bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation and properties ofgem‐dichlorocyclopropane derivatives of long‐chain fatty esters
Authors: Lie Ken Jie Marcel S. F. , Wong C. F.
Published: November 2006

Methyl oleate (18∶1) and linoleate (18∶2) were readily transformed to the correspondinggem‐dichlorocyclopropane derivatives in high yield, using triethylbenzylammonium chloride as the phase‐transfer catalyst in the presence of aqueous NaOH and CHCl3. Reaction of dichlorocarbene with methyl 12‐hydroxystearate furnished methyl 12‐chlorostearate (49%) and 12‐O‐formylstearate (19%). The hydroxy group in methyl ricinoleate was protected (O‐tetrahydropyran‐2′‐yl) prior to dichlorocyclopropanation of the ethylenic bond. Removal of the protecting group allowed the hydroxy group to be converted to a chloride,O‐acetyl, azido orO‐formyl function. Treatment of methyl ricinoleate with thionyl chloride, followed by the reaction with dichlorocarbene gave the corresponding 12‐chloro‐dichlorocyclopropane derivative. The dichlorocyclopropane derivative of oleic acid was transformed to a C19 allenic fatty acid when treated witht‐butyl lithium. However, the remaining dichlorocyclopropane derivatives, containing an additional functional group in the alkyl chain, failed to yield the corresponding allenic derivatives. All derivatives were characterized by a combination of spectroscopic and chromatographic techniques, including infrared,1H nuclear magnetic resonance (NMR), and13C NMR spectroscopy.
Measurement of bile acid synthesis in man by release of14CO2 from [26‐14C]cholesterol: Comparison to isotope dilution and assessment of optimum reference cholesterol specific activity
Authors: Mitchell John C. , Stone Bradford G. , Duane William C.
Published: November 2006

Bile acid synthesis can be measured as release of14CO2 from [26‐14C]cholesterol divided by cholesterol specific activity, but this method has not been validated in human subjects. We made twelve comparisons of this CO2 method to standard isotope dilution in six normal subjects and found a mean discrepancy of 6%. Linear regression analysis of one value with respect to the other revealed a correlation coefficient of 0.83 (P<0.001), a Y‐intercept close to zero (−4.98) and a slope close to 1 (1.06), suggesting good correspondence between the two methods. To assess the potential for error arising from use of serum cholesterol to estimate specific activity of cholesterol used for bile acid synthesis, we compared synthesis measured using serum free cholesterol specific activity to that measured using bile cholesterol specific activity, which is known to be near isotopic equilibrium with the precursor pool used for bile acid synthesis. Synthesis calculated in these two ways differed by less than 10%. The data indicate that the CO2 method using either serum or bile cholesterol specific activity provides a valid estimate of bile acid synthesis in man.
Two novel naturally occurring α‐methoxy acids from the phospholipids of two caribbean sponges
Authors: Carballeira Néstor M. , Sepúlveda Juan A.
Published: November 2006

The novel (5Z)‐2‐methoxy‐5‐hexadecenoic acid (1) was identified in the phospholipids of the spongeTethya crypta while the also novel acid (6Z)‐2‐methoxy‐6‐hexadecenoic acid (2) was found in the phospholipids of the Caribbean spongeSpheciospongia cuspidifera. The methoxy‐fatty acids were mainly associated with phosphatidylethanolamine. The double bond positions were determined by gas chromatography/mass spectrometry on the corresponding dimethyl‐disulfide adducts and the double bond stereochemistry was ascertained by gas chromatography/Fourier transform infrared spectroscopy. The fatty acid composition of the two sponges is reported.
Occurrence of wax esters and 1‐O‐alkyl‐2,3‐diacylglycerols in goat epididymal sperm plasma membrane
Authors: Rana Ajay P. S. , Majumder Gopal C. , Misra Suniti , Ghosh Amitabha
Published: November 2006

Two unusual lipid classes were detected by thin‐layer chromatography in the neutral lipids derived from goat cauda‐epididymal sperm plasma membrane. The lipids were identified as wax esters and 1‐O‐alkyl‐2,3‐diacylglycerols based on chromatographic properties, identity of their hydrolysis products, and infrared/1H nuclear magnetic resonance spectral evidence. The membrane containedca. 3 and 5 μg/mg protein of wax esters and alkyldiacylglycerols, respectively. The relative proportions of wax esters and alkyldiacylglycerols in the total neutral lipids were 1.5% and 2.4%, respectively. The lipids contained fatty acids with chain lengths of C14 to C22. The major fatty acids of the wax esters were 14∶0, 16∶0, 16∶1ω7, 18∶0 and 18∶1ω9. The fatty acids in alkyldiacylglycerol were 16∶0, 18∶0, 22∶5ω3 and 22∶6ω3. Alkyldiacylglycerol was particularly rich in docosahexaenoic acid 22∶6ω3) representing 30% of the total fatty acids. The alcohols of wax ester were all saturated with C20–C29 carbon chains. The deacylated products derived from alkyldiacylglycerols were identified as hexadecyl, octadecyl and octadec‐9′‐enyl glycerol ethers.
Effects of lovastatin on hepatic fatty acid metabolism
Authors: Guzmán Manuel , Cortés Josefa P. , Castro José
Published: November 2006

Thein vitro andin vivo effects of lovastatin on fatty acid metabolism were studied in isolated rat hepatocytes. When addedin vitro to cell incubations, lovastatin stimulatedde novo fatty acid synthesis and acetyl‐CoA carboxylase activity, whereas fatty acid synthase, activity was unaffected. Lovastatin depressed palmitate, but not octanoate, oxidation. This may be attributed to the lovastatin‐induced increase, in intracellular malonyl‐CoA levels, as no concomitant changes of carnitine palmitoyltransferase I (CPT‐I) specific activity was detected. Lovastatin had no effect on the synthesis and secretion of triacylglycerols and phospholipids in the form of very low density lipoproteins (VLDL). When rats were fed a diet supplemented with 0.1% (w/w) lovastatin for one week, both acetyl‐CoA carboxylase activity andde novo fatty acid synthesis were reduced compared to pair‐fed controls, whereas fatty acid synthase activity was unaffected. Palmitate oxidation was enhanced in the lovastatin‐fed group. There was an increase in CPT‐I activity but no change in intracellular concentration of malonyl‐CoA. Lovastatin feeding and no significant effect either on the esterification of exogenous palmitic acid into both cellular and VLDL triacylglycerols and phospholipids or on hepatic lipid accumulation. Thein vitro andin vivo effects of lovastatin were not significantly different between periportal and perivenous hepatocytes. The results indicate that: (i) the administration of lovastatin increased the fatty acid‐oxidative capacity of the liver at the expense of its lipogenic capacity, (ii) the rate ofde novo cholesterol synthesis did not seem to be a limiting factor in the synthesis and secretion of VLDL and (iii) lovastatin produced opposite effects on hepatic fatty acid metabolismin vitro andin vivo.
Vitamin E deficiency in dogs does not alter preferential incorporation ofRRR‐α‐tocopherol compared withall rac‐α‐tocopherol into plasma
Authors: Traber Maret G. , Pillai Shreekumar R. , Kayden Herbert J. , Steiss Janet E.
Published: November 2006

The plasma and lipoprotein transport ofRRR andall rac‐α‐tocopherols, labeled with different amounts of deuterium [2R,4′R,8′R‐α‐[5‐C2H3]tocopheryl acetate (d3RRR‐α‐tocopheryl acetate] and 2RS, 4′RS, 8′RS‐α‐[5,7‐(C2H3)2]tocopheryl acetate (d5all rac‐α‐tocopheryl acetate), was studied in adult beagle dogs that had been fed a vitamin E‐deficient (−E; two dogs) or supplemented (+E; two dogs) diet for two years. We set out to test the hypothesis that the activity of the hepatic tocopherol binding protein (which is thought to preferentially incorporateRRR‐α‐tocopherol into the plasma) is up‐regulated by vitamin E deficiency. Labeled α‐tocopherols increased and decreased similarly in plasma of both −E and +E dogs. Irrespective of diet,d3RRR‐α‐tocopherol was preferentially secreted in plasma. Thus, vitamin E deficiency in dogs does not markedly increase the apparent function of the hepatic tocopherol binding protein. We also studied vitamin E transport in a German Shepherd dog with degenerative myelopathy (DM). Based on the coincident appearance ofd3RRR‐α‐tocopherol in plasma and chylomicrons, we suggest that the abnormality in DM may be associated with abnormal vitamin E transport resulting from an impaired function of the hepatic tocopherol binding protein.
Effect of maternal dietary arachidonic or linoleic acid on rat pup fatty acid profiles
Authors: Lien Eric L. , Boyle Fran G. , Yuhas Rebecca J. , Kuhlman Charles F.
Published: November 2006

Rapidly growing neonatal mammals accrete relatively large quantities of long chain (≥C20) polyunsaturated fatty acids (LCP) in membrane phospholipids. We have examined accumulation of ω6 LCP in suckling neonatal rat pups during the first 14 d of life when their dams received essential fatty acids in the form of triglycerides containing linoleic acid or arachidonic acid. Dietary levels of these fatty acids were either 1 or 5% of total dietary fatty acids. The fatty acid profile of pup stomach contents (composed solely of the dams' milk) and plasma lipids, as well as liver and brain phospholipids, were determined. Stomach linoleic and arachidonic acid levels reflected the diet of the dams. Pup plasma and liver arachidonic acid levels increased progressively from the group receiving 1% linoleic acid to 5% linoleic acid and from 1% arachidonic acid to 5% arachidonic acid. Interestingly, brain phosphatidylethanolamine and phosphatidylcholine arachidonic acid levels were more stable than plasma or liver levels. These results suggest that the brain may be capable of either selective transport of ω6 LCP or chain elongation/desaturation of linoleic acid. These data indicate that care must be exercised when adding LCP to infant formula since widely divergent accretion rates of arachidonic acid may occur in various tissues.
Abnormal plasma lipids of patients withRetinitis pigmentosa
Authors: Holman R. T. , Bibus D. M. , Jeffrey G. H. , Smethurst P. , Crofts J. W.
Published: November 2006

Retinitis pigmentosa (RP) is a hereditary retinal degeneration of unknown etiology, resulting in progressive night blindness, loss of peripheral vision, abnormal retinal pigmentation and reduced electroretinographic response. Docosahexaenoic acid (22∶6ω3) is found in high concentration in the rod outer segment membranes of the retina. Previous reports of low 22∶6ω3 in blood lipids or phospholipids in RP patients prompted us to evaluate the complete fatty acid (FA) profiles of plasma phospholipids (PL), cholesteryl esters, triglycerides (TG) and nonesterified fatty acids (NEFA) in ten patients with RP. In the PL fraction, we found significantly depressed levels of 22∶6ω3, 22∶5ω3, total ω3, 22∶5ω6, 22∶4ω6 and total ω6 polyunsaturated FA (PUFA), and elevated total saturated acids. Plasma TG showed normal levels of PUFA, normal total saturated FA and total monounsaturated FA. The NEFA fraction showed significant elevation in total saturated FA with depressed total ω6 PUFA. Evidence is accumulating that RP is associated with abnormal PUFA and lipid metabolism.
An improved method for the measurement of malondialdehyde in biological samples
Authors: Li Xiu‐Yan , Chow Ching K.
Published: November 2006

An 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

The 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

The 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

The 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

In 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

We 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

Previous 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

The 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

The 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

Quantities 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

Rat 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

To 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

Hydrolyses 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

Spectrophotometric 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

The 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.
Gradient ford‐glucose and linoleic acid uptake along the crypt‐villus axis of rabbit jejunal brush border membrane vesicles
Authors: Fingerote R. J. , Doring K. A. , Thomson A. B. R.
Published: November 2006

Glucose uptake into jejunal brush border membrane (BBM) varies along the crypt‐villus axis (CVA). In the present study, the question was addressed whether uptake of the essential long‐chain fatty acid linoleic acid also varies along the CVA. Using agitation techniques, five jejunal enterocyte fractions were sequentially isolated from female New Zealand white rabbits. A sixth and final fraction of lower‐villus/crypt cells was obtained by the scraping of the remaining jejunal mucosa. Cell fraction along the CVA was proven histologically, by noting decreasing alkaline phosphatase activities in sequentially isolated fractions, and by demonstrating [3H‐methyl]thymidine uptake mainly in the final fraction of the lower villus/crypt cells. BBM vesicles were prepared from the upper‐, mid‐ and lower‐villus/crypt enterocyte fractions, using differential centrifugation and divalent ion precipitation.d‐Glucose uptake into each fraction showed an Na+‐gradient dependent time‐course “overshoot” with linear uptake to 15 s and a subsequent decline to a steady‐state plateau. Varying D‐glucose concentrations from 50–1000 μM demonstrated saturation kinetics of uptake, with maximal transport rates (Vmax) and Michaelis affinity constants (Km) varying between fractions; the Km and Vmax were both lowest in the upper‐villus fraction. A linear relationship existed between linoleic acid concentration (25–200 μM) and uptake in each fraction. Linoleic acid uptake was equivalent in all fractions when expressed per mg protein, but when expressed in terms of the estimated minimal BBM, vesicle surface area uptake was greater in the upper‐ than in the lower‐villus/crypt fractions. Thus, BBM vesicle uptake of both linoleic acid and glucose vary along the crypt‐villus axis of the rabbit jejunum.
The effect of dietary fat level and quality on plasma lipoprotein lipids and plasma fatty acids in normocholesterolemic subjects
Authors: Sanders Kerrie , Johnson Leeann , O'Dea Kerin , Sinclair Andrew J.
Published: November 2006

This study examined the effect on the plasma lipids and plasma phospholipid and cholesteryl ester fatty acids of changing from a typical western diet to a very low fat (VLF) vegetarian diet containing one egg/day. The effect of the addition of saturated, monounsaturated or polyunsaturated fat (PUFA) to the VLF diet was also examined. Three groups of 10 subjects (6 women, 4 men) were fed the VLF diet (10% energy as fat) for two weeks, and then in the next two weeks the dietary fat in each group was increased by 10% energy/week using butter, olive oil or safflower oil. The fat replaced dietary carbohydrate. The VLF diet reduced both the low density lipoprotein (LDL)‐and high density lipoprotein (HDL)‐cholesterol levels; addition of the monounsaturated fats and PUFA increased the HDL‐cholesterol levels, whereas butter increased the cholesterol levels in both the LDL‐ and HDL‐fractions. The VLF diet led to significant reductions in the proportion of linoleic acid (18∶2ω6) and eicosapentaenoic acid (20∶5ω3) and to increases in palmitoleic (16∶1), eicosatrienoic (20∶3ω6) and arachidonic acids (20∶4ω6) in both phospholipids and cholesteryl esters. Addition of butter reversed the changes seen on the VLF diet, with the exception of 16∶1, which remained elevated. Addition of olive oil resulted in a significant rise in the proportion of 18∶1 and significant decreases in all ω3 PUFA except 22∶6 compared with the usual diet. The addition of safflower oil resulted in significant increases in 18∶2 and 20∶4ω6 and significant decreases in 18∶1, 20∶5ω3 and 22∶5ω3. These results indicate that the reduction of saturated fat content of the diet (<6% dietary energy), either by reducing the total fat content of the diet or by exchanging saturated fat with unsaturated fat, reduced the total plasma cholesterol levels by approximately 12% in normocholesterolemic subjects. Although the VLF vegetarian diet reduced both LDL‐ and HDL‐cholesterol levels, the long‐term effects of VLF diets are unlikely to be deteterious since populations which habitually consume these diets have low rates of coronary heart disease. The addition of safflower oil or olive oil to a VLF diet produced favorable changes in the lipoprotein lipid profile compared with the addition of butter. The VLF diets and diets rich in butter, olive oil or safflower oil had different effects on the 20 carbon eicosanoid precursor fatty acids in the plasma. This suggests that advice on plasma lipid lowering should also take into account the effect of the diet on the fatty acid profile of the plasma lipids.
Singlet oxygen quenching ability of naturally occurring carotenoids
Authors: Hirayama Osamu , Nakamura Kyoko , Hamada Syoko , Kobayasi Yoko
Published: November 2006

The singlet oxygen quenching ability of various naturally occurring carotenoids was examined by measuring toluidine blue‐sensitized photooxidation of linoleic acid. To assess quenching, the oxidation of linoleic acid was followed by measuring oxygen consumption and ultraviolet absorbance at 235 nm. We found that oxygen quenching increased as the number of conjugated double bonds in the carotenoids increased, but quenching varied with chain structure and functional groups. Acyclic carotenoids enhanced quenching more than did cyclic carotenoids. Conjugated keto groups and the presence of a cyclopentane ring stimulated quenching, while hydroxy, epoxy and methoxy groups showed lesser effects. The photosynthetic bacterial carotenoids, spirilloxanthin and rhodopin, were found to be most effective as quenchers, followed by the cayenne carotenoid, capsorbin.
Quantitative effects of dietary polyunsaturated fats on the composition of fatty acids in rat tissues
Authors: Lands William E. M. , Morris Anna , Libelt Bozena
Published: November 2006

A method combining data on fatty acid composition into subsets is used to illustrate general relative competitive selectivities in the metabolic and transport events that maintain fatty acid compositions in tissue lipids and to minimize differences among tissues or species in the amount of individual fatty acids. Fatty acid compositions of triglycerides and phospholipids in several tissues of the rat were maintained with simple relationships between the exogenous n−3 and n−6 dietary polyunsaturated fatty acids and the endogenous n−7 and n−9 types of fatty acid. The general pattern of fatty acids in triglycerides was similar for liver, plasma and adipose tissue, averaging about 30% as saturated acids, 67% as 16‐ and 18‐carbon unsaturated acids and only about 2% as 20‐ and 22‐carbon highly unsaturated acids. The tissues maintained a linear relationship between the amount of 18‐carbon polyunsaturated fatty acids in the diet and in the tissue triglycerides, with the proportionality constant for 18∶3n−3 being 60% of that for 18∶2n−6. The total phospholipids of liver, plasma and red blood cells maintained about 45% of the fatty acids in the form of saturated fatty acids and 20–30% as 20‐ and 22‐carbon highly unsaturated fatty acids irrespective of very different proportions of n−3, n−6 and n−9 types of fatty acids. In all three tissues, the 20‐carbon highly unsaturated fatty acids of the n−3, n−6 and n−9 type were maintained in a competitive hyperbolic relationship with apparent EC50 values for dietary 18∶2n−6 and 18∶3n−3 near 0.1% of dietary calories. The consistent quantitative relationships described in this study illustrate an underlying principle of competition among fatty acids for a limited number of esterification sites. This approach may be useful in predicting the influence of diet upon tissue levels of the substrates and antagonists of eicosanoid biosynthesis.
Fatty acid content of marine oil capsules
Authors: Chee Kew M. , Gong Jun Xian , Good Rees Deirdre M. , Meydanl Mohsen , Ausman Lynne , Johnson Julia , Siguel Edward N. , Schaefer Ernst J.
Published: November 2006

The use of dietary ω3 fatty acid capsules has been associated with a decrease in plasma triglyceride levels. In addition, populations consuming diets rich in fish appear to have a decreased incidence of cardiovascular disease. Eicosapentaenoic acid (EPA, 20∶5ω3) and docosahexaenoic acid (DHA, 22∶6ω3) are major fatty acids in fish oils. It is believed that fish oils exert their biolotic effect through these fatty acids. Many individuals are currently taking fish oil capsules to lower lipids, increase bleeding time, and possibly decrease cardiovascular risk. These capsules also have been classified as food additives with less stringent controls on content. We assessed the fatty acid, cholesterol, and vitamin A and E content of eight commercially available capcules along with cod liver oil. The content of EPA was found to range from 8.7–26.4% (wt%) with a mean of 17.3% (82.4% of labeled content), and that of DHA from 8.9–17.4% with a mean of 11.5% (90.0% of labeled content) as assessed by capillary column gas‐liquid chromatography. The mean content of the polyunsaturated ω3 fatty acids was 31.9%, and that of the ω6 fatty acids was 1.4%. The content of saturated fatty acids was 32,0%, and that of monounsaturated fatty acids was 25.1%. Cholesterol content was low, with a range of 0.7–8.3 mg/g, the α‐tocopherol range was 0.62–2.24 mg/g, and the range of retinyl esters was 0.4–298.4 μg/g. Cod liver oil had substantially more retinyl esters (2450.1 μg/g) than did fish oil capsules. Our data serve as an independent guide to fish oil capsule fatty acid content upon single lot analysis, and indicate that these capsules contain as much saturated fat as they contain ω3 fatty acids.
Effect of increasing the level of ω‐3 fatty acids on rat skeletal muscle sarcoplasmic reticulum
Authors: Stubbs C. D. , Kisielewski A. E.
Published: November 2006

The effect of dietary supplementation with fish oil as compared to corn oil on the lipid dynamics and calcium ATPase activity of rat skeletal sarcoplasmic reticulum was examined. After four‐week supplementation with fish oil, the levels of eicosapentaenoic (20∶5ω3), docosapentaenoic (22∶5ω3) and docosahexaenoic (22∶6ω3) acids in the total lipids were 5.3, 5.5 and 28.1% of the total fatty acids, respectively. In contrast, with corn oil only 22∶6 was found (8.9%). The level of these fatty acids in phosphatidylethanolamine from the membranes of animals fed fish oil was 4.2 (20∶5), 5.4 (22∶5) and 49.1% (22∶6); and for phosphatidylcholine it was 5.4 (20∶5), 4.6 (22∶5) and 17.4% (22∶6). Again, in corn oil fed animals, only 22∶6 was found in appreciable amounts, namely 28.3% in phosphatidylethanolamine and 1.8% in phosphatidylcholine. The steady state fluorescence anisotropy of 1,6‐diphenyl‐1,3,5‐hexatriene (DPH) was used to assess lipid order and was found to be only slightly less for membranes from animals supplemented with fish oil (0.120) as compared to those supplemented with corn oil (0.124). The calcium ATPase was found to be unaffected by supplementation consistent with the observed modest changes in lipid order as well as with suggestions that the enzyme is relatively insensitive to the level of unsaturation. It could be argued that if large increases in fatty acyl polyunsaturation in mammalian cell membranes would lead to marked alterations in bulk membrane lipid motional properties, this may not be in the interest of preserving physiological function. The complex mixture of phospholipid molecular species present in natural membranes may buffer against this by a type of passive adaptation, without the expenditure of metabolic energy, thus providing a homeoviscous environment able to optimally support membrane protein function.
Comparison of cell membrane phospholipid fatty acids in five rat strains fed four test diets
Authors: Cleland Leslie G. , Gibson Robert A. , Hawkes Joanna S. , James Michael J.
Published: November 2006

The fatty acid composition of phospholipids in peritoneal exudate cells and spleen cells was assessed in five rat strains fed four test diets of differing fatty acid composition. Distinctive patterns of fatty acids were seen in the total phospholipid preparations in both cell types in response to the diets which contained either olive, sunflower, linseed or fish oil. In general, similar fatty acid profiles were seen in each of the rat strains fed the same diet with the only evidence of possible genetic (strain) variation being a relative deficiency of Δ4 desaturase in Dark Agouti rats.
Lipoprotein lipase and hepatic lipase in Wistar and Sprague‐Dawley rat tissues. Differences in the effects of gender and fasting
Authors: Galan Xavier , Llobera Miquel , Ramírez Ignasi
Published: November 2006

To evaluate the effects of strain, gender and fasting in the regulation of lipoprotein lipase (LPL) and hepatic lipase (HL) activities were measured in tissues of male and female Wistar and Sprague‐Dawley rats after feeding or a 24‐h starvation period. It is noteworthy that an effect of gender on LPL activity was observed in Wistar, but not in Sprague‐Dawley rats, not in the basal (fed) activity in several tissues, such as white and brown adipose tissues, heart, and brain, but also in response to fasting which affected LPL activity in brown adipose tissue, heat and lung of female but not of male Wistar rats. By contrast, HL activity in liver, plasma and adrenals of Sprague‐Dawley rats was higher in females than in males. No effect of gender on HL activity was observed in Wistar rats. Our results indicate that differences exist between Wistar and Sprague‐Dawley rats in the regulation of both LPL and HL. Some of the contradictory results found in the literature may be explained by the differences between rat strains and gender, as well as differences in the nutritional status of the animals.