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Chromatography Analysis (chromatography + analysis)
Kinds of Chromatography Analysis Selected AbstractsComparing different floral resources on the longevity of a parasitic waspAGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2008Livy Williams III Abstract 1,The effects of floral resources of several important non-crop host plants of Lygus lineolaris on the longevity of Anaphes iole, one of its natural enemies, was studied. 2,Median longevity of A. iole wasps provisioned with floral resources (Erigeron annuus, Oenothera speciosa, Lamium amplexicaule, and Capsella bursa-pastoris) was in the range 1.27,3.24 days, and did not differ from wasps in the distilled water only control (1.46,2.81 days), but was less than median longevity of wasps provisioned with distilled water + sucrose (5.30,12.46 days). No difference in longevity was observed between gender, although females usually lived slightly longer than males. 3,High-performance anion-exchange chromatography analyses of O. speciosa floral nectar revealed that the major carbohydrate components were sucrose, glucose, and fructose. 4,The results indicate that the floral resources of some non-crop plants that serve as important reproductive hosts for L. lineolaris offer little or no benefit to A. iole. [source] Solid-supported amphiphilic triblock copolymer membranes grafted from gold surfaceJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 1 2009Ekaterina Rakhmatullina Abstract Gold-supported amphiphilic triblock copolymer brushes composed of two hydrophilic poly(2-hydroxyethyl methacrylate) (PHEMA) blocks and a hydrophobic poly(n -butyl methacrylate) (PBMA) middle part were synthesized using a surface-initiated ATRP. Attenuated total reflectance Fourier transform infrared spectroscopy, polarization modulation infrared reflection absorption spectroscopy (PM-IRRAS), ellipsometry, contact angle measurements, and atomic force microscopy were used for the characterization of PHEMA- co -PBMA- co -PHEMA brushes. The PM-IRRAS analysis revealed an increase of the chain tilt toward the gold surface during growth of the individual blocks. We suggest that the orientation of the amphiphilic polymer brushes is influenced by both the chain length and the interchain interactions. Additionally, a detachment of the polymer membranes from the solid support and subsequent gel permeation chromatography analyses allowed us to establish their compositions. We applied block-selective solvents (water and hexane) as well as a good solvent for the whole polymer chain (ethanol) to study the morphology and solvent responsive behavior of the amphiphilic brushes. The presented results could serve as a good starting point for the fabrication of functional solid-supported membranes for biosensing applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1,13, 2009 [source] Latices of poly(fluoroalkyl mathacrylate)- b -poly(butyl methacrylate) copolymers prepared via reversible addition,fragmentation chain transfer polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2007Xiaodong Zhou Abstract Poly(fluoroalkyl mathacrylate)- block -poly(butyl methacrylate) diblock copolymer latices were synthesized by a two-step process. In the first step, a homopolymer end-capped with a dithiobenzoyl group [poly(fluoroalkyl mathacrylate) (PFAMA) or poly(butyl methacrylate) (PBMA)] was prepared in bulk via reversible addition,fragmentation chain transfer (RAFT) polymerization with 2-cyanoprop-2-yl dithiobenzoate as a RAFT agent. In the second step, the homopolymer chain-transfer agent (macro-CTA) was dissolved in the second monomer, mixed with a water phase containing a surfactant, and then ultrasonicated to form a miniemulsion. Subsequently, the RAFT-mediated miniemulsion polymerization of the second monomer (butyl methacrylate or fluoroalkyl mathacrylate) was carried out in the presence of the first block macro-CTA. The influence of the polymerization sequence of the two kinds of monomers on the colloidal stability and molecular weight distribution was investigated. Gel permeation chromatography analyses and particle size results indicated that using the PFAMA macro-CTA as the first block was better than using the PBMA RAFT agent with respect to the colloidal stability and the narrow molecular weight distribution of the F-copolymer latices. The F-copolymers were characterized with 1H NMR, 19F NMR, and Fourier transform infrared spectroscopy. Comparing the contact angle of a water droplet on a thin film formed by the fluorinated copolymer with that of PBMA, we found that for the diblock copolymers containing a fluorinated block, the surface energy decreased greatly, and the hydrophobicity increased. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 471,484, 2007 [source] A Self-Assembling Polythiophene Functionalised with a Cysteine MoietyMACROMOLECULAR RAPID COMMUNICATIONS, Issue 9 2003Adele Mucci Abstract A new copolymer bearing a cysteine moiety, designed for molecular interaction, metal-ion detection, and chiral recognition, was synthesised starting from the dibromo derivative of methyl N -(tert -butoxycarbonyl)- S -thien-3-ylcysteinate and distannylthiophene through a Stille coupling reaction. UV-vis spectroscopy, circular dichroism, NMR spectroscopy, and gel permeation chromatography analyses evidenced that this polymer is able to form self-assembling structures, through the formation of a hydrogen-bond network, not only in the solid state but also in solution. [source] Biodegradation of atrazine in transgenic plants expressing a modified bacterial atrazine chlorohydrolase (atzA) genePLANT BIOTECHNOLOGY JOURNAL, Issue 5 2005Lin Wang Summary Atrazine is one of the most widely used herbicides in the USA. Atrazine chlorohydrolase (AtzA), the first enzyme in a six-step pathway leading to the mineralization of atrazine in Gram-negative soil bacteria, catalyses the hydrolytic dechlorination and detoxification of atrazine to hydroxyatrazine. In this study, we investigated the potential use of transgenic plants expressing atzA to take up, dechlorinate and detoxify atrazine. Alfalfa, Arabidopsis thaliana and tobacco were transformed with a modified bacterial atzA gene, p -atzA, under the control of the cassava vein mosaic virus promoter. All transgenic plant species actively expressed p -atzA and grew over a wide range of atrazine concentrations. Thin layer chromatography analyses indicated that in planta expression of p -atzA resulted in the production of hydroxyatrazine. Hydroponically grown transgenic tobacco and alfalfa dechlorinated atrazine to hydroxyatrazine in leaves, stems and roots. Moreover, p -atzA was found to be useful as a conditional-positive selection system to isolate alfalfa and Arabidopsis transformants following Agrobacterium -mediated transformation. Our work suggests that the in planta expression of p -atzA may be useful for the development of plants for the phytoremediation of atrazine-contaminated soils and soil water, and as a marker gene to select for the integration of exogenous DNA into the plant genome. [source] Enthalpy relaxation in bisphenol-A polycarbonate/poly(methyl methacrylate) blendsPOLYMER ENGINEERING & SCIENCE, Issue 3 2007Maurizio Penco Bisphenol-A polycarbonate (PC)/poly(methyl methacrylate) (PMMA) blends (PC/PMMA) were prepared by melt mixing with and without a trans-esterification catalyst (tetrabutylammoniun tetraphenylborate), which is able to promote inter-exchange reactions between PC and PMMA. Evidences of the ester,ester exchange reaction taking place were pointed out via Fourier Transform Infra-Red and size exclusion chromatography analyses. A series of enthalpy relaxation measurements were carried out for the pure polymers and for blends thereof. The data were analyzed on the basis of the Tool,Narayanaswamy,Moynihan/Kohlraush,Williams,Watts model. This model characterizes the structural relaxation in the glass transition region by means of four parameters: the apparent activation energy (,h*), the nonlinearity (x), the nonexponentiality (,), and the pre-exponential factor (,0). The apparent activation energy can be determined from the cooling rate dependence of the fictive temperature (Tf) measured using DSC. ,h* values of homogeneous blend and of the starting polymers were determined in this way, while an estimation of x, , and ,0 was proposed. Comparisons were made between a single glass transition temperature PC/PMMA blend and homopolymers data. The experimental values of ,h* suggest that the degree of cooperativity decreases on going from the starting polymers to the blend. POLYM. ENG. SCI., 47:218,224, 2007. © 2007 Society of Plastics Engineers. [source] Synthesis and characterization of novel thermoplastic poly(oligophosphazene-urethane)sPOLYMER INTERNATIONAL, Issue 6 2009Yubo Zhou Abstract BACKGROUND: Polyurethanes are some of the most popular polymers used in a variety of products, such as coatings, adhesives, flexible and rigid foams, elastomers, etc. Despite the possibility of tailoring their properties, polyurethanes suffer a serious disadvantage of poor thermal stability. Many attempts have been made in order to improve the thermal stability of polyurethanes. RESULTS: A new hydroxyl-terminated oligomer containing sulfone groups, 2,2-bis(4-hydroxy-4,4-sulfonyldiphoneloxy)tetraphenoxyoligocyclotriphosphazene (HSPPZ), was synthesized. HSPPZ was characterized using Fourier transform infrared (FTIR), NMR and gel permeation chromatography analyses. A series of novel thermoplastic poly(oligophosphazene-urethane)s were then synthesized via the reaction of NCO-terminated polyurethane prepolymer with HSPPZ containing chain-extender diols. Their structure and properties were investigated using FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, water contact angle measurement and tensile measurements. CONCLUSION: Compared to conventional thermoplastic polyurethanes, poly(oligophosphazene-urethane)s exhibit better thermal stability, low-temperature resistance and hydrophobicity, but their mechanical properties are slightly poorer. Copyright © 2009 Society of Chemical Industry [source] Synthesis and characterization of hyperbranched polytriazole via an ,A2 + B3' approach based on click chemistryPOLYMER INTERNATIONAL, Issue 8 2008Jianda Xie Abstract BACKGROUND: The ,A2 + B3' type of polymerization has been demonstrated to be an alternative route towards hyperbranched polymers. Some highly crosslinked hyperbranched polymers have been prepared via copper(I)-catalyzed click reactions of multivalent azides and alkynes. To obtain hyperbranched polymers without gelation and develop the A2 + B3 type of polymerization based on click reactions, the specific reaction conditions need to be investigated. RESULTS: In this work, a hyperbranched polytriazole (hb -PTA) was synthesized through the A2 + B3 approach using a click reaction. 4- N,N,-bis(2-azidoethyl)amino-4,-nitroazobenzene and 1,3,5-tris(alynyloxy)benzene were synthesized for use as the A2 and B3 monomers, respectively. This was a ,one-pot' polymerization carried out using a slow-addition method. The obtained hb -PTA was soluble in common organic solvents. The molecular structure was characterized using 1H NMR, Fourier transform infrared and gel permeation chromatography analyses. The degree of branching of hb -PTA was determined to be around 0.50. CONCLUSION: The hb -PTA was successfully synthesized via the A2 + B3 approach based on a click reaction. The polymerization conducted in dilute solution adopting slow addition of A2 to B3 resulted in hb -PTA in the absence of gelation. The obtained hb -PTA exhibited high thermal stability. Copyright © 2008 Society of Chemical Industry [source] Functional role of the linker region in purified human P-glycoproteinFEBS JOURNAL, Issue 13 2009Tomomi Sato Human P-glycoprotein (P-gp), which conveys multidrug resistance, is an ATP-dependent drug efflux pump that transports a wide variety of structurally unrelated compounds out of cells. P-gp possesses a ,linker region' of , 75 amino acids that connects two homologous halves, each of which contain a transmembrane domain followed by a nucleotide-binding domain. To investigate the role of the linker region, purified human P-gp was cleaved by proteases at the linker region and then compared with native P-gp. Based on a verapamil-stimulated ATP hydrolase assay, size-exclusion chromatography analysis and a thermo-stability assay, cleavage of the P-gp linker did not directly affect the preservation of the overall structure or the catalytic process in ATP hydrolysis. However, linker cleavage increased the kcat values both with substrate (ksub) and without substrate (kbasal), but decreased the ksub/kbasal values of all 10 tested substrates. The former result indicates that cleaving the linker activates P-gp, while the latter result suggests that the linker region maintains the tightness of coupling between the ATP hydrolase reaction and substrate recognition. Inspection of structures of the P-gp homolog, MsbA, suggests that linker-cleaved P-gp has increased ATP hydrolase activity because the linker interferes with a conformational change that accompanies the ATP hydrolase reaction. Moreover, linker cleavage affected the specificity constants [ksub/Km(D)] for some substrates (i.e. linker cleavage probably shifts the substrate specificity profile of P-gp). Thus, this result also suggests that the linker region regulates the inherent substrate specificity of P-gp. [source] cDNA cloning and characterization of a novel calmodulin-like protein from pearl oyster Pinctada fucataFEBS JOURNAL, Issue 19 2005Shuo Li Calcium metabolism in oysters is a very complicated and highly controlled physiological and biochemical process. However, the regulation of calcium metabolism in oyster is poorly understood. Our previous study showed that calmodulin (CaM) seemed to play a regulatory role in the process of oyster calcium metabolism. In this study, a full-length cDNA encoding a novel calmodulin-like protein (CaLP) with a long C-terminal sequence was identified from pearl oyster Pinctada fucata, expressed in Escherichia coli and characterized in vitro. The oyster CaLP mRNA was expressed in all tissues tested, with the highest levels in the mantle that is a key organ involved in calcium secretion. In situ hybridization analysis reveals that CaLP mRNA is expressed strongly in the outer and inner epithelial cells of the inner fold, the outer epithelial cells of the middle fold, and the dorsal region of the mantle. The oyster CaLP protein, with four putative Ca2+ -binding domains, is highly heat-stable and has a potentially high affinity for calcium. CaLP also displays typical Ca2+ -dependent electrophoretic shift, Ca2+ -binding activity and significant Ca2+ -induced conformational changes. Ca2+ -dependent affinity chromatography analysis demonstrated that oyster CaLP was able to interact with some different target proteins from those of oyster CaM in the mantle and the gill. In summary, our results have demonstrated that the oyster CaLP is a novel member of the CaM superfamily, and suggest that the oyster CaLP protein might play a different role from CaM in the regulation of oyster calcium metabolism. [source] Microbial desulfurization of gasoline by free whole-cells of Rhodococcus erythropolis XPFEMS MICROBIOLOGY LETTERS, Issue 2 2006Bo Yu Abstract Rhodococcus erythropolis XP could grow well with condensed thiophenes, mono-thiophenic compounds and mercaptans present in gasoline. Rhodococcus erythropolis XP was also capable of efficiently degrading the condensed thiophenes in resting cell as well as biphasic reactions in which n -octane served as a model oil phase. Free whole cells of R. erythropolis XP were adopted to desulfurize fluid catalytic cracking (FCC) and straight-run (SR) gasoline oils. About 30% of the sulfur content of FCC gasoline and 85% of sulfur in SR gasoline were reduced, respectively. Gas chromatography analysis with atomic emission detection also showed depletion of sulfur compounds in SR gasoline. Rhodococcus erythropolis XP could partly resist the toxicity of gasoline and had an application potential to biodesulfurization of gasoline. [source] Is the axilla a distinct skin phenotype?INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Issue 1 2007A. Watkinson The axillary skin is cosmetically important with millions of consumers daily applying antiperspirant/deodorant products. Despite this, we know virtually nothing about axillary skin or how antiperspirant use impacts upon it. To characterize axillary stratum corneum and determine whether this is a unique skin type, we have evaluated a range of skin parameters, comparing these with the volar forearm. Trans-epidermal water loss and corneosurfametry revealed a reduced barrier function in the axilla. However, application of antiperspirant had no effect upon these barrier properties. High performance thin layer chromatography analysis of stratum corneum lipids demonstrated statistically elevated levels of fatty acids, ceramide and particularly cholesterol in the axilla. This modification of barrier lipid ratios appeared to result in a more ordered lipid lamellae phase behaviour, as determined by attenuated total reflectance Fourier transform infrared spectroscopy, with transition phase changes occurring at higher temperatures. Morphological differences were also seen in the cells of the axillary stratum corneum. Microscopic evaluation of axillary-cornified envelopes revealed them to be smaller, indicative of a shorter stratum corneum turnover. However, there appeared to be no significant difference corneocyte maturation. ,Skin dryness' squamometry measurements indicated that the axillary stratum corneum retained desquamated material on its surface more than on the forearm. This correlated with decreased levels of the desquamatory stratum corneum chymotryptic enzyme in the surface layers of the skin. These results indicate that the axilla has a distinct phenotype. Paper presented at the 22nd IFSCC Congress 2002, Edinburgh, Scotland [source] A pulsed electric field procedure for promoting Maillard reaction in an asparagine,glucose model systemINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2010Yong-Guang Guan Summary Effects of pulsed electric field (PEF) on pH, intermediate products, asparagine and glucose content, browning value, reducing power as well as antioxidant activity of an asparagine,glucose solution were explored in this paper. Results showed that the solution's UV,Vis absorbance at 294 nm and 420 nm was significantly increased from 0 to approximately 1.14 and 0.74, respectively, at PEF intensity of 40 kV cm,1 for 7.35 ms treatment. The temperature of PEF treated samples were overall lower than 40 °C. It was also detected that the antioxidant activity of treated sample was correspondingly increased by 20.33%. Meanwhile, 14% reduction of asparagine content and 66% reduction of glucose content were observed. It was demonstrated from high performance liquid chromatography analysis that Maillard reaction in the model system had been enhanced by PEF treatment as no 5-hydroxymethyl-2-furaldehyde was generated. This study indicates that pulsed electric field treatment, especially with higher intensities, is a means to significantly promote the Maillard reaction in an asparagine,glucose solution. [source] Production of conjugated linoleic acid by probiotic Lactobacillus acidophilus La-5JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009M. Macouzet Abstract Aims:, To study the ability of the probiotic culture Lactobacillus acidophilus La-5 to produce conjugated linoleic acid (CLA), which is a potent anti-carcinogenic agent. Methods and Results:, The conversion of linoleic acid to CLA was studied both by fermentation in a synthetic medium and by incubation of washed cells. Accumulation of CLA was monitored by gas chromatography analysis of the biomass and supernatants. While the fermentation conditions applied may not be optimal to observe CLA production in growing La-5 cells, the total CLA surpassed 50% of the original content in the washed cells after 48 h under both aerobic and micro-aerobic conditions. The restriction of oxygen did not increase the yield, but favoured the formation of trans, trans isomers. Conclusions:, The capability of L. acidophilus La-5 to produce CLA is not dependant on the presence of milk fat or anaerobic conditions. Regulation of CLA production in this strain needs to be further investigated to exploit the CLA potential in fermented foods. Significance and Impact of the study:, Knowledge gained through the conditions on the accumulation of CLA would provide further insight into the fermentation of probiotic dairy products. The capacity of the nongrowing cells to produce CLA is also of great relevance for the emerging nonfermented probiotic foods. [source] Aflatoxin Inactivation Using Aqueous Extract of Ajowan (Trachyspermum ammi) SeedsJOURNAL OF FOOD SCIENCE, Issue 1 2005Shruti S. Hajare ABSTRACT: Aqueous extract of ajowan seeds was found to contain an aflatoxin inactivation factor (IF). Thin layer chromatography analysis of the toxins after treatment with IF showed relative reduction of aflatoxin G1 > G2 > B1 > B2. Quantification of toxin using a fluorotoxin meter as well as the Enzyme Linked Immuno s orb ent Assay (ELISA) confirmed these findings. An approximate 80% reduction in total aflatoxin content over the controls was observed. This observed phenomenon of reduction in total toxin was referred to as toxin inactivation. Temperature was found to influence the rate of toxin inactivation. At 45 °C, it was found to be rapid during the initial 5 h and slowed later. The IF was found to retain considerable activity even after boiling and autoclaving, indicating partial heat stability. The activity was lost below pH 4.0. Above pH 4.0, it increased gradually, reaching the maximum at pH 10.0. IF was found to be stable to gamma irradiation. Toxin decontamination in spiked corn samples could be achieved using IF. This study emphasizes the potential of ajowan IF in aflatoxin removal from contaminated food commodities. However, the biological toxicity, if any, of the IF inactivated aflatoxins needs to be confirmed, and the work in this direction is in progress. [source] Fingerprinting Analysis of Rhizoma Chuanxiong of Commercial Types using 1H Nuclear Magnetic Resonance Spectroscopy and High Performance Liquid Chromatography MethodJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 6 2009Hai-Lin Qin Abstract The 1H nuclear magnetic resonance (1H NMR) fingerprints of fractionated non-polar extracts (control substance for a plant drug (CSPD) A) from Rhizoma chuanxiong, the rhizomes of Ligusticum chuanxiong Hort., of seven specimens from different sources were measured on Fourier Transform (FT)-NMR spectrometer and assigned by comparing them with the 1H NMR spectra of the isolated pure compounds. The 1H NMR fingerprints showed exclusively characteristic resonance signals of the major special constituents of the plant. Although the differences in the relative intensity of the 1H NMR signals due to a discrepancy in the ratio of the major constituents among these samples could be confirmed by high performance liquid chromatography analysis, the general features of the 1H NMR fingerprint established for an authentic sample of the rhizomes of L. chuanxiong exhibited exclusive data from those special compounds and can be used for authenticating L. Chuanxiong species. [source] Reconstitution of Photosystem II Reaction Center with Cu-Chlorophyll aJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 11 2006Shuang Liu Abstract An isolated photosystem (PS) II reaction center (RC) with altered pigment content was obtained by chemical exchange of native chlorophyll a (Chl) with externally added Cu-Chl a (Cu-Chl). Pigment composition and spectroscopic properties of the RC exchanged with Cu-Chl were compared with native RC and RC treated with Chl in the same way. High-performance liquid chromatography analysis showed approximately 0.5 Cu-Chl per two pheophytin in the Cu-Chl-reconstituted RC preparation. Insertion of Cu-Chl resulted in a decrease in absorption at 670 nm and an increase at 660 nm, suggesting that the peripheral Chl may have been displaced. Fluorescence emission spectra of the Cu-Chl-reconstituted RC displayed a marked decrease in fluorescence yield and a blue shift of the band maximum, accompanied by the appearance of a broad peak at a shorter wavelength, indicating that energy transfer in the modified RC was disturbed by Cu-Chl, a quencher of the excited state. However, there were few differences in the circular dichroism (CD) spectra, suggesting that the arrangement of pigments and proteins responsible for the CD signal was not significantly affected. In addition, no obvious change in peptide components was found after the exchange procedure. (Managing editor: Ping He) [source] The effect of temperature on the stability of compounds used as UV-MALDI-MS matrix: 2,5-dihydroxybenzoic acid, 2,4,6-trihydroxyacetophenone, ,-cyano-4-hydroxycinnamic acid, 3,5-dimethoxy-4-hydroxycinnamic acid, nor-harmane and harmaneJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2009Olga I. Tarzi Abstract The thermal stability of several commonly used crystalline matrix-assisted ultraviolet laser desorption/ionization mass spectrometry (UV-MALDI-MS) matrices, 2,5-dihydroxybenzoic acid (gentisic acid; GA), 2,4,6-trihydroxyacetophenone (THA), ,-cyano-4-hydroxycinnamic acid (CHC), 3,5-dimethoxy-4-hydroxycinnamic acid (sinapinic acid; SA), 9H-pirido[3,4-b]indole (nor-harmane; nor-Ho), 1-methyl-9H-pirido[3,4-b]indole (harmane; Ho), perchlorate of nor-harmanonium ([nor-Ho + H]+) and perchlorate of harmanonium ([Ho + H]+) was studied by heating them at their melting point and characterizing the remaining material by using different MS techniques [electron ionization mass spectrometry (EI-MS), ultraviolet laserdesorption/ionization-time-of-flight-mass spectrometry (UV-LDI-TOF-MS) and electrospray ionization-time-of-flight-mass spectrometry (ESI-TOF-MS)] as well as by thin layer chromatography analysis (TLC), electronic spectroscopy (UV-absorption, fluorescence emission and excitation spectrosco y) and 1H nuclear magnetic resonance spectroscopy (1H-NMR). In general, all compounds, except for CHC and SA, remained unchanged after fusion. CHC showed loss of CO2, yielding the trans-/cis -4-hydroxyphenylacrilonitrile mixture. This mixture was unambiguously characterized by MS and 1H-NMR spectroscopy, and its sublimation capability was demonstrated. These results explain the well-known cluster formation, fading (vanishing) and further recovering of CHC when used as a matrix in UV-MALDI-MS. Commercial SA (SA 98%; trans -SA/cis -SA 5 : 1) showed mainly cis- to- trans thermal isomerization and, with very poor yield, loss of CO2, yielding (3,,5,-dimethoxy-4,-hydroxyphenyl)-1-ethene as the decarboxilated product. These thermal conversions would not drastically affect its behavior as a UV-MALDI matrix as happens in the case of CHC. Complementary studies of the photochemical stability of these matrices in solid state were also conducted. Copyright © 2008 John Wiley & Sons, Ltd. [source] Scutellaria baicalensis and a constituent flavonoid, baicalein, attenuate ritonavir-induced gastrointestinal side-effectsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 11 2007Sangeeta Mehendale Ritonavir, a protease inhibitor drug, is commonly used in AIDS therapy. As with other chemotherapeutic drugs that cause gastrointestinal adverse effects, ritonavir treatment is associated with significant nausea and vomiting. This study investigated whether Scutellaria baicalensis, and its active flavonoid constituent, baicalein, attenuate the gastrointestinal effects of ritonavir. The effects of herb administration were evaluated in ritonavir-treated rats using a rat pica model, which simulates nausea and vomiting in humans. The effects of herb administration on gastric emptying in rats were also measured. Ritonavir treatment resulted in increased kaolin intake or severe pica, the intensity of which was reduced significantly with S. baicalensis administration (1 mg kg,1; P < 0.05). High-performance liquid chromatography analysis of S. baicalensis showed the presence of an extremely potent flavonoid constituent, baicalein. The study aimed to determine if baicalein contributed to the anti-pica effect of the extract. It was observed that baicalein dose-dependently decreased pica in ritonavir-treated rats (P < 0.001). In addition to inducing pica, ritonavir also significantly delayed gastric emptying, which could contribute to ritonavir-induced gastrointestinal dysfunction. When S. baicalensis extract was administered to ritonavir-treated rats the delayed gastric emptying was significantly attenuated (P < 0.05). The results suggest that S. baicalensis and the constituent baicalein reduce the gastrointestinal dysfunction caused by ritonavir. It is concluded that S. baicalensis may potentially have a role to play in reducing drug-induced adverse effects. [source] Stereocontrolled anionic alternating copolymerization of ethylphenylketene with benzaldehyde by a bisoxazoline ligandJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 21 2004Daisuke Nagai Abstract Anionic copolymerization of ethylphenylketene with benzaldehyde with butyllithium or diethylzinc as the initiator proceeded in a perfect 1:1 alternating manner to produce the corresponding polyester, whose repeating unit had two adjacent chiral centers. The relative stereochemistry between these two chiral centers was successfully controlled by the addition of (S,S)-(-)-2,2,-isopropylidenebis(4- tert -butyl-2-oxazoline), producing the corresponding polyester that had excellent diastereoselectivity (erythro -configuration : threo -configuration = 4:96). The diastereomeric ratio was determined by high-performance liquid chromatography analysis of the diol, which was obtained by reductive degradation of the polyester while maintaining the configuration of the repeating unit. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5384,5388, 2004 [source] Evaluation of use of a very short polar microbore column segment in high-speed gas chromatography analysisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 14 2008Peter Quinto Tranchida Abstract Very fast GC analyses are commonly carried out by using 10 m×0.1 mm id capillaries. In order to achieve rapid elution times (1,3 min), the latter are operated under suboptimum conditions. The present research is focused on the evaluation of use of a 0.1 mm id polar column segment (2 m), operated under near-to-optimum conditions, in very fast GC analysis. The results attained are compared with those derived from using a 10 m microbore column in very fast GC experiments. Prior to method development, the effects of gas velocity, temperature program rate, and sample amounts on analytical performance were evaluated. Following these preliminary applications, a complex lipidic sample, cod liver oil, was subjected to rapid separation (,2.1 min) on the 10 m capillary through the application of a 50°C/min temperature rate and a 130 cm/s gas velocity. The same matrix was analyzed on the 2 m capillary using the same temperature program rate and range, but with a close-to-ideal linear velocity. The results observed were of interest, as the separation was achieved in less time (1.45 min) with improved peak resolution. Finally, both methods were validated in terms of retention time and peak area repeatability, LOQ, and linearity. [source] Polyamines Contribute to Ethanol Withdrawal-Induced Neurotoxicity in Rat Hippocampal Slice Cultures Through Interactions With the NMDA ReceptorALCOHOLISM, Issue 7 2003D. Alex Gibson Background: Several reports demonstrate that withdrawal from long-term ethanol exposure is associated with significant central nervous system neurotoxicity, produced at least in part by increased activity of N -methyl-d-aspartate receptors (NMDARs). Recent evidence suggests that elevations in the synthesis and release of the polyamines spermidine and spermine, which are known modulators of NMDARs, contribute to the increased activity of the receptor during ethanol withdrawal. Therefore, the goal of this investigation was to examine what role, if any, spermidine and spermine have in the generation of ethanol withdrawal-induced neurotoxicity. Methods: Neurotoxicity (measured as fluorescence of the cell death indicator propidium iodide, PI), glutamate release (measured by high-performance liquid chromatography analysis), and polyamine concentrations (by high-performance liquid chromatography) were measured in rat hippocampal slice cultures undergoing withdrawal from chronic (10 day) ethanol exposure (100 mM). In addition, the effects of the polyamine synthesis inhibitor di-fluoro-methyl-ornithine (DFMO, 0.1,100 nM) and NMDAR polyamine-site antagonists ifenprodil, arcaine, and agmatine (1 nM-100 ,M) on ethanol withdrawal- and NMDA-induced neurotoxicity were measured. Results: Ethanol withdrawal significantly increased glutamate release (peaking at 18 hr with a 53% increase), increased concentrations of putrescine and spermidine (136% and 139% increases, respectively, at 18 hr), and produced significant cytotoxicity in the CA1 hippocampal region (56% increase in PI staining relative to controls) of the cultures. The cell death produced by ethanol withdrawal was significantly inhibited by ifenprodil (IC50= 14.9 nM), arcaine (IC50= 37.9 nM), agmatine (IC50= 41.5 nM), and DFMO (IC50= 0.6 nM). NMDA (5 ,M) significantly increased PI staining in the CA1 region of the hippocampal cultures (365% relative to controls), but ifenprodil, arcaine, agmatine, and DFMO all failed to significantly affect this type of toxicity. Conclusions: These data implicate a role for polyamines in ethanol withdrawal-induced neurotoxicity and suggest that inhibiting the actions of polyamines on NMDARs may be neuroprotective under these conditions. [source] A survey of ochratoxin A contamination in feeds and sera from organic and standard swine farms in northwest ItalyJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 9 2010Luisa Pozzo Abstract BACKGROUND: A survey was carried out on conventional (n = 11) and organic (n = 4) swine farms in northwest Italy in order to investigate the occurrence of ochratoxin A (OTA) in feed and serum samples collected from September 2006 to March 2009. Each farm was sampled twice and a total of 30 feed samples and 285 serum samples were collected. OTA levels were determined through extraction, immunoaffinity column purification and high-performance liquid chromatography analysis coupled with fluorimetric detection. RESULTS: All feed samples resulted to be contaminated with OTA at levels ranging from 0.22 to 38.4 µg kg,1. The OTA concentrations found in organic feed samples were significantly higher (P < 0.05) than those found in conventional feed samples. All serum samples resulted to be contaminated with OTA at levels ranging from 0.03 to 6.24 ng mL,1. The OTA concentrations found in organic serum samples were significantly higher (P < 0.001) than those found in conventional serum samples. CONCLUSION: None of the feed samples contained more than the maximum level (50 µg OTA kg,1, considering a feed moisture content of 120 g kg,1) recommended by the European Commission for OTA in complementary and complete swine feedstuffs. The OTA contamination of organic feed and serum samples was found to be significantly higher than that of conventional feed and serum samples. Copyright © 2010 Society of Chemical Industry [source] Isolation of eriocitrin (eriodictyol 7- O -rutinoside) as an arachidonate lipoxygenase inhibitor from Lumie fruit (Citrus lumia) and its distribution in Citrus speciesJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2007Yoichi Nogata Abstract An inhibitory compound acting against rat platelet 12-lipoxygenase was isolated from the peel of Lumie fruit (Citrus lumia) by activity-guided separation. It was identified as eriocitrin (eriodictyol 7- O -rutinoside) by spectroscopic analyses. Eriocitrin inhibited 5-lipoxygenase (IC5029.1 µmol L,1) from rat peritoneal polymorphonuclear leukocytes in addition to 12-lipoxygenase (IC5022.3 µmol L,1). Its aglycone, eriodictyol (5,7,3,, 4,-tetrahydroxyflavanone), was a much more potent inhibitor of both 12-lipoxygenase (IC500.07 µmol L,1) and 5-lipoxygenase (IC500.20 µmol L,1). It also inhibited the production of leukotriene B4 in intact peritoneal polymorphonuclear leukocytes stimulated with calcium ionophore A23187 (IC5012.7 µmol L,1). The distribution of eriocitrin in 39 citrus fruits was investigated by high-performance liquid chromatography analysis. Lumie, eureka lemon (Citrus limon), Sambokan (Citrus sulcata), Sudachi (Citrus sudachi) and Koji (Citrus leiocarpa) fruits were found to contain high levels of eriocitrin in both peel and juice vesicles. Copyright © 2006 Society of Chemical Industry [source] Mechanism of insoluble phosphate solubilization by Pseudomonas fluorescens RAF15 isolated from ginseng rhizosphere and its plant growth-promoting activitiesLETTERS IN APPLIED MICROBIOLOGY, Issue 2 2009K.-H. Park Abstract Aims:, To investigate the mechanism of insoluble phosphate (P) solubilization and plant growth-promoting activity by Pseudomonas fluorescens RAF15. Methods and Results:, We investigated the ability of Ps. fluorescens RAF15 to solubilize insoluble P via two possible mechanisms: proton excretion by ammonium assimilation and organic acid production. There were no clear differences in pH and P solubilization between glucose-ammonium and glucose-nitrate media. P solubilization was significantly promoted with glucose compared to fructose. Regardless of nitrogen sources used, Ps. fluorescens RAF15 solubilized little insoluble P with fructose. High performance liquid chromatography analysis showed that Ps. fluorescens RAF15 produced mainly gluconic and tartaric acids with small amounts of 2-ketogluconic, formic and acetic acids. During the culture, the pH was reduced with increase in gluconic acid concentration and was inversely correlated with soluble P concentration. Ps. fluorescens RAF1 showed the properties related to plant growth promotion: pectinase, protease, lipase, siderophore, hydrogen cyanide, and indoleacetic acid. Conclusion:, This study indicated that the P solubility was directly correlated with the organic acids produced. Significance and Impact of the Study:,Pseudomonas fluorescens RAF15 possessed different traits related to plant growth promotion. Therefore, Ps. fluorescens RAF15 could be a potential candidate for the development of biofertilizer or biocontrol agent. [source] Effects of Melanogenesis-Inducing Nitric Oxide and Histamine on the Production of Eumelanin and Pheomelanin in Cultured Human MelanocytesPIGMENT CELL & MELANOMA RESEARCH, Issue 1 2003Michael W. Lassalle Melanin pigments produced in human melanocytes are classified into two categories; black coloured eumelanin and reddish-yellow pheomelanin. Stimulation of melanocytes with ,-melanocyte-stimulating hormone (,-MSH), one of several melanogenic factors, has been reported to enhance eumelanogenesis to a greater degree than pheomelanogenesis, which contributes to hyperpigmentation in skin. Nitric oxide (NO) and histamine are also melanogenesis-stimulating factors that are released from cells surrounding melanocytes following ultraviolet (UV) irradiation. In this study, the effects of NO and histamine on the ratio of eumelanin and pheomelanin were examined in human melanocytes, and then compared with that of ,-MSH. The amounts of eumelanin and pheomelanin were quantified using high-performance liquid chromatography analysis after oxidation and hydrolysis of melanin. Melanogenesis was induced by the addition of ,-MSH, NO, or histamine to melanocytes. The amount of eumelanin production significantly increased with independent stimulation by these melanogenic factors, especially histamine, while that of pheomelanin significantly increased with ,-MSH and NO, but only slightly with histamine. As a result, the ratio of eumelanin and pheomelanin increased significantly with the addition of NO or histamine. These results suggest that NO and histamine, as in the case of ,-MSH, may contribute to UV-induced hyperpigmentation by enhancing eumelanogenesis. [source] New scope for synthesis of divinyl ether and maleic anhydride copolymer with narrow molecular mass distribution,POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 10-12 2002I. F. Volkova Abstract The alternating copolymer of divinyl ether and maleic anhydride (DIVEMA) possesses diverse biological activity and uses for production of drug delivery systems. DIVEMA's biological effects are determined by molecular mass, therefore it is necessary to have information about copolymer molecular mass and its distribution. A direct method for gel permeation chromatography analysis of DIVEMA molecular mass characteristics in aqua solution without any preliminary modification was developed. The effect of a number of factors (the concentration of monomers and their ratios, the concentration of initiator, the nature of the solvents) on DIVEMA's solution properties and molecular mass distribution was studied by gel permeation chromatography and viscometry. The approach to synthesis of DIVEMA with narrow molecular mass distribution was designed. The substantial influence of water on DIVEMA molecular mass characteristics was determined. The proposal was made that water may play a part in the formation of charge-transfer complexes playing a significant role in copolymerization. Copyright © 2003 John Wiley & Sons, Ltd. [source] Hidden pathogens uncovered: metagenomic analysis of urinary tract infectionsANDROLOGIA, Issue 2 2008C. Imirzalioglu Summary Urinary tract infections (UTIs) are the most common kidney and urologic diseases in industrial nations and are usually caused through faecal contamination of the urinary tract. In this study, we have examined 1449 urine specimens both by culture and by PCR. The majority of UTIs examined were caused by Escherichia coli (35.15%), followed by miscellaneous bacteria (23.03%), and by Enterococcus faecalis (19.39%). A large fraction of fastidious and anaerobic bacteria (22.43%) was not detected under culture conditions but only by using PCR. This group of bacteria evade the standard culture conditions used in routine diagnostic laboratories examining urine specimens. The molecular approach used broad-range 16S rDNA PCR, denaturing high-performance liquid chromatography analysis, sequencing, and bioinformatic analysis to uncover these ,hidden' pathogens and is recommended in particular when examining leukocyte esterase-positive and culture-negative urinary tract specimens. [source] Optimizing acidic methanolysis of poly(3-hydroxyalkanoates) in gas chromatography analysisASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 4 2009Chi-Wei Lo Abstract This work was undertaken to develop an improved gas chromatography (GC) analysis of poly (3-hydroxyalkanoate) (PHA) quantification method based on acidic methanolysis. This is achieved by investigating the kinetics of acidic hydrolysis of PHAs with sulfuric acid in the chloroform/aqueous solution to identify suitable hydrolytic pretreatment conditions for quantitative analysis of PHAs. The target parameters included sulfuric acid concentration, salt (NaCl) addition, kind of PHAs (commercial products of poly-3-hydroxybutyrate (PHB), poly(3-hydroxybutyrate- co -3-hydroxyvalerate) (PHBV-8%) and poly(3-hydroxybutyrate- co -3-hydroxyhexanoate) (PHBHHx-3.8% and-10.5%), as well as the type of PHA-producing microorganisms (Cupriavidus taiwanensis 184 and Burkholderia sp. PTU9). These results show that esters would preferentially accumulate in the organic phase when NaCl was added in the two-phase system, thereby enhancing the accuracy of GC analysis. Decomposition efficiency of different types of PHAs was found to be dependent on sulfuric acid concentration, such as 1% H2SO4 was favorable for PHB decomposition, while 5 and 7% H2SO4 should be used to decompose PHBV and PHBHHx. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Development and validation of a high-performance liquid chromatography method for the simultaneous determination of aspirin and folic acid from nano-particulate systemsBIOMEDICAL CHROMATOGRAPHY, Issue 9 2010Abhishek Chaudhary Abstract Attention has shifted from the treatment of colorectal cancer (CRC) to chemoprevention using aspirin and folic acid as agents capable of preventing the onset of colon cancer. However, no sensitive analytical method exists to simultaneously quantify the two drugs when released from polymer-based nanoparticles. Thus, a rapid, highly sensitive method of high-performance liquid chromatography analysis to simultaneously detect low quantities of aspirin (hydrolyzed to salicylic acid, the active moiety) and folic acid released from biodegradable polylactide-co-glycolide (PLGA) copolymer nanoparticles was developed. Analysis was done on a reversed-phase C18 column using a photodiode array detector at wavelengths of 233,nm (salicylic acid) and 277,nm (folic acid). The mobile phase consisted of acetonitrile,0.1% trifluoroacetic acid mixture programmed for a 30,min gradient elution analysis. In the range of 0.1,100,,g/mL, the assay showed good linearity for salicylic acid (R2 = 0.9996) and folic acid (R2 = 0.9998). The method demonstrated good reproducibility, intra- and inter-day precision and accuracy (99.67, 100.1%) and low values of detection (0.03, 0.01,,g/mL) and quantitation (0.1 and 0.05,,g/mL) for salicylic acid and folic acid, respectively. The suitability of the method was demonstrated by simultaneously determining salicylic acid and folic acid released from PLGA nanoparticles. Copyright © 2009 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||