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PubMed2004

Quantitative analysis of twelve sulfonamides in honey after acidic hydrolysis by high-performance liquid chromatography with post-column derivatization and fluorescence detection.

A quantitative HPLC-fluorescence method for the simultaneous determination of 12 sulfonamides (sulfaguanidine, sulfanilamide, sulfacetamide, sulfadiazine, sulfathiazole, sulfapyridine, sulfamerazine, sulfamether, sulfamethazine, sulfamethoxypyridazine, sulfachloropyridazine and sulfadoxine) in honey was developed and validated. Sample pretreatment included acidic hydrolysis, followed by liquid-liquid extraction and solid-phase extraction on a strong cation exchanger. LC separation was performed in 45 min, with a total analysis time of 60 min. Identification and quantitation were based on retention time and fluorescence intensity, respectively. Peak area ratios of the target analytes and the internal standard were fit to a linear least-squares regression curve with a weighting factor of 1/x. Limits of detection and quantitation (LOQ) had values of 1 or 2 and 2 or 5 ng/g, respectively. Linearity was obtained with an average coefficient of determination (R2) higher than 0.997, over a dynamic range from the LOQ value up to 100ng/g. The method demonstrated good intra- and interbatch precision and accuracy. No interferences with the peaks of interest were observed throughout the chromatographic run. Sample pretreatment provided efficient cleanup, while post-column derivatization with fluorescamine proved to be a reproducible derivatization technique enabling a sensitive and rugged quantitative determination of sulfonamides.

Chromatography, High Pressure Liquid↗
PubMed2005

Dispersive solid-phase extraction for the determination of sulfonamides in chicken muscle by liquid chromatography.

A new, fast and low-cost sample preparation for the determination of sulfonamide (SA) residues in chicken muscle by LC technique has been developed. The procedure involves single extraction of sample with acetonitrile, followed by a rapid clean-up and was called "dispersive solid-phase extraction" (dispersive SPE). Using dispersive SPE 25 mg of octadecyl sorbent was added to 1 ml of acetonitrile extract, mixed and centrifuged. The acetonitrile layer was evaporated and residue was dissolved in acetate buffer (pH 3.5). Analysed compounds were detected by fluorescence detector after pre-column derivatization with fluorescamine. The separation of analytes was performed with gradient elution with mobile phase methanol: 2% acetic acid and RP-LC analytical column. The whole procedure was evaluated for six sulfonamides (sulfadiazine, sulfamerazine, sulfamethazine, sulfametoxypirydazine, sulfametoxazole and sulfadimetoxine) according to the European Commission Decision 2002/657/EC. Specificity, decision limit (CCalpha), detection capacity (CCbeta), trueness and precision were determined during validation process. The dispersive SPE with octadecyl sorbent was found suitable for sample preparation before sulfonamide determination in chicken muscle. As it was found the most of endogenous matrix components were removed and the analytes were isolated from spiked samples with recoveries above 90%. The used analytical conditions allow to successively separate all the tested sulfonamides with the limit of detection at the level of 1-5 microg/kg. The method is simple, rapid and more effective than conventional methods.

Animals↗
PubMed2006

Rapid on-column analysis of glucosamine and its mutarotation by microchip capillary electrophoresis.

A novel electrophoretic microchip method for analyzing alpha- and beta-d-glucosamine and their interconversion in solution is presented. d-Glucosamine is labeled with fluorescamine and analyzed by capillary electrophoresis in under 2 min revealing its pH-dependent mutarotation between the alpha- and beta-anomers. The forward interconversion rates for the labeled sugars, based on an iterative analysis of the plateau heights between the peaks, are 0.72+/-0.09, 1.3+/-0.1, and 2.2+/-0.3 x 10(-3)s(-1) at pH 8.99, 9.51 and 10.01, respectively. In a separate experiment, the mutarotation of the unlabeled alpha-d-anomer was followed; the relative intensities of the alpha- and beta-peaks as a function of reaction time at pH 9.51 give a forward rate constant of 0.6+/-0.1 x 10(-3)s(-1). These results demonstrate that fast microchip separations, previously exploited for amine, amino acid, and nucleobase analysis, can also be used to analyze amino sugars and their mutarotation.

Electrophoresis, Microchip↗
PubMed2006

Regulation of transduction efficiency by pegylation of baculovirus vector in vitro and in vivo.

In this study, poly(ethylene glycol) (PEG) was coupled to baculovirus to regulate transduction efficiency of baculovirus in vitro and in vivo. The degree of pegylation in virions was measured by the loss of free amines via a fluorescamine-based assay. The efficiency of green fluorescent protein (GFP) expression was used to monitor transduction efficiency. As the results, the transduction efficiency in pegylated baculovirus was decreased with an increase of pegylation in baculovirus in vitro and in vivo. Interestingly, the transduction efficiency of the pegylated baculovirus for the lung and brain was increased compared with baculovirus itself possibly owing to increased stability of baculovirus by pegylation.

Animals↗
PubMed2006

The role of iron in reactive oxygen species generation from diesel exhaust particles.

Diesel exhaust particles (DEP) are known to produce reactive oxygen species (ROS), which induce oxidative stress and inflammation in the lung and respiratory tract. DEP are composed of polycyclic aromatic hydrocarbons (PAH) and their derivatives, redox active semi-quinones, and trace amounts of heavy metals. ROS production was measured by thiobarbituric acid-reactive substances of deoxyribose (TBARS) formation from DEP samples obtained from Korea (DEP-KO), and the Standard Reference Material (SRM) 2975 to explore the role of transition metals. Both DEP-KO and SRM2975 had similar amounts of transition metals, whereas DEP-KO contained more iron, but less copper and zinc, than SRM2975. The water-soluble fraction from SRM2975, but not that from DEP-KO, had a broad absorption in the visible region, but not from DEP-KO, obscuring an accurate absorption measurement of TBARS. Fluorescence measurements of TBARS generation in a water-soluble extract showed that SRM2975 produces more TBARS, but the addition of hydrogen peroxide (H2O2) generated more TBARS in DEP-KO than in SRM2975, consistent with the higher amounts of iron in DEP-KO. The incubation of DEP with iron chelators inhibited the production of TBARS. Finally, a novel use of the fluorogenic spin trap probe, proxyl fluorescamine, enabled the detection of the ROS production from both DEP-KO and SRM2975. Our findings suggested that careful consideration is needed to measure TBARS production in DEP, and that iron in DEP seems to be more important than other transition metals in H2O2-induced ROS generation.

Fluorescence↗
PubMed2004

Modelling Tityus scorpion venom and antivenom pharmacokinetics. Evidence of active immunoglobulin G's F(ab')2 extrusion mechanism from blood to tissues.

Modelling Tityus scorpion venom and antivenom pharmacokinetics. Evidence of active immunoglobulin G's F(ab')(2) extrusion mechanism from blood to tissues. We measured pharmacokinetic parameters for T. discrepans venom in rams. Forty, 75 or 100 microg/kg venom were injected subcutaneously in the inner side of the thigh. Plasma venom content (venenemia) was determined by enzyme-linked immunosorbent assay (ELISA) from 0 to 300 min after injecting venom. Venenemia was fit to a three-compartment model (inoculation site, plasma and extra vascular extracellular space), it was assumed that the venom may also be irreversibly removed from plasma. Calculated time course of venom content shows that at any time no more that 30% of the venom is present in plasma. Venenemia peaks at 1h and decays afterwards. Fluorescently labelled antivenom [horse anti-TityusF(ab')(2) or fraction antigen binding, immuglobulin without Fc chain covalently bound to fluorescine or fluorescamine] pharmacokinetics was determined. Although F(ab')(2) molecular weight is >/=10 times bigger that toxin's, the rate of outflow of F(ab')(2) from blood to tissues was approximately 4 times faster than the venom's outflow. Venom content in the injection site decays exponentially for >6h, this prediction was confirmed immunohistochemically. Only approximately 5% of the venom is eliminated in 10h; approximately 80% of the venom is in the tissues after 2h and remains there for >10h.

Animals↗
PubMed1996

Altered membrane phospholipid organization and erythrophagocytosis in E beta-thalassemia.

The underlying cause behind the accelerated destruction of erythrocytes in the bone marrow and in the peripheral circulation, accompanying the beta-thalassemic syndromes is still not clearly understood. The present investigation demonstrates that increased phagocytosis of erythrocytes in E beta-thalassemia is inhibited by the presence of phosphatidylserine (PS) vesicles, suggesting a PS-'PS-receptor' type of interaction in premature recognition of these erythrocytes by macrophages. Increased exposure of both aminophospholipids phosphatidylethanolamine (PE) and PS was demonstrated by fluorescamine labeling and annexin binding, respectively. The slower rate of translocation of PS across the bilayer suggested that this contributed towards the increased exposure of PS in E beta-thalassemic erythrocytes.

Annexins↗
PubMed1994

Alpha-helical hydrophobic polypeptides form proton-selective channels in lipid bilayers.

Proton translocation is important in membrane-mediated processes such as ATP-dependent proton pumps, ATP synthesis, bacteriorhodopsin, and cytochrome oxidase function. The fundamental mechanism, however, is poorly understood. To test the theoretical possibility that bundles of hydrophobic alpha-helices could provide a low energy pathway for ion translocation through the lipid bilayer, polyamino acids were incorporated into extruded liposomes and planar lipid membranes, and proton translocation was measured. Liposomes with incorporated long-chain poly-L-alanine or poly-L-leucine were found to have proton permeability coefficients 5 to 7 times greater than control liposomes, whereas short-chain polyamino acids had relatively little effect. Potassium permeability was not increased markedly by any of the polyamino acids tested. Analytical thin layer chromatography measurements of lipid content and a fluorescamine assay for amino acids showed that there were approximately 135 polyleucine or 65 polyalanine molecules associated with each liposome. Fourier transform infrared spectroscopy indicated that a major fraction of the long-chain hydrophobic peptides existed in an alpha-helical conformation. Single-channel recording in both 0.1 N HCl and 0.1 M KCl was also used to determine whether proton-conducting channels formed in planar lipid membranes (phosphatidylcholine/phosphatidylethanolamine, 1:1). Poly-L-leucine and poly-L-alanine in HCl caused a 10- to 30-fold increase in frequency of conductive events compared to that seen in KCl or by the other polyamino acids in either solution. This finding correlates well with the liposome observations in which these two polyamino acids caused the largest increase in membrane proton permeability but had little effect on potassium permeability. Poly-L-leucine was considerably more conductive than poly-L-alanine due primarily to larger event amplitudes and, to a lesser extent, a higher event frequency. Poly-L-leucine caused two populations of conductive events, one in the 0.1-0.5 pA range, and one in the 1.0-5.0 pA range, whereas nearly all events caused by poly-L-alanine were in the 0.1-0.5 pA range at an applied voltage of +60 mV. The channel-like activity appeared to switch between conductive and nonconductive states, with most open-times in the range of 50-200 ms. We conclude that hydrophobic polyamino acids produce proton-conducting defects in lipid bilayers that may be used to model functional proton channels in biological membranes.

Alamethicin↗
PubMed2000

Determination of aromatic amines in water samples by capillary electrophoresis with electrochemical and fluorescence detection.

Two capillary electrophoresis methods have been compared for the determination of aniline derivatives in environmental water samples. With the first method the anilines were separated as cations by free zone electrophoresis at low pH, and detected by amperometry. For this, the separation capillary was connected through a palladium field decoupler to an electrochemical detection cell which had been modified to match the volume scale of the separation. Most anilines tested, except chlorinated compounds, could be detected with full sensitivity at a detection potential of +0.7 V. Detection limits with this detection scheme were on a low microg/l level. The alternative method involved the derivatization of the anilines with fluorescamine, the separation of the derivatives formed by micellar electrokinetic chromatography, and fluorescence detection. For detection a lamp-based, fibre optics instrument was used. Detection limits with fluorimetry were comparable with those obtained with amperometric detection (in the order of 1 microg/l). Still, this method was preferred since it gave a higher separation efficiency and shorter analysis times (approximately 4 min). The most important argument, however, was its higher reliability and ease-of-handling. Preliminary experiments with water samples collected in areas where pollution with anilines may be expected showed that the method is highly specific, with few interferences showing up in the electropherograms.

Amines↗
PubMed1981

Simple method for the simultaneous determination of histamine, polyamines and histone H1.

Histamine, putrescine, spermidine, spermine and histone H1 in tissue extracts were separated step by step on a small cellulose phosphate column (3 x 0.6 cm). Borate buffers (pH 8.5) of different ionic strength were used for the separation. Histamine was determined fluorimetrically by reaction with o-phthalaldehyde. Other substances were determined spectrophotometrically by reaction with 2,4,6-trinitrobenzene sulphonate or fluorimetrically by reaction with fluorescamine. Quantitative determinations can be carried out on 0.1 nmol of histamine, about 1 nmol of polyamines and 0.5 microgram of histone H1 by fluorimetry, and 10--20 nmol of polyamines and 50 micrograms of histone H1 by spectrophotometry. The method is simple, does not require costly equipment and allows the analysis of many samples simultaneously.

Brain Chemistry↗
PubMed1977

An in situ fluorimetric method for the detection and quantitative analysis of fenitrothion, its breakdown products and other amine-generating compounds.

A procedure is described for the in situ detection of primary amine-generating pesticides on thin layers of silica gel. The technique is based on the reaction of fluorescamine with primary amines to yield highly fluorescent derivatives. Nitro compounds are first reduced to their corresponding primary amines. Pesticides studied were aminotriazole, fenitrothion, parathion and parathion-methyl. Possible breakdown products of fenitrothion were also included. Detection limits were in the low nanogram range. The method is simple, rapid and very selective and can also distinguish between primary amines and nitro compounds. An example of a typical chromatographic separation is presented and quantitative aspects are discussed.

Amines↗
PubMed1989

Determination of elastase activity by reversed-phase high-performance liquid chromatography.

The action of elastase on elastin was measured by high-performance liquid chromatography with on-line post-column derivatization. After alkaline hydrolysis, a 20-ml sample was injected into a ODS-2 gel column. An elastin-specific dipeptide, Val-Pro, and the internal standard, Gly-Leu, were eluted by a linear gradient of 0 to 10% of 1-propanol in 50 mM heptafluorobutyrate (pH 3) at a flow-rate of 1 ml/min. The eluent was reacted with fluorescamine, and the fluorescent products were measured. Retention times for Val-Pro and Gly-Leu were 17.33 and 23.54 min. The peak areas of 0.2-16 micrograms of Val-Pro gave a straight-line plot. Elastase activity was constant from 6 to 24 h and was 0.95 +/- 0.02 (S.D.) micrograms/h. The method may be useful for the measurement of the elastolytic activity in some diseased tissues.

Chromatography, High Pressure Liquid↗
PubMed1975

High-performance liquid chromatographic analysis of amino acids and peptide-hormone hydrolysates in the picomole range.

A high-pressure liquid chromatographic system for the separation of amino acids and peptide-hormone hydrolysates is described. A modified high-pressure liquid chromatography (Hewlett-Packard, model 1010B) equipped with an automatic gradient-generating system, and the applications of fluorescamine and ion-exchange resins of particle size 8 +/- 2 mum permit the detection of amino acids in the picomole range with good resolution. Compared with conventional amino acid analyzers, the times for separation are reduced by a factor of 3--4.

Amino Acids↗
PubMed1985

Interaction between fluorescence-labeled fibronectin fragments studied by gel high-performance liquid chromatography.

Fibronectin is a large, adhesive glycoprotein which self-associates on many cell surfaces. We have begun to study this reaction by determining the domains of fibronectin which interact with each other. To avoid possible solid-phase artifacts of affinity chromatography, we have devised a solution-phase assay in which the smallest fibronectin fragment is labeled with fluorescamine, mixed with unlabeled fibronectin, and complexation is observed by the appearance of a new higher-molecular-weight peak on gel high-performance liquid chromatography columns. The assay allowed use of excess unlabeled reactant, high-sensitivity, low background without removal of reagent, and fast analysis. Our results show that the amino- and carboxyl-terminal fibronectin fragments bind the native molecule in solution.

Chromatography, High Pressure Liquid↗
PubMed1991

Development of a screening method for five sulfonamides in salmon muscle tissue using thin-layer chromatography.

A thin-layer chromatographic (TLC) method was developed for the analysis of five sulfonamides [sulfadiazine (SDZ), sulfamerazine (SMRZ), sulfamethazine (SMTZ), sulfadimethoxine (SDMX) and sulfapyridine (SP)] in salmon muscle tissue. "Matrix solid-phase dispersion" was employed whereby the tissue sample was ground with C18-derivatized silica gel. This material was packed into a column and washed with 10% toluene in hexane (discarded) followed by dichloromethane which was evaporated. The residue was chromatographed on a high-performance TLC plate using ethyl acetate-n-butanol-methanol-aqueous ammonia (35:45:15:2, v/v). Sulfonamides were detected after spraying the plate with a solution of fluorescamine. Method parameters were determined by analyzing spiked salmon muscle tissue samples. The method detection limits at the 99% confidence level were 0.11, 0.44, 0.07, 0.13 and 0.13 ppm for SDZ, SMRZ, SMTZ, SDMX and SP, respectively. The lowest-detectable levels were approximately 0.04 ppm for SDZ, SMTZ, SDMX and SP, and 0.10 ppm for SMRZ. The average recoveries of analyses were 61, 63, 60, 63 and 57% for SDZ, SMRZ, SMTZ, SDMX and SP, respectively, and were found to be analyst-dependent. The method was found to give linear detector responses for all analytes over spiking levels ranging from 0 to 2 ppm.

Animals↗
PubMed1983

Improved cost effective thin-layer detection techniques for routine surveillance of commonly abused drugs in drug abuse urine screening and proficiency testing programs with built-in quality assurance.

Improved, sensitive, reliable and cost effective thin-layer detection procedures for poly-drug usage (12-15 drug evaluations per specimen) are presented. Extraction procedures using ion-exchange resin loaded paper and liquid-liquid extraction with the built-in quality assurance program are reported. The combined use of ninhydrin-fluorescamine detection reagent for the identification of various central nervous system stimulants is only one of the several modifications and improvements made during the past 14 years. Laboratories, participating in proficiency testing programs in drug abuse toxicology monitoring are encourage the use of proposed extraction and identification techniques.

Chromatography, Paper↗
PubMed1979

Quantitative liquid chromatographic determination of cefatrizine in serum and urine by fluorescence detection after post-column derivatization.

A fast, specific and sensitive high-performance liquid chromatographic procedure for the determination of cefatrizine, an orally active cephalosporin, in serum and urine is proposed. The drug is determined by the internal standard method, using cephradine as the internal standard. The separation is carried out on a reversed-phase column, filled with octadecylsilane chemically bonded microparticles. The eluent is a mixture of acetonitrile with 0.025 M sodium phosphate buffer (pH 7). Quantitation is effected by fluorescence detection of the fluorophores formed after post-column derivatization with fluorescamine in a packed-bed reactor. The chromatographic conditions and the conditions for the post-column derivatization are discussed. The method has been applied to serum and urine samples, which were analysed after deproteinization with trichloroacetic acid and injection of the clear supernatant. The accuracy and reproducibility of the procedure were investigated by the determination of the cefatrizine content in spiked serum and urine samples.

Cefatrizine↗
PubMed2003

Mesenchymal stem cells, MG63 and HEK293 transfection using chitosan-DNA nanoparticles.

Chitosan-DNA nanoparticles were synthesized from the complexation of the cationic polymer with a ss-gal DNA plasmid, in order to study the efficacy of chitosan to develop a non-viral gene delivery system that can be optimized for efficient gene therapy. The optimal binding conditions were determined with the fluorescamine and PicoGreen assays. DNA distribution within the nanoparticle was visualized by electron transmission microscopy, while the size and morphology were assessed by atomic force microscopy. The transfection potential was evaluated for the first time on human mesenchymal stem cells (MSCs), on human osteosarcoma cells (MG63) and on human embryonic kidney cells (HEK293). The LipofectAMINE(TM) 2000 (LF) reagent was used in comparison. The effect of chitosan-DNA nanoparticles on cell viability was illustrated with the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) assay. The nanoparticles formed are of a diameter inferior to 100nm with a homogenous distribution of DNA. The transfection of HEK293 cells is superior to that seen with MG63 cells and MSCs, however not surpassing that seen with LF. Minimal cytotoxicity is seen with the polyplexes compared to greater than 50% toxicity with LF. These results suggest that chitosan-DNA nanoparticles have favorable characteristics for non-viral gene delivery, are cell type dependent and not cytotoxic.

Cell Line↗