bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase properties of mixtures of ceramides
Authors: Han Chien‐Hsuan , Sanftleben Ronald , Wiedmann Timothy S. 
Published: November 2006

AbstractCeramides have been proposed to have a central role in the function of the stratum corneum. Ceramides also influence the phase properties of model skin lipid mixtures, but the relevance of this to the stratum corneum function is controversial. Because the stratum corneum contains several classes of ceramides, the type of ceramides used in model mixtures of stratum corneum lipid lamellae may be important. Thus, the properties of α‐hydroxy fatty acid containing (HFAC) and nonhydroxy fatty acid containing (NFAC) ceramides and their mixtures have been investigated. Ceramides were obtained by the conversion of purified bovine brain cerebrosides. Isolated, anhydrous HFAC underwent an endothermic solid to liquid transition at 92°C. With hydration, an endothermic transition at 71.8°C was observed which was accompanied by a reduction in the birefringence. The enthalpy increased from 66 to 89 J/g with a 20‐d storage time. These thermal properties are very similar to those observed with hydroxy fatty acid containing cerebrosides. In contrast, anhydrous nonhydroxy fatty acid containing ceramides underwent a broad endothermic transition over the temperature range of 50–90°C. When hydrated, the initial endothermic transition was interrupted by an exothermic transition that was followed immediately by a second endothermic transition. During these thermal changes, there was a loss of birefringence, and with completion of the second endothermic transition, a nonbirefringent liquid was observed. NFAC samples, stored at 70°C for 5 min, cooled, and then rescanned, displayed only one endotherm at 75°C. The thermal behavior of mixtures of HFAC and NFAC was relatively simple, with a progressive decrease and broadening in the temperature of the phase transition as the proportion of NFAC increased up to weight fractions of NFAC of 0.7. At lower weight fractions, a plateau in thetransition temperature as a function of weight fraction was observed. Even at a weight fraction of 0.1 HFAC, no transition to a nonbirefringent liquid state was observed. The high enthalpic changes observed with mixtures of HFAC and NFAC are consistent with the proposed central role that ceramides have in the mechanical and permeability properties of the skin. Moreover, the marked difference in the properties of these two similar lipids may help to explain some of the properties of the stratum corneum.
Effect of exercise on the plasma nonesterified fatty acid composition of dogs and goats: Species with different aerobic capacities and diets
Authors: McClelland Grant , Zwingelstein Georges , Taylor C. Richard , Weber Jean‐Michel 
Published: November 2006

AbstractThe goals of this study were to determine: (i) whether mammals mobilize particular nonesterified fatty acids (NEFA) preferentially during locomotion, (ii) if differences in aerobic capacity or diet can affect the pattern of NEFA mobilization and (iii) which individual NEFA are most representative of total NEFA concentration changes, to use them as tracers for turnover studies. Individual NEFA were measured in trained dogs and goats (VO2max dog/VO2max goat=2.2; where VO2max=max‐imal oxygen consumption) during treadmill exercise at 40 and 60% VO2max. Important interspecies differences in individual NEFA concentrations could be attributed to differences in aerobic capacity. The more aerobic species (dog) had much higher plasma NEFA concentrations for all but one NEFA (18∶0), when compared with the low‐aerobic species (goat). In addition, exercise caused a large increase in concentration of individual NEFA in the dogs, with the largest increases seen in 18∶1 (150% above resting values) and 16∶0 (60% increase), but it had no effect in goats. Therefore, the aerobic species has a much higher ability for mobilizing and transporting NEFA in plasma than its low‐aerobic counterpart. Two NEFA accounted for more than half total plasma NEFA in both species, 18∶1 (about 35% total NEFA) and 16∶0 (20%). Calculation of variability in percent composition reveals that oleate and palmitate also closely reflect changes in total NEFA and are therefore the most appropriate tracers forin vivo kinetic studies in exercising mammals. Differences in diet and digestion physiology explained some differences in the plasma NEFA composition of the two species; this was reflected in the percent contributions of individual fatty acids to total NEFA: in dogs 18∶1>16∶0>18∶2>18∶0, while in goats 18∶1>16∶0>18∶0>18∶2. Also, only goats had 18∶3 (6% total NEFA), a fatty acid of plant origin, while only dogs had 16∶1 (7% total NEFA). Overall, however, the plasma NEFA composition of goats did not exactly reflect that of their diet due to preabsorptive modification of unsaturated fatty acids, while in dogs there was a good correlation between dietary and plasma NEFA.
Dietary oligofructose lowers triglycerides, phospholipids and cholesterol in serum and very low density lipoproteins of rats
Authors: Fiordaliso Maria , Kok Nadine , Desager Jean‐Pierre , Goethals Fabienne , Deboyser Dominique , Roberfroid Marcel , Delzenne Nathalie 
Published: November 2006

AbstractThe present study was aimed at answering the question why feeding rats an oligofructose (OFS) supplemented diet could cause a significant reduction in plasma lipid levels. Daily administration of a 10% (w/w) OFS‐containing diet to normolipidemic male rats resulted in a decrease in plasma triglycerides, phospholipids and cholesterol. The triglyceride‐lowering effect was observed after one week and lasted for at least 16 wk and was associated with a reduction in plasma very low density lipoproteins, indicating that the hypolipidemic effect of OFS may be due to changes in liver lipid metabolism. We therefore tested whether OFS feeding modified the capacity of the liver to synthesize triglycerides from free fatty acids. Hepatocytes isolated from livers of control and OFS‐fed rats were incubated in the presence of [1‐14C]palmitate, and both intracellular and extracellular [14C]triglyceride formation were quantified. We found that chronic feeding of an OFS‐supplemented diet to rats significantly reduced the capacity of isolated hepatocytes to synthesize triglycerides from palmitate. The results suggest that, like other soluble dietary fibers, OFS significantly alters liver lipid metabolism, resulting over time in a significant reduction in plasma triglyceride, phospholipid and cholesterol levels.
Incorporation ofall‐trans‐or 9‐cis‐β‐carotene into mixed micellesin vitro
Authors: Levin Galit , Mokady Shoshana 
Published: November 2006

AbstractVarious studies suggest thatall‐trans‐ and 9‐cis‐β‐carotene are absorbed in the intestine to different extents. The present study was undertaken to evaluate the degree ofin vitro incorporation of the two isomers into intestinal mixed micelles, which is an essential early step in the absorption process. The micelles were designed to simulate those present during fat digestion in the lumen of the human small intestine with respect to bile salts, lipids, pH and temperature. Solutions ofall‐trans‐and 9‐cis‐β‐carotene at various ratios were added to the lipid mixture. A direct correlation was seen between the 9‐cis‐β‐carotene level in the mixture and the degree of total β‐carotene incorporation into micelles. An increased level ofall‐trans‐β‐carotene incorporated into the micelles. In contrast, when carotene mixtures enriched with the 9‐cis isomer were used, an increase in the level of total carotene in the solution was accompanied by a constant or even enhanced carotene incorporation. The results indicate that the differences in the absorption of β‐carotene isomers might be the result of their different ability to be incorporated into the lipid micelles of the intestinal lumen. In addition, the results point toward the possibility that ingestion of 9‐cis‐β‐carotene by humans may increase carotene availability.
Comparison of fatty acid α‐oxidation by rat hepatocytes and by liver microsomes fortified with NADPH, Fe3+ and phosphate
Authors: Huang Shewen , Van Veldhoven Paul P. , Asselberghs Stanny , Eyssen Hendrik J. , de Hoffmann Edmond , Mannaerts Guy P. 
Published: November 2006

AbstractRat liver microsomes, when fortified with NADPH, Fe3+ and phosphate, can catalyze the oxidative decarboxylation (α‐oxidation) of 3‐methyl‐substituted fatty acids (phytanic and 3‐methylheptadecanoic acids) at rates that equal 60–70% of those observed in isolated hepatocytes (Huang, S., Van Veldhoven, P.P., Vanhoutte, F., Parmentier, G., Eyssen, H.J., and Mannaerts, G.P., 1992,Arch. Biochem. Biophys. 296, 214–223). In the present study we set out to identify and compare the products and possible intermediates of α‐oxidation formed in rat hepatocytes and by rat liver microsomes. In the presence of NADPH, Fe3+ and phosphate, microsomes decarboxylated not only 3‐methyl fatty acids but also 2‐methyl fatty acids and even straight chain fatty acids. The decarboxylation products of 3‐methylheptadecanoic and palmitic acids were purified by highperformance liquid chromatography and identified by gas chromatography/mass spectrometry as 2‐methyl‐hexadecanoic and pentadecanoic acids, respectively. Inclusion in the incubation mixtures of glutathione plus glutathione peroxidase inhibited decarboxylation by more than 90%, suggesting that a 2‐hydroperoxy fatty acid is formed as a possible intermediate. However, we have not yet been able to unequivocally identify this intermediate. Instead, several possible rearrangement metabolites were identified. In isolated rat hepatocytes incubated with 3‐methylheptadecanoic acid, the formation of the decarboxylation product, 2‐methylhexadecanoic acid, was demonstrated, but no accumulation of putative intermediates or rearrangement products was observed. Our data do not allow us to draw conclusions on whether the reconstituted microsomal system is representative of the cellular α‐oxidation system. However, the results we obtained with [3‐3H]‐labelled fatty acids indicate that during α‐oxidation in intact cells the hydrogen at carbon‐3, which carries the methyl branch, is not attacked.
Lipid composition of glucose‐stimulated pancreatic islets and insulin‐secreting tumor cells
Authors: Rustenbeck Ingo , Matthies Alexander , Lenzen Sigurd 
Published: November 2006

AbstractThe effect of glucose stimulation (25 mM for 5 min) on the phospholipid and neutral lipid composition of isolated pancreatic islets was studied to find out whether there is a change in the mass of potential lipid mediators or modulators of insulin secretion. For comparison, the lipid compositions of homogenates and subcellular fractions from RINm5F insulin‐secreting tumor cells and of glucose‐stimulated streptozotocin/nicotinamide‐induced islet cell tumors were analyzed. After separation of the lipid extract into a neutral and an acidic fraction by anion‐exchange chromatography, lipids were separated by high‐performance thin‐layer chromatography and quantitated byin situ densitometry of the cupric sulfate‐charred bands. In glucose‐stimulated islets, the molar percentages of phosphatidic acid (PA) and of phosphatidylinositol were significantly increased (3.1 vs. 4.7 mol% and 8.6 vs. 11.8 mol%), while those of all other phospholipids and neutral lipids, including 1,2‐diacylglycerol, were not significantly changed. In stimulated islet cell tumors, an increase of PA was visible in the microsomal fraction, and there was an increase of lysophosphatidylcholine in the mitochondrial fraction. However, in both tumoral tissues, particularly in RINm5F cells, the lipid distribution pattern showed abnormalities which can be regarded as a loss of differentiation and which limit the usefulness of these tissues for the study of the physiological regulation of lipid metabolism during glucose stimulation. In conclusion, the data are in accordance with a role of PA early in stimulus‐secretion coupling. The well‐known stimulation of phospholipid synthesis in pancreatic islets during glucose‐induced insulin secretion does not result in an increase in the total phospholipid mass.
Effect of dietary fat on colonic protein kinase C and induction of aberrant crypt foci
Authors: Lafave Lynne M. Z. , Kumarathasan Prem , Bird Ranjana P. 
Published: November 2006

AbstractA major objective of the present study was to determine whether a high‐fat diet affects early events during colon carcinogenesis. Female Sprague‐Dawley rats were injected with saline or azoxymethane (20 mg/kg) and fed either a normal (5% corn oil w/w) or a high (5% corn oil and 15% beef tallow w/w) fat diet. To assess the effect of a known tumor‐promoting diet on the early events of neoplastic transformation, Study 1 examined the induction and growth of aberrant crypt foci (ACF) as well as of proliferative indices. The total number of ACF were similar in both groups even after 8 wk of dietary treatment; however, ACF with accelerated growth characteristics (≥4 crypts/focal lesions) were more prevalent (P≤0.05) in the colons of animals fed the high‐fat diet. Metaphase arrest cells and 5′‐bromo‐2′‐deoxyuridine labelled cells showed no appreciable response to dietary changes. To determine whether changes in colonic signal transduction pathways represent an early response to dietary modification, Study 2 evaluated the activity of protein kinase C (PKC), proliferative indices and changes in phospholipid fatty acid profiles. In comparison to the normal fat group, the colons of high‐fat fed animals exhibited higher (P≤0.05) membranes and lower soluble PKC activity; however, proliferation patterns of these colons were not altered. Changes in the membrane lipid composition were minor; however, an increase in the phosphatidylcholine/phosphatidylethanolamine ratio and in 20∶4n−6 was noted. Our results demonstrate that in comparison to a normal‐fat diet, a high‐fat diet stimulated the growth of a population of ACF, i.e., preneoplastic lesions leading to advanced growth characteristics. In addition, a high‐fat diet exerted a marked influence on total, cytosolic and membrane associated PKC activities. The findings suggest that modulation of PKC may play a critical role at the early stages of colon carcinogenesis.
Apolipoprotein A‐I, A‐IV and E synthesis in the liver of copper‐deficient rats
Authors: Nassir Fatiha , Mazur Andrzej , Gueux Elyett , Sérougne Colette , Rayssiguier Yves 
Published: November 2006

AbstractCopper deficiency induces hypercholesterolemia in the rat. This hypercholesterolemia is mainly due to an increase in apo E‐rich high density lipoproteins (HDL1). The present study was undertaken to determine whether the HDL increase could be explained by altered low‐molecular weight apolipoprotein (apo) synthesis in the liver. The effect of copper deficiency on apo A‐I, apo A‐IV and apo E concentrations in plasma, as well as on respective mRNA levels and synthesis in the liver, were therefore investigated. We observed that the increased HDL1 levels in the plasma of copper‐deficient rats were associated with a significant rise in plasma apo E concentrations; however, plasma apo A‐I and apo A‐IV concentrations remained unchanged. Liver apo synthesis and respective apo mRNA levels were not significantly altered in copper‐deficient animals when compared to control rats. No changes in apo E mRNA levels in various tissues from copper‐deficient, as compared to control rats, were noted. Based on the data obtained, it was concluded that the observed changes in plasma lipoprotein and apo concentrations are not related to changes in low‐molecular weight apo synthesis in the liver. The mechanisms of the impaired catabolism of HDL1 should be further evaluated to possibly explain the observed increase in this fraction in copper‐deficient rats.
Recommendations for the use of species diversity indices with reference to a recently published article as an example
Authors: Itô Yosiaki 
Published: November 2006

AbstractThere are some recommendations for the use of species diversity indices in a paper recently published in this journal by M. Ohsawa on the species richness and composition of weevils in five forest types in the middle region of Japan. Because several factors, such as small sample size, calculation of Simpson's diversity index by the use of the original equation of Simpson's measure of concentration D, and a weak point in the Shannon–Wiener diversity index H′, may have led to biased estimates, I recalculated these indices using combined species diversity values of the five forest types. As the general tendencies of 1−D and H′ values calculated here were similar to those in Ohsawa's paper, there is no need to propose any change to his view. However, these recalculated diversity indices indicated that they are values which are more suitable for use. It should be noted that the characteristics and weak point associated with the diversity indices need to be taken into account in future studies.
Thermal decomposition as route for silver nanoparticles
Authors: Navaladian S. , Viswanathan B. , Viswanath R. P. , Varadarajan T. K. 
Published: November 2006

Abstract
Single crystalline silver nanoparticles have been synthesized by thermal decomposition of silver oxalate in water and in ethylene glycol. Polyvinyl alcohol (PVA) was employed as a capping agent. The particles were spherical in shape with size below 10 nm. The chemical reduction of silver oxalate by PVA was also observed. Increase of the polymer concentration led to a decrease in the size of Ag particles. Ag nanoparticle was not formed in the absence of PVA. Antibacterial activity of the Ag colloid was studied by disc diffusion method.
Discriminating power of the hydrocarbon content from virgin olive oil of extremadura cultivars
Authors: Bueno Emilio Osorio , Casas Jacinto Sánchez , García Alfonso Montaño , González Lourdes Gallardo 
Published: November 2006

AbstractSamples of virgin olive oils (105) from seven Extremaduran olive varieties (Cacereña, Carrasqueña, Cornezuelo, Corniche, Morisca, Picual, and Verdial de Badajoz) in three stage of maturity (green, semi‐ripe, and ripe) were collected and the alkane, alkene, and sesquiterpene contents determined. There were significant differences at the 0.01 probability level in most of the hydrocarbons, both by variety and by state of maturity. Discriminant analysis applied to 70 samples explained 72.3% of the variance between the different groups of varieties and allowed 90% of the samples to be classified according to their variety. The acceptability of the model was verified against the remaining 35 samples, giving a mean level of correct classification of 94%.
A comparative study of fatty acid profiles of Passiflora seed oils from Uganda
Authors: Nyanzi Steven A. , Carstensen Bernd , Schwack Wolfgang 
Published: November 2006

AbstractA comparative study is presented of the FA composition (FAC) of the seed oils from the yellow passion fruit Passiflora edulis Sims var. flavicarpa (I), the purple fruit Passiflora edulis Sims var. edulis (II), the purple Kawanda hybrid, which is a cross between I and II (III), and the light‐yellow apple passion fruit Passiflora maliformis L. (IV) grown in Uganda. Oil yields from the four varieties were between 18.5 and 28.3%. A GC analysis of the oils showed the most dominant FA to be linoleic (67.8–74.3%), oleic (13.6–16.9%), palmitic (8.8–11.0%), stearic (2.2–3.1%), and α‐linolenic (0.3–0.4%) acids. The unsaturated FA content in the oils was high (85.4–88.6%). Iodine values of the seed oils of I, II, III, and IV calculated from the FAC were 133, 141, 133, and 138, respectively. The FAC and the iodine value of the seed oil in III are distinctly closer to the rootstock (I) than the scion (II). This indicates that the rootstock influence on the FAC of passion fruit seeds is graft‐transmissible. The study further confirms that passion fruit seed oils represent a good source of essential unsaturated FA.
Olive oil microemulsions as a biomimetic medium for enzymatic studies: Oxidation of oleuropein
Authors: Papadimitriou V. , Sotiroudis T. G. , Xenakis A. 
Published: November 2006

AbstractMicroemulsions consisting of olive oil as the non‐polar solvent, lecithin as surfactant, 1‐propanol as cosurfactant, and water were prepared. The choice of the compositions of the microemulsions used was based on the pseudo‐ternary phase diagrams of the system determined at 30°C, for different weight ratios of lecithin/olive oil. Lecithin solubilization and water incorporation in these microemulsion systems was limited. Tyrosinase, an oxidizing enzyme present in olives, was successfully incorporated in the water core of these microemulsions. Enzymatic oxidation of oleuropein, the most abundant olive phenolic compound, in the restricted aqueous environment of olive oil microemulsions was studied. Formation of oleuropein oxidation products was followed spectrophotometrically at 30°C for several minutes. An absorption maximum was observed at 415 nm. When the enzymatic reaction was considered at different tyrosinase and oleuropein concentrations, a rapid inactivation of the enzyme was observed. Addition of l‐proline as a coupling reactor did not succeed in preventing enzyme inactivation in the microemulsions, probably owing to substrate localization and product accumulation around the entrapped enzyme molecules in the micellar interface.
Thermal properties and adhesiveness of soy protein modified with cationic detergent
Authors: Wang Y. , Wang D. , Sun X. S. 
Published: November 2006

AbstractThis research studied the effects of cationic detergents on the adhesiveness and thermal properties of soy protein isolate (SPI). Three cationic detergents, hexadecyltrimethyl ammonium bromide, ethylhexadecyldimethyl ammonium bromide (EDAB), and benzyldimethylhexadecyl ammonium chloride, each at concentrations of 1.3, 2.6, 5.2, and 7.8 mM, were used to modify SPI. The effect of pH at selected EDAB concentrations was also studied. Results showed that both detergent concentration and pH had significant effects on the adhesiveness of modified SPI. SPI modified with detergent at a concentration of 2.6 mM yielded the greatest dry tensile strength and water resistance, which indicated that a moderate protein denaturation might be favorable to the adhesion of SPI. Both modified and unmodified SPI showed greater adhesive strength at their optimal pH values. Modified SPI showed greatest adhesive strength at pH 7, whereas unmodified SPI showed greatest adhesive strength at pH 4.5; the tensile strength of modified SPI was greater than that of unmodified SPI. The protein‐denaturation temperature and the enthalpy of modified SPI adhesives were also analyzed by using DSC. Denaturation of the native structure of SPI increased as detergent concentration increased.
Crystal morphology, microstructure, and textural properties of model lipid systems
Authors: Shi Yuping , Liang Baomin , Hartel Richard W. 
Published: November 2006

AbstractMixtures of model lipid systems containing high‐melting and low‐melting lipid classes were crystallized and microscope images obtained for analysis of crystal morphology and microstructure. Rheological properties of these semisolid systems were tested by use of a texture analyzer. The nature of the highmelting component in a mixture dominated the crystal morphology and, combined with interactions between crystalline and liquid materials, resulted in different microstructures that influenced the rheological properties. In addition to size, shape, and amount (solid fat content) of crystalline material, the crystal packing density, representing how densely the crystalline particles in every level (individual, aggregate, or floc) were arranged, and the nature (or strength) of the link (or bridge) connecting the crystalline particles were important microstructural factors to determine rheological properties. Depending on different crystal packing densities and linking bridges, two different systems were identified in terms of microstructure type—mobile and immobile—in which the relative mobility of microstructural components had different levels. These mobility levels led to different rheological responses.