bluuebunny/crossref_metadata_2025_split huggingface dataset:
Critical micelle concentrations of different classes of surfactants: A quantitative structure property relationship study
Authors: Anoune Naoual , Nouiri Moustapha , Berrah Yacine , Gauvrit Jean‐Yves , Lanteri Pierre 
Published: November 2006

AbstractThe critical micelle concentration (CMC) values of a 49‐surfactant dataset, among them 30 derived from α‐hydroxy acids or from gluconolactone synthesized and characterized in our laboratory, were subjected to Quantitative Structure Property Relationship (QSPR) studies. In this study, a principal component analysis (PCA) was used to compare the behavior of the synthesized surfactants to commercial ones that are used as detergents. The PCA shows the importance of the molecular structure of a surfactant in determining its activity (application field). We found that gluconolactone derivatives exhibited the same activity as those observed for glucopyranoside derivatives. A partial least squares regression was used to build a model that describes the CMC of diverse surfactants as a function of molecular descriptors.
Micellar association in simultaneous presence of organic salts/additives
Authors: Kumar Sanjeev , Khan Ziya Ahmad , Kabir‐ud‐Din  
Published: November 2006

AbstractViscosity measurements under Newtonian flow conditions had been performed on cetyltrimethylammonium bromide (CTAB) aqueous solutions in the combined presence of sodium salts of aromatic acids (sodium salicylate, NaSal; sodium benzoate, NaBen; sodium anthranilate, NaAn) and organic additives (1‐hexanol, C6OH; n‐hexylamine, C6NH2) at 30°C. On addition of C6OH or C6NH2, the viscosity of 25 mM CTAB solution remained nearly constant without salt as well as with a lower salt concentration. This is due to low CTAB concentration which is not sufficient to produce structural changes in this concentration range of salts. However, as the salt concentration was increased further, the effect of C6OH/C6NH2 addition was different with different salts: The viscosity first increased; then a decrease was observed with the former while with C6NH2 a decrease followed by constancy appeared in plots of relative viscosities (ηr) vs. organic additive concentrations. At further higher salt concentration, the magnitude of ηr was much higher. The viscosity increase is explained in terms of micellar growth and the decrease in terms of swollen micelle formation (due to interior solubilization of organic additive) or micellar disintegration (due to formation of water + additive pseudophase).
Effect of nutrients on optimal production of biosurfactants by Pseudomonas putida—A gujarat oil field isolate
Authors: Pruthi V. , Cameotra S. S. 
Published: November 2006

AbstractNutritional requirements for maximal production of biosurfactant by an oil field bacterium Pseudomonas putida were determined. The optimal concentrations of nitrogen, phosphate, sulfur, magnesium, iron, potassium, sodium, calcium, and trace elements for maximal production of biosurfactants were ascertained, and a new “Pruthi and Cameotra” salt medium was formulated. Data show that maximal biomass (2.4 g L−1) and biosurfactant production (6.28 g L−1) takes place after 72 h of growth on 2% hexadecane. The biosurfactant was produced optimally over pH and temperature ranges of 6.4–7.2 and 30–40°C, respectively. That the highest biosurfactant yield was obtained during late log phase of growth indicates that the biosurfactant is a secondary metabolite.
Additive‐induced association in unconventional systems: A case of the hydrotrope
Authors: Kumar Sanjeev , Parveen Nahid , Kabir‐ud‐Din  
Published: November 2006

AbstractIt is well known that hydrotropes have a very high minimum hydrotrope concentration (MHC), posing a question on their applications. We have found that MHC (obtained by conductivity and surface tension measurements) can be reduced by the addition of foreign materials. The association tendency can be improved by the addition of salts, n‐alkanols, and ureas. Urea decreases or increases the MHC depending on whether the urea content is lower or higher (e.g., the increased solubility of sparingly soluble riboflavin corroborates the increase in the hydrotropic properties of the system). In the present work, the association tendencies of sodium salicylate (a well‐known hydrotrope), sodium dodecyl sulfate, and sodium bromide were compared. The results have direct implications in the mechanism of protein denaturation and may provide insight into the role of urea in supramolecular assemblies.
Contact angle of surfactant solutions on precipitated surfactant surfaces. III. Effects of subsaturated anionic and nonionic surfactants and NaCl
Authors: Luepakdeesakoon Bungon , Saiwan Chintana , Scamehorn John F. 
Published: November 2006

AbstractThe contact angles of saturated calcium dodecanoate (CaC12) solutions containing a second subsaturated surfactant on a precipitated CaC12 surface were measured by using the drop shape analysis technique. The subsaturated surfactants used were anionic sodium dodecylsulfate (NaDS), anionic sodium octanoate (NaC8), and nonionic nonylphenol polyethoxylate (NPE). Comparing at the critical micelle concentration (CMC) for each surfactant, NaC8 was the best wetting agent, followed by NaDS, with NPE as the poorest wetter (contact angles of 320, 420, and 620, respectively). Surface tension at the CMC increased in the order NaC8<NPE<NaDS, and subsaturated surfactant adsorption increased in the order NPE≪NaDS (1.4 vs. 84 μmole/g); adsorption of the NaC8 was not measurable. Interfacial tension (IFT) reduction at the solid‐liquid interface due to subsaturated surfactant adsorption is an important contribution to contact angle reduction, in addition to surface tension reduction at the air‐water interface. Surfactant adsorption onto the soap scum solid is crucial to solid‐liquid IFT reduction and to good wetting. The fatty acid was the best wetting agent of the three surfactants studied, probably because calcium bridging with the carboxylate group synergizes surfactant adsorption onto the solid of the higher molecular weight soap. NaCl added to NaDS surfactant results in depressed CMC, lower surface tension at the CMC, decreased NaDS adsorption onto the solid, and decreased reduction in solid‐liquid IFT. The contact angle is not dependent on the NaCl concentration for NaDS. The NaCl causes an increased tendency to form monolayers, which decrease air‐water surface tension, but a decreased tendency to form adsorbed aggregates on the solid; the two trends offset each other, so wettability is not affected by added salt. The Zisman equation does not describe the wetting data for these systems well except for NaDS, further emphasizing the danger of ignoring solid‐liquid IFT reduction in interpreting wetting data in these systems.
Enhanced triolein removal using microemulsions formulated with mixed surfactants
Authors: Tongcumpou C. , Acosta E. J. , Scamehorn J. F. , Sabatini D. A. , Yanumet N. , Chavadej S. 
Published: November 2006

AbstractIn previous work, a microemulsion‐based formulation approach yielded excellent laundry detergency with hydrophobic oily soils hexadecane and motor oil. In this work, the same approach is used in detergency of triolein, which is a model triglyceride, some of the most difficult oils to be removed from fabric. The linker concept was applied in formulation of the microemulsion system. Three different surfactants were used: (i) dihexyl sulfosuccinate, an ionic surfactant with a moderate hydrophile‐lipophile balance (HLB); (ii) secondary alcohol ethoxylate, a lipophilic nonionic surfactant with a very low HLB; and (iii) alkyl diphenyl oxide disulfonate (ADPODS), a hydrophilic anionic surfactant with a very high HLB. The phase behavior and interfacial tension (IFT) of the surfactant systems were determined with different concentrations of ADPODS. The results indicate that as the HLB of the system increases, a higher salinity is required to shift the phase transition from Winsor Type I to Type III to Type II. The three formulations at different salinities were used in detergency experiments to remove triolein from polyester/cotton sample fabric. The results showed that there were two peaks of maximum detergency in the range of salinity from 0.1% to 10% NaCl. The higher the hydrophilicity of the system, the higher the salinity required for maximum detergency. The results of the dynamic IFT and the detergency performance from two rinsing methods lead to the hypothesis that one of these maxima in detergency results from a spreading or wetting effect. The other maximum in detergency is believed to be related to ultralow IFT associated with oil/water middle‐phase microemulsion formation. Triolein removal exceeding 80% was attained, validating the microemulsion approach to detergency.
Preventing discoloration of squalene‐soiled cotton fabrics with antioxidants
Authors: Chi Yong‐Seung , Obendorf S. Kay 
Published: November 2006

AbstractRemoval of discoloration caused by aged oily soils is difficult because oily soils undergo autoxidation, which results in polymerization and formation of chromophores. Use of antioxidants and a reducing agent was investigated for their impact on appearance retention and soil removal. The effect of a reducing agent, sodium dithionite, on the removal of aged squalene from cotton fabrics was studied as a pretreatment to laundering, which enhanced the removal of squalene as well as whiteness restoration. Increases in treatment concentration and time increased color removal. However, no significant increase was found in oil removal, suggesting that the role of the reducing agent is mainly a reductive bleaching action. Thus, the color will probably reverse by oxidation over time making this approach a not‐so‐promising laundry treatment. As a method of preventing discoloration of oily soiled textile materials, antioxidants Irganox® 1010, t‐butylhydroxyanisole and α‐tocopherol were examined; they were found to be effective antioxidants for this purpose by preventing the discoloration of squalene upon aging. With Irganox® 1010, this prevention occurred without decreasing the detergency of the oil. Most importantly, these antioxidants either did not stain the substrate or showed very low levels of staining upon usage. The biggest barrier to applying antioxidants on textiles is their hydrophobic nature. A search for water‐soluble antioxidants with nonstaining and good oxidation inhibiting properties is necessary.
Characteristic properties of cutting fluid additives derived from the reaction products of hydroxyl fatty acids with some acid anhydrides
Authors: Tomoda Hideyuki , Sugimoto Yasuhiro , Tani Yumiko , Watanabe Shoji 
Published: November 2006

AbstractSeveral adducts were prepared from the thermal reaction of hydroxyl fatty acids (ricinoleic acid oligomers, 12‐hydroxystearic acid oligomers, oleyl alcohol, dehydrated castor oil fatty acids, and dimer acid) with maleic anhydride and screened as water‐soluble cutting fluids. For example, aqueous solutions of triethanolamine salts with the products of ricinoleic acid oligomers, 12‐hydroxystearic acid dimer, and 12‐hydroxysteric acid hexamer showed good antirust properties for waterbased cutting fluids. Various half esters of hydroxyl fatty compounds with acid anhydrides were prepared. Aqueous solutions of triethanolamine salts of half esters of maleic anhydride and succinic anhydride and phthalic anhydride with hydroxyl fatty acids gave good antirust and antiwear properties for waterbased cutting fluids.
Characterization of simple and reproducible vascular stenosis model in hypercholesterolemic hamsters
Authors: Matsuno Hiroyuki , Kozawa Osamu , Niwa Masayuki , Abe Akira , Takiguchi Yoshiharu , Uematsu Toshihiko 
Published: November 2006

AbstractThe importance of low‐density lipoprotein (LDL) in the etiology of atherosclerosis is well recognized. We have established a reproducible stenosis model in hypercholesterolemic hamsters, and the process of arterial stenosis by thrombus or neointima was studied and compared with that in normal hamsters. The level of plasma LDL was 4.6 times higher in hamsters fed a high‐cholesterol diet than in hamsters fed normal food. Endothelial injury in right common carotid arteries was induced using a modified catheter. Arterial blood flow was monitored continuously using a Doppler flow probe. Arterial patency after the initiation of injury in high‐cholesterol hamsters was significantly changed as compared with that of normal hamsters. Neointima was observed 2 wk after the vascular injury. The neointimal area of high‐cholesterol hamsters was significantly larger than that of normal hamsters. To characterize the stenosis in hypercholesterolemic hamsters, we measured platelet aggregation, thrombin time, activated partial thromboplastin time, and proliferating smooth muscle cells (SMC) in vitro and in vivo. The half‐maximal inhibitory concentration value for platelet aggregation induced by thrombin or collagen, the DNA synthesis stimulated by plateletderived growth factor (PDGF)‐BB, and 5‐bromo‐2‐deoxy‐uridine labeling indices (proliferating index of SMC in vivo) in high‐cholesterol hamsters were each significantly higher than the comparable value from normal hamsters. However, specific binding of PDGF‐BB in SMC was not different between the two types of hamsters. Furthermore, we investigated the inhibitory effects of probucol or losartan on neointima formation using this model. Probucol, but not losartan, significantly reduced the neointimal area in hypercholesterolemic hamsters. These findings indicated that high levels of plasma LDL strongly contributed to the development of thrombus and neointima formation via both up‐regulation of platelet aggregation and the enhancement of SMC proliferation. This stenosis model may be useful for the investigation of hypercholesterolemia‐associated cardiovascular diseases.
A novel sphingophosphonolipid head group 1‐hydroxy‐2‐aminoethyl phosphonate in Bdellovibrio stolpii
Authors: Watanabe Yoko , Nakajima Masaharu , Hoshino Tsutomu , Jayasimhulu Koda , Brooks Elwood E. , Kaneshiro Edna S. 
Published: November 2006

AbstractMembers of the bacterial genus Bdellovibrio include strains that are free‐living whereas others are known to invade and parasitize larger Gram‐negative bacteria. The bacterium can synthesize several sphingophospholipid compounds including those with phosphoryl bonds as well as phosphonyl bonds. In the present study, the dominant sphingophosphonolipid component was isolated by column chromatography, and the long‐chain bases, fatty acids, and polar head groups were identified by thin‐layer and gas‐liquid chromatographic procedures. The definitive structural identity of the sphingolipid was established by nuclear magnetic resonance and mass spectrometry of hydrolysis products and the intact compound. The compound was identified as N‐2′‐hydroxypentadecanoyl‐2‐amino‐3,4‐dihydroxyheptadecan‐1‐phosphono‐(1‐hydroxy‐2‐aminoethane).
Interaction of CETP inhibitory peptide and lipoprotein substrates in cholesteryl ester transfer assay: Relationship between association properties and inhibitory activities
Authors: Cho Kyung‐Hyun , Lee Ju‐Young , Choi Myung‐Sook , Bok Song‐Hae , Park Yong Bok 
Published: November 2006

AbstractIn a previous study, CETP inhibitory peptide (3 kDa) was isolated from hog plasma. The peptide, synthesized chemically according to the amino acid sequence of the 3‐kDa peptide (designated P28), showed CETP inhibitory activity both in vitro and in vivo [Cho et al. (1998) Biochim. Biophys. Acta 1391, 133–144]. We report herein further unique features of P28 when it was associated with the cholesteryl ester (CE)‐donor and‐acceptor lipoproteins. Lipoprotein substrates with P28 present in both HDL (as a CE‐donor) and LDL (as a CE‐acceptor) served as poor substrates, with CE‐transfer activity decreased up to 60% compared to normal substrates without P28. P28 was found to be located in HDL fractions of hog plasma and showed the same electromobility as that visualized by PAGE on 7% polyacrylamide gel under nondenaturing conditions. Addition of apolipoprotein A‐1 (apoA‐1) or apoB antibody to a normal CE‐transfer mixture did not alter CE‐transfer activity. However, addition of apoA‐1 or −B antibody to a CETP‐inhibition mixture decreased the inhibitory activity of P28 by ca. 20%. Western blot analysis revealed that P28 was associated only with human and hog HDL among several lipoproteins purified from human, hog, and rabbit. CFTP‐inhibition assays with various lipoprotein substrates revealed that P28 exhibited substrate‐specific inhibitory activity. The inhibitory activity of P28 was highly dependent on the type of lipoprotein substrate (whether CE‐donor or‐acceptor); P28 inhibited CE transfer from HDL to LDL, but it did not inhibit CE transfer from HDL to HDL.
Correlation between fatty acyl composition in neutral and polar lipids and enzyme activities from various tissues of calcium‐deficient rats
Authors: Marra Carlos A. , Rimoldi Omar , de Alaniz María J. T. 
Published: November 2006

AbstractIn this study we investigated the changes induced by feeding rats a calcium‐deficient diet (0.5 g Ca/kg diet) during 65 d after weaning. Phospholipase A2, acyl‐Co synthetase and FA Δ9‐, Δ6‐, and Δ5‐desaturase activities were also determined. Calcium deficiency evoked a general alteration in the quality and proportion of the FA chains acylated to neutral and polar lipids from liver, lungs, spleen, brain, kidneys, fat, articular cartilage, erythrocyte ghosts, and plasmas, characterized by an increment of saturated FA and a significant depletion of polyunsaturated acids derived from linoleate and α‐linolenate. Several interlipid and lipid/protein relationships were also modified in microsomes from calcium‐deprived rats, with a concomitant reduction in the rotational mobility of the probe diphenylhexatriene. Phospholipase A2 and acyl‐CoA synthetase activities were also decreased and increased, respectively, in some tissues from calcium‐deficient rats, whereas Δ9‐, Δ6‐ and Δ5‐desaturases were significantly depressed. We conclude that changes in tissue fatty acyl composition evoked by calcium deprivation are due to alterations in the acylation/deacylation cycles via inhibition of the phospholipase A2. These changes were reflected in the physicochemical properties of the membranes, which in turn inhibits desaturase activities. A possible failure in the transcriptional rate for desaturase‐mRNA was also discussed.
Endothelial vasodilatory function is predicted by circulating apolipoprotein B and HDL in healthy humans
Authors: Steer Peter , Hulthe Johannes , Millgård Jonas , Sarabi Dennis M. , Basu Samar , Vessby Bengt , Lind Lars 
Published: November 2006

AbstractEndothelium‐dependent vasodilation (EDV), LDL particle size, and antibodies against oxidized LDL (oxLDLab) have been shown to be related to the development of atherosclerosis and cardiovascular disease. In this study, we investigated whether LDL particle size, oxLDLab, apolipoproteins, and lipoproteins are related to endothelial vasodilatory function in a population sample of 58 apparently healthy subjects aged 20 to 69 yr. EDV and endothelium‐independent vasodilation (EIDV) were studied in the forearm during local administration of methacholine chloride (2 and 4 μg/min) or sodium nitroprusside (5 and 10 μg/min). Forearm blood flow was determined with venous occlusion plethysmography. In multiple stepwise regression analyses, neither oxLDLab nor small LDL particles were significantly predictive of endothelial vasodilatory function. Instead, a high level of apolipoprotein B (apoB) was an independent predictor of both attenuated EDV and EIDV (r=−0.43, P<0.01, and r=−0.34, P<0.05, respectively). HDL cholesterol, on the other hand, was the only lipid variable that was significantly related to the EDV to EIDV ratio, an index of endothelial vasodilatory function (r=0.35, P<0.01). The inverse associations between apoB and both EDV and EIDV indicate that apoB might be an early marker of structural vascular changes in healthy subjects, whereas HDL seems to be more specifically related to endothelial vasodilatory function.
The role of cytochrome P450 in the regulation of cholesterol biosynthesis
Authors: Gibbons Geoffrey F. 
Published: November 2006

AbstractA ubiquitously expressed member of the cytochrome P450 superfamily, CYP51, encodes lanosterol 14α‐demethylase, the first step in the conversion of lanosterol into cholesterol in mammals. The biosynthetic intermediates of lanosterol 14α‐demethylation are oxysterols, which inhibit HMG‐CoA reductase and sterol synthesis in mammalian cells in vitro. These oxysterols (5α‐lanos‐8‐en‐3β,32‐diol and 3β‐hydroxy‐5α‐lanost‐8‐en‐32‐al) are efficiently converted into cholesterol in vitro and are generally considered to be natural cholesterol precursors. When added to hepatocytes in high concentrations, besides their conversion into cholesterol, they are also rapidly metabolized into more polar sterols and into steryl esters. The 15α‐ and 15β‐hydroxy epimers of 5α‐lanost‐8‐en‐3β‐ol are also rapidly metabolized into more polar sterols and steryl esters but are not converted efficiently into cholesterol. Polar sterol formation from all these oxysterols is dependent on an active form of cytochrome P450. Oxysterols are potent regulators of the activities of transcription factors of the sterol regulatory element‐binding protein family and of liver X‐receptor α. It is proposed that the rapid, cytochrome P450‐dependent metabolism of naturally occurring regulatory oxysterols provides a route for their deactivation so that they become incapable of affecting gene transcription. Inhibition of cytochrome P450 by the drug ketoconazole prevents the inactivation of such oxysterols, leading to a prolonged suppression of hepatic HMG‐CoA reductase in vivo and in vitro.
Studies toward the synthesis of the shark repellent pavoninin‐5
Authors: Williams John R. , Chai Deping , Gong Hua , Zhao Wei , Wright Dominic 
Published: November 2006

AbstractSharks are the most dangerous predators of people in the sea, resulting in people being mauled and killed each year. A shark repellent could help to diminish this danger. The aglycone of the shark repellent pavoninin‐5, (25R)‐cholest‐5‐en‐3β,15α,26‐triol (5a), was synthesized from diosgenin (9). Removing mercury from the Clemmensen reduction of 9 gave a higher yield of (25R)‐cholest‐5‐en‐3β,16β,26‐triol, 10a, and was also more environmentally friendly. Attempted methods for the transposition of the C‐16β hydroxyl to the 15α position are described. A successful method for this transposition via the 15α‐hydroxy‐16‐ketone, 8a, using the Barton deoxygenation reaction on the 16‐alcohol 14b, is reported.
Microtubular integrity differentially modifies the saturated and unsaturated fatty acid metabolism in cultured hep G2 human hepatoma cells
Authors: Marra Carlos A. , de Alaniz María J. T. 
Published: November 2006

AbstractThe influence of cytoskeleton integrity on the metabolism of saturated and unsaturated FA was studied in surface cultures and cell suspensions of human Hep G2 hepatoma cells. We found that colchicine (COL), nocodazol, and vinblastin produced a significant inhibition in the incorporation of labeled saturated FA, whereas incorporation of the unsaturated FA remained unaltered. These microtubule‐disrupting drugs also diminished Δ9‐, Δ5‐, and Δ6‐desaturase capacities. The effects produced by COL were dose (0–50 μM) and time (0–300 min) dependent, and were antagonized by stabilizing agents (phalloidin and DMSO). Dihydrocytochalasin B (20μM) was tested as a microfilament‐disrupting drug and produced no changes in either the incorporation of [14C]FA or the desaturase conversion of the substrates. We hypothesized that the interactions between cytoskeleton and membrane proteins such as FA desaturases may explain the functional organization, facilitating both substrate channeling and regulation of unsaturated FA biosynthesis.