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Sample records for octadecyl glyceryl ether-alpha

  1. Final report of the amended safety assessment of Glyceryl Laurate, Glyceryl Laurate SE, Glyceryl Laurate/Oleate, Glyceryl Adipate, Glyceryl Alginate, Glyceryl Arachidate, Glyceryl Arachidonate, Glyceryl Behenate, Glyceryl Caprate, Glyceryl Caprylate, Glyceryl Caprylate/Caprate, Glyceryl Citrate/Lactate/Linoleate/Oleate, Glyceryl Cocoate, Glyceryl Collagenate, Glyceryl Erucate, Glyceryl Hydrogenated Rosinate, Glyceryl Hydrogenated Soyate, Glyceryl Hydroxystearate, Glyceryl Isopalmitate, Glyceryl Isostearate, Glyceryl Isostearate/Myristate, Glyceryl Isostearates, Glyceryl Lanolate, Glyceryl Linoleate, Glyceryl Linolenate, Glyceryl Montanate, Glyceryl Myristate, Glyceryl Isotridecanoate/Stearate/Adipate, Glyceryl Oleate SE, Glyceryl Oleate/Elaidate, Glyceryl Palmitate, Glyceryl Palmitate/Stearate, Glyceryl Palmitoleate, Glyceryl Pentadecanoate, Glyceryl Polyacrylate, Glyceryl Rosinate, Glyceryl Sesquioleate, Glyceryl/Sorbitol Oleate/Hydroxystearate, Glyceryl Stearate/Acetate, Glyceryl Stearate/Maleate, Glyceryl Tallowate, Glyceryl Thiopropionate, and Glyceryl Undecylenate.

    PubMed

    2004-01-01

    The safety of 43 glyceryl monoesters listed as cosmetic ingredients was reviewed in a safety assessment completed in 2000. Additional safety test data pertaining to Glyceryl Rosinate and Glyceryl Hydrogenated Rosinate were received and served as the basis for this amended report. Glyceryl monoesters are used mostly as skin-conditioning agents--emollients and/or surfactant--emulsifying agents in cosmetics. The following 20 glyceryl monoesters are currently reported to be used in cosmetics: Glyceryl Laurate, Glyceryl Alginate, Glyceryl Arachidonate, Glyceryl Behenate, Glyceryl Caprylate, Glyceryl Caprylate/Caprate, Glyceryl Cocoate, Glyceryl Erucate, Glyceryl Hydroxystearate, Glyceryl Isostearate, Glyceryl Lanolate, Glyceryl Linoleate, Glyceryl Linolenate, Glyceryl Myristate, Glyceryl Oleate/Elaidate, Glyceryl Palmitate, Glyceryl Polyacrylate, Glyceryl Rosinate, Glyceryl Stearate/Acetate, and Glyceryl Undecylenate. Concentration of use data received from the cosmetics industry in 1999 indicate that Glyceryl Monoesters are used at concentrations up to 12% in cosmetic products. Glyceryl Monoesters are not pure monoesters, but are mostly mixtures with mono-, di-, and tri-esters. The purity of commercial and conventional Monoglyceride (Glyceryl Monoester) is a minimum of 90%. Glyceryl Monoesters (monoglycerides) are metabolized to free fatty acids and glycerol, both of which are available for the resynthesis of triglycerides. Glyceryl Laurate enhanced the penetration of drugs through cadaverous skin and hairless rat skin in vitro and has been described as having a wide spectrum of antimicrobial activity. A low-grade irritant response was observed following inhalation of an aerosol containing 10% Glyceryl Laurate by test animals. Glyceryl monoesters have little acute or short-term toxicity in animals, and no toxicity was noted following chronic administration of a mixture consisting mostly of glyceryl di- and mono- esters. Glyceryl Laurate did have strong hemolytic

  2. Amended final report on the safety assessment of glyceryl dilaurate, glyceryl diarachidate, glyceryl dibehenate, glyceryl dierucate, glyceryl dihydroxystearate, glyceryl diisopalmitate, glyceryl diisostearate, glyceryl dilinoleate, glyceryl dimyristate, glyceryl dioleate, glyceryl diricinoleate, glyceryl dipalmitate, glyceryl dipalmitoleate, glyceryl distearate, glyceryl palmitate lactate, glyceryl stearate citrate, glyceryl stearate lactate, and glyceryl stearate succinate.

    PubMed

    2007-01-01

    Glyceryl Dilaurate, Glyceryl Diarachidate, Glyceryl Dibehenate, Glyceryl Dierucate, Glyceryl Dihydroxystearate, Glyceryl Diisopalmitate, Glyceryl Diisostearate, Glyceryl Dilinoleate, Glyceryl Dimyristate, Glyceryl Dioleate, Glyceryl Diricinoleate, Glyceryl Dipalmitate, Glyceryl Dipalmitoleate, Glyceryl Distearate, Glyceryl Palmitate Lactate, Glyceryl Stearate Citrate, Glyceryl Stearate Lactate, and Glyceryl Stearate Succinate are diacylglycerols (also known as diglycerides or glyceryl diesters) that function as skin conditioning agents - emollients in cosmetics. Only Glyceryl Dilaurate (up to 5%), Glyceryl Diisostearate (up to 43%), Glyceryl Dioleate (up to 2%), Glyceryl Distearate (up to 7%), and Glyceryl Stearate Lactate (up to 5%) are reported to be in current use. Production proceeds from fully refined vegetable oils, which are further processed using hydrogenation and fractionation techniques, and the end products are produced by reacting selected mixtures of the partly hydrogenated, partly fractionated oils and fats with vegetable-derived glycerine to yield partial glycerides. In the final stage of the production process, the products are purified by deodorization, which effectively removes pesticide residues and lower boiling residues such as residues of halogenated solvents and aromatic solvents. Diglycerides have been approved by the Food and Drug Administration (FDA) for use as indirect food additives. Nominally, these ingredients are 1,3-diglycerides, but are easily isomerized to the 1,2-diglycerides form. The 1,3-diglyceride isomer is not a significant toxicant in acute, short-term, subchronic, or chronic animal tests. Glyceryl Dilaurate was a mild primary irritant in albino rabbits, but not a skin sensitizer in guinea pig maximization tests. Diacylglycerol Oil was not genotoxic in the Ames test, in mammalian Chinese hamster lung cells, or in a rodent bone marrow micronucleus assay. An eye shadow containing 1.5% Glyceryl Dilaurate did not induce skin

  3. 21 CFR 184.1324 - Glyceryl monostearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Listing of Specific Substances Affirmed as GRAS § 184.1324 Glyceryl monostearate. (a) Glyceryl... esters of fatty acids present in commercial stearic acid. Glyceryl monostearate is prepared by..., of stearic acid that is derived from edible sources. (b) The ingredient must be of a purity...

  4. 21 CFR 184.1324 - Glyceryl monostearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Listing of Specific Substances Affirmed as GRAS § 184.1324 Glyceryl monostearate. (a) Glyceryl... esters of fatty acids present in commercial stearic acid. Glyceryl monostearate is prepared by..., of stearic acid that is derived from edible sources. (b) The ingredient must be of a purity...

  5. Octadecyl ferulate behavior in 1,2-dioleoylphosphocholine liposomes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Octadecyl ferulate, a lipophilic derivative of ferulic acid having antioxidant properties, is found throughout the plant and fungi kingdoms. Octadecyl ferulate was prepared using solid acid catalyst, monitored using supercritical fluid chromatograph and purified to a 42% yield. Differential scanning...

  6. Octadecyl ferulate behavior in 1,2-Dioleoylphosphocholine liposomes

    NASA Astrophysics Data System (ADS)

    Evans, Kervin O.; Compton, David L.; Whitman, Nathan A.; Laszlo, Joseph A.; Appell, Michael; Vermillion, Karl E.; Kim, Sanghoon

    2016-01-01

    Octadecyl ferulate was prepared using solid acid catalyst, monitored using Supercritical Fluid Chromatography and purified to a 42% yield. Differential scanning calorimetry measurements determined octadecyl ferulate to have melting/solidification phase transitions at 67 and 39 °C, respectively. AFM imaging shows that 5-mol% present in a lipid bilayer induced domains to form. Phase behavior measurements confirmed that octadecyl ferulate increased transition temperature of phospholipids. Fluorescence measurements demonstrated that octadecyl ferulate stabilized liposomes against leakage, maintained antioxidant capacity within liposomes, and oriented such that the feruloyl moiety remained in the hydrophilic region of the bilayer. Molecular modeling calculation indicated that antioxidant activity was mostly influenced by interactions within the bilayer.

  7. 21 CFR 172.811 - Glyceryl tristearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.811 Glyceryl tristearate. The food additive glyceryl tristearate may be safely used in food in accordance with the following prescribed conditions: (a) The food additive (CAS Reg....

  8. 21 CFR 184.1323 - Glyceryl monooleate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... prepared by esterification of commerical oleic acid that is derived either from edible sources or from tall oil fatty acids meeting the requirements of § 172.862 of this chapter. It contains glyceryl...

  9. 21 CFR 184.1323 - Glyceryl monooleate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... prepared by esterification of commerical oleic acid that is derived either from edible sources or from tall oil fatty acids meeting the requirements of § 172.862 of this chapter. It contains glyceryl...

  10. 21 CFR 184.1323 - Glyceryl monooleate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... prepared by esterification of commerical oleic acid that is derived either from edible sources or from tall oil fatty acids meeting the requirements of § 172.862 of this chapter. It contains glyceryl...

  11. 21 CFR 184.1323 - Glyceryl monooleate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... esterification of commerical oleic acid that is derived either from edible sources or from tall oil fatty acids.... No. 25496-72-4) and glyceryl esters of fatty acids present in commercial oleic acid. (b)...

  12. 21 CFR 184.1323 - Glyceryl monooleate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... commerical oleic acid that is derived either from edible sources or from tall oil fatty acids meeting the...) and glyceryl esters of fatty acids present in commercial oleic acid. (b) The ingredient must be of...

  13. Monolithic stationary phases with incorporated fumed silica nanoparticles. Part II. Polymethacrylate-based monolithic column with "covalently" incorporated modified octadecyl fumed silica nanoparticles for reversed-phase chromatography.

    PubMed

    Aydoğan, Cemil; El Rassi, Ziad

    2016-05-06

    This study is concerned with the incorporation of surface modified fumed silica nanoparticles (FSNPs) into polymethacrylate based monolithic columns for use in reversed phase chromatography (RPC) of small solutes and proteins. First, FSNPs were modified with 3-(trimethoxysilyl)propylmethacrylate (TMSPM) to yield the "hybrid" methacryloyl fumed silica nanoparticle (MFSNP) monomer. The resulting MFSNP was then mixed with glyceryl monomethacrylate (GMM) and ethylene dimethacrylate (EDMA) in a binary porogenic solvent composed of cyclohexanol and dodecanol, and the in situ copolymerization of MFSNP, GMM and EDMA was performed in a stainless steel column of 4.6 mm i.d. The silanol groups of the hybrid monolith thus obtained were grafted with octadecyl ligands by perfusing the hybrid monolithic column with a solution of 4% w/v of dimethyloctadecylchlorosilane (DODCS) in toluene while the column was maintained at 110°C for 6h (in a heated HPLC oven). One of the originalities of this study was to demonstrate MFSNP as a novel derivatized "hybrid monomer" in making RPC monolithic columns with surface bound octadecyl ligands. In this respect, the RPC behavior of the monolithic column with "covalently" incorporated FNSPs having surface grafted octadecyl ligands was evaluated with alkylbenzenes, aniline derivatives and phenolic compounds. The results showed that the hybrid poly(GMA-EDMA-MFSNP) having surface bound octadecyl ligands exhibited hydrophobic interactions under reversed phase elution conditions. Furthermore, six standard proteins were baseline separated on the column using a 10min linear gradient elution at increasing ACN concentration in the mobile phase at a flow rate of 1.0mL/min using a 10 cm×4.6mm i.d. column. The relative standard deviations (RSDs) for the retention times of the tested solutes were lower than 2.1% and 2.4% under isocratic elution and gradient elution conditions, respectively.

  14. 21 CFR 184.1329 - Glyceryl palmitostearate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...-, di-, and triglycerides of palmitic acid and stearic acid. (2) Heavy metals (as lead): Not more than... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Glyceryl palmitostearate. 184.1329 Section 184.1329 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  15. 21 CFR 184.1328 - Glyceryl behenate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Iodine number. Not more than 3. (6) Heavy metals (as Pb). Not more than 10 parts per million. (c) In... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Glyceryl behenate. 184.1328 Section 184.1328 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  16. 21 CFR 184.1329 - Glyceryl palmitostearate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... substance is a mixture of mono-, di-, and triglycerides of palmitic acid and stearic acid. (2) Heavy metals... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Glyceryl palmitostearate. 184.1329 Section 184.1329 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  17. 21 CFR 184.1329 - Glyceryl palmitostearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... substance is a mixture of mono-, di-, and triglycerides of palmitic acid and stearic acid. (2) Heavy metals... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Glyceryl palmitostearate. 184.1329 Section 184.1329 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED)...

  18. 21 CFR 184.1328 - Glyceryl behenate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ...) Iodine number. Not more than 3. (6) Heavy metals (as Pb). Not more than 10 parts per million. (c) In... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Glyceryl behenate. 184.1328 Section 184.1328 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  19. 21 CFR 184.1329 - Glyceryl palmitostearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... substance is a mixture of mono-, di-, and triglycerides of palmitic acid and stearic acid. (2) Heavy metals... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Glyceryl palmitostearate. 184.1329 Section 184.1329 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  20. 21 CFR 184.1328 - Glyceryl behenate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ...) Iodine number. Not more than 3. (6) Heavy metals (as Pb). Not more than 10 parts per million. (c) In... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Glyceryl behenate. 184.1328 Section 184.1328 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  1. 21 CFR 184.1328 - Glyceryl behenate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ...) Iodine number. Not more than 3. (6) Heavy metals (as Pb). Not more than 10 parts per million. (c) In... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Glyceryl behenate. 184.1328 Section 184.1328 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD...

  2. 21 CFR 184.1329 - Glyceryl palmitostearate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... substance is a mixture of mono-, di-, and triglycerides of palmitic acid and stearic acid. (2) Heavy metals... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Glyceryl palmitostearate. 184.1329 Section 184.1329 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES...

  3. 21 CFR 184.1328 - Glyceryl behenate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ...) Heavy metals (as Pb). Not more than 10 parts per million. (c) In accordance with § 184.1(b)(1) of this... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Glyceryl behenate. 184.1328 Section 184.1328 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED)...

  4. Topical glyceryl trinitrate as adjunctive treatment in Raynaud's disease.

    PubMed

    Franks, A G

    1982-01-09

    The effects of topical glyceryl trinitrate in Raynaud's disease were compared with those of placebo in a double-blind, crossover trial in 17 patients with bilateral Raynaud's disease and an associated collagen disease, who were receiving oral sympatholytic agents at the maximum levels they could tolerate. 1% glyceryl trinitrate ointment or a placebo of lanolin was applied to one hand only for 6 weeks, then patients changed to the other preparation for 6 weeks. The results were evaluated every 2 weeks. The frequency of attacks, severity of attacks, and size of ulcers in the treated hand were significantly lower when the patients were using glyceryl trinitrate ointment than when they were using placebo. The treatment of Raynaud's disease may be improved by using topical glyceryl trinitrate ointment as an adjunct to a basic regimen of oral sympatholytic agents. Glyceryl trinitrate ointment may obviate the need for more aggressive treatment, such as intraarterial reserpine, in selected patients.

  5. 21 CFR 172.852 - Glyceryl-lacto esters of fatty acids.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Glyceryl-lacto esters of fatty acids. 172.852... HUMAN CONSUMPTION Multipurpose Additives § 172.852 Glyceryl-lacto esters of fatty acids. Glyceryl-lacto esters of fatty acids (the lactic acid esters of mono- and diglycerides) may be safely used in food...

  6. 21 CFR 172.852 - Glyceryl-lacto esters of fatty acids.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Glyceryl-lacto esters of fatty acids. 172.852... HUMAN CONSUMPTION Multipurpose Additives § 172.852 Glyceryl-lacto esters of fatty acids. Glyceryl-lacto esters of fatty acids (the lactic acid esters of mono- and diglycerides) may be safely used in food...

  7. 21 CFR 172.852 - Glyceryl-lacto esters of fatty acids.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Glyceryl-lacto esters of fatty acids. 172.852... HUMAN CONSUMPTION Multipurpose Additives § 172.852 Glyceryl-lacto esters of fatty acids. Glyceryl-lacto esters of fatty acids (the lactic acid esters of mono- and diglycerides) may be safely used in food...

  8. 21 CFR 172.852 - Glyceryl-lacto esters of fatty acids.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Glyceryl-lacto esters of fatty acids. 172.852... HUMAN CONSUMPTION Multipurpose Additives § 172.852 Glyceryl-lacto esters of fatty acids. Glyceryl-lacto esters of fatty acids (the lactic acid esters of mono- and diglycerides) may be safely used in food...

  9. 21 CFR 172.852 - Glyceryl-lacto esters of fatty acids.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Glyceryl-lacto esters of fatty acids. 172.852... § 172.852 Glyceryl-lacto esters of fatty acids. Glyceryl-lacto esters of fatty acids (the lactic acid esters of mono- and diglycerides) may be safely used in food in accordance with the following...

  10. Biodegradation of glyceryl trinitrate by Penicillium corylophilum Dierckx.

    PubMed Central

    Zhang, Y Z; Sundaram, S T; Sharma, A; Brodman, B W

    1997-01-01

    Penicillium corylophilum Dierckx, isolated from a contaminated water wet, double-base propellant, was able to completely degrade glyceryl trinitrate (GTN) in a buffered medium (pH 7.0) containing glucose and ammonium nitrate. In the presence of 12 mg of initial fungal inoculum, GTN (48.5 to 61.6 mumol) was quantitatively transformed in a stepwise process to glyceryl dinitrate (GDN) and glyceryl mononitrate (GMN) within 48 h followed by a decrease in the GDN content with a concomitant increase in the GMN level. GDN was totally transformed to GMN within 168 h, and the complete degradation of GMN was achieved within 336 h. The presence of glucose and ammonium nitrate in the growth medium was essential for completion of the degradation of GTN and its metabolites. Complete degradation of GTN by a fungal culture has not been previously reported in the literature. PMID:9143106

  11. Formation of inclusion complexes between high amylose starch and octadecyl ferulate via steam jet cooking.

    PubMed

    Kenar, James A; Compton, David L; Little, Jeanette A; Peterson, Steve C

    2016-04-20

    Amylose-ligand inclusion complexes represent an interesting approach to deliver bioactive molecules. However, ferulic acid has been shown not to form single helical inclusion complexes with amylose from high amylose maize starch. To overcome this problem a lipophilic ferulic acid ester, octadecyl ferulate, was prepared and complexed with amylose via excess steam jet cooking. Jet-cooking octadecyl ferulate and high amylose starch gave an amylose-octadecyl ferulate inclusion complex in 51.0% isolated yield. X-ray diffraction (XRD) and differential scanning calorimetry (DSC) confirmed that a 61 V-type inclusion complex was formed. Amylose and extraction assays showed the complex to be enriched in amylose (91.9±4.3%) and contain 70.6±5.6mgg(-1) octadecyl ferulate, although, minor hydrolysis (∼4%) of the octadecyl ferulate was observed under the excess steam jet-cooking conditions utilized. This study demonstrates that steam jet cooking is a rapid and scalable process in which to prepare amylose-octadecyl ferulate inclusion complexes.

  12. Formation of the NO donors glyceryl mononitrate and glyceryl mononitrite from the reaction of peroxynitrite with glycerol.

    PubMed

    White, C R; Moellering, D; Patel, R P; Kirk, M; Barnes, S; Darley-Usmar, V M

    1997-12-01

    Peroxynitrite (ONOO-), formed from the rapid reaction of superoxide (O2-.) with NO, is known to generate stable compounds capable of donating NO on reaction with thiols and molecules containing hydroxy groups. Using glycerol as a model compound for the reactions of ONOO- with biomolecules containing hydroxy groups, we separated the products and identified them by HPLC/MS. It was shown that both glyceryl mononitrate and glyceryl mononitrite were formed and released NO on incubation with copper and l-cysteine. The compounds were stable over a period of 4h when shielded from light and kept on ice. Slow spontaneous decomposition occurred in the buffer used for the bioassay, but this was not sufficient to explain the vasorelaxing properties of these NO donors. It is concluded that the stable organic nitrate and nitrite have the capacity to be metabolized by vascular tissues, resulting in vasorelaxation.

  13. Formation of inclusion complexes between high amylose starch and octadecyl ferulate via steam jet cooking

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Amylose can form inclusion complexes with guest molecules and represents an interesting approach to deliver bioactive molecules. However, ferulic acid has been shown not to form single helical inclusion complexes with amylose. To overcome this problem a ferulic acid ester, octadecyl ferulate, posses...

  14. 21 CFR 178.3505 - Glyceryl tri-(12-acetoxy-stearate).

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) INDIRECT FOOD ADDITIVES: ADJUVANTS, PRODUCTION AIDS, AND SANITIZERS Certain Adjuvants and Production Aids § 178.3505 Glyceryl tri-(12-acetoxy-stearate). Glyceryl tri-(12-acetoxystearate) (CAS Reg. No. 139-43-5) may be safely used as a component of articles...

  15. Glyceryl ether monooxygenase resembles aromatic amino acid hydroxylases in metal ion and tetrahydrobiopterin dependence.

    PubMed

    Watschinger, Katrin; Keller, Markus A; Hermetter, Albin; Golderer, Georg; Werner-Felmayer, Gabriele; Werner, Ernst R

    2009-01-01

    Glyceryl ether monooxygenase is a tetrahydrobiopterin-dependent membrane-bound enzyme which catalyses the cleavage of lipid ethers into glycerol and the corresponding aldehyde. Despite many different characterisation and purification attempts, so far no gene and primary sequence have been assigned to this enzyme. The seven other tetrahydrobiopterin-dependent enzymes can be divided in the family of aromatic amino acid hydroxylases - comprising phenylalanine hydroxylase, tyrosine hydroxylase and the two tryptophan hydroxylases - and into the three nitric oxide synthases. We tested the influences of different metal ions and metal ion chelators on glyceryl ether monooxygenase, phenylalanine hydroxylase and nitric oxide synthase activity to elucidate the relationship of glyceryl ether monooxygenase to these two families. 1,10-Phenanthroline, an inhibitor of non-heme iron-dependent enzymes, was able to potently block glyceryl ether monooxygenase as well as phenylalanine hydroxylase, but had no effect on inducible nitric oxide synthase. Two tetrahydrobiopterin analogues, N(5)-methyltetrahydrobiopterin and 4-aminotetrahydrobiopterin, had a similar impact on glyceryl ether monooxygenase activity, as has already been shown for phenylalanine hydroxylase. These observations point to a close analogy of the role of tetrahydrobiopterin in glyceryl ether monooxygenase and in aromatic amino acid hydroxylases and suggest that glyceryl ether monooxygenase may require a non-heme iron for catalysis.

  16. Superheated water as chromatographic eluent for parabens separation on octadecyl coated zirconia stationary phase.

    PubMed

    Dugo, Paola; Buonasera, Katia; Crupi, Maria Lucia; Cacciola, Francesco; Dugo, Giovanni; Mondello, Luigi

    2007-05-01

    In this study, the use of pure water at superheated temperatures, between 100 and 200 degrees C, as a mobile phase for RP separation is explored. Instrumental parameters, such as temperature, flow rate, preheating and cooling, have shown significant effects on the quality of the chromatographic peaks. The properties of superheated water as an eluent were investigated by observing the chromatographic behaviour of four parabens on a carbon-clad zirconia (ZR) phase with covalently bonded octadecyl groups. Results were compared with those obtained at 30 degrees C on a silica-based phase with octadecyl groups, using water and ACN as mobile phase. The optimized method was finally applied to analyse parabens in a commercial body cream.

  17. Sublingual glyceryl trinitrate during colonoscopy and terminal ileal intubation: a randomized controlled trial.

    PubMed

    Hill, Patsy-Anne; Panteleimonitis, Sofoklis; McKay, Graham; Watson, Carol; Prach, Andre; Macdonald, Angus

    2017-02-01

    Background and aims Sublingual glyceryl trinitrate has been used as an aid to cannulate the Sphincter of Oddi during endoscopic retrograde cholangiopancreatography. Its role in terminal ileal intubation during colonoscopy is unknown. This study examines the role of sublingual glyceryl trinitrate in terminal ileal intubation during colonoscopy. Methods A triple-blind randomized controlled trial comparing sublingual glyceryl trinitrate (800 µg) vs. placebo (saline) in relation to terminal ileal intubation during colonoscopy was performed. Following caecal intubation, participants received sublingual glyceryl trinitrate/placebo followed by a 2-min observation period before intubation was attempted. Data on time to intubate the terminal ileum and intubation rate were collected. Results A total of 110 patients (age: 58 years (18-75)) were recruited and randomised as per protocol: 54 received sublingual glyceryl trinitrate. Terminal ileal intubation was successful in all patients receiving sublingual glyceryl trinitrate and in 53 (94.6%) of those receiving saline ( p = 0.243: Fischer's exact). The median time taken for ileal intubation after application of spray was 72.5 (7-900) s in the glyceryl trinitrate group compared with 125 (5-900) s in the placebo group ( p = 0.150: Mann-Whitney). There were no major adverse events reported in either group. Conclusions Terminal ileal intubation rates and timing were very good in both groups. Routine sublingual glyceryl trinitrate was not proven to be beneficial in improving terminal ileal intubation or intubation success rates in the hands of experienced colonoscopists. However, trends in this small study might suggest that glyceryl trinitrate could be useful in the hands of less experienced colonoscopists or in difficult terminal ileal intubation cases.

  18. The effect of octadecyl chain immobilization on the hemocompatibility of poly (2-hydroxyethyl methacrylate).

    PubMed

    Fischer, Marion; Baptista, Catarina P; Gonçalves, Inês C; Ratner, Buddy D; Sperling, Claudia; Werner, Carsten; Martins, Cristina L; Barbosa, Mário A

    2012-11-01

    Albumin-scavenging surfaces decorated with n-alkyl chains represent an established strategy for blood-contacting applications. To evaluate this concept, a set of poly (2-hydroxyethyl methacrylate) (pHEMA) films modified with different amounts of octadecyl isocyanate (C18) was investigated in an in vitro hemocompatibility assay using freshly drawn human whole blood. In addition, the hydrogel materials were thoroughly characterized with respect to changes in wettability and elasticity, which accompanied the gradual chemical modification of pHEMA. An increase of the surface C18 content induced enhanced hydrophobicity and stiffness. Immobilization of C18 chains was found to substantially reduce the coagulation activation and the complement activation by the pHEMA films. Platelet adhesion and degranulation (PF4 release) were similar on the modified and the unmodified pHEMA. Platelet adhesion to pHEMA hydrogels was lower than the polytetrafluoroethylene reference. We conclude that the immobilization of octadecyl chains improved the hemocompatibility of pHEMA materials under conditions that might be encountered in low shear blood flow.

  19. Preparation and optimization of glyceryl behenate-based highly porous pellets containing cilostazol.

    PubMed

    Hwang, Kyu-Mok; Byun, Woojin; Cho, Cheol-Hee; Park, Eun-Seok

    2016-11-03

    The aim of this study was to prepare a highly porous multiparticulate dosage form containing cilostazol for gastroretentive drug delivery. The floating pellets were prepared with glyceryl behenate as a matrix former and camphor as a sublimating agent by extrusion/spheronization and sublimation under vacuum. Granules prepared with sublimation at 60 °C displayed a slower dissolution rate and smoother surface morphology than those prepared at lower temperatures. This was unexpected as the reported melting point of glyceryl behenate is higher than 69 °C. The DSC study revealed that melting began at a lower temperature owing to the multicomponent property of glyceryl behenate, which led to a sintering effect. The prepared pellets were spherical with unimodal size distribution. They also had porous structures with increased porosity, which led to immediate buoyancy. As cilostazol is a hydrophobic drug that has an erosion-based release mechanism, drug release profile was highly correlated with the percentage of disintegrated pellets. Various excipients were added to the glyceryl behenate-based formulation to increase the floating duration. When hydroxyethyl cellulose was added to the glyceryl behenate-based pellets, acceptable dissolution rate and buoyancy were acquired. This system could potentially be used for gastroretentive delivery of various hydrophobic drugs, which was generally considered difficult.

  20. STUDY OF DUAL MATRIX TABLETS CONTAINING HYPROMELLOSE OF DIFFERENT VISCOSITY DEGREE AND GLYCERYL DIBEHENATE.

    PubMed

    Mužíková, Jitka; Holubová, Katerina; Komersová, Alena; Lochar, Václav

    2016-01-01

    Studies are described on the compressibility of directly compressible tableting materials containing two viscosity types of hypromellose in two concentrations and tableting materials containing additional glyceryl dibehenate, also in two concentrations. Compressibility is evaluated by means of the energy profile of the compression process and determination of tensile strength of tablets. Dissolution test examines the rate of release of the active ingredient from matrix tablets, which is subsequently evaluated mathematically. Increased concentrations of both hypromelloses and an addition of glyceryl dibehenate into tablets with both types of hypromellose improved compressibility. The rate of drug release was decreased with increasing viscosity degree of hypromellose and its increasing concentration. An addition of glyceryl dibehenate exerted the same influence on release as increased concentrations of the pertinent hypromellose.

  1. 21 CFR 178.3505 - Glyceryl tri-(12-acetoxy-stearate).

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Glyceryl tri-(12-acetoxy-stearate). 178.3505 Section 178.3505 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) INDIRECT FOOD ADDITIVES: ADJUVANTS, PRODUCTION AIDS, AND SANITIZERS Certain Adjuvants...

  2. Water quantitatively induces the mucoadhesion of liquid crystalline phases of glyceryl monooleate.

    PubMed

    Lee, J; Young, S A; Kellaway, I W

    2001-05-01

    The possible role of water in the mucoadhesion phenomenon exhibited by the liquid crystalline phases of glyceryl monooleate was investigated using an in-vitro tensile strength technique. The mucoadhesion of the liquid crystalline phases of glyceryl monooleate was found to occur following uptake of water. The mucoadhesive force of the cubic phase was consistent since it is not capable of taking up additional water. An increase in pre-load period greatly facilitated the mucoadhesion of glyceryl monooleate (0% w/w initial water content), suggesting that the mucoadhesion is dependent upon the extent of the dehydration of the substrate. A good linear relationship between initial water content of the liquid crystalline phases and mucoadhesive force led to the conclusion that the mucoadhesive force increased with decreasing initial water concentration. Rheological properties of the liquid crystalline phases were also studied to allow a correlation between physical changes and mucoadhesion of the liquid crystalline phases, revealing that higher water concentrations in the liquid crystalline phases led to a more ordered structure that showed less mucoadhesion. The results of this study indicated that the mucoadhesive force of the liquid crystalline phases of glyceryl monooleate is determined by the capability to take up water from a water-rich environment. It may, therefore, be advantageous to use the lamellar phase as a buccal drug carrier as opposed to the relatively less mucoadhesive cubic phase.

  3. Final report on the safety assessment of trilaurin, triarachidin, tribehenin, tricaprin, tricaprylin, trierucin, triheptanoin, triheptylundecanoin, triisononanoin, triisopalmitin, triisostearin, trilinolein, trimyristin, trioctanoin, triolein, tripalmitin, tripalmitolein, triricinolein, tristearin, triundecanoin, glyceryl triacetyl hydroxystearate, glyceryl triacetyl ricinoleate, and glyceryl stearate diacetate.

    PubMed

    Johnson, W

    2001-01-01

    Triesters of glycerin and aliphatic acids, known generically as glyceryl triesters and specifically as Trilaurin, etc., are used in cosmetic products as occlusive skin-conditioning agents and/or nonaqueous viscosity-increasing agents. Hundreds of glyceryl triesters are used in a wide variety of cosmetic products at concentrations ranging from a few tenths of a percent to 46%. Glyceryl triesters are also known as triglycerides; ingested triglycerides are metabolized to monoglycerides, free fatty acids, and glycerol, all of which are absorbed in the intestinal mucosa and undergo further metabolism. Dermal absorption of Triolein in mice was nil; the oil remained at the application site. Only slight absorption was seen in guinea pig skin. Tricaprylin and other glyceryl triesters have been shown to increase the skin penetration of drugs. Little or no acute, subchronic, or chronic oral toxicity was seen in animal studies unless levels approached a significant percentage of caloric intake. Subcutaneous injections of Tricaprylin in rats over a period of 5 weeks caused a granulomatous reaction characterized by oil deposits surrounded by macrophages. Dermal application was not associated with significant irritation in rabbit skin. Ocular exposures were, at most, mildly irritating to rabbit eyes. No evidence of sensitization or photosensitization was seen in a guinea pig maximization test. Most of the genotoxicity test systems were negative. Tricaprylin, Trioctanoin, and Triolein have historically been used as vehicles in carcinogenicity testing of other chemicals. In one study, subcutaneous injection of Tricaprylin in newborn mice produced more tumors in lymphoid tissue than were seen in untreated animals, whereas neither subcutaneous or intraperitoneal injection in 4- to 6-week-old female mice produced any tumors in another study. Trioctanoin injected subcutaneously in hamsters produced no tumors. Trioctanoin injected intraperitoneally in pregnant rats was associated with

  4. Fabrication of an octadecylated silica monolith inside a glass microchip for protein enrichment.

    PubMed

    Alzahrani, Eman; Welham, Kevin

    2012-10-21

    Silica-based monolithic materials have shown great promise for use as sorbent materials due to their large surface area and bimodal pore size distribution. In this paper, a new process for the fabrication of a silica-based monolith inside a glass microchip and its modification with octadecylsilyl ligands was successfully developed for use in the microchip-based solid phase extraction of proteins. Monolithic porous silica without cracks was prepared by a sol-gel process, followed by placement of the monolithic silica disk inside the extraction chamber in the base plate of the microchip. The two plates of the glass microchip were then thermally bonded at 575 °C for 3 hours. The silica-based monolith was not affected by the thermal bonding of the two plates of the microchip. This process completely avoids the problem of shrinkage in the silica skeleton during preparation. The monolithic silica disk inside the glass microchip was subsequently modified with octadecylsilyl (C(18)) moieties for increased protein binding capacity. The performance of the microchip was evaluated using the extraction of six proteins varying in molecular weight and isoelectric point, namely insulin, cytochrome C, lysozyme, myoglobin, β-lactoglobulin, and hemoglobin at a concentration of 60 μM. The standard protein was mixed with a double concentration of the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate (CHAPS). The results show that the octadecylated silica monolith was permeable, has the ability to remove impurities, and achieved a high extraction recovery of the proteins (94.8-99.7%) compared with conventional octadecylated silica particles (48.3-91.3%). The chip-to-chip reproducibility was assessed by calculating the relative standard deviations (RSDs) for the six proteins during extraction. The intra-batch and inter-batch RSDs were in the range of 2.0-4.5% and 2.9-6.4%, respectively. This new microfluidic device for protein extraction may find an application in

  5. Separation and preconcentration of cadmium ions using octadecyl silica membrane disks modified by methyltrioctylammonium chloride.

    PubMed

    Haji Shabani, Ali Mohammad; Dadfarnia, Shayesteh; Motavaselian, Fatemeh; Ahmadi, Seyyed Hamid

    2009-02-15

    A simple and selective method for the determination of cadmium in water samples by FAAS after solid phase extraction has been developed. The method is based on the sorption of cadmium as CdI(4)(2-) on octadecyl silica membrane disks modified by cationic surfactant of methyltrioctylammonium chloride in the pH range of 1-8. The sorbed cadmium is then eluted with 10ml of 1moll(-1) nitric acid in ethanol and is measured by flame atomic absorption spectrometry. The influence of flow rates of eluent and sample solution, iodide concentration and amount of surfactant in retention and elution of cadmium from disks was also investigated. A preconcentration factor of 100 was achieved by passing 1000ml of sample through the membrane disk. The limit of detection (LOD) of cadmium was found to be 0.014ngml(-1). Precision at 2.5mugl(-1) was 1.2% (n=8). The method was successfully applied to the determination of cadmium in some natural water samples. The accuracy was assessed through recovery experiment, independent analysis by graphite furnace atomic absorption spectrometry, and analysis of certified reference waters.

  6. Targeted therapy of colorectal neoplasia with rapamycin in peptide-labeled pegylated octadecyl lithocholate micelles.

    PubMed

    Khondee, Supang; Rabinsky, Emily F; Owens, Scott R; Joshi, Bishnu P; Qiu, Zhen; Duan, Xiyu; Zhao, Lili; Wang, Thomas D

    2015-02-10

    Many powerful drugs have limited clinical utility because of poor water solubility and high systemic toxicity. Here, we formulated a targeted nanomedicine, rapamycin encapsulated in pegylated octadecyl lithocholate micelles labeled with a new ligand for colorectal neoplasia, LTTHYKL peptide. CPC;Apc mice that spontaneously develop colonic adenomas were treated with free rapamycin, plain rapamycin micelles, and peptide-labeled rapamycin micelles via intraperitoneal injection for 35days. Endoscopy was performed to monitor adenoma regression in vivo. We observed complete adenoma regression at the end of therapy. The mean regression rate for peptide-labeled rapamycin micelles was significantly greater than that for plain rapamycin micelles, P<0.01. On immunohistochemistry, we observed a significant reduction in phospho-S6 but not β-catenin expression and reduced tumor cell proliferation, suggesting greater inhibition of downstream mTOR signaling. We observed significantly reduced renal toxicity for peptide-labeled rapamycin micelles compared to that of free drug, and no other toxicities were found on chemistries. Together, this unique targeted micelle represents a potential therapeutic for colorectal neoplasia with comparable therapeutic efficacy to rapamycin free drug and significantly less systemic toxicity.

  7. Biocompatible microemulsions for fabrication of glyceryl monostearate solid lipid nanoparticles (SLN) of tretinoin.

    PubMed

    Shah, Kumar A; Joshi, Medha D; Patravale, Vandana B

    2009-08-01

    The objective of the present investigation was to fabricate glyceryl monostearate SLN by employing a biocompatible microemulsion as a template. Biocompatible excipients such as Tween 20 (as a surfactant) and Transcutol P (a cosourfactant) (at different K(m) ratios) were selected for the fabrication of microemulsions. Pseudo-ternary phase diagrams were plotted to identify the area of the microemulsion existence. Glyceryl monostearate SLN were fabricated by dispersing the microemulsion (maintained at 65 degrees C) into cold water (maintained at 2-3 degrees C). The particle size of the SLN was determined by photon correlation spectroscopy. Tretinoin, a lipophilic anti-acne agent was incorporated into SLN as a model drug. The encapsulation efficiency of tretinoin in the SLN was determined by using Nanosep ultrafilteration device at different lipid loads viz. 1%, 1.5% and 2%. Glyceryl monostearate SLN fabricated from biocompatible microemulsion template exhibited average particle size of 175 nm and polydispersity index of 0.833. Tretinoin could be successfully incorporated into SLN and the encapsulation efficiency ranged from 37-48% at different lipid loads.

  8. Preparation and chromatographic evaluation of new branch-type diamide-embedded octadecyl stationary phase with enhanced shape selectivity.

    PubMed

    Zhang, Mingliang; Chen, Jia; Mallik, Abul K; Qiu, Hongdeng; Jiang, Shengxiang; Ihara, Hirotaka

    2014-06-23

    A novel branch-type diamide-embedded octadecyl stationary phase was prepared by facile amidation. The preparation of this new phase involves the synthesis of new bifunctional silane ligand and surface modification of spherical silica via anchoring of silane coupling agent. The obtained diamide-embedded octadecyl stationary phase demonstrated excellent hydrophobic selectivity, as well as enhanced shape and planarity selectivity in comparison to commercial polymeric and monomeric C18 phases, respectively, as revealed by the systematic investigation into its liquid chromatographic retention of isomeric polycyclic aromatic hydrocarbons. The applicability of this new stationary phase was further testified by the effective separation of isomeric compounds belong to different chemical classes, including chain isomers of alkylbenzenes, and positional isomers of substituted aromatics. An in-depth analysis of the separation mechanisms other than molecular shape recognition involved in the new stationary phase was performed using a linear solvation energy relationships model and compared with its monoamide and pure C18 counterparts correspondingly. The performance of the new stationary phase in quantitative analysis of phenols from real-world samples was also evaluated.

  9. Application of the Flory-Huggins theory to the solubility of solids in glyceryl trioleate

    USGS Publications Warehouse

    Chiou, Cary T.; Manes, Milton

    1986-01-01

    The conventional thermodynamic deviation for ideal solid–liquid solubilities is modified by substituting the Flory–Huggins model for Raoult's law. A comparison of published data for eleven solides in glyceryl trioleate with the predictions of the conventional and modified equations shows that the significantly higher athermal solubilities from the modified equation are in much better agreement with the experimental data. This suggests that discrepancies between the data and the predictions of the conventional model for ideal systems result from the inappropriate use of Raoult's law for systems with significant solute–solvent size disparity rather than from specific interactions.

  10. Comparative study of glyceryl trinitrate ointment versus surgical management of chronic anal fissure.

    PubMed

    Tauro, Leo Francis; Shindhe, Vittal V; Aithala, P Sathyamoorthy; Martis, John J S; Shenoy, H Divakar

    2011-08-01

    Chronic Anal Fissure (CAF) is common perineal condition and well-known painful entity. Standard surgical treatment even though available, may require long hospital stay and sometimes have worrying complications like anal incontinence. So non-surgical treatment, Glyceryl Trinitrate has been shown to be an effective for chronic anal fissure. It decreases anal tone and ultimately heals the anal fissure. The present study is the attempt to know the efficacy of 0.2% Glyceryl Trinitrate ointment in the treatment of chronic anal fissure and to compare the effectiveness of 0.2% Glyceryl Trinitrate ointment (GTN) versus fissurectomy with lateral internal sphincterotomy (LIS) and fissurectomy with posterior internal sphincterotomy (PIS) in the management of chronic anal fissure. This is a prospective comparative study of management of chronic anal fissure done in our hospital during the period of one and half year from October 2005 to March 2007. Thirty patients treated with 0.2% Glyceryl Trinitrate ointment and 30 patients treated with fissurectomy and lateral internal sphincterotomy and 30 patients treated with posterior internal sphincterotomy, for chronic anal fissure were selected for study. A single brand of 0.2% Glyceryl Trinitrate ointment (Nitrogesic) used for trial arm. Dose of administration was 1.5 cm to 2 cm in the anal canal with device provided by manufacturers of the proprietary preparation and applied twice a daily for 12 weeks. Patients were followed up for 12 weeks and thereafter evaluated for relief of symptoms in all three groups. Observations were recorded at 2 weeks; 6 weeks and 12 weeks of follow up period, regarding symptoms like pain and bleeding during defecation, healing of CAF and also for side effects like headache in GTN group and flatus, fecal incontinence in surgical groups. Data collected in proforma and analyzed. Study revealed CAF was more in male 59 patients (66%) than the female 31 patients (34%), the ratio being 1: 0.52. The

  11. Parasite impairment by targeting Plasmodium-infected RBCs using glyceryl-dilaurate nanostructured lipid carriers.

    PubMed

    Jain, Soniya A; Basu, Himanish; Prabhu, Priyanka S; Soni, Umangi; Joshi, Medha D; Mathur, Deepak; Patravale, Vandana B; Pathak, Sulabha; Sharma, Shobhona

    2014-08-01

    Antimalarial therapy is a major contributor to declining malaria morbidity and mortality. However, the high toxicity and low bioavailability of current antimalarials and emerging drug resistance necessitates drug-delivery research. We have previously developed glyceryl-dilaurate nanolipid carriers (GDL-NLCs) for antimalarial drug delivery. Here, we show evidence that GDL-NLCs themselves selectively target Plasmodium-infected red blood cells (iRBCs), and cause severe parasite impairment. The glyceryl-dilaurate lipid-moiety was important in the targeting. GDL-NLCs localized to the parasite mitochondrion and uptake led to mitochondrial-membrane polarization and Ca(2+) ion accumulation, ROS release, and stage-specific iRBC lysis. GDL-NLC treatment also resulted in externalization of iRBC-membrane phosphatidylserine and enhanced iRBC clearance by macrophages. GDL-NLC uptake disrupted the parasite-induced tubulovesicular network, which is vital for nutrient import by the parasite. Laser optical trap studies revealed that GDL-NLCs also restored iRBC flexibility. Such restoration of iRBC flexibility may help mitigate the vasculature clogging that can lead to cerebral malaria. We demonstrate the suitability of GDL-NLCs for intravenous delivery of antimalarial combinations artemether-clindamycin and artemether-lumefantrine in the murine model. Complete parasite clearance was achieved at 5-20% of the therapeutic dose of these combinations. Thus, this nanostructured lipid formulation can solubilize lipophilic drugs, selectively target and impair the parasite-infected red cell, and therefore constitutes a potent delivery vehicle for antimalarials.

  12. A new sunscreen of the cinnamate class: synthesis and enzymatic hydrolysis evaluation of glyceryl esters of p-methoxycinnamic acid.

    PubMed

    de Freitas, Zaida Maria Faria; dos Santos, Elisabete Pereira; da Rocha, João Ferreira; Dellamora-Ortiz, Gisela Maria; Gonçalves, José Carlos Saraiva

    2005-05-01

    Glyceryl esters of p-methoxycinnamic acid, 1,3-dipalmitoyl-2-p-methoxycinnamoyl-1,2,3-propanetriol and 1,3-dioctanoyl-2-p-methoxycinnamoyl-1,2,3-propanetriol were synthesised in an attempt to increase substantivity and decrease eventual undesirable effects of sunscreens of this class. To assess if the glyceryl esters could present a higher stability towards hydrolysis by lipases in the stratum corneum, hydrolysis rates were determined in vitro using a commercial fungal lipase from Rhizomucor miehei. Results presented herein show that the glyceryl esters have similar lambda(max) and epsilon values to sunscreens of the cinnamate class. The ester 1,3-dipalmitoyl-2-p-methoxycinnamoyl-1,2,3-propanetriol presented a 2.8 times lower hydrolysis rate by lipase, in vitro, than the commercial sunscreen 2-ethylhexyl-p-methoxycinnamate (alkyl ester). This finding suggests that this triacylglycerol can possibly have a longer retention time in the skin and consequently promote a more intense and effective antisolar action than the commercial sunscreen.

  13. Improved preservation of the rat heart with celsior solution supplemented with cariporide plus glyceryl trinitrate.

    PubMed

    Gao, Ling; Hicks, Mark; MacDonald, Peter S

    2005-08-01

    Our aim was to investigate whether the addition of glyceryl trinitrate (GTN), a source of nitric oxide, and/or cariporide, a Na/H exchange inhibitor, to a commercial preservation solution (Celsior) improved and extended cardiac preservation. After baseline indices of cardiac function (aortic flow, coronary flow, heart rate, cardiac output) were measured in an isolated working rat heart model, hearts were arrested and stored at 2-3 degrees C for 6 or 10 h in Celsior solution alone, Celsior supplemented with either 0.1 mg/mL GTN or 10 microM cariporide or both. After storage, functional measurements were repeated and recovery of each parameter was expressed as a percentage of its pre-storage baseline. After 6 h storage, recovery of cardiac function was significantly better in hearts stored in GTN- or cariporide-supplemented Celsior solution compared with Celsior solution alone. The beneficial effect of GTN was significantly abrogated in hearts perfused with glibenclamide prior to storage. Significant recovery of cardiac function after 10 h storage was only observed in hearts stored in Celsior solution supplemented with both GTN and cariporide. Combined supplementation with GTN and cariporide extends the safe period of storage of the rat heart and may be a useful approach to enhancing preservation of the donor heart.

  14. RNA Sequencing of Trigeminal Ganglia in Rattus Norvegicus after Glyceryl Trinitrate Infusion with Relevance to Migraine

    PubMed Central

    Hougaard Pedersen, Sara; Maretty, Lasse; Ramachandran, Roshni; Sibbesen, Jonas Andreas; Yakimov, Victor; Elgaard-Christensen, Rikke; Hansen, Thomas Folkmann; Krogh, Anders; Olesen, Jes; Jansen-Olesen, Inger

    2016-01-01

    Introduction Infusion of glyceryl trinitrate (GTN), a donor of nitric oxide, induces immediate headache in humans that in migraineurs is followed by a delayed migraine attack. In order to achieve increased knowledge of mechanisms activated during GTN-infusion this present study aims to investigate transcriptional responses to GTN-infusion in the rat trigeminal ganglia. Methods Rats were infused with GTN or vehicle and trigeminal ganglia were isolated either 30 or 90 minutes post infusion. RNA sequencing was used to investigate transcriptomic changes in response to the treatment. Furthermore, we developed a novel method for Gene Set Analysis Of Variance (GSANOVA) to identify gene sets associated with transcriptional changes across time. Results 15 genes displayed significant changes in transcription levels in response to GTN-infusion. Ten of these genes showed either sustained up- or down-regulation in the 90-minute period after infusion. The GSANOVA analysis demonstrate enrichment of pathways pointing towards an increase in immune response, signal transduction, and neuroplasticity in response to GTN-infusion. Future functional in-depth studies of these mechanisms are expected to increase our understanding of migraine pathogenesis. PMID:27213950

  15. Silymarin glyceryl monooleate/poloxamer 407 liquid crystalline matrices: physical characterization and enhanced oral bioavailability.

    PubMed

    Lian, Ruyue; Lu, Yi; Qi, Jianping; Tan, Yanan; Niu, Mengmeng; Guan, Peipei; Hu, Fuqiang; Wu, Wei

    2011-12-01

    Silymarin, a mixture of flavonolignans extracted from the seeds of milk thistle, is used clinically as a hepatoprotector to treat liver injuries and chronic hepatitis. However, its therapeutic effect is compromised by its poor oral bioavailability due to the poor solubility and low permeability across intestinal epithelia. The main purpose of this study was to prepare silymarin glyceryl monooleate/poloxamer 407 liquid crystalline matrices (GMO/P407 LCM) to improve the oral bioavailability of silymarin. GMO/P407 LCMs were prepared by a melting/congealing method. The isotropic phenomenon observed under polarized light microscope confirmed the liquid crystalline structure at the junction of LCM and water. Both differential scanning calorimetry and X-ray diffraction analysis confirmed disappearance of silymarin crystallinity after incorporation into the LCMs. In vitro release of silymarin from LCMs was limited, whereas LCMs were readily degraded by lipase and released silymarin quickly and completely. Pharmacokinetic study in beagle dogs showed significantly increased peak concentration for silymarin GMO/P407 LCM, and, most importantly, a 3.46-fold increase in oral bioavailability as compared with Legalon®, a commercial silymarin formulation.

  16. Glyceryl Trinitrate Ointment Did Not Reduce Pain After Stapled Hemorrhoidectomy: A Randomized Controlled Trial

    PubMed Central

    Cross, Trent; Bartlett, Lynne; Mushaya, Chrispen; Ashour, Mohamed; Ho, Yik-Hong

    2012-01-01

    Medications, including topical 0.2% glyceryl trinitrate (GTN), can reduce anal spasm and pain after excisional hemorrhoidectomy. GTN after stapled hemorrhoidopexy was compared with routine postoperative management. Patients with symptomatic grade 3/4 hemorrhoids were recruited. After stapled hemorrhoidopexy, residual perianal skin tags were excised as appropriate. Those requiring double purse-string mucosectomy were excluded. Postoperative pain, pain duration, and complications were assessed. One hundred ten patients (74 men; mean age 50.6 years) were enrolled in the control group and 100 patients (57 men; mean age 49.8 years) in the GTN group. Maximum pain was higher in the GTN group (P  =  0.015). There were no differences between the two groups in residual perianal skin tags requiring excision, postoperative complications, recurrence rates, follow-up period, average pain, duration of pain, or satisfaction scores. Sixteen GTN patients were noncompliant due to side effects. None had persistent perianal skin tags. GTN did not reduce postoperative pain after stapled hemorrhoidectomy. PMID:23102076

  17. Development and evaluation of liquid embolic agents based on liquid crystalline material of glyceryl monooleate.

    PubMed

    Du, Ling-Ran; Lu, Xiao-Jing; Guan, Hai-Tao; Yang, Yong-Jie; Gu, Meng-Jie; Zheng, Zhuo-Zhao; Lv, Tian-Shi; Yan, Zi-Guang; Song, Li; Zou, Ying-Hua; Fu, Nai-Qi; Qi, Xian-Rong; Fan, Tian-Yuan

    2014-08-25

    New type of liquid embolic agents based on a liquid crystalline material of glyceryl monooleate (GMO) was developed and evaluated in this study. Ternary phase diagram of GMO, water and ethanol was constructed and three isotropic liquids (ILs, GMO:ethanol:water=49:21:30, 60:20:20 and 72:18:10 (w/w/w)) were selected as potential liquid embolic agents, which could spontaneously form viscous gel cast when contacting with water or physiological fluid. The ILs exhibited excellent microcatheter deliverability due to low viscosity, and were proved to successfully block the saline flow when performed in a device to simulate embolization in vitro. The ILs also showed good cytocompatibility on L929 mouse fibroblast cell line. The embolization of ILs to rabbit kidneys was performed successfully under monitoring of digital subtraction angiography (DSA), and embolic degree was affected by the initial formulation composition and used volume. At 5th week after embolization, DSA and computed tomography (CT) confirmed the renal arteries embolized with IL did not recanalize in follow-up period, and an obvious atrophy of the embolized kidney was observed. Therefore, the GMO-based liquid embolic agents showed feasible and effective to embolize, and potential use in clinical interventional embolization therapy.

  18. Liquid crystalline phases and their dispersions in aqueous mixtures of glycerol monooleate and glyceryl monooleyl ether.

    PubMed

    Popescu, Georgeta; Barauskas, Justas; Nylander, Tommy; Tiberg, Fredrik

    2007-01-16

    The aqueous phase behavior of mixtures of 1-glycerol monooleate (GMO) and its ether analogue, 1-glyceryl monooleyl ether (GME) has been investigated by a combination of polarized microscopy, X-ray diffraction, and NMR techniques. Three phase diagrams of the ternary GMO/GME/water system have been constructed at 25, 40, and 55 degrees C. The results demonstrate that the increasing amount of GME favors the formation of the reversed phases, evidenced by the transformation of the lamellar and bicontinuous cubic liquid crystalline phases of the binary GMO/water system into reversed micellar or reversed hexagonal phases. For a particular liquid crystalline phase, increasing the GME content has no effect on the structural characteristics and hydration properties, thus suggesting ideal mixing with GMO. Investigations of dispersed nanoparticle samples using shear and a polymeric stabilizer, Pluronic F127, show the possibility of forming two different kinds of bicontinuous cubic phase nanoparticles by simply changing the GMO/GME ratio. Also NMR self-diffusion measurements confirm that the block copolymer, Pluronic F127, used to facilitate dispersion formation, is associated with nanoparticles and provides steric stabilization.

  19. Preparation of multiparticulate vaginal tablet using glyceryl monooleate for sustained progesterone delivery.

    PubMed

    Biradar, Shailesh V; Dhumal, Ravindra S; Shah, Manish H; Paradkar, Anant R; Yamamura, Shigeo

    2009-01-01

    Most of the sustained release vaginal formulations are in the form of bioadhesive gels and tablets. Though proved efficient, their presence in the vagina for a longer time as a bulk produces discomfort and interference with body functioning including sexual activities. Hence, they lack complete patient compliance. In this study, multiparticulate vaginal tablets were prepared by utilizing progesterone (PRO) loaded dry powder precursor of cubic phase (DPPCP) of glyceryl monooleate (GMO). DPPCP were obtained by spray drying GMO with magnesium trisilicate (MTS) and have presented PRO sustained release in simulated vaginal fluid (SVF) for 14 hours. The effect of hydrophilic and hydrophobic tableting excipients on compression, phase, bioadhesion and drug release properties of prepared tablets was evaluated. The effervescent hydrophilic tablet (EHT) prepared with hydrophilic excipients showed rapid disintegration but, diminished sustaining ability owing to transformation into lamellar phase whereas the multiparticulate hydrophobic tablet (MHT) obtained from hydrophobic excipients presented both rapid disintegration and sustained release in SVF by virtue of cubic phase retention. During bioadhesivity testing, fast disintegration of MHT with formation of uniform and viscous bioadhesive layer on cow mucosa was observed even with a small volume of SVF. As MHT may not produce discomfort and interference, it will be preferred over bioadhesive gel or tablet.

  20. Steady-state maternal and fetal plasma concentrations of glyceryl trinitrate (GTN) in the preterm sheep.

    PubMed

    Bustard, Mark A; Farley, Anne E; Bennett, Brian M; Smith, Graeme N

    2003-09-01

    The administration of glyceryl trinitrate (GTN; nitroglycerin) is increasing during preterm pregnancies, yet its disposition and, importantly, the extent of fetal exposure remain to be elucidated. When used as a tocolytic (pharmacological agent that stops uterine contractions), it is administered transdermally (24-48 h). Here, we quantified the maternal and fetal steady-state plasma concentrations of maternal intravenous GTN in preterm sheep and continuously monitored maternal and fetal vascular parameters to observe possible dose-dependent vascular effects. Preterm (120 days gestation) pregnant sheep (n = 6) were instrumented with maternal femoral arterial (MA) and venous (MV) and fetal femoral arterial (FA) and umbilical venous (UV) polyethylene blood-sampling catheters. During maternal GTN infusion (3.0 micro g.kg-1.min-1, 60-min duration) the steady-state GTN concentrations ([GTN]) were as follows: MA, 98.6 +/- 9.0 nM; UV, 17.4 +/- 7.6 nM; and FA, <5 nM. There were no changes in maternal and fetal mean arterial pressure and heart rate or in uterine activity. Overall, the steady-state [GTN] was established by 5 min, and the UV/MA ratio of [GTN] was 0.18. The FA [GTN] (<5 nM) indicates that the fetus cleared essentially all GTN in the UV, and the maternal and fetal heart rate and mean arterial pressure appear to be independent of maternal GTN infusion.

  1. Computational and Biological Evaluation of N-octadecyl-N′-propylsulfamide, a Selective PPARα Agonist Structurally Related to N-acylethanolamines

    PubMed Central

    Serrano, Antonia; Cano, Carolina; Suardíaz, Margarita; Decara, Juan; Suarez, Juan; de Fonseca, Fernando Rodríguez; Macías-González, Manuel

    2014-01-01

    To further understand the pharmacological properties of N-oleoylethanolamine (OEA), a naturally occurring lipid that activates peroxisome proliferator-activated receptor alpha (PPARα), we designed sulfamoyl analogs based on its structure. Among the compounds tested, N-octadecyl-N′-propylsulfamide (CC7) was selected for functional comparison with OEA. The performed studies include the following computational and biological approaches: 1) molecular docking analyses; 2) molecular biology studies with PPARα; 3) pharmacological studies on feeding behavior and visceral analgesia. For the docking studies, we compared OEA and CC7 data with crystallization data obtained with the reference PPARα agonist GW409544. OEA and CC7 interacted with the ligand-binding domain of PPARα in a similar manner to GW409544. Both compounds produced similar transcriptional activation by in vitro assays, including the GST pull-down assay and reporter gene analysis. In addition, CC7 and OEA induced the mRNA expression of CPT1a in HpeG2 cells through PPARα and the induction was avoided with PPARα-specific siRNA. In vivo studies in rats showed that OEA and CC7 had anorectic and antiobesity activity and induced both lipopenia and decreases in hepatic fat content. However, different effects were observed when measuring visceral pain; OEA produced visceral analgesia whereas CC7 showed no effects. These results suggest that OEA activity on the PPARα receptor (e.g., lipid metabolism and feeding behavior) may be dissociated from other actions at alternative targets (e.g., pain) because other non cannabimimetic ligands that interact with PPARα, such as CC7, do not reproduce the full spectrum of the pharmacological activity of OEA. These results provide new opportunities for the development of specific PPARα-activating drugs focused on sulfamide derivatives with a long alkyl chain for the treatment of metabolic dysfunction. PMID:24651609

  2. Computational and biological evaluation of N-octadecyl-N'-propylsulfamide, a selective PPARα agonist structurally related to N-acylethanolamines.

    PubMed

    Moreno-Santos, Inmaculada; Pavón, Francisco Javier; Romero-Cuevas, Miguel; Serrano, Antonia; Cano, Carolina; Suardíaz, Margarita; Decara, Juan; Suarez, Juan; de Fonseca, Fernando Rodríguez; Macías-González, Manuel

    2014-01-01

    To further understand the pharmacological properties of N-oleoylethanolamine (OEA), a naturally occurring lipid that activates peroxisome proliferator-activated receptor alpha (PPARα), we designed sulfamoyl analogs based on its structure. Among the compounds tested, N-octadecyl-N'-propylsulfamide (CC7) was selected for functional comparison with OEA. The performed studies include the following computational and biological approaches: 1) molecular docking analyses; 2) molecular biology studies with PPARα; 3) pharmacological studies on feeding behavior and visceral analgesia. For the docking studies, we compared OEA and CC7 data with crystallization data obtained with the reference PPARα agonist GW409544. OEA and CC7 interacted with the ligand-binding domain of PPARα in a similar manner to GW409544. Both compounds produced similar transcriptional activation by in vitro assays, including the GST pull-down assay and reporter gene analysis. In addition, CC7 and OEA induced the mRNA expression of CPT1a in HpeG2 cells through PPARα and the induction was avoided with PPARα-specific siRNA. In vivo studies in rats showed that OEA and CC7 had anorectic and antiobesity activity and induced both lipopenia and decreases in hepatic fat content. However, different effects were observed when measuring visceral pain; OEA produced visceral analgesia whereas CC7 showed no effects. These results suggest that OEA activity on the PPARα receptor (e.g., lipid metabolism and feeding behavior) may be dissociated from other actions at alternative targets (e.g., pain) because other non cannabimimetic ligands that interact with PPARα, such as CC7, do not reproduce the full spectrum of the pharmacological activity of OEA. These results provide new opportunities for the development of specific PPARα-activating drugs focused on sulfamide derivatives with a long alkyl chain for the treatment of metabolic dysfunction.

  3. Spray dried glyceryl monooleate-magnesium trisilicate dry powder as cubic phase precursor.

    PubMed

    Shah, Manish H; Biradar, Shailesh V; Paradkar, Anant R

    2006-10-12

    Glyceryl monooleate (GMO) is a polar amphiphilic lipid, which forms different sequential lyotropic liquid crystals upon hydration. GMO has been utilized for various delivery systems and routes of administrations. Owing to sticky and waxy nature of GMO, preparation of oral solid dosage form utilizing GMO is still a challenge for pharmaceutical researchers. Therefore, the objective of the present work was to fabricate dry powder precursors using GMO, which upon hydration in situ forms cubic phase and can be wisely used for fabrication of oral solid dosage forms. In addition to this, dry powder precursor was evaluated for drug loading, in vitro release behavior and in vivo performance of model drug diclofenac sodium (DiNa). The dry powder precursor was obtained by spray-drying GMO with DiNa using magnesium trisilicate (MTS) as adsorbent. The percent drug entrapment of various batches of powder precursor was in the range of 84-93% indicating high content uniformity. SEM and image analysis showed that as the amount of MTS in powder precursor was increased, the particle size decreased. Furthermore, the viscosity of powder precursor was function of amount of MTS. The rate of water uptake of powder precursor was higher due to uniform layer of GMO on the MTS surface, which led to faster transformation of lamellar phase into cubic phase. The polarizing light microscopy confirmed that cubic phase was formed upon hydration of powder precursor. The drug released from powder precursor was initially governed by the cubic phase formed and in later stage it depends upon dynamic swelling behavior of hexagonally packed cylindrical aggregates. The drug loaded powder precursor was found to have more effective and prolonged anti-inflammatory and analgesic activity as compared to pure drug. Thus the dry powder precursor of cubic phase was prepared in which drug release was entirely governed by the mesophases formed.

  4. Investigation of oxidant stress and vasodepression to glyceryl trinitrate in the obese Zucker rat in vivo

    PubMed Central

    Laight, David W; Kengatharan, K M; Gopaul, Nitin K; Änggård, Erik E; Carrier, Martin J

    1998-01-01

    We examined the relationship between oxidant stress and the vasodepressor activity of glyceryl trinitrate (GTN) in vivo, including rapid GTN tolerance development, in 13-week old obese and age-matched lean Zucker rats which had been maintained for 4 weeks on either control diet or diets enriched with the lipophilic, chain-breaking antioxidants vitamin E (0.5% w w−1) or probucol (0.5% w w−1) or the superoxide anion scavenger tiron (1% w v−1 in drinking water).The basal plasma level of the isoprostane 8-epi-PGF2α, an in vivo marker of lipid peroxidation, was elevated by approximately 5 fold in the obese Zucker rat and markedly reduced by dietary lipophilic antioxidants and depressed by dietary tiron.Vasodepression to bolus does GTN (0.1–100 μg kg−1 i.v.), but not endothelium-dependent vasodepression to bolus dose acetylcholine (ACh, 0.02–2.0 μg kg−1 i.v.), was impaired in obese animals and completely restored by dietary antioxidants.Nitrate tolerance developed in vivo during a 1 h infusion of GTN (40 μg kg−1 min−1 i.v.) appeared more severe in obese animals. However, rapid nitrate tolerance was not affected by dietary antioxidants in either the obese or lean Zucker rat.We therefore provide evidence that elevated oxidant stress in the obese Zucker rat is associated with an impairment in nitrate vasodepressor activity. However, our data are not consistent with either a role for oxidant stress in rapid nitrate tolerance development in the anaesthetized Zucker rat or the aggravation of this tolerance by pre-existing oxidant stress. PMID:9831930

  5. Continuous twin screw melt granulation of glyceryl behenate: Development of controlled release tramadol hydrochloride tablets for improved safety.

    PubMed

    Keen, Justin M; Foley, Connor J; Hughey, Justin R; Bennett, Ryan C; Jannin, Vincent; Rosiaux, Yvonne; Marchaud, Delphine; McGinity, James W

    2015-06-20

    Interest in granulation processes using twin screw extrusion machines is rapidly growing. The primary objectives of this study were to develop a continuous granulation process for direct production of granules using this technique with glyceryl behenate as a binder, evaluate the properties of the resulting granules and develop controlled release tablets containing tramadol HCl. In addition, the granulation mechanism was probed and the polymorphic form of the lipid and drug release rate were evaluated on stability. Granules were prepared using a Leistritz NANO16 twin screw extruder operated without a constricting die. The solid state of the granules were characterized by differential scanning calorimetry and X-ray diffraction. Formulated tablets were studied in 0.1N HCl containing 0-40% ethanol to investigate propensity for alcohol induced dose dumping. The extrusion barrel temperature profile and feed rate were determined to be the primary factors influencing the particle size distribution. Granules were formed by a combination immersion/distribution mechanism, did not require subsequent milling, and were observed to contain desirable polymorphic forms of glyceryl behenate. Drug release from tablets was complete and controlled over 16 h and the tablets were determined to be resistant to alcohol induced dose dumping. The drug release rate from the tablets was found to be stable at 40°C and 75% relative humidity for the duration of a 3 month study.

  6. Fluorescent turn-on detection and assay of water based on 4-(2-dimethylaminoethyloxy)-N-octadecyl-1,8-naphthalimide with aggregation-induced emission enhancement

    NASA Astrophysics Data System (ADS)

    Sun, Yang; Liang, Xuhua; Wei, Song; Fan, Jun; Yang, Xiaohui

    2012-11-01

    The photophysical properties of 4-(2-dimethylaminoethyloxy)-N-octadecyl-1,8-naphthalimide (DON) consisting of donor and acceptor units were investigated in different solutions. Changing from a non-polar to a polar solvent increased the solvent interaction and both the excitation and emission spectra were shifted to longer wavelength and intensity decreased through taking advantage of twisted intramolecular charge transfer (TICT). Density functional theory (DFT) calculations and spectral analyses revealed that such fluorophores were capable of sensing protons by intramolecular charge transfer (ICT). Empirical and quantum mechanical calculations showed that the electron donating effect of the dimethylamino group decreased the change in dipole moment on excitation which resulted in a fluorescence quantum yield remarkably enhanced as the solvent polarity increased. In alkaline media the fluorescence of DON was quenched owing to photoinduced electron transfer being disabled in acidic media. The pKa of the 1,8-naphthailimide dye was 6.70, which defines the dye as a highly efficient "off-on" switch. DON exhibited a typical aggregation-induced emission enhancement (AIEE) behavior that it is virtually nonemissive in organic solvent but highly luminescent in water, as a result of the restriction of free intramolecular rotation of a C-N bond and the non-planar configuration in the aggregate state. The hydrophobicity of octadecyl group provided DON with a fluorescent response to water based on AIEE and the water-dependent spectral characteristics of DON, and the AIEE of DON caused by the effect of water and formation of J-aggregation states. In the range of 0-79.8% (v/v), the fluorescence intensity of DON in acetone solution increased as a linear function of the water content. The optimum detection limits were of 0.011%, 0.0021%, and 0.0033% of water in acetone, ethanol, and acetonitrile, respectively. Satisfactory reproducibility, reversibility and a short response time were

  7. H89 enhances the sensitivity of cancer cells to glyceryl trinitrate through a purinergic receptor-dependent pathway

    PubMed Central

    Cortier, Marion; Boina-Ali, Rahamata; Racoeur, Cindy; Paul, Catherine; Solary, Eric; Jeannin, Jean-François; Bettaieb, Ali

    2015-01-01

    High doses of the organic nitrate glyceryl trinitrate (GTN), a nitric oxide (NO) donor, are known to trigger apoptosis in human cancer cells. Here, we show that such a cytotoxic effect can be obtained with subtoxic concentrations of GTN when combined with H89, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulphonamide.2HCl. This synergistic effect requires the generation of reactive oxygen species (ROS) from H89 and NO from GTN treatment that causes cGMP production and PKG activation. Furthermore, the GTN/H89 synergy was attenuated by inhibition of P2-purinergic receptors with suramin and competition with ATP/UDP. By down-regulating genes with antisense oligonucleotides, P2-purinergic receptors P2X3, P2Y1, and P2Y6 were found to have a role in creating this cytotoxic effect. Thus, H89 likely acts as an ATP mimetic synergizing with GTN to trigger apoptosis in aggressive cancer cells. PMID:25762630

  8. Synthesis and intravenous infusion into the rat of glyceryl bisacetoacetate, 1-acetoacetamido-2, 3-propane diol, and partially reduced glucosyl pentaacetoacetate.

    PubMed

    Birkhahn, R H; Clemens, R J; Hubbs, J C

    1997-07-01

    The efficacy of parenteral nutrition could be improved by finding a more effective energy source. Esters of short-chain fatty acids have exhibited some promise as alternatives to glucose. The present study reports on two new esters and one amide, each containing acetoacetate as the organic acid. The three compounds: glyceryl bisacetoacetate, N-2',3'-dihydroxypropyl-3-oxo-butanamide (1-acetoacetamido-2,3-propane diol), and partially reduced glucosyl pentaacetoacetate, were synthesized and then continuously infused into rats for 7 d. The infusion rate provided 50% of the rats' estimated metabolic energy requirements, and rats were fed with a reduced-energy oral diet that provided the remaining 50% of energy plus adequate protein. Rat groups for each compound were: (1) experimental-compound-infused and ad libitum-fed, (2) isoenergetic glucose-infused and pairfed, and (3) saline infused and pair-fed. Body-weight changes, N losses and N retention were measured daily. All rats died from partially reduced glucosyl pentaacetoacetate infusion at 100% and 50% of the intended rate. Rats infused with 1-acetoacetamido-2,3-propane diol failed to gain weight and to increase the plasma ketone-body concentration. Glyceryl bisacetoacetate produced hyperketonaemia, and weight gain and N variables that were similar to those for glucose-infused rats. It was concluded that only glyceryl bisacetoacetate would make a satisfactory parenteral nutrient.

  9. ORAL 1-O-OCTADECYL-2-O-BENZYL-SN-GLYCERO-3-CIDOFOVIR TARGETS THE LUNG AND IS EFFECTIVE AGAINST A LETHAL RESPIRATORY CHALLENGE WITH ECTROMELIA VIRUS IN MICE

    PubMed Central

    Hostetler, Karl Y.; Beadle, James R.; Trahan, Julissa; Aldern, Kathy A.; Owens, Gelita; Schriewer, Jill; Melman, Lora; Buller, R. Mark

    2007-01-01

    Hexadecyloxypropyl-cidofovir (HDP-CDV) has been shown to be orally active against lethal infection with orthopoxviruses including, mousepox, cowpox, vaccinia and rabbitpox. The alkoxyalkyl group provides oral absorption and reduces greatly the amount of drug reaching the kidney, the site of CDV’s dose limiting toxicity. However, the amount of HDP-CDV detected in lung, an important site of early poxvirus replication, is low and the reduction of viral titers in surviving animals is reduced moderately compared with the liver where poxvirus titers are virtually undetectable. We synthesized a novel glycerol ester of CDV, 1-O-octadecyl-2-O-benzyl-sn-glycero-3-CDV (ODBG-CDV), and compared its oral pharmacokinetics with that of HDP-CDV. Surprisingly, ODBG-CDV levels in lung are much higher and liver levels are reduced, suggesting that the compound is transported in small intestinal lymph instead the portal vein. ODBG-CDV has excellent in vitro activity in cells infected with ectromelia virus (ECTV). In mice infected with a lethal aerosol or intranasal challenge of ECTV, HDP-CDV and ODBG-CDV are equally effective in preventing death from disease. Other drugs esterified to 1-O-octadecyl-2-O-benzyl-sn-glycerol or 1-O-octadecyl-2-O-benzyl-sn-glycerol-3-phosphate may provide lung targeting for treatment of microbial or neoplastic diseases while reducing first pass removal by the liver during oral absorption. PMID:17123638

  10. Oral 1-O-octadecyl-2-O-benzyl-sn-glycero-3-cidofovir targets the lung and is effective against a lethal respiratory challenge with ectromelia virus in mice.

    PubMed

    Hostetler, Karl Y; Beadle, James R; Trahan, Julissa; Aldern, Kathy A; Owens, Gelita; Schriewer, Jill; Melman, Lora; Buller, R Mark

    2007-03-01

    Hexadecyloxypropyl-cidofovir (HDP-CDV) has been shown to be orally active against lethal infection with orthopoxviruses including, mousepox, cowpox, vaccinia and rabbitpox. The alkoxyalkyl group provides oral absorption and reduces greatly the amount of drug reaching the kidney, the site of CDV's dose limiting toxicity. However, the amount of HDP-CDV detected in lung, an important site of early poxvirus replication, is low and the reduction of viral titers in surviving animals is reduced moderately compared with the liver where poxvirus titers are virtually undetectable. We synthesized a novel glycerol ester of CDV, 1-O-octadecyl-2-O-benzyl-sn-glycero-3-CDV (ODBG-CDV), and compared its oral pharmacokinetics with that of HDP-CDV. Surprisingly, ODBG-CDV levels in lung are much higher and liver levels are reduced, suggesting that the compound is transported in small intestinal lymph instead the portal vein. ODBG-CDV has excellent in vitro activity in cells infected with ectromelia virus (ECTV). In mice infected with a lethal aerosol or intranasal challenge of ECTV, HDP-CDV and ODBG-CDV are equally effective in preventing death from disease. Other drugs esterified to 1-O-octadecyl-2-O-benzyl-sn-glycerol or 1-O-octadecyl-2-O-benzyl-sn-glycerol-3-phosphate may provide lung targeting for treatment of microbial or neoplastic diseases while reducing first pass removal by the liver during oral absorption.

  11. Investigation of mussel adhesive protein adsorption on polystyrene and poly(octadecyl methacrylate) using angle dependent XPS, ATR-FTIR, and AFM

    SciTech Connect

    Baty, A.M.; Suci, P.A.; Tyler, B.J.; Geesey, G.G.

    1996-02-10

    Despite many years of research effort, the molecular interactions that are responsible for microbial adhesion and fouling of surfaces remain obscure. An understanding of these interactions would contribute to the development of surfaces that resist colonization of microorganisms. The irreversible adsorption of mussel adhesive proteins (MAP) from the marine mussel Mytilus edulis has been investigated on polystyrene (PS) and poly(octadecyl methacrylate) (POMA) surfaces using angle resolved X-ray photoelectron spectroscopy (XPS), attenuated total reflection Fourier transform infrared (ATR-FTIR) spectrometry, and atomic force microscopy (AFM). Angle resolved XPS was used to quantify the elemental composition with depth of the upper 90 {angstrom} of the surface, and AFM was used to obtain the surface topography. The adsorption pattern of MAP, revealed by AFM images, is distinctly different on the two polymer surfaces and suggests that the substratum influences protein adhesion. The depth profiles of MAP, obtained from angle resolved XPS, show differences in nitrogen composition with depth for MAP adsorbed to PS and POMA. Infrared spectra of hydrated adsorbed MAP revealed significant differences in the amide III region and in two bands which may originate from residues in the tandemly repeated sequences of MAP. This data demonstrates that the chemistry of the polymer film that is present at the protein-polymer interface can influence protein-protein and protein-surface interactions.

  12. Construction of a novel cationic polymeric liposomes formed from PEGlated octadecyl-quaternized lysine modified chitosan/cholesterol for enhancing storage stability and cellular uptake efficiency.

    PubMed

    Wang, Hanjie; Zhao, Peiqi; Liang, Xiaofei; Song, Tao; Gong, Xiaoqun; Niu, Ruifang; Chang, Jin

    2010-08-15

    The design and construction of delivery vectors with high stability and effective cellular uptake efficiency is very important. In this study, a novel polymeric liposomes (PLs) formed from PEGlated octadecyl-quaternized lysine modified chitosan (OQLCS) and cholesterol with higher size stability and cellular uptake efficiency has been synthesized successfully. Compared to conventional liposomes (CLs; phosphatidyl choline/cholesterol), the calcein-loaded PLs exhibited a multi-lamellar structure with homogenous size diameter (200 nm) and high calcein encapsulation efficiency (about 92%). PLs could be stored at different temperature (25, 4, and -20 degrees C) and different medium (deionized water, phosphate-buffered saline, and human plasma solution) for up to 4 weeks without significant size change. The spectrophotometer fluorometry analysis and the flow cytometry analysis indicated that in comparison with CL, PLs with positive zeta potential facilitates the uptake of calcein by MCF-7 tumor cells. The data suggests that PLs may provide a new method to overcome the stability and enhance the uptake efficiency of CLs.

  13. Glyceryl trinitrate and caprylic acid for the mitigation of the Desulfovibrio vulgaris biofilm on C1018 carbon steel.

    PubMed

    Li, Y; Zhang, P; Cai, W; Rosenblatt, J S; Raad, I I; Xu, D; Gu, T

    2016-02-01

    Microbiologically influenced corrosion (MIC), also known as biocorrosion, is caused by corrosive biofilms. MIC is a growing problem, especially in the oil and gas industry. Among various corrosive microbes, sulfate reducing bacteria (SRB) are often the leading culprit. Biofilm mitigation is the key to MIC mitigation. Biocide applications against biofilms promote resistance over time. Thus, it is imperative to develop new biodegradable and cost-effective biocides for large-scale field applications. Using the corrosive Desulfovibrio vulgaris (an SRB) biofilm as a model biofilm, this work demonstrated that a cocktail of glyceryl trinitrate (GTN) and caprylic acid (CA) was very effective for biofilm prevention and mitigation of established biofilms on C1018 carbon steel coupons. The most probable number sessile cell count data and confocal laser scanning microscope biofilm images proved that the biocide cocktail of 25 ppm (w/w) GTN + 0.1% (w/w) CA successfully prevented the D. vulgaris biofilm establishment on C1018 carbon steel coupons while 100 ppm GTN + 0.1% CA effectively mitigated pre-established D. vulgaris biofilms on C1018 carbon steel coupons. In both cases, the cocktails were able to reduce the sessile cell count from 10(6) cells/cm(2) to an undetectable level.

  14. Nanoassemblies containing a fluorouracil/zidovudine glyceryl prodrug with phospholipase A2-triggered drug release for cancer treatment.

    PubMed

    Jin, Yiguang; Yang, Fang; Du, Lina

    2013-12-01

    Secretory phospholipase A2 (sPLA2), which is overexpressed in many tumors, cleaves ester bonds at the sn-2 position of phospholipids. A PLA2-sensitive amphiphilic prodrug, 1-O-octadecyl-2-(5-fluorouracil)-N-acetyl-3-zidovudine-phosphorylglycerol (OFZG), was synthesized and used to prepare nanoassemblies through the injection of a mixture of OFZG/cholesterol/Tween 80 (2:1:0.1, mol:mol:mol) into water. Cholesterol and Tween 80 was incorporated into the OFZG monolayers at the air/water interface to yield nanoassemblies. The resulting nanoassemblies exhibited a narrow size distribution with a mean size of 77.8nm and were stable due to their high surface charges. The in vitro experiments showed that PLA2 degraded OFZG. The nanoassemblies exhibited higher anticancer activity than the parent drug 5-fluorouracil (5-FU) in COLO205, HT-28, and HCT-116 cells. The intravenous (i.v.) administration of the nanoassemblies into mice resulted in the rapid elimination of OFZG from the circulation and its distribution mainly in the liver, lung, spleen, and kidney. After their injection into tumor-bearing mice, the nanoassemblies exhibited anticancer efficiency comparable to that of 5-FU, even though the nanoassemblies contained concentrations of only 1/10 of the molar amount of 5-FU. The lessons learned from the study and methods for the design of PLA2-sensitive amphiphilic prodrugs are also discussed. Enzyme-sensitive amphiphilic combinatorial prodrugs and prodrug-loaded nanoassemblies may represent a new strategy for anticancer drug design.

  15. Programmable flow-based dynamic sorptive microextraction exploiting an octadecyl chemically modified rotating disk extraction system for the determination of acidic drugs in urine.

    PubMed

    Manzo, Valentina; Miró, Manuel; Richter, Pablo

    2014-11-14

    A novel automatic sorptive microextraction approach combining sequential injection-based programmable flow with rotating disk sorptive extraction (RDSE) is proposed for the clean-up and concentration of low polarity organic species in urine samples. Non-steroidal anti-inflammatory drugs (NSAIDs), namely, ketoprofen, naproxen, diclofenac and ibuprofen, were selected as model analytes in a proof-of-concept design, and they were further determined by liquid chromatographic (LC) assays. The extracting phase consisted of octadecyl (C18) chemically bonded silica embedded in a polytetrafluoroethylene (PTFE) substrate. The thin film was immobilized onto the surface of an in-house prepared rotating PTFE disk in a dedicated flow-through chamber. The programmable flow-based microextraction method operates under kinetic principles and features software-controlled sample loading and dynamic sorptive unidirectional-flow microextraction for as little as 10 min, followed by matrix clean-up and in-line elution with methanol. The hydrophobic thin-film extracting phase was demonstrated to be reusable for at least 15 consecutive extractions in urine without removing or changing the disk. The relative recoveries of the NSAIDs in urine ranged from 101 to 106% using a matrix-matched calibration curve, with extraction efficiencies of 30-38% using a dynamic regime, an enrichment factor of approximately 17 for 10 mL sample and relative standard deviations (RSD) between 3 and 6%. The detection limits (3 × S/N ratio) of the in-line sample preparation method coupled to LC-UV detection ranged from 0.022 to 0.044 mg L(-1). Using NSAID monitored in urine from individuals who received oral administration of ibuprofen and diclofenac, the automatic sample handling method was proven to be efficient for urine clean-up and the determination of acidic drugs at biologically relevant levels.

  16. Octadecyl Chains Immobilized onto Hyaluronic Acid Coatings by Thiol-ene "Click Chemistry" Increase the Surface Antimicrobial Properties and Prevent Platelet Adhesion and Activation to Polyurethane.

    PubMed

    Felgueiras, Helena P; Wang, L M; Ren, K F; Querido, M M; Jin, Q; Barbosa, M A; Ji, J; Martins, M C L

    2017-03-08

    Infection and thrombus formation are still the biggest challenges for the success of blood contact medical devices. This work aims the development of an antimicrobial and hemocompatible biomaterial coating through which selective binding of albumin (passivant protein) from the bloodstream is promoted and, thus, adsorption of other proteins responsible for bacterial adhesion and thrombus formation can be prevented. Polyurethane (PU) films were coated with hyaluronic acid, an antifouling agent, that was previously modified with thiol groups (HA-SH), using polydopamine as the binding agent. Octadecyl acrylate (C18) was used to attract albumin since it resembles the circulating free fatty acids and albumin is a fatty acid transporter. Thiol-ene "click chemistry" was explored for C18 immobilization on HA-SH through a covalent bond between the thiol groups from the HA and the alkene groups from the C18 chains. Surfaces were prepared with different C18 concentrations (0, 5, 10, and 20%) and successful immobilization was demonstrated by scanning electron microscopy (SEM), water contact angle determinations, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR). The ability of surfaces to bind albumin selectively was determined by quartz crystal microbalance with dissipation (QCM-D). Albumin adsorption increased in response to the hydrophobic nature of the surfaces, which augmented with C18 saturation. HA-SH coating reduced albumin adsorption to PU. C18 immobilized onto HA-SH at 5% promoted selective binding of albumin, decreased Staphylococcus aureus adhesion and prevented platelet adhesion and activation to PU in the presence of human plasma. C18/HA-SH coating was established as an innovative and promising strategy to improve the antimicrobial properties and hemocompatibility of any blood contact medical device.

  17. Fusion between Newcastle disease virus and erythrocyte ghosts using octadecyl Rhodamine B fluorescence assay produces dequenching curves that fit the sum of two exponentials.

    PubMed Central

    Cobaleda, C; García-Sastre, A; Villar, E

    1994-01-01

    The kinetics of fusion between Newcastle disease virus and erythrocyte ghosts has been investigated with the octadecyl Rhodamine B chloride assay [Hoekstra, De Boer, Klappe, and Wilschut (1984) Biochemistry 23, 5675-5681], and the data from the dequenching curves were fitted by non-linear regression to currently used kinetic models. We used direct computer-assisted fitting of the dequenching curves to the mathematical equations. Discrimination between models was performed by statistical analysis of different fits. The experimental data fit the exponential model previously published [Nir, Klappe, and Hoekstra (1986) Biochemistry 25, 2155-2161] but we describe for the first time that the best fit was achieved for the sum of two exponential terms: A1[1-exp(-k1t)]+A2[1-exp(-k2t)]. The first exponential term represents a fast reaction and the second a slow dequenching reaction. These findings reveal the existence of two independent, but simultaneous, processes during the fusion assay. In order to challenge the model and to understand the meaning of both equation, fusion experiments were carried out under different conditions well known to affect viral fusion (changes in pH, temperature and ghost concentration, and the presence of disulphide-reducing agents or inhibitors of viral neuraminidase activity), and the same computer fitting scheme was followed. The first exponential equation represents the viral protein-dependent fusion process itself, because it is affected by the assay conditions. The second exponential equation accounts for a nonspecific reaction, because it is completely independent of the assay conditions and hence of the viral proteins. An interpretation of this second process is discussed in terms of probe transfer between vesicles. PMID:8002938

  18. Haemodynamic effects of glyceryl trinitrate following repeated application of a transdermal delivery system with a phasic release profile.

    PubMed

    Wiegand, A; Bonn, R; Wagner, F; Trenk, D; Jähnchen, E

    1991-01-01

    The haemodynamic effects and plasma concentrations of glyceryl trinitrate (GTN) and its dinitrate metabolites were investigated in 8 healthy male volunteers during 5 days of application of a new transdermal delivery system (TDS) with time-dependent release characteristics, which were considered to prevent or to diminish development of nitrate tolerance. On the first and fifth day of administration the following haemodynamic parameters were determined: digital pulse ratio of height of systolic peak to height of dicrotic wave (i.e. a/b-ratio), heart rate and systolic blood pressure under orthostatic conditions. Peak plasma concentrations of GTN were 139 and 155 pg.ml-1 on the first and fifth day of treatment, and the corresponding trough concentrations (i.e. 24 h after administration) were 52.5 and 36.6 pg.ml-1, respectively. Compared to placebo, the area under the effect curve of the a/b-ratio of the digital pulse was increased on the first (25.6%) and fifth day (13%). A significant increase of heart rate and a decrease of systolic blood pressure were seen only on the first day of treatment. The haemodynamic effects of sublingual GTN 0.8 mg were reduced by 69% (a/b-ratio) and 52% (standing heart rate) on the fifth day compared to the pretreatment values. Thus, the phasic release of GTN from the new TDS can be demonstrated by the time course of the plasma concentrations of GTN and its metabolites. Nevertheless, following repeated administration the hemodynamic effects are blunted.

  19. Solid-phase extraction of ultratrace uranium(VI) in natural waters using octadecyl silica membrane disks modified by tri-n-octylphosphine oxide and its spectrophotometric determination with dibenzoylmethane.

    PubMed

    Shamsipur, M; Ghiasvand, A R; Yamini, Y

    1999-11-01

    A simple and reliable method for rapid extraction and determination of uranium in natural waters using octadecyl-bonded silica membrane disks modified with tri-n-octylphosphine oxide (TOPO) and spectrophotometry with dibenzoylmethane is presented. Extraction efficiency and the influence of sample matrix, type, and optimum amount of extractant, flow rates, and type and minimum amount of organic eluent were evaluated. The maximal capacity of the membrane disks modified by 50 mg of TOPO was found to be 4033 micrograms of uranium. The limit of detection of the proposed method is 100 ng/1000 mL. The method was applied to the extraction and determination of uranium in natural waters.

  20. Synthesis of a stationary phase based on silica modified with branched octadecyl groups by Michael addition and photoinduced thiol-yne click chemistry for the separation of basic compounds.

    PubMed

    Huang, Guang; Ou, Junjie; Wang, Hongwei; Ji, Yongsheng; Wan, Hao; Zhang, Zhang; Peng, Xiaojun; Zou, Hanfa

    2016-04-01

    A novel silica-based stationary phase with branched octadecyl groups was prepared by the sequential employment of the Michael addition reaction and photoinduced thiol-yne click chemistry with 3-aminopropyl-functionalized silica microspheres as the initial material. The resulting stationary phase denoted as SiO2 -N(C18)4 was characterized by elemental analysis, FTIR spectroscopy and Raman spectroscopy, demonstrating the existence of branched octadecyl groups in silica microspheres. The separations of benzene homologous compounds, acid compounds and amine analogues were conducted, demonstrating mixed-mode separation mechanism on SiO2 -N(C18)4 . Baseline separation of basic drugs mixture was acquired with the mobile phase of acetonitrile/H2 O (5%, v/v). SiO2 -N(C18)4 was further applied to separate Corydalis yanhusuo Wang water extracts, and more baseline separation peaks were obtained for SiO2 -N(C18)4 than those on Atlantis dC18 column. It can be expected that this new silica-based stationary phase will exhibit great potential in the analysis of basic compounds.

  1. Comparative studies of multi-walled carbon nanotubes (MWNTs) and octadecyl (C18) as sorbents in passive sampling devices for biomimetic uptake of polycyclic aromatic hydrocarbons (PAHs) from soils.

    PubMed

    Li, Shibin; Anderson, Todd A; Maul, Jonathan D; Shrestha, Babina; Green, Micah J; Cañas-Carrell, Jaclyn E

    2013-09-01

    To avoid overestimating the risk of polycyclic aromatic hydrocarbons (PAHs), research is needed to evaluate the bioavailable portion of PAHs in the environment. However, limited PSDs were developed for a terrestrial soil system. In this study, two sorbents, octadecyl (C18) and multi-walled carbon nanotubes (MWNTs), were individually evaluated as sorbents in passive sampling devices (PSDs) as biomimetic samplers to assess the uptake of PAHs from soil. C18-PSDs were an excellent biomimetic tool for PAHs with a low molecular weight in complex exposure conditions with different soil types, types of PAHs, aging periods, and initial PAH concentrations in soil. The utility of MWNT-PSDs was limited by extraction efficiencies of PAHs from MWNTs. However, when compared to C18-PSDs, they had higher adsorption capacities and were less expensive. This study provides data regarding useful techniques that can be used in risk assessment to assess the bioavailability of PAHs in soil.

  2. Capillary electrochromatography with monolithic silica column: I. Preparation of silica monoliths having surface-bound octadecyl moieties and their chromatographic characterization and applications to the separation of neutral and charged species.

    PubMed

    Allen, Darin; El Rassi, Ziad

    2003-01-01

    Monolithic silica columns with surface-bound octadecyl (C18) moieties have been prepared by a sol-gel process in 100 microm ID fused-silica capillaries for reversed-phase capillary electrochromatography of neutral and charged species. The reaction conditions for the preparation of the C18-silica monoliths were optimized for maximum surface coverage with octadecyl moieties in order to maximize retention and selectivity toward neutral and charged solutes with a sufficiently strong electroosmotic flow (> 2 mm/s) to yield rapid analysis time. Furthermore, the effect of the pore-tailoring process on the silica monoliths was performed over a wide range of treatment time with 0.010 M ammonium hydroxide solution in order to determine the optimum time and conditions that yield mesopores of narrow pore size distribution that result in high separation efficiency. Under optimum column fabrication conditions and optimum mobile phase composition and flow velocity, the average separation efficiency reached 160 000 plates/m, a value comparable to that obtained on columns packed with 3 microm C18-silica particles with the advantages of high permeability and virtually no bubble formation. The optimized monolithic C18-silica columns were evaluated for their retention properties toward neutral and charged analytes over a wide range of mobile phase compositions. A series of dimensionless retention parameters were evaluated and correlated to solute polarity and electromigration property. A dimensionless mobility modulus was introduced to describe charged solute migration and interaction behavior with the monolithic C18-silica in a counterflow regime during capillary electrochromatography (CEC )separations. The mobility moduli correlated well with the solute hydrophobic character and its charge-to-mass ratio.

  3. The Effects of Platelet-Activating Factor (PAF) and a PAF Antagonist (CV-3988) on Smoke Inhalation Injury in an Ovine Model,

    DTIC Science & Technology

    1992-03-01

    decyl-2-acetyl-sn-glyceryl-3- phosphorylcholine ) has following PAF injection. In models of endotoxin shock, been reported to be one of the principal...instillation of 1-0-octadecyl-2- 25. Traber DL, Herndon DN, Stein MD, et al: The pulmonary lesion acetyl-sn-glyceryl-3- phosphorylcholine or of native platelet-ac...glyceryl ether phosphorylcholine infusion in the change (abstr). Proceedings of the American Burn Association rabbit. Am Rev Respir Dis 124:416, 1981 22nd

  4. Glyceryl trinitrate metabolism in the quail embryo by the glutathione S-transferases leads to a perturbation in redox status and embryotoxicity.

    PubMed

    Bardai, Ghalib K; Hales, Barbara F; Sunahara, Geoffrey I

    2013-07-01

    Exposure of stage 9 quail (Coturnix coturnix japonica) embryos to glyceryl trinitrate (GTN) induces malformations that were associated in previous studies with an increase in protein nitration. Increased nitration suggests metabolism of GTN by the embryo. The goals of this study were to characterize the enzymes and co-factors required for GTN metabolism by quail embryos, and to determine the effects of in ovo treatment with N-acetyl cysteine (NAC), a precursor of glutathione (GSH), on GTN embryotoxicity. GTN treatment of quail embryos resulted in an increase in nitrite, a decrease in total GSH, and an increase in the ratio of NADP(+)/NADPH, indicating that redox balance may be compromised in exposed embryos. Glutathione S-transferases (GSTs; EC 2.5.1.18) purified from the whole embryo (K(m) 0.84 mM; V(max) 36 μM/min) and the embryonic eye (K(m) 0.20 mM; V(max) 30 μM/min) had GTN-metabolizing activity (1436 and 34 nmol/min/mg, respectively); the addition of ethacrynic acid, an inhibitor of GST activity, decreased GTN metabolism. Peptide sequencing of the GST isozymes indicated that alpha- or mu-type GSTs in the embryo and embryonic eye had GTN metabolizing activity. NAC co-treatment partially protected against the effects of GTN exposure. Thus, GTN denitration by quail embryo GSTs may represent a key initial step in the developmental toxicity of GTN.

  5. Analysis of curing of a sustained release coating formulation by application of NIR spectroscopy to monitor changes associated with glyceryl monostearate.

    PubMed

    Howland, Harris; Fahmy, Raafat; Hoag, Stephen W

    2015-01-01

    For controlled release, latex or pseudolatex coatings to function as designed, it must be cured at temperatures at or slightly above the polymer's glass transition temperature. The focus of this study is to develop an understanding of the curing process and to develop near infrared spectroscopy as a tool for monitoring curing. Differential scanning calorimetry studies were used to determine how the thermal properties of glyceryl monostearate (GMS) and its polymorphic forms relate to the extent of Eudragit® polymer coat curing at different curing temperatures. The different GMS melting endotherms were used to monitor the extent of curing and as references for model development. The calculated melting peak areas for the GMS were plotted versus time and found to be dependent on time and temperature used for curing. Principal component analysis and parallel factor analysis were used to investigate the effect of curing on the films and showed that spectral changes could be could be directly related to the changes associated with the GMS during curing. Partial least square models developed could predict the extent of curing and the final state of GMS post curing.

  6. Glyceryl Tribenzoate: A Flavoring Ingredient, Inhibits the Adoptive Transfer of Experimental Allergic Encephalomyelitis via TGF-β: Implications for Multiple Sclerosis Therapy

    PubMed Central

    Mondal, Susanta; Dasarathi, Sridevi; Pahan, Kalipada

    2017-01-01

    Multiple sclerosis (MS) is the most common autoimmune demyelinating disease of the central nervous system (CNS). Here, we have explored a novel use of glyceryl tribenzoate (GTB), a flavoring ingredient, in ameliorating the disease process of experimental allergic encephalomyelitis (EAE), an animal model of MS, via TGF-β. Oral feeding of GTB suppressed clinical symptoms of adoptively-transferred relapsing-remitting (RR) EAE in recipient mice and suppressed the generation of encephalitogenic T cells in donor mice. GTB also attenuated clinical symptoms of RR-EAE in PLP-TCR transgenic mice and chronic EAE in male C57/BL6 mice. Accordingly, GTB also suppressed perivascular cuffing, preserved the integrity of blood-brain barrier and blood-spinal cord barrier, inhibited inflammation, and stopped demyelination in the CNS of EAE mice. Interestingly, GTB treatment upregulated TGF-β and enriched regulatory T cells (Tregs) in splenocytes as well as in vivo in EAE mice. Blocking TGF-β by neutralizing antibodies abrogated GTB-mediated enrichment of Tregs and protection of EAE. These results suggest that oral GTB may be considered as a possible therapy for MS patients. PMID:28367355

  7. Safety assessment for octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate (CAS Reg. No. 2082-79-3) from use in food contact applications.

    PubMed

    Neal-Kluever, April P; Bailey, Allan B; Hatwell, Karen R

    2015-12-01

    Octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (CAS Reg. No. 2082-79-3), currently marketed as Irganox 1076 (I-76), is a sterically hindered phenolic antioxidant used in a variety of organic substrates, including those used in the manufacture of food contact articles. In 2012, the US Food and Drug Administration (USFDA), Office of Food Additive Safety (OFAS), initiated a post-market re-evaluation of the food contact applications of I-76. This project aimed to ensure that current dietary exposures from the use of I-76 in food contact articles are accurately captured and the safety assessment considered all relevant and available toxicological information. To accomplish these aims, the USFDA reviewed the available toxicological studies and chemistry information on food contact applications of I-76. Based on this in-depth analysis, a NOAEL of 64 mg/kg-bw/d (female rats) from a chronic rat study and a cumulative estimated dietary intake (CEDI) of 4.5 mg/p/d, was used to calculate a margin of exposure (MOE) of ∼850. We concluded that the previous and current exposure levels provide an adequate margin of safety (MOS) and remain protective of human health for the regulated uses.

  8. Optimisation of octadecyl (C18) sorbent amount in QuEChERS analytical method for the accurate organophosphorus pesticide residues determination in low-fatty baby foods with response surface methodology.

    PubMed

    Georgakopoulos, Panagiotis; Zachari, Rodanthi; Mataragas, Marios; Athanasopoulos, Panagiotis; Drosinos, Eleftherios H; Skandamis, Panagiotis N

    2011-09-15

    Three low-fatty baby food matrices were fortified with 0.01-0.2mg/kg of phorate, diazinon, chlorpyrifos and methidathion. A "quick, easy, cheap, effective, rugged and safe" - like method (QuEChERS) was used. Quantities of octadecyl (C18) sorbent differed with fortification level and matrix fat, based on central composite experimental design. Quantification was performed by Nitrogen-Phosphorus Detector gas chromatography, using matrix-matched standards. The highest (p<0.05) recoveries were observed for methidathion, the lowest fortification levels for a specific C18 amount and the lowest C18 amounts. In meals containing vegetables (1.9% fat) and lamb (3.0% fat), 180-210mg C18 gave recoveries from 67.0% to 105.0% and absence of co-extracts. Yogurt dessert (4.5% fat) required 200-230mg C18 for similar results. Recoveries could also be predicted with <20% error by a polynomial model. The results suggest that modified QuEChERS could be effectively used in the low-fatty baby meals residue analysis.

  9. Enrichment of trace amounts of copper(II) ions in water samples using octadecyl silica disks modified by a Schiff base ionophore prior to flame atomic absorption spectrometric determination.

    PubMed

    Fathi, S A M; Yaftian, M R

    2009-05-15

    Bis(5-bromo-2-hydroxybenzaldehyde)-1,2-propanediimine is synthesized by the reaction of 5-bromo-2-hydroxybenzaldehyde and 1,2-diaminopropane in ethanol. This ligand is used as a modifier of octadecyl silica disks for preconcentration of trace amounts of copper(II) ions, followed by nitric acid elution and flame atomic absorption spectrometric (FAAS) determination. The effect of parameters influencing the extraction efficiency, i.e. pH of the sample solutions, amount of the Schiff base, type and volume of stripping reagent, sample and eluent flow rates were evaluated. Under optimum experimental conditions, the capacity of the membrane disks modified by 4mg of the ligand was found to be 247.7 (+/-2.1)mug of copper. The detection limit and the concentration factor of the presented method are 2.4ng/l and greater than 400, respectively. The method was applied to the extraction, recovery and detection of copper in different synthetic and water samples.

  10. Glyceryl triacetate for Canavan disease: a low-dose trial in infants and evaluation of a higher dose for toxicity in the tremor rat model.

    PubMed

    Madhavarao, C N; Arun, P; Anikster, Y; Mog, S R; Staretz-Chacham, O; Moffett, J R; Grunberg, N E; Gahl, W A; Namboodiri, A M A

    2009-10-01

    Canavan disease (CD) is a fatal dysmyelinating genetic disorder associated with aspartoacylase deficiency, resulting in decreased brain acetate levels and reduced myelin lipid synthesis in the developing brain. Here we tested tolerability of a potent acetate precursor, glyceryl triacetate (GTA), at low doses in two infants diagnosed with CD, aged 8 and 13 months. Much higher doses of GTA were evaluated for toxicity in the tremor rat model of CD. GTA was given orally to the infants for up to 4.5 and 6 months, starting at 25 mg/kg twice daily, doubling the dose weekly until a maximum of 250 mg/kg reached. Wild-type and tremor rat pups were given GTA orally twice daily, initially at a dose of 4.2 g/kg from postnatal days 7 through 14, and at 5.8 g/kg from day 15 through 23, and thereafter in food (7.5%) and water (5%). At the end of the trial (approximately 90 to 120 days) sera and tissues from rats were analysed for changes in blood chemistry and histopathology. GTA treatment caused no detectable toxicity and the patients showed no deterioration in clinical status. In the high-dose animal studies, no significant differences in the mean blood chemistry values occurred between treated and untreated groups, and no lesions indicating toxicity were detectable in any of the tissues examined. Lack of GTA toxicity in two CD patients in low-dose trials, as well as in high-dose animal studies, suggests that higher, effective dose studies in human CD patients are warranted.

  11. Progress toward acetate supplementation therapy for Canavan disease: glyceryl triacetate administration increases acetate, but not N-acetylaspartate, levels in brain.

    PubMed

    Mathew, Raji; Arun, Peethambaran; Madhavarao, Chikkathur N; Moffett, John R; Namboodiri, M A Aryan

    2005-10-01

    Canavan disease (CD) is a fatal genetic neurodegenerative disorder caused by mutations in the gene for aspartoacylase, an enzyme that hydrolyzes N-acetylaspartate (NAA) into L-aspartate and acetate. Because aspartoacylase is localized in oligodendrocytes, and NAA-derived acetate is incorporated into myelin lipids, we hypothesize that an acetate deficiency in oligodendrocytes is responsible for the pathology in CD, and we propose acetate supplementation as a possible therapy. In our preclinical efforts toward this goal, we studied the effectiveness of orally administered glyceryl triacetate (GTA) and calcium acetate for increasing acetate levels in the murine brain. The concentrations of brain acetate and NAA were determined simultaneously after intragastric administration of GTA. We found that the acetate levels in brain were increased in a dose- and time-dependent manner, with a 17-fold increase observed at 1 to 2 h in 20- to 21-day-old mice at a dose of 5.8 g/kg GTA. NAA levels in the brain were not significantly increased under these conditions. Studies using mice at varying stages of development showed that the dose of GTA required to maintain similarly elevated acetate levels in the brain increased with age. Also, GTA was significantly more effective as an acetate source than calcium acetate. Chronic administration of GTA up to 25 days of age did not result in any overt pathology in the mice. Based on these results and the current Food and Drug Administration-approved use of GTA as a food additive, we propose that it is a potential candidate for use in acetate supplementation therapy for CD.

  12. Final amended report on the safety assessment of Ammonium Thioglycolate, Butyl Thioglycolate, Calcium Thioglycolate, Ethanolamine Thioglycolate, Ethyl Thioglycolate, Glyceryl Thioglycolate, Isooctyl Thioglycolate, Isopropyl Thioglycolate, Magnesium Thioglycolate, Methyl Thioglycolate, Potassium Thioglycolate, Sodium Thioglycolate, and Thioglycolic Acid.

    PubMed

    Burnett, Christina L; Bergfeld, Wilma F; Belsito, Donald V; Klaassen, Curtis D; Marks, James G; Shank, Ronald C; Slaga, Thomas J; Snyder, Paul W; Andersen, F Alan

    2009-01-01

    This safety assessment includes Ammonium and Glyceryl Thioglycolate and Thioglycolic Acid Butyl, Calcium, Ethanolamine, Ethyl, Isooctyl, Isopropyl, Magnesium, Methyl, Potassium, and Sodium Thioglycolate, as used in cosmetics. Thioglycolates penetrate skin and distribute to the kidneys, lungs, small intestine, and spleen; excretion is primarily in urine. Thioglycolates were slightly toxic in rat acute oral toxicity studies. Thioglycolates are minimal to severe ocular irritants. Thioglycolates can be skin irritants in animal and in vitro tests, and can be sensitizers. A no-observable-adverse-effect level for reproductive and developmental toxicity of 100 mg/kg per day was determined using rats. Thioglycolates were not mutagenic, and there was no evidence of carcinogenicity. Thioglycolates were skin irritants in some clinical tests. Clinically significant adverse reactions to these ingredients used in depilatories are not commonly seen, suggesting current products are formulated to be practically nonirritating under conditions of recommended use. Formulators should take steps necessary to assure that current practices are followed.

  13. Effect of Treatment Delay, Stroke Type, and Thrombolysis on the Effect of Glyceryl Trinitrate, a Nitric Oxide Donor, on Outcome after Acute Stroke: A Systematic Review and Meta-Analysis of Individual Patient from Randomised Trials

    PubMed Central

    Bath, Philip M.; Woodhouse, Lisa; Krishnan, Kailash; Anderson, Craig; Berge, Eivind; Ford, Gary A.; Robinson, Thompson G.; Saver, Jeffrey L.; Sprigg, Nikola; Wardlaw, Joanna M.; in Acute Stroke Collaboration (BASC), Blood pressure

    2016-01-01

    Background. Nitric oxide (NO) donors are a candidate treatment for acute stroke and two trials have suggested that they might improve outcome if administered within 4–6 hours of stroke onset. We assessed the safety and efficacy of NO donors using individual patient data (IPD) from completed trials. Methods. Randomised controlled trials of NO donors in patients with acute or subacute stroke were identified and IPD sought from the trialists. The effect of NO donor versus control on functional outcome was assessed using the modified Rankin scale (mRS) and death, by time to randomisation. Secondary outcomes included measures of disability, mood, and quality of life. Results. Five trials (4,197 participants) were identified, all involving glyceryl trinitrate (GTN). Compared with control, GTN lowered blood pressure by 7.4/3.3 mmHg. At day 90, GTN did not alter any clinical measures. However, in 312 patients randomised within 6 hours of stroke onset, GTN was associated with beneficial shifts in the mRS (odds ratio (OR) 0.52, 95% confidence interval (CI) 0.34–0.78) and reduced death (OR 0.32, 95% CI 0.14–0.78). Conclusions. NO donors do not alter outcome in patients with recent stroke. However, when administered within 6 hours, NO donors might improve outcomes in both ischaemic and haemorrhagic stroke. PMID:27190674

  14. Final report on the safety assessment of Ricinus Communis (Castor) Seed Oil, Hydrogenated Castor Oil, Glyceryl Ricinoleate, Glyceryl Ricinoleate SE, Ricinoleic Acid, Potassium Ricinoleate, Sodium Ricinoleate, Zinc Ricinoleate, Cetyl Ricinoleate, Ethyl Ricinoleate, Glycol Ricinoleate, Isopropyl Ricinoleate, Methyl Ricinoleate, and Octyldodecyl Ricinoleate.

    PubMed

    2007-01-01

    The oil derived from the seed of the Ricinus communis plant and its primary constituent, Ricinoleic Acid, along with certain of its salts and esters function primarily as skin-conditioning agents, emulsion stabilizers, and surfactants in cosmetics, although other functions are described. Ricinus Communis (Castor) Seed Oil is the naming convention for castor oil used in cosmetics. It is produced by cold pressing the seeds and subsequent clarification of the oil by heat. Castor oil does not contain ricin because ricin does not partition into the oil. Castor oil and Glyceryl Ricinoleate absorb ultraviolet (UV) light, with a maximum absorbance at 270 nm. Castor oil and Hydrogenated Castor Oil reportedly were used in 769 and 202 cosmetic products, respectively, in 2002; fewer uses were reported for the other ingredients in this group. The highest reported use concentration (81%) for castor oil is associated with lipstick. Castor oil is classified by Food and Drug Administration (FDA) as generally recognized as safe and effective for use as a stimulant laxative. The Joint Food and Agriculture Organization (FAO)/World Health Organization (WHO) Expert Committee on Food Additives established an acceptable daily castor oil intake (for man) of 0 to 0.7 mg/kg body weight. Castor oil is hydrolyzed in the small intestine by pancreatic enzymes, leading to the release of glycerol and Ricinoleic Acid, although 3,6-epoxyoctanedioic acid, 3,6-epoxydecanedioic acid, and 3,6-epoxydodecanedioic acid also appear to be metabolites. Castor oil and Ricinoleic Acid can enhance the transdermal penetration of other chemicals. Although chemically similar to prostaglandin E(1), Ricinoleic Acid did not have the same physiological properties. These ingredients are not acute toxicants, and a National Toxicology Program (NTP) subchronic oral toxicity study using castor oil at concentrations up to 10% in the diet of rats was not toxic. Other subchronic studies of castor oil produced similar findings

  15. Quantification of ultra-trace amounts of copper by using off-line solid phase extraction-flame atomic absorption spectrometric determination through the octadecyl silica-bonded phase membrane (OSPM) C18 disks impregnated with 2,2'-[ethane-1,2-diylbis(thio)]dianiline.

    PubMed

    Mohammadhosseini, Majid; Soliemani, Esmaeil

    2014-07-01

    This study reports a very selective, easy, and precise method for rapid separation of trace amounts of copper in aqueous samples using octadecyl silica-bonded phase membrane disks modified by 2,2'-[ethane-1,2-diylbis(thio)]dianiline (EDTD) combined with flame atomic absorption spectrometric determination. In addition, the synthesis and spectral characterization of EDTD have been described in detail. All the affecting experimental variables such as pH, amount of modifier, eluent type, sample and eluent flow rate, interfering ions, and disk capacity were also investigated. The target analyte (trace copper) was quantitatively retained at pH = 4 and eluted with 6.0 mL of 0.5 M HNO3 at flow rates of 40 and 10 mL min−1 for analyte passage and elution steps, respectively, through the disks modified with 17.0 mg of EDTD. The proposed method also allows an enrichment factor of about 500 and has a detection limit of 0.005 ng mL−1. The method has been successfully applied for isolation and determination of copper in different water samples, peppers, and standard alloys.

  16. 21 CFR 582.1324 - Glyceryl monostearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE General Purpose Food... substance is generally recognized as safe when used in accordance with good manufacturing or feeding practice....

  17. 21 CFR 172.811 - Glyceryl tristearate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... glycerol content: Not to exceed 0.5 percent. Unsaponifiable matter: Not to exceed 0.5 percent. Melting point (Class II): 69 °C-73 °C. (c) The additive is used or intended for use as follows when standards...

  18. 21 CFR 172.811 - Glyceryl tristearate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... glycerol content: Not to exceed 0.5 percent. Unsaponifiable matter: Not to exceed 0.5 percent. Melting point (Class II): 69 °C-73 °C. (c) The additive is used or intended for use as follows when standards...

  19. 21 CFR 172.811 - Glyceryl tristearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... glycerol content: Not to exceed 0.5 percent. Unsaponifiable matter: Not to exceed 0.5 percent. Melting point (Class II): 69 °C-73 °C. (c) The additive is used or intended for use as follows when standards...

  20. 21 CFR 172.811 - Glyceryl tristearate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... reacting stearic acid with glycerol in the presence of a suitable catalyst. (b) The food additive meets the... number: 186-192. Hydroxyl number: Not to exceed 5.0. Free glycerol content: Not to exceed 0.5...

  1. Glyceryl trinitrate for the treatment of preterm labor

    PubMed Central

    Çalışkan, Şafak; Narin, Mehmet Ali; Dede, Faruk Suat; Narin, Raziye; Dede, Hülya; Kandemir, Ömer

    2015-01-01

    Objective This study was conducted to compare the tocolytic efficacy of glyceryltrinitrate (GTN) with that of magnesium sulfate (MgSO4) and to investigate serum nitric oxide metabolites before and after tocolysis. Material and Methods In total, 48 women between 27 and 34 weeks’ gestation with threatened preterm labor and intact membranes were randomly allocated to receive either GTN or MgSO4 tocolysis. Main outcome measures included tocolytic efficacy and maternal side effect(s) of the tocolytic agent. Obstetric and neonatal outcomes as well as pretreatment and posttreatment nitric oxide (NO) metabolites were assessed. Results Forty-one patients were included into the final analysis. Uterine contraction cessation times were 3.66±1.28 and 6.83±3.47 hours for GTN and MgSO4 groups, respectively. Similarly, maternal side effects were significantly lower in the GTN group than in the MgSO4 group, and no serious maternal side effects were recorded. Serum NO metabolite levels before treatment were significantly lower in the treatment groups than in the controls. Serum nitrite levels were significantly increased after tocolytic treatment both in MgSO4 and GTN groups. Conclusion GTN effectively delays preterm delivery and reduces neonatal morbidity and mortality with less maternal side effects and seems to be an effective and safe alternative to MgSO4. PMID:26401112

  2. Treatment of Xerosis with a Topical Formulation Containing Glyceryl Glucoside, Natural Moisturizing Factors, and Ceramide

    PubMed Central

    Kausch, Martina; Rippke, Frank; Schoelermann, Andrea M.; Filbry, Alexander W.

    2012-01-01

    Objective: To assess the effects of Light Formulation, an oil-in-water emulsion, and Rich Formulation, a water-in-oil emulsion, for the treatment of xerosis. Design: Two double-blind, vehicle-controlled trials (both formulations); a double-blind, randomized regression study (Rich Formulation); and a single-blind tolerability study (Light Formulation). The two formulations were applied twice daily for two weeks, for five days in the regression study, and twice daily for two weeks in the tolerability study. Setting: Studies were conducted during winter in Hamburg, Germany. Participants: A total of 169 subjects were enrolled and 154 completed the studies. The majority were between 50 and 80 years of age, women, all with very dry skin. One withdrew because of an incompatibility reaction that reoccurred with the subject's own body lotion after sun exposure. Measurements: Skin hydration and skin barrier function with both formulations over two weeks, long-term moisturization effect after discontinuation of Rich Formulation, and symptom improvement and skin tolerability with Light Formulation. Results: Vehicle-controlled studies of Light and Rich Formulations demonstrated significantly improved hydration at Weeks 1 and 2 versus the untreated site and vehicles, and significantly reduced transepidermal water loss versus untreated site and basic vehicle. Both products significantly decreased visible dryness and tactile roughness. In the regression study, Rich Formulation maintained significant moisturization six days after treatment discontinuation. Light Formulation reduced symptoms of itching, burning, tightness, tingling, and feeling of dryness. Conclusion: These formulations represent a new approach for the treatment of xerosis by addressing multiple key deficiencies in skin hydration. PMID:22916312

  3. In-vivo evaluation of clindamycin release from glyceryl monooleate-alginate microspheres by NIR spectroscopy.

    PubMed

    Mohamed, Amir Ibrahim; Ahmed, Osama A A; Amin, Suzan; Elkadi, Omar Anwar; Kassem, Mohamed A

    2015-10-15

    The purpose of this study was to use near-infrared (NIR) transmission spectroscopic technique to determine clindamycin plasma concentration after oral administration of clindamycin loaded GMO-alginate microspheres using rabbits as animal models. Lyophilized clindamycin-plasma standard samples at a concentration range of 0.001-10 μg/ml were prepared and analyzed by NIR and HPLC as a reference method. NIR calibration model was developed with partial least square (PLS) regression analysis. Then, a single dose in-vivo evaluation was carried out and clindamycin-plasma concentration was estimated by NIR. Over 24 h time period, the pharmacokinetic parameters of clindamycin were calculated for the clindamycin loaded GMO-alginate microspheres (F3) and alginate microspheres (F2), and compared with the plain drug (F1). PLS calibration model with 7-principal components (PC), and 8000-9200 cm(-1) spectral range shows a good correlation between HPLC and NIR values with root mean square error of cross validation (RMSECV), root mean square error of prediction (RMSEP), and calibration coefficient (R(2)) values of 0.245, 1.164, and 0.9753, respectively, which suggests that NIR transmission technique can be used for drug-plasma analysis without any extraction procedure. F3 microspheres exhibited controlled and prolonged absorption Tmax of 4.0 vs. 1.0 and 0.5 h; Cmax of 2.37±0.3 vs. 3.81±0.8 and 5.43±0.7 μg/ml for F2 and F1, respectively. These results suggest that the combination of GMO and alginate (1:4 w/w) could be successfully employed for once daily clindamycin microspheres formulation which confirmed by low Cmax and high Tmax values.

  4. A safety trial of high dose glyceryl triacetate for Canavan disease.

    PubMed

    Segel, Reeval; Anikster, Yair; Zevin, Shoshana; Steinberg, Avraham; Gahl, William A; Fisher, Drora; Staretz-Chacham, Orna; Zimran, Ari; Altarescu, Gheona

    2011-07-01

    Canavan disease (CD MIM#271900) is a rare autosomal recessive neurodegenerative disorder presenting in early infancy. The course of the disease is variable, but it is always fatal. CD is caused by mutations in the ASPA gene, which codes for the enzyme aspartoacylase (ASPA), which breaks down N-acetylaspartate (NAA) to acetate and aspartic acid. The lack of NAA-degrading enzyme activity leads to excess accumulation of NAA in the brain and deficiency of acetate, which is necessary for myelin lipid synthesis. Glyceryltriacetate (GTA) is a short-chain triglyceride with three acetate moieties on a glycerol backbone and has proven an effective acetate precursor. Intragastric administration of GTA to tremor mice results in greatly increased brain acetate levels, and improved motor functions. GTA given to infants with CD at a low dose (up to 0.25 g/kg/d) resulted in no improvement in their clinical status, but also no detectable toxicity. We present for the first time the safety profile of high dose GTA (4.5 g/kg/d) in 2 patients with CD. We treated 2 infants with CD at ages 8 months and 1 year with high dose GTA, for 4.5 and 6 months respectively. No significant side effects and no toxicity were observed. Although the treatment resulted in no motor improvement, it was well tolerated. The lack of clinical improvement might be explained mainly by the late onset of treatment, when significant brain damage was already present. Further larger studies of CD patients below age 3 months are required in order to test the long-term efficacy of this drug.

  5. Synthesis and antitumor activity of new alkylphospholipids containing modifications of the phosphocholine moiety.

    PubMed

    Ukawa, K; Imamiya, E; Yamamoto, H; Mizuno, K; Tasaka, A; Terashita, Z; Okutani, T; Nomura, H; Kasukabe, T; Hozumi, M

    1989-05-01

    New antitumor alkylglycerophospholipids, in which primarily the phosphocholine moiety of the platelet activating factor (PAF) molecule was modified, were synthesized from 1-alkyl-2-substituted glycerols by introducing polar head phosphoryl groups having methylene bridges of various lengths (from 2 to 14 carbons). They were tested for PAF agonistic activity and antitumor properties. In a series of 1-octadecyl-2-acetoacetylglycerophospholipids (1a-f), an increase in the length of the methylene bridge separating the phosphate and trimethylammonio group in the polar head side chain at position 3 of the glycerol backbone resulted in a progressive decrease in PAF agonistic activity and a characteristic change in antitumor activity against human promyelocytic leukemia cells (HL-60). Maximal potency was obtained with the compound having a decamethylene bridge (1e, IC50 value = 1.5 microgram/ml). Thus, alkylphospholipids possessing a decamethylene bridge and a variety of substituents at position 2 (1g-n) were synthesized. They showed potent inhibitory activity with IC50 values ranging from 0.4 to 1.9 micrograms/ml, depending on the nature of the 2-substituent in the phospholipid molecule. In in vivo tests of the present series of alkylglycerophospholipids (1a--n), using mice bearing sarcoma 180 and mice with mammary carcinoma MM46 (both cells and compounds were given i.p.), 1-octadecyl-2-acetoacetyl-3-glyceryl omega-trimethylammoniodecyl phosphate (1e) showed the most potent life-prolonging effect. The structure-activity relationships are discussed.

  6. Enhanced topical delivery of finasteride using glyceryl monooleate-based liquid crystalline nanoparticles stabilized by cremophor surfactants.

    PubMed

    Madheswaran, Thiagarajan; Baskaran, Rengarajan; Yong, Chul Soon; Yoo, Bong Kyu

    2014-02-01

    The aim of this study was to investigate the capability of two surfactants, Cremophor RH 40 (RH) and Cremophor EL (EL), to prepare liquid crystalline nanoparticles (LCN) and to study its influence on the topical delivery of finasteride (FNS). FNS-loaded LCN was formulated with the two surfactants and characterized for size distribution, morphology, entrapment efficiency, in vitro drug release, and skin permeation/retention. Influence of FNS-loaded LCN on the conformational changes on porcine skin was also studied using attenuated total reflectance Fourier-transform infrared spectroscopy. Transmission electron microscopical image confirmed the formation of LCN. The average particle size of formulations was in the range of 165.1-208.6 and 153.7-243.0 nm, respectively. The formulations prepared with higher surfactant concentrations showed faster release and significantly increased skin permeation. Specifically, LCN prepared with RH 2.5% presented higher permeation flux (0.100 ± 0.005 μgcm(-2)h(-1)) compared with lower concentration (0.029 ± 0.007 μgcm(-2)h(-1)). Typical spectral bands of lipid matrix of porcine skin were shifted to higher wavenumber, indicating increased degree of disorder of the lipid acyl chains which might cause fluidity increase of stratum corneum. Taken together, Cremophor surfactants exhibited a promising potential to stabilize the LCN and significantly augmented the skin permeation of FNS.

  7. 1-O-alkenyl-sn-glyceryl-3-phosphorylcholine may be a novel posttranslational modification used by the placenta.

    PubMed

    Lowry, Philip

    2011-01-01

    Neurokinin B (NKB) secreted by the placenta was previously found to be raised in preeclampsia and most of the symptoms in this disease appeared to be through progressive activation of the three neurokinin receptors. Further characterization of placental NKB revealed that placental NKB eluted in the approximate position of a 13mer and this was confirmed by TOF mass spectrometry which gave a mass of 1580. Although this is consistent with dimethylated NKB-Gly-Lys-Arg, further characterization (immunological and mass spectrometric fragment analysis) suggested a novel posttranslational modification containing phosphocholine (PC) with some evidence for glycerol and a coordinated alkene. The structure that fits all the data is that a form of platelet activating factor is attached to the aspartyl side chain at position 4 of NKB and thus now implicates placental NKB in the platelet pathology seen in preeclampsia. As it has been reported that it is the PC group per se attached to certain proteins secreted by filarial nematodes imparts them with immune inhibitory properties and thus survival in the host over long periods, attaching PC to placental secretory peptide hormones (also be found on the placental precursors of CRF, ACTH, and activin) may result in a similar situation.

  8. Effect of ethylcellulose and propylene glycol on the controlled-release performance of glyceryl monooleate-mertronidazole periodontal gel.

    PubMed

    Sallam, Al-Sayed; Hamudi, Firas Falih; Khalil, Enam Ayoub

    2015-03-01

    Controlled-release metronidazole, mucoadhesive gel proposed as a drug-delivery system for periodontal application was developed and characterized. The system was based on a mixture of glycerylmonooleate (GMO) and ethylcellulose (EC). The mechanism of release depends: firstly, on the ability of GMO to form a viscous liquid crystalline mesophases and secondly on the solubilized EC to form a hydrophobic network when the mixture comes into contact with water resulting in sustaining the release of the drug. Ethylcellulose dissolved in GMO had a profound influence on the rate of drug release, reduced the initial drug release and prolonged the sustained release of metronidazole. Propylene glycol (PG) was added to increase the solubility of the drug and water was added with PG to control the viscosity. A controlled release formulation containing w/w, 20% metronidazole, 10% PG, 5% water and 65% GMO that contains 7% EC was found to be mucoadhesive, easily injectable at room temperature, and to follow Fickian diffusion release mechanism. When the drug loading was increased the drug release was accelerated, and the mechanism followed anomalous controlled-release mechanism. Stability studies indicated that the formulation should be stored at 4 °C in a dark place.

  9. Advanced Design Linear Noise-Attenuating Earphone-Earcup System.

    DTIC Science & Technology

    1981-08-01

    contains water, glycerin , glycol, stearate, beeswax, lanolin oil, sesame oil, glyceryl oleate, glyceryl stearate, isopropyl myristate, myristyl...myristate, stearett-2, triethonolamine, sodium glyceryl oleate phosphate, carbomer-940 fragrance , formaldehyde, FD & CY yellow #5. -23- DIRECTIONAL STIFFNESS

  10. Liquid Crystalline Nanoparticles as an Ophthalmic Delivery System for Tetrandrine: Development, Characterization, and In Vitro and In Vivo Evaluation

    NASA Astrophysics Data System (ADS)

    Liu, Rui; Wang, Shuangshuang; Fang, Shiming; Wang, Jialu; Chen, Jingjing; Huang, Xingguo; He, Xin; Liu, Changxiao

    2016-05-01

    The purpose of this study was to develop novel liquid crystalline nanoparticles (LCNPs) that display improved pre-ocular residence time and ocular bioavailability and that can be used as an ophthalmic delivery system for tetrandrine (TET). The delivery system consisted of three primary components, including glyceryl monoolein, poloxamer 407, and water, and two secondary components, including Gelucire 44/14 and amphipathic octadecyl-quaternized carboxymethyl chitosan. The amount of TET, the amount of glyceryl monoolein, and the ratio of poloxamer 407 to glyceryl monoolein were selected as the factors that were used to optimize the dependent variables, which included encapsulation efficiency and drug loading. A three-factor, five-level central composite design was constructed to optimize the formulation. TET-loaded LCNPs (TET-LCNPs) were characterized to determine their particle size, zeta potential, entrapment efficiency, drug loading capacity, particle morphology, inner crystalline structure, and in vitro drug release profile. Corneal permeation in excised rabbit corneas was evaluated. Pre-ocular retention was determined using a noninvasive fluorescence imaging system. Finally, pharmacokinetic study in the aqueous humor was performed by microdialysis technique. The optimal formulation had a mean particle size of 170.0 ± 13.34 nm, a homogeneous distribution with polydispersity index of 0.166 ± 0.02, a positive surface charge with a zeta potential of 29.3 ± 1.25 mV, a high entrapment efficiency of 95.46 ± 4.13 %, and a drug loading rate of 1.63 ± 0.07 %. Transmission electron microscopy showed spherical particles that had smooth surfaces. Small-angle X-ray scattering profiles revealed an inverted hexagonal phase. The in vitro release assays showed a sustained drug release profile. A corneal permeation study showed that the apparent permeability coefficient of the optimal formulation was 2.03-fold higher than that of the TET solution. Pre-ocular retention

  11. Activation of the human neutrophil respiratory burst with zymosan-activated serum.

    PubMed

    Smith, R J; Iden, S S; Bowman, B J

    1984-06-15

    Zymosan-activated serum ( ZAS ) stimulated a time- and concentration-dependent generation of superoxide anion (O-2) by human neutrophils. O-2 production was rapid with maximum generation occurring 2 minutes after cell exposure to ZAS . O-2 generation is markedly reduced if cells are not preincubated with cytochalasin B prior to contact with ZAS . The amount of O-2 produced by ZAS stimulated neutrophils was enhanced in the presence of extra-cellular calcium. However, the intracellular calcium antagonist, 8-(N,N-diethylamino)-octyl-(3,4,5-trimethoxy) benzoate hydrochloride (TMB-8), caused a dose-related inhibition of ZAS -elicited O-2 production. Neutrophils pretreated with ZAS were desensitized to the subsequent exposure to this stimulus. The fact that pretreatment of neutrophils with ZAS did not diminish the capacity of these cells to generate O-2 in response to 1-O-hexadecyl/octadecyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine (AGEPC),N-formyl-methionyl-leucyl-phenylalanine (FMLP) or 5(5),12(R)-dihydroxy-6,14-cis-8,10-trans-eicosatetraenoic acid (LTB4), demonstrates the stimulus specific nature of ZAS -induced desensitization. Thus, ZAS , which contains the complement-derived neutrophil activator, C5a, a naturally occurring phlogistic mediator, represents a relevant probe for investigating neutrophil function.

  12. Stable isotope-assisted LC-MS/MS monitoring of glyceryl trinitrate bioactivation in a cell culture model of nitrate tolerance.

    PubMed

    Axton, Elizabeth R; Hardardt, Elizabeth A; Stevens, Jan F

    2016-04-15

    The nitric oxide (NO) metabolites nitrite (NO2(-)) and nitrate (NO3(-)) can be quantified as an endpoint of endothelial function. We developed a LC-MS/MS method of measuring nitrite and nitrate isotopologues, which has a lower limit of quantification (LLOQ) of 1 nM. This method allows for isotopic labeling to differentiate newly formed nitrite and nitrate from nanomolar to micromolar background levels of nitrite and nitrate in biological matrices. This method utilizes 2,3-diaminonaphthalene (DAN) derivatization, which reacts with nitrite under acidic conditions to produce 2,3-naphthotriazole (NAT). NAT was chromatographically separated on a Shimadzu LC System with an Agilent Extend-C18 5 μm 2.1 × 150 mm column and detected using a multiple reaction monitoring (MRM) method on an ABSciex 3200 QTRAP mass spectrometer operated in positive mode. Mass spectrometry allows for the quantification of (14)N-NAT (m/z 170.1) and (15)N-NAT (m/z 171.1). Both nitrite and nitrate demonstrated a linear detector response (1 nM - 10 μM, 1 nM - 100 nM, respectively), and were unaffected by common interferences (Dulbecco's Modified Eagle Medium (DMEM), fetal bovine serum (FBS), phenol red, and NADPH). This method requires minimal sample preparation, making it ideal for most biological applications. We applied this method to develop a cell culture model to study the development of nitrate tolerance in human endothelial cells (EA.hy926).

  13. Impact of the post-treatment conditions of parent silica on the silanization of n-octadecyl bonded silica packings in reversed-phase high-performance liquid chromatography.

    PubMed

    Grossmann, F; Ehwald, V; du Fresne von Hohenesche, C; Unger, K K

    2001-03-02

    Native mesoporous silica beads were subjected to a sequence of post-treatment procedure including hydrochloric acid treatment, calcination and subsequent rehydroxylation. The post-treated silica beads were converted into RP-18 silica by silanization with monochloro- and dimethoxy-n-octadecylsilanes, respectively. The influence of post-treatments and silanization conditions on the physico-chemical characteristics and on the chromatographic behaviour of the RP-silicas was studied. Also the changes of the pore structural parameters and the silanol group densities during the post-treatment and silanization were assessed.

  14. Fabrication and spectroscopic characterization of Langmuir-Blodgett films with luminescent rare earth complexes of long chain double functional ligands mono-L phthalate (L = hexadecyl, octadecyl and eicosyl).

    PubMed

    Yan, Bing; Xu, Bing

    2009-07-01

    In this paper, some novel long chain amphiphillic monoester molecules were designed to afford double functions: film-formation ability and luminescent sensitization ability. Subsequently organized molecular films of rare earth complexes with these functional ligands formulated as ML2NO3 were fabricated by the Langmuir-Blodgett film (LB) technology, where RE denotes rare earth ions Eu3+, Tb3+ and Dy3+; L denotes the long chain carboxylic ligands monohexadecyl phthalate (16-Phth), monooctadecyl phthalate (18-Phth) and monoeicosyl phthalate (20-Phth). The average molecular area was obtained according to the pi-A isotherms. The layer structure of the LB films was demonstrated by low-angle X-ray diffraction and the average layer spacing was determined from the Bragg equation. UV absorption intensity increases linearly with the number of LB films layers, which indicates that the LB films are homogeneously deposited. The fluorescence spectra of these LB films were quite different from those of their solid complexes. It reveals that the long chain ester ligands are suitable for the excited states of Tb3+ and Dy3+ in the LB films as well as in the solid complexes, but not match with the europium ion in the LB films.

  15. Solid-phase extraction of polar pesticides from environmental water samples on graphitized carbon and Empore-activated carbon disks and on-line coupling to octadecyl-bonded silica analytical columns.

    PubMed

    Slobodník, J; Oztezkizan, O; Lingeman, H; Brinkman, U A

    1996-10-25

    The suitability of Empore-activated carbon disks (EACD), Envi-Carb graphitized carbon black (GCB) and CPP-50 graphitized carbon for the trace enrichment of polar pesticides from water samples was studied by means of off-line and on-line solid-phase extraction (SPE). In the off-line procedure, 0.5-2 l samples spiked with a test mixture of oxamyl, methomyl and aldicarb sulfoxide were enriched on EnviCarb SPE cartridges or 47 mm diameter EACD and eluted with dichloromethane-methanol. After evaporation, a sample was injected onto a C18-bonded silica column and analysed by liquid chromatography with ultraviolet (LC-UV) detection. EACD performed better than EnviCarb cartridges in terms of breakthrough volumes (> 2 l for all test analytes), reproducibility (R.S.D. of recoveries, 4-8%, n = 3) and sampling speed (100 ml/min); detection limits in drinking water were 0.05-0.16 microgram/l. In the on-line experiments, 4.6 mm diameter pieces cut from original EACD and stacked onto each other in a 9 mm long precolumn, and EnviCarb and CPP-50 packed in 10 x 2.0 mm I.D. precolumn, were tested, and 50-200 ml spiked water samples were preconcentrated. Because of the peak broadening caused by the strong sorption of the analytes on carbon, the carbon-packed precolumns were eluted by a separate stream of 0.1 ml/min acetonitrile which was mixed with the gradient LC eluent in front of the C18 analytical column. The final on-line procedure was also applied for the less polar propoxur, carbaryl and methiocarb. EnviCarb could not be used due to its poor pressure resistance. CPP-50 provided less peak broadening than EACD: peak widths were 0.1-0.3 min and R.S.D. of peak heights 4-14% (n = 3). In terms of analyte trapping efficiency on-line SPE-LC-UV with a CPP-50 precolumn also showed better performance than when Bondesil C18/OH or polymeric PLRP-S was used, but chromatographic resolution was similar. With the CPP-50-based system, detection limits of the test compounds were 0.05-1 microgram/l in surface water.

  16. Final report on the safety assessment of Glycyrrhetinic Acid, Potassium Glycyrrhetinate, Disodium Succinoyl Glycyrrhetinate, Glyceryl Glycyrrhetinate, Glycyrrhetinyl Stearate, Stearyl Glycyrrhetinate, Glycyrrhizic Acid, Ammonium Glycyrrhizate, Dipotassium Glycyrrhizate, Disodium Glycyrrhizate, Trisodium Glycyrrhizate, Methyl Glycyrrhizate, and Potassium Glycyrrhizinate.

    PubMed

    2007-01-01

    Glycyrrhetinic Acid and its salts and esters and Glycyrrhizic Acid and its salts and esters are cosmetic ingredients that function as flavoring agents or skin-conditioning agents - miscellaneous or both. These chemicals may be isolated from licorice plants. Glycyrrhetinc Acid is described as at least 98% pure, with 0.6% 24-OH-Glycyrrhetinic Acid, not more than 20 mu g/g of heavy metals and not more than 2 mu g/g of arsenic. Ammonium Glycyrrhizate has been found to be at least 98% pure and Dipotassium Glycyrrhizate has been found to be at least 95% pure. Glycyrrhetinic Acid is used in cosmetics at concentrations of up to 2%; Stearyl Glycyrrhetinate, up to 1%; Glycyrrhizic Acid, up to 0.1%; Ammonium Glycyrrhizate, up to 5%; Dipotassium Glycyrrhizate, up to 1%; and Potassium Glycyrretinate, up to 1%. Although Glycyrrhizic Acid is poorly absorbed by the intestinal tract, it may be hydrolyzed to Glycyrrhetinic Acid by a beta -glucuronidase produced by intestinal bacteria. Glycyrrhetinic Acid and Glycyrrhizic Acid bind to rat and human albumin, but do not absorb well into tissues. Glycyrrhetinic Acid and Glycyrrhizic Acid and metabolites are mostly excreted in the bile, with very little excreted in urine. Dipotassium Glycyrrhizate was undetectable in the receptor chamber when tested for transepidermal permeation through pig skin. Glycyrrhizic Acid increased the dermal penetration of diclofenac sodium in rat skin. Dipotassium Glycyrrhizate increased the intestinal absorption of calcitonin in rats. In humans, Glycyrrhetinic Acid potentiated the effects of hydrocortisone in the skin. Moderate chronic or high acute exposure to Glycyrrhizic Acid, Ammonium Glycyrrhizate, and their metabolites have been demonstrated to cause transient systemic alterations, including increased potassium excretion, sodium and water retention, body weight gain, alkalosis, suppression of the renin-angiotensis-aldosterone system, hypertension, and muscular paralysis; possibly through inhibition of 11beta -hydroxysteroid dehydrogenase-2 (11beta -OHSD2) in the kidney. Glycyrrhetinic Acid and its derivatives block gap junction intracellular communication in a dose-dependent manner in animal and human cells, including epithelial cells, fibroblasts, osteoblasts, hepatocytes, and astrocytes; at high concentrations, it is cytotoxic. Glycyrrhetinic Acid and Glycyrrhizic Acid protect liver tissue from carbon tetrachloride. Glycyrrhizic Acid has been used to treat chronic hepatitis, inhibiting the penetration of the hepatitis A virus into hepatocytes. Glycyrrhetinic Acid and Glycyrrhizic Acid have anti-inflammatory effects in rats and mice. The acute intraperitoneal LD(50) for Glycyrrhetinic Acid in mice was 308 mg/kg and the oral LD(50) was > 610 mg/kg. The oral LD(50) in rats was reported to be 610 mg/kg. Higher LD(50) values were generally reported for salts. Little short-term, subchronic, or chronic toxicity was seen in rats given ammonium, dipotassium, or disodium salts of Glycyrrhizic Acid. Glycyrrhetinic Acid was not irritating to shaved rabbit skin, but was considered slightly irritating in an in vitro test. Glycyrrhetinic Acid inhibited the mutagenic activity of benzo[a]pyrene and inhibited tumor initiation and promotion by other agents in mice. Glycyrrhizic Acid inhibited tumor initiation by another agent, but did not prevent tumor promotion in mice. Glycyrrhizic Acid delayed mortality in mice injected with Erlich ascites tumor cells, but did not reduce the mortality rate. Ammonium Glycyrrhizate was not genotoxic in in vivo and in vitro cytogenetics assays, the dominant lethal assay, an Ames assay, and heritable translocation tests, except for possible increase in dominant lethal mutations in rats given 2000 mg/kg day(-1) in their diet. Disodium Glycyrrhizate was not carcinogenic in mice in a drinking water study at exposure levels up to 12.2 mg/kg day(-1) for 96 weeks. Glycyrrhizate salts produced no reproductive or developmental toxicity in rats, mice, golden hamsters, or Dutch-belted rabbits, except for a dose-dependent increase (at 238.8 and 679.9 mg/kg day(-1)) in sternebral variants in a study using rats. Sedation, hypnosis, hypothermia, and respiratory depression were seen in mice given 1250 mg/kg Glycyrrhetinic Acid intraperitoneally. Rats fed a powdered diet containing up to 4% Ammonium Glycyrrhizate had no treatment related effects in motor function tests, but active avoidance was facilitated at 4%, unaffected at 3%, and depressed at 2%. In a study of 39 healthy volunteers, a no effect level of 2 mg/kg/day was determined for Glycyrrhizic Acid given orally for 8 weeks. Clinical tests in seven normal individuals given oral Ammonium Glycyrrhizate at 6 g/day for 3 days revealed reduced renal and thermal sweat excretion of Na+ and K+, but carbohydrate and protein metabolism were not affected. Glycyrrhetinic Acid at concentrations up to 6% was not a skin irritant or a sensitizer in clinical tests. Neither Glycyrrhizic Acid, Ammonium Glycyrrhizate, nor Dipotassium Glycyrrhizate at 5% were phototoxic agents or photosensitizers. Birth weight and maternal blood pressure were unrelated to the level of consumption of Glycyrrhizic Acid in 1049 Finnish women with infants, but babies whose mother consumed > 500 mg/wk were more likely to be born before 38 weeks. The Cosmetic Ingredient Review (CIR) Expert Panel noted that the ingredients in this safety assessment are not plant extracts, powders, or juices, but rather are specific chemical species that may be isolated from the licorice plant. Because these chemicals may be isolated from plant sources, however, steps should be taken to assure that pesticide and toxic metal residues are below acceptable levels. The Panel advised the industry that total polychlorobiphenyl (PCB)/pesticide contamination should be limited to not more than 40 ppm, with not more than 10 ppm for any specific residue, and that toxic metal levels must not contain more than 3 mg/kg of arsenic (as As), not more than 0.002% heavy metals, and not more than 1 mg/kg of lead (as Pb). Although the Panel noted that Glycyrrhizic Acid is cytotoxic at high doses and ingestion can have physiological effects, there is little acute, short-term, subchronic, or chronic toxicity and it is expected that these ingredients would be poorly absorbed through the skin. These ingredients are not considered to be irritants, sensitizers, phototoxic agents, or photosensitizers at the current maximum concentration of use. Accordingly, the CIR Expert Panel concluded that these ingredients are safe in the current practices of use and concentration. The Panel recognizes that certain ingredients in this group are reportedly used in a given product category, but the concentration of use is not available. For other ingredients in this group, information regarding use concentration for specific product categories is provided, but the number of such products is not known. In still other cases, an ingredient is not in current use, but may be used in the future. Although there are gaps in knowledge about product use, the overall information available on the types of products in which these ingredients are used and at what concentration indicate a pattern of use. Within this overall pattern of use, the Expert Panel considers all ingredients in this group to be safe.

  17. 40 CFR 180.920 - Inert ingredients used pre-harvest; exemptions from the requirement of a tolerance.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    .../stabilizer Boric acid Sequestrant Buffalo gourd root powder (Cucurbita foetidissima root powder); or.... 31075-24-8) For use in pesticide formulations applied to cotton or wheat only Adjuvant or water... water-soluble film Glyceryl triacetate Stabilizer Glyceryl tris-12-hydroxystearate Flow control...

  18. 21 CFR 172.832 - Monoglyceride citrate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN... glyceryl monooleate and its citric acid monoester manufactured by the reaction of glyceryl monooleate with... addition to oils and fats whereby the additive does not exceed 200 parts per million of the combined...

  19. Solid lipid extrusion of sustained release dosage forms.

    PubMed

    Reitz, Claudia; Kleinebudde, Peter

    2007-09-01

    The applicability of the solid lipid extrusion process as preparations method for sustained release dosage forms was investigated in this study. Two lipids with similar melting ranges but of different composition, glyceryl palmitostearate (Precirol ATO 5) and glyceryl trimyristate (Dynasan 114), and mixtures of each lipid with 50% or 75% theophylline were extruded at temperatures below their melting ranges. Extrudates were analyzed using differential scanning calorimetry, scanning electron microscopy, porosity measurements and in vitro drug dissolution studies. The possibility of processing lipids by softening instead of complete melting and without subsequent formation of low-melting, metastable polymorphs could be demonstrated. Extrudates based on formulations of glyceryl palmitostearate/theophylline (50:50) and glyceryl trimyristate/theophylline (50:50) showed sustained release properties. An influence of extrusion conditions on the matrix structure was shown for extrudates based on a mixture of glyceryl trimyristate and theophylline (50:50). Glyceryl trimyristate tended to solidify in porous structures after melting. Exceeding a material temperature of 50.5 degrees C led to porous extrudate matrices with a faster drug release. The production of novel, non porous sustained release matrices was possible at a material temperature of 49.5 degrees C. Extrudates based on glyceryl trimyristate/theophylline (50:50) only slight changes in melting enthalpy and stable drug release profiles.

  20. 21 CFR 178.3860 - Release agents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... of octadecyl isocyanate and vinyl alcohol/vinyl acetate copolymer; minimum average molecular weight.... Saturated fatty acid amides manufactured from fatty acids derived from animal, marine, or vegetable fats...

  1. 21 CFR 178.3860 - Release agents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... of octadecyl isocyanate and vinyl alcohol/vinyl acetate copolymer; minimum average molecular weight.... Saturated fatty acid amides manufactured from fatty acids derived from animal, marine, or vegetable fats...

  2. Lipstick dermatitis due to C18 aliphatic compounds.

    PubMed

    Hayakawa, R; Matsunaga, K; Suzuki, M; Arima, Y; Ohkido, Y

    1987-04-01

    An 18-year-old girl developed cheilitis. She had a past history of lip cream dermatitis, but the cause was not found. Patch tests with 2 lipsticks were strongly positive. Tests with the ingredients were positive to 2 aliphatic compounds, glyceryl diisostearate and diisostearyl malate. Impurities in the materials were suspected as the cause. Analysis by gas chromatography detected 3 chemicals in glyceryl diisostearate and 1 in diisostearyl malate as impurities. Patch testing with the impurities and glyceryl monoisostearate 0.01% pet in glyceryl diisostearate and isostearyl alcohol 0.25% pet in diisostearyl malate were strongly positive. The characteristics common to the 2 chemicals were liquidity at room temperature, branched C18 aliphatic compound and primary alcohol. Chemicals lacking any of the above 3 features did not react.

  3. Comparative study of the antioxidant activities of some lipase-catalyzed alkyl dihydrocaffeates synthesized in ionic liquid.

    PubMed

    Gholivand, Somayeh; Lasekan, Ola; Tan, Chin Ping; Abas, Faridah; Wei, Leong Sze

    2017-06-01

    The solubility limitations of phenolic acids in many lipidic environments are now greatly improved by their enzymatic esterification in ionic liquids (ILs). Herein, four different ILs were tested for the esterification of dihydrocaffeic acid with hexanol and the best IL was selected for the synthesis of four other n-alkyl esters with different chain-lengths. The effect of alkyl chain length on the anti-oxidative properties of the resulted purified esters was investigated using β-carotene bleaching (BCB) and free radical scavenging method DPPH and compared with butylated hydroxytoluene (BHT) as reference compound. All four esters (methyl, hexyl, dodecyl and octadecyl dihydrocaffeates) exhibited relatively strong radical scavenging abilities. The scavenging activity of the test compounds was in the following order: methyl ester>hexyl ester⩾dodecyl ester>octadecyl ester>BHT while the order for the BCB anti-oxidative activity was; BHT>octadecyl ester>dodecyl ester>hexyl ester>methyl ester.

  4. Effect of the physicochemical parameters of benzimidazole molecules on their retention by a nonpolar sorbent from an aqueous acetonitrile solution

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Safonova, I. A.; Bulanova, A. V.

    2015-09-01

    The effect of the structure of benzimidazoles on their chromatographic retention on octadecyl silica gel from an aqueous acetonitrile eluent was studied. One- and many-parameter correlation equations were obtained by linear regression analysis, and their prognostic potential in determining the retention factors of benzimidazoles under study was analyzed.

  5. Sorption of catechins under conditions of reverse-phase high-efficiency liquid chromatography

    NASA Astrophysics Data System (ADS)

    Shafigulin, R. V.; Egorova, K. V.; Bulanova, A. V.

    2010-08-01

    The physico-chemical principles of catechin sorption from various polar solvents onto silica gel modified with octadecyl groups were studied. Thermodynamic characteristics of the sorption were calculated, and the applicability of different models of retention was demonstrated for catechins under the conditions of reverse-phase high-efficiency liquid chromatography.

  6. Effects of nanoclay type on the physical and antimicrobial properties of PVOH-based nanocomposite films

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Polyvinyl alcohols-based nanocomposite films were fabricated with four types of montmorillonite (MMT) nanoclay, including 18-amino stearic acid (I.24TL), methyl, bis hydroxyethyl, octadecyl ammonium (I.34TCN), di-methyl, di-hydrogenated tallow ammonium/siloxane (I.44PSS) organically modified MMT, an...

  7. The capture and stabilization of curcumin using hydrophobically modified polyacrylate aggregates and hydrogels.

    PubMed

    Harada, Takaaki; Pham, Duc-Truc; Lincoln, Stephen F; Kee, Tak W

    2014-08-07

    Hydrophobically modified polyacrylates are shown to suppress the degradation of the medicinal pigment curcumin under physiological conditions. In aqueous solution, the 3% octadecyl randomly substituted polyacrylate, PAAC18, forms micelle-like aggregates at a concentration of <1 wt % and a hydrogel at >1 wt %. Under both conditions, PAAC18 shows a remarkable ability to suppress the degradation of curcumin at pH 7.4 and 37 °C such that its degradation half-life is increased by 1600-2000-fold. The suppression of degradation is attributed to hydrophobic interactions between curcumin and the octadecyl substituents of PAAC18 within the micelle-like aggregates and the hydrogel, as indicated by 2D NOESY (1)H NMR spectroscopy. UV-visible absorption titration results are consistent with the interaction of curcumin with five octadecyl substituents on average, which appears to substantially exclude water and greatly decrease the curcumin degradation rate. Dynamic light scattering and zeta potential measurements show the average hydrodynamic diameters of the PAAC18 aggregates to be 0.86-1.15 μm with a negative surface charge. In contrast to the octadecyl substitution, the 3% dodecyl randomly substituted polyacrylate, PAAC12, shows a negligible effect on slowing the degradation of curcumin, consistent with the dodecyl substituents being insufficiently long to capture curcumin in a adequately hydrophobic environment. These observations indicate the potential for PAAC18 to act as a model drug delivery system.

  8. DOPC liposomes doped with octadecylferulate

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Octadecyl ferulate, found in limit quantities in plants, is a natural phenolic derivative with the potential as a cosmeceautical, nutriceutical, and/or pharmaceutical ingredient because of its lipophilic and antioxidant properties. The current work demonstrates our ability to chemically synthesize a...

  9. Thermal characteristics of oleochemical carbonate binary mixtures for potential latent heat storage

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The present study examines the thermal properties of melting and solidification for binary mixtures between dodecyl carbonate (1a), tetradecyl carbonate (1b), hexadecyl carbonate (1c), and octadecyl carbonate (1d) by differential scanning calorimetry (DSC) in order to gain further understanding of t...

  10. Assessing the Toxicity and Bioavailability of 2,4-Dinitroanisole in Acute and Sub-Chronic Exposures Using the Earthworm, Eisenia fetida

    DTIC Science & Technology

    2010-06-01

    different methods, 2nd method chosen for final study: ► Coelomocytes collected in 2 ml Guaiacol Glyceryl Ether ( GGE ) solution, centrifuged, decanted...worm to GGE t= 2mins collect coelomocyte solution 1 row per worm/treatment, obtain measurements through spectrophotometer NRRT analysis 1) 2) BUILDING

  11. 21 CFR 172.665 - Gellan gum.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ....50 gram of sodium chloride is added. The solution is heated to 80 °C with stirring, held at 80 °C for..., sodium, calcium, and magnesium salt. The polysaccharide may contain acyl (glyceryl and acetyl) groups as... bore pipet and transferred into a solution of 10-percent calcium chloride. A tough worm-like gel...

  12. 21 CFR 172.832 - Monoglyceride citrate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION... monooleate and its citric acid monoester manufactured by the reaction of glyceryl monooleate with citric acid... percent-17 percent. (b) It is used, or intended for use, in antioxidant formulations for addition to...

  13. 21 CFR 172.832 - Monoglyceride citrate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Multipurpose Additives § 172.832... manufactured by the reaction of glyceryl monooleate with citric acid under controlled conditions may be safely... use, in antioxidant formulations for addition to oils and fats whereby the additive does not...

  14. 21 CFR 184.1903 - Tributyrin.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Substances Affirmed as GRAS § 184.1903 Tributyrin. (a) Tributyrin (C15H26O6, CAS Reg. No. 60-01-5), also known as butyrin or glyceryl tributyrate, is the triester of glycerin and butyric acid. It is prepared by esterification of glycerin with excess butyric acid. (b) The ingredient meets the specification...

  15. 21 CFR 184.1903 - Tributyrin.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Substances Affirmed as GRAS § 184.1903 Tributyrin. (a) Tributyrin (C15H26O6, CAS Reg. No. 60-01-5), also known as butyrin or glyceryl tributyrate, is the triester of glycerin and butyric acid. It is prepared by esterification of glycerin with excess butyric acid. (b) The ingredient meets the specification...

  16. Investigations into the chemistry and insecticidal activity of euonymus europaeus seed oil and methanol extract

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Euonymus europaeus seeds and seed oil were investigated for their volatiles using GC-MS-FID, Headspace-SPME/GC-MS-FID, and derivative GC-MS-FID for their volatiles and HPLC-DAD-CAD/MS for their non-volatile compounds. The seeds contain about 30% of fatty oil, mainly glyceryl trioleate, small amounts...

  17. Rifabutin-loaded solid lipid nanoparticles for inhaled antitubercular therapy: Physicochemical and in vitro studies.

    PubMed

    Gaspar, Diana P; Faria, Vasco; Gonçalves, Lídia M D; Taboada, Pablo; Remuñán-López, Carmen; Almeida, António J

    2016-01-30

    Systemic administration of antitubercular drugs can be complicated by off-target toxicity to cells and tissues that are not infected by Mycobacterium tuberculosis . Delivery of antitubercular drugs via nanoparticles directly to the infected cells has the potential to maximize efficacy and minimize toxicity. The present work demonstrates the potential of solid lipid nanoparticles (SLN) as a delivery platform for rifabutin (RFB). Two different RFB-containing SLN formulations were produced using glyceryl dibehenate or glyceryl tristearate as lipid components. Full characterization was performed in terms of particle size, encapsulation and loading efficiency, morphology by transmission electron microscopy (TEM) and differential scanning calorimetry (DSC) studies. Physical stability was evaluated when formulations were stored at 5 ± 3°C and in the freeze-dried form. Formulations were stable throughout lyophilization without significant variations on physicochemical properties and RFB losses. The SLN showed to be able to endure harsh temperature conditions as demonstrated by dynamic light scattering (DLS). Release studies revealed that RFB was almost completely released from SLN. In vitro studies with THP1 cells differentiated in macrophages showing a nanoparticle uptake of 46 ± 3% and 26 ± 9% for glyceryl dibehenate and glyceryl tristearate SLN, respectively. Cell viability studies using relevant lung cell lines (A549 and Calu-3) revealed low cytotoxicity for the SLN, suggesting these could be new potential vehicles for pulmonary delivery of antitubercular drugs.

  18. Efficacy of nitric oxide, with or without continuing antihypertensive treatment, for management of high blood pressure in acute stroke (ENOS): a partial-factorial randomised controlled trial

    PubMed Central

    2015-01-01

    Summary Background High blood pressure is associated with poor outcome after stroke. Whether blood pressure should be lowered early after stroke, and whether to continue or temporarily withdraw existing antihypertensive drugs, is not known. We assessed outcomes after stroke in patients given drugs to lower their blood pressure. Methods In our multicentre, partial-factorial trial, we randomly assigned patients admitted to hospital with an acute ischaemic or haemorrhagic stroke and raised systolic blood pressure (systolic 140–220 mm Hg) to 7 days of transdermal glyceryl trinitrate (5 mg per day), started within 48 h of stroke onset, or to no glyceryl trinitrate (control group). A subset of patients who were taking antihypertensive drugs before their stroke were also randomly assigned to continue or stop taking these drugs. The primary outcome was function, assessed with the modified Rankin Scale at 90 days by observers masked to treatment assignment. This study is registered, number ISRCTN99414122. Findings Between July 20, 2001, and Oct 14, 2013, we enrolled 4011 patients. Mean blood pressure was 167 (SD 19) mm Hg/90 (13) mm Hg at baseline (median 26 h [16–37] after stroke onset), and was significantly reduced on day 1 in 2000 patients allocated to glyceryl trinitrate compared with 2011 controls (difference −7·0 [95% CI −8·5 to −5·6] mm Hg/–3·5 [–4·4 to −2·6] mm Hg; both p<0·0001), and on day 7 in 1053 patients allocated to continue antihypertensive drugs compared with 1044 patients randomised to stop them (difference −9·5 [95% CI −11·8 to −7·2] mm Hg/–5·0 [–6·4 to −3·7] mm Hg; both p<0·0001). Functional outcome at day 90 did not differ in either treatment comparison—the adjusted common odds ratio (OR) for worse outcome with glyceryl trinitrate versus no glyceryl trinitrate was 1·01 (95% CI 0·91–1·13; p=0·83), and with continue versus stop antihypertensive drugs OR was 1·05 (0·90–1·22; p=0·55). Interpretation

  19. Comparative evaluation of anaerobic biodegradability of hydrocarbons and fatty derivatives currently used as drilling fluids.

    PubMed

    Steber, J; Herold, C P; limia, J M

    1995-08-01

    The examination of a number of potential and currently used carrier fluids for invert emulsion drilling fluids in the ECETOC screening test revealed clear differences with respect to their easy anaerobic biodegradability. Fatty acid- and alcohol-based ester oils exhibited excellent anaerobic degradation to the gaseous final end products of the methanogenic degradation pathway, methane and carbon dioxide. Mineral oils, dialkyl ethers, alpha-olefins, polyalphaolefins, linear alkylbenzenes and an acetal-derivative were not or only slowly degraded. Although the poor degradation results obtained in the stringent ECETOC screening test may not be regarded as final proof of anaerobic recalcitrance, nevertheless, these results were found to be in line with the present understanding of the structural requirements for anaerobic biodegradability of chemicals. The validity of the conclusions drawn is corroborated by published results on the anaerobic biodegradation behaviour of ester oils, mineral oils and alkylbenzenes in marine sediments.

  20. Enhanced surface segregation of poly(methyl methacrylate) end-capped with 2-perfluorooctylethyl methacrylate by introduction of a second block.

    PubMed

    Ni, Huagang; Gao, Jie; Li, Xuehua; Hu, Yanyan; Yan, Donghuan; Ye, XiuYun; Wang, Xinping

    2012-01-01

    New fluorinated copolymers of poly(methyl methacrylate)-b-poly(butyl methacrylate) or poly(n-octadecyl methacrylate) end-capped with 2-perfluorooctylethyl methacrylate (PMMA(x)-b-PBMA(y)-ec-PFMA(z) or PMMA(x)-b-PODMA(y)-ec-PFMA(z)) were synthesized by living atom transfer radical polymerization. Thin films made of PMMA(230)-b-PODMA(y)-ec-PFMA(1) were characterized by differential scanning calorimetry, angle-resolved X-ray photoelectron spectroscopy and X-ray diffraction. These films were found to exhibit robust surface segregation of the end groups. Furthermore, the fluorine enrichment factor at the film surface was found to increase linearly with increasing degree of polymerization of poly(n-octadecyl methacrylate) and its increasing fusion enthalpy in the second block, which enhances the segregation of the fluorinated moieties.

  1. Spectroscopic studies of thiatri-, penta- and heptamethine cyanine dyes II. Infrared and resonance Raman spectra of thiatri-, penta- and heptamethine cyanine dyes

    NASA Astrophysics Data System (ADS)

    Fujimoto, Yasuhiko; Katayama, Norihisa; Ozaki, Yukihiro; Yasui, Shigeo; Iriyama, Keiji

    1992-11-01

    Infrared (IR) and resonance Raman (RR) spectra of thiatri-, penta- and heptamethine cyanine dyes in the solid state and in solution have been measured. Most of the intense bands observed in the 1600-1100 cm -1 region of the RR spectra may be assigned to totally symmetric stretching modes of the central conjugated system of the cyanines, while most of the strong IR bands in the 1600-1300 cm -1 region are probably due to antisymmetric stretching modes. The intense RR bands do not have their counterparts in the IR spectra and vice versa. A pseudo-mutual exclusion rule seems to be operative for the cyanine vibrational spectra in the 1600-1300 cm -1 region, indicating that the central conjugated systems of the cyanines have nearly symmetrical structure, i.e. the extended all-trans forms of the methine chains and the bond orders of 1.5 of the CC and CN bonds in both the solution and solid states. The IR spectra of 3-ethyl-2-[3-(3-ethyl-2-benzothiazolinylidene)-1-propenyl]benzothiazolium iodide (NK-76) and 3-ethyl-2-[7-(3-ethyl-2-benzothiazolinylidene)-1,3,5-heptatrienyl]benzothiazolium iodide (NK-126) change little between the solid and solution states while those of 3-octadecyl-2-[3-(3-octadecyl-2-benzothiazolinylidene)-1-propenyl]benzothiazolium iodide (NK-2560) and 3-octadecyl-2-[7-(3-octadecyl-2-benzothiazolinylidene)-1,3,5-heptatrienyl]benzothiazolium perchlorate (NK-2861) alter significantly between the two states in the frequencies of bands due to the stretching modes of their central conjugated systems. The results suggest that the electronic states of the central conjugated systems of NK-2560 and NK-2861 undergo appreciable changes on going from the solid to the solution states.

  2. Transesterification of triglycerides using nitrogen-functionalized carbon nanotubes.

    PubMed

    Villa, Alberto; Tessonnier, Jean-Philippe; Majoulet, Olivier; Su, Dang Sheng; Schlögl, Robert

    2010-02-22

    Nitrogen-functionalized carbon nanotubes were synthesized by grafting amino groups to the surface of the nanotubes. The nanotubes exhibited promising results in the base-catalyzed liquid phase transesterification of glyceryl tributyrate with methanol, which is a model reaction for the production of biodiesel. The concentration of the active sites and the reaction parameters, such as temperature and glyceryl tributyrate to methanol ratio, were shown to significantly affect catalytic performance. The grafting technique employed allowed for design and control of the active sites. As a consequence, it was possible to design a nitrogen-functionalized carbon nanotube catalyst with a few strong, basic groups. This might be of interest for carbohydrate conversion reactions where strong basic sites are required but the pH of the solution should remain mild to avoid the degradation of the reactants and/or products.

  3. The control of ice crystal growth and effect on porous structure of konjac glucomannan-based aerogels.

    PubMed

    Ni, Xuewen; Ke, Fan; Xiao, Man; Wu, Kao; Kuang, Ying; Corke, Harold; Jiang, Fatang

    2016-11-01

    Konjac glucomannan (KGM)-based aerogels were prepared using a combination of sol-gel and freeze-drying methods. Preparation conditions were chosen to control ice crystal growth and aerogel structure formation. The ice crystals formed during pre-freezing were observed by low temperature polarizing microscopy, and images of aerogel pores were obtained by scanning electron microscopy. The size of ice crystals were calculated and size distribution maps were drawn, and similarly for aerogel pores. Results showed that ice crystal growth and aerogel pore sizes may be controlled by varying pre-freezing temperatures, KGM concentration and glyceryl monostearate concentration. The impact of pre-freezing temperatures on ice crystal growth was explained as combining ice crystal growth rate with nucleation rate, while the impacts of KGM and glyceryl monostearate concentration on ice crystal growth were interpreted based on their influences on sol network structure.

  4. Electrochemical characterization of bilayer lipid membrane-semiconductor junctions

    SciTech Connect

    Zhao, Xiao Kang; Baral, S.; Fendler, J.H. )

    1990-03-08

    Three different systems of glyceryl monooleate (GMO), bilayer lipid membrane (BLM) supported semiconductor particles have been prepared and characterized. A single composition of particulate semiconductor deposited only on one side of the BLM constituted system A, two different compositions of particulate semiconductors sequentially deposited on the same side of the BLM represented system B, and two different compositions of particulate semiconductors deposited on the opposite sides of the BLM made up system C.

  5. Automated Nitrocellulose Analysis

    DTIC Science & Technology

    1978-12-01

    is acceptable. (4) As would be expected from the theory of osmosis , a high saline content in the dialysis recipient stream (countersolution) is of...Block 39, II different from Report; IS. SUPPLEMENTARY NOTES IS. KEY WOROS (Continue on rereri Analysis Automated analysis Dialysis Glyceryl...Technicon AutoAnalyzer, involves aspiration of a stirred nitrocellulose suspension, dialysis against 9 percent saline, and hydrolysis with 5N sodium

  6. 21 CFR 184.1901 - Triacetin.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Triacetin. 184.1901 Section 184.1901 Food and....1901 Triacetin. (a) Triacetin (C8 H14O6, CAS Reg. No. 102-76-1), also known as 1,2,3,-propanetriol triacetate or glyceryl triacetate, is the triester of glycerin and acetic acid. Triacetin can be prepared...

  7. Utilization of ascites plasma very low density lipoprotein triglycerides by Ehrlich cells.

    PubMed

    Brenneman, D E; Spector, A A

    1974-07-01

    Much of the lipid present in the ascites plasma in which Ehrlich cells grow is contained in very low density lipoproteins (VLDL). Chemical measurements indicated that triglycerides were taken up by the cells during in vitro incubation with ascites VLDL. When tracer amounts of radioactive triolein were incorporated into the ascites VLDL, the percentage uptakes of glyceryl tri[1-(14)C]oleate and triglycerides measured chemically were similar. The cells also took up [2-(3)H]glyceryl trioleate that was added to VLDL, but the percentage of available (3)H recovered in the cell lipids was 30-40% less than that of (1 4)C from glyceryl tri[1-(1 4)C]oleate. This difference was accounted for by water-soluble (3)H that accumulated in the incubation medium, suggesting that extensive hydrolysis accompanied the uptake of VLDL triglycerides. Radioactive fatty acids derived from the VLDL triglycerides were incorporated into cell phospholipids, glycerides, and free fatty acids, and they also were oxidized to CO(2). Triglyceride utilization increased as the VLDL concentration was raised. These results suggest that one function of the ascites plasma VLDL may be to supply fatty acid to the Ehrlich cells and that the availability of fatty acid to this tumor is determined in part by the ascites plasma VLDL concentration. Although Ehrlich cells incorporate almost no free glycerol into triglycerides, considerable amounts of [2-(3)H]glyceryl trioleate radioactivity were recovered in cell triglycerides. This indicates that at least some VLDL triglycerides were taken up intact. The net uptake of VLDL protein and cholesterol was very small relative to the triglyceride uptake, suggesting that intact triglycerides are transferred from the ascites VLDL to the Ehrlich cells and that hydrolysis occurs after the triglyceride is associated with the cells.

  8. Direct Synthesis of ESBO Derivatives-18O Labelled with Dioxirane

    PubMed Central

    Tommasi, Immacolata; Fusco, Caterina

    2013-01-01

    This work addresses a new approach developed in our laboratory, consisting in the application of isolated dimethyldioxirane (DDO, 1a) labelled with 18O for synthesis of epoxidized glyceryl linoleate (Gly-LLL, 2). We expect that this work could contribute in improving analytical methods for the determination of epoxidized soybean oil (ESBO) in complex food matrices by adopting an 18O-labelled-epoxidized triacylglycerol as an internal standard. PMID:24163617

  9. In vitro suppression of drug-induced methaemoglobin formation by Intralipid(®) in whole human blood: observations relevant to the 'lipid sink theory'.

    PubMed

    Samuels, T L; Willers, J W; Uncles, D R; Monteiro, R; Halloran, C; Dai, H

    2012-01-01

    To provide further evidence for the lipid sink theory, we have developed an in vitro model to assess the effect of Intralipid® 20% on methaemoglobin formation by drugs of varying lipid solubility. Progressively increasing Intralipid concentrations from 4 to 24 mg.ml⁻¹ suppressed methaemoglobin formation by the lipid soluble drug glyceryl trinitrate in a dose-dependent manner (p < 0.001). Both dose and timing of administration of Intralipid to blood previously incubated with glyceryl trinitrate for 10 and 40 min resulted in significant suppression of methaemoglobin formation (p < 0.0001 and p < 0.05, respectively). Mathematical modelling demonstrated that the entire process of methaemoglobin formation by glyceryl trinitrate was slowed down in the presence of Intralipid. Intralipid did not significantly suppress methaemoglobin formation induced by 2-amino-5-hydroxytoluene (partially lipid soluble) or sodium nitrite (lipid insoluble; both p > 0.5). This work may assist determination of the suitability of drugs taken in overdose for which Intralipid might be deployed.

  10. Acute Lipotoxicity Regulates Severity of Biliary Acute Pancreatitis without Affecting Its Initiation

    PubMed Central

    Durgampudi, Chandra; Noel, Pawan; Patel, Krutika; Cline, Rachel; Trivedi, Ram N.; DeLany, James P.; Yadav, Dhiraj; Papachristou, Georgios I.; Lee, Kenneth; Acharya, Chathur; Jaligama, Deepthi; Navina, Sarah; Murad, Faris; Singh, Vijay P.

    2015-01-01

    Obese patients have worse outcomes during acute pancreatitis (AP). Previous animal models of AP have found worse outcomes in obese rodents who may have a baseline proinflammatory state. Our aim was to study the role of acute lipolytic generation of fatty acids on local severity and systemic complications of AP. Human postpancreatitis necrotic collections were analyzed for unsaturated fatty acids (UFAs) and saturated fatty acids. A model of biliary AP was designed to replicate the human variables by intraductal injection of the triglyceride glyceryl trilinoleate alone or with the chemically distinct lipase inhibitors orlistat or cetilistat. Parameters of AP etiology and outcomes of local and systemic severity were measured. Patients with postpancreatitis necrotic collections were obese, and 13 of 15 had biliary AP. Postpancreatitis necrotic collections were enriched in UFAs. Intraductal glyceryl trilinoleate with or without the lipase inhibitors resulted in oil red O–positive areas, resembling intrapancreatic fat. Both lipase inhibitors reduced the glyceryl trilinoleate–induced increase in serum lipase, UFAs, pancreatic necrosis, serum inflammatory markers, systemic injury, and mortality but not serum alanine aminotransferase, bilirubin, or amylase. We conclude that UFAs are enriched in human necrotic collections and acute UFA generation via lipolysis worsens pancreatic necrosis, systemic inflammation, and injury associated with severe AP. Inhibition of lipolysis reduces UFA generation and improves these outcomes of AP without interfering with its induction. PMID:24854864

  11. Inhibition of Listeria monocytogenes by fatty acids and monoglycerides.

    PubMed

    Wang, L L; Johnson, E A

    1992-02-01

    Fatty acids and monoglycerides were evaluated in brain heart infusion broth and in milk for antimicrobial activity against the Scott A strain of Listeria monocytogenes. C12:0, C18:3, and glyceryl monolaurate (monolaurin) had the strongest activity in brain heart infusion broth and were bactericidal at 10 to 20 micrograms/ml, whereas potassium (K)-conjugated linoleic acids and C18:2 were bactericidal at 50 to 200 micrograms/ml. C14:0, C16:0, C18:0, C18:1, glyceryl monomyristate, and glyceryl monopalmitate were not inhibitory at 200 micrograms/ml. The bactericidal activity in brain heart infusion broth was higher at pH 5 than at pH 6. In whole milk and skim milk, K-conjugated linoleic acid was bacteriostatic and prolonged the lag phase especially at 4 degrees C. Monolaurin inactivated L. monocytogenes in skim milk at 4 degrees C, but was less inhibitory at 23 degrees C. Monolaurin did not inhibit L. monocytogenes in whole milk because of the higher fat content. Other fatty acids tested were not effective in whole or skim milk. Our results suggest that K-conjugated linoleic acids or monolaurin could be used as an inhibitory agent against L. monocytogenes in dairy foods.

  12. Characterization of semi-solid Self-Emulsifying Drug Delivery Systems (SEDDS) of atorvastatin calcium by Raman image spectroscopy and chemometrics.

    PubMed

    Breitkreitz, Márcia C; Sabin, Guilherme P; Polla, Griselda; Poppi, Ronei J

    2013-01-25

    A methodology based on Raman image spectroscopy and chemometrics for homogeneity evaluation of formulations containing atorvastatin calcium in Gelucire(®) 44/14 is presented. In the first part of the work, formulations with high amounts of Gelucire(®) 44/14 (80%) and solvents of different polarities (diethylene glycol monoethyl ether, propyleneglycol, propylene glycol monocaprylate and glyceryl mono/dicaprylate/caprate) were prepared for miscibility screening evaluation by classical least squares (CLS). It was observed that Gelucire(®) 44/14 presented higher affinity for the lipophilic solvents glyceryl mono/dicaprylate/caprate and propylene glycol monocaprylate, whose samples were observed to be homogeneous, and lower affinity for the hydrophilic solvents diethylene glycol monoethyl ether and propyleneglycol, whose samples were heterogeneous. In the second part of the work, the ratio of glyceryl mono/dicaprylate/caprate and Gelucire(®) 44/14 was determined based on studies in water and allowed the selection of the proportions of these two excipients in the preconcentrate that provided supersaturation of atorvastatin upon dilution. The preconcentrate was then evaluated for homogeneity by partial least squares (PLS) and an excellent miscibility was observed in this proportion as well. Therefore, it was possible to select a formulation that presented simultaneously homogeneous preconcentrate and solubility enhancement in water by Raman image spectroscopy and chemometrics.

  13. Development of novel sustained release matrix pellets of betahistine dihydrochloride: effect of lipophilic surfactants and co-surfactants.

    PubMed

    Shamma, Rehab Nabil; Basalious, Emad B; Shoukri, Raguia

    2012-01-01

    Sustained release matrix pellets of the freely water soluble drug, betahistine dihydrochloride (BH), were prepared using freeze pelletization technique. Different waxes and lipids (cetyl alcohol, beeswax, glyceryl tripalmitate (GTP) and glyceryl tristearate) were evaluated for the preparation of matrix pellets. A D-optimal design was employed for the optimization and to explore the effect of drug loading (X(1)), concentration of lipophilic surfactant (X(2)), concentration of co-surfactant (X(3)) and wax type (X(4)) on the release extent of the drug from matrix pellets. The entrapment efficiency (Y(1)), pellet diameter (Y(2)), and the percentage drug released at given times were selected as dependent variables. Results revealed a significant impact of all independent variables on drug release from the formulated pellets. The lipophilic surfactant significantly increased both the entrapment efficiency and the in vitro drug release and significantly decreased the pellet size. The optimized BH-loaded pellets were composed of 19.95% drug loading, 9.95% Span(®) 80 (surfactant), 0.25% Capmul(®) (co-surfactant) using glyceryl tripalmitate as a matrix former. The release profiles of the drug from hard gelatin capsule containing optimized pellets equivalent to 32 mg BH was similar to that of target release model for once-daily administration based on similarity factor. It could be concluded that a promising once-daily capsule containing sustained release pellets of BH was successfully designed.

  14. Immobilization of Lipase from Penicillium sp. Section Gracilenta (CBMAI 1583) on Different Hydrophobic Supports: Modulation of Functional Properties.

    PubMed

    Turati, Daniela F M; Morais Júnior, Wilson G; Terrasan, César R F; Moreno-Perez, Sonia; Pessela, Benevides C; Fernandez-Lorente, Gloria; Guisan, Jose M; Carmona, Eleonora C

    2017-02-22

    Lipases are promising enzymes that catalyze the hydrolysis of triacylglycerol ester bonds at the oil/water interface. Apart from allowing biocatalyst reuse, immobilization can also affect enzyme structure consequently influencing its activity, selectivity, and stability. The lipase from Penicillium sp. section Gracilenta (CBMAI 1583) was successfully immobilized on supports bearing butyl, phenyl, octyl, octadecyl, and divinylbenzyl hydrophobic moieties wherein lipases were adsorbed through the highly hydrophobic opened active site. The highest activity in aqueous medium was observed for the enzyme adsorbed on octyl support, with a 150% hyperactivation regarding the soluble enzyme activity, and the highest adsorption strength was verified with the most hydrophobic support (octadecyl Sepabeads), requiring 5% Triton X-100 to desorb the enzyme from the support. Most of the derivatives presented improved properties such as higher stability to pH, temperature, and organic solvents than the covalently immobilized CNBr derivative (prepared under very mild experimental conditions and thus a reference mimicking free-enzyme behavior). A 30.8- and 46.3-fold thermostabilization was achieved in aqueous medium, respectively, by the octyl Sepharose and Toyopearl butyl derivatives at 60 °C, in relation to the CNBr derivative. The octyl- and phenyl-agarose derivatives retained 50% activity after four and seven cycles of p-nitrophenyl palmitate hydrolysis, respectively. Different derivatives exhibited different properties regarding their properties for fish oil hydrolysis in aqueous medium and ethanolysis in anhydrous medium. The most active derivative in ethanolysis of fish oil was the enzyme adsorbed on a surface covered by divinylbenzyl moieties and it was 50-fold more active than the enzyme adsorbed on octadecyl support. Despite having identical mechanisms of immobilization, different hydrophobic supports seem to promote different shapes of the adsorbed open active site of the

  15. Thermoreversible Gels Composed of Colloidal Silica Rods with Short-Range Attractions

    DOE PAGES

    Murphy, Ryan P.; Hong, Kunlun; Wagner, Norman J.

    2016-07-28

    Dynamic arrest transitions of colloidal suspensions containing non-spherical particles are of interest for the design and processing of various particle technologies. To better understand the effects of particle shape anisotropy and attraction strength on gel and glass formation, we present a colloidal model system of octadecyl-coated silica rods, termed as adhesive hard rods (AHR), which enables control of rod aspect ratio and temperature-dependent interactions. The aspect ratios of silica rods were controlled by varying the initial TEOS concentration following the work of Kuijk et al. (J. Am. Chem. Soc., 2011, 133, 2346–2349) and temperature-dependent attractions were introduced by coating themore » calcined silica rods with an octadecyl-brush and suspending in tetradecane. The rod length and aspect ratio were found to increase with TEOS concentration as expected, while other properties such as the rod diameter, coating coverage, density, and surface roughness were nearly independent of the aspect ratio. Ultra-small angle X-ray scattering measurements revealed temperature-dependent attractions between octadecyl-coated silica rods in tetradecane, as characterized by a low-q upturn in the scattered intensity upon thermal quenching. Lastly, the rheology of a concentrated AHR suspension in tetradecane demonstrated thermoreversible gelation behavior, displaying a nearly 5 orders of magnitude change in the dynamic moduli as the temperature was cycled between 15 and 40 °C. We find the adhesive hard rod model system serves as a tunable platform to explore the combined influence of particle shape anisotropy and attraction strength on the dynamic arrest transitions in colloidal suspensions with thermoreversible, short-range attractions.« less

  16. Effect of alkyl chain length on the rotational diffusion of nonpolar and ionic solutes in 1-alkyl-3-methylimidazolium-bis(trifluoromethylsulfonyl)imides.

    PubMed

    Gangamallaiah, V; Dutt, G B

    2013-10-10

    Rotational diffusion of a nonpolar solute 9-phenylanthracene (9-PA) and a cationic solute rhodamine 110 (R110) has been examined in a series of 1-alkyl-3-methylimidazolium (alkyl = octyl, decyl, dodecyl, tetradecyl, hexadecyl, and octadecyl) bis(trifluoromethylsulfonyl)imides to understand the influence of alkyl chain length on solute rotation. In this study, reorientation times (τr) have been measured as a function of viscosity (η) by varying the temperature (T) of the solvents. These results have been analyzed using the Stokes-Einstein-Debye (SED) hydrodynamic theory along with the ones obtained for the same solutes in 1-alkyl-3-methylimidazolium (alkyl = methyl, ethyl, propyl, butyl, and hexyl) bis(trifluoromethylsulfonyl)imides (Gangamallaiah and Dutt, J. Phys. Chem. B 2012, 116, 12819-12825). It has been noticed that the data for 9-PA and R110 follows the relation τr = A(η/T)(n) with A being the ratio of hydrodynamic volume of the solute to the Boltzmann constant and n = 1 as envisaged by the SED theory. However, upon increasing the alkyl chain length from methyl to octadecyl significant deviations from the SED theory have been observed especially from the octyl derivative onward. From methyl to octadecyl derivatives, the value of A decreases by a factor of 3 for both the solutes and n by a factor of 1.4 and 1.6 for 9-PA and R110, respectively. These observations have been rationalized by taking into consideration the organized structure of the ionic liquids, whose influence appears to be pronounced when the number of carbon atoms in the alkyl chain attached to the imidazolium cation exceeds eight.

  17. Thermoreversible Gels Composed of Colloidal Silica Rods with Short-Range Attractions

    SciTech Connect

    Murphy, Ryan P.; Hong, Kunlun; Wagner, Norman J.

    2016-07-28

    Dynamic arrest transitions of colloidal suspensions containing non-spherical particles are of interest for the design and processing of various particle technologies. To better understand the effects of particle shape anisotropy and attraction strength on gel and glass formation, we present a colloidal model system of octadecyl-coated silica rods, termed as adhesive hard rods (AHR), which enables control of rod aspect ratio and temperature-dependent interactions. The aspect ratios of silica rods were controlled by varying the initial TEOS concentration following the work of Kuijk et al. (J. Am. Chem. Soc., 2011, 133, 2346–2349) and temperature-dependent attractions were introduced by coating the calcined silica rods with an octadecyl-brush and suspending in tetradecane. The rod length and aspect ratio were found to increase with TEOS concentration as expected, while other properties such as the rod diameter, coating coverage, density, and surface roughness were nearly independent of the aspect ratio. Ultra-small angle X-ray scattering measurements revealed temperature-dependent attractions between octadecyl-coated silica rods in tetradecane, as characterized by a low-q upturn in the scattered intensity upon thermal quenching. Lastly, the rheology of a concentrated AHR suspension in tetradecane demonstrated thermoreversible gelation behavior, displaying a nearly 5 orders of magnitude change in the dynamic moduli as the temperature was cycled between 15 and 40 °C. We find the adhesive hard rod model system serves as a tunable platform to explore the combined influence of particle shape anisotropy and attraction strength on the dynamic arrest transitions in colloidal suspensions with thermoreversible, short-range attractions.

  18. In vitro intestinal bioaccessibility of alkylglycerols versus triacylglycerols as vehicles of butyric acid.

    PubMed

    Martín, Diana; Morán-Valero, María I; Señoráns, Francisco J; Reglero, Guillermo; Torres, Carlos F

    2011-03-01

    Butyric acid has been the subject of much attention last years due to its bioactivity. However, the potential advantages of butyrate are limited by the problem to reach enough plasma concentrations; therefore, pro-drugs have been proposed as an alternative to natural butyrate. A comparative study on in vitro intestinal digestion of 2,3-dibutyroil-1-O-octadecyl glycerol (D-SCAKG) and tributyrin (TB), as potential pro-drugs of butyric acid, was performed. Aliquots were taken at different times of digestion for studying the extent and rate of hydrolysis of both substrates. The micellar phase (MP) and oily phase (OP) formed in the digestion media were separated and their composition in lipid products was analyzed. Initially, it was confirmed that the in vitro model reproduced physiological results by testing against olive oil as a standard lipid. The progress of in vitro intestinal digestion of D-SCAKG was slower than that of TB. TB hydrolyzed completely to butyric acid, whereas D-SCAKG mainly yielded 2-butyroil-1-O-octadecyl glycerol (M-SCAKG), followed by butyric acid and 1-O-octadecyl glycerol (AKG). The MP from both substrates mainly consisted of butyric acid. Minor levels of M-SCAKG and AKG were also found in the MP after hydrolysis of D-SCAKG, the M-SCAKG being mainly distributed in the OP. Therefore, D-SCAKG produced a stable form of esterified butyric acid as M-SCAKG after in vitro intestinal digestion, unlike TB. Additionally, such a product would integrate both bioactive compounds, butyric acid and alkylglycerol, within the same molecule. Free butyric acid and AKG would be also released, which are lipid products of interest as well.

  19. Comparison of solvent extraction and solid-phase extraction for the determination of polychlorinated biphenyls in transformer oil.

    PubMed

    Mahindrakar, A N; Chandra, S; Shinde, L P

    2014-01-01

    Solid-phase extraction (SPE) of nine polychlorinated biphenyls (PCBs) from transformer oil samples was evaluated using octadecyl (CI8)-bonded porous silica. The efficiency of SPE of these PCBs was compared with those obtained by solvent extraction with DMSO and hexane. Average recoveries exceeding 95% for these PCBs were obtained via the SPE method using small cartridges containing 100mg of 40 pm CI8-bonded porous silica. The average recovery by solvent extraction with DMSO and hexane exceeded 83%. It was concluded that the recoveries and precision for the solvent extraction of PCBs were poorer than those for the SPE.

  20. Sorption of certain isatins on various sorbents under RP-HPLC conditions

    NASA Astrophysics Data System (ADS)

    Konstantinov, A. V.; Shafigulin, R. V.; Il'in, M. M.; Davankov, V. A.; Bulanova, A. V.; Purygin, P. P.

    2013-06-01

    The results from chromatographic analysis of biologically active isatin derivatives on hyper-crosslinked polystyrene (HCLPS) and silica gel modified by octadecyl groups (SilC18) are presented. The constants of distribution of sorbates between a mobile phase and the investigated sorbents ( K x ) and the changes in the standard differential molar Gibbs energies of adsorption (Δ _a bar G^circ ) are calculated, along with the chromatographic retention-physicochemical property of sorbate dependences. It is found that the equations describing these dependences have high forecasting ability with respect to the values of retention factors of the investigated sorbates.

  1. Theory analysis of mass spectra of long-chain isocyanates.

    PubMed

    Liu, Dongliang; Hao, Ce; Zhang, Hua; Qiao, Weihong; Li, Zongshi; Yu, Guanghui; Yan, Kelu; Guo, Yuliang; Cheng, Lvbo

    2008-07-01

    Electron impact mass spectra of four long-chain isocyanates, lauryl isocyanate, tetradecyl isocyanate, hexadecyl isocyanate and octadecyl isocyanate, were obtained with a GCT high-resolution time-of-flight mass spectrometer. The four isocyanates studied gave a common base peak of m/z 99, which suggested the formation of a stable six-membered ring structure to decentralize the positive charge. Quantum-mechanical energy calculation justified that the six-membered ring base peak had the lowest energy. The positive charge assigned during the fragmentation of the radical cation, and the relative intensity of the fragment ion peaks, were explained by quantum-mechanical calculations as well.

  2. Determination of nadolol in serum by high-performance liquid chromatography with fluorimetric detection.

    PubMed

    Noguchi, H; Yoshida, K; Murano, M; Naruto, S

    1992-01-17

    A sensitive high-performance liquid chromatographic method for a routine assay of nadolol in serum is described. Serum samples spiked with atenolol (internal standard) were extracted with diethyl ether. After centrifugation, the organic layer was evaporated to dryness. The residue was redissolved in the mobile phase and injected onto an octadecyl silica column (150 mm x 4.6 mm I.D.). The mobile phase was 0.05 M ammonium acetate (pH 4.5)-acetonitrile (85:15, v/v). Fluorometric detection (excitation 230 nm, emission 300 nm) was used. The minimum detectable level of nadolol in serum was 1 ng/ml.

  3. Functional double-shelled silicon nanocrystals for two-photon fluorescence cell imaging: spectral evolution and tuning

    NASA Astrophysics Data System (ADS)

    Chandra, Sourov; Ghosh, Batu; Beaune, Grégory; Nagarajan, Usharani; Yasui, Takao; Nakamura, Jin; Tsuruoka, Tohru; Baba, Yoshinobu; Shirahata, Naoto; Winnik, Françoise M.

    2016-04-01

    Functional near-IR (NIR) emitting nanoparticles (NPs) adapted for two-photon excitation fluorescence cell imaging were obtained starting from octadecyl-terminated silicon nanocrystals (ncSi-OD) of narrow photoluminescence (PL) spectra having no long emission tails, continuously tunable over the 700-1000 nm window, PL quantum yields exceeding 30%, and PL lifetimes of 300 μs or longer. These NPs, consisting of a Pluronic F127 shell and a core made up of assembled ncSi-OD kept apart by an octadecyl (OD) layer, were readily internalized into the cytosol, but not the nucleus, of NIH3T3 cells and were non-toxic. Asymmetrical field-flow fractionation (AF4) analysis was carried out to determine the size of the NPs in water. HiLyte Fluor 750 amine was linked via an amide link to NPs prepared with Pluronic-F127-COOH, as a first demonstration of functional NIR-emitting water dispersible ncSi-based nanoparticles.Functional near-IR (NIR) emitting nanoparticles (NPs) adapted for two-photon excitation fluorescence cell imaging were obtained starting from octadecyl-terminated silicon nanocrystals (ncSi-OD) of narrow photoluminescence (PL) spectra having no long emission tails, continuously tunable over the 700-1000 nm window, PL quantum yields exceeding 30%, and PL lifetimes of 300 μs or longer. These NPs, consisting of a Pluronic F127 shell and a core made up of assembled ncSi-OD kept apart by an octadecyl (OD) layer, were readily internalized into the cytosol, but not the nucleus, of NIH3T3 cells and were non-toxic. Asymmetrical field-flow fractionation (AF4) analysis was carried out to determine the size of the NPs in water. HiLyte Fluor 750 amine was linked via an amide link to NPs prepared with Pluronic-F127-COOH, as a first demonstration of functional NIR-emitting water dispersible ncSi-based nanoparticles. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr01437b

  4. Predicting the Conditions for Homeotropic Anchoring of Liquid Crystals at a Soft Surface. 4-n-Pentyl-4'-cyanobiphenyl on Alkylsilane Self-Assembled Monolayers.

    PubMed

    Roscioni, Otello Maria; Muccioli, Luca; Zannoni, Claudio

    2017-04-05

    We have studied, using atomistic molecular dynamics simulations, the alignment of the nematic liquid-crystal 4-n-pentyl-4'-cyanobiphenyl (5CB) on self-assembled monolayers (SAMs) formed from octadecyl- and/or hexyltrichlorosilane (OTS and HTS) attached to glassy silica. We find a planar alignment on OTS at full coverage and an intermediate situation at partial OTS coverage because of the penetration of 5CB molecules into the monolayer, which also removes the tilt of the OTS SAM. Binary mixtures of HTS and OTS SAMs instead induce homeotropic (i.e., perpendicular) alignment. A comparison with the existing experimental literature is provided.

  5. Comparison of solid-phase extraction sorbents for sample clean-up in the analysis of organic explosives.

    PubMed

    Tachon, Romain; Pichon, Valérie; Barbe Le Borgne, Martine; Minet, Jean-Jacques

    2008-03-21

    A solid-phase extraction procedure was developed for the clean-up of forensic samples collected at bombing scenes. Recoveries of common organic explosives from methanolic extracts diluted with water were studied on different hydrophobic sorbents. Polymeric sorbents retained explosive compounds better than octadecyl-bonded silica-based materials. Clean-up efficiency was evaluated with simulated samples prepared from commercial motor oil. Polymeric sorbent with the smallest specific surface area was found to limit the coextraction of matrix components. Performance of the method was confirmed by a reduction of ion suppression in LC/MS analysis.

  6. High-resolution crystal spectrometer for the 10-60 (angstrom) EUV region

    SciTech Connect

    Beiersdorfer, P; Brown, G V; Goddard, R; Wargelin, B J

    2004-02-20

    A vacuum crystal spectrometer with nominal resolving power approaching 1000 is described for measuring emission lines with wavelength in the extreme ultraviolet region up to 60 Angstroms. The instrument utilizes a flat octadecyl hydrogen maleate (OHM) crystal and a thin-window 1-D position-sensitive gas proportional detector. This detector employs a 1 {micro}m-thick 100 x8 mm{sup 2} aluminized polyimide window and operates at one atmosphere pressure. The spectrometer has been implemented on the Livermore electron beam ion traps. The performance of the instrument is illustrated in measurements of the newly discovered magnetic field-sensitive line in Ar{sup 8+}.

  7. [Simultaneous separation of organic acid and organic salts by electrostatic ion chromatography].

    PubMed

    Shen, G J; Yang, R F; Yu, A M

    2001-09-01

    The electrostatic ion chromatographic column was prepared by coating conjugated acid salt micelles on the surface of octadecyl silica stationary phase. Pure water was used as mobile phase, and the conductance detector was connected on-line to electrostatic ion chromatograph. The conditions under which organic acid and organic salts were detected were studied. The mechanism for the above separation is discussed. Sodium benzoate and citric acid in Lichee drink were separated and determined. This method is rapid, simple with little interference and good reproducibility without any pollution since the mobile phase is water. This is an environmental friendly analytical method.

  8. Alkyl ferulates in wound healing potato tubers.

    PubMed

    Bernards, M A; Lewis, N G

    1992-10-01

    Seven ferulic acid esters of 1-alkanols ranging in carbon length from C16 to C28 were synthesized and an HPLC protocol for their separation developed. Extracts prepared from wound healing potato (Solanum tuberosum) tubers and analysed by HPLC indicated that alkyl ferulate esters begin to accumulate 3-7 days after wound treatment. Of the nine esters identified by EIMS, (including two esters of odd chain length alkanols) hexadecyl and octadecyl ferulates were predominant. Alkyl ferulate esters were restricted to the wound periderm.

  9. Retention of Proteins and Metalloproteins in Open Tubular Capillary Electrochromatography with Etched Chemically Modified Columns

    PubMed Central

    Pesek, Joseph J.; Matyska, Maria T.; Salgotra, Vasudha

    2010-01-01

    Etched chemically modified capillaries with two different bonded groups (pentyl and octadecyl) are compared for their migration behavior of several common proteins and metalloproteins as well as metalloproteinases. Migration times, efficiency and peak shape are evaluated over the pH range of 2.1 to 8.1 to determine any effects of the bonded group on the electrochromatographic behavior of these compounds. One goal was to determine if the relative hydrophobicity of the stationary phase has a significant effect on proteins in the open tubular format of capillary electrochromatography as it does in HPLC. Reproducibility of the migration times is also investigated. PMID:18850653

  10. Surfactants and Desensitizing Wax Substitutes for TNT-Based Systems.

    DTIC Science & Technology

    1994-10-01

    Phthalimides with long-chain alkyl groups have been found to be very wax-like. They are made from phthalic anhydride and an alkyl amine. Pure N-octadecyl...Phthalate Half-Esters Phthalic anhydride (5.07 g) and 14.9 grams of Unilin 350 alcohol were charged to a container and heated with stirring for 2 hours at...With The Enthalpy Of ....... 40 Wax Desensitizers 7. DSC Of Ganex WP-660/TNT Mixture ........................ 50 8. DSC Of Solsperse 5000/TNT Mixture

  11. Alkylated phenol series in lacustrine black shales from the Nördlinger Ries, southern Germany.

    PubMed

    Barakat, Assem O; Baumgart, Susan; Brocks, Peter; Scholz-Böttcher, Barbara M; Rullkötter, Jürgen

    2012-08-01

    Several series of alkylated phenols were detected for the first time in the extractable bitumens of organic matter-rich sediments from the Nördlinger Ries (southern Germany). Most abundant and significant constituents comprise those with n-octadecyl, n-eicosanyl, phytanyl, and iso-pentadecyl and anteiso-pentadecyl substituents. The structures of these compounds are suggested from mass spectrometric and retention time data and coinjection with synthetic standards. Diagenetic alteration of phenolic algal lipids is suggested as a possible way to the formation of these compounds in the Nördlinger Ries sediments.

  12. Copper(II) complexes of lipophilic aminoglycoside derivatives for the amino acid enantiomeric separation by ligand-exchange liquid chromatography.

    PubMed

    Zaher, Mustapha; Baussanne, Isabelle; Ravelet, Corinne; Halder, Somnath; Haroun, Mohamed; Fize, Jennifer; Décout, Jean-Luc; Peyrin, Eric

    2008-03-28

    In this paper, a new class of ligand-exchange chiral stationary phase (LE-CSP) based on the copper complexes of lipophilic aminoglycoside derivatives was reported. Different stationary phases were developed by coating reversed-phase liquid chromatography supports with three neamine derivatives carrying a lipophilic octadecyl chain at the 4', 5 and 6 positions, respectively. The enantioselective ability of these LE neamine-based CSPs was evaluated and the 4'-derivative coated column was found to be the most interesting one for the amino acid resolution. The effects of the variation of several chromatographic parameters on the enantioseparation were evaluated in order to identify the analysis optimal conditions.

  13. Short-chain flavor ester synthesis in organic media by an E. coli whole-cell biocatalyst expressing a newly characterized heterologous lipase.

    PubMed

    Brault, Guillaume; Shareck, François; Hurtubise, Yves; Lépine, François; Doucet, Nicolas

    2014-01-01

    Short-chain aliphatic esters are small volatile molecules that produce fruity and pleasant aromas and flavors. Most of these esters are artificially produced or extracted from natural sources at high cost. It is, however, possible to 'naturally' produce these molecules using biocatalysts such as lipases and esterases. A gene coding for a newly uncovered lipase was isolated from a previous metagenomic study and cloned into E. coli BL21 (DE3) for overexpression using the pET16b plasmid. Using this recombinant strain as a whole-cell biocatalyst, short chain esters were efficiently synthesized by transesterification and esterification reactions in organic media. The recombinant lipase (LipIAF5-2) showed good affinity toward glyceryl trioctanoate and the highest conversion yields were obtained for the transesterification of glyceryl triacetate with methanol. Using a simple cetyl-trimethylammonium bromide pretreatment increased the synthetic activity by a six-fold factor and the whole-cell biocatalyst showed the highest activity at 40°C with a relatively high water content of 10% (w/w). The whole-cell biocatalyst showed excellent tolerance to alcohol and short-chain fatty acid denaturation. Substrate affinity was equally effective with all primary alcohols tested as acyl acceptors, with a slight preference for methanol. The best transesterification conversion of 50 mmol glyceryl triacetate into isoamyl acetate (banana fragrance) provided near 100% yield after 24 hours using 10% biocatalyst loading (w/w) in a fluidized bed reactor, allowing recycling of the biocatalyst up to five times. These results show promising potential for an industrial approach aimed at the biosynthesis of short-chain esters, namely for natural flavor and fragrance production in micro-aqueous media.

  14. Holographic interferometry of ultrasmall-pressure-induced curvature changes of bilayer lipid membranes

    SciTech Connect

    Picard, G.; Schneider-Henriquez, J.E.; Fendler, J.H. )

    1990-01-25

    Two-exposure interferometric holograms have been shown to sensitively report ultrasmall-pressure (10 natm)-induced curvature changes in glyceryl monooleate (GMO) bilayer lipid membranes (BLMs). The number of concentric fringes observed, and hence the lateral distance between the plane of the Teflon and the BLM, increased linearly with increasing transmembrane pressure and led to a value of 1.1 {plus minus} 0.05 dyn/cm for the surface tension of the BLM. BLMs with appreciable Plateau-Gibbs borders have been shown to undergo nonuniform deformation; the bilayer portion is distorted less than the surrounding Plateau-Gibbs border upon the application of a transmembrane pressure gradient.

  15. High-resolution proton nuclear magnetic resonance characterization of seminolipid from bovine spermatozoa.

    PubMed

    Alvarez, J G; Storey, B T; Hemling, M L; Grob, R L

    1990-06-01

    The high-resolution one- and two-dimensional proton nuclear magnetic resonance (1H-NMR) characterization of seminolipid from bovine spermatozoa is presented. The 1H-NMR data was confirmed by gas-liquid chromatography-mass spectrometric analysis of the partially methylated alditol acetates of the sugar unit, mild alkaline methanolysis of the glyceryl ester, mobility on normal phase and diphasic thin-layer chromatography (HPTLC), and fast atom bombardment mass spectrometry (FAB-MS). The structure of the molecule corresponds to 1-O-hexadecyl-2-O-hexadecanoyl-3-O-beta-D-(3'-sulfo)-galactopyranosyl- sn-glycerol.

  16. Enhancement effect of terpenes on silver sulphadiazine permeation through third-degree burn eschar.

    PubMed

    Moghimi, Hamid R; Makhmalzadeh, Behzad S; Manafi, Ali

    2009-12-01

    Antimicrobial therapy remains one of the most important methods of wound management. Systemically administered antimicrobials may not achieve therapeutic levels in wound and most agents cannot penetrate burn eschar well enough when applied topically. Therefore, we tested the notion to increase permeability of eschar toward topical agents using terpenes, a well-known class of skin permeation enhancers. Four terpenes, limonene (hydrocarbon), eucalyptol (ether), alpha-pinene oxide (epoxide) and geraniol (alcohol) were chosen and their effects on permeation of silver sulphadiazine (SSD), a widely used topical antimicrobial agent, through human third-degree burn eschar was evaluated using static diffusion cells. Results showed that terpenes increased permeation flux of SSD through eschar significantly (P<0.0001). Limonene provided the highest flux enhancement ratio (9.0 times), followed by geraniol, eucalyptol and alpha-pinene oxide with enhancement ratios of 5.5, 4.7 and 4.3 respectively. The effects of terpenes on permeation lag-time, was less than 20%. Data analysis revealed that terpenes increase permeation of SSD mainly by increasing its partitioning into the eschar. The present results show that permeation of drugs through burn eschar can be increased considerably by terpenes and that burn wound antimicrobial therapy may be improved by terpenes and possibly other penetration enhancers.

  17. Exocrine secretions of wheel bugs (Heteroptera: Reduviidae: Arilus spp.): clarification and chemistry.

    PubMed

    Aldrich, Jeffrey R; Chauhan, Kamlesh R; Zhang, Aijun; Zarbin, Paulo H G

    2013-01-01

    Wheel bugs (Heteroptera: Reduviidae: Harpactorinae: Arilus) are general predators, the females of which have reddish-orange subrectal glands (SGs) that are eversible like the osmeteria in some caterpillars. The rancid odor of Arilus and other reduviids actually comes from Brindley's glands, which in the North (A. cristatus) and South (A. carinatus) American wheel bugs studied emit similar blends of 2-methylpropanoic, butanoic, 3-methylbutanoic, and 2-methylbutanoic acids. The Arilus SG secretions studied here are absolutely species-specific. The volatile SG components of A. carinatus include (E)-2-octenal, (E)-2-nonenal, (E)-2-decenal, (E,E)-2,4-nonadienal, (E)-2-undecenal, hexanoic acid, 4-oxo-nonanal, (E,E)-2,4-decadienal, (E,Z)-2,4- or (Z,E)-2,4-decadienal, and 4-oxo-(E)-2-nonenal; whereas in A. cristatus the SG secretion contains beta-pinene, limonene, terpinolene, terpinen-4-ol, thymol methyl ether, alpha-terpineol, bornyl acetate, methyl eugenol, beta-caryophyllene, caryophyllene oxide, and farnesol. Arilus spp. SG secretions may be sex pheromones, but verification of this hypothesis requires further testing.

  18. Hydrolysis of triacetin catalyzed by immobilized lipases: effect of the immobilization protocol and experimental conditions on diacetin yield.

    PubMed

    Hernandez, Karel; Garcia-Verdugo, Eduardo; Porcar, Raul; Fernandez-Lafuente, Roberto

    2011-05-06

    The effect of the immobilization protocol and some experimental conditions (pH value and presence of acetonitrile) on the regioselective hydrolysis of triacetin to diacetin catalyzed by lipases has been studied. Lipase B from Candida antarctica (CALB) and lipase from Rhizomucor miehei (RML) were immobilized on Sepabeads (commercial available macroporous acrylic supports) activated with glutaraldehyde (covalent immobilization) or octadecyl groups (adsorption via interfacial activation). All the biocatalysts accumulated diacetin. Covalently immobilized RML was more active towards rac-methyl mandelate than the adsorbed RML. However, this covalent RML preparation presented the lowest activity towards triacetin. For this reason, this preparation was discarded as biocatalyst for this reaction. At pH 7, acyl migration occurred giving a mixture of 1,2 and 1,3 diacetin, but at pH 5.5, only 1,2 diacetin was produced. Yields were improved at acidic pH values and in the presence of 20% acetonitrile (to over 95%). RML immobilized on octadecyl Sepabeads was proposed as optimal preparation, mainly due to its higher specific activity. Each enzyme preparation presented very different properties. Moreover, changes in the reaction conditions affected the various immobilized enzymes in a different way.

  19. Functionalization of hybrid monolithic columns via thiol-ene click reaction for proteomics analysis.

    PubMed

    Liu, Zhongshan; Liu, Jing; Liu, Zheyi; Wang, Hongwei; Ou, Junjie; Ye, Mingliang; Zou, Hanfa

    2017-01-16

    The vinyl-functionalized hybrid monolithic columns (75 and 150μm i.d.) were prepared via sol-gel chemistry of tetramethoxysilane (TMOS) and vinyltrimethoxysilane (VTMS). The content of accessible vinyl groups was further improved after the monolithic column was post-treated with vinyldimethylethoxysilane (VDMES). The surface properties of monolithic columns were tailored via thiol-ene click reaction by using 1-octadecanethiol, sodium 3-mercapto-1-propanesulfonate and 2,2'-(ethylenedioxy)diethanethiol/vinylphosphonic acid, respectively. The preparing octadecyl-functionalized monolithic columns were adopted for proteomics analysis in cLC-MS/MS. A 37-cm-long×75-μm-i.d. monolithic column could identify 3918 unique peptides and 1067 unique proteins in the tryptic digest of proteins from HeLa cells. When a 90-cm-long×75-μm-i.d. monolithic column was used, the numbers of unique peptides and proteins were increased by 82% and 32%, respectively. Furthermore, strong cation exchange (SCX) monolithic columns (4cm in length×150μm i.d.) were also prepared and coupled with the 37-cm-long×75-μm-i.d. octadecyl-functionalized monolithic column for two-dimensional SCX-RPLC-MS/MS analysis, which could identify 17114 unique peptides and 3211 unique proteins.

  20. A continuous spectrophotometric assay that distinguishes between phospholipase A1 and A2 activities[S

    PubMed Central

    El Alaoui, Meddy; Soulère, Laurent; Noiriel, Alexandre; Popowycz, Florence; Khatib, Abdallah; Queneau, Yves; Abousalham, Abdelkarim

    2016-01-01

    A new spectrophotometric assay was developed to measure, continuously and specifically, phospholipase A1 (PLA1) or phospholipase A2 (PLA2) activities using synthetic glycerophosphatidylcholines (PCs) containing α-eleostearic acid, either at the sn-1 position [1-α-eleostearoyl-2-octadecyl-rac-glycero-3-phosphocholine (EOPC)] or at the sn-2 position [1-octadecyl-2-α-eleostearoyl-rac-glycero-3-phosphocholine (OEPC)]. The substrates were coated onto the wells of microtiter plates. A nonhydrolyzable ether bond, with a non-UV-absorbing alkyl chain, was introduced at the other sn position to prevent acyl chain migration during lipolysis. Upon enzyme action, α-eleostearic acid is liberated and then solubilized into the micellar phase. The PLA1 or PLA2 activity was measured by the increase in absorbance at 272 nm due to the transition of α-eleostearic acid from the adsorbed to the soluble state. EOPC and OEPC differentiate, with excellent accuracy, between PLA1 and PLA2 activity. Lecitase®, guinea pig pancreatic lipase-related protein 2 (known to be a PLA1 enzyme), bee venom PLA2, and porcine pancreatic PLA2 were all used to validate the assay. Compared with current assays used for continuously measuring PLA1 or PLA2 activities and/or their inhibitors, the development of this sensitive enzymatic method, using coated PC substrate analogs to natural lipids and based on the UV spectroscopic properties of α-eleostearic acid, is a significant improvement. PMID:27194811

  1. Aging and nonlinear rheology of thermoreversible colloidal gels

    NASA Astrophysics Data System (ADS)

    Wagner, Norman; Gordon, Melissa; Kloxin, Christopher

    Colloidal dispersions are found in a wide variety of consumer products such as paint, food and pharmaceuticals. We investigate gel formation and aging in a thermoreverible gel consisting of octadecyl-coated silica nanoparticles suspended in n-tetradecane. In this system, the octadecyl brush can undergo a phase change allowing the attractions between particles to be tuned by temperature (1,2). By probing the system with steady shear and large amplitude oscillatory shear, we have studied the effect of thermal history and shear history on gel formation and gel mechanical properties during aging. Gels were formed by approaching a common temperature from above and below to determine a reference state from which creep tests were conducted. Creep ringing was observed as expected for the viscoelastic gel. The rheological aging is interpreted in terms of the gel microstructure formed with differing thermal and shear histories to determine how processing affects structure. Recently proposed scaling laws for the rheology and structure under flow are explored within the context of gel aging (3). Through rheological and microstructural measurements, we will further the understanding of gel formation and aging in this model system which may be applied to processing conditions in an industrial setting.

  2. Effect of alkyl properties and head groups of cationic surfactants on retention of cesium by organoclays.

    PubMed

    Wang, Tsing-Hai; Hsieh, Chi-Jung; Lin, Shih-Min; Wu, Ding-Chiang; Li, Ming-Hsu; Teng, Shi-Ping

    2010-07-01

    Cationic surfactants modified clays exhibit high sorptive capability toward anionic radionuclides but retention of cationic radionuclides was concurrently reduced. In this study, organoclays were synthesized by intercalating a variety of primary/quaternary alkylammonium species (NH(2)R/(CH(3))(3)N(+)RBr(-), where R = benzyl, dodecyl, and octadecyl) into bentonite MX-80. The effect of surfactant's properties on enhancing or limiting cationic sorption capability was investigated by performing Cs sorption experiments. Experimental results were analyzed using the MINEQL+ software by considering Cs uptake by structural and edge sorption sites. Bentonites that were intercalated with primary alkylammonium surfactants had a higher sorptive capacity than those intercalated with quaternary alkylammonium surfactants. Samples intercalated with octadecyl-bearing surfactants had the lowest sorption rate. XRD and FTIR analyses revealed that each organoclay had a characteristic arrangement of alkyl chains. The cation retention of organoclays was dominated by the extent of hydrophobic interactions affected by the local distribution and arrangement of surfactants. The intercalated primary alkylammoniun surfactants tended to transform into local clusters with a high packing density, leaving more structural sites available for Cs uptake. In contrast, the NH(3)R(+)-surfactants tended to form a denser monolayer over clay surface, inhibiting the retention of Cs at structural sites.

  3. Bonded-phase extraction column isolation of organic compounds in groundwater at a hazardous waste site

    USGS Publications Warehouse

    Rostad, C.E.; Pereira, W.E.; Ratcliff, S.M.

    1984-01-01

    A procedure for isolation of hazardous organic compounds from water for gas chromatography/mass spectrometry analysis Is presented and applied to creosote- and pentachlorophenol-contaminated groundwater resulting from wood-treatment processes. This simple procedure involved passing a 50-100-mL sample through a bonded-phase extraction column, eluting the trapped organic compounds from the column with 2-4 mL of solvent, and evaporating the sample to 100 ??L with a stream of dry nitrogen, after which the sample was ready for gas chromatography/mass spectrometry analysis. Representative compounds indicative of creosote contamination were used for recovery and precision studies from the cyclohexyl-bonded phase. Recovery of these compounds from n-octyl-, n-octadecyl-, cyclohexyl-, and phenyl-bonded phases was compared. The bonded phase that exhibited the best recovery and least bias toward acidic or basic cmpounds was the n-octadecyl phase. Detailed compound Identification Is given for compounds Isolated from creosote- and pentachlorophenol-contaminated groundwater using the cyclohexyl-bonded phase.

  4. Bonded-phase extraction column isolation of organic compounds in groundwater at a hazardous waste site

    SciTech Connect

    Rostad, C.E.; Pereira, W.E.; Ratcliff, S.M.

    1984-12-01

    A procedure for isolation of hazardous organic compounds from water for gas chromatography/mass spectrometry analysis is presented and applied to creosote- and pentachlorophenol-contaminated groundwater resulting from wood-treatment processes. This simple procedure involved passing a 50-100 mL sample through a bonded-phase extraction column, eluting the trapped organic compounds from the column with 2-4 mL of solvent, and evaporating the sample to 100 micro-L with a stream of dry nitrogen, after which the sample was ready for gas chromatography/mass spectrometry analysis. Representative compounds indicative of creosote contamination were used for recovery and precision studies from the cyclohexyl-bonded phase. Recovery of these compounds from n-octyl-, n-octadecyl-, cyclohexyl-, and phenyl-bonded phases was compared. The bonded phase that exhibited the best recovery and least bias toward acidic or basic compounds was the n-octadecyl phase. Detailed compound identification is given for compounds isolated from creosote- and pentrachlorophenol-contaminated groundwater using the cyclohexyl-bonded phase. 12 references, 1 figure, 4 tables.

  5. Preparation of 4-butylaniline-bonded silica gel for the solid-phase extraction of flavone glycosides.

    PubMed

    Chu, Ganghui; Cai, Wensheng; Shao, Xueguang

    2015-04-01

    To extract flavone glycosides efficiently, a new extraction material based on 4-butylaniline-bonded silica gel was prepared using a two-step grafting method including a ring-opening reaction and synchronous hydrolysis. Preparation of the silica-based material was easily achieved under mild conditions, and the material was characterized by Fourier transform infrared spectroscopy, elemental analysis, and scanning electron microscopy. The material was used in solid-phase extraction, and the extraction can be performed in neutral conditions without regard to ionic strength. Selectivity tests of 14 compounds on the extraction cartridge showed that the material has a high affinity to flavone glycosides in contrast to octadecyl silica, and the extraction yields for four flavone glycosides were found to be >93%. Selectivity tests further reveal that the adsorption on its surface is likely attributed to multiple interactions, including hydrophobic interactions, π-π interactions, and hydrogen bonding. To explore the applicability of 4-butylaniline-bonded silica gel, naringin and hesperidin from Simotang oral liquid were extracted, and the extraction yields were >90%, which is distinguished from <28% on octadecyl silica cartridge.

  6. Tribology of monolayer films: comparison between n-alkanethiols on gold and n-alkyl trichlorosilanes on silicon.

    PubMed

    Booth, Brandon D; Vilt, Steven G; McCabe, Clare; Jennings, G Kane

    2009-09-01

    This Article presents a quantitative comparison of the frictional performance for monolayers derived from n-alkanethiolates on gold and n-alkyl trichlorosilanes on silicon. Monolayers were characterized by pin-on-disk tribometry, contact angle analysis, ellipsometry, and electrochemical impedance spectroscopy (EIS). Pin-on-disk microtribometry provided frictional analysis at applied normal loads from 10 to 1000 mN at a speed of 0.1 mm/s. At low loads (10 mN), methyl-terminated n-alkanethiolate self-assembled monolayers (SAMs) exhibited a 3-fold improvement in coefficient of friction over SAMs with hydroxyl- or carboxylic-acid-terminated surfaces. For monolayers prepared from both n-alkanethiols on gold and n-alkyl trichlorosilanes on silicon, a critical chain length of at least eight carbons is required for beneficial tribological performance at an applied load of 9.8 mN. Evidence for disruption of chemisorbed alkanethiolate SAMs with chain lengths n octadecyl dimethylchlorosilane and n-octadecyl trichlorosilane withstood normal loads at least 30 times larger than those that damaged octadecanethiolate SAMs. Collectively, our results show that the tribological properties of monolayer films are dependent on their internal stabilities, which are influenced by cohesive chain interactions (van der Waals) and the adsorbate-substrate bond.

  7. Nitric oxide-mediated cyclooxygenase activation. A key event in the antiplatelet effects of nitrovasodilators.

    PubMed Central

    Salvemini, D; Currie, M G; Mollace, V

    1996-01-01

    We have evaluated the contributions of nitric oxide (NO) and prostacyclin (PGI2) in the in vivo antiplatelet effects of clinically useful nitrovasodilators. In rats, intravenous infusion of three NO donors, glyceryl trinitrate, sodium nitroprusside, or 3'-morpholinosydnonimine, the stable metabolite of molsidomine, released 6-keto PGF1alpha (the stable metabolite of PGI2) and inhibited ex vivo human platelet aggregation to adenosine diphosphate by at least 80%. In in vitro studies, glyceryl trinitrate, sodium nitroprusside, and 3'-morpholinosydnonimine, at clinically attainable concentrations, increased cyclooxygenase activity in endothelial cells (EC), which resulted in a four- to sixfold release of 6-keto PGF1alpha. Pretreatment of the EC with hemoglobin which binds to and inactivates the biological actions of NO, but not by methylene blue (MelB), attenuated the NO-mediated PGI2 from the EC by at least 70%. Release of 6-keto PGF1alpha by the NO donors increased the ability of these compounds to inhibit thrombin-induced human platelet aggregation by at least 10 times; this potentiation was inhibited by hemoglobin but not by MeB. MeB blocked the direct anti-platelet effect of the NO donors in the absence of EC. In summary, we have demonstrated that NO, directly as well as together with an NO-driven cyclooxygenase activation (and hence PGI2), release contributes to the marked anti-platelet effects observed after the in vivo administration of clinically used nitrovasodilators. PMID:8647949

  8. Nanosized self-emulsifying lipid vesicles of diacylglycerol-PEG lipid conjugates: Biophysical characterization and inclusion of lipophilic dietary supplements

    SciTech Connect

    Koynova, Rumiana; Tihova, Mariana

    2010-04-12

    Hydrated diacylglycerol-PEG lipid conjugates, glyceryl dioleate-PEG12 (GDO-PEG12) and glyceryl dipalmitate-PEG23 (GDP-PEG23), spontaneously form uni- or oligolamellar liposomes in their liquid crystalline phase, in distinct difference from the PEGylated phospholipids which form micelles. GDP-PEG23 exhibits peculiar hysteretic phase behavior and can arrange into a long-living hexagonal phase at ambient and physiological temperatures. Liposomes of GDO-PEG12 and its mixture with soy lecithin exchange lipids with the membranes much more actively than common lecithin liposomes; such an active lipid exchange might facilitate the discharging of the liposome cargo upon uptake and internalization, and can thus be important in drug delivery applications. Diacylglycerol-PEG lipid liposome formulations can encapsulate up to 20-30 wt.% lipophilic dietary supplements such as fish oil, coenzyme Q10, and vitamins D and E. The encapsulation is feasible by way of dry mixing, avoiding the use of organic solvent.

  9. Safety Evaluation of Polyethylene Glycol (PEG) Compounds for Cosmetic Use

    PubMed Central

    Shin, Chan Young; Kim, Kyu-Bong

    2015-01-01

    Polyethylene glycols (PEGs) are products of condensed ethylene oxide and water that can have various derivatives and functions. Since many PEG types are hydrophilic, they are favorably used as penetration enhancers, especially in topical dermatological preparations. PEGs, together with their typically nonionic derivatives, are broadly utilized in cosmetic products as surfactants, emulsifiers, cleansing agents, humectants, and skin conditioners. The compounds studied in this review include PEG/PPG-17/6 copolymer, PEG-20 glyceryl triisostearate, PEG-40 hydrogenated castor oil, and PEG-60 hydrogenated castor oil. Overall, much of the data available in this review are on PEGylated oils (PEG-40 and PEG-60 hydrogenated castor oils), which were recommended as safe for use in cosmetics up to 100% concentration. Currently, PEG-20 glyceryl triisostearate and PEGylated oils are considered safe for cosmetic use according to the results of relevant studies. Additionally, PEG/PPG-17/6 copolymer should be further studied to ensure its safety as a cosmetic ingredient. PMID:26191379

  10. Microbial diversity of cold-seep sediments in Sagami Bay, Japan, as determined by 16S rRNA gene and lipid analyses.

    PubMed

    Fang, Jiasong; Shizuka, Arakawa; Kato, Chiaki; Schouten, Stefan

    2006-09-01

    Microbial communities in Calyptogena sediment and microbial mats of Sagami Bay, Japan, were characterized using 16S rRNA gene sequencing and lipid biomarker analysis. Characterization of 16S rRNA gene isolated from these samples suggested a predominance of bacterial phylotypes related to Gammaproteobacteria (57-64%) and Deltaproteobacteria (27-29%). The Epsilonproteobacteria commonly found in cold seeps and hydrothermal vents were only detected in the microbial mat sample. Significantly different archaeal phylotypes were found in Calyptogena sediment and microbial mats; the former contained only Crenarchaeota clones (100% of the total archaeal clones) and the latter exclusively Euryarchaeota clones, including the anaerobic oxidation of methane archaeal groups ANME-2a and ANME-2c. Many of these lineages are as yet uncultured and undescribed groups of bacteria and archaea. Phospholipid fatty acid analysis suggested the presence of sulphate-reducing and sulphur-oxidizing bacteria. Results of intact glyceryl dialkyl glyceryl tetraether lipid analysis indicated the presence of nonthermophilic marine planktonic archaea. These results suggest that the microbial community in the Sagami Bay seep site is distinct from previously characterized cold-seep environments.

  11. Release of Methane from Bering Sea Sediments During the Last Glacial Period

    SciTech Connect

    Mea Cook; Lloyd Keigwin

    2007-11-30

    Several lines of evidence suggest that during times of elevated methane flux the sulfate-methane transition zone (SMTZ) was positioned near the sediment-water interface. We studied two cores (from 700 m and 1457 m water depth) from the Umnak Plateau region. Anomalously low d13C and high d18O in benthic and planktonic foraminifera in these cores are the consequence of diagenetic overgrowths of authigenic carbonates. There are multiple layers of authigenic-carbonate-rich sediment in these cores, and the stable isotope compositions of the carbonates are consistent with those formed during anaerobic oxidation of methane (AOM). The carbonate-rich layers are associated with biomarkers produced by methane-oxidizing archaea, archaeol and glyceryl dibiphytanyl glyceryl tetraether (GDGT). The d13C of the archaeol and certain GDGTs are isotopically depleted. These carbonate- and AOM-biomarker-rich layers were emplaced in the SMTZ during episodes when there was a high flux of methane or methane-rich fluids upward in the sediment column. The sediment methane in the Umnak Plateau region appears to have been very dynamic during the glacial period, and interacted with the ocean-atmosphere system at millennial time scales. The upper-most carbonate-rich layers are in radiocarbon-dated sediment deposited during interstitials 2 and 3, 28-20 ka, and may be associated with the climate warming during this time.

  12. Microbial Diversity of Cold-Seep Sediments in Sagami Bay, Japan as Determined by 16S rDNA and Lipid Analyses

    NASA Astrophysics Data System (ADS)

    Fang, J.; Arakawa, S.; Kato, C.; Schouten, S.

    2006-12-01

    Microbial communities in Calyptogena sediment and microbial mats of Sagami Bay, Japan were characterized by using 16S rDNA sequencing and lipid biomarker analysis. Characterization of 16S rDNA isolated from these samples suggested a predominance of bacterial phylotypes related to γ- (57-64%) and δ-subclasses (27-29%) of the Proteobacteria. The ɛ-subclass of the Proteobacteria commonly found in cold seeps and hydrothermal vents were only detected in the microbial mat sample. There are significantly different archaeal phylotypes between Calyptogena sediment and microbial mat; the former contains only Crenarchaeota clones (100% of the total archaeal clones) and the latter exclusively Euryarchaeota clones including the ANME-2a and ANME-2c archaeal groups. Many of these lineages are as yet uncultured and undescribed groups of bacteria and archaea. Phospholipid fatty acid analysis suggests the presence of sulfate-reducing and sulfur-oxidizing bacteria. Results of intact glyceryl dialkyl glyceryl tetraether (GDGT) lipid analysis indicate the presence of nonthermophilic marine planktonic archaea. These results suggest that the microbial community in the Sagami Bay seep site is distinct from previously characterized cold seep environments.

  13. Oral L-arginine improves endothelium-dependent dilation in hypercholesterolemic young adults.

    PubMed Central

    Clarkson, P; Adams, M R; Powe, A J; Donald, A E; McCredie, R; Robinson, J; McCarthy, S N; Keech, A; Celermajer, D S; Deanfield, J E

    1996-01-01

    In hypercholesterolemic rabbits, oral L-arginine (the substrate for endothelium derived nitric oxide) attenuates endothelial dysfunction and atheroma formation, but the effect in hypercholesterolemic humans is unknown. Using high resolution external ultrasound, we studied arterial physiology in 27 hypercholesterolemic subjects aged 29+/-5 (19-40) years, with known endothelial dysfunction and LDL-cholesterol levels of 238+/-43 mg/dl. Each subject was studied before and after 4 wk of L-arginine (7 grams x 3/day) or placebo powder, with 4 wk washout, in a randomized double-blind crossover study. Brachial artery diameter was measured at rest, during increased flow (causing endothelium-dependent dilation, EDD) and after sublingual glyceryl trinitrate (causing endothelium-independent dilation). After oral L-arginine, plasma L-arginine levels rose from 115+/-103 to 231+/-125 micromol/liter (P<0.001), and EDD improved from 1.7+/-1.3 to 5.6+/-3.0% (P<0.001). In contrast there was no significant change in response to glyceryl trinitrate. After placebo there were no changes in endothelium-dependent or independent vascular responses. Lipid levels were unchanged after L-arginine and placebo. Dietary supplementation with L-arginine significantly improves EDD in hypercholesterolemic young adults, and this may impact favorably on the atherogenic process. PMID:8621785

  14. Fatty Acid Ethyl Esters Are Less Toxic Than Their Parent Fatty Acids Generated during Acute Pancreatitis

    PubMed Central

    Patel, Krutika; Durgampudi, Chandra; Noel, Pawan; Trivedi, Ram N.; de Oliveira, Cristiane; Singh, Vijay P.

    2017-01-01

    Although ethanol causes acute pancreatitis (AP) and lipolytic fatty acid (FA) generation worsens AP, the contribution of ethanol metabolites of FAs, ie, FA ethyl esters (FAEEs), to AP outcomes is unclear. Previously, pancreata of dying alcoholics and pancreatic necrosis in severe AP, respectively, showed high FAEEs and FAs, with oleic acid (OA) and its ethyl esters being the most abundant. We thus compared the toxicities of FAEEs and their parent FAs in severe AP. Pancreatic acini and peripheral blood mononuclear cells were exposed to FAs or FAEEs in vitro. The triglyceride of OA (i.e., glyceryl tri-oleate) or OAEE was injected into the pancreatic ducts of rats, and local and systemic severities were studied. Unsaturated FAs at equimolar concentrations to FAEEs induced a larger increase in cytosolic calcium, mitochondrial depolarization, and necro-apoptotic cell death. Glyceryl tri-oleate but not OAEE resulted in 70% mortality with increased serum OA, a severe inflammatory response, worse pancreatic necrosis, and multisystem organ failure. Our data show that FAs are more likely to worsen AP than FAEEs. Our observations correlate well with the high pancreatic FAEE concentrations in alcoholics without pancreatitis and high FA concentrations in pancreatic necrosis. Thus, conversion of FAs to FAEE may ameliorate AP in alcoholics. PMID:26878214

  15. Graphene as a photothermal actuator for control of lipid mesophase structure.

    PubMed

    Quinn, Matthew D J; Wang, Tao; Du, Joanne D; Boyd, Ben J; Hawley, Adrian; Notley, Shannon M

    2017-01-07

    The optical density of pristine graphene is high and broad in the near infrared region of the electromagnetic spectrum positioning this material as a highly efficient photothermal agent for in vivo applications. In this study, surfactant assisted exfoliated graphene was incorporated within bulk lipid samples of varying lipid types: glyceryl monoether, glyceryl monooleate and phytantriol. The pristine graphene sheets did not disrupt the packing of the liquid crystals while being in sufficiently intimate contact to provide localized heating and induce phase transitions. The phase progressions induced through heating using NIR irradiation of the entrained graphene particles within the bulk liquid crystal were studied using SAXS and confirmed using polarized optical microscopy. Increases in apparent temperature experienced by the matrix of up to 50 °C were observed by establishing a SAXS versus bulk temperature calibration curve allowing in situ measurements. The studies demonstrate the potential for use of graphene as a photothermal actuator across a range of lipid based systems of interest in controlled drug delivery.

  16. Effect of Antiadherents on the Physical and Drug Release Properties of Acrylic Polymeric Films.

    PubMed

    Ammar, Hussein O; Ghorab, Mamdouh M; Felton, Linda A; Gad, Shadeed; Fouly, Aya A

    2016-06-01

    Antiadherents are used to decrease tackiness of a polymer coating during both processing and subsequent storage. Despite being a common excipient in coating formulae, antiadherents may affect mechanical properties of the coating film as well as drug release from film-coated tablets, but how could addition of antiadherents affect these properties and to what extent and is there a relation between the physical characteristics of the tablet coat and the drug release mechanisms? The aim of this study was to evaluate physical characteristics of films containing different amounts of the antiadherents talc, glyceryl monostearate, and PlasACRYL(TM) T20. Eudragit RL30D and Eudragit RS30D as sustained release polymers and Eudragit FS30D as a delayed release material were used. Polymer films were characterized by tensile testing, differential scanning calorimetry (DSC), microscopic examination, and water content as calculated from loss on drying. The effect of antiadherents on in vitro drug release for the model acetylsalicylic acid tablets coated with Eudragit FS30D was also determined. Increasing talc concentration was found to decrease the ability of the polymer films to resist mechanical stress. In contrast, glyceryl monostearate (GMS) and PlasACRYL produced more elastic films. Talc at concentrations higher than 25% caused negative effects, which make 25% concentration recommended to be used with acrylic polymers. All antiadherents delayed the drug release at all coating levels; hence, different tailoring of drug release may be achieved by adjusting antiadherent concentration with coating level.

  17. An evaluation of acute hydrogen sulfide poisoning in rats through serum metabolomics based on gas chromatography-mass spectrometry.

    PubMed

    Zhang, Meiling; Deng, Mingjie; Ma, Jianshe; Wang, Xianqin

    2014-01-01

    Hydrogen sulfide (H2S) is the second leading cause of toxin-related deaths in the operational site. Its main target organs of toxic effects are the central nervous system and respiratory system. In this study, we developed a serum metabonomic method, based on gas chromatography-mass spectrometry (GC/MS), to evaluate the effect of acute poisoning by hydrogen sulfide on rats. Pattern recognition analysis, including both principal component analysis (PCA) and partial least squares-discriminate analysis (PLS-DA), revealed that acute hydrogen sulfide poisoning induced metabolic perturbations. Compared to the control group, the level of urea, glucose, glyceryl stearate in rat serum of the poisoning group increased after two hours, and the level of glucose, docosahexaenoic acid, glyceryl stearate and arachidonic acid in rat serum of the poisoning group increased after 48 h, while the L-valine, galactose, L-tyrosine levels decreased. Our results indicate that metabonomic methods based on GC/MS may be useful to elucidate acute hydrogen sulfide poisoning through the exploration of biomarkers.

  18. The Japan Flavour and Fragrance Materials Association's (JFFMA) safety assessment of acetal food flavouring substances uniquely used in Japan.

    PubMed

    Okamura, Hiroyuki; Abe, Hajime; Hasegawa-Baba, Yasuko; Saito, Kenji; Sekiya, Fumiko; Hayashi, Shim-Mo; Mirokuji, Yoshiharu; Maruyama, Shinpei; Ono, Atsushi; Nakajima, Madoka; Degawa, Masakuni; Ozawa, Shogo; Shibutani, Makoto; Maitani, Tamio

    2015-01-01

    Using the procedure devised by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), we performed safety evaluations on five acetal flavouring substances uniquely used in Japan: acetaldehyde 2,3-butanediol acetal, acetoin dimethyl acetal, hexanal dibutyl acetal, hexanal glyceryl acetal and 4-methyl-2-pentanone propyleneglycol acetal. As no genotoxicity study data were available in the literature, all five substances had no chemical structural alerts predicting genotoxicity. Using Cramer's classification, acetoin dimethyl acetal and hexanal dibutyl acetal were categorised as class I, and acetaldehyde 2,3-butanediol acetal, hexanal glyceryl acetal and 4-methyl-2-pentanone propyleneglycol acetal as class III. The estimated daily intakes for all five substances were within the range of 1.45-6.53 µg/person/day using the method of maximised survey-derived intake based on the annual production data in Japan from 2001, 2005, 2008 and 2010, and 156-720 µg/person/day using the single-portion exposure technique (SPET), based on the average use levels in standard portion sizes of flavoured foods. The daily intakes of the two class I substances were below the threshold of toxicological concern (TTC) - 1800 μg/person/day. The daily intakes of the three class III substances exceeded the TTC (90 μg/person/day). Two of these, acetaldehyde 2,3-butanediol acetal and hexanal glyceryl acetal, were expected to be metabolised into endogenous products after ingestion. For 4-methyl-2-pentanone propyleneglycol acetal, one of its metabolites was not expected to be metabolised into endogenous products. However, its daily intake level, based on the estimated intake calculated by the SPET method, was about 1/15 000th of the no observed effect level. It was thus concluded that all five substances raised no safety concerns when used for flavouring foods at the currently estimated intake levels. While no information on in vitro and in vivo toxicity for all five substances was available

  19. Development of terbinafine solid lipid nanoparticles as a topical delivery system

    PubMed Central

    Chen, Ying-Chen; Liu, Der-Zen; Liu, Jun-Jen; Chang, Tsung-Wei; Ho, Hsiu-O; Sheu, Ming-Thau

    2012-01-01

    To resolve problems of long treatment durations and frequent administration of the antifungal agent terbinafine (TB), solid lipid nanoparticles (SLNs) with the ability to load lipophilic drugs and nanosize were developed. The SLNs were manufactured by a microemulsion technique in which glyceryl monostearate (GMS), glyceryl behenate (Compritol® 888; Gattefossé), and glyceryl palmitostearate (Precirol® ATO 5; Gattefossé) were used as the solid lipid phases, Tween® and Cremophor® series as the surfactants, and propylene glycol as the cosurfactant to construct ternary phase diagrams. The skin of nude mice was used as a barrier membrane, and penetration levels of TB of the designed formulations and a commercial product, Lamisil® Once™ (Novartis Pharmaceuticals), in the stratum corneum (SC), viable epidermis, and dermis were measured; particle sizes were determined as an indicator of stability. The optimal SLN system contained a <5% lipid phase and >50% water phase. The addition of ethanol or etchants had no significant effect on enhancing the amount of TB that penetrated the skin layers, but it was enhanced by increasing the percentage of the lipid phase. Furthermore, the combination of GMS and Compritol® 888 was able to increase the stable amount of TB that penetrated all skin layers. For the ACP1-GM1 (4% lipid phase; Compritol® 888: GMS of 1:1) formulation, the amount of TB that penetrated the SC was similar to that of Lamisil® Once™, whereas the amount of TB of the dermis was higher than that of Lamisil® Once™ at 12 hours, and it was almost the same as that of Lamisil® Once™ at 24 hours. It was concluded that the application of ACP1-GM1 for 12 hours might have an efficacy comparable to that of Lamisil® Once™ for 24 hours, which would resolve the practical problem of the longer administration period that is necessary for Lamisil® Once™. PMID:22923986

  20. Polyelectrolyte gels comprising a lipophilic, cost-effective aluminate as fluorine-free absorbents for chlorinated hydrocarbons and diesel fuel.

    PubMed

    Wrede, Michael; Ganza, Viktoria; Bucher, Janina; Straub, Bernd F

    2012-07-25

    Superabsorbent polymers comprising a lipophilic, halogen-free, and cost-effective aluminate ("altebate") anion have been synthesized. The polyelectrolytes are based on octadecyl acrylate monomers, 0.8-1 mol % ethylene dimethacrylate cross-linker, and 5 mol % N-3-acroyloxypropyl trialkylammonium altebate. At 30 °C, swelling degrees of 70 (chlorobenzene), 102 (CHCl3), 130 (THF), 163 (ClCH2CH2Cl), 171 (dichlorobenzene), and 208 (CH2Cl2) have been determined. The polyelectrolyte absorbs reversibly diesel fuel with a swelling degree of 34, even in the presence of water. Swelling times and critical swelling temperatures have also been determined. The challenges for the development of oil absorbents are discussed.

  1. Comprehensive hydrophilic interaction and ion-pair reversed-phase liquid chromatography for analysis of di- to deca-oligonucleotides.

    PubMed

    Li, Qin; Lynen, Frédéric; Wang, Jian; Li, Hanlin; Xu, Guowang; Sandra, Pat

    2012-09-14

    A comprehensive two-dimensional HPLC approach with a high degree of orthogonality was developed for analysis of di- to deca-oligonucleotides (ONs). Hydrophilic interaction liquid chromatography (HILIC) was used in the first dimension, and ion-pair reversed-phase liquid chromatography (IP-RPLC) was employed in the second dimension. The two dimensions were connected via a ten-port valve interface equipped with octadecyl silica (ODS) traps to immobilize and focus the ONs eluting from the first dimension prior to IP-RPLC separation. An aqueous make-up flow was used for effective trapping. The comprehensive two-dimensional HPLC system was optimized with a mixture consisting of 27 oligonucleotide standards. An overall chromatographic peak capacity of 500 was obtained. The use of the volatile buffer triethylamine acetate in the second dimension allowed straightforward coupling to electrospray ionization mass spectrometry (ESI-MS) and detection of each ON in the negative ionization mode.

  2. Chromatographic behavior of small organic compounds in low-temperature high-performance liquid chromatography using liquid carbon dioxide as the mobile phase.

    PubMed

    Motono, Tomohiro; Nagai, Takashi; Kitagawa, Shinya; Ohtani, Hajime

    2015-07-01

    Low-temperature high-performance liquid chromatography, in which a loop injector, column, and detection cell were refrigerated at -35ºC, using liquid carbon dioxide as the mobile phase was developed. Small organic compounds (polyaromatic hydrocarbons, alkylbenzenes, and quinones) were separated by low-temperature high-performance liquid chromatography at temperatures from -35 to -5ºC. The combination of liquid carbon dioxide mobile phase with an octadecyl-silica (C18 ) column provided reversed phase mode separation, and a bare silica-gel column resulted in normal phase mode separation. In both the cases, nonlinear behavior at approximately -15ºC was found in the relationship between the temperature and the retention factors of the analytes (van't Hoff plots). In contrast to general trends in high-performance liquid chromatography, the decrease in temperature enhanced the separation efficiency of both the columns.

  3. [Determination of histamine in fish and fish products by tandem solid-phase extraction].

    PubMed

    Awazu, Kaoru; Nomura, Chie; Yamaguchi, Mizuka; Obana, Hirotaka

    2011-01-01

    A simple and practical method was developed for the determination of histamine in fish and fish products by solid-phase extraction and fluorescence derivatization. Histamine was extracted with trichloroacetic acid. The extract was neutralized and diluted with phosphate buffer (pH 6.8), and cleaned up with a tandem-connected octadecyl silica (ODS) and strong cation exchange silica (SCX) cartridge. After removal of the solvent, histamine was derivatized with fluorescamine and analyzed by ion-paired reversed-phase high-performance liquid chromatography with fluorescence detection. Recovery tests of histamine from six kinds of fish and fish products showed acceptable recovery (83-92%) with low relative standard deviation (less than 5%). This method could be useful for determination of histamine in fish.

  4. Thermodynamics of sorption of 1,3,4-oxadiazoles and 1,2,4,5-tetrazines according to reversed phase high-performance liquid chromatography

    NASA Astrophysics Data System (ADS)

    Saifutdinov, B. R.; Kurbatova, S. V.; Emel'Yanova, N. S.

    2010-04-01

    The thermodynamics of sorption of several 1,3,4-oxadiazoles and 1,2,4,5-tetrazines on octadecyl silica gel from aqueous acetonitrile solutions of different compositions has been studied. The thermodynamic characteristics of the chromatographic systems under study were calculated. The dependences of the standard molar change in the entropy term of the dependence ln k-1/ T and the enthalpy after the transfer of the sorbate from bulk solution to the surface layer on the content of the organic component in the eluent were analyzed for the compounds. It was shown that the structure of sorbate molecules affected the thermodynamic characteristics of their quasichemical sorption and solvation. Tendencies of compensation were found for sorption and solvation of the heterocyclic compounds under study.

  5. Molecular dynamics simulations of phosphonic acid-aluminum oxide self-organization and their evolution into ordered monolayers.

    PubMed

    Dietrich, H; Schmaltz, T; Halik, M; Zahn, D

    2017-02-15

    We outline an unprejudiced molecular dynamics simulation approach to study the mechanisms of self-organization encompassing the evolution of surfactant-surface interactions to the growth of self-assembled monolayers (SAMs). Therein, the time-length scale problem is tackled by combining an efficient docking-type procedure for implementing surfactant-by-surfactant association with detailed molecular simulations to explore structural relaxation. For this, nanosecond-scale molecular dynamics simulations unravel ordering processes during the gradual assembly of the monolayer. Along this line, different packing motifs of octadecyl phosphonic acid (ODPA) on the (0001) surface of α-alumina and implications for the final density and ordering of the resulting monolayers are elucidated. Moreover, the role of the solvent is discriminated by comparing SAM formation in 2-propanol, hexane and in a vacuum.

  6. Determination of steroidal glycosides in Yucca gloriosa flowers by LC/MS/MS.

    PubMed

    Montoro, Paola; Skhirtladze, Alexandre; Perrone, Angela; Benidze, Mariam; Kemertelidze, Ether; Piacente, Sonia

    2010-09-05

    An high-performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS/MS) method, was developed for the quantitative analysis of the steroidal glycosides occurring in Yucca gloriosa flowers. The HPLC experiments were performed by means of an octadecyl-modified reversed-phase C-18 column and a binary mobile phase system under gradient elution conditions. The fragmentation patterns of steroidal saponins were analyzed by ESI-MS(n) in positive ion mode and a specific multiple reaction monitoring MS/MS detection was developed for their quantitative determination. The described method provides high sensitivity and specificity for quantitative determination of the steroidal glycosides in Y. gloriosa flowers. Quantification was performed against an external calibration line obtained using each pure steroidal glycoside. Short- and long-term repeatabilities of the methods were better than 3 and 6%, respectively. The method was validated according to EMEA guidelines and applied to real samples.

  7. Dynamics of exosome internalization and trafficking.

    PubMed

    Tian, Tian; Zhu, Yan-Liang; Hu, Fei-Hu; Wang, Yuan-Yuan; Huang, Ning-Ping; Xiao, Zhong-Dang

    2013-07-01

    Cells release exosomes into extracellular medium. Although the important roles of exosomes in many physiological and pathological processes are being revealed, the mechanism of exosome-cell interaction remains unclear. In this article, employing real-time fluorescence microscopy, the motion of exosomes on the plasma membrane or in the cytoplasm of recipient PC12 cells was observed directly. In addition, several motion modes of exosomes were revealed by single particle tracking (SPT). The changes between motion modes were also detected, presenting the dynamic courses of exosome attachment onto plasma membrane and exosome uptake. Octadecyl rhodamine B chloride (R18) was found to be useful to distinguish endocytosis from fusion during exosome uptake. Colocalization with organelle markers showed exosomes were sorted to acidic vesicles after internalization. The results provide new sight into the exosome-cell interaction mode and the intercellular trafficking of exosomes. This study will help to understand the roles of exosomes at cell level.

  8. Bacteria-mimicking nanoparticle surface functionalization with targeting motifs

    NASA Astrophysics Data System (ADS)

    Lai, Mei-Hsiu; Clay, Nicholas E.; Kim, Dong Hyun; Kong, Hyunjoon

    2015-04-01

    In recent years, surface modification of nanocarriers with targeting motifs has been explored to modulate delivery of various diagnostic, sensing and therapeutic molecular cargo to desired sites of interest in in vitro bioengineering platforms and in vivo pathologic tissue. However, most surface functionalization approaches are often plagued by complex chemical modifications and effortful purifications. To resolve such challenges, this study demonstrates a unique method to immobilize antibodies that can act as targeting motifs on the surfaces of nanocarriers, inspired by a process that bacteria use for immobilization of the host's antibodies. We hypothesized that alkylated Staphylococcus aureus protein A (SpA) would self-assemble with micelles and subsequently induce stable coupling of antibodies to the micelles. We examined this hypothesis by using poly(2-hydroxyethyl-co-octadecyl aspartamide) (PHEA-g-C18) as a model polymer to form micelles. The self-assembly between the micelles and alkylated SpA became more thermodynamically favorable by increasing the degree of substitution of octadecyl chains to PHEA-g-C18, due to a positive entropy change. Lastly, the mixing of SpA-PA-coupled micelles with antibodies resulted in the coating of micelles with antibodies, as confirmed with a fluorescence resonance energy transfer (FRET) assay. The micelles coated with antibodies to VCAM-1 or integrin αv displayed a higher binding affinity to substrates coated with VCAM-1 and integrin αvβ3, respectively, than other controls, as evaluated with surface plasmon resonance (SPR) spectroscopy and a circulation-simulating flow chamber. We envisage that this bacteria-inspired protein immobilization approach will be useful to improve the quality of targeted delivery of nanoparticles, and can be extended to modify the surface of a wide array of nanocarriers.In recent years, surface modification of nanocarriers with targeting motifs has been explored to modulate delivery of various

  9. Decoration of silicon nanostructures with copper particles for simultaneous selective capture and mass spectrometry detection of His-tagged model peptide.

    PubMed

    Coffinier, Yannick; Kurylo, Ievgen; Drobecq, Hervé; Szunerits, Sabine; Melnyk, Oleg; Zaitsev, Vladimir N; Boukherroub, Rabah

    2014-10-21

    We present in this work a simple and fast preparation method of a new affinity surface-assisted laser/desorption ionization mass spectrometry (SALDI-MS) substrate based on silicon nanostructures decorated with copper particles. The silicon nanostructures were fabricated by the metal-assisted chemical etching (MACE) method. Then, superhydrophilic areas surrounded by superhydrophobic regions were formed through hydrosilylation reaction of 1-octadecene, followed by local degradation of the octadecyl layer. After that, copper particles were deposited in the hydrophilic areas by using the electroless method. We have demonstrated that these surfaces were able to perform high selective capture of model His-tag peptide even in a complex mixture such as serum solution. Then, the captured peptide was detected by mass spectrometry at a femtomolar level without the need of organic matrix.

  10. Determination of growth hormone-releasing hexapeptide by reversed-phase high-performance liquid chromatography with electrochemical detection.

    PubMed

    Choi, S J; Lee, H Y; Kim, S B; Kim, J H; Lee, S S; Yoo, S D; Lee, K C; Lee, H S

    2001-04-25

    A novel HPLC method with electrochemical detection is described for the determination of a growth-hormone-releasing hexapeptide (GHRP-6). HPLC conditions, such as the column, mobile phase, and oxidation potential, were optimized for sensitivity and selectivity of analysis. GHRP-6 was separated on a reversed-phase CN column with 37% acetonitrile in 100 mM phosphate buffer (pH 7.0) as the mobile phase. The optimum electrochemical oxidation signal was obtained at 0.85 V vs. Ag/AgCl in a glassy carbon working electrode due to two electroactive tryptophans and a histidine residue. Solid-phase extraction using octadecyl cartridges was optimized for sample cleanup of GHRP-6 from serum samples and the method was successfully applied over the concentration range of 5 to 100 ng/ml of analyte. reserved.

  11. One-Pot Synthesis of Organic-Sulfur-Zinc Hybrid Materials via Polycondensation of a Zinc Salt and Thiols Generated in Situ from Cyclic Dithiocarbonates.

    PubMed

    Ochiai, Bungo; Konta, Hirohisa

    2015-08-17

    Soluble organic-sulfur-zinc hybrid polymers were prepared via a one-pot reaction consisting of ring-opening addition and subsequent polycondensation. The first reaction is the nucleophilic ring-opening addition of 2-ethylhexylamine to multifunctional cyclic dithiocarbonates giving multiple thiols in situ. The sequential polycondensation of the in situ generated thiols with Zn(OAc)2 gave the target hybrid polymers. This one-pot method enabled the use of a shorter amine than the previous polycondensation of Zn(OAc)2 and purified thiols, which required octadecylamine to obtain a soluble product. The obtained hybrid polymers may be cast as composite films with polystyrene and poly(methyl methacrylate). Owing to the shorter alkyl chain, the calculated nD values of the products (1.60 or 1.61) are higher than that of the previous product bearing octadecyl chains (1.53).

  12. Infrared and Raman spectroscopic characterization of some organic substituted hybrid silicas.

    PubMed

    Capeletti, Larissa B; Baibich, Ione M; Butler, Ian S; dos Santos, João H Z

    2014-12-10

    Nine hybrid silicas bearing the organic substituent groups methyl, octyl, octadecyl, vinyl, phenyl, mercaptopropyl, isocyanatopropyl, chloropropyl and glycidoxypropyl were synthesized by an acid-catalyzed, hydrolytic sol-gel process. The resulting solid materials were characterized by their absorbance and attenuated total reflection (ATR) IR and Raman spectra. The latter technique proved to be particularly useful in the identification of the organic moieties in the hybrid silicas. The effect of the presence of the organic groups on the silica networks was also investigated - there were increases observed in both the SiOSi bond angles and bond lengths. Moreover, deconvolution of the IR-active antisymmetric SiOSi stretching bands permitted detection of the four- and six-membered siloxane rings present in the silicas. There proved to be a greater number of four-membered rings on the surfaces of the particles. Both IR and Raman spectroscopy proved to be invaluable in the characterization of these hybrid materials.

  13. Highly oriented, self-assembled alkanephosphate monolayers on tantalum(V) oxide surfaces

    SciTech Connect

    Brovelli, D.; Haehner, G.; Ruiz, L.

    1999-06-22

    Octadecyl phosphoric acid ester has been found to produce oriented, well-ordered monolayers on a flat tantalum(V) oxide surface, via self-assembly from a heptane/propan-2-ol solution. By means of contact angle, optical waveguide lightmode spectroscopy (OWLS), near-edge X-ray absorption fine structure spectroscopy (NEXASFS), and X-ray photoelectron spectroscopy (XPS) measurements, it has been shown that these layers closely resemble those formed by the corresponding thiol-gold system, with respect to packing density, inclination, and order. The system shows promise as an approach to functionalizing oxide surfaces with well-ordered organic monolayers, with potential applications in the fields of biochemical analysis and sensors.

  14. Synthesis, characterization and physicochemical properties of oleic acid ether derivatives as biolubricant basestocks.

    PubMed

    Salimon, Jumat; Salih, Nadia; Yousif, Emad

    2011-01-01

    Petroleum is a finite source as well as causing several environmental problems. Therefore petroleum needs to be replaced by alternative and sustainable sources. Plant oils and oleochemicals derived from them represent such alternative sources; the use of oleochemicals as biobased lubricants is of significant interest. This article presents a series of chemical modification on oleic acid to yield synthetic biolubricant basestocks. Measuring of density, volatility, cloud point (CP), pour point (PP), flash point (FP), viscosity index (VI), onset temperature (OT) and signal maximum temperature (SMT) was carried out for each compound. Furthermore, the friction and wear properties were measured using high-frequency reciprocating rig (HFRR). The results showed that octadecyl 9-octadecyloxy-10-hydroxyoctadecanoate exhibited the most favorable low-temperature performance (CP %ndash;26°C, PP %ndash;28°C) and the lowest ball wear scan diameter (42 µm) while propyl 9-propyloxy-10-hydroxyoctadecanoate exhibited the higher oxidation stability (OT 156°C).

  15. Antioxidative effect of lipophilized caffeic acid in fish oil enriched mayonnaise and milk.

    PubMed

    Alemán, Mercedes; Bou, Ricard; Guardiola, Francesc; Durand, Erwann; Villeneuve, Pierre; Jacobsen, Charlotte; Sørensen, Ann-Dorit Moltke

    2015-01-15

    The antioxidative effect of lipophilized caffeic acid was assessed in two different fish oil enriched food products: mayonnaise and milk. In both emulsion systems, caffeic acid esterified with fatty alcohols of different chain lengths (C1-C20) were better antioxidants than the original phenolic compound. The optimal chain length with respect to protection against oxidation was, however, different for the two food systems. Fish oil enriched mayonnaise with caffeates of medium alkyl chain length (butyl, octyl and dodecyl) added resulted in a better oxidative stability than caffeates with shorter (methyl) or longer (octadecyl) alkyl chains. Whereas in fish oil enriched milk emulsions the most effective caffeates were those with shorter alkyl chains (methyl and butyl) rather than the ones with medium and long chains (octyl, dodecyl, hexadecyl and eicosyl). These results demonstrate that there might be an optimum alkyl chain length for each phenolipid in each type of emulsion systems.

  16. Lipophilicity Assessment of Ruthenium(II)-Arene Complexes by the Means of Reversed-Phase Thin-Layer Chromatography and DFT Calculations

    PubMed Central

    Shweshein, Khalil Salem A. M.; Andrić, Filip; Radoičić, Aleksandra; Gruden-Pavlović, Maja; Tešić, Živoslav; Milojković-Opsenica, Dušanka

    2014-01-01

    The lipophilicity of ten ruthenium(II)-arene complexes was assessed by reversed-phase thin-layer chromatography (RP-TLC) on octadecyl silica stationary phase. The binary solvent systems composed of water and acetonitrile were used as mobile phase in order to determine chromatographic descriptors for lipophilicity estimation. Octanol-water partition coefficient, logKOW, of tested complexes was experimentally determined using twenty-eight standard solutes which were analyzed under the same chromatographic conditions as target substances. In addition, ab initio density functional theory (DFT) computational approach was employed to calculate logKOW values from the differences in Gibbs' free solvation energies of the solute transfer from n-octanol to water. A good overall agreement between DFT calculated and experimentally determined logKOW values was established (R2 = 0.8024–0.9658). PMID:24587761

  17. Preparation of 1,8-di-O-alkylaloe-emodins and 15-amino-, 15-thiocyano-, and 15-selenocyanochrysophanol derivatives from aloe-emodin and studying their cytotoxic effects.

    PubMed

    Cui, Xing-Ri; Takahashi, Kazutoshi; Shimamura, Takeshi; Koyanagi, Jyunichi; Komada, Fusao; Saito, Setsuo

    2008-04-01

    1,8-di-O-alkylaloe-emodin derivatives (namely, methyl-, propyl-, hexyl-, dodecyl-, and octadecyl) were synthesized from naturally occurring aloe-emodin. Further, derivatives having various substituents such as diethylamino, pyrrolidinyl, piperidinyl, methylpiperazinyl, imidazolyl, thiocyano and selenocyano groups at the 15 position of chrysophanol and 1,8-di-O-hexylchrysophanol from aloe-emodin were synthesized. The cytotoxic effects of these derivatives on less P-glycoprotein (P-gp)-expressing HCT 116 cells and stably P-gp-expressing Hep G2 cells were evaluated by performing 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Among these products, several of them exhibited markedly higher potent cytotoxic effects not only on HCT116 cells but also Hep G2 cancer cells as compared to aloe-emodin.

  18. Chemo-enzymatic synthesis of rac 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholine and its analogues.

    PubMed

    Vijeeta, Tadla; Balakrishna, Marrapu; Lakshmi Karuna, Mallampalli Sri; Surya Koppeswara Rao, Bhamidipati Venkata; Narayana Prasad, Rachapudi Badari

    2014-01-01

    The synthesis of rac 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholines (6a-c), blood platelet activating ether lipid analogues has been achieved in a four-step sequence from epichlorohydrin (1). Etherification of epichlorohydrin with different alcohols namely tetradecyl (2a), hexadecyl (2b) and octadecyl (2c) alcohols gave glycidyl ethers (3a-c) with 78-80% yields. The second step involved opening of the epoxide by acetic anhydride to give acetylated products (4a-c, 76-78% yield), which were subsequently hydrolyzed selectively, a key step of the method employing a 1,3 specific lipase to obtain rac 1-O-alkyl-2- acetylglycerol (5a-c) with 45-50% yields. The hydrolyzed products (5a-c) were phosphorylated to obtain rac 1-O-alkyl-2-acetyl-sn-glycero-3-phosphocholines (6a-c) in 80-85% yields.

  19. Using a new ligand for solid phase extraction of mercury.

    PubMed

    Soleimani, Majid; Mahmodi, Mohamad Saleh; Morsali, Ali; Khani, Azam; Afshar, Majid Ghahraman

    2011-05-15

    The octadecyl silica cartridge as a sorbent and 4-bp db (1,4-bis(4-pyridyl)-2,3-diaza-1,3-butadiene) as a ligand is a simple, rapid and reliable method for extracting and preconcentrating of Hg(II) in real samples prior to cold vapor atomic absorption spectrometry. Sample solutions were passed through a column at pH 4.5 then retained mercury ions on the column were eluted with minimal amount of 0.01 M nitric acid with 3 mL min(-1) flow rate. The effect of pH, type of buffer, flow rate of sample and eluent, type and volume of the eluent were investigated and optimized. At optimum effective parameters, concentration factor and detection limit were achieved 128 and 1.87 ng L(-1), respectively.

  20. Synthesis of paf-acether from exogenous precursors by the prokaryote Escherichia coli.

    PubMed

    Denizot, Y; Dassa, E; Kim, H Y; Bossant, M J; Salem, N; Thomas, Y; Benveniste, J

    1989-01-16

    Paf-acether (paf) is a potent mediator of inflammatory diseases and septic shock. Using normal-phase HPLC, a paf-like activity was found in culture supernatants from E. coli. Prokaryotic paf exhibited the same biological and physico-chemical properties as eukaryotic cells and synthetic paf. Further, reverse-phase HPLC indicates that paf generated by bacteria is predominantly of the hexadecyl and octadecyl species. When cultures were supplemented with lyso-paf, a dramatic increase in paf production was observed. The purity and molecular structure of bacterial paf were further characterized by mass spectral analysis. These results could be of importance considering the pathogenetic role of enterobacteria. Further, it appears that the competence to form and release paf is an early phylogenetic development.

  1. Determination of benzo(a)pyrene in the total particulate matter of cigarette smoke

    SciTech Connect

    Risner, C.H.

    1988-03-01

    A procedure for the isolation and determination of benzo(a)pyrene in the total particulate matter of cigarette smoke is described. Two high-pressure liquid chromatographic (HPLC) techniques are employed: a normal-phase, mu Bondapak-NH2, amino column is used for isolation of the benzo(a)pyrene fraction and a reversed-phase, Vydac 201TP54, polymeric octadecyl silane column is used for quantitation. Fluorescence detection is used in both modes of chromatography. The wavelengths of excitation and emission are evaluated for analytical detection. Extraction media and various isolation techniques are compared for their extraction efficiency and isolation from interferences, respectively. The procedure is efficient, reproducible, sensitive (3 pg), and gives results that compare favorably with other techniques reported in the literature for the B(a)P content of reference cigarettes, 1R1 and 1R4F.

  2. Determination of the 1'S and 1'R diastereomers of metolachlor and S-metolachlor in water by chiral liquid chromatography-mass spectrometry/mass spectrometry (LC/MS/MS).

    PubMed

    Kabler, A Kent; Chen, Sunmao

    2006-08-23

    An enantioselective method for the separation and quantification of the diastereomer pairs of metolachlor and S-metolachlor in surface and ground waters is presented. Samples are purified and concentrated using a C18 (octadecyl silica) solid-phase extraction (SPE) procedure and analyzed by chiral column liquid chromatography-mass spectrometry/mass spectrometry (LC/MS/MS) interfaced with either atmospheric pressure chemical ionization (APcI) or atmospheric pressure photoionization (APPI) sources. The overall mean percent procedural recoveries (percent relative standard deviations) are 89% (10.6%) for surface water and 80% (9.1%) for ground water. The method limit of quantitation (LOQ) is 0.10 ppb. The method validation was conducted under U.S. EPA FIFRA Good Laboratory Practice Guidelines 40 CFR 160.

  3. Quasi-homogeneous hydrogenation with platinum and palladium nanoparticles stabilized by dendritic core-multishell architectures.

    PubMed

    Schwarze, Michael; Keilitz, Juliane; Nowag, Sabrina; Parapat, Riny Y; Haag, Rainer; Schomäcker, Reinhard

    2011-05-17

    Platinum and palladium nanoparticles, supported and stabilized by polymeric core-shell architectures, proved to be active catalysts for hydrogenation reactions. Here, two different reactions were used as probes to investigate the influence of the polymeric support: the hydrogenation of α-methyl styrene (AMS) to cumene and the partial hydrogenation of 1,5-cyclooctadiene (COD). We found that the stability of the nanoparticles and the rate of reaction are higher in the presence of a hydrophobic octadecyl shell within a three-shell polymer system. The kinetic study of AMS hydrogenation showed much higher activities for palladium nanoparticles than for platinum nanoparticles, and the obtained results (e.g., 35 kJ/mol for the activation energy) are of the same order of magnitude as reported earlier for palladium supported on alumina. A methanol/n-heptane biphasic mixture was tested for catalyst recycling and allowed for highly efficient catalyst separation with very low metal leaching.

  4. Comparison of the performance of different silica hydride particles for the solid-phase extraction of non-volatile analytes from dark chocolate with analysis by gas chromatography-quadrupole mass spectrometry.

    PubMed

    Nolvachai, Yada; Kulsing, Chadin; Boysen, Reinhard I; Matyska, Maria T; Pesek, Joseph J; Marriott, Philip J; Hearn, Milton T W

    2015-05-01

    The extraction capabilities of a Diamond Hydride™ phase, as well as silica hydride phases modified with bidentate octadecyl (BDC(18)), phenyl or cholesteryl groups, were evaluated for the analysis of fatty acids, amino acids, sugars and sterols in a dark chocolate extract. These batch adsorption performances were investigated using either methanol or aqueous methanol as the solvent. The compositions of the extracted fractions were assessed by gas chromatography interfaced with quadrupole mass spectrometry (GC-qMS). The batch binding propensities of the various compound classes with silica hydride particles modified with immobilised phenyl groups or larger ligands followed trends predicted from linear solvation energy relationships. Both prediction and experiment revealed that better extraction results could be obtained with the phenyl, BDC(18) and cholesteryl hydride particles for the major chocolate components. Based on these results, separations in micro-pipette tip format with these three types of stationary phase particles have been undertaken.

  5. Studies on Mixed Monolayers and Langmuir-Blodgett Films of Schiff-Base Complex Cu(SBC(18))(2) and Calix

    PubMed

    Pang, Shufeng; Ye, Zhifeng; Li, Chun; Liang, Yingqiu

    2001-08-15

    Mixed monolayers of Schiff-base complex Cu(SBC(18))(2) with an octadecyl hydrocarbon chain and Calix[4]arene without a long alkyl chain at an air/water interface were studied in ultrapure water at different temperatures. Interface behavior and thermodynamic estimation of the mixed monolayer indicate that a strong intermolecular interaction exists between the mixed components (Cu(SBC(18))(2) and calix[4]arene) and the two-dimensional miscibility decreases with the molar fraction of Cu(SBC(18))(2). It is noticeable that the calix[4]arene monolayer can be transferred successfully onto solid substrates due to the introduction of Cu(SBC(18))(2). FTIR transmission and UV-Vis absorption spectra of mixed LB films provide further evidence of molecular interaction between the headgroups. Copyright 2001 Academic Press.

  6. Detection of O6-monoacetylmorphine in urine samples by GC/MS as evidence for heroin use.

    PubMed

    Fehn, J; Megges, G

    1985-01-01

    A method for qualitative and quantitative detection of nanogram amounts of O6-monoacetylmorphine (MAM) in urine samples of heroin abusers is presented. The detection of MAM is based on the alkaline solid phase extraction of the urine samples using an octadecyl column and transformation into the pentafluoropropionyl (PFP) derivatives. PFP-MAM is separated by capillary GC and identified mass spectrometrically by selected ion monitoring (SIM). The determination of the MAM levels was carried out by quantitative GC/SIM using nalorphine as the internal standard. A positive identification of MAM allows one to distinguish between a previous intake of heroin (or theoretically MAM) on the one hand, and an ingestion of morphine, codeine, opium, or poppy seed on the other.

  7. Self-assembly of cellulose nanoparticles as electrolyte additive for capillary electrophoresis separation.

    PubMed

    Huang, Dihui; Yang, Qin; Jin, Shanxia; Deng, Qianchun; Zhou, Ping

    2014-11-07

    In this work, a new cellulose derivative, octadecyl modified quaternized cellulose (ODMQC), was synthesized and used as additive in the background electrolyte for capillary electrophoresis. The derivative bearing hydrophobic groups and hydrophilic groups can self-assemble into a stable nano-scaled micelle structure in aqueous solution. When ODMQC was added in running buffer, the capillaries were shown to generate applicable anodal EOF over the investigated range of pH 3.0-12.0. Due to the lack of UV active groups, the ODMQC did not disturb the UV detection. It is shown that ODMQC-added capillaries allow the separation of basic proteins by reducing their adsorption onto the capillary wall. Also, the addition of ODMQC provides adequate separation of aromatic acids with low pKa values and improved separation of sulfa drugs. Moreover, it is demonstrated that the addition of ODMQC can incorporate an additional reversed-phase mechanism that improves the separation of neutral analytes.

  8. van der Waals force-induced loading of proangiogenic nanoparticles on microbubbles for enhanced neovascularization

    NASA Astrophysics Data System (ADS)

    Chen, Jinrong; Lee, Min Kyung; Qin, Ellen; Misra, Sanjay; Kong, Hyunjoon

    2015-10-01

    Nanoparticles emerged as carriers of promising diagnostic and therapeutic molecules due to their unique size, injectability, and potential to sustainably release molecular cargos. However, with local injection of particles into target tissue, the significant particle loss caused by external biomechanical forces is a great challenge yet to be resolved to date. We hypothesized that nanoparticles associated with tissue-adherent microbubbles in the form of core-shell particles due to van der Waals attractive forces would stably remain on an implanted site and significantly increase therapeutic efficacy of drug cargos. To examine this hypothesis, we used 100 nm diameter nanoparticles made of poly(lactide-co-glycolic acid) (PLGA) as a model nanoparticle and 50 μm diameter microbubbles made of poly(2-hydroxyethyl aspartamide) (PHEA) grafted with octadecyl chains, PHEA-g-C18, as a model microbubble. Simple mixing of PLGA nanoparticles and PHEA-g-C18 microbubbles resulted in the core-shell particles. Following implantation, the PHEA-g-C18 microbubbles acted as glue to minimize the displacement of PLGA nanoparticles, because of the association between the octadecyl chains on PHEA-g-C18 and the epithelium of the tissue. As a consequence, the core-shell particles prepared with Angiopoietin-1 (Ang1)-encapsulated PLGA nanoparticles significantly promoted vascularization in the implanted tissue. Overall, the results of this study provide a simple but advanced strategy for improving therapeutic efficacy of drug-carrying nanoparticles without altering their surface chemistry and potential.Nanoparticles emerged as carriers of promising diagnostic and therapeutic molecules due to their unique size, injectability, and potential to sustainably release molecular cargos. However, with local injection of particles into target tissue, the significant particle loss caused by external biomechanical forces is a great challenge yet to be resolved to date. We hypothesized that nanoparticles

  9. Development and application of a new 25,27-bis(L-phenylalaninemethylester-N-carbonylmethoxy)-26,28-dihydroxy-para-tert-butylcalix[4]arene stationary phase.

    PubMed

    Hu, Kai; Zhang, Yanhao; Liu, Junwei; Chen, Kangkang; Zhao, Wenjie; Zhu, Weixia; Song, Zhichao; Ye, Baoxian; Zhang, Shusheng

    2013-02-01

    A 25,27-bis(L-phenylalaninemethylester-N-carbonylmethoxy)-26,28-dihydroxy- para-tert-butylcalix[4]arene-bonded silica gel stationary phase was synthesized, structurally characterized and used for LC. Its separation mechanism was studied and compared with octadecyl-bonded stationary phase, as well as our previously prepared para-tert-butylcalix[4]arene-1,2-crown-4 stationary phase. Meanwhile, the chromatographic behaviors were investigated by using polycyclic aromatic hydrocarbons, monosubstituted benzenes, anilines, phenols, Tanaka tests solutes, fluoroquinolones, and flavonoids as probes. Mechanisms involved in the chromatographic separation included hydrophobic, π-π and π-electron transfer, hydrogen bonding, and inclusion interactions. Moreover, the column was successfully employed for the analysis of the illegal additive of melamine in milk product.

  10. Degradation of thiram in water, soil and plants: a study by high-performance liquid chromatography.

    PubMed

    Gupta, Bina; Rani, Manviri; Kumar, Rahul

    2012-01-01

    A comprehensive study was conducted to evaluate the persistence of thiram in water and soil under controlled conditions and on two plants, namely tomato and radish, in field conditions. In order to follow the decay of the pesticide, an HPLC procedure was developed employing an octadecyl endcapped RP-C18 column using a mixture of acetonitrile and water as the mobile phase and an ultraviolet detector. Studies conducted in water at different temperature, pH and organic content revealed that the persistence of the pesticide decreases with the increase in all the three variables. In the three different types of soils studied, the effect of pH was more or less apparent on a similar line. On average a slower decay was observed in the case of plants than in water and soil.

  11. Two-dimensional liquid chromatography (LC) of phenolic compounds from the shoots of Rubus idaeus 'Glen Ample' cultivar variety.

    PubMed

    Kula, Marta; Głód, Daniel; Krauze-Baranowska, Mirosława

    2016-03-20

    In this study the application of two-dimensional LC (2D LC) for qualitative analysis of polyphenols and simple phenols in the shoots of Rubus idaeus 'Glen Ample' variety is presented. In the preliminary analysis, the methanol extract of the shoots was analyzed by one-dimensional LC. One-dimensional LC separation profiles of phenolics from R. idaeus 'Glen Ample' shoots were dependent on column type, mobile phase composition and gradient program used. Two-dimensional LC system was built from connecting an octadecyl C-18 silica column in the first dimension and pentafluorophenyl column in the second dimension, coupled with DAD and MS (ESI, APCI, DUIS ionization) detectors. A total of 34 phenolic compounds belonging to the groups of phenolic acids, ellagitannins, flavan-3-ols, flavonols and ellagic acid conjugates were identified in the shoots of R. idaeus 'Glen Ample'. The established 2D LC method offers an effective tool for analysis of phenolics present in Rubus species.

  12. Liquid chromatography-tandem mass spectrometric assay for clobetasol propionate in human serum from patients with atopic dermatitis.

    PubMed

    Sparidans, Rolf W; van Velsen, Sara G A; de Roos, Marlise P; Schellens, Jan H M; Bruijnzeel-Koomen, Carla A F M; Beijnen, Jos H

    2010-08-01

    A bioanalytical assay for the topical corticosteroid clobetasol propionate was developed and validated. For the quantitative assay 0.5 ml human serum samples, supplemented with clobetasone butyrate as internal standard, were extracted with hexane-ether. Evaporated and reconstituted extracts were injected on a polar embedded octadecyl silica column with isocratic elution using formic acid in water-methanol as mobile phase. The eluate was led into the electrospray interface with positive ionization and the analyte was detected and quantified using the selective reaction monitoring mode of a triple quadrupole mass spectrometer. The assay was validated in the range 0.04-10 ng/ml, the lowest level of this range being the lower limit of quantification. Precisions were 5-10% and accuracies were between 102 and 109%. The drug was stable under all relevant conditions. Finally, the assay was successfully applied on patients suffering from severe atopic dermatitis treated topically with clobetasol propionate.

  13. Extraction of amphetamines and methylenedioxyamphetamines from urine using a monolithic silica disk-packed spin column and high-performance liquid chromatography-diode array detection.

    PubMed

    Namera, Akira; Nakamoto, Akihiro; Nishida, Manami; Saito, Takeshi; Kishiyama, Izumi; Miyazaki, Shota; Yahata, Midori; Yashiki, Mikio; Nagao, Masataka

    2008-10-24

    To overcome the limitations of solid-phase extraction, we developed a device comprising a spin column packed with octadecyl silane-bonded monolithic silica for extracting amphetamines and methylenedioxyamphetamines from urine. Urine (0.5mL), buffer (0.4mL), and methoxyphenamine (internal standard) were directly put into the preactivated column. The column was centrifuged (3000rpm, 5min) for sample loading and washed. The adsorbed analytes were eluted and analyzed by high-performance liquid chromatography, without evaporation. The results were as follows: linear curves (drug concentrations of 0.2-20microg/mL); correlation coefficients >0.99; detection limit, 0.1microg/mL. The proposed method is not only useful for drugs from biological materials but also highly reproducible for the analysis of these drugs in urine.

  14. Simultaneous enantioselective quantification of fluoxetine and norfluoxetine in human milk by direct sample injection using 2-dimensional liquid chromatography-tandem mass spectrometry.

    PubMed

    Alvim-Jr, Joel; Lopes, Bianca Rebelo; Cass, Quezia Bezerra

    2016-06-17

    A two-dimensional liquid chromatography system coupled to triple quadrupole tandem mass spectrometer (2D LC-MS/MS) was employed for the simultaneously quantification of fluoxetine (FLX) and norfluoxetine (NFLX) enantiomers in human milk by direct injection of samples. A restricted access media of bovine serum albumin octadecyl column (RAM-BSAC18) was used in the first dimension for the milk proteins depletion, while an antibiotic-based chiral column was used in the second dimension. The results herein described show good selectivity, extraction efficiency, accuracy, and precision with limits of quantification in the order of 7.5ngmL(-1)for the FLX enantiomers and 10.0ngmL(-1) for NFLX enantiomers. Furthermore, it represents a practical tool in terms of sustainability for the sample preparation of such a difficult matrix.

  15. Can matrix solid phase dispersion (MSPD) be more simplified? Application of solventless MSPD sample preparation method for GC-MS and GC-FID analysis of plant essential oil components.

    PubMed

    Wianowska, Dorota; Dawidowicz, Andrzej L

    2016-05-01

    This paper proposes and shows the analytical capabilities of a new variant of matrix solid phase dispersion (MSPD) with the solventless blending step in the chromatographic analysis of plant volatiles. The obtained results prove that the use of a solvent is redundant as the sorption ability of the octadecyl brush is sufficient for quantitative retention of volatiles from 9 plants differing in their essential oil composition. The extraction efficiency of the proposed simplified MSPD method is equivalent to the efficiency of the commonly applied variant of MSPD with the organic dispersing liquid and pressurized liquid extraction, which is a much more complex, technically advanced and highly efficient technique of plant extraction. The equivalency of these methods is confirmed by the variance analysis. The proposed solventless MSPD method is precise, accurate, and reproducible. The recovery of essential oil components estimated by the MSPD method exceeds 98%, which is satisfactory for analytical purposes.

  16. Antioxidant and antiatherogenic activity of cis-Hinokiresinol from Trapa pseudoincisa.

    PubMed

    Song, Myoung-Chong; Yang, Hye-Joung; Bang, Myun-Ho; Kim, Dae-Keun; Jeong, Tae-Sook; Kim, Jong-Pyung; Baek, Nam-In

    2007-11-01

    cis-Hinokiresinol, also known as (+)-nyasol, was isolated for the first time from an aquatic herbaceous plant, Trapa pseudoincisa NAKAI, via silica gel and octadecyl silica gel column chromatographies. The chemical structure was determined via analyses of the spectroscopic data, including NMR, MS and IR. cis-Hinokiresinol was also found to exhibit antioxidant and antiatherogenic activities. The ICso values for the scavenging activities of cis-hinokiresinol on ABTS cation and superoxide anion radicals were 45.6 and 40.5 microM, respectively. The IC50 values for the inhibitory effects on Lp-PLA2, hACAT1, hACAT2 and LDL-oxidation were 284.7, 280.6, 398.9 and 5.6 microM, respectively.

  17. Determination of selected azaarenes in water by bonded-phase extraction and liquid chromatography

    USGS Publications Warehouse

    Steinheimer, T.R.; Ondrus, M.G.

    1986-01-01

    A method for the rapid and simple quantitative determination of quinoline, isoquinoline, and five selected three-ring azaarenes in water has been developed. The azaarene fraction is separated from its carbon analogues on n-octadecyl packing material by edition with acidified water/acetonitrile. Concentration as great as 1000-fold is achieved readily. Instrumental analysis involves high-speed liquid chromatography on flexible-walled, wide-bore columns with fluorescence and ultraviolet detection at several wavelengths employing filter photometers in series. Method-validation data is provided as azaarene recovery efficiency from fortified samples. Distilled water, river water, contaminated ground water, and secondary-treatment effluent have been tested. Recoveries at part-per-billion levels are nearly quantitative for the three-ring compounds, but they decrease for quinoline and isoquinoline. ?? 1986 American Chemical Society.

  18. Lipophilicity assessment of ruthenium(II)-arene complexes by the means of reversed-phase thin-layer chromatography and DFT calculations.

    PubMed

    Shweshein, Khalil Salem A M; Andrić, Filip; Radoičić, Aleksandra; Zlatar, Matija; Gruden-Pavlović, Maja; Tešić, Zivoslav; Milojković-Opsenica, Dušanka

    2014-01-01

    The lipophilicity of ten ruthenium(II)-arene complexes was assessed by reversed-phase thin-layer chromatography (RP-TLC) on octadecyl silica stationary phase. The binary solvent systems composed of water and acetonitrile were used as mobile phase in order to determine chromatographic descriptors for lipophilicity estimation. Octanol-water partition coefficient, logK(OW), of tested complexes was experimentally determined using twenty-eight standard solutes which were analyzed under the same chromatographic conditions as target substances. In addition, ab initio density functional theory (DFT) computational approach was employed to calculate logK(OW) values from the differences in Gibbs' free solvation energies of the solute transfer from n-octanol to water. A good overall agreement between DFT calculated and experimentally determined logK(OW) values was established (R(2) = 0.8024-0.9658).

  19. Composition and method for encapsulating photovoltaic devices

    DOEpatents

    Pern, Fu-Jann

    2000-01-01

    A composition and method for encapsulating a photovoltaic device which minimizes discoloration of the encapsulant. The composition includes an ethylene-vinyl acetate encapsulant, a curing agent, an optional ultraviolet light stabilizer, and/or an optional antioxidant. The curing agent is preferably 1,1-di-(t-butylperoxy)-3,3,5-trimethylcyclohexane; the ultraviolet light stabilizer is bis-(N-octyloxy-tetramethyl) piperidinyl sebacate and the antioxidant is selected from the group consisting of tris (2,4-di-tert-butylphenyl) phosphite, tetrakis methylene (3,5-di-tert-butyl-4-hydroxyhydrocinnamate) methane, octadecyl 3,5-di-tert-butyl-4-hydroxyhydrocinnamate, and 2,2'-ethylidene bis(4,6-di-t-butylphenyl) fluorophosponite. The composition is applied to a solar cell then cured. The cured product contains a minimal concentration of curing-generated chromophores and resists UV-induced degradation.

  20. Synthesis and antitumor activity of new amphiphilic alkylglycerolipids substituted with a polar head group, 2-(2-trimethylammonioethoxy)ethyl or a congeneric oligo(ethyleneoxy)ethyl group.

    PubMed

    Ukawa, K; Imamiya, E; Yamamoto, H; Aono, T; Kozai, Y; Okutani, T; Nomura, H; Honma, Y; Hozumi, M; Kudo, I

    1989-12-01

    A new series of amphiphilic 1-octadecyl glycerolipids (eleven compounds, 1a-k) were designed and synthesized, in which the 3-phosphocholine portion of platelet-activating factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) was replaced by the 2-(2-trimethylammonioethoxy)ethyl group and congeneric groups having oligo(ethyleneoxy)ethyl bridges of various lengths at position 3, together with modification at position 2 (lower alkyl, acetonyl, acetoacetyl, carboxymethyl and pyrimidin-2-yl groups). These ether lipids, characterized by a nonphosphorus lysoglycerolipid structure, showed potent antitumor activity in vitro (human promyelocytic leukemia cells, HL-60, and human epidermoid carcinoma cells, KB) and in vivo (mouse sarcoma S180 and mouse mammary carcinoma MM46). Maximal in vitro potency was obtained with 1-O-octadecyl-2-O-(2-pyrimidinyl)-3-O-[2-(2-trimethylammonioethoxy )ethyl] glycerol (1g; IC50 values for both HL-60 and KB were 0.32 microgram/ml, indicating a higher activity than alkyl-lysophospholipid, ET18-OMe). Several appropriately 2-substituted 1-octadecylglycerolipids with the 3-[2-(2-trimethylammonioethoxy)ethyl] group (e.g., methyl, 1b; butyl, 1f; 2,2,2-trifluoroethyl, 1j; and acetonyl, 1k) showed a potent life-span-prolonging effect on mice with ascites sarcoma S180 and on those with mammary carcinoma MM46, when administered intraperitoneally at 16.5 and 12.5 mg/kg/d, respectively. Compounds 1b and 1k showed definite tumor growth inhibition against solid sarcoma S180 in mice, whether given p.o. or i.v. at 16.5 mg/kg/d. Studies on the structure-activity relationships indicate that the metabolic stability to phospholipase C or related enzymes is at least partly responsible for the potent antitumor activity of this series of ether lipids.

  1. Determination of selectivity differences for basic compounds in gradient reverse phase high performance liquid chromatography under high pH conditions by partial least squares modelling.

    PubMed

    Fornal, Emilia; Borman, Phil; Luscombe, Christopher

    2006-06-16

    The retention behaviour of compounds in a chromatographic system is believed to be multivariate by nature, i.e. many physico-chemical properties of an analyte can influence its retention. Principal component analysis (PCA) and partial least squares (PLS) can therefore be particularly useful tools for visualising, exploring and modelling the complex interactions between solutes and the mobile and stationary phase. PCA allows the relationships between compounds (the observations) and their retention parameters (the variables) to be visualised in usually just two or three dimensions. PLS can be used to model quantitative structure-retention relationships (QSRRs) and may lead to better understanding of retention and selectivity changes in chromatographic systems. The objective of the study was to investigate the chromatographic behaviour of basic compounds under optimised gradient conditions using octadecyl high performance liquid chromatography (HPLC) columns designed for high pH separations. Three pharmaceutical mixtures were analysed by linear gradient reverse phase HPLC (RP-HPLC) at high pH using ammonia as a pH modifier, and methanol and/or acetonitrile as the organic modifier. The separations were carried out on three octadecyl columns: Waters XTerra MS C18, Agilent Zorbax Extend C18 and Thermo Hypersil-Keystone BetaBasic-18. Multivariate PCA and PLS modelling were employed to explore and explain the differences in selectivity between the chromatographic systems studied when the basic compounds were analysed under the high pH conditions. The interactions between the analytes and the mobile-stationary phases were described by relating the compound molecular descriptors with the selectivity of each chromatographic system. The selectivity differences between the chromatographic systems were identified.

  2. Reversed-phase liquid chromatographic retention and membrane activity relationships of local anesthetics.

    PubMed

    Tsuchiya, Hironori; Mizogami, Maki; Takakura, Ko

    2005-05-06

    The chromatographic retention and membrane activity relationships of local anesthetics were studied to address the possible mechanisms for structure specificity and inflammation-associated decrease of their effects. Five representative drugs (3 mM for each) were reacted with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine liposomes in 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA) for 10 min at 37 degrees C and the membrane fluidity changes were analyzed by measuring fluorescence polarization with 1,6-diphenyl-1,3,5-hexatriene. Their capacity factors were determined on octadecyl-, octyl- and phenyl-bonded silica columns with a mobile phase consisting of 25 mM potassium phosphate buffer (pH 5.9-7.9, containing 100 mM NaCl and 0.1 mM EDTA)-methanol (30:70, v/v) at a flow rate of 1.0 ml/min and at a column temperature of 37 degrees C and diode-array detection. Mepivacaine, prilocaine, lidocaine, ropivacaine and bupivacaine fluidized membranes in increasing order of intensity, which agreed with their clinical potency. The relative degree of membrane fluidization correlated with that of retention on an octadecyl stationary phase more significantly than the other phases. Both membrane-fluidizing effects and capacity factors decreased by lowering the reaction and mobile phase pH, being consistent with the hypothesis that anesthetic potency is reduced in inflammation because of tissue acidity. Reversed-phase liquid chromatography appears to be useful for estimating the structure-specific and pH-dependent membrane-fluidizing effects of local anesthetics.

  3. Rivastigmine-loaded in situ gelling nanostructured lipid carriers for nose to brain delivery.

    PubMed

    Wavikar, Preeti R; Vavia, Pradeep R

    2015-01-01

    In the current research work, rivastigmine (RV)-loaded in situ gelling nanostructured lipid carriers (NLCs) were developed for nose to brain delivery. NLCs were fabricated by ethanol injection method using glyceryl monosterate, Capmul MCM C8, Lecithin and Tween 80. NLCs showed average particle size of 123.2 ± 2.3 nm with entrapment efficiency of 68.34 ± 3.4%. DSC, XRD and IR studies showed complete amorphization and incorporation of the drug into nanoparticles. NLCs were incorporated into an in situ gelling system using 0.8% gellan gum and 15% Lutrol F 127. RV in situ gel showed excellent elasticity, rheology, mucoadhesion and adhesiveness to facilitate its adhesion to the upper nasal mucosa. NLC-based in situ gel showed a 2-fold increase in nasal permeation of the drug over plain RV solution. In situ gelling NLCs showed a 3-fold increase in enzyme inhibition efficacy.

  4. Biological denitration of propylene glycol dinitrate by Bacillus sp. ATCC 51912.

    PubMed

    Sun, W Q; Meng, M; Kumar, G; Geelhaar, L A; Payne, G F; Speedie, M K; Stacy, J R

    1996-05-01

    In previous studies, bacterial cultures were isolated that had the ability to degrade the nitrate ester glyceryl trinitrate (i.e., nitroglycerin). The goal of the present study was to examine the ability of resting cells and cell-free extracts of the isolate Bacillus sp. ATCC 51912 to degrade the more recalcitrant nitrate ester propylene glycol dinitrate (PGDN). It was observed that the PGDN-denitrating activity was expressed during growth even when cells were cultured in the absence of nitrate esters. This indicates that nitrate esters are not required for expression of denitration activity. Using cell-free extracts, PGDN was observed to be sequentially denitrated to propylene glycol mononitrate (PGMN) and propylene glycol with the second denitration step proceeding more slowly than the first. Also it was observed that dialysis of the cell-free extracts did not affect denitration activity indicating that regenerable cofactors [e.g., NAD(P)H or ATP] are not required for denitration.

  5. Nitric oxide signaling pathway activation inhibits the immune escape of pancreatic carcinoma cells

    PubMed Central

    LU, YEBIN; HU, JUANJUAN; SUN, WEIJIA; DUAN, XIAOHUI; CHEN, XIONG

    2014-01-01

    The aim of the present study was to investigate the effect of the nitric oxide signaling pathway on immune escape; thus, a tumorigenesis model was established using nude mice. The mice were inoculated with pancreatic carcinoma cells and divided into two groups, a glyceryl trinitrate (GTN) and a placebo group. When tumor volumes reached 150 mm3, the mice in the GTN group were treated with GTN transdermal patches (dose, 7.3 μg/h) while the mice in the placebo group were administered untreated patches. Following treatment, the tumor volume was recorded every 3–4 days and after 28 days, the tumors were analyzed. The results indicated that GTN treatment may reduce the levels of soluble major histocompatibility complex class I chain-related molecules, and natural killer group 2 member D, as well as inhibiting tumor growth. PMID:25364398

  6. Biosynthesis of murein lipoprotein in Escherichia coli: effects of 3,4-dihydroxybutyl-1-phosphonate.

    PubMed Central

    Chattopadhyay, P K; Engel, R; Tropp, B E; Wu, H C

    1979-01-01

    The effects of 3,4-dihydroxybutyl-1-phosphonate, a four-carbon analog of sn-glycerol 3-phosphate, on the biosynthesis of the glyceryl moiety in murein lipoprotein of Escherichia coli were studied. The compound at a concentration of 55 microM strong inhibits in the incorporation of [2-3H]glycerol radioactivity into lipoprotein by virtue of its inhibition of the synthesis of phosphatidylglycerol. On the other hand, the incorporation of prelabeled [2-3H]glycerol radioactivity into lipoprotein was only partially inhbited by 3,4-dihydroxybutyl-1-phosphonate even at a much higher concentration (1 mM). These data were consistent with the postulated pathway for the biosynthesis of the lipid moiety in lipoportein: cysteine-lipoprotein + phosphatidylglycerol leads to glycerylcystein-lipoprotein + phosphatidic acid. PMID:378946

  7. Guaifenesin in rhinitis.

    PubMed

    Storms, William; Farrar, Judith R

    2009-03-01

    Mucus in the airways is a complex mixture of water, lipids, glycoproteins, sugars, and electrolytes that serves as a lubricant for the epithelium. The efficient flow of respiratory mucus is a first level of immune defense that requires an appropriate viscosity and elasticity for optimal barrier and ciliary functions. Thickening and drying of airway mucus by respiratory tract infections, allergies, and drugs can impair evacuation. Tenacious, bothersome mucus is an annoying and frequent symptom of rhinitis that is difficult to manage. Common remedies include adequate hydration through fluid intake and nasal washes. The use of mucoactive agents is controversial due to limited data and equivocal efficacy in available studies. Nonetheless, some patients benefit. This review examines the use of guaifenesin (glyceryl guaiacolate) on bothersome nasal mucus associated with rhinitis, including the available published data and clinical experience.

  8. Emulsification at the Liquid/Liquid Interface: Effects of Potential, Electrolytes and Surfactants.

    PubMed

    Chowdhury, Mehrin; Kataky, Ritu

    2016-01-04

    Emulsification of oils at liquid/liquid interfaces is of fundamental importance across a range of applications, including detergency. Adsorption and partitioning of the anionic surface active ions at the interface between two immiscible solutions is known to cause predictable chaos at the transfer potential region of the surfactant. In this work, the phenomenon that leads to the chaotic behaviour shown by sodium dodecylbenzene sulfonate (SDBS) at the water/1,2-dichloroethane interface is applied to commercial surfactants and aqueous/glyceryl trioleate interface. Electrochemical methods, electrocapillary curves, optical microscopy and conductivity measurements demonstrated that at 1.5 mm of SDBS, surfactants are adsorbed at the interface and assemble into micelles, leading to interfacial instability. As the concentration of the anionic surfactant was enhanced to 8 and 13.4 mm, the Marangoni effect and the interfacial emulsification became more prominent. The chaotic behaviour was found to be dependent on the surfactant concentration and the electrolytes present.

  9. Effects of double-layer polarization on ion transport.

    PubMed Central

    Hainsworth, A H; Hladky, S B

    1987-01-01

    It has been proposed that changes in ionic strength will alter the shape of current-voltage relations for ion transport across a lipid membrane. To investigate this effect, we measured currents across glyceryl monooleate membranes at applied potentials between 10 and 300 mV using either gramicidin and 1 mM NaCl or valinomycin and 1 mM KCl. A bridge circuit with an integrator as null detector was used to separate the capacitative and ionic components of the current. The changes in the current-voltage relations when ionic strength is varied between 1 and 100 mM are compared with predictions of Gouy-Chapman theory for the effects of these variations on polarization of the electrical diffuse double-layer. Double-layer polarization accounts adequately for the changes observed using membranes made permeable by either gramicidin or valinomycin. PMID:2432953

  10. Mycobacteriocins produced by rapidly growing mycobacteria are Tween-hydrolyzing esterases.

    PubMed Central

    Saito, H; Tomioka, H; Watanabe, T; Yoneyama, T

    1983-01-01

    Smegmatocin, a protein produced by Mycobacterium smegmatis ATCC 14468, was found to have an esterase activity, hydrolyzing Tween 80, polyoxyethylene sorbitan monooleate, added to the assay medium for various "bacteriocins" from mycobacteria. Because M. diernhoferi ATCC 19340 (indicator strain for smegmatocin) is highly susceptible to oleic acid and smegmatocin requires Tween 80 for manifestation of its anti-M. diernhoferi activity, it is likely that smegmatocin-mediated antimicrobial action is caused by oleic acid generated by hydrolysis of Tween 80 by the inherent esterase action of smegmatocin. Other mycobacteriocins from rapidly growing mycobacteria also have inherent esterase activity against Tween 80 and require Tween 80 for expression of antimycobacterial action. Smegmatocin was found to hydrolyze various polyoxyethylene (sorbitan) fatty acyl esters but not sorbitan monooleate and glyceryl esters. Images PMID:6826523

  11. Effects of double-layer polarization on ion transport.

    PubMed

    Hainsworth, A H; Hladky, S B

    1987-01-01

    It has been proposed that changes in ionic strength will alter the shape of current-voltage relations for ion transport across a lipid membrane. To investigate this effect, we measured currents across glyceryl monooleate membranes at applied potentials between 10 and 300 mV using either gramicidin and 1 mM NaCl or valinomycin and 1 mM KCl. A bridge circuit with an integrator as null detector was used to separate the capacitative and ionic components of the current. The changes in the current-voltage relations when ionic strength is varied between 1 and 100 mM are compared with predictions of Gouy-Chapman theory for the effects of these variations on polarization of the electrical diffuse double-layer. Double-layer polarization accounts adequately for the changes observed using membranes made permeable by either gramicidin or valinomycin.

  12. High-Throughput Quantification of Bioactive Lipids by MALDI Mass Spectrometry: Application to Prostaglandins

    PubMed Central

    Manna, Joseph D.; Reyzer, Michelle L.; Latham, Joey C.; Weaver, C. David; Marnett, Lawrence J.; Caprioli, Richard M.

    2011-01-01

    Analysis and quantification of analytes in biological systems is a critical component of metabolomic investigations of cell function. The most widely used methods employ chromatographic separation followed by mass spectrometric analysis, which requires significant time for sample preparation and sequential chromatography. We introduce a novel high-throughput, separation-free methodology based on MALDI mass spectrometry that allows for the parallel analysis of targeted metabolomes. Proof-of-concept is demonstrated by analysis of prostaglandins and glyceryl prostaglandins. Derivatization to incorporate a charged moiety into ketone-containing prostaglandins dramatically increases the signal-to-noise ratio relative to underivatized samples. This resulted in an increased dynamic range (15 fmol – 2000 fmol on plate) and improved linearity (r2= 0.99). The method was adapted for high-throughput screening methods for enzymology and drug discovery. Application to cellular metabolomics was also demonstrated. PMID:21770391

  13. Effect of sterilization on the physical stability of brimonidine-loaded solid lipid nanoparticles and nanostructured lipid carriers.

    PubMed

    El-Salamouni, Noha S; Farid, Ragwa M; El-Kamel, Amal H; El-Gamal, Safaa S

    2015-12-30

    Nanoparticulate delivery systems have recently been under consideration for topical ophthalmic drug delivery. Brimonidine base-loaded solid lipid nanoparticles and nanostructured lipid carrier formulations were prepared using glyceryl monostearate as solid lipid and were evaluated for their physical stability following sterilization by autoclaving at 121°C for 15min. The objective of this work was to evaluate the effect of autoclaving on the physical appearance, particle size, polydispersity index, zeta potential, entrapment efficiency and particle morphology of the prepared formulations, compared to non-autoclaved ones. Results showed that, autoclaving at 121°C for 15min allowed the production of physically stable formulations in nanometric range, below 500nm suitable for ophthalmic application. Moreover, the autoclaved samples appeared to be superior to non-autoclaved ones, due to their increased zeta potential values, indicating a better physical stability. As well as, increased amount of brimonidine base entrapped in the tested formulations.

  14. Assessment of Gasoline Additive Containing Ditert-butoxypropanol

    SciTech Connect

    West, Brian H.; Connatser, Raynella M.; Lewis, Samuel Arthur

    2016-04-01

    The Fuels, Engines, and Emissions Research Center completed analysis and testing of the CPS Powershot gasoline additive under the auspices of the Department of Energy’s Technical Assistance for US Small Businesses in Vehicle Technologies. Gas chromatography-mass spectrometry (GC-MS) was used to quantify the makeup of the additive, finding a predominance of 2,3-Ditert-Butoxypropanol, also known as Glyceryl Di-Tert-Butyl Ether (GTBE). Blends of the additive at 2 and 4 volume percent were subjected to a number of standard ASTM tests, including Research Octane Number, Motor Octane Number, distillation, and vapor pressure. Results show a high boiling range and low vapor pressure for the additive, and a very modest octane boosting effect in gasoline with and without ethanol.

  15. Comprehension of direct extraction of hydrophilic antioxidants using vegetable oils by polar paradox theory and small angle X-ray scattering analysis.

    PubMed

    Li, Ying; Fabiano-Tixier, Anne Sylvie; Ruiz, Karine; Rossignol Castera, Anne; Bauduin, Pierre; Diat, Olivier; Chemat, Farid

    2015-04-15

    Since the polar paradox theory rationalised the fact that polar antioxidants are more effective in nonpolar media, extractions of phenolic compounds in vegetable oils were inspired and achieved in this study for obtaining oils enriched in phenolic compounds. Moreover, the influence of surfactants on the extractability of phenolic compounds was experimentally studied first, followed by the small angle X-ray scattering analysis for the oil structural observation before and after extraction so as to better understand the dissolving mechanism underpinning the extraction. The results showed a significant difference on the extraction yield of phenolic compounds among oils, which was mainly dependent on their composition instead of the unsaturation of fatty acids. Appropriate surfactant additions could significantly improve extraction yield for refined sunflower oils, which 1% w/w addition of glyceryl oleate was determined as the optimal. Besides, 5% w/w addition of lecithin performed the best in oil enrichments compared with mono- and di-glycerides.

  16. Sphincter of Oddi Function and Risk Factors for Dysfunction

    PubMed Central

    Afghani, Elham; Lo, Simon K.; Covington, Paul S.; Cash, Brooks D.; Pandol, Stephen J.

    2017-01-01

    The sphincter of Oddi (SO) is a smooth muscle valve regulating the flow of biliary and pancreatic secretions into the duodenum, initially described in 1887 by the Italian anatomist, Ruggero Oddi. SO dysfunction (SOD) is a broad term referring to numerous biliary, pancreatic, and hepatic disorders resulting from spasms, strictures, and relaxation of this valve at inappropriate times. This review brings attention to various factors that may increase the risk of SOD, including but not limited to: cholecystectomy, opiates, and alcohol. Lack of proper recognition and treatment of SOD may be associated with clinical events, including pancreatitis and biliary symptoms with hepatic enzyme elevation. Pharmacologic and non-pharmacologic approaches are discussed to help recognize, prevent, and treat SOD. Future studies are needed to assess the treatment benefit of agents such as calcium-channel blockers, glyceryl trinitrate, or tricyclic antidepressants in patients with SOD. PMID:28194398

  17. Sphincter of Oddi Function and Risk Factors for Dysfunction.

    PubMed

    Afghani, Elham; Lo, Simon K; Covington, Paul S; Cash, Brooks D; Pandol, Stephen J

    2017-01-01

    The sphincter of Oddi (SO) is a smooth muscle valve regulating the flow of biliary and pancreatic secretions into the duodenum, initially described in 1887 by the Italian anatomist, Ruggero Oddi. SO dysfunction (SOD) is a broad term referring to numerous biliary, pancreatic, and hepatic disorders resulting from spasms, strictures, and relaxation of this valve at inappropriate times. This review brings attention to various factors that may increase the risk of SOD, including but not limited to: cholecystectomy, opiates, and alcohol. Lack of proper recognition and treatment of SOD may be associated with clinical events, including pancreatitis and biliary symptoms with hepatic enzyme elevation. Pharmacologic and non-pharmacologic approaches are discussed to help recognize, prevent, and treat SOD. Future studies are needed to assess the treatment benefit of agents such as calcium-channel blockers, glyceryl trinitrate, or tricyclic antidepressants in patients with SOD.

  18. Effects of ascorbic acid supplementation on male reproductive system during exposure to hypoxia

    NASA Astrophysics Data System (ADS)

    Havazhagan, G.; Riar, S. S.; Kain, A. K.; Bardhan, Jaya; Thomas, Pauline

    1989-09-01

    Two groups of male rats were exposed to simulated altitudes of 6060 m and 7576 m for 6 h/day for 7 days (intermittent exposure). In two additional groups of animals exposed to the same altitude, 100 mg of ascorbic acid (AA) was fed daily for 5 days prior to the exposure period and also during the exposure period. Rats that did not receive AA showed loss of body weight and weight of reproductive organs after exposure. Sex organs showed atrophy on histological examination and there was a deterioration in spermatozoal quality. There was an increase in alkaline and acid phosphatase, and decrease in protein, sialic acid and glyceryl phosphorylcholine content in various reproductive tissues after exposure. All the above changes in histology and biochemical composition could be partially prevented by AA supplementation. AA supplementation can therefore protect the male reproductive system from deleterious effects of hypoxia. The probable mechanism of action of AA is discussed.

  19. An overview of drugs and ancillary equipment for the dentist's emergency kit.

    PubMed

    Chapman, P J

    2003-06-01

    The concept of a basic (i.e., essential) medical emergency kit suitable for a general dental practitioner varies somewhat between different authorities. A practitioner's choice is also dependant on the proximity of medical aid and the nature of the dental practice. Over recent years the trend has been to restrict the items to a minimum, in the interest of both common sense and safety, for example, just oxygen, adrenaline 1:1000, an oral carbohydrate source, glyceryl trinitrate and aspirin as first options. Ancillary equipment should include an oxygen therapy facemask, a pocket mask and a set of oral (Guedel) airways. Two further medication options for consideration are an aerosol bronchodilator and, in certain circumstances, an injectable antihypoglycaemic agent. This paper provides a selective overview of the subject. An absolute necessity is for dentists to be competent in Basic Life Support skills, and to maintain a complete and current medical history for all patients.

  20. Agents that activate protein kinase C reduce acetylcholine sensitivity in cultured myotubes

    PubMed Central

    1985-01-01

    We have examined acetylcholine (ACh)-elicited potentials or currents in current- or voltage-clamped cultured myotubes exposed to 12-O- tetradecanoyl-phorbol-13-acetate (TPA), a potent tumor promoter that activates protein kinase C. Although this agent had little action on either membrane resting potential or electrical resistance, a reversible decrease in ACh sensitivity was induced on 3-4-d-old chick myotubes. Depression of transmitter action by TPA was extended to 7-8-d mouse myotubes only when they were treated with phosphatidylserine. Glyceryl dioleate had effects on myotubes similar to those of TPA but with a reduced efficacy. We conclude that the activation of protein kinase C might be involved with the capacity of ACh receptors to respond to transmitter stimulation. PMID:3156868

  1. Composition of the silk lipids of the spider Nephila clavipes.

    PubMed

    Schulz, S

    2001-06-01

    A 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.

  2. Three-dimensional solubility parameters and their use in characterising the permeation of drugs through the skin.

    PubMed

    Groning, R; Braun, F J

    1996-05-01

    The physico-chemical properties of drug substances are major determinants of their transdermal absorption. In the present study the concept of the three-dimensional solubility parameters of Hansen was applied in conjunction with the Bagley projection to describe the permeation of drugs and model substances through the skin. Drug permeation data from the literature were compared with the calculated solubility parameters of the drugs. It was demonstrated that the permeation of drugs can be estimated by their position in the Bagley diagram. There is a linear correlation between the logarithm of the skin permeation of drugs and the exchange cohesive energy for the steroids testosterone, progesterone, hydrocortisone acetate, corticosterone, cortisone, and dexamethasone. A linear correlation can be confirmed for the permeation of glyceryl trinitrate, digitoxin, oestradiol, scopolamine, atropine, diethylcarbamazine, fentanyl, and chlorpheniramine. In the case of morphine, codeine, sufentanil, meperidine and hydromorphone there is a linear relationship, too.

  3. Regulation of Human Mitochondrial Aldehyde Dehydrogenase (ALDH-2) Activity by Electrophiles in Vitro*

    PubMed Central

    Oelze, Matthias; Knorr, Maike; Schell, Richard; Kamuf, Jens; Pautz, Andrea; Art, Julia; Wenzel, Philip; Münzel, Thomas; Kleinert, Hartmut; Daiber, Andreas

    2011-01-01

    Recently, mitochondrial aldehyde dehydrogenase (ALDH-2) was reported to reduce ischemic damage in an experimental myocardial infarction model. ALDH-2 activity is redox-sensitive. Therefore, we here compared effects of various electrophiles (organic nitrates, reactive fatty acid metabolites, or oxidants) on the activity of ALDH-2 with special emphasis on organic nitrate-induced inactivation of the enzyme, the biochemical correlate of nitrate tolerance. Recombinant human ALDH-2 was overexpressed in Escherichia coli; activity was determined with an HPLC-based assay, and reactive oxygen and nitrogen species formation was determined by chemiluminescence, fluorescence, protein tyrosine nitration, and diaminonaphthalene nitrosation. The organic nitrate glyceryl trinitrate caused a severe concentration-dependent decrease in enzyme activity, whereas incubation with pentaerythritol tetranitrate had only minor effects. 4-Hydroxynonenal, an oxidized prostaglandin J2, and 9- or 10-nitrooleate caused a significant inhibition of ALDH-2 activity, which was improved in the presence of Mg2+ and Ca2+. Hydrogen peroxide and NO generation caused only minor inhibition of ALDH-2 activity, whereas peroxynitrite generation or bolus additions lead to severe impairment of the enzymatic activity, which was prevented by the thioredoxin/thioredoxin reductase (Trx/TrxR) system. In the presence of glyceryl trinitrate and to a lesser extent pentaerythritol tetranitrate, ALDH-2 may be switched to a peroxynitrite synthase. Electrophiles of different nature potently regulate the enzymatic activity of ALDH-2 and thereby may influence the resistance to ischemic damage in response to myocardial infarction. The Trx/TrxR system may play an important role in this process because it not only prevents inhibition of ALDH-2 but is also inhibited by the ALDH-2 substrate 4-hydroxynonenal. PMID:21252222

  4. Comparison of metoprolol tartrate multiple-unit lipid matrix systems produced by different technologies.

    PubMed

    Aleksovski, Aleksandar; Van Bockstal, Pieter-Jan; Roškar, Robert; Sovány, Tamás; Regdon, Géza; De Beer, Thomas; Vervaet, Chris; Dreu, Rok

    2016-06-10

    The aim of this study was to develop, evaluate and compare extended release mini-matrices based on metoprolol tartrate (MPT) and either glyceryl behenate (GB) or glyceryl palmitostearate (GPS). Mini-matrices were produced by three different techniques: hot melt extrusion, compression of melt granulates and prilling. Hot-melt extrusion and compression of granules obtained from melted material proved to be reliable, robust and reproducible techniques with aim of obtaining extended release matrices. Prilling tended to be susceptible to increased melt viscosity. Direct compression was not applicable for mini-matrix production due to poor powder flow. In general MPT release from all matrices was affected by its loading and the size of the units/particles. Processing of GB-MPT mixtures by different techniques did not lead to different drug release rates and patterns, while in case of GPS differently obtained matrices provided diverse MPT release outcomes. Matrices based on GB tended to have higher porosity compared to ones composed of GPS and thus most of the GB-based formulations showed faster drug delivery. FT-IR analysis revealed no interactions between primary components used for matrix production and Raman mapping outlined uniform MPT distribution throughout the units. DSC and X-ray studies revealed significant changes in the crystallinity of glycerides after storage under room conditions (GPS samples) and at increased temperature (GB and GPS samples), which was correlated to the changes seen in drug release rate and pattern after storage. Media composition in general tended to insignificantly affect GB matrices, while in case of GPS matrices increasing the pH and presence of biorelevant compounds induced faster drug release.

  5. Spheronization of solid lipid extrudates: A novel approach on controlling critical process parameters.

    PubMed

    Petrovick, Gustavo Freire; Pein, Miriam; Thommes, Markus; Breitkreutz, Jörg

    2015-05-01

    Solid lipids are non-toxic excipients, which are known to potentially enhance delivery and bioavailability of poorly water-soluble drugs and moreover to mask unpleasant tasting drugs. Multiple unit matrix dosage forms based on solid lipids, such as lipid pellets, can be obtained by solvent-free cold extrusion and spheronization. This method presents advantages in the processing of sensitive substances, such as low process temperatures, the absence of solvents and a drying step. However, the material temperature during the spheronization showed to be critical so far. The process leads to increased material temperatures, causing particle agglomeration and discontinuity of the spheronization. In the present study, extrudates of 0.5mm in diameter containing metformin hydrochloride, and either semisynthetic hard fat (Witocan® 42/44) or different ternary mixtures based on hard fat, glyceryl trimyristate, and glyceryl distearate, were spheronized. By applying common process parameters, particle agglomeration or material stickiness on equipment walls was observed in preliminary experiments after 2-6min, depending on the lipid composition. Therefore, an innovative instrumental setup to control the spheronization process was developed utilizing an infrared light source, which was positioned over the particle bed. The new approach enabled a spheronization process that reached the desired spheronization temperature after 2-3min and neither particle agglomeration nor material adherence occurred even after longer process times. The different formulations, even those based on high amount of solid lipids, were successfully spheronized over 15min, resulting in small diameter lipid pellets with smooth surface and aspect ratios below 1.3.

  6. Formulation Development, Process Optimization, and In Vitro Characterization of Spray-Dried Lansoprazole Enteric Microparticles

    PubMed Central

    Vora, Chintan; Patadia, Riddhish; Mittal, Karan; Mashru, Rajashree

    2016-01-01

    This research focuses on the development of enteric microparticles of lansoprazole in a single step by employing the spray drying technique and studies the effects of variegated formulation/process variables on entrapment efficiency and in vitro gastric resistance. Preliminary trials were undertaken to optimize the type of Eudragit and its various levels. Further trials included the incorporation of plasticizer triethyl citrate and combinations of other polymers with Eudragit S 100. Finally, various process parameters were varied to investigate their effects on microparticle properties. The results revealed Eudragit S 100 as the paramount polymer giving the highest gastric resistance in comparison to Eudragit L 100-55 and L 100 due to its higher pH threshold and its polymeric backbone. Incorporation of plasticizer not only influenced entrapment efficiency, but diminished gastric resistance severely. On the contrary, polymeric combinations reduced entrapment efficiency for both sodium alginate and glyceryl behenate, but significantly influenced gastric resistance for only sodium alginate and not for glyceryl behenate. The optimized process parameters were comprised of an inlet temperature of 150°C, atomizing air pressure of 2 kg/cm2, feed solution concentration of 6% w/w, feed solution spray rate of 3 ml/min, and aspirator volume of 90%. The SEM analysis revealed smooth and spherical shape morphologies. The DSC and PXRD study divulged the amorphous nature of the drug. Regarding stability, the product was found to be stable under 3 months of accelerated and long-term stability conditions as per ICH Q1A(R2) guidelines. Thus, the technique offers a simple means to generate polymeric enteric microparticles that are ready to formulate and can be directly filled into hard gelatin capsules. PMID:27222612

  7. Self-Assembled Cubic Liquid Crystalline Nanoparticles for Transdermal Delivery of Paeonol

    PubMed Central

    Li, Jian-Chun; Zhu, Na; Zhu, Jin-Xiu; Zhang, Wen-Jing; Zhang, Hong-Min; Wang, Qing-Qing; Wu, Xiao-Xiang; Wang, Xiu; Zhang, Jin; Hao, Ji-Fu

    2015-01-01

    Background The aim of this study was to optimize the preparation method for self-assembled glyceryl monoolein-based cubosomes containing paeonol and to characterize the properties of this transdermal delivery system to improve the drug penetration ability in the skin. Material/Methods In this study, the cubic liquid crystalline nanoparticles loaded with paeonol were prepared by fragmentation of glyceryl monoolein (GMO)/poloxamer 407 bulk cubic gel by high-pressure homogenization. We evaluated the Zeta potential of these promising skin-targeting drug-delivery systems using the Malvern Zeta sizer examination, and various microscopies and differential scanning calorimetry were also used for property investigation. Stimulating studies were evaluated based on the skin irritation reaction score standard and the skin stimulus intensity evaluation standard for paeonol cubosomes when compared with commercial paeonol ointment. In vitro tests were performed on excised rat skins in an improved Franz diffusion apparatus. The amount of paeonol over time in the in vitro penetration and retention experiments both was determined quantitatively by HPLC. Results Stimulating studies were compared with the commercial ointment which indicated that the paeonol cubic liquid crystalline nanoparticles could reduce the irritation in the skin stimulating test. Thus, based on the attractive characteristics of the cubic crystal system of paeonol, we will further exploit the cosmetic features in the future studies. Conclusions The transdermal delivery system of paeonol with low-irritation based on the self-assembled cubic liquid crystalline nanoparticles prepared in this study might be a promising system of good tropical preparation for skin application. PMID:26517086

  8. Controlled release of oral tetrahydrocurcumin from a novel self-emulsifying floating drug delivery system (SEFDDS).

    PubMed

    Setthacheewakul, Saipin; Kedjinda, Wichan; Maneenuan, Duangkhae; Wiwattanapatapee, Ruedeekorn

    2011-03-01

    The objectives of this study were to develop and evaluate a novel self-emulsifying floating drug delivery system (SEFDDS) that resulted in improved solubility, dissolution, and controlled release of the poorly water-soluble tetrahydrocurcumin (THC). The formulations of liquid self-emulsifying drug delivery system (SEDDS; mixtures of Labrasol, Cremophor EL, Capryol 90, Labrafac PG) were optimized by solubility assay and pseudo-ternary phase diagram analysis. The liquid SEDDS was mixed with adsorbent (silicon dioxide), glyceryl behenate, pregelatinized starch, sodium starch glycolate, and microcrystalline cellulose and transformed into pellets by the extrusion/spheronization technique. The resulting pellets with 22% liquid SEDDS had a uniform size and good self-emulsification property. The microemulsions in aqueous media of different self-emulsifying floating pellet formulations were in a particle size range of 25.9-32.5 nm. Use of different weight proportions of glyceryl behenate and sodium starch glycolate in pellet formulations had different effects on the floating abilities and in vitro drug release. The optimum formulation (F2) had a floating efficiency of 93% at 6 h and provided a controlled release of THC over an 8-h period. The release rate and extent of release of THC liquid SEDDS (80% within 2 h) and self-emulsifying floating pellet formulation (80% within 8 h) were significantly higher than that of unformulated THC (only 30% within 8 h). The pellet formulation was stable under intermediate and accelerated storage conditions for up to 6 months. Controlled release from this novel SEFDDS can be a useful alternative for the strategic development of oral solid lipid-based formulations.

  9. Effect of arvanil (N-arachidonoyl-vanillyl-amine), a nonpungent anandamide-capsaicin hybrid, on ion currents in NG108-15 neuronal cells.

    PubMed

    Lo, Yuk-Keung; Chiang, Hung-Ting; Wu, Sheng-Nan

    2003-02-15

    The effects of arvanil (N-arachidonoyl-vanillyl-amine), a structural hybrid between capsaicin and anandamide, on ion currents in a mouse neuroblastoma and rat glioma hybrid cell line, NG108-15, were examined with the aid of the whole-cell voltage-clamp technique. Arvanil (0.2-50 microM) caused an inhibition of voltage-dependent L-type Ca(2+) current (I(Ca,L)) in a concentration-dependent manner. Arvanil produced no change in the overall shape of the current-voltage relationship of I(Ca,L). The IC(50) value of arvanil-induced inhibition of I(Ca,L) was 2 microM. Arvanil (5 microM) could shift the steady-state inactivation curve of I(Ca,L) to a more negative potential by approximately -15mV. No effect of arvanil (20 microM) on delayed rectifier K(+) current (I(K(DR))) was observed; however, capsaicin (20 microM), glyceryl nonivamide (20 microM) and capsinolol (20 microM) suppressed it significantly. Arvanil (20 microM) caused a slight reduction in the amplitude of erg (ether-à-go-go-related)-mediated K(+) current (I(K(erg))) without modifying the activation curve of this current, while capsaicin and glyceryl nonivamide were more effective in suppressing I(K(erg)). Under current-clamp configuration, arvanil decreased the firing frequency of action potentials. Arvanil-mediated inhibition of I(Ca,L) appeared to be independent of its binding to either vanilloid or cannabinoid receptors. The channel-blocking properties of arvanil may, at least in part, contribute to the underlying mechanisms by which it affects neuronal or neuroendocrine function.

  10. Quantitative microleakage of some dentinal bonding restorative systems.

    PubMed

    Hasegawa, T; Retief, D H

    1993-03-01

    The quantitative microleakage of class V cementum (dentin) cavities restored with six dentinal bonding restorative systems was determined in vitro. Ninety extracted human permanent first and second mandibular and maxillary premolars were used in this study. Class V preparations were made in cementum (dentin) at the root facial surfaces. The preparations were restored with 1) a dentin bonding system containing 2% HEMA and BisGMA and a light-cured microfilled composite; 2) the same materials only substituting META/MMA base and TBB catalyst monomers for the BisGMA sealer; 3) a dentin bonding system containing 35% HEMA with META/MMA base and TBB catalyst, and a light-cured hybrid composite; 5) the same dentin bonding system only substituting the 35% glycerylmethacrylate for the 35% HEMA and using the microfilled composite; and 6) the previously described system with a substitution of 0.5 mol EDTA for the 10% citric acid -3% FeCl3. Fifteen teeth were restored with each procedure. The restorations were finished with 12-bladed carbide burs 15 min after placement, the teeth were stored in saline at 37 degrees C for 24 h, finished with Sof-Lex discs and then thermocycled in 2% methylene blue solution 500 times between 50 degrees C and 8 degrees C with a dwell time of 15 s. Quantitative microleakage was determined by a spectrophotometric dye-recovery method and expressed in microgram/dye/restoration. The data were analyzed by ANOVA, Student-Newman-Keuls and Kruskal-Wallis tests. The quantitative microleakage of the teeth restored with the adhesive systems containing 35% glyceryl methacrylate was significantly reduced. The bonding mechanism of glyceryl methacrylate is not known.

  11. Targeted delivery of a model immunomodulator to the lymphatic system: comparison of alkyl ester versus triglyceride mimetic lipid prodrug strategies.

    PubMed

    Han, Sifei; Quach, Tim; Hu, Luojuan; Wahab, Anisa; Charman, William N; Stella, Valentino J; Trevaskis, Natalie L; Simpson, Jamie S; Porter, Christopher J H

    2014-03-10

    A lipophilic prodrug approach has been used to promote the delivery of a model immunomodulator, mycophenolic acid (MPA), to the lymphatic system after oral administration. Lymphatic transport was employed to facilitate enhanced drug uptake into lymphocytes, as recent studies demonstrate that targeted drug delivery to lymph resident lymphocytes may enhance immunomodulatory effects. Two classes of lymph-directing prodrugs were synthesised. Alkyl chain derivatives (octyl mycophenolate, MPA-C8E; octadecyl mycophenolate, MPA-C18E; and octadecyl mycophenolamide, MPA-C18AM), to promote passive partitioning into lipids in lymphatic transport pathways, and a triglyceride mimetic prodrug (1,3-dipalmitoyl-2-mycophenoloyl glycerol, 2-MPA-TG) to facilitate metabolic integration into triglyceride deacylation-reacylation pathways. Lymphatic transport, lymphocyte uptake and plasma pharmacokinetics were assessed in mesenteric lymph and carotid artery cannulated rats following intraduodenal infusion of lipid-based formulations containing MPA or MPA prodrugs. Patterns of prodrug hydrolysis in rat digestive fluid, and cellular re-esterification in vivo, were evaluated to examine the mechanisms responsible for lymphatic transport. Poor enzyme stability and low absorption appeared to limit lymphatic transport of the alkyl derivatives, although two of the three alkyl chain prodrugs - MPA-C18AM (6-fold) and MPA-C18E (13-fold) still increased lymphatic drug transport when compared to MPA. In contrast, 2-MPA-TG markedly increased lymphatic drug transport (80-fold) and drug concentrations in lymphocytes (103-fold), and this was achieved via biochemical incorporation into triglyceride deacylation-reacylation pathways. The prodrug was hydrolysed rapidly to 2-mycophenoloyl glycerol (2-MPA-MG) in the presence of rat digestive fluid, and 2-MPA-MG was subsequently re-esterified in the enterocyte with oleic acid (most likely originating from the co-administered formulation) prior to accessing the

  12. Restricted access magnetic materials prepared by dual surface modification for selective extraction of therapeutic drugs from biological fluids

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Wang, Yuxia; Chen, Lei; Wan, Qian-Hong

    2012-02-01

    Magnetic porous particles with dual functionality have been prepared by a two-step procedure and evaluated as novel restricted access materials for extraction of therapeutic agents from biological fluids. The magnetic silica particles served as scaffolds were first modified with diol groups, which were then converted to octadecyl esters through reaction with stearoyl chloride. In the second step, the octadecyl esters on the exterior surface were hydrolyzed by the action of lipase to yield magnetic particles with hydrophobic reversed-phase ligands on the inner surface and biocompatible diol groups on the outer surface. The restricted access behavior of the resulting materials was confirmed by differential binding of small molecules such as methotrexate (MTX), leucovorin (LV) and folic acid (FA) relative to bovine serum albumin. While MTX, LV and FA were all bound to the magnetic particles with high affinity, the adsorption of the protein was markedly reduced due to size exclusion effect. The utility of the magnetic particles for sample preparation was tested in solid-phase extraction of MTX, LV and FA from spiked human serum and the effects of the SPE conditions on the recovery of the analytes were systematically studied. Moreover, the magnetic particle-based sample preparation procedure coupled with reversed-phase liquid chromatography analysis was validated in terms of specificity, linearity and reproducibility. The method was shown to be free from interference of endogenous compounds and linear over the concentration range of 0.5-10 μg/mL for the three drugs studied. The limits of detection for the three drugs in serum were in the range of 0.160-0.302 μg/mL. Reproducibility expressed as the RSD of the recovery for ten replicated extractions at three different concentrations was found to be less than 8.93%. With a unique combination of surface functionality with magnetic cores, the restricted access magnetic particles may be adapted in automated and high

  13. Multi-proxy geochemical analyses of Indus Submarine Fan sediments sampled by IODP Expedition 355: implications for sediment provenance and palaeoclimate reconstructions

    NASA Astrophysics Data System (ADS)

    Bratenkov, Sophia; George, Simon C.; Bendle, James; Liddy, Hannah; Clift, Peter D.; Pandey, Dhananjai K.; Kulhanek, Denise K.; Andò, Sergio; Tiwari, Manish; Khim, Boo-Keun; Griffith, Elizabeth; Steinke, Stephan; Suzuki, Kenta; Lee, Jongmin; Newton, Kate; Tripathi, Shubham; Expedition 355 Scientific Party

    2016-04-01

    petrography and heavy mineral analysis, geochemical data, isotope composition, and biomarker analysis. Preliminary organic geochemistry data suggest an increase of terrigenous organic matter input into sediment starting around 10.5 Ma, with a strong decrease in the last 1 Ma. Moreover, the detailed analyses of the glyceryl dialkyl glyceryl tetraether (GDGT) and alkenone lipids provide the first sea surface temperature (SST) reconstructions in the region. These data indicate decreasing SST from the Middle Miocene Climatic Optimum until today. This research provides an exceptional opportunity to apply a multiproxy approach to understand sediment provenance, erosional processes, and palaeoclimate evolution in the eastern Arabian Sea.

  14. Preparation and evaluation of a self-nanoemulsifying drug delivery system loaded with Akebia saponin D–phospholipid complex

    PubMed Central

    Shen, Jinyang; Bi, Jianping; Tian, Hongli; Jin, Ye; Wang, Yuan; Yang, Xiaolin; Yang, Zhonglin; Kou, Junping; Li, Fei

    2016-01-01

    Background Akebia saponin D (ASD) exerts various pharmacological activities but with poor oral bioavailability. In this study, a self-nanoemulsifying drug delivery system (SNEDDS) based on the drug–phospholipid complex technique was developed to improve the oral absorption of ASD. Methods ASD–phospholipid complex (APC) was prepared using a solvent-evaporation method and characterized by infrared spectroscopy, differential scanning calorimetry, morphology observation, and solubility test. Oil and cosurfactant were selected according to their ability to dissolve APC, while surfactant was chosen based on its emulsification efficiency in SNEDDS. Pseudoternary phase diagrams were constructed to determine the optimized APC-SNEDDS formulation, which was characterized by droplet size determination, zeta potential determination, and morphology observation. Robustness to dilution and thermodynamic stability of optimized formulation were also evaluated. Subsequently, pharmacokinetic parameters and oral bioavailability of ASD, APC, and APC-SNEDDS were investigated in rats. Results The liposolubility significantly increased 11.4-fold after formation of APC, which was verified by the solubility test in n-octanol. Peceol (Glyceryl monooleate [type 40]), Cremophor® EL (Polyoxyl 35 castor oil), and Transcutol HP (Diethylene glycol monoethyl ether) were selected as oil, surfactant, and cosurfactant, respectively. The optimal formulation was composed of Glyceryl monooleate (type 40), Polyoxyl 35 castor oil, Diethylene glycol monoethyl ether, and APC (1:4.5:4.5:1.74, w/w/w/w), which showed a particle size of 148.0±2.7 nm and a zeta potential of −13.7±0.92 mV after dilution with distilled water at a ratio of 1:100 (w/w) and good colloidal stability. Pharmacokinetic studies showed that APC-SNEDDS exhibited a significantly greater Cmax1 (733.4±203.8 ng/mL) than ASD (437.2±174.2 ng/mL), and a greater Cmax2 (985.8±366.6 ng/mL) than ASD (180.5±75.1 ng/mL) and APC (549.7±113

  15. Formulation and in vitro release evaluation of newly synthesized palm kernel oil esters-based nanoemulsion delivery system for 30% ethanolic dried extract derived from local Phyllanthus urinaria for skin antiaging

    PubMed Central

    Mahdi, Elrashid Saleh; Noor, Azmin Mohd; Sakeena, Mohamed Hameem; Abdullah, Ghassan Z; Abdulkarim, Muthanna F; Sattar, Munavvar Abdul

    2011-01-01

    Background Recently there has been a remarkable surge of interest about natural products and their applications in the cosmetic industry. Topical delivery of antioxidants from natural sources is one of the approaches used to reverse signs of skin aging. The aim of this research was to develop a nanoemulsion cream for topical delivery of 30% ethanolic extract derived from local Phyllanthus urinaria (P. urinaria) for skin antiaging. Methods Palm kernel oil esters (PKOEs)-based nanoemulsions were loaded with P. urinaria extract using a spontaneous method and characterized with respect to particle size, zeta potential, and rheological properties. The release profile of the extract was evaluated using in vitro Franz diffusion cells from an artificial membrane and the antioxidant activity of the extract released was evaluated using the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method. Results Formulation F12 consisted of wt/wt, 0.05% P. urinaria extract, 1% cetyl alcohol, 0.5% glyceryl monostearate, 12% PKOEs, and 27% Tween® 80/Span® 80 (9/1) with a hydrophilic lipophilic balance of 13.9, and a 59.5% phosphate buffer system at pH 7.4. Formulation F36 was comprised of 0.05% P. urinaria extract, 1% cetyl alcohol, 1% glyceryl monostearate, 14% PKOEs, 28% Tween® 80/Span® 80 (9/1) with a hydrophilic lipophilic balance of 13.9, and 56% phosphate buffer system at pH 7.4 with shear thinning and thixotropy. The droplet size of F12 and F36 was 30.74 nm and 35.71 nm, respectively, and their nanosizes were confirmed by transmission electron microscopy images. Thereafter, 51.30% and 51.02% of the loaded extract was released from F12 and F36 through an artificial cellulose membrane, scavenging 29.89% and 30.05% of DPPH radical activity, respectively. Conclusion The P. urinaria extract was successfully incorporated into a PKOEs-based nanoemulsion delivery system. In vitro release of the extract from the formulations showed DPPH radical scavenging activity. These formulations can

  16. Chemical composition and anti-inflammatory activities of the essential oils from Acacia mearnsii de Wild.

    PubMed

    Avoseh, Opeyemi N; Oyedeji, Ope-oluwa O; Aremu, Kayode; Nkeh-Chungag, Benedicta N; Songca, Sandile P; Oluwafemi, Samuel O; Oyedeji, Adebola O

    2015-01-01

    The volatile oils of the leaves and the stem bark of Acacia mearnsii de Wild obtained by hydro-distillation were analysed by gas chromatography-mass spectrometry. A total of 20, 38, 29 and 38 components accounted for 93.8%, 92.1%, 78.5% and 90.9% of the total oils of the fresh, dry leaves and fresh, dry stem bark, respectively. The major components of the oil were octadecyl alcohol (25.5%) and phytol (10.5%); cis-verbenol (29.5%); phytol (10.1%) and phytol (23.4%) for the fresh leaves, dried leaves, fresh stem, dry stem bark, respectively. Oral administration of essential oils at a dose of 2% showed significant (p < 0.05) anti-inflammatory properties in the albumin-induced test model in rats. Oils from the fresh leaves and dry stems inhibited inflammation beyond 4 h post treatment. The potent anti-inflammatory activity of essential oils of A. mearnsii hereby confirmed its traditional use in treating various inflammatory diseases.

  17. Mechanistic study for immobilization of cysteine-labeled oligopeptides on UV-activated surfaces.

    PubMed

    Ong, Lian Hao; Ding, Xiaokang; Yang, Kun-Lin

    2014-10-01

    In this study, we report immobilization of cysteine-labeled oligopeptides on UV activated surfaces decorated with N,N-dimethyl-n-octadecyl-3-aminopropyltrimethoxysilyl chloride (DMOAP). Our result shows that cysteine group, regardless of its position in the oligopeptide, is essential for successful immobilization of oligopeptide on the UV-activated surface. A possible reaction mechanism is nucleophilic addition of thiolates to surface aldehyde groups generated during UV activation. By using this technique, we are able to incorporate anchoring points into oligopeptides through cysteine residues. Furthermore, immobilized oligopeptides on the UV-activated surface is very stable even under harsh washing conditions. Finally, we show that an HPQ-containing oligopeptide can be immobilized on the UV-activated surface, but the final surface density and its ability to bind streptavidin are affected by the position of cysteine and HPQ. An oligopeptide with a cysteine at the N-terminus and a HPQ motif at the C-terminus gives the highest binding signal in the streptavidin-binding assay. This result is potentially useful for the development of functional oligopeptide microarrays for detecting target protein molecules.

  18. Collective fluorescence switching of counterion-assembled dyes in polymer nanoparticles.

    PubMed

    Reisch, Andreas; Didier, Pascal; Richert, Ludovic; Oncul, Sule; Arntz, Youri; Mély, Yves; Klymchenko, Andrey S

    2014-06-09

    The current challenge in the field of fluorescent nanoparticles (NPs) for bioimaging is to achieve extreme brightness and external control of their emission using biodegradable materials. Here we propose a new concept of fluorescent polymer NPs, doped with ionic liquid-like salts of a cationic dye (octadecyl rhodamine B) with a bulky hydrophobic counterion (fluorinated tetraphenylborate) that serves as spacer minimizing dye aggregation and self-quenching. The obtained 40-nm poly(D,L-lactide-co-glycolide) NPs containing up to 500 dyes are brighter than quantum dots and exhibit photo-induced reversible on/off fluorescence switching, never reported for dye-doped NPs. We show that this collective switching of hundreds of dyes is due to ultrafast excitation energy transfer and can be used for super-resolution imaging. These NPs, being spontaneously endocytosed by living cells, feature high signal-to-noise ratio and absence of toxicity. The counterion-based concept opens the way to a new class of nanomaterials for sensing, imaging and light harvesting.

  19. Activation of the Kelch-like ECH-associated protein 1 (Keap1)/NF-E2-related factor 2 (Nrf2) pathway through covalent modification of the 2-alkenal group of aliphatic electrophiles in Coriandrum sativum L.

    PubMed

    Abiko, Yumi; Mizokawa, Mai; Kumagai, Yoshito

    2014-11-12

    Phytochemicals able to activate the transcription factor NF-E2-related factor 2 (Nrf2) were isolated from an extract of Coriandrum sativum L. (C. sativum) leaves by preparative octadecyl silica column chromatography. Ultraperformance liquid chromatography and liquid chromatography-tandem mass spectrometry analysis of the isolated components after derivatization with 2-diphenylacetyl-1,3-inandione-1-hydrazone and experiments with HepG2 cells revealed that (E)-2-alkenals with different carbon numbers play a role in Nrf2 activation in these cells. Such Nrf2 activation appears to be attributable to S-alkylation of Kelch-like ECH-associated protein 1 (Keap1), the negative regulator for Nrf2, as determined by a biotin-PEAC5-maleimide assay. Interestingly, (E)-2-butenal caused Keap1 modification and Nrf2 activation, whereas butanal did not. These results suggest that (E)-2-alkenals with an α,β-unsaturated aldehyde moiety, which is a common substituent in phytochemicals isolated from C. sativum leaves, activate the Keap1/Nrf2 pathway associated with cellular protection.

  20. New analytical method for the determination of musks in personal care products by Quick, Easy, Cheap, Effective, Rugged, and Safe extraction followed by GC-MS.

    PubMed

    Homem, Vera; Silva, José Avelino; Cunha, Carina; Alves, Arminda; Santos, Lúcia

    2013-07-01

    Synthetic musks are organic compounds used as fragrance additives and fixative compounds in a diversity of personal care products. A new method based on quick, easy, cheap, effective, rugged, and safe (QuEChERS) extraction followed by GC-MS for the analysis of 12 musks in personal care products was developed and validated. Some experimental parameters, such as total QuEChERS mass, sample mass/solvent volume ratio, type of extraction solvent, as well as salts and sorbents amount were investigated and optimized. The final method involves the musks extraction using acetonitrile, followed by the addition of anhydrous magnesium sulphate and sodium acetate. The clean-up step was performed using dispersive SPE with primary and secondary amine and octadecyl-silica sorbents. This extraction procedure is fast (about 10 min) when compared to other traditional approaches. The method was robust for the matrices studied and shows a high precision (%RSD < 15%) and accuracy (average recovery of 85%), allowing the detection of musks in minimum concentrations between 0.01 ng/g (galaxolide) and 15.80 ng/g (musk xylene). The developed method was applied to the analysis of 12 samples, which revealed musks concentrations ranging from 2 ng/g (toothpaste) to 882,340 ng/g (perfumed body lotion).

  1. Hydrophobic high surface area zeolites derived from fly ash for oil spill remediation.

    PubMed

    Sakthivel, Tamilselvan; Reid, David L; Goldstein, Ian; Hench, Larry; Seal, Sudipta

    2013-06-04

    Fly ash, a coal combustion byproduct with a predominantly aluminosilicate composition, is modified to develop an inexpensive sorbent for oil spill remediation. The as-produced fly ash is a hydrophilic material with poor sorption capacity. A simple two-step chemical modification process is designed to improve the oil sorption capacity. First, the fly ash was transformed to a zeolitic material via an alkali treatment, which increased the specific surface area up to 404 m(2) g(-1). Then, the material was surface functionalized to form a hydrophobic material with high contact angle up to 147° that floats on the surface of an oil-water mixture. The reported oil sorption capacities of X-type zeolite sorbent with different surface functionalization (propyl-, octyl-, octadecyl-trimethoxysilane and esterification) were estimated to 1.10, 1.02, 0.86, and 1.15 g g(-1), respectively. Oil sorption was about five times higher than the as-received fly ash (0.19 g g(-1)) and also had high buoyancy critical for economic cleanup of oil over water.

  2. Microstructure and rheology of a thermoreversible gel under large amplitude oscillatory shear (LAOS) deformation using time-resolved oscillatory rheo-small-angle neutron scattering (tOr-SANS)

    NASA Astrophysics Data System (ADS)

    Kim, Jung Min; Gurnon, A. Kate; Wagner, Norman; Eberle, Aaron

    2013-03-01

    Large amplitude oscillatory shear (LAOS) rheology is an effective way of studying the nonlinear dynamics of complex fluids. Here, we present a new method for a direct, quantitative study of the microstructure under LAOS deformation in the framework of the alignment factor, Af. We use a model thermoreversible adhesive hard-sphere system composed of octadecyl-coated silica particles suspended in n-tetradecane. With temperature the particle potential is controlled and the system is shifted from behaving as a near hard-sphere to an adhesive hard-sphere system leading to aggregation and ultimately a dynamical arrest transition to macroscopic gelation. Time-resolved oscillatory rheo-small-angle neutron scattering (tOr-SANS) measurements in the 1-3 plane are performed by stroboscopically probing the structural evolution as a function of time during LAOS. Under strong shear, the 2D scattering pattern of the system in the gelled state exhibits a strong anisotropy commonly known as a ``butterfly'' pattern, which corresponds to the stretching of the microstructure along the flow direction. The first structure-Lissajous plots of this model system are presented in terms of an order parameter and Af as a function of instantaneous strain and strain rate. This new analysis demonstrates a novel method for simultaneously measuring the rheology and microstructure during a time-dependent deformation (LAOS).

  3. Different assembly of type IV collagen on hydrophilic and hydrophobic substrata alters endothelial cells interaction.

    PubMed

    Coelho, N Miranda; González-García, C; Planell, J A; Salmerón-Sánchez, M; Altankov, G

    2010-06-09

    Considering the structural role of type IV collagen (Col IV) in the assembly of the basement membrane (BM) and the perspective of mimicking its organization for vascular tissue engineering purposes, we studied the adsorption pattern of this protein on model hydrophilic (clean glass) and hydrophobic trichloro(octadecyl)silane (ODS) surfaces known to strongly affect the behavior of other matrix proteins. The amount of fluorescently labeled Col IV was quantified showing saturation of the surface for concentration of the adsorbing solution of about 50microg/ml, but with approximately twice more adsorbed protein on ODS. AFM studies revealed a fine - nearly single molecular size - network arrangement of Col IV on hydrophilic glass, which turns into a prominent and growing polygonal network consisting of molecular aggregates on hydrophobic ODS. The protein layer forms within minutes in a concentration-dependent manner. We further found that human umbilical vein endothelial cells (HUVEC) attach less efficiently to the aggregated Col IV (on ODS), as judged by the significantly altered cell spreading, focal adhesions formation and the development of actin cytoskeleton. Conversely, the immunofluorescence studies for integrins revealed that the fine Col IV network formed on hydrophilic substrata is better recognized by the cells via both alpha1 and alpha2 heterodimers which support cellular interaction, apart from these on hydrophobic ODS where almost no clustering of integrins was observed.

  4. Collective fluorescence switching of counterion-assembled dyes in polymer nanoparticles

    NASA Astrophysics Data System (ADS)

    Reisch, Andreas; Didier, Pascal; Richert, Ludovic; Oncul, Sule; Arntz, Youri; Mély, Yves; Klymchenko, Andrey S.

    2014-06-01

    The current challenge in the field of fluorescent nanoparticles (NPs) for bioimaging is to achieve extreme brightness and external control of their emission using biodegradable materials. Here we propose a new concept of fluorescent polymer NPs, doped with ionic liquid-like salts of a cationic dye (octadecyl rhodamine B) with a bulky hydrophobic counterion (fluorinated tetraphenylborate) that serves as spacer minimizing dye aggregation and self-quenching. The obtained 40-nm poly(D,L-lactide-co-glycolide) NPs containing up to 500 dyes are brighter than quantum dots and exhibit photo-induced reversible on/off fluorescence switching, never reported for dye-doped NPs. We show that this collective switching of hundreds of dyes is due to ultrafast excitation energy transfer and can be used for super-resolution imaging. These NPs, being spontaneously endocytosed by living cells, feature high signal-to-noise ratio and absence of toxicity. The counterion-based concept opens the way to a new class of nanomaterials for sensing, imaging and light harvesting.

  5. Cytotoxic and ACAT-inhibitory sesquiterpene lactones from the root of Ixeris dentata forma albiflora.

    PubMed

    Ahn, Eun-Mi; Bang, Myun-Ho; Song, Myoung-Chong; Park, Mi-Hyun; Kim, Hwa-Young; Kwon, Byoung-Mog; Baek, Nam-In

    2006-11-01

    Ixeris dentata forma albiflora was extracted with 80% aqueous MeOH, and the concentrated extract was partitioned with EtOAc, n-BuOH and H2O. Eight sesquiterpenes were isolated through repeated silica gel and octadecyl silica gel (C18, ODS) column chromatography of the EtOAc and n-BuOH fractions. Physicochemical analysis using NMR, MS and IR revealed the chemical structures of the sesquiterpenes, which were zaluzanin (1), 9a-hydroxyguaian-4(15),10(14),11(13)-triene-6,12-olide (2), 3beta-O-beta-D-glucopyranosyl-8beta-hydroxyguaian-4(15),10(14)-diene-6,12-olide (3), 3-O-beta-D-glucopyranosyl-8beta-hydroxyguauan-10(14)-ene-6,12-olide (4), ixerin M (5), glucozaluzanin C (6), crepiside I (7), and ixerin D (8). This is the first time that these sesquiterpene lactones have been isolated from this plant. Compounds 1, 2 and 7 revealed relatively high cytotoxicities on human colon carcinoma cell and lung adenocarcinoma cell, while compounds 5 and 7 showed acyl-CoA: cholesterol acyltransferase (ACAT) inhibitory activity.

  6. Endoplasmic reticulum targeting in Ewing's sarcoma by the alkylphospholipid analog edelfosine

    PubMed Central

    Bonilla, Ximena; Dakir, EL-Habib; Mollinedo, Faustino; Gajate, Consuelo

    2015-01-01

    Ewing's sarcoma (ES) is the second most common bone cancer in children and young people. Edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) is the prototype of a family of synthetic antitumor compounds, collectively known as alkylphospholipid analogs (APLs). We have found that APLs ranked edelfosine>perifosine>erucylphosphocholine>miltefosine for their capacity to promote apoptosis in ES cells. Edelfosine accumulated in the endoplasmic reticulum (ER) and triggered an ER stress response that eventually led to caspase-dependent apoptosis in ES cells. This apoptotic response involved mitochondrial-mediated processes, with cytochrome c release, caspase-9 activation and generation of reactive oxygen species. Edelfosine-induced apoptosis was also dependent on sustained c-Jun NH2-terminal kinase activation. Oral administration of edelfosine showed a potent in vivo antitumor activity in an ES xenograft animal model. Histochemical staining gave evidence for ER stress response and apoptosis in the ES tumors isolated from edelfosine-treated mice. Edelfosine showed a preferential action on ES tumor cells as compared to non-transformed osteoblasts, and appeared to be well suited for combination therapy regimens. These results demonstrate in vitro and in vivo antitumor activity of edelfosine against ES cells that is mediated by caspase activation and ER stress, and provide the proof of concept for a putative edelfosine- and ER stress-mediated approach forES treatment. PMID:25999349

  7. Mixed-mode sorption of hydroxylated atrazine degradation products to sell: A mechanism for bound residue

    USGS Publications Warehouse

    Lerch, R.N.; Thurman, E.M.; Kruger, E.L.

    1997-01-01

    This study tested the hypothesis that sorption of hydroxylated atrazine degradation products (HADPs: hydroxyatrazine, HA; deethylhydroxyatrazine, DEHA; and deisopropylhydroxyatrazine, DIHA) to soils occurs by mixed-mode binding resulting from two simultaneous mechanisms: (1) cation exchange and (2) hydrophobic interaction. The objective was to use liquid chromatography and soil extraction experiments to show that mixed-mode binding is the mechanism controlling HADP sorption to soils and is also a mechanism for bound residue. Overall, HADP binding to solid-phase extraction (SPE) sorbents occurred in the order: cation exchange >> octadecyl (C18) >> cyanopropyl. Binding to cation exchange SPE and to a high-performance liquid chromatograph octyl (C8) column showed evidence for mixed-mode binding. Comparison of soil extracted by 0.5 M KH2P04, pH 7.5, or 25% aqueous CH3CN showed that, for HA and DIHA, cation exchange was a more important binding mechanism to soils than hydrophobic interaction. Based on differences between several extractants, the extent of HADP mixed-mode binding to soil occurred in the following order: HA > DIHA > DEHA. Mixed-mode extraction recovered 42.8% of bound atrazine residues from aged soil, and 88% of this fraction was identified as HADPs. Thus, a significant portion of bound atrazine residues in soils is sorbed by the mixed-mode binding mechanisms.

  8. Control of heterogeneous nucleation and growth kinetics of dopamine-melanin by altering substrate chemistry.

    PubMed

    Klosterman, Luke; Riley, John K; Bettinger, Christopher John

    2015-03-24

    Dopamine-melanin (DM or "polydopamine") can be deposited on virtually any substrate from solution through autoxidation of dopamine. The versatility of this process has allowed surface-mediated assembly of DM for a wide variety of functional coatings. Here we report the impact of well-defined surface chemistries on the nucleation and growth of such films. DM was deposited on silicon dioxide (SiO2) and SiO2 substrates modified with self-assembled monolayers (SAMs) bearing octadecyl (C18), phenethyl, and aminopropyl functional groups. Atomic force microscopy revealed three-dimensional islands whose areal density and surface coverage are lowest on bare SiO2 substrates and highest on the neutral aromatic and aliphatic substrates. Increasing the pH of the solution from 8.2 to 10 dissociates catechol moieties in DM and inhibits adsorption on negatively charged SiO2 substrates. The growth rate of DM films on SAM-modified SiO2 is maximized at pH 9.5 and almost completely abolished at pH 10 because of increased DM solubility. The initial rates of DM adsorption were measured using quartz crystal microbalance with dissipation measurements. The initial adsorption rate is proportional to the nucleation density, which increases as the hydrophobicity of the substrate increases. Taken together, these data provide insight into the rates of heterogeneous nucleation and growth of DM on substrates with well-defined chemistries.

  9. Tween surfactants: Adsorption, self-organization, and protein resistance

    NASA Astrophysics Data System (ADS)

    Shen, Lei; Guo, Athena; Zhu, Xiaoyang

    2011-03-01

    Tween surfactants, each containing hydrophilic ethylene glycol head groups and a hydrophobic alkyl tail, are being actively explored as protein-resistant surface coatings, but little is known about how they adsorb on surfaces. We carry out a comparative study of the adsorption of two Tween molecules (same hydrophilic head group, but a shorter dodecyl tail for Tween 20 and a longer octadecyl tail for Tween 40) on Au and polystyrene surfaces. Despite the similarity between these two molecules, there is a drastic difference in their protein resistance: a monolayer of Tween 20 on a hydrophobic surface is repulsive against protein adsorption but that of Tween 40 is not. The difference in protein resistance can be attributed to two distinctly different adsorption mechanisms. While the adsorption of Tween 40 is described by a simple first-order mechanism, that of Tween 20 consists of a fast adsorption step and a slower reorganization process at a high surface coverage. The latter leads to the formation of a high-density and self-organized monolayer, which is responsible for the enhanced stability and resistance against non-specific protein adsorption.

  10. Asphaltene Adsorption onto Self-Assembled Monolayers of Mixed Aromatic

    SciTech Connect

    Turgman-Cohen, S.; Smith, M; Fischer, D; Kilpatrick, P; Genzer, J

    2009-01-01

    The adsorption of asphaltenes onto flat solid surfaces modified with mixed self-assembled monolayers (SAMs) of aliphatic and aromatic trichlorosilanes with varying wettabilities, aromaticities, and thicknesses is tested. The mixed SAMs are characterized by means of contact angle to assess hydrophobicity and molecular and chemical uniformity, spectroscopic ellipsometry to measure the thickness of the films, and near edge X-ray absorption fine structure (NEXAFS) spectroscopy to assess chemical and molecular composition. The molecular characteristics of the adsorbed asphaltene layer and the extent of asphaltene adsorption are determined using NEXAFS and spectroscopic ellipsometry, respectively. The SAMs are formed by depositing phenyl-, phenethyl-, butyl-, and octadecyl- trichlorosilanes from toluene solutions onto silica-coated substrates; the chemical composition and the wettability of the SAM surface is tuned systematically by varying the trichlorosilane composition in the deposition solutions. The adsorption of asphaltenes on the substrates does not correlate strongly with the SAM chemical composition. Instead, the extent of asphaltene adsorption decreases with increasing SAM thickness. This observation suggests that the leading interaction governing the adsorption of asphaltenes is their interaction with the polar silica substrate and that the chemical composition of the SAM is of secondary importance.

  11. Molecular structure of an alkyl-side-chain polymer-water interface: origins of contact angle hysteresis.

    PubMed

    Rangwalla, Hasnain; Schwab, Alexander D; Yurdumakan, Betül; Yablon, Dalia G; Yeganeh, Mohsen S; Dhinojwala, Ali

    2004-09-28

    A new and direct approach to verify surface heterogeneity as the microscopic origin of contact-angle hysteresis is demonstrated. IR-visible sum-frequency-generation spectroscopy (SFG) was used to selectively probe the molecules at the interface of an alkyl-side-chain polymer [poly(vinyl n-octadecyl carbamate-co-vinyl acetate)] with water. The spectra indicate that in contact with water, the polymer surface is heterogeneous (having areas of differing surface energies). This evidence of surface heterogeneity supports the hysteresis observed in the advancing and receding contact angles of the polymer surface with water. The same measurements made for the chemically and structurally similar surface of an octadecyltrichlorosilane self-assembled monolayer indicates a homogeneous surface at the water interface. In this case, contact-angle hysteresis measurements implicate surface roughness as the cause of hysteresis. Atomic force microscopy measurements of roughness for these surfaces further support our conclusions. The polymer-water interface was probed using SFG at above-ambient temperatures, and an order-to-disorder transition (ODT) of alkyl side chains at the interface was observed, which closely follows the melting of crystalline side chains in the bulk. This transition explains the increased wettability of the polymer, by water, when the temperature is raised above the bulk melting temperature. Furthermore, the irreversibility of this ODT suggests that the disordered polymer-water interface is the thermodynamic equilibrium state, whereas the before-heating structure of this interface is a kinetically hindered metastable state.

  12. Development and Validation of Reversed-Phase High Performance Liquid Chromatographic Method for Hydroxychloroquine Sulphate.

    PubMed

    Singh, A; Roopkishora; Singh, C L; Gupta, R; Kumar, S; Kumar, M

    2015-01-01

    In the present work new, simple reversed-phase high performance liquid chromatographic method was developed and validated for the determination of hydroxychloroquine sulphate in blood plasma. Chloroquine sulphate was used as an internal standard. The chromatographic separation was achieved with octadecyl silane Hypersil C18 column (250×6 mm, 5 μm) using water and organic (acetonitrile:methanol: 50:50, v/v) mobile phase in 75:25 v/v ratio, with sodium 1-pentanesulfonate and phosphoric acid. This organic phase was maintained at pH 3.0 by orthophosphoric acid. The flow rate of 2.0 ml/min(.) with detection at 343 nm was used in the analysis. The calibration curve of standard hydroxychloroquine sulphate was linear in range 0.1-20.0 μg/ml. The method was validated with respected to linearity, range, precision, accuracy, specificity and robustness studies according to ICH guidelines. The method was found to be accurate and robust to analyze the hydroxychloroquine sulphate in plasma samples.

  13. Effect of the precise branching of polyethylene at each 21st CH2 group on its phase transitions, crystal structure, and morphology

    SciTech Connect

    Qui, Wulin; Sworen, John; Pyda, Marek {nmn}; Nowak-Pyda, Elisabieta; Habenschuss, Anton {Tony}; Wagener, Kenneth; Wunderlich, Bernhard {nmn}

    2006-01-01

    Three linear polyethylenes with branches at every 21st backbone atom have been analyzed by differential scanning calorimetry (DSC) and quasi-isothermal, temperature-modulated DSC. The branches were methyl (PE1M), dimethyl (PE2M), and ethyl groups (PE1E). Linear polyethylene (HDPE) and atactic poly(octadecyl acrylate) (PODA) were also analyzed. All were compared to a random poly(ethylene-co-octene-1) of similar branch concentration (LLDPE) and poly(4,4'-phthaloimidobenzoyldoeicosyleneoxycarbonyl) (PEIM-22). The HDPE has the highest melting temperature and crystallinity with relatively large contributions of reversing melting when grown as folded-chain crystals. The precisely branched polyethylenes and copolymers have lower melting temperatures and heats of fusion. Of the branched samples, PE1M crystallizes more readily, followed by PE1E and PE2M, with PE2M showing cold crystallization. In contrast to paraffins of equal length which melt fully reversibly, the precisely designed, branched polymers melt largely irreversibly with small amounts of reversing melting, which is least for the best-grown crystals. The PE1M forms monoclinic, PE1E, pseudohexagonal, or triclinic crystals, and PE2M has a multitude of crystal structures.

  14. A simple method for the synthesis of a polar-embedded and polar-endcapped reversed-phase chromatographic packing with low activity of residue silanols.

    PubMed

    Liu, Hai-yan; Li, Zhi-yong; Liu, Dan; Xue, Ying-wen; Shi, Zhi-guo

    2016-04-22

    Octadecyl bonded silica (ODS) is the most popular packing for reversed-phase chromatography. However, it generally demonstrates bad resolution for polar analytes because of the residue silanols and its poor stability in aqueous mobile phase. To address the problem, a new reversed-phase packing containing both polar-embedded and polar-endcapped moieties was proposed. It was prepared by a very simple method, in which the epoxide addition reaction of 3-glycidoxypropyltrimethoxysilane with 1-octadecanethiol proceeded simultaneously with the reaction of silane coupling onto silica particles. By controlling the molecular ratio of 3-glycidoxypropyltrimethoxysilane to 1-octadecanethiol higher than 1.0 (1.56 for the present study), both polar-embedded and polar-endcapped moieties were achieved onto the packing. The performance of the packing was evaluated in detail. The results demonstrated that neutral, acidic and basic analytes were well separated on the packing. The column efficiency for phenanthrene was 34,200 theoretical plates per meter. In addition, four nucleotides can be separated in 100% phosphate buffered saline solution with good reproducibility, which indicates the packing has good stability in aqueous mobile phase. Amitriptyline, a typical basic analytes, was eluted out with relatively symmetric peak shape (asymmetry factor of 1.36), which implies that the packing has not suffered from the negative effect of residue silanols significantly. Good stability in buffer solution of pH ranging from 2.0 to 10.0 was also documented for the packing.

  15. Determination of delta 1-tetrahydrocannabinol in human fat biopsies from marihuana users by gas chromatography-mass spectrometry.

    PubMed

    Johansson, E; Norén, K; Sjövall, J; Halldin, M M

    1989-01-01

    A gas chromatographic-mass spectrometric (GC/MS) method for analysis of delta 1-tetrahydrocannabinol (delta 1-THC) in human fat samples is described. The fat sample, obtained from heavy marihuana users 1 week before and 4 weeks after smoking, is homogenized in hexane + 2-propanol, centrifuged, and the supernatant mixed with Lipidex 5000. The solvent is evaporated and the dried gel is packed in a glass column. delta 1-THC is eluted from the column with methanol + water + acetic acid, diluted with water and the eluent is passed through a bed of Octadecylsilane-bonded silica. After washing and drying, the retained delta 1-THC is eluted with hexane, derivatized with N-methyl-N-(t-butyl-dimethysilyl)trifluoroacetamide (MTBSTFA) and finally purified by HPLC on an Octadecyl Sl 100 column in methanol. The amount of delta 1-THC is determined by GC/MS, using selected ion monitoring, and a deuterated internal standard. The recovery of delta 1-THC is about 80%, and the concentration of delta 1-THC in the fat samples analysed ranged between 0.4 and 193 ng/g wet tissue.

  16. Surface modification of polyethylene film by acrylamide graft and alcoholysis for improvement of antithrombogenicity

    NASA Astrophysics Data System (ADS)

    Zhao, Guowei; Chen, Yashao; Wang, Xiaoli

    2007-03-01

    To improve antithrombogenicity of polyethylene (PE) films, the films pretreated by Ar plasma were radiated by ultraviolet light to initiate grafting polymerization with acrylamide (AAm) in absence of photo-initiator, then the AAm-grafted PE films (PE-g-AAm) were alcoholized with octadecyl alcohol. Effects of Ar plasma composite parameter ( W/ FM), pretreated time, AAm monomer concentration, and UV irradiation time on grafting rate were investigated systematically. AAm-grafted PE film and alcoholized PE film (PE-g-SAAm) were characterized by contact angle, X-ray photoelectron spectroscopy (XPS), attenuated total reflectance Fourier transfer infrared (ATR-FT-IR) spectroscopy and atomic force microscope (AFM), respectively. The results indicated that the moieties of AAm and stearyl were successively immobilized onto the PE surface. The platelet adhesion experiment showed that antithrombogenicity of the modified PE films was improved in comparison with PE films. The change in antithrombogenicity is attributed to the surface of the modified film in presence of tail-like structure which consists of polyacrylamide as spacer and stearyl as end groups.

  17. Determination of competitive adsorption isotherms applying the nonlinear frequency response method. Part II. Experimental demonstration.

    PubMed

    Ilić, Milica; Petkovska, Menka; Seidel-Morgenstern, Andreas

    2009-08-14

    This paper demonstrates an experimental application of the nonlinear frequency response (FR) method extension to determine adsorption isotherms of binary mixtures. This method, based on the analysis of the response of a chromatographic column subjected to the sinusoidal inlet concentration changes, is shown to be an alternative for isotherm determination. The critical issue related to the successful application of the method is to reach experimentally the low frequency asymptotic behaviour of the corresponding frequency response functions (FRFs). Although, there are different possibilities to perform periodical inlet concentration changes, in this paper only simultaneous changes for both components were considered. The adsorption of phenol and 2-phenylethanol on octadecyl silica was analyzed experimentally using a mixture of methanol and water as a solvent. Parameters of competitive isotherms were also estimated for comparison using the classical perturbation method. Despite certain differences between competitive isotherms estimated with the two methods that were found, the obtained results show the potential of the nonlinear FR method for measuring competitive isotherms.

  18. Optimization of matrix solid-phase dispersion for the rapid determination of salicylate and benzophenone-type UV absorbing substances in marketed fish.

    PubMed

    Tsai, Dung-Ying; Chen, Chien-Liang; Ding, Wang-Hsien

    2014-07-01

    A simple and effective method for the rapid determination of five salicylate and benzophenone-type UV absorbing substances in marketed fish is described. The method involves the use of matrix solid-phase dispersion (MSPD) prior to their determination by on-line silylation gas chromatography tandem mass spectrometry (GC-MS/MS). The parameters that affect the extraction efficiency were optimized using a Box-Behnken design method. The optimal extraction conditions involved dispersing 0.5g of freeze-dried powdered fish with 1.0g of Florisil using a mortar and pestle. This blend was then transferred to a solid-phase extraction (SPE) cartridge containing 1.0g of octadecyl bonded silica (C18), as the clean-up co-sorbent. The target analytes were then eluted with 7mL of acetonitrile. The extract was derivatized on-line in the GC injection-port by reaction with a trimethylsilylating (TMS) reagent. The TMS-derivatives were then identified and quantitated by GC-MS/MS. The limits of quantitation (LOQs) were less than 0.1ng/g.

  19. Thermal diffusion behavior of hard-sphere suspensions

    NASA Astrophysics Data System (ADS)

    Ning, Hui; Buitenhuis, Johan; Dhont, Jan K. G.; Wiegand, Simone

    2006-11-01

    We studied the thermal diffusion behavior of octadecyl coated silica particles (Rh=27nm) in toluene between 15.0 and 50.0°C in a volume fraction range of 1%-30% by means of thermal diffusion forced Rayleigh scattering. The colloidal particles behave like hard spheres at high temperatures and as sticky spheres at low temperatures. With increasing temperature, the obtained Soret coefficient ST of the silica particles changed sign from negative to positive, which implies that the colloidal particles move to the warm side at low temperatures, whereas they move to the cold side at high temperatures. Additionally, we observed also a sign change of the Soret coefficient from positive to negative with increasing volume fraction. This is the first colloidal system for which a sign change with temperature and volume fraction has been observed. The concentration dependence of the thermal diffusion coefficient of the colloidal spheres is related to the colloid-colloid interactions, and will be compared with an existing theoretical description for interacting spherical particles. To characterize the particle-particle interaction parameters, we performed static and dynamic light scattering experiments. The temperature dependence of the thermal diffusion coefficient is predominantly determined by single colloidal particle properties, which are related to colloid-solvent molecule interactions.

  20. Asphaltene adsorption onto self-assembled monolayers of mixed aromatic and aliphatic trichlorosilanes.

    PubMed

    Turgman-Cohen, Salomon; Smith, Matthew B; Fischer, Daniel A; Kilpatrick, Peter K; Genzer, Jan

    2009-06-02

    The adsorption of asphaltenes onto flat solid surfaces modified with mixed self-assembled monolayers (SAMs) of aliphatic and aromatic trichlorosilanes with varying wettabilities, aromaticities, and thicknesses is tested. The mixed SAMs are characterized by means of contact angle to assess hydrophobicity and molecular and chemical uniformity, spectroscopic ellipsometry to measure the thickness of the films, and near edge X-ray absorption fine structure (NEXAFS) spectroscopy to assess chemical and molecular composition. The molecular characteristics of the adsorbed asphaltene layer and the extent of asphaltene adsorption are determined using NEXAFS and spectroscopic ellipsometry, respectively. The SAMs are formed by depositing phenyl-, phenethyl-, butyl-, and octadecyl- trichlorosilanes from toluene solutions onto silica-coated substrates; the chemical composition and the wettability of the SAM surface is tuned systematically by varying the trichlorosilane composition in the deposition solutions. The adsorption of asphaltenes on the substrates does not correlate strongly with the SAM chemical composition. Instead, the extent of asphaltene adsorption decreases with increasing SAM thickness. This observation suggests that the leading interaction governing the adsorption of asphaltenes is their interaction with the polar silica substrate and that the chemical composition of the SAM is of secondary importance.

  1. Determination of the hop-derived phytoestrogen, 8-prenylnaringenin, in beer by gas chromatography/mass spectrometry.

    PubMed

    Tekel', J; De Keukeleire, D; Rong, H; Daeseleire, E; Van Peteghem, C

    1999-12-01

    A method was developed to determine 8-prenylnaringenin, a novel hop-derived phytoestrogen, in beer. Matrix purification involved solid-phase extraction on octadecyl silica followed by liquid/liquid extraction on a ChemElut 1010 column connected to a Florisil adsorption/desorption cartridge. 8-Prenylnaringenin was eluted from the tandem columns using a 1:1 mixture of diethyl ether and ethyl acetate and subsequently determined as tris(trimethylsilyl) ether by GC/MS-SIM. The recovery of 8-prenylnaringenin in beer samples was between 61.1 +/- 6.6 and 82.2 +/- 8.8% for levels of 37 and 92.5 microg L(-1), respectively, and the detection limit was approximately 5 microg L(-1). Although most beers do not contain 8-prenylnaringenin in detectable quantities, the highest concentration found was 19.8 microg L(-1). The concentration of 8-prenylnaringenin in beers and, possibly, its absence depend on the selection of particular hop varieties, the hopping rate, or the type of hop product used in brewing. The efficiency of transfer of 8-prenylnaringenin from hops to beer is between 10 and 20%.

  2. Synthesis of Non-Toxic Silica Particles Stabilized by Molecular Complex Oleic-Acid/Sodium Oleate

    PubMed Central

    Spataru, Catalin Ilie; Ianchis, Raluca; Petcu, Cristian; Nistor, Cristina Lavinia; Purcar, Violeta; Trica, Bogdan; Nitu, Sabina Georgiana; Somoghi, Raluca; Alexandrescu, Elvira; Oancea, Florin; Donescu, Dan

    2016-01-01

    The present work is focused on the preparation of biocompatible silica particles from sodium silicate, stabilized by a vesicular system containing oleic acid (OLA) and its alkaline salt (OLANa). Silica nanoparticles were generated by the partial neutralization of oleic acid (OLA), with the sodium cation present in the aqueous solutions of sodium silicate. At the molar ratio OLA/Na+ = 2:1, the molar ratio (OLA/OLANa = 1:1) required to form vesicles, in which the carboxyl and carboxylate groups have equal concentrations, was achieved. In order to obtain hydrophobically modified silica particles, octadecyltriethoxysilane (ODTES) was added in a sodium silicate sol–gel mixture at different molar ratios. The interactions between the octadecyl groups from the modified silica and the oleyl chains from the OLA/OLANa stabilizing system were investigated via simultaneous thermogravimetry (TG) and differential scanning calorimetry (DSC) (TG-DSC) analyses.A significant decrease in vaporization enthalpy and an increase in amount of ODTES were observed. Additionally, that the hydrophobic interaction between OLA and ODTES has a strong impact on the hybrids’ final morphology and on their textural characteristics was revealed. The highest hydrodynamic average diameter and the most negative ζ potential were recorded for the hybrid in which the ODTES/sodium silicate molar ratio was 1:5. The obtained mesoporous silica particles, stabilized by the OLA/OLANa vesicular system, may find application as carriers for hydrophobic bioactive molecules. PMID:27869768

  3. Solid-phase extraction-gas chromatography and solid-phase extraction-gas chromatography-mass spectrometry determination of corrosion inhibiting long-chain primary alkyl amines in chemical treatment of boiler water in water-steam systems of power plants.

    PubMed

    Kusch, Peter; Knupp, Gerd; Hergarten, Marcus; Kozupa, Marian; Majchrzak, Maria

    2006-04-28

    Gas chromatography with simultaneous flame-ionization detection (FID) and a nitrogen-phosphorus detection (NPD) as well as gas chromatography-mass spectrometry (GC/MS) has been used to characterize long-chain primary alkyl amines after derivatization with trifluoroacetic anhydride (TFAA). Electron impact ionization- (EI) and negative chemical ionization (NCI) mass spectra of trifluoroacetylated derivatives of the identified tert-octadecylamines are presented for the first time. The corrosion inhibiting alkyl amines were applied in a water-steam circuit of energy systems in the power industry. Solid-phase extraction (SPE) with octadecyl bonded silica (C18) sorbents followed by gas chromatography were used for quantification of the investigated tert-octadecylamines in boiler water, superheated steam and condensate samples from the power plant. The estimated values were: 89 microg l(-1)(n = 5, RSD = 7.8%), 45 microg l(-1) (n = 5, RSD = 5.4%) and 37 microg l(-1)(n = 5, RSD = 2.3%), respectively.

  4. In vitro angiotensin I converting enzyme inhibition by a peptide isolated from Chiropsalmus quadrigatus Haeckel (box jellyfish) venom hydrolysate.

    PubMed

    So, Pamela Berilyn T; Rubio, Peter; Lirio, Stephen; Macabeo, Allan Patrick; Huang, Hsi-Ya; Corpuz, Mary Jho-Anne T; Villaflores, Oliver B

    2016-09-01

    The anti-angiotensin I converting enzyme activity of box jellyfish, Chiropsalmus quadrigatus Haeckel venom hydrolysate was studied. The venom extract was obtained by centrifugation and ultrasonication. Protein concentration of 12.99 μg/mL was determined using Bradford assay. The pepsin and papain hydrolysate was tested for its toxicity by Limit test following the OECD Guideline 425 using 5 female Sprague-Dawley rats. Results showed that the hydrolysate is nontoxic with an LD50 above 2000 mg/kg. In vitro angiotensin I converting enzyme (ACE) inhibitory activity was determined using ACE kit-WST. Isolation of ACE inhibitory peptides using column chromatography with SP-Sephadex G-25 yielded 8 pooled fractions with fraction 3 (86.5%) exhibiting the highest activity. This was followed by reverse phase - high performance liquid chromatography (RP-HPLC) with an octadecyl silica column (Inertsil ODS-3) using methanol:water 15:85 at a flow rate of 1.0 mL/min. Among the 13 fractions separated with the RP-HPLC, fraction 3.5 exhibited the highest ACE inhibitory activity (84.1%). The peptide sequence ACPGPNPGRP (IC50 2.03 μM) from fraction 3.5 was identified using Matrix-assisted laser desorption/ionization with time-of-flight tandem mass spectroscopy analysis (MALDI-TOF/MS).

  5. Reduction of water surface tension significantly impacts gecko adhesion underwater.

    PubMed

    Stark, Alyssa Y; McClung, Brandon; Niewiarowski, Peter H; Dhinojwala, Ali

    2014-12-01

    The gecko adhesive system is dependent on weak van der Waals interactions that are multiplied across thousands of fine hair-like structures (setae) on geckos' toe pads. Due to the requirements of van der Waals forces, we expect that any interruption between the setae and substrate, such as a water layer, will compromise adhesion. Our recent results suggest, however, that the air layer (plastron) surrounding the superhydrophobic toe pads aid in expelling water at the contact interface and create strong shear adhesion in water when in contact with hydrophobic surfaces. To test the function of the air plastron, we reduced the surface tension of water using two surfactants, a charged anionic surfactant and a neutral nonionic surfactant. We tested geckos on three substrates: hydrophilic glass and two hydrophobic surfaces, glass with a octadecyl trichlorosilane self-assembled monolayer (OTS-SAM) and polytetrafluoroethylene (PTFE). We found that the anionic surfactant inhibited the formation of the air plastron layer and significantly reduced shear adhesion to all three substrates. Interestingly, the air plastron was more stable in the nonionic surfactant treatments than the anionic surfactant treatments and we found that geckos adhered better in the nonionic surfactant than in the anionic surfactant on OTS-SAM and PTFE but not on glass. Our results have implications for the evolution of a superhydrophobic toe pad and highlight some of the challenges faced in designing synthetic adhesives that mimic geckos' toes.

  6. Methods of analysis by the U. S. Geological Survey National Water Quality Laboratory - determination of organonitrogen herbicides in water by solid-phase extraction and capillary-column gas chromatography/mass spectrometry with selected-ion monitoring

    USGS Publications Warehouse

    Sandstrom, Mark W.; Wydoski, Duane S.; Schroeder, Michael P.; Zamboni, Jana L.; Foreman, William T.

    1992-01-01

    A method for the isolation of organonitrogen herbicides from natural water samples using solid-phase extraction and analysis by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring is described. Water samples are filtered to remove suspended particulate matter and then are pumped through disposable solid-phase extraction cartridges containing octadecyl-bonded porous silica to remove the herbicides. The cartridges are dried using carbon dioxide, and adsorbed herbicides are removed from the cartridges by elution with 1.8 milliliters of hexaneisopropanol (3:1). Extracts of the eluants are analyzed by capillary-column gas chromatography/mass spectrometry with selected-ion monitoring of at least three characteristic ions. The method detection limits are dependent on sample matrix and each particular herbicide. The method detection limits, based on a 100-milliliter sample size, range from 0.02 to 0.25 microgram per liter. Recoveries averaged 80 to 115 percent for the 23 herbicides and 2 metabolites in 1 reagent-water and 2 natural-water samples fortified at levels of 0.2 and 2.0 micrograms per liter.

  7. Sensitivity enhancement for the analysis of naproxen in tap water by solid-phase extraction coupled in-line to capillary electrophoresis.

    PubMed

    Macià, Alba; Borrull, Francesc; Calull, Marta; Benavente, Fernando; Hernández, Elena; Sanz-Nebot, Victòria; Barbosa, José; Aguilar, Carme

    2008-03-01

    SPE coupled in-line to CE, as the strategy to enhance the concentration sensitivity in CE, has been used to enrich naproxen in tap water samples. In this study, a microcartridge containing an octadecyl silica (C18) sorbent was placed near the inlet within the separation capillary column. The optimum conditions were obtained when naproxen in an acidic aqueous solution (pH 3.5) was loaded into the capillary at 930 mbar for 30 min, and 20 mM ammonium acetate in methanol/water (70:30 v/v) was used as both an elution solution and a separation BGE. Under these conditions, the sensitivity was enhanced 1820-fold with respect to normal hydrodynamic injection, and the LOD achieved was 0.2 microg/L. To show the capability of the in-line SPE-CE method, tap water samples were analysed after a pretreatment consisting in an off-line C18-SPE procedure. The recovery of this procedure was higher than 80%. Under these conditions, naproxen could be detected at a concentration of 10 ng/L; so the potential of the procedure for the sensitive analysis of this type of drugs in water samples was demonstrated. Afterwards, these results were compared with those previously obtained for naproxen in water samples using different sample stacking techniques.

  8. Self-assembled monolayer-functionalized half-metallic manganite for molecular spintronics.

    PubMed

    Tatay, Sergio; Barraud, Clément; Galbiati, Marta; Seneor, Pierre; Mattana, Richard; Bouzehouane, Karim; Deranlot, Cyrile; Jacquet, Eric; Forment-Aliaga, Alicia; Jegou, Pascale; Fert, Albert; Petroff, Frédéric

    2012-10-23

    (La,Sr)MnO(3) manganite (LSMO) has emerged as the standard ferromagnetic electrode in organic spintronic devices due to its highly spin-polarized character and air stability. Whereas organic semiconductors and polymers have been mainly envisaged to propagate spin information, self-assembled monolayers (SAMs) have been overlooked and should be considered as promising materials for molecular engineering of spintronic devices. Surprisingly, up to now the first key step of SAM grafting protocols over LSMO surface thin films is still missing. We report the grafting of dodecyl (C12P) and octadecyl (C18P) phosphonic acids over the LSMO half-metallic oxide. Alkylphosphonic acids form ordered self-assembled monolayers, with the phosphonic group coordinated to the surface and alkyl chains tilted from the surface vertical by 43° (C12P) and 27° (C18P). We have electrically characterized these SAMs in nanodevices and found that they act as tunnel barriers, opening the door toward the integration of alkylphosphonic acid//LSMO SAMs into future molecular/organic spintronic devices such as spin OLEDs.

  9. [Determination of illudin S in Omphalotus guepiniformis and foods that caused food poisoning by liquid chromatography with tandem mass spectrometry].

    PubMed

    Kasahara, Yoshimasa; Itou, Takeshi

    2009-08-01

    A simple method was developed for determination of illudin S in fungi (Omphalotus guepiniformis: poisonous mushroom) and a food that caused food poisoning, using liquid chromatography tandem mass spectrometry (LC/MS/MS). Illudin S in fungi and the food that caused food poisoning was extracted with methanol and then cleaned up with an Oasis HLB cartridge. LC separation was performed with an octadecylated silica column (Inertsil ODS-3, 2.1 mm i.d. x 150 mm) and a mobile phase of 0.1% formic acid-methanol (7 : 3) at a flow rate 0.2 mL/min. Mass spectral acquisition was performed in the positive mode and illudin S was targeted using multiple reaction monitoring (MRM) with electrospray ionization (ESI). The recoveries of illudin S were 84-94% from edible fungi (Lentinula edodes, Pleurotus ostreatus and Panellus serotinus). The detection limits of illudin S in the fungi (L. edodes, P. ostreatus and P. serotinus) were 0.08-0.10 microg/g respectively. Illudin S was detected in the food that caused food poisoning at the level of 2.0 and 15.1 microg/g in the soup and fungi, respectively. The recovery of illudin S from a mushroom soup (cooked at 100 degrees C for 10 min) sample which simulated food poisoning was 74.8%. These results indicate that the developed method is suitable for the determination of illudin S in fungi (O. guepiniformis) and foods that caused food poisoning.

  10. Involvement of lipid rafts in the localization and dysfunction effect of the antitumor ether phospholipid edelfosine in mitochondria

    PubMed Central

    Mollinedo, F; Fernández, M; Hornillos, V; Delgado, J; Amat-Guerri, F; Acuña, A U; Nieto-Miguel, T; Villa-Pulgarín, J A; González-García, C; Ceña, V; Gajate, C

    2011-01-01

    Lipid rafts and mitochondria are promising targets in cancer therapy. The synthetic antitumor alkyl-lysophospholipid analog edelfosine (1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine) has been reported to target lipid rafts. Here, we have found that edelfosine induced loss of mitochondrial membrane potential and apoptosis in human cervical carcinoma HeLa cells, both responses being abrogated by Bcl-xL overexpression. We synthesized a number of new fluorescent edelfosine analogs, which preserved the proapoptotic activity of the parent drug, and colocalized with mitochondria in HeLa cells. Edelfosine induced swelling in isolated mitochondria, indicating an increase in mitochondrial membrane permeability. This mitochondrial swelling was independent of reactive oxygen species generation. A structurally related inactive analog was unable to promote mitochondrial swelling, highlighting the importance of edelfosine molecular structure in its effect on mitochondria. Raft disruption inhibited mitochondrial localization of the drug in cells and edelfosine-induced swelling in isolated mitochondria. Edelfosine promoted a redistribution of lipid rafts from the plasma membrane to mitochondria, suggesting a raft-mediated link between plasma membrane and mitochondria. Our data suggest that direct interaction of edelfosine with mitochondria eventually leads to mitochondrial dysfunction and apoptosis. These observations unveil a new framework in cancer chemotherapy that involves a link between lipid rafts and mitochondria in the mechanism of action of an antitumor drug, thus opening new avenues for cancer treatment. PMID:21593790

  11. Investigation of the interactions of lupane type pentacyclic triterpenes with outer leaflet membrane phospholipids--Langmuir monolayer and synchrotron X-ray scattering study.

    PubMed

    Broniatowski, Marcin; Flasiński, Michał; Wydro, Paweł

    2012-09-01

    Lupane type pentacyclic triterpenes (LTs) are pharmacologically active natural products isolated from different plants. They have broad spectrum of therapeutic action ranging from anticancer via anti-HIV, antibiotic to anti-inflammatory and anti-protozoal activity. Many scientific papers underline that the key stage in the LT mechanism of action is their incorporation into cellular membrane and the interaction with the structural lipids. In our research we apply Langmuir monolayers as a versatile platform for the investigation of these phenomena, since till now important aspects concerning this issue are incomprehensible. We focus our attention on the interactions of lupeol and betulinic acid with choline-headgroup structural lipids: a representative of saturated glycerophosphatidylcholines (DPPCs), and octadecyl-sphingomyelin--a representative of membrane sphingolipids. Application of complementary physicochemical techniques such as the Langmuir technique, Brewster angle microscopy, and grazing incidence X-ray diffraction supported by thermodynamic analysis enabled us to investigate the intermolecular interactions in such binary model systems. Our results corroborate that LT is miscible with the outer leaflet membrane phospholipids, both DPPC and SM in the whole range of mole ratios. Moreover, the introduction of LT into the phospholipid film, even in small proportion, leads to the loss of periodical ordering of the phospholipid molecules and the disappearance of the diffraction signal as observed by GIXD. Our results also proved that LT does not form any surface complexes of fixed stoichiometry resembling the well characterized lipid rafts.

  12. Characterisation of RPLC columns packed with porous sub-2 microm particles.

    PubMed

    Petersson, Patrik; Euerby, Melvin R

    2007-08-01

    Eight commercially available sub-2 microm octadecyl silane columns (C18 columns) have been characterised by the Tanaka protocol. The columns can be grouped into two groups that display large differences in selectivity and peak shape due to differences in hydrophobicity, degree of surface coverage and silanol activity. Measurements of particle size distributions were made using automated microscopy and electrical sensing zone measurements. Only a weak correlation could be found between efficiency and particle size. Large differences in column backpressure were observed. These differences are not related to particle size distribution. A more likely explanation is differences in packing density. In order to take full advantage of 100-150 mm columns packed with sub-2 microm particles, it is often necessary to employ not only an elevated pressure but also an elevated temperature. A comparison between columns packed with sub-2, 3 and 5 microm versions of the same packing indicates potential method transferability problems for several of the columns due to selectivity differences. Currently, the best alternative for fast high-resolution LC is the use of sub-2 microm particles in combination with elevated pressure and temperature. However, as shown in this study additional efforts are needed to improve transferability as well as column performance.

  13. Removal of lipopolysaccharide from protein solution using nanostructured porous supports bearing lipid membranes

    NASA Astrophysics Data System (ADS)

    Wakita, Masa-aki

    2013-11-01

    Polymeric lipid membranes of N-octadecylchitosan, which consists of 70 mol% of 2-(octadecylamino)-2-deoxy- d-glucopyranose, 17 mol% of 2-amino-2-deoxy- d-glucopyranose, and 13 mol% of 2-acetamido-2-deoxy- d-glucopyranose, were covalently immobilized to carboxylated porous supports composed of chitosan and used for the adsorption of pyrogenic lipopolysaccharide. When human serum albumin solution, including 5 mg mL-1 of albumin and 5.6 ng mL-1 of lipopolysaccharide, was passed through a column packed with the resulting porous supports bearing lipid membranes assembled in nanoscale, lipopolysaccharide was removed to as low as a detection limit of 0.020 ng mL-1 with a quantitative recovery of protein. On the other hand, in the case of directly N-octadecylated porous supports having cationic and hydrophobic ligands which are not assembled as lipid membranes, lipopolysaccharide could not be removed to the detection limit and protein recovery was lower than the porous supports bearing lipid membranes. The difference above as well as difference from conventional adsorbents suggested that the selectivity was attributable to an interaction between the cationic lipid membranes of N-octadecylchitosan and lipopolysaccharide as well as protein. The porous supports bearing lipid membranes were stable in 0.5 M NaOH and 0.1 M HCl at ambient temperature. Considering the confirmed excellent selectivity and chemical stability, their practical use as separation media in the pharmaceutical manufacturing can be expected.

  14. Inhibitory effect of hexane fraction from Myagropsis myagroides on pancreatic α-amylase in vitro.

    PubMed

    Pak, Won-Min; Kim, Koth-Bong-Woo Ri; Kim, Min-Ji; Cho, Ji-Young; Ahn, Dong-Hyun

    2015-03-01

    A Myagropsis myagroides (Mm) methanol extract showed α-amylase inhibitory activity of 13% at a concentration of 5 mg/ml. Results showed that the hexane fraction from the Mm methanol extract exhibited α-amylase inhibitory activity with an IC50 value of 4.24 mg/ml. The hexane fraction was separated using silica-gel column chromatography, and six subfractions were obtained. The fraction eluted with CHCl3:MeOH = 50:1 showed the highest α-amylase inhibitory activity with an IC50 value of 0.72 mg/ml. This fraction was purified using Sephadex LH-20 column chromatography and an octadecyl silica (ODS) Sepak cartridge, obtaining seven subfractions. Fraction (Fr.) 4 also showed a strong α-amylase inhibitory activity with an IC50 value of 0.75 mg/ml. Fr. 4 was purified by Sephadex LH-20 column chromatography and ODS Sepak cartridge, obtaining six subfractions. Fr. 4-2 was identified as sargachromanol I with an IC50 value of 0.40 mg/ml, and the inhibition pattern analyzed from Lineweaver-Burk plots revealed it to be an uncompetitive inhibitor. These results suggest that Mm has potential as a natural antidiabetes agent.

  15. Aqueous Dispersions of Silica Stabilized with Oleic Acid Obtained by Green Chemistry

    PubMed Central

    Nistor, Cristina Lavinia; Ianchis, Raluca; Ghiurea, Marius; Nicolae, Cristian-Andi; Spataru, Catalin-Ilie; Culita, Daniela Cristina; Pandele Cusu, Jeanina; Fruth, Victor; Oancea, Florin; Donescu, Dan

    2016-01-01

    The present study describes for the first time the synthesis of silica nanoparticles starting from sodium silicate and oleic acid (OLA). The interactions between OLA and sodium silicate require an optimal OLA/OLANa molar ratio able to generate vesicles that can stabilize silica particles obtained by the sol-gel process of sodium silicate. The optimal molar ratio of OLA/OLANa can be ensured by a proper selection of OLA and respectively of sodium silicate concentration. The titration of sodium silicate with OLA revealed a stabilization phenomenon of silica/OLA vesicles and the dependence between their average size and reagent’s molar ratio. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) measurements emphasized the successful synthesis of silica nanoparticles starting from renewable materials, in mild condition of green chemistry. By grafting octadecyltrimethoxysilane on the initial silica particles, an increased interaction between silica particles and the OLA/OLANa complex was achieved. This interaction between the oleyl and octadecyl chains resulted in the formation of stable gel-like aqueous systems. Subsequently, olive oil and an oleophylic red dye were solubilized in these stable aqueous systems. This great dispersing capacity of oleosoluble compounds opens new perspectives for future green chemistry applications. After the removal of water and of the organic chains by thermal treatment, mesoporous silica was obtained.

  16. Organosilane grafted silica: Quantitative correlation of microscopic surface characters and macroscopic surface properties

    NASA Astrophysics Data System (ADS)

    Ji, Tuo; Ma, Chi; Brisbin, Logan; Mu, Liwen; Robertson, Christopher G.; Dong, Yalin; Zhu, Jiahua

    2017-03-01

    In polymer composites, organosilanes are often used to modify the surface property of silica nanoparticles and improve the interfacial properties. Surface properties of the modified silica, such as grafting density and consequent surface energy, largely depend on the molecular structure of the silane. Achieving maximum interfacial bonding between the filler and polymer requires precise control of silica surface property. In this work, four silanes with similar molecular structure but different alkyl chain lengths, trimethoxy(propyl)silane, trimethoxy(octyl)silane, hexadecyltrimethoxysilane and trimethoxy(octadecyl)silane, are selected as model agents to study their roles in influencing silica surface property. The grafting density of silane on the silica is well controlled by regulating the reaction conditions. Three main surface characters, silane grafting density, surface energy and surface potential, are measured. More importantly, a linear relationship has been correlated when plotting grafting density vs. surface energy and grafting density vs. surface potential. Utilizing these relationships, a linear model has been developed to predict grafting density and surface energy by simply measuring surface potential. This model has been validated by both commercial silica and synthesized silica particles of different sizes.

  17. LC method for determination of prasugrel and mass spectrometry detection for thermal and alkaline degradation products.

    PubMed

    Rigobello, C; Barden, A T; Steppe, M

    2015-08-01

    A stability-indicating RP-LC method for the determination of prasugrel in tablets was developed and validated. Stress testing of prasugrel was carried out in accordance with ICH guidelines, where the drug was submitted to acidic and basic hydrolysis, oxidative, thermal and photolytic conditions. Prasugrel was unstable under all the conditions and the degradations products were analyzed by HPLC-UV. Furthermore, two main degradation products found under alkaline and thermal conditions were investigated by LC-MS. Based on the fragmentation patterns, two products resulted from hydrolysis of the acetate ester moiety of prasugrel were observed. Due the chemical equilibrium, tautomerism occurs between the ketone and alcohol functions justifying the similar molecular weight and fragment pattern obtained in degradation products analysis. Successful separation was achieved on a RP-18 octadecyl silane column using acetonitrile and triethylamine 0.5% mixture (50:50, v/v) as the mobile phase at 25 degrees C. The flow rate was 1.0 mL/min and the detector wavelength was 263 nm. The method proposed in this work was successfully applied to quality control of prasugrel and contribute to stability assessment of pharmaceutical products containing this drug.

  18. One-Pot Approach to Prepare Organo-silica Hybrid Capillary Monolithic Column with Intact Mesoporous Silica Nanoparticle as Building Block

    PubMed Central

    Liu, Shengju; Peng, Jiaxi; Liu, Zheyi; Liu, Zhongshan; Zhang, Hongyan; Wu, Ren’an

    2016-01-01

    A facile “one-pot” approach to prepare organo-silica hybrid capillary monolithic column with intact mesoporous silica nanoparticle (IMSN) as crosslinker and building block was described. An IMSN crosslinked octadecyl-silica hybrid capillary monolithic column (IMSN-C18 monolithic column) was successfully prepared, and the effects of fabrication conditions (e.g. concentration of intact mesoporous silica nanoparticle, polycondensation temperature, content of vinyltrimethoxysilane and stearyl methacrylate) on the structures of the IMSN-C18 monolithic column were studied in detail. The IMSN-C18 hybrid monolithic column possessed uniform morphology, good mechanical and pH stability (pH 1.1–11), which was applied to the separations of alkyl benzenes, polycyclic aromatic hydrocarbons (PAHs), as well as proteins. The minimum plate height of 10.5 μm (corresponding to 95000 N m−1) for butylbenzene and high reproducibility were achieved. The analysis of tryptic digest of bovine serum albumin (BSA) was carried out on the IMSN-C18 monolithic column by cLC coupled mass spectrometry (cLC-MS/MS), with the protein sequence coverage of 87.5% for BSA, demonstrating its potential application in proteomics. PMID:27698475

  19. Determination of Cd, Co, Cu, Mn, Ni, Pb, and Zn by Inductively Coupled Plasma Mass Spectroscopy or Flame Atomic Absorption Spectrometry after On-line Preconcentration and Solvent Extraction by Flow Injection System

    PubMed

    Bortoli; Gerotto; Marchiori; Mariconti; Palonta; Troncon

    1996-11-01

    The concentrations of Cd, Co, Cu, Mn, Ni, Pb, and Zn in natural and sea waters are too low to be directly determined with by flame atomic absorption spectrometry (FAAS) or graphite furnace atomic absorption spectrometry (GFAAS). Specific sample preparations are requested that make possible the determination of these analytes by preconcentration or extraction. These techniques are affected by severe problems of sample contamination. In this work Cd, Co, Cu, Mn, Ni, Pb, and Zn were determined by inductively coupled plasma mass spectroscopy (ICP-MS) or by atomic absorption spectrometry, in fresh and seawater samples, after on-line preconcentration and following solvent elution with a flow injection system. Bonded silica with octadecyl functional group C18, packed in a microcolumn of 100-μl capacity, was used to collect diethyldithiocarbamate complexes of the heavy metals in aqueous solutions. The metals are complexed with a chelating agent, adsorbed on the C18 column, and eluted with methanol directly in the flow injection system. The methanolic stream can be addressed to FAAS for direct determination of Cu, Ni, and Zn, or collected in a vial for successive analysis by GFAAS. The eluted samples can be also dried in a vacuum container and restored to a little volume with concentrated HNO3 and Milli-Q water for analysis by ICP-MS or GFAAS.

  20. Pressurized CEC with amperometric detection using mixed-mode monolithic column for rapid analysis of chlorophenols and phenol.

    PubMed

    Lu, Lanxiang; Chen, Yankai; Yu, Xiaowei; Wu, Xiangzong; Tang, Fengxiang; Wu, Xiaoping

    2013-07-01

    A simple analysis of chlorophenols (2-chlorophenol, 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol) and phenol was accomplished by coupling a pressurized CEC with amperometric detection (AD). Efficient and reproducible separation of these compounds was achieved within 9 min on a capillary monolithic stationary phase bonded with octadecyl ligands and sulfonate groups, where the selectivity and the retention of analytes can be functionally controlled by optimizing experimental variables, including organic modifier content, mobile phase pH, ionic strength, working electrode potential, separation voltage, and supplementary pressure. A mixed-mode retention mechanism consisting of reverse-phase chromatographic partition, electrostatic repulsion, and electrophoresis is considered to play roles in the separation. The use of ACN-based media seems effectual in preventing the unfavorable irreversible adsorption on both wall and electrode, and offer higher sensitivity and less electrode fouling in AD of phenols. The LODs were in the range from 0.02 to 0.2 μg/mL with a wide linear dynamic range of 5000-fold, while the peak area precision ranged from 3.2 to 7.5%. The feasibility of using this method in real analysis was evaluated by recovery estimates and comparative experiment on spiked tap water samples. Good recoveries of 80-110% were achieved. Additionally, a paired t-test was used to correlate the two methods.

  1. Quantification of glycated N-terminal peptide of hemoglobin using derivatization for multiple functional groups of amino acids followed by liquid chromatography/tandem mass spectrometry.

    PubMed

    Sakaguchi, Yohei; Kinumi, Tomoya; Yamazaki, Taichi; Takatsu, Akiko

    2016-02-01

    A novel method of amino acid analysis using derivatization of multiple functional groups (amino, carboxyl, and phenolic hydroxyl groups) was applied to measure glycated amino acids in order to quantify glycated peptides and evaluate the degree of glycation of peptide. Amino and carboxyl groups of amino acids were derivatized with 1-bromobutane so that the hydrophobicities and basicities of the amino acids, including glycated amino acids, were improved. These derivatized amino acids could be detected with high sensitivity using LC-MS/MS. In this study, 1-deoxyfructosyl-VHLTPE and VHLTPE, which are N-terminal peptides of the β-chains of hemoglobin, were selected as target compounds. After reducing the peptide sample solution with sodium borohydride, the obtained peptides were hydrolyzed with hydrochloric acid. The released amino acids were then derivatized with 1-bromobutane and analyzed with LC-MS/MS. The derivatized amino acids, including glycated amino acids, could be separated using an octadecyl silylated silica column and good sharp peaks were detected. We show a confirmatory experiment that the proposed method can be applied to evaluate the degree of glycation of peptides, using mixtures of glycated and non-glycated peptide.

  2. Development and validation of a liquid chromatography method for anthocyanins in strawberry (Fragaria spp.) and complementary studies on stability, kinetics and antioxidant power.

    PubMed

    Canuto, Gisele A B; Oliveira, Daniel R; da Conceição, Lucas S M; Farah, João P S; Tavares, Marina F M

    2016-02-01

    A RPLC-DAD method for the analysis of eight anthocyanins was developed, validated and applied to strawberry extracts. The chromatographic method was conducted under gradient elution in acidulated water-methanol mobile phase and octadecyl-silica columns. An ultrasound extraction procedure was optimized by a 3(2) factorial design (%HCl in methanol, temperature, and time) and response surface methodology. Method validation was performed according to the following parameters: linearity (R(2)>0.99, p-value<10(-4), F>725), LOD (3-7 μmol L(-1)) and LOQ (9-22 μmol L(-1)), selectivity/specificity (baseline separation of all analytes and peak purity), instrumental precision (<6.4%CV), repeatability (<6.3%CV) and intermediate precision (<9.9%CV), recovery (83-99%), robustness (mobile phase pH, column temperature and flow rate) and stability (high temperatures and storage; 1st order kinetics). The antioxidant power of anthocyanins was measured on-line (ABTS(+) reaction; Trolox as reference). Ten strawberry extracts were quantified (average values: 24.2 μg/g for cyanidin-3-glucoside and 49.1 μg/g for pelargonidin-3-glucoside).

  3. Modeling of alkyl quaternary ammonium cations intercalated into montmorillonite lattice

    SciTech Connect

    Daoudi, El Mehdi; Boughaleb, Yahia; El Gaini, Layla; Meghea, Irina; Bakasse, Mina

    2013-05-15

    Highlights: ► The modification of montmorillonites by three surfactants increases the basal spacing. ► The model proposed show a bilayer conformation for the surfactant ODTMA. ► The DODMA and TOMA surfactants adopt a paraffin type arrangement. ► Behavior of surfactants in interlayer space was confirmed by TGA and ATR analysis. - Abstract: The objective of this work was to study the conformation of the quaternary ammonium cations viz., octadecyl trimethyl ammonium (ODTMA), dioctadecyl dimethyl ammonium (DMDOA) and trioctadecyl methyl ammonium (TOMA) intercalated within montmorillonite. The modified montmorillonite was characterized by X-ray diffraction in small angle (SAXS), thermal analysis (TGA) and infrared spectroscopy of attenuated total reflection (ATR). The modification of organophilic montmorillonites by the three surfactants ODTMA, DMDOA and TOMA increases the basal spacing from their respective intercalated distances of 1.9 nm, 2.6 nm and 3.4 nm respectively. The increase in the spacing due to the basic organic modification was confirmed by the results of thermal analysis (TGA) and infrared spectroscopy (ATR), and also supported by theoretical calculations of longitudinal and transversal chain sizes of these alkyl quaternary ammonium cations.

  4. Synthesis and Characterization of Superhydrophobic, Self-cleaning NIR-reflective Silica Nanoparticles

    PubMed Central

    Sriramulu, Deepa; Reed, Ella Louise; Annamalai, Meenakshi; Venkatesan, Thirumalai Venky; Valiyaveettil, Suresh

    2016-01-01

    Multifunctional coatings offer many advantages towards protecting various surfaces. Here we apply aggregation induced segregation of perylene diimide (PDI) to control the surface morphology and properties of silica nanoparticles. Differentially functionalized PDI was incorporated on the surface of silica nanoparticles through Si-O-Si bonds. The absorption and emission spectra of the resultant functionalised nanoparticles showed monomeric or excimeric peaks based on the amounts of perylene molecules present on the surface of silica nanoparticles. Contact angle measurements on thin films prepared from nanoparticles showed that unfunctionalised nanoparticles were superhydrophilic with a contact angle (CA) of 0°, whereas perylene functionalised silica particles were hydrophobic (CA > 130°) and nanoparticles functionalised with PDI and trimethoxy(octadecyl)silane (TMODS) in an equimolar ratio were superhydrophobic with static CA > 150° and sliding angle (SA) < 10°. In addition, the near infrared (NIR) reflectance properties of PDI incorporated silica nanoparticles can be used to protect various heat sensitive substrates. The concept developed in this paper offers a unique combination of super hydrophobicity, interesting optical properties and NIR reflectance in nanosilica, which could be used for interesting applications such as surface coatings with self-cleaning and NIR reflection properties. PMID:27824064

  5. Temperature-dependent interfacial properties of hydrophobically end-modified poly(2-isopropyl-2-oxazoline)s assemblies at the air/water interface and on solid substrates.

    PubMed

    Obeid, Rodolphe; Park, Jin-Young; Advincula, Rigoberto C; Winnik, Françoise M

    2009-12-15

    We describe herein the properties at the air/water (A/W) interface of hydrophobically end-modified (HM) poly(2-isopropyl-2-oxazoline)s (PiPrOx) bearing an n-octadecyl chain on both termini (telechelic HM-PiPrOx) or on one chain end (semitelechelic HM-PiPrOx) for different subphase temperatures and spreading solvents using the Langmuir film balance technique. The polymer interfacial properties revealed by the pi-A isotherms depend markedly on the architecture and molecular weight of the polymer. On cold water subphases (14 degrees C), diffusion of PiPrOx chains onto water takes place for all polymers in the intermediate compressibility region (5mNm(-1)). At higher subphase temperatures (36 and 48 degrees C), the HM-PiPrOx film exhibited remarkable stability with time. Brewster angle microscopy (BAM) imaging of the A/W interface showed that the polymer assembly was not uniform and that large domains formed, either isolated grains or pearl necklaces, depending on the polymer structure, the concentration of the spreading solution and the subphase temperature. The Langmuir films were transferred onto hydrophilic substrates (silica) by the Langmuir-Blodgett (LB) technique and onto hydrophobic substrates (gold) by Langmuir-Schaefer (LS) film deposition, resulting in the formation of adsorbed particles ranging in size from 200 to 500nm, depending on the polymer architecture and the substrate temperature. The particles presented "Janus"-like hydrophilic/hydrophobic characteristics.

  6. Critical comparison of extraction procedures for the capillary electrophoretic analysis of opiates in hair.

    PubMed

    de Lima, Elizabete C; da Silva, Clóvis L; Gauchée, Magnólia L N; Tavares, Marina F M

    2003-01-01

    This work presents a comparative evaluation of extraction procedures for the capillary analysis of seven opiates (meperidine, morphine, naloxone, tramadol, fentanyl, sufentanyl, and alfentanyl) in human hair. Pieces of hair (50-150 mg) were subjected to acidic hydrolysis (0.25 mmol L(-1) HCl at 45 degrees C, overnight) followed by pH adjustment and either liquid-liquid extraction (LLE) in hexane, petroleum ether, dichloromethane, and ethyl acetate solvents, or solid-phase extraction (SPE) in octadecyl, cyanopropyl, and aminopropyl bonded silica and cation exchange polymeric phases. Excellent recoveries of approximately 70% (naloxone and fentanyl and its analogues), 88% (meperidine), and ca. 100% (morphine and tramadol) were obtained using SPE in a M-fixed-mode cation exchange reversed-phase cartridge (Oasis MCX LP, Waters Corp., Milford, MA, U.S.A.), making this type of procedure eligible for novel clinical and forensic methodologies for hair analysis. The utility of the proposed extraction technique was demonstrated by the analysis of hair extracts from patients using morphine as part of their pain management protocol.

  7. A Simple Method for Automated Solid Phase Extraction of Water Samples for Immunological Analysis of Small Pollutants.

    PubMed

    Heub, Sarah; Tscharner, Noe; Kehl, Florian; Dittrich, Petra S; Follonier, Stéphane; Barbe, Laurent

    2016-01-01

    A new method for solid phase extraction (SPE) of environmental water samples is proposed. The developed prototype is cost-efficient and user friendly, and enables to perform rapid, automated and simple SPE. The pre-concentrated solution is compatible with analysis by immunoassay, with a low organic solvent content. A method is described for the extraction and pre-concentration of natural hormone 17β-estradiol in 100 ml water samples. Reverse phase SPE is performed with octadecyl-silica sorbent and elution is done with 200 µl of methanol 50% v/v. Eluent is diluted by adding di-water to lower the amount of methanol. After preparing manually the SPE column, the overall procedure is performed automatically within 1 hr. At the end of the process, estradiol concentration is measured by using a commercial enzyme-linked immune-sorbent assay (ELISA). 100-fold pre-concentration is achieved and the methanol content in only 10% v/v. Full recoveries of the molecule are achieved with 1 ng/L spiked de-ionized and synthetic sea water samples.

  8. Comprehensive analytical methodology to determine hydrocarbons in marine waters using extraction disks coupled to glass fiber filters and compound-specific isotope analyses.

    PubMed

    Ternon, Eva; Tolosa, Imma

    2015-07-24

    Solid-phase extraction of both aliphatic (AHs) and aromatic polycyclic hydrocarbons (PAHs) from seawater samples was evaluated using a GFF filter stacked upon an octadecyl bonded silica (C18) disk. Stable-isotope measurements were developed on hydrocarbons extracted from both GFF and C18-disks in order to characterize the source of hydrocarbons. A clear partition of hydrocarbon compounds between the dissolved and the particulate phase was highlighted. PAHs showed a higher affinity with the dissolved phase (recoveries efficiency of 48-71%) whereas AHs presented strong affinity with the particulate phase (up to 76% of extraction efficiency). Medium volumes of seawater samples were tested and no breakthrough was observed for a 5L sample. Isotopic fractionation was investigated within all analytical steps but none was evidenced. This method has been applied to harbor seawater samples and very low AH and PAH concentrations were achieved. Due to the low concentration levels of hydrocarbons in the samples, the source of hydrocarbons was determined by molecular indices rather than isotopic measurements and a pyrolytic origin was evidenced. The aliphatic profile also revealed the presence of long-chain linear alkylbenzenes (LABs). The methodology presented here would better fit to polluted coastal environments affected by recent oil spills.

  9. Greening pharmaceutical applications of liquid chromatography through using propylene carbonate-ethanol mixtures instead of acetonitrile as organic modifier in the mobile phases.

    PubMed

    Tache, Florentin; Udrescu, Stefan; Albu, Florin; Micăle, Florina; Medvedovici, Andrei

    2013-03-05

    Substitution of acetonitrile (ACN) as organic modifier in mobile phases for liquid chromatography by mixtures of propylene carbonate (PC) and ethanol (EtOH) may be considered a greener approach for pharmaceutical applications. Such a replacement is achievable without any major compromise in terms of elution order, chromatographic retention, efficiency and peak symmetry. This has been equally demonstrated for reverse phase (RP), ion pair formation (IP) and hydrophilic interaction liquid chromatography (HILIC) separation modes. The impact on the sensitivity induced by the replacement between these organic solvents is discussed for UV-vis and mass spectrometric detection. A comparison between Van Deemter plots obtained under elution conditions based on ACN and PC/EtOH is presented. The alternative elution modes were also compared in terms of thermodynamic parameters, such as standard enthalpy (ΔH⁰) and entropic contributions to the partition between the mobile and the stationary phases, for some model compounds. Van't Hoff plots demonstrated that differences between the thermodynamic parameters are minor when shifting from ACN/water to PC/EtOH/water elution on an octadecyl chemically modified silicagel stationary phase. As long as large volume injection (LVI) of diluents non-miscible with the mobile phase is a recently developed topic having a high potential of greening the sample preparation procedures through elimination of the solvent evaporation stage, this feature was also assessed in the case of ACN replacement by PC/EtOH.

  10. Thermal responsive micelles for dual tumor-targeting imaging and therapy

    NASA Astrophysics Data System (ADS)

    Chen, Haiyan; Li, Bowen; Qiu, Jiadan; Li, Jiangyu; Jin, Jing; Dai, Shuhang; Ma, Yuxiang; Gu, Yueqing

    2013-11-01

    Two kinds of thermally responsive polymers P(FAA-NIPA-co-AAm-co-ODA) and P(FPA-NIPA-co-AAm-co-ODA) containing folate, isopropyl acrylamide and octadecyl acrylate were fabricated through free radical random copolymerization for targeted drug delivery. Then the micelles formed in aqueous solution by self-assembly and were characterized in terms of particle size, lower critical solution temperature (LCST) and a variety of optical spectra. MTT assays demonstrated the low cytotoxicity of the control micelle and drug-loaded micelle on A549 cells and Bel 7402 cells. Then fluorescein and cypate were used as model drugs to optimize the constituents of micelles for drug entrapment efficiency and investigate the release kinetics of micelles in vitro. The FA and thermal co-mediated tumor-targeting efficiency of the two kinds of micelles were verified and compared in detail at cell level and animal level, respectively. These results indicated that the dual-targeting micelles are promising drug delivery systems for tumor-targeting therapy.

  11. Dynamics of β1-Integrins in Living Fibroblasts—Effect of Substratum Wettability

    PubMed Central

    Zlatanov, I.; Groth, T.; Lendlein, A.; Altankov, G.

    2005-01-01

    The dynamics of integrin receptors mobility was studied in living human fibroblasts using fluorescence-labeled β1-integrin monoclonal antibodies. Time-lapse image series were obtained by confocal laser scanning microscopy when cells were adhering on model hydrophilic (clean glass) and hydrophobic (octadecyl-silanized; i.e., ODS) surfaces coated with fibronectin. Direct measurements showed approximately twice-higher velocity of integrins on glass compared to ODS, and these velocities varied in different zones of the cells. A kinetic model and algorithm for quantification of images was developed, and the analysis identified three receptor populations on glass: immobilized (82.76% of all), slow (4.16%), and fast (13.08%), while, on ODS, only two were identified: immobilized (83.36%) and fast (16.64%). Fast integrins in the peripheral zone of cells have maximal velocities of 0.353 ± 0.02 μm/min (n = 48, four cells) on hydrophilic and 0.218 ± 0.02 μm/min (n = 30, three cells) on hydrophobic substrata. The slow population has a velocity of 0.114 μm/min (n = 48, four cells). Further analyses show that these velocities also differ significantly in the peripheral and middle zones of cells in a substrate-dependent fashion. A well-defined circular motion of receptors around the cell center expressed mainly on hydrophobic substrata was monitored and quantified as well. PMID:16126832

  12. Multifunctional poly(alkyl methacrylate) films for dental care.

    PubMed

    Nielsen, Birthe V; Nevell, Thomas G; Barbu, Eugen; Smith, James R; Rees, Gareth D; Tsibouklis, John

    2011-02-01

    Towards the evaluation of non-permanent dental coatings for their capacity to impart dental-care benefits, thin films of a homologous series of comb-like poly(alkyl methacrylate)s (ethyl to octadecyl) have been deposited, from aqueous latex formulations, onto dentally relevant substrates. AFM studies have shown that the thickness (40-300 nm) and surface roughness (8-12 nm) of coherent polymer films are influenced by the degree of polymerization and by the length of the pendant chain. Of the polymers under consideration, poly(butyl methacrylate) formed a close-packed film that conferred to dental substrates a high degree of inhibition to acid-mediated erosion (about 27%), as evaluated by released-phosphate determinations. The potential utility of the coatings to act as anti-sensitivity barriers has been evaluated by determining the hydraulic conductance of coated bovine-dentine substrates; single treatments of dentine discs with poly(butyl methacrylate) or with poly(ethyl methacrylate) effected mean respective reductions in fluid flow of about 23% with respect to water-treated controls; repeated applications of the poly(butyl methacrylate) latex led to mean reductions in fluid flow of about 80%. Chromometric measurements have shown that pellicle-coated hydroxyapatite discs treated with poly(butyl methacrylate), poly(hexyl methacrylate) or poly(lauryl methacrylate) exhibit significant resistance to staining by food chromogens.

  13. Analysis of triacylglycerols on porous graphitic carbon by high temperature liquid chromatography.

    PubMed

    Merelli, Bérangère; De Person, Marine; Favetta, Patrick; Lafosse, Michel

    2007-07-20

    The retention behaviour of several triacylglycerols (TAGs) and fats on Hypercarb, a porous graphitic carbon column (PGC), was investigated in liquid chromatography (LC) under isocratic elution mode with an evaporative light scattering detector (ELSD). Mixtures of chloroform/isopropanol were selected as mobile phase for a suitable retention time to study the influence of temperature. The retention was different between PGC and non-aqueous reversed phase liquid chromatography (NARP-LC) on octadecyl phase. The retention of TAGs was investigated in the interval 30-70 degrees C. Retention was greatly affected by temperature: it decreases as the column temperature increases. Selectivity of TAGs was also slightly influenced by the temperature. Moreover, this chromatographic method is compatible with a mass spectrometer (MS) detector by using atmospheric pressure chemical ionisation (APCI): same fingerprints of cocoa butter and shea butter were obtained with LC-ELSD and LC-APCI-MS. These preliminary results showed that the PGC column could be suitable to separate quickly triacylglycerols in high temperature conditions coupled with ELSD or MS detector.

  14. A Polymeric Fastener can Easily Functionalize Liposome Surfaces with Gadolinium for Enhanced Magnetic Resonance Imaging

    PubMed Central

    Smith, Cartney E.; Shkumatov, Artem; Withers, Sarah G.; Glockner, James F.; Misra, Sanjay; Roy, Edward J.; Wong, Chun-Ho; Zimmerman, Steven C.; Kong, Hyunjoon

    2013-01-01

    Common methods of loading magnetic resonance imaging (MRI) contrast agents into nanoparticles often suffer from challenges related to particle formation, complex chemical modification/purification steps, and reduced contrast efficiency. This study presents a simple, yet advanced process to address these issues by loading gadolinium, an MRI contrast agent, exclusively on a liposome surface using a polymeric fastener. The fastener, so named for its ability to physically link the two functional components together, consisted of chitosan substituted with diethylenetriaminepentaacetic acid (DTPA) to chelate gadolinium, as well as octadecyl chains to stabilize the modified chitosan on the liposome surface. The assembly strategy, mimicking the mechanisms by which viruses and proteins naturally anchor to a cell, provided greater T1 relaxivity than liposomes loaded with gadolinium in both the interior and outer leaflet. Gadolinium-coated liposomes were ultimately evaluated in vivo using murine ischemia models to highlight the diagnostic capability of the system. Taken together, this process decouples particle assembly and functionalization, and therefore has considerable potential to enhance imaging quality while alleviating many of the difficulties associated with multifunctional particle fabrication. PMID:24083377

  15. Adsorption behavior of hydrophobin and hydrophobin/surfactant mixtures at the solid-solution interface.

    PubMed

    Zhang, Xiaoli L; Penfold, Jeffrey; Thomas, Robert K; Tucker, Ian M; Petkov, Jordan T; Bent, Julian; Cox, Andrew

    2011-09-06

    The adsorption of surface-active protein hydrophobin, HFBII, and HFBII/surfactant mixtures at the solid-solution interface has been studied by neutron reflectivity, NR. At the hydrophilic silicon surface, HFBII adsorbs reversibly in the form of a bilayer at the interface. HFBII adsorption dominates the coadsorption of HFBII with cationic and anionic surfactants hexadecyltrimethyl ammonium bromide, CTAB, and sodium dodecyl sulfate, SDS, at concentrations below the critical micellar concentration, cmc, of conventional cosurfactants. For surfactant concentrations above the cmc, HFBII/surfactant solution complex formation dominates and there is little HFBII adsorption. Above the cmc, CTAB replaces HFBII at the interface, but for SDS, there is no affinity for the anionic silicon surface hence there is no resultant adsorption. HFBII adsorbs onto a hydrophobic surface (established by an octadecyl trimethyl silane, OTS, layer on silicon) irreversibly as a monolayer, similar to what is observed at the air-water interface but with a different orientation at the interface. Below the cmc, SDS and CTAB have little impact upon the adsorbed layer of HFBII. For concentrations above the cmc, conventional surfactants (CTAB and SDS) displace most of the HFBII at the interface. For nonionic surfactant C(12)E(6), the pattern of adsorption is slightly different, and although some coadsorption at the interface takes place, C(12)E(6) has little impact on the HFBII adsorption.

  16. High-performance liquid chromatographic determination of azaarenes and their metabolites in groundwater affected by creosote wood preservatives.

    PubMed

    Ondrus, M G; Steinheimer, T R

    1990-06-01

    Polynuclear azaheterocyclic compounds (azaarenes) are nitrogen-containing analogs of polycyclic aromatic hydrocarbons (PAHs). The nitrogen atom in the ring system causes these compounds to be slightly polar and considerably more water soluble than related PAHs. A method using a solid-surface sorption technique to extract and concentrate azaarenes and their principle metabolites present in groundwater that contains creosote waste is described. Analyte isolation and concentration is accomplished by solid-phase extraction on n-octadecyl cartridges followed by instrumental determination involving high-performance liquid chromatography. Separations and detection are achieved using flexible-walled, wide-bore columns with ultraviolet and fluorescence photometric detectors connected in series. Fluorescence detection alone is insufficient because the fluorescence response produced by two-ring azaarenes is limited. Short wavelength (229 nm) absorbance detection provides improved sensitivity for these compounds and peak rationing for more definitive identification. In this study, oxygen-containing metabolites of quinoline, isoquinoline, and acridine are detected in groundwater from hazardous waste sites in Pensacola, Florida and St. Louis Park, Minnesota. Concentrations ranging from mg/L to ng/L are measured. The dependence of measured octanol-water partition coefficients on pH is discussed in the context of the isolation chemistry. As a direct bacterial degradation product of acridine with a relatively long environmental persistence, 9-acridinone may serve as a biogenic marker signaling creosote contamination of groundwater.

  17. High-performance liquid chromatographic determination of azaarenes and their metabolites in groundwater affected by creosote wood preservatives

    SciTech Connect

    Ondrus, M.G.; Steinheimer, T.R. )

    1990-06-01

    Polynuclear azaheterocyclic compounds (azaarenes) are nitrogen-containing analogs of polycyclic aromatic hydrocarbons (PAHs). The nitrogen atom in the ring system causes these compounds to be slightly polar and considerably more water soluble than related PAHs. A method using a solid-surface sorption technique to extract and concentrate azaarenes and their principle metabolites present in groundwater that contains creosote waste is described. Analyte isolation and concentration is accomplished by solid-phase extraction on n-octadecyl cartridges followed by instrumental determination involving high-performance liquid chromatography. Separations and detection are achieved using flexible-walled, wide-bore columns with ultraviolet and fluorescence photometric detectors connected in series. Fluorescence detection alone is insufficient because the fluorescence response produced by two-ring azaarenes is limited. Short wavelength (229 nm) absorbance detection provides improved sensitivity for these compounds and peak rationing for more definitive identification. In this study, oxygen-containing metabolites of quinoline, isoquinoline, and acridine are detected in groundwater from hazardous waste sites in Pensacola, Florida and St. Louis Park, Minnesota. Concentrations ranging from mg/L to ng/L are measured. The dependence of measured octanol-water partition coefficients on pH is discussed in the context of the isolation chemistry. As a direct bacterial degradation product of acridine with a relatively long environmental persistence, 9-acridinone may serve as a biogenic marker signaling creosote contamination of groundwater.

  18. A Case of Occupational Asthma in a Plastic Injection Process Worker

    PubMed Central

    2013-01-01

    Objectives We report a case of death due to asthma attack in a plastic injection process worker with a history of asthma. Methods To assess task relevance, personal history including occupational history and medical records were reviewed. Samples of the substances utilized in the injection process were collected by visiting the patient’s workplace. The work environment with the actual process was reproduced in the laboratory, and the released substances were evaluated. Results The medical records confirmed that the patient’s conventional asthma was in remission. The analysis of the resins discharged from the injection process simulation revealed styrene, which causes occupational asthma, and benzenepropanoic acid, 3,5-bis(1,1-dimethylethyl)-4-hydroxy-, and octadecyl ester. Even though it was not the case in the present study, various harmful substances capable of inducing asthma such as formaldehyde, acrolein, and acetic acid are released during resin processing. Conclusion A worker was likely to occur occupational asthma as a result of the exposure to the harmful substances generated during the plastic injection process. PMID:24472161

  19. Long circulating micelles of an amphiphilic random copolymer bearing cell outer membrane phosphorylcholine zwitterions.

    PubMed

    Zhao, Jing; Chai, Yu-Dong; Zhang, Jing; Huang, Peng-Fei; Nakashima, Kenichi; Gong, Yong-Kuan

    2015-04-01

    Polymeric micelles with cell outer membrane mimetic structure were prepared in water from amphiphilic random copolymers bearing both the hydrophilic phosphorylcholine zwitterions and hydrophobic octadecyl side chains of cell outer membrane. The polymeric micelles showed sizes ranging from 80 nm to 120 nm in hydrodynamic diameter and zeta-potentials from -6.4 mV to -2.4 mV by dynamic light scattering measurements. The micelles loaded with 6-coumarin as a fluorescence probe were stable to investigate their blood circulation and biodistribution. The in vitro phagocytosis results using murine peritoneal macrophages showed 10-fold reduction compared with a reference micelle. The in vivo blood circulation half-life of the polymeric micelles following intravenous administration in New Zealand Rabbits was increased from 0.55 h to 90.5h. More interestingly, tissue distribution results showed that the concentration of the micelles in the kidney is 4-fold higher than that in the liver and other organs 48 h after administration. The results of this work show great promise for designing more effective stealth drug carriers that can minimize reticuloendothelial system clearance and circulate for long time to reach target by using simple cell membrane mimetic random copolymer micelles.

  20. Controlling Proton Delivery through Catalyst Structural Dynamics.

    PubMed

    Cardenas, Allan Jay P; Ginovska, Bojana; Kumar, Neeraj; Hou, Jianbo; Raugei, Simone; Helm, Monte L; Appel, Aaron M; Bullock, R Morris; O'Hagan, Molly

    2016-10-17

    The fastest synthetic molecular catalysts for H2 production and oxidation emulate components of the active site of hydrogenases. The critical role of controlled structural dynamics is recognized for many enzymes, including hydrogenases, but is largely neglected in designing synthetic catalysts. Our results demonstrate the impact of controlling structural dynamics on H2 production rates for [Ni(P(Ph)2 N(C6H4R)2 )2 ](2+) catalysts (R=n-hexyl, n-decyl, n-tetradecyl, n-octadecyl, phenyl, or cyclohexyl). The turnover frequencies correlate inversely with the rates of chair-boat ring inversion of the ligand, since this dynamic process governs protonation at either catalytically productive or non-productive sites. These results demonstrate that the dynamic processes involved in proton delivery can be controlled through modification of the outer coordination sphere, in a manner similar to the role of the protein architecture in many enzymes. As a design parameter, controlling structural dynamics can increase H2 production rates by three orders of magnitude with a minimal increase in overpotential.

  1. Propylammonium nitrate as a solvent for amphiphile self-assembly into micelles, lyotropic liquid crystals, and microemulsions.

    PubMed

    Atkin, Rob; Bobillier, Sophie M C; Warr, Gregory G

    2010-01-28

    The phase behavior and self-assembled microstructures of a range of oligo(oxyethylene)-n-alkyl ether (C(i)E(j)) surfactants has been investigated in propylammonium nitrate (PAN), a room temperature ionic liquid. Micelles and single-phase microemulsions were all found to form at alkyl chain lengths from dodecyl to octadecyl, and lyotropic liquid crystals formed with hexadecyl chains or longer. Small-angle neutron scattering (SANS) shows that self-assembly occurs by solvophobic interactions driving the aggregation of the alkyl chains, but several results indicate that these are weaker in PAN than in water or ethylammonium nitrate, due chiefly to the hydrophobicity of PAN. Longer alkyl chains are needed for lyotropic liquid crystals to form, and higher surfactant concentrations are needed to form a single phase microemulsion. Conductivity shows these microemulsions to be weakly structured, and relatively insensitive to oil or surfactant molecular structure, unlike water-based systems. However, SANS contrast variation reveals a nanosegregation of oil from the alkyl tails of surfactants within the microemulsion, and may suggest a cosurfactant-like role for the propylammonium cation. Molecular areas within microemulsions and lamellar phases are larger than corresponding water- or ethylammonium nitrate-based systems due to the large molecular volume of the solvating PANs.

  2. Porosity in polysilsesquioxane xerogels

    SciTech Connect

    LOY,DOUGLAS A.; SCHNEIDER,DUANE A.; BAUGHER,BRIGITTA M.; RAHIMIAN,KAMYAR

    2000-05-09

    Polysilsesquioxanes, [RSiO{sub 1.5}]{sub n} are a class of hybrid organic-inorganic materials in which silicon atoms are linked with up to three siloxane bonds to other monomer units in the polymer and the organic group is a pendent functionality. Polysilsesquioxanes are prepared by the hydrolysis and condensation of organotrialkoxysilanes (Scheme l). Organotrialkoxysilanes RSi(OR{prime}){sub 3}, have been extensively used as coupling agents for composites or surface treatments for materials. Polysilsesquioxanes have become increasingly popular for generating specialty coatings such as low k dielectric materials for microelectronic applications. While there is extensive information on the formation of polysilsesquioxanes, there has not been a survey of the ability of organotrialkoxysilanes to form gels until recently. The formation of polysilsesquioxanes gels has been shown to be very sensitive to the nature of the organic group. Many monomers will only form soluble oligomers or polymers upon hydrolysis and condensation, even when the reaction is conducted solvent-free with neat monomer and aqueous catalyst. Furthermore, there is little information concerning the influence of the organic group, R, on the porosity of the polysilsesquioxanes gels that are formed. In this paper the authors describe the preparation of polysilsesquioxane gels where R = H, methyl, ethyl, cyanoethyl, vinyl, dodecyl, hexadecyl, octadecyl, chloromethyl, and chloromethylphenyl, and the characterization of the porosity of the respective xerogels. Gels were prepared from the hydrolysis and condensation of organotrimethoxysilanes, RSi(OEt){sub 3}, and organotriethoxy-silanes, RSi(OEt){sub 3}.

  3. Time- and temperature-dependent migration studies of Irganox 1076 from plastics into foods and food simulants.

    PubMed

    Beldì, G; Pastorelli, S; Franchini, F; Simoneau, C

    2012-01-01

    The study provides an exhaustive set of migration data for octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate (Irganox 1076) from low-density polyethylene (LDPE) in several food matrices. Irganox 1076 was used as a model migrant because it represents one of the typical substances used as an antioxidant in food packaging polymers. Kinetic (time-dependent) migration studies of Irganox 1076 were performed for selected foodstuffs chosen with different physical-chemical properties and in relation to the actual European food consumption market. The effect of fat content and of the temperature of storage on the migration from plastic packaging was evaluated. The results show that migration increased with fat content and storage temperature. All data obtained from real foods were also compared with data obtained from simulants tested in the same conditions. In all studied cases, the kinetics in simulants were higher than those in foodstuffs. The work provides data valuable for the extension of the validation of migration model developed on simulants to foodstuffs themselves.

  4. Quantitative determination of the macrolide antibiotics erythromycin, roxithromycin, azithromycin and clarithromycin in human serum by high-performance liquid chromatography using pre-column derivatization with 9-fluorenylmethyloxycarbonyl chloride and fluorescence detection.

    PubMed

    Sastre Toraño, J; Guchelaar, H J

    1998-12-11

    A validated, highly sensitive and precise high-performance liquid chromatographic (HPLC) method for the determination of the macrolides erythromycin, azithromycin, clarithromycin and roxithromycin in human serum is described. A diethyl ether extract, obtained from serum using a saturated sodium carbonate solution, was treated with 9-fluorenylmethyl-oxycarbonyl chloride (FMOC-Cl) for 40 min at 40 degrees C and chromatographed on a base-deactivated octadecyl column, maintained at 50 degrees C during elution, using an eluent composed of acetonitrile-hydrogenphosphate buffer, pH 7.5, with 0.125% triethylamine (3:2, v/v). Fluorescence detection was used at an excitation wavelength of 255 nm and an emission wavelength of 315 nm. Erythromycin, clarithromycin, roxithromycin and azithromycin were found to have retention times of 8.8, 15.7, 17.1 and 20.7 min, respectively. Recoveries ranging from 93 to 104% were found with reproducibility coefficients of variation of 1.1-5%. Mean correlation coefficients of 0.9997, 0.9998, 0.9996 and 0.9994 were found for the linear calibration curves (n = 2) of erythromycin (0.320-16.1 mg/l), roxithromycin (3.24-19.4 mg/l), clarithromycin (0.190-19.4 mg/l) and azithromycin (0.0988-4.94 mg/l), respectively.

  5. Development and validation of a reversed-phase HPLC method for the quantification of paclitaxel in different PLGA nanocarriers.

    PubMed

    Furman, Christophe; Carpentier, Rodolphe; Barczyk, Amélie; Chavatte, Philippe; Betbeder, Didier; Lipka, Emmanuelle

    2017-03-31

    A reversed-phase high-performance liquid chromatography (RP-HPLC) method has been developed and validated for the quantification of paclitaxel encapsulated in biodegradable poly(lactic-co-glycolic) (PLGA) copolymer nanoparticles. This simple (isocratic mode, without additive) and rapid (retention time of the paclitaxel under 4 minutes) methodology permits the detection of low quantities of paclitaxel in nanoparticulate formulations and the determination of the encapsulation efficiency (EE). Analysis was achieved on an octadecyl stationary phase. The isocratic mobile phase consisted of acetonitrile:water 80:20 (v/v) (flow rate = 0.8 mL/min). Stability of free paclitaxel was preliminary studied in those chromatographic conditions. The calibration curve was linear in the concentration range of 2 to 10 μg/mL (R(2) = 0.9994). The method was specific with valuable trueness, repeatability (intra-day precision) and intermediate precision (inter-day precision) based on relative standard deviation (RSD) values (less than 2%). The limits of detection (LOD) and quantification (LOQ) were 0.56 and 1.85 ng/mL respectively. This developed method was successfully employed for quantifying paclitaxel in PLGA 50:50 co-polymer nanoparticles. The accurate knowledge of the encapsulated paclitaxel concentration is essential to define the quantities of PLGA nanoparticles necessary to achieve the in vitro cell viability study. This article is protected by copyright. All rights reserved.

  6. Capillary electrochromatography of selected phenolic compounds of Chamomilla recutita.

    PubMed

    Fonseca, Fabiana N; Tavares, Marina F M; Horváth, Csaba

    2007-06-22

    This article explores the use of capillary electrochromatography for the analysis of chamomile (Chamomilla recutita L.) extracts. After a thorough study of analytical parameters such as mobile and stationary phase composition, applied voltage, and temperature, a methodology to determine 11 bioactive phenolic compounds (coumarins: herniarin, umbelliferone; phenylpropanoids: chlorogenic acid, caffeic acid; flavones: apigenin, apigenin-7-O-glucoside, luteolin, luteolin-7-O-glucoside; flavonols: quercetin, rutin and flavanone: naringenin) in chamomile extracts was proposed. The method was performed in a Hypersil SCX/C18 column with pH 2.8 phosphate buffer at 50 mmol L(-1) containing 50% acetonitrile (pH adjusted before the addition of the organic solvent). All compounds were separated in less than 7.5 min under isocratic conditions. Figures of merit include linearity (peak area versus apigenin concentration) from 50.0-1000 microg/mL (r2=0.995), and intra-day precision of retention time and peak area better than 1.3% CV and 15%, respectively. The limits of detection and quantification for apigenin were 35.0 microg/mL and 150.0 microg/mL, respectively. This article also describes an NMR 1H study, carried out to monitor a new clean-up procedure for extracts containing propyleneglycol, whose components are poorly retained in conventional octadecyl silica cartridges.

  7. Identification of the specific, shutter-like conformational reorientation in a chiroptical switching polycarbodiimide by VCD spectroscopy.

    PubMed

    Merten, Christian; Reuther, James F; DeSousa, Joseph D; Novak, Bruce M

    2014-06-21

    The specific conformational states responsible for the unique, reversible temperature- and solvent-driven chiroptical switching process experienced by poly(N-1-naphthyl-N'-octadecyl-carbodiimide) (PNOC) have been identified using VCD spectroscopy and DFT calculations. The distinct VCD spectra of PNOC corresponding to the two specific conformations were obtained for the polymer dissolved in DCM-d2 (state A) and CDCl3 (predominantly state B). To specifically assign the structures of both conformations, two simplified 7mer models were constructed and optimized using DFT calculations. The theoretical spectra associated with these model conformations show a high level of agreement when compared to the experimental VCD spectra. The two states consist of the naphthyl pendant groups aligned directionally opposing the helical rotation (model A) and aligned with the helicity of the backbone (model B). This pendant reorientation causes very large OR and ECD Cotton effect inversions upon modification to the temperature or solvent composition of dilute (+)-PNOC solutions in specific solvents. In addition, the pendant group equilibrium from state A to B causes a contraction of the helical pitch from the more expanded 5/1 pitch to the more contracted 7/2 pitch resulting in increased disorder of the solvation sphere surrounding the polymer chain.

  8. Effect of EMA and antioxidants on properties of thermoplastic starch blown films

    NASA Astrophysics Data System (ADS)

    Threepopnatkul, P.; Kulsetthanchalee, C.; Sittattrakul, A.; Kaewjinda, E.

    2015-07-01

    The objectives of this study were to investigate the effect of poly(ethylene-co-methyl acrylate) (EMA) at 10, 30 and 50 wt% on the morphological properties, moisture sorption, water vapor permeability and biodegradability of thermoplastic starch (TPS). Urea and formamide were used as a mixed plasticizer. In addition, the effect of antioxidants namely, 3,5-di-tert-butyl-4-hydroxyhydrocinnamate (DTBH), butylated hydroxytoluene (BHT) and bis(octadecyl)hydroxylamine (BOH) at 1 wt% on the properties of TPS/EMA film was investigated. TPS/EMA films were produced by a blown film molding machine and characterized by scanning electron microscropy, moisture sorption, water vapor permeability and biodegradability measurement. Results found that the increment of EMA content in the TPS matrix could improve the water sorption, water vapor permeability and biodegradability properties of TPS/EMA films. For biodegradation, the weight loss of the blended films was directly proportional to TPS content. Regarding the antioxidants effect, the water vapor permeability of TPS/EMA films containing DTBH was higher than the one with BOH and BHT. However, the antioxidants contributed little to the biodegradability of TPS/EMA films and had no effect on the moisture sorption of TPS/EMA films.

  9. Fast profiling ecotoxicity and skin permeability of benzophenone ultraviolet filters using biopartitioning micellar chromatography based on penetrable silica spheres.

    PubMed

    Yin, Chen-ru; Ma, Li-yun; Huang, Jian-geng; Xu, Li; Shi, Zhi-guo

    2013-12-04

    Penetrable silica possesses hierarchical pores, mesopores and penetrable macropores, offering fast mass transfer, satisfactory mechanical strength as well as low column pressure. In the present study, penetrable octadecyl-bonded silica (ODS) was for the first time used as biopartitioning micellar chromatography (BMC) stationary phase to profile ecotoxicity and skin permeability of benzophenone UV-filters. Mobile phase (MP) pH and concentration of polyoxyethylene(23)lauryl ether in the MP were systematically studied. Quantitative retention-activity relationships (QRARs) model was established to correlate retention factors (k) on BMC with bioconcentration factor (BCF) and transdermal rate (TR) of UV-filters. Coefficient of determination (r(2)) of the QRARs model between log BCF and log k were 0.9398-0.9753, while r(2) between TR and log k were 0.7569-0.8434, which demonstrated satisfactory predictive ability of the methodology. It was a powerful tool for fast screening by combining penetrable ODS with BMC, and avoiding column blockage often occurring in BMC.

  10. Determination of phenol pollutants in water at trace levels: Extraction by a reversible graphitized carbon black cartridge

    SciTech Connect

    Di Corcia, A.; Marchese, S.; Samperi, R.

    1994-03-01

    A method for determining the 11 phenols designated as priority pollutants by the U.S. Environmental Protection Agency as the parts-per-trillion level in water sampled from the environment is described. Drinking (2 L), ground (1.5 L), and river (0.5 L) water samples are preconstructed by passing them through a 1 g graphitized carbon black (GCB) reversible cartridge at a flow rate of approximately 70 mL/min. After the GCB cartridge is washed with 1.5 mL methanol to eliminate water, the cartridge is reversed and then back-flushed with an acidic CH{sub 2}Cl{sub 2}-CH{sub 3}OH mixture for eluting phenols. After partial solvent removal, the sample is subjected to reversed-phase liquid chromatography with UV detection by either a conventional or a diode-array detector. Recoveries of phenols added to 2 L of drinking water at levels between 0.05 and 4 {mu}g/L were higher than 90%. Compared with an octadecyl bonded silica (C{sub 18}) cartridge, the GCB cartridge had a far better extraction efficiency for the more highly water-soluble phenols. The extent to which the presence of fulvic acids in water affected the recovery of the phenols considered was investigated. 36 refs., 2 figs., 4 tabs.

  11. Complex kinetic pathway of furfuryl alcohol polymerization catalyzed by green montmorillonite clays.

    PubMed

    Zavaglia, Raffaele; Guigo, Nathanael; Sbirrazzuoli, Nicolas; Mija, Alice; Vincent, Luc

    2012-07-19

    Furfuryl alcohol (FA) which is derived from lignocellulosic biomass polymerizes into poly(furfuryl alcohol) (PFA) under acidic catalysis. A greener and more sustainable catalytic route was proposed in order to replace hazardous acidic catalysts. Organically modified montmorillonite (Org-MMT) and, in comparison, sodium MMT (Na-MMT) are used to evaluate the catalytic effect on the FA polymerization. X-ray diffraction (XRD) and transmission electronic microscopy (TEM) show that clay layers have been exfoliated during polymerization. Additional FTIR spectroscopy measurements confirm that furanic oligomers have intercalated between clay layers by cation exchange. An original combination between chemorheological and model-free kinetic analysis allows highlighting the influence of MMT on the overall polymerization pathway. The octadecyl ammonium cation (ODA) was also used as homogeneous acidic catalyst to highlight the specific role of this interlayer cation present in Org-MMT. Interestingly, FA/Org-MMT polymerizes more rapidly than FA/ODA but initiation of polymerization is slightly shifted to higher temperature due to initial intercalation between MMT layers. Then, the dual acidic character (Lewis + Brönsted) of Org-MMT leads to gelation at early stage of polymerization. The results clearly show that exfoliation of MMT layers increases the efficiency of collisions.

  12. [Optimization of two-dimensional high performance liquid chromatographic columns for highly efficient separation of intact proteins].

    PubMed

    Hong, Guangfeng; Gao, Mingxia; Yan, Guoquan; Guan, Xia; Tao, Qian; Zhang, Xiangmin

    2010-02-01

    In order to optimize two-dimensional liquid chromatographic (2D-LC) columns for highly efficient separation of proteins, several liquid chromatographic columns were investigated and evaluated. Weak anion-exchange (WAX) column was chosen as the first dimension because of its extensive protein separation power. By comparison of different WAX chromatographic columns for human liver protein separation, TSKgel DEAE-5PW column was selected as the first dimension of a 2D-LC system. For the second dimension, ten typical reversed-phase (RP) LC columns (250 mm x 4.6 mm, 5 microm, 30 nm) were investigated and evaluated. Their silica based RP stationary phases were butyl (C4), octyl (C8) or octadecyl (C18). To evaluate the retention behavior and non-specific protein adsorption ability of these ten columns, four neutral compounds (uracil, nitrobenzene, naphthalene and fluorene) and three standard proteins (cytochrome C, myoglobin and albumin from chicken egg white) were adopted and separated by RPLC. Meantime, WAX fractions were used to investigate the separation ability of different alkyl-bonded silica stationary phase columns for complex protein samples. By comparison of column separation efficiency, adsorption of intact proteins and sample analysis, Jupiter 300 C4 column was finally employed for its excellent separation ability. Optimization of WAX and RPLC columns offers reliable foundation for the construction of 2D-LC protein separation systems.

  13. Synthesis of montmorillonite/Fe3O4-OTAB composite capable of using as anisotropic nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Hua; Li, Yingjun; Wang, Shanqiang; Zhou, Yuanlin

    2017-04-01

    The high hydrophobic magnetic montmorillonite (MMT) nanoparticles were synthesized in two solvents (deionized water and ethanol) by using octadecyl trimethylammonium bromide (OTAB) as intercalating agent and Fe3O4 as magnetic nanoparticles. The obtained samples were characterized by FTIR, XRD, EDS, SEM, VSM. When Fe3O4 was loaded before OTAB on MMT, the sample prepared in deionized water exhibited better adsorption than that prepared in ethanol. The order of Fe3O4 and CTAB introduction had great effect on the hydrophobicity, magnetism, and adsorption. Compared with OTAB-MMT-Fe3O4, Fe3O4-MMT-OTAB possessed higher hydrophobicity and higher magnetic response. The contact angle of Fe3O4-MMT-OTAB could reach 84.80° and Fe3O4-MMT-OTAB possessed higher Ms (9.25 emu/g) than OTAB-MMT-Fe3O4 (6.72 emu/g) dose. Fe3O4-MMT-OTAB will become a promising candidate of anisotropic nano-filled powder in polymers by using low magnetic field to obtain the orientation, based on its above excellent properties.

  14. Isolation and identification of urinary metabolites of berberine in rats and humans.

    PubMed

    Qiu, Feng; Zhu, Zhiyong; Kang, Ning; Piao, Shujuan; Qin, Gengyao; Yao, Xinsheng

    2008-11-01

    The urinary metabolites of berberine, an isoquinoline alkaloid isolated from several Chinese herbal medicines, were investigated in rats and humans. Using macroporous adsorption resin chromatography, open octadecyl silane column chromatography and preparative high-performance liquid chromatography, we isolated seven metabolites (HM1-HM7) from human urine and five metabolites (RM1-RM5) from rat urine after oral administration. Their structures were elucidated by enzymatic deconjugation and analyses of mass spectrometry, (1)H NMR, and nuclear Overhauser effect spectroscopy spectra. Besides the three known metabolites demethyleneberberine-2-O-sulfate (HM1 and RM3), jatrorrhizine-3-O-sulfate (HM5), and thalifendine (RM5), six new metabolites were identified, namely, jatrorrhizine-3-O-beta-D-glucuronide (HM2), thalifendine-10-O-beta-D-glucuronide (HM3), berberrubine-9-O-beta-D-glucuronide (HM4 and RM2), 3,10-demethylpalmatine-10-O-sulfate (HM6 and RM4), columbamin-2-O-beta-D-glucuronide (HM7), and demethyleneberberine-2,3-di-O-beta-D-glucuronide (RM1). These findings suggest that berberine undergoes similar biotransformation in rats and humans. Possible metabolic pathways of berberine in rats and humans are proposed.

  15. Concentration of chosen oxycholesterols in plasma of pregnant women with pregnancy-induced hypertension.

    PubMed

    Bodzek, Piotr; Janoszka, Beata; Wielkoszyński, Tomasz; Bodzek, Danuta; Sieroń, Aleksander

    2002-02-01

    Solid-phase extraction (SPE) was applied for isolation of oxycholesterols from plasma lipid extract from pregnant women with hypertension and from a control group. Separation of oxycholesterols fraction was performed in an SD II horizontal chamber (Chromdes, Poland) using silica gel and octadecyl RPC18 silica gel TLC plates (Merck and Machery Nagel). Visualization was carried out under UV light after Liebermann-Burchard reaction specific for cholesterol and its derivatives. The oxycholesterols (5-cholestene-3beta-ol-7-one, sum of 5-cholestene-3beta, 7beta-diol and 5-cholestene-3beta, 7alpha-diol and sum of 5alpha,6alpha-epoxycholestan-3beta-ol and 5beta, 6beta-epoxycholestan-3beta-ol) were quantified by chromatograms scanning in reflectance and fluorescence mode using a CS 9301 densitometer (Shimadzu). The total concentration of the investigated oxycholesterols in the plasma of pregnant women was up to 5000 ng/mL and was statistically significantly higher in women with pregnancy induced hypertension (PIH).

  16. SPE coupled with dispersive liquid-liquid microextraction followed by GC with flame ionization detection for the determination of ultra-trace amounts of benzodiazepines.

    PubMed

    Ghobadi, Masoomeh; Yamini, Yadollah; Ebrahimpour, Behnam

    2014-02-01

    SPE combined with dispersive liquid-liquid microextration was used for the extraction of ultra-trace amounts of benzodiazepines (BZPs) including, diazepam, midazolam, and alprazolam, from ultra-pure water, tap water, fruit juices, and urine samples. The analytes were adsorbed from large volume samples (60 mL) onto octadecyl silica SPE columns. After the elution of the desired compounds from sorbents with 2.0 mL acetone, 0.5 mL of eluent containing 40.0 μL chloroform was injected rapidly into 4.5 mL pure water. After extraction and centrifugation, 2 μL of the sedimented phase was injected into a GC equipped with a flame ionization detector. Several parameters affecting this process were investigated and optimized. Under the optimal conditions, LODs ranged from 0.02 to 0.05 μg/L, a linear dynamic range of 0.1-100 μg/L and relative SDs in the range of 4.4-10.7% were attained. Very high preconcentration factors ranging from 3895-7222 were achieved. The applicability of the method for the extraction of BZPs from different types of complicated matrices, such as tap water, fruit juices, and urine samples, was studied. The obtained results reveal that the proposed method is a good technique for the extraction and determination of BZPs in complex matrices.

  17. Interaction of planar and nonplanar organic contaminants with coal fly ash: Effects of polar and nonpolar solvent solutions

    SciTech Connect

    Burgess, R.M.; Ryba, S.A.; Cantwell, M.G.; Gundersen, J.L.; Tien, R.; Perron, M.M.

    2006-08-15

    Coal fly ash has a very high sorption capacity for a variety of anthropogenic contaminants and has been used to cleanse wastewater of pollutants for approximately 40 years. Like other black carbons, the planar structure of the residual carbon in fly ash results in elevated affinities for planar organic contaminants, such as polycyclic aromatic hydrocarbons (PAHs) and some polychlorinated biphenyls (PCBs). The present study was performed to understand better the mechanisms affecting the strong interaction between planar contaminants and coal fly ash. The removal of 10 PCBs and 10 PAHs by several fly ashes and other sorbents was evaluated under different experimental conditions to highlight the intermolecular forces influencing adsorption. Varying fly ash concentration and solvent system composition indicated that dispersive interactions were most prevalent. For the PCBs, empirical results also were compared to molecular modeling estimates of the energy necessary for the PCB molecule to assume a planar conformation (PCe). The PCe levels ranged from 8 to 25 kcal/mol, depending on the degree of ortho-substituted chlorination of the PCB. A significant correlation between PCe and PCB removal from solution was observed for the fly ashes and activated carbon, whereas the nonplanar sorbent octadecyl (C{sub 18}) indicated no relationship. These findings demonstrate the strong interaction between black carbon fly ash and planar organic contaminants. Furthermore, as exemplified by the PCBs, these results show how this interaction is a function of a contaminant's ability to assume a planar conformation.

  18. On-line coupling of solid-phase extraction to high-performance liquid chromatography for determination of estrogens in environment.

    PubMed

    Wang, Shuo; Huang, Wei; Fang, Guozhen; He, Jinxing; Zhang, Yan

    2008-01-14

    A method based on on-line solid-phase extraction (SPE) coupling to high-performance liquid chromatography (HPLC) for the determination of estrogens has been developed. This method can continuously perform extraction of estrone, estradiol, estriol and diethylstilbestrol from aqueous samples without any other pretreatment, which can then be analyzed by HPLC with a UV detector at 230 nm. A pre-concentration column was adapted with methanol/water for chromatographic separation and two kinds of sorbents were involved, which are octadecyl-bonded silica and cigarette filter. The condition of pH of samples, sample loading flow rate and desorption time were all optimized, and the performances of both two sorbents were satisfactory. The on-line SPE system requires very low maintenance and just involved a switching-valve-filter system and a flow-inject pump, and the operation of the whole SPE-HPLC instrumentation is quite simple. The detection limits for pre-concentrating 50 mL of standard solution using cigarette filter as sorbent ranged from 0.98 to 78.1 ngL(-1). The enhancement factors were in the range of 197-326. The recoveries of estrogens spiked in real water samples ranged from 85 to 112%. The precisions for nine replicate measurements of a standard mixture (5.0 microgL(-1)) were in the range of 1.0-3.4%.

  19. Synthesis and Characterization of Superhydrophobic, Self-cleaning NIR-reflective Silica Nanoparticles

    NASA Astrophysics Data System (ADS)

    Sriramulu, Deepa; Reed, Ella Louise; Annamalai, Meenakshi; Venkatesan, Thirumalai Venky; Valiyaveettil, Suresh

    2016-11-01

    Multifunctional coatings offer many advantages towards protecting various surfaces. Here we apply aggregation induced segregation of perylene diimide (PDI) to control the surface morphology and properties of silica nanoparticles. Differentially functionalized PDI was incorporated on the surface of silica nanoparticles through Si-O-Si bonds. The absorption and emission spectra of the resultant functionalised nanoparticles showed monomeric or excimeric peaks based on the amounts of perylene molecules present on the surface of silica nanoparticles. Contact angle measurements on thin films prepared from nanoparticles showed that unfunctionalised nanoparticles were superhydrophilic with a contact angle (CA) of 0°, whereas perylene functionalised silica particles were hydrophobic (CA > 130°) and nanoparticles functionalised with PDI and trimethoxy(octadecyl)silane (TMODS) in an equimolar ratio were superhydrophobic with static CA > 150° and sliding angle (SA) < 10°. In addition, the near infrared (NIR) reflectance properties of PDI incorporated silica nanoparticles can be used to protect various heat sensitive substrates. The concept developed in this paper offers a unique combination of super hydrophobicity, interesting optical properties and NIR reflectance in nanosilica, which could be used for interesting applications such as surface coatings with self-cleaning and NIR reflection properties.

  20. Stimulation and release from neurons via a dual capillary collection device interfaced to mass spectrometry.

    PubMed

    Fan, Yi; Lee, Chang Young; Rubakhin, Stanislav S; Sweedler, Jonathan V

    2013-11-07

    Neuropeptides are cell to cell signaling molecules that modulate a wide range of physiological processes. Neuropeptide release has been studied in sample sizes ranging from single cells and neuronal clusters, to defined brain nuclei and large brain regions. We have developed and optimized cell stimulation and collection approaches for the efficient measurement of neuropeptide release from neuronal samples using a dual capillary system. The defining feature is a capillary that contains octadecyl-modified silica nanoparticles on its inner wall to capture and extract releasates. This collection capillary is inserted into another capillary used to deliver solutions that chemically stimulate the cells, with solution flowing up the inner capillary to facilitate peptide collection. The efficiency of peptide collection was evaluated using six peptide standards mixed in physiological saline. The extracted peptides eluted from these capillaries were characterized via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with low femtomole detection limits. Using the capillary collection system in small custom-fabricated culturing chambers, individual cultured neurons and neuronal clusters from the model animal Aplysia californica were stimulated with distinct neuronal secretagogues and the releasates were collected and characterized using MALDI-TOF MS.

  1. Analysis of polynuclear aromatic hydrocarbons in olive oil after solid-phase extraction using a dual-layer sorbent cartridge followed by high-performance liquid chromatography with fluorescence detection.

    PubMed

    Stenerson, Katherine K; Shimelis, Olga; Halpenny, Michael R; Espenschied, Ken; Ye, Maochun M

    2015-05-27

    A simple and easy direct solid-phase extraction (SPE) method was developed for the analysis of polynuclear aromatic hydrocarbons (PAHs) in olive oil using a dual-layer cartridge containing activated Florisil and a mixture of octadecyl (C18)-bonded and zirconia-coated silicas. Undiluted olive oil was applied directly to the SPE cartridge, and the sample was eluted with acetonitrile solvent. Background in the extract was found to be low enough for either gas chromatography-mass spectrometry (GC-MS) or high-performance liquid chromatography with fluorescence detection (HPLC-FLD) analysis. Average recoveries for 16 different PAHs from spiked olive oil replicates were >75%, with intraday precisions of <20% relative standard deviation (% RSD). Detection limits ranged from 0.2 to 1.0 μg/kg and, specifically for the PAHs listed in EC Regulation 835/2011, benzo(a)anthracene, chrysene, benzo(b)fluoranthene, and benzo(a)pyrene, were from 0.3 to 0.7 μg/kg. The method was then applied to determine the PAH content present in commercial samples of refined versus extra-virgin olive oils.

  2. Multifunctional electroactive electrospun nanofiber structures from water solution blends of PVA/ODA-MMT and poly(maleic acid-alt-acrylic acid): effects of Ag, organoclay, structural rearrangement and NaOH doping factors

    NASA Astrophysics Data System (ADS)

    Şimşek, Murat; Rzayev, Zakir M. O.; Bunyatova, Ulviya

    2016-06-01

    Novel multifunctional colloidal polymer nanofiber electrolytes were fabricated by green reactive electrospinning nanotechnology from various water solution/dispersed blends of poly (vinyl alcohol-co-vinyl acetate) (PVA)/octadecyl amine-montmorillonite (ODA-MMT) as matrix polymer nanocomposite and poly(maleic acid-alt-acrylic acid) (poly(MAc-alt-AA) and/or its Ag-carrying complex as partner copolymers. Polymer nanofiber electrolytes were characterized using FTIR, XRD, thermal (DSC, TGA-DTG), SEM, and electrical analysis methods. Effects of partner copolymers, organoclay, in situ generated silver nanoparticles (AgNPs), and annealing procedure on physical and chemical properties of polymer composite nanofibers were investigated. The electrical properties (resistance, conductivity, activation energy) of nanofibers with/without NaOH doping agent were also evaluated. This work presented a structural rearrangement of nanofiber mats by annealing via decarboxylation of anhydride units with the formation of new conjugated double bond sites onto partner copolymer main chains. It was also found that the semiconductor behaviors of nanofiber structures were essentially improved with increasing temperature and fraction of partner copolymers as well as presence of organoclay and AgNPs in nanofiber composite.

  3. Electrochemistry and electrogenerated chemiluminescence of films of silicon nanoparticles in aqueous solution

    NASA Astrophysics Data System (ADS)

    Bae, Yoonjung; Lee, Doh C.; Rhogojina, Elena V.; Jurbergs, David C.; Korgel, Brian A.; Bard, Allen J.

    2006-08-01

    Films of octadecyl-capped Si nanoparticles (NPs) (diameter, 3.4 ± 0.7 nm) prepared by drop-coating on indium tin oxide (ITO) showed electrogenerated chemiluminescence (ECL) for both cathodic and anodic potential sweeps in KOH solutions containing peroxydisulfate. The redox potentials of the Si NPs can be estimated as approximately -0.9 and +0.95 V (versus Ag|AgCl) based on the anodic potential for the onset of ECL minus the ECL peak energy. The ECL exhibits a relatively broad spectrum (FWHM = 160 nm) with a peak wavelength of ~670 nm (1.85 eV), similar to the photoluminescence spectra. In electrochemical studies in KOH solution in the absence of peroxydisulfate, an anodic current peak appears at about -1 V (versus Ag|AgCl) following a scan to negative potentials. A similar peak has been observed during the etching of a bulk single crystal Si electrode in alkaline aqueous solution. Unpassivated surface sites of Si NPs seem to be etched at potentials negative of the anodic oxidation peak.

  4. One-pot synthesized functionalized mesoporous silica as a reversed-phase sorbent for solid-phase extraction of endocrine disrupting compounds in milks.

    PubMed

    Gañán, Judith; Morante-Zarcero, Sonia; Pérez-Quintanilla, Damián; Marina, María Luisa; Sierra, Isabel

    2016-01-08

    A new procedure for the determination of 12 naturally occurring hormones and some related synthetic chemicals in milk, commonly used as growth promoters in cattle, is reported. The method is based on liquid-liquid extraction followed by solid-phase extraction (SPE) using a new one-pot synthesized ordered mesoporous silica (of the SBA-15 type) functionalized with octadecyl groups (denoted as SBA-15-C18-CO) as reversed-phase sorbent. The analytes were eluted with methanol and then submitted to HPLC with diode array detection. Under optimal conditions, the method quantification limit for the analytes ranged from 0.023 to 1.36μg/mL. The sorbent affored the extraction of estrone, 17β-estradiol, estriol, progesterone, hexestrol, diethylstilbestrol, 4-androstene-3,17-dione, ethinylestradiol, 17α-methyltestosterone, nandrolone, prednisolone and testosterone with mean recoveries ranging from 72% to 105% (except for diethylstilbestrol) with RSD<11%. These results were comparable and, in some cases, even better than those obtained with other extraction methods, therefore SBA-15-C18-CO mesoporous silica possess a high potential as a reversed-phase sorbent for SPE of the 12 mentioned endocrine disrupting compounds in milk samples.

  5. Cellulose nanocrystals: A layered host candidate for fabricating intercalated nanocomposites.

    PubMed

    Guo, Juan; Du, Wenbo; Wang, Siqun; Yin, Yafang; Gao, Yong

    2017-02-10

    The stacking of cellulose chains along planes and weak intersheet interactions make cellulose nanocrystals (CNCs) promising as a layered host candidate for fabricating intercalated nanocomposites. As a proof-of-concept, we demonstrate the intercalation of alkyls into CNCs through the in situ intercalative chemical reaction between terminal groups of N-octadecyl isocyanates and hydroxyl groups on the (200) planes in CNCs. Results showed that CNCs could intercalate alkyls in a high degree of substitution to form dense brushes on their (200) planes. After intercalation, a significant enlargement of interlayer spacing was observed. Moreover, alkyls were fully extended in all-trans configuration and crystallized in a co-existing organization of αH, βH and βO crystalline forms. This meant that the molecular arrangement in CNCs/alkyl intercalated nanocomposites would involve a bilayer model in which alkyls were in the ordered packing and titled to (200) plane. Furthermore, CNCs/alkyl intercalated nanocomposites possessed increased thermal properties and decreased char residue.

  6. Study of the helium cross-section of unsymmetric disulfide self-assembled monolayers on Au(111)

    NASA Astrophysics Data System (ADS)

    Albayrak, Erol; Karabuga, Semistan; Bracco, Gianangelo; Danışman, M. Fatih

    2016-12-01

    We have investigated the formation of self-assembled monolayers (SAMs) of 11-hydroxyundecyl decyl disulfide (CH3-(CH2)9-S-S-(CH2)11-OH, HDD) and 11-hydroxyundecyl octadecyl disulfide (CH3-(CH2)17-S-S-(CH2)11-OH, HOD) produced by supersonic molecular beam deposition (SMBD). The study has been carried out by means of helium diffraction at very low film coverage. In this regime helium single molecule cross sections have been estimated in a temperature range between 100 K and 450 K. The results show a different behavior above 300 K that has been interpreted as the starting of mobility with the formation of two thiolate moieties either linked by a gold adatom or distant enough to prevent cross section overlapping. Finally, helium diffraction patterns measured at 80 K for the SAMs grown at 200 K are discussed and the results support the proposed hypothesis of molecular dissociation based on the cross section data.

  7. Exploring a direct injection method for microfluidic generation of polymer microgels.

    PubMed

    Wang, Yihe; Tumarkin, Ethan; Velasco, Diego; Abolhasani, Milad; Lau, Willie; Kumacheva, Eugenia

    2013-07-07

    Microfluidics (MFs) offers a promising method for the preparation of polymer microgels with exquisite control over their dimensions, shapes and morphologies. A challenging task in this process is the generation of droplets (precursors for microgels) from highly viscous polymer solutions. Spatial separation of MF emulsification and gelation of the precursor droplets on chip can address this challenge. In the present work, we explored the application of the "direct injection" method for the preparation of microgels by adding a highly concentrated polymer solution or a gelling agent directly into the precursor droplets. In the first system, primary droplets were generated from a dilute aqueous solution of agarose, followed by the injection of the concentrated agarose solution directly in the primary droplets. The secondary droplets served as precursors for microgels. In the second system, primary droplets were generated from the low-viscous solution of methyl-β-cyclodextrin and poly(ethylene glycol) end-terminated with octadecyl hydrophobic groups. Addition of surfactant directly into the primary droplets led to the binding of methyl-β-cyclodextrin to the surfactant, thereby releasing hydrophobized poly(ethylene glycol) to form polymer microgels. Our results show that, when optimized, the direct injection method can be used for microgel preparation from highly viscous liquids and thus this method expands the range of polymers used for MF generation of microgels.

  8. Development of a selective optical sensor for Cr(VI) monitoring in polluted waters.

    PubMed

    Güell, Raquel; Fontàs, Clàudia; Salvadó, Victòria; Anticó, Enriqueta

    2007-07-02

    An optical sensor is described for the sensitive and selective determination of the Cr(VI) ion in aqueous solutions. The optode membrane is prepared by incorporating Aliquat 336 as an ionophore and a chromoionophore (4',5'-dibromofluorescein octadecyl ester) in a poly(vinyl chloride) (PVC) membrane containing ortho-nitrophenyloctyl ether (o-NPOE) as a plasticizer. The response to Cr(VI) is indicated by co-extraction of the target species and of hydrogen ions into the bulk of the membrane yielding large absorbance changes which can easily be measured in the visible spectral range. The optode membrane shows a reversible response in the concentration range of 1.1x10(-5)-1.0x10(-3) M and has been shown to be more selective towards the HCrO4(-) ion than other anions with a selectivity pattern HCrO4(-) > SCN- approximately = ClO4(-) > NO3(-) approximately = I- approximately = NO2(-) > H2PO4(-) approximately = Cl- approximately = SO4(2-). The sensing method developed has successfully been applied to the determination of Cr(VI) in spiked river water as well as in electroplating rinse waters.

  9. Identification, Synthesis, and Field Tests of the Sex Pheromone of Margarodes prieskaensis (Jakubski).

    PubMed

    Burger, Barend V; de Klerk, C André; Morr, Michael; Burger, Wilhelmina J G

    2017-01-01

    Here, we report the identification and synthesis of the sex pheromone of female Margarodes prieskaensis (Jakubski), and the attractiveness of the synthetic pheromone to males in field trapping tests. Volatile organic compounds were collected from virgin females using a sample enrichment probe (SEP). Analyses by gas chromatography coupled to mass spectrometry revealed the presence of only two constituents. By scaling up the SEP, sufficient of the major constituent was collected for (1)H and (13)C nuclear magnetic resonance (NMR) analyses and ancillary NMR techniques. The sex attractant was identified as (2R,4R,6R,8R)-2,4,6,8-tetramethylundecan-1-ol. The enantiomerically pure compound was synthesized from octadecyl (2R,4R,6R,8R)-2,4,6,8-tetramethylundecanoate, a minor component of the uropygial (preen) gland secretion of the domestic goose, Anser domesticus. Field trapping experiments, carried out in vineyards in the Northern Cape Province of South Africa, showed that the synthetic compound was as attractive to winged males of M. prieskaensis as virgin females. The second compound detected was identified as the corresponding acetate, but addition of this did not affect the attractiveness of the major component. We believe this to be the first identification of a sex attractant of the Margarodidae.

  10. Online polar two phase countercurrent chromatography×high performance liquid chromatography for preparative isolation of polar polyphenols from tea extract in a single step.

    PubMed

    Chen, Wei-Bin; Li, Shu-Qi; Chen, Long-Jiang; Fang, Mei-Juan; Chen, Quan-Cheng; Wu, Zhen; Wu, Yun-Long; Qiu, Ying-Kun

    2015-08-01

    Herein, we report an on-line two-dimensional system constructed by counter-current chromatography (CCC) coupling with preparative high-performance liquid chromatography (prep-HPLC) for the separation and purification of polar natural products. The CCC was used as the first dimensional isolation column, where an environmental friendly polar two-phase solvent system of isopropanol and 16% sodium chloride aqueous solution (1:1.2, v/v) was introduced for low toxicity and favorable resolution. In addition, by applying the stop-and-go flow technique, effluents pre-fractionated by CCC was further purified by a preparative column packed with octadecyl silane (ODS) as the second dimension. The interface between the two dimensions was comprised of a 6-port switching valve and an electronically controlled 2-position 10-port switching valve connected with two equivalent holding columns. To be highlighted here, this rationally designed interface for the purpose of smooth desalination, absorption and desorption, successfully solved the solvent compatibility problem between the two dimensional separation systems. The present integrated system was successfully applied in a one-step preparative separation and identification of 10 pure compounds from the water extracts of Tieguanyin tea (Chinese oolong tea). In short, all the results demonstrated that the on-line 2D CCC×LC method is an efficient and green approach for harvesting polar targets in a single step, which showed great promise in drug discovery.

  11. Exploiting Fast Exciton Diffusion in Dye-Doped Polymer Nanoparticles to Engineer Efficient Photoswitching.

    PubMed

    Trofymchuk, Kateryna; Prodi, Luca; Reisch, Andreas; Mély, Yves; Altenhöner, Kai; Mattay, Jochen; Klymchenko, Andrey S

    2015-06-18

    Photoswitching of bright fluorescent nanoparticles opens new possibilities for bioimaging with superior temporal and spatial resolution. However, efficient photoswitching of nanoparticles is hard to achieve using Förster resonance energy transfer (FRET) to a photochromic dye, because the particle size is usually larger than the Förster radius. Here, we propose to exploit the exciton diffusion within the FRET donor dyes to boost photoswitching efficiency in dye-doped polymer nanoparticles. To this end, we utilized bulky hydrophobic counterions that prevent self-quenching and favor communication of octadecyl rhodamine B dyes inside a polymer matrix of poly(D,L-lactide-co-glycolide). Among tested counterions, only perfluorinated tetraphenylborate that favors the exciton diffusion enables high photoswitching efficiency (on/off ratio ∼20). The switching improves with donor dye loading and requires only 0.1-0.3 wt % of a diphenylethene photochromic dye. Our nanoparticles were validated both in solution and at the single-particle level. The proposed concept paves the way to new efficient photoswitchable nanomaterials.

  12. Photoinduced electron transfer and geminate recombination in the group head region of micelles

    NASA Astrophysics Data System (ADS)

    Glusac, Ksenija; Goun, Alexei; Fayer, M. D.

    2006-08-01

    A pump-probe spectroscopic study of photoinduced forward electron transfer and geminate recombination between donors and acceptors located in the head group regions of micelles is presented. The hole donor is octadecyl-rhodamine B (ODRB) and the hole acceptor is N,N-dimethyl-aniline (DMA). The experiments are conducted as a function of the DMA concentration in the dodecyltrimethylammonium bromide and tetradecyltrimethylammonium bromide micelles. In spite of the fact that the absorptions of both the ODRB radical and ground state bleach spectrally overlap with the ODRB excited state absorption, a procedure that makes it possible to determine the geminate recombination dynamics is presented. These experiments are the first to measure the dynamics of geminate recombination in micelles, and the experiments have two orders of magnitude better time resolution than previous studies of forward transfer. The experimental data are compared to statistical mechanics theoretical calculations of both the forward transfer and the geminate recombination. The theory includes important aspects of the topology of the micelle and the diffusion of the donor-acceptors in the micelle head group region. A semiquantitative but nonquantitative agreement between theory and experiments is achieved.

  13. Fusogenic activity of reconstituted newcastle disease virus envelopes: a role for the hemagglutinin-neuraminidase protein in the fusion process.

    PubMed

    Cobaleda, C; Muñoz-Barroso, I; Sagrera, A; Villar, E

    2002-04-01

    Enveloped viruses, such as newcastle disease virus (NDV), make their entry into the host cell by membrane fusion. In the case of NDV, the fusion step requires both transmembrane hemagglutinin-neuraminidase (HN) and fusion (F) viral envelope glycoproteins. The HN protein should show fusion promotion activity. To date, the nature of HN-F interactions is a controversial issue. In this work, we aim to clarify the role of the HN glycoprotein in the membrane fusion step. Four types of reconstituted detergent-free NDV envelopes were used, on differing in their envelope protein contents. Fusion of the different virosomes and erythrocyte ghosts was monitored using the octadecyl rhodamine B chloride assay. Only the reconstituted envelopes having the F protein, even in the absence of HN protein, displayed residual fusion activity. Treatment of such virosomes with denaturing agents affecting the F protein abolished fusion, indicating that the fusion detected was viral protein-dependent. Interestingly, the rate of fusion in the reconstituted systems was similar to that of intact viruses in the presence of the inhibitor of HN sialidase activity 2,3-dehydro-2-deoxy-N-acetylneuraminic acid. The results show that the residual fusion activity detected in the reconstituted systems was exclusively due to F protein activity, with no contribution from the fusion promotion activity of HN protein.

  14. Fluoxetine and norfluoxetine analysis by direct injection of human plasma in a column switching liquid chromatographic system.

    PubMed

    Santos-Neto, Alvaro J; Fernandes, Christian; Rodrigues, José C; Alves, Claudete; Lanças, Fernando M

    2008-01-01

    A column switching LC method is presented for the analysis of fluoxetine (FLU) and norfluoxetine (NFLU) by direct injection of human plasma using a lab-made restricted access media (RAM) column. A RAM-BSA-octadecyl silica (C-18) column (40 mm x 4.6 mm, 10 microm) is evaluated in both backflush and foreflush elution modes and coupled with a C-18 lab-made (50 mm x 4.6 mm, 3 microm) analytical column in order to perform online sample preparation. Direct injection of 100 microL of plasma samples is possible with the developed approach. In addition, reduction of sample handling is obtained when compared with traditional liquid-liquid extraction (LLE) and SPE. The total analysis time is around 20 min. A LOQ of 15 ng/mL is achieved in a concentration range of 15-500 ng/mL, allowing the therapeutic drug monitoring of clinical samples. The precision values achieved are lower than 15% for all the evaluated points with adequate recovery and accuracy. Furthermore, no matrix interferences are found in the analysis and the proposed method shows to be an adequate alternative for analysis of FLU in plasma.

  15. Lipoxygenase inhibitory sphingolipids from Launaea nudicaulis.

    PubMed

    Riaz, Naheed; Parveen, Shehla; Saleem, Muhammad; Ali, Muhammad Shaiq; Malik, Abdul; Ashraf, Muhammad; Afzal, Iftikhar; Jabbar, Abdul

    2012-01-01

    Four new sphingolipids: nudicaulin A [(2S,3S,4R,14E)-2-{[octadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol; 1], nudicaulin B [(2S,3S,4R,14E)-2-{[(2R)-2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol; 2], nudicaulin C [(2S,3S,4R,14E)-2-{[(2R)-2-hydroxyoctadecanoyl]amino}tetraeicos-14-ene-1,3,4-triol-1-O-β-D-glucopyranoside; 3], and nudicaulin D [(2S,3S,4R)-2-{[(2R,3S,12E)-2,3-dihydroxyeicos-12-enoyl]amino}octadecane-1,3,4-triol; 4] together with 1-hexatriacontanol, β-sitosterol, octadecyl 4-hydroxycinnamate, elaidic acid, cholesta-5,22-diene-3,7-diol, oleanolic acid, apigenin, and β-sitosterol 3-O-β-D-glucopyranoside were isolated from the methanolic extract of the whole plant of Launaea nudicaulis. Their structures were elucidated using ¹H and ¹³C NMR spectra and 2D NMR analyses (HMQC, HMBC, and COSY) in combination with mass spectrometry (EI-MS, HR-EI-MS, FAB-MS, and HR-FAB-MS) experiments and comparison with literature data of related compounds. Compounds 1-4 displayed moderate inhibitory potential against enzyme lipoxygenase in concentration-dependent manner with IC₅₀ value ranges 103-193 μM.

  16. A Single Gradient Stability-Indicating Reversed-Phase LC Method for the Estimation of Impurities in Omeprazole and Domperidone Capsules.

    PubMed

    Seshadri, Raja Kumar; Raghavaraju, Thummala Veera; Chakravarthy, Ivon Elisha

    2013-01-01

    A gradient reversed-phase liquid chromatographic (RP-LC) method was developed for the quantitative estimation of impurities in the pharmaceutical dosage form of Omeprazole and Domperidone capsules. The developed method is a stability-indicating test method for the estimation of impurities generated during the formulation and storage of Omeprazole and Domperidone capsules. The chromatographic separation was achieved on a column packed with octadecyl silane, having a column length of 250 mm and diameter of 4.6 mm with a particle size of 5 μm, and by following a gradient program using a combination of a monobasic potassium phosphate buffer (0.05M) and acetonitrile. Since the spectral properties were similar, both compounds' individual impurities were estimated at 285 nm. Forced degradation studies were performed on Omeprazole pellets (enteric coated) and Domperidone pellets (SR coated) encapsulated in size '1' hard gelatin capsules. Omeprazole and Domperidone were degraded using acid hydrolysis (0.1 N hydrochloric acid), base (0.1 N sodium hydroxide), oxidation (50% hydrogen peroxide), heat (105 °C), and UV light (254 nm). The established method was validated and found to be linear, accurate, precise, specific, robust, and rugged.

  17. Solid phase extraction using magnetic core mesoporous shell microspheres with C18-modified interior pore-walls for residue analysis of cephalosporins in milk by LC-MS/MS.

    PubMed

    Liu, Xiaodan; Yu, Yingjia; Zhao, Meiyan; Zhang, Haiying; Li, Yan; Duan, Gengli

    2014-05-01

    A fast and effective extraction method has been developed for measuring the residue of cephalosporins (cefalexin, cefazolin, cefoperazone) in milk by using magnetic core-mesoporous shell microspheres with C18-functionalized interior pore-walls (C18-Fe3O4@mSiO2) as adsorbent. With no need for any protein precipitation procedure, the cephalosporins were directly adsorbed onto the C18-Fe3O4@mSiO2 microspheres through hydrophobic interaction with C18-groups (Octadecyl functional groups) functionalized in the interior walls of mesopore channels while the abundant proteins in milk sample were excluded out of the channel due to the size exclusion effect. Thereafter, the cephalosporins-absorbed C18-Fe3O4@mSiO2 microspheres were rapidly isolated by placing a magnet, and followed by liquid chromatography-tandem mass spectrometry analysis after eluted by methanol. Various parameters which could affect the extraction performance were optimised. The newly developed extraction method was successfully applied in determination of cephalosporin residues in milk samples, offering a valuable alternative to simplify and speed up the sample preparation step.

  18. A redox-responsive mesoporous silica nanoparticle capped with amphiphilic peptides by self-assembly for cancer targeting drug delivery.

    PubMed

    Xiao, Dong; Jia, Hui-Zhen; Ma, Ning; Zhuo, Ren-Xi; Zhang, Xian-Zheng

    2015-06-14

    A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with nearly no leakage in the absence of dithiothreitol (DTT) or glutathione (GSH). With the addition of DTT or GSH, the entrapped drug released quickly due to the cleavage of the disulfide bond. It was found that after the internalization of MSNs by cancer cells via the receptor-mediated endocytosis, the surface amphiphilic peptides and alkyl chain of RRMSN/DOX were removed to induce rapid drug release intracellularly after the cleavage of the disulfide bond, triggered by GSH secreted in cancer cells. This novel intelligent RRMSN/DOX drug delivery system using self-assembly of amphiphilic peptides around the MSNs provides a facile, but effective strategy for the design and development of smart drug delivery for cancer therapy.

  19. HPLC method for analysis of a new 1,4-dihydropyridine: application to pharmacokinetic study in rabbit.

    PubMed

    Javidnia, Katayoun; Miri, Ramin; Jamalian, Azadeh

    2006-02-13

    A high sensitive HPLC assay for plasma analysis of a new 1,4-dihydropyridine (nitrimidodipine) was developed to support the subsequent preclinical development of the compound. To 1 ml of rabbit plasma was added internal standard (3-(4-nitrooxy butyl)-5-ethyl-1,4-dihydro-2,6-dimethyl-4-(1-methyl-5-nitro-2-imidazolyl)-3,5-pyridine dicarboxylate) and 0.5 ml of 1M HCl. The plasma was extracted using 5 ml ethyl acetate which evaporated under gentle stream of nitrogen. The residue was reconstituted in 200 microl mobile phase and 100 microl of aliquots were injected to HPLC system. Chromatographic separation was accomplished on octadecyl column (250 mm x 4.6mm) using a mobile phase consisting of acetonitrile-water (45:55, v/v). The method was sensitive to 2.5 ng/ml in plasma (LOD), acceptable within- and between day reproducibility and a linearity (r2>0.9957) over a concentration range from 5 to 400 ng/ml. The mean extraction efficacy was 90.6% and no interfering peaks of the blank plasma chromatograms were observed. By using the above procedure, a simple, sensitive and convenient HPLC assay for determination, stability evaluation and pharmacokinetic study of nitrimidodipine was developed.

  20. Properties and evaluation of quaternized chitosan/lipid cation polymeric liposomes for cancer-targeted gene delivery.

    PubMed

    Liang, Xiaofei; Li, Xiaoyu; Chang, Jin; Duan, Yourong; Li, Zonghai

    2013-07-09

    Development of high-stability and efficient nonviral vectors with low cytoxicity is important for targeted tumor gene therapy. In this study, cationic polymeric liposomes (CPLs), with similar lipid bilayer structure and high thermal stability, were prepared from polymeric surfactants of quaternized (carboxymethyl)chitosan with different carbon chains (dodecyl, tetradecyl, hexadecyl, and octadecyl). By comparing different factors that influence gene delivery, tetradecyl-quaternized (carboxymethy)chitosan (TQCMC) CPLs, with suitable size (184.4 ± 17.1 nm), ζ potentials (27.5 ± 4.9 mV), and productivity for synthesis TQCMC (weight yield 13.1%), were selected for gene transfection evaluation in various cancer cell lines. Although TQCMC CPLs have lower gene transfection efficiency compared with cationic liposomes (Lipofectamine 2000) in vitro, they displayed higher reporter gene delivery ability for cancer tissues (bearing U87 and SMMC-7721 tumors) in vivo after intravenous injection. TQCMC CPLs also have lower cell cytotoxicity and lower cytokine production or liver injury for BALB/c mice. We conclude that the CPLs are promising gene delivery systems that may be used to target various cancers.

  1. EPR investigation of gamma irradiated single crystal guaifenesin: A combined experimental and computational study

    NASA Astrophysics Data System (ADS)

    Tasdemir, Halil Ugur; Sayin, Ulku; Türkkan, Ercan; Ozmen, Ayhan

    2016-04-01

    Gamma irradiated single crystal of Guaifenesin (Glyceryl Guaiacolate), an important expectorant drug, were investigated with Electron Paramagnetic Resonance (EPR) spectroscopy between 123 and 333 K temperature at different orientations in the magnetic field. Considering the chemical structure and the experimental spectra of the gamma irradiated single crystal of guaifenesin sample, we assumed that alkoxy or alkyl-type paramagnetic species may be produced by irradiation. Depending on this assumption, eight possible alkoxy and alkyl-type radicals were modeled and EPR parameters of these modeled radicals were calculated using the B3LYP/6-311++G(d,p)-level of density functional theory (DFT). Theoretically calculated values of alkyl-type modeled radical(R3) are in good agreement with experimentally determined EPR parameters of single crystal. Furthermore, simulation spectra which are obtained by using the theoretical initial values are well matched with the experimental spectra. It was determined that a stable Cα •H2αCβHβCγH2γ (R3) alkyl radical was produced in the host crystal as a result of gamma irradiation.

  2. Incorporation in lipid microparticles of the UVA filter, butyl methoxydibenzoylmethane combined with the UVB filter, octocrylene: effect on photostability.

    PubMed

    Scalia, Santo; Mezzena, Matteo

    2009-01-01

    The aim of this study was to reduce the photoinstability of butyl methoxydibenzoylmethane (BMDBM), the most widely used UVA filter, by incorporating it in lipid microparticles (LMs) alone or together with the UVB filter octocrylene (OCR), acting also as photostabilizer. Microparticles loaded with BMDBM or with combined BMDBM and OCR were produced by the hot emulsion technique, using glyceryl behenate as lipid material and poloxamer 188 as surfactant. The LMs were characterized by release studies, scanning electron microscopy, and powder X-ray diffractometry. The BMDBM and OCR loading was 15.2% and 10.6%, respectively. In order to reproduce the conditions prevalent in commercial sunscreen products, the photoprotective efficacy of the LMs was evaluated after their introduction in a model cream (oil-in-water emulsion) containing a mixture of UVA and UVB filters. A small but statistically significant decrease in BMDBM photodegradation was obtained when the UVA filter was encapsulated alone into the LMs (the extent of degradation was 28.6% +/-2.4 for non-encapsulated BMDBM and 26.0% +/-2.5 for BMDBM-loaded microparticles). On the other hand, the co-loading of OCR in the LMs produced a more marked reduction in the light-induced decomposition of microencapsulated BMDBM (the UVA filter loss was 21.5% +/-2.2). Therefore, incorporation in lipid microparticles of BMDBM together with the sunscreen OCR is more effective in enhancing the UVA filter photostability than LMs loaded with BMDBM alone.

  3. Liquid crystalline phase as a probe for crystal engineering of lactose: carrier for pulmonary drug delivery.

    PubMed

    Patil, Sharvil S; Mahadik, Kakasaheb R; Paradkar, Anant R

    2015-02-20

    The current work was undertaken to assess suitability of liquid crystalline phase for engineering of lactose crystals and their utility as a carrier in dry powder inhalation formulations. Saturated lactose solution was poured in molten glyceryl monooleate which subsequently transformed into gel. The gel microstructure was analyzed by PPL microscopy and SAXS. Lactose particles recovered from gels after 48 h were analyzed for polymorphism using techniques such as FTIR, XRD, DSC and TGA. Particle size, morphology and aerosolisation properties of prepared lactose were analyzed using Anderson cascade impactor. In situ seeding followed by growth of lactose crystals took place in gels with cubic microstructure as revealed by PPL microscopy and SAXS. Elongated (size ∼ 71 μm) lactose particles with smooth surface containing mixture of α and β-lactose was recovered from gel, however percentage of α-lactose was more as compared to β-lactose. The aerosolisation parameters such as RD, ED, %FPF and % recovery of lactose recovered from gel (LPL) were found to be comparable to Respitose® ML001. Thus LC phase (cubic) can be used for engineering of lactose crystals so as to obtain particles with smooth surface, high elongation ratio and further they can be used as carrier in DPI formulations.

  4. Collaboration: a solution to the challenge of conducting nursing research in cardiac rehabilitation.

    PubMed

    Gallagher, Robyn; Sadler, Leonie; Kirkness, Ann; Belshaw, Julie; Roach, Kellie; Warrington, Darrell

    2013-01-01

    Clinical nurse leaders such as clinical nurse consultants are required to conduct research and incorporate outcomes of this research into their every day practice. However, undertaking research presents issues for cardiac rehabilitation clinical nurse consultants because they may have competing demands, difficulty with finding replacements and may be relatively isolated from other researchers. The solution to this situation is the formation of a collaborative research team with other cardiac rehabilitation clinical nurse consultants, with the inclusion of an experienced university academic as a mentor for the cardiac rehabilitation clinical nurse consultants working in an Area Health Service encompassing both rural and metropolitan hospitals in New South Wales, Australia. The related research project aimed to evaluate and improve the clients' knowledge and practices related to the use of sublingual glyceryl trinitrate. The team's experiences and suggestions for clinical nurse Leaders are presented in this paper. Essential team characteristics include having shared motivation, good communication practices, flexibility and tolerance, an effective team size, achieving success, willingness to accept challenges and an experienced mentor. The benefits of developing a collaborative team for research led by clinical nurse consultants in cardiac rehabilitation by far outweigh the time and effort involved in the process.

  5. Effects of Supplemental Exogenous Emulsifier on Performance, Nutrient Metabolism, and Serum Lipid Profile in Broiler Chickens

    PubMed Central

    Roy, Amitava; Haldar, Sudipto; Mondal, Souvik; Ghosh, Tapan Kumar

    2010-01-01

    The effects of an exogenous emulsifier, glyceryl polyethylene glycol ricinoleate, on performance and carcass traits of broiler chickens were assessed. The emulsifier was added to the diet at dose rates of 0 (control), 1 (E1) and 2 (E2) % of added fat (saturated palm oil). Live weight gain (P < .07) and feed conversion ratio (P < .05) in 39 days were higher in the E1 dietary group. Gain: ME intake and gain: protein intake during the grower phase improved quadratically (P < .05). Gross carcass traits were not affected. Body fat content and fat accretion increased (P < .05) and liver fat content decreased (P < .05) linearly with the level of emulsifier in diet. Fat excretion decreased (P < .001) leading to increased ileal fat digestibility (P < .06) in the E1 group (quadratic response). Metabolizable intake of N (P < .1) and fat (P < .05) increased quadratically due to supplementation of emulsifier in diet. Metabolism of trace elements and serum lipid profiles were not affected. The study revealed that supplementation of exogenous emulsifiers in diets containing moderate quantities of added vegetable fats may substantially improve broiler performance. PMID:20671938

  6. Determination of fatty acid methyl esters derived from algae scenedesmus dimorphus biomass by gc-ms with one-step esterification of free fatty acids and transesterification of glycerolipids.

    PubMed

    Avula, Satya Girish Chandra; Belovich, Joanne; Xu, Yan

    2017-03-21

    Algae can synthesize, accumulate and store large amounts of lipids in its cells, which holds immense potential as a renewable source of biodiesel. In this work, we have developed and validated a GC-MS method for quantitation of fatty acids and glycerolipids in forms of fatty acid methyl esters derived from algae biomass. Algae Scenedesmus dimorphus dry mass was pulverized by mortar and pestle, then, extracted by the modified Folch method and fractionated into free fatty acids and glycerolipids on aminopropyl solid-phase extraction cartridges. Fatty acid methyl esters were produced by an optimized one-step esterification of fatty acids and transesterification of glycerolipids with boron trichloride/methanol. The matrix effect, recoveries and stability of fatty acids and glycerolipids in algal matrix were first evaluated by spiking stable isotopes of pentadecanoic-2,2-d2 acid and glyceryl tri(hexadecanoate-2,2-d2 ) as surrogate analytes and tridecanoic-2,2-d2 acid as internal standard into algal matrix prior to sample extraction. Later, the method was validated in terms of lower limits of quantitation, linear calibration ranges, intra- and inter-assay precision and accuracy using tridecanoic-2,2-d2 acid as internal standard. This method developed has been applied to the quantitation of fatty acid methyl esters from free fatty acid and glycerolipid fractions of algae Scenedesmus dimorphus. This article is protected by copyright. All rights reserved.

  7. Structure and mechanism of Staphylococcus aureus TarM, the wall teichoic acid α-glycosyltransferase

    PubMed Central

    Sobhanifar, Solmaz; Worrall, Liam James; Gruninger, Robert J.; Wasney, Gregory A.; Blaukopf, Markus; Baumann, Lars; Lameignere, Emilie; Solomonson, Matthew; Brown, Eric D.; Withers, Stephen G.; Strynadka, Natalie C. J.

    2015-01-01

    Unique to Gram-positive bacteria, wall teichoic acids are anionic glycopolymers cross-stitched to a thick layer of peptidoglycan. The polyol phosphate subunits of these glycopolymers are decorated with GlcNAc sugars that are involved in phage binding, genetic exchange, host antibody response, resistance, and virulence. The search for the enzymes responsible for GlcNAcylation in Staphylococcus aureus has recently identified TarM and TarS with respective α- and β-(1–4) glycosyltransferase activities. The stereochemistry of the GlcNAc attachment is important in balancing biological processes, such that the interplay of TarM and TarS is likely important for bacterial pathogenicity and survival. Here we present the crystal structure of TarM in an unusual ternary-like complex consisting of a polymeric acceptor substrate analog, UDP from a hydrolyzed donor, and an α-glyceryl-GlcNAc product formed in situ. These structures support an internal nucleophilic substitution-like mechanism, lend new mechanistic insight into the glycosylation of glycopolymers, and reveal a trimerization domain with a likely role in acceptor substrate scaffolding. PMID:25624472

  8. Preparation and characterization of solid lipid nanoparticles loaded with doxorubicin.

    PubMed

    Subedi, Robhash Kusam; Kang, Keon Wook; Choi, Hoo-Kyun

    2009-06-28

    Solid lipid nanoparticles (SLN) loaded with doxorubicin were prepared by solvent emulsification-diffusion method. Glyceryl caprate (Capmul)MCM C10) was used as lipid core, and curdlan as the shell material. Dimethyl sulfoxide (DMSO) was used to dissolve both lipid and drug. Polyethylene glycol 660 hydroxystearate (Solutol)HS15) was employed as surfactant. Major formulation parameters were optimized to obtain high quality nanoparticles. The mean particle size measured by photon correlation spectroscopy (PCS) was 199nm. The entrapment efficiency (EE) and drug loading capacity (DL), determined with fluorescence spectroscopy, were 67.5+/-2.4% and 2.8+/-0.1%, respectively. The drug release behavior was studied by in vitro method. Cell viability assay showed that properties of SLN remain unchanged during the process of freeze-drying. Stability study revealed that lyophilized SLN were equally effective (p<0.05) after 1 year of storage at 4 degrees C. In conclusion, SLN with small particle size, high EE, and relatively high DL for doxorubicin can be obtained by this method.

  9. Solid lipid microparticles containing the sunscreen agent, octyl-dimethylaminobenzoate: effect of the vehicle.

    PubMed

    Tursilli, Rosanna; Piel, Géraldine; Delattre, Luc; Scalia, Santo

    2007-06-01

    Solid lipid microparticles (SLMs) loaded with the sunscreen agent, octyl-dimethylaminobenzoate (ODAB), were prepared in order to achieve enhanced sunscreen photostability. The microparticles were produced by the melt dispersion technique using glyceryl behenate as lipidic material and poloxamer 188 as the emulsifier. The obtained SLMs showed proper features in terms of morphology, size distribution (1.67-15.81 microm) and ODAB loading (16.15+/-0.11%, w/w). The sunscreen release from the SLMs was slower than its dissolution rate and the photodecomposition of ODAB was markedly decreased (>51.3%) by encapsulation into the lipid microparticles. The efficacy of the SLM carrier system was also evaluated after their introduction in model topical formulations (i.e., hydrogel and oil-in-water emulsion). Further in vitro release measurements, performed using Franz diffusion cells with polycarbonate membranes, indicated that the retention capacity of the microparticles was lost after their incorporation into the emulsion, whereas it was retained in the hydrogel. Moreover, the SLMs achieved a reduction of the sunscreen photodegradation in the hydrogel vehicle (the ODAB loss decreased from 87.4% to 59.1%), whereas no significant photoprotective effect was observed in the emulsion. Therefore, the efficacy of the ODAB-loaded SLMs was markedly affected by the vehicle.

  10. St. John's wort reversal of meningeal nociception: a natural therapeutic perspective for migraine pain.

    PubMed

    Galeotti, N; Ghelardini, C

    2013-07-15

    Despite a number of antimigraine drugs belonging to different pharmacological classes are available, there is a huge unmet need for better migraine pharmacotherapy. We here demonstrated the capability of Hypericum perforatum, popularly called St. John's wort (SJW), to relieve meningeal nociception in an animal model induced by administration of the nitric oxide (NO) donors glyceryl trinitrate (GTN) and sodium nitroprusside (SNP). GTN and SNP produced a delayed meningeal inflammation, as showed by the upregulation of interleukin (IL)-1β and inducible NO synthase (iNOS), and a prolonged cold allodynia and heat hyperalgesia with a time-course consistent with NO-induced migraine attacks. A single oral administration of a SJW dried extract (5mg/kg p.o.) counteracted the nociceptive behaviour and the overexpression of IL-1β and iNOS. To clarify the cellular pathways involved, the expression of protein kinase C (PKC) and downstream effectors was detected. NO donors increased expression and phosphorylation of PKCγ, PKCɛ and transcription factors, such as nuclear factor (NF)-κB, cyclic AMP response element binding protein (CREB), Signal Transducer and Activator of Transcription (STAT)-1. All these molecular events were prevented by SJW and hypericin, a SJW main component. In conclusion, SJW counteracted the NO donor-induced pain hypersensitivity and meningeal activation by blocking PKC-mediated pathways involving NF-κB, CREB, STAT1. These results might suggest SJW as an innovative and safe perspective for migraine pain.

  11. Production of hybrid lipid-based particles loaded with inorganic nanoparticles and active compounds for prolonged topical release.

    PubMed

    García-González, C A; Sampaio da Sousa, A R; Argemí, A; López Periago, A; Saurina, J; Duarte, C M M; Domingo, C

    2009-12-01

    The production of particulate hybrid carriers containing a glyceryl monostearate (Lumulse GMS-K), a waxy triglyceride (Cutina HR), silanized TiO(2) and caffeine were investigated with the aim of producing sunscreens with UV-radiation protection properties. Particles were obtained using the supercritical PGSS (Particles from Gas Saturated Solutions) technique. This method takes advantages of the lower melting temperatures of the lipids obtained from the dissolution of CO(2) in the bulk mixture. Experiments were performed at 13 MPa and 345 K, according to previous melting point measurements. Blends containing Lumulse GMS-K and Cutina HR lipids (50 wt%) were loaded with silanized TiO(2) and caffeine in percentile proportions of 6 and 4 wt%, respectively. The particles produced were characterized using several analytical techniques as follows: system crystallinity was checked by X-ray diffraction and differential scanning calorimetry, thermal stability by thermogravimetric analysis, and morphology by scanning and transmission electron microscopy. Further, the UV-shielding ability of TiO(2) after its dispersion in the lipidic matrix was assessed by solid UV-vis spectroscopy. Preliminary results indicated that caffeine-loaded solid lipid particles presented a two-step dissolution profile, with an initial burst of 60 wt% of the loaded active agent. Lipid blends loaded with TiO(2) and caffeine encompassed the UV-filter behavior of TiO(2) and the photoaging prevention properties of caffeine.

  12. Reversion of nitrate tolerance in rat aorta rings by freeze-dried red wine.

    PubMed

    Fusi, Fabio; Sgaragli, Giampietro

    2015-04-01

    Chronically administered organic nitrates induce nitrate tolerance and endothelial dysfunction, which limit their therapeutic use. eNOS uncoupling, ROS over-production, aldehyde dehydrogenase-2 as well as superoxide dismutase (SOD) oxidative inhibition, and cGMP desensitization are thought to play an important role. Natural polyphenols are effective antioxidants, which might counteract the mechanisms leading to nitrate tolerance. The aim of this work was to verify whether freeze-dried (dealcoholized) red wine (FDRW) was able to revert glyceryl trinitrate (GTN) tolerance and endothelial dysfunction induced in rat aorta rings with either GTN or diethyldithiocarbamate (DETCA), an irreversible inhibitor of Cu/Zn SOD. GTN induced a concentration-dependent relaxation of rings pre-contracted with phenylephrine. GTN spasmolysis was significantly reduced in rings pre-incubated with either GTN or DETCA. FDRW, at 2.8 µg of gallic acid equivalents (GAE)/mL concentration, was able to revert partially, though significantly, GTN-induced tolerance but not tolerance and endothelial dysfunction induced by DETCA. This work provides the first evidence in vitro that red wine components, at concentrations comparable to those achieved in human blood after moderate consumption of red wine, revert tolerance to nitrates with a mechanism possibly mediated by SOD.

  13. Investigating critical effects of variegated lubricants, glidants and hydrophilic additives on lag time of press coated ethylcellulose tablets.

    PubMed

    Patadia, Riddhish; Vora, Chintan; Mittal, Karan; Mashru, Rajashree

    2016-01-01

    The research envisaged focuses on vital impacts of variegated lubricants, glidants and hydrophilic additives on lag time of press coated ethylcellulose (EC) tablets using prednisone as a model drug. Several lubricants and glidants such as magnesium stearate, colloidal SiO2, sodium stearyl fumarate, talc, stearic acid, polyethylene glycol (6000) and glyceryl behenate were investigated to understand their effects on lag time by changing their concentrations in outer coat. Further, the effects of hydrophilic additives on lag time were examined for hydroxypropylmethylcellulose (E5), hydroxypropylcellulose (EF and SSL), povidone (K30), copovidone, polyethylene glycol (4000), lactose and mannitol. In vitro drug release testing revealed that each selected lubricant/glidant, if present even at concentration of 0.25% w/w, significantly reduced the lag time of press coated tablets. Specifically, colloidal SiO2 and/or magnesium stearate were detrimental while other lubricants/glidants were relatively less injurious. Among hydrophilic additives, freely water soluble fillers had utmost influence in lag time, whereas, comparatively less impact was observed with polymeric binders. Concisely, glidant and lubricant should be chosen to have minimal impact on lag time and further judicious selection of hydrophilic additives should be exercised for modulating lag time of pulsatile release formulations.

  14. Effects of some lubricants and evaluation of compression parameters on directly compressible powders.

    PubMed

    Uğurlu, Timuçin; Halaçoğlu, Mekin Doğa

    2014-05-01

    The objective of this study was to investigate the effects of conventional lubricants including a new candidate lubricant "Hexagonal boron nitride (HBN)" on direct compression powders. Lubricants such as magnesium stearate, glyceryl behenate, stearic acid, talc and polyethylene glycol6000 were studied in this article. Tablets were manufactured on an instrumented tablet press with various lubricant concentrations. Bulk and tapped densities, and Carr's index parameters were calculated for powders. Tensile strength, cohesion index, lower punch ejection force and lubricant effectiveness values were investigated for tablets. The deformation mechanisms of tablets were studied during compression from the Heckel plots with or without lubricants. Powders formulated with MGST and HBN showed better flow properties based on Carr's index. MGST was found to be the most effective lubricant based on lubricant effectiveness for tablets. HBN was found very close to MGST with the same concentrations. Other lubricants showed less effectiveness than that of MGST and HBN. It is observed that an increase in the concentration of HBN leads to decreased tensile strength and cohesion index values because of its surface-covering property. Despite covering property, HBN had no significant effect on disintegration time. Based on the Heckel plots at the level of 1%, HBN showed the most pronounced plastic character.

  15. Non-Invasive Vagus Nerve Stimulation as Treatment for Trigeminal Allodynia

    PubMed Central

    Oshinsky, Michael L.; Murphy, Angela L.; Hekierski, Hugh; Cooper, Marnie; Simon, Bruce J.

    2014-01-01

    Implanted vagus nerve stimulation (VNS) has been used to treat seizures and depression. In this study, we explore the mechanism of action of non-invasive vagus nerve stimulation (nVNS) for the treatment of trigeminal allodynia. Rats were repeatedly infused with inflammatory mediators directly onto the dura, which leads to chronic trigeminal allodynia. nVNS for 2min decreases periorbital sensitivity in rats with periorbital trigeminal allodynia for up to 3.5hr after stimulation. Using microdialysis, we quantified levels of extracellular neurotransmitters in the trigeminal nucleus caudalis (TNC). Allodynic rats showed a 7.7±0.9 fold increase in extracellular glutamate in the TNC following i.p. administration of the chemical headache trigger, glyceryl trinitrate (GTN; 0.1mg/kg). Allodynic rats, which received nVNS, had only a 2.3±0.4 fold increase in extracellular glutamate following GTN similar to the response in control naive rats. When nVNS was delayed until 120min after GTN treatment, the high levels of glutamate in the TNC were reversed following nVNS. The nVNS stimulation parameters used in this study did not produce significant changes in blood pressure or heart rate. These data suggest that nVNS may be used to treat trigeminal allodynia. PMID:24530613

  16. Characterization of Silver Nanoparticles in Cell Culture Medium Containing Fetal Bovine Serum.

    PubMed

    Hansen, Ulf; Thünemann, Andreas F

    2015-06-23

    Nanoparticles are being increasingly used in consumer products worldwide, and their toxicological effects are currently being intensely debated. In vitro tests play a significant role in nanoparticle risk assessment, but reliable particle characterization in the cell culture medium with added fetal bovine serum (CCM) used in these tests is not available. As a step toward filling this gap, we report on silver ion release by silver nanoparticles and on changes in the particle radii and in their protein corona when incubated in CCM. Particles of a certified reference material, p1, and particles of a commercial silver nanoparticle material, p2, were investigated. The colloidal stability of p1 is provided by the surfactants polyethylene glycol-25 glyceryl trioleate and polyethylene glycol-20 sorbitan monolaurate, whereas p2 is stabilized by polyvinylpyrrolidone. Dialyses of p1 and p2 reveal that their silver ion release rates in CCM are much larger than in water. Particle characterization was performed with asymmetrical flow field-flow fractionation, small-angle X-ray scattering, dynamic light scattering, and electron microscopy. p1 and p2 have similar hydrodynamic radii of 15 and 16 nm, respectively. The silver core radii are 9.2 and 10.2 nm. Gel electrophoresis and subsequent peptide identification reveal that albumin is the main corona component of p1 and p2 after incubation in CCM that consists of Dulbecco's modified Eagle medium with 10% fetal bovine serum added.

  17. In vitro anticancer evaluation of 5-fluorouracil lipid nanoparticles using B16F10 melanoma cell lines

    NASA Astrophysics Data System (ADS)

    Shenoy, Vikram S.; Gude, Rajiv P.; Murthy, Rayasa S. Ramachandra

    2013-05-01

    The present study is aimed to investigate the formulation and in vitro anticancer activities of solid lipid nanoparticles (SLNs) of 5-fluorouracil (5-FU) prepared using glyceryl monostearate (GMS) and cetyl palmitate (CP) by hot homogenization method. The lipids were selected based on the partition coefficient of 5-FU in lipids. The lipid nanoparticles were optimized for process and formulation parameters. The optimized nanoparticles were characterized for their zeta potential, morphology, release kinetics, and anticancer activity. Higher entrapments were achieved using a combination of emulsifiers. The zeta potential of the optimized CP and GMS SLN formulation were -8.26 and -9.35 mV, respectively. Both the optimized formulations were spherical. The in vitro release studies of SLNs of both the lipid carriers followed Peppas-Korsenmeyer equation when carried out at pH 3.5 and 7.4. The chemosensitivity assay carried out in B16F10 cell lines revealed that CP SLNs had better cytotoxicity than 5-FU solution and GMS SLNs at 48 h of incubation. Subtoxic concentration of 5-FU-loaded CP SLNs (0.12 μg/mL) possessed comparable antimigrational activity, colony inhibition activity, and cytopathic as that of 5-FU solution effects. The results indicated that encapsulating 5-FU in CP would be a promising delivery system for delivering 5-FU.

  18. Physical-Chemical Characterization and Formulation Considerations for Solid Lipid Nanoparticles.

    PubMed

    Chauhan, Harsh; Mohapatra, Sarat; Munt, Daniel J; Chandratre, Shantanu; Dash, Alekha

    2016-06-01

    Pure glyceryl mono-oleate (GMO) (lipid) and different batches of GMO commonly used for the preparation of GMO-chitosan nanoparticles were characterized by modulated differential scanning calorimetry (MDSC), cryo-microscopy, and cryo-X-ray powder diffraction techniques. GMO-chitosan nanoparticles containing poloxamer 407 as a stabilizer in the absence and presence of polymers as crystallization inhibitors were prepared by ultrasonication. The effect of polymers (polyvinyl pyrrolidone (PVP), Eudragits, hydroxyl propyl methyl cellulose (HPMC), polyethylene glycol (PEG)), surfactants (poloxamer), and oils (mineral oil and olive oil) on the crystallization of GMO was investigated. GMO showed an exothermic peak at around -10°C while cooling and another exothermic peak at around -12°C while heating. It was followed by two endothermic peaks between 15 and 30 C, indicative of GMO melting. The results are corroborated by cryo-microscopy and cryo-X-ray. Significant differences in exothermic and endothermic transition were observed between different grades of GMO and pure GMO. GMO-chitosan nanoparticles resulted in a significant increase in particle size after lyophilization. MDSC confirmed that nanoparticles showed similar exothermic crystallization behavior of lipid GMO. MDSC experiments showed that PVP inhibits GMO crystallization and addition of PVP showed no significant increase in particle size of solid lipid nanoparticle (SLN) during lyophilization. The research highlights the importance of extensive physical-chemical characterization for successful formulation of SLN.

  19. Lipid nanoparticles based on butyl-methoxydibenzoylmethane: in vitro UVA blocking effect

    NASA Astrophysics Data System (ADS)

    Niculae, G.; Lacatusu, I.; Badea, N.; Meghea, A.

    2012-08-01

    The aim of the present study was to obtain efficient lipid nanoparticles loaded with butyl-methoxydibenzoylmethane (BMDBM) in order to develop cosmetic formulations with enhanced UVA blocking effect. For this purpose, two adequate liquid lipids (medium chain triglycerides and squalene) have been used in combination with two solid lipids (cetyl palmitate and glyceryl stearate) in order to create appropriate nanostructured carriers with a disordered lipid network able to accommodate up to 1.5% BMDBM. The lipid nanoparticles (LNs) were characterized in terms of particle size, zeta potential, entrapment efficiency, loading capacity and in vitro UVA blocking effect. The efficiency of lipid nanoparticles in developing some cosmetic formulations has been evaluated by determining the in vitro erythemal UVA protection factor. In order to quantify the photoprotective effect, some selected cream formulations based on BMDBM-LNs and a conventional emulsion were exposed to photochemical UV irradiation at a low energy to simulate the solar energy during the midday. The results obtained demonstrated the high ability of cream formulations based on BMDBM-LNs to absorb more than 96% of UVA radiation. Moreover, the developed cosmetic formulations manifest an enhanced UVA blocking effect, the erythemal UVA protection factor being four times higher than those specific to conventional emulsions.

  20. Doxycycline hyclate-loaded bleached shellac in situ forming microparticle for intraperiodontal pocket local delivery.

    PubMed

    Phaechamud, Thawatchai; Chanyaboonsub, Nuttapong; Setthajindalert, Orn

    2016-10-10

    Bleached shellac (BS) is a water-insoluble polyester resin made up of sesquiterpenoid acids esterified with hydroxy aliphatic acids. In this study, BS dissolved in N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO) and 2-pyrrolidone was used as the internal phase of oil in oil emulsion using olive oil emulsified with glyceryl monostearate (GMS) as the external phase of in situ forming microparticles (ISM). Doxycycline hyclate (DH)-loaded BS ISMs were tested for emulsion stability, viscosity, rheology, transformation into microparticles, syringeability, drug release, surface topography, in vitro degradation and antimicrobial activities against Staphylococcus aureus, Streptococcus mutans and Porphyromonas gingivalis. All emulsions exhibited pseudoplastic flow and notably low syringeability force. Slower transformation from emulsion into microparticles of ISM prepared with 2-pyrrolidone was owing to slower solvent exchange of this solvent which promoted less porous structure of obtained BS matrix microparticles. The system containing 2-pyrrolidone exhibited a higher degradability than that prepared with DMSO. Developed DH-loaded BS ISMs exhibited a sustainable drug release for 47days with Fickian diffusion and effectively inhibited P. gingivalis, S. mutans and S. aureus. Therefore a DH-loaded BS ISM using olive oil containing GMS as the external phase and 2-pyrrolidone as a solvent was a suitable formulation for periodontitis treatment.

  1. Importance of hydrophobic interaction between a SoxB-type cytochrome c oxidase with its natural substrate cytochrome c-551 and its mutants.

    PubMed

    Kagekawa, Sayaka; Mizukami, Makoto; Noguchi, Shunsuke; Sakamoto, Junshi; Sone, Nobuhito

    2002-08-01

    Cytochrome c-551, the electron donor of SoxB-type cytochrome c oxidase in thermophilic bacilli, can be over-expressed in Bacillus thermodenitrificans cells by tranformation with pSTEc551. Several mutant cytochromes c-551 were prepared by site-directed mutagenesis to this expression plasmid. Among them, several Lys residues were changed to Ala/Ser, and we found that these mutant cytochromes retained their activity as substrates, although their K(m) values were 0.04-0.12 microM, depending on the site replaced. In contrast, the C19A mutant cytochrome, which was produced in Brevibacillus choshinensis as a secretion protein, lost its activity as a substrate, suggesting that the fatty acyl-glyceryl residue covalently bound to the cysteine residue of the wild-type c-551 plays a very important role in the activity. The importance of the hydrophobic fatty acid residue for the binding of cytochrome c-551 to the oxidase was also shown by the loss of substrate activity in deacylated cytochrome c-551. These results show the importance of the hydrophobic interaction between this cytochrome and SoxB-type oxidase, despite the fact that the importance of an electrostatic interaction between cytochrome c and mitochondrial cytochrome aa(3) oxidase has already been established.

  2. Impact of anti-tacking agents on properties of gas-entrapped membrane and effervescent floating tablets.

    PubMed

    Kriangkrai, Worawut; Puttipipatkhachorn, Satit; Sriamornsak, Pornsak; Pongjanyakul, Thaned; Sungthongjeen, Srisagul

    2014-12-01

    Tackiness caused by the gas-entrapped membrane (Eudragit(®)RL 30D) was usually observed during storage of the effervescent floating tablets, leading to failure in floatation and sustained release. In this work, common anti-tacking agents (glyceryl monostearate (GMS) and talc) were used to solve this tackiness problem. The impact of anti-tacking agent on the properties of free films and corresponding floating tablets was investigated. GMS was more effective than talc in reducing tackiness of the film. Addition and increasing amount of anti-tacking agents lowered the film mechanical strength, but the coating films were still strong and flexible enough to resist the generated gas pressure inside the floating tablet. Wettability and water vapor permeability of the film decreased with increasing level of anti-tacking agents as a result of their hydrophobicity. No interaction between anti-tacking agents and polymer was observed as confirmed by Fourier transform infrared spectroscopy, powder X-ray diffractometry, and differential scanning calorimetry studies. Increasing amount of anti-tacking agents decreased time to float and tended to retard drug release of the floating tablets. Floating properties and drug release were also influenced by type of anti-tacking agents. The obtained floating tablets still possessed good floating properties and controlled drug release even though anti-tacking agent had some effects. The results demonstrated that the tackiness problem of the floating tablets could be solved by incorporating anti-tacking agent into the gas-entrapped membrane.

  3. Macroangiopathy--does it play a role in young people?

    PubMed

    Donaghue, K C; Robinson, J; McCredie, R; Fung, A; Silink, M; Celermajer, D S

    1998-01-01

    Using a novel ultrasound method, brachial artery endothelial and smooth muscle physiology were studied in 20 adolescents with IDDM and in 20 nondiabetic subjects matched for age (13-22 years), gender and vessel size. Endothelium-dependent dilatation (EDD) was assessed in response to flow (EDD) and endothelium-independent vasodilatation after sublingual glyceryl trinitrate (GTN). Both EDD and GTN were reduced in those with IDDM compared with controls: 5 vs. 9%, (p = 0.0002) and 14 vs. 21% (p = 0.002). Abnormal EDD was found in 12 IDDM adolescents (diabetes duration 3.3-14.9 years). The mean urinary albumin excretion rate of the diabetic group with abnormal EDD was 5.76 +/- 2.82 vs. 8.05 +/- 4.88 microg/min in those with normal EDD (p = 0.25). In the diabetic adolescents there was no significant correlation observed between the test for early large vessel disease, HbAlc and tests for diabetic microangiopathy.

  4. Effect of liquid crystals with cyclodextrin on the bioavailability of a poorly water-soluble compound, diosgenin, after its oral administration to rats.

    PubMed

    Okawara, Masaki; Hashimoto, Fumie; Todo, Hiroaki; Sugibayashi, Kenji; Tokudome, Yoshihiro

    2014-09-10

    Diosgenin, found in wild yam (Dioscorea villosa), has been shown to ameliorate diabetes and hyperlipidemia, increase cell proliferation in a human 3D skin model, and inhibits melanin production in B16 melanoma cells. It is also an active element in cosmeceutical and dietary supplements. Although the bioavailability of diosgenin is low due to its poor solubility and intestinal permeability, it was subsequently improved using a β-cyclodextrin (β-CD) inclusion complex. Recently liquid crystals (LCs) were shown to enhance the bioavailability of poorly water-soluble drugs. The purpose in the present study was to prepare diosgenin LCs and investigate the interaction between LC and β-CD in order to improve its bioavailability of diosgenin. Crystallinity and particle diameters of LCs in water were determined by small angle X-ray scattering (SAXS) and Zetasizer. Pharmacokinetic parameters were calculated using the plasma content of diosgenin after its oral administration to Wistar rats. Regarding the formation of glyceryl monooleate (GMO) and phytantriol (PHY) LC, SAXS patterns showed the hexagonal and cubic phases, respectively. Bioavailability was significantly enhanced after oral administration of LCs prepared by GMO than after diosgenin alone. The bioavailability was further improved with the combination of LC and β-CD than LC and water.

  5. A monolithic lipase reactor for biodiesel production by transesterification of triacylglycerides into fatty acid methyl esters

    PubMed Central

    Urban, Jiri; Svec, Frantisek; Fréchet, Jean M.J.

    2011-01-01

    An enzymatic reactor with lipase immobilized on a monolithic polymer support has been prepared and used to catalyze the transesterification of triacylglycerides into the fatty acid methyl esters commonly used for biodiesel. A design of experiments procedure was used to optimize the monolithic reactor with variables including control of the surface polarity of the monolith via variations in the length of the hydrocarbon chain in alkyl methacrylate monomer, time of grafting of 1-vinyl-4,4-dimethylazlactone used to activate the monolith, and time used for the immobilization of porcine lipase. Optimal conditions involved the use of a poly(stearyl methacrylate-co-ethylene dimethacrylate) monolith, grafted first with vinylazlactone, then treated with lipase for 2 h to carry out the immobilization of the enzyme. Best conditions for the transesterification of glyceryl tributyrate included a temperature of 37°C and a 10 min residence time of the substrate in the bioreactor. The reactor did not lose its activity even after pumping through it a solution of substrate equaling 1,000 reactor volumes. This enzymatic reactor was also used for the transesterification of triacylglycerides from soybean oil to fatty acid methyl esters thus demonstrating the ability of the reactor to produce biodiesel. PMID:21915852

  6. Curcuminoids-loaded lipid nanoparticles: novel approach towards malaria treatment.

    PubMed

    Nayak, Aditya P; Tiyaboonchai, Waree; Patankar, Swati; Madhusudhan, Basavaraj; Souto, Eliana B

    2010-11-01

    In the present work, curcuminoids-loaded lipid nanoparticles for parenteral administration were successfully prepared by a nanoemulsion technique employing high-speed homogenizer and ultrasonic probe. For the production of nanoparticles, trimyristin, tristerin and glyceryl monostearate were selected as solid lipids and medium chain triglyceride (MCT) as liquid lipid. Scanning electron microscopy (SEM) revealed the spherical nature of the particles with sizes ranging between 120 and 250 nm measured by photon correlation spectroscopy (PCS). The zeta potential of the particles ranged between -28 and -45 mV depending on the nature of the lipid matrix produced, which also influenced the entrapment efficiency (EE) and drug loading capacity (LC) found to be in the range of 80-94% and 1.62-3.27%, respectively. The LC increased reciprocally on increasing the amount of MCT as confirmed by differential scanning calorimetry (DSC). DSC analyses revealed that increasing imperfections within the lipid matrix allowed for increasing encapsulation parameters. Nanoparticles were further sterilized by filtration process which was found to be superior over autoclaving in preventing thermal degradation of thermo-sensitive curcuminoids. The in vivo pharmacodynamic activity revealed 2-fold increase in antimalarial activity of curcuminoids entrapped in lipid nanoparticles when compared to free curcuminoids at the tested dosage level.

  7. Organization and characterization of a biosynthetic gene cluster for bafilomycin from Streptomyces griseus DSM 2608

    PubMed Central

    2013-01-01

    Streptomyces griseus DSM 2608 produces bafilomycin, an antifungal plecomacrolide antibiotic. We cloned and sequenced an 87.4-kb region, including a polyketide synthase (PKS) region, methoxymalonate genes, flavensomycinate genes, and other putative regulatory genes. The 58.5kb of PKS region consisting 12 PKS modules arranged in five different PKS genes, was assumed to be responsible for the biosynthesis of plecomacrolide backbone including 16-membered macrocyclic lactone. All the modules showed high similarities with typical type I PKS genes. However, the starting module of PKS gene was confirmed to be specific for isobutyrate by sequence comparison of an acyltransferase domain. In downstream of PKS region, the genes for methoxymalonate biosynthesis were located, among which a gene for FkbH-like protein was assumed to play an important role in the production of methoxymalonyl-CoA from glyceryl-CoA. Further the genes encoding flavensomycinyl-ACP biosynthesis for the post-PKS tailoring were also found in the upstream of PKS region. By gene disruption experiments of a dehydratase domain of module 12 and an FkbH-like protein, this gene cluster was confirmed to be involved in the biosynthesis of bafilomycin. PMID:23663353

  8. [Serum metabolomics analysis on benign prostate hyperplasia in mice based on liquid chromatography-mass spectrometry].

    PubMed

    Geng, Yue; Sun, Fengxia; Ma, Yu; Deng, Ligang; Lü, Jianyun; Li, Teng; Wang, Congcong

    2014-12-01

    Benign prostatic hyperplasia (BPH) increasingly becomes a common factor affecting the quality of life of aging men. Its pathogenesis has not yet been fully elucidated. Ultra-high pressure liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) was employed to detect the changes of serum metabolites in normal mice, benign prostatic hyperplasia model mice and BPH model mice with finasteride intervention. The serum metabolite profiles of the three groups of mice were analyzed. Partial least squares-discriminant analysis (PLS-DA) was used for group differentiation and biomarker selection. The results showed good distinction among the three groups of mice serum metabolite spectra. Three potential biomarkers, 1-hexadecanoyl-SN-glycero-3-phosphocholine, 1-O-hexadecyl-2-O-acetyl-sn-glyceryl-3-phosphorylcholine and (Z)-13-docosenamide, were discovered and identified. They all indicated the occurrence of benign prostatic hypertrophy is closely related to the disorders of lipid metabolism. Coinpared with the control group, the contents of the first two substances were significantly increased in the serum of BPH model mice, and significantly decreased after intervened by finasteride. The contents of (Z)-13-docosenamide decreased significantly in the serum of model group, and increased after intervened by finasteride. Compared with the control group, the contents of three biomarkers in finasteride group did not recover completely and had significant differences. This study is conductive to open new avenues of diagnosis and medical treatment for BPH.

  9. Evaluating the potential of cubosomal nanoparticles for oral delivery of amphotericin B in treating fungal infection

    PubMed Central

    Yang, Zhiwen; Chen, Meiwan; Yang, Muhua; Chen, Jian; Fang, Weijun; Xu, Ping

    2014-01-01

    The oral administration of amphotericin B (AmB) has a major drawback of poor bioavailability. The aim of this study was to investigate the potential of glyceryl monoolein (GMO) cubosomes as lipid nanocarriers to improve the oral efficacy of AmB. Antifungal efficacy was determined in vivo in rats after oral administration, to investigate its therapeutic use. The human colon adenocarcinoma cell line (Caco-2) was used in vitro to evaluate transport across a model of the intestinal barrier. In vivo antifungal results showed that AmB, loaded in GMO cubosomes, could significantly enhance oral efficacy, compared against Fungizone®, and that during a 2 day course of dosage 10 mg/kg the drug reached effective therapeutic concentrations in renal tissue for treating fungal infections. In the Caco-2 transport studies, GMO cubosomes resulted in a significantly larger amount of AmB being transported into Caco-2 cells, via both clathrin- and caveolae-mediated endocytosis, but not macropinocytosis. These results suggest that GMO cubosomes, as lipid nanovectors, could facilitate the oral delivery of AmB. PMID:24421641

  10. Antimicrobial effects of sanitizers against planktonic and sessile Listeria monocytogenes cells according to the growth phase.

    PubMed

    Chavant, Patrick; Gaillard-Martinie, Brigitte; Hébraud, Michel

    2004-07-15

    This study was designed to investigate the individual or combined effects of sanitizers on survival of planktonic or sessile Listeria monocytogenes cells at different phase of growth. The sanitizers tested included: (i) acetic acid (pH 5.0), (ii) NaOH (pH 12.0), (iii) 10% Na2SO4, (iv) 10% Na2SO4 and acetic acid (pH 5.0), (v) 10% Na2SO4 and NaOH (pH 12.0), (vi) a quaternary ammonium (20 ppm) and (vii) glyceryl monolaurate (75 ppm). Results revealed a great efficacy of alkaline treatments on both sessile and planktonic cells with a slightly higher resistance of 6 h biofilms. Quaternary ammonium appeared very effective in killing more than 98% of cells, but a resistance of 7 days biofilm was observed. Other sanitizers did not succeed in inhibiting totally the pathogen but acted in a similar way on both sessile and planktonic cells. Renewing the medium or not do not seem to be the major cause of a resistance emergence.

  11. Effect of Liquid Crystalline Systems Containing Antimicrobial Compounds on Infectious Skin Bacteria.

    PubMed

    Souza, Carla; Watanabe, Evandro; Aires, Carolina Patrícia; Lara, Marilisa Guimarães

    2016-12-27

    This study aimed (i) to prepare liquid crystalline systems (LCS) of glyceryl monooleate (GMO) and water containing antibacterial compounds and (ii) to evaluate their potential as drug delivery systems for topical treatment of bacterial infections. Therefore, LCS containing CPC (cetylpyridinium chloride) (LCS/CPC) and PHMB (poly(hexamethylene biguanide) hydrochloride) (LCS/PHMB) were prepared and the liquid crystalline phases were identified by polarizing light microscopy 24 h and 7 days after preparation. The in vitro drug release profile and in vitro antibacterial activity of the systems were assessed using the double layer agar diffusion method against Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, Escherichia coli, and Enterococcus faecalis. The interaction between GMO and the drugs was evaluated by a drug absorption study. Stable liquid crystalline systems containing CPC and PHMB were obtained. LCS/PHMB decreased the PHMB release rate and exerted strong antibacterial activity against all the investigated bacteria. In contrast, CPC interacted with GMO so strongly that it became attached to the system; the amount released was not sufficient to exert antibacterial activity. Therefore, the studied liquid crystalline systems were suitable to deliver PHMB, but not CPC. Accordingly, it was demonstrated that GMO interacts with each drug differently, which may interfere in the final efficiency of GMO/water LCS.

  12. Tolterodine Tartrate Proniosomal Gel Transdermal Delivery for Overactive Bladder

    PubMed Central

    Rajabalaya, Rajan; Leen, Guok; Chellian, Jestin; Chakravarthi, Srikumar; David, Sheba R.

    2016-01-01

    The goal of this study was to formulate and evaluate side effects of transdermal delivery of proniosomal gel compared to oral tolterodine tartrate (TT) for the treatment of overactive bladder (OAB). Proniosomal gels are surfactants, lipids and soy lecithin, prepared by coacervation phase separation. Formulations were analyzed for drug entrapment efficiency (EE), vesicle size, surface morphology, attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy, in vitro skin permeation, and in vivo effects. The EE was 44.87%–91.68% and vesicle size was 253–845 nm for Span formulations and morphology showed a loose structure. The stability and skin irritancy test were also carried out for the optimized formulations. Span formulations with cholesterol-containing formulation S1 and glyceryl distearate as well as lecithin containing S3 formulation showed higher cumulative percent of permeation such as 42% and 35%, respectively. In the in vivo salivary secretion model, S1 proniosomal gel had faster recovery, less cholinergic side effect on the salivary gland compared with that of oral TT. Histologically, bladder of rats treated with the proniosomal gel formulation S1 showed morphological improvements greater than those treated with S3. This study demonstrates the potential of proniosomal vesicles for transdermal delivery of TT to treat OAB. PMID:27589789

  13. Vitamin D Deficiency Reduces the Immune Response, Phagocytosis Rate, and Intracellular Killing Rate of Microglial Cells

    PubMed Central

    Onken, Marie Luise; Schütze, Sandra; Redlich, Sandra; Götz, Alexander; Hanisch, Uwe-Karsten; Bertsch, Thomas; Ribes, Sandra; Hanenberg, Andrea; Schneider, Simon; Bollheimer, Cornelius; Sieber, Cornel; Nau, Roland

    2014-01-01

    Meningitis and meningoencephalitis caused by Escherichia coli are associated with high rates of mortality and neurological sequelae. A high prevalence of neurological disorders has been observed in geriatric populations at risk of hypovitaminosis D. Vitamin D has potent effects on human immunity, including induction of antimicrobial peptides (AMPs) and suppression of T-cell proliferation, but its influence on microglial cells is unknown. The purpose of the present study was to determine the effects of vitamin D deficiency on the phagocytosis rate, intracellular killing, and immune response of murine microglial cultures after stimulation with the Toll-like receptor (TLR) agonists tripalmitoyl-S-glyceryl-cysteine (TLR1/2), poly(I·C) (TLR3), lipopolysaccharide (TLR4), and CpG oligodeoxynucleotide (TLR9). Upon stimulation with high concentrations of TLR agonists, the release of tumor necrosis factor alpha (TNF-α) and interleukin 6 (IL-6) was decreased in vitamin D-deficient compared to that in vitamin D-sufficient microglial cultures. Phagocytosis of E. coli K1 after stimulation of microglial cells with high concentrations of TLR3, -4, and -9 agonists and intracellular killing of E. coli K1 after stimulation with high concentrations of all TLR agonists were lower in vitamin D-deficient microglial cells than in the respective control cells. Our observations suggest that vitamin D deficiency may impair the resistance of the brain against bacterial infections. PMID:24686054

  14. Rational design of solid catalysts for the selective use of glycerol as a natural organic building block.

    PubMed

    Jérôme, François; Pouilloux, Yannick; Barrault, Joël

    2008-01-01

    Glycerol is the main co-product of the vegetable oils industry (especially biodiesel). With the rapid development of oleochemistry, the production of glycerol is rapidly increasing and chemists are trying to find new applications of glycerol to encourage a better industrial development of vegetable oils. In this Review, attention is focused on the selective use of glycerol as a safe organic building block for organic chemistry. An overview is given of the different heterogeneous catalytic routes developed by chemists for the successful and environmentally friendly use of glycerol in sustainable organic chemistry. In particular, the effects of different catalyst structural parameters are discussed to clearly highlight how catalysis can help organic chemists to overcome the drawbacks stemming from the use of glycerol as a safe organic building block. It is shown that heterogeneous catalysis offers efficient routes for bypassing the traditional use of highly toxic and expensive epichlorohydrin, 3-chloro-1,2-propanediol, or glycidol, which are usually used as a glyceryl donor in organic chemistry.

  15. Formation and characterization of microcrystalline semiconductor particles on bilayer lipid membranes

    SciTech Connect

    Baral, S.; Zhao, X.K.; Rolandi, R.; Fendler, J.H.

    1987-05-21

    Microcrystalline cadmium, indium, copper, and zinc sulfides were generated in situ on the surface of bilayer lipid membranes (BLMs) prepared from bovine-brain phosphatidylserine (PS), glyceryl monooleate (GMO), and a synthetic, polymerizable surfactant (n-C/sub 15/H/sub 31/CO/sub 2/(CH/sub 2/)/sub 2/)/sub 2/N/sup +/(CH/sub 3/)CH/sub 2/C/sub 6/H/sub 4/CH double bond CH/sub 2/, Cl/sup -/ (STYRS). Semiconductor-containing BLMs remained stable for days. Semiconductor formation on the BLM surface was monitored by optical microscopy, voltage-dependent capacitance measurements, and absorption and intracavity-laser-absorption spectroscopy. Band gap excitation of GMO- BLM-incorporated CdS resulted in the development of photovoltage. Irradiation of CdS incorporated into BLMs formed from STYRS (using a 350-nm cutoff filter) led to absorption losses due to the styrene moiety in the surfactant. Apparently, CdS sensitized the photopolymerization of STRYS BLMs.

  16. Periodic minimal surfaces

    NASA Astrophysics Data System (ADS)

    Mackay, Alan L.

    1985-04-01

    A minimal surface is one for which, like a soap film with the same pressure on each side, the mean curvature is zero and, thus, is one where the two principal curvatures are equal and opposite at every point. For every closed circuit in the surface, the area is a minimum. Schwarz1 and Neovius2 showed that elements of such surfaces could be put together to give surfaces periodic in three dimensions. These periodic minimal surfaces are geometrical invariants, as are the regular polyhedra, but the former are curved. Minimal surfaces are appropriate for the description of various structures where internal surfaces are prominent and seek to adopt a minimum area or a zero mean curvature subject to their topology; thus they merit more complete numerical characterization. There seem to be at least 18 such surfaces3, with various symmetries and topologies, related to the crystallographic space groups. Recently, glyceryl mono-oleate (GMO) was shown by Longley and McIntosh4 to take the shape of the F-surface. The structure postulated is shown here to be in good agreement with an analysis of the fundamental geometry of periodic minimal surfaces.

  17. Molecular dynamics approach to water structure of HII mesophase of monoolein

    NASA Astrophysics Data System (ADS)

    Kolev, Vesselin; Ivanova, Anela; Madjarova, Galia; Aserin, Abraham; Garti, Nissim

    2012-02-01

    The goal of the present work is to study theoretically the structure of water inside the water cylinder of the inverse hexagonal mesophase (HII) of glyceryl monooleate (monoolein, GMO), using the method of molecular dynamics. To simplify the computational model, a fixed structure of the GMO tube is maintained. The non-standard cylindrical geometry of the system required the development and application of a novel method for obtaining the starting distribution of water molecules. A predictor-corrector schema is employed for generation of the initial density of water. Molecular dynamics calculations are performed at constant volume and temperature (NVT ensemble) with 1D periodic boundary conditions applied. During the simulations the lipid structure is kept fixed, while the dynamics of water is unrestrained. Distribution of hydrogen bonds and density as well as radial distribution of water molecules across the water cylinder show the presence of water structure deep in the cylinder (about 6 Å below the GMO heads). The obtained results may help understanding the role of water structure in the processes of insertion of external molecules inside the GMO/water system. The present work has a semi-quantitative character and it should be considered as the initial stage of more comprehensive future theoretical studies.

  18. Lateral epicondylalgia: midlife crisis of a tendon.

    PubMed

    Luk, James K H; Tsang, Raymond C C; Leung, H B

    2014-04-01

    The pathogenesis and management of lateral epicondylalgia, or tennis elbow, a common ailment affecting middle-aged subjects of both genders continue to provoke controversy. Currently it is thought to be due to local tendon pathology, pain system changes, and motor system impairment. Its diagnosis is usually clinical, based on a classical history, as well as symptoms and signs. In selected cases, additional imaging (X-rays, ultrasound, and magnetic resonance imaging) can help to confirm the diagnosis. Different treatment modalities have been described, including the use of orthotics, non-steroidal anti-inflammatory drugs, steroid injections, topical glyceryl trinitrate, exercise therapy, manual therapy, ultrasound therapy, laser therapy, extracorporeal shockwave therapy, acupuncture, taping, platelet-rich plasma injections, hyaluronan gel injections, botulinum toxin injections, and surgery. Nevertheless, evidence to select the best treatment is lacking and the choice of therapy depends on the experience of the management team, availability of the equipment and expertise, and patient response. This article provides a snapshot of current medical practice for lateral epicondylalgia management.

  19. An effective biphase system accelerates hesperidinase-catalyzed conversion of rutin to isoquercitrin

    PubMed Central

    Wang, Jun; Gong, An; Yang, Cai-Feng; Bao, Qi; Shi, Xin-Yi; Han, Bei-Bei; Wu, Xiang-Yang; Wu, Fu-An

    2015-01-01

    Isoquercitrin is a rare, natural ingredient with several biological activities that is a key precursor for the synthesis of enzymatically modified isoquercitrin (EMIQ). The enzymatic production of isoquercitrin from rutin catalyzed by hesperidinase is feasible; however, the bioprocess is hindered by low substrate concentration and a long reaction time. Thus, a novel biphase system consisting of [Bmim][BF4]:glycine-sodium hydroxide (pH 9) (10:90, v/v) and glyceryl triacetate (1:1, v/v) was initially established for isoquercitrin production. The biotransformation product was identified using liquid chromatography-mass spectrometry, and the bonding mechanism of the enzyme and substrate was inferred using circular dichroism spectra and kinetic parameters. The highest rutin conversion of 99.5% and isoquercitrin yield of 93.9% were obtained after 3 h. The reaction route is environmentally benign and mild, and the biphase system could be reused. The substrate concentration was increased 2.6-fold, the reaction time was reduced to three tenths the original time. The three-dimensional structure of hesperidinase was changed in the biphase system, which α-helix and random content were reduced and β-sheet content was increased. Thus, the developed biphase system can effectively strengthen the hesperidinase-catalyzed synthesis of isoquercitrin with high yield. PMID:25731802

  20. Supercritical fluid precipitation of ketoprofen in novel structured lipid carriers for enhanced mucosal delivery--a comparison with solid lipid particles.

    PubMed

    Gonçalves, V S S; Matias, A A; Rodríguez-Rojo, S; Nogueira, I D; Duarte, C M M

    2015-11-10

    Structured lipid carriers based on mixture of solid lipids with liquid lipids are the second generation of solid lipid particles, offering the advantage of improved drug loading capacity and higher storage stability. In this study, structured lipid carriers were successfully prepared for the first time by precipitation from gas saturated solutions. Glyceryl monooleate (GMO), a liquid glycerolipid, was selected in this work to be incorporated into three solid glycerolipids with hydrophilic-lipophilic balance (HLB) ranging from 1 to 13, namely Gelucire 43/01™, Geleol™ and Gelucire 50/13™. In general, microparticles with a irregular porous morphology and a wide particle size distribution were obtained. The HLB of the individual glycerolipids might be a relevant parameter to take into account during the processing of solid:liquid lipid blends. As expected, the addition of a liquid lipid into a solid lipid matrix led to increased stability of the lipid carriers, with no significant modifications in their melting enthalpy after 6 months of storage. Additionally, Gelucire 43/01™:GMO particles were produced with different mass ratios and loaded with ketoprofen. The drug loading capacity of the structured lipid carriers increased as the GMO content in the particles increased, achieving a maximum encapsulation efficiency of 97% for the 3:1 mass ratio. Moreover, structured lipid carriers presented an immediate release of ketoprofen from its matrix with higher permeation through a mucous-membrane model, while solid lipid particles present a controlled release of the drug with less permeation capacity.

  1. Long-term sustained-released in situ gels of a water-insoluble drug amphotericin B for mycotic arthritis intra-articular administration: preparation, in vitro and in vivo evaluation.

    PubMed

    Shan-Bin, Guo; Yue, Tian; Ling-Yan, Jian

    2015-04-01

    Amphotericin B (AMB) was often used in intra-articular injection administration for fungal arthritis, because it could often bring a satisfactory therapeutic efficacy and a minimum systemic toxic side effect. However, because of the multiple operations and the frequent injections, the compliance of the patients was bad. Therefore, to develop a long-term sustained-released preparation of AMB for mycotic arthritis intra-articular administration is of great significance. The purpose of present study was to develop a long-term sustained-released in situ gel of a water-insoluble drug AMB for mycotic arthritis intra-articular administration. Based on the evaluations of the in vitro properties of the formulations, the formulation containing 10% (w/w) ethanol, 15% (w/w) PG, 0.75% (w/w) HA, 5% (w/w) purified soybean oil, 0.03% (w/w) α-tocopherol, 15% (w/w) water and 55% (w/w) glyceryl monooleate was selected as a suitable intra-articular injectable in situ gel drug delivery system for water-insoluble drug AMB. Furthermore, the results of the in vivo study on rabbits showed that the selected formulation was a safe and effective long-term sustained-released intra-articular injectable AMB preparation. Therefore, the presented in situ AMB gel could reduce the frequency of the administration in the AMB treatment of fungal arthritis, and then would get a good patient compliance.

  2. Hyperbranched polyglycerol-based lipids via oxyanionic polymerization: toward multifunctional stealth liposomes.

    PubMed

    Hofmann, Anna Maria; Wurm, Frederik; Hühn, Eva; Nawroth, Thomas; Langguth, Peter; Frey, Holger

    2010-03-08

    We describe the synthesis of linear-hyperbranched lipids for liposome preparation based on linear poly(ethylene glycol) (PEG) and hyperbranched polyglycerol (PG). Molecular weights were adjusted to values around 3000 g/mol with varying degrees of polymerization of the linear and the branched segments in analogy to PEG-based stealth lipids; polydispersities were generally low and below 1.3. The hydrophobic anchors were introduced into the lipid structures as initiators for the anionic polymerization of ethylene oxide and are either based on cholesterol or on different aliphatic glyceryl ethers. Complete incorporation of the apolar initiators was evidenced by MALDI-ToF analysis at all stages of the reaction. The linear-hyperbranched polyether lipid is incorporated as the polyfunctional shell in liposome formulations together with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC). The resulting liposomes were subsequently characterized via dynamic light scattering (DLS) and small angle neutron scattering (SANS) as well as transmission electron microscopy (TEM), demonstrating the formation of unilamellar liposomes in the size range of 40 to 50 nm.

  3. Novel process of fermenting black soybean [Glycine max (L.) Merrill] yogurt with dramatically reduced flatulence-causing oligosaccharides but enriched soy phytoalexins.

    PubMed

    Feng, Shengbao; Saw, Chin Lee; Lee, Yuan Kun; Huang, Dejian

    2008-11-12

    Black soybeans [Glycine max (L.) Merrill] were germinated under fungal stress with food grade R. oligosporus for 3 days and were homogenized and fermented with lactic acid bacteria (LAB) to produce soy yogurt. Fungal stress led to the generation of oxylipins [oxooctadecadienoic acids (KODES) isomers and their respective glyceryl esters] and glyceollins--a type of phytoalexins unique to soybeans. In soy yogurt, the concentrations of total KODES and total glyceollins were 0.678 mg/g (dry matter) and 0.953 mg/g, respectively. The concentrations of other isoflavones (mainly genistein and daidzein and their derivatives) in soy yogurt remained largely unchanged after the processes compared with the control soy yogurt. Germination of black soybean under fungal stress for 3 days was sufficient to reduce stachyose and raffinose (which cause flatulence) by 92 and 80%, respectively. With a pH value of 4.42, a lactic acid content of 0.262%, and a maximum viable cell count of 2.1 x 10 (8) CFU/mL in the final soy yogurt, soy milk from germinated soybeans under fungal stress was concluded to be a suitable medium for yogurt-making. The resulting soy yogurt had significantly altered micronutrient profiles with significantly reduced oligosaccharides and enriched glyceollins.

  4. Sensitivity analysis of near-infrared functional lymphatic imaging

    PubMed Central

    Weiler, Michael; Kassis, Timothy

    2012-01-01

    Abstract. Near-infrared imaging of lymphatic drainage of injected indocyanine green (ICG) has emerged as a new technology for clinical imaging of lymphatic architecture and quantification of vessel function, yet the imaging capabilities of this approach have yet to be quantitatively characterized. We seek to quantify its capabilities as a diagnostic tool for lymphatic disease. Imaging is performed in a tissue phantom for sensitivity analysis and in hairless rats for in vivo testing. To demonstrate the efficacy of this imaging approach to quantifying immediate functional changes in lymphatics, we investigate the effects of a topically applied nitric oxide (NO) donor glyceryl trinitrate ointment. Premixing ICG with albumin induces greater fluorescence intensity, with the ideal concentration being 150  μg/mL ICG and 60  g/L albumin. ICG fluorescence can be detected at a concentration of 150  μg/mL as deep as 6 mm with our system, but spatial resolution deteriorates below 3 mm, skewing measurements of vessel geometry. NO treatment slows lymphatic transport, which is reflected in increased transport time, reduced packet frequency, reduced packet velocity, and reduced effective contraction length. NIR imaging may be an alternative to invasive procedures measuring lymphatic function in vivo in real time. PMID:22734775

  5. A new class of furoxan derivatives as NO donors: mechanism of action and biological activity.

    PubMed Central

    Ferioli, R; Folco, G C; Ferretti, C; Gasco, A M; Medana, C; Fruttero, R; Civelli, M; Gasco, A

    1995-01-01

    1. The mechanism of action and biological activity of a series of R-substituted and di-R-substituted phenylfuroxans is reported. 2. Maximal potency as vasodilators on rabbit aortic rings, precontracted with noradrenaline (1 microM), was shown by phenyl-cyano isomers and by the 3,4-dicyanofuroxan, characterized by a potency ratio 3-10 fold higher than glyceryl trinitrate (GTN). This effect was reduced upon coincubation with methylene blue or oxyhaemoglobin (10 microM). 3. The furoxan derivatives showing maximal potency as vasodilators were also able to inhibit collagen-induced platelet aggregation, with IC50 values in the sub-micromolar range. 4. The furoxan derivatives were able to stimulate partially purified, rat lung soluble guanylate cyclase; among the most active compounds, the 3-R-substituted isomers displayed a higher level of stimulatory effect than the 4-R analogues. 5. Solutions (0.1 mM) of all the tested furoxans, prepared using 50 mM phosphate buffer, pH 7.4, (diluting 10 mM DMSO stock solutions) did not release nitric oxide (NO) spontaneously; however in presence of 5 mM L-cysteine, a significant NO-releasing capacity was observed, which correlated significantly with their stimulation of the guanylate cyclase activity. PMID:7773542

  6. Synthesis and characterization of novel polymers from non-petroleum sources for use in enhanced oil recovery. Final report, July 1, 1983-June 30, 1984

    SciTech Connect

    Hogen-Esch, T.E.

    1984-01-01

    Accomplishments for the past year are discussed for grafting of acrylamide to: (1) starch and related polysaccharides; and (2) cellulose solutions. In grafting acrylamide to various polysaccharide substrates such as okra polysaccharide, yellow dextrin, waxy corn starch, potato amylose, gum arabic, the efficiency of Ce/sup 4 +/ as initiator was found to vary from 0.02 to 0.89, depending on reaction conditions. Okra polysaccharide was isolated, characterized, and evaluated for use in enhanced oil recovery. A series of experiments designed to increase the viscosifying power of certain polymers by chain extension techniques has also been conducted. Characterization of the polymers by ultracentrifugation, size exclusion chromatography, membrane filtration, multi-cell equilibrium dialysis, and rheological studies has also been done. In grafting of acrylamide to cellulose solutions the following two courses were taken: (1) dissolution of cellulose in 70% aqueous zinc chloride, followed by Ce/sup 4 +/ initiated grafting of acrylamide, and (2) introduction of a 1,2-diol substituent onto the anhydroglucose units of the cellulose chain via dissolution of cellulose in concentrated aqueous NaOH, followed by treatment with glyceryl chlorohydrin. Considerable progress has been made via both approaches. 11 refs., 1 fig., 1 tab.

  7. Wax-incorporated emulsion gel beads of calcium pectinate for intragastric floating drug delivery.

    PubMed

    Sriamornsak, Pornsak; Asavapichayont, Panida; Nunthanid, Jurairat; Luangtana-Anan, Manee; Limmatvapirat, Sontaya; Piriyaprasarth, Suchada

    2008-01-01

    The purpose of this study was to prepare wax-incorporated pectin-based emulsion gel beads using a modified emulsion-gelation method. The waxes in pectin-olive oil mixtures containing a model drug, metronidazole, were hot-melted, homogenized and then extruded into calcium chloride solution. The beads formed were separated, washed with distilled water and dried for 12 h. The influence of various types and amounts of wax on floating and drug release behavior of emulsion gel beads of calcium pectinate was investigated. The drug-loaded gel beads were found to float on simulated gastric fluid if the sufficient amount of oil was used. Incorporation of wax into the emulsion gel beads affected the drug release. Water-soluble wax (i.e. polyethylene glycol) increased the drug release while other water-insoluble waxes (i.e. glyceryl monostearate, stearyl alcohol, carnauba wax, spermaceti wax and white wax) significantly retarded the drug release. Different waxes had a slight effect on the drug release. However, the increased amount of incorporated wax in the formulations significantly sustained the drug release while the beads remained floating. The results suggest that wax-incorporated emulsion gel beads could be used as a carrier for intragastric floating drug delivery.

  8. The enigma of nitroglycerin bioactivation and nitrate tolerance: news, views and troubles.

    PubMed

    Mayer, B; Beretta, M

    2008-09-01

    Nitroglycerin (glyceryl trinitrate; GTN) is the most prominent representative of the organic nitrates or nitrovasodilators, a class of compounds that have been used clinically since the late nineteenth century for the treatment of coronary artery disease (angina pectoris), congestive heart failure and myocardial infarction. Medline lists more than 15 000 publications on GTN and other organic nitrates, but the mode of action of these drugs is still largely a mystery. In the first part of this article, we give an overview on the molecular mechanisms of GTN biotransformation resulting in vascular cyclic GMP accumulation and vasodilation with focus on the role of mitochondrial aldehyde dehydrogenase (ALDH2) and the link between the ALDH2 reaction and activation of vascular soluble guanylate cyclase (sGC). In particular, we address the identity of the bioactive species that activates sGC and the potential involvement of nitrite as an intermediate, describe our recent findings suggesting that ALDH2 catalyses direct 3-electron reduction of GTN to NO and discuss possible reaction mechanisms. In the second part, we discuss contingent processes leading to markedly reduced sensitivity of blood vessels to GTN, referred to as vascular nitrate tolerance. Again, we focus on ALDH2 and describe the current controversy on the role of ALDH2 inactivation in tolerance development. Finally, we emphasize some of the most intriguing, in our opinion, unresolved puzzles of GTN pharmacology that urgently need to be addressed in future studies.

  9. Preparation and characterization of azithromycin--Aerosil 200 solid dispersions with enhanced physical stability.

    PubMed

    Li, Xuechao; Peng, Huanhuan; Tian, Bin; Gou, Jingxin; Yao, Qing; Tao, Xiaoguang; He, Haibing; Zhang, Yu; Tang, Xing; Cai, Cuifang

    2015-01-01

    The main purpose of this study was to investigate the feasibility of azithromycin (AZI)--Aerosil 200 solid dispersions specifically with high stability under accelerated condition (40 °C/75% RH). Ball milling (BM) and hot-melt extrusion (HME) were used to prepare AZI solid dispersions. The physical properties of solid dispersions were evaluated by differential scanning calorimetry (DSC), scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). For solid dispersions prepared with both methods, no crystalline of AZI was detected (except for AZI: Aerosil 200=75:25) by DSC or PXRD, indicating the amorphous state of AZI in solid dispersions. The FT-IR results demonstrated the loss of crystallization water and the formation of hydrogen bonds between Aerosil 200 and AZI during the preparation of solid dispersions. After 4 weeks storage under accelerated condition, the degree of crystallinity of AZI increased in solid dispersions prepared by BM, whereas for solid dispersions containing AZI, Aerosil 200 and glyceryl behenate (GB) prepared by HME, no crystalline of AZI was identified. This high stability can be attributed to the hydrophobic properties of GB and the presence of hydrogen bonds. Based on the above results, it is inferred the protection of hydrogen bonds between AZI and Aerosil 200 formed during preparation process effectively inhibited the recrystallization of AZI and improved the physical stability of amorphous AZI in the presence of Aerosil 200.

  10. Hydrophilic diol monolith for the preparation of immuno-sorbents at reduced nonspecific interactions.

    PubMed

    Gunasena, Dilani N; El Rassi, Ziad

    2011-08-01

    A polar organic polymer monolith (M1) was introduced for performing immunoaffinity chromatography (IAC) at reduced nonspecific interactions. The M1 monolith was prepared by the in situ polymerization of glyceryl methacrylate (GMM) and pentaerythritol triacrylate (PETA). Through its surface diol groups, M1 provided the functionalities to immobilize antibodies. Anti-haptoglobin antibody was used as the model antibody to study the overall behavior of the immuno monolith M1 in terms of its binding to the antigen and to evaluate its nonspecific binding with other proteins, especially the high-abundance human serum proteins. To better assess the suitability of M1 for IAC, other immuno monoliths were prepared and compared with the immuno monolith M1. Two monoliths were of the traditional ones: copolymers of (i) glycidyl methacrylate and ethylene glycol dimethacrylate (EDMA) and (ii) GMM and EDMA, referred to as M2 and M3, respectively. A fourth monolith involving the copolymerization of N-(3-aminopropyl)methacrylamide hydrochloride and EDMA (M4) was introduced to allow the site-directed immobilization of antibodies. Owing to its hydroxyl groups, the M1 exhibited negligible nonspecific hydrophobic interactions with proteins. On the other hand, M4 exhibited extensive electrostatic interactions, while the M2 and to a lesser extent M3 exhibited hydrophobic interactions.

  11. Exercise-induced improvement in endothelial dysfunction is not mediated by changes in CV risk factors: pooled analysis of diverse patient populations.

    PubMed

    Green, Daniel J; Walsh, Jennifer H; Maiorana, Andrew; Best, Matthew J; Taylor, Roger R; O'Driscoll, J Gerard

    2003-12-01

    We have pooled data from a series of our exercise training studies undertaken in groups with a broad range of vascular (dys) function to the examine the hypothesis that exercise-induced improvements in the conduit and/or resistance vessel function are related to improvements in risk factors for cardiovascular (CV) disease. Endothelium-dependent and -independent conduit vessel function were assessed by using wall tracking of high-resolution ultrasound images of the brachial artery response to flow-mediated dilation (FMD) and glyceryl trinitrate. Resistance vessel function was assessed using intrabrachial administration of acetylcholine (ACh), sodium nitroprusside, and NG-monomethyl-l-arginine. Randomized cross-over studies of 8-wk exercise training were undertaken in untreated hypercholesterolemic (n = 11), treated hypercholesterolemic (n = 11), coronary artery disease (n = 10), chronic heart failure (n = 12), Type 2 diabetic (n = 15), and healthy control subjects (n = 16). Exercise training did not significantly alter plasma lipids, blood pressure, blood glucose, waist-to-hip ratio, or body mass index values, despite significant improvement in both FMD and ACh responses. There were no correlations between changes in any risk factor variables and indexes of either resistance or conduit vessel function. We conclude that, in these subjects with antecedent vascular dysfunction, the beneficial effects of relatively short-term exercise training on vascular function are not solely mediated by the effects of exercise on CV risk factors.

  12. Speciation of arsenic in marine food (Anemonia sulcata) by liquid chromatography coupled to inductively coupled plasma mass spectrometry and organic mass spectrometry.

    PubMed

    Contreras-Acuña, M; García-Barrera, T; García-Sevillano, M A; Gómez-Ariza, J L

    2013-03-22

    Arsenic species have been investigated in Anemonia sulcata, which is frequently consumed food staple in Spain battered in wheat flour and fried with olive oil. Speciation in tissue extracts was carried out by anion/cation exchange chromatography with inductively coupled plasma mass spectrometry (HPLC-(AEC/CEC)-ICP-MS). Three methods for the extraction of arsenic species were investigated (ultrasonic bath, ultrasonic probe and focused microwave) and the optimal one was applied. Arsenic speciation was carried out in raw and cooked anemone and the dominant species are dimethylarsinic acid (DMA(V)) followed by arsenobetaine (AB), As(V), monomethylarsonic acid (MA(V)), tetramethylarsonium ion (TETRA) and trimethylarsine oxide (TMAO). In addition, arsenocholine (AsC), glyceryl phosphorylarsenocholine (GPAsC) and dimethylarsinothioic acid (DMAS) were identified by liquid chromatography coupled to triple quadrupole mass spectrometry (HPLC-MS). These results are interesting since GPAsC has been previously reported in marine organisms after experimental exposure to AsC, but not in natural samples. In addition, this paper reports for the first time the identification of DMAS in marine food.

  13. Can migraine aura be provoked experimentally? A systematic review of potential methods for the provocation of migraine aura.

    PubMed

    Lindblad, Marianne; Hougaard, Anders; Amin, Faisal Mohammad; Ashina, Messoud

    2017-01-01

    Background The nature of the migraine aura and its role in migraine pathophysiology is incompletely understood. In particular, the mechanisms underlying aura initiation and the causal relation between aura and headache are unknown. The scientific investigation of aura in patients is only possible if aura can be triggered. This paper reviews potential methods for the experimental provocation of migraine aura. Methods We systematically searched PubMed for studies of experimental migraine provocation, including case reports of patients with aura and reports of the occurrence of aura following exposure to any kind of suspected trigger. Results We identified 21 provocation studies, using 13 different prospective provocation methods, and 34 case reports. In the prospective studies, aura were reported following the administration of intravenous and sublingual glyceryl trinitrate, visual stimulation, physical activity, calcitonin gene-related peptide infusion, chocolate ingestion, and the intravenous injection of insulin. In addition, carotid artery puncture has consistently been reported as a trigger of aura. Conclusions No safe and efficient method for aura provocation exists at present, but several approaches could prove useful for this purpose.

  14. Silica nanoparticle stabilization of liquid crystalline lipid dispersions: impact on enzymatic digestion and drug solubilization.

    PubMed

    Bhatt, Achal B; Barnes, Timothy J; Prestidge, Clive A

    2015-01-01

    The high internal surface area and drug solubilizing capacity of liquid crystal lipids makes them promising oral drug delivery systems. Pluronic F127 is typically used to disperse highly viscous cubic liquid crystal lipids into cubosomes; however, such copolymers alter the internal structure and provide little control over enzymatic digestion. This study aimed to use hydrophilic silica nanoparticles to stabilize glyceryl monooleate (GMO) cubosomes prepared by ultrasonication. We investigate the influence of silica nanoparticles size and concentration on the physical (colloidal) and chemical (enzymatic digestion) stability, as well as in vitro solubilization of cinnarizine as a poorly soluble model drug. Silica stabilized nanostructured liquid crystal dispersions (120 nm to150 nm in diameter and zeta potentials of-30 mV to -60 mV) were successfully prepared with excellent long-term stability (<10% size change after 30 days). Silica stabilized GMO cubosomes demonstrated reduced enzymatic digestion compared to pluronic F127 stabilized cubosomes. This reduced digestion was attributed to a combination of adsorbed silica nanoparticles acting as a physical barrier and excess dispersed silica adsorbing/scavenging the lipase enzyme. Under simulated intestinal digestion conditions, silica stabilized GMO cubosomes showed a greater solubilization capacity for cinnarizine, which precipitated in non-crystalline form, in comparison to pure drug suspensions or pluronic F127 stabilized GMO cubosomes. Silica nanoparticle stabilized GMO liquid crystal dispersions are a promising oral delivery vehicle.

  15. Evaluating the potential of cubosomal nanoparticles for oral delivery of amphotericin B in treating fungal infection.

    PubMed

    Yang, Zhiwen; Chen, Meiwan; Yang, Muhua; Chen, Jian; Fang, Weijun; Xu, Ping

    2014-01-01

    The oral administration of amphotericin B (AmB) has a major drawback of poor bioavailability. The aim of this study was to investigate the potential of glyceryl monoolein (GMO) cubosomes as lipid nanocarriers to improve the oral efficacy of AmB. Antifungal efficacy was determined in vivo in rats after oral administration, to investigate its therapeutic use. The human colon adenocarcinoma cell line (Caco-2) was used in vitro to evaluate transport across a model of the intestinal barrier. In vivo antifungal results showed that AmB, loaded in GMO cubosomes, could significantly enhance oral efficacy, compared against Fungizone, and that during a 2 day course of dosage 10 mg/kg the drug reached effective therapeutic concentrations in renal tissue for treating fungal infections. In the Caco-2 transport studies, GMO cubosomes resulted in a significantly larger amount of AmB being transported into Caco-2 cells, via both clathrin- and caveolae-mediated endocytosis, but not macropinocytosis. These results suggest that GMO cubosomes, as lipid nanovectors, could facilitate the oral delivery of AmB.

  16. Extension of the LOPLS-AA Force Field for Alcohols, Esters, and Monoolein Bilayers and its Validation by Neutron Scattering Experiments.

    PubMed

    Pluhackova, Kristyna; Morhenn, Humphrey; Lautner, Lisa; Lohstroh, Wiebke; Nemkovski, Kirill S; Unruh, Tobias; Böckmann, Rainer A

    2015-12-10

    The recently presented LOPLS-AA all-atom force field for long hydrocarbon chains, based on the OPLS-AA force field, was extended to alcohols, esters, and glyceryl monooleate (GMO) lipids as a model lipid. Dihedral angles were fitted against high level ab initio calculations, and ester charges were increased to improve their hydration properties. Additionally, the ester Lennard-Jones parameters were readjusted to reproduce experimental liquid bulk properties, densities, and heats of vaporization. This extension enabled the setup of LOPLS-AA parameters for GMO molecules. The properties of the lipid force field were tested for the liquid-crystalline phase of a GMO bilayer. The obtained area per lipid for GMO is in good agreement with experiment. Additionally, the lipid dynamics on the subpicosecond to the nanosecond time scale is in excellent agreement with results from time-of-flight (TOF) quasielastic neutron scattering (QENS) experiments on a multilamellar monoolein system, enabling here for the first time the critical evaluation of the short-time dynamics obtained from a molecular dynamics simulation of a membrane system.

  17. Angioplasty of forearm arteries as a finger salvage procedure for patient with end-stage renal failure

    PubMed Central

    Law, Yuk; Chan, Yiu Che; Cheng, Stephen Wing-Keung

    2016-01-01

    Due to the relatively low metabolic demand and extensive collaterals of the upper limb, peripheral arterial disease seldom leads to tissue loss, except in patients with end-stage renal failure (ESRF), rheumatologic diseases, Raynaud’s disease, frostbites, or distal emboli. We report a case of a 51-year-old lady with ESRF who presented to our tertiary referral vascular center with infected gangrene of her right ring finger. Duplex ultrasound showed that her forearm arteries were severely diseased. Digital subtraction angiogram showed severe multilevel stenoses/occlusions in her forearm radial and ulnar arteries. These lesions were successfully angioplastized with 2 mm × 25 mm angioplasty balloon. Completion angiogram showed good radiological results with some post-dilatation spasm which improved with intra-arterial glyceryl trinitrate. The sepsis improved after revascularization, and the distal phalanx was allowed to self-demarcate with dressings and autoamputate with good clinical results. Our case illustrated that even in delayed setting, patients could still benefit from specialist vascular care with a combination of expert care and angioplasty of forearm arteries, with successful salvage of her finger. PMID:27143949

  18. Lipids and the malarial parasite*

    PubMed Central

    Holz, George G.

    1977-01-01

    Merozoite endocytosis initiates Plasmodium development in a vacuole bounded by an erythrocyte-derived membrane, whose asymmetrical distribution of lipids and proteins is reversed in its orientation with respect to the parasite plasma membrane. Reorientation may accompany the proliferation of the membrane associated with the parasite's growth and phagocytic and pinocytic feeding. Increases in the membrane surface area of the parasite, and in some cases of the erythrocyte, parallel parasite growth and segmentation. Augmentation of all the membrane systems of the infected erythrocyte causes the lipid content to rise rapidly, but the parasite lipid composition differs from that of the erythrocyte in many respects: it is higher in diacyl phosphatidylethanolamine, phosphatidylinositol, polyglycerol phosphatides, diacylglycerols, unesterified fatty acids, triacylglycerols, and hexadecanoic and octadecenoic fatty acids and lower in sphingomyelin, phosphatidylserine, alkoxy phosphatidylethanolamine, cholesterol, and polyunsaturated fatty acids. Active lipid metabolism accompanies the membrane proliferation associated with feeding, growth, and reproduction. Plasmodium is incapable of de novo biosynthesis of fatty acids and cholesterol; however, it can fabricate its glycerides and phosphoglycerides with host-supplied fatty acids, nitrogenous bases, alcohols, ATP, and coenzyme A, and can generate the glyceryl moiety during glycolysis. Cholesterol is obtained from the host but nothing is known of sphingolipid origins. Lipid metabolism of the parasite may be associated with alterations in the amounts of octadecenoic fatty acids and cholesterol in the erythrocyte plasma membrane, which in turn are responsible for changes in permeability and fragility. PMID:412602

  19. Nanoscale confinement effects on the relaxation dynamics in networks of diglycidyl ether of bisphenol-A and low-molecular-weight poly(ethylene oxide).

    PubMed

    Kalogeras, Ioannis M; Stathopoulos, Andreas; Vassilikou-Dova, Aglaia; Brostow, Witold

    2007-03-22

    Thermoplastic poly(ethylene oxide) (PEO) (Mw(PEO) approximately 4000) has been used to prepare thermosetting nanocomposites incorporating diglycidyl ether of bisphenol A (DGEBA) epoxy oligomer. Blends with various PEO/DGEBA weight ratios were cured using stoichiometric portions of 4,4'-diaminodiphenylmethane. The resulting semi-interpenetrating polymer networks were studied by several techniques. Nanoscale confinement effects, thermal (glass transition, melting and crystallization temperatures) and structural features of our materials are similar to those for networks with much higher Mw(PEO) and different curing agents; however, the polyether crystallization onset occurs in our case at a lower PEO concentration; shorter PEO chains organize themselves more easily into crystalline domains. Very low estimates of the k parameter of the Gordon-Taylor equation, used to fit the compositional dependences of the dielectric and calorimetric glass transition temperatures, and a strong plasticization of the motion of the glyceryl segments (beta-relaxation) in the epoxy resin were observed. These illustrate an intensified weakening in the strength of the intermolecular interactions in the modified networks, as compared to the high strength of the self-association of hydroxyls in the neat resin. The significance of hydrogen-bonding interactions between the components for obtaining structurally homogeneous thermoset-i-thermoplastic networks is discussed.

  20. Integration of chemical catalysis with extractive fermentation to produce fuels.

    PubMed

    Anbarasan, Pazhamalai; Baer, Zachary C; Sreekumar, Sanil; Gross, Elad; Binder, Joseph B; Blanch, Harvey W; Clark, Douglas S; Toste, F Dean

    2012-11-08

    Nearly one hundred years ago, the fermentative production of acetone by Clostridium acetobutylicum provided a crucial alternative source of this solvent for manufacture of the explosive cordite. Today there is a resurgence of interest in solventogenic Clostridium species to produce n-butanol and ethanol for use as renewable alternative transportation fuels. Acetone, a product of acetone-n-butanol-ethanol (ABE) fermentation, harbours a nucleophilic α-carbon, which is amenable to C-C bond formation with the electrophilic alcohols produced in ABE fermentation. This functionality can be used to form higher-molecular-mass hydrocarbons similar to those found in current jet and diesel fuels. Here we describe the integration of biological and chemocatalytic routes to convert ABE fermentation products efficiently into ketones by a palladium-catalysed alkylation. Tuning of the reaction conditions permits the production of either petrol or jet and diesel precursors. Glyceryl tributyrate was used for the in situ selective extraction of both acetone and alcohols to enable the simple integration of ABE fermentation and chemical catalysis, while reducing the energy demand of the overall process. This process provides a means to selectively produce petrol, jet and diesel blend stocks from lignocellulosic and cane sugars at yields near their theoretical maxima.

  1. Maintenance Therapy with Partially Hydrolyzed Guar Gum in the Conservative Treatment of Chronic Anal Fissure: Results of a Prospective, Randomized Study

    PubMed Central

    Izzo, Giuseppe; Di Martino, Natale; Renzi, Adolfo

    2014-01-01

    Purpose. This study was designed to evaluate the role of maintenance therapy with partially hydrolyzed guar gum (PHGG) after topical application of glyceryl trinitrate (GTN) in the conservative treatment of chronic anal fissure (CAF). Methods. From all the patients with CAF observed during the study period, 165 subjects with healed CAF after standard therapy with topical GTN 0.4% ointment were randomized to receive (group II) or not (group I) maintenance therapy with PHGG for 10 months. Clinical and manometric followup was carried out 6 and 12 months after treatment. Results. At six-month followup, median visual analogue scale score was significantly higher in group I if compared with group II. The success and recurrence rate at 12-month followup were, respectively, 38.3% (28/73) in group I versus 58.5% (41/70) in group II (P = 0.019; Fisher's exact test) and 30.2% (13/43) in group I versus 14.5% (7/48) in group II (P = 0.0047; Fisher's exact test). Conclusion. The maintenance therapy with PHGG in patients with healed CAF after chemical sphincterotomy by topical application of GTN 0.4% ointment seems associated with a significant reduction of recurrence rate and with a significant increase of success rate at 12-month followup. PMID:25089280

  2. Supercritical carbon dioxide interpolymer complexes improve survival of B. longum Bb-46 in simulated gastrointestinal fluids.

    PubMed

    Thantsha, Mapitsi S; Cloete, Thomas E; Moolman, Francis S; Labuschagne, Philip W

    2009-01-31

    Gastric acidity is the main factor affecting viability of probiotics in the gastrointestinal tract (GIT). This study investigated the survival in simulated gastrointestinal fluids of Bifidobacterium longum Bb-46 encapsulated in interpolymer complexes formed in supercritical carbon dioxide (scCO(2)). Bacteria were exposed sequentially to simulated gastric fluid (SGF, pH 2) for 2 h and simulated intestinal fluid (SIF, pH 6.8) for 6 or 24 h. Total encapsulated bacteria were determined by suspending 1 g of product in SIF for 6 h at 37 degrees C prior to plating out. Plates were incubated anaerobically at 37 degrees C for 72 h. The interpolymer complex displayed pH-responsive release properties, with little to no release in SGF and substantial release in SIF. There was a limited reduction in viable counts at the end of exposure period due to encapsulation. Protection efficiency of the interpolymer complex was improved by addition of glyceryl monostearate (GMS). Gelatine capsules delayed release of bacteria from the interpolymer complex thus minimizing time of exposure to the detrimental conditions. Use of poly(caprolactone) (PCL), ethylene oxide-propylene oxide triblock copolymer (PEO-PPO-PEO) decreased the protection efficiency of the matrix. Interpolymer complex encapsulation showed potential for protection of probiotics and therefore for application in food and pharmaceuticals.

  3. Effect of Coating Method on the Survival Rate of L. plantarum for Chicken Feed

    PubMed Central

    Lee, Sang-Yoon; Jo, Yeon-Ji; Choi, Mi-Jung; Lee, Boo-Yong; Han, Jong-Kwon; Lim, Jae Kag

    2014-01-01

    This study was designed to find the most suitable method and wall material for microencapsulation of the Lactobacillus plantarum to maintain cell viability in different environmental conditions. To improve the stability of L. plantarum, we developed an encapsulation system of L. plantarum, using water-in-oil emulsion system. For the encapsulation of L. plantarum, corn starch and glyceryl monostearate were selected to form gel beads. Then 10% (w/v) of starch was gelatinized by autoclaving to transit gel state, and cooled down at 60ºC and mixed with L. plantarum to encapsulate it. The encapsulated L. plantarum was tested for the tolerance of acidic conditions at different temperatures to investigate the encapsulation ability. The study indicated that the survival rate of the microencapsulated cells in starch matrix was significantly higher than that of free cells in low pH conditions with relatively higher temperature. The results showed that corn starch as a wall material and glycerol monostearate as a gelling agent in encapsulation could play a role in the viability of lactic acid bacteria in extreme conditions. Using the current study, it would be possible to formulate a new water-in-oil system as applied in the protection of L. plantarum from the gastric conditions for the encapsulation system used in chicken feed industry. PMID:26760943

  4. Defensive Armor of Potato Tubers: Nonpolar Metabolite Profiling, Antioxidant Assessment, and Solid-State NMR Compositional Analysis of Suberin-Enriched Wound-Healing Tissues

    PubMed Central

    Dastmalchi, Keyvan; Kallash, Linda; Wang, Isabel; Phan, Van C.; Huang, Wenlin; Serra, Olga; Stark, Ruth E.

    2016-01-01

    The cultivation, storage, and distribution of potato tubers are compromised by mechanical damage and suboptimal healing. To investigate wound-healing progress in cultivars with contrasting russeting patterns, metabolite profiles reported previously for polar tissue extracts were complemented by GC/MS measurements for nonpolar extracts and quantitative 13C NMR of interfacial solid suspensions. Potential marker compounds that distinguish cultivar type and wound-healing time point included fatty acids, fatty alcohols, alkanes, glyceryl esters, α,ω-fatty diacids, and hydroxyfatty acids. The abundant long-chain fatty acids in nonpolar extracts and solids from the smooth-skinned Yukon Gold cultivar suggested extensive suberin biopolymer formation; this hypothesis was supported by high proportions of arenes, alkenes, and carbonyl groups in the solid and among the polar markers. The absence of many potential marker classes in nonpolar Atlantic extracts and interfacial solids suggested a limited extent of suberization. Modest scavenging activities of all nonpolar extracts indicate that the majority of antioxidants produced in response to wounding are polar. PMID:26166447

  5. Defensive Armor of Potato Tubers: Nonpolar Metabolite Profiling, Antioxidant Assessment, and Solid-State NMR Compositional Analysis of Suberin-Enriched Wound-Healing Tissues.

    PubMed

    Dastmalchi, Keyvan; Kallash, Linda; Wang, Isabel; Phan, Van C; Huang, Wenlin; Serra, Olga; Stark, Ruth E

    2015-08-05

    The cultivation, storage, and distribution of potato tubers are compromised by mechanical damage and suboptimal healing. To investigate wound-healing progress in cultivars with contrasting russeting patterns, metabolite profiles reported previously for polar tissue extracts were complemented by GC/MS measurements for nonpolar extracts and quantitative (13)C NMR of interfacial solid suspensions. Potential marker compounds that distinguish cultivar type and wound-healing time point included fatty acids, fatty alcohols, alkanes, glyceryl esters, α,ω-fatty diacids, and hydroxyfatty acids. The abundant long-chain fatty acids in nonpolar extracts and solids from the smooth-skinned Yukon Gold cultivar suggested extensive suberin biopolymer formation; this hypothesis was supported by high proportions of arenes, alkenes, and carbonyl groups in the solid and among the polar markers. The absence of many potential marker classes in nonpolar Atlantic extracts and interfacial solids suggested a limited extent of suberization. Modest scavenging activities of all nonpolar extracts indicate that the majority of antioxidants produced in response to wounding are polar.

  6. Delivery of Dual Drug Loaded Lipid Based Nanoparticles across the Blood-Brain Barrier Impart Enhanced Neuroprotection in a Rotenone Induced Mouse Model of Parkinson's Disease.

    PubMed

    Kundu, Paromita; Das, Manasi; Tripathy, Kalpalata; Sahoo, Sanjeeb K

    2016-12-21

    Parkinson's disease (PD) is the most widespread form of dementia where there is an age related degeneration of dopaminergic neurons in the substantia nigra region of the brain. Accumulation of α-synuclein (αS) protein aggregate, mitochondrial dysfunction, oxidative stress, and neuronal cell death are the pathological hallmarks of PD. In this context, amalgamation of curcumin and piperine having profound cognitive properties, and antioxidant activity seems beneficial. However, the blood-brain barrier (BBB) is the major impediment for delivery of neurotherapeutics to the brain. The present study involves formulation of curcumin and piperine coloaded glyceryl monooleate (GMO) nanoparticles coated with various surfactants with a view to enhance the bioavailability of curcumin and penetration of both drugs to the brain tissue crossing the BBB and to enhance the anti-parkinsonism effect of both drugs in a single platform. In vitro results demonstrated augmented inhibition of αS protein into oligomers and fibrils, reduced rotenone induced toxicity, oxidative stress, and apoptosis, and activation of autophagic pathway by dual drug loaded NPs compared to native counterpart. Further, in vivo studies revealed that our formulated dual drug loaded NPs were able to cross BBB, rescued the rotenone induced motor coordination impairment, and restrained dopaminergic neuronal degeneration in a PD mouse model.

  7. An oral controlled release system for ambroxol hydrochloride containing a wax and a water insoluble polymer.

    PubMed

    Chi, Na; Guo, Ju Hong; Zhang, Yu; Zhang, Wei; Tang, Xing

    2010-01-01

    This study was carried out to develop and optimize oral sustained-release formulations for Ambroxol hydrochloride matrix pellets using a combination of wax and water-insoluble polymer, glyceryl behenate (Compritol 888 ATO) and Ethylcellulose (EC(7 FP)). It involved three factors: the content of Compritol 888 ATO (X(1)), EC(7 FP) (X(2)), and the matrix formation methods (X(3)), as independent variables. The drug release percentages at 1, 2 and 4 h were the target responses and were restricted to 15-45% (Y(1)), 45-80% (Y(2)) and 80-100% (Y(3)), respectively. The final blend formulation prepared by extrusion spheronization, was achieved with 27.00% (w/w) Ambroxol hydrochloride, 48.70% (w/w) Compritol 888 ATO, and 24.30% (w/w) EC(7 Fp) with 40 degrees C for 12 h. Comparing the single matrix materials consisting of just the wax or water-insoluble in the complex matrix system containing wax and water-insoluble polymer, the release of the drug can be far more retarded, when the formulations have undergone the process of heat treatment. Furthermore, the combination of the two polymers, with flexible matrix formation methods, will offer a very promising way of producing matrix pellets instead of coated controlled-release pellets to meet various demands of drug release.

  8. Mono- and tri-ester hydrogenolysis using tandem catalysis. Scope and mechanism.

    SciTech Connect

    Lohr, Tracy L.; Li, Zhi; Assary, Rajeev S.; Curtiss, Larry A.; Marks, Tobin J.

    2016-01-01

    The scope and mechanism of thermodynamically leveraged ester RC(O)O-R' bond hydrogenolysis by tandem metal triflate + supported Pd catalysts are investigated both experimentally and theoretically by DFT and energy span analysis. This catalytic system has a broad scope, with relative cleavage rates scaling as, tertiary 4 secondary 4 primary ester at 1 bar H-2, yielding alkanes and carboxylic acids with high conversion and selectivity. Benzylic and allylic esters display the highest activity. The rate law is nu = k[M(OTf )(n)](1)[ester](0)[H-2](0) with an H/D kinetic isotope effect = 6.5 +/- 0.5, implying turnover-limiting C-H scission following C-O cleavage, in agreement with theory. Intermediate alkene products are then rapidly hydrogenated. Applying this approach with the very active Hf(OTf)(4) catalyst to bio-derived triglycerides affords near-quantitative yields of C-3 hydrocarbons rather than glycerol. From model substrates, it is found that RC(O)O-R' cleavage rates are very sensitive to steric congestion and metal triflate identity. For triglycerides, primary/external glyceryl CH2-O cleavage predominates over secondary/internal CH-O cleavage, with the latter favored by less acidic or smaller ionic radius metal triflates, raising the diester selectivity to as high as 48% with Ce(OTf)(3).

  9. Towards a versatile technique for tracking nanoparticle-mucus interaction: a step on the road

    NASA Astrophysics Data System (ADS)

    Nafee, N.; Schneider, M.

    2014-02-01

    Respiratory mucus is one of the main barriers for nanoparticle-based pulmonary delivery systems. This holds true especially for lung diseases like cystic fibrosis, where a very tenacious thick mucus layer hinders particle diffusion to the lung epithelium or the target area. Typically, mean square displacement of particles is used for mobility evaluation. In contrast, our objective is to develop a feasible technique to track directed particle penetration as a prerequisite for efficient pulmonary nanotherapy. Therefore, particle diffusion in artificial mucus was monitored based on confocal laser scanning microscopy (CLSM) and particle-mucus interaction was observed. As pharmaceutical relevant and benign materials, solid lipid nanoparticles (SLNs) were prepared by hot-melt emulsification using glyceryl behenate and different stabilizing agents such as poloxamer-407, tween-80, and polyvinyl alcohol (PVA). The diffusion of labeled SLNs in stained artificial sputum representing CF-patient sputum was verified by 3D time laps imaging. Thus, the effect of coating, particle size and mucus viscosity on nanoparticle diffusion was studied. Using image analysis software "Image J", the total fluorescent signal after 30 min in case of poloxamer-coated SLNs was 5 and 100 folds higher than tween- and PVA-coated SLNs, respectively. Nevertheless, increasing mucus viscosity reduced the diffusion of tweencoated SLNs by a factor of 10. Studying particle-mucus interaction by CLSM can be considered a promising and versatile technique.

  10. Perhydrolase-nanotube paint composites with sporicidal and antiviral activity.

    PubMed

    Grover, Navdeep; Douaisi, Marc P; Borkar, Indrakant V; Lee, Lillian; Dinu, Cerasela Zoica; Kane, Ravi S; Dordick, Jonathan S

    2013-10-01

    AcT (perhydrolase) containing paint composites were prepared leading to broad-spectrum decontamination. AcT was immobilized onto multi-walled carbon nanotubes (MWNTs) and then incorporated into latex-based paints to form catalytic coatings. These AcT-based paint composites showed a 6-log reduction in the viability of spores of Bacillus cereus and Bacillus anthracis (Sterne) within 60 min. The paint composites also showed >4-log reduction in the titer of influenza virus (X-31) within 10 min (initially challenged with 10(7) PFU/mL). AcT-based paint composites were also tested using various perhydrolase acyl donor substrates, including propylene glycol diacetate (PGD), glyceryl triacetate, and ethyl acetate, with PGD observed to be the best among the substrates tested for generation of peracetic acid and killing of bacillus spores. The operational stability of paint composites was also studied at different relative humidities and temperatures to simulate real-life operation.

  11. A monolithic lipase reactor for biodiesel production by transesterification of triacylglycerides into fatty acid methyl esters.

    PubMed

    Urban, Jiri; Svec, Frantisek; Fréchet, Jean M J

    2012-02-01

    An enzymatic reactor with lipase immobilized on a monolithic polymer support has been prepared and used to catalyze the transesterification of triacylglycerides into the fatty acid methyl esters commonly used for biodiesel. A design of experiments procedure was used to optimize the monolithic reactor with variables including control of the surface polarity of the monolith via variations in the length of the hydrocarbon chain in alkyl methacrylate monomer, time of grafting of 1-vinyl-4,4-dimethylazlactone used to activate the monolith, and time used for the immobilization of porcine lipase. Optimal conditions involved the use of a poly(stearyl methacrylate-co-ethylene dimethacrylate) monolith, grafted first with vinylazlactone, then treated with lipase for 2 h to carry out the immobilization of the enzyme. Best conditions for the transesterification of glyceryl tributyrate included a temperature of 37°C and a 10 min residence time of the substrate in the bioreactor. The reactor did not lose its activity even after pumping through it a solution of substrate equaling 1,000 reactor volumes. This enzymatic reactor was also used for the transesterification of triacylglycerides from soybean oil to fatty acid methyl esters thus demonstrating the ability of the reactor to produce biodiesel.

  12. Randomized controlled trial using bosentan to enhance the impact of exercise training in subjects with type 2 diabetes mellitus.

    PubMed

    Schreuder, Tim H A; Duncker, Dirk J; Hopman, Maria T E; Thijssen, Dick H J

    2014-11-01

    In type 2 diabetes patients, endothelin (ET) receptor blockade may enhance blood flow responses to exercise training. The combination of exercise training and ET receptor blockade may represent a more potent stimulus than training alone to improve vascular function, physical fitness and glucose homeostasis. We assessed the effect of an 8 week exercise training programme combined with either ET blockade or placebo on vasculature, fitness and glucose homeostasis in people with type 2 diabetes. In a double-blind randomized controlled trial, brachial endothelium-dependent and ‑independent dilatation (using flow-mediated dilatation and glyceryl trinitrate, respectively), glucose homeostasis (using Homeostasis Model Assessment for Insulin Resistance (HOMA-IR)) and physical fitness (maximal cycling test) were assessed in 18 men with type 2 diabetes (60 ± 6 years old). Subjects underwent an 8 week exercise training programme, with half of the subjects receiving ET receptor blockade (bosentan) and the other half a placebo, followed by reassessment of the tests above. Exercise training improved physical fitness to a similar extent in both groups, but we did not detect changes in vascular function in either group. This study suggests that there is no adaptation in brachial and femoral artery endothelial function after 8 weeks of training in type 2 diabetes patients. Endothelin receptor blockade combined with exercise training does not additionally alter conduit artery endothelial function or physical fitness in type 2 diabetes.

  13. Sensitivity analysis of near-infrared functional lymphatic imaging

    NASA Astrophysics Data System (ADS)

    Weiler, Michael; Kassis, Timothy; Dixon, J. Brandon

    2012-06-01

    Near-infrared imaging of lymphatic drainage of injected indocyanine green (ICG) has emerged as a new technology for clinical imaging of lymphatic architecture and quantification of vessel function, yet the imaging capabilities of this approach have yet to be quantitatively characterized. We seek to quantify its capabilities as a diagnostic tool for lymphatic disease. Imaging is performed in a tissue phantom for sensitivity analysis and in hairless rats for in vivo testing. To demonstrate the efficacy of this imaging approach to quantifying immediate functional changes in lymphatics, we investigate the effects of a topically applied nitric oxide (NO) donor glyceryl trinitrate ointment. Premixing ICG with albumin induces greater fluorescence intensity, with the ideal concentration being 150 μg/mL ICG and 60 g/L albumin. ICG fluorescence can be detected at a concentration of 150 μg/mL as deep as 6 mm with our system, but spatial resolution deteriorates below 3 mm, skewing measurements of vessel geometry. NO treatment slows lymphatic transport, which is reflected in increased transport time, reduced packet frequency, reduced packet velocity, and reduced effective contraction length. NIR imaging may be an alternative to invasive procedures measuring lymphatic function in vivo in real time.

  14. Risk based approach for design and optimization of stomach specific delivery of rifampicin.

    PubMed

    Vora, Chintan; Patadia, Riddhish; Mittal, Karan; Mashru, Rajashree

    2013-10-15

    The research envisaged focuses on risk management approach for better recognizing the risks, ways to mitigate them and propose a control strategy for the development of rifampicin gastroretentive tablets. Risk assessment using failure mode and effects analysis (FMEA) was done to depict the effects of specific failure modes related to respective formulation/process variable. A Box-Behnken design was used to investigate the effect of amount of sodium bicarbonate (X1), pore former HPMC (X2) and glyceryl behenate (X3) on percent drug release at 1st hour (Q1), 4th hour (Q4), 8th hour (Q8) and floating lag time (min). Main effects and interaction plots were generated to study effects of variables. Selection of the optimized formulation was done using desirability function and overlay contour plots. The optimized formulation exhibited Q1 of 20.9%, Q4 of 59.1%, Q8 of 94.8% and floating lag time of 4.0 min. Akaike information criteria and Model selection criteria revealed that the model was best described by Korsmeyer-Peppas power law. The residual plots demonstrated no existence of non-normality, skewness or outliers. The composite desirability for optimized formulation computed using equations and software were 0.84 and 0.86 respectively. FTIR, DSC and PXRD studies ruled out drug polymer interaction due to thermal treatment.

  15. Adrenoceptor hyporeactivity is responsible for Escherichia coli endotoxin-induced acute vascular dysfunction in humans.

    PubMed

    Pleiner, Johannes; Heere-Ress, Elisabeth; Langenberger, Herbert; Sieder, Anna E; Bayerle-Eder, Michaela; Mittermayer, Fritz; Fuchsjäger-Mayrl, Gabriele; Böhm, Johannes; Jansen, Burkhard; Wolzt, Michael

    2002-01-01

    Impaired response to catecholamines contributes to the altered hemodynamics in sepsis, which has been attributed to excessive NO formation. We have studied the systemic hemodynamic and local forearm responses and inducible NO synthase (iNOS) expression during experimental endotoxemia in humans. Escherichia coli endotoxin (lipopolysaccharide [LPS]) was administered at doses of 1 or 2 ng/kg to healthy volunteers. In 10 subjects, the systemic pressor effect of phenylephrine was assessed before and after the administration of LPS. In 9 further subjects, forearm blood flow responses to intra-arterial noradrenaline, acetylcholine, glyceryl trinitrate, and N(G)-monomethyl-L-arginine (L-NMMA) were studied at baseline and after LPS administration. Peripheral blood was collected and analyzed for iNOS mRNA and protein. Four hours after LPS, the response of systolic blood pressure (P<0.0005) and heart rate (P<0.05) to phenylephrine was significantly reduced. In the forearm, noradrenaline-induced vasoconstriction was also reduced by approximately 50% (P<0.01), but L-NMMA responsiveness was unchanged. iNOS mRNA or protein was not increased. Marked vascular adrenoceptor hyporeactivity is detectable in the absence of increased NO activity or iNOS expression in endotoxemia, arguing against major involvement of vascular iNOS activity in the acute systemic vasodilation to LPS.

  16. Curcumin nanoemulsion for transdermal application: formulation and evaluation.

    PubMed

    Rachmawati, Heni; Budiputra, Dewa Ken; Mauludin, Rachmat

    2015-04-01

    The aim of this work is to develop a curcumin nanoemulsion for transdermal delivery. The incorporation of curcumin inside a nanoglobul should improve curcumin stability and permeability. A nanoemulsion was prepared by the self-nanoemulsification method, using an oil phase of glyceryl monooleate, Cremophor RH40 and polyethylene glycol 400. Evaluation of the nanoemulsion included analysis of particle size, polydispersity index, zeta potential, physical stability, Raman spectrum and morphology. In addition, the physical performance of the nanoemulsion in Viscolam AT 100P gel was studied. A modified vertical diffusion cell and shed snake skin of Python reticulatus were used to study the in vitro permeation of curcumin. A spontaneously formed stable nanoemulsion has a loading capacity of 350 mg curcumin/10 g of oil phase. The mean droplet diameter, polydispersity index and zeta potential of optimized nanoemulsion were 85.0 ± 1.5 nm, 0.18 ± 0.0 and -5.9 ± 0.3 mV, respectively. Curcumin in a nanoemulsion was more stable than unencapsulated curcumin. Furthermore, nanoemulsification significantly improved the permeation flux of curcumin from the hydrophilic matrix gel; the release kinetic of curcumin changed from zero order to a Higuchi release profile. Overall, the developed nanoemulsion system not only improved curcumin permeability but also protected the curcumin from chemical degradation.

  17. Biodiesel synthesis using calcined layered double hydroxide catalysts

    SciTech Connect

    Schumaker, J. Link; Crofcheck, Czarena; TAckett, S. Adam; Santillan-Jimenez, Eduardo; Morgan, Tonya; Ji, Yaying; Crocker, Mark; Toops, Todd J

    2008-01-01

    The catalytic properties of calcined Li-Al, Mg-Al and Mg-Fe layered double hydroxides (LDHs) were examined in two transesterification reactions, namely, the reaction of glyceryl tributyrate with methanol, and the reaction of soybean oil with methanol. While the Li-Al catalysts showed high activity in these reactions at the reflux temperature of methanol, the Mg-Fe and Mg-Al catalysts exhibited much lower methyl ester yields. CO2 TPD measurements revealed the presence of sites of weak, medium and strong basicity on both Mg-Al and Li-Al catalysts, the latter showing higher concentrations of medium and strong base sites; by implication, these are the main sites active in transesterification catalyzed by calcined Li-Al LDHs. Maximum activity was observed for the Li-Al catalysts when a calcination temperature of 450-500 aC was applied, corresponding to decomposition of the layered double hydroxide to the mixed oxide without formation of crystalline lithium aluminate phases.

  18. Tricaprylin-water partition coefficients and their temperature dependence for selected chlorobenzenes

    SciTech Connect

    Bahadur, N.P.; Shiu, W.Y.; Boocock, D.G.B.; Mackay, D.

    1999-01-01

    Measurements of partition coefficients between tricaprylin (glyceryl tri-n-octanoate) and water are reported for seven chlorobenzenes (1,2-dichlorobenzene, 1,4-dichlorobenzene, 1,3,5-trichlorobenzene, 1,2,3,4-tetrachlorobenzene, 1,2,3,5-tetrachlorobenzene, pentachlorobenzene, and hexachlorobenzene) between 5 and 45 C. The values are compared with reported data on octanol-water and triolein-water partition coefficients. The van`t Hoff plots of log K{sub OW} versus T{sup {minus}1} exhibit linearity with values of K{sub OW} increasing by 5--8% over this temperature range, and the enthalpy of phase change varies from 9.7 to 16 kJ/mol. Several reasons are suggested why tricaprylin-water partition coefficients may be preferable to octanol-water and triolein-water partition coefficients when quantifying a substance`s hydrophobicity. The mutual solubilities of tricaprylin and water are less than that of octanol and water. Tricaprylin is easier to purify than triolein and, because of its lower molecular mass, is easier to analyze by gas chromatography.

  19. Paclitaxel loaded PEGylated gleceryl monooleate based nanoparticulate carriers in chemotherapy.

    PubMed

    Jain, Vikas; Swarnakar, Nitin K; Mishra, Prabhat R; Verma, Ashwni; Kaul, Ankur; Mishra, Anil K; Jain, Narendra K

    2012-10-01

    A PEGylated drug delivery system of paclitaxel (PTX), based on glyceryl monooleate (GMO) was prepared by optimizing various parameters to explore its potential in anticancer therapy. The prepared system was characterized through polarized light microscopy, TEM, AFM and SAXS to reveal its liquid crystalline nature. As GMO based LCNPs exhibit high hemolytic toxicity and faster release of entrapped drug (66.2 ± 2.5% in 24 h), PEGylation strategy was utilized to increase the hemocompatibility (reduction in hemolysis from 60.3 ± 10.2 to 4.4 ± 1.3%) and control the release of PTX (43.6 ± 3.2% released in 24 h). The cytotoxic potential and cellular uptake was assessed in MCF-7 cell lines. Further, biodistribution studies were carried out in EAT (Ehrlich Ascites tumor) bearing mice using (99m)Tc-(Technetium radionuclide) labeled formulations and an enhanced circulation time and tumor accumulation (14 and 8 times, respectively) were observed with PEGylated carriers over plain ones, at 24 h. Finally, tumor growth inhibition experiment was performed and after 15 days, control group exhibited 15 times enhancement in tumor volume, while plain and PEGylated systems exhibited only 8 and 4 times enhancement, respectively, as compared to initial tumor volume. The results suggest that PEGylation enhances the hemocompatibility and efficacy of GMO based system that may serve as an efficient i.v. delivery vehicle for paclitaxel.

  20. A theoretical approach to evaluate the release rate of acetaminophen from erosive wax matrix dosage forms.

    PubMed

    Agata, Yasuyoshi; Iwao, Yasunori; Shiino, Kai; Miyagishima, Atsuo; Itai, Shigeru

    2011-07-29

    To predict drug dissolution and understand the mechanisms of drug release from wax matrix dosage forms containing glyceryl monostearate (GM; a wax base), aminoalkyl methacrylate copolymer E (AMCE; a pH-dependent functional polymer), and acetaminophen (APAP; a model drug), we tried to derive a novel mathematical model with respect to erosion and diffusion theory. Our model exhibited good agreement with the whole set of experimentally obtained values pertaining to APAP release at pH 4.0 and pH 6.5. In addition, this model revealed that the eroding speed of wax matrices was strongly influenced by the loading content of AMCE, but not that of APAP, and that the diffusion coefficient increased as APAP loading decreased and AMCE loading increased, thus directly defining the physicochemical properties of erosion and diffusion. Therefore, this model might prove a useful equation for the precise prediction of dissolution and for understanding the mechanisms of drug release from wax matrix dosage forms.

  1. Acetylglyceryl ether phosphorylcholine (AGEPC; platelet-activating factor)-induced stimulation of rabbit platelets: correlation between phosphatidic acid level, 45Ca2+ uptake, and (3H)serotonin secretion

    SciTech Connect

    Shukla, S.D.; Hanahan, D.J.

    1984-08-01

    When 32P-labeled rabbits platelet were incubated with 5 X 10(-10) M 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine (AGEPC), either in the presence or absence (0.1 mM EGTA) of added Ca2+, there was a three- to five-fold increase in the (32P)phosphatidic acid (PA) pool within 15 to 20 s. This event was followed by a gradual decrease in the (32P)PA level to near basal level in 5 min. AGEPC effected this change in (32P)PA in a characteristic dose- and time-dependent manner. Polar head group analogs of AGEPC, such as AGEDME and AGEMME, also effected an increase in PA labeling at levels comparable to those previously reported for their activity toward rabbit platelets. Other analogs, i.e., lysoGEPC and the enantiomer, sn-1-AGEPC, which are inactive toward rabbit platelets, also showed no effect on the level of (32P)PA. The finding that the PA level in rabbit platelets could be manipulated by the addition of AGEPC, without any added Ca2+, provided an excellent model system for establishing a correlation between the uptake of Ca2+, serotonin release, and PA level. Thus, PA must be regarded as a sensitive indicator of a reaction mechanism important to the platelet response to AGEPC, and could be the focal point in promoting calcium uptake during the stimulation process.

  2. Safranal-loaded solid lipid nanoparticles: evaluation of sunscreen and moisturizing potential for topical applications

    PubMed Central

    Khameneh, Bahman; Halimi, Vahid; Jaafari, Mahmoud Reza; Golmohammadzadeh, Shiva

    2015-01-01

    Objective(s): In the current study, sunscreen and moisturizing properties of solid lipid nanoparticle (SLN)-safranal formulations were evaluated. Materials and Methods: Series of SLN were prepared using glyceryl monostearate, Tween 80 and different amounts of safranal by high shear homogenization, and ultrasound and high-pressure homogenization (HPH) methods. SLN formulations were characterized for size, zeta potential, morphology, thermal properties, and encapsulation efficacy. The Sun Protection Factor (SPF) of the products was determined in vitro using transpore tape. The moisturizing activity of the products was also evaluated by corneometer. Results: The SPF of SLN-safranal formulations was increased when the amount of safranal increased. Mean particle size for all formulas was approximately 106 nm by probe sonication and 233 nm using HPH method. The encapsulation efficiency of safranal was around 70% for all SLN-safranal formulations. Conclusion: The results conclude that SLN-safranal formulations were found to be effective for topical delivery of safranal and succeeded in providing appropriate sunscreen properties. PMID:25810877

  3. Combinatorial study of ceramic tape-casting slurries.

    PubMed

    Liu, Zhifu; Wang, Yiling; Li, Yongxiang

    2012-03-12

    Ceramic tape-casting slurries are complex systems composed of ceramic powder, solvent, and a number of organic components. Conventionally, the development of ceramic tape-casting slurries is time-consuming and of low efficiency. In this work, combinatorial approaches were applied to screen the ethanol and ethyl-acetate binary solvent based slurry for ceramic green tape-casting. The combinatorial libraries were designed considering the variation of the amount of PVB (Poly vinyl-butyral) binder, polyethylene-400, and butyl-benzyl-phthalate plasticizers, and glyceryl triacetate dispersant. A parallel magnetic stirring process was used to make the combinatorial slurry library. The properties mapping of the slurry library was obtained by investigating the sedimentation and rheological characteristics of the slurries. The slurry composition was refined by scaling up the experiments and comparing the microstructure, mechanical property, and sintering behavior of green tapes made from the selected slurries. Finally, a kind of ethanol-ethyl acetate binary solvent based slurry system suitable for making X7R dielectric ceramic green tapes was achieved.

  4. Asymmetric lipid-polymer particles (LIPOMER) by modified nanoprecipitation: role of non-solvent composition.

    PubMed

    Jindal, Anil B; Devarajan, Padma V

    2015-07-15

    Asymmetric lipid polymer nanostructures (LIPOMER) comprising glyceryl monostearate (GMS) as lipid and Gantrez AN 119 (Gantrez) as polymer, revealed enhanced splenic accumulation. In the present paper, we attempt to explain the formation of asymmetric GMS LIPOMER using real time imaging. Particles were prepared by precipitation under static conditions using different non-solvent phase compositions. The process was video recorded and the videos converted to time elapsed images using the FFmpeg 0.10.2 software at 25 frames/sec. Non-solvent compositions comprising >30% of IPA/Acetone revealed significant stranding of the solvent phase and slower onset of precipitation(2-6s). At lower concentrations of IPA and acetone, and in non-solvent compositions comprising ethanol/water the stranding phenomenon was not evident. Further, rapid precipitation(<1 s) was evident. Nanoprecipitation based on the Marangoni effect is a result of diffusion stranding, interfacial turbulence, and mass transfer of solvent and non-solvent resulting in solute precipitation. Enhanced diffusion stranding favored by high interaction of GMS and Gantrez(low ΔPol), and the low solubility parameter(Δδtotal) and high mixing enthalpy(ΔHM) of GMS in IPA resulted in droplets with random shapes analogous to an amoeba with pseudopodia, which on precipitation formed asymmetric particles. Asymmetric particles could be readily designed through appropriate selection of solutes and non-solvent phase by modified nanoprecipitation.

  5. Effects of hexagonal boron nitride on dry compression mixture of Avicel DG and Starch 1500.

    PubMed

    Uğurlu, Timuçin; Halaçoğlu, Mekin Doğa

    2016-01-01

    The objective of this study was to investigate the lubrication properties of hexagonal boron nitride (HBN) on a (1:1) binary mixture of Avicel DG and Starch 1500 after using the dry granulation-slugging method and compare it with conventional lubricants, such as magnesium stearate (MGST), glyceryl behenate (COMP) and stearic acid (STAC). MGST is one of the most commonly used lubricants in the pharmaceutical industry. However, it has several adverse effects on tablet properties. In our current study, we employed various methods to eradicate the work hardening phenomenon in dry granulation, and used HBN as a new lubricant to overcome the adverse effects of other lubricants on tablet properties. HBN was found to be as effective as MGST and did not show any significant adverse effects on the crushing strength or work hardening. From the scanning electron microscope (SEM) images, it was concluded that HBN distributed better than MGST. As well as showing better distribution, HBN's effect on disintegration was the least pronounced. Semi-quantitative weight percent distribution of B and N elements in the tablets was obtained using EDS (energy dispersive spectroscopy). Based on atomic force microscope (AFM) surface roughness images, formulations prepared with 1% HBN showed better plastic character than those prepared with MGST.

  6. Compression parameters of hexagonal boron nitride on direct compression mixture of microcrystalline cellulose and modified starch.

    PubMed

    Halaçoğlu, Mekin Doğa; Uğurlu, Timuçin

    2015-01-01

    The objective of this study was to investigate the effects of conventional lubricants including a new candidate lubricant "hexagonal boron nitride (HBN)" on direct compression powders. Lubricants such as magnesium stearate (MGST), glyceryl behenate, stearic acid, talc and polyethylene glycol6000 were studied and tablets were manufactured on a single station instrumented tablet press. This study comprised the continuation of our previous one, so mixture of microcrystalline cellulose and modified starch was used as a master formula to evaluate effects of lubricants on pharmaceutical excipients that undergo complete plastic deformation without any fragmentation under compression pressure. Bulk and tapped densities, and Carr's index parameters were calculated for powders. Tensile strength, cohesion index, lower punch ejection force and lubricant effectiveness values were investigated for tablets. The deformation mechanisms of tablets were studied during compression from the Heckel plots with or without lubricant. MGST was found to be the most effective lubricant and HBN was found very close to it. HBN did not show a significant negative effect on the crushing strength and disintegration time of the tablets when we compared with MGST. Based on the Heckel plots at the level of 1%, formulation prepared with HBN showed the most pronounced plastic character.

  7. Giant papillary conjunctivitis.

    PubMed Central

    Donshik, P C

    1994-01-01

    Giant papillary conjunctivitis is a syndrome found frequently as a complication of contact lenses. Many variables can affect the onset and severity of the presenting signs and symptoms. Rigid gas permeable contact lenses appear to result in less severe signs and symptoms, with a longer time before the development of giant papillary conjunctivitis. Nonionic, low-water-content soft contact lenses tend to produce less severe signs and symptoms than ionic, low-water-content soft contact lenses. Enzymatic treatment appears to lessen the severity of signs and symptoms. The association of an allergy appears to play a role in the onset of the severity of the signs and symptoms but does not appear to affect the final ability of the individual to wear contact lenses. Using multiple treatment options, such as changing the polymer to a glyceryl methyl methacrylate or a rigid lens, or utilizing a soft lens on a frequent-replacement basis, can result in a success rate of over 90%. In individuals who still have a return of symptoms, the use of topical mast cell stabilizers or a nonsteroidal anti-inflammatory drug as an adjunctive therapy offers the added possibility of keeping these patients in contact lenses. Images FIGURE 1 FIGURE 2 FIGURE 3 FIGURE 4 FIGURE 5 FIGURE 6 FIGURE 7 FIGURE 11 A FIGURE 11 B FIGURE 11 C FIGURE 11 D PMID:7886881

  8. Simple complementary liquid chromatography and mass spectrometry approaches for the characterization of triacylglycerols in Pinus koraiensis seed oil.

    PubMed

    Acheampong, Akwasi; Leveque, Nathalie; Tchapla, Alain; Heron, Sylvie

    2011-08-05

    A new simple strategy to identify triacylglycerols (TAGs) in oils and fats was performed using on line coupling of non aqueous reversed phase chromatography-electrospray ionization-mass spectrometry (NARP-LC-ESI-MS(2)) with silver nitrate (AgNO(3)) as post-column additive, and chromatographic data (partition number information and both the graphs of log k vs. number of double bond (DBN) and carbon number (CN)). NARP liquid chromatography permitted to separate TAGs composed of Δ5 and Δ9 but not from Δ11 double bond location on alkyl chain of fatty acid residues. Silver cationization improved the sensitivity by a factor one hundred. MS(2) information gave unambiguously the nature of three fatty acid residues bonded to glyceryl backbone of TAGs while log k against DBN and CN curves discriminated between the same molecular mass TAG isomers (whose constitutive fatty acid residues are double bond position and configuration isomers). Combination of structural information given by MS with chromatographic retention laws led to the development of a general methodology for determination of the structure of TAGs in lipids. This methodology was applied to Pinus koraiensis seed oil for which some uncommon TAGs are present. It permitted the identification of 58 TAGs in this oil. The experimental proof of 29 uncommon TAGs as component of this oil is demonstrated. Among them 26 were minor constituents.

  9. Production and characterization of anisotropic particles from biodegradable materials.

    PubMed

    Romanski, Francis S; Winkler, Jennifer S; Riccobene, Ryan C; Tomassone, M Silvina

    2012-02-28

    In recent years, production and characterization of anisotropic particles has become of interest in a wide range of scientific fields including polymer chemistry, drug delivery, electronics, energy, and nanotechnology. In this work, we demonstrate a novel formulation for production of anisotropic particles via an internal phase separation of biodegradable components. Specifically, binary mixtures of biodegradable polymers poly(lactic-co-glycolic acid), polycaprolactone, and biodegradable lipid Precirol (glyceryl palmitostearate) were dissolved in dichloromethane, emulsified, and prepared into anisotropic particles using a modified solvent evaporation technique. During the slow evaporation process the components self-assembled into anisotropic particles with distinct morphologies. Polymer/polymer formulations resulted in compartmentalized anisotropic heterodimer particles, while polymer/lipid combinations yielded "ice cream cone" shaped particles. It was found that addition of certain active pharmaceuticals resulted in an altered, pox-like segregation at the particle surface of polymer/polymer formulations. The anisotropic nature of the particles was subsequently characterized using optical microscopy, scanning electron microscopy, zeta potential, electrophoresis, and X-ray diffraction. Successful formulations presented here may potentially be employed as multicompartmental drug carriers with staggered drug release rates or alternatively as a colloidal excipient for an arsenal of pharmaceutical applications.

  10. Optimization of metronidazole sustained-release films using D-optimal design.

    PubMed

    Peerapattana, Jomjai; Ngamsupsiri, Teeraphat; Cheucharoenvasuchai, Nopadol; Saikaew, Charnnarong

    2015-04-30

    The aim of this study was to develop sustained-release metronidazole films for periodontal pockets using a computer-aided statistical approach. The studied independent variables were the amount of polycaprolactone, metronidazole, hydroxypropylmethyl cellulose and glyceryl monostearate. The response of interest was the cumulative percentage release of metronidazole at 1, 2, 3, 4 and 5 days. The films were prepared using a melt method. The physicochemical properties and release profiles of the films were investigated. Model validation was also performed. The produced films were thin white sheets with a smooth and glossy surface. Each sheet had an average weight of 9.31 ± 0.10mg. The metronidazole was uniformly dispersed in the film, and the percentage of drug loading was 100.12 ± 4.38%. The thickness of the film was 325 ± 5.27 μm. The puncture strength, % elongation and Young's modulus were 11.58 ± 0.51 N/mm(2), 33.51 ± 3.61%, and 0.347 ± 0.02 1N/mm(2), respectively. The actual drug release profiles of the optimal formulation films were close to the predicted responses. Metronidazole was slowly released from the matrices over a period of at least 5 days. The release mechanism of the films followed Fickian diffusion. This study demonstrates that appropriate D-optimal design and optimization techniques can be successfully used in the development of metronidazole sustained-release films.

  11. Nonequilibrium effects in self-assembled mesophase materials: unexpected supercooling effects for cubosomes and hexosomes.

    PubMed

    Dong, Yao-Da; Tilley, Adam J; Larson, Ian; Lawrence, M Jayne; Amenitsch, Heinz; Rappolt, Michael; Hanley, Tracey; Boyd, Ben J

    2010-06-01

    Polar lipids often exhibit equilibrium liquid crystalline structures in excess water, such as the bicontinuous cubic phases (Q(II)) at low temperatures and inverse hexagonal phase (H(II)) at higher temperatures. In this study, the equilibrium and nonequilibrium phase behavior of glyceryl monooleate (GMO) and phytantriol (PHYT) systems in excess water were investigated using both continuous heating and cooling cycles, and rapid temperature changes. Evolution of the phase structure was followed using small-angle X-ray scattering (SAXS). During cooling, not only was supercooling of the liquid crystalline systems by up to 25 degrees C observed, but evidence for nonequilibrium phase structures (not present on heating; such as the gyroid cubic phase only present at low water content in equilibrium) was also apparent. The nonequilibrium phases were surprisingly stable, with return to equilibrium structure for dispersed submicrometer sized particle systems taking more than 13 h in some cases. Inhibition of phase nucleation was the key to greater supercooling effects observed for the dispersed particles compared to the bulk systems. These findings highlight the need for continued study into the nonequilibrium phase structures for these types of systems, as this may influence performance in applications such as drug delivery.

  12. Rapid and sensitive measurements of nitrate ester explosives using microchip electrophoresis with electrochemical detection.

    PubMed

    Piccin, Evandro; Dossi, Nicolò; Cagan, Avi; Carrilho, Emanuel; Wang, Joseph

    2009-03-01

    This article describes an effective microchip protocol based on electrophoretic-separation and electrochemical detection for highly sensitive and rapid measurements of nitrate ester explosives, including ethylene glycol dinitrate (EGDN), pentaerythritol tetranitrate (PETN), propylene glycol dinitrate (PGDN) and glyceryl trinitrate (nitroglycerin, NG). Factors influencing the separation and detection processes were examined and optimized. Under the optimal separation conditions obtained using a 15 mM borate buffer (pH 9.2) containing 20 mM SDS, and applying a separation voltage of 1500 V, the four nitrate ester explosives were separated within less than 3 min. The glassy-carbon amperometric detector (operated at -0.9 V vs. Ag/AgCl) offers convenient cathodic detection down to the picogram level, with detection limits of 0.5 ppm and 0.3 ppm for PGDN and for NG, respectively, along with good repeatability (RSD of 1.8-2.3%; n = 6) and linearity (over the 10-60 ppm range). Such effective microchip operation offers great promise for field screening of nitrate ester explosives and for supporting various counter-terrorism surveillance activities.

  13. Effect of Coating Method on the Survival Rate of L. plantarum for Chicken Feed.

    PubMed

    Lee, Sang-Yoon; Jo, Yeon-Ji; Choi, Mi-Jung; Lee, Boo-Yong; Han, Jong-Kwon; Lim, Jae Kag; Oh, Jae-Wook

    2014-01-01

    This study was designed to find the most suitable method and wall material for microencapsulation of the Lactobacillus plantarum to maintain cell viability in different environmental conditions. To improve the stability of L. plantarum, we developed an encapsulation system of L. plantarum, using water-in-oil emulsion system. For the encapsulation of L. plantarum, corn starch and glyceryl monostearate were selected to form gel beads. Then 10% (w/v) of starch was gelatinized by autoclaving to transit gel state, and cooled down at 60ºC and mixed with L. plantarum to encapsulate it. The encapsulated L. plantarum was tested for the tolerance of acidic conditions at different temperatures to investigate the encapsulation ability. The study indicated that the survival rate of the microencapsulated cells in starch matrix was significantly higher than that of free cells in low pH conditions with relatively higher temperature. The results showed that corn starch as a wall material and glycerol monostearate as a gelling agent in encapsulation could play a role in the viability of lactic acid bacteria in extreme conditions. Using the current study, it would be possible to formulate a new water-in-oil system as applied in the protection of L. plantarum from the gastric conditions for the encapsulation system used in chicken feed industry.

  14. Local L-NG-monomethyl-arginine attenuates the vasodilator action of bradykinin in the human forearm.

    PubMed Central

    O'Kane, K P; Webb, D J; Collier, J G; Vallance, P J

    1994-01-01

    1. Studies in animals indicate that bradykinin relaxes blood vessels directly through an action on smooth muscle and indirectly through the release of endothelium-derived mediators. Its precise mechanism of action in the human arterial circulation is not yet known. 2. In this study the effects of a specific inhibitor of nitric oxide synthase, L-NG-monomethyl-arginine (L-NMMA) and noradrenaline on the vasodilator responses to bradykinin were examined in the forearm arterial bed of healthy volunteers. Noradrenaline was used as a control for vasoconstriction by L-NMMA; glyceryl trinitrate (GTN) as a control vasodilator acting independently of the NO synthase enzyme. 3. L-NMMA (4 mumol min-1; 5 min) alone reduced resting forearm blood flow by 44% (P < 0.01; n = 6) confirming that nitric oxide plays an important role in regulating vascular tone. 4. Bradykinin (10 and 100 pmol min-1; 3 min each dose) and GTN (2 and 5 nmol min-1; 3 min each dose) increased forearm blood flow in a dose-dependent manner (percentage changes 171 +/- 17% and 398 +/- 35%, and 176 +/- 21% and 268 +/- 42%, respectively; n = 6). 5. The response to bradykinin, but not that to GTN, was attenuated by L-NMMA compared with noradrenaline (P < 0.05; n = 6), suggesting that bradykinin-induced vasodilatation in the forearm is mediated, at least in part, by stimulating release of nitric oxide. PMID:7833219

  15. Haemodynamics and plasma concentrations following sublingual GTN and intravenous, or inhaled, isosorbide dinitrate.

    PubMed Central

    Culling, W; Singh, H; Bashir, A; Griffiths, B E; Dalal, J J; Sheridan, D J

    1984-01-01

    We measured plasma nitrate levels and haemodynamics following sublingual glyceryl trinitrate (GTN) (0.5 mg), or isosorbide dinitrate (ISDN) administered intravenously (0.5 mg) or by inhalation (1.25 mg) in 23 patients undergoing cardiac catheterisation for investigation of chest pain. Peak levels were detected at 90 s and 5 min following intravenous and inhaled ISDN respectively and at 3 min following sublingual GTN. Intravenous and inhaled ISDN produced similar plasma levels at 30 s and both were significantly greater than following sublingual GTN. Plasma levels were maintained for longer following inhaled ISDN than intravenous ISDN or sublingual GTN. Haemodynamic responses were qualitatively similar following each treatment; reduction in pulmonary vascular resistance and pressure and left ventricular end diastolic pressure occurred in each group. Heart rate, cardiac output and LV dP/dt.P-1 remained unchanged. Maximal haemodynamic responses were greater following ISDN than GTN, with little difference between the two preparations of ISDN. Haemodynamic responses were more sustained following inhaled ISDN than following sublingual GTN or intravenous ISDN, the latter two being similar in this respect. These findings suggest that inhaled ISDN may provide more rapid and sustained relief from angina than sublingual GTN. PMID:6422972

  16. Chronic administration of the HNO donor Angeli's salt does not lead to tolerance, cross-tolerance, or endothelial dysfunction: comparison with GTN and DEA/NO.

    PubMed

    Irvine, Jennifer C; Kemp-Harper, Barbara K; Widdop, Robert E

    2011-05-01

    Nitroxyl (HNO) displays distinct pharmacology to its redox congener nitric oxide (NO(•)) with therapeutic potential in the treatment of heart failure. It remains unknown if HNO donors are resistant to tolerance development following chronic in vivo administration. Wistar-Kyoto rats received a 3-day subcutaneous infusion of one of the NO(•) donors, glyceryl trinitrate (GTN) or diethylamine/NONOate (DEA/NO), or the HNO donor Angeli's salt (AS). GTN infusion (10 μg/kg/min) resulted in significantly blunted depressor responses to intravenous bolus doses of GTN, demonstrating tolerance development. By contrast, infusion with AS (20 μg/kg/min) or DEA/NO (2 μg/kg/min) did not alter their subsequent depressor responses. Similarly, ex vivo vasorelaxation responses in isolated aortae revealed that GTN infusion elicited a significant 6-fold decrease in the sensitivity to GTN and reduction in the maximum response to acetylcholine (ACh). Chronic infusion of AS or DEA/NO had no effect on subsequent vasorelaxation responses to themselves or to ACh. No functional cross-tolerance between nitrovasodilators was evident, either in vivo or ex vivo, although an impaired ability of a nitrovasodilator to increase tissue cGMP content was not necessarily indicative of a reduced functional response. In conclusion, HNO donors may represent novel therapies for cardiovascular disease with therapeutic potential over clinically used organic nitrates.

  17. Determination of tackiness of chitosan film-coated pellets exploiting minimum fluidization velocity.

    PubMed

    Fernández Cervera, M; Heinämäki, J; Räsänen, E; Antikainen, O; Nieto, O M; Iraizoz Colarte, A; Yliruusi, J

    2004-08-20

    The tackiness of aqueous chitosan film coatings and effects of anti-sticking agents on sticking tendency, were evaluated. A novel rapid method exploiting minimum fluidization velocity to determine tackiness was introduced and tested. The pressure difference over the miniaturized fluidized-bed was precisely recorded as a function of velocity of fluidization air. High molecular weight chitosan plasticized with glycerol was used as a film-forming agent. Magnesium stearate, titanium dioxide, colloidal silicon dioxide and glyceryl-1-monostearate (GMS) were studied as anti-sticking agents. Film coatings were performed in a miniaturized top-spray coater. The incorporation of anti-sticking agents led to a clear decrease in tackiness of the chitosan films, and magnesium stearate and GMS were shown the most effective. Film-coated pellets containing magnesium stearate and GMS as an anti-sticking agent were very easily fluidized (showing very low values of minimum fluidization velocity) and were thus classified as the best flowing and the least sticking samples. Both these additives were found anti-sticking agents of choice for aqueous chitosan film coatings. Determination of the experimental minimum fluidization velocity in a fluidized bed, is a useful and sensitive method of measuring the tackiness tendency of film-coated pellets.

  18. Glaucoma therapy by extended release of timolol from nanoparticle loaded silicone-hydrogel contact lenses.

    PubMed

    Jung, Hyun Jung; Abou-Jaoude, Michelle; Carbia, Blanca E; Plummer, Caryn; Chauhan, Anuj

    2013-01-10

    Glaucoma is the second major cause of blindness in the world after cataract. Glaucoma management through eye drops that reduce the intraocular pressure (IOP) has major deficiencies including low patient compliance and low bioavailability. Extended wear contact lenses that deliver glaucoma drugs for extended periods could increase patient compliance, while also increasing the bioavailability. To develop extended wear contact lenses that can also provide extended glaucoma therapy, we disperse nanoparticles of PGT (propoxylated glyceryl triacylate) that contain a glaucoma drug timolol. The particles can also be loaded into prefabricated lenses by soaking the lenses in a solution of particles in ethanol. The particle loaded gels can release timolol in phosphate buffered saline (PBS) for about a month at room temperature. The most likely rate controlling mechanism is hydrolysis of the ester bond that links timolol to the PGT matrix, but other mechanisms such as water and drug diffusion, drug dissolution, drug-polymer chain cleavage, time-dependent drug permeability within the polymeric matrix, etc. may also be important. Nanoparticle incorporation in the silicone hydrogels results in reduction in ion and oxygen permeabilities, and an increase in modulus, and the impact on each of these properties is proportional to the particle loading. A gel with 5% particle loading can deliver timolol at therapeutic doses for about a month at room temperature, with a minimal impact on critical lens properties. Preliminary animal studies in Beagle dogs conducted with lenses in which particles are loaded by soaking the lenses in ethanol show a reduction in IOP.

  19. Non-hemodynamic effects of organic nitrates and the distinctive characteristics of pentaerithrityl tetranitrate.

    PubMed

    Gori, Tommaso; Daiber, Andreas

    2009-01-01

    Organic nitrates are among the oldest and yet most commonly employed drugs in the long-term therapy of coronary artery disease and congestive heart failure. While they have long been used in clinical practice, our understanding of their mechanism of action and side effects remains incomplete. For instance, recent findings provide evidence of previously unanticipated, non-hemodynamic properties that include potentially beneficial mechanisms (such as the induction of a protective phenotype that mimics ischemic preconditioning), but also toxic effects (such as endothelial and autonomic dysfunction, rebound angina, tolerance). To date, the most commonly employed organic nitrates are isosorbide mononitrate, isosorbide dinitrate, and nitroglycerin (glyceryl trinitrate). Another organic nitrate, pentaerithrityl tetranitrate (PETN), has long been employed in eastern European countries and is currently being reintroduced in Western countries. In light of their wide use, and of the (re)introduction of PETN in Western markets, the present review focuses on the novel effects of organic nitrates, describing their potential clinical implications and discussing differences among different compounds. We believe that these recent findings have important clinical implications. Since the side effects of organic nitrates such as nitroglycerin and isosorbides appear to be mediated by reactive oxygen species, care should be taken that drugs with antioxidant properties are co-administered. On the other hand, efforts should be made to clinically exploit the preconditioning effects of these drugs.

  20. [Recent findings on nitrates: their action, bioactivation and development of tolerance].

    PubMed

    Münzel, T

    2008-10-01

    Organic nitrates still are one of the most important drug classes used in the treatment of an acute coronary syndrome and stable coronary artery disease as well as acute and chronic congestive heart failure. The mechanism of vasodilatation comprises the release of nitric oxide, which in turn activates soluble guanylate cyclase and lowers the intracellular calcium content leading to relaxation of vascular smooth muscle. Recent research has demonstrated that highly reactive nitrates, such as nitroglycerin (or glyceryl trinitrate) and pentaerthrityl tetranitrate (PETN) are bioactivated by aldehyde dehydrogenase 2 (ALDH-2), an enzyme located in mitochondria. The enzyme, which bioactivates mono- and dinitrates is not yet identified. Despite being effective in the acute treatment of patients, its long-term efficacy is limited by the development of tolerance to nitrates and of endothelial dysfunction. Both of these side effects of nitrate therapy are due to increased production of reactive oxygen species. This review focuses on new aspects of the process of bioactivation of organic nitrates, the conception of oxidative stress of endothelial dysfunction and of the development of tolerance and their therapeutic consequences. Also discussed are more recent findings on nitric oxide donors such as molsidomine, PETN and the combination treatment of isosorbide dinitrate and hydralazine of patients with coronary artery disease and chronic heart failure.

  1. Synthesis and preliminary investigations of the siRNA delivery potential of novel, single-chain rigid cationic carotenoid lipids.

    PubMed

    Pungente, Michael D; Jubeli, Emile; Øpstad, Christer L; Al-Kawaz, Mais; Barakat, Nour; Ibrahim, Tarek; Abdul Khalique, Nada; Raju, Liji; Jones, Rachel; Leopold, Philip L; Sliwka, Hans-Richard; Partali, Vassilia

    2012-03-16

    The success of nucleic acid delivery requires the development of safe and efficient delivery vectors that overcome cellular barriers for effective transport. Herein we describe the synthesis of a series of novel, single-chain rigid cationic carotenoid lipids and a study of their preliminary in vitro siRNA delivery effectiveness and cellular toxicity. The efficiency of siRNA delivery by the single-chain lipid series was compared with that of known cationic lipid vectors, 3β-[N-(N',N'-dimethylaminoethane)carbamoyl]-cholesterol (DC-Chol) and 1,2-dimyristoyl-sn-glyceryl-3-phosphoethanolamine (EPC) as positive controls. All cationic lipids (controls and single-chain lipids) were co-formulated into liposomes with the neutral co-lipid, 1,2-dioleolyl-sn-glycerol-3-phosphoethanolamine (DOPE). Cationic lipid-siRNA complexes of varying (+/-) molar charge ratios were formulated for delivery into HR5-CL11 cells. Of the five single-chain carotenoid lipids investigated, lipids 1, 2, 3 and 5 displayed significant knockdown efficiency with HR5-CL11 cells. In addition, lipid 1 exhibited the lowest levels of cytotoxicity with cell viability greater than 80% at all (+/-) molar charge ratios studied. This novel, single-chain rigid carotenoid-based cationic lipid represents a new class of transfection vector with excellent cell tolerance, accompanied with encouraging siRNA delivery efficiency.

  2. Influence of surfactant and lipid type on the physicochemical properties and biocompatibility of solid lipid nanoparticles.

    PubMed

    Pizzol, Carine Dal; Filippin-Monteiro, Fabíola Branco; Restrepo, Jelver Alexander Sierra; Pittella, Frederico; Silva, Adny Henrique; Alves de Souza, Paula; Machado de Campos, Angela; Creczynski-Pasa, Tânia Beatriz

    2014-08-20

    Nine types of solid lipid nanoparticle (SLN) formulations were produced using tripalmitin (TPM), glyceryl monostearate (GM) or stearic acid (SA), stabilized with lecithin S75 and polysorbate 80. Formulations were prepared presenting PI values within 0.25 to 0.30, and the physicochemical properties, stability upon storage and biocompatibility were evaluated. The average particle size ranged from 116 to 306 nm, with a negative surface charge around -11 mV. SLN presented good stability up to 60 days. The SLN manufactured using SA could not be measured by DLS due to the reflective feature of this formulation. However, TEM images revealed that SA nanoparticles presented square/rod shapes with an approximate size of 100 nm. Regarding biocompatibility aspects, SA nanoparticles showed toxicity in fibroblasts, causing cell death, and produced high hemolytic rates, indicating toxicity to red blood cells. This finding might be related to lipid type, as well as, the shape of the nanoparticles. No morphological alterations and hemolytic effects were observed in cells incubated with SLN containing TPM and GM. The SLN containing TPM and GM showed long-term stability, suggesting good shelf-life. The results indicate high toxicity of SLN prepared with SA, and strongly suggest that the components of the formulation should be analyzed in combination rather than separately to avoid misinterpretation of the results.

  3. Computational Models of the Gastrointestinal Environment. 2. Phase Behavior and Drug Solubilization Capacity of a Type I Lipid-Based Drug Formulation after Digestion.

    PubMed

    Birru, Woldeamanuel A; Warren, Dallas B; Han, Sifei; Benameur, Hassan; Porter, Christopher J H; Pouton, Colin W; Chalmers, David K

    2017-03-06

    Lipid-based drug formulations can greatly enhance the bioavailability of poorly water-soluble drugs. Following the oral administration of formulations containing tri- or diglycerides, the digestive processes occurring within the gastrointestinal (GI) tract hydrolyze the glycerides to mixtures of free fatty acids and monoglycerides that are, in turn, solubilized by bile. The behavior of drugs within the resulting colloidal mixtures is currently not well characterized. This work presents matched in vitro experimental and molecular dynamics (MD) theoretical models of the GI microenvironment containing a digested triglyceride-based (Type I) drug formulation. Both the experimental and theoretical models consist of molecular species representing bile (glycodeoxycholic acid), digested triglyceride (1:2 glyceryl-1-monooleate and oleic acid), and water. We have characterized the phase behavior of the physical system using nephelometry, dynamic light scattering, and polarizing light microscopy and compared these measurements to phase behavior observed in multiple MD simulations. Using this model microenvironment, we have investigated the dissolution of the poorly water-soluble drug danazol experimentally using LC-MS and theoretically by MD simulation. The results show how the formulation lipids alter the environment of the GI tract and improve the solubility of danazol. The MD simulations successfully reproduce the experimental results showing the utility of MD in modeling the fate of drugs after digestion of lipid-based formulations within the intestinal lumen.

  4. Development and characterization of novel hydrogel containing antimicrobial drug for treatment of burns

    PubMed Central

    Thakkar, Vaishali; Korat, Vaishali; Baldaniya, Lalji; Gohel, Mukesh; Gandhi, Tejal; Patel, Nirav

    2016-01-01

    Introduction: The aim of burn management and therapy is fast healing and epithelisation to prevent infection. The present study is concerned with the development and characterization of a novel nanaoparticulate system; cubosomes, loaded with silver sulfadiazine (SSD) and Aloe vera for topical treatment of infected burns. Methods: Cubosome dispersions were formulated by an emulsification technique using different concentrations of a lipid phase Glyceryl Monooleate (GMO) and Poloxamer 407. The optimum formulae were incorporated in an aloe vera gel containing carbopol 934, to form cubosomal hydrogels (cubogels). The cubogels were characterized by in vitro release of SSD, rheological properties, pH, bioadhesion, Transmission Electron Microscopy and in-vivo Wound Healing Study. Results: The results show that the different concentration of GMO had significant effect on particle size, % EE and in vitro drug release. From the in-vitro drug release pattern and similarity factor (f2), it was concluded that batch CG3 (15% GMO and 1% P407) exhibited complete and controlled drug release within 12 hour (i.e. 98.25%), better bio adhesion and superior burn healing as compared to the marketed product. Conclusion: The in vivo burns healing study in rats revealed that the prepared optimized cubogel containing SSD and aloe vera has superior burns healing rate than cubogel with only SSD and marketed preparation so, it may be successfully used in the treatment of deep second degree burn. PMID:27606259

  5. Enhanced Oral Bioavailability of Efavirenz by Solid Lipid Nanoparticles: In Vitro Drug Release and Pharmacokinetics Studies

    PubMed Central

    Gaur, Praveen Kumar; Mishra, Shikha; Bajpai, Meenakshi; Mishra, Anushika

    2014-01-01

    Solid lipid nanoparticle is an efficient lipid based drug delivery system which can enhance the bioavailability of poorly water soluble drugs. Efavirenz is a highly lipophilic drug from nonnucleoside inhibitor category for treatment of HIV. Present work illustrates development of an SLN formulation for Efavirenz with increased bioavailability. At first, suitable lipid component and surfactant were chosen. SLNs were prepared and analyzed for physical parameters, stability, and pharmacokinetic profile. Efavirenz loaded SLNs were formulated using Glyceryl monostearate as main lipid and Tween 80 as surfactant. ESLN-3 has shown mean particle size of 124.5 ± 3.2 nm with a PDI value of 0.234, negative zeta potential, and 86% drug entrapment. In vitro drug release study has shown 60.6–98.22% drug release in 24 h by various SLN formulations. Optimized SLNs have shown good stability at 40°C ± 2°C and 75 ± 5% relative humidity (RH) for 180 days. ESLN-3 exhibited 5.32-fold increase in peak plasma concentration (Cmax⁡) and 10.98-fold increase in AUC in comparison to Efavirenz suspension (ES). PMID:24967360

  6. Process and formulation variables in the preparation of wax microparticles by a melt dispersion technique. I. Oil-in-water technique for water-insoluble drugs.

    PubMed

    Bodmeier, R; Wang, J; Bhagwatwar, H

    1992-01-01

    Ibuprofen-wax (carnauba, paraffin, beeswax, and the semisynthetic glyceryl esters--Gelucire 64/02 and Precirol ATO5) microparticles were prepared without organic solvents as an alternative to polymeric microparticles. In the melt dispersion technique, the drug-wax melt was emulsified into a heated aqueous phase followed by cooling to form the microparticles. The microparticles were characterized with respect to their drug loading, and morphological and release properties. They were spherical and non-agglomerated and drug loading close to 60 per cent were achieved. The more hydrophilic waxes (Gelucire 64/02 or Precirol ATO5) could be prepared without the use of surfactants. With the other waxes, increasing amounts of sodium lauryl sulphate in the external aqueous phase decreased the drug loading because of drug solubilization when compared to the polymeric stabilizer, poly(vinyl alcohol). The type of wax, the rate of cooling, and the temperature of the aqueous phase had no significant effect on the drug loading because of the low solubility of the drug in the external aqueous phase. The drug release was controlled by the hydrophobicity of the wax. Besides ibuprofen, other water-soluble drugs (ketoprofen, indomethacin, hydrocortisone) were also encapsulated by this method. The wax microparticles could be formulated into an aqueous sustained-release oral suspension dosage form.

  7. Formulating fluticasone propionate in novel PEG-containing nanostructured lipid carriers (PEG-NLC).

    PubMed

    Doktorovová, Slavomíra; Araújo, Joana; Garcia, Marisa L; Rakovský, Erik; Souto, Eliana B

    2010-02-01

    The aim of this study was to develop nanostructured lipid carriers (NLC) for topical delivery of fluticasone propionate (FP) with the aim to further improve the safety profile and decrease the adverse-side effects commonly reported in topical corticotherapy. NLC are colloidal drug-carriers consisting of a blend of a solid lipid and a small amount of liquid lipid since these carriers have proved to be effective in epidermal targeting in particular of glucocorticoids. NLC consisting of glyceryl palmito-stearate, and PEG-containing medium chain triglycerides mixture, stabilised by polysorbate 80 and soybean phosphatidylcholine were prepared. A mean particle size between 380 and 408 nm and entrapment efficacy of 95% were obtained for FP-loaded NLC. The crystallinity and polymorphic phase behaviour of FP-free and FP-loaded NLC were examined by differential scanning calorimetry and wide angle X-ray diffraction. Results revealed a low-crystalline structure and confirmed the incorporation of FP into the particles. The suitability of PEG-containing liquid lipids to form the lipid matrix of NLC was also confirmed.

  8. Role of Met93 and Thr96 in the lid hinge region of Rhizopus chinensis lipase.

    PubMed

    Zhu, Shan-Shan; Li, Ming; Yu, Xiaowei; Xu, Yan

    2013-05-01

    We engineered Rhizopus chinensis lipase to study its critical amino acid role in catalytic properties. Based on the amino acid sequence and three-dimensional model of the lipase, residues located in its lid hinge region (Met93 and Thr96) were replaced with corresponding amino acid residues (Ile93 and Asn96) found in the lid hinge region of Rhizopus oryzae lipase. The substitutions in the lid hinge region affected not only substrate specificity but also the thermostability of the lipase. Both lipases preferred p-nitrophenyl laurate and glyceryl trilaurate (C12). However, the variant S4-3O showed a slight decline in activity toward long-chain fatty acid (C16-C18). When enzymes activities decreased by half, the temperature of the variant (45 °C) was 22 °C lower than the parent (67 °C), probably substantially destabilized the structure of the lid region. The interfacial kinetic analysis of S4-3O suggested that the lower catalytic efficiency was due to a higher K m* value. According to the lipase structure investigated, Ile93Met played a role of narrowing the size of the hydrophobic patch, which affected the substrate binding affinity, and Asn96Thr destabilized the structure of the lipase by disrupting the H-bond interaction in the lid region.

  9. Unexpected skin barrier influence from nonionic emulsifiers.

    PubMed

    Bárány, E; Lindberg, M; Lodén, M

    2000-02-15

    Skin disorders are often treated with creams containing various active substances. The creams also contain emulsifiers, which are surface-active ingredients used to stabilize the emulsion. Emulsifiers are potential irritants and in the present study the influence of stearic acid, glyceryl stearate, PEG-2, -9, -40, and -100 stearate, steareth-2, -10 and -21 on normal as well as on irritated skin have been evaluated with non-invasive measurements. Test emulsions were created by incorporating 5% emulsifiers in a water/mineral oil mixture (50:50). The emulsions and their vehicle were then applied to normal skin for 48 h and to sodium lauryl sulfate (SLS) damaged skin for 17 h in aluminum chambers. Twenty-four hours after removal of the chambers the test sites were evaluated for degree of irritation. In normal skin, the emulsifiers induced significant differences in TEWL but not in skin blood flow. Five of the emulsifiers increased TEWL. In SLS-damaged skin an aggravation of the irritation was expected. However, no differences regarding skin blood flow was noted from the emulsifiers. Furthermore, three emulsifiers unexpectedly decreased TEWL. These results highlight the possibility of absorption of these emulsifiers into the lipid bilayer, which increase TEWL in normal skin and decrease TEWL in damaged skin.

  10. Towards Preserving the Immunogenicity of Protein Antigens Carried by Nanoparticles While Avoiding the Cold Chain

    PubMed Central

    Sloat, Brian R.; Sandoval, Michael A.; Cui, Zhengrong

    2010-01-01

    Nanoparticles are an attractive vaccine carrier with potent adjuvant activity. Data from our previous studies showed that immunization of mice with lecithin/glyceryl monostearate-based nanoparticles with protein antigens conjugated onto their surface induced a strong, quick, and long-lasting antigen-specific immune response. In the present study, we evaluated the feasibility of preserving the immunogenicity of protein antigens carried by nanoparticles without refrigeration using these antigen-conjugated nanoparticles as a model. The nanoparticles were lyophilized, and the immunogenicity of the antigens was evaluated in a mouse model using bovine serum albumin or the Bacillus anthracis protective antigen protein as model antigens. With proper excipients, the nanoparticles can be lyophilized while maintaining the immunogenicity of the antigens. Moreover, the immunogenicity of the model antigen conjugated onto the nanoparticles was undamaged after a relatively extended period of storage at room temperature or under accelerated conditions (37°C) when the nanoparticles were lyophilized with 5% mannitol plus 1% polyvinylpyrrolidone. To our knowledge, the present study represents an early attempt to preserve the immunogenicity of the protein antigens carried by nanoparticles without refrigeration. PMID:20416366

  11. Relationship between the size of nanoparticles and their adjuvant activity: Data from a study with an improved experimental design

    PubMed Central

    Li, Xinran; Sloat, Brian R.; Yanasarn, Nijaporn; Cui, Zhengrong

    2011-01-01

    There is a growing interest in identifying the relationship between the size of nanoparticles and their adjuvant activity, but the results from recent studies remain controversial. To address the controversy, it was thought that one should pay attention to the nanoparticle formulations to make sure that the antigen-loaded nanoparticles to be compared are not only different in particle size, but more importantly, as identical to each other as possible in all other formulation properties. In the present study, using ovalbumin (OVA) as a model antigen conjugated onto nanoparticles engineered from lecithin/glyceryl monostearate-in-water emulsions, we prepared OVA-nanoparticles of 230 nm and 708 nm. Before evaluating the immune responses induced by them in a mouse model, we made sure that: i) the sizes of the two OVA-nanoparticles did not extensively overlap, ii) the nanoparticles have similar zeta potentials and comparable antigen-loading, and iii) the nanoparticles did not aggregate when suspended in simulated biological media. We then showed that when subcutaneously injected into mice, the 230 nm OVA-conjugated nanoparticles induced stronger OVA-specific antibody and cellular immune responses than the 708 nm OVA-nanoparticles. Future studies attempting to correlate the size of nanoparticles and their adjuvant activities need to consider formulation parameters to ensure that the particles are different only in size and are stable before and after injection. PMID:21182941

  12. In-vitro/in-vivo correlation of pulsatile drug release from press-coated tablet formulations: a pharmacoscintigraphic study in the beagle dog.

    PubMed

    Ghimire, Manish; McInnes, Fiona J; Watson, David G; Mullen, Alexander B; Stevens, Howard N E

    2007-09-01

    The aim of the current study was to investigate the in-vitro and in-vivo performance of a press-coated tablet (PCT) intended for time delayed drug release, consisting of a rapidly disintegrating theophylline core tablet, press-coated with barrier granules containing glyceryl behenate (GB) and low-substituted hydroxypropylcellulose (L-HPC). The PCTs showed pulsatile release with a lag time dependent upon the GB and L-HPC composition of the barrier layer. In-vivo gamma-scintigraphic studies were carried out for PCTs containing GB:L-HPC at 65:35 w/w and 75:25 w/w in the barrier layer in four beagle dogs, in either the fed or fasted state. The in-vivo lag time in both the fed and fasted states did not differ significantly (p>0.05) from the in-vitro lag time. Additionally, no significant difference (p<0.05) between in-vivo fed and fasted disintegration times was observed, demonstrating that in-vivo performance of the PCT was not influenced by the presence or absence of food in the gastrointestinal tract. A distinct lag time was obtained prior to the appearance of drug in plasma and correlated (R2=0.98) with disintegration time observed from scintigraphic images. However, following disintegration, no difference in pharmacokinetic parameters (AUC(0-6 dis), K(el), Cmax) was observed. The current study highlighted the potential use of these formulations for chronopharmaceutical drug delivery.

  13. One-pot synthesis of quantum dot-labeled hydrophilic molecularly imprinted polymer nanoparticles for direct optosensing of folic acid in real, undiluted biological samples.

    PubMed

    Yang, Yaqiong; Wang, Zhengzheng; Niu, Hui; Zhang, Huiqi

    2016-12-15

    A facile and efficient one-pot approach for the synthesis of quantum dot (QD)-labeled hydrophilic molecularly imprinted polymer (MIP) nanoparticles for direct optosensing of folic acid (FA) in the undiluted bovine and porcine serums is described. Hydrophilic macromolecular chain transfer agent-mediated reversible addition-fragmentation chain transfer (RAFT) precipitation polymerization was used to implement the molecular imprinting of FA in the presence of CdTe quantum dots (QDs). The resulting FA-imprinted polymer nanoparticles with surface-grafted hydrophilic poly(glyceryl monomethacrylate) brushes and QDs labeling not only showed outstanding specific molecular recognition toward FA in biological samples, but also exhibited good photostability, rapid binding kinetics, and obvious template binding-induced fluorescence quenching. These characteristics make them a useful fluorescent chemosensor for directly and selectively optosensing FA in the undiluted bovine and porcine serums, with its limit of detection being 0.025μM and average recoveries ranging from 98% to 102%, even in the presence of several interfering compounds. This advanced fluorescent MIP chemosensor is highly promising for rapid quantification of FA in such applications as clinical diagnostics and food analysis.

  14. CO{sub 2}-philic oligomers as novel solvents for CO{sub 2} absorption

    SciTech Connect

    Miller, Matthew B; Luebke, David R; Enick, Robert M

    2010-01-01

    Desirable properties for an oligomeric CO{sub 2}-capture solvent in an integrated gasification combined cycle (IGCC) plant include high selectivity for CO{sub 2} over H{sub 2} and water, low viscosity, low vapor pressure, low cost, and minimal environmental, health, and safety impacts. The neat solvent viscosity and solubility of CO{sub 2}, measured via bubble-point loci and presented on a pressure−composition diagram (weight basis), and water miscibility in CO{sub 2}-philic solvents have been determined and compared to results obtained with Selexol, a commercial oligomeric CO{sub 2} solvent. The solvents tested include polyethyleneglycol dimethylether (PEGDME), polypropyleneglycol dimethylether (PPGDME), polypropyleneglycol diacetate (PPGDAc), polybutyleneglycol diacetate (PBGDAc), polytetramethyleneetherglycol diacetate (PTMEGDAc), glyceryl triacetate (GTA), polydimethyl siloxane (PDMS), and perfluorpolyether (PFPE) that has a perfluorinated propyleneglycol monomer unit. Overall, PDMS and PPGDME are the best oligomeric solvents tested and exhibit properties that make them very promising alternatives for the selective absorption of CO{sub 2} from a mixed gas stream, especially if the absorption of water is undesirable.

  15. Patellar Tendinopathy

    PubMed Central

    Schwartz, Aaron; Watson, Jonathan N.; Hutchinson, Mark R.

    2015-01-01

    Context: Patellar tendinopathy is a common condition. There are a wide variety of treatment options available, the majority of which are nonoperative. No consensus exists on the optimal method of treatment. Evidence Acquisition: PubMed spanning 1962-2014. Study Design: Clinical review. Level of Evidence: Level 4. Results: The majority of cases resolve with nonoperative therapy: rest, physical therapy with eccentric exercises, cryotherapy, anti-inflammatories, corticosteroid injections, extracorporeal shockwave therapy, glyceryl trinitrate, platelet-rich plasma injections, and ultrasound-guided sclerosis. Refractory cases may require either open or arthroscopic debridement of the patellar tendon. Corticosteroid injections provide short-term pain relief but increase risk of tendon rupture. Anti-inflammatories and injectable agents have shown mixed results. Surgical treatment is effective in many refractory cases unresponsive to nonoperative modalities. Conclusion: Physical therapy with an eccentric exercise program is the mainstay of treatment for patellar tendinopathy. Platelet-rich plasma has demonstrated mixed results; evidence-based recommendations on its efficacy cannot be made. In the event that nonoperative treatment fails, surgical intervention has produced good to excellent outcomes in the majority of patients. PMID:26502416

  16. Methods of analysis for 2-dodecylcyclobutanone and studies to support its role as a unique marker of food irradiation.

    PubMed

    Driffield, M; Speck, D; Lloyd, A S; Parmar, M; Crews, C; Castle, L; Thomas, C

    2014-03-01

    Methods of analysis for 2-dodecylcyclobutanone (2-DCB) using gas chromatography with mass spectrometric detection (GC-MS), liquid chromatography with time-of-flight mass spectrometric detection (LC-TOF-MS) and LC with tandem MS (MS/MS) detection have been developed and optimised for maximum sensitivity to allow very low irradiation doses to be detected. The LC-MS/MS method, following derivatisation with 2,4-dinitrophenylhydrazine, was found to be the most sensitive technique and was used to determine the amount of 2-DCB formed from the model compounds palmitic acid, glyceryl tripalmitate and 1,3-dipalmitoyl-2-oleoylglycerol irradiated over a range of doses by two different irradiation sources (gamma and electron beam). The model compounds were also treated with a number of non-irradiation based processing techniques including heating in the presence and absence of oxygen, light, and redox active metal salts, in a conventional oven, microwave oven and pressure cooker. No 2-DCB was detected in any of the processed non-irradiated model compounds, reaffirming the hypothesis that 2-DCB is a unique radiolytic product that can be used as a marker of irradiation in foodstuffs.

  17. Ketone body therapy: from the ketogenic diet to the oral administration of ketone ester

    PubMed Central

    Hashim, Sami A.; VanItallie, Theodore B.

    2014-01-01

    Ketone bodies (KBs), acetoacetate and β-hydroxybutyrate (βHB), were considered harmful metabolic by-products when discovered in the mid-19th century in the urine of patients with diabetic ketoacidosis. It took physicians many years to realize that KBs are normal metabolites synthesized by the liver and exported into the systemic circulation to serve as an energy source for most extrahepatic tissues. Studies have shown that the brain (which normally uses glucose for energy) can readily utilize KBs as an alternative fuel. Even when there is diminished glucose utilization in cognition-critical brain areas, as may occur early in Alzheimer’s disease (AD), there is preliminary evidence that these same areas remain capable of metabolizing KBs. Because the ketogenic diet (KD) is difficult to prepare and follow, and effectiveness of KB treatment in certain patients may be enhanced by raising plasma KB levels to ≥2 mM, KB esters, such as 1,3-butanediol monoester of βHB and glyceryl-tris-3-hydroxybutyrate, have been devised. When administered orally in controlled dosages, these esters can produce plasma KB levels comparable to those achieved by the most rigorous KD, thus providing a safe, convenient, and versatile new approach to the study and potential treatment of a variety of diseases, including epilepsy, AD, and Parkinson’s disease. PMID:24598140

  18. Ketone body therapy: from the ketogenic diet to the oral administration of ketone ester.

    PubMed

    Hashim, Sami A; VanItallie, Theodore B

    2014-09-01

    Ketone bodies (KBs), acetoacetate and β-hydroxybutyrate (βHB), were considered harmful metabolic by-products when discovered in the mid-19th century in the urine of patients with diabetic ketoacidosis. It took physicians many years to realize that KBs are normal metabolites synthesized by the liver and exported into the systemic circulation to serve as an energy source for most extrahepatic tissues. Studies have shown that the brain (which normally uses glucose for energy) can readily utilize KBs as an alternative fuel. Even when there is diminished glucose utilization in cognition-critical brain areas, as may occur early in Alzheimer's disease (AD), there is preliminary evidence that these same areas remain capable of metabolizing KBs. Because the ketogenic diet (KD) is difficult to prepare and follow, and effectiveness of KB treatment in certain patients may be enhanced by raising plasma KB levels to ≥2 mM, KB esters, such as 1,3-butanediol monoester of βHB and glyceryl-tris-3-hydroxybutyrate, have been devised. When administered orally in controlled dosages, these esters can produce plasma KB levels comparable to those achieved by the most rigorous KD, thus providing a safe, convenient, and versatile new approach to the study and potential treatment of a variety of diseases, including epilepsy, AD, and Parkinson's disease.

  19. The enigma of nitroglycerin bioactivation and nitrate tolerance: news, views and troubles

    PubMed Central

    Mayer, B; Beretta, M

    2008-01-01

    Nitroglycerin (glyceryl trinitrate; GTN) is the most prominent representative of the organic nitrates or nitrovasodilators, a class of compounds that have been used clinically since the late nineteenth century for the treatment of coronary artery disease (angina pectoris), congestive heart failure and myocardial infarction. Medline lists more than 15 000 publications on GTN and other organic nitrates, but the mode of action of these drugs is still largely a mystery. In the first part of this article, we give an overview on the molecular mechanisms of GTN biotransformation resulting in vascular cyclic GMP accumulation and vasodilation with focus on the role of mitochondrial aldehyde dehydrogenase (ALDH2) and the link between the ALDH2 reaction and activation of vascular soluble guanylate cyclase (sGC). In particular, we address the identity of the bioactive species that activates sGC and the potential involvement of nitrite as an intermediate, describe our recent findings suggesting that ALDH2 catalyses direct 3-electron reduction of GTN to NO and discuss possible reaction mechanisms. In the second part, we discuss contingent processes leading to markedly reduced sensitivity of blood vessels to GTN, referred to as vascular nitrate tolerance. Again, we focus on ALDH2 and describe the current controversy on the role of ALDH2 inactivation in tolerance development. Finally, we emphasize some of the most intriguing, in our opinion, unresolved puzzles of GTN pharmacology that urgently need to be addressed in future studies. PMID:18574453

  20. A redox-responsive mesoporous silica nanoparticle capped with amphiphilic peptides by self-assembly for cancer targeting drug delivery

    NASA Astrophysics Data System (ADS)

    Xiao, Dong; Jia, Hui-Zhen; Ma, Ning; Zhuo, Ren-Xi; Zhang, Xian-Zheng

    2015-05-01

    A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with nearly no leakage in the absence of dithiothreitol (DTT) or glutathione (GSH). With the addition of DTT or GSH, the entrapped drug released quickly due to the cleavage of the disulfide bond. It was found that after the internalization of MSNs by cancer cells via the receptor-mediated endocytosis, the surface amphiphilic peptides and alkyl chain of RRMSN/DOX were removed to induce rapid drug release intracellularly after the cleavage of the disulfide bond, triggered by GSH secreted in cancer cells. This novel intelligent RRMSN/DOX drug delivery system using self-assembly of amphiphilic peptides around the MSNs provides a facile, but effective strategy for the design and development of smart drug delivery for cancer therapy.A redox-responsive mesoporous silica nanoparticle (RRMSN) was developed as a drug nanocarrier by noncovalent functionalization of MSNs with amphiphilic peptides containing the RGD ligand. The alkyl chain stearic acid (C18) with a thiol terminal group was anchored on the surface of MSNs via a disulfide bond, and the amphiphilic peptide (AP) C18-DSDSDSDSRGDS was coated by self-assembly through hydrophobic interactions between the octadecyl groups of MSNs and alkyl chains of AP, which played the role of a gatekeeper collectively. In vitro drug release profiles demonstrated that the anticancer drug (DOX) could be entrapped with