bluuebunny/crossref_metadata_2025 huggingface dataset:
Lipids and lipophilic pollutants in three species of migratory shorebirds and their food in shepody bay (Bay of Fundy, New Brunswick)
Authors: Napolitano Guillermo E. , Ackman Robert G. , Parrish Christopher C.
Published: November 2006

To study food web transfers of lipids in the intertidal zone, three specimens of each of the semipalmated sandpiper (Calidris pusilla [L.]), the semipalmated plover (Charadrius semipalmatus Bonaparte) and the short‐billed dowitcher (Limnodromus griseus [Gmelin]) were examined after capture during the summer of 1989. They were feeding intensively, prior to migration, on the amphipod,Corophium volutator, on the mudflats of Dorchester Cape, New Brunswick, Canada. The ragworm,Nereis diversicolor, and samples of sea foam were also collected from the mudflats at the same location in 1989 and 1990. Total body lipids of semipalmated sandpipers and short‐billed dowitchers were about 20% of the wet weights, while those of the semipalmated plovers ranged from 35 to 40%. Adipose tissue fatty acids showed a trend from marine fatty acids (20∶5n−3, 22∶6n−3) at 10% ofC. pusilla acids through 5% inC. semipalmatus to 1% inL. griseus. These proportions confirm differences in feeding habits proposed from analyses of gut contents. Short‐billed dowitcher adipose fat included the lowest values of polychlorinated biphenyls (0.078 to 0.266 ppm). The other two species of shore‐birds showed levels as high as 1.64 ppm. Concentrations of 1,1‐bis(4‐chlorophenyl)‐2,2,2‐trichloroethane and 2,2‐bis(4‐chlorophenyl)‐1,1‐dichloroethylene were also variable, but with three exceptions were ≤0.1 ppm of adipose fat. Sea foam collected in the tidal channels and at the edge of the water during the rising tides was found to include diverse lipophilic materials, capable of transfer to higher trophic levels. Triacylglycerols, phospholipids, sterols, hydrocarbons and pigments were typically present at a concentration of 65×103 μg/L. The long‐chain isoprenoid squalene, of endogenous origin and apparently derived from featherwax, was the only hydrocarbon present in the depot fats of the three species of birds analyzed. This indicates that the birds basically inhabited a pristine environment free of hydrocarbon pollutants. The hydrocarbon present in the sea foam consisted of a series of normal alkanes, from C20 to C39, with no odd/even chain‐length preference (carbon preference index=1.008). These hydrocarbons probably originated in detritus from decaying vascular plants but could possibly reflect a very low level of petroleum contamination. The lack of local pollution appears to favor continued success of the migratory pattern of these birds.
Dietary fat and breast cancer
Authors: Carroll Kenneth K.
Published: November 2006

High‐fat diets are throught to increase the risk of breast cancer because animals develop mammary cancer more readily when they are fed high‐fat compared to low‐fat diets, and breast cancer incidence and mortality are higher in countries with high‐fat as compared to those with lowfat diets. Prospective cohort studies and case‐control studies have failed to provide much support for this theory, but such studies are less capable of showing the relationship because of smaller differences in dietary fat intakes of the study populations; difficulties in assessing the diets of individuals over a period of time; and possible differences in genetic susceptibility of cases and controls to breast cancer. Studies on migrants have shown that breast cancer incidence and mortality increase in populations who move from countries with low‐fat to those with high‐fat diets, indicating that observed geographical differences in breast cancer are due to environmental rather than genetic factors. This is supported by time‐trend studies showing that breast cancer increases in countries as the level of fat in the diet rises. Controlled, long‐term dietary trials are needed to determine whether the converse is true: namely, that reduction of dietary fat can reduce the risk of breast cancer. Large groups are required to achieve statistical significance, but smaller numbers may be adequate for studies on high‐risk individuals. Preliminary experiments already have demonstrated the feasibility of carrying out such dietary trials.
Dietary fat, fatty acids and prostate cancer
Authors: Rose David P. , Connolly Jeanne M.
Published: November 2006

International comparisons suggest a relationship between prostate cancer incidence and dietary fat, an inference supported by migration studies, the changing incidence rates and levels of animal fat consumption in Japan and the results from some case‐control studies. Overall, however, epidemiological studies have been inconclusive, and although prostate cancer is one of the hormone‐dependent tumors, evidence of interactions between dietary fats and male endocrine function is incomplete. Laboratory experimentation has shown that n−6 fatty acids stimulate and n−3 fatty acids inhibit human prostate cancer cells in culture; also, feeding diets rich in marine oils suppresses growth of these cells as solid tumors in athymic nude mice. These growth effects of polyunsaturated fatty acids appear to involve both prostaglandins and leukotrienes and to interconnect with autocrine regulation by epidermal growth factor‐related polypeptides.
Dietary fat and the development of pancreatic cancer
Authors: Roebuck B. D.
Published: November 2006

Pancreatic cancer is the fifth most common cause of death due to cancer. Except for an association with cigarette smoking, its etiology is poorly understood. Because of the dearth of epidemiological clues as to causation, studies with experiemntal animal models assume greater importance. Rodent models of pancreatic cancer indicate that while dietary fatper se does not cause pancreatic cancer, it does enhance or promote tumor development. Subsequent to treatment with a pancreatic carcinogen, high intakes of dietary unsaturated fats of the n−6 series, but not saturated fats, enhance or promote tumor development. A requisite level of linoleic acid is needed for this promotion. Fats of the n−3 series (e.g., certain fish oils) are inhibitory to tumor growth. Promotion by dietary fats appears only partly related to the high caloric content of fat. Mechanistically, certain dietary unsaturated fats appear to selectively enhance the growth rate of carcinogeninduced, pre‐cancerous lesions. Irrespective of precise understanding of mechanisms of promotion, it, appears possible to intervene in the process of cancer development and reduce the burden of cancer. Experimentally, this may be accomplished by decreasing total fat intake, decreasing caloric intake, increasing exercise or increasing the intake of n−3 fatty acids.
Dietary fat and colon cancer: Animal model studies
Authors: Reddy Bandaru S.
Published: November 2006

Since it was first suggested that high dietary fat is a risk factor in colon cancer, there have been several studies to test this hypothesis. Epidemiologic studies suggested a positive association between dietary fat and colon cancer. Laboratory animal model studies demonstrated that not only the amount of rat, but also types of fat differing in fatty acid composition are important determining factors in colon tumor development. Chemically‐induced colon tumor incidence was increased in rats fed the semipurified diets containing 23% corn oil, safflower oil, lard or beef tallow (high‐fat) as compared to those fed 5% corn oil, safflower oil, lard or beef tallow diets (low‐fat). Diets containing 23% conconut oil, olive oil or fish oil, or high‐fat diets containing varying levels oftrans fat, had no colon tumor‐enhancing effect compared to their respective low fat diets. The stage at which the effect of dietary fat is exerted appears to be mostly during the post‐initiation phase of colon carcinogenesis. Lack of a colon tumor enhancing effect of dietary fish oil is observed both during the initiation and postinitiation phases. The mechanisms by which various dietary fats increase colon carcinogenesis are not fully understood. In most instances, however, the high‐fat diet appears to enhance tumorigenesis through elevation of agents, such as secondary bile acids, that act as promoters of tumor development. Lack of colon tumor promotion by dietary fish oil andtrans fat appears to be mediated through their effect on mucosal ornithine decarboxylase activity, colonic secondary bile acids and/or prostaglandin synthesis.
Utilization of extracellular lipids by HT29/219 cancer cells in culture
Authors: Pazouki S. , Baty J. D. , Wallace H. M. , Coleman C. S.
Published: November 2006

Uptake and incorporation of long‐chain fatty acids were studied in a human colorectal cancer cell line (HT29/219) grown in culture medium supplemented with either fetal calf serum (FSC) or horse serum (HS). The cells were grown for 120 h with no change of medium; the two major cellular lipid classes, the phospholipids and the triacylglycerols, were analyzed at regular time‐points. We observed significant changes in the concentration of most fatty acids throughout culture, and differences in their composition when different sera were used to supplement the medium. Minimal levels of free fatty acids were found in the cells, indicating a very small “free fatty acid pool”. A major difference between the cells grown in media supplemented with different sera was the changes observed in concentrations of cellular polyunsaturated fatty acids during growth. In cells grown with FCS (in which 20∶4n−6 is present), the levels of this acid in the phsopholipid and triacylglycerol fractions declined rapidly during cell growth, suggesting further metabolism. In cells grown in medium supplemented with HS, 18∶2n−6 was the major polyunsaturated acid present. There was clear evidence that this acid accumulated in the cellular triacylglycerol and phospholipid fractions. Furthermore, its concentration did not decline during growth in culture, suggesting minimal conversion to other polyunsaturated n−6 acids. Our results suggest that fatty acids from additional sources in the medium, for example triacylglycerols and phospholipids associated with the lipoproteins, are taken up by the cells. There is also indication of cellular fatty acid synthesis, particularly of monounsaturated and saturated acids during the culture period. HT29/219 cells were shown to take up and incorporate radioactivity when trace amounts of [1‐14C]‐labeled arachidonic, linoleic or oleic acids were added to the culture medium. Most (80%) of the label was detected in cellular phospholipids and triacylglycerols, although the specific activities of these various fatty acids were different in the two lipid fractions.
Effects of aging on the content, composition and synthesis of sphingomyelin in the central nervous system
Authors: Giusto Norma M. , Roque Marta E. , Ilincheta de Boschero Monica G.
Published: November 2006

Sphingomyelin (SPH) content and composition in different regions of the brain were analyzed in 2.5, 21.5 and 26.5‐month‐old rats. SPH content increased in the cerebral hemispheres, cerebellum and medulla oblongata plus pons as age increased. The highest SPH content was observed in 26.5‐month‐old rats, with values increasing by 1.74, 2.75 and 0.88‐fold, respectively, over 2.5‐month‐old rats. The SPH fatty acid composition of brains from aged rats was markedly different from that of adult rats. Between 2.5 and 26.5 months of age the monoenoic/saturated fatty acid ratio increased from 0.22, 0.30 and 0.54 to 0.54, 0.68 and 1.03 in cerebral hemispheres, cerebellum and medulla oblongata plus pons, respectively. The percentage and content of fatty acids longer than 22 carbon atoms esterified to SPH increased with age from 18, 26 and 44 to 48, 52 and 62 mole % in cerebral hemispheres, cerebellum and medulla oblongata plus pons in 26.5‐month‐old rats. In subcortical white matter from aged rats, monoenoic 22–26 carbon atom fatty acids increased more than the saturated ones in 21.5‐month‐old rats relative to 2.5‐month‐old rats.In vitro synthesis of SPH from [3H]choline and [3H]palmitic acid in cerebral cortex and cerebellum showed no significant differences between adult rats and those 21.5 months of age. In cerebellum and in cerebral cortex, [14C] serine incorporation increased in aged rats. The results suggest that aging induces increases in both SPH content and in the monoenoic/saturated fatty acid ratio. These increases are quantitatively different in all brain regions analyzed.
Determination of β‐carotene in plasma, blood cells and buccal mucosa by electrochemical detection
Authors: Murata Takuji , Tamai Hiroshi , Morinobu Takao , Manago Mitsuhiro , Takenaka Akira , Takenaka Hiroyuki , Mino Makoto
Published: November 2006

The β‐carotene concentrations in plasma, blood cells and buccal mucosal cells were determined by high‐performance liquid chromatography with electrochemical detection. This method was 1,000 times more sensitive than the conventional spectrophotometric method. Polymorphonuclear cells and red blood cells had lower β‐carotene levels than the other cells. After oral administration of 580 mg/day of all‐trans β‐carotene to human male volunteers for a week, the β‐carotene concentrations in all cell types increased at least several times above the original levels.
Gender and dietary fat affect α‐tocopherol status in F344/N rats
Authors: Chen Haw‐Wen , Cook Laura R. , Hendrich Suzanne
Published: November 2006

For four weeks, groups of eight male and eight female F344/N rats were fed diets containing 15.5, 20, 30 or 40% of energy (en%) as fat. The fat was composed of corn oil and beef tallow with 9 en% from linoleate in all diets. Females had greater mean hepatic α‐tocopherol levels, whereas males had greater plasma α‐tocopherol and cholesterol concentrations. In males, the plasma ratio of α‐tocopherol/cholesterol was significantly greater than in females (P<0.05). Plasma α‐tocopherol increased with increasing en% fat (r=0.51,P<0.001) in both sexes, but dietary fat did not alter hepatic α‐tocopherol levels. These results suggest that plasma α‐tocopherol may serve as a biomarker of total dietary fat intake and that in F344/N rats gender differences affect α‐tocopherol and cholesterol status.
The absorption of fish oils and concentrates
Authors: Ackman R. G.
Published: November 2006

Both preventive and curative therapies have created a considerable demand for eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids. The most common sources for ω3 fatty acids are fish oil. The concentrations of EPA and DHA in commercial oils, after modest enrichment, reach about 300 mg/g; alternative technologies can produce reasonably priced fish oils containing 400 or even 500 mg/g of ω3 acids. When the acids are liberated from the glycerides, concentrates of ethyl esters or free acids with 65 to 70% total ω3 fatty acids (at least 50% EPA+DHA) are readily prepared. Difficulties have arisen because most clinical trials have used fish oils of unspecified composition, and some trials are now based on either ethyl esters or free acids. There are at least three different, but not mutually exclusive, absorption routes in humans, namely the preduodenal route, the lymphatic routevia chylomicrons, and the routevia the portal vein to the liver. This makes it difficult to compare results. The difficulty in obtaining dose‐related clinical data may in part be due to the form in which the ω3 acids are offered and due in part to the natural presence of these fatty acids in the body. The nontriglyceride forms, especially the free acids, have been advocated for standardization of trials to facilitate interlaboratory comparisons.
Human mammary gland function at the onset of lactation: medium‐chain fatty acid synthesis
Authors: Spear M. L. , Bitman J. , Hamosh M. , Wood D. L. , Gavula D. , Hamosh P.
Published: November 2006

The onset of medium‐chain fatty acid synthesis in the human mammary gland was investigated. Colostrum and serum were collected from 31 healthy women and the fatty acid composition of total lipid was analyzed by gas‐liquid chromatography. Although colostrum/serum ratios for most fatty acids range from 0.7–2.4, very low levels of 10∶0 and 12∶0 were present in serum lipids as compared to much higher concentrations of these fatty acids in colostrum lipids (colostrum/serum ratio 16.23 and 17.11 for 10∶0 and 12∶0, respectively). We have previously found that medium‐chain fatty acid levels are very low inprepartum mammary secretions (6–10 wk before term delivery) but are higher and similar in colostrum of women who deliver preterm (3–14 wk) or at full term. The data indicate that parturition, irrespective of length of pregnancy, is the trigger for medium‐chain fatty acid synthesis in the human mammary gland.
Neutral glycolipids of human and bovine milk
Authors: Newburg David S. , Chaturvedi Prasoon
Published: November 2006

The neutral glycolipids of milk, a small fraction of the total lipids, are of potential biological importance. The simultaneous quantitation of the simple (less than five sugars) glycosphingolipids of human milk samples was achieved by high‐pressure liquid chromatography. The samples, representing various stages of lactation, parity of the nursing child, and age of the mother, contained similar glycolipid patterns, but with varying individual glycolipid concentrations. The cerebrosides are major glycosphingolipids of human milk: the non‐hydroxylated fatty acid (NFA)‐containing species are present at 1.8 μM, and the hydroxylated and/or short‐chain fatty acid‐containing species (HFA) are present at 1.7 μM; NFA lactosylceramide is present at 931 nM. The cerebrosides appear to be primarily galactosylceramides (galactocerebrosides); glucosylceramides (glucocerebrosides) are a minor component. Globotriaosylceramide (Gb3) is found at 50 nM and 73 nM for the NFA and HFA species, respectively, while globoside (Gb4) is found at 45 nM and 46 nM for the NFA and HFA species. Bovine milk glycosphingolipids differ from those of human milk, with bovine milk containing mainly NFA glucosylceramide (8 μM) and NFA lactosylceramide (17 μM); bovine milk contains little Gb3 or Gb4.
Influence of dietary fats on butyrylcholinesterase and esterase‐1 (ES‐1) activity in plasma of rats
Authors: Van Lith H. A. , Herman S. , Zhang X. , Van Der Palen J. G. P. , Van Zutphen L. F. M. , Beynen A. C.
Published: November 2006

We studied the effects of dietary fats, especially fish oil, on the activities of esterase‐1 (ES‐1) and butyrylcholine‐sterase in the plasma of rats. The identification of nutritional determinants of these enzymes could provide clues as to their physiological function. Fish oil, when compared with corn oil, consistently caused increased activities of both enzymes. Plasma ES‐1 activity, but not butyrylcholinesterase activity, was increased after isocaloric replacement of carbohydrates by coconut fat. Dietary medium‐chain triglycerides, when compared with corn oil, produced decreased and increased activities of butyrylcholinesterase and ES‐1, respectively. Various plant fats, such as corn oil, linseed oil, coconut fat, palm oil, palm kernel oil, soybean oil and rapeseed oil, did not differentially influence butyrylcholinesterase activities. Plasma triglyceride concentrations were lowered by fish oil and increased by coconut fat and palm kernel oil. For individual rats in 5 out of 6 experiments, weak, negative correlation coefficients of the order of 0.3 were found between the changes in plasma butyrylcholinesterase activities and in plasma triglyceride concentrations.
Modulation of fatty acid incorporation and desaturation by trifluoperazine in fungi
Authors: Kamisaka Yasushi , Yokochi Toshihiro , Nakahara Toro , Suzuki Osamu
Published: November 2006

The effects of trifluoperazine (TFP) on [1‐14C]fatty acid incorporation into the lipids ofMortierella ramanniana var.angulispora were studied. TFP decreased [1‐14C]‐fatty acid incorporation into phosphatidylcholine, phosphatidylethanolamine and triacylglycerol, but greatly increased14C‐labeling in phosphatidic acid. These changes in [1‐14C]fatty acid incorporation induced by TFP were accompanied by a decrease in desaturation of some [1‐14C]fatty acids taken up by the fungal cells. When [1‐14C]lioleic acid (LA) was incubated with the fungal cells, total γ‐linolenic acid (GLA) formation from incorporated [1‐14C]LA decreased, but the14C‐labeled GLA conent in individual lipid classes was essentially unchanged. This suggests that the site of the TFP effect on GLA formation from [1‐14C]LA taken up from the medium is not the desaturase acting on LA linked to complex lipids. On the other hand, GLA formation from [1‐14C]oleic acid was much less susceptile to TFP, which suggests that in this fungus Δ6 desaturation to GLA has at least two different pathways with different degrees of susceptibility to TFP.
Dependence of the bilayer phase transition temperatures on the structural parameters of phosphatidylcholines
Authors: Huang C. , Li Shusen , Wang Zhao‐qing , Lin Hai‐nan
Published: November 2006

Most saturated diacyl phosphatidylcholines C(X):C(Y)PC (saturated 1,2‐diacyl‐sn‐glycero‐3‐phosphocholine with X carbons in thesn‐1 acyl chain and Y carbons in thesn‐2 acyl chain), in excess water, can self‐assemble into lamellae which, upon heating, may undergo multiple thermotropic phase transitions at well‐defined, discrete temperatures. The transition temperature corresponding to the main or the gel to liquid‐crystalline phase transition (Tm) is known for many bilayers of fully hydrated phosphatidylcholines. In this study, we have analyzed the Tm values of 44 molecular species of phosphatidylcholines in terms of their structural and packing characteristics in the gel‐state bilayer. Two general equations are thus derived: Tm=162.26−3651.71 (1/N)−88.42 (ΔC/N) for C(X):C(Y)PC with X≥Y, and Tm=157.68−3525.44 (1/N)−93.28 (ΔC/N) for C(X):C(Y)PC with X<Y. Here, N is the minimal hydrophobic thickness of the dimeric C(X):C(Y)PC in the gel‐state bilayer and ΔC is the effective chain length difference between thesn‐1 andsn‐2 acyl chains for the monomeric C(X):C(Y)PC in the gel‐state bilayer. The advantage of these two equations in predicting the Tm values for phosphatidylcholines with ΔC/CL values in the range of 0.07 to 0.40 is their simplicity. A figure containing a total of 173 calculated Tm values is also presented.
Effect of cell density on cytotoxicity of ether lipid analogues in variants of B16 murine melanoma
Authors: Lligona Trulla Luis , Magistrelli Armondo , Salmona Mario , Teresa Tacconi Maria
Published: November 2006

Ether lipids are defined here as analogues of naturally occurring lysophosphatidylcholines with cytotoxic activity against neoplastic cells. The activity of 1‐O‐octadecyl‐2‐O‐methyl‐rac‐glycero‐3‐phosphocholine (ET18OMe) and 3‐hexadecylmercapto‐2‐methoxymethyl‐propyl‐1‐phosphocholine (Ilmofosine®) (BM 41.440) was tested in variants of B16 murine melanoma, grown in adhesion cultures (B16F1 with low metastatic potential; B16F10 and B16BL6 with high metastatic potential). Cytotoxicity was evaluated by counting the cells that survived after 24h of drug exposure. Cholesterol, sphingomyelin, total phospholipid and phosphatidylcholine levels were determined. After 24 h of drug exposure, cultures of the B16BL6 variant contained a larger number of cells, especially when high drug concentrations (100–250 μM) were used, than cultures of the B16F1 and B16F10 variants. The sensitivity of ET18OMe of the three variants was evaluated at different cell densities (at each density the dose was equalized per number of cells/well; 0.1 μmol/106 cells/well). In B16F1 and B16F10 cultures the dose‐response curve was not affected by the number of cells/well, while in B16BL6 no more than 20% of the cells were killed at all cell densities measured. A linear relationship was noted between cell density and cholesterol/phospholipid and sphingomyelin/phosphatidylcholine ratios in the resistant variant B16BL6, confirming that lipid composition modulates the cytotoxic activity of ether lipids.
Modulation of phorbol ester‐associated events in epidermal cells by linoleate and arachidonate
Authors: Belury Martha A. , Locniskar Mary , Fischer Susan M.
Published: November 2006

To elucidate the events elicited by the skin tumor promotor 12‐O‐tetradecanoylphorbol‐13‐acetate (TPA), which are modulated by linoleic acid (LA) and arachidonic acid (AA), the activity of these fatty acids in cultured mouse epidermal cells was compared. Approximately 94% of either exogenous radiolabelled fatty acid was incorporated into the total phospholipid pool over 15 h. The relative distribution among the phospholipid classes differed, however, such that approximately 70% of phospholipid‐associated [14C]‐LA was found in phosphatidylcholine, compared to approximately 30% for [14C]AA. Phosphatidylethanolamine and phosphatidylinositol/phosphatidylserine contained 17 and 13% of the phospholipid [14C]LA, and 34 and 30% of [14C]AA, respectively. Prostaglandin (PG) E2 production was low but similar in unstimulated cultures prelabelled with either [14C]LA or [14C]AA. However, in cultures treated with TPA (1.6 μM), [14C]AA‐prelabelling resulted in approximately three times the amount of [14C]PGE2 compared with cultures prelabelled with [14C]LA. Cultured cells were found to contain significant δ6 desaturase activity, which may enable conversion of LA to AA, and thus may account for the observed PGE2 production from [14C]LA treated cells. AA‐Supplemented (1.6 μM) cultures supported approximately twice the induction of ornithine decarboxylase activity by TPA compared with cultures treated with 1.8 μM LA. Activation of partially purified protein kinase C was similar for either fatty acid tested over a 10–300 μM dose range. Overall, the results suggest that LA does not have the same biological activity as AA with regard to several TPA‐associated events known to be important in skin tumor promotion. This reduced biological activity of LA may be partly responsible for the known inhibition of mouse skin tumor promotion by high dietary levels of LA [Leyton, J., Lee, M.L., Locniskar, M.F., Belury, M.A., Slaga, T.J., Bechtel, D., and Fischer, S.M. (1991)Cancer Res. 51, 907–915].
Compounds biologically similar to platelet activating factor are present in stored blood components
Authors: Silliman Christopher C. , Johnson Chris A. , Clay Keith L. , Thurman Gail W. , Ambruso Daniel R.
Published: November 2006

Agents which prime the neutrophil NADPH oxidase develop during routine storae of whole blood and packed red blood cells. This plasma priming activity can be inhibited by bepafant (WEB 2170), a specific platelet activating factor (PAF) receptor antagonist. Quantitation of the priming agent(s), by a commercially available radioimmunoassay for PAF, reproducibly demonstrated high levels of PAF activity. However, analysis of these plasma samples from stored blood components by gas chromatography/mass spectroscopy did not reveal any 1‐O‐alkyl‐2‐acetyl‐sn‐glycero‐3‐phosphocholine. We conclude that the polyclonal antibody to PAF used in these studies may have recognized different epitopes of a family of heterogeneous, biologically active lipids that manifest their effects through the PFA receptor.
Involvement of vitamin E and protein thiols in the inhibition of microsomal lipid peroxidation by glutathione
Authors: Palamanda Jairam R. , Kehrer James P.
Published: November 2006

Iron‐ascorbate stimulated lipid peroxidation in rat liver microsomes can be inhibited by glutathione (GSH). The role of protein thiols and vitamin E in this process was studied in liver microsomes isolated from rats fed diets either sufficient or deficient in vitamin E and incubated at 37°C unde 100% O2. Lipid peroxidation was induced by adding 400 μM adenosine 5′‐triphosphate, 2.5 to 20 μM FeCl3, and 450 μM ascorbic acid. One mL of the incubation mixture was removed at defined intervals for the measurement of thiobarbituric acid reactive substances (TBARS), protein thiols and vitamin E. In vitamin E sufficient microsomes, the addition of GSH enhanced the lag time prior to the onset of maximal TBARS accumulation and inhibited the loss of vitamin E. Treatment of these microsomes with the protein thiol oxidant diamide resulted in a 56% loss of protein thiols, but did not significantly change vitamin E levels. However, diamide treatment abolished the GSH‐mediated protection against TBARS formation and loss of vitamin E during ascorbate‐induced peroxidation. Liver microsomes isolated from rats fed a vitamin E deficient diet contained 40‐fold less vitamin E and generated levels of TBARS similar to vitamin E sufficient microsomes at a 4‐fold lower concentration of iron. GSH did not affect the lag time prior to the onset of maximal TBARS formation in vitamin E deficient microsomes although total TBARS accumulation was inhibited. Similar to what was previously found in vitamin E sufficient microsomes [Palamanda and Kehrer, (1992)Arch. Biochem. Biophys. 293, 103–109], GSH prevented the loss of protein thiols in vitamin E deficient microsomes. However, GSH did not protect efficiently against the loss of residual vitamin E in deficient microsomes. These data provide support for the concept that GSH protects against microsomal lipid peroxidation by maintaining protein thiols, and consequently vitamin E, in the reduced state. The lack of protection in vitamin E deficient microsomes may be related to the inability of such low levels of vitamin E to inhibit peroxidation.
Effect of varying proportions of dietary menhaden and corn oil on experimental rat mammary tumor promotion
Authors: Cohen Leonard A. , Chen‐Backlund Jye‐Yu , Sepkovic Daniel W. , Sugie Shigeyuki
Published: November 2006

Dose‐related effects of long‐chain highly unsaturated n−3 fatty acids on the development ofN‐nitrosomethylurea (NMU)‐induced rat mammary tumors were assessed in female F344 rats. Four test groups (36 rats/group) were fed the following high‐fat (HF) diets (23% fat, w/w): Group 1, 18% menhaden oil (MO) and 5% corn oil (CO); Group 2, 11% MO and 11.8% CO; Group 3,5% MO and 18% CO; Group 4, CO alone. A fifth group, serving as an internal control, was fed a low‐fat diet containing 5% CO alone. Experimental diets were begun after initiation with NMU, and the experiment was terminated 31 wk later. Total tumor numbers in the five groups were 28, 16, 32, 26 and 11, respectively, indicating that the promotion phase of NMU‐induced carcinogenesis was significantly suppressed only when equal parts of CO and MO (Group 2) were fed or when CO alone was fed at 5% (w/w). At high (Group 1) or low (Group 3) levels of MO, tumor numbers were indistinguishable from the HF CO group (Group 4). The same pattern was observed when assessed in terms of cumulative tumor incidence and multiplicity. However, when expressed in terms of final tumor incidence, dietary MO did not suppress tumor promotion in a statistically significant fashion at any concentration. Animals fed MO gained weight at the same rate as those fed CO, indicating that the presence of MO in the diet did not result in food avoidance behavior. Measurement of total serum cholesterol indicated an inverse trend with respect to the MO content of the diet. Analysis of serum fatty acid profiles indicated that the proportion of n−3 and n−6 polyun‐saturated fatty acids (PUFA) in the serum reflected that of the diet. These results support the hypothesis that the relative proportions of dietary n−3/n−6 fatty acids play an important role in the suppression of experimental mammary tumorigenesis and suggest that changes in circulating cholesterol or n−3 PUFA levels, induced by dietary MO, are not directly related to tumor development.
Pollen sterols from three species of sonoran cacti
Authors: Lusby W. R. , Buchmann S. L. , Feldlaufer M. F.
Published: November 2006

Cactus bees are important pollinators that contribute to the long‐term stability of arid regions in the United States. Since all insects are dependent upon a dietary source of sterol for normal growth, development and reproduction, a study was undertaken to determine neutral sterols available to cactus bees. The total neutral sterol composition of hand‐collected pollen was determined for three species of Sonoran cacti by gas‐liquid chromatography and mass spectrometry. 24‐Methylenecholesterol was the predominant pollen sterol in Engelmann's prickly pear,Opuntia phaeacantha, cholla,O. versicolor, and cardon,Pachycereus pringlei. Two pentacyclic triterpene alcohols, lupeol and moretenol, were also isolated. Since no cholesterol was detected in any of the pollen samples, cactus bees would have to utilize the 24‐alkyl sterols unchanged or convert these sterols to cholesterolvia dealkylation.
Garlic supplementation and lipoprotein oxidation susceptibility
Authors: Phelps Stacy , Harris William S.
Published: November 2006

Interventions which make serum lipoproteins less susceptible to oxidation may be antiatherogenic. The antioxidant properties of garlic which have been demonstratedin vitro led us to investigate the effects of garlic supplements on lipoprotein oxidation susceptibility in humans. Ten healthy volunteers were given 600 mg/d of garlic powder (6 tablets of Kwai®) for two weeks in a placebo‐controlled, randomized, double‐blind crossover trial. We found that although serum lipid and lipoprotein levels were not lowered in this short time period, theex vivo susceptibility of apolipoprotein B‐containing lipoproteins to oxidation was significantly decreased (−34%). Because garlic has been reported to beneficially affect serum lipid levels, platelet function, fibrinolysis and blood pressure, this additional effect of retarding lipoprotein oxidation may contribute to the potential antiatherosclerotic effect of garlic.
Transient activation of 1‐O‐alkyl‐sn‐glycero‐3‐phosphocholine: Acetyl‐CoA acetyltransferase during the incubation of macrophages
Authors: Sugiura Takayuki , Fukuda Teruo , Cheng Neng‐neng , Waku Keizo
Published: November 2006

The activity of the platelet‐activating factor (PAF)‐synthesizing enzyme, 1‐O‐alkyl‐sn‐glycero‐3‐phosphocholine (lysoPAF):acetyl‐CoA acetyltransferase (EC 2.3.1.67) in alveolar macrophage lysate was found to be elevated after warming the cells to 37°C. Such an increase in enzyme activity was detectable only when intact cells were warmed. The stimulation was transient, reaching a peak at 2 min, and then gradually decreased to the control level. We could not find increased PAF formation in warmed cells which had increased acetyltransferase activity, even though substantial amounts of lysoPAF were shown to be present within cells. In contrast, considerable amounts of PAF were formed after treatments of the cells with exogenous lysoPAF. These results suggest that the activation of acetyltransferase is not sufficient to induce PAF formation and that the increased availability of substrates, especially lysoPAF, in the cells is indispensable for triggering PAF biosynthesis in this type of cells.
Effects of an eicosapentaenoic and docosahexaenoic acid concentrate on a human lung carcinoma grown in nude mice
Authors: de Bravo M. G. , de Antueno R. J. , Toledo J. , De Tomás M. E. , Mercuri O. F. , Quintans C.
Published: November 2006

The effects of the n−3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), on the growth of a human lung mucoepidermoid carcinoma (HLMC) in athymic mice were studied. The mice were divided into three groups which were given either a control chow diet (C), a chow diet supplemented with EPA/DHA (P) (25 or 50 mg of free n−3 fatty acids/g of pellet/day), or chow diet supplemented with palmitic acid (S) (isocaloric with P). Two independent experimental schedules were followed: i) host mice bearing either tumors that were allowed to reach 4000 mm3, or only 35 mm3, were fed C, P or S for 21 or 41 days; ii) animals were fed C, P and S for 9 days before tumor implant and were maintained on these diets throughout tumor growth. Food consumption, mouse weight and liver/body weight ratio showed no significant differences between supplemented diets and chow. Tumor growth was markedly inhibited (45%) in both experiments by the EPA/DHA supplemented diet. In Experiment 2, only 60% of mice fed diet P had tumors. The fatty acid composition of neutral and polar lipids of host liver and tumor reflected the dietary intake of n−3 fatty acids; the content of arachidonic acid was reduced by 50%, and EPA/DHA was increased 3‐to 5‐fold. Tumor prostaglandin E2 levels were reduced 7.4‐fold in the P group. The reduced PGE2 content may be a factor in tumor growth inhibition.
Fatty acid composition of subcellular particles from sheep platelets and topological distribution of phosphatidylethanolamine fatty acids in the plasma membrane
Authors: Sánchez‐Yagüe J. , Cabezas J. A. , Llanillo M.
Published: November 2006

The fatty acid composition of individual phospholipids in subcellular fractions of sheep platelets and the asymmetrical distribution of phosphatidylethanolamine (PE) fatty acyl chains across the plasma membrane were examined. The main fatty acids of total lipid extracts were oleic (18∶1; 32–41%), linoleic (18∶2, 10–17%), stearic (18∶0; 13–15%), palmitic (16∶0; 11–15%) and arachidonic (20∶4; 8–12%) acids, with a saturated/unsaturated ratio of about 0.4. Each phospholipid class had a distinct fatty acid pattern. Sphingomyelin (SM) showed the highest degree of saturation (50%), with large proportions of behenic (22∶0), 18∶0 and 16∶0 acids. The main fatty acid in PE, phosphatidylserine (PS) and phosphatidylcholine (PC) was 18∶1n−9. Our findings suggest that fatty acids are asymmetrically distributed between thecholineversus the non‐choline phospholipids, and also between plasma membranes and intracellular membranes. The transbilayer distribution of PE fatty acids in plasma membranes from non‐stimulated sheep platelets was investigated using trinitrobenzenesulfonic acid (TNBS). A significant degree of asymmetry was found, which is a new observation in a non‐polar cell. The PE molecules from the inner monolayer contained higher amounts of 18∶2 and significantly less 18∶1 and 20∶5 than those found in the outer monolayer, although no major differences were detected in the transbilayer distribution of total unsaturatedversus saturated PE acyl chains.
Effect of ethanol on low density lipoprotein and platelet composition
Authors: Hojnacki Jerome L. , Cluette‐Brown Joanne E. , Deschenes Randall N. , Mulligan John J. , Osmolski Thaddeus V. , Rencricca Nicholas J. , Barboriak Joseph J. , Jakubowski Joseph A.
Published: November 2006

The present study was designed to investigate the effect of ethanol (EtOH) dose on low density lipoprotein (LDL) and platelet composition. Male squirrel monkeys were divided into three groups designated Control, Low, and High EtOH, and fed isocaloric liquid diets containing 0%, 12%, and 24% of calories as EtOH, respectively. After four months of treatment, monkeys fed the 12% alcohol dose had LDL and platelet cholesterol concentrations similar to Controls. By contrast, platelet membranes from High EtOH animals contained significantly more cholesterol which was associated with higher levels of plasma LDL cholesterol and apolipoprotein B. Blood platelet count, size, and mass were similar for all groups and circulating platelet aggregates were absent in the two alcohol cohorts. Despite elevations in platelet cholesterol mass and thromboxane A2 (TXA2) precursor, phospholipid arachidonate, platelet responsiveness, measured as thromboxane formed in response to a collagen challengein vitro, and the cholesterol/phospholipid molar ration, were not significantly altered by high dose alcohol. Normal platelet activity in High EtOH monkeys may have resulted from a significant increase in the platelet phospholipid polyunsaturated/saturated fatty acid ratio and a non‐significant increase in platelet phospholipid mass, both of which would have a fluidizing effect on platelet membranes. Our data indicate that low EtOH intake has no effect on platelet composition and function while unfavorable platelet cholesterol enrichment following consumption of high dose ethanol may arise from elevations in plasma LDL. Potentially thrombogenic (TXA2 formation, platelet aggregate formation) consequences of increased platelet cholesterol in squirrel monkeys fed high levels of alcohol may be averted by compensatory physicochemical changes in platelet membrane lipid composition although persistent elevations in circulating LDL may contribute to increased risk of cardiovascular disease.
Arachidonic acid, prostaglandin E2 and leukotriene C4 levels in gingiva and submandibular salivary glands of rats fed diets containing n−3 fatty acids
Authors: Alam S. Q. , Bergens B. M. , Alam B. S.
Published: November 2006

The effect of dietary n−3 fatty acids on prostaglandin E2 (PGE2) and leukotriene C4 (LTC4) levels in rat salivary glands and gingiva was examined in two separate nutritional studies. In the first set of experiments, two groups of male weanling Sprague‐Dawley rats were fed semipurified diets containing 10% corn oil (control group) or 10% menhaden oil (experimental group). Rats were killed after 8 wk on the diets; the fatty acid composition of total phospholipids and the concentrations of PGE2 and its precursor, arachidonic acid, were measured in gingiva and submandibular salivary glands (SMSG). Dietary n−3 fatty acids were incorporated into the tissue phospholipids. Arachidonic acid levels were reduced by 56% in gingiva and SMSG of rats fed menhaden oil compared with the control rats fed the diet containing corn oil. The concentrations of PGE2 in SMSG and gingiva of rats fed the diet containing menhaden oil were reduced by 74% and 83%, respectively. In a subsequent nutritional study, we tested whether the diet‐induced reduction in tissue arachidonic acid levels would also result in a corresponding decrease in LTC4 production. Three groups of rats were fed diets containing 5% corn oil (group 1), 4% ethyl ester concentrate of n−3 fatty acids plus 1% corn oil (group 2), or 5% ethyl ester concentrate of n−3 fatty acids (group 3). After 6 wk of feeding, gingiva and SMSG were analyzed for arachidonic acid content andin vitro production of LTC4. Arachidonic acid content of total phospholipids was about 60% lower in gingiva and 69% lower in SMSG of rats fed the ethyl ester concentrate of n−3 fatty acids (groups 2 and 3) than those of the control group fed the corn oil diet (group 1). Upon incubation with calcium ionophore, gingiva and SMSG from rats fed the n−3 fatty acids rich diet produced significantly less TLC4 than those from rats of the control group. Because PGE2 and LTC4 are believed to be important biochemical mediators of periodontal disease, one may speculate that a diet‐induced reduction in their levels may have a beneficial effect upon the course of the disease. The function of salivary glands may also be altered because of the role of these eicosanoids in salivary secretions.
Cholesterol metabolism in the rat lactating mammary gland: The role of cholesteryl ester hydrolase
Authors: Botham Kathleen M.
Published: November 2006

An acid cholesteryl ester hydrolase activity associated with a fraction containing mitochondria and lysosomes from rat lactating mammary glands was found to have a pH optimum of 5.0. Its sedimentation pattern was closely related to that of the lysosomal enzyme markers acid phosphatase and β‐glucuronidase, suggesting that the activity is associated with the lysosomes. The enzyme was strongly inhibited by Cu2+, but was inhibited little by other divalent metal ions. Acid cholesteryl ester hydrolase activity was almost completely abolished byp‐hydroxymercuribenzoate, but this effect was reversed in the presence of an equimolar concentration of reduced glutathione (GSH), indicating that the enzyme requires free sulfhydryl groups for activity. These properties are similar to those of acid, lysosomal cholesteryl ester hydrolases found in other tissues. Acid cholesteryl ester hydrolase activity was 8–14 fold higher in mammary tissue from lactating as compared to virgin rats. Neutral cholesteryl ester hydrolase activities associated with the microsomal and cytosolic subcellular fractions were also increased in lactating glands, but to a lesser extent. In addition, a 2‐fold increase in the activities of both the acid and microsomal neutral enzymes was seen during the first few days of lactation, while the cytosolic neutral activity remained constant. These results suggest that mammary gland cholesteryl ester hydrolases have a role in the regulation of cholesterol metabolism in mammary cells, and in the provision of cholesterol for secretion into milk.
Effects of perturbations in hepatic free and esterified cholesterol pools on bile acid synthesis, cholesterol 7α‐hydroxylase, HMG‐CoA reductase, acyl‐CoA:Cholesterol acyltransferase and cytosolic cholesteryl ester hydrolase
Authors: Grogan W. M. , Bailey M. L. , Heuman D. M. , Vlahcevic Z. R.
Published: November 2006

Effects of expansion of the hepatic free cholesterol pool on bile acid and cholesterol metabolism and homeostasis were examined in rats fed cholesterol in high‐fat diets or treated with oleyl‐p‐(n‐decyl)‐benzenesulfonate (ODS) or progesterone. Cholesterol feeding for 10–16 days, which increased free (33%) and esterified (6‐fold) cholesterol, had no effect on cholate synthesis, total bile acid synthesis, or cholate turnover, whereas these activities were increased 60–80% by ODS and progesterone, which produced only small increases (19%) in free cholesterol. Cholesterol feeding reduced β‐hydroxy‐β‐methylglutaryl (HMG)‐CoA reductase (72%) and cholesteryl ester hydrolase (48%) and increased acyl‐CoA:cholesterol acyltransferase (184%), whereas ODS and progesterone reversed these compensatory responses in cholesterol‐fed rats. Cholesterol 7α‐hydroxylase was changed no more than 22% by any treatment. A bolus of ODS elevated biliary cholesterol output 41% and shifted biliary bile acid synthesis and composition toward 12‐deoxy bile acids. These effects were not seen in ODS‐fed or progesterone‐treated rats, in which cholesteryl ester stores were depleted. It is concluded that effects of free cholesterol on bile acid synthesis and biliary cholesterol are probably mediated by specific precursor or regulatory pools which can be independently regulated and which represent a relatively small fraction of hepatic free cholesterol.
Free sterols, steryl esters, and lipid phosphorus in needles of scot's pine (Pinus sylvestris L.)
Authors: Fischer Christine , Höll Wolfgang
Published: November 2006

Free sterols, steryl esters, and lipid phosphorus were measured in new (current year) needles of Scot's pine during an annual cycle, and also in one‐, two‐, and three‐year‐old needles collected shortly after bud break. Sterols were identified and quantified by capillary gas chromatography and gas chromatography/mass spectrometry. Steryl esters were hydrolyzed enzymatically. Newly emerged needles contained highest amounts of free sterols and lipid phosphorus, probably reflecting increased membrane and organelle production, but low levels of steryl esters. Mature needles contained approximately equal amounts of free and esterified sterols. The molar phospholipid/free sterol ratio was 3∶1 at all the time periods studied. A dramatic increase of steryl esters was observed in the one‐, two‐, and three‐year‐old needles at times when new needles emerged. The individual free and esterified sterols were sitosterol, campesterol (presumably together with its C‐24 epimer), and cholesterol, at approximately 88, 10, and 2%, respectively. Isofucosterol, an intermediate in sitosterol biosynthesis, was present almost exclusively in newly emerged needles. Esterified sterols contained only trace amounts of isofucosterol. Shifts in favor of cholesterol and 24ζ‐methyl cholesterol occurred in the steryl esters during needle differentiation, and saturation grade of esterified fatty acids decreased. In mature needles, the composition of free sterols and steryl esters remained constant throughout the year.