bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification of plasmalogens usingRhizopus delemar lipase andNaja naja naja phospholipase A2
Authors: Hirashima Yutaka , Farooqui Akhlaq A. , Murphy Eric J. , Horrocks Lloyd A. 
Published: February 2007

AbstractBovine heart ChoGpl (choline glycerophospholipid) and bovine brain EtnGpl (ethanolamine glycerophospholipid) contain diacyl, alkenylacyl and alkylacyl analogs. Purification of plasmalogens was achieved usingR. delemar lipase andN. naja naja phospholipase A2 digestion. TheR. delemar lipase hydrolyzes the acyl bond at the 1‐position of 1,2‐diacyl glycerophospholipids. TheN. naja naja phospholipase A2 has greater activity with diacyl and alkylacyl than with alkenylacyl glycerophospholipids. These enzymes were mainly used to remove diacyl and alkylacyl analogs respectively. When the diacyl types were removed by double incubation withR. delemar lipase, the plasmalogen content was 94.2%±0.21% (mean±S.E.M., n=4) for PlsCho (plasmenylcholine) and 94.9%±0.19% (mean±S.E.M., n=3) for PlsEtn (plasmenylethanolamine). Recoveries were 74% and 88% respectively. These partially purified plasmalogens were treated withN. naja naja phospholipase A2. Finally, 97.7%±0.24% (mean±S.E.M., n=4) and 98.8%±0.27% (mean±S.E.M., n=3) pure plasmalogens were obtained for PlsCho and PlsEtn respectively. Plasmalogens were recovered in an overall yield of 7.7%±0.7% (mean±S.E.M., n=4) and 10.2%±1.2% (mean±S.E.M., n=3) for PlsCho and PlsEtn.
Metabolism of phosphatidylinositol in plasma membranes and synaptosomes of rat cerebral cortex: A comparison between endogenous Vs exogenous substrate pools
Authors: Navidi Meena , MacQuarrie Ronald A. , Sun Grace Y. 
Published: February 2007

AbstractThe metabolism of phosphatidylinositols (PI) labeled with [14C]arachidonic acid within plasma membranes or synaptosomes was compared to the metabolism of PI prelabeled with [14C]arachidonic acid and added exogenously to the same membranes. Incubation of membranes containing the endogenously‐labeled PI pool in the presence of Ca2+ resulted in the release of labeled arachidonic acid, as well as a small amount of labeled diacylglycerol. Labeled arachidonic acid was effectively reutilized and returned to the membrane phospholipids in the presence of adenosine triphosphate (ATP), CoA, and lysoPI. Although Ca2+ promoted the release of labeled diacylglycerol from prelabeled plasma membranes, this amount was only 17% of the maximal release, i.e., release in the presence of deoxycholate and Ca2+. This latter condition is known to fully activate the PI‐phospholipase C, and incubation of prelabeled plasma membranes resulted in a six‐fold increase in labeled diacylglycerols. On the other hand, when exogenously labeled PI were incubated with plasma membranes in the presence of Ca2+, the labeled diacylglycerols released were 59% of that compared to the fully activated condition. The phospholipase C action was calcium‐dependent, regardless of whether exogenous or endogenous substrates were used in the incubation. In contrast to plasma membranes, intact synaptosomes had limited ability to metabolize exogenous PI even in the presence of Ca2+, although the activity of phospholipase C was similar to that in the plasma membranes when assayed in the presence of deoxycholate and Ca2+. These results suggest that discrete pools of PI are present in plasma membranes, and that the pool associated with the acyltransferase is apparently not readily accessible to hydrolysis by phospholipase C.
Analysis of north atlantic and baltic fish oil triacylglycerols by high‐performance liquid chromatography with a silver ion column
Authors: Laakso Paivi , Christie William W. , Pettersen Jan 
Published: February 2007

AbstractTriacylglycerols from Atlantic herring (Clupea harengus), sandeel (Ammodytes sp.) and Baltic herring (Clupea harengus membras) have been fractionated by silver ion high‐performance liquid chromatography. An ion exchange column loaded with silver ions was the stationary phase, and a gradient in the mobile phase from 1,2‐dichloroethane/dichloromethane (1∶1, v/v) to acetone and then to acetone/acetonitrile (2∶1, v/v) was used to effect the separation with light‐scattering (i.e., mass) detection. Fractions were collected via a streamsplitter, and fatty acid methyl esters were prepared by transesterification in the presence of an internal standard for identification and quantification by gas liquid chromatography. Triacylglycerols were separated according to the number of double bonds in the fatty acyl residues. Resolution was excellent at first, when the least unsaturated molecules eluted (trisaturated to dimonoene‐monodiene fractions). Base‐line resolution could no longer be achieved when molecules containing trienoic or more highly‐unsaturated fatty acids began to elute because of overlapping components. Nonetheless, some valuable separations of species containing two saturated and/or monoenoic fatty acids and one polyenoic fatty acid were achieved. Double bond indices (average number of double bonds in each triacylglycerol molecule) were calculated to estimate the separations possible. Fractions containing at least 11–14 double bonds per molecule were obtained.
Lability of red blood cell membranes to lipid peroxidation: Application to humans fed polyunsaturated lipids
Authors: Fraga Cesar G. , Tappel A. L. , Leibovitz Brian E. , Kuypers Franz , Chiu Daniel , Iacono James M. , Kelley Darshan S. 
Published: February 2007

AbstractRed blood cell membranes (RBCM) were used to estimate human red blood cell lability to lipid peroxidationin vitro. RBCM were prepared from blood collected from humans fed diets with either 3 or 15% polyunsaturated fatty acids for 80 days. RBCM were isolated by centrifugation, and oxidative stress was induced byin vitro incubation with 0.1 or 0.5 mM tert‐butyl hydroperoxide (t‐BOOH) in the presence of 0.5 mg added hemoglobin. Lipid Peroxidation was evaluated by measurement of thiobarbituric acid‐reactive substances (TBARS). Lipid peroxidation correlated with the protein content of RBCM in both noninduced and t‐BOOH‐induced lipid peroxidation systems. TBARS production was dependent on the amount of t‐BOOH added to the RBCM. The production of TBARS by RBCM incubated with 0.5 mM t‐BOOH was correlated with the arachidonic acid content in the red blood cells (RBC) from which RBCM were prepared. The methodology developed was useful for comparative estimations of the lability of RBCM to lipid peroxidation.
Solubilization and partial purification of cholinephosphotransferase in hamster tissues
Authors: O Kar‐min , Choy Patrick C. 
Published: February 2007

AbstractCDP choline:1,2‐diacylglycerol cholinephosphotransferase (EC 2.7.8.2) is located on the cytoplasmic side of the endoplasmic reticulum, and catalyzes the final step in the synthesis of phosphatidylcholine via the CDP choline pathway. The enzyme was solubilized from hamster liver microsomes by 3% Triton QS‐15, and partially purified by DEAE‐Sepharose chromatography and Sepharose 6B chromatography. The microsomal and partially purified enzymes displayed similar pH profile, and both showed absolute requirement for Mg++ or other divalent cations. The Km values of CDP choline were similar between microsomal and partially purified enzyme, whereas the Km value for diacylglycerol was substantially lowered when the enzyme was partially purified. Hamster heart cholinephosphotransferase was not solubilized by Triton QS‐15.
Lipids in vascular function
Authors: Sellmayer Alois , Hrboticky Nina , Weber Peter C. 
Published: February 2007

AbstractPhysiological and pathological vascular responses depend on the action of numerous intercellular mediators, ranging from hormones to gases like nitric oxide, proteins, and lipids. The last group consists not only of the different types of lipoproteins, but also includes a broad array of other lipophilic signaling molecules such as fatty acids, eicosanoids, phospholipids and their derivatives, sphingolipids and isoprenoids. Due to space limitations, it is impossible to discuss all the vascular effects of lipophilic mediators or compounds. Therefore, we will focus on one of the most important lipid‐mediated diseases, atherosclerosis. Lipoproteins and especially their native or oxidized lipid compounds affect vascular function in many different ways, and these effects do not only modulate atherogenesis but are of paramount physiological and pathophysiological importance in other diseases, such as inflammation, tumor metastasis, or normal wound healing.
Dietary fatty acids and coronary heart disease
Authors: Nordøy Arne 
Published: February 2007

AbstractThe effects of dietary fats have been established in epidemiological and intervention studies and through relationship to risk factors for development of coronary heart disease (CHD). During a period where the impressive effects of hydroxymethylglutaryl‐CoA reductase inhibitors on the mortality of CHD dominate the medical journals, it is important to realize the major effects of dietary fatty acids on a series of events included in the multifactorial disorder of CHD.
Administration of docosahexaenoic acid influences behavior and plasma catecholamine levels at times of psychological stress
Authors: Hamazaki Tomohito , Sawazaki Shigeki , Nagasawa Tetsuro , Nagao Yoko , Kanagawa Yuko , Yazawa Kazunaga 
Published: February 2007

AbstractThe purpose of the present research was to clarify the effect of docosahexaenoic acid (DHA) intake on behavior and plasma catecholamines (CA). In Study 1, 42 students took either DHA‐rich oil capsules containing 1.5–1.8 g DHA/d or control oil capsules containing 97% soybean oil plus 3% of another fish oil for 3 mon in a double‐blind fashion. They took a psychological test (PF Study) at the start and end of the study. This study started at the end of summer vacation and ended just before the final exams. In the control group, external aggression (aggression against others) in PF Study was significantly increased at the end of the study as compared with that measured at the start (+8.9%), whereas it was not significantly changed in the DHA group (−1.0%). In a similar double‐blind study (Study 2), we measured external aggression under nonstressful conditions. External aggression slightly decreased in the control group, whereas there were no significant changes in the DHA group. In Study 3 with 14 students, plasma CA were measured at the start and end of capsule administration period of 2 mon. Subjects were under continuous stress of the final exams that lasted throughout the whole study period. The ratio of plasma epinephrine to norepinephrine concentrations was significantly increased in the DHA group (78%), whereas it stayed at the same level in the control group. In Study 4, mice were fed either DHA‐deficient diet or ‐sufficient diet for 4 wk, and their rearing frequency (an anxiety index) was measured. In the DHA‐sufficient group, the rearing frequency was significantly less than in the other group. These effects of DHA intake may be applied to people in an attempt to ameliorate stress‐related diseases.
n‐3 fatty acids in the prevention of cardiac arrhythmias
Authors: Leaf Alexander , Kang Jing X. , Xiao Yong‐Fu , Billman George E. 
Published: February 2007

AbstractIn animals and probably in humans n‐3 polyunsaturated fatty acids (PUFA) are antiarrhythmic. A report follows on the recent studies of the antiarrhythmic actions of PUFA. The PUFA stabilize the electrical activity of isolated cardiac myocytes by inhibiting sarcolemmal ion channels, so that a stronger electrical stimulus is required to elicit an action potential and the relative refractory period is markedly prolonged. This appears at present to be the probable major antiarrhythmic mechanism of PUFA.
Rats with low levels of brain docosahexaenoic acid show impaired performance in olfactory‐based and spatial learning tasks
Authors: Greiner Rebecca Sheaff , Moriguchi Toru , Hutton Ana , Slotnick Burton M. , Salem Norman 
Published: February 2007

AbstractStudies were carried out to determine if decreased levels of central nervous system docosahexaenoic acid (DHA), a result of consuming an n‐3‐deficient diet, had an effect on learning‐ and memory‐related behaviors in adult male rats. Females were reared on an n‐3‐deficient or n‐3‐adequate diet beginning at 21 d of life. Their male pups, the F2 generation, were weaned to the diet of the dam and tested at 9–12 wk of age. An olfactory‐based discrimination and Morris water maze task were used to assess performance. Whole brain was collected after the behavioral experiments and central nervous system fatty acid content was analyzed in olfactory bulb total lipid extracts. F2 generation male rats consuming the n‐3‐deficient diet had an 82% decrease in DHA compared to rats consuming the n‐3‐adequate diet. The n‐3‐deficient animals made significantly more total errors in a 7‐problem, 2‐odor discrimination task compared to the n‐3‐adequate group. Furthermore, the escape latency in the Morris water maze task was significantly longer for the n‐3‐deficient rats compared to the n‐3‐adequate rats. These results indicate that rats with decreased DHA levels in the central nervous system perform poorer in these tasks compared to rats with higher DHA levels and suggest the presence of learning deficits in these animals.
Regulation of cellular 15‐lipoxygenase activity on pretranslational, translational, and posttranslational levels
Authors: Kühn Hartmut , Heydeck Dagmar , Brinckman Roland , Trebus Frank 
Published: February 2007

AbstractIn mammalian cells, enzymatic lipid peroxidation catalyzed by 12/15‐lipoxygenases is regulated by pretranslational, translational, and posttranslational processes. In rabbits, rats, and mice induction of experimental anemia leads to a systemic up‐regulation of 12/15‐lipoxygenases expression. In addition, interleukins‐4 and ‐13 were identified as strong up‐regulators of this enzyme in human and murine monocyte/macrophages and in the lung carcinoma cell line A549, and the interleukin‐4(13) cell surface receptor as well as the signal transducer and activator of transcription 6 (STATG) appears to be involved in the signal transduction cascade. On the level of translation, 15‐lipoxygenase synthesis is blocked by the binding of regulatory proteins to a characteristic gurnine‐cytosine‐rich repetitive element in the 3′‐untranslated region of the rabbit 15‐lipoxygenase mRNA, and the formation of such 15‐lipoxygenase mRNA/protein complexes was identified as molecular reason for the translational inactivity of the 15‐lipoxygenase mRNA in immature red blood cells. However, proteolytic breakdown of the regulatory proteins which were recently identified as hnRNP K and hnRNP E1 overcomes translational inhibition during later stages of reticulocyte maturation. For maximal intracellular activity, 12/15‐lipoxygenases require a rise in cytosolic calcium concentration inducing a translocation of the enzyme from the cytosol to cellular membranes as well as small amounts of preformed hydroperoxides which act as essential activators of the enzymes. 12/15‐Lipoxygenases undergo irreversible suicide inactivation during fatty acid oxygenation, and this process may be considered an element of down‐regulation of enzyme activity. Suicide inactivation and proteolytic breakdown may contribute to the disappearance of functional 12/15‐lipoxygenase at later stages of erythropoiesis.
New products from the agri‐food industry: The return of n‐3 fatty acids into the food supply
Authors: Simopoulos Artemis P. 
Published: February 2007

AbstractThe meat from animals and fish in the wild, chicken eggs produced under complete natural conditions, and wild plants contain higher amounts of n‐3 fatty acids compared to domesticated or cultivated ones. The composition of meats, fish, and eggs is dependent on animal feed. Fish‐meal, flax, and n‐3 from algae in animal feeds increase the n‐3 fatty acid content of egg yolks and lead to the availability of n‐3 fatty acidenriched eggs in the marketplace. Research is ongoing for the production of n‐3 fatty acid‐enriched products from poultry, beef, lamb, pork, milk, bakery products, etc. In the case of n‐3 fatty acid‐enriched eggs, the egg under complete natural conditions (Greek or Ampelistra egg) can serve as a guide for proper composition. Otherwise, the amount of n‐3 fatty acids is determined by the organoleptic properties of the products. It is essential in the process of returning the n‐3 fatty acids into the food supply that the balance of n‐6/n‐3 fatty acids in the diet that existed during evolution is maintained. Clinical investigations confirm the importance of n‐3 fatty acids for normal function during growth and development and in the modulation of chronic diseases. The availability of n‐3 fatty acid‐enriched products should lead to improvements in the food supply. Pregnant and lactating women and infants should benefit since their diet is deficient in n‐3 fatty acids, especially for the vegetarians among them. Studies with n‐3‐enriched eggs lower cholesterol levels, platelet aggregation, and blood pressure. Since cardiovascular disease, hypertension, and autoimmune, allergic, and neurological disorders appear to respond to n‐3 fatty acid supplementation, a diet balanced in n‐3 and n‐6 fatty acids consistent with the diet during human evolution should decrease or delay their manifestation.
Intestinal absorption of unconjugated dihydroxy bile acids: Non‐mediation by the carrier system involved in long chain fatty acid absorption
Authors: Stremmel Wolfgang , Hofmann Alan F. 
Published: February 2007

AbstractExperiments were performed using isolated mucosal cells from the rat jejunum or using the perfused jejunum in the anesthetized rat to test whether lipophilic unconjugated dihydroxy bile acids are absorbed from the proximal small intestine via the same carrier mechanism involved in the uptake of long chain fatty acids. With isolated jejunal mucosal cells, the cellular uptake rate of deoxycholic acid or chenodeoxycholic acid increased linearly with time, showed no evidence of saturation, and was not decreased by the presence of a monospecific antibody to the membrane fatty acid binding protein. In contrast, oleate uptake was saturable, was inhibited by the same antibody, but was not affected by the presence of chenodeoxycholic acid or deoxycholic acid. Bile acid uptake by isolated enterocytes occurred at one‐eighth the rate of fatty acid uptake if expressed in relation to total solute concentration; if expressed in relation to monomeric concentration, initial bile acid uptake was four orders of magnitude slower than fatty acid uptake. In the isolated perfused jejunal segment, chenodeoxycholic acid and deoxycholic acid uptake was not influenced by the presence of the antibody to membrane fatty acid binding protein, whereas absorption of oleate was inhibited by more than 70%. These experiments indicate that absorption of unconjugated lipophilic dihydroxy bile acids in the rodent jejunum does not involve the carrier mediated uptake mechanism involved in the absorption of long chain fatty acids—the mechanism is likely to be passive nonionic diffusion.
The uptake of (R,R,R)α‐tocopherol by human endothelial cells in culture
Authors: Chan Alvin C. , Tran Khai 
Published: February 2007

AbstractEndothelial cells from human umbilical cord vein in culture incorporate physiological and pharmacological amounts of (R,R,R)α‐tocopherol in a time‐dependent and dose‐dependent manner. Incorporated tocopherol was found to associate predominantly with membrane fractions of the cell. When expressed on the basis of organelle protein, the highest amount of tocopherol was found in plasma membrane, and decreasing amounts in mitochondria, endoplasmic reticulum and cytosol. With the relatively wide range of tocopherol concentrations used in these studies (23.2–92.8 μM), there was no apparent toxicity on the cells as judged by unaltered cell numbers and cell viability. When the cells were enriched with tocopherol and cell tocopherol levels were monitored in tocopherol‐free medium, there was a rapid phase of tocopherol disappearance, which was followed by a slower phase. The half‐time for the disappearance of incorporated tocopherol was found to be approximately 65±8.6 hr (mean±SD, n=3). The results of this study clearly show that human endothelial cells in culture are a feasible model for the study of vitamin E uptake. The cell culture model could potentially be used to study other fat‐soluble vitamins and essential nutrients.
Effects of dietary fish oil on biliary phospholipids and prostaglandin synthesis in the cholesterol‐fed pairie dog
Authors: Booker Michael L. , Scott Thayer E. , La Morte Wayne W. 
Published: February 2007

AbstractCholesterol gallstone formation in the prairie dog is accompanied by an increase in the percentage of biliaryphospholipids containing arachidonic acid, and an increase in gallbladder prostaglandin (PG) synthesis, but the pathogenetic significance of these changes is unclear. Dietary supplementation with eicosapentaenoic acid (EPA), an omega‐3 fatty acid which is commonly found in fish oil, decreases prostaglandin synthesis in some tissues by replacing arachidonic acid, and by competitively inhibiting prostaglandin synthesis. We studied the effect of dietary fish oil on gallbladder PG synthesis, and the relative abundance of various molecular species of phosphatidylcholines and phosphatidylethanolamines in bile and gallbladder epithelium in the cholesterol‐fed prairie dog. Prairie dogs were maintained for 4 weeks on one of four diets: i) control, ii) cholesterol‐supplemented (0.34%), iii) menhaden oil (50 g/kg chow), or iv) cholesterol plus menhaden oil. Supplementation with menhaden oil resulted in a replacement of arachidonic and linoleic acids with EPA and docosahexaenoic acids in the phospholipids of bile and gallbladder mucosa. In cholesterol‐fed animals, supplementation with menhaden oil prevented increased gallbladder PG synthesis. Menhaden oil also reduced the incidence of cholesterol monohydrate crystals among cholesterol‐fed animals (9/20 with cholesterol plus menhaden oil vs 21/22 with cholesterol alone), but the improvement could not clearly be attributed to decreased PG synthesis since supplementation with menhaden oil also increased the total phospholipid concentration in bile, and decreased the degree of cholesterol saturation. These results demonstrate that dietary supplementation with omega‐3 fatty acids significantly influences biliary phospholipids, and decreases the incidence of cholesterol monohydrate crystal formation in this animal model.
Autoxidation of polyunsaturated triacylglycerols. I. Trilinoleoylglycerol
Authors: Neff W. E. , Frankel E. N. , Miyashita K. 
Published: February 2007

AbstractThe hydroperoxides and secondary products formed from trilinoleoylglycerol autoxidized at 40°C were isolated and characterized to clarify their contribution to oxidative deterioration of vegetable oils. The products were purified by high performance liquid chromatography (HPLC) and identified, as intact triacylglycerols, by ultraviolet, infrared,1H NMR and13C NMR analyses, and after derivatization by lipolysis, gas chromatography, and gas chromatography‐mass spectrometry. The main, primary products included mono‐,bis‐ and tris‐9‐hydroperoxy‐trans‐10,cit‐12‐; 9‐hydroperoxy‐trans‐10,trans‐12; 13‐hydroperoxy‐cis‐9,trans‐11; and 13‐hydroperoxy‐trans‐9,trans‐11‐linolenoyl glycerols. The structures of the minor secondary products analyzed after derivatization were consistent with known oxidative degradation products of linoleate hydroperoxides. HPLC analyses showed that thebis‐ and tris‐hydroperoxides were formed from the mono‐hydroperoxides during autoxidation at peroxide values above 18 and 28 meq/kg. Studies on the further oxidation of the mono‐hydroperoxides support a mechanism for the consucutive formation ofbis‐ and tris‐hydroperoxides from the monohydroperoxides. HPLC analyses showed that no preferential oxidation occurred between the 1(3)‐ and 2‐triglyceride positions. Hydroperoxides of linoleate triacylglycerols may be important precursors of volatile compounds contributing to off‐flavors of vegetable oils.