Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Triazines”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,801 records · Page 100Linked to original sources
PubMed1999

ZM 241385, an adenosine A(2A) receptor antagonist, inhibits hippocampal A(1) receptor responses.

4-(2-[7-amino-2-(2-furyl¿1,2,4¿-triazolo¿2,3a¿-¿1,3, 5¿triazin-5-yl-amino]ethyl)phenol (ZM 241385) has been used as an antagonist of adenosine A(2A) receptors, exhibiting high selectivity over adenosine A(1) receptors. We now report that ZM 241385 (10-50 nM) attenuated the inhibitory action of N(6)-cyclopentyladenosine (10 nM) and R(-)-N(6)-phenylisopropyladenosine (R-PIA, 20 nM), two selective adenosine A(1) receptor agonists, on hippocampal population spike amplitude. This effect is unlikely to be a direct antagonism of adenosine A(1) receptor since the K(i) of ZM 241385 to displace [3H]PIA (2 nM) binding, from hippocampal membranes ranged from 0.8 to 1.9 microM. These results question the usefulness of ZM 241385 to define adenosine A(2A) receptors actions in functional studies.

Animals↗
PubMed1985

Retinal damage in hatched chicks induced by formoguanamine. Decrease in ornithine aminotransferase activity and vitamin B6 content.

Subcutaneous injection of formoguanamine (2,4-diamino-s-triazine) induced sightlessness in newly hatched chicks within 28-32 hr. The specific activity of retinal ornithine aminotransferase, localized exclusively in the mitochondria of retinal pigment epithelium, and the retinal vitamin B6 content decreased rapidly after formoguanamine administration. An absorption spectrum of retinal extract showed reduced absorbance at 400 nm in the formoguanamine-treated chicks, but delta 1-pyrroline-5-carboxylate reductase, an enzyme in the retinal cytosol, did not change significantly. A drug-metabolizing enzyme, glutathione transferase, showed an increase in specific activity during a later phase. Histological examination of the formoguanamine-treated chicks revealed characteristic degeneration of pigment epithelium and photoreceptors, acute retinal detachment and a secondary gliosis in the outer nuclear layer. From these findings it may be concluded that formoguanamine primarily damages the physiological functions of retinal pigment epithelium and photoreceptors and results in irreversible retinal detachment in newly hatched chicks.

Animals↗
PubMed2000

Multiresidue method for the analysis of five antifouling agents in marine and coastal waters by gas chromatography-mass spectrometry with large-volume injection.

A simple multiresidue method has been developed for the determination of five pesticides, commonly used as active ingredients in antifouling paints, in seawater samples. The pesticides studied were: chlorothalonil (2,4,5,6-tetrachloroisophthalonitrile), dichlofluanid (N-dimethyl-N-phenylsulphamide), Sea-Nine 211 (4,5-dichloro-2-n-octyl-4-isothazolin-3-one), Irgarol 1051 (2-methylthio-4-tert.-butylamino-6-cyclopropylamino-s-triazine) and TCMTB (2-thiocyanomethylthiobenzothiazole). The analytes were extracted from 200 ml water samples, using solid-phase extraction. A copolymer with hydrophilic-lipophilic balance was used as sorbent yielding good recoveries (82-95%) for most compounds except dichlofluanid and Sea-Nine 211 (<60%). Large volume injection (10 microl) gas chromatography and electron impact ionization MS (selected ion monitoring mode) detection enabled these compounds to be identified and quantified at the 1.2-3.0 ng/l level. Analysis of samples performed in three marinas in Almería (Spain) revealed the presence of Irgarol 1051 in all the cases, at concentration levels between 25 and 450 ng/l.

Aniline Compounds↗
PubMed2001

Affinity chromatography of porcine pepsin on different types of immobilized 3,5-diiodo-L-tyrosine.

The preparation of affinity sorbents containing immobilized iodinated derivatives of L-tyrosine for the affinity chromatography of porcine pepsin is described. The ligand was coupled either to Sepharose 4B or bead cellulose after the divinylsulfone activation or to Sepharose 4B after the activation with 2,4,6-trichloro-1,3,5-triazine. The highest capacity for porcine pepsin was found in the case of 3,5-diiodo-L-tyrosine coupled to divinylsulfone-activated Sepharose.

Animals↗
PubMed2001

Low-temperature clean-up method for the determination of organophosphorus insecticides in olive oil.

A simple, extremely low-cost method using low-temperature lipid precipitation has been developed for the rapid analysis of virgin olive oil for organophosphorus insecticides and triazine herbicides commonly used in olive groves. The method gives good clean-up for GC analysis with nitrogen-phosphorus detection and recoveries between 77 and 104%, with RSD values of 7-16%. Matrix enhancement was observed for some pesticides and metabolites.

Chromatography, Gas↗
PubMed2001

Solid-phase extraction with styrene-divinylbenzene sorbent for high-performance liquid or gas chromatographic determination of urinary chloro- and methylthiotriazines.

A solid-phase extraction (SPE) procedure on a styrene-divinylbenzene (SDB-1 cartridge) for extraction and cleaning of the triazine herbicides atrazine, simazine, ametryn, and prometryn and atrazine monodealkylated metabolites from urine samples was developed and optimised for final high-performance liquid chromatographic (HPLC-UV diode array detection) and gas chromatographic (GC-electron-capture detection and GC-thermionic-sensitive detection) analyses. Interfering polar matrices were eliminated by rinsing SDB-1 with 1% acetonitrile in water or with pure water. Extraction recoveries were from 78 to 101% with an RSD of about 10% for all studied compounds. The extraction recovery for the didealkylated atrazine metabolite was significantly lower and this compound cannot be determined with these procedures. Sorbent matrix generated interferences, although not detected by the chromatographic system, lowered the response of nitrogen-phosphorus and electron-capture GC detectors for monodealkylated chlorotriazines when compared to standards prepared in n-hexane. HPLC and GC analysis with SPE (SDB-1) preconcentration showed excellent linearity over the concentration range tested, with detection limits in urine of 10 ng ml(-1) for the parent herbicides (HPLC and GC analysis) and 20 ng ml(-1) for monodealkylated chlorotriazines (HPLC analysis).

Chromatography, Gas↗
PubMed1991

Dye-ligand affinity partitioning of lactate dehydrogenase isoenzymes.

Aqueous two-phase systems consisting of dextran and polyethylene glycol (PEG) were used to study the partition behaviour of isoenzymes of lactate dehydrogenase (LDH; E.C. 1.1.1.27) from rabbit tissues in the presence and absence of a series of triazine dyes covalently coupled to PEG. The variations in the primary structures of LDH1(H4) and LDH5(M4) are reflected by significantly different partition coefficients. A class of dyes exhibiting defined structural elements is able to distinguish between both of these isoenzymes. This may be based on differences in the binding affinity to the catalytic site of the enzyme. The difference in the relative affinities of LDH1 and LDH5 to Procion Blue H-5R, as estimated by affinity partitioning, were corroborated by chromatographic experiments. Affinity partitioning in aqueous two-phase systems can be used to predict and to optimize conditions for the fast and simple chromatographic separation of isoenzymes.

Animals↗
PubMed1991

Use of thermospray liquid chromatography-mass spectrometry to aid in the identification of urinary metabolites of a novel antiepileptic drug, Lamotrigine.

The use of thermospray liquid chromatography-mass spectrometry allowed the structural elucidation of a number of urinary metabolites of Lamotrigine, 3,5-diamino-6-(2,3-dichlorophenyl)-1,2,4-triazine, formed after administering the drug to man, Cynomolgus monkey and rabbit. This data when combined with the data obtained from high-performance liquid chromatography with radiochemical detection enabled us to determine the types and amounts of unchanged drug and metabolites excreted in urine by man and a number of laboratory animal species. This technique was particularly useful as it highlighted a previously unknown fact that Lamotrigine is metabolised to form two different N-glucuronides, one of which is resistant to cleavage in vitro by a crude beta-glucuronidase preparation from Helix pomatia.

Animals↗
PubMed1991

High-performance liquid chromatography of amino acids, peptides and proteins. CIX. Investigations on the relation between the ligand density of cibacron blue immobilized porous and non-porous sorbents and protein-binding capacities and association constants.

A porous silica of nominal 5 microns particle diameter and 30 nm pore size (Nucleosil 300-5) and a non-porous silica of nominal 1.5 microns particle diameter were activated with 3-mercaptopropyltriethoxysilane (MPTS), followed by the immobilization of the triazine dye, Cibacron Blue F3GA. Various biomimetic dye sorbents with graduated ligand densities between 1 mumol/m2 and 0.01 mumol/m2 were prepared. The capacities and the association constants associated with the binding of lysozyme to these sorbents were determined by frontal analysis experiments [J. Chromatogr., 476 (1989) 205-225]. Due to the ability of the Cibacron Blue F3GA-modified silicas to act as mixed mode coulombic and hydrophobic interaction sorbents and the highly charged nature of the surface structure of lysozyme (pl 11), two mobile phase conditions were examined. In one case a 0.1 M phosphate buffer, pH 7.8, was used as the equilibration and loading buffer, in the second case 1 M sodium chloride-0.1 M phosphate buffer, pH 7.8 was employed as the equilibration and loading buffer to monitor the influence of ionic interactions. The elution was performed in each case with a 2.5 M potassium thiocyanate solution. With the porous silica dye sorbents and 1 M NaCl present in the loading buffer, the highest capacity was achieved when Cibacron Blue F3GA was immobilised to the level of 0.1 mumol/m2. In the case of the non-porous silica dye sorbents, the maximum protein capacity was achieved when 0.5 mumol/m2 dye were immobilised onto the support. Evaluation of the frontal breakthrough curves confirmed that the kinetics of adsorption of lysozyme onto the non-porous sorbent were substantially faster than the adsorption of lysozyme onto the porous sorbent due to the absence of pore diffusion effects in case of the non-porous support. Furthermore, the adsorption of lysozyme on both sorbents was faster when no salt was added to the loading buffer, indicating that there is either conformational or reorientation effects operating during the specific binding of the protein to the dye ligand, or that the interaction is proceeding through the participation of a second class of binding sites. The magnitude of the association constants, Ka, for the lysozyme-Cibacron Blue F3GA systems were found to be dependent on the ligand density of the sorbent. With decreasing ligand density, the protein-ligand interaction became stronger, e.g. Ka values became larger. These results confirm earlier observations on the effect of ligand steric compression on the affinate-ligand association constant, e.g. the protein needs sufficient space to interact with the ligand in an optimum way.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acids↗
PubMed1986

Method for characterization of selectivity in reversed-phase liquid chromatography. III. Retention behaviour in gradient-elution chromatography: application to the chromatography of pesticide compounds.

The method introduced recently for the characterization and prediction of absolute and relative retention in reversed-phase liquid chromatography under isocratic conditions has been applied to gradient-elution chromatography. The method is based on two indices (one lipophilic, nce, and the other polar, qi, to characterize the behaviour of each solute in methanol-water mobile phases of various compositions. The indices nce and qi of phenylurea and triazine herbicides were found to be composed of additive contributions of structural elements (functional groups) in the molecules of the solutes. Using the present approach, it is possible to predict retention volumes in gradient-elution chromatography with a precision comparable to those under isocratic conditions (i.e., less than 10% relative for most compounds tested). Simultaneous adjustment of the initial mobile phase composition and the slope of the linear gradient makes it possible to control to a certain extent the selectivity in gradient-elution chromatography using binary solvent gradients and offers an alternative approach to the use of multi-solvent gradients for selectivity control. This method may be especially useful in optimizing gradient-elution separations of pairs of compounds with positive differences in both indices nce and qi, delta nce greater than 0 and delta q greater than 0. Selection of the optimal gradient profile is illustrated on a practical example of gradient-elution chromatography of phenylurea herbicides.

Chromatography, Liquid↗
PubMed2002

Detection of explosives and their degradation products in soil environments.

Polynitro organic explosives [hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT)] are typical labile environmental pollutants that can biotransform with soil indigenous microorganisms, photodegrade by sunlight and migrate through subsurface soil to cause groundwater contamination. To be able to determine the type and concentration of explosives and their (bio)transformation products in different soil environments, a comprehensive analytical methodology of sample preparation, separation and detection is thus required. The present paper describes the use of supercritical carbon dioxide (SC-CO2), acetonitrile (MeCN) (US Environmental Protection Agency Method 8330) and solid-phase microextraction (SPME) for the extraction of explosives and their degradation products from various water, soil and plant tissue samples for subsequent analysis by either HPLC-UV, capillary electrophoresis (CE-UV) or GC-MS. Contaminated surface and subsurface soil and groundwater were collected from either a TNT manufacturing facility or an anti-tank firing range. Plant tissue samples were taken fromplants grown in anti-tank firing range soil in a greenhouse experiment. All tested soil and groundwater samples from the former TNT manufacturing plant were found to contain TNT and some of its amino reduced and partially denitrated products. Their concentrations as determined by SPME-GC-MS and LC-UV depended on the location of sampling at the site. In the case of plant tissues, SC-CO2 extraction followed by CE-UV analysis showed only the presence of HMX. The concentrations of HMX (<200 mg/kg) as determined by supercritical fluid extraction (SC-CO2)-CE-UV were comparable to those obtained by MeCN extraction, although the latter technique was found to be more efficient at higher concentrations (>300 mg/kg). Modifiers such as MeCN and water enhanced the SC-CO2 extractability of HMX from plant tissues.

Azocines↗
PubMed2003

Determination of herbicides and a metabolite in human urine by liquid chromatography-electrospray ionization mass spectrometry.

A method was developed to determine simazine, atrazine and their metabolite, 2-chloro-4,6-diamino-1,3,5-triazine, in urine. The presence of these herbicides in urine may reflect possible exposure to pesticides. Sample preparation involved protein precipitation and solid-phase extraction. The samples were analyzed by high-performance liquid chromatography-mass spectrometry. The detection limits were 0.4 microg/l and the analytes have a linear response in the interval 6-800 microg/l. The precision of the method was reflected in the RSD of < 2.4% for the herbicides studied. Based on the detectable herbicide levels from spiked urine samples collected from unexposed volunteers, this method can be used to determine the low levels necessary for establishing reference values of the selected herbicides and the metabolite.

Chromatography, Liquid↗
PubMed2003

Cyclodextrin-assisted capillary electrophoresis for determination of the cyclic nitramine explosives RDX, HMX and CL-20 comparison with high-performance liquid chromatography.

A sulfobutyl ether-beta-cyclodextrin-assisted electrokinetic chromatographic method was developed to rapidly resolve and detect the cyclic nitramine explosives 2,4,6,8,10,12-hexanitro-2,4,6,8,10,12-hexaaza-isowurtzitane (CL-20), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) and their related degradation intermediates in environmental samples. Development of the electrophoretic method required the measurement of the aqueous solubility of CL-20 which was determined to be 3.59 +/- 0.74 mg/l at 25 degrees C (95% confidence interval, n=3). The performance of the method was then compared to results obtained from existing high-performance liquid chromatography methods including US Environmental Protection Agency method 8330.

Aza Compounds↗
PubMed1997

Direct purification of lysozyme using continuous counter-current expanded bed adsorption.

We describe the application of a novel technique for the continuous counter-current chromatography of proteins. The unit operation has shown potential in extracting targeted species from unclarified feedstocks, delivering clarified streams of purified product. The adsorbent used in this equipment consists of a perfluorocarbon matrix, coated with poly(vinyl alcohol), and derivatized with the triazine dye Procion Red HE-7B. Purification of lysozyme from egg-whites and enriched bovine milk could be carried out continuously. The former was extracted in 90.5% yield at a rate of 7400 U/min, achieving a purification factor of 19.4. Lysozyme from the enriched milk sample was extracted continuously at a rate of 41000 U/min, in 66.0% yield. The continuous products streams in both cases were fully clarified, thus enabling their direct application to a final polishing step, if desired.

Animals↗
PubMed1997

Comparative studies on the isothermal characteristics of proteins adsorbed under batch equilibrium conditions to ion-exchange, immobilised metal ion affinity and dye affinity matrices with different ionic strength and temperature conditions.

In these investigations, the influence of a range of experimental parameters on the isothermal characteristics of hen egg white lysozyme (HEWL) and human serum albumin (HSA) adsorbed to several different adsorbents has been examined. The adsorbents were selected to encompass the same basic types of silica support matrices, but with the ligand properties and surface characteristics adjusted so that the dominant mode of interaction between the protein and the ligand involved either electrostatic binding (i.e. as ion-exchange interaction with polyaspartic acid immobilised onto glycidoxypropyl-modified Fractosil 1000), mixed-mode binding with both hydrophobic and electrostatic effect contributing to the protein-ligand interaction (i.e. as dye-affinity interactions with Cibacron Blue F3G-A immobilised onto Lichroprep DIOL or onto glycidoxypropyl-modified Fractosil 1000), or lone pair coordination binding (i.e. as immobilised metal ion affinity (IMAC) interactions with Cu2+ ions complexed with iminodiacetic acid immobilised onto glycidoxypropyl-modified Fractosil 1000). In each case, the adsorbents exhibited similar ligand densities and had the same particle size ranges and silica surface pretreatment. The effect of the ionic strength of the adsorption buffer and temperature on the isothermal adsorption behaviour under batch equilibrium binding conditions of the two test proteins were determined. Consistent with previous observations with soft gel ion exchangers and triazine dye-based adsorbents that are used in packed bed chromatographic systems, the capacities of the silica-based ion-exchange adsorbents, as well as the Cibacron Blue F3G-A dye affinity adsorbents, for both HSA and HEWL were reduced as the salt concentration was increased under batch equilibrium binding conditions. Moreover, with both of these classes of adsorbents, as the ionic strength was increased under constant temperature conditions, the isothermal adsorption dependencies progressively approximated more closely a Langmuirean model of independent binding site interactions, typical of a mono-layer binding process. In contrast, with the silica-based immobilised metal ion affinity adsorbents as the ionic strength was increased the adsorption behaviour appeared to follow a Freundlich model, indicative of positive cooperativity in the binding process. In parallel experiments, the effect of changes in temperature under iso-ionic strength conditions was examined. With increasing temperature, different patterns of isothermal adsorption behaviour for both test proteins were observed, with the magnitude of these trends depending on the type of interaction involved between the immobilised ligand and the protein. Utilising first order Van't Hoff relationships to analyse the experimental data for these protein-ligand interactions, the apparent changes in enthalpy and entropy for these interactions have been derived from the dependency of the change in the apparent Gibbs free energy on 1/T.

Adsorption↗
PubMed1998

Dye-ligand and metal chelate poly(2-hydroxyethylmethacrylate) membranes for affinity separation of proteins.

Cibacron Blue F3GA was covalently immobilized onto poly(2-hydroxyethyl methacrylate) pHEMA) membranes via the nucleophilic reaction between the chloride of its triazine ring and the hydroxyl group of pHEMA. Then, Fe3+ ions were complexed by chelation with the immobilized Cibacron Blue F3GA molecules. Different amounts of Fe3+ ions were loaded on the membranes by changing the concentration of Fe3+ ions and pH of the reaction medium. Membranes with or without Fe3+ were used in the adsorption of glucose oxidase, catalase and bovine serum albumin. The adsorption capacities of these membranes were determined by changing pH and the concentration of the proteins in the adsorption medium. The adsorption phenomena appeared to follow a typical Langmuir isotherm. The maximum capacities (qm) of the Fe3+ complexed membranes for glucose oxidase, catalase and bovine serum albumin (8.70 x 10(-3) mumol m-2, 2.15 x 10(-3) mumol m-2 and 2.21 x 10(-3) mumol m-2) were greater than those of the untreated membranes (6.79 x 10(-3) mumol m-2, 1.34 x 10(-3) mumol m-2 and 1.94 x 10(-3) mumol m-2) respectively. The nonspecific adsorption of the enzymes and the protein on the pHEMA membranes was negligible.

Catalase↗
PubMed1999

Analysis of atrazine, terbutylazine and their N-dealkylated chloro and hydroxy metabolites by solid-phase extraction and gas chromatography-mass spectrometry and capillary electrophoresis-ultraviolet detection.

Solid-phase extraction (SPE) with the styrene-divinylbenzene adsorbent LiChrolut EN was investigated for the extraction of the s-triazine herbicides atrazine and terbutylazine, their polar N-dealkylated degradation products deethylatrazine (DEA), deisopropylatrazine (DIA) and deethylterbutylazine (DET) and for the hydrophilic hydroxytriazine degradation products (HTDPs) hydroxyatrazine (HA), hydroxyterbutylazine (HT), deethylhydroxyatrazine (DEHA), deisopropylhydroxyatrazine (DIHA) and deethyldeisopropylhydroxyatrazine (ameline). The optimum pH value for the extraction of the HTDPs from fortified tap water at 2 micrograms/l is 3.0. Recovery values with 200 mg LiChrolut EN are > 80% for HA, HT, DEHA and 30% for DIHA from 200 ml spiked tap and river water. Atrazine, terbutylazine, DEA, DIA and DET are quantitatively extracted by LiChrolut EN. The chlorotriazines are analyzed by GC-MS and the HTDPs by capillary zone electrophoresis (CZE) and micellar electrokinetic capillary chromatography (MECC) with an acetate buffer at pH 4.6 or a sodium borate-sodium dodecyl sulfate buffer at pH 9.3. The combined method of SPE enrichment and CE analysis allows the determination of HTDPs in the low microgram/l range.

Atrazine↗
PubMed2000

Trace detection of explosives using a membrane-based displacement immunoassay.

A compact membrane-based displacement immunoassay has been designed for rapid detection of explosive compounds 2,4,6-trinitrotoluene (TNT) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) at high femtomole levels. The system consists of activated porous membranes, onto which either TNT or RDX antibodies are immobilized, that are inserted into microreactor columns, incorporated into a flow system. The assay is prepared by saturating the immobilized antibody binding sites with labeled antigen. Target analyte is introduced upstream of the microreactor, while the displacement of labeled antigen is monitored downstream using a fluorometer. The concentration of displaced labeled antigen detected is proportional to the concentration of the target analyte introduced into the system. This system provides a reusable and reagentless sensor, suitable for continuous monitoring of explosives, with an operating lifetime of over 50 positive samples. Multiple assays were performed in approximately 5 min at different flow rates, using membranes saturated with varying antibody concentrations. The membrane-based format exhibited a detection limit of approximately 450 fmol for TNT and RDX (100 microl of 1 ng/ml solution) in laboratory samples.

Antibodies, Monoclonal↗

Refine your search to explore more results.