF cannot be due to a reduced ability of the smooth muscle to constrict. The study demon‐strates that similar coronary vascular responses to PAF are observed in perfused rat hearts under either constant flow rate or constant pressure and that some of the variable coronary vascular responses reported may be due to the difference between animal species.
Dietary fat composition influences fatty acid composition of milk fat globule membrane in lactating cows
Authors: Palmquist D. L. , Schanbacher F. L.
Published: November 2006

Milk fat globule membranes are derived directly from the apical plasma membrane of mammary epithelial cells. To evaluate the effect of dietary fat on mammary membranes, we determined the fatty acid composition of the milk fat globule membrane in lactating dairy cows fed diets supplemented with fats of different fatty acid composition, or infused intravenously with soy oil emulsion. A preliminary survey, using an abbreviated preparation procedure (membranes isolated at 48,000×g‐max for 15 min), yielded about 45% of the total membrane fatty acids that could be recovered by centrifuging at the same speed for 120 min, and showed that changes in fatty acid composition of membranes reflected dietary fatty acids to some extent. Dietary palmitic acid increased the content of 16∶0 in the membranes. A high corn diet increased ruminal formation oft18∶1, and its level increased to 12% of membrane fatty acids. Infusion of soy oil emulsion increased 18∶2 membrane content, and decreased the levels of 18∶1 and 20∶4. All treatments decreased the ratio of unsaturated/saturated fatty acids as compared to controls, whereas the ratio of polyunsaturated/saturated fatty acids was increased by feeding a high corn diet or by infusing soy oil. The ratio of 18∶2/c18∶1 increased from 0.31 to 1.0 after infusing soy oil for 4 days. The fatty acids of membranes isolated upon 120‐min centrifugation were slightly more saturated. The differences were not sufficiently large, however, to affect overall results significantly.
Tocopherol contents of lipoproteins from frozen plasma separated by affinity chromatography
Authors: Clevidence Beverly A. , Ballard‐Barbash Rachel
Published: November 2006

We investigated whether freezing and storage of plasma altered α‐tocopherol levels of whole plasma or the lipoprotein fractions derived from such plasma. Plasma from 24 men, at each of two collection periods, was frozen at −20°C for six weeks, then high‐density lipoproteins (HDL) were separated from low‐ plus very low‐density lipoproteins (LDL‐VLDL) by heparin affinity chromatography. Whole plasma and the lipoprotein fractions were analyzed for α‐tocopherol content and compared to counterparts from fresh plasma. Freezing and storage did not reduce α‐tocopherol levels of plasma or the lipoprotein fractions. α‐Tocopherol values from fresh and frozen plasma were highly correlated for both plasma (period 1, r=0.94; period 2, r=0.93) and the LDL‐VLDL fractions (periods 1 and 2, r=0.97). Percent distribution of α‐tocopherol between the two lipoprotein fractions was comparable for lipoproteins derived from fresh and frozen plasma. Under the storage conditions used in this study, plasma can be frozen for at least six weeks prior to lipoprotein fractionation with no detectable detrimental effects on α‐tocopherol content of either plasma or lipoproteins.
Metabolism of meadowfoam oil fatty acids in mice
Authors: Emken E. A. , Adlof R. O. , Abraham S.
Published: November 2006

Meadowfoam oil is unusual because over 95% of the fatty acids are 20‐ and 22‐carbon aliphatic acids withcisdouble bonds located principally at the 5‐ and/or 13‐position. Since little information is available on the metabolism of the 5c−20∶1 and 5c,13c−22∶2 fatty acids, an exploratory study in mice was conducted to investigate the metabolism of purified samples of the free fatty acids isolated from meadowfoam oil, and to determine the effect of meadowfoam oil on weight gain and tissue lipid composition. Mice fed diets containing 5% by wt of the purified 5c−20∶1 or 5c,13c−22∶2 for 6 days exhibited no apparent physiological problems. Total liver lipids from mice fed the purified fatty acid diets contained mean values of 2.0% 5c−20∶1 and 2.1% 5c,13c−22∶2; total heart lipids contained 1.7% 5c−20∶1 and 10.7% 5c,13c−22∶2. Liver total phospholipids from mice fed a 5% meadowfoam oil diet for 19 wk contained 1.4% 5c−20∶1 and 1.9% 5c,13c−22∶2. There was no evidence of desaturation, elongation or retroconversion. Weight gain for mice fed the meadowfoam oil diet for 19 wk was similar to mice fed corn oil, and was higher than for mice fed hydrogenated cottonseed oil. Considering the high 5c−20∶1 and 5c,13c−22∶2 content of the diets, the percentages of these fatty acids in mouse tissue lipids from both the short‐ and long‐term studies were low. Weight gain was surprisingly good since the meadowfoam oil diet was essential fatty acid‐deficient. Results of this initial investigation suggest that the 5c−20∶1 and 5c,13c−22∶2 fatty acids were utilized primarily for energy. In the short‐term study, these fatty acids did not produce toxic effects or cause metabolic problems.
Prostaglandin synthesis and fatty acid composition of phospholipids and triglycerides in skeletal muscle of chicks fed combinations of flaxseed oil and animal tallow
Authors: Olomu J. M. , Baracos V. E.
Published: November 2006

Chicks were fed isocaloric and isonitrogenous diets containing 6% (w/w) added fat consisting of various proportions of animal tallow and flaxseed oil (FSO). No differences among treatments were seen in growth rate, muscular deposition of protein and lipids nor in the muscle phospholipid (PL) and triglyceride (TG) contents. Prostaglandin (PG)E2 synthesis in isolated skeletal muscle was depressed significantly by feeding FSO or by treatment with naproxen (6‐methoxy‐α‐methyl‐2‐napthaleneacetic acid), an inhibitor of PG synthesis. The changes associated with diet may be related to differences in the fatty acid composition of muscle lipids. Levels of saturated fatty acids in muscle PL and TG were relatively insensitive to dietary treatments. Monounsaturated fatty acid levels were significantly lower in the FSO‐fed groups. FSO diets caused significant depression in muscle PL 20∶4ω6 and almost completely inhibited 22∶5ω6 incorporation. FSO diets decreased ratios of ω6/ω3 fatty acids and increased the unsaturation index of muscle PL. Muscles of chicks fed FSO showed increased levels of 18∶3ω3, and of its derivatives 20∶4ω3 and 22∶5ω3. These results suggest that FSO inhibits PG synthesis and modifies the fatty acids of PL and TG of chick muscle. These changes may have implications for PG‐dependent and/or membrane‐dependent processes in muscle metabolism.
High‐performance liquid chromatographic separation of enantiomeric alkyl glycerol ethers
Authors: Foglia Thomas A. , Maeda Kazuhito
Published: November 2006

The resolution of a series of racemic 1‐alkyl‐3‐trityl‐rac‐glycerols and 1‐alkyl‐2‐benzyl‐rac‐glycerols into their enantiomers by high‐performance liquid chromatography (HPLC) was investigated. Of the racemic glycerol derivatives studied, only three (1,2‐0‐isopropylidene‐rac‐glycerol, 1,2‐0‐isopropylidene‐3‐benzyl‐rac‐glycerol and 1‐hexadecyl‐2‐benzyl‐rac‐glycerol) could be resolved into their enantiomers. The compounds were resolved on a silica (10 μm) column coated with cellulose tribenzoate and eluted isocratically with hexane/isopropanol as mobile phase. The effects of mobile phase composition, column temperature and flow rate on the resolution of enantiomeric pairs were investigated. Also, the effect of substituents,i.e., trityl, benzyl, hydroxyl or alkyl, on the resolution of the alkyl glycerol ethers by HPLC was evaluated.
A high cholesterol/cholate diet induced fatty liver in spontaneously hypertensive rats
Authors: Ueno Kohji , Okuyama Harumi
Published: November 2006

A high cholesterol diet was found to induce fatty liver in spontaneously hypertensive rats. Although cholesterol ester and triacylglycerol accumulated in large amounts in liver, the increases of these lipids in plasma were relatively small and no increase in cholesterol and cholesterol ester was observed in aorta. In rats fed normal diet, plasma cholesterol ester mainly consisted of arachidonate species; however, oleate and linoleate esters became the most prominent species in rats fed a high‐cholesterol diet. The amounts of oleate and linoleat at the 2‐position of phosphatidylcholine in both plasma and liver were increased slightly, but the fatty acids of aorta lipids changed little by feeding a high cholesterol diet. These results indicate that the livers of rats fed the high cholesterol diet do not secrete cholesterol ester and triacylglycerol with altered fatty acids as rapidly as they are synthesized and that the increased levels of cholesterol oleate in liver and plasma are not directly correlated with atherogenic lesions under these conditions.
Substrate specificity of lysosomal cholesteryl ester hydrolase isolated from rat liver
Authors: Klemets Rabbe , Lundberg Bo
Published: November 2006

The effect of various physicochemical forms of substrate on the activity of acid cholesteryl ester hydrolase isolated from rat liver lysosomes was studied. The amount of sodium taurocholate was varied in the substrate mixture which contained constant amounts of egg phosphatidylcholine (PC) and cholesteryl oleate. The resulting substrate forms produced were PC vesicles, PC vesicles with incorporated sodium taurocholate, mixed micelles, and mixed micelles together with free bile salt micelles. Gradually increasing amounts of sodium taurocholate activated cholesteryl oleate hydrolysis until the molar sodium taurocholate/PC ratio of ca. 0.6; thereafter hydrolytic activity decreased rapidly. The presence of sodium taurocholate micelles clearly inhibits cholesteryl oleate hydrolysis. We therefore propose that the activation observed at low bile salt concentrations depends on bile salt interaction with the substrate vehicle, whereas the inhibition observed at high bile salt concentrations depends on sodium taurocholate interacting with the enzyme. When comparing different phospholipid components in the supersubstrate, the enzyme activity was highest in the presence of dioleyl PC and decreased when present with dipalmitoyl PC and egg PC. Egg lysoPC completely inhibited the enzyme activity. A net negative charge on the surface of the vesicle substrate increased cholesteryl ester hydrolase activity while a net positive charge on the surface inhibited the enzyme activity. Only part of the product inhibition of cholesteryl oleate hydrolase caused by Na‐oleate was reversible when tested with bovine serum albumin present in the incubation mixture.
(24S)‐14α,24‐dimethyl‐9β,19‐cyclo‐5α‐cholest‐25‐en‐3β‐ol: A new sterol and other sterols inMusa sapientum
Authors: Akihisa Toshihiro , Shimizu Naoto , Tamura Toshitake , Matsumoto Taro
Published: November 2006

The structure of a new sterol isolated fromMusa sapientum has been shown by chemical and spectroscopic methods to be (24S)‐14α,24‐dimethyl‐9α,19‐cyclo‐5α‐cholest‐25‐en‐3β‐ol. In addition, several known (24S)‐24‐methyl‐Δ25‐sterols, their 24‐methylene isomers and other sterols (4,4‐dimethyl‐, 4α‐methyl‐ and 4‐demethyl‐sterols) together with 3‐oxo‐4α‐methylsteroids were isolated from the plant and identified. The biogenetic implication of these sterols and 3‐oxosteroids is discussed.
Reversibility of cholinephosphotransferase in lung microsomes
Authors: Tsao Francis H. C.
Published: November 2006

The effect of cytidine 5′‐monophosphate (CMP) on the incorporation of cytidine 5′‐diphosphate (CDP) [methyl‐14C]choline or [1‐14C]dipalmitoylglycerol into phosphatidylcholine (PC) catalyzed by rabbit lung microsomal CDP choline:1,2‐diacyl‐sn‐glycerol cholinephosphotransferase (EC 2.7.8.2) was studied. In the presence of 0.85 mM CMP and nonsaturating diacylglycerol concentration, the incorporation of CDP[14C]choline into PC was markedly stimulated, but the incorporation of [14C]dipalmitoylglycerol into PC was inhibited. This was due to the increase of endogenous diacylglycerol generated from microsomal PC by the cholinephosphotransferase reverse reaction. However, the newly synthesized PC was not readily hydrolyzed in the presence of CMP. The results of this study suggest that the endogenous membranous diacylglycerol is utilized more preferentially for PC synthesis than the exogenous diacylglycerol and that the newly synthesized PC could rapidly equilibrate with the endogenous membrane PC pool.
Evidence that cholesteryl ester hydrolase and triglyceride lipase are different enzymes in rat liver
Authors: Chen James J. S. , Rothman Vicki , Margolis Simeon
Published: November 2006

Studies on intracellular cholesteryl ester hydrolase (CEH) and triglyceride lipase (TGL) from rat adipose tissue and adrenal cortex have suggested that a single protein is responsible for both activities. To determine whether one hepatic protein catalyzes both reactions, we studied several properties of CEH and TGL in rat liver. During liver perfusion with heparin, perfusate peaks of TGL and CEH did not consistently coincide, and TGL activity was considerably higher and less heat‐stable than that of CEH. Significant TGL, but not CEH, activity was released during incubation of isolated hepatocytes. Although microsomes isolated from hepatocytes contained both activities, the specific activities of CEH and TGL in cytosol from hepatocytes were 95% and 3%, respectively, of those found in cytosol from whole liver. Preincubation of liver cytosol with 5 mM Mg2+ decreased CEH, but not TGL, activity. Intracellular CEH and TGL activities were completely separated by prep‐disc gel electrophoresis. Finally, both cytosolic and microsomal TGL, but not CEH, activities were inhibited by antiserum against rat hepatic TGL. We conclude that extracellular TGL does not have CEH activity and intracellular CEH differs from TGL.
The effect of feeding fish oils, vegetable oils and clofibrate on the ketogenesis from long chain fatty acids in hepatocytes
Authors: Bergseth Steinar , Christiansen Erling N. , Bremer Jon
Published: November 2006

Groups of rats were fed diets containing 25% fish oil (FO), 25% soybean oil, 25% partially hydrogenated fish oil (PHFO), 25% partially hydrogenated soybean oil (PHSO), 25% partially hydrogenated coconut oil or 0.3% clofibrate for 3 wk. After the animals were fasted for 24 hr, hepatocytes were isolated and ketogenesis from added palmitate, linoleatecis andtrans, arachidonate and docosahexaenoate was measured. Ketogenesis after oil feeding was significantly stimulated (two‐to threefold) only in cells from the PHFO‐and PHSO‐fed rats. The stimulation was most apparent with the long chain unsaturated fatty acids as substrates. These fatty acids were relatively poor ketone body precursors in control hepatocytes. Essential fatty acid deficiency did not seem to be the reason for this stimulation. Clofibrate also stimulated ketogenesis significantly (1.5‐ to 3‐fold). The degree of stimulation increased with chain length and degree of unsaturation of the substrate. The activity of the enzyme 2,4‐dienoyl‐CoA reductase was also studied in the same groups. Its activity was stimulated about fourfold in the clofibrate‐treated rats and to a lesser extent by the PHFO, PHSO and FO diets. The activity showed no correlation with the content of unsaturated fatty acids in the diet or their oxidation in isolated hepatocytes. The 2,4‐dienoyl‐CoA reductase, therefore, does not seem to be a regulatory enzyme in the metabolism of dietary polyunsaturated fatty acids. It is concluded that an induction of the peroxisomal β‐oxidation system most likely is involved in the reported increases in ketogenesis from very long chain polyunsaturated fatty acids.
Structures of three new 24,24‐dimethyl‐Δ7‐sterols fromGynostemma pentaphyllumfromGynostemma pentaphyllum
Authors: Akihisa Toshihiro , Shimizu Naoto , Tamura Toshitake , Matsumoto Taro
Published: November 2006

The structures of three new sterols isolated fromGynostemma pentaphyllum (Cucurbitaceae) have been shown by chemical and spectroscopic methods to be 24,24‐dimethyl‐5α‐cholest‐7‐en‐3β‐ol, (22E)‐24,24‐dimethyl‐5α‐cholesta‐7,22‐dien‐3β‐ol and 24,24‐dimethyl‐5α‐cholesta‐7,25‐dien‐3β‐ol.
Cyclic AMP increases incorporation of exogenous fatty acids into triacylglycerols in hamster fibroblasts
Authors: Mazière Cécile , Mazière Jean‐Claude , Mora Liliana , Auclair Martine , Polonovski Jacques
Published: November 2006

Incorporation of various exogenous saturated or unsaturated [14C]labeled fatty acids (palmitic, stearic, oleic, linoleic and arachidonic) into triacylglycerols by hamster fibroblasts was markedly enhanced (two‐to fourfold) in the presence of theophylline or dibutyryl cyclic adenosinemonophosphate (dbcAMP). This effect was observed for short‐term (1–6 hr) as well as long‐term (15–24 hr) preincubation with dbcAMP. In the presence of sodium fluoride, a phosphoprotein phosphatase inhibitor, measurement of diacylglycerol acyltransferase (DGAT) activity in cells pretreated with dbcAMP pointed out a marked increase (3X) in specific activity. The results suggest that DGAT activity in fibroblasts could be activated by a cAMP‐dependent phosphorylation process.
Differences in the long chain (sphingoid) base composition of sphingomyelin from rats bearing Morris hepatoma 7777
Authors: Merrill Alfred H. , Wang Elaine , Wertz Philip W.
Published: November 2006

The long chain bases of sphingomyelin from Morris hepatoma 7777 and host and control livers were analyzed by capillary gas liquid chromatography. Sphingosine (18∶1) was the major long chain base of control livers (66.5%) and hepatomas (65.6%), but hepatomas also had a high percentage (9.3 vs 4.4) of the 16∶1 homolog. Host liver had the most unusual long chain base composition, with ca. equal 16∶1 (24.4%) and 18∶1 (21.4%) and high amounts of 20‐carbon bases (9.2% 20∶0 and 15.3% 20∶1). These differences may be related to the aberrant fatty acid metabolism known to occur in tumor‐bearing animals. Such large perturbations in the long chain base composition of hepatic sphingomyelin are unprecedented and could have a major impact on the properties of host membranes.
Absorption and transport of fat in mammals with emphasis on n−3 polyunsaturated fatty acids
Authors: Nelson Gary J. , Ackman Robert G.
Published: November 2006

The current state of knowledge concerning the absorption and transport of dietary fat with emphasis on long‐chain polyunsaturated n−3 fatty acids in mammals is reviewed. It is apparent that long‐chain polyunsaturated n−3 fatty acids, either as free acids or as part of triglycerides, are readily absorbed in the gut and transported by the circulatory system. Indeed, it would appear that long‐chain polyunsaturated n−3 fatty acids are digested, absorbed and transported similarly to other long‐chain fatty acids with only minor variations, although there is much that is still not understood about these processes. The main unresolved issues in the area of the absorption and transport of long‐chain polyunsaturated n−3 fatty acids appear to be: 1) If they, when located in the 2‐position of triglycerides, have unique metabolic pathways; and 2) whether the unnatural forms, i.e., methyl or ethyl ester derivatives, are suitable vehicles for administration as dietary supplements. The effect in man of dietary, long‐chain polyunsaturated n−3 fatty acids on blood serum lipid and lipoprotein levels, particularly the low density lipoproteins, remains controversial, except for the well‐documented reduction in serum triglyceride levels. Also, there is uncertainty regarding their distribution and metabolism in tissues. Finally, if the consumption of long‐chain polyunsaturated n−3 fatty acids has beneficial health consequences, what is the appropriate therapeutic dose? In view of these important, unresolved issues and uncertainties, it would seem prudent to direct additional research toward a better understanding of the overall process by which fat is digested, absorbed and transported.
Formation of red pigment by a two‐step 2‐thiobarbituric acid reaction of alka‐2,4‐dienals. Potential products of lipid oxidation
Authors: Kosugi Hiroko , Kato Tetsuta , Kikugawa Kiyomi
Published: November 2006

Reaction of 2,4‐hexadienal, 2,4‐nonadienal and 2,4‐decadienal with 2‐thiobarbituric acid (TBA) in aqueous acetic acid produced a 532‐nm absorbing red pigment. While the 1∶1 reaction of the aldehyde and TBA produced little pigment, reaction of the aldehyde with an excess amount of TBA produced significant amounts. Instant heating of the reaction mixture did not produce the pigment. However, initial reaction at 5°C and subsequent heating to 100°C produced the pigment efficiently (two‐step reaction). Pigment formation required water and dissolved oxygen. The yield of the pigment from the alka‐2,4‐dienals was 1/10–1/20 of that from malonaldehyde. In the first step of the reaction at 5°C, the 1∶1 adducts of the aldehydes at the5‐position of TBA and several other uniden‐tified adducts were formed. In the second step, these adducts were converted at 100°C, in the presence of water and oxygen, into the red pigment. The structure of the red pigment from 2,4‐hexadienal was elucidated to be the 1∶2 adduct of malonaldehyde and TBA. 2‐Hexenal andt‐butylhydroperoxide showed marked synergistic effects on the pigment formation from the alka‐2,4‐dienals. Red pigment formation due to the alka‐2,4‐dienals may be enhanced by the presence of other aldehydes and hydro‐peroxides.
Localization of long‐chain fatty acids and unconventional sterols in spherulous cells of a marine sponge
Authors: Lawson Mishelle P. , Thompson Janice E. , Djerassi Carl
Published: November 2006

The first direct evidence is provided for the presence of unconventional lipids in a particular subcellular membrane system of a sponge. Spherulous cells were isolated from the variety of cell types present in the marine spongeAplysina fistularis by density gradient centrifugation. Spherulous cell plasma membrane was subsequently isolated by cell rupture followed by differential centrifugation and sucrose, or Percoll, density gradient ultracentrifugation. Plasma membrane isolates were identified and assessed for purity using [3H] concanavalin A plasma membrane marker, sodium dodecyl sulfate polyacrylamide gel electrophoresis and ratios of protein, sterol and phosphate. Plasma membrane isolates could not be assessed for purity by traditional enzymatic means. Spherulous cell plasma membrane was found to contain unusual lipids, including long‐chain (C24–C30) fatty acids (16.8–27.2%) and unconventional 26‐alkylated sterols (66.4–72.6%), in addition to more conventional fatty acids and sterols. Spherulous cell intracellular membranes were also found to contain long‐chain fatty acids and unconventional sterols, although the relative importance of these unusual lipids apparently varies between intracellular membranes, with some containing approximately 50% long‐chain acids.