bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reversibility of cholinephosphotransferase in lung microsomes
Authors: Tsao Francis H. C. 
Published: November 2006

AbstractThe 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

AbstractStudies 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

AbstractGroups 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

AbstractThe 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

AbstractIncorporation 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

AbstractThe 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

AbstractThe 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

AbstractReaction 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

AbstractThe 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.
Fatty acid composition of fats of differing melting points extracted from ram subcutaneous tissue
Authors: Johnson Cecil B. , Purchas Roger W. , Birch E. John 
Published: November 2006

AbstractThe observation that the subcutaneous fat of pasture‐fed Southdown rams consists of two distinct regions is reported. Fatty acid composition of fat from the outer and inner regions of subcutaneous tissue taken from the rib region of eight Southdown rams fed pasture were determined. Relative to the harder inner regions (mean melting point 43.1°C), the softer outer regions (mean melting point 31.8°C) were shown to contain more 9∶0‐, 15∶0‐, 17∶0‐, 17∶1‐, 18∶1‐cis and total 18∶1 fatty acids; less 14∶0‐, 16∶0‐, 18∶0‐ and 18∶1‐trans fatty acids; and a greater variety and a greater concentration of branched‐chain components. Proportions of medium chain‐length fatty acids other than 9∶0, did not differ between the layers.The fatty acid contents of serial samples taken at 1‐mm intervals through these tissues were determined. Changes in concentrations of components among samples were gradual through the tissues. There was no clear connective tissue sheet, as has been reported for pigs. The inner region of the tissues contains apparently nonrandom fluctuating changes in fatty acid composition.
Effect of various steroids on the biosynthesis of arachidonic acid in isolated hepatocytes and HTC cells
Authors: Marra Carlos A. , de Alaniz María J. T. , Brenner Rodoifo R. 
Published: November 2006

AbstractThe effect of various steroids on the incorporation and desaturation of eicosa‐8,11,14‐trienoic acid in normal hepatocytes and HTC cells was investigated. After 3 hr incubation with 11‐deoxycorticosterone, both kinds of cells showed an increase in the incorporation of eicosatrienoic acid. In contrast, progesterone, cortexolone, 17‐β‐estradiol, testosterone, estriol, aldosterone, corticosterone, dexamethasone, dehydroepiandrosterone, 11‐β‐hydroxyandrosterone, 11‐ketoaetiocholanolone, epiaetiocholanolone and 5‐β‐pregnane‐3α,20α‐diol, provoked no significant changes in the uptake of the exogenous acid. Of all the steroids tested, only 11‐dexycorticosterone, dexamethasone and 17‐β‐estradiol evoked a significant inhibition on the arachidonate biosynthesis in both kinds of cells. Testosterone, estriol, aldosterone and corticosterone provoked a significant inhibition of Δ5‐desaturase in HTC cells. In dexamethasone, this effect was dose‐dependent (0 to 10−4 M). Simultaneous incubation with 17‐β‐ estradiol or 11‐deoxycorticosterone with dexamethasone led to an extent of inhibition on arachidonate biosynthesis that did not surpass the effect of each drug. Pretreatment of isolated hepatocytes with the antiglucocorticoid, cortexolone, prevented the dexamethasone‐induced inhibition of arachidonate biosynthesis. Normal rat liver microsomes preincubated in vitro with dexamethasone, 11‐deoxycorticosterone, 17‐β‐estradiol, corticosterone or estriol (10−6 or 10−4 M concentration), showed no significant changes in the Δ5‐desaturase activity. The results obtained suggest that the effect of the steroids on arachidonic acid biosynthesis in normal hepatocytes and HTC cells requires receptor occupancy and probably is mediated through a common biochemical mechanism.
A diet containing n−3 and n−6 fatty acids favorably alters the renal phospholipids, eicosanoid synthesis and plasma lipids in nephrotic rats
Authors: Barcelli U. O. , Beach D. C. , Thompson B. , Weiss M. , Pollak V. E. 
Published: November 2006

AbstractThe nephrotic syndrome was induced in rats by intravenous adriamycin (3 mg/kg). The rats were then divided into four groups which, for six weeks, were pair‐fed diets containing beef tallow (BT), fish oil (FO), a source of n−3 fatty acids, evening primrose oil (EPO), a source of n−6 fatty acids, or a combination of evening primrose oil and fish oil, 75∶25 (EPO:FO). The fat content of the diets was 15%. Significant incorporation of the fatty acids into kidney phospholipids was demonstrated. Diets containing FO, EPO and EPO:FO lowered plasma triglycerides and total cholesterol levels as compared with diets containing BT. Only EPO:FO raised high density lipoprotein (HDL) cholesterol levels, as compared with BT. The combination EPO:FO prevented the tenfold suppression of aortic 6‐keto‐PGF1α caused by FO. These changes in plasma lipids and eicosanoid production are potentially antiatherogenic and may prevent glomerular sclerosis. The combination of EPO and FO, containing n−6 and n−3 fatty acids may offer advantages over either family of fatty acids in this model of nephrotic syndrome.
The composition of red cell membrane phospholipids in Canadian Inuit consuming a diet high in marine mammals
Authors: Innis Sheila M. , Kuhnlein Harriet V. , Kinloch David 
Published: November 2006

AbstractA study of the fatty acid composition of red cell phosphatidylcholine and phosphatidylethanolamine and serum cholesterol was undertaken in 185 Canadian Inuit (age 2 months‐82 years). Samples from 24 Canadian men and women (21–50 years) living in Vancouver were also analyzed as a reference for the Inuit in this age range. Dietary survey of the Inuit community (325 Inuit) demonstrated a diet based on traditional foods in which the principal source of n−3 fatty acid was marine mammal flesh (mean intake: 164 g/person/day) rather than fish (mean intake: 13 g/person/day). Compared to the Vancouver samples, the Inuit phosphatidylethanolamine had higher 20∶5n−3 and 22∶6n−3 and lower 20∶4n−6, but similar 18∶2n−6 levels. The level of 20∶5n−3 was higher and 20∶4n−6 was lower in the Inuit than in the Vancouver red cell phosphatidylcholine. Despite these differences in percentage content of C20 and C22 n−6 and n−3 fatty acids, the mean chain length and unsaturation index of the Inuit and Vancouver red cell phosphatidylcholine and phosphatidylethanolamine were very similar. Serum cholesterol concentration showed no sex difference within the Inuit, and no difference from Vancouver men and women of similar age. The analyses suggest that the fatty acid composition of the Inuit red cell phospholipids are primarily a reflection of their diet‐fat composition.
Formation of fluorescent substances from degradation products of methyl linoleate hydroperoxides with amino compound
Authors: Iio Toshihiro , Yoden Kazuaki 
Published: November 2006

AbstractThe degradation products formed from methyl linoleate hydroperoxides by reaction with heme were fractionated by Sephadex LH‐20 column chromatography and by reverse‐phase high performance liquid chromatography, and the ability of each compound to form fluorescent substances through reaction with amino compound was compared. Maximum formation of fluorescent substances was obtained from monomeric degradation products with amino compound, but low molecular weight aldehydes such as hexanal, 2‐hexenal and 2,4‐decadienal, formed only a small amount of fluorescent substances. However, the major monomeric degradation products described previously, the hydroxy‐, keto‐ and epoxy‐derivatives, do not significantly contribute to the formation of fluorescent substances through reaction with amino compound. It was suggested that formation of fluorescent substances from lipid peroxides with amino compound may originate from a precursor present in monomeric degradation products formed from hydroperoxide of methyl linoleate during lipid peroxidation, and that low molecular weight aliphatic aldehydes are not involved in fluorescent substance formation. Moreover, the majority of TBA‐reactive substances in secondary oxidation products prepared from autoxidized methyl linoleate are also unrelated to the formation of fluorescent substances through reaction with amino compound.
Predicting coordinated lipid biosynthesis: Application to the surfactant‐accommodated epidermis
Authors: Ando Howard Y. , Gazdick Gary G. G. , Sugita Edwin T. , Schnaare Roger L. 
Published: November 2006

AbstractFactorialized correlation analysis is proposed as a method for predicting the coordination of multiple enzyme pathways. The approach can be used potentially to find new relationships and to predict relationships that have been established in other tissues. However, careful tracer studies are needed to verify the cause‐and‐effect relationships between precursor and products. In this study, guinea pigs that were chronically treated with an anionic, a nonionic and a cationic surfactant passed through an irritation stage to a clinical state that appeared normal. The method was used to examine binary coordination of lipid biosynthesis in the epidermis by using a factorialized table of regression coefficients. Coordinated lipid relationships that have been reported in other tissues were predicted between sphingomyelin and cholesterol, as well as between phosphatidylcholine, phosphatidylserine and phosphatidylethanolamine. A new inverse relationship was found between triglycerides and both sphingomyelin and cholesterol, using this method. These data are discussed with respect to a membrane fluidization model for the accommodated state.
Quantification of oxysterols in dutch foods: Egg products and mixed diets
Authors: van de Bovenkamp Peter , Kosmeijer‐Schuil Truus G. , Katan Martijn B. 
Published: November 2006

AbstractA sensitive and specific method is described for quantifying various cholesterol oxidation products in foodstuffs, including 7β‐hydroxycholesterol, cholesterol‐α‐epoxide, cholestane‐triol, 7‐ketocholesterol and 25‐hydroxycholesterol. A chloroform‐methanol extract of the food was fractionated over two successive silica columns. Two fractions containing different classes of oxysterols were then analyzed as trimethylsilyl derivatives by capillary gas liquid chromatography, using on‐column injection and a temperature gradient from 70 to 200°C. The detection limit was about 0.5 μg/g dry weight for egg yolk powder. Fresh egg yolk contained only 1.2 μg/g of total oxides per g dry weight, showing that artifactual oxidation during the procedure was minimal. Recovery of 5 pure oxysterols added to egg yolk at levels of 6.5 and 10 μg/g was between 93 and 102%. In commercial egg yolk and whole egg powder stored for one year, total amounts of oxysterols ranging from 21 to 137 μg/g dry weight were found. In duplicates of mixed Dutch diets, total amounts ranged from 3.6 to 6.2 μg/g dry weight. Duplicates containing mostly fried and baked foods did not have higher levels than duplicates in which foods had been prepared by boiling or left raw. We conclude that a normal mixed diet provides only minor amounts of cholesterol oxidation products.
Characterization of 12‐methyl‐cis‐4‐tetradecenoic acid fromCorynebacterium sepedonicum
Authors: Henningson Paul J. , Vick Brady A. , Bugbee William M. , Gudmestad Neil C. 
Published: November 2006

AbstractA previously uncharacterized fatty acid found inCorynebacterium sepedonicum was analyzed by gas chromatography‐mass spectrometry and infrared spectrometry and determined to be 12‐methyl‐cis‐4‐tetradecenoic acid. This fatty acid represents nearly 6% of the total fatty acids ofC. sepedonicum, but it is present at significantly lower levels in otherCorynebacterium species. Therefore, 12‐methyl‐cis‐4‐tetradecenoic acid provides a useful marker in distinguishingC. sepedonicum from other microorganisms.