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Query: UMLS:C0040822 (tremor)
 18,428 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Removal of phthalate esters (PAEs) by alpha-cyclodextrin (CD)-linked chitosan bead in aqueous solution was studied. Results of kinetic experiments indicated that diheptyl phthalate (DHpP) was adsorbed most efficiently (3.21 mg/g) among the six PAEs. DHpP recovery was 94.6% from alpha-CD-linked chitosan bead by shaking both with a mixture of methanol and water (v/v = 8/2). The recovered alpha-CD chitosan bead was reusable as an adsorbent 20 times in the batch tests. The adsorbed PAE by alpha-CD-linked chitosan bead decreased as temperature increased. However, coexisting pH, NaCl, and Ca2+ did not affect adsorption efficiency. It was concluded that the application of low cost alpha-CD-linked chitosan bead could have the potential to effectively remove PAEs from different aquatic environments.
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PMID:Removal of phthalate esters by alpha-cyclodextrin-linked chitosan bead. 1707 38

A liquid chromatography (LC)/fluorescence procedure was validated for emamectin (EM B1a) and desmethylamino-emamectin (DMAEM B1a) residues in lobster tissue. They were extracted by shaking and sonicating with 1% ammonium acetate-methanol in the presence of sand. The extract was concentrated, partitioned with ethyl acetate, and cleaned up on a propylsulfonic cation exchange cartridge. The analytes were eluted from the cartridge with 5% ammonium hydroxide-methyl acetate, the eluate was concentrated, and the solvent was changed to dry 20% ethyl acetate-acetonitrile before derivatization with trifluoroacetic anhydride-N-methylimidizole. The products were analyzed by LC-fluorescence, and no interference [>limit of detection (LOD)] was detected in the control samples. Lobster tissues fortified with EM B1a and DMAEM B1a at 0.5, 5, 10, 25, and 50 ng/g gave overall mean recoveries of 96.7 +/- 12.4%, relative standard deviation (RSD) = 12.8% for EM B1 and 83.6 +/- 12.1%, RSD = 14.5% for DMAEM B1a. Regression analysis of the calibration data gave slopes of 0.90 (EM B1a) and 0.71 (DMAEM B1a) with an r2 = 0.99 for both compounds. The calculated LOD and limit of quantification (LOQ) for EM B1a were 1.10 and 3.32 ng/g, respectively, and for DMAEM B1a were 0.762 and 2.31 ng/g, respectively. Residues of EM B1a and DMAEM B1a in fortified lobster tissues stored at -20 degrees C showed that residues were stable for 10-12 months. No loss of EM B1a and DMAEM B1a residues was observed after 3 freeze/thaw cycles of fortified tissue in a 5-day period.
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PMID:Liquid chromatography/fluorescence method for emamectin B1a and desmethylamino-emamectin B1a residues in lobster tissue. 1722 16

MyoD, expressed in skeletal muscle lineages of vertebrate embryo, is one of muscle-specific basic helix-loop-helix (bHLH) transcription factors, which plays a key role in the determination and differentiation of all skeletal muscle lineages. In this study, a cDNA of grass carp MyoD was cloned and characterized from total RNA of grass carp embryos by RT-PCR. The full-length cDNA of grass carp MyoD is 1597 bp. The cDNA sequence analysis reveals an open reading frame of 825 bp coding for a protein of 275 amino acids, which includes a bHLH domain composed of basic domain (1-84(th) amino acids) and HLH domain (98-142(th) amino acids), without signal peptide. Then the MyoD cDNA of grass carp was cloned to yeast expression vector pPICZalphaA and transformed into P. pastoris GS115 strain, the recombinant MyoD protein with a molecular weight of about 31KD was obtained after inducing for 2d with 0.5% methanol in pH 8.0 BMGY medium, and the maximum yield was about 250 mg/L in shaking-flask fermentation. The results were expected to benefit for further studies on the crystal structure and physiological function of fish MyoD.
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PMID:Molecular cloning and expression of grass carp MyoD in yeast Pichia pastoris. 1724 78

How to effectively mix small volumes of liquids within microplate wells is a still underestimated and often neglected challenge. The method the authors introduce here relies on violent turbulent motion within a liquid caused by spotting an organic solvent drop onto its surface. The amount needed, less than 1 to 3 microL, is generally small enough not to alter bioactive molecules. Moreover, a solvent may be selected for its compatibility with assay components. The method was tested with layers of aqueous liquids that differ in pH and concentration of a pH-dependent dye, allowing mixing to be monitored optically. Rapid mixing was caused by spotting drops of alcohols, acetone, acetonitrile, and aqueous solutions of these, as long as the difference of surface tension between the drop and the uppermost layer of the bulk liquid surpassed 30 dynes/cm. Along with this difference, position and velocity of spotting, as well as viscosity and geometry of the bulk liquid volume, may influence the turbulence evoked. No significant difference was found for the activity of aspartate aminotransferase, alanine aminotransferase, and alkaline phosphatase when measured after mixing by shaking and after mixing by spotting 1 microL of methanol onto assays within 96-well microplates.
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PMID:Turbo-mixing in microplates. 1725 92

Interferon-lambda (IFN-lambda) is a newly identified IFN family which belongs to the class II cytokines. The three members of this family represent antiviral activities like other IFNs. In the present study, recombinant human IFN-lambda1 (rhIFN-lambda1) was produced by using the methylotrophic yeast Pichia pastoris (P. pastoris) expression system. cDNAs encoding amino acids 23-200 or 20-200 of human IFN-lambda1 were cloned and joined to sequence encoding the leader region (prepro segment) of the precursor of Saccharomyces cerevisiae alpha-factor. The two hybrid genes were subcloned into yeast integrative vector pAO815 separately to construct expression plasmids bearing four tandem copies of IFN-lambda1 expression cassettes. The expression plasmids were then used to transform into P. pastoris strain GS115, resulting in recombinant strains GS115/IFNlambda1P and GS115/IFNlambda1G with Mut(+) or Mut(s) phenotype. rhIFN-lambda1 was secreted into the medium upon methanol induction. In GS115/IFNlambda1P, however, KEX2 cleavage for mature rhIFN-lambda1 generation was inhibited by a proline at [Formula: see text] and the products were different from anticipation. GS115/IFNlambda1G strain secreted two forms of mature rhIFN-lambda1 with the same N-terminal sequence and different molecular weight. Periodic acid-Schiff (PAS) staining indicated that these proteins were glycosylated. The yield of low-glycosylated rhIFN-lambda1 in GS115/IFNlambda1G strain was approximately 65 mg l(-1) in shaking flasks, representing around 57% of the total secreted proteins. rhIFN-lambda1 was purified by cation exchange chromatography and gel filtration. The purified rhIFN-lambda1 showed specific efficiency to activate signal transducer and activator of transcription 1 (STAT1) and STAT2 that was comparable to that of commercial IFNalpha2a.
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PMID:Expression, purification and characterization of human IFN-lambda1 in Pichia pastoris. 1734 9

A new solvent-free analytical procedure based on headspace solid-phase microextraction (SPME) coupled to gas chromatography employing an electron capture detector (GC/ECD) or alternatively a mass spectrometric detector (GC/MSD) has been developed for the determination of phthalic acid esters (dimethyl-[DMP], diethyl-[DEP], di-n-butyl-[DnBP], butylbenzyl-[BBP], di-2-ethylhexyl-[DEHP] and di-n-octyl [DnOP] phthalate) in vegetable oils. Four different fiber coatings were evaluated, among them polydimethylsiloxane with a thickness of 100 microm appeared to be the best choice for allowing extraction of the whole group of analytes. Various solvents were tested as sample matrix modification agents with the aim to facilitate the transfer of esters with low vapour pressure (DEHP and DnOP) from oil matrix into the headspace. The addition of methanol resulted in optimal set-up applicable for all phthalate esters. Temperature control and the way of sample stirring were recognized as critical points of the whole procedure. Primarily, because shaking rather than stirring of the sample is carried out using a CombiPal multipurpose sampler, the automation of the SPME method employing this instrument was found to be not fully suitable for efficient stripping of phthalates from the oil matrix into the sample headspace. Nevertheless, the optimized manual SPME method, encompassing GC/ECD or GC/MSD for the separation and detection of target analytes, offers a unique solution and showed acceptable performance characteristics: linear response in the range of 0.5-2 mg kg(-1) and repeatability expressed as R.S.D. between 14 and 23% at the spiking level of 2 mg kg(-1).
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PMID:Headspace solid-phase microextraction of phthalic acid esters from vegetable oil employing solvent based matrix modification. 1738 70

Na,K-ATPase is a crucial enzyme for ion homeostasis in human tissues. Different isozymes are produced by assembly of four alpha- and three beta-subunits. The expression of the alpha3/beta1 isozyme is confined to brain and heart. Its heterologous production has so far never been attempted in a lower eukaryote. In this work we explored whether the methylotrophic yeast Pichia pastoris is capable of expressing the alpha3/beta1 isoform of human Na,K-ATPase. cDNAs encoding the alpha(3) and the beta(1)-subunits were cloned under the control of the inducible promoter of Pichia pastoris alcohol oxidase 1. Pichia pastoris could express the single alpha3- and beta1-subunits and even coexpress them after methanol induction. beta1-subunit was produced as a major 44-kDa glycosylated polypeptide and alpha3 as a 110-kDa unglycosylated polypeptide. Expression at the plasma membrane was limited in shaking flask cultures but by cultivating P. pastoris cells in a fermenter there was a 10-fold increase of the number of ouabain binding sites per cell. The exported enzyme was estimated to be about 0.230 mg L(-1) at the end of a bioreactor run. Na,K-ATPase proved active and the dissociation constant of the recombinant enzyme-ouabain interaction was determined.
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PMID:Expression of the alpha3/beta1 isoform of human Na,K-ATPase in the methylotrophic yeast Pichia pastoris. 1741 70

To enhance the antibacterial ability of Magaininl-12, its N side was joined with an alkaline peptide named Hexapeptide( RRWQWR), which would make Magaininl-12 cling to the membrane of bacterial cells even tighter. According to the partiality codon of Pichia pastoris, a new hybrid antibacterial peptide Hex-Mag was designed based on the sequence of Hexapeptide and Magainin( 1-12). Synthesized through gene splicing by overlap extension, the hybrid gene was cloned into pPIC9 to construct the expression vector pPIC9-HM. After restriction enzyme analysis and purification, the pPIC9-HM was transformed into Pichia pastoris GS115. And the positive clones screened by the phenotype were induced by methanol. After optimized the requirements for the flask-shaking culture fermentation, the hybrid antibacterial peptide was expressed on high level. The new peptide, which has a weight of 2.3kDa, could remain its inhibition activity after treating for more than 3 hours in boiled water. Detected by agrose diffusion assay, Hex-Mag showed its broad-spectrum antibacterial abilities not only to Gram-negative bacteria but also to Gram-positive bacteria. The function of additive positive charges were testified by the antibacterial experiments, and the results showed the activity of Hex-Mag was stronger than that of Magainin1-12 obviously.
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PMID:[Cloning, expression and characterization of a new hybrid AMP gene of Hex-Mag]. 1743 36

Conditions were optimized for the simultaneous, alkaline, aqueous methanol extraction of aflatoxins (AFL), i.e., B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2), and ochratoxin A (OTA) with subsequent purification, isolation, and determination of the toxins in ginseng and ginger. Powdered roots were extracted with methanol-0.5% NaHCO3 solution (7 + 3). After shaking and centrifugation, the supernatant was diluted with 100 mM phosphate buffer containing 1% Tween 20 and filtered through glass microfiber filter paper. The filtrate was then passed through an immunoaffinity column, and the toxins were eluted with methanol. The AFL were separated and determined by reversed-phase liquid chromatography (RPLC) with fluorescence detection after postcolumn UV photochemical derivatization. OTA was separated and determined by RPLC with fluorescence detection. Recoveries of AFL added at 2-16 ng/g and OTA added at 1-8 ng/g to ginseng were 72-80 and 86-95%, respectively. Recoveries of AFL and OTA added to ginger were similar to those for ginseng. A total of 39 commercially available ginger products from 6 manufacturers were analyzed. Twenty-six samples were found to be contaminated with AFL at 1-31 ng/g and 29 samples, with OTA at 1-10 ng/g. Ten samples contained no AFL or OTA. Ten ginseng finished products were also analyzed; 3 contained AFL at 0.1 ng/g and 4 contained OTA at levels ranging from 0.4 to 1.8 ng/g. LC/tandem mass spectrometry with multiple-reaction monitoring of 3 collisionally induced product ions from the protonated molecular ions of OTA, AFB1, and AFG1 was used to confirm the identities of the toxins in extracts of the finished products.
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PMID:Use of multitoxin immunoaffinity columns for determination of aflatoxins and ochratoxin A in ginseng and ginger. 1776 Mar 42

A well-validated analytical method based on microwave-assisted extraction (MAE) and SPE is presented for the combined analysis of alachlor, alachlor-oxanilic acid (OXA), alachlor-ethanesulfonic acid (ESA), metolachlor, metolachlor-OXA, metolachlor-ESA residues in soils. Extraction of solutes by soil sample was carried out by MAE for 20 min at 100 degrees C in the presence of 50 mL solution (methanol/water 50:50), the extract was subsequently passed through C18 cartidges and fractionated into two fractions, the first with parent compounds (PCs) analyzed with GC-MS and the second one containing the metabolites analyzed with HPLC. For the SPE step, various types of sorbents (Environmental C18, tC18, Supelclean ENVI-carb, and LiChrolut EN) have been used, and their respective advantages and disadvantages are discussed. After the method optimization, average recovery values of all solutes were > 71% in the 50-500 microg/kg fortification range with RSD <10%. The LOQ and LOD were 10-50 and 5-10 microg/kg, respectively. The method was validated with two types of soils (1 and 2.4% organic matter) and in fresh (12 h aging), intermediate (1 wk aging), and aged (1 month aging) spiked samples. Moreover, residue levels determined after field application of alachlor or metolachlor were higher when soils were processed using this method than with a comparison method based on an overnight flask shaking (FS) of soil suspension.
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PMID:Determination of alachlor, metolachlor, and their acidic metabolites in soils by microwave-assisted extraction (MAE) combined with solid phase extraction (SPE) coupled with GC-MS and HPLC-UV analysis. 1776 8


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