bluuebunny/crossref_metadata_2025_split huggingface dataset:
An improved method for the measurement of malondialdehyde in biological samples
Authors: Li Xiu‐Yan , Chow Ching K. 
Published: November 2006

AbstractAn improved method was developed for measuring malondialdehyde (MDA) as its thiobarbituric acid (TBA) complex. Samples were initially incubated with 1% potassium iodide and 0.1% butylated hydroxytoluene at 50°C for 20 min, and then with 0.4% TBA at 60°C for 60 min. The MDA‐TBA complex formed was extracted with isobutyl alcohol and measured by high‐performance liquid chromatography with fluorescence detection. The improved method allows for a more specific determination of MDA present in biological samples.
Molecular species of choline and ethanolamine glycerophospholipids in rat brain myelin during development
Authors: Leray C. , Sarliève L. L. , Dreyfus H. , Massarelli R. , Binaglia L. , Freysz L. 
Published: November 2006

AbstractThe composition of the molecular species of various phospholipid subclasses was examined in myelin isolated from brain of 15‐, 21‐ and 90‐day‐old rats. The molecular species of diacylglycerophosphocholine (PtdCho), diacylglycerophosphoethanolamine (PtdEtn) and plasmenylethanolamine (PlsEtn) were quantified by high‐performance liquid chromatography (HPLC) after phospholipase C treatment and dinitrobenzoyl derivatization. In rat brain myelin, each phospholipid subclass showed a specific pattern of molecular species that changed during development. PtdCho contained large amounts of saturated/monounsaturated and disaturated species and low amounts of saturated/polyunsaturated species. During brain development, the levels of saturated/monounsaturated molecular species increased whereas those of the disaturated and saturated/polyunsaturated species decreased. PtdEtn were characterized by their low levels of disaturated species and a high content of saturated/monounsaturated and saturated/polyunsaturated species, of which those containing fatty acids of the n−3 series decreased, whereas those containing fatty acids of the n−6 series did not change during brain development. The levels of saturated/monounsaturated species increased in PtdEtn. No disaturated molecular species could be detected in PlsEtn. This alkenylacyl subclass contained large amounts of saturated/polyunsaturated, saturated/monounsaturated and dimonounsaturated molecular species. During development, the levels of saturated/polyunsaturated molecular species decreased while those of the two others increased. The data indicated that myelin sheaths undergo phospholipid changes during brain development and maturation.
Sterol synthesis and viability oferg11 (cytochrome P450 lanosterol demethylase) mutations inSaccharomyces cerevisiae andCandida albicans
Authors: Bard M. , Lees N. D. , Turi T. , Craft D. , Cofrin L. , Barbuch R. , Koegel C. , Loper J. C. 
Published: November 2006

AbstractThe identification of the precise structural features of yeast sterol molecules required for the essential “sparking” function has been a controversial area of research. Recent cloning and gene disruption studies inSaccharomyces cerevisiae have shown that C‐24 methylation (ERG6), C‐5 desaturation (ERG3) and Δ8‐Δ7 isomerization (ERG2) are not required, while C‐14 demethylation (ERG11) and C‐14 reduction (ERG24) are each required for aerobic viability. Earlier observations had indicated that C‐14 demethylase deficient strains could be restored to aerobic growth by suppressor mutations that caused a deficiency in C‐5 desaturase. These strains were reported to synthesize some ergosterol, indicating that they contained leaky mutations in bothERG11 andERG3, thereby making it imposssible to determine whether the removal of the C‐14 methyl group was required for aerobic viability. The availability of theERG11 andERG3 genes has been used in this study to construct strains that contain null mutants in bothERG11 andERG3. Results show that these double disruption strains are viable and that spontaneously arising suppressors of theERG11 disruption areerg3 mutants. Theerg11 mutants ofS. cerevisiae are compared to similar mutants ofCandida albicans that are viable in the absence of theerg3 lesion.
Phospholipid and fatty acid compositions ofRhizobium leguminosarum biovartrifolii ANU843 in relation to flavone‐activated pSymnod gene expression
Authors: Orgambide Guy G. , Huang Zhi‐Heng , Gage Douglas A. , Dazzo Frank B. 
Published: November 2006

AbstractThe phospholipid and associated fatty acid compositions of the bacterial symbiont of clover,Rhizobium leguminosarum biovartrifolii wild‐type ANU843, was analyzed by two‐dimensional silica thin‐layer chromatography, fast atom bombardment‐mass spectrometry, flame‐ionization detection gas‐liquid chromatography and combined gas‐liquid chromatography/mass spectrometry. The phospholipid composition included phosphatidylethanolamine (15%),N‐methylphosphatidylethanolamine (47%),N,N‐dimethylphosphatidylethanolamine (9%), phosphatidylglycerol (19%), cardiolipin (5%) and phosphatidylcholine (2%). Fatty acid composition included predominantlycis‐11‐octadecenoic acid, lower leves ofcis‐9‐hexadecenoic acid, hexadecanoic acid, 11‐methyl‐11‐octadecenoic acid, octadecanoic acid, 11,12‐methyleneoctadecanoic acid, eicosanoic acid and traces of branched, and di‐ and triunsaturated fatty acids. The influence of expression of the “nodulation” genes encoding symbiotic functions on the composition of these membrane lipids was examined in wild‐type cells grown with or without the flavone inducer, 4′,7‐dihydroxyflavone and in mutated cells lacking the entire symbiotic plasmid where these genes reside, or containing single transposon insertions in selected nodulation genes. No significant changes in phospholipid or associated fatty acid compositions were detected by the above methods of analysis.
Age, sex and source of hamster affect experimental cholesterol cholelithiasis
Authors: Ayyad Nariman , Cohen Bertram I. , Mosbach Erwin H. , Miki Shigeo , Mikami Takahiro , Mikami Yasuko , Stenger Richard J. 
Published: November 2006

AbstractIn the present study, we examined the effect of the following factors on a hamster model of cholesterol cholelithiasis: (i) the source of the golden Syrian hamsters (Sasco, Omaha, NE or Charles River, Wilmington, MA), (ii) the sex of the experimental animals and (iii) their age (4 wkvs. 8 wk of age). All hamsters were fed a semipurified diet which contained cholesterol (0.3%) and palmitic acid (1.2%). No cholesterol gallstones formed in any of the female hamsters regardless of age or source. The 4‐week‐old male hamsters from Sasco had the greatest incidence of gallstones (93%). The 8‐week‐old male hamsters tended to have a lower incidence of cholesterol gallstones than the younger ones, regardless of the commercial supplier (67vs. 93% for Sasco and 27vs. 40% for Charles River). Female hamsters has higher liver and serum cholesterol levels than the male hamsters; Charles River hamsters had lower serum cholesterol concentrations than the Sasco animals. Total biliary lipid concentrations were highest in Sasco male hamsters, but biliary cholesterol (mol%) was lower in the males than in the females (4.2–4.5%vs. 6.1–7.1%) regardless of age. The cholesterol saturation indices were higher in the Sasco females than the corresponding males; these values were lower in the Sasco hamsters than the Charles River animals, regardless of age or sex. The male Sasco hamsters had a higher total biliary bile acid concentration (98.9 mg/mL) than the Sasco females (58.9 mg/mL) and the Charles River animals (24.6% mg/mL for males and 38.2 mg/mL for females). The percentage of chenodeoxycholic acid in bile was significantly lower, and the percentage of cholic acid was higher in all females as compared to males. We conclude that there is a sex, age and “strain” difference in cholesterol cholelithiasis in hamsters; it is important to consider these factors when working with the hamster model of gallstone disease. All female hamsters were markedly resistant to the induction of cholesterol gallstone disease.
Preferential reduction in adipose tissue α‐linolenic acid (18∶3ω3) during very low calorie dieting despite supplementation with 18∶3ω3
Authors: Tang Anna B. , Nishimura Karen Y. , Phinney Stephen D. 
Published: November 2006

AbstractWe have previously reported that the relative content of 18∶3ω3 in adipose triglyceride (TG) of women was reduced following major weight loss while on a very low calorie diet (VLCD). In an attempt to prevent this loss of 18∶3ω3 reserves, we have tested two VLCD supplemented with varying amounts of 18∶3ω3. The formula (FORM) and food VLCD (2.1–3.0 MJ or 500–700 kcal/d) contained 20 g/d of fat and provided the recommended dietary allowance for minerals and vitamins. FORM subjects (Group 1) were 5 women [initial body mass index (BMI) of 36.8, 168% ideal body weight (IBW) who received 20 g/d of canola oil (1.6 g 18∶3ω3). Their mean weight loss was 23.9 kg in a 4–5 mon period. Food VLCD subjects (Group 2) were 6 women (BMI 33.9, 155% IBW) supplemented with 2 g/d of linseed oil (1.1 g 18∶3ω3). Their mean weight loss was 17.4 kg in a 2–3 mon period. Needle biopsies of adipose tissue were obtained from Group 1 before, at midpoint and after weight loss; and from Group 2 before and after weight loss. The adipose TG and serum (Group 1) were separated and their fatty acid composition determined by thin‐layer and gas chromatography. In Group 1, adipose 18∶3ω3 fell from 0.65 to 0.59 wt%, then to 0.52 wt% during weight loss. In Group 2, it fell from 0.77 to 0.64 wt%. The fall in adipose 18∶3ω3 with weight loss was significant atP=0.01 (Group 1) andP<0.01 (Group 2). There were no differences between responses to the 1.1 g/d or 1.6 g/d 18∶3ω3 supplements. The relative content of 18∶3ω3 in serum free fatty acids from Group 1 was reduced after major weight loss. Thus, in both groups the ω3 supplementation did not help to maintain adipose tissue 18∶3ω3 during rapid weight loss, and its decrement may affect circulating lipid pools. As adipose 18∶2ω6 did not change with weight loss, this reduction in the ratio of ω6 precursor to ω3 precursor could eventually alter the balance of their products as well.
An increased incidence of apolipoprotein E2/E2 and E4/E4 in retinitis pigmentosa
Authors: Huq Lubna , McLachlan Tracey , Hammer Harold M. , Bedford Dorothy , Packard Christopher J. , Shepherd James , Converse Carolyn A. 
Published: November 2006

AbstractPrevious studies from our laboratory have shown that retinitis pigmentosa (RP), a family of hereditary retinal degenerations, is often accompanied by abnormal levels of cholesterol or polyunsaturated fatty acids. The requirement of the retina for n−3 fatty acids is well known, and a defect in the supply of these lipids (e.g., by apolipoproteins) could affect the course of the disease. The present study confirms and extends a report on apolipoprotein E (apo E) isoforms in German RP patients [Jahn, Oette, Esser, Bergmann, and Leiss, (1987)Ophthalmic Res. 19, 285–288] which showed a tenfold increased frequency of the E2/E2 phenotype compared to the average German population. In our study, apo E phenotypes were determined in the probands of 100 Scottish RP families. The findings revealed a 4‐fold increase in the incidence of E2/E2 and an 8‐fold increase in E4/E4 compared to a Scottish control population. These increases were statistically significant at theP<0.05 andP<0.01 levels, respectively. To investigate the possibility that some of these apparent E2/E2 or E4/E4 phenotypes might actually be new apo E mutations, we examined the behavior of the apo E on sodium dodecyl sulfate‐polyacrylamide gels (E2 migrates anomalously) and on isoelectric focusing gels following cysteamine modification of cysteines. These studies showed that two RP patients possibly had new apo E mutations, though amino‐terminal sequence analysis revealed no changes in the sequence of the first 19 residues; further sequence analysis is obviously warranted.
Synthesis of oxygenated fatty acid esters from santalbic acid ester
Authors: Pasha Mohammed Khysar , Ahmad Fasih 
Published: November 2006

AbstractThe reaction of methyl octadec‐trans‐11‐en‐9‐ynoate (1) with mercuric sulfate in the presence or absence of sulfuric acid is described. Treatment of 1 with mercuric sulfate in absolute methanol yielded methyl 9(10)‐oxoocta‐dec‐trans‐11‐enoates (Product A). This product, upon treatment withm‐chloroperbenzoic acid, afforded methyltrans‐11,12‐epoxy‐9‐oxooctadecanoate (4) and methyl 10‐oxooctadec‐trans‐11‐enoate (2). Sodium borohydride reduction of A furnished the corresponding hydroxy esters. The treatment of 1 with mercuric sulfate in the presence of sulfuric acid gave as major product methyl 9(10)‐oxo‐11(12)‐methoxyoctadecanoates and methyl 9(10)‐oxoocta‐dec‐trans‐11‐enoates as a minor product. When methyl 11,12‐epoxyoctadec‐9‐ynoate was reacted with acid in methanol, methyl 12‐hydroxy‐11‐methoxyoctadec‐9‐ynoate was formed, which on treatment with zinc chloride in CCl4 yielded methyl 9,12‐epoxyoctadec‐9,11‐dienoate exclusively. The preparation of oxo fatty esters from the total methyl esters ofSantalum album was also demonstrated. The structures of the products were established by chemical derivatization and spectral characterization.
Rat liver outer mitochondrial carnitine palmitoyltransferase activity towards long‐chain polyunsaturated fatty acids and their CoA esters
Authors: Gavino Grace R. , Gavino Victor C. 
Published: November 2006

AbstractThe activity of the overt form of rat liver mitochondrial carnitine palmitoyltrasferase or CPT0 (EC 2.3.1.21) towards different fatty acid substrates was studied. The following non‐esterified fatty acids (NEFA) and their CoA esters in the presence of 1% bovine serum albumin (BSA) were tested: 16∶0, 18∶0, 18∶1, 18∶2, 18∶3ω3, 20∶4, 20∶5ω3 and 22∶6ω3. The data fit a square hyperbolic model for enzyme catalysis (p<0.001, non‐linear regression). Asymptotic Vmax and K0.5, substrate concentration at one‐half Vmax, were calculated using total concentrations of acyl‐CoA, or unbound concentrations of NEFA. BSA was found to act as a true substrate reservoir for NEFA in that the dissociation of the NEFA‐BSA complex was 10–330 times faster than the CPT0 reaction. Regardless of form (NEFA or CoA ester), 18∶3ω3 gave the highest, while 22∶6ω3 and 18∶0 gave the lowest rates of acylcarnitine synthesis. Except for 18∶3ω3 and 18∶2, Vmax for NEFA was generally lower than for acyl‐CoA, with the greates differences observed for 20∶4, 20∶5ω3 and 22∶6ω3, suggesting that acyl‐CoA synthesis may also be important in the control of the entry of these fatty acids into the mitochondria. The data provide an enzymatic rationale for the relatively low content of 18∶3ω3 in esterified lipid.
Thermal adaptation in biological membranes: Functional significance of changes in phospholipid molecular species composition
Authors: Hazel Jeffrey R. , Williams E. Eugene , Livermore Rochelle , Mozingo Nancy 
Published: November 2006

AbstractQuantities of 1‐palmitoyl 2‐docosahexaenoyl phosphatidylcholine (16∶0/22∶6‐PC or PDPC) increase from 24 to 40 weight percent as a consequence of cold acclimation in mitochondrial membranes of rainbow trout liver (J. Comp. Physiol. 156, 665–674, 1986). The present study was undertaken to assess the impact of such a large change in the proportions of a single molecular species on the fluidity, lateral packing (as sensed by phospholipase A2), and permeability of biological membranes. These properties were examined in multilamellar liposomes prepared from binary mixtures of dipalmitoyl phosphatidylcholine (DPPC) and PDPC in proportions increasing from 10 to 40 mole% PDPC. Glucose permeability was positively correlated with both assay temperature and PDPC content. The temperature dependence of Na+ permeability declined steadily as the mole fraction of PDPC increased; consequently, sodium permeability was positively correlated with PDPC content at 5°C, but inversely correlated at 20°C. Phospholipase A2 activity was independent of both assay temperature and vesicle composition. Vesicles of all compositions displayed a single transition in the temperature dependence of 1,6 diphenyl‐1,3,5‐hexatriene (DPH) fluorescence polarization, which shifted to lower temperature and broadened as proportions of PDPC increased. At temperatures belowthe transition, fluidity was positively correlated with the mole fraction of PDPC, but interfacial and deeper regions of the bilayer were affected differently by variations in PDPC content. Nonelectrolyte permeability was the only index of membrane structure or function to be significantly correlated with the fluidity of the bilayer interior. The tendencies of PDPC to both fluidize the membrane and to reduce the temperature sensitivity of electrolyte permeation may promote the adaptation of membrane function to low temperature.
Hydrolysis of neutral lipid substrates by rat hepatic lipase
Authors: Wilcox Rebecca W. , Thuren Tom , Sisson Patricia , Kucera Gregory L. , Waite Moseley 
Published: November 2006

AbstractRat hepatic lipase, an enzyme whose involvement in the catabolism of lipoproteins remains poorly defined, has both neutral lipid and phospholipid hydrolyzing activity. We determined the substrate specificity of hepatic lipase for 1‐oleoyl‐sn‐glycerol, 1,2‐dioleoyl‐sn‐glycerol, and 1,3‐dioleoyl‐sn‐glycerol in the Triton X‐100 mixed micellar state, and compared these results to those obtained previously in our laboratory for the phospholipid substrates phosphatidic acid (PA), phosphatidylethanolamine (PE), and phosphatidylcholine (PC). Vmax values were determined by diluting the substrate concentration in the surface of the micelle by Triton X‐100. The Vmax values obtained were 144 μmol/min/mg for 1‐oleoyl‐sn‐glycerol, 163 μmol/min/mg for 1,2‐dioleoyl‐sn‐glycerol, and 145 μmol/min/mg for 1,3‐dioleoyl‐sn‐glycerol. These values were higher than those obtained earlier for phospholipids which were 67 μmol/min/mg for PA, 50 μmol/min/mg for PE and 4 μmol/min/mg for PC. In addition, the mole fraction of lipid substrate at half maximal velocity (K) in the surface dilution plot was lower for the neutral lipid substrates as compared to those obtained for the phospholipid substrates. When the hydrolysis of 1,3‐dioleoyl‐sn‐glycerol mixed micelles was studied as a function of time, cleavage at thesn‐1 andsn‐3 positions occurred at the same rate, suggesting that hepatic lipase is not stereo‐selective with respect to 1,3‐diacyl‐sn‐glycerol substrates. To determine if the presence of one lipid could affect the hydrolysis of the other, all possible dual combinations of 1‐oleoyl‐sn‐glycerol, 1,2‐dioleoyl‐sn‐glycerol, and 1,3‐dioleoyl‐sn‐glycerol, in the same micelle were made and the hydrolysis rate of each substrate was determined. Interaction occurred only for the 1,2‐dioleoyl‐sn‐glycerol/1,3‐dioleoyl‐sn‐glycerol mixture where the hydrolysis of 1,2‐dioleoyl‐sn‐glycerol was slightly inhibited and that of 1,3‐dioleoyl‐sn‐glycerol slightly activated compared to the predicted theoretical rate. These findings demonstrate that when presented in similar physical states, the neutral lipid substrates tested were hydrolyzed at a higher rate by hepatic lipase than the phospholipid substrates.
Lipoprotein lipase in rats fed fish oil: Apparent relationship to plasma insulin levels
Authors: Baltzell Janet K. , Wooten Joseph T. , Otto David A. 
Published: November 2006

AbstractTo investigate the role of lipoprotein lipase (LPL) and hepatic lipase in the triacylglycerol lowering effects of fish oil, rats were fed lard (L), corn oil (CO) or menhaden oil (MO) as the primary fat source in otherwise identical diets. After 2 weeks, soleus muscle LPL differed between groups (MO>CO>L). Hepatic lipase did not differ between CO‐ and MO‐fed rats but was elevated in L‐fed rats. Adipose LPL did not differ between diet groups. Total epididymal fat weight was reduced in MO‐fed rats. There was a significant positive correlation between adipose tissue weight and plasma free fatty acids. MO‐fed rats had lower plasma insulin levels. Insulin was directly correlated with plasma triacylglycerol and glucose, consistent with a hyperinsulinemic, insulin‐resistant state in CO‐and L‐fed rats, and a protective effect with MO feeding. In addition, insulin was directly correlated with adipose LPL. A negative relationship between soleus muscle LPL and insulin approached significance. Soleus muscle LPL was significantly inversely correlated with triacylglycerol. The data indicate that increased skeletal muscle LPL, in response to MO or a MO‐induced decrease in insulin, may contribute to the triacylglycerol‐lowering effects of fish oil. Decreased fat weight and adipose LPL and increased soleus muscle LPL and decreased plasma triacylglycerol suggest a shift from fat deposition to oxidation with MO feeding. The lack of response of hepatic lipase to MO feeding suggests that this enzyme does not contribute to the fish oil‐stimulated lowering of plasma triacyglycerolvia hepatic reuptake of very low density lipoproteins or other triacylglycerol‐rich lipoproteins.
Methyl‐branched octanoic acids as substrates for lipase‐catalyzed reactions
Authors: Sonnet Philip E. , Baillargeon Mary Welch 
Published: November 2006

AbstractHydrolyses of racemic methyl‐branched octanoic acid thiolesters are described using six commercial lipases as catalysts. Branching at positions 2, 4 and 5 greatly reduced activity; branching at the 3‐position virtually eliminated activity. The reactivities of the racemic branched thiolesters relative to the unbranched ester were very similar for each lipase preparation examined. In reactions involving configurationally pure 2‐methyloctanoic acids, the S‐enantiomer reacted faster both in esterification of aliphatic alcohols and in hydrolyses of aliphatic alcohol esters with all of the lipases examined. Stereobiases in hydrolyses of the octanoic acid esters branched at other positions were low and variable. In sharp contrast to the hydrolyses of the thiolesters of 2‐methyloctanoic acid, two aryl esters of 2‐methyloctanoic acid catalyzed byR. miehei lipase hydrolyzed with a bias for the R‐configuration. A view of the ester‐enzyme complex is offered, to explain the relative rates of reaction of the racemic esters.
A spectrophotometric assay for hydroperoxide lyase
Authors: Vick Brady A. 
Published: November 2006

AbstractSpectrophotometric assays for hydroperoxide lyase have traditionally measured the loss in absorption at 234 nm due to the disruption of conjugated diene in the fatty acid hydroperoxide. However, that assay does not distinguish between hydroperoxide lyase and hydroperoxide dehydrase activities, both of which cause a loss of conjugation in the substrate hydroperoxide. A new assay has been developed which is specific for hydroperoxide lyase. It is based on the ability of hydroperoxide lyase products, aldehydes and ω‐oxoacids, to serve as substrates for yeast alcohol dehydrogenase. Thus, the new hydroperoxide lyase assay is a coupled enzyme assay, which is conducted spectrophotometrically at 340 nm and measures the oxidation of nicotinamide adenenine dinucleotide, reduced form (NADH). In addition to its specificity for hydroperoxide lyase, the coupled assay allows higher concentrations of both fatty acid hydroperoxide substrate and crude enzyme extracts than the assay conducted at 234 nm.
Two novel phospholipid fatty acids from the caribbean spongeGeodia gibberosa
Authors: Carballelra Néstor M. , Rodriguez Jaime 
Published: November 2006

AbstractThe novel fatty acids (Z)‐6‐nonadecenoic acid (1) and (Z)‐17‐pentacosenoic acid (2) were characterized in the spongeGeodia gibberosa. These fatty acids were mainly found in phosphatidylethanolamine and phosphatidylcholine.