bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gradient ford‐glucose and linoleic acid uptake along the crypt‐villus axis of rabbit jejunal brush border membrane vesicles
Authors: Fingerote R. J. , Doring K. A. , Thomson A. B. R. 
Published: November 2006

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

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

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

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

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

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

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

AbstractTo evaluate the effects of strain, gender and fasting in the regulation of lipoprotein lipase (LPL) and hepatic lipase (HL) activities were measured in tissues of male and female Wistar and Sprague‐Dawley rats after feeding or a 24‐h starvation period. It is noteworthy that an effect of gender on LPL activity was observed in Wistar, but not in Sprague‐Dawley rats, not in the basal (fed) activity in several tissues, such as white and brown adipose tissues, heart, and brain, but also in response to fasting which affected LPL activity in brown adipose tissue, heat and lung of female but not of male Wistar rats. By contrast, HL activity in liver, plasma and adrenals of Sprague‐Dawley rats was higher in females than in males. No effect of gender on HL activity was observed in Wistar rats. Our results indicate that differences exist between Wistar and Sprague‐Dawley rats in the regulation of both LPL and HL. Some of the contradictory results found in the literature may be explained by the differences between rat strains and gender, as well as differences in the nutritional status of the animals.
The influence of vitamin E and selenium on lipid peroxidation and aldehyde dehydrogenase activity in rat liver and tissue
Authors: Lee Hye‐Sung , Csallany A. Saari 
Published: November 2006

AbstractMalondialdehyde (MDA) production and cytosolic aldehyde dehydrogenase (ALDH) response were examined in rat liver tissues after feeding different levels of dietary vitamin E and/or selenium and polyunsaturated fat for 12–38 wk. MDA production was significantly increased by vitamin E deficiency or by high levels of polyunsaturated fat intake, but not by selenium deficiency. The activity of cytosolic ALDH increased upon increased production of MDA after 12–16 wk of feeding the lipid peroxidation‐inducing diets. However, ALDH activity was suppressed after 38 wk of feeding the vitamin E‐deficient diet. The results indicate that the hepatic cytosolic ALDH may be involved in the metabolism of MDA during a relatively short‐term increase inin vivo lipid peroxidation, but that ALDH activity becomes suppressed after more severein vivo lipid peroxidation has been produced. Hepatic and plasma α‐tocopherol levels and lipid peroxidation products were measured for the various dietary groups.
Meningioma phospholipid profiles measured by31P nuclear magnetic resonance spectroscopy
Authors: Seijo Luis , Merchant Thomas E. , van der Ven Leo T. M. , Minsky Bruce D. , Glonek Thomas 
Published: November 2006

AbstractFourteen cases of intracranial meningioma were characterized after chloroform/methanol extraction by31P nuclear magnetic resonance (NMR) spectroscopy at 202.4 MHz. Each phospholipid class detected in the extracts was identified and quantitated in terms of its molar percentage relative to the total phospholipids measured. The following phospholipids were assayed by31P NMR: phosphatidylglycerol, phosphatidic acid, diphosphatidylglycerol, ethanolamine plasmalogen, phosphatidylethanolamine (PE), lysophosphatidylinositol, phosphatidylserine, sphingomyelin, lysophosphatidylcholine (LPC), phosphatidylinositol (PI), sphingosylphosphorylcholine and phosphatidylcholine. In addition, two unidentified phospholipids were detected with resonances at 0.13 and −0.78 ppm, respectively. Three distinct types of spectra were obtained on the extracts and grouped accordingly for comparison purposes. Type 1 tumors showed unusual31P NMR profiles with low levels of PE and PI and elevated levels of LPC; type 2 tumors were characterized by low levels of the ethanolamine phospholipids and near equivalent levels of PI and LPC. The spectra of type 1 and type 2 tumors were characteristic of degenerative cells that lacked membrane permeability associated with loss of ethanolamine plasmalogen in the presence of significant phospholipid turnover. Meningiomas belonging to the third spectral type showed characteristics similar to those of normal tissues with normal levels of PE and ethanolamine plasmalogen, as well as very low levels of LPC relative to PI. Type 3 tumors lacked the characteristic signs of degeneration noted in type 1 and type 2 tumors. The data corroborate and augmentin vivo spectroscopic findings reported earlier and demonstrate the value of31P NMR spectroscopic phospholipid analysis on lipid extracts for the characterization of meningiomas.
The hypercholesterolemic effect of dietary coconut fatversus corn oil in hypo‐ or hyperresponsive rabbits is not exerted through influencing cholesterol absorption
Authors: Meijer G. W. , Lemmens A. G. , Versluis A. , Van Zutphen L. F. M. , Beynen A. C. 
Published: November 2006

AbstractIn two inbred strains of rabbits with high or low response of plasma cholesterol to dietary saturatedversus polyunsaturated fatty acids, the efficiency of intestinal cholesterol absorption was measured. The feeding of a cholesterol‐free purified diet containing saturated fatty acids in the form of coconut fat, when compared with a diet containing corn oil as polyunsaturated fatty acids, did not influence the efficiency of cholesterol absorption in the two rabbit strains. Irrespective of the dietary fat source, the hyperresponsive rabbits absorbed cholesterol more efficiently. It is concluded that the hypercholesterolemic effect of dietary coconut fatversus corn oil is not exerted by influencing cholesterol absorption.
Thermotropic phase properties of the hydroxyceramide/cholesterol system
Authors: Wiedmann Timothy S. , Salmon Amir 
Published: November 2006

AbstractThe interaction of cholesterol with ceramides containing α‐hydroxy fatty acyl chains (hydroxyceramides) has been studies as a foundation for characterizing the lipid bilayers of thestratum corneum. A relatively large quantity of cerebrosides was obtained from bovine brain and converted to ceramides through removal of the carbohydrate side chain. The ceramides were separated based on the absence or presence of hydroxy fatty acyl chains. The lyophilized hydroxyceramides showed a broad melting region at 92°C. Hydroxyceramides dispersed in water produced a relatively narrow, thermotropic transition at 75°C. The effect of cholesterol on this thermotropic phase transition of hydroxyceramides was determined by differential scanning calorimetry. With respect to the main transition, cholesterol caused a broadening of the phase transition at relatively low levels as well as a decrease in the peak transition temperature. The presence of cholesterol at levels in excess of 7 wt% gave rise to an additional low‐temperature transition at 55°C. Upon immediate rescanning, this transition was exothermic, but with increasing incubation time the area under the excess heat capacity curve as a function of temperature became smaller. After two days or more, the transition observed was endothermic. At cholesterol levels between 40 and 50 wt%, multiple peaks were observed. From comparisons with related systems, the cooperative thermal transitions of hydroxyceramides with cholesterol are suggested to result from changes in hydrogen bonding or be due to phase separation. The composition of isolated brain ceramides is being compared with that reported for thestratum corneum.
Lymphatic absorption of structured glycerolipids containing medium‐chain fatty acids and linoleic acid, and their effect on cholesterol absorption in rats
Authors: Ikeda Ikuo , Tomari Yoshiaki , Sugano Michihiro , Watanabe Soichiro , Nagata Junichi 
Published: November 2006

AbstractThe effects of various structured triglycerides containing medium‐chain (caprylic or capric acids) and long‐chain (linoleic acid) fatty acids on fatty acid and cholesterol absorption were studied in lymph‐cannulated rats. A considerable portion of capric and caprylic acid was absorbed through the lymph duct, although to a lesser extent than was linoleic acid. Capric and linoleic acid located at the 2‐position of 2‐decanoyl‐1,3‐dilinoleoyl‐glycerol (18∶2/10∶0/18∶2) and 2‐linoleoyl‐1,3‐didecanoyl‐glycerol (10∶0/18∶2/10∶0), respectively, tended to be absorbed more efficiently than those located at the 1‐ and 3‐position or those from tricaprin (10∶0/10∶0/10∶0) or trilinolein (18∶2/18∶2/18∶2). A similar trend was observed when the medium‐chain fatty acid was caprylic acid instead of capric acid. Caprylic acid absorption from 2‐octanoyl‐1,3‐dilinoleoylglycerol (18∶2/8∶0/18∶2) was significantly greater (p<0.05) than from 2‐linoleoyl‐1,3‐dioctanoyl‐glycerol (8∶0/18∶2/8∶0) or tricaprylin (8∶0/8∶0/8∶0). Preferential absorption of caprylic and linoleic acid was not observed when the 1 to 2 and the 2 to 1 mixtures of 8∶0/8∶0/8∶0 and 18∶2/18∶2/18∶2, respectively, were administered. The structured lipids did not affect the lymphatic absorption of cholesterol. The results suggest that structured triglycerides composed of medium‐chain fatty acids and linoleic acid may be more useful for the treatment of lipid malabsorption than are mixtures of medium‐chain triglyceride (MCT) and long‐chain triglycride (LCT).
Oxysterol incorporation into rat aorta resulting in elastin compositional changes
Authors: Blankenship J. W. , Van Gent C. M. , Sandberg L. B. , Roos P. J. , Scharffenberg J. A. 
Published: November 2006

AbstractThe incorporation of dietary cholestan‐3β, 5α, 6β‐triol (triol) into rat thoracic aortic tissue and changes in amino acid composition of the elastin were investigated to identify the cytotoxic properties of the triol. Weanling male Sprague‐Dawley rats were fed the following diets for three months: (i) normal chow, (ii) normal chow with 1% (w/w) cholesterol added, or (iii) normal chow with 0.9% (w/w) cholesterol and 0.1% (w/w) triol added. Triol levels in the blood and in the thoracic aortic tissue were measured. Compositional changes of elastin were also determined. After three months on the triol‐containing diet, triol was found in the thoracic aorta but was not detected in the blood. Amino acid analyses of the aortic tissue elastin revealed that the proline levels in the triol‐fed animals were significantly greater than in the other two diet groups, while the elastin levels of leucine, aspartate, arginine, and phenylalanine decreased significantly. The mechanism for these observed changes induced by triol may reflect alternate splicing of elastin messenger ribonucleic acid (mRNA) resulting in structural changes in the elastin molecule. Dietary triol does contribute to tissue triol content and is associated with aortic elastin compositional changes. How these changes may contribute to the development of cardiovascular disease is not known.