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Oleic Acid (oleic + acid)
Terms modified by Oleic Acid Selected AbstractsACCUMULATION OF OLEIC ACID IN HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE) UNDER NITROGEN STARVATION OR HIGH LIGHT IS CORRELATED WITH THAT OF ASTAXANTHIN ESTERS1JOURNAL OF PHYCOLOGY, Issue 2 2002Mirash Zhekisheva The chlorophyte Haematococcus pluvialis accumulates large quantities of astaxanthin under stress conditions. Under either nitrogen starvation or high light, the production of each picogram of astaxanthin was accompanied by that of 5 or 3,4 pg of fatty acids, respectively. In both cases, the newly formed fatty acids, consisting mostly of oleic (up to 34% of fatty acids in comparison with 13% in the control), palmitic, and linoleic acids, were deposited mostly in triacylglycerols. Furthermore, the enhanced accumulation of oleic acid was linearily correlated with that of astaxanthin. Astaxanthin, which is mostly monoesterified, is deposited in globules made of triacylglycerols. We suggest that the production of oleic acid-rich triacylglycerols on the one hand and the esterification of astaxanthin on the other hand enable the oil globules to maintain the high content of astaxanthin esters. [source] Preparation of Nanometer-Sized ,-Alumina Powders by Calcining an Emulsion of Boehmite and Oleic AcidJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2002Chih-Peng Lin This study proposes a method to form ultrafine ,-Al2O3 powders. Oleic acid is mixed with Al(OH)3 gel. The gel is the precursor of the Al2O3. After it is mixed and aged, the mixture is calcined in a depleted oxygen atmosphere between 25° and 1100°C. Oleic acid evaporates and decomposes into carbon during the thermal process. Residual carbon prevents the growth of agglomerates during the formation of ,-Al2O3. The phase transformation in this process is as follows: emulsion ,,-Al2O3,,-Al2O3,,-Al2O3,,-Al2O3. This process has no clear , phase. Aging the mixed sample lowers the formation temperature of ,-Al2O3 from 1100° to 1000°C. The average crystallite diameter is 60 nm, measured using Scherrer's equation, which is consistent with TEM observations. [source] Novel approach to improve permeation of ondansetron across shed snake skin as a model membraneJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 6 2001Koichi Takahashi The purpose of this study was to investigate the feasibility of transdermal drug delivery of ondansetron, an antagonist of the 5-HT3 receptor, used for the treatment of chemotherapy-induced emesis. The permeability of ondansetron from an aqueous suspension through shed snake skin as a model membrane was very low and in order to improve it, several enhancers were tested. Ethanol increased the flux at a concentration of 40% or more. The solubility of ondansetron also increased as the ethanol concentration increased. The permeability coefficient increased after pretreatment of the shed snake skin with Azone, oleic acid or lauryl alcohol. Further improvement of the permeability was observed when ethanol was combined with other enhancers and was maximum for the combination of ethanol and oleic acid. Oleic acid dramatically increased the partition of ondansetron to n -hexane and shed snake skin. Oleic acid may enhance the permeation of ondansetron in two ways: by a direct effect on the stratum corneum or via counterion formation of an ion-pair. The maximum flux obtained from the combination of ethanol and other enhancers seems to be high enough to obtain a therapeutic effect. [source] Preparation of Nanometer-Sized ,-Alumina Powders by Calcining an Emulsion of Boehmite and Oleic AcidJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 1 2002Chih-Peng Lin This study proposes a method to form ultrafine ,-Al2O3 powders. Oleic acid is mixed with Al(OH)3 gel. The gel is the precursor of the Al2O3. After it is mixed and aged, the mixture is calcined in a depleted oxygen atmosphere between 25° and 1100°C. Oleic acid evaporates and decomposes into carbon during the thermal process. Residual carbon prevents the growth of agglomerates during the formation of ,-Al2O3. The phase transformation in this process is as follows: emulsion ,,-Al2O3,,-Al2O3,,-Al2O3,,-Al2O3. This process has no clear , phase. Aging the mixed sample lowers the formation temperature of ,-Al2O3 from 1100° to 1000°C. The average crystallite diameter is 60 nm, measured using Scherrer's equation, which is consistent with TEM observations. [source] Adiposity, fatty acid composition, and delta-9 desaturase activity during growth in beef cattleANIMAL SCIENCE JOURNAL, Issue 5 2006Stephen B. SMITH ABSTRACT Oleic acid (18:1n-9) is the most abundant fatty acid in bovine adipose tissue. Because most of the lipid in bovine muscle is contributed by intramuscular adipocytes, oleic acid also is the predominant fatty acid in beef. In many species, the concentration of oleic acid in adipose tissue is dictated by the average concentration of oleic acid in the diet, but in ruminant species such as beef cattle, oleic acid is hydrogenated largely to stearic acid by ruminal microorganisms. In these species, the concentration of oleic acid in adipose tissue is dependent upon the activity of ,9 desaturase, encoded by the stearoyl coenzyme A desaturase (SCD) gene. Expression of the SCD gene is essential for bovine preadipocyte differentiation, and desaturase gene expression and catalytic activity increase dramatically as adipose tissue mass increases after weaning. Feeding a hay-based diet to American Wagyu steers to a typical Japanese bodyweight endpoint (650 kg) markedly stimulated desaturase enzyme activity as well as the accumulation of both oleic acid and intramuscular lipid, but the increase in oleic acid and intramuscular lipid was much less in hay-fed Angus steers. Increasing the concentration of oleic acid improves the palatability and healthiness of beef, and Korean Hanwoo and Japanese Black (and American Wagyu) seem especially well adapted to accumulate oleic acid in their adipose tissue. [source] Effects of exogenous fatty acids and cholesterol on aminopeptidase activities in rat astrogliaCELL BIOCHEMISTRY AND FUNCTION, Issue 4 2002M. J. Ramķrez-Expósito Abstract Several studies have addressed the interaction between fatty acids and lipids with central nervous system peptides. Because aminopeptidases (AP) are involved in the regulation of neuropeptides, this work studies several AP expressed in cultured astroglia, after exogenous addition of oleic and linoleic fatty acids and cholesterol to the culture medium. Alanyl-AP, arginyl-AP, cystyl-AP, leucyl-AP, tyrosyl-AP and pyroglutamyl-AP activities were analysed in whole cells using the corresponding aminoacyl-,-naphthylamides as substrates. Oleic acid inhibits alanyl-AP, cystyl-AP and leucyl-AP activities, whereas linoleic acid inhibits alanyl-AP, arginyl-AP and tyrosyl-AP activities. Neither oleic acid nor linoleic acid modifies pyroglutamyl-AP activity. In contrast, cholesterol increases arginyl-AP, cystyl-AP, leucyl-AP, tyrosyl-AP and pyroglutamyl-AP activities, although it does not modify alanyl-AP activity. The changes reported here suggest that oleic and linoleic fatty acids and cholesterol can modulate peptide activities via their degradation route involving aminopeptidases; each of them being differentially regulated. Copyright © 2002 John Wiley & Sons, Ltd. [source] Natural vegetable fats in the prevention of irritant contact dermatitisCONTACT DERMATITIS, Issue 1 2002S. Schliemann-Willers Chronic irritant contact dermatitis (ICD) is one of the most pressing problems in occupational medicine and is common in the food processing industry. To date, protective creams that fulfil the special requirements in the foodstuffs industry have not been available. Therefore, we studied the efficacy of pre-exposure application of natural vegetable fats in the prevention of experimentally induced ICD. A panel of 20 healthy volunteers was tested with a repetitive irritation test using sodium lauryl sulfate (SLS) as a standard irritant in a randomized study. Application sites were assessed clinically and by the use of bioengineering techniques (evaporimetry, chromametry, and corneometry). Rape seed and palm fats showed significant protective potential. Gas-chromatographic analysis revealed differences in the fatty acid composition of the vegetable. Higher content of linoleic acid and lower content of oleic acid was associated with beneficial effects. Our results are a new approach in the prevention of ICD and towards the development of new protective preparations for workplaces in the foodstuffs industry. [source] Effects of metformin and oleic acid on adipocyte expression of resistinDIABETES OBESITY & METABOLISM, Issue 1 2006R Rea Aim:, The adipocyte-secreted hormone resistin has been implicated in obesity-induced insulin resistance and type 2 diabetes, but pharmacological and dietary factors that regulate resistin gene expression and the effects of resistin on cellular glucose uptake in muscle have not been clearly defined. Methods:, Expression of resistin mRNA was studied in differentiated 3T3-L1 adipocytes by using real-time semiquantitative reverse transcription-polymerase chain reaction. The effects of resistin on insulin-stimulated and insulin-independent 2-deoxyglucose uptake were evaluated in L6 muscle cells. Results:, Insulin 1 µm and rosiglitazone 10 µm markedly reduced resistin mRNA expression (relative to the control gene TF2D) by 4.7-fold (p < 0.05) and 5.3-fold (p < 0.02), respectively. Similar reductions in resistin mRNA were demonstrated with metformin 100 µm (6.2-fold reduction, p < 0.02) and oleic acid 100 µm (3.9-fold reduction, p < 0.03). Resistin 1 µm significantly reduced maximum insulin-stimulated 2-deoxyglucose uptake in L6 cells from 634 to 383% (relative to 100% for control, p < 0.001), and co-administration of rosiglitazone had no effect on resistin-induced insulin resistance. In the absence of insulin, however, resistin increased glucose uptake dose-dependently (e.g., 1.75-fold at 5 µm, p < 0.001) via a mitogen-activated protein kinase-dependent pathway. Conclusions:, These results demonstrate that various glucose-lowering therapies and oleic acid reduce resistin gene expression in isolated adipocytes, and that resistin impairs insulin-stimulated glucose uptake in skeletal muscle-derived cells. [source] Acute toxicity of fatty acids to the freshwater green alga Selenastrum capricornutumENVIRONMENTAL TOXICOLOGY, Issue 5 2003Yasushi Kamaya Abstract The acute toxicity of fatty acids (C14 to C18) commonly found in wood was determined by the standard algal growth inhibition test using the freshwater green alga Selenastrum capricornutum. Toxicity, quantified as IC50 values, varied depending on the number of total carbons and double bonds. Of the tested acids, oleic (cis -9-octadecenoic) acid showed the highest toxicity (72-h IC50 = 0.47 mg/L) to the alga, and triolein, a triglyceride of oleic acid, showed no apparent toxicity. Further examination of a series of C18:1 acids with a double bond at the 6, 11, or 12 position revealed that both double-bond position and cis or trans configuration affected toxicity. The 72-h IC50 data for these fatty acids and related compounds seemed to correlate well with the melting point (mp), showing two separate linear relationships: at mp < 35°C toxicity increased with increasing melting point, and at mp > 40°C toxicity decreased with melting point. © 2003 Wiley Periodicals, Inc. Environ Toxicol 18: 289,294, 2003. [source] Fatty acid incorporation in endothelial cells and effects on endothelial nitric oxide synthaseEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 9 2007S. Couloubaly Abstract Background The nature of fatty acids provided by the diet as well as plasma lipid metabolism can modify the composition and properties of plasma membrane and thus the activity of membrane proteins. In humans, as well as in experimental models, diabetes is associated with both an alteration in serum lipid profile and a documented endothelial dysfunction. This in vitro study investigated on an immortalized human endothelial cell line (EA.hy 926) the specific effects of several free fatty acids (FFAs) on the composition of cellular membranes and the regulation of endothelial nitric oxide synthase (eNOS). Materials and methods 0·1% of lipid deprived serum was added to the incubation medium with 25 mm glucose in order to study the effects of individual fatty acids: myristic acid, palmitic acid, stearic acid, oleic acid or linoleic acid at 100 µm bound with albumin. The effects of the FFAs on the endothelial nitric oxide synthase were investigated on mRNA level by quantitative PCR, on protein level and Ser1177 phosphorylation by Western blot and on enzymatic activity on living cells using radiolabelled arginine. Results Free linoleic acid increased the membrane content in n-6 fatty acids (mainly C18: n-6 and its metabolites) with a decrease in saturated and monounsaturated fatty acids. These conditions decreased the basal eNOS activity and reduced the phosphorylation of eNOS-Ser1177 due to activation by histamine. Free palmitic acid enriched the membranes with 16 : 0 with a slight decrease in monounsaturated fatty acids. These conditions increased eNOS activation without increasing Ser1177 phosphorylation upon histamine activation. The addition of the other FFAs also resulted in modifications of membrane composition, which did not to affect eNOS-Ser1177 phosphorylation. Conclusion Among the fatty acids used, only modification of the membrane composition due to linoleic acid supply disturbed the basal enzymatic activity and Ser1177 phosphorylation of eNOS in a way that limited the role of histamine activation. Linoleic acid might involve the dysfunction of both eNOS basal activity and its phosphorylation status and may then contribute to an impaired vasodilatation in vivo. [source] The Oriented Self-Assembly of Magnetic Fe3O4 Nanoparticles into Monodisperse Microspheres and Their Use as Substrates in the Formation of Fe3O4 NanorodsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2008Guangcheng Xi Abstract We describe a facile solvothermal route for the large-scale preparation of ferromagnetic Fe3O4 sub-micrometer spheres and nanorods by using FeCl3 as the iron source, oleic acid as the surfactant, and ethylene glycol as the reducing agent and solvent. The as-synthesized Fe3O4 microspheres are composed of a mess of Fe3O4 nanoparticles with a size of 10 nm and have nearly monodisperse diameters that can be controlled in the range 100,410 nm. HRTEM images and SAED patterns show that these microspheres present a "single-crystalline" nature, which can be attributed to the highly oriented assembly of the small Fe3O4 nanoparticles. Interestingly, by using the pre-synthesized Fe3O4 microspheres as the growth substrate, single-crystalline Fe3O4 nanorods can be formed on the surfaces of the microspheres. These nanorods are about 7,20 nm in diameter and 120,400 nm in length, and have smooth surfaces. The formation mechanisms of the Fe3O4 microspheres and nanorods have been investigated and discussed. Furthermore, the magnetic properties of the as-synthesized microspheres and nanorods have also been investigated and the magnetization saturation values are 74.6 and 92.3 emu/g, respectively.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Commercial Runner peanut cultivars in the USA: Fatty acid compositionEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 2 2010Eui-Cheol Shin Abstract Though peanuts are classified as a high-fat food, they possess good proportions of fatty acids deemed as heart healthy. The fatty acid compositions of Runner peanuts were determined for commercially grown cultivars over two recent crop years. GC-FID analyses revealed that the fatty acid levels for Runner peanuts were significantly (p,<0.05) different among the normal, mid-, and high-oleic peanuts investigated. Oleic acid-to-linoleic acid (O/L) ratios were found to be 1.93,±,0.30, 5.25,±,1.12, and 16.9,±,5.20 for normal, mid-, and high-oleic peanut lipids, respectively. Tamrun OL01 possessed a fatty acid profile characteristic of a mid-oleic cultivar. From the sample set (n,=,151), mean %,weights for oleic acid and linoleic acid were 52.09,±,2.84 and 27.38,±,2.60 in normal, 69.33,±,3.18 and 13.66,±,2.35 in mid-oleic, and 78.45,±,2.05 and 5.11,±,1.67 in high-oleic peanuts, respectively. Cluster analysis segregated cultivars based on fatty acids into normal, mid-, and high-oleic groups. Factorial analysis revealed that cultivar effects were significant (p,<0.01) for all fatty acids, except for lignoceric acid. Cultivar effects were also highly significant (p,<0.001) for O/L, IV, unsaturated/saturated fatty acid (U/S) ratio, and %,saturation. Significant crop year effects were shown for palmitic, oleic, arachidic, gondoic, and lignoceric acids, as well as U/S ratio and %,saturation. Healthy unsaturated fats accounted for ,80% in all crop years and cultivars. [source] Catalytic cleavage of methyl oleate or oleic acidEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 1 2010Angela Köckritz Abstract Different reaction pathways are discussed for the Os-catalyzed oxidation of methyl oleate and oleic acid using O2/aldehyde as oxidation system. Monomethyl azelate and pelargonic acid were the main products obtained in yields of approximately 50,70% starting from methyl oleate. Besides, varying amounts of methyl 9,10-epoxystearate and methyl 9,10-dihydroxystearate were found as by-products. Azelaic acid and pelargonic acid were obtained exclusively from oleic acid used as reactant. Some mechanistic considerations led to the conclusion that the observed products are formed in parallel reaction paths. The effective oxidant for the scission of the C=C double bond seems to be very likely an in situ formed peracid generated by Os-catalysis from O2/aldehyde. Additional investigations concerning the cleavage of oleic acid and methyl oleate with in situ formed performic acid from H2O2/formic acid corroborate this assumption. [source] Chemical evaluation of some paprika (Capsicum annuum L.) seed oilsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 12 2009Bertrand Matthäus Dr. Abstract The oil contents of seeds from paprika (Capsicum annuum L.) collected from different locations in Turkey and Italy varied in a relatively wide range from 8.5,g/100,g to 32.6,g/100,g. The fatty acid, tocopherol and sterol contents of the oils from different paprika seeds were investigated. The main fatty acids in paprika seed oils were linoleic acid (69.5,74.7,g/100,g), oleic acid (8.9,12.5,g/100,g) and palmitic acid (10.7,14.2,g/100,g). The oils contained an appreciable amount of ,-tocopherol (306.6,602.6,mg/kg), followed by ,-tocopherol (7.3,148.7,mg/kg). The major sterols were ,-sitosterol (1571.4,4061.7,mg/kg), campesterol (490.8,1182.7,mg/kg), and ,5 -avenasterol (374.5,899.6,mg/kg). The total concentration of sterols ranged from 3134.0,mg/kg to 7233.7,mg/kg. Remarkable amounts of cholesterol were found in the different samples (164.6,491.0,mg/kg). The present study showed that paprika seeds are a potential source of valuable oil that could be used for edible and industrial applications. [source] Supercritical extraction of borage seed oil coupled to conventional solvent extraction of antioxidantsEUROPEAN JOURNAL OF LIPID SCIENCE AND TECHNOLOGY, Issue 11 2008Carmen Soto Abstract This paper describes the extraction of borage seed oil by supercritical carbon dioxide (SC-CO2) and the further extraction of antioxidants from the SC-CO2 -defatted borage meal with organic solvents (water, methanol, ethanol and ethyl acetate). The optimal conditions for oil extraction were obtained at 303 and 323,K at 200,bar, 2.5,h and a continuous flow of CO2 of 1.5,L/h introduced through the bottom when the operating pressure and temperature were reached, attaining a yield of 60%. Borage oil is rich in unsaturated fatty acids; oleic acid, linoleic acid and linolenic acid accounted for 74% of the total fatty acid content under the above conditions. The highest extraction yield was achieved using water or methanol as extracting solvent from the SC-CO2 -defatted borage meal at 303,K and pressures of 200 and 150,bar for water and methanol, respectively. The most potent extracts, according to all methods tested, were obtained with water and methanol. [source] Behaviours of pulmonary sensory receptors during development of acute lung injury in the rabbitEXPERIMENTAL PHYSIOLOGY, Issue 4 2007Shuxin Lin We tested the hypothesis that oleic acid-induced acute lung injury activates pulmonary nociceptors, that is, C fibre receptors (CFRs) and high-threshold A, fibre receptors (HTARs). Single-unit activity was recorded in the cervical vagus nerve and assessed before and after injecting oleic acid (75 ,l kg,1i.v.) into anaesthetized, open-chest, mechanically ventilated rabbits. Unit activities increased within seconds and peaked within a few minutes (from 0.3 ± 0.1 to 1.4 ± 0.9 impulses s,1 for CFRs and from 0.5 ± 0.1 to 1.7 ± 0.3 impulses s,1 for HTARs, both n= 8 and P < 0.05). These activities were sustained while pulmonary oedema developed and dynamic lung compliance decreased over the 90 min observation period. Activities in slowly adapting receptors and rapidly adapting receptors were also increased; however, their responsiveness to airway pressure stimulation decreased progressively. We conclude that pulmonary nociceptors are stimulated during acute lung injury. The dual nociceptor system, consisting of both non-myelinated CFRs and myelinated HTARs, may play an important role in the pathophysiological process of acute lung injury-induced respiratory responses. [source] Characterization of a hemocyte intracellular fatty acid-binding protein from crayfish (Pacifastacus leniusculus) and shrimp (Penaeus monodon)FEBS JOURNAL, Issue 13 2006Irene Söderhäll Intracellular fatty acid-binding proteins (FABPs) are small members of the superfamily of lipid-binding proteins, which occur in invertebrates and vertebrates. Included in this superfamily are the cellular retinoic acid-binding proteins and retinol-binding proteins, which seem to be restricted to vertebrates. Here, we report the cDNA cloning and characterization of two FABPs from hemocytes of the freshwater crayfish Pacifastacus leniusculus and the shrimp Penaeus monodon. In both these proteins, the binding triad residues involved in interaction with ligand carboxylate groups are present. From the sequence and homology modeling, the proteins are probably FABPs and not retinoic acid-binding proteins. The crayfish transcript (plFABP) was detected at high level in hemocytes, hepatopancreas, intestine and ovary and at low level in hematopoietic tissue and testis. Its expression in hematopoietic cells varied depending on the state of the crayfish from which it was isolated. Expression was 10,15 times higher in cultures isolated from crayfish with red colored plasma, in which hemocyte synthesis was high, if retinoic acid was added to the culture medium. In normal colored crayfish, with normal levels of hemocytes, no increase in expression of p1FABP was detected. Two other putative plFABP ligands, stearic acid and oleic acid, did not have any effect on plFABP expression in hematopoietic cells. These results suggest that retinoic acid-dependent signaling may be present in crustaceans. [source] A folding variant of human ,-lactalbumin induces mitochondrial permeability transition in isolated mitochondriaFEBS JOURNAL, Issue 1 2001Camilla Köhler A human milk fraction containing multimeric ,-lactalbumin (MAL) is able to kill cells via apoptosis. MAL is a protein complex of a folding variant of ,-lactalbumin and lipids. Previous results have shown that upon treatment of transformed cells, MAL localizes to the mitochondria and cytochrome c is released into the cytosol. This is followed by activation of the caspase cascade. In this study, we further investigated the involvement of mitochondria in apoptosis induced by the folding variant of ,-lactalbumin. Addition of MAL to isolated rat liver mitochondria induced a loss of the mitochondrial membrane potential (,,m), mitochondrial swelling and the release of cytochrome c. These changes were Ca2+ -dependent and were prevented by cyclosporin A, an inhibitor of mitochondrial permeability transition. MAL also increased the rate of state 4 respiration in isolated mitochondria by exerting an uncoupling effect. This effect was due to the presence of fatty acids in the MAL complex because it was abolished completely by BSA. BSA delayed, but failed to prevent, mitochondrial swelling as well as dissipation of ,,m, indicating that the fatty acid content of MAL facilitated, rather than caused, these effects. Similar results were obtained with HAMLET (human ,-lactalbumin made lethal to tumour cells), which is native ,-lactalbumin converted in vitro to the apoptosis-inducing folding variant of the protein in complex with oleic acid. Our findings demonstrate that a folding variant of ,-lactalbumin induces mitochondrial permeability transition with subsequent cytochrome c release, which in transformed cells may lead to activation of the caspase cascade and apoptotic death. [source] Magnetically Controllable Silver Nanocomposite with Multifunctional Phosphotriazine Matrix and High Antimicrobial ActivityADVANCED FUNCTIONAL MATERIALS, Issue 14 2010Panagiotis Dallas Abstract A recently developed multi-functional phosphotriazine-based polymer is used as a matrix for embedding ,-Fe2O3 nanoparticles as well as a suitable chemical template for surface modification with silver nanoparticles. For the primary magnetic modification, maghemite nanoparticles are surface modified with oleic acid in order to render them organophilic and to prevent the aggregation of the nanoparticles. This aggregation could occur as the polymer synthesis, based on reaction of phosphonitrilic chlorine and 1,4-phenylenediamine, takes place in toluene. The surface active amine units of the polymer structure enable the reduction of silver cations to silver nanoparticles, which are well attached and finely dispersed on its surface. The developed nanocomposite represents one of the few magnetically controllable antibacterial agents based on silver nanoparticles. Magnetic measurements reveal the completely suppressed interactions among maghemite nanoparticles because of their perfect surface coating with an organic surfactant and fine dispersion inside the polymer matrix. This magnetic nanocomposite exhibits a high antibacterial and antifungal activity as proven by tests with nine bacterial strains and four candida (yeast genus) species. For the majority of the tested species, the minimum-inhibition concentrations are below 100,mg,L,1, which is comparable to their equivalent minimum-inhibition concentrations in colloidal silver systems. [source] Molecular monitoring of microbial diversity in expanded granular sludge bed (EGSB) reactors treating oleic acidFEMS MICROBIOLOGY ECOLOGY, Issue 2 2002Maria Alcina Pereira Abstract A molecular approach was used to evaluate the microbial diversity of bacteria and archaea in two expanded granular sludge bed (EGSB) reactors fed with increasing oleic acid loading rates up to 8 kg of chemical oxygen demand (COD) m,3 day,1 as the sole carbon source. One of the reactors was inoculated with granular sludge (RI) and the other with suspended sludge (RII). During operation, the sludge in both reactors was segregated in two layers: a bottom settled one and a top floating one. The composition of the bacterial community, based on 16S rDNA sequence diversity, was affected most during the oleate loading process in the two reactors. The archaeal consortium remained rather stable over operation in RI, whereas in RII the relative abundance of Methanosaeta -like organisms became gradually weaker, starting in the bottom layer. In the range of oleate loads evaluated, 6 kg of COD m,3 day,1 was found as the maximum value that could be applied to the system. A further increase to 8 kg of oleate-COD m,3 day,1 induced a maximal shift on the microbial structure of the sludges. At this time point, methanogenic acetoclastic activity was not detected and only very low methanogenic activity on H2/CO2 was exhibited by the sludges. [source] SOA genes encode proteins controlling lipase expression in response to triacylglycerol utilization in the yeast Yarrowia lipolyticaFEMS YEAST RESEARCH, Issue 1 2010Thomas Desfougčres Abstract The oleaginous yeast Yarrowia lipolytica efficiently metabolizes hydrophobic substrates such as alkanes, fatty acids or triacylglycerol. This yeast has been identified in oil-polluted water and in lipid-rich food. The enzymes involved in lipid breakdown, for use as a carbon source, are known, but the molecular mechanisms controlling the expression of the genes encoding these enzymes are still poorly understood. The study of mRNAs obtained from cells grown on oleic acid identified a new group of genes called SOA genes (specific for oleic acid). SOA1 and SOA2 are two small genes coding for proteins with no known homologs. Single- and double-disrupted strains were constructed. Wild-type and mutant strains were grown on dextrose, oleic acid and triacylglycerols. The double mutant presents a clear phenotype consisting of a growth defect on tributyrin and triolein, but not on dextrose or oleic acid media. Lipase activity was 50-fold lower in this mutant than in the wild-type strain. The impact of SOA deletion on the expression of the main extracellular lipase gene (LIP2) was monitored using a LIP2 -,-galactosidase promoter fusion protein. These data suggest that Soa proteins are components of a molecular mechanism controlling lipase gene expression in response to extracellular triacylglycerol. [source] Clean and Flexible Modification Strategy for Carboxyl/Aldehyde-Functionalized Upconversion Nanoparticles and Their Optical ApplicationsADVANCED FUNCTIONAL MATERIALS, Issue 24 2009Huan-Ping Zhou Abstract Rare-earth upconversion nanoparticles (UCNPs) exhibit great potential in luminescent biolabels and other multifunctional probes; however, their applications are limited by their low water solubility and the lack of binding groups. To address these problems, a clean and flexible strategy to modify hydrophobic monodisperse UCNPs into hydrophilic ones that are capped with functional groups is developed. The modification process is implemented by direct oxidation of oleic acid ligands with ozone under specific conditions, where the oleic acid (OA) ligands on the surface of the UCNPs can be converted into azelaic acid ligands (HOOC(CH2)7COOH) or azelaic aldehyde HOOC(CH2)7CHO, as is revealed by Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) measurements. This oxidation process has no significant side-effects on the morphology, phase, composition, or luminescent properties of the UCNPs. Free carboxylic acid groups on the surface endow the UCNPs with good water solubility, while aldehyde groups at the surface provide binding sites for amino-containing molecules via Schiff-base condensation, such as 2-(4-aminophenylethylyl)-5-methoxy-2-(2-pyridyl)thiazole (MPTEA) and 2-aminoethanethiol hydrochloride (NH2CH2CH2SH·HCl, HEMA). A Ce4+ sensor is constructed based on the dual-emission arising from the different spectral responses of MPTEA and the UCNPs. Facilitated by the covalent linkage between the terminal aldehyde group on the UCNPs and the amino group in HEMA, a hybrid structure of UCNPs and Au NPs is fabricated. The effective coupling between the aldehyde group and the amino group suggests that these functionalized UCNPs have potential in combining other functional units for simultaneous biolabeling, or other optical applications. [source] The Active-Core/Active-Shell Approach: A Strategy to Enhance the Upconversion Luminescence in Lanthanide-Doped NanoparticlesADVANCED FUNCTIONAL MATERIALS, Issue 18 2009Fiorenzo Vetrone Abstract Nanoparticles of NaGdF4 doped with trivalent erbium (Er3+) and ytterbium (Yb3+) are prepared by a modified thermal decomposition synthesis from trifluoroacetate precursors in 1-octadecene and oleic acid. The nanoparticles emit visible upconverted luminescence on excitation with near-infrared light. To minimize quenching of this luminescence by surface defects and surface-associated ligands, the nanoparticles are coated with a shell of NaGdF4. The intensity of the upconversion luminescence is compared for nanoparticles that were coated with an undoped shell (inert shell) and similar particles coated with a Yb3+ -doped shell (active shell). Luminescence is also measured for nanoparticles lacking the shell (core only), and doped with Yb3+ at levels corresponding to the doped and undoped core/shell materials respectively. Upconversion luminescence was more intense for the core/shell materials than for the uncoated nanoparticles, and is greatest for the materials having the "active" doped shell. Increasing the Yb3+ concentration in the "core-only" nanoparticles decreases the upconversion luminescence intensity. The processes responsible for the upconversion are presented and the potential advantages of "active-core"/"active-shell" nanoparticles are discussed. [source] Superparamagnetic Hyperbranched Polyglycerol-Grafted Fe3O4 Nanoparticles as a Novel Magnetic Resonance Imaging Contrast Agent: An In Vitro AssessmentADVANCED FUNCTIONAL MATERIALS, Issue 16 2009Liang Wang Abstract Hyperbranched polyglycerol-grafted, magnetic Fe3O4 nanoparticles (HPG-grafted MNPs) are successfully synthesized by surface-initiated ring-opening multibranching polymerization of glycidol. Reactive hydroxyl groups are immobilized on the surface of 6,9,nm Fe3O4 nanoparticles via effective ligand exchange of oleic acid with 6-hydroxy caproic acid. The surface hydroxyl groups are treated with aluminum isopropoxide to form the nanosized macroinitiators. The successful grafting of HPG onto the nanoparticles is confirmed by infrared and X-ray photoelectron spectroscopy. The HPG-grafted MNPs have a uniform hydrodynamic diameter of (24.0,±,3.0) nm, and are very stable in aqueous solution, as well as in cell culture medium, for months. These nanoparticles have great potential for application as a new magnetic resonance imaging contrast agent, as evidenced by their lack of cytotoxicity towards mammalian cells, low uptake by macrophages, excellent stability in aqueous medium and magnetic fields, and favorable magnetic properties. Furthermore, the possibility of functionalizing the hydroxyl end-groups of the HPG with cell-specific targeting ligands will expand the range of applications of these MNPs. [source] Labeling of Adipose-Derived Stem Cells by Oleic-Acid-Modified Magnetic NanoparticlesADVANCED FUNCTIONAL MATERIALS, Issue 8 2009Lian Cen Abstract The in vivo tracking of adipose derived stem cells (ASCs) is of essential concern when they are used as seed cells in tissue engineering. This study explores the feasibility of using magnetic nanoparticles (MNs), a type of contrast agents in magnetic resonance imaging (MRI), to label ASCs such that the labeled ASCs could be tracked in vivo by MRI non-invasively and repeatedly. To do this, MNs of <10,nm surface-coated with oleic acid are synthesized via a high-temperature solution-phase reaction. Cytotoxicity of the as-synthesized MNs at concentrations up to 0.1,mg,mL,1 on 104,cells,mL,1 ASCs is evaluated by LDH release. Since only minor cytotoxicity is detected, the effects of the labeling technique on cellular behaviors and uptake by labeled cells are investigated. Cell proliferation and differentiation with and without MNs are compared. The results show that proliferation of ASCs (104,cells,mL,1) labeled by MNs (0.05,mg,mL,1) is significantly enhanced and dependent on the labeling time. The MNs are located in the vesicles within cytoplasm of ASCs. The cellular uptake reaches as high as ,180,pg/cell. Nevertheless, the labeled ASCs still maintained adipogenic and osteogenic differentiation. Hence, the feasibility of labeling ASCs by oleic acid coated MNs is ascertained and it was better to label the cells during their quiescent stage. The labeled ASCs can also be in vivo detected by MRI in a subcutaneous model in vivo. Further MRI tracking of the labeled ASCs in long-term follow-up would thus follow this current study. [source] UV-Light-Driven Immobilization of Surface-Functionalized Oxide Nanocrystals onto Silicon,ADVANCED FUNCTIONAL MATERIALS, Issue 2 2007E. Fanizza Abstract TiO2 nanorods (NRs) and ,-Fe2O3 nanocrystals (NCs) passivated with unsaturated long-chain carboxylic acids, namely 10-undecylenic acid (10UDA) and oleic acid (OLEA), are covalently anchored to Si(100) at room temperature by UV-light-driven reaction of hydrogenated silicon with the carbon,carbon double bond (,CC,) moieties of the capping surfactants. The high reactivity of vinyl groups towards Si provides a general tool for attaching particles of both materials via Si,C bonds. Interestingly, TiO2 NRs were efficiently attached to silicon even when capped by OLEA. This latter finding has been explained by a photocatalytic mechanism involving the primary role of hydroxyl radicals that can be generated upon bandgap TiO2 photoexcitation with UV light. The increased oxide coverage achievable on Si opens access to further surface manipulation, as demonstrated by the possibility of depositing an additional film of Au nanoparticles onto TiO2 via TiO2 -catalyzed visible-light-driven reduction of aqueous AuCl4, ions. Extensive morphological and chemical characterization of the obtained NC-functionalized Si substrates is provided to support the effectiveness of proposed photochemical approaches. [source] Organotins-promoted peroxidation of unsaturated fatty acids: A new antioxidative scavenger for promotersHETEROATOM CHEMISTRY, Issue 6 2006Elena R. Milaeva The organotin compounds RnSnX4- n are promoters of lipids peroxidation. The influence of (CH3)2SnCl2, (C2H5)2SnCl2, and SnCl2 upon the radical chain oxidation of oleic acid as model substrate R,H for lipid peroxidation in the simultaneous presence of porphyrins (free bases of meso -tetrakis(3,5-di- tert -butyl-4-hydroxyphenyl)porphyrin (R,4PH2) and of meso -tetraphenylporphyrin (TPPH2)) has been studied. The monitoring of the unsaturated acid peroxidation level has been performed by the determination of the total concentration of isomeric hydroperoxides as well as of the thiobarbituric acid reactive substances, as markers of carbonyl compounds formation following the hydroperoxides decomposition. The organotin compounds demonstrate prooxidative activity. The promoting effect of these compounds decreases in the presence of TPPH2. The free-base porphyrin R,4PH2, containing the antioxidative phenolic moieties (2,6-di- tert -butylphenol), demonstrates the acute inhibitory effect upon the acid's peroxidation. The analogous results have been achieved when compared with the influence of CH3HgI and HgCl2 upon the acids peroxidation of oleic acid in the presence of porphyrins. This fact points out that meso- tetrakis(3,5-di- tert -butyl-4-hydroxyphenyl)porphyrin shows the activities of both the antioxidant and of the scavenger for metals and might be used as a new antioxidative scavenger preventing lipids peroxidation. © 2006 Wiley Periodicals, Inc. Heteroatom Chem 17:475,480, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20269 [source] The fatty acid compositions of predator Piocoris luridus (Heteroptera: Lygaeidae) and its host Monosteria unicostata (Heteroptera: Tingidae) reared on almondINSECT SCIENCE, Issue 6 2007OZLEM CAKMAK Abstract The changes in fatty acid compositions during nutritional interaction among almond Amygdalus communis Linnaeus (Rosales: Rosaceae) (host plant), lacebug Monosteria unicostata (Mulsant and Rey) (Heteroptera: Tingidae) and its predator Piocoris luridus Fieber (Heteroptera: Lygaeidae) were determined by gas chromatography and gas chromatography-mass spectrometry analyses. The fatty acid profiles of phospholipids and triacylglycerols were substantially different. Unlike the general observations for virtually most terrestrial insects, arachidonic and eicosapentaenoic acids were detected in high proportions of phospholipid fractions in both insects, especially in P. luridus. Also the almond tissues provide very little oleic acid to the herbivore diet, yet both insect species developed high proportions of this component. Our data reveals instances of specific accumulation of fatty acid biosynthesis, elongation/desaturation, and not incorporating selected fatty acids into cellular lipids. [source] Dispersible Ferromagnetic FePt NanoparticlesADVANCED MATERIALS, Issue 8 2009Jaemin Kim A simple method to produce ferromagnetic FePt nanoparticle dispersions by thermal annealing of core/shell-structured FePt/MgO nanoparticles and removal of MgO in the presence of hexadecanethiol and oleic acid is reported. The ferromagnetic FePt nanoparticles have a room temperature coercivity of 1 T and magnetization of 56.4 emu per gram of FePt, and are suitable for single-particle magnetism studies and other magnetic applications. [source] Radiographic lung density assessed by computed tomography is associated with extravascular lung water contentACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 8 2010V. V. KUZKOV Background: We hypothesized that in acute lung injury (ALI), the volume of pulmonary tissue with aqueous density, as determined by spiral computed tomography (CT), is associated with extravascular lung water content. Our aim was to compare tissue volume index, as assessed by CT, before and after oleic acid-induced ALI, with extravascular lung water indexes (EVLWI), determined with single transpulmonary thermodilution (EVLWISTD), thermal-dye dilution (EVLWITDD), and postmortem gravimetry (EVLWIG). Methods: Seven instrumented sheep received an intravenous infusion of oleic acid 0.08 ml/kg (OA group) and four animals had vehicle only (Control group). The day before, and immediately after the experiment, sheep were anesthetized to undergo quantitative CT examinations during a short breath hold. Hemodynamics, oxygenation, EVLWISTD, and EVLWTDD were registered. Linear regression analysis was used to assess the relationships between EVLWISTD, EVLWTDD, EVLWIG, and lung tissue volume index (TVICT) determined with CT. Results: In the OA group, total lung volume increased compared with Controls. Poorly and non-aerated lung volumes increased a 3.6- and 4.9-fold, respectively, and TVICT almost doubled. EVLWISTD, EVLWITDD, and TVICT were associated significantly with EVLWIG (r=0.85, 0.90, and 0.88, respectively; P<0.001). TVICT deviated from the reference EVLWIG values to the greatest extent with a mean bias ± 2SD of 4.0 ± 6.0 ml/kg. Conclusions: In ovine oleic acid-induced ALI, lung tissue volume, as assessed by quantitative CT, is in close agreement with EVLWI, as determined by indicator dilution methods and postmortem gravimetry, but overestimates lung fluid content. [source] | |||||||||||||||||||||||||