bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipoprotein lipid and protein synthesis in experimental nephrosis and plasmapheresis: II. Perfused rat liver
Authors: Brenner Talma , Shafrir Eleazar
Published: November 2006

Livers from rats with experimental hypoproteinemia induced by aminonucleoside‐nephrosis or plasmapheresis were perfused with a [14C]‐labeled amino acid mixture at physiological concentration. Compared to control rats, a significantly increased incorporation of the amino acid label was found in the apolipoproteins of the ultracentrifugally separated very low and high density lipoproteins (VLDL, HDL), and into albumin secreted into the perfusate. However, no increase in the amino acid‐derived label was detected in VLDL‐ or HDL‐borne lipids in nephrosis or plasmapheresis. Perfusion with U‐[14C] leucine as a lipogenesis precursor at >10 times higher than physiological concentration resulted in 5‐fold increase in the label incorporation into perfusate proteins in nephrosis but only in a slightly significant increase in perfusate lipids. In contrast, the incorporation of a preformed fatty acid, 9,10‐[3H] oleate into VLDL and HDL lipids increased 3‐ to 4‐fold in nephrosis. Both with leucine and oleate as precursors, the increments in the label appearing in perfusate proteins or lipids, respectively, were markedly greater than the increases in hepatic tissue proteins or lipids. The results indicate that amino acids are preferentially directed by the liver into the synthesis of circulating apolipoproteins and albumin in hypoproteinemia and do not seem to constitute an important precursor of the lipoprotein lipids. The increased production of apolipoproteins is associated with an increased incorporation of preformed fatty acids into lipoprotein lipids in addition to the previously reported stimulation of hepatic de novo lipid synthesis from precursors other than amino acids.
Analysis and physiologic significance of cholesterol epoxide in animal tissues
Authors: Black Homer S.
Published: November 2006

The presence of 5α,6α‐epoxy‐cholestan‐3β‐ol, an oxidation product of cholesterol, has been demonstrated in a variety of animal tissues. No definitive biologic role for this sterol has been forthcoming, although the physiologic implications of its occurrence are many. The presence of the epoxide in ultraviolet (UV)‐irradiated skin was detected by a combination of thin layer chromatography (TLC) and gas liquid radiochromatographic (radio‐GLC) techniques in 1971 and led to the suggestion that it might be responsible for the carcinogenic properties of UV. Subsequently, in vivo levels of this sterol in the skin of UV‐irradiated animals were quantitated by radio‐GLC after TLC separation and preparation of the radiolabeled acetate ester. Presence of the compound in mouse liver was detected by GLC of the trimethylsilyl (TMS) ether and confirmed by mass spectrometry (MS). In all cases, however, in vivo quantitations were complicated by substrate induction of sterol epoxide hydrase, an enzyme that hydrates the epoxide to form cholestan‐3β,5α,6β‐triol (triol). Consequently, the relationship of the sterol epoxide to UV‐carcinogenesis is as yet unclear and recent studies suggest that if this sterol is involved, then further metabolism of the compound must be required. A practical means of examining the metabolites of the epoxide was developed, employing radio‐TLC scanning. Using this procedure, the relationships of substrate concentration, time of reaction and pH optimum to reaction rate were determined. Although in short term in vitro incubations of liver homogenates the bulk of epoxide is hydrated to triol, several other metabolites are detectable by TLC autoradiography. Even though the case for direct involvement of cholesterol epoxide in the etiology of carcinogenesis or other diseases is equivocal, the epoxide or its metabolites may yet prove valuable as a diagnostic aid in revealing abnormal function associated with certain diseases.
The analysis of urinary hormonal steroids
Authors: Vestergaard Per
Published: November 2006

A survey is given of current trends in the assay of urinary hormonal steroids. Both group assay methodology and assays for single urinary steroids are reviewed as are semi‐automated and automated procedures and high‐resolution and high‐capacity techniques, as applied to the profile analysis of urinary steroid hormones.
Utilization of polyunsaturated fatty acids by human diploid cells aging in vitro
Authors: Lynch Robert D.
Published: November 2006

Cultures of human diploid cell strain IMR‐90 were supplemented with γ‐linolenic acid, 18∶3ω6, by constant infusion over 72 hr. Cell growth was twice that observed when the same amount of fatty acid was supplied as a single dose at the start of a 72‐hr incubation. Using the infusion method, growth of cells receiving monoenoic or polyenoic fatty acids was compared. The age of these cells in vitro was measured in terms of the culture mean population doubling level (PDL). Population doubling level refers to the mean number of doublings elapsed since establishment of a primary culture. At PDL from 24–53, the growth of cells from cultures supplemented with oleic acid was similar to that of noninfused cultures. Gamma linolenic acid, 18∶3ω6, and to greater extent arachidonic acid, 20∶4ω6, however, caused suppression of cell multiplication at PDL≤32, but not at PDL≥44. The polyunsaturated fatty acid (PUFA) levels in cell phospholipids were reduced by exogenous oleic acid to half that of nonsupplemented cells at all PDL tested. Conversely, the PUFA levels in phospholipids were elevated by a factor of 1.6 at all PDL when cultures were infused with 18∶3ω6. Triglyceride levels at the end of 72 hr were similar, but much higher than the controls, regardless of the fatty acid supplied. Growth inhibition, modification of phospholipid acyl group content and triglyceride levels were not appreciably affected when the amount of monoenoic or polyenoic fatty acid infused into the cultures was doubled. The elongation of 18∶3, as well as the distribution of 18∶3 and its elongation products, between triglyceride and phospholipid, was dependent on whether the 18∶3 was of the ω3 or ω6 family.
Changes in host animal plasma lipids during hepatoma growth
Authors: Matocha Martha , Wood Randall
Published: November 2006

The concentrations of the major neutral lipid and phospholipid classes in the plasma of rats bearing hepatoma 7288CTC were determined at various times after transplantation. The fatty acid composition of each lipid class was also analyzed quantitatively as tumor growth progressed. Generally, most lipid classes exhibited a slight decrease between the third and sixth day after transplantation, returned to near normal levels by the 15th day, increased dramatically and peaked between the 24th and 27th days before plummeting sharply. At peak concentrations, triglycerides were increased 5 times the normal levels, whereas cholesterol, cholesteryl esters and phosphatidylcholines were increased 3‐fold. The percentage of hexadecenoates decreased in all lipid classes as tumor growth progressed and generally, stearate levels increased. In addition to monounsaturated fatty acids, lysophosphatidylcholines and phosphatidylcholines showed relatively large decreases in the percentages of polyunsaturated fatty acids with increased tumor growth. These results indicate that hepatoma 7288CTC can cause perturbation of host animal plasma lipids in the early stages of growth which precedes the massive hyperlipidemia. The interpretation of these results suggests that the early changes in plasma lipids may result from alterations in the normal lipid metabolism of the host, and the hyperlipidemia that develops later may result from the mobilization of lipids to compensate for the altered metabolism.
Lecithin influence on hyperlipemia in rhesus monkeys
Authors: Wong E. K. , Nicolosi R. J. , Low P. A. , Herd J. A. , Hayes K. C.
Published: November 2006

Previous studies in humans have shown that the ingestion of lecithin can alter plasma cholesterol and triglyceride concentrations by mechanism(s) that remain to be elucidated. To further explore this response to lecithin, hyperlipemic rhesus monkeys were selected from a group of animals fed a semipurified diet containing corn oil, casein, sucrose and cholesterol (120 mg/100 Kcal) for 10 years. Soybean lecithin (92% phosphatidylcholine) was supplemented in the diet (0.5 g/100 Kcal) of these monkeys. Measurements of plasma cholesterol, triglycerides and phospholipid were made prior to, during and following 7 wk of lecithin supplementation. In addition, determinations of triglyceride secretion rates following administration of Triton WR1339, triglyceride clearance after intravenous infusion of Intralipid® and plasma lecithin:cholesterol acyl transferase enzyme (LCAT) activity were assessed at the same time intervals. As in other studies, manipulation of lecithin intake elicited a highly variable response, but significant changes were observed in plasma cholesterol and triglycerides as a consequence of supplementing or removing lecithin from the diet. Lecithin had no influence on the absolute plasma phospholipid level or LCAT activity. However, lecithin significantly reduced total lipids, increased the relative concentration of phospholipid and tended to increase the phospholipid/free cholesterol (PL/FC) concentration. While lecithin did not significantly affect triglyceride secretion rates, all animals were able to clear Intralipid® (triglyceride) more efficiently while fed lecithin. These data are interpreted to mean that the reduction in plasma lipids associated with lecithin ingestion may have been mediated via enhanced clearance of lipids transported in lipoproteins of lower density, whereas the rebound following lecithin removal reflected reduced clearance of these lipids.
Effect of colestipol on sterol metabolism in the rat
Authors: Takahashi Makoto , Sarwal Amar N. , Raicht Robert F. , Cohen Bertram I.
Published: November 2006

Sterol metabolism studies using isotopic and chromatographic techniques were performed on rats fed diets supplemented with colestipol (Upjohn). Compared to controls, colestipol altered sterol metabolism dramatically. Bile acid output increased from 7.0 mg/day to 12.2 mg/day (0.42% colestipol) and 39.6 mg/day (1.67% colestipol). Daily fecal neutral sterol output and daily endogenous neutral sterol output increased 36% and 55%, respectively, on the 1.67% colestipol diet. Cholesterol absorption was reduced by colestipol feeding. Cholesterol balance increased dramatically with 1.67% colestipol administration (43.5 mg/day vs −1.0 mg/day in controls). Colestipol exerts its effect by binding bile acids and by bile acid depletion interfering with cholesterol absorption.
Carotene in bovine milk fat globules: Observations on origin and high content in tissue mitochondria
Authors: Patton Stuart , Kelly John J. , Keenan Thomas W.
Published: November 2006

The location and origin of carotenoids in bovine milk fat globules was investigated using spectral absorption of lipid solutions at 461 nm to quantitate carotene. Release of membrane from globules as a result of churning to butter or by freezing and thawing of the globules yielded membrane preparations which were devoid of carotene. Globule cores from these procedures exhibited carotene concentrations comparable to those in total milk lipids. Fractionation of lactating bovine tissue and analysis of lipid extracts revealed that the intracellular fat droplets have carotene concentrations approximating those of secreted blobules. However, intracellular membranes of the tissue, particularly the mitochondria, are much richer in carotenoids than formative or secreted fat globules. The evidence indicates that bovine milk fat globules acquire carotene during their formation in the cell, but that some minor fraction of the total carotene may be extracted from the enveloping secretory membrane. Mean carotene values (μg/g of lipid) for fractions from three samples of lactating tissue were: whole tissue 47, mitochondria 461, microsomes 69, cytosol 67, fat droplets 8, milk 9. One tissue analysis indicated that Golgi membranes contain somewhat more carotene than do microsomes.
The effect of oral contraceptives on mononuclear cell cholesteryl ester hydrolase activity
Authors: Hagemenas F. C. , Yatsu F. M. , Manaugh L. C.
Published: November 2006

The influence of sex steroids on mononuclear cell cholesteryl ester hydrolase (CEH) activity in premenopausal women and women on combined estrogen‐progestin oral contraceptives has been studied. In addition, plasma and mononuclear cell cholesterol and esters were measured along with plasma estrogen and progesterone levels. Mononuclear cell CEH activity in control women is highest on Day 20 of their menstrual cycle. The control women had significantly higher CEH activities than women on oral contraceptives. Plasma esters were higher in the oral contraceptive group. However, in mononuclear cells free cholesterol but not cholesteryl esters were higher in women on oral contraceptives.
Sterols of scallop. III. Characterization of some C‐24 epimeric sterols by high resolution (220 MHz) nuclear magnetic resonance spectroscopy
Authors: Khalil M. W. , Idler D. R. , Patterson G. W.
Published: November 2006

Alkyl sterols epimeric at C‐24 isolated from the Atlantic scallop,Placopecten magellanicus, were analyzed by high resolution (220 MHz) nuclear magnetic resonance spectrometry, and their spectra compared with authentic samples. This technique was used to assign absolute stereochemistry in epimeric mixtures of 24 R and S 24‐methylcholest‐5‐en‐3β‐ol, (22E)‐24‐methylcholesta‐5,22‐dien‐3β‐ol and 24‐ethylcholest‐5‐en‐3β‐ol. It also allowed a semiquantitative estimate of the R/S isomers present in the mixture.
Polar lipids ofMacrophomina phaseolina
Authors: Wassef Momtaz K. , Ammon Vernon , Wyllie T. D.
Published: November 2006

Macrophomina phaseolina was grown on a defined medium at three different carbon/nitrogen ratios. The lipids of the mycelia and the sclerotia were extracted; fractionated into polarity groups; and separated by thin layer, column, and gas liquid chromatographies. Sclerotia contained higher levels of neutral lipids and lower amounts of polar lipids than mycelia. The neutral lipid content of sclerotia increased, up to 77% of total lipids, and phospholipids decreased as carbon/nitrogen ratio increased from 10 to 320. The glycolipid content was not altered significantly by changes in carbon/nitrogen ratios. Although cardiolipin could not be detected in sclerotial polar lipids, both sclerotia and mycelia contained similar phospholipid profiles with major quantitative differences. Phosphatidic acid and phosphatidyl glycerol were major components of sclerotia, whereas phosphatidyl ethanolamine and phosphatidyl inositol were the major phosphatides of mycelia. Phosphatidyl choline was present in both mycelia and sclerotia. The fatty acid distribution did not show any particular pattern of saturation or unsaturation due to differences in carbon/nitrogen ratio. However, mycelial lipids tended to contain C24∶1, C18∶3, and C22∶1 as major fatty acids, whereas the major fatty acids in sclerotial lipids were C18∶2, C18∶1, C22∶1, C20∶0, and C16∶1. Saturated fatty acids were present in lesser concentrations.
Hepatoma, host liver, and normal rat liver neutral lipids as affected by diet
Authors: Wood Randall , Falch John , Wiegand Rex D.
Published: November 2006

Groups of normal and hepatoma (7288CTC) bearing rats were maintained on normal chow and fat‐free diets for 4 weeks. Normal liver, host liver, and hepatoma neutral lipids were examined in detail and compared. Water content, unaffected by diet was: hepatoma, 82%; host liver, 71%; and normal liver, 67%. The fat‐free diet had no effect upon the hepatoma neutral lipids but elevated the triglyceride level in normal and host liver, shifted the triglyceride carbon number distribution to lower mol wt, and elevated the percentage of monoenoic acids in triglycerides and cholesteryl esters. Host triglyceride concentrations were ca. half, and cholesterol levels were reduced moderately relative to normal liver values. Hepatoma cholesterol levels were higher and triglyceride concentrations lower than normal and host liver values. Hepatoma triglycerides differed dramatically from liver and were characterized by increased concentrations of high mol wt species and a fivefold increase in the percentage of C‐20 and C‐22 fatty acids. The percentage of C‐20 and C‐22 fatty acids in hepatoma cholesteryl esters also increased ca. fivefold relative to liver. The data indicate that the systems that regulate triglyceride and cholesteryl ester fatty acid composition in liver do not control the compositions of these lipid classes in this hepatoma. The unchanged high level of essential fatty acids in the hepatoma lipids from the fat‐free fed animals demonstrates the hepatoma's ability to absorb and conserve specific fatty acids.
Further studies on sphingolipids in wheat grain
Authors: Fujino Yasuhiko , Ohnishi Masao , Ito Seisuke
Published: November 2006

The principal molecular species of sphingolipids in wheat grain were confirmed to beN‐2′‐hydroxylignoceroyl‐4‐hydroxysphinganine for ceramide, and 1‐O‐β‐glucosyl‐, 1‐O‐[β‐mannosyl(1→4)‐O‐β‐glucosyl]‐, 1‐O‐[β‐mannosyl(1→4)‐O‐β‐mannosyl(1→4)‐O‐β‐glucosyl]‐and 1‐O[β‐mannosyl(1→4)‐O‐β‐mannosyl(1→4)‐O‐β‐mannosyl(1→4)‐O‐β‐glucosyl]‐N‐2′‐hydroxypalmitoyl (or hydroxyarachidoyl)‐cis‐8‐sphingenine for mono‐, di‐, tri‐ and tetraglycosylceramide, respectively. A novel glycolipid, cellobiosylceramide, was found as the minor diglycosylceramide; the major species was characterized to be 1‐O‐[β‐glucosyl(1→4)‐O‐β‐glucosyl]‐N‐2′‐hydroxypalmitoyl (or hydroxyarachidoyl)‐cis‐8‐sphingenine. It was observed in these sphingolipids that the dihydroxy bases were combined mainly with C16 and C20 acids, whereas the trihydroxy bases combined mostly with acids of chain length of 20 or more.
New long‐chain hydroxy acids fromGrevillea decora
Authors: Kleiman R. , Wolf R. B. , Plattner R. D.
Published: November 2006

In addition to the ω‐5 olefinic acids found in otherGrevillea species, about 10% of the acyl groups ofG. decora seed oil contain a hydroxy group and an ω‐5 double bond. The chainlengths of these acids are from C22 to C30, with the largest concentration at the C26 and C28 chainlengths. The hydroxy group is located on odd carbons from carbon‐5 through carbon‐13. These acids previously were unknown in nature. The most abundant of these are 7‐hydroxy‐cis‐17‐docosenoic, 7‐hydroxy‐cis‐19‐tetracosenoic, 9‐hydroxy‐cis‐19‐tetracosenoic, 9‐hydroxy‐cis‐21‐hexacosenoic, 11‐hydroxy‐cis‐21‐hexacosenoic, and 13‐hydroxy‐cis‐23‐octacosenoic acids. The oil also contains the largest known concentration of the unoxygenated C26 and C28 ω‐5 monoenes.
Action of cobra venom phospholipase A2 on large unilamellar vesicles: Comparison with small unilamellar vesicles and multibilayers
Authors: Kensil Charlotte Read , Dennis Edward A.
Published: November 2006

Phospholipase A2 (Naja naja naja) catalyzes the hydrolysis of dipalmitoyl phosphatidylcholine in small unilamellar vesicles (SUVs) with a faster initial rate than in large unilamellar vesicles (LUVs) and multilamellar vesicles (MLVs). For the SUVs, the hydrolysis was initially faster for gel phase than liquid crystalline phase phospholipid. For both LUVs and MLVs, hydrolysis was low except in a small temperature range around the thermotropic phase transition of the phospholipid. In this temperature range, the reaction time course of phospholipase action on dipalmitoyl phosphatidylcholine in LUVs and MLVs included a lag period. With SUVs, a lag period also was observed above the phase transition temperature, but it was not observed below it.
Dealkylation of various 14‐alkylsterols by the nematodeCaenorhabditis elegans
Authors: Lozano Ruben , Lusby William R. , Chitwood David J. , Svoboda James A.
Published: November 2006

The metabolism of 4 dietary 24‐alkylsterols was investigated in the free‐living nematodeCaenorhabditis elegans. The major unesterified sterols ofC. elegans in media supplemented with either campesterol, 22‐dihydrobrassicasterol or stigmasterol included cholesta‐5,7‐dienol, cholesterol, cholest‐7‐enol, and 4α‐methylcholest‐8(14)‐enol. Dietary stigmastanol yielded cholest‐7‐enol, cholestanol, cholest‐8(14)‐enol, and 4α‐methylcholest‐8(14)‐enol as major unesterified sterols. Esterified sterols comprised less than 22% of the total sterol. Removal of a C‐24 ethyl substituent of sterols was neither hindered by the presence of a Δ22‐bond in the sterol side chain nor was it depedent on unsaturation in ring B of the steroid nucleus.C. elegans reduced a Δ22‐bond during its metabolism of stigmasterol; it did not introduce a Δ22‐bond during stigmastanol metabolism.C. elegans was capable of removing a C‐24 methyl substituent regardless of its stereochemical orientation. Metabolic processes involving the steroid ring system of cholesterol (C‐7 dehydrogenation, Δ5‐bond, 4α‐methylation, Δ8(14)‐isomerization inC. elegans were not hindered by the presence of a 24‐methyl group; various 24‐methylsterol metabolites from campesterol were detected, mostly 24‐methylcholesta‐5,7‐dienol. In contrast, no 24‐ethylsterol metabolites from the dietary ethylsterols were found. More dietary 24‐methylsterol remained unmetabolized than did dietary 24‐ethylsterol. A 24α‐ethyl group and a 24β‐methyl group were dealkylated to a greater extent byC. elegans than was a 24α‐methyl group, perhaps reflecting the substrate specificity of the dealkylation enzyme system, or suggesting different enzymes altogether.
Mass spectra of TMS esters of deuterated decanoic acids and of TMS ethers of deuterated decanols
Authors: Tulloch A. P.
Published: November 2006

Mass spectra of trimethylsilyl esters of nine specifically deuterated decanoic acids and of trimethylsilyl ethers of the corresponding deuterated decanols and of tri[2H3] methylsilyl derivatives of most of the acids and of decanol have been measured. The fragmentation patterns have been used to examine the formation of ions m/z 117, 129, 131, 132, 145, 159, 171, 185 and 201 in the spectrum of the TMS ester of decanoic acid. Mechanisms of breakdown of one ion to another have been proposed. Similarities and differences in ion formation between spectra of TMS esters and methyl esters have been examined. It has been shown that ion m/z 132 is produced by the McLafferty rearrangement and that ion m/z 117 is formed from it by loss of a silyl methyl group. Ion m/z 145 is formed by hydrogen transfer from C‐5, C‐6 or C‐7 to the carbonyl oxygen and γ‐cleavage. Ion m/z 129 is formed from ion m/z 145 by loss of the previously transferred hydrogen and a silyl methyl group. A mechanism of formation of ions m/z 115, 129, 143 and 157, which contained only one silyl methyl group, observed in the mass spectrum of the TMS ether of decanol, has been proposed. Ions in spectra of the derivatives can be used to locate the position of deuterium, or other substituents, at a number of the carbons of decanoic acid or decanol.
Effect of brominated vegetable oils on heart lipid metabolism
Authors: Lombardo Yolanda B. , Chicco Adriana , Basílico María Z. , Bernal Claudio , Gutman Raul
Published: November 2006

Normal rats fed for 105 days on an experimental diet made up of standard laboratory chow supplemented with 0.5% of a mixture of brominated sunflower‐olive oil (BVO) developed a significant increase in the triacylglycerol content of the heart, liver and soleus muscle compared to controls. In addition, BVO‐treated rats had a decrease in plasma levels of triacylglycerol and total and HDL cholesterol. Plasma fatty acid levels and plasma post‐heparin lipolytic activities, such as H‐TGL, LPL, T‐TGL and MGH were similar to those of control animals fed the standard chow alone.

Heart PDHa (active portion of pyruvate dehydrogenase) was dramatically decreased in the BVO‐fed rats. A faster rate of spontaneous lipolysis was recorded in the isolated perfused preparation of hearts from the experimental animals. The addition of 10−7 M of glucagon to the perfusate, however, revealed a lipolytic effect comparable to the one observed in the control rats. In summary, our findings of normal fatty acids and low triacylglycerol plasma levels associated with normal activities of the various PHLA (post‐heparin lipolytic activity) enzymes suggest that accumulation of triacylglycerol in heart muscle may not be explained essentially in terms of an elevated uptake and/or increased delivery of plasma fatty acids or plasma triacylglycerol. A decreased in situ catabolism of tissue triacylglycerol also appears unlikely because the spontaneous as well as the glucagon induced lipolysis in the heart both were found to be unimpaired.

Our results suggest that the mechanisms involved in the toxicologic effects of a BVO diet on heart lipid metabolism could be exerted mainly at the level of triacylglycerol biosynthesis rather than a derangement in some known step of their catabolic pathway. Additional studies are necessary to clarify this matter.
Fatty acids of sphingomyelin from amniotic fluid of normal and diabetic pregnancies
Authors: Kokatnur Mohan , Brooks Vicki , Plauche Warren C.
Published: November 2006

Amniotic fluid collected from 14 normal and 11 diabetic patients was analyzed for phospholipids, and separated sphingomyelin and lecithin fractions were further studied for their fatty acid composition by gas liquid chromatography. Notable differences in percent fatty acid composition of sphingomyelin were observed for palmitic (16∶0; diabetic < normal), oleic (18∶1; diabetic > normal), behenic (22∶0; diabetic < normal) and arachidic acid (20∶0; absent in diabetics) in the specimens studied. Notable differences were not observed in fatty acids from lecithin fraction. Fatty acid composition of sphingomyelin from amniotic fluid is similar to fatty acid distribution in sphingomyelin from serum and erythrocyte and suggests maternal origin of the lipid.
Inhibition of C28 and C29 phytosterol metabolism by N, N‐dimethyldodecanamine in the nematodecaenorhabditis elegans
Authors: Lozano Ruben , Lusby William R. , Chitwood David J. , Thompson Malcolm J. , Svoboda James A.
Published: November 2006

Effects on the metabolism of campesterol and stigmasterol inCaenorhabditis elegans were investigated using N,N‐dimethyldodecanamine, a known inhibitor of growth, reproduction and the Δ24‐sterol reductase of this nematode. 7‐Dehydrocholesterol was the predominant sterol (51%) ofC. elegans grown in stigmasterol‐supplemented media, whereas addition of 25 ppm amine resulted in a large decrease in the relative percentage of 7‐dehydrocholesterol (23%) and the accumulation of a substantial proportion (33%) of Δ24‐sterols (e.g., cholesta‐5,7,24‐trienol) and Δ22,24‐sterols (e.g., cholesta‐5,7,22, 24‐tetraenol) but yielded no Δ22‐sterols. Dealkylation of stigmasterol byC. elegans proceeded in the presence of the Δ22‐bond; reduction of the Δ22‐bond occurred prior to Δ24‐reduction. Addition of 25 ppm amine to campesterol‐supplemented media altered the sterol composition ofC. elegans by increasing the percentage of unmetabolized dietary campesterol from 39 to 60%, decreasing the percentage of 7‐dehydrocholesterol from 26 to 12%, and causing the accumulation of several Δ24‐sterols (6%).C. elegans also was shown to be capable of dealkylating a Δ24(28)‐sterol as it converted 24‐methyl‐enecholesterol to mostly 7‐dehydrocholesterol. The proposed role of 24‐methylenecholesterol as an intermediate between campesterol and 7‐dehydrocholesterol was supported by the results.
High performance liquid chromatographic separation of stereoisomeric bile acids as their UV‐sensitive esters
Authors: Iida Takashi , Ohnuki Yasuo , Chang Frederic C. , Goto Junichi , Nambara Toshio
Published: November 2006

High performance liquid chromatographic separation of a series of mono‐, di‐ and trihydroxylated 5β‐cholanic acids which differ only in position and configuration of hydroxyl groups at positions C‐3, C‐7 and/or C‐12, is reported. The C‐24 free acids were derivatized to four different classes of UV‐sensitive esters, i.e.,p‐bromophenacyl (BP),m‐methoxyphenacyl (MP), 4‐nitrophthalimidemethyl (NPM) and 9‐anthrylmethyl (AM) esters, and chromatographed on two, variants of C18 reversed‐phase columns (Nova‐Pak C18 and Zorbax ODS) with methanol‐water systems as mobile phase. Separation efficiency and elution order of some isomeric pairs were influenced by both the structure of the C‐24 ester groups and the nature of the columns used. Excellent chromatographic properties were found for those derivatives, particularly for the NPM esters.
Lipid composition of different areas of murine brain: Effects of lipid extraction procedures
Authors: Katyal S. L. , Barilaro Linda , Hanin Israel
Published: November 2006

The effects of various chemical extraction procedures on the determination of lipid composition of rat and mouse brain have been investigated. Tissue extractions with formic acid/acetone or perchloric acid both resulted in significant losses of total phospholipids and cholesterol. Perchloric acid extraction also degraded, almost quantitatively, ethanolamine plasmalogens to lysophosphatidylethanolamine. Our findings have thus demonstrated that conventional procedures used for extraction of brain tissue for analysis of choline and acetylcholine content cannot also be used for concurrent/simultaneous extraction of phospholipids and cholesterol from the same tissue.
Dietary fats containing concentrates ofcis ortrans octadecenoates and the patterns of polyunsaturated fatty acids of liver phosphatidylcholine and phosphatidylethanolamine
Authors: Lawson Larry D. , Hill Eldon G. , Holman Ralph T.
Published: November 2006

The effects of the mixedcis‐ 18∶1 isomers and mixedtrans‐18∶1 isomers present in partially hydrogenated soybean oil (PHSO) upon the patterns of polyunsaturated fatty acids (PUFA) in liver phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were studied in rats fed concentrates ofcis‐ 18∶1 ortrans‐ 18∶1 isomers isolated as triacylglycerides from PHSO. Thecis‐ 18∶1 andtrans‐ 18∶1 concentrates were fed at levels equal to those present in PHSO fed at 17.9% of the diet. All diets contained the required amounts of both linoleic and linolenic acids. Thetrans‐ 18∶1 concentrate was found to suppress the levels of 20∶4ω6 and 20∶3ω9, and to increase the levels of 18∶2ω6 and 20∶5ω3 in PC and PE. Thecis‐ 18∶1 concentrate suppressed 20∶4ω6 in PC, 20∶5ω3 in PC and PE, and 18∶2ω6 was more effective than thetrans concentrate in suppressing 22∶6ω3. Thetrans‐ 18∶1 concentrate was more effective in suppressing 20∶4ω6. Thetrans‐18∶ isomers appear to modify PUFA metabolism by inhibition of PUFA synthesis, whereas thecis‐ 18∶1isomers appear to compete with 2‐position fatty acyl transfer and to inhibit ω3 PUFA acylation.
The effect of a non‐absorbable fat on the turnover of plasma cholesterol in the rat
Authors: Mattson Fred H. , Jandacek Ronald J.
Published: November 2006

Rats were injected with [4‐14C]‐cholesterol and then fed diets that contained sucrose polyester (SPE) at levels of 0 and 8% of the diet.14C was measured in neutral and acidic steroid fractions of the feces collected during days 35–39 post i.v. injection. Periodic blood samples were used to measure the specific activity of the plasma cholesterol. The plasma data were consistent with a two‐pool model for the decay of the plasma specific activity. The slow component of the decay curve decreased more rapidly in animals that received SPE. The half‐life corresponding to this component was approximately 20% shorter in the SPE‐fed animals compared to the control group. The mass of cholesterol calculated for the first pool was similar for all groups of animals. The14C found in the feces was consistent with the more rapid removal of cholesterol from the body in the SPE‐fed animals. The mass of excreted steroid was equal to the calculated rate of cholesterol production in each group of animals.
Unsaturated fatty acids compositional changes and desaturation during the embryonic development of the chicken (Gallus domesticus)
Authors: Noble R. C. , Shand J. H.
Published: November 2006

An investigation has been made to correlate the activities of the Δ9‐ and Δ6‐long chain fatty acid desaturation systems with the increased levels of oleic and arachidonic acids in the liver relative to the yolk sac membrane of the chick embryo during the last week of development. The membrane exhibited high levels of both stearic and linoleic acid desaturation in the early stages of yolk lipid mobilization, the activities of both enzyme systems decreasing with the approach of hatching. Stearic acid desaturation in the liver also decreased with the approach of hatching, but linoleic acid desaturation increased. The observed levels of desaturation in the yolk sac membrane are capable of making a conbryonic liver, the requirement for which does not appear to be satisfied by the yolk lipids. With the approach of hatching and the functional regression of the yolk sac membrane, the role is taken over by the embryonic tissues.
Preparation of hydroperoxy and hydroxy derivatives of rat liver phosphatidylcholine and phosphatidylethanolamine
Authors: Terao J. , Asano I. , Matsushita S.
Published: November 2006

A convenient method for the preparation of hydroperoxy and hydroxy derivatives of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) is described. PC and PE obtained from rat liver were oxidized with singlet oxygen by using methylene blue as the photosensitizer, and their hydroperoxides were isolated with the aid of reverse phase liquid chromatography. The hydroxy derivatives were obtained by reducing the hydroperoxides with sodium borohydride. The results of gas chromatography mass spectrometry revealed that hydroxy fatty acid components of the hydroxy derivatives were derived from isomeric hydroperoxides of oleic acid, linoleic acid, arachidonic acid and docosahexanoic acid. Normal phase high performance liquid chromatography did not separate the hydroperoxy and hydroxy derivatives from the respective unoxidized phospholipids, although unoxidized PC and PE were separated from each other. However, the hydroperoxy and hydroxy derivatives could be distinguished from unoxidized phospholipid species on reversed phase thin layer chromatography.
Stimulation by lipoxygenase products of superoxide anion production in FMLP‐treated neutrophils
Authors: Beckman Jeffrey K. , Gay James C. , Brash Alan R. , Lukens John N. , Oates John A.
Published: November 2006

Our recent observation that leukotriene B4 (10−9M) is a potent enhancer of FMLP‐initiated neutrophil superoxide anion formation prompted an evaluation of the ability of other lipoxygenase products and related compounds to modulate this response. The results indicate that FMLP‐evoked O2− may be enhanced by 10−8–10−7 M levels of a number of lipids, in addition to LTB4, including 5‐HPETE, 5‐HETE, 5,15‐DiHPETE and by higher levels of other 15‐series lipoxygenase products and arachidonic acid. It is of interest that the relative potency of these agents in potentiating the superoxide response to FMLP approximately parallels their reported ability to induce chemotactic activity in leukocytes.
Oral polyunsaturated phosphatidylcholine reduces platelet lipid and cholesterol contents in healthy volunteers
Authors: Galli C. , Tremoli E. , Giani E. , Maderna P. , Gianfranceschi G. , Sirtori C. R.
Published: November 2006

The effects of orally administered polyunsaturated phosphatidylcholine (PPC) on plasma lipids, lipoproteins and platelet function and composition were studied in seven healthy male volunteers. PPC (Nattermann & Cie, GmbH, Cologne, Federal Republic of Germany), 10 g/day, was given for a 6‐week period after a 4‐week wash out; laboratory tests were repeated after a further 4‐week period after the end of treatment. PPC did not appear, during treatment, to modify the levels of plasma total cholesterol and triglycerides. High density lipoprotein (HDL) cholesterol levels were, however, increased after six weeks of PPC. The most dramatic changes occurred in platelet membrane composition: the total lipid/total protein and the cholesterol/protein ratios were reduced significantly, whereas increases of the phospholipid/total lipid ratio and of the linoleic acid membrane content were observed. Platelet function tests, both in whole blood and in platelet rich plasma, were not modified. Similarly, the thromboxane B2 formation after standard stimuli and the sensitivity to exogenous prostaglandin I2 also were unchanged. During the final wash out period following treatment, a reduction of plasma total and low density lipoprotein (LDL) cholesterol levels also was recorded. PPC appears to be capable of modulating lipid exchanges between cell membranes and the plasma compartment.
Foraging strategies involved in habitat use of shorebirds at the intertidal area of Chongming Dongtan, China
Authors: Jing Kai , Ma Zhijun , Li Bo , Li Jinhua , Chen Jiakuan
Published: November 2006

Dense flocks of migratory shorebirds from diverse species often concentrate in the intertidal areas for stopover. Trophic structure, food partition, prey availability and selectivity, predation risk, and abiotic factors are often used to explain the differences in habitat use of coexisting shorebirds. We sampled the macrobenthos and surveyed the distribution of shorebird populations to study the effects of foraging strategies on the habitat use of shorebirds at Chongming Dongtan, an important stopover site for shorebirds on the East Asian–Australasian Flyway. Results show that the relative abundance of epifaunal macrobenthos in salt marshes was much higher than that in the bare flats, whereas the relative abundance of infaunal macrobenthos in salt marshes was much lower than that in bare flats. The relative abundance of two life forms of macrobenthos was similar in the transitional zones between the salt marshes and the bare flats. Shorebirds with different foraging strategies exhibited different habitat uses. Pause‐travel shorebirds mainly utilized the salt‐marsh fringes, while tactile continuous shorebirds relied heavily on the bare flats. There was no significant difference in habitat use for visual continuous shorebirds. The density of tactile continuous shorebirds was positively correlated with bivalve density, and that of visual continuous shorebirds positively with crustacean density. Meanwhile, the relative abundance of pause‐travel foraging shorebirds was positively correlated with the relative abundance of epifaunal, but negatively with infaunal macrobenthos. In contrast, the relative abundance of tactile foraging shorebirds had a positive correlation with infaunal but a negative one with epifaunal life form. Therefore, foraging strategies may play important roles in shorebirds’ habitat use in intertidal areas.
Protein‐precipitating capacity of crude condensed tannins of canola and rapeseed hulls
Authors: Naczk M. , Amarowicz R. , Zadernowski R. , Shahidi F.
Published: November 2006

The protein‐precipitating potentials (PPP) of soluble condensed tannins (SCT) were determined in hulls from several samples of canola and rapeseed varieties. The PPP were expressed as slopes of lines (titration curves) reflecting the amount of SCT‐protein precipitated vs. the amount of SCT added to the reaction mixture. The slopes (Sp) of titration curves obtained using the protein‐precipitation assay ranged from 2.96 to 10.91 (absorbance units at 510 nm per mg SCT), and those of titration curves, obtained using the dye‐labeled bovine serum albumin (BSA) assay (Sd), ranged from 28.1 to 267 (% precipitated BSA per mg SCT). For both assays, a statistically significant (P≤0.001) semilogarithmic linear correlation existed between the slopes and the SCT contents in the canola and rapeseed hulls. Higher amounts of SCT‐protein complexes were precipitated at 40°C than at room temperature. Determination of titration curves under standardized conditions (type and concentration of protein, pH and temperature) afforded meaningful differences in the slopes among the range of SCT extracts from canola and rapeseed hulls used in this study.
Adaptation of the AOCS official method for measuring hydroperoxides from small‐scale oil samples
Authors: Crowe Tammy D. , White Pamela J.
Published: November 2006

An adaptation of the American Oil Chemists' Society Official Method Cd 8–53 for determining peroxides in fats and oils using a 0.5‐g sample is described. Comparisons of the Official Method and the small‐scale method were performed by analyzing soybean oil samples spiked with t‐butyl hydroperoxide and autoxidized soybean oil samples. A linear relationship between the Official Method and the small‐scale method was obtained with an R2 of 0.998. The small‐scale method is sensitive, precise, and suitable for small sample sizes and uses only about 10% of the chemicals necessary for the Official Method.
Effect of triacylglycerol structure on absorption and metabolism of isotope‐labeled palmitic and linoleic acids by humans
Authors: Emken E. A. , Adlof R. O. , Duval S. M. , Shane J. M. , Walker P. M. , Becker C.
Published: November 2006

The effect of dietary TAG structure and fatty acid acyl TAG position on palmitic and linoleic acid metabolism was investigated in four middle‐aged male subjects. The study design consisted of feeding diets containing 61 g/d of native lard (NL) or randomized lard (RL) for 28 d. Subjects then received an oral dose of either 1,3‐tetradeuteriopalmitoyl‐2‐dideuteriolinoleoyl‐rac‐glycerol or a mixture of 1,3‐dideuteriolinoleoyl‐2‐tetradeuteriopalmitoyl‐rac‐glycerol and 1,3‐hexadeuteriopalmitoyl‐2‐tetradeuteriolinoleoyl‐rac‐glycerol. Methyl esters of plasma lipids isolated from blood samples drawn over a 2‐d period were analyzed by GC‐MS. Results showed that absorption of the 2H‐fatty acids (2H‐FA) was not influenced by TAG position. The 2H‐FA at the 2‐acyl TAG position were 85±4.6% retained after absorption. Substantial migration of 2H‐16∶0 (31.2±8.6%) from the sn‐2 TAG position to the sn‐1,3 position and 2H‐18∶2n−6 (52.8±6.4%) from the sn‐1,3 position to the sn‐2 position of chylomicron TAG occurred after initial absorption and indicates the presence of a previously unrecognized isomerization mechanism. Incorporation and turnover of the 2H‐FA in chylomicron TAG, plasma TAG, and plasma cholesterol esters were not influenced by TAG acyl position. Accretion of 2H‐16∶0 from the sn‐2 TAG position in 1‐acylphosphatidylcholine was 1.7 times higher than 2H‐16∶0 from the sn‐1,3 TAG positions. Acyl TAG position did not influence 2H‐18∶2n−6 incorporation in PC. The concentration of 2H‐18∶2n−6‐derived 2H‐20∶4n−6 in plasma PC from subjects fed, the RL diet was 1.5 times higher than for subjects fed the NL diet, and this result suggests that diets containing 16∶0 located at the sn‐2 TAG position may inhibit 20∶4n−6 synthesis. The overall conclusion is that selective rearrangement of chylomicron TAG structures diminishes but does not totally eliminate the metabolic and physiological effects of dietary TAG structure.
Variations of trans octadecenoic acid in milk fat induced by feeding different starch‐based diets to cows
Authors: Jurjanz S. , Monteils V. , Juaneda P. , Laurent F.
Published: November 2006

The impact of starch sources differing in their velocities of ruminal degradation on the milk fat of dairy cows was studied. The animals received diets containing a slowly degradable (potatoes) or rapidly degradable (wheat) starch concentrate (40% of the dry matter) in a total mixed diet. Milk fat was the only animal performance factor affected: Cows produced significantly less milk fat when fed the wheat diet than the potato diet (−3.3 g/kg, −122 g/d; P<0.05). With the wheat diet, milk fat was poorer in short‐chain FA and richer in unsaturated longchain FA, especially in trans octadecenoic acid (4.4 vs. 2.7% of the total FA, P<0.05). A very large increase in the isomer trans‐10 18∶1 (+1.46% of the total FA) was observed. Because no difference in volatile FA concentrations in the rumen was revealed, the increase in trans octadecenoic acids, and particularly the isomer trans‐10 18∶1, was associated with the larger postprandial drop in ruminal pH with wheat. Similar concentrate levels and FA profiles in both diets indicated that the decrease in milk fat was due to changes in the ruminal environment. Quicker degradation of wheat starch, and hence a greater drop in pH with this diet associated with the absence of any effect on volatile FA, strengthen the hypothesis developed in the literature of enzyme inhibition via increased levels of trans octadecenoic acids, especially the trans‐10 isomer. Hence, milk fat can be decreased with rapidly degradable starch sources and not only with high levels of concentrates in the diet or added fat. More detailed work is necessary to elucidate the microorganisms involved and to determine whether metabolic pathways similar to those reported for high‐concentrate diets are involved.
Dietary protein modulates the effect of CLA on lipid metabolism in rats
Authors: Akahoshi Asuka , Koba Kazunori , Ichinose Fumika , Kaneko Mai , Shimoda Asako , Nonaka Kikuko , Yamasaki Masao , Iwata Toshio , Yamauchi Yoshie , Tsutsumi Kentaro , Sugano Michihiro
Published: November 2006

The effect of the interaction of CLA and type of dietary protein on lipid metabolism was studied in male rats by feeding diets containing casein (CAS) or soy protein (SOY) as dietary protein and either linoleic acid (LA, a control FA) or graded levels of CLA at 0,0.1, 0.5, and 1.0% for 28 d. CLA reduced the weight of perirenal adipose tissue in a dose‐dependent manner, but the magnitude of the reduction was greater when rats were fed SOY. Feeding SOY resulted in a significant reduction of the concentrations of serum total and HDL cholesterol, TG, glucose, and insulin irrespective of dietary CLA. The concentration of serum leptin tended to be lower on the SOY diet free of CLA than in the corresponding CAS diet, but it fell with an increasing dietary level of CLA in the CAS groups. In contrast, serum leptin tended to increase when CLA was added to SOY diets. The concentration of serum adiponectin was higher in the CAS than in the SOY groups, and it tended to increase in response to dietary CLA levels in the CAS‐fed rats, whereas CLA showed no effect in SOY‐fed rats. The activity of liver mitochondrial carnitine palmitoyltransferase was higher in the SOY than in the CAS groups, but it tended to increase with an increasing dietary level of CLA in both protein groups. Although the body fat‐reducing activity of CLA was more effective when the protein source was SOY, rats fed CAS appeared to be more susceptible to CLA than in those fed SOY with respect to cytokines examined. These results suggest that the type of dietary protein may modify the antiobesity activity of CLA.