bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of age and dietary fat (fish, corn and coconut oils) on tocopherol status of C57BL/6Nia mice
Authors: Meydani Simin Nikbin , Shapiro Alice C. , Meydani Mohsen , Macauley John B. , Blumberg Jeffrey B. 
Published: November 2006

AbstractThe effect of age and dietary fat type on tocopherol status was investigated using young and old C57BL/6Nia mice fed semipurified diets containing 5% (by weight) fish, corn or coconut oils and supplemented with 30, 100 or 500 ppm dl‐α‐tocopheryl acetate for 6 wk. Tocopherol levels in the diets, plasma, liver, kidney and lung were measured by high performance liquid chromatography following appropriate extractions. The results indicate that mice fed fish oil maintain lower plasma and tissue tocopherol concentrations than those fed corn and cononut oils (fish<corn oil<coconut oil). The difference was not due to a loss of tocopherol prior to consumption, but rather appeared to occur during the absorption process. Old mice had lower plasma and liver tocopherol concentrations than young mice. Old mice fed fish oil, however, maintained plasma tocopherol levels better than young mice fed fish oil, presumably due to their larger tocopherol pool. No age effect was detected on kidney and lung tocopherol levels. It is concluded that tocopherol status is affected by age and dietary fat type, especially fish oil.
Quantitation of baboon lipoproteins by high performance gel exclusion chromatography
Authors: Williams Mary C. , Kushwaha Rampratap S. , McGill Henry C. 
Published: November 2006

AbstractHigh performance liquid chromatography with gel exclusion columns was used for quantitative measurement of plasma lipoproteins. A combination of columns TKS 4000 PW and 3000 PW gave good separation of very low (VLDL), low (LDL) and high (HDL) density lipoproteins. The area under each lipoprotein peak detected by absorbance at 280 nm was measured by digitizing and was expressed as cm2. Purified lipoprotein standards isolated by ultracentrifugation were also chromatographed in increasing concentrations. The area under the lipoprotein standard peak was linearly related to the amount of total protein over a wide range. The areas of most of the measured plasma lipoproteins were within the linear range. The relationship between the area and the amount of protein for each standard was used to quantitate the amount of protein and was expressed as mg/dl plasma. This technique is simple and requires a small amount of plasma. The validated technique was applied to a large population of pedigreed baboons. An average plasma lipoprotein profile of feral baboons on the chow diet was characterized by a high level of HDL (90.9±30.7 mg/dl) with a lesser amount of LDL (29.1±13.2 mg/dl). VLDL was present in much lower concentration (8.6±2.6 mg/dl). Feeding a high cholesterol and high saturated fat (HCHF) diet raised both LDL (1.5‐fold) and HDL levels (1.3‐fold) without changing VLDL levels. Progeny of sires with low response to dietary cholesterol increased their HDL protein when challenged with HCHF diet without any change in their LDL or VLDL. Progeny of high‐responding sires, however, had increases in both their HDL and LDL levels when challenged with HCHF diet. The survey of lipoprotein profiles of the pedigreed baboon colony disclosed a number of animals with interesting and unusual lipoprotein patterns.
Identification of steroids by chemical ionization mass spectrometry
Authors: Lin Yong Y. 
Published: November 2006

AbstractChemical ionization (CI) mass spectra of various natural and synthetic steroids have been studied using methane, isobutane, ammonia, trideuterioammonia and hydroxy anion as reagent gases. The CI spectra of steroids give simple and well characterized ions, which provide information about molecular weight as well as functionalities in the molecules. Trideuterioammonia exchanges rapidly with active hydrogens (e.g., OH, SH, COOH, NH2) in steroid molecules in the CI reaction and thus provides a convenient means of active hydrogen determination by mass spectrometry. Application of various CI processes to the analysis of steroids and conjugates have been made. Low levels of hydroxycholesterols in biological samples and in cholesterol autoxidation products were identified by the 4 ion patterns, [M+NH4]+, [M−OH+NH3]+, [M−OH]+ and [M−H2 O−OH]+, in ammonia CI. The position of hydroxy functions in the cholesterol side chain can be identified from the methane CI of hydroxycholesterol trimethylsilyl (TMS) derivatives. Sterol carboxylic esters can be identified as the ammonium adduct ion of the intact molecule, [M+NH4]+, in ammonia CI. Isobutane and hydroxy anion CI spectra of the steroid esters give abundant ion fragments of both steroids and carboxylic acid moieties. Identification of free bile acids and steroid glycosides without derivatization is also feasible with the CI process when ammonia is used as reagent gas.
Analysis and structure determination of unsaturated 5β‐cholanoic acids
Authors: Kuksis A. , Child P. 
Published: November 2006

AbstractUnsaturated cholanoic acids are known to arise as artifacts of chemical transformation processes and during storage and high‐temperature gas liquid chromatography (GLC) of various derivatives of saturated bile acids. Nevertheless, there is evidence for their natural occurrence and isolation under conditions where artifactual formation of unsaturated bile acids would be unlikely. Since structural identification of such compounds is often complicated by a lack of knowledge of their analytical properties, a representative series of monounsaturated cholanoic acids with double bonds in rings A, B and C were prepared by POCl3 and ZnCl2 dehydration of saturated bile acids with selectively blocked hydroxyl functions. The cholenoic acids were indistinguishable from their saturated analogs by thin layer chromatography (TLC) on plain silica gel, but those compounds with sterically exposed double bonds were resolved by AgNO3‐TLC, using chloroform/methanol solvent systems. The synthetic 5β‐cholenoic acids obeyed the general rules of GLC mobility based on the overall shape of the molecule and the number and configuration of the functional groups. Constant retention factors attributable to the double bond were observed for all of the double bond types on several GLC phases, and theoretical retention times could be calculated for combinations of double bonds and functional groups not specifically represented among the synthetic standards. With gas chromatography‐mass spectrometry (GC‐MS), the unsaturated bile acids gave several characteristic fragments, which, in conjunction with the chromatographic properties of the parent compounds, permitted an unambiguous distinction among different unsaturated acids, and between unsaturated and saturated bile acids of the same number and configuration of functional groups. For complete structural identification of saturated and unsaturated bile acids, capillary GC‐MS represents the ideal state of the art, but the less expensive combination of AgNO3‐TLC and GLC also can yield much useful information concerning the structure of natural and synthetic 5β‐cholenoic acids. This study emphasizes the need for special precautions in the isolation and derivatization of bile acids intended for studies of unsaturated components.
Reduction of essential fatty acid deficiency in rats fed a low iron fat free diet
Authors: Ananda Rao G. , Manix Marcia , Larkin Edward C. 
Published: November 2006

AbstractYoung male rats were fed ad libitum for 8 weeks a low iron fat‐free (FF‐Fe) diet or a fat‐free diet supplemented with iron (FF+Fe). The relative levels of 16∶1 to 16∶0 and 18∶1 to 18∶0 in the total fatty acids of liver and other tissues (plasma, erythrocytes and intestinal mucosa) were considerably decreased because of a lack of dietary iron. In rats fed the FF‐Fe diet, the levels of essential fatty acids (18∶2ω6+20∶4ω6) in tissues were 2‐to 3‐fold greater than in the corresponding tissues of rats fed the FF+Fe diet. Eicosatrienoic acid (20∶3ω9) levels in tissue lipids from rats fed the FF+Fe diet were high (8–16%), whereas they were low (2–5%) in the case of animals fed the FF‐Fe diet. The proportion of 20∶4 in total fatty acids of tissues was 2‐to 3‐fold greater in rats fed the FF‐Fe diet than when they were fed the FF+Fe diet. Therefore, the relative levels of 20∶3ω9/20∶4ω6 varied from 1‐2.9 in tissue lipids of rats fed the FF+Fe diet, while it varied only from 0.2–0.3 in animals fed the FF‐Fe diet. These results suggest that a lack of dietary iron may reduce the synthesis of 16∶1, 18∶1, 20∶3 and 20∶4 and the metabolism of 20∶4.
Identification of chondrillasterol in twoCucurbitaceae seed oils by proton nuclear magnetic resonance spectroscopy
Authors: Iida T. , Jeong T. M. , Tamura T. , Matsumoto T. 
Published: November 2006

AbstractThe absolute configuration at C‐24 of C‐24 epimeric 24‐ethyl‐5α‐cholesta‐7,E‐22‐dien‐3β‐ols I–IV previously isolated from tea seed oil, shea fat, and gourd and sponge cucumber seed oils, respectively, was studied by proton nuclear magnetic resonance spectroscopy. The results showed that the sterols I and II are identical with spinasterol (24S/α‐ethyl group), whereas the sterols III and IV are identified as its 24R/β‐epimer, chondrillasterol. This study has thus for the first time properly documented the presence in tracheophytes of a 24β‐ethylsterol in which Δ25(27)‐bond is reduced.
Subfractionation and characterization of native and incubation enlarged human plasma high density lipoprotein particles by high performance gel filtration
Authors: Holmquist Leif , Carlson Lars A. 
Published: November 2006

AbstractIncubation of human plasma in vitro at 37 C results in an increase of the mean particle size of the high density lipoproteins (HDL) accompanied by an almost complete disappearance of the original particles present prior to incubation.A rapid high performance gel filtration technique has been developed in order to study the chemical composition of subfractions of native and incubation enlarged HDL particles as a function of particle size. Subfractionation of HDL isolated by preparative ultracentrifugation from 3 normal human plasmas incubaed in vitro at 0 and 37 C for 24 hr have been performed using a 150 cm long TSK‐G 3000 SW column. The separation time was less than 65 min.The curves obtained at high performance gel filtration of HDL, by monitoring the effluents from the column at 280 nm, agreed well both in positions of peak maxima and relative peak intensities with the particle distribution patterns observed at polyacrylamide gradient gel electrophoresis of the corresponding HDL preparations run in parallel. The different HDL particle subfractions of the effluents from the gel filtration column have been characterized by quantification of free and esterified cholesterol, total phospholipids and apolipoprotein A‐I and A‐II.The incubation enlarged HDL particles, subfractionated by the high performance gel filtration technique, were found to have a composition which differed from that of native HDL particles of corresponding size. Incubation enlarged HDL had a generally higher and almost constant relative cholesteryl ester content over the whole particle range compared to native HDL in which a continuous increase in relative cholesteryl ester content could be observed when going from large to small particles.The molar ratio of phospholipids to free cholesterol was higher in small native HDL particles than in the corresponding large ones. The relation between apolipoprotein A‐I and A‐II remained nearly constant between small and large HDL particles in each subfractionation experiment. The results demonstrate that the high performance gel filtration technique is a rapid and reproducible means for studying the composition of subfractions of HDL particle populations.
The monoenoic fatty acid composition of a marine species ofDesulfobulbus grown on lactate
Authors: Taylor James , Parkes R. John , Wahle Klaus W. J. , Calder A. Graham 
Published: November 2006

AbstractThe proportions of isomeric monoenoic fatty acids from cell lipids of a marine, anaerobic, sulphatereducing bacteriumDesulfobulbus, grown on lactate, were determined by pyrrolidide derivatization and GC‐MS analysis. The predominant fatty acid was C17ŋ1, Δ11 with much smaller proportions of C16∶1, Δ11 and C18∶1, Δ11 and small (<5%) yet significant proportions of C15∶1, Δ11; C16∶1, Δ9; C17∶1, Δ9 and C18∶1, Δ9. If the spectrum of isomers obtained from this organism were synthesized entirely by the anaerobic pathway, it would indicate a wider chain‐length specificity for the ratelimiting β‐hydroxy acyl dehydrase than hitherto has been reported. The high proportion of oddnumbered fatty acids reflected the chain initiation by propionate derived from lactate. The possibility of monoene synthesis by an anaerobic Δ9‐desaturase mechanism is discussed.
Mass spectrometry of isomeric fatty acid hydroperoxides by chemical ionization via direct exposure probe
Authors: Plattner R. D. , Gardner H. W. 
Published: November 2006

AbstractIntact isomeric methyl 9‐ and 13‐hydroperoxy linoleates are analyzed by chemical ionization (CI) mass spectrometry using a direct exposure probe. Both isobutane and ammonia CI spectra were obtained. With isobutane CI, ions are observed for protonated fragments that are indicative of an acid catalysis mechanism similar to that observed in solution, whereas ammonia CI yields primarily adduct ions. The collisionally activated decomposition daughters of the high mass ions can be used to identify the position of the hydroperoxy group in the isomers studied.
Fatty acid metabolism and cell proliferation. VII. Antioxidant effects of tocopherols and their quinones
Authors: Lindsey Jenifer A. , Zhang Hanfang , Kaseki Hisayuki , Morisaki Nobuhiro , Sato Takasi , Cornwell David G. 
Published: November 2006

AbstractThe antioxidant capacities of α‐ and γ‐tocopherols (α‐E and γ‐E) and their quinones (α‐EQ and γ‐EQ) were determined in non‐biological and biological systems. The non‐biological system consisted of arachidonic acid [20∶4 (n−6)], the oxidant cumene hydroperoxide, and a Fe3+ catalyst to facilitate malondialdehyde (MDA) formation from lipid peroxides. α‐E and γ‐E had similar antioxidant capacities in this system. α‐EQ also functioned as an antioxidant, while γ‐EQ exhibited a crossover effect by functioning as an antioxidant at low concentrations and a prooxidant at high concentrations. Biological lipid peroxidation in smooth muscle cells challenged with 20∶4 (n−6) was measured both by MDA formation in confluent cultures and by cell growth in proliferating cultures. α‐E, γ‐E and α‐EQ had similar antioxidant capacities, but γ‐EQ was highly cytotoxic for cells in both confluent and proliferating cultures. Cellular retention of antioxidants was estimated indirectly from MDA formation when cells were loaded with an antioxidant (preincubation) and then incubated for varying periods of time in fresh media containing 20∶4 (n−6). Cellular retention also was measured directly with tritiated α‐E and tritiated αEQ. These studies showed that cellular retention decreased in the sequence γ‐E>α‐E>α‐EQ. Thus, cellular retention does not explain the enhanced antioxidant capacity of α‐E compared to γ‐E that has been reported for animal systems. The antioxidant capacity of αE evidently is enhanced by its metabolism to a quinone which, unlike the quinone from γ‐E, functions as a biological antioxidant.
Influence of dietary partially hydrogenated vegetable and marine oils on membrane composition and function of liver microsomes and platelets in the rat
Authors: Blomstrand Rolf , Diczfalusy Ulf , Sisfontes Leslie , Svensson Lennart 
Published: November 2006

AbstractThe aim of the present study was to investigate the influence of partially hydrogenated vegetable and marine oils on membrane composition and function of liver microsomes and platelets with particular reference to the metabolism of linoleic acid and the production of arachidonic acid metabolites. Four groups of male weanling rats were fed linoleic acid supplemented diets containing 20% (w/w) of partially hydrogenated low erucic acid rapeseed oil (HLRSO), partially hydrogenated herring oil (HHO), olive oil (OO) and trierucin + triolein (TE) for 10 weeks. An additional two groups were fed partially hydrogenated low erucic acid rapeseed oil and partially hydrogenated herring oil without linoleic acid supplementation (HLRSO‐ and HHO‐, respectively).Substantial amounts oftrans fatty acids were incorporated into liver microsomes (12.6% in group HLRSO) and platelets (7.0% in group HLRSO‐). This incorporation was not dependent on the dietary linoleic acid level. Hepatic microsomal Δ5‐desaturase activity was significantly increased after HLRSO feeding compared to OO feeding. Δ6‐Desaturase activity did not vary in the linoleic acid supplemented groups. Both Δ5‐ and Δ6‐desaturase activities were significantly increased in groups without linoleic acid supplementation.Docosenoic acid was incorporated into platelet phospholipids in contrast to liver microsomes. In the platelet, docosenoic acid seemed to have a special preference for phosphatidylserine. Very small amounts were incorporated into platelet phosphatidylinositol. Feeding diets HLRSO, HHO and OO did not influence rat platelet cyclooxygenase or 12‐lipoxygenase activity. Platelets from rats fed TE, however, produced significantly less 12‐hydroxy‐5,8,10,14‐eicosatetraenoic acid (12‐HETE) than platelets from rats fed OO. Feeding of HLRSO‐ and HHO‐ resulted in a significantly diminished production of the arachidonic acid metabolites 12‐HETE, 12‐hydroxy‐5,8,10‐heptadecatrienoic acid (HHT) and 6‐keto‐prostaglandin F1α in stimulated platelets and aorta. Thus, high dietary levels oftrans isomers of monoenoic acids do not interfere with platelet cyclooxygenase or lipoxygenase activity provided sufficient amounts of linoleic acid are available.
Dimers formed in oxygenated methyl linoleate hydroperoxides
Authors: Miyashita Kazuo , Hara Nobuko , Fujimoto Kenshiro , Kaneda Takashi 
Published: November 2006

AbstractThe formation of dimers was demonstrated in methyl linoleate hydroperoxides decomposed by bubbling with dry air at 30 C. The dimer fraction isolated by gel permeation chromatography was further fractionated by successive silicic acid column and high performance liquid chromatography. Major components were analyzed after derivatizations by gas chromatography‐mass spectrometry with several ionization methods, i.e., electron impact, chemical ionization and field desorption.After aeration for 90 min, 1.4% of the hydroperoxides were decomposed. However, almost all of the secondary products were dimers, while polar monomeric and low molecular products were negligible. After aeration for 390 min, both polar monomeric (5.0%) and low molecular (0.8%) compounds formed, but dimers and polymers (18.1%) were still the major products. These results show the importance of polymerization in the aerobic breakdown of hydroperoxides.The dimers isolated from hydroperoxides aerated 90 min could be separated into two fractions according to their polarities. The dimers identified usually were composed of octadecadienoate and oxygenated octadecenoate moieties crosslinked through either ether or peroxy linkages across C‐9 or C‐13 positions. The oxygen‐containing functional groups found in the dimers include hydroperoxy, hydroxy and oxo groups. The polar dimers had two of these groups per molecule, while the less polar dimers had one. The main constituents of dimers were linked through peroxy bridges and found to be similar to the dimers previously identified in autoxidized methyl linoleate. These dimers are suggested as important intermediates in linoleate oxidation and as precursors of flavor deterioration.
Chemical defence, offence and alliance in ants–aphids–ladybirds relationships
Authors: Pasteels Jacques M. 
Published: November 2006

AbstractChemicals, which mediate the interactions between aphids, ladybirds and ants, are reviewed. Special emphasis is laid on autogenous and plant‐derived chemical defence in aphids and ladybirds. Evidences for chemical cues used during foraging and oviposition in ladybirds are assessed. Possible mutualistic interaction between plants and the third trophic level is illustrated by the as yet few reports of indirect plant‐defence volatiles induced by aphids or coccids attracting parasitoids or ladybirds. The use of chemical signals allowing aphid parasitoids or ladybirds to squeeze into ant–aphid mutualistic association is briefly described. Questions are raised and hypotheses suggested which could stimulate further research on aphid host‐plant influence on ladybird foraging behaviour and fitness, and on the cues used by aphid‐web partners for their mutual recognition.
Breeding migration and population stability
Authors: Nakazawa T. , Yamamura N. 
Published: November 2006

AbstractWe have modeled habitat shift for reproduction to examine the relationship between the timing of migration and population stability, by modifying Takimoto's (Am Nat 162:93–109, 2003) consumer–resource model with a consumer's ontogenetic niche shift. We found that equilibrium was always locally unstable if migration occurs at a fixed time or level of energy storage, whereas it could be stable if the timing of migration was adaptively flexible to maximize reproductive output. The general conditions for stability were safer breeding rather than feeding habitat and abundant resources at the feeding habitat. These results imply that both adopting an adaptive plastic strategy in the timing of migration and choosing to migrate from a rich feeding habitat to a safe breeding habitat can contribute to population stability. We also found that reduced reproductive success with delays in migration, and the survival rate after reproduction, had complicated effects on stability, depending on resource availability at the feeding habitat. The equilibrium was more likely to be stable when reproduction success was only slightly (or greatly) reduced or survival rate was high (or low) if the feeding habitat was rich (or poor). These are significant predictions for ecological study of migrating animals.
Oxidative stability of virgin olive oils
Authors: Cinquanta L. , Esti M. , Di Matteo M. 
Published: November 2006

AbstractAn investigation was carried out on virgin olive oils of the Gentile (Larino), Gentile (Colletorto), Coratina, and Leccino varieties, harvested at different times, to assess their oxidation stability. The olive oils were analyzed by means of peroxide, K232′ and K270 values at 1, 6, 12, and 18 mon of storage in green bottles, in the dark, at temperatures ranging from a mean of 6°C in winter to 12°C in summer. A subsample was also oven‐tested at 75°C and then analyzed on a weekly basis using the same oxidative parameters. The less ripe the olives (harvested in the same area during 1 mon), the more resistant the olive oils were to forced oxidation. The amount of total phenols in the oils was found to be directly related, even if to a low degree, to the oleuropein content in the olives and inversely related, to the same degree, to (3,4‐dihydroxyphenyl)ethanol. The latter is a derivative of oleuropein; (3,4‐dihydroxyphenyl)ethanol content increases as the olives ripen, but it is very low in fresh virgin olive oils, owing to the hydrophilic nature of the phenolic alcohol, which goes mainly into the waste‐water during processing. Among the varieties considered, Coratina oils showed the highest resistance to forced oxidation because of their high total phenol content.