title stringlengths 0 1.13k | abstract stringlengths 1 15.7k | PMID int64 22 36.5M |
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Reversal of the enantiomeric elution order of some aromatic amino acids using reversed-phase chromatographic supports coated with the teicoplanin chiral selector. | In this paper, two chiral stationary phases were prepared by coating the surface of both C8 and C18 high-performance liquid chromatography (HPLC) supports with the teicoplanin chiral selector. The hydrophobic C11 acyl side chain, attached to the D-glucosamine group of teicoplanin, served as anchor moiety for the immobilization of the chiral selector on the apolar support material. The retention and enantioselectivity of these coated stationary phases were studied using some aromatic amino acids as probe solutes and an aqueous solution as mobile phase. It was found that the enantiomer elution order on the modified C8 and C18 stationary phases was reversed (L>D) relatively to that classically observed with a teicoplanin covalently immobilized on a silica support (D>L). Such a dynamic coating on the reversed-phase supports was found to be of interest since the apparent enantioselectivity was not significantly changed by the use during an extended period of time or following a long-term storage of the columns. | 18,970,428 |
Capillary electrophoretic system incorporating an UV/CL dual detector. | We developed a capillary electrophoretic system incorporating an ultra-violet absorption (UV)/chemiluminescence (CL) dual detector, taking advantage of the CL reaction of luminol-hydrogen peroxide and the batch-type CL detection cell. UV detection was carried out using the on-capillary method while CL detection was performed using the end-capillary method. Examination of isoluminol isothiocyanate (ILITC) as a model sample revealed two main peaks with UV detection and one main peak with CL detection. The first peak in the UV detection data corresponded to the main peak in the CL detection data. We then determined that the ILITC sample included natural ILITC as well as an impurity that had absorption behavior but did not have CL properties and labeling ability. Furthermore, the components of a mixture containing glycine, glycylglycine and glycylglycylglycine, all labeled with ILITC, were well separated and detected using the present system. The present system easily, rapidly, and simultaneously produces useful information due to the presence of both UV and CL detectors. | 18,970,433 |
Evaluation of different sample extraction strategies for selenium determination in selenium-enriched plants (Alliumsativum and Brassicajuncea) and Se speciation by HPLC-ICP-MS. | Several sample extraction techniques have been evaluated in order to obtain highest selenium (Se) extraction efficiency in two types of selenium-enriched plants (Allium sativum and Brassica juncea). Three extracting solutions have been studied for this purpose: 0.1M HCl, 25mM ammonium acetate buffer (pH 5.6) and protease in aqueous solution. In each case, the effect of the ultrasonic probe during extraction was also evaluated. Selenium extraction yields were calculated based on the ICP-MS determination of the total selenium content in the corresponding extracts and in the plant tissue after its microwave digestion. The action of ultrasounds allowed the reduction on the extraction time while maintaining good Se recoveries (which ranged from 75 to 120% of the total Se in the plant). The accuracy of total Se determination was controlled by analyzing a reference material (aquatic plant, BCR-670). On the other hand, speciation studies of the extracts were carried out by using ion-pairing reversed phase and size exclusion/ion exchange (Shodex Asshipak) liquid chromatographic columns. The two separation mechanisms were suitable to isolate the main extractable Se species which were identified as Se-methyl selenocysteine and Se-methionine in both systems. The extracts of both plants (A. Sativum and B. juncea) exhibited also the presence of several unknown Se-species. | 18,970,462 |
Use of FTIR spectroscopy coupled with ATR for the determination of atmospheric compounds. | Attenuated total reflection Fourier transformed infrared spectroscopy (ATR-FTIR) can be successfully used for the quantitative determination of small amounts of pollutants like the organic fraction of aerosols. The relation between sample concentration and reflectance is described by the Kubelka-Munk equation and was found to be linearly proportional to the absorption band of some functional group. Several parameters like the matter of solid matrix, the cleaning of the sampling support, the treatment of reflectance spectra and the base line correction considerably influenced the reflectance spectra and facilitated data interpretations. The feasibility of the ATR-FTIR was evaluated by the monitoring of specific organic group bands on filters collected in the French cities of Grenoble and Clermont-Ferrand. We have obtained for hydroxyl group a calibration curve by plotting the relative intensity of reflectance versus the concentration. The linearity was obtained for OH from 1x10(-1) to 1x10(0)molL(-1) with r(2)=0.9959. We can consider that for a direct measurement of the intensity of reflectance, it is possible to perform quantitative ATR-FTIR organic group analysis. | 18,970,463 |
Plastified poly(ethylene terephthalate) (PET)-toner microfluidic chip by direct-printing integrated with electrochemical detection for pharmaceutical analysis. | Rapid separation and determination of acetaminophen and its hydrolysate with end-channel electrochemical (EC) detection integrated on a plastified poly(ethylene terephthalate) (PET)-toner microchip capillary electrophoresis (CE) system was investigated. In this separation and detection system, a Pt ultramicroelectrode integrated on a three-dimensional adjustor was used as working electrode. Factors influencing the separation and detection were investigated and optimized. Results show that acetaminophen and p-aminophenol can be well separated within 84s with R.S.D.<1% for migration time and R.S.D.<3.6% for detection current for both analytes. Detection limits for both analytes are determined to be 5.0muM (S/N=3). This method has been successfully applied to the detection of trace p-aminophenol in paracetamol tablets. The results demonstrate that the PET-toner microchips can obtain better performance than PDMS microfluidic devices but at much lower cost. | 18,970,464 |
Determination of mono- and dichloroacetic acids in betaine media by liquid chromatography. | A simple and sensitive method has been developed for the analysis of residue amounts of chloroacetic acids in betaine samples based on derivatization by 1-naphthylamine (NA). The derivatized compounds are analyzed by reverse phase high performance liquid chromatography using methanol and water as mobile phase in the ratio of 32/68 (v/v) and phenyl column and PDA detection at 222nm. The detection limits (LOD) of monochloroacetic acid (MCA) and dichloroacetic acid (DCA) are 0.1 and 0.15mugmL(-1), respectively. The limits of quantification (LOQ) and the linear dynamic ranges (LDR) of MCA are found to be 1 and 1-400mugmL(-1), respectively, and for DCA are found to be 3 and 3-400mugmL(-1), respectively. The precision at the 5ppm level for MCA and DCA are about 3% and 2%, (n=5), respectively. The average recovery for MCA and DCA spiked to betaine samples are 98% and 97%, respectively. | 18,970,478 |
Micro-columns packed with Chlorella vulgaris immobilised on silica gel for mercury speciation. | A method has been developed for mercury speciation in water by using columns packed with Chlorella vulgaris immobilised on silica gel. The method involves the retention of CH(3)Hg(+) and Hg(2+) in micro-columns prepared by packing immobilised algae in polypropylene tubes, followed by selective and sequential elution with 0.03 and 1.5M HCl for CH(3)Hg(+) and Hg(2+), respectively. The adsorption capacity of the micro-algae for Hg(2+) and CH(3)Hg(+) has been evaluated using free and immobilised C. vulgaris. The efficiency uptake for both species at pH 3 was higher than 97%. Studies were carried out on the effect of retention and elution conditions for both species. Furthermore, the stability of mercury species retained on algae-silica gel micro-columns and lifetime of the columns were also investigated. Hg(2+) showed a higher stability than CH(3)Hg(+) at 0 degrees C (21 and 3 days, respectively) and a better lifetime than for the organic species. The developed method was applied to the analysis of spiked tap, sea and wastewater samples. Recovery studies on tap and filtered seawater provided results between 96+/-3 and 106+/-2 for Hg(2+) and from 98+/-5 to 107+/-5 for CH(3)Hg(+), for samples spiked with single species. For samples spiked with both CH(3)Hg(+) and Hg(2+), the average recoveries varied from 96+/-5 to 99+/-3 and from 103+/-6 to 115+/-5 for Hg(2+) and CH(3)Hg(+), respectively. However, the percentages of retention and elution on wastewater and unfiltered seawater were only adequate for the inorganic species. | 18,970,490 |
Metabolic profiling using principal component analysis, discriminant partial least squares, and genetic algorithms. | The aim of this study was to evaluate evolutionary variable selection methods in improving the classification of (1)H nuclear magnetic resonance (NMR) metabonomic profiles, and to identify the metabolites that are responsible for the classification. Human plasma, urine, and saliva from a group of 150 healthy male and female subjects were subjected to (1)H NMR-based metabonomic analysis. The (1)H NMR spectra were analyzed using two pattern recognition methods, principal component analysis (PCA) and partial least square discriminant analysis (PLS-DA), to identify metabolites responsible for gender differences. The use of genetic algorithms (GA) for variable selection methods was found to enhance the classification performance of the PLS-DA models. The loading plots obtained by PCA and PLS-DA were compared and various metabolites were identified that are responsible for the observed separations. These results demonstrated that our approach is capable of identifying the metabolites that are important for the discrimination of classes of individuals of similar physiological conditions. | 18,970,515 |
Trends in metal-binding and metalloprotein analysis. | This review describes recent tendencies for metal-binding and metalloprotein analysis, emphasizing metal quantification in proteins through X-ray, atomic absorption, mass spectrometric techniques, and others. Hyphenated techniques such as capillary electrophoresis-synchrotron radiation X-ray fluorescence (CE-SRXRF), laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), matrix-assisted laser desorption/ionisation-time-of-flight mass spectrometry (MALDI-TOF-MS), etc. are also presented. As protein separation techniques electrophoresis (mainly sodium dodecyl sulphate-polyacrylamide gel electrophoresis, SDS-PAGE), capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC) are indicated, due to their inherent sensitivity, resolution and/or easy implementation. Latest challenges in metallomics are also commented. | 18,970,524 |
Highly sensitive and selective spectrofluorimetric determination of tolnaftate through the formation of ternary inclusion complex of beta-naphthol/beta-cyclodextrin/anionic surfactant system. | An indirect spectrofluorimetric method with high sensitivity and selectivity was developed for the determination of antifungal drug: tolnaftate (TNF), depending on the supramolecular multi-recognition interaction among the anionic surfactant sodium laurylsulfate (SLS), beta-cyclodextrin (beta-CD) and beta-naphthol (ROH). The mechanism of the inclusion was studied and discussed by means of fluorescence spectrum, infra-red spectrograms and (1)HNMR spectroscopy. Results showed that the naphthalene ring of ROH and the hydrophobic hydrocarbon chain of SLS were included into the beta-CD's cavity to form a ROH:SLS:beta-CD ternary inclusion complex with stoichiometry of 1:1:1 at room temperature, which provided effective protection for the excited state of ROH. At lambda(ex)/lambda(em)=273/360 nm, the fluorescence intensity was linear over a tolnaftate concentration range of 2.46 x 10(-9) to 2.10 x 10(-6)mol L(-1). The detection limit and relative standard deviation was 7.50 x 10(-10)mol L(-1) and 1.4%, respectively. The interference of 31 foreign substances was slight. The proposed method had been successfully applied to the determination of tolnaftate in artificial mixed samples with almost quantitative recovery. | 18,970,541 |
Trace analysis of acids and bases by conductometric titration with multiparametric non-linear regression. | A chemometric method for analysis of conductometric titration data was introduced to extend its applicability to lower concentrations and more complex acid-base systems. Auxiliary pH measurements were made during the titration to assist the calculation of the distribution of protonable species on base of known or guessed equilibrium constants. Conductivity values of each ionized or ionizable species possibly present in the sample were introduced in a general equation where the only unknown parameters were the total concentrations of (conjugated) bases and of strong electrolytes not involved in acid-base equilibria. All these concentrations were adjusted by a multiparametric nonlinear regression (NLR) method, based on the Levenberg-Marquardt algorithm. This first conductometric titration method with NLR analysis (CT-NLR) was successfully applied to simulated conductometric titration data and to synthetic samples with multiple components at concentrations as low as those found in rainwater (approximately 10 micromol L(-1)). It was possible to resolve and quantify mixtures containing a strong acid, formic acid, acetic acid, ammonium ion, bicarbonate and inert electrolyte with accuracy of 5% or better. | 18,970,555 |
Flow-injection turbidimetric determination of homatropine methylbromide in pharmaceutical formulations using silicotungstic acid as precipitant reagent. | A flow-injection turbidimetric procedure exploiting merging zones is proposed for determining homatropine methylbromide (HMB) in pharmaceutical preparations. The determination is based on the precipitation reaction of homatropine methylbromide with silicotungstic acid in acidic medium to form a precipitate, which was measured at 410 nm. The analytical curve was linear in the HMB concentration range from 8.1 x 10(-5) to 2.2 x 10(-4)mol l(-1), with a detection limit of 5.0 x 10(-6)mol l(-1). The recoveries ranged from 96 to 103%, the sampling frequency was 70 determinations per hour and relative standard deviations were less than 1.5% (n=10). The results obtained for commercial formulations using the FIA procedure were in good agreement with those obtained by using a comparative method. | 18,970,560 |
Amperometric determination of chloroguaiacol at submicromolar levels after on-line preconcentration with molecularly imprinted polymers. | In this study, a sorbent flow preconcentration system coupled to amperometric detector for the chloroguaiacol (4-chloro-2-methoxyphenol) determination at submicromolar levels is described. The satisfactory selectivity of the proposed method was attained by means of the use of a chloroguaiacol-imprinted polymer, whose the synthesis was carried out by bulk polymerization. Flow and chemical parameters associated to the preconcentration system, such as sample pH, preconcentration and elution flow rates, concentration of the carrier solution (KCl) and eluent volume were investigated through multivariate analysis. The flow preconcentration of chloroguaiacol was not affect by equimolar presence of structurally similar phenolic compounds including catechol, 4-chloro-3-methylphenol, 4-aminophenol and 2-cresol, thus showing the good performance of the imprinted polymer. Under the best experimental conditions, it was obtained a preconcentration factor of 110-fold and low detection and quantification limits of 27 and 78 nmol L(-1), respectively. The analytical curve covered a wide linear range from 0.05 up to 5.0 micromol L(-1) (r>0.999) and satisfactory precision (n=8) evaluated by relative standard deviation (R.S.D.) were respectively, 5.5 and 4.2%, for solutions of 1.0 and 5.0 micromol L(-1) chloroguaiacol. Other parameters related to the performance of the flow system were also evaluated including concentration efficiency of 27.5 min(-1) and consumptive index of 0.09 mL. Recoveries varying from 93 up to 112% for water samples (tap water and river water) spiked with chloroguaiacol concentration were achieved, thus assuring the accuracy of the proposed flow preconcentration system. | 18,970,563 |
Periodically interrupted amperometry at membrane coated electrodes: a simplified pulsed amperometry. | Amperometric detection combined with separation technique or with selective molecular recognition step can be very effective solving quantitative analytical tasks. When the amperometric working electrode surface needs cleaning or reactivation, pulsed amperometric technique can be the choice. Coating working electrodes with different sensitizing or protecting layer is quite common in the practice of voltammetric analysis. In these studies the behavior of coated electrodes using a simplified pulsed amperometric working program which can be named periodically interrupted amperometric (PIA) detection has been investigated. Rotating platinum, and carbon paste electrodes coated with dialysis film or porcine intestinal membrane were used in the experiments. The signal in case of electrochemical oxidation of hydrogen peroxide and ascorbic acid at convective conditions has been evaluated. The signal, obtained with conventional amperometry has been compared with signal collected with a periodically interrupted amperometric measuring program, allowing time for the diffusion to reload the diffusion layer at the electrode surface. The sensitivity and the lower limit of detection (4.5 x 10(-7)M for ascorbic acid and 2 x 10(-6)M for H2O2) proved superior in case of the periodically interrupted amperometry. | 18,970,566 |
Separation and preconcentration of U(VI) on XAD-4 modified with 8-hydroxy quinoline. | Amberlite XAD-4 adsorber resin was modified with 8-hydroxy quinoline (Oxine) by equilibrating with methanol solution of the reagent and the modified resin was used as a support material for the solid phase extraction and preconcentration of UO(2)(2+) from aqueous solution at pH between 4 and 5.5. Ten micrograms of uranium from 300 ml of aqueous phase could be quantitatively extracted in to 1g of the modified resin giving an enrichment of 200. Uranium collected in the column could be eluted out with methanol-HCl mixture and determined spectrophotometrically using arsenazo(III) as the chromogenic reagent. The preconcentration could be made selective to uranium by using EDTA as a masking agent for transition metal ions and Th(IV). | 18,970,579 |
A validation protocol for the HPTLC standardization of herbal products: application to the determination of acteoside in leaves of Plantago palmata Hook. f.s. | Formal validation, that is the study of the analytical performances of a method, is recognized as the best safeguard against the generation and publication of data with low reliability. Although the topic of HPTLC validations has been largely investigated, there is still a need for a general validation method applicable whenever a blank matrix cannot be reconstituted, notably herbs and their extracts. This work proposes two validation schemes aiming at generate linearity, accuracy and precision data in a minimal number of HPTLC plates, taking the standardization of Plantago palmata as an example with both UV and visible (post-chromatographic derivatization with a sulphuric acid-vanillin reagent) detections. A major problem associated with HPTLC determinations is underlined, namely the low range of linearity which makes spiking studies quite difficult as care must be taken to avoid overloading, whereas keeping the analyte detectable in blank extracts and avoiding spikes too close to endogenous levels. A second problem is the use of general post-chromatographic derivatization reagents that compromise the selectivity of the method by reacting with compounds that may not be resolved from the compound of interest. The use of such reagents is clearly not without danger, especially given the relatively low resolution of planar chromatography. In conclusion, the retained validation protocol effectively yields the main validation data whereas allowing to pinpoint major analytical drawbacks. It was not possible to simultaneously validate aucubin and acteoside assays as both analytes are present at too different levels/detectabilities. | 18,970,583 |
Conductometric nitrate biosensor based on methyl viologen/Nafion/nitrate reductase interdigitated electrodes. | A highly sensitive, fast and stable conductometric enzyme biosensor for determination of nitrate in water is reported for the first time. The biosensor electrodes were modified by methyl viologen mediator mixed with nitrate reductase (NR) from Aspergillus niger by cross-linking with glutaraldehyde in the presence of bovine serum albumin and Nafion((R)) cation-exchange polymer. The process parameters for the fabrication of the enzyme electrode and various experimental variables such as pH, the enzyme loading and time of immobilization in glutaralaldehyde vapor were investigated with regard to their influence on sensitivity, limit of detection, dynamic range and operational and storage stability. The biosensor can reach 95% of steady-state conductance value in about 15s. Linear calibration in the range of 0.02 and 0.25 mM with detection limits of 0.005 mM nitrate was obtained with a signal-to-noise ratio of 3. When stored in 5 mM phosphate buffer (pH 7.5) at 4 degrees C, the sensor showed good stability over 2 weeks. | 18,970,588 |
Determination of 6-mercaptopurine based on the fluorescence enhancement of Au nanoparticles. | A novel method for the determination of 6-mercaptopurine (6MP) has been developed based on fluorescence enhancement of Au nanoparticles (AuNPs). The fluorescent AuNPs with mean diameter of approximately 15 nm were synthesized in aqueous solution, exhibiting the stable maximum emission at 367 nm, under the excitation at wavelength of 264 nm. The AuNPs self-assembly with 6MP were characterized with transmission electron microscopy (TEM), ultraviolet-visible (UV-vis) absorption, fluorescence and surface-enhanced Raman scattering (SERS) spectroscopy. The results revealed that the surface attachment through versatile binding sites of S10, N3, N9 and N7 atoms in 6MP produced the interparticle coupling and formed aggregates of AuNPs. As a result, the fluorescence emission enhancement was significantly observed upon AuNPs self-assembly with 6MP. The fluorimetric determination under optimal conditions indicated that 6MP could be quantified in good linearity range of 6.35 x 10(-8) to 3.05 x 10(-7)M, with a low detection limit of 4.82 x 10(-10)M. The relative standard deviation (n=11) was 1.8% at 2.54 x 10(-8)M 6MP concentration level. The proposed method was successfully applied for the determination of 6MP in spiked human urine. The probable fluorescence enhancement mechanism was also discussed there. | 18,970,589 |
Fluorous ionic liquids as solvents for the liquid-liquid extraction of metal ions by macrocyclic polyethers. | The predominant mode of strontium ion transfer from aqueous nitrate media into a series of 1-fluoroalkyl-3-methylimidazolium bis[(trifluoromethylsulfonyl)]imides containing dicyclohexano-18-crown-6 (DCH18C6) is shown to shift from cation exchange to strontium nitrato-crown ether complex partitioning as the length of the fluoroalkyl substituent is increased. Fluoroalkyl substituents are shown to be only slightly more effective than their non-fluorous analogs at inducing this shift. At the same time, the fluorinated ionic liquids (ILs) yield strontium distribution ratios as much as an order of magnitude lower than the corresponding 1-alkyl-3-methylimidazolium (C(n)mim(+)) salts. Fluorous ILs thus appear to offer no compelling advantages over C(n)mim(+) ionic liquids as extraction solvents. | 18,970,599 |
Development of a radiochemical separation for selenium with the aim of measuring its isotope 79 in low and intermediate nuclear wastes by ICP-MS. | Selenium (Se) 79 is a beta emitter produced from (235)U fission thus occurring as one of the fission products found in nuclear reactors. Due to its long half life (about 10(5) years), (79)Se is one of the radionuclides of interest for the performance of assessment studies of waste storage or disposal. Thus, the National Radioactive Waste Management Agency (Andra, France) requests its monitoring in wastes packages before their disposal in specific sites. Measurement of (79)Se is difficult owing to its trace level concentration and its low activity in nuclear wastes. A radiochemical procedure has to be carried out in order to separate selenium from the matrix and to concentrate it before the measurement with a mass spectrometric or a nuclear technique. The beginning of the development is presented in this paper. The optimised protocol firstly developed in view of an ICP-MS measurement, includes five steps based on microwave digestion, evaporation and separations on ion exchange resins. It was tested first on synthetic solutions and was optimised in order to be applicable to a large number of sample types. The recoveries of the whole procedure were evaluated using natural (82)Se or the gamma emitter (75)Se as a radioactive spiker. Then, the protocol was applied to two solid samples spiked with natural selenium, a glass microfiber filter and an ion exchange resin, and two liquid samples spiked with (75)Se, a synthetic solution and an effluent. The yields obtained for both samples ranged from 70 up to 80%. | 18,970,605 |
Determination of metals, metalloids and non-volatile ions in airborne particulate matter by a new two-step sequential leaching procedure Part B: Validation on equivalent real samples. | Due to the lack of proper standard materials for airborne particulate matter collected on filters, a validation scheme was developed, which is here described, to the aim of testing the application of leaching procedures performing both ions and elemental determinations on real samples of airborne particulate matter collected on filters. The scheme has been developed on a two-step leaching method (extraction in acetate buffer and acid dissolution of residue) previously developed by authors and consists of two series of tests to be run on n pairs of equivalent parallel samples filter-collected. The first series of tests aims to assess on real samples the equivalence between results obtained by the tested procedure with those obtained by the EMEP ions extraction and the EN 12341 standard methods, whereas the second aims to evaluate the reproducibility of analytical results of elemental determination in the leached and dissolved fractions; in the latter case data reliability is also evaluated as a function of the environment-intrinsic variability of real samples. To avoid errors due to sampling differences data from filter pairs were standardized both by gravimetric determination of loaded filters, according to the EN 12341 standard and by the rate [SO(4)(2-)](A)/[SO(4)(2-)](B,) where [SO(4)(2-)] indicate the soluble sulphate concentration in the extract; in the latter case values improved for all elements and in both fractions. Results of equivalence with standard methods and reproducibility tests are evaluated as mean relative percentage differences (Delta%) and percentage elements recoveries (R%). The application of the validation scheme to the two-step leaching method is here discussed for non-volatile ions and for 17 elements detected on 22 pairs of low-volume collected PM(10) samples on Teflon filters. | 18,970,608 |
Determination of intrinsic viscosity of poly(ethylene terephthalate) using infrared spectroscopy and multivariate calibration method. | A methodology was developed to determine the intrinsic viscosity of poly(ethylene terephthalate) (PET) using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and multivariate calibration (MVC) methods. Multivariate partial least squares calibration was applied to the spectra using mean centering and cross validation. The results were correlated to the intrinsic viscosities determined by the standard chemical method (ASTM D 4603-01) and a very good correlation for values in the range from 0.346 to 0.780dLg(-1) (relative viscosity values ca. 1.185-1.449) was observed. The spectrophotometer detector sensitivity and the humidity of the samples did not influence the results. The methodology developed is interesting because it does not produce hazardous wastes, avoids the use of time-consuming chemical methods and can rapidly predict the intrinsic viscosity of PET samples over a large range of values, which includes those of recycled materials. | 18,970,616 |
Near-infrared spectroscopy (NIRS) with a fibre-optic probe for the prediction of the amino acid composition in animal feeds. | The amino acids alanine, aspartic acid, glutamic acid, glycine, phenylalanine, valine, lysine, proline, and tyrosine present in feeds with different textures (blocks, tablets, granules and flour (meal) and used in different stages of animal feeding regimes (lactation, growth, maintenance, etc.) were analysed using near-infrared reflectance spectroscopy (NIRS) technology together with a remote reflectance fibre-optic probe. The method allows immediate control of the animal feeds without prior sample treatment or destruction through direct application of the fibre-optic probe on the sample. The regression method used was Modified Partial Least Squares (MPLS). The equations developed to determine the amino acid contents of the feeds afforded high values for the RSQ coefficient (0.814-0.963) in all the amino acids with the exception of lysine (0.687). The statistical prediction descriptors SEP, SEP(C) (with values between 0.134 for valine and 0.015 for aspartic acid) and bias indicated that the amino acid values in feeds predicted with NIRS with a fibre optic probe are comparable to those obtained with the chemical ion-exchange HPLC method. | 18,970,626 |
Determination of PAHs in airborne particles by accelerated solvent extraction and large-volume injection-gas chromatography-mass spectrometry. | A sensitive and automated method is presented for the determination of polycyclic aromatic hydrocarbons (PAHs) in airborne particulate matter. The procedure includes extraction of PM10-bound PAHs by accelerated solvent extraction (ASE) followed by gel permeation chromatography (GPC) clean-up, and large-volume programmable temperature vaporizer (PTV-LV) injection coupled to GC-MS. The limit of detection (LOD) of the whole method, based on a signal-to-noise ratio (S/N) of 3:1, ranged from 0.26pgm(-3) to 3pgm(-3) when air volumes of 760m(3) are collected. The hexane-acetone mixture (1:1, v/v) gave the best recoveries when ASE parameters were fixed at 125 degrees C, 1500psi, and a total time of 10min. The recoveries for all PAHs tested ranged from 96% to 103%, rates similar to those obtained by the Soxhlet reference method. To improve the sensitivity, 70muL were injected. The PTV-LV injection settings were optimized using a statistical design of experiments, including a screening 2(4) full factorial design and a further central composite design. A sensitivity increase from 10 to 50 times was achieved as compared with the conventional 2muL splitless injection. The method was validated with the standard reference material SRM 1649a and applied to real PM10 samples from the monitoring network of the Regional Valencia Government (Spain). The analytical performance of the method shows that it is appropriate to monitor PAHs levels in ambient air according to European Union Directives. In addition, the method can be used when a high sensitivity is required. | 18,970,641 |
Optimization of a single-drop microextraction procedure for the determination of organophosphorus pesticides in water and fruit juice with gas chromatography-flame photometric detection. | A single-drop microextraction (SDME) procedure was developed for the analysis of organophosphorus pesticides (OPPs) in water and fruit juice by gas chromatography (GC) with flame photometric detection (GC-FPD). The significant parameters affecting the SDME performance such as selection of microextraction solvent, solvent volume, extraction time, stirring rate, sample pH and temperature, and ionic strength were studied and optimized. Two types of SDME mode, static and cycle-flow SDME, were evaluated. The static SDME procedure provided more sensitive analysis of the target analytes. Therefore, static SDME with tributyl phosphate (TBP) as internal standard was selected for the real sample analysis. The limits of detection (LODs) in water for the six studied compounds were between 0.21 and 0.56ng/mL with the relative standard deviations ranging from 1.7 to 10.0%. Linear response data was obtained in the concentration range of 0.5-50ng/mL (except for dichlorvos 1.0-50ng/mL) with correlation coefficients from 0.9995 to 0.9999. Environmental water sample collected from East Lake and fruit juice samples were successfully analyzed using the proposed method, but none of the analytes in both lake water and fruit juice were detected. The recoveries for the spiked water and juice samples were from 77.7 to 113.6%. Compared with the conventional methods, the proposed method enabled a rapid and simple determination of organophosphorus pesticides in water and fruit juice with minimal solvent consumption and a higher concentration capability. | 18,970,647 |
Flow injection spectrophotometric determination of andrographolide from Andrographis paniculata. | A simple flow injection colourimetric procedure for determining andrographolide was proposed. It is based on the reaction between andrographolide with 3,5-dinitrobenzoic acid, resulting in an intense purplish red complex with a suitable absorption at 536nm. A standard or sample solution was injected into the 3,5-dinitrobenzoic acid stream (flow rate of 1.0mlmin(-1)) which was then merged with potassium hydroxide stream with the same flow rate. Optimum conditions for determining andrographolide were investigated by univariate method. Under the optimum conditions, a linear calibration graph was obtained over the range 5.0-150.0mugml(-1) and the detection limit was 1.50mugml(-1) (3sigma). The relatives standard deviation of the proposed method calculated from 10 replicate injections of 10.0 and 80.0mugml(-1) andrographolide were 0.66% and 1.64%, respectively. The sample throughput was 50h(-1). The proposed method has been satisfactorily applied to the determination of andrographolide in herb plant samples. | 18,970,655 |
Quantitative analysis of isoflavone aglycones in human serum by solid phase extraction and liquid chromatography-tandem mass spectrometry. | This paper describes a liquid chromatography-electrospray-tandem mass spectrometry (LC-ESI-MS/MS) for the qualitative and quantitative analysis of three isoflavone aglycones (glycitein, daidzein and genistein) in human serum. Positive ion mode was used for the detection of these compounds and selective reaction monitoring (SRM) was employed for quantitative measurement. The SRM transitions monitored were as 285.0-->242.0, 270.0 for glycitein, 255.0-->137.0, 153.0, 181.0, 199.0 for daidzein and 271.0-->153.0, 215.0 for genistein. d(3)-Daidzein was used as an internal standard for quantitative measurement. The linearity was good from 0.5 to 500ng/ml. The detection limit based on a signal-to-noise ratio of three was 0.27, 0.38 and 0.29ng/ml for glycitein, daidzein and genistein, respectively. A newly developed solid phase extraction (SPE) procedure was developed for sample pre-treatment. Good recovery, 92.3-103.2%, for three isoflavone aglycones were obtained. This newly developed method was successfully applied to evaluate isoflavone pharmacokinetic in human serum after oral administration. | 18,970,663 |
Determination of diethylhexyl phtalate in water by solid phase microextraction coupled to high performance liquid chromatography. | Difficulties detected in the determination of the diethylhexylphthalate (DEHP) at trace levels by gas chromatography-mass spectrometry (GC-MS) using SPME, due to its ubiquitous distribution in the environment has been overcome and a new method for the determination of DEHP in drinking water has been proposed. The method is based on solid phase microextraction (SPME) coupled to high-performance liquid chromatography (HPLC). Detection was carried out spectrophotometrically. Calibration graph was linear in the range 10-110 microg/L with a regression coefficient of r(2)=0.998 and a detection limit of 0.6 microg/L. The relative standard deviation was 5 and 2% (n=4) for chromatographic areas and retention times, respectively. The usefulness of the SPME-HPLC technique was confirmed. | 18,970,687 |
Comparison of chemical modifiers for selenium determination in soil aqua regia extracts by ZETAAS. | The effect of various chemical modifiers 0.5 g l(-1) Pd, 1% (w/v) Ni, 0.5 g l(-1) Pd+1% (w/v) Ni and 1.0 g l(-1) Pd on the measurement of selenium in soil aqua regia extracts, by ZETAAS, is described. Two Certified Reference Materials (CRMs) RTC-CRM 023-050 and RTC-CRM 025-050 were used for this study. Pyrolysis and atomization curves were obtained for each chemical modifier and their optimal values were assessed. By using standard addition as calibration method, accurate results were obtained for all the chemical modifiers studied. The precision was similar for both CRMs, with a maximum value of 7.5% R.S.D. The limits of detection and quantification for selenium in the soil extracts (n=10) were 3.0 and 6.0 microg l(-1), respectively. The characteristic mass of selenium is assessed as 10 pg. The use of aqua regia as extractant gave quantitative results for selenium in the CRMs assayed. | 18,970,691 |
Determination of soluble phosphates in water samples using ytterbium(III) and dynamic measurements of light scattering intensity at long wavelength. | A selective and fast method has been developed for the determination of phosphates by measuring the formation of ytterbium(III) phosphate through the variation of the light scattering intensity with time. The low solubility of this compound causes an efficient dispersion of the radiation at 490 nm, which is measured at 980 nm using the second-order grating effect. This approach minimizes potential background signals from the sample matrix. The initial rate of the system is automatically obtained in only 0.5s by stopped-flow mixing technique. The variable optimization study has been carried out using univariate and multivariate methods. The dynamic range of the calibration graph is 0.09-7.9 mmol L(-1) (Pearson's correlation coefficient=0.9999) and the detection limit is 0.03 mmol L(-1). The precision of the method, expressed as relative standard deviation, is 2.3%. The study of the potential interference of different inorganic anions showed that arsenate is the main interferent, although it is tolerated in a molar ratio of 5.5. The method has been satisfactorily applied to the determination of soluble phosphates in tap, ground and river water using a previous preconcentration step with a Dowex 1 (1 x 4-400) anionic resin. A 500-fold concentration has been achieved, which has allowed to decrease the detection limit up to 60 mmol L(-1). The recovery range is 97.5-102.5%. The results obtained are consistent with those obtained with the standard molybdenum blue method. | 18,970,693 |
New preservation method for inorganic arsenic speciation in acid mine drainage samples. | A new preservation method has been proposed for the speciation of As(III) and As(V) in acid mine drainage (AMD) samples, characterised by low pH and high metallic content. Samples were taken from a polymetallic sulphides mining area in the province of Huelva (SW Spain), under exploitation until the 1960s for its Cu, Pb and Zn sulphides. The abandoned mine works and the numerous waste rocks heaps produce AMD with high As content, an aqueous pollution source for the nearby streams. Short-term (from few hours to 1 week) preservation of the two inorganic arsenic species was studied, trying different containers (polyethylene, glass), presence or absence of light, temperatures (ambient, refrigerated, frozen), preserving agents and procedures (EDTA, HCl or AcH acids, cation-exchange resin). The speciation results obtained by liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) indicated a rapid conversion of the samples with most of the preservation procedures reported in the literature after 3h after sample collection. A promising method for arsenic preservation has been developed in this work, which maintains the arsenic species distribution in the original samples for a longer time. It consists in the use of opaque glass containers, acidification of the samples with HCl and in situ cleanup with cationic exchange resin, which allowed to preserve the samples for As speciation for at least 48 h. | 18,970,701 |
Inductively coupled plasma-sector field mass spectrometry with a high-efficiency sample introduction system for the determination of Pu isotopes in settling particles at femtogram levels. | An analytical method for the determination of plutonium concentration and its isotope ratio ((240)Pu/(239)Pu) for settling particle samples by inductively coupled plasma mass spectrometry (ICP-MS) is presented. The generally used approach for Pu preconcentration by increasing the amount of samples is not applicable because of the small size of settling particle samples available for the analysis for Pu isotopes. Efforts were made to improve the sensitivity of a sector-field ICP-MS (SF-ICP-MS) and reduce the (238)UH(+) interference for Pu analysis by combining a high-efficiency sample introduction system (APEX-Q). An extremely low detection limit of 0.07 fg Pu was achieved, which allowed the determination of Pu isotope ratio at femtogram levels. The precision and accuracy of (240)Pu/(239)Pu isotope ratio analysis were carefully examined with a certified Pu isotope standard (NBS-947) and an ocean sediment reference material (IAEA-368). Simple anion-exchange chromatography for the separation and purification of Pu was combined with the APEX-Q/SF-ICP-MS system to determine Pu isotopes in settling particles collected in the East China Sea continental margin. The obtained results supported a previous observation on the lateral transport of Pu containing particles in this continental margin. | 18,970,710 |
Determination of methyl ester contents in biodiesel blends by FTIR-ATR and FTNIR spectroscopies. | Partial last square regression (PLS) and artificial neural network (ANN) combined to FTIR-ATR and FTNIR spectroscopies have been used to design calibration models for the determination of methyl ester content (%, w/w) in biodiesel blends (methyl ester+diesel). Methyl esters were obtained by the methanolysis of soybean, babassu, dende, and soybean fried oils. Two sets of samples have been used: Group I, binary mixtures (diesel+one kind of methyl ester), corresponding to 96 biodiesel blends (0-100%, w/w), and Group II, quaternary mixtures (diesel+three types of methyl esters), corresponding to 60 biodiesel blends (0-100%, w/w). The PLS results have shown that the FTNIR model for Group I is more precise and accurate (+/-0.02 and +/-0.06%, w/w). In the case of Group II the PLS models (FTIR-ATR and FTNIR) have shown the same accuracies, while the ANN/FTNIR models has presented better performance than the ANN/FTIR-ATR models. The best accuracy was achieved by the ANN/FTNIR model for diesel determination (0.14%, w/w) while the worthiest was that of dende ANN/FTIR-ATR model (0.6%, w/w). Precisions in Group II analysis ranged from 0.06 to 0.53% (w/w) and coefficients of variation were better than 3% indicating that these models are suitable for the determination of diesel-biodiesel blends composed of methyl esters derived from different vegetable oils. | 18,970,715 |
Electrochemiluminescent behaviors of alkaloids and tris(2,2'-bipyridine) ruthenium in organically modified silicate film. | Electrogenerated chemiluminescences (ECLs) of alkaloids, such as berberine, trigonelline, allantoin and betaine, were studied in an aqueous alkaline buffer solution (pH 9.5), based on tris(2,2'-bipyridine)ruthenium(II) [Ru(bpy)(3)(2+)] immobilized in organically modified silicates (ORMOSILs) film on a glassy carbon electrode (GCE). The immobilized Ru(bpy)(3)(2+) showed good electrochemical and photochemical activities. In a flow system, the eluted alkaloids were oxidized on the modified GCE, and reacted with immobilized Ru(bpy)(3)(2+) at the potential of +1.50V (versus Ag/AgCl). The luminescence with lambda(max) 610nm was caused by a reaction of electrolytically formed Ru(bpy)(3)(3+) with an oxidized amine group to generate Ru(bpy)(3)(2+*). The determination limit was 5x10(-6)molL(-1), 8x10(-6)molL(-1), 2.0x10(-5)molL(-1) and 5.0x10(-5)molL(-1) for berberine, trigonelline, allantoin and betaine at S/N 3, respectively. In addition, the factors affecting the determination of the four alkaloids were also studied. | 18,970,736 |
The chemiluminescence mechanism of 3,4-bis(3-indolyl)-1H-pyrrole-2,5-dione, and the characteristics of chemiluminescence developed in the reaction with CH(3)CNH(2)O(2)NaOH. | The chemiluminescence (CL) mechanism of 3,4-bis(3-indolyl)-1H-pyrrole-2,5-dione (IPD) was investigated using liquid chromatography electrospray ionization mass spectrometry (LC-ESI-MS) of the products formed after the IPD CL reaction. We found that IPD produced strong CL via the decomposition of dioxetane formed after oxidation of the maleimide and indole moieties in the presence of CH(3)CN, H(2)O(2) and NaOH. The IPD CL was used for evaluating the antioxidant effect on curcumin and epigallocatechin gallate. | 18,970,740 |
Ion-exclusion/adsorption chromatography of dimethylsulfoxide and its derivatives for the evaluation to quality-test of TiO(2)-photocatalyst in water. | Ion-exclusion/adsorption chromatography of dimethylsulfoxide (DMSO) and its derivatives, i.e., methanesulfinic acid (MSI), methanesulfonic acid (MSA) and sulfuric acid (SA), was developed in order to clear the decomposition mechanism of DMSO on quality-test of TiO(2)-photocatalyst in water. The separation was achieved by the adsorption effect for DMSO and ion-exclusion effect for MSI, MSA and SA under optimum conditions, using a weakly acidic cation-exchange resin column with 20mM succinic acid as the eluent. In this system, DMSO and MSI with UV at 195nm and MSA and SA with conductivity detection were consecutively determined by single injection and single separation column. This method was used to monitor the artificial decomposition of DMSO induced by a photocatalyst. The concentration of DMSO by active oxygens (e.g., OH radical) generated from surface of photocatalyst was found to be decreased through the stoichiometric reaction in the order of MSI, MSA and SA. | 18,970,746 |
Ion-exclusion chromatography with the direct UV detection of non-absorbing inorganic cations using an anion-exchange conversion column in the iodide-form. | An ion-exclusion chromatographic method for the direct UV detection of non-absorbing inorganic cations such as sodium (Na(+)), ammonium (NH(4)(+)) and hydrazine (N(2)H(5)(+)) ions was developed by connecting an anion-exchange column in the I(-)-form after the separation column. For example, NH(4)(+) is converted to a UV-absorbing molecule, NH(4)I, by the anion-exchange column in the I(-)-form after the ion-exclusion separation on anion-exchange column in the OH(-)-form with water eluent. As a result, the direct UV detection of Na(+), NH(4)(+) and N(2)H(5)(+) could be successfully obtained as well as the well-resolved separation. The calibration graphs of the analyte cations detected with UV at 230nm were linear in the range of 0.001-5.0mM. The detection limits at S/N=3 of the cations were below 0.1muM. This method was applied to real water analysis, the determination of NH(4)(+) in river and rain waters, or that of N(2)H(5)(+) in boiler water, with the satisfactory results. This could be applied also to low- or non-absorbing anions such as fluoride or hydrogencarbonate ions by the combination of a weakly acidic cation-exchange resin in the H(+)-form as the separation column and the anion-exchange conversion column. | 18,970,747 |
Rapid determination of bromide in seawater samples by capillary ion chromatography using monolithic silica columns modified with cetyltrimethylammonium ion. | Monolithic silica capillary columns dynamically modified with quaternary ammonium ions were evaluated for the determination of bromide in seawater samples. A quaternary ammonium ion such as cetyltrimethylammonium ion was dynamically introduced onto monolithic silica surfaces. The first layer of the modifier was introduced by electrostatic interaction, whereas the second layer was introduced by hydrophobic interaction. The latter layer worked as the anion-exchange sites. The modified monolithic silica capillary columns could be used for rapid separation of inorganic anions. Separation of authentic mixture of five anions was achieved within a few minutes. The addition of small amount of the modifier in the eluent improved the repeatability of the retention time. Seawater samples could be directly injected onto the prepared capillary columns, and bromide could be determined to be 63mg/L. | 18,970,751 |
Simultaneous preconcentration of uranium(VI) and thorium(IV) from aqueous solutions using a chelating calix[4]arene anchored chloromethylated polystyrene solid phase. | A new chelating polymeric sorbent is developed using Merrifield chloromethylated resin anchored with calix[4]arene-o-vanillinsemicarbazone for simultaneous separation and solid phase extractive preconcentration of U(VI) and Th(IV). The "upper-rim" functionalized calix[4]arene-o-vanillinsemicarbazone was covalently linked to Merrifield resin and characterized by FT-IR and elemental analysis. The synthesized chelating polymeric sorbent shows superior binding affinity towards U(VI) and Th(IV) under selective pH conditions. Various physico-chemical parameters that influence the quantitative extraction of metal ions were optimized. The optimum pH range and flow rates for U(VI) and Th(IV) were 6.0-7.0 and 1.0-4.0mlmin(-1) and 3.5-4.5 and 1.5-4.0mlmin(-1), respectively. The total sorption capacity found for U(VI) and Th(IV) was 48734 and 41175mugg(-1), respectively. Interference studies carried out in the presence of diverse ions and electrolyte species showed quantitative analyte recovery (98-98.5%) with lower limits of detection, 6.14 and 4.29mugl(-1) and high preconcentration factors, 143 and 153 for U(VI) and Th(IV), respectively. The uptake and stripping of these metal ions on the resin were fast, indicating a better accessibility of the metal ions towards the chelating sites. The analytical applicability of the synthesized polymeric sorbent was tested with some synthetic mixtures for the separation of U(VI) and Th(IV) from each other and also from La(III), Cu(II) and Pb(II) by varying the pH and sequential acidic elution. The validity of the proposed method was checked by analyzing these metal ions in natural water samples, monazite sand and standard geological materials. | 18,970,761 |
Influence of different extraction methods on the yield and linalool content of the extracts of Eugenia uniflora L. | This work has been developed using a sylvestral fruit tree, native to the Brazilian forest, the Eugenia uniflora L., one of the Mirtaceae family. The main goal of the analytical study was focused on extraction methods themselves. The method development pointed to the Clevenger extraction as the best yield in relation to SFE and Soxhlet. The SFE method presented a good yield but showed a big amount of components in the final extract, demonstrating low selectivity. The essential oil extracted was analyzed by GC/FID showing a large range of polarity and boiling point compounds, where linalool, a widely used compound, was identified. Furthermore, an analytical solid phase extraction method was used to clean it up and obtain separated classes of compounds that were fractionated and studied by GC/FID and GC/MS. | 18,970,765 |
Authentication of vegetable oils on the basis of their physico-chemical properties with the aid of chemometrics. | In food production, reliable analytical methods for confirmation of purity or degree of spoilage are required by growers, food quality assessors, processors, and consumers. Seven parameters of physico-chemical properties, such as acid number, colority, density, refractive index, moisture and volatility, saponification value and peroxide value, were measured for quality and adulterated soybean, as well as quality and rancid rapeseed oils. Chemometrics methods were then applied for qualitative and quantitative discrimination and prediction of the oils by methods such exploratory principal component analysis (PCA), partial least squares (PLS), radial basis function-artificial neural networks (RBF-ANN), and multi-criteria decision making methods (MCDM), PROMETHEE and GAIA. In general, the soybean and rapeseed oils were discriminated by PCA, and the two spoilt oils behaved differently with the rancid rapeseed samples exhibiting more object scatter on the PC-scores plot, than the adulterated soybean oil. For the PLS and RBF-ANN prediction methods, suitable training models were devised, which were able to predict satisfactorily the category of the four different oil samples in the verification set. Rank ordering with the use of MCDM models indicated that the oil types can be discriminated on the PROMETHEE II scale. For the first time, it was demonstrated how ranking of oil objects with the use of PROMETHEE and GAIA could be utilized as a versatile indicator of quality performance of products on the basis of a standard selected by the stakeholder. In principle, this approach provides a very flexible method for assessment of product quality directly from the measured data. | 18,970,766 |
Investigation of the association behaviors between biliverdin and bovine serum albumin by fluorescence spectroscopy. | The interaction between biliverdin and bovine serum albumin (BSA) has been studied by steady fluorescence spectroscopy, synchronous fluorescence and resonance light scanning spectra. The binding of biliverdin to BSA quenches the tryptophan residue fluorescence and the results show that both static and dynamic quenching occur together with complex formation. The binding constant and binding sites of biliverdin to BSA at pH 7.1 are calculated to be 3.33x10(8)L/mol and 1.54, respectively, according to the double logarithm regression curve. In addition, the distance between the biliverdin and BSA is estimated to be 1.25nm using Föster's equation on the basis of the fluorescence energy transfer. Furthermore the synchronous fluorescence spectra show that the microenvironment of the tryptophan residues has not obvious changes, which obeys the phase distribution model. Finally, the thermodynamic data show that biliverdin molecules enter the hydrophobic cavity of BSA via hydrophobic interaction. | 18,970,778 |
Probing trace Pb(2+) using electrodeposited N,N'-(o-phenylene)-bis-benzenesulfonamide polymer as a novel selective ion capturing film. | A novel film modified electrode for the determination of trace lead was developed in this work. The modified electrode was prepared by the electropolymerization of N,N'-(o-phenylene)-bis-benzenesulfonamide (PBSA) as the ion capturing reagent to create the functional film. The modified electrode shows a high selectivity towards Pb(2+) over interfering cations, e.g. Cu(2+), Cd(2+), Co(2+), Ni(2+), Zn(2+), Cr(2+), and the calibration curve was linear in the concentration range of 2.0x10(-9) to 1.0x10(-7)M with correlation coefficient of 0.999. For 20min accumulation, detection limit of 1.0x10(-9)M was obtained at the signal to noise ratio of 3. Analytical availability of the modified electrode was demonstrated by the application for samples from pond water. | 18,970,788 |
Gold colloid-bienzyme conjugates for glucose detection utilizing surface-enhanced Raman scattering. | It is difficult to detect glucose by surface-enhanced Raman spectroscopy (SERS) due to the small normal Raman cross-section and the weak adsorption of glucose molecules on the surface of noble metal. A simple and fast method is proposed in this paper for the detection of glucose based on SERS signal of the enzyme reaction product and the difficulties have been circumvented. Gold colloids modified by horseradish peroxidase and glucose oxidase (HRP/GOD-gold colloids) are added to the mixture of o-phenylenediamine and glucose, and the resulting solution is allowed to react at room temperature for 5min. Azoaniline, an azo compound with strong Raman scattering, is generated and the Raman scattering of this reaction product is enhanced when adsorbed on gold colloids. The intensity of the SERS spectrum is used for assessment of glucose content. The dynamic signal range provided by this analytical system is 0.50-32mM, which covers the normal clinical range for glucose in blood from 3.5 to 6.1mM. The detection limit is about 0.46mM. The interference effect of several proteins on glucose detection is also investigated and has shown to have no effect on the measurement of glucose by the described technique. | 18,970,804 |
A simple taste analyzing system design for visual and quantitative analysis of different tastes using multi-array chemical sensors and pattern recognition techniques. | In this paper, we describe design of a simple taste analyzing system using sensory system based on a multi-array chemical sensor (MACS) and personal digital assistant (PDA) for visual and quantitative analysis of different tastes using pattern recognition techniques. The sensory system is communicated with PDA, which has several interesting benefits for data analysis and display, via wireless using the Bluetooth. A various pattern recognition techniques are adapted including spider map, principal component analysis (PCA) and fuzzy C-means (FCM) algorithm to classify visually data patterns detected by the sensory system. The proposed techniques can be determined the cluster centers and membership grade of patterns through the unsupervised way. The membership grade of an unknown pattern, which does not shown previously, can be visually and analytically determined. Throughout the experimental trails, the taste analyzing system is demonstrated robust performance through data acquisition via wireless communication and visual and quantitative analysis of different tastes for the liquids. The system, which is implemented as a simple hand-held taste analyzing instrument, can be applicable to on-site taste monitoring. | 18,970,806 |
Conversion of chromium(III) propionate to chromium(VI) by the Advanced Oxidation Process Pretreatment of a biomimetic complex for metal analysis. | The use of H(2)O(2) and UV irradiation to remove organic ligands in a chromium(III) complex for the subsequent chromium analysis is reported. The Advanced Oxidation Process (AOP) using a 5.5-W UV lamp, H(2)O(2) and Fe(2+)/Fe(3+) as catalyst (photo Fenton process) was found to give complete and quantitative Cr(III)-->Cr(VI) conversion and removal of ligands in chromium(III) propionate [Cr(3)O(O(2)CCH(2)CH(3))(6)(H(2)O)(3)]NO(3), a biomimetic chromium species, as subsequent chromium analyses by the 1,5-diphenylcarbazide method and atomic absorption revealed. The current process eliminates the need for mineralization and/or dissolution of the matrix in order to remove the organic ligand, the traditional pretreatments of a sample for metal analysis. Studies to optimize the conditions for the oxidation processes, including the use of Fe(2+)/Fe(3+) catalyst, length of UV irradiation, H(2)O(2) concentration, pH, power of UV lamp, and reactor size, are reported. | 18,970,825 |
Identification and distribution of contamination sources in the Ebro river basin by chemometrics modelling coupled to geographical information systems. | Identification of the main contamination sources of heavy metals, organic compounds and other physicochemical parameters in Ebro river surface waters and description of their temporal and spatial distributions, are analyzed using chemometrics and geostatistical methods. Historical data available from the Confederación Hidrográfica del Ebro (CHE), which is the organization in charge of the management of the Ebro river basin; covering different years since 1992 for water, sediments and fish samples are investigated. Due to the great amount of data in these databases and to their complexity, chemometrics modelling (using principal components analysis, PCA) coupled to geographical information systems (GIS) is proposed to evaluate the environmental quality of the Ebro river basin. | 18,970,828 |
Occurrence of betablockers in effluents of wastewater treatment plants from the Lyon area (France) and risk assessment for the downstream rivers. | Five betablockers (oxprenolol, metoprolol, propranolol, bisoprolol, betaxolol) were analysed in effluents collected over a 3-month period from wastewater treatment plants (WTP) from the Lyon area in France. The analytical protocol consisted of solid phase extraction of the dissolved aqueous phase on HLB cartridges and analysis by gas chromatography coupled with mass detection (GC-MS) after derivatization. Concentrations of metoprolol, propranolol and bisoprolol varied from 45 to 2838ng/L whereas oxprenolol and betaxolol were never detected in these effluent samples. A high variability of betablockers concentrations and fluxes was observed between WTP effluents and within each WTP over the time period studied. Considering a flux per person for a dry weather period, Fontaine plant was pointed out as the less efficient WTP, which might be explained by its type of treatment (biological aerated filters). But we need additional analysis of effluent and influent waters to confirm this hypothesis. A tentative approach of local environmental risk assessment of propranolol based on the calculation of PEC/PNEC (predicted environmental concentration/predicted non effect concentration) ratio approach lead us to conclude on a negligible risk for the downstream rivers (Rhône river at Ternay and Saône river at Couzon Mt d'Or). | 18,970,833 |
Determination of total water content in inulin using the volumetric Karl Fischer titration. | A new sample preparation method for the water content determination of inulin by volumetric Karl Fischer (KF) titration was developed and compared to the usual method of introducing the sample directly in the methanol-based working medium, modified or not by formamide (1:3, v/v) in order to increase sample solubility. In the proposed method, inulins were externally prepared by dissolving them in pure formamide (2.5:7.5, w/w). The time of analysis of the liquid/liquid reaction of the new method between the dissolved sample and the reaction medium is about 1-2min, while the usual KF method is stopped after the 10min delay time. The developed method permits the determination of water included in the crystals of the sample, confirmed by analysing both crystalline and amorphous inulin samples. Another advantage of this new method is its applicability for the water content determination of other polysaccharides that are not readily soluble in the working medium. Moreover, water content determination can be done by any type of volumetric KF titrator, as this proposed technique is not dependent on any additional tools such as a built-in homogeniser or a heatable titration beaker. | 18,970,874 |
Determination of epichlorohydrin in water and sewage samples. | The simple, quick and effective methods for the analysis of epichlorohydrin (ECH) in water and sewage samples with the use of gas chromatography have been presented. From among all the methods developed, the procedures for monitoring drinking-water quality and the methods which allow the determination of epichlorohydrin in sewage samples have been selected. The limits of ECH detection have been determined by direct aqueous injection (DAI) into the chromatographic column and an analysis with the application of a flame ionization detector (FID), a mass spectrometry detector (MS), an electron capture detector (ECD) and atomic emission detection (AED) detectors. The method allows the determination of ECH in water samples at the concentration level of 0.1mgl(-1). Moreover, the developed methods of water samples preparation for chromatographic analysis using the following extraction methods: headspace (HS), stripping with adsorption on solid phase, liquid-liquid extraction (LLE), solid phase extraction (SPE) and solid phase microextraction (SPME) have been evaluated. The limits of ECH detection for each procedure with the application of gas chromatography (GC) combined with various detectors have been determined and their statistical evaluation has been presented. The SPME method allowed us to determine ECH in water samples at the concentration levels of 1.0ngl(-1). The results of studies on the choice of the selective methods allowing ECH analysis in sewage samples have been demonstrated. The applied SPME method was found to be a quick and effective technique to determine micro trace amounts of ECH in samples containing high amounts of various organic compounds. | 18,970,879 |
Evaluation of two commercial capillary columns for the enantioselective gas chromatographic separation of organophosphorus pesticides. | The separation of the enantiomers of 13 organophosphorus pesticides (OPPs) has been investigated by gas chromatography (GC) with flame ionisation detection (FID) using two different commercially available chiral columns, Chirasil-Val (l-valine-tert-butylamide) and CP-Chirasil-Dex CB (heptakis (2,3,6-tri-O-metil)-beta-cyclodextrin). Using the Chirasil-Val column no chiral resolution was obtained for the OPPs investigated under any tested experimental condition. The use of the CP-Chirasil-Dex CB stationary phase enabled good individual enantiomeric separation of two OPPs, ruelene and trichlorfon and partial separation of naled, chloretoxyphos, isophenphos and metamidophos. Also, the obtained chromatographic results showed that Chirasil-Dex could resolve enantiomers through the combination of different mechanism (e.g. formation of inclusion complexes and/or interactions outside the cyclodextrin cavity). Under optimised conditions, precision, linearity range and detection limits were evaluated for the enantiomers of ruelene and trichlorfon using CP-Chirasil-Dex CB column and electron capture detection (ECD). By using the GC-ECD method the enantiomers of these OPPs could be satisfactorily detected at very low concentration levels. The detection limits observed were 1.5ngmL(-1) and 11.5ngmL(-1) for the enantiomers of trichlorfon and ruelene, respectively. | 18,970,881 |
Kinetics of oil saponification by lead salts in ancient preparations of pharmaceutical lead plasters and painting lead mediums. | Lead soaps can be found in archaeological cosmetics as well as in oil paintings, as product of interactions of lead salts with oil. In this context, a better understanding of the formation of lead soaps allows a follow-up of the historical evolution of preparation recipes and provides new insights into conservation conditions. First, ancient recipes of both pharmaceutical lead plasters and painting lead mediums, mixtures of oil and lead salts, were reconstructed. The ester saponification by lead salts is determined by the preparation parameters which were quantified by FT-IR spectrometry. In particular, ATR/FT-IR spectrometer was calibrated by the standard addition method to quantitatively follow the kinetics of this reaction. The influence of different parameters such as temperature, presence of water and choice of lead salts was assessed: the saponification is clearly accelerated by water and heating. This analysis provides chemical explanations to the historical evolution of cosmetic and painting preparation recipes. | 18,970,891 |
The relationship between dysphoria and proneness to hallucination and delusions among young adults. | Previous research suggests that measures of dysphoria relate to positive schizophrenic symptoms. These relationships have rarely been studied within the dimensionality of psychopathology framework. The present study examined the relationship between 3 distinct aspects of dysphoria (depression and state and trait anxiety) and delusion and hallucination proneness in a nonclinical sample of young adults. A total of 472 participants were assessed on measures of dysphoria and delusion and hallucination proneness. Correlation analyses revealed significant associations between both anxiety and depression and hallucination and delusion proneness, suggesting that the association between dysphoria and positive symptoms is also present at a nonclinical level. Partial correlations, and hierarchical regression models, suggest an independent contribution of depression, over anxiety, in influencing hallucination and delusional proneness. The results are discussed in the framework of the cognitive account of schizophrenia and the dimensional model of psychopathology. | 18,970,902 |
Clinical characteristics of trichotillomania with trichophagia. | Little is known about trichophagia in individuals with trichotillomania. Although studies have mentioned the behavior, no previous studies have examined clinical correlates of trichophagia. We examined the clinical correlates of trichophagia in 68 subjects with Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, trichotillomania (85.3% females; mean age, 35.0 +/- 12.5). Comorbidity data were obtained with the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Trichotillomania severity was assessed with the Psychiatric Institute Trichotillomania Scale and the Massachusetts General Hospital Hairpulling Scale. Social/occupational functioning was examined using the Sheehan Disability Scale. All variables were compared in trichotillomania subjects with and without trichophagia. Of the 68 subjects with trichotillomania, 14 (20.6%; 95% confidence interval, 12.7%-31.6%) reported current trichophagia, and an additional 9 (13.2%) ate their hair or the root episodically. There were far more similarities than differences in trichotillomania subjects with current trichophagia and those without, although those with trichophagia were significantly more likely to be male (P = .013) and have more severe trichotillomania (according to the Massachusetts General Hospital Hairpulling Scale) (P = .010). These preliminary results suggest that trichophagia is not uncommon in individuals with trichophagia. Subjects with and without trichophagia were similar in most domains that were examined. | 18,970,906 |
Primary paratesticular neuroblastoma: a case report and review of literature. | Only 4 infants with primary paratesticular neuroblastoma have been previously described. To the author's knowledge, this case would be the first report of a child who is older than 1 year whose lesion is in his right hemiscrotum. After simple tumorectomy was performed; he was tumor free at 4 years of follow-up. Patients older than 1 year with localized primary paratesticular neuroblastoma may have good prognosis after simple tumorectomy without further therapy. | 18,970,922 |
Synchronous bilateral Wilm's tumor with complete radiographic response managed without surgical resection: a report from the National Wilm's Tumor Study 4. | We reviewed the long-term local tumor control in patients with bilateral Wilm's tumor (BWT) who received no definitive surgical therapy to one kidney after complete radiographic resolution after initial chemotherapy. National Wilm's Tumor Study 4 (NWTS-4) enrolled 3335 patients (pts) during the period August 1986 to August 1994. There were 188 pts with BWT or 5.6% of the total enrolled. The treatment records and imaging reports were reviewed to ascertain those children who had documented tumors without definitive surgical therapy after initial treatment. Patients who did not have renal surgery because of progression of tumor were excluded from this study. Eleven children had no definitive surgical treatment of renal lesions in one kidney (right, 6; left, 5) after initial treatment with chemotherapy and/or radiation therapy. The pretreatment size of the lesions were less than 3 cm (4 pts), 3 to 6 cm (5 pts), more than 6 cm (1 pt), and unknown (1 pt). Prechemotherapy biopsy was performed in 6 of 11 patients. Lesions were less than 3 cm (1 pt), 3 to 6 cm (3 pts), more than 6 cm (1 pt), and unknown (1 pt). Four biopsy specimens showed favorable Wilm's histologic findings. One lesion (4 cm) showed an intralobar nephrogenic rest, another lesion of unknown size was read as favorable histologic findings vs perilobar nephrogenic rest. Biopsy was not performed on 5 lesions (4 pts, <1 cm; 1 pt, 3cm). Only 2 children in this study received radiation treatment. One child received 1050 cGy whole abdominal radiation, and 1 child received 1060 cGy to the left flank postnephrectomy. Radiation therapy was not given to any patient because of failure of the tumor to respond to chemotherapy. Five patients received treatment regimen EE-4A, dactinomycin, and vincristine. The duration of therapy ranged from 24 to 102 weeks for an average of 55.6 weeks. Three patients received treatment regimen DD-4A, dactinomycin, vincristine, and doxorubicin for 28, 52, and 52 weeks, respectively. Three patients received 2 separate regimens of chemotherapy. One child was treated with dactinomycin, vincristine, and cyclophosphamide for 60 weeks and then received regimen EE-4A for 24 weeks. Another patient received regimen EE-4A for 16 weeks and then regimen DD4-A for 36 weeks. One child received regimen EE-4-A for 12 weeks and then regimen DD4A for 40 weeks. Management of the contralateral kidney was complete nephrectomy in all 11 patients. There were no local relapses in the renal tumor bed. All patients were alive at a median follow-up of 9 years (range, 9 months to 15 years). Children with synchronous BWT or Wilm's tumor and contralateral nephrogenic rests that have radiographic resolution, after initial treatment, have a low risk for local relapse. These children should be followed by serial imaging. | 18,970,928 |
Unusual variants of congenital pouch colon with anorectal malformations. | Anorectal malformations are common worldwide. Several classifications were used to describe the different types, but in spite of this, there are rare variants. This report describes 2 unusual cases of congenital pouch colon and anorectal malformations. | 18,970,947 |
Endoscopic management of recurrent tracheoesophageal fistula with trichloroacetic acid chemocauterization: a preliminary report. | Open repair with a second thoracotomy is technically challenging and has a high risk of complications for the treatment of a recurrent tracheoesophageal fistula (RTEF). Therefore, less invasive endoscopic techniques have been developed. Here, we report on the chemocauterization with trichloroacetic acid (TCA) technique for endoscopic management of RTEF. Three patients who had an open repair with thoracotomy for congenital tracheoesophageal fistula and were diagnosed with RTEF were included in this study. Rigid ventilating bronchoscopy with telescopic magnification was used to evaluate and manage the RTEF. After identification of the fistula opening, a 50% TCA-soaked small cotton ball was applied in the opening 3 times during each session. The mean number of procedures was 3.3, and the fistulae were closed in all cases. Closure of the fistula was confirmed by esophagogram and/or bronchoscopy. There were no postoperative complications. The results of this study showed that chemocauterization with TCA can be safe and effective for the management of RTEF. | 18,970,956 |
The brachial artery-brachial vein fistula: expanding the possibilities for autogenous fistulae. | The National Kidney Foundation Dialysis Outcomes and Quality Initiative recommends autogenous access for new dialysis procedures. The patient requiring hemodialysis with inadequate superficial arm veins represents a formidable challenge to the surgeon. Our objective is to describe results with an alternative access procedure, the autogenous brachial-brachial artery (ABBA) access in patients with inadequate superficial arm veins. One surgeon created 163 new dialysis accesses in 122 patients during 40 consecutive months at a university hospital. There was 97% patient follow-up. All patent but diminutive superficial arm veins as judged by preoperative ultrasound were explored. Arms with inadequate veins at exploration or arms with thrombosed veins on ultrasound received either prosthetic or ABBA procedures. Upper-arm access was often staged, involving a second "superficialization" procedure. This is a retrospective case series based on a comprehensive medical record review. Cox proportional hazards models were used to compare access patency for individual as well as multiple factors suspected or known to influence dialysis access outcomes. Society for Vascular Surgery reporting guidelines were used except where specifically noted and justified otherwise. One hundred thirty-five autogenous and 28 prosthetic dialysis operations were performed. Primary patency for all access procedures at 12, 24, and 36 months was 58%, 50%, and 38%, respectively. Primary assisted patency for all access procedures at 12, 24, and 36 months was 97%, 91%, and 85%, respectively. Secondary patency at 12, 24, and 36 months was 99%, 97%, and 97%, respectively. Finally, functional patency at 12, 24, and 36 months was 71%, 67%, and 44.0%, respectively. Of the 122 patients, 70 patients received either ABBA or prosthetic access. ABBA out-performed prosthetic access in terms of primary patency (hazard ratio for prosthetic vs ABBA: 4.21 (95% confidence interval [CI]: 1.49, 11.91) and functional patency (hazard ratio for prosthetic vs ABBA: 6.27 95% CI: 1.24-31.72) in patients referred early. Functional patency was more likely to be compromised in elderly patients and in patients with hypercoagulable diagnoses. Autogenous brachial-brachial access for dialysis out-performed prosthetic access with respect to primary and functional patency in patients referred early without differences in overall complications. | 18,971,036 |
Polydeoxyribonucleotide (PDRN) restores blood flow in an experimental model of peripheral artery occlusive disease. | This study investigated whether polydeoxyribonucleotide (PDRN) may be efficacious in the treatment of peripheral artery occlusive diseases, which are a major cause of morbidity in Western countries and still lack standardized treatment. We investigated the effects of PDRN, a mixture of deoxyribonucleotides, in an experimental model of hind limb ischemia (HLI) in rats to stimulate vascular endothelial growth factor (VEGF)-A production and to avoid critical ischemia. The femoral artery was excised to induce HLI. Sham-operated on rats (sham HLI) were used as controls. Animals were treated daily with intraperitoneal PDRN (8 mg/kg) or its vehicle. Animals were euthanized at day 7, 14, and 21 after the evaluation of blood flow by laser Doppler. Dissected muscles were used to measure VEGF-A messenger RNA (mRNA) and protein expression, to evaluate edema, and to assess histologic damage. Administration of PDRN dramatically increased VEGF mRNA throughout the study (day 14: HLI, 7 +/- 2.2 n-fold/beta-actin; HLI + PDRN, 13.3 +/- 3.8 n-fold/beta-actin; P < .0001) and protein expression (HLI, 11 +/- 3.4 integrated intensity; HLI + PDRN, 16 +/- 3.8 integrated intensity; P < .0001). The compound stimulated revascularization, as confirmed by blood flow restoration (P < .005 vs HLI + vehicle), and blunted the histologic damage and the degree of edema. PDRN did not modify VEGF-A expression and blood flow in sham HLI animals. Furthermore, the concomitant administration of 3,7-dimethyl-1-propargilxanthine (DMPX), a selective adenosine A(2A) receptor antagonist, abolished the positive effects of PDRN, confirming that PDRN acts through this receptor. These results led us to hypothesize a role for PDRN in treating peripheral artery occlusive diseases. | 18,971,038 |
Successful treatment tailored to each splanchnic arterial lesion due to segmental arterial mediolysis (SAM): report of a case. | Segmental arterial mediolysis (SAM) is a rare condition characterized by splanchnic arterial catastrophe caused by mediolysis. We report a 59-year-old man with a ruptured splenic arterial aneurysm who was successfully treated by coil embolization. He underwent additional resection of large gastroepiploic and residual splenic aneurysms. Pathological examination showed mediolysis and tearing, compatible with SAM. Furthermore, he developed acute dissection of the superior mesenteric artery (SMA) one and a half years later, demonstrated by computed tomography. This report demonstrates that SAM is characterized by multiple lesions of the splanchnic arteries at different times, and requires treatment suited to the lesions, including careful long-term observation. | 18,971,044 |
The spiral glenohumeral ligament: an open and arthroscopic anatomy study. | The purpose of this study was to visualize arthroscopically and to describe the micro- and macroscopic anatomy of the poorly known ligament of the anterior capsule of the glenohumeral joint: the so-called ligamentum glenohumerale spirale (spiral GHL). Twenty-two fresh shoulder joints were dissected, and the anatomy of the anterior capsular structures (the spiral GHL, the middle glenohumeral ligament [MGHL], and the anterior band as well as the axillary part of the inferior glenohumeral ligament [AIGHL and AxIGHL, respectively]) was investigated. For arthroscopic visualization, 30 prospective arthroscopic clinical cases and 19 retrospective video clips of the patients who had an arthroscopic shoulder procedure with a normal subscapularis tendon, labrum, and anterior joint capsule were evaluated. The spiral GHL and the AxIGHL were present in all 22 shoulder specimens. The AIGHL was not recognizable on the extra-articular side of the joint capsule. The MGHL was absent in 3 shoulder specimens (13.6%). Arthroscopically, the spiral GHL was found in 22 (44.9%), the MGHL in 43 (87.8%), and the AIGHL in 46 (93.9%) of the cases. The spiral GHL arose from the infraglenoid tubercle and the triceps tendon and inserted together with subscapularis tendon onto the lesser tubercle of the humerus. Our results suggest that extra-articular structure of the spiral GHL is consistently recognizable, the upper part of which can be arthroscopically identified. Advanced anatomic knowledge of the spiral GHL helps the clinician better understand the normal anatomy of the shoulder joint and also helps to differentiate it from pathologic findings of the patient. The biomechanical importance of the spiral GHL and its connection with shoulder pathology remains to be determined in further studies. | 18,971,058 |
Assessment and augmentation of symptomatic anteromedial or posterolateral bundle tears of the anterior cruciate ligament. | The anterior cruciate ligament (ACL) consists of 2 anatomic and functional bundles, the anteromedial (AM) and posterolateral (PL) bundle. Depending on the mechanism of injury, there are different injury patterns to the AM and PL bundles, demonstrating a wide spectrum of partial ACL tears. Clinical interest has recently focused on establishing pre- and intraoperative ways of assessing the different types of symptomatic partial ACL injuries in order to perform an individual ACL augmentation according to the specific injury pattern. Theoretically, sparing the intact parts of the ACL may increase vascularization and proprioception, may optimize the accuracy of the ACL reconstruction, and may result in better stability and improved clinical outcome for the patient. However, an isolated reconstruction of the AM or PL bundle is an advanced arthroscopic procedure that requires a precise pre- and intraoperative diagnostic assessment of the injury pattern, an exact arthroscopic knowledge of the anatomic insertion sites, a careful debridement, and bone tunnel placement while preserving the intact parts of the ACL. This article will present the concept of partial ACL tears and will describe the clinical, radiologic, and arthroscopic assessment and the arthroscopic technique of isolated AM or PL bundle augmentation. | 18,971,061 |
Assessing health and safety in early care and education programs: development of the CCHP health and safety checklist. | To assess health and safety in early care and education (ECE) programs, an objective, standardized instrument was developed based on the recommended national health and safety standards. The California Childcare Health Program Health and Safety Checklist was developed by conducting a literature review, identifying a gold standard, revising and updating the original Checklist, consulting with an advisory group, and pilot testing the Checklist. The Checklist included 66 items grouped into 10 subscales, and each item was rated on a three-point scale: meeting, partially meeting, or not meeting national standards. Face, content, and construct validity along with measures of reliability, inter-rater reliability, and internal consistency were established. The Checklist was completed in 127 ECE centers. The highest subscale score was for emergency preparedness and the lowest was for handwashing routines and equipment maintenance. Cronbach's alpha subscale scores ranged from moderate to strong (0.27 to 0.70). The Checklist provides valid and reliable information to assess adherence to key national health and safety standards and objective data to develop intervention programs to improve health and safety in ECE programs. | 18,971,083 |
[Urological emergencies at the Dakar university teaching hospital: epidemiological, clinical and therapeutic features]. | To present the epidemiological, clinical and therapeutic features of the urological emergencies in Senegal, West Africa. The authors conducted a 20 months retrospective study that analyzed the epidemiological, clinical and therapeutic features of all urological emergencies admitted to the urology department of the university teaching hospital Aristide-Le-Dantec (Dakar). There were 1237 urological emergencies. The mean age of the patients was 58.8 years (range one month-94 years). The sex ratio (M/F) was 20.32. These patients had an age equal to or higher than 60 years in 50.7% of the cases. The most frequent illness was urinary retention (53%) and genitor-urinary system infectious, which represented as a whole 16.4% of the cases. The gangrenes of male external genitalia (Fournier's gangrene) accounted for 4.1% of the cases and the priapism 1.3%. In emergency, 331 surgical operations were performed. The most performed procedures were the installation of a suprapubic catheter (59.8%) and debridement of a gangrene of male external genitalia (15.4%). The most frequent urological emergency in our country was the acute urinary retention. Some serious illness like gangrene of male external genitalia (Fournier's gangrene) and priapism are not rare there. | 18,971,107 |
[Using the intersitital cystitis new diagnostic criteria in daily practice: about 156 patients]. | To describe the characteristics of patients with interstitial cystitis and to determine what proportion of those patients met the European Society for the Study of interstitial cystitis/painful bladder syndrome 2005 (ESSIC IC/PBS) definition and how those who met the definition differed from those who did not. A total of 156 patients diagnosed as having an interstitial cystitis were followed in our institution between 1997 and 2007. The diagnosis was suggested by the clinical history and confirmed on the basis of clinical symptoms, voiding diary findings, Pearson's test, O'Leary-Sant questionnaire, cystoscopy and hydrodistension and by the exclusion of other significant pathologies. The patients were evaluated in a prospective manner. We studied the demographics of our patients, described the common clinical presentation. We applied the ESSIC 2005 definition of CI/PBS on this population and found the proportion that meets this definition. The sex ratio F/M was 8:1. The patients were symptomatic for a median of 7.3 years before IC is diagnosed. The most common symptom was pain which was found in 100% of patients, frequency was found in 82% and nocturia in 62%. The common sites where pain was localized were suprapubic in 80%, perineal in 70% and genital in 40%. A burning sensation was found in 55% of patients. Hunner's lesion was found in three patients. The cystoscopy and hydrodistension revealed glomerulations in 88.4% of patients. The ESSIC 2005 definition identified only 74% of the 156 patients diagnosed as having IC/PBS. The symptoms in interstitial cystitis are variable. The ESSIC 2005 definition may not be sufficiently sensitive excluding over 26% of patients diagnosed as having IC. Minor modifications (pain type and location) of the definition appeared to increase its sensitivity. | 18,971,112 |
Cancer as an endocrine problem. | Many of the most common cancers that blight our societies are very rare in other large populations in the world; studies of migrants exclude a simple genetic explanation for these wide geographical variations and imply that environmental exposures are key determinants of the development of these cancers. The most heavily implicated factor is nutrition. There are many other clinical indicators that nutrition, energy balance and metabolic status are perturbed in large numbers of individuals in 'Westernized' societies. Many of the tissue morbidities associated with metabolic disturbance are mediated by the consequent hormonal perturbations, and it is likely that these endocrine controls also mediate the effects of nutrition and metabolic status on the development of many clinical cancers. The recent characterization of the genomic landscape of breast and colorectal cancers have established that a few cell signalling pathways are critical for the clinical course of these cancers, in particular cell signalling pathways that are also central to the regulation of cell metabolism. These signalling pathways are normally under hormonal control, and again this evidence suggests that these hormonal controls may determine the context that is permissive for the progression of clinical cancers. This new understanding indicates that many cancers are potentially preventable, and that nutrition, metabolic and endocrine interventions are the most promising strategies for disease prevention. | 18,971,117 |
Nutrition, metabolic factors and cancer risk. | Excess body weight (adiposity) and physical inactivity are increasingly being recognized as major nutritional risk factors for cancer, and especially for many of those cancer types that have increased incidence rates in affluent, industrialized parts of the world. In this review, an overview is presented of some key biological mechanisms that may provide important metabolic links between nutrition, physical activity and cancer, including insulin resistance and reduced glucose tolerance, increased activation of the growth hormone/IGF-I axis, alterations in sex-steroid synthesis and/or bioavailability, and low-grade chronic inflammation through the effects of adipokines and cytokines. | 18,971,118 |
Exogenous and endogenous hormones and breast cancer. | Exposure to higher levels of both exogenous and endogenous hormone is associated with breast cancer risk. Because of the association between breast cancer and HRT, only the minimal duration of HRT use is recommended for symptom control, and it is not recommended for chronic disease management. Current research issues include the role of progestins, other types of HRT, duration of unopposed estrogen use, and characteristics of cancers that develop on HRT. Circulating sex steroid levels are associated with breast cancer risk, but multiple issues need to be addressed before they are used routinely in clinical practice. Current research issues include measurement of levels for routine clinical practice, integration with standard breast cancer risk models and genetic polymorphism data, and applicability to estrogen-receptor-negative cancers. | 18,971,119 |
Vitamin D and breast cancer risk. | In addition to its important role in the maintenance of the skeleton, there is mounting evidence that vitamin D has effects on other body systems, and that adequate supplies of vitamin D are likely to be required for optimal health. Vitamin D is obtained both from dietary sources and from cutaneous synthesis with exposure to sunlight. Some epidemiological studies have indicated that vitamin D deficiency and decreased exposure to solar UVB radiation increase the risk of some cancers, including breast cancer. The active metabolite of vitamin D, 1,25-dihydroxy-vitamin D(3), is synthesized primarily in the kidney, and has been shown in laboratory studies to have potent anti-proliferative effects on breast cancer cells. Normal and neoplastic breast tissues contain the vitamin D receptor, and gene ablation studies have implicated the receptor in normal breast development. Several polymorphisms have been identified in the vitamin D receptor gene, and these have been associated with risk of breast cancer in some studies. Local synthesis of 1,25-dihydroxyvitamin D(3) in breast tissue may contribute to maintenance of normal cell function, which could be impaired in vitamin D deficiency. | 18,971,120 |
Evaluation and treatment of menorrhagia in an adolescent population. | Bleeding in adolescence is a common but, potentially, difficult condition to manage. Adolescents present with unique issues related to their age, involvement of family members, different differential diagnosis when compared to an older populations, and challenges associated with their evaluation and treatment. | 18,971,130 |
[Effects of ascorbic acid and citric acid on iron bioavailability in an in vitro digestion/ Caco-2 cell culture model]. | To study the effects of ascorbic acid and citric acid on iron bioavailability using an in vitro digestion/Caco-2 cell culture model and evaluate the validity of this cell model. This model combined in vitro digestion technique with Fe uptake by Caco-2 cells by utilizing an inserted ring attached to a dialysis membrane to simulate the gastrointestinal environment to allow simultaneous food digestion and uptake processes. Ferritin formation in the Caco-2 cells was measured as the indicator of Fe uptake by exposing Caco-2 cells to the digests containing Fe plus ascorbic acid or citric acid. When Fe concentration in the digest was below 100 micromol/L, ferritin formation increased with the Fe concentration in the digest. The iron digest containing ascorbic acid exhibited a significant increase in ferritin formation relative to the iron digest containing citric acid. The model was more sensitive to lower iron concentrations when ascorbic acid was present in the digest, while wider range of iron concentration could be assessed by addition of citric acid. The in vitro digestion/ Caco-2 cell culture model is a valuable tool for iron bioavailability assessment. Ascorbic acid has a stronger effect than citric acid in promoting iron bioavailability. | 18,971,162 |
[Reactive astrocytes and nestin expression in adult rats following spinal cord compression injury]. | To observe the expressions of nestin and glial fibrillary acidic protein (GFAP) and their association with reactive astrocytes following spinal cord injury in adult rats. Adult rats with compression injury of the spinal cord were divided into 7 groups (n=6) and examined at 1, 3, and 5 days and at 1, 2, 4 and 8 weeks after the injury. The recovery of the locomotor function after the injury was evaluated with Basso, Beattie and Bresnahan (BBB) scale, and the degree and scope of the spinal injury were assessed using toluidine blue staining. Immunohistochemistry, double immunofluorescent labeling and an image analysis system were employed to observe nestin and GFAP expression and cell proliferation in different regions of the spinal cord. The bilateral hind limb locomotor function of the rats declined severely 24 h after the spinal cord injury and underwent substantial recovery in 1 or 2 weeks after the injury, but followed by rather slow recovery afterwards. Toluidine blue staining of the spinal cord 24 h after the injury showed significant pathological changes in the neurons. The extension of the tissue injury increased with time till 1 week after the spinal cord injury. The site of injury and the adjacent tissues presented with markedly increased nestin and GFAP expressions 24 h after the injury, and nestin+/GFAP(-) cells dominated in the ependymal region around the central canal, whereas nestin+/GFAP+ dominated in the in other regions, showing significant difference from the control group. Nestin and GFAP expression reached the peak level 3 to 7 days after the injury and declined gradually till reaching nearly the control level at 2 weeks. Compression injury of the spinal cord induces up-regulated expressions of nestin and GFAP, and nestin expression is positively correlated to the reactive astrocytes, which, along with the neural stem cells, respond to spinal nerve injury and possibly play a role in repair of the central nervous system injury. | 18,971,163 |
[Expression of FMNL2 and its relation to the metastatic potential of human colorectal cancer cells]. | To explore the association of FMNL2 expression with the metastatic potential of colorectal cancer cells. FMNL2 mRNA and protein expressions in 6 human colorectal cancer cell lines were detected by real-time RT-PCR and immunohistochemical method, respectively, and analyzed for their correlations to the in vitro invasiveness of the cell lines evaluated by Boyden assay. In SW620 and SW480/M5 cell lines, the expression of FMNL2 was repressed by FMNL2 short hairpin RNA (shRNA), and the changes in the invasiveness of the cells were observed. FMNL2 was highly expressed in SW480/M5, LoVo and SW620 cells derived from metastatic colorectal cancers in comparison with that in LS174T, SW480 and HT29 cells, which were derived from primary colorectal cancers. In vitro analysis of the cell invasiveness demonstrated that SW480/M5, LoVo and SW620 cells had higher invasiveness than LS174T, SW480 and HT29 in vitro. In SW480/M5 and SW620 cells, transfection with FMNL2 shRNA resulted in significantly lowered cell invasiveness. FMNL2 may play an important role in the invasion and metastasis of colorectal cancer. | 18,971,169 |
[Post-transplant prophylaxis of the recurrence of lamivudine-resistant YMDD mutant hepatitis B virus in liver recipients]. | To evaluate the prophylactic efficacy of adefovir dipivoxil (ADV) for post-transplant recurrence of hepatitis B virus (HBV) with lamivudine-resistant YMDD mutation in liver recipients. From March 2004 to May 2006, 20 patients with chronic hepatitis B associated with YMDD mutant HBV prior to liver transplantation received treatment with ADV and additional intramuscular hepatitis B immunoglobulin (HBIG) for prevention of post-transplant graft reinfection. The liver function, serum HBsAg, anti-HBs (HBIG), HBeAg, anti-HBc, anti-HBe, HBV DNA and creatinine were examined in all the patients before and after the transplantation. The median follow-up duration of these patients after the transplantation was 33.5 months. Nineteen patients survived and one patient died of recurrent hepatocellular carcinoma. There was significant difference in YMDD mutation rate between the patients with HBV-DNA over 10(6) copies/ml and those with HBV-DNA less than 10(6) copies/ml (12.4% vs 2.5%, P < 0.05). HBV-DNA was undetectable at 4 weeks after the transplantation in 95.0% of the patients (19/20) and at 6 months in one case. No recurrence of hepatitis B was detected by long-term regular testing of HBsAg, HBeAg and HBV-DNA. Serum creatinine increased in 1 case 1 year after the use of ADV. ADV offers protection against recurrence of HBV with YMDD mutation after liver transplantation with only mild nephrotoxicity, but renal function monitoring during the use of ADV is still necessary. | 18,971,179 |
[Pharmacokinetics of nalmefene after a single or multiple intravenous doses in Chinese healthy volunteers]. | To investigate the pharmacokinetics of nalmefene after intravenous administration at a single or multiple doses in Chinese healthy volunteers. This open, randomized clinical trial involved 12 healthy volunteers, who received a single-dose (2 mg) nalmefene injection. Before and at different time points after the injection, blood sample were obtained from the subjects. After the single intravenous dose trial, 8 healthy volunteers received intravenous nalmefene at 2 mg once daily for 6 consecutive days, and the plasma drug concentrations were determined on the morning of days 4, 5 and 6 using liquid chromatography/tandem mass spectrometry and the pharmacokinetic parameters were calculated using PKS program. The main pharmacokinetic parameters of nalmefene (Cmax, Tmax, T1/2, AUC0-48, and AUC0-infinity) after the single intravenous dose were 7.34-/+1.56 microg/L, 0.08 h, 12.01-/+2.20 h, 30.29-/+9.84 microg.L(-1).h, and 32.23-/+9.94 microg.L(-1).h, respectively; the parameters after multiple doses were 8.04-/+1.09 microg/L, 0.08 h, 12.43-/+1.44 h, 33.64-/+9.15 microg.L(-1).h and 35.98-/+9.23 microg.L(-1).h, respectively. The steady-state pharmacokinetic parameters including the degree of fluctuation (DF), AUCss and Cav were 4.69-/+1.29, 19.64-/+6.20 microg.L(-1).h and 1.64-/+0.52 microg/L, respectively. Nalmefene showed similar pharmacokinetics in Chinese healthy volunteers with those in the foreign testees, and can be safely administered in healthy volunteers without producing unmanageable pain. | 18,971,181 |
Diminished NO generation by injured endothelium and loss of macula densa nNOS may contribute to sustained acute kidney injury after ischemia-reperfusion. | In postischemic acute kidney injury (AKI) or acute renal failure, a dissipation of glomerular filtration pressure is associated with an altered renal vascular tone and reactivity, as well as a loss of vascular autoregulation. To test the hypothesis that renal nitric oxide (NO) generation reflects endothelial damage in the kidney after ischemia-reperfusion, we quantified the urinary NO levels and identified the site of its generation in postischemic AKI. Subjects were 50 recipients of cadaveric renal allografts: 15 with sustained AKI and 35 with recovering renal function. Urine and blood samples were obtained after transplant, and intraoperative allograft biopsies were performed to examine NO synthases (NOSs) in the kidney. In the sustained AKI group, urinary nitrite and nitrate excretion (in mumol/g urine creatinine) was lower (12.3 +/- 1.8 and 10.0 +/- 1.4 on postoperative days 0 and 3) than in the recovery group [20.0 +/- 3.6 and 35.1 +/- 5.3 (P < 0.005 vs. sustained AKI on days 0 and 3) on postoperative days 0 and 3]. Endothelial NOS expression diminished from the peritubular capillaries of 6 of 7 subjects in the sustained AKI group but from only 6 of 16 subjects in the recovery group. No differences were observed in the inducible NOS staining pattern between the two groups. Neuronal NOS staining was rarely observed in the macula densae of subjects but was prominent in control tissues. These findings suggest that a diminished NO generation by injured endothelium and loss of macula densa neuronal NOS could impair the vasodilatory ability of the renal vasculature and contribute to the reduction in the glomerular filtration rate in postischemic AKI. | 18,971,208 |
Long-term control of choroidal neovascularisation secondary to angioid streaks treated with intravitreal bevacizumab (Avastin). | To evaluate the efficacy of intravitreal bevacizumab (IB) in the long-term control of subfoveal choroidal neovascularisation (CNV) associated with angioid streaks (AS). Patients with unilateral active CNV associated with AS were enrolled. Exclusion criteria were previous treatment for CNV and comorbidity. Postoperative visual acuity was defined as a gain or loss of two or more lines of best-corrected visual acuity (BCVA). Post-treatment CNV size was dichotomised into "increased," if the CNV area had grown by > or =200 microm(2), and "stable/reduced" if it had decreased by > or =200 microm(2) or had not changed by more than 200 microm(2). Patients were retreated if no further improvement or worsening was noted. Patients were five males and six females aged 33 to 58 years (mean 46.8 (SD 9.2)), who received a mean number of 3.5 (1.3) IB treatments (min: 2; max: 6). The mean retreatment interval was 3 (1.5) months (min: 1; max: 6). The mean follow-up duration was 23.8 (2.9) months. At 20 months all patients had stable/reduced CNV size and stable/improved BCVA. The mean BCVA rose significantly from 0.28 (0.2) at baseline to 0.56 (0.29) at 20 months (p<0.0001). IB is a promising tool for the long-term control of CNV in AS. Further studies are required to validate these findings. | 18,971,232 |
Correlation of visual recovery with presence of photoreceptor inner/outer segment junction in optical coherence images after epiretinal membrane surgery. | To investigate the relationship between the presence of the photoreceptor inner and outer segment (IS/OS) junction and visual acuity after epiretinal membrane (ERM) surgery. Seventy eyes of 70 consecutive patients who had undergone vitrectomy for idiopathic ERM were examined by optical coherence tomography before and 3 and 6 months after surgery. The IS/OS junction was graded into three grades. The time course of recovery of the IS/OS junction, central foveal thickness (CFT) and best corrected visual acuity (BCVA) during the postoperative period was studied. A normal IS/OS junction was detected in 47.1% of the eyes before surgery and in 65.7% at 3 months and 75.7% at 6 months after. There was a significant correlation between the IS/OS grade and BCVA before and at 3 and 6 months after the operation (p = 0.0001, p<0.0001, p<0.0001, respectively). The preoperative IS/OS junction grade correlated significantly with BCVA at 6 months (p = 0.0239). CFT did not correlate significantly with BCVA at 3 and 6 months. The presence of a normal IS/OS junction was associated with good visual acuity after ERM surgery. A normal IS/OS junction probably indicates morphological and functional recovery of the photoreceptors. | 18,971,234 |
Effect of latanoprost and timolol on the histopathology of the human conjunctiva. | To investigate the effect of timolol and latanoprost on the extracellular matrix organisation, inflammatory infiltration, and expression of matrix metalloproteinases (MMPs) and tissue inhibitors of matrix metalloproteinases (TIMPs) in the human conjunctiva. Conjunctival biopsies were obtained from the inferior fornix during routine cataract surgery from 20 patients with primary open-angle glaucoma, who had received a monotherapy either with timolol or latanoprost, and from 10 non-glaucomatous patients. Specimens were investigated by light microscopy, immunohistochemistry using antibodies against MMP-1,-3, TIMP-2,-3 and CD 68 antibodies and by quantitative transmission electron microscopy. The number of collagen fibres was significantly decreased in latanoprost-treated conjunctival specimens compared with timolol-treated eyes (p<0.01) but showed no difference to controls. Amorphous material was increased in both treated groups compared with controls (p<0.001) but was less in latanoprost-treated specimens compared with timolol-treated eyes (p<0.001). Optically clear spaces, probably containing glycosaminoglycans, were significantly reduced in both treated groups-with less of a reduction in latanoprost-compared with timolol-treated eyes (p<0.001). A marked upregulation of MMP-1 and MMP-3 and moderately increased staining for TIMP-2 and TIMP-3 was found in epithelial cells and subepithelial stromal cells of latanoprost-treated eyes. A moderate infiltration with macrophages and inflammatory cells was observed in timolol-treated eyes. Latanoprost-treated conjunctival specimens showed a decreased stromal collagen density and a less pronounced inflammatory infiltration. The upregulation of MMP-1 and MMP-3 in latanoprost-treated eyes might explain the reduced extracellular matrix accumulation in the conjunctival stroma. Therefore, latanoprost therapy might have a more favourable effect on the outcome of glaucoma filtering surgery. | 18,971,237 |
Knowledge-based expert systems and a proof-of-concept case study for multiple sequence alignment construction and analysis. | The traditional approach to bioinformatics analyses relies on independent task-specific services and applications, using different input and output formats, often idiosyncratic, and frequently not designed to inter-operate. In general, such analyses were performed by experts who manually verified the results obtained at each step in the process. Today, the amount of bioinformatics information continuously being produced means that handling the various applications used to study this information presents a major data management and analysis challenge to researchers. It is now impossible to manually analyse all this information and new approaches are needed that are capable of processing the large-scale heterogeneous data in order to extract the pertinent information. We review the recent use of integrated expert systems aimed at providing more efficient knowledge extraction for bioinformatics research. A general methodology for building knowledge-based expert systems is described, focusing on the unstructured information management architecture, UIMA, which provides facilities for both data and process management. A case study involving a multiple alignment expert system prototype called AlexSys is also presented. | 18,971,242 |
Physical activity interventions in the workplace: the rationale and future direction for workplace wellness. | The developing and developed worlds are both facing an obesity epidemic with their workers getting bigger, or to be more specific, fatter. As demonstrated elsewhere in this issue, the individual and societal health and economic costs of obesity and physical inactivity are enormous. There is thus a need for regional, national and global action to combat the issues, with programmes broadly divisible into children and adolescents, the workforce, active aging, healthy aging and a broad cross-cutting agenda that focuses on the built environment. | 18,971,246 |
Palmitoylation of the P2X7 receptor, an ATP-gated channel, controls its expression and association with lipid rafts. | The P2X7 receptor (P2X7R) is an ATP-gated cationic channel expressed by hematopoietic, epithelial, and neuronal cells. Prolonged ATP exposure leads to the formation of a nonselective pore, which can result in cell death. We show that P2X7R is associated with detergent-resistant membranes (DRMs) in both transfected human embryonic kidney (HEK) cells and primary macrophages independently from ATP binding. The DRM association requires the posttranslational modification of P2X7R by palmitic acid. Treatment of cells with the palmitic acid analog 2-bromopalmitate as well as mutations of cysteine to alanine residues abolished P2X7R palmitoylation. Substitution of the 17 intracellular cysteines of P2X7R revealed that 4 regions of the carboxyl terminus domain are involved in palmitoylation. Palmitoylation-defective P2X7R mutants showed a dramatic decrease in cell surface expression because of their retention in the endoplasmic reticulum and proteolytic degradation. Taken together, our data demonstrate that P2X7R palmitoylation plays a critical role in its association with the lipid microdomains of the plasma membrane and in the regulation of its half-life. | 18,971,257 |
The M type K15 protein of Kaposi's sarcoma-associated herpesvirus regulates microRNA expression via its SH2-binding motif to induce cell migration and invasion. | Kaposi's sarcoma (KS) associated herpesvirus (KSHV) is the etiological agent of KS. In vivo, KS is a tumor capable of spreading throughout the body, and pulmonary metastasis is observed clinically. In vitro, KSHV induces the invasiveness of endothelial cells. The KSHV open reading frame K15 is a KSHV-specific gene encoding a transmembrane protein. Two highly divergent forms of K15, the predominant (P) and minor (M) forms (K15P and K15M, respectively), have been identified in different KSHV strains. The two K15 alleles resemble the latent membrane protein 2A (LMP2A) gene of Epstein-Barr virus (EBV) in their genomic locations and protein topology. Also, both K15 proteins have motifs similar to those found in the EBV LMP1 protein. K15 therefore appears to be a hybrid of a distant evolutionary relative of EBV LMP1 and LMP2A. Since both LMP1 and LMP2A proteins are capable of inducing cell motility, we sought to determine whether K15 has similar abilities. In this study, we show that K15M is latently expressed in KSHV-positive PEL cells and knockdown of K15M in PEL cells reduces cell motility. K15M localizes to lysosomal membranes and induces cell migration, invasion, and NF-kappaB (but not AP-1) activity via its conserved SH2-binding motif. K15M also induces the expression of microRNAs miR-21 and miR-31 via this conserved motif, and knocking down both these microRNAs eliminates K15M-induced cell motility. Therefore, K15M may contribute to KSHV-mediated tumor metastasis and angiogenesis via regulation of miR-21 and miR-31, which we show here for the first time to be a specific regulator of cell migration. In light of these findings, the targeting of K15 or the downstream microRNAs regulated by it may represent novel therapies for treatment of KSHV-associated neoplasia. | 18,971,265 |
Mechanism of NS2B-mediated activation of NS3pro in dengue virus: molecular dynamics simulations and bioassays. | The NS2B cofactor is critical for proteolytic activation of the flavivirus NS3 protease. To elucidate the mechanism involved in NS2B-mediated activation of NS3 protease, molecular dynamic simulation, principal component analysis, molecular docking, mutagenesis, and bioassay studies were carried out on both the dengue virus NS3pro and NS2B-NS3pro systems. The results revealed that the NS2B-NS3pro complex is more rigid than NS3pro alone due to its robust hydrogen bond and hydrophobic interaction networks within the complex. These potent networks lead to remodeling of the secondary and tertiary structures of the protease that facilitates cleavage sequence recognition and binding of substrates. The cofactor is also essential for proper domain motion that contributes to substrate binding. Hence, the NS2B cofactor plays a dual role in enzyme activation by facilitating the refolding of the NS3pro domain as well as being directly involved in substrate binding/interactions. Kinetic analyses indicated for the first time that Glu92 and Asp50 in NS2B and Gln27, Gln35, and Arg54 in NS3pro may provide secondary interaction points for substrate binding. These new insights on the mechanistic contributions of the NS2B cofactor to NS3 activation may be utilized to refine current computer-based search strategies to raise the quality of candidate molecules identified as potent inhibitors against flaviviruses. | 18,971,276 |
Genetic history of hepatitis C virus in East Asia. | The hepatitis C virus (HCV), which currently infects an estimated 3% of people worldwide, has been present in some human populations for several centuries, notably HCV genotypes 1 and 2 in West Africa and genotype 6 in Southeast Asia. Here we use newly developed methods of sequence analysis to conduct the first comprehensive investigation of the epidemic and evolutionary history of HCV in Asia. Our analysis includes new HCV core (n = 16) and NS5B (n = 14) gene sequences, obtained from serum samples of jaundiced patients from Laos. These exceptionally diverse isolates were analyzed in conjunction with all available reference strains using phylogenetic and Bayesian coalescent methods. We performed statistical tests of phylogeographic structure and applied a recently developed "relaxed molecular clock" approach to HCV for the first time, which indicated an unexpectedly high degree of rate variation. Our results reveal a >1,000-year-long development of genotype 6 in Asia, characterized by substantial phylogeographic structure and two distinct phases of epidemic history, before and during the 20th century. We conclude that HCV lineages representing preexisting and spatially restricted strains were involved in multiple, independent local epidemics during the 20th century. Our analysis explains the generation and maintenance of HCV diversity in Asia and could provide a template for further investigations of HCV spread in other regions. | 18,971,279 |
The novel micro-opioid receptor antagonist, [N-allyl-Dmt(1)]endomorphin-2, attenuates the enhancement of GABAergic neurotransmission by ethanol. | We investigated the effects of [N-allyl-Dmt(1)]endomorphin-2 (TL-319), a novel and highly potent micro-opioid receptor antagonist, on ethanol (EtOH)-induced enhancement of GABA(A) receptor-mediated synaptic activity in the hippocampus. Evoked and spontaneous inhibitory postsynaptic currents (eIPSCs and sIPSCs) were isolated from CA1 pyramidal cells from brain slices of male rats using whole-cell patch-clamp techniques. TL-319 had no effect on the baseline amplitude of eIPSCs or the frequency of sIPSCs. However, it induced a dose-dependent suppression of an ethanol-induced increase of sIPSC frequency with full reversal at concentrations of 500 nM and higher. The non-specific competitive opioid receptor antagonist naltrexone also suppressed EtOH-induced increases in sIPSC frequency but only at a concentration of 60 microM. These data indicate that blockade of micro-opioid receptors by low concentrations of [N-allyl-Dmt(1)]endomorphin-2 can reverse ethanol-induced increases in GABAergic neurotransmission and possibly alter its anxiolytic or sedative effects. This suggests the possibility that high potency opioid antagonists may emerge as possible candidate compounds for the treatment of ethanol addiction. | 18,971,291 |
Developmental sensitivity of hippocampal interneurons to ethanol: involvement of the hyperpolarization-activated current, Ih. | Ethanol (EtOH) has powerful effects on GABA(A) receptor-mediated neurotransmission, and we have previously shown that EtOH-induced enhancement of GABA(A) receptor-mediated synaptic transmission in the hippocampus is developmentally regulated. Because synaptic inhibition is determined in part by the firing properties of interneurons, we have investigated the mechanisms whereby EtOH influences the spontaneous firing characteristics and hyperpolarization-activated cation current (Ih) of hippocampal interneurons located in the near to the border of stratum lacunosum moleculare and s. radiatum of adolescent and adult rats. EtOH did not affect current injection-induced action potentials of interneurons that do not exhibit spontaneous firing. However, in neurons that fire spontaneously, EtOH enhanced the frequency of spontaneous action potentials (sAPs) in a concentration-dependent manner, an effect that was more pronounced in interneurons from adolescent rats, compared with adult rats. EtOH also modulated the afterhyperpolarization (AHP) that follows sAPs by shortening the tau(slow) decay time constant, and this effect was more pronounced in slices from adolescent rats. EtOH increased Ih amplitudes, accelerated Ih activation kinetics, and increased the maximal Ih conductance in interneurons from animals in both age groups. These effects were also more pronounced in interneurons from adolescents and persisted in the presence of glutamatergic and GABAergic blockers. However, EtOH failed to affect sAP firing in the presence of ZD7288 or cesium chloride. These results suggest that Ih may be of mechanistic significance in the effect of EtOH on interneuron spontaneous firing. | 18,971,298 |
Prokaryotic silencing (psi)RNAs in Pyrococcus furiosus. | In many prokaryotes, noncoding RNAs that arise from the clustered regularly interspaced short palindromic repeat (CRISPR) loci are now thought to mediate defense against viruses and other molecular invaders by an RNAi-like pathway. CRISPR loci contain multiple short regions of similarity to invader sequences separated by short repeat sequences, and are associated with resistance to infection by corresponding viruses. It is hypothesized that RNAs derived from these regions, termed prokaryotic silencing (psi)RNAs, guide Slicer-like complexes of partner proteins to destroy invader nucleic acids. Here we have investigated CRISPR-derived RNAs in the archaeon Pyrococcus furiosus. Northern analysis revealed multiple RNA species consistent with a proposed biogenesis pathway that includes full-length CRISPR locus transcripts and intermediates generated by endonucleolytic cleavages within the repeat sequences. However, our results identify the principal products of the CRISPR loci as small psiRNAs comprised primarily of invader-targeting sequence with perhaps only 5-10 nucleotides of CRISPR repeat sequence. These RNAs are the most abundant CRISPR RNA species in P. furiosus and are likely the guides for the effector complexes of the proposed prokaryotic RNAi (pRNAi) system. We analyzed cell-free extracts fractionated under non-denaturing conditions and found that the various CRISPR RNA species are components of distinct RNA-protein complexes, including at least two complexes that contain mature-length psiRNAs. Finally, RNAs are produced from all seven CRISPR loci present in the P. furiosus genome, and interestingly, the most recently acquired psiRNAs encoded proximal to the leader sequence of a CRISPR locus appear to be the most abundant. | 18,971,321 |
Mechanism of thermal decomposition of carbamoyl phosphate and its stabilization by aspartate and ornithine transcarbamoylases. | Carbamoyl phosphate (CP) has a half-life for thermal decomposition of <2 s at 100 degrees C, yet this critical metabolic intermediate is found even in organisms that grow at 95-100 degrees C. We show here that the binding of CP to the enzymes aspartate and ornithine transcarbamoylase reduces the rate of thermal decomposition of CP by a factor of >5,000. Both of these transcarbamoylases use an ordered-binding mechanism in which CP binds first, allowing the formation of an enzyme.CP complex. To understand how the enzyme.CP complex is able to stabilize CP we investigated the mechanism of the thermal decomposition of CP in aqueous solution in the absence and presence of enzyme. By quantum mechanics/molecular mechanics calculations we show that the critical step in the thermal decomposition of CP in aqueous solution, in the absence of enzyme, involves the breaking of the C O bond facilitated by intramolecular proton transfer from the amine to the phosphate. Furthermore, we demonstrate that the binding of CP to the active sites of these enzymes significantly inhibits this process by restricting the accessible conformations of the bound ligand to those disfavoring the reactive geometry. These results not only provide insight into the reaction pathways for the thermal decomposition of free CP in an aqueous solution but also show why these reaction pathways are not accessible when the metabolite is bound to the active sites of these transcarbamoylases. | 18,971,327 |
Structure of ratcheted ribosomes with tRNAs in hybrid states. | During protein synthesis, tRNAs and mRNA move through the ribosome between aminoacyl (A), peptidyl (P), and exit (E) sites of the ribosome in a process called translocation. Translocation is accompanied by the displacement of the tRNAs on the large ribosomal subunit toward the hybrid A/P and P/E states and by a rotational movement (ratchet) of the ribosomal subunits relative to one another. So far, the structure of the ratcheted state has been observed only when translation factors were bound to the ribosome. Using cryo-electron microscopy and classification, we show here that ribosomes can spontaneously adopt a ratcheted conformation with tRNAs in their hybrid states. The peptidyl-tRNA molecule in the A/P state, which is visualized here, is not distorted compared with the A/A state except for slight adjustments of its acceptor end, suggesting that the displacement of the A-site tRNA on the 50S subunit is passive and is induced by the 30S subunit rotation. Simultaneous subunit ratchet and formation of the tRNA hybrid states precede and may promote the subsequent rapid and coordinated tRNA translocation on the 30S subunit catalyzed by elongation factor G. | 18,971,332 |
Time to leave substantiation behind: findings from a national probability study. | Data from the National Survey of Child and Adolescent Well-being, a national probability study of children and families investigated for child maltreatment, were analyzed to answer the question: Do substantiated and unsubstantiated cases differ in rates of recidivism over 36 months? Recidivism was classified as (a) any re-reports, (b) substantiated re-reports and (c) subsequent foster care placements. Bivariate (survivor functions estimated by the Kaplan-Meier method) and multivariate (Cox regression modeling) analyses were conducted. The results revealed that risk of recidivism was similar regardless of substantiation status of the index investigation. We suggest that the substantiation label be removed from field use. Instead, we suggest that agencies record service needs in the families they serve, and also record whether or not the family meets criteria for referral to the family court. These would be far more practical and meaningful ways to measure child welfare services. | 18,971,346 |
Tissue-specific postprandial clearance is the major determinant of PPARgamma-induced triglyceride lowering in the rat. | Peroxisome proliferator-activated receptor-gamma (PPARgamma) agonism potently reduces circulating triglycerides (TG) in rodents and more modestly so in humans. This study aimed to quantify in vivo the relative contribution of hepatic VLDL-TG secretion and tissue-specific TG clearance to such action. Rats were fed an obesogenic diet, treated with the PPARgamma full agonist COOH (30 mg.kg(-1).day(-1)) for 3 wk, and studied in both the fasted and refed (fat-free) states. Hepatic VLDL-TG secretion rate was not affected by chronic COOH in the fasted state and was only modestly decreased (-30%) in refed rats. In contrast, postprandial VLDL-TG clearance was increased 2.6-fold by COOH, which concomitantly stimulated adipose tissue TG-derived lipid uptake and one of its major determinants, lipoprotein lipase (LPL) activity, in a highly depot-specific manner. TG-derived lipid uptake and LPL were indeed strongly increased in subcutaneous inguinal white adipose tissue and in brown adipose tissue, independently of the nutritional state, whereas of the three visceral fat depots examined (epididymal, retroperitoneal, mesenteric) only the latter responded consistently to COOH. Robust correlations (0.5 < r < 0.9) were observed between TG-derived lipid uptake and LPL in adipose tissues. The agonist did not increase LPL in muscle, and its enhancing action on postprandial muscle lipid uptake appeared to be mediated by post-LPL processes involving increased expression of fatty acid binding/transport proteins (aP2, likely in infiltrated adipocytes, FAT/CD36, and FATP-1). The study establishes in a diet-induced obesity model the major contribution of lipid uptake by specific, metabolically safe adipose depots to the postprandial hypotriglyceridemic action of PPARgamma agonism, and suggests a key role for LPL therein. | 18,971,352 |
Ciprofloxacin-resistant Salmonella enterica serovar typhi from Kuwait with novel mutations in gyrA and parC genes. | Blood isolates of Salmonella enterica serovar Typhi from two recently returned Bangladeshi patients in Kuwait were ciprofloxacin resistant, with ciprofloxacin MICs of 12 mg/liter for both isolates. Both isolates had three novel gyrA mutations (55-Leu-->Trp, 87-Asp-->Ala, and 106-Gln-->Arg) and three novel parC mutations (84-Glu-->Lys, 106-Trp-->Gly, and 128-Tyr-->Asp). | 18,971,360 |
Emergence and characterization of community-associated methicillin-resistant Staphyloccocus aureus infections in Denmark, 1999 to 2006. | The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) infections has changed worldwide. From being strictly nosocomial, MRSA is now frequently found as a community-associated (CA) pathogen. Denmark has been a low-prevalence country for MRSA since the mid-1970s but has in recent years experienced an increasing number of CA-MRSA cases. The aim of this study was to describe the emergence of CA-MRSA infections in Denmark. All Danish MRSA specimens and corresponding clinical data from 1999 to 2006 were investigated. Isolates were analyzed by antibiotic resistance and molecular typing and were assigned to clonal complexes (CC). Clinical data were extracted from discharge summaries and general practitioners' notes, from which assessments of community association were made for all infected cases. CA-MRSA cases constituted 29.4% of all MRSA infections (n = 1,790) and an increasing proportion of the annual numbers of MRSA infections during the study period. CA-MRSA was associated with a young age, skin and soft tissue infections, and non-Danish origin. Transmission between household members was frequently reported. Molecular typing showed >60 circulating clones, where 89.4% of the isolates belonged to five CC (CC80, CC8, CC30, CC5, and CC22), 81.2% carried staphylococcal cassette chromosome mec IV, and 163/244 (69.4%) were positive for Panton-Valentine leukocidin. Clinical and microbiological characteristics indicated that import of MRSA occurs frequently. Resistance to > or =3 antibiotic classes was observed for 48.8% of the isolates. The emergence of CA-MRSA in Denmark was caused by diverse strains, both well-known and new CA-MRSA strains. The results suggest multiple introductions of MRSA as an important source for CA-MRSA infections in Denmark. | 18,971,362 |
Chronic treatment with the dipeptidyl peptidase-4 inhibitor BI 1356 [(R)-8-(3-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione] increases basal glucagon-like peptide-1 and improves glycemic control in diabetic rodent models. | Antidiabetic effects of dipeptidyl peptidase-4 (DPP-4) inhibitors are exerted by potentiation of the biological activity of incretin hormones like glucagon-like peptide (GLP)-1. BI 1356 [proposed trade name Ondero; (R)-8-(3-amino-piperidin-1-yl)-7-but-2-ynyl-3-methyl-1-(4-methyl-quinazolin-2-ylmethyl)-3,7-dihydro-purine-2,6-dione] is a novel competitive, selective, potent, and long-acting DPP-4 inhibitor under clinical development for the treatment of type 2 diabetes. The effect of 1 to 2 months of chronic dosing of BI 1356 in two different animal models was investigated. The first is a primarily genetic model (Zucker diabetic fatty rats), and the second is a nongenetic model (mice with diabetes induced by a combination of high-fat diet and low-dose streptozotocin). BI 1356 was shown to lower HbA1c after multiple dosing in both models. The improvement of glycemic control achieved in disease models of different etiology suggests that BI 1356 would also be efficacious in treating a broad spectrum of type 2 diabetic patients. In addition, multiple dosing of BI 1356 leads to a sustained increase in basal levels of active GLP-1 in the systemic circulation, with expected long-term benefits on pancreatic alpha- and beta-cells. The effects on HbA1c and GLP-1 were superior to the short-acting DPP-4 inhibitor vildagliptin, demonstrating the potential of BI 1356 as a once daily treatment for type 2 diabetes at low therapeutic doses. | 18,971,371 |
Improving gait in multiple sclerosis using robot-assisted, body weight supported treadmill training. | The majority of patients with multiple sclerosis (MS) develop progressive gait impairment, which can start early in the disease and worsen over a lifetime. A promising outpatient intervention to help improve gait function with potential for addressing this treatment gap is task-repetitive gait training. Body weight supported treadmill training (BWSTT) with or without robotic assistance (Lokomat) was tested using a randomized crossover design in 13 patients with relapsing-remitting, secondary progressive or primary progressive MS. Patients received 6 training sessions over 3 weeks of each intervention. Outcomes included changes in the timed 25-foot walk (T25FW), the 6-minute walk treadmill test (6MW) distance, the Kurtzke Expanded Disability Status Scale (EDSS), as well as double-limb support time and step length ratio. There were no major differences in outcomes between treatment groups. The study population significantly improved on gait outcomes and the EDSS following BWSTT, including a 31% improvement in the T25FW, a 38.5% improvement in the 6MW, and a 1-point gain for the EDSS. Differences in pre/post changes were noted depending on gender, disease subtype, affected limb, and baseline EDSS. Although no differences in gait outcomes or the EDSS were found between treatment groups, this small pilot study of task-repetitive gait training resulted in significant within-subject improvements. BWSTT appears to be an activity-dependent intervention with potential to reduce gait impairment in MS. | 18,971,381 |
The US health care system: Part 1: Our current system. | The US health care crisis is of great concern to American neurologists. The United States has the world's most expensive health care system yet one-sixth of Americans are uninsured. The cost and volume of procedures is expanding, while reimbursement for office visits is declining. Pharmaceutical costs, durable goods, and home health care are growing disproportionately to other services. Carriers spend more for their own administration and profit than on payments to physicians. This first article on the US health care system identifies problems and proposes solutions, many of which are championed by the American Academy of Neurology through its legislative and regulatory committees. | 18,971,443 |
Expression and regulation of IFNalpha/beta receptor in IFNbeta-treated patients with multiple sclerosis. | The cytokine interferon beta (IFNbeta) is successfully used in the treatment of multiple sclerosis (MS), although there is a high degree of variability in the response. A common mechanism involved in the modulation of responsiveness to cytokines is represented by regulation of their receptor expression through autocrine ligand-mediated loops. The present study is aimed at investigating the regulation of IFNalpha/beta receptor (IFNAR) during IFNbeta therapy in patients with MS and at correlating it with the biologic responsiveness to the cytokine. Quantitative PCR measurements of IFNAR-1 and the three IFNAR-2 isoforms were performed in 141 patients after short-term and long-term treatment. Patients were also regularly screened for anti-IFNbeta neutralizing antibodies (NAbs). IFN-inducible myxovirus resistance protein A messenger RNA was used as an indicator of bioactivity. Pretreatment levels of IFNAR-2 in patients were lower overall than in controls (p = 0.038), and high levels correlated with greater bioactivity. Upon prolonged treatment, NAb-negative patients displayed a state of decreased transmembrane IFNAR-2 expression (p < or = 0.025), whereas levels of soluble IFNAR-2 were slightly increased (p < 0.0001). The presence of NAbs reversed these effects (p < or = 0.0056). In NAb-positive patients, pretreatment expression levels of both transmembrane IFNAR-2 isoforms were significantly lower than in NAb-negative patients (p < or = 0.0089). Findings show that interferon-alpha/beta receptor (IFNAR)-2 isoforms are important regulators of the responsiveness to endogenous and systemically administered interferon beta (IFNbeta). They show a dual action, agonistic and antagonistic, that influences both the magnitude and the nature of the biologic response to IFNbeta. Levels of IFNAR-2 are regulated with the aim of keeping the body in a state of equilibrium, even when nonphysiologic stimuli are present. | 18,971,450 |
Double dissociation of the effects of medial and orbital prefrontal cortical lesions on attentional and affective shifts in mice. | Many neuropsychiatric diseases are associated with cognitive rigidity linked to prefrontal dysfunction. For example, schizophrenia and Parkinson's disease are associated with performance deficits on the Wisconsin Card Sorting Test, which evaluates attentional set shifting. Although the genetic underpinnings of these disorders can be reproduced in mice, there are few models for testing the functional consequences. Here, we demonstrate that an analog of the Wisconsin Card Sorting Test, developed in marmosets and recently adapted to rats, is a behavioral model of prefrontal function in mice. Systematic analysis demonstrated that formation of the attentional set in mice is dependent on the number of problem sets. We found that mice, like rats and primates, exhibit both affective and attentional sets, and these functions are disrupted by neurotoxic damage to orbitofrontal and medial prefrontal cortical areas, respectively. These data are identical to studies in rats and similar to the deficits reported after prefrontal damage in a comparable task in marmosets. These results provide a behavioral model to assess prefrontal function in mice. | 18,971,455 |
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