bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phase behavior of laundry surfactants in polar solvents
Authors: Stuart Marc C. A. , Van de Pas John C. , Engberts Jan B. F. N. 
Published: November 2006

AbstractLaundry surfactants are usually mixtures of ionic and nonionic detergents that exhibit a complex phase behavior. Here the ternary phase behavior of an isotropic and a liquid crystalline (LC) surfactant mixture has been examined in water/solvent systems. The size of the LC area in the ternary phase diagram was correlated to solvent parameters including the dielectric constant and the Gordon cohesiveness parameter. The Gordon parameter was found to have a linear relationship with the amount of solvent needed to go from an LC to an isotropic state over a wide range of solvents from polar to apolar. For solvents in which no surfactant aggregation (micellar or inverted micellar) is expected, the size of the LC area is linear with the reciprocal of the dielectric constant of the solvent. On diluting practical detergent liquids with water, a large LC area can be avoided by using solvents with a relatively low dielectric constant and with a relatively low molecular weight.The aggregated state of the surfactant mixtures in the isotropic regions of the phase diagram was studied using the solvatochromic fluorescent probe Nile Red. In the water corner of the phase diagram, the surfactants are aggregated into micelles. In strongly polar solvents, such as glycerol, ethylene glycol, formamide, and ethanolamine, the surfactants are also aggregated into micelles. In somewhat less polar solvents, such as methanol, ethanol, and t‐butanol, the surfactant molecules are randomly distributed. In the surfactant‐rich corner of the phase diagram of the isotropic mixture, the surfactant forms inverted micelles. An inverted micelle‐to‐micelle transition could be observed on dilution in ethylene glycol as a discontinuity in the trend of the Nile Red fluorescence maxima.
Alkyl polyglucosides as hydrotropes
Authors: Matero Anna , Mattsson Åsa , Svensson Martin 
Published: November 2006

AbstractThe hydrotropic effect of different alkyl polyglucosides (APG) has been studied and compared with a model hydrotrope, toluol‐4‐sulfonic acid. The effect has been assessed by two different methods: (i) as the cloud point elevation of a solution containing different nonionic surfactants upon addition of the hydrotrope and (ii) the destabilization of liquid crystaline phases in a ternary system. The effect of the hydrophobic alkyl group length was found to be opposite in the two methods. APG with intermediate alkyl chain lengths (octyl and decyl) was shown to be very effective in elevating the cloud point, while APG with a short (butyl) group was the most efficient in destabilizing liquid crystalline phases in the system of water, sodium dodecyl sulfate and pentanol. Effects on phase behavior and cloud point elevation with addition of an APG are highly dependent on its structure. However, the correlation between structural effects, as observed in the two methods requires further study.
Solubilization of model stratum corneum liposomes by quaternary ammonium surfactants
Authors: de la Maza A. , Coderch L. , Lopez O. , Gonzalez P. , Baucells J. , Parra J. L. 
Published: November 2006

AbstractThe solubilizing interactions of a series of quaternary ammonium surfactants [alkyl chain lengths C‐12 (DoTAB), C‐14 (TeTAB), and C‐16 (HeTAB)] with liposomes formed by a mixture of lipids modeling the stratum corneum (SC) lipid composition (40% ceramides, 25% cholesterol, 25% palmitic acid, and 10% of cholesteryl sulfate) were investigated. Surfactant/lipid molar ratios (Re) and bilayer/aqueous phase partition coefficients (K) were determined by monitoring changes in static light scattering of the system during solubilization. Free surfactant concentration was always similar to the critical micelle concentration (CMC). A general assumption for phosphatidylcholine (PC) liposomes suggests that the free surfactant concentration must reach CMC for solubilization to occur. This assumption can be applied to SC liposomes in this study, and indicates that liposome solubilization was mainly driven by mixed micelle formation. The Re and K parameters fell as the surfactant alkyl chain length decreased or CMC increased. Thus, a higher CMC corrsponds to an increased ability of these surfactants to saturate or solubilize SC liposomes and to a lower degree of partitioning into liposomes or affinity with these bilayer structures. The overall balance of these opposing tendencies shows that TeTAB had the highest effectiveness with respect to the saturation and solubilization of SC structures in terms of total surfactant needed to produce these effects. Different trends in surfactant interaction with SC liposomes were observed when comparing Re and K parameters with those for PC liposomes. Because SC liposomes were more resistant to the surfactant action, the affinity of surfactants with these bilayer structures was higher in all cases.
Pyrimidinium cationic surfactants as emulsifiers for oil‐in‐water emulsions
Authors: Pegiadou‐Koemtjopoulou S. , Tsatsaroni E. , Mylona M. 
Published: November 2006

AbstractPyrimidinium cationic surfactants with 13–17 carbon atoms in the hydrophobe were used as emulsifiers for oil‐inwater (heptane/water) emulsions at concentrations near the critical micelle concentrations. Interfacial tensions of the emulsifier solutions in water against heptane were measured. Drop size distributions of the emulsions were determined at different times using microscopic techniques, and the rate of coalescence was calculated. The structure having 16 carbon atoms in the alkyl chain had coalescence rates lower than the other structures, including two conventional C‐16 cationics used as controls.
Use of low‐temperature differential scanning calorimetry for determination of ethylene oxide content in some nonionic surfactants
Authors: Rao V. Mohan , Uma S. , Gajelli C. G. , Kelkar Ravi Y. 
Published: November 2006

AbstractLow‐temperature differential scanning calorimetry studies on ethoxylates of hydrogenated castor oil and 12‐hydroxystearic acid show endothermic transformations that could be ascribed to melting of ethylene oxide (EO) components of the surfactant molecule. The ethoxylation process also results in formation of free polyethylene glycol (PEG). Separation of free PEG followed by area under the curve measurements enabled estimation of EO content of the product formed during manufacture. The melting endotherm provided additional information on the chain‐length distribution of polyoxyethylene units in the surfactant.
Critical micelle concentrations of ternary surfactant mixtures: Theoretical prediction with user‐friendly computer programs and experimental design analysis
Authors: Coret J. , Shiloach A. , Berger P. , Blankschtein D. 
Published: November 2006

AbstractWe studied the behavior of an aqueous ternary surfactant mixture composed of a nonionic surfactant and two anionic surfactants which differ in both surfactant hydrophobic tail length and surfactant hydrophilic head structure. We used an experimental design program to calculate the critical micelle concentrations (CMCs) of this ternary surfactant mixture over the entire range of solution compositions. As inputs, the experimental design methodology requires the values of the ternary surfactant mixture CMCs for a limited subset of solution compositions which is determined by the experimental design program. We showed that this subset of ternary surfactant mixture CMC values can either be measured experimentally or predicted theoretically. The theoretical CMCs were predicted by a series of userfriendly computer programs which are based on molecular‐ther‐modynamic theories describing single and mixed micelle formation. The experimental design program generated two surfaces describing the ternary surfactant mixture CMCs over the entire solution composition range—one based on the experimentally measured subset of CMC values, and the other based on the theoretically predicted CMC values for the same subset of solution compositions. We found that these two CMC surfaces agree very well, thus demonstrating the utility of the computerassisted molecular‐thermodynamic modeling as a predictive tool in surfactant mixture characterization and design.
Adsorption behavior of surfactant‐polyacrylamide mixtures with kaolin
Authors: Sastry N. V. , Dave P. N. 
Published: November 2006

AbstractThe adsorption behavior of three surfactants—hexadecylpyridinium bromide (HPyBr), sodium dodecylbenzene sulfonate (SDBS), and Triton X‐100 (TX‐100)—on kaolin from aqueous solution is monitored as a function of pH. The nature and shape of the adsorption isotherms are typical and highly dependent on the surfactant structure. All three surfactants adsorb on kaolin beyond the limits of monolayer coverage. Isotherms for HPyBr fit the Langmuir equation well. SDBS isotherms are typical of a two‐stage process, and TX‐100 adsorption isotherms are S‐shaped. The pH‐sensitive adsorption of each surfactant and the models used to represent the isotherms are considered together in explaining the mechanism of adsorption in each case. The complex mixture adsorption behavior from polyacrylamide‐surfactant mixtures is also determined in acidic and basic pH media. Three polyacrylamides, catam1, anam1 and nonam1, are chosen to represent cationic, anionic, and nonionic polymers, respectively. Both competitive and synergistic effects are noted in the mixture adsorption depending upon the polymer‐surfactant pair and the mode of introduction of a second component in the presence of another. The results are explained by considering various factors such as changes in the nature of solvent power of the media, interaction between the polymer and surfactant in the bulk solution as well as at the kaolin surface, blocking of surface sites by a preadsorbed component, and the change in the conformation state of polymer chains
Metabolism of very long chain polyunsaturated fatty acids in isolated rat germ cells
Authors: Retterstøl Kjetil , Tran Thien N. , Haugen Trine B. , Christophersen Bjørn O. 
Published: November 2006

AbstractWhich cell type is responsible for the high levels of very long chain polyunsaturated fatty acids in testis and whether this fatty acid pattern is a result of a local synthesis are not presently known. In this study, fatty acid conversion from 20∶4n−6 to 22∶5n−6 and from 20∶5n−3 to 22∶6n−3 was investigated in isolated rat germ cells incubated with [1‐14C]‐labeled fatty acids. The germ cells elongated the fatty acids from 20‐ to 22‐carbon atoms and from 22‐ to 24‐carbon atoms but had a low Δ6 desaturation activity. Thus, little [14C]22∶5n−6 and [14C]22∶6n−3 were synthesized. When Sertoli cells were incubated with [1‐14C]20∶5n−3 for 24 h, an active fatty acid elongation and desaturation were observed. In vivo germ cells normally have a higher content of 22∶5n−6 or 22∶6n−3 than Sertoli cells. An eventual transport of essential fatty acids from Sertoli cells to germ cells was thus studied. Different co‐culture systems were used in which germ cells were on one side of a filter and Sertoli cells on the opposite side. When isolated pachytene spermatocytes or round spermatids were added to the opposite side of a semipermeable filter, approximately 1 nmol [14C]‐22∶6n−3 crossed the filter. Little of this was esterified in the germ cells. Similarly, in using [1‐14C]20∶4n−6 in identical experiments, very little [14C]22∶5n−6 was esterified in germ cells on the opposite side of the filter. Although the very active synthesis of 22∶5n−6 and 22∶6n−3 observed in Sertoli cells suggests a transport of these compounds to germ cells, this was not experimentally determined.
Composition of the silk lipids of the spider Nephila clavipes
Authors: Schulz Stefan 
Published: November 2006

AbstractA detailed analysis of the lipids of spider silk is given for the first time. Extracts of the silk from the golden orb weaver, Nephila clavipes, were studied by gas chromatography, mass spectrometry, and chemical derivatizations. The major group of the lipids consisted of methyl‐branched 1‐methoxyalkanes (methyl ethers) with up to four methyl groups in the chain (chain length between C28 and C34), which are unique to spiders. The position of the methyl branches was determined by conversion into cyanides, which allowed easy location of methyl branches. The second‐largest group included alkanes with a wide structural variety; 2‐methyl‐branched, even‐numbered hydrocarbons predominated. A general numerical method for the estimation of retention indices of alkanes and their derivatives is presented. Further components of the web included alkanols and alkanediols, fatty acids, and glyceryl ethers. Some comments on the biosynthesis of these compounds are also given.
Intestinal apolipoprotein B secretion is inhibited by the flavonoid quercetin: Potential role of microsomal triglyceride transfer protein and diacylglycerol acyltransferase
Authors: Casaschi Adele , Wang Qi , Dang Ka'ohimanu , Richards Alison , Theriault Andre 
Published: November 2006

AbstractRecent studies have yielded evidence that plant flavonoids reduce hepatic lipid and apolipoprotein B (apoB) secretion. However, the possible role of flavonoids in regulating lipid and apoB secretion by the intestine has not been studied. The purpose of our study was to examine the effects of quercetin, a common dietary flavonoid, on TAG and apoB secretion in a human intestinal cell‐line, CaCo‐2. Differentiated postconfluent CaCo‐2 cells grown on filters and pretreated with quercetin for 8 h were shown by ELISA to inhibit basolateral apoB secretion in a dose‐dependent manner. At 15 μM, the secretion of both apoB‐100 and apoB‐48 were inhibited similarly. This effect was shown to be specific, as quercetin did not affect the incorporation of [35S]methionine/cysteine into secreted TCA‐precipitable proteins. To determine the mechanism underlying this inhibitory effect, we examined two regulatory points: IAG availability and lipid transfer to the lipoprotein particle. Quercetin inhibited TAG synthesis under both basal and lipid‐rich conditions, indicating that lipid availability is a determining factor in the regulation of apoB secretion by quercetin. The reduction was due at least in part to a decrease in diacylglycerol acyltransferase activity. We next examined lipid transfer or lipidation of the lipoprotein particle by analyzing microsomal IAG transfer protein (MTP) activity. Quercetin decreased MTP activity moderately. In summary, the data demonstrated that pharmacological concentrations of quercetin are a potent inhibitor of intestinal apoB secretion and that reduced lipid availability and lipidation in the lipoprotein assembly step are the mechanism for the suppression of apoB‐containing lipoprotein secretion by quercetin in CaCo‐2 cells.
Comparative effects of palm vitamin E and α‐tocopherol on healing and wound tissue antioxidant enzyme levels in diabetic rats
Authors: Musalmah M. , Nizrana M. Y. , Fairuz A. H. , NoorAini A. H. , Azian A. L. , Gapor M. T. , Wan Ngah W. Z. 
Published: November 2006

AbstractThe effect of supplementing 200 mg/kg body weight palm vitamin E (PVE) and 200 mg/kg body weight α‐tocopherol (α‐loc) on the healing of wounds in streptozotocin‐induced diabetic rats was evaluated. The antioxidant potencies of these two preparations of vitamin E were also evaluated by determining the antioxidant enzyme activities, namely, glutathione peroxidase (GPx) and superoxide dismutase (SOD), and malondialdehyde (MDA) levels in the healing of dermal wounds. Healing was evaluated by measuring wound contractions and protein contents in the healing wounds. Cellular redistribution and collagen deposition were assessed morphologically using cross‐sections of paraffin‐embedded day‐10 wounds stained according to the Van Gieson method. GPx and SOD activities as well as MDA levels were determined in homogenates of day‐10 dermal wounds. Results showed that PVE had a greater potency to enhance wound repair and induce the increase in free radical‐scavenging enzyme activities than α‐Toc. Both PVE and α‐Toc, however, were potent antioxidants and significantly reduced the lipid peroxidation levels in the wounds as measured by the reduction in MDA levels.
9‐trans,11‐trans‐CLA: Antiproliferative and proapoptotic effects on bovine endothelial cells
Authors: Lai Kuan‐Lin , Torres‐Duarte Armida P. , Vanderhoek Jack Y. 
Published: November 2006

AbstractEndothelial cell function can be influenced by nutrition, especially dietary FA and antioxidants. One class of dietary FA that is found in meat and dairy products derived from ruminant animals is conjugated linoleic acids (CLA). We have examined the effects of several CLA isomers on endothelial cell proliferation. 9t,11t‐CLA was the only isomer that inhibited bovine arotic endothelial cell (BAEC) [3H]methylthymidine incorporation (I50=35 μM), and this antiproliferative effect was time‐dependent. A small decrease (20%) in cell number was observed only at the highest concentration (60 μM) tested. The 9c,11t‐, 9c,11c‐, 10t 12c‐, and 11c,13t‐CLA isomers did not exhibit any antiproliferative effects over a 5–60 μM concentration range. α‐Tocopherol and BHT decreased BAEC proliferation, but pretreatment of cells with either of these antioxidants substantially attenuated the antiproliferative effect of 9t,11t‐CLA. No difference in lipid peroxidation, as measured by the thiobarbituric acid assay for malondialdehyde, was observed on treatment of endothelial cells with either 9t,11t‐ or 9c,11t‐CLA. However, a 43% increase in caspase‐3 activity was observed after incubating BAEC with 9t,11t‐CLA, suggesting that the antiproliferative effect of this isomer is partially due to an apoptotic pathway. In contrast to the above results with normal endothelial cells, these five CLA isomers all inhibited proliferation of the human leukemic cell line THP‐1, with the 9t,11t isomer again being the most (I50=60 μM) effective. These results confirm that different CLA isomers have different inhibitory potencies on the proliferation of normal and leukemic cells.
Parathyroid hormone stimulates phosphatidylethanolamine hydrolysis by phospholipase D in osteoblastic cells
Authors: Singh Amareshwar T. K. , Frohman Michael A. , Stern Paula H. 
Published: November 2006

AbstractParathyroid hormone (PTH) and phorbol‐12,13‐dibutyrate (PDBu) stimulate phospholipase D (PLD) activity and PC hydrolysis in UMR‐106 osteoblastic cells {Singh, A.T., Kunnel, J.G., Strieleman, P.J., and Stern, P.H. (1999) Parathyroid Hormone (PTH)‐(1–34), [Nle8, 18, Tyr34]PTH‐(3–34) Amide, PTH‐(1–31) Amide, and PTH‐Related Peptide‐(1–34) Stimulate Phosphatidylcholine Hydrolysis in UMR‐106 Osteoblastic Cells: Comparison with Effects of Phorbol 12,13‐Dibutyrate, Endocrinology 140, 131–137}. The current studies were designed to determine whether ethanolamine‐containing phospholipids, and specifically PE, could also be substrates. In cells labeled with 14C‐ethanolamine, PTH and PDBu treatment decreased 14C‐PE. In cells co‐labeled with 3H‐choline and 14C‐ethanolamine, PTH and PDBu treatment increased both 3H‐choline and 14C‐ethanolamine release from the cells. Choline and ethanolamine phospholipid hydrolysis was increased within 5 min, and responses were sustained for at least 60 min. Maximal effects were obtained with 10 nM PTH and 50 nM PDBu. Dominant negative PLD1 and PLD2 constructs inhibited the effects of PTH on the phospholipid hydrolysis. The results suggest that both PC and PE are substrates for phospholipase D in UMR‐106 osteoblastic cells and could therefore be sources of phospholipid hydrolysis products for downstream signaling in osteoblasts.
Effect of exercise on FA profiles in n−3 FA‐supplemented and‐nonsupplemented premenopausal women
Authors: Conquer Julie A. , Roelfsema Heather , Zecevic Julie , Graham Terry E. , Holub Bruce J. 
Published: November 2006

AbstractThe purpose of this double‐blind study was to investigate the influence of exercise on the FA profile of the nonesterified FA (NEFA) and phospholipid fractions in plasma of sedentary women supplemented with n−3 FA vs. women supplemented with oil containing no n−3 FA. Twenty sedentary, premenopausal women were randomly assigned to receive 12 capsules daily of either fish oil (3.5 g FPA and 2.4 g DHA per day, each as the ethyl ester) or evening primrose oil capsules (no detectable EPA or DHA). Each subject consumed the capsules for one menstrual cycle. At the end of the supplementation period, the sedentary subjects underwent an acute exercise trial [55% maximal oxygen consumption (VO2 max), 45 min] on a cycle ergometer. Two subjects in the fish oil group were removed from all calculations owing to noncompliance for reasons not related to side effects. There were no changes in the phospholipid composition of either group of women after exercise. In both control and fish oil‐supplemented women, NEFA levels in general rose after exercise. There were no changes in the percentage of any given individual NEFA in either supplementation group. However, absolute levels of certain individual NEFA (16∶0, 18∶0, 18∶1, and 18∶3n−3) increased with exercise. Women supplemented with fish oil had increased levels of n−3 NEFA [EPA, DHA, and docosapentaenoic acid (DPA)] prior to exercise. Exercise did not, however, increase the absolute levels of n−3 NEFA in the blood.
Ozonation of PC in ethanol: Separation and identification of a novel ethoxyhydroperoxide
Authors: Tagiri‐Endo Misako , Ono Kaori , Nakagawa Kiyotaka , Yotsu‐Yamashita Mari , Miyazawa Teruo 
Published: November 2006

AbstractThe product of the ozonolysis of 1‐palmitoyl‐2‐oleoyl‐sn‐glycero‐3‐phosphocholine in ethanol‐containing solvent was analyzed by chemiluminescence detection‐HPLC with on‐line electrospray MS, and characterized on the basis of NMR spectroscopy and MS in high‐resolution fast atom bombardment mode. The reaction yielded a large amount of a novel ethoxyhydroperoxide compound [1‐palmitoyl‐2‐(9‐ethoxy‐9‐hydroperoxynonanoyl)‐sn‐glycero‐3‐phosphocholine]. In addition to a structural analysis, we speculate on the reaction pathway and discuss the possibility of ethoxyhydroperoxide as a potentially reactive ozonized lipid in food and biological materials.
Triacylglycerol hydroperoxides not detected in pig small intestinal epithelial cells after a diet rich in oxidized triacylglycerols
Authors: Suomela Jukka‐Pekka , Ahotupa Markku , Kallio Heikki 
Published: November 2006

AbstractThe presence of TAG hydroperoxides in the epithelial cells of the small intestines in growing pigs was studied after they had consumed a diet rich in either nonoxidized or oxidized sunflower seed oil (PV in oils, 1 and 190 mequiv O2/kg, respectively). To obtain molecular‐level information on the oxidized TAG structures, a new approach based on TLC and HPLC‐electrospray ionization‐MS was used in the analysis of the samples. TAG hydroperoxides were not detected in the small intestinal mucosa or adipose tissue of either group, whereas TAG hydroxides, ketones, and epoxides were detected in all samples. The results suggest that dietary TAG hydroperoxides do not lead to the appearance of these molecules in the tissues.