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PubMed2000

Chromatographic aspects in high throughput liquid chromatography/mass spectrometry.

Important parameters to consider when developing a liquid chromatography/mass spectrometry (LC/MS) method are buffer type and concentration, and column geometry. In the work presented here the choice of buffer for the analysis of basic compounds using a polar embedded phase (HyPURITYtrade mark ADVANCE) is illustrated for the analysis of tricyclic antidepressants. Method transfer from a 4.6 mm i.d. column to a 2.1 mm i.d. column is demonstrated for the analysis of triazines and anabolic steroids and their metabolites, with no change in selectivity and with added speed of analysis. Analysis of eight beta-blockers is achieved in 65 seconds by using a short 30 x 4.6 mm C18 column.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Dye-affinity techniques for bioprocessing: recent developments.

Textile or triazine dyes play an important role as affinity ligands in protein purification. Each step of the protein purification protocol can be divided into three stages, partitioning between two phases, separation of these phases and recovery of the target protein from the enriched phase. Now developments in dye-affinity techniques are discussed emphasizing the innovations in all three stages of the protein purification process. Dye-affinity chromatography has become a routine step in protein purification. New dyes have been developed and used successfully in both traditional chromatographic mode and new modes like affinity precipitation, polymer aqueous two-phase partitioning or expanded bed chromatography. The specificity of dye techniques has been increased by both purposeful designing of new dyes and decreasing non-specific protein-dye interactions with polymer shielding. One can envisage further development and ramification of dye-affinity techniques in protein purification.

Affinity Labels↗
PubMed2000

Characterization of the pore structure of aqueous three-dimensional polyacrylamide gels with a novel cross-linker.

The properties of polyacrylamide hydrogels synthesized with a novel hexafunctional (three double bonds) cross-linker, hexahydro-1,3,5-triacryloyl-s-triazine (1a), was evaluated and compared to the currently used tetrafunctional (two double bonds) cross-linker N,N-methylenebisacrylamide (Bis). A variety of characterization techniques that require very little sample preparation and data handling were chosen and include polymerization temperature profiles and conversions, water swelling, differential scanning calorimetry (DSC), polyacrylamide gel electrophoresis (PAGE), Gradiflow electrophoretic separation process and scanning electron microscopy (SEM). The alternative use of 1a compared to Bis results in polyacrylamide gels with larger pore sizes and a broad pore size distribution.

Acrylic Resins↗
PubMed1983

Identification of metabolites of hexazinone by mass spectrometry.

The metabolites of hexazinone [3-cyclohexyl-6-(dimethylamino)-1-methyl-1,3,5-triazine-2,4(1H,3H)-dione ] obtained in the rat and in plants were identified by mass spectrometry. Rat urine metabolites were identified from direct probe spectra obtained on metabolites separated by thin-layer chromatography. Sugarcane metabolites were identified by gas chromatography mass spectrometry of the trimethylsilyl derivatives. The major metabolic routes were found to be hydroxylation of the cyclohexyl group and demethylation. All identifications were confirmed by synthesis and direct comparison of chromatographic data and mass spectra. Hexazinone is metabolized quickly and extensively in the biological systems studied, and is relatively nonpersistent in the environment.

Animals↗
PubMed2003

A bifunctional platinum(II) complex capable of intercalation and hydrogen-bonding interactions with DNA: binding studies and cytotoxicity.

The interactions of [Pt(CNN)(4-dpt)]PF(6), (1; 4-dpt=2,4-diamino-6-(4-pyridyl)-1,3,5-triazine, HCNN=6-phenyl-2,2'-bipyridine) with double-stranded DNA, poly(dA-dT)(2), and poly(dG-dC)(2) were examined by spectroscopic, electrophoretic, and hydrodynamic methods. The spectroscopic data were analyzed with McGhee, van't Hoff, and Gibbs-Helmholtz equations. In a comparative study, [Pt(CNN)(py)]PF(6) (2; py=pyridine) was prepared and the nature of its binding towards DNA was investigated [preliminary results: ChemBioChem 2003, 4, 62-68]. For reactions with calf thymus DNA at 20 degrees C, the intrinsic binding constants for 1 and 2 are (4.6+/-0.2)x10(5) and (2.3+/-0.3)x10(4) mol(-1) dm(3), respectively. Results of DNA-binding reactions revealed that 1 and 2 preferentially bind to the AT sequence of duplex DNA. Intercalation is the preferred binding mode for 2, whereas both intercalation and minor-groove binding are observed for 1. Complex 1 is cytotoxic against a number of carcinoma cell lines, including KB-3-1, CNE-3, and HepG2, and remains potent against multidrug- or cisplatin-resistant KB-V-1 and CNE1 cell lines, for which the resistance ratios are 1.6 and 1.5, respectively. Importantly, 1 is almost an order of magnitude less toxic to the normal cell line CCD-19Lu (IC(50)=176+/-1.7 microM) and it selectively induced apoptosis leading to cancer cell death with less than 5 % detectable necrosis.

Animals↗
PubMed2003

Macrocycles from perhalogenated heterocycles.

Perhalogenated heteroaromatic systems, such as trichloro-s-triazine and pentafluoropyridine, are multifunctional "building blocks" that react with a number of appropriate difunctional nucleophiles to provide access to a variety of macrocyclic and even cage-like molecular architectures. Unusual structural and complexation characteristics of the systems reported so far, such as the recognition of anions, provide a further stimulus for the development of this area.

Bridged-Ring Compounds↗
PubMed1994

Effect of cytochrome P-450 1A induction on enantioselective metabolism and pharmacokinetics of an aryltrifluoromethyl sulfide in the rat.

The pharmacokinetics of the antiparasitic drug toltrazuril (1-methyl-3-[3-methyl-4-[4-[trifluoromethyl]thio]phenoxy]phenyl- 1,3,5-triazine-2,4,6(1H,3H,5H)-trione) were studied in the rat following pretreatment with 3-methylcholanthrene, an inducer of rat liver cytochrome P-450 1A. The induction markedly modified the pharmacokinetics of the compound, leading to a decrease in the AUC value for toltrazuril sulfoxide. The results were explained on the basis of previous results from our laboratory relating to the product enantioselectivity of the formation of the sulfoxide and the substrate enantioselectivity of the subsequent formation of the sulfone.

Animals↗
PubMed2004

A beveled tip sheath liquid interface for capillary electrophoresis-electrospray ionization-mass spectrometry.

A simple and durable sheath liquid interface for capillary zone electrophoresis-electrospray ionization-mass spectrometry (CZE-ESI-MS) has been developed. This interface utilized a beveled tip emitter and was found to be more sensitive than the conventional sheath liquid interface. The use of a beveled tip reduces the optimal flow rate and therefore decreases sample dilution. The interface utilized a 380 microm inner diameter and 400 microm outer diameter beveled tapered tip. Because of the large inner diameter and outer diameter of the tip, the interface is robust and can be easily implemented. The performance of this interface for CZE-ESI-MS and micelle electrokinetic capillary electrophoresis-electrospray-mass spectrometry, as demonstrated by the analysis of synthetic drugs and triazine mixtures, was significantly better than results obtained using a conventional sheath liquid interface.

Electrophoresis, Capillary↗
PubMed2002

Raman and IR studies on adsorption behavior of adhesive monomers in a metal primer for Au, Ag, Cu, and Cr surfaces.

6-[N-(4-vinylbenzyl)propylamino]-1,3,5-triazine-2,4-dithione (VBATDT) and 10-methacryloyloxydecyl dihydrogen phosphate (M10P) are functional monomers used for the surface treatment of dental alloys. The aim of our study was to clarify the role of a commercial metal primer containing both the monomers in adhesion between resin and various dental metals on a molecular level. We used surface-enhanced Raman scattering (SERS) and infrared reflection absorption (IRA) spectroscopy. An SERS measurement was performed with a 647 nm laser line for a mixture of aqueous Au colloid and the primer. IRA spectra were taken for cast films of the primer on Au, Ag, Cu, and Cr surfaces as a function of rinse time, and for self-assembled monolayer (SAM) films from dilute mixed solution of VBATDT and M10P. These spectra indicate that VBATDT in the primer is mainly chemisorbed on Au, Ag, and Cu surfaces with respect to thickness, whereas only M10P is adsorbed on Cr. We also examined the tensile bond strengths between resin and Au, Ag, Cu, and Cr plates treated by VBATDT, with and without M10P, and found that VBATDT effectively promotes the bond strength between resin and the metals except for Cr, whereas M10P is effective only for Cr. These adhesion characteristics are consistent with the chemisorbed species on each metal surface as shown in the spectroscopic evidence.

Adhesives↗
PubMedDate not supplied

The design, synthesis and evaluation of affinity ligands for prion proteins.

Bifunctional affinity ligands based on a triazine scaffold were rationally designed to target prion protein and shown to bind recombinant prion protein with high affinity and selectivity. The ligands were capable of discriminating between prion protein glycoforms and monomeric and dimeric forms of the prion protein. The ligands also discriminate between conformational differences in the prion protein, resulting from point mutations in the prion protein gene. These results suggest that derived compounds could be used selectively to detect the disease-associated form of the prion protein, and as such, could provide diagnostic or therapeutic tools for prion diseases.

Animals↗
PubMed2004

Optimization of a solid-phase microextraction procedure for the determination of herbicides by micellar electrokinetic chromatography.

The use of a different optimization procedure that involves Experimental Design (ED) and Artificial Neural Networks (ANN) for the off-line coupling solid-phase microextraction-micellar electokinetic chomatography (SPME-MEKC) is presented. This combination of ED and ANN, mathematical tools not previously used in SPME-MEKC optimization, allowed us to obtain good extraction efficiencies in the SPME procedure for the determination of a group of eleven triazine herbicides in groundwater samples. Both extraction and desorption steps were carried out by solution stirring at 900 rpm. Optimal conditions for the off-line SPME procedure were: extraction with a poly(dimethylsiloxane)/divinylbenzene SPME fiber for 120 min, 10% (w/v) NaCl, desorption time 40 min, and 70% (v/v) of methanol/buffer as desorption mixture. Detection limits lay between 0.80 microg L(-1) and 4.89 microg L(-1). Finally, the optimized method was applied to the determination of these compounds in spiked and non-spiked groundwater samples using a previously optimized MEKC separation.

Chromatography↗
PubMed2005

Solid phase microextraction ion mobility spectrometer interface for explosive and taggant detection.

Ion mobility spectrometry (IMS) is a rugged, inexpensive, sensitive, field portable technique for the detection of organic compounds. It is widely employed in ports of entry and by the military as a particle detector for explosives and drugs of abuse. Solid phase microextraction (SPME) is an effective extraction technique that has been successfully employed in the field for the pre-concentration of a variety of compounds. Many organic high explosives do not have a high enough vapor pressure for effective vapor sampling. However, these explosives and their commercial explosive mixtures have characteristic volatile components detectable in their headspace. In addition, taggants are added to explosives to aid in detection through headspace sampling. SPME can easily extract these compounds from the headspace for IMS vapor detection. An interface that couples SPME to IMS was constructed and evaluated for the detection of the following detection taggants: 2-nitrotoluene (2-NT), 4-nitrotoluene (4-NT), and 2,3-dimethyl-2,3-dinitrobutane (DMNB). The interface was also evaluated for the following common explosives: smokeless powder (nitrocellulose, NC), 2,4-dinitrotoluene (2,4-DNT), 2,6-dinitrotoluene (2,6-DNT), 2,4,6-trinitrotoluene (2,4,6-TNT), hexahydro-1,3,5-trinitro-s-triazine (RDX), and pentaerythritol tetranitrate (PETN). This is the first peer reviewed report of a SPME-IMS system that is shown to extract volatile constituent chemicals and detection taggants in explosives from a headspace for subsequent detection in a simple, rapid, sensitive, and inexpensive manner.

Butanes↗
PubMed2005

A psbA mutation in Kochia scoparia (L) Schrad from railroad rights-of-way with resistance to diuron, tebuthiuron and metribuzin.

Kochia [Kochia scoparia (L) Schrad] has become resistant to many herbicides used in cropland and railroad rights-of-way in North Dakota and Minnesota. Kochia scoparia plants that had survived annual treatments with diuron and tebuthiuron were sampled along railroad rights-of-way in North Dakota and Minnesota. The samples were screened in the greenhouse for resistance to diuron, tebuthiuron, metribuzin and bromoxynil from 0.5x to 32x the recommended use rates. A resistant K scoparia accession (MN-3R) was confirmed with resistance up to 16-fold higher than recommended use rates for tebuthiuron and diuron and up to 4-fold higher for metribuzin. However, the resistant K scoparia accession was susceptible to bromoxynil even at 50% of the recommended use rate. The herbicide binding region of the psbA gene fragment of eight resistant (R) and seven susceptible (S) K scoparia accessions was PCR-amplified and sequenced for detection of mutations. The psbA gene of four R K scoparia accessions was mutated at residue 219 with substitution of isoleucine for valine (GenBank accession number AY251265). The seven S K scoparia accession sequences were wild-type at this residue (GenBank accession number AY251266). The other four R accessions sequences showed a previously known triazine R mutation with substitution of glycine for serine at residue 264. All 15 K scoparia accessions were wild-type at all other psbA residues within the region analyzed. Resistance to diuron, tebuthiuron and metribuzin among the railroad rights-of-way K scoparia is probably due to the mutation at residue 219 of the psbA gene in some plants, but due to the previously reported Ser(264)Gly substitution in other plants. Target-site resistance associated with a change of valine to isoleucine at residue 219 of the psbA target-site in weeds has previously been reported for Poa annua L selected in diuron-treated grass seed fields, and for Amaranthus powelli S Wats selected in linuron-treated carrot fields. This is the first report of the mutation in herbicide-resistant K scoparia.

Animals↗
PubMed2006

Metribuzin mobility in soil columns as affected by urea fertiliser.

Application of urea fertilisers to soils influences the soil solution characteristics and thus may affect the sorption of soil-applied herbicides. The present investigation reports the influence of urea co-application on sorption and leaching of metribuzin, a triazine herbicide. Urea application at 60 and 120 kg N ha(-1) increased metribuzin sorption in soils over that in untreated natural soil. The Kf (Freundlich adsorption coefficient) values of metribuzin for natural, 60 and 120 kg N ha(-1) treatments were 0.43, 0.46 and 0.84 microg(1 - 1/n) g(-1) ml1/n respectively. Downward mobility of metribuzin was studied in packed soil columns (300 mm length x 59 mm i.d.) at two irrigation intensities, 720 m3 ha(-1) (72 mm) and 3600 m3 ha(-1) (360 mm). After 720 m3 ha(-1) irrigation, metribuzin did not leach out of any column and was not detected in the leachate. Urea amendment slowed the leaching of metribuzin by 20 and 40% in 60 and 120 kg N ha(-1) urea-treated columns respectively. Also, following urea application, greater amounts of metribuzin were retained in the application zone. Upon increasing the irrigation intensity fivefold, urea application did not have any effect on metribuzin mobility, and its breakthrough from both natural and urea-amended columns occurred after 126 mm irrigation. However, there was a marked difference in the maximum concentration of metribuzin in the breakthrough curves obtained from natural and urea-amended columns. The study indicated that co-application of metribuzin and urea fertiliser is a safe practice as far as leaching of herbicide is concerned.

Adsorption↗
PubMed2002

Photocatalytic degradation of pesticides and bio-molecules in water.

Two approaches are suggested for the acceleration of the photocatalytic oxidation of organic contaminants of water: acceleration by oxidants and photo-enhancement by dyes. These processes were examined with several substances: two widely applied herbicides, bromacil (a uracil) and metribuzin (a triazine), and three proteins, studied as models of biocontaminated waters. The effects of oxygen and hydrogen peroxide indicated two different reaction patterns of photo-oxidation of the herbicides. With metribuzin, oxygen had a pronounced effect on the rate of photo-oxidation, while the influence of hydrogen peroxide was quite moderate; with bromacil, oxygen had a limited effect on the rate of photo-oxidation, which however was considerably enhanced by hydrogen peroxide. Acceleration of the photo-catalytic oxidation of colourless refractory contaminants by photo-excited dye was observed. Both UV and visible light were required for the enhanced decomposition. The mechanism of the reaction seems to involve a combination of oxidation by hydroxyl radicals, via the hole-electron semiconductor route, with subsequent oxidation of photo-intermediates by singlet oxygen formed by dye sensitization. The TiO2-photocatalyzed oxidation of proteins (albumin, ovalbumin and gamma-globulin) showed the susceptibility of proteins to photocleavage and of the amino acids to photocatalytic degradation. Tyrosine was the most sensitive, while the degradation of the aliphatic amino acids Gly and Asp was slow.

Albumins↗
PubMedDate not supplied

Herbicide resistance work in the United States Department of Agriculture-Agricultural Research Service.

Herbicide-resistant weed biotypes are an increasing problem in agriculture, with reports of resistance to almost every herbicide class at some place in the world, and the total number of resistant biotypes at over 250. Agricultural Research Service (ARS) scientists have been key players in this area since the first substantiated occurrence of these resistant biotypes in the 1970s. The most significant of their contributions is the complete unraveling of the mechanism of triazine resistance by Arntzen and colleagues, then with ARS at the University of Illinois. These studies established a high benchmark for research in this area and are a model for all studies in this area. Other ARS scientists have investigated a large number of weed biotypes with resistance to a wide range of herbicide classes and mechanisms of resistance. Collectively, these studies have been used to generate herbicide resistance-management schemes for growers, based upon the herbicide site and the potential for resistance development.

Agriculture↗
PubMed1995

The interaction of Candida boidinii formate dehydrogenase with a new family of chimeric biomimetic dye-ligands.

Seven chimeric biomimetic dye-ligands (BM) are purpose-designed and synthesized by specific structural modification of the parent anthraquinone dichlorotriazine dye Vilmafix blue A-R (VBAR). Each BM dye is composed of two enzyme-recognition moieties. The terminal biomimetic moiety bears a variable carboxylated structure linked to the triazine ring, thus mimicking the substrate of formate dehydrogenase (FDH). The anthraquinone moiety remains the same as that of the parent dye and recognizes the nucleotide-binding area of the target enzyme. Dyes are purified by liquid column chromatography (typically 99%), analyzed by liquid-paper chromatography, thin-layer chromatography, and high-performance liquid chromatography, and their lambda max and epsilon values are determined. The ability of dyes to act as affinity ligands versus Candida boidinii FDH is evaluated by kinetic studies and determining KD values from both difference spectra and enzyme inactivation studies. The parent dichlorotriazine dye VBAR binds specifically and irreversibly to FDH (k3 0.19 min-1; KD 19.3 microM). The inactivation of the NAD(+)-dependent enzyme by VBAR is competitively inhibited by NAD+, NADH, and ADP. Quantitatively inhibited FDH contained approx 1 mol of dye per mole of active site. The inhibition is irreversible and activity cannot be recovered either on incubation with 10 mM each of NAD+, NADH, and ADP or by extensive dialysis or gel filtration chromatography. The monochlorotriazine BM dyes do not inactivate FDH but inhibit competitively the inactivation by VBAR. When compared to VBAR and Cibacron blue 3GA (CB3GA), all BM dye-ligands exhibited lower KD values. FDH generally preferred binding to BM ligands which bore an aromatic terminal biomimetic moiety substituted with a monocarboxyl group rather than an alpha-ketoacid. Dye binding to FDH is accompanied by a characteristic spectral change in the range 550-800 nm. This phenomenon is perturbed after titration by increasing amounts of NAD+. Electrostatic interactions appeared to play a dominant role in the dye.FDH complex. The BM dye-ligand bearing a m-aminobenzoate at its terminal biomimetic moiety (BM1) exhibited the highest affinity (KD 1.6 microM, 8.0-fold decrease over CB3GA). BM1 differentiated between the binding sites of FDH, displaying uncompetitive inhibition with respect to NAD+ (Ki 15.6 microM) and competitive with respect to formate (Ki 18.1 microM).

Adenosine Diphosphate↗
PubMed1995

Mitochondrial calcium uptake stimulated by Cibacron blue F3GA in bovine sperm.

The triazine dye Cibacron Blue F3GA stimulated calcium uptake into an ionomycin-sensitive compartment of washed bovine sperm. Cibacron blue-stimulated uptake was not sensitive to nifedipine, diltiazem, or verapamil, but was blocked by transition metals, 1 microM ruthenium red, rotenone, and the protonophore CCCP. Uptake was dependent on the maintenance of energized mitochondria but not on oxidative or substrate level ATP production and was not supported by glycolysis. The cibarcon blue-stimulated uptake was judged by these criteria to be mitochondrial. Uptake in the absence of Cibacron blue was 0.046 +/- 0.008 and 0.268 +/- 0.068 nmol/min/10(8) cells with 0.1 mM Cibacron blue at 15 microM Ca2+. Half-maximal stimulation occurred at 20-25 microM Cibacron blue. Cibacron blue also allowed efflux of mitochondrial calcium in the presence of external calcium. This efflux would be blocked by ruthenium red, Ni2+, and La3+, but not by Co2+, which effectively blocked Cibacron blue-stimulated influx. Permeabilizing the plasma membrane with filipin indicated that Cibacron blue stimulation of mitochondrial calcium uptake operates directly on the mitochondria. Cibacron blue does not stimulate mitochondrial respiration and thus, calcium uptake was not the result of increased mitochondrial flux.

Adenosine Triphosphate↗